Influence of the Southeast Asian biomass burnings on the atmospheric persistent organic pollutants observed at near sources and receptor site

NASA Astrophysics Data System (ADS)

Chang, Shun-Shiang; Lee, Wen-Jhy; Wang, Lin-Chi; Lin, Neng-Huei; Chang-Chien, Guo-Ping

2013-10-01

Persistent organic pollutants (POPs) such as PCDD/Fs, PCBs, PBDD/Fs, PBBs and PBDEs are bio-accumulative, toxic, and susceptible to long-range transport (LRT). This study is the first that comprehensively discusses the long-range atmospheric transport behavior of these five groups of POPs. The main goal is to investigate the atmospheric characteristics of these POPs at the biomass burning sites of Chiang Mai in Thailand, and Da Nang in Vietnam, as well as the influence of the Southeast Asian biomass burnings on the Lulin Atmospheric Background Station (LABS) in Taiwan. Biomass burning in Southeast Asia is usually carried to remove the residues of agricultural activities. The ambient air in Da Nang seems to be more seriously affected by the local biomass burnings than that in Chiang Mai. The elevated atmospheric brominated POP (PBDD/Fs, PBBs and PBDEs) concentrations in Da Nang were attributed to the biomass burning and viewed as mostly unrelated to the local use of brominated flame retardants. In the spring of 2010, the mean atmospheric concentrations in LABS during the first and second Intensive Observation Periods (IOPs) were 0.00428 and 0.00232 pg I-TEQ Nm-3 for PCDD/Fs, 0.000311 and 0.000282 pg WHO-TEQ m-3 for PCBs, 0.000379 and 0.000449 pg TEQ Nm-3 for total PBDD/Fs, 0.0208 and 0.0163 pg Nm-3 for total PBBs, and 109 and 18.2 pg Nm-3 for total PBDEs, respectively. These values represent the above concentrations due to the Southeast Asian biomass burnings. The affected atmospheric POP concentrations at the LABS were still at least one order lower than those in other atmospheric environments, except for the PBDE concentrations during the first IOP (109 pg Nm-3), which was surprisingly higher than those in Taiwanese metal complex areas (93.9 pg Nm-3) and urban areas (34.7 pg Nm-3). Atmospheric POP concentrations do not seem to dramatically decrease during long-range transport, and the reasons for this need to be further investigated.

[Worker exposure to ultrafine particles during carbon black treatment].

PubMed

Mikołajczyk, Urszula; Bujak-Pietrek, Stella; Szadkowska-Stańczyk, Irena

2015-01-01

The aim of the project was to assess the exposure of workers to ultrafine particles released during handling and packing of carbon black. The assessment included the results of the measurements performed in a carbon black handling plant before, during, and after work shift. The number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was assayed by a condensation particle counter (CPC). The mass concentration of particles was determined by a DustTrak II DRX aerosol concentration monitor. The surface area concentration of the particles potentially deposited in the alveolar (A) and tracheo-bronchial (TB) regions was estimated by an AeroTrak 9000 nanoparticle monitor. An average mass concentration of particles during the process was 6-fold higher than that before its start, while a 3-fold increase in the average number concentration of particles within the dimension range 10-1000 nm and 10-100 nm was observed during the process. At the same time a 4-fold increase was found in the surface area concentration of the particles potentially deposited in the A and TB regions. During the process of carbon black handling and packing a significantly higher values of each of the analysed parameters, characterizing the exposure to ultrafine particles, were noted. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Applications of LIBS for determination of ionic species (NaCl) in electrical cables for investigation of electrical breakdown

NASA Astrophysics Data System (ADS)

Gondal, M. A.; Shwehdi, M. H.; Khalil, A. A. I.

2011-12-01

The formation of water trees in high-voltage cables can wreak havoc to power systems. The water tree is produced within the high voltage cable insulator when impurities like sodium and magnesium present in the insulating material react with moist soil to form chlorides. This water tree causes electrical breakdown by short circuiting the metallic conductor and the earth. In this paper we use laser-induced breakdown spectroscopy (LIBS) to detect the potentially dangerous elements that form the water tree in the insulating cable. The LIBS system used for this work consists of the fundamental (1064 nm) of a Nd:YAG laser, four spectrometer modules that cover the visible and near-UV spectral ranges and an ICCD camera with proper delay and gating sequence. With this arrangement we were able to measure the elemental concentrations of trace metals present in the insulating cable. The concentrations measured with our LIBS system were counter checked by a standard technique like inductively coupled plasma (ICP) emission spectrometry. The maximum concentrations for ionic species such as Ba (455.40 nm), Ca (393.36 nm), Cr (267.71 nm), Fe (259.94 nm), Cl (542.3 nm), Mg (516.7 nm), Mn (257.61 nm), Na (589.59 nm) and Ti (334.18 nm) are 20.6, 43.2, 1.6, 148.4, 24.2, 22.1, 4.2, 39.56 and 4.35 ppm, respectively. The relative accuracy of our LIBS system for various elements as compared with the ICP method is in the range of 0.03-0.6 at 2.5% error confidence.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking.

PubMed

Dennekamp, M; Howarth, S; Dick, C A; Cherrie, J W; Donaldson, K; Seaton, A

2001-08-01

To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens. Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NO(x)) were measured by a chemiluminescent ML9841A NO(x) analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm. High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NO(X) were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide. Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NO(x) might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.

A supersensitive silver nanoprobe based aptasensor for low cost detection of malathion residues in water and food samples

NASA Astrophysics Data System (ADS)

Bala, Rajni; Mittal, Sherry; Sharma, Rohit K.; Wangoo, Nishima

2018-05-01

In the present study, we report a highly sensitive, rapid and low cost colorimetric monitoring of malathion (an organophosphate insecticide) employing a basic hexapeptide, malathion specific aptamer (oligonucleotide) and silver nanoparticles (AgNPs) as a nanoprobe. AgNPs are made to interact with the aptamer and peptide to give different optical responses depending upon the presence or absence of malathion. The nanoparticles remain yellow in color in the absence of malathion owing to the binding of aptamer with peptide which otherwise tends to aggregate the particles because of charge based interactions. In the presence of malathion, the agglomeration of the particles occurs which turns the solution orange. Furthermore, the developed aptasensor was successfully applied to detect malathion in various water samples and apple. The detection offered high recoveries in the range of 89-120% with the relative standard deviation within 2.98-4.78%. The proposed methodology exhibited excellent selectivity and a very low limit of detection i.e. 0.5 pM was achieved. The developed facile, rapid and low cost silver nanoprobe based on aptamer and peptide proved to be potentially applicable for highly selective and sensitive colorimetric sensing of trace levels of malathion in complex environmental samples. Figure S2. HPLC Chromatogram of KKKRRR. Figure S3. UV- Visible spectra of AgNPs in the presence of increasing peptide concentrations. Inset shows respective color changes of AgNPs with peptide concentrations ranging from 0.1 mM to 100 mM (a to e). Figure S4. UV- Visible spectra of AgNPs in the presence 10 mM peptide and varying aptamer concentrations. Inset shows the corresponding color changes. a to e shows aptamer concentrations ranging from 10 nM to 1000 nM. Figure S5. Interference Studies. Ratio of A520 nm/390 nm of AgNPs in the presence of 10 mM peptide, 500 nM aptamer, 0.5 nM malathion and 0.5 mM interfering components i.e. sodium, potassium, calcium, alanine, arginine, aspartic acid, ascorbic acid (AA) and glucose. Figure S6. (A) Absorbance spectra of AgNPs with increasing malathion concentrations. (B) Calibration plot for spiked lake water. Inset shows their respective images where a to g represents malathion concentrations from 0.01 nM to 0.75 nM. Each point represents an average of three individual measurements and error bars indicate standard deviation. Figure S7. (A) Absorbance spectra of AgNPs with increasing malathion concentrations in spiked tap water samples. (B) Calibration plot for the biosensor. Inset represents the color changes. a to g represents varying malathion concentrations from 0.01 nM to 0.75 nM. Each point represents an average of three individual measurements and error bars indicate standard deviation. Figure S8. (A) Absorbance spectra of AgNPs in the presence of different malathion concentrations in spiked apple samples. (B) Calibration plot for spiked apple. Inset displays the corresponding color changes. a to g shows the color of solutions having malathion concentrations from 0.01 nM to 0.75 nM. Each point represents an average of three individual measurements and error bars indicate standard deviation.

Assessment of analytical methods to determine pyrethroids content of bednets.

PubMed

Castellarnau, Marc; Ramón-Azcón, Javier; Gonzalez-Quinteiro, Yolanda; López, Jordi F; Grimalt, Joan O; Marco, María-Pilar; Nieuwenhuijsen, Mark; Picado, Albert

2017-01-01

To present and evaluate simple, cost-effective tests to determine the amount of insecticide on treated materials. We developed and evaluated a competitive immunoassay on two different platforms: a label-free impedimetric biosensor (EIS biosensor) and a lateral flow. Both approaches were validated by gas chromatography (GC) and ELISA, gold standards for analytical methods and immunoassays, respectively. Finally, commercially available pyrethroid-treated ITN samples were analysed. Different extraction methods were evaluated. Insecticide extraction by direct infusion of the ITN samples with dichloromethane and dioxane showed recovery efficiencies around 100% for insecticide-coated bednets, and >70% for insecticide-incorporated bednets. These results were comparable to those obtained with standard sonication methods. The competitive immunoassay characterisation with ELISA presented a dynamic range between 12 nm and 1.5 μm (coefficient of variation (CV) below 5%), with an IC 50 at 138 nm, and a limit of detection (LOD) of 3.2 nm. EIS biosensor had a linear range between 1.7 nm and 61 nm (CV around 14%), with an IC 50 at 10.4 nm, and a LOD of 0.6 nm. Finally, the lateral flow approach showed a dynamic range between 150 nm and 1.5 μm, an IC 50 at 505 nm and a LOD of 67 nm. ELISA can replace chromatography as an accurate laboratory technique to determine insecticide concentration in bednets. The lateral flow approach developed can be used to estimate ITN insecticide concentration in the field. This new technology, coupled to the new extraction methods, should provide reliable guidelines for ITN use and replacement in the field. © 2016 John Wiley & Sons Ltd.

Equilibrium Gold Nanoclusters Quenched with Biodegradable Polymers

PubMed Central

Murthy, Avinash K.; Stover, Robert J.; Borwankar, Ameya U.; Nie, Golay D.; Gourisankar, Sai; Truskett, Thomas M.; Sokolov, Konstantin V.; Johnston, Keith P.

2013-01-01

Although sub-100 nm nanoclusters of metal nanoparticles are of interest in many fields including biomedical imaging, sensors and catalysis, it has been challenging to control their morphologies and chemical properties. Herein, a new concept is presented to assemble equilibrium Au nanoclusters of controlled size by tuning the colloidal interactions with a polymeric stabilizer, PLA(1k)-b-PEG(10k)-b-PLA(1k). The nanoclusters form upon mixing a dispersion of ~5 nm Au nanospheres with a polymer solution followed by partial solvent evaporation. A weakly adsorbed polymer quenches the equilibrium nanocluster size and provides steric stabilization. Nanocluster size is tuned from ~20 nm to ~40 nm by experimentally varying the final Au nanoparticle concentration and the polymer/Au ratio, along with the charge on the initial Au nanoparticle surface. Upon biodegradation of the quencher, the nanoclusters reversibly and fully dissociate to individual ~5 nm primary particles. Equilibrium cluster size is predicted semi-quantitatively with a free energy model that balances short-ranged depletion and van der Waals attractions with longer-ranged electrostatic repulsion, as a function of the Au and polymer concentrations. The close spacings of the Au nanoparticles in the clusters produce strong NIR extinction over a broad range of wavelengths from 650 to 900 nm, which is of practical interest in biomedical imaging. PMID:23230905

Optical Studies of CaS:Eu, Sm Infrared Stimulable Phosphors

NASA Astrophysics Data System (ADS)

Tamura, Yasuaki; Shibukawa, Atsushi

1993-07-01

The photoluminescence (PL) and infrared stimulated luminescence (ISL) spectra of CaS:Eu,Sm infrared stimulable phosphors (ISPs) are studied. In addition, the concentration dependence of ISL intensity is examined. Sm3+- and Eu2+-related structures are found in both the PL excitation and emission spectra. Two types of Sm3+ are found, one of which exhibits strong emission at around 650 nm and the other, weak emission compared to the other emissions at around 565 nm and 605 nm. These are assigned to an asymmetric and a symmetric site, respectively. ISL excitation spectra coincide with the Eu2+ 4f7 to 4f65d1 and 4f66s1 transitions and range from 220 to 650 nm. ISL emission spectra coincide with the Eu2+ 4f65d1 to 4f7 transition and range from 550 to 750 nm. ISL stimulation spectra range from 0.8 μm to 1.7 μm and are thought to indicate the Sm2+ ion transition from 4f6 to 4f55d1. The maximum ISL intensity is obtained from a sample with Eu and Sm concentrations of 500 and 130 ppm, respectively.

Absorption spectrum of neat liquid benzene and its concentrated solutions in n-hexane from 220 to 170 nm

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

Saik, V.O.; Lipsky, S.

The electronic absorption spectrum of benzene has been obtained by phototransmission measurements over a concentration range from 0.005 M in n-hexane to the neat liquid at 11.2 M and over a spectral range that extends down to 170 nm. Good agreement is obtained with previously reported measurements on the neat liquid. The oscillator strength of the strongly allowed A{sub 1g} {yields} E{sub 1u} transition is maintained at ca. 1.0 as the benzene concentration increases but is accompanied by extensive redistribution of the intensity such that the optical cross section at the position of the absorption maximum (which shifts from 184{submore » .2} nm in dilute solution to 189{sub .5} nm in the neat liquid) reduces by a factor of 2.7. An explanation for these changes in terms of Lorentz field corrections to the complex dielectric constant is developed, and its implication to the assignment of the neat liquid absorption as a collective excitation is considered. 43 refs., 5 figs., 1 tab.« less

Real-world emission factors of fine and ultrafine aerosol particles for different traffic situations in Switzerland.

PubMed

Imhof, David; Weingartner, Ernest; Ordónez, Carlos; Gehrig, Robert; Hill, Matz; Buchmann, Brigitte; Baltensperger, Urs

2005-11-01

Extended field measurements of particle number (size distribution of particle diameters, D, in the range between 18 nm and 10 microm), surface area concentrations, and PM1 and PM10 mass concentrations were performed in Switzerland to determine traffic emissions using a comprehensive set of instruments. Measurements took place at roads with representative traffic regimes: at the kerbside of a motorway (120 km h(-1)), a highway (80-100 km h(-1)), and in an urban area with stop-and-go traffic (0-50 km h(-1)) regulated by light signals. Mean diurnal variations showed that the highest pollutant concentrations were during the morning rush hours, especially of the number density in the nanoparticle size range (D <50 nm). From the differences between up- and downwind concentrations (or differences between kerbside and background concentrations for the urban site), "real-life" emission factors were derived using NOx concentrations to calculate dilution factors. Particle number and volume emission factors of different size ranges (18-50 nm, 18-100 nm, and 18-300 nm) were derived for the total vehicle fleet and separated into a light-duty (LDV) and a heavy-duty vehicle (HDV) contribution. The total particle number emissions per vehicle were found to be about 11.7-13.5 x 10(14) particles km(-1) for constant speed (80-120 km h(-1) and 3.9 x 10(14) particles km(-1) for urban driving conditions. LDVs showed higher emission factors at constant high speed than under urban disturbed traffic flow. In contrast, HDVs emitted more air pollutants during deceleration and acceleration processes in stop-and-go traffic than with constant speed of about 80 km h(-1). On average, one HDV emits a 10-30 times higher amount of particulate air pollutants (in terms of both number and volume) than one LDV.

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

PubMed Central

Stahl, Christian; Albe, Karsten

2012-01-01

Summary Nanoparticles of Pt–Rh were studied by means of lattice-based Monte Carlo simulations with respect to the stability of ordered D022- and 40-phases as a function of particle size and composition. By thermodynamic integration in the semi-grand canonical ensemble, phase diagrams for particles with a diameter of 7.8 nm, 4.3 nm and 3.1 nm were obtained. Size-dependent trends such as the lowering of the critical ordering temperature, the broadening of the compositional stability range of the ordered phases, and the narrowing of the two-phase regions were observed and discussed in the context of complete size-dependent nanoparticle phase diagrams. In addition, an ordered surface phase emerges at low temperatures and low platinum concentration. A decrease of platinum surface segregation with increasing global platinum concentration was observed, when a second, ordered phase is formed inside the core of the particle. The order–disorder transitions were analyzed in terms of the Warren–Cowley short-range order parameters. Concentration-averaged short-range order parameters were used to remove the surface segregation bias of the conventional short-range order parameters. Using this procedure, it was shown that the short-range order in the particles at high temperatures is bulk-like. PMID:22428091

Dissolved methane concentrations in the water column and surface sediments of Hanna Shoal and Barrow Canyon, Northern Chukchi Sea

NASA Astrophysics Data System (ADS)

Lapham, Laura; Marshall, Kathleen; Magen, Cédric; Lyubchich, Viacheslav; Cooper, Lee W.; Grebmeier, Jacqueline M.

2017-10-01

Current estimates of methane (CH4) flux suggest that Arctic shelves may be a significant source of atmospheric CH4, a potent greenhouse gas. However, little information is known about the CH4 flux from most Arctic shelves, other than the East Siberian Arctic Shelf. We report here dissolved CH4 concentrations in the water column and within surface sediments of the Northern Chukchi Sea. We hypothesized that this area contains high concentrations of CH4 because it receives nutrient rich waters through the Bering Strait, promoting primary production that enhances an organic-rich material flux to the seafloor and eventual microbial methanogenesis in the sediments. In August 2012, as part of the Chukchi Sea Offshore Monitoring in Drilling Area (COMIDA) project, fourteen stations were sampled on Hanna Shoal, a shallow feature on the shelf, and ten stations across the undersea Barrow Canyon. On Hanna Shoal, water column CH4 concentrations ranged from 14 to 74 nM, and surface concentrations were up to 15 times supersaturated in CH4 compared to equilibrium with the average atmospheric concentrations (3 nM). CH4 concentrations at the sediment-water interface were around 1,500 nM, and typically increased with depth in the sediment. At the head of Barrow Canyon, water column CH4 concentrations ranged from 5 to 46 nM, with the highest concentrations in the deepest waters that were sampled (118 m). Overall, the calculated fluxes to the atmosphere ranged from 1 to 80 μmol CH4 m-2 d-1 for Hanna Shoal and 4 to 17 μmol CH4 m-2 d-1 across the Barrow Canyon stations. Although there was a large range in these fluxes, the average atmospheric flux (20 μmol CH4 m-2 d-1) across Hanna Shoal was 12 times lower than the flux reported from the East Siberian Arctic Shelf in summer. We conclude that while there is a positive flux of CH4 to the atmosphere, this part of the Chukchi Sea is not a significant source of atmospheric CH4 compared to the East Siberian Sea shelf.

Development of a ratiometric fluorescent urea biosensor based on the urease immobilized onto the oxazine 170 perchlorate-ethyl cellulose membrane.

PubMed

Dinh Duong, Hong; Il Rhee, Jong

2015-03-01

In this work, the oxazine 170 perchlorate (O17)-ethyl cellulose (EC) membrane was successfully applied in the fabrication of a urea-sensing membrane. The urea-sensing membrane was a double layer consisting of the O17-EC membrane and a layer of the enzyme urease entrapped into EC matrix. The sensing principle of urea was based on the hydrolysis reaction of urea under the catalysis of the urease to produce ammonia in water and also on the binding of ammonia with the dye O17 to create the shift in the emission wavelength from λ(em)=630 nm to λ(em)=565 nm. The data collected from the ratio of the fluorescence intensities at λ(em)=630 nm and λ(em)=565 nm was proportional to urea concentration. The urea-sensing membrane with the ratiometric method was used to measure the concentrations of urea in the range of 0.01-0.1 M with a limit of detection (LOD) of 0.027 mM and 0.1-1.0 M with LOD of 0.224 mM. It showed fast response time, high reversibility and long-term stability in this concentration range. The recovery percentage of urea concentrations of the urea-sensing membrane for two kinds of biological urine solutions (BU1, BU2) was around 85-118%. The measured results were in good agreement with standard urea concentrations in the range of 0.06 M to 1.0 M. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical properties of cytostatic drugs used in cancer treatment

NASA Astrophysics Data System (ADS)

Pascu, Mihail-Lucian; Mogos, Ioan; Enescu, Mironel; Staicu, Angela; Truica, Sorina; Voicu, Letitia; Gazdaru, Doina M.; Pascu, Mihaela O.; Radu, Alina

2001-10-01

A spectroscopical characterization of methotrexate, cytostatic drug used frequently in cancer therapy, was performed. The absorption, emission and excitation spectra were measured for methotrexate solutions in natural saline and sodium hydroxide at concentration in the range 10-5 M -10-6 M and pH 8.4. The absorption bands are noticed in the spectral range 250 nm - 450 nm. The fluorescence excitation was made at 340 nm and 370 nm; the fluorescence emission was detected in the spectral range 400 nm - 500 nm with a maximum at 450 nm. The behavior of absorption and fluorescence spectra of methotrexate solution exposed to uv-visible light was investigated. The irradiation was made using an Xe lamp (emission between 325 nm and 420 nm and power density of 11 mW/cm2). The exposure time was between 15 min. and 3 h. Major modifications on absorption bands for irradiation times longer than 1 hour were observed. Furthermore, the methotrexate solutions become strongly fluorescent after irradiation. The observed changes are not linear with the exposure time indicating complex photochemical processes which implies, at least, one intermediate product.

Time and size resolved Measurement of Mass Concentration at an Urban Site

NASA Astrophysics Data System (ADS)

Karg, E.; Ferron, G. A.; Heyder, J.

2003-04-01

Time- and size-resolved measurements of ambient particles are necessary for modelling of atmospheric particle transport, the interpretation of particulate pollution events and the estimation of particle deposition in the human lungs. In the size range 0.01 - 2 µm time- and size-resolved data are obtained from differential mobility and optical particle counter measurements and from gravimetric filter analyses on a daily basis (PM2.5). By comparison of the time averaged and size integrated particle volume concentration with PM2.5 data, an average density of ambient particles can be estimated. Using this density, the number concentration data can be converted in time- and size-resolved mass concentration. Such measurements were carried out at a Munich downtown crossroads. The spectra were integrated in the size ranges 10 - 100 nm, 100 - 500 nm and 500 - 2000 nm. Particles in these ranges are named ultrafine, fine and coarse particles. These ranges roughly represent freshly emitted particles, aged/accumulated particles and particles entrained by erosive processes. An average number concentration of 80000 1/cm3 (s.d. 67%), a particle volume concentration of 53 µm3/cm3 (s.d. 76%) and a PM2.5 mass concentration of 27 µg/m3 was found. These particle volume- and PM2.5 data imply an average density of 0.51 g/cm3. Average number concentration showed 95.3%, 4.7% and 0.006% of the total particle concentration in the size ranges mentioned above. Mass concentration was 14.7%, 80.2% and 5.1% of the total, assuming the average density to be valid for all particles. The variability in mass concentration was 94%, 75% and 33% for the three size ranges. Nearly all ambient particles were in the ultrafine size range, whereas most of the mass concentration was in the fine size range. However, a considerable mass fraction of nearly 15% was found in the ultrafine size range. As the sampling site was close to the road and traffic emissions were the major source of the particles, 1) the density was very low due to agglomerated and porous structures of freshly emitted combustion particles and 2) the variability was highest in the ultrafine range, obviously correlated to traffic activity and lowest in the micron size range. In conclusion, almost all ambient particles were ultrafine particles, whereas most of the particle mass was associated with fine particles. Nevertheless, a considerable mass fraction was found in the ultrafine size range. These particles had a very low density so that they can be considered as agglomerated and porous particles emitted from vehicles passing the crossroads. Therefore they showed a much higher variation in mass concentration than the fine and coarse particles.

Exposure Characteristics of Nanoparticles as Process By-products for the Semiconductor Manufacturing Industry.

PubMed

Choi, Kwang-Min; Kim, Jin-Ho; Park, Ju-Hyun; Kim, Kwan-Sick; Bae, Gwi-Nam

2015-01-01

This study aims to elucidate the exposure properties of nanoparticles (NPs; <100 nm in diameter) in semiconductor manufacturing processes. The measurements of airborne NPs were mainly performed around process equipment during fabrication processes and during maintenance. The number concentrations of NPs were measured using a water-based condensation particle counter having a size range of 10-3,000 nm. The chemical composition, size, and shape of NPs were determined by scanning electron microscopy and transmission electron microscopy techniques equipped with energy dispersive spectroscopy. The resulting concentrations of NPs ranged from 0.00-11.47 particles/cm(3). The concentration of NPs measured during maintenance showed a tendency to increase, albeit incrementally, compared to that measured during normal conditions (under typical process conditions without maintenance). However, the increment was small. When comparing the mean number concentration and standard deviation (n ± σ) of NPs, the chemical mechanical polishing (CMP) process was the highest (3.45 ± 3.65 particles/cm(3)), and the dry etch (ETCH) process was the lowest (0.11 ± 0.22 particles/cm(3)). The major NPs observed were silica (SiO2) and titania (TiO2) particles, which were mainly spherical agglomerates ranging in size from 25-280 nm. Sampling of semiconductor processes in CMP, chemical vapor deposition, and ETCH reveled NPs were <100 nm in those areas. On the other hand, particle size exceeded 100 nm in diffusion, metallization, ion implantation, and wet cleaning/etching process. The results show that the SiO2 and TiO2 are the major NPs present in semiconductor cleanroom environments.

Toxic effects of tributyltin and its metabolites on harbour seal (Phoca vitulina) immune cells in vitro.

PubMed

Frouin, Héloïse; Lebeuf, Michel; Saint-Louis, Richard; Hammill, Mike; Pelletier, Emilien; Fournier, Michel

2008-11-21

The widespread environmental contamination, bioaccumulation and endocrine disruptor effects of butyltins (BTs) to wildlife are well documented. Although suspected, potential effects of BTs exposure on the immune system of marine mammals have been little investigated. In this study, we assessed the effects of tributyltin (TBT) and its dealkylated metabolites dibutyltin (DBT) and monobutyltin (MBT) on the immune responses of harbour seals. Peripheral blood mononuclear cells isolated from pup and adult harbour seals were exposed in vitro to varying concentrations of BTs. DBT resulted in a significant decrease at 100 and 200 nM of phagocytotic activity and reduced significantly phagocytic efficiency at 200 nM in adult seals. There was no effect in phagocytosis with TBT and MBT. In pups, the highest concentration (200 nM) of DBT inhibited phagocytic efficiency. A reduction of tumor-killing capacity of adult natural killer (NK) cells occurred when leukocytes were incubated in vitro with 50 nM DBT and 200 nM TBT for 24h. In adult seals, T-lymphocyte proliferation was significantly suppressed when the cells were exposed to 200 nM TBT and 100 nM DBT. In pups, the proliferative response increased after an exposure to 100 nM TBT and 50 nM DBT, but decreased with 200 nM TBT and 100 nM DBT. The immune functions were more affected by BTs exposure in adults than in pups, suggesting that other unsuspected mechanisms could trigger immune parameters in pups. The toxic potential of BTs followed the order of DBT>TBT>MBT. BT concentrations of harbour seal pups from the St. Lawrence Estuary (Bic National Park) ranged between 0.1-0.4 ng Sn/g wet weight (ww) and 1.2-13.4 ng Sn/g ww in blood and blubber, respectively. For these animals, DBT concentrations were consistently below the quantification limit of 0.04 ng Sn/g ww in blood and 0.2 ng Sn/g ww in blubber. Results suggest that concentrations measured in pups are considered too low to induce toxic effects to their immune system during first days of life. However, based on our in vitro results, we hypothesize that BTs, and DBT in particular, could pose a serious threat to the immune functions in free-ranging harbour seal adults.

Optical studies of CaS:Eu,Sm infrared stimulable phosphors

NASA Astrophysics Data System (ADS)

Tamura, Yasuaki; Shibukawa, Atsushi

1993-07-01

The photoluminescence (PL) and infrared stimulated luminescence (ISL) spectra of CaS:Eu,Sm infrared stimulable phosphors (ISPs) are studied. In addition, the concentration dependence of ISL intensity is examined. Sm(3+) and Eu(2+) related structures are found in both the PL excitation and emission spectra. Two types of Sm(3+) are found, one of which exhibits strong emission at around 650 nm and the other weak emission compared to the other emissions at around 565 nm and 605 nm. These are assigned to an asymmetric and a symmetric site, respectively. ISL excitation spectra coincide with the Eu(2+) 4f(sup 7) to 4f(sup 6)5d(sup 1) and 4f(sup 6)6s(sup 1) transitions and range from 220 to 650 nm. ISL emission spectra coincide with the Eu(2+) 4f(sup 6)5d(sup 1) to 4f(sup 7) transition and range from 550 to 750 nm. ISL stimulation spectra range from 0.8 micron to 1.7 micron and are thought to indicate the Sm(2+) ion transition from 4f(sup 6) to 4f(sup 5)5d(sup 1). The maximum ISL intensity is obtained from a sample with Eu and Sm concentrations of 500 and 130 ppm, respectively.

Compatible validated spectrofluorimetric and spectrophotometric methods for determination of vildagliptin and saxagliptin by factorial design experiments.

PubMed

Abdel-Aziz, Omar; Ayad, Miriam F; Tadros, Mariam M

2015-04-05

Simple, selective and reproducible spectrofluorimetric and spectrophotometric methods have been developed for the determination of vildagliptin and saxagliptin in bulk and their pharmaceutical dosage forms. The first proposed spectrofluorimetric method is based on the dansylation reaction of the amino group of vildagliptin with dansyl chloride to form a highly fluorescent product. The formed product was measured spectrofluorimetrically at 455 nm after excitation at 345 nm. Beer's law was obeyed in a concentration range of 100-600 μg ml(-1). The second proposed spectrophotometric method is based on the charge transfer complex of saxagliptin with tetrachloro-1,4-benzoquinone (p-chloranil). The formed charge transfer complex was measured spectrophotometrically at 530 nm. Beer's law was obeyed in a concentration range of 100-850 μg ml(-1). The third proposed spectrophotometric method is based on the condensation reaction of the primary amino group of saxagliptin with formaldehyde and acetyl acetone to form a yellow colored product known as Hantzsch reaction, measured at 342.5 nm. Beer's law was obeyed in a concentration range of 50-300 μg ml(-1). All the variables were studied to optimize the reactions' conditions using factorial design. The developed methods were validated and proved to be specific and accurate for quality control of vildagliptin and saxagliptin in their pharmaceutical dosage forms. Copyright © 2015. Published by Elsevier B.V.

Compatible validated spectrofluorimetric and spectrophotometric methods for determination of vildagliptin and saxagliptin by factorial design experiments

NASA Astrophysics Data System (ADS)

Abdel-Aziz, Omar; Ayad, Miriam F.; Tadros, Mariam M.

2015-04-01

Simple, selective and reproducible spectrofluorimetric and spectrophotometric methods have been developed for the determination of vildagliptin and saxagliptin in bulk and their pharmaceutical dosage forms. The first proposed spectrofluorimetric method is based on the dansylation reaction of the amino group of vildagliptin with dansyl chloride to form a highly fluorescent product. The formed product was measured spectrofluorimetrically at 455 nm after excitation at 345 nm. Beer's law was obeyed in a concentration range of 100-600 μg ml-1. The second proposed spectrophotometric method is based on the charge transfer complex of saxagliptin with tetrachloro-1,4-benzoquinone (p-chloranil). The formed charge transfer complex was measured spectrophotometrically at 530 nm. Beer's law was obeyed in a concentration range of 100-850 μg ml-1. The third proposed spectrophotometric method is based on the condensation reaction of the primary amino group of saxagliptin with formaldehyde and acetyl acetone to form a yellow colored product known as Hantzsch reaction, measured at 342.5 nm. Beer's law was obeyed in a concentration range of 50-300 μg ml-1. All the variables were studied to optimize the reactions' conditions using factorial design. The developed methods were validated and proved to be specific and accurate for quality control of vildagliptin and saxagliptin in their pharmaceutical dosage forms.

Long-term study of urban ultrafine particles and other pollutants

NASA Astrophysics Data System (ADS)

Wang, Yungang; Hopke, Philip K.; Chalupa, David C.; Utell, Mark J.

2011-12-01

Continuous measurements of number size distributions of ultrafine particles (UFPs) and other pollutants (PM 2.5, SO 2, CO and O 3) have been performed in Rochester, New York since late November 2001. The 2002-2009 average number concentrations of particles in three size ranges (10-50 nm, 50-100 nm and 100-500 nm) were 4730 cm -3, 1838 cm -3, and 1073 cm -3, respectively. The lowest annual average number concentrations of particles in 10-50 nm and 50-100 nm were observed during 2008-2009. The lowest monthly average number concentration of 10-50 nm particles was observed in July and the highest in February. The daily patterns of 10-50 nm particles had two peaks at early morning (7-8 AM) and early afternoon (2 PM). There was a distinct declining trend in the peak number concentrations from 2002-2005 to 2008-2009. Large reductions in SO 2 concentrations associated with northerly winds between 2007 and 2009 were observed. The most significant annual decrease in the frequency of morning particle nucleation was observed from 2005 to 2007. The monthly variation in the morning nucleation events showed a close correlation with number concentrations of 10-50 nm particles ( r = 0.89). The frequency of the local SO 2-related nucleation events was much higher before 2006. All of these results suggest significant impacts of highway traffic and industrial sources. The decrease in particle number concentrations and particle nucleation events likely resulted from a combination of the U.S. EPA 2007 Heavy-Duty Highway Rule implemented on October 1, 2006, the closure of a large coal-fired power plant in May 2008, and the reduction of Eastman Kodak emissions.

Noninvasive monitoring of intraocular pharmacokinetics of daunorubicin using fluorophotometry.

PubMed

Kizhakkethara, I; Li, X; el-Sayed, S; Khoobehi, B; Moshfeghi, D M; Rahimy, M; Peyman, G A

Daunorubicin is a cytotoxic drug, which, in nontoxic doses, is effective in preventing cellular proliferation in experimental vitreoretinopathy. We studied dose and clearance of daunorubicin in various ocular tissues using fluorophotometry techniques. In vitro tests: The emission of fluorescence from the daunorubicin solution having a concentration range of 0.1 to 10 micrograms/mL in phosphate buffer was measured using an excitation wavelength range of 489 +/- 10 nm. The emission of fluorescence was measured at 514 nm; the linearity of the response was determined using linear regression analysis. There is a fluorescence peak of daunorubicin at 485 nm. The validity and reproducibility of the method were examined. In vivo tests: The rabbits were randomized into three groups and daunorubicin concentrations of 4, 6, or 8 micrograms/mL were injected into the vitreous. Fluorophotometry scanning from the retina to the anterior chamber was performed with a commercially available fluorophotometer at various times up to 48 hours after injection to quantify fluorescence emission of daunorubicin. The standard curve of fluorescence versus concentration of daunorubicin was linear in the range of 0.1 to 8 micrograms/mL. It was sensitive up to 0.1 microgram. The daunorubicin time concentration profile showed a dose response relationship over the 48-hour period studied. The half-life of daunorubicin in the vitreous was about 5 hours. We performed fluorophotometry using a fluorophotometer whose exciter emits light at 489 nm, which is very close to an absorption peak of daunorubicin. These two values are close enough to obviate the need for modifying the commercial fluorophotometer. Therefore the concentration of daunorubicin in the vitreous cavity can be measured noninvasively.

Ultrafine particles and nitrogen oxides generated by gas and electric cooking

PubMed Central

Dennekamp, M; Howarth, S; Dick, C; Cherrie, J; Donaldson, K; Seaton, A

2001-01-01

OBJECTIVES—To measure the concentrations of particles less than 100 nm diameter and of oxides of nitrogen generated by cooking with gas and electricity, to comment on possible hazards to health in poorly ventilated kitchens.
METHODS—Experiments with gas and electric rings, grills, and ovens were used to compare different cooking procedures. Nitrogen oxides (NOx) were measured by a chemiluminescent ML9841A NOx analyser. A TSI 3934 scanning mobility particle sizer was used to measure average number concentration and size distribution of aerosols in the size range 10-500 nm.
RESULTS—High concentrations of particles are generated by gas combustion, by frying, and by cooking of fatty foods. Electric rings and grills may also generate particles from their surfaces. In experiments where gas burning was the most important source of particles, most particles were in the size range 15-40 nm. When bacon was fried on the gas or electric rings the particles were of larger diameter, in the size range 50-100 nm. The smaller particles generated during experiments grew in size with time because of coagulation. Substantial concentrations of NOX were generated during cooking on gas; four rings for 15 minutes produced 5 minute peaks of about 1000 ppb nitrogen dioxide and about 2000 ppb nitric oxide.
CONCLUSIONS—Cooking in a poorly ventilated kitchen may give rise to potentially toxic concentrations of numbers of particles. Very high concentrations of oxides of nitrogen may also be generated by gas cooking, and with no extraction and poor ventilation, may reach concentrations at which adverse health effects may be expected. Although respiratory effects of exposure to NOx might be anticipated, recent epidemiology suggests that cardiac effects cannot be excluded, and further investigation of this is desirable.


Keywords: cooking fuels; nitrogen oxides; ultrafine particles PMID:11452045

Simultaneous Estimation of Amlodipine Besilate and Olmesartan Medoxomil in Pharmaceutical Dosage Form

PubMed Central

Wankhede, S. B.; Wadkar, S. B.; Raka, K. C.; Chitlange, S. S.

2009-01-01

Two UV Spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate and olmesartan medoxomil in tablet dosage form. First UV spectrophotometric method was a determination using the simultaneous equation method at 237.5 nm and 255.5 nm over the concentration range 10-50 μg/ml and 10-50 μg/ml, for amlodipine besilate and olmesartan medoxomil with accuracy 100.09%, and 100.22% respectively. Second UV spectrophotometric method was a determination using the area under curve method at 242.5-232.5 nm and 260.5-250.5 nm over the concentration range of 10-50 μg/ml and 10-50 μg/ml, for amlodipine besilate and olmesartan medoxomil with accuracy 100.10%, and 100.48%, respectively. In reverse phase high performance liquid chromatography analysis carried out using 0.05M potassuim dihydrogen phosphate buffer:acetonitrile (50:50 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d.×250 mm) column as the stationery phase with detection wavelength of 238 nm. Flow rate was 1.0 ml/min. Retention time for amlodipine besilate and olmesartan medoxomil were 3.69 and 5.36 min, respectively. Linearity was obtained in the concentration range of 4-20 μg/ml and 10-50 μg/ml for amlodipine besilate and olmesartan medoxomil, respectively. Proposed methods can be used for the estimation of amlodipine besilate and olmesartan medoxomil in tablet dosage form provided all the validation parameters are met. PMID:20502580

Transition of carbon nanostructures in heptane diffusion flames

NASA Astrophysics Data System (ADS)

Hu, Wei-Chieh; Hou, Shuhn-Shyurng; Lin, Ta-Hui

2017-02-01

The flame synthesis has high potential in industrial production of carbon nanostructure (CNS). Unfortunately, the complexity of combustion chemistry leads to less controlling of synthesized products. In order to improve the understanding of the relation between flames and CNSs synthesized within, experiments were conducted through heptane flames in a stagnation-point liquid-pool system. The operating parameters for the synthesis include oxygen supply, sampling position, and sampling time. Two kinds of nanostructures were observed, carbon nanotube (CNT) and carbon nano-onion (CNO). CNTs were synthesized in a weaker flame near extinction. CNOs were synthesized in a more sooty flame. The average diameter of CNTs formed at oxygen concentration of 15% was in the range of 20-30 nm. For oxygen concentration of 17%, the average diameter of CNTs ranged from 24 to 27 nm, while that of CNOs was around 28 nm. For oxygen concentration of 19%, the average diameter of CNOs produced at the sampling position 0.5 mm below the flame front was about 57 nm, while the average diameters of CNOs formed at the sampling positions 1-2.5 mm below the flame front were in the range of 20-25 nm. A transition from CNT to CNO was observed by variation of sampling position in a flame. We found that the morphology of CNS is directly affected by the presence of soot layer due to the carbonaceous environment and the growth mechanisms of CNT and CNO. The sampling time can alter the yield of CNSs depending on the temperature of sampling position, but the morphology of products is not affected.

Fluorescence spectroscopy of Rhodamine 6G: concentration and solvent effects.

PubMed

Zehentbauer, Florian M; Moretto, Claudia; Stephen, Ryan; Thevar, Thangavel; Gilchrist, John R; Pokrajac, Dubravka; Richard, Katherine L; Kiefer, Johannes

2014-01-01

Rhodamine 6G (R6G), also known as Rhodamine 590, is one of the most frequently used dyes for application in dye lasers and as a fluorescence tracer, e.g., in the area of environmental hydraulics. Knowing the spectroscopic characteristics of the optical emission is key to obtaining high conversion efficiency and measurement accuracy, respectively. In this work, solvent and concentration effects are studied. A series of eight different organic solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol, n-pentanol, acetone, and dimethyl sulfoxide (DMSO)) are investigated at constant dye concentration. Relatively small changes of the fluorescence spectrum are observed for the different solvents; the highest fluorescence intensity is observed for methanol and lowest for DMSO. The shortest peak wavelength is found in methanol (568 nm) and the longest in DMSO (579 nm). Concentration effects in aqueous R6G solutions are studied over the full concentration range from the solubility limit to highly dilute states. Changing the dye concentration provides tunability between ∼550 nm in the dilute case and ∼620 nm at high concentration, at which point the fluorescence spectrum indicates the formation of R6G aggregates. Copyright © 2013 Elsevier B.V. All rights reserved.

Multi-wavelength dye concentration determination for enzymatic assays: evaluation of chromogenic para-nitrophenol over a wide pH range.

PubMed

Max, Jean-Joseph; Meddeb-Mouelhi, Fatma; Beauregard, Marc; Chapados, Camille

2012-12-01

Enzymatic assays need robust, rapid colorimetric methods that can follow ongoing reactions. For this, we developed a highly accurate, multi-wavelength detection method that could be used for several systems. Here, it was applied to the detection of para-nitrophenol (pNP) in basic and acidic solutions. First, we confirmed by factor analysis that pNP has two forms, with unique spectral characteristics in the 240 to 600 nm range: Phenol in acidic conditions absorbs in the lower range, whereas phenolate in basic conditions absorbs in the higher range. Thereafter, the method was used for the determination of species concentration. For this, the intensity measurements were made at only two wavelengths with a microtiter plate reader. This yielded total dye concentration, species relative abundance, and solution pH value. The method was applied to an enzymatic assay. For this, a chromogenic substrate that generates pNP after hydrolysis catalyzed by a lipase from the fungus Yarrowia lipolytica was used. Over the pH range of 3-11, accurate amounts of acidic and basic pNP were determined at 340 and 405 nm, respectively. This method surpasses the commonly used single-wavelength assay at 405 nm, which does not detect pNP acidic species, leading to activity underestimations. Moreover, alleviation of this pH-related problem by neutralization is not necessary. On the whole, the method developed is readily applicable to rapid high-throughput of enzymatic activity measurements over a wide pH range.

In-vitro interaction of tafenoquine and chloroquine in Plasmodium falciparum from northwestern Thailand.

PubMed

Vollnberg, Anke; Prajakwong, Somsak; Sirichaisinthop, Jeeraphat; Wiedermann, Gerhard; Wernsdorfer, Gunther; Wernsdorfer, Walther H

2003-01-01

The blood schizontocidal, pharmacodynamic interaction between tafenoquine (WR 238605--a 5-phenoxyprimaquine derivative--and chloroquine was investigated, using an in-vitro test for the inhibition of schizont maturation, in 15 fresh isolates of Plasmodium falciparum that originated from northwestern Thailand and neighbouring Myanmar. In this area the parasite is highly resistant to chloroquine. The geometric mean cut-off concentrations of schizont maturation for tafenoquine and chloroquine were 5261 nM and 7638 nM, respectively. With a mixture of tafenoquine and chloroquine, the mean cut-off concentration was 5252 nM, corresponding to 389 nM tafenoquine + 4863 nM chloroquine. Further analysis showed that the interaction between tafenoquine and chloroquine was additive within the range of EC20 and EC77. At concentrations higher than the EC77, interaction was moderately synergistic. While tafenoquine did not reverse the resistance to chloroquine to the degree of clinically relevant sensitivity, there was evidence that the blood schizontocidal efficacy of tafenoquine would be enhanced in the presence of chloroquine.

Estimation of leaf nitrogen concentration on winter wheat by multispectral imaging

NASA Astrophysics Data System (ADS)

Leemans, Vincent; Marlier, Guillaume; Destain, Marie-France; Dumont, Benjamin; Mercatoris, Benoit

2017-04-01

Precision agriculture can be considered as one of the solutions to optimize agricultural practice such as nitrogen fertilization. Nitrogen deficiency is a major limitation to crop production worldwide whereas excess leads to environmental pollution. In this context, some devices were developed as reflectance spot sensors for on-the-go applications to detect leaves nitrogen concentration deduced from chlorophyll concentration. However, such measurements suffer from interferences with the crop growth stage and the water content of plants. The aim of this contribution is to evaluate the nitrogen status in winter wheat by using multispectral imaging. The proposed system is composed of a CMOS camera and a set of filters ranged from 450 nm to 950 nm and mounted on a wheel which moves due to a stepper motor. To avoid the natural irradiance variability, a white reference is used to adjust the integration time. The segmentation of Photosynthetically Active Leaves is performed by using Bayes theorem to extract their mean reflectance. In order to introduce information related to the canopy architecture, i.e. the crop growth stage, textural attributes are also extracted from raw images at different wavelength ranges. Nc was estimated by partial least squares regression (R² = 0.94). The best attribute was homogeneity extracted from the gray level co-occurrence matrix (R² = 0.91). In order to select in limited number of filters, best subset selection was performed. Nc could be estimated by four filters (450 +/- 40 nm, 500 +/- 20 nm, 650 +/- 40 nm, 800 +/- 50 nm) (R² = 0.91).

Aerosol size distribution and new particle formation events in the suburb of Xi'an, northwest China

NASA Astrophysics Data System (ADS)

Peng, Yan; Liu, Xiaodong; Dai, Jin; Wang, Zhao; Dong, Zipeng; Dong, Yan; Chen, Chuang; Li, Xingmin; Zhao, Na; Fan, Chao

2017-03-01

Particle number concentration and size distribution are important for better understanding the characteristics of aerosols. However, their measurements are scarce in western China. Based on the first measurement of particle number size distribution (10-487 nm) in the suburb of Xi'an, northwest China from November 2013 to December 2014, the seasonal, monthly and diurnal average particle number concentrations were investigated, and the characteristics of new particle formation (NPF) events and their dependencies on meteorological parameters also discussed. The results showed that the annual average particle number concentrations in the nucleation (NNUC), Aitken (NAIT), and Accumulation (NACC) size ranges were 960 cm-3, 4457 cm-3, 3548 cm-3, respectively. The mean total particle number concentration (NTOT) was 8965 cm-3 and largely dominated by particles in Aitken mode. The number concentration was dominated by particles around 67.3 nm in spring, summer and fall, while about 89.8 nm in winter. The percentage of the ultrafine size range (UFP, particles of diameter below 100 nm) to total particle number concentration was 63.2%, 69.6%, 62.2% and 58.1% in four seasons. The diurnal variation of the nucleation mode particles was mainly influenced by NPF events in summer, while by both traffic densities and NPF events in spring, fall and winter. The diurnal variation of the number concentration of Aitken mode particles correlated with the traffic emission in spring, fall and winter, while in summer it more correlated with contribution of the growth of the nucleation mode particles. The burst of nucleation mode particles typically started in the daytime (08:15-16:05, LST). The growth rates of nucleated particles ranged from 2.8 to 10.7 nm h-1 with an average of 5.0 ± 1.9 nm h-1. Among observed 66 NPF events from 347 effective measurement days, 85 percent of their air masses came from north or northwest China, resulting in a low concentration of pre-existing particles, and only 15 percent came southerly from Qingling Mountains. Based on their growth rate, 64 and 36 percent of their subsequent particles, corresponding to types 1 and 2 NPF events, grew and seldom grew after the burst of nucleation mode particles. For type 1 NPF event, the nucleated particles could grow up to 40 nm or larger when surface winds shifted from westerly to easterly or southeasterly (from village areas). For type 2 NPF events, the particles kept almost unchanged when the winds stayed westerly. This implied that the surface wind direction with different emissions might play an important role in new particle growth in suburb of Xi'an.

Detection of lead nanoparticles in game meat by single particle ICP-MS following use of lead-containing bullets.

PubMed

Kollander, Barbro; Widemo, Fredrik; Ågren, Erik; Larsen, Erik H; Loeschner, Katrin

2017-03-01

This study investigated whether game meat may contain nanoparticles of lead from ammunition. Lead nanoparticles in the range 40 to 750 nm were detected by ICP-MS in single particle mode in game shot with lead-containing bullets. The median diameter of the detected nanoparticles was around 60 nm. The particle mass concentration ranged from 290 to 340 ng/g meat and the particle number concentrations from 27 to 50 million particles/g meat. The size limit of detection strongly depended on the level of dissolved lead and was in the range of 40 to 80 nm. In game meat sampled more than 10 cm away from the wound channel, no lead particles with a diameter larger than 40 nm were detected. In addition to dissolved lead in meat that originated from particulates, the presence of lead nano particles in game meat represents a hitherto unattended source of lead with a largely unknown toxicological impact to humans. Graphical Abstract Detection of lead nanoparticles in game meat by single particle ICP-MS following use of leadcontaining bullets.

Study of visible luminescence spectra from Nd3+ doped TPO glass upon 808 nm excitation

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar

2018-05-01

The Nd3+ doped TPO glasses have been prepared by melting and quenching method using the high temperature electric furnace. The upconversion (UC) spectra of Nd3+ doped TPO glasses at different concentration of rare ions have been recorded in the 400-700 nm wavelength range upon 808 nm laser excitation source. In the UC emission process, there are four bands centered at ˜495 nm, 546 nm, 602 nm and 653 nm respectively in the visible range were observed. But the green and red bands centered at˜546 nm and ˜653 nm corresponding to the 4G7/2 → 4I9/2 and 4G7/2 → 4I13/2 transitions respectively have been observed as the strong bands. The UC emission mechanism was observed as two photon process. The material can be used as a good NIR to visible upconverter and non-colour tunable display.

Linear and Non-Linear Thermal Lens Signal of the Fifth C-H Vibrational Overtone of Naphthalene in Liquid Solutions of Hexane

NASA Astrophysics Data System (ADS)

Manzanares, Carlos; Diaz, Marlon; Barton, Ann; Nyaupane, Parashu R.

2017-06-01

The thermal lens technique is applied to vibrational overtone spectroscopy of solutions of naphthalene in n-hexane. The pump and probe thermal lens technique is found to be very sensitive for detecting samples of low composition (ppm) in transparent solvents. In this experiment two different probe lasers: one at 488 nm and another 568 nm were used. The C-H fifth vibrational overtone spectrum of benzene is detected at room temperature for different concentrations. A plot of normalized integrated intensity as a function of concentration of naphthalene in solution reveals a non-linear behavior at low concentrations when using the 488 nm probe and a linear behavior over the entire range of concentrations when using the 568 nm probe. The non-linearity cannot be explained assuming solvent enhancement at low concentrations. A two color absorption model that includes the simultaneous absorption of the pump and probe lasers could explain the enhanced magnitude and the non-linear behavior of the thermal lens signal. Other possible mechanisms will also be discussed.

Interaction of tributyltin with 3,3',4,4',5-pentachlorobiphenyl-induced ethoxyresorufin O-deethylase activity in rat hepatoma cells.

PubMed

Kannan, K; Villeneuve, D L; Blankenship, A L; Giesy, J P

1998-11-13

Interaction of tributyltin (TBT) with 3,3',4,4',5-pentachlorobiphenyl (PCB-126)-induced ethoxyresorufin O-deethylase (EROD) activity was examined in vitro using H4IIE rat hepatoma cells. H4IIE cells were exposed to TBT and PCB-126, individually or in combination, at different concentrations. TBT was cytotoxic at concentrations greater than 98 nM. PCB-126 was not cytotoxic in the concentration range of 49 to 3140 pM. At concentrations greater than 49 nM, PCB-126 enhanced the cytotoxicity of TBT in the 24-98 nM range. In the absence of inducers of EROD activity, TBT significantly inhibited constitutive EROD activity in H4IIE cells in a concentration-dependent manner. EROD activity in H4IIE cells was significantly increased by exposure to PCB-126 alone. This effect was potentiated by coexposure to low, noncytotoxic concentrations of TBT. The induction of cytochrome P-4501A (CYP1A) activity in the presence of both an inducer (PCB-126) and low concentrations of an inhibitor (TBT) indicates that TBT does not interfere with the Ah receptor binding, but acts at the transcriptional level. Potentiation of EROD activity and cytotoxicity as a consequence of coexposure to PCB-126 and TBT is of considerable toxicological significance, given their coaccumulation in a variety of marine organisms.

Inhibition effect of engineered silver nanoparticles to bloom forming cyanobacteria

NASA Astrophysics Data System (ADS)

Thuy Duong, Thi; Son Le, Thanh; Thu Huong Tran, Thi; Kien Nguyen, Trung; Ho, Cuong Tu; Hien Dao, Trong; Phuong Quynh Le, Thi; Chau Nguyen, Hoai; Dang, Dinh Kim; Thu Huong Le, Thi; Thu Ha, Phuong

2016-09-01

Silver nanoparticle (AgNP) has a wide range antibacterial effect and is extensively used in different aspects of medicine, food storage, household products, disinfectants, biomonitoring and environmental remediation etc. In the present study, we examined the growth inhibition effect of engineered silver nanoparticles against bloom forming cyanobacterial M. aeruginosa strain. AgNPs were synthesized by a chemical reduction method at room temperature and UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM) showed that they presented a maximum absorption at 410 nm and size range between 10 and 18 nm. M. aeruginosa cells exposed during 10 d to AgNPs to a range of concentrations from 0 to 1 mg l-1. The changes in cell density and morphology were used to measure the responses of the M. aeruginosa to AgNPs. The control and treatment units had a significant difference in terms of cell density and growth inhibition (p < 0.05). Increasing the concentration of AgNPs, a reduction of the cell growths in all treatment was observed. The inhibition efficiency was reached 98.7% at higher concentration of AgNPs nanoparticles. The term half maximal effective concentration (EC50) based on the cell growth measured by absorbance at 680 nm (A680) was 0.0075 mg l-1. The inhibition efficiency was 98.7% at high concentration of AgNPs (1 mg l-1). Image of SEM and TEM reflected a shrunk and damaged cell wall indicating toxicity of silver nanoparticles toward M. aeruginosa.

Nondestructive NIR reflectance spectroscopic method for rapid fatty acid analysis of peanut seeds

USDA-ARS?s Scientific Manuscript database

NIR reflectance spectroscopy was used to analyze the fatty acid concentration present in breeder's peanut seeds samples, rapidly and nondestructively. Absorbance spectra were collected in the wavelength range from 400 nm to 2500 nm using a NIR spectrometer. Fatty acids, oleic, linoleic and palmitic ...

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

Mainali, M; Ngwa, W; Cifter, G

Purpose: The purpose of this research is to investigate the feasibility of using targeted cerium oxide nanoparticles (CONP) during APBI to protect healthy cells. Methods: In one approach, CONP are assumed to be incorporated in a micrometer-thick polymer film on the surface of routinely used mammosite balloon applicators for sustained in-situ release of the CONP. In case two, CONPs are administered directly into the lumpectomy cavity. The concentration of H{sub 2}O{sub 2} produced by ionizing radiation was estimated from previously published work using short range linear extrapolation. The assessment of CONPs concentration required to absorb corresponding H{sub 2}O{sub 2} tomore » protect healthy tissue was calculated. Fick’s Second law of diffusion was employed to determine the initial concentration of CONP needed to achieve the minimum concentration for radioprotection at distance 1 cm and 2 cm from the lumpectomy cavity during APBI. The study was carried out for different nanoparticle sizes. Results: The initial concentration of CONPs required to get desired radioprotection concentration at 1 cm and 2 cm after 7 days was found to be 0.4089 mg per Kg and 59.7605 g per Kg respectively for 2 nm size nanoparticles. Using concentrations of 5 mg per kg of CONP that have been shown to be used to confer radioprotection (for about 7.97 Gy) in experiments it was observed that 4.5631, 8.5286, 10.9247, 22.0408, 43.6796 and 65.5618 number of days are required to achieve radioprotection at 1 cm for CONP of sizes 2 nm, 3.8 nm, 5 nm, 10 nm, 20 nm, 30 nm, respectively. Conclusion: Our preliminary results show that smaller size (2 nm and 3.8 nm) CONP would be suitable as radio protectant during APBI because they took a reasonable number of days, i.e. less than 10 days to reach tissues of 1 cm or 2 cm thickness.« less

Methane fluxes from tropical coastal lagoons surrounded by mangroves, Yucatán, Mexico

NASA Astrophysics Data System (ADS)

Chuang, P.-C.; Young, M. B.; Dale, A. W.; Miller, L. G.; Herrera-Silveira, J. A.; Paytan, A.

2017-05-01

Methane concentrations in the water column and emissions to the atmosphere were determined for three tropical coastal lagoons surrounded by mangrove forests on the Yucatán Peninsula, Mexico. Surface water dissolved methane was sampled at different seasons over a period of 2 years in areas representing a wide range of salinities and anthropogenic impacts. The highest surface water methane concentrations (up to 8378 nM) were measured in a polluted canal associated with Terminos Lagoon. In Chelem Lagoon, methane concentrations were typically lower, except in the polluted harbor area (1796 nM). In the relatively pristine Celestún Lagoon, surface water methane concentrations ranged from 41 to 2551 nM. Methane concentrations were negatively correlated with salinity in Celestún, while in Chelem and Terminos high methane concentrations were associated with areas of known pollution inputs, irrespective of salinity. The diffusive methane flux from surface lagoon water to the atmosphere ranged from 0.0023 to 15 mmol CH4 m-2 d-1. Flux chamber measurements revealed that direct methane release as ebullition was up to 3 orders of magnitude greater than measured diffusive flux. Coastal mangrove lagoons may therefore be an important natural source of methane to the atmosphere despite their relatively high salinity. Pollution inputs are likely to substantially enhance this flux. Additional statistically rigorous data collected globally are needed to better consider methane fluxes from mangrove-surrounded coastal areas in response to sea level changes and anthropogenic pollution in order to refine projections of future atmospheric methane budgets.

Concentration and size dependence of peak wavelength shift on quantum dots in colloidal suspension

NASA Astrophysics Data System (ADS)

Rinehart, Benjamin S.; Cao, Caroline G. L.

2016-08-01

Quantum dots (QDs) are semiconductor nanocrystals that have significant advantages over organic fluorophores, including their extremely narrow Gaussian emission bands and broad absorption bands. Thus, QDs have a wide range of potential applications, such as in quantum computing, photovoltaic cells, biological sensing, and electronics. For these applications, aliasing provides a detrimental effect on signal identification efficiency. This can be avoided through characterization of the QD fluorescence signals. Characterization of the emissivity of CdTe QDs as a function of concentration (1 to 10 mg/ml aqueous) was conducted on 12 commercially available CdTe QDs (emission peaks 550 to 730 nm). The samples were excited by a 50-mW 405-nm laser with emission collected via a free-space CCD spectrometer. All QDs showed a redshift effect as concentration increased. On average, the CdTe QDs exhibited a maximum shift of +35.6 nm at 10 mg/ml and a minimum shift of +27.24 nm at 1 mg/ml, indicating a concentration dependence for shift magnitude. The concentration-dependent redshift function can be used to predict emission response as QD concentration is changed in a complex system.

Isolation of >1 nm Diameter Single-Wall Carbon Nanotube Species Using Aqueous Two-Phase Extraction.

PubMed

Fagan, Jeffrey A; Hároz, Erik H; Ihly, Rachelle; Gui, Hui; Blackburn, Jeffrey L; Simpson, Jeffrey R; Lam, Stephanie; Hight Walker, Angela R; Doorn, Stephen K; Zheng, Ming

2015-05-26

In this contribution we demonstrate the effective separation of single-wall carbon nanotube (SWCNT) species with diameters larger than 1 nm through multistage aqueous two-phase extraction (ATPE), including isolation at the near-monochiral species level up to at least the diameter range of SWCNTs synthesized by electric arc synthesis (1.3-1.6 nm). We also demonstrate that refined species are readily obtained from both the metallic and semiconducting subpopulations of SWCNTs and that this methodology is effective for multiple SWCNT raw materials. Using these data, we report an empirical function for the necessary surfactant concentrations in the ATPE method for separating different SWCNTs into either the lower or upper phase as a function of SWCNT diameter. This empirical correlation enables predictive separation design and identifies a subset of SWCNTs that behave unusually as compared to other species. These results not only dramatically increase the range of SWCNT diameters to which species selective separation can be achieved but also demonstrate that aqueous two-phase separations can be designed across experimentally accessible ranges of surfactant concentrations to controllably separate SWCNT populations of very small (∼0.62 nm) to very large diameters (>1.7 nm). Together, the results reported here indicate that total separation of all SWCNT species is likely feasible by the ATPE method, especially given future development of multistage automated extraction techniques.

[Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

PubMed

Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

2014-09-01

Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration.

Chasing Sources and Transports of Methane Plumes in the Northern Gulf of Mexico Using In Situ Sensors on Untethered Landers

NASA Astrophysics Data System (ADS)

Martens, C. S.; Mendlovitz, H.; Seim, H.; Lapham, L.; Magen, C.; Joye, S. B.; MacDonald, I. R.; Asper, V. L.; Diercks, A. R.

2016-02-01

In situ time-series measurements of light hydrocarbons, oxygen, temperature and bottom currents from landers and elevators in the benthic boundary layer (BBL) at multiple sites in the northern Gulf of Mexico reveal spatial and temporal variability in methane concentrations controlled by horizontal advection of methane-rich plumes originating from nearby natural oil and gas seeps. Multi-sensor systems deployed for several weeks within 1m of the seafloor at depths from 882 to 1622m revealed methane concentrations ranging from near atmospheric saturation (<3 nM) to over 4000 nM depending on seep proximity, current speed and direction. Methane concentrations observed in the BBL equal or exceed maximum near-bottom values seen in shipboard water column profiles analyzed by conventional gas chromatography. Continuous laser sensor methane measurements from mini-landers deployed in September 2015 at our Horn Dome and Bush Hill sites featuring numerous gas seeps revealed methane concentrations ranging from <3 to over 300 nM over two-week periods. Net current speeds in the BBL at our six lander sites in blocks GC600, OC26 and MC118 ranged from near zero to over 5 cm/s; instantaneous speeds ranged from near zero to over 30 cm/s. Near real-time acquisition of continuous hydrocarbon concentration and current data within the BBL and friction layer from untethered platforms provides important new opportunities for monitoring the impacts of natural seeps and accidental hydrocarbon releases. The instrumented approaches we have developed to simultaneously monitor methane sources and physical processes controlling plume development and transport will enable more effective responses to further accidental hydrocarbon releases.

Assessing the link between chlorophyll concentration and absorption line height at 676 nm over a broad range of water types.

PubMed

Nardelli, Schuyler C; Twardowski, Michael S

2016-10-31

The relationship between absorption at 676 nm normalized to chlorophyll-a, i.e., specific absorption aph*(676), and various optical and environmental properties is examined in extensive data sets from Case I and Case II waters found globally to assess drivers of variability such as pigment packaging. A better understanding of this variability could lead to more accurate estimates of chlorophyll concentrations from in situ optical measurements that may be made autonomously. Values of aph*(676) ranged from 0.00006 to 0.0944 m²/mg Chl a across all sites studied, but converged on median and mean values (n = 563) of 0.0108 and 0.0139 m²/mg Chl a respectively, with no apparent relationship with various optical properties, latitude, coastal or open ocean environment, depth, temperature, salinity, photoadaptation, ecosystem health, or albedo. Relative consistency in aph* across such diverse water types and the full range in chlorophyll concentration suggests a single aph* may be used to estimate chlorophyll concentration from absorption measurements with better accuracy than currently thought.

Colorimetric detection of Cr3+ using gold nanoparticles functionalized with 4-amino hippuric acid

NASA Astrophysics Data System (ADS)

Jin, Weiwei; Huang, Pengcheng; Chen, Yueji; Wu, Fangying; Wan, Yiqun

2015-09-01

A facile and effective technique for monitoring Cr3+ concentration based on 4-amino hippuric acid (PAH) decorated Au nanoparticles (PAH-AuNPs) is introduced. The modified AuNPs were easily aggregated in the presence of Cr3+, resulting in the color change from red to violet or blue, which is in response to the surface plasmon absorption of dispersed or aggregated nanoparticles. Under the optimized conditions, a good linear relationship (correlation coefficient r = 0.998) was obtained between the ratio of the absorbance at 635 nm to that at 520 nm ( A 635 nm/ A 520 nm), and the concentration of Cr3+ was over the range of 5.0-120 µM with detection limit of 1.17 µM. This method exhibited excellent selectivity for Cr3+ over other tested heavy metal ions. Furthermore, there was no significant difference for the parameters of calibration equation between the presence and absence of ethylenediamine tetraacetic acid (EDTA), which suggests that the method can be applied in various real samples owing to the strong masking ability of EDTA. The assay was used to detect the concentrations of Cr3+ in liquid milk, milk power, and lake water samples with recoveries ranging from 93.5 to 114 %, indicating that the method could be used for extensive practical application.

Spectral data of specular reflectance, narrow-angle transmittance and angle-resolved surface scattering of materials for solar concentrators.

PubMed

Good, Philipp; Cooper, Thomas; Querci, Marco; Wiik, Nicolay; Ambrosetti, Gianluca; Steinfeld, Aldo

2016-03-01

The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of semi-transparent materials for solar collector covers at incidence angles 0-60°. In addition, the angle-resolved surface scattering of reflective materials is recorded by an area-scan CCD detector over the spectral range 350-1050 nm. A comprehensive summary, discussion, and interpretation of the results are included in the associated research article "Spectral reflectance, transmittance, and angular scattering of materials for solar concentrators" in Solar Energy Materials and Solar Cells.

Occurrence of nitrous oxide in the central High Plains aquifer, 1999

USGS Publications Warehouse

McMahon, P.B.; Bruch, B.W.; Becker, M.F.; Pope, L.M.; Dennehy, K.F.

2000-01-01

Nitrogen-enriched groundwater has been proposed as an important anthropogenic source of atmospheric nitrous oxide (N2O), yet few measurements of N2O in large aquifer systems have been made. Concentrations of N2O in water samples collected from the 124 000 km2 central High Plains aquifer in 1999 ranged from < 1 to 940 nM, with a median concentration of 29 nM (n = 123). Eighty percent of the N20 concentrations exceeded the aqueous concentration expected from equilibration with atmospheric N2O. Measurements of N2O, NO3-, and 3H in unsaturated-zone sediments, recently recharged groundwater, and older groundwater indicate that concentrations of N2O in groundwater increased over time and will likely continue to increase in the future as N-enriched water recharges the aquifer. Large concentrations of O2 and NO3- and small concentrations of NH4+ and dissolved organic carbon in the aquifer indicate that N2O in the central High Plains aquifer was produced primarily by nitrification. Calculations indicate that the flux of N2O from the central High Plains aquifer to the atmosphere from well pumping and groundwater discharge to streams was not a significant source of atmospheric N2O.Nitrogen-enriched groundwater has been proposed as an important anthropogenic source of atmospheric nitrous oxide (N2O), yet few measurements of N2O in large aquifer systems have been made. Concentrations of N2O in water samples collected from the 124000 km2 central High Plains aquifer in 1999 ranged from < 1 to 940 nM, with a median concentration of 29 nM (n = 123). Eighty percent of the N2O concentrations exceeded the aqueous concentration expected from equilibration with atmospheric N2O. Measurements of N2O, NO3-, and 3H in unsaturated-zone sediments, recently recharged groundwater, and older groundwater indicate that concentrations of N2O in groundwater increased over time and will likely continue to increase in the future as N-enriched water recharges the aquifer. Large concentrations of O2 and NO3- and small concentrations of NH4+ and dissolved organic carbon in the aquifer indicate that N2O in the central High Plains aquifer was produced primarily by nitrification. Calculations indicate that the flux of N2O from the central High Plains aquifer to the atmosphere from well pumping and groundwater discharge to streams was not a significant source of atmospheric N2O.Water samples were collected from 92 domestic wells, 16 monitoring wells and 15 public-supply wells in the High Plains Aquifer in 1999, and concentrations of nitrous oxide were measured. The groundwater concentrations ranged from less than 1 to 940 nM. Concentrations expressed as a percent of saturation in water ranged from less than 10 to 9690%. A significant decrease was noted in N2O concentrations with increasing depth of the well screen below the water table, and a significant positive correlation was found between the concentrations of N2O and nitrate. The small area-averaged N2O emission rate for the aquifer indicated that it was not an important component of the atmospheric N2O budget, but the importance could increase as groundwater N2O concentrations increase.

Analysis of major air pollutants and submicron particles in New York City and Long Island

NASA Astrophysics Data System (ADS)

Masiol, M.; Hopke, P. K.; Felton, H. D.; Frank, B. P.; Rattigan, O. V.; Wurth, M. J.; LaDuke, G. H.

2017-01-01

A year-long sampling campaign of major air pollutants and submicron particle number size distributions was conducted at two sites taken as representative of city-wide air quality in New York City and Long Island, respectively. A number of species were quantified with hourly time resolution, including particle number concentrations in 6 size ranges (20-30 nm, 30-50 nm, 50-70 nm, 70-100 nm, 100-200 nm, and >200 nm), nitrogen oxides, sulfur dioxide, ozone, carbon monoxide, methane, non-methane hydrocarbons, PM2.5 mass concentration and some PM major components (sulfate, organic and elemental carbon). Hourly concentrations of primary and secondary organic carbon were estimated using the EC tracer method. Data were matched with weather parameters and air parcel back-trajectories. A series of tools were thus applied to: (i) study the seasonal, weekly, diurnal cycles of pollutants; (ii) investigate the relationships amongst pollutants through correlation and lagged correlation analyses; (iii) depict the role of atmospheric photochemical processes; (iv) examine the location of the potential sources by mean of conditional bivariate probability function analysis and (v) investigate the role of regional transport of air masses to the concentrations of analyzed species. Results indicate that concentrations of NOx, SO2, CO, non-methane hydrocarbons, primary OC and EC are predominantly determined by local sources, but are also affected by regional transports of polluted air masses. On the contrary, the transport of continental polluted air masses has a main effect in raising the concentrations of secondary PM2.5 (sulfate and secondary organic carbon). By providing direct information on the concentrations and trends of key pollutants and submicron particle number concentrations, this study finally enables some general considerations about air quality status and atmospheric processes over the New York City metropolitan area.

Ultra-high sensitive substrates for surface enhanced Raman scattering, made of 3 nm gold nanoparticles embedded on SiO2 nanospheres

NASA Astrophysics Data System (ADS)

Phatangare, A. B.; Dhole, S. D.; Dahiwale, S. S.; Bhoraskar, V. N.

2018-05-01

The surface properties of substrates made of 3 nm gold nanoparticles embedded on SiO2 nanospheres enabled fingerprint detection of thiabendazole (TBZ), crystal violet (CV) and 4-Aminothiophenol (4-ATP) at an ultralow concentration of ∼10-18 M by surface enhanced Raman spectroscopy (SERS). Gold nanoparticles of an average size of ∼3 nm were synthesized and simultaneously embedded on SiO2 nanospheres by the electron irradiation method. The substrates made from the 3 nm gold nanoparticles embedded on SiO2 nanospheres were successfully used for recording fingerprint SERS spectra of TBZ, CV and 4-ATP over a wide range of concentrations from 10-6 M to 10-18 M using 785 nm laser. The unique features of these substrates are roughness near the surface due to the inherent structural defects of 3 nm gold nanoparticles, nanogaps of ≤ 1 nm between the embedded nanoparticles and their high number. These produced an abundance of nanocavities which act as active centers of hot-spots and provided a high electric field at the reporter molecules and thus an enhancement factor required to record the SERS spectra at ultra low concentration of 10-18 M. The SERS spectra recorded by the substrates of 4 nm and 6 nm gold nanoparticles are discussed.

Emission and distribution of PCDD/Fs, chlorobenzenes, chlorophenols, and PAHs from stack gas of a fluidized bed and a stoker waste incinerator in China.

PubMed

Wang, Tianjiao; Chen, Tong; Lin, Xiaoqing; Zhan, Mingxiu; Li, Xiaodong

2017-02-01

The concentrations, homologue, and congener profiles, as well as the gas/particle distribution of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), chlorobenzenes (CBzs), chlorophenols (CPhs), and polyaromatic hydrocarbons (PAHs) from stack gas of two different municipal solid waste incinerators in China, were characterized. The incinerators were a stoker furnace incinerator equipped with the advanced air pollution control device (APCD) and a common circulating fluidized bed (CFB) furnace. The concentration of PCDD/Fs in the stack gas of the stoker incinerator ranged 0.011-0.109 ng international toxic equivalent factor (I-TEQ)/Nm 3 and was below the current limit for PCDD/F emissions from the municipal solid waste incinerators (MSWIs) in China (0.1 ng I-TEQ/Nm 3 ) in most of the cases. Moreover, the concentration of PCDD/Fs in the stack gas of the stoker incinerator was significantly lower than that of the CFB incinerator (0.734 to 24.6 ng I-TEQ/Nm 3 ). In both incinerators, the majority of the total PCDD/F emissions (above 90%) ended up in the gas phase. 2,3,4,7,8-PeCDF, which occupied 24.3-43.6 and 32.5-75.6% of I-TEQ contribution in MSWIs A and B, respectively, was the most abundant congener. However, different types of incinerators and APCDs induced different congener and homologue distributions. The total concentration of CBzs from the stoker incinerator (0.05-3.2 μg/Nm 3 ) was also much lower than that formed from the CFB incinerator (10.9-75.2 μg/Nm 3 ). The phase distribution of CBzs followed the same pattern as with the PCDD/Fs. Moreover, the emission level of CBz was 100-1000 times higher than that of the PCDD/Fs, which determines the applicability of CBzs as indicators of PCDD/F emissions. High correlations between the emission concentrations of PCDD/Fs, TeCBz, and PCBz in specific ranges were revealed. Furthermore, high concentrations of CPhs (0.6-141.0 μg/Nm 3 ) and PAHs (148.6-4986.5 μg/Nm 3 ) were detected in the stack gases of MSWI B. In some cases, the concentrations were as high as the concentrations in the fumes exiting the boiler of one foreign stoker without flue gas purification indicating the abundance of CPh and PAH emissions in the stack gas of waste incinerators.

Characterisation of particle emissions from the driving car fleet and the contribution to ambient and indoor particle concentrations

NASA Astrophysics Data System (ADS)

Palmgren, Finn; Wåhlin, Peter; Kildesø, Jan; Afshari, Alireza; Fogh, Christian L.

The population is mainly exposed to high air pollution concentrations in the urban environment, where motor vehicle emissions constitute the main source of fine and ultrafine particles. These particles can penetrate deep into the respiratory system, and studies indicate that the smaller the particle, the larger the health impacts. The chemical composition, surface reactivity and physical properties are also important. However, the knowledge about chemical and physical properties of particles and the temporal and spatial variability of the smallest particles is still very limited. The present study summarises the first results of a larger project with the aims to improve the knowledge. The concentration and the emissions of ultrafine particles from petrol and diesel vehicles, respectively, have been quantified using Scanning Mobility Particle Sizer of ultrafine particles in the size range 6-700 nm and routine monitoring data from urban streets and urban background in Denmark. The quantification was carried out using receptor modelling. The number size distributions of petrol and diesel emissions showed a maximum at 20-30 nm and non-traffic at ≈100 nm. The contribution of ultrafine particles from diesel vehicles is dominating in streets. The same technique has been applied on PM 10, and ≈50% contribution from non-traffic. The technique has also been introduced in relation to elemental and organic carbon, and the first data showed strong correlation between traffic pollution and elemental carbon. The outdoor air quality has a significant effect on indoor pollution levels, and we spend most of the time indoors. Knowledge about the influence of ambient air pollution on the concentrations in the indoor environment is therefore crucial for assessment of human health effects of traffic pollution. The results of our studies will be included in air quality models for calculation of human exposure. Preliminary results from our first campaign showed, that the deposition rate of particles in the apartment is negligible in the particle size range 100-500 nm. In the size range below 100 nm the deposition rate increases with decreasing particle diameter to a value of approximately 1 h -1 at 10 nm. The penetration efficiency shows a maximum of 60% at 100 nm. More detailed studies of exchange of particles in outdoor/indoor air and the transformation are planned to take place during three next campaigns.

POP emissions from a large sinter plant in Taranto (Italy) over a five-year period following enforcement of new legislation.

PubMed

Esposito, Vittorio; Maffei, Annamaria; Bruno, Donato; Varvaglione, Berenice; Ficocelli, Salvatore; Capoccia, Carmelo; Spartera, Maria; Giua, Roberto; Blonda, Massimo; Assennato, Giorgio

2014-09-01

PCDD/F in exhaust gas emission samples was determined by the Environmental Agency of Apulia for a sinter plant located in Taranto (Italy) starting from June 2007 following an Agreement Act between plant owners and the Regional Government with the aim to assess and improve the environmental performances of the plant. The first two sampling campaigns yielded results ranging between 3.42 and 8.34 ng I-TE/Nm(3) that were soon considered revelatory of a high potential impact on the surrounding environment and the public, prompting for immediate action. As a first outcome, a Regional Regulation (LR 44/2008) was enforced in order to reduce PCDD/F emissions by plants operating in the metal sector, including sinter plants. After installation of a urea addition plant to the sinter mix as a process-integrated abatement technique the emissions ranged from 0.86 to 3.59 ng I-TE/Nm(3). In order to reach compliance to the newly introduced emission limit value of 0.4 ng I-TE/Nm(3) the urea plant was removed in favour of active-carbon injection as an end-of-pipe technique. Subsequently, during year 2011 emission values ranged from 0.095 to 1.97 ng I-TE/Nm(3), while in 2012 the observed range was 0.058 to 0.91 ng I-TE/Nm(3). As a better evaluation of the potential impact of the sinter plant emissions, a yearly mass-flow was estimated using exhaust gas PCDD/F concentrations and plant operational parameters (3.4 M Nm(3)/h). Mass-flow was estimated to be as high as 165 g I-TE/year for 2007 using yearly average concentrations or 248 g I-TE/year using the peak-value of 8.34 ng I-TE/Nm(3). Copyright © 2014 Elsevier B.V. All rights reserved.

Changes in hemodynamics and light scattering during cortical spreading depression

NASA Astrophysics Data System (ADS)

Li, Pengcheng; Yang, Yuanyuan; Luo, Qingming

2005-01-01

Cortical spreading depression (CSD) has been known to play an important role in the mechanism of migraine, stroke and brain injure. Optical imaging of intrinsic signals has been shown a powerful method for characterizing the spatial and temporal pattern of the propagation of CSD. However, the possible physiological mechanisms underlying the intrinsic optical signal (IOS) during CSD still remain incompletely understood. In this study, a spectroscopic recording of the change in optical intrinsic signal during CSD was performed and an analysis method based on the modified Beer-Lambert law was used to estimate the changes in the concentration of HbO2 and Hb, and changes in light scattering from the spectra data. The CSD were induced by pinprick in 10 α-chloralose/urethane anesthetized Sprague-Dawley rats. In all experiments, four-phasic changes in optical reflectance were observed at 450 nm ~ 570 nm, and triphasic changes in optical reflectance were observed in the range of 570 nm ~750 nm. But at 750 nm ~ 850 nm, only biphasic changes of optical signal were detected. Converting the spectra data to the changes in light scattering and concentration of Hb and HbO2, we found that the CSD induced an initial increase in concentration of HbO2 (amplitude: 9.0+/-3.7%), which was 26.2+/-18.6 s earlier than the onset of increase of Hb concentration. Furthermore, the concentration of HbO2 showed a four-phasic change, whereas the concentration of Hb only showed a biphasic change. For the changes in light scattering during CSD, a triphasic change was observed.

Complex analysis of concentrated antibody-gold nanoparticle conjugates' mixtures using asymmetric flow field-flow fractionation.

PubMed

Safenkova, Irina V; Slutskaya, Elvira S; Panferov, Vasily G; Zherdev, Anatoly V; Dzantiev, Boris B

2016-12-16

Conjugates of gold nanoparticles (GNPs) with antibodies are powerful analytical tools. It is crucial to know the conjugates' state in both the concentrated and mixed solutions used in analytical systems. Herein, we have applied asymmetrical flow field-flow fractionation (AF4) to identify the conjugates' state. The influence of a conjugate's composition and concentration on aggregation was studied in a true analytical solution (a concentrated mixture with stabilizing components). GNPs with an average diameter of 15.3±1.2nm were conjugated by adsorption with eight antibodies of different specificities. We found that, while the GNPs have a zeta potential of -31.6mV, the conjugates have zeta potentials ranging from -5.8 to -11.2mV. Increased concentrations (up to 184nM, OD 520 =80) of the mixed conjugate (mixture of eight conjugates) did not change the form of fractograms, and the peak areas' dependence on concentration was strongly linear (R 2 values of 0.99919 and 0.99845 for absorption signal and light scattering, respectively). Based on the gyration (R g ) and hydrodynamic (R h ) radii measured during fractionation, we found that the nanoparticles were divided into two populations: (1) those with constant radii (R g =9.9±0.9nm; R h =14.3±0.5nm); and (2) those with increased radii from 9.9 to 24.4nm for R g and from 14.3 to 28.1nm for R h . These results confirm that the aggregate state of the concentrated and mixed conjugates' preparations is the same as that of diluted preparations and that AF4 efficiently characterizes the conjugates' state in a true analytical solution. Copyright © 2016 Elsevier B.V. All rights reserved.

Measuring Aptamer Equilbria Using Gradient Micro Free Flow Electrophoresis

PubMed Central

Turgeon, Ryan T.; Fonslow, Bryan R.; Jing, Meng; Bowser, Michael T.

2010-01-01

Gradient micro free flow electrophoresis (μFFE) was used to observe the equilibria of DNA aptamers with their targets (IgE or HIVRT) across a range of ligand concentrations. A continuous stream of aptamer was mixed online with an increasing concentration of target and introduced into the μFFE device, which separated ligand-aptamer complexes from the unbound aptamer. The continuous nature of μFFE allowed the equilibrium distribution of aptamer and complex to be measured at 300 discrete target concentrations within 5 minutes. This is a significant improvement in speed and precision over affinity capillary electrophoresis (ACE) assays. The dissociation constant of the aptamer-IgE complex was estimated to be 48± 3 nM. The high coverage across the range of ligand concentrations allowed complex stoichiometries of the aptamer-HIVRT complexes to be observed. Nearly continuous observation of the equilibrium distribution from 0 to 500 nM HIVRT revealed the presence of complexes with 3:1 (aptamer:HIVRT), 2:1 and 1:1 stoichiometries. PMID:20373790

Physicochemical Characterization of Simulated Welding Fume from a Spark Discharge System

PubMed Central

Park, Jae Hong; Mudunkotuwa, Imali A.; Kim, Jong Sung; Stanam, Aditya; Thorne, Peter S.; Grassian, Vicki H.; Peters, Thomas M.

