Effects of ionic concentration gradient on electroosmotic flow mixing in a microchannel.

PubMed

Peng, Ran; Li, Dongqing

2015-02-15

Effects of ionic concentration gradient on electroosmotic flow (EOF) mixing of one stream of a high concentration electrolyte solution with a stream of a low concentration electrolyte solution in a microchannel are investigated numerically. The concentration field, flow field and electric field are strongly coupled via concentration dependent zeta potential, dielectric constant and electric conductivity. The results show that the electric field and the flow velocity are non-uniform when the concentration dependence of these parameters is taken into consideration. It is also found that when the ionic concentration of the electrolyte solution is higher than 1M, the electrolyte solution essentially cannot enter the channel due to the extremely low electroosmotic flow mobility. The effects of the concentration dependence of zeta potential, dielectric constant and electric conductivity on electroosmotic flow mixing are studied. Copyright © 2014 Elsevier Inc. All rights reserved.

Characterization of Nanoparticles and Colloids in Aquatic Systems 1. Small Angle Neutron Scattering Investigations of Suwannee River Fulvic Acid Aggregates in Aqueous Solutions

NASA Astrophysics Data System (ADS)

Diallo, Mamadou S.; Glinka, Charles J.; Goddard, William A.; Johnson, James H.

2005-10-01

Fulvic acids (FA) and humic acids (HA) constitute 30-50% of dissolved organic matter in natural aquatic systems. In aqueous solutions, a commonly accepted view is that FA and HA exist as soluble macroligands at low concentration and as supramolecular aggregates at higher concentration. The size, shape and structure of these aggregates are still the subject of ongoing debate in the environmental chemistry literature. In this article, we use small angle neutron scattering (SANS) to assess the effects of solute concentration, solution pH and background electrolyte (NaCl) concentration on the structures of Suwannee River FA (SRFA) aggregates in D2O. The qualitative features of the SANS curves and data analysis are not consistent with the view point that SRFA forms micelle-like aggregates as its concentration in aqueous solution increases. We find that SRFA forms fractal aggregates in D20 with size greater than 242 nm. The SRFA aggregates undergo a significant degree of restructuring in compactness as solution pH, solute concentration and NaCl concentration increase.

Factors contributing to inactivation of isolated thylakoid membranes during freezing in the presence of variable amounts of glucose and NaCl.

PubMed Central

Santarius, K A; Giersch, C

1984-01-01

During freezing of isolated spinach thylakoids in sugar/salt solutions, the two solutes affected membrane survival in opposite ways: membrane damage due to increased electrolyte concentration can be prevented by sugar. Calculation of the final concentrations of NaCl or glucose reached in the residual unfrozen portion of the system revealed that the effects of the solutes on membrane activity can be explained in part by colligative action. In addition, the fraction of the residual liquid in the frozen system contributes to membrane injury. During severe freezing in the presence of very low initial solute concentrations, membrane damage drastically increased with a decrease in the volume of the unfrozen solution. Freezing injury under these conditions is likely to be due to mechanical damage by the ice crystals that occupy a very high fraction of the frozen system. At higher starting concentrations of sugar plus salt, membrane damage increased with an increase in the amount of the residual unfrozen liquid. Thylakoid inactivation at these higher initial solute concentrations can be largely attributed to dilution of the membrane fraction, as freezing damage at a given sugar/salt ratio decreased with increasing the thylakoid concentration in the sample. Moreover, membrane survival in the absence of freezing decreased with lowering the temperature, indicating that the temperature affected membrane damage not only via alterations related to the ice formation. From the data it was evident that damage of thylakoid membranes was determined by various individual factors, such as the amount of ice formed, the final concentrations of solutes and membranes in the residual unfrozen solution, the final volume of this fraction, the temperature and the freezing time. The relative contribution of these factors depended on the experimental conditions, mainly the sugar/salt ratio, the initial solute concentrations, and the freezing temperature. PMID:6478028

Expression of Geochemical Controls on Water Quality in Loch Vale, Rocky Mountain National Park

NASA Astrophysics Data System (ADS)

Podzorski, H.; Navarre-Sitchler, A.; Stets, E.; Clow, D. W.

2017-12-01

Relationships between concentrations of rock weathering products and discharge provide insight into the interactions between climate and solute dynamics. This concentration-discharge (C-Q) relationship is especially interesting in high alpine regions, due to their susceptibility to changes in the timing and magnitude of snowmelt. Previous studies looking at C-Q relationships have concluded that concentrations of conservative solutes remain relatively constant as discharge varies; however, these results may be due to relatively small sample sizes, especially at higher discharge values. Using water chemistry data collected regularly by the U.S. Geological Survey from Loch Vale, a high-elevation catchment in Rocky Mountain National Park, C-Q relationships were examined to determine possible geochemical controls on stream solute concentrations. A record of over 20 years of C-Q data resulted in a pattern that shows little variation in conservative solute concentrations during base flow and larger variations in concentrations around peak discharge. This observed pattern is consistent with accumulation of solutes in pore water during base flow, which are then flushed out and diluted by snowmelt. Further evidence of this flushing out mechanism is found in patterns of hysteresis that are present in annual C-Q relationships. Before peak discharge, concentrations of weathering products are higher than after peak discharge at similar values of discharge. Based on these observations, we hypothesize that the geochemical processes controlling stream chemistry vary by season. During the winter, solute concentrations are transport-limited due to slow subsurface flushing resulting in concentrations that are effectively constant and close to equilibrium. During the spring and summer, concentrations drop sharply after peak discharge due to a combination of dilution and reaction-limited processes under conditions with faster subsurface flow and continued snowmelt. This study provides insight into seasonal geochemical controls on conservative solute concentrations that can be overlooked with small, or seasonally biased, data sets.

Influence of Concentration and Agitation of Sodium Hypochlorite and Peracetic Acid Solutions on Tissue Dissolution.

PubMed

Tanomaru-Filho, Mário; Silveira, Bruna Ramos Franco; Martelo, Roberta Bosso; Guerreiro-Tanomaru, Juliane Maria

2015-11-01

To evaluated the tissue dissolution of sodium hypochlorite (NaOCl) and peracetic acid (PA) solutions at different concentrations, with or without ultrasonic agitation. The following solutions were analyzed: 2.5% NaOCl, 0.5, 1 and 2% PA, 1% PA associated with 6.5% hydrogen peroxide (HP) and saline. Fragments of bovine pulp tissue with 25 ± 2g mg were immersed into test tubes containing 4 mL of the solutions for 10 minutes. In the groups with agitation, pulp tissues were submitted to 2 cycles of 1 minute of ultrasonic agitation. The specimens were weighed after the removal from the solutions. The percentage of mass loss was calculated according to the difference of mass before and after exposure to solutions. Data were submitted to ANOVA and Tukey tests (p < 0.05). A total of 2.5% NaOCl with or without agitation showed the higher tissue dissolution (between 64.5 and 67% of mass reduction) (p < 0.005). By comparing the PA solutions, the concentrations of 1 and 2% with or without agitation and the concentration of 0.5% with agitation showed similar dissolution activity (between 35.4 and 44% of mass reduction). The use of the ultrasonic agitation promoted an increase of the dissolution ability only for 0.5% PA. Peracetic acid solution has pulp tissue dissolution. However, this ability is lower than 2.5% NaOCl solution. The sodium hypochlorite solution shows higher ability to dissolve tissue than PA.

Soil Solution Phosphorus Status and Mycorrhizal Dependency in Leucaena leucocephala.

PubMed

Habte, M; Manjunath, A

1987-04-01

A phosphorus sorption isotherm was used to establish concentrations of P in a soil solution ranging from 0.002 to 0.807 mug/ml. The influence of P concentration on the symbiotic interaction between the tropical tree legume Leucaena leucocephala and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum was evaluated in pot experiments. The level of mycorrhizal infection in Leucaena roots increased as the concentration of P was raised from 0.002 to 0.153 mug/ml. Higher levels of P depressed mycorrhizal infection, but the level of infection never declined below 50%. Periodic monitoring of P contents of Leucaena subleaflets indicated that significant mycorrhizal activity was detected as early as 17 days after planting, with the activity peaking 12 to 16 days thereafter. The highest level of mycorrhizal activity was associated with a soil solution P level of 0.021 mug/ml. Even though the mycorrhizal inoculation effect diminished as the concentration of P in the soil solution was increased, mycorrhizal inoculation significantly increased P uptake and dry-matter yield of Leucaena at all levels of soil solution P examined. The concentration of P required by nonmycorrhizal L. leucocephala for maximum yield was 27 to 38 times higher than that required by mycorrhizal L. leucocephala. The results illustrate the very high dependence of L. leucocephala on VAM fungi and the significance of optimizing soil solution phosphorus for enhancing the benefits of the VAM symbiosis.

Significant alteration of Critical Zone processes in urban watersheds: shifting from a transport-limited to a weathering-limited regime

NASA Astrophysics Data System (ADS)

Moore, J.; Bird, D. L.; Dobbis, S. K.; Woodward, G.

2016-12-01

Urban areas and associated impervious surface cover (ISC) are among the fastest growing land use types. Rapid growth of urban lands has significant implications for geochemical cycling and solute sources to streams, estuaries, and coastal waters. However, little work has been done to investigate the impacts of urbanization on Critical Processes, including on the export of solutes from urban watersheds. Despite observed elevated solute concentrations in urban streams in some previous studies, neither solute sources nor total solute fluxes have been quantified due to mixed bedrock geology, lack of a forested reference watershed, or the presence of point sources that confounded separation of anthropologic and natural sources. We investigated the geochemical signal of the urban built environment (e.g., roads, parking lots, buildings) in a set of five USGS-gaged watersheds across a rural (forested) to urban gradient in the Maryland Piedmont. These watersheds have ISC ranging from 0 to 25%, no point sources, and similar felsic bedrock chemistry. Weathering from the urban built environment and ISC produces dramatically higher solute concentrations in urban watersheds than in the forested watershed. Higher solute concentrations result in chemical weathering fluxes from urban watersheds that are 11-13 times higher than the forested watershed and are similar to fluxes from mountainous, weathering-limited watersheds rather than fluxes from transport-limited, dilute streams like the forested watershed. Weathering of concrete in urban watersheds produces geochemistry similar to weathering-limited watersheds with high concentrations of Ca2+, Mg2+, and DIC, which is similar to stream chemistry due to carbonate weathering. Road salt dissolution results in high Na+ and Cl- concentrations similar to evaporite weathering. Quantifying processes causing elevated solute fluxes from urban areas is essential to understanding cycling of Ca2+, Mg2+, and DIC in urban streams and in downgradient estuarine or coastal waters.

Seasonal dynamics of groundwater-lake interactions at Doñana National Park, Spain

USGS Publications Warehouse

Sacks, Laura A.; Herman, Janet S.; Konikow, Leonard F.; Vela, Antonio L.

1992-01-01

The hydrologic and solute budgets of a lake can be strongly influenced by transient groundwater flow. Several shallow interdunal lakes in southwest Spain are in close hydraulic connection with the shallow ground water. Two permanent lakes and one intermittent lake have chloride concentrations that differ by almost an order of magnitude. A two-dimensional solute-transport model, modified to simulate transient groundwater-lake interaction, suggests that the rising water table during the wet season leads to local flow reversals toward the lakes. Response of the individual lakes, however, varies depending on the lake's position in the regional flow system. The most dilute lake is a flow-through lake during the entire year; the through flow is driven by regional groundwater flow. The other permanent lake, which has a higher solute concentration, undergoes seasonal groundwater flow reversals at its downgradient end, resulting in complex seepage patterns and higher solute concentrations in the ground water near the lake. The solute concentration of the intermittent lake is influenced more strongly by the seasonal wetting and drying cycle than by the regional flow system. Although evaporation is the major process affecting the concentration of conservative solutes in the lakes, geochemical and biochemical reactions influence the concentration of nonconservative solutes. Probable reactions in the lakes include biological uptake of solutes and calcite precipitation; probable reactions as lake water seeps into the aquifer are sulfate reduction and calcite dissolution. Seepage reversals can result in water composition that appears inconsistent with predictions based on head measurements because, under transient flow conditions, the flow direction at any instant may not satisfactorily depict the source of the water. Understanding the dynamic nature of groundwater-lake interaction aids in the interpretation of hydrologic and chemical relations between the lakes and the ground water.

Two-photon fluorescence anisotropy imaging

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Yi; Shao, Hanrong; He, Yonghong; Ma, Hui

2006-09-01

We have developed a novel method for imaging the fluorescence intensity and anisotropy by two-photon fluorescence microscopy and tested its capability in biological application. This method is applied to model sample including FITC and FITC-CD44 antibody solution and also FITC-CD44 stained cells. The fluorescence anisotropy (FA) of FITC-CD44ab solution is higher than the FITC solution with the same concentration. The fluorescence in cell sample has even higher FA than in solution because the rotation diffusion is restrained in membrane. The method is employed to study the effect of berberine a kind of Chinese medicine, on tumor metastasis. The results indicated that tumor cell membrane fluidity is decreasing with increasing the concentration of berberine in culture medium.

Concentration dependency in nicotine skin penetration flux from aqueous solutions reflects vehicle induced changes in nicotine stratum corneum retention.

PubMed

Kuswahyuning, Rina; Roberts, Michael S

2014-06-01

This study sought to understand the mechanism by which the steady state flux of nicotine across the human skin from aqueous solutions is markedly decreased at higher nicotine concentrations. Nicotine's steady state flux through human epidermis and its amount in the stratum corneum for a range of aqueous nicotine solutions was determined using Franz diffusion cells, with the nicotine analysed by high performance liquid chromatography (HPLC). Nicotine's thermodynamic activity in the various solutions was estimated from its partial vapour pressure and stratum corneum hydration was determined using a corneometer. The amount of nicotine retained in the stratum corneum was estimated from the nicotine amount found in individual stratum corneum tape strips and a D-Squame determined weight for each strip. The observed steady state flux of nicotine across human epidermis was found to show a parabolic dependence on nicotine concentration, with the flux proportional to its thermodynamic activity up to a concentration of 48% w/w. The nicotine retention in the stratum corneum showed a similar dependency on concentration whereas the diffusivity of nicotine in the stratum corneum appeared to be concentration independent. This retention, in turn, could be estimated from the extent of stratum corneum hydration and the nicotine concentration in the applied solution and volume of water in the skin. Nonlinear dependency of nicotine skin flux on its concentration results from a dehydration induced decrease in its stratum corneum retention at higher concentration and not dehydration induced changes nicotine diffusivity in the stratum corneum.

Contaminant transport in soil with depth-dependent reaction coefficients and time-dependent boundary conditions.

PubMed

Gao, Guangyao; Fu, Bojie; Zhan, Hongbin; Ma, Ying

2013-05-01

Predicting the fate and movement of contaminant in soils and groundwater is essential to assess and reduce the risk of soil contamination and groundwater pollution. Reaction processes of contaminant often decreased monotonously with depth. Time-dependent input sources usually occurred at the inlet of natural or human-made system such as radioactive waste disposal site. This study presented a one-dimensional convection-dispersion equation (CDE) for contaminant transport in soils with depth-dependent reaction coefficients and time-dependent inlet boundary conditions, and derived its analytical solution. The adsorption coefficient and degradation rate were represented as sigmoidal functions of soil depth. Solute breakthrough curves (BTCs) and concentration profiles obtained from CDE with depth-dependent and constant reaction coefficients were compared, and a constant effective reaction coefficient, which was calculated by arithmetically averaging the depth-dependent reaction coefficient, was proposed to reflect the lumped depth-dependent reaction effect. With the effective adsorption coefficient and degradation rate, CDE could produce similar BTCs and concentration profiles as those from CDE with depth-dependent reactions in soils with moderate chemical heterogeneity. In contrast, the predicted concentrations of CDE with fitted reaction coefficients at a certain depth departed significantly from those of CDE with depth-dependent reactions. Parametric analysis was performed to illustrate the effects of sinusoidally and exponentially decaying input functions on solute BTCs. The BTCs and concentration profiles obtained from the solutions for finite and semi-infinite domain were compared to investigate the effects of effluent boundary condition. The finite solution produced higher concentrations at the increasing limb of the BTCs and possessed a higher peak concentration than the semi-infinite solution which had a slightly long tail. Furthermore, the finite solution gave a higher concentration in the immediate vicinity of the exit boundary than the semi-infinite solution. The applicability of the proposed model was tested with a field herbicide and tracer leaching experiment in an agricultural area of northeastern Greece. The simulation results indicated that the proposed CDE with depth-dependent reaction coefficients was able to capture the evolution of metolachlor concentration at the upper soil depths. However, the simulation results at deep depths were not satisfactory as the proposed model did not account for preferential flow observed in the field. Copyright © 2013 Elsevier Ltd. All rights reserved.

Diffusiophoresis of charged colloidal particles in the limit of very high salinity.

PubMed

Prieve, Dennis C; Malone, Stephanie M; Khair, Aditya S; Stout, Robert F; Kanj, Mazen Y

2018-06-13

Diffusiophoresis is the migration of a colloidal particle through a viscous fluid, caused by a gradient in concentration of some molecular solute; a long-range physical interaction between the particle and solute molecules is required. In the case of a charged particle and an ionic solute (e.g., table salt, NaCl), previous studies have predicted and experimentally verified the speed for very low salt concentrations at which the salt solution behaves ideally. The current study presents a study of diffusiophoresis at much higher salt concentrations (approaching the solubility limit). At such large salt concentrations, electrostatic interactions are almost completely screened, thus eliminating the long-range interaction required for diffusiophoresis; moreover, the high volume fraction occupied by ions makes the solution highly nonideal. Diffusiophoretic speeds were found to be measurable, albeit much smaller than for the same gradient at low salt concentrations.

Viscosity Analysis of Dual Variable Domain Immunoglobulin Protein Solutions: Role of Size, Electroviscous Effect and Protein-Protein Interactions.

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2016-01-01

Increased solution viscosity results in difficulties in manufacturing and delivery of therapeutic protein formulations, increasing both the time and production costs, and leading to patient inconvenience. The solution viscosity is affected by the molecular properties of both the solute and the solvent. The purpose of this work was to investigate the effect of size, charge and protein-protein interactions on the viscosity of Dual Variable Domain Immunoglobulin (DVD-Ig(TM)) protein solutions. The effect of size of the protein molecule on solution viscosity was investigated by measuring intrinsic viscosity and excluded volume calculations for monoclonal antibody (mAb) and DVD-Ig(TM) protein solutions. The role of the electrostatic charge resulting in electroviscous effects for DVD-Ig(TM) protein was assessed by measuring zeta potential. Light scattering measurements were performed to detect protein-protein interactions affecting solution viscosity. DVD-Ig(TM) protein exhibited significantly higher viscosity compared to mAb. Intrinsic viscosity and excluded volume calculations indicated that the size of the molecule affects viscosity significantly at higher concentrations, while the effect was minimal at intermediate concentrations. Electroviscous contribution to the viscosity of DVD-Ig(TM) protein varied depending on the presence or absence of ions in the solution. In buffered solutions, negative k D and B 2 values indicated the presence of attractive interactions which resulted in high viscosity for DVD-Ig(TM) protein at certain pH and ionic strength conditions. Results show that more than one factor contributes to the increased viscosity of DVD-Ig(TM) protein and interplay of these factors modulates the overall viscosity behavior of the solution, especially at higher concentrations.

Sugar assimilation and digestive efficiency in Wahlberg's epauletted fruit bat (Epomophorus wahlbergi).

PubMed

Downs, Colleen T; Mqokeli, Babalwa; Singh, Preshnee

2012-03-01

Fruit- and nectar-feeding bats have high energy demands because of the cost of flight, and sugar is a good fuel because it is easily digested and absorbed. This study investigated the digestive efficiency of different sugars at different concentrations in Wahlberg's epauletted fruit bat (Epomophorus wahlbergi). We predicted that the sugar type and concentration would affect the total amount of solution consumed, while the total energy gained and the apparent assimilation efficiency would be high, irrespective of sugar type or concentration. Equicaloric solutions of two sugar types, glucose and sucrose, at low (10%), medium (15%) and high (25%) concentrations were offered in separate trials to bats. Total amount of solution consumed, total energy gained from each solution, and apparent assimilation efficiency, were measured. Bats had higher total volumetric intake of glucose and sucrose at the low concentrations than at the higher concentrations. However, bats maintained similar total energy intake on the respective glucose and sucrose concentrations. Bats were found to have high assimilation efficiencies on both glucose and sucrose irrespective of concentration. As bats used both sugars efficiently to maximize and maintain energy gain, it is expected that they feed opportunistically on fruit in the wild depending on temporal and spatial availability to obtain their energy requirements. Furthermore, fruit with high sucrose or glucose content will be consumed. Copyright © 2011 Elsevier Inc. All rights reserved.

Free Dendritic Growth of Succinonitrile-Acetone Alloys with Thermosolutal Melt Convection

NASA Technical Reports Server (NTRS)

Beckermann, Christoph; Li, Ben Q.

2003-01-01

A stagnant film model of the effects of thermosolutal convection on free dendritic growth of alloys is developed, and its predictions are compared to available earth-based experimental data for succinonitrileacetone alloys. It is found that the convection model gives excellent agreement with the measured dendrite tip velocities and radii for low solute concentrations. However, at higher solute concentrations the present predictions show some deviations from the measured data, and the measured (thermal) Peclet numbers tend to fall even below the predictions from diffusion theory. Furthermore, the measured selection parameter (sigma*) is significantly above the expected value of 0.02 and exhibits strong scatter. It is shown that convection is not responsible for these discrepancies. Some of the deviations between the predicted and measured data at higher supercoolings could be caused by measurement difficulties. The systematic disagreement in the selection parameter for higher solute concentrations and all supercoolings examined, indicates that the theory for the selection of the dendrite tip operating state in alloys may need to be reexamined.

Nattokinase-promoted tissue plasminogen activator release from human cells.

PubMed

Yatagai, Chieko; Maruyama, Masugi; Kawahara, Tomoko; Sumi, Hiroyuki

2008-01-01

When heated to a temperature of 70 degrees C or higher, the strong fibrinolytic activity of nattokinase in a solution was deactivated. Similar results were observed in the case of using Suc-Ala-Ala-Pro-Phe-pNA and H-D-Val-Leu-Lys-pNA, which are synthetic substrates of nattokinase. In the current study, tests were conducted on the indirect fibrinolytic effects of the substances containing nattokinase that had been deactivated through heating at 121 degrees C for 15 min. Bacillus subtilis natto culture solutions made from three types of bacteria strain were heat-treated and deactivated, and it was found that these culture solutions had the ability to generate tissue plasminogen activators (tPA) from vascular endothelial cells and HeLa cells at certain concentration levels. For example, it was found that the addition of heat-treated culture solution of the Naruse strain (undiluted solution) raises the tPA activity of HeLa cells to about 20 times that of the control. Under the same conditions, tPA activity was raised to a level about 5 times higher for human vascular endothelial cells (HUVEC), and to a level about 24 times higher for nattokinase sold on the market. No change in cell count was observed for HeLa cells and HUVEC in the culture solution at these concentrations, and the level of activity was found to vary with concentration. Copyright 2009 S. Karger AG, Basel.

Hydrolysis kinetics of astaxanthin esters and stability of astaxanthin of Haematococcus pluvialis during saponification.

PubMed

Yuan, J P; Chen, F

1999-01-01

The reaction kinetics for the hydrolysis of astaxanthin esters and the degradation of astaxanthin during saponification of the pigment extract from the microalga Haematococcus pluvialis were investigated. Different concentrations of sodium hydroxide in methanol were used for the saponification under nitrogen in darkness at ambient temperature (22 degrees C) followed by the analysis of astaxanthins and other carotenoids using an HPLC method. The concentration of methanolic NaOH solution was important for promoting the hydrolysis of astaxanthin esters and minimizing the degradation of astaxanthin during saponification. With a higher concentration of methanolic NaOH solution, the reaction rate of hydrolysis was high, but the degradation of astaxanthin occurred significantly. The rate constants of the hydrolysis reaction (first order) of astaxanthin esters and the degradation reaction (zero-order) of astaxanthin were directly proportional to the concentration of sodium hydroxide in the saponified solution. Although the concentration of sodium hydroxide in the saponified solution was 0.018 M, complete hydrolysis of astaxanthin esters was achieved in 6 h for different concentrations (10-100 mg/L) of pigment extracts. Results also indicated that a higher temperature should be avoided to minimize the degradation of astaxanthin. In addition, during saponification, no loss of lutein, beta-carotene, and canthaxanthin was found.

Cadmium and zinc in soil solution extracts following the application of phosphate fertilizers.

PubMed

Lambert, Raphaël; Grant, Cynthia; Sauvé, Sébastien

2007-06-01

This study investigated the solubility of cadmium and zinc in soils after the application of phosphate fertilizers containing those two metals. The solubility of cadmium and zinc was assessed by measuring their concentration in soil water extracts. Three monoammonium phosphate fertilizers containing various amounts of metals were applied on cultivated fields for 3 years at three different rates. In order to investigate the effects of long-term applications of fertilizers on the solubility of Cd and Zn, a similar design was used to apply contaminated fertilizers to soils in a laboratory experiment using a single fertilizer addition equivalent to 15 years of application. Phosphate fertilizers increased the concentration of Cd in soil extracts compared to control in 87% and 80% of the treatments in field and laboratory experiments respectively. Both increasing the rate of application and using fertilizer containing more Cd lead to higher Cd concentrations in extracts for the field and the laboratory experiments. The addition of the equivalent of 15 years of fertilizer application in the laboratory results in higher Cd concentration in extracts compared to the field experiment. For Zn, the fertilizer treatments enhanced the metal solution concentration in 83% of field treatments, but no significant correlations could be found between Zn inputs and its concentration in solution. In the laboratory, fertilizer additions increase the Zn concentrations in 53% of the treatments and decrease it in most of the other treatments. The decrease in Zn concentrations in the laboratory trial is attributed to the higher phosphate concentrations in the soil solution; which is presumed to have contributed to the precipitation of Zn-phosphates. For both trials, the metal concentrations in soil extracts cannot be related to the Zn concentration in the fertilizer or the rate of application. The high Zn to Cd ratio is presumably responsible for the Cd increase in the soil extracts due to competitive displacement by Zn. Finally, the observed acidification of soils with fertilizer application will also contribute to metal solubilisation.

Solute boundary layer on a rotating crystal

NASA Astrophysics Data System (ADS)

Povinelli, Michelle L.; Korpela, Seppo A.; Chait, Arnon

1994-11-01

A perturbation analysis has been carried out for the solutal boundary layer next to a rotating crystal. Our aim is to extend the classical results of Burton, Prim and Slicher [1] in order to obtain higher order terms in asymptotic expansions for the concentration field and boundary-layer thickness. Expressions for the effective segregation coefficient are directly obtained from the concentration solution in the two limits that correspond to weak and strong rotation.

Experimental studies of methemoglobinemia due to percutaneous absorption of sodium nitrite.

PubMed

Saito, T; Takeichi, S; Nakajima, Y; Yukawa, N; Osawa, M

1997-01-01

Methemoglobin formation caused by a liniment solution containing sodium nitrite (30 g/L and 140 g/L) was studied in rats with normal or abraded skin, by measuring the methemoglobin concentration before and after application of liniment solutions with differing nitrite concentration. Each liniment solution (120 microL) was applied. Methemoglobin was measured for 180 minutes using a hemoximeter. Simultaneously, arterial blood pressure and cutaneous blood flow was measured by laser Doppler flowmetry and a pressure transducer. After the application of each liniment solution to normal skin, the methemoglobin concentration was not significantly modified depending on the time after application. Application of liniment solution to abraded skin (140 g/L) resulted in a marked increase in methemoglobin concentration. A remarkable decrease in arterial blood pressure and subcutaneous blood flow were observed after application of liniment solution to abraded skin (140 g/L). Each of these findings are characteristic of nitrite and they imply the percutaneous absorption of nitrite. Regardless of the nitrite concentration, the methemoglobin concentration was consistently higher in abraded skin than in normal skin.

Umami compounds enhance the intensity of retronasal sensation of aromas from model chicken soups.

PubMed

Nishimura, Toshihide; Goto, Shingo; Miura, Kyo; Takakura, Yukiko; Egusa, Ai S; Wakabayashi, Hidehiko

2016-04-01

We examined the influence of taste compounds on retronasal aroma sensation using a model chicken soup. The aroma intensity of a reconstituted flavour solution from which glutamic acid (Glu), inosine 5'-monophosphate (IMP), or phosphate was omitted was significantly lower (p<0.05) than that of the model soup. The aroma intensity of 0.4% NaCl solution containing the aroma chicken model (ACM) with added Glu and IMP was significantly higher (p<0.05) than that of 0.4% NaCl solution containing only ACM. The quantitative analyses showed that adding monosodium glutamate (MSG) to aqueous aroma solution containing only ACM enhanced the intensity of retronasal aroma sensation by 2.5-folds with increasing MSG concentration from 0% to 0.3%. Sensation intensity using an umami solution with added MSG and IMP was significantly higher than that with only MSG when the MSG concentration was 0.05%, 0.075%, or 0.1%. However, it plateaued when MSG concentration was beyond 0.3%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protein Conformation and Supercharging with DMSO from Aqueous Solution

NASA Astrophysics Data System (ADS)

Sterling, Harry J.; Prell, James S.; Cassou, Catherine A.; Williams, Evan R.

2011-07-01

The efficacy of dimethyl sulfoxide (DMSO) as a supercharging reagent for protein ions formed by electrospray ionization from aqueous solution and the mechanism for supercharging were investigated. Addition of small amounts of DMSO to aqueous solutions containing hen egg white lysozyme or equine myoglobin results in a lowering of charge, whereas a significant increase in charge occurs at higher concentrations. Results from both near-UV circular dichroism spectroscopy and solution-phase hydrogen/deuterium exchange mass spectrometry indicate that DMSO causes a compaction of the native structure of these proteins at low concentration, but significant unfolding occurs at ~63% and ~43% DMSO for lysozyme and myoglobin, respectively. The DMSO concentrations required to denature these two proteins in bulk solution are ~3-5 times higher than the concentrations required for the onset of supercharging, consistent with a significantly increased concentration of this high boiling point supercharging reagent in the ESI droplet as preferential evaporation of water occurs. DMSO is slightly more basic than m-nitrobenzyl alcohol and sulfolane, two other supercharging reagents, based on calculated proton affinity and gas-phase basicity values both at the B3LYP and MP2 levels of theory, and all three of these supercharging reagents are significantly more basic than water. These results provide additional evidence that the origin of supercharging from aqueous solution is the result of chemical and/or thermal denaturation that occurs in the ESI droplet as the concentration of these supercharging reagents increases, and that proton transfer reactivity does not play a significant role in the charge enhancement observed.

Soil Solution Phosphorus Status and Mycorrhizal Dependency in Leucaena leucocephala†

PubMed Central

Habte, Mitiku; Manjunath, Aswathanarayan

1987-01-01

A phosphorus sorption isotherm was used to establish concentrations of P in a soil solution ranging from 0.002 to 0.807 μg/ml. The influence of P concentration on the symbiotic interaction between the tropical tree legume Leucaena leucocephala and the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum was evaluated in pot experiments. The level of mycorrhizal infection in Leucaena roots increased as the concentration of P was raised from 0.002 to 0.153 μg/ml. Higher levels of P depressed mycorrhizal infection, but the level of infection never declined below 50%. Periodic monitoring of P contents of Leucaena subleaflets indicated that significant mycorrhizal activity was detected as early as 17 days after planting, with the activity peaking 12 to 16 days thereafter. The highest level of mycorrhizal activity was associated with a soil solution P level of 0.021 μg/ml. Even though the mycorrhizal inoculation effect diminished as the concentration of P in the soil solution was increased, mycorrhizal inoculation significantly increased P uptake and dry-matter yield of Leucaena at all levels of soil solution P examined. The concentration of P required by nonmycorrhizal L. leucocephala for maximum yield was 27 to 38 times higher than that required by mycorrhizal L. leucocephala. The results illustrate the very high dependence of L. leucocephala on VAM fungi and the significance of optimizing soil solution phosphorus for enhancing the benefits of the VAM symbiosis. PMID:16347323

The effect of calcium hydroxide, alkali dilution and calcium concentration in mitigating the alkali silica reaction using palm oil fuel ash

NASA Astrophysics Data System (ADS)

Asrah, Hidayati; Mirasa, Abdul Karim; Bolong, Nurmin

2018-02-01

This study investigated the mechanism of how POFA mitigated the ASR expansion. Two types of POFA; the UPOFA and GPOFA with different fineness were used to replace the cement at 20% and 40% and their effects on the mortar bar expansion, calcium hydroxide, alkali dilution, and calcium concentration were investigated. The results showed that UPOFA has a significant ability to mitigate the ASR, even at a lower level of replacement (20%) compared to GPOFA. The mechanism of UPOFA in mitigating the ASR expansion was through a reduction in the calcium hydroxide content, which produced low calcium concentration within the mortar pore solution. Low pore solution alkalinity signified that UPOFA had good alkali dilution effect. Meanwhile, a higher dosage of GPOFA was required to mitigate the ASR expansion. An increase in the pore solution alkalinity of GPOFA mortar indicated higher penetration of alkalis from the NaOH solution, which reduced the alkali dilution effect. However, this was compensated by the increase in the cement dilution effect at higher GPOFA replacement, which controlled the mortar bar expansion below the ASTM limit.

Effects of EDTA and low molecular weight organic acids on soil solution properties of a heavy metal polluted soil.

PubMed

Wu, L H; Luo, Y M; Christie, P; Wong, M H

2003-02-01

A pot experiment was conducted to study the effects of EDTA and low molecular weight organic acids (LMWOA) on the pH, total organic carbon (TOC) and heavy metals in the soil solution in the rhizosphere of Brassica juncea grown in a paddy soil contaminated with Cu, Zn, Pb and Cd. The results show that EDTA and LMWOA have no effect on the soil solution pH. EDTA addition significantly increased the TOC concentrations in the soil solution. The TOC concentrations in treatments with EDTA were significantly higher than those in treatments with LMWOA. Adding 3 mmol kg(-1) EDTA to the soil markedly increased the total concentrations of Cu, Zn, Pb and Cd in the soil solution. Compared to EDTA, LMWOA had a very small effect on the metal concentrations. Total concentrations in the soil solution followed the sequence: EDTA > citric acid (CA) approximately oxalic acid (OA) approximately malic acid (MA) for Cu and Pb; EDTA > MA > CA approximately OA for Zn; and EDTA > MA > CA > OA for Cd. The labile concentrations of Cu, Zn, Pb and Cd showed similar trends to the total concentrations.

Removal of Mercury by Foam Fractionation Using Surfactin, a Biosurfactant

PubMed Central

Chen, Hau-Ren; Chen, Chien-Cheng; Reddy, A. Satyanarayana; Chen, Chien-Yen; Li, Wun Rong; Tseng, Min-Jen; Liu, Hung-Tsan; Pan, Wei; Maity, Jyoti Prakash; Atla, Shashi B.

2011-01-01

The separation of mercury ions from artificially contaminated water by the foam fractionation process using a biosurfactant (surfactin) and chemical surfactants (SDS and Tween-80) was investigated in this study. Parameters such as surfactant and mercury concentration, pH, foam volume, and digestion time were varied and their effects on the efficiency of mercury removal were investigated. The recovery efficiency of mercury ions was highly sensitive to the concentration of the surfactant. The highest mercury ion recovery by surfactin was obtained using a surfactin concentration of 10 × CMC, while recovery using SDS required < 10 × CMC and Tween-80 >10 × CMC. However, the enrichment of mercury ions in the foam was superior with surfactin, the mercury enrichment value corresponding to the highest metal recovery (10.4%) by surfactin being 1.53. Dilute solutions (2-mg L−1 Hg2+) resulted in better separation (36.4%), while concentrated solutions (100 mg L−1) enabled only a 2.3% recovery using surfactin. An increase in the digestion time of the metal solution with surfactin yielded better separation as compared with a freshly-prepared solution, and an increase in the airflow rate increased bubble production, resulting in higher metal recovery but low enrichment. Basic solutions yielded higher mercury separation as compared with acidic solutions due to the precipitation of surfactin under acidic conditions. PMID:22174661

Removal of mercury by foam fractionation using surfactin, a biosurfactant.

