Collection of ultrafine diesel particulate matter (DPM) in cylindrical single-stage wet electrostatic precipitators.

PubMed

Saiyasitpanich, Phirun; Keener, Tim C; Lu, Mingming; Khang, Soon-Jai; Evans, Douglas E

2006-12-15

Long-term exposures to diesel particulate matter (DPM) emissions are linked to increasing adverse human health effects due to the potential association of DPM with carcinogenicity. Current diesel vehicular particulate emission regulations are based solely upon total mass concentration, albeit it is the submicrometer particles that are highly respirable and the most detrimental to human health. In this study, experiments were performed with a tubular single-stage wet electrostatic precipitator (wESP) to evaluate its performance for the removal of number-based DPM emissions. A nonroad diesel generator utilizing a low sulfur diesel fuel (500 ppmw) operating under varying load conditions was used as a stationary DPM emission source. An electrical low-pressure impactor (ELPI) was used to quantify the number concentration distributions of diesel particles in the diluted exhaust gas at each tested condition. The wESP was evaluated with respect to different operational control parameters such as applied voltage, gas residence time, etc., to determine their effect on overall collection efficiency, as well as particle size dependent collection efficiency. The results show that the total DPM number concentrations in the untreated diesel exhaust are in the magnitude of approximately108/cm(3) at all engine loads with the particle diameter modes between 20 and 40 nm. The measured collection efficiency of the wESP operating at 70 kV based on total particle numbers was 86% at 0 kW engine load and the efficiency decreased to 67% at 75 kW due to a decrease in gas residence time and an increase in particle concentrations. At a constant wESP voltage of 70 kV and at 75 kW engine load, the variation of gas residence time within the wESP from approximately 0.1 to approximately 0.4 s led to a substantial increase in the collection efficiency from 67% to 96%. In addition, collection efficiency was found to be directly related to the applied voltage, with increasing collection efficiency measured for increases in applied voltage. The collection efficiency based on particle size had a minimum for sizes between 20 and 50 nm, but at optimal wESP operating conditions it was possible to remove over 90% of all particle sizes. A comparison of measured and calculated collection efficiencies reveals that the measured values are significantly higher than the predicted values based on the well-known Deutsch equation.

Transport of particle-associated elements in two agriculture-dominated boreal river systems.

PubMed

Marttila, Hannu; Saarinen, Tuomas; Celebi, Ahmet; Kløve, Bjørn

2013-09-01

Transport of particulate pollutants in fluvial systems can contribute greatly to total loads. Understanding transport mechanics under different hydrological conditions is key in successful load estimation. This study analysed trace elements and physico-chemical parameters in time-integrated suspended sediment samples, together with dissolved and total concentrations of pollutants, along two agriculture- and peatland-dominated boreal river systems. The samples were taken in a spatially and temporally comprehensive sampling programme during the ice-free seasons of 2010 and 2011. The hydrochemistry and transport of particle-bound elements in the rivers were strongly linked to intense land use and acid sulphate soils in the catchment area, with arable, pasture and peat areas in particular being main diffuse sources. There were significant seasonal and temporal variations in dissolved and particulate fluxes, but spatial variations were small. Continuous measurements of EC, turbidity and discharge proved to be an accurate indicator of dissolved and particulate fluxes. Overall, the results show that transport of particle-bound elements makes a major contribution to total transport fluxes in agriculture-dominated boreal rivers. Copyright © 2013 Elsevier B.V. All rights reserved.

Emission reduction from diesel engine using fumigation methanol and diesel oxidation catalyst.

PubMed

Zhang, Z H; Cheung, C S; Chan, T L; Yao, C D

2009-07-15

This study is aimed to investigate the combined application of fumigation methanol and a diesel oxidation catalyst for reducing emissions of an in-use diesel engine. Experiments were performed on a 4-cylinder naturally-aspirated direct-injection diesel engine operating at a constant speed of 1800 rev/min for five engine loads. The experimental results show that at low engine loads, the brake thermal efficiency decreases with increase in fumigation methanol; but at high loads, it slightly increases with increase in fumigation methanol. The fumigation method results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO(2)) emissions, but decrease in nitrogen oxides (NO(x)), smoke opacity and the particulate mass concentration. For the submicron particles, the total number of particles decreases. In all cases, there is little change in geometrical mean diameter of the particles. After catalytic conversion, the HC, CO, NO(2), particulate mass and particulate number concentrations were significantly reduced at medium to high engine loads; while the geometrical mean diameter of the particles becomes larger. Thus, the combined use of fumigation methanol and diesel oxidation catalyst leads to a reduction of HC, CO, NO(x), particulate mass and particulate number concentrations at medium to high engine loads.

A multi-particle crushing apparatus for studying rock fragmentation due to repeated impacts

NASA Astrophysics Data System (ADS)

Huang, S.; Mohanty, B.; Xia, K.

2017-12-01

Rock crushing is a common process in mining and related operations. Although a number of particle crushing tests have been proposed in the literature, most of them are concerned with single-particle crushing, i.e., a single rock sample is crushed in each test. Considering the realistic scenario in crushers where many fragments are involved, a laboratory crushing apparatus is developed in this study. This device consists of a Hopkinson pressure bar system and a piston-holder system. The Hopkinson pressure bar system is used to apply calibrated dynamic loads to the piston-holder system, and the piston-holder system is used to hold rock samples and to recover fragments for subsequent particle size analysis. The rock samples are subjected to three to seven impacts under three impact velocities (2.2, 3.8, and 5.0 m/s), with the feed size of the rock particle samples limited between 9.5 and 12.7 mm. Several key parameters are determined from this test, including particle size distribution parameters, impact velocity, loading pressure, and total work. The results show that the total work correlates well with resulting fragmentation size distribution, and the apparatus provides a useful tool for studying the mechanism of crushing, which further provides guidelines for the design of commercial crushers.

Estimation of the emission factors of PAHs by traffic with the model of atmospheric dispersion and deposition from heavy traffic road.

PubMed

Ozaki, N; Tokumitsu, H; Kojima, K; Kindaichi, T

2007-01-01

In order to consider the total atmospheric loadings of the PAHs (polycyclic aromatic hydrocarbons) from traffic activities, the emission factors of PAHs were estimated and from the obtained emission factors and vehicle transportation statistics, total atmospheric loadings were integrated and the loadings into the water body were estimated on a regional scale. The atmospheric concentration of PAHs was measured at the roadside of a road with heavy traffic in the Hiroshima area in Japan. The samplings were conducted in summer and winter. Atmospheric particulate matters (fine particle, 0.6-7 microm; coarse particle, over 7 microm) and their PAH concentration were measured. Also, four major emission sources (gasoline and diesel vehicle emissions, tire and asphalt debris) were assumed for vehicle transportation activities, the chemical mass balance method was applied and the source partitioning at the roadside was estimated. Furthermore, the dispersion of atmospheric particles from the vehicles was modelled and the emission factors of the sources were determined by the comparison to the chemical mass balance results. Based on emission factors derived from the modelling, an atmospheric dispersion model of nationwide scale (National Institute of Advanced Industrial Science and Technology - Atmospheric Dispersion Model for Exposure and Risk assessment) was applied, and the atmospheric concentration and loading to the ground were calculated for the Hiroshima Bay watershed area.

Research on the impact of surface properties of particle on damping effect in gear transmission under high speed and heavy load

NASA Astrophysics Data System (ADS)

Xiao, Wangqiang; Chen, Zhiwei; Pan, Tianlong; Li, Jiani

2018-01-01

The vibration and noise from gear transmission have great damage on the mechanical equipment and operators. Through inelastic collisions and friction between particles, the energy can be dissipated in gear transmission. A dynamic model of particle dampers in gear transmission was put forward in this paper. The performance of particle dampers in centrifugal fields under different rotational speeds and load was investigated. The surface properties such as the impact of coefficient of restitution and friction coefficient of the particle on the damping effect were analyzed and the total energy loss was obtained by discrete element method (DEM). The vibration from time-varying mesh stiffness was effectively reduced by particle dampers and the optimum coefficient of restitution was discovered under different rotational speeds and load. Then, a test bench for gear transmission was constructed, and the vibration of driven gear and driving gear were measured through a three-directional wireless acceleration sensor. The research results agree well with the simulation results. While at relatively high speed, smaller coefficient of restitution achieves better damping effect. As to friction coefficient, at relatively high speed, the energy dissipation climbs up and then declines with the increase of the friction coefficient. The results can provide guidelines for the application of particle damper in gear transmission.

Predicting fractional bed load transport rates: Application of the Wilcock‐Crowe equations to a regulated gravel bed river

USGS Publications Warehouse

Gaeuman, David; Andrews, E.D.; Krause, Andreas; Smith, Wes

2009-01-01

Bed load samples from four locations in the Trinity River of northern California are analyzed to evaluate the performance of the Wilcock‐Crowe bed load transport equations for predicting fractional bed load transport rates. Bed surface particles become smaller and the fraction of sand on the bed increases with distance downstream from Lewiston Dam. The dimensionless reference shear stress for the mean bed particle size (τ*rm) is largest near the dam, but varies relatively little between the more downstream locations. The relation between τ*rm and the reference shear stresses for other size fractions is constant across all locations. Total bed load transport rates predicted with the Wilcock‐Crowe equations are within a factor of 2 of sampled transport rates for 68% of all samples. The Wilcock‐Crowe equations nonetheless consistently under‐predict the transport of particles larger than 128 mm, frequently by more than an order of magnitude. Accurate prediction of the transport rates of the largest particles is important for models in which the evolution of the surface grain size distribution determines subsequent bed load transport rates. Values of τ*rm estimated from bed load samples are up to 50% larger than those predicted with the Wilcock‐Crowe equations, and sampled bed load transport approximates equal mobility across a wider range of grain sizes than is implied by the equations. Modifications to the Wilcock‐Crowe equation for determining τ*rm and the hiding function used to scale τ*rm to other grain size fractions are proposed to achieve the best fit to observed bed load transport in the Trinity River.

A Study of the Effects of Relative Humidity on Small Particle Adhesion to Surfaces

NASA Technical Reports Server (NTRS)

Whitfield, W. J.; David, T.

1971-01-01

Ambient dust ranging in size from less than one micron up to 140 microns was used as test particles. Relative humidities of 33% to 100% were used to condition test surfaces after loading with the test particles. A 20 psi nitrogen blowoff was used as the removal mechanism to test for particle adhesion. Particles were counted before and after blowoff to determine retention characteristics. Particle adhesion increased drastically as relative humidity increased above 50%. The greatest adhesion changes occurred within the first hour of conditioning time. Data are presented for total particle adhesion, for particles 10 microns and larger, and 50 microns and larger.

Characteristics of particulate emissions from a diesel generator fueled with varying blends of biodiesel and fossil diesel.

PubMed

Tsai, Jen-Hsiung; Chen, Shui-Jen; Huang, Kuo-Lin; Lee, Wen-Jhy; Kuo, Wen-Chien; Lin, Wen-Yinn

2011-01-01

This study investigated the particulate matter (PM), particle-bound carbons, and polycyclic aromatic hydrocarbons (PAHs) emitted from a diesel-engine generator fuelled with blends of pure fossil diesel oil (D100) and varying percentages of waste-edible-oil biodiesel (W10, 10 vol %; W20, 20 vol %; W30, 30 vol %; and W50, 50 vol %) under generator loads of 0, 1.5, and 3 kW. On average, the PM emission factors of all blends was 30.5 % (range, 13.7-52.3 %) lower than that of D100 under the tested loads. Substituting pure fossil diesel oil with varying percentages of waste-edible-oil biodiesel reduced emissions of particle-bound total carbon (TC) and elemental carbon (EC). The W20 blend had the lowest particle-bound organic carbon (OC) emissions. Notably, W10, W20, and W30 also had lower Total-PAH emissions and lower total equivalent toxicity (Total-BaP(eq)) compared to D100. Additionally, the brake-specific fuel consumption of the generator correlated positively with the ratio of waste-edible-oil biodiesel to pure fossil diesel. However, generator energy efficiency correlated negatively with the ratio of waste-edible-oil biodiesel to pure fossil diesel.

[Experimental study on the characteristics polycyclic aromatic hydrocarbon emissions of diesel engine burnt by different fuels].

PubMed

Wang, Zhong; An, Yu-Guang; Xu, Guang-Ju; Wang, Xiao-Zhe

2011-07-01

The polycyclic aromatic hydrocarbons (PAHs) were measured by glass fiber filter and XAD-2 collector, ultrasonic extraction, soxhlet extraction and GC-MS analysis equipment. The exhaust emission of the DI single cylinder diesel engine fueled with pure diesel, biodiesel and biodiesel blends of 50% (B50) were measured. The results indicate that the particle-phase PAHs emissions of diesel engine decrease with the increasing of load. The gas-phase PAHs emissions of diesel engine decrease with the increasing of load in the beginning and it turns to going up with further increasing of load. The particle-phase and gas-phase PAHs emissions of biodiesel decrease and mean concentration are lower than that of diesel. The total PAHs emission concentration of biodisesl is 41.1-70.1 microg/m3. Total PAHs mean concentration emissions of biodiesel is decreased 33.3% than that of diesel. The mass proportion of three-ring PAHs emissions of those 3 kinds tested fuels is about 44% in the total PAHs. Biodiesel can increase the proportion of three-ring PAHs. Toxic equivalence of PAHs emissions of biodiesel are greatly lower than that of diesel. It is less harmful to human than diesel fuel.

Electromagnetic absorption behaviour of ferrite loaded three phase carbon fabric composites

NASA Astrophysics Data System (ADS)

Jagatheesan, Krishnasamy; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

2018-02-01

This article investigates the electromagnetic absorption behaviours of carbon helical yarn fabric reinforced composites and manganese-zinc (Mn-Zn) ferrite particles loaded 3 phase fabric composites. A carbon helical yarn having stainless steel core was prepared and made into single jersey knitted fabric. The composite was prepared by sandwiching a fabric with polypropylene films and thermal pressed. The absorption values of helical yarn fabric composite was observed to be less in the C band region (4-8 GHz). For improving the absorption coefficients of composite, Mn-Zn ferrite particles were dispersed in the polypropylene (PP) composite. The ferrite loaded PP composites exhibited better permittivity and permeability values, hence the absorption loss of the composite was improved. The helical yarn fabric reinforced with Mn-Zn ferrite/PP composite showed larger absorption coefficients than virgin PP/fabric composite. The change in thermal stability and particle size distribution in the Mn-Zn ferrite/PP composite was also analyzed. At higher ferrite concentration, bimodal particle distribution was observed which increased the conductivity and shielding effectiveness (SE) of the composite. In addition, complex permittivity value was also increased for higher incident frequency (4-8 GHz). As the ferrite content increases, the dielectric loss and magnetic permeability of PP/ferrite increases due to increased magnetic loss. Hence, ferrite loaded PP composite showed the total SE of -14.2 dB with the absorption coefficients of 0.717. The S1C7 fabric composite having ferrite dispersion showed the better absorption loss and lower reflection coefficient of 14.2 dB and 0.345 respectively compared to virgin PP/helical yarn fabric composite. The increasing ferrite content (45 wt%) improved the absorption loss and total SE. Though, ferrite based fabric composite exhibits moderate absorptive shielding, it can be used as shielding panels in the electronic industries.

Effects of Porous Polystyrene Resin Parameters on Candida antarctica Lipase B Adsorption, Distribution, and Polyester Synthesis Activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen,B.; Miller, M.; Gross, R.

2007-01-01

Polystyrene resins with varied particle sizes (35 to 350-600 {mu}m) and pore diameters (300-1000 {angstrom}) were employed to study the effects of immobilization resin particle size and pore diameter on Candida antarctica Lipase B (CALB) loading, distribution within resins, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed rapidly (saturation time {<=}4 min) for particle sizes 120 {mu}m (pore size = 300 {angstrom}). Infrared microspectroscopy showed that CALB forms protein loading fronts regardless of resin particle size at similar enzyme loadings ({approx}8%). From the IR images, the fractions of total surface area available to the enzyme aremore » 21, 33, 35, 37, and 88% for particle sizes 350-600, 120, 75, 35 {mu}m (pore size 300 {angstrom}), and 35 {mu}m (pore size 1000 {angstrom}), respectively. Titration with methyl p-nitrophenyl n-hexylphosphate (MNPHP) showed that the fraction of active CALB molecules adsorbed onto resins was {approx}60%. The fraction of active CALB molecules was invariable as a function of resin particle and pore size. At {approx}8% (w/w) CALB loading, by increasing the immobilization support pore diameter from 300 to 1000 {angstrom}, the turnover frequency (TOF) of {var_epsilon}-caprolactone ({var_epsilon}-CL) to polyester increased from 12.4 to 28.2 s{sup -1}. However, the {var_epsilon}-CL conversion rate was not influenced by changes in resin particle size. Similar trends were observed for condensation polymerizations between 1,8-octanediol and adipic acid. The results herein are compared to those obtained with a similar series of methyl methacrylate resins, where variations in particle size largely affected CALB distribution within resins and catalyst activity for polyester synthesis.« less

[Alterations in expression of F-actin and DNA of fluid shear stress treated-mesenchymal stem cells affected by titanium particles loading].

PubMed

Wu, Jiang; Chen, Huiqing; Cao, Hui; Zhou, Jiang; Zhang, Li; Sung, K L

2004-02-01

Particulate wear debris within the bone-prosthesis microenvironment generated by normal wear and corrosion of orthopaedic implants is considered to be one of the main factors responsible for chronic aseptic inflammation and development of osteolysis in the long-term instability and failure of total joint arthroplasty. While the decrease in bone volume caused by wear debris-induced osteolysis could have been compensated by enough new bone matrix secreted by osteoblasts. Actually, the normal osteoblastic population depend on the regular differentiation and proliferation of their progenitor cells--bone marrow mesenchymal stem cells (MSCs). This study aims to investigate the potential mechanism for the rat MSCs cytotoxicity upon exposure to Titanium (Ti) particles. Rat mesenchymal stem cells (rMSCs) isolated from 3-month-old male Sprague-Dawley rats by Percoll intensity gradient method were cultured in DMEM medium (low glucose) supplemented with 10% fetal bovine serum, 100 U/ml penicillin, and 100 micrograms/ml streptomycin in a humidified incubator with 5% CO2 at 37 degrees C. In order to gain the homogenous cell population, rMSCs were passaged to 3-4th subpassage which were used in all the experiment groups. Then rMSCs were seeded in the 6 well culture plates and exposed to three different circle diameters (mean size, TD1: 0.9 micron, TD2: 2.7 microns, TD3: 6.9 microns) with three different concentrations (0.1 wt%, 0.05 wt%, 0.01 wt%, W/V) at different durations (8 h, 16 h, 24 h,), respectively. Unexposed rMSCs were used as control. In the given periods of Ti loading, fluid shear stress (FSS) was applied to each group cells. The expression of F-actin and DNA of the rMSCs at the indicated time were determined with laser confocal scanning microscopy and image analysis software. The results showed that there was up-regulation expression of F-actin in the rMSCs without Ti particles loading but in the presence of FSS. Ti particles loading can suppress the expression of F-action and DNA of rMSCs, but this down-regulation response varied with the three circle diameter, concentrations and durations of Ti particles. Among three kinds of diametrically different Ti particles, submicron Ti particles (0.9 micron) had the greatest suppressive response on rMSCs, together with some apoptosis bodies. Under the same diameter condition, the inhibition induced by Ti particles loading was in a manner dependent on the particles concentration and exposure duration. The reductive effects produced from 0.1 wt% Ti was the greatest and earliest among the responses from Ti particles at three different concentrations; and the lower the concentration, the weaker the repressive influence. Furthermore, with the elongation of exposure to Ti particles, the expression of F-actin and DNA decreased gradually, the lowest level was at 32 h. These findings demonstrated that Ti particles loading can attenuate rMSCs' viability in a manner dependent on the circle diameter, particles concentration, treatment period, suggesting that a reduction in the number of viable MSCs together with a compromise of the their differentiation into functional osteoblast may exacerbate aseptic loosening of total joint implant. Further investigation into particles-mediated suppression of MCSs viability may reveal novel mechanism of implant loosening and aid in development and application of osteolytic drug therapy and the optimization of design and selection of future orthopaedic biomaterials, thereby improving long-term compatibility and stability for arthroplasty patients.

Effect of particle aging on chemical characteristics, smoldering, and fire behavior in mixed-conifer masticated fuel

Treesearch

Pamela G. Sikkink; Theresa B. Jain; James Reardon; Faith Ann Heinsch; Robert E. Keane; Bret Butler; L. Scott Baggett

2017-01-01

Mastication is a silvicultural technique that grinds, shreds, or chops trees or shrubs into pieces and redistributes the biomass onto the forest floor to form a layer of woody debris. Unlike other fuel treatments that remove this biomass, masticated biomass often remains on site, which increases total fuel loading and causes concern over how the masticated particles...

Evaluation of the Multi-Chambered Treatment Train, a retrofit water-quality management device

USGS Publications Warehouse

Corsi, Steven R.; Greb, Steven R.; Bannerman, Roger T.; Pitt, Robert E.

1999-01-01

This paper presents the results of an evaluation of the benefits and efficiencies of a device called the Multi-Chambered Treatment Train (MCTT), which was installed below the pavement surface at a municipal maintenance garage and parking facility in Milwaukee, Wisconsin. Flow-weighted water samples were collected at the inlet and outlet of the device during 15 storms, and the efficiency of the device was based on reductions in the loads of 68 chemical constituents and organic compounds. High reduction efficiencies were achieved for all particulate-associated constituents, including total suspended solids (98 percent), total phosphorus (88 percent), and total recoverable zinc (91 percent). Reduction rates for dissolved fractions of the constituents were substantial, but somewhat lower (dissolved solids, 13 percent; dissolved phosphorus, 78 percent; dissolved zinc, 68 percent). The total dissolved solids load, which originated from road salt storage, was more than four times the total suspended solids load. No appreciable difference was detected between particle-size distributions in inflow and outflow samples.

Carbon loading of alveolar macrophages in adults and children exposed to biomass smoke particles.

PubMed

Kulkarni, Neeta S; Prudon, Benjamin; Panditi, Sri L; Abebe, Yekoye; Grigg, Jonathan

2005-06-01

Exposure to carbonaceous particles from biomass burning is associated with increased respiratory morbidity in both women and children in the developing world. However, the amount of carbon reaching lower airway cells has not been determined in these populations. Alveolar macrophages (AM) remove inhaled particulate matter (PM), and are implicated in the pathogenesis of PM-induced lung disease. In this study, we aimed to compare AM carbon loading in women and children exposed to biomass PM in Gondar, Ethiopia, with individuals exposed to fossil-fuel PM in the developed world (Leicester, UK). To achieve these aims, we sampled AM from Ethiopian mothers and children, and from UK adults and children using induced sputum (IS). AM were imaged under light microscopy, and the total two-dimensional surface area of carbon within each AM determined by image analysis. AM containing carbon were detected in all subjects. The total surface area of carbon per AM was higher in Ethiopian women (n=10) compared with UK adults (n=10, median 9.19 vs. 0.71 microm2/AM, p=0.0002). Similarly, the total surface area of carbon per AM was higher in Ethiopian children (n=10) compared with UK children (n=10, 3.32 vs. 0.44 microm2/AM, p=0.0002). However, loading in Ethiopian children was lower than paired maternal levels (3.32 vs. 9.19 microm2/AM, p=0.011). We conclude that analysis of AM obtained by induced sputum is a practical way of quantifying natural exposure of the lower airway to carbonaceous particles from the burning of biomass fuels.

Using large volume samplers for the monitoring of particle bound micro pollutants in rivers

NASA Astrophysics Data System (ADS)

Kittlaus, Steffen; Fuchs, Stephan

2015-04-01

The requirements of the WFD as well as substance emission modelling at the river basin scale require stable monitoring data for micro pollutants. The monitoring concepts applied by the local authorities as well as by many scientists use single sampling techniques. Samples from water bodies are usually taken in volumes of about one litre and depending on predetermined time steps or through discharge thresholds. For predominantly particle bound micro pollutants the small sample size of about one litre results in a very small amount of suspended particles. To measure micro pollutant concentrations in these samples is demanding and results in a high uncertainty of the measured concentrations, if the concentration is above the detection limit in the first place. In many monitoring programs most of the measured values were below the detection limit. This results in a high uncertainty if river loads were calculated from these data sets. The authors propose a different approach to gain stable concentration values for particle bound micro pollutants from river monitoring: A mixed sample of about 1000 L was pumped in a tank with a dirty-water pump. The sampling usually is done discharge dependant by using a gauge signal as input for the control unit. After the discharge event is over or the tank is fully filled, the suspended solids settle in the tank for 2 days. After this time a clear separation of water and solids can be shown. A sample (1 L) from the water phase and the total mass of the settled solids (about 10 L) are taken to the laboratory for analysis. While the micro pollutants can't hardly be detected in the water phase, the signal from the sediment is high above the detection limit, thus certain and very stable. From the pollutant concentration in the solid phase and the total tank volume the initial pollutant concentration in the sample can be calculated. If the concentration in the water phase is detectable, it can be used to correct the total load. This relatively low cost approach (less costs for analysis because of small sample number) allows to quantify the pollutant load, to derive dissolved-solid partition coefficients and to quantify the pollutant load in different particle size classes.

Synthesis of wrinkled mesoporous silica and its reinforcing effect for dental resin composites.

PubMed

Wang, Ruili; Habib, Eric; Zhu, X X

2017-10-01

The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N 2 adsorption-desorption measurements. The mechanical properties of resin composites containing silanized WMS and nonporous smaller silica were evaluated with a universal mechanical testing machine. Field-emission scanning electron microscopy was used to study the fracture morphology of dental composites. Resin composites including silanized silica particles (average diameter of 507nm) served as the control group. Higher filler loading of silanized WMS substantially improved the mechanical properties of the neat resin matrix, over the composites loaded with regular silanized silica particles similar in size. The impregnation of smaller secondary silica particles with diameters of 90 and 190nm, denoted respectively as Si90 and Si190, increased the filler loading of the bimodal WMS filler (WMS-Si90 or WMS-Si190) to 60wt%, and the corresponding composites exhibited better mechanical properties than the control fillers made with regular silica particles. Among all composites, the optimal WMS-Si190- filled composite (mass ratio WMS:Si190=10:90, total filler loading 60wt%) exhibited the best mechanical performance including flexural strength, flexural modulus, compressive strength and Vickers microhardness. The incorporation of WMS and its mixed bimodal fillers with smaller silica particles led to the design and formulation of dental resin composites with superior mechanical properties. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Analysis of particulate contamination on tape lift samples from the VETA optical surfaces

NASA Technical Reports Server (NTRS)

Germani, Mark S.

1992-01-01

Particulate contamination analysis was carried out on samples taken from the Verification Engineering Test Article (VETA) x-ray detection system. A total of eighteen tape lift samples were taken from the VETA optical surfaces. Initially, the samples were tested using a scanning electron microscope. Additionally, particle composition was determined by energy dispersive x-ray spectrometry. Results are presented in terms of particle loading per sample.

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Under contract with the US Department of Energy (DE-AC22-92PCO0367), Pittsburgh Energy Technology Center, Radian Corporation has conducted a test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPS). Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical charactization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on themore » relative toxicological effects of exposure to particulate emissions.« less

Experimental investigation of the effect of inlet particle properties on the capture efficiency in an exhaust particulate filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viswanathan, Sandeep; Rothamer, David; Zelenyuk, Alla

The impact of inlet particle properties on the filtration performance of clean and particulate matter (PM) laden cordierite filter samples was evaluated using PM generated by a spark-ignition direct-injection (SIDI) engine fuelled with tier II EEE certification gasoline. Prior to the filtration experiments, a scanning mobility particle spectrometer (SMPS) was used to measure the electrical-mobility based particle size distribution (PSD) in the SIDI exhaust from distinct engine operating conditions. An advanced aerosol characterization system that comprised of a centrifugal particle mass analyser (CPMA), a differential mobility analyser (DMA), and a single particle mass spectrometer (SPLAT II) was used to obtainmore » additional information on the SIDI particulate, including particle composition, mass, and dynamic shape factors (DSFs) in the transition () and free-molecular () flow regimes. During the filtration experiments, real-time measurements of PSDs upstream and downstream of the filter sample were used to estimate the filtration performance and the total trapped mass within the filter using an integrated particle size distribution method. The filter loading process was paused multiple times to evaluate the filtration performance in the partially loaded state. The change in vacuum aerodynamic diameter () distribution of mass-selected particles was examined for flow through the filter to identify whether preferential capture of particles of certain shapes occurred in the filter. The filter was also probed using different inlet PSDs to understand their impact on particle capture within the filter sample. Results from the filtration experiment suggest that pausing the filter loading process and subsequently performing the filter probing experiments did not impact the overall evolution of filtration performance. Within the present distribution of particle sizes, filter efficiency was independent of particle shape potentially due to the diffusion-dominant filtration process. Particle mobility diameter and trapped mass within the filter appeared to be the dominant parameters that impacted filter performance.« less

Distribution and transport of polychlorinated biphenyls and associated particulates in the Hayton Millpond, south branch Manitowoc River, 1993-95

USGS Publications Warehouse

Steuer, Jeffrey S.; Hall, David W.; Fitzgerald, Sharon A.

1999-01-01

The distribution and transport of polychlorinated biphenyl (PCB) congeners was determined at two sites on Pine Creek and at the Hayton Millpond on the South Branch of the Manitowoc River in Wisconsin during 1993-95. PCB congener compositions were analyzed in the operationally defined dissolved phase, suspended particulate phase, and surficial bed sediments (0-2 centimeters depth) several times throughout the sampling period. The relative abundances of PCB congeners in the suspended particles and in surficial bed sediments were generally similar to each other and to a known Aroclor mixture (1254). PCB congener composites in the operationally defined dissolved phase were higher in the less chlorinated congeners in keeping with their lower hydrophobicity and higher predicted solubility relative to the more chlorinated congeners. Suspended particle-associated PCB concentrations exhibited two patterns: (1) a cyclical variation in spring and summer associated with algal growth, and (2) episodic increases associated with resuspension of bed sediments during storms. Computed total suspended-solids (TSS) load at the millpond outlet was as high as 920 tons over a 3-month period (June 30-Sept. 30, 1993). Annual TSS loads for the following two years were lower, 610 and 500 tons, respectively. Total PCB concentrations in the water column varied at the millpond outlet, ranging from 34 to 302 nanograms per liter, whereas concentrations upstream on Pine Creek were as high as 563 nanograms per liter. In general, 70 percent of PCB's in the water column were associated with suspended particles. The total congener-summation PCB (SPCB) concentration regression equation incorporated the universal soil loss coefficent to represent erosion of assumedly PCB-free sediment from fields upstream from the millpond. The SPCB load based on the regression relation was 3.4 kilograms during the 3-month high-flow interval (June 30-Sept. 30, 1993). Subsequent annual SPCB loads for the next two water years were 3.5 and 2.3 kilograms, respectively.

Stochastic modeling of total suspended solids (TSS) in urban areas during rain events.

PubMed

Rossi, Luca; Krejci, Vladimir; Rauch, Wolfgang; Kreikenbaum, Simon; Fankhauser, Rolf; Gujer, Willi

2005-10-01

The load of total suspended solids (TSS) is one of the most important parameters for evaluating wet-weather pollution in urban sanitation systems. In fact, pollutants such as heavy metals, polycyclic aromatic hydrocarbons (PAHs), phosphorous and organic compounds are adsorbed onto these particles so that a high TSS load indicates the potential impact on the receiving waters. In this paper, a stochastic model is proposed to estimate the TSS load and its dynamics during rain events. Information on the various simulated processes was extracted from different studies of TSS in urban areas. The model thus predicts the probability of TSS loads arising from combined sewer overflows (CSOs) in combined sewer systems as well as from stormwater in separate sewer systems in addition to the amount of TSS retained in treatment devices in both sewer systems. The results of this TSS model illustrate the potential of the stochastic modeling approach for assessing environmental problems.

Total mercury and methylmercury in high altitude surface snow from the French Alps.

PubMed

Marusczak, Nicolas; Larose, Catherine; Dommergue, Aurélien; Yumvihoze, Emmanuel; Lean, David; Nedjai, Rachid; Ferrari, Christophe

2011-09-01

Surface snow samples were collected weekly from the 31st of December 2008 to the 21st of June 2009 from Lake Bramant in the French Alps. Total mercury (THg), total dissolved mercury (THgD), methylmercury (MeHg) and particle distributions in surface snow were analyzed. Results showed that THg concentrations, MeHg concentrations and particle load increased with snow surface temperature, which is an indicator of rising temperatures as the season progresses. Significant correlations between MeHg and snow surface temperature and MeHg and total particles greater than 10 μm were observed. This suggests that the MeHg found in the snow originates from atmospheric deposition processes rather than in situ snowpack sources. This study suggests that an important post-winter atmospheric deposition of MeHg and THg occurs on summital zones of the French Alps and it is likely that this contamination originates from the surrounding valleys. Copyright © 2011 Elsevier B.V. All rights reserved.

Analysis of the Sediment Hydrograph of the alluvial deltas in the Apalachicola River, Florida

NASA Astrophysics Data System (ADS)

Daranpob, A.; Hagen, S.; Passeri, D.; Smar, D. E.

2011-12-01

Channel and alluvial characteristics in lowlands are the products of boundary conditions and driving forces. The boundary conditions normally include materials and land cover types, such as soil type and vegetation cover. General driving forces include discharge rate, sediment loadings, tides and waves. Deltas built up of river-transported sediment occur in depositional zones of the river mouth in flat terrains and slow currents. Total sediment load depends on two major abilities of the river, the river shear stress and capacity. The shear stress determines transport of a given sediment grain size, normally expressed as tractive force. The river capacity determines the total load or quantity of total sediments transported across a section of the river, generally expressed as the sediment loading rate. The shear stress and sediment loading rate are relatively easy to measure in the headwater and transfer zones where streams form a v-shape valley and the river begins to form defined banks compared to the deposition zone where rivers broaden across lower elevation landscapes creating alluvial forms such as deltas. Determinations of deposition and re-suspension of sediment in fluvial systems are complicated due to exerting tidal, wind, and wave forces. Cyclic forces of tides and waves repeatedly change the sediment transport and deposition rate spatially and temporally in alluvial fans. However, the influence decreases with water depth. Understanding the transport, deposition, and re-suspension of sediments in the fluvial zone would provide a better understanding of the morphology of landscape in lowland estuaries such as the Apalachicola Bay and its estuary systems. The Apalachicola River system is located in the Florida Panhandle. Shelf sedimentation process is not a strong influence in this region because it is protected by barrier islands from direct ocean forces of the Gulf of Mexico. This research explores the characteristic of suspended sediment loadings in fluvial zones of the Apalachicola River and its distributaries through field investigation and laboratory analysis of a series of total suspended solid (TSS) samples. Time-series TSS samples are collected at the alluvial zone. TSS and particle-size distribution analyses are performed to determine the TSS hydrograph and particle-size distribution of suspended solids. Relationships between the TSS hydrograph, discharge hydrograph, and tidal data provide a better understanding of the deposition and re-suspension of the fluvial system in the region. Total suspended particle-size distribution data are used to determine the deposition rate or diminishing rate of alluvial landform in the estuarine system. This dataset and analysis provide excellent information for future modeling work and wetland morphologic studies in the Apalachicola River and similar systems.

Aqueous extraction kinetics of soluble solids, phenolics and flavonoids from sage (Salvia fruticosa Miller) leaves.

PubMed

Torun, Mehmet; Dincer, Cuneyt; Topuz, Ayhan; Sahin-Nadeem, Hilal; Ozdemir, Feramuz

2015-05-01

In the present study, aqueous extraction kinetics of total soluble solids (TSS), total phenolic content (TPC) and total flavonoid content (TFC) from Salvia fruticosa leaves were investigated throughout 150 min. of extraction period against temperature (60-80 °C), particle size (2-8 mm) and loading percentage (1-4 %). The extract yielded 25 g/100 g TSS which contained 30 g/100 g TPC and 25 g/100 g TFC. The extraction data in time course fit with reversible first order kinetic model. All tested variables showed significant effect on the estimated kinetic parameters except equilibrium concentration. Increasing the extraction temperature resulted high extraction rate constants and equilibrium concentrations of the tested variables notably above 70 °C. By using the Arrhenius relationship, activation energy of the TSS, TPC and TFC were determined as 46.11 ± 5.61, 36.80 ± 3.12 and 33.52 ± 2.23 kj/mol, respectively. By decreasing the particle size, the extraction rate constants and diffusion coefficients exponentially increased whereas equilibrium concentrations did not change significantly. The equilibrium concentrations of the tested parameters showed linear behavior with increasing the loading percentage of the sage, however; the change in extraction rates did not show linear behavior due to submerging effect of 4 % loading.

High performance diesel oxidation catalysts using ultra-low Pt loading on titania nanowire array integrated cordierite honeycombs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoang, Son; Lu, Xingxu; Tang, Wenxiang

High performance of an ultra-low Pt loading diesel oxidation catalyst can be achieved by using a combination of novel nano-array structured support, precise control of ultrafine active Pt particles, and an addition of H 2 as a promoter into the exhausts. Highly stable mesoporous rutile TiO 2 nano-array was uniformly grown on three-dimensional (3-D) cordierite honeycomb monoliths using a solvothermal synthesis. Atomic layer deposition was employed for precise dispersion of ultrafine Pt particles (0.95 ± 0.24 nm) on TiO 2 nano-array with a Pt loading of 1.1 g/ft 3. Despite low Pt loading, the Pt/TiO 2 nano-array catalyst shows impressivemore » low-temperature oxidation reactivity, with the conversion of CO and total hydrocarbon (THC) reaching 50% at 224 and 285 °C, respectively, in the clean diesel combustion (CDC) simulated exhaust conditions. The excellent activity is attributed to the unique nano-array structure that promotes gas-solid interaction and ultra-small Pt particle dispersion that increase surface Pt atoms. We also demonstrate that addition of more H 2 into the exhaust can lower light-off temperature for CO and THC by up to ~60 °C and ~30 °C, respectively.« less

High performance diesel oxidation catalysts using ultra-low Pt loading on titania nanowire array integrated cordierite honeycombs

DOE PAGES

Hoang, Son; Lu, Xingxu; Tang, Wenxiang; ...

2017-11-15

High performance of an ultra-low Pt loading diesel oxidation catalyst can be achieved by using a combination of novel nano-array structured support, precise control of ultrafine active Pt particles, and an addition of H 2 as a promoter into the exhausts. Highly stable mesoporous rutile TiO 2 nano-array was uniformly grown on three-dimensional (3-D) cordierite honeycomb monoliths using a solvothermal synthesis. Atomic layer deposition was employed for precise dispersion of ultrafine Pt particles (0.95 ± 0.24 nm) on TiO 2 nano-array with a Pt loading of 1.1 g/ft 3. Despite low Pt loading, the Pt/TiO 2 nano-array catalyst shows impressivemore » low-temperature oxidation reactivity, with the conversion of CO and total hydrocarbon (THC) reaching 50% at 224 and 285 °C, respectively, in the clean diesel combustion (CDC) simulated exhaust conditions. The excellent activity is attributed to the unique nano-array structure that promotes gas-solid interaction and ultra-small Pt particle dispersion that increase surface Pt atoms. We also demonstrate that addition of more H 2 into the exhaust can lower light-off temperature for CO and THC by up to ~60 °C and ~30 °C, respectively.« less

Impact of pectin esterification on the antimicrobial activity of nisin-loaded pectin particles.

PubMed

Krivorotova, Tatjana; Staneviciene, Ramune; Luksa, Juliana; Serviene, Elena; Sereikaite, Jolanta

2017-01-01

The relationship between pectin structure and the antimicrobial activity of nisin-loaded pectin particles was examined. The antimicrobial activity of five different nisin-loaded pectin particles, i.e., nisin-loaded high methoxyl pectin, low methoxyl pectin, pectic acid, dodecyl pectin with 5.4 and 25% degree of substitution were tested in the pH range of 4.0-7.0 by agar-diffusion assay and agar plate count methods. It was found that the degree of esterification of carboxyl group of galacturonic acid in pectin molecule is important for the antimicrobial activity of nisin-loaded pectin particles. Nisin-loaded particles prepared using pectic acid or the pectin with low degree of esterification exhibit higher antimicrobial activity than nisin-loaded high methoxyl pectin particles. Pectins with free carboxyl groups or of low degree of esterification are the most suitable for particles preparation. Moreover, nisin-loaded pectin particles were active at close to neutral or neutral pH values. Therefore, they could be effectively applied for food preservation. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:245-251, 2017. © 2016 American Institute of Chemical Engineers.

Ternary nucleation as a mechanism for the production of diesel nanoparticles: experimental analysis of the volatile and hygroscopic properties of diesel exhaust using the volatilization and humidification tandem differential mobility analyzer.

PubMed

Meyer, N K; Ristovski, Z D

2007-11-01

The volatile and hygroscopic properties of diesel nanoparticles were simultaneously determined under a range of engine loads using the volatilization and humidification tandem differential mobility analyzer (VH-TDMA). Additionally, the VH-TDMA was used to measure changes in the hygroscopic behavior of the heterogeneously nucleated diesel nanoparticles as one or more semivolatile species were removed via thermal evaporation or decomposition. Particles produced at high loads exhibited high, dual-step volatility, while those particles produced at low loads were less volatile and exhibited continuous volatilization curves. The hygroscopic growth factor of the particles was shown to be load dependent with high-load particles exhibiting growth factors similar to that of ammonium sulfate. At 85% relative humidity, particles produced at moderate loads exhibited growth factors of approximately 1.1 while low-load particles were shown to be hydrophobic. Growth factors and volatilization temperatures measured for high-load particles clearly indicate that ternary nucleation is involved in particle formation.

Sediment transport, particle sizes, and loads in lower reaches of the Chippewa, Black and Wisconsin Rivers in Western Wisconsin

USGS Publications Warehouse

Rose, W.J.

1992-01-01

Average annual total-sediment load and the percentage transported as bedload were determined for a 10-year period (water years 1974-83)(October 1,1973-September 30, 1982). These loads and percentages were, respectively, 123,000 tons and 35 percent at Chippewa River near Caryville; 1,073,000 tons and 61 percent at Chippewa River at Durand; 940,000 tons and 44 percent at Chippewa River near Pepin; 277,000 tons and 43 percent at Black River near Galesville; and 558,000 tons and 49 percent at Wisconsin River at Muscoda.

Parking lot runoff quality and treatment efficiencies of a hydrodynamic-settling device in Madison, Wisconsin, 2005-6

USGS Publications Warehouse

Horwatich, Judy A.; Bannerman, Roger T.

2012-01-01

A hydrodynamic-settling device was installed in 2004 to treat stormwater runoff from a roof and parking lot located at the Water Utility Administration Building in Madison, Wis. The U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, the City of Madison, cities in the Waukesha Permit Group, Hydro International, Earth Tech, Inc., National Sanitation Foundation International, and the U.S. Environmental Protection Agency, monitored the device from November 2005 through September 2006 to evaluate it as part of the U.S. Environmental Protection Agency's Environmental Technology Verification Program. Twenty-three runoff events monitored for flow volume and water quality at the device's inlet and outlet were used to calculate the percentage of pollutant reduction for the device. The geometric mean concentrations of suspended sediment (SS), "adjusted" total suspended solids (TSS), total phosphorus (TP), dissolved phosphorus (DP), total recoverable zinc (TZn), and total recoverable copper (TCu) measured at the inlet were 107 mg/L (milligrams per liter), 92 mg/L, 0.17 mg/L, 0.05 mg/L, 38 μg/L (micrograms per liter), and 12 μg/L, respectively, and these concentrations are in the range of values observed in stormwater runoff from other parking lots in Wisconsin and Michigan. Efficiency of the settling device was calculated using the efficiency ratio and summation of loads (SOL) methods. Using the efficiency ratio method, the device reduced concentrations of SS, and DP, by 19, and 15, percent, respectively. Using the efficiency ratio method, the device increased "adjusted" TSS and TZn concentrations by 5 and 19, respectively. Bypass occurred for 3 of the 23 runoff events used in this assessment, and the bypass flow and water-quality concentrations were used to determine the efficiency of the bypass system. Concentrations of SS, "adjusted" TSS, and DP were reduced for the system by 18, 5, and 18, respectively; however, TZn increased by 5 percent. Some of the TSS concentrations were "adjusted" to add the particles that remained on the sieves during sample processing. The loads of SS, "adjusted" TSS, and DP were reduced using the SOL method for the settling device by 38, 9, and 19 percent, respectively, and TZn increased by 13 percent. For the bypass system, the loads of SS, "adjusted" TSS, and DP had percentage reductions of 39, 12, 22, respectively, however TZn increased by 4 percent. The SOL method produced percentage reductions for SS and 'adjusted" TSS that were twice those for the efficiency ratio method. Removing the two large runoff events on August 23 and 24, 2006, from the SOL calculation brought the reduction for SS down to 16 and increased "adjusted" TSS by 4 percent. The two large runoff events were anomalies in that the runoff volumes and dissolved solids concentrations were greatly increased by overflow from an adjacent recycling facility. The SOL method was used to determine the percentage of SS load reduction for six different particle sizes for both the settling device and bypass system. Essentially no load reduction was observed for particles less than 125 micrometers (μm) in diameter, and about a 90-percent reduction occurred for particle sizes greater than 250 μm in diameter. The large removal efficiencies for particle sizes greater than 250 μm in diameter were further supported by the fact that more than 80 percent of the particle sizes trapped in the sump were greater than 250 μm in diameter. These results support the claim by the manufacturer of achieving a large percentage load reduction for particle sizes greater than 250 μm in diameter.

Concentrations of major grass group 5 allergens in pollen grains and atmospheric particles: implications for hay fever and allergic asthma sufferers sensitized to grass pollen allergens.

PubMed

Schäppi, G F; Taylor, P E; Pain, M C; Cameron, P A; Dent, A W; Staff, I A; Suphioglu, C

1999-05-01

Grass pollen allergens are the most important cause of hay fever and allergic asthma during summer in cool temperate climates. Pollen counts provide a guide to hay fever sufferers. However, grass pollen, because of its size, has a low probability of entering the lower airways to trigger asthma. Yet, grass pollen allergens are known to be associated with atmospheric respirable particles. We aimed (1) to determine the concentration of group 5 major allergens in (a) pollen grains of clinically important grass species and (b) atmospheric particles (respirable and nonrespirable) and (2) to compare the atmospheric allergen load with clinical data to assess different risk factors for asthma and hay fever. We have performed a continuous 24 h sampling of atmospheric particles greater and lower than 7.2 microm in diameter during the grass pollen season of 1996 and 1997 (17 October 1996-16 January 1997) by means of a high volume cascade impactor at a height of about 15 m above ground in Melbourne. Using Western analysis, we assessed the reactivity of major timothy grass allergen Phl p 5 specific monoclonal antibody (MoAb) against selected pollen extracts. A MoAb-based ELISA was then employed to quantify Phl p 5 and cross-reactive allergens in pollen extracts and atmospheric particles larger and smaller than 7.2 microm. Phl p 5-specific MoAb detected group 5 allergens in tested grass pollen extracts, indicating that the ELISA employed here determines total group 5 allergen concentrations. On average, 0.05 ng of group 5 allergens were detectable per grass pollen grain. Atmospheric group 5 allergen concentrations in particles > 7.2 microm were significantly correlated with grass pollen counts (rs = 0.842, P < 0. 001). On dry days, 37% of the total group 5 allergen load, whereas upon rainfall, 57% of the total load was detected in respirable particles. After rainfall, the number of starch granule equivalents increased up to 10-fold; starch granule equivalent is defined as a hypothetical potential number of airborne starch granules based on known pollen count data. This indicates that rainfall tended to wash out large particles and contributed to an increase in respirable particles containing group 5 allergens by bursting of pollen grains. Four day running means of group 5 allergens in respirable particles and of asthma attendances (delayed by 2 days) were shown to be significantly correlated (P < 0.001). Here we present, for the first time, an estimation of the total group 5 allergen content in respirable and nonrespirable particles in the atmosphere of Melbourne. These results highlight the different environmental risk factors for hay fever and allergic asthma in patients, as on days of rainfall following high grass pollen count, the risk for asthma sufferers is far greater than on days of high pollen count with no associated rainfall. Moreover, rainfall may also contribute to the release of allergens from fungal spores and, along with the release of free allergen molecules from pollen grains, may be able to interact with other particles such as pollutants (i.e. diesel exhaust carbon particles) to trigger allergic asthma.

Continuous fluidized-bed contactor with recycle of sorbent

DOEpatents

Scott, Charles D.; Petersen, James N.; Davison, Brian H.

1996-01-01

A continuous fluidized-bed contactor containing sorbent particles is used to remove solutes from liquid solvents. As the sorbent particles, for example gel beads, sorb the solute, for example metal ion species, the sorbent particles tend to decrease in diameter. These smaller loaded sorbent particles rise to the top of the contactor, as larger sorbent particles remain at the bottom of the contactor as a result of normal hydraulic forces. The smaller loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. Alternatively, the loaded sorbent particles may also slightly increase in diameter, or exhibit no change in diameter but an increase in density. As a result of normal hydraulic forces the larger loaded sorbent particles fall to the bottom of the contactor. The larger loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor.

Continuous fluidized-bed contactor with recycle of sorbent

DOEpatents

Scott, C.D.; Petersen, J.N.; Davison, B.H.

1996-07-09

A continuous fluidized-bed contactor containing sorbent particles is used to remove solutes from liquid solvents. As the sorbent particles, for example gel beads, sorb the solute, for example metal ion species, the sorbent particles tend to decrease in diameter. These smaller loaded sorbent particles rise to the top of the contactor, and larger sorbent particles remain at the bottom of the contactor as a result of normal hydraulic forces. The smaller loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. Alternatively, the loaded sorbent particles may also slightly increase in diameter, or exhibit no change in diameter but an increase in density. As a result of normal hydraulic forces the larger loaded sorbent particles fall to the bottom of the contactor. The larger loaded sorbent particles are then recovered, regenerated, and reintroduced into the contactor. 8 figs.

Preparation and characterization of bee venom-loaded PLGA particles for sustained release.

PubMed

Park, Min-Ho; Jun, Hye-Suk; Jeon, Jong-Woon; Park, Jin-Kyu; Lee, Bong-Joo; Suh, Guk-Hyun; Park, Jeong-Sook; Cho, Cheong-Weon

2016-12-14

Bee venom-loaded poly(lactic-co-glycolic acid) (PLGA) particles were prepared by double emulsion-solvent evaporation, and characterized for a sustained-release system. Factors such as the type of organic solvent, the amount of bee venom and PLGA, the type of PLGA, the type of polyvinyl alcohol, and the emulsification method were considered. Physicochemical properties, including the encapsulation efficiency, drug loading, particle size, zeta-potential and surface morphology were examined by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The size of the bee venom-loaded PLGA particles was 500 nm (measured using sonication). Zeta-potentials of the bee venom-loaded PLGA particles were negative owing to the PLGA. FT-IR results demonstrated that the bee venom was completely encapsulated in the PLGA particles, indicated by the disappearance of the amine and amide peaks. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicated that the bee venom in the bee venom-loaded PLGA particles was intact. In vitro release of the bee venom from the bee venom-loaded PLGA particles showed a sustained-release profile over 1 month. Bee venom-loaded PLGA particles can help improve patients' quality of life by reducing the number of injections required.

Particle loading rates for HVAC filters, heat exchangers, and ducts.

PubMed

Waring, M S; Siegel, J A

2008-06-01

The rate at which airborne particulate matter deposits onto heating, ventilation, and air-conditioning (HVAC) components is important from both indoor air quality (IAQ) and energy perspectives. This modeling study predicts size-resolved particle mass loading rates for residential and commercial filters, heat exchangers (i.e. coils), and supply and return ducts. A parametric analysis evaluated the impact of different outdoor particle distributions, indoor emission sources, HVAC airflows, filtration efficiencies, coils, and duct system complexities. The median predicted residential and commercial loading rates were 2.97 and 130 g/m(2) month for the filter loading rates, 0.756 and 4.35 g/m(2) month for the coil loading rates, 0.0051 and 1.00 g/month for the supply duct loading rates, and 0.262 g/month for the commercial return duct loading rates. Loading rates are more dependent on outdoor particle distributions, indoor sources, HVAC operation strategy, and filtration than other considered parameters. The results presented herein, once validated, can be used to estimate filter changing and coil cleaning schedules, energy implications of filter and coil loading, and IAQ impacts associated with deposited particles. The results in this paper suggest important factors that lead to particle deposition on HVAC components in residential and commercial buildings. This knowledge informs the development and comparison of control strategies to limit particle deposition. The predicted mass loading rates allow for the assessment of pressure drop and indoor air quality consequences that result from particle mass loading onto HVAC system components.

Low modulus biomimetic microgel particles with high loading of hemoglobin.

PubMed

Chen, Kai; Merkel, Timothy J; Pandya, Ashish; Napier, Mary E; Luft, J Christopher; Daniel, Will; Sheiko, Sergei; DeSimone, Joseph M

2012-09-10

We synthesized extremely deformable red blood cell-like microgel particles and loaded them with bovine hemoglobin (Hb) to potentiate oxygen transport. With similar shape and size as red blood cells (RBCs), the particles were fabricated using the PRINT (particle replication in nonwetting templates) technique. Low cross-linking of the hydrogel resulted in very low mesh density for these particles, allowing passive diffusion of hemoglobin throughout the particles. Hb was secured in the particles through covalent conjugation of the lysine groups of Hb to carboxyl groups in the particles via EDC/NHS coupling. Confocal microscopy of particles bound to fluorescent dye-labeled Hb confirmed the uniform distribution of Hb throughout the particle interior, as opposed to the surface conjugation only. High loading ratios, up to 5 times the amount of Hb to polymer by weight, were obtained without a significant effect on particle stability and shape, though particle diameter decreased slightly with Hb conjugation. Analysis of the protein by circular dichroism (CD) spectroscopy showed that the secondary structure of Hb was unperturbed by conjugation to the particles. Methemoglobin in the particles could be maintained at a low level and the loaded Hb could still bind oxygen, as studied by UV-vis spectroscopy. Hb-loaded particles with moderate loading ratios demonstrated excellent deformability in microfluidic devices, easily deforming to pass through restricted pores half as wide as the diameter of the particles. The suspension of concentrated particles with a Hb concentration of 5.2 g/dL showed comparable viscosity to that of mouse blood, and the particles remained intact even after being sheared at a constant high rate (1000 1/s) for 10 min. Armed with the ability to control size, shape, deformability, and loading of Hb into RBC mimics, we will discuss the implications for artificial blood.

Low Modulus Biomimetic Microgel Particles with High Loading of Hemoglobin

PubMed Central

Chen, Kai; Merkel, Timothy J.; Pandya, Ashish; Napier, Mary E.; Luft, J. Christopher; Daniel, Will; Sheiko, Sergei

2012-01-01

We synthesized extremely deformable red blood cell-like microgel particles and loaded them with bovine hemoglobin (Hb) to potentiate oxygen transport. With similar shape and size as red blood cells (RBCs), the particles were fabricated using the PRINT® (Particle Replication In Non-wetting Templates) technique. Low crosslinking of the hydrogel resulted in very low mesh density for these particles, allowing passive diffusion of hemoglobin throughout the particles. Hb was secured in the particles through covalent conjugation of the lysine groups of Hb to carboxyl groups in the particles via EDC/NHS coupling. Confocal microscopy of particles bound to fluorescent dye-labeled Hb confirmed the uniform distribution of Hb throughout the particle interior, as opposed to the surface conjugation only. High loading ratios, up to 5 times the amount of Hb to polymer by weight, were obtained, without a significant effect on particle stability, shape, though particle diameter decreased slightly with Hb conjugation. Analysis of the protein by circular dichroism (CD) spectroscopy showed that the secondary structure of Hb was unperturbed by conjugation to the particles. Methemoglobin in the particles could be maintained at a low level and the loaded Hb could still bind oxygen as studied by UV-vis spectroscopy. Hb-loaded particles with moderate loading ratios demonstrated excellent deformability in microfluidic devices, easily deforming to pass through restricted pores half as wide as the diameter of the particles. The suspension of concentrated particles with Hb concentration of 5.2 g/dL showed comparable viscosity to that of mouse blood, and the particles remained intact even after being sheared at a constant high rate (1,000 1/s) for 10 min. Armed with the ability to control size, shape, deformability, and loading of Hb into RBC mimics, we will discuss the implications for artificial blood. PMID:22852860

Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.

NASA Astrophysics Data System (ADS)

Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

2006-12-01

The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized particles were between 50 and 300 nm, depending on engine operating conditions and particle composition. We will show that while the drastically reduced diesel PM emissions often render the PM filter measurements inadequate due to organic vapor artifacts SPLAT demonstrated its capability to provide real-time information on size and composition of individual diesel exhaust particles as function of engine operating conditions with better than 1 minute resolution.

Investigation of Anion-Exchange and Immunoaffinity Particle-Loaded Membranes for the Isolation of Charged Organic Analytes from Water

USGS Publications Warehouse

Dombrowski, T.R.; Wilson, G.S.; Thurman, E.M.

1998-01-01

Anion-exchange and immunoaffinity particle loaded membranes (PLMs) were investigated as a mechanism for the isolation of charged organic analytes from water. Kinetic properties determined theoretically included dynamic capacity, pressure drop (??P), residence and diffusion times (Tr, Td), and total membrane porosity (???T). These properties were confirmed through experimental evaluation, and the PLM method showed significant improvement over conventional solid-phase extraction (SPE) and ion-exchange formats. Recoveries of more than 90% were observed for a variety of test compounds at flow rates up to 70 mL/min (equipment-limited maximum flow rate). A fast-flow immunoaffinity column was developed using antibodies (Abs) attached to the PLMs. Reproducible recoveries (88% ?? 4%) were observed at flow rates up to 70 mL/min for the antibody (Ab)-loaded PLMs. Findings indicate increased selectivity over anion-exchange PLMs and conventional SPE or ion-exchange methods and rapid Ab-antigen binding rates given the excellent mass-transfer characteristics of the PLMs.

Characterization of aerosols and fibers emitted from composite materials combustion.

PubMed

Chivas-Joly, C; Gaie-Levrel, F; Motzkus, C; Ducourtieux, S; Delvallée, A; De Lagos, F; Nevé, S Le; Gutierrez, J; Lopez-Cuesta, J-M

2016-01-15

This work investigates the aerosols emitted during combustion of aircraft and naval structural composite materials (epoxy resin/carbon fibers and vinyl ester/glass fibers and carbon nanotubes). Combustion tests were performed at lab-scale using a modified cone calorimeter. The aerosols emitted have been characterized using various metrological devices devoted to the analysis of aerosols. The influence of the nature of polymer matrices, the incorporation of fibers and carbon nanotubes as well as glass reinforcements on the number concentration and the size distribution of airborne particles produced, was studied in the 5 nm-10 μm range. Incorporation of carbon fibers into epoxy resin significantly reduced the total particle number concentration. In addition, the interlaced orientation of carbon fibers limited the particles production compared to the composites with unidirectional one. The carbon nanotubes loading in vinyl ester resin composites influenced the total particles production during the flaming combustion with changes during kinetics emission. Predominant populations of airborne particles generated during combustion of all tested composites were characterized by a PN50 following by PN(100-500). Copyright © 2015 Elsevier B.V. All rights reserved.

Apparatus for blending small particles

DOEpatents

Bradley, R.A.; Reese, C.R.; Sease, J.D.

1975-08-26

An apparatus is described for blending small particles and uniformly loading the blended particles in a receptacle. Measured volumes of various particles are simultaneously fed into a funnel to accomplish radial blending and then directed onto the apex of a conical splitter which collects the blended particles in a multiplicity of equal subvolumes. Thereafter the apparatus sequentially discharges the subvolumes for loading in a receptacle. A system for blending nuclear fuel particles and loading them into fuel rod molds is described in a preferred embodiment. (auth)

Practical comparison of 2.7 microm fused-core silica particles and porous sub-2 microm particles for fast separations in pharmaceutical process development.

PubMed

Abrahim, Ahmed; Al-Sayah, Mohammad; Skrdla, Peter; Bereznitski, Yuri; Chen, Yadan; Wu, Naijun

2010-01-05

Fused-core silica stationary phases represent a key technological advancement in the arena of fast HPLC separations. These phases are made by fusing a 0.5 microm porous silica layer onto 1.7 microm nonporous silica cores. The reduced intra-particle flow path of the fused particles provides superior mass transfer kinetics and better performance at high mobile phase velocities, while the fused-core particles provide lower pressure than sub-2 microm particles. In this work, chromatographic performance of the fused-core particles (Ascentis Express) was investigated and compared to that of sub-2 microm porous particles (1.8 microm Zorbax Eclipse Plus C18 and 1.7 microm Acquity BEH C18). Specifically, retention, selectivity, and loading capacity were systematically compared for these two types of columns. Other chromatographic parameters such as efficiency and pressure drop were also studied. Although the fused-core column was found to provide better analyte shape selectivity, both columns had similar hydrophobic, hydrogen bonding, total ion-exchange, and acidic ion-exchange selectivities. As expected, the retention factors and sample loading capacity on the fused-core particle column were slightly lower than those for the sub-2 microm particle column. However, the most dramatic observation was that similar efficiency separations to the sub-2 microm particles could be achieved using the fused-core particles, without the expense of high column back pressure. The low pressure of the fused-core column allows fast separations to be performed routinely on a conventional LC system without significant loss in efficiency or resolution. Applications to the HPLC impurity profiling of drug substance candidates were performed using both types of columns to validate this last point.

The effects of particle loading on turbulence structure and modelling

NASA Technical Reports Server (NTRS)

Squires, Kyle D.; Eaton, J. K.

1989-01-01

The objective of the present research was to extend the Direct Numerical Simulation (DNS) approach to particle-laden turbulent flows using a simple model of particle/flow interaction. The program addressed the simplest type of flow, homogeneous, isotropic turbulence, and examined interactions between the particles and gas phase turbulence. The specific range of problems examined include those in which the particle is much smaller than the smallest length scales of the turbulence yet heavy enough to slip relative to the flow. The particle mass loading is large enough to have a significant impact on the turbulence, while the volume loading was small enough such that particle-particle interactions could be neglected. Therefore, these simulations are relevant to practical problems involving small, dense particles conveyed by turbulent gas flows at moderate loadings. A sample of the results illustrating modifications of the particle concentration field caused by the turbulence structure is presented and attenuation of turbulence by the particle cloud is also illustrated.

Oxidized Porous Silicon Particles Covalently Grafted with Daunorubicin as a Sustained Intraocular Drug Delivery System

PubMed Central

Chhablani, Jay; Nieto, Alejandra; Hou, Huiyuan; Wu, Elizabeth C.; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

2013-01-01

Purpose. To test the feasibility of covalent loading of daunorubicin into oxidized porous silicon (OPS) and to evaluate the ocular properties of sustained delivery of daunorubicin in this system. Methods. Porous silicon was heat oxidized and chemically functionalized so that the functional linker on the surface was covalently bonded with daunorubicin. The drug loading rate was determined by thermogravimetric analysis. Release of daunorubicin was confirmed in PBS and excised rabbit vitreous by mass spectrometry. Daunorubicin-loaded OPS particles (3 mg) were intravitreally injected into six rabbits, and ocular properties were evaluated through ophthalmic examinations and histology during a 3-month study. The same OPS was loaded with daunorubicin using physical adsorption and was evaluated similarly as a control for the covalent loading. Results. In the case of covalent loading, 67 ± 10 μg daunorubicin was loaded into each milligram of the particles while 27 ± 10 μg/mg particles were loaded by physical adsorption. Rapid release of daunorubicin was observed in both PBS and excised vitreous (∼75% and ∼18%) from the physical adsorption loading, while less than 1% was released from the covalently loaded particles. Following intravitreal injection, the covalently loaded particles demonstrated a sustained degradation of OPS with drug release for 3 months without evidence of toxicity; physical adsorption loading revealed a complete release within 2 weeks and localized retinal toxicity due to high daunorubicin concentration. Conclusions. OPS with covalently loaded daunorubicin demonstrated sustained intravitreal drug release without ocular toxicity, which may be useful to inhibit unwanted intraocular proliferation. PMID:23322571

Predicting the Effects of Powder Feeding Rates on Particle Impact Conditions and Cold Spray Deposited Coatings

NASA Astrophysics Data System (ADS)

Ozdemir, Ozan C.; Widener, Christian A.; Carter, Michael J.; Johnson, Kyle W.

2017-10-01

As the industrial application of the cold spray technology grows, the need to optimize both the cost and the quality of the process grows with it. Parameter selection techniques available today require the use of a coupled system of equations to be solved to involve the losses due to particle loading in the gas stream. Such analyses cause a significant increase in the computational time in comparison with calculations with isentropic flow assumptions. In cold spray operations, engineers and operators may, therefore, neglect the effects of particle loading to simplify the multiparameter optimization process. In this study, two-way coupled (particle-fluid) quasi-one-dimensional fluid dynamics simulations are used to test the particle loading effects under many potential cold spray scenarios. Output of the simulations is statistically analyzed to build regression models that estimate the changes in particle impact velocity and temperature due to particle loading. This approach eases particle loading optimization for more complete analysis on deposition cost and time. The model was validated both numerically and experimentally. Further numerical analyses were completed to test the particle loading capacity and limitations of a nozzle with a commonly used throat size. Additional experimentation helped document the physical limitations to high-rate deposition.

Endocytotic potential governs magnetic particle loading in dividing neural cells: studying modes of particle inheritance

PubMed Central

Tickle, Jacqueline A; Jenkins, Stuart I; Polyak, Boris; Pickard, Mark R; Chari, Divya M

2016-01-01

Aim: To achieve high and sustained magnetic particle loading in a proliferative and endocytotically active neural transplant population (astrocytes) through tailored magnetite content in polymeric iron oxide particles. Materials & methods: MPs of varying magnetite content were applied to primary-derived rat cortical astrocytes ± static/oscillating magnetic fields to assess labeling efficiency and safety. Results: Higher magnetite content particles display high but safe accumulation in astrocytes, with longer-term label retention versus lower/no magnetite content particles. Magnetic fields enhanced loading extent. Dynamic live cell imaging of dividing labeled astrocytes demonstrated that particle distribution into daughter cells is predominantly ‘asymmetric’. Conclusion: These findings could inform protocols to achieve efficient MP loading into neural transplant cells, with significant implications for post-transplantation tracking/localization. PMID:26785794

Mercury concentrations and loads in a large river system tributary to San Francisco Bay, California, USA

USGS Publications Warehouse

David, N.; McKee, L.J.; Black, F.J.; Flegal, A.R.; Conaway, C.H.; Schoellhamer, D.H.; Ganju, N.K.

2009-01-01

In order to estimate total mercury (HgT) loads entering San Francisco Bay, USA, via the Sacramento-San Joaquin River system, unfiltered water samples were collected between January 2002 and January 2006 during high flow events and analyzed for HgT. Unfiltered HgT concentrations ranged from 3.2 to 75 ng/L and showed a strong correlation (r2 = 0.8, p < 0.001, n = 78) to suspended sediment concentrations (SSC). During infrequent large floods, HgT concentrations relative to SSC were approximately twice as high as observed during smaller floods. This difference indicates the transport of more Hg-contaminated particles during high discharge events. Daily HgT loads in the Sacramento-San Joaquin River at Mallard Island ranged from below the limit of detection to 35 kg. Annual HgT loads varied from 61 ?? 22 kg (n = 5) in water year (WY) 2002 to 470 ?? 170 kg (n = 25) in WY 2006. The data collected will assist in understanding the long-term recovery of San Francisco Bay from Hg contamination and in implementing the Hg total maximum daily load, the long-term cleanup plan for Hg in the Bay. ?? 2009 SETAC.

Sediment characteristics in the San Antonio River Basin downstream from San Antonio, Texas, and at a site on the Guadalupe River downstream from the San Antonio River Basin, 1966-2013

USGS Publications Warehouse

Crow, Cassi L.; Banta, J. Ryan; Opsahl, Stephen P.

2014-01-01

San Antonio and surrounding municipalities in Bexar County, Texas, are in a rapidly urbanizing region in the San Antonio River Basin. The U.S. Geological Survey, in cooperation with the San Antonio River Authority and the Texas Water Development Board, compiled historical sediment data collected between 1996 and 2004 and collected suspended-sediment and bedload samples over a range of hydrologic conditions in the San Antonio River Basin downstream from San Antonio, Tex., and at a site on the Guadalupe River downstream from the San Antonio River Basin during 2011–13. In the suspended-sediment samples collected during 2011–13, an average of about 94 percent of the particles was less than 0.0625 millimeter (silt and clay sized particles); the 50 samples for which a complete sediment-size analysis was performed indicated that an average of about 69 percent of the particles was less than 0.002 millimeter. In the bedload samples collected during 2011–13, an average of 51 percent of sediment particles was sand-sized particles in the 0.25–0.5 millimeter-size range. In general, the loads calculated from the samples indicated that bedload typically composed less than 1 percent of the total sediment load. A least-squares log-linear regression was developed between suspended-sediment concentration and instantaneous streamflow and was used to estimate daily mean suspended-sediment loads based on daily mean streamflow. The daily mean suspended-sediment loads computed for each of the sites indicated that during 2011–12, the majority of the suspended-sediment loads originated upstream from the streamflow-gaging station on the San Antonio River near Elmendorf, Tex. A linear regression relation was developed between turbidity and suspended-sediment concentration data collected at the San Antonio River near Elmendorf site because the high-resolution data can facilitate understanding of the complex suspended-sediment dynamics over time and throughout the river basin.

Process-based modelling of phosphorus transformations and retention in global rivers

NASA Astrophysics Data System (ADS)

Vilmin, Lauriane; Mogollon, Jose; Beusen, Arthur; Bouwman, Lex

2016-04-01

Phosphorus (P) plays a major role in the biogeochemical functioning of aquatic systems. It typically acts as the limiting nutrient for primary productivity in freshwater bodies, and thus the increase in anthropogenic P loads during the XXth century has fuelled the eutrophication of these systems. Total P retention in global rivers has also escalated over this timeframe as demonstrated via a global model that implements the spiralling method at a spatial resolution of 0.5° (IMAGE-GNM, Beusen et al., 2015). Here, we refine this coupled hydrological - nutrient model by including mechanistic biogeochemical interactions that govern the P cycle. Special attention is paid to the representation of particle processes (i.e. particle loading, sedimentation and erosion), which play a major role in P transport and accumulation in aquatic systems. Our preliminary results are compared to measurements of suspended sediments, total P and orthophosphates in selected river basins. Initial model results show that P concentrations are particularly sensitive to particulate load distribution in the river network within a grid cell. This novel modelling approach will eventually allow a better assessment of the amounts of different forms of P (organic P, soluble reactive P, and particulate inorganic P), of P transformation rates and retention in inland waters. References Beusen, A.H.W., Van Beek, L.P.H., Bouwman, A.F., Mogollón, J.M., Middelburg, J.J. 2015. Coupling global models for hydrology and nutrient loading to simulate nitrogen and phosphorus retention in surface water - description of the IMAGE-GNM and analysis of performance. Geosci. Model Dev. 8, 4045-4067

Agricultural runoff pollution control by a grassed swales coupled with wetland detention ponds system: a case study in Taihu Basin, China.

PubMed

Zhao, Jinhui; Zhao, Yaqian; Zhao, Xiaoli; Jiang, Cheng

2016-05-01

The performance of a field grassed swales (GSs) coupled with wetland detention ponds (WDPs) system was monitored under four typical rainfall events to assess its effectiveness on agricultural runoff pollution control in Taihu Basin, China. The results indicated that suspended solids (SS) derived from the flush process has significant influence on pollution loads in agricultural runoff. Determination of first flush effect (FFE) indicated that total suspended solids (TSS) and total phosphorus (TP) exhibited moderate FFE, while chemical oxygen demand (COD) and total nitrogen (TN) showed weak FFE. Average removal efficiencies of 83.5 ± 4.5, 65.3 ± 6.8, 91.6 ± 3.8, and 81.3 ± 5.8 % for TSS, COD, TN, and TP were achieved, respectively. The GSs played an important role in removing TSS and TP and acted as a pre-treatment process to prevent clogging of the subsequent WDPs. Particle size distributions (PSDs) analysis indicated that coarse particles larger than 75 μm accounted for 80 % by weight of the total particles in the runoff. GSs can effectively reduce coarse particles (≥75 μm) in runoff, while its removal efficiency for fine particles (<75 μm) was low, even minus results being recorded, especially for particles smaller than 25 μm. The length of GSs is a key factor in its performance. The WDPs can remove particles of all sizes by sedimentation. In addition, WDPs can improve water quality due to their buffering and dilution capacity during rainfall as well as their water purification ability during dry periods. Overall, the ecological system of GSs coupled with WDPs is an effective system for agricultural runoff pollution control.

Contribution of different sources to the pollution of wet weather flows in combined sewers.

PubMed

Gromaire, M C; Garnaud, S; Saad, M; Chebbo, G

2001-02-01

Experiments performed on "Marais" catchment, in central Paris, aimed to follow up the quality of wet weather flows from the entry to the exit of a combined sewer network. SS, VSS, COD, BOD5, Cd, Cu, Pb, Zn concentrations were measured for an important number of rain events in roof, yard, street runoff, as well as in dry and wet weather flows at the catchment outlet. Mass entry-exit totals, at the scale of the catchment, were calculated over 31 rain events in order to evaluate the contribution of different types of runoff, of sanitary sewage and of sewer sediments to the total wet weather pollutant loads at the catchment outlet. The erosion of in-sewer pollutant stocks was found to be the main source of particles and of organic matter in wet weather flows, whereas heavy metal loads mainly originated from roof runoff, due to the corrosion of metallic roofs. Particles eroded inside the sewer during rain events were found to be quite different from the particles constituting the main part of sewer sediments: they are organic and biodegradable, with rather important settling velocities and seem to accumulate during dry weather periods. A change of the chemical form of heavy metals was noticed during the transport in the sewer and it is suspected that a fraction of the dissolved metals from the runoff is adsorbed on sewer sediments.

Methodology and significance of studies of atmospheric deposition in highway runoff

USGS Publications Warehouse

Colman, John A.; Rice, Karen C.; Willoughby, Timothy C.

2001-01-01

Atmospheric deposition and the processes that are involved in causing and altering atmospheric deposition in relation to highway surfaces and runoff were evaluated nationwide. Wet deposition is more easily monitored than dry deposition, and data on wet deposition are available for major elements and water properties (constituents affecting acid deposition) from the inter-agency National Atmospheric Deposition Program/ National Trends Network (NADP/NTN). Many trace constituents (metals and organic compounds) of interest in highway runoff loads, however, are not included in the NADP/NTN. Dry deposition, which constitutes a large part of total atmospheric deposition for many constituents in highway runoff loads, is difficult to monitor accurately. Dry-deposition rates are not widely available.Many of the highway-runoff investigations that have addressed atmospheric-deposition sources have had flawed investigative designs or problems with methodology. Some results may be incorrect because of reliance on time-aggregated data collected during a period of changing atmospheric emissions. None of the investigations used methods that could accurately quantify the part of highway runoff load that can be attributed to ambient atmospheric deposition. Lack of information about accurate ambient deposition rates and runoff loads was part of the problem. Samples collected to compute the rates and loads were collected without clean-sampling methods or sampler protocols, and without quality-assurance procedures that could validate the data. Massbudget calculations comparing deposition and runoff did not consider loss of deposited material during on-highway processing. Loss of deposited particles from highway travel lanes could be large, as has been determined in labeled particle studies, because of resuspension caused by turbulence from passing traffic. Although a cause of resuspension of large particles, traffic turbulence may increase the rate of deposition for small particles and gases by impaction, especially during precipitation periods.Ultimately, traffic and road maintenance may be determined to be the source of many constituents measured in highway runoff previously attributed to ambient atmospheric deposition. An investigative design using tracers of ambient deposition that are not present in highway traffic sources could determine conclusively what fraction of highway runoff load is contributed by ambient atmospheric deposition.

Fast particles in a steady-state compact FNS and compact ST reactor

NASA Astrophysics Data System (ADS)

Gryaznevich, M. P.; Nicolai, A.; Buxton, P.

2014-10-01

This paper presents results of studies of fast particles (ions and alpha particles) in a steady-state compact fusion neutron source (CFNS) and a compact spherical tokamak (ST) reactor with Monte-Carlo and Fokker-Planck codes. Full-orbit simulations of fast particle physics indicate that a compact high field ST can be optimized for energy production by a reduction of the necessary (for the alpha containment) plasma current compared with predictions made using simple analytic expressions, or using guiding centre approximation in a numerical code. Alpha particle losses may result in significant heating and erosion of the first wall, so such losses for an ST pilot plant have been calculated and total and peak wall loads dependence on the plasma current has been studied. The problem of dilution has been investigated and results for compact and big size devices are compared.

Source identification analysis for the airborne bacteria and fungi using a biomarker approach

NASA Astrophysics Data System (ADS)

Lee, Alex K. Y.; Lau, Arthur P. S.; Cheng, Jessica Y. W.; Fang, Ming; Chan, Chak K.

Our recent studies have reported the feasibility of employing the 3-hydoxy fatty acids (3-OH FAs) and ergosterol as biomarkers to determine the loading of the airborne endotoxin from the Gram-negative bacteria and fungal biomass in atmospheric aerosols, respectively [Lee, A.K.Y., Chan, C.K., Fang, K., Lau, A.P.S., 2004. The 3-hydroxy fatty acids as biomarkers for quantification and characterization of endotoxins and Gram-negative bacteria in atmospheric aerosols in Hong Kong. Atmospheric Environment 38, 6807-6317; Lau, A.P.S., Lee, A.K.Y., Chan, C.K., Fang, K., 2006. Ergosterol as a biomarker for the quantification of the fungal biomass in atmospheric aerosols. Atmospheric Environment 40, 249-259]. These quantified biomarkers do not, however, provide information on their sources. In this study, the year-long dataset of the endotoxin and ergosterol measured in Hong Kong was integrated with the common water-soluble inorganic ions for source identification through the principal component analysis (PCA) and backward air mass trajectory analysis. In the coarse particles (PM 2.5-10), the bacterial endotoxin is loaded in the same factor group with Ca 2+ and accounted for about 20% of the total variance of the PCA. This implies the crustal origin for the airborne bacterial assemblage. The fungal ergosterol in the coarse particles (PM 2.5-10) had by itself loaded in a factor group of 10.8% of the total variance in one of the sampling sites with large area of natural vegetative coverage. This suggests the single entity nature of the fungal spores and their independent emission to the ambient air upon maturation of their vegetative growth. In the fine particles (2.0) in the fine particles of the continental air masses imply the microbial source from activities related to biomass burning and industries from the north. The low K +/Na + ratios (1.2-1.4) in the fine particles of the mixed air masses suggest microbial sources from the local and regional indoor environment through kitchen emissions and the re-suspension of the road dust due to vehicular exhausts.

Quercetagetin-Loaded Zein-Propylene Glycol Alginate Ternary Composite Particles Induced by Calcium Ions: Structure Characterization and Formation Mechanism.

PubMed

Sun, Cuixia; Wei, Yang; Li, Ruirui; Dai, Lei; Gao, Yanxiang

2017-05-17

The complexation of zein and propylene glycol alginate (PGA) was confirmed to improve the entrapment efficiency and loading capacity of quercetagetin (Q) in our previous study. The present work focused on the influence and induction mechanism of calcium ions on structures of Q-loaded zein-PGA ternary composite particles. The incorporation of Ca 2+ resulted in the formation of aggregates with a large dimension between zein particles, led to obvious conformational, secondary, and tertiary structural changes of zein, and caused the disappearance of crystalline structure of zein. PGA exhibited a fine filamentous network structure and became much thicker and stronger in the presence of Ca 2+ . The presence of Q promoted the affinity and binding capacity of Ca 2+ to zein and PGA. An interwoven network structure with enhanced firmness and density was observed in Q-loaded zein-PGA composite particles, leading to improved thermal stability. Three potential mechanisms were proposed to explain the structural characteristics induced by Ca 2+ , including particle-particle collision for zein particles, chain-chain association for PGA molecules, and simultaneous cross-linking coupled with aggregating for Q-loaded zein-PGA composite particles.

Ultrafine particle concentration and new particle formation in a coastal arid environment

NASA Astrophysics Data System (ADS)

Alfoldy, Balint; Kotob, Mohamed; Obbard, Jeffrey P.

2017-04-01

Arid environments can be generally characterised by high coarse aerosol load due to the wind-driven erosion of the upper earth crust (i.e. Aeolian dust). On the other hand, anthropogenic activities and/or natural processes also generate significant numbers of particles in the ultrafine size range. Ultrafine particles (also referred as nano-particles) is considered as aerosol particles with the diameter less than 100 nm irrespectively their chemical composition. Due to their small size, these particles represent negligible mass portion in the total atmospheric particulate mass budget. On the other hand, these particles represent the majority of the total particle number budget and have the major contribution in the total aerosol surface distribution. Ultrafine particles are characterised by high mobility (diffusion) and low gravitational settling velocity. Consequently, these particles can be transported long distances and their atmospheric lifetime is relatively high (i.e. in the Accumulation Mode). Ultrafine particles play important role in the atmosphere as they take part in the atmospheric chemistry (high surface), impact the climate (sulphate vs. black carbon), and implies significant health effects due to their deep lung penetration and high mobility in the body. The Atmospheric Laboratory of Qatar University is conducting real-time monitoring of ultrafine particles and regularly taking aerosol samples for chemical analysis at the university campus. In this paper, recent results are presented regarding the size distribution and chemical composition of the ultrafine aerosol particles. Based on the concentration variation in time, sources of ultrafine particles can be clearly separated from the sources of fine or coarse particles. Several cases of new particle formation events have been observed and demonstrated in the paper, however, the precursors of the secondary aerosol particles are still unknown. Literature references suggest that among the sulphuric acid, iodine molecules can also play important role in new particle formation at coastal environments. Chemical analysis of size-segregated aerosol samples demonstrates that sulphate aerosol has a mean diameter at 300 nm that can be the Accumulation Mode of the previously nucleated sulphate particles. The mean diameter of black carbon particles was found at 180 nm. The new particle formation events were detected under 10 nm and particle concentration can reach up to 1.8x105 cm^-3 during severe events. The results demonstrate the significant natural and/or anthropogenic contribution of ultrafine particles to the total aerosol budget in an arid, coastal environment.

Marginal bed load transport in a gravel bed stream, Sagehen Creek, California

USGS Publications Warehouse

Andrews, E.D.

1994-01-01

Marginal bed load transport describes the condition when relatively few bed particles are moving at any time. Bed particles resting in the shallowest bed pockets will move when the dimensionless shear stress т* exceeds a value of about 0.020. As т* increases, the number of bed particles moving increases. Significant motion of bed particles, i.e., when a substantial fraction of the bed particles are moving, occurs when т* exceeds a value of about 0.060. Thus marginal bed load transport occurs over the domain 0.020 < т* < 0.060. Marginal bed load transport rates and associated hydraulic characteristics of Sagehen Creek, a small mountain gravel bed stream, were measured on 55 days at discharges ranging from slightly less than one half of the bank-full discharge to more than 4 times the bank-full discharge. Dimensionless shear stress varied from 0.032 to 0.042, and bed particles as large as the 80th percentile of the bed surface were transported. The relation between reference dimensionless shear stress and relative particle protrusion for Sagehen Creek was determined by varying т*ri to obtain the best fit of the Parker bed load function to the measured transport rates. During the period of record (water years 1954–1991), the mean annual quantity of bed load transported past the Sagehen Creek gage was 24.7 tons. Forty-seven percent of all bed load transported during the 38 years of record occurred in just 6 years. During 10 of the 38 years of record, essentially no bed load was transported. The median diameter of bed load was 26 mm, compared to 58 mm in the surface bed material.

Carrier characteristics influence the kinetics of passive drug loading into lipid nanoemulsions.

PubMed

Göke, Katrin; Bunjes, Heike

2018-05-01

Passive loading as a novel screening approach is a material-saving tool for the efficient selection of a suitable colloidal lipid carrier system for poorly water soluble drug candidates. This method comprises incubation of preformed carrier systems with drug powder and subsequent determination of the resulting drug load of the carrier particles after removal of excess drug. For reliable routine use and to obtain meaningful loading results, information on the kinetics of the process is required. Passive loading proceeds via a dissolution-diffusion-based mechanism, where drug surface area and drug water solubility are key parameters for fast passive loading. While the influence of the drug characteristics is mostly understood, the influence of the carrier characteristics remains unknown. The aim of this study was to examine how the lipid nanocarriers' characteristics, i.e. the type of lipid, the lipid content and the particle size, influence the kinetics of passive loading. Fenofibrate was used as model drug and the loading progress was analyzed by UV spectroscopy. The saturation solubility in the nanocarrier particles, i.e. the lipid type, did not influence the passive loading rate constant. Low lipid content in the nanocarrier and a small nanocarrier particle size both increased passive loading speed. Both variations increase the diffusivity of the nanocarrier particles, which is the primary cause for fast loading at these conditions: The quicker the carrier particles diffuse, the higher is the speed of passive loading. The influence of the diffusivity of the lipid nanocarriers and the effect of drug dissolution rate were included in an overall mechanistic model developed for similar processes (A. Balakrishnan, B.D. Rege, G.L. Amidon, J.E. Polli, Surfactant-mediated dissolution: contributions of solubility enhancement and relatively low micelle diffusivity, J. Pharm. Sci. 93 (2004) 2064-2075). The resulting mechanistic model gave a good estimate of the speed of passive loading in nanoemulsions. Whilst the drug's characteristics - apart from drug surface area - are basically fixed, the lipid nanocarriers can be customized to improve passive loading speed, e.g. by using small nanocarrier particles. The knowledge of the loading mechanism now allows the use of passive loading for the straightforward, material-saving selection of suitable lipid drug nanocarriers. Copyright © 2017 Elsevier B.V. All rights reserved.

Incomplete Loading of Sodium Lauryl Sulfate and Fasted State Simulated Intestinal Fluid Micelles Within the Diffusion Layers of Dispersed Drug Particles During Dissolution.