2014-01-01

This study introduces spark discharge system (SDS) as a way to simulate welding fumes. The SDS was developed using welding rods as electrodes with an optional coagulation chamber. The size, morphology, composition, and concentration of the fume produced and the concentration of ozone (O3) and nitrogen oxides (NOX) were characterized. The number median diameter (NMD) and total number concentration (TNC) of fresh fume particles were ranged 10–23 nm and 3.1×107–6×107 particles/cm3, respectively. For fresh fume particles, the total mass concentration (TMC) measured gravimetrically ranged 85–760 μg/m3. The size distribution was stable over a period of 12 h. The NMD and TNC of aged fume particles were ranged 81–154 nm and 1.5×106–2.7×106 particles/cm3, respectively. The composition of the aged fume particles was dominated by Fe and O with an estimated stoichiometry between that of Fe2O3 and Fe3O4. Concentrations of O3 and NOX were ranged 0.07–2.2 ppm and 1–20 ppm, respectively. These results indicate that the SDS is capable of producing stable fumes over a long-period that are similar to actual welding fumes. This system may be useful in toxicological studies and evaluation of instrumentation. PMID:25097299

Ozone Measurements with the US EPA UV-DIAL: Preliminary Results

NASA Technical Reports Server (NTRS)

Moosmueller, H.; Diebel, D.; Bundy, D. H.; Bristow, M. P.; Alvarez, R. J., II; Kovalev, V. A.; Edmonds, C. M.; Turner, R. M.; Mcelroy, J. L.

1992-01-01

A compact airborne down-looking lidar system was developed at the Environmental Protection Agency in Las Vegas. This differential absorption lidar (DIAL) was designed to simultaneously measure range-resolved concentrations of ozone (O3) and sulfur dioxide (SO2) in the lower troposphere, together with an indication of the aerosol distribution. The five laser wavelengths (i.e., lambda(sub 1) = 277 nm, lambda(sub 2) = 292 nm, lambda(sub 3) = 313 nm, lambda(sub4) = 319 nm, lambda(sub 5) = 369 nm) were generated via Raman conversion of a focused KrF excimer laser. The system is currently installed in a truck-based mobile laboratory. For the ground testing, an opening in the truck floor together with a folding mirror under the truck makes a horizontal, or upwardly inclined direction of measurement possible. Initial ground testing has been performed in the vicinity of a Desert Research Institute (DRI) ambient air monitoring site, located at Cottonwood Cove approximately 85 km south east of Las Vegas, Nevada. At this site O3 and SO2 concentrations are continuously monitored with an average accuracy better than +/- 10 percent. A temporary ozone measurement station with identical accuracy was set up at a distance to get a second point of comparison for the range-resolved DIAL measurements.

Linking CDOM spectral absorption to dissolved organic carbon concentrations and loadings in boreal estuaries

NASA Astrophysics Data System (ADS)

Asmala, Eero; Stedmon, Colin A.; Thomas, David N.

2012-10-01

The quantity of chromophoric dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in three Finnish estuaries (Karjaanjoki, Kyrönjoki and Kiiminkijoki) was investigated, with respect to predicting DOC concentrations and loadings from spectral CDOM absorption measurements. Altogether 87 samples were collected from three estuarine transects which were studied in three seasons, covering a salinity range between 0 and 6.8, and DOC concentrations from 1572 μmol l-1 in freshwater to 222 μmol l-1 in coastal waters. CDOM absorption coefficient, aCDOM(375) values followed the trend in DOC concentrations across the salinity gradient and ranged from 1.67 to 33.4 m-1. The link between DOC and CDOM was studied using a range of wavelengths and algorithms. Wavelengths between 250 and 270 nm gave the best predictions with single linear regression. Total dissolved iron was found to influence the prediction in wavelengths above 520 nm. Despite significant seasonal and spatial differences in DOC-CDOM models, a universal relationship was tested with an independent data set and found to be robust. DOC and CDOM yields (loading/catchment area) from the catchments ranged from 1.98 to 5.44 g C m-2 yr-1, and 1.67 to 11.5 aCDOM(375) yr-1, respectively.

Inhibition of Voltage-Gated Calcium Channels as Common Mode of Action for (Mixtures of) Distinct Classes of Insecticides

PubMed Central

Meijer, Marieke; Dingemans, Milou M.L.; van den Berg, Martin; Westerink, Remco H.S.

2014-01-01

Humans are exposed to distinct structural classes of insecticides with different neurotoxic modes of action. Because calcium homeostasis is essential for proper neuronal function and development, we investigated the effects of insecticides from different classes (pyrethroid: (α-)cypermethrin; organophosphate: chlorpyrifos; organochlorine: endosulfan; neonicotinoid: imidacloprid) and mixtures thereof on the intracellular calcium concentration ([Ca2+]i). Effects of acute (20 min) exposure to (mixtures of) insecticides on basal and depolarization-evoked [Ca2+]i were studied in vitro with Fura-2-loaded PC12 cells and high resolution single-cell fluorescence microscopy. The data demonstrate that cypermethrin, α-cypermethrin, endosulfan, and chlorpyrifos concentration-dependently decreased depolarization-evoked [Ca2+]i, with 50% (IC50) at 78nM, 239nM, 250nM, and 899nM, respectively. Additionally, acute exposure to chlorpyrifos or endosulfan (10μM) induced a modest increase in basal [Ca2+]i, amounting to 68 ± 8nM and 53 ± 8nM, respectively. Imidacloprid did not disturb basal or depolarization-evoked [Ca2+]i at 10μM. Following exposure to binary mixtures, effects on depolarization-evoked [Ca2+]i were within the expected effect additivity range, whereas the effect of the tertiary mixture was less than this expected additivity effect range. These results demonstrate that different types of insecticides inhibit depolarization-evoked [Ca2+]i in PC12 cells by inhibiting voltage-gated calcium channels (VGCCs) in vitro at concentrations comparable with human occupational exposure levels. Moreover, the effective concentrations in this study are below those for earlier described modes of action. Because inhibition of VGCCs appears to be a common and potentially additive mode of action of several classes of insecticides, this target should be considered in neurotoxicity risk assessment studies. PMID:24913802

Direct and quantitative AFM measurements of the concentration and temperature dependence of the hydrophobic force law at nanoscopic contacts.

PubMed

Stock, Philipp; Utzig, Thomas; Valtiner, Markus

2015-05-15

By virtue of its importance for self-organization of biological matter the hydrophobic force law and the range of hydrophobic interactions (HI) have been debated extensively over the last 40 years. Here, we directly measure and quantify the hydrophobic force-distance law over large temperature and concentration ranges. In particular, we study the HI between molecularly smooth hydrophobic self-assembled monolayers, and similarly modified gold-coated AFM tips (radii∼8-50 nm). We present quantitative and direct evidence that the hydrophobic force is both long-ranged and exponential down to distances of about 1-2 nm. Therefore, we introduce a self-consistent radius-normalization for atomic force microscopy data. This approach allows quantitative data fitting of AFM-based experimental data to the recently proposed Hydra-model. With a statistical significance of r(2)⩾0.96 our fitting and data directly reveal an exponential HI decay length of 7.2±1.2 Å that is independent of the salt concentration up to 750 mM. As such, electrostatic screening does not have a significant influence on the HI in electrolyte concentrations ranging from 1 mM to 750 mM. In 1 M solutions the observed instability during approach shifts to longer distances, indicating ion correlation/adsorption effects at high salt concentrations. With increasing temperature the magnitude of HI decreases monotonically, while the range increases slightly. We compare our results to the large body of available literature, and shed new light into range and magnitude of hydrophobic interactions at very close distances and over wide temperature and concentration regimes. Copyright © 2015 Elsevier Inc. All rights reserved.

New simple spectrophotometric method for determination of the binary mixtures (atorvastatin calcium and ezetimibe; candesartan cilexetil and hydrochlorothiazide) in tablets.

PubMed

Belal, Tarek S; Daabees, Hoda G; Abdel-Khalek, Magdi M; Mahrous, Mohamed S; Khamis, Mona M

2013-04-01

A new simple spectrophotometric method was developed for the determination of binary mixtures without prior separation. The method is based on the generation of ratio spectra of compound X by using a standard spectrum of compound Y as a divisor. The peak to trough amplitudes between two selected wavelengths in the ratio spectra are proportional to concentration of X without interference from Y . The method was demonstrated by determination of two drug combinations. The first consists of the two antihyperlipidemics: atorvastatin calcium (ATV) and ezetimibe (EZE), and the second comprises the antihypertensives: candesartan cilexetil (CAN) and hydrochlorothiazide (HCT). For mixture 1, ATV was determined using 10 μg/mL EZE as the divisor to generate the ratio spectra, and the peak to trough amplitudes between 231 and 276 nm were plotted against ATV concentration. Similarly, by using 10 μg/mL ATV as divisor, the peak to trough amplitudes between 231 and 276 nm were found proportional to EZE concentration. Calibration curves were linear in the range 2.5-40 μg/mL for both drugs. For mixture 2, divisor concentration was 7.5 μg/mL for both drugs. CAN was determined using its peak to trough amplitudes at 251 and 277 nm, while HCT was estimated using the amplitudes between 251 and 276 nm. The measured amplitudes were linearly correlated to concentration in the ranges 2.5-50 and 1-30 μg/mL for CAN and HCT, respectively. The proposed spectrophotometric method was validated and successfully applied for the assay of both drug combinations in several laboratory-prepared mixtures and commercial tablets.

New simple spectrophotometric method for determination of the binary mixtures (atorvastatin calcium and ezetimibe; candesartan cilexetil and hydrochlorothiazide) in tablets

PubMed Central

Belal, Tarek S.; Daabees, Hoda G.; Abdel-Khalek, Magdi M.; Mahrous, Mohamed S.; Khamis, Mona M.

2012-01-01

A new simple spectrophotometric method was developed for the determination of binary mixtures without prior separation. The method is based on the generation of ratio spectra of compound X by using a standard spectrum of compound Y as a divisor. The peak to trough amplitudes between two selected wavelengths in the ratio spectra are proportional to concentration of X without interference from Y. The method was demonstrated by determination of two drug combinations. The first consists of the two antihyperlipidemics: atorvastatin calcium (ATV) and ezetimibe (EZE), and the second comprises the antihypertensives: candesartan cilexetil (CAN) and hydrochlorothiazide (HCT). For mixture 1, ATV was determined using 10 μg/mL EZE as the divisor to generate the ratio spectra, and the peak to trough amplitudes between 231 and 276 nm were plotted against ATV concentration. Similarly, by using 10 μg/mL ATV as divisor, the peak to trough amplitudes between 231 and 276 nm were found proportional to EZE concentration. Calibration curves were linear in the range 2.5–40 μg/mL for both drugs. For mixture 2, divisor concentration was 7.5 μg/mL for both drugs. CAN was determined using its peak to trough amplitudes at 251 and 277 nm, while HCT was estimated using the amplitudes between 251 and 276 nm. The measured amplitudes were linearly correlated to concentration in the ranges 2.5–50 and 1–30 μg/mL for CAN and HCT, respectively. The proposed spectrophotometric method was validated and successfully applied for the assay of both drug combinations in several laboratory-prepared mixtures and commercial tablets. PMID:29403805

Photoconductivity of Macroporous and Nonporous Silicon with Ultrathin Oxide Layers

NASA Astrophysics Data System (ADS)

Konin, K. P.; Goltvyansky, Yu. V.; Karachevtseva, L. A.; Karas, M. I.; Morozovs'ka, D. V.

2018-06-01

The photoconductivity of macroporous silicon with ultrathin oxide layers of 2.7-30 nm in thickness at short-wave optical excitation was studied. The following feature was revealed: a nonmonotonic change in the photoconductivity as a function of the oxide thickness. At a minimum thickness, the photoconductivity is negative; in the interval 6.8-15 nm, it is very much suppressed; at 15-30 nm, it is positive. Suppression of photoconductivity over a wide thickness range indicates an abnormally high concentration of traps and capture centers for charge carriers of both signs. Such a change in the photoconductivity corresponds to the known results on the continuous morphological rearrangement of the oxide in the thickness range from 6-7 nm to 12-15 nm from the coesite-like (4-membered SiO4 tetrahedra rings) to the tridymite-like (6-membered SiO4 tetrahedra rings). The suppression of photoconductivity in the intermediate range probably demonstrates the collective, antisynergetic action of these coexisting oxide forms on the nonequilibrium charge carriers. These coexisting oxide forms manifest themselves as an unusual collective defect.

Power and efficiency scaling of diode pumped Cr:LiSAF lasers: 770-1110 nm tuning range and frequency doubling to 387-463 nm.

PubMed

Demirbas, Umit; Baali, Ilyes

2015-10-15

We report significant average power and efficiency scaling of diode-pumped Cr:LiSAF lasers in continuous-wave (cw), cw frequency-doubled, and mode-locked regimes. Four single-emitter broad-area laser diodes around 660 nm were used as the pump source, which provided a total pump power of 7.2 W. To minimize thermal effects, a 20 mm long Cr:LiSAF sample with a relatively low Cr-concentration (0.8%) was used as the gain medium. In cw laser experiments, 2.4 W of output power, a slope efficiency of 50%, and a tuning range covering the 770-1110 nm region were achieved. Intracavity frequency doubling with beta-barium borate (BBO) crystals generated up to 1160 mW of blue power and a record tuning range in the 387-463 nm region. When mode locked with a saturable absorber mirror, the laser produced 195 fs pulses with 580 mW of average power around 820 nm at a 100.3 MHz repetition rate. The optical-to-optical conversion efficiency of the system was 33% in cw, 16% in cw frequency-doubled, and 8% in cw mode-locked regimes.

Measuring free metal ion concentrations in situ in natural waters using the Donnan Membrane Technique.

PubMed

Kalis, Erwin J J; Weng, Liping; Dousma, Freerk; Temminghoff, Erwin J M; Van Riemsdijk, Willem H

2006-02-01

Metal toxicity is not related to the total but rather to the free or labile metal ion concentration. One of the techniques that can be used to measure several free metal ion concentrations simultaneously is the Donnan Membrane Technique (DMT) in combination with the inductively coupled plasma-mass spectrometer (ICP-MS). However, free metal ion concentrations in natural waters are commonly below the detection limit of ICP-MS. We decreased the detection limit by making use of a ligand, and we developed a field DMT cell that can be applied in situ in natural waters. A kinetic approach can be used to calculate free metal ion concentrations when the equilibrium time becomes too large. The field DMT measured in situ in natural waters a free metal ion concentration ranging from 0.015% (Cu) to 13% (Zn) of a total metal concentration ranging from 0.06 nM (Cd) to 237 nM (Zn). The free metal ion concentrations were difficult to predict using an equilibrium speciation model, probably due to the uncertainty in the nature of the dissolved organic matter or the presence of other reactive colloids. It is shown that DMT can follow changes in the free metal ion concentration on times scales less than a day under certain conditions.

Spectrophotometric and HPLC Methods for Simultaneous Estimation of Amlodipine Besilate, Losartan Potassium and Hydrochlorothiazide in Tablets

PubMed Central

Wankhede, S. B.; Raka, K. C.; Wadkar, S. B.; Chitlange, S. S.

2010-01-01

Two UV-spectrophotometric and one reverse phase high performance liquid chromatography methods have been developed for the simultaneous estimation of amlodipine besilate, losartan potassium and hydrochlorothiazide in tablet dosage form. The first UV spectrophotometric method was a determination using the simultaneous equation method at 236.5, 254 and 271 nm over the concentration range 5-25, 10-50 and 5-25 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. The second UV method was a determination using the area under curve method at 231.5-241.5, 249-259 and 266-276 nm over the concentration range of 5-25, 5-25 and 10-50 μg/ml for amlodipine besilate, hydrochlorothiazide and losartan potassium, respectively. In reverse phase high performance liquid chromatography analysis is carried out using 0.025 M phosphate buffer (pH 3.7):acetonitrile (57:43 v/v) as the mobile phase and Kromasil C18 (4.6 mm i.d×250 mm) column as stationery phase with detection wavelength of 232 nm linearity was obtained in the concentration range of 2-14, 20-140 and 5-40 μg/ml for amlodipine besilate, losartan potassium and hydrochlorothiazide, respectively. Both UV-spectrophotometric and reverse phase high performance liquid chromatography methods were statistically validated and can be used for analysis of combined dose tablet formulation containing amlodipine besilate, losartan potassium and hydrochlorothiazide. PMID:20582208

Influences of cholecystokinin octapeptide on phosphoinositide turnover in neonatal-rat brain cells.

PubMed Central

Zhang, L J; Lu, X Y; Han, J S

1992-01-01

Cholecystokinin octapeptide (CCK-8) has been shown to be coupled to phosphoinositide turnover in pancreatic acini as well as in a kind of neuroblastoma cell and a human embryonic cell line. Little is known, however, about its link with phosphatidylinositol breakdown in the brain. The brains (minus cerebella) from 1-2-day-old neonatal rats were enzymically dissociated into single cells. The intact cells were prelabelled by incubation with myo-[3H]inositol for 3 h, and were then stimulated with agonists in the presence of 10 mM-LiCl. Carbachol at 1 mM induced an increase in InsP3 labelling in brain cells (peak at 30 min, and then a gradual decrease), and a static accumulation of InsP with time, whereas the labelling of InsP2 remained essentially unchanged. A very similar time-response curve was obtained for 10 nM-CCK-8 in stimulating phosphoinositide turnover. The dose-response curve for incubated brain cells revealed that the formation of InsP3 increased when the concentration of CCK-8 was increased from 0.1 to 10 nM. A further increase in CCK-8 concentration to 100-1000 nM resulted in a gradual decrease in InsP3 formation. InsP and InsP2 levels stayed relatively stable. The production of InsP3 stimulated by 10 nM-CCK-8 was dose-dependently suppressed by the CCK-A antagonist Devazepide in the concentration range 1-10 nM; the effect declined when the concentration was further increased to 100-1000 nM. In contrast, the CCK-B antagonist L365,260 showed a sustained suppression of InsP3 production at concentrations above 0.1 nM, i.e. in the range 1-1000 nM. The results provide evidence that CCK-8 stimulates the turnover of phosphoinositide and increases InsP3 labelling in dissociated neonatal-rat brain cells, in which both CCK-A and CCK-B receptors seem to be involved. PMID:1323276

United role of radon decay products and nano-aerosols in radon dosimetry

NASA Astrophysics Data System (ADS)

Smerajec, M.; Vaupotič, J.

2012-04-01

The major part of human exposure to natural radiation originates from inhalation of radon (Rn) and radon short-lived decay products (RnDP: 218Po, 214Pb, 214Bi and 214Po). RnDP are formed as a result of α-transformation of radon. In the beginning they are positive ions which neutralize and form clusters with air molecules, and later partly attach to background aerosol particles in indoor air. Eventually, they appear as radioactive nano-aerosols with a bimodal size distribution in ranges of 1-10 nm (unattached RnDP) and of 200-800 nm (attached RnDP). When inhaled, they are deposited in the respiratory tract. Deposition is more efficient for smaller particles. Therefore, the fraction (fun) of the unattached RnDP, which appears to be influenced by the number concentration and size distribution of general (background) aerosols in the ambient air, has a crucial role in radon dosimetry. Radon, radon decay products and general aerosols have been monitored simultaneously in the kitchen of a typical rural house under real living conditions, also comprising four human activities generating particular matter: cooking and baking, as two typical activities in kitchen, and cigarette smoking and candle burning. In periods without any human activity, the total number concentration of general aerosol ranged from 1000 to 3000 cm-3,with the geometric mean of particle diameter in the range of 60-68 nm and with 0.1-1 % of particles smaller than 10 nm. Preparation of coffee changed the concentration to 193,000 cm-3, the geometric mean of diameter to 20 nm and fraction of particles smaller than 10 nm to 11 %. The respective changes were for baking cake: 503,000 cm-3, 17 nm and 19 %, for smoking:423,000 cm-3, 83 nm and 0.4 %, and forcandle burning: 945,000 cm-3, 8 nm and 85 %. While, as expected, a reduction of fun was observed during cooking, baking and smoking, when larger particles were emitted, fun did not increase during candle burning with mostly particles smaller than 10 nm produced. Because the processes of RnDP creation by radioactive transformation, their neutralization, clustering and association with aerosol particles need time, the response of fun on the changes in general aerosol is delayed in time and therefore fun response on the fast changes, such as those caused by short human activities, may be obscured and even not observed.

Donor-acceptor-pair emission in fluorescent 4H-SiC grown by PVT method

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

Liu, Xi, E-mail: liuxi@mail.sic.ac.cn; Zhuo, Shi-Yi; Gao, Pan

Fluorescent SiC, which contains donor and acceptor impurities with optimum concentrations, can work as a phosphor for visible light emission by donor-acceptor-pair (DAP) recombination. In this work, 3 inch N-B-Al co-doped fluorescent 4H-SiC crystals are prepared by PVT method. The p-type fluorescent 4H-SiC with low aluminum doping concentration can show intensive yellow-green fluorescence at room temperature. N-B DAP peak wavelength shifts from 578nm to 525nm and weak N-Al DAP emission occurred 403/420 nm quenches, when the temperature increases from 4K to 298K. The aluminum doping induces higher defect concentration in the fluorescent crystal and decreases optical transmissivity of the crystalmore » in the visible light range. It triggers more non-radiative recombination and light absorption losses in the crystal.« less

[Atmospheric particle formation events in Nanjing during summer 2010].

PubMed

Wang, Hong-Lei; Zhu, Bin; Shen, Li-Juan; Kang, Han-Qing; Diao, Yi-Wei

2012-03-01

Feature of aerosol particle number concentration, condition and impact factor of new particle formation (NPF) were investigated in Nanjing during summer. In this study, aerosol particle number concentration and gaseous pollutants (O3, SO2 and NO2) measurements were carried out by Wide-Range Particle Spectrometer (WPS) and Differential Optical Absorption Spectroscopy (DOAS) in July 2010. Combining with observations from Automatic Weather Station and Backward Trajectory Simulation, the condition and impact factor of NPF were discussed. Results showed that the averaged 10-500 nm particle number concentration was 1.7 x 10(4) cm(-3), similar to some typical observation values in North American and Europe; the 10-25 nm particle number concentration accounted for 25% of the total number concentration. Six NPF events occurred during observation. We analyzed that stable wind speed and direction, strong solar radiation promoted the NPF. The humidity during NPF event varied from 50% to 70%. Results indicated that clean ocean air mass brought from easterly and southerly wind promoted the NPF by Backward Trajectory Model Simulation. During the NPF event, the 10 - 25 nm particle number concentration positively correlated with the concentration of SO2, and negatively correlated with O3, whereas poorly correlated with NO2.

PM2.5 chemical composition at a rural background site in Central Europe, including correlation and air mass back trajectory analysis

NASA Astrophysics Data System (ADS)

Schwarz, Jaroslav; Cusack, Michael; Karban, Jindřich; Chalupníčková, Eva; Havránek, Vladimír; Smolík, Jiří; Ždímal, Vladimír

2016-07-01

PM2.5 mass concentrations and chemical compositions sampled over a 13-month period at a Central European rural background site (Košetice) are presented in this work. A comprehensive chemical analysis of PM2.5 was performed, which provided elemental composition (Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Y, Zr, and Pb) and the concentration of water-soluble inorganic anions (SO42 -, NO3-. Cl-, NO2-, Br-, and H2PO4-) and cations (Na+, NH4+, K+, Ca2 +, and Mg2 +), elemental and organic carbon (EC and OC), and levoglucosan. Spearman correlation coefficients between individual chemical species and particle number concentrations were calculated for the following six size ranges: 10-25 nm (N10-25), 25-50 nm (N25-50), 50-80 nm (N50-80), 80-150 nm (N80-150), 150-300 nm (N150-300), and 300-800 nm (N300-800). Average concentrations of individual species were comparable with concentrations reported from similar sites across Central Europe. Organic matter (OM) accounted for 45% of the PM2.5 mass (calculated from OC by a factor of 1.6), while the second most common component were secondary aerosols (SO42 -: 19%, NO3-: 14%, NH4+: 10%), which accounted for 43% of the mass. Based on levoglucosan analysis, 31% of OM was attributed to emissions associated with biomass burning (OMBB). EC concentrations, determined using the EUSAAR_2 thermal optical protocol, contributed 4% to PM2.5 mass. A total of 1% of the mass was attributed to a mineral matter source, while the remaining 6% was from an undetermined mass. Seasonal variations showed highest concentrations of NO3- and OMBB in winter, nitrate share in spring, and an increase in percentage of SO42 - and mineral matter in summer. The largest seasonal variation was found for species associated with wood and coal combustion (levoglucosan, K+, Zn, Pb, As), which had clear maxima during winter. Correlation analysis of different size fraction particle number concentrations was used to distinguish the influence of fresh, local aerosol and aged, long-range transport aerosol. The influences of different air masses were also investigated. The lowest concentrations of PM2.5 were recorded under the influence of marine air masses from the NW, which were also marked by increased concentrations of marine aerosol. In contrast, the highest concentrations of PM2.5 and most major chemical components were measured during periods when continental easterly air masses were dominant.

Water Raman normalization of airborne laser fluorosensor measurements - A computer model study

NASA Technical Reports Server (NTRS)

Poole, L. R.; Esaias, W. E.

1982-01-01

The technique for normalizing airborne lidar measurements of chlorophyll fluoresence by the water Raman scattering signal is investigated for laser-excitation wavelengths of 480 and 532 nm using a semianalytic Monte Carlo methodology (SALMON). The signal-integration depth for chlorophyll fluorescence Z(90,F), is found to be insensitive to excitation wavelength and ranges from a maximum of 4.5 m in clearest waters to less than 1 m at a chlorophyll concentration of 20 microgram/liter. For excitation at 532 nm, the signal-integration depth for Raman scattering, Z(90,R), is comparable to Z(90,F). For excitation at 480 nm, Z(90,R) is four times as large as Z(90,F) in clearest waters but nearly equivalent at chlorophyll concentrations greater than 2-3 microgram/liter. Absolute signal levels are stronger with excitation at 480 nm than with excitation at 532 nm, but this advantage must be weighed against potential ambiguities resulting from different integration depths for the fluorescence and Raman scattering signals in clearer waters. To the precision of the simulations, Raman normalization produces effectively linear response to chlorophyll concentration for both excitation wavelengths.

Temperature and salinity correction coefficients for light absorption by water in the visible to infrared spectral region.

PubMed

Röttgers, Rüdiger; McKee, David; Utschig, Christian

2014-10-20

The light absorption coefficient of water is dependent on temperature and concentration of ions, i.e. the salinity in seawater. Accurate knowledge of the water absorption coefficient, a, and/or its temperature and salinity correction coefficients, Ψ(T) and Ψ(S), respectively, is essential for a wide range of optical applications. Values are available from published data only at specific narrow wavelength ranges or at single wavelengths in the visible and infrared regions. Ψ(T) and Ψ(S) were therefore spectrophotometrically measured throughout the visible, near, and short wavelength infrared spectral region (400 to ~2700 nm). Additionally, they were derived from more precise measurements with a point-source integrating-cavity absorption meter (PSICAM) for 400 to 700 nm. When combined with earlier measurements from the literature in the range of 2600 - 14000 nm (wavenumber: 3800 - 700 cm(-1)), the coefficients are provided for 400 to 14000 nm (wavenumber: 25000 to 700 cm(-1)).

Derivative spectrophotometric method for simultaneous determination of clindamycin phosphate and tretinoin in pharmaceutical dosage forms.

PubMed

Barazandeh Tehrani, Maliheh; Namadchian, Melika; Fadaye Vatan, Sedigheh; Souri, Effat

2013-04-10

A derivative spectrophotometric method was proposed for the simultaneous determination of clindamycin and tretinoin in pharmaceutical dosage forms. The measurement was achieved using the first and second derivative signals of clindamycin at (1D) 251 nm and (2D) 239 nm and tretinoin at (1D) 364 nm and (2D) 387 nm.The proposed method showed excellent linearity at both first and second derivative order in the range of 60-1200 and 1.25-25 μg/ml for clindamycin phosphate and tretinoin respectively. The within-day and between-day precision and accuracy was in acceptable range (CV<3.81%, error<3.20%). Good agreement between the found andadded concentrations indicates successful application of the proposed method for simultaneous determination of clindamycin and tretinoin in synthetic mixtures and pharmaceutical dosage form.

Atmospheric CO2 measurements with a 2-μm DIAL instrument

NASA Astrophysics Data System (ADS)

Cadiou, Erwan; Dherbecourt*, Jean-Baptiste; Gorju, Guillaume; Melkonian, Jean-Michel; Godard, Antoine; Pelon, Jacques; Raybaut, Myriam

2018-04-01

We report on ground-based atmospheric concentration measurements of carbon dioxide, using a pulsed direct detection differential absorption lidar operating at 2051 nm. The transmitter is based on a tunable parametric source emitting 10-mJ energy, 10-ns duration Fourier-limited pulses. Range resolved concentration measurements have been carried out on the aerosol back-scattered signal. Cloud signals have been used to get long range integrated-path measurements.

LED-pumped Alexandrite laser oscillator and amplifier

NASA Astrophysics Data System (ADS)

Pichon, Pierre; Blanchot, Jean-Philippe; Balembois, François; Druon, Frédéric; Georges, Patrick

2018-02-01

In this paper, we report the first LED-pumped transition-metal-doped laser oscillator and amplifier based on an alexandrite crystal (Cr3+:BeAl2O4). A Ce:YAG luminescent concentrator illuminated by blue LEDs is used to reach higher pump powers than with LEDs alone. The luminescent 200-mm-long-composit luminescent concentrator involving 2240 LEDs can delivers up to 268 mJ for a peak irradiance of 8.5 kW/cm2. In oscillator configuration, an LED-pumped alexandrite laser delivering an energy of 2.9 mJ at 748 nm in free running operation is demonstrated. In the cavity, we measured a double pass small signal gain of 1.28, in good agreement with numerical simulations. As amplifier, the system demonstrated to boost a CW Ti:sapphire laser by a factor of 4 at 750 nm in 8 passes with a large tuning range from 710 nm to 800 nm.

Detection of low-concentration ammonia using differential laser-induced fluorescence on vapochromic coordination polymers

NASA Astrophysics Data System (ADS)

Yin, Dawei; Chapman, Glenn H.; Stevens, David; Gray, Bonnie; Leznoff, Daniel

2018-02-01

The detection of ammonia in parts per millions range has been challenging in sensors research, and is of great importance for industrial applications. In previous literature, Vapochromic Coordination Polymers (VCP) were developed to achieve luminescence upon a targeted gas exposures. We investigate a specific VCP, Zn[Au(CN)2]2,as an ammonia sensing material. Upon high concentration ammonia exposure, the fluorescent peak under near-UV stimulation undergoes a spectral shift from 460nm to 520nm, while the intensity increases by 3 4X. However, at ammonia concentrations < 50ppm, the spectral shift becomes hidden within the overall changing fluorescent spectrum shape. Then simple methods, such as detecting the peak wavelength or subtracting post-exposure from pre-exposure spectrums do not work. We developed further excitation and data processing techniques to detect ammonia at lower concentrations. A low-cost 405nm blue-ray DVD laser diode was used as the excitation source, providing a narrow band-width (4nm) stimulation that is separated from the emission peak. We measured the emission using a portable spectrometer (Photon Control SPM-002), and processed the data by separating the spectrum into two regions; (A) from 425 nm to 460 nm and (B) from 460nm to 500nm. Next, the integrated emissions under both regions were computed, and the value of shorter wavelength region (A) was subtracted from the longer wavelength one (B). When exposed to ammonia, region (A) reduces overall intensity while region (B) increases, resulting a signal starting from negative value and gradually increases to positive values, enabling the detection of 5ppm ammonia in less than 30 seconds gas exposure.

Spectrophotometric and spectrofluorimetric methods for determination of certain biologically active phenolic drugs in their bulk powders and different pharmaceutical formulations

NASA Astrophysics Data System (ADS)

Omar, Mahmoud A.; Badr El-Din, Kalid M.; Salem, Hesham; Abdelmageed, Osama H.

2018-03-01

Two simple and sensitive spectrophotometric and spectrofluorimetric methods for the determination of terbutaline sulfate, fenoterol hydrobromide, etilefrine hydrochloride, isoxsuprine hydrochloride, ethamsylate, doxycycline hyclate have been developed. Both methods were based on the oxidation of the cited drugs with cerium (IV) in acid medium. The spectrophotometric method was based on measurement of the absorbance difference (ΔA), which represents the excess cerium (IV), at 317 nm for each drug. On the other hand, the spectrofluorimetric method was based on measurement of the fluorescent of the produced cerium (III) at emission wavelength 354 nm (λexcitation = 255 nm) for the concentrations studied for each drug. For both methods, the variables affecting the reactions were carefully investigated and the conditions were optimized. Linear relationships were found between either ΔA or the fluorescent of the produced cerium (III) values and the concentration of the studied drugs in a general concentration range of 2.0-24.0 μg mL- 1, 20.0-24.0 ng mL- 1 with good correlation coefficients in the following range 0.9990-0.9999, 0.9990-0.9993 for spectrophotometric and spectrofluorimetric methods respectively. The limits of detection and quantitation of spectrophotometric method were found in general concentration range 0.190-0.787 and 0.634-2.624 μg mL- 1respectively. For spectrofluorimetric method, the limits of detection and quantitation were found in general concentration range 4.77-9.52 and 15.91-31.74 ng mL- 1 respectively. The stoichiometry of the reaction was determined, and the reactions pathways were postulated. The analytical performance of the methods, in terms of accuracy and precision, were statistically validated and the results obtained were satisfactory. The methods have been successfully applied to the determination of the cited drugs in their commercial pharmaceutical formulations. Statistical comparison of the results with the reference methods showed excellent agreement and proved that no significant difference in the accuracy and precision.

[Preparation and photoluminescence study of Er3+ : Y2O3 transparent ceramics].

PubMed

Luo, Jun-ming; Li, Yong-xiu; Deng, Li-ping

2008-10-01

Y2O3 acted as the matrix material, which was doped with different concentrations of Er3+, Er3+ : Y2O3 nanocrystalline powder was prepared by co-precipitation method, and Er3+ : Y2O3 transparent ceramics was fabricated by vacuum sintering at 1700 degrees C, 1 x 10(-3) Pa for 8 h. By using the X-ray diffraction (D/MAX-RB), transmission electron microscopy(Philips EM420), automatic logging spectrophotometer(DMR-22), fluorescence analyzer (F-4500) and 980 nm diode laser, the structural, morphological and luminescence properties of the sample were investigated. The results show that Er3+ dissolved completely in the Y2O3 cubic phase, the precursor was amorphous, weak diffraction peaks appeared after calcination at 400 degrees C, and if calcined at 700 degrees C, the precursor turned to pure cubic phase. With increasing the calcining temperature, the diffraction peaks became sharp quickly, and when the calcining temperature reached 1100 degrees C, the diffraction peaks became very sharp, indicating that the grains were very large. The particles of Er+ : Y2O3 is homogeneous and nearly spherical, the average diameter of the particles is in the range of 40-60 nm after being calcined at 1000 degrees C for 2 h. The relative density of Er3+ : Y2O3 transparent ceramics is 99.8%, the transmittance of the Er2+ : Y2O3 transparent ceramics is markedly lower than the single crystal at the short wavelength, but the transmittance is improved noticeably with increasing the wavelength, and the transmittance exceeds 60% at the wavelength of 1200 nm. Excited under the 980 nm diode laser, there are two main up-conversion emission bands, green emission centers at 562 nm and red emission centers at 660 nm, which correspond to (4)S(3/2) / (2)H(11/2) - (4)I(15/2) and (4)F(9/2) - (4)I(15/2) radiative transitions respectively. By changing the doping concentrations of Er3+, the color of up-conversion luminescence can be tuned from green to red gradually. The luminescence intensity is not reinforce with the increase in the concentration, so the doping concentration of Er3+ should not exceed 2%. If the doping concentration of Er3+ exceeds the range, the concentration has very small effect on the improvement of luminescence intensity.

Development of a fluorescence lidar for biological aerosol detection in the air

NASA Astrophysics Data System (ADS)

He, Tingyao; Rao, Zhimin

2017-10-01

In order to investigate biological aerosols in the air, a fluorescence lidar has being developed at Laser Radar Center of Remote Sensing of Atmosphere, Xi'an University of Technology. The fluorescence lidar is constructed with a pulsed Nd:YAG laser, employing at based harmonic (1064 nm), second harmonic (532 nm) and fourth harmonic (266 nm) simultaneously, with a repetition rate of 10 Hz. A 250 mm diameter custom telescope is used to collect optical spectra ranging from 260-1100 nm. In the Infrared detection, an avalanche diode (APD) is used, and two photomultiplier tubes (PMTs) for two linear orthogonal polarization detection at a wavelength of 532 nm. Range-resolved fluorescence signals are collected in 32 channels of compound PMT sensor coupled with Czerny-Turner spectrograph. Based on the current configurations, we performed a series of numerical simulations to estimate the maximal detectable ranges and the minimal detectable concentrations of biological aerosols with various conditions. With a relative error of less than 10%, simulated results show that the system is able to monitor biological aerosols within detected distances of 1.3 km and of 2.0 km at daytime and nighttime, respectively. The developing fluorescence lidar is also capable to identify a minimum concentration of bio-aerosols at about 150 particles;L-1 with daytime operation and 100 particles;L-1 with nighttime at a distance of about 0.1 km. We truly believe that the fluorescence lidar could be spread in the field of remote sensing of biological aerosols in the near future.

Two different spectrophotometric determinations of potential anticancer drug and its toxic metabolite

NASA Astrophysics Data System (ADS)

Farid, Nehal F.; Abdelwahab, Nada S.

2015-06-01

Flutamide is a hormone therapy used for men with advanced prostate cancer. Flutamide is highly susceptible to hydrolysis with the production of 3-(trifluoromethyl)aniline, which is reported to be one of its toxic metabolites, impurities and related substances according to BP and USP. Flutamide was found to be stable when exposed to oxidation by 30% hydrogen peroxide and direct sunlight for up to 4 h. Two accurate and sensitive spectrophotometric methods were used for determination of flutamide in bulk and in pharmaceutical formulations. Method (I) is the area under curve (AUC) spectrophotometric method that depends on measuring the AUC in the wavelength ranges of 275-305 nm and 350-380 nm and using Cramer's rule. The linearity range was found to be 1-35 μg/mL and 0.5-16 μg/mL for the drug and the degradate, respectively. In method (II), combination of the isoabsorptive and dual wavelength spectrophotometric methods was used for resolving the binary mixture. The absorbance at 249.2 nm (λiso) was used for determination of total mixture concentration, while the difference in absorbance between 232 nm and 341.2 nm was used for measuring the drug concentration. By subtraction, the degradate concentration was obtained. Beer's law was obeyed in the range of 2-35 μg/mL and 0.5-20 μg/mL for the drug and its degradate, respectively. The two methods were validated according to USP guidelines and were applied for determination of the drug in its pharmaceutical dosage form. Moreover AUC method was used for the kinetic study of the hydrolytic degradation of flutamide. The kinetic degradation of flutamide was found to follow pseudo-first order kinetics and is pH and temperature dependent. Activation energy, kinetic rate constants and t1/2 at different temperatures and pH values were calculated.

Concurrent estimation of amlodipine besylate, hydrochlorothiazide and valsartan by RP-HPLC, HPTLC and UV-spectrophotometry.

PubMed

Sharma, Manish; Kothari, Charmy; Sherikar, Omkar; Mehta, Priti

2014-01-01

Accurate, sensitive and reproducible reversed-phase high-performance liquid chromatography (RP-HPLC), high-performance thin-layer chromatography (HPTLC) and ultraviolet (UV) spectrophopometric methods were developed for the concurrent estimation of amlodipine besylate (AMLO), hydrochlorothiazide (HCTZ) and valsartan (VALS) in bulk and combined tablet dosage forms. For the RP-HPLC method, separation was achieved on a C18 column using potassium dihydrogen orthophosphate buffer (50 mM, pH 3.7) with 0.2% triethylamine as the modifier and acetonitrile in the ratio of 56:44 (v/v) as the mobile phase. Quantification was achieved using a photodiode array detector at 232 nm over a concentration range of 2-25 µg/mL for AMLO, 5-45 µg/mL for HCTZ and 20-150 µg/mL for VALS. For the HPTLC method, the drugs were separated by using ethyl acetate-methanol-toluene-ammonia (7.5:3:2:0.8, v/v/v/v) as the mobile phase. Quantification was achieved using UV detection at 242 nm over a concentration range of 100-600 ng/spot for AMLO, 150-900 ng/spot for HCTZ and 1,200-3,200 ng/spot for VALS. The UV-spectrophotometric simultaneous equation method was based on the measurement of absorbance at three wavelengths; i.e., at 237.6 nm (λmax of AMLO), 270.2 nm (λmax of HCTZ) and 249.2 nm (λmax of VALS) in methanol. Quantification was achieved over the concentration range of 2-20 µg/mL for AMLO, 5-25 µg/mL HCTZ and 10-50 µg/mL for VALS. All methods were validated according to International Conference on Harmonization guidelines and successfully applied to marketed pharmaceutical formulations. Additionally, the three methods were compared statistically by an analysis of variance test, which revealed no significant difference between the proposed methods with respect to accuracy and precision.

Two different spectrophotometric determinations of potential anticancer drug and its toxic metabolite.

PubMed

Farid, Nehal F; Abdelwahab, Nada S

2015-06-15

Flutamide is a hormone therapy used for men with advanced prostate cancer. Flutamide is highly susceptible to hydrolysis with the production of 3-(trifluoromethyl)aniline, which is reported to be one of its toxic metabolites, impurities and related substances according to BP and USP. Flutamide was found to be stable when exposed to oxidation by 30% hydrogen peroxide and direct sunlight for up to 4h. Two accurate and sensitive spectrophotometric methods were used for determination of flutamide in bulk and in pharmaceutical formulations. Method (I) is the area under curve (AUC) spectrophotometric method that depends on measuring the AUC in the wavelength ranges of 275-305 nm and 350-380nm and using Cramer's rule. The linearity range was found to be 1-35 μg/mL and 0.5-16 μg/mL for the drug and the degradate, respectively. In method (II), combination of the isoabsorptive and dual wavelength spectrophotometric methods was used for resolving the binary mixture. The absorbance at 249.2 nm (λiso) was used for determination of total mixture concentration, while the difference in absorbance between 232 nm and 341.2 nm was used for measuring the drug concentration. By subtraction, the degradate concentration was obtained. Beer's law was obeyed in the range of 2-35 μg/mL and 0.5-20 μg/mL for the drug and its degradate, respectively. The two methods were validated according to USP guidelines and were applied for determination of the drug in its pharmaceutical dosage form. Moreover AUC method was used for the kinetic study of the hydrolytic degradation of flutamide. The kinetic degradation of flutamide was found to follow pseudo-first order kinetics and is pH and temperature dependent. Activation energy, kinetic rate constants and t1/2 at different temperatures and pH values were calculated. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of laser wavelength and protein solder concentration on acute tissue repair using laser welding: initial results in a canine ureter model.

PubMed

Wright, E J; Poppas, D P

1997-01-01

Successful tissue approximation can be performed using low power laser energy combined with human albumin solder. In vitro studies were undertaken to investigate the acute repair strengths achieved using different laser wavelengths. Furthermore, we evaluated the change in repair strength with that resulted from changes in protein solder concentration. Intraluminal bursting pressure following ureterotomy repair was measured for the following laser wavelengths: 532, 808, 1,320, 2,100, and 10,600 nm. The tissue absorption characteristics of the 808-nm diode and the KTP-532-nm lasers required the addition of the exogenous chromophores indocyanine green and fluorescein, respectively. A 40% human albumin solder was incorporated in the repair of a 1.0-cm longitudinal defect in the canine ureter. Following determination of an optimal welding wavelength, human albumin solder of varying concentrations (25%, 38%, 45%, and 50%) were prepared and tested. The 1,320-nm YAG laser achieved the highest acute bursting pressure and was the most effective in this model. Of the concentrations of albumin tested, 50% human albumin yielded the greatest bursting pressures. We conclude that of the laser wavelengths evaluated, the 1,320-nm YAG achieves the strongest tissue weld in the acute ex vivo dog ureter model. In addition, when this laser system is used, the acute strength of a photothermal weld appears to be directly proportional to the concentration of human albumin solder in the range of 25 to 50%.

Radon decay products and 10-1100 nm aerosol particles in Postojna Cave

NASA Astrophysics Data System (ADS)

Bezek, M.; Gregorič, A.; Vaupotič, J.

2013-03-01

At the lowest point along the tourist route in Postojna Cave, the activity concentration of radon (222Rn) decay products and the number concentration and size distribution of aerosol particles in the size range of 10-1100 nm were monitored, with the focus on the unattached fraction (fun) of radon decay products (RnDPs), a key parameter in radon dosimetry. The total number concentration of aerosols during visits in summer was lower (700 cm-3) than in winter (2800 cm-3), and was dominated by <50 nm particles (related to unattached RnDPs) in summer and by >50 nm particles (related to the attached RnDPs) in winter. This explains the higher fun values in summer (0.75) and the lower winter measurement (0.04) and, consequently, DCFD values of 43.6 and 13.1 mSv WLM-1 respectively for the calculated dose conversion factors. The difference is caused by an enhanced inflow of fresh outside air, driven in winter by the higher air temperature in the cave compared to outside, resulting in the introduction of outside aerosol particles into the cave.

New Particle Formation in the Tropical UTLS Near Costa Rica: Contrast January and February with June and August

NASA Astrophysics Data System (ADS)

Wilson, J. C.; Saad, M. S.; Axisa, D.

2017-12-01

Aerosol size distributions were measured in the 4 nm to 1000 nm diameter range from the NASA WB-57 aircraft based in Costa Rica from 2004 through 2007. The measurements were made with the Nuclei Mode Aerosol Size Spectrometer (NMASS) and the Focused Cavity Aerosol Spectrometer (FCAS). The NMASS consists of 5 condensation particle counters (CPCs) each operated with a different supersaturation of the working fluid (FC-43). Therefore each CPC has a different lower size cut off. The size cutoffs are near 4nm 8nm, 16 nm, 32nm and 50nm in diameter. The FCAS is an optical particle counter that detects and sizes particles in the 100 to 1000 nm diameter range. By considering counting statistics, it is possible to identify those time intervals during which the counts in the 4 nm channel exceeded the counts in the 8 nm channel. Thus it is possible to clearly identify when there are particles in the 4 to 8 nm diameter range present in the size distribution. These particles have a short lifetime due to coagulation and their presence is taken to be evidence of recent new particle formation (NPF). The measurements made in January-February are contrasted with measurements made in June and August and differences are seen in the frequency with which NPF occurred. We examine the roles of air mass origin as determined by back trajectories, pre-existing aerosol surface area, atmospheric motions and trace gas concentrations in contributing to this difference.

Laser action benzimidazoles in various aggregate states

NASA Astrophysics Data System (ADS)

Gruzinskii, V. V.; Degtiarenko, K. M.; Shalaev, V. K.; Kopylova, T. N.; Verkhovskii, V. S.; Tarasenko, V. F.; Melchenko, S. V.

1983-04-01

Lasing has been obtained in solutions of benzimidazole (Bi) derivatives: 2-phenyl-Bi (with the band maximum lambda-r-max = 341-347 nm), 2-n-tolyl-Bi (344 nm), and 2-(4'-biphenilyl) Bi (366-374 nm). It is found that compounds of this class provide a basis for laser radiation covering a wide region of the spectrum. Lasing has been obtained on the vapors of 2-(4'-biphenilyl) Bi (361.2 nm) and 2-(n-tolyl) Bi (336.5 nm) with a pentane stabilizer of the excited states. High volatility, photostability, and lasing in wide ranges of concentration determine the efficiency of using this new class of compounds (chain arylbenzimidazoles) in lasers using the vapors of complex molecules.

Application of spectrophotometric, densitometric, and HPLC techniques as stability indicating methods for determination of Zaleplon in pharmaceutical preparations

NASA Astrophysics Data System (ADS)

Metwally, Fadia H.; Abdelkawy, M.; Abdelwahab, Nada S.

2007-12-01

Spectrophotometric, spectrodensitometric and HPLC are stability indicating methods described for determination of Zaleplon in pure and dosage forms. As Zaleplon is easily degradable, the proposed techniques in this manuscript are adopted for its determination in presence of its alkaline degradation product, namely N-[4-(3-cyano-pyrazolo[1,5a]pyridin-7-yl)-phenyl]- N-ethyl-acetamide. These approaches are successfully applied to quantify Zaleplon using the information included in the absorption spectra of appropriate solutions. The second derivative (D 2) spectrophotometric method, allows determination of Zaleplon without interference of its degradate at 235.2 nm using 0.01N HCl as a solvent with obedience to Beer's law over a concentration range of 1-10 μg ml -1 with mean percentage recovery 100.24 ± 0.86%. The first derivative of the ratio spectra ( 1DD) based on the simultaneous use of ( 1DD) and measurement at 241.8 nm using the same solvent and over the same concentration range as (D 2) spectrophotometric method, with mean percentage recovery 99.9 ± 1.07%. The spectrodensitometric analysis allows the separation and quantitation of Zaleplon from its degradate on silica gel plates using chloroform:acetone:ammonia solution (9:1:0.2 by volume) as a mobile phase. This method depends on quantitave densitometric evaluation of thin layer chromatogram of Zaleplon at 338 nm over a concentration range of 0.2-1 μg band -1, with mean percentage recovery 99.73 ± 1.35. Also a reversed-phase liquid chromatographic method using 5-C8 (22 cm × 4.6 mm i.d. 5 μm particle size) column was described and validated for quantitation of Zaleplon using acetonitrile:deionised water (35:65, v/v) as a mobile phase using Paracetamol as internal standard and a flow rate of 1.5 ml min -1 with UV detection of the effluent at 232 nm at ambient temperature over a concentration range of 2-20 μg ml -1 with mean percentage recovery 100.19 ± 1.15%. The insignificance difference of the proposed methods results with those of the reference one proved their accuracy and precision.

Neem oil (Azadirachta indica) nanoemulsion--a potent larvicidal agent against Culex quinquefasciatus.

PubMed

Anjali, C H; Sharma, Yamini; Mukherjee, Amitava; Chandrasekaran, Natarajan

2012-02-01

Nanoemulsion composed of neem oil and non-ionic surfactant Tween 20, with a mean droplet size ranging from 31.03 to 251.43 nm, was formulated for various concentrations of the oil and surfactant. The larvicidal effect of the formulated neem oil nanoemulsion was checked against Culex quinquefasciatus. O/W emulsion was prepared using neem oil, Tween 20 and water. Nanoemulsion of 31.03 nm size was obtained at a 1:3 ratio of oil and surfactant, and it was found to be stable. The larger droplet size (251.43 nm) shifted to a smaller size of 31.03 nm with increase in the concentration of Tween 20. The viscosity of the nanoemulsion increased with increasing concentration of Tween 20. The lethal concentration (LC50) of the nanoemulsion against Cx. quinquefasciatus was checked for 1:0.30, 1:1.5 and 1:3 ratios of oil and surfactant respectively. The LC50 decreased with droplet size. The LC50 for the ratio 1:3 nanoemulsions was 11.75 mg L(-1). The formulated nanoemulsion of 31.03 nm size was found to be an effective larvicidal agent. This is the first time that a neem oil nanoemulsion of this droplet size has been reported. It may be a good choice as a potent and selective larvicide for Cx. quinquefasciatus. Copyright © 2011 Society of Chemical Industry.

LASP-02: In Vitro Cell Cytotoxicity Evaluation in Kras/p53 Pancreatic Ductal Adenocarcinoma (PDAC) Derived Mouse Cells | Frederick National Laboratory for Cancer Research

Cancer.gov

The Laboratory Animal Sciences Program will assess the in vitro potency of candidate compounds via a conventional cell-based toxicity assay (XTT living cell test) in a series of six drug concentrations (ranging from 0.1 nM to 50,000 nM) of a single a

Spectrophotometric Methods for Simultaneous Determination of Sofosbuvir and Ledipasvir (HARVONI Tablet): Comparative Study with Two Generic Products.

PubMed

Abo-Talib, Nisreen F; El-Ghobashy, Mohamed R; Tammam, Marwa H

2017-07-01

Sofosbuvir and ledipasvir are the first drugs in a combination pill to treat chronic hepatitis C virus. Simple, sensitive, and rapid spectrophotometric methods are presented for the determination of sofosbuvir and ledipasvir in their combined dosage form. These methods were based on direct measurement of ledipasvir at 333 nm (due to the lack of interference of sofosbuvir) over a concentration range of 4.0-14.0 µg/mL, with a mean recovery of 100.78 ± 0.64%. Sofosbuvir was determined, without prior separation, by third-derivative values at 281 nm; derivative ratio values at 265.8 nm utilizing 5.0 µg/mL ledipasvir as a divisor; the ratio difference method using values at 270 and 250 nm using 5.0 µg/mL ledipasvir as a divisor; and the ratio subtraction method using values at 261 nm. These methods were found to be linear for sofosbuvir over a concentration range of 5.0-35.0 µg/mL. The suggested methods were validated according to International Conference on Harmonization guidelines. Statistical analysis of the results showed no significant difference between the proposed methods and the manufacturer's LC method of determination with respect to accuracy and precision. These methods were used to compare the equivalence of an innovator drug dosage form and two generic drug dosage forms of the same strength.

Evidence for the formation of SiGe nanoparticles in Ge-implanted Si 3N 4

DOE PAGES

Mirzaei, S.; Kremer, F.; Feng, R.; ...

2017-03-14

SiGe nanoparticles were formed in an amorphous Si 3N 4 matrix by Ge + ion implantation and thermal annealing. The size of the nanoparticles was determined by transmission electron microscopy and their atomic structure by x-ray absorption spectroscopy. Nanoparticles were observed for excess Ge concentrations in the range from 9 to 12 at. % after annealing at temperatures in the range from 700 to 900 °C. The average nanoparticle size increased with excess Ge concentration and annealing temperature and varied from an average diameter of 1.8±0.2 nm for the lowest concentration and annealing temperature to 3.2±0.5 nm for the highestmore » concentration and annealing temperature. Our study demonstrates that the structural properties of embedded SiGe nanoparticles in amorphous Si 3N 4 are sensitive to the implantation and post implantation conditions. Furthermore, we demonstrate that ion implantation is a novel pathway to fabricate and control the SiGe nanoparticle structure and potentially useful for future optoelectronic device applications.« less

AlGaN materials for semiconductor sensors and emitters in 200- to 365-nm range

NASA Astrophysics Data System (ADS)

Usikov, Alexander S.; Shapvalova, Elizaveta V.; Melnik, Yuri V.; Ivantsov, Vladimir A.; Dmitriev, Vladimir A.; Collins, Charles J.; Sampath, Anand V.; Garrett, Gregory A.; Shen, Paul H.; Wraback, Michael

2004-12-01

In this paper we report on the fabrication and characterization of GaN, AlGaN, and AlN layers grown by hydride vapor phase epitaxy (HVPE). The layers were grown on 2-inch and 4-inch sapphire and 2-inch silicon carbide substrates. Thickness of the GaN layers was varied from 2 to 80 microns. Surface roughness, Rms, for the smoothest GaN layers was less than 0.5 nm, as measured by AFM using 10 μm x 10 μm scans. Background Nd-Na concentration for undoped GaN layers was less than 1x1016 cm-3. For n-type GaN layers doped with Si, concentration Nd-Na was controlled from 1016 to 1019 cm-3. P-type GaN layers were fabricated using Mg doping with concentration Na-Nd ranging from 4x1016 to 3x1018 cm-3, for various samples. Zn doping also resulted in p-type GaN formation with concnetration ND-NA in the 1017 cm-3 range. UV transmission, photoluminescence, and crystal structure of AlGaN layers with AlN concentration up to 85 mole.% were studied. Dependence of optical band gap on AlGaN alloy composition was measured for the whole composition range. Thick (up to 75 microns) crack-free AlN layers were grown on SiC substrates. Etch pit density for such thick AlN layers was in the 107 cm-2 range.

Deposition velocity of ultrafine particles measured with the Eddy-Correlation Method over the Nansen Ice Sheet (Antarctica)

NASA Astrophysics Data System (ADS)

Contini, D.; Donateo, A.; Belosi, F.; Grasso, F. M.; Santachiara, G.; Prodi, F.

2010-08-01

This work reports an analysis of the concentration, size distribution, and deposition velocity of atmospheric particles over snow and iced surfaces on the Nansen Ice Sheet (Antarctica). Measurements were performed using the eddy-correlation method at a remote site during the XXII Italian expedition of the National Research Program in Antarctica (PNRA) in 2006. The measurement system was based on a condensation particle counter (CPC) able to measure particles down to 9 nm in diameter with a 50% efficiency and a Differential Mobility Particle Sizer for evaluating particle size distributions from 11 to 521 nm diameter in 39 channels. A method based on postprocessing with digital filters was developed to take into account the effect of the slow time response of the CPC. The average number concentration was 1338 cm-3 (median, 978 cm-3; interquartile range, 435-1854 cm-3). Higher concentrations were observed at low wind velocities. Results gave an average deposition velocity of 0.47 mm/s (median, 0.19 mm/s; interquartile range, -0.21 -0.88 mm/s). Deposition increased with the friction velocity and was on average 0.86 mm/s during katabatic wind characterized by velocities higher than 4 m/s. Observed size distributions generally presented two distinct modes, the first at approximately 15-20 nm and the second (representing on average 70% of the total particles) at 60-70 nm. Under strong-wind conditions, the second mode dominated the average size distribution.

Simultaneous retrieval of daytime O(3P) and O3 concentrations in the altitude interval 80 - 100 km.

NASA Astrophysics Data System (ADS)

Yankovsky, Valentine; Manuilova, Rada; Koval, Andrey

2017-04-01

We propose methods of simultaneously independent retrievals of the key components of Mesosphere and Lower Thermosphere (MLT) [O3] and [O(3P)]. The altitude profile of ozone concentration, [O3], can be measured by direct method of the measurement of absorbing radiation from the Sun or the stars in the UV range of the spectrum. However, this method is most often realized in twilight. Retrieval of daytime [O3] depends on a prior information about the O(3P) altitude profile. Vice versa, atomic oxygen concentration, [O(3P)], is usually retrieved from the measured values of [O3]. The problem of independent and simultaneous retrieval of [O3] and [O(3P)] can be solved by using individual proxy for each of the target component. Using a sensitivity study and uncertainty analysis of the contemporary model of O3 and O2 photolysis in the MLT, YM2011, we determined that populations of three excited electronic-vibrational levels O2(b1, v = 0, 1, 2) and of metastable O(1D) atom depend on [O(3P)] and [O3] concentrations. For [O(3P)] retrieval the following transitions should be used: O2(b1, v') -> O2(X3, v") which produce emissions: (a) at 780.4 nm in the band (v' = 2, v" = 2) and at 697.0 nm in the band (2, 1) with the uncertainty of retrieval smaller than 30% for the whole altitude range 80 - 100 km; (b) at 771.0 nm in the band (1, 1), 688.4 nm in the band (1, 0) and at 874.4 nm in the band (1, 2) with the uncertainty of retrieval about 30% above 90 km. For [O3] retrieval the following transitions should be used: O2(b1, v') -> O2(X3, v") which produce emissions: (c) at 762.1 nm in the band (0, 0) and at 864.7 nm in the band (0, 1) with the uncertainty of retrieval 20 - 25% for the altitude range 80 - 85 km and smaller than 20% in the interval 85 - 95 km; (d) in the line of O(1D) 630.0 nm with the uncertainty of retrieval 10 - 15% in the interval 80 - 95 km. Above 95 km the uncertainty of [O3] retrieval grows and reaches up to 80% at 100 km for all suggested proxies. For simultaneously [O3] and [O(3P)] retrievals the observations of above mentioned emissions (a) or (b) and (c) or (d) could be used.

Characterization of exposures to airborne nanoscale particles during friction stir welding of aluminum.

PubMed

Pfefferkorn, Frank E; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; McCarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M Abbas; Gruetzmacher, George; Hoover, Mark D

2010-07-01

Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 microm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 microm) with 1-s resolution, lung deposited surface areas, and PM(2.5) concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 microm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at approximately 30 and approximately 550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at approximately 4.0 x 10(5) particles cm(-3), whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm(-3), depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10-100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) microg m(-3); the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial operations.

Characterization of Exposures to Airborne Nanoscale Particles During Friction Stir Welding of Aluminum

PubMed Central

Pfefferkorn, Frank E.; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; Mccarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M. Abbas; Gruetzmacher, George; Hoover, Mark D.

2010-01-01

Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 μm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 μm) with 1-s resolution, lung deposited surface areas, and PM2.5 concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 μm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at ∼30 and ∼550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at ∼4.0 × 105 particles cm−3, whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm−3, depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10–100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) μg m−3; the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial operations. PMID:20453001

Derivative spectrophotometric method for simultaneous determination of clindamycin phosphate and tretinoin in pharmaceutical dosage forms

PubMed Central

2013-01-01

A derivative spectrophotometric method was proposed for the simultaneous determination of clindamycin and tretinoin in pharmaceutical dosage forms. The measurement was achieved using the first and second derivative signals of clindamycin at (1D) 251 nm and (2D) 239 nm and tretinoin at (1D) 364 nm and (2D) 387 nm. The proposed method showed excellent linearity at both first and second derivative order in the range of 60–1200 and 1.25–25 μg/ml for clindamycin phosphate and tretinoin respectively. The within-day and between-day precision and accuracy was in acceptable range (CV<3.81%, error<3.20%). Good agreement between the found and added concentrations indicates successful application of the proposed method for simultaneous determination of clindamycin and tretinoin in synthetic mixtures and pharmaceutical dosage form. PMID:23575006

Laser induced fluorescence in algae: A new technique for remote detection

NASA Technical Reports Server (NTRS)

Friedman, E. J.; Hickman, G. D.

1972-01-01

Measurements of the absorption and fluorescence spectra were obtained for four various types of marine and fresh water algae using a pulsed N2/Ne dye laser as the source of excitation. The absorption maxima for the algae ranged from 420 to 675 nm, while their fluorescent spectra ranged from 580 to 685 nm. It appears feasible that various algal species can be identified by detection of their fluorescent signatures using a tunable laser as the excitation source. However, if one is concerned only with detection of chlorophyll a, the optimum excitation is approximately 600 + 50 nm while detection is at 685 nm. An analysis of both calculations and laboratory results indicates that it should be feasible to measure chlorophyll a in concentrations as low as 1.0 mg/m3 using a 100 kW peak pulsed laser from an altitude of 500 meters.

Characterization of ions at Alpine waterfalls

NASA Astrophysics Data System (ADS)

Kolarž, P.; Gaisberger, M.; Madl, P.; Hofmann, W.; Ritter, M.; Hartl, A.

2012-04-01

During a three-year field campaign of measuring waterfall generated ions, we monitored five different waterfalls in the Austrian Alps. Most measurements were performed at the Krimml waterfall (Salzburg, Austria), which is the biggest waterfall in Europe, and the Gartl waterfall (Mölltal, Austria). We characterized spatial, time and size distributions of waterfall-generated ions under the influence of surrounding topography. The smallest ions with boundary diameters of 0.9, 1.5 and 2 nm, were measured with a cylindrical air ion detector (CDI-06), while ion sizes from 5.5 to 350 nm were measured using a modified Grimm SMPS aerosol spectrometer. High negative ion concentration gradients are detected in the vicinity of the waterfalls, whereas the increase of positive ions was only moderate. Ions in the nano range were the most abundant at 2 nm, and at 120 nm in the sub-micrometer range.

Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

NASA Astrophysics Data System (ADS)

Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

2017-12-01

Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

Influence of the chlorine concentration on the radiation efficiency of a XeCl exciplex lamp

NASA Astrophysics Data System (ADS)

Avtaeva, S. V.; Sosnin, E. A.; Saghi, B.; Panarin, V. A.; Rahmani, B.

2013-09-01

The influence of the chlorine concentration on the radiation efficiency of coaxial exciplex lamps (excilamps) excited by a dielectric barrier discharge (DBD) in binary Xe-Cl2 mixtures at pressures of 240-250 Torr is investigated experimentally and theoretically. The experiments were carried out at Cl2 concentrations in the range of 0.01-1%. The DBD characteristics were calculated in the framework of a one-dimensional hydrodynamic model at Cl2 concentrations in the range of 0.1-5%. It is found that the radiation intensities of the emission bands of Xe*2(172 nm) and XeCl* (308 nm) are comparable when the chlorine concentration in the mixture is in the range of 0.01-0.1%. In this case, in the mixture, the radiation intensity of the Xe*2 molecule rapidly decreases with increasing Cl2 concentration and, at a chlorine concentration of ≥0.2%, the radiation of the B → X band of XeCl* molecules with a peak at 308 nm dominates in the discharge radiation. The radiation efficiency of this band reaches its maximum value at chlorine concentrations in the range of 0.4-0.5%. The calculated efficiencies of DBD radiation exceed those obtained experimentally. This is due to limitations of the one-dimensional model, which assumes the discharge to be uniform in the transverse direction, whereas the actual excilamp discharge is highly inhomogeneous. The influence of the chlorine concentration on the properties of the DBD plasma in binary Xe-Cl2 mixtures is studied numerically. It is shown that an increase in the Cl2 concentration in the mixture leads to the attachment of electrons to chlorine atoms and a decrease in the electron density and discharge conductivity. As a result, the electric field and the voltage drop across the discharge gap increase, which, in turn, leads to an increase in the average electron energy and the probability of dissociation of Cl2 molecules and ionization of Xe atoms and Cl2 molecules. The total energy deposited in the discharge rises with increasing chlorine concentration due to an increase in the power spent on the heating of positive and negative ions. The power dissipated by electrons decreases with increasing chlorine concentration in the working mixture. Recommendations on the choice of the chlorine content in the mixture for reducing the intensity of VUV radiation of the second continuum of the Xe*2 excimer without a substantial decrease in the excilamp efficiency are formulated.

Resist image quality control via acid diffusion constant and/or photodecomposable quencher concentration in the fabrication of 11 nm half-pitch line-and-space patterns using extreme-ultraviolet lithography

NASA Astrophysics Data System (ADS)

Kozawa, Takahiro; Santillan, Julius Joseph; Itani, Toshiro

2018-05-01

Extreme-ultraviolet (EUV) lithography will be applied to the high-volume production of semiconductor devices with 16 nm half-pitch resolution and is expected to be extended to that of devices with 11 nm half-pitch resolution. With the reduction in the feature sizes, the control of acid diffusion becomes a significant concern. In this study, the dependence of resist image quality on T PEB D acid and photodecomposable quencher concentration was investigated by the Monte Carlo method on the basis of the sensitization and reaction mechanisms of chemically amplified EUV resists. Here, T PEB and D acid are the postexposure baking (PEB) time and the acid diffusion constant, respectively. The resist image quality of 11 nm line-and-space patterns is discussed in terms of line edge roughness (LER) and stochastic defect generation. For the minimization of LER, it is necessary to design and control not only the photodecomposable quencher concentration but also T PEB D acid. In this case, D acid should be adjusted to be 0.3–1.5 nm2 s‑1 for a PEB time of 60 s with optimization of the balance among LER and stochastic pinching and bridging. Even if it is difficult to decrease D acid to the range of 0.3–1.5 nm2 s‑1, the image quality can still be controlled via only the photodecomposable quencher concentration, although LER and stochastic pinching and bridging are slightly increased. In this case, accurate control of the photodecomposable quencher concentration and the reduction in the initial standard deviation of the number of protected units are required.

A high gradient and strength bioseparator with nano-sized immunomagnetic particles for specific separation and efficient concentration of E. coli O157:H7

NASA Astrophysics Data System (ADS)

Lin, Jianhan; Li, Min; Li, Yanbin; Chen, Qi

2015-03-01

Sample pretreatment is a key to rapid screening of pathogens for prevention and control of foodborne diseases. Magnetic immunoseparation is a specific method based on antibody-antigen reaction to capture the target bacteria and concentrate them in a smaller-volume buffer. The use of nano-sized magnetic particles could improve the separation efficiency of bacteria but require much higher gradient and strength magnetic field. In this study, a strong magnetic bioseparator with a mean field strength of 1.35 T and a mean gradient of 90 T/m was developed with the use of the 30 nm and 180 nm magnetic particles to specifically separate and efficiently concentrate foodborne bacterial pathogens using Escherichia coli O157:H7 as a model bacterium. The polyclonal antibodies against E. coli were evaluated using Dot ELISA analysis for their good affinity with the target bacteria and then used to modify the surface of the magnetic nanoparticles by 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC·HCl) method and streptavidin-biotin binding. The magnetic particle concentrations were optimized to be 40 μg/ml and 100 μg/ml for the 30 nm and 180 nm particles, respectively, the immunoreaction time was optimized to be 45 min for both sizes of particles, and the separation times were optimized to be 60 min and 2 min for the 30 nm and 180 nm particles, respectively. The total magnetic separation time was 2 h and 1 h for the 30 nm and 180 nm particles, respectively. The experimental results demonstrated that the bioseparator with the use of either 30 nm or 180 nm immunomagnetic particles could achieve a separation efficiency of >90% for E. coli O157:H7 at the concentrations ranging from 102 to 105 cfu/ml. No obvious interferences from non-target foodborne pathogens, such as SalmonellaTyphimurium and Listeria innocua, were found. For overall consideration of the consuming time, the cost, and the separation efficiency, the 180 nm magnetic particles are practical for rapid screening applications; however the 30 nm magnetic particles are preferable for specific detection applications. This immunomagnetic bioseparator can be integrated with either conventional culture methods or some rapid detection methods, such as biosensors and PCR, for more sensitive detection of foodborne pathogens.

Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 1: Aerosol size distribution, hygroscopicity, and new model parametrizations for CCN prediction

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

Pöhlker, Mira L.; Pöhlker, Christopher; Ditas, Florian

Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a 1-year period and full seasonal cycle (March 2014–February 2015). Our measurements provide a climatology of CCN properties characteristic of a remote central Amazonian rain forest site.The CCN measurements were continuously cycled through 10 levels of supersaturation ( S=0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The mean critical diameters of CCN activation range from 43 nm at S = 1.10 % to 172more » nm at S = 0.11 %. Furthermore, the particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode ( κ Ait = 0.14 ± 0.03), higher values for the accumulation mode ( κ Acc = 0.22 ± 0.05), and an overall mean value of κ mean = 0.17 ± 0.06, consistent with high fractions of organic aerosol.The hygroscopicity parameter, κ, exhibits remarkably little temporal variability: no pronounced diurnal cycles, only weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. Here, we find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes.For modeling purposes, we compare different approaches of predicting CCN number concentration and present a novel parametrization, which allows accurate CCN predictions based on a small set of input data.« less

Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 1: Aerosol size distribution, hygroscopicity, and new model parametrizations for CCN prediction

DOE PAGES

Pöhlker, Mira L.; Pöhlker, Christopher; Ditas, Florian; ...

2016-12-20

Size-resolved long-term measurements of atmospheric aerosol and cloud condensation nuclei (CCN) concentrations and hygroscopicity were conducted at the remote Amazon Tall Tower Observatory (ATTO) in the central Amazon Basin over a 1-year period and full seasonal cycle (March 2014–February 2015). Our measurements provide a climatology of CCN properties characteristic of a remote central Amazonian rain forest site.The CCN measurements were continuously cycled through 10 levels of supersaturation ( S=0.11 to 1.10 %) and span the aerosol particle size range from 20 to 245 nm. The mean critical diameters of CCN activation range from 43 nm at S = 1.10 % to 172more » nm at S = 0.11 %. Furthermore, the particle hygroscopicity exhibits a pronounced size dependence with lower values for the Aitken mode ( κ Ait = 0.14 ± 0.03), higher values for the accumulation mode ( κ Acc = 0.22 ± 0.05), and an overall mean value of κ mean = 0.17 ± 0.06, consistent with high fractions of organic aerosol.The hygroscopicity parameter, κ, exhibits remarkably little temporal variability: no pronounced diurnal cycles, only weak seasonal trends, and few short-term variations during long-range transport events. In contrast, the CCN number concentrations exhibit a pronounced seasonal cycle, tracking the pollution-related seasonality in total aerosol concentration. Here, we find that the variability in the CCN concentrations in the central Amazon is mostly driven by aerosol particle number concentration and size distribution, while variations in aerosol hygroscopicity and chemical composition matter only during a few episodes.For modeling purposes, we compare different approaches of predicting CCN number concentration and present a novel parametrization, which allows accurate CCN predictions based on a small set of input data.« less

Application of the [3H]Leucine Incorporation Technique for Quantification of Bacterial Secondary Production Associated with Decaying Wetland Plant Litter

PubMed Central

Gillies, Jane E.; Kuehn, Kevin A.; Francoeur, Steven N.; Neely, Robert K.

2006-01-01

The radiolabeled leucine incorporation technique for quantifying rates of bacterial production has increased in popularity since its original description for bacterioplankton communities. Prior studies addressing incorporation conditions (e.g., substrate saturation) for bacterial communities in other habitats, such as decaying plant litter, have reported a wide range of final leucine concentrations (400 nM to 50 μM) required to achieve saturation-level uptake. We assessed the application of the [3H]leucine incorporation procedure for measuring bacterial production on decaying wetland plant litter. Substrate saturation experiments (nine concentrations, 10 nM to 50 μM final leucine concentration) were conducted on three dates for microbial communities colonizing the submerged litter of three emergent plant species (Typha angustifolia, Schoenoplectus validus, and Phragmites australis). A modified [3H]leucine protocol was developed by coupling previously described incubation and alkaline extraction protocols with microdialysis (500 molecular weight cutoff membrane) of the final radiolabeled protein extract. The incorporation of [3H]leucine into protein exhibited a biphasic saturation curve, with lower apparent Km values ranging from 400 nM to 4.2 μM depending on the plant species studied. Upper apparent Km values ranged from 1.3 to 59 μM. These results suggest differential uptake by litter-associated microbial assemblages, with the lower apparent Km values possibly representing bacterial uptake and higher apparent Km values representing a combination of both bacterial and nonbacterial (e.g., eukaryotic) uptake. PMID:16957215

Stabilization of diketo tautomer of curcumin by premicellar anionic surfactants: UV-Visible, fluorescence, tensiometric and TD-DFT evidences

NASA Astrophysics Data System (ADS)

Dutta, Anisha; Boruah, Bornali; Manna, Arun K.; Gohain, Biren; Saikia, Palash M.; Dutta, Robin K.

2013-03-01

A newly observed UV band of aqueous curcumin, a biologically important molecule, in presence of anionic surfactants, viz., sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate (SDBS), and sodium dodecylsulfonate (SDSN) in buffered aqueous solutions has been studied experimentally and theoretically. The 425 nm absorption band of curcumin disappears and a new UV-band is observed at 355 nm on addition of the surfactants in the submicellar concentration range which is reversed as the surfactant concentration approaches the critical micelle concentration (CMC). The observed spectral absorption, fluorescence intensity and surface tension behavior, under optimal experimental conditions of submicellar concentration ranges of the surfactants in the pH range of 2.00-7.00, indicate that the new band is due to the β-diketo tautomer of curcumin stabilized by interactions between curcumin and the anionic surfactants. The stabilization of the diketo tautomer by submicellar anionic surfactants described here as well as by submicellar cationic surfactant, reported recently, is unique as this is the only such behavior observed in presence of submicellar surfactants of both charge types. The experimental results are in good agreement with the theoretical calculations using ab initio density functional theory combined with time dependent density functional theory (TD-DFT) calculations.

Supersensitive and selective detection of picric acid explosive by fluorescent Ag nanoclusters.

PubMed

Zhang, Jian Rong; Yue, Yuan Yuan; Luo, Hong Qun; Li, Nian Bing

2016-02-07

Picric acid (PA) explosive is a hazard to public safety and health, so the sensitive and selective detection of PA is very important. In the present work, polyethyleneimine stabilized Ag nanoclusters were successfully used for the sensitive and selective quantification of PA on the basis of fluorescence quenching. The quenching efficiency of Ag nanoclusters is proportional to the concentration of PA and the logarithm of PA concentration over two different concentration ranges (1.0 nM-1 μM for the former and 0.25-20 μM for the latter), thus the proposed quantitative strategy for PA provides a wide linear range of 1.0 nM-20 μM. The detection limit based on 3σ/K is 0.1 nM. The quenching mechanism of Ag nanoclusters by PA is discussed in detail. The results indicate that the selective detection of PA over other nitroaromatics including 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), p-nitrotoluene (p-NT), m-dinitrobenzene (m-DNB), and nitrobenzene (NB), is due to the electron transfer and energy transfer between PA and polyethyleneimine-capped Ag nanoclusters. In addition, the experimental data obtained for the analysis of artificial samples show that the proposed PA sensor is potentially applicable in the determination of trace PA explosive in real samples.

Molybdenum Availability Is Key to Nitrate Removal in Contaminated Groundwater Environments

PubMed Central

Thorgersen, Michael P.; Lancaster, W. Andrew; Vaccaro, Brian J.; Poole, Farris L.; Rocha, Andrea M.; Mehlhorn, Tonia; Pettenato, Angelica; Ray, Jayashree; Waters, R. Jordan; Melnyk, Ryan A.; Chakraborty, Romy; Deutschbauer, Adam M.; Arkin, Adam P.

2015-01-01

The concentrations of molybdenum (Mo) and 25 other metals were measured in groundwater samples from 80 wells on the Oak Ridge Reservation (ORR) (Oak Ridge, TN), many of which are contaminated with nitrate, as well as uranium and various other metals. The concentrations of nitrate and uranium were in the ranges of 0.1 μM to 230 mM and <0.2 nM to 580 μM, respectively. Almost all metals examined had significantly greater median concentrations in a subset of wells that were highly contaminated with uranium (≥126 nM). They included cadmium, manganese, and cobalt, which were 1,300- to 2,700-fold higher. A notable exception, however, was Mo, which had a lower median concentration in the uranium-contaminated wells. This is significant, because Mo is essential in the dissimilatory nitrate reduction branch of the global nitrogen cycle. It is required at the catalytic site of nitrate reductase, the enzyme that reduces nitrate to nitrite. Moreover, more than 85% of the groundwater samples contained less than 10 nM Mo, whereas concentrations of 10 to 100 nM Mo were required for efficient growth by nitrate reduction for two Pseudomonas strains isolated from ORR wells and by a model denitrifier, Pseudomonas stutzeri RCH2. Higher concentrations of Mo tended to inhibit the growth of these strains due to the accumulation of toxic concentrations of nitrite, and this effect was exacerbated at high nitrate concentrations. The relevance of these results to a Mo-based nitrate removal strategy and the potential community-driving role that Mo plays in contaminated environments are discussed. PMID:25979890

Size-segregated particle number concentrations and respiratory emergency room visits in Beijing, China.

PubMed

Leitte, Arne Marian; Schlink, Uwe; Herbarth, Olf; Wiedensohler, Alfred; Pan, Xiao-Chuan; Hu, Min; Richter, Matthia; Wehner, Birgit; Tuch, Thomas; Wu, Zhijun; Yang, Minjuan; Liu, Liqun; Breitner, Susanne; Cyrys, Josef; Peters, Annette; Wichmann, H-Erich; Franck, Ulrich

2011-04-01

The link between concentrations of particulate matter (PM) and respiratory morbidity has been investigated in numerous studies. The aim of this study was to analyze the role of different particle size fractions with respect to respiratory health in Beijing, China. Data on particle size distributions from 3 nm to 1 µm; PM10 (PM ≤ 10 µm), nitrogen dioxide (NO(2)), and sulfur dioxide concentrations; and meteorologic variables were collected daily from March 2004 to December 2006. Concurrently, daily counts of emergency room visits (ERV) for respiratory diseases were obtained from the Peking University Third Hospital. We estimated pollutant effects in single- and two-pollutant generalized additive models, controlling for meteorologic and other time-varying covariates. Time-delayed associations were estimated using polynomial distributed lag, cumulative effects, and single lag models. Associations of respiratory ERV with NO(2) concentrations and 100-1,000 nm particle number or surface area concentrations were of similar magnitude-that is, approximately 5% increase in respiratory ERV with an interquartile range increase in air pollution concentration. In general, particles < 50 nm were not positively associated with ERV, whereas particles 50-100 nm were adversely associated with respiratory ERV, both being fractions of ultrafine particles. Effect estimates from two-pollutant models were most consistent for NO(2). Present levels of air pollution in Beijing were adversely associated with respiratory ERV. NO(2) concentrations seemed to be a better surrogate for evaluating overall respiratory health effects of ambient air pollution than PM(10) or particle number concentrations in Beijing.

Hydrogen concentrations as an indicator of the predominant terminal electron-accepting reactions in aquatic sediments

USGS Publications Warehouse

Lovley, D.R.; Goodwin, S.

1988-01-01

Factors controlling the concentration of dissolved hydrogen gas in anaerobic sedimentary environments were investigated. Results, presented here or previously, demonstrated that, in sediments, only microorganisms catalyze the oxidation of H2 coupled to the reduction of nitrate, Mn(IV), Fe(III), sulfate, or carbon dioxide. Theoretical considerations suggested that, at steady-state conditions, H2 concentrations are primarily dependent upon the physiological characteristics of the microorganism(s) consuming the H2 and that organisms catalyzing H2 oxidation, with the reduction of a more electrochemically positive electron acceptor, can maintain lower H2 concentrations than organisms using electron acceptors which yield less energy from H2 oxidation. The H2 concentrations associated with the specified predominant terminal electron-accepting reactions in bottom sediments of a variety of surface water environments were: methanogenesis, 7-10 nM; sulfate reduction, 1-1.5 nM; Fe(III) reduction, 0.2 nM; Mn(IV) or nitrate reduction, less than 0.05 nM. Sediments with the same terminal electron acceptor for organic matter oxidation had comparable H2 concentrations, despite variations in the rate of organic matter decomposition, pH, and salinity. Thus, each terminal electron-accepting reaction had a unique range of steady-state H2 concentrations associated with it. Preliminary studies in a coastal plain aquifer indicated that H2 concentrations also vary in response to changes in the predominant terminal electron-accepting process in deep subsurface environments. These studies suggest that H2 measurements may aid in determining which terminal electron-accepting reactions are taking place in surface and subsurface sedimentary environments. ?? 1988.

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon

PubMed Central

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M.; Cooke, Helen J.; Wood, Jackie D.

2009-01-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1–3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1–3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1–3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P < 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles. PMID:19179625

Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon.

PubMed

Fei, Guijun; Wang, Yu-Zhong; Liu, Sumei; Hu, Hong-Zhen; Wang, Guo-Du; Qu, Mei-Hua; Wang, Xi-Yu; Xia, Yun; Sun, Xiaohong; Bohn, Laura M; Cooke, Helen J; Wood, Jackie D

2009-04-01

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current (Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1-3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1-3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1-3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed (P<0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles.

Determining CDOM Absorption Spectra in Diverse Aquatic Environments Using a Multiple Pathlength, Liquid Core Waveguide System

NASA Technical Reports Server (NTRS)

Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

2001-01-01

We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, aCDOM, and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values and showed a linear response across all four pathlengths. Values of aCDOM measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of aCDOM for MPLCW measurements was 0.002 - 231.5 m-1. At low CDOM concentrations spectrophotometric aCDOM were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples.