PubMed

Chen, Hau-Ren; Chen, Chien-Cheng; Reddy, A Satyanarayana; Chen, Chien-Yen; Li, Wun Rong; Tseng, Min-Jen; Liu, Hung-Tsan; Pan, Wei; Maity, Jyoti Prakash; Atla, Shashi B

2011-01-01

The separation of mercury ions from artificially contaminated water by the foam fractionation process using a biosurfactant (surfactin) and chemical surfactants (SDS and Tween-80) was investigated in this study. Parameters such as surfactant and mercury concentration, pH, foam volume, and digestion time were varied and their effects on the efficiency of mercury removal were investigated. The recovery efficiency of mercury ions was highly sensitive to the concentration of the surfactant. The highest mercury ion recovery by surfactin was obtained using a surfactin concentration of 10 × CMC, while recovery using SDS required < 10 × CMC and Tween-80 >10 × CMC. However, the enrichment of mercury ions in the foam was superior with surfactin, the mercury enrichment value corresponding to the highest metal recovery (10.4%) by surfactin being 1.53. Dilute solutions (2-mg L(-1) Hg(2+)) resulted in better separation (36.4%), while concentrated solutions (100 mg L(-1)) enabled only a 2.3% recovery using surfactin. An increase in the digestion time of the metal solution with surfactin yielded better separation as compared with a freshly-prepared solution, and an increase in the airflow rate increased bubble production, resulting in higher metal recovery but low enrichment. Basic solutions yielded higher mercury separation as compared with acidic solutions due to the precipitation of surfactin under acidic conditions.

Advanced linear Fresnel optics for solar thermal energy (STE) production (Conference Presentation)

NASA Astrophysics Data System (ADS)

Collares-Pereira, Manuel

2016-09-01

One path towards low electricity cost is the use of ever higher concentration values, since that, in turn, will provide less thermal losses at higher temperatures and high temperature operation means higher thermodynamic efficiency in the conversion of heat into electricity. However concentration has an added value, since it is associated with larger primaries (see below) and thus with a reduction of collector rows in any given collector field. That, in turn, will reduce receiver length, connecting pipe lengths, number of components, thermal losses in pipes, heat transfer fluid mass, pumping power required (thus less parasitics), OM necessary, and all of that will contribute towards a lower electricity production cost. Conventional PT and LFR concentrators are, essentially, focusing optics solutions and thus very far from the concentration limits set by Non Imaging Optics. However if a conventional PT optics is designed to accommodate a second stage concentrator (or, even better, if a parabolic like primary is designed in an optimal way with a secondary concentrator for a given receiver) the result will have a much higher concentration, but also, as a consequence, a much larger size, since available evacuated tubular receivers come in basically one (standard) size : 70mm diameter. Thus from a typical aperture size of 6m and a concentration value of 26, to double the concentration value with n.i.o., would bring the aperture close to 12m, a value which is not practical for manufacture, transportation, field installation and operation (think about wind loads, for instance) . But with LFR technology this size limitation is not there at all, and low concentration values can now be substituted by much higher ones, and primaries between 20 and 30 m can be produced for the same tube. Some LFRs on the market do have second stage concentration and offer primaries of about 12m total mirror width when designed for those evacuated tubes. These correspond to a CPC type second stage combined with the conventional primary. But is possible to go much further in concentration ( or better yet, to go much further in CAP value - CAP= C*sinθ) by adopting Advanced LFR configurations which achieve the highest concentration possible for any given θ and do so by simultaneously conserve etendue as much as possible. This talk will present and some of these solutions and discuss their merits for the application in view. It will show that all things considered, Advanced LFR solutions, with Molten Salts operating at 565°C , have a much higher final solar to electricity conversion efficiency than the conventional solutions and thus LFR technology seems to have a future market potential (given its inherently low cost) much beyond its present very low market share.

Delivery of fullerene-containing complexes via microgel swelling and shear-induced release.

PubMed

Tarabukina, Elena; Zoolshoev, Zoolsho; Melenevskaya, Elena; Budtova, Tatiana

2010-01-15

The absorption and release of poly(vinylpyrrolidone)-fullerene C60 complexes (PVP/C60) from a model microgel is studied. A dry microgel based on a chemically cross-linked sodium polyacrylate was swollen in the aqueous solutions of complexes which were afterwards released under shear stress. First, gel swelling degree in static conditions in the excess of PVP/C60 solutions was studied: the degree of swelling decreases with the increase in PVP/C60 concentration. While pure PVP is homogeneously distributed between the gel and the surrounding solution, a slight concentration of complexes outside the gel was recorded. It was attributed to PVP/C60 hydrophobicity leading to the decrease in the thermodynamic quality of fullerene-containing solution being gel solvent. The release of PVP/C60 solutions induced by shear was studied with counter-rotating rheo-optical technique and compared with PVP solution release under the same conditions. The amount of solution released depends on polymer concentration and shear strain. Contrary to pure PVP solutions in which rate of release decreases with the increase in polymer concentration, PVP/C60 complexes are released faster when fullerene concentration inside the gel is higher.

Both solubility and chemical stability of curcumin are enhanced by solid dispersion in cellulose derivative matrices.

PubMed

Li, Bin; Konecke, Stephanie; Wegiel, Lindsay A; Taylor, Lynne S; Edgar, Kevin J

2013-10-15

Amorphous solid dispersions (ASD) of curcumin (Cur) in cellulose derivative matrices, hydroxypropylmethylcellulose acetate succinate (HPMCAS), carboxymethylcellulose acetate butyrate (CMCAB), and cellulose acetate adipate propionate (CAAdP) were prepared in order to investigate the structure-property relationship and identify polymer properties necessary to effectively increase Cur aqueous solution concentration. XRD results indicated that all investigated solid dispersions were amorphous, even at a 9:1 Cur:polymer ratio. Both stability against crystallization and Cur solution concentration from these ASDs were significantly higher than those from physical mixtures and crystalline Cur. Remarkably, curcumin was also stabilized against chemical degradation in solution. Chemical stabilization was polymer-dependent, with stabilization in CAAdP>CMCAB>HPMCAS>PVP, while matrices enhanced solution concentration as PVP>HPMCAS>CMCAB≈CAAdP. HPMCAS/Cur dispersions have useful combinations of pH-triggered release profile, chemical stabilization, and strong enhancement of Cur solution concentration. Copyright © 2013 Elsevier Ltd. All rights reserved.

Variations in peak nasal inspiratory flow among healthy students after using saline solutions.

PubMed

Olbrich Neto, Jaime; Olbrich, Sandra Regina Leite Rosa; Mori, Natália Leite Rosa; Oliveira, Ana Elisa de; Corrente, José Eduardo

2016-01-01

Nasal hygiene with saline solutions has been shown to relieve congestion, reduce the thickening of the mucus and keep nasal cavity clean and moist. Evaluating whether saline solutions improve nasal inspiratory flow among healthy children. Students between 8 and 11 years of age underwent 6 procedures with saline solutions at different concentrations. The peak nasal inspiratory flow was measured before and 30 min after each procedure. Statistical analysis was performed by means of t test, analysis of variance, and Tukey's test, considering p<0.05. We evaluated 124 children at all stages. There were differences on the way a same concentration was used. There was no difference between 0.9% saline solution and 3% saline solution by using a syringe. The 3% saline solution had higher averages of peak nasal inspiratory flow, but it was not significantly higher than the 0.9% saline solution. It is important to offer various options to patients. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Kinetics of insulin aggregation in aqueous solutions upon agitation in the presence of hydrophobic surfaces.

PubMed Central

Sluzky, V; Tamada, J A; Klibanov, A M; Langer, R

1991-01-01

The stability of protein-based pharmaceuticals (e.g., insulin) is important for their production, storage, and delivery. To gain an understanding of insulin's aggregation mechanism in aqueous solutions, the effects of agitation rate, interfacial interactions, and insulin concentration on the overall aggregation rate were examined. Ultraviolet absorption spectroscopy, high-performance liquid chromatography, and quasielastic light scattering analyses were used to monitor the aggregation reaction and identify intermediate species. The reaction proceeded in two stages; insulin stability was enhanced at higher concentration. Mathematical modeling of proposed kinetic schemes was employed to identify possible reaction pathways and to explain greater stability at higher insulin concentration. Images PMID:1946348

Hydration of Kr(aq) in dilute and concentrated solutions

DOE PAGES

Chaudhari, Mangesh I.; Sabo, Dubravko; Pratt, Lawrence R.; ...

2014-10-13

Molecular dynamics simulations of water with both multi-Kr and single Kr atomic solutes are carried out to implement quasi-chemical theory evaluation of the hydration free energy of Kr(aq). This approach obtains free energy differences reflecting Kr–Kr interactions at higher concentrations. Those differences are negative changes in hydration free energies with increasing concentrations at constant pressure. The changes are due to a slight reduction of packing contributions in the higher concentration case. The observed Kr–Kr distributions, analyzed with the extrapolation procedure of Krüger et al., yield a modestly attractive osmotic second virial coefficient, B2 ≈ -60 cm 3/mol. Moreover, the thermodynamicmore » analysis interconnecting these two approaches shows that they are closely consistent with each other, providing support for both approaches.« less

Towards high concentration enhancement of microfluidic temperature gradient focusing of sample solutes using combined AC and DC field induced Joule heating.

PubMed

Ge, Zhengwei; Wang, Wei; Yang, Chun

2011-04-07

It is challenging to continuously concentrate sample solutes in microfluidic channels. We present an improved electrokinetic technique for enhancing microfluidic temperature gradient focusing (TGF) of sample solutes using combined AC and DC field induced Joule heating effects. The introduction of an AC electric field component services dual functions: one is to produce Joule heat for generating temperature gradient; the other is to suppress electroosmotic flow. Consequently the required DC voltages for achieving sample concentration by Joule heating induced TGF are reduced, thereby leading to smaller electroosmotic flow (EOF) and thus backpressure effects. As a demonstration, the proposed technique can lead to concentration enhancement of sample solutes of more than 2500-fold, which is much higher than the existing literature reported microfluidic concentration enhancement by utilizing the Joule heating induced TGF technique.

Xanthan gum recovery from fermentation broth using ultrafiltration: Kinetics and process evaluation

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

Lo, Y.M.; Yang, S.T.; Min, D.B.

1995-12-01

Ultrafiltration of xanthan gum solution as an alternative method to alcohol precipitation for xanthan gum recovery from dilute fermentation broth was studied. A polysulfone membrane (with 500,000 MWCO) hollow fiber (106 mil fiber diameter) tubular cartridge was used to concentrate xanthan broth from less than 3 (w/v) % to {approximately}13.5 (w/v) %, with the xanthan recovery yield of {approximately}95 % or higher. During ultrafiltration, the filtrate flux was one order of magnitude lower for xanthan broth than for water, However, the flux remained almost constant for xanthan concentrations up to {approximately}8%. It was then reduced dramatically as the xanthan concentrationmore » increased beyond 8%. The reduced filtrate flux was caused by the reduced pumping (shear) rate and higher viscosities at higher xanthan concentrations. At constant xanthan concentration, the filtrate flux remained almost unchanged for the entire period studied, suggesting that the process is not subject to membrane fouling. In general, the filtrate flux decreased with increasing the xanthan concentration and increased with increasing the pumping (shear) rate and the trans-membrane pressure difference. Changing the solution pH had a slight effect on the viscosity of xanthan solution, but did not affect the filtration performance. Even under high-shear-rate conditions, ultrafiltration did not give any adverse effects on the rheological properties and molecular weight of the xanthan polymer. Thus, ultra filtration can be used to concentrate xanthan broth from fermentation by a factor of four or higher and to reduce the subsequent alcohol recovery costs by at least 75 %.« less

Effect of Pb content and solution concentration of Pb{sub x}TiO{sub 3} seed layer on (100)-texture and ferroelectric/dielectric behavior of PZT (52/48) thin films

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

Zhong, Jian; Batra, Vaishali; Han, Hui

The effect of Pb content and solution concentration of lead titanate (Pb{sub x}TiO{sub 3}) seed layer on the texture and electric properties of Pb{sub 1.1}(Zr{sub 0.52},Ti{sub 0.48})O{sub 3} (PZT) thin films was investigated. A variety of seed layers (y Pb{sub x}TiO{sub 3}) with varying solution concentration (y = 0.02, 0.05, 0.1, and 0.2 M) and Pb content (x = 1.0, 1.05, 1.1, and 1.2) was deposited on Pt/TiO{sub 2}/SiO{sub 2}/Si substrates using chemical-solution deposition method. PZT films were then deposited on these seed layers using the same process. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy investigations of the seed layers confirm change in crystal structuremore » with variation in the solution properties. XRD studies of PZT films deposited on seed layers demonstrate that the seed layer helps in enhancing (100)-texture and suppressing (111)-texture. It was observed that PZT films prepared on seed layers with lower solution concentrations results in highly (100)-textured films, which further helps to improve the electric properties. The polarization and dielectric constant of the PZT films were seen to increase while the coercive field decreased with increase in (100)-texture. Irrespective of the seed layer solution concentration, higher Pb content in the seed layer deteriorates the PZT film properties. Ninety-five percent to ninety-six percent (100)-texture was obtained from thin PZT films deposited on seed layers of 0.02 M solution concentration with 1.05 and 1.10 Pb contents, which is higher than the values reported for thick PZT films. Optimization of both Pb content and solution concentration of the seed layer is a promising route to achieve highly (100)-textured PZT films with improved electric properties.« less

Simultaneous contrast: evidence from licking microstructure and cross-solution comparisons.

PubMed

Dwyer, Dominic M; Lydall, Emma S; Hayward, Andrew J

2011-04-01

The microstructure of rats' licking responses was analyzed to investigate both "classic" simultaneous contrast (e.g., Flaherty & Largen, 1975) and a novel discrete-trial contrast procedure where access to an 8% test solution of sucrose was preceded by a sample of either 2%, 8%, or 32% sucrose (Experiments 1 and 2, respectively). Consumption of a given concentration of sucrose was higher when consumed alongside a low rather than high concentration comparison solution (positive contrast) and consumption of a given concentration of sucrose was lower when consumed alongside a high rather than a low concentration comparison solution (negative contrast). Furthermore, positive contrast increased the size of lick clusters while negative contrast decreased the size of lick clusters. Lick cluster size has a positive monotonic relationship with the concentration of palatable solutions and so positive and negative contrasts produced changes in lick cluster size that were analogous to raising or lowering the concentration of the test solution respectively. Experiment 3 utilized the discrete-trial procedure and compared contrast between two solutions of the same type (sucrose-sucrose or maltodextrin-maltodextrin) or contrast across solutions (sucrose-maltodextrin or maltodextrin-sucrose). Contrast effects on consumption were present, but reduced in size, in the cross-solution conditions. Moreover, lick cluster sizes were not affected at all by cross-solution contrasts as they were by same-solution contrasts. These results are consistent with the idea that simultaneous contrast effects depend, at least partially, on sensory mechanisms.

Co-existence of monomers and clusters in concentrated protein solutions

NASA Astrophysics Data System (ADS)

Chinchalikar, Akshay J.; Kumar, Sugam; Aswal, V. K.; Callow, P.; Wagh, A. G.

2012-06-01

Small-angle neutron scattering (SANS) measurements have been performed on concentrated protein solutions in order to study aggregation of lysozyme molecules at different pH. The variation of correlation peak in concentration (C) dependent SANS data shows deviation from C1/3 behavior suggesting the aggregation phenomena in these systems. The aggregates or clusters coexist along with monomers with cluster fraction proportional to protein concentration. The clustering is also favored at higher pH approaching isoelectric point (pI) because of decrease in charge on the protein molecule.

Mechanisms to Detoxify Selected Organic Contaminants in Higher Plants and Microbes, and Their Potential Use in Landscape Management

DTIC Science & Technology

2004-10-01

presence of plants. The plants were cultivated in hydroponics . Five-day old seedlings were exposed to 0.1 mM TNT solution and the TNT concentration in the...compound in the soil or nutrient solution . In the second phase, they accumulate slowly in the tissues. The intensity of the absorption process...absorption rate is directly proportional to the concentration of the compound in the soil or nutrient solution . Temperature strongly influences the

Analysis of the effects of stirring condition of separation of thorium in the elution process of monazite partial solution by solvent impregnated resin method

NASA Astrophysics Data System (ADS)

Prassanti, R.; Putra, D. S.; Kusuma, B. P.; Nawawi, F. W.

2018-01-01

Monazite is a natural mineral which contains abundant valuable element such as Radioactive Element and Rare Earth Element(REE). In this experiment, it is proven that solution of residual Thorium Sulfate from Monazite mineral process, can be seperated selectively by using extracting method of Solvent Impregnated Resin(SIR), with the elutant solution HNO3. In the earlier process, Thorium solution is conditioned at PH 1 by using H2SO4. Then REE, Thorium and Uranium elements are seperated. This seperation is conducted by using adsorption method by Amberlite XAD-16 Resin, which has been impregnated by Tributhyl Phosphate extractant. It is continued with elution process, which is aimed to obtain Thorium solution of a higher level of concentration. This elution process is conducted by using HNO3, with the elution variables of the lenght of mixing and amount concentration elutant. Based on this experiment, SIR extracting method is able to dissolve Thorium solution until 63,2%grade and a higher level of %grade about 92,40%. It can be concluded that this SIR method can extracted Thorium elements selectively, improve extracting process recovery, and determine optimum stripping condition in the 45th minutes with elutant concentration of 1,0M HNO3.

Olfactory Impact of Higher Alcohols on Red Wine Fruity Ester Aroma Expression in Model Solution.

PubMed

Cameleyre, Margaux; Lytra, Georgia; Tempere, Sophie; Barbe, Jean-Christophe

2015-11-11

This study focused on the impact of five higher alcohols on the perception of fruity aroma in red wines. Various aromatic reconstitutions were prepared, consisting of 13 ethyl esters and acetates and 5 higher alcohols, all at the average concentrations found in red wine. These aromatic reconstitutions were prepared in several matrices. Sensory analysis revealed the interesting behavior of certain compounds among the five higher alcohols following their individual addition or omission. The "olfactory threshold" of the fruity pool was evaluated in several matrices: dilute alcohol solution, dilute alcohol solution containing 3-methylbutan-1-ol or butan-1-ol individually, and dilute alcohol solution containing the mixture of five higher alcohols, blended together at various concentrations. The presence of 3-methylbutan-1-ol or butan-1-ol alone led to a significant decrease in the "olfactory threshold" of the fruity reconstitution, whereas the mixture of alcohols raised the olfactory threshold. Sensory profiles highlighted changes in the perception of fruity nuances in the presence of the mixture of higher alcohols, with specific perceptive interactions, including a relevant masking effect on fresh- and jammy-fruit notes of the fruity mixture in both dilute alcohol solution and dearomatized red wine matrices. When either 3-methylbutan-1-ol or butan-1-ol was added to the fruity reconstitution in dilute alcohol solution, an enhancement of butyric notes was reported with 3-methylbutan-1-ol and fresh- and jammy-fruit with butan-1-ol. This study, the first to focus on the impact of higher alcohols on fruity aromatic expression, revealed that these compounds participate, both quantitatively and qualitatively, in masking fruity aroma perception in a model fruity wine mixture.

The effect of nitrate on ethylene biofiltration.

PubMed

Lee, Sang-Hun; Li, Congna; Heber, Albert J

2012-11-30

This study investigated the effects of filter media types and nitrate (NO(3)(-)) concentrations in nutrient solutions on C(2)H(4) biofiltration. A new nutrient solution with zero NO(3)(-) concentration was supplied to two perlite-bed biotrickling filters, two perlite-bed biofilters, and two GAC (Granular Activated Carbon)-bed biofilters, while the other with 2 g L(-1) of NO(3)(-) was used for the other two GAC biofilters. All reactors underwent a total test duration of over 175 days with an EBRT (Empty Bed Residence Time) of 30 s, inlet gas flow rate of 7 L min(-1), and inlet C(2)H(4) concentrations of 20-30 mg m(-3). NO(3)(-) concentration and media type significantly affected the C(2)H(4) removal efficiencies in all types of biofiltration. The perlite media with no NO(3)(-) achieved C(2)H(4) removal efficiencies 10-50% higher than the others. A NO(3)(-) concentration as high as 2 g L(-1) in the original nutrient solution may act as an inhibitor that suppresses the growth or activity of C(2)H(4) degraders. In addition, the perlite media resulted in higher C(2)H(4) removal efficiencies than GAC media, because the hydrophilic surface of the perlite leads to a higher moisture content and thus to favorable microbial growth. Copyright © 2012 Elsevier B.V. All rights reserved.

Translational and rotational dynamics of monosaccharide solutions.

PubMed

Lelong, Gérald; Howells, W Spencer; Brady, John W; Talón, César; Price, David L; Saboungi, Marie-Louise

2009-10-01

Molecular dynamics computer simulations have been carried out on aqueous solutions of glucose at concentrations bracketing those previously measured with quasi-elastic neutron scattering (QENS), in order to investigate the motions and interactions of the sugar and water molecules. In addition, QENS measurements have been carried out on fructose solutions to determine whether the effects previously observed for glucose apply to monosaccharide solutions. The simulations indicate a dynamical analogy between higher solute concentration and lower temperature that could provide a key explanation of the bioprotective phenomena observed in many living organisms. The experimental results on fructose solutions show qualitatively similar behavior to the glucose solutions. The dynamics of the water molecules are essentially the same, while the translational diffusion of the sugar molecules is slightly faster in the fructose solutions.

Liquid ``Coffee Rings'' and the Spreading of Volatile Liquid Mixtures

NASA Astrophysics Data System (ADS)

Wood, Clay; Pye, Justin; Burton, Justin

When a volatile liquid drop is placed on a wetting surface, it rapidly spreads and evaporates. The spreading dynamics and drop geometry are determined by a balance between thermal and interfacial forces, including Marangoni effects. However, this spreading behavior is drastically altered when drops contain a miniscule amount of a less-volatile miscible liquid (solute) in the bulk (solvent); contact line instabilities in the form of ``fingers'' develop. Characteristic finger size increases with increasing solute concentration and is apparent for concentrations as small as 0.1% by volume. Also, the spreading rate depends sensitively on the solute concentration, especially if the solute preferentially wets the substrate. At higher solute concentrations, the spreading droplet will form ``beads'' at the contact line, rather than fingers, and are deposited as the solvent recedes and evaporates, leaving behind a complex pattern of solute micro-droplets. Liquid ``coffee rings'' are often left behind after evaporation because there is a high evaporation rate of the solvent at the contact line, which increases the concentration of the solute, and the longevity of the rings depends on the solute vapor pressure. These results highlight the unusual sensitivity to contamination of volatile spreading, and the complex patterns of liquid contamination deposited following evaporation from a wetted surface. NSF 1455086.

[Effects of forest regeneration patterns on the quantity and chemical structure of soil solution dissolved organic matter in a subtropical forest.

PubMed

Yuan, Xiao Chun; Lin, Wei Sheng; Pu, Xiao Ting; Yang, Zhi Rong; Zheng, Wei; Chen, Yue Min; Yang, Yu Sheng

2016-06-01

Using the negative pressure sampling method, the concentrations and spectral characte-ristics of dissolved organic matter (DOM) of soil solution were studied at 0-15, 15-30, 30-60 cm layers in Castanopsis carlesii forest (BF), human-assisted naturally regenerated C. carlesii forest (RF), C. carlesii plantation (CP) in evergreen broad-leaved forests in Sanming City, Fujian Pro-vince. The results showed that the overall trend of dissolved organic carbon (DOC) concentrations in soil solution was RF>CP>BF, and the concentration of dissolved organic nitrogen (DON) was highest in C. carlesii plantation. The concentrations of DOC and DON in surface soil (0-15 cm) were all significantly higher than in the subsurface (30-60 cm). The aromatic index (AI) was in the order of RF>CP>BF, and as a whole, the highest AI was observed in the surface soil. Higher fluorescence intensity and a short wave absorption peak (320 nm) were observed in C. carlesii plantation, suggesting the surface soil of C. carlesii plantation was rich in decomposed substance content, while the degree of humification was lower. A medium wave absorption peak (380 nm) was observed in human-assisted naturally regenerated C. carlesii forest, indicating the degree of humification was higher which would contribute to the storage of soil fertility. In addition, DOM characte-ristics in 30-60 cm soil solution were almost unaffected by forest regeneration patterns.

Cisplatin-Conjugated Porous Gelatin Particles: Assessment of Optimal Conditions for Binding and Release

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

Ohta, Shinichi, E-mail: junryuhei@yahoo.co.jp; Nitta, Norihisa; Sonoda, Akinaga

2010-08-15

This study was designed to evaluate the optimal conditions for binding cisplatin and porous gelatin particles (PGPs) and to establish in vivo drug release pharmacokinetics. PGPs were immersed in cisplatin solutions under different conditions: concentration, immersion time, and temperature. Thereafter, PGPs were washed in distilled water to remove uncombined cisplatin and were then freeze-dried. The platinum concentration (PC) in the PGPs was then measured. For the in vivo release test, 50 mg/kg of the cisplatin-conjugated PGPs was implanted subcutaneously in the abdominal region of two rabbits. PCs in the blood were measured at different time intervals. PCs significantly increased inmore » direct proportion to the concentration and immersion time (p < 0.01). Although PC increased at higher solution temperature, it was not a linear progression. For the in vivo release test, platinum was released from cisplatin-conjugated PGPs after 1 day, and the peak PC was confirmed 2 days after implantation. Platinum in the blood was detected until 7 days after implantation in one rabbit and 15 days after administration in the other rabbit. Platinum binding with PGPs increased with a higher concentration of cisplatin solution at a higher temperature over a longer duration of time. Release of cisplatin from cisplatin-conjugated PGPs was confirmed in vivo.« less

Chemical evaluation of soil-solution in acid forest soils

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.

1996-01-01

Soil-solution chemistry is commonly studied in forests through the use of soil lysimeters.This approach is impractical for regional survey studies, however, because lysimeter installation and operation is expensive and time consuming. To address these problems, a new technique was developed to compare soil-solution chemistry among red spruce stands in New York, Vermont, New Hampshire, Maine. Soil solutions were expelled by positive air pressure from soil that had been placed in a sealed cylinder. Before the air pressure was applied, a solution chemically similar to throughfall was added to the soil to bring it to approximate field capacity. After the solution sample was expelled, the soil was removed from the cylinder and chemically analyzed. The method was tested with homogenized Oa and Bs horizon soils collected from a red spruce stand in the Adirondack Mountains of New York, a red spruce stand in east-central Vermont, and a mixed hardwood stand in the Catskill Mountains of New York. Reproducibility, effects of varying the reaction time between adding throughfall and expelling soil solution (5-65 minutes) and effects of varying the chemical composition of added throughfall, were evaluated. In general, results showed that (i) the method was reproducible (coefficients of variation were generally < 15%), (ii) variations in the length of reaction-time did not affect expelled solution concentrations, and (iii) adding and expelling solution did not cause detectable changes in soil exchange chemistry. Concentrations of expelled solutions varied with the concentrations of added throughfall; the lower the CEC, the more sensitive expelled solution concentrations were to the chemical concentrations of added throughfall. Addition of a tracer (NaBr) showed that the expelled solution was a mixture of added solution and solution that preexisted in the soil. Comparisons of expelled solution concentrations with concentrations of soil solutions collected by zero-tension and tension lysimetry indicated that expelled solution concentrations were higher than those obtained with either type of lysimeter, although there was less difference with tension lysimeters than zero-tension lysimeters. The method used for collection of soil solution should be taken into consideration whenever soil solution data are being interpreted.

Comparison of Corneal Riboflavin Gradients Using Dextran and HPMC Solutions.

PubMed

Ehmke, Tobias; Seiler, Theo G; Fischinger, Isaak; Ripken, Tammo; Heisterkamp, Alexander; Frueh, Beatrice E

2016-12-01

To determine the riboflavin concentration gradient in the anterior corneal stroma when using hydroxypropyl methylcellulose (HPMC) or dextran as the carrier agent. Four different groups of porcine corneas (5 each) were compared regarding the riboflavin concentration in the anterior stroma. Prior to all experiments, stable hydration conditions were established for the corresponding solution. The dextran groups were treated with 0.1% riboflavin in 20% dextran for 10 and 30 minutes and the HPMC groups with 0.1% riboflavin in 1.1% HPMC for 10 and 30 minutes. After imbibition, nonlinear microscopy and consecutive image analysis were used to determine two-photon fluorescence intensities. To determine the riboflavin concentration, corneas were saturated and measured a second time by two-photon microscopy. With this measurement, a proper correction for absorption and scattering could be performed. Ultraviolet-A (UVA) transmission was measured after the application time for each group. Riboflavin concentration decreased with increasing depth and increased with longer application times in all groups. Comparing the dextran for 30 minutes and HPMC for 10 minutes groups, a significantly higher stromal riboflavin concentration was found within the most anterior 70 µm in the dextran group for 30 minutes, whereas deeper than 260 µm HPMC-assisted imbibition for 10 minutes yielded higher concentrations. In dextran-treated corneas, values obtained from pachymetry were substantially reduced, whereas HPMC-assisted imbibition led to a decent swelling. UVA transmission values were higher in dextran-assisted imbibition than in HPMC-assisted imbibition. Stromal riboflavin gradients are similar when applied in dextran for 30 minutes and HPMC for 10 minutes. When using HPMC solutions, a shallower cross-linked volume is expected due to a higher corneal hydration. [J Refract Surg. 2016;32(12):798-802.]. Copyright 2016, SLACK Incorporated.

A combined physicochemical-biological method of NaCl extraction from the irrigation solution in the BTLSS

NASA Astrophysics Data System (ADS)

Trifonov, Sergey V.; Tikhomirov, Alexander A.; Ushakova, Sofya; Tikhomirova, Natalia

2016-07-01

The use of processed human wastes as a source of minerals for plants in closed biotechnical life support systems (BTLSS) leads to high salt levels in the irrigation solution, as urine contains high concentrations of NaCl. It is important to develop a process that would effectively decrease NaCl concentration in the irrigation solution and return this salt to the crew's diet. The salt-tolerant plants (Salicornia europea) used to reduce NaCl concentration in the irrigation solution require higher salt concentrations than those of the solution, and this problem cannot be resolved by concentrating the solution. At the same time, NaCl extracted from mineralized wastes by physicochemical methods is not pure enough to be included in the crew's diet. This study describes an original physicochemical method of NaCl extraction from the solution, which is intended to be used in combination with the biological method of NaCl extraction by using saltwort plants. The physicochemical method produces solutions with high NaCl concentrations, and saltwort plants serve as a biological filter in the final phase, to produce table salt. The study reports the order in which physicochemical and biological methods of NaCl extraction from the irrigation solution should be used to enable rapid and effective inclusion of NaCl into the cycling of the BTLSS with humans. This study was carried out in the IBP SB RAS and supported by the grant of the Russian Science Foundation (Project No. 14-14-00599).

Adhesion, friction, and wear of binary alloys in contact with single-crystal silicon carbide

NASA Technical Reports Server (NTRS)

Miyoshi, K.; Buckley, D. H.

1980-01-01

Sliding friction experiments, conducted with various iron base alloys (alloying elements are Ti, Cr, Mn, Ni, Rh and W) in contact with a single crystal silicon carbide /0001/ surface in vacuum are discussed. Results indicate atomic size misfit and concentration of alloying elements play a dominant role in controlling adhesion, friction, and wear properties of iron-base binary alloys. The controlling mechanism of the alloy properties is as an intrinsic effect involving the resistance to shear fracture of cohesive bonding in the alloy. The coefficient of friction generally increases with an increase in solute concentration. The coefficient of friction increases as the solute-to-iron atomic radius ratio increases or decreases from unity. Alloys having higher solute concentration produce more transfer to silicon carbide than do alloys having low solute concentrations. The chemical activity of the alloying element is also an important parameter in controlling adhesion and friction of alloys.

Prediction the concentration of graphite direct exfoliation by liquid solution with solubility parameters map

NASA Astrophysics Data System (ADS)

Liang, Ko-Yuan; Yang, Wein-Duo

2018-01-01

This study is to discuss solvent selection with graphene dispersion concentration of directly exfoliation graphite. That limiting boundaries of fractional cohesion parameters will be draw on the triangular diagram to prediction and estimate. It is based on the literature of data and check with experimental or other literature results, include organic solution, aqueous solution and ionic liquid. In this work, we found that estimated the graphene dispersion concentration by distance (Ra) of Hansen solubility parameters (HSP) between graphene and solvent, the lower Ra; the higher concentration, some case the lower Ra; the lower dispersion concentration (such as acetone). It is compatible with the graphene dispersion concentration on the Hansen space or Triangular fractional cohesion parameters dispersion diagram. From Triangular fractional cohesion parameters dispersion diagram, 2D maps are more convenient for researchers than 3D maps of Hansen space and quickly to find the appropriate combination of solvents for different application.

Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

PubMed

Chen, Gang; Zhang, Shaohui; Li, Meng; Wei, Yan

2015-01-01

A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

Chemodynamics of heavy metals in long-term contaminated soils: metal speciation in soil solution.

PubMed

Kim, Kwon-Rae; Owens, Gary

2009-01-01

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity (MWHC) after equilibration for 24 h. The free metal concentrations (Cd2+, CU2+, Pb2+, and Zn2+) in soil solution were determined using the Donnan membrane technique (DMT). Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd2+ (3%-52%) and Zn2+ (11%-72%) in soil solutions were generally higher than those of Cu2+ (0.2%-30%) and Pb2+ (0.6%-10%). Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients (K(p)) and dissolved organic carbon did not show any significant influence on K(p).

Effect of a long-term exposure to concentrated sucrose and maltodextrin solutions on the preference, appetence, feed intake and growth performance of post-weaned piglets.

PubMed

Guzmán-Pino, Sergio A; Solà-Oriol, David; Figueroa, Jaime; Dwyer, Dominic M; Pérez, José F

2015-03-15

Commercial pigs display an innate attraction for sweet taste compounds. However, the impact of long-term availability to supplementary carbohydrate solutions on their general feeding behavior has not been examined. In this work we assess the effect of 12-days exposure to 16% sucrose and 16% maltodextrin solutions on the feed intake and growth performance of piglets, and on their preference and appetence for sweet or protein solutions. The innate preference of piglets was assessed by an initial choice test between 2% sucrose and 2% animal plasma solutions for a period of three minutes. Piglets showed higher intake and preference for 2% sucrose than for 2% animal plasma. In Experiment 1, piglets were then free-offered a 16% sucrose solution as a supplement to the diet, showing a higher intake of it than water and a reduction in feed intake and weight gain. A similar situation occurred during the last days of free-exposure to a 16% maltodextrin solution in Experiment 2. The choice test between 2% sucrose and 2% animal plasma solution was repeated after the exposure to the concentrated solutions. In both experiments, a reduction in the initial preference for 2% sucrose was observed. Similarly, piglets that had previous access to the 16% sucrose and 16% maltodextrin solutions showed a decrease in the appetence for 2% sucrose in comparison with that for 2% animal plasma, as measured by a one-pan test at the end of the experiments. It is concluded that long-term exposure to concentrated sucrose and maltodextrin solutions reduces feed intake and growth in weanling piglets, and also reverses their innate preference and appetence for dilute sweet over protein solutions. Copyright © 2015 Elsevier Inc. All rights reserved.

Phospholipid Nonwoven Electrospun Membranes

NASA Astrophysics Data System (ADS)

McKee, Matthew G.; Layman, John M.; Cashion, Matthew P.; Long, Timothy E.

2006-01-01

Nonwoven fibrous membranes were formed from electrospinning lecithin solutions in a single processing step. As the concentration of lecithin increased, the micellar morphology evolved from spherical to cylindrical, and at higher concentrations the cylindrical micelles overlapped and entangled in a fashion similar to polymers in semi-dilute or concentrated solutions. At concentrations above the onset of entanglements of the wormlike micelles, electrospun fibers were fabricated with diameters on the order of 1 to 5 micrometers. The electrospun phospholipid fibers offer the potential for direct fabrication of biologically based, high-surface-area membranes without the use of multiple synthetic steps, complicated electrospinning designs, or postprocessing surface treatments.