PubMed

Galipeau, Kendra; Socki, Michael; Socia, Adam; Harmon, Paul A

2018-01-01

Poorly water soluble drug candidates have been common in developmental pipelines over the last several decades. This has fueled considerable research around understanding how bile salt and model micelles can improve drug particle dissolution rates and human drug exposure levels. However, in the pharmaceutical context only a single mechanism of how micelles load solute has been assumed, that being the direct loading mechanism put forth by Cussler and coworkers (Am Inst Chem Eng J. 1976;22(6):1006-1012) 40 years ago. In this model, micelles load at the particle surface and will be loaded to their equilibrium loading values. More recently, Kumar and Gandhi and coworkers (Langmuir. 2003;19:4014-4026) developed a comprehensive theory of micelle solubilization which also features an indirect loading mechanism which they argue should operate in ionic surfactant systems. In this mechanism, micelles cannot directly load at the solute particle surface and thus may not reach equilibrium loading values within the particle diffusion layer. In this work, we endeavor to understand if the indirect micelle loading mechanism represents a plausible description in the pharmaceutical context. The overall data in SLS and FaSSIF systems obtained here, as well as several other previously published datasets, can be described by the indirect micelle loading mechanism. Implications for pharmaceutical development of poorly soluble compounds are discussed. Copyright © 2018. Published by Elsevier Inc.

Superficially porous particles columns for super fast HPLC separations.

PubMed

Ali, Imran; Al-Othman, Zeid A; Al-Za'abi, Mohammed

2012-08-01

Superficially porous silica particles columns (SPSPCs) are manufactured by different companies. The most common have the brand names Halo, Ascentis Express and Kinetex. These columns provide super fast, sharp peaks and moderate sample loading and back pressure. These are available in different chemistries such as C₈, C₁₈, RP Amide and Hilic. Normally, the silica gel particles have 2.7 and 1.7 µm total and inner solid core diameters with 0.5 µm thick outer porous layer, 90 Å pore size and 150 m²/g surface area. They have been used for the separation and identification of low and high molecular weight compounds. The present article describes the state of the art of superficially porous silica particles based columns with special emphasis on their structures, mechanisms of separation, applications and comparison. Copyright © 2012 John Wiley & Sons, Ltd.

Coupled reactions on bioparticles: Stereoselective reduction with cofactor regeneration on PhaC inclusion bodies.

PubMed

Spieler, Valerie; Valldorf, Bernhard; Maaß, Franziska; Kleinschek, Alexander; Hüttenhain, Stefan H; Kolmar, Harald

2016-07-01

Chiral alcohols are important building blocks for specialty chemicals and pharmaceuticals. The production of chiral alcohols from ketones can be carried out stereo selectively with alcohol dehydrogenases (ADHs). To establish a process for cost-effective enzyme immobilization on solid phase for application in ketone reduction, we used an established enzyme pair consisting of ADH from Rhodococcus erythropolis and formate dehydrogenase (FDH) from Candida boidinii for NADH cofactor regeneration and co-immobilized them on modified poly-p-hydroxybutyrate synthase (PhaC)-inclusion bodies that were recombinantly produced in Escherichia coli cells. After separate production of genetically engineered and recombinantly produced enzymes and particles, cell lysates were combined and enzymes endowed with a Kcoil were captured on the surface of the Ecoil presenting particles due to coiled-coil interaction. Enzyme-loaded particles could be easily purified by centrifugation. Total conversion of 4'-chloroacetophenone to (S)-4-chloro-α-methylbenzyl alcohol could be accomplished using enzyme-loaded particles, catalytic amounts of NAD(+) and formate as substrates for FDH. Chiral GC-MS analysis revealed that immobilized ADH retained enantioselectivity with 99 % enantiomeric excess. In conclusion, this strategy may become a cost-effective alternative to coupled reactions using purified enzymes. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and properties of inhalable nanocomposite particles for treatment of lung cancer.

PubMed

Tomoda, Keishiro; Ohkoshi, Takumi; Hirota, Keiji; Sonavane, Ganeshchandra S; Nakajima, Takehisa; Terada, Hiroshi; Komuro, Masahito; Kitazato, Kenji; Makino, Kimiko

2009-07-01

Nanoparticles have widely been studied in drug delivery research for targeting and controlled release. The aim of this article is application of nanoparticles as an inhalable agent for treatment of lung cancer. To deposit effectively deep the particles in the lungs, the PLGA nanoparticles loaded with the anticancer drug 6-{[2-(dimethylamino)ethyl]amino}-3-hydroxyl-7H-indeno[2,1-c]quinolin-7-one dihydrochloride (TAS-103) were prepared in the form of nanocomposite particles. The nanocomposite particles consist of the complex of drug-loaded nanoparticles and excipients. In this study, the anticancer effects of the nanocomposite particles against the lung cancer cell line A549. Also, the concentration of TAS-103 in blood and lungs were determined after administration of the nanocomposite particles by inhalation to rats. TAS-103-loaded PLGA nanoparticles were prepared with 5% and 10% of loading ratio by spray drying method with trehalose as an excipient. The 5% drug-loaded nanocomposite particles were more suitable for inhalable agent because of the sustained release of TAS-103 and higher FPF value. Cytotoxicity of nanocomposite particles against A549 cells was higher than that of free drug. When the nanocomposite particles were administered in rats by inhalation, drug concentration in lung was much higher than that in plasma. Furthermore, drug concentration in lungs administered by inhalation of nanocomposite particles was much higher than that after intravenous administration of free drug. From these results, the nanocomposite particle systems could be promising for treatment of lung cancer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Niranjan D.; Hudspeth, Matthew; Claus, Ben

Granular materials are widely used to resist impact and blast. Under these dynamic loadings, the constituent particles in the granular system fracture. To study the fracture mechanisms in brittle particles under dynamic compressive loading, a high speed X-ray phase contrast imaging setup was synchronized with a Kolsky bar apparatus. Controlled compressive loading was applied on two contacting particles using the Kolsky bar apparatus and fracture process was captured using the high speed X-ray imaging setup. Five different particles were investigated: soda-lime glass, polycrystalline silica (silicon dioxide), polycrystalline silicon, barium titanate glass, and yttrium stabilized zirconia. For both soda lime glassmore » and polycrystalline silica particles, one of the particles fragmented explosively, thus breaking into many small pieces. For Silicon and barium titanate glass particles, a finite number of cracks were observed in one of the particles causing it to fracture. For yttrium stabilized zirconia particles, a single meridonial crack developed in one of the particles, breaking it into two parts.« less

Balancing Particle and Mesh Computation in a Particle-In-Cell Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Worley, Patrick H; D'Azevedo, Eduardo; Hager, Robert

2016-01-01

The XGC1 plasma microturbulence particle-in-cell simulation code has both particle-based and mesh-based computational kernels that dominate performance. Both of these are subject to load imbalances that can degrade performance and that evolve during a simulation. Each separately can be addressed adequately, but optimizing just for one can introduce significant load imbalances in the other, degrading overall performance. A technique has been developed based on Golden Section Search that minimizes wallclock time given prior information on wallclock time, and on current particle distribution and mesh cost per cell, and also adapts to evolution in load imbalance in both particle and meshmore » work. In problems of interest this doubled the performance on full system runs on the XK7 at the Oak Ridge Leadership Computing Facility compared to load balancing only one of the kernels.« less

Integrated Method for Purification and Single-Particle Characterization of Lentiviral Vector Systems by Size Exclusion Chromatography and Tunable Resistive Pulse Sensing.

PubMed

Heider, Susanne; Muzard, Julien; Zaruba, Marianne; Metzner, Christoph

2017-07-01

Elements derived from lentiviral particles such as viral vectors or virus-like particles are commonly used for biotechnological and biomedical applications, for example in mammalian protein expression, gene delivery or therapy, and vaccine development. Preparations of high purity are necessary in most cases, especially for clinical applications. For purification, a wide range of methods are available, from density gradient centrifugation to affinity chromatography. In this study we have employed size exclusion columns specifically designed for the easy purification of extracellular vesicles including exosomes. In addition to viral marker protein and total protein analysis, a well-established single-particle characterization technology, termed tunable resistive pulse sensing, was employed to analyze fractions of highest particle load and purity and characterize the preparations by size and surface charge/electrophoretic mobility. With this study, we propose an integrated platform combining size exclusion chromatography and tunable resistive pulse sensing for monitoring production and purification of viral particles.

Particle size variations between bed load and bed material in natural gravel bed channels

Treesearch

Thomas E. Lisle

1995-01-01

Abstract - Particle sizes of bed load and bed material that represent materials transported and stored over a period of years are used to investigate selective transport in 13 previously sampled, natural gravel bed channels. The ratio (D*) of median particle size of bed material to the transport- and frequency-weighted mean of median bed load size decreases to unity...

In Situ Sampling of Relative Dust Devil Particle Loads and Their Vertical Grain Size Distributions.

PubMed

Raack, Jan; Reiss, Dennis; Balme, Matthew R; Taj-Eddine, Kamal; Ori, Gian Gabriele

2017-04-19

During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (∼46.5% and ∼61% of all particles; ∼76.5 wt % and ∼89 wt % of the relative particle load). Furthermore, ∼69% and ∼82% of all lifted sand grains occurred in the first meter of the dust devils, indicating the occurrence of "sand skirts." Both sampled dust devils were relatively small (∼15 m and ∼4-5 m in diameter) compared to dust devils in surrounding regions; nevertheless, measurements show that ∼58.5% to 73.5% of all lifted particles were small enough to go into suspension (<31 μm, depending on the used grain size classification). This relatively high amount represents only ∼0.05 to 0.15 wt % of the lifted particle load. Larger dust devils probably entrain larger amounts of fine-grained material into the atmosphere, which can have an influence on the climate. Furthermore, our results indicate that the composition of the surface, on which the dust devils evolved, also had an influence on the particle load composition of the dust devil vortices. The internal particle load structure of both sampled dust devils was comparable related to their vertical grain size distribution and relative particle load, although both dust devils differed in their dimensions and intensities. A general trend of decreasing grain sizes with height was also detected. Key Words: Mars-Dust devils-Planetary science-Desert soils-Atmosphere-Grain sizes. Astrobiology 17, xxx-xxx.

Fractional iron solubility of aerosol particles enhanced by biomass burning and ship emission in Shanghai, East China.

PubMed

Fu, H B; Shang, G F; Lin, J; Hu, Y J; Hu, Q Q; Guo, L; Zhang, Y C; Chen, J M

2014-05-15

In terms of understanding Fe mobilization from aerosol particles in East China, the PM2.5 particles were collected in spring at Shanghai. Combined with the backtrajectory analysis, the PM2.5/PM10 and Ca/Al ratios, a serious dust-storm episode (DSE) during the sampling was identified. The single-particle analysis showed that the major iron-bearing class is the aluminosilicate dust during DSE, while the Fe-bearing aerosols are dominated by coal fly ash, followed by a minority of iron oxides during the non-dust storm days (NDS). Chemical analyses of samples showed that the fractional Fe solubility (%FeS) is much higher during NDS than that during DSE, and a strong inverse relationship of R(2)=0.967 between %FeS and total atmospheric iron loading were found, suggested that total Fe (FeT) is not controlling soluble Fe (FeS) during the sampling. Furthermore, no relationship between FeS and any of acidic species was established, suggesting that acidic process on aerosol surfaces are not involved in the trend of iron solubility. It was thus proposed that the source-dependent composition of aerosol particles is a primary determinant for %FeS. Specially, the Al/Fe ratio is poorly correlated (R(2)=0.113) with %FeS, while the apparent relationship between %FeS and the calculated KBB(+)/Fe ratio (R(2)=0.888) and the V/Fe ratio (R(2)=0.736) were observed, reflecting that %FeS could be controlled by both biomass burning and oil ash from ship emission, rather than mineral particles and coal fly ash, although the latter two are the main contributors to the atmospheric Fe loading during the sampling. Such information can be useful improving our understanding on iron solubility on East China, which may further correlate with iron bioavailability to the ocean, as well as human health effects associated with exposure to fine Fe-rich particles in densely populated metropolis in China. Copyright © 2014 Elsevier B.V. All rights reserved.

Determining plasma parameters in cold, multi-species plasmas using Maxwell and Kappa distribution functions.

NASA Astrophysics Data System (ADS)

Jahn, J. M.; Denton, R. E.; Nose, M.; Bonnell, J. W.; Kurth, W. S.; Livadiotis, G.; Larsen, B.; Goldstein, J.

2016-12-01

Determining the total plasma density from ion data is essentially an impossible task for particle instruments. The lowest instrument energy threshold never includes the coldest particles (i.e., Emin> 0 eV), and any positive spacecraft charging—which is normal for a sunlit spacecraft—exacerbates the problem by shifting the detectable minimum energy to higher values. For ion data, traditionally field line resonance measurements of ULF waves in the magnetosphere have been used to determine the mass loading of magnetic field lines in this case. This approach delivers a reduced ion mass M that represents the mass ratio of all ions on a magnetic field line. For multi-species plasmas like the plasmasphere this bounds the problem, but it does not provide a unique solution. To at least estimate partial densities using particle instruments, one traditionally performs fits to the measured particle distribution functions under the assumption that the underlying particle distributions are Maxwellian. Uncertainties performing a fit aside, there is usually no possibility to detect a possible bi-Maxwellian distribution where one of the Maxwellians is very cold. The tail of such a distribution may fall completely below the low energy threshold of the measurement. In this paper we present a different approach to determining the fractional temperatures Ti and densities ni in a multi-species plasma. First, we describe and demonstrate an approach to determine Ti and ni that does not require fitting but relies more on the mathematical properties of the distribution functions. We apply our approach to Van Allen Probes measurements of the plasmaspheric H+, He+, and O+ distribution functions under the assumption that the particle distributions are Maxwellian. We compare our results to mass loading results from the Van Allen Probes field line resonance analyses (for composition) and to the total (electron) plasma density derived from the EFW and EMFISIS experiments. Then we expand our approach to allow for kappa distributions instead. While this introduces an additional degree of freedom and therefore requires fitting, our approach is still better constrained than the traditional Maxwell fitting and may hold the key to a better understanding of the true nature of plasmaspheric particle distributions.

Analysis of sediment production from two small semiarid basins in Wyoming

USGS Publications Warehouse

Rankl, J.G.

1987-01-01

Data were collected at two small, semiarid basins in Wyoming to determine the relation between rainfall, runoff, and sediment production. The basins were Dugout Creek tributary and Saint Marys Ditch tributary. Sufficient rainfall and runoff data were collected at Dugout Creek tributary to determine the source of sediment and the dominant sediment production processes. Because runoff from only one storm occurred in Saint Marys Ditch tributary, emphasis of the study was placed on the analysis of data collected at Dugout Creek tributary. At Dugout Creek tributary, detailed measurements were made to establish the source of sediment. To determine the quantity of material removed from headcuts during the study, two headcuts were surveyed. Aerial photographs were used to define movement of all headcuts. The total quantity of sediment removed from all headcuts between September 26, 1982, and September 26, 1983, was estimated to be 1,220 tons, or 15%-25% of the estimated total sediment load passing the streamflow-gaging station. A soil plot was used to sample upland erosion. A rainfall and runoff modeling system was used to evaluate the interaction between the physical processes which control sediment production. The greatest change in computed sediment load was caused by changing the parameter values for equations used to compute the detachment of sediment particles by rainfall and overland flow resulted in very small changes in computed sediment load. The upland areas were the primary source of sediment. A relationship was developed between the peak of storm runoff and the total sediment load for that storm runoff. The sediment concentration used to compute the total sediment load for the storm runoff was determined from sediment samples collected by two automatic pumping samplers. The coefficient of variation of the relationship is 34% with a 0.99 correlation coefficient. (Author 's abstract)

Enhanced reactivity of nZVI embedded into supermacroporous cryogels for highly efficient Cr(VI) and total Cr removal from aqueous solution.

PubMed

Jia, Zhenzhen; Shu, Yuehong; Huang, Renlong; Liu, Junguang; Liu, Lingling

2018-05-01

Novel supermacroporous PSA-nZVI composites with nanoscale zero-valent iron particles (nZVI) embedded into poly (sodium acrylate) (PSA) cryogels were synthesized through ion exchange followed by in-situ reduction. The magnetic composites were evaluated for material characterizations and their efficiency for Cr(VI) and total Cr removal from aqueous medium in batch experiments. PSA-nZVI composites with high nZVI loading capacity up to 128.70 mg Fe/g PSA were obtained, and the interconnected macroporous structure of PSA cryogel remained unaltered with nZVI uniformly distributed on PSA cryogel as determined by TGA, SEM, TEM, XRD and XPS analyses. PSA-nZVI composites showed faster reaction rate than free nZVI both for Cr(VI) and total Cr removal, suggesting no mass transfer resistance and the enhanced reactivity of nZVI in PSA carrier. PSA-nZVI composites exhibited much more remarkable performance for Cr(VI) and total Cr removal than free nZVI particles in high removal capacity and broad pH application range (pH 4-10). The reaction mechanisms were also elucidated with XPS analyses before and after Cr(VI) reduction reactions. These results demonstrate that PSA cryogel acts as an excellent carrier and shows multiple functions in nZVI particle dispersion, pH buffering and oxidation resistance in addition to immobilizing nZVI particles from release. Copyright © 2018 Elsevier Ltd. All rights reserved.

Composition and temporal stability of turf sediments on inner-shelf coral reefs.

PubMed

Gordon, Sophie E; Goatley, Christopher H R; Bellwood, David R

2016-10-15

Elevated sediment loads within the epilithic algal matrix (EAM) of coral reefs can increase coral mortality and inhibit herbivory. Yet the composition, distribution and temporal variability of EAM sediment loads are poorly known, especially on inshore reefs. This study quantified EAM sediment loads (including organic particulates) and algal length across the reef profile of two bays at Orpheus Island (inner-shelf Great Barrier Reef) over a six month period. We examined the total sediment mass, organic load, carbonate and silicate content, and the particle sizes of EAM sediments. Throughout the study period, all EAM sediment variables exhibited marked variation among reef zones. However, EAM sediment loads and algal length were consistent between bays and over time, despite major seasonal variation in climate including a severe tropical cyclone. This study provides a comprehensive description of EAM sediments on inshore reefs and highlights the exceptional temporal stability of EAM sediments on coral reefs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sedimentary regimes at Potter Cove, King George Island, maritime Antarctica - from source to sink

NASA Astrophysics Data System (ADS)

Monien, Donata; Monien, Patrick; Brünjes, Robert M.; Widmer, Tatjana; Schnetger, Bernhard; Brumsack, Hans-Jürgen

2013-04-01

Increased particle run-off due to recently retreated ice masses along the Antarctic margins may play an important role in fertilizing the high-nutrient-low-chlorophyll regions of the Southern Ocean. At Potter Cove, King George Island, maritime Antarctica, small melt water streams at the south-eastern shoreline (Potter Peninsula) discharge up to 1,500 mg L-1 (av. 110 mg L-1) of suspended particle matter (SPM) per day into the coastal water body during the summer seasons. Apart from potential light limitation of plankton growth by the suspension load, the particle run-off affects benthic feeders, possibly changes the depositional regime and the preservation of chemical proxies in the outlet zones, and exports trace elements offshore. In Potter Cove's water column, the average particle size is low, and extreme turbidity events are restricted to the upper five to seven meters. High particle loads are often associated with low salinities, most probably induced by increased onshore precipitation. Sediment traps installed in the inner and outer cove at 5 and 20 m water depth suggest mass accumulation rates of 0.83 and 0.58 g cm-2 yr-1, and 0.13 and 0.11 g cm-2 yr-1 (considering 183 days of sedimentation), respectively. 210Pb measurements of short sediment cores reveal recent sediment accumulation rates of approximately 0.1 to 0.6 g cm-2 yr-1. The SPM sampled in the melt water streams and plumes is chemically different to surface sediments deposited in Potter Cove. Chemical characteristics suggest a significant impact of particle sorting: SPM and outer cove sediments are more clayey, whereas inner cove sediments contain more heavy minerals. Generally, sediment deposits in Potter Cove exhibit coarser grain sizes and are mainly derived from Barton Peninsula (northern shoreline), whereas the SPM consists of more fine-grained material originating from Potter Peninsula eluviations. Sequential leaching of the SPM by ascorbic acid showed that approximately 0.5 to 2% of the total iron (5.9 wt.% Fe) is easily dissolvable, which in turn can be translated into an additional load of approximately 5 to 21 mmol L-1 dissolved Fe2+. In consequence, the results of our three-summer study highlight that the major part of the particle load from the melt water streams are exported to the Southern Ocean rather than being deposited near shore in Potter Cove. These exported particles are rich in easily leachable Fe acting as a natural fertilization to the Fe-limited Southern Ocean.

The load-bearing ability of a particle raft under the transverse compression of a slender rod.

PubMed

Zuo, Pingcheng; Liu, Jianlin; Li, Shanpeng

2017-03-22

Liquid marbles and particle rafts are liquid interfaces covered with tiny particles, which are accompanied with many exotic behaviors. This study seeks to extend our understanding on the load-bearing ability of a particle raft under the transverse compression of a slender rod. At first, the interface morphologies of the particle raft and water are captured and compared with each other. Then the load-distance curves of the particle raft and water surface are measured using a self-developed device. For the particle raft, the hydrophobicity of the rod almost does not affect the interface morphology and the supporting load. To address the mechanism of this phenomenon, we perform the experiment and find that the surface tension of the particle raft is almost the same as that of water, but the equivalent contact angle of the rod attached to the particles is greatly enhanced. Finally, the model of an axisymmetrical rod pressing liquid is built, and the numerical result is in excellent agreement with the experimental data. These analyses may be beneficial to the measurement of mechanical behaviors for soft interfaces, separation of oil and water, flotation in minerals, and design of miniature boats.

Periprosthetic wear particle migration and distribution modelling and the implication for osteolysis in cementless total hip replacement.

PubMed

Alidousti, Hamidreza; Taylor, Mark; Bressloff, Neil W

2014-04-01

In total hip replacement (THR), wear particles play a significant role in osteolysis and have been observed in locations as remote as the tip of femoral stem. However, there is no clear understanding of the factors and mechanisms causing, or contributing to particle migration to the periprosthetic tissue. Interfacial gaps provide a route for particle laden joint fluid to transport wear particles to the periprosthetic tissue and cause osteolysis. It is likely that capsular pressure, gap dimensions and micromotion of the gap during cyclic loading of an implant, play defining roles to facilitate particle migration. In order to obtain a better understanding of the above mechanisms and factors, transient two-dimensional computational fluid dynamic simulations have been performed for the flow in the lateral side of a cementless stem-femur system including the joint capsule, a gap in communication with the capsule and the surrounding bone. A discrete phase model to describe particle motion has been employed. Key findings from these simulations include: (1) Particles were shown to enter the periprosthetic tissue along the entire length of the gap but with higher concentrations at both proximal and distal ends of the gap and a maximum rate of particle accumulation in the distal regions. (2) High capsular pressure, rather than gap micromotion, has been shown to be the main driving force for particle migration to periprosthetic tissue. (3) Implant micromotion was shown to pump out rather than draw in particles to the interfacial gaps. (4) Particle concentrations are consistent with known distributions of (i) focal osteolysis at the distal end of the gap and (ii) linear osteolysis along the entire gap length. Copyright © 2014 Elsevier Ltd. All rights reserved.

The transition from intermittent to continuous bed-load transport arises from merger of "bursty" transport events

NASA Astrophysics Data System (ADS)

Lee, D. B.; Jerolmack, D. J.

2017-12-01

Bed-load transport is notoriously unpredictable, in part due to stochastic fluctuations in grain entrainment and deposition. A general statistical mechanical framework has been proposed by Furbish and colleagues to formally derive average bed-load flux from grain-scale motion, and its application requires an intimate understanding of the probabilistic motion of individual grains. Recent work by Ancey et al. suggests that, near threshold, particles are entrained collectively. If so, understanding the scales of correlation is a necessary step to complete the probabilistic framework describing bed-load flux. We perform a series of experiments in a steep-sloped channel that directly quantifies fluctuations in grain motion as a function of the feed rate of particles (marbles). As the feed rate is increased, the necessary averaging time is decreased (i.e. transport grows less variable in time). Collective grain motion is defined as spatially clustered movement of several grains at once. We find that entrainment of particles is generally collective, but that these entrained particles deposit independently of each other. The size distribution of collective motion events follows an exponential decay that is consistent across sediment feed rates. To first order, changing feed rate does not change the kinematics of mobile grains, just the frequency of motion. For transport within a given region of the bed, we show that the total displacement of all entrained grains is proportional to the kinetic energy deposited into the bed by impacting grains. Individual grain-bed impacts are the likely cause of both collective and individual grain entrainment. The picture that emerges is similar to generic avalanching dynamics in sandpiles: "avalanches" (collective entrainment events) of a characteristic size relax with a characteristic timescale regardless of feed rate, but the frequency of avalanches increases in proportion to the feed rate. At high enough feed rates the avalanches merge, leading to progressively smoother and continuous transport. As most bed-load transport occurs in the intermittent regime, the length scale of collective entrainment should be considered a fundamental addition to a probabilistic framework that hopes to infer flux from grain motion.

Physical properties, chemical composition, and cloud forming potential of particulate emissions from a marine diesel engine at various load conditions.

PubMed

Petzold, A; Weingartner, E; Hasselbach, J; Lauer, P; Kurok, C; Fleischer, F

2010-05-15

Particulate matter (PM) emissions from one serial 4-stroke medium-speed marine diesel engine were measured for load conditions from 10% to 110% in test rig studies using heavy fuel oil (HFO). Testing the engine across its entire load range permitted the scaling of exhaust PM properties with load. Emission factors for particle number, particle mass, and chemical compounds were determined. The potential of particles to form cloud droplets (cloud condensation nuclei, CCN) was calculated from chemical composition and particle size. Number emission factors are (3.43 +/- 1.26) x 10(16) (kg fuel)(-1) at 85-110% load and (1.06 +/- 0.10) x 10(16) (kg fuel)(-1) at 10% load. CCN emission factors of 1-6 x 10(14) (kg fuel)(-1) are at the lower bound of data reported in the literature. From combined thermal and optical methods, black carbon (BC) emission factors of 40-60 mg/(kg fuel) were determined for 85-100% load and 370 mg/(kg fuel) for 10% load. The engine load dependence of the conversion efficiency for fuel sulfur into sulfate of (1.08 +/- 0.15)% at engine idle to (3.85 +/- 0.41)% at cruise may serve as input to global emission calculations for various load conditions.

Summary of sediment data from the Yampa river and upper Green river basins, Colorado and Utah, 1993-2002

USGS Publications Warehouse

Elliott, John G.; Anders, Steven P.

2004-01-01

The water resources of the Upper Colorado River Basin have been extensively developed for water supply, irrigation, and power generation through water storage in upstream reservoirs during spring runoff and subsequent releases during the remainder of the year. The net effect of water-resource development has been to substantially modify the predevelopment annual hydrograph as well as the timing and amount of sediment delivery from the upper Green River and the Yampa River Basins tributaries to the main-stem reaches where endangered native fish populations have been observed. The U.S. Geological Survey, in cooperation with the Colorado Division of Wildlife and the U.S. Fish and Wildlife Service, began a study to identify sediment source reaches in the Green River main stem and the lower Yampa and Little Snake Rivers and to identify sediment-transport relations that would be useful in assessing the potential effects of hydrograph modification by reservoir operation on sedimentation at identified razorback spawning bars in the Green River. The need for additional data collection is evaluated at each sampling site. Sediment loads were calculated at five key areas within the watershed by using instantaneous measurements of streamflow, suspended-sediment concentration, and bedload. Sediment loads were computed at each site for two modes of transport (suspended load and bedload), as well as for the total-sediment load (suspended load plus bedload) where both modes were sampled. Sediment loads also were calculated for sediment particle-size range (silt-and-clay, and sand-and-gravel sizes) if laboratory size analysis had been performed on the sample, and by hydrograph season. Sediment-transport curves were developed for each type of sediment load by a least-squares regression of logarithmic-transformed data. Transport equations for suspended load and total load had coefficients of determination of at least 0.72 at all of the sampling sites except Little Snake River near Lily, Colorado. Bedload transport equations at the five sites had coefficients of determination that ranged from 0.40 (Yampa River at Deerlodge Park, Colorado) to 0.80 (Yampa River above Little Snake River near Maybell, Colorado). Transport equations for silt and clay-size material had coefficients of determination that ranged from 0.46 to 0.82. Where particle-size data were available (Yampa River at Deerlodge Park, Colorado, and Green River near Jensen, Utah), transport equations for the smaller particle sizes (fine sand) tended to have higher coefficients of determination than the equations for coarser sizes (medium and coarse sand, and very coarse sand and gravel). Because the data had to be subdivided into at least two subsets (rising-limb, falling-limb and, occasionally, base-flow periods), the seasonal transport equations generally were based on relatively few samples. All transport equations probably could be improved by additional data collected at strategically timed periods.

Porous titanium particles for acetabular reconstruction in total hip replacement show extensive bony armoring after 15 weeks

PubMed Central

Walschot, Lucas H B; Aquarius, René; Verdonschot, Nico; Buma, Pieter

2014-01-01

Background and purpose — The bone impaction grafting technique restores bone defects in total hip replacement. Porous titanium particles (TiPs) are deformable, like bone particles, and offer better primary stability. We addressed the following questions in this animal study: are impacted TiPs osteoconductive under loaded conditions; do released micro-particles accelerate wear; and are systemic titanium blood levels elevated after implantation of TiPs? Animals and methods — An AAOS type-III defect was created in the right acetabulum of 10 goats weighing 63 (SD 6) kg, and reconstructed with calcium phosphate-coated TiPs and a cemented polyethylene cup. A stem with a cobalt chrome head was cemented in the femur. The goats were killed after 15 weeks. Blood samples were taken pre- and postoperatively. Results — The TiP-graft layer measured 5.6 (SD 0.8) mm with a mean bone ingrowth distance of 2.8 (SD 0.8) mm. Cement penetrated 0.9 (0.3–1.9) mm into the TiPs. 1 reconstruction showed minimal cement penetration (0.3 mm) and failed at the cement-TiP interface. There were no signs of accelerated wear, metallic particle debris, or osteolysis. Median systemic titanium concentrations increased on a log-linear scale from 0.5 (0.3–1.1) parts per billion (ppb) to 0.9 (0.5–2.8) ppb (p = 0.01). Interpretation — Adequate cement pressurization is advocated for impaction grafting with TiPs. After implantation, calcium phosphate-coated TiPs were osteoconductive under loaded conditions and caused an increase in systemic titanium concentrations. However, absolute levels remained low. There were no signs of accelerated wear. A clinical pilot study should be performed to prove that application in humans is safe in the long term. PMID:25238431

ASME AG-1 Section FC Qualified HEPA Filters; a Particle Loading Comparison - 13435

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stillo, Andrew; Ricketts, Craig I.

High Efficiency Particulate Air (HEPA) Filters used to protect personnel, the public and the environment from airborne radioactive materials are designed, manufactured and qualified in accordance with ASME AG-1 Code section FC (HEPA Filters) [1]. The qualification process requires that filters manufactured in accordance with this ASME AG-1 code section must meet several performance requirements. These requirements include performance specifications for resistance to airflow, aerosol penetration, resistance to rough handling, resistance to pressure (includes high humidity and water droplet exposure), resistance to heated air, spot flame resistance and a visual/dimensional inspection. None of these requirements evaluate the particle loading capacitymore » of a HEPA filter design. Concerns, over the particle loading capacity, of the different designs included within the ASME AG-1 section FC code[1], have been voiced in the recent past. Additionally, the ability of a filter to maintain its integrity, if subjected to severe operating conditions such as elevated relative humidity, fog conditions or elevated temperature, after loading in use over long service intervals is also a major concern. Although currently qualified HEPA filter media are likely to have similar loading characteristics when evaluated independently, filter pleat geometry can have a significant impact on the in-situ particle loading capacity of filter packs. Aerosol particle characteristics, such as size and composition, may also have a significant impact on filter loading capacity. Test results comparing filter loading capacities for three different aerosol particles and three different filter pack configurations are reviewed. The information presented represents an empirical performance comparison among the filter designs tested. The results may serve as a basis for further discussion toward the possible development of a particle loading test to be included in the qualification requirements of ASME AG-1 Code sections FC and FK[1]. (authors)« less

Physicochemical and toxicological characteristics of particulate matter emitted from a non-road diesel engine: comparative evaluation of biodiesel-diesel and butanol-diesel blends.

PubMed

Zhang, Zhi-Hui; Balasubramanian, Rajasekhar

2014-01-15

Combustion experiments were conducted to evaluate the effects of using blends of ultralow sulfur diesel (ULSD) with biodiesel or n-butanol on physicochemical and toxicological characteristics of particulate emissions from a non-road diesel engine. The results indicated that compared to ULSD, both the blended fuels could effectively reduce the particulate mass and elemental carbon emissions, with butanol being more effective than biodiesel. The proportion of organic carbon and volatile organic compounds in particles increased for both blended fuels. However, biodiesel blended fuels showed lower total particle-phase polycyclic aromatic hydrocarbons (PAHs) emissions. The total number emissions of particles ≤560nm in diameter decreased gradually for the butanol blended fuels, but increased significantly for the biodiesel blended fuels. Both the blended fuels indicated lower soot ignition temperature and activation energy. All the particle extracts showed a decline in cell viability with the increased dose. However, the change in cell viability among test fuels is not statistically significant different with the exception of DB-4 (biodiesel-diesel blend containing 4% oxygen) used at 75% engine load. Copyright © 2013 Elsevier B.V. All rights reserved.

The significance of relative density for particle damage in loaded and sheared gravels

NASA Astrophysics Data System (ADS)

Fityus, Stephen; Imre, Emőke

2017-06-01

For granular assemblages of strong particles, an increase in the relative density usually leads to a significant increase in shear strength, which is evident as a peak strength, accompanied by significant dilation as the peak strength is attained. This paper describes an experimental study of shearing in assemblages of weak particles, where particle breakage offsets dilation for all but the lowest of confining stresses. In such materials, prone to particle breakage, the shear strengths of loose and dense assemblages rapidly converge to similar values as confining stress increases, and any benefit of greater relative density is lost. This is attributed to the densification effect associated with the loading under a high stress prior to shearing, which is characterised by widespread particle breakage and the formation of smaller particles to occupy space between coarser ones. Interestingly, under both low and high stresses, there was a tendency for greater particle breakage in the loose samples, as a result of both shearing and compression. This result suggests that, despite the denser assemblage having its particles more rigidly constrained and less able to rearrange to avoid direct loading, the influence of greater load-spreading capacity afforded by an increased number of particle contacts in a denser sample, is more dominant in controlling breakage.

Removal of total coliform and E. coli using zeliac as filter media

NASA Astrophysics Data System (ADS)

Ibrahim, Nurazim; Aziz, Hamidi Abdul; Yusoff, Mohd Suffian

2017-10-01

High loading of wastewater and surface run off into river contributed to large amount of microorganisms entering drinking water sources. The aim of this study was to investigate the capability of composite adsorbent namely Zeliac to remove total coliform and E. coli from river water using fixed bed column experiment. Two ranges of Zeliac particle sizes (1.18- 2 mm and 0.425- 0.6 mm) were applied to observe the effect of particle size on the removal of the selected pollutants. Kerian River water with a total coliform and E. coli concentration of 14, 082 ± 4, 209 and 208 ± 166 MPN/100 mL respectively was continuously supplied to the column at constant flow rate of 20 (Column A) and 21 ml/min (Column B) for 991 hours. The presence of total coliform and E. coli in the treated water were detected using Colilert test kit from IDEXX Corporation. The performance of Zeliac as filter media was analysed by a breakthrough curve plotted from normalized concentration (C/Co) against time. It was discovered that a difference in particle size does not give a significant impact to the removal of total coliform and E. coli in this system. According to the plotted breakthrough curves, Zeliac as filter media was capable to immobilize total coliform and E. coli for up to 31 hours of contact time. This finding shows that Zeliac has the potential to retain pathogenic microorganism such as E. coli in a continuous fluid flow.

Investigations of Sediment Transportation, Middle Loup River at Dunning, Nebraska: With Application of Data from Turbulence Flume

USGS Publications Warehouse

Hubbell, David Wellington; Matejka, Donald Quintin

1959-01-01

An investigation of fluvial sediments of the Middle Loup River at Dunning, Nebr., was begun in 1946 and expanded in 1949 to provide information on sediment transportation. Construction of an artificial turbulence flume at which the total sediment discharge of the Middle Loup River at Dunning, Nebr., could be measured with suspended-sediment sampling equipment was completed in 1949. Since that time. measurements have been made at the turbulence flume and at several selected sections in a reach upstream and downstream from the flume. The Middle Loup River upstream from Dunning traverses the sandhills region of north-central Nebraska and has a drainage area of approximately 1,760 square miles. The sandhills are underlain by the Ogallala formation of Tertiary age and are mantled by loess and dune sand. The topography is characterized by northwest-trending sand dunes, which are stabilized by grass cover. The valley floor upstream from Dunning is generally about half a mile wide, is about 80 feet lower than the uplands, and is composed of sand that was mostly stream deposited. The channel is defined by low banks. Bank erosion is prevalent and is the source of most of the sediment load. The flow originates mostly from ground-water accretion and varies between about 200 and 600 cfs (cubic feet per second). Measured suspended-sediment loads vary from about 200 to 2,000 tons per day, of which about 20 percent is finer than 0.062 millimeter and 100 percent is finer than 0.50 millimeter. Total sediment discharges vary from about 500 to 3,500 tons per day, of which about 10 percent is finer than 0.062 millimeter, about 90 percent is finer than 0.50 millimeter, and about 98 percent is finer than 2.0 millimeters. The measured suspended-sediment discharge in the reach near Dunning averages about one-half of the total sediment discharge as measured at the turbulence flume. This report contains information collected during the period October 1, 1948, to September 30, 1952. The information includes sediment discharges; particle-size analyses of total load, of measured suspended sediment, and of bed material; water discharges and other hydraulic data for the turbulence flume and the selected sections. Sediment discharges have been computed with several different formulas, and insofar as possible, each computed load has been compared with data from the turbulence flume. Sediment discharges computed with the Einstein procedure did not agree well, in general, with comparable measured loads. However, a satisfactory representative cross section for the reach could not be determined with the cross sections that were selected for this investigation. If the computed cross section was narrower and deeper than a representative cross section for the reach, computed loads were high; and if the computed cross section was wider and shallower than a representative cross section for the reach, computed loads were low. Total sediment discharges computed with the modified Einstein procedure compared very well with the loads of individual size ranges and the measured total loads at the turbulence flume. Sediment discharges computed with the Straub equation averaged about twice the measured total sediment discharge at the turbulence flume. Bed-load discharges computed with the Kalinske equation were of about the right magnitude; however, high computed loads were associated with low total loads, low unmeasured loads, and low concentrations of measured suspended sediment coarser than 0.125 millimeter. Bed-load discharges computed with the Schoklitsch equation seemed somewhat high; about one-third of the computed loads were slightly higher than comparable unmeasured loads. Although, in general, high computed discharges with the Schoklitsch equation were associated with high measured total loads, high unmeasured loads, and high concentrations of measured suspended sediment coarser than 0.125 millimeter, the trend was not consistent. Bed-load discharges computed

Atmospheric particles retrieval using satellite remote sensing: Applications for sandstorms and volcanic clouds

NASA Astrophysics Data System (ADS)

Gu, Yingxin

This thesis is concerned with atmospheric particles produced by sandstorms and volcanic eruptions. Three studies were conducted in order to examine particle retrieval methodology, and apply these towards an improved understanding of large-scale sandstorms. A thermal infrared remote sensing retrieval method developed by Wen and Rose [1994], which retrieves particle sizes, optical depth, and total masses of silicate particles in the volcanic cloud, was applied to an April 07, 2001 sandstorm over northern China, using MODIS. Results indicate that the area of the dust cloud observed was 1.34 million km2, the mean particle radius of the dust was 1.44 mum, and the mean optical depth at 11 mum was 0.79. The mean burden of dust was approximately 4.8 tons/km2 and the main portion of the dust storm on April 07, 2001 contained 6.5 million tons of dust. The results are supported by both independent remote sensing data (TOMS) and in-situ data for a similar event in 1998, therefore suggesting that the technique is appropriate for quantitative analysis of silicate dust clouds. This is the first quantitative evaluation of annual and seasonal dust loading in 2003 produced by Saharan dust storms by satellite remote sensing analysis. The retrieved mean particle effective radii of 2003 dust events are between 1.7--2.6 mum which is small enough to be inhaled and is hazardous to human health. The retrieved yearly dust mass load is 658--690 Tg, which is ˜45% of the annual global mineral dust production. Winter is the heaviest dust loading season in the year 2003, which is more than 5 times larger than that in the summer season in 2003.The mean optical depths at 11 mum in the winter season (around 0.7) are higher than those in the summer season (around 0.5). The results could help both meteorologists and environmental scientists to evaluate and predict the hazard degree caused by Saharan dust storms. (Abstract shortened by UMI.)

Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries.

PubMed

David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

2016-03-30

Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm(-2)) delivers a charge capacity of ∼588 mAh g(-1)electrode (∼393 mAh cm(-3)electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries.

Application and advantages of novel clay ceramic particles (CCPs) in an up-flow anaerobic bio-filter (UAF) for wastewater treatment.

PubMed

Han, Wei; Yue, Qinyan; Wu, Suqing; Zhao, Yaqin; Gao, Baoyu; Li, Qian; Wang, Yan

2013-06-01

Utilization of clay ceramic particles (CCPs) as the novel filter media employed in an up-flow anaerobic bio-filter (UAF) was investigated. After a series of tests and operations, CCPs have presented higher total porosity and roughness, meanwhile lower bulk and grain density. When CCPs were utilized as fillers, the reactor had a shorter start up period of 45 days comparing with conventional reactors, and removal rate of chemical oxygen demand (COD) still reached about 76% at a relatively lower temperature during the stable state. In addition, degradation of COD and ammonia nitrogen (NH4-N) at different media height along the reactor was evaluated, and the dates showed that the main reduction process happened within the first 30 cm media height from the bottom flange. Five phases were observed according to different organic loadings during the experiment period, and the results indicated that COD removal increased linearly when the organic loading was increased. Copyright © 2013 Elsevier Ltd. All rights reserved.

Fracture mechanisms of glass particles under dynamic compression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Niranjan D.; Guo, Zherui; Hudspeth, Matthew C.

2017-08-01

In this study, dynamic fracture mechanisms of single and contacting spherical glass particles were observed using high speed synchrotron X-ray phase contrast imaging. A modified Kolsky bar setup was used to apply controlled dynamic compressive loading on the soda-lime glass particles. Four different configurations of particle arrangements with one, two, three, and five particles were studied. In single particle experiments, cracking initiated near the contact area between the particle and the platen, subsequently fragmenting the particle in many small sub-particles. In multi-particle experiments, a crack was observed to initiate from the point just outside the contact area between two particles.more » The initiated crack propagated at an angle to the horizontal loading direction, resulting in separation of a fragment. However, this fragment separation did not affect the ability of the particle to withstand further contact loading. On further compression, large number of cracks initiated in the particle with the highest number of particle-particle contacts near one of the particle-particle contacts. The initiated cracks roughly followed the lines joining the contact points. Subsequently, the initiated cracks along with the newly developed sub-cracks bifurcated rapidly as they propagated through the particle and fractured the particle explosively into many small fragments, leaving the other particles nearly intact.« less

Alpha spectrometric characterization of process-related particle size distributions from active particle sampling at the Los Alamos National Laboratory uranium foundry

NASA Astrophysics Data System (ADS)

Plionis, A. A.; Peterson, D. S.; Tandon, L.; LaMont, S. P.

2010-03-01

Uranium particles within the respirable size range pose a significant hazard to the health and safety of workers. Significant differences in the deposition and incorporation patterns of aerosols within the respirable range can be identified and integrated into sophisticated health physics models. Data characterizing the uranium particle size distribution resulting from specific foundry-related processes are needed. Using personal air sampling cascade impactors, particles collected from several foundry processes were sorted by activity median aerodynamic diameter onto various Marple substrates. After an initial gravimetric assessment of each impactor stage, the substrates were analyzed by alpha spectrometry to determine the uranium content of each stage. Alpha spectrometry provides rapid non-distructive isotopic data that can distinguish process uranium from natural sources and the degree of uranium contribution to the total accumulated particle load. In addition, the particle size bins utilized by the impactors provide adequate resolution to determine if a process particle size distribution is: lognormal, bimodal, or trimodal. Data on process uranium particle size values and distributions facilitate the development of more sophisticated and accurate models for internal dosimetry, resulting in an improved understanding of foundry worker health and safety.

Most microbeads in a preliminary survey of personal care products are smaller than the typical 330µm trawl mesh size used in surface water surveys

NASA Astrophysics Data System (ADS)

Conkle, J. L.; Baez-Del Valle, C.; Turner, J.

2016-02-01

Research on plastic debris in aquatic environments, particularly the ocean, has recently exploded due to our emerging understanding of their ubiquitous presence and organismal effects. One study estimated that hundreds of thousands of tons of plastic float at our ocean surface, while another estimated that up to 12.7 million metric tons enter the ocean in a year. These studies produced reasonable estimates of oceanic loads, but research is needed to understand the sources and properties of plastics, particularly microplastics, entering the environment. In this preliminary study, polyethylene (PE) microbeads from 6 facial scrubs, 4 body washes and 3 toothpaste products were extracted and quantified by mass and particle count for the following size classes: 50, 100, 200, 300, 400, 500 and 1000µm. Within the product classes, roughly half (face scrub, 55% and body wash, 48%) to nearly all (toothpaste, 97%) of PE microbeads on a mass basis were smaller than 300µm in diameter. When examining the size distribution by particle count, the results were even more astounding. Nearly all PE microbeads were smaller than 300µm for face scrub (95%), body wash (97%) and toothpaste (100%). The 300µm particle diameter is significant, as major surveys in the published literature (Eriksen et al., 2014; Law et al, 2014) used 330µm or greater mesh size to sample plastic debris and estimate oceanic plastic loads. Therefore, these published surveys, which are some of our best estimates of plastic debris at the ocean surface, likely underestimate total environmental loads because they may exclude half of the mass and nearly all of the individual PE microbead particles that enter our waste stream and potentially surface waters after the use of personal care products.

Characterization of heavy metal desorption from road-deposited sediment under acid rain scenarios.

PubMed

Zhao, Bo; Liu, An; Wu, Guangxue; Li, Dunzhu; Guan, Yuntao

2017-01-01

Road-deposited sediments (RDS) on urban impervious surfaces are important carriers of heavy metals. Dissolved heavy metals that come from RDS influenced by acid rain, are more harmful to urban receiving water than particulate parts. RDS and its associated heavy metals were investigated at typical functional areas, including industrial, commercial and residential sites, in Guangdong, Southern China, which was an acid rain sensitive area. Total and dissolved heavy metals in five particle size fractions were analyzed using a shaking method under acid rain scenarios. Investigated heavy metals showed no difference in the proportion of dissolved fraction in the solution under different acid rain pHs above 3.0, regardless of land use. Dissolved loading of heavy metals related to organic carbon content were different in runoff from main traffic roads of three land use types. Coarse particles (>150μm) that could be efficiently removed by conventional street sweepers, accounted for 55.1%-47.1% of the total dissolved metal loading in runoff with pH3.0-5.6. The obtained findings provided a significant scientific basis to understand heavy metal release and influence of RDS grain-size distribution and land use in dissolved heavy metal pollution affected by acid rain. Copyright © 2016. Published by Elsevier B.V.

Dynamic Load Balancing Based on Constrained K-D Tree Decomposition for Parallel Particle Tracing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jiang; Guo, Hanqi; Yuan, Xiaoru

Particle tracing is a fundamental technique in flow field data visualization. In this work, we present a novel dynamic load balancing method for parallel particle tracing. Specifically, we employ a constrained k-d tree decomposition approach to dynamically redistribute tasks among processes. Each process is initially assigned a regularly partitioned block along with duplicated ghost layer under the memory limit. During particle tracing, the k-d tree decomposition is dynamically performed by constraining the cutting planes in the overlap range of duplicated data. This ensures that each process is reassigned particles as even as possible, and on the other hand the newmore » assigned particles for a process always locate in its block. Result shows good load balance and high efficiency of our method.« less

Repetitive heterocoagulation of oppositely charged particles for enhancement of magnetic nanoparticle loading into monodisperse silica particles.

PubMed

Matsumoto, Hideki; Nagao, Daisuke; Konno, Mikio

2010-03-16

Oppositely charged particles were repetitively heterocoagulated to fabricate highly monodisperse magnetic silica particles with high loading of magnetic nanoparticles. Positively charged magnetic nanoparticles prepared by surface modification with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TSA) were used to heterocoagulate with silica particles under basic conditions to give rise to negative silica surface charge and prevent the oxidation of the magnetic nanoparticles. The resultant particles of silica core homogeneously coated with the magnetic nanoparticles were further coated with thin silica layer with sodium silicate in order to enhance colloidal stability and avoid desorption of the magnetic nanoparticles from the silica cores. Five repetitions of the heterocoagulation and the silica coating could increase saturation magnetization of the magnetic silica particles to 27.7 emu/g, keeping the coefficient of variation of particle sizes (C(V)) less than 6.5%. Highly homogeneous loading of the magnetic component was confirmed by measuring Fe-to-Si atomic ratios of individual particles with energy dispersive X-ray spectroscopy.

Distribution and transport of polychlorinated biphenyls and associated particulates in the Milwaukee River System, Wisconsin, 1993-95

USGS Publications Warehouse

Steuer, Jeffrey S.; Fitzgerald, Sharon A.; Hall, David W.

1999-01-01

The distribution and transport of polychlorinated biphenyl (PCB) congeners were determined at various sites on Cedar Creek and its receiving stream, the Milwaukee River. PCB congener distributions were determined in the operationally defined dissolved phase, suspended-particle phase, and surficial bed sediments (0?2 centimeters depth). At most sites, the relative abundances of PCB congeners in the suspended particles and surficial bed sediments were similar to each other, and in some cases, to known Aroclor mixtures (1242 and 1260). Dissolved PCB congener distributions were higher in the less chlorinated congeners as predicted by their lower hydrophobicity and higher solubility. Log partition coefficients for the dissolved and the particle-associated organic carbon phases ranged from 5.0 to 5.8 and 6.5 to 7.5, respectively, for SPCB?s (congener summation). Particle-associated PCB?s exhibited two patterns: (1) a general increase in spring and summer associated with algal growth and, (2) episodic increases associated with resuspension of bed sediments during storms. Total suspended solids loads in water year 1994 ranged from 8,700 tons at Pioneer Road to 15,800 tons at Estabrook Park. PCB loads decreased from Highland Road (3.7 kilograms) to Pioneer Road (1.8 kilograms) from August 1994 to August 1995, indicating PCB deposition between those sites. PCB transport at Estabrook Park was 8 to 16 kilograms during this same time period.

Acoustic bed velocity and bed load dynamics in a large sand bed river

USGS Publications Warehouse

Gaeuman, D.; Jacobson, R.B.

2006-01-01

Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load transport. However, a better understanding of how ADCP data relate to conditions near the stream bed is necessary to make the method practical for quantitative applications. In this paper, we discuss the response of ADCP bed velocity measurements, defined as the near-bed sediment velocity detected by the instrument's bottom-tracking feature, to changing sediment-transporting conditions in the lower Missouri River. Bed velocity represents a weighted average of backscatter from moving bed load particles and spectral reflections from the immobile bed. The ratio of bed velocity to mean bed load particle velocity depends on the concentration of the particles moving in the bed load layer, the bed load layer thickness, and the backscatter strength from a unit area of moving particles relative to the echo strength from a unit area of unobstructed bed. A model based on existing bed load transport theory predicted measured bed velocities from hydraulic and grain size measurements with reasonable success. Bed velocities become more variable and increase more rapidly with shear stress when the transport stage, defined as the ratio of skin friction to the critical shear stress for particle entrainment, exceeds a threshold of about 17. This transition in bed velocity response appears to be associated with the appearance of longer, flatter bed forms at high transport stages.

Simulated rain events on an urban roadway to understand the dynamics of mercury mobilization in stormwater runoff.

PubMed

Eckley, Chris S; Branfireun, Brian

2009-08-01

This research focuses on mercury (Hg) mobilization in stormwater runoff from an urban roadway. The objectives were to determine: how the transport of surface-derived Hg changes during an event hydrograph; the influence of antecedent dry days on the runoff Hg load; the relationship between total suspended sediments (TSS) and Hg transport, and; the fate of new Hg input in rain and its relative importance to the runoff Hg load. Simulated rain events were used to control variables to elucidate transport processes and a Hg stable isotope was used to trace the fate of Hg inputs in rain. The results showed that Hg concentrations were highest at the beginning of the hydrograph and were predominantly particulate bound (HgP). On average, almost 50% of the total Hg load was transported during the first minutes of runoff, underscoring the importance of the initial runoff on load calculations. Hg accumulated on the road surface during dry periods resulting in the Hg runoff load increasing with antecedent dry days. The Hg concentrations in runoff were significantly correlated with TSS concentrations (mean r(2)=0.94+/-0.09). The results from the isotope experiments showed that the new Hg inputs quickly become associated with the surface particles and that the majority of Hg in runoff is derived from non-event surface-derived sources.

An analysis of field-aged diesel particulate filter performance: particle emissions before, during, and after regeneration.

PubMed

Barone, Teresa L; Storey, John M E; Domingo, Norberto

2010-08-01

A field-aged, passive diesel particulate filter (DPF) used in a school bus retrofit program was evaluated for emissions of particle mass and number concentration before, during, and after regeneration. For the particle mass measurements, filter samples were collected for gravimetric analysis with a partial flow sampling system, which sampled proportionally to the exhaust flow. A condensation particle counter and scanning mobility particle sizer measured total number concentration and number-size distributions, respectively. The results of the evaluation show that the number concentration emissions decreased as the DPF became loaded with soot. However, after soot removal by regeneration, the number concentration emissions were approximately 20 times greater, which suggests the importance of the soot layer in helping to trap particles. Contrary to the number concentration results, particle mass emissions decreased from 6 +/- 1 mg/hp-hr before regeneration to 3 +/- 2 mg/hp-hr after regeneration. This indicates that nanoparticles with diameters less than 50 nm may have been emitted after regeneration because these particles contribute little to the total mass. Overall, average particle emission reductions of 95% by mass and 10,000-fold by number concentration after 4 yr of use provided evidence of the durability of a field-aged DPF. In contrast to previous reports for new DPFs in which elevated number concentrations occurred during the first 200 sec of a transient cycle, the number concentration emissions were elevated during the second half of the heavy-duty Federal Test Procedure (FTP) when high speed was sustained. This information is relevant for the analysis of mechanisms by which particles are emitted from field-aged DPFs.

Biodegradable Janus nanoparticles for local pulmonary delivery of hydrophilic and hydrophobic molecules to the lungs.

PubMed

Garbuzenko, Olga B; Winkler, Jennifer; Tomassone, M Silvina; Minko, Tamara

2014-11-04

The aim of the present work is to synthesize, characterize, and test self-assembled anisotropic or Janus particles designed to load anticancer drugs for lung cancer treatment by inhalation. The particles were synthesized using binary mixtures of biodegradable and biocompatible materials. The particles did not demonstrate cyto- and genotoxic effects. Janus particles were internalized by cancer cells and accumulated both in the cytoplasm and nuclei. After inhalation delivery, nanoparticles accumulated preferentially in the lungs of mice and retained there for at least 24 h. Two drugs or other biologically active components with substantially different aqueous solubility can be simultaneously loaded in two-phases (polymer-lipid) of these nanoparticles. In the present proof-of-concept investigation, the particles were loaded with two anticancer drugs: doxorubicin and curcumin as model anticancer drugs with relatively high and low aqueous solubility, respectively. However, there are no obstacles for loading any hydrophobic or hydrophilic chemical agents. Nanoparticles with dual load were used for their local inhalation delivery directly to the lungs of mice with orthotopic model of human lung cancer. In vivo experiments showed that the selected nanoparticles with two anticancer drugs with different mechanisms of action prevented progression of lung tumors. It should be stressed that anticancer effects of the combined treatment with two anticancer drugs loaded in the same nanoparticle significantly exceeded the effect of either drug loaded in similar nanoparticles alone.

Online single particle measurement of fireworks pollution during Chinese New Year in Nanning.

PubMed

Li, Jingyan; Xu, Tingting; Lu, Xiaohui; Chen, Hong; Nizkorodov, Sergey A; Chen, Jianmin; Yang, Xin; Mo, Zhaoyu; Chen, Zhiming; Liu, Huilin; Mao, Jingying; Liang, Guiyun

2017-03-01

Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO 2 , coarse mode, and accumulation mode (100-500nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO 3 - ) followed by an increase of sulfate peaks (97HSO 4 - +96SO 4 - ) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO 2 on particles. High concentration of gaseous SO 2 , high relative humidity and high particle loading likely promoted SO 2 oxidation. Secondary nitrate formed through gas-phase oxidation of NO 2 to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays. Copyright © 2016. Published by Elsevier B.V.

Dorzolamide Loaded Niosomal Vesicles: Comparison of Passive and Remote Loading Methods.

PubMed

Hashemi Dehaghi, Mohadeseh; Haeri, Azadeh; Keshvari, Hamid; Abbasian, Zahra; Dadashzadeh, Simin

2017-01-01

Glaucoma is a common progressive eye disorder and the treatment strategies will benefit from nanoparticulate delivery systems with high drug loading and sustained delivery of intraocular pressure lowering agents. Niosomes have been reported as a novel approach to improve drug low corneal penetration and bioavailability characteristics. Along with this, poor entrapment efficiency of hydrophilic drug in niosomal formulation remains as a major formulation challenge. Taking this perspective into consideration, dorzolamide niosomes were prepared employing two different loading methodologies (passive and remote loading methods) and the effects of various formulation variables (lipid to drug ratio, cholesterol percentage, drug concentration, freeze/thaw cycles, TPGS content, and external and internal buffer molarity and pH) on encapsulation efficiency were assessed. Encapsulation of dorzolamide within niosomes increased remarkably by the incorporation of higher cholesterol percentage as well as increasing the total lipid concentration. Remote loading method showed higher efficacy for drug entrapment compared to passive loading technique. Incorporation of TPGS in bilayer led to decrease in EE; however, retarded drug release rate. Scanning electron microscopy (SEM) studies confirmed homogeneous particle distribution, and spherical shape with smooth surface. In conclusion, the highest encapsulation can be obtained using phosphate gradient method and 50% cholesterol in Span 60 niosomal formulation.

Effects of particulate radiation on premixed gas flames

NASA Technical Reports Server (NTRS)

Abbud-Madrid, Angel; Ronney, Paul D.

1993-01-01

Observations of the effect of the addition of fine solid particles to weakly combustible methane-air mixtures are reported. Burning rates, pressure rise, and thermal characteristics are found to exhibit nonmonotonic trends with increasing particle loading. These results are interpreted in terms of the effects of augmentation of radiant loss at small particle loadings and re-absorption of emitted radiation at larger loadings. It is suggested that in sufficiently large systems, flammability limits might not exist because of this reabsorption effect.

Sulfur driven nucleation mode formation in diesel exhaust under transient driving conditions.

PubMed

Karjalainen, Panu; Rönkkö, Topi; Pirjola, Liisa; Heikkilä, Juha; Happonen, Matti; Arnold, Frank; Rothe, Dieter; Bielaczyc, Piotr; Keskinen, Jorma

2014-02-18

Sulfur driven diesel exhaust nucleation particle formation processes were studied in an aerosol laboratory, on engine dynamometers, and on the road. All test engines were equipped with a combination of a diesel oxidation catalyst (DOC) and a partial diesel particulate filter (pDPF). At steady operating conditions, the formation of semivolatile nucleation particles directly depended on SO2 conversion in the catalyst. The nucleation particle emission was most significant after a rapid increase in engine load and exhaust gas temperature. Results indicate that the nucleation particle formation at transient driving conditions does not require compounds such as hydrocarbons or sulfated hydrocarbons, however, it cannot be explained only by the nucleation of sulfuric acid. A real-world exhaust study with a heavy duty diesel truck showed that the nucleation particle formation occurs even with ultralow sulfur diesel fuel, even at downhill driving conditions, and that nucleation particles can contribute 60% of total particle number emissions. In general, due to sulfur storage and release within the exhaust aftertreatment systems and transients in driving, emissions of nucleation particles can even be the dominant part of modern diesel vehicle exhaust particulate number emissions.

Bed material transport in the Virgin River, Utah

USGS Publications Warehouse

Andrews, E.D.

2000-01-01

Detailed information concerning the rate and particle size distribution of bed material transport by streamflows can be very difficult and expensive to obtain, especially where peak streamflows are brief and bed material is poorly sorted, including some very large boulders. Such streams, however, are common in steep, arid watersheds. Any computational approach must consider that (1) only the smaller particle sizes present on the streambed move even during large floods and (2) the largest bed particles exert a significant form drag on the flow. Conventional methods that rely on a single particle size to estimate the skin friction shear stress acting on the mobile fraction of the bed material perform poorly. Instead, for this study, the skin friction shear stress was calculated for the observed range of streamflows by calculating the form drag exerted on the reach‐averaged flow field by all particle sizes. Suspended and bed load transported rates computed from reach‐averaged skin friction shear stress are in excellent agreement with measured transport rates. The computed mean annual bed material load, including both bed load and suspended load, of the East Fork Virgin River for the water years 1992‐1996 was approximately 1.3×10 5 t. A large portion of the bed material load consists of sand‐sized particles, 0.062–1.0 mm in diameter, that are transported in suspension. Such particles, however, constituted only 10% of the surface bed material and less than 25% of the subsurface bed material. The mean annual quantity of bed load transported was 1060 t/yr with a median size of 15 mm.

Contributions of wastewater, runoff and sewer deposit erosion to wet weather pollutant loads in combined sewer systems.

PubMed

Gasperi, J; Gromaire, M C; Kafi, M; Moilleron, R; Chebbo, G

2010-12-01

An observatory of urban pollutants was created in Paris for the purpose of assessing the dynamics of wastewater and wet weather flow (WW and WWF) pollutant loads within combined sewers. This observatory is composed of six urban catchments, covering land areas ranging in size from 42 ha to 2581 ha. For a wide array of parameters including total suspended solids (TSS), chemical and biochemical oxygen demand (COD and BOD(5)), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), heavy metals (Cu and Zn) and polycyclic aromatic hydrocarbons (PAHs), this article is intended to evaluate the contributions of wastewater, runoff and in-sewer processes to WWF pollutant loads through the use of an entry-exit mass balance approach. To achieve this objective, a total of 16 rain events were sampled on these sites between May 2003 and February 2006. This study has confirmed that at the considered catchment scale (i.e. from 42 ha to 2581 ha) the production and transfer processes associated with WWF pollutant loads do not vary with basin scale. Entry-exit chemical mass balances over all catchments and for a large number of rain events indicate that wastewater constitutes the main source of organic and nitrogenous pollution, while runoff is the predominant source of Zn. For Cu, PAHs and TSS, the calculation underscores the major role played by in-sewer processes, specifically by sediment erosion, as a source of WWF pollution. A significant loss of dissolved metals was also observed during their transfer within the sewer network, likely as a consequence of the adsorption of dissolved metals on TSS and/or on sewer deposits. Moreover, the nature of eroded particles was examined and compared to the various sewer deposits. This comparison has highlighted that such particles exhibit similar organic and PAH contents to those measured in the organic layer, thus suggesting that the deposit eroded during a wet weather period is organic and of a nature comparable to the organic layer. Despite the extent of initial field investigations, no organic deposit was observed to be present on sewer lines within the catchments, which implies that this organic deposit is probably present in another form or to be found elsewhere in the main trunks. Copyright © 2010 Elsevier Ltd. All rights reserved.

PLGA/PFC particles loaded with gold nanoparticles as dual contrast agents for photoacoustic and ultrasound imaging

NASA Astrophysics Data System (ADS)

Wang, Yan J.; Strohm, Eric M.; Sun, Yang; Niu, Chengcheng; Zheng, Yuanyi; Wang, Zhigang; Kolios, Michael C.

2014-03-01

Phase-change contrast agents consisting of a perfluorocarbon (PFC) liquid core stabilized by a lipid, protein, or polymer shell have been proposed for a variety of clinical applications. Previous work has demonstrated that vaporization can be induced by laser irradiation through optical absorbers incorporated inside the droplet. In this study, Poly-lactide-coglycolic acid (PLGA) particles loaded with PFC liquid and silica-coated gold nanoparticles (GNPs) were developed and characterized using photoacoustic (PA) methods. Microsized PLGA particles were loaded with PFC liquid and GNPs (14, 35, 55nm each with a 20nm silica shell) using a double emulsion method. The PA signal intensity and optical vaporization threshold were investigated using a 375 MHz transducer and a focused 532-nm laser (up to 450-nJ per pulse). The laser-induced vaporization threshold energy decreased with increasing GNP size. The vaporization threshold was 850, 690 and 420 mJ/cm2 for 5μm-sized PLGA particles loaded with 14, 35 and 55 nm GNPs, respectively. The PA signal intensity increased as the laser fluence increased prior to the vaporization event. This trend was observed for all particles sizes. PLGA particles were then incubated with MDA-MB-231 breast cancer cells for 6 hours to investigate passive targeting, and the vaporization of the PLGA particles that were internalized within cells. The PLGA particles passively internalized by MDA cells were visualized via confocal fluorescence imaging. Upon PLGA particle vaporization, bubbles formed inside the cells resulting in cell destruction. This work demonstrates that GNPs-loaded PLGA/PFC particles have potential as PA theranostic agents in PA imaging and optically-triggered drug delivery systems.

Characterisation of diesel particulate emission from engines using commercial diesel and biofuels

NASA Astrophysics Data System (ADS)

Ajtai, T.; Pintér, M.; Utry, N.; Kiss-Albert, G.; Gulyás, G.; Pusztai, P.; Puskás, R.; Bereczky, Á.; Szabados, Gy.; Szabó, G.; Kónya, Z.; Bozóki, Z.

2016-06-01

In this paper, the number concentration and the size distribution of diluted diesel exhaust particulate matter were measured at three different engine operating points in the speed-load range of the engine as follows: 1600 rpm; 50% load, 1900 rpm; 25% load, 1900 rpm; 75% load, adopted from the UN ECE Vehicle Regulation no. 49 (Revision 2) test protocol using pure diesel and biodiesel fuels, as well as their controlled blends. The emitted particulate assembly had lognormal size distribution in the accumulation mode regardless of the engine operational condition and the type of fuel. The total number and volume concentration emitted by the diesel engine decreased with increasing revolution per minute and rated torque in case of all the fuel types. The mixing ratio of the fuels did not linearly affect the total emission but had a minimum at 75% biodiesel content. We also studied the thermal evolution of the emitted particulates using a specially designed thermodenuder (TD) heated at specific temperatures (50 °C, 120 °C, and 250 °C). The first transition, when the temperature was increased from 50 °C to 120 °C resulted in lower number concentrations with small relative shifts of the peak position. However, in case of the second transition, when the temperature reached 250 °C the individual volatile particulates adsorbed onto the surface of soot particles were completely or partly vaporised resulting in lower total number concentrations with a substantial shift in peak position.

Quantification of microwave-induced amorphization of celecoxib in PVP tablets using transmission Raman spectroscopy.

PubMed

Edinger, Magnus; Knopp, Matthias Manne; Kerdoncuff, Hugo; Rantanen, Jukka; Rades, Thomas; Löbmann, Korbinian

2018-05-30

In this study, the influence of drug load on the microwave-induced amorphization of celecoxib (CCX) in polyvinylpyrrolidone (PVP) tablets was investigated using quantitative transmission Raman spectroscopy. A design of experiments (DoE) setup was applied for developing the quantitative model using two factors: drug load (10, 30, and 50% w/w) and amorphous fraction (0, 25, 50, 75 and 100%). The data was modeled using partial least-squares (PLS) regression and resulted in a robust model with a root mean-square error of prediction of 2.5%. The PLS model was used to study the amorphization kinetics of CCX-PVP tablets with different drug content (10, 20, 30, 40 and 50% w/w). For this purpose, transition Raman spectra were collected in 60 s intervals over a total microwave time of 10 min with an energy input of 1000 W. Using the quantitative model it was possible to measure the amorphous fraction of the tablets and follow the amorphization as a function of microwaving time. The relative amorphous fraction of CCX increased with increasing microwaving time and decreasing drug load, hence 90 ± 7% of the drug was amorphized in the tablets with 10% drug load whereas only 31 ± 7% of the drug was amorphized in the 50% CCX tablets. It is suggested that the degree of amorphization depends on drug loading. The likelihood of drug particles being in direct contact with the polymer PVP is a requirement for the dissolution of the drug into the polymer upon microwaving, and this is reduced with increasing drug load. This was further supported by polarized light microscopy that revealed evidence of crystalline particles and clusters in all the microwaved tablets. Copyright © 2018 Elsevier B.V. All rights reserved.

Particulate systems based on pectin/chitosan association for the delivery of manuka honey components and platelet lysate in chronic skin ulcers.

PubMed

Tenci, Marika; Rossi, Silvia; Bonferoni, Maria Cristina; Sandri, Giuseppina; Boselli, Cinzia; Di Lorenzo, Arianna; Daglia, Maria; Icaro Cornaglia, Antonia; Gioglio, Luciana; Perotti, Cesare; Caramella, Carla; Ferrari, Franca

2016-07-25

The aim of the present work was the development of a powder formulation for the delivery of manuka honey (MH) bioactive components and platelet lysate (PL) in chronic skin ulcers. In particular pectin (PEC)/chitosan (CS) particles were prepared by ionotropic gelation in the presence of calcium chloride and subsequently characterized for particle size, hydration properties and mechanical resistance. Different experimental conditions (calcium chloride and CS concentrations; rest time in the cationic solution) were considered in order to obtain particles characterized by optimal size, hydration properties and mechanical resistance. Two different fractions of MH were examined: one (Fr1), rich in methylglyoxal and the other (Fr2), rich in polyphenols. Particles were loaded with Fr1, fraction able to enhance in vitro proliferation of human fibroblasts, and with PL. The presence of CS in Fr1-loaded particles produced an improvement in cell proliferation. Moreover, PL loading into particles did not affect the biological activity of the hemoderivative. In vivo efficacy of PL- and Fr1-loaded particles was evaluated on a rat wound model. Both treatments markedly increased wound healing to the same extent. Copyright © 2016 Elsevier B.V. All rights reserved.

Inductively heated shape memory polymer for the magnetic actuation of medical devices.

PubMed

Buckley, Patrick R; McKinley, Gareth H; Wilson, Thomas S; Small, Ward; Benett, William J; Bearinger, Jane P; McElfresh, Michael W; Maitland, Duncan J

2006-10-01

Presently, there is interest in making medical devices such as expandable stents and intravascular microactuators from shape memory polymer (SMP). One of the key challenges in realizing SMP medical devices is the implementation of a safe and effective method of thermally actuating various device geometries in vivo. A novel scheme of actuation by Curie-thermoregulated inductive heating is presented. Prototype medical devices made from SMP loaded with nickel zinc ferrite ferromagnetic particles were actuated in air by applying an alternating magnetic field to induce heating. Dynamic mechanical thermal analysis was performed on both the particle-loaded and neat SMP materials to assess the impact of the ferrite particles on the mechanical properties of the samples. Calorimetry was used to quantify the rate of heat generation as a function of particle size and volumetric loading of ferrite particles in the SMP. These tests demonstrated the feasibility of SMP actuation by inductive heating. Rapid and uniform heating was achieved in complex device geometries and particle loading up to 10% volume content did not interfere with the shape recovery of the SMP.

Universal characteristics of particle shape evolution by bed-load chipping.

PubMed

Novák-Szabó, Tímea; Sipos, András Árpád; Shaw, Sam; Bertoni, Duccio; Pozzebon, Alessandro; Grottoli, Edoardo; Sarti, Giovanni; Ciavola, Paolo; Domokos, Gábor; Jerolmack, Douglas J

2018-03-01

River currents, wind, and waves drive bed-load transport, in which sediment particles collide with each other and Earth's surface. A generic consequence is impact attrition and rounding of particles as a result of chipping, often referred to in geological literature as abrasion. Recent studies have shown that the rounding of river pebbles can be modeled as diffusion of surface curvature, indicating that geometric aspects of impact attrition are insensitive to details of collisions and material properties. We present data from fluvial, aeolian, and coastal environments and laboratory experiments that suggest a common relation between circularity and mass attrition for particles transported as bed load. Theory and simulations demonstrate that universal characteristics of shape evolution arise because of three constraints: (i) Initial particles are mildly elongated fragments, (ii) particles collide with similarly-sized particles or the bed, and (iii) collision energy is small enough that chipping dominates over fragmentation but large enough that sliding friction is negligible. We show that bed-load transport selects these constraints, providing the foundation to estimate a particle's attrition rate from its shape alone in most sedimentary environments. These findings may be used to determine the contribution of attrition to downstream fining in rivers and deserts and to infer transport conditions using only images of sediment grains.

Metals and bacteria partitioning to various size particles in Ballona Creek storm water runoff.

PubMed

Brown, Jeffrey S; Stein, Eric D; Ackerman, Drew; Dorsey, John H; Lyon, Jessica; Carter, Patrick M

2013-02-01

Many storm water best management practice (BMP) devices function primarily by capturing particulate matter to take advantage of the well-documented association between storm water particles and pollutants. The hydrodynamic separation or settling methods used by most BMP devices are most effective at capturing medium to large particles; however, these may not be the most predominant particles associated with urban runoff. The present study examined particle size distribution in storm water runoff from an urban watershed in southern California and investigated the pollutant-particle associations of metals (Cu, Pb, Ni, and Zn) and bacteria (enterococci and Escherichia coli). During small storm events (≤0.7 cm rain), the highest concentration of pollutants were associated with a <6-µm filter fraction, which accounted for 70% of the per storm contaminant mass but made up more than 20% of the total particle mass. The pollutant-particle association changed with storm size. Most pollutant mass was associated with >35 µm size particles during a 5-cm rain event. These results suggest that much of the contaminant load in storm water runoff will not be captured by the most commonly used BMP devices, because most of these devices (e.g., hydrodynamic separators) are unable to capture particles smaller than 75 µm. Copyright © 2012 SETAC.

Effects of particle size, helium gas pressure and microparticle dose on the plasma concentration of indomethacin after bombardment of indomethacin-loaded poly-L-lactic acid microspheres using a Helios gun system.

PubMed

Uchida, Masaki; Natsume, Hideshi; Kobayashi, Daisuke; Sugibayashi, Kenji; Morimoto, Yasunori

2002-05-01

We investigated the effects of the particle size of indomethacin-loaded poly-L-lactic acid microspheres (IDM-loaded PLA MS), the helium pressure used to accelerate the particles, and the bombardment dose of PLA MS on the plasma concentration of IDM after bombarding with IDM-loaded PLA MS of different particle size ranges, 20-38, 44-53 and 75-100 microm, the abdomen of hairless rats using the Helios gene gun system (Helios gun system). Using larger particles and a higher helium pressure, produced an increase in the plasma IDM concentration and the area under the plasma concentration-time curve (AUC) and resultant F (relative bioavailability with respect to intracutaneous injection) of IDM increased by an amount depending on the particle size and helium pressure. Although a reduction in the bombardment dose led to a decrease in C(max) and AUC, F increased on decreasing the bombardment dose. In addition, a more efficient F was obtained after bombarding with IDM-loaded PLA MS of 75-100 microm in diameter at each low dose in different sites of the abdomen compared with that after bolus bombardment with a high dose (dose equivalent). These results suggest that the bombardment injection of drug-loaded microspheres by the Helios gun system is a very useful tool for delivering a variety of drugs in powder form into the skin and systemic circulation.

The influence of marine microbial activities on aerosol production: A laboratory mesocosm study

NASA Astrophysics Data System (ADS)

Alpert, Peter A.; Kilthau, Wendy P.; Bothe, Dylan W.; Radway, JoAnn C.; Aller, Josephine Y.; Knopf, Daniel A.

2015-09-01

The oceans cover most of the Earth's surface, contain nearly half the total global primary biomass productivity, and are a major source of atmospheric aerosol particles. Here we experimentally investigate links between biological activity in seawater and sea spray aerosol (SSA) flux, a relationship of potential significance for organic aerosol loading and cloud formation over the oceans and thus for climate globally. Bubbles were generated in laboratory mesocosm experiments either by recirculating impinging water jets or glass frits. Experiments were conducted with Atlantic Ocean seawater collected off the eastern end of Long Island, NY, and with artificial seawater containing cultures of bacteria and phytoplankton Thalassiosira pseudonana, Emiliania huxleyi, and Nannochloris atomus. Changes in SSA size distributions occurred during all phases of bacterial and phytoplankton growth, as characterized by cell concentrations, dissolved organic carbon, total particulate carbon, and transparent exopolymer particles (gel-forming polysaccharides representing a major component of biogenic exudate material). Over a 2 week growth period, SSA particle concentrations increased by a factor of less than 2 when only bacteria were present and by a factor of about 3 when bacteria and phytoplankton were present. Production of jet-generated SSA particles of diameter less than 200 nm increased with time, while production of all particle diameters increased with time when frits were used. The implications of a marine biological activity dependent SSA flux are discussed.

Improving Extraction Ion Diode Operation By Introducing An Axial Load

NASA Astrophysics Data System (ADS)

Vesey, R. A.; Desjarlais, M. P.; Greenly, J. B.

1997-11-01

Recent ion diode experiments at Cornell have shown that the presence of an axial current load (in this case an inductive voltage monitor) significantly reduced the electron loss to the anode with some indication of a simultaneous reduction in the beam divergence(J. B. Greenly et al., this conference.). The QUICKSILVER 3D particle-in-cell code has been used to simulate axial loads on the SABRE (6 MV, 250 kA) ion diode at Sandia. Initial results show that an axial load drawing 30% of the total diode current reduces the electron loss by 55% while reducing the ion current by just 15%. With an increased applied magnetic field, the electron loss to the anode face is completely suppressed and ion mode oscillations are strongly damped, albeit with a 40% reduction in the ion current. These results show that further scoping simulations are necessary to understand the mechanism involved and to refine the operating parameters (axial current, B-field, A-K gap) for optimum performance.

Aerosol Optical Properties over Northwestern European Seas

NASA Astrophysics Data System (ADS)

Avgousta Floutsi, Athina; Korras Carraca, Marios Bruno; Matsoukas, Christos; Riva, Riccardo; Biskos, George

2017-04-01

Atmospheric aerosols, both natural and anthropogenic, can affect the regional and global climate through their direct, indirect, and semi-direct effects on the radiative energy budget of the Earth-atmosphere system. In order to quantify these effects it is necessary to determine the aerosol load. An effective way to do this is by measuring the aerosol optical depth (AOD). Besides AOD, the Fine mode Fraction (AOD of particles smaller than 1 μm / total AOD, FF) is a useful parameter for the characterization of the aerosol and provides a good proxy for particle size. In this study, we investigate the spatial and temporal variability of the AOD and FF over the Western and Northwestern European Seas (43° N - 67° N, 10° W - 31° E), where significant sources of both natural and anthropogenic particles are located. Anthropogenic particles (mostly fine mode) originate from ship activity, or from urban-industrial and biomass-burning processes in the European countries. The natural, coarse mode particles are primarily sea salt. The study is performed using Collection 006 Level-3 mean daily aerosol data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board Aqua satellite, available in 1° × 1° resolution (ca. 100 km × 100 km) over the period 2002- 2014. Our results indicate significant spatial variability of the aerosol load over the study region. The highest AOD values (up to 0.32 on annual level) are observed over the English Channel and the coasts of the Netherlands and Germany. In these regions the highest FF values are also observed (up to 0.77), indicating a relatively large contribution of anthropogenic particles to the aerosol load. Offshore, both AOD and FF are lower compared to coastal regions, indicating the predominance of maritime aerosols (sea salt). The data also show a clear seasonal cycle, with larger aerosol load during spring and summer (AOD up to 0.60), and lower during autumn and winter (AOD up to 0.30). A similar pattern is observed for FF indicating a larger contribution of anthropogenic particles during spring and summer compared to autumn and winter. The highest FF values (up to 0.80- 0.85) are observed over the Baltic Sea during summer while year-round the lowest values are observed in remote maritime areas, mostly in the northern part of our study region, highlighting the predominance of sea salt particles. The AOD exhibits a generally decreasing trend (slope between -0.18 to 0.05 per decade). Positive values are observed over the northwestern ocean areas (sea salt dominated), while over most of our study region the slope is of the order of -0.02 to -0.05 per decade. These trends are possibly associated with a reduction of the anthropogenic emissions.

Highway-runoff quality, and treatment efficiencies of a hydrodynamic-settling device and a stormwater-filtration device in Milwaukee, Wisconsin

USGS Publications Warehouse

Horwatich, Judy A.; Bannerman, Roger T.; Pearson, Robert

2011-01-01

The treatment efficiencies of two prefabricated stormwater-treatment devices were tested at a freeway site in a high-density urban part of Milwaukee, Wisconsin. One treatment device is categorized as a hydrodynamic-settling device (HSD), which removes pollutants by sedimentation and flotation. The other treatment device is categorized as a stormwater-filtration device (SFD), which removes pollutants by filtration and sedimentation. During runoff events, flow measurements were recorded and water-quality samples were collected at the inlet and outlet of each device. Efficiency-ratio and summation-of-load (SOL) calculations were used to estimate the treatment efficiency of each device. Event-mean concentrations and loads that were decreased by passing through the HSD include total suspended solids (TSS), suspended sediment (SS), total phosphorus (TP), total copper (TCu), and total zinc (TZn). The efficiency ratios for these constituents were 42, 57, 17, 33, and 23 percent, respectively. The SOL removal rates for these constituents were 25, 49, 10, 27, and 16 percent, respectively. Event-mean concentrations and loads that increased by passing through the HSD include chloride (Cl), total dissolved solids (TDS), and dissolved zinc (DZn). The efficiency ratios for these constituents were -347, -177, and 20 percent, respectively. Four constituents—dissolved phosphorus (DP), chemical oxygen demand (COD), total polycyclic aromatic hydrocarbon (PAH), and dissolved copper (DCu)—are not included in the list of computed efficiency ratio and SOL because the variability between sampled inlet and outlet pairs were not significantly different. Event-mean concentrations and loads that decreased by passing through the SFD include TSS, SS, TP, DCu, TCu, DZn, TZn, and COD. The efficiency ratios for these constituents were 59, 90, 40, 21, 66, 23, 66, and 18, respectively. The SOLs for these constituents were 50, 89, 37, 19, 60, 20, 65, and 21, respectively. Two constituents—DP and PAH—are not included in the lists of computed efficiency ratio and SOL because the variability between sampled inlet and outlet pairs were not significantly different. Similar to the HSD, the average efficiency ratios and SOLs for TDS and Cl were negative. Flow rates, high concentrations of SS, and particle-size distributions (PSD) can affect the treatment efficacies of the two devices. Flow rates equal to or greater than the design flow rate of the HSD had minimal or negative removal efficiencies for TSS and SS loads. Similar TSS removal efficiencies were observed at the SFD, but SS was consistently removed throughout the flow regime. Removal efficiencies were high for both devices when concentrations of SS and TSS approached 200 mg/L. A small number of runoff events were analyzed for PSD; the average sand content at the HSD was 33 percent and at the SFD was 71 percent. The 71-percent sand content may reflect the 90-percent removal efficiency of SS at the SFD. Particles retained at the bottom of both devices were largely sand-size or greater.

Effect of climate change on stormwater runoff characteristics and treatment efficiencies of stormwater retention ponds: a case study from Denmark using TSS and Cu as indicator pollutants.

PubMed

Sharma, Anitha Kumari; Vezzaro, Luca; Birch, Heidi; Arnbjerg-Nielsen, Karsten; Mikkelsen, Peter Steen

2016-01-01

This study investigated the potential effect of climate changes on stormwater pollution runoff characteristics and the treatment efficiency of a stormwater retention pond in a 95 ha catchment in Denmark. An integrated dynamic stormwater runoff quality and treatment model was used to simulate two scenarios: one representing the current climate and another representing a future climate scenario with increased intensity of extreme rainfall events and longer dry weather periods. 100-year long high-resolution rainfall time series downscaled from regional climate model projections were used as input. The collected data showed that total suspended solids (TSS) and total copper (Cu) concentrations in stormwater runoff were related to flow, rainfall intensity and antecedent dry period. Extreme peak intensities resulted in high particulate concentrations and high loads but did not affect dissolved Cu concentrations. The future climate simulations showed an increased frequency of higher flows and increased total concentrations discharged from the catchment. The effect on the outlet from the pond was an increase in the total concentrations (TSS and Cu), whereas no major effect was observed on dissolved Cu concentrations. Similar results are expected for other particle bound pollutants including metals and slowly biodegradable organic substances such as PAH. Acute toxicity impacts to downstream surface waters seem to be only slightly affected. A minor increase in yearly loads of sediments and particle-bound pollutants is expected, mainly caused by large events disrupting the settling process. This may be important to consider for the many stormwater retention ponds existing in Denmark and across the world.

The sustained-release behavior and in vitro and in vivo transfection of pEGFP-loaded core-shell-structured chitosan-based composite particles

PubMed Central

Wang, Yun; Lin, Fu-xing; Zhao, Yu; Wang, Mo-zhen; Ge, Xue-wu; Gong, Zheng-xing; Bao, Dan-dan; Gu, Yu-fang

2014-01-01

Novel submicron core-shell-structured chitosan-based composite particles encapsulated with enhanced green fluorescent protein plasmids (pEGFP) were prepared by complex coacervation method. The core was pEGFP-loaded thiolated N-alkylated chitosan (TACS) and the shell was pH- and temperature-responsive hydroxybutyl chitosan (HBC). pEGFP-loaded TACS-HBC composite particles were spherical, and had a mean diameter of approximately 120 nm, as measured by transmission electron microscopy and particle size analyzer. pEGFP showed sustained release in vitro for >15 days. Furthermore, in vitro transfection in human embryonic kidney 293T and human cervix epithelial cells, and in vivo transfection in mice skeletal muscle of loaded pEGFP, were investigated. Results showed that the expression of loaded pEGFP, both in vitro and in vivo, was slow but could be sustained over a long period. pEGFP expression in mice skeletal muscle was sustained for >60 days. This work indicates that these submicron core-shell-structured chitosan-based composite particles could potentially be used as a gene vector for in vivo controlled gene transfection. PMID:25364253

The sustained-release behavior and in vitro and in vivo transfection of pEGFP-loaded core-shell-structured chitosan-based composite particles.