Direct visual observations of nanoparticles in the Celtic Sea

NASA Astrophysics Data System (ADS)

Rusiecka, D.; Gledhill, M.; Achterberg, E. P.; Elgy, C.; Connelly, D.

2016-02-01

Shelf seas are a substantial source of dissolved iron and other biologically essential dissolved trace metals (dTM) to the open ocean. The concentration of dTM in seawater is strongly influenced by their physico-chemical forms. The role of submicron colloids on the stabilization and transport of dTM in the soil porewaters has already been recognized. However, the influence of nanoparticles (NP) on dTM stabilization in marine systems and consequently on their long range off-shelf transport is still very poorly constrained. The characterization of marine NP is fundamental to understand their chemical behaviour. Here, we report the first direct visual investigation into the formation, water column size distribution and seasonal variation of NP in the Celtic Sea with supportive examination of particle morphology. Samples were collected from surface (depth range), intermediate (depth range) and deep (depth range) waters in December 2014, April 2015 and July 2015. Nanoparticles (>3 KDa) were concentrated by stirred cell ultrafiltration and imaged using Atomic Force Microscopy and Transmission Electron Microscopy. NP size distributions from the spring cruise showed that they mainly existed in the smallest 0.4-1 nm fraction in surface- and bottom-waters, whereas the summer season was dominated by 0.4-1 nm fraction at all depths. In winter NP in bottom-waters were found predominantly in bigger 1-2 nm fraction.

Structure of aqueous cesium metaborate solutions by X-ray scattering and DFT calculation

NASA Astrophysics Data System (ADS)

Zhang, W. Q.; Fang, C. H.; Fang, Y.; Zhu, F. Y.; Zhou, Y. Q.; Liu, H. Y.; Li, W.

2018-05-01

In the present work, precise radial distribution function (RDF) of cesium metaborate solutions with salt-water molar ratio of 1:25, 1:30 and 1:35 in large scattering vector range (3.91-214.26 nm-1) were obtained by X-ray scattering. Polyborate species were given using Newton iteration method with measured pH and literature equilibrium constants. In model calculation, structural parameters such as the coordination number, interatomic distance and Debye-Waller factor were given through model calculation. The B-O(H2O) distance was determined to be ∼0.37 nm with the hydration number of ∼7.8 for B(OH)4-. The Cs-B distance of the contact ions CsB(OH)40 was measured to be ∼0.46 nm with interaction number of ∼0.77. The interaction distances and coordination number for the first shell and the second shell of Cs-O(W) are ∼0.325 nm, ∼0.517 nm and ∼8.0, ∼11, respectively. Five low-energy configurations of [Cs(H2O)8]+ were given with DFT calculation, including the first and the second hydration shell, and the most stable eight-coordinated one is close to the model calculation. Furthermore, the effect of concentration is discussed in the X-ray scattering analysis part, showing that hydration degree changes with the concentration. For the coordination number and distance of Cs-O(H2O) and H-bonding decrease with the increasing concentration. The coordination number of Cs-O(H2O) keep stable, and the coordination distance changes from 3.25 nm to 3.30 nm. For H-bonding, which the coordination number varies from 2.20 to 2.24, and the coordination distance varies from 2.76 nm to 2.78 nm with the decreasing concentration.

Optimization of a dual mode Rowland mount spectrometer used in the 120-950 nm wavelength range

NASA Astrophysics Data System (ADS)

McDowell, M. W.; Bouwer, H. K.

In a recent article, several configurations were described whereby a Rowland mount spectrometer could be modified to cover a wavelength range of 120-950 nm. In one of these configurations, large additional image aberration is introduced which severely limits the spectral resolving power. In the present article, the theoretical imaging properties of this configuration are considered and a simple method is proposed to reduce this aberration. The optimized system possesses an image quality similar to the conventional Rowland mount with the image surface slightly displaced from the Rowland circle but concentric to it.

Simultaneous Spectrophotometric Estimation of Nitazoxanide and Ofloxacin in Tablets

PubMed Central

Game, Madhuri D.; Sakarkar, D. M.

2011-01-01

Two simple, accurate and precise spectrophotometric methods have been developed for simultaneous determination of nitazoxanide and ofloxacin in tablets. Method I is Q-absorbance ratio method which involves Q-absorbance at isobestic point (306.25 nm) and max (347.5 nm) of nitazoxanide, while method II is two wavelength method, where 244.6 nm and 273.0 nm were selected as 1 and 2 for determination of nitazoxanide and 294.3 nm and 388.1 nm were selected as 3 and 4 for determination of ofloxacin. Both drugs obeyed the Beer's law in the concentration range 2-30 μg/ml,correlation coefficient (r2<1). Both methods were validated statistically and recovery studies were carried out to confirm the accuracy. Commercial tablet formulation was successfully analyzed using the developed methods. PMID:22131624

[Spectrophotometric determination of prodigiozan in ampule solutions].

PubMed

Shchedrina, L E; Brutko, L I; Rastunova, G A; Shcherbakova, E G

1984-06-01

Based on a study of the absorption properties of prodigiosan it has been shown that its UV absorption spectrum is characterized by an arm at 250-260 nm with an inflection point at 260 nm. The concentration ranges within which the optical density of prodigiosan solution obeyed the Bouguer-Lambert-Beer law were measured. This allowed the development of a quantitative spectrophotometric method for determination of prodigiosan in ampouled solutions.

Photoluminescence properties of anodic aluminum oxide formed in a mixture of ammonium fluoride and oxalic acid

NASA Astrophysics Data System (ADS)

Li, Shou-Yi; Wang, Jian; Li, Yan

2017-06-01

Highly ordered anodic aluminum oxide (AAO) membranes are fabricated electrochemically in an electrolyte mixture with various concentrations of C2H2O4 or NH4F. Photoluminescence (PL) properties of AAO membranes have been investigated before and after annealing in the range from 300°C to 650°C. X-ray diffraction reveals the amorphous nature of AAO membranes. Energy dispersive spectroscopy indicates the presence of fluorine species incorporated in oxide membranes during the anodizing. PL measurements show a strong PL band in the wavelength range of 350 to 550 nm. With the increase of the concentration of the NH4F or C2H2O4 in the electrolyte mixture, the peak positions of the PL bands have a blueshift or redshift and the intensities have a maximum value. As indicated by the PL excitation spectra, there are two excitation peaks of 285 and 330 nm, which can account for the PL emission band. We have proposed that the PL originates from optical transitions in two kinds of centers that are related to oxygen vacancies, F+ (285 nm) and F (330 nm). This work is not only beneficial to further understanding of the light-emitting property of AAO membranes but also enlarges the application scope.

Optical properties of Ag nanoclusters formed by irradiation and annealing of SiO2/SiO2:Ag thin films

NASA Astrophysics Data System (ADS)

Güner, S.; Budak, S.; Gibson, B.; Ila, D.

2014-08-01

We have deposited five periodic SiO2/SiO2 + Ag multi-nano-layered films on fused silica substrates using physical vapor deposition technique. The co-deposited SiO2:Ag layers were 2.7-5 nm and SiO2 buffer layers were 1-15 nm thick. Total thickness was between 30 and 105 nm. Different concentrations of Ag, ranging from 1.5 to 50 molecular% with respect to SiO2 were deposited to determine relevant rates of nanocluster formation and occurrence of interaction between nanoclusters. Using interferometry as well as in situ thickness monitoring, we measured the thickness of the layers. The concentration of Ag in SiO2 was measured with Rutherford Backscattering Spectrometry (RBS). To nucleate Ag nanoclusters, 5 MeV cross plane Si ion bombardments were performed with fluence varying between 5 × 1014 and 1 × 1016 ions/cm2 values. Optical absorption spectra were recorded in the range of 200-900 nm in order to monitor the Ag nanocluster formation in the thin films. Thermal annealing treatment at different temperatures was applied as second method to form varying size of nanoclusters. The physical properties of formed super lattice were criticized for thermoelectric applications.

Sensitive fluorescence detection of mercury(ii) in aqueous solution by the fluorescence quenching effect of MoS2 with DNA functionalized carbon dots.

PubMed

Srinivasan, K; Subramanian, K; Murugan, K; Dinakaran, K

2016-10-24

A rapid and sensitive fluorescent sensor based on the MoS 2 nanosheet/DNA/carbon dot nanoassembly has been developed towards the detection of mercury(ii) present in environmental samples. Bio-carbon dots (CDs) having strong fluorescence maxima at 451 nm were synthesized via one-step treatment with honey under low temperature carbonization. These CDs were nearly spherical with good size distribution and excellent monodispersity, and the average sizes of CD were around 2-4 nm as evidenced from transmission electron microscopy. The conjugation of DNA strands on the surface of the carbon dots provided an efficient fluorescent probe. The fluorescence of the MoS 2 nanosheet/DNA/carbon dot nanoassembly enhanced gradually with the increase in the concentration of Hg 2+ ions and the detection limit was found to be 1.02 nM. Furthermore, the fluorescence intensity was found to be linear with the concentration of Hg 2+ ions in the range from 0 to 10 nM and their respective coefficient of determination was found to be 0.93676 and 0.98178. The present MoS 2 nanosheet/DNA/carbon dot nanoassembly is highly selective toward Hg 2+ ions over a wide range of metal ions tested.

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

Avtaeva, S. V., E-mail: s_avtaeva@mail.ru; Sosnin, E. A.; Saghi, B.

The influence of the chlorine concentration on the radiation efficiency of coaxial exciplex lamps (excilamps) excited by a dielectric barrier discharge (DBD) in binary Xe-Cl{sub 2} mixtures at pressures of 240–250 Torr is investigated experimentally and theoretically. The experiments were carried out at Cl{sub 2} concentrations in the range of 0.01–1%. The DBD characteristics were calculated in the framework of a one-dimensional hydrodynamic model at Cl{sub 2} concentrations in the range of 0.1–5%. It is found that the radiation intensities of the emission bands of Xe*{sub 2}(172 nm) and XeCl* (308 nm) are comparable when the chlorine concentration in themore » mixture is in the range of 0.01–0.1%. In this case, in the mixture, the radiation intensity of the Xe*{sub 2} molecule rapidly decreases with increasing Cl{sub 2} concentration and, at a chlorine concentration of ≥0.2%, the radiation of the B → X band of XeCl* molecules with a peak at 308 nm dominates in the discharge radiation. The radiation efficiency of this band reaches its maximum value at chlorine concentrations in the range of 0.4–0.5%. The calculated efficiencies of DBD radiation exceed those obtained experimentally. This is due to limitations of the one-dimensional model, which assumes the discharge to be uniform in the transverse direction, whereas the actual excilamp discharge is highly inhomogeneous. The influence of the chlorine concentration on the properties of the DBD plasma in binary Xe-Cl{sub 2} mixtures is studied numerically. It is shown that an increase in the Cl{sub 2} concentration in the mixture leads to the attachment of electrons to chlorine atoms and a decrease in the electron density and discharge conductivity. As a result, the electric field and the voltage drop across the discharge gap increase, which, in turn, leads to an increase in the average electron energy and the probability of dissociation of Cl{sub 2} molecules and ionization of Xe atoms and Cl{sub 2} molecules. The total energy deposited in the discharge rises with increasing chlorine concentration due to an increase in the power spent on the heating of positive and negative ions. The power dissipated by electrons decreases with increasing chlorine concentration in the working mixture. Recommendations on the choice of the chlorine content in the mixture for reducing the intensity of VUV radiation of the second continuum of the Xe*{sub 2} excimer without a substantial decrease in the excilamp efficiency are formulated.« less

Measurement of refractive index of hemoglobin in the visible/NIR spectral range

NASA Astrophysics Data System (ADS)

Lazareva, Ekaterina N.; Tuchin, Valery V.

2018-03-01

This study is focused on the measurements of the refractive index of hemoglobin solutions in the visible/near-infrared (NIR) spectral range at room temperature for characteristic laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 930, 1100, 1300, and 1550 nm. Measurements were performed using the multiwavelength Abbe refractometer. Aqua hemoglobin solutions of different concentrations obtained from human whole blood were investigated. The specific increment of refractive index on hemoglobin concentration and the Sellmeier coefficients were calculated.

Crustacean zooplankton release copious amounts of dissolved organic matter as taurine in the ocean.

PubMed

Clifford, Elisabeth L; Hansell, Dennis A; Varela, Marta M; Nieto-Cid, Mar; Herndl, Gerhard J; Sintes, Eva

2017-11-01

Taurine (Tau), an amino acid-like compound, is present in almost all marine metazoans including crustacean zooplankton. It plays an important physiological role in these organisms and is released into the ambient water throughout their life cycle. However, limited information is available on the release rates by marine organisms, the concentrations and turnover of Tau in the ocean. We determined dissolved free Tau concentrations throughout the water column and its release by abundant crustacean mesozooplankton at two open ocean sites (Gulf of Alaska and North Atlantic). At both locations, the concentrations of dissolved free Tau were in the low nM range (up to 15.7 nM) in epipelagic waters, declining sharply in the mesopelagic to about 0.2 nM and remaining fairly stable throughout the bathypelagic waters. Pacific amphipod-copepod assemblages exhibited lower dissolved free Tau release rates per unit biomass (0.8 ± 0.4 μmol g -1 C-biomass h -1 ) than Atlantic copepods (ranging between 1.3 ± 0.4 μmol g -1 C-biomass h -1 and 9.5 ± 2.1 μmol g -1 C-biomass h -1 ), in agreement with the well-documented inverse relationship between biomass-normalized excretion rates and body size. Our results indicate that crustacean zooplankton might contribute significantly to the dissolved organic matter flux in marine ecosystems via dissolved free Tau release. Based on the release rates and assuming steady state dissolved free Tau concentrations, turnover times of dissolved free Tau range from 0.05 d to 2.3 d in the upper water column and are therefore similar to those of dissolved free amino acids. This rapid turnover indicates that dissolved free Tau is efficiently consumed in oceanic waters, most likely by heterotrophic bacteria.

Comparison of the DiSCmini aerosol monitor to a handheld condensation particle counter and a scanning mobility particle sizer for submicrometer sodium chloride and metal aerosols

PubMed Central

Mills, Jessica B.; Park, Jae Hong; Peters, Thomas M.

2016-01-01

We evaluated the robust, lightweight DiSCmini (DM) aerosol monitor for its ability to measure the concentration and mean diameter of submicrometer aerosols. Tests were conducted with monodispersed and polydispersed aerosols composed of two particle types (sodium chloride, NaCl, and spark generated metal particles, which simulate particles found in welding fume) at three different steady-state concentration ranges (Low, <103; Medium, 103–104; and High, >104 particles/cm3). Particle number concentration, lung deposited surface area (LDSA) concentration, and mean size measured with the DM were compared to those measured with reference instruments, a scanning mobility particle sizer (SMPS) and a handheld condensation particle counter (CPC). Particle number concentrations measured with the DM were within 21% of those measured by reference instruments for polydisperse aerosols. Poorer agreement was observed for monodispersed aerosols (±35% for most tests and +130% for 300-nm NaCl). LDSA concentrations measured by the DM were 96% to 155% of those estimated with the SMPS. The geometric mean diameters measured with the DM were within 30% of those measured with the SMPS for monodispersed aerosols and within 25% for polydispersed aerosols (except for the case when the aerosol contained a substantial number of particles larger than 300 nm). The accuracy of the DM is reasonable for particles smaller than 300 nm but caution should be exercised when particles larger than 300 nm are present. PMID:23473056

Application of derivative ratio spectrophotometry for determination of β-carotene and astaxanthin from Phaffia rhodozyma extract*

PubMed Central

Ni, Hui; He, Guo-qing; Ruan, Hui; Chen, Qi-he; Chen, Feng

2005-01-01

A derivative ratio spectrophotometric method was used for the simultaneous determination of β-carotene and astaxanthin produced from Phaffia rhodozyma. Absorbencies of a series of the standard carotenoids in the range of 441 nm to 490 nm demonstrated that their absorptive spectra accorded with Beer’s law and that the additivity when the concentrations of β-carotene and astaxanthin and their mixture were within the range of 0 to 5 µg/ml, 0 to 6 µg/ml, and 0 to 6 µg/ml, respectively. When the wavelength interval (Δλ) at 2 nm was selected to calculate the first derivative ratio spectra values, the first derivative amplitudes at 461 nm and 466 nm were suitable for quantitatively determining β-carotene and astaxanthin, respectively. Effect of divisor on derivative ratio spectra could be neglected; any concentration used as divisor in range of 1.0 to 4.0 µg/ml is ideal for calculating the derivative ratio spectra values of the two carotenoids. Calibration graphs were established for β-carotene within 0–6.0 µg/ml and for astaxanthin within 0–5.0 µg/ml with their corresponding regressive equations in: y=−0.0082x−0.0002 and y=0.0146x−0.0006, respectively. R-square values in excess of 0.999 indicated the good linearity of the calibration graphs. Sample recovery rates were found satisfactory (>99%) with relative standard deviations (RSD) of less than 5%. This method was successfully applied to simultaneous determination of β-carotene and astaxanthin in the laboratory-prepared mixtures and the extract from the Phaffia rhodozyma culture. PMID:15909336

Determination of tramadol hydrochloride in ampoule dosage forms by using UV spectrophotometric and HPLC-DAD methods in methanol and water media.

PubMed

Küçük, Aysel; Kadioğlu, Yücel

2005-02-01

Two newly developed simple and sensitive methods for determination of tramadol hydrochloride in ampoule dosage forms were described and validated. Measurements for spectrophotometric method were performed using UV-Vis Spectrophotometer in ranges of 200-400 nm. The solutions of standard and the samples were prepared in methanol and water media and the UV absorption spectrums of tramadol were monitored with maximum absorptions at 275 and 271 nm for both mediums, respectively. The standard calibration curves of tramadol were constructed by plotting absorbance vs. concentration in the concentration range with the final dilution of 10-100 microg ml-1. Reversed phase chromatography for HPLC method was conducted using a Phenomenex Bondclone C18 column with an isocratic mobile phase consisting of 25% acetonitrile in 75% 0.01 M phosphate buffer (pH 3). The effluent was monitored on a DAD detector at 218 nm. Linear response (r>0.99) was observed over the range of 0.5-40 microg ml-1 for methanol and water and run on six different occasions. The methods were applied successfully to pharmaceutical ampoule forms, but also for comparison in two different solvent media. Besides, it was completely validated and proven to be rugged.

Enhanced spectrophotometric determination of two antihyperlipidemic mixtures containing ezetimibe in pharmaceutical preparations.

PubMed

Maher, Hadir M; Youssef, Rasha M; Hassan, Ekram M; El-Kimary, Eman I; Barary, Magda A

2011-02-01

Two spectrophotometric methods are presented for the simultaneous determination of ezetimibe/simvastatin and ezetimibe/atorvastatin binary mixtures in combined pharmaceutical dosage forms without prior separation. The first is the derivative ratio method where the amplitudes of the first derivative of the ratio spectra ((1) DD) at 299.5 and 242.5 nm were found to be linear with ezetimibe and simvastatin concentrations in the ranges 0.5-20 µgml(-1) and 1-40 µgml(-1) , respectively, whereas the amplitudes of the first derivative of the ratio spectra ((1) DD) at 289.5 and 288 nm were selected to determine ezetimibe and atorvastatin in the concentration ranges 5-50 µgml(-1) and 1-40 µgml(-1) , respectively. The second is the H-point standard additions method; absorbances at the two pairs of wavelengths, 228 and 242 nm or 238 and 248 nm, were monitored while adding standard solutions of ezetimibe or simvastatin, respectively. For the analysis of ezetimibe/atorvastatin mixture, absorbance values at 226 and 248 nm or 212 and 272 nm were monitored while adding standard solutions of ezetimibe or atorvastatin, respectively. Moreover, differential spectrophotometry was applied for the determination of ezetimibe in the two mixtures without any interference from the co-existing drug. This was performed by measurement of the difference absorptivities (ΔA) of ezetimibe in 0.07 M 30% methanolic NaOH relative to that of an equimolar solution in 0.07 M 30% methanolic HCl at 246 nm. The described methods are simple, rapid, precise and accurate for the determination of these combinations in synthetic mixtures and dosage forms. Copyright © 2010 John Wiley & Sons, Ltd.

Synthesis, energy transfer and tunable emission properties of SrSb2O6:Eu3 +, Bi3 + phosphor

NASA Astrophysics Data System (ADS)

Cao, Renping; Fu, Ting; Peng, Dedong; Cao, Chunyan; Ruan, Wen; Yu, Xiaoguang

2016-12-01

Host SrSb2O6, SrSb2O6:Bi3 +, SrSb2O6:Eu3 +, and SrSb2O6:Eu3 +, Bi3 + phosphors are synthesized by solid state reaction method in air. Host SrSb2O6 with excitation 254 nm shows weak green-yellow emission in the range of 320-780 nm due to Sb5 + → O2- transition. SrSb2O6:Bi3 + phosphor with excitation 365 nm emits green light within the range 400-650 nm owing to the 3P1 → 1S0 transition of Bi3 + ion. SrSb2O6:Eu3 + phosphor with excitation 254 nm exhibits a systematically varied hue from green to orange-red light by increasing Eu3 + concentration from 0 to 7 mol%, and that with excitation 394 nm only shows orange-red light. The optimal Eu3 + concentration is 4 mol% in SrSb2O6:Eu3 + phosphor. SrSb2O6:Eu3 +, Bi3 + phosphor with excitation 254 and 394 nm emits orange-red light. Emission intensity of SrSb2O6:Eu3 + phosphor may be enhanced > 2 times by co-doping Bi3 + ion because of the fluxing agent and energy transfer roles of Bi3 + ion in SrSb2O6:Eu3 +, Bi3 + phosphor. The luminous mechanism of SrSb2O6:Eu3 +, Bi3 + phosphor is analyzed and explained by the simplified energy level diagrams of Sb2O62 - group, Bi3 + and Eu3 + ions, and energy transfer processes between them.

Complex thiolated mannose/quinone film modified on EQCM/Au electrode for recognizing specific carbohydrate-proteins.

PubMed

Zeng, Hongjuan; Yu, Junsheng; Jiang, Yadong; Zeng, Xiangqun

2014-05-15

A complex thiolated mannose (TM)/quinone functionalised polythiophene (QFPT) thin film was modified on EQCM/Au electrode for recognition of specific carbohydrate-proteins. Different lectins such as those from Sambucus nigra (elder berry), Arachis hypogaea (peanut), Ulex europaeus (gorse, furze), Triticum vulgaris and Concanavalin A (ConA) was used for probes to evaluate bio-sensing performance of the TM/QFPT film. A specific response was observed for ConA from lectins when using the TM/QFPT film as sensing material and employing either elelctrochemical or the QCM method. No response was detected between thiolated mannose and other lectins. The linear relationship between current and ConA concentration is in the range of 0.5-17.5 nM by the elelctrochemical method and the linear relationship between frequency change and ConA concentration is in the range of 0.5-4.5 nM by the QCM method. This shows that the TM/QFPT-modified EQCM biosensor presents a paralleled determination by using electrochemical and the QCM method. The elelctrochemical method of the biosensor can be applicable in a large concentration range and its frequency change can be more precise. © 2013 Published by Elsevier B.V.

The detection of food soils and cells on stainless steel using industrial methods: UV illumination and ATP bioluminescence.

PubMed

Whitehead, Kathryn A; Smith, Lindsay A; Verran, Joanna

2008-09-30

Open food contact surfaces were subjected to organic soiling to provide a source for transfer of microbial cells. Rapid industrial methods used for the detection of residual cells and soil e.g. ATP (adenosine triphosphate) bioluminescence and an ultraviolet (UV) light detection method were assessed for their ability to detect organic soils, or organic soil-cell mix on surfaces. A range of soils (complex [meat extract, fish extract, cottage cheese extract]; oils [cholesterol, fish oil, mixed fatty acids]; proteins [bovine serum albumin, fish peptones casein]; carbohydrates [glycogen, starch, lactose]); was used. Under UV, oily soils, mixed fatty acids, cholesterol and casein were detected at low concentrations, with detection levels ranging from 1% to 0.001% for different substances. Glycogen was the most difficult substance to detect at lower concentrations. Using UV wavelength bands (lambda) of 330-380 nm, 510-560 nm and 590-650 nm, wavelength bands of 330-380 nm, illuminated most of the soils well, whilst the wavelength band of 510-560 nm illuminated the fish extract, cholesterol and fatty acids; the 590-650 nm wavelength band illuminated the lactose. Soils at all concentrations were detected by the ATP bioluminescence method; the complex soils gave the highest readings. When complex soils were combined with Listeria monocytogenes Scott A or a non-pathogenic Escherichia coli O157:H7, ATP measurements increased by 1-2 logs. For UV illumination, the L. monocytogenes and cheese combination was the most intensely illuminated, with E. coli and meat the least. UV illumination is a simple well established method for detecting food soil, with little change in findings when microorganisms are included. Performance can be enhanced in certain circumstances by altering the wavelength. ATP bioluminescence is a proven system for hygienic assessment being especially useful in the presence of microorganisms rather than organic soil alone.

Mishandling and exposure of farm workers in Qatar to organophosphate pesticides.

PubMed

Shomar, Basem; Al-Saad, Khalid; Nriagu, Jerome

2014-08-01

We used a combination of subjective (questionnaire) and objective (urinary metabolites) measurements to evaluate factors that can predict the exposure of farm workers in Qatar to organophosphate pesticides and to assess whether the levels of exposure are associated with any self-reported health outcomes. The results show that pesticides were being extensively mishandled in the farms. Very few (<2%) of the farm workers knew the names of the pesticide they were using, and about one-third of the participants did not know the amount of pesticides to be applied to the crops. Nearly all (96%) of the participants had participated in mixing pesticides together before use and few (29%) used protective clothing while engaged in this operation. A significant number of participants (18%) had no knowledge that pesticides are a health hazard. At least one dialkyllphosphate (DAP) metabolite was detected in every worker. The geometric mean (GM) concentration of the dimethylalkylphosphates (DMAP) was 108 nM (range, from below the limit of detection (LOD) to 351 nM), and the GM for the diethylalkylphosphates (DEAP) was 43 nM (range, LOD-180 nM). The GM for total concentration of the metabolites (DAP) of 146 nM (maximum value estimated to be 531 nM) is below the values that have been reported for farmers in some countries, but higher than the levels in the general populations of many countries. We explored the influence of metal exposure and found consistent and negative relationships between the DAP metabolites and the concentrations of most of the trace elements in the urine of the farm workers; the negative associations were statistically significant for Cr, Mn, Fe, Ni, As, and Pb. We suspect that the negative associations are not source-dependent but may be reflective of antagonistic relationships in human metabolism of OPPs and trace metals; hence we recommend that metals should be included as co-factors in assessing the health effects of OPP exposure. Copyright © 2014 Elsevier Inc. All rights reserved.

A novel ion-exclusion chromatography-mass spectrometry method to measure concentrations and cycling rates of carbohydrates and amino sugars in freshwaters.

PubMed

Horňák, Karel; Pernthaler, Jakob

2014-10-24

The concentrations of free neutral carbohydrates and amino sugars were determined in freshwater samples of distinct matrix complexity, including meso-, eu- and dystrophic lakes and ponds, using high-performance ion-exclusion chromatography (HPIEC) coupled to mass spectrometry (MS). In contrast to other methods, our approach allowed the quantification of free neutral carbohydrates and amino sugars at low nM concentrations without derivatization, de-salting or pre-concentration. New sample preparation procedures were applied prior to injection employing syringe and hollow fiber filtration. Analytes were separated on a strong cation exchange resin under 100% aqueous conditions using 0.1% formic acid as a mobile phase. To minimize background noise in MS, analytes were detected in a multiple reaction monitoring scan mode with double ion filtering. Detection limits of carbohydrates and amino sugars ranged between 0.2 and 2nM at a signal-to-noise ratio >5. Error ranged between 1 and 12% at 0.5-500nM levels. Using a stable isotope dilution approach, both the utilization and recycling of glucose in Lake Zurich was observed. In contrast, N-acetyl-glucosamine was equally rapidly consumed but there was no visible de novo production. The simple and rapid sample preparation makes our protocol suitable for routine analyses of organic compounds in freshwater samples. Application of stable isotope tracers along with accurate measures of carbohydrate and amino sugar concentrations enables novel insights into the compound in situ dynamics. Copyright © 2014 Elsevier B.V. All rights reserved.

Pore water distributions of dissolved copper and copper-complexing ligands in estuarine and coastal marine sediments

NASA Astrophysics Data System (ADS)

Skrabal, Stephen A.; Donat, John R.; Burdige, David J.

2000-06-01

The distributions and seasonal variability of total dissolved Cu (TDCu) and Cu-complexing ligands in sediment pore waters have been investigated at two contrasting sites in the Chesapeake Bay. Two ligand classes, which differ on the basis of the conditional stability constants ( K'cond) of their Cu complexes, were detected at all depths at both sites. At the sulfidic, muddy, mid-Bay Sta. M, concentrations and values of log K'cond ranged from 390-12,500 nM and ≥7.2->8.9, respectively, for the stronger ligand class ( L1 S) and 75-6,420 nM and 6.2-7.9 for the weaker ligand class ( L2 S). At the bioturbated, sandy Sta. S in the lower Bay, respective concentrations and values of log K'cond ranged from 135-807 nM and ≥7.6-≥10.2 for L1 S and 40-1,410 nM and 6.6-9.2 for L2 S. For comparison, one pore water profile from a slope station off of the Chesapeake Bay also showed the presence of two ligand classes, with respective concentrations and values of log K'cond of 140-270 nM and 8->11 for L1 S and 30-180 nM and 7-10 for L2 S. These ligands are in large excess relative to ambient TDCu concentrations (<0.1-24.3 nM), thereby maintaining very low inorganic Cu concentrations (typically <0.1 to <100 pM) and a high degree of organic complexation (87.2->99.9%) of Cu in Bay and slope sediment pore waters. Thus, virtually all TDCu fluxing from these sediments is complexed during sediment-water exchange. A relatively small fraction of the TDCu is exchanged as inorganic species, which are widely regarded as the most bioavailable form of Cu. Higher ligand concentrations at Sta. M suggest that sulfide or organic ligands containing reduced S contribute to the pool of complexing ligands; however, the exact nature and sources of the ligands in Bay pore waters are not known. The progressive increase in conditional stability constants of the CuL 2 S complexes from the mid-Bay to the slope sediments may reflect differences in biological or chemical processes at each site, as well as differences in the type of Cu-complexing organic matter. Total ligand concentrations ( L1 S + L2 S) are 15 to >100 times higher in the upper intervals of the pore waters relative to ligand concentrations in the bottom waters of the Chesapeake Bay (30-60 nM), consistent with previous observations of fluxes of these ligands from the sediments to overlying waters. These results suggest that sediments are potentially significant sources of Cu-complexing ligands to the overlying waters of the Chesapeake Bay, and perhaps, other shallow water estuarine and coastal environments. Copper-complexing ligands released from sediment pore waters may play an important role in influencing Cu speciation in overlying waters.

Field evaluation of vegetation and noise barriers for mitigation of near-freeway air pollution under variable wind conditions

NASA Astrophysics Data System (ADS)

Lee, Eon S.; Ranasinghe, Dilhara R.; Ahangar, Faraz Enayati; Amini, Seyedmorteza; Mara, Steven; Choi, Wonsik; Paulson, Suzanne; Zhu, Yifang

2018-02-01

Traffic-related air pollutants are a significant public health concern, particularly near freeways. Previous studies have suggested either soundwall or vegetation barriers might reduce the near-freeway air pollution. This study aims to investigate the effectiveness of a combination of both soundwall and vegetation barrier for reducing ultrafine particles (UFPs, diameter ≤ 100 nm) and PM2.5 (diameter ≤ 2.5 μm) concentrations. Concurrent data collection was carried out at both upwind and downwind fixed locations approximately 10-15 m away from the edge of two major freeways in California. This study observed that the reduction of UFP and PM2.5 was generally greater with the combination barrier than with either soundwall or vegetation alone. Since there were no non-barrier sites at the study locations, the reductions reported here are all in relative terms. The soundwall barrier was more effective for reducing PM2.5 (25-53%) than UFPs (0-5%), and was most effective (51-53% for PM2.5) when the wind speed ranged between 1 and 2 m/s. Under the same range of wind speed, the vegetation barrier had little effect (0-5%) on reducing PM2.5; but was effective at reducing UFP (up to 50%). For both types of roadside barrier, decreasing wind speed resulted in greater net reduction of UFPs (i.e., total number particle concentrations; inversely proportional). This trend was observed, however, only within specific particle size ranges (i.e., diameter < 20 nm for the soundwall barrier and 12-60 nm for the vegetation barrier). Out of these size ranges, the reduction of UFP concentration was proportional to increasing wind speed. Overall findings of this study support positive effects of soundwall and vegetation barriers for near-freeway air pollution mitigation.

Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli.

PubMed

Zhang, Haoshu; Dudley, Edward G; Davidson, P Michael; Harte, Federico

2017-04-15

Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (<100 nm) at the critical lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects. IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens. Copyright © 2017 American Society for Microbiology.

Critical Concentration of Lecithin Enhances the Antimicrobial Activity of Eugenol against Escherichia coli

PubMed Central

Zhang, Haoshu; Dudley, Edward G.; Davidson, P. Michael

2017-01-01

ABSTRACT Lecithin is a natural emulsifier used in a wide range of food and nonfood applications to improve physical stability, with no known bioactive effects. In this study, the effect of lecithin on the antimicrobial performance of a constant eugenol concentration was tested against three Escherichia coli strains (C600, 0.1229, and O157:H7 strain ATCC 700728). This is the first study, to our knowledge, focusing on lecithin at concentrations below those commonly used in foods to improve the stability of oil in water emulsions (≤10 mg/100 ml). For all three cultures, significant synergistic antimicrobial effects were observed when E. coli cultures were exposed to a constant eugenol concentration (ranging from 0.043 to 0.050% [wt/wt]) together with critical lecithin concentrations ranging from 0.5 to 1 mg/100 ml. Increasing the concentration of lecithin above 1 mg/100 ml (up to 10 mg/100 ml lecithin) diminished the antibacterial effect to values similar to those with eugenol-only treatments. The formation of aggregates (<100 nm) at the critical lecithin concentration was observed using cryo-transmission electron microscopy (cryo-TEM), together with a reduction in light absorbance at 284 nm. At critically low concentrations of lecithin, the formation of nanoscale aggregates is responsible for improving eugenol antimicrobial effects. IMPORTANCE Essential oils (EOs) are effective natural antimicrobials. However, their hydrophobicity and strong aromatic character limit the use of essential oils in food systems. Emulsifiers (e.g., lecithin) increase the stability of EOs in water-based systems but fail to consistently improve antimicrobial effects. We demonstrate that lecithin, within a narrow critical concentration window, can enhance the antimicrobial properties of eugenol. This study highlights the potential bioactivity of lecithin when utilized to effectively control foodborne pathogens. PMID:28213539

A fluorescence spectroscopy study of traditional Chinese medicine Angelica

NASA Astrophysics Data System (ADS)

Zhao, Hongyan; Song, Feng; Liu, Shujing; Chen, Guiyang; Wei, Chen; Liu, Yanling; Liu, Jiadong

2013-10-01

By measuring the fluorescence spectra of Chinese medicine (CM) Angelica water solutions with different concentrations from 0.025 to 2.5 mg/mL, results showed that the fluorescence intensity was proportional to the concentration. Through fluorescence spectra of Angelica solution under different pH values, results indicated coumarin compounds were the active ingredients of Angelica. We also observed fluorescence quenching of the Angelica solution in the presence of spherical silver nanoparticles with radius of 12 nm. Keeping a certain value for the volume of the silver nanoparticles, the fluorescence intensity at 402 nm was linearly proportional to the Angelica in the range of 1-3 mg/mL.

Effect of beta-ADrenergic Agonist on Cyclic AMP Synthesis in Chicken Skeletal Muscle Cells in Culture

NASA Technical Reports Server (NTRS)

Young, R. B.; Bridge, K. Y.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Several beta-adrenergic receptor (bAR) agonists are known to cause hypertrophy of skeletal muscle tissue. Because it seems logical that these agonists exert their action on muscle through stimulation of cAMP synthesis, five bAR agonists encompassing a range in activity from strong to weak were evaluated for their ability to stimulate cAMP accumulation in embryonic chicken skeletal muscle cells in culture. Two strong agonists (epinephrine and isoproterenol), one moderate agonist (albuterol), and two weak agonists known to cause hypertrophy in animals (clenbuterol and cimaterol) were studied. Dose response curves were determined over six orders of magnitude in concentration for each agonist, and values were determined for their maximum stimulation of cAMP synthesis rate (Bmax) and the agonist concentration at which 50% stimulation of cAMP synthesis (EC50) occurred. Bmax values decreased in the following order: isoproterenol, epinephrine, albuterol, cimaterol, clenbuterol. Cimaterol and clenbuterol at their Bmax levels were approximately 15-fold weaker than isoproterenol in stimulating the rate of cAMP synthesis. In addition, the EC50 values for isoproterenol, cimaterol, clenbuterol, epinephrine, and albuterol were 360 nM, 630 nM, 900 nM, 2,470 nM, and 3,650 nM, respectively. Finally, dose response curves show that the concentrations of cimaterol and clenbuterol in culture media at concentrations known to cause significant muscle hypertrophy in animals had no detectable effect on stimulation of CAMP accumulation in chicken skeletal muscle cells.

Scintillation properties of phosphate-borate-fluoride glass doped with Tb3+/Pr3+

NASA Astrophysics Data System (ADS)

Valiev, D.; Stepanov, S.; Polisadova, E.; Yao, G.

2018-06-01

Scintillation glass doped with Tb3+ and Pr3+ ions with different concentrations were prepared by the melt-quenching method. Optical, photoluminescence and decay kinetic characteristics of the pulse cathodoluminescence (PCL) were investigated. It was shown that the absorption coefficient of the induced absorption in the visible range of the spectrum decreases significantly with the increase of the Pr2O3 content starting from 0.2 to 1 wt%. There was the difference in the luminescence spectra of the glass at a selective and non-selective type of excitation. The "green" emission (λem= 542 nm, 5D4→7F5 radiative transition of Tb3+ ions) was excited an electron beam. The "red" emission (λem= 600 nm, 3P0→3H6 radiative transition of Pr3+ ion) was observed under selective excitation action (λexc= 450 nm). It was demonstrated that decreasing of intensity the main bands of Tb3+ ions at 487, 544, 622 nm connected with increases of concentration Pr3+ ions. The luminescence decay time of terbium ions at 487, 544, 622 nm emission bands depend on Pr3+ concentration. The tendency of reducing the luminescence decay time in the main luminescence bands of Tb3+ ions at increasing the Pr3+ concentration was presented. The results showed that Tb3+/ Pr3+ co-doped phosphate-borate-fluoride glasses are promising non-crystalline scintillation materials.

Origin and Quenching of Novel ultraviolet and blue emission in NdGaO3: Concept of Super-Hydrogenic Dopants.

PubMed

Ghosh, Siddhartha; Saha, Surajit; Liu, Zhiqi; Motapothula, M; Patra, Abhijeet; Yakovlev, Nikolai; Cai, Yao; Prakash, Saurav; Huang, Xiao Hu; Tay, Chuan Beng; Cong, Chun Xiao; Bhatt, Thirumaleshwara; Dolmanan, Surani B; Chen, Jianqiang; Lü, Weiming; Huang, Zhen; Tripathy, Sudhiranjan; Chua, Soo Jin; Yu, Ting; Asta, Mark; Ariando, A; Venkatesan, T

2016-11-03

In this study we report the existence of novel ultraviolet (UV) and blue emission in rare-earth based perovskite NdGaO 3 (NGO) and the systematic quench of the NGO photoluminescence (PL) by Ce doping. Study of room temperature PL was performed in both single-crystal and polycrystalline NGO (substrates and pellets) respectively. Several NGO pellets were prepared with varying Ce concentration and their room temperature PL was studied using 325 nm laser. It was found that the PL intensity shows a systematic quench with increasing Ce concentration. XPS measurements indicated that nearly 50% of Ce atoms are in the 4+ state. The PL quench was attributed to the novel concept of super hydrogenic dopant (SHD)", where each Ce 4+ ion contributes an electron which forms a super hydrogenic atom with an enhanced Bohr radius, due to the large dielectric constant of the host. Based on the critical Ce concentration for complete quenching this SHD radius was estimated to be within a range of 0.85 nm and 1.15 nm whereas the predicted theoretical value of SHD radius for NdGaO3 is ~1.01 nm.

Natural marine bacteria as model organisms for the hazard-assessment of consumer products containing silver nanoparticles.

PubMed

Echavarri-Bravo, Virginia; Paterson, Lynn; Aspray, Thomas J; Porter, Joanne S; Winson, Michael K; Hartl, Mark G J

2017-09-01

Scarce information is available regarding the fate and toxicology of engineered silver nanoparticles (AgNPs) in the marine environment, especially when compared to other environmental compartments. Hence, the antibacterial activity of the NM-300 AgNPs (OECD programme) and a household product containing colloidal AgNPs (Mesosilver) was investigated using marine bacteria, pure cultures and natural mixed populations (microcosm approach). Bacterial susceptibility to AgNPs was species-specific, with Gram negative bacteria being more resistant than the Gram positive species (NM-300 concentration used ranged between 0.062 and 1.5 mg L -1 ), and the Mesosilver product was more toxic than the NM-300. Bacterial viability and the physiological status (O 2 uptake measured by respirometry) of the microbial community in the microcosm was negatively affected at an initial concentration of 1 mg L -1 NM-300. The high chloride concentrations in the media/seawater led to the formation of silver-chloro complexes thus enhancing AgNP toxicity. We recommend the use of natural marine bacteria as models when assessing the environmental relevant antibacterial properties of products containing nanosilver. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Understanding Fire Through Improved Technology

NASA Technical Reports Server (NTRS)

2004-01-01

Aztec(TradeMark) is the commercial name for Southwest Sciences laser. The laser has coarse tuning ranges of 10 nanometers (nm) to 30 nm at wavelengths ranging from 630 nm to 2,300 nm, making it the only commercially available external cavity diode laser with wavelengths beyond 1,650 nm. The laser's high-speed tuning in both coarse and fine wavelength regimes allows for increased trace gas detection. With the automated coarse tuning option, the Aztec sweeps through its wavelength range in less than 1 millisecond. While some diode lasers can only detect one type, or species, of a trace gas, the Aztec's broad wavelength tuning provides access to multiple trace gas species. The Aztec has a wide range of applications for both NASA and commercial users, from protecting astronauts in space to improving combustion processes on Earth. It may serve as a new tool for planetary exploration, as it can detect a wide range of multiple gas species in planetary atmospheres. The laser could optically detect gaseous indicators of incipient fires on the International Space Station and Space Shuttle, as well as detect low concentrations of potentially toxic gases in spacecraft crew habitats. The laser could also provide more accurate fire detection in aircraft cargo compartments. Since the Aztec can detect several gases that only evolve during an actual fire, its implementation could reduce the large number of commercial aircraft landings that currently occur due to false alarms. Other applications include environmental and industrial process monitoring.

Development and validation of an UPLC-MS/MS method for the quantification of irinotecan, SN-38 and SN-38 glucuronide in plasma, urine, feces, liver and kidney: Application to a pharmacokinetic study of irinotecan in rats.

PubMed

Basu, Sumit; Zeng, Min; Yin, Taijun; Gao, Song; Hu, Ming

2016-03-15

The objective of this research is to develop and validate a sensitive and reproducible UPLC-MS/MS method to quantify irinotecan, its active metabolite SN-38 and SN-38 glucuronide (phase II metabolite of SN-38) simultaneously in different bio-matrices (plasma, urine, feces), tissues (liver and kidney) and to use the method to investigate its pharmacokinetic behavior in rats. Irinotecan, SN-38 and SN-38 glucuronide has been resolved and separated by C18 column using acetonitrile and 0.1% formic acid in water used as the mobile phases. Triple quadruple mass spectrometer using multiple reaction monitoring (MRM) with positive scan mode were employed to perform mass analysis. The results showed that the linear response range of irinotecan and SN-38 in plasma, feces, liver and kidney is 4.88-10000 nM, 39-5000 nM, 48.8-6250 nM and 48.8-6250 nM, respectively (R(2)>0.99). In case of SN-38 glucuronide, the standard curves were linear in the concentration range of 6.25-2000 nM, 4.88-1250 nM, 9.8-1250 nM and 9.8-1250 nM in plasma, feces, liver and kidney homogenates, respectively. The lower limit of detection (LLOD) of irinotecan, SN-38 and SN-38 glucuronide was determined to be less than 25 nM in all bio-matrices as well as tissue homogenates. Recoveries of irinotecan, SN-38 and SN-38 glucuronide at three different concentrations (low, medium and high) were not less than 85% at three different concentrations in plasma and feces. The percentage matrix factors in different bio-matrices and tissues were within 20%. The UPLC-MS/MS method was validated with intra-day and inter-day precision of less than 15% in plasma, feces, liver and kidney. Owing to the high sensitivity of this method, only 20 μl of plasma, urine and homogenates of liver, kidney and feces is needed. The validated method has been successfully employed for pharmacokinetic evaluation of irinotecan in male wistar rats to quantify irinotecan, SN-38 and SN-38 glucuronide in plasma, feces, and urine samples. Published by Elsevier B.V.

Development and validation of an UPLC-MS/MS method for the quantification of irinotecan, SN 38 and SN-38 glucuronide in plasma, urine, feces, liver and kidney: Application to a pharmacokinetic study of irinotecan in rats

PubMed Central

Basu, Sumit; Zeng, Min; Yin, Taijun; Gao, Song; Hu, Ming

2016-01-01

The objective of this research is to develop and validate a sensitive and reproducible UPLC-MS/MS method to quantify irinotecan, its active metabolite SN-38 and SN-38 glucuronide (phase II metabolite of SN-38) simultaneously in different bio-matrices (plasma, urine, feces), tissues (liver and kidney) and to use the method to investigate its pharmacokinetic behavior in rats. Irinotecan, SN-38 and SN-38 glucuronide has been resolved and separated by C18 column using acetonitrile and 0.1% formic acid in water used as the mobile phases. Triple quadruple mass spectrometer using multiple reaction monitoring (MRM) with positive scan mode were employed to perform mass analysis. The results showed that the linear response range of irinotecan and SN-38 in plasma, feces, liver and kidney is 4.88 –10000 nM, 39 – 5000 nM, 48.8 –6250 nM and 48.8 – 6250 nM, respectively (R2 > 0.99). In case of SN-38 glucuronide, the standard curves were linear in the concentration range of 6.25 – 2000 nM, 4.88 – 1250 nM, 9.8 – 1250 nM and 9.8 – 1250 nM in plasma, feces, liver and kidney homogenates, respectively. The lower limit of detection (LLOD) of irinotecan, SN-38 and SN-38 glucuronide was determined to be less than 25 nM in all bio-matrices as well as tissue homogenates. Recoveries of irinotecan, SN-38 and SN-38 glucuronide at three different concentrations (low, medium and high) were not less than 85% at three different concentrations in plasma and feces. The percentage matrix factors in different bio-matrices and tissues were within 20%. The UPLC-MS/MS method was validated with intra-day and inter-day precision of less than 15% in plasma, feces, liver and kidney. Owing to the high sensitivity of this method, only 20 µl of plasma, urine and homogenates of liver, kidney and feces is needed. The validated method has been successfully employed for pharmacokinetic evaluation of irinotecan in male wistar rats to quantify irinotecan, SN-38 and SN-38 glucuronide in plasma, feces, and urine samples. PMID:26894853

The effect of gold nanoparticles modified electrode on the glucose sensing performance

NASA Astrophysics Data System (ADS)

Zulkifli, Zulfa Aiza; Ridhuan, Nur Syafinaz; Nor, Noorhashimah Mohamad; Zakaria, Nor Dyana; Razak, Khairunisak Abdul

2017-07-01

In this work, 20 nm, 30 nm, 40 nm, 50 nm and 60 nm colloidal gold nanoparticles (AuNPs) were synthesized using the seeding growth method. AuNPs produced had spherical shape with uniform size. The AuNPs also are well dispersed in colloidal form that was proven by low polydispersity index. The produced AuNPs were used to modify electrode for glucose sensor. The produced AuNPs were deposited on indium tin oxide substrate (ITO), followed by immobilization of glucose oxidase (GOx) on it. After that, Nafion was deposited on the GOx/AuNPs/ITO. Electrooxidation of glucose with AuNPs-modified electrode was examined by cyclic voltammeter (CV) in 15 mM glucose mixed with 0.01 M PBS. The optimum size of AuNPs was 30 nm with optical density 3.0. AuNPs were successfully immobilized with glucose oxidase (GOx) and proved to work well as a glucose sensor. Based on the high electrocatalytic activity of Nafion/GOx/AuNPs/ITO, the sensitivity of the glucose sensors was further examined by varying the concentration of glucose solution from 2 mM to 20 mM in 0.01 M phosphate buffer solution (PBS) solution. Good linear relationship was observed between the catalytic current and glucose concentration in the range of 2 mM to 20 mM. The sensitivity of the Nafion/GOx/AuNPs/ITO electrode calculated from the slope of linear square calibration was 0.909 µA mM-1 cm-2 that is comparable with other published work. The linear fitting to the experimental data gives R-square of 0.991 at 0.9 V and a detection limit of 2.03 mM. This detection range is sufficient to be medically useful in monitoring human blood glucose level in which the normal blood glucose level is in the range of 4.4 to 6.6 mM and diabetic blood glucose level is above 7 mM.

Fluorescence Correlation Spectroscopy at Micromolar Concentrations without Optical Nanoconfinement

DOE PAGES

Laurence, Ted A.; Ly, Sonny; Bourguet, Feliza; ...

2014-08-14

Fluorescence correlation spectroscopy (FCS) is an important technique for studying biochemical interactions dynamically that may be used in vitro and in cell-based studies. It is generally claimed that FCS may only be used at nM concentrations. We show that this general consensus is incorrect and that the limitation to nM concentrations is not fundamental but due to detector limits as well as laser fluctuations. With a high count rate detector system and applying laser fluctuation corrections, we demonstrate FCS measurements up to 38 μM with the same signal-to-noise as at lower concentrations. Optical nanoconfinement approaches previously used to increase themore » concentration range of FCS are not necessary, and further increases above 38 μM may be expected using detectors and detector arrays with higher saturation rates and better laser fluctuation corrections. This approach greatly widens the possibilities of dynamic measurements of biochemical interactions using FCS at physiological concentrations.« less

Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

PubMed

Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

2013-11-26

The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (μ) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ∼2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of μ on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ∼3.5 nm thick layer (mean dissociation pK ∼ 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ∼ 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film.

Molybdenum Availability Is Key to Nitrate Removal in Contaminated Groundwater Environments

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

Thorgersen, Michael P.; Lancaster, W. Andrew; Vaccaro, Brian J.

2015-05-15

The concentrations of molybdenum (Mo) and 25 other metals were measured in groundwater samples from 80 wells on the Oak Ridge Reservation (ORR) (Oak Ridge, TN), many of which are contaminated with nitrate, as well as uranium and various other metals. Moreover, the concentrations of nitrate and uranium were in the ranges of 0.1 μM to 230 mM and <0.2 nM to 580 μM, respectively. Most metals examined had significantly greater median concentrations in a subset of wells that were highly contaminated with uranium (≥126 nM). They included cadmium, manganese, and cobalt, which were 1,300- to 2,700-fold higher. A notablemore » exception, however, was Mo, which had a lower median concentration in the uranium-contaminated wells. This is significant, because Mo is essential in the dissimilatory nitrate reduction branch of the global nitrogen cycle. It is required at the catalytic site of nitrate reductase, the enzyme that reduces nitrate to nitrite. Furthermore, more than 85% of the groundwater samples contained less than 10 nM Mo, whereas concentrations of 10 to 100 nM Mo were required for efficient growth by nitrate reduction for twoPseudomonasstrains isolated from ORR wells and by a model denitrifier,Pseudomonas stutzeriRCH2. Higher concentrations of Mo tended to inhibit the growth of these strains due to the accumulation of toxic concentrations of nitrite, and this effect was exacerbated at high nitrate concentrations. The relevance of these results to a Mo-based nitrate removal strategy and the potential community-driving role that Mo plays in contaminated environments are discussed.« less

Heating efficiency dependency on size and morphology of magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Parekh, Kinnari; Parmar, Harshida; Sharma, Vinay; Ramanujan, R. V.

2018-04-01

Different size magnetite nanoparticles ranging from superparamagnetic (9 nm) to single domain (27 nm) and multi domain (53 nm) were synthesized using chemical route. Morphology of these particles as seen from TEM images indicates shape change from spherical to cubic with the growth of particles. The saturation magnetization (σs) and Specific Loss Power (SLP) showed maximum for single domain size, 72 emu/g and 102 W/g, respectively then those of multi domain size particles. These samples show higher SLP at relatively low concentration, low frequency and low amplitude compared to samples prepared by other routes.

Infrared Luminescence at 1010 nm and 1500 nm in LiNbO3:Er3+ Excitted by Short Pulse Radiation at 980 nm

NASA Astrophysics Data System (ADS)

Kokanyan, E. P.; Demirkhanyan, G. G.; Steveler, E.; Rinnert, H.; Aillerie, M.

Luminescence of LiNbO3:Er3+ crystal at a wavelength of 1010 nm and 1500 nm under pulsed excitation of different power at a wavelength of 980 nm are experimentally and theoretically studied. It is revealed, that the main part of the absorbed energy gives rise to the luminescence at 1500 nm. Considered concentrations of Er3+ impurity ions allow to exclude cooperative processes in the impurity subsystem. The experimental results are interpreted in the framework of a three electronic levels system, assuming that the population of the higher lasing level 4I13/2 in the crystal under study is caused by relaxation processes from the excited level. It is shown that for obtaining of a laser radiation at about 1500 nm one can effectively use a pulse-pumping at 980 nm with a power density in a range of 50 ÷ 60 MW/cm2.

Mechanisms of optical losses in the 5D4 and 5D3 levels in Tb3+ doped low silica calcium aluminosilicate glasses

NASA Astrophysics Data System (ADS)

dos Santos, J. F. M.; Terra, I. A. A.; Astrath, N. G. C.; Guimarães, F. B.; Baesso, M. L.; Nunes, L. A. O.; Catunda, T.

2015-02-01

Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb3+-doped low silica calcium aluminosilicate glasses are analyzed for UV (λexc = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb3+ concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5-15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb3+ concentrations. Cooperative upconversion from a pair of excited ions (5D3:5D3 or 5D3:5D4) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.

Spectrophotometric and spectrofluorimetric methods for determination of certain biologically active phenolic drugs in their bulk powders and different pharmaceutical formulations.

PubMed

Omar, Mahmoud A; Badr El-Din, Kalid M; Salem, Hesham; Abdelmageed, Osama H

2018-03-05

Two simple and sensitive spectrophotometric and spectrofluorimetric methods for the determination of terbutaline sulfate, fenoterol hydrobromide, etilefrine hydrochloride, isoxsuprine hydrochloride, ethamsylate, doxycycline hyclate have been developed. Both methods were based on the oxidation of the cited drugs with cerium (IV) in acid medium. The spectrophotometric method was based on measurement of the absorbance difference (ΔA), which represents the excess cerium (IV), at 317nm for each drug. On the other hand, the spectrofluorimetric method was based on measurement of the fluorescent of the produced cerium (III) at emission wavelength 354nm (λ excitation =255nm) for the concentrations studied for each drug. For both methods, the variables affecting the reactions were carefully investigated and the conditions were optimized. Linear relationships were found between either ΔA or the fluorescent of the produced cerium (III) values and the concentration of the studied drugs in a general concentration range of 2.0-24.0μgmL -1 , 20.0-24.0ngmL -1 with good correlation coefficients in the following range 0.9990-0.9999, 0.9990-0.9993 for spectrophotometric and spectrofluorimetric methods respectively. The limits of detection and quantitation of spectrophotometric method were found in general concentration range 0.190-0.787 and 0.634-2.624μgmL -1 respectively. For spectrofluorimetric method, the limits of detection and quantitation were found in general concentration range 4.77-9.52 and 15.91-31.74ngmL -1 respectively. The stoichiometry of the reaction was determined, and the reactions pathways were postulated. The analytical performance of the methods, in terms of accuracy and precision, were statistically validated and the results obtained were satisfactory. The methods have been successfully applied to the determination of the cited drugs in their commercial pharmaceutical formulations. Statistical comparison of the results with the reference methods showed excellent agreement and proved that no significant difference in the accuracy and precision. Copyright © 2017 Elsevier B.V. All rights reserved.

Electrical properties of tin-doped zinc oxide nanostructures doped at different dopant concentrations

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

Nasir, M. F., E-mail: babaibaik2002@yahoo.com; Zainol, M. N., E-mail: nizarzainol@yahoo.com; Hannas, M., E-mail: mhannas@gmail.com

This project has been focused on the electrical and optical properties respectively on the effect of Tin doped zinc oxide (ZnO) thin films at different dopant concentrations. These thin films were doped with different Sn dopant concentrations at 1 at%, 2 at%, 3 at%, 4 at% and 5 at% was selected as the parameter to optimize the thin films quality while the annealing temperature is fixed 500 °C. Sn doped ZnO solutions were deposited onto the glass substrates using sol-gel spin coating method. This project was involved with three phases, which are thin films preparation, deposition and characterization. The thinmore » films were characterized using Current Voltage (I-V) measurement and ultraviolet-visible-near-infrared (UV-vis-NIR) spectrophotometer (Perkin Elmer Lambda 750) for electrical properties and optical properties. The electrical properties show that the resistivity is the lowest at 4 at% Sn doping concentration with the value 3.08 × 10{sup 3} Ωcm{sup −1}. The absorption coefficient spectrum obtained shows all films exhibit very low absorption in the visible (400-800 nm) and near infrared (NIR) (>800 nm) range but exhibit high absorption in the UV range.« less

Stability indicating spectrophotometric and spectrodensitometric methods for the determination of diatrizoate sodium in presence of its degradation product

NASA Astrophysics Data System (ADS)

Abd El-Rahman, Mohamed K.; Riad, Safaa M.; Abdel Gawad, Sherif A.; Fawaz, Esraa M.; Shehata, Mostafa A.

2015-02-01

Three sensitive, selective, and precise stability indicating methods for the determination of the X-ray contrast agent, diatrizoate sodium (DTA), in the presence of its acidic degradation product (highly cytotoxic 3,5 diamino metabolite) and in pharmaceutical formulation were developed and validated. The first method is a first derivative (D1) spectrophotometric one, which allows the determination of DTA in the presence of its degradate at 231.2 nm (corresponding to zero crossing of the degradate) over a concentration range of 2-24 μg/mL with mean percentage recovery 99.95 ± 0.97%. The second method is the first derivative of the ratio spectra (DD1) by measuring the peak amplitude at 227 nm over the same concentration range as D1 spectrophotometric method, with mean percentage recovery 99.99 ± 1.15%. The third method is a TLC-densitometric one, where DTA was separated from its degradate on silica gel plates using chloroform:methanol:ammonium hydroxide (20:10:2 by volume) as a developing system. This method depends on quantitative densitometric evaluation of thin layer chromatogram of DTA at 238 nm over a concentration range of 4-20 μg/spot, with mean percentage recovery 99.88 ± 0.89%. The selectivity of the proposed methods was tested using laboratory-prepared mixtures. The proposed methods have been successfully applied to the analysis of DTA in pharmaceutical dosage forms without interference from other dosage form additives. The results were statistically compared with the official US pharmacopeial method. No significant difference for either accuracy or precision was observed.

Simultaneous determination of piracetam and vincamine by spectrophotometric and high-performance liquid chromatographic methods.

PubMed

El-Saharty, Yasser Shaker Ibrahim

2008-01-01

A mixture of piracetam and vincamine was determined by 3 different methods. The first was the determination of piracetam and vincamine using the ratio-spectra first-derivative (DD1) spectrophotometric technique at 209 and 293 nm in concentration ranges of 10-45 and 2-14 microg/mL with mean recoveries of 99.22 +/- 0.72 and 99.67 +/- 0.79%, respectively. The second method was based on the resolution of the 2 components by bivariate calibration depending on a mathematic algorithm that provides simplicity and rapidity. The method depended on quantitative evaluation of the absorbencies at 210 and 225 nm in concentration ranges of 5-45 and 2-14 microg/mL, with mean recoveries of 100.33 +/- 0.54 and 100.44 +/- 0.98% for piracetam and vincamine, respectively. The third method was reversed-phase liquid chromatography using 0.05 M potassium dihydrogen phosphate-methanol (50 + 50, v/v) as the mobile phase, with the pH adjusted to 3.5 with phosphoric acid. The eluent was monitored at 215 nm in concentration ranges of 5-100 and 2-200 microg/mL, with mean recoveries of 99.62 +/- 0.67 and 99.32 +/- 0.85% for piracetam and vincamine, respectively. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparation. The methods retained their accuracy and precision when applying the standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method.

Synthesis and characterization of nanocrystalline LaMnO3 modified BaTiO3 ferroelectric ceramics prepared by chemical route

NASA Astrophysics Data System (ADS)

Dhak, Prasanta; Adak, Mrinal Kanti; Dhak, Debasis

2016-02-01

Nanocrystalline Ba1-3xTi1-3xLa2xMn4xO3, [x = 0.006, 0.008, 0.01 and 0.05] (abbreviated hereafter as BTLM) by chemical route. The phase formation and purity were checked by X-ray diffraction (XRD) study and transmission electron microscopy (TEM). The grain morphology after sintering was studied by scanning electron microscopy (SEM). The crystallite sizes range from 21 nm to 30 nm, while the particle size ranges between 27 nm and 38 nm. The grain size 212 nm and grain density 96.8% were found to be maximum for BTLM x = 0.05 and x = 0.01, respectively. The temperature dependence of dielectric constants was found to be more diffused and the peak value of the dielectric constant was decreased and more flat with the increase of the substituent concentration. The tangent loss was found to be decreased and reached to the minimum value of 0.032 for BTLM x = 0.05. The remnant polarization Pr, was 10 μC/cm2 for BTLM x = 0.01.

Detection of Thrombin Based on Fluorescence Energy Transfer between Semiconducting Polymer Dots and BHQ-Labelled Aptamers.

PubMed

Liu, Yizhang; Jiang, Xuekai; Cao, Wenfeng; Sun, Junyong; Gao, Feng

2018-02-14

Carboxyl-functionalized semiconducting polymer dots (Pdots) were synthesized as an energy donor by the nanoprecipitation method. A black hole quenching dye (BHQ-labelled thrombin aptamers) was used as the energy acceptor, and fluorescence resonance energy transfer between the aptamers and Pdots was used for fluorescence quenching of the Pdots. The addition of thrombin restored the fluorescence intensity. Under the optimized experimental conditions, the fluorescence of the system was restored to the maximum when the concentration of thrombin reached 130 nM, with a linear range of 0-50 nM (R² = 0.990) and a detection limit of 0.33 nM. This sensor was less disturbed by impurities, showing good specificity and signal response to thrombin, with good application in actual samples. The detection of human serum showed good linearity in the range of 0-30 nM (R² = 0.997), with a detection limit of 0.56 nM and a recovery rate of 96.2-104.1%, indicating that this fluorescence sensor can be used for the detection of thrombin content in human serum.

Ultrafine particles, and PM 2.5 generated from cooking in homes

NASA Astrophysics Data System (ADS)

Wan, Man-Pun; Wu, Chi-Li; Sze To, Gin-Nam; Chan, Tsz-Chun; Chao, Christopher Y. H.

2011-11-01

Exposure to airborne particulate matters (PM) emitted during cooking can lead to adverse health effects. An understanding of the exposure to PM during cooking at home provides a foundation for the quantification of possible health risks. The concentrations of airborne particles covering the ultrafine (14.6-100 nm) and accumulation mode (100-661.2 nm) size ranges and PM 2.5 (airborne particulate matters smaller than 2.5 μm in diameter) during and after cooking activities were measured in 12 naturally ventilated, non-smoking homes in Hong Kong, covering a total of 33 cooking episodes. The monitored homes all practiced Chinese-style cooking. Cooking elevated the average number concentrations of ultrafine particles (UFPs) and accumulation mode particles (AMPs) by 10 fold from the background level in the living room and by 20-40 fold in the kitchen. PM 2.5 mass concentrations went up to the maximum average of about 160 μg m -3 in the kitchen and about 60 μg m -3 in the living room. Cooking emitted particles dispersed quickly from the kitchen to the living room indicating that the health impact is not limited to occupants in the kitchen. Particle number and mass concentrations remained elevated for 90 min in the kitchen and for 60 min in the living room after cooking. Particles in cooking emissions were mainly in the ultrafine size range in terms of the number count while AMPs contributed to at least 60% of the surface area concentrations in the kitchen and 73% in the living room. This suggests that AMPs could still be a major health concern since the particle surface area concentration is suggested to have a more direct relationship with inhalation toxicity than with number concentration. Particle number concentration (14.6-661.2 nm) in the living room was about 2.7 times that in the outdoor environment, suggesting that better ventilation could help reduce exposure.

Aerosol characteristics in the entrainment interface layer in relation to the marine boundary layer and free troposphere

NASA Astrophysics Data System (ADS)

Dadashazar, Hossein; Braun, Rachel A.; Crosbie, Ewan; Chuang, Patrick Y.; Woods, Roy K.; Jonsson, Haflidi H.; Sorooshian, Armin

2018-02-01

This study uses airborne data from two field campaigns off the California coast to characterize aerosol size distribution characteristics in the entrainment interface layer (EIL), a thin and turbulent layer above marine stratocumulus cloud tops, which separates the stratocumulus-topped boundary layer (STBL) from the free troposphere (FT). The vertical bounds of the EIL are defined in this work based on considerations of buoyancy and turbulence using thermodynamic and dynamic data. Aerosol number concentrations are examined from three different probes with varying particle diameter (Dp) ranges: > 3 nm, > 10 nm, and 0.11-3.4 µm. Relative to the EIL and FT layers, the sub-cloud (SUB) layer exhibited lower aerosol number concentrations and higher surface area concentrations. High particle number concentrations between 3 and 10 nm in the EIL are indicative of enhanced nucleation, assisted by high actinic fluxes, cool and moist air, and much lower surface area concentrations than the STBL. Slopes of number concentration versus altitude in the EIL were correlated with the particle number concentration difference between the SUB and lower FT layers. The EIL aerosol size distribution was influenced by varying degrees from STBL aerosol versus subsiding FT aerosol depending on the case examined. These results emphasize the important role of the EIL in influencing nucleation and aerosol-cloud-climate interactions.

Sublethal concentrations of silver nanoparticles affect the mechanical stability of biofilms.

PubMed

Grün, Alexandra Y; Meier, Jutta; Metreveli, George; Schaumann, Gabriele E; Manz, Werner

2016-12-01

Bacterial biofilms are most likely confronted with silver nanoparticles (Ag NPs) as a pollutant stressor in aquatic systems. In this study, biofilms of Aquabacterium citratiphilum were exposed for 20 h to 30 and 70 nm citrate stabilized Ag NPs in low-dose concentrations ranging from 600 to 2400 μg l -1 , and the Ag NP-mediated effects on descriptive, structural, and functional biofilm characteristics, including viability, protein content, architecture, and mechanical stability, were investigated. Viability, based on the bacterial cell membrane integrity of A. citratiphilum, as determined by epifluorescence microscopy, remained unaffected after Ag NP exposure. Moreover, in contrast to information in the current literature, protein contents of cells and extracellular polymeric substances (EPS) and biofilm architecture, including dry mass, thickness, and density, were not significantly impacted by exposure to Ag NPs. However, the biofilms themselves served as effective sinks for Ag NPs, exhibiting enrichment factors from 5 to 8. Biofilms showed a greater capacity to accumulate 30 nm sized Ag NPs than 70 nm Ag NPs. Furthermore, Ag NPs significantly threatened the mechanical stability of biofilms, as determined by a newly developed assay. For 30 nm Ag NPs, the mechanical stability of biofilms decreased as the Ag NP concentrations applied to them increased. In contrast, 70 nm Ag NPs produced a similar decrease in mechanical stability for each applied concentration. Overall, this finding demonstrates that exposure to Ag NPs triggers remarkable changes in biofilm adhesion and/or cohesiveness. Because of biofilm-mediated ecological services, this response raises environmental concerns regarding Ag NP release into freshwater systems, even in sublethal concentrations.

Synthesis and Luminescence Properties of Blue Na(Sr0.97-xCa(x))PO4:0.03Eu2+ Phosphors for White Light Emitting Diode Applications.

PubMed

Hakeem, D A; Park, K

2015-07-01

The crystal structure and luminescence properties of Na(Sr0.97-xCax)PO4:0.03Eu2+ (0 < x < 1.0) phosphors were studied, depending on the Ca2+ concentration. All the Na(Sr0.97-xCax)PO4:0.03Eu2+ phosphors had a hexagonal crystal structure. The excitation spectra of the prepared phosphors showed a broad band ranging from 250 to 420 nm, which arises due to the 4f-5d transitions of Eu2+ ions. Upon the excitation of 334 nm wavelength, the emission spectra showed a broad blue band ranging from 400 to 700 nm peaking at 450 nm. Among the prepared phosphors, the Na(Sr0.72Ca0.25)PO4:0.03Eu2+ showed the strongest emission intensity and could be applied as a blue emitting phosphor for UV-based w-LEDs.

Design of an ultraviolet fluorescence lidar for biological aerosol detection

NASA Astrophysics Data System (ADS)

Rao, Zhimin; Hua, Dengxin; He, Tingyao; Le, Jing

2016-09-01

In order to investigate the biological aerosols in the atmosphere, we have designed an ultraviolet laser induced fluorescence lidar based on the lidar measuring principle. The fluorescence lidar employs a Nd:YAG laser of 266 nm as an excited transmitter, and examines the intensity of the received light at 400 nm for biological aerosol concentration measurements. In this work, we firstly describe the designed configuration and the simulation to estimate the measure range and the system resolution of biological aerosol concentration under certain background radiation. With a relative error of less than 10%, numerical simulations show the system is able to monitor biological aerosols within detected distances of 1.8 km and of 7.3 km in the daytime and nighttime, respectively. Simulated results demonstrate the designed fluorescence lidar is capable to identify a minimum concentration of biological aerosols at 5.0×10-5 ppb in the daytime and 1.0×10-7 ppb in the nighttime at the range of 0.1 km. We believe the ultraviolet laser induced fluorescence lidar can be spread in the field of remote sensing of biological aerosols in the atmosphere.

Wavelength dependence of Verdet constant of Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics

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

Snetkov, I. L., E-mail: snetkov@appl.sci-nnov.ru; Palashov, O. V.; Permin, D. A.

2016-04-18

Samples of the magneto-active material—Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics with Tb{sup 3+} ion concentrations of 10%, 20%, 30%, and 100% (Tb{sub 2}O{sub 3})—were prepared and studied. The wavelength dependence of Verdet constant in the 380 nm–1750 nm range was approximated for all investigated ceramic samples and was predicted for a pure Tb{sub 2}O{sub 3} material. Tb{sub 2}O{sub 3} ceramics demonstrates a more than three times higher Verdet constant in comparison with terbium gallium garnet crystal or ceramics. The linear dependence of the Verdet constant on Tb{sup 3+} ion concentration in the Tb{sup 3+}:Y{sub 2}O{sub 3} ceramics was demonstrated. The obtained data willmore » be useful for fabricating magneto-optical elements of Faraday devices based on Tb{sup 3+}:Y{sub 2}O{sub 3} with arbitrary Tb{sup 3+} ion concentration operating at room temperature in the wavelength range of 380 nm–1750 nm.« less

Measurement of refractive index of hemoglobin in the visible/NIR spectral range.

PubMed

Lazareva, Ekaterina N; Tuchin, Valery V

2018-03-01

This study is focused on the measurements of the refractive index of hemoglobin solutions in the visible/near-infrared (NIR) spectral range at room temperature for characteristic laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 930, 1100, 1300, and 1550 nm. Measurements were performed using the multiwavelength Abbe refractometer. Aqua hemoglobin solutions of different concentrations obtained from human whole blood were investigated. The specific increment of refractive index on hemoglobin concentration and the Sellmeier coefficients were calculated. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Near-infrared spectroscopy of renal tissue in vivo

NASA Astrophysics Data System (ADS)

Grosenick, Dirk; Steinkellner, Oliver; Wabnitz, Heidrun; Macdonald, Rainer; Niendorf, Thoralf; Cantow, Kathleen; Flemming, Bert; Seeliger, Erdmann

2013-03-01

We have developed a method to quantify hemoglobin concentration and oxygen saturation within the renal cortex by near-infrared spectroscopy. A fiber optic probe was used to transmit the radiation of three semiconductor lasers at 690 nm, 800 nm and 830 nm to the tissue, and to collect diffusely remitted light at source-detector separations from 1 mm to 4 mm. To derive tissue hemoglobin concentration and oxygen saturation of hemoglobin the spatial dependence of the measured cw intensities was fitted by a Monte Carlo model. In this model the tissue was assumed to be homogeneous. The scaling factors between measured intensities and simulated photon flux were obtained by applying the same setup to a homogeneous semi-infinite phantom with known optical properties and by performing Monte Carlo simulations for this phantom. To accelerate the fit of the tissue optical properties a look-up table of the simulated reflected intensities was generated for the needed range of absorption and scattering coefficients. The intensities at the three wavelengths were fitted simultaneously using hemoglobin concentration, oxygen saturation, the reduced scattering coefficient at 800 nm and the scatter power coefficient as fit parameters. The method was employed to study the temporal changes of renal hemoglobin concentration and blood oxygenation on an anesthetized rat during a short period of renal ischemia induced by aortic occlusion and during subsequent reperfusion.

Synthesis and luminescence properties of blue-emitting phosphor Ca12 Al14 O32 F2 :Eu2+ for white light-emitting diode.

PubMed

Chen, Wanping; Zhang, Xinzhu; Wang, Liping

2017-09-01

A blue-emitting phosphor Ca 12 Al 14 O 32 F 2 :Eu 2+ was synthesized using a high-temperature solid-state reaction under a reductive atmosphere. The X-ray diffraction measurements indicate that a pure phase Ca 12 Al 14 O 32 F 2 :Eu 2+ can be obtained for low doping concentration of Eu 2+ . The phosphor has a strong absorption in the range 270-420 nm with a maximum at ~340 nm and blue emission in the range 400-500 nm with chromatic coordination of (0.152, 0.045). The optimal doping concentration is ~0.24. In addition, the luminescence properties of the as-synthesized phosphor were evaluated by comparison with those of Ca 12 Al 14 O 32 Cl 2 :Eu 2+ and the commercially available phosphor BaMgAl 10 O 17 :Eu 2+ . The emission intensity of Ca 12 Al 14 O 32 F 2 :Eu 2+ was ~72% that of BaMgAl 10 O 17 :Eu 2+ under excitation at λ = 375 nm. The results indicate that Ca 12 Al 14 O 32 F 2 :Eu 2+ has potential application as a near-UV-convertible blue phosphor for white light-emitting diodes. Copyright © 2017 John Wiley & Sons, Ltd.

Evaluation of cytotoxicity and radiation enhancement using 1.9 nm gold particles: potential application for cancer therapy

PubMed Central

Butterworth, K T; Coulter, J A; Jain, S; Forker, J; McMahon, S J; Schettino, G; Prise, K M; Currell, F J; Hirst, D G

2010-01-01

High atomic number (Z) materials such as gold preferentially absorb kilovoltage x-rays compared to soft tissue and may be used to achieve local dose enhancement in tumours during treatment with ionizing radiation. Gold nanoparticles have been demonstrated as radiation dose enhancing agents in vivo and in vitro. In the present study, we used multiple endpoints to characterize the cellular cytotoxic response of a range of cell lines to 1.9 nm gold particles and measured dose modifying effects following transient exposure at low concentrations. Gold nanoparticles caused significant levels of cell type specific cytotoxicity, apoptosis and increased oxidative stress. When used as dose modifying agents, dose enhancement factors varied between the cell lines investigated with the highest enhancement being 1.9 in AGO-1522B cells at a nanoparticle concentration of 100 μg ml−1. This study shows exposure to 1.9 nm gold particles to induce a range of cell line specific responses including decreased clonogenic survival, increased apoptosis and induction of DNA damage which may be mediated through the production of reactive oxygen species. This is the first study involving 1.9 nm nanometre sized particles to report multiple cellular responses which impact on the radiation dose modifying effect. The findings highlight the need for extensive characterization of responses to gold nanoparticles when assessing dose enhancing potential in cancer therapy. PMID:20601762

Determination of permeability of ultra-fine cupric oxide aerosol through military filters and protective filters

NASA Astrophysics Data System (ADS)

Kellnerová, E.; Večeřa, Z.; Kellner, J.; Zeman, T.; Navrátil, J.

2018-03-01

The paper evaluates the filtration and sorption efficiency of selected types of military combined filters and protective filters. The testing was carried out with the use of ultra-fine aerosol containing cupric oxide nanoparticles ranging in size from 7.6 nm to 299.6 nm. The measurements of nanoparticles were carried out using a scanning mobility particle sizer before and after the passage through the filter and a developed sampling device at the level of particle number concentration approximately 750000 particles·cm-3. The basic parameters of permeability of ultra-fine aerosol passing through the tested material were evaluated, in particular particle size, efficiency of nanoparticle capture by filter, permeability coefficient and overall filtration efficiency. Results indicate that the military filter and particle filters exhibited the highest aerosol permeability especially in the nanoparticle size range between 100–200 nm, while the MOF filters had the highest permeability in the range of 200 to 300 nm. The Filter Nuclear and the Health and Safety filter had 100% nanoparticle capture efficiency and were therefore the most effective. The obtained measurement results have shown that the filtration efficiency over the entire measured range of nanoparticles was sufficient; however, it was different for particular particle sizes.

Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

1996-01-01

The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

Photoinduced nucleation: a novel tool for detecting molecules in air at ultra-low concentrations

DOEpatents

Katz, Joseph L.; Lihavainen, Heikki; Rudek, Markus M.; Salter, Brian C.

2002-01-01

A method and apparatus for determining the presence of molecules in a gas at concentrations of less than about 100 ppb. Light having wavelengths in the range from about 200 nm to about 350 nm is used to illuminate a flowing sample of the gas causing the molecules if present to form clusters. A mixture of the illuminated gas and a vapor is cooled until the vapor is supersaturated so that there is a small rate of homogeneous nucleation. The supersaturated vapor condenses on the clusters thus causing the clusters to grow to a size sufficient to be counted by light scattering and then the clusters are counted.

Adsorption and Depletion Regimes of a Nonionic Surfactant in Hydrophilic Mesopores: An Experimental and Simulation Study

DOE PAGES

Müter, Dirk; Rother, Gernot; Bock, Henry; ...

2017-08-15

Adsorption and aggregation of nonionic surfactants at oxide surfaces has been studied extensively in the past, but only for concentrations below and near the critical micelle concentration. In this paper, we report an adsorption study of a short-chain surfactant (C 6E 3) in porous silica glass of different pore sizes (7.5 to 50 nm), covering a wide composition range up to 50 wt % in a temperature range from 20 °C to the LCST. Aggregative adsorption is observed at low concentrations, but the excess concentration of C 6E 3 in the pores decreases and approaches zero at higher bulk concentrations.more » Strong depletion of surfactant (corresponding to enrichment of water in the pores) is observed in materials with wide pores at high bulk concentrations. We propose an explanation for the observed pore-size dependence of the azeotropic point. Mesoscale simulations based on dissipative particle dynamics (DPD) were performed to reveal the structural origin of this transition from the adsorption to the depletion regime. The simulated adsorption isotherms reproduce the behavior found in the 7.5 nm pores. Finally, the calculated bead density profiles indicate that the repulsive interaction of surfactant head groups causes a depletion of surfactant in the region around the corona of the surface micelles.« less

Cytotoxicity and cellular uptake of different sized gold nanoparticles in ovarian cancer cells

NASA Astrophysics Data System (ADS)

Kumar, Dhiraj; Mutreja, Isha; Chitcholtan, Kenny; Sykes, Peter

2017-11-01

Nanomedicine has advanced the biomedical field with the availability of multifunctional nanoparticles (NPs) systems that can target a disease site enabling drug delivery and helping to monitor the disease. In this paper, we synthesised the gold nanoparticles (AuNPs) with an average size 18, 40, 60 and 80 nm, and studied the effect of nanoparticles size, concentration and incubation time on ovarian cancer cells namely, OVCAR5, OVCAR8, and SKOV3. The size measured by transmission electron microscopy images was slightly smaller than the hydrodynamic diameter; measured size by ImageJ as 14.55, 38.13, 56.88 and 78.56 nm. The cellular uptake was significantly controlled by the AuNPs size, concentration, and the cell type. The nanoparticles uptake increased with increasing concentration, and 18 and 80 nm AuNPs showed higher uptake ranging from 1.3 to 5.4 μg depending upon the concentration and cell type. The AuNPs were associated with a temporary reduction in metabolic activity, but metabolic activity remained more than 60% for all sample types; NPs significantly affected the cell proliferation activity in first 12 h. The increase in nanoparticle size and concentration induced the production of reactive oxygen species in 24 h.

Oxidative stress studies of six Ti02 and two Ce02 nanomaterials: Immune-spin trapping results with DNA

EPA Science Inventory

Six Ti02 and two Ce02 nanomaterials with dry sizes ranging from 6 to 410 nm were tested for their ability to cause DNA centered free radicals in vitro in the concentration range of 10 to 3,000 ug/ml. All eight of the nanomaterials significantly increased the adduction of the spin...

Relationships of outdoor and indoor ultrafine particles at residences downwind of a major international border crossing in Buffalo, NY.

PubMed

McAuley, T R; Fisher, R; Zhou, X; Jaques, P A; Ferro, A R

2010-08-01

During winter 2006, indoor and outdoor ultrafine particle (UFP) size distribution measurements for particles with diameters from 5.6 to 165 nm were taken at five homes in a neighborhood directly adjacent to the Peace Bridge Complex (PBC), a major international border crossing connecting Buffalo, New York to Fort Erie, Ontario. Monitoring with 1-s time resolution was conducted for several hours at each home. Participants were instructed to keep all external windows and doors closed and to refrain from cooking, smoking, or other activity that may result in elevating the indoor UFP number concentration. Although the construction and age for the homes were similar, indoor-to-outdoor comparisons indicate that particle infiltration rates varied substantially. Overall, particle concentrations indoors were lower and less variable than particle concentrations outdoors, with average indoor-outdoor ratios ranging from 0.1 to 0.5 (mean 0.34) for particles between 5.6 and 165 nm in diameter. With no indoor sources, the average indoor-outdoor ratios were lowest (0.2) for 20-nm particles, higher (0.3) for particles <10 nm, and highest (0.5) for particles 70-165 nm. This study provides insight into the penetration of UFP into homes and the resulting change in particle size distributions as particles move indoors near a major diesel traffic source. Although people spend most of their time in their homes, exposure estimates for epidemiological studies are generally determined using ambient concentrations. The findings of this study will contribute to improved size-resolved UFP exposure estimates for near roadway exposure assessments and epidemiological studies.

Quantitative estimation of itopride hydrochloride and rabeprazole sodium from capsule formulation.