Osmotic diuresis-induced hypernatremia: better explained by solute-free water clearance or electrolyte-free water clearance?

PubMed

Popli, Subhash; Tzamaloukas, Antonios H; Ing, Todd S

2014-01-01

Hypernatremia may result from inadequate water intake, excessive water loss or a combination of the two. Osmotic diuresis leads to losses of both solute and water. The relationship between solute and water losses determines the resulting changes in serum osmolality and sodium concentration. Total solute loss is routinely higher than loss of water in osmotic diuresis. Theoretically, then, decreases in serum osmolality (and serum sodium concentration) should follow. In clinical situations of osmotic diuresis, however, reduction in osmolality can take place, but not reduction in serum sodium concentration. It is of note that serum sodium concentration changes are related to urinary losses of sodium and potassium but not to the loss of total solute. In osmotic diuresis, the combined loss of sodium and potassium per liter of urine is lower than the concurrent serum sodium level. Consequently, hypernatremia can ensue. A patient who presented with osmotic diuresis and hypernatremia is described here. In this patient, we have shown that electrolyte-free water clearance is a better index of the effect of osmotic diuresis on serum sodium concentration than the classic solute-free water clearance.

Leachate Properties and Cadmium Migration Through Freeze-thaw Treated Soil Columns.

PubMed

Xu, Meng; Zheng, Yue; Chen, Weiwei; Mao, Na; Guo, Ping

2017-01-01

Soil column leaching experiments were conducted to study the effects of multiple freeze-thaw cycles on the vertical migration of cadmium (Cd). Three Cd-spiked leaching solutions of different properties were derived from snowmelt, sludge, and straw, designated as B, W and J, respectively. The leaching solutions varied in dissolved organic matter (DOM) concentrations in the order of J > W > B. Changes in leachate properties and Cd concentration were observed. The results showed that pH values of all the leachate solutions through freeze-thaw treated soil columns were higher than those of leachates through unfrozen soils. However, electrical conductivity (EC) values decreased compared with leachates in unfrozen treated soil columns. Although the concentrations of DOM in leachate solutions had no evident differences between the freeze-thaw and unfrozen treated soil columns, the concentrations of DOM in the leachate solutions B, W and J were different. Freeze-thaw cycles resulted in increased concentrations of Cd in the leachate solutions in the order J > W > B, and promoted a deeper migration of Cd in the soil columns. Thus, it was shown that freeze-thaw cycles may increase the risk of groundwater pollution by Cd.

Effect of Fe 3+ concentration on MWCNTs formation in liquid arcing method

NASA Astrophysics Data System (ADS)

Shervin, Sh.; Gheytani, S.; Simchi, A.

2010-10-01

The formation of multi-walled carbon nanotubes (MWCNTs) during arc discharge in aqueous solutions of Fe 2(SO 4) 3 and FeCl 3 was studied. The concentration of iron ions changed from zero (deionized water) to 0.25 M and the cathodic products were examined by transmission electron microscopy, Raman spectrometry, and thermal gravimetric analysis. The experimental results showed that the crystallinity of MWCNTs is improved by increasing the concentration of iron ions. Nevertheless, the process yield and overall quality of the produced CNTs were significantly affected by iron concentration in the aqueous solution. This observation suggested that there should be an optimum iron concentration at which the formation of MWCNTs is favored. As compared with the sulfate solution, a higher process yield is obtained in the presence of chloride ions in agreement with previous reports.

Biocompatibility assessment of peritoneal dialysis solutions with a new in vitro model of preconditioned human HL60 cells.

PubMed

Koball, Sebastian; Korten, Gero; Stange, Jan; Schmidt, Reinhard; Mitzner, Steffen

2009-07-01

The purposes of this study were to test the human promyelocytic cell line HL60 for its usability as a new cell model for the immune barrier of the peritoneum, and to investigate the impact of different peritoneal dialysis (PD) solutions in the model. HL60 cells were stimulated by retinoic acid and recombinant human granulocyte and macrophage colony-stimulating factor to differentiate into neutrophilic granulocytes. Cells were incubated in different commercially available PD solutions. After a 4-h incubation, functional (chemiluminescence phagocytosis) and viability tests (Live-Dead, XTT) were performed. High glucose concentrations (>1.36%) and low pH values (<7.0) appeared to be detrimental for neutrophil functions and for neutrophil viability. There is a quantitative correlation between glucose concentration and the cytotoxicity of standard PD solutions (PD 1.36% glucose shows 42.6% higher chemiluminescence than PD 3.86% glucose [P < 0.05]). PD solution containing icodextrin shows 74.3% higher chemiluminescence than PD 3.86% glucose, and PD solution with amino acids shows 52.4% higher chemiluminescence than PD 3.86% glucose which is a sign for better biocompatibility in these tests (P < 0.05). The test system is useful for biocompatibility investigations of PD solutions and their effect on immune cells, for example, neutrophil granulocytes. It does not depend on donor variability and availability in comparison to models based on primary isolated leukocytes.

NMR Water Self–Diffusion and Relaxation Studies on Sodium Polyacrylate Solutions and Gels in Physiologic Ionic Solutions

PubMed Central

Bai, Ruiliang; Basser, Peter J.; Briber, Robert M.; Horkay, Ferenc

2013-01-01

Water self-diffusion coefficients and longitudinal relaxation rates in sodium polyacrylate solutions and gels were measured by NMR, as a function of polymer content and structure in a physiological concentration range of monovalent and divalent cations, Ca2+ and Na+. Several physical models describing the self-diffusion of the solvent were applied and compared. A free-volume model was found to be in good agreement with the experimental results over a wide range of polymer concentrations. The longitudinal relaxation rate exhibited linear dependence on polymer concentration below a critical concentration and showed non-linear behavior at higher concentrations. Both the water self-diffusion and relaxation were less influenced by the polymer in the gel state than in the uncrosslinked polymer solutions. The effect of Na+ on the mobility of water molecules was practically undetectable. By contrast, addition of Ca2+ strongly increased the longitudinal relaxation rate while its effect on the self-diffusion coefficient was much less pronounced. PMID:24409001

NMR Water Self-Diffusion and Relaxation Studies on Sodium Polyacrylate Solutions and Gels in Physiologic Ionic Solutions.

PubMed

Bai, Ruiliang; Basser, Peter J; Briber, Robert M; Horkay, Ferenc

2014-03-15

Water self-diffusion coefficients and longitudinal relaxation rates in sodium polyacrylate solutions and gels were measured by NMR, as a function of polymer content and structure in a physiological concentration range of monovalent and divalent cations, Ca 2+ and Na + . Several physical models describing the self-diffusion of the solvent were applied and compared. A free-volume model was found to be in good agreement with the experimental results over a wide range of polymer concentrations. The longitudinal relaxation rate exhibited linear dependence on polymer concentration below a critical concentration and showed non-linear behavior at higher concentrations. Both the water self-diffusion and relaxation were less influenced by the polymer in the gel state than in the uncrosslinked polymer solutions. The effect of Na + on the mobility of water molecules was practically undetectable. By contrast, addition of Ca 2+ strongly increased the longitudinal relaxation rate while its effect on the self-diffusion coefficient was much less pronounced.

Determination of the solubility of inorganic salts by headspace gas chromatography.

PubMed

Chai, X S; Zhu, J Y

2003-05-09

This work reports a novel method for determination of salt solubility using headspace gas chromatography. A very small amount of volatile compound (such as methanol) is added in the studied solution. Due to the molecular interaction in the solution, the vapor-liquid equilibrium (VLE) partitioning coefficient of the volatile species will change with different salt contents in the solution. Therefore, the concentration of volatile species in the vapor phase is proportional to the salt concentration in the liquid phase, which can be easily determined by headspace gas chromatography. Until the salt concentration in the solution is saturated, the concentration of volatile compound in the vapor phase will continue to increase further and a breakpoint will appear on the VLE curve. The solubility of the salts can be determined by the identification of the breakpoint. It was found that the measured solubility of sodium carbonate and sodium sulfate in aqueous solutions is slightly higher (about 6-7%) than those reported in the literature method. The present method can be easily applied to industrial solution systems.

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

van Gestel, C.A.; Ma, W.C.

The acute toxicity of five chlorophenols for two earthworm species was determined in two sandy soils differing in organic matter content and the results were compared with adsorption data. Adsorption increased with increasing organic matter content of the soils, but for tetra- and pentachlorophenol was also influenced by soil pH. Earthworm toxicity was significantly higher in the soil with a low level of organic matter. This difference disappeared when LC50 values were recalculated to concentrations in soil solution using adsorption data. Eisenia fetida andrei showed LC50 values lower than those of Lumbricus rubellus although bioaccumulation was generally higher in themore » latter species. Toxicity and bioaccumulation based on soil solution concentrations increased with increasing lipophilicity of the chlorophenols. The present results indicate that the toxicity and bioaccumulation and therefore the bioavailability of chlorophenols in soil to earthworms are dependent on the concentration in soil solution and can be predicted on the basis of adsorption data. Both the toxicity of and bioaccumulation data on chlorophenols in earthworms demonstrated surprisingly good agreement with those on chlorophenols in fish.« less

Effects of organic solutes on chemical reactions of aluminum

USGS Publications Warehouse

Lind, Carol J.; Hem, John David

1975-01-01

Concentrations of organic matter in the general range of 1-10 milligrams per litre organic carbon are common in natural water, and many naturally occurrin7 organic compounds form aluminum complexes. The aluminum concentrations in near-neutral pH solutions may be 10-100 times higher than the values predicted from solubility data if formation of such organic complexes is ignored. The processes of polymerization of aluminum hydroxide and precipitation of gibbsite are inhibited by the presence of the organic flavone compound quercetin in concentrations as low as 10 x -5.3 mole per litre. Quercetin forms a complex, with a probable molar ratio of 1:2 aluminum to quercetin, that has a formation constant (f12) of about 10 12. A complex with a higher aluminum-quercetin ratio also was observed, but this material tends to evolve into a compound of low solubility that removes aluminum from solution. In the presence of both dissolved aluminum and aqueous silica, low concentrations of quercetin improved the yield of crystallized kaolinite and halloysite. Small amounts of well-shaped kaolinite and halloysite crystals were identified by electron microscopy in solutions with pH's in the range 6.5-8.5 after 155 days aging in one experimer t and 481 days aging in a repeated experiment. The bulk of the precipitated material was amorphous to X-rays, and crystalline material was too small a proportion of the total to give identifiable X-ray diffraction peaks. The precipitates had aluminum-silicon ratios near 1, and their solubility corresponded to that found by Hem, Roberson, Lind, and Polzer (1973) for similar aluminosilicate precipitated in the absence of organic solutes. The improved yield of crystalline material obtained in the presence of quercetin probably is the result of the influence of the organic compound on the aluminum hydroxide polymerization process. Natural water containing color imparted by organic material tends to be higher in aluminum than would be predicted by pH, silica concentrations, and solubility data for inorganic aluminum species.

Pharmacokinetics of nebulized terbinafine in Hispaniolan Amazon parrots (Amazona ventralis).

PubMed

Emery, Lee C; Cox, Sherry K; Souza, Marcy J

2012-09-01

Aspergillosis is one of the most difficult diseases to treat successfully in avian species. Terbinafine hydrochloride offers numerous potential benefits over traditionally used antifungals for treatment of this disease. Adding nebulized antifungals to treatment strategies is thought to improve clinical outcomes in lung diseases. To determine plasma concentrations of terbinafine after nebulization, 6 adult Hispaniolan Amazon parrots were randomly divided into 2 groups of 3. Each bird was nebulized for 15 minutes with 1 of 2 terbinafine solutions, one made with a crushed tablet and the second with raw drug powder. Blood samples were collected at baseline and at multiple time points up to 720 minutes after completing nebulization. Plasma and nebulization solutions were analyzed by high-performance liquid chromatography. The terbinafine concentration of the solution made with a crushed tablet (0.87 +/- 0.05 mg/mL) was significantly lower than was that made with raw powder (1.02 +/- 0.09 mg/mL). Plasma concentrations of terbinafine did not differ significantly between birds in the 2 groups. Plasma terbinafine concentrations in birds were maintained above in vitro minimum inhibitory concentrations for approximately 1 hour in birds nebulized with the crushed tablet solution and 4 hours in birds nebulized with the raw powder solution. Higher concentrations of solution, longer nebulization periods, or more frequent administration are likely needed to reach therapeutic plasma concentrations of terbinafine for clinically relevant periods in Hispaniolan Amazon parrots.

Cooperative Formation of Icosahedral Proline Clusters from Dimers

NASA Astrophysics Data System (ADS)

Jacobs, Alexander D.; Jovan Jose, K. V.; Horness, Rachel; Raghavachari, Krishnan; Thielges, Megan C.; Clemmer, David E.

2018-01-01

Ion mobility spectrometry-mass spectrometry and Fourier transform infrared spectroscopy (FTIR) techniques were combined with quantum chemical calculations to examine the origin of icosahedral clusters of the amino acid proline. When enantiopure proline solutions are electrosprayed (using nanospray) from 100 mM ammonium acetate, only three peaks are observed in the mass spectrum across a concentration range of five orders of magnitude: a monomer [Pro+H]+ species, favored from 0.001 to 0.01 mM proline concentrations; a dimer [2Pro+H]+ species, the most abundant species for proline concentrations above 0.01 mM; and, the dimer and dodecamer [12Pro+2H]2+ for 1.0 mM and more concentrated proline solutions. Electrospraying racemic D/ L-proline solutions from 100 mM ammonium acetate leads to a monomer at low proline concentrations (0.001 to 0.1 mM), and a dimer at higher concentrations (>0.09 mM), as well as a very small population of 8 to 15 Pro clusters that comprise <0.1% of the total ion signals even at the highest proline concentration. Solution FTIR studies show unique features that increase in intensity in the enantiopure proline solutions, consistent with clustering, presumably from the icosahedral geometry in bulk solution. When normalized for the total proline, these results are indicative of a cooperative formation of the enantiopure 12Pro species from 2Pro. [Figure not available: see fulltext.

Effect of sucrose ester concentration on the interfacial characteristics and physical properties of sodium caseinate-stabilized oil-in-water emulsions.

PubMed

Zhao, Qiangzhong; Liu, Daolin; Long, Zhao; Yang, Bao; Fang, Min; Kuang, Wanmei; Zhao, Mouming

2014-05-15

The effect of sucrose ester (SE) concentration on interfacial tension and surface dilatational modulus of SE and sodium caseinate (NaCas)-SE solutions were investigated. The critical micelle concentration (CMC) of SE was presumed to be 0.05% by measuring interfacial tension of SE solution. The interfacial tension of NaCas-SE solution decreased with increased SE concentration. A sharp increase in surface dilatational modulus of NaCas solution was observed when 0.01% SE was added and a decline was occurred at higher SE level. The influence of SE concentration on droplet size and confocal micrograph, surface protein concentration, ζ-potential and rheological properties of oil-in-water (O/W) emulsions prepared with 1% NaCas was also examined. The results showed that addition of SE reduced droplet size and surface protein concentration of the O/W emulsions. The ζ-potential of the O/W emulsions increased initially and decreased afterward with increased SE concentration. All the O/W emulsions exhibited a shear-thinning behaviour and the data were well-fitted into the Herschel-Bulkley model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Calcium Hypochlorite Solutions: Evaluation of Surface Tension and Effect of Different Storage Conditions and Time Periods over pH and Available Chlorine Content.

PubMed

Leonardo, Natália Gomes e Silva; Carlotto, Israel Bangel; Luisi, Simone Bonato; Kopper, Patrícia Maria Poli; Grecca, Fabiana Soares; Montagner, Francisco

2016-04-01

The aim of this study was to evaluate the pH and the available chlorine content from sodium hypochlorite (NaOCl) and calcium hypochlorite (Ca[OCl]2) solutions stored in different conditions and time periods and the surface tension of Ca(OCl)2 solutions in comparison with NaOCl. Solutions at 0.5%, 1%, 2.5%, and 5.25% concentrations were prepared. The pH level and the available chlorine content of freshly prepared solutions and solutions stored for 30, 60, and 90 days at 25°C, 4°C, or 37°C were evaluated in a digital pH meter and by titration, respectively. Surface tension was tested using a Du Nouy tensiometer (Sigma 702, Force Tensiometer; Attension, Espoo, Finland). Descriptive and inferential statistical analyses were performed. A precipitate formed by 2.5% and 5.25% Ca(OCl)2 solutions was observed. Ca(OCl)2 showed a higher concentration of available chlorine than NaOCl. Both 2.5% and 5.25% NaOCl and Ca(OCl)2 had a decrease in the available chlorine content when compared with freshly prepared solutions; 0.5% and 1% NaOCl tend to have a lower pH compared with 0.5% and 1% Ca(OCl)2. NaOCl, 5.25%, showed higher pH compared with 5.25% Ca(OCl)2. NaOCl and Ca(OCl)2 in 0.5% and 1% concentrations tend to show a reduced pH level, whereas 2.5% and 5.25% solutions showed an increase in pH. The heat contributed to the instability of the solutions. NaOCl showed lower surface tension values than Ca(OCl)2. Ca(OCl)2 solutions are extremely alkaline and tend to have more available chlorine content than NaOCl but have a higher surface tension than NaOCl. Regarding the available chlorine content, these solutions tend to be stable to 30 days of storage when kept at 4°C or at 25°C. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Morphological Diversity in Crystal Growth of l-Ascorbic Acid Dissolved in Methanol

NASA Astrophysics Data System (ADS)

Ito, Miho; Izui, Machiko; Yamazaki, Yoshihiro; Matsushita, Mitsugu

2003-06-01

Morphological diagram with respect to crystal growth of l-ascorbic acid (C6H8O6; so-called vitamin C) from methanol solution on a flat glass dish is presented. Varying humidity and initial concentration of l-ascorbic acid in methanol solution, the following three distinct kinds of growing patterns have been observed: homogeneous disk, concentric ring and dendrite. In addition, in higher concentration clearly faceted small single crystals grow in any humidity less than 90%. Crossovers from one pattern to another were observed, too.

Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

PubMed

Bahrenburg, Sven; Karow, Anne R; Garidel, Patrick

2015-04-01

Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation and solution properties of a galactomannan from Bauhinia monandra seeds.

PubMed

Nwokocha, Louis M; Senan, Chandra; Williams, Peter A; Yadav, Madhav P

2017-08-01

This study reports on the chemical and physicochemical properties of the polysaccharide isolated from Bauhinia monandra seeds. The seeds were found to contain 17.8% polysaccharide which consisted predominantly of galactose and mannose. The Man/Gal ratio was found to be approximately 4:1and the average molar mass was 2.54×10 5 g/mol. The extracted material was also found to contain a small amount of protein (5.35%). The galactomannan produced highly viscous solution; the viscosity-shear rate profile was best described by the Williamson model. The mechanical spectrum of a 0.5wt% solution showed that G″ was greater than G' over the frequency range employed while at higher concentrations G' became greater than G″ above a critical frequency. The solutions obeyed the Cox-Merz rule at low concentrations, but there was some deviation at higher concentrations. Viscosity measurements were undertaken over a range of temperatures and the activation energy of viscous flow was found to be 20.75kJ/mol. The rheological properties of solutions of B. monandra galactomannan indicate that it has comparable characteristics to other commercially important galactomannans such as guar gum and locust bean gum and hence has potential as a thickener in the formulation of food and other related products. Copyright © 2017 Elsevier B.V. All rights reserved.

Nitrogen and potassium concentrations in the nutrients solution for melon plants growing in coconut fiber without drainage.

PubMed

Gratieri, Luiz Augusto; Cecílio Filho, Arthur Bernardes; Barbosa, José Carlos; Pavani, Luiz Carlos

2013-01-01

With the objective of evaluating the effects of N and K concentrations for melon plants, an experiment was carried out from July 1, 2011 to January 3, 2012 in Muzambinho city, Minas Gerais State, Brazil. The "Bonus no. 2" was cultivated at the spacing of 1.1 × 0.4. The experimental design was a randomized complete block with three replications in a 4 × 4 factorial scheme with four N concentrations (8, 12, 16, and 20 mmol L(-1)) and four K concentrations (4, 6, 8, and 10 mmol L(-1)). The experimental plot constituted of eight plants. It was observed that the leaf levels of N and K, of N-NO₃ and of K, and the electrical conductivity (CE) of the substrate increased with the increment of N and K in the nutrients' solution. Substratum pH, in general, was reduced with increments in N concentration and increased with increasing K concentrations in the nutrients' solution. Leaf area increased with increments in N concentration in the nutrients solution. Fertigation with solutions stronger in N (20 mmol L(-1)) and K (10 mmol L(-1)) resulted in higher masses for the first (968 g) and the second (951 g) fruits and crop yield (4,425 gm(-2)).

[Optimization on trehalose loading technique as protective conditioning for lyophilization of human platelets].

PubMed

Liu, Jing-Han; Zhou, Jun; Ouyang, Xi-Lin; Li, Xi-Jin; Lu, Fa-Qiang

2005-08-01

This study was aimed to further optimize trehalose loading technique including loading temperature, loading time, loading solution and loading concentration of trehalose, based on the established parameters. Loading efficiency in plasma was compared with that in buffer at 37 degrees C; the curves of intracellular trehalose concentration versus loading time at 37 degrees C and 16 degrees C were measured; curves of mean platelet volume (MPV) versus loading time and loading concentration were investigated and compared. According to results obtained, the loaing time, loading temperature, loading solution and trehalose concentration were ascertained for high loading efficiency of trehalose into human platelet. The results showed that the loading efficiency in plasma was markedly higher than that in buffer at 37 degrees C, the loading efficiency in plasma at 37 degrees C was significantly higher than that at 16 degrees C and reached 19.51% after loading for 4 hours, but 6.16% at 16 degrees C. MPV at 16 degrees C was increased by 43.2% than that at 37 degrees C, but had no distinct changes with loading time and loading concentration. In loading at 37 degrees C, MPV increased with loading time and loading concentration positively. Loading time and loading concentration displayed synergetic effect on MPV. MPV increased with loading time and concentration while trehalose loading concentration was above 50 mmol/L. It is concluded that the optimization parameters of trehalose loading technique are 37 degrees C (temperature), 4 hours (leading time), plasma (loading solution), 50 mmol/L (feasible trehalose concentration). The trehalose concentration can be adjusted to meet the requirement of lyophilization.

Prevention of thaumasite formation in concrete exposed to sulphate attack

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

Bellmann, F.; Stark, J.

2007-08-15

Thermodynamic calculations were performed to investigate at which sulphate ion concentration hardened concrete can be damaged by the formation of thaumasite. It is indicated that thaumasite can be formed from C-S-H phases and portlandite at very low sulphate concentrations in an aggressive solution. Higher sulphate ion concentrations are required in the absence of portlandite. Still higher sulphate ion concentrations are needed if C-S-H phases with a low calcium/silicon ratio are consumed. Therefore, it is suggested that the formation of thaumasite at low and moderate sulphate concentrations in the attacking solution can be avoided by lowering the calcium/silicon ratio in themore » C-S-H phases. This can be achieved by the addition of pozzolanic and latently hydraulic admixtures. During the reaction of these materials, portlandite is consumed and the calcium/silicon ratio of the C-S-H phases is lowered. The aforementioned concept was confirmed by studies published in the literature and also by experimental investigations reported in this paper.« less

A New Neutral-pH Low-GDP Peritoneal Dialysis Fluid

PubMed Central

Himmele, Rainer; Jensen, Lynn; Fenn, Dominik; Ho, Chih-Hu; Sawin, Dixie-Ann; Diaz-Buxo, Jose A.

2012-01-01

♦ Background: Conventional peritoneal dialysis fluids (PDFs) consist of ready-to-use solutions with an acidic pH. Sterilization of these fluids is known to generate high levels of glucose degradation products (GDPs). Although several neutral-pH, low-GDP PD solutions have been developed, none are commercially available in the United States. We analyzed pH and GDPs in Delflex Neutral pH (Fresenius Medical Care North America, Waltham, MA, USA), the first neutral-pH PDF to be approved by the US Food and Drug Administration. ♦ Methods: We evaluated whether patients (n = 26; age range: 18 - 78 years) could properly mix the Delflex Neutral pH PDF after standardized initial training. We further analyzed the concentrations of 10 different glucose degradation products in Delflex Neutral pH PDF and compared the results with similar analyses in other commercially available biocompatible PDFs. ♦ Results: All pH measurements (n = 288) in the delivered Delflex Neutral pH solution consistently fell within the labeled range of 7.0 ± 0.4. Analysis of mixing errors showed no significant impact on the pH results. Delflex Neutral pH, Balance (Fresenius Medical Care, Bad Homburg, Germany), BicaVera (Fresenius Medical Care), and Gambrosol Trio (Gambro Lundia AB, Lund, Sweden) exhibited similar low total GDP concentrations, with maximums in the 4.25% solutions of 88 μmol/L, 74 μmol/L, 74 μmol/L, and 79 μmol/L respectively; the concentration in Physioneal (Baxter Healthcare Corporation, Deerfield, IL, USA) was considerably higher at 263.26 μmol/L. The total GDP concentration in Extraneal (Baxter Healthcare Corporation) was 63 μmol/L, being thus slightly lower than the concentrations in the 4.25% glucose solutions, but higher than the concentrations in the 1.5% and 2.5% glucose solutions. ♦ Conclusions: The new Delflex Neutral pH PDF consistently delivers neutral pH with minimal GDPs. PMID:22383632

Molecular basis of high viscosity in concentrated antibody solutions: Strategies for high concentration drug product development.

PubMed

Tomar, Dheeraj S; Kumar, Sandeep; Singh, Satish K; Goswami, Sumit; Li, Li

2016-01-01

Effective translation of breakthrough discoveries into innovative products in the clinic requires proactive mitigation or elimination of several drug development challenges. These challenges can vary depending upon the type of drug molecule. In the case of therapeutic antibody candidates, a commonly encountered challenge is high viscosity of the concentrated antibody solutions. Concentration-dependent viscosity behaviors of mAbs and other biologic entities may depend on pairwise and higher-order intermolecular interactions, non-native aggregation, and concentration-dependent fluctuations of various antibody regions. This article reviews our current understanding of molecular origins of viscosity behaviors of antibody solutions. We discuss general strategies and guidelines to select low viscosity candidates or optimize lead candidates for lower viscosity at early drug discovery stages. Moreover, strategies for formulation optimization and excipient design are also presented for candidates already in advanced product development stages. Potential future directions for research in this field are also explored.

Iodine addition using triiodide solutions

NASA Technical Reports Server (NTRS)

Rutz, Jeffrey A.; Muckle, Susan V.; Sauer, Richard L.

1992-01-01

The study develops: a triiodide solution for use in preparing ground service equipment (GSE) water for Shuttle support, an iodine dissolution method that is reliable and requires minimal time and effort to prepare, and an iodine dissolution agent with a minimal concentration of sodium salt. Sodium iodide and hydriodic acid were both found to dissolve iodine to attain the desired GSE iodine concentrations of 7.5 +/- 2.5 mg/L and 25 +/- 5 mg/L. The 1.75:1 and 2:1 sodium iodide solutions produced higher iodine recoveries than the 1.2:1 hydriodic acid solution. A two-hour preparation time is required for the three sodium iodide solutions. The 1.2:1 hydriodic acid solution can be prepared in less than 5 min. Two sodium iodide stock solutions (2.5:1 and 2:1) were found to dissolve iodine without undergoing precipitation.

Testing the application of Teflon/quartz soil solution samplers for DOM sampling in the Critical Zone: Field and laboratory approaches

NASA Astrophysics Data System (ADS)

Dolan, E. M.; Perdrial, J. N.; Vazquez, A.; Hernández, S.; Chorover, J.

2010-12-01

Elizabeth Dolan1,2, Julia Perdrial3, Angélica Vázquez-Ortega3, Selene Hernández-Ruiz3, Jon Chorover3 1Deptartment of Soil, Environmental, and Atmospheric Science, University of Missouri. 2Biosphere 2, University of Arizona. 3Deptartment of Soil, Water, and Environmental Science, University of Arizona. Abstract: The behavior of dissolved organic matter (DOM) in soil is important to many biogeochemical processes. Extraction methods to obtain DOM from the unsaturated zone remain a current focus of research as different methods can influence the type and concentration of DOM obtained. Thus, the present comparison study involves three methods for soil solution sampling to assess their impact on DOM quantity and quality: 1) aqueous soil extracts, 2) solution yielded from laboratory installed suction cup samplers and 3) solutions from field installed suction cup samplers. All samples were analyzed for dissolved organic carbon and total nitrogen concentrations. Moreover, DOM quality was analyzed using fluorescence, UV-Vis and FTIR spectroscopies. Results indicate higher DOC values for laboratory extracted DOM: 20 mg/L for aqueous soil extracts and 31 mg/L for lab installed samplers compared to 12 mg/L for field installed samplers. Large variations in C/N ratios were also observed ranging from 1.5 in laboratory extracted DOM to 11 in field samples. Fluorescence excitation-emission matrices of DOM solutions obtained for the laboratory extraction methods showed higher intensities in regions typical for fulvic and humic acid-like materials relative to those extracted in the field. Similarly, the molar absorptivity calculated from DOC concentration normalization of UV-Vis absorbance of the laboratory-derived solutions was significantly higher as well, indicating greater aromaticity. The observed differences can be attributed to soil disturbance associated with obtaining laboratory derived solution samples. Our results indicate that laboratory extraction methods are not comparable to in-situ field soil solution extraction in terms of DOM.

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.

Direct prediction of the solute softening-to-hardening transition in W–Re alloys using stochastic simulations of screw dislocation motion

NASA Astrophysics Data System (ADS)

Zhao, Yue; Marian, Jaime

2018-06-01

Interactions among dislocations and solute atoms are the basis of several important processes in metal plasticity. In body-centered cubic (bcc) metals and alloys, low-temperature plastic flow is controlled by screw dislocation glide, which is known to take place by the nucleation and sideward relaxation of kink pairs across two consecutive Peierls valleys. In alloys, dislocations and solutes affect each other’s kinetics via long-range stress field coupling and short-range inelastic interactions. It is known that in certain substitutional bcc alloys a transition from solute softening to solute hardening is observed at a critical concentration. In this paper, we develop a kinetic Monte Carlo model of screw dislocation glide and solute diffusion in substitutional W–Re alloys. We find that dislocation kinetics is governed by two competing mechanisms. At low solute concentrations, nucleation is enhanced by the softening of the Peierls stress, which dominates over the elastic repulsion of Re atoms on kinks. This trend is reversed at higher concentrations, resulting in a minimum in the flow stress that is concentration and temperature dependent. This minimum marks the transition from solute softening to hardening, which is found to be in reasonable agreement with experiments.

Numerical modeling of solute transport in a sand tank physical model under varying hydraulic gradient and hydrological stresses

NASA Astrophysics Data System (ADS)

Atlabachew, Abunu; Shu, Longcang; Wu, Peipeng; Zhang, Yongjie; Xu, Yang

2018-03-01

This laboratory study improves the understanding of the impacts of horizontal hydraulic gradient, artificial recharge, and groundwater pumping on solute transport through aquifers. Nine experiments and numerical simulations were carried out using a sand tank. The variable-density groundwater flow and sodium chloride transport were simulated using the three-dimensional numerical model SEAWAT. Numerical modelling results successfully reproduced heads and concentrations observed in the sand tank. A higher horizontal hydraulic gradient enhanced the migration of sodium chloride, particularly in the groundwater flow direction. The application of constant artificial recharge increased the spread of the sodium chloride plume in both the longitudinal and lateral directions. In addition, groundwater pumping accelerated spreading of the sodium chloride plume towards the pumping well. Both higher hydraulic gradient and pumping rate generated oval-shaped plumes in the horizontal plane. However, the artificial recharge process produced stretched plumes. These effects of artificial recharge and groundwater pumping were greater under higher hydraulic gradient. The concentration breakthrough curves indicated that emerging solutions never attained the concentration of the originally injected solution. This is probably because of sorption of sodium chloride onto the silica sand and/or the exchange of sodium chloride between the mobile and immobile liquid domains. The fingering and protruding plume shapes in the numerical models constitute instability zones produced by buoyancy-driven flow. Overall, the results have substantiated the influences of hydraulic gradient, boundary condition, artificial recharge, pumping rate and density differences on solute transport through a homogeneous unconfined aquifer. The implications of these findings are important for managing liquid wastes.

Damage suffered by swamp morning glory (Ipomoea aquatica Forsk) exposed to vanadium (V).

PubMed

Chen, Ting; Li, Ting-Qiang; Yang, Jin-Yan

2016-03-01

To elucidate the physiological and morphological responses generated by vanadium (V) in plants, hydroponic culture experiments were performed with swamp morning glory (Ipomoea aquatica Forsk) exposed to 0 mg L(-1) to 2.50 mg L(-1) pentavalent V [V(V)] in Hoagland nutrient solutions. The concentration of chlorophyll a, chlorophyll b, and carotene peaked at a V(V) concentration of 0.05 mg L(-1) and gradually decreased at higher V(V) concentrations. Similarly, the plant biomass was stimulated at low levels of V(V) and was inhibited when V(V) concentrations exceeded 0.1 mg L(-1). Pentavalent V had negative effects on the uptake of phosphorus (P) by roots, shoots, and leaves. The biological absorption coefficients of V of the roots were higher than those of the aerial parts. Under low concentrations of V(V) exposure, the predominant species of V in the aerial parts was tetravalent V [V(IV)], whereas V(V) became more prevalent when concentrations of V(V) in the solution was higher than 0.50 mg L(-1). In the roots, however, the concentrations of V(V) were always higher than those of the V(IV), except in the control group. Organelles in the V(V)-treated leaves were distorted, and the periplasmic space became wider. These results indicate V(V) has concentration-dependent effects on the physiological properties of swamp morning glory, whereas the plant has the ability to develop self-protective function to adapt to the toxicity of V(V). © 2015 SETAC.

Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO3 solution

NASA Astrophysics Data System (ADS)

Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z.

2015-09-01

Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO3 solution. The concentration of HNO3 solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO3. The concentration of HNO3 solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO3 increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO3 solution is most susceptible to ECM. SnO2 forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO3 solution.

Osmosis-driven viscous fingering of oil-in-water emulsions

NASA Astrophysics Data System (ADS)

Liu, Ying; Rallabandi, Bhargav; Baskaran, Mrudhula; Stone, Howard

2017-11-01

Viscous fingering occurs when a low viscosity fluid invades a more viscous fluid. Fingering of two miscible fluids is more complicated than that of immiscible fluids in that there is no sharp fluid-fluid interface and diffusion occurs between the phases. We experimentally studied the fingering of two miscible fluids: an oil-in-water emulsion and a sodium chloride solution. When the concentration of sodium chloride in the water phase in the emulsion exceeds that in the sodium chloride solution, the consequent osmotic flow automatically facilitates the occurrence of the fingering. On the contrary, when the sodium chloride solution has higher concentration, the spreading of emulsion is more uniform than the case without the concentration difference. We provide a model to rationalize and quantify these observations.

A Laboratory Study on the Phase Transition for Polar Stratospheric Cloud Particles

NASA Technical Reports Server (NTRS)

Teets, Edward H., Jr.

1997-01-01

The nucleation and growth of different phases of simulated polar stratospheric cloud (PSC) particles were investigated in the laboratory. Solutions and mixtures of solutions at concentrations 1 to 5 m (molality) of ammonium sulfate, ammonium bisulfate, sodium chloride, sulfuric acid, and nitric acid were supercooled to prescribed temperatures below their equilibrium melting point. These solutions were contained in small diameter glass tubing of volumes ranging from 2.6 to 0.04 ml. Samples were nucleated by insertion of an ice crystal, or in some cases by a liquid nitrogen cooled wire. Crystallization velocities were determined by timing the crystal growth front passages along the glass tubing. Solution mixtures containing aircraft exhaust (soot) were also examined. Crystallization rates increased as deltaT2, where deltaT is the supercooling for weak solutions (2 m or less). The higher concentrated solutions (greater than 3 m) showed rates significantly less than deltaT2. This reduced rate suggested an onset of a glass phase. Results were applied to the nucleation of highly concentrated solutions at various stages of polar stratospheric cloud development within the polar stratosphere.