PubMed

Wang, Yun; Lin, Fu-xing; Zhao, Yu; Wang, Mo-zhen; Ge, Xue-wu; Gong, Zheng-xing; Bao, Dan-dan; Gu, Yu-fang

2014-01-01

Novel submicron core-shell-structured chitosan-based composite particles encapsulated with enhanced green fluorescent protein plasmids (pEGFP) were prepared by complex coacervation method. The core was pEGFP-loaded thiolated N-alkylated chitosan (TACS) and the shell was pH- and temperature-responsive hydroxybutyl chitosan (HBC). pEGFP-loaded TACS-HBC composite particles were spherical, and had a mean diameter of approximately 120 nm, as measured by transmission electron microscopy and particle size analyzer. pEGFP showed sustained release in vitro for >15 days. Furthermore, in vitro transfection in human embryonic kidney 293T and human cervix epithelial cells, and in vivo transfection in mice skeletal muscle of loaded pEGFP, were investigated. Results showed that the expression of loaded pEGFP, both in vitro and in vivo, was slow but could be sustained over a long period. pEGFP expression in mice skeletal muscle was sustained for >60 days. This work indicates that these submicron core-shell-structured chitosan-based composite particles could potentially be used as a gene vector for in vivo controlled gene transfection.

Role of the primary silicon particle on the dry sliding wear of hypereutectic aluminium-silicon alloy A390

NASA Astrophysics Data System (ADS)

Lee, Jung-Moo; Kang, Suk-Bong; Yoon, Sang-Chul

1999-07-01

The wear behavior of hypereutectic aluminium-silicon alloy A390 was investigated using a pin-on-disc wear machine under dry sliding conditions. The wear tests were performed within a load range of 10 to 300N at a constant sliding velocity of 0.5 m/sec. The microstructural and compositional changes that took place during wear were characterized by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray analysis (EDXA) system. Based on the metallographic observations the role of the primary silicon particles was suggested. In a low pressure region, primary silicon particles supported the applied load and wear occurred mainly in the matrix. Thus the wear loss did not show much variation with the applied load. In the mid-load range, primary silicon particles did not yet fracture and thus supported the applied load in part. Transition from oxidative to metallic wear occurs mainly in the matrix and the increase of wear loss becomes sharper than that in a low pressure region. In the high pressure region, the fractures of primary silicon Particles occurred and wear loss increased sharply.

Response of Jupiter's Aurora to Plasma Mass Loading Rate Monitored by the Hisaki Satellite During Io's Volcanic Event

NASA Astrophysics Data System (ADS)

Kimura, T.; Yoshioka, K.; Tsuchiya, F.; Hiraki, Y.; Tao, C.; Murakami, G.; Yamazaki, A.; Fujimoto, M.; Badman, S. V.; Delamere, P. A.; Bagenal, F.

2016-12-01

Plasma production and transfer processes in the planetary and stellar magnetospheres are essential for understanding the space environments around the celestial bodies. It is hypothesized that the mass of plasma loaded from Io's volcano to Jupiter's rotating magnetosphere is recurrently ejected as blobs from the distant tail region of the magnetosphere. The plasma ejections are possibly triggered by the magnetic reconnections, which are followed by the particle energization, bursty planetward plasma flow, and resultant auroral emissions. They are referred to as the 'energetic events'. However, there has been no evidence that the plasma mass loading actually causes the energetic events because of lack of the simultaneous observation of them. This study presents that the recurrent transient auroras, which are possibly representative for the energetic events, are closely associated with the mass loading. Continuous monitoring of the aurora and Io plasma torus indicates onset of the recurrent auroras when accumulation of the loaded plasma mass reaches the canonical total mass of the magnetosphere. This onset condition implies that the fully filled magnetosphere overflows the plasma mass accompanying the energetic events.

3D finite element modelling of force transmission and particle fracture of sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imseeh, Wadi H.; Alshibli, Khalid A.

Global compressive loading of granular media causes rearrangements of particles into a denser configuration. Under 1D compression, researchers observed that particles initially translate and rotate which lead to more contacts between particles and the development of force chains to resist applied loads. Particles within force chains resist most of the applied loads while neighbor particles provide lateral support to prevent particles within force chains from buckling. Several experimental and numerical models have been proposed in the literature to characterize force chains within granular materials. This paper presents a 3D finite element (FE) model that simulates 1D compression experiment on F-75more » Ottawa sand. The FE mesh of particles closely matched 3D physical shape of sand particles that were acquired using 3D synchrotron micro-computed tomography (SMT) technique. The paper presents a quantitative assessment of the model, in which evolution of force chains, fracture modes, and stress-strain relationships showed an excellent agreement with experimental measurements reported by Cil et al. Alshibli (2017).« less

Analysis of heavy metals in road-deposited sediments.

PubMed

Herngren, Lars; Goonetilleke, Ashantha; Ayoko, Godwin A

2006-07-07

Road-deposited sediments were analysed for heavy metal concentrations at three different landuses (residential, industrial, commercial) in Queensland State, Australia. The sediments were collected using a domestic vacuum cleaner which was proven to be highly efficient in collecting sub-micron particles. Five particle sizes were analysed separately for eight heavy metal elements (Zn, Fe, Pb, Cd, Cu, Cr, Al and Mn). At all sites, the maximum concentration of the heavy metals occurred in the 0.45-75 microm particle size range, which conventional street cleaning services do not remove efficiently. Multicriteria decision making methods (MCDM), PROMETHEE and GAIA, were employed in the data analysis. PROMETHEE, a non-parametric ranking analysis procedure, was used to rank the metal contents of the sediments sampled at each site. The most polluted site and particle size range were the industrial site and the 0.45-75 microm range, respectively. Although the industrial site displayed the highest metal concentrations, the highest heavy metal loading coincided with the highest sediment load, which occurred at the commercial site. GAIA, a special form of principal component analysis, was applied to determine correlations between the heavy metals and particle size ranges and also to assess possible correlation with total organic carbon (TOC). The GAIA-planes revealed that irrespective of the site, most of the heavy metals are adsorbed to sediments below 150 microm. A weak correlation was found between Zn, Mn and TOC at the commercial site. This could lead to higher bioavailability of these metals through complexation reactions with the organic species in the sediments.

Meso-Scale Modeling of Spall in a Heterogeneous Two-Phase Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Springer, Harry Keo

2008-07-11

The influence of the heterogeneous second-phase particle structure and applied loading conditions on the ductile spall response of a model two-phase material was investigated. Quantitative metallography, three-dimensional (3D) meso-scale simulations (MSS), and small-scale spall experiments provided the foundation for this study. Nodular ductile iron (NDI) was selected as the model two-phase material for this study because it contains a large and readily identifiable second- phase particle population. Second-phase particles serve as the primary void nucleation sites in NDI and are, therefore, central to its ductile spall response. A mathematical model was developed for the NDI second-phase volume fraction that accountedmore » for the non-uniform particle size and spacing distributions within the framework of a length-scale dependent Gaussian probability distribution function (PDF). This model was based on novel multiscale sampling measurements. A methodology was also developed for the computer generation of representative particle structures based on their mathematical description, enabling 3D MSS. MSS were used to investigate the effects of second-phase particle volume fraction and particle size, loading conditions, and physical domain size of simulation on the ductile spall response of a model two-phase material. MSS results reinforce existing model predictions, where the spall strength metric (SSM) logarithmically decreases with increasing particle volume fraction. While SSM predictions are nearly independent of applied load conditions at lower loading rates, which is consistent with previous studies, loading dependencies are observed at higher loading rates. There is also a logarithmic decrease in SSM for increasing (initial) void size, as well. A model was developed to account for the effects of loading rate, particle size, matrix sound-speed, and, in the NDI-specific case, the probabilistic particle volume fraction model. Small-scale spall experiments were designed and executed for the purpose of validating closely-coupled 3D MSS. While the spall strength is nearly independent of specimen thickness, the fragment morphology varies widely. Detailed MSS demonstrate that the interactions between the tensile release waves are altered by specimen thickness and that these interactions are primarily responsible for fragment formation. MSS also provided insights on the regional amplification of damage, which enables the development of predictive void evolution models.« less

Particle and Power Exhaust in EAST

NASA Astrophysics Data System (ADS)

Wang, Liang; Ding, Fang; Yu, Yaowei; Gan, Kaifu; Liang, Yunfeng; Xu, Guosheng; Xiao, Bingjia; Sun, Youwen; Luo, Guangnan; Gong, Xianzu; Hu, Jiansheng; Li, Jiangang; Wan, Baonian; Maingi, Rajesh; Guo, Houyang; Garofalo, Andrea; EAST Team

2017-10-01

A total power injection up to 0.3GJ has been achieved in EAST long pulse USN operation with ITER-like water-cooling W-monoblock divertor, which has steady-state power exhaust capability of 10 MWm-2. The peak temperature of W target saturated at t = 12 s to the value T 500oC and a heat flux 3MWm-2was maintained. Great efforts to reduce heat flux and accommodate particle exhaust simultaneously have been made towards long pulse of 102s time scale. By exploiting the observation of Pfirsch-Schlüter flow direction in the SOL, the Bt direction with Bx ∇B away from the W divertor (more particles favor outer target in USN) was adopted along with optimizing the strike point location near the pumping slot, to facilitate particle and impurity exhaust with the top cryo-pump. By tailoring the 3D divertor footprint through edge magnetic topology change, the heat load was dispersed widely and thus peak heat flux and W sputtering was well controlled. Active feedback control of total radiative power with neon seeding was achieved within frad = 17-35%, exhibiting further potential for heat flux reduction with divertor and edge radiation. Other heat flux handling techniques, including quasi snowflake configuration, will also be presented.

Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

NASA Technical Reports Server (NTRS)

Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.;

Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part II: Polyethylene Particles Decrease the Effect of Polycyclic Aromatic Hydrocarbons on Microorganisms.

PubMed

Kleinteich, Julia; Seidensticker, Sven; Marggrander, Nikolaj; Zarfl, Christiane

2018-02-07

Microplastic particles in terrestrial and aquatic ecosystems are currently discussed as an emerging persistent organic pollutant and as acting as a vector for hydrophobic chemicals. Microplastic particles may ultimately deposit and accumulate in soil as well as marine and freshwater sediments where they can be harmful to organisms. In this study, we tested the sensitivity of natural freshwater sediment bacterial communities (by genetic fingerprint) to exposure to microplastics (polyethylene, 2 and 20 mg/g sediment) and microplastics loaded with polycyclic aromatic hydrocarbons (PAHs, phenanthrene and anthracene), using a laboratory-based approach. After two weeks of incubation, the bacterial community composition from an unpolluted river section was altered by high concentrations of microplastics, whereas the community downstream of a wastewater treatment plant remained unchanged. Low microplastic concentrations loaded with phenanthrene or anthracene induced a less pronounced response in the sediment communities compared to the same total amount of phenanthrene or anthracene alone. In addition, biodegradation of the PAHs was reduced. This study shows, that microplastic can affect bacterial community composition in unpolluted freshwater sediments. Moreover, the results indicate that microplastics can serve as a vehicle for hydrophobic pollutants but bioavailability of the latter is reduced by the sorption to microplastics.

Microplastics Reduce Short-Term Effects of Environmental Contaminants. Part II: Polyethylene Particles Decrease the Effect of Polycyclic Aromatic Hydrocarbons on Microorganisms

PubMed Central

Kleinteich, Julia; Marggrander, Nikolaj; Zarfl, Christiane

2018-01-01

Microplastic particles in terrestrial and aquatic ecosystems are currently discussed as an emerging persistent organic pollutant and as acting as a vector for hydrophobic chemicals. Microplastic particles may ultimately deposit and accumulate in soil as well as marine and freshwater sediments where they can be harmful to organisms. In this study, we tested the sensitivity of natural freshwater sediment bacterial communities (by genetic fingerprint) to exposure to microplastics (polyethylene, 2 and 20 mg/g sediment) and microplastics loaded with polycyclic aromatic hydrocarbons (PAHs, phenanthrene and anthracene), using a laboratory-based approach. After two weeks of incubation, the bacterial community composition from an unpolluted river section was altered by high concentrations of microplastics, whereas the community downstream of a wastewater treatment plant remained unchanged. Low microplastic concentrations loaded with phenanthrene or anthracene induced a less pronounced response in the sediment communities compared to the same total amount of phenanthrene or anthracene alone. In addition, biodegradation of the PAHs was reduced. This study shows, that microplastic can affect bacterial community composition in unpolluted freshwater sediments. Moreover, the results indicate that microplastics can serve as a vehicle for hydrophobic pollutants but bioavailability of the latter is reduced by the sorption to microplastics. PMID:29414906

Box-Behnken study design for optimization of bicalutamide-loaded nanostructured lipid carrier: stability assessment.

PubMed

Kudarha, Ritu; Dhas, Namdev L; Pandey, Abhijeet; Belgamwar, Veena S; Ige, Pradum P

2015-01-01

Bicalutamide (BCM) is an anti-androgen drug used to treat prostate cancer. In this study, nanostructured lipid carriers (NLCs) were chosen as a carrier for delivery of BCM using Box-Behnken (BB) design for optimizing various quality attributes such as particle size and entrapment efficiency which is very critical for efficient drug delivery and high therapeutic efficacy. Stability of formulated NLCs was assessed with respect to storage stability, pH stability, hemolysis, protein stability, serum protein stability and accelerated stability. Hot high-pressure homogenizer was utilized for formulation of BCM-loaded NLCs. In BB response surface methodology, total lipid, % liquid lipid and % soya lecithin was selected as independent variable and particle size and %EE as dependent variables. Scanning electron microscopy (SEM) was done for morphological study of NLCs. Differential scanning calorimeter and X-ray diffraction study were used to study crystalline and amorphous behavior. Analysis of design space showed that process was robust with the particle size less than 200 nm and EE up to 78%. Results of stability studies showed stability of carrier in various storage conditions and in different pH condition. From all the above study, it can be concluded that NLCs may be suitable carrier for the delivery of BCM with respect to stability and quality attributes.

Comparison between the loading capacities of columns packed with partially and totally porous fine particles. What is the effective surface area available for adsorption?

PubMed

Gritti, Fabrice; Guiochon, Georges

2007-12-28

The adsorption isotherms of phenol, caffeine, insulin, and lysozyme were measured on two C(18)-bonded silica columns. The first one was packed with classical totally porous particles (3 microm Luna(2)-C(18)from Phenomenex, Torrance, CA, USA), the second one with shell particles (2.7 microm Halo-C(18) from Advanced Materials Technology, Wilmington, DE, USA). The measurements were made at room temperature (T=295+/-1K), using mainly frontal analysis (FA) and also elution by characteristic points (FACP) when necessary. The adsorption energy distributions (AEDs) were estimated by the iterative numerical expectation-maximization (EM) procedure and served to justify the choice of the best adsorption isotherm model for each compound. The best isotherm parameters were derived from either the best fit of the experimental data to a multi-Langmuir isotherm model (MLRA) or from the AED results (equilibrium constants and saturation capacities), when the convergence of the EM program was achieved. The experiments show than the loading capacity of the Luna column is more than twice that of the Halo column for low-molecular-weight compounds. This result was expected; it is in good agreement with the values of the accessible surface area of these two materials, which were calculated from the pore size volume distributions. The pore size volume distributions are validated by the excellent agreement between the calculated and measured exclusion volumes of polystyrene standards by inverse size exclusion chromatography (ISEC). In contrast, the loading capacity ratio of the two columns is 1.5 or less with insulin and lysozyme. This is due to a significant exclusion of these two proteins from the internal pore volumes of the two packing materials. This result raises the problem of the determination of the effective surface area of the packing material, particularly in the case of proteins. This area is about 40 and 30% of the total surface area for insulin and for lysozyme, respectively, based on the pore size volume distribution validated by the ISEC method. The ISEC experiments showed that the largest and the smallest mesopores have rather a cylindrical and a spherical shape, respectively, for both packing materials.

Selective anticancer activity of hydroxyapatite/chitosan-poly(d,l)-lactide-co-glycolide particles loaded with an androstane-based cancer inhibitor.

PubMed

Ignjatović, Nenad L; Penov-Gaši, Katarina M; Wu, Victoria M; Ajduković, Jovana J; Kojić, Vesna V; Vasiljević-Radović, Dana; Kuzmanović, Maja; Uskoković, Vuk; Uskoković, Dragan P

2016-12-01

In an earlier study we demonstrated that hydroxyapatite nanoparticles coated with chitosan-poly(d,l)-lactide-co-glycolide (HAp/Ch-PLGA) target lungs following their intravenous injection into mice. In this study we utilize an emulsification process and freeze drying to load the composite HAp/Ch-PLGA particles with 17β-hydroxy-17α-picolyl-androst-5-en-3β-yl-acetate (A), a chemotherapeutic derivative of androstane and a novel compound with a selective anticancer activity against lung cancer cells. 1 H NMR and 13 C NMR techniques confirmed the intact structure of the derivative A following its entrapment within HAp/Ch-PLGA particles. The thermogravimetric and differential thermal analyses coupled with mass spectrometry were used to assess the thermal degradation products and properties of A-loaded HAp/Ch-PLGA. The loading efficiency, as indicated by the comparison of enthalpies of phase transitions in pure A and A-loaded HAp/Ch-PLGA, equaled 7.47wt.%. The release of A from HAp/Ch-PLGA was sustained, neither exhibiting a burst release nor plateauing after three weeks. Atomic force microscopy and particle size distribution analyses were used to confirm that the particles were spherical with a uniform size distribution of d 50 =168nm. In vitro cytotoxicity testing of A-loaded HAp/Ch-PLGA using MTT and trypan blue dye exclusion assays demonstrated that the particles were cytotoxic to the A549 human lung carcinoma cell line (46±2%), while simultaneously preserving high viability (83±3%) of regular MRC5 human lung fibroblasts and causing no harm to primary mouse lung fibroblasts. In conclusion, composite A-loaded HAp/Ch-PLGA particles could be seen as promising drug delivery platforms for selective cancer therapies, targeting malignant cells for destruction, while having a significantly lesser cytotoxic effect on the healthy cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterisation of atmospheric deposited particles during a dust storm in urban areas of Eastern Australia.

PubMed

Gunawardena, Janaka; Ziyath, Abdul M; Bostrom, Thor E; Bekessy, Lambert K; Ayoko, Godwin A; Egodawatta, Prasanna; Goonetilleke, Ashantha

2013-09-01

The characteristics of dust particles deposited during the 2009 dust storm in the Gold Coast and Brisbane regions of Australia are discussed in this paper. The study outcomes provide important knowledge in relation to the potential impacts of dust storm related pollution on ecosystem health in the context that the frequency of dust storms is predicted to increase due to anthropogenic desert surface modifications and climate change impacts. The investigated dust storm contributed a large fraction of fine particles to the environment with an increased amount of total suspended solids, compared to dry deposition under ambient conditions. Although the dust storm passed over forested areas, the organic carbon content in the dust was relatively low. The primary metals present in the dust storm deposition were aluminium, iron and manganese, which are common soil minerals in Australia. The dust storm deposition did not contain significant loads of nickel, cadmium, copper and lead, which are commonly present in the urban environment. Furthermore, the comparison between the ambient and dust storm chromium and zinc loads suggested that these metals were contributed to the dust storm by local anthropogenic sources. The potential ecosystem health impacts of the 2009 dust storm include, increased fine solids deposition on ground surfaces resulting in an enhanced capacity to adsorb toxic pollutants as well as increased aluminium, iron and manganese loads. In contrast, the ecosystem health impacts related to organic carbon and other metals from dust storm atmospheric deposition are not considered to be significant. Copyright © 2013 Elsevier B.V. All rights reserved.

Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector.

PubMed

Mizuno, T; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Watanabe, K; Dairaku, M; Sakamoto, K; Inoue, T

2010-02-01

Heat load on acceleration grids by secondary particles such as electrons, neutrals, and positive ions, is a key issue for long pulse acceleration of negative ion beams. Complicated behaviors of the secondary particles in multiaperture, multigrid (MAMuG) accelerator have been analyzed using electrostatic accelerator Monte Carlo code. The analytical result is compared to experimental one obtained in a long pulse operation of a MeV accelerator, of which second acceleration grid (A2G) was removed for simplification of structure. The analytical results show that relatively high heat load on the third acceleration grid (A3G) since stripped electrons were deposited mainly on A3G. This heat load on the A3G can be suppressed by installing the A2G. Thus, capability of MAMuG accelerator is demonstrated for suppression of heat load due to secondary particles by the intermediate grids.

Loading an Optical Trap with Diamond Nanocrystals Containing Nitrogen-Vacancy Centers from a Surface

NASA Astrophysics Data System (ADS)

Hsu, Jen-Feng; Ji, Peng; Dutt, M. V. Gurudev; D'Urso, Brian R.

2015-03-01

We present a simple and effective method of loading particles into an optical trap. Our primary application of this method is loading photoluminescent material, such as diamond nanocrystals containing nitrogen-vacancy (NV) centers, for coupling the mechanical motion of the trapped crystal with the spin of the NV centers. Highly absorptive material at the trapping laser frequency, such as tartrazine dye, is used as media to attach nanodiamonds and burn into a cloud of air-borne particles as the material is swept near the trapping laser focus on a glass slide. Particles are then trapped with the laser used for burning or transferred to a second laser trap at a different wavelength. Evidence of successful loading diamond nanocrystals into the trap presented includes high sensitivity of the photoluminecscence (PL) to the excitation laser and the PL spectra of the optically trapped particles

ELM induced divertor heat loads on TCV

NASA Astrophysics Data System (ADS)

Marki, J.; Pitts, R. A.; Horacek, J.; Tskhakaya, D.; TCV Team

2009-06-01

Results are presented for heat loads at the TCV outer divertor target during ELMing H-mode using a fast IR camera. Benefitting from a recent surface cleaning of the entire first wall graphite armour, a comparison of the transient thermal response of freshly cleaned and untreated tile surfaces (coated with thick co-deposited layers) has been performed. The latter routinely exhibit temperature transients exceeding those of the clean ones by a factor ˜3, even if co-deposition throughout the first days of operation following the cleaning process leads to the steady regrowth of thin layers. Filaments are occasionally observed during the ELM heat flux rise phase, showing a spatial structure consistent with energy release at discrete toroidal locations in the outer midplane vicinity and with individual filaments carrying ˜1% of the total ELM energy. The temporal waveform of the ELM heat load is found to be in good agreement with the collisionless free streaming particle model.

Effects of gaseous sulphuric acid on diesel exhaust nanoparticle formation and characteristics.

PubMed

Rönkkö, Topi; Lähde, Tero; Heikkilä, Juha; Pirjola, Liisa; Bauschke, Ulrike; Arnold, Frank; Schlager, Hans; Rothe, Dieter; Yli-Ojanperä, Jaakko; Keskinen, Jorma

2013-10-15

Diesel exhaust gaseous sulphuric acid (GSA) concentrations and particle size distributions, concentrations, and volatility were studied at four driving conditions with a heavy duty diesel engine equipped with oxidative exhaust after-treatment. Low sulfur fuel and lubricant oil were used in the study. The concentration of the exhaust GSA was observed to vary depending on the engine driving history and load. The GSA affected the volatile particle fraction at high engine loads; higher GSA mole fraction was followed by an increase in volatile nucleation particle concentration and size as well as increase of size of particles possessing nonvolatile core. The GSA did not affect the number of nonvolatile particles. At low and medium loads, the exhaust GSA concentration was low and any GSA driven changes in particle population were not observed. Results show that during the exhaust cooling and dilution processes, besides critical in volatile nucleation particle formation, GSA can change the characteristics of all nucleation mode particles. Results show the dual nature of the nucleation mode particles so that the nucleation mode can include simultaneously volatile and nonvolatile particles, and fulfill the previous results for the nucleation mode formation, especially related to the role of GSA in formation processes.

Spontaneous formation of nanostructures inside inkjet-printed colloidal drops

NASA Astrophysics Data System (ADS)

Yang, Xin; Thorne, Nathaniel; Sun, Ying

2013-11-01

Nanostructures formed in inkjet-printed colloidal drops are systematically examined with different substrates and ink formulations. Various deposition patterns from multi-ring, radial spoke, firework to spider web, foam and island structures are observed. With a high particle loading, deposition transitions from multi-ring near the drop edge to spider web and finally to foam and islands in the center of the drop with 20 nm sulfate-modified polystyrene particles. At the same particle loading, 200 nm particles self-assemble into radial spokes at the drop edge and islands in the center, due to reduced contact line pinning resulted from less particles. In drops with a low particle concentration, due to fingering instability of the contact line, 20 nm particles form radial spokes enclosed by a ring, while 200 nm particles assemble into firework-like structures without a ring. Moreover, at a high particle loading, ruptures are observed on the multi-ring structure formed by 20 nm carboxylic-modified particles, due to stronger capillary forces from the contact line. Furthermore, for a drop printed on a less hydrophilic substrate, the interparticle interactions enable a more uniform deposition rather than complex nanostructures.

Ligand Assisted Stabilization of Fluorescence Nanoparticles; an Insight on the Fluorescence Characteristics, Dispersion Stability and DNA Loading Efficiency of Nanoparticles.

PubMed

Rhouati, Amina; Hayat, Akhtar; Mishra, Rupesh K; Bueno, Diana; Shahid, Shakir Ahmad; Muñoz, Roberto; Marty, Jean Louis

2016-07-01

This work reports on the ligand assisted stabilization of Fluospheres® carboxylate modified nanoparticles (FCMNPs), and subsequently investigation on the DNA loading capacity and fluorescence response of the modified particles. The designed fluorescence bioconjugate was characterized with enhanced fluorescence characteristics, good stability and large surface area with high DNA loading efficiency. For comparison purpose, bovine serum albumin (BSA) and polyethylene glycol (PEG) with three different length strands were used as cross linkers to modify the particles, and their DNA loading capacity and fluorescence characteristics were investigated. By comparing the performance of the particles, we found that the most improved fluorescence characteristics, enhanced DNA loading and high dispersion stability were obtained, when employing PEG of long spacer arm length. The designed fluorescence bioconjugate was observed to maintain all its characteristics under varying pH over an extended period of time. These types of bioconjugates are in great demand for fluorescence imaging and in vivo fluorescence biomedical application, especially when most of the as synthesized fluorescence particles cannot withstand to varying in vivo physiological conditions with decreases in fluorescence response and DNA loading efficiency.

Interannual variability of dust-mass loading and composition of dust deposited on snow cover in the San Juan Mountains, CO, USA: Insights into effects on snow melt

NASA Astrophysics Data System (ADS)

Goldstein, H. L.; Reynolds, R. L.; Derry, J.; Kokaly, R. F.; Moskowitz, B. M.

2017-12-01

Dust deposited on snow cover (DOS) in the American West can enhance snow-melt rates and advance the timing of melting, which together can result in earlier-than-normal runoff and overall smaller late-season water supplies. Understanding DOS properties and how they affect the absorption of solar radiation can lead to improved snow-melt models by accounting for important dust components. Here, we report on the interannual variability of DOS-mass loading, particle size, organic matter, and iron mineralogy, and their correspondences to laboratory-measured reflectance of samples from the Swamp Angel Study Plot in the San Juan Mountains, Colorado, USA. Samples were collected near the end of spring in water year 2009 (WY09) and from WY11-WY16, when dust layers deposited throughout the year had merged into one layer at the snow surface. Dust-mass loading on snow ranged 2-64 g/m2, mostly as particles with median sizes of 13-33 micrometers. Average reflectance values of DOS varied little across total (0.4 to 2.50 µm) and visible (0.4 to 0.7 µm) wavelengths at 0.30-0.45 and 0.19-0.27, respectively. Reflectance values lacked correspondence to particle-size. Total reflectance values inversely corresponded to concentrations of (1) organic matter content (4-20 weight %; r2 = 0.71) that included forms of black carbon and locally derived material such as pollen, and (2) magnetite (0.05 to 0.13 weight %; r2 = 0.44). Magnetite may be a surrogate for related dark, light-absorbing minerals. Concentrations of crystalline ferric oxide minerals (hematite+goethite) based on magnetic properties at room-temperature did not show inverse association to visible reflectance values. These ferric oxide measures, however, did not account for the amounts of nano-sized ferric oxides known to exist in these samples. Quantification of such nano-sized particles is required to evaluate their possible effects on visible reflectance. Nonetheless, our results emphasize that reflectance values of year-end DOS layers at this site do not appear to be highly sensitive to variations in some measured DOS properties. These preliminary results cannot be broadly applied to other DOS sites in the American West on the basis of previous and ongoing studies.

Divertor power and particle fluxes between and during type-I ELMs in the ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Kallenbach, A.; Dux, R.; Eich, T.; Fischer, R.; Giannone, L.; Harhausen, J.; Herrmann, A.; Müller, H. W.; Pautasso, G.; Wischmeier, M.; ASDEX Upgrade Team

2008-08-01

Particle, electric charge and power fluxes for type-I ELMy H-modes are measured in the divertor of the ASDEX Upgrade tokamak by triple Langmuir probes, shunts, infrared (IR) thermography and spectroscopy. The discharges are in the medium to high density range, resulting in predominantly convective edge localized modes (ELMs) with moderate fractional stored energy losses of 2% or below. Time resolved data over ELM cycles are obtained by coherent averaging of typically one hundred similar ELMs, spatial profiles from the flush-mounted Langmuir probes are obtained by strike point sweeps. The application of simple physics models is used to compare different diagnostics and to make consistency checks, e.g. the standard sheath model applied to the Langmuir probes yields power fluxes which are compared with the thermographic measurements. In between ELMs, Langmuir probe and thermography power loads appear consistent in the outer divertor, taking into account additional load due to radiation and charge exchange neutrals measured by thermography. The inner divertor is completely detached and no significant power flow by charged particles is measured. During ELMs, quite similar power flux profiles are found in the outer divertor by thermography and probes, albeit larger uncertainties in Langmuir probe evaluation during ELMs have to be taken into account. In the inner divertor, ELM power fluxes from thermography are a factor 10 larger than those derived from probes using the standard sheath model. This deviation is too large to be caused by deficiencies of probe analysis. The total ELM energy deposition from IR is about a factor 2 higher in the inner divertor compared with the outer divertor. Spectroscopic measurements suggest a quite moderate contribution of radiation to the target power load. Shunt measurements reveal a significant positive charge flow into the inner target during ELMs. The net number of elementary charges correlates well with the total core particle loss obtained from highly resolved density profiles. As a consequence, the discrepancy between probe and IR measurements is attributed to the ion power channel via a high mean impact energy of the ions at the inner target. The dominant contributing mechanism is proposed to be the directed loss of ions from the pedestal region into the inner divertor.

The effect of carbon black loading and structure on tensile property of natural rubber composite

NASA Astrophysics Data System (ADS)

Savetlana, S.; Zulhendri; Sukmana, I.; Saputra, F. A.

2017-07-01

Natural rubber composite has been continuously developed due to its advantages such as a good combination of strength and damping property. Most of carbon black (CB)/Natural Rubber (NR) composite were used as material in tyre industry. The addition of CB in natural rubber is very important to enhance the strength of natural rubber. The particle loading and different structure of CB can affect the composite strength. The effects of CB particle loading of 20, 25 and 30 wt% and the effects of CB structures of N220, N330, N550 and N660 series on tensile property of composite were investigated. The result shows that the tensile strength and elastic modulus of natural rubber/CB composite was higher than pure natural rubber. From SEM observation the agglomeration of CB aggregate increases with particle loading. It leads to decrease of tensile strength of composite as more particle was added. High structure of CB particle i.e. N220 resulted in highest tensile stress. In fact, composite reinforced by N660 CB particle shown a comparable tensile strength and elastic modulus with N220 CB particle. SEM observation shows that agglomeration of CB aggregates of N330 and N550 results in lower stress of associate NR/CB composite.

Universal characteristics of particle shape evolution by bed-load chipping

PubMed Central

Sipos, András Árpád; Shaw, Sam; Sarti, Giovanni; Domokos, Gábor

2018-01-01

River currents, wind, and waves drive bed-load transport, in which sediment particles collide with each other and Earth’s surface. A generic consequence is impact attrition and rounding of particles as a result of chipping, often referred to in geological literature as abrasion. Recent studies have shown that the rounding of river pebbles can be modeled as diffusion of surface curvature, indicating that geometric aspects of impact attrition are insensitive to details of collisions and material properties. We present data from fluvial, aeolian, and coastal environments and laboratory experiments that suggest a common relation between circularity and mass attrition for particles transported as bed load. Theory and simulations demonstrate that universal characteristics of shape evolution arise because of three constraints: (i) Initial particles are mildly elongated fragments, (ii) particles collide with similarly-sized particles or the bed, and (iii) collision energy is small enough that chipping dominates over fragmentation but large enough that sliding friction is negligible. We show that bed-load transport selects these constraints, providing the foundation to estimate a particle’s attrition rate from its shape alone in most sedimentary environments. These findings may be used to determine the contribution of attrition to downstream fining in rivers and deserts and to infer transport conditions using only images of sediment grains. PMID:29670937

Universal shape evolution of particles by bed-load

NASA Astrophysics Data System (ADS)

Jerolmack, D. J.; Domokos, G.; Shaw, S.; Sipos, A.; Szabo, T.

2016-12-01

River currents, wind and waves drive bed-load transport, in which sediment particles collide with each other and the Earth's surface. A generic consequence is erosion and rounding of particles as a result of chipping, often referred to in geological literature as abrasion. Recent studies have shown that the erosion of river pebbles can be modeled as diffusion of surface curvature, indicating that geometric aspects of chipping erosion are insensitive to details of collisions and material properties. Here we present data from fluvial, aeolian and coastal environments that suggest a universal relation between particle circularity and mass lost due to bed-load chipping. Simulations and experiments support the diffusion model and demonstrate that three constraints are required to produce this universal curve: (i) initial particles are fragments; (ii) erosion is dominated by collisions among like-sized particles; and (iii) collision energy is small enough that chipping dominates over fragmentation. We show that the mechanics of bedrock weathering and bed-load transport select these constraints, providing the foundation to estimate a particle's erosion rate from its shape alone in most sedimentary environments. These findings may be used to determine the contribution of chipping to downstream fining in rivers and deserts, and to infer transport conditions using only images of sediment grains.

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.

PubMed

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

2012-01-01

This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

Characterization of Potential Exposures to Nanoparticles and Fibers during Manufacturing and Recycling of Carbon Nanotube Reinforced Polypropylene Composites.

PubMed

Boonruksa, Pongsit; Bello, Dhimiter; Zhang, Jinde; Isaacs, Jacqueline A; Mead, Joey L; Woskie, Susan R

2016-01-01

Carbon nanotube (CNT) polymer composites are widely used as raw materials in multiple industries because of their excellent properties. This expansion, however, is accompanied by realistic concerns over potential release of CNTs and associated nanoparticles during the manufacturing, recycling, use, and disposal of CNT composite products. Such data continue to be limited, especially with regards to post-processing of CNT-enabled products, recycling and handling of nanowaste, and end-of-life disposal. This study investigated for the first time airborne nanoparticle and fibers exposures during injection molding and recycling of CNT polypropylene composites (CNT-PP) relative to that of PP. Exposure characterization focused on source emissions during loading, melting, molding, grinding, and recycling of scrap material over 20 cycles and included real-time characterization of total particle number concentration and size distribution, nanoparticle and fiber morphology, and fiber concentrations near the operator. Total airborne nanoparticle concentration emitted during loading, melting, molding, and grinding of CNT-PP had geometric mean ranging from 1.2 × 10(3) to 4.3 × 10(5) particles cm(-3), with the highest exposures being up to 2.9 and 300.7 times above the background for injection molding and grinding, respectively. Most of these emissions were similar to PP synthesis. Melting and molding of CNT-PP and PP produced exclusively nanoparticles. Grinding of CNT-PP but not PP generated larger particles with encapsulated CNTs, particles with CNT extrusions, and respirable fiber (up to 0.2 fibers cm(-3)). No free CNTs were found in any of the processes. The number of recycling runs had no significant impact on exposures. Further research into the chemical composition of the emitted nanoparticles is warranted. In the meanwhile, exposure controls should be instituted during processing and recycling of CNT-PP. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Gigavolt Bound free Transitions Driven by Extreme Light

DTIC Science & Technology

2016-05-12

negligible role in near term scenarios, but become interesting in the multi-exawatt regime. A significant advance in numerical particle tracking is... negligible , the total momentum distribution is f(p) = ∑ i |Srip| 2 (14) where i indexes each ion. By loading a large number of ions into any given simulation...spectrum of tunnel ionized electrons. RR is the force acting on an electron due to its own fields. This force is normally negligible , only becoming

Development of immobilized cellulase through functionalized gold nano-particles for glucose production by continuous hydrolysis of waste bamboo chopsticks.

PubMed

Cheng, Cheanyeh; Chang, Kuo-Chung

2013-12-10

Cellulase immobilized on silica through the assistance of l-cysteine functionalized gold nano-particle was applied for the continuous hydrolysis of waste bamboo chopsticks powder to produce glucose. The optimal conditions for the continuous hydrolysis were pH 8.0, 50°C. A 4-day reaction with an initial 0.3 gL⁻¹ waste bamboo chopsticks powder, a feed containing 0.2 gL⁻¹ waste bamboo chopsticks powder at a continuous feed and draw rate of 0.5 mLmin⁻¹, and an enzyme loading of 40 mgcellulase(gsilica)⁻¹, has 72.0-76.6% conversion rates of repeated hydrolyses that correspond to a total production of 630.5-671.2mg glucose and are much better than batch hydrolyses. At higher enzyme loading (117 mgcellulase(gsilica)⁻¹), higher initial concentration (0.5 gL⁻¹), and higher feed concentration (0.42 gL⁻¹) the conversion rate increases to 82.9% and a total amount of 1418 mgglucose. The immobilized cellulase can be recovered easily by filtration and used repeatedly at least 6 times over a period more than 90 days with a recovered activity approximately the same as or better than previous reactions. Thus the process is promising for scaling up. Copyright © 2013 Elsevier Inc. All rights reserved.

Absorption Study of Genistein Using Solid Lipid Microparticles and Nanoparticles: Control of Oral Bioavailability by Particle Sizes.

PubMed

Kim, Jeong Tae; Barua, Sonia; Kim, Hyeongmin; Hong, Seong-Chul; Yoo, Seung-Yup; Jeon, Hyojin; Cho, Yeongjin; Gil, Sangwon; Oh, Kyungsoo; Lee, Jaehwi

2017-07-01

In this study, the effect of particle size of genistein-loaded solid lipid particulate systems on drug dissolution behavior and oral bioavailability was investigated. Genistein-loaded solid lipid microparticles and nanoparticles were prepared with glyceryl palmitostearate. Except for the particle size, other properties of genistein-loaded solid lipid microparticles and nanoparticles such as particle composition and drug loading efficiency and amount were similarly controlled to mainly evaluate the effect of different particle sizes of the solid lipid particulate systems on drug dissolution behavior and oral bioavailability. The results showed that genistein-loaded solid lipid microparticles and nanoparticles exhibited a considerably increased drug dissolution rate compared to that of genistein bulk powder and suspension. The microparticles gradually released genistein as a function of time while the nanoparticles exhibited a biphasic drug release pattern, showing an initial burst drug release, followed by a sustained release. The oral bioavailability of genistein loaded in solid lipid microparticles and nanoparticles in rats was also significantly enhanced compared to that in bulk powders and the suspension. However, the bioavailability from the microparticles increased more than that from the nanoparticles mainly because the rapid drug dissolution rate and rapid absorption of genistein because of the large surface area of the genistein-solid lipid nanoparticles cleared the drug to a greater extent than the genistein-solid lipid microparticles did. Therefore, the findings of this study suggest that controlling the particle size of solid-lipid particulate systems at a micro-scale would be a promising strategy to increase the oral bioavailability of genistein.

Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

NASA Astrophysics Data System (ADS)

Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J.-F.

2012-12-01

We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea, Canadian Arctic Ocean, with a particular focus on free-living vs. particle-attached communities. Capillary electrophoresis-single strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between particle-attached (PA) and free-living (FL) bacterial communities in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (proxy of DOC and CDOM), suspended particles, amino acids and chlorophyll a. 16S rRNA genes pyrosequencing of selected samples confirmed these significant differences from river to sea and also between PA and FL fractions only in open sea samples, and PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, the coast and river samples, both PA and FL fractions, were dominated by Betaproteobacteria, Alphaproteobacteria and Actinobacteria. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a~basis to predict further changes in bacterial communities should climate change lead to further increases in river discharge and related particles load.

Balancing Conflicting Requirements for Grid and Particle Decomposition in Continuum-Lagrangian Solvers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitaraman, Hariswaran; Grout, Ray

2015-10-30

The load balancing strategies for hybrid solvers that involve grid based partial differential equation solution coupled with particle tracking are presented in this paper. A typical Message Passing Interface (MPI) based parallelization of grid based solves are done using a spatial domain decomposition while particle tracking is primarily done using either of the two techniques. One of the techniques is to distribute the particles to MPI ranks to whose grid they belong to while the other is to share the particles equally among all ranks, irrespective of their spatial location. The former technique provides spatial locality for field interpolation butmore » cannot assure load balance in terms of number of particles, which is achieved by the latter. The two techniques are compared for a case of particle tracking in a homogeneous isotropic turbulence box as well as a turbulent jet case. We performed a strong scaling study for more than 32,000 cores, which results in particle densities representative of anticipated exascale machines. The use of alternative implementations of MPI collectives and efficient load equalization strategies are studied to reduce data communication overheads.« less

Impact of nitrogen loading rates on treatment performance of domestic wastewater and fouling propensity in submerged membrane bioreactor (MBR).

PubMed

Khan, Sher Jamal; Ilyas, Shazia; Zohaib-Ur-Rehman

2013-08-01

In this study, performance of laboratory-scale membrane bioreactor (MBR) was evaluated in treating high strength domestic wastewater under two nitrogen loading rates (NLR) i.e., 0.15 and 0.30 kg/m(3)/d in condition 1 and 2, respectively, while organic loading rate (OLR) was constant at 3 kg/m(3)/d in both conditions. Removal efficiencies of COD were above 95.0% under both NLR conditions. Average removal efficiencies of ammonium nitrogen (NH₄(+)-N), total nitrogen (TN) and total phosphorus (TP) were found to be higher in condition 1 (90.5%, 74.0%, and 38.0%, respectively) as compared to that in Condition 2 (89.3%, 35.0%, and 14.0%, respectively). With increasing NLR, particle size distribution shifted from narrow (67-133 μm) towards broader distribution (3-300 μm) inferring lower cake layer porosity over membrane fibers. Soluble extracellular polymer substance (sEPS) concentration increased at higher NLR due to biopolymers released from broken flocs. Higher cake layer resistance (Rc) contributed towards shorter filtration runs during condition 2. Copyright © 2013 Elsevier Ltd. All rights reserved.

Seasonal microbial and environmental parameters at Crocker Reef, Florida Keys, 2014–2015

USGS Publications Warehouse

Kellogg, Christina A.; Yates, Kimberly K.; Lawler, Stephanie N.; Moore, Christopher S.; Smiley, Nathan A.

2015-11-04

Microbial measurements included enumeration of total bacteria, enumeration of virus-like particles, and plate counts of Vibrio spp. colony-forming units (CFU). These measurements were intended to give a sense of any seasonal changes in the total microbial load and to provide an indication of water quality. Additional environmental parameters measured included water temperature, salinity, dissolved oxygen, and pH. Four sites (table 1) were intensively sampled for periods of approximately 48 hours during summer (July 2014) and winter (January–February 2015), during which water samples were collected every 4 hours for analysis, except when prevented by weather conditions.

Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries

PubMed Central

David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

2016-01-01

Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm−2) delivers a charge capacity of ∼588 mAh g−1electrode (∼393 mAh cm−3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries. PMID:27025781

Characteristics of eugenol loaded chitosan-tripolyphosphate particles as affected by initial content of eugenol and their in-vitro release characteristic

NASA Astrophysics Data System (ADS)

Cahyono, B.; A’yun, Qurrotu; Suzery, M.; Hadiyanto

2018-04-01

The aim of this research was to determine encapsulation efficiency, loading capacity and controlled release of eugenol loaded chitosan-tpp products which prepared by coaservation method. The characteristic of eugenol-loaded chitosan showed that %EE and % LC increased by increasing the initial eugenol content. The optimum of %EE (72.63%) and %LC (43.96%) were obtained at the ratio of chitosan to eugenol of 1:1.5. The FTIR spectrum showed the characteristic peaks of eugenol appearing on spectrum of eugenol encapsulated and blue-shift in the hydroxyl band from 3425.58 cm-1 in chitosan-tpp to 3417.86 cm-1 and 3394.72 cm-1 in eugenol loaded chitosan-tpp indicating that eugenol was successfully encapsulated. The surface morphologies of freeze-dried particles with the optimum %EE showed that more surface roughness and porosity than plain particles. Furthermore, the in vitro release of particles with minimum and optimum %EE were also investigated in acid (Simulated Gastric Fluid) and base (Simulated Intestinal Fluid) medium at ambient temperature.

Hydrosilylated Porous Silicon Particles Function as an Intravitreal Drug Delivery System for Daunorubicin

PubMed Central

Hartmann, Kathrin I.; Nieto, Alejandra; Wu, Elizabeth C.; Freeman, William R.; Kim, Jae Suk; Chhablani, Jay; Sailor, Michael J.

2013-01-01

Abstract Purpose To evaluate in vivo ocular safety of an intravitreal hydrosilylated porous silicon (pSi) drug delivery system along with the payload of daunorubicin (DNR). Methods pSi microparticles were prepared from the electrochemical etching of highly doped, p-type Si wafers and an organic linker was attached to the Si-H terminated inner surface of the particles by thermal hydrosilylation of undecylenic acid. DNR was bound to the carboxy terminus of the linker as a drug-loading strategy. DNR release from hydrosilylated pSi particles was confirmed in the excised rabbit vitreous using liquid chromatography–electrospray ionization–multistage mass spectrometry. Both empty and DNR-loaded hydrosilylated pSi particles were injected into the rabbit vitreous and the degradation and safety were studied for 6 months. Results The mean pSi particle size was 30×46×15 μm with an average pore size of 15 nm. Drug loading was determined as 22 μg per 1 mg of pSi particles. An ex vivo drug release study showed that intact DNR was detected in the rabbit vitreous. An in vivo ocular toxicity study did not reveal clinical or pathological evidence of any toxicity during a 6-month observation. Hydrosilylated pSi particles, either empty or loaded with DNR, demonstrated a slow elimination kinetics from the rabbit vitreous without ocular toxicity. Conclusions Hydrosilylated pSi particles can host a large quantity of DNR by a covalent loading strategy and DNR can be slowly released into the vitreous without ocular toxicity, which would appear if an equivalent quantity of free drug was injected. PMID:23448595

Particle and gaseous emissions from compressed natural gas and ultralow sulphur diesel-fuelled buses at four steady engine loads.

PubMed

Jayaratne, E R; Ristovski, Z D; Meyer, N; Morawska, L

2009-04-01

Exhaust emissions from thirteen compressed natural gas (CNG) and nine ultralow sulphur diesel in-service transport buses were monitored on a chassis dynamometer. Measurements were carried out at idle and at three steady engine loads of 25%, 50% and 100% of maximum power at a fixed speed of 60 km h(-1). Emission factors were estimated for particle mass and number, carbon dioxide and oxides of nitrogen for two types of CNG buses (Scania and MAN, compatible with Euro 2 and 3 emission standards, respectively) and two types of diesel buses (Volvo Pre-Euro/Euro1 and Mercedez OC500 Euro3). All emission factors increased with load. The median particle mass emission factor for the CNG buses was less than 1% of that from the diesel buses at all loads. However, the particle number emission factors did not show a statistically significant difference between buses operating on the two types of fuel. In this paper, for the very first time, particle number emission factors are presented at four steady state engine loads for CNG buses. Median values ranged from the order of 10(12) particles min(-)(1) at idle to 10(15) particles km(-)(1) at full power. Most of the particles observed in the CNG emissions were in the nanoparticle size range and likely to be composed of volatile organic compounds The CO2 emission factors were about 20% to 30% greater for the diesel buses over the CNG buses, while the oxides of nitrogen emission factors did not show any difference due to the large variation between buses.

Modeling of Abrasion and Crushing of Unbound Granular Materials During Compaction

NASA Astrophysics Data System (ADS)

Ocampo, Manuel S.; Caicedo, Bernardo

2009-06-01

Unbound compacted granular materials are commonly used in engineering structures as layers in road pavements, railroad beds, highway embankments, and foundations. These structures are generally subjected to dynamic loading by construction operations, traffic and wheel loads. These repeated or cyclic loads cause abrasion and crushing of the granular materials. Abrasion changes a particle's shape, and crushing divides the particle into a mixture of many small particles of varying sizes. Particle breakage is important because the mechanical and hydraulic properties of these materials depend upon their grain size distribution. Therefore, it is important to evaluate the evolution of the grain size distribution of these materials. In this paper an analytical model for unbound granular materials is proposed in order to evaluate particle crushing of gravels and soils subjected to cyclic loads. The model is based on a Markov chain which describes the development of grading changes in the material as a function of stress levels. In the model proposed, each particle size is a state in the system, and the evolution of the material is the movement of particles from one state to another in n steps. Each step is a load cycle, and movement between states is possible with a transition probability. The crushing of particles depends on the mechanical properties of each grain and the packing density of the granular material. The transition probability was calculated using both the survival probability defined by Weibull and the compressible packing model developed by De Larrard. Material mechanical properties are considered using the Weibull probability theory. The size and shape of the grains, as well as the method of processing the packing density are considered using De Larrard's model. Results of the proposed analytical model show a good agreement with the experimental tests carried out using the gyratory compaction test.

Effluent sampling of Scout D and Delta launch vehicle exhausts

NASA Technical Reports Server (NTRS)

Hulten, W. C.; Storey, R. W.; Gregory, G. L.; Woods, D. C.; Harris, F. S., Jr.

1974-01-01

Characterization of engine-exhaust effluents (hydrogen chloride, aluminum oxide, carbon dioxide, and carbon monoxide) has been attempted by conducting field experiments monitoring the exhaust cloud from a Scout-Algol III vehicle launch and a Delta-Thor vehicle launch. The exhaust cloud particulate size number distribution (total number of particles as a function of particle diameter), mass loading, morphology, and elemental composition have been determined within limitations. The gaseous species in the exhaust cloud have been identified. In addition to the ground-based measurements, instrumented aircraft flights through the low-altitude, stabilized-exhaust cloud provided measurements which identified CO and HCI gases and Al2O3 particles. Measurements of the initial exhaust cloud during formation and downwind at several distances have established sampling techniques which will be used for experimental verification of model predictions of effluent dispersion and fallout from exhaust clouds.

Effect of particle momentum transfer on an oblique-shock-wave/laminar-boundary-layer interaction

NASA Astrophysics Data System (ADS)

Teh, E.-J.; Johansen, C. T.

2016-11-01

Numerical simulations of solid particles seeded into a supersonic flow containing an oblique shock wave reflection were performed. The momentum transfer mechanism between solid and gas phases in the shock-wave/boundary-layer interaction was studied by varying the particle size and mass loading. It was discovered that solid particles were capable of significant modulation of the flow field, including suppression of flow separation. The particle size controlled the rate of momentum transfer while the particle mass loading controlled the magnitude of momentum transfer. The seeding of micro- and nano-sized particles upstream of a supersonic/hypersonic air-breathing propulsion system is proposed as a flow control concept.

Dispersibility of lactose fines as compared to API in dry powders for inhalation.

PubMed

Thalberg, Kyrre; Åslund, Simon; Skogevall, Marcus; Andersson, Patrik

2016-05-17

This work investigates the dispersion performance of fine lactose particles as function of processing time, and compares it to the API, using Beclomethasone Dipropionate (BDP) as model API. The total load of fine particles is kept constant in the formulations while the proportions of API and lactose fines are varied. Fine particle assessment demonstrates that the lactose fines have higher dispersibility than the API. For standard formulations, processing time has a limited effect on the Fine Particle Fraction (FPF). For formulations containing magnesium stearate (MgSt), FPF of BDP is heavily influenced by processing time, with an initial increase, followed by a decrease at longer mixing times. An equation modeling the observed behavior is presented. Surprisingly, the dispersibility of the lactose fines present in the same formulation remains unaffected by mixing time. Magnesium analysis demonstrates that MgSt is transferred to the fine particles during the mixing process, thus lubrication both BDP and lactose fines, which leads to an increased FPF. Dry particle sizing of the formulations reveals a loss of fine particles at longer mixing times. Incorporation of fine particles into the carrier surfaces is believed to be behind this, and is hence a mechanism of importance as regards the dispersion performance of dry powders for inhalation. Copyright © 2016 Elsevier B.V. All rights reserved.

Dorzolamide Loaded Niosomal Vesicles: Comparison of Passive and Remote Loading Methods

PubMed Central

Hashemi Dehaghi, Mohadeseh; Haeri, Azadeh; Keshvari, Hamid; Abbasian, Zahra; Dadashzadeh, Simin

2017-01-01

Glaucoma is a common progressive eye disorder and the treatment strategies will benefit from nanoparticulate delivery systems with high drug loading and sustained delivery of intraocular pressure lowering agents. Niosomes have been reported as a novel approach to improve drug low corneal penetration and bioavailability characteristics. Along with this, poor entrapment efficiency of hydrophilic drug in niosomal formulation remains as a major formulation challenge. Taking this perspective into consideration, dorzolamide niosomes were prepared employing two different loading methodologies (passive and remote loading methods) and the effects of various formulation variables (lipid to drug ratio, cholesterol percentage, drug concentration, freeze/thaw cycles, TPGS content, and external and internal buffer molarity and pH) on encapsulation efficiency were assessed. Encapsulation of dorzolamide within niosomes increased remarkably by the incorporation of higher cholesterol percentage as well as increasing the total lipid concentration. Remote loading method showed higher efficacy for drug entrapment compared to passive loading technique. Incorporation of TPGS in bilayer led to decrease in EE; however, retarded drug release rate. Scanning electron microscopy (SEM) studies confirmed homogeneous particle distribution, and spherical shape with smooth surface. In conclusion, the highest encapsulation can be obtained using phosphate gradient method and 50% cholesterol in Span 60 niosomal formulation. PMID:28979296

Optical Trap Loading of Dielectric Microparticles In Air.

PubMed

Park, Haesung; LeBrun, Thomas W

2017-02-05

We demonstrate a method to trap a selected dielectric microparticle in air using radiation pressure from a single-beam gradient optical trap. Randomly scattered dielectric microparticles adhered to a glass substrate are momentarily detached using ultrasonic vibrations generated by a piezoelectric transducer (PZT). Then, the optical beam focused on a selected particle lifts it up to the optical trap while the vibrationally excited microparticles fall back to the substrate. A particle may be trapped at the nominal focus of the trapping beam or at a position above the focus (referred to here as the levitation position) where gravity provides the restoring force. After the measurement, the trapped particle can be placed at a desired position on the substrate in a controlled manner. In this protocol, an experimental procedure for selective optical trap loading in air is outlined. First, the experimental setup is briefly introduced. Second, the design and fabrication of a PZT holder and a sample enclosure are illustrated in detail. The optical trap loading of a selected microparticle is then demonstrated with step-by-step instructions including sample preparation, launching into the trap, and use of electrostatic force to excite particle motion in the trap and measure charge. Finally, we present recorded particle trajectories of Brownian and ballistic motions of a trapped microparticle in air. These trajectories can be used to measure stiffness or to verify optical alignment through time domain and frequency domain analysis. Selective trap loading enables optical tweezers to track a particle and its changes over repeated trap loadings in a reversible manner, thereby enabling studies of particle-surface interaction.

Characterization of a catalyst-based conversion technique to measure total particulate nitrogen and organic carbon and comparison to a particle mass measurement instrument

NASA Astrophysics Data System (ADS)

Stockwell, Chelsea E.; Kupc, Agnieszka; Witkowski, Bartłomiej; Talukdar, Ranajit K.; Liu, Yong; Selimovic, Vanessa; Zarzana, Kyle J.; Sekimoto, Kanako; Warneke, Carsten; Washenfelder, Rebecca A.; Yokelson, Robert J.; Middlebrook, Ann M.; Roberts, James M.

2018-05-01

The chemical composition of aerosol particles is a key aspect in determining their impact on the environment. For example, nitrogen-containing particles impact atmospheric chemistry, air quality, and ecological N deposition. Instruments that measure total reactive nitrogen (Nr = all nitrogen compounds except for N2 and N2O) focus on gas-phase nitrogen and very few studies directly discuss the instrument capacity to measure the mass of Nr-containing particles. Here, we investigate the mass quantification of particle-bound nitrogen using a custom Nr system that involves total conversion to nitric oxide (NO) across platinum and molybdenum catalysts followed by NO-O3 chemiluminescence detection. We evaluate the particle conversion of the Nr instrument by comparing to mass-derived concentrations of size-selected and counted ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), ammonium chloride (NH4Cl), sodium nitrate (NaNO3), and ammonium oxalate ((NH4)2C2O4) particles determined using instruments that measure particle number and size. These measurements demonstrate Nr-particle conversion across the Nr catalysts that is independent of particle size with 98 ± 10 % efficiency for 100-600 nm particle diameters. We also show efficient conversion of particle-phase organic carbon species to CO2 across the instrument's platinum catalyst followed by a nondispersive infrared (NDIR) CO2 detector. However, the application of this method to the atmosphere presents a challenge due to the small signal above background at high ambient levels of common gas-phase carbon compounds (e.g., CO2). We show the Nr system is an accurate particle mass measurement method and demonstrate its ability to calibrate particle mass measurement instrumentation using single-component, laboratory-generated, Nr-containing particles below 2.5 µm in size. In addition we show agreement with mass measurements of an independently calibrated online particle-into-liquid sampler directly coupled to the electrospray ionization source of a quadrupole mass spectrometer (PILS-ESI/MS) sampling in the negative-ion mode. We obtain excellent correlations (R2 = 0.99) of particle mass measured as Nr with PILS-ESI/MS measurements converted to the corresponding particle anion mass (e.g., nitrate, sulfate, and chloride). The Nr and PILS-ESI/MS are shown to agree to within ˜ 6 % for particle mass loadings of up to 120 µg m-3. Consideration of all the sources of error in the PILS-ESI/MS technique yields an overall uncertainty of ±20 % for these single-component particle streams. These results demonstrate the Nr system is a reliable direct particle mass measurement technique that differs from other particle instrument calibration techniques that rely on knowledge of particle size, shape, density, and refractive index.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hallerman, G.; Gray, R.J.

An instrument for crushing-strength determinations of uncoated and pyrolytic-carbon-coated fuel particles (50 to 500 mu in diameter) was developed to relate the crushing strength of the particles to their fabricability. The instrument consists of a loading mechanism, load cell, and a power supply-readout unit. The information that can be obtained by statistical methods of the data analysis is illustrated by results on two batches of fuel particles. (auth)

Synthesis, characterization and magnetic behavior of Co/MCM-41 nano-composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuello, N.; Elías, V.; CONICET

2013-09-15

Synthesis, structure and magnetic properties of Co/MCM-41 as magnetic nano-composites have been investigated. Mesoporous materials with different degrees of metal loading were prepared by wet impregnation and characterized by ICP, XRD, N{sub 2} adsorption, UV–vis DRS, TPR and EPMA-EDS. Cobalt oxide clusters and Co{sub 3}O{sub 4} nano-particles could be confined inside the mesopores of MCM-41, being this fact favored by the Co loading increasing. In addition, larger crystals of Co{sub 3}O{sub 4} detectable by XRD also grow on the surface when the Co loading is enhanced. The magnetic characterization was performed in a SQUID magnetometer using a maximum magnetic appliedmore » field µ{sub 0}Ha=1 T. While the samples with the higher Co loadings showed a behavior typically paramagnetic, a superparamagnetic contribution is more notorious for lower loadings, suggesting high Co species dispersion. - Graphical abstract: Room temperature hysteresis loops as a function of the Co content. Display Omitted - Highlights: • Co species as isolated Co{sup 2+}, oxide clusters and Co{sub 3}O{sub 4} nano-particles were detected. • For higher Co loads were detected, by XRD, Co{sub 3}O{sub 4} particles on the external surface. • The confining of Co species inside the mesopores was achieved by increasing Co load. • Paramagnetism from oxide clusters/nano-particles becomes dominant for higher Co loads. • Superparamagnetism can be assigned to Co species of small size and finely dispersed.« less

The Use of Clay-Polymer Nanocomposites in Wastewater Pretreatment

PubMed Central

Rytwo, Giora

2012-01-01

Some agricultural effluents are unsuitable for discharge into standard sewage-treatment plants: their pretreatment is necessary to avoid clogging of the filtering devices by colloidal matter. The colloidal stability of the effluents is mainly due to mutual repulsive forces that keep charged particles in suspension. Pretreatment processes are based on two separate stages: (a) neutralization of the charges (“coagulation”) and (b) bridging between several small particles to form larger aggregates that sink, leaving clarified effluent (“flocculation”). The consequent destabilization of the colloidal suspension lowers total suspended solids (TSSs), turbidity, and other environmental quality parameters, making the treatments that follow more efficient. Clay-based materials have been widely used for effluent pretreatment and pollutant removal. This study presents the use of nanocomposites, comprised of an anchoring particle and a polymer, as “coagoflocculants” for the efficient and rapid reduction of TSS and turbidity in wastewater with a high organic load. The use of such particles combines the advantages of coagulant and flocculant by neutralizing the charge of the suspended particles while bridging between them and anchoring them to a denser particle (the clay mineral), enhancing their precipitation. Very rapid and efficient pretreatment is achieved in one single treatment step. PMID:22454607

Formation of methotrexate-PLLA-PEG-PLLA composite microspheres by microencapsulation through a process of suspension-enhanced dispersion by supercritical CO2

PubMed Central

Chen, Ai-Zheng; Wang, Guang-Ya; Wang, Shi-Bin; Li, Li; Liu, Yuan-Gang; Zhao, Chen

2012-01-01

Background The aim of this study was to improve the drug loading, encapsulation efficiency, and sustained-release properties of supercritical CO2-based drug-loaded polymer carriers via a process of suspension-enhanced dispersion by supercritical CO2 (SpEDS), which is an advanced version of solution-enhanced dispersion by supercritical CO2 (SEDS). Methods Methotrexate nanoparticles were successfully microencapsulated into poly (L-lactide)-poly(ethylene glycol)-poly(L-lactide) (PLLA-PEG-PLLA) by SpEDS. Methotrexate nanoparticles were first prepared by SEDS, then suspended in PLLA-PEG-PLLA solution, and finally microencapsulated into PLLA-PEG-PLLA via SpEDS, where an “injector” was utilized in the suspension delivery system. Results After microencapsulation, the composite methotrexate (MTX)-PLLA-PEG-PLLA microspheres obtained had a mean particle size of 545 nm, drug loading of 13.7%, and an encapsulation efficiency of 39.2%. After an initial burst release, with around 65% of the total methotrexate being released in the first 3 hours, the MTX-PLLA-PEG-PLLA microspheres released methotrexate in a sustained manner, with 85% of the total methotrexate dose released within 23 hours and nearly 100% within 144 hours. Conclusion Compared with a parallel study of the coprecipitation process, microencapsulation using SpEDS offered greater potential to manufacture drug-loaded polymer microspheres for a drug delivery system. PMID:22787397

Preparation, characterization and stability of curcumin-loaded zein-shellac composite colloidal particles.

PubMed

Sun, Cuixia; Xu, Chenqi; Mao, Like; Wang, Di; Yang, Jie; Gao, Yanxiang

2017-08-01

Curcumin-loaded zein-shellac composite particles were prepared by the antisolvent co-precipitation method. The encapsulation efficiency of curcumin was significantly improved from 82.7% in zein particles to 93.2% in zein-shellac complex particles. The result of differential scanning calorimetry suggested that curcumin in the polymeric matrix was in an amorphous state. Fourier transform infrared spectroscopy analysis revealed that curcumin had non-covalently interacted with zein and shellac, mainly through hydrogen bonding and hydrophobic interaction. Aggregates in irregular shapes, with large sizes, were found by atomic force microscopy, and conglutination, integration or fusion of different entities into network structures occurred at a high level of shellac. At the mass ratio of zein to shellac of 1:1, curcumin in the complex particles exhibited improved photochemical and thermal stability. Curcumin-loaded zein-shellac complex particles allowed the controlled release of curcumin in both PBS medium and simulated gastrointestinal fluids. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterization of nanoparticulate MnS within the pores of mesoporous silica

NASA Astrophysics Data System (ADS)

Barry, Louse; Copley, Mark; Holmes, Justin D.; Otway, David J.; Kazakova, Olga; Morris, Michael A.

2007-12-01

Mesoporous silica was loaded with nanoparticulate MnS via a simple post-synthesis treatment. The mesoporous material that still contained surfactant was passivated to prevent MnS formation at the surface. The surfactant was extracted and a novel manganese ethylxanthate was used to impregnate the pore network. This precursor thermally decomposes to yield MnS particles that are smaller or equal to the pore size. The particles exhibit all three common polymorphs. The passivation treatment is most effective at lower loadings because at the highest loadings (SiO 2:MnS molar ratio of 6:1) large particles (>50 nm) form at the exterior of the mesoporous particles. The integrity of the mesoporous network is maintained through the preparation and high order is maintained. The MnS particles exhibit unexpected ferromagnetism at low temperatures. Strong luminescence of these samples is observed and this suggests that they may have a range of important application areas.

Determination of the emissions from an aircraft auxiliary power unit (APU) during the Alternative Aviation Fuel Experiment (AAFEX).

PubMed

Kinsey, John S; Timko, Michael T; Herndon, Scott C; Wood, Ezra C; Yu, Zhenhong; Miake-Lye, Richard C; Lobo, Prem; Whitefield, Philip; Hagen, Donald; Wey, Changlie; Anderson, Bruce E; Beyersdorf, Andreas J; Hudgins, Charles H; Thornhill, K Lee; Winstead, Edward; Howard, Robert; Bulzan, Dan I; Tacina, Kathleen B; Knighton, W Berk

2012-04-01

The emissions from a Garrett-AiResearch (now Honeywell) Model GTCP85-98CK auxiliary power unit (APU) were determined as part of the National Aeronautics and Space Administration's (NASA's) Alternative Aviation Fuel Experiment (AAFEX) using both JP-8 and a coal-derived Fischer Tropsch fuel (FT-2). Measurements were conducted by multiple research organizations for sulfur dioxide (SO2, total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), speciated gas-phase emissions, particulate matter (PM) mass and number, black carbon, and speciated PM. In addition, particle size distribution (PSD), number-based geometric mean particle diameter (GMD), and smoke number were also determined from the data collected. The results of the research showed PM mass emission indices (EIs) in the range of 20 to 700 mg/kg fuel and PM number EIs ranging from 0.5 x 10(15) to 5 x 10(15) particles/kg fuel depending on engine load and fuel type. In addition, significant reductions in both the SO2 and PM EIs were observed for the use of the FT fuel. These reductions were on the order of approximately 90% for SO2 and particle mass EIs and approximately 60% for the particle number EI, with similar decreases observed for black carbon. Also, the size of the particles generated by JP-8 combustion are noticeably larger than those emitted by the APU burning the FT fuel with the geometric mean diameters ranging from 20 to 50 nm depending on engine load and fuel type. Finally, both particle-bound sulfate and organics were reduced during FT-2 combustion. The PM sulfate was reduced by nearly 100% due to lack of sulfur in the fuel, with the PM organics reduced by a factor of approximately 5 as compared with JP-8.

Particle Communication and Domain Neighbor Coupling: Scalable Domain Decomposed Algorithms for Monte Carlo Particle Transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, M. J.; Brantley, P. S.

2015-01-20

In order to run Monte Carlo particle transport calculations on new supercomputers with hundreds of thousands or millions of processors, care must be taken to implement scalable algorithms. This means that the algorithms must continue to perform well as the processor count increases. In this paper, we examine the scalability of:(1) globally resolving the particle locations on the correct processor, (2) deciding that particle streaming communication has finished, and (3) efficiently coupling neighbor domains together with different replication levels. We have run domain decomposed Monte Carlo particle transport on up to 2 21 = 2,097,152 MPI processes on the IBMmore » BG/Q Sequoia supercomputer and observed scalable results that agree with our theoretical predictions. These calculations were carefully constructed to have the same amount of work on every processor, i.e. the calculation is already load balanced. We also examine load imbalanced calculations where each domain’s replication level is proportional to its particle workload. In this case we show how to efficiently couple together adjacent domains to maintain within workgroup load balance and minimize memory usage.« less

Lagrangian and Eulerian description of bed-load particle kinematics

NASA Astrophysics Data System (ADS)

Ballio, Francesco; Sadabadi, Seyed Abbas Hosseini; Pokrajac, Dubravka; Radice, Alessio

2016-04-01

The motion of bed-load sediment particles transported by a flow can be analyzed within a Lagrangian or an Eulerian framework. In the former case, we consider the particles as individual objects in motion and we study their kinematic properties. The latter approach is instead referred to suitably chosen control volumes. Quantities describing sediment motion in the two frameworks are different, and the relationships among the two approaches are not straightforward. In this work, we intend to discuss the kinematic properties of sediment transport: first, a set of quantities is univocally defined; then, relationships among different representations are explored. Proof-of-concept results presented in the study are from a recent experiment involving weak bed-load sediment transport, where the moving particles were released over a fixed rough bed. The bulk flow velocity was 1.4 times the critical value for incipient particle motion, and particles were mostly moving by rolling and sliding, with limited saltation. The particle motion was filmed from the top and the measurements were conducted by image-based methods, obtaining extensive samples of virtually-instantaneous quantities.

Intracellular trafficking of silicon particles and logic-embedded vectors

NASA Astrophysics Data System (ADS)

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-08-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments.Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. Electronic supplementary information (ESI) available: Confocal microscopy image showing internalized negative particles, and movie of the intracellular migration of silicon particles. See DOI: 10.1039/c0nr00227e

Quantification of the memory imprint effect for a charged particle environment

NASA Technical Reports Server (NTRS)

Bhuva, B. L.; Johnson, R. L., Jr.; Gyurcsik, R. S.; Kerns, S. E.; Fernald, K. W.

1987-01-01

The effects of total accumulated dose on the single-event vulnerability of NMOS resistive-load SRAMs are investigated. The bias-dependent shifts in device parameters can imprint the memory state present during exposure or erase the imprinted state. Analysis of these effects is presented along with an analytic model developed for the quantification of these effects. The results indicate that the imprint effect is dominated by the difference in the threshold voltage of the n-channel devices.

Microscopic anthropogenic litter in terrestrial birds from Shanghai, China: Not only plastics but also natural fibers.

PubMed

Zhao, Shiye; Zhu, Lixin; Li, Daoji

2016-04-15

The level of contamination by microscopic anthropogenic litter (0.5-5mm) in terrestrial ecosystems is not well understood. After chemical digestion in 10% KOH, microscopic anthropogenic litter from the gastrointestinal tracts of 17 terrestrial birds was identified and categorized under a stereomicroscope based on its physical properties and melting tests. In total, 364 items from 16 birds were identified as microscopic anthropogenic litter, ranging in size from 0.5 to 8.5mm. No relationship between plastic load and body condition was found. Natural fibers, plastic fibers and fragmented plastics represented, respectively, 37.4% (136 items), 54.9% (200 items) and 7.7% (28 items) of total litter items. Small sample sizes limited our ability to draw strong conclusions about the metabolism of natural fibers, but the decline in the proportion of natural fibers from the esophagus to stomach to intestine suggested that they may be digestible. Particles smaller than 5mm represented more than 90% of the total number of pollutant items. Particles with colors in the mid-tones and fibrous shapes were overwhelmingly common particles. The results reflect pollution by microscopic anthropogenic litter in the terrestrial ecosystem of the study area. Microscopic natural fibers, which may disperse and adsorb chemical pollutants differently from microplastic and may pose an even greater risk, are in urgent need of further research. Copyright © 2016 Elsevier B.V. All rights reserved.

3D Experimental Measurement of Lattice Strain and Fracture Behavior of Sand Particles Using Synchrotron X-Ray Diffraction and Tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cil, Mehmet B.; Alshibli, Khalid A.; Kenesei, Peter

3D synchrotron X-ray diffraction (3DXRD) and synchrotron micro-computed tomography (SMT) techniques were used to measure and monitor the lattice strain evolution and fracture behavior of natural Ottawa sand particles subjected to 1D compression loading. The particle-averaged lattice strain within sand particles was measured using 3DXRD and then was used to calculate the corresponding lattice stress tensor. In addition, the evolution and mode of fracture of sand particles was investigated using high-resolution 3D SMT images. The results of diffraction data analyses revealed that the major principal component of the lattice strain or stress tensor increased in most of the particles asmore » the global applied compressive load increased until the onset of fracture. Particle fracture and subsequent rearrangements caused significant variation and fluctuations in measured lattice strain/stress values from one particle to another and from one load step to the next one. SMT image analysis at the particle-scale showed that cracks in fractured sand particles generally initiate and propagate along the plane that connects the two contact points. Fractured particles initially split into two or three major fragments followed by disintegration into multiple smaller fragments in some cases. In conclusion, microscale analysis of fractured particles showed that particle position, morphology, the number and location of contact points play a major role in the occurrence of particle fracture in confined comminution of the sand assembly.« less

3D Experimental Measurement of Lattice Strain and Fracture Behavior of Sand Particles Using Synchrotron X-Ray Diffraction and Tomography

DOE PAGES

Cil, Mehmet B.; Alshibli, Khalid A.; Kenesei, Peter

2017-05-27

3D synchrotron X-ray diffraction (3DXRD) and synchrotron micro-computed tomography (SMT) techniques were used to measure and monitor the lattice strain evolution and fracture behavior of natural Ottawa sand particles subjected to 1D compression loading. The particle-averaged lattice strain within sand particles was measured using 3DXRD and then was used to calculate the corresponding lattice stress tensor. In addition, the evolution and mode of fracture of sand particles was investigated using high-resolution 3D SMT images. The results of diffraction data analyses revealed that the major principal component of the lattice strain or stress tensor increased in most of the particles asmore » the global applied compressive load increased until the onset of fracture. Particle fracture and subsequent rearrangements caused significant variation and fluctuations in measured lattice strain/stress values from one particle to another and from one load step to the next one. SMT image analysis at the particle-scale showed that cracks in fractured sand particles generally initiate and propagate along the plane that connects the two contact points. Fractured particles initially split into two or three major fragments followed by disintegration into multiple smaller fragments in some cases. In conclusion, microscale analysis of fractured particles showed that particle position, morphology, the number and location of contact points play a major role in the occurrence of particle fracture in confined comminution of the sand assembly.« less

Bond rupture between colloidal particles with a depletion interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whitaker, Kathryn A.; Furst, Eric M., E-mail: furst@udel.edu

The force required to break the bonds of a depletion gel is measured by dynamically loading pairs of colloidal particles suspended in a solution of a nonadsorbing polymer. Sterically stabilized poly(methyl methacrylate) colloids that are 2.7 μm diameter are brought into contact in a solvent mixture of cyclohexane-cyclohexyl bromide and polystyrene polymer depletant. The particle pairs are subject to a tensile load at a constant loading rate over many approach-retraction cycles. The stochastic nature of the thermal rupture events results in a distribution of bond rupture forces with an average magnitude and variance that increases with increasing depletant concentration. The measuredmore » force distribution is described by the flux of particle pairs sampling the energy barrier of the bond interaction potential based on the Asakura–Oosawa depletion model. A transition state model demonstrates the significance of lubrication hydrodynamic interactions and the effect of the applied loading rate on the rupture force of bonds in a depletion gel.« less

Single-pipetting microfluidic assay device for rapid detection of Salmonella from poultry package.

PubMed

Fronczek, Christopher F; You, David J; Yoon, Jeong-Yeol

2013-02-15

A direct, sensitive, near-real-time, handheld optical immunoassay device was developed to detect Salmonella typhimurium in the naturally occurring liquid from fresh poultry packages (hereafter "chicken matrix"), with just single pipetting of sample (i.e., no filtration, culturing and/or isolation, thus reducing the assay time and the error associated with them). Carboxylated, polystyrene microparticles were covalently conjugated with anti-Salmonella, and the immunoagglutination due to the presence of Salmonella was detected by reading the Mie scatter signals from the microfluidic channels using a handheld device. The presence of chicken matrix did not affect the light scatter signal, since the optical parameters (particle size d, wavelength of incident light λ and scatter angle θ) were optimized to minimize the effect of sample matrix (animal tissues and blood proteins, etc.). The sample was loaded into a microfluidic chip that was split into two channels, one pre-loaded with vacuum-dried, antibody-conjugated particles and the other with vacuum-dried, bovine serum albumin-conjugated particles. This eliminated the need for a separate negative control, effectively minimizing chip-to-chip and sample-to-sample variations. Particles and the sample were diffused in-channel through chemical agitation by Tween 80, also vacuum-dried within the microchannels. Sequential mixing of the sample to the reagents under a strict laminar flow condition synergistically improved the reproducibility and linearity of the assay. In addition, dried particles were shown to successfully detect lower Salmonella concentrations for up to 8 weeks. The handheld device contains simplified circuitry eliminating unnecessary adjustment stages, providing a stable signal, thus maximizing sensitivity. Total assay time was 10 min, and the detection limit 10 CFU mL(-1) was observed in all matrices, demonstrating the suitability of this device for field assays. Copyright © 2012 Elsevier B.V. All rights reserved.

Loading relativistic Maxwell distributions in particle simulations

NASA Astrophysics Data System (ADS)

Zenitani, Seiji

2015-04-01

Numerical algorithms to load relativistic Maxwell distributions in particle-in-cell (PIC) and Monte-Carlo simulations are presented. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are proposed in a physically transparent manner. Their acceptance efficiencies are ≈50 % for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

A poly(ethylene glycol)-based surfactant for formulation of drug-loaded mucus penetrating particles

PubMed Central

Mert, Olcay; Lai, Samuel K.; Ensign, Laura; Yang, Ming; Wang, Ying-Ying; Wood, Joseph; Hanes, Justin

2011-01-01

Mucosal surfaces are protected by a highly viscoelastic and adhesive mucus layer that traps most foreign particles, including conventional drug and gene carriers. Trapped particles are eliminated on the order of seconds to hours by mucus clearance mechanisms, precluding sustained and targeted drug and nucleic acid delivery to mucosal tissues. We have previously shown that polymeric coatings that minimize adhesive interactions with mucus constituents lead to particles that rapidly penetrate human mucus secretions. Nevertheless, a particular challenge in formulating drug-loaded mucus penetrating particles (MPP) is that many commonly used surfactants are either mucoadhesive, or do not facilitate efficient drug encapsulation. We tested a novel surfactant molecule for particle formulation composed of Vitamin E conjugated to 5 kDa polyethylene glycol (VP5k). We show that VP5k-coated poly(lactide-co-glycolide) (PLGA) nanoparticles rapidly penetrate human cervicovaginal mucus, whereas PLGA nanoparticles coated with polyvinyl alcohol or Vitamin E conjugated to 1 kDa PEG were trapped. Importantly, VP5k facilitated high loading of paclitaxel, a frontline chemo drug, into PLGA MPP, with controlled release for at least 4 days and negligible burst release. Our results offer a promising new method for engineering biodegradable, drug-loaded MPP for sustained and targeted delivery of therapeutics at mucosal surfaces. PMID:21911015

Influence of particulate trap oxidizers on emission of mutagenic compounds by diesel automobiles.

PubMed

Rasmussen, R E; Devillez, G; Smith, L R

1989-06-01

Diesel exhaust particles are known to contain mutagenic and carcinogenic chemicals. The aim of this study was to determine whether, and to what extent, catalytic particulate trap oxidizers on light-duty diesel engines may reduce the emission of particle-associated mutagenic chemicals into the environment. Exhaust particles were collected from Mercedes Benz and Volkswagen diesel automobiles, equipped with or without the manufacturer's exhaust traps, while running on a chassis dynamometer under specified load conditions. Exhaust particles were collected from a dilution tunnel onto 20" X 20" Teflon-coated fiberglass filters. Mutagenesis tests of dichloromethane (DCM) extracts of the particles were conducted using the Ames Salmonella bacterial test system. The mutation rate was calculated in terms of histidine revertants per mile of travel during a set of standard test cycles. With both vehicles the traps produced an 87-92% reduction in the total amount of particulate material collected by the filters. There was no significant change in the specific mutagenic activity (revertants per microgram of DCM particle extract) with or without the traps. These studies support the notion that installation of exhaust traps which reduce particulate emission on diesel-powered vehicles will also reduce the emission of particle-associated mutagenic and carcinogenic materials into the environment.

Children's Urinary Environmental Carbon Load. A Novel Marker Reflecting Residential Ambient Air Pollution Exposure?

PubMed

Saenen, Nelly D; Bové, Hannelore; Steuwe, Christian; Roeffaers, Maarten B J; Provost, Eline B; Lefebvre, Wouter; Vanpoucke, Charlotte; Ameloot, Marcel; Nawrot, Tim S

2017-10-01

Ambient air pollution, including black carbon, entails a serious public health risk because of its carcinogenic potential and as climate pollutant. To date, an internal exposure marker for black carbon particles that have cleared from the systemic circulation into the urine does not exist. To develop and validate a novel method to measure black carbon particles in a label-free way in urine. We detected urinary carbon load in 289 children (aged 9-12 yr) using white-light generation under femtosecond pulsed laser illumination. Children's residential black carbon concentrations were estimated based on a high-resolution spatial temporal interpolation method. We were able to detect urinary black carbon in all children, with an overall average (SD) of 98.2 × 10 5 (29.8 × 10 5 ) particles/ml. The urinary black carbon load was positively associated with medium-term to chronic (1 mo or more) residential black carbon exposure: +5.33 × 10 5 particles/ml higher carbon load (95% confidence interval, 1.56 × 10 5 to 9.10 × 10 5 particles/ml) for an interquartile range increment in annual residential black carbon exposure. Consistently, children who lived closer to a major road (≤160 m) had higher urinary black carbon load (6.93 × 10 5 particles/ml; 95% confidence interval, 0.77 × 10 5 to 13.1 × 10 5 ). Urinary black carbon mirrors the accumulation of medium-term to chronic exposure to combustion-related air pollution. This specific biomarker reflects internal systemic black carbon particles cleared from the circulation into the urine, allowing investigators to unravel the complexity of particulate-related health effects.

PLGA nano/microparticles loaded with cresyl violet as a tracer for drug delivery: Characterization and in-situ hyperspectral fluorescence and 2-photon localization.

PubMed

Lunardi, Claure N; Gomes, Anderson J; Palepu, Sandeep; Galwaduge, P Thilanka; Hillman, Elizabeth M C

2017-01-01

Here we present the production, characterization and in-vivo assessment of cresyl violet-loaded biodegradable PLGA nano/microparticles (CV-NP and CV-MP). We demonstrate that the beneficial spectral characteristics of cresyl violet make it suitable as a tracer for particle-based drug delivery using both hyperspectral wide field and two-photon excited fluorescence microscopy. Particles were prepared using a cosolvent method, after which the physicochemical properties such as morphology, particle size, drug entrapment efficiency, drug loading and in vitro drug release behavior were measured in addition to spectroscopic properties, such as absorption, fluorescence and infrared spectra. The particles were then tested in an in vivo mouse model to assess their biodistribution characteristics. The location and integrity of particles after injection was determined using both hyperspectral fluorescence and two-photon microscopy within intact organs in situ. Our results show that cresyl violet is efficiently entrapped into PLGA particles, and that the particles are spherical in shape, ranging from 300 to 5070nm in diameter. Particle biodistribution in the mouse was found to depend on particle size, as expected. Cresyl violet is shown to be an ideal tracer to assess the properties PLGA particle-based drug delivery in combination with our novel multi-scale optical imaging techniques for in-situ particle localization. Copyright © 2016 Elsevier B.V. All rights reserved.

EFFECTS ON ELECTROSTATIC PRECIPITATION OF CHANGES IN GRAIN LOADING, SIZE DISTRIBUTION, RESISTIVITY, AND TEMPERATURE

EPA Science Inventory

The paper discusses the simulation of the effects of changes to particle loading, particle size distribution, and electrostatic precipitator (ESP) operating temperatures using ESP models. It also illustrates the usefulness of modern ESP models for this type of analysis. Increasin...

How do gait frequency and serum-replacement interval affect polyethylene wear in knee-wear simulator tests?

PubMed

Reinders, Jörn; Sonntag, Robert; Kretzer, Jan Philippe

2014-11-01

Polyethylene wear (PE) is known to be a limiting factor in total joint replacements. However, a standardized wear test (e.g. ISO standard) can only replicate the complex in vivo loading condition in a simplified form. In this study, two different parameters were analyzed: (a) Bovine serum, as a substitute for synovial fluid, is typically replaced every 500,000 cycles. However, a continuous regeneration takes place in vivo. How does serum-replacement interval affect the wear rate of total knee replacements? (b) Patients with an artificial joint show reduced gait frequencies compared to standardized testing. What is the influence of a reduced frequency? Three knee wear tests were run: (a) reference test (ISO), (b) testing with a shortened lubricant replacement interval, (c) testing with reduced frequency. The wear behavior was determined based on gravimetric measurements and wear particle analysis. The results showed that the reduced test frequency only had a small effect on wear behavior. Testing with 1 Hz frequency is therefore a valid method for wear testing. However, testing with a shortened replacement interval nearly doubled the wear rate. Wear particle analysis revealed only small differences in wear particle size between the different tests. Wear particles were not linearly released within one replacement interval. The ISO standard should be revised to address the marked effects of lubricant replacement interval on wear rate.

Neuroprotective effect of curcumin-loaded lactoferrin nano particles against rotenone induced neurotoxicity.

PubMed

Bollimpelli, V Satish; Kumar, Prashant; Kumari, Sonali; Kondapi, Anand K

2016-05-01

Curcumin is known to have neuroprotective role and possess antioxidant, anti-inflammatory activities. Rotenone, a flavonoid induced neurotoxicity in dopaminergic cells is being widely studied in Parkinson's Disease (PD) research. In the present study, curcumin loaded lactoferrin nano particles prepared by sol-oil chemistry were used to protect dopaminergic cell line SK-N-SH against rotenone induced neurotoxicity. These curcumin loaded nano particles were of 43-60 nm diameter size and around 100 nm hydrodynamic size as assessed by transmission electron microscopy, atomic force microscopy and dynamic light scattering analysis respectively. The encapsulation efficiency was 61.3% ± 2.4%. Cellular uptake of curcumin through these nano particles was confirmed by confocal imaging and spectrofluorimetric analysis. The curcumin loaded lactoferrin nanoparticles showed greater intracellular drug uptake, sustained retention and greater neuroprotection than soluble counterpart. Neuroprotective activity was characterized through viability assays and by estimating ROS levels. Furthermore rotenone induced PD like features were characterized by decrease in tyrosine hydroxylase expression and increase in α-synuclein expression. Taken together curcumin loaded lactoferrin nanoparticles could be a promising drug delivery strategy against neurotoxicity in dopaminergic neurons. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improving understanding of mixed-land-use watershed suspended sediment regimes: Mechanistic progress through high-frequency sampling.