PubMed

Pillai, S; Singhvi, I

2008-09-01

Two simple, accurate, economical and reproducible UV spectrophotometric methods and one HPLC method for simultaneous estimation of two component drug mixture of itopride hydrochloride and rabeprazole sodium from combined capsule dosage form have been developed. First developed method involves formation and solving of simultaneous equations using 265.2 nm and 290.8 nm as two wavelengths. Second method is based on two wavelength calculation, wavelengths selected for estimation of itopride hydrochloride was 278.0 nm and 298.8 nm and for rabeprazole sodium 253.6 nm and 275.2 nm. Developed HPLC method is a reverse phase chromatographic method using phenomenex C(18) column and acetonitrile: phosphate buffer (35:65 v/v) pH 7.0 as mobile phase. All developed methods obey Beer's law in concentration range employed for respective methods. Results of analysis were validated statistically and by recovery studies.

Quantitative Estimation of Itopride Hydrochloride and Rabeprazole Sodium from Capsule Formulation

PubMed Central

Pillai, S.; Singhvi, I.

2008-01-01

Two simple, accurate, economical and reproducible UV spectrophotometric methods and one HPLC method for simultaneous estimation of two component drug mixture of itopride hydrochloride and rabeprazole sodium from combined capsule dosage form have been developed. First developed method involves formation and solving of simultaneous equations using 265.2 nm and 290.8 nm as two wavelengths. Second method is based on two wavelength calculation, wavelengths selected for estimation of itopride hydrochloride was 278.0 nm and 298.8 nm and for rabeprazole sodium 253.6 nm and 275.2 nm. Developed HPLC method is a reverse phase chromatographic method using phenomenex C18 column and acetonitrile: phosphate buffer (35:65 v/v) pH 7.0 as mobile phase. All developed methods obey Beer's law in concentration range employed for respective methods. Results of analysis were validated statistically and by recovery studies. PMID:21394269

SEM and AFM studies of dip-coated CuO nanofilms.

PubMed

Dhanasekaran, V; Mahalingam, T; Ganesan, V

2013-01-01

Cupric oxide (CuO) semiconducting thin films were prepared at various copper sulfate concentrations by dip coating. The copper sulfate concentration was varied to yield films of thicknesses in the range of 445-685 nm by surface profilometer. X-ray diffraction patterns revealed that the deposited films were polycrystalline in nature with monoclinic structure of (-111) plane. The surface morphology and topography of monoclinic-phase CuO thin films were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. Surface roughness profile was plotted using WSxM software and the estimated surface roughness was about ∼19.4 nm at 30 mM molar concentration. The nanosheets shaped grains were observed by SEM and AFM studies. The stoichiometric compound formation was observed at 30 mM copper sulfate concentration prepared film by EDX. The indirect band gap energy of CuO films was increased from 1.08 to 1.20 eV with the increase of copper sulfate concentrations. Copyright © 2012 Wiley Periodicals, Inc.

Effect of capping agent on selectivity and sensitivity of CdTe quantum dots optical sensor for detection of mercury ions

NASA Astrophysics Data System (ADS)

Labeb, Mohmed; Sakr, Abdel-Hamed; Soliman, Moataz; Abdel-Fettah, Tarek M.; Ebrahim, Shaker

2018-05-01

Cadmium telluride (CdTe) quantum dots (QDs) were prepared from an aqueous solution containing CdCl2 and Te precursor in the presence of thioglycolic acid (TGA) or L-cysteine as capping agents. Two optical sensors have been developed for Hg2+ ions with very low concentration in the range of nanomolar (nM) or picomolar (pM) depending on the type of capping agents and based on photoluminescence (PL) quenching of CdTe QDs. It was observed that low concentrations of Hg2+ ions quench the fluorescence spectra of CdTe QDs and TGA capped CdTe QDs exhibited a linear response to Hg2+ ions in the concentration range from 1.25 to 10 nM. Moreover, it was found that L-cysteine capped CdTe QDs optical sensor with a sensitivity of 6 × 109 M-1, exhibited a linear coefficient of 0.99 and showed a detection limit of 2.7 pM in range from 5 to 25 pM of Hg2+ ions was achieved. In contrast to the significant response that was observed for Hg2+, a weak signal response was noted upon the addition of other metal ions indicating an excellent selectivity of CdTe QDs towards Hg2+.

Physicochemical properties of aerosol released in the case of a fire involving materials used in the nuclear industry.

PubMed

Ouf, F-X; Mocho, V-M; Pontreau, S; Wang, Z; Ferry, D; Yon, J

2015-01-01

For industrial concerns, and more especially for nuclear applications, the characterization of soot is essential for predicting the behaviour of containment barriers in fire conditions. This study deals with the characterization (emission factor, composition, size, morphology, microstructure) of particles produced during thermal degradation of materials found in nuclear facilities (electrical cables, polymers, oil and solvents). Small-scale experiments have been conducted for oxygen concentrations [O2] ranging from 15% to 21% in order to imitate the oxygen depletion encountered during a confined fire. Particles denote distinct shapes, from aggregates composed of monomers with diameters ranging from 31.2 nm to 52.8 nm, to compact nanoparticles with diameters ranging from 15 nm to 400 nm, and their composition strongly depends on fuel type. Despite the organic to total carbon ratio (OC/TC), their properties are poorly influenced by the decrease in [O2]. Finally, two empirical correlations are proposed for predicting the OC/TC ratio and the monomer diameter, respectively, as a function of the fuel's carbon to hydrogen ratio and the emission factor. Copyright © 2014 Elsevier B.V. All rights reserved.

Sensitivity in forward modeled hyperspectral reflectance due to phytoplankton groups

NASA Astrophysics Data System (ADS)

Manzo, Ciro; Bassani, Cristiana; Pinardi, Monica; Giardino, Claudia; Bresciani, Mariano

2016-04-01

Phytoplankton is an integral part of the ecosystem, affecting trophic dynamics, nutrient cycling, habitat condition, and fisheries resources. The types of phytoplankton and their concentrations are used to describe the status of water and the processes inside of this. This study investigates bio-optical modeling of phytoplankton functional types (PFT) in terms of pigment composition demonstrating the capability of remote sensing to recognize freshwater phytoplankton. In particular, a sensitivity analysis of simulated hyperspectral water reflectance (with band setting of HICO, APEX, EnMAP, PRISMA and Sentinel-3) of productive eutrophic waters of Mantua lakes (Italy) environment is presented. The bio-optical model adopted for simulating the hyperspectral water reflectance takes into account the reflectance dependency on geometric conditions of light field, on inherent optical properties (backscattering and absorption coefficients) and on concentrations of water quality parameters (WQPs). The model works in the 400-750nm wavelength range, while the model parametrization is based on a comprehensive dataset of WQP concentrations and specific inherent optical properties of the study area, collected in field surveys carried out from May to September of 2011 and 2014. The following phytoplankton groups, with their specific absorption coefficients, a*Φi(λ), were used during the simulation: Chlorophyta, Cyanobacteria with phycocyanin, Cyanobacteria and Cryptophytes with phycoerythrin, Diatoms with carotenoids and mixed phytoplankton. The phytoplankton absorption coefficient aΦ(λ) is modelled by multiplying the weighted sum of the PFTs, Σpia*Φi(λ), with the chlorophyll-a concentration (Chl-a). To highlight the variability of water reflectance due to variation of phytoplankton pigments, the sensitivity analysis was performed by keeping constant the WQPs (i.e., Chl-a=80mg/l, total suspended matter=12.58g/l and yellow substances=0.27m-1). The sensitivity analysis was based on the decomposition of the output reflectance variance in partial variances of the output due to each functional group. This approach considers the sensitivity analysis of the model to each variable on its own and the corresponding interaction with the other variables, allowing identifying the single variability as well as the spectral interaction index. The analysis recognized three spectral ranges with specific level of interactions between the inputs. The first part of the spectrum up to 500 nm had average level of 10% of interaction; the second up to 600nm showed values of 5% with a peak around 580nm; the third showed an increasing interaction level until 15% near 715nm. The results presented in this study provide information relating the sensitivity of hyperspectral water reflectance as observable with band setting of the latest generation space- and air-borne sensors depending on different phytoplankton groups. In particular PRISMA was the best in the spectral sensitivity definition in the first part of the spectrum, while APEX in the second and third domain. The Sentinel 3 showed lower performances although in the third domain it was able to identify some spectral features. Results showed the Chlorophyta had high main effect at 440 nm and 480nm; sensitivity indices of phycoerythrin showed peaks at 550-580nm the range and near 680nm; phycocyanin showed high influence at 620-640nm. The research activity is part of the EU FP7 INFORM (Grant No. 606865, http://www.copernicus-inform.eu/).

The refractive index of human hemoglobin in the visible range.

PubMed

Zhernovaya, O; Sydoruk, O; Tuchin, V; Douplik, A

2011-07-07

Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l(-1). This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l(-1). The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

Effect of concentration variation on 2.0 µm emission of Ho3+-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 oxyfluorosilicate glasses

NASA Astrophysics Data System (ADS)

Gelija, Devarajulu; Borelli, Deva Prasad Raju

2018-02-01

The concentration variation of Ho3+ ion-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses has been prepared by conventional melt quenching method. The thermal stability of 1 mol % of Ho3+-doped oxyfluorosilicate glass has been calculated using the differential thermal analysis (DTA) spectra. The phenomenological Judd-Ofelt intensity parameters Ωλ ( λ = 2, 4 and 6) were calculated for all concentrations of Ho3+ ions. The luminescence spectra in visible region of Ho3+ ion-doped glasses were recorded under the excitation wavelength of 452 nm. The spectra consists of several intense emission bands (5F4, 5S2) → 5I8 (547 nm), 5F3 → 5I8 (647 nm), 5F5 → 5I7 (660 nm) and (5F4, 5S2) → 5I7 (750 nm) in the range 500-780 nm. The fluorescence emission at ˜2.0 µm (5I7 → 5I8) was observed under the excitation of 488 nm Ar-ion laser. The stimulated emission cross section for 5I7 → 5I8 transition (˜2.0 µm) varies from 8.46 to 9.52 × 10-21 cm2, as calculated by the Fuchtbauer-Ladenburg (FL) theory. However, Mc-Cumber theory was used to calculate emission cross section values about 4.24-5.75 × 10-21 cm2 for the 5I7 → 5I8 transition in all concentrations of Ho3+-doped oxyfluorosilicate glasses. Therefore, these results reveal that the 0.5 mol % of Ho3+-doped oxyfluorosilicate glasses, exhibiting higher emission cross section, has potentially been used for laser applications at ˜ 2.0 µm.

Spectrometric Estimation of Total Nitrogen Concentration in Douglas-Fir Foliage

NASA Technical Reports Server (NTRS)

Johnson, Lee F.; Billow, Christine R.; Peterson, David L. (Technical Monitor)

1995-01-01

Spectral measurements of fresh and dehydrated Douglas-fir foliage, from trees cultivated under three fertilization treatments, were acquired with a laboratory spectrophotometer. The slope (first-derivative) of the fresh- and dry-leaf absorbance spectra at locations near known protein absorption features was strongly correlated with total nitrogen (TN) concentration of the foliage samples. Particularly strong correlation was observed between the first-derivative spectra in the 2150-2170 nm region and TN, reaching a local maximum in the fresh-leaf spectra of -0.84 at 2 160 nm. Stepwise regression was used to generate calibration equations relating first derivative spectra from fresh, dry/intact, and dry/ground samples to TN concentration. Standard errors of calibration were 1.52 mg g-1 (fresh), 1.33 (dry/intact), and 1.20 (dry/ground), with goodness-of-fit 0.94 and greater. Cross-validation was performed with the fresh-leaf dataset to examine the predictive capability of the regression method; standard errors of prediction ranged from 1.47 - 2.37 mg g(exp -1) across seven different validation sets, prediction goodness of fit ranged from .85-.94, and wavelength selection was fairly insensitive to the membership of the calibration set. All regressions in this study tended to select wavelengths in the 2100-2350 nm region, with the primary selection in the 2142-2172 nm region. The study provides positive evidence concerning the feasibility of assessing TN status of fresh-leaf samples by spectrometric means. We assert that the ability to extract biochemical information from fresh-leaf spectra is a necessary but insufficient condition regarding the use of remote sensing for canopy-level biochemical estimation.

Development of a NanoBioAnalytical platform for "on-chip" qualification and quantification of platelet-derived microparticles.

PubMed

Obeid, Sameh; Ceroi, Adam; Mourey, Guillaume; Saas, Philippe; Elie-Caille, Celine; Boireau, Wilfrid

2017-07-15

Blood microparticles (MPs) are small membrane vesicles (50-1000nm), derived from different cell types. They are known to play important roles in various biological processes and also recognized as potential biomarkers of various health disorders. Different methods are currently used for the detection and characterization of MPs, but none of these methods is capable to quantify and qualify total MPs at the same time, hence, there is a need to develop a new approach for simultaneous detection, characterization and quantification of microparticles. Here we show the potential of surface plasmon resonance (SPR) method coupled to atomic force microscopy (AFM) to quantify and qualify platelet-derived microparticles (PMPs), on the whole nano-to micro-meter scale. The different subpopulations of microparticles could be determined via their capture onto the surface using specific ligands. In order to verify the correlation between the capture level and the microparticles concentration in solution, two calibration standards were used: Virus-Like Particles (VLPs) and synthetic beads with a mean diameter of 53nm and 920nm respectively. The AFM analysis of the biochip surface allowed metrological analysis of captured PMPs and revealed that more than 95% of PMPs were smaller than 300nm. Our results suggest that our NanoBioAnalytical platform, combining SPR and AFM, is a suitable method for a sensitive, reproducible, label-free characterization and quantification of MPs over a wide concentration range (≈10 7 to 10 12 particles/mL; with a limit of detection (LOD) in the lowest ng/µL range) which matches with their typical concentrations in blood. Copyright © 2016 Elsevier B.V. All rights reserved.

Barium Nitrate Raman Laser Development for Remote Sensing of Ozone

NASA Technical Reports Server (NTRS)

McCray, Christopher L.; Chyba, Thomas H.

1997-01-01

In order to understand the impact of anthropogenic emissions upon the earth's environment, scientists require remote sensing techniques which are capable of providing range-resolved measurements of clouds, aerosols, and the concentrations of several chemical constituents of the atmosphere. The differential absorption lidar (DIAL) technique is a very promising method to measure concentration profiles of chemical species such as ozone and water vapor as well as detect the presence of aerosols and clouds. If a suitable DIAL system could be deployed in space, it would provide a global data set of tremendous value. Such systems, however, need to be compact, reliable, and very efficient. In order to measure atmospheric gases with the DIAL technique, the laser transmitter must generate suitable on-line and off-line wavelength pulse pairs. The on-line pulse is resonant with an absorption feature of the species of interest. The off-line pulse is tuned so that it encounters significantly less absorption. The relative backscattered power for the two pulses enables the range-resolved concentration to be computed. Preliminary experiments at NASA LaRC suggested that the solid state Raman shifting material, Ba(NO3)2, could be utilized to produce these pulse pairs. A Raman oscillator pumped at 532 nm by a frequency-doubled Nd:YAG laser can create first Stokes laser output at 563 nm and second Stokes output at 599 nm. With frequency doublers, UV output at 281 nm and 299 nm can be subsequently obtained. This all-solid state system has the potential to be very efficient, compact, and reliable. Raman shifting in Ba(NO3)2, has previously been performed in both the visible and the infrared. The first Raman oscillator in the visible region was investigated in 1986 with the configurations of plane-plane and unstable telescopic resonators. However, most of the recent research has focused on the development of infrared sources for eye-safe lidar applications.

Application of normal fluorescence and stability-indicating derivative synchronous fluorescence spectroscopy for the determination of gliquidone in presence of its fluorescent alkaline degradation product

NASA Astrophysics Data System (ADS)

El-ghobashy, Mohamed R.; Yehia, Ali M.; Helmy, Aya H.; Youssef, Nadia F.

2018-01-01

Simple, smart and sensitive normal fluorescence and stability-indicating derivative synchronous spectrofluorimetric methods have been developed and validated for the determination of gliquidone in the drug substance and drug product. Normal spectrofluorimetric method of gliquidone was established in methanol at λ excitation 225 nm and λ emission 400 nm in concentration range 0.2-3 μg/ml with LOD equal 0.028. The fluorescence quantum yield of gliquidone was calculated using quinine sulfate as a reference and found to be 0.542. Stability-indicating first and third derivative synchronous fluorescence spectroscopy were successfully utilized to overcome the overlapped spectra in normal fluorescence of gliquidone and its alkaline degradation product. Derivative synchronous methods are based on using the synchronous fluorescence of gliquidone and its degradation product in methanol at Δ λ50 nm. Peak amplitude in the first derivative of synchronous fluorescence spectra was measured at 309 nm where degradation product showed zero-crossing without interference. The peak amplitudes in the third derivative of synchronous fluorescence spectra, peak to trough were measured at 316,329 nm where degradation product showed zero-crossing. The different experimental parameters affecting the normal and synchronous fluorescence intensity of gliquidone were studied and optimized. Moreover, the cited methods have been validated as per ICH guidelines. The peak amplitude-concentration plots of the derivative synchronous fluorescence were linear over the concentration range 0.05-2 μg/ml for gliquidone. Limits of detection were 0.020 and 0.022 in first and third derivative synchronous spectra, respectively. The adopted methods were successfully applied to commercial tablets and the results demonstrated that the derivative synchronous fluorescence spectroscopy is a powerful stability-indicating method, suitable for routine use with a short analysis time. Statistical comparison between the results obtained by normal fluorescence and derivative synchronous methods and the official one using student's t-test and F-ratio showed no significant difference regarding accuracy and precision.

Tuning from green to red the upconversion emission of Y2O3:Er3+-Yb3+ nanophosphors

NASA Astrophysics Data System (ADS)

Diaz-Torres, L. A.; Salas, P.; Oliva, J.; Resendiz-L, E.; Rodriguez-Gonzalez, C.; Meza, O.

2017-01-01

In this work, the structural, morphological and luminescent properties of Y2O3 nanophosphors doped with Er3+ (1 mol%) and different Yb3+ concentrations (2-12 mol%) have been studied. Those nanophosphors were synthesized using a simple hydrothermal method. XRD analysis indicates that all the samples presented a pure cubic phase even for Yb concentrations as high as 12 mol%. In addition, SEM images show nanoparticles with quasi-spherical shapes with average sizes in the range of 300-340 nm. Photoluminescence measurements obtained after excitation at 967 nm revealed that our samples have strong green (563 nm) and red emissions (660 nm) corresponding to 2H11/2 + 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ ions, respectively. We also observed that the green band is quenched and the red emission enhanced as the Yb concentration increases. In consequence, the CIE coordinates changed from (0.35, 0.64) in the green region to (0.59, 0.39) in the red region. Thus, the tuning properties of Y2O3 nanophosphors suggest that they are good candidates for applications in lighting.

Noninvasive investigation of skin local hypothermia influence upon local oxygenation and hemoglobin concentration

NASA Astrophysics Data System (ADS)

Douplik, Alexandre Y.; Kessler, Manfred D.; Kakihana, Yasuyuki; Krug, Alfons

1997-08-01

Functional evaluation of local hemoglobin concentration and hemoglobin oxygenation based on back scattering spectra from human skin in vivo have been obtained in visible range (502 - 628 nm) by a rapid microlightguide spectrometer (EMPHO II) with step 250 micrometer. Analysis of received results has shown that during local cooling there is two nearly simultaneous reactions: reduction of hemoglobin concentration and increase of hemoglobin oxygenation level. In a case when one has used previous heating of planning place for cooling, reduction of hemoglobin concentration is expressed higher by 22 - 33%.

Characteristic of nanoparticles generated from different nano-powders by using different dispersion methods

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Lin, Guan-Yu; Liu, Chun-Nan; He, Chi-En; Chen, Chun-Wan

2012-03-01

A standard rotating drum with a modified sampling train (RD), a vortex shaker (VS), and a SSPD (small-scale powder disperser) were used to investigate the emission characteristics of nano-powders, including nano-titanium dioxide (nano-TiO2, primary diameter: 21 nm), nano-zinc oxide (nano-ZnO, primary diameter: 30-50 nm), and nano-silicon dioxide (nano-SiO2, primary diameter: 10-30 nm). A TSI SMPS (scanning mobility particle sizer), a TSI APS (aerodynamic particle sizer), and a MSP MOUDI (micro-orifice uniform deposit impactor) were used to measure the number and mass distributions of generated particles. Significant differences in specific number and mass concentration or distributions were found among different methods and nano-powders with the most specific number and mass concentration and the smallest particles being generated by the most energetic SSPD, followed by VS and RD. Near uni-modal number or mass distributions were observed for the SSPD while bi-modal number or mass distributions existed for nano-powders except nano-SiO2 which also exhibited bimodal mass distributions. The 30-min average results showed that the mass median aerodynamic diameter (MMAD) and number median diameter (NMD) of the SSPD ranged 1.1-2.1 μm and 166-261 nm, respectively, for all three nano-powders, which were smaller than those of the VS (MMAD: 3.3-6.0 μm and NMD: 156-462 nm), and the RD (MMAD: 5.2-11.2 μm and NMD: 198-479 nm). For nano-particles (electric mobility diameter < 100 nm), specific mass concentrations were nearly negligible for all three nano-powders and test methods. Specific number concentrations of nano-particles were low for the RD tester but were elevated when more energetic VS and SSPD testers were used. The quantitative size and concentration data obtained in this study is useful to elucidate the field emission and personal exposure data in the future provided that particle loss in the generation system is carefully assessed.

Triptolide Attenuates Endotoxin- and Staphylococcal Exotoxin-Induced T-Cell Proliferation and Production of Cytokines and Chemokines

DTIC Science & Technology

2005-02-01

were from Sigma (St. Louis, MO, USA). Cell Culture Human PBMC were isolated by Ficoll-Hypaque density gradient centri- fugation of heparinized blood...Cytotoxicity was measured by the uptake of trypan blue . T-cell proliferation was assayed with PBMC (105 cells/well) that were plated in triplicate with...concentration range used in these studies (1–30 nM), as confirmed by trypan blue dye exclusion test. However, at 100 nM triptolide, 20% of PBMC took up

LABEL-FREE DETECTION OF Pb2+ USING SPECIFIC DNAZYME AND UNMODIFIED Au NANOPARTICLE PROBE

NASA Astrophysics Data System (ADS)

Li, Chengyong; Zhao, Zike; Liu, Yaoqian; Lv, Lulu; Qi, Bing; Lin, Haixia; He, Lei; Sun, Shengli

A simple and sensitive Pb2+ sensor is developed based on label-free 17E DNAzyme and unmodified Au nanoparticles. On this basis, Pb2+ concentration can be judged according to the color variation of Au nanoparticles. The detection limit is 100nM and linear range is 100nM-16μM. It can serve as a measurement tool for Pb2+ rapid detection, which provides reference for the development of sensors in environmental monitoring and food safety.

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

Santos, J. F. M. dos; Terra, I. A. A.; Nunes, L. A. O.

Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb{sup 3+}-doped low silica calcium aluminosilicate glasses are analyzed for UV (λ{sub exc} = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb{sup 3+} concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5–15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two ordersmore » of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb{sup 3+} concentrations. Cooperative upconversion from a pair of excited ions ({sup 5}D{sub 3}:{sup 5}D{sub 3} or {sup 5}D{sub 3}:{sup 5}D{sub 4}) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.« less

Fabrication of Ta nanoparticles induced by nanosecond laser ablation in ethanol: the study of laser fluence effects

NASA Astrophysics Data System (ADS)

Azadi Kenari, Fariba; Moniri, Samira; Hantehzadeh, Mohammad Reza; Dorranian, Davoud; Ghoranneviss, Mahmood

2018-05-01

Tantalum nanoparticles (Ta NPs) were synthesized in ethanol solution by ablation with a 1064 nm Nd:YAG laser. Prepared NPs were investigated by UV-visible absorption spectroscopy, Transmission electron microscopy, X-ray diffraction and Photoluminescence measurement. The average sizes of NPs were calculated to be in the range of 12-18 nm. From the UV-visible studies, the plasmon peak position of Ta NPs was observed in the spectral range of 206-208 nm. The XRD spectra clearly showed the crystalline structure of NPs and various peaks of Ta and Ta2O5. Moreover, the UV region in the PL spectrum included the free exciton and the bound exciton emission correlated with the defect concentration. In fact, the laser ablation in the organic and inorganic solvents is a strong technique to obtain some NPs with particular structures, which are impossible to produce by conventional methods.

Note: Evaluation of slurry particle size analyzers for chemical mechanical planarization process

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

Jang, Sunjae; Kulkarni, Atul; Qin, Hongyi

In the chemical mechanical planarization (CMP) process, slurry particle size is important because large particles can cause defects. Hence, selection of an appropriate particle measuring system is necessary in the CMP process. In this study, a scanning mobility particle sizer (SMPS) and dynamic light scattering (DLS) were compared for particle size distribution (PSD) measurements. In addition, the actual particle size and shape were confirmed by transmission electron microscope (TEM) results. SMPS classifies the particle size according to the electrical mobility, and measures the particle concentration (single particle measurement). On the other hand, the DLS measures the particle size distribution bymore » analyzing scattered light from multiple particles (multiple particle measurement). For the slurry particles selected for evaluation, it is observed that SMPS shows bi-modal particle sizes 30 nm and 80 nm, which closely matches with the TEM measurements, whereas DLS shows only single mode distribution in the range of 90 nm to 100 nm and showing incapability of measuring small particles. Hence, SMPS can be a better choice for the evaluation of CMP slurry particle size and concentration measurements.« less

Determination of picomolar concentrations of carbonyl compounds in natural waters, including seawater, by liquid chromatography

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

Kieber, R.; Mopper, K.

1990-10-01

Low molecular weight carbonyl compounds in natural waters were determined at picomolar to nanomolar levels by derivatization with 2,4-dinitrophenylhydrazine followed by liquid chromatography. The uniqueness of the method is attributed to the extremely low blanks obtained and the minimal sample preparation involved. The detection limit for direct injection of derivatized natural water samples is 0.5 nM for aldehydes and 5 nM for ketones with a precision of {approximately}7% RSD at the 30 nM level for aldehydes. The detection limit can be further lowered by using off-line cartridge enrichment in which derivatized natural water is passed through a C18 extraction cartridge.more » Recoveries for the enrichment method were 95-105% for a sample volume of 20 mL and for concentrations of carbonyl compounds in the 1-30 nM range. A field procedure for storage of derivatized sample extracts for extended periods is also presented. Applications of enrichment and sample storage techniques to marine and estuarine waters are presented.« less

Dispersion-compensating photonic crystal fiber with wavelength tunability based on a modified dual concentric core structure

NASA Astrophysics Data System (ADS)

Chen, Nan; Zhang, Xuedian; Nie, Fukun; Lu, Xinglian; Chang, Min

2018-07-01

We present a 5-layer air-hole dispersion-compensating photonic crystal fiber (PCF) with a modified dual concentric core structure, based on central rod doping. The finite element method (FEM) was used to investigate the structure numerically. If the structural parameters remain unchanged, a high degree of linear correlation between the central rod refractive index and the operating wavelength can be achieved in the wavelength range of 1.5457-1.5857 μm, which suggests that the operating wavelength can be determined by the refractive index of the centre rod. A negative dispersion coefficient between -5765.2 ps/km/nm and -6115.8 ps/km/nm was obtained by calculation and within the bandwidth of 108 nm (1.515-1.623 μm) around 1.55 μm, a dispersion coefficient of -3000 ps/km/nm can be ensured for compensation. In addition, this proposed PCF also has the advantage of low confinement loss, between 0.00011 and 0.00012 dB/m, and ease of fabrication with existing technology. The proposed PCF has good prospects in dispersion-compensating applications.

Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity

NASA Astrophysics Data System (ADS)

Gunthe, S. S.; King, S. M.; Rose, D.; Chen, Q.; Roldin, P.; Farmer, D. K.; Jimenez, J. L.; Artaxo, P.; Andreae, M. O.; Martin, S. T.; Pöschl, U.

2009-02-01

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. We have measured and characterized CCN at water vapor supersaturations in the range of S=0.10-0.82% in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia. The effective hygroscopicity parameters describing the influence of chemical composition on the CCN activity of aerosol particles varied in the range of κ=0.05-0.45. The overall median value of κ≍0.15 was only half of the value typically observed for continental aerosols in other regions of the world. Aitken mode particles were less hygroscopic than accumulation mode particles (κ≍0.1 at D≍50 nm; κ≍0.2 at D≍200 nm). The CCN measurement results were fully consistent with aerosol mass spectrometry (AMS) data, which showed that the organic mass fraction (Xm,org) was on average as high as ~90% in the Aitken mode (D≤100 nm) and decreased with increasing particle diameter in the accumulation mode (~80% at D≍200 nm). The κ values exhibited a close linear correlation with Xm,org and extrapolation yielded the following effective hygroscopicity parameters for organic and inorganic particle components: κorg≍0.1 which is consistent with laboratory measurements of secondary organic aerosols and κinorg≍0.6 which is characteristic for ammonium sulfate and related salts. Both the size-dependence and the temporal variability of effective particle hygroscopicity could be parameterized as a function of AMS-based organic and inorganic mass fractions (κp=0.1 Xm,org+0.6 Xm,inorg), and the CCN number concentrations predicted with κp were in fair agreement with the measurement results. The median CCN number concentrations at S=0.1-0.82% ranged from NCCN,0.10≍30 cm-3 to NCCN,0.82≍150 cm-3, the median concentration of aerosol particles larger than 30 nm was NCN,30≍180 cm-3, and the corresponding integral CCN efficiencies were in the range of NCCN,0.10/NCN,30≍0.1 to NCCN,0.82/NCN,30≍0.8. Although the number concentrations and hygroscopicity parameters were much lower, the integral CCN efficiencies observed in pristine rainforest air were similar to those in highly polluted mega-city air. Moreover, model calculations of NCCN,S with a global average value of κ=0.3 led to systematic overpredictions, but the relative deviations exceeded ~50% only at low water vapor supersaturation (0.1%) and low particle number concentrations (≤100 cm-3). These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. Depending on the required and applicable level of detail, the information and parameterizations presented in this paper should enable efficient description of the CCN properties of pristine tropical rainforest aerosols in detailed process models as well as in large-scale atmospheric and climate models.

Silver metal nanoparticles study for biomedical and green house applications

NASA Astrophysics Data System (ADS)

Rauwel, E.; Simón-Gracia, L.; Guha, M.; Rauwel, P.; Kuunal, S.; Wragg, D.

2017-02-01

Metallic nanoparticles (MNP) with diameters ranging from 2 to 100nm have received extensive attention during the past decades due to their many potential applications. This paper presents a structural and cytotoxicity study of silver metal nanoparticles targeted towards biomedical applications. Spherical Ag MNPs of diameter from 20 to 50 nm have been synthesized. The encapsulation of Ag MNPs inside pH-sensitive polymersomes has been also studied for the development of biomedical applications. A cytotoxicity study of the Ag MNPs against primary prostatic cancer cell line (PPC-1) has demonstrated a high mortality rate for concentrations ranging from 100 to 200mg/L. The paper will discuss the potential for therapeutic treatments of these Ag MNPs.

Structure Formation in Salt-Free Solutions of Amphiphilic Sulfonated Polyelectrolytes

NASA Astrophysics Data System (ADS)

Bockstaller, Michael; Koehler, Werner

2000-03-01

Self-assembled systems have long attracted attention due to their practical importance in many technical and biological fields. Dodecyl-substituted poly(para-phenylen)sulfonates (abbreviated PPPS) are highly charged polyelectrolytes which in the uncharged state have been investigated extensively and an intrinsic persistence length of 15 nm has been reported. Due to their hydrophobic side chains, PPPS are compatible with water only as micellar aggregates and tend to form supramolecular structures even at concentrations as low as 10-5mol_mon.units/l. Because of the rodlike conformation of PPPS, this self-assembly leads to aggregates of anisotropic shape. Therefore, depolarized light scattering was employed to yield complementary information about structure and dynamics of these complex fluids. Aqueous solutions of PPPS at room temperature undergo a structural transition at a critical concentration of c_crit.=0.016 g/l. This transition is characterized by a strong increase of scattered intensity in forward direction and dynamic depolarized scattering. Above c_crit. the cylindrical micelles (L=310 nm, d=3.1 nm, N_radial=12) self assembly into large ellipsoidal clusters of size in the μ m range. Due to the strong increase of depolarized scattered intensity there has to be a preferential orientation of the micelles inside those clusters, which thus represent a lyotropic mesophase. By combining static and dynamic light scattering for the low q-range as well as small angle x-ray scattering for the higher q-range it is possible to determine size and shape of each aggregation step. Decreasing the molecular weight of the PPPS has profound influence on the micellar length and hence on c_crit. which is close to the overlap concentration (c ~ 1/L^3) allowing for the observation of the polyelectrolyte effect.

Size and elemental distributions of nano- to micro-particulates in the geochemically-stratified Great Salt Lake

USGS Publications Warehouse

Diaz, X.; Johnson, W.P.; Fernandez, D.; Naftz, D.L.

2009-01-01

The characterization of trace elements in terms of their apportionment among dissolved, macromolecular, nano- and micro-particulate phases in the water column of the Great Salt Lake carries implications for the potential entry of toxins into the food web of the lake. Samples from the anoxic deep and oxic shallow brine layers of the lake were fractionated using asymmetric flow field-flow fractionation (AF4). The associated trace elements were measured via online collision cell inductively-coupled plasma mass spectrometry (CC-ICP-MS). Results showed that of the total (dissolved + particulate) trace element mass, the percent associated with particulates varied from negligible (e.g. Sb), to greater than 50% (e.g. Al, Fe, Pb). Elements such as Cu, Zn, Mn, Co, Au, Hg, and U were associated with nanoparticles, as well as being present as dissolved species. Particulate-associated trace elements were predominantly associated with particulates larger than 450 nm in size. Among the smaller nanoparticulates (<450 nm), some trace elements (Ni, Zn, Au and Pb) showed higher percent mass (associated with nanoparticles) in the 0.9-7.5 nm size range relative to the 10-250 nm size range. The apparent nanoparticle size distributions were similar between the two brine layers; whereas, important differences in elemental associations to nanoparticles were discerned between the two layers. Elements such as Zn, Cu, Pb and Mo showed increasing signal intensities from oxic shallow to anoxic deep brine, suggesting the formation of sulfide nanoparticles, although this may also reflect association with dissolved organic matter. Aluminum and Fe showed greatly increased concentration with depth and equivalent size distributions that differed from those of Zn, Cu, Pb and Mo. Other elements (e.g. Mn, Ni, and Co) showed no significant change in signal intensity with depth. Arsenic was associated with <2 nm nanoparticles, and showed no increase in concentration with depth, possibly indicating dissolved arsenite. Mercury was associated with <2 nm nanoparticles, and showed greatly increased concentration with depth, possibly indicating association with dissolved organic matter. ?? 2009 Elsevier Ltd.

Retrieval Accuracy Assessment with Gap Detection for Case 2 Waters Chla Algorithms

NASA Astrophysics Data System (ADS)

Salem, S. I.; Higa, H.; Kim, H.; Oki, K.; Oki, T.

2016-12-01

Inland lakes and coastal regions types of Case 2 Waters should be continuously and accurately monitored as the former contain 90% of the global liquid freshwater storage, while the latter provide most of the dissolved organic carbon (DOC) which is an important link in the global carbon cycle. The optical properties of Case 2 Waters are dominated by three optically active components: phytoplankton, non-algal particles (NAP) and color dissolved organic matter (CDOM). During the last three decades, researchers have proposed several algorithms to retrieve Chla concentration from the remote sensing reflectance. In this study, seven algorithms are assessed with various band combinations from multi and hyper-spectral data with linear, polynomial and power regression approaches. To evaluate the performance of the 43 algorithm combination sets, 500,000 remote sensing reflectance spectra are simulated with a wide range of concentrations for Chla, NAP and CDOM. The concentrations of Chla and NAP vary from 1-200 (mg m-3) and 1-200 (gm m-3), respectively, and the absorption of CDOM at 440 nm has the range of 0.1-10 (m-1). It is found that the three-band algorithm (665, 709 and 754 nm) with the quadratic polynomial (3b_665_QP) indicates the best overall performance. 3b_665_QP has the least error with a root mean square error (RMSE) of 0.2 (mg m-3) and a mean absolute relative error (MARE) of 0.7 %. The less accurate retrieval of Chla was obtained by the synthetic chlorophyll index algorithm with RMSE and MARE of 35.8 mg m-3 and 160.4 %, respectively. In general, Chla algorithms which incorporates 665 nm band or band tuning technique performs better than those with 680 nm. In addition, the retrieval accuracy of Chla algorithms with quadratic polynomial and power regression approaches are consistently better than the linear ones. By analyzing Chla versus NAP concentrations, the 3b_665_QP outperforms the other algorithms for all Chla concentrations and NAP concentrations above 40 gm m-3which accounts for 81.3 % of the total combinations of NAP and Chla. In conclusion, these findings provide a reference for algorithm selection based on constituents' concentrations and open the door for developing a classification scheme to retrieve Chla with higher accuracy.

Self-association of caffeine in aqueous solution. Study of dilute solutions by normal and second derivative UV absorption spectroscopy.

NASA Astrophysics Data System (ADS)

Iza, N.; Gil, M.; Montero, J. L.; Morcillo, J.

1988-05-01

The concentration dependence of the spectral parameters of caffeine bands at ˜205 and 273 nm has been studied in aqueous solution by normal and second derivative spectroscopy. The concentration range was 5 x 10 -6 - 5 x 10 -3 M and thirty-five different concentrations were used. Discontinuities in parameter variation of these two bands at ˜7.5 x 10 -5, ˜2 x 10 -4, and ˜1 x 10 -3M were observed as concentration was increased. These "limiting" concentrations define three quite differenciated hyper- or hipochromic effects: the first one can be explained as caffeine-water molecule interaction and the second and third as dimer and (dimer + polymer) stacking, respectively. Apparent self-association constants using the isodesmic model have been obtained K= 160 M -1 (for the second hypochromic effect) and K= 13.6 M -1 (for the third hypochromic effect), for the 273 nm band. It is noteworthy that the three "limiting" concentrations coincide with changes in DNA-caffeine interaction modes (H. Lang , 1976) and biological activity (I.B. Syed , 1976).

LUMOS--A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range.

PubMed

Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio; Larsen, Morten; Borisov, Sergey M; Revsbech, Niels-Peter; Glud, Ronnie N; Canfield, Donald E; Klimant, Ingo

2015-01-01

Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized "sensing chemistry" that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented.

Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

NASA Technical Reports Server (NTRS)

Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

2000-01-01

We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

LUMOS - A Sensitive and Reliable Optode System for Measuring Dissolved Oxygen in the Nanomolar Range

PubMed Central

Lehner, Philipp; Larndorfer, Christoph; Garcia-Robledo, Emilio; Larsen, Morten; Borisov, Sergey M.; Revsbech, Niels-Peter; Glud, Ronnie N.; Canfield, Donald E.; Klimant, Ingo

2015-01-01

Most commercially available optical oxygen sensors target the measuring range of 300 to 2 μmol L-1. However these are not suitable for investigating the nanomolar range which is relevant for many important environmental situations. We therefore developed a miniaturized phase fluorimeter based measurement system called the LUMOS (Luminescence Measuring Oxygen Sensor). It consists of a readout device and specialized “sensing chemistry” that relies on commercially available components. The sensor material is based on palladium(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorphenyl)-porphyrin embedded in a Hyflon AD 60 polymer matrix and has a KSV of 6.25 x 10-3 ppmv-1. The applicable measurement range is from 1000 nM down to a detection limit of 0.5 nM. A second sensor material based on the platinum(II) analogue of the porphyrin is spectrally compatible with the readout device and has a measurement range of 20 μM down to 10 nM. The LUMOS device is a dedicated system optimized for a high signal to noise ratio, but in principle any phase flourimeter can be adapted to act as a readout device for the highly sensitive and robust sensing chemistry. Vise versa, the LUMOS fluorimeter can be used for read out of less sensitive optical oxygen sensors based on the same or similar indicator dyes, for example for monitoring oxygen at physiological conditions. The presented sensor system exhibits lower noise, higher resolution and higher sensitivity than the electrochemical STOX sensor previously used to measure nanomolar oxygen concentrations. Oxygen contamination in common sample containers has been investigated and microbial or enzymatic oxygen consumption at nanomolar concentrations is presented. PMID:26029920

Analytical model of nanoscale junctionless transistors towards controlling of short channel effects through source/drain underlap and channel thickness engineering

NASA Astrophysics Data System (ADS)

Roy, Debapriya; Biswas, Abhijit

2018-01-01

We develop a 2D analytical subthreshold model for nanoscale double-gate junctionless transistors (DGJLTs) with gate-source/drain underlap. The model is validated using well-calibrated TCAD simulation deck obtained by comparing experimental data in the literature. To analyze and control short-channel effects, we calculate the threshold voltage, drain induced barrier lowering (DIBL) and subthreshold swing of DGJLTs using our model and compare them with corresponding simulation value at channel length of 20 nm with channel thickness tSi ranging 5-10 nm, gate-source/drain underlap (LSD) values 0-7 nm and source/drain doping concentrations (NSD) ranging 5-12 × 1018 cm-3. As tSi reduces from 10 to 5 nm DIBL drops down from 42.5 to 0.42 mV/V at NSD = 1019 cm-3 and LSD = 5 nm in contrast to decrement from 71 to 4.57 mV/V without underlap. For a lower tSiDIBL increases marginally with increasing NSD. The subthreshold swing reduces more rapidly with thinning of channel thickness rather than increasing LSD or decreasing NSD.

Emission of OH* and CO2* during the high-temperature oxidation of acetone in reflected shock waves

NASA Astrophysics Data System (ADS)

Tereza, A. M.; Smirnov, V. N.; Vlasov, P. A.; Shumova, V. V.; Garmash, A. A.

2018-01-01

Experimental and kinetic modeling study of the ignition of a stoichiometric mixture of acetone with oxygen diluted by argon was carried out behind reflected shock waves within the temperature range of 1350-1810 K for the total mixture concentration [M 50] ~ 10-5 mol/cm3. Emission signals were recorded simultaneously for three different wavelengths: OH* (λ = 308 nm) and {{{CO}}}2* (λ1 = 365 nm; λ2 = 451 nm). It was revealed that the time it takes to reach the maximum of emission of OH* and {{{CO}}}2* is practically the same over the whole temperature range. At the same time, the emission profiles of {{{CO}}}2* after the maximum was attained, recorded at λ2 = 451 nm, differ noticeably from the profiles recorded at λ1 = 365 nm. For numerical modeling of the emission profiles of OH* and {{{CO}}}2* , the corresponding sets of excitation and quenching reactions available in the literature were used. In the course of our numerical simulations we succeeded in good agreement of our own experimental and simulation results on acetone ignition and the results available in the literature for conditions under consideration.

Characterization of Sulfonated Diels-Alder Poly(phenylene) Membranes for Electrolyte Separators in Vanadium Redox Flow Batteries

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

Tang, Zhijiang; Lawton, Jamie S.; Sun, Che-Nan

2014-09-03

Here, sulfonated Diels-Alder poly(phenylene) (SDAPP) membranes were synthesized and characterized as potential electrolyte separators for vanadium redox flow batteries. The SDAPP membranes studied had ion exchange capacities of 1.4, 1.8 and 2.3 meq/g. Transmission electron microscopy imaging shows that the ionic domains in SDAPP are roughly 0.5 nm in dimension, while Nafion has a hydrophilic phase width of around 5 nm. The sulfuric acid uptake by SDAPP was higher than that for Nafion, but the materials had similar water uptake from solutions of various sulfuric acid concentrations. In equilibration with sulfuric acid concentrations ranging from 0–17.4 mol·kg -1, SDAPP withmore » a IEC of 2.3 meq/g had the highest conductivity, ranging from 0.21 to 0.05 S·cm -1, while SDAPP with a IEC of 1.8 had conductivity close to Nafion 117, ranging from 0.11 to 0.02 S·cm -1. With varying sulfuric acid concentration and temperature, vanadium permeability in SDAPP is positively correlated to the membrane's IEC. The vanadium permeability of SDAPP 2.3 is similar to that of Nafion, but permeability values for SDAPP 1.8 and SDAPP 1.4 are substantially lower. The vanadium permeation decreases with increasing electrolyte sulfuric acid concentration. Lastly, vanadium diffusion activation energy is about 20 kJ·mol -1 in both SDAPP and Nafion.« less

Dissolved sulfide distributions in the water column and sediment pore waters of the Santa Barbara Basin

USGS Publications Warehouse

Kuwabara, J.S.; VanGeen, A.; McCorkle, D.C.; Bernhard, J.M.

1999-01-01

Dissolved sulfide concentrations in the water column and in sediment pore waters were measured by square-wave voltammetry (nanomolar detection limit) during three cruises to the Santa Barbara Basin in February 1995, November-December 1995, and April 1997. In the water column, sulfide concentrations measured outside the basin averaged 3 ?? 1 nM (n = 28) in the 0 to 600 m depth range. Inside the basin, dissolved sulfides increased to reach values of up to 15 nM at depths >400 m. A suite of box cores and multicores collected at four sites along the northeastern flank of the basin showed considerable range in surficial (400 ??M at 10 cm. Decreases in water-column nitrate below the sill depth indicate nitrate consumption (-55 to -137 ??mole m-2 h-1) similar to nearby Santa Monica Basin. Peaks in pore-water iron concentrations were generally observed between 2 and 5 cm depth with shallowest peaks at the 590 m site. These observations, including observations of the benthic microfauna, suggest that the extent to which the sulfide flux, sustained by elevated pore-water concentrations, reaches the water column may be modulated by the abundance of sulfide-oxidizing bacteria in addition to iron redox and precipitation reactions.

Spectral Feature Analysis for Quantitative Estimation of Cyanobacteria Chlorophyll-A

NASA Astrophysics Data System (ADS)

Lin, Yi; Ye, Zhanglin; Zhang, Yugan; Yu, Jie

2016-06-01

In recent years, lake eutrophication caused a large of Cyanobacteria bloom which not only brought serious ecological disaster but also restricted the sustainable development of regional economy in our country. Chlorophyll-a is a very important environmental factor to monitor water quality, especially for lake eutrophication. Remote sensed technique has been widely utilized in estimating the concentration of chlorophyll-a by different kind of vegetation indices and monitoring its distribution in lakes, rivers or along coastline. For each vegetation index, its quantitative estimation accuracy for different satellite data might change since there might be a discrepancy of spectral resolution and channel center between different satellites. The purpose this paper is to analyze the spectral feature of chlorophyll-a with hyperspectral data (totally 651 bands) and use the result to choose the optimal band combination for different satellites. The analysis method developed here in this study could be useful to recognize and monitor cyanobacteria bloom automatically and accrately. In our experiment, the reflectance (from 350nm to 1000nm) of wild cyanobacteria in different consistency (from 0 to 1362.11ug/L) and the corresponding chlorophyll-a concentration were measured simultaneously. Two kinds of hyperspectral vegetation indices were applied in this study: simple ratio (SR) and narrow band normalized difference vegetation index (NDVI), both of which consists of any two bands in the entire 651 narrow bands. Then multivariate statistical analysis was used to construct the linear, power and exponential models. After analyzing the correlation between chlorophyll-a and single band reflectance, SR, NDVI respetively, the optimal spectral index for quantitative estimation of cyanobacteria chlorophyll-a, as well corresponding central wavelength and band width were extracted. Results show that: Under the condition of water disturbance, SR and NDVI are both suitable for quantitative estimation of chlorophyll-a, and more effective than the traditional single band model; the best regression models for SR, NDVI with chlorophyll-a are linear and power, respectively. Under the condition without water disturbance, the single band model works the best. For the SR index, there are two optimal band combinations, which is comprised of infrared (700nm-900nm) and blue-green range (450nm-550nm), infrared and red range (600nm-650nm) respectively, with band width between 45nm to 125nm. For NDVI, the optimal band combination includes the range from 750nm to 900nm and 700nm to 750nm, with band width less than 30nm. For single band model, band center located between 733nm-935nm, and its width mustn't exceed the interval where band center located in. This study proved , as for SR or NDVI, the centers and widths are crucial factors for quantitative estimating chlorophyll-a. As for remote sensor, proper spectrum channel could not only improve the accuracy of recognizing cyanobacteria bloom, but reduce the redundancy of hyperspectral data. Those results will provide better reference for designing the suitable spectrum channel of customized sensors for cyanobacteria bloom monitoring at a low altitude. In other words, this study is also the basic research for developing the real-time remote sensing monitoring system with high time and high spatial resolution.

Duplexed sandwich immunoassays on a fiber-optic microarray.

PubMed

Rissin, David M; Walt, David R

2006-03-30

In this paper, we describe a duplexed imaging optical fiber array-based immunoassay for immunoglobulin A (IgA) and lactoferrin. To fabricate the individually addressable array, microspheres were functionalized with highly specific monoclonal antibodies. The microspheres were loaded in microwells etched into the distal face of an imaging optical fiber bundle. Two microsphere-based sandwich immunoassays were developed to simultaneously detect IgA and lactoferrin, two innate immune system proteins found in human saliva. Individual microspheres could be interrogated for the simultaneous measurement of both proteins. The working concentration range for IgA detection was between 700 pM and 100 nM, while the working concentration range for lactoferrin was between 385 pM and 10 nM. The cross-reactivity between detection antibodies and their non-specific targets was relatively low in comparison to the signal generated by the specific binding with their targets. These results suggest that the degree of multiplexing on this fiber-optic array platform can be increased beyond a duplex.

Mesquite Gum as a Novel Reducing and Stabilizing Agent for Modified Tollens Synthesis of Highly Concentrated Ag Nanoparticles

PubMed Central

Moreno-Trejo, Maira Berenice; Sánchez-Domínguez, Margarita

2016-01-01

The synthesis that is described in this study is for the preparation of silver nanoparticles of sizes ranging from 10 nm to 30 nm with a defined shape (globular), confirmed by UV-vis, SEM, STEM and DLS analysis. This simple and favorable one-step modified Tollens reaction does not require any special equipment or other stabilizing or reducing agent except for a solution of purified mesquite gum, and it produces aqueous colloidal dispersions of silver nanoparticles with a stability that exceeds three months, a relatively narrow size distribution, a low tendency to aggregate and a yield of at least 95% for all cases. Reaction times are between 15 min and 60 min to obtain silver nanoparticles in concentrations ranging from 0.1 g to 3 g of Ag per 100 g of reaction mixture. The proposed synthetic method presents a high potential for scale-up, since its production capacity is rather high and the methodology is simple. PMID:28773938

Fabrication of Titania Nanotubes for Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Dzilal, A. A.; Muti, M. N.; John, O. D.

2010-03-01

Detection of hydrogen is needed for industrial process control and medical applications where presence of hydrogen indicates different type of health problems. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to fabricate good quality titania nanotubes suitable for hydrogen sensing applications. The fabrication method used is anodizing method. The anodizing parameters namely the voltage, time duration, concentration of hydrofluoric acid in water, separation between the electrodes and the ambient temperature are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes. The highly ordered porous titania nanotubes produced by this method are in tabular shape and have good uniformity and alignment over large areas. From the investigation done, certain set of anodizing parameters have been found to produce good quality titania nanotubes with diameter ranges from 47 nm to 94 nm.

Particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist Route "Liczyrzepa" Mine in Kowary Adit

NASA Astrophysics Data System (ADS)

Wołoszczuk, Katarzyna; Skubacz, Krystian

2018-01-01

Central Laboratory for Radiological Protection, in cooperation with Central Mining Institute performed measurements of radon concentration in air, potential alpha energy concentration (PAEC), particle size distribution of the radon progeny and ambient aerosols in the Underground Tourist-Educational Route "Liczyrzepa" Mine in Kowary Adit. A research study was developed to investigate the appropriate dose conversion factors for short-lived radon progeny. The particle size distribution of radon progeny was determined using Radon Progeny Particle Size Spectrometer (RPPSS). The device allows to receive the distribution of PAEC in the particle size range from 0.6 nm to 2494 nm, based on their activity measured on 8 stages composed of impaction plates or diffusion screens. The measurements of the ambient airborne particle size distribution were performed in the range from a few nanometres to about 20 micrometres using Aerodynamic Particle Sizer (APS) spectrometer and the Scanning Mobility Particle Sizer Spectrometer (SMPS).

Templated Sphere Phase Liquid Crystals for Tunable Random Lasing

PubMed Central

Chen, Ziping; Hu, Dechun; Chen, Xingwu; Zeng, Deren; Lee, Yungjui; Chen, Xiaoxian; Lu, Jiangang

2017-01-01

A sphere phase liquid crystal (SPLC) composed of three-dimensional twist structures with disclinations among them exists between isotropic phase and blue phase in a very narrow temperature range, about several degrees centigrade. A low concentration polymer template is applied to improve the thermal stability of SPLCs and broadens the temperature range to more than 448 K. By template processing, a wavelength tunable random lasing is demonstrated with dye doped SPLC. With different polymer concentrations, the reconstructed SPLC random lasing may achieve more than 40 nm wavelength continuous shifting by electric field modulation. PMID:29140283

Interaction of chromatin with NaCl and MgCl2. Solubility and binding studies, transition to and characterization of the higher-order structure.

PubMed

Ausio, J; Borochov, N; Seger, D; Eisenberg, H

1984-08-15

Chicken erythrocyte chromatin containing histones H1 and H5 was carefully separated into a number of well-characterized fractions. A distinction could be made between chromatin insoluble in NaCl above about 80 mM, and chromatin soluble at all NaCl concentrations. Both chromatin forms were indistinguishable electrophoretically and both underwent the transition from the low salt "10 nm" coil to the "30 nm" higher-order structure solenoid by either raising the MgCl2 concentration to about 0.3 mM or the NaCl concentration to about 75 mM. The transitions were examined in detail by elastic light-scattering procedures. It could be shown that the 10 nm form is a flexible coil. For the 30 nm solenoid, the assumption of a rigid cylindrical structure was in good agreement with 5.7 nucleosomes per helical turn. However, disagreement of calculated frictional parameters with values derived from quasielastic light-scattering and sedimentation introduced the possibility that the higher-order structure, under these conditions, is more extended, flexible, or perhaps a mixture of structures. Values for density and refractive index increments of chromatin are also given. To understand the interaction of chromatin with NaCl and with MgCl2, a number of experiments were undertaken to study solubility, precipitation, conformational transitions and binding of ions over a wide range of experimental conditions, including chromatin concentration.

Single Nanochannel-Aptamer-Based Biosensor for Ultrasensitive and Selective Cocaine Detection.

PubMed

Wang, Jian; Hou, Jue; Zhang, Huacheng; Tian, Ye; Jiang, Lei

2018-01-17

Ultrasensitive and selective detection of molecules at nano or sub-nanomolar level is very important for many areas such as early diagnosis and drug testing. Herein, we report a high-sensitive cocaine sensor based on a single nanochannel coupled with DNA aptamers. The single nanochannel-aptamer-based biosensor can recognize cocaine molecules with an excellent sensitivity and good selectivity. A linear relationship between target cocaine concentration and output ionic current is obtained in a wide concentration range of cocaine from 1 nM to 10 μM. The cocaine sensor also shows a detection limit down to 1 nM. This study provides a new avenue to develop new nanochannel-aptamer-based biosensors for rapid and ultratrace detection of a variety of illicit drugs.

Plasmonic rainbow rings induced by white radial polarization.

PubMed

Lan, Tzu-Hsiang; Chung, Yi-Kuan; Li, Jie-En; Tien, Chung-Hao

2012-04-01

This Letter presents a scheme to embed both angular/spectral surface plasmon resonance (SPR) in a unique far-field rainbow feature by tightly focusing (effective NA=1.45) a polychromatic radially polarized beam on an Au (20 nm)/SiO2 (500 nm)/Au (20 nm) sandwich structure. Without the need for angular or spectral scanning, the virtual spectral probe snapshots a wide operation range (n=1-1.42; λ=400-700 nm) of SPR excitation in a locally nanosized region. Combined with the high-speed spectral analysis, a proof-of-concept scenario was given by monitoring the NaCl liquid concentration change in real time. The proposed scheme will certainly has a promising impact on the development of objective-based SPR sensor and biometric studies due to its rapidity and versatility.

Optical absorption enhancement in silicon nanowire arrays with a large lattice constant for photovoltaic applications.

PubMed

Lin, Chenxi; Povinelli, Michelle L

2009-10-26

In this paper, we use the transfer matrix method to calculate the optical absorptance of vertically-aligned silicon nanowire (SiNW) arrays. For fixed filling ratio, significant optical absorption enhancement occurs when the lattice constant is increased from 100 nm to 600 nm. The enhancement arises from an increase in field concentration within the nanowire as well as excitation of guided resonance modes. We quantify the absorption enhancement in terms of ultimate efficiency. Results show that an optimized SiNW array with lattice constant of 600 nm and wire diameter of 540 nm has a 72.4% higher ultimate efficiency than a Si thin film of equal thickness. The enhancement effect can be maintained over a large range of incidence angles.

Optoelectronic Characterization of Infrared Photodetector Fabricated on Ge-on-Si Substrate.

PubMed

Khurelbaatar, Zagarzusem; Kil, Yeon-Ho; Kim, Taek Sung; Shim, Kyu-Hwan; Hong, Hyobong; Choi, Chel-Jong

2015-10-01

We report on the optoelectronic characterization of Ge p-i-n infrared photodetector fabricated on Ge-on-Si substrate using rapid thermal chemical vapor deposition (RTCVD). The phosphorous doping concentration and the root mean square (RMS) surface roughness of epitaxial layer was estimated to be 2 x 10(18) cm(-3) and 1.2 nm, respectively. The photodetector were characterized with respect to their dark, photocurrent and responsivities in the wavelength range of 1530-1630 nm. At 1550 nm wavelength, responsivity of 0.32 A/W was measured for a reverse bias of 1 V, corresponding to 25% external quantum efficiency, without an optimal antireflection coating. Responsivity drastically reduced from 1560 nm wavelength which could be attributed to decreased absorption of Ge at room temperature.

Electrochemical Detection of Dopamine via Assisted Ion Transfer at Nanopipet Electrode Using Cyclic Voltammetry.

PubMed

Colombo, Michelle L; McNeil, Swami; Iwai, Nicholas; Chang, Albert; Shen, Mei

2016-01-01

We present here the detection of dopamine (DA) at nanopipet electrodes with radii of hundreds of nanometers ranging from 160 nm to 480 nm. Dibenzo-18-crown-6 (DB18C6) was employed as an ionophore to facilitate DA transfer, resulting in a half-wave transfer potential, E 1/2, DA , of -0.322 (±0.020) V vs. E 1/2, TBA . Well-defined steady-state sigmoidal cyclic voltammograms were observed for the transfer of DA. High resolution scanning electron microscopy was used to measure the size and taper angle of the nanopipet electrodes. The detection is linear with concentration of DA ranging from 0.25 mM to 2 mM; calculated diffusion coefficient at nanopipet electrodes with above mentioned sizes is 4.87 (±0.28) × 10 -10 m 2 /s. The effect of the common interferent ascorbic acid on DA detection with nanopipet electrodes was evaluated, where DA detection still shows linear behavior with well-defined sigmoidal CVs with E 1/2, DA being -0.328 (±0.029) V vs. E 1/2, TBA . The diffusion coefficient for DA transfer in MgCl 2 with the presence of 2 mM AA was measured to be 1.93 (±0.59) × 10 -10 m 2 /s on nanoelectrodes with radii from 161 nm to 263 nm, but the physiological concentration of 0.1 mM AA had no effect on DA's diffusion coefficient.

Dynamic light scattering for the characterization and counting of extracellular vesicles: a powerful noninvasive tool

NASA Astrophysics Data System (ADS)

Palmieri, Valentina; Lucchetti, Donatella; Gatto, Ilaria; Maiorana, Alessandro; Marcantoni, Margherita; Maulucci, Giuseppe; Papi, Massimiliano; Pola, Roberto; De Spirito, Marco; Sgambato, Alessandro

2014-09-01

Extracellular vesicles (EVs) are cell-to-cell shuttles that have recently drawn interest both as drug delivery platforms and disease biomarkers. Despite the increasingly recognized relevance of these vesicles, their detection, and characterization still have several technical drawbacks. In this paper, we accurately assess the size distribution and concentration of EVs by using a high-throughput non-perturbative technique such as Dynamic Light Scattering (DLS). The vesicle radii distribution, as further confirmed by Atomic Force Microscopy experiments, ranges from 10 to 80 nm and appears very asymmetric towards larger radii with a main peak at roughly 30 nm. By combining DLS and Bradford assay, we also demonstrate the feasibility of recovering the concentration and its distribution of proteins contained inside vesicles. The sensitivity of our approach allows to detect protein concentrations as low as 0.01 mg/ml.

Spatial variability of total dissolved copper and copper speciation in the inshore waters of Bermuda.

PubMed

Oldham, V E; Swenson, M M; Buck, K N

2014-02-15

Total dissolved copper (Cu) and Cu speciation were examined from inshore waters of Bermuda, in October 2009 and July-August 2010, to determine the relationship between total dissolved Cu, Cu-binding ligands and bioavailable, free, hydrated Cu(2+) concentrations. Speciation was performed using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV). Mean total dissolved Cu concentrations ranged from 1.4 nM to 19.2 nM, with lowest concentrations at sites further from shore, consistent with previous measurements in the Sargasso Sea, and localized Cu enrichment inshore in enclosed harbors. Ligand concentrations exceeded dissolved [Cu] at most sites, and [Cu(2+)] were correspondingly low at those sites, typically <10(-13) M. One site, Hamilton Harbour, was found to have [Cu] in excess of ligands, resulting in [Cu(2+)] of 10(-10.7) M, and indicating that Cu may be toxic to phytoplankton here. Copyright © 2013 Elsevier Ltd. All rights reserved.

Green synthesis of carbon dots functionalized silver nanoparticles for the colorimetric detection of phoxim.

PubMed

Zheng, Mingda; Wang, Chenge; Wang, Yingying; Wei, Wei; Ma, Shuang; Sun, Xiaohan; He, Jiang

2018-08-01

In this work, Lycii Fructus as raw materials for green synthesis of fluorescent carbon dots (CDs) reduce AgNO 3 . The CDs-AgNPs were synthesized by one-step method. CDs were applied to stabilize AgNPs due to abundant functional groups on the surface of CDs. In presence of phoxim, the dispersed CDs-AgNPs get aggregated and the absorption peak with red shift from 400 nm to 525 nm, resulting in the color changed from yellow to red. Under optimized conditions, the absorbance ratio at A 525 nm /A 400 nm was related linearly to the concentrations of phoxim in the range of 0.1-100 μM. The detection limit was calculated to 0.04 μM, which is lower than maximum residue limits of phoxim in samples in China. The colorimetric sensor was successfully utilized to monitoring phoxim in environmental and fruit samples with good recoveries ranges from 87% to 110.0%. These results showed the sensor had a promising application prospect in real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Fluorescent cooling of objects exposed to sunlight – The ruby example

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

Berdahl, Paul; Chen, Sharon S.; Destaillats, Hugo

Various pigments are used to formulate desirable non-white colors that stay cooler in the sun than alternatives, which is particularly useful for hot climate areas. These cool pigments provide a high near-infrared (NIR) reflectance in the solar infrared range of 700-2500 nm, and also a color specified by a reflectance spectrum in the 400-700 nm visible range. Still cooler materials can be formulated by also utilizing the phenomenon of fluorescence (photoluminescence). Ruby, Al 2O 3 :Cr, is a prime example, with efficient emission in the deep red (~694 nm) and near infrared (700-800 nm). A layer of synthetic ruby crystalsmore » on a white surface having an attractive red color can remain cooler in the sun than conventional red materials. Ruby particles can also be used as a red/pink pigment. Increasing the Cr:Al ratio produces a stronger (darker) pigment but doping above ~3 wt% Cr 2O 3 causes concentration quenching of the fluorescence. The system quantum efficiency for lightly doped ruby-pigmented coatings over white is high, 0.83 ± 0.10.« less

Fe3O4 and metal-organic framework MIL-101(Fe) composites catalyze luminol chemiluminescence for sensitively sensing hydrogen peroxide and glucose.

PubMed

Qian Tang, Xue; Dan Zhang, Yi; Wei Jiang, Zhong; Mei Wang, Dong; Zhi Huang, Cheng; Fang Li, Yuan

2018-03-01

In this work, Fe 3 O 4 and metal-organic framework MIL-101(Fe) composites (Fe 3 O 4 /MIL-101(Fe)) was demonstrated to possess excellent catalytic property to directly catalyze luminol chemiluminescence without extra oxidants. We utilized Fe 3 O 4 /MIL-101(Fe) to develop a ultra-sensitive quantitative analytical method for H 2 O 2 and glucose. The possible mechanism of the chemiluminescence reaction had been investigated. Under optimal conditions, the relative chemiluminescence intensity was linearly proportional to the logarithm of H 2 O 2 concentration in the range of 5-150nM with a limit of detection of 3.7nM (signal-to-noise ratio = 3), and glucose could be linearly detected in the range from 5 to 100nM and the detection limit was 4.9nM (signal-to-noise ratio = 3). Furthermore, the present approach was successfully applied to quantitative determination of H 2 O 2 in medical disinfectant and glucose in human serum samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Photoinitiator Nucleotide for Quantifying Nucleic Acid Hybridization

PubMed Central

Johnson, Leah M.; Hansen, Ryan R.; Urban, Milan; Kuchta, Robert D.; Bowman, Christopher N.

2010-01-01

This first report of a photoinitiator-nucleotide conjugate demonstrates a novel approach for sensitive, rapid and visual detection of DNA hybridization events. This approach holds potential for various DNA labeling schemes and for applications benefiting from selective DNA-based polymerization initiators. Here, we demonstrate covalent, enzymatic incorporation of an eosin-photoinitiator 2′-deoxyuridine-5′-triphosphate (EITC-dUTP) conjugate into surface-immobilized DNA hybrids. Subsequent radical chain photoinitiation from these sites using an acrylamide/bis-acrylamide formulation yields a dynamic detection range between 500pM and 50nM of DNA target. Increasing EITC-nucleotide surface densities leads to an increase in surface-based polymer film heights until achieving a film height plateau of 280nm ±20nm at 610 ±70 EITC-nucleotides/μm2. Film heights of 10–20 nm were obtained from eosin surface densities of approximately 20 EITC-nucleotides/μm2 while below the detection limit of ~10 EITC-nucleotides/μm2, no detectable films were formed. This unique threshold behavior is utilized for instrument-free, visual quantification of target DNA concentration ranges. PMID:20337438

A water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range

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

Pinterich, Tamara; Spielman, Steven R.; Hering, Susanne

We developed a water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range. The WFIMS builds on two established technologies: the fast integrated mobility spectrometer and laminar flow water-based condensation methodology. Inside WFIMS, particles of differing electrical mobility are separated in a drift tube and subsequently enlarged through water condensation. Particle size and concentration are measured via digital imaging at a frame rate of 10 Hz. When we measure particles of different mobilities simultaneously, the WFIMS resolves particle diameters ranging from 8 to 580 nm within 1 s or less. The performance of WFIMS was characterized with differential mobilitymore » analyzer (DMA) classified (NH 4) 2SO 2 particles with diameters ranging from 8 to 265 nm. The mean particle diameters measured by WFIMS were found to be in excellent agreement with DMA centroid diameters. Furthermore, detection efficiency of WFIMS was characterized using a condensation particle counter as a reference and is nearly 100% for particles with diameter greater than 8 nm. In general, measured and simulated WFIMS mobility resolutions are in good agreement. But, some deviations are observed at low particle mobilities, likely due to the non-idealities of the WFIMS electric field.« less

A water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range

DOE PAGES

Pinterich, Tamara; Spielman, Steven R.; Hering, Susanne; ...

2017-06-08

We developed a water-based fast integrated mobility spectrometer (WFIMS) with enhanced dynamic size range. The WFIMS builds on two established technologies: the fast integrated mobility spectrometer and laminar flow water-based condensation methodology. Inside WFIMS, particles of differing electrical mobility are separated in a drift tube and subsequently enlarged through water condensation. Particle size and concentration are measured via digital imaging at a frame rate of 10 Hz. When we measure particles of different mobilities simultaneously, the WFIMS resolves particle diameters ranging from 8 to 580 nm within 1 s or less. The performance of WFIMS was characterized with differential mobilitymore » analyzer (DMA) classified (NH 4) 2SO 2 particles with diameters ranging from 8 to 265 nm. The mean particle diameters measured by WFIMS were found to be in excellent agreement with DMA centroid diameters. Furthermore, detection efficiency of WFIMS was characterized using a condensation particle counter as a reference and is nearly 100% for particles with diameter greater than 8 nm. In general, measured and simulated WFIMS mobility resolutions are in good agreement. But, some deviations are observed at low particle mobilities, likely due to the non-idealities of the WFIMS electric field.« less

Aerosol effects on the UV irradiance in Santiago de Chile

NASA Astrophysics Data System (ADS)

Cordero, R. R.; Seckmeyer, G.; Damiani, A.; Jorquera, J.; Carrasco, J.; Muñoz, R.; Da Silva, L.; Labbe, F.; Laroze, D.

2014-11-01

Santiago de Chile (33°27‧ S-70°41‧ W) is a mid-latitude city of 6 million inhabitants with a complicated surrounding topography. Aerosol extinction in Santiago is determined by the semi-arid local climate, the urban pollution, a regional subsidence thermal inversion layer, and the boundary-layer wind airflow. In this paper we report on spectral measurements of the surface irradiance (at 290-600 nm wavelength range) carried out during 2013 in the heart of the city by using a double monochromator-based spectroradiometer system. These measurements were used to assess the effect of local aerosols, paying particular attention to the ultraviolet (UV) range. We found that the aerosol optical depth (AOD) exhibited variations likely related to changes in the subsidence thermal inversion and in the boundary-layer winds. Although the AOD at 350 nm typically ranged from 0.2 to 0.3, peak values of about 0.7 were measured. The AOD diminished with the wavelength and typically ranged from 0.1 to 0.2 at 550 nm. Our AOD data were found to be consistent with measurements of the particulate matter (PM) mass concentration.

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-12-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of atmospheric remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and comma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications from LEO, GEO, HAP or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at 0.5 nm resolution, suitable for a number of typical DOAS applications.

Stand-off detection of explosives vapors by resonance-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Johansson, Ida; Ceco, Ema; Ehlerding, Anneli; Östmark, Henric

2013-06-01

This paper describes a system for stand-off vapor detection based on Resonant Raman spectroscopy, RRS. The system is a step towards a RRS LIDAR (Light Detection And Ranging) system, capable of detecting vapors from explosives and explosives precursors at long distances. The current system was used to detect the vapor of nitromethane and mononitrotoluene outdoors in the open air, at a stand-off distance of 11-13 meters. Also, the signal dependence upon irradiation wavelength and sample concentration was studied in controlled laboratory conditions. A tunable Optical Parametric Oscillator pumped by an Nd:YAG laser, with a pulse length of 6 ns, was operated in the UV range of interest, 210-400 nm, illuminating the sample vapor. The backscattered Raman signal was collected by a telescope and a roundto- slit optical fiber was used to transmit collected light to the spectrometer with minimum losses. A gated intensified charge-coupled device (ICCD) registered the spectra. The nitromethane cross section was resonance enhanced more than a factor 30 700, when measured at 220 nm, compared to the 532 nm value. The results show that a decrease in concentration can have a positive effect on the sensitivity of the system, due to a decrease in absorption and selfabsorption in the sample.

Magnetic structure in Mn1 -xCoxGe compounds

NASA Astrophysics Data System (ADS)

Altynbaev, E.; Siegfried, S.-A.; Strauß, P.; Menzel, D.; Heinemann, A.; Fomicheva, L.; Tsvyashchenko, A.; Grigoriev, S.

2018-04-01

The magnetic system of the pseudobinary compound Mn1 -xCoxGe has been studied using small-angle neutron scattering and susceptibility measurements. It is found that Mn1 -xCoxGe orders magnetically at low temperatures in the whole concentration range of x ∈[0 /0.9 ] . Four different states of the magnetic structure have been found at low temperatures: the long-range-ordered (LRO) short-period helical magnetic structure at x

Influence of HF acid catalyst concentration on properties of aerogel low-k thin films

NASA Astrophysics Data System (ADS)

Gaikwad, A. S.; Gupta, S. A.; Mahajan, A. M.

2016-08-01

The effect of hydrofluoric acid (HF) catalyst concentration in coating solution on chemical, physical and structural properties of silica aerogel thin films was investigated. The aerogel films were synthesized by using a sol-gel spin coating method followed by aging in ethanol and CO2 supercritical drying. The refractive index (RI) is observed to be reduced from 1.32 to 1.13 and porosity percentage increased from 30.21% to 71.64% in accordance with increasing HF concentration. Deposition of silica aerogel was confirmed from Fourier transform infrared spectroscopy measurement. The nanoporous nature of deposited films was confirmed from field effect scanning electron microscopy and observed pore diameter is in the range of 3.33 to 6.69 nm. The nanoporous nature of the film was also validated from atomic force microscopy and root mean square roughness was observed to be increased from 2.31 nm to 3.2 nm with increasing acid catalyst concentration in the coating solution. The calculated dielectric constant from CV measurement of fabricated metal-insulator-semiconductor structure for the silica aerogel formed at 0.8 ml HF concentration is observed to be 1.73. These deposited nanoporous silica aerogel low-k films with lower k value and smaller pore size have application as interlayer dielectric materials to minimize the disadvantages of porous materials.

Optical Properties of Cu2O Electrodeposited on FTO Substrates: Effects of Cl Concentration

NASA Astrophysics Data System (ADS)

Bouderbala, Ibrahim Yaacoub; Herbadji, Abdelmadjid; Mentar, Loubna; Beniaiche, Abdelkrim; Azizi, Amor

2018-03-01

In this study, cuprous oxide (Cu2O) nanostructures were deposited via electrochemical route from aqueous solution containing different concentrations of copper chloride (CuCl2). The effect of chloride (Cl- ) ions on structural and optical properties was studied. Photocurrent results show that the type of conduction of these nanostructures is affected by adding Cl- ions and changed from p-type to n-type conduction. The x-ray diffraction (XRD) shows that our samples were pure Cu2O with a preferential orientation along the (111) direction. The intensity of (111) peak increases with the increase of Cl- concentration. The optical characterization of Cu2O was studied by analyzing the transmission spectrum measured in normal incidence in the range of 300-1100 nm. The thickness and the refractive index of Cu2O nanostructures were determined using different methods. The optical gap energy ( E g) and associated Urbach energy ( E u) were also calculated. Effectively, the optical gap was estimated from Tauc extrapolation; it was found that it decreases from 2.02 eV to 1.85 eV with the increase in CuCl2 concentration; on the other hand, the thickness of the layers increases from 267 nm to 300 nm.

Time delay and excitation mode induced tunable red/near-infrared to green emission ratio of Er doped BiOCl

NASA Astrophysics Data System (ADS)

Avram, Daniel; Florea, Mihaela; Tiseanu, Ion; Tiseanu, Carmen

2015-09-01

Herein, we report on the emission color tunability of Er doped BiOCl measured under up—conversion as well as x-ray excitation modes. The dependence of red (670 nm) to green emission (543 nm) ratio on Er concentration (1 and 5%), excitation wavelength into different (656.4, 802 and 976 nm) or across single Er absorption levels (965 ÷ 990 nm) and delay after the laser pulse (0.001 ÷ 1 ms) is discussed in terms of ground state absorption/excited state absorption and energy transfer up-conversion mechanisms. A first example of extended Er x-ray emission measured in the range of 500 to 1700 nm shows comparable emission intensities corresponding to 543 nm and 1500 nm based transitions. The present results together with our earlier report on the upconversion emission of Er doped BiOCl excited at 1500 nm, suggest that Er doped BiOCl may be considered an attractive system for optical and x-ray imaging applications.

The effect of pH on the toxicity of zinc oxide nanoparticles to Folsomia candida in amended field soil.

PubMed

Waalewijn-Kool, Pauline L; Ortiz, Maria Diez; Lofts, Stephen; van Gestel, Cornelis A M

2013-10-01

The effect of soil pH on the toxicity of 30 nm ZnO to Folsomia candida was assessed in Dorset field soils with pHCaCl2 adjusted to 4.31, 5.71, and 6.39. To unravel the contribution of particle size and dissolved Zn, 200 nm ZnO and ZnCl2 were tested. Zinc sorption increased with increasing pH, and Freundlich kf values ranged from 98.9 (L/kg)(1/n) to 333 (L/kg)(1/n) for 30 nm ZnO and from 64.3 (L/kg)(1/n) to 187 (L/kg)(1/n) for ZnCl2. No effect of particle size was found on sorption, and little difference was found in toxicity between 30 nm and 200 nm ZnO. The effect on reproduction decreased with increasing pH for all Zn forms, with 28-d median effective concentrations (EC50s) of 553 mg Zn/kg, 1481 mg Zn/kg, and 3233 mg Zn/kg for 30 nm ZnO and 331 mg Zn/kg, 732 mg Zn/kg, and 1174 mg Zn/kg for ZnCl2 at pH 4.31, 5.71, and 6.39, respectively. The EC50s based on porewater Zn concentrations increased with increasing pH for 30 nm ZnO from 4.77 mg Zn/L to 18.5 mg Zn/L, while for ZnCl2 no consistent pH-related trend in EC50s was found (21.0-63.3 mg Zn/L). Porewater calcium levels were 10 times higher in ZnCl2 -spiked soils than in ZnO-spiked soils. The authors' results suggest that the decreased toxicity of ZnCl2 compared with 30 nm ZnO based on porewater concentrations was because of a protective effect of calcium and not a particle effect. © 2013 SETAC.

[Ultraviolet spectrophotometric determination of tenoxicam using iodine solution as reagent].

PubMed

Mândrescu, Mariana; Spac, A F; Dorneanu, V

2009-01-01

For the tenoxicam determination (Nonsteroidal Antiinflammatory Drug - NSAID) it was developed a spectrophotometric method, after the coupling reaction of tenoxicam with iodine, in methanolic medium, with maximum of absorbance at 289 nm. The practical working conditions were established. In the 0.5 divided by 5.0 microg/mL range of tenoxicam concentration, were used 5 x 10(-3) M iodine solution and 0.5 N hydrocloric acid. The stability of product were evaluated for 30 minutes. The developed method was validated. The method showed a good linearity in the range of 0.5 divided 5.0 microg/mL (the correlation coefficient r = 0.9995). The detection limit (LD) was 0.14 microg/mL and the quantification limit (LQ) was 0.49 microg/mL. There were established the precison (RSD = 1.90%) and the accuracy-recovery in the range 97.27 divided by 102.56% with a mean recovery of 99.49%. The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A1%(1 cm,289 nm) = 1770 much higher than tenoxicam in methanol (A1%(1 cm,360 nm) = 323).

Dielectric, optical and mechanical studies of phenolic polyene OH1 organic electrooptic crystal

NASA Astrophysics Data System (ADS)

Bharath, D.; Kalainathan, S.

2014-11-01

2-{3-[2-(4-Hydroxyphenyl) vinyl]-5, 5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile (OH1) phenolic locked polyene organic material has been synthesized by the Knoevenagel condensation method. OH1 single crystals were grown in methanol by a slow evaporation method. In order to avoid the multinucleation and reduce the metastable zone width, phosphoric acid is added in different concentrations. The linear optical property of OH1 crystal has been studied using UV-vis-NIR spectroscopy in the wavelength range 190-1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10-12 m2/W), nonlinear absorption (10-6 m/W) and third order nonlinear susceptibility (10-6 esu) has been studied using a Z-scan technique. Dielectric property of OH1 crystal has been studied in frequency range 50 Hz-5 MHz. Photoluminescence spectrum was recorded using a xenon lamp in the range of 450-700 nm. Laser optical damage threshold of OH1 crystal was obtained (0.62 GW/cm2) using a pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns.

Optical, microphysical, mass and geometrical properties of aged volcanic particles observed over Athens, Greece, during the Eyjafjallajökull eruption in April 2010 through synergy of Raman lidar and sunphotometer measurements

NASA Astrophysics Data System (ADS)

Kokkalis, P.; Papayannis, A.; Amiridis, V.; Mamouri, R. E.; Veselovskii, I.; Kolgotin, A.; Tsaknakis, G.; Kristiansen, N. I.; Stohl, A.; Mona, L.

2013-09-01

Vertical profiles of the optical (extinction and backscatter coefficients, lidar ratio and Ångström exponent), microphysical (mean effective radius, mean refractive index, mean number concentration) and geometrical properties as well as the mass concentration of volcanic particles from the Eyjafjallajökull eruption were retrieved at selected heights over Athens, Greece, using multi-wavelength Raman lidar measurements performed during the period 21-24 April 2010. Aerosol Robotic Network (AERONET) particulate columnar measurements along with inversion schemes were initialized together with lidar observations to deliver the aforementioned products. The well-known FLEXPART (FLEXible PARTicle dispersion model) model used for volcanic dispersion simulations is initiated as well in order to estimate the horizontal and vertical distribution of volcanic particles. Compared with the lidar measurements within the planetary boundary layer over Athens, FLEXPART proved to be a useful tool for determining the state of mixing of ash with other, locally emitted aerosol types. The major findings presented in our work concern the identification of volcanic particles layers in the form of filaments after 7-day transport from the volcanic source (approximately 4000 km away from our site) from the surface and up to 10 km according to the lidar measurements. Mean hourly averaged lidar signals indicated that the layer thickness of volcanic particles ranged between 1.5 and 2.2 km. The corresponding aerosol optical depth was found to vary from 0.01 to 0.18 at 355 nm and from 0.02 up to 0.17 at 532 nm. Furthermore, the corresponding lidar ratios (S) ranged between 60 and 80 sr at 355 nm and 44 and 88 sr at 532 nm. The mean effective radius of the volcanic particles estimated by applying inversion scheme to the lidar data found to vary within the range 0.13-0.38 μm and the refractive index ranged from 1.39+0.009i to 1.48+0.006i. This high variability is most probably attributed to the mixing of aged volcanic particles with other aerosol types of local origin. Finally, the LIRIC (LIdar/Radiometer Inversion Code) lidar/sunphotometric combined inversion algorithm has been applied in order to retrieve particle concentrations. These have been compared with FLEXPART simulations of the vertical distribution of ash showing good agreement concerning not only the geometrical properties of the volcanic particles layers but also the particles mass concentration.

Diurnal pattern in nitrous oxide emissions from a sewage-enriched river.

PubMed

Xia, Yongqiu; Li, Yuefei; Li, Xiaobo; Guo, Miao; She, Dongli; Yan, Xiaoyuan

2013-07-01

Estimates of N2O emission based on limit measurements could be highly inaccurate because of considerable diurnal variations in N2O flux due to rapid transformation of nutrients and diel change of dissolved oxygen (DO). In the present study, the N2O fluxes, dissolved N2O concentrations, and the controlling variables were measured hourly for 3d and night cycles at five sites on a typically sewage-enriched river in the Taihu region. There were no significant diurnal patterns in N2O emissions and dissolved N2O saturation, with respective mean value of 56.1μg N2O-Nm(-2)h(-1) (range=41.1μg N2O-Nm(-2)h(-1) to 87.7μg N2O-Nm(-2)h(-1)) and 813% (range=597-1372%), though distinct diurnal patterns were observed in DO concentration and river chemistry. However, the mean N2O emissions and the mean dissolved N2O saturation during the day (61.7μgNm(-2)h(-1) for N2O fluxes and 0.52μgNL(-1) for dissolved N2O saturation) were significantly higher than those during the night (50.1μgNm(-2)h(-1)for N2O fluxes and 0.44μgNL(-1) for dissolved N2O saturation). Factors controlling the N2O flux were pH, DO, NH4(+),SO4(2-), air temperature, and water temperature. Sampling at 19:00h could well represent the daily average N2O flux at the studied river. Copyright © 2013 Elsevier Ltd. All rights reserved.