Approaches to stream solute load estimation for solutes with varying dynamics from five diverse small watershed

USGS Publications Warehouse

Aulenbach, Brent T.; Burns, Douglas A.; Shanley, James B.; Yanai, Ruth D.; Bae, Kikang; Wild, Adam; Yang, Yang; Yi, Dong

2016-01-01

Estimating streamwater solute loads is a central objective of many water-quality monitoring and research studies, as loads are used to compare with atmospheric inputs, to infer biogeochemical processes, and to assess whether water quality is improving or degrading. In this study, we evaluate loads and associated errors to determine the best load estimation technique among three methods (a period-weighted approach, the regression-model method, and the composite method) based on a solute's concentration dynamics and sampling frequency. We evaluated a broad range of varying concentration dynamics with stream flow and season using four dissolved solutes (sulfate, silica, nitrate, and dissolved organic carbon) at five diverse small watersheds (Sleepers River Research Watershed, VT; Hubbard Brook Experimental Forest, NH; Biscuit Brook Watershed, NY; Panola Mountain Research Watershed, GA; and Río Mameyes Watershed, PR) with fairly high-frequency sampling during a 10- to 11-yr period. Data sets with three different sampling frequencies were derived from the full data set at each site (weekly plus storm/snowmelt events, weekly, and monthly) and errors in loads were assessed for the study period, annually, and monthly. For solutes that had a moderate to strong concentration–discharge relation, the composite method performed best, unless the autocorrelation of the model residuals was <0.2, in which case the regression-model method was most appropriate. For solutes that had a nonexistent or weak concentration–discharge relation (modelR2 < about 0.3), the period-weighted approach was most appropriate. The lowest errors in loads were achieved for solutes with the strongest concentration–discharge relations. Sample and regression model diagnostics could be used to approximate overall accuracies and annual precisions. For the period-weighed approach, errors were lower when the variance in concentrations was lower, the degree of autocorrelation in the concentrations was higher, and sampling frequency was higher. The period-weighted approach was most sensitive to sampling frequency. For the regression-model and composite methods, errors were lower when the variance in model residuals was lower. For the composite method, errors were lower when the autocorrelation in the residuals was higher. Guidelines to determine the best load estimation method based on solute concentration–discharge dynamics and diagnostics are presented, and should be applicable to other studies.

Solubility limits of dibutyl phosphoric acid in uranium-nitric acid solutions

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

Pierce, R.A.

2000-01-04

The Savannah River Site has enriched uranium (EU) solution that has been stored since being purified in its solvent extraction processes. The concentrations in solution are approximately 6 g/L U and 0.1 M nitric acid. Residual tributylphosphate in solution has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 30--50 mg/L. Dibutyl phosphoric acid, in turn, is in equilibrium with (HDBP){sub 2} and DBP{sup {minus}}. Uranium can form compounds with the dibutylphosphate ion (DBP{sup {minus}}) which have limited solubility, thereby creating a nuclear criticality safety issue. Literature reports and earlier SRTC tests have shown that it is feasiblemore » to precipitate U-DBP solid during the storage and processing of EU solutions. As a result, a series of solubility experiments were run at nitric acid concentrations from 0--4.0 M HNO{sub 3}, uranium at 0--90 g/L, and temperatures from 0--30 C. The data shows temperature and nitric acid concentration dependence consistent with what would be expected. With respect to uranium concentration, U-DBP solubility passes through a minimum between 6 and 12 g/L U at the acid concentrations and temperatures studied. However, the minimum shows a slight shift toward lower uranium concentrations at lower nitric acid concentrations. The shifts in solubility are strongly dependent upon the overall ionic strength of the solution. The data also reveal a shift to higher DBP solubility above 0.5 M HNO{sub 3} for both 6 g/L and 12 g/L uranium solutions. Analysis of U-DBP solids from the tests identified distinct differences between precipitates from less than 0.5 M solutions and those from greater than 4 M acid. Analyses identified UO{sub 2}(DBP){sub 2} as the dominant compound present at low acid concentrations in accordance with literature reports. As the acid concentration increases, the crystalline UO{sub 2}(DBP){sub 2} shows molecular substitutions and an increase in amorphous content.« less

Effect of blood flow on near-the-wall mass transport of drugs and other bioactive agents: a simple formula to estimate boundary layer concentrations.

PubMed

Rugonyi, Sandra

2008-04-01

Transport of bioactive agents through the blood is essential for cardiovascular regulatory processes and drug delivery. Bioactive agents and other solutes infused into the blood through the wall of a blood vessel or released into the blood from an area in the vessel wall spread downstream of the infusion/release region and form a thin boundary layer in which solute concentration is higher than in the rest of the blood. Bioactive agents distributed along the vessel wall affect endothelial cells and regulate biological processes, such as thrombus formation, atherogenesis, and vascular remodeling. To calculate the concentration of solutes in the boundary layer, researchers have generally used numerical simulations. However, to investigate the effect of blood flow, infusion rate, and vessel geometry on the concentration of different solutes, many simulations are needed, leading to a time-consuming effort. In this paper, a relatively simple formula to quantify concentrations in a tube downstream of an infusion/release region is presented. Given known blood-flow rates, tube radius, solute diffusivity, and the length of the infusion region, this formula can be used to quickly estimate solute concentrations when infusion rates are known or to estimate infusion rates when solute concentrations at a point downstream of the infusion region are known. The developed formula is based on boundary layer theory and physical principles. The formula is an approximate solution of the advection-diffusion equations in the boundary layer region when solute concentration is small (dilute solution), infusion rate is modeled as a mass flux, and there is no transport of solute through the wall or chemical reactions downstream of the infusion region. Wall concentrations calculated using the formula developed in this paper were compared to the results from finite element models. Agreement between the results was within 10%. The developed formula could be used in experimental procedures to evaluate drug efficacy, in the design of drug-eluting stents, and to calculate rates of release of bioactive substances at active surfaces using downstream concentration measurements. In addition to being simple and fast to use, the formula gives accurate quantifications of concentrations and infusion rates under steady-state and oscillatory flow conditions, and therefore can be used to estimate boundary layer concentrations under physiological conditions.

Solubility and cation exchange in phosphate rock and saturated clinoptilolite mixtures

NASA Technical Reports Server (NTRS)

Allen, E. R.; Hossner, L. R.; Ming, D. W.; Henninger, D. L.

1993-01-01

Mixtures of zeolite and phosphate rock (PR) have the potential to provide slow-release fertilization of plants in synthetic soils by dissolution and ion-exchange reactions. This study was conducted to examine solubility and cation-exchange relationships in mixtures of PR and NH4- and K-saturated clinoptilolite (Cp). Batch-equilibration experiments were designed to investigate the effect of PR source, the proportion of exchangeable K and NH4, and the Cp to PR ratio on solution N, P, K, and Ca concentrations. The dissolution and cation-exchange reactions that occurred after mixing NH4- and K-saturated Cp with PR increased the solubility of the PR and simultaneously released NH4 and K into solution. The more reactive North Carolina (NC) PR rendered higher solution concentrations of NH4 and K when mixed with Cp than did Tennessee (TN) PR. Solution P concentrations for the Cp-NC PR mixture and the Cp-TN PR mixture were similar. Solution concentrations of N, P, K, and Ca and the ratios of these nutrients in solution varied predictably with the type of PR, the Cp/PR ratio, and the proportions of exchangeable K and NH4 on the Cp. Our research indicated that slow-release fertilization using Cp/PR media may provide adequate levels of N, P, and K to support plant growth. Solution Ca concentrations were lower than optimum for plant growth.

Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight

PubMed Central

Zhang, Yanjie; Furyk, Steven; Sagle, Laura B.; Cho, Younhee; Bergbreiter, David E.; Cremer, Paul S.

2008-01-01

The effect of a series of sodium salts on the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide), PNIPAM, was investigated as a function of molecular weight and polymer concentration with a temperature gradient microfluidic device under a dark-field microscope. In solutions containing sufficient concentrations of kosmotropic anions, the phase transition of PNIPAM was resolved into two separate steps for higher molecular weight samples. The first step of this two step transition was found to be sensitive to the polymer’s molecular weight and solution concentration, while the second step was not. Moreover, the binding of chaotropic anions to the polymer was also influenced by molecular weight. Both sets of results could be explained by the formation of intramolecular and intermolecular hydrogen-bonding between polymer chains. By contrast, the hydrophobic hydration of the isopropyl moieties and polymer backbone was found to be unaffected by either the polymer’s molecular weight or solution concentration. PMID:18820735

Elastic constants and pressure derivative of elastic constants of Si1-xGex solid solution

NASA Astrophysics Data System (ADS)

Jivani, A. R.; Baria, J. K.; Vyas, P. S.; Jani, A. R.

2013-02-01

Elastic properties of Si1-xGex solid solution with arbitrary (atomic) concentration (x) are studied using the pseudo-alloy atom model based on the pseudopotential theory and on the higher-order perturbation scheme with the application of our own proposed model potential. We have used local-field correction function proposed by Sarkar et al to study Si-Ge system. The Elastic constants and pressure derivatives of elastic constants of the solid solution is investigated with different concentration x of Ge. It is found in the present study that the calculated numerical values of the aforesaid physical properties of Si-Ge system are function of x. The elastic constants (C11, C12 and C44) decrease linearly with increase in concentration x and pressure derivative of elastic constants (C11, C12 and C44) increase with the concentration x of Ge. This study provides better set of theoretical results for such solid solution for further comparison either with theoretical or experimental results.

Influence of hydroclimatic variations on solute concentration dynamics in nested subtropical catchments with heterogeneous landscapes.

PubMed

Piazza, Gustavo Antonio; Dupas, Rémi; Gascuel-Odoux, Chantal; Grimaldi, Catherine; Pinheiro, Adilson; Kaufmann, Vander

2018-04-20

Despite global efforts to monitor water quality in catchments worldwide, tropical and subtropical zones still lack data to study the influence of human activities and climate variations on solute dynamics. In this study, we monitored ten solutes every two weeks for six years (2010-2015) in three nested catchments (2 to30 km 2 ), which contained heterogeneous landscapes composed of forests and agricultural land, and one small neighboring forested catchment (0.4 km 2 ). Data analysis revealed that i) rainfall, discharge and solute concentrations displayed no clear seasonal patterns, unlike many catchments of the temperate zone; ii) solute concentrations in the agricultural area were higher than those in the forested area, but both areas displayed similar temporal patterns due to a common hydroclimatic driver; iii) all four catchments displayed a chemostatic export regime for most of the solutes, similar to catchments of the temperate zone; and iv) a positive correlation was observed between anion concentrations and ENSO (El Niño-Southern Oscillation) index. ENSO appeared to influence both hydroclimatic and anion dynamics in these subtropical catchments. Copyright © 2018 Elsevier B.V. All rights reserved.

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO2 Gate Insulator TFT with a High Concentration Precursor

PubMed Central

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Zheng, Zeke; Zhou, Shangxiong; Peng, Junbiao; Lu, Xubing

2017-01-01

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO2 films by intentionally increasing the concentration of precursor. The ZrO2 films not only exhibit a low leakage current density of 10−6 A/cm2 at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm2·V−1·s−1 and a Ion/Ioff ratio of 106 in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO2/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness. PMID:28825652

A Simple Method for High-Performance, Solution-Processed, Amorphous ZrO₂ Gate Insulator TFT with a High Concentration Precursor.

PubMed

Cai, Wei; Zhu, Zhennan; Wei, Jinglin; Fang, Zhiqiang; Ning, Honglong; Zheng, Zeke; Zhou, Shangxiong; Yao, Rihui; Peng, Junbiao; Lu, Xubing

2017-08-21

Solution-processed high-k dielectric TFTs attract much attention since they cost relatively little and have a simple fabrication process. However, it is still a challenge to reduce the leakage of the current density of solution-processed dielectric TFTs. Here, a simple solution method is presented towards enhanced performance of ZrO₂ films by intentionally increasing the concentration of precursor. The ZrO₂ films not only exhibit a low leakage current density of 10 -6 A/cm² at 10 V and a breakdown field of 2.5 MV/cm, but also demonstrate a saturation mobility of 12.6 cm²·V -1 ·s -1 and a I on /I off ratio of 10⁶ in DC pulse sputtering IGZO-TFTs based on these films. Moreover, the underlying mechanism of influence of precursor concentration on film formation is presented. Higher concentration precursor results in a thicker film within same coating times with reduced ZrO₂/IGZO interface defects and roughness. It shows the importance of thickness, roughness, and annealing temperature in solution-processed dielectric oxide TFT and provides an approach to precisely control solution-processed oxide films thickness.

Development of apple chips technology

NASA Astrophysics Data System (ADS)

Kowalska, Hanna; Marzec, Agata; Kowalska, Jolanta; Samborska, Kinga; Tywonek, Małgorzata; Lenart, Andrzej

2018-05-01

For develop of apple chips technology without chemical preservation osmotic dehydration in cherry or apple juice concentrates or fructooligosaccharide solutions and convection drying were used. Studies included the effect of dehydration on the mass transfer in apples and the quality of the final product. The temperature, type of osmotic solution and its concentration were changeable. The fruit were tested on mass transfer indicators, stability (water activity), texture (breaking test) and nutritional value (polyphenol content, acidity). Sensory evaluation was also performed. On this basis, the verification of all options was made and the most acceptable samples were selected. Concentration of osmotic solutions at 25°Brix limited solids gain in apples. Under these conditions, the phenomenon of osmosis caused 8-10 times greater water loss than solids gain. Increasing the concentration of solutions up to 50°Brix had a significantly greater impact on mass exchange in apples, compared to increasing the temperature from 40 to 60 °C. Osmotic dehydration before drying did not significantly affect the water activity but increase of the temperature negatively affected on breaking force of the chips. Chips obtained by osmotic dehydration of apples in a cherry concentrate solution contained significantly more polyphenols, and were characterized by a higher acidity than the variants obtained by dehydration in concentrated apple juice. Furthermore, they were marked by red color which has been thought as part of the attractiveness of the product. The least sensory acceptable chips were prepared using osmotic pre-treatment in cherry concentrated juice solution with the addition of fructooligosaccharide.

The effect of the corneal epithelium on the intraocular penetration of fluoroquinolone ophthalmic solution.

PubMed

Fukuda, Masamichi; Inoue, Amane; Sasaki, Kazuyuki; Takahashi, Nobuo

2004-01-01

Pharmacokinetic studies of antibacterial agents for infectious eye diseases have usually been performed on normal rabbit eyes. In this study, the intraocular penetration of fluoroquinolone ophthalmic solutions was determined in normal rabbit eyes and in rabbit eyes that had the corneal epithelium intentionally removed. We determined the intraocular penetration of ofloxacin (OFLX), levofloxacin (LVFX), and norfloxacin (NFLX), fluoroquinolone ophthalmic solutions that are already on the market and undergoing clinical studies, by injecting 50 microl of each solution into the cul-de-sacs of rabbit eyes three times at 15-min intervals. The drug concentration at 10, 30, 60, 120, and 240 min after final instillation was determined by high-performance liquid chromatography. The maximum concentration in the aqueous humor of normal rabbit eyes was 2.09 +/- 1.56 microg/ml (60 min, OFLX), 2.57 +/- 1.00 microg/ml (30 min, LVFX), and 0.42 +/- 0.12 microg/ml (120 min, NFLX). The drug concentration in the aqueous humor of eyes with intentionally removed corneal epithelium was 12.50 +/- 5.62 microg/ml (30 min, OFLX), 9.02 +/- 2.45 microg/ml (60 min, LVFX), and 8.54 +/- 5.17 microg/ml (30 min, NFLX). The drug penetration of the eye drops into eyes with removed corneal epithelium was around 6 times (OFLX), 3.5 times (LVFX), and 20 times (NFLX) higher than the penetration into the eye with normal cornea. Among the pharmacokinetic parameters of the three ophthalmic solutions according to the one-compartment model, the maximum concentration in the aqueous and the area under the concentration-time curve in the aqueous tended to be higher in the eyes with intentionally removed corneal epithelia than in those with normal corneas.

Stability of Bortezomib 2.5 mg/mL in Vials and Syringes Stored at 4°C and Room Temperature (23°C)

PubMed Central

Walker, Scott E; Charbonneau, Lauren F; Law, Shirley

2014-01-01

Background: Solutions of bortezomib 1.0 mg/mL for IV administration are reportedly stable for up to 42 days. Recent publications have reported that the safety profile of bortezomib is better with subcutaneous administration than with IV administration. Objective: To evaluate the stability of higher-concentration bortezomib solutions for subcutaneous administration (i.e., 2.5 mg/mL in 0.9% sodium chloride [normal saline or NS]). Methods: On study day 0, twelve 3.5-mg vials of powdered bortezomib were each reconstituted with 1.4 mL of NS to prepare solutions with concentration 2.5 mg/mL. Half of the solutions were subsequently stored in the original vials and half were transferred to syringes. Three of each type of container were stored in the refrigerator (4°C) and the other 3 of each type were stored at room temperature (23°C). Concentration analysis and physical inspection were completed on study days 0, 1, 2, 8, 12, 14, 19, and 21. The concentration of bortezomib was determined by a validated liquid chromatographic method with ultraviolet detection. The expiry date was determined according to the time to achieve 90% of the initial concentration, based on the fastest degradation rate calculated from the 95% confidence interval of the observed degradation rate. Results: The analytical method separated degradation products from bortezomib such that the concentration was measured specifically and accurately (with absolute deviations from known concentration averaging 2.99%), with intraday and interday reproducibility averaging 1.51% and 2.51%, respectively. During the study period, all solutions were observed to retain at least 95.26% of the initial concentration in both types of containers at both temperatures. Conclusions: Bortezomib (3.5 mg in manufacturer’s vial) reconstituted with 1.4 mL NS is physically and chemically stable for up to 21 days at 4°C or 23°C when stored in either the manufacturer’s original glass vial or a syringe. Subcutaneous injection of bortezomib represents a change in practice, and there is a potential safety concern if a solution of the increased concentration used for subcutaneous administration (2.5 mg/mL) is inadvertently used to prepare a dose intended for IV administration. Therefore, it is recommended that sites switching to subcutaneous administration of bortezomib eliminate 1.0 mg/mL IV solutions altogether or institute substantial barriers to prevent IV administration of the higher concentration of bortezomib. PMID:24799719

Rheological Behavior of Xanthan Gum Solution Related to Shear Thinning Fluid Delivery for Subsurface Remediation

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

Zhong, Lirong; Oostrom, Martinus; Truex, Michael J.

Xanthan gum, a biopolymer, forms shear thinning fluids which can be used as delivery media to improve the distribution of remedial amendments injected into heterogeneous subsurface environments. The rheological behavior of the shear thinning solution needs to be known to develop an appropriate design for field injection. In this study, the rheological properties of xanthan gum solutions were obtained under various chemical and environmental conditions relevant to delivery of remedial amendments to groundwater. Higher xanthan concentration raised the absolute solution viscosity and increased the degree of shear thinning. Addition of remedial amendments (e.g., phosphate, sodium lactate, ethyl lactate) caused themore » dynamic viscosity of xanthan gum to decrease, but the solutions maintained shear-thinning properties. Use of simple salt (e.g. Na+, Ca2+) to increase the solution ionic strength also decreased the dynamic viscosity of xanthan and the degree of shear thinning, although the effect is a function of xanthan gum concentration and diminished as the xanthan gum concentration was increased. At high xanthan concentration, addition of salt to the solution increased dynamic viscosity. In the absence of sediments, xanthan gum solutions maintain their viscosity properties for months. However, xanthan gum solutions were shown to lose dynamic viscosity over a period of days to weeks when contacted with saturated site sediment. Loss of viscosity is attributed to physical and biodegradation processes.« less

Soil-solution chemistry in a low-elevation spruce-fir ecosystem, Howland, Maine

USGS Publications Warehouse

Fernandez, Ivan J.; Lawrence, Gregory B.; Son, Yowhan

1995-01-01

Soil solutions were collected monthly by tension and zero-tension lysimeters in a low-elevation red spruce stand in east-central Maine from May 1987 through December 1992. Soil solutions collected by Oa tension lysimeters had higher concentrations of most constituents than the Oa zero-tension lysimeters. In Oa horizon soil solutions growing season concentrations for SO4, Ca, and Mg averaged 57, 43, and 30 μmol L−1 in tension lysimeters, and 43, 28, and 19 μmol L−1 in zero-tension lysimeters, respectively. Because tension lysimeters remove water held by the soil at tensions up to 10 kPa, solutions are assumed to have more time to react with the soil compared to freely draining solutions collected by zero-tension lysimeters. Solutions collected in the Bs horizon by both types of collectors were similar which was attributed to the frequency of time periods when the water table was above the Bs lysimeters. Concentrations of SO4 and NO3 at this site were lower than concentrations reported for most other eastern U.S. spruce-fir sites, but base cation concentrations fell in the same range. Aluminum concentrations in this study were also lower than reported for other sites in the eastern U.S. and Ca/Al ratios did not suggest inhibition of Ca uptake by roots. Concentrations of SO4, Ca, K, and Cl decreased significantly in both the Oa and Bs horizons over the 56-month sampling period, which could reflect decreasing deposition rates for sulfur and base cations, climatic influences, or natural variation. A longer record of measured fluxes will be needed to adequately define temporal trends in solution chemistry and their causes.

Thermochromic platinum complexes

DOEpatents

Kostic, Nenad M.; Zhou, Xia-Ying

1990-05-29

Thermochromic compounds containing the [Pt(dipic)Cl].sup.- anion. These compounds are yellow and monomeric at high temperatures or in low concentrations and abruptly change to red and polymeric at low temperatures or higher solution concentrations. This unusual property allows them to be used as temperature sensors.

Thermochromic platinum complexes

DOEpatents

Kostic, Nenad M.; Zhou, Xia-Ying

1989-08-15

Thermochromic compounds containing the [Pt(dipic)Cl].sup.- anion. These compounds are yellow and monomeric at high temperatures or in low concentrations and abruptly change to red and polymeric at low temperatures or higher solution concentrations. This unusual property allows them to be used as temperature sensors.

Neutral solute transport across osteochondral interface: A finite element approach.

PubMed

Arbabi, Vahid; Pouran, Behdad; Weinans, Harrie; Zadpoor, Amir A

2016-12-08

Investigation of the solute transfer across articular cartilage and subchondral bone plate could nurture the understanding of the mechanisms of osteoarthritis (OA) progression. In the current study, we approached the transport of neutral solutes in human (slight OA) and equine (healthy) samples using both computed tomography and biphasic-solute finite element modeling. We developed a multi-zone biphasic-solute finite element model (FEM) accounting for the inhomogeneity of articular cartilage (superficial, middle and deep zones) and subchondral bone plate. Fitting the FEM model to the concentration-time curves of the cartilage and the equilibrium concentration of the subchondral plate/calcified cartilage enabled determination of the diffusion coefficients in the superficial, middle and deep zones of cartilage and subchondral plate. We found slightly higher diffusion coefficients for all zones in the human samples as compared to the equine samples. Generally the diffusion coefficient in the superficial zone of human samples was about 3-fold higher than the middle zone, the diffusion coefficient of the middle zone was 1.5-fold higher than that of the deep zone, and the diffusion coefficient of the deep zone was 1.5-fold higher than that of the subchondral plate/calcified cartilage. Those ratios for equine samples were 9, 2 and 1.5, respectively. Regardless of the species considered, there is a gradual decrease of the diffusion coefficient as one approaches the subchondral plate, whereas the rate of decrease is dependent on the type of species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact of managed moorland burning on DOC concentrations in soil solutions and stream waters

NASA Astrophysics Data System (ADS)

Palmer, Sheila; Wearing, Catherine; Johnson, Kerrylyn; Holden, Joseph; Brown, Lee

2013-04-01

In the UK uplands, prescribed burning of moorland vegetation is a common practice to maintain suitable habitats for game birds. Many of these landscapes are in catchments covered by significant deposits of blanket peat (typically one metre or more in depth). There is growing interest in the effect of land management on the stability of these peatland carbon stores, and their contribution to dissolved and particulate organic carbon in surface waters (DOC and POC, respectively) and subsequent effects on stream biogeochemistry and ecology. Yet there are surprisingly few published catchment-scale studies on the effect of moorland burning on DOC and POC. As part of the EMBER project, stream chemistry data were collected approximately monthly in ten upland blanket peat catchments in the UK, five of which acted as controls and were not subject to burning. The other five catchments were subject to a history of prescribed burning, typically in small patches (300-900 m2) in rotations of 8-25 years. Soil solution DOC was also monitored at four depths at two intensively studied sites (one regularly burned and one control). At the two intensive sites, soil solution DOC was considerably higher at the burned site, particularly in surface solutions where concentrations in excess of 100 mg/L were recorded on several occasions (median 37 mg/L over 18 months). The high soil solution DOC concentrations at the burned site occurred in the most recently burned plots (less than 2 years prior to start of sampling) and the lowest DOC concentrations were observed in plots burned 15-25 years previously. On average, median stream DOC and POC concentrations were approximately 43% and 35% higher respectively in burned catchments relative to control catchments. All streams exhibited peak DOC in late summer/early autumn with higher peak DOC concentrations in burned catchments (20-66 mg/L) compared to control catchments (18-54 mg/L). During winter months, DOC concentrations were low in control catchments (typically less than 15 mg/L) but were highly variable in burned catchments (9-40 mg/L), implying some instability of peat carbon stores and/or fluctuation in source. The results offer strong evidence for an impact of burning on the delivery of DOC to streams, possibly through increased surface run-off from bare or partially vegetated patches.

Effect of calcium chloride solution immersion on surface hardness of restorative glass ionomer cements.

PubMed

Shiozawa, Maho; Takahashi, Hidekazu; Iwasaki, Naohiko; Uo, Motohiro

2013-01-01

The objective of this study was to evaluate the effect of the concentration of calcium chloride (CaCl2) solution on the surface hardness of restorative glass ionomer cements (GICs). Two high-viscosity GICs, Fuji IX GP and GlasIonomer FX-II, were immersed in several concentrations of CaCl2 solution for 1 day and 1 week. The immersed specimen surfaces were evaluated using microhardness testing, grazing incidence X-ray diffraction, and energy-dispersive X-ray spectroscopy. Immersion in a higher concentration of CaCl2 solution produced a greater increase in the surface hardness. No crystalline substance was observed on the immersed surface. Calcium ions were selectively absorbed in the matrix of the GIC surface after immersion. They reacted with the non-reacted carboxylic acid groups remaining in the cement matrix. These reactions were considered to cause an increase in the surface hardness of the GICs.

Density of Gadolinium Nitrate Solutions for the High Flux Isotope Reactor

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

Taylor, Paul Allen; Lee, Denise L

2009-05-01

In late 1992, the High Flux Isotope Reactor (HFIR) was planning to switch the solution contained in the poison injection tank from cadmium nitrate to gadolinium nitrate. The poison injection system is an emergency system used to shut down the reactor by adding a neutron poison to the cooling water. This system must be able to supply a minimum of 69 pounds of gadolinium to the reactor coolant system in order to guarantee that the reactor would become subcritical. A graph of the density of gadolinium nitrate solutions over a concentration range of 5 to 30 wt% and a temperaturemore » range of 15 to 40{sup o}C was prepared. Routine density measurements of the solution in the poison injection tank are made by HFIR personnel, and an adaptation of the original graph is used to determine the gadolinium nitrate concentration. In late 2008, HFIR personnel decided that the heat tracing that was present on the piping for the poison injection system could be removed without any danger of freezing the solution; however, the gadolinium nitrate solution might get as cold as 5{sup o}C. This was outside the range of the current density-concentration correlation, so the range needed to be expanded. This report supplies a new density-concentration correlation that covers the extended temperature range. The correlation is given in new units, which greatly simplifies the calculation that is required to determine the pounds of gadolinium in the tank solution. The procedure for calculating the amount of gadolinium in the HFIR poison injection system is as follows: (1) Calculate the usable volume in the system; (2) Measure the density of the solution; (3) Calculate the gadolinium concentration using the following equation: Gd(lb/ft{sup 3}) = measured density (g/mL) x 34.681 - 34.785; (4) Calculate the amount of gadolinium in the system using the following equation: Amount of Gd(lb) = Gd concentration (lb/ft{sup 3}) x usable volume (ft{sup 3}). The equation in step 3 is exact for a temperature of 5{sup o}C, and overestimates the gadolinium concentration at all higher temperatures. This guarantees that the calculation is conservative, in that the actual concentration will be at least as high as that calculated. If an additional safety factor is desired, it is recommended that an administrative control limit be set that is higher than the required minimum amount of gadolinium.« less

Stabilization of a supersaturated solution of mefenamic acid from a solid dispersion with EUDRAGIT(®) EPO.

PubMed

Kojima, Taro; Higashi, Kenjirou; Suzuki, Toyofumi; Tomono, Kazuo; Moribe, Kunikazu; Yamamoto, Keiji

2012-10-01

The stabilization mechanism of a supersaturated solution of mefenamic acid (MFA) from a solid dispersion with EUDRAGIT(®) EPO (EPO) was investigated. The solid dispersions were prepared by cryogenic grinding method. Powder X-ray diffractometry, in vitro dissolution test, in vivo oral absorption study, infrared spectroscopy, and solid- and solution-state NMR spectroscopies were used to characterize the solid dispersions. Dissolution tests in acetate buffer (pH 5.5) revealed that solid dispersion showed > 200-fold higher concentration of MFA. Supersaturated solution was stable over 1 month and exhibited improved oral bioavailability of MFA in rats, with a 7.8-fold higher area under the plasma concentration-versus-time curve. Solid-state (1)H spin-lattice relaxation time (T(1)) measurement showed that MFA was almost monomolecularly dispersed in the EPO polymer matrix. Intermolecular interaction between MFA and EPO was indicated by solid-state infrared and (13)C-T(1) measurements. Solution-state (1)H-NMR measurement demonstrated that MFA existed in monomolecular state in supersaturated solution. (1)H-T(1) and difference nuclear Overhauser effect measurements indicated that cross relaxation occurred between MFA and EPO due to the small distance between them. The formation and high stability of the supersaturated solution were attributable to the specifically formed intermolecular interactions between MFA and EPO.

Investigating the air oxidation of V(II) ions in a vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Ngamsai, Kittima; Arpornwichanop, Amornchai

2015-11-01

The air oxidation of vanadium (V(II)) ions in a negative electrolyte reservoir is a major side reaction in a vanadium redox flow battery (VRB), which leads to electrolyte imbalance and self-discharge of the system during long-term operation. In this study, an 80% charged negative electrolyte solution is employed to investigate the mechanism and influential factors of the reaction in a negative-electrolyte reservoir. The results show that the air oxidation of V(II) ions occurs at the air-electrolyte solution interface area and leads to a concentration gradient of vanadium ions in the electrolyte solution and to the diffusion of V(II) and V(III) ions. The effect of the ratio of the electrolyte volume to the air-electrolyte solution interface area and the concentrations of vanadium and sulfuric acid in an electrolyte solution is investigated. A higher ratio of electrolyte volume to the air-electrolyte solution interface area results in a slower oxidation reaction rate. The high concentrations of vanadium and sulfuric acid solution also retard the air oxidation of V(II) ions. This information can be utilized to design an appropriate electrolyte reservoir for the VRB system and to prepare suitable ingredients for the electrolyte solution.

Opalescence in monoclonal antibody solutions and its correlation with intermolecular interactions in dilute and concentrated solutions.

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2015-04-01

Opalescence indicates physical instability of a formulation because of the presence of aggregates or liquid-liquid phase separation in solution and has been reported for monoclonal antibody (mAb) formulations. Increased solution opalescence can be attributed to attractive protein-protein interactions (PPIs). Techniques including light scattering, AUC, or membrane osmometry are routinely employed to measure PPIs in dilute solutions, whereas opalescence is seen at relatively higher concentrations, where both long- and short-range forces contribute to overall PPIs. The mAb molecule studied here shows a unique property of high opalescence because of liquid-liquid phase separation. In this study, opalescence measurements are correlated to PPIs measured in diluted and concentrated solutions using light scattering (kD ) and high-frequency rheology (G'), respectively. Charges on the molecules were calculated using zeta potential measurements. Results indicate that high opalescence and phase separation are a result of the attractive interactions in solution; however, the presence of attractive interactions do not always imply phase separation. Temperature dependence of opalescence suggests that thermodynamic contribution to opalescence is significant and Tcloud can be utilized as a potential tool to assess attractive interactions in solution. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Short-time dynamics of lysozyme solutions with competing short-range attraction and long-range repulsion: Experiment and theory

NASA Astrophysics Data System (ADS)

Riest, Jonas; Nägele, Gerhard; Liu, Yun; Wagner, Norman J.; Godfrin, P. Douglas

2018-02-01

Recently, atypical static features of microstructural ordering in low-salinity lysozyme protein solutions have been extensively explored experimentally and explained theoretically based on a short-range attractive plus long-range repulsive (SALR) interaction potential. However, the protein dynamics and the relationship to the atypical SALR structure remain to be demonstrated. Here, the applicability of semi-analytic theoretical methods predicting diffusion properties and viscosity in isotropic particle suspensions to low-salinity lysozyme protein solutions is tested. Using the interaction potential parameters previously obtained from static structure factor measurements, our results of Monte Carlo simulations representing seven experimental lysoyzme samples indicate that they exist either in dispersed fluid or random percolated states. The self-consistent Zerah-Hansen scheme is used to describe the static structure factor, S(q), which is the input to our calculation schemes for the short-time hydrodynamic function, H(q), and the zero-frequency viscosity η. The schemes account for hydrodynamic interactions included on an approximate level. Theoretical predictions for H(q) as a function of the wavenumber q quantitatively agree with experimental results at small protein concentrations obtained using neutron spin echo measurements. At higher concentrations, qualitative agreement is preserved although the calculated hydrodynamic functions are overestimated. We attribute the differences for higher concentrations and lower temperatures to translational-rotational diffusion coupling induced by the shape and interaction anisotropy of particles and clusters, patchiness of the lysozyme particle surfaces, and the intra-cluster dynamics, features not included in our simple globular particle model. The theoretical results for the solution viscosity, η, are in qualitative agreement with our experimental data even at higher concentrations. We demonstrate that semi-quantitative predictions of diffusion properties and viscosity of solutions of globular proteins are possible given only the equilibrium structure factor of proteins. Furthermore, we explore the effects of changing the attraction strength on H(q) and η.

Measured density and calculated baricity of custom-compounded drugs for chronic intrathecal infusion.

PubMed

Hejtmanek, Michael R; Harvey, Tracy D; Bernards, Christopher M

2011-01-01

To minimize the frequency that intrathecal pumps require refilling, drugs are custom compounded at very high concentrations. Unfortunately, the baricity of these custom solutions is unknown, which is problematic, given baricity's importance in determining the spread of intrathecally administered drugs. Consequently, we measured the density and calculated the baricity of clinically relevant concentrations of multiple drugs used for intrathecal infusion. Morphine, clonidine, bupivacaine, and baclofen were weighed to within 0.0001 g and diluted in volumetric flasks to produce solutions of known concentrations (morphine 1, 10, 25, and 50 mg/mL; clonidine 0.05, 0.5, 1, and 3 mg/mL; bupivacaine 2.5, 5, 10, and 20 mg/mL; baclofen 1, 1.5, 2, and 4 mg/mL). The densities of the solutions were measured at 37°C using the mechanical oscillation method. A "best-fit" curve was calculated for plots of concentration versus density for each drug. All prepared solutions of clonidine and baclofen were hypobaric. Higher concentrations of morphine and bupivacaine were hyperbaric, whereas lower concentrations were hypobaric. The relationship between concentration and density is linear for morphine (r > 0.99) and bupivacaine (r > 0.99) and logarithmic for baclofen (r = 0.96) and clonidine (r = 0.98). This is the first study to examine the relationship between concentration and density for custom drug concentrations commonly used in implanted intrathecal pumps. We calculated an equation that defines the relationship between concentration and density for each drug. Using these equations, clinicians can calculate the density of any solution made from the drugs studied here.