PubMed

Kellner, Elliott; Hubbart, Jason A

2017-11-15

Given the importance of suspended sediment to biogeochemical functioning of aquatic ecosystems, and the increasing concern of mixed-land-use effects on pollutant loading, there is an urgent need for research that quantitatively characterizes spatiotemporal variation of suspended sediment dynamics in contemporary watersheds. A study was conducted in a representative watershed of the central United States utilizing a nested-scale experimental watershed design, including five gauging sites (n=5) partitioning the catchment into five sub-watersheds. Hydroclimate stations at gauging sites were used to monitor air temperature, precipitation, and stream stage at 30-min intervals during the study (Oct. 2009-Feb. 2014). Streamwater grab samples were collected four times per week, at each site, for the duration of the study (Oct. 2009-Feb. 2014). Water samples were analyzed for suspended sediment using laser particle diffraction. Results showed significant differences (p<0.05) between monitoring sites for total suspended sediment concentration, mean particle size, and silt volume. Total concentration and silt volume showed a decreasing trend from the primarily agricultural upper watershed to the urban mid-watershed, and a subsequent increasing trend to the more suburban lower watershed. Conversely, mean particle size showed an opposite spatial trend. Results are explained by a combination of land use (e.g. urban stormwater dilution) and surficial geology (e.g. supply-controlled spatial variation of particle size). Correlation analyses indicated weak relationships with both hydroclimate and land use, indicating non-linear sediment dynamics. Suspended sediment parameters displayed consistent seasonality during the study, with total concentration decreasing through the growing season and mean particle size inversely tracking air temperature. Likely explanations include vegetation influences and climate-driven weathering cycles. Results reflect unique observations of spatiotemporal variation of suspended sediment particle size class. Such information is crucial for land and water resource managers working to mitigate aquatic ecosystem degradation and improve water resource sustainability in mixed-land-use watersheds globally. Copyright © 2017 Elsevier B.V. All rights reserved.

Fatigue Analyses Under Constant- and Variable-Amplitude Loading Using Small-Crack Theory

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Phillips, E. P.; Everett, R. A., Jr.

1999-01-01

Studies on the growth of small cracks have led to the observation that fatigue life of many engineering materials is primarily "crack growth" from micro-structural features, such as inclusion particles, voids, slip-bands or from manufacturing defects. This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using "small-crack theory" under various loading conditions. Constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective stress-intensity factor range (delta-Keff) under constant-amplitude loading. Modifications to the delta-Keff-rate relations in the near-threshold regime were needed to fit measured small-crack growth rate behavior. The model was then used to calculate small-and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens under constant-amplitude and spectrum loading. Fatigue lives were predicted using crack-growth relations and micro-structural features like those that initiated cracks in the fatigue specimens for most of the materials analyzed. Results from the tests and analyses agreed well.

Production of hybrid lipid-based particles loaded with inorganic nanoparticles and active compounds for prolonged topical release.

PubMed

García-González, C A; Sampaio da Sousa, A R; Argemí, A; López Periago, A; Saurina, J; Duarte, C M M; Domingo, C

2009-12-01

The production of particulate hybrid carriers containing a glyceryl monostearate (Lumulse GMS-K), a waxy triglyceride (Cutina HR), silanized TiO(2) and caffeine were investigated with the aim of producing sunscreens with UV-radiation protection properties. Particles were obtained using the supercritical PGSS (Particles from Gas Saturated Solutions) technique. This method takes advantages of the lower melting temperatures of the lipids obtained from the dissolution of CO(2) in the bulk mixture. Experiments were performed at 13 MPa and 345 K, according to previous melting point measurements. Blends containing Lumulse GMS-K and Cutina HR lipids (50 wt%) were loaded with silanized TiO(2) and caffeine in percentile proportions of 6 and 4 wt%, respectively. The particles produced were characterized using several analytical techniques as follows: system crystallinity was checked by X-ray diffraction and differential scanning calorimetry, thermal stability by thermogravimetric analysis, and morphology by scanning and transmission electron microscopy. Further, the UV-shielding ability of TiO(2) after its dispersion in the lipidic matrix was assessed by solid UV-vis spectroscopy. Preliminary results indicated that caffeine-loaded solid lipid particles presented a two-step dissolution profile, with an initial burst of 60 wt% of the loaded active agent. Lipid blends loaded with TiO(2) and caffeine encompassed the UV-filter behavior of TiO(2) and the photoaging prevention properties of caffeine.

Detailed characterization of particulate matter emitted by lean-burn gasoline direct injection engine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zelenyuk, Alla; Wilson, Jacqueline; Imre, Dan

This study presents detailed characterization of the chemical and physical properties of PM emitted by a 2.0L BMW lean-burn turbocharged GDI engine operated under a number of combustion strategies that include lean homogeneous, lean stratified, stoichiometric, and fuel rich conditions. We characterized PM number concentrations, size distributions, and the size, mass, compositions, and effective density of fractal and compact individual exhaust particles. For the fractal particles, these measurements yielded fractal dimension, average diameter of primary spherules, and number of spherules, void fraction, and dynamic shape factors as function of particle size. Overall, the PM properties were shown to vary significantlymore » with engine operation condition. Lean stratified operation yielded the most diesel-like size distribution and the largest PM number and mass concentrations, with nearly all particles being fractal agglomerates composed of elemental carbon with small amounts of ash and organics. In contrast, stoichiometric operation yielded a larger fraction of ash particles, especially at low speed and low load. Three distinct forms of ash particles were observed, with their fractions strongly dependent on engine operating conditions: sub-50 nm ash particles, abundant at low speed and low load, ash-containing fractal particles, and large compact ash particles that significantly contribute to PM mass loadings« less

[Preparation of curcumin-EC sustained-release composite particles by supercritical CO2 anti-solvent technology].

PubMed

Bai, Wei-li; Yan, Ting-yuan; Wang, Zhi-xiang; Huang, De-chun; Yan, Ting-xuan; Li, Ping

2015-01-01

Curcumin-ethyl-cellulose (EC) sustained-release composite particles were prepared by using supercritical CO2 anti-solvent technology. With drug loading and yield of inclusion complex as evaluation indexes, on the basis of single factor tests, orthogonal experimental design was used to optimize the preparation process of curcumin-EC sustained-release composite particles. The experiments such as drug loading, yield, particle size distribution, electron microscope analysis (SEM) , infrared spectrum (IR), differential scanning calorimetry (DSC) and in vitro dissolution were used to analyze the optimal process combination. The orthogonal experimental optimization process conditions were set as follows: crystallization temperature 45 degrees C, crystallization pressure 10 MPa, curcumin concentration 8 g x L(-1), solvent flow rate 0.9 mL x min(-1), and CO2 velocity 4 L x min(-1). Under the optimal conditions, the average drug loading and yield of curcumin-EC sustained-release composite particles were 33.01% and 83.97%, and the average particle size of the particles was 20.632 μm. IR and DSC analysis showed that curcumin might complex with EC. The experiments of in vitro dissolution showed that curcumin-EC composite particles had good sustained-release effect. Curcumin-EC sustained-release composite particles can be prepared by supercritical CO2 anti-solvent technology.

Characterization of domestic graywater and graywater solids.

PubMed

Sievers, Jan Christian; Londong, Jörg

2018-03-01

The knowledge of loads and concentrations is fundamental for the design of graywater treatment units, but the data on the characteristics of graywater and in particular graywater solids are weak. As general design values regarding graywater treatment facilities are not available for Germany, the objective of this article is to elaborate the characteristics of graywater and graywater solids. This paper describes the results of six sampling campaigns carried out on graywater systems in the German cities Berlin, Lübeck and Kiel. All graywater samples were collected proportional to the flow and the graywater solids were gathered separately. The collected data include graywater volumes and characteristics regarding the organic pollution (chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD 5 )) and nutrients (total nitrogen (TN), total phosphorus (TP)). The graywater volume fluctuated depending on the location. The specific average flow was 68 litre per inhabitant per day (L/inh.d). Inhabitant-specific loads of 49.3 gCOD t /inh·d, 28 gBOD 5 /inh.d, 1 gTN t /inh.d and 0.38 gTP t /inh.d (subscript 't' = total) were found. Information about the composition of graywater solids in terms of quantity and quality is seriously lacking. Therefore, graywater solids were examined with respect to organic matter (COD) and nutrients (TN, TP). The contribution of graywater solids with particle sizes over 200 microns in relation to the total inhabitant-specific load was approximately 3-8% depending on the parameter. The qualitative and quantitative characteristics of the investigated graywater fractions may serve as a base for the estimation of design values.

Design, characterization, and in vitro cellular inhibition and uptake of optimized genistein-loaded NLC for the prevention of posterior capsular opacification using response surface methodology.

PubMed

Zhang, Wenji; Li, Xuedong; Ye, Tiantian; Chen, Fen; Sun, Xiao; Kong, Jun; Yang, Xinggang; Pan, Weisan; Li, Sanming

2013-09-15

This study was to design an innovative nanostructured lipid carrier (NLC) for drug delivery of genistein applied after cataract surgery for the prevention of posterior capsular opacification. NLC loaded with genistein (GEN-NLC) was produced with Compritol 888 ATO, Gelucire 44/14 and Miglyol 812N, stabilized by Solutol(®) HS15 by melt emulsification method. A 2(4) central composite design of 4 independent variables was performed for optimization. Effects of drug concentration, Gelucire 44/14 concentration in total solid lipid, liquid lipid concentration, and surfactant concentration on the mean particle size, polydispersity index, zeta potential and encapsulation efficiency were investigated. Analysis of variance (ANOVA) statistical test was used to assess the optimization. The optimized GEN-NLC showed a homogeneous particle size of 90.16 nm (with PI=0.33) of negatively charged surface (-25.08 mv) and high encapsulation efficiency (91.14%). Particle morphology assessed by TEM revealed a spherical shape. DSC analyses confirmed that GEN was mostly entrapped in amorphous state. In vitro release experiments indicated a prolonged and controlled genistein release for 72 h. In vitro growth inhibition assay showed an effective growth inhibition of GEN-NLCs on human lens epithelial cells (HLECs). Preliminary cellular uptake test proved a enhanced penetration of genistein into HLECs when delivered in NLC. Copyright © 2013 Elsevier B.V. All rights reserved.

Impact of mash feeding versus pellets on propionic/butyric acid levels and on total load in the gastrointestinal tract of growing pigs.

PubMed

Longpré, J; Fairbrother, J M; Fravalo, P; Arsenault, J; LeBel, P; Laplante, B; Surprenant, C; Massé, D; Letellier, A

2016-03-01

Feed characteristics may influence the bacterial community composition and metabolic activities in the pig gastrointestinal tract, known to be associated with positive effects on the gut. Use of mash feed is associated with reduced excretion, but little is known of its effect on the population or of the mechanism of action. Our objectives were to assess the effect of feed texture combined with feed particle size on VFA profiles and levels, total count, and the presence of genes encoding virulence factors of pathogenic strains in the digestive tract along with their impact on pig performance of fattening pigs. Pigs ( = 840) on a commercial farm received mash or pellet diets of different particle sizes during the fattening period. Caecal and colon contents from 164 pigs were sampled at the slaughterhouse for enumeration of by quantitative PCR (qPCR) and for VFA quantification by capillary gas chromatography. The gene was used to enumerate total . Improved pig performances associated with pellet texture and a 500-μm size were observed. Caecal ( = 0.02) and colon ( < 0.01) propionic acid concentrations were lower for pigs receiving pellet rather than mash feed. Similarly, caecal ( = 0.01) and colon ( < 0.001) butyric acid concentrations were also lower for pigs receiving pellet rather than mash feed, as determined by capillary gas chromatography. Moreover, caecal ( = 0.03) and colon ( < 0.001) butyric acid concentrations were higher for pigs receiving a feed with a 1,250-μm particle size rather than a 500-μm particle size. On the other hand, total caecal and colon levels were higher for pigs receiving pellet feed than for those receiving mash feed. For total enumeration, caecal ( < 0.01) and colon ( < 0.01) gene copies were higher for pigs receiving pellet rather than mash feed. No effect of particle size on fatty acid concentrations or on numbers was observed. Virulence gene quantification revealed no trend. Taken together, results showed that mash feed is associated with lower growth performance but with favorable intestinal changes linked to VFA levels and reduction in the intestine.

Competition of coagulation sink and source rate: New particle formation in the Pearl River Delta of China

NASA Astrophysics Data System (ADS)

Gong, Youguo; Hu, Min; Cheng, Yafang; Su, Hang; Yue, Dingli; Liu, Feng; Wiedensohler, A.; Wang, Zhibin; Kalesse, H.; Liu, Shang; Wu, Zhijun; Xiao, Kaitao; Mi, Puchun; Zhang, Yuanhang

The coagulation sink and its role in new particle formation are investigated based on data obtained during the PRIDE-PRD2004 campaign at Xinken of Pearl River Delta, China. Analysis of size distributions and mode contributions of the coagulation sink show that the observed higher load of accumulation mode particles impose a significant effect on the coagulation sink and result in higher coagulation sinks at Xinken despite of the lower total particle number compared with other areas. Hence it is concluded that the higher coagulation sink may depress the occurrence frequency of new particle formation events. The strategies targeting at controlling accumulation mode particles may have influences on the frequency of new particle formation events at this area. The factors affecting the coagulation sink are evaluated. The relatively lower ambient relative humidities may weaken the coagulation sink and facilitate the occurrence of new particle formation events during noontime, while the surmise of nucleation and growth involving organic matter may imply an actually higher coagulation sink than expected. These factors have a significant influence on the ultimate fate of the newly formed nuclei and new particle formation. A comparison of event and non-event days indicates that the coagulation sink is not the only decisive factor affecting new particle formation, other factors including the precursor vapors and photochemical activity are none the less important either. Competition of coagulation sink and high source rate leads to the occurrence of new particle formation events at Xinken.

Thiolated chitosan nanoparticles as a delivery system for antisense therapy: evaluation against EGFR in T47D breast cancer cells

PubMed Central

Talaei, Fatemeh; Azizi, Ebrahim; Dinarvand, Rassoul; Atyabi, Fatemeh

2011-01-01

Thiolated chitosan has high transfection and mucoadhesive properties. We investigated the potential of two recently synthesized polymers: NAC-C (N-acetyl cysteine-chitosan) and NAP-C (N-acetyl penicillamine-chitosan) in anticancer drug delivery targeting epidermal growth factor receptor (EGFR). Doxorubicin (DOX) and antisense oligonucleotide (ASOND)-loaded polymer nanoparticles were prepared in water by a gelation process. Particle characterization, drug loading, and drug release were evaluated. To verify drug delivery efficiency in vitro experiments on a breast cancer cell line (T47D) were performed. EGFR gene and protein expression was analyzed by real time quantitative polymerase chain reaction and Western blotting, respectively. A loading percentage of 63% ± 5% for ASOND and 70% ± 5% for DOX was achieved. Drug release data after 15 hours showed that ASOND and DOX were completely released from chitosan-based particles while a lower and more sustained release of only 22% ± 8% was measured for thiolated particles. In a cytosol simulated release medium/reducing environment, such as found intracellularly, polymer-based nanoparticles dissociated, liberating approximately 50% of both active substances within 7 hours. ASOND-loaded polymer nanoparticles had higher stability and high mucoadhesive properties. The ASOND-loaded thiolated particles significantly suppressed EGFR gene expression in T47D cells compared with ASOND-loaded chitosan particles and downregulated EGFR protein expression in cells. This study could facilitate future investigations into the functionality of NAP-C and NAC-C polymers as an efficient ASOND delivery system in vitro and in vivo. PMID:21976973

Thiolated chitosan nanoparticles as a delivery system for antisense therapy: evaluation against EGFR in T47D breast cancer cells.

PubMed

Talaei, Fatemeh; Azizi, Ebrahim; Dinarvand, Rassoul; Atyabi, Fatemeh

2011-01-01

Thiolated chitosan has high transfection and mucoadhesive properties. We investigated the potential of two recently synthesized polymers: NAC-C (N-acetyl cysteine-chitosan) and NAP-C (N-acetyl penicillamine-chitosan) in anticancer drug delivery targeting epidermal growth factor receptor (EGFR). Doxorubicin (DOX) and antisense oligonucleotide (ASOND)-loaded polymer nanoparticles were prepared in water by a gelation process. Particle characterization, drug loading, and drug release were evaluated. To verify drug delivery efficiency in vitro experiments on a breast cancer cell line (T47D) were performed. EGFR gene and protein expression was analyzed by real time quantitative polymerase chain reaction and Western blotting, respectively. A loading percentage of 63% ± 5% for ASOND and 70% ± 5% for DOX was achieved. Drug release data after 15 hours showed that ASOND and DOX were completely released from chitosan-based particles while a lower and more sustained release of only 22% ± 8% was measured for thiolated particles. In a cytosol simulated release medium/reducing environment, such as found intracellularly, polymer-based nanoparticles dissociated, liberating approximately 50% of both active substances within 7 hours. ASOND-loaded polymer nanoparticles had higher stability and high mucoadhesive properties. The ASOND-loaded thiolated particles significantly suppressed EGFR gene expression in T47D cells compared with ASOND-loaded chitosan particles and downregulated EGFR protein expression in cells. This study could facilitate future investigations into the functionality of NAP-C and NAC-C polymers as an efficient ASOND delivery system in vitro and in vivo.

Determination of hand soil loading, soil transfer, and particle size variations after hand-pressing and hand-mouthing activities

EPA Science Inventory

Hand-pressing trials and hand-to-mouth soil transfer experiments were conducted to better understand soil loadings, soil transfer ratios for three mouthing activities, and variations in particle size distributions under various conditions. Results indicated that sand caused highe...

Formulation optimization of aprepitant microemulsion-loaded silicated corn fiber gum particles for enhanced bioavailability.

PubMed

Kamboj, Sunil; Rana, Vikas

2016-08-01

The present investigation was aimed at development of silicate corn fiber gum (SCFG) particles as superior solid carrier for the preparation of Aprepitant (APT)-loaded self-emulsifying powder (SEP) system. 2(4) D-optimal mixture design with three level process variables was employed to develop SCFG particles, utilizing flow descriptors and hydrophobicity descriptors as response variables. The results indicated that blending of CFG (51.4% w/w) and magnesium silicate (MS) (48.6% w/w) using freeze-drying technique was found to have highest desirability (0.904). The developed SEP showed highest oil desorbing capacity, low self-emulsification time and highest drug content. It was observed that SCFG-SEP (F2 formulation) showed lowest PDI (0.2445 ± 0.03) as well as smallest particle size (127 ± 5.8 nm). The droplets were uniform and maintain their integrity after reconstitution (TEM analysis). Furthermore, APT-loaded SEP showed enhanced in vitro dissolution (4 folds) and ex vivo performance (7-fold enhanced Papp) as compared to pure APT. Furthermore, in vivo pharmacokinetic study showed that significant enhancement (p > 0.05) in Cmax was evident with APT-loaded F2 (SCFG-SEP) (1.93-fold) and F4 (Aerosil 200-SEP) (1.58-fold). The data also suggested increase in absorption rate when APT incorporated into SCFG-SEP. Thus, findings pointed toward enhanced bioavailability of APT when loaded into SCFG particles. Overall, the developed SCFG particles could be considered as a better alternative to already available solid carrier(s).

Intracellular Trafficking of Silicon Particles and Logic-Embedded Vectors

PubMed Central

Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

2010-01-01

Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments. PMID:20820744

Effect of drug load and plate coating on the particle size distribution of a commercial albuterol metered dose inhaler (MDI) determined using the Andersen and Marple-Miller cascade impactors.

PubMed

Nasr, M M; Ross, D L; Miller, N C

1997-10-01

The purpose of this study is to investigate the effect of drug load, the coating of impactor stages, and the design of cascade impactors on albuterol MDIs particle size distribution measurements. The results of the investigation will be used to explain the "loading effect" recently reported. Particle size distribution parameters of a commercial albuterol MDI were measured using both Andersen (AI) and Marple-Miller (MMI) Cascade Impactors, where plates were either left uncoated or coated with silicone or glycerin. A previously validated HPLC-EC method was used for the assay of albuterol collected by the impactor and in single spray content determinations. Coating impactor collection plates had an impact on measured MMAD and GSD values for single puff measurements but very little or no effect for the multi puff measurements. Due to particle bounce, the percent of albuterol fine particles deposited in the filter and impactor finer stages (< 1.10 microns in AI and < 1.25 microns in MMI) in uncoated single puff experiments was much higher in comparison to either coated single puff or multi-puff (coated and uncoated) measurements. Evaluation of drug load and plate coating are necessary to determine whether observed particle size distributions are representative of the generated aerosol or are the result of particle bounce and reentrainment. In order to minimize particle bounce, especially for single puff determinations, it may be useful to apply a thin layer of a sticky coating agent to the surfaces of impactor plates.

Fermentation of sugarcane bagasse and chicken manure to calcium carboxylates under thermophilic conditions.

PubMed

Fu, Zhihong; Holtzapple, Mark T

2010-09-01

Sugarcane bagasse and chicken manure were anaerobically fermented to carboxylic acids using a mixed culture of marine microorganisms at 55 degrees C. Using the MixAlco process--an example of consolidated bioprocessing--the resulting carboxylate salts can be converted to mixed alcohol fuels or gasoline. To enhance digestibility, sugarcane bagasse was lime pretreated with 0.1 g Ca(OH)(2)/g dry biomass at 100 degrees C for 2 h. Four-stage countercurrent fermentation of 80% sugarcane bagasse/20% chicken manure was performed at various volatile solids (VS) loading rates and liquid residence times. Calcium carbonate was used as a buffer during fermentation. The highest acid productivity of 0.79 g/(L day) occurred at a total acid concentration of 21.5 g/L. The highest conversion (0.59 g VS digested/g VS fed) and yield (0.18 g total acids/g VS fed) occurred at a total acid concentration of 15.5 g/L. The continuum particle distribution model (CPDM) predicted the experimental total acid concentrations and conversions at an average error of 10.14% and 12.68%, respectively. CPDM optimizations show that high conversion (>80%) and total acid concentration of 21.3 g/L are possible with 300 g substrate/(L liquid), 30 days liquid residence time, and 3 g/(L day) solid loading rate. Thermophilic fermentation has a higher acetate content (approximately 63 wt%) than mesophilic fermentation (approximately 39 wt%).

Diffusion rate limitations in actin-based propulsion of hard and deformable particles.

PubMed

Dickinson, Richard B; Purich, Daniel L

2006-08-15

The mechanism by which actin polymerization propels intracellular vesicles and invasive microorganisms remains an open question. Several recent quantitative studies have examined propulsion of biomimetic particles such as polystyrene microspheres, phospholipid vesicles, and oil droplets. In addition to allowing quantitative measurement of parameters such as the dependence of particle speed on its size, these systems have also revealed characteristic behaviors such a saltatory motion of hard particles and oscillatory deformation of soft particles. Such measurements and observations provide tests for proposed mechanisms of actin-based motility. In the actoclampin filament end-tracking motor model, particle-surface-bound filament end-tracking proteins are involved in load-insensitive processive insertion of actin subunits onto elongating filament plus-ends that are persistently tethered to the surface. In contrast, the tethered-ratchet model assumes working filaments are untethered and the free-ended filaments grow as thermal ratchets in a load-sensitive manner. This article presents a model for the diffusion and consumption of actin monomers during actin-based particle propulsion to predict the monomer concentration field around motile particles. The results suggest that the various behaviors of biomimetic particles, including dynamic saltatory motion of hard particles and oscillatory vesicle deformations, can be quantitatively and self-consistently explained by load-insensitive, diffusion-limited elongation of (+)-end-tethered actin filaments, consistent with predictions of the actoclampin filament-end tracking mechanism.

The photoelectronic behaviors of MoO3-loaded ZrO2/carbon cluster nanocomposite materials

NASA Astrophysics Data System (ADS)

Matsui, H.; Ishiko, A.; Karuppuchamy, S.; Hassan, M. A.; Yoshihara, M.

2012-03-01

A novel nano-sized ZrO2/carbon cluster composite materials (Ic's) were successfully obtained by the calcination of ZrCl4/starch complexes I's under an argon atmosphere. Pt- and/or MoO3-loaded ZrO2/carbon clusters composite materials were also prepared by doping Pt and/or MoO3 particles on the surface of Ic's. The surface characterization of the composite materials was carried out using transmission electron microscopy (TEM). The TEM observation of the materials showed the presence of particles with the diameters of a few nanometers, possibly Pt particles, and of 50-100 nm, possibly MoO3 particles, in the matrix. Pt- and/or MoO3-loaded ZrO2/carbon cluster composite materials show the efficient photocatalytic activity under visible light irradiation.

Experimental studies of the effects of buffered particle dampers attached to a multi-degree-of-freedom system under dynamic loads

NASA Astrophysics Data System (ADS)

Lu, Zheng; Lu, Xilin; Lu, Wensheng; Masri, Sami F.

2012-04-01

This paper presents a systematic experimental investigation of the effects of buffered particle dampers attached to a multi-degree-of-freedom (mdof) system under different dynamic loads (free vibration, random excitation as well as real onsite earthquake excitations), and analytical/computational study of such a system. A series of shaking table tests of a three-storey steel frame with the buffered particle damper system are carried out to evaluate the performance and to verify the analysis method. It is shown that buffered particle dampers have good performance in reducing the response of structures under dynamic loads, especially under random excitation case. It can effectively control the fundamental mode of the mdof primary system; however, the control effect for higher modes is variable. It is also shown that, for a specific container geometry, a certain mass ratio leads to more efficient momentum transfer from the primary system to the particles with a better vibration attenuation effect, and that buffered particle dampers have better control effect than the conventional rigid ones. An analytical solution based on the discrete element method is also presented. Comparison between the experimental and computational results shows that reasonably accurate estimates of the response of a primary system can be obtained. Properly designed buffered particle dampers can effectively reduce the response of lightly damped mdof primary system with a small weight penalty, under different dynamic loads.

Effect of fuel injection pressure on a heavy-duty diesel engine nonvolatile particle emission.

PubMed

Lähde, Tero; Rönkkö, Topi; Happonen, Matti; Söderström, Christer; Virtanen, Annele; Solla, Anu; Kytö, Matti; Rothe, Dieter; Keskinen, Jorma

2011-03-15

The effects of the fuel injection pressure on a heavy-duty diesel engine exhaust particle emissions were studied. Nonvolatile particle size distributions and gaseous emissions were measured at steady-state engine conditions while the fuel injection pressure was changed. An increase in the injection pressure resulted in an increase in the nonvolatile nucleation mode (core) emission at medium and at high loads. At low loads, the core was not detected. Simultaneously, a decrease in soot mode number concentration and size and an increase in the soot mode distribution width were detected at all loads. Interestingly, the emission of the core was independent of the soot mode concentration at load conditions below 50%. Depending on engine load conditions, growth of the geometric mean diameter of the core mode was also detected with increasing injection pressure. The core mode emission and also the size of the mode increased with increasing NOx emission while the soot mode size and emission decreased simultaneously.

Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

PubMed

Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

2015-06-01

It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed to be higher with the cyclic flow (170 as MIF) than with the equivalent constant flow (170 l min(-1)). For 50 and 80% RH levels, the penetrations were usually greater with a constant flow (170 l min(-1)) than with a cyclic flow (170 l min(-1) as MIF). It is concluded that, for the tested electrostatic N95 filters, the change in penetration as a function of the loading time does not necessarily take place with the same rate under constant (MIF) and cyclic flow. Moreover, for all tested flow rates, the penetration is not only affected by the loading time but also by the RH level. Lower RH levels (10%) have decreasing penetration rates in terms of loading time, while higher RH levels (50 and 80%) have increasing penetration rates. Also, the loading of the filter is normally accompanied with a shift of MPPS towards larger sizes. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Image-based Lagrangian Particle Tracking in Bed-load Experiments.

PubMed

Radice, Alessio; Sarkar, Sankar; Ballio, Francesco

2017-07-20

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application of particle tracking velocimetry (PTV) to a bed-load experiment with lightweight sediment. The key characteristics of the investigated sediment transport conditions were the presence of a covered flow and of a fixed rough bed above which particles were released in limited number at the flume inlet. Under the applied flow conditions, the motion of the individual bed-load particles was intermittent, with alternating movement and stillness terms. The flow pattern was preliminarily characterized by acoustic measurements of vertical profiles of the stream-wise velocity. During process visualization, a large field of view was obtained using two action-cameras placed at different locations along the flume. The experimental protocol is described in terms of channel calibration, experiment realization, image pre-processing, automatic particle tracking, and post-processing of particle track data from the two cameras. The presented proof-of-concept results include probability distributions of the particle hop length and duration. The achievements of this work are compared to those of existing literature to demonstrate the validity of the protocol.

Iterative load-balancing method with multigrid level relaxation for particle simulation with short-range interactions

NASA Astrophysics Data System (ADS)

Furuichi, Mikito; Nishiura, Daisuke

2017-10-01

We developed dynamic load-balancing algorithms for Particle Simulation Methods (PSM) involving short-range interactions, such as Smoothed Particle Hydrodynamics (SPH), Moving Particle Semi-implicit method (MPS), and Discrete Element method (DEM). These are needed to handle billions of particles modeled in large distributed-memory computer systems. Our method utilizes flexible orthogonal domain decomposition, allowing the sub-domain boundaries in the column to be different for each row. The imbalances in the execution time between parallel logical processes are treated as a nonlinear residual. Load-balancing is achieved by minimizing the residual within the framework of an iterative nonlinear solver, combined with a multigrid technique in the local smoother. Our iterative method is suitable for adjusting the sub-domain frequently by monitoring the performance of each computational process because it is computationally cheaper in terms of communication and memory costs than non-iterative methods. Numerical tests demonstrated the ability of our approach to handle workload imbalances arising from a non-uniform particle distribution, differences in particle types, or heterogeneous computer architecture which was difficult with previously proposed methods. We analyzed the parallel efficiency and scalability of our method using Earth simulator and K-computer supercomputer systems.

Contact Electrification of Individual Dielectric Microparticles Measured by Optical Tweezers in Air.

PubMed

Park, Haesung; LeBrun, Thomas W

2016-12-21

We measure charging of single dielectric microparticles after interaction with a glass substrate using optical tweezers to control the particle, measure its charge with a sensitivity of a few electrons, and precisely contact the particle with the substrate. Polystyrene (PS) microparticles adhered to the substrate can be selected based on size, shape, or optical properties and repeatedly loaded into the optical trap using a piezoelectric (PZT) transducer. Separation from the substrate leads to charge transfer through contact electrification. The charge on the trapped microparticles is measured from the response of the particle motion to a step excitation of a uniform electric field. The particle is then placed onto a target location of the substrate in a controlled manner. Thus, the triboelectric charging profile of the selected PS microparticle can be measured and controlled through repeated cycles of trap loading followed by charge measurement. Reversible optical trap loading and manipulation of the selected particle leads to new capabilities to study and control successive and small changes in surface interactions.

Ultrafine particle emissions by in-use diesel buses of various generations at low-load regimes

NASA Astrophysics Data System (ADS)

Tartakovsky, L.; Baibikov, V.; Comte, P.; Czerwinski, J.; Mayer, A.; Veinblat, M.; Zimmerli, Y.

2015-04-01

Ultrafine particles (UFP) are major contributors to air pollution due to their easy gas-like penetration into the human organism, causing adverse health effects. This study analyzes UFP emissions by buses of different technologies (from Euro II till Euro V EEV - Enhanced Environmentally-friendly Vehicle) at low-load regimes. Additionally, the emission-reduction potential of retrofitting with a diesel particle filter (DPF) is demonstrated. A comparison of the measured, engine-out, particle number concentrations (PNC) for buses of different technological generations shows that no substantial reduction of engine-out emissions at low-load operating modes is observed for newer bus generations. Retrofitting the in-use urban and interurban buses of Euro II till Euro IV technologies by the VERT-certified DPF confirmed its high efficiency in reduction of UFP emissions. Particle-count filtration efficiency values of the retrofit DPF were found to be extremely high - greater than 99.8%, similar to that of the OEM filter in the Euro V bus.

Three-dimensional boron particle loaded thermal neutron detector

DOEpatents

Nikolic, Rebecca J.; Conway, Adam M.; Graff, Robert T.; Kuntz, Joshua D.; Reinhardt, Catherine; Voss, Lars F.; Cheung, Chin Li; Heineck, Daniel

2014-09-09

Three-dimensional boron particle loaded thermal neutron detectors utilize neutron sensitive conversion materials in the form of nano-powders and micro-sized particles, as opposed to thin films, suspensions, paraffin, etc. More specifically, methods to infiltrate, intersperse and embed the neutron nano-powders to form two-dimensional and/or three-dimensional charge sensitive platforms are specified. The use of nano-powders enables conformal contact with the entire charge-collecting structure regardless of its shape or configuration.

The influence of particle shape on dielectric enhancement in metal-insulator composites

NASA Astrophysics Data System (ADS)

Doyle, W. T.; Jacobs, I. S.

1992-04-01

Disordered suspensions of conducting particles exhibit substantial permittivity enhancements beyond the predictions of the Clausius-Mossotti equation and other purely dipolar approximations. The magnitude of the enhancement depends upon the shape of the particles. A recently developed effective cluster model for spherical particles [Phys. Rev. B 42, 9319 (1990)] that treats a disordered suspension as a mixture, or mesosuspension, of isolated spheres and close-packed spherical clusters of arbitrary size is in excellent agreement with experiments on well-stirred suspensions of spheres over the entire accessible range of volume loading. In this paper, the effective cluster model is extended to be applicable to disordered suspensions of arbitrarily shaped conducting particles. Two physical parameters are used to characterize a general suspension: the angular average polarizability of an isolated particle, and the volume loading at closest packing of the suspension. Multipole interactions within the clusters are treated exactly. External particle-shape-dependent interactions between clusters and isolated particles are treated in the dipole approximation in two ways: explicitly, using the Clausius-Mossotti equation, and implicitly, using the Wiener equation. Both versions of the model are used to find the permittivity of a monodisperse suspension of conducting spheroids, for which the model parameters can be determined independently. The two versions are in good agreement when the axial ratio of the particles is not extreme. The Clausius-Mossotti version of the model yields a mesoscopic analogue of the dielectric virial expansion. It is limited to small volume loadings when the particles have an extremely nonspherical shape. The Wiener equation version of the model holds at all volume loadings for particles of arbitrary shape. Comparison of the two versions of the model leads to a simple physical interpretation of Wiener's equation. The models are compared with experiments of Kelly, Stenoien, and Isbell [J. Appl. Phys. 24, 258 (1953)] on aluminum and zinc particles in paraffin, with Nasuhoglu's experiments on iron particles in oil [Commun. Fac. Sci. Univ. Ankara 4, 108 (1952)], and with new X-band and Kα-band permittivity measurements on Ni-Cr alloy particles in a polyurethane binder.

Suspended sediment measurements and calculation of the particle load at HPP Fieschertal

NASA Astrophysics Data System (ADS)

Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.

2016-11-01

In the scope of a research project on hydro-abrasive erosion of Pelton turbines, a field study was conducted at the high-head HPP Fieschertal in Valais, Switzerland. The suspended sediment mass concentration (SSC) and particle size distribution (PSD) in the penstock have been continuously measured since 2012 using a combination of six measuring techniques. The SSC was on average 0.52 g/l and rose to 50 g/l in a major flood event in July 2012. The median particle size d 50 was usually 15 pm, rising up to 100 μm when particles previously having settled in the headwater storage tunnel were re-suspended at low water levels. The annual suspended sediment loads (SSL) varied considerably depending on flood events. Moreover, so-called particle loads (PLs) according to the relevant guideline of the International Electrotechnical Commission (IEC 62364) were calculated using four relations between particle size and the relative abrasion potential. For the investigated HPP, the time series of the SSL and the PLs had generally similar shapes over the three years. The largest differences among the PLs were observed during re-suspension events when the particles were considerably coarser than usual. Further investigations on the effects of particle sizes on hydroabrasive erosion of splitters and cut-outs of coated Pelton turbines are recommended.

The Plasma Simulation Code: A modern particle-in-cell code with patch-based load-balancing

NASA Astrophysics Data System (ADS)

Germaschewski, Kai; Fox, William; Abbott, Stephen; Ahmadi, Narges; Maynard, Kristofor; Wang, Liang; Ruhl, Hartmut; Bhattacharjee, Amitava

2016-08-01

This work describes the Plasma Simulation Code (PSC), an explicit, electromagnetic particle-in-cell code with support for different order particle shape functions. We review the basic components of the particle-in-cell method as well as the computational architecture of the PSC code that allows support for modular algorithms and data structure in the code. We then describe and analyze in detail a distinguishing feature of PSC: patch-based load balancing using space-filling curves which is shown to lead to major efficiency gains over unbalanced methods and a previously used simpler balancing method.

Particle and Gas Emissions from an In Situ Burn of Crude Oil on the Ocean.

PubMed

Hobbs, John L Ross Ronald J Ferek And Peter V

1996-03-01

Burning is a very effective way of removing oil spills from the ocean; the tradeoff is the potential for significant air pollution. Airborne measurements are described for particles and gases from two test burns of crude oil offshore of St. Johns, Newfoundland during the Newfoundland Offshore Burn Experiment (NOBE). The smoke plumes from the burns initially rose 200-400 m into the air and then continued to rise and disperse laterally downwind. The concentrations of accumulation-mode particles in the smoke were ~45,000 cm -3 at 1.5 km from the fires, and they remained as high as ~4,000 cm -3 after an hour or more of travel time downwind. Total particle mass loadings in the plumes were over 1000 µg m -3 near the fires, but decreased to ~100 µg m -3 at 25 km downwind. For each kilogram of fuel consumed, ~770 g of carbon was released in the form of CO2, ~13 g of carbon as CO, -5 g as volatile organic compounds (VOCs), and -87 g as particles with diameters <3.5 µm, of which ~66 g was elemental carbon and ~7 g condensed organic carbon. Also, ~3 g of SO2 was released per kilogram of fuel burned. A relatively low combustion efficiency was indicated by the average molar ratio of the concentration of CO to excess CO2 of 0.017. The molar ratio of NOX to excess CO2 typically varied from 0.3 x 10 -3 to 0.4 x 10 -3 , implying little fixation of atmospheric nitrogen and low concentrations of NOX. For comparison, the total smoke particle production rate in the NOBE burns was about the same as that for a nineacre slash burn.

Terrestrial in situ sampling of dust devils (relative particle loads and vertical grain size distributions) as an equivalent for martian dust devils.

NASA Astrophysics Data System (ADS)

Raack, J.; Dennis, R.; Balme, M. R.; Taj-Eddine, K.; Ori, G. G.

2017-12-01

Dust devils are small vertical convective vortices which occur on Earth and Mars [1] but their internal structure is almost unknown. Here we report on in situ samples of two active dust devils in the Sahara Desert in southern Morocco [2]. For the sampling we used a 4 m high aluminium pipe with sampling areas made of removable adhesive tape. We took samples between 0.1-4 m with a sampling interval of 0.5 m and between 0.5-2 m with an interval of 0.25 m, respectively. The maximum diameter of all particles of the different sampling heights were then measured using an optical microscope to gain vertical grain size distributions and relative particle loads. Our measurements imply that both dust devils have a general comparable internal structure despite their different strengths and dimensions which indicates that the dust devils probably represents the surficial grain size distribution they move over. The particle sizes within the dust devils decrease nearly exponential with height which is comparable to results by [3]. Furthermore, our results show that about 80-90 % of the total particle load were lifted only within the first meter, which is a direct evidence for the existence of a sand skirt. If we assume that grains with a diameter <31 μm can go into suspension [4], our results show that only less than 0.1 wt% can be entrained into the atmosphere. Although this amount seems very low, these values represent between 60 and 70 % of all lifted particles due to the small grain sizes and their low weight. On Mars, the amount of lifted particles will be general higher as the dust coverage is larger [5], although the atmosphere can only suspend smaller grain sizes ( <20 μm) [6] compared to Earth. During our field campaign we observed numerous larger dust devils each day which were up to several hundred meters tall and had diameters of several tens of meters. This implies a much higher input of fine grained material into the atmosphere (which will have an influence on the climate, weather, and human health [7]) compared to the relative small dust devils sampled during our field campaign. [1] Thomas and Gierasch (1985) Science 230 [2] Raack et al. (2017) Astrobiology [3] Oke et al. (2007) J. Arid Environ. 71 [4] Balme and Greeley (2006) Rev. Geophys. 44 [5] Christensen (1986) JGR 91 [6] Newman et al. (2002) JGR 107 [7] Gillette and Sinclair (1990) Atmos. Environ. 24

Nitrogen and phosphorus removed from a subsurface flow multi-stage filtration system purifying agricultural runoff.

PubMed

Zhao, Yaqi; Huang, Lei; Chen, Yucheng

2018-07-01

Agricultural nonpoint source pollution has been increasingly serious in China since the 1990s. The main causes were excessive inputs of nitrogen fertilizer and pesticides. A multi-stage filtration system was built to test the purification efficiencies and removal characteristics of nitrogen and phosphorus when treating agricultural runoff. Simulated runoff pollution was prepared by using river water as source water based on the monitoring of local agricultural runoff. Experimental study had been performed from September to November 2013, adopting 12 h for flooding and 12 h for drying. The results showed that the system was made adaptive to variation of inflow quality and quantity, and had good removal for dissolved total nitrogen, total nitrogen, dissolved total phosphorus (DTP), and total phosphorus, and the average removal rate was 27%, 36%, 32%, and 48%, respectively. Except nitrate ([Formula: see text]), other forms of nitrogen and phosphorus all decreased with the increase of stages. Nitrogen was removed mainly in particle form the first stage, and mostly removed in dissolved form the second and third stage. Phosphorus was removed mainly in particulate during the first two stages, but the removal of particulate phosphorus and DTP were almost the same in the last stage. An approximate logarithmic relationship between removal loading and influent loading to nitrogen and phosphorus was noted in the experimental system, and the correlation coefficient was 0.78-0.94. [Formula: see text]: ammonium; [Formula: see text]: nitrite; [Formula: see text]: nitrate; DTN: dissolved total nitrogen; TN: total nitrogen; DTP: dissolved total phosphorus; TP: total phosphorus; PN: particulate nitrogen; PP: particulate phosphorus.

Equitable fund allocation, an economical approach for sustainable waste load allocation.

PubMed

Ashtiani, Elham Feizi; Niksokhan, Mohammad Hossein; Jamshidi, Shervin

2015-08-01

This research aims to study a novel approach for waste load allocation (WLA) to meet environmental, economical, and equity objectives, simultaneously. For this purpose, based on a simulation-optimization model developed for Haraz River in north of Iran, the waste loads are allocated according to discharge permit market. The non-dominated solutions are initially achieved through multiobjective particle swarm optimization (MOPSO). Here, the violation of environmental standards based on dissolved oxygen (DO) versus biochemical oxidation demand (BOD) removal costs is minimized to find economical total maximum daily loads (TMDLs). This can save 41% in total abatement costs in comparison with the conventional command and control policy. The BOD discharge permit market then increases the revenues to 45%. This framework ensures that the environmental limits are fulfilled but the inequity index is rather high (about 4.65). For instance, the discharge permit buyer may not be satisfied about the equity of WLA. Consequently, it is recommended that a third party or institution should be in charge of reallocating the funds. It means that the polluters which gain benefits by unfair discharges should pay taxes (or funds) to compensate the losses of other polluters. This intends to reduce the costs below the required values of the lowest inequity index condition. These compensations of equitable fund allocation (EFA) may help to reduce the dissatisfactions and develop WLA policies. It is concluded that EFA in integration with water quality trading (WQT) is a promising approach to meet the objectives.

Design of pH-responsive nanoparticles of terpolymer of poly(methacrylic acid), polysorbate 80 and starch for delivery of doxorubicin.

PubMed

Shalviri, Alireza; Chan, Ho Ka; Raval, Gaurav; Abdekhodaie, Mohammad J; Liu, Qiang; Heerklotz, Heiko; Wu, Xiao Yu

2013-01-01

This work focused on the design of new pH-responsive nanoparticles for controlled delivery of anticancer drug doxorubicin (Dox). Nanoparticles of poly(methacrylic acid)-polysorbate 80-grafted starch (PMAA-PS 80-g-St) were synthesized by using a one-pot method that enabled simultaneous grafting of PMAA and PS 80 onto starch and nanoparticle formation in an aqueous medium. The particles were characterized by FTIR, (1)H NMR, TEM, DLS, and potentiometric titration. Dox loading and in vitro release from the nanoparticles were investigated. The FTIR and (1)H NMR confirmed the chemical composition of the graft terpolymer. The nanoparticles were relatively spherical with narrow size distribution and porous morphology. They exhibited pH-dependent swelling in a physiological pH range. The particle size and magnitude of phase transition were dependent on polymer composition and formulation parameters such as concentrations of surfactant and cross-linking agent and total monomer concentration. The nanoparticles with optimized compositions showed high loading capacity for Dox and sustained Dox release. The results suggest that the new pH-responsive terpolymer nanoparticles are useful in controlled drug delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

Dynamic load balancing algorithm for molecular dynamics based on Voronoi cells domain decompositions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fattebert, J.-L.; Richards, D.F.; Glosli, J.N.

2012-12-01

We present a new algorithm for automatic parallel load balancing in classical molecular dynamics. It assumes a spatial domain decomposition of particles into Voronoi cells. It is a gradient method which attempts to minimize a cost function by displacing Voronoi sites associated with each processor/sub-domain along steepest descent directions. Excellent load balance has been obtained for quasi-2D and 3D practical applications, with up to 440·10 6 particles on 65,536 MPI tasks.

Modeling of the processes of natural and waste water purification in the reactor-clarifier

NASA Astrophysics Data System (ADS)

Primak, O. D.; Skolubovich, Yu. L.; Fedorova, N. N.; Voitov, E. L.

2018-03-01

The results of the filtration process simulation in a reactor-clarifier installation using a suspended loading layer are presented. Calculations were carried out in ANSYS Fluent on the basis of the Navier-Stokes equations supplemented by the equations of the Eulerian model of multiphase taking into account granularity of the particle phase. The unsteady picture of the formation of a fluidized («boiling») layer of particles is obtained. The results of parametric calculations allowing to estimate the effect of the flow velocity, the loading layer thickness, the thickness of sand and other parameters on the fluidized bed structure are presented. The liquid flow rate at which the loading grains are not washed out is determined. The diameter of particles and the height of the loading layer, at which the filter material is suspended and thus normal operation of the plant is ensured, are defined.

Sequential and simultaneous thermal and particle exposure of tungsten

NASA Astrophysics Data System (ADS)

Steudel, I.; Huber, A.; Kreter, A.; Linke, J.; Sergienko, G.; Unterberg, B.; Wirtz, M.

2016-02-01

The broad array of expected loading conditions in a fusion reactor such as ITER necessitates high requirements on the plasma facing materials (PFMs). Tungsten, the PFM for the divertor region, the most affected part of the in-vessel components, must thus sustain severe, distinct exposure conditions. Accordingly, comprehensive experiments investigating sequential and simultaneous thermal and particle loads were performed on double forged pure tungsten, not only to investigate whether the thermal and particle loads cause damage but also if the sequence of exposure maintains an influence. The exposed specimens showed various kinds of damage such as roughening, blistering, and cracking at a base temperature where tungsten could be ductile enough to compensate the induced stresses exclusively by plastic deformation (Pintsuk et al 2011 J. Nucl. Mater. 417 481-6). It was found out that hydrogen has an adverse effect on the material performance and the loading sequence on the surface modification.

Development of albumin-based nanoparticles for the delivery of abacavir.

PubMed

Wilson, Barnabas; Paladugu, Latishkumar; Priyadarshini, S R Brahmani; Jenita, J Josephine Leno

2015-11-01

The study was designed to prepare and evaluate albumin nanoparticles containing antiviral drug abacavir sulphate. Various batches of albumin nanoparticles containing abacavir sulphate were prepared by desolvation method. The abacavir loaded particles were characterized for their yield, percentage of drug loading, surface morphology, particle size, surface charge, pattern of in vitro drug release and release mechanism studies. Drug loading ranged from 1.2 to 5.9%w/w. The mean particle size and the surface charge were 418.2nm and -40.8mV respectively. The in vitro drug release varied between 38.73 and 51.36%w/w for 24h. The n value for Korsmeyer-Peppas was 0.425 indicating Fickian type drug release. The preliminary findings indicated that albumin nanoparticles of abacavir can be prepared by desolvation method with good yield, high drug loading and sustained release. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of particle size distribution on the blast pressure profile from explosives buried in saturated soils

NASA Astrophysics Data System (ADS)

Rigby, S. E.; Fay, S. D.; Tyas, A.; Clarke, S. D.; Reay, J. J.; Warren, J. A.; Gant, M.; Elgy, I.

2018-05-01

The spatial and temporal distribution of pressure and impulse from explosives buried in saturated cohesive and cohesionless soils has been measured experimentally for the first time. Ten experiments have been conducted at quarter-scale, where localised pressure loading was measured using an array of 17 Hopkinson pressure bars. The blast pressure measurements are used in conjunction with high-speed video filmed at 140,000 fps to investigate in detail the physical processes occurring at the loaded face. Two coarse cohesionless soils and one fine cohesive soil were tested: a relatively uniform sand, a well-graded sandy gravel, and a fine-grained clay. The results show that there is a single fundamental loading mechanism when explosives are detonated in saturated soil, invariant of particle size and soil cohesion. It is also shown that variability in localised loading is intrinsically linked to the particle size distribution of the surrounding soil.

Coupling fine particle and bedload transport in gravel-bedded streams

NASA Astrophysics Data System (ADS)

Park, Jungsu; Hunt, James R.

2017-09-01

Fine particles in the silt- and clay-size range are important determinants of surface water quality. Since fine particle loading rates are not unique functions of stream discharge this limits the utility of the available models for water quality assessment. Data from 38 minimally developed watersheds within the United States Geological Survey stream gauging network in California, USA reveal three lines of evidence that fine particle release is coupled with bedload transport. First, there is a transition in fine particle loading rate as a function of discharge for gravel-bedded sediments that does not appear when the sediment bed is composed of sand, cobbles, boulders, or bedrock. Second, the discharge at the transition in the loading rate is correlated with the initiation of gravel mobilization. Third, high frequency particle concentration and discharge data are dominated by clockwise hysteresis where rising limb discharges generally have higher concentrations than falling limb discharges. These three observations across multiple watersheds lead to a conceptual model that fine particles accumulate within the sediment bed at discharges less than the transition and then the gravel bed fluidizes with fine particle release at discharges above the transition discharge. While these observations were individually recognized in the literature, this analysis provides a consistent conceptual model based on the coupling of fine particle dynamics with filtration at low discharges and gravel bed fluidization at higher discharges.

Short term load forecasting of anomalous load using hybrid soft computing methods

NASA Astrophysics Data System (ADS)

Rasyid, S. A.; Abdullah, A. G.; Mulyadi, Y.

2016-04-01

Load forecast accuracy will have an impact on the generation cost is more economical. The use of electrical energy by consumers on holiday, show the tendency of the load patterns are not identical, it is different from the pattern of the load on a normal day. It is then defined as a anomalous load. In this paper, the method of hybrid ANN-Particle Swarm proposed to improve the accuracy of anomalous load forecasting that often occur on holidays. The proposed methodology has been used to forecast the half-hourly electricity demand for power systems in the Indonesia National Electricity Market in West Java region. Experiments were conducted by testing various of learning rate and learning data input. Performance of this methodology will be validated with real data from the national of electricity company. The result of observations show that the proposed formula is very effective to short-term load forecasting in the case of anomalous load. Hybrid ANN-Swarm Particle relatively simple and easy as a analysis tool by engineers.

Physicochemical aspects involved in methotrexate release kinetics from biodegradable spray-dried chitosan microparticles

NASA Astrophysics Data System (ADS)

Mesquita, Philippe C.; Oliveira, Alice R.; Pedrosa, Matheus F. Fernandes; de Oliveira, Anselmo Gomes; da Silva-Júnior, Arnóbio Antônio

2015-06-01

Spray dried methotrexate (MTX) loaded chitosan microparticles were prepared using different drug/copolymer ratios (9%, 18%, 27% and 45% w/w). The physicochemical aspects were assessed in order to select particles that were able to induce a sustained drug release effect. Particles were successfully produced which exhibited desired physicochemical aspects such as spherical shape and high drug loading. XRD and FT-IR analysis demonstrated that drug is not bound to copolymer and is only homogeneously dispersed in an amorphous state into polymeric matrix. Even the particles with higher drug loading levels presented a sustained drug release profile, which were mathematically modeled using adjusted Higuchi model. The drug release occurred predominantly with drug dissolution and diffusion through swollen polymeric matrix, with the slowest release occurring with particles containing 9% of drug, demonstrating an interesting and promising drug delivery system for MTX.

Particle morphology dependent superhydrophobicity in treated diatomaceous earth/polystyrene coatings

NASA Astrophysics Data System (ADS)

Sedai, Bhishma R.; Alavi, S. Habib; Harimkar, Sandip P.; McCollum, Mark; Donoghue, Joseph F.; Blum, Frank D.

2017-09-01

Superhydrophobic surfaces have been prepared from three different types of diatomaceous earth (DE) particles treated with 3-(heptafluoroisopropoxy)propyltrimethoxysilane (HFIP-TMS) and low molecular mass polystyrene. The untreated particles, consisting of CelTix DE (disk shape), DiaFil DE (rod shape) and EcoFlat DE (irregular), were studied using particle size analysis, bulk density, pore volume and surface area analysis (via Brunauer-Emmett-Teller, BET, methods). The treated particles were characterized with thermogravimetric analysis (TGA), contact angles, scanning electron microscopy, profilometry, and FTIR spectroscopy. The minimum amount of silane coupling agent on the DE surfaces required to obtain superhydrophobicity of the particles was determined and found to be dependent on the particle morphology. In the coatings made from different particles with 2.4 wt% HFIP-TMS, the minimum amounts of treated particles (loadings) for superhydrophobicity was determined with the less dense CelTix DE requiring about 30 wt%, DiaFil DE requiring about 40 wt%, and EcoFlat DE each requiring about 60 wt% loading of treated particles.

A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shanhui; Tong, Chaohui; Zhu, Yuejin, E-mail: zhuyuejin@nbu.edu.cn

The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. Whenmore » the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.« less

Calcium alginate particles for the combined delivery of platelet lysate and vancomycin hydrochloride in chronic skin ulcers.

PubMed

Mori, Michela; Rossi, Silvia; Bonferoni, Maria Cristina; Ferrari, Franca; Sandri, Giuseppina; Riva, Federica; Del Fante, Claudia; Perotti, Cesare; Caramella, Carla

2014-01-30

The aim of the present work was the development of a powder formulation for the combined delivery of platelet lysate and of a model antibiotic drug, vancomycin hydrochloride (VCM), in chronic skin ulcers. Calcium alginate particles were prepared by freeze-drying beads obtained by ionic gelation method. The experimental conditions adopted permitted the complete loading of VCM and of PDGF AB, the growth factor chosen as representative of those contained in PL. Such particles where able to absorb PBS (mimicking wound exudate), to form a gel and to modulate the release of VCM and of PDGF AB. They are characterized by enhancement properties of human fibroblast proliferation due to PL presence. In particular, PL, when loaded in alginate particles, was able not only to increase the number of viable cells, but also the number of cells in proliferative phase. Such properties were comparable to those of fresh PL indicating the capability of calcium alginate particles to load PL bioactive substances without altering their activity. The formulation developed is characterized by an easier and a less painful administration with respect to traditional gauzes and semisolid preparations and permits the loading in the same dosage form of active substances of different nature avoiding eventual incompatibility problems. Copyright © 2013 Elsevier B.V. All rights reserved.

Sediment load and distribution in the lower Skagit River, Skagit County, Washington

USGS Publications Warehouse

Curran, Christopher A.; Grossman, Eric E.; Mastin, Mark C.; Huffman, Raegan L.

2016-08-17

The Skagit River delivers about 40 percent of all fluvial sediment that enters Puget Sound, influencing flood hazards in the Skagit lowlands, critically important estuarine habitat in the delta, and some of the most diverse and productive agriculture in western Washington. A total of 175 measurements of suspended-sediment load, made routinely from 1974 to 1993, and sporadically from 2006 to 2009, were used to develop and evaluate regression models of sediment transport (also known as “sediment-rating curves”) for estimating suspended-sediment load as a function of river discharge. Using a flow-range model and 75 years of daily discharge record (acquired from 1941 to 2015), the mean annual suspended-sediment load for the Skagit River near Mount Vernon, Washington, was estimated to be 2.5 teragrams (Tg, where 1 Tg = 1 million metric tons). The seasonal model indicates that 74 percent of the total annual suspended‑sediment load is delivered to Puget Sound during the winter storm season (from October through March), but also indicates that discharge is a poor surrogate for suspended‑sediment concentration (SSC) during the summer low-flow season. Sediment-rating curves developed for different time periods revealed that the regression model slope of the SSC-discharge relation increased 66 percent between the periods of 1974–76 and 2006–09 when suspended-sediment samples were collected, implying that changes in sediment supply, channel hydraulics, and (or) basin hydrology occurred between the two time intervals. In the relatively wet water year 2007 (October 1, 2006, through September 30, 2007), an automated sampler was used to collect daily samples of suspended sediment from which an annual load of 4.5 Tg was calculated, dominated by a single large flood event that contributed 1.8 Tg, or 40 percent of the total. In comparison, the annual load calculated for water year 2007 using the preferred flow-range model was 4.8 Tg (+6.7 percent), in close agreement with the measured value.Particle size affects sediment transport, fate and distribution across watersheds, and therefore is important for predicting how coastal environments, particularly deltas and beaches, will respond to changes in climate and sea-level. Particle-size analysis of winter storm samples indicated that about one-half of the suspended-sediment load consisted of fines (that is, silt- and clay-sized particles smaller than 0.0625 mm in diameter), and the remainder consisted of mostly fine- to medium-sized sand (0.0625–0.5 mm), whereas bedload during winter storm flows (about 1–3 percent of total sediment load) was predominantly composed of medium to coarse sand (0.25–1 mm). A continuous turbidity record from the Anacortes Water Treatment Plant (water years 1999–2013), used as a surrogate for the concentration of fines (R2 = 0.93, p = 4.2E-10, n = 17), confirms that about one-half of the mean annual suspended-sediment load is composed of fines.The distribution of flow through the delta distributaries (that is, the channels into which the main stem splits as it approaches the delta) is dynamic, with twice as much flow through the North Fork of the Skagit River relative to the South Fork during low-flow conditions, and close to equal flows in the two channels during high-flow conditions. Turbidity, monitored at several locations in the lower river in spring 2009, was essentially uniform among sites, indicating that fines are well mixed in the lower Skagit River system (defined as the Skagit River and all its distributaries downstream of the Mount Vernon streamgage). A strong relation (R2 = 0.95, p = 3.2E-14, n = 21; linear regression) between the concentration of fines and turbidity measured at various locations in summer 2009 indicates that turbidity is an effective surrogate for the concentration of fines, independent of location in the river, under naturally well-mixed fluvial conditions. This relation is especially useful for monitoring suspended sediment in western Washington rivers that are seasonally dominated by glacier meltwater because glacial melting typically produces suspended-sediment concentrations that are not well correlated with discharge. These results provide a comprehensive set of tools to estimate sediment delivery and delta responses of interest to scientists and resource managers including decision-makers examining options for flood hazard mitigation, estuary restoration, and climate change adaptation.

Nitrate radical oxidation of γ-terpinene: hydroxy nitrate, total organic nitrate, and secondary organic aerosol yields

NASA Astrophysics Data System (ADS)

Slade, Jonathan H.; de Perre, Chloé; Lee, Linda; Shepson, Paul B.

2017-07-01

Polyolefinic monoterpenes represent a potentially important but understudied source of organic nitrates (ONs) and secondary organic aerosol (SOA) following oxidation due to their high reactivity and propensity for multi-stage chemistry. Recent modeling work suggests that the oxidation of polyolefinic γ-terpinene can be the dominant source of nighttime ON in a mixed forest environment. However, the ON yields, aerosol partitioning behavior, and SOA yields from γ-terpinene oxidation by the nitrate radical (NO3), an important nighttime oxidant, have not been determined experimentally. In this work, we present a comprehensive experimental investigation of the total (gas + particle) ON, hydroxy nitrate, and SOA yields following γ-terpinene oxidation by NO3. Under dry conditions, the hydroxy nitrate yield = 4(+1/-3) %, total ON yield = 14(+3/-2) %, and SOA yield ≤ 10 % under atmospherically relevant particle mass loadings, similar to those for α-pinene + NO3. Using a chemical box model, we show that the measured concentrations of NO2 and γ-terpinene hydroxy nitrates can be reliably simulated from α-pinene + NO3 chemistry. This suggests that NO3 addition to either of the two internal double bonds of γ-terpinene primarily decomposes forming a relatively volatile keto-aldehyde, reconciling the small SOA yield observed here and for other internal olefinic terpenes. Based on aerosol partitioning analysis and identification of speciated particle-phase ON applying high-resolution liquid chromatography-mass spectrometry, we estimate that a significant fraction of the particle-phase ON has the hydroxy nitrate moiety. This work greatly contributes to our understanding of ON and SOA formation from polyolefin monoterpene oxidation, which could be important in the northern continental US and the Midwest, where polyolefinic monoterpene emissions are greatest.

Source apportionment of PAHs and n-alkanes in respirable particles in Tehran, Iran by wind sector and vertical profile.

PubMed

Moeinaddini, Mazaher; Esmaili Sari, Abbas; Riyahi bakhtiari, Alireza; Chan, Andrew Yiu-Chung; Taghavi, Seyed Mohammad; Hawker, Darryl; Connell, Des

2014-06-01

The vertical concentration profiles and source contributions of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes in respirable particle samples (PM4) collected at 10, 100, 200 and 300-m altitude from the Milad Tower of Tehran, Iran during fall and winter were investigated. The average concentrations of total PAHs and total n-alkanes were 16.7 and 591 ng/m(3), respectively. The positive matrix factorization (PMF) model was applied to the chemical composition and wind data to apportion the contributing sources. The five PAH source factors identified were: 'diesel' (56.3% of total PAHs on average), 'gasoline' (15.5%), 'wood combustion, and incineration' (13%), 'industry' (9.2%), and 'road soil particle' (6.0%). The four n-alkane source factors identified were: 'petrogenic' (65% of total n-alkanes on average), 'mixture of petrogenic and biomass burning' (15%), 'mixture of biogenic and fossil fuel' (11.5%), and 'biogenic' (8.5%). Source contributions by wind sector were also estimated based on the wind sector factor loadings from PMF analysis. Directional dependence of sources was investigated using the conditional probability function (CPF) and directional relative strength (DRS) methods. The calm wind period was found to contribute to 4.4% of total PAHs and 5.0% of total n-alkanes on average. Highest average concentrations of PAHs and n-alkanes were found in the 10 and 100 m samples, reflecting the importance of contributions from local sources. Higher average concentrations in the 300 m samples compared to those in the 200 m samples may indicate contributions from long-range transport. The vertical profiles of source factors indicate the gasoline and road soil particle-associated PAHs, and the mixture from biogenic and fossil fuel source-associated n-alkanes were mostly from local emissions. The smaller average contribution of diesel-associated PAHs in the lower altitude samples also indicates that the restriction of diesel-fueled vehicle use in the central area of Tehran has been effective in reducing the PAHs concentration.

Transport of nitrogen in a treated-wastewater plume to coastal discharge areas, Ashumet Valley, Cape Cod, Massachusetts

USGS Publications Warehouse

Barbaro, Jeffrey R.; Walter, Donald A.; LeBlanc, Denis R.

2013-01-01

Land disposal of treated wastewater from a treatment plant on the Massachusetts Military Reservation in operation from 1936 to 1995 has created a plume of contaminated groundwater that is migrating toward coastal discharge areas in the town of Falmouth, Massachusetts. To develop a better understanding of the potential impact of the treated-wastewater plume on coastal discharge areas, the U.S. Geological Survey, in cooperation with the Air Force Center for Engineering and the Environment, evaluated the fate of nitrogen (N) in the plume. Groundwater samples from two large sampling events in 1994 and 2007 were used to map the size and location of the plume, calculate the masses of nitrate-N and ammonium-N, evaluate changes in mass since cessation of disposal in 1995, and create a gridded dataset suitable for use in nitrogen-transport simulations. In 2007, the treated-wastewater plume was about 1,200 meters (m) wide, 30 m thick, and 7,700 m long and contained approximately 87,000 kilograms (kg) nitrate-N and 31,600 kg total ammonium-N. An analysis of previous studies and data from 1994 and 2007 sampling events suggests that most of biologically reactive nitrogen in the plume in 2007 will be transported to coastal discharge areas as either nitrate or ammonium with relatively little transformation to an environmentally nonreactive end product such as nitrogen gas. Nitrogen-transport simulations were conducted with a previously calibrated regional three-dimensional MODFLOW groundwater flow model. Mass-loaded particle tracking was used to simulate the advective transport of nitrogen to discharge areas (or receptors) along the coast. In the simulations, nonreactive transport (no mass loss in the aquifer) was assumed, providing an upper-end estimate of nitrogen loads to receptors. Simulations indicate that approximately 95 percent of the nitrate-N and 99 percent of the ammonium-N in the wastewater plume will eventually discharge to the Coonamessett River, Backus River, Green Pond, and Bournes River. Approximately 76 percent of the total nitrate-N mass in the plume will discharge to these receptors within 100 years of 2007; 90 and 94 percent will discharge within 200 and 500 years, respectively. Nitrate loads will peak within about 50 years at all of the major receptors. The highest peak loads will occur at the Coonamessett River (450 kg per year (kg/yr) nitrate-N) and the Backus River (350 kg/yr nitrate-N). Because of adsorption, travel times are longer for ammonium than for nitrate; approximately 5 percent of the total ammonium-N mass in the plume will discharge to receptors within 100 years; 46 and 81 percent will discharge within 200 and 500 years, respectively. The simulations indicate that the Coonamessett River will receive the largest cumulative nitrogen mass and the highest rate of discharge (load). Ongoing discharge to Ashumet Pond is relatively minor because most of the wastewater plume mass has already migrated downgradient from the pond. To evaluate the contribution of the nitrogen loads from the treated-wastewater plume to total nitrogen loads to the discharge areas, the simulated treated-wastewater plume loads were compared to steady-state nonpoint-source loads calculated by the Massachusetts Estuaries Project for 2005. Simulation results indicate that the total nitrogen loads from the treated-wastewater plume are much lower than corresponding steady-state nonpoint-source loads from the watersheds; peak plume loads are equal to 11 percent or less of the nonpoint-source loads.

Sampling, testing and modeling particle size distribution in urban catch basins.

PubMed

Garofalo, G; Carbone, M; Piro, P

2014-01-01

The study analyzed the particle size distribution of particulate matter (PM) retained in two catch basins located, respectively, near a parking lot and a traffic intersection with common high levels of traffic activity. Also, the treatment performance of a filter medium was evaluated by laboratory testing. The experimental treatment results and the field data were then used as inputs to a numerical model which described on a qualitative basis the hydrological response of the two catchments draining into each catch basin, respectively, and the quality of treatment provided by the filter during the measured rainfall. The results show that PM concentrations were on average around 300 mg/L (parking lot site) and 400 mg/L (road site) for the 10 rainfall-runoff events observed. PM with a particle diameter of <45 μm represented 40-50% of the total PM mass. The numerical model showed that a catch basin with a filter unit can remove 30 to 40% of the PM load depending on the storm characteristics.

Evaluation of hirst-type spore trap to monitor environmental fungal load in hospital

PubMed Central

Gustin, Marie-Paule; Cassier, Pierre; Loeffert, Sophie Tiphaine; Thibaudon, Michel; Bénet, Thomas; Vanhems, Philippe

2017-01-01

The main purpose was to validate the use of outdoor-indoor volumetric impaction sampler with Hirst-type spore traps (HTSTs) to continuously monitor fungal load in order to prevent invasive fungal infections during major structural work in hospital settings. For 4 weeks, outdoor fungal loads were quantified continuously by 3 HTSTs. Indoor air was sampled by both HTST and viable impaction sampler. Results were expressed as particles/m3 (HTST) or colony-forming units (CFU)/m3 (biocollector). Paired comparisons by day were made with Wilcoxon’s paired signed-rank test or paired Student’s t-test as appropriate. Paired airborne spore levels were correlated 2 by 2, after log-transformation with Pearson’s cross-correlation. Concordance was calculated with kappa coefficient (κ). Median total fungal loads (TFLs) sampled by the 3 outdoor HTSTs were 3,025.0, 3,287.5 and 3,625.0 particles/m3 (P = 0.6, 0.6 and 0.3).—Concordance between Aspergillaceae fungal loads (AFLs, including Aspergillus spp. + Penicillium spp.) was low (κ = 0.2). A low positive correlation was found between TFLs sampled with outdoor HTST and indoor HTST with applying a 4-hour time lag, r = 0.30, 95% CI (0.23–0.43), P<0.001. In indoor air, Aspergillus spp. were detected by the viable impaction sampler on 63.1% of the samples, whereas AFLs were found by HTST-I on only 3.6% of the samples. Concordance between Aspergillus spp. loads and AFLs sampled with the 2 methods was very low (κ = 0.1). This study showed a 4-hour time lag between increase of outdoor and indoor TFLs, possibly due to insulation and aeraulic flow of the building. Outdoor HTSTs may permit to quickly identify (after 48 hours) time periods with high outdoor fungal loads. An identified drawback is that a too low sample area read did not seem to enable detection of Aspergillaceae spores efficiently. Indoor HTSTs may not be recommended at this time, and outdoor HTSTs need further study. Air sampling by viable impaction sampler remains the reference tool for quantifying fungal contamination of indoor air in hospitals. PMID:28486534

Evaluation of hirst-type spore trap to monitor environmental fungal load in hospital.

PubMed

Dananché, Cédric; Gustin, Marie-Paule; Cassier, Pierre; Loeffert, Sophie Tiphaine; Thibaudon, Michel; Bénet, Thomas; Vanhems, Philippe

2017-01-01

The main purpose was to validate the use of outdoor-indoor volumetric impaction sampler with Hirst-type spore traps (HTSTs) to continuously monitor fungal load in order to prevent invasive fungal infections during major structural work in hospital settings. For 4 weeks, outdoor fungal loads were quantified continuously by 3 HTSTs. Indoor air was sampled by both HTST and viable impaction sampler. Results were expressed as particles/m3 (HTST) or colony-forming units (CFU)/m3 (biocollector). Paired comparisons by day were made with Wilcoxon's paired signed-rank test or paired Student's t-test as appropriate. Paired airborne spore levels were correlated 2 by 2, after log-transformation with Pearson's cross-correlation. Concordance was calculated with kappa coefficient (κ). Median total fungal loads (TFLs) sampled by the 3 outdoor HTSTs were 3,025.0, 3,287.5 and 3,625.0 particles/m3 (P = 0.6, 0.6 and 0.3).-Concordance between Aspergillaceae fungal loads (AFLs, including Aspergillus spp. + Penicillium spp.) was low (κ = 0.2). A low positive correlation was found between TFLs sampled with outdoor HTST and indoor HTST with applying a 4-hour time lag, r = 0.30, 95% CI (0.23-0.43), P<0.001. In indoor air, Aspergillus spp. were detected by the viable impaction sampler on 63.1% of the samples, whereas AFLs were found by HTST-I on only 3.6% of the samples. Concordance between Aspergillus spp. loads and AFLs sampled with the 2 methods was very low (κ = 0.1). This study showed a 4-hour time lag between increase of outdoor and indoor TFLs, possibly due to insulation and aeraulic flow of the building. Outdoor HTSTs may permit to quickly identify (after 48 hours) time periods with high outdoor fungal loads. An identified drawback is that a too low sample area read did not seem to enable detection of Aspergillaceae spores efficiently. Indoor HTSTs may not be recommended at this time, and outdoor HTSTs need further study. Air sampling by viable impaction sampler remains the reference tool for quantifying fungal contamination of indoor air in hospitals.

Real-time and integrated measurement of potential human exposure to particle-bound polycyclic aromatic hydrocarbons (PAHs) from aircraft exhaust.

PubMed Central

Childers, J W; Witherspoon, C L; Smith, L B; Pleil, J D

2000-01-01

We used real-time monitors and low-volume air samplers to measure the potential human exposure to airborne polycyclic aromatic hydrocarbon (PAH) concentrations during various flight-related and ground-support activities of C-130H aircraft at an Air National Guard base. We used three types of photoelectric aerosol sensors (PASs) to measure real-time concentrations of particle-bound PAHs in a break room, downwind from a C-130H aircraft during a four-engine run-up test, in a maintenance hangar, in a C-130H aircraft cargo bay during cargo-drop training, downwind from aerospace ground equipment (AGE), and in a C-130H aircraft cargo bay during engine running on/off (ERO) loading and backup exercises. Two low-volume air samplers were collocated with the real-time monitors for all monitoring events except those in the break room and during in-flight activities. Total PAH concentrations in the integrated-air samples followed a general trend: downwind from two AGE units > ERO-loading exercise > four-engine run-up test > maintenance hangar during taxi and takeoff > background measurements in maintenance hangar. Each PAH profile was dominated by naphthalene, the alkyl-substituted naphthalenes, and other PAHs expected to be in the vapor phase. We also found particle-bound PAHs, such as fluoranthene, pyrene, and benzo[a]pyrene in some of the sample extracts. During flight-related exercises, total PAH concentrations in the integrated-air samples were 10-25 times higher than those commonly found in ambient air. Real-time monitor mean responses generally followed the integrated-air sample trends. These monitors provided a semiquantitative temporal profile of ambient PAH concentrations and showed that PAH concentrations can fluctuate rapidly from a baseline level < 20 to > 4,000 ng/m(3) during flight-related activities. Small handheld models of the PAS monitors exhibited potential for assessing incidental personal exposure to particle-bound PAHs in engine exhaust and for serving as a real-time dosimeter to indicate when respiratory protection is advisable. PMID:11017890

Microspheres for the oral delivery of insulin: preparation, evaluation and hypoglycaemic effect in streptozotocin-induced diabetic rats.

PubMed

Zhang, Huan; Wang, Weimei; Li, Haoran; Peng, Yi; Zhang, Zhiqing

2018-01-01

Insulin-loaded microspheres were prepared by alternating deposition film layers that were composed of insulin and poly(vinyl sulfate) potassium on the surface of poly(lactic acid) (PLA) microspheres. The preparation of the insulin-loaded microspheres was optimized by an orthogonal test design, and the relationship between drug loading (DL) and film layers was studied. The particle size, DL and encapsulation efficiency of the obtained insulin-loaded microspheres with 10 films were 5.25 ± 0.15 µm, 111.33 ± 1.15 mg/g and 33.7 ± 0.19%, respectively. Following this, the physical characteristics of the insulin-loaded microspheres were investigated. The results from scanning electron microscopy and a laser particle size analyzer (LPSA) indicated the spherical morphology, rough surface and increasing particle sizes of the insulin-loaded microspheres, which were compared to those of PLA microspheres. An in vitro release study showed that the insulin-loaded microspheres were stable in HCl solution (pH 1.0) and released insulin slowly in phosphate-buffered solution (pH 6.8). Finally, the drug efficacy of the prepared insulin-loaded microspheres via oral administration was evaluated in rats with diabetes induced by streptozotocin, and an obvious dose-dependent hypoglycemic effect was observed. This preliminary data could illustrate the prospect of using microspheres for the oral delivery of insulin.

Wear characteristics of an unconstrained lumbar total disc replacement under a range of in vitro test conditions

PubMed Central

Fisher, John; Hall, Richard M.

2015-01-01

Abstract The effect of kinematics, loading and centre of rotation on the wear of an unconstrained total disc replacement have been investigated using the ISO 18192‐1 standard test as a baseline. Mean volumetric wear rate and surface morphological effects were reported. Changing the phasing of the flexions to create a low (but finite) amount of crossing path motion at the bearing surfaces resulted in a significant fall in wear volume. However, the rate of wear was still much larger than previously reported values under zero cross shear conditions. Reducing the load did not result in a significant change in wear rate. Moving the centre of rotation of the disc inferiorly did significantly increase wear rate. A phenomenon of debris re‐attachment on the UHMWPE surface was observed and hypothesised to be due to a relatively harsh tribological operating regime in which lubricant replenishment and particle migration out of the bearing contact zone were limited. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 46–52, 2017. PMID:26411540

Effects of ionic and nonionic surfactants on milk shell wettability during co-spray-drying of whole milk particles.

PubMed

Lallbeeharry, P; Tian, Y; Fu, N; Wu, W D; Woo, M W; Selomulya, C; Chen, X D

2014-09-01

Mixing surfactants with whole milk feed before spray drying could be a commercially favorable approach to produce instant whole milk powders in a single step. Pure whole milk powders obtained directly from spray drying often have a high surface fat coverage (up to 98%), rendering them less stable during storage and less wettable upon reconstitution. Dairy industries often coat these powders with lecithin, a food-grade surfactant, in a secondary fluidized-bed drying stage to produce instant powders. This study investigated the changes in wetting behavior on the surface of a whole milk particle caused by the addition of surfactants before drying. Fresh whole milk was mixed with 0.1% (wt/wt) Tween 80 or 1% (wt/wt) lecithin (total solids), and the wetting behavior of the shell formed by each sample was captured using a single-droplet drying device at intermediate drying stages as the shell was forming. The addition of surfactants improved shell wettability from the beginning of shell formation, producing more wettable milk particles after drying. The increase in surfactant loading by 10 times reduced the wetting time from around 30s to <5s. At the same loading of 1% (wt/wt; total solids), milk particles with Tween 80 were much more wettable than those with lecithin (<5s compared with >30s). We proposed that Tween 80 could adsorb at the oil-water interface of fat globules, making the surface fat more wettable, whereas lecithin tends to combine with milk proteins to form a complex, which then competes for the air-water surface with fat globules. Spray-drying experiments confirmed the greatly improved wettability of whole milk powders by the addition of either 0.1% (wt/wt) Tween 80 or 1% (wt/wt) lecithin; wetting time was reduced from 35±4s to <15s. To the best of our knowledge, this is the first time that a dynamic droplet drying system has been used to elucidate the complex interactions between ionic or nonionic surfactants and milk components (both proteins and fat), as well as the resultant effect on the development of milk particle functionality during drying. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Particle size distribution and perchlorate levels in settled dust from urban roads, parks, and roofs in Chengdu, China.

PubMed

Li, Yiwen; Shen, Yang; Pi, Lu; Hu, Wenli; Chen, Mengqin; Luo, Yan; Li, Zhi; Su, Shijun; Ding, Sanglan; Gan, Zhiwei

2016-01-01

A total of 27 settled dust samples were collected from urban roads, parks, and roofs in Chengdu, China to investigate particle size distribution and perchlorate levels in different size fractions. Briefly, fine particle size fractions (<250 μm) were the dominant composition in the settled dust samples, with mean percentages of 80.2%, 69.5%, and 77.2% for the urban roads, roofs, and the parks, respectively. Perchlorate was detected in all of the size-fractionated dust samples, with concentrations ranging from 73.0 to 6160 ng g(-1), and the median perchlorate levels increased with decreasing particle size. The perchlorate level in the finest fraction (<63 μm) was significantly higher than those in the coarser fractions. To our knowledge, this is the first report on perchlorate concentrations in different particle size fractions. The calculated perchlorate loadings revealed that perchlorate was mainly associated with finer particles (<125 μm). An exposure assessment indicated that exposure to perchlorate via settled road dust intake is safe to both children and adults in Chengdu, China. However, due to perchlorate mainly existing in fine particles, there is a potential for perchlorate to transfer into surface water and the atmosphere by runoff and wind erosion or traffic emission, and this could act as an important perchlorate pollution source for the indoor environment, and merits further study.

Considerations on the influence of extreme events on the phosphorus transport from river catchments to the sea.

PubMed

Zessner, M; Postolache, C; Clement, A; Kovacs, A; Strauss, P

2005-01-01

In this paper, results from rivers of different sizes in Romania, Hungary and Austria are presented. The paper shows the dynamics of extreme events and their contribution to the total P and suspended solids transported in these rivers. Special attention is paid to the influence of the size of the catchment and the event probability on the relative contribution of a single event to the total loads transported in the river. Further, the development of phosphorus loads along the Danube River at a flood event is shown. From the results it can be concluded that there is no immediate influence of high flow and flood events in upstream parts of the Basin on the transport of phosphorus from the catchment to the receiving Sea. Particle-bound phosphorus is mobilised from the catchment (through erosion) and the river bottom to a high extent at high flow events and transported at peak discharges to downstream, where retention by sedimentation of particles takes place. On the one hand this retention is a transport to flooded areas. In this case it can be considered as more or less long term retention. On the other hand sedimentation takes place in the riverbed, in case the tractive effort of the river is reduced. In this second case the P-pool in the sediments of the sedimentation area will be increased. If anaerobic conditions in the sediment appear, part of the phosphorus will be transformed to soluble ortho-phosphate and will continuously contribute to the phosphorus transport to the receiving sea. Part of the P-retained in the river sediment will be mobilised by resuspension at the next biggest high flow event. Altogether, these alternating processes of suspension, transport, export to flooded areas or sedimentation in the river bed with partly solution and partly resuspension at the next event decrease the share of the phosphorus transport during high flow events on the total loads transported in the more downstream parts of a catchments as compared to the more upstream parts. In the year of occurrence of an extreme flood event the P-transport of this year is dominated by the flood event. As an average over many years the contribution of high flow events to the total P-transport still may be between 7 and 20% in smaller catchments (around 1,000 km2). In a big catchment (e.g. river Danube) much smaller contributions of flood events on the total P-transport can be expected as an average over many years.

FINE PARTICLE EMISSIONS INFORMATION SYSTEM: SUMMARY REPORT (SUMMER 1976)

EPA Science Inventory

The report summarizes the initial loading of data into the Fine Particle Emissions Information System (FPEIS), a computerized database on primary fine particle emissions to the atmosphere from stationary sources, designed to assist engineers and scientists engaged in fine particl...

Thermoresponsive magnetic composite nanomaterials for multimodal cancer therapy.

PubMed

Purushotham, S; Ramanujan, R V

2010-02-01

The synthesis, characterization and property evaluation of drug-loaded polymer-coated magnetic nanoparticles (MNPs) relevant to multimodal cancer therapy has been studied. The hyperthermia and controlled drug release characteristics of these particles was examined. Magnetite (Fe(3)O(4))-poly-n-(isopropylacrylamide) (PNIPAM) composite MNPs were synthesized in a core-shell morphology by dispersion polymerization of n-(isopropylacrylamide) chains in the presence of a magnetite ferrofluid. These core-shell composite particles, with a core diameter of approximately 13nm, were loaded with the anti-cancer drug doxorubicin (dox), and the resulting composite nanoparticles (CNPs) exhibit thermoresponsive properties. The magnetic properties of the composite particles are close to those of the uncoated magnetic particles. In an alternating magnetic field (AMF), composite particles loaded with 4.15 wt.% dox exhibit excellent heating properties as well as simultaneous drug release. Drug release testing confirmed that release was much higher above the lower critical solution temperature (LCST) of the CNP, with a release of up to 78.1% of bound dox in 29h. Controlled drug release testing of the particles reveals that the thermoresponsive property can act as an on/off switch by blocking drug release below the LCST. Our work suggests that these dox-loaded polymer-coated MNPs show excellent in vitro hyperthermia and drug release behavior, with the ability to release drugs in the presence of AMF, and the potential to act as agents for combined targeting, hyperthermia and controlled drug release treatment of cancer.

Cyclodextrin-based metal-organic frameworks particles as efficient carriers for lansoprazole: Study of morphology and chemical composition of individual particles.

PubMed

Li, Xue; Guo, Tao; Lachmanski, Laurent; Manoli, Francesco; Menendez-Miranda, Mario; Manet, Ilse; Guo, Zhen; Wu, Li; Zhang, Jiwen; Gref, Ruxandra

2017-10-15

Cyclodextrin-based metal-organic frameworks (CD-MOFs) represent an environment-friendly and biocompatible class of MOFs drawing increasing attention in drug delivery. Lansoprazole (LPZ) is a proton-pump inhibitor used to reduce the production of acid in the stomach and recently identified as an antitubercular prodrug. Herein, LPZ loaded CD-MOFs were successfully synthesized upon the assembly with γ-CD in the presence of K + ions using an optimized co-crystallization method. They were characterized in terms of morphology, size and crystallinity, showing almost perfect cubic morphologies with monodispersed size distributions. The crystalline particles, loaded or not with LPZ, have mean diameters of around 6μm. The payloads reached 23.2±2.1% (wt) which corresponds to a molar ratio of 1:1 between LPZ and γ-CD. It was demonstrated that even after two years storage, the incorporated drug inside the CD-MOFs maintained its spectroscopic characteristics. Molecular modelling provided a deeper insight into the interaction between the LPZ and CD-MOFs. Raman spectra of individual particles were recorded, confirming the formation of inclusion complexes within the tridimensional CD-MOF structures. Of note, it was found that each individual particle had the same chemical composition. The LPZ-loaded particles had remarkable homogeneity in terms of both drug loading and size. These results pave the way towards the use of CD-MOFs for drug delivery purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Spray-dried casein-based micelles as a vehicle for solubilization and controlled delivery of flutamide: formulation, characterization, and in vivo pharmacokinetics.

PubMed

Elzoghby, Ahmed O; Helmy, Maged W; Samy, Wael M; Elgindy, Nazik A

2013-08-01

Novel casein (CAS)-based micelles loaded with the poorly soluble anti-cancer drug, flutamide (FLT), were successfully developed in a powdered form via spray-drying technique. Genipin (GNP) was used to crosslink CAS micelles as demonstrated by color variation of the micelles. Drug solubilization was enhanced by incorporation within the hydrophobic micellar core which was confirmed by solubility study and UV spectra. Spherical core-shell micelles were obtained with a particle size below 100 nm and zeta potential around -30 mV. At low drug loading, FLT was totally incorporated within micellar core as revealed by thermal analysis. However, at higher loading, excess non-incorporated drug at micelle surface caused a significant reduction in the surface charge density. Turbidity measurements demonstrated the high physical stability of micelles for 2 weeks dependent on GNP-crosslinking degree. In a dry powdered form, the micelles were stable for 6 months with no significant changes in drug content or particle size. A sustained drug release from CAS micelles up to 5 days was observed. After i.v. administration into rats, CAS micelles exhibited a prolonged plasma circulation of FLT compared to drug solution. Furthermore, a more prolonged drug systemic circulation was observed for GNP-crosslinked micelles. Overall, this study reports the application of spray-dried natural protein-based micelles for i.v. delivery of hydrophobic anti-cancer drugs such as FLT. Copyright © 2013 Elsevier B.V. All rights reserved.