The influence of excitation radiation parameters on photosensitized generation of singlet oxygen in water

NASA Astrophysics Data System (ADS)

Il'ina, A. D.; Glazov, A. L.; Semenova, I. V.; Vasyutinskii, O. S.

2016-06-01

Photosensitized generation of singlet oxygen with the aid of Radahlorin® photosensitizer has been investigated. The dependences of the intensity of singlet oxygen phosphorescence and photosensitizer fluorescence on the excitation radiation wavelength in the range of 350-440 nm and on the irradiation dose have been obtained. The dependence of the ratio of the sensitizer fluorescence intensity at about 670 nm to the singlet oxygen phosphorescence intensity at a wavelength of 1270 nm on the excitation radiation wavelength is found to be nonmonotonic and have a minimum near the center of the absorption band on its red wing. The results obtained can be used to monitor the singlet oxygen concentration in solutions.

[Spectrophotometric determination of piroxicam using ferric ferricyanide as reagent].

PubMed

Mândrescu, Mariana; Spac, A F; Dorneanu, V

2009-01-01

For the piroxicam determination (nonsteroidal antiinflammatory drug-NSAID) it was developed a spectrophotometric method, based on the reduction of ferric ferricyanide into ferro-ferricyanide (Prussian Blue), with maximum of absorbance at 760 nm. The practical working conditions were established. In the 0.2 divided by 2.0 microg/mL range of piroxicam concentration, were used the 2 mL of ferric ferricyanide 1 mL of 2N hydrocloric acid. To delay the flocculation of Prussian Blue it was to add a 1 mL solution of sodium lauryl sulfate 1%. After 15 minutes read the absorbance at 760 nm. The developed method was validated. The method showed a good linearity in the range of 0.2 divided by 2.0 microg/mL (the correlation coefficient r = 0.9995). The detection limit (LD) was 0.056 microg/mL and the quantification limit (LQ) was 0.18 microg/mL. There were established the system precision (RSD = 0.25%), the precison (RSD = 1.91%) and the accuracy-recovery in the range 98.21 divided by 104.92% with a mean recovery of 100.91%. The experimental results demonstrated a good sensibility. The specific absorptivity for this method is A(1 cm, 760 nm)(1%) = 4374 much higher than piroxicam in UV (A(1 cm, 330 nm)(1%) = 296)

Fluorescence Studies of Protein Crystallization Interactions

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Smith, Lori; Forsythe, Elizabeth

1999-01-01

We are investigating protein-protein interactions in under- and over-saturated crystallization solution conditions using fluorescence methods. The use of fluorescence requires fluorescent derivatives where the probe does not markedly affect the crystal packing. A number of chicken egg white lysozyme (CEWL) derivatives have been prepared, with the probes covalently attached to one of two different sites on the protein molecule; the side chain carboxyl of ASP 101, within the active site cleft, and the N-terminal amine. The ASP 101 derivatives crystallize while the N-terminal amine derivatives do not. However, the N-terminal amine is part of the contact region between adjacent 43 helix chains, and blocking this site does would not interfere with formation of these structures in solution. Preliminary FRET data have been obtained at pH 4.6, 0.1M NaAc buffer, at 5 and 7% NaCl, 4 C, using the N-terminal bound pyrene acetic acid (PAA, Ex 340 nm, Em 376 nm) and ASP 101 bound Lucifer Yellow (LY, Ex 425 nm, Em 525 nm) probe combination. The corresponding Csat values are 0.471 and 0.362 mg/ml (approximately 3.3 and approximately 2.5 x 10 (exp 5) M respectively), and all experiments were carried out at approximately Csat or lower total protein concentration. The data at both salt concentrations show a consistent trend of decreasing fluorescence yield of the donor species (PAA) with increasing total protein concentration. This decrease is apparently more pronounced at 7% NaCl, consistent with the expected increased intermolecular interactions at higher salt concentrations (reflected in the lower solubility). The estimated average distance between protein molecules at 5 x 10 (exp 6) M is approximately 70 nm, well beyond the range where any FRET can be expected. The calculated RO, where 50% of the donor energy is transferred to the acceptor, for the PAA-CEWL * LY-CEWL system is 3.28 nm, based upon a PAA-CEWL quantum efficiency of 0.41.

Irradiation-induced Ag-colloid formation in ion-exchanged soda-lime glass

NASA Astrophysics Data System (ADS)

Caccavale, F.; De Marchi, G.; Gonella, F.; Mazzoldi, P.; Meneghini, C.; Quaranta, A.; Arnold, G. W.; Battaglin, G.; Mattei, G.

1995-03-01

Ion-exchanged glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1-20% AgNO 3 in NaNO 3, at temperatures varying from 320 to 350°C, and processing times of the order of a few minutes. Irradiations of exchanged samples were subsequently performed by using H +m, He +, N + ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 × 10 15 and 2 × 10 17 ions/cm 2. Most of the samples were treated at current densities lower than 2 μA/cm 2, in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1-10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RBS), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.

Luminescence Mechanism of Carbon Dots by Tailoring Functional Groups for Sensing Fe3+ Ions

PubMed Central

Yu, Jingjing; Liu, Chang; Yuan, Kang; Lu, Zunming; Cheng, Yahui; Li, Lanlan; Jin, Peng; Meng, Fanbin; Liu, Hui

2018-01-01

In this paper, spherical carbon dots (CDs) with distinct compositions and surface states have been successfully synthesized by a facile microwave method. From the fluorescence spectra, several characteristic luminescence features have been observed: surface amino groups are dominant in the whole emission spectra centering at 445 nm, and the fingerprint emissions relevant to the impurity levels formed by some groups related to C and N elements, including C-C/C=C (intrinsic C), C-N (graphitic N), N-containing heterocycles (pyridine N) and C=O groups, are located around 305 nm, 355 nm, 410 nm, and 500 nm, respectively. Those fine luminescence features could be ascribed to the electron transition among various trapping states within the band structure caused by different chemical bonds in carbon cores, or functional groups attached to the CDs’ surfaces. According to the theoretical calculations and experimental results, a scheme of the band structure has been proposed to describe the positions of those trapping states within the band gap. Additionally, it has also been observed that the emission of CDs is sensitive to the concentration of Fe3+ ions with a linear relation in the range of Fe3+ concentration from 12.5 to 250 μM. PMID:29649110

Tissue distribution and acute toxicity of silver after single intravenous administration in mice: nano-specific and size-dependent effects.

PubMed

Recordati, Camilla; De Maglie, Marcella; Bianchessi, Silvia; Argentiere, Simona; Cella, Claudia; Mattiello, Silvana; Cubadda, Francesco; Aureli, Federica; D'Amato, Marilena; Raggi, Andrea; Lenardi, Cristina; Milani, Paolo; Scanziani, Eugenio

2016-02-29

Silver nanoparticles (AgNPs) are an important class of nanomaterials used as antimicrobial agents for a wide range of medical and industrial applications. However toxicity of AgNPs and impact of their physicochemical characteristics in in vivo models still need to be comprehensively characterized. The aim of this study was to investigate the effect of size and coating on tissue distribution and toxicity of AgNPs after intravenous administration in mice, and compare the results with those obtained after silver acetate administration. Male CD-1(ICR) mice were intravenously injected with AgNPs of different sizes (10 nm, 40 nm, 100 nm), citrate-or polyvinylpyrrolidone-coated, at a single dose of 10 mg/kg bw. An equivalent dose of silver ions was administered as silver acetate. Mice were euthanized 24 h after the treatment, and silver quantification by ICP-MS and histopathology were performed on spleen, liver, lungs, kidneys, brain, and blood. For all particle sizes, regardless of their coating, the highest silver concentrations were found in the spleen and liver, followed by lung, kidney, and brain. Silver concentrations were significantly higher in the spleen, lung, kidney, brain, and blood of mice treated with 10 nm AgNPs than those treated with larger particles. Relevant toxic effects (midzonal hepatocellular necrosis, gall bladder hemorrhage) were found in mice treated with 10 nm AgNPs, while in mice treated with 40 nm and 100 nm AgNPs lesions were milder or negligible, respectively. In mice treated with silver acetate, silver concentrations were significantly lower in the spleen and lung, and higher in the kidney than in mice treated with 10 nm AgNPs, and a different target organ of toxicity was identified (kidney). Administration of the smallest (10 nm) nanoparticles resulted in enhanced silver tissue distribution and overt hepatobiliary toxicity compared to larger ones (40 and 100 nm), while coating had no relevant impact. Distinct patterns of tissue distribution and toxicity were observed after silver acetate administration. It is concluded that if AgNPs become systemically available, they behave differently from ionic silver, exerting distinct and size-dependent effects, strictly related to the nanoparticulate form.

Highly sensitive and selective determination of fluorine ion by graphene oxide/nanogold resonance Rayleigh scattering-energy transfer analytical platform.

PubMed

Liang, Aihui; Peng, Jing; Liu, Qingye; Wen, Guiqing; Lu, Zhujun; Jiang, Zhiliang

2015-08-15

In pH 4.0 acetate buffer solution, fluorine ions react with fluorine reagent (FR) and La(III) to generate blue ternary complex that exhibited strong absorption at about 370 nm. Upon addition of graphene oxide/nanogold (GO/NG) as resonance Rayleigh scattering (RRS) spectral probe with strong RRS peak at 370 nm, the color changed to gray, and the RRS intensity decreased with the increase of fluorine ion concentration due to the RRS energy transfer (RRSET) from GO/NG to the complex. Under the selected condition, the decreased RRS peak ΔI370 nm was linear to fluorine ion concentration in the range of 6.0 × 10(-8)-1.3 × 10(-5)mol/L, with a detection limit of 3.0 × 10(-8)mol/L F(-). This RRSET method was applied to the analysis of fluorine in toothpaste and water samples, with satisfactory results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detection of the level of fluoride in the commercially available toothpaste using laser induced breakdown spectroscopy with the marker atomic transition line of neutral fluorine at 731.1 nm

NASA Astrophysics Data System (ADS)

Gondal, M. A.; Maganda, Y. W.; Dastageer, M. A.; Al Adel, F. F.; Naqvi, A. A.; Qahtan, T. F.

2014-04-01

Fourth harmonic of a pulsed Nd:YAG laser (wavelength 266 nm) in combination with high resolution spectrograph equipped with Gated ICCD camera has been employed to design a high sensitive analytical system. This detection system is based on Laser Induced Breakdown Spectroscopy and has been tested first time for analysis of semi-fluid samples to detect fluoride content present in the commercially available toothpaste samples. The experimental parameters were optimized to achieve an optically thin and in local thermo dynamic equilibrium plasma. This improved the limits of detection of fluoride present in tooth paste samples. The strong atomic transition line of fluorine at 731.102 nm was used as the marker line to quantify the fluoride concentration levels. Our LIBS system was able to detect fluoride concentration levels in the range of 1300-1750 ppm with a detection limit of 156 ppm.

The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

PubMed Central

Kant, Krishna; Priest, Craig; Shapter, Joe G.; Losic, Dusan

2014-01-01

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

Measuring milk fat content by random laser emission

NASA Astrophysics Data System (ADS)

Abegão, Luis M. G.; Pagani, Alessandra A. C.; Zílio, Sérgio C.; Alencar, Márcio A. R. C.; Rodrigues, José J.

2016-10-01

The luminescence spectra of milk containing rhodamine 6G are shown to exhibit typical signatures of random lasing when excited with 532 nm laser pulses. Experiments carried out on whole and skim forms of two commercial brands of UHT milk, with fat volume concentrations ranging from 0 to 4%, presented lasing threshold values dependent on the fat concentration, suggesting that a random laser technique can be developed to monitor such important parameter.

Measuring milk fat content by random laser emission.

PubMed

Abegão, Luis M G; Pagani, Alessandra A C; Zílio, Sérgio C; Alencar, Márcio A R C; Rodrigues, José J

2016-10-12

The luminescence spectra of milk containing rhodamine 6G are shown to exhibit typical signatures of random lasing when excited with 532 nm laser pulses. Experiments carried out on whole and skim forms of two commercial brands of UHT milk, with fat volume concentrations ranging from 0 to 4%, presented lasing threshold values dependent on the fat concentration, suggesting that a random laser technique can be developed to monitor such important parameter.

Laser photolysis of caged compounds at 405 nm: photochemical advantages, localisation, phototoxicity and methods for calibration.

PubMed

Trigo, Federico F; Corrie, John E T; Ogden, David

2009-05-30

Rapid, localised photolytic release of neurotransmitters from caged precursors at synaptic regions in the extracellular space is greatly hampered at irradiation wavelengths in the near-UV, close to the wavelength of maximum absorption of the caged precursor, because of inner-filtering by strong absorption of light in the cage solution between the objective and cell. For this reason two-photon excitation is commonly used for photolysis, particularly at multiple points distributed over large fields; or, with near-UV, if combined with local perfusion of the cage. These methods each have problems: the small cross-sections of common cages with two-photon excitation require high cage concentrations and light intensities near the phototoxic limit, while local perfusion gives non-uniform cage concentrations over the field of view. Single-photon photolysis at 405 nm, although less efficient than at 330-350 nm, with present cages is more efficient than two-photon photolysis. The reduced light absorption in the bulk cage solution permits efficient wide-field uncaging at non-toxic intensities with uniform cage concentration. Full photolysis of MNI-glutamate with 100 micros pulses required intensities of 2 mW microm(-2) at the preparation, shown to be non-toxic with repeated exposures. Light scattering at 405 nm was estimated as 50% at 18 microm depth in 21-day rat cerebellum. Methods are described for: (1) varying the laser spot size; (2) photolysis calibration in the microscope with the caged fluorophore NPE-HPTS over the wavelength range 347-405 nm; and (3) determining the point-spread function of excitation. Furthermore, DM-Nitrophen photolysis at 405 nm was efficient for intracellular investigations of Ca2+-dependent processes.

Correlating Species and Spectral Diversity using Remote Sensing in Successional Fields in Virginia

NASA Astrophysics Data System (ADS)

Aneece, I.; Epstein, H. E.

2015-12-01

Conserving biodiversity can help preserve ecosystem properties and function. As the increasing prevalence of invasive plant species threatens biodiversity, advances in remote sensing technology can help monitor invasive species and their effects on ecosystems and plant communities. To assess whether we could study the effects of invasive species on biodiversity using remote sensing, we asked whether species diversity was positively correlated with spectral diversity, and whether correlations differed among spectral regions along the visible and near-infrared range. To answer these questions, we established community plots in secondary successional fields at the Blandy Experimental Farm in northern Virginia and collected vegetation surveys and ground-level hyperspectral data from 350 to 1025 nm wavelengths. Pearson correlation analysis revealed a positive correlation between spectral diversity and species diversity in the visible ranges of 350-499 nm (Pearson correlation=0.69, p=0.01), 500-589 nm (Pearson=0.64, p=0.03), and 590-674 nm (Pearson=0.70, p=0.01), slight positive correlation in the red edge range of 675-754 nm (Pearson=0.56, p=0.06), and no correlation in the near-infrared ranges of 755-924 nm (Pearson=-0.06, p=0.85) and 925-1025 nm (Pearson=0.30, p=0.34). These differences in correlations across spectral regions may be due to the elements that contribute to signatures in those regions and spectral data transformation methods. To investigate the role of pigment variability in these correlations, we estimated chlorophyll, carotenoid, and anthocyanin concentrations of five dominant species in the plots using vegetation indices. Although interspecific variability in pigment levels exceeded intraspecific variability, chlorophyll (F value=118) was more varied within species than carotenoids (F=322) and anthocyanins (F=126), perhaps contributing to the lack of correlation between species diversity and spectral diversity in the red edge region. Interspecific differences in pigment levels, however, make it possible to differentiate species remotely.

Development of a laser induced breakdown spectrometer for detection of toxic elements in cosmetic products

NASA Astrophysics Data System (ADS)

Maganda, Yasin Wandhami

In this research work we developed a highly sensitive analytical Laser Induced Breakdown Spectrometer to detect toxic elements in commercially available cosmetic products. These products are frequently used by many all over the world, therefore there is an increasing demand to determine concentration levels of toxic elements present in them because they cause dangerous diseases and most of them are highly carcinogenic and life threatening. Laser Induced Breakdown Spectroscopy (LIBS) was applied for spectroscopic analysis of cosmetic products such as tooth paste, synthetic hair dye, kohl eyeliners and talcum powder samples. These samples were purchased from the local market within the kingdom of Saudi Arabia. The LIBS method is based on spectroscopic analysis of plasma resulting from the interaction of a high power pulsed laser radiations with a sample medium. In order to improve the sensitivity of the spectrometer, the dependence of the LIBS signal intensity and plasma parameters such as temperature (T) and electron density (ne) on gate/time delay, laser fluence and wavelength of the excitation source for plasma generated under ambient conditions were studied. During this work Nd: YAG lasers having 266nm, 532 nm and 1064 nm wavelengths operating in Q-switch mode were used as the excitation sources in combination with a spectrograph having a gated ICCD camera. Boltzmann plots and stark broadening for the recorded spectral lines were used to estimate the plasma temperature and electron density respectively. Temporal evolution of the plasma temperature and electron density showed a t-2 dependence. On the other hand plasma temperature and electron density increased with increase in laser fluence but leveled off at higher fluencies. It is worth noting that in both cases 266 nm and 1064 nm excitation wavelengths consistently had the highest and lowest values respectively. Therefore a 266 nm wavelength Nd: YAG laser excitation source was selected to develop a highly sensitive Laser Induced Breakdown spectrometer to detect and quantify the fluoride (F), lead (Pb) and chromium (Cr) content in commercially available toothpaste, synthetic hair dye, kohl eyeliners and talcum powder samples. The experimental parameters such as gate/ delays and laser fluencies were optimized to achieve an optically thin and in local thermodynamic equilibrium plasma (L.T.E) which improved the limit of detection of our spectrometer. The choice of the parameters was validated using the Mcwhirter criterion. For fluoride detection in the toothpaste samples, a strong atomic transition line of fluorine at 731.102 nm was used as the marker line. The LIBS system was able to detect fluoride concentration levels in the range of 1300 - 1750 ppm with a detection limit of 156ppm.In the synthetic hair dye, chromium was detected using a strong atomic transition of chromium (Cr) at a wavelength 427.5 nm as the spectral marker line and the spectrometer with a detection limit of 1.2 ppm was able to detect chromium concentration levels in the range of 5-11 ppm. These results achieved with our LIBS system were compared with those obtained using a standard detection method such as ICP-MS. The results obtained are in excellent agreement with ICP-MS. Lead (Pb) and Chromium (Cr) in kohl were detected using atomic transitions at wavelengths of 405.7 nm and 425.4 nm respectively as the spectral marker lines. The system was calibrated for these toxic metals and it was able to detect Lead and Chromium in the range of 5-14 ppm and 4-9 ppm with detection limits of 1ppm and 2 ppm respectively. The LIBS results were compared with those obtained using ICP-MS and were in good agreement yielding a relative accuracy in the range 0.05-0.3 which is acceptable. Lead (Pb) and Chromium (Cr) levels in talcum powder samples were detected and quantified using strong transitions at wavelengths of 405.7 nm and 425.4 nm respectively. The LIBS system detected lead and chromium in the range of 15-17 ppm and 23-29 ppm with limits of detection of 1.96 ppm and 1.72 ppm respectively. The concentration levels of fluoride, lead and chromium detected using our LIBS system exceeded the permissible limits set by the Environmental agency and other regulatory organization and hence frequent use of such cosmetic products can be hazardous to human health. The LIBS spectrometer developed through this research work can be applied for analysis of many other samples like pharmaceutical, polymers, iron, volcanic eruption and geological samples for mineral quantification.

Study of the pulse characteristics of semiconductor lasers with a broadened waveguide at low temperatures (110–120 K)

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

Veselov, D. A.; Shashkin, I. S.; Bobretsova, Yu. K.

2016-10-15

Pulse-pumped MOVPE-fabricated (metal-organic vapor-phase epitaxy) semiconductor lasers emitting in the spectral ranges 1000–1100 and 1400–1600 nm at temperatures of 110–120 K are studied. It is found that cooling the lasers for both spectral ranges to low temperature results in their light–current curves approaching linearity, and an optical power of, respectively, 110 and 20 W can be attained. The low-temperature effect is reduced for lasers emitting in the spectral range 1400–1600 nm. The processes affecting a rise in the internal optical loss in semiconductor lasers are considered. It is shown that an increase in the carrier concentration in the waveguide ofmore » a laser structure greatly depends on temperature and is determined by the noninstantaneous capture (capture rate) of carriers from the waveguide into the active region. It is demonstrated that, upon lowering the temperature to 115K, the concentration of electrons and holes in the waveguide becomes lower, which leads to a significant decrease in the internal optical loss and to an increase in the output optical power of the semiconductor laser.« less

Fluorescence chemodosimeter for dopamine based on the inner filter effect of the in situ generation of silver nanoparticles and fluorescent dye

NASA Astrophysics Data System (ADS)

Uppa, Yuwapon; Ngamdee, Kessarin; Promarak, Vinich; Ngeontae, Wittaya

2018-07-01

A new strategy for the sensitive and selective detection of dopamine (DA) was proposed. The chemodosimeter design was based on the measurement of the fluorescent quenching of fluorescein dye caused by the in situ generation of silver nanoparticles (AgNPs). The AgNPs can be simply generated by a reaction between DA and Ag+ in the presence of polymethacrylic acid (PMAA). In addition, the generated AgNPs possess the maximum surface plasmon resonance (SPR) at 440 nm and an increase in the SPR intensity with an increasing DA concentration. Basically, fluorescein dye can emit the fluorescent intensity maximum at 513 nm with excitation at 487 nm. Thus, fluorescent quenching was achieved due to an inner filter effect from the overlap between the excitation spectrum of the fluorescein dye and the SPR spectrum of the generated AgNPs. The degree of fluorescent quenching linearly depends on the number of generated AgNPs that can be directly related to the concentration of DA. The proposed chemodosimeter can be used to detect DA in a working linear concentration range of 1.0-5.0 μM at a detection limit of 10.6 nM. This chemodosimeter was successfully applied to determine DA in a real urine sample and a dopamine injection formulation with satisfactory results.

A Preliminary Assessment of Silver Nanoparticle Inhibition of Monkeypox Virus Plaque Formation

NASA Astrophysics Data System (ADS)

Rogers, James V.; Parkinson, Christopher V.; Choi, Young W.; Speshock, Janice L.; Hussain, Saber M.

2008-04-01

The use of nanotechnology and nanomaterials in medical research is growing. Silver-containing nanoparticles have previously demonstrated antimicrobial efficacy against bacteria and viral particles. This preliminary study utilized an in vitro approach to evaluate the ability of silver-based nanoparticles to inhibit infectivity of the biological select agent, monkeypox virus (MPV). Nanoparticles (10 80 nm, with or without polysaccharide coating), or silver nitrate (AgNO3) at concentrations of 100, 50, 25, and 12.5 μg/mL were evaluated for efficacy using a plaque reduction assay. Both Ag-PS-25 (polysaccharide-coated, 25 nm) and Ag-NP-55 (non-coated, 55 nm) exhibited a significant ( P ≤ 0.05) dose-dependent effect of test compound concentration on the mean number of plaque-forming units (PFU). All concentrations of silver nitrate (except 100 μg/mL) and Ag-PS-10 promoted significant ( P ≤ 0.05) decreases in the number of observed PFU compared to untreated controls. Some nanoparticle treatments led to increased MPV PFU ranging from 1.04- to 1.8-fold above controls. No cytotoxicity (Vero cell monolayer sloughing) was caused by any test compound, except 100 μg/mL AgNO3. These results demonstrate that silver-based nanoparticles of approximately 10 nm inhibit MPV infection in vitro, supporting their potential use as an anti-viral therapeutic.

Relationship between different size classes of particulate matter and meteorology in three European cities.

PubMed

de Hartog, Jeroen J; Hoek, Gerard; Mirme, Aadu; Tuch, Thomas; Kos, Gerard P A; ten Brink, Harry M; Brunekreef, Bert; Cyrys, Josef; Heinrich, Joachim; Pitz, Mike; Lanki, Timo; Vallius, Marko; Pekkanen, Juha; Kreyling, Wolfgang G

2005-04-01

Evidence on the correlation between particle mass and (ultrafine) particle number concentrations is limited. Winter- and spring-time measurements of urban background air pollution were performed in Amsterdam (The Netherlands), Erfurt (Germany) and Helsinki (Finland), within the framework of the EU funded ULTRA study. Daily average concentrations of ambient particulate matter with a 50% cut off of 2.5 microm (PM2.5), total particle number concentrations and particle number concentrations in different size classes were collected at fixed monitoring sites. The aim of this paper is to assess differences in particle concentrations in several size classes across cities, the correlation between different particle fractions and to assess the differential impact of meteorological factors on their concentrations. The medians of ultrafine particle number concentrations were similar across the three cities (range 15.1 x 10(3)-18.3 x 10(3) counts cm(-3)). Within the ultrafine particle fraction, the sub fraction (10-30 nm) made a higher contribution to particle number concentrations in Erfurt than in Helsinki and Amsterdam. Larger differences across the cities were found for PM2.5(range 11-17 microg m(-3)). PM2.5 and ultrafine particle concentrations were weakly (Amsterdam, Helsinki) to moderately (Erfurt) correlated. The inconsistent correlation for PM2.5 and ultrafine particle concentrations between the three cities was partly explained by the larger impact of more local sources from the city on ultrafine particle concentrations than on PM2.5, suggesting that the upwind or downwind location of the measuring site in regard to potential particle sources has to be considered. Also, relationship with wind direction and meteorological data differed, suggesting that particle number and particle mass are two separate indicators of airborne particulate matter. Both decreased with increasing wind speed, but ultrafine particle number counts consistently decreased with increasing relative humidity, whereas PM2.5 increased with increasing barometric pressure. Within the ultrafine particle mode, nucleation mode (10-30 nm) and Aitken mode (30-100 nm) had distinctly different relationships with accumulation mode particles and weather conditions. Since the composition of these particle fractions also differs, it is of interest to test in future epidemiological studies whether they have different health effects.

Perinatal Consumption of Thiamine-Fortified Fish Sauce in Rural Cambodia: A Randomized Clinical Trial.

PubMed

Whitfield, Kyly C; Karakochuk, Crystal D; Kroeun, Hou; Hampel, Daniela; Sokhoing, Ly; Chan, Benny B; Borath, Mam; Sophonneary, Prak; McLean, Judy; Talukder, Aminuzzaman; Lynd, Larry D; Li-Chan, Eunice C Y; Kitts, David D; Allen, Lindsay H; Green, Timothy J

2016-10-03

Infantile beriberi, a potentially fatal disease caused by thiamine deficiency, remains a public health concern in Cambodia and regions where thiamine-poor white rice is a staple food. Low maternal thiamine intake reduces breast milk thiamine concentrations, placing breastfed infants at risk of beriberi. To determine if consumption of thiamine-fortified fish sauce yields higher erythrocyte thiamine diphosphate concentrations (eTDP) among lactating women and newborn infants and higher breast milk thiamine concentrations compared with a control sauce. In this double-blind randomized clinical trial, 90 pregnant women were recruited in the Prey Veng province, Cambodia. The study took place between October 2014 and April 2015. Women were randomized to 1 of 3 groups (n = 30) for ad libitum fish sauce consumption for 6 months: control (no thiamine), low-concentration (2 g/L), or high-concentration (8 g/L) fish sauce. Maternal eTDP was assessed at baseline (October 2014) and endline (April 2015). Secondary outcomes, breast milk thiamine concentration and infant eTDP, were measured at endline. Women's mean (SD) age and gestational stage were 26 (5) years and 23 (7) weeks, respectively. April 2015 eTDP was measured among 28 women (93%), 29 women (97%), and 23 women (77%) in the control, low-concentration, and high-concentration groups, respectively. In modified intent-to-treat analysis, mean baseline-adjusted endline eTDP was higher among women in the low-concentration (282nM; 95% CI, 235nM to 310nM) and high-concentration (254nM; 95% CI, 225nM to 284nM) groups compared with the control group (193nM; 95% CI, 164nM to 222M; P < .05); low-concentration and high-concentration groups did not differ (P = .19). Breast milk total thiamine concentrations were 14.4 μg/dL for the control group (95% CI, 12.3 μg/dL to 16.5 μg/dL) (to convert to nanomoles per liter, multiply by 29.6); 20.7 μg/dL for the low-concentration group (95% CI, 18.6 μg/dL to 22.7 μg/dL ); and 17.7 μg/dL for the high-concentration group (95% CI, 15.6 μg/dL to 19.9 μg/dL). Mean (SD) infant age at endline was 16 (8) weeks for the control group, 17 (7) weeks for the low-concentration group, and 14 (8) for the high-concentration group. Infant eTDP was higher among those in the high-concentration group (257nM; 95% CI, 222nM to 291nM; P < .05) compared with the low-concentration (212nM; 95% CI, 181nM to 244nM) and control (187nM; 95% CI, 155nM to 218nM) groups. Compared with women in the control group, women who consumed thiamine-fortified fish sauce through pregnancy and early lactation had higher eTDP and breast milk thiamine concentrations and their infants had higher eTDP, which was more pronounced in the high group. Thiamine-fortified fish sauce has the potential to prevent infantile beriberi in this population. Clinicaltrials.gov Identifier: NCT02221063.

Refractive index of dark-adapted bacteriorhodopsin and tris(hydroxymethyl)aminomethane buffer between 390 and 880 nm.

PubMed

Heiner, Zsuzsanna; Osvay, Károly

2009-08-10

The refractivity of wild-type bacteriorhodopsin (bR(WT)) suspended in tris(hydroxymethyl)aminomethane (TRIS) buffer has been measured in the spectral range of 390-840 nm by the method of angle of minimal deviation with the use of a hollow glass prism. The refractive indices of pure bR(WT) as well as of TRIS buffer have been determined from the concentration dependent refraction values. Sellmeier-type dispersion equations have been fitted for both the TRIS buffer and pure bR(WT).

Measuring lanthanide concentrations in molten salt using laser-induced breakdown spectroscopy (LIBS).

PubMed

Weisberg, Arel; Lakis, Rollin E; Simpson, Michael F; Horowitz, Leo; Craparo, Joseph

2014-01-01

The versatility of laser-induced breakdown spectroscopy (LIBS) as an analytical method for high-temperature applications was demonstrated through measurement of the concentrations of the lanthanide elements europium (Eu) and praseodymium (Pr) in molten eutectic lithium chloride-potassium chloride (LiCl-KCl) salts at a temperature of 500 °C. Laser pulses (1064 nm, 7 ns, 120 mJ/pulse) were focused on the top surface of the molten salt samples in a laboratory furnace under an argon atmosphere, and the resulting LIBS signals were collected using a broadband Echelle-type spectrometer. Partial least squares (PLS) regression using leave-one-sample-out cross-validation was used to quantify the concentrations of Eu and Pr in the samples. The root mean square error of prediction (RMSEP) for Eu was 0.13% (absolute) over a concentration range of 0-3.01%, and for Pr was 0.13% (absolute) over a concentration range of 0-1.04%.

Interference of single walled carbon nanotubes (SWCNT) in the measurement of lipid peroxidation in aquatic organisms through TBARS assay.

PubMed

Monserrat, J M; Seixas, A L R; Ferreira-Cravo, M; Bürguer-Mendonça, M; Garcia, S C; Kaufmann, C G; Ventura-Lima, J

2017-06-01

Nanomaterials (NM) exhibit unique properties due their size and relative area, but the mechanisms and effects in the living organisms are yet to be unfold in their totality. Potential toxicity mechanisms concerning NM as carbon nanotubes include oxidative stress generation. Several fluorimetric and colorimetric methods have been systematically used to measure NM toxicity, and controversial results have been reported. One of the problems can be related to the interference effects induced by NM, leading to artifacts that can lead to misleading conclusions. In present study, it was performed in vitro assays with two aquatic species: the zebrafish Danio rerio and the polychaete Laeonereis acuta to evaluate the potential interference capacity of single-wall carbon nanotubes (SWCNT) in a fluorometric method (TBARS assay) to measure lipid peroxidation. Obtained results indicated that gills and brain of zebrafish presented a lowered fluorescence only at extremely high concentrations (50 and 500mg/L). Determinations in anterior, middle, and posterior body regions of L. acuta showed a quite different pattern: high fluorescence at low SWCNT concentrations (0.5mg/L) and lowering at the highest (500mg/L). To eliminate matrix effect of biological samples, tests employing the standard for TBARS assay, 1,3,3-tetramethoxipropane, were run and the results showed again higher fluorescence values at low concentrations (0.5-5mg SWCNT/L), a technique artifact that could lead to misleading conclusions since higher fluorescence values implicate higher TBARS concentration, implying oxidative stress. Using the colorimetric FOX assay with cumene hydroperoxide as standard presented remarkable better results since no artifacts were observed in the same SWCNT concentration range that employed with the TBARS technique. Copyright © 2017 Elsevier Inc. All rights reserved.

An In Situ Method for Sizing Insoluble Residues in Precipitation and Other Aqueous Samples

PubMed Central

Axson, Jessica L.; Creamean, Jessie M.; Bondy, Amy L.; Capracotta, Sonja S.; Warner, Katy Y.; Ault, Andrew P.

2015-01-01

Particles are frequently incorporated into clouds or precipitation, influencing climate by acting as cloud condensation or ice nuclei, taking up coatings during cloud processing, and removing species through wet deposition. Many of these particles, particularly ice nuclei, can remain suspended within cloud droplets/crystals as insoluble residues. While previous studies have measured the soluble or bulk mass of species within clouds and precipitation, no studies to date have determined the number concentration and size distribution of insoluble residues in precipitation or cloud water using in situ methods. Herein, for the first time we demonstrate that Nanoparticle Tracking Analysis (NTA) is a powerful in situ method for determining the total number concentration, number size distribution, and surface area distribution of insoluble residues in precipitation, both of rain and melted snow. The method uses 500 μL or less of liquid sample and does not require sample modification. Number concentrations for the insoluble residues in aqueous precipitation samples ranged from 2.0–3.0(±0.3)×108 particles cm−3, while surface area ranged from 1.8(±0.7)–3.2(±1.0)×107 μm2 cm−3. Number size distributions peaked between 133–150 nm, with both single and multi-modal character, while surface area distributions peaked between 173–270 nm. Comparison with electron microscopy of particles up to 10 μm show that, by number, > 97% residues are <1 μm in diameter, the upper limit of the NTA. The range of concentration and distribution properties indicates that insoluble residue properties vary with ambient aerosol concentrations, cloud microphysics, and meteorological dynamics. NTA has great potential for studying the role that insoluble residues play in critical atmospheric processes. PMID:25705069

Application of response surface methodology (RSM) to the optimization of a post-column luminol chemiluminescence analysis of silyl peroxides.

PubMed

Baj, Stefan; Słupska, Roksana; Krawczyk, Tomasz

2013-01-15

The possibility of the utilization of chemiluminescence post-column luminol oxidation (CL) in a HPLC system for silyl peroxides analysis has been investigated. The conditions of HPLC separation for 12 silyl peroxides, representing bissilyl and alkyl-silyl peroxides, as well as their potential impurities, were established. Optimal chemiluminescent post-column reaction conditions were found using central composite design (CCD) and response surface methodology (RSM). The interaction effects of four of the most important operating variables - the concentrations of luminol, hemin, sodium hydroxide and the post-column solution flow rate - on the light intensity were evaluated. The optimized conditions for analysis were the same for bissilyl and alkyl-silyl peroxides for the base concentration (0.03 M), the luminol concentration (0.4 g L(-1)) and the hemin concentration (0.3 g L(-1)). The only differences occurred in a reagent flow rate (for bissilyl peroxide -0.3 mL min(-1) and for alkyl-silyl peroxides -0.9 mL min(-1)). Under optimal conditions, the detection limits were in the 0.07-0.16 nM range for bissilyl, and 0.53-1.01 for alkyl-silyl peroxides. The calibration curves were linear in the 0.25-3 nM range for bissilyl and the 2.5-25 range for alkyl-silyl peroxides. Intra-day and inter-day precision was lower than 5.5% for each tested concentration level. A mechanism of luminol oxidation by silyl peroxides involving a hydrolysis step with the formation of hydrogen peroxide or hydroperoxide was proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

Cloud condensation nuclei in pristine tropical rainforest air of Amazonia: size-resolved measurements and modeling of atmospheric aerosol composition and CCN activity

NASA Astrophysics Data System (ADS)

Gunthe, S. S.; King, S. M.; Rose, D.; Chen, Q.; Roldin, P.; Farmer, D. K.; Jimenez, J. L.; Artaxo, P.; Andreae, M. O.; Martin, S. T.; Pöschl, U.

2009-10-01

Atmospheric aerosol particles serving as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. We have measured and characterized CCN at water vapor supersaturations in the range of S=0.10-0.82% in pristine tropical rainforest air during the AMAZE-08 campaign in central Amazonia. The effective hygroscopicity parameters describing the influence of chemical composition on the CCN activity of aerosol particles varied in the range of κ≍0.1-0.4 (0.16±0.06 arithmetic mean and standard deviation). The overall median value of κ≍0.15 was by a factor of two lower than the values typically observed for continental aerosols in other regions of the world. Aitken mode particles were less hygroscopic than accumulation mode particles (κ≍0.1 at D≍50 nm; κ≍0.2 at D≍200 nm), which is in agreement with earlier hygroscopicity tandem differential mobility analyzer (H-TDMA) studies. The CCN measurement results are consistent with aerosol mass spectrometry (AMS) data, showing that the organic mass fraction (forg) was on average as high as ~90% in the Aitken mode (D≤100 nm) and decreased with increasing particle diameter in the accumulation mode (~80% at D≍200 nm). The κ values exhibited a negative linear correlation with forg (R2=0.81), and extrapolation yielded the following effective hygroscopicity parameters for organic and inorganic particle components: κorg≍0.1 which can be regarded as the effective hygroscopicity of biogenic secondary organic aerosol (SOA) and κinorg≍0.6 which is characteristic for ammonium sulfate and related salts. Both the size dependence and the temporal variability of effective particle hygroscopicity could be parameterized as a function of AMS-based organic and inorganic mass fractions (κp=κorg×forg +κinorg×finorg). The CCN number concentrations predicted with κp were in fair agreement with the measurement results (~20% average deviation). The median CCN number concentrations at S=0.1-0.82% ranged from NCCN,0.10≍35 cm-3 to NCCN,0.82≍160 cm-3, the median concentration of aerosol particles larger than 30 nm was NCN,30≍200 cm-3, and the corresponding integral CCN efficiencies were in the range of NCCN,0.10/NCN,30≍0.1 to NCCN,0.82/NCN,30≍0.8. Although the number concentrations and hygroscopicity parameters were much lower in pristine rainforest air, the integral CCN efficiencies observed were similar to those in highly polluted megacity air. Moreover, model calculations of NCCN,S assuming an approximate global average value of κ≍0.3 for continental aerosols led to systematic overpredictions, but the average deviations exceeded ~50% only at low water vapor supersaturation (0.1%) and low particle number concentrations (≤100 cm-3). Model calculations assuming a constant aerosol size distribution led to higher average deviations at all investigated levels of supersaturation: ~60% for the campaign average distribution and ~1600% for a generic remote continental size distribution. These findings confirm earlier studies suggesting that aerosol particle number and size are the major predictors for the variability of the CCN concentration in continental boundary layer air, followed by particle composition and hygroscopicity as relatively minor modulators. Depending on the required and applicable level of detail, the information and parameterizations presented in this paper should enable efficient description of the CCN properties of pristine tropical rainforest aerosols of Amazonia in detailed process models as well as in large-scale atmospheric and climate models.

Isokinetic peak torque and flexibility changes of the hamstring muscles after eccentric training: Trained versus untrained subjects.

PubMed

Abdel-Aziem, Amr Almaz; Soliman, Elsadat Saad; Abdelraouf, Osama Ragaa

2018-05-23

The aim of this study was to examine the effect of eccentric isotonic training on hamstring flexibility and eccentric and concentric isokinetic peak torque in trained and untrained subjects. Sixty healthy subjects (mean age: 21.66 ± 2.64) were divided into three equal groups, each with 20 voluntary participants. Two experimental groups (untrained and trained groups) participated in a hamstring eccentric isotonic strengthening program (five days/week) for a six-week period and one control group that was not involved in the training program. The passive knee extension range of motion and hamstring eccentric and concentric isokinetic peak torque were measured at angular velocities 60° and 120°/s for all groups before and after the training period. Two-way analysis of variance showed that there was a significant increase in the hamstring flexibility of the untrained and trained groups (25.65 ± 6.32°, 26.55 ± 5.99°, respectively), (p < 0.05) without a significant increase in the control group (31.55 ± 5.84°), (p > 0.05). Moreover, there was a significant increase in eccentric isokinetic peak torque of both the untrained and trained groups (127.25 ± 22.60Nm, 139.65 ± 19.15Nm, 125.40 ± 21.61Nm, 130.90 ± 18.71Nm, respectively), (p < 0.05) without a significant increase in the control group (109.15 ± 20.89Nm, 105.70 ± 21.31Nm, respectively), (p > 0.05) at both angular velocities. On the other hand, there was no significant increase in the concentric isokinetic peak torque of the three groups (92.50 ± 20.50Nm, 79.05 ± 18.95Nm, 92.20 ± 21.96Nm, 79.85 ± 18.97Nm, 100.45 ± 25.78Nm, 83.40 ± 23.73Nm, respectively), (p > 0.05) at both angular velocities. The change scores in the hamstring flexibility (06.25 ± 1.86°) and eccentric peak torque of the untrained group (16.60 ± 4.81Nm, 17.45 ± 5.40Nm, respectively) were significantly higher (p < 0.05) than those of the trained group (03.40 ± 1.14°, 9.90 ± 5.14Nm, 9.80 ± 7.57Nm, respectively), and the control group (00.90 ± 2.10°, 0.60 ± 2.93Nm, 1.40 ± 3.53Nm, respectively), at both angular velocities. Meanwhile, the change scores of the concentric peak torques of the three groups (1.15 ± 1.50Nm, -0.15 ± 2.16Nm, 1.35 ± 1.63Nm, 0.20 ± 2.95Nm, 0.60 ± 2.28Nm, -0.30 ± 2.25Nm) were statistically insignificant (p > 0.05). After a six-week period of eccentric isotonic training, the hamstring eccentric peak torque and flexibility of trained and untrained groups improved without changes in the concentric peak torque. Moreover, the improvement of untrained subjects was higher than trained subjects. These findings may be helpful in designing the hamstring rehabilitation program. Copyright © 2018 Turkish Association of Orthopaedics and Traumatology. Production and hosting by Elsevier B.V. All rights reserved.

An external template-free route to uniform semiconducting hollow mesospheres and their use in photocatalysis

NASA Astrophysics Data System (ADS)

Yang, Di; Wang, Mengye; Zou, Bin; Zhang, Gu Ling; Lin, Zhiqun

2015-07-01

Solid amorphous TiO2 mesospheres were synthesized by controlled hydrolysis of Ti-containing precursors. Subsequently, solid TiO2 mesospheres were exploited as scaffolds and subjected to a one-step external template-free hydrothermal treatment, yielding intriguing hollow anatase TiO2 mesospheres. The synthetic protocol was optimized by investigating the effect of buffer reagents and fluoride ions on the formation of hollow TiO2 spheres. The diameter of hollow mesospheres, ranging from 308 to 760 nm, can be readily tailored by varying the precursor concentration. The average thickness of a shell composed of TiO2 nanocrystals was approximately 40 nm with a mean crystal size of 12.4-20.0 nm. Such hollow TiO2 mesospheres possessed a large surface area and were employed in photocatalytic degradation of methylene blue under UV irradiation. Interestingly, the synthetic conditions were found to exert a significant influence on the photocatalytic ability of hollow TiO2 mesospheres. The correlation between the degradation ability of hollow TiO2 mesospheres and the precursor concentration as well as the hydrothermal time was scrutinized. The optimal photocatalytic performance of hollow TiO2 mesospheres was identified.Solid amorphous TiO2 mesospheres were synthesized by controlled hydrolysis of Ti-containing precursors. Subsequently, solid TiO2 mesospheres were exploited as scaffolds and subjected to a one-step external template-free hydrothermal treatment, yielding intriguing hollow anatase TiO2 mesospheres. The synthetic protocol was optimized by investigating the effect of buffer reagents and fluoride ions on the formation of hollow TiO2 spheres. The diameter of hollow mesospheres, ranging from 308 to 760 nm, can be readily tailored by varying the precursor concentration. The average thickness of a shell composed of TiO2 nanocrystals was approximately 40 nm with a mean crystal size of 12.4-20.0 nm. Such hollow TiO2 mesospheres possessed a large surface area and were employed in photocatalytic degradation of methylene blue under UV irradiation. Interestingly, the synthetic conditions were found to exert a significant influence on the photocatalytic ability of hollow TiO2 mesospheres. The correlation between the degradation ability of hollow TiO2 mesospheres and the precursor concentration as well as the hydrothermal time was scrutinized. The optimal photocatalytic performance of hollow TiO2 mesospheres was identified. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02685g

Tellurium-nanowire-coated glassy carbon electrodes for selective and sensitive detection of dopamine.

PubMed

Tsai, Hsiang-Yu; Lin, Zong-Hong; Chang, Huan-Tsung

2012-05-15

Tellurium-nanowire-coated glassy carbon electrodes (TNGCEs) have been fabricated and employed for selective and sensitive detection of dopamine (DA). TNGCEs were prepared by direct deposition of tellurium nanowires, 600 ± 150 nm in length and 16 ± 3 nm in diameter, onto glassy carbon electrodes, which were further coated with Nafion to improve their selectivity and stability. Compared to the GCE, the TNGCE is more electroactive (by approximately 1.9-fold) for DA, and its selectivity toward DA over ascorbic acid (AA) and uric acid (UA) is also greater. By applying differential pulse voltammetry, at a signal-to-noise ratio of 3, the TNGCE provides a limit of detection of 1 nM for DA in the presence of 0.5mM AA and UA. Linearity (R(2)=0.9955) of the oxidation current at 0.19 V against the concentration of DA is found over the range 5 nM-1 μM. TNGCEs have been applied to determine the concentration of dopamine to be 0.59 ± 0.07 μM in PC12 cells. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis Structural and Optical Properties Of (Co, Al) co-doped ZnO Nano Particles

NASA Astrophysics Data System (ADS)

Swapna, P.; Venkatramana Reddy, S.

2018-02-01

We prepared (Co, Al) co-doped ZnO nanostructures using the method chemical co-precipitation successfully, at room temperature using PEG (Poly ethylene glycol) as stabilizing agent. Samples are prepared with different concentrations by keeping aluminium at 5 mol percent constant and varying the concentration of cobalt from 1 to 5 mol percent. After the preparation all the samples are carefully subjected to characterizations such as XRD, SEM with EDS, TEM, PL and UV-VIS-NIR. XRD pattern shows that all the samples possess hexagonal wurtzite crystal structure having no secondary phases pertaining to Al or cobalt, which shows successful dissolution of the dopents. TEM results shows the accurate size of particles and is confirmed the XRD data. SEM images of all the samples shows that particles are in nearly spherical shape, EDS spectrum reveals that incorporation of cobalt and aluminum in host lattice. PL spectrum shows that all the samples containing two prominent peaks centered at 420 nm and 446 nm. UV-VIS-NIR spectra has shown three absorptions peaks in the range of wavelength 550 nm to 700 nm, which are ascribed as typical d-d transitions of cobalt ions.

Photothermal evaluation of the influence of nicotine, antitumor drugs, and radiation on cellular absorbing structures

NASA Astrophysics Data System (ADS)

Zharov, Vladimir P.; Galitovsky, Valentin; Chowdhury, Parimal; Chambers, Timothy

2004-07-01

This short review presents findings from a recent evaluation of the diagnostic capabilities of a new experimental design of the advanced photothermal (PT) imaging system; specifically, its performance in studying the impact of nicotine, a combination of antitumor drugs, and radiation on the absorbing structures of various cells. We used this imaging system to test our hypothesis that low doses of chemicals or drugs lead to changes in cell metabolism, that these changes are accompanied by the shrinking of cellular absorbing zones (e.g. organelles), and that these reactions cause increased local absorption. Conversely, high (toxic) doses may lead to swelling of organelles or release of chromophores into the intracellular space, causing decreased local absorption. In this study, we compared PT images and PT responses of the pancreatic exocrine tumor cell line AR42J resulting from exposure to various concentrations of nicotine versus those of control cells. We found that responses were almost proportional to the drug concentration in concentrations ranging from 1 nM-100 μM, reached saturation at a maximum of approximately 100 μM-1 mM, and then fell rapidly at concentrations ranging from 1-50 mM. We also examined the influence of antitumor drugs (vinblastine and paclitaxel) on KB3 carcinoma cells, with drug concentrations ranging from 10-10 nM to 10 nM. In this instance, exposure initially led to slight cell activation, which was then followed by decreased cellular PT response. Drug administration led to corresponding changes in the amplitude and spatial intracellular localization of PT responses, including bubble formation, as an indicator of local absorption level. Additionally, it was shown that, depending on cell type, x-ray radiation may produce effects similar to those resulting from exposure to drugs. Independent verification with a combined PT-fluorescence assay and conventional staining kits (trypan blue, Annexin V-propidium iodide [PI]) revealed that this new PT assay has the potential to detect different stages of environmental impact, including changes in cell metabolism and apoptotic- and toxic-related phenomena, at a concentration threshold sensitivity at least three orders of magnitude better than existing assays. This assay may also help optimize combined cancer therapies.

Hyperspectral Analysis of Soil Nitrogen, Carbon, Carbonate, and Organic Matter Using Regression Trees

PubMed Central

Gmur, Stephan; Vogt, Daniel; Zabowski, Darlene; Moskal, L. Monika

2012-01-01

The characterization of soil attributes using hyperspectral sensors has revealed patterns in soil spectra that are known to respond to mineral composition, organic matter, soil moisture and particle size distribution. Soil samples from different soil horizons of replicated soil series from sites located within Washington and Oregon were analyzed with the FieldSpec Spectroradiometer to measure their spectral signatures across the electromagnetic range of 400 to 1,000 nm. Similarity rankings of individual soil samples reveal differences between replicate series as well as samples within the same replicate series. Using classification and regression tree statistical methods, regression trees were fitted to each spectral response using concentrations of nitrogen, carbon, carbonate and organic matter as the response variables. Statistics resulting from fitted trees were: nitrogen R2 0.91 (p < 0.01) at 403, 470, 687, and 846 nm spectral band widths, carbonate R2 0.95 (p < 0.01) at 531 and 898 nm band widths, total carbon R2 0.93 (p < 0.01) at 400, 409, 441 and 907 nm band widths, and organic matter R2 0.98 (p < 0.01) at 300, 400, 441, 832 and 907 nm band widths. Use of the 400 to 1,000 nm electromagnetic range utilizing regression trees provided a powerful, rapid and inexpensive method for assessing nitrogen, carbon, carbonate and organic matter for upper soil horizons in a nondestructive method. PMID:23112620

Spectroscopic Characterization of Streptavidin Functionalized Quantum dots1

PubMed Central

Wu, Yang; Lopez, Gabriel P.; Sklar, Larry A.; Buranda, Tione

2007-01-01

The spectroscopic properties of quantum dots can be strongly influenced by the conditions of their synthesis. In this work we have characterized several spectroscopic properties of commercial, streptavidin functionalized quantum dots (QD525, lot#1005-0045 and QD585, Lot#0905-0031 from Invitrogen). This is the first step in the development of calibration beads, to be used in a generalizable quantification scheme of multiple fluorescent tags in flow cytometry or microscopy applications. We used light absorption, photoexcitation, and emission spectra, together with excited-state lifetime measurements to characterize their spectroscopic behavior, concentrating on the 400-500nm wavelength ranges that are important in biological applications. Our data show an anomalous dependence of emission spectrum, lifetimes, and quantum yield (QY) on excitation wavelength that is particularly pronounced in the QD525. For QD525, QY values ranged from 0.2 at 480nm excitation up to 0.4 at 450nm and down again to 0.15 at 350nm. For QD585, QY values were constant at 0.2 between 500nm and 400nm, but dropped to 0.1 at 350nm. We attribute the wavelength dependences to heterogeneity in size and surface defects in the QD525, consistent with characteristics previously described in the chemistry literature. The results are discussed in the context of bridging the gap between what is currently known in the physical chemistry literature of quantum dots, and the quantitative needs of assay development in biological applications. PMID:17368555

Epithelial cell biocompatibility of silica nanospheres for contrast-enhanced ultrasound molecular imaging

NASA Astrophysics Data System (ADS)

Chiriacò, Fernanda; Conversano, Francesco; Soloperto, Giulia; Casciaro, Ernesto; Ragusa, Andrea; Sbenaglia, Enzo Antonio; Dipaola, Lucia; Casciaro, Sergio

2013-07-01

Nanosized particles are receiving increasing attention as future contrast agents (CAs) for ultrasound (US) molecular imaging, possibly decorated on its surface with biological recognition agents for targeted delivery and deposition of therapeutics. In particular, silica nanospheres (SiNSs) have been demonstrated to be feasible in terms of contrast enhancement on conventional US systems. In this work, we evaluated the cytotoxicity of SiNSs on breast cancer (MCF-7) and HeLa (cervical cancer) cells employing NSs with sizes ranging from 160 to 330 nm and concentration range of 1.5-5 mg/mL. Cell viability was evaluated in terms of size, dose and time dependence, performing the MTT reduction assay with coated and uncoated SiNSs. Whereas uncoated SiNSs caused a variable significant decrease in cell viability on both cell lines mainly depending on size and exposure time, PEGylated SiNSs (SiNSs-PEG) exhibit a high level of biocompatibility. In fact, after 72-h incubation, viability of both cell types was above the cutoff value of 70 % at concentration up to 5 mg/mL. We also investigated the acoustical behavior of coated and uncoated SiNSs within conventional diagnostic US fields in order to determine a suitable configuration, in terms of particle size and concentration, for their employment as targetable CAs. Our results indicate that the employment of SiNSs with diameters around 240 nm assures the most effective contrast enhancement even at the lowest tested concentration, coupled with the possibility of targeting all tumor tissues, being the SiNSs still in a size range where reticuloendothelial system trapping effect is relatively low.

Evaluation of a coupled dispersion and aerosol process model against measurements near a major road

NASA Astrophysics Data System (ADS)

Pohjola, M. A.; Pirjola, L.; Karppinen, A.; Härkönen, J.; Ketzel, M.; Kukkonen, J.

2007-02-01

A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17-20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm-10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3-50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible at this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm-3 was shown to be in a disagreement with the measured particle size evolution, while the modelling runs with the concentration of condensable organic vapour of 109-1010 molecules cm-3 resulted in particle sizes that were closest to the measured values.

Boiling-induced formation of colloidal gold in black smoker hydrothermal fluids

USGS Publications Warehouse

Gartman, Amy; Hannington, Mark; Jamieson, John W.; Peterkin, Ben; Garbe-Schönberg, Dieter; Findlay, Alyssa J; Fuchs, Sebastian; Kwasnitschka, Tom

2017-01-01

Gold colloids occur in black smoker fluids from the Niua South hydrothermal vent field, Lau Basin (South Pacific Ocean), confirming the long-standing hypothesis that gold may undergo colloidal transport in hydrothermal fluids. Six black smoker vents, varying in temperature from 250 °C to 325 °C, were sampled; the 325 °C vent was boiling at the time of sampling and the 250 °C fluids were diffusely venting. Native gold particles ranging from <50 nm to 2 µm were identified in 4 of the fluid samples and were also observed to precipitate on the sampler during collection from the boiling vent. Total gold concentrations (dissolved and particulate) in the fluid samples range from 1.6 to 5.4 nM in the high-temperature, focused flow vents. Although the gold concentrations in the focused flow fluids are relatively high, they are lower than potential solubilities prior to boiling and indicate that precipitation was boiling induced, with sulfide lost upon boiling to exsolution and metal sulfide formation. Gold concentrations reach 26.7 nM in the 250 °C diffuse flow sample, and abundant native gold particles were also found in the fluids and associated sulfide chimney and are interpreted to be a product of colloid accumulation and growth following initial precipitation upon boiling. These results indicate that colloid-driven precipitation as a result of boiling, the persistence of colloids after boiling, and the accumulation of colloids in diffuse flow fluids are important mechanisms for the enrichment of gold in seafloor hydrothermal systems.

Realization of BP neural network modeling based on NOXof CFB boiler in DCS

NASA Astrophysics Data System (ADS)

Bai, Jianyun; Zhu, Zhujun; Wang, Qi; Ying, Jiang

2018-02-01

In the CFB boiler installed with SNCR denitrification system, the mass concentration of NO X is difficult to be predicted by the conventional mathematical model, and the step response mathematical model, obtained by using the step disturbance test of ammonia injection,is inaccurate. this paper presents two kinds of BP neural network model, according to the relationship between the generated mass concentration of NO X and the load, the ratio of air to coal without using the SNCR system, as well as the relationship between the tested mass concentration of NO X and the load, the ratio of air to coal and the amount of ammonia using the SNCR system. then itrealized the on-line prediction of the mass concentration of NO X and the remaining mass concentration of NO X after reductionreaction in DCS system. the practical results show that the average error per hour between generation and the prediction of the amount of NO X mass concentration is within 10 mg/Nm3,the reducing reaction of measured and predicted hourly average error is within 2 mg/Nm3, all in error range, which provides a more accurate model for solvingthe problem on NO X automatic control of SNCR system.

What goes on behind closed doors: physiological vs. pharmacological steroid hormone actions

PubMed Central

Simons, S. Stoney

2009-01-01

Summary Steroid hormone-activated receptor proteins are among the best understood class of factors for altering gene transcription in cells. Steroid receptors are of major importance in maintaining normal human physiology by responding to circulating concentrations of steroid in the nM range. Nonetheless, most studies of steroid receptor action have been conducted using the supra-physiological conditions of saturating concentrations (≥100 nM) of potent synthetic steroid agonists. Here we summarize the recent developments arising from experiments using two clinically relevant conditions: subsaturating concentrations of agonist (to mimic the circulating concentrations in mammals) and saturating concentrations of antagonists (which are employed in endocrine therapies to block the actions of endogenous steroids). These studies have revealed new facets of steroid hormone action that could not be uncovered by conventional experiments with saturating concentrations of agonist steroids, such as a plethora of factors/conditions for the differential control of gene expression by physiological levels of steroid, a rational approach for examining the gene-specific variations in partial agonist activity of antisteroids, and a dissociation of steroid potency and efficacy that implies the existence of separate, and possibly novel, mechanistic steps and cofactors. PMID:18623071

A fast integrated mobility spectrometer for rapid measurement of sub-micrometer aerosol size distribution, Part II: Experimental characterization

DOE PAGES

Wang, Jian; Pikridas, Michael; Pinterich, Tamara; ...

2017-06-08

A Fast Integrated Mobility Spectrometer (FIMS) with a wide dynamic size range has been developed for rapid aerosol size distribution measurements. The design and model evaluation of the FIMS are presented in the preceding paper (Paper I), and this paper focuses on the experimental characterization of the FIMS. Monodisperse aerosol with diameter ranging from 8 to 600 nm was generated using Differential Mobility Analyzer (DMA), and was measured by the FIMS in parallel with a Condensation Particle Counter (CPC). The mean particle diameter measured by the FIMS is in good agreement with the DMA centroid diameter. Comparison of the particlemore » concentrations measured by the FIMS and CPC indicates the FIMS detection efficiency is essentially 100% for particles with diameters of 8 nm or larger. For particles smaller than 20 nm or larger than 200 nm, FIMS transfer function and resolution can be well represented by the calculated ones based on simulated particle trajectories in the FIMS. For particles between 20 and 200 nm, the FIMS transfer function is boarder than the calculated, likely due to non-ideality of the electric field, including edge effects near the end of the electrode, which are not represented by the 2-D electric field used to simulate particle trajectories.« less

Synthesis of Water Dispersible Fluorescent Carbon Nanocrystals from Syzygium cumini Fruits for the Detection of Fe3+ Ion in Water and Biological Samples and Imaging of Fusarium avenaceum Cells.

PubMed

Bhamore, Jigna R; Jha, Sanjay; Singhal, Rakesh Kumar; Kailasa, Suresh Kumar

2017-01-01

In this work, water dispersible fluorescent carbon nanocrystals (NCs) were synthesized by a simple, green and low cost hydrothermal method using Syzygium cumini (jamun) as a carbon source at 180 °C for 6 h. The average size of carbon NCs was found to be 2.1 ± 0.5 nm and shown bright blue fluorescence when excited at 365 nm under UV lamp. The carbon NCs were characterized by spectroscopic (UV-visible and fluorescence, Fourier transform infrared and dynamic light scattering) and high resolution transmission electron microscopic techniques. The quantum yield of carbon NCs was found to be ~5.9 % at 438 nm emission wavelength when excited at 360 nm. It was noticed that none of the metal ions quenched the fluorescence intensity of carbon NCs at 438 nm except for Fe 3+ , indicating the formation of Fe 3+ ion-carbon NCs complexes. The linear range was observed in the concentration range of 0.01-100 μM with the corresponding detection limits of 0.001 μM, respectively. Furthermore, the carbon NCs were used as probes for imaging of fungal (Fusarium avenaceum) cells.

A fast integrated mobility spectrometer for rapid measurement of sub-micrometer aerosol size distribution, Part II: Experimental characterization

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

Wang, Jian; Pikridas, Michael; Pinterich, Tamara

A Fast Integrated Mobility Spectrometer (FIMS) with a wide dynamic size range has been developed for rapid aerosol size distribution measurements. The design and model evaluation of the FIMS are presented in the preceding paper (Paper I), and this paper focuses on the experimental characterization of the FIMS. Monodisperse aerosol with diameter ranging from 8 to 600 nm was generated using Differential Mobility Analyzer (DMA), and was measured by the FIMS in parallel with a Condensation Particle Counter (CPC). The mean particle diameter measured by the FIMS is in good agreement with the DMA centroid diameter. Comparison of the particlemore » concentrations measured by the FIMS and CPC indicates the FIMS detection efficiency is essentially 100% for particles with diameters of 8 nm or larger. For particles smaller than 20 nm or larger than 200 nm, FIMS transfer function and resolution can be well represented by the calculated ones based on simulated particle trajectories in the FIMS. For particles between 20 and 200 nm, the FIMS transfer function is boarder than the calculated, likely due to non-ideality of the electric field, including edge effects near the end of the electrode, which are not represented by the 2-D electric field used to simulate particle trajectories.« less

Determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture using high-performance liquid chromatographic-UV and spectrometric methods.

PubMed

Salem, Hesham

2010-01-01

Three methods were developed for simultaneous determination of metformin hydrochloride and glyburide in an antihyperglycemic binary mixture without previous separation. In the first method, a reversed-phase HPLC column with acetonitrile-water (60 + 40, v/v) mobile phase at 0.9 mL/min flow rate was used to separate both compounds, with UV detection at 254 nm. Linearity was obtained in the concentration range of 0.06--0.24 microg/mL for glyburide and 1.5-6.0 microg/mL for metformin hydrochloride. The second method depended on first- and second-derivative UV spectrometry with zero-crossing measurements. The first-derivative amplitude at 261 nm was selected for the assay of glyburide, and the second-derivative amplitude at 235 nm was selected for the assay of metformin hydrochloride. The third method depended on measuring the first derivative of the ratio-spectra at 241 nm for glyburide and 227 nm for metformin hydrochloride. For the second and third methods, Beer's law was obeyed in the range of 10-55 microg/mL for glyburide and 20-200 microg/mL for metformin. The proposed methods were extensively validated and applied for the analysis of some pharmaceutical formulations containing binary mixtures of the mentioned drugs.

New method for monitoring nitric oxide in vivo using microdialysis sampling and chemiluminescence reaction

NASA Astrophysics Data System (ADS)

Yao, Dachun; Evmiridis, Nick P.; Zhou, Yikai; Xu, Shunqing; Zhou, Huarong

2001-09-01

A new method employing a combination of micro dialysis sampling and chemiluminescence reaction was developed to monitor nitric oxide (NO) in vivo. A special probe was designed with an interference-free membrane to achieve a very high selectivity for NO. High sensitivity was achieved by optimizing the working system and improving the NO sampling time. This system was used in vivo to monitor blood and brain tissue in rats and rabbits. We have established that this system is sensitive enough to detect variations in NO production in difference physiological state. The system can detect NO in the linear range of 5nM-1(mu) M, with a detection limit of 1nM, and real NO concentrations in our experimental animals were found to be in the range of 1-5 nM or even less. Finally, the effects of body temperature, NO donors, Viagra, NO activators, NO cofactors, NO interference were investigated carefully in different physiological situations.

Part II. Hydrothermal steel slag valorization: hydrogen and nano-magnetite production

NASA Astrophysics Data System (ADS)

Crouzet, Camille; Brunet, Fabrice; Recham, Nadir; Auzende, Anne-Line; Findling, Nathaniel; Magnin, Valérie; Ferrasse, Jean-Henry; Goffé, Bruno

2017-10-01

The effect of acidic conditions (in a pH range of 3 to 6) and temperature on the kinetics of the hydrothermal oxidation of ferrous iron contained in BOF steel slag has been tested in the 150 – 350°C range for acid acetic concentrations from 0 to 4M. Reaction progress was monitored with the amount of produced H2. Higher temperature and lower pH are found to enhance the hydrothermal oxidation kinetics of the slag. These two parameters are believed to increase iron dissolution rate which has already been identified as the rate limiting step of the hydrothermal oxidation of pure FeO. An activation energy of 28 × 4 kJ/mole is found for the hydrothermal oxidation of the steel slag which compares very well with that of pure FeO under similar conditions. In the case of the slag run in water at 300°C for 70.5 hours, magnetite product has been separated magnetically and characterized. Particles were found to fall in three size ranges: 10 – 30 nm, 100 – 300 nm and 1 – 10 µm. The smallest fraction (10 – 30 nm) is comparable to the 10 – 20 nm size range that is achieved when nanomagnetite are synthesized by co-precipitation methods. Obviously, the production of nanomagnetite enhances the economic interest of the hydrothermal processing of steel slags, which has already proven its capacity to produce high-purity H2.

Distribution and Emission of Methane in Nakdong Estuary

NASA Astrophysics Data System (ADS)

Ryu, J.; An, S.

2014-12-01

Despite a small area, coastal areas contribute most to the oceanic methane flux. A wide range of methane fluxes have been reported in the coastal areas, but limited data were presented for Korean coastal areas. The air and surface water was sampled in Nakdong Estuary where the barrage had been constructed, and methane concentrations were measured using Gas Chromatography. To see the influence of the barrage, surface water was sampled outside and inside the barrage respectively. In the expectation that methane distribution would be different depending on the tides, surface water outside the barrage was collected at high and low tide respectively. Headspace technique and Membrane Inlet Mass Spectrometry were also used. The average atmospheric concentration (1.82ppm) was lower than the global average concentration expected from the IPCC scenario. The concentrations of water inside the barrage (average 173nM) were similar to those measured in other rivers but in the lower side. The average concentrations outside the barrage (52nM at high tide, 85nM at low tide) were lower than those measured in other coastal areas, but of the same order of magnitude as the European tidal estuaries. Methane concentrations in Nakdong estuary were higher than the methane concentration equilibrated with the atmosphere. The spatial variability of methane concentration in Nakdong estuary seems to be the result of the fresh (high methane) and sea (low methane) water mixing. Meanwhile large tidal flat area in Nakdong estuary should play a major role in methane dynamics and methane flux measurements during sediment incubation were conducted to evaluate the immersion/emersion cycle and photosynthesis by MPB (micro phyto benthos) effect.

Monitor for detecting and assessing exposure to airborne nanoparticles

NASA Astrophysics Data System (ADS)

Marra, Johan; Voetz, Matthias; Kiesling, Heinz-Jürgen

2010-01-01

An important safety aspect of the workplace environment concerns the severity of its air pollution with nanoparticles (NP; <100 nm) and ultrafine particles (UFP; <300 nm). Depending on their size and chemical nature, exposure to these particles through inhalation can be hazardous because of their intrinsic ability to deposit in the deep lung regions and the possibility to subsequently pass into the blood stream. Recommended safety measures in the nanomaterials industry are pragmatic, aiming at exposure minimization in general, and advocating continuous control by monitoring both the workplace air pollution level and the personal exposure to airborne NPs. This article describes the design and operation of the Aerasense NP monitor that enables intelligence gathering in particular with respect to airborne particles in the 10-300 nm size range. The NP monitor provides real time information about their number concentration, average size, and surface areas per unit volume of inhaled air that deposit in the various compartments of the respiratory tract. The monitor's functionality relies on electrical charging of airborne particles and subsequent measurements of the total particle charge concentration under various conditions. Information obtained with the NP monitor in a typical workplace environment has been compared with simultaneously recorded data from a Scanning Mobility Particle Sizer (SMPS) capable of measuring the particle size distribution in the 11-1086 nm size range. When the toxicological properties of the engineered and/or released particles in the workplace are known, personal exposure monitoring allows a risk assessment to be made for a worker during each workday, when the workplace-produced particles can be distinguished from other (ambient) particles.

Ice-nucleating particle concentrations unaffected by urban air pollution in Beijing, China

NASA Astrophysics Data System (ADS)

Chen, Jie; Wu, Zhijun; Augustin-Bauditz, Stefanie; Grawe, Sarah; Hartmann, Markus; Pei, Xiangyu; Liu, Zirui; Ji, Dongsheng; Wex, Heike

2018-03-01

Exceedingly high levels of PM2.5 with complex chemical composition occur frequently in China. It has been speculated whether anthropogenic PM2.5 may significantly contribute to ice-nucleating particles (INP). However, few studies have focused on the ice-nucleating properties of urban particles. In this work, two ice-nucleating droplet arrays have been used to determine the atmospheric number concentration of INP (NINP) in the range from -6 to -25 °C in Beijing. No correlations between NINP and either PM2.5 or black carbon mass concentrations were found, although both varied by more than a factor of 30 during the sampling period. Similarly, there were no correlations between NINP and either total particle number concentration or number concentrations for particles with diameters > 500 nm. Furthermore, there was no clear difference between day and night samples. All these results indicate that Beijing air pollution did not increase or decrease INP concentrations in the examined temperature range above values observed in nonurban areas; hence, the background INP concentrations might not be anthropogenically influenced as far as urban air pollution is concerned, at least in the examined temperature range.

Fluorescence Studies of Protein Crystal Nucleation

NASA Technical Reports Server (NTRS)

Pusey, Marc L.

1999-01-01

Fluorescence can be used to study protein crystal nucleation through methods such as anisotropy, quenching, and resonance energy transfer (FRET), to follow pH and ionic strength changes, and follow events occurring at the growth interface. We have postulated, based upon a range of experimental evidence that the growth unit of tetragonal hen egg white lysozyme is an octamer. Several fluorescent derivatives of chicken egg white lysozyme have been prepared. The fluorescent probes lucifer yellow (LY), cascade blue, and 5-((2-aminoethyl)aminonapthalene-1-sulfonic acid (EDANS), have been covalently attached to ASP 101. All crystallize in the characteristic tetragonal form, indicating that the bound probes are likely laying within the active site cleft. Crystals of the LY and EDANS derivatives have been found to diffract to at least 1.7 A. A second group of derivatives is to the N-terminal amine group, and these do not crystallize as this site is part of the contact region between the adjacent 43 helix chains. However derivatives at these sites would not interfere with formation of the 43 helices in solution. Preliminary FRET studies have been carried out using N-terminal bound pyrene acetic acid (Ex 340 nm, Em 376 nm) lysozyme as a donor and LY (Ex -425 nm, Em 525 nm) labeled lysozyme as an acceptor. FRET data have been obtained at pH 4.6, 0.1 M NaAc buffer, at 5 and 7% NaCl, 4 C. The corresponding Csat values are 0.471 and 0.362 mg/ml (approximately 3.3 and approximately 2.5 x 10(exp -5) M respectively). The data at both salt concentrations show a consistent trend of decreasing fluorescence intensity of the donor species (PAA) with increasing total protein concentration. This decrease is more pronounced at 7% NaCl, consistent with the expected increased intermolecular interactions at higher salt concentrations reflected in the lower solubility. The calculated average distance between any two protein molecules at 5 x 10(exp -6) M is approximately 70nm, well beyond the range where any FRET can be expected. Results from these and ongoing studies will be presented.

Ion beam synthesis of ZrC{sub x}O{sub y} nanoparticles in cubic zirconia

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

Velişa, Gihan, E-mail: gihan@tandem.nipne.ro; Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O.B. MG-6, 077125 Magurele; Mylonas, Stamatis

2016-04-28

{110}-oriented yttria-stabilized zirconia single crystals have been implanted with low-energy C ions in an axial direction, at room temperature and at 550 °C. Room temperature ion implantation generated a damage layer that contains the expected dislocation loop clusters. Strikingly, the high temperature implantation produced zirconium oxycarbide nanoparticles (ZrC{sub x}O{sub y}) at a shallow depth in the yttria-stabilized cubic zirconia crystal, with a diameter in the range of 4–10 nm. Moreover, in the high concentration region of implanted C ions, between 100 and 150 nm below the surface, a number of large precipitates, up to 20 nm, were observed.

Application of tethered balloon for studying vertical distribution of air pollutants within lower tropsphere of Shanghai

NASA Astrophysics Data System (ADS)

Zhang, K.; Wang, D.; Fu, Q.; Xiu, G.; Duan, Y.

2016-12-01

Tethered balloon-based measurement campaign of particle number concentration (PNC) and particle number size distribution (PNSD) in the range of 15.7-661.2 nm was conducted within the lower troposphere of 1000 m in Shanghai, a Chinses megacity, in December 2015. The meteorological condition, PNC, and PNSD were synchronous measured at ground-based station as well as on the tethered balloon. Overall, the mixing layer height (MLH) showed a peak at about LST 14:00-15:00. On ground level, the 88.2 nm particles had the highest number concentration. The Pearson correlation analysis based on the ground level data shows the Pearson correlation coefficient between PNC and NO2was 0.774. The synchronous measurement of PNC and PNSD on ground level and on the tethered balloon showed the 15.7-200 nm particles had higher PNC on ground level, but the PNC of 200-661.2 nm particles are higher at 400 m. And the wind condition showed a strong influence on PNC.The vertical profiles of meteorological parameters and air pollutants was observed. The particle mass concentration, ozone concentration, temperature, and humidity all showed a quick change when the balloon across the atmosphere boundary layer. One episodic haze event (Dec 22nd-Dec 23rd) was selected with specific focus on the variation of PNSD and PNC vertical profiles. Before the haze, the PNC at ground was 9281 cm-3. The MaxDm (the particle diameter with the highest number concentration) was 53.3 nm at that time. Due to the shallow MLH, the MaxDm changed rapidly to 126.3 nm at 321 m. During the haze, the MaxDm and the PNC on ground level was 126.3 nm and 18515 cm-3 respectively. And a quick drop of PNC was observed at 553 m. This may due to the change of wind direction, temperature, and relative humidity. At the end of haze, the MaxDm and the PNC on ground level was 126.3 nm and 10711 cm-3 respectively. The highest MaxDm during those three launches all appeared at a high altitude, usually above 300 m. This result is consisted with the synchronous measurement on December 21st to some degree. This study provides a first insight of PNSD vertical profiles over Eastern China, which will greatly improve the kownledge of the characteristics of particles within the lower tropsphere.

Composite fluorescent nanoparticles for biomedical imaging.

PubMed

Pansare, Vikram J; Bruzek, Matthew J; Adamson, Douglas H; Anthony, John; Prud'homme, Robert K

2014-04-01

In the rapidly expanding field of biomedical imaging, there is a need for nontoxic, photostable, and nonquenching fluorophores for fluorescent imaging. We have successfully encapsulated a new, extremely hydrophobic, pentacene-based fluorescent dye within polymeric nanoparticles (NPs) or nanocarriers (NCs) via the Flash NanoPrecipitation (FNP) process. Nanoparticles and dye-loaded micelles were formulated by FNP and characterized by dynamic light scattering, fluorescence spectroscopy, UV-VIS absorbance spectroscopy, and confocal microscopy. These fluorescent particles were loaded from less than 1% to 78% by weight core loading and the fluorescence maximum was found to be at 2.3 wt.%. The particles were also stably formed at 2.3% core loading from 20 up to 250 nm in diameter with per-particle fluorescence scaling linearly with the NC core volume. The major absorption peaks are at 458, 575, and 625 nm, and the major emission peaks at 635 and 695 nm. In solution, the Et-TP5 dye displays a strong concentration-dependent ratio of the emission intensities of the first two emission peaks, whereas in the nanoparticle core the spectrum is independent of concentration over the entire concentration range. A model of the fluorescence quenching was consistent with Förster resonant energy transfer as the cause of the quenching observed for Et-TP5. The Förster radius calculated from the absorption and emission spectra of Et-TP5 is 4.1 nm, whereas the average dye spacing in the particles at the maximum fluorescence is 3.9 nm. We have successfully encapsulated Et-TP5, a pentacene derivative dye previously only used in light-emitting diode applications, within NCs via the FNP process. The extreme hydrophobicity of the dye keeps it encapsulated in the NC core, its extended pentacene structure gives it relatively long wavelength emission at 695 nm, and the pentacene structure, without oxygen or nitrogen atoms in its core, makes it highly resistant to photobleaching. Its bulky side groups minimize self-quenching and localization within the nanoparticle core prevents interaction of the dye with biological surfaces, or molecules in diagnostic assays. Loading of dye in the NP core allows 25 times more dye to be delivered than if it were conjugated onto the nanocarrier surface. The utility of the dye for quantifying nanoparticle binding is demonstrated. Studies to extend the wavelength range of these pentacene dyes into the near infra-red are underway.

Casein maps: Effect of ethanol, pH, temperature, and CaCl2 on the particle size of reconstituted casein micelles

PubMed Central

Ye, Ran; Harte, Federico

2015-01-01

Although conditions favoring casein micelle aggregation are well known, factors promoting the dissociation of the casein micelle are not fully understood. It was our objective to investigate the ethanol-induced dissociation of micellar casein as affected by temperature and a wide range of pH, along with the concentrations of calcium and casein. Two different concentrations of casein micelles were dispersed in imidazole buffer with 0 to 80% ethanol (vol/vol) and 2 and 10 mM calcium. Apparent micelle size was determined by dynamic light scattering at 5, 30, and 60°C. In the absence of ethanol, casein precipitation occurred at pH 4.6 in imidazole buffer. Ten to forty percent ethanol promoted casein aggregation (>1,000 nm) and higher temperature (30 and 60°C) enhanced this effect. Higher ethanol concentrations at 50 to 80% induced the dissociation (<40 nm) of the casein micelle upon acidification (pH <5) and alkalization (pH >8) in imidazole buffer. In addition, higher concentrations of casein (0.25 mg/mL) and calcium (20 mM) caused the formation of larger aggregates (>1,000 nm) in the presence of ethanol when comparing with the initial lower concentrations of casein (0.1 mg/mL) and calcium (2 mM). Casein micelle dissociation can be achieved near the isoelectric pH by modifying the solvent composition and temperature. PMID:23200467

Casein maps: effect of ethanol, pH, temperature, and CaCl2 on the particle size of reconstituted casein micelles.

PubMed

Ye, Ran; Harte, Federico

2013-02-01

Although conditions favoring casein micelle aggregation are well known, factors promoting the dissociation of the casein micelle are not fully understood. It was our objective to investigate the ethanol-induced dissociation of micellar casein as affected by temperature and a wide range of pH, along with the concentrations of calcium and casein. Two different concentrations of casein micelles were dispersed in imidazole buffer with 0 to 80% ethanol (vol/vol) and 2 and 10mM calcium. Apparent micelle size was determined by dynamic light scattering at 5, 30, and 60°C. In the absence of ethanol, casein precipitation occurred at pH 4.6 in imidazole buffer. Ten to forty percent ethanol promoted casein aggregation (>1,000 nm) and higher temperature (30 and 60°C) enhanced this effect. Higher ethanol concentrations at 50 to 80% induced the dissociation (<40 nm) of the casein micelle upon acidification (pH <5) and alkalization (pH>8) in imidazole buffer. In addition, higher concentrations of casein (0.25mg/mL) and calcium (20mM) caused the formation of larger aggregates (>1,000 nm) in the presence of ethanol when comparing with the initial lower concentrations of casein (0.1mg/mL) and calcium (2mM). Casein micelle dissociation can be achieved near the isoelectric pH by modifying the solvent composition and temperature. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The photoactivity of titanium dioxide coatings with silver nanoparticles prepared by sol-gel and reactive magnetron sputtering methods - comparative studies

NASA Astrophysics Data System (ADS)

Kądzioła, Kinga; Piwoński, Ireneusz; Kisielewska, Aneta; Szczukocki, Dominik; Krawczyk, Barbara; Sielski, Jan

2014-01-01

Titanium dioxide coatings were deposited on silicon substrates using two different methods: sol-gel dip-coating (SG) and reactive magnetron sputtering (MS). In order to obtain anatase phase, as-prepared coatings were calcined at 500 °C in air. Subsequently, silver nanoparticles (AgNPs) were grown on the surface of TiO2 coatings by photoreduction of silver ions, initiated by illumination of the UV lamp operated at λ = 365 nm. The concentrations of silver ions were 0.1 mmol dm-3 and 1.0 mmol dm-3. Coatings immersed in these solutions were illuminated during 5 min and 30 min. The coating thicknesses, evaluated by ellipsometry, were 118 nm and 147 nm for SG and MS methods, respectively. Atomic force microscopy (AFM) imaging revealed that the surface roughness of TiO2 coating prepared by MS is about 6 times larger as compared to coatings prepared by SG method. The size of AgNPs deposited on SG and MS coatings were in the range of 17-132 nm and 54-103 nm respectively. The photoactivity of AgNPs/TiO2 coatings was determined by the measurement of the decomposition rate of bisphenol A (BPA). The concentration of BPA before and after illumination under UV light (λ = 365 nm) was monitored by high-performance liquid chromatography (HPLC). It was found that AgNPs enhance the photoactivity of the TiO2 coatings.

Evaluations of the Method to Measure Black Carbon Particles Suspended in Rainwater and Snow Samples

NASA Astrophysics Data System (ADS)

Ohata, S.; Moteki, N.; Schwarz, J. P.; Fahey, D. W.; Kondo, Y.