Decolorization of basic dye solutions by electrocoagulation: an investigation of the effect of operational parameters.

PubMed

Daneshvar, N; Oladegaragoze, A; Djafarzadeh, N

2006-02-28

Electrocoagulation (EC) is one of the most effective techniques to remove color and organic pollutants from wastewater, which reduces the sludge generation. In this paper, electrocoagulation has been used for the removal of color from solutions containing C. I. Basic Red 46 (BR46) and C. I. Basic Blue 3 (BB3). These dyes are used in the wool and blanket factories for fiber dyeing. The effect of operational parameters such as current density, initial pH of the solution, time of electrolysis, initial dye concentration and solution conductivity were studied in an attempt to reach higher removal efficiency. The findings in this study shows that an increase in the current density up to 60-80 A m(-2) enhanced the color removal efficiency, the electrolysis time was 5 min and the range of pH was determined between 5.5 and 8.5 for two mentioned dye solutions. It was found that for, the initial concentration of dye in solutions should not be higher than 80 mg l(-1) in order to achieve a high color removal percentage. The optimum conductivity was found to be 8 mS cm(-1), which was adjusted using proper amount of NaCl with the dye concentration of 50 mg l(-1). Electrical energy consumption in the above conditions for the decolorization of the dye solutions containing BR46 and BB3 were 4.70 kWh(kgdye removed)(-1) and 7.57 kWh(kgdye removed)(-1), respectively. Also, during the EC process under the optimized conditions, the COD decreased by more than 75% and 99% in dye solutions containing BB3 and BR46, respectively.

Comparison of the biological activity of the most common sublingual allergen solutions made by two European manufacturers.

PubMed

Mösges, Ralph; Pasch, Norbert; Schlierenkämper, Ulf; Lehmacher, Walter

2006-01-01

The clinical efficacy of sublingual immunotherapy has been documented in numerous studies and meta-analyses and is argued to be a favored alternative to the subcutaneous route if allergic symptoms are treated with a high-dose therapy. What is still lacking is a 'conversion rate' between the biological activities of different allergen solutions to determine the one with the higher concentration. A randomized, double-blind, parallel-group study was done with three groups sensitized to the allergens birch, grass or house dust mite via skin prick test. Staloral in the concentrations 10, 100 and 300 IR and SLITone in the concentration of 1,000 STU per milliliter were used for a computer-based comparison of the geometric mean wheal sizes of the different solutions. For each patient, individual regression curves led to the calculation of a mean corresponding IR value for the SLITone solution. A total of 47 patients took part in this clinical trial, most of whom were sensitized to more than one allergen. Values for birch (30 patients) showed that 1,000 STU corresponded to 77 IR, for grass (29 patients) 1,000 STU matched 78 IR and for house dust mite (30 patients) 1,000 STU matched 27 IR based on dose-response relationships. The Wilcoxon test showed that for all allergens the allergenic activity of the SLITone solution was significantly higher than the 10 IR solution and significantly lower than the 100- and 300-IR solutions. We established a conversion rate between the two leading sublingual allergen solutions on the European market to compare different units of measurement. Copyright (c) 2006 S. Karger AG, Basel.

Comparison of the quantitative analysis performance between pulsed voltage atom probe and pulsed laser atom probe.

PubMed

Takahashi, J; Kawakami, K; Raabe, D

2017-04-01

The difference in quantitative analysis performance between the voltage-mode and laser-mode of a local electrode atom probe (LEAP3000X HR) was investigated using a Fe-Cu binary model alloy. Solute copper atoms in ferritic iron preferentially field evaporate because of their significantly lower evaporation field than the matrix iron, and thus, the apparent concentration of solute copper tends to be lower than the actual concentration. However, in voltage-mode, the apparent concentration was higher than the actual concentration at 40K or less due to a detection loss of matrix iron, and the concentration decreased with increasing specimen temperature due to the preferential evaporation of solute copper. On the other hand, in laser-mode, the apparent concentration never exceeded the actual concentration, even at lower temperatures (20K), and this mode showed better quantitative performance over a wide range of specimen temperatures. These results indicate that the pulsed laser atom probe prevents both detection loss and preferential evaporation under a wide range of measurement conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Toxic effects of lead and nickel nitrate on rat liver chromatin components.

PubMed

Rabbani-Chadegani Iii, Azra; Fani, Nesa; Abdossamadi, Sayeh; Shahmir, Nosrat

2011-01-01

The biological activity of heavy metals is related to their physicochemical interaction with biological receptors. In the present study, the effect of low concentrations of nickel nitrate and lead nitrate (<0.3 mM) on rat liver soluble chromatin and histone proteins was examined. The results showed that addition of various concentrations of metals to chromatin solution preceded the chromatin into aggregation and precipitation in a dose-dependant manner; however, the extent of absorbance changes at 260 and 400 nm was different between two metals. Gel electrophoresis of histone proteins and DNA of the supernatants obtained from the metal-treated chromatin and the controls revealed higher affinity of lead nitrate to chromatin compared to nickel nitrate. Also, the binding affinity of lead nitrate to histone proteins free in solution was higher than nickel. On the basis of the results, it is concluded that lead reacts with chromatin components even at very low concentrations and induce chromatin aggregation through histone-DNA cross-links. Whereas, nickel nitrate is less effective on chromatin at low concentrations, suggesting higher toxicity of lead nitrate on chromatin compared to nickel. Copyright © 2010 Wiley Periodicals, Inc.

Evaluating the Passivation of Corrosion of API-X100 Steel with Cyclic Voltammetry

NASA Astrophysics Data System (ADS)

Eliyan, Faysal Fayez; Alfantazi, Akram

2017-10-01

In this research, cyclic voltammetry, in oxygen-free low bicarbonate-carbonate solutions, was used to study the corrosion reactions of a high-strength steel, API-X100. With cycles of different scan ranges, the effects of cycling, transpassivation, and cathodic reduction on the electrochemistry of the passive films were analyzed. It was found that carbonate in higher concentrations reduces the anodic activity and the cathodic reactions of the surface. Bicarbonate in small concentrations in solutions that contained low carbonate concentrations catalyzed dissolution and disrupted the formation of the passive films, in reference to the measured anodic currents. From the experiments, there was electrochemical evidence that with more cycles, the passive films were growing thicker, the transpassivation deteriorated the passive films, and during the cathodic reduction, the dissolution was occurring at lower potentials to facilitate later the passivation at higher potentials.

Structure of guar in solutions of H{sub 2}O and D{sub 2}O: An ultra-small-angle light-scattering study

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

Gittings, M.R.; Cipelletti, L.; Trappe, V.

2000-05-11

The authors examine the structure of guar as a function of concentration in both H{sub 2}O and D{sub 2}O using several different scattering techniques. The range of scattering vectors spans 5 decades (143 cm{sup {minus}1} < q < 10.3 x 10{sup 6} cm{sup {minus}1}), providing insight into the supramolecular and local organization of the chains. This allows direct characterization of the large-scale aggregate structure of the guar, which can be on the order of 100 {micro}m. The aggregates are most likely loosely interconnected with single chains and other aggregates, and the structure and organization are critical in determining solution viscoelasticmore » properties. The solubility is poorer in D{sub 2}O as evidenced by larger aggregates, higher scattering intensities, a slightly higher fractal dimension, and a sublinear concentration dependence of the intensity. Aggregates were found in dilute neutral guar solutions as well as in cationic guar solutions (in H{sub 2}O), whether screened or unscreened. The presence of aggregates at all concentrations for neutral and charged guar indicates the difficulty in determining a molecular weight of the guar molecule.« less

Soil solution dynamics of Cu and Zn in a Cu- and Zn-polluted soil as influenced by gamma-irradiation and Cu-Zn interaction.

PubMed

Luo, Y M; Yan, W D; Christie, P

2001-01-01

A pot experiment was conducted to study soil solution dynamics of Cu and Zn in a Cu/Zn-polluted soil as influenced by gamma-irradiation and Cu-Zn interaction. A slightly acid sandy loam was amended with Cu and Zn (as nitrates) either singly or in combination (100 mg Cu and 150 mg Zn kg(-1) soil) and was then gamma-irradiated (10 kGy). Unamended and unirradiated controls were included, and spring barley (Hordeum vulgare L. cv. Forrester) was grown for 50 days. Soil solution samples obtained using soil moisture samplers immediately before transplantation and every ten days thereafter were used directly for determination of Cu, Zn, pH and absorbance at 360 nm (A360). Cu and Zn concentrations in the solution of metal-polluted soil changed with time and were affected by gamma-irradiation and metal interaction. gamma-Irradiation raised soil solution Cu substantially but generally decreased soil solution Zn. These trends were consistent with increased dissolved organic matter (A360) and solution pH after gamma-irradiation. Combined addition of Cu and Zn usually gave higher soil solution concentrations of Cu or Zn compared with single addition of Cu or Zn in gamma-irradiated and non-irradiated soils, indicating an interaction between Cu and Zn. Cu would have been organically complexed and consequently maintained a relatively high concentration in the soil solution under higher pH conditions. Zn tends to occur mainly as free ion forms in the soil solution and is therefore sensitive to changes in pH. The extent to which gamma-irradiation and metal interaction affected solubility and bioavailability of Cu and Zn was a function of time during plant growth. Studies on soil solution metal dynamics provide very useful information for understanding metal mobility and bioavailability.

CroFab reconstitution in various media: an in vitro solubility study.

PubMed

Vohra, Rais; Clark, Rick; Kelner, Michael

2008-11-01

We investigated the solubility of Crotalidae Polyvalent Ovine Immune Fab antivenom (CroFab, Savage Labs and Protherics Inc., Brentwood, TN, USA) in solutions not listed in the Food and Drug Administration (FDA)-approved product package insert. We also assessed whether adsorption to plastic tubing occurs with CroFab preparations. Nine vials of expired CroFab were divided into three groups according to the solution used for reconstitution. Assignment to the solution groups of normal saline, lactated Ringer's solution, or half-normal saline (NS, LR, 1/2NS) was blinded. The antivenom was diluted to a final volume of 75 mL of test solution. Protein concentration was measured after reconstitution, after storage at 4-6 degrees C for 4 h, and after passage through plastic intravenous (IV) tubing. Higher measured protein yields were noted when half-normal saline was used in comparison with normal saline at each step of the study. Lactated Ringer's solution yielded higher protein concentrations than normal saline only at one out of the three measurement steps. There was no adsorption effect when CroFab was infused through plastic IV tubing. These data suggest that CroFab is slightly more soluble in the hypotonic solution we tested, and the amounts of measured antivenom did not diminish after 4 h of refrigeration or passage through plastic tubing. Our study may be of relevance when clinicians or pharmacists mix CroFab into non-standard solutions.

Characterization of Physical Structure from Measurements of Sound Velocity in Aqueous Solutions of Various Saccharides and Alditols.

NASA Astrophysics Data System (ADS)

Smith, David Eugene

Little basic research has been reported on the physical structure of aqueous solutions of saccharides. Sound velocimeters can be used to study physical structure of solutions, non-destructively. The La Place relationship was used to calculate adiabatic compressibility values for solutions from experimentally determined values for sound velocity and density. Using a sound velocimeter, aqueous solutions of twelve alditols and saccharides were studied at various concentrations and temperatures. Data indicated that over most of the temperature range employed (20 to 70 C) adiabatic compressibility of the solutions was the dominant factor in defining sound velocity through and structural rigidity of solution. As concentration of solute increased, more rigid structures were formed in solution, which caused sound velocity values to increase with increasing concentrations of solute; maximum sound velocity values were obtained at progressively lower temperatures. Analysis of data for sound velocity, density and adiabatic compressibility of various solutions provided partial insight into effects of each solute molecule on structure of solutions. A furanose form in a monosaccharide contributed to a more rigid structure than did a pyranose ring when below 30C. At higher temperatures the pyranose ring provided more rigidity than did the furanose ring. Hydroxyl groups in the equatorial position generally contributed more to rigidity of structure than did OH groups in axial positions. Disaccharides contributed differences from the inherent monosaccharides. A (beta) glycosidic linkage provided more structural rigidity of solution than did a linkage. Among the alditols, mannitol and sorbitol contributed very similar characteristics to solutions. Xylitol, in solution provided less rigidity, density and sound velocity than did mannitol-sorbitol in proportion to the lower molecular weight or xylitol. From the data for velocity of sound through single sugar solutions values for solutions of mixtures of these sugars at concentrations to 0.9m could be calculated with accuracy. Each sugar contributed independently to structure of solution and sound velocity values. At solute concentrations greater than 0.9m, there appeared to be some interaction among mixed solute molecules in solution.

Room-temperature NaI/H2O compression icing: solute-solute interactions.

PubMed

Zeng, Qingxin; Yao, Chuang; Wang, Kai; Sun, Chang Q; Zou, Bo

2017-10-11

In situ Raman spectroscopy revealed that transiting the concentrated NaI/H 2 O solutions to an ice VI phase and then into an ice VII phase at 298 K proceeds in a way different from that activated by the solute type. Unlike the solute type that raises both the critical pressures P C1 and P C2 , for the liquid-VI, the VI-VII transition simultaneously occurs in the Hofmeister series order: I > Br > Cl > F ∼ 0; concentration increase raises the P C1 faster than the P C2 that remains almost constant at higher NaI/H 2 O molecular number ratios. Concentration increase moves the P C1 along the liquid-VI phase boundary and it finally merges with P C2 at the triple-phase junction featured at 350 K and 3.05 GPa. The highly-deformed H-O bond is less sensitive to the concentration because of the involvement of anion-anion repulsion that weakens the electric field in the hydration shells. Observations confirm that the salt solvation lengthens the O:H nonbond and softens its phonon but relaxes the H-O bond contrastingly. Compression, however, has the opposite effect from that of salt solvation. Therefore, compression recovers the polarization-deformed O:H-O bond first and then proceeds to the phase transitions. The anion-anion interaction discriminates the effect of NaI/H 2 O concentration from that of the solute type at an identical concentration on the phase transitions.

Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO{sub 3} solution

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

Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura

2015-09-25

Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO{sub 3} solution. The concentration of HNO{sub 3} solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth ismore » faster in higher concentration compared with low concentration of HNO{sub 3}. The concentration of HNO{sub 3} solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO{sub 3} increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO{sub 3} solution is most susceptible to ECM. SnO{sub 2} forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO{sub 3} solution.« less

Molecular basis of high viscosity in concentrated antibody solutions: Strategies for high concentration drug product development

PubMed Central

Tomar, Dheeraj S.; Kumar, Sandeep; Singh, Satish K.; Goswami, Sumit; Li, Li

2016-01-01

ABSTRACT Effective translation of breakthrough discoveries into innovative products in the clinic requires proactive mitigation or elimination of several drug development challenges. These challenges can vary depending upon the type of drug molecule. In the case of therapeutic antibody candidates, a commonly encountered challenge is high viscosity of the concentrated antibody solutions. Concentration-dependent viscosity behaviors of mAbs and other biologic entities may depend on pairwise and higher-order intermolecular interactions, non-native aggregation, and concentration-dependent fluctuations of various antibody regions. This article reviews our current understanding of molecular origins of viscosity behaviors of antibody solutions. We discuss general strategies and guidelines to select low viscosity candidates or optimize lead candidates for lower viscosity at early drug discovery stages. Moreover, strategies for formulation optimization and excipient design are also presented for candidates already in advanced product development stages. Potential future directions for research in this field are also explored. PMID:26736022

Investigation of factors affecting in vitro doxorubicin release from PEGylated liposomal doxorubicin for the development of in vitro release testing conditions.

PubMed

Shibata, Hiroko; Izutsu, Ken-Ichi; Yomota, Chikako; Okuda, Haruhiro; Goda, Yukihiro

2015-01-01

Establishing appropriate drug release testing methods of liposomal products for assuring quality and performance requires the determination of factors affecting in vitro drug release. In this study, we investigated the effects of test conditions (human plasma lot, pH/salt concentration in the test media, dilution factor, temperature, ultrasound irradiation, etc.), and liposomal preparation conditions (pH/concentration of ammonium sulfate solution), on doxorubicin (DXR) release from PEGylated liposomal DXR. Higher temperature and lower pH significantly increased DXR release. The evaluation of DXR solubility indicated that the high DXR release induced by low pH may be attributed to the high solubility of DXR at low pH. Ultrasound irradiation induced rapid DXR release in an amplitude-dependent manner. The salt concentration in the test solution, human plasma lot, and dilution factor had a limited impact on DXR-release. Variations in the ammonium sulfate concentration used in solutions for the formation/hydration of liposomes significantly affected DXR release behavior, whereas differences in pH did not. In addition, heating condition in phosphate-buffered saline at lower pH (<6.5) exhibited higher discriminative ability for the release profiles from various liposomes with different concentrations of ammonium sulfate than did ultrasound irradiation. These results are expected to be helpful in the process of establishing appropriate drug release testing methods for PEGylated liposomal DXR.

Conductivity and spectroscopic investigation of bis(trifluoromethanesulfonyl)imide solution in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide.

PubMed

Yu, Lei; Pizio, Benjamin S; Vaden, Timothy D

2012-06-07

Protic ionic liquids (PILs) are promising alternatives to water for swelling Nafion as a fuel cell proton exchange membrane (PEM). PILs can significantly improve the high-temperature performance of a PEM. The proton dissociation and solvation mechanisms in a PIL, which are keys to understanding the proton transportation and conductivity, have not been fully explored. In this paper, we used FTIR, Raman, and electronic spectroscopy with computational simulation techniques to explore the spectroscopic properties of bis(trifluoromethanesulfonyl)imide (HTFSI) solutions in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMITFSI) ionic liquid at concentrations from ∼0.1 to as high as ∼1.0 M. Solution conductivities were measured at room temperature and elevated temperatures up to ∼65 °C. The solution structure and properties depend on the concentration of HTFSI. At lower concentration, around 0.1 M, the HTFSI solution has higher conductivity than pure BMITFSI. However, the conductivity decreases when the concentration increases from 0.1 to 1.0 M. Temperature-dependent conductivities followed the Vogel-Fulcher-Tamman equation at all concentrations. Conductivity and spectroscopy results elucidate the complicated ionization and solvation mechanism of HTFSI in BMITFSI solutions. Raman spectroscopy and density functional theory (DFT) calculations are consistent with the complete ionization of HTFSI to generate solvated H(+) at low concentrations. FTIR, Raman, and electronic spectroscopic results as well as DFT computational simulation indicated that when the concentration is as high as 1.0 M, a significant amount of TFSI(-) is protonated, most likely at the imide nitrogen.

Effects of Zn²⁺ and Cu²⁺ on loach ovaries and ova development.

PubMed

Tang, Jian-Xun; Li, Jun-Rong; Liu, Zhong-Liang; Zhao, Hua; Tao, Xiao-Min; Cheng, Zhang-Shun

2013-10-01

This study compared the accumulation of Zn²⁺ and Cu²⁺ in the ovaries and ova of loaches under different concentrations of Zn²⁺ (1.00, 2.50 and 5.00 mg/L respectively) and Cu²⁺ (0.10, 0.25 and 0.50 mg/L respectively). The results showed that both Zn²⁺ and Cu²⁺ accumulated in the ovaries, and that the relationship between accumulation and time was linear over 20 days of exposure. The accumulation of the metals in ovaries was closely related to the concentration of exposure in the solutions (P<0.05), and was obviously affected by the time and doses. However, the Cu²⁺ concentration was significantly higher than Zn²⁺ (P<0.05). The development level of ova in the ovaries also correlated with the concentration and exposure period in the Zn²⁺ and Cu²⁺ solutions. This study compared the accumulation of Zn 2+ and Cu 2+ in the ovaries and ova of loaches under different concentrations of Zn 2+ (1.00, 2.50 and 5.00 mg/L respectively) and Cu 2+ (0.10, 0.25 and 0.50 mg/L respectively). The results showed that both Zn 2+ and Cu 2+ accumulated in the ovaries, and that the relationship between accumulation and time was linear over 20 days of exposure. The accumulation of the metals in ovaries was closely related to the concentration of exposure in the solutions ( P< 0.05), and was obviously affected by the time and doses. However, the Cu 2+ concentration was significantly higher than Zn 2+ ( P< 0.05). The development level of ova in the ovaries also correlated with the concentration and exposure period in the Zn 2+ and Cu 2+ solutions.

Strengthening of Fe3Al Aluminides by One or Two Solute Elements

NASA Astrophysics Data System (ADS)

Kratochvíl, Petr; Daniš, Stanislav; Minárik, Peter; Pešička, Josef; Král, Robert

2017-09-01

The compressive yield stress of Fe-26Al with additives Ti (0.5 to 4 at. pct), Cr (0.5 to 8 at. pct), Mo (0.5 to 4 at. pct), and V (0.5 to 8 at. pct) at 1073 K (800 °C) has been determined. The effect of the concentration of diverse solutes on the yield stress at 1073 K (800 °C) was compared, and the additivity of the effects of solutes was tested. The effects in iron aluminides with two solutes (V and Ti, Ti and Cr, V and Cr) are compared with those of a single solute V, Ti, and Cr. It is found that the additivity of yield stress increments is valid only for lower solute concentrations. When the amount of the solute atoms increases, the yield stress increment is substantially higher than the sum of the yield stress increments of single solutes. This behavior is related to the high-temperature order in iron aluminides.

Measurement of variation in soil solute tracer concentration across a range of effective pore sizes

USGS Publications Warehouse

Harvey, Judson W.

1993-01-01

Solute transport concepts in soil are based on speculation that solutes are distributed nonuniformly within large and small pores. Solute concentrations have not previously been measured across a range of pore sizes and examined in relation to soil hydrological properties. For this study, modified pressure cells were used to measure variation in concentration of a solute tracer across a range of pore sizes. Intact cores were removed from the site of a field tracer experiment, and soil water was eluted from 10 or more discrete classes of pore size. Simultaneous changes in water content and unsaturated hydraulic conductivity were determined on cores using standard pressure cell techniques. Bromide tracer concentration varied by as much as 100% across the range of pore sizes sampled. Immediately following application of the bromide tracer on field plots, bromide was most concentrated in the largest pores; concentrations were lower in pores of progressively smaller sizes. After 27 days, bromide was most dilute in the largest pores and concentrations were higher in the smaller pores. A sharp, threefold decrease in specific water capacity during elution indicated separation of two major pore size classes at a pressure of 47 cm H2O and a corresponding effective pore diameter of 70 μm. Variation in tracer concentration, on the other hand, was spread across the entire range of pore sizes investigated in this study. A two-porosity characterization of the transport domain, based on water retention criteria, only broadly characterized the pattern of variation in tracer concentration across pore size classes during transport through a macroporous soil.

[Changes in whole blood ionized magnesium concentration during cardiac surgery employing St. Thomas' cardioplegic solution].

PubMed

Chang, Kyung-ho; Bougaki, Masahiko; Kubota, Ryou; Tsubaki, Kumiko; Matsuo, Hideki; Hanaoka, Kazuo

2003-04-01

Although there is growing evidence to suggest that magnesium supplementation to patients undergoing cardiac surgery is beneficial, the way to administer magnesium is not established. Moreover in Japan St Thomas' cardioplegic solution, containing a high level of magnesium is widely used and the effect of such magnesium-rich cardioplegic solutions on blood magnesium concentration has not been well defined. We measured ionized magnesium concentrations (iMg) during cardiac surgery employing St Thomas' solution. Patients were divided into four groups. Group 1 patients were adults and group 2 were children, both of whom received St. Thomas' solution. Group 3 patients underwent cardiopulmonary bypass but did not receive any cardioplegic solution. Group 4 patients underwent off-pump coronary artery bypass grafting. In cardioplegia group (group 1 and 2) iMg was higher than the normal reference range at periods of rewarming, immediately postbypass, and at the end of the operation. iMg at immediately postbypass was related to the total amount of cardioplegic solution. In non-cardioplegia group (group 3 and 4) progressive decrease of iMg was observed throughout the operation. Because magnesium in cardioplegic solutions has substantial effect on perioperative iMg, it is crucial to measure iMg to avoid overdose of magnesium when magnesium-rich cardioplegic solutions are employed.

Direct molecular diffusion and micro-mixing for rapid dewatering of LiBr solution

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

Bigham, S; Isfahani, RN; Moghaddam, S

2014-03-01

A slow molecular diffusion rate often limits the desorption process of an absorbate molecule from a liquid absorbent. To enhance the desorption rate, the absorbent is often boiled to increase the liquid vapor interfacial area. However, the growth of bubbles generated during the nucleate boiling process still remains mass-diffusion limited. Here, it is shown that a desorption rate higher than that of boiling can be achieved, if the vapor absorbent interface is continuously replenished with the absorbate-rich solution to limit the concentration boundary layer growth. The study is conducted in a LiBr-water-solution, in which the water molecules' diffusion rate ismore » quite slow. The manipulation of the vapor solution interface concentration distribution is enabled by the mechanical confinement of the solution flow within microchannels, using a hydrophobic vapor-venting membrane and the implementation of microstructures on the flow channel's bottom wall. The microstructures stretch and fold the laminar streamlines within the solution film and produce vortices. The vortices continuously replace the concentrated solution at the vapor solution interface with the water-rich solution brought from the bottom and middle of the flow channel. The physics of the process is described using a combination of experimental and numerical studies. Published by Elsevier Ltd.« less

Solute and sediment export from Amazon forest and soybean headwater streams.

PubMed

Riskin, Shelby H; Neill, Christopher; Jankowski, KathiJo; Krusche, Alex V; McHorney, Richard; Elsenbeer, Helmut; Macedo, Marcia N; Nunes, Darlisson; Porder, Stephen

2017-01-01

Intensive cropland agriculture commonly increases streamwater solute concentrations and export from small watersheds. In recent decades, the lowland tropics have become the world's largest and most important region of cropland expansion. Although the effects of intensive cropland agriculture on streamwater chemistry and watershed export have been widely studied in temperate regions, their effects in tropical regions are poorly understood. We sampled seven headwater streams draining watersheds in forest (n = 3) or soybeans (n = 4) to examine the effects of soybean cropping on stream solute concentrations and watershed export in a region of rapid soybean expansion in the Brazilian state of Mato Grosso. We measured stream flows and concentrations of NO 3 - , PO 4 3- , SO 4 2- , Cl - , NH 4 + , Ca 2+ , Mg 2+ , Na + , K + , Al 3+ , Fe 3+ , and dissolved organic carbon (DOC) biweekly to monthly to determine solute export. We also measured stormflows and stormflow solute concentrations in a subset of watersheds (two forest, two soybean) during two/three storms, and solutes and δ 18 O in groundwater, rainwater, and throughfall to characterize watershed flowpaths. Concentrations of all solutes except K + varied seasonally in streamwater, but only Fe 3+ concentrations differed between land uses. The highest streamwater and rainwater solute concentrations occurred during the peak season of wildfires in Mato Grosso, suggesting that regional changes in atmospheric composition and deposition influence seasonal stream solute concentrations. Despite no concentration differences between forest and soybean land uses, annual export of NH 4 + , PO 4 3- , Ca 2+ , Fe 3+ , Na + , SO 4 2- , DOC, and TSS were significantly higher from soybean than forest watersheds (5.6-fold mean increase). This increase largely reflected a 4.3-fold increase in water export from soybean watersheds. Despite this increase, total solute export per unit watershed area (i.e., yield) remained low for all watersheds (<1 kg NO 3 - N·ha -1 ·yr -1 , <2.1 kg NH 4 + -N·ha -1 ·yr -1 , <0.2 kg PO 4 3- -P·ha -1 ·yr -1 , <1.5 kg Ca 2+ ·ha -1 ·yr -1 ). Responses of both streamflows and solute concentrations to crop agriculture appear to be controlled by high soil hydraulic conductivity, groundwater-dominated hydrologic flowpaths on deep soils, and the absence of nitrogen fertilization. To date, these factors have buffered streams from the large increases in solute concentrations that often accompany intensive croplands in other locations. © 2016 by the Ecological Society of America.

Uptake and translocation of plutonium in two plant species using hydroponics.

PubMed

Lee, J H; Hossner, L R; Attrep, M; Kung, K S

2002-01-01

This study presents determinations of the uptake and translocation of Pu in Indian mustard (Brassica juncea) and sunflower (Helianthus annuus) from Pu contaminated solution media. The initial activity levels of Pu were 18.50 and 37.00 Bq ml(-1), for Pu-nitrate [239Pu(NO3)4] and for Pu-citrate [239Pu(C6H5O7)+] in nutrient solution. Plutonium-diethylenetriaminepentaacetic acid (DTPA: [239Pu-C14H23O10N3] solution was prepared by adding 0, 5, 10, and 50 microg of DTPA ml(-1) with 239Pu(NO3)4 in nutrient solution. Concentration ratios (CR, Pu concentration in dry plant material/Pu concentration in nutrient solution) and transport indices (Tl, Pu content in the shoot/Pu content in the whole plant) were calculated to evaluate Pu uptake and translocation. All experiments were conducted in hydroponic solution in an environmental growth chamber. Plutonium concentration in the plant tissue was increased with increased Pu contamination. Plant tissue Pu concentration for Pu-nitrate and Pu-citrate application was not correlated and may be dependent on plant species. For plants receiving Pu-DTPA, the Pu concentration was increased in the shoots but decreased in the roots resulting in a negative correlation between the Pu concentrations in the plant shoots and roots. The Pu concentration in shoots of Indian mustard was increased for application rates up to 10 microg DTPA ml(-1) and up to 5 microg DTPA ml(-1) for sunflower. Similar trends were observed for the CR of plants compared to the Pu concentration in the shoots and roots, whereas the Tl was increased with increasing DTPA concentration. Plutonium in shoots of Indian mustard was up to 10 times higher than that in shoots of sunflower. The Pu concentration in the apparent free space (AFS) of plant root tissue of sunflower was more affected by concentration of DTPA than that of Indian mustard.

Degradation of organic pollutants in/on snow and ice by singlet molecular oxygen (¹O₂*) and an organic triplet excited state.

PubMed

Bower, Jonathan P; Anastasio, Cort

2014-04-01

Singlet molecular oxygen (¹O₂*) can be a significant sink for a variety of electron-rich pollutants in surface waters and atmospheric drops. We recently found that ¹O₂* concentrations are enhanced by up to a factor of 10(4) on illuminated ice compared to in the equivalent liquid solution, suggesting that ¹O₂* could be an important oxidant for pollutants in snow. To examine this, here we study the degradation of three model organic pollutants: furfuryl alcohol (to represent furans), tryptophan (for aromatic amino acids), and bisphenol A (for phenols). Each compound was studied in illuminated aqueous solution and ice containing Rose Bengal (RB, a sensitizer for ¹O₂*) and sodium chloride (to adjust the concentration of total solutes). The RB-mediated loss of each organic compound is enhanced on illuminated ice compared to in solution, by factors of 6400 for furfuryl alcohol, 8300 for tryptophan, and 50 for bisphenol A for ice containing 0.065 mM total solutes. Rates of loss of furfuryl alcohol and tryptophan decrease at a higher total solute concentration, in qualitative agreement with predictions from freezing-point depression. In contrast, the loss of bisphenol A on ice is independent of total solute concentration. Relative to liquid tests, the enhanced loss of tryptophan on ice during control experiments made with deoxygenated solutions and solutions in D₂O show that the triplet excited state of Rose Bengal may also contribute to loss of pollutants on ice.

Soil solution extraction techniques for microbial ecotoxicity testing: a comparative evaluation.

PubMed

Tiensing, T; Preston, S; Strachan, N; Paton, G I

2001-02-01

The suitability of two different techniques (centrifugation and Rhizon sampler) for obtaining the interstitial pore water of soil (soil solution), integral to the ecotoxicity assessment of metal contaminated soil, were investigated by combining chemical analyses and a luminescence-based microbial biosensor. Two different techniques, centrifugation and Rhizon sampler, were used to extract the soil solution from Insch (a loamy sand) and Boyndie (a sandy loam) soils, which had been amended with different concentrations of Zn and Cd. The concentrations of dissolved organic carbon (DOC), major anions (F- , CI-, NO3, SO4(2-)) and major cations (K+, Mg2+, Ca2+) in the soil solutions varied depending on the extraction technique used. Overall, the concentrations of Zn and Cd were significantly higher in the soil solution extracted using the centrifugation technique compared with that extracted using the Rhizon sampler technique. Furthermore, the differences observed between the two extraction techniques depended on the type of soil from which the solution was being extracted. The luminescence-based biosensor Escherichia coli HB101 pUCD607 was shown to respond to the free metal concentrations in the soil solutions and showed that different toxicities were associated with each soil, depending on the technique used to extract the soil solution. This study highlights the need to characterise the type of extraction technique used to obtain the soil solution for ecotoxicity testing in order that a representative ecotoxicity assessment can be carried out.

Improved levitation and trapping of particles by negative dielectrophoresis by the addition of amphoteric molecules

NASA Astrophysics Data System (ADS)

Flores-Rodriguez, Neftali; Markx, Gerard H.

2004-02-01

Addition of amphoteres could be used to improve the levitation and trapping of particles by negative dielectrophoresis. Addition of amphoteric molecules to electromanipulation media increases not only the permittivity of the medium and its viscosity but also its density. To investigate the effect of addition of amphoteres on levitation and trapping by negative dielectrophoresis, the electrokinetic behaviour of latex beads and viable yeast cells (Saccharomyces cerevisiae) was investigated in concentrated solutions of the amphoteric molecules N-[2-hydroxyethyl] piperazine-N'-[2-ethanesulfonic acid] (HEPES) and egr -aminocaproic acid (EACA) using different frequencies and voltages of the applied electrical signal and microelectrodes of different sizes. When using interdigitated electrodes without castellations, latex beads levitated an average of 43% higher when 0.67 M EACA solutions were used and a 54% higher after adding 0.67 M HEPES compared with the levitation heights when no amphoteres were added. Under the same conditions, yeast levitated 78% and 86% higher, respectively. At low voltages and low HEPES/EACA concentrations, the latex particles accumulated in bands between or above the electrodes. However, at the highest voltages and HEPES/EACA concentrations used, the particles formed a network of pearl chains above the electrode arrays. When using electrodes of the interdigitated castellated type of characteristic size 30 µm, latex particles levitated 32% and 40% higher when 0.67 M EACA and HEPES solutions were used in comparison with when no amphoteres were added. At these concentrations, the flow rate needed to dislodge the latex particles from the traps formed by the electric field pattern between the castellations of the interdigitated castellated electrodes was increased by 46% compared with the flow rate needed to achieve this when no amphoteres were added.

Effect of alpha/gamma phase ratio on corrosion behavior of dual-phase stainless steels.

PubMed

Lim, Y J; Reyes, M; Thongthammachat, S; Sukchit, K; Panich, M; Oshida, Y

1999-01-01

Dual-phase stainless steels have been developed in order to reduce the nickel content, which is potentially responsible to an allergic reaction when these steels are used as medical or dental applications. In this study, two different dual-phase stainless steels (2205 and Z100) were electrochemically tested to evaluate their corrosion resistance in three corrosive solutions (i.e., synthetic saliva, 0.9% NaCl solution, and Ringer solution). Particularly, an attempt was made to correlate the corrosion resistance to a metallographic parameter, which is, in this study, the alpha/gamma phase ratio. It was concluded that (1) type 2205 stainless steel exhibited excellent corrosion resistance in all three corrosion media; however 2205 stainless steel decreases its corrosion resistance by increasing chloride concentration in tested electrolytes from synthetic saliva through 0.9% NaCl solution to Ringer solution. (2) X-ray diffraction analysis indicated that the alpha/gamma phase ratio of 2205 (1.735) was higher than that of Z100 (0.905). As a result, it is suggested that by increasing the alpha/gamma phase ratio the material shows more corrosion-prone behavior when being subjected to a hostile environment containing higher chloride ion concentration.

Effects of ions on the solubility transition and the phase-separation of N-isopropylacrylamide in water.