Dilation and breakage dissipation of granular soils subjected to monotonic loading

NASA Astrophysics Data System (ADS)

Sun, Yifei; Xiao, Yang; Ji, Hua

2016-12-01

Dilation and breakage energy dissipation of four different granular soils are investigated by using an energy balance equation. Due to particle breakage, the dilation curve does not necessarily pass through the origin of coordinates. Breakage energy dissipation is found to increase significantly at the initial loading stage and then gradually become stabilised. The incremental dissipation ratio between breakage energy and plastic work exhibits almost independence of the confining pressure. Accordingly, a plastic flow rule considering the effect of particle breakage is suggested. The critical state friction angle is found to be a combination of the basic friction between particles and the friction contributed by particle breakage.

Probability distributions of bed load particle velocities, accelerations, hop distances, and travel times informed by Jaynes's principle of maximum entropy

USGS Publications Warehouse

Furbish, David; Schmeeckle, Mark; Schumer, Rina; Fathel, Siobhan

2016-01-01

We describe the most likely forms of the probability distributions of bed load particle velocities, accelerations, hop distances, and travel times, in a manner that formally appeals to inferential statistics while honoring mechanical and kinematic constraints imposed by equilibrium transport conditions. The analysis is based on E. Jaynes's elaboration of the implications of the similarity between the Gibbs entropy in statistical mechanics and the Shannon entropy in information theory. By maximizing the information entropy of a distribution subject to known constraints on its moments, our choice of the form of the distribution is unbiased. The analysis suggests that particle velocities and travel times are exponentially distributed and that particle accelerations follow a Laplace distribution with zero mean. Particle hop distances, viewed alone, ought to be distributed exponentially. However, the covariance between hop distances and travel times precludes this result. Instead, the covariance structure suggests that hop distances follow a Weibull distribution. These distributions are consistent with high-resolution measurements obtained from high-speed imaging of bed load particle motions. The analysis brings us closer to choosing distributions based on our mechanical insight.

Phosphorescence Kinetics of Singlet Oxygen Produced by Photosensitization in Spherical Nanoparticles. Part II. The Case of Hypericin-Loaded Low-Density Lipoprotein Particles.

PubMed

Datta, Shubhashis; Hovan, Andrej; Jutková, Annamária; Kruglik, Sergei G; Jancura, Daniel; Miskovsky, Pavol; Bánó, Gregor

2018-05-24

The phosphorescence kinetics of singlet oxygen produced by photosensitized hypericin (Hyp) molecules inside low-density lipoprotein (LDL) particles was studied experimentally and by means of numerical and analytical modeling. The phosphorescence signal was measured after short laser pulse irradiation of aqueous Hyp/LDL solutions. The Hyp triplet state lifetime determined by a laser flash-photolysis measurement was 5.3 × 10 -6 s. The numerical and the analytical model described in part I of the present work (DOI: 10.1021/acs.jpcb.8b00658) were used to analyze the observed phosphorescence kinetics of singlet oxygen. It was shown that singlet oxygen diffuses out of LDL particles on a time scale shorter than 0.1 μs. The total (integrated) concentration of singlet oxygen inside LDL is more than an order of magnitude smaller than the total singlet oxygen concentration in the solvent. The time course of singlet oxygen concentrations inside and outside the particles was calculated using simplified representations of the LDL internal structure. The experimental phosphorescence data were fitted by a linear combination of these concentrations using the emission factor E (the ratio of the radiative singlet oxygen depopulation rate constants inside and outside LDL) as a fitting parameter. The emission factor was determined to be E = 6.7 ± 2.5. Control measurements were carried out by adding sodium azide, a strong singlet oxygen quencher, to the solution.

Meso-scopic Densification in Brittle Granular Materials

NASA Astrophysics Data System (ADS)

Neal, William; Appleby-Thomas, Gareth; Collins, Gareth

2013-06-01

Particulate materials are ideally suited to shock absorbing applications due to the large amounts of energy required to deform their inherently complex meso-structure. Significant effort is being made to improve macro-scale material models to represent these atypical materials. On the long road towards achieving this capability, an important milestone would be to understand how particle densification mechanisms are affected by loading rate. In brittle particulate materials, the majority of densification is caused by particle fracture. Macro-scale quasi-static and dynamic compaction curves have been measured that show good qualitative agreement. There are, however, some differences that appear to be dependent on the loading rate that require further investigation. This study aims to investigate the difference in grain-fracture behavior between the quasi-static and shock loading response of brittle glass microsphere beds using a combination of quasi-static and dynamic loading techniques. Results from pressure-density measurements, sample recovery, and meso-scale hydrocode models (iSALE, an in-house simulation package) are discussed to explain the differences in particle densification mechanisms between the two loading rate regimes. Gratefully funded by AWE.plc.

Spall damage of a Ta particle-reinforced metallic glass matrix composite under high strain rate loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, X. C.; Jian, W. R.; Huang, J. Y.

We investigate deformation and damage of a Zr-based bulk metallic glass (BMG) and its Ta particle-reinforced composite (MGMC) under impact loading, as well as quasi-static tension for comparison. Yield strength, spall strength, and damage accumulation rate are obtained from free-surface velocity histories, and MGMC appears to be more damage-resistant. Scanning electron microscopy, electron back scattering diffraction and x-ray computed tomography, are utilized for characterizing microstructures, which show features consistent with macroscopic measurements. Different damage and fracture modes are observed for BMG and MGMC. Multiple well-defined spall planes are observed in BMG, while isolated and scattered cracking around reinforced particles dominatesmore » fracture of MGMC. Particle–matrix interface serves as the source and barrier to crack nucleation and propagation under both quasi-static and impact loading. Finally, deformation twinning and grain refinement play a key role in plastic deformation during shock loading but not in quasi-static loading. In addition, 3D cup-cone structures are resolved in BMG, but not in MGMC due to its heterogeneous stress field.« less

Spall damage of a Ta particle-reinforced metallic glass matrix composite under high strain rate loading

DOE PAGES

Tang, X. C.; Jian, W. R.; Huang, J. Y.; ...

2017-11-11

We investigate deformation and damage of a Zr-based bulk metallic glass (BMG) and its Ta particle-reinforced composite (MGMC) under impact loading, as well as quasi-static tension for comparison. Yield strength, spall strength, and damage accumulation rate are obtained from free-surface velocity histories, and MGMC appears to be more damage-resistant. Scanning electron microscopy, electron back scattering diffraction and x-ray computed tomography, are utilized for characterizing microstructures, which show features consistent with macroscopic measurements. Different damage and fracture modes are observed for BMG and MGMC. Multiple well-defined spall planes are observed in BMG, while isolated and scattered cracking around reinforced particles dominatesmore » fracture of MGMC. Particle–matrix interface serves as the source and barrier to crack nucleation and propagation under both quasi-static and impact loading. Finally, deformation twinning and grain refinement play a key role in plastic deformation during shock loading but not in quasi-static loading. In addition, 3D cup-cone structures are resolved in BMG, but not in MGMC due to its heterogeneous stress field.« less

Nanostructured Lipid Carriers Loaded with Baicalin: An Efficient Carrier for Enhanced Antidiabetic Effects

PubMed Central

Shi, Feng; Wei, Zheng; Zhao, Yingying; Xu, Ximing

2016-01-01

Context: Recent studies have demonstrated that baicalin has antihyperglycemic effects by inhibiting lipid peroxidation. Baicalin is low hydrophilic and poorly absorbed after oral administration. Thus, a suitable formulation is highly desired to overcome the disadvantages of baicalin. Objective: The objective of this work was to prepare baicalin-loaded nanostructured lipid carriers (B-NLCs) for enhanced antidiabetic effects. Materials and Methods: B-NLCs were prepared by high-pressure homogenization method using Precirol as the solid lipid and Miglyol as the liquid lipid. The properties of the NLCs, such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE), were investigated. The morphology of NLCs was observed by transmission electron microscopy. In addition, drug release and antidiabetic activity were also studied. Results: The results revealed that B-NLCs particles were uniformly in the nanosize range and of spherical morphology with a mean size of 92 ± 3.1 nm, a ZP of −31.35 ± 3.08 mV, and an EE of 85.29 ± 3.42%. Baicalin was released from NLCs in a sustained manner. In addition, B-NLCs showed a significantly higher antidiabetic efficacy compared with baicalin. Conclusion: B-NLCs described in this study are well-suited for the delivery of baicalin. SUMMARY Currently, herbal medicines have attracted increasing attention as a complementary approach for type 2 diabetesBaicalin has antihyperglycemic effects by inhibiting lipid peroxidationA suitable formulation is highly desired to overcome the disadvantages (poor solubility and low bioavailability) of baicalinNanostructured lipid carriers could enhance the antidiabetic effects of baicalin. Abbreviations used: B-NLCs: Baicalin-Loaded Nanostructured Lipid Carriers, B-SUS: Baicalin Water Suspension, EE: Encapsulation Efficiency, FBG: Fasting Blood Glucose, HbAlc: Glycosylated Hemoglobin, HPLC: High-performance Liquid Chromatography; NLCs: Nanostructured Lipid Carriers, PI: Polydispersity Index, SD: Sprague-Dawley, SLNs: Solid lipid nanoparticles, STZ: Streptozotocin, TC: Total cholesterol, TEM: Transmission Electron Microscope, TG: Total Triglyceride, ZP: Zeta Potential. PMID:27601850

Nanostructured Lipid Carriers Loaded with Baicalin: An Efficient Carrier for Enhanced Antidiabetic Effects.

PubMed

Shi, Feng; Wei, Zheng; Zhao, Yingying; Xu, Ximing

2016-01-01

Recent studies have demonstrated that baicalin has antihyperglycemic effects by inhibiting lipid peroxidation. Baicalin is low hydrophilic and poorly absorbed after oral administration. Thus, a suitable formulation is highly desired to overcome the disadvantages of baicalin. The objective of this work was to prepare baicalin-loaded nanostructured lipid carriers (B-NLCs) for enhanced antidiabetic effects. B-NLCs were prepared by high-pressure homogenization method using Precirol as the solid lipid and Miglyol as the liquid lipid. The properties of the NLCs, such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE), were investigated. The morphology of NLCs was observed by transmission electron microscopy. In addition, drug release and antidiabetic activity were also studied. The results revealed that B-NLCs particles were uniformly in the nanosize range and of spherical morphology with a mean size of 92 ± 3.1 nm, a ZP of -31.35 ± 3.08 mV, and an EE of 85.29 ± 3.42%. Baicalin was released from NLCs in a sustained manner. In addition, B-NLCs showed a significantly higher antidiabetic efficacy compared with baicalin. B-NLCs described in this study are well-suited for the delivery of baicalin. Currently, herbal medicines have attracted increasing attention as a complementary approach for type 2 diabetesBaicalin has antihyperglycemic effects by inhibiting lipid peroxidationA suitable formulation is highly desired to overcome the disadvantages (poor solubility and low bioavailability) of baicalinNanostructured lipid carriers could enhance the antidiabetic effects of baicalin. Abbreviations used: B-NLCs: Baicalin-Loaded Nanostructured Lipid Carriers, B-SUS: Baicalin Water Suspension, EE: Encapsulation Efficiency, FBG: Fasting Blood Glucose, HbAlc: Glycosylated Hemoglobin, HPLC: High-performance Liquid Chromatography; NLCs: Nanostructured Lipid Carriers, PI: Polydispersity Index, SD: Sprague-Dawley, SLNs: Solid lipid nanoparticles, STZ: Streptozotocin, TC: Total cholesterol, TEM: Transmission Electron Microscope, TG: Total Triglyceride, ZP: Zeta Potential.

Long-range transport of airborne microbes over the global tropical and subtropical ocean.

PubMed

Mayol, Eva; Arrieta, Jesús M; Jiménez, Maria A; Martínez-Asensio, Adrián; Garcias-Bonet, Neus; Dachs, Jordi; González-Gaya, Belén; Royer, Sarah-J; Benítez-Barrios, Verónica M; Fraile-Nuez, Eugenio; Duarte, Carlos M

2017-08-04

The atmosphere plays a fundamental role in the transport of microbes across the planet but it is often neglected as a microbial habitat. Although the ocean represents two thirds of the Earth's surface, there is little information on the atmospheric microbial load over the open ocean. Here we provide a global estimate of microbial loads and air-sea exchanges over the tropical and subtropical oceans based on the data collected along the Malaspina 2010 Circumnavigation Expedition. Total loads of airborne prokaryotes and eukaryotes were estimated at 2.2 × 10 21 and 2.1 × 10 21 cells, respectively. Overall 33-68% of these microorganisms could be traced to a marine origin, being transported thousands of kilometres before re-entering the ocean. Moreover, our results show a substantial load of terrestrial microbes transported over the oceans, with abundances declining exponentially with distance from land and indicate that islands may act as stepping stones facilitating the transoceanic transport of terrestrial microbes.The extent to which the ocean acts as a sink and source of airborne particles to the atmosphere is unresolved. Here, the authors report high microbial loads over the tropical Atlantic, Pacific and Indian oceans and propose islands as stepping stones for the transoceanic transport of terrestrial microbes..

Bio-Functional, Lanthanide-Labeled Polymer Particles by Seeded Emulsion Polymerization and their Characterization by Novel ICP-MS Detection.

PubMed

Thickett, Stuart C; Abdelrahman, Ahmed I; Ornatsky, Olga; Bandura, Dmitry; Baranov, Vladimir; Winnik, Mitchell A

2010-01-01

We present the synthesis and characterization of monodisperse, sub-micron poly(styrene) (PS) particles loaded with up to and including 10(7) lanthanide (Ln) ions per particle. These particles have been synthesized by seeded emulsion polymerization with a mixture of monomer and a pre-formed Ln complex, and analyzed on a particle-by-particle basis by a unique inductively coupled plasma mass cytometer. Seed particles were prepared by surfactant-free emulsion polymerization (SFEP) to obtain large particle sizes in aqueous media. Extensive surface acid functionality was introduced using the acid-functional initiator ACVA, either during seed latex synthesis or in the second stage of polymerization. The loading of particles with three different Ln ions (Eu, Tb, and Ho) has proven to be close to 100 % efficient on an individual and combined basis. Covalent attachment of metal-tagged peptides and proteins such as Neutravidin to the particle surface was shown to be successful and the number of bound species can be readily determined. We believe these particles can serve as precursors for multiplexed, bead-based bio-assays utilizing mass cytometric detection.

Bio-Functional, Lanthanide-Labeled Polymer Particles by Seeded Emulsion Polymerization and their Characterization by Novel ICP-MS Detection

PubMed Central

Thickett, Stuart C.; Abdelrahman, Ahmed I.; Ornatsky, Olga; Bandura, Dmitry; Baranov, Vladimir; Winnik, Mitchell A.

2010-01-01

We present the synthesis and characterization of monodisperse, sub-micron poly(styrene) (PS) particles loaded with up to and including 107 lanthanide (Ln) ions per particle. These particles have been synthesized by seeded emulsion polymerization with a mixture of monomer and a pre-formed Ln complex, and analyzed on a particle-by-particle basis by a unique inductively coupled plasma mass cytometer. Seed particles were prepared by surfactant-free emulsion polymerization (SFEP) to obtain large particle sizes in aqueous media. Extensive surface acid functionality was introduced using the acid-functional initiator ACVA, either during seed latex synthesis or in the second stage of polymerization. The loading of particles with three different Ln ions (Eu, Tb, and Ho) has proven to be close to 100 % efficient on an individual and combined basis. Covalent attachment of metal-tagged peptides and proteins such as Neutravidin to the particle surface was shown to be successful and the number of bound species can be readily determined. We believe these particles can serve as precursors for multiplexed, bead-based bio-assays utilizing mass cytometric detection. PMID:20396648

Mobile Particulate Emission Studies of New York City Vehicles

NASA Astrophysics Data System (ADS)

Canagaratna, M.; Jayne, J.; Shi, Q.; Kolb, C. E.; Worsnop, D.

Emissions from both diesel and gasoline powered motor vehicles are a significant source of urban particulate (PM2.5) and trace gas pollution. Emission characteriza- tions of motor vehicles are typically performed using a dynamometer. Few studies have been performed which characterize emissions from in-use vehicles using a mo- bile sampling platform. This work, which was part of the PM2.5 Technology Assess- ment and Characterization Study in New York (PMTACS-NY), describes the applica- tion of new instrumentation for rapid (1-5 second) and real-time characterization of particulate emissions from in-use vehicles . An Aerosol Mass Spectrometer (AMS) was deployed on the Aerodyne Research (ARI) mobile laboratory designed to "chase" target vehicles in and around the New York City area and measure their emissions under actual driving conditions. The AMS provides quantitative particle size and composition information for volatile and semi- volatile matter (0.05-2.5 um). The AMS was operated in a fast acquisition mode de- signed to monitor particle emissions from the mobile sources. In this mode mass spec- tra (0-300 amu) and chemically speciated particle size distributions were recorded at 4 sec intervals. In addition to the AMS, the Mobile Laboratory was equipped with the ARI tunable diode laser (TILDAS) system which was configured to measure NO, NO2, CO, CH4, SO2 and formaldehyde, a global positioning system, a condensation particle counter, and a Licor CO2 instrument. The simultaneous measurement of particulate mass loading and plume CO2 enabled the calculation of emission indices for the targeted vehicles. Particulate matter emis- sion indices for a representative fraction of the NYC Metropolitan Transit Authority (MTA) bus fleet were determined in an effort to characterize new emission control technologies currently implemented by the NYC MTA. In addition to total particle emission indices, chemically speciated sulfate and organic mass loadings and size distributions were determined. Representative mass spectral signatures and size dis- tributions observed from the exhaust plume particles and correlations between the simultaneous gas and particulate measurements will be discussed. Differences in ob- served particle emission factors and compositions between buses using different fuels and technologies will also be presented.

Analyses of Fatigue and Fatigue-Crack Growth under Constant- and Variable-Amplitude Loading

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1999-01-01

Studies on the growth of small cracks have led to the observation that fatigue life of many engineering materials is primarily crack growth from micro-structural features, such as inclusion particles, voids, slip-bands or from manufacturing defects. This paper reviews the capabilities of a plasticity-induced crack-closure model to predict fatigue lives of metallic materials using small-crack theory under various loading conditions. Constraint factors, to account for three-dimensional effects, were selected to correlate large-crack growth rate data as a function of the effective stress-intensity factor range (delta K(sub eff)) under constant-amplitude loading. Modifications to the delta K(sub eff)-rate relations in the near-threshold regime were needed to fit measured small-crack growth rate behavior. The model was then used to calculate small- and large-crack growth rates, and to predict total fatigue lives, for notched and un-notched specimens under constant-amplitude and spectrum loading. Fatigue lives were predicted using crack-growth relations and micro-structural features like those that initiated cracks in the fatigue specimens for most of the materials analyzed. Results from the tests and analyses agreed well.

Energy and operation management of a microgrid using particle swarm optimization

NASA Astrophysics Data System (ADS)

Radosavljević, Jordan; Jevtić, Miroljub; Klimenta, Dardan

2016-05-01

This article presents an efficient algorithm based on particle swarm optimization (PSO) for energy and operation management (EOM) of a microgrid including different distributed generation units and energy storage devices. The proposed approach employs PSO to minimize the total energy and operating cost of the microgrid via optimal adjustment of the control variables of the EOM, while satisfying various operating constraints. Owing to the stochastic nature of energy produced from renewable sources, i.e. wind turbines and photovoltaic systems, as well as load uncertainties and market prices, a probabilistic approach in the EOM is introduced. The proposed method is examined and tested on a typical grid-connected microgrid including fuel cell, gas-fired microturbine, wind turbine, photovoltaic and energy storage devices. The obtained results prove the efficiency of the proposed approach to solve the EOM of the microgrids.

External Catalyst Breakup Phenomena

DTIC Science & Technology

1976-06-01

catalyst particle can cause high internal pressures which result in particle destruction. Analytical results suggest rhat erosion effects from solid...mechanisms. * Pressure Forces. High G loadings and bed pressure drops should be avoided. Bed pre-loads should be kept at a minimum value. Thruster...5.2.7.1 Failure Theories ............................ 243 5.2.7.2 Maximum Tension Stress Criterion ............ 244 5.2.7.3 Distortion Energy Approach

A comparison of additional treatment processes to limit particle accumulation and microbial growth during drinking water distribution.

PubMed

Liu, G; Lut, M C; Verberk, J Q J C; Van Dijk, J C

2013-05-15

Water quality changes, particle accumulation and microbial growth occurring in pilot-scale water distribution systems fed with normally treated and additional treated groundwater were monitored over a period of almost one year. The treatment processes were ranked in the following order: nanofiltration (NF) > (better than) ultrafiltration (UF) > ion exchange (IEX) for limiting particle accumulation. A different order was found for limiting overall microbial growth: NF > IEX > UF. There were strong correlations between particle load and particle accumulation, and between nutrient load and microbial growth. It was concluded that particle accumulation can be controlled by reducing the particle load in water treatment plants; and the microbial growth can be better controlled by limiting organic nutrients rather than removing biomass in water treatment plants. The major focus of this study was on microbial growth. The results demonstrated that growth occurred in all types of treated water, including the phases of bulk water, biofilm and loose deposits. Considering the growth in different phases, similar growth in bulk water was observed for all treatments; NF strongly reduced growth both in loose deposits and in biofilm; UF promoted growth in biofilm, while strongly limiting growth in loose deposits. IEX had good efficiency in between UF and NF, limiting both growths in loose deposits and in biofilm. Significant growth was found in loose deposits, suggesting that loose deposit biomass should be taken into account for growth evaluation and/or prediction. Strong correlations were found between microbial growth and pressure drop in a membrane fouling simulator which proved that a membrane fouling simulator can be a fast growth predictor (within a week). Different results obtained by adenosine triphosphate and flow cytometry cell counts revealed that ATP can accurately describe both suspended and particle-associated biomass, and flow cytometry files of TCC measurements needs to be further processed for particle loaded samples and/or a pretreatment protocol should be developed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Establishment and clinical applications of a portable system for capturing influenza viruses released through coughing.

PubMed

Hatagishi, Etsuko; Okamoto, Michiko; Ohmiya, Suguru; Yano, Hisakazu; Hori, Toru; Saito, Wakana; Miki, Hiroshi; Suzuki, Yasushi; Saito, Reiko; Yamamoto, Taro; Shoji, Makoto; Morisaki, Yoshihisa; Sakata, Soichiro; Nishimura, Hidekazu

2014-01-01

Coughing plays an important role in influenza transmission; however, there is insufficient information regarding the viral load in cough because of the lack of convenient and reliable collection methods. We developed a portable airborne particle-collection system to measure the viral load; it is equipped with an air sampler to draw air and pass it through a gelatin membrane filter connected to a cone-shaped, megaphone-like device to guide the cough airflow to the membrane. The membrane was dissolved in a medium, and the viral load was measured using quantitative real-time reverse transcriptase-polymerase chain reaction and a plaque assay. The approximate viral recovery rate of this system was 10% in simulation experiments to collect and quantify the viral particles aerosolized by a nebulizer. Using this system, cough samples were collected from 56 influenza A patients. The total viral detection rate was 41% (23/56), and the viral loads varied significantly (from <10, less than the detection limit, to 2240 viral gene copies/cough). Viable viruses were detected from 3 samples with ≤18 plaque forming units per cough sample. The virus detection rates were similar among different groups of patients infected with different viral subtypes and during different influenza seasons. Among patients who did not receive antiviral treatment, viruses were detected in one of six cases in the vaccinated group and four of six cases in the unvaccinated group. We found cases with high viral titers in throat swabs or oral secretions but very low or undetectable in coughs and vice versa suggesting other possible anatomical sites where the viruses might be mixed into the cough. Our system is easy to operate, appropriate for bedside use, and is useful for comparing the viral load in cough samples from influenza patients under various conditions and settings. However, further large-scale studies are warranted to validate our results.

Source apportionment of particulate pollutants in the atmosphere over the Northern Yellow Sea

NASA Astrophysics Data System (ADS)

Wang, L.; Qi, J. H.; Shi, J. H.; Chen, X. J.; Gao, H. W.

2013-05-01

Atmospheric aerosol samples were collected over the Northern Yellow Sea of China during the years of 2006 and 2007, in which the Total Carbon (TC), Cu, Pb, Cd, V, Zn, Fe, Al, Na+, Ca2+, Mg2+, NH4+, NO3-, SO42-, Cl-, and K+ were measured. The principle components analysis (PCA) and positive matrix factorization (PMF) receptor models were used to identify the sources of particulate matter. The results indicated that seven factors contributed to the atmospheric particles over the Northern Yellow Sea, i.e., two secondary aerosols (sulfate and nitrate), soil dust, biomass burning, oil combustion, sea salt, and metal smelting. When the whole database was considered, secondary aerosol formation contributed the most to the atmospheric particle content, followed by soil dust. Secondary aerosols and soil dust consisted of 65.65% of the total mass of particulate matter. The results also suggested that the aerosols over the North Yellow Sea were heavily influenced by ship emission over the local sea area and by continental agricultural activities in the northern China, indicating by high loading of V in oil combustion and high loading of K+ in biomass burning. However, the contribution of each factor varied greatly over the different seasons. In spring and autumn, soil dust and biomass burning were the dominant factors. In summer, heavy oil combustion contributed the most among these factors. In winter, secondary aerosols were major sources. Backward trajectories analysis indicated the 66% of air mass in summer was from the ocean, while the air mass is mainly from the continent in other seasons.

Engine-Operating Load Influences Diesel Exhaust Composition and Cardiopulmonary and Immune Responses

PubMed Central

Campen, Matthew J.; Harrod, Kevin S.; Seagrave, JeanClare; Seilkop, Steven K.; Mauderly, Joe L.

2011-01-01

Background: The composition of diesel engine exhaust (DEE) varies by engine type and condition, fuel, engine operation, and exhaust after treatment such as particle traps. DEE has been shown to increase inflammation, susceptibility to infection, and cardiovascular responses in experimentally exposed rodents and humans. Engines used in these studies have been operated at idle, at different steady-state loads, or on variable-load cycles, but exposures are often reported only as the mass concentration of particulate matter (PM), and the effects of different engine loads and the resulting differences in DEE composition are unknown. Objectives: We assessed the impacts of load-related differences in DEE composition on models of inflammation, susceptibility to infection, and cardiovascular toxicity. Methods: We assessed inflammation and susceptibility to viral infection in C57BL/6 mice and cardiovascular toxicity in APOE–/– mice after being exposed to DEE generated from a single-cylinder diesel generator operated at partial or full load. Results: At the same PM mass concentration, partial load resulted in higher proportions of particle organic carbon content and a smaller particle size than did high load. Vapor-phase hydrocarbon content was greater at partial load. Compared with high-load DEE, partial-load DEE caused greater responses in heart rate and T-wave morphology, in terms of both magnitude and rapidity of onset of effects, consistent with previous findings that systemic effects may be driven largely by the gas phase of the exposure atmospheres. However, high-load DEE caused more lung inflammation and greater susceptibility to viral infection than did partial load. Conclusions: Differences in engine load, as well as other operating variables, are important determinants of the type and magnitude of responses to inhaled DEE. PM mass concentration alone is not a sufficient basis for comparing or combining results from studies using DEE generated under different conditions. PMID:21524982

Phosphorus loads from different urban storm runoff sources in southern China: a case study in Wenzhou City.

PubMed

Zhou, Dong; Bi, Chun-Juan; Chen, Zhen-Lou; Yu, Zhong-Jie; Wang, Jun; Han, Jing-Chao

2013-11-01

Storm runoff from six types of underlying surface area during five rainfall events in two urban study areas of Wenzhou City, China was investigated to measure phosphorus (P) concentrations and discharge rates. The average event mean concentrations (EMCs) of total phosphorus (TP), total dissolved phosphorus (TDP), and particulate phosphorus (PP) ranged from 0.02 to 2.5 mg · L(-1), 0.01 to 0.48 mg · L(-1), and 0.02 to 2.43 mg · L(-1), respectively. PP was generally the dominant component of TP in storm runoff, while the major form of P varied over time, especially in roof runoff, where TDP made up the largest portion in the latter stages of runoff events. Both TP and PP concentrations were positively correlated with pH, total suspended solids (TSS), and biochemical oxygen demand (BOD)/chemical oxygen demand (COD) concentrations (p<0.01), while TDP was positively correlated with BOD/COD only (p<0.01). In addition, the EMCs of TP and PP were negatively correlated with maximum rainfall intensity (p<0.05), while the EMCs of TDP positively correlated with the antecedent dry weather period (p<0.05). The annual TP emission fluxes from the two study areas were 367.33 and 237.85 kg, respectively. Underlying surface type determined the TP and PP loadings in storm runoff, but regional environmental conditions affected the export of TDP more significantly. Our results indicate that the removal of particles from storm runoff could be an effective measure to attenuate P loadings to receiving water bodies.

Methotrexate Nanoparticles Prepared with Codendrimer from Polyamidoamine (PAMAM) and Oligoethylene Glycols (OEG) Dendrons: Antitumor Efficacy in Vitro and in Vivo

NASA Astrophysics Data System (ADS)

Zhao, Yanna; Guo, Yifei; Li, Ran; Wang, Ting; Han, Meihua; Zhu, Chunyan; Wang, Xiangtao

2016-07-01

The novel methotrexate-loaded nanoparticles (MTX/PGD NPs) prepared with amphiphilic codendrimer PGD from polyamidoamine and oligothylene glycol dendrons were obtained via antisolvent precipitation method augmented by ultrasonication. Based on the excellent hydrophility of PGD, the drug-loaded nanoparticles could be investigated easily with the high drug-loading content (~85.2%, w/w). The MTX/PGD NPs possessed spherical morphology, nanoscaled particle size (approximately 182.4 nm), and narrow particle size distribution. Release of MTX from MTX/PGD NPs showed a sustained release manner and completed within 48 h. Hemolytic evaluation indicated MTX/PGD NPs presented good blood compatibility, and the cytotoxicity of nanoparticles against breast cancer cells in vitro, biodistribution in tumor tissue, and antitumor efficacy in vivo were enhanced significantly compared to MTX injection. According to the higher drug-loading content, enhanced antitumor efficacy, and appropriate particle size, MTX/PGD NPs as the drug delivery systems could have potential application for cancer chemotherapy in clinic.

Methotrexate Nanoparticles Prepared with Codendrimer from Polyamidoamine (PAMAM) and Oligoethylene Glycols (OEG) Dendrons: Antitumor Efficacy in Vitro and in Vivo

PubMed Central

Zhao, Yanna; Guo, Yifei; Li, Ran; Wang, Ting; Han, Meihua; Zhu, Chunyan; Wang, Xiangtao

2016-01-01

The novel methotrexate-loaded nanoparticles (MTX/PGD NPs) prepared with amphiphilic codendrimer PGD from polyamidoamine and oligothylene glycol dendrons were obtained via antisolvent precipitation method augmented by ultrasonication. Based on the excellent hydrophility of PGD, the drug-loaded nanoparticles could be investigated easily with the high drug-loading content (~85.2%, w/w). The MTX/PGD NPs possessed spherical morphology, nanoscaled particle size (approximately 182.4 nm), and narrow particle size distribution. Release of MTX from MTX/PGD NPs showed a sustained release manner and completed within 48 h. Hemolytic evaluation indicated MTX/PGD NPs presented good blood compatibility, and the cytotoxicity of nanoparticles against breast cancer cells in vitro, biodistribution in tumor tissue, and antitumor efficacy in vivo were enhanced significantly compared to MTX injection. According to the higher drug-loading content, enhanced antitumor efficacy, and appropriate particle size, MTX/PGD NPs as the drug delivery systems could have potential application for cancer chemotherapy in clinic. PMID:27388443

Turbulent Mixing and Afterburn in Post-Detonation Flow with Dense Particle Clouds

NASA Astrophysics Data System (ADS)

Menon, Suresh

2015-06-01

Reactive metal particles are used as additives in most explosives to enhance afterburn and augment the impact of the explosive. The afterburn is highly dependent on the particle dispersal and mixing in the post-detonation flow. The post-detonation flow is generally characterized by hydrodynamic instabilities emanating from the interaction of the blast waves with the detonation product gases and the ambient air. Further, influenced by the particles, the flow evolves and develops turbulent structures, which play vital role in determining mixing and combustion. Past studies in the field in open literature are reviewed along with some recent studies conducted using three dimensional numerical simulations of particle dispersal and combustion in the post-detonation flow. Spherical nitromethane charges enveloped by particle shells of varying thickness are considered along with dense loading effects. In dense flows, the particles block the flow of the gases and therefore, the role of the inter-particle interactions on particle dispersal cannot be ignored. Thus, both dense and dilute effects must be modeled simultaneously to simulate the post-detonation flow. A hybrid equation of state is employed to study the evolution of flow from detonation initiation till the late time mixing and afterburn. The particle dispersal pattern in each case is compared with the available experimental results. The burn rate and the energy release in each case is quantified and the effect of total mass of the particles and the particle size is analyzed in detail. Strengths and limitations of the various methods used for such studies as well as the uncertainties in the modeling strategies are also highlighted. Supported by Defense Threat Reduction Agency.

PIC simulation of the vacuum power flow for a 5 terawatt, 5 MV, 1 MA pulsed power system

NASA Astrophysics Data System (ADS)

Liu, Laqun; Zou, Wenkang; Liu, Dagang; Guo, Fan; Wang, Huihui; Chen, Lin

2018-03-01

In this paper, a 5 Terawatt, 5 MV, 1 MA pulsed power system based on vacuum magnetic insulation is simulated by the particle-in-cell (PIC) simulation method. The system consists of 50 100-kV linear transformer drive (LTD) cavities in series, using magnetically insulated induction voltage adder (MIVA) technology for pulsed power addition and transmission. The pulsed power formation and the vacuum power flow are simulated when the system works in self-limited flow and load-limited flow. When the pulsed power system isn't connected to the load, the downstream magnetically insulated transmission line (MITL) works in the self-limited flow, the maximum of output current is 1.14 MA and the amplitude of voltage is 4.63 MV. The ratio of the electron current to the total current is 67.5%, when the output current reached the peak value. When the impedance of the load is 3.0 Ω, the downstream MITL works in the self-limited flow, the maximums of output current and the amplitude of voltage are 1.28 MA and 3.96 MV, and the ratio of the electron current to the total current is 11.7% when the output current reached the peak value. In addition, when the switches are triggered in synchronism with the passage of the pulse power flow, it effectively reduces the rise time of the pulse current.

Spatial variability of particle-attached and free-living bacterial diversity in surface waters from the Mackenzie River to the Beaufort Sea (Canadian Arctic)

NASA Astrophysics Data System (ADS)

Ortega-Retuerta, E.; Joux, F.; Jeffrey, W. H.; Ghiglione, J. F.

2013-04-01

We explored the patterns of total and active bacterial community structure in a gradient covering surface waters from the Mackenzie River to the coastal Beaufort Sea in the Canadian Arctic Ocean, with a particular focus on free-living (FL) vs. particle-attached (PA) communities. Capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) showed significant differences when comparing river, coast and open sea bacterial community structures. In contrast to the river and coastal waters, total (16S rDNA-based) and active (16S rRNA-based) communities in the open sea samples were not significantly different, suggesting that most present bacterial groups were equally active in this area. Additionally, we observed significant differences between PA and FL bacterial community structure in the open sea, but similar structure in the two fractions for coastal and river samples. Direct multivariate statistical analyses showed that total community structure was mainly driven by salinity (a proxy of dissolved organic carbon and chromophoric dissolved organic matter), suspended particles, amino acids and chlorophyll a. Pyrosequencing of 16S rRNA genes from selected samples confirmed significant differences between river, coastal and sea samples. The PA fraction was only different (15.7% similarity) from the FL one in the open sea sample. Furthermore, PA samples generally showed higher diversity (Shannon, Simpson and Chao indices) than FL samples. At the class level, Opitutae was most abundant in the PA fraction of the sea sample, followed by Flavobacteria and Gammaproteobacteria, while the FL sea sample was dominated by Alphaproteobacteria. Finally, for the coast and river samples and both PA and FL fractions, Betaproteobacteria, Alphaproteobacteria and Actinobacteria were dominant. These results highlight the coexistence of particle specialists and generalists and the role of particle quality in structuring bacterial communities in the area. These results may also serve as a basis to predict further changes in bacterial communities should climate change lead to further increases in river discharge and related particle loads.

Size and composition distributions of particulate matter emissions: part 2--heavy-duty diesel vehicles.

PubMed

Robert, Michael A; Kleeman, Michael J; Jakober, Christopher A

2007-12-01

Particulate matter (PM) emissions from heavy-duty diesel vehicles (HDDVs) were collected using a chassis dynamometer/dilution sampling system that employed filter-based samplers, cascade impactors, and scanning mobility particle size (SMPS) measurements. Four diesel vehicles with different engine and emission control technologies were tested using the California Air Resources Board Heavy Heavy-Duty Diesel Truck (HHDDT) 5 mode driving cycle. Vehicles were tested using a simulated inertial weight of either 56,000 or 66,000 lb. Exhaust particles were then analyzed for total carbon, elemental carbon (EC), organic matter (OM), and water-soluble ions. HDDV fine (< or =1.8 microm aerodynamic diameter; PM1.8) and ultrafine (0.056-0.1 microm aerodynamic diameter; PM0.1) PM emission rates ranged from 181-581 mg/km and 25-72 mg/km, respectively, with the highest emission rates in both size fractions associated with the oldest vehicle tested. Older diesel vehicles produced fine and ultrafine exhaust particles with higher EC/OM ratios than newer vehicles. Transient modes produced very high EC/OM ratios whereas idle and creep modes produced very low EC/OM ratios. Calcium was the most abundant water-soluble ion with smaller amounts of magnesium, sodium, ammonium ion, and sulfate also detected. Particle mass distributions emitted during the full 5-mode HDDV tests peaked between 100-180 nm and their shapes were not a function of vehicle age. In contrast, particle mass distributions emitted during the idle and creep driving modes from the newest diesel vehicle had a peak diameter of approximately 70 nm, whereas mass distributions emitted from older vehicles had a peak diameter larger than 100 nm for both the idle and creep modes. Increasing inertial loads reduced the OM emissions, causing the residual EC emissions to shift to smaller sizes. The same HDDV tested at 56,000 and 66,000 lb had higher PM0.1 EC emissions (+22%) and lower PM0.1 OM emissions (-38%) at the higher load condition.

Do wastewater treatment plants act as a potential point source of microplastics? Preliminary study in the coastal Gulf of Finland, Baltic Sea.

PubMed

Talvitie, Julia; Heinonen, Mari; Pääkkönen, Jari-Pekka; Vahtera, Emil; Mikola, Anna; Setälä, Outi; Vahala, Riku

2015-01-01

This study on the removal of microplastics during different wastewater treatment unit processes was carried out at Viikinmäki wastewater treatment plant (WWTP). The amount of microplastics in the influent was high, but it decreased significantly during the treatment process. The major part of the fibres were removed already in primary sedimentation whereas synthetic particles settled mostly in secondary sedimentation. Biological filtration further improved the removal. A proportion of the microplastic load also passed the treatment and was found in the effluent, entering the receiving water body. After the treatment process, an average of 4.9 (±1.4) fibres and 8.6 (±2.5) particles were found per litre of wastewater. The total textile fibre concentration in the samples collected from the surface waters in the Helsinki archipelago varied between 0.01 and 0.65 fibres per litre, while the synthetic particle concentration varied between 0.5 and 9.4 particles per litre. The average fibre concentration was 25 times higher and the particle concentration was three times higher in the effluent compared to the receiving body of water. This indicates that WWTPs may operate as a route for microplastics entering the sea.

Measurements of ultrafine particles and other vehicular pollutants inside school buses in South Texas

NASA Astrophysics Data System (ADS)

Zhang, Qunfang; Zhu, Yifang

2010-01-01

Increasing evidence has demonstrated toxic effects of vehicular emitted ultrafine particles (UFPs, diameter < 100 nm), with the highest human exposure usually occurring on and near roadways. Children are particularly at risk due to immature respiratory systems and faster breathing rates. In this study, children's exposure to in-cabin air pollutants, especially UFPs, was measured inside four diesel-powered school buses. Two 1990 and two 2006 model year diesel-powered school buses were selected to represent the age extremes of school buses in service. Each bus was driven on two routine bus runs to study school children's exposure under different transportation conditions in South Texas. The number concentration and size distribution of UFPs, total particle number concentration, PM 2.5, PM 10, black carbon (BC), CO, and CO 2 levels were monitored inside the buses. The average total particle number concentrations observed inside the school buses ranged from 7.3 × 10 3 to 3.4 × 10 4 particles cm -3, depending on engine age and window position. When the windows were closed, the in-cabin air pollutants were more likely due to the school buses' self-pollution. The 1990 model year school buses demonstrated much higher air pollutant concentrations than the 2006 model year ones. When the windows were open, the majority of in-cabin air pollutants came from the outside roadway environment with similar pollutant levels observed regardless of engine ages. The highest average UFP concentration was observed at a bus transfer station where approximately 27 idling school buses were queued to load or unload students. Starting-up and idling generated higher air pollutant levels than the driving state. Higher in-cabin air pollutant concentrations were observed when more students were on board.

IMAA (Integrated Measurements of Aerosol in Agri valley) campaign: Multi-instrumental observations at the largest European oil/gas pre-treatment plant area

NASA Astrophysics Data System (ADS)

Calvello, Mariarosaria; Caggiano, Rosa; Esposito, Francesco; Lettino, Antonio; Sabia, Serena; Summa, Vito; Pavese, Giulia

2017-11-01

A short-term intensive multi-instrumental measurement campaign (Integrated Measurements of Aerosol in Agri valley - IMAA) was carried out near the largest European oil and gas pre-treatment plant (Centro Olio Val d'Agri - COVA) in a populated area, where, so far, ample characterization of aerosol loading is missing. As such, between the 2 and 17 July in 2013, using a number of instruments analyses were carried out on physical, chemical, morphological and optical properties of aerosol at this distinctive site, at both ground and over the atmospheric column, including the investigation of the mixing and transformation of particles. The observation of slag silicates with a rough surface texture is consistent with the presence of oil-related activities which represent the only industrial activity in the area. Desulfurization/sulfur liquefaction processes occurring at COVA can explain the peculiar morphology of calcium-sodium-aluminum particles. The common COVA source was associated with high concentrations of sulfur, nickel and zinc, and with significant correlations between zinc-sulfur and zinc-nickel. The Optical Particle Sizer (OPS) data, hygroscopicity and optical properties of atmospheric aerosol are consistent with the typical oil-derived gaseous emissions (e.g. sulfur dioxide and methane) that strongly influence the mixing state of particles and their size distributions. Continuous combustion processes at COVA were found to be responsible for Equivalent Black Carbon (EBC) concentrations from their relevant contribution to the total number of fine particles. The expected significant contribution of WS (water soluble) and BC (Black Carbon) components to the total Aerosol Optical Depth (AOD) are consistent with the results from the radiometric model especially for July 3 and 16.

Vegetable Oil-Loaded Nanocapsules: Innovative Alternative for Incorporating Drugs for Parenteral Administration.

PubMed

Venturinil, C G; Bruinsmann, A; Oliveira, C P; Contri, R V; Pohlmann, A R; Guterres, S S

2016-02-01

An innovative nanocapsule formulation for parenteral administration using selected vegetable oils (mango, jojoba, pequi, oat, annatto, calendula, and chamomile) was developed that has the potential to encapsulate various drugs. The vegetable oil-loaded nanocapsules were prepared by interfacial deposition and compared with capric/caprylic triglyceride-loaded lipid core nanocapsules. The major objective was to investigate the effect of vegetable oils on particle size distribution and physical stability and to determine the hemolytic potential of the nanocapsules, considering their applicability for intravenous administration. Taking into account the importance of accurately determining particle size for the selected route of administration, different size characterization techniques were employed, such as Laser Diffraction, Dynamic Light Scattering, Multiple Light Scattering, Nanoparticle Tracking Analysis, and Transmission Electronic Microscopy. Laser diffraction studies indicated that the mean particle size of all nanocapsules was below 300 nm. For smaller particles, the laser diffraction and multiple light scattering data were in agreement (D[3,2]-130 nm). Dynamic light scattering and nanoparticle tracking analysis, two powerful techniques that complement each other, exhibited size values between 180 and 259 nm for all nanoparticles. Stability studies demonstrated a tendency of particle creaming for jojoba-nanocapsules and sedimentation for the other nanoparticles; however, no size variation occurred over 30 days. The hemolysis test proved the hemocompatibility of all nanosystems, irrespective of the type of oil. Although all developed nanocapsules presented the potential for parenteral administration, jojoba oil-loaded nanocapsules were selected as the most promising nanoformulation due to their low average size and high particle size homogeneity.

Engineered particles demonstrate improved flow properties at elevated drug loadings for direct compression manufacturing.

PubMed

Trementozzi, Andrea N; Leung, Cheuk-Yui; Osei-Yeboah, Frederick; Irdam, Erwin; Lin, Yiqing; MacPhee, J Michael; Boulas, Pierre; Karki, Shyam B; Zawaneh, Peter N

2017-05-15

Optimizing powder flow and compaction properties are critical for ensuring a robust tablet manufacturing process. The impact of flow and compaction properties of the active pharmaceutical ingredient (API) becomes progressively significant for higher drug load formulations, and for scaling up manufacturing processes. This study demonstrated that flow properties of a powder blend can be improved through API particle engineering, without critically impacting blend tabletability at elevated drug loadings. In studying a jet milled API (D 50 =24μm) and particle engineered wet milled API (D 50 =70μm and 90μm), flow functions of all API lots were similarly poor despite the vast difference in average particle size (ff c <4). This finding strays from the common notion that powder flow properties are directly correlated to particle size distribution. Upon adding excipients, however, clear trends in flow functions based on API particle size were observed. Wet milled API blends had a much improved flow function (ff c >10) compared with the jet milled API blends. Investigation of the compaction properties of both wet and jet milled powder blends also revealed that both jet and wet milled material produced robust tablets at the drug loadings used. The ability to practically demonstrate this uncommon observation that similarly poor flowing APIs can lead to a marked difference upon blending is important for pharmaceutical development. It is especially important in early phase development during API selection, and is advantageous particularly when material-sparing techniques are utilized. Copyright © 2017 Elsevier B.V. All rights reserved.

Vapor-phase photo-oxidation of methanol over nanosize titanium dioxide clusters dispersed in MCM-41 host material part 1: synthesis and characterization.

PubMed

Bhattacharya, K; Tripathi, A K; Dey, G K; Gupta, N M

2005-05-01

Nanosize clusters of titania were dispersed in mesoporous MCM-41 silica matrix with the help of the incipient wet-impregnation route, using an isopropanol solution of titanium isopropoxide as precursor. The clusters thus formed were of pure anatase phase and their size depended upon the titania loading. In the case of low (< 15 wt %) loadings, the TiO2 particles were X-ray and laser-Raman amorphous, confirming very high dispersion. These particles were mostly of < or = 2 nm size. On the other hand, larger size clusters (2-15 nm) were present in a sample with a higher loading of approximately 21 wt %. These particles of titania, irrespective of their size, exhibited an absorbance behavior similar to that of bulk TiO2. Powder X-ray diffraction, N2-adsorption and transmission electron microscopy results showed that while smaller size particles were confined mostly inside the pore system, the larger size particles occupied the external surface of the host matrix. At the same time, the structural integrity of the host was maintained even though some deformation in the pore system was noticed in the case of the sample having highest loading. The core level X-ray photoelectron spectroscopy results revealed a + 4 valence state of Ti in all the samples. A positive binding energy shift and the increase of the width of Ti 2p peaks were observed, however, with the decrease in the particle size of supported titania crystallites, indicative of a microenvironment for surface sites that is different from that of the bulk.

Experimental Measurements of the Effects of Photo-chemical Oxidation on Aerosol Emissions in Aircraft Exhaust

NASA Astrophysics Data System (ADS)

Miracolo, M. A.; Presto, A. A.; Hennigan, C. J.; Nguyen, N.; Ranjan, M.; Reeder, A.; Lipsky, E.; Donahue, N. M.; Robinson, A. L.

2009-12-01

Many military and commercial airfields are located in non-attainment areas for particulate matter (PM2.5), but the contribution of emissions from in-use aircraft to local and regional PM2.5 concentrations is uncertain. In collaboration with the Pennsylvania Air National Guard 171st Air Refueling Wing, the Carnegie Mellon University (CMU) Mobile Laboratory was deployed to measure fresh and aged emissions from a CFM56-2B1 gas-turbine engine mounted on a KC-135 Stratotanker airframe. The CFM-56 family of engine powers many different types of military and civilian aircraft, including the Boeing 737 and several Airbus models. It is one of the most widely deployed models of engines in the world. The goal of this work was to measure the gas-particle partitioning of the fresh emissions at atmospherically relevant conditions and to investigate the effect of atmospheric oxidation on aerosol loadings as the emissions age. Emissions were sampled from an inlet installed one meter downstream of the engine exit plane and transferred into a portable smog chamber via a heated inlet line. Separate experiments were conducted at different engine loads ranging from ground idle to take-off rated thrust. During each experiment, some diluted exhaust was added to the chamber and the volatility of the fresh emissions was then characterized using a thermodenuder. After this characterization, the chamber was exposed to either ambient sunlight or UV lights to initiate photochemical oxidation, which produced secondary aerosol and ozone. A suite of gas and particle-phase instrumentation was used to characterize the evolution of the gas and particle-phase emissions, including an aerosol mass spectrometer (AMS) to measure particle size and composition distributions. Fresh emissions of fine particles varied with engine load with peak emission factors at low and high loads. At high engine loads, the fresh emissions were dominated by black carbon; at low loads volatile organic carbon emissions were dominant. At low loads, photo-oxidation increased aerosol loadings in the chamber by a factor of fifty. We attribute this substantial secondary organic aerosol (SOA) production to oxidation of low-volatility organic vapors emitted under low loads. At higher loads, we see more modest secondary aerosol production from both organics and inorganics. Therefore secondary aerosol production can substantially exceed the direct aerosol emissions from aircraft. The results underscore the dramatic effects that photo-oxidation has on aerosol emissions from aircraft.

Annual trace-metal load estimates and flow-weighted concentrations of cadmium, lead, and zinc in the Spokane River basin, Idaho and Washington, 1999-2004

USGS Publications Warehouse

Donato, Mary M.

2006-01-01

Streamflow and trace-metal concentration data collected at 10 locations in the Spokane River basin of northern Idaho and eastern Washington during 1999-2004 were used as input for the U.S. Geological Survey software, LOADEST, to estimate annual loads and mean flow-weighted concentrations of total and dissolved cadmium, lead, and zinc. Cadmium composed less than 1 percent of the total metal load at all stations; lead constituted from 6 to 42 percent of the total load at stations upstream from Coeur d'Alene Lake and from 2 to 4 percent at stations downstream of the lake. Zinc composed more than 90 percent of the total metal load at 6 of the 10 stations examined in this study. Trace-metal loads were lowest at the station on Pine Creek below Amy Gulch, where the mean annual total cadmium load for 1999-2004 was 39 kilograms per year (kg/yr), the mean estimated total lead load was about 1,700 kg/yr, and the mean annual total zinc load was 14,000 kg/yr. The trace-metal loads at stations on North Fork Coeur d'Alene River at Enaville, Ninemile Creek, and Canyon Creek also were relatively low. Trace-metal loads were highest at the station at Coeur d'Alene River near Harrison. The mean annual total cadmium load was 3,400 kg/yr, the mean total lead load was 240,000 kg/yr, and the mean total zinc load was 510,000 kg/yr for 1999-2004. Trace-metal loads at the station at South Fork Coeur d'Alene River near Pinehurst and the three stations on the Spokane River downstream of Coeur d'Alene Lake also were relatively high. Differences in metal loads, particularly lead, between stations upstream and downstream of Coeur d'Alene Lake likely are due to trapping and retention of metals in lakebed sediments. LOADEST software was used to estimate loads for water years 1999-2001 for many of the same sites discussed in this report. Overall, results from this study and those from a previous study are in good agreement. Observed differences between the two studies are attributable to streamflow differences in the two regression models, 1999-2001 and 1999-2004. Flow-weighted concentrations (FWCs) calculated from the estimated loads for 1999-2004 were examined to aid interpretation of metal load estimates, which were influenced by large spatial and temporal variations in streamflow. FWCs of total cadmium ranged from 0.04 micrograms per liter (?g/L) at Enaville to 14 ?g/L at Ninemile Creek. Total lead FWCs were lowest at Long Lake (1.3 ?g/L) and highest at Ninemile Creek (120 ?g/L). Elevated total lead FWCs at Harrison confirmed that the high total lead loads at this station were not simply due to higher streamflow. Conversely, relatively low total lead loads combined with high total lead FWCs at Ninemile and Canyon Creeks reflected low streamflow but high concentrations of total lead. Very low total lead FWCs (1.3 to 2.7 ?g/L) at the stations downstream of Coeur d'Alene Lake are a result both of deposition of lead-laden sediments in the lake and dilution by additional streamflow. Total zinc FWCs also demonstrated the effect of streamflow on load calculations, and highlighted source areas for zinc in the basin. Total zinc FWCs at Canyon and Ninemile Creeks, 1,600 ?g/L and 2,200 ?g/L, respectively, were by far the highest in the basin but contributed among the lowest total zinc loads due to their relatively low streamflow. Total zinc FWCs ranged from 38 to 67 ?g/L at stations downstream of Coeur d'Alene Lake, but total zinc load estimates at these stations were relatively high because of high mean streamflow compared to other stations in the basin. Long-term regression models for 1991 to 2003 or 2004 were developed and annual trace-metal loads and FWCs were estimated for Pinehurst, Enaville, Harrison, and Post Falls to better understand the variability of metal loading with time. Long-term load estimates are similar to the results for 1999-2004 in terms of spatial distribution of metal loads throughout the basin. LOADEST results for 1991-2004 indicated that statistically significant downward temporal trends for dissolved and total cadmium, dissolved zinc, and total lead were occurring at Pinehurst, Enaville, Harrison, and Post Falls. Additionally, data for Enaville and Post Falls showed significant downward trends for dissolved lead and total zinc loads; Harrison total zinc loads also decreased with time. The Mann-Kendall trend test results agreed with the LOADEST trend results in most cases, but gave contradictory results for total zinc at Pinehurst and at Post Falls. Long- and short-term load and flow-weighted concentration estimates yielded valuable information about metal storage and transport processes, and demonstrated that water quality data are a great aid in understanding these processes.

Computing fluid-particle interaction forces for nano-suspension droplet spreading: molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Zhou, Weizhou; Shi, Baiou; Webb, Edmund

2017-11-01

Recently, there are many experimental and theoretical studies to understand and control the dynamic spreading of nano-suspension droplets on solid surfaces. However, fundamental understanding of driving forces dictating the kinetics of nano-suspension wetting and spreading, especially capillary forces that manifest during the process, is lacking. Here, we present results from atomic scale simulations that were used to compute forces between suspended particles and advancing liquid fronts. The role of nano-particle size, particle loading, and interaction strength on forces computed from simulations will be discussed. Results demonstrate that increasing the particle size dramatically changes observed wetting behavior from depinning to pinning. From simulations on varying particle size, a relationship between computed forces and particle size is advanced and compared to existing expressions in the literature. High particle loading significantly slowed spreading kinetics, by introducing tortuous transport paths for liquid delivery to the advancing contact line. Lastly, we show how weakening the interaction between the particle and the underlying substrate can change a system from exhibiting pinning behavior to de-pinning.

Manufacturing of a Secretoneurin Drug Delivery System with Self-Assembled Protamine Nanoparticles by Titration

PubMed Central

Scheicher, Bernhard; Lorenzer, Cornelia; Gegenbauer, Katrin; Partlic, Julia; Andreae, Fritz; Kirsch, Alexander H.; Rosenkranz, Alexander R.; Werzer, Oliver

2016-01-01

Since therapeutic peptides and oligonucleotides are gathering interests as active pharmaceutical ingredients (APIs), nanoparticulate drug delivery systems are becoming of great importance. Thereby, the possibility to design drug delivery systems according to the therapeutic needs of APIs enhances clinical implementation. Over the last years, the focus of our group was laid on protamine-oligonucleotide-nanoparticles (so called proticles), however, the possibility to modify the size, zeta potential or loading efficiencies was limited. Therefore, at the present study we integrated a stepwise addition of protamine (titration) into the formation process of proticles loaded with the angiogenic neuropeptide secretoneurin (SN). A particle size around 130 nm was determined when proticles were assembled by the commonly used protamine addition at once. Through application of the protamine titration process it was possible to modify and adjust the particle size between approx. 120 and 1200 nm (dependent on mass ratio) without influencing the SN loading capacity. Dynamic light scattering pointed out that the difference in particle size was most probably the result of a secondary aggregation. Initially-formed particles of early stages in the titration process aggregated towards bigger assemblies. Atomic-force-microscopy images also revealed differences in morphology along with different particle size. In contrast, the SN loading was only influenced by the applied mass ratio, where a slight saturation effect was observable. Up to 65% of deployed SN could be imbedded into the proticle matrix. An in-vivo biodistribution study (i.m.) showed a retarded distribution of SN from the site of injection after the application of a SN-proticle formulation. Further, it was demonstrated that SN loaded proticles can be successfully freeze-dried and resuspended afterwards. To conclude, the integration of the protamine titration process offers new possibilities for the formulation of proticles in order to address key parameters of drug delivery systems as size, API loading or modified drug release. PMID:27828968

Anomalous diffusion for bed load transport with a physically-based model

NASA Astrophysics Data System (ADS)

Fan, N.; Singh, A.; Foufoula-Georgiou, E.; Wu, B.

2013-12-01

Diffusion of bed load particles shows both normal and anomalous behavior for different spatial-temporal scales. Understanding and quantifying these different types of diffusion is important not only for the development of theoretical models of particle transport but also for practical purposes, e.g., river management. Here we extend a recently proposed physically-based model of particle transport by Fan et al. [2013] to further develop an Episodic Langevin equation (ELE) for individual particle motion which reproduces the episodic movement (start and stop) of sediment particles. Using the proposed ELE we simulate particle movements for a large number of uniform size particles, incorporating different probability distribution functions (PDFs) of particle waiting time. For exponential PDFs of waiting times, particles reveal ballistic motion in short time scales and turn to normal diffusion at long time scales. The PDF of simulated particle travel distances also shows a change in its shape from exponential to Gamma to Gaussian with a change in timescale implying different diffusion scaling regimes. For power-law PDF (with power - μ) of waiting times, the asymptotic behavior of particles at long time scales reveals both super-diffusion and sub-diffusion, however, only very heavy tailed waiting times (i.e. 1.0 < μ < 1.5) could result in sub-diffusion. We suggest that the contrast between our results and previous studies (for e.g., studies based on fractional advection-diffusion models of thin/heavy tailed particle hops and waiting times) results could be due the assumption in those studies that the hops are achieved instantaneously, but in reality, particles achieve their hops within finite times (as we simulate here) instead of instantaneously, even if the hop times are much shorter than waiting times. In summary, this study stresses on the need to rethink the alternative models to the previous models, such as, fractional advection-diffusion equations, for studying the anomalous diffusion of bed load particles. The implications of these results for modeling sediment transport are discussed.

Effects of damage and thermal residual stresses on the overall elastoplastic behavior of particle-reinforced metal matrix composites

NASA Astrophysics Data System (ADS)

Liu, Haitao

The objective of the present study is to investigate damage mechanisms and thermal residual stresses of composites, and to establish the frameworks to model the particle-reinforced metal matrix composites with particle-matrix interfacial debonding, particle cracking or thermal residual stresses. An evolutionary interfacial debonding model is proposed for the composites with spheroidal particles. The construction of the equivalent stiffness is based on the fact that when debonding occurs in a certain direction, the load-transfer ability will lose in that direction. By using this equivalent method, the interfacial debonding problem can be converted into a composite problem with perfectly bonded inclusions. Considering the interfacial debonding is a progressive process in which the debonding area increases in proportion to external loading, a progressive interfacial debonding model is proposed. In this model, the relation between external loading and the debonding area is established using a normal stress controlled debonding criterion. Furthermore, an equivalent orthotropic stiffness tensor is constructed based on the debonding areas. This model is able to study the composites with randomly distributed spherical particles. The double-inclusion theory is recalled to model the particle cracking problems. Cracks inside particles are treated as penny-shape particles with zero stiffness. The disturbed stress field due to the existence of a double-inclusion is expressed explicitly. Finally, a thermal mismatch eigenstrain is introduced to simulate the inconsistent expansions of the matrix and the particles due to the difference of the coefficients of thermal expansion. Micromechanical stress and strain fields are calculated due to the combination of applied external loads and the prescribed thermal mismatch eigenstrains. For all of the above models, ensemble-volume averaging procedures are employed to derive the effective yield function of the composites. Numerical simulations are performed to analyze the effects of various parameters and several good agreements between our model's predictions and experimental results are obtained. It should be mentioned that all of expressions in the frameworks are explicitly derived and these analytical results are easy to be adopted in other related investigations.

Protein-Containing Multilayer Capsules by Templating on Mesoporous CaCO3 Particles: POST- and PRE-Loading Approaches.

PubMed

Balabushevich, Nadezhda G; Lopez de Guerenu, Anna V; Feoktistova, Natalia A; Skirtach, Andre G; Volodkin, Dmitry

2016-01-01

Encapsulation of model proteins (catalase, insulin, aprotinin) into multilayer dextran sulphate/protamin capsules by templating on CaCO3 microparticles is investigated employing: (i) PRE-loading into CaCO3 particles by adsorption or co-synthesis and (ii) POST-loading into performed capsules. Protein encapsulation is governed by both its size and electrostatic interactions with the carbonate microparticles and multilayer shell. PRE-loading enables improved encapsulation compared to POST-loading (catalase content in capsules 630 and 70 mg · g(-1)). Bioactivity of encapsulated protein is not affected by interaction with multilayers but may be reduced at slightly alkaline pH due to CaCO3 hydrolysis. This study might help to successfully encapsulate fragile bio-macromolecules into multilayer capsules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospun cellulose acetate composites containing supported metal nanoparticles for antifungal membranes.

PubMed

Quirós, Jennifer; Gonzalo, Soledad; Jalvo, Blanca; Boltes, Karina; Perdigón-Melón, José Antonio; Rosal, Roberto

2016-09-01

Electrospun cellulose acetate composites containing silver and copper nanoparticles supported in sepiolite and mesoporous silica were prepared and tested as fungistatic membranes against the fungus Aspergillus niger. The nanoparticles were in the 3-50nm range for sepiolite supported materials and limited by the size of mesopores (5-8nm) in the case of mesoporous silica. Sepiolite and silica were well dispersed within the fibers, with larger aggregates in the micrometer range, and allowed a controlled release of metals to create a fungistatic environment. The effect was assessed using digital image analysis to evaluate fungal growth rate and fluorescence readings using a viability stain. The results showed that silver and copper nanomaterials significantly impaired the growth of fungi when the spores were incubated either in direct contact with particles or included in cellulose acetate composite membranes. The fungistatic effect took place on germinating spores before hyphae growth conidiophore formation. After 24h the cultures were separated from fungistatic materials and showed growth impairment only due to the prior exposure. Growth reduction was important for all the particles and membranes with respect to non-exposed controls. The effect of copper and silver loaded materials was not significantly different from each other with average reductions around 70% for bare particles and 50% for membranes. Copper on sepiolite was particularly efficient with a decrease of metabolic activity of up to 80% with respect to controls. Copper materials induced rapid maturation and conidiation with fungi splitting in sets of subcolonies. Metal-loaded nanomaterials acted as reservoirs for the controlled release of metals. The amount of silver or copper released daily by composite membranes represented roughly 1% of their total load of metals. Supported nanomaterials encapsulated in nanofibers allow formulating active membranes with high antifungal performance at the same time minimizing the risk of nanoparticle release into the environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Parameters influencing the course of passive drug loading into lipid nanoemulsions.

PubMed

Göke, Katrin; Bunjes, Heike

2018-05-01

Passive drug loading can be used to effectively identify suitable colloidal lipid carrier systems for poorly water-soluble drugs. This method comprises incubation of preformed carrier systems with drug powder and subsequent determination of the resulting drug load of the carrier particles. Until now, the passive loading mechanism is unknown, which complicates reliable routine use. In this work, the influence of drug characteristics on the course of passive loading was investigated systematically varying drug surface area and drug solubility. Fenofibrate and flufenamic acid were used as model drugs; the carrier system was a trimyristin nanodispersion. Loading progress was analyzed by UV spectroscopy or by a novel method based on differential scanning calorimetry. While increasing drug solubility by micelle incorporation did not speed up passive loading, a large drug surface area and high water solubility were key parameters for fast loading. Since both factors are crucial in drug dissolution as described by the Noyes-Whitney equation, these findings point to a dissolution-diffusion-based passive loading mechanism. Accordingly, passive loading also occurred when drug and carrier particles were separated by a dialysis membrane. Knowledge of the loading mechanism allows optimizing the conditions for future passive loading studies and assessing the limitations of the method. Copyright © 2017 Elsevier B.V. All rights reserved.

Polycyclic aromatic hydrocarbons (PAHs) and their derivatives (oxygenated-PAHs, nitrated-PAHs and azaarenes) in size-fractionated particles emitted in an urban road tunnel

NASA Astrophysics Data System (ADS)

Alves, C. A.; Vicente, A. M. P.; Gomes, J.; Nunes, T.; Duarte, M.; Bandowe, B. A. M.

2016-11-01

A sampling campaign of size segregated particulate matter (PM0.5, PM0.5-1, PM1-2.5 and PM2.5-10) was carried out at two sites, one in a road tunnel (Braga, Portugal) and another at an urban background location in the neighbourhood. Particle-bound polycyclic aromatic compounds were extracted with organic solvents and analysed by gas chromatography-mass spectrometry. Twenty six parent and alkyl-polycyclic aromatic hydrocarbons (PAHs), 4 azaarenes (AZAs), 15 nitrated and 15 oxygenated derivatives (NPAHs and OPAHs) were analysed. On average, submicron particles (PM1) in the tunnel comprised 93, 91, 96 and 71% of the total PAHs, OPAHs, NPAHs and AZAs mass in PM10, respectively. Tunnel to outdoor PAH concentration ratios between 10 and 14 reveal the strong contribution of fresh exhaust emissions to the PM loads. The dominant PAHs in the tunnel were pyrene, retene and benzo[ghi]perylene, accounting for 20, 17 and 8% of the total PAH levels in PM10, respectively. Isomer ratios indicated the importance of unburnt fuel as a significant PAH source. The only NPAH consistently present in all samples was 5-nitroacenaphthene. Indanone and 1,8-naphthalic anhydride were the most abundant OPAHs, accounting for 25 and 17% of the total concentrations of this organic class, respectively. Other abundant OPAHs were 1,4-naphthoquinone, 9-fluorenone, 1,2-acenaphthylenequinone and 7H-benz[de]anthracene-7-one. Individual emission factors (μg veh- 1 km- 1) were estimated and compared with those obtained in other tunnel studies.

Fracto-emission from single fibres of Kevlar

NASA Technical Reports Server (NTRS)

Dickinson, J. T.; Jahan-Latibari, A.; Jensen, L. C.

1985-01-01

Fracto-emission (FE) is the emission of particles (e.g. electrons, ions and photons) during and following fracture. In this paper, we present data on electron emission (EE) and positive ion emission (PIE) from the tensile fracture of Kevlar single fibers. The fibers were initially fractured in pure tension, where a stranded form of fracture was observed, often with multiple peaks spread over several hundred microseconds. The loading condition was then changed by stretching and breaking the fibers over a dull metal edge. With this change in the loading, different forms of fracture were observed, each with distinctive forms of emission curves. When fracture was accompanied by extensive fibril formation, total emission was high and both EE and PIE decay times were long relative to fractures in which little fibril formation occurred. The results of this study suggest that FE has some applicability as a tool for the detection of fracture mechanisms of single fibers.

Preparation and characterization of temperature-responsive magnetic composite particles for multi-modal cancer therapy.

PubMed

Yao, Aihua; Chen, Qi; Ai, Fanrong; Wang, Deping; Huang, Wenhai

2011-10-01

The temperature-responsive magnetic composite particles were synthesized by emulsion-free polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (Am) in the presence of oleic acid-modified Fe(3)O(4) nanoparticles. The magnetic properties and heat generation ability of the composite particles were characterized. Furthermore, temperature and alternating magnetic field (AMF) triggered drug release behaviors of vitamin B(12)-loaded composite particles were also examined. It was found that composite particles enabled drug release to be controlled through temperature changes in the neighborhood of lower critical solution temperature. Continuous application of AMF resulted in an accelerated release of the loaded drug. On the other hand, intermittent AMF application to the composite particles resulted in an "on-off", stepwise release pattern. Longer release duration and larger overall release could be achieved by intermittent application of AMF as compared to continuous magnetic field. Such composite particles may be used for magnetic drug targeting followed by simultaneous hyperthermia and drug release.

Influence of diesel fuel sulfur on nanoparticle emissions from city buses.

PubMed

Ristovski, Z D; Jayaratne, E R; Lim, M; Ayoko, G A; Morawska, L

2006-02-15

Particle emissions from twelve buses, operating alternately on low sulfur (LS; 500 ppm) and ultralow sulfur (ULS; 50 ppm) diesel fuel, were monitored. The buses were 1-19 years old and had no after-treatment devices fitted. Measurements were carried out at four steady-state operational modes on a chassis dynamometer using a mini dilution tunnel (PM mass measurement) and a Dekati ejector diluter as a secondary diluter (SMPS particle number). The mean particle number emission rate (s(-1)) of the buses, in the size range 8-400 nm, using ULS diesel was 31% to 59% lower than the rate using LS diesel in all four modes. The fractional reduction was highest in the newest buses and decreased with mileage upto about 500,000 km, after which no further decrease was apparent. However, the mean total suspended particle (TSP) mass emission rate did not show a systematic difference between the two fuel types. When the fuel was changed from LS to ULS diesel, the reduction in particle number was mainly in the nanoparticle size range. Over all operational modes, 58% of the particles were smaller than 50 nm with LS fuel as opposed to just 45% with ULS fuel, suggesting that sulfur in diesel fuel was playing a major role in the formation of nanoparticles. The greatest influence of the fuel sulfur content was observed at the highest engine load, where 74% of the particles were smaller than 50 nm with LS diesel compared to 43% with ULS diesel.

A study on the preparation of floating photocatalyst supported by hollow TiO2 and its performance

NASA Astrophysics Data System (ADS)

Wang, Jingang; He, Bin; Kong, Xiang Z.

2015-02-01

This research used hollow glass microspheres (HGMS) as carrier and polystyrene (PSt) as template. PSt was loaded on HGMS surface through the modification by silane coupler. Next, amorphous titanium dioxide (TiO2) produced through tetrabutyl titanate (TBT) hydrolysis precipitated on PSt surface, forming HGMS/PSt/TiO2 particles. Lastly, using the calcinations method, this research obtained anatase TiO2, eliminated PSt, and ultimately acquired composite particles with hollow TiO2 loaded on HGMS surface (HGMSHT). SEM results presented that hollow TiO2 was compact on HGMS surface and a multilayer network structure was formed. The specific surface area of HGMSHT particles was 26 m2/g, which was much larger than that of HGMS/TiO2 (HGMST) composite particles (5.6 m2/g) through direct TBT hydrolysis. Results of catalytic degradation experiment with Rhodamine B and phenol under UV light and sunlight demonstrated that due to larger TiO2 load capacity and specific surface area, the catalytic activity of HGMSHT composite particles was significantly more desirable than that of HGMST, and the catalyst presented satisfactory stability.

Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

PubMed

Manga, Mohamed S; York, David W

2017-09-12

Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

The effect of detonation wave incidence angle on the acceleration of flyers by explosives heavily laden with inert additives

NASA Astrophysics Data System (ADS)

Loiseau, Jason; Georges, William; Frost, David L.; Higgins, Andrew J.

2017-01-01

The incidence angle of a detonation wave in a conventional high explosive influences the acceleration and terminal velocity of a metal flyer by increasing the magnitude of the material velocity imparted by the transmitted shock wave as the detonation is tilted towards normal loading. For non-ideal explosives heavily loaded with inert additives, the detonation velocity is typically subsonic relative to the flyer sound speed, leading to shockless accelerations when the detonation is grazing. Further, in a grazing detonation the particles are initially accelerated in the direction of the detonation and only gain velocity normal to the initial orientation of the flyer at later times due to aerodynamic drag as the detonation products expand. If the detonation wave in a non-ideal explosive instead strikes the flyer at normal incidence, a shock is transmitted into the flyer and the first interaction between the particle additives and the flyer occurs due to the imparted material velocity from the passage of the detonation wave. Consequently, the effect of incidence angle and additive properties may play a more prominent role in the flyer acceleration. In the present study we experimentally compared normal detonation loadings to grazing loadings using a 3-mm-thick aluminum slapper to impact-initiate a planar detonation wave in non-ideal explosive-particle admixtures, which subsequently accelerated a second 6.4-mm-thick flyer. Flyer acceleration was measured with heterodyne laser velocimetry (PDV). The explosive mixtures considered were packed beds of glass or steel particles of varying sizes saturated with sensitized nitromethane, and gelled nitromethane mixed with glass microballoons. Results showed that the primary parameter controlling changes in flyer velocity was the presence of a transmitted shock, with additive density and particle size playing only secondary roles. These results are similar to the grazing detonation experiments, however under normal loading the largest, higher density particles yielded the highest terminal flyer velocity, whereas in the grazing experiments the larger, low density particles yielded the highest terminal velocity.

The impact of particle size and initial solid loading on thermochemical pretreatment of wheat straw for improving sugar recovery.

PubMed

Rojas-Rejón, Oscar A; Sánchez, Arturo

2014-07-01

This work studies the effect of initial solid load (4-32 %; w/v, DS) and particle size (0.41-50 mm) on monosaccharide yield of wheat straw subjected to dilute H(2)SO(4) (0.75 %, v/v) pretreatment and enzymatic saccharification. Response surface methodology (RSM) based on a full factorial design (FFD) was used for the statistical analysis of pretreatment and enzymatic hydrolysis. The highest xylose yield obtained during pretreatment (ca. 86 %; of theoretical) was achieved at 4 % (w/v, DS) and 25 mm. The solid fraction obtained from the first set of experiments was subjected to enzymatic hydrolysis at constant enzyme dosage (17 FPU/g); statistical analysis revealed that glucose yield was favored with solids pretreated at low initial solid loads and small particle sizes. Dynamic experiments showed that glucose yield did not increase after 48 h of enzymatic hydrolysis. Once established pretreatment conditions, experiments were carried out with several initial solid loading (4-24 %; w/v, DS) and enzyme dosages (5-50 FPU/g). Two straw sizes (0.41 and 50 mm) were used for verification purposes. The highest glucose yield (ca. 55 %; of theoretical) was achieved at 4 % (w/v, DS), 0.41 mm and 50 FPU/g. Statistical analysis of experiments showed that at low enzyme dosage, particle size had a remarkable effect over glucose yield and initial solid load was the main factor for glucose yield.

The effects of particle properties on nanoparticle drug retention and release in dynamic minoxidil foams.

PubMed

Zhao, Yanjun; Brown, Marc B; Jones, Stuart A

2010-01-04

Nanocarriers may act as useful tools to deliver therapeutic agents to the skin. However, balancing the drug-particle interactions; to ensure adequate drug loading, with the drug-vehicle interactions; to allow efficient drug release, presents a significant challenge using traditional semi-solid vehicles. The aim of this study was to determine how the physicochemical properties of nanoparticles influenced minoxidil release pre and post dose application when formulated as a simple aqueous suspension compared to dynamic hydrofluoroalkane (HFA) foams. Minoxidil loaded lipid nanoparticles (LN, 1.4 mg/ml, 50 nm) and polymeric nanoparticles with a lipid core (PN, 0.6 mg/ml, 260 nm) were produced and suspended in water to produce the aqueous suspensions. These aqueous suspensions were emulsified with HFA using pluronic surfactant to generate the foams. Approximately 60% of the minoxidil loaded into the PN and 80% of the minoxidil loaded into the LN was released into the external aqueous phase 24h after production. Drug permeation was superior from the PN, i.e. it was the particle that retained the most drugs, irrespective of the formulation method. Premature drug release, i.e. during storage, resulted in the performance of the topical formulation being dictated by the thermodynamic activity of the solubilised drug not the particle properties.

Quantifying Grain-Size Variability of Metal Pollutants in Road-Deposited Sediments Using the Coefficient of Variation

PubMed Central

Wang, Xiaoxue; Li, Xuyong

2017-01-01

Particle grain size is an important indicator for the variability in physical characteristics and pollutants composition of road-deposited sediments (RDS). Quantitative assessment of the grain-size variability in RDS amount, metal concentration, metal load and GSFLoad is essential to elimination of the uncertainty it causes in estimation of RDS emission load and formulation of control strategies. In this study, grain-size variability was explored and quantified using the coefficient of variation (Cv) of the particle size compositions, metal concentrations, metal loads, and GSFLoad values in RDS. Several trends in grain-size variability of RDS were identified: (i) the medium class (105–450 µm) variability in terms of particle size composition, metal loads, and GSFLoad values in RDS was smaller than the fine (<105 µm) and coarse (450–2000 µm) class; (ii) The grain-size variability in terms of metal concentrations increased as the particle size increased, while the metal concentrations decreased; (iii) When compared to the Lorenz coefficient (Lc), the Cv was similarly effective at describing the grain-size variability, whereas it is simpler to calculate because it did not require the data to be pre-processed. The results of this study will facilitate identification of the uncertainty in modelling RDS caused by grain-size class variability. PMID:28788078

Antibacterial and anti-inflammatory drug delivery properties on cotton fabric using betamethasone-loaded mesoporous silica particles stabilized with chitosan and silicone softener.

PubMed

Hashemikia, Samaneh; Hemmatinejad, Nahid; Ahmadi, Ebrahim; Montazer, Majid

2016-10-01

In this study, mesoporous silica particles with a hexagonal structure (SBA-15) were synthesized and modified with (3-aminopropyl) triethoxysilane, and used as a carrier for anti-inflammatory drug, betamethasone sodium phosphate. Drug-loaded silica particles were grafted on the cotton fabric surface using chitosan and polysiloxane reactive softener as a soft and safe fixing agent to develop an antibacterial cotton fabric with drug delivery properties. Cytometry assays revealed that synthesized silica have no cytotoxicity against human peripheral blood mononuclear cells. Accordingly, the produced drug-loaded nanostructures can be applied via different routes, such as wound dressing. Drug delivery profile of the treated fabrics were investigated and compared. The drug release rate followed the conventional Higuchi model. The treated cotton fabrics were tested and evaluated using scanning electron microscope images, bending length, air permeability, washing durability and anti-bacterial properties. It was found that the chitosan-/softener-treated fabrics compounded with drug-loaded silica particles have a good drug delivery performance and exhibited a powerful antibacterial activity against both Escherichia coli and Staphylococcus aureus even after five washing cycles. The produced antibacterial cotton fabric with drug delivery properties could be proposed as a suitable material for many medical and hygienic applications.

Confocal Raman characterization of different protein desorption behaviors from chromatographic particles.

PubMed

Xiao, Yuewu; Stone, Thomas; Moya, Wilson; Killian, Paul; Herget, Thomas

2014-01-21

Confocal Raman spectroscopy is a nondestructive analytical technique that combines the chemical information from vibrational spectroscopy with the spatial resolution of confocal microscopy. It was applied, for the first time, to measure protein desorption from chromatographic particles. Monoclonal antibody was loaded onto the Fractogel EMD SO3 (M) cation exchanger at either pH 5 or pH 4. Confocal Raman measurement suggests that only the protein loaded at pH 5 is able to release from chromatographic particles in the elution buffer. Detailed comparison of high-quality spectra indicates that, while proteins loaded at both pH values showed a predominant β-sheet conformation, protein loaded at pH 4 has a broader amide I band with more intensity in the >1680 cm(-1) region. This small but clear and reproducible amide I bandwidth increase is not observed for protein in the solution state at pH 4. No definitive assignment of the increased Raman intensity in the >1680 cm(-1) region could be made, but it might be related to structural changes involved in the association of protein molecules in the adsorbed state, which helps to explain the nearly 100% retention under elution conditions of the monoclonal antibody adsorbed at pH 4 in chromatographic particles.

Simulation of Helical Flow Hydrodynamics in Meanders and Advection-Turbulent Diffusion Using Smoothed Particle Hydrodynamics

NASA Astrophysics Data System (ADS)

Gusti, T. P.; Hertanti, D. R.; Bahsan, E.; Soeryantono, H.

2013-12-01

Particle-based numerical methods, such as Smoothed Particle Hydrodynamics (SPH), may be able to simulate some hydrodynamic and morphodynamic behaviors better than grid-based numerical methods. This study simulates hydrodynamics in meanders and advection and turbulent diffusion in straight river channels using Microsoft Excel and Visual Basic. The simulators generate three-dimensional data for hydrodynamics and one-dimensional data for advection-turbulent diffusion. Fluid at rest, sloshing, and helical flow are simulated in the river meanders. Spill loading and step loading are done to simulate concentration patterns associated with advection-turbulent diffusion. Results indicate that helical flow is formed due to disturbance in morphology and particle velocity in the stream and the number of particles does not have a significant effect on the pattern of advection-turbulent diffusion concentration.

Sediment transport and capacity change in three reservoirs, Lower Susquehanna River Basin, Pennsylvania and Maryland, 1900-2012

USGS Publications Warehouse

Langland, Michael J.

2015-01-01

The U.S. Geological Survey (USGS) has conducted numerous sediment transport studies in the Susquehanna River and in particular in three reservoirs in the Lower Susquehanna River Basin to determine sediment transport rates over the past century and to document changes in storage capacity. The Susquehanna River is the largest tributary to Chesapeake Bay and transports about one-half of the total freshwater input and substantial amounts of sediment and nutrients to the bay. The transported loads are affected by deposition in reservoirs (Lake Clarke, Lake Aldred, and Conowingo Reservoir) behind three hydropower dams. The geometry and texture of the deposited sediments in each reservoir upstream from the three dams has been a subject of research in recent decades. Particle size deposition and sediment scouring processes are part of the reservoir dynamics. A Total Maximum Daily Load (TMDL) for nitrogen, phosphorus, and sediment was established for Chesapeake Bay to attain water-quality standards. Six states and the District of Columbia agreed to reduce loads to the bay and to meet load allocation goals for the TMDL. The USGS has been estimating annual sediment loads at the Susquehanna River at Marietta, Pennsylvania (above Lake Clarke), and Susquehanna River at Conowingo, Maryland (below Conowingo Reservoir), since the mid-1980s to predict the mass balance of sediment transport through the reservoir system. Using streamflow and sediment data from the Susquehanna River at Harrisburg, Pennsylvania (upstream from the reservoirs), from 1900 to 1981, sediment loads were greatest in the early to mid-1900s when land disturbance activities from coal production and agriculture were at their peak. Sediment loads declined in the 1950s with the introduction of agricultural soil conservation practices. Loads were dominated by climatic factors in the 1960s (drought) and 1970s (very wet) and have been declining since the 1980s through 2012. The USGS developed a regression equation to predict the sediment scour load for daily mean streamflows greater than 300,000 cubic feet per second for the Lower Susquehanna River reservoirs. A compilation of data from various sources produced a range in total sediment transported through the reservoir system and allowed for apportioning to source (watershed or scour) for various streamflows. In 2011, Conowingo Reservoir was estimated to be about 92 percent of sediment storage capacity. Since construction of Conowingo Dam in 1929 through 2012, approximately 470 million tons of sediment was transported down the Susquehanna River into the reservoir system, approximately 290 million tons were trapped, and approximately 180 million tons were transported to Chesapeake Bay. Spatial and estimated total sand deposition in Conowingo Reservoir based on historical sediment cores indicated continued migration of sand downgradient toward the dam and the winnowing of silts and clays near the dam due to scour.

Characteristics of inhalable particulate matter concentration and size distribution from power plants in China.

PubMed

Yi, Honghong; Hao, Jiming; Duan, Lei; Li, Xinghua; Guo, Xingming

2006-09-01

In this investigation, the collection efficiency of particulate emission control devices (PECDs), particulate matter (PM) emissions, and PM size distribution were determined experimentally at the inlet and outlet of PECDs at five coal-fired power plants. Different boilers, coals, and PECDs are used in these power plants. Measurement in situ was performed by an electrical low-pressure impactor with a sampling system, which consisted of an isokinetic sampler probe, precut cyclone, and two-stage dilution system with a sample line to the instruments. The size distribution was measured over a range from 0.03 to 10 microm. Before and after all of the PECDs, the particle number size distributions display a bimodal distribution. The PM2.5 fraction emitted to atmosphere includes a significant amount of the mass from the coarse particle mode. The controlled and uncontrolled emission factors of total PM, inhalable PM (PM10), and fine PM P(M2.5) were obtained. Electrostatic precipitator (ESP) and baghouse total collection efficiencies are 96.38-99.89% and 99.94%, respectively. The minimum collection efficiency of the ESP and the baghouse both appear in the particle size range of 0.1-1 microm. In this size range, ESP and baghouse collection efficiencies are 85.79-98.6% and 99.54%. Real-time measurement shows that the mass and number concentration of PM10 will be greatly affected by the operating conditions of the PECDs. The number of emitted particles increases with increasing boiler load level because of higher combustion temperature. During test run periods, the data reproducibility is satisfactory.