2012-12-01

The mass concentrations and size distributions of black carbon (BC) particles in rainwater and snow are important parameters for improved understanding of the wet deposition of BC, is a key process in quantifying the impacts of BC on climate. In this study, we have evaluated a new method to measure these parameters. The approach consists of an ultrasonic nebulizer (USN) used in conjunction with a Single Particle Soot Photometer (SP2). The USN converts sample water into micron-size droplets at a constant rate and then extracts airborne BC particles by dehydrating the water droplets. The mass of individual BC particles is measured by the SP2, based on the laser-induced incandescence technique. The combination of the USN and SP2 enabled the measurement of BC particles using only small amount of sample water, typically 10 ml (Ohata et al., 2011). However, the loss of BC during the extraction process depends on their size. We determined the size-dependent extraction efficiency using polystyrene latex spheres (PSLs) with twelve different diameters between 100-1050 nm. The PSL concentrations in water were determined by the light extinction of at 532nm. The extraction efficiency of the USN showed broad maximum in the diameter range of 200-500nm, and decreased substantially at larger sizes. The extraction efficiency determined using the PSL standards agreed to within ±40% with that determined using laboratory-generated BC concentration standards. We applied this method to the analysis of rainwater collected in Tokyo and Okinawa over the East China Sea. Measured BC size distributions in all rainwater samples showed negligible contribution of the BC particles larger than 600nm to the total BC amounts. However, for BC particles in surface snow collected in Greenland and Antarctica, size distributions were sometimes shifted to much larger size ranges.

Occupational exposure to ultrafine particles in police officers: no evidence for adverse respiratory effects.

PubMed

Jordakieva, G; Grabovac, I; Valic, E; Schmidt, K E; Graff, A; Schuster, A; Hoffmann-Sommergruber, K; Oberhuber, C; Scheiner, O; Goll, A; Godnic-Cvar, J

2018-01-01

Inhalation exposure to fine and ultrafine particles (UFPs) has been associated with respiratory diseases. However, little is known on the quality, threshold levels and concentration of these particles causing adverse health effects. The impact of occupational exposure to submicrometer and UFPs was assessed in 30 healthy police shooting instructors by clinical investigation, self-assessment questionnaire, sputum and spirometry and compared to a control group. General laboratory chemistry parameters, circulating cytokines (interleukin [IL]-2, IL-4, IL-5, IL-6, IL-8, interferon-gamma [IFN-γ]), and granulocyte macrophage colony-stimulating factor (GM-CSF) in serum were measured. UFP exposure was recorded by Scanning Mobility Particle Sizer. Concentrations of submicrometer sized airborne particles (< 700 nm) measured between 3.34 × 10 5 /cm 3 and 7.58 × 10 5 /cm 3 at shooting sites, with highest concentrations found in the UFP range (< 100 nm). The size of the monodispersed particles ranged from 54.74 ± 16.25 nm to 98.19 ± 22.83 nm. Short term exposure (4 h) to high levels of UFPs caused an increase of IFN-γ in exposed subjects ( p  = 0.022). 24 h after exposure a significant decrease of IgG, albumin fibrinogen and factor VII was found. Neither directly after 4 h of high levels UFPs exposure nor 24 h after exposure subjective complaints or objective measurements indicating adverse respiratory effects in exposed subjects were found. No consistent indications for adverse respiratory or inflammatory effects directly following exposure and 24 h after exposure to high levels of UFPs in our study group were detected. However we showed the assessment of short-term exposure effects at a genuine occupational setting, which might is relevant when a risk assessment of high level occupational exposures to UFPs is considered.

Validated spectrofluorometric methods for determination of amlodipine besylate in tablets

NASA Astrophysics Data System (ADS)

Abdel-Wadood, Hanaa M.; Mohamed, Niveen A.; Mahmoud, Ashraf M.

2008-08-01

Two simple and sensitive spectrofluorometric methods have been developed and validated for determination of amlodipine besylate (AML) in tablets. The first method was based on the condensation reaction of AML with ninhydrin and phenylacetaldehyde in buffered medium (pH 7.0) resulting in formation of a green fluorescent product, which exhibits excitation and emission maxima at 375 and 480 nm, respectively. The second method was based on the reaction of AML with 7-chloro-4-nitro-2,1,3-benzoxadiazole (NBD-Cl) in a buffered medium (pH 8.6) resulting in formation of a highly fluorescent product, which was measured fluorometrically at 535 nm ( λex, 480 nm). The factors affecting the reactions were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9949-0.9997) were found between the fluorescence intensity and the concentrations of AML in the concentration range of 0.35-1.8 and 0.55-3.0 μg ml -1 for ninhydrin and NBD-Cl methods, respectively. The limits of assays detection were 0.09 and 0.16 μg ml -1 for the first and second method, respectively. The precisions of the methods were satisfactory; the relative standard deviations were ranged from 1.69 to 1.98%. The proposed methods were successfully applied to the analysis of AML in pure and pharmaceutical dosage forms with good accuracy; the recovery percentages ranged from 100.4-100.8 ± 1.70-2.32%. The results were compared favorably with those of the reported method.

Nondestructive identification of dye mixtures in polyester and cotton fibers using raman spectroscopy and ultraviolet-visible (UV-Vis) microspectrophotometry.

PubMed

Was-Gubala, Jolanta; Starczak, Roza

2015-01-01

Presented in this paper is an assessment of the applicability of Raman spectroscopy and microspectrophotometry (MSP) in visible and ultraviolet light (UV-Vis) in the examination of textile fibers dyed with mixtures of synthetic dyes. Fragments of single polyester fibers, stained with ternary mixtures of disperse dyes in small mass concentrations, and fragments of single cotton fibers, dyed with binary or ternary mixtures of reactive dyes, were subjected to the study. Three types of excitation sources, 514, 633, and 785 nm, were used during Raman examinations, while the MSP study was conducted in the 200 to 800 nm range. The results indicate that the capabilities for discernment of dye mixtures are similar in the spectroscopic methods that were employed. Both methods have a limited capacity to distinguish slightly dyed polyester fiber; additionally, it was found that Raman spectroscopy enables identification of primarily the major components in dye mixtures. The best results, in terms of the quality of Raman spectra, were obtained using an excitation source from the near infrared. MSP studies led to the conclusion that polyester testing should be carried out in the range above 310 nm, while for cotton fibers there is no limitation or restriction of the applied range. Also, MSP UV-Vis showed limited possibilities for discriminatory analysis of cotton fibers dyed with a mixture of reactive dyes, where the ratio of the concentration of the main dye used in the dyeing process to minor dye was higher than four. The results presented have practical applications in forensic studies, inter alia.

Development of a Raman chemical image detection algorithm for authenticating dry milk

USDA-ARS?s Scientific Manuscript database

This research developed a Raman chemical imaging method for detecting multiple adulterants in skim milk powder. Ammonium sulfate, dicyandiamide, melamine, and urea were mixed into the milk powder as chemical adulterants in the concentration range of 0.1–5.0%. A Raman imaging system using a 785-nm la...

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

Bunkin, N F; Shkirin, A V; Burkhanov, I S

Aqueous NaCl solutions with different concentrations have been investigated by dynamic scattering of laser radiation. It is experimentally shown that these solutions contain scattering particles with a wide size distribution in a range of ∼10 – 100 nm. The experimental results indirectly confirm the existence of quasi-stable gas nanobubbles in the bulk of aqueous ionic solutions. (light scattering)

Generation and stabilization of whey-based monodisperse naoemulsions using ultra-high pressure homogenization and small amphipathic co-emulsifier combinations

USDA-ARS?s Scientific Manuscript database

Ultra-high-pressure homogenization (UHPH) was used to generate monodisperse stable peanut oil nanoemulsions within a desired nanosize range (<100 nm) (DNR) stabilized using combinations of whey protein concentrate (WPC), sodium dodecyl sulfate, Triton X-100 (X100), and zwitterionic sulfobetaine-base...

Tin oxide quantum dots embedded iron oxide composite as efficient lead sensor

NASA Astrophysics Data System (ADS)

Dutta, Dipa; Bahadur, Dhirendra

2018-04-01

SnO2 quantum dots (QDs) embedded iron oxide (IO) nanocomposite is fabricated and explored as a capable sensor for lead detection. Square wave anodic stripping voltammetry (SWASV) and amperometry have been used to explore the proposed sensor's response towards lead detection. The modified electrode shows linear current response for concentration of lead ranging from 99 nM to 6.6 µM with limit of detection 0.42 µM (34 ppb). Amperometry shows a detection limit as low as 0.18 nM (0.015 ppb); which is far below the permissible limit of lead in drinking water by World Health Organization. This proposed sensor shows linear current response (R2 = 0.98) for the lead concentration ranging from 133 × 10-9 to 4.4 × 10-6M. It also exhibits rapid response time of 12 sec with an ultra high sensitivity of 5.5 µA/nM. These detection properties promise the use of SnO2 QDs -IO composite for detection of lead in environmental sample with great ease.

Physical and chemical characterization of fly ashes from Swiss waste incineration plants and determination of the ash fraction in the nanometer range.

PubMed

Buha, Jelena; Mueller, Nicole; Nowack, Bernd; Ulrich, Andrea; Losert, Sabrina; Wang, Jing

2014-05-06

Waste incineration had been identified as an important source of ultrafine air pollutants resulting in elaborated treatment systems for exhaust air. Nowadays, these systems are able to remove almost all ultrafine particles. However, the fate of ultrafine particles caught in the filters has received little attention so far. Based on the use of engineered nano-objects (ENO) and their transfer into the waste stream, it can be expected that not only combustion generated nanoparticles are found in fly ashes but that many ENO finally end up in this matrix. A more detailed characterization of the nanoparticulate fraction of fly ashes is therefore needed. Physical and chemical characterizations were performed for fly ashes from five selected waste incineration plants (WIPs) with different input materials such as municipal waste, wood and sewage sludge. The intrinsic densities of the fly ashes were in the range of 2.7-3.2 g/cm(3). When the fly ash particle became airborne, the effective density depended on the particle size, increasing from 0.7-0.8 g/cm(3) for 100-150 nm to 2 g/cm(3) for 350-500 nm. The fly ash samples were fractionated at 2 μm, yielding fine fractions (<2 μm) and coarse fractions (>2 μm). The size distributions of the fine fractions in the airborne form were further characterized, which allowed calculation of the percentage of the fly ash particles below 100 nm. We found the highest mass-based percentage was about 0.07%; the number percentage in the fine fraction was in the range of 4.8% to 22%. Comparison with modeling results showed that ENO may constitute a considerable part of the fly ash particles below 100 nm. Chemical analyses showed that for the municipal waste samples Ca and Al were present in higher concentrations in the coarse fraction; for the mixed wood and sludge sample the P concentration was higher in the coarse fraction; for most other samples and elements they were enriched in the fine fraction. Electron microscopic images of fly ashes showed a wide range of particle sizes, from nanometer range to micrometer range. Many aggregated particles were observed, demonstrating that ENO, bulk-derived nano-objects and combustion-generated nano-objects can form aggregates in the incineration process.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric; Carey, James Edward

2017-10-17

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric [Concord, MA; Carey, III, James E.

2011-02-08

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric; Carey, III, James E.

2010-08-24

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric [Concord, MA; Carey, III, James Edward

2009-03-17

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Carey, III, James Edward; Mazur, Eric [Concord, MA

2011-12-20

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Carey, III, James Edward; Mazur, Eric

2006-06-06

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric; Carey, James Edward

2016-03-01

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity greater than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelengths, e.g., up to about 3.5 microns.

Silicon-based visible and near-infrared optoelectric devices

DOEpatents

Mazur, Eric; Carey, James Edward

2013-12-10

In one aspect, the present invention provides a silicon photodetector having a surface layer that is doped with sulfur inclusions with an average concentration in a range of about 0.5 atom percent to about 1.5 atom percent. The surface layer forms a diode junction with an underlying portion of the substrate. A plurality of electrical contacts allow application of a reverse bias voltage to the junction in order to facilitate generation of an electrical signal, e.g., a photocurrent, in response to irradiation of the surface layer. The photodetector exhibits a responsivity great than about 1 A/W for incident wavelengths in a range of about 250 nm to about 1050 nm, and a responsivity greater than about 0.1 A/W for longer wavelenths, e.g., up to about 3.5 microns.

Effects of Raman scattering on the water-leaving radiance

NASA Technical Reports Server (NTRS)

Waters, Kirk J.

1995-01-01

The contribution of Raman scattering to the water-leaving radiance is examined using Monte Carlo simulations. Exit angle information is retained, allowing a comparison of different satellite viewing directions. Chlorophyll values of 0.0, 0.01, 0.1, and 1.0 mg Chl/cu m are simulated. Little directional variability is found, with the exception of the direct solar backscatter direction. The wavelength variability is greatest for low chlorophyll concentrations and is negligible for 1.0 mg Chl/cu m. At 550 nm the Raman contribution ranges from approximately 18% of the total water-leaving radiance for pure water to 3% for 1.0 mg Chl/cu m. At 440 nm the range is from 6% to 2%, indicating that Raman scattering will impact radiance ratios for ocean color satellite algorithms.

Mg-Doped Hydroxyapatite/Chitosan Composite Coated 316L Stainless Steel Implants for Biomedical Applications.

PubMed

Sutha, S; Dhineshbabu, N R; Prabhu, M; Rajendran, V

2015-06-01

In this investigation, ultrasonication process was used for the synthesis of magnesium doped nano-hydroxyapatite (MH) (0, 1, 2, and 3 mol% of Mg concentration) particles with controlled size and surface morphology. The size of the prepared MH particles was in the range of 20-100 nm with narrow distribution. Increase in the concentration of Mg reduced the particle size distribution from 60 to 40 nm. On incorporation of Mg in HAp lattice, an increase of 20-66 nm in specific surface area was observed in microporous HAp particles. XRF and XRD patterns reveal that the particles possess stoichiometric composition with reduced crystallinity with respect to the Mg concentration. Surface morphology of MH/chitosan (CTS) coated implant was found to be uniform without any defects. The corrosion rate of the implant decreased with increase in Mg concentration. The in vitro formation of bonelike apatite layer on the surface of the MH/CTS coated implant was observed from simulated body fluid studies. The antimicrobial activity of the MH/CTS composites against gram-positive and gram-negative bacterial strains indicated that increasing Mg concentration enhanced antimicrobial properties. Nanoindentation analysis of apatite coated implant surface reveals that the mechanical property depends on the concentration of magnesium in HAp. From the cytotoxicity analysis against NIH 3T3 fibroblast, it was observed that the Mg incorporated HAp/CTS composite was less toxic than the MHO/CTS composite. From this result, it was concluded that the MH/CTS nanocomposites coated implant is the excellent material for implants.

Highly Luminescent Water-Dispersible NIR-Emitting Wurtzite CuInS2/ZnS Core/Shell Colloidal Quantum Dots

PubMed Central

2017-01-01

Copper indium sulfide (CIS) quantum dots (QDs) are attractive as labels for biomedical imaging, since they have large absorption coefficients across a broad spectral range, size- and composition-tunable photoluminescence from the visible to the near-infrared, and low toxicity. However, the application of NIR-emitting CIS QDs is still hindered by large size and shape dispersions and low photoluminescence quantum yields (PLQYs). In this work, we develop an efficient pathway to synthesize highly luminescent NIR-emitting wurtzite CIS/ZnS QDs, starting from template Cu2-xS nanocrystals (NCs), which are converted by topotactic partial Cu+ for In3+ exchange into CIS NCs. These NCs are subsequently used as cores for the overgrowth of ZnS shells (≤1 nm thick). The CIS/ZnS core/shell QDs exhibit PL tunability from the first to the second NIR window (750–1100 nm), with PLQYs ranging from 75% (at 820 nm) to 25% (at 1050 nm), and can be readily transferred to water upon exchange of the native ligands for mercaptoundecanoic acid. The resulting water-dispersible CIS/ZnS QDs possess good colloidal stability over at least 6 months and PLQYs ranging from 39% (at 820 nm) to 6% (at 1050 nm). These PLQYs are superior to those of commonly available water-soluble NIR-fluorophores (dyes and QDs), making the hydrophilic CIS/ZnS QDs developed in this work promising candidates for further application as NIR emitters in bioimaging. The hydrophobic CIS/ZnS QDs obtained immediately after the ZnS shelling are also attractive as fluorophores in luminescent solar concentrators. PMID:28638177

Colorimetric detection of melamine in milk by using gold nanoparticles-based LSPR via optical fibers

PubMed Central

Chang, Keke; Wang, Shun; Zhang, Hao; Guo, Qingqian; Hu, Xinran; Lin, Zhili; Sun, Haifeng; Jiang, Min

2017-01-01

A biosensing system with optical fibers is proposed for the colorimetric detection of melamine in liquid milk samples by using the localized surface plasmon resonance (LSPR) of unmodified gold nanoparticles (AuNPs). The biosensing system consists of a broadband light source that covers the spectral range from 200 nm to 1700 nm, an optical attenuator, three types of 600 μm premium optical fibers with SMA905 connectors and a miniature spectrometer with a linear charge coupled device (CCD) array. The biosensing system with optical fibers is low-cost, simple and is well-proven for the detection of melamine. Its working principle is based on the color changes of AuNPs solution from wine-red to blue due to the inter-particle coupling effect that causes the shifts of wavelength and absorbance in LSPR band after the to-be-measured melamine samples were added. Under the optimized conditions, the detection response of the LSPR biosensing system was found to be linear in melamine detection in the concentration range from 0μM to 0.9 μM with a correlation coefficient (R2) 0.99 and a detection limit 33 nM. The experimental results obtained from the established LSPR biosensing system in the actual detection of melamine concentration in liquid milk samples show that this technique is highly specific and sensitive and would have a huge application prospects. PMID:28475597

Absorption spectra and nonlinear transmission (at λ = 2940 nm) of a diffusion-doped Fe{sup 2+}:ZnSe single crystal

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

Bufetova, G A; Gulyamova, E S; Il'ichev, N N

2015-06-30

Transmission spectra of a ZnSe sample diffusion-doped with Fe{sup 2+} ions have been measured in the wavelength range 500 – 7000 nm. A broad absorption band in the range 500 – 1500 nm has been observed in both doped and undoped regions of the sample. This band is possibly due to deviations from stoichiometry in the course of diffusion doping. The transmission of the Fe{sup 2+}:ZnSe sample at a wavelength of 2940 nm has been measured at various dopant concentrations and high peak pulse intensities (up to 8 MW cm{sup -2}). The samples have been shown to be incompletely bleached:more » during a laser pulse, the transmission first increases, reaches a maximum, and then falls off. Our results suggest that the incomplete bleaching cannot be accounted for by excited-state absorption. The incomplete bleaching (as well as the transmission maximum) is due to the heating of the sample, which leads to a reduction in upper level lifetime and, accordingly, to an increase in absorption saturation intensity. (nonlinear optical phenomena)« less

Assessment of the performance of a compact concentric spectrometer system for Atmospheric Differential Optical Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Whyte, C.; Leigh, R. J.; Lobb, D.; Williams, T.; Remedios, J. J.; Cutter, M.; Monks, P. S.

2009-08-01

A breadboard demonstrator of a novel UV/VIS grating spectrometer for atmospheric research has been developed based upon a concentric arrangement of a spherical meniscus lens, concave spherical mirror and curved diffraction grating suitable for a range of remote sensing applications from the ground or space. The spectrometer is compact and provides high optical efficiency and performance benefits over traditional instruments. The concentric design is capable of handling high relative apertures, owing to spherical aberration and coma being near zero at all surfaces. The design also provides correction for transverse chromatic aberration and distortion, in addition to correcting for the distortion called "smile", the curvature of the slit image formed at each wavelength. These properties render this design capable of superior spectral and spatial performance with size and weight budgets significantly lower than standard configurations. This form of spectrometer design offers the potential for an exceptionally compact instrument for differential optical absorption spectroscopy (DOAS) applications particularly from space (LEO, GEO orbits) and from HAPs or ground-based platforms. The breadboard demonstrator has been shown to offer high throughput and a stable Gaussian line shape with a spectral range from 300 to 450 nm at better than 0.5 nm resolution, suitable for a number of typical DOAS applications.

New in situ Aerosol Spectral Optical Measurements over 300-700 nm, Extinction and Total Absorption, Paired with Absorption from Water- and Methanol-soluble Aerosol Extracts

NASA Astrophysics Data System (ADS)

Jordan, C. E.; Stauffer, R. M.; Lamb, B.; Novak, M. G.; Mannino, A.; Hudgins, C.; Thornhill, K. L., II; Crosbie, E.; Winstead, E.; Anderson, B.; Martin, R.; Shook, M.; Ziemba, L. D.; Beyersdorf, A. J.; Corr, C.

2017-12-01

A new in situ spectral aerosol extinction instrument (custom built, SpEx) built to cover the 300-700 nm range at 1 nm spectral resolution and temporal resolution of 4 minutes was deployed on the top deck ( 10 m above the water surface) of the R/V Onnuri during the KORUS-OC research cruise around South Korea in spring 2016. This new instrument was one component of a suite of in situ aerosol optical measurements that included 3-visible-wavelength scattering (Airphoton IN101 Nephelometer, at 450, 532, & 632 nm) and absorption (Brechtel Tricolor Absorption Photometer Model 2901, at 467, 528, & 652 nm) with sub-minute temporal resolution; two sets of filters (Teflon and glass fiber, both collected over 3 hour daytime and 12 hour overnight intervals) to provide aerosol absorption spectra over the same wavelength range as SpEx. The glass fiber filters were placed in the center of an integrating sphere (Labsphere DRA-CA-30) attached to a dual beam spectrophotometer (Cary 100 Bio UV-Visible Spectrophotometer) to measure total aerosol absorption spectra via an established method used by the ocean color community to obtain absorption spectra from particles suspended in sea water. Adapting this methodology for atmospheric aerosol measurements provides a new avenue to obtain spectral total aerosol absorption, particularly useful for expanding in situ measurement capabilities into the UV range. The Teflon filters were cut in half with one half extracted in deionized water and the other half extracted in methanol. The solutions were filtered and injected into a liquid waveguide capillary cell (World Precision Instruments LWCC-3100, 100 cm pathlength) to measure the absorption spectra for each solution. In addition, the water extracts were measured via ion chromatography (Dionex ICS-3000 Ion Chromatography System) to obtain water-soluble inorganic ion concentrations, as well as via aerosol mass spectrometry (Aerodyne Research, Inc. HR-ToF High Resolution Aerosol Mass Spectrometer) to obtain organic aerosol concentrations. Results from the KORUS-OC data set will be discussed. In particular, the relationships between the optical information and chemical information will be examined.

[Study of cholesterol concentration based on serum UV-visible absorption spectrum].

PubMed

Zhu, Wei-Hua; Zhao, Zhi-Min; Guo, Xin; Chen, Hui

2009-04-01

In the present paper, UV-visible absorption spectrum and neural network theory were used for the analysis of cholesterol concentration. Experimental investigation shows that the absorption spectrum has the following characteristics in the wave band of 350-600 nm: (1) There is a stronger absorption peak at 416 nm for the test sample with different cholesterol concentration; (2) There is a shoulder peak between 450 and 500 nm, whose central wavelength is 460 nm; (3) There is a weaker peak at 578 nm; (4) Absorption spectrums shape of different cholesterol concentration is different obviously. The absorption spectrum of serum is the synthesis result of cholesterol and other components (such as sugar), and the information is contained at each wavelength. There is no significant correlation between absorbance and cholesterol content at 416 nm, showing a random relation, so whether cholesterol content is abnormal is not determined by the absorbance peak at 416 nm. Based on the evident correlation between serum absorption spectrum and cholesterol concentration in the wave band of 455-475 nm, a neural network model was built to predict the cholesterol concentration. The correlation coefficient between predicted cholesterol content output A and objectives T reaches 0.968, which can be regarded as better prediction, and it provides a spectra test method of cholesterol concentration.

Rapid Real-time Electrical Detection of Proteins Using Single Conducting Polymer Nanowire-Based Microfluidic Aptasensor

PubMed Central

Huang, Jiyong; Luo, Xiliang; Lee, Innam; Hu, Yushi; Cui, Xinyan Tracy; Yun, Minhee

2011-01-01

Single polypyrrole (PPy) nanowire-based microfluidic aptasensors were fabricated using a one-step electrochemical deposition method. The successful incorporation of the aptamers into the PPy nanowire was confirmed by fluorescence microscopy image. The microfluidic aptasensor showed responses to IgE protein solutions in the range from 0.01 nM to 100 nM, and demonstrated excellent specificity and sensitivity with faster response and rapid stabilization times (~20 s). At the lowest examined IgE concentration of 0.01nM, the microfluidic aptasensor still exhibited ~0.32% change in the conductance. The functionality of this aptasensor was able to be regenerated using an acid treatment with no major change in sensitivity. In addition, the detection of cancer biomarker MUC1 was performed using another microfluidic aptasensor, which showed a very low detection limit of 2.66 nM MUC1 compared to commercially available MUC1 diagnosis assay (800 nM). PMID:21937215

Ratiometric fluorescent nanosensor based on carbon dots for the detection of mercury ion

NASA Astrophysics Data System (ADS)

Ma, Yusha; Mei, Jing; Bai, Jianliang; Chen, Xu; Ren, Lili

2018-05-01

A novel ratiometric fluorescent nanosensor based on carbon dots has been synthesized via bonding rhodamine B hydrazide to the carbon dots surface by an amide reaction. The ratiometric fluorescent nanosensor showed only a single blue fluorescence emission around 450 nm. While, as mercury ion was added, due to the open-ring of rhodamine moiety bonded on the CDs surface, the orange emission of the open-ring rhodamine would increase obviously according to the concentration of mercury ion, resulting in the distinguishable dual emissions at 450 nm and 575 nm under a single 360 excitation wavelength. Meanwhile, the ratiometric fluorescent nanosensor based on carbon dots we prepared is more sensitive to qualitative and semi-quantitative detection of mercury ion in the range of 0–100 μM, because fluorescence changes gradually from blue to orange emission under 365 nm lamp with the increasing of mercury ion in the tested solution.

Determination of sunset yellow in soft drinks based on fluorescence quenching of carbon dots

NASA Astrophysics Data System (ADS)

Yuan, Yusheng; Zhao, Xin; Qiao, Man; Zhu, Jinghui; Liu, Shaopu; Yang, Jidong; Hu, Xiaoli

2016-10-01

Fluorescent carbon dots was prepared by heating N-(2-hydroxyethyl)ethylene diaminetriacetic acid in air. The carbon dots were not only highly soluble in water but also uniform in size, and possessed strong blue fluorescence and excitation wavelength-dependent emission properties with the maximum excitation and emission wavelength at 366 nm and 423 nm, respectively. Food colorant sunset yellow whose excitation and emission wavelength at 303 nm and 430 nm could selectively quench the fluorescence of carbon dots, efficient fluorescent resonance energy transfer between the carbon dots and sunset yellow is achieved. This was exploited to design a method for the determination of sunset yellow in the concentration range from 0.3 to 8.0 μmol L- 1, with a limit of detection (3 σ/k) of 79.6 nmol L- 1. Furthermore the fluorimetric detection method was established and validated for sunset yellow in soft drinks samples with satisfactory results.

Laboratory measurements of radiance and reflectance spectra of dilute secondary-treated sewage sludge

NASA Technical Reports Server (NTRS)

Witte, W. G.; Usry, J. W.; Whitlock, C. H.; Gurganus, E. A.

1977-01-01

The National Aeronautics and Space Administration (NASA), in cooperation with the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA), conducted a research program to evaluate the feasibility of remotely monitoring ocean dumping of waste products such as acid and sewage sludge. One aspect of the research program involved the measurements of upwelled spectral signatures for sewage-sludge mixtures of different concentrations in an 11600-liter tank. This paper describes the laboratory arrangement and presents radiance and reflectance spectra in the visible and near-infrared ranges for concentrations ranging from 9.7 to 180 ppm of secondary-treated sewage sludge mixed with two types of base water. Results indicate that upwelled radiance varies in a near-linear manner with concentration and that the sludge has a practically flat signal response between 420 and 970 nm. Reflectance spectra were obtained for the sewage-sludge mixtures at all wavelengths and concentrations.

Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise.

PubMed

Harrison, Michael; Moyna, Niall M; Zderic, Theodore W; O'Gorman, Donal J; McCaffrey, Noel; Carson, Brian P; Hamilton, Marc T

2012-07-10

Many of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects. Using a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL). The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70-120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43-55 nm (medium) particle range. VLDL-TG in smaller particles (29-43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state. These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.

Lipoprotein particle distribution and skeletal muscle lipoprotein lipase activity after acute exercise

PubMed Central

2012-01-01

Background Many of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects. Methods Using a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL). Results The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55 nm (medium) particle range. VLDL-TG in smaller particles (29–43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state. Conclusions These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity. PMID:22672707

Enzyme-functionalized thin-cladding long-period fiber grating in transition mode at dispersion turning point for sugar-level and glucose detection

NASA Astrophysics Data System (ADS)

Badmos, Abdulyezir A.; Sun, Qizhen; Sun, Zhongyuan; Zhang, Junxi; Yan, Zhijun; Lutsyk, Petro; Rozhin, Alex; Zhang, Lin

2017-02-01

Enzyme-functionalized dual-peak long-period fiber grating (LPFG) inscribed in 80-μm-cladding B/Ge codoped single-mode fiber is presented for sugar-level and specific glucose detection. Before enzyme functionalization, the dual-peak LPFG was employed for refractive index sensing and sugar-level detection and high sensitivities of ˜4298.20 nm/RIU and 4.6696 nm/% were obtained, respectively. Glucose detection probe was attained by surface functionalization of the dual-peak LPFG via covalent binding with aminopropyl triethoxysilane used as a binding site. Optical micrographs confirmed the presence of enzyme. The surface-functionalized dual-peak LPFG was tested with D-(+)-glucose solution of different concentrations. While the peak 2 at the longer wavelength was suitable only to measure lower glucose concentration (0.1 to 1.6 mg/ml) recording a high sensitivity of 12.21±0.19 nm/(mg/ml), the peak 1 at the shorter wavelength was able to measure a wider range of glucose concentrations (0.1 to 3.2 mg/ml) exhibiting a maximum resonance wavelength shift of 7.12±0.12 nm/mg/ml. The enzyme-functionalized dual-peak LPFG has the advantage of direct inscription of highly sensitive grating structures in thin-cladding fibre without etching, and most significantly, its sensitivity improvement of approximately one order of magnitude higher than previously reported LPFG and excessively tilted fibre grating (Ex-TFG) for glucose detection.

Synthesis of NiFe2O4 nanoparticles for energy and environment applications

NASA Astrophysics Data System (ADS)

Zhang, Ying; Rimal, Gaurab; Tang, Jinke; Dai, Qilin

2018-02-01

Magnetic nanoparticles are of great interest due to their applications in energy and environment. In this work, we developed a chemical solution based method to synthesize NiFe2O4 (NFO) nanoparticles with different sizes and structures by organic ligands and studied their applications in magnetic electrolyte concentration cells and waste water treatment. NFO nanoparticle growth is controlled by the organic passivating ligand ratios, reaction temperatures, and reaction solution concentrations to achieve the control of NFO nanoparticle size ranging from 25 nm to 160 nm. The NFO growth mechanism is controlled by aggregation related mechanism, leading to tunable magnetic properties and concentration cell device performance. Magnetic biochar consisting of biochar/NFO composite was also obtained based on the developed method. Waste water containing Rhodamine B was tested by the synthesized magnetic biochar. We believe the method developed in this work about magnetic NFO nanoparticles and magnetic biochar will shed light on the application of magnetic nanoparticles in energy and environment.

A near infrared holographic glucose sensor.

PubMed

Vezouviou, Evangelia; Lowe, Christopher R

2015-06-15

Real-time glucose monitoring has been beneficial in reducing health complications associated with diabetes as well as a decrease in mortality. This report describes a novel holographic platform, fabricated via laser ablation on chitosan hydrogel with gold nanoparticles with a replaying in visible and near IR. The sensor responded with a 12 nm and 7 nm shift in wavelength at glucose concentrations in the 0-70 mM range and in the visible and near IR, respectively, at pH 7.4 and an ionic strength of 154 mM. The sensor did not respond to potential interferences found in the interstitial fluid, such as fructose, vitamin C and lactate, at their respective normal concentrations and was stable to fluctuations in temperature, pH and ionic strength. The characteristics of this sensor suggests that it may be applicable for use as an implanted device for the real time monitoring of glucose concentrations in the interstitial fluid using near IR as the interrogating medium. Copyright © 2015 Elsevier B.V. All rights reserved.

Chemometric simultaneous determination of Sofosbuvir and Ledipasvir in pharmaceutical dosage form

NASA Astrophysics Data System (ADS)

Khalili, Mahsa; Sohrabi, Mahmoud Reza; Mirzabeygi, Vahid; Torabi Ziaratgahi, Nahid

2018-04-01

Partial least squares (PLS), different families of continuous wavelet transform (CWT), and first derivative spectrophotometry (DS) techniques were studied for quantification of Sofosbuvir (SFB) and Ledipasvir (LDV) simultaneously without separation step. The components were dissolved in Acetonitrile and the spectral behaviors were evaluated in the range of 200 to 400 nm. The ultraviolet (UV) absorbance of LDV exhibits no interferences between 300 and 400 nm and it was decided to predict the LDV amount through the classic spectrophotometry (CS) method in this spectral region as well. Data matrix of concentrations and calibrated models were developed, and then by applying a validation set the accuracy and precision of each model were studied. Actual concentrations versus predicted concentrations plotted and good correlation coefficients by each method resulted. Pharmaceutical dosage form was quantified by developed methods and the results were compared with the High Performance Liquid Chromatography (HPLC) reference method. Analysis Of Variance (ANOVA) in 95% confidence level showed no significant differences among methods.

Quantitative mapping of particulate iron in an ocean dump using remotely sensed data

NASA Technical Reports Server (NTRS)

Ohlhorst, C. W.; Bahn, G. S.

1978-01-01

A remote sensing experiment was conducted at the industrial acid waste ocean dump site located approximately 38 n mi SE of Cape Henlopen, Delaware, to see if there was a relationship between aircraft remotely sensed spectral signatures and the iron concentration measured in the plume. Results are presented which show that aircraft remotely sensed spectral data can be used to quantify and map an acid waste dump in terms of its particulate iron concentration. A single variable equation using the ratio of band 2 (440-490 nm) radiance to band 4 (540-580 nm) radiance was used to quantify the acid plume and the surrounding water. The acid waste varied in age from freshly dumped to 3 1/2 hours old. Particulate iron concentrations in the acid waste were estimated to range up to 1.1 mg/liter at the 0.46 meter depth. A classification technique was developed to remove sunglitter-affected pixels from the data set.

Parametric test of a zirconium (4) oxide-polyacrylic acid dual layer hyperfiltration membrane with spacecraft washwater

NASA Technical Reports Server (NTRS)

Brandon, C. A.; Gaddis, J. L.; El-Nashar, A. M.

1975-01-01

Performance data consisting of solute rejections and product flux were measured, as dependent on the operation parameters. These parameters and ranges were pressure (500,000 n/m2 to 700,000 n/m2), temperature (74 C to 95 C), velocity (1.6 M/sec to 10 M/sec), and concentration (up to 14x). Tests were carried out on analog washwater. Data presented include rejections of organic materials, ammonia, urea, and an assortment of ions. The membrane used was deposited in situ on a porcelain ceramic substrate.

Diameter modulation of vertically aligned single-walled carbon nanotubes.

PubMed

Xiang, Rong; Einarsson, Erik; Murakami, Yoichi; Shiomi, Junichiro; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2012-08-28

We demonstrate wide-range diameter modulation of vertically aligned single-walled carbon nanotubes (SWNTs) using a wet chemistry prepared catalyst. In order to ensure compatibility to electronic applications, the current minimum mean diameter of 2 nm for vertically aligned SWNTs is challenged. The mean diameter is decreased to about 1.4 nm by reducing Co catalyst concentrations to 1/100 or by increasing Mo catalyst concentrations by five times. We also propose a novel spectral analysis method that allows one to distinguish absorbance contributions from the upper, middle, and lower parts of a nanotube array. We use this method to quantitatively characterize the slight diameter change observed along the array height. On the basis of further investigation of the array and catalyst particles, we conclude that catalyst aggregation-rather than Ostwald ripening-dominates the growth of metal particles.

An induction furnace for the determination of cadmium in solutions and zinc-base metals by atomic-absorption spectroscopy.

PubMed

Headridge, J B; Smith, D R

1971-03-01

An induction furnace coupled to a Unicam SP90 atomic-absorption spectrophotometer is described for the determination of traces of volatile elements in solutions and volatile matrices. The apparatus has been used to obtain calibration graphs for 1-20 and 50-750 ng of cadmium in microl-volumes of solution, the 228.8 and 326.2 nm resonance lines respectively being used, and to determine cadmium in 5-mg samples of zinc-base metals within the concentration range 5-400 microg g by using the less sensitive 326-2-nm line. A furnace temperature of 1,350 degrees was used. Data on accuracy and precision are presented. The apparatus could readily be used to determine trace elements in volatile materials at concentrations of 10-1000 ng/g .

C(18) columns for the simultaneous determination of oxytetracycline and its related substances by reversed-phase high performance liquid chromatography and UV detection.

PubMed

Smyrniotakis, C G; Archontaki, Helen A

2007-01-17

Simultaneous determination of oxytetracycline, 4-epioxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline on C(18) columns has been accomplished using a high performance liquid chromatographic method with UV detection. Separation was achieved on a Hypersil BDS RP-C(18) column (250 mm x 4.6 mm) and on a Waters C(18) Symmetry column (150 mm x 3.9mm), 5 microm particle size each. These columns were equilibrated with mobile phases consisted of methanol-acetonitrile-0.1M phosphate buffer pH 8.0 (12.5:12.5:75, v/v/v) and (15:15:70, v/v/v), respectively. The flow rate was 1.0 ml/min and the total elution time was 15 and 5 min, respectively. Both methods were applied to oxytetracycline raw material, human and veterinary formulations, where the excipients did not interfere. External standard calibration curves were linear for 4-epioxytetracycline, oxytetracycline, alpha-apooxytetracycline, tetracycline and beta-apooxytetracycline in the concentration range of 0.27-200 microM, 0.05-200 microM, 0.03-200 microM, 0.35-200 microM and 0.20-200 microM on column A and 0.08-200 microM, 0.15-200 microM, 0.09-200 microM, 0.25-200 microM and 0.47-200 microM on column B, respectively. Day-to-day relative standard deviation of the determination for every component was less than 3%. Concerning the first column, limits of detection and quantification of the above compounds were in the concentration ranges of 10-106 nM and 30-352 nM, respectively, whereas on the second column these ranges became 27-144 nM and 81-475 nM, respectively. Recovery of the separated compounds was 95-105%.

Confocal spectroscopic imaging measurements of depth dependent hydration dynamics in human skin in-vivo

NASA Astrophysics Data System (ADS)

Behm, P.; Hashemi, M.; Hoppe, S.; Wessel, S.; Hagens, R.; Jaspers, S.; Wenck, H.; Rübhausen, M.

2017-11-01

We present confocal spectroscopic imaging measurements applied to in-vivo studies to determine the depth dependent hydration profiles of human skin. The observed spectroscopic signal covers the spectral range from 810 nm to 2100 nm allowing to probe relevant absorption signals that can be associated with e.g. lipid and water-absorption bands. We employ a spectrally sensitive autofocus mechanism that allows an ultrafast focusing of the measurement spot on the skin and subsequently probes the evolution of the absorption bands as a function of depth. We determine the change of the water concentration in m%. The water concentration follows a sigmoidal behavior with an increase of the water content of about 70% within 5 μm in a depth of about 14 μm. We have applied our technique to study the hydration dynamics of skin before and after treatment with different concentrations of glycerol indicating that an increase of the glycerol concentration leads to an enhanced water concentration in the stratum corneum. Moreover, in contrast to traditional corneometry we have found that the application of Aluminium Chlorohydrate has no impact to the hydration of skin.

Measurements of ion concentration in gasoline and diesel engine exhaust

NASA Astrophysics Data System (ADS)

Yu, Fangqun; Lanni, Thomas; Frank, Brian P.

The nanoparticles formed in motor vehicle exhaust have received increasing attention due to their potential adverse health effects. It has been recently proposed that combustion-generated ions may play a critical role in the formation of these volatile nanoparticles. In this paper, we design an experiment to measure the total ion concentration in motor vehicle engine exhaust, and report some preliminary measurements in the exhaust of a gasoline engine (K-car) and a diesel engine (diesel generator). Under the experimental set-up reported in this study and for the specific engines used, the total ion concentration is ca. 3.3×10 6 cm -3 with almost all of the ions smaller than 3 nm in the gasoline engine exhaust, and is above 2.7×10 8 cm -3 with most of the ions larger than 3 nm in the diesel engine exhaust. This difference in the measured ion properties is interpreted as a result of the different residence times of exhaust inside the tailpipe/connecting pipe and the different concentrations of soot particles in the exhaust. The measured ion concentrations appear to be within the ranges predicted by a theoretical model describing the evolution of ions inside a pipe.

Release of ultrafine particles from three simulated building processes

NASA Astrophysics Data System (ADS)

Kumar, Prashant; Mulheron, Mike; Som, Claudia

2012-03-01

Building activities are recognised to produce coarse particulate matter but less is known about the release of airborne ultrafine particles (UFPs; those below 100 nm in diameter). For the first time, this study has investigated the release of particles in the 5-560 nm range from three simulated building activities: the crushing of concrete cubes, the demolition of old concrete slabs, and the recycling of concrete debris. A fast response differential mobility spectrometer (Cambustion DMS50) was used to measure particle number concentrations (PNC) and size distributions (PNDs) at a sampling frequency of 10 Hz in a confined laboratory room providing controlled environment and near-steady background PNCs. The sampling point was intentionally kept close to the test samples so that the release of new UFPs during these simulated processes can be quantified. Tri-modal particle size distributions were recorded for all cases, demonstrating different peak diameters in fresh nuclei (<10 nm), nucleation (10-30 nm) and accumulation (30-300 nm) modes for individual activities. The measured background size distributions showed modal peaks at about 13 and 49 nm with average background PNCs 1.47 × 104 cm-3. These background modal peaks shifted towards the larger sizes during the work periods (i.e. actual experiments) and the total PNCs increased between 2 and 17 times over the background PNCs for different activities. After adjusting for background concentrations, the net release of PNCs during cube crushing, slab demolition, and `dry' and `wet' recycling events were measured as 0.77, 19.1, 22.7 and 1.76 (×104) cm-3, respectively. The PNDs were converted into particle mass concentrations (PMCs). While majority of new PNC release was below 100 nm (i.e. UFPs), the bulk of new PMC emissions were constituted by the particles over 100 nm; 95, 79, 73 and 90% of total PNCs, and 71, 92, 93 and 91% of total PMCs, for cube crushing, slab demolition, dry recycling and wet recycling, respectively. The results of this study firmly elucidate the release of UFPs and raise a need for further detailed studies and designing health and safety related exposure guidelines for laboratory workplaces and operational building sites.

Contribution to a bio-optical model for remote sensing of Lena River water

NASA Astrophysics Data System (ADS)

Örek, H.; Doerffer, R.; Röttgers, R.; Boersma, M.; Wiltshire, K. H.

2013-11-01

Bio-optical measurements and sampling were carried out in the delta of the Lena River (northern Siberia, Russia) between 26 June and 4 July 2011. The aim of this study was to determine the inherent optical properties of the Lena water, i.e., absorption, attenuation, and scattering coefficients, during the period of maximum runoff. This aimed to contribute to the development of a bio-optical model for use as the basis for optical remote sensing of coastal water of the Arctic. In this context the absorption by CDOM (colored dissolved organic matter) and particles, and the concentrations of total suspended matter, phytoplankton-pigments, and carbon were measured. CDOM was found to be the most dominant parameter affecting the optical properties of the river, with an absorption coefficient of 4.5-5 m-1 at 442 nm, which was almost four times higher than total particle absorption values at visible wavelength range. The wavelenght-dependence of absorption of the different water constituents was chracterized by determining the semi logarithmic spectral slope. Mean CDOM, and detritus slopes were 0.0149 nm-1(standard deviation (stdev) = 0.0003, n = 18), and 0.0057 nm-1 (stdev = 0.0017, n = 19), respectively, values which are typical for water bodies with high concentrations of dissolved and particulate carbon. Mean chlorophyll a and total suspended matter were 1.8 mg m-3 (stdev = 0.734 n = 18) and 31.9 g m-3 (stdev = 19.94, n = 27), respectively. DOC (dissolved organic carbon) was in the range 8-10 g m-3 and the total particulate carbon (PC) in the range 0.25-1.5 g m-3. The light penetration depth (Secchi disc depth) was in the range 30-90 cm and was highly correlated with the suspended matter concentration. The period of maximum river runoff in June was chosen to obtain bio-optical data when maximum water constituents are transported into the Laptev Sea. However, we are aware that more data from other seasons and other years need to be collected to establish a general bio-optical model of the Lena water and conclusively characterize the light climate with respect to primary production.

Lacrimal secretion stimulants: sigma receptors and drug implications.

PubMed

Shirolkar, S; Schoenwald, R D; Barfknecht, C F; Xia, E; Cheng, B; Iwai, Y; Ignace, C C; Vidvauns, S; Newton, R E

1993-01-01

3H-DTG (1.3-di(2-[5-3H]tolyl)guanidine) or 3H-haloperidol was added to sigma-receptors (25 nM) in the presence of 25 nM spiperone and incubated with increasing concentrations of bromhexine derivatives (phenylalkylamines; 10(-9) to 10(-2)M) in membrane homogenate suspensions. IC50 values for two derivatives ranged from 3.2 to 8.8 nM for both radioligands. A preferred derivative, 7A (N,N'-dimethyl-2-phenyl-ethylamine), yielded an IC50 of 7.8 nM for 3H-haloperidol but showed much less affinity in displacing 3H-DTG (IC50 = 900 nM). Applying the technic of Bromberg [Exp. Eye Res., 40:313-320, 1985], in vitro protein secretion rates were measured following stimulation of either lacrimal gland slices or isolated, intact lacrimocytes with the compounds. In vitro protein secretion rates exhibit a dose-response relationship with increases in protein release up to a concentration of 10(-8) to 10(-4) M for various derivatives of bromhexine and 10(-4) M for carbachol. By means of Schirmer strips, tear fluid was collected over a five minute period at 10 and 60 minutes post-dosing following the topical application (50 microliters) to the right eye of New Zealand white rabbits (n = 20-24) of 7A at various concentrations. Incubation of lacrimocytes with 7A alone (10(-4) M), with haloperidol (10(-4) M) alone or in combination show that 7A is acting as an agonist to stimulate protein release, whereas haloperidol is acting as an antagonist to inhibit release. In vivo protein secretion rates also show a dose-response curve (at both 10 and 60 minutes post-dosing) for 7A that reach a statistically significant maximum in the dosed eye at a concentration of 0.15% w/v. Analysis of protein extracts using size exclusion HPLC shows an increase in secretory proteins, particularly tear-specific prealbumin.

Electro-hydrodynamic generation of monodisperse nanoparticles in the sub-10 nm size range from strongly electrolytic salt solutions: governing parameters of scaling laws

NASA Astrophysics Data System (ADS)

Maißer, Anne; Attoui, Michel B.; Gañán-Calvo, Alfonso M.; Szymanski, Wladyslaw W.

2013-01-01

A charge reduced electro-hydrodynamic atomization (EHDA) device has been used to generate airborne salt clusters in the sub 10 nm size range. The focus of this study on that specific sub-micron range of electrospray droplets with relatively high electrical conductivities and permittivities aims to address the still existing controversy on the scaling laws of electrosprayed droplet diameters. In this study different concentrations of sodium chloride and potassium chloride—both show strong electrolytic behavior—have been electrosprayed from solutions in pure water, or from aqueous ammonium acetate buffer liquids of varying concentrations. The dry residue salt cluster diameter generated by the EHDA process have been measured using a differential mobility analyzer. The initial droplet diameter has been determined indirectly from the measured particle size following the steps of Chen et al. (J Aerosol Sci 26:963-977, 1995). Results have been compared to existing scaling laws valid for direct droplet measurements. They can be interpreted concisely on the basis of a realistic hypothesis on possible electrochemical effects taking place and affecting the droplet and thus nanoparticle formation in EHDA. The hypothesis developed in this work and the comparison with the experimental results are shown and discussed in the manuscript.

Spectral changes induced by pH variation of aqueous extracts derived from biomass burning aerosols: Under dark and in presence of simulated sunlight irradiation

NASA Astrophysics Data System (ADS)

Cai, Jing; Zhi, Guorui; Yu, Zhiqiang; Nie, Peng; Gligorovski, Sasho; Zhang, Yuzhe; Zhu, Like; Guo, Xixiang; Li, Pei; He, Tan; He, Youjiang; Sun, Jianzhong; Zhang, Yang

2018-07-01

Water soluble organic carbon (WSOC) can significantly influence the aerosol optical properties and the aqueous phase chemistry in cloudwater, fogwater and aerosol liquid water. Here, we examine how the changing pH (in acidic range) affects the absorption spectra of aqueous extracts from field biomass burning aerosols, under dark conditions and in presence of simulated sunlight illumination. The observation under dark conditions indicates that pH variation from 2 to 5 induces significantly enhanced light absorbance in the wavelength ranges of 235-270 nm and 300-550 nm, whereas the light absorbance decreased in the range of 270-300 nm, which might be partially ascribed to the deprotonation of carboxylic acids and phenols. During the extract photolysis, light absorption exhibits photo-bleaching below 380 nm and photo-enhancement above 380 nm, indicating that at acidic levels (pH = 2-5), the particle extracts could undergo a significant composition evolution leading to a modification of absorptive properties. Meanwhile, after 12 h-photolysis, the acidity ([H+]) normalized by WSOC concentration in aqueous extracts ([WSOCae]) increased with a variation of Δ[H+]/[WSOCae]=(3.7 ± 0.7) × 10-7 mol mgC-1 (mean ± standard deviation), suggesting the formation of new acidic substances. Although these findings were acquired in aqueous solutions more relevant to cloud and fog water, the similar evolution likely occurs in wetted aerosols. This calls more attention to the effect of acidity on the wetted aerosols in order to better estimate the aerosol radiative forcing.

Synthetic and spectroscopic studies of vanadate glaserites II: Photoluminescence studies of Ln:K{sub 3}Y(VO{sub 4}){sub 2} (Ln=Eu, Er, Sm, Ho, or Tm)

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

Kimani, Martin M., E-mail: kimani@g.clemson.edu; McMillen, Colin D., E-mail: cmcmill@g.clemson.edu; Kolis, Joseph W., E-mail: kjoseph@clemson.edu

2015-03-15

Glaserite-type potassium yttrium double vanadates (K{sub 3}Y(VO{sub 4}){sub 2}) doped with Eu{sup 3+}, Er{sup 3+}, Sm{sup 3+}, Ho{sup 3+}, or Tm{sup 3+} have been synthesized by solid state reactions at 1000 °C for 48 h and their photoluminescence properties investigated. Efficient energy transfer from the vanadate group to the rare earth ion has been established by photoluminescence investigation. Ultraviolet excitation into the metal to ligand charge transfer band of the vanadate groups results in orange-red, blue and green emissions from Eu{sup 3+} (592 nm), Sm{sup 3+} (602 nm), Tm{sup 3+} (475 nm), Er{sup 3+} (553 nm), and Ho{sup 3+} (541–551more » nm) dopant ions. The emission intensities of the lanthanide-doped K{sub 3}Y(VO{sub 4}){sub 2} powders were studied as a function of dopant ion concentrations. Over the concentration ranges studied, no emission quenching was observed for Eu{sup 3+} or Ho{sup 3+} dopants, while Er{sup 3+}, Sm{sup 3+} and Tm{sup 3+} dopants did exhibit such effects for dopant ion concentrations greater than 5%, probably due to cross relaxation processes. - Graphical abstract: Synthesis and photoluminescence in vanadate glaserites. - Highlights: • K{sub 3}Y(VO{sub 4}){sub 2} doped with Eu, Er, Tm, Sm, or Ho were synthesized via solid-state reactions. • Photoluminescence properties are investigated. • The lanthanide doped K{sub 3}Y(VO{sub 4}){sub 2} compounds revealed efficient energy transfer from the vanadate group to the rare earth ions. • The presented compounds are promising materials for light display systems, lasers, and optoelectronic devices.« less

Clad-pumped Er-nanoparticle-doped fiber laser (Conference Presentation)

NASA Astrophysics Data System (ADS)

Baker, Colin C.; Friebele, E. Joseph; Rhonehouse, Daniel L.; Marcheschi, Barbara A.; Peele, John R.; Kim, Woohong; Sanghera, Jasbinder S.; Zhang, Jun; Chen, Youming; Pattnaik, Radha K.; Dubinskii, Mark

2017-03-01

Erbium-doped fiber lasers are attractive for directed energy weapons applications because they operate in a wavelength region that is both eye-safer and a window of high atmospheric transmission. For these applications a clad-pumped design is desirable, but the Er absorption must be high because of the areal dilution of the doped core vs. the pump cladding. High Er concentrations typically lead to Er ion clustering, resulting in quenching and upconversion. Nanoparticle (NP) doping of the core overcomes these problems by physically surrounding the Er ions with a cage of Al and O in the NP, which keeps them separated to minimize excited state energy transfer. A significant issue is obtaining high Er concentrations without the NP agglomeration that degrades the optical properties of the fiber core. We have developed the process for synthesizing stable Er-NP suspension which have been used to fabricate EDFs with Er concentrations >90 dB/m at 1532 nm. Matched clad fibers have been evaluated in a core-pumped MOPA with pump and signal wavelengths of 1475 and 1560 nm, respectively, and efficiencies of 72% with respect to absorbed pump have been obtained. We have fabricated both NP- and solution-doped double clad fibers, which have been measured in a clad-pumped laser testbed using a 1532 nm pump. The 1595 nm laser efficiency of the NP-doped fiber was 47.7%, which is high enough for what is believed to be the first laser experiment with the cladding pumped, NP-doped fiber. Further improvements are likely with a shaped cladding and new low-index polymer coatings with lower absorption in the 1500 - 1600 nm range.

The globular domain of histone H5 is internally located in the 30 nm chromatin fiber: an immunochemical study.

PubMed Central

Dimitrov, S I; Russanova, V R; Pashev, I G

1987-01-01

The location of the globular domain of histone H5 relative to the axis of the 30 nm chromatin fiber was investigated by following the accessibility of this region of the molecule in chicken erythrocyte chromatin to specific antibodies as a function of chromatin structure. Antibodies to the globular domain of H5 as well as their Fab fragments were found to react with chromatin at ionic strengths ranging from 1-80 mM NaCl, the reaction gradually decreasing upon increase of salt concentration. If, however, Fab fragments were conjugated to ferritin, no reaction of the complex with chromatin was observed at salt concentrations higher than 20 mM. The accessibility of the globular part of H5 in unfolded chromatin to the Fab-ferritin complex was also demonstrated with trypsin-digested chromatin. The experiments were carried out by both solid-phase immunoassay and inhibition experiments. The data obtained are consistent with a structure in which the globular domain of H5 is internally located in the 30 nm chromatin fiber. Images Fig. 1. Fig. 2. PMID:2444434

Determination of Cd2+ and Pb2+ Based on Mesoporous Carbon Nitride/Self-Doped Polyaniline Nanofibers and Square Wave Anodic Stripping Voltammetry

PubMed Central

Zhang, Chang; Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Zhang, Jiachao; Peng, Bo; Xie, Xia; Lai, Cui; Long, Beiqing; Zhu, Jingjing

2016-01-01

The fabrication and evaluation of a glassy carbon electrode (GCE) modified with self-doped polyaniline nanofibers (SPAN)/mesoporous carbon nitride (MCN) and bismuth for simultaneous determination of trace Cd2+ and Pb2+ by square wave anodic stripping voltammetry (SWASV) are presented here. The morphology properties of SPAN and MCN were characterized by transmission electron microscopy (TEM), and the electrochemical properties of the fabricated electrode were characterized by cyclic voltammetry (CV). Experimental parameters, such as deposition time, pulse potential, step potential, bismuth concentration and NaCl concentration, were optimized. Under the optimum conditions, the fabricated electrode exhibited linear calibration curves ranging from 5 to 80 nM for Cd2+ and Pb2+. The limits of detection (LOD) were 0.7 nM for Cd2+ and 0.2 nM for Pb2+ (S/N = 3). Additionally, the repeatability, reproducibility, anti-interference ability and application were also investigated, and the proposed electrode exhibited excellent performance. The proposed method could be extended for other heavy metal determination. PMID:28344264

Apparent Optical Properties in Waters Influenced by the Mississippi River

NASA Technical Reports Server (NTRS)

D'Sa, E.; Miller, R. L.; McKee, B. A.; Trzaska, R.

2002-01-01

In-water downwelling irradiance (E(sub d)) and upwelling radiance (L(sub u)) were measured in coastal waters influenced by the Mississippi River at wavelengths corresponding to SeaWiFS spectral bands in April of 2000. Results of derived apparent optical properties (AOP's) such as spectral diffise attenuation coefficient for downwelling irradiance (K(sub d)) suggest that they are mainly influenced by phytoplankton chlorophyll. Large variations in chlorophyll concentrations (0.2 to greater than 10 mg per cubic meters) correspond to variations in K(sub d) at 443 nm ranging from about 0.1 to greater than 1.5 per meter. Attenuation values at 443 nm generally peaked (or were minimal at 555 nm) at depths where chlorophyll concentrations were high. Above water remote sensing reflectance R(sub rs) (443) derived from E(sub d) and L(sub u) shows good agreement to surface chlorophyll. Ratios of remote sensing reflectance, R(sub rs)(443/R(sub rs)(555)versus chlorophyll suggests a potential for obtaining a suitable bio-optical algorithm for the region influenced by the Mississippi River.

Reporter Assay for Endo/Lysosomal Escape of Toxin-Based Therapeutics

PubMed Central

Gilabert-Oriol, Roger; Thakur, Mayank; von Mallinckrodt, Benedicta; Bhargava, Cheenu; Wiesner, Burkhard; Eichhorst, Jenny; Melzig, Matthias F.; Fuchs, Hendrik; Weng, Alexander

2014-01-01

Protein-based therapeutics with cytosolic targets are capable of exhibiting their therapeutic effect once they have escaped from the endosomes or lysosomes. In this study, the reporters—horseradish peroxidase (HRP), Alexa Fluor 488 (Alexa) and ricin A-chain (RTA)—were investigated for their capacity to monitor the endo/lysosomal escape of the ribosome-inactivating protein, saporin. The conjugates—saporin-HRP, Alexasaporin and saporin-KQ-RTA—were constructed, and the endo/lysosomal escape of these conjugates alone (lack of endo/lysosomal release) or in combination with certain structurally-specific triterpenoidal saponins (efficient endo/lysosomal escape) was characterized. HRP failed in reporting the endo/lysosomal escape of saporin. Contrastingly, Alexa Fluor 488 successfully allowed the report of the process at a toxin concentration of 1000 nM. In addition, single endo/lysosome analysis facilitated the determination of the amount of Alexasaporin released from each vesicle. RTA was also successful in reporting the endo/lysosomal escape of the enzymatically inactive mutant, saporin-KQ, but in this case, the sensitivity of the method reached a toxin concentration of 10 nM. In conclusion, the simultaneous usage of Alexa Fluor 488 and RTA as reporters may provide the possibility of monitoring the endo/lysosomal escape of protein-based therapeutics in the concentration range of 10–1000 nM. PMID:24859158

Multi-walled carbon nanotubes (NM401) induce ROS-mediated HPRT mutations in Chinese hamster lung fibroblasts

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

Rubio, Laura; El Yamani, Naouale; Kazimirova, Alena

Although there is an important set of data showing potential genotoxic effects of nanomaterials (NMs) at the DNA (comet assay) and chromosome (micronucleus test) levels, few studies have been conducted to analyze their potential mutagenic effects at gene level. We have determined the ability of multi-walled carbon nanotubes (MWCNT, NM401), to induce mutations in the HPRT gene in Chinese hamster lung (V79) fibroblasts. NM401, characterized in the EU NanoGenotox project, were further studied within the EU Framework Programme Seven (FP7) project NANoREG. From the proliferation assay data we selected a dose-range of 0.12 to 12 µg/cm{sup 2} At these rangemore » we have been able to observe significant cellular uptake of MWCNT by using transmission electron microscopy (TEM), as well as a concentration-dependent induction of intracellular reactive oxygen species. In addition, a clear concentration-dependent increase in the induction of HPRT mutations was also observed. Data support a potential genotoxic/ carcinogenic risk associated with MWCNT exposure. - Highlights: • MWCNT were tested in V79 cells. • Cellular uptake of MWCNT was detected using TEM. • Intracellular ROS induction was observed after MWCNT exposure. • MWCNT induced a concentration-dependent increase of HPRT mutations.« less

Evaluation and modelling of the size fractionated aerosol particle number concentration measurements nearby a major road in Helsinki - Part I: Modelling results within the LIPIKA project

NASA Astrophysics Data System (ADS)

Pohjola, M. A.; Pirjola, L.; Karppinen, A.; Härkönen, J.; Korhonen, H.; Hussein, T.; Ketzel, M.; Kukkonen, J.

2007-08-01

A field measurement campaign was conducted near a major road "Itäväylä" in an urban area in Helsinki in 17-20 February 2003. Aerosol measurements were conducted using a mobile laboratory "Sniffer" at various distances from the road, and at an urban background location. Measurements included particle size distribution in the size range of 7 nm-10 μm (aerodynamic diameter) by the Electrical Low Pressure Impactor (ELPI) and in the size range of 3-50 nm (mobility diameter) by Scanning Mobility Particle Sizer (SMPS), total number concentration of particles larger than 3 nm detected by an ultrafine condensation particle counter (UCPC), temperature, relative humidity, wind speed and direction, driving route of the mobile laboratory, and traffic density on the studied road. In this study, we have compared measured concentration data with the predictions of the road network dispersion model CAR-FMI used in combination with an aerosol process model MONO32. For model comparison purposes, one of the cases was additionally computed using the aerosol process model UHMA, combined with the CAR-FMI model. The vehicular exhaust emissions, and atmospheric dispersion and transformation of fine and ultrafine particles was evaluated within the distance scale of 200 m (corresponding to a time scale of a couple of minutes). We computed the temporal evolution of the number concentrations, size distributions and chemical compositions of various particle size classes. The atmospheric dilution rate of particles is obtained from the roadside dispersion model CAR-FMI. Considering the evolution of total number concentration, dilution was shown to be the most important process. The influence of coagulation and condensation on the number concentrations of particle size modes was found to be negligible on this distance scale. Condensation was found to affect the evolution of particle diameter in the two smallest particle modes. The assumed value of the concentration of condensable organic vapour of 1012 molecules cm-3 was shown to be in a disagreement with the measured particle size evolution, while the modelling runs with the concentration of condensable organic vapour of 109-1010 molecules cm-3 resulted in particle sizes that were closest to the measured values.

Measurements of Soot Mass Absorption Coefficients from 300 to 660 nm

NASA Astrophysics Data System (ADS)

Renbaum-Wolff, Lindsay; Fisher, Al; Helgestad, Taylor; Lambe, Andrew; Sedlacek, Arthur; Smith, Geoffrey; Cappa, Christopher; Davidovits, Paul; Onasch, Timothy; Freedman, Andrew

2016-04-01

Soot, a product of incomplete combustion, plays an important role in the earth's climate system through the absorption and scattering of solar radiation. In particular, the assumed mass absorption coefficient (MAC) of soot and its variation with wavelength presents a significant uncertainty in the calculation of radiative forcing in global climate change models. As part of the fourth Boston College/Aerodyne soot properties measurement campaign, we have measured the mass absorption coefficient of soot produced by an inverted methane diffusion flame over a spectral range of 300-660 nm using a variety of optical absorption techniques. Extinction and absorption were measured using a dual cavity ringdown photoacoustic spectrometer (CRD-PAS, UC Davis) at 405 nm and 532 nm. Scattering and extinction were measured using a CAPS PMssa single scattering albedo monitor (Aerodyne) at 630 nm; the absorption coefficient was determined by subtraction. In addition, the absorption coefficients in 8 wavelength bands from 300 to 660 nm were measured using a new broadband photoacoustic absorption monitor (UGA). Soot particle mass was quantified using a centrifugal particle mass analyzer (CPMA, Cambustion), mobility size with a scanning mobility particle sizer (SMPS, TSI) and soot concentration with a CPC (Brechtel). The contribution of doubly charged particles to the sample mass was determined using a Single Particle Soot Photometer (DMT). Over a mass range of 1-8 fg, corresponding to differential mobility diameters of ~150 nm to 550 nm, the value of the soot MAC proved to be independent of mass for all wavelengths. The wavelength dependence of the MAC was best fit to a power law with an Absorption Ångstrom Coefficient slightly greater than 1.

Do bupivacaine, clindamycin, and gentamicin at their clinical concentrations enhance rocuronium-induced neuromuscular block?

PubMed Central

Lee, Ji Hyeon; Park, Sang Yoong; Park, Jae-Won

2013-01-01

Background Bupivacaine, clindamycin, and gentamicin inhibit neuromuscular (NM) conduction. When they are combined, they may synergistically reduce the effective concentration of each to the therapeutic concentration in augmenting rocuronium-induced NM block. Thus, the aim of this study was to investigate whether combinations of the three drugs, at around their therapeutic concentrations, potentiate rocuronium-induced NM block. Methods Fifty-seven left-phrenic nerve hemidiaphragms (Male S-D rats, 150-250 g) were hung in a 20-ml organ bath filled with Krebs solution. Three consecutive single-twitch tensions (0.1 Hz) and one tetanic tension (50 Hz for 1.9 s) were obtained. A Krebs solution was premixed with concentration sets of bupivacaine and clindamycin, bupivacaine and gentamicin, or bupivacaine, clindamycin and gentamicin. Then, the concentration of rocuronium was cumulatively increased in the Krebs solution (1, 3, 5, 7, 9, 12, 14, 16, 18, and 20 µM) until an 80% to 90% reduction in single twitch was attained. The effective concentrations for each experiment were determined with the probit model. Results The combinations of bupivacaine, clindamycin, and gentamicin enhanced rocuronium-induced NM block. When the three drugs were applied simultaneously, their concentrations were reduced to near-therapeutic levels in potentiating the action of rocuronium. Conclusions Bupivacaine, clindamycin, and gentamicin blocked NM conduction, and when all three drugs were applied together, they augmented rocuronium-induced NM block at their near-therapeutic concentrations. Clinicians should be aware of the cooperability in NM block between drugs that interrupt NM conduction. PMID:23646245

Nanoassembled thin film gas sensors. III. Sensitive detection of amine odors using TiO2/poly(acrylic acid) ultrathin film quartz crystal microbalance sensors.

PubMed

Lee, Seung-Woo; Takahara, Naoki; Korposh, Sergiy; Yang, Do-Hyeon; Toko, Kiyoshi; Kunitake, Toyoki

2010-03-15

Quartz crystal microbalance (QCM) gas sensors based on the alternate adsorption of TiO(2) and polyacrilic acid (PAA) were developed for the sensitive detection of amine odors. Individual TiO(2) gel layers could be regularly assembled with a thickness of approximately 0.3 nm by the gas-phase surface sol-gel process (GSSG). The thickness of the poly(acrylic acid) (PAA) layer is dependent on its molecular weight, showing different thicknesses of approximately 0.4 nm for PAA(25) (Mw 250,000) and 0.6-0.8 nm for PAA(400) (Mw 4,000,000). The QCM sensors showed a linear response to ammonia in the concentration range 0.3-15 ppm, depending on the deposition cycle of the alternate TiO(2)/PAA layer. The ammonia binding is based on the acid-base interaction to the free carboxylic acid groups of PAA and the limit of detection (LOD) of the 20-cycle TiO(2)/PAA(400) film was estimated to be 0.1 ppm when exposed to ammonia. The sensor response was very fast and stable in a wide relative humidity (rH) range of 30-70%, showing almost the same frequency changes at a given concentration of ammonia. Sensitivity to n-butylamine and ammonia was higher than to pyridine, which is owing to the difference of molecular weight and basicity of the amine analytes. The alternate TiO(2)/PAA(400) films have a highly effective ability to capture amine odors, and the ambient ammonia concentration of 15 ppm could be condensed up to approximately 20,000 ppm inside the films.

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

Chen, Peican; Zhou, Liya, E-mail: zhouliyatf@163.com; Mo, Fuwang

Graphical abstract: - Highlights: • Novel Eu{sup 2+} doped Sr{sub 6}Ca{sub 4}(PO{sub 4}){sub 6}F{sub 2} phosphors was synthesized for the first time. • The Sr{sub 6}Ca{sub 4}(PO{sub 4}){sub 6}F{sub 2}:Eu{sup 2+} phosphors produced blue light when irradiated at 368 nm. • The emission band of the sample could be decomposed into two Gaussian profiles. - Abstract: For the first time, a series of novel blue light-emitting phosphors Sr{sub 6}Ca{sub 4}(PO{sub 4}){sub 6}F{sub 2}:Eu{sup 2+} were synthesized by a traditional solid-state reaction. The phosphors exhibited a broad and intense excitation band that could be pumped by near ultraviolet to exhibit amore » broad photoluminescence band ranging from 400 nm to 530 nm peaking at 452 nm. Quenching concentration was 0.05 mol. Furthermore, the mechanism of concentration quenching involving SCPF:Eu{sup 2+} was demonstrated to be a dipole–dipole interaction with critical distance of 27.95 Å. Decay time curves were also measured to validate energy transfer, and quantum efficiency is investigated. The chromaticity diagram of Commission Internationale de l’Eclairage indicated that SCPF:Eu{sup 2+} may be used as a blue-emitting component for white light-emitting diode applications.« less

Near-infrared spectral methods for noninvasively measuring blood glucose

NASA Astrophysics Data System (ADS)

Fei, Sun; Kong, Deyi; Mei, Tao; Tao, Yongchun

2004-05-01

Determination of blood glucose concentrations in diabetic patients is a frequently occurring procedure and an important tool for diabetes management. Use of noninvasive detection techniques can relieve patients from the pain of frequent finger pokes and avoid the infection of disease via blood. This thesis discusses current research and analyzes the advantages and shortages of different measurement methods, including: optical methods (Transmission, Polarimetry and scattering), then, we give emphasis to analyze the technology of near-infrared (NIR) spectra. NIR spectral range 700 nm ~2300 nm was used because of its good transparency for biological tissue and presence of glucose absorption band. In this work, we present an outline of noninvasive blood glucose measurement. A near-infrared light beam is passed through the finger, and the spectral components of the emergent beam are measured using spectroscopic techniques. The device includes light sources having the wavelengths of 600 nm - 1800 nm to illuminate the tissue. Receptors associated with the light sources for receiving light and generating a transmission signal representing the light transmitted are also provided. Once a transmission signal is received by receptors, and the high and low values from each of the signals are stored in the device. The averaged values are then analyzed to determine the glucose concentration, which is displayed on the device.

Optical characterization of nanoporous AAO sensor substrate

NASA Astrophysics Data System (ADS)

Kassu, Aschalew; Farley, Carlton W.; Sharma, Anup

2014-05-01

Nanoporous anodic aluminum oxide (AAO) has been investigated as an ideal and cost-effective chemical and biosensing platform. In this paper, we report the optical properties of periodic 100 micron thick nanoporous anodic alumina membranes with uniform and high density cylindrical pores penetrating the entire thickness of the substrate, ranging in size from 18 nm to 150 nm in diameter and pore periods from 44 nm to 243 nm. The surface geometry of the top and bottom surface of each membrane is studied using atomic force microscopy. The optical properties including transmittance, reflectance, and absorbance spectra on both sides of each substrate are studied and found to be symmetrical. It is observed that, as the pore size increases, the peak resonance intensity in transmittance decreases and in absorbance increases. The effects of the pore sizes on the optical properties of the bare nanoporous membranes and the benefit of using arrays of nanohole arrays with varying hole size and periodicity as a chemical sensing platform is also discussed. To characterize the optical sensing technique, transmittance and reflectance measurements of various concentrations of a standard chemical adsorbed on the bare nanoporous substrates are investigated. The preliminary results presented here show variation in transmittance and reflectance spectra with the concentration of the chemical used or the amount of the material adsorbed on the surface of the substrate.

Fungus-mediated synthesis of gold nanoparticles and standardization of parameters for its biosynthesis.

PubMed

Tidke, Pritish R; Gupta, Indarchand; Gade, Aniket K; Rai, Mahendra

2014-12-01

We report the extracellular biosynthesis of gold nanoparticles (AuNPs) using a fungus Fusarium acuminatum. Mycosynthesis of Au-NPs was carried out by challenging the fungal cells filtrate with HAuCl 4 solution (1 mM), as nanoparticles synthesizing enzyme secrete extracellularly by the fungi. The AuNPs were characterized with the help of UV-Visible spectrophotometer, Fourier Transform Infrared spectroscopy, Zeta Potential, X-ray diffraction (XRD) and Transmission electron microscopy (TEM). We observed absorbance peak in between 520 nm-550 nm corresponding to the surface plasmon absorbance of the gold nanoparticles. The nanoparticles synthesized in the present investigation were found to be capped by proteins. XRD results showed that the distinctive formation of crystalline gold nanoparticles in the solution. The spherical and polydispersed AuNPs in the range 8 to 28 nm with average size of 17 nm were observed by TEM analysis. We also standardized the parameters like the effect of pH, temperature and salt concentration on the biosynthesis of gold nanoparticles. It was found that acidic pH, 1 mM salt concentration and 37 (°)C temperature were found to be optimum for the synthesis of Au-NPs. Therefore, the present study introduces the easy, better and cheaper method for biosynthesis of AuNPs.

Spectral properties of the association nanoparticle system of ciprofloxacin-phloxine and its application to fluorescence analysis.

PubMed

Zou, Jieming; Jiang, Zhiliang; Wang, Lisheng; Li, Tingsheng; Liu, Qinye

2004-06-01

There is a fluorescence peak at 570 nm, and a maximum absorption peak at 560 nm for phloxine (PHLO) in a pH 7 water solution. Under these conditions, the ciprofloxacin cation (CPFX+) and PHLO- combine into hydrophobic CPFX-PHLO association molecule by means of static gravitation. There are stronger van der Waals forces and hydrophobic forces among the CPFX-PHLO molecules. Thus, they aggregate automatically to the (CPFX-PHLO)n association nanoparticle in red-violet color. That was characterized by scan electron microscopy (SEM), hyperfiltration and dialysis tests. In 0.04 M HCl, the red-violet nanoparticles exhibited a Rayleigh scattering peak at 470 nm, a resonance scattering peak at 580 nm, a maximum absorption wavelength at 565 nm, and a fluorescence peak at 450 nm. The fluorescence analytical conditions of CPFX have been considered. The CPFX concentration in the range of 1.0 x 10(-6)-4.0 x 10(-5) M is linear to the fluorescence intensity, F450nm. The detection limit was achieved at 4.0 x 10(-7) M CPFX. The CPFX in real samples was determined with satisfactory results.

Broadband reflection of polymer-stabilized chiral nematic liquid crystals induced by a chiral azobenzene compound.

PubMed

Chen, Xingwu; Wang, Ling; Chen, Yinjie; Li, Chenyue; Hou, Guoyan; Liu, Xin; Zhang, Xiaoguang; He, Wanli; Yang, Huai

2014-01-21

A chiral nematic liquid crystal-photopolymerizable monomer-chiral azobenzene compound composite was prepared and then polymerized under UV irradiation. The reflection wavelength of the composite can be extended to cover the 1000-2400 nm range and also be adjusted to the visible light region by controlling the concentration of chiral compounds.

Excitation wavelength selection for quantitative analysis of carotenoids in tomatoes using Raman spectroscopy.

PubMed

Hara, Risa; Ishigaki, Mika; Kitahama, Yasutaka; Ozaki, Yukihiro; Genkawa, Takuma

2018-08-30

The difference in Raman spectra for different excitation wavelengths (532 nm, 785 nm, and 1064 nm) was investigated to identify an appropriate wavelength for the quantitative analysis of carotenoids in tomatoes. For the 532 nm-excited Raman spectra, the intensity of the peak assigned to the carotenoid has no correlation with carotenoid concentration, and the peak shift reflects carotenoid composition changing from lycopene to β-carotene and lutein. Thus, 532 nm-excited Raman spectra are useful for the qualitative analysis of carotenoids. For the 785 nm- and 1064 nm-excited Raman spectra, the peak intensity of the carotenoid showed good correlation with carotenoid concentration; thus, regression models for carotenoid concentration were developed using these Raman spectra and partial least squares regression. A regression model designed using the 785 nm-excited Raman spectra showed a better result than the 532 nm- and 1064 nm-excited Raman spectra. Therefore, it can be concluded that 785 nm is the most suitable excitation wavelength for the quantitative analysis of carotenoid concentration in tomatoes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Analysis of albumin Raman scattering in visible and near-infrared ranges

NASA Astrophysics Data System (ADS)

Lykina, Anastasia A.; Artemyev, Dmitry N.

2018-04-01

In this work the analysis of the shape and intensity of albumin Raman signals in visible and near-IR ranges was carried out. The experimental setup using lasers from the visible region first of all excites the fluorescence of the albumin solution, the main contribution to which is produced by sodium chloride, which is a component of the tested sample. At the same time, lasers from the near-infrared range excited the Raman signal of albumin most effectively. It was found that the highest ratio of Raman scattering to autofluorescence intensities in the detected signal was obtained using a laser with a wavelength of 1064 nm. To determine the albumin solution concentration by type of spectrum, a regression approach with the projection to latent structures method was applied. The lowest predicted error of albumin concentration of 2-3 g/l was obtained by using the near-infrared range lasers.

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

Pathak, A. A., E-mail: anuapathak@yahoo.com; Yadav, P. J.; Talewar, R. A.

Blue-emitting phosphor LaMgAl{sub 11}O{sub 19}:Eu{sup 2+} has been synthesized successfully at 500 °C by one step combustion synthesis method. The as-synthesized materials were characterized by powder x-ray diffraction (XRD) and photoluminescence (PL) techniques. Upon 365 nm excitation, emission spectra of the LaMgAl{sub 11}O{sub 19}:Eu{sup 2+} phosphors show a blue band at 450 nm. The excitation spectra corresponding to 4f{sup 7}-4f{sup 6}5d transition of Eu{sup 2+} cover the spectral range of 280–430 nm. The concentration quenching of Eu{sup 2+} in the LaMgAl{sub 11}O{sub 19} host was determined to be 3 mol%. The CIE chromaticity of LAM: Eu{sup 2+} phosphors was compared with the commercial BAM.

Modification of fluorescence and optical properties of Rhodamine B dye doped PVA/Chitosan polymer blend films

NASA Astrophysics Data System (ADS)

Padmakumari, R.; Ravindrachary, V.; Mahantesha, B. K.; Sagar, Rohan N.; Sahanakumari, R.; Bhajantri, R. F.

2018-05-01

Pure and Rhodamine B doped Poly (vinyl alcohol)/Chitosan composite films are prepared using solution casting method. Fourier transforms infrared spectra (FTIR), Ultraviolet-Visible (UV-Vis), fluorescence studies were used to characterize the prepared polymer films. The FT-IR results show that the appearance of new peaks along with shift in peak positions indicates the interaction of Rhodamine B with PVA-CS blend. Optical absorption edge, band gap and activation energy were determined from UV-Visible studies. The optical absorption edge increases, band gap decreases and activation energy increases with dopant concentration respectively. The corresponding emission spectra were studied using fluorescence spectroscopy. From the fluorescence study the quenching phenomena are observed in emission wavelength range of 607nm-613nm upon excitation with absorption maxima 443nm.

A new and simple resonance Rayleigh scattering method for human serum albumin using graphite oxide as probe.

PubMed

Wang, Shengmian; Xu, Lili; Wang, Lisheng; Liang, Aihui; Jiang, Zhiliang

2013-01-01

Graphite oxide (GO) was prepared by the Hummer procedure, and can be dispersed to stable colloid solution by ultrasonic wave. The GO exhibited an absorption peak at 313 nm, and a resonance Rayleigh scattering (RRS) peak at 490 nm. In pH 4.6 HAc-NaAc buffer solution, human serum albumin (HSA) combined with GO probe to form large HSA-GO particles that caused the RRS peak increasing at 490 nm. The increased RRS intensity was linear to HSA concentration in the range 0.50-200 µg/mL. Thus, a new and simple RRS method was proposed for the determination of HSA in samples, with a recovery of 98.1-104%. Copyright © 2012 John Wiley & Sons, Ltd.

Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

NASA Astrophysics Data System (ADS)

Maity, Anupam; Panda, Sovan Kumar

2018-04-01

Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

Thermoluminescent properties of ZnS:Mn nanocrystalline powders.

PubMed

Ortiz-Hernández, Arturo Agustín; Méndez García, Víctor Hugo; Pérez Arrieta, María Leticia; Ortega Sígala, José Juan; Araiza Ibarra, José de Jesús; Vega-Carrillo, Héctor Rene; Falcony Guajardo, Ciro

2015-05-01

Thermoluminescent ZnS nanocrystals doped with Mn(2+) ions were synthesized by chemical co-precipitation method. From X-ray diffraction studies it was observed that the synthesized nanoparticles have cubic zinc blende structure with average sizes of about 40-50nm. Morphology was analyzed by TEM. Photoluminescence studies showed two transitions, one of them close to 396nm and other close to 598nm, which is enhanced with increasing dopant concentration, this behavior was also observed in the cathodoluminescence spectrum. The thermoluminescence gamma dose-response has linear behavior over dose range 5-100mGy, the glow curve structure shows two glow peaks at 436K and at 518K that were taken into account to calculate the kinetic parameters using the Computerized Glow Curve Deconvolution procedure. Copyright © 2015 Elsevier Ltd. All rights reserved.

A spectrophotometric determination of cyanate using reaction with 2-aminobenzoic acid.

PubMed

Guilloton, M; Karst, F

1985-09-01

A specific method has been devised for the assay of cyanate, based on the reaction with 2-aminobenzoic acid. Cyclization of the product in 6 N HCl results in the formation of 2,4(1H,3H)-quinazolinedione. Cyanate content of the samples can be measured by their absorbances at 310 nm. Alternatively, the second derivatives of the spectra can be recorded; the peak-to-peak height between the first maximum (330 nm) and the first minimum (317 nm) was shown to be proportional to the cyanate content. This method is suitable for the estimation of cyanate in aqueous solutions in the concentration range 0.01 to 2 mM. When added to blood plasma, cyanate could be detected down to 0.1 mM.

A laboratory study of particulate and gaseous emissions from crude oil and crude oil-dispersant contaminated seawater due to breaking waves

NASA Astrophysics Data System (ADS)

Afshar-Mohajer, Nima; Li, Cheng; Rule, Ana M.; Katz, Joseph; Koehler, Kirsten

2018-04-01

Crude oil spill incidents occur frequently causing a verity of occupational, ecological and environmental problems. Dispersants are applied to enhance the dispersion rate of crude oil slicks into the water column. In this study, the aerosol size distribution from 10 nm to 20 μm, total particle-bound aromatic hydrocarbons (pPAH) and volatile organic compounds (VOCs) are measured in a 6 x 0.3 x 0.6 m tank as plunging breaking waves entrain oil slicks. The experiments are performed for seawater with slicks of crude oil, crude oil-dispersant mixture and dispersant only. The measurements investigate the effects of wave energy and slick properties on the temporal evolution of the emissions. The total number concentrations of particles originating from the oil-dispersant mixture are 1-2 orders of magnitude higher than those of crude oil across the entire nano-scale range, reaching 100x for 20 nm particles. Conversely, the differences in concentration are small in the micron range. The average concentrations of pPAH are variable but similar (150-270 ng/m3). The VOC concentrations for crude oil-dispersant mixtures are 2-3 times lower than those of crude oil, presumably due to the surfactant effect on mass diffusion. The drastic increase in ultrafine particle concentrations may raise concerns about effects of inhalation by cleanup workers and downstream communities though VOC emissions reduce. Findings through this study provide insight into how the spray of dispersant may change the ratio of airborne particulate matter and VOC emissions from seawater due to natural processes.