PubMed

Sasaki, Shigeo; Okabe, Satoshi

2011-11-10

The effects of NaCl, NaOH, and HCl on the solubility transition and the phase-separation of N-isopropylacrylamide (NIPA) were investigated for the purpose of clarifying the physicochemical mechanism of salting-out and salting-in phenomena. The discrete change in the solubility of NIPA in the salt-free water at the solubility transition (reported in J. Phys. Chem. B 2010, 114, 14995-15002) decreased with the addition of HCl and disappeared in the HCl solutions at concentrations higher than 2 M, while it increased with additions of NaOH and NaCl. A difference in NIPA concentration between the phase-separated solutions decreases with the addition of HCl and increases with additions of NaOH and NaCl. Partition coefficients of HCl in the phase-separated NIPA-rich solutions are higher than those in the NIPA poor solutions, while partition coefficients of NaCl and NaOH between the NIPA-rich and -poor solutions have trends opposite to those of HCl. The present results clearly indicate that the HCl favors the dehydrated NIPA and stabilizes the H(2)O-poor state of the NIPA molecule more than NaCl.

Stress concentration in a cylindrical shell containing a circular hole.

NASA Technical Reports Server (NTRS)

Adams, N. J. I.

1971-01-01

The state of stress in a cylindrical shell containing a circular cutout was determined for axial tension, torsion, and internal pressure loading. The solution was obtained for the shallow shell equations by a variational method. The results were expressed in terms of a nondimensional curvature parameter which was a function of shell radius, shell thickness, and hole radius. The function chosen for the solution was such that when the radius of the cylindrical shell approaches infinity, the flat-plate solution was obtained. The results are compared with solutions obtained by more rigorous analytical methods, and with some experimental results. For small values of the curvature parameter, the agreement is good. For higher values of the curvature parameter, the present solutions indicate a limiting value of stress concentration, which is in contrast to previous results.

Arsenic in the rhizosphere soil solution of ferns.

PubMed

Wei, Chaoyang; Zheng, Huan; Yu, Jiangping

2012-12-01

The aim of this study was to explore the evidence of arsenic hyperaccumulation in plant rhizosphere solutions. Six common fern plants were selected and grown in three types of substrate: arsenic (As) -tailings, As-spiked soil, and soil-As-tailing composites. A rhizobox was designed with an in-situ collection of soil solutions to analyze changes in the As concentration and valence as well as the pH, dissolved organic carbon (DOC) and total nitrogen (TN). Arsenite composed less than 20% of the total As, and As depletion was consistent with N depletion in the rhizosphere solutions of the various treatments. The As concentrations in the rhizosphere and non-rhizosphere solutions in the presence of plants were lower than in the respective controls without plants, except for in the As-spiked soils. The DOC concentrations were invariably higher in the rhizosphere versus non-rhizosphere solutions from the various plants; however, no significant increase in the DOC content was observed in Pteris vittata, in which only a slight decrease in pH appeared in the rhizosphere compared to non-rhizosphere solutions. The results showed that As reduction by plant roots was limited, acidification-induced solubilization was not the mechanism for As hyperaccumulation.

Determination of Halide Concentrations at the Interface of Zwitterionic Micelles by Chemical Trapping: Influence of the Orientation of the Dipole and the Nature of the Cation.

PubMed

Cuccovia; Romsted; Chaimovich

1999-12-01

The interfacial concentrations of Cl(-) and Br(-) in aqueous zwitterionic micelles were determined by chemical trapping by analyzing product yields from spontaneous dediazoniation of micelle-bound 2,6-dimethyl-4-hexadecylbenzenediazonium ion. Interfacial concentrations of Cl(-) and Br(-) in 3-(N-hexadecyl-N, N-dimethylammonio) propane sulfonate, HPS, micelles were higher than in bulk solutions prepared with Li(+), Na(+), Rb(+), Cs(+), tetramethylammonium (TMA(+)), Mg(+2), and Ca(+2) salts. In contrast, the interfacial concentrations of Cl(-) and Br(-) were generally lower than in bulk solution in hexadecylphosphoryl choline, HDPC, micelles for all salts except Mg(+2) and Ca(+2). In both HPS and HDPC micelles the interfacial concentration of Br(-) was higher than that of Cl(-), showing that binding is anion selective. The cation had a large effect on the interfacial concentration of halide ions with HDPC micelles decreasing in the order Ca(2+) > Mg(2+) > Li(+) > Na(+) > K(+) > Cs(+) > Rb(+) > TMA(+). These results are the first direct and extensive determination of local halide ion concentration at the surface of zwitterionic micelles, and they demonstrate that chemical trapping methodology will work in membranes at physiologically relevant salt concentrations. Copyright 1999 Academic Press.

Superactivity of peroxidase solubilized in reversed micellar systems.

PubMed

Setti, L; Fevereiro, P; Melo, E P; Pifferi, P G; Cabral, J M; Aires-Barros, M R

1995-12-01

Vaccinium mirtyllus peroxidase solubilized in reversed micelles was used for the oxidation of guaiacol. Some relevant parameters for the enzymatic activity, such as pH, w(o) (molar ratio water/surfactant), surfactant type and concentration, and cosurfactant concentration, were investigated. The peroxidase showed higher activities in reversed micelles than in aqueous solution. The stability of the peroxidase in reversed micelles was also studied, namely, the effect of w(o) and temperature on enzyme deactivation. The peroxidase displayed higher stabilities in CTAB/hexanol in isooctane reversed micelles, with half-life times higher than 500 h.

Rheological Behavior Xanthan and SlurryPro Polymer Solutions Evaluated as Shear Thinning Delivery Fluids for Subsurface Remediation

NASA Astrophysics Data System (ADS)

Zhong, L.; Oostrom, M.; Truex, M.; Vermeul, V.

2011-12-01

Shear thinning fluids can be applied as a delivery means to enhance the uniformity of remedial amendment distribution in heterogeneous aquifers, thereby to improve remediation performance. The rheological behavior of biopolymer xanthan gum and synthetic polymer SlurryPro were tested, and their influence on the amendment delivery performance was evaluated. The impact of polymer concentration, basic water chemistry, salinity (e.g., Br-, Na+, Ca2+ concentrations), remedial amendments (phosphate, sodium lactate, ethyl lactate, lactate oil, whey), sediments, and the mixing approach on the rheological properties of the polymer solutions was determined. The SlurryPro polymer lost shear-thinning properties even at relatively low solution ionic strength. However, the xanthan gum polymer maintained shear-thinning properties under most of the tested conditions, though with some loss in absolute viscosity with increasing ionic strength. Xanthan appeared to be the better candidate for enhanced amendment delivery. Increasing in xanthan concentration not only increased the solution viscosity, but also increased degree of shear thinning. Addition of salt decreased the solution viscosity and the degree of shear thinning, while the influence was diminished when the polymer concentration was higher. After reaching a critical xanthan concentration, addition of salt increased solution viscosity. The degradation of xanthan and SlurryPro in the presence of site aquifer materials and microbes was studied in batch tests in which the field sediment/water ratio was simulated. The viscosity of the polymer solutions dropped 85% or more in the first week, while the solution chemical oxygen demand (COD) decreasing occurred at a much slower rate.

Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

PubMed

Delbem, Alberto Carlos Botazzo; Souza, José Antonio Santos; Zaze, Ana Carolina Soares Fraga; Takeshita, Eliana Mitsue; Sassaki, Kikue Takebayashi; Moraes, João Carlos Silos

2014-01-01

The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite.

Organic Carbon Release from Groundwater Sediments under Changing Geochemical Conditions

NASA Astrophysics Data System (ADS)

Tinnacher, R. M.; Bhattacharyya, A.; Fox, P. M.; Nico, P. S.

2016-12-01

Due to climate change, local weather patterns are expected to change, especially with respect to precipitation, the frequency of extreme storm water events, and `drought-like' conditions. This in turn, may affect groundwater recharge, the geochemical conditions in natural groundwater systems, and the chemical and microbiological processes involved in organic matter degradation. Besides the complexity of organic matter structures and local limitations in nutrients, the association of organic carbon with sediment minerals can strongly limit organic matter bioaccessability and degradability. In this study, we investigate how variations in groundwater chemistry, e.g. with respect to dissolved CO2 concentrations, may potentially affect the release of natural organic carbon from groundwater sediments, and render organic matter more bioaccessible. In lab-scale experiments under anaerobic conditions, aquifer sediments from the floodplain of the Colorado River (Rifle, USA) were brought into contact with fresh, organic-carbon free groundwater solutions, at natural or reduced CO2 concentration levels. During the repeated exchange of solutions at two temperature settings (room-temperature and 4 °C), supernatant solutions were characterized in terms of pH, dissolved metal and organic carbon (OC) concentrations, and potential changes in released OC characteristics. Sediment samples were evaluated for possible differences in Fe-speciation before and after the experiment based on EXAFS (bulk Fe K-edge). Preliminary results for 20 exchanges of groundwater solutions show a repeated release of low OC concentrations ( 0.5-2 mg OC/g sediment; 0.05-0.2% of sediment-associated OC) without any apparent depletion in the overall source term over 50 days. After 14 days, room-temperature samples released slightly higher OC concentrations than samples kept at 4 °C. An increase in solution pH, after switching to a `CO2-free' groundwater solution, did not trigger a higher OC release. Last, specific UV absorbance measurements for room-temperature samples suggest changes in released OC characteristics due to repeated solution exchanges. Additional sample characterization is ongoing, with the goal to elucidate potential changes in released OC characteristics over the course of the experiment.

Reactions of Starch in Ionic Liquids

USDA-ARS?s Scientific Manuscript database

We found that starches are found to be soluble at 80 ºC in ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-butyl-3-methylimidazolium dicyanamide (BMIMdca) in concentration up to 10% (w/w). Higher concentrations of biopolymers in these novel solvents resulted in solutions w...

Higher concentration local anaesthetics causing prolonged anaesthesia. Do they? A literature review and case reports.

PubMed

Kingon, A; Sambrook, P; Goss, A

2011-12-01

Higher concentration dental local anaesthetics (3% and 4%) have become more available in Australia in recent years. Benefits claimed include a faster onset of anaesthesia and improved success with injections compared to 2% solutions. Recent reports suggest that the higher concentration carries a greater risk of prolonged anaesthesia to the mandibular and particularly the lingual nerves. The literature was reviewed and those studies which demonstrated adverse effects of different concentrations of local anaesthetics were analysed. Recent cases are presented. There is an extensive international literature which confirms increased concentration of local anaesthetic does show an increased risk, by about ×6, of prolonged anaesthesia. Five case reports illustrate the impact of this complication on patients' quality of life. Careful consideration needs to be given before using higher concentration local anaesthetic agents for mandibular and lingual blocks as lower concentration local anaesthetics are safer. If acceptable to individual patients, avoidance of block injections or any local anaesthetic for minor restorative tasks could be encouraged given the severity of the complication. It is safe to use the higher concentration agents for infiltrations away from major nerves. © 2011 Australian Dental Association.

High Endogenous Salivary Amylase Activity Is Associated with Improved Glycemic Homeostasis following Starch Ingestion in Adults123

PubMed Central

Mandel, Abigail L.

2012-01-01

In the current study, we determined whether increased digestion of starch by high salivary amylase concentrations predicted postprandial blood glucose following starch ingestion. Healthy, nonobese individuals were prescreened for salivary amylase activity and classified as high (HA) or low amylase (LA) if their activity levels per minute fell 1 SD higher or lower than the group mean, respectively. Fasting HA (n = 7) and LA (n = 7) individuals participated in 2 sessions during which they ingested either a starch (experimental) or glucose solution (control) on separate days. Blood samples were collected before, during, and after the participants drank each solution. The samples were analyzed for plasma glucose and insulin concentrations as well as diploid AMY1 gene copy number. HA individuals had significantly more AMY1 gene copies within their genomes than did the LA individuals. We found that following starch ingestion, HA individuals had significantly lower postprandial blood glucose concentrations at 45, 60, and 75 min, as well as significantly lower AUC and peak blood glucose concentrations than the LA individuals. Plasma insulin concentrations in the HA group were significantly higher than baseline early in the testing session, whereas insulin concentrations in the LA group did not increase at this time. Following ingestion of the glucose solution, however, blood glucose and insulin concentrations did not differ between the groups. These observations are interpreted to suggest that HA individuals may be better adapted to ingest starches, whereas LA individuals may be at greater risk for insulin resistance and diabetes if chronically ingesting starch-rich diets. PMID:22492122

Ethylene glycol assisted spray pyrolysis for the synthesis of hollow BaFe12O19 spheres

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

Xu, X; Park, J; Hong, YK

2015-04-01

Hollow spherical BaFe12O19 particles were synthesized by spray pyrolysis from a solution containing ethylene glycol (EG) and precursors at 1000 degrees C. The effects of EG concentration on particle morphology, crystallinity and magnetic properties were investigated. The hollow spherical particles were found to consist of primary particles, and higher EG concentration led to a bigger primary particle size. EG concentration did not show much effect on the hollow particle size. Better crystallinity and higher magnetic coercivity were obtained with higher EG concentration, which is attributed to further crystallization with the heat produced from EG combustion. Saturation magnetization (emu/g) decreased withmore » increasing EG concentration due to residual carbon from EG incomplete combustion, contributing as a non-magnetic phase to the particles. Published by Elsevier B.V.« less

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

PubMed

Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

2016-02-01

In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

Surface modification of thin film composite reverse osmosis membrane by glycerol assisted oxidation with sodium hypochlorite

NASA Astrophysics Data System (ADS)

Raval, Hiren D.; Samnani, Mohit D.; Gauswami, Maulik V.

2018-01-01

Need for improvement in water flux of thin film composite (TFC) RO membrane has been appreciated by researchers world over and surface modification approach is found promising to achieve higher water flux and solute rejection. Thin film composite RO membrane was exposed to 2000 mg/l sodium hypochlorite solution with varying concentrations of glycerol ranging from 1 to 10%. It was found that there was a drop in concentration of sodium hypochlorite after the addition of glycerol because of a new compound resulted from the oxidation of glycerol with sodium hypochlorite. The water flux of the membrane treated with 1% glycerol with 2000 mg/l sodium hypochlorite for 1 h was about 22% more and salt rejection was 1.36% greater than that of only sodium hypochlorite treated membrane for the same concentration and time. There was an increase in salt rejection of membrane with increase in concentration of glycerol from 1% to 5%, however, increasing glycerol concentration further up to 10%, the salt rejection declined. The water flux was found declining from 1% glycerol solution to 10% glycerol solution. The membrane samples were characterized to understand the change in chemical structure and morphology of the membrane.

Major-ion chemistry of the Rocky Mountain snowpack, USA

USGS Publications Warehouse

Turk, J.T.; Taylor, Howard E.; Ingersoll, G.P.; Tonnessen, K.A.; Clow, D.W.; Mast, M.A.; Campbell, D.H.; Melack, J.M.

2001-01-01

During 1993-97, samples of the full depth of the Rocky Mountain snowpack were collected at 52 sites from northern New Mexico to Montana and analyzed for major-ion concentrations. Concentrations of acidity, sulfate, nitrate, and calcium increased from north to south along the mountain range. In the northern part of the study area, acidity was most correlated (negatively) with calcium. Acidity was strongly correlated (positively) with nitrate and sulfate in the southern part and for the entire network. Acidity in the south exceeded the maximum acidity measured in snowpack of the Sierra Nevada and Cascade Mountains. Principal component analysis indicates three solute associations we characterize as: (1) acid (acidity, sulfate, and nitrate), (2) soil (calcium, magnesium, and potassium), and (3) salt (sodium, chloride, and ammonium). Concentrations of acid solutes in the snowpack are similar to concentrations in nearby wetfall collectors, whereas, concentrations of soil solutes are much higher in the snowpack than in wetfall. Thus, dryfall of acid solutes during the snow season is negligible, as is gypsum from soils. Snowpack sampling offers a cost-effective complement to sampling of wetfall in areas where wetfall is difficult to sample and where the snowpack accumulates throughout the winter. Copyright ?? 2001 .

Uptake of perfluorinated compounds by plants grown in nutrient solution.

PubMed

García-Valcárcel, A I; Molero, E; Escorial, M C; Chueca, M C; Tadeo, J L

2014-02-15

The uptake rates of three perfluorinated carboxylates and three perfluorinated sufonates by a grass (B diandrus) grown in nutrient solution at two different perfluorinated compounds (PFCs) concentrations were assessed. Grass can be ingested by grazing animals causing the PFCs to enter the food chain, which is a pathway of human exposure to these compounds. A rapid and miniaturized method was developed to determine PFCs in plants, based on a matrix solid-phase dispersion (MSPD) extraction procedure followed by quantitation by HPLC-MS/MS with an MQL in the range from 1 to 9 ng/g. An increase of PFCs levels in plant was observed along the exposure time. Differences in uptake for studied perfluorinated carboxylates were found, showing a decrease with carbon chain length (from 3027 to 1,167 ng/g at the end of assay), whereas no significant differences in absorption were obtained between perfluorinated sulfonates (about 1,700 ng/g). Initially, higher PFC transfer factors (ratio between concentration in plant and concentration in initial nutrient solution) were obtained for plants growing in the nutrient solution at the highest PFC concentration, but these factors became similar with time to plants exposed to the lowest concentration. © 2013 Elsevier B.V. All rights reserved.

Effect of Carboxylmethyl Cellulose Coating and Osmotic Dehydration on Freeze Drying Kinetics of Apple Slices

PubMed Central

Rahimi, Jamshid; Singh, Ashutosh; Adewale, Peter Olusola; Adedeji, Akinbode A.; Ngadi, Michael O.; Raghavan, Vijaya

2013-01-01

The effect of different concentrations of sugar solution (hypertonic) (30%, 45% and 60% w/v) and carboxyl methyl cellulose (CMC) (0%, 1% and 2% w/v) coating on freeze drying of apple slices was studied. In total, nine treatments with respect to concentrations of hypertonic solution and coating layer were prepared to analyze their influence on the physical and chemical properties of freeze dried apple slices. It was observed that increase in the sugar solution concentration, decreased the moisture content of the apple slices significantly impacting its water activity, texture and sugar gain. Application of different concentrations of CMC coating had no significant effect on the properties of dried apple slices. A significant change was observed for color of CMC coated freeze dried apple slices pretreated with 60% sugar solution. Drying kinetics of pretreated apple slices were fitted by using two drying models, Newton’s and Page’s. Page’s model showed higher R-square and lower root mean square error (RSME) compared to Newton’s model. PMID:28239107

Polymeric films loaded with cisplatin for malignant pleural mesothelioma: a pharmacokinetic study in an ovine model

PubMed Central

Barocelli, Elisabetta; Cavazzoni, Andrea; Petronini, Piergiorgio; Mucchino, Claudio; Cantoni, Anna Maria; Leonardi, Fabio; Ventura, Luigi; Barbieri, Stefano; Colombo, Paolo; Fusari, Antonella; Carbognani, Paolo; Rusca, Michele; Sonvico, Fabio

2018-01-01

Background Malignant pleural mesothelioma (MPM) continues to be a distressing tumor due to its aggressive biologic behavior and scanty prognosis. Several therapeutic approaches have been tested both in clinical and preclinical settings, being intrapleural chemotherapy one of the most promising. Some years ago, our interest focused on polymeric films loaded with cisplatin for the adjuvant intrapleural treatment of surgical patients. After in vitro and in vivo studies in a rat recurrence model of MPM, the aim of this study was to evaluate the pharmacokinetics of the polymeric films in a sheep model in view of further studies in a clinical setting. Methods An ovine model was used. Animals were divided into four groups according to pharmacologic treatment: control group (three animals undergoing left pneumonectomy and saline-NaCl solution); intrapleural hyaluronate cisplatin films (HYALCIS) group (six animals undergoing left pneumonectomy and intrapleural application of polymeric films loaded with cisplatin); intrapleural cisplatin solution (six animals undergoing left pneumonectomy and intrapleural application of cisplatin solution); intravenous cisplatin (five animals undergoing left pneumonectomy and intravenous administration of cisplatin solution). The primary objective was the plasmatic and pleural concentration of cisplatin in the treatment groups. The secondary objective was the treatment-related toxicity evaluated by plasmatic analysis performed at prearranged time intervals and histological examinations of tissue samples collected during animal autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups. Results Twenty female Sardinian sheep with a mean weight of 45.1 kg were studied. All animals survived the surgical procedures. The whole surgical procedure had a mean duration of 113 minutes. Cisplatin blood levels obtained from polymeric films application were low during the first 24 hours after the application; then, the cisplatin blood level increased gradually and progressively until it reached significantly higher plasmatic concentrations after 120 hours compared to intrapleural cisplatin solution (P=0.004) and intravenous administration (P=0.001), respectively. Considering cisplatin concentration at 168 hours after the application, animals treated with polymeric films had higher plasmatic values than animals treated with intrapleural cisplatin solution and intravenous cisplatin (P=0.001). Despite the high cisplatin plasmatic concentrations, treatment related-toxicity towards kidneys and liver was comparatively lower compared to the intravenous and intrapleural cisplatin administration and closer to the control levels. Conclusions Polymeric films loaded with cisplatin allowed to reach significantly higher intrapleural and plasmatic cisplatin concentrations compared to intrapleural and intravenous cisplatin solution, providing at the same time, a significant reduction of treatment related toxicity. PMID:29507788

Polymeric films loaded with cisplatin for malignant pleural mesothelioma: a pharmacokinetic study in an ovine model.

PubMed

Ampollini, Luca; Barocelli, Elisabetta; Cavazzoni, Andrea; Petronini, Piergiorgio; Mucchino, Claudio; Cantoni, Anna Maria; Leonardi, Fabio; Ventura, Luigi; Barbieri, Stefano; Colombo, Paolo; Fusari, Antonella; Carbognani, Paolo; Rusca, Michele; Sonvico, Fabio

2018-01-01

Malignant pleural mesothelioma (MPM) continues to be a distressing tumor due to its aggressive biologic behavior and scanty prognosis. Several therapeutic approaches have been tested both in clinical and preclinical settings, being intrapleural chemotherapy one of the most promising. Some years ago, our interest focused on polymeric films loaded with cisplatin for the adjuvant intrapleural treatment of surgical patients. After in vitro and in vivo studies in a rat recurrence model of MPM, the aim of this study was to evaluate the pharmacokinetics of the polymeric films in a sheep model in view of further studies in a clinical setting. An ovine model was used. Animals were divided into four groups according to pharmacologic treatment: control group (three animals undergoing left pneumonectomy and saline-NaCl solution); intrapleural hyaluronate cisplatin films (HYALCIS) group (six animals undergoing left pneumonectomy and intrapleural application of polymeric films loaded with cisplatin); intrapleural cisplatin solution (six animals undergoing left pneumonectomy and intrapleural application of cisplatin solution); intravenous cisplatin (five animals undergoing left pneumonectomy and intravenous administration of cisplatin solution). The primary objective was the plasmatic and pleural concentration of cisplatin in the treatment groups. The secondary objective was the treatment-related toxicity evaluated by plasmatic analysis performed at prearranged time intervals and histological examinations of tissue samples collected during animal autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups. Twenty female Sardinian sheep with a mean weight of 45.1 kg were studied. All animals survived the surgical procedures. The whole surgical procedure had a mean duration of 113 minutes. Cisplatin blood levels obtained from polymeric films application were low during the first 24 hours after the application; then, the cisplatin blood level increased gradually and progressively until it reached significantly higher plasmatic concentrations after 120 hours compared to intrapleural cisplatin solution (P=0.004) and intravenous administration (P=0.001), respectively. Considering cisplatin concentration at 168 hours after the application, animals treated with polymeric films had higher plasmatic values than animals treated with intrapleural cisplatin solution and intravenous cisplatin (P=0.001). Despite the high cisplatin plasmatic concentrations, treatment related-toxicity towards kidneys and liver was comparatively lower compared to the intravenous and intrapleural cisplatin administration and closer to the control levels. Polymeric films loaded with cisplatin allowed to reach significantly higher intrapleural and plasmatic cisplatin concentrations compared to intrapleural and intravenous cisplatin solution, providing at the same time, a significant reduction of treatment related toxicity.

Study of the uptake by duckweed of aluminum, copper, and lead from aqueous solution

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

Mo, S.C.; Choi, D.S.; Robinson, J.W.

1988-01-01

THE UPTAKE OF AL/sup 3 +/, CU/sup 2 +/, AND PB/sup 2 +/ FROM AQUEOUS SOLUTION BY DUCKWEED HAS BEEN OBSERVED AT PH 4.0, 4.5, AND 5.0. THE RESULTS SHOWED THAT THE UPTAKE OF PB/sup 2 +/ WAS MUCH FASTER THAN AL/sup 3 +/ AND CU/sup 2 +/. THE UPTAKE OF CU/sup 2 +/ WAS SUPPRESSED BY THE PRESENCE OF PB/sup 2 +/ AND AL/sup 3 +/. THE PROPORTION OF METAL UPTAKE (PMUT) BY DUCKWEED WAS DEPENDENT ON THE METAL CONCENTRATION IN THE SOLUTION WHEN ONLY ONE KIND OF METAL ION WAS PRESENT. IT WAS DECREASED BY INCREASING CONCENTRATIONS OFmore » OTHER METALS IN MIXTURES OF SOLUTIONS. THE METAL UPTAKE BY THE DUCKWEED WAS ALWAYS LESS THAN THE LOSS OF METAL CONTENT IN THE RELEVANT SOLUTION. THIS FACT IMPLIED THAT THE PROCESS OF THE UPTAKE OF METAL IONS BY THE DUCKWEED MAY INVOLVE TWO STAGES. IN THE FIRST, THE METAL IS ABSORBED BUT THEN LATER IT IS ADSORBED BY THE DUCKWEED. THE ALUMINUM ION WAS FOUND TO BE MORE TOXIC THAN THE COPPER ION AT LOWER PH AND HIGHER CONCENTRATION, BUT THE SITUATION IS REVERSED AT HIGHER PH. A POSSIBLE EXPLANATION OF TOXICITY OF CU/sup 2 +/ AND AL/sup 3 +/ IN CHLOROPHYLL WAS REPLACED BY THE CU/sup 2 +/ OR AL/sup 3 +/. THIS MAY LEAD THE CHLOROPHYLL TO LOSE ITS NORMAL ACTIVITY AND KILL THE DUCKWEED.« less

Reduction of rewarming injury of the hepatic graft by a heat insulator.

PubMed

Wakiyama, S; Yanaga, K; Soejima, Y; Nishizaki, T; Sugimachi, K

1997-04-01

The deleterious effect of rewarming in orthotopic liver transplantation is recognized. This study examined the significance of rewarming the hepatic allograft, and the possibility of using a heat insulator to reduce rewarming injury. After total hepatectomy in rats with in situ perfusion by chilled (4 degrees C) lactated Ringer's solution, the livers were divided into four groups of ten each: group 1, 4-h preservation in chilled Ringer's solution and 15 min of rewarming; group 2, 6-h preservation in chilled Ringer's solution; group 3, 6-h preservation in chilled Ringer's solution and 15 min of rewarming; group 4, 6-h preservation in chilled Ringer's solution and 15 min of rewarming with a heat insulator. Glutamic-pyruvic transaminase (GPT) and N-acetyl-beta-glucosaminidase (NAG) concentrations in the final graft effluent, and the amount of adenosine 5'-triphosphate (ATP) in liver tissue after preservation, were measured. GPT and NAG concentrations in the final graft effluent of group 3 were higher than those of group 2 (P < 0.01), whereas values in group 4 were lower than those of group 3 (P < 0.05). The final ATP concentration in group 3 was significantly lower than that in group 2 (P < 0.01), whereas the value in group 4 was significantly higher than that of group 3 (P < 0.01). Rewarming diminishes the viability of a liver graft with degradation of ATP, and a heat insulator reduces rewarming injury.

Concentration of Nitrate near the Surface of Frozen Salt Solutions

NASA Astrophysics Data System (ADS)

Michelsen, R. R. H.; Marrocco, H. A.

2017-12-01

The photolysis of nitrate near the surface of snow and ice in Earth's environment results in the emission of nitrogen oxides (NO, NO2 and, in acidic snow, HONO) and OH radicals. As a result, nitrate photolysis affects the composition and oxidative capacity of the overlying atmosphere. Photolysis yields depend in part on how much nitrate is close enough to the surface to be photolyzed. These concentrations are assumed to be higher than the concentrations of nitrate that are measured in melted snow and ice samples. However, near-surface concentrations of nitrate have not been directly measured. In this work, laboratory studies of the concentration of nitrate in frozen aqueous solutions are described. Individual aqueous solutions of nitric acid, sodium nitrate, and magnesium nitrate were mixed. Attenuated total reflection infrared spectroscopy was utilized to measure the nitrate and liquid water signals within 200 - 400 nm of the lower surface of frozen samples. Temperature was varied from -18°C to -2°C. In addition to the amount of nitrate observed, changes to the frozen samples' morphology with annealing are discussed. Nitrate concentrations near the lower surface of these frozen solutions are high: close to 1 M at warmer temperatures and almost 4 M at the coldest temperature. Known freezing point depression data describe the observed concentrations better than ideal solution thermodynamics, which overestimate concentration significantly at colder temperatures. The implications for modeling the chemistry of snow are discussed. Extending and relating this work to the interaction of gas-phase nitric acid with the surfaces of vapor-deposited ice will also be explored.

Natural colloidal P and its contribution to plant P uptake.

PubMed

Montalvo, Daniela; Degryse, Fien; McLaughlin, Mike J

2015-03-17

Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P.

Factorial analysis of the trihalomethane formation in the reaction of colloidal, hydrophobic, and transphilic fractions of DOM with free chlorine.

PubMed

Platikanov, Stefan; Tauler, Roma; Rodrigues, Pedro M S M; Antunes, Maria Cristina G; Pereira, Dilson; Esteves da Silva, Joaquim C G

2010-09-01

This study focuses on the factors that affect trihalomethane (THMs) formation when dissolved organic matter (DOM) fractions (colloidal, hydrophobic, and transphilic fractions) in aqueous solutions were disinfected with chlorine. DOM fractions were isolated and fractionated from filtered lake water and were characterized by elemental analysis. The investigation involved a screening Placket-Burman factorial analysis design of five factors (DOM concentration, chlorine dose, temperature, pH, and bromide concentration) and a Box-Behnken design for a detailed assessment of the three most important factor effects (DOM concentration, chlorine dose, and temperature). The results showed that colloidal fraction has a relatively low contribution to THM formation; transphilic fraction was responsible for about 50% of the chloroform generation, and the hydrophobic fraction was the most important to the brominated THM formation. When colloidal and hydrophobic fraction solutions were disinfected, the most significant factors were the following: higher DOM fraction concentration led to higher THM concentration, an increase of pH corresponded to higher concentration levels of chloroform and reduced bromoform, higher levels of chlorine dose and temperature produced a rise in the total THM formation, especially of the chlorinated THMs; higher bromide concentration generates higher concentrations of brominated THMs. Moreover, linear models were implemented and response surface plots were obtained for the four THM concentrations and their total sum in the disinfection solution as a function of the DOM concentration, chlorine dose, and temperature. Overall, results indicated that THM formation models were very complex due to individual factor effects and significant interactions among the factors. In order to reduce the concentration of THMs in drinking water, DOM concentrations must be reduced in the water prior to the disinfection. Fractionation of DOM, together with an elemental analysis of the fractions, is important issue in the revealing of the quality and quantity characteristics of DOM. Systematic study composed from DOM fraction investigation and factorial analysis of the responsible parameters in the THM formation reaction can, after an evaluation of the adjustment of the models with the reality, serves well for the evaluation of the spatial and temporal variability in the THM formation in dependence of DOM. However, taking into consideration the natural complexity of DOM, different operations and a strict control of them (like coagulation/flocculation and filtration) has to be used to quantitatively remove DOM from the raw water. Assuming that this study represents a local case study, similar experiments can be easily applied and will supply with relevant information every local water treatment plant meeting problems with THM formation. The coagulation/flocculation and the filtration stages are the main mechanisms to remove DOM, particularly the colloidal DOM fraction. With the objective to minimize THMs generation, different unit operation designed to quantitatively remove DOM from water must be optimized.

Trimerization Dictates Solution Opalescence of a Monoclonal Antibody.

PubMed

Yang, Teng-Chieh; Langford, Alex Jacob; Kumar, Sandeep; Ruesch, John Carl; Wang, Wei

2016-08-01

Opalescence, sometimes observed in antibody solutions, is thought to be mediated by light scattering of soluble oligomers or insoluble particulates. However, mechanistic features, such as stoichiometry and self-association affinity of oligomeric species related to opalescence, are poorly understood. Here, opalescence behavior of a monoclonal antibody (mAb-1) solution was studied over a wide range of solution conditions including different protein concentrations, pH, and in the presence or absence of salt. Hydrodynamic and thermodynamic properties of mAb-1 solutions were studied by analytical ultracentrifugation and dynamic light scattering. Opalescence in mAb-1 solutions is pH and concentration dependent. The degree of opalescence correlates with reversible monomer-trimer equilibrium detected by analytical ultracentrifugation. Increased trimer formation corresponds to increased opalescence in mAb-1 solutions at higher pH and protein concentrations. Addition of NaCl shifts this equilibrium toward monomer and reduces solution opalescence. This study demonstrates that opalescence in mAb-1 solutions does not arise from the light scattering of monomer or random molecular self-associations but is strongly correlated with a specific self-association stoichiometry and affinity. Importantly, at pH 5.5 (far below isoelectric point of mAb-1), the solution is not opalescent and with nonideal behavior. This study also dissects several parameters to describe the hydrodynamic and thermodynamic nonideality. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Potassium concentration effect on growth, gas exchange and mineral accumulation in potatoes

NASA Technical Reports Server (NTRS)

Cao, W.; Tibbitts, T. W.

1991-01-01

This study was conducted to evaluate the responses of potatoes to six K solution concentrations maintained with a flow-through nutrient film system. Potato plants were grown for 42 days in sloping shallow trays containing a 1 cm layer of quartz gravel with a continuous flow of 4 ml min-1 of nutrient solutions having K concentrations of 0.10, 0.55, 1.59, 3.16, 6.44, 9.77 meq L-1. Plant leaf area, total and tuber dry weights were reduced over 25% at 0.10 meq L-1 of K and over 17% at 9.77 meq L-1 of K compared to concentrations of 0.55, 1.59, 3.16 and 6.44 meq L-1 of K. Gas exchange measurements on leaflets in situ after 39 days of growth demonstrated no significant differences among different K treatments in CO2 assimilation rate, stomatal conductance, intercellular CO2 concentration, and transpiration. Further measurements made only on plants grown at 0.10, 1.59, 6.44 meq L-1 of K showed similar responses of CO2 assimilation rate to different intercellular CO2 concentrations. This suggested that the photosynthetic systems were not affected by different K nutrition. The leaves of plants accumulated about 60% less K at 0.10 meq L-1 of K than at higher K concentrations. However, Ca and Mg levels in the leaves were higher at 0.10 meq L-1 of K than at higher K concentrations. This indicates that low K nutrition not only reduced plant growth, but also affected nutrient balance between major cations.

Preferential solvatation of human serum albumin in dimethylsulfoxide-H2O binary solution

NASA Astrophysics Data System (ADS)

Grigoryan, K. R.

2009-12-01

The preferential solvatation of human serum albumin (HSA) in dimethylsulfoxide (DMSO) aqueous solutions were studied using the densitometry method. It has been shown that at DMSO low concentrations HSA undergoes to preferential hydration, but at DMSO higher concentrations preferential binding of DMSO molecules to protein occurs. It has been estimated that DMSO exhibits stabilizing/destabilizing effect on HSA structure which is explained in terms of hydration/solvatation of protein, on the one hand, and the medium structure enhancement/disruption around the protein molecule, on the other hand.

Disulfide exchange in hydrogen-bonded cyclic assemblies: stereochemical self-selection by double dynamic chemistry.