Temporal variability of particulate organic carbon in the lower Changjiang (Yangtze River) in the post-Three Gorges Dam period: Links to anthropogenic and climate impacts

NASA Astrophysics Data System (ADS)

Wu, Ying; Bao, Hongyan; Yu, Hao; Zhang, Jing; Kattner, Gerhard

2015-11-01

Suspended particles from the lower Changjiang were collected monthly from 2003 to 2011, which corresponds to the three construction periods of the Three Gorges Dam. Organic carbon (%OC), organic carbon to total nitrogen molar ratio, stable carbon isotope, and terrestrial biomarkers were examined. Rating curve studies were applied for the temporal trend analysis. The composition of particulate lignin phenols exhibited clear annual and periodic variations but only minor seasonal changes. Lignin phenol ratios (vanillyl/syringyl and cinnamyl/vanillyl) indicated that the terrigenous organic matter (OM) was primarily composed of woody and nonwoody tissue derived from angiosperm plants. The low-lignin phenol yields (Λ8) in combination with higher acid to aldehyde ratios reflected a substantial contribution from soil OM to the particle samples or modifications during river transport. The temporal shift of the lignin phenol vegetation index with the sediment load during the flood seasons revealed particulate organic matter (POM) erosion from soils and the impact of hydrodynamic processes. The dam operations affected the seasonal variability of terrigenous OM fluxes, although the covariation of lignin and sediment loads with discharged water implies that unseasonal extreme conditions and climate change most likely had larger influences, because decreases in the sediment load and lignin flux alter the structure and composition of particulate OM (POM) on interannual time scales, indicating that they may be driven by climate variability. The modification of the composition and structure of POM will have significant impacts on regional carbon cycles and marine ecosystems.

Loteprednol Etabonate Nanoparticles: Optimization via Box-Behnken Design Response Surface Methodology and Physicochemical Characterization.

PubMed

Sah, Abhishek K; Suresh, Preeti K

2017-01-01

Abstract: The objective of the present work was to prepare and optimize the loteprednoletabonate (LE) loaded poly (D,L-lactide co-glycolide) (PLGA) polymer based nanoparticle carrier. The review on recent patents (US9006241, US20130224302A1, US2012/0028947A1) assisted in the selection of drug and polymer for designing nanoparticles for ocular delivery applications. The nanoparticles were prepared by solvent evaporation followed by high speed homogenization. Biodegradable polymer PLGA (50:50) grade was utilized to develop various formulations with different drug:polymer ratio. A Box-Behnken design with 33 factorial design was selected for the present study and 17 runs were carried out in totality. The influence of various process variables (viz., polymer concentration, homogenization speed and sonication time) on the characteristics of nanoparticles including the in vitro drug release profile were studied. The nanoparticulate formulations were evaluated for mean spherical diameter, polydispersity index (PDI), zeta potential, surface morphology, drug entrapment and in-vitro drug release profile. The entrapment efficiency, drug loading and mean particle size were found to be 96.31±1.68 %, 35.46±0.35 % and 167.6±2.1 nm respectively. The investigated process and formulation variables were found to have significant effect on the particle size, drug loading (DL), entrapment efficiency (EE), and in vitro drug release profile. A biphasic in vitro drug release profile was apparent from the optimized nanoparticles (NPs) for 24 hours. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Experimental study on particulate and NOx emissions of a diesel engine fueled with ultra low sulfur diesel, RME-diesel blends and PME-diesel blends.

PubMed

Zhu, Lei; Zhang, Wugao; Liu, Wei; Huang, Zhen

2010-02-01

Ultra low sulfur diesel and two different kinds of biodiesel fuels blended with baseline diesel fuel in 5% and 20% v/v were tested in a Cummins 4BTA direct injection diesel engine, with a turbocharger and an intercooler. Experiments were conducted under five engine loads at two steady speeds (1500 rpm and 2500 rpm). The study aims at investigating the engine performance, NO(x) emission, smoke opacity, PM composition, PM size distribution and comparing the impacts of low sulfur content of biodiesel with ULSD on the particulate emission. The results indicate that, compared to base diesel fuel, the increase of biodiesel in blends could cause certain increase in both brake specific fuel consumption and brake thermal efficiency. Compared with baseline diesel fuel, the biodiesel blends bring about more NO(x) emissions. With the proportion of biodiesel increase in blends, the smoke opacity decreases, while total particle number concentration increases. Meanwhile the ULSD gives lower NO(x) emissions, smoke opacity and total number concentration than those of baseline diesel fuel. In addition, the percentages of SOF and sulfate in particulates increase with biodiesel in blends, while the dry soot friction decreases obviously. Compared with baseline diesel fuel, the biodiesel blends increase the total nucleation number concentration, while ULSD reduces the total nucleation number concentration effectively, although they all have lower sulfur content. It means that, for ULSD, the lower sulfur content is the dominant factor for suppressing nucleation particles formation, while for biodiesel blends, lower volatile, lower aromatic content and higher oxygen content of biodiesel are key factors for improving the nucleation particles formation. The results demonstrate that the higher NO(x) emission and total nucleation number concentration are considered as the big obstacles of the application of biodiesel in diesel engine. Copyright 2009 Elsevier B.V. All rights reserved.

Identification of dicarboxylic acids and aldehydes of PM10 and PM2.5 aerosols in Nanjing, China

NASA Astrophysics Data System (ADS)

Wang, Gehui; Niu, Sulian; Liu, Caie; Wang, Liansheng

In this study aerosol samples of PM10 and PM2.5 collected from 18 February 2001 to 1 May 2001 in Nanjing, China were analyzed for their water-soluble organic compounds. A series of homologous dicarboxylic acids (C 2-10) and two kinds of aldehydes (methylglyoxal and 2-oxo-malonaldehyde) were detected by GC and GC/MS. Among the identified compounds, the concentration of oxalic acid was the highest at all the five sites, which ranged from 178 to 1423 ng/m 3. The second highest concentration of dicarboxylic acids were malonic and succinic acids, which ranged from 26.9 to 243 ng/m 3. Higher level of azelaic acid was also observed, of which the maximum was 301 ng/m 3. As the highest fraction of dicarboxylic acids, oxalic acid comprised from 28% to 86% of total dicarboxylic acids in PM10 and from 41% to 65% of total dicarboxylic acids in PM2.5. The dicarboxylic acids (C 2, C 3, C 4) together accounted for 38-95% of total dicarboxylic acids in PM10 and 59-87% of dicarboxylic acids in PM2.5. In this study, the total dicarboxylic acids accounted for 2.8-7.9% of total organic carbon (TOC) of water-soluble matters for PM10 and 3.4-11.8% of TOC for PM2.5. All dicarboxylic acids detected in this study together accounted for about 1% of particle mass. The concentration of azelaic acid was higher at one site than others, which may be resulted from higher level of volatile fat used for cooking. The amounts of dicarboxyic acids (C 2,3,4,9) and 2-oxo-malonaldehyde of PM2.5 were higher in winter and lower in spring. Compared with other major metropolitans in the world, the level of oxalic acid concentration of Nanjing is much higher, which may be contributed to higher level of particle loadings, especially for fine particles.

Elucidating the impacts of initial supersaturation and seed crystal loading on struvite precipitation kinetics, fines production, and crystal growth.

PubMed

Agrawal, Shantanu; Guest, Jeremy S; Cusick, Roland D

2018-04-01

To reduce intra-plant nutrient cycling, and recover phosphorus (P) fertilizers from nutrient-rich sidestreams, wastewater utilities increasingly elect to employ struvite precipitation processes without a clear understanding of the inherent tradeoffs associated with specific design and operating decisions. Specifically, the impact of reactor conditions on struvite crystallization rate, and distribution between formation of fines particles and secondary growth onto large diameter seed crystals represent critical knowledge gaps limiting the predictive capabilities of existing process models. In this work, the relative impacts of initial supersaturation (S i ), and seed loading, on P removal kinetics, and struvite solids distribution were investigated. In experiments conducted at different levels of initial supersaturation (1.7-2.4) and seed loading (0-25 g L -1 ), struvite fines represented the majority of phosphate solids formed in 10 of 12 conditions. While total P removal was dependent on S i , and primarily attributed to formation of fines, the concentration of struvite seed granules had a significant impact on the rate of P removal. Struvite seed granules increased the rate of precipitation by reducing induction time of primary nucleation of struvite fines. Secondary crystal growth represented the majority of struvite solids formed at high seed loading and low S i , but presented the tradeoff of low total removal and low rate of removal. To convey the significance of these findings on process modeling, we show how a prominent kinetic model with a first-order dependency on solid struvite concentration over-predicts P removal rate when total mass is dominated by large diameter seeds (0.9 mm). This works reveals the critical role of struvite fines in P removal, and highlights the need to account for their production and kinetic importance in struvite process design and operation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Monitoring stream sediment loads in response to agriculture in Prince Edward Island, Canada.

PubMed

Alberto, Ashley; St-Hilaire, Andre; Courtenay, Simon C; van den Heuvel, Michael R

2016-07-01

Increased agricultural land use leads to accelerated erosion and deposition of fine sediment in surface water. Monitoring of suspended sediment yields has proven challenging due to the spatial and temporal variability of sediment loading. Reliable sediment yield calculations depend on accurate monitoring of these highly episodic sediment loading events. This study aims to quantify precipitation-induced loading of suspended sediments on Prince Edward Island, Canada. Turbidity is considered to be a reasonably accurate proxy for suspended sediment data. In this study, turbidity was used to monitor suspended sediment concentration (SSC) and was measured for 2 years (December 2012-2014) in three subwatersheds with varying degrees of agricultural land use ranging from 10 to 69 %. Comparison of three turbidity meter calibration methods, two using suspended streambed sediment and one using automated sampling during rainfall events, revealed that the use of SSC samples constructed from streambed sediment was not an accurate replacement for water column sampling during rainfall events for calibration. Different particle size distributions in the three rivers produced significant impacts on the calibration methods demonstrating the need for river-specific calibration. Rainfall-induced sediment loading was significantly greater in the most agriculturally impacted site only when the load per rainfall event was corrected for runoff volume (total flow minus baseflow), flow increase intensity (the slope between the start of a runoff event and the peak of the hydrograph), and season. Monitoring turbidity, in combination with sediment modeling, may offer the best option for management purposes.

Carbonaceous composition changes of heavy-duty diesel engine particles in relation to biodiesels, aftertreatments and engine loads.

PubMed

Cheng, Man-Ting; Chen, Hsun-Jung; Young, Li-Hao; Yang, Hsi-Hsien; Tsai, Ying I; Wang, Lin-Chi; Lu, Jau-Huai; Chen, Chung-Bang

2015-10-30

Three biodiesels and two aftertreatments were tested on a heavy-duty diesel engine under the US FTP transient cycle and additional four steady engine loads. The objective was to examine their effects on the gaseous and particulate emissions, with emphasis given to the organic and elemental carbon (OC and EC) in the total particulate matter. Negligible differences were observed between the low-sulfur (B1S50) and ultralow-sulfur (B1S10) biodiesels, whereas small reductions of OC were identified with the 10% biodiesel blend (B10). The use of diesel oxidation catalyst (DOC1) showed moderate reductions of EC and particularly OC, resulting in the OC/EC ratio well below unity. The use of DOC plus diesel particulate filter (DOC2+DPF) yielded substantial reductions of OC and particularly EC, resulting in the OC/EC ratio well above unity. The OC/EC ratios were substantially above unity at idle and low load, whereas below unity at medium and high load. The above changes in particulate OC and EC are discussed with respect to the fuel content, pollutant removal mechanisms and engine combustion conditions. Overall, the present study shows that the carbonaceous composition of PM could change drastically with engine load and aftertreatments, and to a lesser extent with the biodiesels under study. Copyright © 2015 Elsevier B.V. All rights reserved.

Fabrication of composite poly(d,l-lactide)/montmorillonite nanoparticles for controlled delivery of acetaminophen by solvent-displacement method using glass capillary microfluidics.

PubMed

Othman, Rahimah; Vladisavljević, Goran T; Thomas, Noreen L; Nagy, Zoltan K

2016-05-01

Paracetamol (PCM)-loaded composite nanoparticles (NPs) composed of a biodegradable poly(d,l-lactide) (PLA) polymer matrix filled with organically modified montmorillonite (MMT) nanoparticles were fabricated by antisolvent nanoprecipitation in a microfluidic co-flow glass capillary device. The incorporation of MMT in the polymer improved both the drug encapsulation efficiency and the drug loading, and extended the rate of drug release in simulated intestinal fluid (pH 7.4). The particle size increased on increasing both the drug loading and the concentration of MMT in the polymer matrix, and decreased on increasing the aqueous to organic flow rate ratio. The drug encapsulation efficiency in the NPs was higher at higher aqueous to organic flow rate ratio due to faster formation of the NPs. The PCM-loaded PLA NPs containing 2 wt% MMT in PLA prepared at an aqueous to organic flow rate ratio of 10 with an orifice size of 200 μm exhibited a spherical shape with a mean size of 296 nm, a drug encapsulation efficiency of 38.5% and a drug loading of 5.4%. The encapsulation of MMT and PCM in the NPs was confirmed by transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and attenuated total reflection-Fourier transform infrared spectroscopy. Copyright © 2016 Elsevier B.V. All rights reserved.

Distribution of pyrethroid insecticides in secondary wastewater effluent

PubMed Central

Parry, Emily; Young, Thomas M.

2014-01-01

Although the freely dissolved form of hydrophobic organic chemicals may best predict aquatic toxicity, differentiating between dissolved and particle bound forms is challenging at environmentally relevant concentrations for compounds with low toxicity thresholds such as pyrethroid insecticides. We investigated the distribution of pyrethroids among three forms: freely dissolved, complexed with dissolved organic carbon (DOC), and sorbed to suspended particulate matter, during a yearlong study at a secondary wastewater treatment plant. Effluent was fractionated by laboratory centrifugation to determine if sorption was driven by particle size. Linear distribution coefficients were estimated for pyrethroid sorption to suspended particulate matter (Kid) and dissolved organic carbon (Kidoc) at environmentally relevant pyrethroid concentrations. Resulting Kid values were higher than those reported for other environmental solids, and variation between sampling events correlated well with available particle surface area. Fractionation results suggest that no more than 40% of the pyrethroid remaining in secondary effluent could be removed by extending settling periods. Less than 6%of the total pyrethroid load in wastewater effluent was present in the dissolved form across all sampling events and chemicals. PMID:23939863

Granular controls on the dispersion of bed load tracers

NASA Astrophysics Data System (ADS)

Jerolmack, D. J.; Martin, R. L.; Phillips, C. B.

2014-12-01

Coarse particles are transported in a river as bed load, i.e., they move in frequent contact with and are supported by the granular bed. This movement is typically intermittent and may be described by a series of steps are rests, the distributions of which determine particle dispersion. Laboratory and field studies of bed load tracer dispersion have reported sub- and super-diffusive behavior, both of which have been successfully reproduced with stochastic transport models. Although researchers have invoked heavy-tailed step lengths as the cause of anomalous dispersion, most observations report thin-tailed distributions. Little attention has been paid to rest periods, and stochastic transport models have not been connected to the underlying mechanics of particle motion. Based on theoretical and experimental evidence, we argue that step lengths are thin-tailed and do not control the longterm dispersion of bed load tracers; they are determined by momentum balance between the fluid and solid. Using laboratory experiments with both marbles and natural sediments, we demonstrate that the rest time distribution is power law, and argue that this distribution controls asymptotic dispersion. Observed rest times far exceed any hydrodynamic timescale. Experiments reveal that rest times of deposited particles are governed by fluctuations in river bed elevation; in particular, the return time for the bed to scour to the base of a deposited particle. Stochastic fluctuations in bed elevation are describable by an Ornstein-Uhlenbeck (mean-reverting random walk) model that contains two parameters, which we show are directly related to the granular shear rate and range of bed elevation fluctuations, respectively. Combining these results with the theory of asymmetric random walks (particles only move downstream), we predict superdiffusive behavior that is in quantitative agreement with our observations of tracer dispersion in a natural river.

Load application for the contact mechanics analysis and wear prediction of total knee replacement.

PubMed

Zhang, Jing; Chen, Zhenxian; Wang, Ling; Li, Dichen; Jin, Zhongmin

2017-05-01

Tibiofemoral contact forces in total knee replacement have been measured at the medial and lateral sites respectively using an instrumented prosthesis, and predicted from musculoskeletal multibody dynamics models with a reasonable accuracy. However, it is uncommon that the medial and lateral forces are applied separately to replace a total axial load according to the ISO standard in the majority of current finite element analyses. In this study, we quantified the different effects of applying the medial and lateral loads separately versus the traditional total axial load application on contact mechanics and wear prediction of a patient-specific knee prosthesis. The load application position played an important role under the medial-lateral load application. The loading set which produced the closest load distribution to the multibody dynamics model was used to predict the contact mechanics and wear for the prosthesis and compared with the total axial load application. The medial-lateral load distribution using the present method was found to be closer to the multibody dynamics prediction than the traditional total axial load application, and the maximum contact pressure and contact area were consistent with the corresponding load variation. The predicted total volumetric wear rate and area were similar between the two load applications. However, the split of the predicted wear volumes on the medial and the lateral sides was different. The lateral volumetric wear rate was 31.46% smaller than the medial from the traditional load application prediction, while from the medial-lateral load application, the lateral side was only 11.8% smaller than the medial. The medial-lateral load application could provide a new and more accurate method of load application for patient-specific preclinical contact mechanics and wear prediction of knee implants.

Hybrid optimal online-overnight charging coordination of plug-in electric vehicles in smart grid

NASA Astrophysics Data System (ADS)

Masoum, Mohammad A. S.; Nabavi, Seyed M. H.

2016-10-01

Optimal coordinated charging of plugged-in electric vehicles (PEVs) in smart grid (SG) can be beneficial for both consumers and utilities. This paper proposes a hybrid optimal online followed by overnight charging coordination of high and low priority PEVs using discrete particle swarm optimization (DPSO) that considers the benefits of both consumers and electric utilities. Objective functions are online minimization of total cost (associated with grid losses and energy generation) and overnight valley filling through minimization of the total load levels. The constraints include substation transformer loading, node voltage regulations and the requested final battery state of charge levels (SOCreq). The main challenge is optimal selection of the overnight starting time (toptimal-overnight,start) to guarantee charging of all vehicle batteries to the SOCreq levels before the requested plug-out times (treq) which is done by simultaneously solving the online and overnight objective functions. The online-overnight PEV coordination approach is implemented on a 449-node SG; results are compared for uncoordinated and coordinated battery charging as well as a modified strategy using cost minimizations for both online and overnight coordination. The impact of toptimal-overnight,start on performance of the proposed PEV coordination is investigated.

Liposome-based mucus-penetrating particles (MPP) for mucosal theranostics: demonstration of diamagnetic chemical exchange saturation transfer (diaCEST) magnetic resonance imaging (MRI).

PubMed

Yu, Tao; Chan, Kannie W Y; Anonuevo, Abraham; Song, Xiaolei; Schuster, Benjamin S; Chattopadhyay, Sumon; Xu, Qingguo; Oskolkov, Nikita; Patel, Himatkumar; Ensign, Laura M; van Zjil, Peter C M; McMahon, Michael T; Hanes, Justin

2015-02-01

Mucus barriers lining mucosal epithelia reduce the effectiveness of nanocarrier-based mucosal drug delivery and imaging ("theranostics"). Here, we describe liposome-based mucus-penetrating particles (MPP) capable of loading hydrophilic agents, e.g., the diaCEST MRI contrast agent barbituric acid (BA). We observed that polyethylene glycol (PEG)-coated liposomes containing ≥7 mol% PEG diffused only ~10-fold slower in human cervicovaginal mucus (CVM) compared to their theoretical speeds in water. 7 mol%-PEG liposomes contained sufficient BA loading for diaCEST contrast, and provided improved vaginal distribution compared to 0 and 3mol%-PEG liposomes. However, increasing PEG content to ~12 mol% compromised BA loading and vaginal distribution, suggesting that PEG content must be optimized to maintain drug loading and stability. Non-invasive diaCEST MRI illustrated uniform vaginal coverage and longer retention of BA-loaded 7 mol%-PEG liposomes compared to unencapsulated BA. Liposomal MPP with optimized PEG content hold promise for drug delivery and imaging at mucosal surfaces. This team of authors characterized liposome-based mucus-penetrating particles (MPP) capable of loading hydrophilic agents, such as barbituric acid (a diaCEST MRI contrast agent) and concluded that liposomal MPP with optimized PEG coating enables drug delivery and imaging at mucosal surfaces. Copyright © 2015 Elsevier Inc. All rights reserved.

Controlled release of NELL-1 protein from chitosan/hydroxyapatite-modified TCP particles.

PubMed

Zhang, Yulong; Dong, Rui; Park, Yujin; Bohner, Marc; Zhang, Xinli; Ting, Kang; Soo, Chia; Wu, Benjamin M

2016-09-10

NEL-like molecule-1 (NELL-1) is a novel osteogenic protein that showing high specificity to osteochondral cells. It was widely used in bone regeneration research by loading onto carriers such as tricalcium phosphate (TCP) particles. However, there has been little research on protein controlled release from this material and its potential application. In this study, TCP was first modified with a hydroxyapatite coating followed by a chitosan coating to prepare chitosan/hydroxyapatite-coated TCP particles (Chi/HA-TCP). The preparation was characterized by SEM, EDX, FTIR, XRD, FM and Zeta potential measurements. The NELL-1 loaded Chi/HA-TCP particles and the release kinetics were investigated in vitro. It was observed that the Chi/HA-TCP particles prepared with the 0.3% (wt/wt) chitosan solution were able to successfully control the release of NELL-1 and maintain a slow, steady release for up to 28 days. Furthermore, more than 78% of the loaded protein's bioactivity was preserved in Chi/HA-TCP particles over the period of the investigation, which was significantly higher than that of the protein released from hydroxyapatite coated TCP (HA-TCP) particles. Collectively, this study suggests that the osteogenic protein NELL-1 showed a sustained release pattern after being encapsulated into the modified Chi/HA-TCP particles, and the NELL-1 integrated composite of Chi/HA-TCP showed a potential to function as a protein delivery carrier and as an improved bone matrix for use in bone regeneration research. Copyright © 2016 Elsevier B.V. All rights reserved.

On Characterizing Particle Shape

NASA Technical Reports Server (NTRS)

Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

2014-01-01

It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.

Silk sericin loaded alginate nanoparticles: Preparation and anti-inflammatory efficacy.

PubMed

Khampieng, Thitikan; Aramwit, Pornanong; Supaphol, Pitt

2015-09-01

In this study, silk sericin loaded alginate nanoparticles were prepared by the emulsification method followed by internal crosslinking. The effects of various silk sericin loading concentration on particle size, shape, thermal properties, and release characteristics were investigated. The initial silk sericin loadings of 20, 40, and 80% w/w to polymer were incorporated into these alginate nanoparticles. SEM images showed a spherical shape and small particles of about 71.30-89.50 nm. TGA analysis showed that thermal stability slightly increased with increasing silk sericin loadings. FTIR analysis suggested interactions between alginate and silk sericin in the nanoparticles. The release study was performed in acetate buffer at normal skin conditions (pH 5.5; 32 °C). The release profiles of silk sericin exhibited initial rapid release, consequently with sustained release. These silk sericin loaded alginate nanoparticles were further incorporated into topical hydrogel and their anti-inflammatory properties were studied using carrageenan-induced paw edema assay. The current study confirms the hypothesis that the application of silk sericin loaded alginate nanoparticle gel can inhibit inflammation induced by carrageenan. Copyright © 2015 Elsevier B.V. All rights reserved.

Biopharmaceutical characterisation of insulin and recombinant human growth hormone loaded lipid submicron particles produced by supercritical gas micro-atomisation.

PubMed

Salmaso, Stefano; Bersani, Sara; Elvassore, Nicola; Bertucco, Alberto; Caliceti, Paolo

2009-09-08

Homogeneous dispersions of insulin and recombinant human growth hormone (rh-GH) in tristearin/phosphatidylcholine/PEG mixtures (1.3:1.3:0.25:0.15 w/w ratio) were processed by supercritical carbon dioxide gas micro-atomisation to produce protein-loaded lipid particles. The process yielded spherical particles, with a 197+/-94 nm mean diameter, and the insulin and rh-GH recovery in the final product was 57+/-8% and 48+/-5%, respectively. In vitro, the proteins were slowly released for about 70-80 h according to a diffusive mechanism. In vivo, the insulin and glucose profiles in plasma obtained by subcutaneous administration of a dose of particles containing 2 microg insulin to diabetic mice overlapped that obtained with 2 microg of insulin in solution. Administration of a dose of particles containing 5 microg insulin resulted in faster and longer glycaemia reduction. Oral administration of 20 and 50 microg insulin equivalent particles produced a significant hypoglycaemic effect. The glucose levels decreased since 2h after administration, reaching about 50% and 70% glucose reduction in 1-2h with the lower and higher dose, respectively. As compared to subcutaneous administration, the relative pharmacological bioavailability obtained with 20 and 50 microg equivalent insulin particles was 7.7% and 6.7%, respectively. Daily subcutaneous administration of 40 microg of rh-GH-loaded particles to hypophysectomised rats induced similar body weight increase as 40 microg rh-GH in solution. The daily oral administration of 400 microg rh-GH equivalent particles elicited a slight body weight increase, which corresponded to a relative pharmacological bioavailability of 3.4% compared to subcutaneous administration.

Design and characterization of sustained release ketoprofen entrapped carnauba wax microparticles.

PubMed

Oliveira, Rodinelli B; Nascimento, Thais L; Lima, Eliana M

2012-01-01

Ketoprofen is a non-steroid anti-inflammatory drug (NSAID) used in the treatment of rheumatic diseases and in mild to moderate pain. Ketoprofen has a short biological half-life and the commercially available conventional release formulations require dosages to be administered at least 2-3 times a day. Due to these characteristics, ketoprofen is a good candidate for the preparation of controlled release formulations. In this work, a multiparticulate-sustained release dosage form containing ketoprofen in a carnauba wax matrix was developed. Particles were prepared by an emulsion congealing technique. System variables were optimized using fractional factorial and response surface experimental design. Characterization of the particles included size and morphology, flow rate, drug loading and in vitro drug release. Spherical particles were obtained with high drug load and sustained drug release profile. The optimized particles had an average diameter of approximately 200 µm, 50% (w/w) drug load, good flow properties and prolonged ketoprofen release for more than 24 h. Carnauba wax microspheres prepared in this work represent a new multiparticulate-sustained release system for the NSAID ketoprofen, exhibiting good potential for application in further pharmaceutical processes.

Aerosol properties over the western Mediterranean basin: temporal and spatial variability

NASA Astrophysics Data System (ADS)

Lyamani, H.; Valenzuela, A.; Perez-Ramirez, D.; Toledano, C.; Granados-Muñoz, M. J.; Olmo, F. J.; Alados-Arboledas, L.

2015-03-01

This study focuses on the analysis of Aerosol Robotic Network (AERONET) aerosol data obtained over Alborán Island (35.90° N, 3.03° W, 15 m a.s.l.) in the western Mediterranean from July 2011 to January 2012. Additional aerosol data from the three nearest AERONET stations (Málaga, Oujda and Palma de Mallorca) and the Maritime Aerosol Network (MAN) were also analyzed in order to investigate the temporal and spatial variations of aerosol over this scarcely explored region. High aerosol loads over Alborán were mainly associated with desert dust transport from North Africa and occasional advection of anthropogenic fine particles from central European urban-industrial areas. The fine particle load observed over Alborán was surprisingly similar to that obtained over the other three nearest AERONET stations, suggesting homogeneous spatial distribution of fine particle loads over the four studied sites in spite of the large differences in local sources. The results from MAN acquired over the Mediterranean Sea, Black Sea and Atlantic Ocean from July to November 2011 revealed a pronounced predominance of fine particles during the cruise period.

Understanding transport pathways in a river system - Monitoring sediments contaminated by an incident

NASA Astrophysics Data System (ADS)

Dietrich, S.; Kleisinger, C.; Hillebrand, G.; Claus, E.; Schwartz, R.; Carls, I.; Winterscheid, A.; Schubert, B.

2016-12-01

Experiments to trace transport of sediments and suspended particulate matter on a river scale are an expensive and difficult venture, since it causes a lot of official requirements. In spring 2015, polychlorinated biphenyls (PCB) were released during restoration works at a bridge in the upper part of the Elbe River, near the Czech-German border. In this study, the particle-bound PCB-transport is applied as a tracer for monitoring transport pathways of suspended solids (SS) along a whole river stretch over 700 km length. The incident was monitored by concentration measurements of seven indicator PCB congeners along the inland part of the Elbe River as well as in the Elbe estuary. Data from 15 monitoring stations (settling tanks) as well as from two longitudinal campaigns (grab samples) along the river in July and August 2015 are considered. The total PCB load is calculated for all stations on the basis of monthly contaminant concentrations and daily suspended sediment concentrations. Monte-Carlo simulations assess the uncertainties of the calculated load. 1D water levels and GIS analysis were used to locate temporal storage areas for the SS. It is shown that the ratio of high versus low chlorinated PCB congeners is a suitable tracer to distinguish the PCB load of the incident from the long-term background signal. Furthermore, the reduction of total PCB load within the upper Elbe indicates that roughly 24% of the SS were transported with the water by wash load. Approximately 600 km downstream of the incident site, the PCB-marked wash load was first identified in July 2015. PCB load transported intermittently in suspension was detected roughly 400 km downstream of the incident site by August 2015. In the Elbe Estuary, PCB-marked SS were only found upstream of the steep slope of water depth (approx. 4 to 15 m) within Hamburg harbor that acts as a major sediment sink. Here, SS from the inland Elbe are mixed with lowly contaminated marine material, which may mask the effect of the PCB release.

Mechanics of load-drag-unload contact cleaning of gecko-inspired fibrillar adhesives.

PubMed

Abusomwan, Uyiosa A; Sitti, Metin

2014-10-14

Contact self-cleaning of gecko-inspired synthetic adhesives with mushroom-shaped tips has been demonstrated recently using load-drag-unload cleaning procedures similar to that of the natural animal. However, the underlying mechanics of contact cleaning has yet to be fully understood. In this work, we present a detailed experiment of contact self-cleaning that shows that rolling is the dominant mechanism of cleaning for spherical microparticle contaminants, during the load-drag-unload procedure. We also study the effect of dragging rate and normal load on the particle rolling friction. A model of spherical particle rolling on an elastomer fibrillar adhesive interface is developed and agrees well with the experimental results. This study takes us closer to determining design parameters for achieving self-cleaning fibrillar adhesives.

Decoupling the Role of Particle Inertia and Gravity on Particle Dispersion

NASA Technical Reports Server (NTRS)

Squires, Kyle D.

2002-01-01

Particle dispersion and the influence that particle momentum exchange has on the properties of a turbulent carrier flow in micro-gravity environments challenge present understanding and predictive schemes. The objective of this effort has been to develop and assess high-fidelity simulation tools for predicting particle transport within micro-gravity environments suspended in turbulent flows. The computational technique is based on Direct Numerical Simulation (DNS) of the incompressible Navier-Stokes equations. The particular focus of the present work is on the class of dilute flows in which particle volume fractions and inter-particle collisions are negligible. Particle motion is assumed to be governed by drag with particle relaxation times ranging from the Kolmogorov scale to the Eulerian timescale of the turbulence and particle mass loadings up to one. The velocity field was made statistically stationary by forcing the low wavenumbers of the flow. The calculations were performed using 96(exp 3) collocation points and the Taylor-scale Reynolds number for the stationary flow was 62. The effect of particles on the turbulence was included in the Navier-Stokes equations using the point-force approximation in which 96(exp 3) particles were used in the calculations. DNS results show that particles increasingly dissipate fluid kinetic energy with increased loading, with the reduction in kinetic energy being relatively independent of the particle relaxation time. Viscous dissipation in the fluid decreases with increased loading and is larger for particles with smaller relaxation times. Fluid energy spectra show that there is a non-uniform distortion of the turbulence with a relative increase in small-scale energy. The non-uniform distortion significantly affects the transport of the dissipation rate, with the production and destruction of dissipation exhibiting completely different behaviors. The spectrum of the fluid-particle energy exchange rate shows that the fluid drags particles at low wavenumbers while the converse is true at high wavenumbers for small particles. A spectral analysis shows that the increase of the high wavenumber portion of the fluid energy spectrum can be attributed to transfer of the fluid-particle covariance by the fluid turbulence. This in turn explains the relative increase of small-scale energy caused by small particles observed in the present simulations as well as those of others.

Melt spinning of poly(lactic acid) and hydroxyapatite composite fibers: influence of the filler content on the fiber properties.

PubMed

Persson, Maria; Lorite, Gabriela S; Cho, Sung-Woo; Tuukkanen, Juha; Skrifvars, Mikael

2013-08-14

Composite fibers from poly(lactic acid) (PLA) and hydroxyapatite (HA) particles were prepared using melt spinning. Different loading concentrations of HA particles (i.e., 5, 10, 15, and 20 wt %) in the PLA fibers and solid-state draw ratios (SSDRs) were evaluated in order to investigate their influence on the fibers' morphology and thermal and mechanical properties. A scanning electron microscopy investigation indicated that the HA particles were homogeneously distributed in the PLA fibers. It was also revealed by atomic force microscopy and Fourier transform infrared spectroscopy that HA particles were located on the fiber surface, which is of importance for their intended application in biomedical textiles. Our results also suggest that the mechanical properties were independent of the loading concentration of the HA particles and that the SSDR played an important role in improving the mechanical properties of the composite fibers.

Effects of preferential concentration on direct radiation transmission in a turbulent duct flow

NASA Astrophysics Data System (ADS)

Villafane, Laura; Banko, Andrew; Kim, Ji Hoon; Elkins, Chris; Eaton, John

2017-11-01

Inertial particles in turbulent flows preferentially concentrate, giving rise to spatial and temporal fluctuations of particle number density that affect radiation transmission through the medium. Positive particle correlations enhance direct transmission when compared to the exponential attenuation predicted by the Beer's Law for randomly distributed particles. In the context of a particle based solar receiver, this work studies the effects of preferential concentration and optical depth on direct transmission through a particle laden turbulent duct flow. Time resolved measurements of transmission through the mixture were performed for various particle loadings and Reynolds numbers, thus varying particle correlation lengths, optical depth and concentration fluctuations. These measurements were made using a photodiode to record the transmission of a collimated laser beam along the wall bisector of the duct. A synchronized high-speed camera provided particle positions along most of the beam path. Average and fluctuating radiation transmission results are compared to predictions derived from the imaged number density fields and to simplified analytical models. Simplified models are able to capture the correct trends with varying loading and preferential concentration. This work is funded by the Department of Energy's National Nuclear Security Administration, Grant #DE-NA0002373-1.

[Preparation of ibuprofen/EC-PVP sustained-release composite particles by supercritical CO2 anti-solvent technology].

PubMed

Cai, Jin-Yuan; Huang, De-Chun; Wang, Zhi-Xiang; Dang, Bei-Lei; Wang, Qiu-Ling; Su, Xin-Guang

2012-06-01

Ibuprofen/ethyl-cellulose (EC)-polyvinylpyrrolidone (PVP) sustained-release composite particles were prepared by using supercritical CO2 anti-solvent technology. With drug loading as the main evaluation index, orthogonal experimental design was used to optimize the preparation process of EC-PVP/ibuprofen composite particles. The experiments such as encapsulation efficiency, particle size distribution, electron microscope analysis, infrared spectrum (IR), differential scanning calorimetry (DSC) and in vitro dissolution were used to analyze the optimal process combination. The orthogonal experimental optimization process conditions were set as follows: crystallization temperature 40 degrees C, crystallization pressure 12 MPa, PVP concentration 4 mgmL(-1), and CO2 velocity 3.5 Lmin(-1). Under the optimal conditions, the drug loading and encapsulation efficiency of ibuprofen/EC-PVP composite particles were 12.14% and 52.21%, and the average particle size of the particles was 27.621 microm. IR and DSC analysis showed that PVP might complex with EC. The experiments of in vitro dissolution showed that ibuprofen/EC-PVP composite particles had good sustained-release effect. Experiment results showed that, ibuprofen/EC-PVP sustained-release composite particles can be prepared by supercritical CO2 anti-solvent technology.

[Effect analysis on the two total load control methods for poisonous heavy metals].

PubMed

Fu, Guo-Wei

2012-12-01

Firstly it should be made clear that implementation of source total load control for the first type of pollutants is necessary for environmental pollution control legislation and economic structure regulation. This kind of surveillance method has been more practical to be implemented since the Manual of the Industry Discharge Coefficient of First National Pollution Sources Investigation was published. The source total load control and water environment total load control are independent of each other and none of them is redundant, on the other side they can be complementary to each other. In the present, some local planning managers are blurring and confusing the contents and styles of the two surveillance methods. They just use the water total load control to manage all the pollutants, and source total load control is discarded, which results in the loss of control for the first type of pollutants especially for the drinking water source surveillance. There is a big difference between the water quality standards and the water environmental background concentration values for the first type of pollutants in the Environmental quality standard for surface water (GB 3838-88), which means that there are problems such as "relaxing the pollutant discharge permit" and "risk induced by valence state change". Taking an enterprise with 10t electrolytic lead production capacity as an example, there is a big difference between the allowable lead discharged loads by the two total load surveillance methods. In summary, it will bring a lot of harmful effects if the water total load control is implemented for the two types of pollutants, so the source total load control and water environmental total load control should be implemented strictly at the same time.

Solid-loaded flows: applications in technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molerus, O.

1983-01-01

The evaluation of experiments and the representation of the resulting data by nondimensional groups defined ad hoc largely governs the treatment of problems arising with solid-loaded flows in practice. Without doubt, this is a result of the very complex nature of solid-loaded flows and, consequently, empiricism tends to prevail, more or less. To overcome this situation, two sets of nondimensional groups, which take into consideration the translatory, as well as the rotary, motion of particles suspended in a fluid, are derived from the equations of motion of a solid body. The intuitive meaning of these nondimensional groups arises from theirmore » derivation. With respect to applications in engineering, the influence of the rotary motion of a particle on the motion of its center of gravity can thus be taken into account. As such, a common basis for the representation of the different phenomena observed with solid-loaded flows is established. The application of the above concepts to fluidization and hydraulic and pneumatic conveying proves their usefulness. New insights into well-known facts as well as new results demonstrate that taking the real nature of solid particles (i.e., those of finite dimensions) into consideration will provide a common and profound basis for the representation of different phenomena observed with solid-loaded flows in practice.« less

An implementation of particle swarm optimization to evaluate optimal under-voltage load shedding in competitive electricity markets

NASA Astrophysics Data System (ADS)

Hosseini-Bioki, M. M.; Rashidinejad, M.; Abdollahi, A.

2013-11-01

Load shedding is a crucial issue in power systems especially under restructured electricity environment. Market-driven load shedding in reregulated power systems associated with security as well as reliability is investigated in this paper. A technoeconomic multi-objective function is introduced to reveal an optimal load shedding scheme considering maximum social welfare. The proposed optimization problem includes maximum GENCOs and loads' profits as well as maximum loadability limit under normal and contingency conditions. Particle swarm optimization (PSO) as a heuristic optimization technique, is utilized to find an optimal load shedding scheme. In a market-driven structure, generators offer their bidding blocks while the dispatchable loads will bid their price-responsive demands. An independent system operator (ISO) derives a market clearing price (MCP) while rescheduling the amount of generating power in both pre-contingency and post-contingency conditions. The proposed methodology is developed on a 3-bus system and then is applied to a modified IEEE 30-bus test system. The obtained results show the effectiveness of the proposed methodology in implementing the optimal load shedding satisfying social welfare by maintaining voltage stability margin (VSM) through technoeconomic analyses.

Preparation and characterization of Pt loaded WO3 films suitable for gas sensing applications

NASA Astrophysics Data System (ADS)

Jolly Bose, R.; Illyasukutty, Navas; Tan, K. S.; Rawat, R. S.; Vadakke Matham, Murukesan; Kohler, Heinz; Mahadevan Pillai, V. P.

2018-05-01

This paper presents the preparation of nanostructured platinum (Pt) loaded tungsten oxide (WO3) thin films by radio frequency (RF) magnetron sputtering technique. Even though, Pt loading does not produce any phase change in WO3 lattice, it deteriorates the crystalline quality and induces defects on WO3 films. The Pt loading in WO3 has profound impact on structural and optical properties of the films by which the particle size, lattice strain and optical band gap energy are reduced. Nanoporous film with reduced particle size is obtained for 5 wt% Pt loaded WO3 sample which is crucial for gas sensors. Hence the sensing response of 5 wt% Pt loaded sample is tested towards carbon monoxide (CO) gas along with pure WO3 sample. The sensing response of Pt loaded sample is nearly 15 times higher than pure WO3 sample in non-humid ambience at an operating temperature 200 °C. This indicates the suitability of the prepared films for gas sensors. The sensing response of pure WO3 film depends on the humidity while the Pt loaded WO3 film shows stable response in both humid and non-humid ambiences.

Improved Antitumor Efficacy and Pharmacokinetics of Bufalin via PEGylated Liposomes

NASA Astrophysics Data System (ADS)

Yuan, Jiani; Zhou, Xuanxuan; Cao, Wei; Bi, Linlin; Zhang, Yifang; Yang, Qian; Wang, Siwang

2017-11-01

Bufalin was reported to show strong pharmacological effects including cardiotonic, antiviral, immune-regulation, and especially antitumor effects. The objective of this study was to determine the characterization, antitumor efficacy, and pharmacokinetics of bufalin-loaded PEGylated liposomes compared with bufalin entity, which were prepared by FDA-approved pharmaceutical excipients. Bufalin-loaded PEGylated liposomes and bufalin-loaded liposomes were prepared reproducibly with homogeneous particle size by the combination of thin film evaporation method and high-pressure homogenization method. Their mean particle sizes were 127.6 and 155.0 nm, mean zeta potentials were 2.24 and - 18.5 mV, and entrapment efficiencies were 76.31 and 78.40%, respectively. In vitro release profile revealed that the release of bufalin in bufalin-loaded PEGylated liposomes was slower than that in bufalin-loaded liposomes. The cytotoxicity of blank liposomes has been found within acceptable range, whereas bufalin-loaded PEGylated liposomes showed enhanced cytotoxicity to U251 cells compared with bufalin entity. In vivo pharmacokinetics indicated that bufalin-loaded PEGylated liposomes could extend or eliminate the half-life time of bufalin in plasma in rats. The results suggested that bufalin-loaded PEGylated liposomes improved the solubility and increased the drug concentration in plasma.

Evaluation of the filler packing structures in dental resin composites: From theory to practice.

PubMed

Wang, Ruili; Habib, Eric; Zhu, X X

2018-07-01

The aim of this study is to evaluate the packing properties of uniform silica particles and their mixture with secondary particles yielding maximally loaded dental composites. We intend to verify the difference between the idealized models (the close-packed structures and the random-packed structures) and the actual experimental results, in order to provide guidance for the preparation of dental composites. The influence of secondary particle size and the resin composition on the physical-mechanical properties and the rheological properties of the experimental dental composites was also investigated. Silica particles (S-920, S-360, and S-195) with average diameters of 920, 360, and 195nm were synthesized via the Stöber process. Their morphology and size distribution were determined by field-emission scanning electron microscopy and laser particle sizer. A series of silica fillers, S-920, S-920+195, S-920+360, and S-920+360+195, were then formulated with two Bis-GMA/TEGDMA resins (weight ratios of 70:30 and 50:50). For these experimental dental composites, their maximum filler loadings were assessed and compared to the theory. The mechanical properties, degree of conversion, depth of cure, and polymerization shrinkage of these composites were then evaluated. Their rheological behaviors were measured with a rheometer. Unimodal S-920 had the maximally filler loading of 70.80wt% with the 5B5T resin, close to the theoretical estimation of the random loose packing (71.92wt%). The maximum loading of the S-920+360+195 filled composite was 72.92wt% for the same resin, compared to the theoretical estimation of 89.29wt% obtained for the close-packed structures. These findings indicate that random loose packing matches more closely to the real packing state for the filler formulations used. When maximally loaded, the composite with S-920+360+195 produced the best mechanical properties and the lowest polymerization shrinkage. The degree of conversion and depth of cure were higher with secondary particles added, and the viscosity of all unpolymerized pastes exhibited shear thinning behavior. Theoretical estimations of filler packing structures provide a useful guidance in the design of multimodal filler formulations and the preparation of dental composites with higher filler loading, improved physical-mechanical properties. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Evaluation of columns packed with shell particles with compounds of pharmaceutical interest.

PubMed

Ruta, Joséphine; Zurlino, Daria; Grivel, Candice; Heinisch, Sabine; Veuthey, Jean-Luc; Guillarme, Davy

2012-03-09

The commercial C18 columns packed with sub-3 μm shell particles were tested and compared to a reference UHPLC column, in terms of kinetic performance as well as selectivity, retention capability, peak shape and loading capacity. For this purpose, a set of pharmaceutically relevant molecules was selected, including acidic, neutral and basic drugs. Regarding kinetic performance, h(opt) values for the shell particles were found between 1.7 and 2, while the UHPLC column provided a value of approximately 2.5. However, this impressive performance should be considered with caution, particularly for the construction of kinetic plots since h(opt) values were sometimes related to the column dimensions, depending on the provider (h(opt) comprised between 1.8 and 2.6 for longer columns of 150 mm packed with shell particles). Despite the non-porous inner core of the shell particles representing between 25 and 36% of the particle, we demonstrated that the decrease in retention was on the maximum equal to 15% for Ascentis column while Acquity and Poroshell were strictly equivalent in terms of retention. Concerning loading capacity, it remains comparable to that of fully porous sub-2 μm particles and always more pronounced with 0.1% formic acid vs. phosphate buffer. The loading capacity of the different columns was found to be better correlated to the pore volume or surface coverage than the shell thickness. Experimentally, the most pronounced overloading was observed with the Poroshell. Finally, the selectivity and peak shape were evaluated using a mixture of basic and acidic drugs. It appears that results were very similar between sub-3 μm shell particles and fully porous sub-2-μm particles for our mixture of compounds, showing the ability to transfer existing methods to shell particles, with only limited adjustments. This study confirms the potential of columns packed with shell particles and demonstrates the interest of such column technology with pharmaceutical compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

Application of close-packed structures in dental resin composites.

PubMed

Wang, Ruili; Habib, Eric; Zhu, X X

2017-03-01

The inorganic filler particles in dental resin composites serve to improve their mechanical properties and reduce polymerization shrinkage during their use. Efforts have been made in academia and industry to increase the filler particle content, but, few studies examine the theoretical basis for the maximum particle loading. This work evaluates the packing of spherical particles in a close-packed state for highly loaded composites. Calculations show that for low dispersity particles, the maximum amount of particles is 74.05vol%, regardless of the particle size. This can be further improved by using a mix of large and small particles or by the use of non-spherical particles. For representative spherical particles with a diameter of 1000nm, two types of secondary particles with respective sizes of 414nm (d I ) and 225nm (d II ) are selected. The results show that after embedding secondary particles I & II into primary spherical particles, the packing factor is increased to 81.19% for the close-packed structures, which shows an improvement of 9.64%, compared to the 74.05% obtained only with primary spherical particles. This packing factor is also higher than either structure with the embedded secondary particles I or II. Examples of these mixtures with different spherical particle sizes are shown as a theoretical estimation, serving as a guideline for the design and formulation of new dental resin composites with better properties and improved performance. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Near-infrared mediated quantum dots and paclitaxel co-loaded nanostructured lipid carriers for cancer theragnostic.

PubMed

Olerile, Livesey David; Liu, Yongjun; Zhang, Bo; Wang, Tianqi; Mu, Shengjun; Zhang, Jing; Selotlegeng, Lesego; Zhang, Na

2017-02-01

Timing is an important factor in cancer management. Theragnostic systems have benefit of improving patients' life-quality by expediting therapeutic decisions. The objective of this study was to explore the potential of co-loaded [quantum dots (CdTe/CdS/ZnS) and paclitaxel] NLC (nanostructured lipid carriers) as a parenteral multifunctional delivery system. The co-loaded NLC was prepared by emulsion-evaporation and low temperature-solidification method utilising glyceryl monostearate, oleic acid, and soya phosphatidylcholine as lipid matrix. In characterising the co-loaded NLC, physicochemical properties of particle size, polydispersity index (PDI), zeta potential (ZP), morphology, encapsulation efficacy (EE) and drug loading (DL) were investigated. Moreover, in-vitro paclitaxel release profile, cytotoxicity, histopathological, in-vivo anti-tumour efficacy, and in-vivo and ex-vivo fluorescence optical imaging abilities of the co-loaded NLC were assessed. The mean particle size, PDI and ZP were reported to be 115.93±1.61nm, 0.17±0.04 and -0.22±0.03mV, respectively. The particles were spheroid-like in shape with relatively smooth surface. A higher EE (80.70±2.11%) and DL (4.68±0.04%) were recorded. The coloaded NLC exhibited a biphasic pattern of drug release. IC 50 value was found to be 1.05±0.58μM. The tumour growth inhibition rate of 77.85% was registered. The in-vivo and ex-vivo imaging results indicated capability of the co-loaded NLC to specifically target and detect the H22 tumour. Tissues showed no significant cytoarchitectural differences. We can satisfactorily conclude that co-loaded NLC formulation can be qualified as a splendid parenteral drug delivery system foundation for cancer theragnostic. Copyright © 2016 Elsevier B.V. All rights reserved.

Elastohydrodynamic lubrication in point contact on the surfaces of particle-reinforced composite

NASA Astrophysics Data System (ADS)

Chen, Keying; Zeng, Liangcai; Wu, Zhenpeng; Zheng, Feilong

2018-04-01

Appreciable friction and serious wear are common challenges in the operation of advanced manufacturing equipment, and friction pairs may be susceptible to damage even with oil lubrication when point contact exists. In this study, a type of particle-reinforced composite material is introduced for one of the components of a heavy-load contact pair, and the performance improvement of elastohydrodynamic lubrication (EHL) is analyzed considering the rheological properties of non-Newtonian fluids. The Ree-Eyring EHL model is used considering the surface of the particle-reinforced composite, in which the film thickness includes the particle-induced elastic deformation. The problem of inclusions with different eigenstrains is solved by using Galerkin vectors. The influences of particle properties, size, burial depth, and interparticle distance on point-contact EHL are investigated. Furthermore, using several cases, the structural parameters of the particles in the composites are optimized, and an appropriate parameter range is obtained with the goal of reducing friction. Finally, the results for the EHL traction coefficient demonstrate that appropriate particle properties, size, burial depth, and interparticle distance can effectively reduce the traction coefficient in heavy-load contact.

Low Molecular Weight Glucosamine/L-lactide Copolymers as Potential Carriers for the Development of a Sustained Rifampicin Release System: Mycobacterium Smegmatis as a Tuberculosis Model

NASA Astrophysics Data System (ADS)

Ragusa, Jorge Alejandro

Tuberculosis, a highly contagious disease, ranks as the second leading cause of death from an infectious disease, and remains a major global health problem. In 2013, 9 million new cases were diagnosed and 1.5 million people died worldwide from tuberculosis. This dissertation aims at developing a new, ultrafine particle-based efficient antibiotic delivery system for the treatment of tuberculosis. The carrier material to make the rifampicin (RIF)-loaded particles is a low molecular weight star-shaped polymer produced from glucosamine (molecular core building unit) and L-lactide (GluN-LLA). Stable particles with a very high 50% drug loading capacity were made via electrohydrodynamic atomization. Prolonged release (>14 days) of RIF from these particles is demonstrated. Drug release data fits the Korsmeyer-Peppas equation, which suggests the occurrence of a modified diffusion-controlled RIF release mechanism, and is also supported by differential scanning calorimetry and drug leaching tests. Cytotoxicity tests on Mycobacterium smegmatis showed that antibiotic-free GluN-LLA and polylactides (PLA) (reference material) particles did not show any significant anti-bacterial activity. The minimum inhibitory concentration and minimum bactericidal concentration values obtained for RIF-loaded particles showed 2- to 4-fold improvements in the anti-bacterial activity relative to the free drug. Cytotoxicity tests on macrophages indicated an increment in cell death as particle dose increased, but was not significantly affected by material type or particle size. Confocal microscopy was used to track internalization and localization of particles in the macrophages. GluN-LLA particles led to higher uptakes than the PLA particles. In addition, after phagocytosis, the GluN-LLA particles stayed in the cytoplasm and the particles showed a favorable long term drug release effect in killing intracellular bacteria compared to free RIF. The studies presented and discussed in this dissertation suggest that these drug carrier materials are potentially very attractive candidates for the development of high-payload, sustained-release antibiotic/resorbable polymer particle systems for treating bacterial lung infections.

Suspended-sediment concentrations, bedload, particle sizes, surrogate measurements, and annual sediment loads for selected sites in the lower Minnesota River Basin, water years 2011 through 2016

USGS Publications Warehouse

Groten, Joel T.; Ellison, Christopher A.; Hendrickson, Jon S.

2016-12-20

Accurate measurements of fluvial sediment are important for assessing stream ecological health, calculating flood levels, computing sediment budgets, and managing and protecting water resources. Sediment-enriched rivers in Minnesota are a concern among Federal, State, and local governments because turbidity and sediment-laden waters are the leading impairments and affect more than 6,000 miles of rivers in Minnesota. The suspended sediment in the lower Minnesota River is deleterious, contributing about 75 to 90 percent of the suspended sediment being deposited into Lake Pepin. The Saint Paul District of the U.S. Army Corps of Engineers and the Lower Minnesota River Watershed District collaborate to maintain a navigation channel on the lower 14.7 miles of the Minnesota River through scheduled dredging operations. The Minnesota Pollution Control Agency has adopted a sediment-reduction strategy to reduce sediment in the Minnesota River by 90 percent by 2040.The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, the Minnesota Pollution Control Agency, and the Lower Minnesota River Watershed District, collected suspended-sediment, bedload, and particle-size samples at five sites in the lower Minnesota River Basin during water years 2011 through 2014 and surrogate measurements of acoustic backscatter at one of these sites on the lower Minnesota River during water years 2012 through 2016 to quantify sediment loads and improve understanding of sediment-transport relations. Annual sediment loads were computed for calendar years 2011 through 2014.Data collected from water years 2011 through 2014 indicated that two tributaries, Le Sueur River and High Island Creek, had the highest sediment yield and concentrations of suspended sediment. These tributaries also had greater stream gradients than the sites on the Minnesota River. Suspended fines were greater than suspended sand at all sites in the study area. The range of median particle sizes matched the range for stream gradients from greatest to smallest. Bedload ranged from 3 to 20 percent of the total load at the Le Sueur River, Minnesota River at Mankato, and High Island Creek and was less than 1 percent of the total load at the Minnesota River near Jordan and at Fort Snelling State Park. The reach of the Minnesota River between Mankato and Jordan is a major source of sediment, with the sediment yield at Jordan being two and a half times greater than at Mankato. Between Jordan and Fort Snelling, the sediment yield decreases substantially, which indicates that the Minnesota River in this reach is a sink for sediment. Surrogate measurements (acoustic backscatter) collected with suspended-sediment concentration data from water years 2012 through 2016 from the Minnesota River at Fort Snelling State Park indicated strong relations between the acoustic backscatter and suspended-sediment concentrations. These results point to the dynamic nature of sediment aggradation, degradation, and transport in the Minnesota River Basin. The analyses described in this report will improve the understanding of sediment-transport relations and sediment budgets in the Minnesota River Basin.

Sediment deposition and trends and transport of phosphorus and other chemical constituents, Cheney Reservoir watershed, south-central Kansas

USGS Publications Warehouse

Mau, D.P.

2001-01-01

Sediment deposition, water-quality trends, and mass transport of phosphorus, nitrogen, selected trace elements, and selected pesticides within the Cheney Reservoir watershed in south-central Kansas were investigated using bathymetric survey data and reservoir bottom-sediment cores. Sediment loads in the reservoir were investigated by comparing 1964 topographic data to 1998 bathymetric survey data. Approximately 7,100 acre-feet of sediment deposition occurred in Cheney Reservoir from 1965 through 1998. As of 1998, sediment had filled 27 percent of the reservoir's inactive conservation storage pool, which is less than the design estimate of 34 percent. Mean annual sediment deposition was 209 acre-feet per year, or 0.22 acre-feet per year per square mile, and the mean annual sediment load was 453 million pounds per year. During the 3-year period from 1997 through 1999, 23 sediment cores were collected from the reservoir, and subsamples were analyzed for nutrients (phosphorus and nitrogen species), selected trace elements, and selected organic pesticides. Mean concentrations of total phosphorus in reservoir bottom sediment ranged from 94 milligrams per kilogram at the upstream end of the reservoir to 710 milligrams per kilogram farther downstream near the reservoir dam. The mean concentration for all sites was 480 milligrams per kilogram. Total phosphorus concentrations were greatest when more silt- and clay-sized particles were present. The implications are that if anoxic conditions (inadequate oxygen) occur near the dam, phosphorus could be released from the sediment and affect the drinking-water supply. Analysis of selected cores also indicates that total phosphorus concentrations in the reservoir sediment increased over time and were probably the result of nonpoint-source activities in the watershed, such as increased fertilizer use and livestock production. Mean annual phosphorus loading to Cheney Reservoir was estimated to be 226,000 pounds per year on the basis of calculations from deposited sediment in the reservoir. Mean total phosphorus concentration in the surface-water inflow to Cheney Reservoir was 0.76 milligram per liter, mean annual phosphorus yield of the watershed was estimated to be 0.38 pound per year per acre, and both are based on sediment deposition in the reservoir. A comparison of the Cheney Reservoir watershed to the Webster Reservoir, Tuttle Creek Lake, and Hillsdale Lake watersheds showed that phosphorus yields were smallest in the Webster Reservoir watershed where precipitation was less than in the other watersheds. Mean concentrations of total ammonia plus organic nitrogen in bottom sediment from Cheney Reservoir ranged from 1,200 to 2,400 milligrams per kilogram as nitrogen. A regression analysis between total ammonia plus organic nitrogen as nitrogen and sediment particle size showed a strong relation between the two variables and suggests, as with phosphorus, that total ammonia plus organic nitrogen as nitrogen adsorbs to the silt- and clay-sized particles that are transported to the deeper parts of the reservoir. An analysis of trends with depth of total ammonia plus organic nitrogen as nitrogen did not indicate a strong relation between the two variables despite the increase in fertilizer use in the watershed during the past 40 years. Selected cores were analyzed for trace elements. Concentrations of arsenic, chromium, copper, and nickel at many sites exceeded levels where adverse effects on aquatic organisms sometimes occur. Larger concentrations of these elements also occurred in sediment closer to the reservoir dam where there is a larger percentage of silt and clay in the bottom sediment than farther upstream. However, the lack of industrial or commercial land use in the watershed suggests that these concentrations may be the result of natural conditions. Organochlorine insecticides were detected in the reservoir-bottom sediment in Cheney Reservoir. DDT and its degradation products DDD and DD

Suspended particulate loads and transports in the nepheloid layer of the abyssal Atlantic Ocean

USGS Publications Warehouse

Biscaye, P.E.; Eittreim, S.L.

1977-01-01

Vertical profiles of light scattering from over 1000 L-DGO nephelometer stations in the Atlantic Ocean have been used to calculate mass concentrations of suspended particles based on a calibration from the western North American Basin. From these data are plotted the distributions of particulate concentrations at clear water and in the more turbid near-bottom water. Clear water is the broad minimum in concentration and light scattering that occurs at varying mid-depths in the water column. Concentrations at clear water are as much as one-to-two orders of magnitude lower than those in surface water but still reflect a similar geographic distribution: relatively higher concentrations at ocean margins, especially underneath upwelling areas, and the lowest concentrations underneath central gyre areas. These distributions within the clear water reflect surface-water biogenic productivity, lateral injection of particles from shelf areas and surface circulation patterns and require that the combination of downward vertical and horizontal transport processes of particles retain this pattern throughout the upper water column. Below clear water, the distribution of standing crops of suspended particulate concentrations in the lower water column are presented. The integration of mass of all particles per unit area (gross particulate standing crop) reflects a relative distribution similar to that at the surface and at clear water levels, superimposed on which is the strong imprint of boundary currents along the western margins of the Atlantic. Reducing the gross particulate standing crop by the integral of the concentration of clear water yields a net particulate standing crop. The distribution of this reflects primarily the interaction of circulating abyssal waters with the ocean bottom, i.e. a strong nepheloid layer which is coincident with western boundary currents and which diminishes in intensity equatorward. The resuspended particulate loads in the nepheloid layer of the basins west of the Mid-Atlantic Ridge, resulting from interaction of abyssal currents with the bottom, range from ??? 2 ?? 106 tons in the equatorial Guyana Basin to ??? 50 ?? 106 tons in the North American Basin. The total resuspended particulate load in the western basins (111 ?? 106 tons) is almost an order of magnitude greater than that in the basins east of the Mid-Atlantic Ridge (13 ?? 106 tons). The net northward flux of resuspended particles carried in the AABW drops from ??? 8 ?? 106 tons/year between the southern and northern ends of the Brazil Basin and remains ??? 1 ?? 106 tons/year across the Guyana Basin. ?? 1977.

Rotating belt sieves for primary treatment, chemically enhanced primary treatment and secondary solids separation.

PubMed

Rusten, B; Rathnaweera, S S; Rismyhr, E; Sahu, A K; Ntiako, J

2017-06-01

Fine mesh rotating belt sieves (RBS) offer a very compact solution for removal of particles from wastewater. This paper shows examples from pilot-scale testing of primary treatment, chemically enhanced primary treatment (CEPT) and secondary solids separation of biofilm solids from moving bed biofilm reactors (MBBRs). Primary treatment using a 350 microns belt showed more than 40% removal of total suspended solids (TSS) and 30% removal of chemical oxygen demand (COD) at sieve rates as high as 160 m³/m²-h. Maximum sieve rate tested was 288 m³/m²-h and maximum particle load was 80 kg TSS/m²-h. When the filter mat on the belt increased from 10 to 55 g TSS/m², the removal efficiency for TSS increased from about 35 to 60%. CEPT is a simple and effective way of increasing the removal efficiency of RBS. Adding about 1 mg/L of cationic polymer and about 2 min of flocculation time, the removal of TSS typically increased from 40-50% without polymer to 60-70% with polymer. Using coagulation and flocculation ahead of the RBS, separation of biofilm solids was successful. Removal efficiencies of 90% TSS, 83% total P and 84% total COD were achieved with a 90 microns belt at a sieve rate of 41 m³/m²-h.

Wear mechanisms in hybrid composites of Graphite-20 Pct SiC in A356 Aluminum Alloy (Al-7 Pct Si-0.3 Pct Mg)

NASA Astrophysics Data System (ADS)

Ames, W.; Alpas, A. T.

1995-01-01

The wear behavior of A356 aluminum alloy (Al-7 Pct Si-0.3 Pct Mg) matrix composites reinforced with 20 vol Pct SiC particles and 3 or 10 vol Pct graphite was investigated. These hybrid composites represent the merging of two philosophies in tribological material design: soft-particle lubrication by graphite and hard-particle reinforcement by carbide particles. The wear tests were performed using a block-on-ring (SAE 52100 steel) wear machine under dry sliding conditions within a load range of 1 to 441 N. The microstructural and compositional changes that took place during wear were characterized using scanning electron microscopy (SEM), Auger electron spectroscopy (AES), energy-dispersive X-ray spectroscopy (EDXA), and X-ray diffractometry (XRD). The wear resistance of 3 Pct graphite-20 Pct SiC-A356 hybrid composite was comparable to 20 Pct SiC-A356 without graphite at low and medium loads. At loads below 20 N, both hybrid and 20 Pct SiC-A356 composites without graphite demonstrated wear rates up to 10 times lower than the unreinforced A356 alloy due to the load-carrying capacity of SiC particles. The wear resistance of 3 Pct graphite 20 Pct SiC-A356 was 1 to 2 times higher than 10 Pct graphite-containing hybrid composites at high loads. However, graphite addition reduced the counterface wear. The unreinforced A356 and 20 Pct SiC-A356 showed a transition from mild to severe wear at 95 N and 225 N, respectively. Hybrid composites with 3 Pct and 10 Pct graphite did not show such a transition over the entire load range, indicating that graphite improved the seizure resistance of the composites. Tribolayers, mainly consisting of a compacted mixture of graphite, iron oxides, and aluminum, were generated on the surfaces of the hybrid composites. In the hybrid composites, the elimination of the severe wear (and hence the improvement in seizure resistance) was attributed to the reduction in friction-induced surface heating due to the presence of graphite- and iron-oxide-containing tribolayers.

Distribution of heavy metals and metalloids in bulk and particle size fractions of soils from coal-mine brownfield and implications on human health.

PubMed

Li, Hongxia; Ji, Hongbing; Shi, Chunjing; Gao, Yang; Zhang, Yan; Xu, Xiangyu; Ding, Huaijian; Tang, Lei; Xing, Yuxin

2017-04-01

Heavy metals (HMs) and metalloids migrate into their surroundings, thus increasing environmental risks and threatening human health. Current studies on coal-mine brownfields, however, have not thoroughly investigated soil-associated HMs and metalloids produced by coal mining. Therefore, this study explored the spatial and particle fraction distribution and human health implications of HMs and metalloids. The soil-associated HMs and metalloids are Arsenic (As), Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Manganese (Mn), Nickel (Ni), Lead (Pb), Scandium (Sc), Titanium (Ti) and Zinc (Zn). Results showed that Cd, Cu, Pb, and Ni were enriched in bulk soils. Cadmium, Cu and Pb from anthropogenic source were mainly found at entrance roadsides and in sites closest to coal mines. HMs and metalloids primarily accumulated in fine fractions (<1, 1-5, and 5-10 μm). Moreover, HM and metalloid loadings substantially accumulated in the 75-250 μm and 250-1000 μm fractions. Most fine soil fractions showed moderate to strong potential ecological risks, whereas all the coarse particle fractions (50-75, 75-250, and 250-1000 μm) presented slight potential ecological risk. Exposure to soil-associated HMs and metalloids mainly occurred via ingestion. The total non-carcinogenic risks to children and adults fell below the safe level of 1, whereas the total carcinogenic risks to these individuals were higher than that of the maximum acceptable level set by the United States Environmental Protection Agency (USEPA, 1 × 10 -4 ). The total carcinogenic risk was mainly contributed by Cd and Ni through ingestion and dermal access. Therefore, hygiene and food security in areas should be emphasized. Copyright © 2017 Elsevier Ltd. All rights reserved.

Concentration Measurements of Suspended Load using ADV with Influence of the Particle Size

NASA Astrophysics Data System (ADS)

Schwarzwälder, Kordula

2017-04-01

ADV backscatter data can be used under certain conditions to gain information about the concentrations of suspended loads. This was shown in many studies before (Fugate and Friedrichs 2002; Chanson et al 2008; Ha et al. 2009). This paper reports on a pre-study to investigate the influence of particle size on concentration measurements for suspended sediment load with ADV. The study was conducted in a flume in the Oskar-von-Miller-Institute using fresh water from a river including the natural suspended load. The ADV used in the experiments was a Vectrino Profiler (Nortek). In addition water samples were taken for TSS and TOC. For the measurements a surge was generated in the flume to ensure that also particles of larger size will be present in the water phase. The measurements and samples were taken during the whole surge event. Therefore we were able to find a good correlation between the backscatter data of the ADV and the TSS as well as TOC results. For the decreasing part of the flow event the concentration of TOC in the suspended load of the water phase is decreasing much slower than the TSS and results in a damped decrease of the backscatter values. This means that the results for concentration measurements might be slightly influenced by the size of the particles. Further evaluations of measurements conducted with a LISST SL (Sequoia) will be investigated to show the trend of the particle sizes during this process and fortify this result. David C. Fugate, Carl T. Friedrichs, Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST, Continental Shelf Research, Volume 22, Issues 11-13, 2002 H.K. Ha, W.-Y. Hsu, J.P.-Y. Maa, Y.Y. Shao, C.W. Holland, Using ADV backscatter strength for measuring suspended cohesive sediment concentration, Continental Shelf Research, Volume 29, Issue 10, 2009 Hubert Chanson, Maiko Takeuchi, Mark Trevethan, Using turbidity and acoustic backscatter intensity as surrogate measures of suspended sediment concentration in a small subtropical estuary, Journal of Environmental Management, Volume 88, Issue 4, 2008

Deep-sea fluxes of barium and lithogenic trace elements in the subtropical northeast Atlantic

NASA Astrophysics Data System (ADS)

Stern, Judith; Dellwig, Olaf; Waniek, Joanna J.

2017-04-01

Total particle flux, Barium and lithogenic trace element fluxes were measured at the mooring Kiel 276 (33°N, 22°W) in the deep-sea of the subtropical Northeast Atlantic. The particulate material was collected between 2002 and 2008 with a sediment trap in 2000 m depth and analyzed with ICP-OES/-MS to determine its geochemical composition. The particle flux is controlled by primary production, lithogenic particle inputs via atmospheric transport and the migration of the Azores Front. We used refractory trace elements (eg. Ti, Zr, and the rare earth elements) to demonstrate the changes in flux and composition of the material due to lithogenic inputs. Shortly after periods of high dust load and enhanced primary production an increase in lithogenic trace element fluxes occurred. Especially the formation of aggregates with biogenic matter seems to have a major impact on the downwards transport of lithogenic particles. The observation of particulate Ba is of great interest since it is known as a proxy for past and present primary production. Ba fluxes ranging between 0.02 mg m-2 d-1 and 1.21 mg m-2 d-1 with biogenic proportions up to 97%. The fluxes of particulate Barium in the water column are mainly attributed to the strength of primary production.

Radiopure Metal-Loaded Liquid Scintillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosero, Richard; Yeh, Minfang

2015-03-18

Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

Radiopure metal-loaded liquid scintillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosero, Richard; Yeh, Minfang, E-mail: yeh@bnl.gov

2015-08-17

Metal-loaded liquid scintillator plays a key role in particle and nuclear physics experiments. The applications of metal ions in various neutrino experiments and the purification methods for different scintillator components are discussed in this paper.

Influence of Particle Morphology on 3D Kinematic Behavior and Strain Localization of Sheared Sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alshibli, Khalid A.; Jarrar, Maha F.; Druckrey, Andrew M.

The constitutive behavior of sheared sand is highly influenced by particle morphology, gradation, mineralogy, specimen density, loading condition, stress path, and boundary conditions. The current literature lacks a three-dimensional (3D) systematic experimental study that investigates the influence of particle morphology, confining pressure, and specimen density on the failure mode of sheared sand. In this paper, surface texture, roundness, and sphericity of three uniform sands and glass beads with similar grain size were quantified by using 3D images of particles. In situ nondestructive 3D synchrotron microcomputed tomography (SMT) was used to monitor the deformation of medium-dense and very dense dry sandmore » specimens that were tested under axisymmetric triaxial loading condition at 15 and 400 kPa confining pressures. The particles were identified and tracked in 3D as shearing progressed within the specimens, and maps of incremental particle translation and rotation were developed and used to uncover the relationship between particle morphology, specimen density, and confining pressure on the deformation and failure mode of sheared sand. This paper discusses the relationship between the failure mode and particle morphology, specimen density, and confining pressure.« less

Particulate matter in pack ice of the Beaufort Gyre

USGS Publications Warehouse

Reimnitz, E.; Barnes, P.W.; Weber, W.S.

1993-01-01

Fine sediment occurred in very small patches of turbid ice, as thin spotty surface layers, in mud pellets or in old snowdrifts. The latter were widespread south of 74??N, containing an estimated 22 tonnes of silt and clay km-2. Average particle concentration in sea ice (40 mg1-1) was much higher than in sea water (0.8 mg 1 -1) or in new snow. Assuming one-third of the load is released each year, the estimated deposition rate would equal the measured Holocene rate (~2cm 1000 year-1). Therefore, modern sea-ice rafting represents a substantial fraction of the total Arctic Ocean sediment budget. -from Authors

Hydrocarbon pyrolysis reactor experimentation and modeling for the production of solar absorbing carbon nanoparticles

NASA Astrophysics Data System (ADS)

Frederickson, Lee Thomas

Much of combustion research focuses on reducing soot particulates in emissions. However, current research at San Diego State University (SDSU) Combustion and Solar Energy Laboratory (CSEL) is underway to develop a high temperature solar receiver which will utilize carbon nanoparticles as a solar absorption medium. To produce carbon nanoparticles for the small particle heat exchange receiver (SPHER), a lab-scale carbon particle generator (CPG) has been built and tested. The CPG is a heated ceramic tube reactor with a set point wall temperature of 1100-1300°C operating at 5-6 bar pressure. Natural gas and nitrogen are fed to the CPG where natural gas undergoes pyrolysis resulting in carbon particles. The gas-particle mixture is met downstream with dilution air and sent to the lab scale solar receiver. To predict soot yield and general trends in CPG performance, a model has been setup in Reaction Design CHEMKIN-PRO software. One of the primary goals of this research is to accurately measure particle properties. Mean particle diameter, size distribution, and index of refraction are calculated using Scanning Electron Microscopy (SEM) and a Diesel Particulate Scatterometer (DPS). Filter samples taken during experimentation are analyzed to obtain a particle size distribution with SEM images processed in ImageJ software. These results are compared with the DPS, which calculates the particle size distribution and the index of refraction from light scattering using Mie theory. For testing with the lab scale receiver, a particle diameter range of 200-500 nm is desired. Test conditions are varied to understand effects of operating parameters on particle size and the ability to obtain the size range. Analysis of particle loading is the other important metric for this research. Particle loading is measured downstream of the CPG outlet and dilution air mixing point. The air-particle mixture flows through an extinction tube where opacity of the mixture is measured with a 532 nm laser and detector. Beer's law is then used to calculate particle loading. The CPG needs to produce a certain particle loading for a corresponding receiver test. By obtaining the particle loading in the system, the reaction conversion to solid carbon in the CPG can be calculated to measure the efficiency of the CPG. To predict trends in reaction conversion and particle size from experimentation, the CHEMKIN-PRO computer model for the CPG is run for various flow rates and wall temperature profiles. These predictions were a reason for testing at higher wall set point temperatures. Based on these research goals, it was shown that the CPG consistently produces a mean particle diameter of 200-400 nm at the conditions tested, fitting perfectly inside the desired range. This led to successful lab scale SPHER testing which produced a 10-point efficiency increase and 150°C temperature difference with particles present. Also, at 3 g/s dilution air flow rate, an efficiency of 80% at an outlet temperature above 800°C was obtained. Promise was shown at higher CPG experimental temperatures to produce higher reaction conversion, both experimentally and in the model. However, based on wall temperature data taken during experimentation, it is apparent that the CPG needs to have multiple heating zones with separate temperature controllers in order to have an isothermal zone rather than a parabolic temperature profile. As for the computer model, it predicted much higher reaction conversion at higher temperature. The mass fraction of fuel in the inlet stream was shown to not affect conversion while increasing residence time led to increasing conversion. Particle size distribution in the model was far off and showed a bimodal distribution for one of the statistical methods. Using the results from experimentation and modeling, a preliminary CPG design is presented that will operate in a 5MWth receiver system.

Quantifying particulate matter deposition in Niwot Ridge, Colorado: Collection of dry deposition using marble inserts and particle imaging using the FlowCAM

NASA Astrophysics Data System (ADS)

Goss, Natasha R.; Mladenov, Natalie; Seibold, Christine M.; Chowanski, Kurt; Seitz, Leslie; Wellemeyer, T. Barret; Williams, Mark W.

2013-12-01

Atmospheric wet and dry deposition are important sources of carbon for remote alpine lakes and soils. The carbon inputs from dry deposition in alpine National Atmospheric Deposition Program (NADP) collectors, including aeolian dust and biological material, are not well constrained due to difficulties in retaining particulate matter in the collectors. Here, we developed and tested a marble insert for dry deposition collection at the Niwot Ridge Long Term Ecological Research Station (NWT LTER) Soddie site (3345 m) between 24 May and 8 November 2011. We conducted laboratory tests of the insert's effect on particulate matter (PM) mass and non-purgeable organic carbon (DOC) and found that the insert did not significantly change either measurement. Thus, the insert may enable dry deposition collection of PM and DOC at NADP sites. We then developed a method for enumerating the collected wet and dry deposition with the Flow Cytometer and Microscope (FlowCAM), a dynamic-image particle analysis tool. The FlowCAM has the potential to establish morphology, which affects particle settling and retention, through particle diameter and aspect ratio. Particle images were used to track the abundance of pollen grains over time. Qualitative image examination revealed that most particles were biological in nature, such as intact algal cells and pollen. Dry deposition loading to the Soddie site as determined by FlowCAM measurements was highly variable, ranging from 100 to >230 g ha-1 d-1 in June-August 2011 and peaking in late June. No significant difference in diameter or aspect ratio was found between wet and dry deposition, suggesting fundamental similarities between those deposition types. Although FlowCAM statistics and identification of particle types proved insightful, our total-particle enumeration method had a high variance and underestimated the total number of particles when compared to imaging of relatively large volumes (60-125 mL) from a single sample. We recommend use of the FlowCAM, especially for subclasses of particles, but in light of uncertainty in particle counts, believe that it should be paired with traditional methods such as microscopy in this stage of the technique's development. Analysis of well-mixed samples produced lower variability than settling methods used for algae samples. Use of the marble inserts in the dry deposition collector in the NADP context is recommended, and the implications of various particle counting and identification methods are explored.

Applying geochemical signatures of atmospheric dust to distinguish current mine emissions from legacy sources

NASA Astrophysics Data System (ADS)

Dong, Chenyin; Taylor, Mark Patrick

2017-07-01

Resolving the source of environmental contamination is the critical first step in remediation and exposure prevention. Australia's oldest silver-zinc-lead mine at Broken Hill (>130 years old) has generated a legacy of contamination and is associated with persistent elevated childhood blood lead (Pb) levels. However, the source of environmental Pb remains in dispute: current mine emissions; remobilized mine-legacy lead in soils and dusts; and natural lead from geological weathering of the gossan ore body. Multiple lines of evidence used to resolve this conundrum at Broken Hill include spatial and temporal variations in dust Pb concentrations and bioaccessibility, Pb isotopic compositions, particle morphology and mineralogy. Total dust Pb loading (mean 255 μg/m2/day) and its bioaccessibility (mean 75% of total Pb) is greatest adjacent to the active mining operations. Unweathered galena (PbS) found in contemporary dust deposits contrast markedly to Pb-bearing particles from mine-tailings and weathered gossan samples. Contemporary dust particles were more angular, had higher sulfur content and had little or no iron and manganese. Dust adjacent to the mine has Pb isotopic compositions (208Pb/207Pb: 2.3197; 206Pb/207Pb: 1.0406) that are a close match (99%) to the ore body with values slightly lower (94%) at the edge of the city. The weight of evidence supports the conclusion that contemporary dust Pb contamination in Broken Hill is sourced primarily from current mining activities and not from weathering or legacy sources.

The Effect of Calcium Phosphate Particle Shape and Size on their Antibacterial and Osteogenic Activity in the Delivery of Antibiotics in vitro

PubMed Central

Uskoković, Vuk; Batarni, Samir Shariff; Schweicher, Julien; King, Andrew; Desai, Tejal A.

2013-01-01

Powders composed of four morphologically different calcium phosphate particles were prepared by precipitation from aqueous solutions: flaky, brick-like, elongated orthogonal, and spherical. The particles were then loaded with either clindamycin phosphate as the antibiotic of choice, or fluorescein, a model molecule used to assess the drug release properties. A comparison was carried out of the comparative effect of such antibiotic-releasing materials on: sustained drug release profiles; Staphylococcus aureus growth inhibition; and osteogenic propensities in vitro. Raman spectroscopic analysis indicated the presence of various calcium phosphate phases, including monetite (flaky and elongated orthogonal particles), octacalcium phosphate (brick-shaped particles) and hydroxyapatite (spherical particles). Testing the antibiotic-loaded calcium phosphate powders for bacterial growth inhibition demonstrated satisfying antibacterial properties both in broths and on agar plates. All four calcium-phosphate-fluorescein powders exhibited sustained drug release over 21 days. The calcium phosphate sample with the highest specific surface area and the smallest, spherical particle size was the most effective in both drug loading and release, consequently having the highest antibacterial efficiency. Moreover, the highest cell viability, the largest gene expression upregulation of three different osteogenic markers – osteocalcin, osteopontin and Runx2 - as well as the least disrupted cell cytoskeleton and cell morphologies were also noticed for the calcium phosphate powder composed of smallest, spherical nanosized particles. Still, all four powders exerted a viable effect on osteoblastic MC3T3-E1 cells in vitro, as evidenced by both morphological assessments on fluorescently stained cells and measurements of their mitochondrial activity. The obtained results suggest that the nanoscale particle size and the corresponding coarseness of the surface of particle conglomerates as the cell attachment points may present a favorable starting point for the development of calcium-phosphate-based osteogenic drug delivery devices. PMID:23484624

Estimation of constituent concentrations, densities, loads, and yields in lower Kansas River, northeast Kansas, using regression models and continuous water-quality monitoring, January 2000 through December 2003

USGS Publications Warehouse

Rasmussen, Teresa J.; Ziegler, Andrew C.; Rasmussen, Patrick P.

2005-01-01

The lower Kansas River is an important source of drinking water for hundreds of thousands of people in northeast Kansas. Constituents of concern identified by the Kansas Department of Health and Environment (KDHE) for streams in the lower Kansas River Basin include sulfate, chloride, nutrients, atrazine, bacteria, and sediment. Real-time continuous water-quality monitors were operated at three locations along the lower Kansas River from July 1999 through September 2004 to provide in-stream measurements of specific conductance, pH, water temperature, turbidity, and dissolved oxygen and to estimate concentrations for constituents of concern. Estimates of concentration and densities were combined with streamflow to calculate constituent loads and yields from January 2000 through December 2003. The Wamego monitoring site is located 44 river miles upstream from the Topeka monitoring site, which is 65 river miles upstream from the DeSoto monitoring site, which is 18 river miles upstream from where the Kansas River flows into the Missouri River. Land use in the Kansas River Basin is dominated by grassland and cropland, and streamflow is affected substantially by reservoirs. Water quality at the three monitoring sites varied with hydrologic conditions, season, and proximity to constituent sources. Nutrient and sediment concentrations and bacteria densities were substantially larger during periods of increased streamflow, indicating important contributions from nonpoint sources in the drainage basin. During the study period, pH remained well above the KDHE lower criterion of 6.5 standard units at all sites in all years, but exceeded the upper criterion of 8.5 standard units annually between 2 percent of the time (Wamego in 2001) and 65 percent of the time (DeSoto in 2003). The dissolved oxygen concentration was less than the minimum aquatic-life-support criterion of 5.0 milligrams per liter less than 1 percent of the time at all sites. Dissolved solids, a measure of the dissolved material in water, exceeded 500 milligrams per liter about one-half of the time at the three Kansas River sites. Larger dissolved-solids concentrations upstream likely were a result of water inflow from the highly mineralized Smoky Hill River that is diluted by tributary flow as it moves downstream. Concentrations of total nitrogen and total phosphorus at the three monitoring sites exceeded the ecoregion water-quality criteria suggested by the U.S. Environmental Protection Agency during the entire study period. Median nitrogen and phosphorus concentrations were similar at all three sites, and nutrient load increased moving from the upstream to downstream sites. Total nitrogen and total phosphorus yields were nearly the same from site to site indicating that nutrient sources were evenly distributed throughout the lower Kansas River Basin. About 11 percent of the total nitrogen load and 12 percent of the total phosphorus load at DeSoto during 2000-03 originated from wastewater-treatment facilities. Escherichia coli bacteria densities were largest at the middle site, Topeka. On average, 83 percent of the annual bacteria load at DeSoto during 2000-03 occurred during 10 percent of the time, primarily in conjunction with runoff. The average annual sediment loads at the middle and downstream monitoring sites (Topeka and DeSoto) were nearly double those at the upstream site (Wamego). The average annual sediment yield was largest at Topeka. On average, 64 percent of the annual suspended-sediment load at DeSoto during 2000-03 occurred during 10 percent of the time. Trapping of sediment by reservoirs located on contributing tributaries decreases transport of sediment and sediment-related constituents. The average annual suspended-sediment load in the Kansas River at DeSoto during 2000-03 was estimated at 1.66 million tons. An estimated 13 percent of this load consisted of sand-size particles, so approximately 216,000 tons of sand were transported

Utilizing the protein corona around silica nanoparticles for dual drug loading and release

NASA Astrophysics Data System (ADS)

Shahabi, Shakiba; Treccani, Laura; Dringen, Ralf; Rezwan, Kurosch

2015-10-01

A protein corona forms spontaneously around silica nanoparticles (SNPs) in serum-containing media. To test whether this protein corona can be utilized for the loading and release of anticancer drugs we incorporated the hydrophilic doxorubicin, the hydrophobic meloxicam as well as their combination in the corona around SNPs. The application of corona-covered SNPs to osteosarcoma cells revealed that drug-free particles did not affect the cell viability. In contrast, SNPs carrying a protein corona with doxorubicin or meloxicam lowered the cell proliferation in a concentration-dependent manner. In addition, these particles had an even greater antiproliferative potential than the respective concentrations of free drugs. The best antiproliferative effects were observed for SNPs containing both doxorubicin and meloxicam in their corona. Co-localization studies revealed the presence of doxorubicin fluorescence in the nucleus and lysosomes of cells exposed to doxorubicin-containing coated SNPs, suggesting that endocytotic uptake of the SNPs facilitates the cellular accumulation of the drug. Our data demonstrate that the protein corona, which spontaneously forms around nanoparticles, can be efficiently exploited for loading the particles with multiple drugs for therapeutic purposes. As drugs are efficiently released from such particles they may have a great potential for nanomedical applications.A protein corona forms spontaneously around silica nanoparticles (SNPs) in serum-containing media. To test whether this protein corona can be utilized for the loading and release of anticancer drugs we incorporated the hydrophilic doxorubicin, the hydrophobic meloxicam as well as their combination in the corona around SNPs. The application of corona-covered SNPs to osteosarcoma cells revealed that drug-free particles did not affect the cell viability. In contrast, SNPs carrying a protein corona with doxorubicin or meloxicam lowered the cell proliferation in a concentration-dependent manner. In addition, these particles had an even greater antiproliferative potential than the respective concentrations of free drugs. The best antiproliferative effects were observed for SNPs containing both doxorubicin and meloxicam in their corona. Co-localization studies revealed the presence of doxorubicin fluorescence in the nucleus and lysosomes of cells exposed to doxorubicin-containing coated SNPs, suggesting that endocytotic uptake of the SNPs facilitates the cellular accumulation of the drug. Our data demonstrate that the protein corona, which spontaneously forms around nanoparticles, can be efficiently exploited for loading the particles with multiple drugs for therapeutic purposes. As drugs are efficiently released from such particles they may have a great potential for nanomedical applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04726a

Evaluating the dynamical characteristics of particle matter emissions in an open ore yard with industrial operation activities.