Modafinil in Forensic and Clinical Toxicology-Case Reports, Analytics and Literature.

PubMed

Radünz, Lars; Reuter, Hannah; Andresen-Streichert, Hilke

2018-06-01

Modafinil is used because of its wakefulness-promoting properties for treatment of diseases associated with extreme sleepiness (i.e., narcolepsy). Additionally, it is misused as a "cognitive enhancer" to increase alertness and to improve concentration. We present modafinil concentrations in serum samples in five cases of our routine work measured by high-performance liquid chromatography coupled with a photo diode array detector after solid-phase extraction. One sample was analyzed for clinical toxicology purposes. The other four were investigated for the police: three cases of driving under the influence of drugs and one case of bodily harm. Sample preparation consisted of solid-phase extraction using Bond Elut® C18 columns. Papaverine was used as internal standard. Chromatographic separation was carried out using a Polaris C18-A column in an isocratic run. Wavelengths used for UV-detection were 220 nm for modafinil and 239 nm for the internal standard, respectively. The method was validated with a reduced validation design for rare analytes. A six-point-calibration from 0.5 to 5.0 mg/L, covering the therapeutic range (0.9-3.3 mg/L), was used for quantification. Concentrations in serum were in the range of 1.3 to ~34 mg/L (median: 3.6 mg/L; mean: 9.0 mg/L). To our knowledge, there are only few publications concerning the serum concentrations of modafinil in cases of (suspected) misuse, forensic cases or intoxications. In our discussion, the serum concentrations we determined are compared with the levels described in the literature so far.

Luminescence and Luminescence Quenching of K2Bi(PO4)(MoO4):Eu3+ Phosphors with Efficiencies Close to Unity.

PubMed

Grigorjevaite, Julija; Katelnikovas, Arturas

2016-11-23

A very good light emitting diode (LED) phosphor must have strong absorption, high quantum efficiency, high color purity, and high quenching temperature. Our synthesized K 2 Bi(PO 4 )(MoO 4 ):Eu 3+ phosphors possess all of the mentioned properties. The excitation of these phosphors with the near-UV or blue radiation results in a bright red luminescence dominated by the 5 D 0 → 7 F 2 transition at ∼615 nm. Color coordinates are very stable when changing Eu 3+ concentration or temperature in the range of 77-500 K. Furthermore, samples doped with 50% and 75% Eu 3+ showed quantum efficiencies close to 100% which is a huge benefit for practical application. Temperature dependent luminescence measurements showed that phosphor performance increases with increasing Eu 3+ concentration. K 2 Eu(PO 4 )(MoO 4 ) sample at 400 K lost only 20% of the initial intensity at 77 K and would lose half of the intensity only at 578 K. Besides, the ceramic disks with thicknesses of 0.33 and 0.89 mm were prepared from K 2 Eu(PO 4 )(MoO 4 ) powder, and it turned out that they efficiently converted the radiation of 375 nm LED to the red light. The conversion of 400 nm LED radiation to the red light was not complete; thus, the light sources with various tints of purple color were obtained. The combination of ceramic disks with 455 nm LED yielded the light sources with tints of blue color due to the low absorption of ceramic disk in this spectral range. In addition, these phosphors possess a very unique emission spectra; thus, they could also be applied in luminescent security pigments.

Determination of mercury (II) ions based on silver-nanoparticles-assisted growth of gold nanostructures: UV-Vis and surface enhanced Raman scattering approaches

NASA Astrophysics Data System (ADS)

Chen, Jun-Liang; Yang, Pei-Chia; Wu, Tsunghsueh; Lin, Yang-Wei

2018-06-01

Innovative dual detection methods for mercury(II) ions (Hg(II)) have been developed based on the formation of gold nanostructures (AuNSs) following the addition of mercury-containing solution to a mixture containing an optimized amount of Au(III), H2O2, HCl, and silver nanoparticles (AgNPs). In the absence of Hg(II), the addition of Au(III), H2O2, and HCl to the AgNP solution changes the solution's color from yellow to red, and the absorption peak shifts from 400 to 526 nm, indicating the dissolution of AgNPs and the formation of gold nanoparticles (AuNPs). Because of the spontaneous redox reaction of Hg(II) toward AgNPs, the change in the amount of remaining AgNP seed facilitates the generation of irregular AuNSs, resulting in changes in absorption intensity and shifting the peak within the range from 526 to 562 nm depending on the concentration of Hg(II). Under optimal conditions, the limit of detection (LOD) for Hg(II) at a signal-to-noise ratio (S/N) of 3 was 0.3 μM. We further observed that AgNP-assisted catalytic formation of Au nanomaterials deposited on a surface enhanced Raman scattering active substrate significantly reduced the Raman signal of 4-mercaptobenzoic acid, dependent on the Hg(II) concentration. A linear relationship was observed in the range 0.1 nM-100 μM with a LOD of 0.05 nM (S/N 3.0). As a simple, accurate and precise method, this SERS-based assay has demonstrated its success in determining levels of Hg(II) in real water samples.

Validation of LIRIC aerosol concentration retrievals using airborne measurements during a biomass burning episode over Athens

NASA Astrophysics Data System (ADS)

Kokkalis, Panagiotis; Amiridis, Vassilis; Allan, James D.; Papayannis, Alexandros; Solomos, Stavros; Binietoglou, Ioannis; Bougiatioti, Aikaterini; Tsekeri, Alexandra; Nenes, Athanasios; Rosenberg, Philip D.; Marenco, Franco; Marinou, Eleni; Vasilescu, Jeni; Nicolae, Doina; Coe, Hugh; Bacak, Asan; Chaikovsky, Anatoli

2017-01-01

In this paper we validate the Lidar-Radiometer Inversion Code (LIRIC) retrievals of the aerosol concentration in the fine mode, using the airborne aerosol chemical composition dataset obtained over the Greater Athens Area (GAA) in Greece, during the ACEMED campaign. The study focuses on the 2nd of September 2011, when a long-range transported smoke layer was observed in the free troposphere over Greece, in the height range from 2 to 3 km. CIMEL sun-photometric measurements revealed high AOD ( 0.4 at 532 nm) and Ångström exponent values ( 1.7 at 440/870 nm), in agreement with coincident ground-based lidar observations. Airborne chemical composition measurements performed over the GAA, revealed increased CO volume concentration ( 110 ppbv), with 57% sulphate dominance in the PM1 fraction. For this case, we compare LIRIC retrievals of the aerosol concentration in the fine mode with the airborne Aerosol Mass Spectrometer (AMS) and Passive Cavity Aerosol Spectrometer Probe (PCASP) measurements. Our analysis shows that the remote sensing retrievals are in a good agreement with the measured airborne in-situ data from 2 to 4 km. The discrepancies observed between LIRIC and airborne measurements at the lower troposphere (below 2 km), could be explained by the spatial and temporal variability of the aerosol load within the area where the airborne data were averaged along with the different time windows of the retrievals.

Relationship between sensitizer concentration and resist performance of chemically amplified extreme ultraviolet resists in sub-10 nm half-pitch resolution region

NASA Astrophysics Data System (ADS)

Kozawa, Takahiro; Santillan, Julius Joseph; Itani, Toshiro

2017-01-01

The development of lithography processes with sub-10 nm resolution is challenging. Stochastic phenomena such as line width roughness (LWR) are significant problems. In this study, the feasibility of sub-10 nm fabrication using chemically amplified extreme ultraviolet resists with photodecomposable quenchers was investigated from the viewpoint of the suppression of LWR. The relationship between sensitizer concentration (the sum of acid generator and photodecomposable quencher concentrations) and resist performance was clarified, using the simulation based on the sensitization and reaction mechanisms of chemically amplified resists. For the total sensitizer concentration of 0.5 nm-3 and the effective reaction radius for the deprotection of 0.1 nm, the reachable half-pitch while maintaining 10% critical dimension (CD) LWR was 11 nm. The reachable half-pitch was 7 nm for 20% CD LWR. The increase in the effective reaction radius is required to realize the sub-10 nm fabrication with 10% CD LWR.

A dual spectroscopic fluorescence probe based on carbon dots for detection of 2,4,6-trinitrophenol/Fe (III) ion by fluorescence and frequency doubling scattering spectra and its analytical applications.

PubMed

Xu, Jinxia; Bai, Zhangjun; Zu, Fanlin; Yan, Fanyong; Wei, Junfu; Zhang, Saihui; Luo, Yunmei

2018-07-05

A convenient, highly sensitive and reliable assay for 2,4,6‑trinitrophenol (TNP) and Fe (III) ion (Fe 3+ ) in the dual spectroscopic manner is developed based on novel carbon dots (CDs). The CDs with highly blue emitting fluorescent were easily prepared via the one-step potassium hydroxide-assisted reflux method from dextrin. The as-synthesized CDs exhibited the high crystalline quality, the excellent fluorescence characteristics with a high quantum yield of ~13.1%, and the narrow size distribution with an average diameter of 6.3±0.5nm. Fluorescence and frequency doubling scattering (FDS) spectra of CDs show the unique changes in the presence of TNP/Fe 3+ by different mechanism. The fluorescence of CDs decreased apparently in the presence of TNP via electron-transfer. Thus, after the experimental conditions were optimized, the linear range for detection TNP is 0-50μM, the detection limit was 19.1nM. With the addition of Fe 3+ , the FDS of CDs appeared to be highly sensitive with a quick response to Fe 3+ as a result of the change concentration of the scattering particle. The emission peak for FDS at 450nm was enhanced under the excitation wavelength at 900nm. The fluorescence response changes linearly with Fe 3+ concentration in the range of 8-40μM, the detection limits were determined to be 44.1nM. The applications of CDs were extended for the detection of TNP, Fe 3+ in real water samples with a high recovery. The results reported here may become the potential tools for the fast response of TNP and Fe 3+ in the analysis of environmental pollutants. Copyright © 2018 Elsevier B.V. All rights reserved.

Sol–gel synthesis, structure and luminescence properties of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors

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

Li, Yuntong; Liu, Xiaohua, E-mail: xhliuxhliu@tom.com

2015-04-15

Graphical abstract: The phosphor powders of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} were prepared by sol–gel method. The dependence of luminescence intensity on the Eu{sup 3+} concentration was investigated. - Highlights: • We synthesize Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors by the sol–gel method. • The effect of temperature on the crystallinity and morphology is investigated. • The phosphor presents an intense CT band in near UV range (370–410 nm). • The concentration quenching mechanism is the exchange interaction. - Abstract: Double-perovskite Ba{sub 2}Zn{sub 1−x}MoO{sub 6}:xEu{sup 3+} (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) orange–red emitting phosphors were synthesized by using themore » sol–gel method. The crystalline structure and photoluminescence properties of the phosphors were investigated. The X-ray diffraction (XRD) patterns indicate that the structure of matrix Ba{sub 2}ZnMoO{sub 6} is cubic double-perovskite with space group Fm-3m. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors present an intense broad charge transfer (CT) band absorption in near UV range (370–410 nm), which attributes to the charge transfer state of MoO{sub 6}, and performs orange–red emission of Eu{sup 3+} ({sup 5}D{sub 0} → {sup 7}F{sub 1} transition) at around 596 nm. A low concentration quenching occurs in Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} and the optimal doping concentration is about 6 mol%. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors are considered to be a promising orange–red emitting phosphor for near ultraviolet GaN-based white light emitting diode.« less

Personal exposure to ultrafine particles from PVC welding and concrete work during tunnel rehabilitation.

PubMed

Jørgensen, Rikke Bramming; Buhagen, Morten; Føreland, Solveig

2016-07-01

To investigate the exposure to number concentration of ultrafine particles and the size distribution in the breathing zone of workers during rehabilitation of a subsea tunnel. Personal exposure was measured using a TSI 3091 Fast Mobility Particle Sizer (FMPS), measuring the number concentration of submicrometre particles (including ultrafine particles) and the particle size distribution in the size range 5.6-560 nm. The measurements were performed in the breathing zone of the operators by the use of a conductive silicone tubing. Working tasks studied were operation of the slipforming machine, operations related to finishing the verge, and welding the PVC membrane. In addition, background levels were measured. Arithmetic mean values of ultrafine particles were in the range 6.26×10(5)-3.34×10(6). Vertical PVC welding gave the highest exposure. Horizontal welding was the work task with the highest maximum peak exposure, 8.1×10(7) particles/cm(3). Background concentrations of 4.0×10(4)-3.1×10(5) were found in the tunnel. The mobility diameter at peak particle concentration varied between 10.8 nm during horizontal PVC welding and during breaks and 60.4 nm while finishing the verge. PVC welding in a vertical position resulted in very high exposure of the worker to ultrafine particles compared to other types of work tasks. In evaluations of worker exposure to ultrafine particles, it seems important to distinguish between personal samples taken in the breathing zone of the worker and more stationary work area measurements. There is a need for a portable particle-sizing instrument for measurements of ultrafine particles in working environments. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Source region and sector contributions of atmospheric soot particle in a coalfield region of Dhanbad, eastern part of India

NASA Astrophysics Data System (ADS)

Singh, S.; Tiwari, S.; Dumka, U. C.; Kumar, R.; Singh, P. K.

2017-11-01

Black carbon (BC) aerosols affect the Earth's climate directly by interacting with the solar radiation and indirectly by modifying the lifetime and optical properties of clouds. However, our understanding of BC aerosols and their impacts on the climate are limited by lack of in situ measurements of BC, especially in the developing world. This study reports measurements of BC from Dhanbad, a coalfields area of eastern India, we analyze BC data at 370 and 880 nm during 2013 to gain insight into the emission sources affecting the study area. Our analysis indicates significantly higher absorption at the lower wavelength (ultraviolet). We estimate that 33% of BC at Dhanbad comes from biomass/biofuel combustion and the remaining 67% from the fossil fuel combustion. Higher concentrations of BC370 nm (> 12 μg m- 3) were observed when the air masses affecting Dhanbad originated far away in countries like Iran, Afghanistan, Pakistan, Oman, United Arab Emirates and passed over the Indo-Gangetic Plains (IGP) prior to arriving at the observation site. The source regions affecting BC880 nm were localized over the IGP but BC880 nm concentrations are 33% lower ( 8 μg m- 3) than BC370 nm. The cluster analysis showed that the largest fraction (35 and 29%) of the air masses arriving at Dhanbad passed through the boundary layer of the central IGP and north-west IGP region during the post-monsoon season. Average values of BC370 nm (16.0 and 20.0 μg m- 3) and BC880 nm (9.5 and 10.0 μg m- 3) in the IGP influenced air masses were significantly higher than those arriving from other source regions. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) model were applied to understand the relative importance of different sources affecting Dhanbad. The variability of observed BC mass concentrations was captured fairly well by WRF-Chem with minor deviations from the measured values. Model results indicate that anthropogenic emissions account for more than 75% of the surface BC at Dhanbad. Biomass burning contribution peaks in March-April and October-November but remains less than 25%. Long-range transport estimated in terms of inflow from domain boundaries does not affect BC concentrations at Dhanbad significantly.

Comparative estrogenicity of endogenous, environmental and dietary estrogens in pregnant women I: Serum levels, variability and the basis for urinary biomonitoring of serum estrogenicity

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

Fleck, Stefanie C.; Twaddle, Nathan C.; Churchwell, Mona I.

Biomonitoring of human exposure to estrogens most frequently focuses on environmental and dietary estrogens, and infrequently includes measures of exposure to potent endogenous estrogens present in serum. Pregnancy is a developmentally sensitive period during which “added” serum estrogenicity exceeding normal intra-individual daily variability may be of particular relevance. Here, we made repeated measurements of serum concentrations of estrone (E1), estradiol (E2), estriol (E3), estetrol (E4), daidzein (DDZ), genistein (GEN) and bisphenol A (BPA) in thirty pregnant women using ultra-performance liquid chromatography coupled with tandem mass spectrometry detection (UPLC-MS/MS) and electrospray ionization (ESI). Serum E1, E2, and E3 concentrations varied significantlymore » (coefficients of variation 9–10%) with broad ranges across the cohort: 1.61–85.1 nM, 9.09–69.7 nM, and 1.5–36.3 nM respectively. BPA (undetected, estimated from total exposure), DDZ and GEN concentrations were 1-5 orders of magnitude lower. The 24-h urinary elimination profiles of endogenous estrogens were each strongly correlated with their corresponding serum concentrations (Pearson's Correlation Coefficients of 0.83 (E1), 0.84 (E2) and 0.94 (E3)). Lastly, a multivariate regression analysis produced equations for estimating serum concentrations of E1, E2, E3, E4, GEN and DDZ from urinary elimination rates and gestation period, an important step towards non-invasive biomonitoring for assessment of “added” estrogenicity during pregnancy.« less

Comparative estrogenicity of endogenous, environmental and dietary estrogens in pregnant women I: Serum levels, variability and the basis for urinary biomonitoring of serum estrogenicity

DOE PAGES

Fleck, Stefanie C.; Twaddle, Nathan C.; Churchwell, Mona I.; ...

2018-03-13

Biomonitoring of human exposure to estrogens most frequently focuses on environmental and dietary estrogens, and infrequently includes measures of exposure to potent endogenous estrogens present in serum. Pregnancy is a developmentally sensitive period during which “added” serum estrogenicity exceeding normal intra-individual daily variability may be of particular relevance. Here, we made repeated measurements of serum concentrations of estrone (E1), estradiol (E2), estriol (E3), estetrol (E4), daidzein (DDZ), genistein (GEN) and bisphenol A (BPA) in thirty pregnant women using ultra-performance liquid chromatography coupled with tandem mass spectrometry detection (UPLC-MS/MS) and electrospray ionization (ESI). Serum E1, E2, and E3 concentrations varied significantlymore » (coefficients of variation 9–10%) with broad ranges across the cohort: 1.61–85.1 nM, 9.09–69.7 nM, and 1.5–36.3 nM respectively. BPA (undetected, estimated from total exposure), DDZ and GEN concentrations were 1-5 orders of magnitude lower. The 24-h urinary elimination profiles of endogenous estrogens were each strongly correlated with their corresponding serum concentrations (Pearson's Correlation Coefficients of 0.83 (E1), 0.84 (E2) and 0.94 (E3)). Lastly, a multivariate regression analysis produced equations for estimating serum concentrations of E1, E2, E3, E4, GEN and DDZ from urinary elimination rates and gestation period, an important step towards non-invasive biomonitoring for assessment of “added” estrogenicity during pregnancy.« less

Role of long-chain fatty acyl-CoA esters in the regulation of metabolism and in cell signalling.

PubMed Central

Faergeman, N J; Knudsen, J

1997-01-01

The intracellular concentration of free unbound acyl-CoA esters is tightly controlled by feedback inhibition of the acyl-CoA synthetase and is buffered by specific acyl-CoA binding proteins. Excessive increases in the concentration are expected to be prevented by conversion into acylcarnitines or by hydrolysis by acyl-CoA hydrolases. Under normal physiological conditions the free cytosolic concentration of acyl-CoA esters will be in the low nanomolar range, and it is unlikely to exceed 200 nM under the most extreme conditions. The fact that acetyl-CoA carboxylase is active during fatty acid synthesis (Ki for acyl-CoA is 5 nM) indicates strongly that the free cytosolic acyl-CoA concentration is below 5 nM under these conditions. Only a limited number of the reported experiments on the effects of acyl-CoA on cellular functions and enzymes have been carried out at low physiological concentrations in the presence of the appropriate acyl-CoA-buffering binding proteins. Re-evaluation of many of the reported effects is therefore urgently required. However, the observations that the ryanodine-senstitive Ca2+-release channel is regulated by long-chain acyl-CoA esters in the presence of a molar excess of acyl-CoA binding protein and that acetyl-CoA carboxylase, the AMP kinase kinase and the Escherichia coli transcription factor FadR are affected by low nanomolar concentrations of acyl-CoA indicate that long-chain acyl-CoA esters can act as regulatory molecules in vivo. This view is further supported by the observation that fatty acids do not repress expression of acetyl-CoA carboxylase or Delta9-desaturase in yeast deficient in acyl-CoA synthetase. PMID:9173866

Size-dependent ROS production by palladium and nickel nanoparticles in cellular and acellular environments - An indication for the catalytic nature of their interactions.

PubMed

Neubauer, Nicole; Palomaeki, Jaana; Karisola, Piia; Alenius, Harri; Kasper, Gerhard

2015-01-01

Palladium and nickel nanoparticles with variable but narrowly defined primary particle sizes in the range of 4-27 nm were investigated toward their catalytic activity and their ability to produce reactive oxygen species (ROS). The agglomerate size in the gas phase was between 50 and 150 nm, after transfer into solution probably larger. The catalytic activity was measured on the basis of CO oxidation to CO2. The formation of ROS was determined after transferring the particles into phosphate buffered saline (PBS), via the 2',7'-dichlorofluorescein method in a cell-free environment and with THP-1 cells. Activities were normalized with regard to catalyst surface area to enable a meaningful comparison of size effects. The solubility was measured for both materials and found to be 2 µg/ml for Ni and below the detection limit of 0.8 µg/ml for Pd. In the concentration range of about 4-250 µg/ml both materials induced a significant production of ROS in both acellular and cellular environments, with palladium being more active than nickel by several orders of magnitude. On an equal surface area concentration basis, both acellular and cellular ROS production showed a pronounced dependence on the primary particle size, with a maximum in the vicinity of 12 nm. The surface-specific catalytic activity also had a maximum at that size range. The correlation of these size effects is both surprising and - in combination with the poor solubility of palladium and nickel in PBS solution - a strong argument in favor of a particulate, catalytic mechanism for ROS production.

Gamma ray evaluation of fast neutron irradiated on topaz from Sri Lanka by HPGe gamma ray spectrometry

NASA Astrophysics Data System (ADS)

Boonsook, K.; Kaewwiset, W.; Limsuwan, P.; Naemchanthara, K.

2017-09-01

The purpose of this study was to evaluate the radionuclide concentrations of London blue topaz after fast neutron irradiation. The London blue topaz was obtained from Sri Lanka which classified into dark and light colors in the shape of an oval and rectangle with small, medium and large size. The optical property and radionuclide concentrations of London blue topaz have been examine by UV-Visible spectroscopy and HPGe gamma ray spectrometry, respectively. The UV-absorption spectra of topaz was taken in the range of 300 to 800 nm at room temperature. The results showed that the absorption peak of topaz was observed with only broad peaks in the range of 550 to 700 nm and 630 nm that correlated to the O - center in hydroxyl sites which substitutes for fluorine in topaz structure. The radioactivity of dark and light colors in the shape of an oval and rectangle London blue topaz was in the range of 1.437 ± 0.014 to 21.551 ± 0.037 nCi/g (oval dark), 2.958 ± 0.031 to 6.748 ± 0.054 nCi/g (oval light) and 2.350 ± 0.014 to 43.952 ± 0.088 nCi/g (rectangle dark), 1.442 ± 0.023 to 6.748 ± 0.054 nCi/g (rectangle light), respectively. The decay rates of 46Sc, 182Ta and 54Mn isotopes created by irradiation showed that the decay time of the radioactive element depended on the size of the topaz so increased with decreasing the size of topaz. Moreover, the size of topaz also affect the absorption coefficient. This study is applied to predict time of residue dose of topaz for enhancement colorless topaz by neutron radiation treatment.

Hygroscopic properties of ultrafine particles at an urban site in northern Japan during the summer of 2011

NASA Astrophysics Data System (ADS)

Jung, Jinsang; Kawamura, Kimitaka

2013-04-01

To investigate the hygroscopic property of ultrafine particles, hygroscopic growth factors [g(RH)] of size-segregated atmospheric particles were measured at an urban site in Sapporo, northern Japan, during the summer of 2011. Hygroscopic growth factors at 85% RH [g(85%)] of freshly formed nucleation mode particles ranged from 1.11 to 1.28 with an average of 1.16 ± 0.06. These values are similar to those of secondary organic aerosols, suggesting that low volatile organic vapors are important to the growth of nucleated clusters into quasi-stable aerosol particles larger than 3 nm. Higher g(85%) values (range: 1.21-1.31, AVG: 1.27 ± 0.04) were obtained for grown Aitken mode nucleated particles. This result may indicate that the growth of freshly formed nucleation mode particles to the Aitken mode particles at the urban site can be attributed to condensation not only of low volatility organic vapors but also of highly water-soluble inorganic compounds like sulfuric acid. Diel variations in the number concentrations of less-hygroscopic particles [g(85%) <1.05] were similar to those in NO concentrations, suggesting that less-hygroscopic particles are mainly produced by local anthropogenic emissions such as traffic. Higher g(85%) values (1.27 ± 0.05) were obtained at a dry particle diameter of 120 nm when the air masses originated from downwind areas of the Asian continent, whereas lower g(85%) values (1.19 ± 0.06) were obtained when clean marine air masses arrived in the urban site. These results indicate that the hygroscopic property of large Aitken and small accumulation mode particles (80-165 nm) are highly influenced by the long-range transport of atmospheric particles.

Extending the wavelength range in the Oclaro high-brightness broad area modules

NASA Astrophysics Data System (ADS)

Pawlik, Susanne; Guarino, Andrea; Sverdlov, Boris; Müller, Jürgen; Button, Christopher; Arlt, Sebastian; Jaeggi, Dominik; Lichtenstein, Norbert

2010-02-01

The demand for high power laser diode modules in the wavelength range between 793 nm and 1060 nm has been growing continuously over the last several years. Progress in eye-safe fiber lasers requires reliable pump power at 793 nm, modules at 808 nm are used for small size DPSSL applications and fiber-coupled laser sources at 830 nm are used in printing industry. However, power levels achieved in this wavelength range have remained lower than for the 9xx nm range. Here we report on approaches to increasing the reliable power in our latest generations of high power pump modules in the wavelength range between 793 nm and 1060 nm.

Simultaneous anaerobic transformation of tetrachloroethene and carbon tetrachloride in a continuous flow column

NASA Astrophysics Data System (ADS)

Azizian, Mohammad F.; Semprini, Lewis

2016-07-01

Tetrachloroethene (PCE) and carbon tetrachloride (CT) were simultaneously transformed in a packed column that was bioaugmented with the Evanite culture (EV). The data presented here have been obtained over a period of 1930 days. Initially the column was continuously fed synthetic groundwater with PCE (0.1 mM), sulfate (SO42 -) (0.2 mM) and formate (2.1 mM) or lactate (1.1 mM), but not CT. In these early stages of the study the effluent H2 concentrations ranged from 7 to 19 nM, and PCE was transformed to ethene (ETH) (81 to 85%) and vinyl chloride (VC) (11 to 17%), and SO42 - was completely reduced when using either lactate or formate as electron donors. SO42 - reduction occurred concurrently with cis-DCE and VC dehalogenation. Formate was a more effective substrate for promoting dehalogenation based on electron donor utilization efficiency. Simultaneous PCE and CT tests found CT (0.015 mM) was completely transformed with 20% observed as chloroform (CF) and trace amounts of chloromethane (CM) and dichloromethane (DCM), but no methane (CH4) or carbon disulfide (CS2). PCE transformation to ETH improved with CT addition in response to increases in H2 concentrations to 160 nM that resulted from acetate formation being inhibited by either CT or CF. Lactate fermentation was negatively impacted after CT transformation tests, with propionate accumulating, and H2 concentrations being reduced to below 1 nM. Under these conditions both SO42 - reduction and dehalogenation were negatively impacted, with sulfate reduction not occurring and PCE being transformed to cis-dichloroethene (c-DCE) (52%) and VC (41%). Upon switching to formate, H2 concentrations increased to 40 nM, and complete SO42 - reduction was achieved, while PCE was transformed to ETH (98%) and VC (1%), with no acetate detected. Throughout the study PCE dehalogenation to ethene was positively correlated with the effluent H2 concentrations.

Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

NASA Technical Reports Server (NTRS)

Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

1996-01-01

This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

In vitro characterization and mosquito (Aedes aegypti) repellent activity of essential-oils-loaded nanoemulsions.

PubMed

Nuchuchua, Onanong; Sakulku, Usawadee; Uawongyart, Napaporn; Puttipipatkhachorn, Satit; Soottitantawat, Apinan; Ruktanonchai, Uracha

2009-01-01

The nanoemulsions composed of citronella oil, hairy basil oil, and vetiver oil with mean droplet sizes ranging from 150 to 220 nm were prepared and investigated both in vitro and in vivo. Larger emulsion droplets (195-220 nm) shifted toward a smaller size (150-160 nm) after high-pressure homogenization and resulted in higher release rate. We proposed that thin films obtained from the nanoemulsions with smaller droplet size would have higher integrity, thus increasing the vaporization of essential oils and subsequently prolonging the mosquito repellant activity. The release rates were fitted with Avrami's equations and n values were in the same range of 0.6 to 1.0, implying that the release of encapsulated limonene was controlled by the diffusion mechanism from the emulsion droplet. By using high-pressure homogenization together with optimum concentrations of 5% (w/w) hairy basil oil, 5% (w/w) vetiver oil (5%), and 10% (w/w) citronella oil could improve physical stability and prolong mosquito protection time to 4.7 h due to the combination of these three essential oils as well as small droplet size of nanoemulsion.

Characterization of Fe-doped SrTiO3/BaTiO3 multilayer films and their ethanol sensing applications

NASA Astrophysics Data System (ADS)

Supasai, Thidarat; Wisitsoraat, Anurat; Hodak, Satreerat

2010-03-01

Fe-doped SrTiO3/BaTiO3 multilayer films have been deposited on alumina substrate using a sol-gel spin coating technique. The field effect scanning electron microscope photographs revealed a mixture of round and facet-shaped crystals in the undoped films. This microstructure disappeared in Fe-doped films which adopted a more porous sponge-like structure. The grain size of the films decreased from 300 nm for undoped films to 100 nm and 70 nm with Fe doping concentrations of 4 and 8 wt%, respectively. The absorption edge energy for X-rays by Fe was found to be about 7121 eV consistent with Fe^2+ oxidation state. Interdigitated electrodes were applied on these films for ethanol gas sensing application. A sensitivity figure of merit based on the relative change in the resistance of the Fe-doped films 8 wt% film was found to be in the 1-3 range for ethanol doses of 100-1000 ppm when operating at 250 C and in the range of 3-10 when the operating temperature was 350 C.

Metal-Enhanced Fluorescence from Nanoparticulate Zinc Films

PubMed Central

Aslan, Kadir; Previte, Michael J.R.; Zhang, Yongxia; Geddes, Chris D.

2009-01-01

A detailed study of metal-enhanced fluorescence (MEF) from fluorophores in the blue-to- red spectral region placed in close proximity to thermally evaporated zinc nanostructured films is reported. The zinc nanostructured films were deposited onto glass microscope slides as individual particles and were 1–10 nm in height and 20–100 nm in width, as characterized by Atomic Force Microscopy. The surface plasmon resonance peak of the zinc nanostructured films was ≈ 400 nm. Finite-difference time-domain calculations for single and multiple nanostructures organized in a staggered fashion on a solid support predict, as expected, that the electric fields are concentrated both around and between the nanostructures. Additionally, Mie scattering calculations show that the absorption and scattering components of the extinction spectrum are dominant in the UV and visible spectral ranges, respectively. Enhanced fluorescence emission accompanied by no significant changes in excited state lifetimes of fluorophores with emission wavelengths in the visible blue-to-red spectral range near-to zinc nanostructured films were observed, implying that MEF from zinc nanostructured films is mostly due to an electric field enhancement effect. PMID:19946356

Preparation of ultrafine grained copper nanoparticles via immersion deposit method

NASA Astrophysics Data System (ADS)

Abbasi-Kesbi, Fatemeh; Rashidi, Ali Mohammad; Astinchap, Bandar

2018-03-01

Today, the exploration about synthesis of nanoparticles is much of interest to materials scientists. In this work, copper nanoparticles have been successfully synthesized by immersion deposit method in the absence of any stabilizing and reducing agents. Copper (II) sulfate pentahydrate as precursor salt and distilled water and Ethylene glycol as solvents were used. The copper nanoparticles were deposited on plates of low carbon steel. The effects of copper sulfate concentrations and solvent type were investigated. X-ray diffraction, scanning electron microscopy and UV-Visible spectroscopy were taken to investigate the crystallite size, crystal structure, and morphology and size distribution and the growth process of the nanoparticles of obtained Cu particles. The results indicated that the immersion deposit method is a particularly suitable method for synthesis of semispherical copper nanoparticles with the crystallites size in the range of 22 to 37 nm. By increasing the molar concentration of copper sulfate in distilled water solvent from 0.04 to 0.2 M, the average particles size is increased from 57 to 81 nm. The better size distribution of Cu nanoparticles was achieved using a lower concentration of copper sulfate. By increasing the molar concentration of copper sulfate in water solvent from 0.04 to 0.2, the location of the SPR peak has shifted from 600 to 630 nm. The finer Cu nanoparticles were formed using ethylene glycol instead water as a solvent. Also, the agglomeration and overlapping of nanoparticles in ethylene glycol were less than that of water solvent.

Receptor stimulated formation of inositol phosphates in cultures of bovine adrenal medullary cells: the effects of bradykinin, bombesin and neurotensin.

PubMed

Bunn, S J; Marley, P D; Livett, B G

1990-04-01

The ability of a number of drugs and neuropeptides to stimulate phosphoinositide metabolism in cultured bovine adrenal medullary cells has been assessed. Low concentrations (10 nM) of angiotensin II, bradykinin, histamine, arginine-vasopressin, and bombesin, and high (10 microM) concentrations of oxytocin, prostaglandins E1, and E2, beta-endorphin, and neurotensin stimulated significant accumulation of [3H]inositol phosphates in adrenal medullary cells preloaded with [3H)]inositol. Bradykinin stimulated a significant response at concentration as low as 10pM, with an EC50 of approximately 0.5 nM. The response was markedly inhibited by the bradykinin B2 antagonist [Thi5,8,D-Phe7] bradykinin but not the B1 antagonist [Des-Arg9,Leu8] bradykinin. Higher concentrations of bombesin and neurotensin were required to elicit a response (10 nM and 10 microM respectively). The bombesin response was sensitive to inhibition by the bombesin antagonist [D-Arg1,D-Pro2,D-Trp7,9Leu11]-substance P. In contrast, the neurotensin response was not reduced by the NT1 antagonist [D-Trp11]-neurotensin. These results indicate there are a number of agents that can stimulate phosphatidylinositide hydrolysis in the adrenal medullary cells by acting on different classes of receptors. Such a range of diverse agonists that stimulate inositol phosphate formation will facilitate further analysis of the phosphatidylinositide breakdown in chromaffin cell function.

Comparison of Eh and H2 measurements for delineating redox processes in a contaminated aquifer

USGS Publications Warehouse

Chapelle, Francis H.; Haack, Sheridan K.; Adriaens, Peter; Henry, Mark A.; Bradley, Paul M.

1996-01-01

Measurements of oxidation-reduction potential (Eh) and concentrations of dissolved hydrogen (H2) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. Eh measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured Eh and pH values on an equilibrium stability diagram indicated that Fe(III) reduction was the predominant redox process in the anoxic zone and did not indicate the presence of methanogenesis and sulfate reduction. In contrast, measurements of H2concentrations indicated that methanogenesis predominated in heavily contaminated sediments near the water table surface (H2 ∼ 7.0 nM) and that the methanogenic zone was surrounded by distinct sulfate-reducing (H2 ∼ 1-4 nM) and Fe(III)-reducing (H2 ∼ 0.1-0.8 nM) zones. The presence of methanogenesis, sulfate reduction, and Fe(III) reduction was confirmed by the distribution of dissolved oxygen, sulfate, Fe(II), and methane in groundwater. These results show that H2 concentrations were more useful for identifying anoxic redox processes than Ehmeasurements in this groundwater system. However, H2-based redox zone delineations are more reliable when H2 concentrations are interpreted in the context of electron-acceptor (oxygen, nitrate, sulfate) availability and the presence of final products [Fe(II), sulfide, methane] of microbial metabolism.

Concentration effect of Er{sup 3+} ions on structural and spectroscopic properties of CdNb{sub 2}O{sub 6} phosphors

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

Ghafouri, Sanaz Aian; Erdem, Murat, E-mail: merdem@marmara.edu.tr; Ekmekçi, M. Kaan

2014-12-15

Excitation and emission spectra of a visible room-temperature Er{sup 3+} ions luminescence from powders. - Highlights: • This is the first report on spectroscopic properties of CdNb{sub 2}O{sub 6}:Er{sup 3+}. • The crystalline sizes are affected as the concentration of Er{sup 3+} ions increased. • Quenching of the luminescence was observed to be above 1.0 mol% Er{sup 3+}. - Abstract: This study is focused on the synthesis and characterization of CdNb{sub 2}O{sub 6} compounds doped with of Er{sup 3+} ions. Powders were synthesized by using the molten salt method and annealed at 900 °C for 4 h. The synthesized particlesmore » were structurally characterized by using X-ray diffraction, scanning electron microscopy. A single phase of the CdNb{sub 2}O{sub 6} was determined and the size of the particles was found to be affected by the presence and the concentration of Er{sup 3+} ions. Luminescence properties of each sample were investigated by measuring accurately the emission and excitation spectra at room temperature in the wavelength range of 200–1700 nm by exciting the Er{sup 3+} ions at 379 nm and 805 nm. Quenching of the luminescence in both visible and near infrared spectral regions was observed to be above 1.0 mol% Er{sup 3+} concentration.« less

Colorimetric nanoplasmonic assay to determine purity and titrate extracellular vesicles.

PubMed

Maiolo, Daniele; Paolini, Lucia; Di Noto, Giuseppe; Zendrini, Andrea; Berti, Debora; Bergese, Paolo; Ricotta, Doris

2015-04-21

Extracellular Vesicles (EVs) - cell secreted vesicles that carry rich molecular information of the parental cell and constitute an important mode of intercellular communication - are becoming a primary topic in translational medicine. EVs (that comprise exosomes and microvesicles/microparticles) have a size ranging from 40 nm to 1 μm and share several physicochemical proprieties, including size, density, surface charge, and light interaction, with other nano-objects present in body fluids, such as single and aggregated proteins. This makes separation, titration, and characterization of EVs challenging and time-consuming. Here we present a cost-effective and fast colorimetric assay for probing by eye protein contaminants and determine the concentration of EV preparations, which exploits the synergy between colloidal gold nanoplasmonics, nanoparticle-protein corona, and nanoparticle-membrane interaction. The assay hits a limit of detection of protein contaminants of 5 ng/μL and has a dynamic range of EV concentration ranging from 35 fM to 35 pM, which matches the typical range of EV concentration in body fluids. This work provides the first example of the exploitation of the nanoparticle-protein corona in analytical chemistry.

Modeling particle nucleation and growth over northern California during the 2010 CARES campaign

NASA Astrophysics Data System (ADS)

Lupascu, A.; Easter, R.; Zaveri, R.; Shrivastava, M.; Pekour, M.; Tomlinson, J.; Yang, Q.; Matsui, H.; Hodzic, A.; Zhang, Q.; Fast, J. D.

2015-07-01

Accurate representation of the aerosol lifecycle requires adequate modeling of the particle number concentration and size distribution in addition to their mass, which is often the focus of aerosol modeling studies. This paper compares particle number concentrations and size distributions as predicted by three empirical nucleation parameterizations in the Weather Research and Forecast coupled with chemistry (WRF-Chem) regional model using 20 discrete size bins ranging from 1 nm to 10 μm. Two of the parameterizations are based on H2SO4 while one is based on both H2SO4 and organic vapors. Budget diagnostic terms for transport, dry deposition, emissions, condensational growth, nucleation, and coagulation of aerosol particles have been added to the model and are used to analyze the differences in how the new particle formation parameterizations influence the evolving aerosol size distribution. The simulations are evaluated using measurements collected at surface sites and from a research aircraft during the Carbonaceous Aerosol and Radiative Effects Study (CARES) conducted in the vicinity of Sacramento, California. While all three parameterizations captured the temporal variation of the size distribution during observed nucleation events as well as the spatial variability in aerosol number, all overestimated by up to a factor of 2.5 the total particle number concentration for particle diameters greater than 10 nm. Using the budget diagnostic terms, we demonstrate that the combined H2SO4 and low-volatility organic vapors parameterization leads to a different diurnal variability of new particle formation and growth to larger sizes compared to the parameterizations based on only H2SO4. At the CARES urban ground site, peak nucleation rates were predicted to occur around 12:00 Pacific (local) standard time (PST) for the H2SO4 parameterizations, whereas the highest rates were predicted at 08:00 and 16:00 PST when low-volatility organic gases are included in the parameterization. This can be explained by higher anthropogenic emissions of organic vapors at these times as well as lower boundary layer heights that reduce vertical mixing. The higher nucleation rates in the H2SO4-organic parameterization at these times were largely offset by losses due to coagulation. Despite the different budget terms for ultrafine particles, the 10-40 nm diameter particle number concentrations from all three parameterizations increased from 10:00 to 14:00 PST and then decreased later in the afternoon, consistent with changes in the observed size and number distribution. Differences among the three simulations for the 40-100 nm particle diameter range are mostly associated with the timing of the peak total tendencies that shift the morning increase and afternoon decrease in particle number concentration by up to two hours. We found that newly formed particles could explain up to 20-30 % of predicted cloud condensation nuclei at 0.5 % supersaturation, depending on location and the specific nucleation parameterization. A sensitivity simulation using 12 discrete size bins ranging from 1 nm to 10 μm diameter gave a reasonable estimate of particle number and size distribution compared to the 20 size bin simulation, while reducing the associated computational cost by ∼ 36 %.

In situ chemichromic studies of interactions between a lutetium bis-octaalkyl-substituted phthalocyanine and selected biological cofactors

PubMed Central

Pal, C.; Cammidge, A. N.; Cook, M. J.; Sosa-Sanchez, J. L.; Sharma, A. K.; Ray, A. K.

2012-01-01

Spin-coated films, approximately 100 nm thick, of a newly synthesized bis[octakis(octyl)phthalocyaninato] lutetium(III) complex on ultrasonically cleaned glass substrates exhibit pronounced chemichromic behaviour with potential application in healthcare. In situ kinetic optical absorption spectroscopic measurements show that the phthalocyanine Q-band is red shifted by 60 nm upon oxidation arising from exposure to bromine vapour. Recovery to the original state is achieved by the treatment of the oxidized films with nicotinamide adenine dinucleotide and l-ascorbic acid (vitamin C) in an aqueous solution containing 1.5 M lithium perchlorate. The neutralization process is found to be governed by first-order kinetics. The linear increase of the reduction rate with increasing concentration of cofactors provides a basis for calibration of analyte concentrations ranging from 3.5 mM down to 0.03 mM. PMID:21676969

Optimization and stabilization of gold nanoparticles by using herbal plant extract with microwave heating

NASA Astrophysics Data System (ADS)

Yasmin, Akbar; Ramesh, Kumaraswamy; Rajeshkumar, Shanmugam

2014-04-01

In this study, we have synthesized the gold nanoparticles by using Hibiscus rosa-sinensis, a medicinal plant. The gold nanoparticles were synthesized rapidly by the involvement of microwave heating. By changing of plant extract concentration, gold solution concentration, microwave heating time and power of microwave heating the optimized condition was identified. The surface Plasmon resonance found at 520 nm confirmed the gold nanoparticles synthesis. The spherical sized nanoparticles in the size range of 16-30 nm were confirmed by Transmission Electron Microscope (TEM). The stability of the nanoparticles is very well proved in the invitro stability tests. The biochemical like alkaloids and flavonoids play a vital role in the nanoparticles synthesis was identified using the Fourier Transform Infrared Spectroscopy (FTIR). Combining the phytochemical and microwave heating, the rapid synthesis of gold nanoparticles is the novel process for the medically applicable gold nanoparticles production.

Effects of excess oxygen on the 4.5-6.3 eV absorption spectra of oxygen-rich high purity silica

NASA Astrophysics Data System (ADS)

Magruder, R. H.; Robinson, S. J.

2016-05-01

Type III silica samples were implanted with O using a multi-energy process that produced a layer of constant concentration to within ±5% beginning ∼80 nm from the surface and extending to ∼640 nm below the surfaces of the samples. The concentrations of excess oxygen in the layer ranged from 0.035 to ∼2.1at.%. In these samples we show that E‧ centers and NBOHCs, as well as the normal cadre of ODC (II) centers, were suppressed, and the optical absorption from 4.7 to 6.4 eV was primarily due to oxygen excess defects. Using Gaussian fitting techniques to examine the optical difference spectra, we have been able to identify four defect centers that are related to excess oxygen defect bands at 4.76 eV, 5.42 eV, 5.75 eV and 6.25 eV.

Competitive immunoassay of phenobarbital by microchip electrophoresis with laser induced fluorescence detection.

PubMed

Huang, Yong; Zhao, Shulin; Shi, Ming; Liu, Jinwen; Liang, Hong

2011-05-23

A microchip electrophoresis method with laser induced fluorescence detection was developed for the immunoassay of phenobarbital. The detection was based on the competitive immunoreaction between analyte phenobarbital and fluorescein isothiocyanate (FITC) labeled phenobarbital with a limited amount of antibody. The assay was developed by varying the borate concentration, buffer pH, separation voltage, and incubation time. A running buffer system containing 35 mM borate and 15 mM sodium dodecyl sulfate (pH 9.5), and 2800 V separation voltage provided analysis conditions for a high-resolution, sensitive, and repeatable assay of phenobarbital. Free FITC-labeled phenobarbital and immunocomplex were separated within 30s. The calibration curve for phenobarbital had a detection limit of 3.4 nM and a range of 8.6-860.0 nM. The assay could be used to determine the phenobarbital plasma concentration in clinical plasma sample. Copyright © 2011 Elsevier B.V. All rights reserved.

The new method of real-time detection of 129I2, 129I127I, 127I2 and NO2 in gases using tunable diode laser operating in the range of 632-637 nm

NASA Astrophysics Data System (ADS)

Kireev, S. V.; Shnyrev, S. L.

2018-02-01

This paper develops the new selective real-time method of 129I2, 129I127I, 127I2 and NO2 detection in gases. Measuring concentrations of molecular iodine is based on fluorescence exciting by the radiation of a tunable diode laser, operating in the red spectral region (632-637 nm), at two or three wavelengths corresponding to the centers of the absorption lines of 129I2, 129I127I and 127I2. Detection of NO2 is performed by measuring the intensity of the tunable diode laser radiation, which passed through the measuring cell. Measured simultaneously, boundary ratios of iodine molecule concentrations measured simultaneously are about 10-6. The sensitivity of nitrogen dioxide detection is 1016 cm-3.

Effect of fentanyl and lidocaine on the end-tidal sevoflurane concentration preventing motor movement in dogs.

PubMed

Suarez, Martin A; Seddighi, Reza; Egger, Christine M; Rohrbach, Barton W; Cox, Sherry K; KuKanich, Butch K; Doherty, Thomas J

2017-01-01

OBJECTIVE To determine effects of fentanyl, lidocaine, and a fentanyl-lidocaine combination on the minimum alveolar concentration of sevoflurane preventing motor movement (MAC NM ) in dogs. ANIMALS 6 adult Beagles. PROCEDURES Dogs were anesthetized with sevoflurane in oxygen 3 times (1-week intervals). Baseline MAC NM (MAC NM-B ) was determined starting 45 minutes after induction of anesthesia. Dogs then received 1 of 3 treatments IV: fentanyl (loading dose, 15 μg/kg; constant rate infusion [CRI], 6 μg/kg/h), lidocaine (loading dose, 2 mg/kg; CRI, 6 mg/kg/h), and the fentanyl-lidocaine combination at the same doses. Determination of treatment MAC NM (MAC NM-T ) was initiated 90 minutes after start of the CRI. Venous blood samples were collected at the time of each treatment MAC NM measurement for determination of plasma concentrations of fentanyl and lidocaine. RESULTS Mean ± SEM overall MAC NM-B for the 3 treatments was 2.70 ± 0.27 vol%. The MAC NM decreased from MAC NM-B to MAC NM-T by 39%, 21%, and 55% for fentanyl, lidocaine, and the fentanyl-lidocaine combination, respectively. This decrease differed significantly among treatments. Plasma fentanyl concentration was 3.25 and 2.94 ng/mL for fentanyl and the fentanyl-lidocaine combination, respectively. Plasma lidocaine concentration was 2,570 and 2,417 ng/mL for lidocaine and the fentanyl-lidocaine combination, respectively. Plasma fentanyl and lidocaine concentrations did not differ significantly between fentanyl and the fentanyl-lidocaine combination or between lidocaine and the fentanyl-lidocaine combination. CONCLUSIONS AND CLINICAL RELEVANCE CRIs of fentanyl, lidocaine, and the fentanyl-lidocaine combination at the doses used were associated with clinically important and significant decreases in the MAC NM of sevoflurane in dogs.

Analysis of silver nanoparticles in antimicrobial products using surface-enhanced Raman spectroscopy (SERS).

PubMed

Guo, Huiyuan; Zhang, Zhiyun; Xing, Baoshan; Mukherjee, Arnab; Musante, Craig; White, Jason C; He, Lili

2015-04-07

Silver nanoparticles (AgNPs) are the most commonly used nanoparticles in consumer products. Concerns over human exposure to and risk from these particles have resulted in increased interest in novel strategies to detect AgNPs. This study investigated the feasibility of surface-enhanced Raman spectroscopy (SERS) as a method for the detection and quantification of AgNPs in antimicrobial products. By using ferbam (ferric dimethyl-dithiocarbamate) as an indicator molecule that binds strongly onto the nanoparticles, AgNPs detection and discrimination were achieved based on the signature SERS response of AgNPs-ferbam complexes. SERS response with ferbam was distinct for silver ions, silver chloride, silver bulk particles, and AgNPs. Two types of AgNPs with different coatings, citrate and polyvinylpirrolidone (PVP), both showed strong interactions with ferbam and induced strong SERS signals. SERS was effectively applicable for detecting Ag particles ranging from 20 to 200 nm, with the highest signal intensity in the 60-100 nm range. A linear relationship (R(2) = 0.9804) between Raman intensity and citrate-AgNPs concentrations (60 nm; 0-20 mg/L) indicates the potential for particle quantification. We also evaluated SERS detection of AgNPs in four commercially available antimicrobial products. Combined with ICP-MS and TEM data, the results indicated that the SERS response is primarily dependent on size, but also affected by AgNPs concentration. The findings demonstrate that SERS is a promising analytical platform for studying environmentally relevant levels of AgNPs in consumer products and related matrices.

Spectrophotometric and spectrofluorimetric determination of indacaterol maleate in pure form and pharmaceutical preparations: application to content uniformity.

PubMed

El-Ashry, S M; El-Wasseef, D R; El-Sherbiny, D T; Salem, Y A

2015-09-01

Two simple, rapid, sensitive and precise spectrophotometric and spectrofluorimetric methods were developed for the determination of indacaterol maleate in bulk powder and capsules. Both methods were based on the direct measurement of the drug in methanol. In the spectrophotometric method (Method I) the absorbance was measured at 259 nm. The absorbance-concentration plot was rectilinear over the range 1.0-10.0 µg mL(-1) with a lower detection limit (LOD) of 0.078 µg mL(-1) and lower quantification limit (LOQ) of 0.238 µg mL(-1). Meanwhile in the spectrofluorimetric method (Method II) the native fluorescence was measured at 358 nm after excitation at 258 nm. The fluorescence-concentration plot was rectilinear over the range of 1.0-40.0 ng mL(-1) with an LOD of 0.075 ng mL(-1) and an LOQ of 0.226 ng mL(-1). The proposed methods were successfully applied to the determination of indacaterol maleate in capsules with average percent recoveries ± RSD% of 99.94 ± 0.96 for Method I and 99.97 ± 0.81 for Method II. In addition, the proposed methods were extended to a content uniformity test according to the United States Pharmacopoeia (USP) guidelines and were accurate, precise for the capsules studied with acceptance value 3.98 for Method I and 2.616 for Method II. Copyright © 2015 John Wiley & Sons, Ltd.

Liquid chromatographic and spectrophotometric determination of diflucortolone valerate and isoconazole nitrate in creams.

PubMed

Karacan, Elif; Cağlayan, Mehmet Gokhan; Palabiyik, Ismail Murat; Onur, Feyyaz

2011-01-01

A new RP-LC method and two new spectrophotometric methods, principal component regression (PCR) and first derivative spectrophotometry, are proposed for simultaneous determination of diflucortolone valerate (DIF) and isoconazole nitrate (ISO) in cream formulations. An isocratic system consisting of an ACE C18 column and a mobile phase composed of methanol-water (95 + 5, v/v) was used for the optimal chromatographic separation. In PCR, the concentration data matrix was prepared by using synthetic mixtures containing these drugs in methanol-water (3 + 1, v/v). The absorbance data matrix corresponding to the concentration data matrix was obtained by measuring the absorbances at 29 wavelengths in the range of 242-298 nm for DIF and ISO in the zero-order spectra of their combinations. In first derivative spectrophotometry, dA/dlambda values were measured at 247.8 nm for DIF and at 240.2 nm for ISO in first derivative spectra of the solution of DIF and ISO in methanol-water (3 + 1, v/v). The linear ranges were 4.00-48.0 microg/mL for DIF and 50.0-400 microg/mL for ISO in the LC method, and 2.40-40.0 microg/mL for DIF and 60.0-260 microg/mL for ISO in the PCR and first derivative spectrophotometric methods. These methods were validated by analyzing synthetic mixtures. These three methods were successfully applied to two pharmaceutical cream preparations.

A new innovative spectrophotometric method for the simultaneous determination of sofosbuvir and ledipasvir

NASA Astrophysics Data System (ADS)

Mansour, Fotouh R.

2018-01-01

A new innovative spectrophotometric method is developed to determine the concentration ratios in binary mixtures by determining the zero crossing point in the first derivative of the gross curve. This relationship can be applied if the part of the UV spectrum of substance Y, that intersects with the overlaid spectra of substance X is straight. By plotting the intersection wavelength against the concentration ratio (Cx/Cy), a straight line was obtained with a co-efficient of determination equals 0.9999. As an application, simultaneous determination of sofosbuvir and ledipasvir in their binary mixtures was performed using two methods; a direct UV spectrophotometric method for determination of ledipasvir at 333 nm, and the new "wavelength-intersection ratio" method for determination of sofosbuvir. In the wavelength-intersection ratio method, different mixtures of sofosbuvir and ledipasvir containing different concentration ratios were prepared; the zero crossing point of the first derivative curve in the range 285 to 295 nm were determined for each mixture. An absorbance shift in the intersection was obtained with the change in the concentration ratio (sofosbuvir/ledipasvir). When the concentration ratio was plotted against the intersection wavelength, a straight line was obtained with a coefficient of determination of 0.9992. The direct method was linear in the range 3 to 18 μg/mL while the wavelength-intersection ratio method was linear in the range 11-110 μg/mL. The limits of detection were determined and found to be 0.5 and 3 μg/mL for ledipasvir and sofosbuvir, respectively. The accuracy and repeatability of the two methods were tested. The mean %recovery was found to be 100.19% and 100.75% for ledipasvir and sofosbuvir, respectively. The relative standard deviation was 0.57 for ledipasvir and 1.79 for sofosbuvir. The intermediate precision was also checked, the coefficients of variation for sofosbuvir and ledipasvir measurements between days did not exceed 1.88%.

In Vitro Activities of Benflumetol against 158 Senegalese Isolates of Plasmodium falciparum in Comparison with Those of Standard Antimalarial Drugs

PubMed Central

Pradines, Bruno; Tall, Adama; Fusai, Thierry; Spiegel, Andre; Hienne, Remi; Rogier, Christophe; Trape, Jean Francois; Le Bras, Jacques; Parzy, Daniel

1999-01-01

The 50% inhibitory concentration (IC50s) of benflumetol (range, 12.5 to 240 nM; mean, 55.1 nM) for 158 Senegalese isolates were evaluated. Ten isolates (6%) showed decreased susceptibility to benflumetol. Benflumetol was slightly more potent against chloroquine-resistant isolates (P < 0.025). No correlation or weak correlations in the responses to benflumetol and pyrimethamine, chloroquine, amodiaquine, artemether, quinine, and pyronaridine were observed, and these correlations are insufficient to suggest cross-resistance. Benflumetol may be an important alternative drug for the treatment of chloroquine-resistant malaria. PMID:9925550

Noninvasive In Vivo Monitoring of Cyanide Toxicity and Treatment Using Diffuse Optical Spectroscopy in a Rabbit Model

DTIC Science & Technology

2009-06-01

Finally. the tissue concentrations of oxyhe- moglobin (OIIb) dcoxyhcmoglogin ( RHb ). MetHb, and H,O arc calculated by a linear least squares tit of the...coefficients of the mam chro- mophores in the near infrared wmelength range between 600 :o 40 A - - OHb -- RHb IS ..... .. .J ’· · · · · M!!Hb 16 :liE _e...0 ·oo soo 900 1000 \\\\"A\\’EU:NGTH (nm) and I 000 nm. Figure I A show~ the exttnct1on coefficients of OHb. RHb . and MetHb and Figure I B shows the e

On the validity of the Poisson assumption in sampling nanometer-sized aerosols

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

Damit, Brian E; Wu, Dr. Chang-Yu; Cheng, Mengdawn

2014-01-01

A Poisson process is traditionally believed to apply to the sampling of aerosols. For a constant aerosol concentration, it is assumed that a Poisson process describes the fluctuation in the measured concentration because aerosols are stochastically distributed in space. Recent studies, however, have shown that sampling of micrometer-sized aerosols has non-Poissonian behavior with positive correlations. The validity of the Poisson assumption for nanometer-sized aerosols has not been examined and thus was tested in this study. Its validity was tested for four particle sizes - 10 nm, 25 nm, 50 nm and 100 nm - by sampling from indoor air withmore » a DMA- CPC setup to obtain a time series of particle counts. Five metrics were calculated from the data: pair-correlation function (PCF), time-averaged PCF, coefficient of variation, probability of measuring a concentration at least 25% greater than average, and posterior distributions from Bayesian inference. To identify departures from Poissonian behavior, these metrics were also calculated for 1,000 computer-generated Poisson time series with the same mean as the experimental data. For nearly all comparisons, the experimental data fell within the range of 80% of the Poisson-simulation values. Essentially, the metrics for the experimental data were indistinguishable from a simulated Poisson process. The greater influence of Brownian motion for nanometer-sized aerosols may explain the Poissonian behavior observed for smaller aerosols. Although the Poisson assumption was found to be valid in this study, it must be carefully applied as the results here do not definitively prove applicability in all sampling situations.« less

Molecular beacon anchored onto a graphene oxide substrate

NASA Astrophysics Data System (ADS)

Darbandi, Arash; Datta, Debopam; Patel, Krunal; Lin, Gary; Stroscio, Michael A.; Dutta, Mitra

2017-09-01

In this article, we report a graphene oxide-based nanosensor incorporating semiconductor quantum dots linked to DNA-aptamers that functions as a ‘turn-off’ fluorescent nanosensor for detection of low concentrations of analytes. A specific demonstration of this turn-off aptasensor is presented for the case of the detection of mercury (II) ions. In this system, ensembles of aptamer-based quantum-dot sensors are anchored onto graphene oxide (GO) flakes which provide a platform for analyte detection in the vicinity of GO. Herein, the operation of this ensemble-based nanosensor is demonstrated for mercury ions, which upon addition of mercury, quenching of the emission intensity from the quantum dots is observed due to resonance energy transfer between quantum dots and the gold nanoparticle connected via a mercury target aptamer. A key result is that the usually dominant effect of quenching of the quantum dot due to close proximity to the GO can be reduced to negligible levels by using a linker molecule in conjunctions with the aptamer-based nanosensor. The effect of ionic concentration of the background matrix on the emission intensity was also investigated. The sensor system is found to be highly selective towards mercury and exhibits a linear behavior (r 2 > 0.99) in the nanomolar concentration range. The detection limit of the sensor towards mercury with no GO present was found to be 16.5 nM. With GO attached to molecular beacon via 14 base, 35 base, and 51 base long linker DNA, the detection limit was found to be 38.4 nM, 9.45 nM, and 11.38 nM; respectively.

Physical constraints in the condensation of eukaryotic chromosomes. Local concentration of DNA versus linear packing ratio in higher order chromatin structures.

PubMed

Daban, J R

2000-04-11

The local concentration of DNA in metaphase chromosomes of different organisms has been determined in several laboratories. The average of these measurements is 0.17 g/mL. In the first level of chromosome condensation, DNA is wrapped around histones forming nucleosomes. This organization limits the DNA concentration in nucleosomes to 0. 3-0.4 g/mL. Furthermore, in the structural models suggested in different laboratories for the 30-40 nm chromatin fiber, the estimated DNA concentration is significantly reduced; it ranges from 0.04 to 0.27 g/mL. The DNA concentration is further reduced when the fiber is folded into the successive higher order structures suggested in different models for metaphase chromosomes; the estimated minimum decrease of DNA concentration represents an additional 40%. These observations suggest that most of the models proposed for the 30-40 nm chromatin fiber are not dense enough for the construction of metaphase chromosomes. In contrast, it is well-known that the linear packing ratio increases dramatically in each level of DNA folding in chromosomes. Thus, the consideration of the linear packing ratio is not enough for the study of chromatin condensation; the constraint resulting from the actual DNA concentration in metaphase chromosomes must be considered for the construction of models for condensed chromatin.

Quantifying time-varying cellular secretions with local linear models.

PubMed

Byers, Jeff M; Christodoulides, Joseph A; Delehanty, James B; Raghu, Deepa; Raphael, Marc P

2017-07-01

Extracellular protein concentrations and gradients initiate a wide range of cellular responses, such as cell motility, growth, proliferation and death. Understanding inter-cellular communication requires spatio-temporal knowledge of these secreted factors and their causal relationship with cell phenotype. Techniques which can detect cellular secretions in real time are becoming more common but generalizable data analysis methodologies which can quantify concentration from these measurements are still lacking. Here we introduce a probabilistic approach in which local-linear models and the law of mass action are applied to obtain time-varying secreted concentrations from affinity-based biosensor data. We first highlight the general features of this approach using simulated data which contains both static and time-varying concentration profiles. Next we apply the technique to determine concentration of secreted antibodies from 9E10 hybridoma cells as detected using nanoplasmonic biosensors. A broad range of time-dependent concentrations was observed: from steady-state secretions of 230 pM near the cell surface to large transients which reached as high as 56 nM over several minutes and then dissipated.

Effect of gold nanoparticles on the fluorescence excitation spectrum of α-fetoprotein: Local environment dependent fluorescence quenching

NASA Astrophysics Data System (ADS)

Li, Jian-jun; Chen, Yu; Wang, A.-qing; Zhu, Jian; Zhao, Jun-wu

2011-01-01

The effect of colloid gold nanoparticles (AuNPs) on the fluorescence excitation spectrum of α-fetoprotein (AFP) has been investigated experimentally. The excitation spectral peaks of AFP with low concentration from 0.01 ng ml -1 to 12 ng ml -1 increase monotonically with increasing of AFP concentration. When some gold colloids were added to the AFP solution, the excitation peak at 285 nm decreases distinctly. By comparing the excitation peak intensity of AFP solution with gold colloids and without gold colloids at different AFP concentrations, the quenching effect from gold nanoparticle was more effective at lower AFP concentration. So the range of concentration from 0.01 ng ml -1 to 0.09 ng ml -1 will be the potential range of applications because of the higher sensitivity. The physical origin based on local field effect was investigated to illuminate this local environment dependent fluorescence quenching. The changing extent of quenching with different AFP concentrations can be attributed to the nonlinear decreasing of the local field factor of gold nanoparticles as a function of environmental dielectric constant.

The Study of Compact Plasma Source of SXR of Vacuum Spark Type with Capillary Concentrator and It's Application

NASA Astrophysics Data System (ADS)

Kantsyrev, V. L.; Kopytok, K. I.; Shlyaptseva, A. S.

1994-03-01

The results are presented dealing with the working out and study of the plasma source of soft X-ray (SXR) of the new type. Experimental set up included compact low-inductance vacuum spark (LIVS) with initial energy supply equal up to 2.5 kJ and glass-capillary concentrator (GCC) of SXR. The characteristics of SXR of vacuum spark and properties of SXR were studied using diagnostic complex. The coefficient of conversion of initial energy supply into SXR (η) amounted to 0.01 in range 1.2nm. Value η had peak dependence on atomic number of anode Za. The spectra were recorded belonging to Ne-like, F-like ions of Fe, Cu ions and He-like, H-like ions of Al, Ti, Fe. Glass capillary concentrator consists of about several hundreds glass capillaries Flux density of SXR in focusing spot was up to 105-106 Wt/cm, density of energy is up to 20-30 mJ/cm2 at diameter of SXR focusing spot equal to about 2-3mm in the range 0.7-1.0 nm. The plasma source of the new type is intended for X-ray microscopy, study of influence of SXR on the surface of solid state. It allows to carry out experiments making only on electron synchrotronic sources of SXR.

The genus Rhodosporidium: a potential source of beta-carotene.

PubMed

de Miguel, T; Calo, P; Díaz, A; Villa, T G

1997-03-01

Four wild-type species of the genus Rhodosporidium have been studied as as possible sources for the industrial production of beta-carotene. HPLC-based studies showed that their carotenoid composition consisted of almost pure beta-carotene at concentrations ranging from 226 to 685 micrograms/g of dried yeast biomass. These results are consistent with those obtained by spectrophotometry at 480 nm.

Fluorescent carbon nanodots for sensitive and selective detection of tannic acid in wines.

PubMed

Ahmed, Gaber Hashem Gaber; Laíño, Rosana Badía; Calzón, Josefa Angela García; García, Marta Elena Díaz

2015-01-01

Herein we describe an easy one step synthesis of carbon nanodots (C-dots) by thermal carbonization of 6-bromohexylboronic acid using two different amine compounds, polyethyleneglycol bis(3-aminopropyl (PEGA) and 1,2-aminopropane (DPA), at 180 °C in atmospheric oxygen. The as-synthesized C-dots were characterized by FTIR, HRTEM, NMR and fluorescence. The C-dots prepared using PEGA showed a strong emission at 440 nm with excitation at 362 nm. These C-dots exhibited analytical potential as sensing probes for tannic acid (TA) determination. pH effect, interferences, and analytical performance of the method were investigated. The method was found effective in the linear concentration range from 0.1 to 10 mg L(-1) TA achieving a limit of detection equal 0.018 mg L(-1) TA. The applicability of the method was demonstrated by direct measurements of TA in red and white wine samples. Validation of the method was achieved by spiking the wine samples with different standard TA concentrations obtaining recoveries in the range (90-112.5%). A probable mechanism by which TA quenched the C-dots fluorescence was proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of three new condensation particle counters for sub-3 nm particle detection during the Helsinki CPC workshop: the ADI versatile water CPC, TSI 3777 nano enhancer and boosted TSI 3010

NASA Astrophysics Data System (ADS)

Kangasluoma, Juha; Hering, Susanne; Picard, David; Lewis, Gregory; Enroth, Joonas; Korhonen, Frans; Kulmala, Markku; Sellegri, Karine; Attoui, Michel; Petäjä, Tuukka

2017-06-01

In this study we characterized the performance of three new particle counters able to detect particles smaller than 3 nm during the Helsinki condensation particle counter (CPC) workshop in summer 2016: the Aerosol Dynamics Inc. (ADI; Berkeley, USA) versatile water condensation particle counter (vWCPC), TSI 3777 nano enhancer (TSI Inc., Shoreview, USA) and modified and boosted TSI 3010-type CPC from Université Blaise Pascal called a B3010. The performance of all CPCs was first measured with charged tungsten oxide test particles at temperature settings which resulted in supersaturation low enough to not detect any ions produced by a radioactive source. Due to similar measured detection efficiencies, additional comparison between the 3777 and vWCPC were conducted using electrically neutral tungsten oxide test particles and with positively charged tetradodecylammonium bromide. Furthermore, the detection efficiencies of the 3777 and vWCPC were measured with boosted temperature settings yielding supersaturation which was at the onset of homogeneous nucleation for the 3777 or confined within the range of liquid water for the ADI vWCPC. Finally, CPC-specific tests were conducted to probe the response of the 3777 to various inlet flow relative humidities, of the B3010 to various inlet flow rates and of the vWCPC to various particle concentrations. For the 3777 and vWCPC the measured 50 % detection diameters (d50s) were in the range of 1.3-2.4 nm for the tungsten oxide particles, depending on the particle charging state and CPC temperature settings, between 2.5 and 3.3 nm for the organic test aerosol, and in the range of 3.2-3.4 nm for tungsten oxide for the B3010.

Synaptosomal binding of 125I-labelled daboiatoxin, a new PLA2 neurotoxin from the venom of Daboia russelli siamensis.

PubMed

Maung-Maung-Thwin; Gopalakrishnakone, P; Yuen, R; Tan, C H

1996-02-01

Daboiatoxin (DbTx), the PLA2 neurotoxin from Daboia russelli siamensis venom, was shown to bind specifically and saturably to rat cerebrocortical synaptosomes and synaptic membrane fragments. Two families of binding sites were detected by equilibrium binding analysis in the presence and absence of Ca2+. Scatchard analysis of biphasic plateaus revealed Kdl 5 nM and Bmax1, 6 pmoles/mg protein, and Kd2 80 nM and Bmax2 20 pmoles/mg protein, respectively, for the high- and low-affinity binding sites. The binding of 125I-DbTx to synaptosomes did not show marked dependence on Ca2+, Mg2+, Co2+ and Sr2+. Native DbTx was the only strong competitor to 125I-DbTx synaptosomal binding (IC50 12.5 nM, KI 5.5 nM). Two other crotalid PLA2 neurotoxins, crotoxin CB and mojave toxin basic subunit, and nontoxic C. Atrox PLA2 enzyme, were relatively weaker inhibitors, while two viperid PLA2 neurotoxins, ammodytoxin A and VRV PL V, were very weak inhibitors. Crotoxin CA was a poor inhibitor even at microM concentrations, whereas no inhibitory effect at all was observed with crotoxin CACB, ammodytoxin C, VRV PL VIIIa, taipoxin, beta-bungarotoxin, or with PLA2 enzymes from N. naja venom, E. schistosa venom, bee venom and porcine pancreas. All other pharmacologically active ligands examined (epinephrine, norepinephrine, histamine, choline, dopamine, serotonin, GABA, naloxone, WB-4101, atropine, hexamethonium and alpha-bun-garotoxin) also failed to interfere with 125I-DbTx binding. As those competitors that showed partial inhibition were effective only at microM concentration range compared to the Kd (5 nM) of 125I-DbTx synaptosomal binding, DbTx could well recognize a different neuronal binding site. Rabbit anti-DbTx polyclonal antisera completely blocked the specific binding. When a range of Ca2+ and K+ channels modulators were examined, Ca2+ channel blockers (omega-conotoxins GVIA and MVIIC, taicatoxin, calciseptine and nitrendiprene) did not affect the binding even at high concentrations, while charybdotoxin was the only K+ channel effector that could partially displace 125I-DbTx synaptosomal binding amongst the K+ channel blockers tested (apamin, dendrotoxin-I, iberiotoxin, MCD-peptide, 4-aminopyridine and tetraethylammonium), suggesting that neither K+ nor Ca2+ channels are associated with DbTx binding sites.

11beta-hydroxysteroid dehydrogenase in the testis of Bufo arenarum: changes in its seasonal activity.

PubMed

Denari, Daniela; Ceballos, Nora R

2005-09-01

In rat Leydig cells, glucocorticoids (GC) inhibit testosterone (T) synthesis via glucocorticoid receptor (GR). However, GC access to GR is regulated by the local expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Two isoforms were identified in mammals: type 1, a NADP+-preferring enzyme with K(m) in the muM range for GC and type 2, NAD+-dependent, with K(m) in the nM range for GC. In amphibians, a seasonal rhythm in baseline GC levels was described. However, a shift in the amount of deactivating 11beta-HSD activity could alter GC effects. The purpose of this work is to describe seasonal changes in testicular activity of 11beta-HSD in Bufo arenarum as well as the annual and seasonal patterns of plasma corticosterone (B) and T. The activity of 11beta-HSD was assayed in homogenate and subcellular fractions in pre-reproductive (Pre-R), reproductive (R) and post-reproductive (Post-R) periods, using [3H]B. Plasma B and T were determined by RIA. Testicular 11beta-HSD is a microsomal NAD+-dependent enzyme with a K(m) in the nM order, its activity being strongly reduced by glycyrrhetinic acid. These results indicate that toad testes express an 11beta-HSD similar to mammalian type 2. Although 11beta-HSD activity is higher in the Post-R than in the R and Pre-R seasons (V(max): Pre-R: 0.26+/-0.10, R: 0.14+/-0.01, Post-R: 1.37+/-0.45, pmol/minmg protein), K(m) value remains constant throughout the year. A seasonal rhythm in baseline GC concentrations inversely correlated with plasma T was also described. T concentration is lower in the R season than in the other periods (Pre-R: 90+/-6; R: 12+/-1; Post-R: 56+/-3, nM) while total B concentration is higher in the breeding than in the other seasons (Pre-R: 62+/-10; R: 145+/-18; Post-R: 96+/-10, nM). Furthermore, free B (Pre-R: 51+/-8; R: 94+/-12; Post-R: 70+/-7, nM) was always below K(m) values. In conclusion, this work shows that the activity of 11beta-HSD in toad testes could modulate GC action by transforming active hormones in the corresponding inactive steroid.

Observations of urban airborne particle number concentrations during rush-hour conditions: analysis of the number based size distributions and modal parameters.

PubMed

Lingard, Justin J N; Agus, Emily L; Young, David T; Andrews, Gordon E; Tomlin, Alison S

2006-12-01

A summertime study of the number concentration and the size distribution of combustion derived nanometre sized particles (termed nanoparticles) from diesel and spark-ignition (SI) engine emissions were made under rush-hour and free-flow traffic conditions at an urban roadside location in Leeds, UK in July 2003. The measured total particle number concentrations (N(TOTAL)) were of the order 1.8 x 10(4) to 3.4 x 10(4) cm(-3), and tended to follow the diurnal traffic flow patterns. The N(TOTAL) was dominated by particles < or =100 nm in diameter which accounted for between 89-93% of the measured particle number. By use of a log-normal fitting procedure, the modal parameters of the number based particle size distribution of urban airborne particulates were derived from the roadside measurements. Four component modes were identified. Two nucleation modes were found, with a smaller, more minor, mode composed principally of sub-11 nm particles, believed to be derived from particles formed from the nucleation of gaseous species in the atmosphere. A second mode, much larger in terms of number, was composed of particles within the size range of 10-20 nm. This second mode was believed to be principally derived from the condensation of the unburned fuel and lube oil (the solvent organic fraction or SOF) as it cooled on leaving the engine exhaust. Third and fourth modes were noted within the size ranges of 28-65 nm and 100-160 nm, respectively. The third mode was believed to be representative of internally mixed Aitken mode particles composed of a soot/ash core with an adsorbed layer of readily volatilisable material. The fourth mode was believed to be composed of chemically aged, secondary particles. The larger nucleation and Aitken modes accounted for between 80-90% of the measured N(TOTAL), and the particles in these modes were believed to be derived from SI and diesel engine emissions. The overall size distribution, particularly in modes II-IV, was observed to be strongly related to the number of primary particle emissions, with larger count median diameters observed under conditions where low numbers of primary soot based particles were present.

Transition from fractional to classical Stokes-Einstein behaviour in simple fluids.

PubMed

Coglitore, Diego; Edwardson, Stuart P; Macko, Peter; Patterson, Eann A; Whelan, Maurice

2017-12-01

An optical technique for tracking single particles has been used to evaluate the particle diameter at which diffusion transitions from molecular behaviour described by the fractional Stokes-Einstein relationship to particle behaviour described by the classical Stokes-Einstein relationship. The results confirm a prior prediction from molecular dynamic simulations that there is a particle size at which transition occurs and show it is inversely dependent on concentration and viscosity but independent of particle density. For concentrations in the range 5 × 10 -3 to 5 × 10 -6  mg ml -1 and viscosities from 0.8 to 150 mPa s, the transition was found to occur in the diameter range 150-300 nm.

Simultaneous determination of the brand new two-drug combination for the treatment of hepatitis C: Sofosbuvir/ledipasvir using smart spectrophotometric methods manipulating ratio spectra

NASA Astrophysics Data System (ADS)

Eissa, Maya S.

2017-08-01

In this work, various sensitive and selective spectrophotometric methods were first introduced for the simultaneous determination of sofosbuvir and ledipasvir in their binary mixture without preliminary separation. Ledipasvir was determined simply by zero-order spectrophotometric method at its λmax = 333.0 nm in a linear range of 2.5-30.0 μg/ml without any interference of sofosbuvir even in low or high concentrations and with mean percentage recovery of 100.05 ± 0.632. Sofosbuvir can be quantitatively estimated by one of the following smart spectrophotometric methods based on ratio spectra developed for the resolution of the overlapped spectra of their binary mixture; ratio difference spectrophotometric method (RD) by computing the difference between the amplitudes of sofosbuvir ratio spectra at 228 nm and 270 nm, first derivative (DD1) of ratio spectra by measuring the sum of amplitude of trough and peak at 265 nm and 277 nm, respectively, ratio subtraction (RS) spectrophotometric method in which sofosbuvir can be successfully determined at its λmax = 261.0 nm and mean centering (MC) of ratio spectra by measuring the mean centering values at 270 nm. All of the above mentioned spectrophotometric methods can estimate sofosbuvir in a linear range of 7.5-90.0 μg/ml with mean percentage recoveries of 100.57 ± 0.810, 99.92 ± 0.759, 99.51 ± 0.475 and 100.75 ± 0.672, respectively. These methods were successfully applied to the analysis of their combined dosage form and bulk powder. The adopted methods were also validated as per ICH guidelines and statistically compared to an in-house HPLC method.

Simultaneous determination of the brand new two-drug combination for the treatment of hepatitis C: Sofosbuvir/ledipasvir using smart spectrophotometric methods manipulating ratio spectra.

PubMed

Eissa, Maya S

2017-08-05

In this work, various sensitive and selective spectrophotometric methods were first introduced for the simultaneous determination of sofosbuvir and ledipasvir in their binary mixture without preliminary separation. Ledipasvir was determined simply by zero-order spectrophotometric method at its λ max =333.0nm in a linear range of 2.5-30.0μg/ml without any interference of sofosbuvir even in low or high concentrations and with mean percentage recovery of 100.05±0.632. Sofosbuvir can be quantitatively estimated by one of the following smart spectrophotometric methods based on ratio spectra developed for the resolution of the overlapped spectra of their binary mixture; ratio difference spectrophotometric method (RD) by computing the difference between the amplitudes of sofosbuvir ratio spectra at 228nm and 270nm, first derivative (DD 1 ) of ratio spectra by measuring the sum of amplitude of trough and peak at 265nm and 277nm, respectively, ratio subtraction (RS) spectrophotometric method in which sofosbuvir can be successfully determined at its λ max =261.0nm and mean centering (MC) of ratio spectra by measuring the mean centering values at 270nm. All of the above mentioned spectrophotometric methods can estimate sofosbuvir in a linear range of 7.5-90.0μg/ml with mean percentage recoveries of 100.57±0.810, 99.92±0.759, 99.51±0.475 and 100.75±0.672, respectively. These methods were successfully applied to the analysis of their combined dosage form and bulk powder. The adopted methods were also validated as per ICH guidelines and statistically compared to an in-house HPLC method. Copyright © 2017 Elsevier B.V. All rights reserved.

Tunable stability of monodisperse secondary O/W nano-emulsions

NASA Astrophysics Data System (ADS)

Vecchione, R.; Ciotola, U.; Sagliano, A.; Bianchini, P.; Diaspro, A.; Netti, P. A.

2014-07-01

Stable and biodegradable oil in water (O/W) nano-emulsions can have a huge impact on a wide range of bio-applications, from food to cosmetics and pharmaceuticals. Emulsions, however, are immiscible systems unstable over time; polymer coatings are known to be helpful, but an effective procedure to stabilize monodisperse and biodegradable O/W nano-emulsions is yet to be designed. Here, we coat biodegradable O/W nano-emulsions with a molecular layer of biodegradable polyelectrolytes such as polysaccharides - like chitosan - and polypeptides - like polylysine - and effectively re-disperse and densify the polymer coating at high pressure, thus obtaining monodisperse and stable systems. In particular, focusing on chitosan, our tests show that it is possible to obtain unprecedented ultra-stable O/W secondary nano-emulsions (diameter sizes tunable from ~80 to 160 nm and polydispersion indices below 0.1) by combining this process with high concentrations of polymers. Depending on the polymer concentration, it is possible to control the level of coating that results in a tunable stability ranging from a few weeks to several months. The above range of concentrations has been investigated using a fluorescence-based approach with new insights into the coating evolution.Stable and biodegradable oil in water (O/W) nano-emulsions can have a huge impact on a wide range of bio-applications, from food to cosmetics and pharmaceuticals. Emulsions, however, are immiscible systems unstable over time; polymer coatings are known to be helpful, but an effective procedure to stabilize monodisperse and biodegradable O/W nano-emulsions is yet to be designed. Here, we coat biodegradable O/W nano-emulsions with a molecular layer of biodegradable polyelectrolytes such as polysaccharides - like chitosan - and polypeptides - like polylysine - and effectively re-disperse and densify the polymer coating at high pressure, thus obtaining monodisperse and stable systems. In particular, focusing on chitosan, our tests show that it is possible to obtain unprecedented ultra-stable O/W secondary nano-emulsions (diameter sizes tunable from ~80 to 160 nm and polydispersion indices below 0.1) by combining this process with high concentrations of polymers. Depending on the polymer concentration, it is possible to control the level of coating that results in a tunable stability ranging from a few weeks to several months. The above range of concentrations has been investigated using a fluorescence-based approach with new insights into the coating evolution. Electronic supplementary information (ESI) available: Experimental section, Fig. S1-S3, and Tables S1-S6. See DOI: 10.1039/c4nr02273d

Meta-Analysis of the Detection of Plant Pigment Concentrations Using Hyperspectral Remotely Sensed Data

PubMed Central

Huang, Jingfeng; Wei, Chen; Zhang, Yao; Blackburn, George Alan; Wang, Xiuzhen; Wei, Chuanwen; Wang, Jing

2015-01-01

Passive optical hyperspectral remote sensing of plant pigments offers potential for understanding plant ecophysiological processes across a range of spatial scales. Following a number of decades of research in this field, this paper undertakes a systematic meta-analysis of 85 articles to determine whether passive optical hyperspectral remote sensing techniques are sufficiently well developed to quantify individual plant pigments, which operational solutions are available for wider plant science and the areas which now require greater focus. The findings indicate that predictive relationships are strong for all pigments at the leaf scale but these decrease and become more variable across pigment types at the canopy and landscape scales. At leaf scale it is clear that specific sets of optimal wavelengths can be recommended for operational methodologies: total chlorophyll and chlorophyll a quantification is based on reflectance in the green (550–560nm) and red edge (680–750nm) regions; chlorophyll b on the red, (630–660nm), red edge (670–710nm) and the near-infrared (800–810nm); carotenoids on the 500–580nm region; and anthocyanins on the green (550–560nm), red edge (700–710nm) and near-infrared (780–790nm). For total chlorophyll the optimal wavelengths are valid across canopy and landscape scales and there is some evidence that the same applies for chlorophyll a. PMID:26356842

Plasmon-Induced Selective Enhancement of Green Emission in Lanthanide-Doped Nanoparticles.