PubMed

ten Cate, A Tessa; Dankers, Patricia Y W; Sijbesma, Rint P; Meijer, E W

2005-07-22

Stereoselective cyclization of cystine-based bifunctional 2-ureido-4[1H]-pyrimidinone derivatives in CDCl(3) solutions was demonstrated by (1)H NMR spectroscopy. Thiolate-catalyzed disulfide exchange in solution led to the equilibration of different diastereomers of 1. At low concentrations, where formation of cyclic assemblies is the dominant mode of association, the molecules act as their own template. At these concentrations the meso diastereomer is formed preferentially, indicating a higher stability of its cyclic assemblies under the applied conditions, in comparison to the other diastereomers.

Efficient Incorporation of Mg in Solution Grown GaN Crystals

NASA Astrophysics Data System (ADS)

Freitas, Jaime A., Jr.; Feigelson, Boris N.; Anderson, Travis J.

2013-11-01

Detailed spectrometry and optical spectroscopy studies carried out on GaN crystals grown in solution detect and identify Mg as the dominant shallow acceptor. Selective etching of crystals with higher Mg levels than that of the donor concentration background indicates that Mg acceptors incorporate preferentially in the N-polar face. Electrical transport measurements verified an efficient incorporation and activation of the Mg acceptors. These results suggest that this growth method has the potential to produce p-type doped epitaxial layers or p-type substrates characterized by high hole concentration and low defect density.

Treatment of high salinity brines by direct contact membrane distillation: Effect of membrane characteristics and salinity.

PubMed

Li, Jianfeng; Guan, Yunshan; Cheng, Fangqin; Liu, Yu

2015-12-01

Direct contact membrane distillation (DCMD) is one of the attractive technologies for high salinity brine treatment. In this study, four polytetrafluoroethylene (PTFE) membranes were examined in treating highly concentrated salt solutions. Results showed that non-supported membranes generally have a higher overall mass transfer coefficient but porosity seems to be the most important parameter controlling membrane flux and thermal efficiency. Supported membranes with large thickness had relatively higher thermal efficiency than small thickness. This can be attributed to their reduced heat loss through heat condition. In addition, KCl, NaCl and MgCl2 solutions showed distinct trends over flux decline at high salt concentrations (⩾2.0M). The difference in flux was largely due to the discrepancy in water activities of these solutions (KCl>NaCl>MgCl2). However, the effect of viscosity on permeate flux could not be neglected for MgCl2 at high salt concentrations as the suddenly increased viscosity could lead to serious temperature polarization. This study indicates that membrane distillation is a promising technology for high salinity brine treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Deswelling kinetics of polyacrylate gels in solutions of cetyltrimethylammonium bromide.

PubMed

Nilsson, Peter; Hansson, Per

2007-08-23

The deswelling kinetics of single sodium polyacrylate gel beads (radius 40-160 microm) in aqueous solutions of cetyltrimethylammonium bromide under conditions of forced convection are investigated using micromanipulator assisted light microscopy. The purpose of the study is to further evaluate a previously published model (J. Phys. Chem. B 2003, 107, 9203) using a higher homolog surfactant. For gels with expected fast deswelling (small gel size/low surfactant concentration) and/or in low electrolyte concentration, the model is found to correctly predict the deswelling characteristics of the gel beads. However, for some gels with expected slow deswelling, especially in high electrolyte concentration (10 mM NaBr), the model widely underestimates the required deswelling time. The reason for this is argued to be the longer time frame and high bromide concentration allowing the formation of a denser, more ordered structure in the surface phase, which resists the deformation and reorganization of material necessary for deswelling. Unexpectedly long lag times before the start of deswelling are also found for gels in low surfactant concentration, indicating that a relatively high surfactant concentration in the gel, greatly exceeding the critical aggregation concentration, is needed to start formation of a collapsed surface phase. This critical surfactant concentration is found to be dependent on initial gel radius, as small gels require a relatively higher concentration to initiate collapse.

Biocompatibility of new peritoneal dialysis solutions: clinical experience.

PubMed

Garcia-Lopez, E; Lindholm, B; Tranaeus, A

2000-01-01

The successful development of peritoneal dialysis (PD) during the last two decades has been made possible by using well-established glucose-based solutions with lactate as buffer. On the other hand, awareness has been increasing about the potentially negative effects of the high concentrations of glucose and lactate, and the low pH of conventional PD solutions. This awareness has prompted an intensive effort to search for and test alternative solutions. As a result, three new, more biocompatible solutions-containing either less glucose or less lactate--are available. Amino acid-based solution uses amino acids instead of glucose as the osmotic agent; it is indicated for treatment of malnutrition. The higher pH and absence of glucose in this solution may prevent alterations of the peritoneal membrane caused by acidity and high glucose concentrations. Bicarbonate/lactate-buffered solution contains a physiologic concentration of bicarbonate and a reduced concentration of lactate; it also has a physiologic pH and markedly reduced levels of glucose degradation products (GDPs). Icodextrin-based solution contains icodextrin as the osmotic agent; it is indicated for long dwells, delivering sustained ultrafiltration for more than 16 hours. This iso-osmolar glucose-free solution may reduce peritoneal membrane alterations caused by glucose or the hyperosmolality (or both) of conventional solutions. Clinical experience of the new solutions is now extensive, and their efficacy and safety are well documented. It therefore seems appropriate to state that we have entered a new era of PD therapy. Each of the new solutions may be less damaging to the peritoneal membrane than conventional solution. In addition, they permit better management of malnutrition and fluid status, and may thus help to improve PD patient survival. Although the effects of each of these new solutions have been well described, clinical documentation of the combined use of these new biocompatible PD solutions is still insufficient. However, the results of studies are expected, during the coming years, to support the combined use of the new solutions as the preferred standard practice for PD.

[Sodium chloride 0.9%: nephrotoxic crystalloid?].

PubMed

Dombre, Vincent; De Seigneux, Sophie; Schiffer, Eduardo

2016-02-03

Sodium chloride 0.9%, often incorrectly called physiological saline, contains higher concentration of chloride compared to plasma. It is known that the administration of sodium chloride 0.9% can cause hyperchloremic metabolic acidosis in a reproducible manner. The elevated chloride concentration in 0.9% NaCl solution can also adversely affect renal perfusion. This effect is thought to be induced by hyperchloremia that causes renal artery vasoconstriction. For these reasons, the use of 0.9% NaCl solution is raising attention and some would advocate the use of a more "physiological" solution, such as balanced solutions that contain a level of chloride closer to that of plasma. Few prospective, randomized, controlled trials are available today and most were done in a perioperative setting. Some studies suggest that the chloride excess in 0.9% NaCl solution could have clinical consequences; however, this remains to be established by quality randomized controlled trials.

Extraction and electrospinning of gelatin from fish skin.

PubMed

Songchotikunpan, Panida; Tattiyakul, Jirarat; Supaphol, Pitt

2008-04-01

Ultra-fine gelatin fibers were successfully fabricated by electrospinning from the solutions of Nile tilapia (Oreochromis niloticus) skin-extracted gelatin in either acetic acid or formic acid aqueous solutions. The extracted gelatin contained 7.3% moisture, 89.4% protein, 0.3% lipid, and 0.4% ash contents (on the basis of wet weight), while the bloom gel strength, the shear viscosity, and the pH values were 328 g, 17.8 mPa s, and 5.0, respectively. Both the acid concentration and the concentration of the gelatin solutions strongly influenced the properties of the as-prepared solutions and the obtained gelatin fibers. At low acid concentrations (i.e., 15% (w/v) extracted gelatin solutions in 10 and 20% (v/v) acetic acid solvents or 10-60% (v/v) formic acid solvents), a combination between smooth and beaded fibers was observed. At low concentrations of the gelatin solutions in either 40% (v/v) acetic acid solvent or 80% (v/v) formic acid solvent (i.e., 5-11%, w/v), either discrete beads or beaded fibers were obtained, while, at higher concentrations (i.e., 14-29%, w/v), only smooth or a combination of smooth and beaded fibers were obtained. The average diameters of the obtained fibers, regardless of the types of the acid solvents used, ranged between 109 and 761 nm. Lastly, cross-linking of the obtained gelatin fiber mats with glutaraldehyde vapor caused slight shrinkage from their original dimension, and the cross-linked gelatin fiber mats became stiffer.

Stability of urea in solution and pharmaceutical preparations.

PubMed

Panyachariwat, Nattakan; Steckel, Hartwig

2014-01-01

The stability of urea in solution and pharmaceutical preparations was analyzed as a function of temperature (25°-60°C), pH (3.11-9.67), and initial urea concentration (2.5%-20%). This study was undertaken to (i) obtain more extensive, quantitative information relative to the degradation of urea in both aqueous and non-aqueous solutions and in pharmaceutical preparations, and (ii) test the effects of initial urea concentration, pH, buffer, and temperature values on urea degradation. The stability analysis shows that urea is more stable at the pH range of 4-8 and the stability of urea decreases by increase in temperature for all pH values. Within the experimental range of temperature and initial urea concentration values, the lowest urea degradation was found with lactate buffer pH 6.0. The urea decomposition rate in solution and pharmaceutical preparations shows the dependence of the initial urea concentrations. At higher initial urea concentrations, the rate of degradation is a decreasing function with time. This suggests that the reverse reaction is a factor in the degradation of concentrated urea solution. For non-aqueous solvents, isopropanol showed the best effort in retarding the decomposition of urea. Since the losses in urea is directly influenced by its stability at a given temperature and pH, the stability analysis of urea by the proposed model can be used to prevent the loss and optimize the operating condition for urea-containing pharmaceutical preparations.

Bicarbonate is not the ultimate answer to the biocompatibility problems of CAPD solutions: a cytotoxicity test of CAPD solutions and effluents.

PubMed

Schambye, H T; Pedersen, F B; Wang, P

1992-01-01

Human polymorphonuclear granulocytes (PMN) were tested for migration and phagocytosis after exposure to CAPD solutions and effluents sampled during the first hour of dialysis from patients treated with lactate or bicarbonate based CAPD-solutions. The effluents from the lactate based solutions (Dianeal and Lockolys) reduced the migration and enhanced the phagocytosis compared to values obtained in a standard cell culture medium. Both cell functions increased during the dialysis period. In contrast, the cell-function only changed slightly when 87b, a bicarbonate based CAPD-solution (pH = 7.4, [HCO3-) = 29mM), was employed. During the first 30 minutes, the cells performed at a higher level when exposed to the 87b effluent than when exposed to the lactate effluents. The observations further indicated that optimal conditions for PMNs are at a bicarbonate concentration of less than 20 mM and a lactate concentration of less than 15mM. PMN migration is reduced by both lactate and bicarbonate based CAPD solutions and effluents collected during the first hour of dialysis. The bio-compatibility of CAPD solutions may be improved by combining the lactate and bicarbonate buffering systems in a solution with a concentration of less than 20 mM of bicarbonate and less than 15 mM of lactate.

Simultaneous removal of NO and SO2 using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS).

PubMed

Liu, Yangxian; Wang, Yan; Wang, Qian; Pan, Jianfeng; Zhang, Jun

2018-01-01

Simultaneous removal process of SO 2 and NO from flue gas using vacuum ultraviolet light (VUV)/heat/peroxymonosulfate (PMS) in a VUV spraying reactor was proposed. The key influencing factors, active species, reaction products and mechanism of SO 2 and NO simultaneous removal were investigated. The results show that vacuum ultraviolet light (185 nm) achieves the highest NO removal efficiency and yield of and under the same test conditions. NO removal is enhanced at higher PMS concentration, light intensity and oxygen concentration, and is inhibited at higher NO concentration, SO 2 concentration and solution pH. Solution temperature has a double impact on NO removal. CO 2 concentration has no obvious effect on NO removal. and produced from VUV-activation of PMS play a leading role in NO removal. O 3 and ·O produced from VUV-activation of O 2 also play an important role in NO removal. SO 2 achieves complete removal under all experimental conditions due to its very high solubility in water and good reactivity. The highest simultaneous removal efficiency of SO 2 and NO reaches 100% and 91.3%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

The influence of screening of the polyion electrostatic potential on the counterion dynamics in polyelectrolyte solutions

NASA Astrophysics Data System (ADS)

Schipper, F. J. M.; Hollander, J. G.; Leyte, J. C.

1998-10-01

The self-diffusion coefficient of tetra-methylammonium counterion in solutions of polymethacrylic acid in 0953-8984/10/41/004/img1 has been measured over a broad polyion concentration range at a constant degree of neutralization and at different ratios of added monovalent or bivalent salt to polyions. A maximum counterion self-diffusion coefficient was observed as a function of polyion concentration. The value of the self-diffusion coefficient at the maximum did not depend on the valency of the added salt. The maximum was found at lower polymer concentrations and with a higher value, when the ratio of added salt to polyions was increased, as predicted by the Poisson-Boltzmann-Smoluchowski equation in the cylindrical cell model for polyelectrolytes. At higher polyion concentrations a maximum counterion self-diffusion coefficient against the ratio of added salt and polyions was observed, which has not been reported before. Upon increasing this ratio the electrostatic potential of the polyelectrolyte gets screened, leading to an increase of the counterion self-diffusion coefficient. Concentration effects of the added salt on the other hand ultimately lead to a decrease of the counterion self-diffusion coefficient, which explains the occurrence of a maximum.

Electrothermal vaporization of mineral acid solutions in inductively coupled plasma mass spectrometry: comparison with sample nebulization

NASA Astrophysics Data System (ADS)

Mora, Juan; Gras, Luis; van Veen, Eric H.; de Loos-Vollebregt, Margaretha T. C.

1999-06-01

The analytical behaviour of an electrothermal vaporization (ETV) device for the introduction of mineral acid solutions in inductively coupled plasma mass spectrometry (ICP-MS) was evaluated. Water, nitric acid, hydrochloric acid, perchloric acid and sulphuric acid in concentrations within the 0.05-1.0 mol l-1 range were studied. For all the acids tested, increasing the acid concentration increases the ion signal and deteriorates the precision. The magnitude of the signal enhancement depends on the analyte and on the acid considered. Acid solutions give rise to ion signals that are between 2 and 10 times higher than those with water. Among the acids tested, sulphuric acid provides the highest signals. The addition of palladium reduces matrix effects due to the acids and increases the signal in ETV ICP-MS. In comparison with conventional sample nebulization (CS), the ETV sample introduction system provides higher sensitivities (between 2 and 20 times higher) at the same acid concentration. The magnitude of this improvement is similar to that obtained with a microwave desolvation system (MWDS). The ETV sample introduction system gives rise to the lowest background signals from matrix-induced species. Due to this fact, the limits of detection (LODs) obtained for the isotopes affected by any interference are lower for ETV sample introduction than those obtained with the CS and the MWDS. For the isotopes that do not suffer from matrix-induced spectral interferences, the ETV gives rise to LODs higher than those obtained with the CS. For these isotopes the lowest LODs are obtained with MWDS.

Stability Characterization of Quinazoline Derivative BG1188 by Optical Methods

NASA Astrophysics Data System (ADS)

Militaru, Andra; Smarandache, Adriana; Mahamoud, Abdallah; Damian, Victor; Ganea, Paul; Alibert, Sandrine; Pagès, Jean-Marie; Pascu, Mihail-Lucian

2011-08-01

3-[2-(dimethylamino)ethyl]-6-nitroquinazolin-4(3H)-one, labeled BG1188, is a new synthesized compound, out of a series of quinazoline derivatives developed to fight the multidrug resistance of antibiotics acquired by bacteria. A characterization of the BG1188 powder was made using FTIR spectra in order to evidence the functional groups in the medicine's molecule. The ultraviolet-visible (UV-Vis) absorption spectra were used to study the stability of the BG1188 solutions in two solvents and at different temperatures. BG1188 concentration in ultrapure water was varied between 2×10-3 M (stock solution) and 10-6 M. The concentration recommended by higher activity on bacteria was 10-3 M. For the same reason, this was the utilized concentration of BG1188 in dimethyl sulfoxide (DMSO). Time stability was characterized by comparing the time evolution of the UV-Vis absorption spectra of the BG1188 solutions in ultrapure de-ionized water or in DMSO. The spectra were recorded daily for about 4 months after the preparation for the BG1188 solutions in ultrapure water. Generally, samples are stable within the experimental errors at concentrations higher than 10-5 M, but the stability time interval may vary from 119 days at 10-4 M to 34 days at 10-5 M. Time evolution of the absorption spectra at 10-3 M in ultrapure water shows reproducibility within the measuring errors (±1.045%) for time intervals up to 1032 hours (more than 40 days) after preparation. On the other hand, BG1188 solutions in DMSO may be considered unstable because the absorption spectra modify in terms of peak shapes and intensities, indicating that the samples exhibit modifications immediately after preparation. Regardless the solvent used, some aggregation phenomena took place and wire-like aggregates were observed in all the solutions with the naked eye. These aggregates were analyzed, tentatively, using optical microscopy and FTIR.

Kinetics of mercuric chloride retention by soils

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

Amacher, M.C.; Selim, H.M.; Iskandar, I.K.

A nonlinear multireaction model was used to describe kinetic data for HgCl{sub 2} retention by five soils. A three-parameter version of the model consisting of a reversible nonlinear (nth order, n < 1) reaction and an irreversible first-order reaction was capable of describing HgCl{sub 2} retention data for Cecil (clayey, kaolinitic, thermic Typic Kanhapludult) and Windsor (mixed, mesic Typic Udipsamment) soils at all initial solution Hg concentrations, and data for Norwood, (fine-silty, mixed (calcareous), thermic, Typic Udifluvent), Olivier (fine-silty, mixed, thermic Aquic Fragiudalt), and Sharkey (very-fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soils at initial solution Hg concentrations below 5 mg/L.more » A five-parameter version of the model, with an added reversible nonlinear reaction, provided a more accurate description of the retention data for the Norwood, Olivier, and Sharkey soils at initial solution Hg concentrations above 5 mg/L. The second reaction needed to describe the data at higher Hg concentrations suggests the presence of a second type of sorption sites, or a precipitation or coprecipitation reaction not encountered at lower Hg concentrations. Release of Hg from the soils was induced by serial dilution of the soil solution, but not all the soil Hg was reversibly retained. This was also indicated by the model. Release of soil Hg depended on the concentration of retained Hg with significant Hg release occurring only at high concentrations of retained Hg. A multireaction model is needed to describe Hg retention in soils because of the many solid phases that can remove Hg from solution.« less

Rapid tissue dissolution efficiency of electrically-activated sodium hypochlorite on bovine muscle.

PubMed

Ertugrul, Ihsan Furkan; Maden, Murat; Orhan, Ekim Onur; Ozkorucuklu, Sabriye Percin; Aglarca, Ali Vasfi

2014-10-01

Sodium hypochlorite (NaOCl) is a common antimicrobial and tissue-dissolving irrigant. The aim of this in vitro study is to evaluate and compare dissolution capacities of sodium hypochlorite solutions after electrically activation (E-NaOCl) on bovine muscle specimens at various time periods and concentrations. Three sodium hypochlorite solutions of 1.25%, 2.5%, and 5% were tested at 3-min. and 5-min. with and without activation by electrically. Distilled water and NaOCl solutions without electrically activation were used as controls. Pieces of bovine muscle tissue (34 ± 2 mg) were placed in 10 mL of each solution at room temperature. In the group of E-NaOCl, electrically activation was performed through the potentiostat. The tissue specimens were weighed before and after treatment, and the percentage of weight loss was calculated. Weight loss of the tissue increased with the concentration of E-NaOCl and NaOCl. Higher concentration and electrically activation considerably enhanced the efficacy of sodium hypochlorite. The effect of electrically activation on tissue dissolution was much greater than that of same concentrations in the groups of NaOCl (P < 0.001). Tissue weight loss was significantly higher in 2.5% and 5% E-NaOCl at 3 min. than in 2.5% and 5% NaOCl at 5 min. (P < 0.05). There were not any significant differences between the 2.5% E-NaOCl and 5% NaOCl at 5 min. (P > 0.05). Electrically activation can improve the tissue-dissolving effectiveness of sodium hypochlorite.

Enzyme stabilization by glass-derived silicates in glass-exposed aqueous solutions

USGS Publications Warehouse

Ives, J.A.; Moffett, J.R.; Arun, P.; Lam, D.; Todorov, T.I.; Brothers, A.B.; Anick, D.J.; Centeno, J.; Namboodiri, M.A.A.; Jonas, W.B.

2010-01-01

Objectives: To analyze the solutes leaching from glass containers into aqueous solutions, and to show that these solutes have enzyme activity stabilizing effects in very dilute solutions. Methods: Enzyme assays with acetylcholine esterase were used to analyze serially succussed and diluted (SSD) solutions prepared in glass and plastic containers. Aqueous SSD preparations starting with various solutes, or water alone, were prepared under several conditions, and tested for their solute content and their ability to affect enzyme stability in dilute solution. Results: We confirm that water acts to dissolve constituents from glass vials, and show that the solutes derived from the glass have effects on enzymes in the resultant solutions. Enzyme assays demonstrated that enzyme stability in purified and deionized water was enhanced in SSD solutions that were prepared in glass containers, but not those prepared in plastic. The increased enzyme stability could be mimicked in a dose-dependent manner by the addition of silicates to the purified, deionized water that enzymes were dissolved in. Elemental analyses of SSD water preparations made in glass vials showed that boron, silicon, and sodium were present at micromolar concentrations. Conclusions: These results show that silicates and other solutes are present at micromolar levels in all glass-exposed solutions, whether pharmaceutical or homeopathic in nature. Even though silicates are known to have biological activity at higher concentrations, the silicate concentrations we measured in homeopathic preparations were too low to account for any purported in vivo efficacy, but could potentially influence in vitro biological assays reporting homeopathic effects. ?? 2009 The Faculty of Homeopathy.

Plasma Electrolytic Oxidation Coatings on Pure Ti Substrate: Effects of Na3PO4 Concentration on Morphology and Corrosion Behavior of Coatings in Ringer's Physiological Solution

NASA Astrophysics Data System (ADS)

Roknian, Masoud; Fattah-alhosseini, Arash; Gashti, Seyed Omid

2018-03-01

Plasma electrolytic oxidation has been used as a relatively new method for applying ceramic coatings having different features. In the present study, commercially pure titanium is used as substrate, and effects of trisodium phosphate electrolyte concentration on the microstructure, as well as corrosion behavior of the coating in Ringer's physiological solution are investigated. The morphology and phase compositions of coatings were analyzed by using scanning electron microscopy (SEM) and x-ray diffraction patterns. The study on the corrosion behavior of samples in a Ringer's physiological solution was carried out using open-circuit potential potentiodynamic polarization and electrochemical impedance spectroscopy. The results of electrochemical analysis proved that higher concentration of phosphate electrolyte leads to increase in the corrosion resistance of applied coatings. Accordingly, obtained results revealed that the optimum electrolyte concentration for the best corrosion behavior was 20 g L-1. Furthermore, SEM images and reduction in the dielectric breakdown potential indicated that increase in the electrolyte concentration leads to morphological improvement and smoothening of the surface.

Urea enhances the photodynamic efficiency of methylene blue.

PubMed

Nuñez, Silvia C; Yoshimura, Tania M; Ribeiro, Martha S; Junqueira, Helena C; Maciel, Cleiton; Coutinho-Neto, Maurício D; Baptista, Maurício S

2015-09-01

Methylene blue (MB) is a well-known photosensitizer used mostly for antimicrobial photodynamic therapy (APDT). MB tends to aggregate, interfering negatively with its singlet oxygen generation, because MB aggregates lean towards electron transfer reactions, instead of energy transfer with oxygen. In order to avoid MB aggregation we tested the effect of urea, which destabilizes solute-solute interactions. The antimicrobial efficiency of MB (30 μM) either in water or in 2M aqueous urea solution was tested against a fungus (Candida albicans). Samples were kept in the dark and irradiation was performed with a light emitting diode (λ = 645 nm). Without urea, 9 min of irradiation was needed to achieve complete microbial eradication. In urea solution, complete eradication was obtained with 6 min illumination (light energy of 14.4 J). The higher efficiency of MB/urea solution was correlated with a smaller concentration of dimers, even in the presence of the microorganisms. Monomer to dimer concentration ratios were extracted from the absorption spectra of MB solutions measured as a function of MB concentration at different temperatures and at different concentrations of sodium chloride and urea. Dimerization equilibrium decreased by 3 and 6 times in 1 and 2M urea, respectively, and increased by a factor of 6 in 1M sodium chloride. The destabilization of aggregates by urea seems to be applied to other photosensitizers, since urea also destabilized aggregation of Meso-tetra(4-n-methyl-pyridyl)porphyrin, which is a positively charged porphyrin. We showed that urea destabilizes MB aggregates mainly by causing a decrease in the enthalpic gain of dimerization, which was exactly the opposite of the effect of sodium chloride. In order to understand this phenomenon at the molecular level, we computed the free energy for the dimer association process (ΔG(dimer)) in aqueous solution as well as its enthalpic component in aqueous and in aqueous/urea solutions by molecular dynamics simulations. In 2M-urea solution the atomistic picture revealed a preferential solvation of MB by urea compared with MB dimers while changes in ΔH(dimer) values demonstrated a clear shift favoring MB monomers. Therefore, MB monomers are more stable in urea solutions, which have significantly better photophysics and higher antimicrobial activity. This information can be of use for dental and medical professionals that are using MB based APDT protocols. Copyright © 2015 Elsevier B.V. All rights reserved.

Spatial and temporal geochemical trends in the hydrothermal system of Yellowstone National Park: Inferences from river solute fluxes

USGS Publications Warehouse

Hurwitz, S.; Lowenstern, J. B.; Heasler, H.

2007-01-01

We present and analyze a chemical dataset that includes the concentrations and fluxes of HCO3-, SO42-, Cl-, and F- in the major rivers draining Yellowstone National Park (YNP) for the 2002-2004 water years (1 October 2001 - 30 September 2004). The total (molar) flux in all rivers decreases in the following order, HCO3- > Cl- > SO42- > F-, but each river is characterized by a distinct chemical composition, implying large-scale spatial heterogeneity in the inputs of the various solutes. The data also display non-uniform temporal trends; whereas solute concentrations and fluxes are nearly constant during base-flow conditions, concentrations decrease, solute fluxes increase, and HCO3-/Cl-, and SO42-/Cl- increase during the late-spring high-flow period. HCO3-/SO42- decreases with increasing discharge in the Madison and Falls Rivers, but increases with discharge in the Yellowstone and Snake Rivers. The non-linear relations between solute concentrations and river discharge and the change in anion ratios associated with spring runoff are explained by mixing between two components: (1) a component that is discharged during base-flow conditions and (2) a component associated with snow-melt runoff characterized by higher HCO3-/Cl- and SO42-/Cl-. The fraction of the second component is greater in the Yellowstone and Snake Rivers, which host lakes in their drainage basins and where a large fraction of the solute flux follows thaw of ice cover in the spring months. Although the total river HCO3- flux is larger than the flux of other solutes (HCO3-/Cl- ??? 3), the CO2 equivalent flux is only ??? 1% of the estimated emission of magmatic CO2 soil emissions from Yellowstone. No anomalous solute flux in response to perturbations in the hydrothermal system was observed, possibly because gage locations are too distant from areas of disturbance, or because of the relatively low sampling frequency. In order to detect changes in river hydrothermal solute fluxes, sampling at higher frequencies with better spatial coverage would be required. Our analysis also suggests that it might be more feasible to detect large-scale heating or cooling of the hydrothermal system by tracking changes in gas and steam flux than by tracking changes in river solute flux.

Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration

NASA Astrophysics Data System (ADS)

Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A.; Kotha, Shiva P.

2013-02-01

PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr33423f

Intravenous infusion of amino acids in dogs attenuates hypothermia during anaesthesia and stimulates insulin secretion.

PubMed

Takashima, Satoshi; Shibata, Sanae; Yamada, Kazuto; Ogawa, Mizuho; Nishii, Naohito; Kitagawa, Hitoshi

2016-07-01

To evaluate the effect of intravenous infusion of amino acids on the prevention of hypothermia during anaesthesia in dogs. Randomized experimental trial. Seven healthy Beagle dogs. Four concentrations of amino acids were prepared with a 10% amino acid solution and an acetated Ringer's solution, and dogs were infused with each of the solutions at 1 week intervals. Dogs were infused with amino acid solution at 12 mL kg(-1)  hour(-1) for 60 minutes before and for 60 minutes after induction of anaesthesia. Acetated Ringer's solution was infused at the same rate for the remaining 60 minutes of anaesthesia. The infusion treatments were: 1) A0, nutrient-free acetated Ringer's solution; 2) A6, 0.6 g kg(-1)  hour(-1) ; 3) A9, 0.9 g kg(-1)  hour(-1) ; and 4) A12, 1.2 g kg(-1) hour(-1) . Rectal temperature (RT), heart rate (HR), mean arterial pressure (MAP), blood insulin, glucose, urea nitrogen (BUN) and creatinine concentrations, and time to extubation were measured. Before anaesthesia, RT was not affected by amino acid infusion. RT decreased progressively during anaesthesia and the absolute values of RT from 30 to 120 minutes were significantly higher in A12 than in A0 (p < 0.05). Reductions in HR and MAP during anaesthesia were attenuated by amino acid infusion in a dose-dependent manner. Plasma insulin concentration was significantly higher in A12 than in A0 during amino acid infusion and the increase in insulin concentration was greater during than before anaesthesia. BUN increased during amino acid infusion in a dose- and time-dependent fashion. Time until extubation was shorter in A12 than in A0. Amino acids infused at 1.2 g kg(-1)  hour(-1) in dogs attenuated the decrease in RT, HR, and MAP during anaesthesia, and induced a significant increase in plasma insulin concentration. © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

Green synthesis of highly concentrated aqueous colloidal solutions of large starch-stabilised silver nanoplatelets.

PubMed

Cheng, Fei; Betts, Jonathan W; Kelly, Stephen M; Hector, Andrew L

2015-01-01

A simple, environmentally friendly and cost-effective method has been developed to prepare a range of aqueous silver colloidal solutions, using ascorbic acid as a reducing agent, water-soluble starch as a combined crystallising, stabilising and solubilising agent, and water as the solvent. The diameter of silver nanoplatelets increases with higher concentrations of AgNO3 and starch. The silver nanoparticles are also more uniform in shape the greater the diameter of the nanoparticles. Colloidal solutions with a very high concentration of large, flat, hexagonal silver nanoplatelets (~230 nm in breadth) have been used to deposit and fix an antibacterial coating of these large starch-stabilised silver nanoplates on commercial cotton fibres, using a simple dip-coating process using water as the solvent, in order to study the dependence of the antibacterial properties of these nanoplatelets on their size. Copyright © 2014 Elsevier B.V. All rights reserved.

Production of nattokinase by high cell density fed-batch culture of Bacillus subtilis.

PubMed

Kwon, Eun-Yeong; Kim, Kyung Mi; Kim, Mi Kyoung; Lee, In Young; Kim, Beom Soo

2011-09-01

Bacillus subtilis was cultivated to high cell density for nattokinase production by pH-stat fed-batch culture. A concentrated mixture solution of glucose and peptone was automatically added by acid-supplying pump when culture pH rose above high limit. Effect of the ratio of glucose to peptone in feeding solution was investigated on cell growth and nattokinase production by changing the ratio from 0.2 to 5 g glucose/g peptone. The highest cell concentration was 77 g/L when the ratio was 0.2 g glucose/g peptone. Cell concentration decreased with increasing the ratio of glucose to peptone in feeding solution, while the optimum condition existed for nattokinase production. The highest nattokinase activity was 14,500 unit/mL at a ratio of 0.33 g glucose/g peptone, which was 4.3 times higher than that in batch culture.

Influence of the current density on the electrochemical treatment of concentrated 1-butyl-3-methylimidazolium chloride solutions on diamond electrodes.

PubMed

Marcionilio, Suzana M L de Oliveira; Alves, Gisele M; E Silva, Rachel B Góes; Marques, Pablo J Lima; Maia, Poliana D; Neto, Brenno A D; Linares, José J

2016-10-01

This paper focuses on the influence of the current density treatment of a concentrated 1-butyl-3-methylimidazolium chloride (BMImCl) solution on an electrochemical reactor with a boron-doped diamond (BDD) anode. The decrease in the total organic carbon (TOC) and the BMImCl concentration demonstrate the capability of BDD in oxidizing ionic liquids (ILs) and further mineralizing (to CO2 and NO3 (-)) more rapidly at higher current densities in spite of the reduced current efficiency of the process. Moreover, the presence of Cl(-) led to the formation of oxychlorinated anions (mostly ClO3 (-) and ClO4 (-)) and, in combination with the ammonia generated in the cathode from the nitrate reduction, chloramines, more intensely at higher current density. Finally, the analysis of the intermediates formed revealed no apparent influence of the current density on the BMImCl degradation mechanism. The current density presents therefore a complex influence on the IL treatment process that is discussed throughout this paper.

Influence of the extraction process on the rheological and structural properties of agars.

PubMed

Sousa, Ana M M; Borges, João; Silva, A Fernando; Gonçalves, Maria P

2013-07-01

Agars obtained by traditional hot-water (TWE) and microwave-assisted (MAE) extractions were compared in terms of their rheological and physicochemical properties and molecular self-association in solutions of low (0.05%, w/w) and high (1.5%, w/w) polymer concentrations. At low concentration, thin gelled layers were imaged by AFM. Slow or rapid cooling of the solutions influenced structure formation. In each case, TWE and MAE agar structures were different and apparently larger for MAE. At high concentration, progressive structural reinforcement was seen; while TWE agar showed a more open and irregular 3D network, MAE agar gel imaged by cryoSEM was denser and fairly uniform. The rheological (higher thermal stability and consistency) and mechanical (higher gel strength) behaviors of MAE agar seemed consistent with a positive effect of molecular mass and 3,6-anhydro-α-l-galactose content. MAE produced non-degraded agar comparable with commercial ones and if properly monitored, could be a promising alternative to TWE. Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface acetylation of bamboo cellulose: preparation and rheological properties.

PubMed

Cai, Jie; Fei, Peng; Xiong, Zhouyi; Shi, Yongjun; Yan, Kai; Xiong, Hanguo

2013-01-30

In this study, purified bamboo cellulose was used to synthesize cellulose diacetate (B-CDA). The synthesis was controlled by determination of the degree of substitution and insoluble residue content. The product then was characterized by FTIR. The rheological properties of B-CDA solutions in acetone/N,N-dimethylacetamide (DMAc) solvent system were systematically investigated on an advanced rheometer, including the dependence of apparent viscosity η(α), non-Newtonian index n, and structural viscosity index Δη on the concentration and temperature of the solutions. B-CDA-acetone/DMAc solution is a shear-thinning fluid. With increasing solution concentration and decreasing temperature, Δη increased, whereas n decreased, which indicates a deteriorating spinnability. Moreover, the values of the viscous flow activation energy E(η) based on the Arrhenius equation increased when the shear rate γ was enhanced, which indicates that the η(α) of the solution is more sensitive to temperature in the higher γ values. The results are favorable for predicting the B-CDA solution spinnability. Copyright © 2012 Elsevier Ltd. All rights reserved.

Contribution of extracellular ice formation and the solution effects to the freezing injury of PC-3 cells suspended in NaCl solutions.

PubMed

Takamatsu, Hiroshi; Zawlodzka, Sylwia

2006-08-01

The mechanism of cell injury during slow freezing was examined using PC-3 human prostate adenocarcinoma cells suspended in NaCl solutions. The objective was to evaluate contribution of extracellular ice and the 'solution effects' to freezing injury separately. The solution effects that designate the influence of elevated concentration were evaluated from a pseudo-freezing experiment, where cells were subjected to the milieu that simulated a freeze-thaw process by changing the NaCl concentration and the temperature at the same time. The effect of extracellular ice formation on cell injury was then estimated from the difference in cell survival between the pseudo-freezing experiment and a corresponding freezing experiment. When cells were frozen to a relatively higher freezing temperature at -10 degrees C, about 30% of cells were damaged mostly due to extracellular ice formation, because the concentration increase without ice formation to 2.5-M NaCl, i.e., the equilibrium concentration at -10 degrees C, had no effect on cell survival. In contrast, in the case of the lower freezing temperature at -20 degrees C, about 90% of cells were injured by both effects, particularly 60-80% by the solution effects among them. The present results suggested that the solution effects become more crucial to cell damage during slow freezing at lower temperatures, while the effect of ice is limited to some extent.