PubMed

Cong, X C; Yang, G S; Qu, J H; Dai, M X

2016-11-01

A study to investigate the dynamical characteristics of particle matter emissions in a working open yard is conducted in Caofeidian Port of Hebei Province, China. The average diurnal concentrations of the total suspended particulate (TSP) matter and respirable particulate matter (PM 10 and PM 5 ) are monitored during the field measurement campaign. Sampling is performed at a regular interval at 8 monitoring stations in the yard with normal industrial activities. The average TSP, PM 10 and PM 5 concentrations range from 285 to 568, 198 to 423 and 189 to 330 μg.m-3 in the yard, respectively. The linear regression correlation coefficient of TSP/PM 10 and TSP/PM 5 is 0.95±0.01 and 0.88±0.02, respectively.By using the Spearman correlation method, the wind speed and relative humidity are both weakly correlated with the PM 10 and PM 5 concentrations according to the measurements. In addition, industrial operation activities, such as vehicular traffic in the yard and the loading time of stackers, are significantly positively correlated with the PM concentration. Using the multivariate regression method, the main parameters influencing the TSP concentration variations are integratedly analysed. The traffic volume is found to be a significant predictor of TSP concentration variation, with the smallest P value (P<0.05).To understand the dynamical characteristics of particle emissions in the yard, the emissions from the truck transports, that is, from unpaved haul roads and from the loading process, are established. Then, the dynamical emission factor (EF D ) based on the industrial activities in the yard is proposed. The dynamical emissions average 5.25x10 5 kg.year -1 and EF D is evaluated to be 0.29 kg.(ton.day) -1 during the measurement period. These outcomes have meaningful implications not only for understanding the dynamical characteristics of particle emissions in the working stockyard but also for implementing effective control measures at appropriate sites in the harbour area.

Design of a photoswitchable hollow microcapsular drug delivery system by using a supramolecular drug-loading approach.

PubMed

Xiao, Wang; Chen, Wei-Hai; Zhang, Jing; Li, Cao; Zhuo, Ren-Xi; Zhang, Xian-Zheng

2011-11-24

In this study, photoswitchable microcapsules were fabricated based on host-guest interactions between α-cyclodextrin (α-CD) and azobenzene (Azo). Carboxymethyl dextran-graft-α-CD (CMD-g-α-CD) and poly(acrylic acid) N-aminododecane p-azobenzeneaminosuccinic acid (PAA-C(12)-Azo) were assembled layer by layer on CaCO(3) particles. α-CD-rhodamine B (α-CD-RhB), used as a model drug, was loaded on PAA-C(12)-Azo layers by host-guest interaction. After removal of CaCO(3) particles by ethylenediaminetetraacetic acid (EDTA), hollow microcapsules loaded with α-CD-RhB were obtained. Since the interactions between α-CD and Azo were photosensitive, the capsules could be dissociated with the irradiation of UV light, followed by the release of the model drug, α-CD-RhB. Compared with traditional drug-loading approaches such as chemical bonding and physical adsorption, our supramolecular drug-loading system has a facile loading process, ideal bonding strength, and photoswitchable behavior. These photosensitive microcapsules exhibit great potential in biomedical applications. © 2011 American Chemical Society

Loading relativistic Maxwell distributions in particle simulations

NASA Astrophysics Data System (ADS)

Zenitani, S.

2015-12-01

In order to study energetic plasma phenomena by using particle-in-cell (PIC) and Monte-Carlo simulations, we need to deal with relativistic velocity distributions in these simulations. However, numerical algorithms to deal with relativistic distributions are not well known. In this contribution, we overview basic algorithms to load relativistic Maxwell distributions in PIC and Monte-Carlo simulations. For stationary relativistic Maxwellian, the inverse transform method and the Sobol algorithm are reviewed. To boost particles to obtain relativistic shifted-Maxwellian, two rejection methods are newly proposed in a physically transparent manner. Their acceptance efficiencies are 􏰅50% for generic cases and 100% for symmetric distributions. They can be combined with arbitrary base algorithms.

Numerical simulation of large-scale bed load particle tracer advection-dispersion in rivers with free bars

USGS Publications Warehouse

Iwasaki, Toshiki; Nelson, Jonathan M.; Shimizu, Yasuyuki; Parker, Gary

2017-01-01

Asymptotic characteristics of the transport of bed load tracer particles in rivers have been described by advection-dispersion equations. Here we perform numerical simulations designed to study the role of free bars, and more specifically single-row alternate bars, on streamwise tracer particle dispersion. In treating the conservation of tracer particle mass, we use two alternative formulations for the Exner equation of sediment mass conservation: the flux-based formulation, in which bed elevation varies with the divergence of the bed load transport rate, and the entrainment-based formulation, in which bed elevation changes with the net deposition rate. Under the condition of no net bed aggradation/degradation, a 1-D flux-based deterministic model that does not describe free bars yields no streamwise dispersion. The entrainment-based 1-D formulation, on the other hand, models stochasticity via the probability density function (PDF) of particle step length, and as a result does show tracer dispersion. When the formulation is generalized to 2-D to include free alternate bars, however, both models yield almost identical asymptotic advection-dispersion characteristics, in which streamwise dispersion is dominated by randomness inherent in free bar morphodynamics. This randomness can result in a heavy-tailed PDF of waiting time. In addition, migrating bars may constrain the travel distance through temporary burial, causing a thin-tailed PDF of travel distance. The superdiffusive character of streamwise particle dispersion predicted by the model is attributable to the interaction of these two effects.

Numerical simulation of large-scale bed load particle tracer advection-dispersion in rivers with free bars

NASA Astrophysics Data System (ADS)

Iwasaki, Toshiki; Nelson, Jonathan; Shimizu, Yasuyuki; Parker, Gary

2017-04-01

Asymptotic characteristics of the transport of bed load tracer particles in rivers have been described by advection-dispersion equations. Here we perform numerical simulations designed to study the role of free bars, and more specifically single-row alternate bars, on streamwise tracer particle dispersion. In treating the conservation of tracer particle mass, we use two alternative formulations for the Exner equation of sediment mass conservation: the flux-based formulation, in which bed elevation varies with the divergence of the bed load transport rate, and the entrainment-based formulation, in which bed elevation changes with the net deposition rate. Under the condition of no net bed aggradation/degradation, a 1-D flux-based deterministic model that does not describe free bars yields no streamwise dispersion. The entrainment-based 1-D formulation, on the other hand, models stochasticity via the probability density function (PDF) of particle step length, and as a result does show tracer dispersion. When the formulation is generalized to 2-D to include free alternate bars, however, both models yield almost identical asymptotic advection-dispersion characteristics, in which streamwise dispersion is dominated by randomness inherent in free bar morphodynamics. This randomness can result in a heavy-tailed PDF of waiting time. In addition, migrating bars may constrain the travel distance through temporary burial, causing a thin-tailed PDF of travel distance. The superdiffusive character of streamwise particle dispersion predicted by the model is attributable to the interaction of these two effects.

Anaerobic co-digestion of food waste and dairy manure: effects of food waste particle size and organic loading rate.

PubMed

Agyeman, Fred O; Tao, Wendong

2014-01-15

This study was to comprehensively evaluate the effects of food waste particle size on co-digestion of food waste and dairy manure at organic loading rates increased stepwise from 0.67 to 3 g/L/d of volatile solids (VS). Three anaerobic digesters were fed semi-continuously with equal VS amounts of food waste and dairy manure. Food waste was ground to 2.5 mm (fine), 4 mm (medium), and 8 mm (coarse) for the three digesters, respectively. Methane production rate and specific methane yield were significantly higher in the digester with fine food waste. Digestate dewaterability was improved significantly by reducing food waste particle size. Specific methane yield was highest at the organic loading rate of 2g VS/L/d, being 0.63, 0.56, and 0.47 L CH4/g VS with fine, medium, and coarse food waste, respectively. Methane production rate was highest (1.40-1.53 L CH4/L/d) at the organic loading rate of 3 g VS/L/d. The energy used to grind food waste was minor compared with the heating value of the methane produced. Copyright © 2013 Elsevier Ltd. All rights reserved.

Experimental investigation on regulated and unregulated emissions of a diesel engine fueled with ultra-low sulfur diesel fuel blended with biodiesel from waste cooking oil.

PubMed

Di, Yage; Cheung, C S; Huang, Zuohua

2009-01-01

Experiments were conducted on a 4-cylinder direct-injection diesel engine using ultra-low sulfur diesel, bi oesel and their blends, to investigate the regulated and unregulated emissions of the engine under five engine loads at an engine speed of 1800 rev/min. Blended fuels containing 19.6%, 39.4%, 59.4% and 79.6% by volume of biodiesel, corresponding to 2%, 4%, 6% and 8% by mass of oxygen in the blended fuel, were used. Biodiesel used in this study was converted from waste cooking oil. The following results are obtained with an increase of biodiesel in the fuel. The brake specific fuel consumption and the brake thermal efficiency increase. The HC and CO emissions decrease while NO(x) and NO(2) emissions increase. The smoke opacity and particulate mass concentrations reduce significantly at high engine load. In addition, for submicron particles, the geometry mean diameter of the particles becomes smaller while the total number concentration increases. For the unregulated gaseous emissions, generally, the emissions of formaldehyde, 1,3-butadiene, toluene, xylene decrease, however, acetaldehyde and benzene emissions increase. The results indicate that the combination of ultra-low sulfur diesel and biodiesel from waste cooking oil gives similar results to those in the literature using higher sulfur diesel fuels and biodiesel from other sources.

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

A test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPs) was conducted . Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical characterization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions. Field testing was conducted in twomore » phases. The Phase I field program was performed over the period of August 24 through September 20, 1992, at the Tennessee Valley Authority Widows Creek Unit 8 Power Station, located near Stevenson (Jackson County), Alabama, on the Tennessee River. Sampling activities for Phase II were conducted from September 11 through October 14, 1993. Widows Creek Unit 8 is a 575-megawatt plant that uses bituminous coal averaging 3.7% sulfur and 13% ash. Downstream of the boiler, a venture wet scrubbing system is used for control of both sulfur dioxide and particulate emissions. There is no electrostatic precipitator (ESP) in this system. This system is atypical and represents only about 5% of the US utility industry. However, this site was chosen for this study because of the lack of information available for this particulate emission control system.« less

Investigation of Anaerobic Fluidized Bed Reactor/ Aerobic Moving Bed Bio Reactor (AFBR/MMBR) System for Treatment of Currant Wastewater

PubMed Central

JAFARI, Jalil; MESDAGHINIA, Alireza; NABIZADEH, Ramin; FARROKHI, Mehrdad; MAHVI, Amir Hossein

2013-01-01

Background: Anaerobic treatment methods are more suitable for the treatment of concentrated wastewater streams, offer lower operating costs, the production of usable biogas product. The aim of this study was to investigate the performance of an Anaerobic Fluidized Bed Reactor (AFBR)-Aerobic Moving Bed Bio Reactor (MBBR) in series arrangement to treat Currant wastewater. Methods: The bed materials of AFBR were cylindrical particles made of PVC with a diameter of 2–2.3 mm, particle density of 1250 kg/m3. The volume of all bed materials was 1.7 liter which expanded to 2.46 liters in fluidized situation. In MBBR, support media was composed of 1.5 liters Bee-Cell 2000 having porosity of 87% and specific surface area of 650m2/m3. Results: When system operated at 35 ºC, chemical oxygen demand (COD) removal efficiencies were achieved to 98% and 81.6% for organic loading rates (OLR) of 9.4 and 24.2 g COD/l.d, and hydraulic retention times (HRT) of 48 and 18 h, in average COD concentration feeding of 18.4 g/l, respectively. Conclusion: The contribution of AFBR in total COD removal efficiency at an organic loading rate (OLR) of 9.4 g COD/l.d was 95%, and gradually decreased to 76.5% in OLR of 24.2 g COD/l.d. Also with increasing in organic loading rate the contribution of aerobic reactor in removing COD gradually decreased. In this system, the anaerobic reactor played the most important role in the removal of COD, and the aerobic MBBR was actually needed to polish the anaerobic treated wastewater. PMID:26056640

Current and efficiency optimization under oscillating forces in entropic barriers

NASA Astrophysics Data System (ADS)

Nutku, Ferhat; Aydıner, Ekrem

2016-09-01

The transport of externally overdriven particles confined in entropic barriers is investigated under various types of oscillating and temporal forces. Temperature, load, and amplitude dependence of the particle current and energy conversion efficiency are investigated in three dimensions. For oscillating forces, the optimized temperature-load, amplitude-temperature, and amplitude-load intervals are determined when fixing the amplitude, load, and temperature, respectively. By using three-dimensional plots rather than two-dimensional ones, it is clearly shown that oscillating forces provide more efficiency compared with a temporal one in specified optimized parameter regions. Furthermore, the dependency of efficiency to the angle between the unbiased driving force and a constant force is investigated and an asymmetric angular dependence is found for all types of forces. Finally, it is shown that oscillating forces with a high amplitude and under a moderate load lead to higher efficiencies than a temporal force at both low and high temperatures for the entire range of contact angle. Project supported by the Istanbul University, Turkey (Grant No. 55383).

Size, Loading Efficiency, and Cytotoxicity of Albumin-Loaded Chitosan Nanoparticles: An Artificial Neural Networks Study.

PubMed

Baharifar, Hadi; Amani, Amir

2017-01-01

When designing nanoparticles for drug delivery, many variables such as size, loading efficiency, and cytotoxicity should be considered. Usually, smaller particles are preferred in drug delivery because of longer blood circulation time and their ability to escape from immune system, whereas smaller nanoparticles often show increased toxicity. Determination of parameters which affect size of particles and factors such as loading efficiency and cytotoxicity could be very helpful in designing drug delivery systems. In this work, albumin (as a protein drug model)-loaded chitosan nanoparticles were prepared by polyelectrolyte complexation method. Simultaneously, effects of 4 independent variables including chitosan and albumin concentrations, pH, and reaction time were determined on 3 dependent variables (i.e., size, loading efficiency, and cytotoxicity) by artificial neural networks. Results showed that concentrations of initial materials are the most important factors which may affect the dependent variables. A drop in the concentrations decreases the size directly, but they simultaneously decrease loading efficiency and increase cytotoxicity. Therefore, an optimization of the independent variables is required to obtain the most useful preparation. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Sources and loads of nutrients in the South Platte River, Colorado and Nebraska, 1994-95

USGS Publications Warehouse

Litke, D.W.

1996-01-01

The South Platte River Basin was one of 20 river basins selected in 1991 for investigation as part of the U.S. Geological Survey's National Water- Quality Assessment (NAWQA) Program. Nationwide, nutrients have been identified as one of the primary nationwide water-quality concerns and are of particular interest in the South Platte River Basin where nutrient concentrations are large compared to concentrations in other NAWQA river basins. This report presents estimates of the magnitude of nutrient-source inputs to the South Platte River Basin, describes nutrient concen- trations and loads in the South Platte River during different seasons, and presents comparisons of nutrient inputs to instream nutrient loads. Annual nutrient inputs to the basin were estimated to be 306,000 tons of nitrogen and 41,000 tons of phosphorus. The principal nutrient sources were wastewater-treatment plants, fertilizer and manure applications, and atmospheric deposition. To characterize nutrient concentrations and loads in the South Platte River during different seasons, five nutrient synoptic samplings were conducted during 1994 and 1995. Upstream from Denver, Colorado, during April 1994 and January 1995, total nitrogen concentrations were less than 2 milligrams per liter (mg/L), and total phosphorus concentrations were less than 0.2 mg/L. The water in the river at this point was derived mostly from forested land in the mountains west of Denver. Total nutrient concentrations increased through the Denver metropolitan area, and concentration peaks occurred just downstream from each of Denver's largest wastewater-treatment plants with maximum concentrations of 13.6 mg/L total nitrogen and 2.4 mg/L total phosphorus. Nutrient concen- concentrations generally decreased downstream from Denver. Upstream from Denver during April 1994 and January 1995, total nitrogen loads were less than 1,000 pounds per day (lb/d), and total phosphorus loads were less than 125 lb/d. Total nutrient loads increased through the Denver metropolitan area, and load peaks occurred just downstream from each of Denver's largest wastewater-treatment plants, with a maximum load of 14,000 lb/d total nitrogen and 2,300 lb/d total phosphorus. In April 1994, nutrient loads generally decreased from Henderson, Colorado, to North Platte, Nebraska. In January 1995, however, nutrient loads increased from Henderson to Kersey, Colorado (maximum loads of 31,000 lb/d total nitrogen and 3,000 lb/d total phosphorus), and then decreased from Kersey to North Platte. Seasonal nutrient loads primarily were dependent on streamflow. Total nitrogen loads were largest in June 1994 and January 1995 when streamflows also were largest. During June, streamflow was large, but nitrogen concentrations were small, which indicated that snowmelt runoff diluted the available supply of nitrogen. Total phosphorus loads were largest in June, when streamflow and phosphorus concentrations were large, which indicated an additional source of phosphorus during snowmelt runoff. Streamflow along the South Platte River was smallest in April and August 1994, and nutrient loads also were smallest during these months. The downstream pattern for nutrient loads did not vary much by season. Loads were large at Henderson, decreased between Henderson and Kersey, and usually were largest at Kersey. The magnitude of the decrease in loads between Henderson and Kersey varied between synoptics and was dependent on the amount of water removed by irrigation ditches. Nutrient loads leaving the basin were very small compared to the estimated total nutrient inputs to the basin. Streamflow balances indicated that the South Platte River is a gaining river throughout much of its length; streamflow-balance residuals were as large as 15 cubic feet per second per mile. Nutrient-load balances indicated that increases in river nitrate loads were, in some places, due to nitrification and, elsewhere, were due to the influx of nitrate-enriched ground water to

Measuring the Bed Load velocity in Laboratory flumes using ADCP and Digital Cameras

NASA Astrophysics Data System (ADS)

Conevski, Slaven; Guerrero, Massimo; Rennie, Colin; Bombardier, Josselin

2017-04-01

Measuring the transport rate and apparent velocity of the bedload is notoriously hard and there is not a certain technique that would obtain continues data. There are many empirical models, based on the estimation of the shear stress, but only few involve direct measurement of the bed load velocity. The bottom tracking (BT) mode of an acoustic Doppler current profiler (ADCP) has been used many times to estimate the apparent velocity of the bed load. Herein is the basic idea, to exploit the bias of the BT signal towards the bed load movement and to calibrate this signal with traditional measuring techniques. These measurements are quite scarce and seldom reliable since there are not taken in controlled conditions. So far, no clear confirmation has been conducted in laboratory-controlled conditions that would attest the assumptions made in the estimation of the apparent bed load velocity, nor in the calibration of the empirical equations. Therefore, this study explores several experiments under stationary conditions, where the signal of the ADCP BT mode is recorded and compared to the bed load motion recorded by digital camera videography. The experiments have been performed in the hydraulic laboratories of Ottawa and Bologna, using two different ADCPs and two different high resolution cameras. In total, more then 30 experiments were performed for different sediment mixtures and different hydraulic conditions. In general, a good match is documented between the apparent bed load velocity measured by the ADCP and the videography. The slight deviation in single experiments can be explained by gravel particles inhomogeneity, difficult in reproducing the same hydro-sedimentological conditions and the randomness of the backscattering strength.

The Effect of Detonation Wave Incidence Angle on the Acceleration of Flyers by Explosives Heavily Laden with Inert Additives

NASA Astrophysics Data System (ADS)

Loiseau, Jason; Georges, William; Frost, David; Higgins, Andrew

2015-06-01

The incidence angle of a detonation wave is often assumed to weakly influence the terminal velocity of an explosively driven flyer. For explosives heavily loaded with dense additives, this may not be true due to differences in momentum and energy transfer between detonation products, additive particles, and the flyer. For tangential incidence the particles are first accelerated against the flyer via an expansion fan, whereas they are first accelerated by the detonation wave in the normal case. In the current study we evaluate the effect of normal versus tangential incidence on the acceleration of flyers by nitromethane heavily loaded with a variety of additives. Normal detonation was initiated via an explosively driven slapper. Flyer acceleration was measured with heterodyne laser interferometry (PDV). The influence of wave angle is evaluated by comparing the terminal velocity in the two cases (i.e., normal and grazing) for the heavily loaded mixtures. The decrement in flyer velocity correlated primarily with additive volume fraction and had a weak dependence on additive density or particle size. The Gurney energy of the heterogeneous explosive was observed to increase with flyer mass, presumably due to the timescale over which impinging particles could transfer momentum.

Distribution and identification of culturable airborne microorganisms in a Swiss milk processing facility.

PubMed

Brandl, Helmut; Fricker-Feer, Claudia; Ziegler, Dominik; Mandal, Jyotshna; Stephan, Roger; Lehner, Angelika

2014-01-01

Airborne communities (mainly bacteria) were sampled and characterized (concentration levels and diversity) at 1 outdoor and 6 indoor sites within a Swiss dairy production facility. Air samples were collected on 2 sampling dates in different seasons, one in February and one in July 2012 using impaction bioaerosol samplers. After cultivation, isolates were identified by mass spectrometry (matrix-assisted laser desorption/ionization-time-of-flight) and molecular (sequencing of 16S rRNA and rpoB genes) methods. In general, total airborne particle loads and total bacterial counts were higher in winter than in summer, but remained constant within each indoor sampling site at both sampling times (February and July). Bacterial numbers were generally very low (<100 cfu/m(3) of air) during the different steps of milk powder production. Elevated bacterial concentrations (with mean values of 391 ± 142 and 179 ± 33 cfu/m(3) of air during winter and summer sampling, respectively; n=15) occurred mainly in the "logistics area," where products in closed tins are packed in secondary packaging material and prepared for shipping. However, total bacterial counts at the outdoor site varied, with a 5- to 6-fold higher concentration observed in winter compared with summer. Twenty-five gram-positive and gram-negative genera were identified as part of the airborne microflora, with Bacillus and Staphylococcus being the most frequent genera identified. Overall, the culturable microflora community showed a composition typical and representative for the specific location. Bacterial counts were highly correlated with total airborne particles in the size range 1 to 5 µm, indicating that a simple surveillance system based upon counting of airborne particles could be implemented. The data generated in this study could be used to evaluate the effectiveness of the dairy plant's sanitation program and to identify potential sources of airborne contamination, resulting in increased food safety. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Direct and indirect atmospheric deposition of PCBs to the Delaware River watershed.

PubMed

Totten, Lisa A; Panangadan, Maya; Eisenreich, Steven J; Cavallo, Gregory J; Fikslin, Thomas J

2006-04-01

Atmospheric deposition can be an important source of PCBs to aquatic ecosystems. To develop the total maximum daily load (TMDL) for polychlorinated biphenyls (PCBs) for the tidal Delaware River (water-quality Zones 2-5), estimates of the loading of PCBs to the river from atmospheric deposition were generated from seven air-monitoring sites along the river. This paper presents the atmospheric PCB data from these sites, estimates direct atmospheric deposition fluxes, and assesses the importance of atmospheric deposition relative to other sources of PCBs to the river. Also, the relationship between indirect atmospheric deposition and PCB loads from minor tributaries to the Delaware River is discussed. Data from these sites revealed high atmospheric PCB concentrations in the Philadelphia/Camden urban area and lower regional background concentrations in the more remote areas. Wet, dry particle, and gaseous absorption deposition are estimated to contribute about 0.6, 1.8, and 6.5 kg year-(-1) sigmaPCBs to the River, respectively, exceeding the TMDL of 0.139 kg year(-1) by more than an order of magnitude. Penta-PCB watershed fluxes were obtained by dividing the tributary loads by the watershed area. The lowest of these watershed fluxes are less than approximately 1 ng m(-2) day(-1) for penta-PCB and probably indicates pristine watersheds in which PCB loads are dominated by atmospheric deposition. In these watersheds, the pass-through efficiency of PCBs is estimated to be on the order of 1%.

Peptide/protein vaccine delivery system based on PLGA particles.

PubMed

Allahyari, Mojgan; Mohit, Elham

2016-03-03

Due to the excellent safety profile of poly (D,L-lactide-co-glycolide) (PLGA) particles in human, and their biodegradability, many studies have focused on the application of PLGA particles as a controlled-release vaccine delivery system. Antigenic proteins/peptides can be encapsulated into or adsorbed to the surface of PLGA particles. The gradual release of loaded antigens from PLGA particles is necessary for the induction of efficient immunity. Various factors can influence protein release rates from PLGA particles, which can be defined intrinsic features of the polymer, particle characteristics as well as protein and environmental related factors. The use of PLGA particles encapsulating antigens of different diseases such as hepatitis B, tuberculosis, chlamydia, malaria, leishmania, toxoplasma and allergy antigens will be described herein. The co-delivery of antigens and immunostimulants (IS) with PLGA particles can prevent the systemic adverse effects of immunopotentiators and activate both dendritic cells (DCs) and natural killer (NKs) cells, consequently enhancing the therapeutic efficacy of antigen-loaded PLGA particles. We will review co-delivery of different TLR ligands with antigens in various models, highlighting the specific strengths and weaknesses of the system. Strategies to enhance the immunotherapeutic effect of DC-based vaccine using PLGA particles can be designed to target DCs by functionalized PLGA particle encapsulating siRNAs of suppressive gene, and disease specific antigens. Finally, specific examples of cellular targeting where decorating the surface of PLGA particles target orally administrated vaccine to M-cells will be highlighted.

Peptide/protein vaccine delivery system based on PLGA particles

PubMed Central

Allahyari, Mojgan; Mohit, Elham

2016-01-01

abstract Due to the excellent safety profile of poly (D,L-lactide-co-glycolide) (PLGA) particles in human, and their biodegradability, many studies have focused on the application of PLGA particles as a controlled-release vaccine delivery system. Antigenic proteins/peptides can be encapsulated into or adsorbed to the surface of PLGA particles. The gradual release of loaded antigens from PLGA particles is necessary for the induction of efficient immunity. Various factors can influence protein release rates from PLGA particles, which can be defined intrinsic features of the polymer, particle characteristics as well as protein and environmental related factors. The use of PLGA particles encapsulating antigens of different diseases such as hepatitis B, tuberculosis, chlamydia, malaria, leishmania, toxoplasma and allergy antigens will be described herein. The co-delivery of antigens and immunostimulants (IS) with PLGA particles can prevent the systemic adverse effects of immunopotentiators and activate both dendritic cells (DCs) and natural killer (NKs) cells, consequently enhancing the therapeutic efficacy of antigen-loaded PLGA particles. We will review co-delivery of different TLR ligands with antigens in various models, highlighting the specific strengths and weaknesses of the system. Strategies to enhance the immunotherapeutic effect of DC-based vaccine using PLGA particles can be designed to target DCs by functionalized PLGA particle encapsulating siRNAs of suppressive gene, and disease specific antigens. Finally, specific examples of cellular targeting where decorating the surface of PLGA particles target orally administrated vaccine to M-cells will be highlighted. PMID:26513024

Effects of Macroporous Resin Size on Candida antarctica Lipase B Adsorption, Fraction of Active Molecules, and Catalytic Activity for Polyester Synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen,B.; Miller, E.; Miller, L.

2007-01-01

Methyl methacrylate resins with identical average pore diameter (250 {angstrom}) and surface area (500 m{sup 2}/g) but with varied particle size (35 to 560-710 {mu}m) were employed to study how immobilization resin particle size influences Candida antarctica Lipase B (CALB) loading, fraction of active sites, and catalytic properties for polyester synthesis. CALB adsorbed more rapidly on smaller beads. Saturation occurred in less than 30 s and 48 h for beads with diameters 35 and 560-710 {mu}m, respectively. Linearization of adsorption isotherm data by the Scatchard analysis showed for the 35 {mu}m resin that: (1) CALB loading at saturation was wellmore » below that required to form a monolayer and fully cover the support surface and (2) CALB has a high affinity for this resin surface. Infrared microspectroscopy showed that CALB forms protein loading fronts for resins with particle sizes 560-710 and 120 {mu}m. In contrast, CALB appears evenly distributed throughout 35 {mu}m resins. By titration with p-nitrophenyl n-hexyl phosphate (MNPHP), the fraction of active CALB molecules adsorbed onto resins was <50% which was not influenced by particle size. The fraction of active CALB molecules on the 35 {mu}m support increased from 30 to 43% as enzyme loading was increased from 0.9 to 5.7% (w/w) leading to increased activity for {epsilon}-caprolactone ({epsilon}-CL) ring-opening polymerization. At about 5% w/w CALB loading, by decreasing the immobilization support diameter from 560-710 to 120, 75, and 35 {mu}m, conversion of {epsilon}-CL % to polyester increased (20 to 36, 42, and 61%, respectively, at 80 min). Similar trends were observed for condensation polymerizations between 1,8-octanediol and adipic acid.« less

An Experimental Study of Hafting Adhesives and the Implications for Compound Tool Technology

PubMed Central

Zipkin, Andrew M.; Wagner, Mark; McGrath, Kate; Brooks, Alison S.; Lucas, Peter W.

2014-01-01

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns. PMID:25383871

An experimental study of hafting adhesives and the implications for compound tool technology.

PubMed

Zipkin, Andrew M; Wagner, Mark; McGrath, Kate; Brooks, Alison S; Lucas, Peter W

2014-01-01

Experimental studies of hafting adhesives and modifications to compound tool components can demonstrate the extent to which human ancestors understood and exploited material properties only formally defined by science within the last century. Discoveries of Stone Age hafting adhesives at archaeological sites in Europe, the Middle East, and Africa have spurred experiments that sought to replicate or create models of such adhesives. Most of these studies, however, have been actualistic in design, focusing on replicating ancient applications of adhesive technology. In contrast, this study tested several glues based on Acacia resin within a materials science framework to better understand the effect of each adhesive ingredient on compound tool durability. Using an overlap joint as a model for a compound tool, adhesives formulated with loading agents from a range of particle sizes and mineral compositions were tested for toughness on smooth and rough substrates. Our results indicated that overlap joint toughness is significantly increased by using a roughened joint surface. Contrary to some previous studies, there was no evidence that particle size diversity in a loading agent improved adhesive effectiveness. Generally, glues containing quartz or ochre loading agents in the silt and clay-sized particle class yielded the toughest overlap joints, with the effect of particle size found to be more significant for rough rather than smooth substrate joints. Additionally, no particular ochre mineral or mineral mixture was found to be a clearly superior loading agent. These two points taken together suggest that Paleolithic use of ochre-loaded adhesives and the criteria used to select ochres for this purpose may have been mediated by visual and symbolic considerations rather than purely functional concerns.

Fabrication and characterization of novel antimicrobial films derived from thymol-loaded zein-sodium caseinate (SC) nanoparticles.

PubMed

Li, Kang-Kang; Yin, Shou-Wei; Yang, Xiao-Quan; Tang, Chuan-He; Wei, Zi-Hao

2012-11-21

The objective of this research was to fabricate novel antimicrobial films based on zein colloidal nanoparticles coated with sodium caseinate (SC), an emulsifier/stabilizer. Thymol-loaded zein-SC nanoparticles were prepared using an antisolvent technique, with the average particle size and zeta potential about 200 ± 20 nm and -40 mV, respectively. Zein-SC nanoparticle-based films exhibited higher mechanical resistance and water barrier capacity than the SC films and concomitant good extensibility as compared with zein films. Thymol loadings endowed zein-SC nanoparticle-based films with antimicrobial activity against Escherichia coli and Salmonella as well as DPPH radical scavenging activity. Water vapor permeability, microstructure, mechanical, and controlled release properties of the films were evaluated. The possible relationship between some selected physical properties and microstructure were also discussed. Atomic force microscopy (AFM) analysis indicated that thymol loadings resulted in the emergence phenomena of the nanoparticles to form large particles or packed structure, consisting of clusters of nanoparticles, within the film matrix, in a thymol loading dependent manner. The appearance of large particles or an agglomerate of particles may weaken the compactness of protein network of films and thus impair the water barrier capacity, mechanical resistance, and extensibility of the films. The release kinetics of thymol from nanoparticle-based films can be described as a two-step biphasic process, that is, an initial burst effect followed by subsequent slower release, and zein-SC nanoparticles within the films matrices gave them the ability to sustain the release of thymol. In addition, a schematic illustration of the formation pathway of zein-SC nanoparticle-based films with or without thymol was proposed to illuminate the possible relationship between some selected physical properties and the microstructure of the films.

Poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) as a drug delivery vehicle for hydrophobic drugs.

PubMed

Bailly, Nathalie; Thomas, Mark; Klumperman, Bert

2012-12-10

Poly((N-vinylpyrrolidone)-block-poly(vinyl acetate)) (PVP-b-PVAc) block copolymers of varying molecular weight and hydrophobic block lengths were synthesized via controlled radical polymerization and investigated as carriers for the solubilization of highly hydrophobic riminophenazine compounds. These compounds have recently been shown to exhibit a strong activity against a variety of cancer types. PVP-b-PVAc self-assembles into polymer vesicles in aqueous media, and the dialysis method was used to load the water-insoluble drug (clofazimine) into these polymer vesicles. The polymer vesicles were characterized by 1H NMR spectroscopy to confirm vesicle formation and the incorporation of the anticancer drugs into the polymer vesicles. Dynamic light scattering was used to determine the particle size and particle size distribution of the drug-loaded vesicles as well as the stability of the vesicles under physiological conditions. The size of the polymer vesicles did not increase upon loading with clofazimine, and the particle size of 180-200 nm and the narrow particle size distribution were maintained. The morphology of the vesicles was examined by transmission electron microscopy. The polymer vesicles had a relatively high drug loading capacity of 20 wt %. In vitro cytotoxicity studies of PVP-b-PVAc and drug-loaded PVP-b-PVAc were performed against MDA-MB-231 multidrug-resistant breast epithelial cancer cells and MCF12A nontumorigenic breast epithelial cells. In vitro experiments demonstrated that the PVP-b-PVAc drug carrier showed no cytotoxicity, which confirms the biocompatibility of the PVP-b-PVAc drug carrier. The results indicate that the present PVP-b-PVAc block copolymer could be a potential candidate as a drug carrier for hydrophobic drugs.

Photoresponsive cross-linked polymeric particles for phototriggered burst release.

PubMed

Wang, Zhen; Yu, Lili; Lv, Cong; Wang, Peng; Chen, Yedong; Tang, Xinjing

2013-01-01

We synthesized a series of cross-linked photoresponsive polymeric particles with photolabile monomers and cross-linkers through miniemulsion polymerization. These particles are quite stable in dark, while light irradiation caused the breakage of particles and the efficient release of encapsulated contents up to 95% based on Nile red fluorescence. Photoswitches of particle systems were confirmed by fluorescence spectroscopy, SEM and colorimetry. Particle uptake and triggered release in RAW264.7 cells were confirmed by fluorescein diacetate loaded particles. © 2013 The Authors. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Attrition of limestone by impact loading in fluidized beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fabrizio Scala; Fabio Montagnaro; Piero Salatino

2007-09-15

The present study addresses limestone attrition and fragmentation associated with impact loading, a process which may occur extensively in various regions of fluidized bed (FB) combustors/gasifiers, primarily the jetting region of the bottom bed, the exit region of the riser, and the cyclone. An experimental protocol for the characterization of the propensity of limestone to undergo attrition/fragmentation by impact loading is reported. The application of the protocol is demonstrated with reference to an Italian limestone whose primary fragmentation and attrition by surface wear have already been characterized in previous studies. The experimental procedure is based on the characterization of themore » amount and particle size distribution of the debris generated upon the impact of samples of sorbent particles against a target. Experiments were carried out at a range of particle impact velocities between 10 and 45 m/s, consistent with jet velocities corresponding to typical pressure drops across FB gas distributors. The protocol has been applied to either raw or preprocessed limestone samples. In particular, the effect of calcination, sulfation, and calcination/recarbonation cycles on the impact damage suffered by sorbent particles has been assessed. The measurement of particle voidage and pore size distribution by mercury intrusion was also accomplished to correlate fragmentation with the structural properties of the sorbent samples. Fragmentation by impact loading of the limestone is significant. Lime displays the largest propensity to undergo impact damage, followed by the sorbent sulfated to exhaustion, the recarbonated sorbent, and the raw limestone. Fragmentation of the raw limestone and of the sulfated lime follows a pattern typical of the failure of brittle materials. The fragmentation behavior of lime and recarbonated lime better conforms to a disintegration failure mode, with an extensive generation of very fine fragments. 27 refs., 9 figs. 1 tab.« less

Effect of filler loading and silane modification on the biodegradability of SBR composites reinforced with peanut shell powder

NASA Astrophysics Data System (ADS)

Shaniba, V.; Balan, Aparna K.; Sreejith, M. P.; Jinitha, T. V.; Subair, N.; Purushothaman, E.

2017-06-01

The development of biocomposites and their applications are important in material science due to environmental and sustainability issues. The extent of degradation depends on the nature of reinforcing filler, particle size and their modification. In this article, we tried to focus on the biodegradation of composites of Styrene Butadiene Rubber (SBR) reinforced with Peanut Shell Powder (PSP) by soil burial test. The composites of SBR with untreated PSP (UPSP) and silane modified PSP (SPSP) of 10 parts per hundred rubber (phr) and 20 phr filler loading in two particle size were buried in the garden soil for six months. The microbial degradation were assessed through the measurement of weight loss, tensile strength and hardness at definite period. The study shows that degradation increases with increase in filler loading and particle size. The chemical treatment of filler has been found to resist the degradation. The analysis of morphological properties by the SEM also confirmed biodegradation process by the microorganism in the soil.

Effects of formulation variables and characterization of guaifenesin wax microspheres for controlled release.

PubMed

Mani, Narasimhan; Park, M O; Jun, H W

2005-01-01

Sustained-release wax microspheres of guaifenesin, a highly water-soluble drug, were prepared by the hydrophobic congealable disperse method using a salting-out procedure. The effects of formulation variables on the loading efficiency, particle properties, and in-vitro drug release from the microspheres were determined. The type of dispersant, the amount of wetting agent, and initial stirring time used affected the loading efficiency, while the volume of external phase and emulsification speed affected the particle size of the microspheres to a greater extent. The crystal properties of the drug in the wax matrix and the morphology of the microspheres were studied by differential scanning calorimetry (DSC), powder x-ray diffraction (XRD), and scanning electron microscopy (SEM). The DSC thermograms of the microspheres showed that the drug lost its crystallinity during the microencapsulation process, which was further confirmed by the XRD data. The electron micrographs of the drug-loaded microspheres showed well-formed spherical particles with a rough exterior.

Degradation of Li/S Battery Electrodes On 3D Current Collectors Studied Using X-ray Phase Contrast Tomography

PubMed Central

Zielke, L.; Barchasz, C.; Waluś, S.; Alloin, F.; Leprêtre, J.-C.; Spettl, A.; Schmidt, V.; Hilger, A.; Manke, I.; Banhart, J.; Zengerle, R.; Thiele, S.

2015-01-01

Lithium/sulphur batteries are promising candidates for future energy storage systems, mainly due to their high potential capacity. However low sulphur utilization and capacity fading hinder practical realizations. In order to improve understanding of the system, we investigate Li/S electrode morphology changes for different ageing steps, using X-ray phase contrast tomography. Thereby we find a strong decrease of sulphur loading after the first cycle, and a constant loading of about 15% of the initial loading afterwards. While cycling, the mean sulphur particle diameters decrease in a qualitatively similar fashion as the discharge capacity fades. The particles spread, migrate into the current collector and accumulate in the upper part again. Simultaneously sulphur particles lose contact area with the conducting network but regain it after ten cycles because their decreasing size results in higher surface areas. Since the capacity still decreases, this regain could be associated with effects such as surface area passivation and increasing charge transfer resistance. PMID:26043280

Degradation of Li/S Battery Electrodes On 3D Current Collectors Studied Using X-ray Phase Contrast Tomography

NASA Astrophysics Data System (ADS)

Zielke, L.; Barchasz, C.; Waluś, S.; Alloin, F.; Leprêtre, J.-C.; Spettl, A.; Schmidt, V.; Hilger, A.; Manke, I.; Banhart, J.; Zengerle, R.; Thiele, S.

2015-06-01

Lithium/sulphur batteries are promising candidates for future energy storage systems, mainly due to their high potential capacity. However low sulphur utilization and capacity fading hinder practical realizations. In order to improve understanding of the system, we investigate Li/S electrode morphology changes for different ageing steps, using X-ray phase contrast tomography. Thereby we find a strong decrease of sulphur loading after the first cycle, and a constant loading of about 15% of the initial loading afterwards. While cycling, the mean sulphur particle diameters decrease in a qualitatively similar fashion as the discharge capacity fades. The particles spread, migrate into the current collector and accumulate in the upper part again. Simultaneously sulphur particles lose contact area with the conducting network but regain it after ten cycles because their decreasing size results in higher surface areas. Since the capacity still decreases, this regain could be associated with effects such as surface area passivation and increasing charge transfer resistance.

Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: a case study with itraconazole and ibuprofen.

PubMed

Mellaerts, Randy; Jammaer, Jasper A G; Van Speybroeck, Michiel; Chen, Hong; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy; Martens, Johan A

2008-08-19

The ordered mesoporous silica material SBA-15 was loaded with the model drugs itraconazole and ibuprofen using three different procedures: (i) adsorption from solution, (ii) incipient wetness impregnation, and (iii) heating of a mixture of drug and SBA-15 powder. The location of the drug molecules in the SBA-15 particles and molecular interactions were investigated using nitrogen adsorption, TGA, DSC, DRS UV-vis, and XPS. The in vitro release of hydrophobic model drugs was evaluated in an aqueous environment simulating gastric fluid. The effectiveness of the loading method was found to be strongly compound dependent. Incipient wetness impregnation using a concentrated itraconazole solution in dichloromethane followed by solvent evaporation was most efficient for dispersing itraconazole in SBA-15. The itraconazole molecules were located on the mesopore walls and inside micropores of the mesopore walls. When SBA-15 was loaded by slurrying it in a diluted itraconazole solution from which the solvent was evaporated, the itraconazole molecules ended up in the mesopores that they plugged locally. At a loading of 30 wt %, itraconazole exhibited intermolecular interactions inside the mesopores revealed by UV spectroscopy and endothermic events traced with DSC. The physical mixing of itraconazole and SBA-15 powder followed by heating above the itraconazole melting temperature resulted in formulations in which glassy itraconazole particles were deposited externally on the SBA-15 particles. Loading with ibuprofen was successful with each of the three loading procedures. Ibuprofen preferably is positioned inside the micropores. In vitro release experiments showed fast release kinetics provided the drug molecules were evenly deposited over the mesoporous surface.

TRACE METAL LOADING ON WATERBORNE SOIL AND DUST PARTICLES CHARACTERIZED THROUGH THE USE OF SPLIT-FLOW THIN CELL FRACTIONATION

EPA Science Inventory

The fate and transport of metallic pollutants through a watershed are related to the characteristics of undissolved solid particles to which they are bound. Removal of these particles and their associated pollutants via engineered structures such as settling ponds i one goal of s...

Visible light curing of Epon SU-8 based superparamagnetic polymer composites with random and ordered particle configurations.

PubMed

Peters, Christian; Ergeneman, Olgaç; Sotiriou, Georgios A; Choi, Hongsoo; Nelson, Bradley J; Hierold, Christofer

2015-01-14

The performance of superparamagnetic polymer composite microdevices is highly dependent on the magnetic particle content. While high loading levels are desired for many applications, the UV absorption of these nanoparticles limits the overall thickness of the fabricated microstructures and subsequently their capability of magnetic interaction. The combination of a visible-light-sensitive photoinitiator and particle self-organization is proposed to extend the exposure depth limitation in Epon SU-8 based superparamagnetic polymer composites. While superparamagnetic iron oxide particles strongly absorb i-line radiation required to cross-link the Epon SU-8 polymer matrix, we propose the utilization of H-Nu 470 photoinitiator to expand the photosensitivity of the composite toward the visible spectrum, where the dispersed nanoparticles are more transparent. The novel photoinitiator preserves the composite's superparamagnetic properties as well as a homogeneous particle distribution. As a result, particle load or resist thickness can be more than doubled while maintaining exposure time. The self-organization of ordered magnetic structures allows for an additional increase in exposure depth of up to 40%, resulting in a 2.5-fold saturation magnetization.

Strength of anisotropy in a granular material: Linear versus nonlinear contact model

NASA Astrophysics Data System (ADS)

La Ragione, Luigi; Gammariello, Marica; Recchia, Giuseppina

2016-12-01

In this paper, we deal with anisotropy in an idealized granular material made of a collection of frictional, elastic, contacting particles. We present a theoretical analysis for an aggregate of particles isotropically compressed and then sheared, in which two possible contacts laws between particles are considered: a linear contact law, where the contact stiffness is constant; and a nonlinear contact law, where the contact stiffness depends on the overlapping between particles. In the former case the anisotropy observed in the aggregate is associated with particle arrangement. In fact, although the aggregate is initially characterized by an isotropic network of contacts, during the loading, an anisotropic texture develops, which is measured by a fabric tensor. With a nonlinear contact law it is possible to develop anisotropy because contacting stiffnesses are different, depending on the orientation of the contact vectors with respect to the axis of the applied deformation. We find that before the peak load is reached, an aggregate made of particles with a linear contact law develops a much smaller anisotropy compared with that of an aggregate with a nonlinear law.

Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms.

PubMed

Goyat, M S; Rana, S; Halder, Sudipta; Ghosh, P K

2018-01-01

Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO 2 ) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (T g ) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation. Copyright © 2017 Elsevier B.V. All rights reserved.

Quercetin loaded biopolymeric colloidal particles prepared by simultaneous precipitation of quercetin with hydrophobic protein in aqueous medium.

PubMed

Patel, Ashok R; Heussen, Patricia C M; Hazekamp, Johan; Drost, Ellen; Velikov, Krassimir P

2012-07-15

Quercetin loaded biopolymeric colloidal particles were prepared by precipitating quercetin (water insoluble polyphenol) and zein (hydrophobic protein), simultaneously, by adding their hydro-alcoholic solution to aqueous solution in presence of sodium caseinate as an electrosteric stabiliser. The presence of protein resulted in altering the shape of quercetin precipitates from needle-like to spherical shape at higher zein proportions, as confirmed by transmission electron microscopy. The average particle size of zein:quercetin composite particles was below 200 nm (130-161 nm) with negative surface charge (-30 to -41 mV), as confirmed by dynamic light scattering and electrophoretic mobility data. Solid state characterisation (X-ray diffraction) and spectroscopic measurements (UV-Vis and IR spectroscopy) confirmed characteristic changes in quercetin due to the entrapment in the biopolymeric matrix of colloidal particles. Results from anti-oxidant study demonstrated the advantage of entrapping quercetin in the colloidal particles in terms of the chemical stability in the alkaline pH and against photodegradation under UV-light irradiation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Tailoring MCM-41 mesoporous silica particles through modified sol-gel process for gas separation

NASA Astrophysics Data System (ADS)

Sang, Wong Yean; Ching, Oh Pei

2017-10-01

Mobil Composition of Matter-41 (MCM-41) is recognized as a potential filler to enhance permeability of mixed matrix membrane (MMM). However, the required loading for available micron-sized MCM-41 was considerably high in order to achieve desired separation performance. In this work, reduced-size MCM-41 was synthesized to minimize filler loading, improve surface modification and enhance polymer-filler compatibility during membrane fabrication. The effect of reaction condition, stirring rate and type of post-synthesis washing solution used on particle diameter of resultant MCM-41 were investigated. It was found that MCM-41 produced at room temperature condition yield particles with smaller diameter, higher specific surface area and enhanced mesopore structure. Increase of stirring rate up to 500 rpm during synthesis also reduced the particle diameter. In addition, replacing water with methanol as the post-synthesis washing solution to remove bromide ions from the precipitate was able to further reduce the particle size by inhibiting polycondensation reaction.

Non-biodegradable polymer particles for drug delivery: A new technology for "bio-active" restorative materials.

PubMed

Imazato, Satoshi; Kitagawa, Haruaki; Tsuboi, Ririko; Kitagawa, Ranna; Thongthai, Pasiree; Sasaki, Jun-Ichi

2017-09-26

To develop dental restorative materials with "bio-active" functions, addition of the capability to release active agents is an effective approach. However, such functionality needs to be attained without compromising the basic properties of the restorative materials. We have developed novel non-biodegradable polymer particles for drug delivery, aimed for application in dental resins. The particles are made using 2-hydroxyethyl methacrylate (HEMA) and a cross-linking monomer trimethylolpropane trimethacrylate (TMPT), with a hydrophilic nature to adsorb proteins or water-soluble antimicrobials. The polyHEMA/TMPT particles work as a reservoir to release fibroblast growth factor-2 (FGF-2) or cetylpyridinium chloride (CPC) in an effective manner. Application of the polyHEMA/TMPT particles loaded with FGF-2 to adhesives, or those loaded with CPC to resin-based endodontic sealers or denture bases/crowns is a promising approach to increase the success of the treatments by conferring "bio-active" properties to these materials to induce tissue regeneration or to inhibit bacterial infection.

Mercury in sediment, water, and fish in a managed tropical wetland-lake ecosystem.

PubMed

Malczyk, Evan A; Branfireun, Brian A

2015-08-15

Mercury pollution has not been well documented in the inland lakes or fishes of Mexico, despite the importance of freshwater fish as a source of protein in local diets. Total mercury and methylmercury in waters, sediments, and the commercial fish catch were investigated in Lake Zapotlán, Mexico. Concentrations of total and methylmercury were very high in runoff and wastewater inputs, but very low in sediments and surface waters of the open water area of the lake. Concentrations of total mercury in tilapia and carp were very low, consistent with the low concentrations in lake water and sediments. Particle settling, sorption, the biogeochemical environment, and/or bloom dilution are all plausible explanations for the significant reductions in both total mercury and methylmercury. Despite very high loading of mercury, this shallow tropical lake was not a mercury-impaired ecosystem, and these findings may translate across other shallow, alkaline tropical lakes. Importantly, the ecosystem services that seemed to be provided by peripheral wetlands in reducing mercury inputs highlight the potential for wetland conservation or restoration in Mexico. Copyright © 2015. Published by Elsevier B.V.

The Contribution of Oil Sands Industry Related Atmospheric THg and MeHg Deposition to Rivers of the Athabasca Oil Sands Region of Canada

NASA Astrophysics Data System (ADS)

Wasiuta, V. L.; Cooke, C. A.; Kirk, J.; Chambers, P. A.; Alexander, A. C.; Rooney, R. C.

2017-12-01

Rapid development of Oil Sands deposits in northern Alberta (Canada) raises concerns about human health and environmental impacts. We present results from a three-year study of winter-time atmospheric deposition of total mercury (THg) and methylmercury (MeHg) in six tributary watersheds of the Athabasca River. Seasonal snowpack THg and MeHg concentrations were obtained from spring-time sampling throughout the oil sands region. Winter-time Hg loads were then modeled at watershed and sub-basin scales using ArcGIS geostatistical kriging. To determine the potential impacts of snowmelt on aquatic ecosystems, six rivers were sampled at high frequency over 2012 to 2014 ice-free seasons. Hydrologic year (HY) and first discharge peak loads were then calculated from linear extrapolation of measured concentrations and mean daily discharge. Results showed high THg and MeHg loads from atmospheric deposition around regional upgrading facilities with loads diminishing outwards. This reflects the large proportion of particle bound Hg with a short atmospheric residence time, and deposition close to emission sources. Snowpacks within the six watersheds contained substantial proportions of tributary river THg and MeHg loads. For example, HY2014 snowpacks contained 24 to 46 % of river MeHg loads. All rivers showed a large proportion of HY loads discharged, within a few weeks, in the spring first discharge peak. HY2014 snowpack MeHg loads were greater than river loads in the first discharge peak for all watersheds except the High Hills. This first discharge peak is important as it occurs during critical growth periods for aquatic life. Large differences in tributary river THg and MeHg loads suggest factors other than atmospheric deposition and watershed scale contributed to the load. Considerably higher THg and MeHg snowpack loads in the Muskeg Watershed relative to river export suggest substantial losses to catchment soils or wetlands during snowmelt. Evaluation of factors that could contribute to the large differences in watershed Hg discharge, include proportion of wetlands along with different wetland classes, scale of industrial development, and development hydrologic connectivity. The consequence of long-term Hg loading to wetland ecosystems has yet to be assessed.

Subcritical water liquefaction of oil palm fruit press fiber in the presence of sodium hydroxide: an optimisation study using response surface methodology.

PubMed

Mazaheri, Hossein; Lee, Keat Teong; Bhatia, Subhash; Mohamed, Abdul Rahman

2010-12-01

Thermal decomposition of oil palm fruit press fiber (FPF) into a liquid product (LP) was achieved using subcritical water treatment in the presence of sodium hydroxide in a high pressure batch reactor. This study uses experimental design and process optimisation tools to maximise the LP yield using response surface methodology (RSM) with central composite rotatable design (CCRD). The independent variables were temperature, residence time, particle size, specimen loading, and additive loading. The mathematical model that was developed fit the experimental results well for all of the response variables that were studied. The optimal conditions were found to be a temperature of 551 K, a residence time of 40 min, a particle size of 710-1000 microm, a specimen loading of 5 g, and a additive loading of 9 wt.% to achieve a LP yield of 76.16%. 2010 Elsevier Ltd. All rights reserved.

Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid

PubMed Central

Subongkot, Thirapit; Ngawhirunpat, Tanasait

2017-01-01

This study was aimed to develop a novel microemulsion that contained oleth-5 as a surfactant to enhance the oral absorption of all-trans retinoic acid (ATRA). The prepared microemulsion was evaluated for its particle size, shape, zeta potential, in vitro release, in vitro intestinal absorption, intestinal membrane cytotoxicity and stability. The obtained microemulsion was spherical in shape with a particle size of <200 nm and a negative surface charge. The in vitro release of the ATRA-loaded microemulsion was best fit with the zero-order model. This microemulsion significantly improved the intestinal absorption of ATRA. Confocal laser scanning microscopy analysis using a fluorescent dye-loaded microemulsion also confirmed the intestinal absorption result. The intestinal membrane cytotoxicity of the ATRA-loaded microemulsion did not differ from an edible oil (fish oil). Stability testing showed that the ATRA-loaded microemulsion was more stable at 25°C than 40°C. PMID:28831254

Development of a novel microemulsion for oral absorption enhancement of all-trans retinoic acid.

PubMed

Subongkot, Thirapit; Ngawhirunpat, Tanasait

2017-01-01

This study was aimed to develop a novel microemulsion that contained oleth-5 as a surfactant to enhance the oral absorption of all-trans retinoic acid (ATRA). The prepared microemulsion was evaluated for its particle size, shape, zeta potential, in vitro release, in vitro intestinal absorption, intestinal membrane cytotoxicity and stability. The obtained microemulsion was spherical in shape with a particle size of <200 nm and a negative surface charge. The in vitro release of the ATRA-loaded microemulsion was best fit with the zero-order model. This microemulsion significantly improved the intestinal absorption of ATRA. Confocal laser scanning microscopy analysis using a fluorescent dye-loaded microemulsion also confirmed the intestinal absorption result. The intestinal membrane cytotoxicity of the ATRA-loaded microemulsion did not differ from an edible oil (fish oil). Stability testing showed that the ATRA-loaded microemulsion was more stable at 25°C than 40°C.

Traffic on complex networks: Towards understanding global statistical properties from microscopic density fluctuations

NASA Astrophysics Data System (ADS)

Tadić, Bosiljka; Thurner, Stefan; Rodgers, G. J.

2004-03-01

We study the microscopic time fluctuations of traffic load and the global statistical properties of a dense traffic of particles on scale-free cyclic graphs. For a wide range of driving rates R the traffic is stationary and the load time series exhibits antipersistence due to the regulatory role of the superstructure associated with two hub nodes in the network. We discuss how the superstructure affects the functioning of the network at high traffic density and at the jamming threshold. The degree of correlations systematically decreases with increasing traffic density and eventually disappears when approaching a jamming density Rc. Already before jamming we observe qualitative changes in the global network-load distributions and the particle queuing times. These changes are related to the occurrence of temporary crises in which the network-load increases dramatically, and then slowly falls back to a value characterizing free flow.

In-Situ X-ray Tomography Observation of Structure Evolution in 1,3,5-Triamino-2,4,6-Trinitrobenzene Based Polymer Bonded Explosive (TATB-PBX) under Thermo-Mechanical Loading.

PubMed

Yuan, Zeng-Nian; Chen, Hua; Li, Jing-Ming; Dai, Bin; Zhang, Wei-Bin

2018-05-04

In order to study the fracture behavior and structure evolution of 1,3,5-Triamino-2,4,6-Trinitrobenzene (TATB)-based polymer bonded explosive in thermal-mechanical loading, in-situ studies were performed on X-ray computed tomography system using quasi-static Brazilian test. The experiment temperature was set from −20 °C to 70 °C. Three-dimensional morphology of cracks at different temperatures was obtained through digital image process. The various fracture modes were compared by scanning electron microscopy. Fracture degree and complexity were defined to quantitatively characterize the different types of fractures. Fractal dimension was used to characterize the roughness of the crack surface. The displacement field of particles in polymer bonded explosive (PBX) was used to analyze the interior structure evolution during the process of thermal-mechanical loading. It was found that the brittleness of PBX reduced, the fracture got more tortuous, and the crack surface got smoother as the temperature rose. At lower temperatures, especially lower than glass transition temperature of binders, there were slipping and shear among particles, and particles tended to displace and disperse; while at higher temperatures, especially above the glass transition temperature of binders, there was reorganization of particles and particles tended to merge, disperse, and reduce sizes, rather than displacing.

Citrate- and Succinate-Modified Carbonate Apatite Nanoparticles with Loaded Doxorubicin Exhibit Potent Anticancer Activity against Breast Cancer Cells

PubMed Central

Mehbuba Hossain, Sultana; Chowdhury, Ezharul Hoque

2018-01-01

Biodegradable inorganic apatite-based particle complex is popular for its pH-sensitivity at the endosomal acidic environment to facilitate drug release following cellular uptake. Despite being a powerful anticancer drug, doxorubicin shows severe off-target effects and therefore would need a carrier for the highest effectiveness. We aimed to chemically modify carbonate apatite (CA) with Krebs cycle intermediates, such as citrate and succinate in order to control the growth of the resultant particles to more efficiently carry and transport the anticancer drug into the cancer cells. Citrate- or succinate-modified CA particles were synthesized with different concentrations of sodium citrate or sodium succinate, respectively, in the absence or presence of doxorubicin. The drug loading efficiency of the particles and their cellular uptake were observed by quantifying fluorescence intensity. The average diameter and surface charge of the particles were determined using Zetasizer. Cell viability was assessed by MTT assay. Citrate-modified carbonate apatite (CMCA) exhibited the highest (31.38%) binding affinity for doxorubicin and promoted rapid cellular uptake of the drug, leading to the half-maximal inhibitory concentration 1000 times less than that of the free drug in MCF-7 cells. Hence, CMCA nanoparticles with greater surface area enhance cytotoxicity in different breast cancer cells by enabling higher loading and more efficient cellular uptake of the drug. PMID:29534497

Effect of the relationship between particle size, inter-particle distance, and metal loading of carbon supported fuel cell catalysts on their catalytic activity

NASA Astrophysics Data System (ADS)

Corradini, Patricia Gon; Pires, Felipe I.; Paganin, Valdecir A.; Perez, Joelma; Antolini, Ermete

2012-09-01

The effect of the relationship between particle size ( d), inter-particle distance ( x i ), and metal loading ( y) of carbon supported fuel cell Pt or PtRu catalysts on their catalytic activity, based on the optimum d (2.5-3 nm) and x i / d (>5) values, was evaluated. It was found that for y < 30 wt%, the optimum values of both d and x i / d can be always obtained. For y ≥ 30 wt%, instead, the positive effect of a thinner catalyst layer of the fuel cell electrode than that using catalysts with y < 30 wt% is concomitant to a decrease of the effective catalyst surface area due to an increase of d and/or a decrease of x i / d compared to their optimum values, with in turns gives rise to a decrease in the catalytic activity. The effect of the x i / d ratio has been successfully verified by experimental results on ethanol oxidation on PtRu/C catalysts with same particle size and same degree of alloying but different metal loading. Tests in direct ethanol fuel cells showed that, compared to 20 wt% PtRu/C, the negative effect of the lower x i / d on the catalytic activity of 30 and 40 wt% PtRu/C catalysts was superior to the positive effect of the thinner catalyst layer.

Aerosolized Antimicrobial Agents Based on Degradable Dextran Nanoparticles Loaded with Silver Carbene Complexes

PubMed Central

Ornelas-Megiatto, Cátia; Shah, Parth N.; Wich, Peter R.; Cohen, Jessica L.; Tagaev, Jasur A.; Smolen, Justin A.; Wright, Brian D.; Panzner, Matthew J.; Youngs, Wiley J.; Fréchet, Jean M. J.; Cannon, Carolyn L.

2012-01-01

Degradable acetalated dextran (Ac-DEX) nanoparticles were prepared and loaded with a hydrophobic silver carbene complex (SCC) by a single-emulsion process. The resulting particles were characterized for morphology and size distribution using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The average particle size and particle size distribution were found to be a function of the ratio of the organic phase to the surfactant containing aqueous phase with a 1:5 volume ratio of Ac-DEX CH2Cl2 (organic): PBS (aqueous) being optimal for the formulation of nanoparticles with an average size of 100 ± 40 nm and a low polydispersity. The SCC loading was found to increase with an increase in the SCC quantity in the initial feed used during particle formulation up to 30% (w/w); however, the encapsulation efficiency was observed to be the best at a feed ratio of 20% (w/w). In vitro efficacy testing of the SCC loaded Ac-DEX nanoparticles demonstrated their activity against both Gram-negative and Gram-positive bacteria; the nanoparticles inhibited the growth of every bacterial species tested. As expected, a higher concentration of drug was required to inhibit bacterial growth when the drug was encapsulated within the nanoparticle formulations compared with the free drug illustrating the desired depot release. Compared with free drug, the Ac-DEX nanoparticles were much more readily suspended in an aqueous phase and subsequently aerosolized, thus providing an effective method of pulmonary drug delivery. PMID:23025592

Aerosolized antimicrobial agents based on degradable dextran nanoparticles loaded with silver carbene complexes.

PubMed

Ornelas-Megiatto, Cátia; Shah, Parth N; Wich, Peter R; Cohen, Jessica L; Tagaev, Jasur A; Smolen, Justin A; Wright, Brian D; Panzner, Matthew J; Youngs, Wiley J; Fréchet, Jean M J; Cannon, Carolyn L

2012-11-05

Degradable acetalated dextran (Ac-DEX) nanoparticles were prepared and loaded with a hydrophobic silver carbene complex (SCC) by a single-emulsion process. The resulting particles were characterized for morphology and size distribution using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The average particle size and particle size distribution were found to be a function of the ratio of the organic phase to the surfactant containing aqueous phase with a 1:5 volume ratio of Ac-DEX CH(2)Cl(2) (organic):PBS (aqueous) being optimal for the formulation of nanoparticles with an average size of 100 ± 40 nm and a low polydispersity. The SCC loading was found to increase with an increase in the SCC quantity in the initial feed used during particle formulation up to 30% (w/w); however, the encapsulation efficiency was observed to be the best at a feed ratio of 20% (w/w). In vitro efficacy testing of the SCC loaded Ac-DEX nanoparticles demonstrated their activity against both Gram-negative and Gram-positive bacteria; the nanoparticles inhibited the growth of every bacterial species tested. As expected, a higher concentration of drug was required to inhibit bacterial growth when the drug was encapsulated within the nanoparticle formulations compared with the free drug illustrating the desired depot release. Compared with free drug, the Ac-DEX nanoparticles were much more readily suspended in an aqueous phase and subsequently aerosolized, thus providing an effective method of pulmonary drug delivery.

Distribution and chemistry of suspended particles from an active hydrothermal vent site on the Mid-Atlantic Ridge at 26°N

NASA Astrophysics Data System (ADS)

Trocine, Robert P.; Trefry, John H.

1988-04-01

Suspended particles were collected from an area of active hydrothermal venting at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge and analyzed for Fe, Mn, Cd, Zn, Cu, V, Ni, Cr, Pb, Mg, Ca, Al and Si. Rapid advection of vent-derived precipitates produced a lens with total suspended matter (TSM) loadings of 14-60 μg/l at 200-700 m above the seafloor; TSM concentrations > 60 μg/l were observed only at near-vent sites. The distribution of suspended particles correlated well with increased dissolved Mn concentrations and particulate Fe values near the vent source. Particulate Fe values decreased linearly relative to TSM concentrations as hydrothermal precipitates mixed with background suspended matter. Near-vent precipitates were characterized by up to 35% Fe, 2% Zn, 0.6% Cu and > 100 μg/g Cd. In comparison to Fe, particulate Cd, Zn and Cu values decreased dramatically away from the vent source. This trend supports differential settling and/or dissolution of Cd-, Zn- and Cu-bearing phases. Particulate Mn and Fe values were inversely related with only 50 μg Mn/g in the near-vent particles. At near-vent sites, > 99% of the total Mn was in solution; this fraction decreased to 75-80% at background TSM values. In contrast to Cd, Zn and Cu, particulate V levels show a continuous, linear decrease with particulate Fe values. This trend is explained by adsorption of V on Fe-oxides in the vent plume. Scavenging of Cr, Pb and Mg by hydrothermal precipitates is also suggested by the data. Nickel and Al values were low in near-vent particles at < 100 and < 3 μg/g, respectively. The complementary behavior of dissolved Mn and particulate trace metals provides a useful framework for studying broad aspects of hydrothermal plume processes.

A comparative study of the grain-size distribution of surface dust and stormwater runoff quality on typical urban roads and roofs in Beijing, China.

PubMed

Shen, Zhenyao; Liu, Jin; Aini, Guzhanuer; Gong, Yongwei

2016-02-01

The deposition of pollutants on impervious surfaces is a serious problem associated with rapid urbanization, which results in non-point-source pollution. Characterizing the build-up and wash-off processes of pollutants in urban catchments is essential for urban planners. In this paper, the spatial variation and particle-size distributions of five heavy metals and two nutrients in surface dust were analyzed, and the runoff water first-flush effect (FF30) and event-mean concentrations (EMCs) of 10 common constituents were characterized. The relationships between runoff variables and stormwater characteristics were examined from three typical urban impervious surfaces in Beijing, China. Dust on road surfaces with smaller grain sizes had higher pollutant concentrations, whereas concentrations of Mn, Zn, Fe, and TP in roof surface dust increased with grain size. Particles with grain sizes of 38-74 and 125-300 μm contributed most to the total pollutant load in roads, while particles with the smallest grain sizes (<38 μm) contributed most on roofs (23.46-41.71 %). Event-mean concentrations (EMCs) and FF30 values for most runoff pollutants tended to be higher on roofs than on roads. The maximum intensity (I max) and the antecedent dry days (ADD) were critical parameters for EMCs in roads, while ADD was the only dominant parameter for EMCs on our studied roof. The rainfall intensity (RI) and maximum intensity (I max) were found to be the parameters with the strongest correlation to the first-flush effect on both roads and roofs. Significant correlations of total suspended solids (TSS) concentration in runoff with grain-size fractions of surface dust indicated that coarser particles (74-300 μm) are most likely to contribute to the solid-phase pollutants, and finer particles (<38 μm) are likely the main source of dissolved pollutants.

Wear of liquid nitrogen-cooled 440C bearing steels in an oxygen environment

NASA Technical Reports Server (NTRS)

Chaudhuri, Dilip K.; Verma, Ravi

1988-01-01

This paper presents up-to-date findings of the research being conducted to understand the mechanism of sliding wear in unlubricated 440C bearing steels under oxidative conditions. A sliding wear test rig has been designed and built with a cylinder-on-flat geometry. The equipment is capable of testing specimens under high axial loads and sliding speeds in a simulated LOX environment. Samples of 440C steel, quenched and tempered to a hardness of Rc 56, were tested under a load of 890 N and a sliding speed of 2.05 m/sec for total sliding distances of up to 5.54 km. Flash temperatures during these tests were measured with an IR camera and a fast digital recorder. Microstructural and microanalytical data from the worn surfaces and the debris particles are analyzed extensively, along with wear rates, flash temperatures, surface profiles, hardnesses, and residual stresses, in the context of oxidation and wear theories.

Olive oil increases the magnitude of postprandial chylomicron remnants compared to milk fat and safflower oil.

PubMed

Higashi, K; Ishikawa, T; Shige, H; Tomiyasu, K; Yoshida, H; Ito, T; Nakajima, K; Yonemura, A; Sawada, S; Nakamura, H

1997-10-01

The acute effects of olive oil, milk fat and safflower oil on postprandial lipemia and remnant lipoprotein metabolism were investigated. Eight Healthy male volunteers randomly underwent three types of oral fat-vitamin A loading tests. The test drink was a mixture of retinyl palmitate (RP)(50,000 IU of aqueous vitamin A/m2 body surface area) and one of the three types of oils (40 g of fat/m2 body surface area): olive oil (70.7% oleic acid of total fatty acids); milk fat (69.3% saturated fatty acid); safflower oil (74.2% linoleic acid). Olive oil significantly increased plasma triacylglycerol and RP concentrations 4 hours after fat loading, as compared to other fats. Increases of remnant like particle concentrations were higher after olive oil than after the other two fats. These results show that olive oil increases the magnitude of postprandial chylomicrons and chylomicron remnants compared to milk fat and safflower oil.

Parking Lot Runoff Quality and Treatment Efficiency of a Stormwater-Filtration Device, Madison, Wisconsin, 2005-07

USGS Publications Warehouse

Horwatich, Judy A.; Bannerman, Roger T.

2010-01-01

To evaluate the treatment efficiency of a stormwater-filtration device (SFD) for potential use at Wisconsin Department of Transportation (WisDOT) park-and-ride facilities, a SFD was installed at an employee parking lot in downtown Madison, Wisconsin. This type of parking lot was chosen for the test site because the constituent concentrations and particle-size distributions (PSDs) were expected to be similar to those of a typical park-and-ride lot operated by WisDOT. The objective of this particular installation was to reduce loads of total suspended solids (TSS) in stormwater runoff to Lake Monona. This study also was designed to provide a range of treatment efficiencies expected for a SFD. Samples from the inlet and outlet were analyzed for 33 organic and inorganic constituents, including 18 polycyclic aromatic hydrocarbons (PAHs). Samples were also analyzed for physical properties, including PSD. Water-quality samples were collected for 51 runoff events from November 2005 to August 2007. Samples from all runoff events were analyzed for concentrations of suspended sediment (SS). Samples from 31 runoff events were analyzed for 15 constituents, samples from 15 runoff events were analyzed for PAHs, and samples from 36 events were analyzed for PSD. The treatment efficiency of the SFD was calculated using the summation of loads (SOL) and the efficiency ratio methods. Constituents for which the concentrations and (or) loads were decreased by the SFD include TSS, SS, volatile suspended solids, total phosphorous (TP), total copper, total zinc, and PAHs. The efficiency ratios for these constituents are 45, 37, 38, 55, 22, 5, and 46 percent, respectively. The SOLs for these constituents are 32, 37, 28, 36, 23, 8, and 48 percent, respectively. The SOL for chloride was -21 and the efficiency ratio was -18. Six chemical constituents or properties-dissolved phosphorus, chemical oxygen demand, dissolved zinc, total dissolved solids, dissolved chemical oxygen demand, and dissolved copper-were not included in the efficiency or SOL, because the difference between concentrations in samples from the inlet and outlet were not significant. Concentrations of TP and TSS were inexplicably high in samples at the inlet for one event.

Metal nanoparticle inks

DOEpatents

Lewis, Jennifer A [Urbana, IL; Ahn, Bok Yeop [Champaign, IL; Duoss, Eric B [Urbana, IL

2011-04-12

Stabilized silver particles comprise particles comprising silver, a short-chain capping agent adsorbed on the particles, and a long-chain capping agent adsorbed on the particles. The short-chain capping agent is a first anionic polyelectrolyte having a molecular weight (Mw) of at most 10,000, and the long-chain capping agent is a second anionic polyelectrolyte having a molecular weight (Mw) of at least 25,000. The stabilized silver particles have a solid loading of metallic silver of at least 50 wt %.

Specifically targeted delivery of protein to phagocytic macrophages

PubMed Central

Yu, Min; Chen, Zeming; Guo, Wenjun; Wang, Jin; Feng, Yupeng; Kong, Xiuqi; Hong, Zhangyong

2015-01-01

Macrophages play important roles in the pathogenesis of various diseases, and are important potential therapeutic targets. Furthermore, macrophages are key antigen-presenting cells and important in vaccine design. In this study, we report on the novel formulation (bovine serum albumin [BSA]-loaded glucan particles [GMP-BSA]) based on β-glucan particles from cell walls of baker’s yeast for the targeted delivery of protein to macrophages. Using this formulation, chitosan, tripolyphosphate, and alginate were used to fabricate colloidal particles with the model protein BSA via electrostatic interactions, which were caged and incorporated BSA very tightly within the β-glucan particle shells. The prepared GMP-BSA exhibited good protein-release behavior and avoided protein leakage. The particles were also highly specific to phagocytic macrophages, such as Raw 264.7 cells, primary bone marrow-derived macrophages, and peritoneal exudate macrophages, whereas the particles were not taken up by nonphagocytic cells, including NIH3T3, AD293, HeLa, and Caco-2. We hypothesize that these tightly encapsulated protein-loaded glucan particles deliver various types of proteins to macrophages with notably high selectivity, and may have broad applications in targeted drug delivery or vaccine design against macrophages. PMID:25784802

Explosive particle soil surface dispersion model for detonated military munitions.

PubMed

Hathaway, John E; Rishel, Jeremy P; Walsh, Marianne E; Walsh, Michael R; Taylor, Susan

2015-07-01

The accumulation of high explosive mass residue from the detonation of military munitions on training ranges is of environmental concern because of its potential to contaminate the soil, surface water, and groundwater. The US Department of Defense wants to quantify, understand, and remediate high explosive mass residue loadings that might be observed on active firing ranges. Previously, efforts using various sampling methods and techniques have resulted in limited success, due in part to the complicated dispersion pattern of the explosive particle residues upon detonation. In our efforts to simulate particle dispersal for high- and low-order explosions on hypothetical firing ranges, we use experimental particle data from detonations of munitions from a 155-mm howitzer, which are common military munitions. The mass loadings resulting from these simulations provide a previously unattained level of detail to quantify the explosive residue source-term for use in soil and water transport models. In addition, the resulting particle placements can be used to test, validate, and optimize particle sampling methods and statistical models as applied to firing ranges. Although the presented results are for a hypothetical 155-mm howitzer firing range, the method can be used for other munition types once the explosive particle characteristics are known.

Method for improving instrument response

DOEpatents

Hahn, David W.; Hencken, Kenneth R.; Johnsen, Howard A.; Flower, William L.

2000-01-01

This invention pertains generally to a method for improving the accuracy of particle analysis under conditions of discrete particle loading and particularly to a method for improving signal-to-noise ratio and instrument response in laser spark spectroscopic analysis of particulate emissions. Under conditions of low particle density loading (particles/m.sup.3) resulting from low overall metal concentrations and/or large particle size uniform sampling can not be guaranteed. The present invention discloses a technique for separating laser sparks that arise from sample particles from those that do not; that is, a process for systematically "gating" the instrument response arising from "sampled" particles from those responses which do not, is dislosed as a solution to his problem. The disclosed approach is based on random sampling combined with a conditional analysis of each pulse. A threshold value is determined for the ratio of the intensity of a spectral line for a given element to a baseline region. If the threshold value is exceeded, the pulse is classified as a "hit" and that data is collected and an average spectrum is generated from an arithmetic average of "hits". The true metal concentration is determined from the averaged spectrum.

Separation of HIV-1 gag virus-like particles from vesicular particles impurities by hydroxyl-functionalized monoliths.

PubMed

Steppert, Petra; Burgstaller, Daniel; Klausberger, Miriam; Kramberger, Petra; Tover, Andres; Berger, Eva; Nöbauer, Katharina; Razzazi-Fazeli, Ebrahim; Jungbauer, Alois

2017-02-01

The downstream processing of enveloped virus-like particles is very challenging because of the biophysical and structural similarity between correctly assembled particles and contaminating vesicular particles present in the feedstock. We used hydroxyl-functionalized polymethacrylate monoliths, providing hydrophobic and electrostatic binding contributions, for the purification of HIV-1 gag virus-like particles. The clarified culture supernatant was conditioned with ammonium sulfate and after membrane filtration loaded onto a 1 mL monolith. The binding capacity was 2 × 10 12 /mL monolith and was only limited by the pressure drop. By applying either a linear or a step gradient elution, to decrease the ammonium sulfate concentration, the majority of double-stranded DNA (88-90%) and host cell protein impurities (39-61%) could be removed while the particles could be separated into two fractions. Proteomic analysis and evaluation of the p24 concentration showed that one fraction contained majority of the HIV-1 gag and the other fraction was less contaminated with proteins originated from intracellular compartments. We were able to process up to 92 bed volumes of conditioned loading material within 3 h and eluted in average 7.3 × 10 11 particles per particle fraction, which is equivalent to 730 vaccination doses of 1 × 10 9 particles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Anti-listeria activity of poly(lactic acid)/sawdust particle biocomposite film impregnated with pediocin PA-1/AcH and its use in raw sliced pork.

PubMed

Woraprayote, Weerapong; Kingcha, Yutthana; Amonphanpokin, Pannawit; Kruenate, Jittiporn; Zendo, Takeshi; Sonomoto, Kenji; Benjakul, Soottawat; Visessanguan, Wonnop

2013-10-15

A novel poly(lactic acid) (PLA)/sawdust particle (SP) biocomposite film with anti-listeria activity was developed by incorporation of pediocin PA-1/AcH (Ped) using diffusion coating method. Sawdust particle played an important role in embedding pediocin into the hydrophobic PLA film. The anti-listeria activity of the PLA/SP biocomposite film incorporated with Ped (PLA/SP+Ped) was detected, while no activity against the tested pathogen was observed for the control PLA films (without SP and/or Ped). Dry-heat treatment of film before coating with Ped resulted in the highest Ped adsorption (11.63 ± 3.07 μg protein/cm(2)) and the highest anti-listeria activity. A model study of PLA/SP+Ped as a food-contact antimicrobial packaging on raw sliced pork suggests a potential inhibition of Listeria monocytogenes (99% of total listerial population) on raw sliced pork during the chilled storage. This study supports the feasibility of using PLA/SP+Ped film to reduce the initial load of L. monocytogenes on the surface of raw pork. © 2013.

In vitro wear assessment of the Charité Artificial Disc according to ASTM recommendations.

PubMed

Serhan, Hassan A; Dooris, Andrew P; Parsons, Matthew L; Ares, Paul J; Gabriel, Stefan M

2006-08-01

Biomechanical laboratory research. To evaluate the potential for Ultra High Molecular Weight Polyethylene (UHMWPE) wear debris from the Charité Artificial Disc. Cases of osteolysis from artificial discs are extremely rare, but hip and knee studies demonstrate the osteolytic potential and clinical concern of UHMWPE wear debris. Standards for testing artificial discs continue to evolve, and there are few detailed reports of artificial disc wear characterizations. Implant assemblies were tested to 10 million cycles of +/- 7.5 degrees flexion-extension or +/- 7.5 degrees left/right lateral bending, both with +/- 2 degrees axial rotation and 900 N to 1,850 N cyclic compression. Cores were weighed, measured, and photographed. Soak and loaded soak controls were used. Wear debris was analyzed via scanning electron microscopy and particle counters. The average total wear of the implants was 0.11 and 0.13 mg per million cycles, before and after accounting for serum absorption, respectively. Total height loss was approximately 0.2 mm. Wear debris ranged from submicron to > 10 microm in size. Under these test conditions, the Charité Artificial Disc produced minimal wear debris. Debris size and morphology tended to be similar to other CoCr-UHMWPE joints. More testing is necessary to evaluate the implants under a spectrum of loading conditions.

Quantitative investigation of physical factors contributing to gold nanoparticle-mediated proton dose enhancement.

PubMed

Cho, Jongmin; Gonzalez-Lepera, Carlos; Manohar, Nivedh; Kerr, Matthew; Krishnan, Sunil; Cho, Sang Hyun

2016-03-21

Some investigators have shown tumor cell killing enhancement in vitro and tumor regression in mice associated with the loading of gold nanoparticles (GNPs) before proton treatments. Several Monte Carlo (MC) investigations have also demonstrated GNP-mediated proton dose enhancement. However, further studies need to be done to quantify the individual physical factors that contribute to the dose enhancement or cell-kill enhancement (or radiosensitization). Thus, the current study investigated the contributions of particle-induced x-ray emission (PIXE), particle-induced gamma-ray emission (PIGE), Auger and secondary electrons, and activation products towards the total dose enhancement. Specifically, GNP-mediated dose enhancement was measured using strips of radiochromic film that were inserted into vials of cylindrical GNPs, i.e. gold nanorods (GNRs), dispersed in a saline solution (0.3 mg of GNRs/g or 0.03% of GNRs by weight), as well as vials containing water only, before proton irradiation. MC simulations were also performed with the tool for particle simulation code using the film measurement setup. Additionally, a high-purity germanium detector system was used to measure the photon spectrum originating from activation products created from the interaction of protons and spherical GNPs present in a saline solution (20 mg of GNPs/g or 2% of GNPs by weight). The dose enhancement due to PIXE/PIGE recorded on the films in the GNR-loaded saline solution was less than the experimental uncertainty of the film dosimetry (<2%). MC simulations showed highly localized dose enhancement (up to a factor 17) in the immediate vicinity (<100 nm) of GNRs, compared with hypothetical water nanorods (WNRs), mostly due to GNR-originated Auger/secondary electrons; however, the average dose enhancement over the entire GNR-loaded vial was found to be minimal (0.1%). The dose enhancement due to the activation products from GNPs was minimal (<0.1%) as well. In conclusion, under the currently investigated conditions that are considered clinically relevant, PIXE, PIGE, and activation products contribute minimally to GNP/GNR-mediated proton dose enhancement, whereas Auger/secondary electrons contribute significantly but only at short distances (<100 nm) from GNPs/GNRs.

Fast dissolution of poorly water soluble drugs from fluidized bed coated nanocomposites: Impact of carrier size.

PubMed

Azad, Mohammad; Moreno, Jacqueline; Bilgili, Ecevit; Davé, Rajesh

2016-11-20

Formation of core-shell nanocomposites of Fenofibrate and Itraconazole, model poorly water soluble drugs, via fluidized bed (FB) coating of their well-stabilized high drug loaded nanosuspensions is investigated. Specifically, the extent of dissolution enhancement, when fine carrier particles (sub-50μm) as opposed to the traditional large carrier particles (>300μm) are used, is examined. This allows testing the hypothesis that greatly increased carrier surface area and more importantly, thinner shell for finer carriers at the same drug loading can significantly increase the dissolution rate when spray-coated nanosuspensions are well-stabilized. Fine sub-50μm lactose (GranuLac ® 200) carrier particles were made fluidizable via dry coating with nano-silica, enabling decreased cohesion, fluidization and subsequent nanosuspension coating. For both drugs, 30% drug loaded suspensions were prepared via wet-stirred media milling using hydroxypropyl methyl cellulose and sodium dodecyl sulfate as stabilizers. The stabilizer concentrations were varied to affect the milled particle size and prepare a stable nanosuspension. The suspensions were FB coated onto hydrophilic nano-silica (M-5P) dry coated sub-50μm lactose (GranuLac ® 200) carrier particles or larger carrier particles of median size >300μm (PrismaLac ® 40). The resulting finer composite powders (sub-100μm) based on GranuLac ® 200 were freely flowing, had high bulk density, and had much faster, immediate dissolution of the poorly water-soluble drugs, in particular for Itraconazole. This is attributed to a much higher specific surface area of the carrier and corresponding thinner coating layer for fine carriers as opposed to those for large carrier particles. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of free-flowing peppermint essential oil-loaded hollow solid lipid micro- and nanoparticles via atomization with carbon dioxide.

PubMed

Yang, Junsi; Ciftci, Ozan Nazim

2016-09-01

The main objective of this study was to overcome the issues related to the volatility and strong smell that limit the efficient utilization of essential oils as "natural" antimicrobials in the food industry. Peppermint essential oil-loaded hollow solid lipid micro- and nanoparticles were successfully formed using a novel "green" method based on atomization of CO 2 -expanded lipid mixture. The highest essential oil loading efficiency (47.5%) was achieved at 50% initial essential oil concentration at 200bar expansion pressure and 50μm nozzle diameter, whereas there was no significant difference between the loading efficiencies (35%-39%) at 5%, 7%, 10%, and 20% initial essential oil concentrations (p>0.05). Particles generated at all initial essential oil concentrations were spherical but increasing the initial essential oil concentration to 20% and 50% generated a less smooth particle surface. After 4weeks of storage, 61.2%, 42.5%, 0.2%, and 2.0% of the loaded essential oil was released from the particles formed at 5%, 10%, 20%, and 50% initial essential oil concentrations, respectively. This innovative simple and clean process is able to form spherical hollow micro- and nanoparticles loaded with essential oil that can be used as food grade antimicrobials. These novel hollow solid lipid micro- and nanoparticles are alternatives to the solid lipid nanoparticles, and overcome the issues associated with the solid lipid nanoparticles. The dry free-flowing products make the handling and storage more convenient, and the simple and clean process makes the scaling up more feasible. Copyright © 2016 Elsevier Ltd. All rights reserved.

Settling velocity and preferential concentration of heavy particles under two-way coupling effects in homogeneous turbulence

NASA Astrophysics Data System (ADS)

Monchaux, R.; Dejoan, A.

2017-10-01

The settling velocity of inertial particles falling in homogeneous turbulence is investigated by making use of direct numerical simulation (DNS) at moderate Reynolds number that include momentum exchange between both phases (two-way coupling approach). Effects of particle volume fraction, particle inertia, and gravity are presented for flow and particle parameters similar to the experiments of Aliseda et al. [J. Fluid Mech. 468, 77 (2002), 10.1017/S0022112002001593]. A good agreement is obtained between the DNS and the experiments for the settling velocity statistics, when overall averaged, but as well when conditioned on the local particle concentration. Both DNS and experiments show that the settling velocity further increases with increasing volume fraction and local concentration. At the considered particle loading the effects of two-way coupling is negligible on the mean statistics of turbulence. Nevertheless, the DNS results show that fluid quantities are locally altered by the particles. In particular, the conditional average on the local particle concentration of the slip velocity shows that the main contribution to the settling enhancement results from the increase of the fluid velocity surrounding the particles along the gravitational direction induced by the collective particle back-reaction force. Particles and the surrounding fluid are observed to fall together, which in turn results in an amplification of the sampling of particles in the downward fluid motion. Effects of two-way coupling on preferential concentration are also reported. Increase of both volume fraction and gravity is shown to lower preferential concentration of small inertia particles while a reverse tendency is observed for large inertia particles. This behavior is found to be related to an attenuation of the centrifuge effects and to an increase of particle accumulation along gravity direction, as particle loading and gravity become large.