PubMed

Zhang, Weina; Li, Juan; Lei, Hongxiang; Li, Baojun

2017-12-13

By introducing an 18 nm thick Au nanofilm, selective enhancement of green emission from lanthanide-doped (β-NaYF 4 :Yb 3+ /Er 3+ ) upconversion nanoparticles (UCNPs) is demonstrated. The Au nanofilm is deposited on a microfiber surface by the sputtering method and then covered with the UCNPs. The plasma on the surface of the Au nanofilm can be excited by launching a 980 nm wavelength laser beam into the microfiber, resulting in an enhancement of the local electric field and a strong thermal effect. A 36-fold luminescence intensity enhancement of the UCNPs at 523 nm is observed, with no obvious reduction in the photostability of the UCNPs. Further, the intensity ratios of the emissions at 523-545 nm and at 523-655 nm are enhanced with increasing pump power, which is attributed to the increasing plasmon-induced thermal effect. Therefore, the fabricated device is further demonstrated to exhibit an excellent ability in temperature sensing. By controlling the pump power and the UCNP concentration, a wide temperature range (325-811 K) and a high temperature resolution (0.035-0.046 K) are achieved in the fabricated device.

Energy transfer from Pr3+ to Gd3+ ions in BaB8O13 phosphor for phototherapy lamps

NASA Astrophysics Data System (ADS)

Tamboli, Sumedha; Nair, Govind B.; Dhoble, S. J.; Burghate, D. K.

2018-04-01

A series of BaB8O13 phosphors doped with different concentrations of Gd3+ ions and co-doped with Pr3+ ions were synthesized by solid state synthesis method. X-ray powder diffraction (XRD) analysis confirmed the formation of the compound in a crystalline and homogeneous form. Scanning Electron Microscopy (SEM) was performed to study the surface morphology of the compound and Fourier Transform Infrared (FT-IR) spectroscopy measurements determined the nature of bonding between elements of the compounds. The photoluminescence (PL) excitation spectra of BaB8O13:Gd3+ phosphor showed excitation peaks at 246 nm, 252 nm and 274 nm. The prominent emission peak was observed at 313 nm which is in narrow band ultraviolet B (NB-UVB) range. Energy transfer was achieved by co-doping Pr3+ ions with Gd3+ ions. PL decay time was also measured for BaB8O13: Gd3+, Pr3+ phosphor. Emission at 313 nm can be used for the treatment of skin diseases.

Gold particle formation via photoenhanced deposition on lithium niobate

NASA Astrophysics Data System (ADS)

Zaniewski, A. M.; Meeks, V.; Nemanich, R. J.

2017-05-01

In this work, we report on a technique to reduce gold chloride into sub-micron particles and nanoparticles. We use photoelectron transfer from periodically polarized lithium niobate (PPLN) illuminated with above band gap light to drive the surface reactions required for the reduction and particle formation. The particle sizes and distributions on the PPLN surface are sensitive to the solution concentration, with inhibited nucleation and large particles (>150 nm) for both low (2E-8M to 9E-7M) and high (1E-5M to 1E-3M) concentrations of gold chloride. At midrange values of the concentration, nucleation is more frequent, resulting in smaller sized particles (<150 nm). We compare the deposition process to that for silver, which has been previously studied. We find that the reduction of gold chloride into nanoparticles is inhibited compared to silver ion reduction, due to the multi-step reaction required for gold particle formation. This also has consequences for the resulting deposition patterns: while silver deposits into nanowires along boundaries between areas with opposite signed polarizations, such patterning of the deposition is not observed for gold, for a wide range of concentrations studied (2E-8 to 1E-3M).

Surgical smoke and ultrafine particles

PubMed Central

Brüske-Hohlfeld, Irene; Preissler, Gerhard; Jauch, Karl-Walter; Pitz, Mike; Nowak, Dennis; Peters, Annette; Wichmann, H-Erich

2008-01-01

Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 μm). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure. PMID:19055750

Dependence of performance of Si nanowire solar cells on geometry of the nanowires.

PubMed

Khan, Firoz; Baek, Seong-Ho; Kim, Jae Hyun

2014-01-01

The dependence of performance of silicon nanowires (SiNWs) solar cells on the growth condition of the SiNWs has been described. Metal-assisted electroless etching (MAE) technique has been used to grow SiNWs array. Different concentration of aqueous solution containing AgNO3 and HF for Ag deposition is used. The diameter and density of SiNWs are found to be dependent on concentration of solution used for Ag deposition. The diameter and density of SiNWs have been used to calculate the filling ratio of the SINWs arrays. The filling ratio is increased with increase in AgNO3 concentration, whereas it is decreased with increase in HF concentration. The minimum reflectance value achieved is ~1% for SiNWs of length of ~1.2 μ m in the wavelength range of 300-1000 nm. The performance and diode parameters strongly depend on the geometry of SiNWs. The maximum short circuit current density achieved is 35.6 mA/cm(2). The conversion efficiency of solar cell is 9.73% for SiNWs with length, diameter, and wire density of ~1.2 μ m, ~75 nm, and 90 μ m(-2), respectively.

Physical characterization of aerosol particles during the Chinese New Year’s firework events

NASA Astrophysics Data System (ADS)

Zhang, Min; Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Wang, Tao; Yang, Xin; Gong, Youguo; Geng, Fuhai; Chen, Changhong

2010-12-01

Measurements for particles 10 nm to 10 μm were taken using a Wide-range Particle Spectrometer during the Chinese New Year (CNY) celebrations in 2009 in Shanghai, China. These celebrations provided an opportunity to study the number concentration and size distribution of particles in an especial atmospheric pollution situation due to firework displays. The firework activities had a clear contribution to the number concentration of small accumulation mode particles (100-500 nm) and PM 1 mass concentration, with a maximum total number concentration of 3.8 × 10 4 cm -3. A clear shift of particles from nucleation and Aitken mode to small accumulation mode was observed at the peak of the CNY firework event, which can be explained by reduced atmospheric lifetimes of smaller particles via the concept of the coagulation sink. High particle density (2.7 g cm -3) was identified as being particularly characteristic of the firework aerosols. Recalculated fine particles PM 1 exhibited on average above 150 μg m -3 for more than 12 hours, which was a health risk to susceptible individuals. Integral physical parameters of firework aerosols were calculated for understanding their physical properties and further model simulation.

Crystal Structure Characterization of Thin Layer Zinc Oxide

NASA Astrophysics Data System (ADS)

Doyan, Aris; Susilawati; Azizatul Fitri, Siti; Ahzan, Sukainil

2017-05-01

In this research the characterization of the crystal structure of a thin layer of ZnO (zinc oxide) were synthesized by sol - gel method and spin coating deposited on a glass substrate. The samples were divided into three sol concentrations of 0.1, 0.3, 0.5 Molar and two deposition temperature is 350 °C, and 550 °C. UV-Vis. spectrophotometer results showed that in the spectrum of visible light (wavelength range 300-800 nm) has a transmittance value of which increases with increasing concentration and temperature deposition of zinc oxide, otherwise the value of the absorption and the band gap energy decreases with the addition of concentration and deposition temperature. The transmittances value of the highest and lowest absorption was 93.5% and 0.03 is at a concentration of 0.1 M and zinc oxide deposition temperature of 550 °C, with a value of band gap energy of 2.98 eV. The XRD results showed that the zinc oxide crystal orientation in the field of 013 with a crystal grain size 14.4472 nm. SEM results showed the surface morphology of zinc oxide such as rod-like.

Spatial-temporal bio-optical classification of dynamic semi-estuarine waters in western North America

NASA Astrophysics Data System (ADS)

Phillips, Stephen Robert; Costa, Maycira

2017-12-01

The use of standard ocean colour reflectance based algorithms to derive surface chlorophyll may have limited applicability for optically dynamic coastal waters due to the pre-defined coefficients based on global datasets. Reflectance based algorithms adjusted to regional optical water characteristics are a promising alternative. A class-based definition of optically diverse coastal waters was investigated as a first step towards the development of temporal and spatial constrained reflectance based algorithms for optically variable coastal waters. A large set of bio-optical data were collected as part of five research cruises and bi-weekly trips aboard a ship of opportunity in the west coast of Canada, to assess the spatial and temporal variability of above-water reflectance in this contrasted coastal environment. To accomplish this, in situ biophysical and optical measurements were collected in conjunction with above-water hyperspectral remote sensing reflectance (Rrs) at 145 stations. The concentrations of measured biophysical data varied considerably; chlorophyll a (Chla) (mean = 1.64, range: 0.10-7.20 μg l-1), total suspended matter (TSM) (3.09, 0.82-20.69 mg l-1), and absorption by chromophoric dissolved organic matter (CDOM) (acdom(443 nm)) (0.525, 0.007-3.072 m-1), thus representing the spatio-temporal variability of the Salish Sea. Optically, a similar large range was also found; particulate scattering (bp(650 nm)) (1.316, 0.250-7.450 m-1), particulate backscattering (bbp(650 nm)) (0.022, 0.005-0.097 m-1), total beam attenuation coefficient (ct(650)) (1.675, 0.371-9.537 m-1) and particulate absorption coefficient (ap(650 nm)) (0.345, 0.048-2.020 m-1). An empirical orthogonal function (EOF) analysis revealed that Rrs variability was highly correlated to bp (r = 0.90), bbp (r = 0.82) and concentration of TSM (r = 0.80), which highlighted the dominant role of water turbidity in this region. Hierarchical clustering analysis was applied to the normalized Rrs spectra to define optical water classes. Class 1 was defined by the highest Rrs values, particularly above 570 nm, indicating more turbid waters; Class 2 was dominated by high Chla and TSM concentrations, which is shown by high Rrs at 570 nm as well as fluorescence and absorption peaks; Class 3 shows strong fluorescence signatures accompanied by low TSM influence; and Class 4 is most representative of clear waters with a less defined absorption peak around 440 nm. By understanding the bio-optical factors which control the variability of the Rrs spectra this study aims to develop a sub-regional characterization of this coastal region aiming to improve bio-optical algorithms in this complex coastal area.

New NbCd2 Phase in Niobium-Cadmium Coating Films

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

2018-02-01

Solid solutions in the form of alloy coatings have been obtained for the first time in the Cd concentration range of 64.5% using ion-plasma sputtering and the codeposition of Nb and Cd ultrafine particles. This supports thermal fluctuation melting and the coalescence of fine particles. A coating of niobium and cadmium layers less than 2 nm thick at 68 at % Cd results in the formation of a new phase identified as NbCd2. The tetragonal fcc phase with lattice parameters a = 0.84357 nm and c = 0.54514 nm forms directly during film coating. XRD data for the identification of the intermetallic compound have been determined. The thermal stability of the NbCd 2 intermetallic compound is limited by 200°C. The properties of the synthesized NbCd 2 phase are typical of semiconductors.

Spatial and temporal characterization of traffic emissions in urban microenvironments with a mobile laboratory

NASA Astrophysics Data System (ADS)

Pirjola, L.; Lähde, T.; Niemi, J. V.; Kousa, A.; Rönkkö, T.; Karjalainen, P.; Keskinen, J.; Frey, A.; Hillamo, R.

2012-12-01

A measurement campaign by a mobile laboratory van was performed in urban microenvironments bounded by a busy street Mannerheimintie in the city center of Helsinki, Finland. The characteristics of spatiotemporally high-resolution pollutant concentrations were studied such as ultrafine particles in the size range of 3-414 nm, black carbon BC, fine particle mass PM2.5, as well as nitrogen oxides NO and NO2. In addition, the effects of street geometry and roadside structure on the local dispersion of traffic emissions were analyzed as well. Meteorological conditions stayed stable and the wind direction was perpendicular to Mannerheimintie during the campaign. The highest particle concentrations were ˜8 × 105 cm-3, of which around 94% was smaller than 40 nm. At the pavement, the average concentration was in maximum 5 × 104 cm-3; around 80% of the particles was smaller than 40 nm. The volatility fraction was 75% by number. Due to the street canyon effect by the surrounding buildings, the downwind concentrations were around 24% of the upwind concentrations for particle number, 28% of NO, 39% of BC and 70% of NO2 concentrations. Furthermore, the upwind concentrations were higher than the simultaneously measured concentrations within the traffic flow. In fact, the particle count was around 3-fold, BC 2.5-fold, PM2.5 and NO2 1.5-fold compared to the concentrations while driving. Thus, for this measurement site and under these meteorological conditions, the exposure to pedestrians and cyclist on the upwind pavement is even higher than the driver's exposure. If the downwind buildings were parallel to Mannerheimintie, the concentrations dropped significantly at the pavement and continued decreasing slightly in the courtyards. When the downwind buildings were perpendicular to Mannerheimintie, a gradual reduction in the concentrations between the buildings was observed. However, at a distance of approximately a hundred meters a parallel side street which was a street canyon, started to affect the concentrations resulting in an increased exposure risk for pedestrians and cyclists. Understanding the local transport and the dispersion of traffic emissions are important for city planning and air quality assessment.

Different Spectrophotometric Methods for Simultaneous Determination of Trelagliptin and Its Acid Degradation Product.

PubMed

Mowaka, Shereen; Ayoub, Bassam M; Hassan, Mostafa A; Zaghary, Wafaa A

2018-01-01

New spectrophotometric and chemometric methods were carried out for the simultaneous assay of trelagliptin (TRG) and its acid degradation product (TAD) and applied successfully as a stability indicating assay to recently approved Zafatek® tablets. TAD was monitored using TLC to ensure complete degradation. Furthermore, HPLC was used to confirm dealing with one major acid degradation product. The proposed methods were developed by manipulating zero-order, first-derivative, and ratio spectra of TRG and TAD using simultaneous equation, first-derivative, and mean-centering methods, respectively. Using Spectra Manager II and Minitab v.14 software, the absorbance at 274 nm-260.4 nm, amplitudes at 260.4 nm-274.0 nm, and mean-centered values at 287.6 nm-257.2 nm were measured against methanol as a blank for TRG and TAD, respectively. Linearity and the other validation parameters were acceptable at concentration ranges of 5-50  μ g/mL and 2.5-25  μ g/mL for TRG and TAD, respectively. Using one-way analysis of variance (ANOVA), the optimized methods were compared and proved to be accurate for the simultaneous assay of TRG and TAD.

Validated spectrophotometric methods for simultaneous determination of troxerutin and carbazochrome in dosage form

NASA Astrophysics Data System (ADS)

Khattab, Fatma I.; Ramadan, Nesrin K.; Hegazy, Maha A.; Al-Ghobashy, Medhat A.; Ghoniem, Nermine S.

2015-03-01

Four simple, accurate, sensitive and precise spectrophotometric methods were developed and validated for simultaneous determination of Troxerutin (TXN) and Carbazochrome (CZM) in their bulk powders, laboratory prepared mixtures and pharmaceutical dosage forms. Method A is first derivative spectrophotometry (D1) where TXN and CZM were determined at 294 and 483.5 nm, respectively. Method B is first derivative of ratio spectra (DD1) where the peak amplitude at 248 for TXN and 439 nm for CZM were used for their determination. Method C is ratio subtraction (RS); in which TXN was determined at its λmax (352 nm) in the presence of CZM which was determined by D1 at 483.5 nm. While, method D is mean centering of the ratio spectra (MCR) in which the mean centered values at 300 nm and 340.0 nm were used for the two drugs in a respective order. The two compounds were simultaneously determined in the concentration ranges of 5.00-50.00 μg mL-1 and 0.5-10.0 μg mL-1 for TXN and CZM, respectively. The methods were validated according to the ICH guidelines and the results were statistically compared to the manufacturer's method.

Assessment of exposure risk of polychlorinated biphenyls to interior least terns (Sterna antillarum)

USGS Publications Warehouse

Sanchez, B.C.; Caldwell, C.A.

2008-01-01

Risk of polychlorinated biphenyl (PCB) exposure and effects were assessed for a colony of federally endangered interior least terns (Sterna antillarum) nesting on the Bitter Lake National Wildlife Refuge (NM, USA). The colony feeds from an area on the Refuge (Hunter Marsh/Oxbow Complex) wherein fish with elevated concentrations of total PCBs have been documented. Concentrations of total PCBs in whole fish averaged 0.94 mg/kg with a maximum concentration of 2.77 mg/kg, wet weight. Estimated daily PCB intake rates by adult birds throughout their 180-d breeding season ranged from <0.01 mg/kg/d to 0.98 mg/kg/d, yielding hazard quotients that ranged from 0.01 to 21.68. Polychlorinated biphenyls pose a moderate risk to the colony of interior least terns that breed at the Bitter Lake National Wildlife Refuge, but the exposure rate is not likely to threaten their overall breeding success. ?? 2008 SETAC.

The Sentinel 4 focal plane subsystem

NASA Astrophysics Data System (ADS)

Hohn, Rüdiger; Skegg, Michael P.; Hermsen, Markus; Hinger, Jürgen; Williges, Christian; Reulke, Ralf

2017-09-01

The Sentinel 4 instrument is an imaging spectrometer, developed by Airbus under ESA contract in the frame of the joint European Union (EU)/ESA COPERNICUS program with the objective of monitoring trace gas concentrations. Sentinel 4 will provide accurate measurements of key atmospheric constituents such as ozone, nitrogen dioxide, sulfur dioxide, formaldehyde, as well as aerosol and cloud properties. Sentinel 4 is unique in being the first geostationary UVN mission. The SENTINEL 4 space segment will be integrated on EUMETSAT's Meteosat Third Generation Sounder satellite (MTG-S). Sentinel 4 will provide coverage of Europe and adjacent regions. The Sentinel 4 instrument comprises as a major element two Focal Plane Subsystems (FPS) covering the wavelength ranges 305 nm to 500 nm (UVVIS) and 750 nm to 775 nm (NIR) respectively. The paper describes the Focal Plane Subsystems, comprising the detectors, the optical bench and the control electronics. Further the design and development approach will be presented as well as first measurement results of FPS Qualification Model.

Upwelled spectral radiance distribution in relation to particulate matter in sea water

NASA Technical Reports Server (NTRS)

Clark, D. K.; Strong, A. E.; Baker, E. T.

1980-01-01

Spectral analysis of water color and concurrent measurements of the relative concentration of various particulate and dissolved constituents within a broad range of water types are necessary to quantify ocean color observations and successfully relate them to various biological and physical processes that can be monitored by remote sensing. Some of the results of a Nimbus-G prelaunch cruise in connection with the Coastal Zone Color Scanner (CZCS) experiment, which was carried out in the Gulf of Mexico in October 1977, are presented and discussed. Based upon a small but diverse sample of near-surface measurements, it appears possible to estimate total suspended particulate matter (SPM) to useful accuracies by forming ratios of the spectral radiances measured at wavelengths falling near the centers of certain CZCS bands, viz., 440 nm:550 nm and 440 nm:520 nm. Furthermore, the analysis suggests a very high degree of covariation between SPM and phytoplankton pigments except for certain well-defined special cases.

Silver nanoparticles-based colorimetric array for the detection of Thiophanate-methyl

NASA Astrophysics Data System (ADS)

Zheng, Mingda; Wang, Yingying; Wang, Chenge; Wei, Wei; Ma, Shuang; Sun, Xiaohan; He, Jiang

2018-06-01

A simple and selective colorimetric sensor based on citrate capped silver nanoparticles (Cit-AgNPs) is proposed for the detection of Thiophanate-methyl (TM) with high sensitivity and selectivity. The method based on the color change of Cit-AgNPs from yellow to cherry red with the addition of TM to Cit-AgNPs that caused a red-shift on the surface plasmon resonance (SPR) band from 394 nm to 525 nm due to the hydrogen-bonding and substitution. The density functional theory (DFT) method was also calculated the interactions between the TM and citrate ions. Under the optimized conditions, a linear relationship between the absorption ratio (A525nm/A394nm) and TM concentration was found in the range of 2-100 μM with correlation coefficient (R2) of 0.988. The detection limit of TM was 0.12 μM by UV-vis spectrometer. Moreover, the applicability of colorimetric sensor is successfully verified by the detection of TM in environmental samples with good recoveries.

Spatially resolved frequency domain phosphorescence lifetime-based oxygen sensing for photodynamic therapy

NASA Astrophysics Data System (ADS)

Lai, Benjamin; Gurari, Mark; Wee, Wallace; Lilge, Lothar

2008-06-01

Photodynamic Therapy (PDT) is a minimally invasive treatment that uses a photosensitive drug into convert triplet state oxygen (3O2) to singlet oxygen (1O2) to destroy malignant tissue. A fiber-optic system based on frequency domain detection of phosphorescence quenching by 3O2 is described which optically measures the distribution of 3O2 in the treatment volume during PDT to permit adjustments of treatment parameters to improve outcome. A specially designed fiber optic probe containing phosphorescent sensors embedded along its length permit spatially resolved measurements. Each sensor is composed of a phosphorescent metalloporphyrin compound that emits a characteristic spectrum. Four candidate sensors with high absorption at the excitation wavelength of 405nm and emission in the 650nm to 700nm region are considered. The dependence of phosphorescence lifetime (τ) on 3O2 concentration is described by the linearized Stern-Volmer relationship as being inversely proportional. Determination of τ, and hence 3O2 concentration, is accomplished in the frequency domain by means of phase-modulation detection of the phosphorescence signal due to an amplitude modulated excitation. The τ's of each sensor are recovered by performing global non-linear least squares fit on the measured phase and modulation index over a range of frequencies and wavelengths. With the τ of each sensor known, the oxygen concentration at each sensor's location can be determined with the Stern-Volmer relationship.

Towards multifunctional cellulosic fabric: UV photo-reduction and in-situ synthesis of silver nanoparticles into cellulose fabrics.

PubMed

Rehan, Mohamed; Barhoum, Ahmed; Van Assche, Guy; Dufresne, Alain; Gätjen, Linda; Wilken, Ralph

2017-05-01

Herein, the highly multifunctional cotton fabric surfaces were designed with excellent coloration, UV-protection function, and antimicrobial activity. These multifunctional functions were developed by in-situ synthesis of silver nanoparticles (Ag NPs) into the cotton fabric surface using a simple green one-pot "UV-reduction" method. Cotton fabrics were pretreated with non-anionic detergent, immersed into alcoholic silver nitrate solution (concentration ranging from 100 to 500ppm), squeezed to remove excess solution and then exposed to UV-irradiation (range 320-400nm) for 1h. The influence UV-irradiation on the thermal, chemical, optical and biological properties of the cotton fabric surface was discussed in details. The UV-irradiation promotes reducing of Ag + ions and the cotton fabrics act as seed medium for Ag NPs formation by "heterogeneous nucleation". Increasing Ag + concentration (from 100 to 500ppm) results in Ag NPs of particle size (distribution) of 50-100nm. Interestingly, the Ag NPs exhibited different localized surface Plasmon resonance properties causing a coloration of the cotton fabrics with different color shades ranging from bright to dark brown with excellent color fastness properties. The treated cotton fabrics also show high protecting functions against UV-transmission (reduction of 65%) and Escherichia coli growth (99%). The side-effects of the UV-reduction process are further investigated. Published by Elsevier B.V.

Turbulent heat transfer and nanofluid flow in a protruded ribbed square passage

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Kothiyal, Alok Darshan; Bisht, Mangal Singh; Kumar, Anil

In this article, turbulent heat transfer of nanofluid flow in square passage with protruded rib shape is numerically and experimentally studied over Reynolds number ranges of 4000-18000. Different nanoparticles (Al2O3, CuO, and ZnO), with different concentration (φ) range of 1-4% and different nanoparticle diameter (dnp) range of 30-45 nm are disperse in water (base fluid). Several parameters such as stream wise distance (Xs /dp) range of 1.4-2.6, span wise distance (Ys /dp) range of 1.4-2.6, ratio of protruded height to print diameter (ep /dp) range of 0.83-1.67 also studied to find the consequence on thermal and hydrodynamic characteristics. Simulations were carried out to obtain heat and fluid flow behaviour of smooth and ribbed square channel using commercial CFD software, ANSYS 15.0 (Fluent). Renormalization k - ε model was employed to assess the influence of protruded ribs on turbulent flow and velocity field. The outcome indicates that Al2O3 nanofluid has the highest value of average Nusselt number as compare to other nanofluids. The average Nusselt number increases as the concentration increases and it decreases as nanoparticle diameter increases. The thermal hydrodynamic performance parameter based on equal pumping power, average Nusselt number and average friction factor were found to be highest for Al2O3, φ = 0.04, dnp = 30 nm, Xs /dp = 1.8, Ys /dp = 1.8 and ep /dp = 1.0 . The numerical data are compared with the corresponding experimental data. Comparison between CFD and experimental analysis results showed that good agreement as the data fell within ±7.0% error band.

Differential response of normal human fibroblasts to bombesin versus thrombin.

PubMed

Hendey, B; Mamrack, M D

1988-09-01

Normal human diploid fibroblasts (WS-1 cells) were growth-arrested under serum-free conditions for 48 hr. The addition of fetal bovine serum (10% final concentration) to these cells stimulated [3H]-thymidine incorporation into DNA and phosphoinositide breakdown over nine-fold. Thrombin, at concentrations above 0.1 unit/ml (u/ml), was also effective at stimulating DNA synthesis and phosphoinositide breakdown as well as causing a rise in intracellular pH. In contrast, the peptide bombesin (concentrations ranging from 1 nM to 100 nM) stimulated phosphoinositide breakdown but did not enhance DNA synthesis or cause an increase in cytoplasmic pH. The time course of accumulation of inositol phosphates differed in response to these agents. The thrombin effect peaked rapidly and leveled off after 5 min while the bombesin effect showed a constant increase for 30 min. Serum showed an intermediate response. The different rates of inositol phosphate accumulation observed with the two growth factors is viewed as representing a difference in the mechanism of phosphoinositide turnover. The relationship between the difference in phosphoinositide turnover and the initiation of DNA synthesis is also discussed.

Liquid chromatographic determination of acriflavine and proflavine residues in channel catfish muscle.

PubMed

Plakas, S M; el Said, K R; Jester, E L; Bencsath, F A; Hayton, W L

1997-01-01

A liquid chromatographic (LC) method was developed for determination of acriflavine (ACR) and proflavine (PRO) residues in channel catfish muscle. Residues were extracted with acidified methanol solution, and extracts were cleaned up with C18 solid-phase extraction columns. Residue concentrations were determined on an LC cyano column, with spectrophotometric detection at 454 nm. Catfish muscle was individually fortified with ACR (purified from commercial product) and PRO at concentrations of 5, 10, 20, 40, and 80 ppb (5 replicates per level). Mean recoveries from fortified muscle at each level ranged from 86 to 95%, with relative standard deviations (RSDs) of 2.5 to 5.7%. The method was applied to incurred residues of ACR and PRO in muscle after waterborne exposure of channel catfish to commercial acriflavine (10 ppm total dye for 4 h). RSDs for incurred residues of ACR and PRO were in the same range as those for fortified muscle. Low residue concentrations (< 1% of exposure water concentration) suggested poor absorption of ACR and PRO in catfish.

Enhancing reproducibility of SALDI MS detection by concentrating analytes within laser spot.

PubMed

Teng, Fei; Zhu, Qunyan; Wang, Yalei; Du, Juan; Lu, Nan

2018-03-01

Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI TOF MS) has become one of the most important analytical methods due to its less interference at low molecular weight range. However, it is still a challenge to obtain a good reproducibility of SALDI TOF MS because of the inhomogeneous distribution of analyte molecules induced by coffee ring effect. We propose a universal and reliable method to eliminate the coffee ring effect by concentrating all the analyte molecules within the laser spot. This method exhibits an excellent reproducibility of spot-to-spot and substrate-to-substrate, and the relative standard deviations (RSDs) for different concentrations are lower than 12.6%. It also performs good linear dependency (R 2 > 0.98) in the log-log plot with the concentration range of 1nM to 1μM, and the limit of detection for R6G is down to 1fmol. Copyright © 2017 Elsevier B.V. All rights reserved.

Photoluminescence of Reduced Graphene Oxide Prepared from Old Coconut Shell with Carbonization Process at Varying Temperatures

NASA Astrophysics Data System (ADS)

Jayanti, Dwi Noor; Yogi Nugraheni, Ananda; Kurniasari; Anjelh Baqiya, Malik; Darminto

2017-05-01

Reduced graphene oxide (rGO) powder has been prepared from coconut shells by carbonization process at 400°C, 600°C, 800°C and 1000°C for 5 hours at ambient air. In this study the exfoliation rGO was added into distilled water with variation of concentration solution using the sonication process for 3 hours and centrifugation at 4000 rpm for 20 minutes. The characterization were performed by using XRD and photoluminescence (PL) spectroscopy. The photoluminescence or rGO showed the peak of excitation and emission at wavelengths ranging from 340 nm to 800 nm. The PL emission spectra are at wavelength ranging from UV to visible region approaching red. Observation showed that the photoluminescence intensity was significantly increased by the increasing content of rGO in the solution. The influence of the varying temperature on the PL spectra will also be discussed in this study.

Liquid-chromatographic determination of sarafloxacin residues in channel catfish muscle-tissue

USGS Publications Warehouse

Meinertz, J.R.; Dawson, V.K.; Gingerich, W.H.; Cheng, B.; Tubergen, M.M.

1994-01-01

A liquid chromatographic method is described for the determination of sarafloxacin hydrochloride residues i n channel catfish (ictalurus punctatus) fillets. Sarafloxacin was extracted from fillet tissue with acetonitrile=water (1 + 1). The extract was centrifuged and the supernatant was partitioned with hexane. The aqueous fraction was filtered through a 0.45 Mum filter and evaporated to dryness. The sample was redissolved with 20% acetonitrile-methanol (3 + 2) and 80% trifluoroacetic acid (0.1%), Centrifuged, and filtered to remove proteins. Samples were analyzed by chromatography with gradient elution on a c18 column and with fluorescence detection (excitation at 280 nm and emission above 389 nm). Mean recoveries ranged from 85.4 To 104%, and relative standard deviations ranged from 1.06 To 5.58% In samples spiked at concentrations of 10.0-863.8 Ng/g. The method detection limit for sarafloxacin was 1.4 Ng/g.

Targeting survivin with prodigiosin isolated from cell wall of Serratia marcescens induces apoptosis in hepatocellular carcinoma cells.

PubMed

Yenkejeh, R A; Sam, M R; Esmaeillou, M

2017-04-01

Abnormal activation of the Wnt/β-catenin signaling pathway increases survivin expression that is involved in hepatocarcinogenesis. Therefore, downregulation of survivin may provide an attractive strategy for treatment of hepatocellular carcinoma. In this regard, little is known about the anticancer effects of prodigiosin isolated from cell wall of Serratia marcescens on the survivin expression and induction of apoptosis in hepatocellular carcinoma cells. Human hepatocellular carcinoma (HepG2) cells were treated with 100-, 200-, 400-, and 600-nM prodigiosin after which morphology of cells, cell number, growth inhibition, survivin expression, caspase-3 activation, and apoptotic rate were evaluated by inverted microscope, hemocytometer, MTT assay, RT-PCR, fluorometric immunosorbent enzyme assay, and flow cytometric analysis, respectively. Prodigiosin changed morphology of cells to apoptotic forms and disrupted cell connections. This compound significantly increased growth inhibition rate and decreased metabolic activity of HepG2 cells in a dose- and time-dependent manner. After 24-, 48-, and 72-h treatments with prodigiosin at concentrations ranging from 100 nM to 600 nM, growth inhibition rates were measured to be 1.5-10%, 24-47.5%, and 55.5-72.5%, respectively, compared to untreated cells. At the same conditions, metabolic activities were measured to be 91-83%, 74-53%, and 47-31% for indicated concentrations of prodigiosin, respectively, compared to untreated cells. We also found that treatment of HepG2 cells for 48 h decreased significantly cell number and survivin expression and increased caspase-3 activation in a dose-dependent manner. Specifically, treatment with 600-nM prodigiosin resulted in 77% decrease in cell number, 88.5% decrease in survivin messenger RNA level, and 330% increase in caspase-3 activation level compared to untreated cells. An increase in the number of apoptotic cells (late apoptosis) ranging from 36.9% to 97.4% was observed with increasing prodigiosin concentrations. From our data, prodigiosin is an attractive compound that turns the profile of high-level survivin expression in hepatocellular carcinoma cells into that of normal cells and may provide a novel approach to the hepatocellular carcinoma-targeted therapy.

Detection of Non-Photochemical Superoxide in Coastal and Open Ocean Seawater: Particulate Versus Dissolved Sources

NASA Astrophysics Data System (ADS)

Roe, K. L.; Rand, T.; Hansel, C. M.; Voelker, B. M.

2016-02-01

Superoxide radical (O2-) could have a significant effect on marine metal redox chemistry, but little data exists on its marine concentrations. In this study, we measured superoxide steady-state concentrations in both filtered and unfiltered samples collected near the California coast and at Station ALOHA. Particle-generated superoxide, defined as the difference between unfiltered and filtered concentrations, ranged from undetectable to 0.019 nM at Station ALOHA and from undetectable to 0.052 nM in samples from the southern California Current. We also show that a transient superoxide signal is generated during filtering, an artifact that may have affected previously reported concentrations of particle-generated superoxide in the ocean. High concentrations of superoxide (range) were measured in filtered samples from ALOHA station and the California Current, raising concerns about possible sources of background signals. Further study of background signals revealed that some superoxide production occurs even in artificial seawater and very aged filtered seawater samples, and that a small additional background signal is generated as the sample travels from the container to the flow cell where it is mixed with reagent for CL analysis. However, filtered seawater samples collected from the Scripps Pier had significantly higher superoxide production rates than those measured in artificial seawater, and production rates in unfiltered samples were no higher than those in filtered samples. Therefore, production by dissolved sources was the dominant non-photochemical source of superoxide in these samples. Production rates decreased in the presence of DTPA, suggesting involvement of metal ions in superoxide production. Laboratory experiments with natural organic matter (NOM) indicate that superoxide formation occurs during oxidation of reduced moieties of NOM by oxygen.

Optimized optical devices for edge-coupling-enabled silicon photonics platform

NASA Astrophysics Data System (ADS)

Png, Ching Eng; Ang, Thomas Y. L.; Ong, Jun Rong; Lim, Soon Thor; Sahin, Ezgi; Chen, G. F. R.; Tan, D. T. H.; Guo, Tina X.; Wang, Hong

2018-02-01

We present a library of high-performance passive and active silicon photonic devices at the C-band that is specifically designed and optimized for edge-coupling-enabled silicon photonics platform. These devices meet the broadband (100 nm), low-loss (< 2dB per device), high speed (>= 25 Gb/s), and polarization diversity requirements (TE and TM polarization extinction ratio <= 25 dB) for optical communication applications. Ultra-low loss edge couplers, broadband directional couplers, high-extinction ratio polarization beam splitters (PBSs), and high-speed modulators are some of the devices within our library. In particular, we have designed and fabricated inverse taper fiber-to-waveguide edge couplers of tip widths ranging from 120 nm to 200 nm, and we obtained a low coupling loss of 1.80+/-0.28 dB for 160 nm tip width. To achieve polarization diversity operation for inverse tapers, we have experimentally realized different designs of polarization beam splitters (PBS). Our optimized PBS has a measured extinction ratio of <= 25 dB for both the quasiTE modes, and quasi-TM modes. Additionally, a broadband (100 nm) directional coupler with a 50/50 power splitting ratio was experimentally realized on a small footprint of 20×3 μm2 . Last but not least, high-speed silicon modulators with a range of carrier doping concentrations and offset of the PN junction can be used to optimise the modulation efficiency, and insertion losses for operation at 25 GHz.

Optical and electrical properties of TiOPc doped Alq3 thin films

NASA Astrophysics Data System (ADS)

Ramar, M.; Suman, C. K.; Tyagi, Priyanka; Srivastava, R.

2015-06-01

The Titanyl phthalocyanine (TiOPc) was doped in Tris (8-hydroxyquinolinato) aluminum (Alq3) with different concentration. The thin film of optimized doping concentration was studied extensively for optical and electrical properties. The optical properties, studied using ellipsometry, absorption and photoluminescence. The absorption peak of Alq3 and TiOPc was observed at 387 nm and 707 nm and the photo-luminescence intensity (PL) peak of doped thin film was observed at 517 nm. The DC and AC electrical properties of the thin film were studied by current density-voltage (J-V) characteristics and impedance over a frequency range of 100 Hz - 1 MHz. The electron mobility calculated from trap-free space-charge limited region (SCLC) is 0.17×10-5 cm2/Vs. The Cole-Cole plots shows that the TiOPc doped Alq3 thin film can be represented by a single parallel resistance RP and capacitance CP network with a series resistance RS (10 Ω). The value of RP and CP at zero bias was 1587 Ω and 2.568 nF respectively. The resistance RP decreases with applied bias whereas the capacitance CP remains almost constant.

An external template-free route to uniform semiconducting hollow mesospheres and their use in photocatalysis.

PubMed

Yang, Di; Wang, Mengye; Zou, Bin; Zhang, Gu Ling; Lin, Zhiqun

2015-08-14

Solid amorphous TiO2 mesospheres were synthesized by controlled hydrolysis of Ti-containing precursors. Subsequently, solid TiO2 mesospheres were exploited as scaffolds and subjected to a one-step external template-free hydrothermal treatment, yielding intriguing hollow anatase TiO2 mesospheres. The synthetic protocol was optimized by investigating the effect of buffer reagents and fluoride ions on the formation of hollow TiO2 spheres. The diameter of hollow mesospheres, ranging from 308 to 760 nm, can be readily tailored by varying the precursor concentration. The average thickness of a shell composed of TiO2 nanocrystals was approximately 40 nm with a mean crystal size of 12.4-20.0 nm. Such hollow TiO2 mesospheres possessed a large surface area and were employed in photocatalytic degradation of methylene blue under UV irradiation. Interestingly, the synthetic conditions were found to exert a significant influence on the photocatalytic ability of hollow TiO2 mesospheres. The correlation between the degradation ability of hollow TiO2 mesospheres and the precursor concentration as well as the hydrothermal time was scrutinized. The optimal photocatalytic performance of hollow TiO2 mesospheres was identified.

Determination of ammonium on an integrated microchip with LED-induced fluorescence detection.

PubMed

Xue, Shuhua; Uchiyama, Katsumi; Li, Hai-Fang

2012-01-01

A simply fabricated microfluidic device integrated with a fluorescence detection system has been developed for on-line determination of ammonium in aqueous samples. A 365-nm light-emitting diode (LED) as an excitation source and a minor band pass filter were mounted into a polydimethylsiloxane (PDMS)-based microchip for the purpose of miniaturization of the entire analytical system. The ammonium sample reacted with o-phthaldialdehyde (OPA) on-chip with sodium sulfite as reducing reagent to produce a fluorescent isoindole derivative, which can emit fluorescence signal at about 425 nm when excited at 365 nm. Effects of pH, flow rate of solutions, concentrations of OPA-reagent, phosphate and sulfite salt were investigated. The calibration curve of ammonium in the range of 0.018-1.8 microg/mL showed a good linear relationship with R2 = 0.9985, and the detection limit was (S/N = 3) 3.6 x 10(-4) microg/mL. The relative standard deviation was 2.8% (n = 11) by calculating at 0.18 microg/mL ammonium for repeated detection. The system was applied to determine the ammonium concentration in rain and river waters, even extent to other analytes fluorescence detection by the presented device.

Characterizations of Pr-doped Yb3Al5O12 single crystals for scintillator applications

NASA Astrophysics Data System (ADS)

Yoshida, Yasuki; Shinozaki, Kenji; Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-04-01

Yb3Al5O12 (YbAG) single crystals doped with different concentrations of Pr were synthesized by the Floating Zone (FZ) method. Then, we evaluated their basic optical and scintillation properties. All the samples showed photoluminescence (PL) with two emission bands appeared approximately 300-500 nm and 550-600 nm due to the charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. A PL decay profile of each sample was approximated by a sum of two exponential decay functions, and the obtained decay times were 1 ns and 3-4 ns. In the scintillation spectra, we observed emission peaks in the ranges from 300 to 400 nm and from 450 to 550 nm for all the samples. The origins of these emissions were attributed to charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. The scintillation decay times became longer with increasing the Pr concentrations. Among the present samples, the 0.1% Pr-doped sample showed the lowest scintillation afterglow level. In addition, pulse height spectrum of 5.5 MeV α-rays was demonstrated using the Pr-doped YbAG, and we confirmed that all the samples showed a full energy deposited peak. Above all, the 0.1% Pr-doped sample showed the highest light yield with a value of 14 ph/MeV under α-rays excitation.

Spectroscopic properties and energy transfer analysis of Tm3+-doped BaF2-Ga2O3-GeO2-La2O3 glass.

PubMed

Yu, Shenglei; Yang, Zhongmin; Xu, Shanhui

2010-05-01

This paper reports on the spectroscopic properties and energy transfer analysis of Tm(3+)-doped BaF(2)-Ga(2)O(3)-GeO(2)-La(2)O(3) glasses with different Tm(2)O(3) doping concentrations (0.2, 0.5, 2.0, 2.5, 3.0, 3.5, 3.5, 4.0 wt%). Mid-IR fluorescence intensities in the range of 1,300 nm-2,200 nm have been measured when excited under an 808 nm LD for all the samples with the same pump power. Energy level structure and Judd-Ofelt parameters have been calculated based on the absorption spectra of Tm(3+), cross-relaxation rates and multi-phonon relaxation rates have been estimated with different Tm(2)O(3) doping concentrations. The maximum fluorescence intensity at around 1.8 mum has been obtained in Tm(2)O(3)-3 wt% sample and the maximum value of calculated stimulated emission cross-section of Tm(3+) in this sample is about 0.48 x 10(-20) cm(2) at 1,793 nm, and there is not any crystallization peak in the DSC curve of this sample, which indicate the potential utility of Tm(3+)-doped BaF(2)-Ga(2)O(3)-GeO(2)- La(2)O(3) glass for 2.0-microm optical fiber laser.

Luminescence studies and infrared emission of erbium-doped calcium zirconate phosphor.

PubMed

Tiwari, Neha; Dubey, Vikas

2016-05-01

The near-infrared-to-visible upconversion luminescence behaviour of Er(3+)-doped CaZrO3 phosphor is discussed in this manuscript. The phosphor was prepared by a combustion synthesis technique that is suitable for less-time-taking techniques for nanophosphors. The starting materials used for sample preparation were Ca(NO3)2.4H2O, Zr(NO3)4 and Er(NO3)2, and urea was used as a fuel. The prepared sample was characterized by X-ray diffraction (XRD). The surface morphology of prepared phosphor was determined by field emission gun scanning electron microscopy (FEGSEM). The functional group analysis was determined by Fourier transform infrared (FTIR) spectroscopy. All prepared phosphors with variable Er(3+) concentrations (0.5-2.5 mol%) were studied by photoluminescence analysis. It was found that the excitation spectra of the prepared phosphor showed a sharp excitation peak centred at 980 nm. The emission spectra with variable Er(3+) concentrations showed strong peaks in the 555 nm and 567 nm range, with a dominant peak at 555 nm due to the ((2)H(11/2),(4)S(3/2)) transition and a weaker transition at 567 nm associated with 527 nm. Spectrophotometric determination of the peak was evaluated by the Commission Internationale de I'Eclairage (CIE) method These upconverted emissions were attributed to a two-photon process. The excitation wavelength dependence of the upconverted luminescence, together with its time evolution after infrared pulsed excitation, suggested that energy transfer upconversion processes were responsible for the upconversion luminescence. The upconversion mechanisms were studied in detail through laser power dependence. Excited state absorption and energy transfer processes were discussed as possible upconversion mechanisms. The cross-relaxation process in Er(3+) was also investigated. Copyright © 2015 John Wiley & Sons, Ltd.

Association of phycoerythrin and phycocyanin: in vitro formation of a functional energy transferring phycobilisome complex of Porphyridium sordidum

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

Lipschultz, C.A.; Gantt, E.

1981-01-01

Functional in vitro association and dissociation of a phycobiliprotein complex, isolated from phycobilisomes of the red alga Porphyridium sordidum, were studied. The complex contained large bangiophyceaen phycoerythrin and cyanophytan phycocyanin in an equimolar ratio and had absorption maxima at 625, 567, and 550 nm and a shoulder at 495 nm. Emission at 655 nm (with excitation at 545 nm) from phycocyanin indicated functional coupling. The complex was stable over a wide buffer concentration range, and, notably, it was maximally stable in low phosphate, <0.01 M, unlike the phycobilisomes, which dissociate at this concentration. Its molecular weight was estimated to bemore » ca. 510 000, and by electron microscopy it was seen to consist of two units of similar size. The complex in 0.1 M phosphate was separated on a sucrose gradient into a homogeneous phycoerythrin band and a spectrally heterogeneous phycocyanin band. In vitro association of phycoerythrin and phycocyanin resulted in a complex with the same absorbance, emission, sedimentation, and molar pigment ratio as those of the native complex. The spectrally heterogeneous phycocyanin fractions from the dissociation gradient varied in the degree of association with phycoerythrin. Phycocyanin fractions absorbing from 622 to 633 nm exhibited high associability (>70%), whereas those with maxima at 617-620 nm had low associability (<30%). The presence of a 30 000 molecular weight polypeptide accompanied high associability, where it was ca. 2-fold more prominent. It is suggested that this polypeptide is involved in complex formation and could serve either in the stabilization of the conformational state of cyanophytan phycocyanin or as a direct linker between phycobiliproteins.« less

In situ study of binding of copper by fulvic acid: comparison of differential absorbance data and model predictions.

PubMed

Yan, Mingquan; Dryer, Deborah; Korshin, Gregory V; Benedetti, Marc F

2013-02-01

This study examined the binding of copper(II) by Suwannee River fulvic acid (SRFA) using the method of differential absorbance that was used at environmentally-relevant concentrations of copper and SRFA. The pH- and metal-differential spectra were processed via numeric deconvolution to establish commonalities seen in the changes of absorbance caused by deprotonation of SRFA and its interactions with copper(II) ions. Six Gaussian bands were determined to be present in both the pH- and Cu-differential spectra. Their maxima were located, in the order of increasing wavelengths at 208 nm, 242 nm, 276 nm, 314 nm, 378 nm and 551 nm. The bands with these maxima were denoted as A0, A1, A2, A3, A4 and A5, respectively. Properties of these bands were compared with those existing in the spectra of model compounds such as sulfosalicylic acid (SSA), tannic acid (TA), and polystyrenesulfonic acid-co-maleic acid (PSMA). While none of the features observed in differential spectra of the model compound were identical to those present in the case of SRFA, Gaussian bands A1, A3 and possibly A2 were concluded to be largely attributable to a combination of responses of salicylic- and polyhydroxyphenolic groups. In contrast, bands A4 and A5 were detected in the differential spectra of SRFA only. Their nature remains to be elucidated. To examine correlations between the amount of copper(II) bound by SRFA and changes of its absorbance, differential absorbances measured at indicative wavelengths 250 nm and 400 nm were compared with the total amount of SRFA-bound copper estimated based on Visual MINTEQ calculations. This examination showed that the differential absorbances of SRFA in a wide range of pH values and copper concentrations were strongly correlated with the concentration of SRFA-bound copper. The approach presented in this study can be used to generate in situ information concerning the nature of functional groups in humic substances engaged in interactions with metals ions. This information can be useful for further elaboration and development of detailed theoretic models that describe the complexation of metals in the environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Statistical analysis and parameterization of the hygroscopic growth of the sub-micrometer urban background aerosol in Beijing

NASA Astrophysics Data System (ADS)

Wang, Yu; Wu, Zhijun; Ma, Nan; Wu, Yusheng; Zeng, Limin; Zhao, Chunsheng; Wiedensohler, Alfred

2018-02-01

The take-up of water of aerosol particles plays an important role in heavy haze formation over North China Plain, since it is related with particle mass concentration, visibility degradation, and particle chemistry. In the present study, we investigated the size-resolved hygroscopic growth factor (HGF) of sub-micrometer aerosol particles (smaller than 350 nm) on a basis of 9-month Hygroscopicity-Tandem Differential Mobility Analyzer measurement in the urban background atmosphere of Beijing. The mean hygroscopicity parameter (κ) values derived from averaging over the entire sampling period for particles of 50 nm, 75 nm, 100 nm, 150 nm, 250 nm, and 350 nm in diameters were 0.14 ± 0.07, 0.17 ± 0.05, 0.18 ± 0.06, 0.20 ± 0.07, 0.21 ± 0.09, and 0.23 ± 0.12, respectively, indicating the dominance of organics in the sub-micrometer urban aerosols. In the spring, summer, and autumn, the number fraction of hydrophilic particles increased with increasing particle size, resulting in an increasing trend of overall particle hygroscopicity with enhanced particle size. Differently, the overall mean κ values peaked in the range of 75-150 nm and decreased for particles larger than 150 nm in diameter during wintertime. Such size-dependency of κ in winter was related to the strong primary particle emissions from coal combustion during domestic heating period. The number fraction of hydrophobic particles such as freshly emitted soot decreased with increasing PM2.5 mass concentration, indicating aged and internal mixed particles were dominant in the severe particulate matter pollution. Parameterization schemes of the HGF as a function of relative humidity (RH) and particle size between 50 and 350 nm were determined for different seasons and pollution levels. The HGFs calculated from the parameterizations agree well with the measured HGFs at 20-90% RH. The parameterizations can be applied to determine the hygroscopic growth of aerosol particles at ambient conditions for the area of Beijing (ultrafine and fine particles) and the North China plain (fine particles).

Laboratory measurement of the absorption coefficient of riboflavin for ultraviolet light (365 nm).

PubMed

Iseli, Hans Peter; Popp, Max; Seiler, Theo; Spoerl, Eberhard; Mrochen, Michael

2011-03-01

Corneal cross-linking (CXL) is an increasingly used treatment technique for stabilizing the cornea in keratoconus. Cross-linking (polymerization) between collagen fibrils is induced by riboflavin (vitamin B2) and ultraviolet light (365 nm). Although reported to reach a constant value at higher riboflavin concentrations, the Lambert-Beer law predicts a linear increase in the absorption coefficient. This work was carried out to determine absorption behavior at different riboflavin concentrations and to further investigate the purported plateau absorption coefficient value of riboflavin and to identify possible bleaching effects. The Lambert-Beer law was used to calculate the absorption coefficient at various riboflavin concentrations. The following investigated concentrations of riboflavin solutions were prepared using a mixture of 0.5% riboflavin and 20% Dextran T500 dissolved in 0.9% sodium chloride solution: 0%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%, and were investigated with and without aperture plate implementation. An additional test series measured the transmitted power at selected riboflavin concentrations over time. In diluted solutions, a linear correlation exists between the absorption coefficient and riboflavin concentration. The absorption coefficient reaches a plateau, but this occurs at a higher riboflavin concentration (0.1%) than previously reported (just above 0.04%). Transmitted light power increases over time, indicating a bleaching effect of riboflavin. The riboflavin concentration can be effectively varied as a treatment parameter in a considerably broader range than previously thought. Copyright 2011, SLACK Incorporated.

Ultrafine particle concentrations in and around idling school buses

NASA Astrophysics Data System (ADS)

Zhang, Qunfang; Fischer, Heidi J.; Weiss, Robert E.; Zhu, Yifang

2013-04-01

Unnecessary school bus idling increases children's exposure to diesel exhaust, but to what extent children are exposed to ultrafine particles (UFPs, diameter < 100 nm) in and around idling school buses remains unclear. This study employed nine school buses and simulated five scenarios by varying emissions source, wind direction, and window position. The purpose was to investigate the impact of idling on UFP number concentration and PM2.5 mass concentration inside and near school buses. Near the school buses, total particle number concentration increased sharply from engine off to engine on under all scenarios, by a factor of up to 26. The impact of idling on UFP number concentration inside the school buses depended on wind direction and window position: wind direction was important and statistically significant while the effect of window positions depended on wind direction. Under certain scenarios, idling increased in-cabin total particle number concentrations by a factor of up to 5.8, with the significant increase occurring in the size range of 10-30 nm. No significant change of in-cabin PM2.5 mass concentration was observed due to idling, regardless of wind direction and window position, indicating that PM2.5 is not a good indicator for primary diesel exhaust particle exposure. The deposition rates based on total particle number concentration inside school bus cabins varied between 1.5 and 5.0 h-1 across nine tested buses under natural convection conditions, lower than those of passenger cars but higher than those of indoor environments.

Optical gain characteristics of C 460 and C 450.

PubMed

Sharma, Vijay K; Sahare, P D; Pandey, A; Mohan, D

2003-03-15

Dye concentration dependent gain spectra for Coumarin 460 (C 460) and Coumarin 450 (C 450) in ethanol have been studied using Amplified Spontaneous Emission (ASE) technique under Nitrogen laser (337.1 nm) excitation in the concentration range 10(-2)-10(-5) m/l. The dependence of lasing wavelength and peak gain on concentration have been understood in terms of variation of fluorescence lifetime, which is due to photo-physical processes such as radiation trapping and concentration-quenching. Pump intensity dependence of efficiency is also explained in terms of fluorescence lifetime. A comparison of the stability of the two dyes has also been made on the basis of the functional groups at different positions of the basic coumarin. Copyright 2002 Elsevier Science B.V.

Combined effects of hydrographic structure and iron and copper availability on the phytoplankton growth in Terra Nova Bay Polynya (Ross Sea, Antarctica)

NASA Astrophysics Data System (ADS)

Rivaro, Paola; Luisa Abelmoschi, Maria; Grotti, Marco; Ianni, Carmela; Magi, Emanuele; Margiotta, Francesca; Massolo, Serena; Saggiomo, Vincenzo

2012-04-01

Surface water (<100 m) samples were collected from the Terra Nova Bay polynya region of the Ross Sea (Antarctica) in January 2006, with the aim of evaluating the individual and combined effects of hydrographic structure, iron and copper concentration and availability on the phytoplankton growth. The measurements were conducted within the framework of the Climatic Long Term Interaction for the Mass-balance in Antarctica (CLIMA) Project of the Programma Nazionale di Ricerca in Antartide activities. Dissolved oxygen, nutrients, phytoplankton pigments and concentration and complexation of dissolved trace metals were determined. Experimental data were elaborated by Principal Component Analysis (PCA). As a result of solar heating and freshwater inputs from melting sea-ice, the water column was strongly stratified with an Upper Mixed Layer 4-16 m deep. The integrated Chl a in the layer 0-100 m ranged from 60 mg m-2 to 235 mg m-2, with a mean value of 138 mg m-2. The pigment analysis showed that diatoms dominated the phytoplankton assemblage. Major nutrients were generally high, with the lowest concentration at the surface and they were never fully depleted. The Si:N drawdown ratio was close to the expected value of 1 for Fe-replete diatoms. We evaluated both the total and the labile dissolved fraction of Fe and Cu. The labile fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The total dissolved Fe ranged from 0.48 to 3.02 nM, while the total dissolved Cu from 3.68 to 6.84 nM. The dissolved labile Fe ranged from below the detection limit (0.15 nM) to 1.22 nM, and the dissolved labile Cu from 0.31 to 1.59 nM, respectively. The labile fractions measured at 20 m were significantly lower than values in 40-100 m samples. As two stations were re-sampled 5 days later, we evaluated the short-term variability of the physical and biogeochemical properties. In particular, in a re-sampled station at 20 m, the total dissolved Fe increased and the total dissolved Cu decreased, while their labile fraction was relatively steady. As a result of the increase in total Fe, the percentage of the labile Fe decreased. An increase of the Si:N, Si:P and Si:FUCO ratios was measured also in the re-sampled station. On this basis, we speculated that a switch from a Fe-replete to a Fe-deplete condition was occurring.

Optical properties of Dy3+ and Eu3+ -Codoped SrWO4 phosphors for white light-emitting diodes

NASA Astrophysics Data System (ADS)

Cho, Shinho

2018-01-01

Dy3+ - and Eu3+ -codoped SrWO4 phosphor powders were prepared using a solid-state reaction technique by changing the molar concentration of Eu3+ within the range of 0 to 15 mol% at a fixed Dy3+ concentration of 5 mol%. The effects of Dy3+ and Eu3+ doping on the structural, morphological, and optical properties of SrWO4:Dy3+, Eu3+ phosphors were investigated via Xray diffraction, scanning electron microscopy, and photoluminescence spectrophotometry, respectively. Irrespective of the concentrations of Dy3+ and Eu3+ ions, the crystal structures of all the phosphors were tetragonal, and the grains exhibited a tendency to agglomerate. The emission spectra of Sr0.925WO4:5 mol% Dy3+ contained an intense yellow band at 573 nm arising from the 4 F 9/2 → 6 H 13/2 electric dipole transition of Dy3+, as well as three weak emission lines. When the Eu3+ ions were incorporated into the SrWO4:Dy3+ phosphors, a strong red emission peak at 615 nm originating from the 5D0 → 7F2 transition of Eu3+ appeared in addition to the four emission bands centered at 481, 573, 662, and 750 nm, which result from the 4 f-4 f transitions of Dy3+. The emission intensity decreased as the Eu3+ concentration increased up to 15 mol% due to concentration quenching, which resulted from dipole-dipole interactions. The results suggest that the color emissions and intensities of SrWO4:Dy3+, Eu3+ phosphors can be tuned from yellow to white to red by varying the types of ions used and the ratio of Dy3+ to Eu3+ ions.

Dilution effects on ultrafine particle emissions from Euro 5 and Euro 6 diesel and gasoline vehicles

NASA Astrophysics Data System (ADS)

Louis, Cédric; Liu, Yao; Martinet, Simon; D'Anna, Barbara; Valiente, Alvaro Martinez; Boreave, Antoinette; R'Mili, Badr; Tassel, Patrick; Perret, Pascal; André, Michel

2017-11-01

Dilution and temperature used during sampling of vehicle exhaust can modify particle number concentration and size distribution. Two experiments were performed on a chassis dynamometer to assess exhaust dilution and temperature on particle number and particle size distribution for Euro 5 and Euro 6 vehicles. In the first experiment, the effects of dilution (ratio from 8 to 4 000) and temperature (ranging from 50 °C to 150 °C) on particle quantification were investigated directly from tailpipe for a diesel and a gasoline Euro 5 vehicles. In the second experiment, particle emissions from Euro 6 diesel and gasoline vehicles directly sampled from the tailpipe were compared to the constant volume sampling (CVS) measurements under similar sampling conditions. Low primary dilutions (3-5) induced an increase in particle number concentration by a factor of 2 compared to high primary dilutions (12-20). Low dilution temperatures (50 °C) induced 1.4-3 times higher particle number concentration than high dilution temperatures (150 °C). For the Euro 6 gasoline vehicle with direct injection, constant volume sampling (CVS) particle number concentrations were higher than after the tailpipe by a factor of 6, 80 and 22 for Artemis urban, road and motorway, respectively. For the same vehicle, particle size distribution measured after the tailpipe was centred on 10 nm, and particles were smaller than the ones measured after CVS that was centred between 50 nm and 70 nm. The high particle concentration (≈106 #/cm3) and the growth of diameter, measured in the CVS, highlighted aerosol transformations, such as nucleation, condensation and coagulation occurring in the sampling system and this might have biased the particle measurements.

Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor

PubMed Central

Mehmood, Shahid; Ciancio, Regina; Carlino, Elvio; Bhatti, Arshad S

2018-01-01

Background The combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution. Methods In this work, the charge transfer kinetics in the glassy carbon electrode (GCE) modified with Au(NPs)–multiwalled carbon nanotube (MWCNT) nanohybrid with varied concentrations of Au(NPs) in the range 40–100 nM was studied using electrochemical impedance spectroscopy (EIS). Field emission scanning electron microscopy and transmission electron microscopy confirmed the attachment of Au(NPs) on the surface of MWCNTs. Results The cyclic voltammetry and EIS results showed that the charge transfer mechanism was diffusion controlled and the rate of charge transfer was dependent on the concentration of Au(NPs) in the nanohybrid. The formation of spherical diffusion zone, which was dependent on the concentration of Au(NPs) in nanohybrids, was attributed to result in 3 times the increase in the charge transfer rate ks, 5 times increase in mass transfer, and 5% (9%) increase in Ipa (Ipc) observed in cyclic voltammetry in 80 nM Au(NP) nanohybrid-modified GCE from MWCNT-modified GCE. The work was extended to probe the effect of charge transfer rates at various concentrations of Au(NPs) in the nanohybrid-modified electrodes in the presence of Escherichia coli. The cyclic voltammetry results clearly showed the best results for 80 nM Au(NPs) in nanohybrid electrode. Conclusion The present study suggested that the formation of spherical diffusion zone in nanohybrid-modified electrodes is critical for the enhanced electrochemical biosensing applications. PMID:29713161

Characterization and antibacterial properties of stable silver substituted hydroxyapatite nanoparticles synthesized through surfactant assisted microwave process

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

Iqbal, Nida; Abdul Kadir, Mohammed Rafiq, E-mail: rafiq@biomedical.utm.my; Nik Malek, Nik Ahmad Nazim

Highlights: • Stable nano sized silver substitute hydroxyapatite is prepared under surfactant assisted microwave process at 600 W power for 7 min. • The nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. • Increase in silver concentration resulted in better dielectric properties. • Good antibacterial activity and silver release. - Abstract: The present study reports a relatively simple method for the synthesis of stable silver substituted hydroxyapatite nanoparticles with controlled morphology and particle size. In order to achieve this, CTAB is included as a surfactant in the microwave refluxing process (600 W formore » 7 min). The nanoparticles produced with different silver ion concentrations (0.05, 0.1 and 0.2 wt%) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX) and Brunauer–Emmett–Teller (BET) analysis. XRD and FTIR analyses reveal that the Ag-HA nanoparticles were phase pure at 1000 °C. FESEM images showed that the produced nanoparticles are in the size range of 58–72 nm and exert uniform elongated spheroid morphology. The dielectric properties suggest that the increase in dielectric constant (ε′) and dissipation factor (D) values with increasing Ag concentrations. Antibacterial performance of the Ag-HA samples elucidated using disk diffusion technique (DDT) and minimum inhibitory concentration (MIC) demonstrates anti-bacterial activity against Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli. This effect was dose dependent and was more pronounced against Gram-negative bacteria than Gram-positive organisms.« less

Efficient in vitro photodynamic inactivation of Candida albicans by repetitive light doses

NASA Astrophysics Data System (ADS)

Torres-Hurtado, S. A.; Ramírez Ramírez, J.; Ramos-García, R.; Ramírez-San-Juan, J. C.; Spezzia-Mazzocco, T.

2018-02-01

The aim of this study was to compare the effectiveness of Rose Bengal (RB) and Methylene Blue (MB) as photosensitizers (PS) in Photodynamic Inactivation (PDI) on planktonic cultures of Candida albicans, a well-known opportunistic pathogen. RB and MB at concentrations ranging from 0.5 to 60 μM and fluences of 10, 30, 45 and 60 J/cm2 were tested. The light sources consist of an array of 12 led diodes with 30 mW of optical power each; 490-540 nm (green light) to activate RB and 600 -650 nm (red light) to activate MB. We first optimize the in vitro PDI technique using a single light dose and the optimum PS concentration. The novelty of our approach consist in reducing further the PS concentration than the optimum obtained with a single light exposure and using smaller light fluence doses by using repetitive light exposures (two to three times). MB and RB were tested for repetitive exposures at concentrations ranging from 0.1 to 10 μM, with fluences of 3 to 20 J/cm2, doses well below than those reported previously. All experiments were done in triplicate with the corresponding controls; cells without treatment, light control and dark toxicity control. RB-PDI and MB-PDI significantly reduced the number of CFU/mL when compared to the control groups. The results showed that RB was more effective than MB for C. albicans inactivation. Thus, we show that is possible to reduce significantly the amount of PS and light fluence requirements using repetitive light doses of PDI in vitro.

Potential for Occupational Exposure to Engineered Carbon-Based Nanomaterials in Environmental Laboratory Studies

PubMed Central

Johnson, David R.; Methner, Mark M.; Kennedy, Alan J.; Steevens, Jeffery A.

2010-01-01

Background The potential exists for laboratory personnel to be exposed to engineered carbon-based nanomaterials (CNMs) in studies aimed at producing conditions similar to those found in natural surface waters [e.g., presence of natural organic matter (NOM)]. Objective The goal of this preliminary investigation was to assess the release of CNMs into the laboratory atmosphere during handling and sonication into environmentally relevant matrices. Methods We measured fullerenes (C60), underivatized multiwalled carbon nanotubes (raw MWCNT), hydroxylated MWCNT (MWCNT-OH), and carbon black (CB) in air as the nanomaterials were weighed, transferred to beakers filled with reconstituted freshwater, and sonicated in deionized water and reconstituted freshwater with and without NOM. Airborne nanomaterials emitted during processing were quantified using two hand-held particle counters that measure total particle number concentration per volume of air within the nanometer range (10–1,000 nm) and six specific size ranges (300–10,000 nm). Particle size and morphology were determined by transmission electron microscopy of air sample filters. Discussion After correcting for background particle number concentrations, it was evident that increases in airborne particle number concentrations occurred for each nanomaterial except CB during weighing, with airborne particle number concentrations inversely related to particle size. Sonicating nanomaterial-spiked water resulted in increased airborne nanomaterials, most notably for MWCNT-OH in water with NOM and for CB. Conclusion Engineered nanomaterials can become airborne when mixed in solution by sonication, especially when nanomaterials are functionalized or in water containing NOM. This finding indicates that laboratory workers may be at increased risk of exposure to engineered nanomaterials. PMID:20056572

T1 relaxivity of core-encapsulated gadolinium liposomal contrast agents--effect of liposome size and internal gadolinium concentration.

PubMed

Ghaghada, Ketan; Hawley, Catherine; Kawaji, Keigo; Annapragada, Ananth; Mukundan, Srinivasan

2008-10-01

Long circulating core-encapsulated gadolinium (CE-Gd) liposomal nanoparticles that have surface conjugated polyethylene glycol are a promising platform technology for use as blood pool T1-based magnetic resonance (MR) contrast agents. The objective of this study was to investigate the effect of liposome size and internal (core) Gd concentration on the T1 relaxivity of CE-Gd liposomes. Twelve different liposomal formulations were synthesized and characterized, resulting in a size (50, 100, 200, and 400 nm) and core Gd-concentration (200, 350, and 500 mM) "matrix" of test samples. Subsequently, CE-Gd liposomes were diluted in deionized water (four diluted samples) and molar T1 relaxivity (r1) measurements were performed at 2- and 7-T MR field strengths. The r1 of CE-Gd liposomes was inversely related to the liposome size. The largest change in r1 was observed between liposomes that were extruded through 50- and 100-nm filter membranes. At both field strengths, the variation in internal gadolinium concentration did not show any significant correlation (alpha < or = 0.05) with r1. The size of CE-Gd liposomal nanoparticles significantly affects the T1 relaxivity. An inverse relation was observed between liposome size and T1 relaxivity. The T1 relaxivity did not change significantly with core Gd concentration over the measured concentration range.

Chromatographic determination of nanomolar cyanate concentrations in estuarine and sea waters by precolumn fluorescence derivatization.

PubMed

Widner, Brittany; Mulholland, Margaret R; Mopper, Kenneth

2013-07-16

Recent studies suggest that cyanate (OCN(-)) is a potentially important source of reduced nitrogen (N) available to support the growth of aquatic microbes and, thus, may play a role in aquatic N cycling. However, aquatic OCN(-) distributions have not been previously described because of the lack of a suitable assay for measuring OCN(-) concentrations in natural waters. Previous methods were designed to quantify OCN(-) in aqueous samples with much higher reduced N concentrations (micromolar levels) than those likely to be found in natural waters (nanomolar levels). We have developed a method to quantify OCN(-) in dilute, saline environments. In the method described here, OCN(-) in aqueous solution reacts with 2-aminobenzoic acid to produce a highly fluorescent derivative, 2,4-quinazolinedione, which is then quantified using high performance liquid chromatography. Derivatization conditions were optimized to simultaneously minimize the reagent blank and maximize 2,4-quinazolinedione formation (>90% reaction yield) in estuarine and seawater matrices. A limit of detection (LOD) of 0.4 nM was achieved with only minor matrix effects. We applied this method to measure OCN(-) concentrations in estuarine and seawater samples from the Chesapeake Bay and coastal waters from the mid-Atlantic region. OCN(-) concentrations ranged from 0.9 to 41 nM. We determined that OCN(-) concentrations were stable in 0.2 μm filtered seawater samples stored at -80 °C for up to nine months.

Dry deposition of ammonia, nitric acid, ammonium, and nitrate to alpine tundra at Niwot Ridge, Colorado

USGS Publications Warehouse

Rattray, G.; Sievering, H.

2001-01-01

Micrometeorological measurements and ambient air samples, analyzed for concentrations of NH3, HNO3, NH4+, and NO3-, were collected at an alpine tundra site on Niwot Ridge, Colorado. The measured concentrations were extremely low and ranged between 5 and 70ngNm-3. Dry deposition fluxes of these atmospheric species were calculated using the micrometeorological gradient method. The calculated mean flux for NH3 indicates a net deposition to the surface and indicates that NH3 contributed significantly to the total N deposition to the tundra during the August-September measurement period. Our pre-measurement estimate of the compensation point for NH3 in air above the tundra was 100-200ngNm-3; thus, a net emission of NH3 was expected given the low ambient concentrations of NH3 observed. Based on our results, however, the NH3 compensation point at this alpine tundra site appears to have been at or below about 20ngNm-3. Large deposition velocities (>2cms-1) were determined for nitrate and ammonium and may result from reactions with surface-derived aerosols. Copyright (C) 2001 Elsevier Science B.V.Micrometeorological measurements and ambient air samples, analyzed for concentrations of NH3, HNO3, NH4+, and NO3-, were collected at an alpine tundra site on Niwot Ridge, Colorado. The measured concentrations were extremely low and ranged between 5 and 70 ng N m-3. Dry deposition fluxes of these atmospheric species were calculated using the micrometeorological gradient method. The calculated mean flux for NH3 indicates a net deposition to the surface and indicates that NH3 contributed significantly to the total N deposition to the tundra during the August-September measurement period. Our pre-measurement estimate of the compensation point for NH3 in air above the tundra was 100-200 ng N m-3; thus, a net emission of NH3 was expected given the low ambient concentrations of NH3 observed. Based on our results, however, the NH3 compensation point at this alpine tundra site appears to have been at or below about 20 ng N m-3. Large deposition velocities (>2 cm s-1) were determined for nitrate and ammonium and may result from reactions with surface-derived aerosols.

Photometric flow injection determination of phosphate on a PDMS microchip using an optical detection system assembled with an organic light emitting diode and an organic photodiode.

PubMed

Liu, Rong; Ishimatsu, Ryoichi; Yahiro, Masayuki; Adachi, Chihaya; Nakano, Koji; Imato, Toshihiko

2015-01-01

A compact photometric detector was constructed from an organic light emitting diode (OLED) based on a europium complex, europium(diben-zoylmethanato)3(bathophenanthroline) (Eu(DBM)3bath), as the light source and an organic photodiode (OPD) fabricated from a hetero-junction of two layers of copper phthalocyanine (CuPc)/fullerene (C60) as the photo-detector on a microchip prepared from poly(dimethylsiloxan) (PDMS) and was applied to the determination of phosphate. The OLED and the OPD were fabricated by a vapor deposition method on an indium tin oxide (ITO) coated glass substrate with the following layered structure; Glass (0.7 mm)/ITO (110 nm)/4,4'-bis[N-(1-naphthyl)-N-phenyl amino]-biphenyl (α-NPD) (30 nm)/4,4'-di(N-carbazolyl)biphenyl (CBP): Eu(3+) (8 wt%, 30 nm)/bathocuproine (BCP) (30 nm)/aluminum tris(8-hydroxyquinoline) (Alq3) (25 nm)/magnesium and silver (MgAg) (100 nm)/Ag (10nm) and Glass (0.7 mm)/ITO (110 nm)/CuPc (35 nm)/C60 (50 nm)/BCP (10 nm)/Ag (50 nm), respectively. The OLED based on the europium complex emitted a sharp light at the wavelength of 612 nm with a full width at half maximum (FWHM) of 8 nm. The performance of the photometric detector assembled was evaluated based on measurements of the absorbance of different concentrations of malachite green (MG) solutions for a batch system with 1cm long path length. The molar absorptive coefficient of the MG solution, calculated from the photocurrent of the OPD, was in good agreement with the value reported in the literature. A microchip with two inlets and one outlet U-shaped channel was prepared by a conventional photolithograph method. The OLED and the OPD were configured so as to face each other through the PDMS microchip in parallel in order to align the light axis of the OLED and the OPD with the flow cell (optical path length of 5mm), which was located at the end of outlet. For the determination of phosphate, an ion-association reaction between MG and a molybdenum-phosphate complex was utilized and a good linear relationship between the concentration and absorbance was observed in the concentration range 0-0.2 ppm, with a detection limit (S/N=3) of 0.02 ppm. The assembled photometric detector was also applied to the determination of phosphate by the flow injection of river water samples using the reagent solution containing MG and molybdenum ammonium in sulfuric acid. A good recovery (97-99%) for the river water samples, which had been spiked with the standard 0.08 ppm, with an RSD of ca 5% (n=5) was obtained using the constructed system. Copyright © 2014 Elsevier B.V. All rights reserved.

Absorption and scattering properties of organic carbon vs. sulfate dominant aerosols at Gosan climate observatory in Northeast Asia

NASA Astrophysics Data System (ADS)

Lim, S.; Lee, M.; Kim, S.-W.; Yoon, S.-C.; Lee, G.; Lee, Y.

2013-12-01

Carbonaceous and soluble ionic species of PM1.0 and PM10 were measured along with the absorption and scattering properties and aerosol number size distributions at Gosan climate observatory (GCO) from January to September 2008. The daily averaged equivalent black carbon (EBC) measured as aerosol absorption exhibited two types of spectral dependence with a distinct maximum (peak) at either 370 nm or 880 nm, by which two subsets were extracted and classified into the respective groups (370 nm and 880 nm). The 370 nm group was distinguished by high organic carbon (OC) concentrations relative to elemental carbon (EC) and sulfate, but sulfate was predominant for the 880 nm group. The PM1.0 OC of the 370 nm group was mainly composed of refractory and pyrolized components that correlated well with PM1.0 EC1, referred to as char EC, which suggests biofuel and biomass combustion as the source of these OC fractions, particularly during winter. The scanning electron microscope (SEM) images and the number size distributions implied that aerosols of the 370 nm group were externally mixed upon transport in fast-moving air masses that passed through the Beijing area in about one day. In contrast, the aerosols of the 880 nm group were characterized by high sulfate concentrations, and seemed to be internally mixed during slow transport over the Yellow Sea region over approximately two to four days. The absorption and scattering coefficients of the 880 nm group were noticeably higher compared to those of the 370 nm group. The average absorption ångström exponent (AAE) was estimated to be 1.29 and 1.0 for the 370 nm and 880 nm groups, respectively, in the range 370-950 nm. These results demonstrated that the optical properties of aerosols were intimately linked to chemical composition and mixing state, characteristics determined both by source and atmospheric aging processes. In OC dominant aerosols, absorption was enhanced in the UV region, which was possibly due to refractory and pyrolized OC compounds. Under sulfate dominant conditions, the sulfate coating on BC particles contributed to the absorption of the longer visible light. Consequently, single scattering albedo (SSA) was higher for the 880 nm group than for the 370 nm group, emphasizing that the relative abundances of absorbing and scattering constituents are also important in estimating the climate effect of aerosols.

Aerosol mixingstate, hygroscopic growth and cloud activation efficiency during MIRAGE 2006

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

Lance, Sara; Raatikainen, T.; Onasch, Timothy B.

2013-05-15

Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. K¨ohler theory is used to evaluate the characteristic water uptake coefficient, k*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions, (forg), are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which kAMS is inferred and compared against k*. Strong diurnal profiles of aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated withmore » an increased k* and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN can surpass by more than a factor of two the concentrations of 100 nm particles acting as CCN, at supersaturations of 0.51% +/- 0.06%. We also find that at 0600-0800 in the morning throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally-mixed fraction for 40 nm particles and 30% externally-mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as “internally-mixed”. Average activation spectra and growth factor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning “rush hour”, and the entire campaign. We show that k* derived from CCNc measurements decreases as a function of size during all time periods, while the CCN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for k* versus particle size, which can be attributed to unresolved mixing-state and the presence of refractory material not measured by the AMS. Measured k* typically ranges from 0.2 to 0.35, and organics typically make up 60-85% of the aerosol mass in the size range studied. Despite some disagreement between kAMS and kCCNc, we show that kAMS is able to describe CCN concentrations reasonably well, especially at the highest CCN concentrations. This is consistent with other CCN studies carried out in urban environments, and is partly due to the fact that the highest CCN concentrations occur during the daytime when the aerosol is internally-mixed and the organic fraction is relatively low. During the early morning rush hour, however, failing to account for the aerosol mixing state results in systematic overestimation of CCN concentrations by 50-100%.« less

Optical properties of breast tumor phantoms containing carbon nanotubes and nanohorns

PubMed Central

Sarkar, Saugata; Gurjarpadhye, Abhijit A.; Rylander, Christopher G.; Nichole Rylander, Marissa

2011-01-01

The degree by which optical properties of tumors are altered following introduction of carbon nanotubes (CNTs) of varying concentration and type is poorly understood, making it difficult to predict the impact of CNT inclusion on the photothermal response to laser therapies. Optical properties were measured of phantoms representative of breast tumor tissue incorporated with multiwalled carbon nanotubes (MWNTs), single-walled carbon nanotubes (SWNTs), and single-walled carbon nanohorns (SWNHs) of varying concentration (0.01–0.1 mg/ml). Tissue phantoms were made from sodium alginate (3 g/ml) incorporated with polystyrene microbeads (3 μm diam and 1 mg/ml) and talc-France powder (40 mg/ml). Absorption (μa) and reduced scattering (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\mu^\\prime _s\\end{equation*} \\end{document}μs′) coefficients of phantoms containing CNTs were determined by the inverse adding-doubling algorithm for the wavelength range of 400–1300 nm. Optical properties of phantoms without CNTs were in the range of μa = 1.04–0.06 mm−1 and \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\mu^\\prime _s\\end{equation*} \\end{document}μs′ = 0.05–0.07 mm−1 at a wavelength of 900 nm, which corresponds with published data for human breast tumor tissue. Incorporating MWNTs, SWNTs, and SWNHs in phantoms with a concentration of 0.1 mg/ml increased (μa) by 20- to 30-fold, 5- to 6-fold, and 9- to 14-fold, respectively, for the wavelength range of 800–1100 nm with minimal change in \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\mu^\\prime _s\\end{equation*} \\end{document}μs′ (1.2- to 1.3-fold). Introduction of CNTs into tissue phantoms increased absorption, providing a means to enhance photothermal therapy. PMID:21639564

Four-dimensional approach to simultaneous analysis of urban fine aerosols and three different meteorological parameters

NASA Astrophysics Data System (ADS)

Hejkrlík, Libor; Plachá, Helena

2017-04-01

Number concentrations of fine particles had been measured by SMPS in a diameter range of 10 to 800 nm in 7 channels with time resolution of one hour since June 2012 to December 2015 at a background urban site in Northern Bohemia. At nearly the same place hourly means of three meteorological elements were available (air temperature Th, relative air humidity Hh and global radiation Rh) and as a complementary index of atmospheric pollution the mass concentrations of PM1-BC (black carbon). The whole period of observations covered 1309 days, periodically involving all of the seasons of the year. Th varied between 11,2 ˚ C and 36,1 ˚ C, for Hh it was between 21% and 100% and Rh reached its extremes between 0,2 and 940,5 W/m2 (night hours were excluded). Resulting number of analyzed rows of 11 variables was approximately 14 000. The nearly-continuous combinations of meteorological data were transformed into three-dimensional matrix where Th,Hh and Rh were assigned only few discrete values (48, 13 and 13 respectively). In the cells of the 3D matrix mean concentrations of different modes of fine particles and of PM1-BC were calculated. The results were displayed in the form of XYZ bubble graph, diameters of the spheres being the fourth dimension. The results offer insight into relation between sub-micron particles concentrations and meteorological conditions on parallel time basis. The nucleation mode of nanoparticles (10-30 nm) demonstrate strong proliferation (N˜104/cm3/hour) under extreme both temperature and solar radiation while air moisture remains moderate. The effect is less obvious for Aitken mode (30-70 nm) and fades gradually away for fine particles (100-800 nm, N˜103/cm3/hour). Particles PM1-BC (≤ 1000 nm, Cm ˜1 μg/m3/hour), measured by MAAP, show considerable affinity to low visibility and high humidity but the overall picture persists, what may serve as a proof of equivalence of the measuring procedures.

Characterizing ultrafine particles and other air pollutants in and around school buses.

PubMed

Zhu, Yifang; Zhang, Qunfang

2014-03-01

Increasing evidence has demonstrated toxic effects of ultrafine particles (UFP*, diameter < 100 nm). Children are particularly at risk because of their immature respiratory systems and higher breathing rates per body mass. This study aimed to characterize UFP, PM2.5 (particulate matter < or = 2.5 microm in aerodynamic diameter), and other vehicular-emitted pollutants in and around school buses. Four sub-studies were conducted, including: 1. On-road tests to measure in-cabin air pollutant levels while school buses were being driven; 2. Idling tests to determine the contributions of tailpipe emissions from idling school buses to air pollutant levels in and around school buses under different scenarios; 3. Retrofit tests to evaluate the performance of two retrofit systems, a diesel oxidation catalyst (DOC) muffler and a crankcase filtration system (CFS), on reducing tailpipe emissions and in-cabin air pollutant concentrations under idling and driving conditions; and 4. High efficiency particulate air (HEPA) filter air purifier tests to evaluate the effectiveness of in-cabin filtration. In total, 24 school buses were employed to cover a wide range of school buses commonly used in the United States. Real-time air quality measurements included particle number concentration (PNC), fine and UFP size distribution in the size range 7.6-289 nm, PM2.5 mass concentration, black carbon (BC) concentration, and carbon monoxide (CO) and carbon dioxide (CO2) concentrations. For in-cabin measurements, instruments were placed on a platform secured to the rear seats inside the school buses. For all other tests, a second set of instruments was deployed to simultaneously measure the ambient air pollutant levels. For tailpipe emission measurements, the exhaust was diluted and then measured by instruments identical to those used for the in-cabin measurements. The results show that when driving on roads, in-cabin PNC, fine and UFP size distribution, PM2.5, BC, and CO varied by engine age, window position, driving speed, driving route, and operating conditions. Emissions from idling school buses increased the PNC close to the tailpipe by a factor of up to 26.0. Under some circumstances, tailpipe emissions of idling school buses increased the in-cabin PNC by factors ranging from 1.2 to 5.8 in the 10-30 nm particle size range. Retrofit systems significantly reduced the tailpipe emissions of idling school buses. With both DOC and CFS installed, PNC in tailpipe emissions dropped by 20%-94%. No unequivocal decrease was observed for in-cabin air pollutants after retrofitting. The operation of the air conditioning (AC) unit and the pollutant concentrations in the surrounding ambient air played more important roles than retrofit technologies in determining in-cabin air quality. The use of a HEPA air purifier removed up to 50% of in-cabin particles. Because each sub-study tested only a subset of the 24 school buses, the results should be seen as more exploratory than definitive.