Buoyancy-corrected gravimetric analysis of lightly loaded filters.

PubMed

Rasmussen, Pat E; Gardner, H David; Niu, Jianjun

2010-09-01

Numerous sources of uncertainty are associated with the gravimetric analysis of lightly loaded air filter samples (< 100 microg). The purpose of the study presented here is to investigate the effectiveness and limitations of air buoyancy corrections over experimentally adjusted conditions of temperature (21-25 degrees C) and relative humidity (RH) (16-60% RH). Conditioning (24 hr) and weighing were performed inside the Archimedes M3 environmentally controlled chamber. The measurements were performed using 20 size-fractionated samples of resuspended house dust loaded onto Teflo (PTFE) filters using a Micro-Orifice Uniform Deposit Impactor representing a wide range of mass loading (7.2-3130 microg) and cut sizes (0.056-9.9 microm). By maintaining tight controls on humidity (within 0.5% RH of control setting) throughout pre- and postweighing at each stepwise increase in RH, it was possible to quantify error due to water absorption: 45% of the total mass change due to water absorption occurred between 16 and 50% RH, and 55% occurred between 50 and 60% RH. The buoyancy corrections ranged from -3.5 to +5.8 microg in magnitude and improved relative standard deviation (RSD) from 21.3% (uncorrected) to 5.6% (corrected) for a 7.2 microg sample. It is recommended that protocols for weighing low-mass particle samples (e.g., nanoparticle samples) should include buoyancy corrections and tight temperature/humidity controls. In some cases, conditioning times longer than 24 hr may be warranted.

Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung.

PubMed

Tewes, Frederic; Ehrhardt, Carsten; Healy, Anne Marie

2014-01-01

Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)-in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8±0.3μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8kJ/m(3). However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2±2.0μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH4)2CO3 and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2±0.8μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8±0.7% to 19.5±3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci. Copyright © 2013 Elsevier B.V. All rights reserved.

Aerosol Chemical Speciation Monitor (ACSM) Instrument Handbook

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, Thomas B.

The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) measures particle mass loading and chemical composition in real time for non-refractory sub-micron aerosol particles. The ACSM is designed for long-term unattended deployment and routine monitoring applications.

Improvements of the cyclone separator performance by down-comer tubes.

PubMed

Ganegama Bogodage, Sakura; Leung, A Y T

2016-07-05

Enhancement of fine particle (PM2.5) separation is important for cyclone separators to reduce any extra purification process required at the outlet. Therefore, the present experimental research was performed to explore the performance of cyclone separators modified with down-comer tubes at solid loading rates from 0 to 8.0 g/m(3) with a 10 m/s inlet velocity. The study proved the effectiveness of down-comer tubes in reducing the particle re-entrainment and increasing the finer separation with acceptable pressure drops, which was pronounced at low solid loading conditions. The experimental results were compared with theories of Smolik and Muschelknautz. Theories were acceptable for certain ranges, and theory breakdown was mainly due to the neglect of particle agglomeration, re-entrainment and the reduction of swirling energy, as well as the increase of wall friction due to presence of particles. Copyright © 2016. Published by Elsevier B.V.

Load management strategy for Particle-In-Cell simulations in high energy particle acceleration

NASA Astrophysics Data System (ADS)

Beck, A.; Frederiksen, J. T.; Dérouillat, J.

2016-09-01

In the wake of the intense effort made for the experimental CILEX project, numerical simulation campaigns have been carried out in order to finalize the design of the facility and to identify optimal laser and plasma parameters. These simulations bring, of course, important insight into the fundamental physics at play. As a by-product, they also characterize the quality of our theoretical and numerical models. In this paper, we compare the results given by different codes and point out algorithmic limitations both in terms of physical accuracy and computational performances. These limitations are illustrated in the context of electron laser wakefield acceleration (LWFA). The main limitation we identify in state-of-the-art Particle-In-Cell (PIC) codes is computational load imbalance. We propose an innovative algorithm to deal with this specific issue as well as milestones towards a modern, accurate high-performance PIC code for high energy particle acceleration.

Synthesis and Tribological Performance of Different Particle-Sized Nickel-Ion-Exchanged α-Zirconium Phosphates

NASA Astrophysics Data System (ADS)

Zhang, Xiaosheng; Xu, Hong; Dong, Jinxiang

2018-03-01

Nickel-ion-exchanged α-zirconium phosphate (Ni-α-ZrP) was synthesized by a mild hydrothermal synthesis method. Different raw material ratios (NaF/H3PO4/Ni(CH3COO)2·4H2O) influence the particle size of the Ni-α-ZrP samples. The grain size could be controlled and distributed from 20 to 600 nm. Ni-α-ZrP was evaluated as an additive in lithium grease in a four-ball test. A 3.0 wt.% addition of Ni-α-ZrP to lithium grease yielded maximum non-seizure load values of 1235 N, and the wear scar diameter on the lower balls is 0.42 mm at 294 N. Compared with smaller particles, the addition of Ni-α-ZrP with a larger particle size to grease yields a better load-carrying capacity.

Simulation of Particle Size Effect on Dynamic Properties and Fracture of PTFE-W-Al Composites

NASA Astrophysics Data System (ADS)

Herbold, Eric; Cai, Jing; Benson, David; Nesterenko, Vitali

2007-06-01

Recent investigations of the dynamic compressive strength of cold isostatically pressed (CIP) composites of polytetrafluoroethylene (PTFE), tungsten and aluminum powders show significant differences depending on the size of metallic particles. PTFE and aluminum mixtures are known to be energetic under dynamic and thermal loading. The addition of tungsten increases density and overall strength of the sample. Multi-material Eulerian and arbitrary Lagrangian-Eulerian methods were used for the investigation due to the complexity of the microstructure, relatively large deformations and the ability to handle the formation of free surfaces in a natural manner. The calculations indicate that the observed dependence of sample strength on particle size is due to the formation of force chains under dynamic loading in samples with small particle sizes even at larger porosity in comparison with samples with large grain size and larger density.

Mesoporous silica nanoparticle-based substrates for cell directed delivery of Notch signalling modulators to control myoblast differentiation

NASA Astrophysics Data System (ADS)

Böcking, Dominique; Wiltschka, Oliver; Niinimäki, Jenni; Shokry, Hussein; Brenner, Rolf; Lindén, Mika; Sahlgren, Cecilia

2014-01-01

Biochemical cues are critical to control stem cell function and can be utilized to develop smart biomaterials for stem cell engineering. The challenge is to deliver these cues in a restricted manner with spatial and temporal control. Here we have developed bilayer films of mesoporous silica nanoparticles for delayed cellular delivery of Notch modulators to promote muscle stem cell differentiation. We demonstrate that drug-loaded particles are internalized from the particle-covered surface, which allows for direct delivery of the drug into the cell and a delayed and confined drug release. Substrates of particles loaded with γ-secretase-inhibitors, which block the Notch signalling pathway, promoted efficient differentiation of myoblasts. The particle substrates were fully biocompatible and did not interfere with the inherent differentiation process. We further demonstrate that impregnating commercially available, biocompatible polymer scaffolds with MSNs allows for a free standing substrate for cell directed drug delivery.Biochemical cues are critical to control stem cell function and can be utilized to develop smart biomaterials for stem cell engineering. The challenge is to deliver these cues in a restricted manner with spatial and temporal control. Here we have developed bilayer films of mesoporous silica nanoparticles for delayed cellular delivery of Notch modulators to promote muscle stem cell differentiation. We demonstrate that drug-loaded particles are internalized from the particle-covered surface, which allows for direct delivery of the drug into the cell and a delayed and confined drug release. Substrates of particles loaded with γ-secretase-inhibitors, which block the Notch signalling pathway, promoted efficient differentiation of myoblasts. The particle substrates were fully biocompatible and did not interfere with the inherent differentiation process. We further demonstrate that impregnating commercially available, biocompatible polymer scaffolds with MSNs allows for a free standing substrate for cell directed drug delivery. Electronic supplementary information (ESI) available: (1) Particle characterization. (2) Immunohistochemistry and SEM analyses of C2C12 cells grown on films for 3, 6, 24 and 72 h. Light microscopy and WST1 analyses of cells grown on cover slips and films for 6, 24 and 72 h (3) Quantification of protein levels of C2C12 cells differentiating on cover slips versus MSN films. (4) Stability of MSN films in biological solution and the influence on cell viability. (5) Cell internalization of particles from MSN films and intracellular drug release at 12 and 24 h (6) Cell internalization and intracellular DiI release of MSNs from (3Dtro®) fiber scaffolds impregnated with MSNs. See DOI: 10.1039/c3nr04022d

Controlling chitosan-based encapsulation for protein and vaccine delivery

PubMed Central

Koppolu, Bhanu prasanth; Smith, Sean G.; Ravindranathan, Sruthi; Jayanthi, Srinivas; Kumar, Thallapuranam K.S.; Zaharoff, David A.

2014-01-01

Chitosan-based nano/microencapsulation is under increasing investigation for the delivery of drugs, biologics and vaccines. Despite widespread interest, the literature lacks a defined methodology to control chitosan particle size and drug/protein release kinetics. In this study, the effects of precipitation-coacervation formulation parameters on chitosan particle size, protein encapsulation efficiency and protein release were investigated. Chitosan particle sizes, which ranged from 300 nm to 3 μm, were influenced by chitosan concentration, chitosan molecular weight and addition rate of precipitant salt. The composition of precipitant salt played a significant role in particle formation with upper Hofmeister series salts containing strongly hydrated anions yielding particles with a low polydispersity index (PDI) while weaker anions resulted in aggregated particles with high PDIs. Sonication power had minimal effect on mean particle size, however, it significantly reduced polydispersity. Protein loading efficiencies in chitosan nano/microparticles, which ranged from 14.3% to 99.2%, was inversely related to the hydration strength of precipitant salts, protein molecular weight and directly related to the concentration and molecular weight of chitosan. Protein release rates increased with particle size and were generally inversely related to protein molecular weight. This study demonstrates that chitosan nano/microparticles with high protein loading efficiencies can be engineered with well-defined sizes and controllable release kinetics through manipulation of specific formulation parameters. PMID:24560459

A novel fractionation approach for water constituents - distribution of storm event metals.

PubMed

McKenzie, Erica R; Young, Thomas M

2013-05-01

A novel fractionation method, based on both particle size and settling characteristics, was employed to examine metal distributions among five fractions. In-stream and stormwater runoff samples were collected from four land use types: highway, urban, agricultural (storm event and irrigation), and natural. Highway samples contained the highest dissolved concentrations for most metals, and freshwater ambient water quality criteria were exceeded for Cd, Cu, Pb, and Zn in the first storm of the water year. Anthropogenic sources were indicated for Cu, Zn, Cd, and Pb in highway and urban samples, and total metal loadings (mg km(-2)) were observed to be as follows: highway > urban > agricultural storm event ∼ natural > agricultural irrigation. Notably, ∼10-fold higher suspended solids concentration was observed in the agricultural storm event sample, and suspended solids-associated metals were correspondingly elevated. Distribution coefficients revealed the following affinities: Zn, Ni, Cd, and Pb to large dense particles; and Cu, Zn, Cr, Ni, and Pb to colloidal organic matter.

A novel fractionation approach for water constituents – distribution of storm event metals

PubMed Central

McKenzie, Erica R.; Young, Thomas M.

2014-01-01

A novel fractionation method, based on both particle size and settling characteristics, was employed to examine metal distributions among five fractions. In-stream and stormwater runoff samples were collected from four land use types: highway, urban, agricultural (storm event and irrigation), and natural. Highway samples contained the highest dissolved concentrations for most metals, and freshwater ambient water quality criteria were exceeded for Cd, Cu, Pb, and Zn in the first storm of the water year. Anthropogenic sources were indicated for Cu, Zn, Cd, and Pb in highway and urban samples, and total metal loadings (mg/km2) were observed to be as follows: highway > urban > agricultural storm event ~ natural > agricultural irrigation. Notably, ~10-fold higher suspended solids concentration was observed in the agricultural storm event sample, and suspended solids-associated metals were correspondingly elevated. Distribution coefficients revealed the following affinities: Zn, Ni, Cd, and Pb to large dense particles; and Cu, Zn, Cr, Ni, and Pb to colloidal organic matter. PMID:23535891

Recent trends in ultra-fast HPLC: new generation superficially porous silica columns.

PubMed

Ali, Imran; Al-Othman, Zeid A; Nagae, Norikaju; Gaitonde, Vinay D; Dutta, Kamlesh K

2012-12-01

New generation columns, i.e. packed with superficially porous silica particles are available as trade names with following manufacturers: Halo, Ascentis Express, Proshell 120, Kinetex, Accucore, Sunshell, and Nucleoshell. These provide ultra-fast HPLC separations for a variety of compounds with moderate sample loading capacity and low back pressure. Chemistries of these columns are C(8), C(18), RP-Amide, hydrophilic interaction liquid chromatography, penta fluorophenyl (PFP), F5, and RP-aqua. Normally, the silica gel particles are of 2.7 and 1.7 μm as total and inner solid core diameters, respectively, with 0.5-μm-thick of outer porous layer having 90 Å pore sizes and 150 m(2)/g surface area. This article describes these new generation columns with special emphasis on their textures and chemistries, separations, optimization, and comparison (inter and intra stationary phases). Besides, future perspectives have also been discussed. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Micro-Encapsulated Porphyrins and Phthalocyanines - New Formulations in Photodynamic Therapy

NASA Astrophysics Data System (ADS)

Ion, R. M.

2017-06-01

Photodynamic therapy (PDT), as an innovative method for cancer tretament is based on a concerted action of some drugs, called sensitizers, which generate reactive oxygen species via a photochemical mechanism, leading to cellular necrosis or apoptosis. The present work aims at loading some sensitizers, as porphyrins (P) and phthalocyanines (Pc) into alginate particles. Particles were prepared by dropping alginate into an aqueous solution containing P or Pc and CaCl2, which allows the formation of particles through ionic crosslinking. It was obtained P or Pc loaded alginate beads with an average diameter of about 100 μm. For these systems, this paper analyses the spectroscopic properties, encapsulation into microcapsules, controlled releasing action and their photosensitizer capacity (singlet oxygen generation).

Premixed Flame Propagation in an Optically Thick Gas

NASA Technical Reports Server (NTRS)

Abbud-Madrid, Angel; Ronney, Paul D.

1993-01-01

Flame propagation in both the optically thin and the optically thick regime of radiative transport was studied experimentally using particle-laden gas mixtures. Data on flame shapes, propagation rates, peak pressure, maximum rate of pressure rise, and thermal decay in the burned gases are consistent with the hypothesis that, at low particle loadings, the particles act to increase the radiative loss from the gases, whereas at higher loadings, reabsorption of emitted radiation becomes significant. The reabsorption acts to decrease the net radiative loss and augment conductive heat transport. It is speculated that, in sufficiently large systems, in which the absorption length is much smaller than the system size, flammability limits might not exist at microgravity conditions because emitted radiation would not constitute a loss mechanism.

Structural equation model of total phosphorus loads in the Red River of the North Basin, USA and Canada

USGS Publications Warehouse

Ryberg, Karen R.

2017-01-01

Attribution of the causes of trends in nutrient loading is often limited to correlation, qualitative reasoning, or references to the work of others. This paper represents efforts to improve causal attribution of water-quality changes. The Red River of the North basin provides a regional test case because of international interest in the reduction of total phosphorus loads and the availability of long-term total phosphorus data and ancillary geospatial data with the potential to explain changes in water quality over time. The objectives of the study are to investigate structural equation modeling methods for application to water-quality problems and to test causal hypotheses related to the drivers of total phosphorus loads over the period 1970 to 2012. Multiple working hypotheses that explain total phosphorus loads and methods for estimating missing ancillary data were developed, and water-quality related challenges to structural equation modeling (including skewed data and scaling issues) were addressed. The model indicates that increased precipitation in season 1 (November–February) or season 2 (March–June) would increase total phosphorus loads in the basin. The effect of agricultural practices on total phosphorus loads was significant, although the effect is about one-third of the effect of season 1 precipitation. The structural equation model representing loads at six sites in the basin shows that climate and agricultural practices explain almost 60% of the annual total phosphorus load in the Red River of the North basin. The modeling process and the unexplained variance highlight the need for better ancillary long-term data for causal assessments.

Generation of bioaerosols during manual mail unpacking and sorting.

PubMed

Brandl, H; Bachofen, R; Bischoff, M

2005-01-01

The dynamics of bioaerosol generation in specific occupational environments where mail is manually unpacked and sorted was investigated. Total number of airborne particles was determined in four different size classes (0.3-0.5, 0.5-1, 1-5 and >5 microm) by laser particle counting. Time dependent formation of bioaerosols was monitored by culturing methods and by specific staining followed by flow cytometry. Besides handling of regular mail, specially prepared letters ('spiked letters') were added to the mailbags to deliberately release powdered materials from letters and to simulate high impact loads. These letters contained various dry powdered biological and nonbiological materials such as milk powder, mushrooms, herbs and cat litter. Regarding the four size classes, particulate aerosol composition before mail handling was determined as 83.2 +/- 1.0, 15.2 +/- 0.7, 1.7 +/- 0.4 and 0.04 +/- 0.02%, respectively, whereas the composition changed during sorting to 66.8 +/- 7.9, 22.3 +/- 3.6, 10.4 +/- 4.0 and 0.57 +/- 0.27%, respectively. Mail processing resulted in an increase in culturable airborne bacteria and fungi. Maximum concentrations of bacteria reached 450 CFU m(-3), whereas 270 CFU of fungi were detected. Indoor particle concentrations steadily increased during mail handling mostly associated with particles of diameters >1 microm. However, it was not possible to distinguish spiked letters from nonspiked by simple particle counting and CFU determinations. The dynamics of bioaerosol generation have to be addressed when monitoring specific occupational environments (such as mail sorting facilities) regarding the occurrence of biological particles.

Reduction of non-point source contaminants associated with road-deposited sediments by sweeping.

PubMed

Kim, Do-Gun; Kang, Hee-Man; Ko, Seok-Oh

2017-09-19

Road-deposited sediments (RDS) on an expressway, residual RDS collected after sweeping, and RDS removed by means of sweeping were analyzed to evaluate the degree to which sweeping removed various non-point source contaminants. The total RDS load was 393.1 ± 80.3 kg/km and the RDS, residual RDS, and swept RDS were all highly polluted with organics, nutrients, and metals. Among the metals studied, Cu, Zn, Pb, Ni, Ca, and Fe were significantly enriched, and most of the contaminants were associated with particles within the size range from 63 μm to 2 mm. Sweeping reduced RDS and its associated contaminants by 33.3-49.1% on average. We also measured the biological oxygen demand (BOD) of RDS in the present work, representing to our knowledge the first time that this has been done; we found that RDS contains a significant amount of biodegradable organics and that the reduction of BOD by sweeping was higher than that of other contaminants. Significant correlations were found between the contaminants measured, indicating that the organics and the metals originated from both exhaust and non-exhaust particles. Meanwhile, the concentrations of Cu and Ni were higher in 63 μm-2 mm particles than in smaller particles, suggesting that some metals in RDS likely exist intrinsically in particles, rather than only as adsorbates on particle surfaces. Overall, the results in this study showed that sweeping to collect RDS can be a good alternative for reduction of contaminants in runoff.

Estimated nitrogen loads from selected tributaries in Connecticut draining to Long Island Sound, 1999–2009

USGS Publications Warehouse

Mullaney, John R.; Schwarz, Gregory E.

2013-01-01

The total nitrogen load to Long Island Sound from Connecticut and contributing areas to the north was estimated for October 1998 to September 2009. Discrete measurements of total nitrogen concentrations and continuous flow data from 37 water-quality monitoring stations in the Long Island Sound watershed were used to compute total annual nitrogen yields and loads. Total annual computed yields and basin characteristics were used to develop a generalized-least squares regression model for use in estimating the total nitrogen yields from unmonitored areas in coastal and central Connecticut. Significant variables in the regression included the percentage of developed land, percentage of row crops, point-source nitrogen yields from wastewater-treatment facilities, and annual mean streamflow. Computed annual median total nitrogen yields at individual monitoring stations ranged from less than 2,000 pounds per square mile in mostly forested basins (typically less than 10 percent developed land) to more than 13,000 pounds per square mile in urban basins (greater than 40 percent developed) with wastewater-treatment facilities and in one agricultural basin. Medians of computed total annual nitrogen yields for water years 1999–2009 at most stations were similar to those previously computed for water years 1988–98. However, computed medians of annual yields at several stations, including the Naugatuck River, Quinnipiac River, and Hockanum River, were lower than during 1988–98. Nitrogen yields estimated for 26 unmonitored areas downstream from monitoring stations ranged from less than 2,000 pounds per square mile to 34,000 pounds per square mile. Computed annual total nitrogen loads at the farthest downstream monitoring stations were combined with the corresponding estimates for the downstream unmonitored areas for a combined estimate of the total nitrogen load from the entire study area. Resulting combined total nitrogen loads ranged from 38 to 68 million pounds per year during water years 1999–2009. Total annual loads from the monitored basins represent 63 to 74 percent of the total load. Computed annual nitrogen loads from four stations near the Massachusetts border with Connecticut represent 52 to 54 percent of the total nitrogen load during water years 2008–9, the only years with data for all the border sites. During the latter part of the 1999–2009 study period, total nitrogen loads to Long Island Sound from the study area appeared to increase slightly. The apparent increase in loads may be due to higher than normal streamflows, which consequently increased nonpoint nitrogen loads during the study, offsetting major reductions of nitrogen from wastewater-treatment facilities. Nitrogen loads from wastewater treatment facilities declined as much as 2.3 million pounds per year in areas of Connecticut upstream from the monitoring stations and as much as 5.8 million pounds per year in unmonitored areas downstream in coastal and central Connecticut.

Physicochemical properties and antioxidant activity of gamma-oryzanol-loaded liposome formulations for topical use.

PubMed

Viriyaroj, Amornrat; Ngawhirunpat, Tanasait; Sukma, Monrudee; Akkaramongkolporn, Prasert; Ruktanonchai, Uracha; Opanasopit, Praneet

2009-01-01

The objective of this study is to prepare the gamma-oryzanol-loaded liposomes and investigate their physicochemical properties and antioxidant activity intended for cosmetic applications. Liposomes, Composing phosphatidylCholine (PC) and Cholesterol (Chol), CHAPS or sodium taurocholate (NaTC) were prepared by sonication method. Gamma-oryzanol-loaded liposomes were prepared by using 3, 5 and 10% gamma-oryzanol as an initial concentration. The formulation factors in a particular type and composition of lipid and initial drug loading on the physicochemical properties (i.e., particle size, zeta potential, entrapment efficiency, drug release) and antioxidant activity were studied. The particle sizes of bare liposomes were in nanometer range. The gamma-oryzanol-loaded liposomes in formulations of PC/CHAPS and PC/NaTC liposomes were smaller than PC/Chol liposomes. The incorporation efficiency of 10% gamma-oryzanol-loaded PC/Chol liposomes was less than gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes allowing higher in vitro release rate due to higher free gamma-oryzanol in buffer solution. The antioxidant activity of gamma-oryzanol-loaded liposomes was not different from pure gamma-oryzanol. Both gamma-oryzanol-loaded PC/CHAPS liposomes and PC/NaTC liposomes were showed to enhance the antioxidant activity in NHF cells. gamma-oryzanol-loaded PC/Chol liposomes demonstrated the lowest cytotoxicity in NHF cells. It was conceivably concluded that liposomes prepared in this study are suitable for gamma-oryzanol incorporation without loss of antioxidant activity.

Coherent anti-Stokes Raman scattering microscopy driving the future of loaded mesoporous silica imaging.

PubMed

Fussell, Andrew L; Mah, Pei Ting; Offerhaus, Herman; Niemi, Sanna-Mari; Salonen, Jarno; Santos, Hélder A; Strachan, Clare

2014-11-01

This study reports the use of variants of coherent anti-Stokes Raman scattering (CARS) microscopy as a novel method for improved physicochemical characterization of drug-loaded silica particles. Ordered mesoporous silica is a biomaterial that can be loaded to carry a number of biochemicals, including poorly water-soluble drugs, by allowing the incorporation of drug into nanometer-sized pores. In this work, the loading of two poorly water-soluble model drugs, itraconazole and griseofulvin, in MCM-41 silica microparticles is characterized qualitatively, using the novel approach of CARS microscopy, which has advantages over other analytical approaches used to date and is non-destructive, rapid, label free, confocal and has chemical and physical specificity. The study investigated the effect of two solvent-based loading methods, namely immersion and rotary evaporation, and microparticle size on the three-dimensional (3-D) distribution of the two loaded drugs. Additionally, hyperspectral CARS microscopy was used to confirm the amorphous nature of the loaded drugs. Z-stacked CARS microscopy suggested that the drug, but not the loading method or particle size range, affected 3-D drug distribution. Hyperspectral CARS confirmed that the drug loaded in the MCM-41 silica microparticles was in an amorphous form. The results show that CARS microscopy and hyperspectral CARS microscopy can be used to provide further insights into the structural nature of loaded mesoporous silica microparticles as biomaterials. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of an indicator for characterizing particle size distribution and quality of stormwater runoff.

PubMed

Wang, Qian; Zhang, Qionghua; Dzakpasu, Mawuli; Lian, Bin; Wu, Yaketon; Wang, Xiaochang C

2018-03-01

Stormwater particles washed from road-deposited sediments (RDS) are traditionally characterized as either turbidity or total suspended solids (TSS). Although these parameters are influenced by particle sizes, neither of them characterizes the particle size distribution (PSD), which is of great importance in pollutant entrainment and treatment performance. Therefore, the ratio of turbidity to TSS (Tur/TSS) is proposed and validated as a potential surrogate for the bulk PSD and quality of stormwater runoff. The results show an increasing trend of Tur/TSS with finer sizes of both RDS and stormwater runoff. Taking heavy metals (HMs, including Cu, Pb, Zn, Cr, and Ni) as typical pollutants in stormwater runoff, the concentrations (mg/kg) were found to vary significantly during rainfall events and tended to increase significantly with Tur/TSS. Therefore, Tur/TSS is a valid parameter to characterize the PSD and quality of stormwater. The high negative correlations between Tur/TSS and rainfall intensity demonstrate that stormwater with higher Tur/TSS generates under low intensity and, thus, characterizes small volume, finer sizes, weak settleability, greater mobility, and bioavailability. Conversely, stormwater with lower Tur/TSS generates under high intensity and, thus, characterizes large volume, coarser sizes, good settleability, low mobility, and bioavailability. These results highlight the need to control stormwater with high Tur/TSS. Moreover, Tur/TSS can aid the selection of stormwater control measures with appropriate detention storage, pollution loading, and removal effectiveness of particles.

Measurement of Fine Particles From Mobile and Stationary Sources, and Reducing the Air Conditioner Power Consumption in Hybrid Electric Vehicles

NASA Astrophysics Data System (ADS)

Brewer, Eli Henry

We study the PM2.5and ultrafine exhaust emissions from a new natural gas-fired turbine power facility to better understand air pollution in California. To characterize the emissions from new natural gas turbines, a series of tests were performed on a GE LMS100 gas turbine. These tests included PM2.5 and wet chemical tests for SO2/SO 3 and NH3, as well as ultrafine (less than 100 nm in diameter) particulate matter measurements. The turbine exhaust had an average particle number concentration that was 2.3x103 times higher than ambient air. The majority of these particles were nanoparticles; at the 100 nm size, stack particle concentrations were about 20 times higher than ambient, and increased to 3.9x104 times higher on average in the 2.5 - 3 nm particle size range. This study also found that ammonia emissions were higher than expected, but in compliance with permit conditions. This was possibly due to an ammonia imbalance entering the catalyst, some flue gas bypassing the catalyst, or not enough catalyst volume. SO3 accounted for an average of 23% of the total sulfur oxides emissions measured. Some of the SO3 is formed in the combustion process, it is likely that the majority formed as the SO2 in the combustion products passed across the oxidizing CO catalyst and SCR catalyst. The 100 MW turbine sampled in this study emitted particle loadings similar to those previously measured from turbines in the SCAQMD area, however, the turbine exhaust contained far more particles than ambient air. The power consumed by an air conditioner accounts for a significant fraction of the total power used by hybrid and electric vehicles especially during summer. This study examined the effect of recirculation of cabin air on power consumption of mobile air conditioners both in-lab and on-road. Real time power consumption and vehicle mileage were recorded by an On Board Diagnostic monitor and carbon balance method. Vehicle mileage improved with increased cabin air recirculation. The recirculation of cabin air also significantly reduced in-cabin particle concentrations. Recirculation of cabin air is an excellent and immediate solution to increase vehicle mileage and improve cabin air quality.

Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

PubMed

Gonçalves, V S S; Matias, A A; Rodríguez-Rojo, S; Nogueira, I D; Duarte, C M M

2015-11-10

Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity. Copyright © 2015. Published by Elsevier B.V.

Roll-to-Roll Continuous Manufacturing Multifunctional Nanocomposites by Electric-Field-Assisted "Z" Direction Alignment of Graphite Flakes in Poly(dimethylsiloxane).

PubMed

Guo, Yuanhao; Chen, Yuwei; Wang, Enmin; Cakmak, Miko

2017-01-11

A roll-to-roll continuous process was developed to manufacture large-scale multifunctional poly(dimethylsiloxane) (PDMS) films embedded with thickness direction ("Z" direction) aligned graphite nanoparticles by application of electric field. The kinetics of particle "Z" alignment and chain formation was studied by tracking the real-time change of optical light transmission through film thickness direction. Benefiting from the anisotropic structure of aligned particle chains, the electrical and thermal properties of the nanocomposites were dramatically enhanced through the thickness direction as compared to those of the nanocomposites containing the same particle loading without electrical field alignment. With 5 vol % graphite loading, 250 times higher electrical conductivity, 43 times higher dielectric permittivity, and 1.5 times higher thermal conductivity was achieved in the film thickness direction after the particles were aligned under electrical field. Moreover, the aligned nanocomposites with merely 2 vol % graphite particles exhibit even higher electric conductivity and dielectric permittivity than those of the nonaligned nanocomposites at random percolation threshold (10 vol % particles), as the "electric-field-directed" percolation threshold concentration is substantially decreased using this process. As the graphite loading increases to 20 vol %, the aligned nanocomposites exhibit thermal conductivity as high as 6.05 W/m·K, which is 35 times the thermal conductivity of pure matrix. This roll-to-roll electric field continuous process provides a simple, low-cost, and commercially viable method to manufacture multifunctional nanocomposites for applications as embedded capacitor, electromagnetic (EM) shielding, and thermal interface materials.

Mucoadhesive microparticles for local treatment of gastrointestinal diseases.

PubMed

Preisig, Daniel; Roth, Roger; Tognola, Sandy; Varum, Felipe J O; Bravo, Roberto; Cetinkaya, Yalcin; Huwyler, Jörg; Puchkov, Maxim

2016-08-01

Mucoadhesive microparticles formulated in a capsule and delivered to the gastrointestinal tract might be useful for local drug delivery. However, swelling and agglomeration of hydrophilic polymers in the gastrointestinal milieu can have a negative influence on particle retention of mucoadhesive microparticles. In this work, we investigated the impact of dry-coating with nano-sized hydrophilic fumed silica on dispersibility and particle retention of mucoadhesive microparticles. As a model for local treatment of gastrointestinal diseases, antibiotic therapy of Clostridium difficile infections with metronidazole was selected. For particle preparation, we used a two-step fluidized-bed method based on drug loading of porous microcarriers and subsequent outer coating with the mucoadhesive polymer chitosan. The prepared microparticles were analysed for drug content, and further characterized by thermal analysis, X-ray diffraction, and scanning electron microscopy. The optimal molecular weight and content of chitosan were selected by measuring particle retention on porcine colonic mucosa under dynamic flow conditions. Mucoadhesive microparticles coated with 5% (weight of chitosan coating/total weight of particles) of low molecular weight chitosan showed good in vitro particle retention, and were used for the investigation of dispersibility enhancement. By increasing the amount of silica, the dissolution rate measured in the USPIV apparatus was increased, which was an indirect indication for improved dispersibility due to increased surface area. Importantly, mucoadhesion was not impaired up to a silica concentration of 5% (w/w). In summary, mucoadhesive microparticles with sustained-release characteristics over several hours were manufactured at pilot scale, and dry-coating with silica nanoparticles has shown to improve the dispersibility, which is essential for better particle distribution along the intestinal mucosa in humans. Therefore, this advanced drug delivery concept bears great potential, in particular for local treatment of gastrointestinal diseases. Copyright © 2016 Elsevier B.V. All rights reserved.

Lost but can't be neglected: Huge quantities of small microplastics hide in the South China Sea.

PubMed

Cai, Minggang; He, Haixia; Liu, Mengyang; Li, Siwei; Tang, Guowen; Wang, Weimin; Huang, Peng; Wei, Ge; Lin, Yan; Chen, Bin; Hu, Jiahui; Cen, Zhengnan

2018-08-15

Large quantities of microplastics with small particle sizes were found in the South China Sea (SCS). The abundances of microplastics in seawater were 0.045±0.093and 2569±1770particles/m 3 according to the bongo net and pumping sampling methods, respectively. Smaller-size fractions (size<0.3mm) contributed 92% of the number of microplastics to the total load. Continental slope is the largest reservoir of microplastics with an inventory of 295tons. 21 polymer types were found in the samples using the micro Fourier Transform Infrared Spectroscopy (FTIR), among which alkyds (22.5%) and polycaprolactone (PCL) (20.9%) accounted for almost half of the total polymer content. Lighter plastics would not only concentrate upon the coastal area, being more likely to drift further into open seas with ocean currents. The distribution characteristics showed that it was mainly controlled by terrestrial input of the Pearl River. This study, as the first report from SCS on microplastics in water for its distribution and influence factors, provided impetus for further research on the transportation fate and the behavior of this emerging pollutant from coastal zone to the open oceans. Copyright © 2018 Elsevier B.V. All rights reserved.

Porous Chromatographic Materials as Substrates for Preparing Synthetic Nuclear Explosion Debris Particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harvey, Scott D.; Liezers, Martin; Antolick, Kathryn C.

2013-06-13

In this study, we investigated several porous chromatographic materials as synthetic substrates for preparing surrogate nuclear explosion debris particles. The resulting synthetic debris materials are of interest for use in developing analytical methods. Eighteen metals, including some of forensic interest, were loaded onto materials by immersing them in metal solutions (556 mg/L of each metal) to fill the pores, applying gentle heat (110°C) to drive off water, and then treating them at high temperatures (up to 800°C) in air to form less soluble metal species. High-boiling-point metals were uniformly loaded on spherical controlled-pore glass to emulate early fallout, whereas low-boiling-pointmore » metals were loaded on core-shell silica to represent coated particles formed later in the nuclear fallout-formation process. Analytical studies were applied to characterize solubility, material balance, and formation of recalcitrant species. Dissolution experiments indicated loading was 1.5 to 3 times higher than expected from the pore volume alone, a result attributed to surface coating. Analysis of load solutions before and after filling the material pores revealed that most metals were passively loaded; that is, solutions filled the pores without active metal discrimination. However, niobium and tin concentrations were lower in solutions after pore filling, and were found in elevated concentrations in the final products, indicating some metals were selectively loaded. High-temperature treatments caused reduced solubility of several metal species, and loss of some metals (rhenium and tellurium) because volatile species were formed. Sample preparation reproducibility was high (the inter-batch relative standard deviation was 7.8%, and the intra-batch relative standard deviation was 0.84%) indicating that this material is suitable for use as a working standard for analytical methods development. We anticipate future standardized radionuclide-loaded materials will find use in radioanalytical methods development and/or serve as a starting material for the synthesis of more complex forms of nuclear explosion debris (e.g., Trinitite).« less

Analyzing the uncertainty of suspended sediment load prediction using sequential data assimilation

NASA Astrophysics Data System (ADS)

Leisenring, Marc; Moradkhani, Hamid

2012-10-01

SummaryA first step in understanding the impacts of sediment and controlling the sources of sediment is to quantify the mass loading. Since mass loading is the product of flow and concentration, the quantification of loads first requires the quantification of runoff volume. Using the National Weather Service's SNOW-17 and the Sacramento Soil Moisture Accounting (SAC-SMA) models, this study employed particle filter based Bayesian data assimilation methods to predict seasonal snow water equivalent (SWE) and runoff within a small watershed in the Lake Tahoe Basin located in California, USA. A procedure was developed to scale the variance multipliers (a.k.a hyperparameters) for model parameters and predictions based on the accuracy of the mean predictions relative to the ensemble spread. In addition, an online bias correction algorithm based on the lagged average bias was implemented to detect and correct for systematic bias in model forecasts prior to updating with the particle filter. Both of these methods significantly improved the performance of the particle filter without requiring excessively wide prediction bounds. The flow ensemble was linked to a non-linear regression model that was used to predict suspended sediment concentrations (SSCs) based on runoff rate and time of year. Runoff volumes and SSC were then combined to produce an ensemble of suspended sediment load estimates. Annual suspended sediment loads for the 5 years of simulation were finally computed along with 95% prediction intervals that account for uncertainty in both the SSC regression model and flow rate estimates. Understanding the uncertainty associated with annual suspended sediment load predictions is critical for making sound watershed management decisions aimed at maintaining the exceptional clarity of Lake Tahoe. The computational methods developed and applied in this research could assist with similar studies where it is important to quantify the predictive uncertainty of pollutant load estimates.

Fracture resistance and reliability of new zirconia posts.

PubMed

Oblak, Cedomir; Jevnikar, Peter; Kosmac, Tomaz; Funduk, Nenad; Marion, Ljubo

2004-04-01

The radicular portion of zirconia endodontic posts often need to be reshaped to achieve a definitive form and may be airborne-particle abraded to improve adhesion during luting. Therefore, the surface of the tetragonal zirconia ceramics may be transformed and damaged, influencing the mechanical properties of the material. This study compared the fracture resistance of prefabricated zirconia posts with a new retentive post-head after different surface treatments. Experimental zirconia posts of 2 different diameters, 1.3 mm and 1.5 mm, were produced from commercially available zirconia powder. A cylindro-conical outline form was used for the root portion of the system and a post-head with 3 retentive rings was designed. Sixty posts of each diameter were divided into 3 groups (n=20). Group 1 was ground with a coarse grit diamond bur; Group 2 was airborne-particle abraded with 110-microm fused alumina particles, and Group 3 was left as-received (controls). Posts were luted into the root-shaped artificial canals with the Clearfil adhesive system and Panavia 21 adhesive resin luting agent. The posts were loaded in a universal testing machine at an inclination of 45 degrees with the constant cross-head speed of 1 mm/min. The fracture load (N) necessary to cause post fracture was recorded, and the statistical significance of differences among groups was analyzed with 1-way ANOVA followed by the Fischer LSD test (alpha=.05). The variability was analyzed using Weibull statistics. Load to fracture values of all zirconia posts depended primarily on post diameter. Mean fracture loads (SD) in Newtons were 518.4 (+/-101.3), 993.6 (+/-224.1), and 622.7 (+/-110.3) for Groups 1 through 3, respectively, for thicker posts, and 385.9 (+/-110.3), 627.0 (+/-115.1), and 451.2 (+/-81.4) for Groups 1 through 3, respectively, for thinner posts. Airborne-particle-abraded posts exhibited significantly higher resistance to fracture (P<.05) than those in the other 2 groups for diameters 1.3 mm and 1.5 mm. Grinding reduced Weibull modulus compared with controls, and the values were 4.1 and 6.5 for thicker and thinner posts, respectively. Within the limitations of this study, the results suggest that grinding leads to a significant drop in load to fracture of zirconia posts, whereas airborne-particle abrasion increased the fracture load.

Stormwater quality processes for three land-use areas in Broward County, Florida

USGS Publications Warehouse

Mattraw, H.C.; Miller, Robert A.

1981-01-01

Systematic collection and chemical analysis of stormwater runoff samples from three small urban areas in Broward County, Florida, were obtained between 1974 and 1977. Thirty or more runoff-constituent loads were computed for each of the homogeneous land-use areas. The areas sampled were single family residential, highway, and a commercial shopping center. Rainfall , runoff, and nutrient and metal analyses were stored in a data-management system. The data-management system permitted computation of loads, publication of basic-data reports and the interface of environmental and load information with a comprehensive statistical analysis system. Seven regression models relating water quality loads to characteristics of peak discharge, antecedent conditions, season, storm duration and rainfall intensity were constructed for each of the three sites. Total water-quality loads were computed for the collection period by summing loads for individual storms. Loads for unsampled storms were estimated by using regression models and records of storm precipitation. Loadings, pounds per day per acre of hydraulically effective impervious area, were computed for the three land-use types. Total nitrogen, total phosphorus, and total residue loadings were highest in the residential area. Chemical oxygen demand and total lead loadings were highest in the commercial area. Loadings of atmospheric fallout on each watershed were estimated by bulk precipitation samples collected at the highway and commercial site. (USGS)

Characterization of suspended solids and total phosphorus loadings from small watersheds in Wisconsin

USGS Publications Warehouse

Danz, Mari E.; Corsi, Steven R.; Graczyk, David J.; Bannerman, Roger T.

2010-01-01

Knowledge of the daily, monthly, and yearly distribution of contaminant loadings and streamflow can be critical for the successful implementation and evaluation of water-quality management practices. Loading data for solids (suspended sediment and total suspended solids) and total phosphorus and streamflow data for 23 watersheds were summarized for four ecoregions of Wisconsin: the Driftless Area Ecoregion, the Northern Lakes and Forests Ecoregion, the North Central Hardwoods Ecoregion, and the Southeastern Wisconsin Till Plains Ecoregion. The Northern Lakes and Forests and the North Central Hardwoods Ecoregions were combined into one region for analysis due to a lack of sufficient data in each region. Urban watersheds, all located in the Southeastern Wisconsin Till Plains, were analyzed separately from rural watersheds as the Rural Southeastern Wisconsin Till Plains region and the Urban Southeastern Wisconsin Till Plains region. Results provide information on the distribution of loadings and streamflow between base flow and stormflow, the timing of loadings and streamflow throughout the year, and information regarding the number of days in which the majority of the annual loading is transported. The average contribution to annual solids loading from stormflow periods for the Driftless Area Ecoregion was 84 percent, the Northern Lakes and Forests/North Central Hardwoods region was 71 percent, the Rural Southeastern Wisconsin Till Plains region was 70 percent, and the Urban Southeastern Wisconsin Till Plains region was 90 percent. The average contributions to annual total phosphorus loading from stormflow periods were 72, 49, 61, and 76 percent for each of the respective regions. The average contributions to annual streamflow from stormflow periods are 20, 23, 31, and 50 percent for each of the respective regions. In all regions, the most substantial loading contributions for solids were in the late winter (February through March), spring (April through May), and early summer (June through July), with fall (October through November) and early winter (December through January) contributing the smallest loadings. The Northern Lakes and Forests/North Central Hardwoods region had some substantial loading in September. There was a similar pattern for total phosphorus loading in all regions, with the pattern somewhat less pronounced in urban watersheds. As with the loading results, average monthly streamflow values were greatest in late winter, spring, and early summer, with the lowest values typically in fall and early winter. Loading contributions were greater from stormflow than from base flow in all instances, except total phosphorus in the Northern Lakes and Forests/North Central Hardwoods region, which had equal or greater base-flow contribution for several months. Base flow constituted a greater percentage of the total streamflow than stormflow in all rural watersheds for all regions. Only a few storms each year dominated the annual loading totals for solids and total phosphorus. When daily loading values were ranked for the year, all regions reached 50 percent of the annual solids loading in the 5 highest loading days and nearly 50 percent of the annual total phosphorus loading in the 14 highest loading days.

Bioactive Polymeric Nanoparticles for Periodontal Therapy

PubMed Central

Alfonso-Rodríguez, Camilo Andrés; Medina-Castillo, Antonio L.; Alaminos, Miguel; Toledano, Manuel

2016-01-01

Aims to design calcium and zinc-loaded bioactive and cytocompatible nanoparticles for the treatment of periodontal disease. Methods PolymP-nActive nanoparticles were zinc or calcium loaded. Biomimetic calcium phosphate precipitation on polymeric particles was assessed after 7 days immersion in simulated body fluid, by scanning electron microscopy attached to an energy dispersive analysis system. Amorphous mineral deposition was probed by X-ray diffraction. Cell viability analysis was performed using oral mucosa fibroblasts by: 1) quantifying the liberated deoxyribonucleic acid from dead cells, 2) detecting the amount of lactate dehydrogenase enzyme released by cells with damaged membranes, and 3) by examining the cytoplasmic esterase function and cell membranes integrity with a fluorescence-based method using the Live/Dead commercial kit. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests. Results Precipitation of calcium and phosphate on the nanoparticles surfaces was observed in calcium-loaded nanoparticles. Non-loaded nanoparticles were found to be non-toxic in all the assays, calcium and zinc-loaded particles presented a dose dependent but very low cytotoxic effect. Conclusions The ability of calcium-loaded nanoparticles to promote precipitation of calcium phosphate deposits, together with their observed non-toxicity may offer new strategies for periodontal disease treatment. PMID:27820866

Development of γ-Oryzanol Rich Extract from Leum Pua Glutinous Rice Bran Loaded Nanostructured Lipid Carriers for Topical Delivery.

PubMed

Pornputtapitak, Warangkana; Pantakitcharoenkul, Jaturavit; Panpakdee, Ratchada; Teeranachaideekul, Veerawat; Sinchaipanid, Nuttanan

2018-02-01

Leum Pua is native Thai glutinous rice that contains antioxidants higher than white rice and other colored rice. One of the major antioxidants in rice brans is γ-oryzanol (GO). In this study, Leum Pua glutinous rice bran was extracted by different solvents. Oleic acid (~40 g/100 g extract), linoleic acid (~30 g/100 g extract), and palmitic acid (~20 g/100 g extract) were found to be major lipid components in the extracts. Methanol extract showed less variety of lipid components compared to the others. However, hexane extract showed the highest percent of γ-oryzanol compared to other solvents. Therefore, the hexane extract was selected to prepare nanostructured lipid carriers (NLC). The prepared NLC had small particles in the size range of 142.9 ± 0.4 nm for extract-loaded NLC and 137.1 ± 0.5 nm for GO-loaded NLC with narrow size distribution (PI < 0.1) in both formulations. The release profile of extract-loaded NLC formulation was slightly higher than GO-loaded NLC formulation. However, they did not follow the Higuchi model because of small amounts of γ-oryzanol loaded in NLC particles.

How much suspended particulate matter enters long-term in-channel storage?

NASA Astrophysics Data System (ADS)

Dietrich, Stephan; Kleisinger, Carmen; Kehl, Nora; Schubert, Birgit; Hillebrand, Gudrun

2017-04-01

The route of suspended particulate matter (SPM) downstream rivers strongly depends on discharge conditions and involves transport times and periods with resting times in deposits e.g. at areas with low-flow conditions near the channel bed. It is, however, difficult to estimate the contribution of SPM on the bed load. In this study, particle-bound polychlorinated biphenyls (PCB), which were released by an incident in the Elbe river (Central Europe) in spring 2015, could be used as unique tracer for transport pathways of SPM along the whole river stretch (over 700 km length), including low mountain ranges, lowlands, and the estuary. In 2015 the Elbe River was characterized by low-discharge conditions. Thus, the export of SPM on flood plains was strongly limited. The incident was monitored by concentration measurements of seven indicator PCB congeners along the inland part of the Elbe River as well as in the Elbe estuary. Data from ten monitoring stations (settling tanks) are considered. The total PCB load is calculated for all stations on the basis of monthly contaminant concentrations and daily suspended sediment concentrations. Monte-Carlo simulations assess the uncertainties of the calculated load. It is shown that the ratio of high versus low chlorinated PCB congeners is a suitable tracer to distinguish the PCB load of the incident from the long-term background signal (hereafter PCB6 ratio). We demonstrate that both the load of PCB as well as its chemical fingerprint allows the estimation of transport durations for the transport processes involved. Only a little part of the suspension has been transported via wash load. The PCB6 ratio is used to estimate mean transport velocities of the wash load fraction. A direct transport of wash load via the mean flow velocity of the water was not observed. Shortly after the incident, the PCB6 ratio was monitored 257 km downstream of the incident site in April 2015, in May first occurrence was monitored 514 km downstream of the incident site and in July it reaches the tidal weir 626 km downstream and enters the estuary. Here the transport velocity strongly decreases and the PCB6 ratio was not detected 25 km downstream the tidal weir before December 2015. The major part of the PCB-marked suspension is transported via suspended load. Interestingly, the reduction of total PCB tagged SPM load within the first 514 km downstream of the incident site indicates that roughly 75% of the annual SPM load (of the most upstream monitoring station located 43 km downstream of the incident site) is stored in the sediments of the Elbe River, suggesting that suspended sediment in transport enters storage after a relatively short distance. Once SPM settles, significant storage can occur over decadal time scales.

Drug Loading of Mesoporous Silicon

NASA Astrophysics Data System (ADS)

Moffitt, Anne; Coffer, Jeff; Wang, Mengjia

2011-03-01

The nanostructuring of crystalline solids with low aqueous solubilities by their incorporation into mesoporous host materials is one route to improve the bioavailability of such solids. Earlier studies suggest that mesoporous Si (PSi), with pore widths in the range of 5-50 nm, is a candidate for such an approach. In this presentation, we describe efforts to load curcumin into free-standing microparticles of PSi. Curcumin is a compound extracted from turmeric root, which is an ingredient of curry. Curucmin has shown activity against selected cancer cell lines, bacteria, and other medical conditions. However, curcumin has a very low bioavailability due to its extremely low water solubility (0.6 μ g/mL). Incorporation of curcumin was achieved by straightforward loading of the molten solid at 185circ; C. Loading experiments were performed using PSi particles of two different size ranges, 45-75 μ m and 150-250 μ m. Longer loading times and ratio of curcumin to PSi leads to a higher percentage of loaded curcumin in both PSi particle sizes (as determined by weight difference). The extent of curcumin crystallinity was assessed by x-ray diffraction (XRD). The solubility and release kinetics of loaded curcumin from the PSi was determined by extraction into water at 37circ; C, with analysis using UV-VIS spectrometry. NSF-REU and TCU.

Simulating tokamak PFC performance using simultaneous dual beam particle loading with pulsed heat loading

NASA Astrophysics Data System (ADS)

Sinclair, Gregory; Gonderman, Sean; Tripathi, Jitendra; Ray, Tyler; Hassanein, Ahmed

2017-10-01

The performance of plasma facing components (PFCs) in a fusion device are expected to change due to high flux particle loading during operation. Tungsten (W) is a promising PFC candidate material, due to its high melting point, high thermal conductivity, and low tritium retention. However, ion irradiation of D and He have each shown to diminish the thermal strength of W. This work investigates the synergistic effect between ion species, using dual beam irradiation, on the thermal response of W during ELM-like pulsed heat loading. Experiments studied three different loading conditions: laser, laser + He+, and laser + He+ + D+. 100 eV He+ and D+ exposures used a flux of 3.0-3.5 x 1020 m-2 s-1. ELM-like loading was applied using a pulsed Nd:YAG laser at an energy density of 0.38-1.51 MJ m-2 (3600 1 ms pulses at 1 Hz). SEM imaging revealed that laser + He+ loading at 0.76 MJ m-2 caused surface melting, inhibiting fuzz formation. Increasing the laser fluence decreased grain size and increased surface pore density. Thermally-enhanced migration of trapped gases appear to reflect resultant molten morphology. This work was supported by the National Science Foundation PIRE project.

Efficient production of nanoparticle-loaded orodispersible films by process integration in a stirred media mill.

PubMed

Steiner, Denise; Finke, Jan Henrik; Kwade, Arno

2016-09-25

Orodispersible films possess a great potential as a versatile platform for nanoparticle-loaded oral dosage forms. In this case, poorly water-soluble organic materials were ground in a stirred media mill and embedded into a polymer matrix. The aim of this study was the shortening of this manufacturing process by the integration of several process steps into a stirred media mill without facing disadvantages regarding the film quality. Furthermore, this process integration is time conserving due to the high stress intensities provided in the mill and applicable for high solids contents and high suspension viscosities. Two organic materials, the model compound Anthraquinone and the active pharmaceutical ingredient Naproxen were investigated in this study. Besides the impact of the film processing on the crystallinity of the particles in the orodispersible film, a particle load of up to 50% was investigated with the new developed processing route. Additionally, a disintegration test was developed, combining an appropriate amount of saliva substitute and a clear endpoint determination. In summary, high nanoparticle loads in orodispersible films with good particle size preservation after film redispersion in water as well as a manufacturing of the film casting mass within a few minutes in a stirred media mill was achieved. Copyright © 2016 Elsevier B.V. All rights reserved.

PM chemical composition and oxidative potential of the soluble fraction of particles at two sites in the urban area of Milan, Northern Italy

NASA Astrophysics Data System (ADS)

Perrone, Maria Grazia; Zhou, Jun; Malandrino, Mery; Sangiorgi, Giorgia; Rizzi, Cristiana; Ferrero, Luca; Dommen, Josef; Bolzacchini, Ezio

2016-03-01

Recent epidemiological evidence support the hypothesis that health effects from inhalation of air particles are governed by more than just particle mass, since specific chemical components have been identified as important contributors to mortality and hospitality admissions. We studied the chemical composition and the oxidative potential (OP) of total suspended particle (TSP) samples from Milan at two sites with different traffic loads: a site in the low emission zone (LEZ) and a traffic site (TR) outside. Two a-cellular assays; dithiothreitol (OPDTT) and 2‧,7' dichlorofluorescin (OPDCFH) were used to characterize the OP of the soluble fraction of particles. TSP samples from LEZ showed significantly lower concentrations of traffic-related chemical components compared to TR. The decrease in the concentrations from TR to LEZ was maximum for EC, with a LEZ/TR ratio of 0.64 (±0.18), and a significant reduction (p < 0.01) was also observed for PAHs (LEZ/TR = 0.73 ± 0.16), elements (Mn, Cu, Zn, Cd, Pb: LEZ/TR ranged between 0.64 and 0.82), OC (LEZ/TR = 0.85 ± 0.12) and NH4+ (LEZ/TR = 0.92 ± 0.07). OP measures, expressed as OP/m3 or OP/mg, were comparable between sites both for OPDTT and OPDCFH, thus not showing any significant impact of local traffic on OP values at sites. OPDTT and OPDCFH showed contrasting seasonal and daily trends, indicating that the two a-cellular assays gave complementary information on the OP of particles in Milan. The two OP assays resulted to be sensitive to different chemical properties of PM samples. OPDTT correlated positively only with Global Radiation (Spearman's rs = 0.38, p < 0.05), which could be considered as a proxy for high concentrations of secondary oxidizing organics, while OPDCFH was related to various PM chemical species, mainly correlated with total mass (rs = 0.65; p < 0.01), elements (e.g. Zn, rs = 0.67; As, rs = 0.65; p < 0.01) and the sum of sulfate and nitrate (rs = 0.63; p < 0.01), a proxy for secondary aerosol.

Limitations of subjective cognitive load measures in simulation-based procedural training.

PubMed

Naismith, Laura M; Cheung, Jeffrey J H; Ringsted, Charlotte; Cavalcanti, Rodrigo B

2015-08-01

The effective implementation of cognitive load theory (CLT) to optimise the instructional design of simulation-based training requires sensitive and reliable measures of cognitive load. This mixed-methods study assessed relationships between commonly used measures of total cognitive load and the extent to which these measures reflected participants' experiences of cognitive load in simulation-based procedural skills training. Two groups of medical residents (n = 38) completed three questionnaires after participating in simulation-based procedural skills training sessions: the Paas Cognitive Load Scale; the NASA Task Load Index (TLX), and a cognitive load component (CLC) questionnaire we developed to assess total cognitive load as the sum of intrinsic load (how complex the task is), extraneous load (how the task is presented) and germane load (how the learner processes the task for learning). We calculated Pearson's correlation coefficients to assess agreement among these instruments. Group interviews explored residents' perceptions about how the simulation sessions contributed to their total cognitive load. Interviews were audio-recorded, transcribed and subjected to qualitative content analysis. Total cognitive load scores differed significantly according to the instrument used to assess them. In particular, there was poor agreement between the Paas Scale and the TLX. Quantitative and qualitative findings supported intrinsic cognitive load as synonymous with mental effort (Paas Scale), mental demand (TLX) and task difficulty and complexity (CLC questionnaire). Additional qualitative themes relating to extraneous and germane cognitive loads were not reflected in any of the questionnaires. The Paas Scale, TLX and CLC questionnaire appear to be interchangeable as measures of intrinsic cognitive load, but not of total cognitive load. A more complete understanding of the sources of extraneous and germane cognitive loads in simulation-based training contexts is necessary to determine how best to measure and assess their effects on learning and performance outcomes. © 2015 John Wiley & Sons Ltd.

Monitoring to assess progress toward meeting the total maximum daily load for phosphorus in the Assabet River, Massachusetts: phosphorus loads, 2008 through 2010

USGS Publications Warehouse

Zimmerman, Marc J.; Savoie, Jennifer G.

2013-01-01

Wastewater discharges to the Assabet River contribute substantial amounts of phosphorus, which support accumulations of nuisance aquatic plants that are most evident in the river’s impounded reaches during the growing season. To restore the Assabet River’s water quality and aesthetics, the U.S. Environmental Protection Agency required the major wastewater-treatment plants in the drainage basin to reduce the amount of phosphorus discharged to the river by 2012. From October 2008 to December 2010, the U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection and in support of the requirements of the Total Maximum Daily Load for Phosphorus, collected weekly flow-proportional, composite samples for analysis of concentrations of total phosphorus and orthophosphorus upstream and downstream from each of the Assabet River’s two largest impoundments: Hudson and Ben Smith. The purpose of this monitoring effort was to evaluate conditions in the river before enhanced treatment-plant technologies had effected reductions in phosphorus loads, thereby defining baseline conditions for comparison with conditions following the mandated load reductions. The locations of sampling sites with respect to the impoundments enabled examination of the impoundments’ effects on phosphorus sequestration and on the transformation of phosphorus between particulate and dissolved forms. The study evaluated the differences between loads upstream and downstream from the impoundments throughout the sampling period and compared differences during two seasonal periods of relevance to aquatic plants: April 1 through October 31, the growing season, and November 1 through March 31, the nongrowing season, when existing permit limits allowed average monthly wastewater-treatment-plant-effluent concentrations of 0.75 milligram per liter (growing season) or 1.0 milligram per liter (nongrowing season) for total phosphorus. At the four sampling sites during the growing season, median weekly total phosphorus loads ranged from 110 to 190 kilograms (kg) and median weekly orthophosphorus loads ranged from 17 to 41 kg. During the nongrowing season, median weekly total phosphorus loads ranged from 240 to 280 kg and median weekly orthophosphorus loads ranged from 56 to 66 kg. During periods of low and moderate streamflow, estimated loads of total phosphorus upstream from the Hudson impoundment generally exceeded those downstream during the same sampling periods throughout the study; orthophosphorus loads downstream from the impoundment were typically larger than those upstream. When storm runoff substantially increased the streamflow, loads of total phosphorus and orthophosphorus both tended to be larger downstream than upstream. At the Ben Smith impoundment, both total phosphorus and orthophosphorus loads were generally larger downstream than upstream during low and moderate streamflow, but the differences were not as pronounced as they were at the Hudson impoundment. High flows were also associated with substantially larger total phosphorus and orthophosphorus loads downstream than those entering the impoundment from upstream. In comparing periods of growing- and nongrowing-season loads, the same patterns of loads entering and leaving were observed at both impoundments. That is, at the Hudson impoundment, total phosphorus loads entering the impoundment were greater than those leaving it, and orthophosphorus loads leaving the impoundment were greater than those entering it. At the Ben Smith impoundment, both total phosphorus and orthophosphorus loads leaving the impoundment were greater than those entering it. However, the loads were greater during the nongrowing seasons than during the growing seasons, and the net differences between upstream and downstream loads were about the same. The results indicate that some of the particulate fraction of the total phosphorus loads is sequestered in the Hudson impoundment, where particulate phosphorus probably undergoes some physical and biogeochemical transformations to the dissolved form orthophosphorus. The orthophosphorus may be taken up by aquatic plants or transported out of the impoundments. The results for the Ben Smith impoundment are less clear and suggest net export of total phosphorus and orthophosphorus. Differences between results from the two impoundments may be attributable in part to differences in their sizes, morphology, unmonitored tributaries, riparian land use, and processes within the impoundments that have not been quantified for this study.

Effects of highway runoff on streamflow and water quality in the Sevenmile Creek basin, a rural area in the Piedmont Province of North Carolina, July 1981 to July 1982

USGS Publications Warehouse

Harned, Douglas

1988-01-01

An evaluation of water-quality data from streams that receive stormwater runoff from a segment of Interstate Highway 85 in North Carolina indicated increased levels of many constituents compared to levels in nearby undeveloped basins. Additional data collected from a network of dry and wet atmospheric deposition collectors, lysimeter samples, soil surveys, wind measurements, and road sweepings helped define the general sources and migration of chemical substances near the highway. The eight study basins, located in a rural area in the Piedmont of North Carolina, had a combined area of 17.5 square miles and drained a 4.8-mile-long segment of the interstate. The average traffic flow along this section was 25,000 vehicles per day. During storm runoff, streamflow in basins traversed by the highway rose and fell more rapidly than that in the undeveloped basins. This more rapid response is due to the impervious, paved area of the basins and the manmade drainage systems designed to rapidly move water off the highway. Alkalinity, specific conductance, and concentrations of calcium, sodium, and chloride were greater at the highway stations than in the undeveloped basins as a result of highway salting for control of ice. Specific conductance and concentrations of dissolved and total nitrogen peaked at the beginning of each storm event. The data indicated that, for the study basins, highway runoff had little or no effect on suspended sediment, water temperature, dissolved oxygen, and pH. However, the pH at all stations decreased during stormflow because the rainfall drained off by the streams had pH values less than 5.7. High metals concentrations were found in the soils within 100 feet of the highway and in the soil water infiltrating the soil zone. Chromium, copper, nickel, and zinc concentrations in the streams near the highway generally were above the maximum levels recommended by the U.S. Environmental Protection Agency (EPA) for the protection of aquatic life. Lead and cadmium concentrations frequently exceeded the maximum levels recommended by the EPA for drinking water. The highway is a source of contaminants to surrounding areas. Particulate and metal loads in dustfall and chemical-constituent concentrations in soils decrease exponentially with distance from the highway. The highest concentrations of contaminants were found on the downwind side. Increased concentrations of metals (cadmium, chromium, iron, lead, nickel, and zinc) in rainfall were observed in samples collected near the highway and in samples collected approximately one-half mile away. Material loading due to dustfall was greater than loading due to rainfall. Loading due to saltated particles, those heavier particles bounced along the highway surface, was higher than loading due to dustfall. Saltation loads were greatest during the winter months because of highway deicing and sanding, which supplied an estimated two-thirds of the saltated materials. The remaining one-third of the saltated load came primarily from the deposition of particles from vehicles. Some of the greatest constituent concentrations were measured in the soil water sampled from the lysimeters located adjacent to the highway.

Statistical description of flume experiments on mixed-size bed-load transport and bed armoring processes

NASA Astrophysics Data System (ADS)

Chen, D.; Zhang, Y.

2008-12-01

The objective of this paper is to describe the statistical properties of experiments on non-uniform bed-load transport as well as the mechanism of bed armoring processes. Despite substantial effort made over the last two decades, the ability to compute the bed-load flux in a turbulent system remains poor. The major obstacles include the poor understanding of the formation of armor lays on bed surfaces. Such a layer is much flow-resistible than the underlying material and therefore significantly inhibits sediment transport from the reach. To study the problem, we conducted a flume study for mixed sand/gravel sediments. We observed that aggregated sediment blocks were the most common characters in armor layers - the largest sizes resist hydraulic forces, while the smaller sizes add interlocking support and prevent loss of fine material through gaps between the larger particles. Fractional transport rates with the existing of armor layers were measured with time by sediment trapping method at the end of flume. To address the intermittent and time-varying behavior of bed-load transport during bed armoring processes, we investigated the probability distribution of the fractional bed-load transport rates, and the underlying dynamic model derived from the continuous time random walk framework. Results indicate that it is critical to consider the impact of armor layers when a flow is sufficient to move some of the finer particles and yet insufficient to move all the larger particles on a channel bed.

Chemical characterization and in vitro toxicity of diesel exhaust particulate matter generated under varying conditions

PubMed Central

Cox, David P.; Drury, Bertram E.; Gould, Timothy R.; Kavanagh, Terrance J.; Paulsen, Michael H.; Sheppard, Lianne; Simpson, Christopher D.; Stewart, James A.; Larson, Timothy V.; Kaufman, Joel D.

2014-01-01

Epidemiologic studies have linked diesel exhaust (DE) to cardiovascular and respiratory morbidity and mortality, as well as lung cancer. DE composition is known to vary with many factors, although it is unclear how this influences toxicity. We generated eight DE atmospheres by applying a 2×2×2 factorial design and altering three parameters in a controlled exposure facility: (1) engine load (27 vs 82 %), (2) particle aging (residence time ~5 s vs ~5 min prior to particle collection), and (3) oxidation (with or without ozonation during dilution). Selected exposure concentrations of both diesel exhaust particles (DEPs) and DE gases, DEP oxidative reactivity via DTT activity, and in vitro DEP toxicity in murine endothelial cells were measured for each DE atmosphere. Cell toxicity was assessed via measurement of cell proliferation (colony formation assay), cell viability (MTT assay), and wound healing (scratch assay). Differences in DE composition were observed as a function of engine load. The mean 1-nitropyrene concentration was 15 times higher and oxidative reactivity was two times higher for low engine load versus high load. There were no substantial differences in measured toxicity among the three DE exposure parameters. These results indicate that alteration of applied engine load shifts the composition and can modify the biological reactivity of DE. While engine conditions did not affect the selected in vitro toxicity measures, the change in oxidative reactivity suggests that toxicological studies with DE need to take into account engine conditions in characterizing biological effects. PMID:26539254

AS1411 aptamer tagged PLGA-lecithin-PEG nanoparticles for tumor cell targeting and drug delivery.

PubMed

Aravind, Athulya; Jeyamohan, Prashanti; Nair, Remya; Veeranarayanan, Srivani; Nagaoka, Yutaka; Yoshida, Yasuhiko; Maekawa, Toru; Kumar, D Sakthi

2012-11-01

Liposomes and polymers are widely used drug carriers for controlled release since they offer many advantages like increased treatment effectiveness, reduced toxicity and are of biodegradable nature. In this work, anticancer drug-loaded PLGA-lecithin-PEG nanoparticles (NPs) were synthesized and were functionalized with AS1411 anti-nucleolin aptamers for site-specific targeting against tumor cells which over expresses nucleolin receptors. The particles were characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The drug-loading efficiency, encapsulation efficiency and in vitro drug release studies were conducted using UV spectroscopy. Cytotoxicity studies were carried out in two different cancer cell lines, MCF-7 and GI-1 cells and two different normal cells, L929 cells and HMEC cells. Confocal microscopy and flowcytometry confirmed the cellular uptake of particles and targeted drug delivery. The morphology analysis of the NPs proved that the particles were smooth and spherical in shape with a size ranging from 60 to 110 nm. Drug-loading studies indicated that under the same drug loading, the aptamer-targeted NPs show enhanced cancer killing effect compared to the corresponding non-targeted NPs. In addition, the PLGA-lecithin-PEG NPs exhibited high encapsulation efficiency and superior sustained drug release than the drug loaded in plain PLGA NPs. The results confirmed that AS1411 aptamer-PLGA-lecithin-PEG NPs are potential carrier candidates for differential targeted drug delivery. Copyright © 2012 Wiley Periodicals, Inc.

Position-Dependent Dynamics Explain Pore-Averaged Diffusion in Strongly Attractive Adsorptive Systems.

PubMed

Krekelberg, William P; Siderius, Daniel W; Shen, Vincent K; Truskett, Thomas M; Errington, Jeffrey R

2017-12-12

Using molecular simulations, we investigate the relationship between the pore-averaged and position-dependent self-diffusivity of a fluid adsorbed in a strongly attractive pore as a function of loading. Previous work (Krekelberg, W. P.; Siderius, D. W.; Shen, V. K.; Truskett, T. M.; Errington, J. R. Connection between thermodynamics and dynamics of simple fluids in highly attractive pores. Langmuir 2013, 29, 14527-14535, doi: 10.1021/la4037327) established that pore-averaged self-diffusivity in the multilayer adsorption regime, where the fluid exhibits a dense film at the pore surface and a lower density interior pore region, is nearly constant as a function of loading. Here we show that this puzzling behavior can be understood in terms of how loading affects the fraction of particles that reside in the film and interior pore regions as well as their distinct dynamics. Specifically, the insensitivity of pore-averaged diffusivity to loading arises from the approximate cancellation of two factors: an increase in the fraction of particles in the higher diffusivity interior pore region with loading and a corresponding decrease in the particle diffusivity in that region. We also find that the position-dependent self-diffusivities scale with the position-dependent density. We present a model for predicting the pore-average self-diffusivity based on the position-dependent self-diffusivity, which captures the unusual characteristics of pore-averaged self-diffusivity in strongly attractive pores over several orders of magnitude.

Nutrient loading to Lewisville Lake, north-central Texas, 1984-87

USGS Publications Warehouse

Gain, W.S.; Baldys, Stanley

1995-01-01

The estimated long-term (1974-89 water years) average annual total nitrogen load (excluding loads from sewage-treatment plants in ungaged areas) is 11,800 pounds per day. The estimated long-term (1974 89 water years) average annual total phosphorus load (excluding loads from sewage-treatment plants in ungaged areas) is 1,100 pounds per day.

Linking Load, Fuel, and Emission Controls to Photochemical Production of Secondary Organic Aerosol from a Diesel Engine.

PubMed

Jathar, Shantanu H; Friedman, Beth; Galang, Abril A; Link, Michael F; Brophy, Patrick; Volckens, John; Eluri, Sailaja; Farmer, Delphine K

2017-02-07

Diesel engines are important sources of fine particle pollution in urban environments, but their contribution to the atmospheric formation of secondary organic aerosol (SOA) is not well constrained. We investigated direct emissions of primary organic aerosol (POA) and photochemical production of SOA from a diesel engine using an oxidation flow reactor (OFR). In less than a day of simulated atmospheric aging, SOA production exceeded POA emissions by an order of magnitude or more. Efficient combustion at higher engine loads coupled to the removal of SOA precursors and particle emissions by aftertreatment systems reduced POA emission factors by an order of magnitude and SOA production factors by factors of 2-10. The only exception was that the retrofitted aftertreatment did not reduce SOA production at idle loads where exhaust temperatures were low enough to limit removal of SOA precursors in the oxidation catalyst. Use of biodiesel resulted in nearly identical POA and SOA compared to diesel. The effective SOA yield of diesel exhaust was similar to that of unburned diesel fuel. While OFRs can help study the multiday evolution, at low particle concentrations OFRs may not allow for complete gas/particle partitioning and bias the potential of precursors to form SOA.

Effect of amine functionalization of spherical MCM-41 and SBA-15 on controlled drug release

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szegedi, A., E-mail: szegedi@chemres.h; Popova, M.; Goshev, I.

2011-05-15

MCM-41 and SBA-15 silica materials with spherical morphology and different particle sizes were synthesized and modified by post-synthesis method with 3-aminopropyltriethoxysilane (APTES). A comparative study of the adsorption and release of a model drug, ibuprofen, were carried out. The modified and drug loaded mesoporous materials were characterized by XRD, TEM, N{sub 2} physisorption, thermal analysis, elemental analysis and FT-IR spectroscopy. Surface modification with amino groups resulted in high degree of ibuprofen loading and slow rate of release for MCM-41, whereas it was the opposite for SBA-15. The adsorbed drug content and the delivery rate can be predetermined by the choicemore » of mesoporous material with the appropriate structural characteristics and surface functionality. -- Graphical Abstract: Ibuprofen delivery from the parent and amino-modified spherical MCM-41 materials with 100 nm (small) and 500 nm (large) particle sizes. Display Omitted Highlights: {yields} Spherical type MCM-41 and SBA-15 with different particle sizes were modified by APTES. {yields} Adsorption and release rate of ibuprofen were compared. {yields} High degree of ibuprofen loading, slow release rate for MCM-41, the opposite for SBA-15. {yields} MCM-41 with 100 nm particles was more stable and showed slower release rate« less

Nitrogen loads from selected rivers in the Long Island Sound Basin, 2005–13, Connecticut and Massachusetts

USGS Publications Warehouse

Mullaney, John R.

2016-03-29

Total nitrogen loads at 14 water-quality monitoring stations were calculated by using discrete measurements of total nitrogen and continuous streamflow data for the period 2005–13 (water years 2006–13). Total nitrogen loads were calculated by using the LOADEST computer program.Overall, for water years 2006–13, streamflow in Connecticut was generally above normal. Total nitrogen yields ranged from 1,160 to 23,330 pounds per square mile per year. Total nitrogen loads from the French River at North Grosvenordale and the Still River at Brookfield Center, Connecticut, declined noticeably during the study period. An analysis of the bias in estimated loads indicated unbiased results at all but one station, indicating generally good fit for the LOADEST models.

Concentrations, loads, and yields of total phosphorus, total nitrogen, and suspended sediment and bacteria concentrations in the Wister Lake Basin, Oklahoma and Arkansas, 2011-13

USGS Publications Warehouse

Buck, Stephanie D.

2014-01-01

The Poteau Valley Improvement Authority uses Wister Lake in southeastern Oklahoma as a public water supply. Total phosphorus, total nitrogen, and suspended sediments from agricultural runoff and discharges from wastewater treatment plants and other sources have degraded water quality in the lake. As lake-water quality has degraded, water-treatment cost, chemical usage, and sludge production have increased for the Poteau Valley Improvement Authority. The U.S. Geological Survey (USGS), in cooperation with the Poteau Valley Improvement Authority, investigated and summarized concentrations of total phosphorus, total nitrogen, suspended sediment, and bacteria (Escherichia coli and Enterococcus sp.) in surface water flowing to Wister Lake. Estimates of total phosphorus, total nitrogen, and suspended sediment loads, yields, and flow-weighted mean concentrations of total phosphorus and total nitrogen concentrations were made for the Wister Lake Basin for a 3-year period from October 2010 through September 2013. Data from water samples collected at fixed time increments during base-flow conditions and during runoff conditions at the Poteau River at Loving, Okla. (USGS station 07247015), the Poteau River near Heavener, Okla. (USGS station 07247350), and the Fourche Maline near Leflore, Okla. (USGS station 07247650), water-quality stations were used to evaluate water quality over the range of streamflows in the basin. These data also were collected to estimate annual constituent loads and yields by using regression models. At the Poteau River stations, total phosphorus, total nitrogen, and suspended sediment concentrations in surface-water samples were significantly larger in samples collected during runoff conditions than in samples collected during base-flow conditions. At the Fourche Maline station, in contrast, concentrations of these constituents in water samples collected during runoff conditions were not significantly larger than concentrations during base-flow conditions. Flow-weighted mean total phosphorus concentrations at all three stations from 2011 to 2013 were several times larger than the Oklahoma State Standard for Scenic Rivers (0.037 milligrams per liter [mg/L]), with the largest flow-weighted phosphorus concentrations typically being measured at the Poteau River at Loving, Okla., station. Flow-weighted mean total nitrogen concentrations did not vary substantially between the Poteau River stations and the Fourche Maline near Leflore, Okla., station. At all of the sampled water-quality stations, bacteria (Escherichia coli and Enterococcus sp.) concentrations were substantially larger in water samples collected during runoff conditions than in water samples collected during base-flow conditions from 2011 to 2013. Estimated annual loads of total phosphorus, total nitrogen, and suspended sediment in the Poteau River stations during runoff conditions ranged from 82 to 98 percent of the total annual loads of those constituents. Estimated annual loads of total phosphorus, total nitrogen, and suspended sediment in the Fourche Maline during runoff conditions ranged from 86 to nearly 100 percent of the total annual loads. Estimated seasonal total phosphorus loads generally were smallest during base-flow and runoff conditions in autumn. Estimated seasonal total phosphorus loads during base-flow conditions tended to be largest in winter and during runoff conditions tended to be largest in the spring. Estimated seasonal total nitrogen loads tended to be smallest in autumn during base-flow and runoff conditions and largest in winter during runoff conditions. Estimated seasonal suspended sediment loads tended to be smallest during base-flow conditions in the summer and smallest during runoff conditions in the autumn. The largest estimated seasonal suspended sediment loads during runoff conditions typically were in the spring. The estimated mean annual total phosphorus yield was largest at the Poteau River at Loving, Okla., water-quality station. The estimated mean annual total phosphorus yield was largest during base flow at the Poteau River at Loving, Okla., water-quality station and at both of the Poteau River water-quality stations during runoff conditions. The estimated mean annual total nitrogen yields were largest at the Poteau River water-quality stations. Estimated mean annual total nitrogen yields were largest during base-flow and runoff conditions at the Poteau River at Loving, Okla., water-quality station. The estimated mean annual suspended sediment yield was largest at the Poteau River near Heavener, Okla., water-quality station during base-flow and runoff conditions. Flow-weighted mean concentrations indicated that total phosphorus inputs from the Poteau River Basin in the Wister Lake Basin were larger than from the Fourche Maline Basin. Flow-weighted mean concentrations of total nitrogen did not vary spatially in a consistent manner. The Poteau River and the Fourche Maline contributed estimated annual total phosphorus loads of 137 to 278 tons per year (tons/yr) to Wister Lake. Between 89 and 95 percent of the annual total phosphorus loads were transported to Wister Lake during runoff conditions. The Poteau River and the Fourche Maline contributed estimated annual total nitrogen loads of 657 to 1,294 tons/yr, with 86 to 94 percent of the annual total nitrogen loads being transported to Wister Lake during runoff conditions. The Poteau River and the Fourche Maline contributed estimated annual total suspended sediment loads of 110,919 to 234,637 tons/yr, with 94 to 99 percent of the annual suspended sediment loads being transported to Wister Lake during runoff conditions. Most of the total phosphorus and suspended sediment were delivered to Wister Lake during runoff conditions in the spring. The majority of the total nitrogen was delivered to Wister Lake during runoff conditions in winter.

Immunogenicity of diphtheria toxoid and poly(I:C) loaded cationic liposomes after hollow microneedle-mediated intradermal injection in mice.

PubMed

Du, Guangsheng; Leone, Mara; Romeijn, Stefan; Kersten, Gideon; Jiskoot, Wim; Bouwstra, Joke A

2018-06-02

In this study, we aimed to investigate the immunogenicity of cationic liposomes loaded with diphtheria toxoid (DT) and poly(I:C) after hollow microneedle-mediated intradermal vaccination in mice. The following liposomal formulations were studied: DT loaded liposomes, a mixture of free DT and poly(I:C)-loaded liposomes, a mixture of DT-loaded liposomes and free poly(I:C), and liposomal formulations with DT and poly(I:C) either individually or co-encapsulated in the liposomes. Reference groups were DT solution adjuvanted with or without poly(I:C) (DT/poly(I:C)). The liposomal formulations were characterized in terms of particle size, zeta potential, loading and release of DT and poly(I:C). After intradermal injection of BALB/c mice with the formulations through a hollow microneedle, the immunogenicity was assessed by DT-specific ELISAs. All formulations induced similar total IgG and IgG1 titers. However, all the liposomal groups containing both DT and poly(I:C) showed enhanced IgG2a titers compared to DT/poly(I:C) solution, indicating that the immune response was skewed towards a Th1 direction. This enhancement was similar for all liposomal groups that contain both DT and poly(I:C) in the formulations. Our results reveal that a mixture of DT encapsulated liposomes and poly(I:C) encapsulated liposomes have a similar effect on the antibody responses as DT and poly(I:C) co-encapsulated liposomes. These findings may have implications for future design of liposomal vaccine delivery systems. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

The permeability of puerarin loaded poly(butylcyanoacrylate) nanoparticles coated with polysorbate 80 on the blood-brain barrier and its protective effect against cerebral ischemia/reperfusion injury.

PubMed

Zhao, Li-xia; Liu, An-chang; Yu, Shu-wen; Wang, Zeng-xin; Lin, Xiao-qian; Zhai, Guang-xi; Zhang, Qing-zhu

2013-01-01

Puerarin (PUE) is a good candidate for treating stroke, but its low concentration in brain after administration limits its curative efficacy. The aim of the present work was to design and characterize PUE loaded poly(butylcyanoacrylate) nanoparticles (PBCN) coated with polysorbate 80 (Ps 80), and to evaluate the effect of PBCN on the permeability of PUE across the blood-brain barrier (BBB) and the effect of PUE loaded PBCN on the cerebral ischemia/reperfusion injury. PUE loaded PBCN were successfully prepared by anionic polymerization method with the mean particle size of 201.2 nm and the zeta potential of -7.72 mV. The in vitro release behavior of PUE from the nanoparticles showed a biphasic profile manner with an initial burst release followed by a sustained release. The results of pharmacokinetic and biodistribution to brain performed in mice after intravenous administration showed that the drug concentrations in blood and brain for PUE loaded PBCN were both greater than these for the free drug. Moreover, compared with free drug, the vein injection of PUE loaded PBCN exerted the better neuroprotective effect in rats with focal cerebral ischemic injury via significantly decreasing neurological deficit scores, increasing body weight, lowing brain water content, and reducing the infarct volume. The results indicated that this preparation may reduce the total dose required for the stroke therapy with concurrent reduction in dose related toxicity. All these findings suggest that PBCN could enhance the transport of PUE to brain and have a potential as a neuroprotective agent in the focal cerebral ischemic injury.

Modeling of Stick-Slip Behavior in Sheared Granular Fault Gouge Using the Combined Finite-Discrete Element Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Ke; Euser, Bryan J.; Rougier, Esteban

Sheared granular layers undergoing stick-slip behavior are broadly employed to study the physics and dynamics of earthquakes. In this paper, a two-dimensional implementation of the combined finite-discrete element method (FDEM), which merges the finite element method (FEM) and the discrete element method (DEM), is used to explicitly simulate a sheared granular fault system including both gouge and plate, and to investigate the influence of different normal loads on seismic moment, macroscopic friction coefficient, kinetic energy, gouge layer thickness, and recurrence time between slips. In the FDEM model, the deformation of plates and particles is simulated using the FEM formulation whilemore » particle-particle and particle-plate interactions are modeled using DEM-derived techniques. The simulated seismic moment distributions are generally consistent with those obtained from the laboratory experiments. In addition, the simulation results demonstrate that with increasing normal load, (i) the kinetic energy of the granular fault system increases; (ii) the gouge layer thickness shows a decreasing trend; and (iii) the macroscopic friction coefficient does not experience much change. Analyses of the slip events reveal that, as the normal load increases, more slip events with large kinetic energy release and longer recurrence time occur, and the magnitude of gouge layer thickness decrease also tends to be larger; while the macroscopic friction coefficient drop decreases. Finally, the simulations not only reveal the influence of normal loads on the dynamics of sheared granular fault gouge, but also demonstrate the capabilities of FDEM for studying stick-slip dynamic behavior of granular fault systems.« less

Modeling of Stick-Slip Behavior in Sheared Granular Fault Gouge Using the Combined Finite-Discrete Element Method

DOE PAGES

Gao, Ke; Euser, Bryan J.; Rougier, Esteban; ...

2018-06-20

Sheared granular layers undergoing stick-slip behavior are broadly employed to study the physics and dynamics of earthquakes. In this paper, a two-dimensional implementation of the combined finite-discrete element method (FDEM), which merges the finite element method (FEM) and the discrete element method (DEM), is used to explicitly simulate a sheared granular fault system including both gouge and plate, and to investigate the influence of different normal loads on seismic moment, macroscopic friction coefficient, kinetic energy, gouge layer thickness, and recurrence time between slips. In the FDEM model, the deformation of plates and particles is simulated using the FEM formulation whilemore » particle-particle and particle-plate interactions are modeled using DEM-derived techniques. The simulated seismic moment distributions are generally consistent with those obtained from the laboratory experiments. In addition, the simulation results demonstrate that with increasing normal load, (i) the kinetic energy of the granular fault system increases; (ii) the gouge layer thickness shows a decreasing trend; and (iii) the macroscopic friction coefficient does not experience much change. Analyses of the slip events reveal that, as the normal load increases, more slip events with large kinetic energy release and longer recurrence time occur, and the magnitude of gouge layer thickness decrease also tends to be larger; while the macroscopic friction coefficient drop decreases. Finally, the simulations not only reveal the influence of normal loads on the dynamics of sheared granular fault gouge, but also demonstrate the capabilities of FDEM for studying stick-slip dynamic behavior of granular fault systems.« less

Aerosol properties over the western Mediterranean Basin: temporal and spatial variability

NASA Astrophysics Data System (ADS)

Lyamani, H.; Valenzuela, A.; Perez-Ramirez, D.; Toledano, C.; Granados-Muñoz, M. J.; Olmo, F. J.; Alados-Arboledas, L.

2014-08-01

This study focuses on the analysis of AERONET aerosol data obtained over Alborán Island (35.95° N, 3.01° W, 15 m a.s.l.) in the western Mediterranean from July 2011 to January 2012. Additional aerosol data from three nearest AERONET stations and the Maritime Aerosol Network (MAN) were also analyzed in order to investigate the aerosol temporal and spatial variations over this scarcely explored region. Aerosol load over Alborán was significantly larger than that reported for open oceanic areas not affected by long-range transport. High aerosol loads over Alborán were mainly associated with desert dust transport from North Africa and occasional advection of anthropogenic fine particles from Italy. The fine particle load observed over Alborán was surprisingly similar to that obtained over the other three nearest AERONET stations in spite of the large differences in local aerosol sources. The results from MAN acquired over the Mediterranean Sea, Black Sea and Atlantic Ocean from July to November 2011 revealed a pronounced predominance of fine particles during the cruise period. Alborán was significantly less influenced by anthropogenic particles than the Black Sea and central and eastern Mediterranean regions during the cruise period. Finally, the longer AERONET dataset from Málaga (36.71° N, 4.4° W, 40 m a.s.l.), port city in southern Spain, shows that no significant changes in columnar aerosol loads since the European Directive on ship emissions was implemented in 2010 were observed over this site.