Free Active Chlorine in Sodium Hypochlorite Solutions Admixed with Octenidine, SmearOFF, Chlorhexidine, and EDTA.

PubMed

Krishnan, Unni; Saji, Sreeja; Clarkson, Roger; Lalloo, Ratilal; Moule, Alex J

2017-08-01

The therapeutic effects of sodium hypochlorite (NaOCl) solutions are dependent on the levels of free available chlorine (FAC). Mixing these solutions with irrigants can result in significant reductions in FAC. Although the effect of some irrigants on FAC is known, the effect of other commonly used irrigants is not. Thus, the therapeutic ramifications of the concurrent use of these on the efficiency of NaOCl solutions is not known. Aliquots of 5.2% (w/v) NaOCl solutions were admixed in proportions of 90:10, 80:20, and 50:50 with the following irrigants: octenidine dihydrochloride (OCT); SmearOFF (Vista Dental Products, Racine, WI), 17% EDTA; and 0.2%, 2%, and 5% chlorhexidine (CHX) solutions. Changes in FAC were measured by iodometric titration. Statistical differences between means were determined using a post hoc Tukey analysis test after an analysis of variance. OCT appeared not to affect FAC and was significantly different than all other irrigants, except for 90:10 and 80:20 mixtures of low concentration (0.2%) CHX. CHX solutions showed a marked concentration- and mixture proportion-dependent detrimental effect on FAC. The reduction of FAC between different concentrations of CHX was statistically significant in 80:20 and 50:50 proportions, with 50:50 mixtures of 5% CHX having the greatest influence. Mixtures containing even small proportions of SmearOFF or EDTA exhibited significant losses in FAC. OCT has little effect on FAC and can be used concurrently with NaOCl solutions. Higher concentrations of CHX significantly affect FAC. Their combined use with NaOCl solutions should be avoided. EDTA and SmearOFF should not be mixed with NaOCl solutions. Copyright © 2017 American Association of Endodontists. All rights reserved.

Characterization of the oligomeric states of insulin in self-assembly and amyloid fibril formation by mass spectrometry.

PubMed Central

Nettleton, E J; Tito, P; Sunde, M; Bouchard, M; Dobson, C M; Robinson, C V

2000-01-01

The self-assembly and aggregation of insulin molecules has been investigated by means of nanoflow electrospray mass spectrometry. Hexamers of insulin containing predominantly two, but up to four, Zn(2+) ions were observed in the gas phase when solutions at pH 4.0 were examined. At pH 3.3, in the absence of Zn(2+), dimers and tetramers are observed. Spectra obtained from solutions of insulin at millimolar concentrations at pH 2.0, conditions under which insulin is known to aggregate in solution, showed signals from a range of higher oligomers. Clusters containing up to 12 molecules could be detected in the gas phase. Hydrogen exchange measurements show that in solution these higher oligomers are in rapid equilibrium with monomeric insulin. At elevated temperatures, under conditions where insulin rapidly forms amyloid fibrils, the concentration of soluble higher oligomers was found to decrease with time yielding insoluble high molecular weight aggregates and then fibrils. The fibrils formed were examined by electron microscopy and the results show that the amorphous aggregates formed initially are converted to twisted, unbranched fibrils containing several protofilaments. Fourier transform infrared spectroscopy shows that both the soluble form of insulin and the initial aggregates are predominantly helical, but that formation of beta-sheet structure occurs simultaneously with the appearance of well-defined fibrils. PMID:10920035

Blow-Out Velocities of Solutions of Hydrocarbons and Boron Hydride - Hydrocarbon Reaction Products in a 1 7/8-Inch-Diameter Combustor

NASA Technical Reports Server (NTRS)

Morris, James F.; Lord, Albert M.

1957-01-01

Blow-out velocities were determined for JP-4 solutions containing: (1) 10 % ethylene - decaborane reaction product, (2) 10% and 20% acetylene - diborane reaction product, and (3) 5.5%, 15.7%, and 30.7% methylacetylene - diborane reaction product. These were compared with blow-out velocities for JP-4, propylene oxide, and neohexane and previously reported data for JP-4 solutions of pentaborane. For those reaction products investigated, the blow-out velocities at a fixed equivalence ratio were higher for those materials containing higher boron concentrations; that is, blow-out velocity increased in the following order: (1) methylacetylene - diborane, (2) acetylene - diborane, and (3) ethylene - decaborane reaction products.

Intrapleural polymeric films containing cisplatin for malignant pleural mesothelioma in a rat tumour model: a preliminary study.

PubMed

Ampollini, Luca; Sonvico, Fabio; Barocelli, Elisabetta; Cavazzoni, Andrea; Bilancia, Rocco; Mucchino, Claudio; Cantoni, Anna Maria; Carbognani, Paolo

2010-03-01

This study aims to investigate the effect of intrapleural polymeric films containing cisplatin on the local recurrence of malignant pleural mesothelioma in a rat tumour model. An orthotopic rat recurrence model of malignant pleural mesothelioma was used. Five animals per group were evaluated. Polymeric films (4.5 cm diameter) for the local delivery of anticancer drug were constructed: hyaluronate, chitosan and the combined dual-layer polymers were loaded with cisplatin at a concentration of 100 mgm(-2). Animals without any adjuvant therapy were used as control. Mesothelioma cells were injected subpleurally in the anaesthetised rats. Six days later, a pleural tumour of 5.5mm was resected and a left pneumonectomy and pleural abrasion were performed. Thereafter, the cisplatin-loaded and unloaded films or cisplatin solution were intrapleurally applied, according to randomisation. After 6 days, animals were euthanised and organs harvested for morphological and histological evaluations. The primary endpoint was the volume of tumour recurrence. The secondary endpoints were treatment-related toxicity; cisplatin serum concentration evaluated at different time points; and cisplatin concentration in the pleura measured at autopsy. Analysis of variance (ANOVA) was used for statistical analysis. Bonferroni correction was applied for comparison between all groups. Tumour volume was significantly reduced in the hyaluronate cisplatin and hyaluronate-chitosan cisplatin groups in comparison to control groups (p=0.001 and p<0.0001, respectively). Animals treated with hyaluronate-chitosan cisplatin had a tumour recurrence significantly lesser than animals treated with cisplatin solution (p=0.003) and hyaluronate cisplatin (p=0.032). No toxicity related to the different treatments was observed. On postoperative days 1 and 2, cisplatin was detected in the serum at a concentration six- and sevenfold significantly higher in the hyaluronate cisplatin and hyaluronate-chitosan cisplatin groups, in comparison to cisplatin solution, and was maintained over time. Cisplatin levels in the pleura were higher in the hyaluronate-chitosan cisplatin group than in all others. Hyaluronate-chitosan cisplatin was significantly effective in reducing tumour recurrence compared with cisplatin solution. Hyaluronate and hyaluronate-chitosan loaded with cisplatin assured significantly higher and more prolonged plasmatic drug concentrations than cisplatin solution without increasing toxicity. Copyright (c) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

Code of Federal Regulations, 2012 CFR

2012-01-01

.... Acceptable disinfection procedures include individual or combination treatments with: Solutions having a pH of 12 or higher or 3 or lower with a contact time of at least 10 minutes; heat at or above 56 °C for at least 15 minutes; chlorine solutions having a concentration of at least 500 ppm with a contact...

9 CFR 93.904 - Health certificate for live fish, fertilized eggs, and gametes.

Code of Federal Regulations, 2013 CFR

2013-01-01

.... Acceptable disinfection procedures include individual or combination treatments with: Solutions having a pH of 12 or higher or 3 or lower with a contact time of at least 10 minutes; heat at or above 56 °C for at least 15 minutes; chlorine solutions having a concentration of at least 500 ppm with a contact...

Factors affecting the viscosity in high concentration solutions of different monoclonal antibodies.

PubMed

Yadav, Sandeep; Shire, Steven J; Kalonia, Devendra S

2010-12-01

The viscosity profiles of four different IgG(1) molecules were studied as a function of concentration at pH 6.0. At high concentrations, MAb-H and -A showed significantly higher viscosities as compared to MAb-G and -E. Zeta Potential (ξ) measurements showed that all the IgG(1) molecules carried a net positive charge at this pH. MAb-G showed the highest positive zeta potential followed by MAb-E, -H, and -A. A consistent interpretation of the impact of net charge on viscosity for these MAbs is not possible, suggesting that electroviscous effects cannot explain the differences in viscosity. Values of k(D) (dynamic light scattering) indicated that the intermolecular interactions were repulsive for MAb-E and -G; and attractive for MAb-H and -A. Solution storage modulus (G') in high concentration solutions was consistent with attractive intermolecular interactions for MAb-H and -A, and repulsive interactions for MAb-G and -E. Effect of salt addition on solution G' and k(D) indicated that the interactions were primarily electrostatic in nature. The concentration dependent viscosity data were analyzed using a modified Ross and Minton equation. The analysis explicitly differentiates between the effect of molecular shape, size, self-crowding, and electrostatic intermolecular interactions in governing high concentration viscosity behavior. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Determining equilibrium osmolarity in poly(ethylene glycol)/chondrotin sulfate gels mimicking articular cartilage.

PubMed

Sircar, S; Aisenbrey, E; Bryant, S J; Bortz, D M

2015-01-07

We present an experimentally guided, multi-phase, multi-species polyelectrolyte gel model to make qualitative predictions on the equilibrium electro-chemical properties of articular cartilage. The mixture theory consists of two different types of polymers: poly(ethylene gylcol) (PEG), chondrotin sulfate (ChS), water (acting as solvent) and several different ions: H(+), Na(+), Cl(-). The polymer chains have covalent cross-links whose effect on the swelling kinetics is modeled via Doi rubber elasticity theory. Numerical studies on equilibrium polymer volume fraction and net osmolarity (difference in the solute concentration across the gel) show a complex interplay between ionic bath concentrations, pH, cross-link fraction and the average charge per monomer. Generally speaking, swelling is aided due to a higher average charge per monomer (or a higher particle fraction of ChS, the charged component of the polymer), low solute concentration in the bath, a high pH or a low cross-link fraction. A peculiar case arises at higher values of cross-link fraction, where it is observed that increasing the average charge per monomer leads to gel deswelling. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.

PubMed

Zampella, Mariavittoria; Adamo, Paola

2010-01-01

A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability.

Effect of molecular weight of polystyrensulfonic acid sodium salt polymers on the precipitation kinetics of sodium bicarbonate

NASA Astrophysics Data System (ADS)

Martínez-Cruz, Nancy; Carrillo-Romo, Felipe; Jaramillo-Vigueras, David

2004-10-01

This paper analyzes the effect of polystyrensulfonic acid sodium salt (NaPSS), obtained by kinetic precipitation from solutions of polymers of molecular weight 245 000 and 38 000 g mol-1 in sodium bicarbonate (NaHCO3) itself precipitated from synthetic brine. Crystal size, shape and the additive adsorbed are reported. X shaped and hexagonal prisms crystals with different aspect ratios were obtained. The results show that with increasing polymer concentration the crystal size decreases, from 0.27 to 0.48 mm. Additionally, the higher molecular weight polymer shows both higher adsorption capacity and higher crystal habit modification. Crystal shape patterns were similar for both polymers; however, the higher molecular weight material induced changes at lower concentration. It was observed that the precipitation rate reached a minimum with increasing additive concentration.

Phytoextraction of Cadmium and Zinc By Sedum plumbizincicola Using Different Nitrogen Fertilizers, a Nitrification Inhibitor and a Urease Inhibitor.

PubMed

Arnamwong, Suteera; Wu, Longhua; Hu, Pengjie; Yuan, Cheng; Thiravetyan, Paitip; Luo, Yongming; Christie, Peter

2015-01-01

Cadmium (Cd) and zinc (Zn) phytoavailability and their phytoextraction by Sedum plumbizincicola using different nitrogen fertilizers, nitrification inhibitor (dicyandiamide, DCD) and urease inhibitor (N-(n-Butyl) thiophosphoric triamide, NBPT) were investigated in pot experiments where the soil was contaminated with 0.99 mg kg(-1) of Cd and 241 mg kg(-1) Zn. The soil solution pH varied between 7.30 and 8.25 during plant growth which was little affected by the type of N fertilizer. The (NH4)2SO4+DCD treatment produced higher NH4+-N concentrations in soil solution than the (NH4)2SO4 and NaNO3 treatment which indicated that DCD addition inhibited the nitrification process. Shoot Cd and Zn concentrations across all treatments showed ranges of 52.9-88.3 and 2691-4276 mg kg(-1), respectively. The (NH4)2SO4+DCD treatment produced slightly higher but not significant Cd and Zn concentrations in the xylem sap than the NaNO3 treatment. Plant shoots grown with NaNO3 had higher Cd concentrations than (NH4)2SO4+DCD treatment at 24.0 and 15.4 mg kg(-1), respectively. N fertilizer application had no significant effect on shoot dry biomass. Total Cd uptake in the urea+DCD treatment was higher than in the control, urea+NBPT, urea+NBPT+DCD, or urea treatments, by about 17.5, 23.3, 10.7, and 25.1%, respectively.

Freeze-drying of tert-butyl alcohol/water cosolvent systems: effects of formulation and process variables on residual solvents.

PubMed

Wittaya-Areekul, S; Nail, S L

1998-04-01

The objective of this study was to identify significant formulation and processing variables affecting levels of tert-butyl alcohol (TBA) and isopropyl alcohol (IPA) in freeze-dried solids prepared from TBA/water cosolvent systems. The variables examined were the physical state of the solute (crystalline vs amorphous), initial TBA concentration, freezing rate, cake thickness, and the temperature and duration of secondary drying. Sucrose and glycine were used as models for noncrystallizing and crystallizing solutes, respectively. The TBA concentration above which eutectic crystallization takes place was determined by differential scanning calorimetry. Model formulations were subjected to extremes of freezing rate by either dipping in liquid nitrogen or by slowly freezing on the shelf of a freeze-dryer. Dynamics of solvent loss during secondary drying was determined by withdrawing samples as a function of time at different shelf temperatures using a thief system. On the basis of these studies, the most important determinant of residual TBA level is the physical state of the solute. Freeze-dried glycine contained very low levels of residual TBA (0.01-0.03%) regardless of freezing rate or initial TBA concentration. For freeze-dried sucrose, residual TBA levels were approximately 2 orders of magnitude higher and were significantly affected by initial TBA concentration and freezing rate. For the sucrose/TBA/water system, relatively low residual TBA levels were obtained when the initial TBA level was above the threshold concentration for eutectic crystallization of TBA, whereas samples freeze-dried from solutions containing TBA concentrations below this threshold contained significantly higher levels of TBA. Residual IPA levels increased continuously with initial concentration of TBA in the sucrose/TBA/water system. Formulations of sucrose/TBA/water which were frozen rapidly contained residual TBA levels which were approximately twice those measured in the same formulation after slow freezing and drying under the same conditions. For the sucrose/TBA/water system, the temperature and time of secondary drying had only minimal influence on residual TBA in the freeze-dried solid. At low initial TBA concentrations (2%), residual TBA increases with increased cake thickness, perhaps because of the influence of depth of fill on effective freezing rate.

Solubility Limits of Dibutyl Phosphoric Acid in Uranium Solutions at SRS

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

Thompson, M.C.; Pierce, R.A.; Ray, R.J.

1998-06-01

The Savannah River Site has enriched uranium (EU) solution which has been stored for almost 10 years since being purified in the second uranium cycle of the H area solvent extraction process. The concentrations in solution are {tilde 6} g/L U and about 0.1 M nitric acid. Residual tributylphosphate in the solutions has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 50 mg/L. Uranium is known to form compounds with DBP which have limited solubility. The potential to form uranium-DBP solids raises a nuclear criticality safety issue. SRTC tests have shown that U-DBP solids will precipitate atmore » concentrations potentially attainable during storage of enriched uranium solutions. Evaporation of the existing EUS solution without additional acidification could result in the precipitation of U-DBP solids if DBP concentration in the resulting solution exceeds 110 ppm at ambient temperature. The same potential exists for evaporation of unwashed 1CU solutions. The most important variables of interest for present plant operations are HNO{sub 3} and DBP concentrations. Temperature is also an important variable controlling precipitation. The data obtained in these tests can be used to set operating and safety limits for the plant. It is recommended that the data for 0 degrees C with 0.5 M HNO{sub 3} be used for setting the limits. The limit would be 80 mg/L which is 3 standard deviations below the average of 86 observed in the tests. The data shows that super-saturation can occur when the DBP concentration is as much as 50 percent above the solubility limit. However, super-saturation cannot be relied on for maintaining nuclear criticality safety. The analytical method for determining DBP concentration in U solutions was improved so that analyses for a solution are accurate to within 10 percent. However, the overall uncertainty of results for periodic samples of the existing EUS solutions was only reduced slightly. Thus, sampling appears to be the largest portion of the uncertainty for EUS sample results, although the number of samples analyzed here is low which could contribution to higher uncertainty. The analytical method can be transferred to the plant analytical labs for more routine analysis of samples.« less

Synthesis and Characterization of Modified BiOCl and Their Application in Adsorption of Low-Concentration Dyes from Aqueous Solution

NASA Astrophysics Data System (ADS)

Zhao, Qihang; Xing, Yongxing; Liu, Zhiliang; Ouyang, Jing; Du, Chunfang

2018-03-01

The synthesis and characterization of BiOCl and Fe3+-grafted BiOCl (Fe/BiOCl) is reported that are developed as efficient adsorbents for the removal of cationic dyes rhodamine B (RhB) and methylene blue (MB) as well as anionic dyes methyl orange (MO) and acid orange (AO) from aqueous solutions with low concentration of 0.01 0.04 mmol/L. Characterizations by various techniques indicate that Fe3+ grafting induced more open porous structure and higher specific surface area. Both BiOCl and Fe/BiOCl with negatively charged surfaces showed excellent adsorption efficiency toward cationic dyes, which could sharply reach 99.6 and nearly 100% within 3 min on BiOCl and 97.0 and 98.0% within 10 min on Fe/BiOCl for removing RhB and MB, respectively. However, Fe/BiOCl showed higher adsorption capacity than BiOCl toward ionic dyes. The influence of initial dye concentration, temperature, and pH value on the adsorption capacity is comprehensively studied. The adsorption process of RhB conforms to Langmuir adsorption isotherm and pseudo-second-order kinetic feature. The excellent adsorption capacities of as-prepared adsorbents toward cationic dyes are rationalized on the basis of electrostatic attraction as well as open porous structure and high specific surface area. In comparison with Fe/BiOCl, BiOCl displays higher selective efficiency toward cationic dyes in mixed dye solutions.

Effect of variation in indium concentration on the photosensitivity of chlorine doped In{sub 2}S{sub 3} thin films

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

Cherian, Angel Susan; Kartha, C. Sudha; Vijayakumar, K. P.

2014-01-28

Consequence of variation in Indium concentration in chlorine doped In2S{sub 3} thin films deposited by spray pyrolysis technique was studied. Chlorine was incorporated in the spray solution, using HCl and Indium concentration was varied by adjusting In/S ratio Interestingly, the photo response of all chlorine doped samples augmented compared to pristine samples; but the highest photosensitivity value of ∼2300 was obtained only when 36ml 0.5M HCl was added to the solution of In{sub 2}S{sub 3} having In/S=2/8. It was also observed that samples with high photosensitivity possess higher band gap and variation in sub band gap absoption levels were observedmore » with increase in Indium concentration. The present study proved that concentration of Indium plays an important role in controlling the crystallinity and photosensitivity of chlorine doped samples.« less

Higher Dialysate Matrix Metalloproteinase-2 Levels Are Associated with Peritoneal Membrane Dysfunction

PubMed Central

Cho, Yeoungjee; Johnson, David W.; Vesey, David A.; Hawley, Carmel M.; Pascoe, Elaine M.; Clarke, Margaret; Topley, Nicholas

2016-01-01

♦ Background: Peritoneal dialysis (PD) patients develop progressive and cumulative peritoneal injury with longer time spent on PD. The present study aimed to a) describe the trend of peritoneal injury biomarkers, matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1), in incident PD patients, b) to explore the capacity of dialysate MMP-2 to predict peritoneal solute transport rate (PSTR) and peritonitis, and c) to evaluate the influence of neutral pH, low glucose degradation product (GDP) PD solution on these outcomes. ♦ Methods: The study included 178 participants from the balANZ trial who had at least 1 stored dialysate sample. Changes in PSTR and peritonitis were primary outcome measures, and the utility of MMP-2 in predicting these outcomes was analyzed using multilevel linear regression and multilevel Poisson regression, respectively. ♦ Results: Significant linear increases in dialysate MMP-2 and TIMP-1 concentrations were observed (p < 0.001), but neither was affected by the type of PD solutions received (MMP-2: p = 0.07; TIMP-1: p = 0.63). An increase in PSTR from baseline was associated with higher levels of MMP-2 (p = 0.02), and the use of standard solutions over longer PD duration (p = 0.001). The risk of peritonitis was independently predicted by higher dialysate MMP-2 levels (incidence rate ratio [IRR] per ng/mL 1.01, 95% confidence interval [CI] 1.005 – 1.02, p = 0.002) and use of standard solutions (Biocompatible solution: IRR 0.45, 95% CI 0.24 – 0.85, p = 0.01). ♦ Conclusion: Dialysate MMP-2 and TIMP-1 concentrations increased with longer PD duration. Higher MMP-2 levels were associated with faster PSTR and future peritonitis risk. Administration of biocompatible solutions exerted no significant effect on dialysate levels of MMP-2 or TIMP-1, but did counteract the increase in PSTR and the risk of peritonitis associated with the use of standard PD solutions. This is the first longitudinal study to examine the clinical utility of MMP-2 as a predictor of patient-level outcomes. PMID:25292407

Association between mortality and replacement solution bicarbonate concentration in continuous renal replacement therapy: A propensity-matched cohort study.

PubMed

Kashani, Kianoush; Thongprayoon, Charat; Cheungpasitporn, Wisit; Iacovella, Gina M; Akhoundi, Abbasali; Albright, Robert C

2017-01-01

Given the known deleterious effects seen with bicarbonate supplementation for acidemia, we hypothesized that utilizing high bicarbonate concentration replacement solution in continuous venovenous hemofiltration (CVVH) would be independently associated with higher mortality. In a propensity score-matched historical cohort study conducted at a single tertiary care center from December 9, 2006, through December 31, 2009, a total of 287consecutive adult critically ill patients with Stage III acute kidney injury (AKI) requiring CVVH were enrolled. We excluded patients on maintenance dialysis, those who received other modalities of continuous renal replacement therapies, and patients that received a mixed of 22 and 32 mEq/L bicarbonate solution pre- and post-filter. The primary outcome was in-hospital and 90-day mortality rates. Among enrollees, 68 were used 32 mEq/L bicarbonate solution, and 219 received 22mEq/L bicarbonate solution for CVVH. Patients on 32 mEq/L bicarbonate solution were more often non-surgical, had lower pH and bicarbonate level but had higher blood potassium and phosphorus levels in comparison with those on 22 mEq/L bicarbonate solution. After adjustment for the baseline characteristics, the use of 32 bicarbonate solution was significantly associated with increased in-hospital (HR = 1.94; 95% CI 1.02-3.79) and 90-day mortality (HR = 1.50; 95% CI 1.03-2.14). There was a significant increase in the hospital (p = .03) and 90-day (p = .04) mortality between the 22 vs. 32 mEq/L bicarbonate solution groups following propensity matching. Our data showed there is a strong association between using high bicarbonate solution and mortality independent of severity of illness and comorbid conditions. These findings need to be evaluated further in prospective studies.

Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis

NASA Astrophysics Data System (ADS)

Inoue, Takashi A.; Hata, Tamako; Asaoka, Kiyoshi; Ito, Tetsuo; Niihara, Kinuko; Hagiya, Hiroshi; Yokohari, Fumio

2012-12-01

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na+, K+, Ca2+, and Mg2+. Based on behavioral analyses, these butterflies preferred a 10-mM Na+ solution to K+, Ca2+, and Mg2+ solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na+ concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na+ solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K+, Ca2+, and/or Mg2+ were higher than that of Na+. This suggests that K+, Ca2+, and Mg2+ do not interfere with the detection of Na+ by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl2 or MgCl2. The dose-response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na+ detected by the contact chemosensilla in the proboscis, which measure its concentration.

Concentrating molasses distillery wastewater using biomimetic forward osmosis (FO) membranes.

PubMed

Singh, N; Petrinic, I; Hélix-Nielsen, C; Basu, S; Balakrishnan, M

2018-03-01

Treatment of sugarcane molasses distillery wastewater is challenging due to the presence of complex phenolic compounds (melanoidins and polyphenols) having antioxidant properties. Due to zero liquid discharge regulations, Indian distilleries continue to explore effective treatment options. This work examines the concentration of distillery wastewater by forward osmosis (FO) using aquaporin biomimetic membranes and magnesium chloride hexahydrate (MgCl 2 .6H 2 O) as draw solution. The operational parameters viz. feed solution and draw solution flow rate and draw solution concentration were optimized using 10% v/v melanoidins model feed solution. This was followed by trials with distillery wastewater. Under the conditions of this work, feed and draw flow rates of 1 L/min and draw solution concentration of 2M MgCl 2 .6H 2 O for melanoidins model solution and 3M MgCl 2 .6H 2 O for distillery wastewater were optimal for maximum rejection. Rejection of 90% melanoidins, 96% antioxidant activity and 84% COD was obtained with melanoidins model feed, with a corresponding water flux of 6.3 L/m 2 h. With as-received distillery wastewater, the rejection was similar (85-90%) to the melanoidins solution, but the water flux was lower (2.8 L/m 2 h). Water recovery from distillery wastewater over 24 h study period was higher with FO (70%) than reported for RO (35-45%). Repeated use of the FO membrane over five consecutive 24 h cycles with fresh feed and draw solutions and periodic cleaning showed consistent average water flux and rejection of the feed constituents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Critical zone structure controls concentration-discharge relationships and solute generation in forested tropical montane watersheds

NASA Astrophysics Data System (ADS)

Wymore, Adam S.; Brereton, Richard L.; Ibarra, Daniel E.; Maher, Kate; McDowell, William H.

2017-07-01

Concentration-discharge (C-Q) relationships are poorly known for tropical watersheds, even though the tropics contribute a disproportionate amount of solutes to the global ocean. The Luquillo Mountains in Puerto Rico offer an ideal environment to examine C-Q relationships across a heterogeneous tropical landscape. We use 10-30 years of weekly stream chemistry data across 10 watersheds to examine C-Q relationships for weathering products (SiO2(aq), Ca2+, Mg2+, and Na+) and biologically controlled solutes (dissolved organic carbon [DOC], dissolved organic nitrogen [DON], NH4+, NO3-, PO43-, K+, and SO42-). We analyze C-Q relationships using power law equations and a solute production model and use principal component analysis to test hypotheses regarding how the structure of the critical zone controls solute generation. Volcaniclastic watersheds had higher concentrations of weathering solutes and smaller tributaries were approximately threefold more efficient at generating these solutes than larger rivers. Lithology and vegetation explained a significant amount of variation in the theoretical maximum concentrations of weathering solutes (r2 = 0.43-0.48) and in the C-Q relationships of PO43- (r2 = 0.63) and SiO2(aq) (r2 = 0.47). However, the direction and magnitude of these relationships varied. Across watersheds, various forms of N and P displayed variable C-Q relationships, while DOC was consistently enriched with increasing discharge. Results suggest that PO43- may be a useful indicator of watershed function. Relationships between C-Q and landscape characteristics indicate the extent to which the structure and function of the Critical zone controls watershed solute fluxes.

Electrochemical synthesis of one-dimensional ZnO nanostructures on ZnO seed layer for DSSC applications

NASA Astrophysics Data System (ADS)

Marimuthu, T.; Anandhan, N.; Thangamuthu, R.

2018-01-01

Electrochemical deposition of vertically aligned zinc oxide (ZnO) nanorods were prepared on ZnO seeded fluorine doped tin oxide (FTO) substrate in the solutions consisting of different concentrations of hexamethylenetetramine (HMTA). The electrochemical, structural, morphological, vibrational and optical properties were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy and photoluminescence (PL) spectroscopy, respectively. CV curves confirm that metallic zinc phase is not deposited as the HMTA concentration is about 9 mM in a deposition solution. XRD patterns of the as-prepared films show that the increasing HMTA concentrations from 0 mM to 9 mM not only increase the formation of zinc hydrate chloride (Zn5(OH)8Cl2·H2O) but also decrease and finally disappear the metallic Zn deposition. After the as-prepared films annealed at 450 ° C, the crystalline phases of Zn and Zn5(OH)8Cl2·H2O are completely converted to ZnO hexagonal wurtzite phase with high intense growth (002) plane orientation. SEM images support that the vertical growth of ZnO nanostructures (nanorods and petals) with a few flowers is found to be in the cordillera structure as the films are deposited in the solutions consisting of 3 mM, 6 mM and 9 mM HMTA respectively. Raman and PL spectra confirm that the ZnO film deposited in the solution consisting of 9 mM HMTA has a higher crystalline nature with lesser atomic defects and is also higher c-axis growth than that of other films deposited in the solutions consisting of 0 mM, 3 mM and 6 mM, respectively. UV-vis absorbance spectra corroborate that the ZnO film deposited in the solution consisting of 9 mM HMTA shows a high dye absorbance as compared with other films. The efficiency of DSSCs based on ZnO photoanodes deposited in the solutions consisting of 0 mM and 9 mM HMTA was 1.79 and 3.75%, respectively. Electrochemical impedance spectra revealed that DSSC based on ZnO photoanode deposited in the solution consisting of 9 mM HMTA has a higher charge recombination resistance (Rrec) than that of another DSSC.

Conversion of Isatin to Isatate as Related to Growth Promotion in Avena Coleoptile and Pisum Stem Sections 1

PubMed Central

Chen, H.-R.; Galston, A. W.; Milstone, L.

1966-01-01

Isatin, (indole 2,3-dione), which promotes elongation of Pisum stem sections at concentrations exceeding 0.1 mm, promotes elongation of Avena coleoptile sections only at higher concentrations, exceeding 1 mm. Aged isatin solutions are more active than fresh solutions, due to the slow, spontaneous conversion to isatate (o-aminophenylglyoxylate). A concentration of 0.1 mm aged isatin is as active in Avena coleoptile sections as in peas. Isatate has been independently synthesized and its auxin activity in both Avena coleoptile and Pisum stem sections confirmed. The synthetic isatate is more effective than isatin in both systems. This suggests that the auxin activity of isatin is due to its conversion to isatate. PMID:16656429

Investigation of transition from thermal- to solutal-Marangoni flow in dilute alcohol/water mixtures using nano-plasmonic heaters

NASA Astrophysics Data System (ADS)

Namura, Kyoko; Nakajima, Kaoru; Suzuki, Motofumi

2018-02-01

We experimentally investigated Marangoni flows around a microbubble in diluted 1-butanol/water, 2-propanol/water, and ethanol/water mixtures using the thermoplasmonic effect of gold nanoisland film. A laser spot on the gold nanoisland film acted as a highly localized heat source that was utilized to generate stable air microbubbles with diameters of 32-48 μm in the fluid and to induce a steep temperature gradient on the bubble surface. The locally heated bubble has a flow along the bubble surface, with the flow direction showing a clear transition depending on the alcohol concentrations. The fluid is driven from the hot to cold regions when the alcohol concentration is lower than the transition concentration, whereas it is driven from the cold to hot regions when the concentration is higher than the transition concentration. In addition, the transition concentration increases as the carbon number of the alcohol decreases. The observed flow direction transition is explained by the balance of the thermal- and solutal-Marangoni forces that are cancelled out for the transition concentration. The selective evaporation of the alcohol at the locally heated surface allows us to generate stable and rapid thermoplasmonic solutal-Marangoni flows in the alcohol/water mixtures.

Reclamation of cadmium-contaminated soil using dissolved organic matter solution originating from wine-processing waste sludge.

PubMed

Liu, Cheng-Chung; Chen, Guan-Bu

2013-01-15

Soil washing using an acid solution is a common practice for removing heavy metals from contaminated soil in Taiwan. However, serious loss of nutrients from soil is a major drawback of the washing. Distillery sludge can be used to prepare a dissolved organic matter (DOM) solution by extracting its organic constituents with alkaline solutions. This study employed DOM solutions to remediate Cd-contaminated soil (with concentrations up to 21.5 mg kg(-1)) and determine the factors affecting removal of Cd, such as pH, initial concentration of DOM solution, temperature, and washing frequency. When washing with pH 3.0 and 1250 mg L(-1) DOM solution, about 80% and 81% of Cd were removed from the topsoil at 27 °C and subsoil at 40 °C, respectively. To summarize the changes in fertility during DOM washing with various pH solutions: the increase in organic matter content ranged from 7.7% to 23.7%; cation exchange capacity (CEC) ranged from 4.6% to 13.9%; available ammonium (NNH(4)) content ranged from 39.4% to 2175%; and available phosphorus content ranged from 34.5% to 182%. Exchangeable K, Ca, and Mg remained in the topsoil after DOM washing, with concentrations of 1.1, 2.4, and 1.5 times higher than those treated with HCl solution at the same pH, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of PVDF concentration on the properties of PVDF membranes

NASA Astrophysics Data System (ADS)

Pramono, E.; Simamora, A. L.; Radiman, C. L.; Wahyuningrum, D.

2017-07-01

Polyvinylideneflouride (PVDF) is a good polymeric material for preparing ultrafiltration and microfiltration membranes due to its high mechanical properties and chemical resistance. The objective of this work is to study the effects of PVDF concentration on the membrane properties such as mechanical strength, permeability of water and permselectivity of T-500 and T-2000 dextran solutions. These membranes were also characterized by contact angle determination and its morphology was observed by scanning electron microscopy (SEM). From the experimental data, it can be concluded that PVDF concentration affects the surface properties, permeability and permselectivity of the produced membranes. Higher PVDF concentrations results in higher hydrophobicity, mechanical properties and rejection towards T-500 and T-2000 dextrans, but lower water flux.

[Dynamics of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan].

PubMed

Yin, Guangcai; Zhou, Guoyi; Zhang, Deqiang; Wang, Xu; Chu, Guowei; Liu, Yan

2005-09-01

The total flux and concentration of total organic carbon (TOC) in hydrological processes in coniferous and broad-leaved mixed forest of Dinghushan were measured from July 2002 to July 2003. The results showed that the TOC input by precipitation was 41.80 kg x hm(-2) x yr(-1), while its output by surface runoff and groundwater (soil solution at 50 cm depth) was 17.54 and 1.80 kg x hm(-2) x yr(-1), respectively. The difference between input and output was 22.46 kg x hm(-2) x yr(-1), indicating that the ecosystem TOC was in positive balance. The monthly variation of TOC flux in hydrological processes was very similar to that in precipitation. The mean TOC concentration in precipitation was 3.64 mg x L(-1), while that in throughfall and stemflow increased 6.10 and 7.39 times after rain passed through the tree canopies and barks. The mean TOC concentration in surface runoff and in soil solution at 25 and 50 cm depths was 12.72, 7.905 and 3.06 mg x L(-1), respectively. The monthly TOC concentration in throughfall and stemflow had a similar changing tendency, showing an increase at the beginning of growth season (March), a decrease after September, and a little increase in December. The TOC concentration in runoff was much higher during high precipitation months. No obvious monthly variation was observed in soil solution TOC concentration (25 and 50 cm below the surface). Stemflow TOC concentration differed greatly between different tree species. The TOC concentration in precipitation, throughfall, and soil solution (25 and 50 cm depths) decreased with increasing precipitation, and no significant relationship existed between the TOC concentrations in stemflow, surface runoff and precipitation. The TOC concentrations in the hydrological processes fluctuated with precipitation intensity, except for that in stemflow and soil solutions.

Influence of humic acid on the removal of arsenate and arsenic by ferric chloride: effects of pH, As/Fe ratio, initial As concentration, and co-existing solutes.

PubMed

Kong, Yanli; Kang, Jing; Shen, Jimin; Chen, Zhonglin; Fan, Leitao

2017-01-01

The influence of humic acid (HA) on the removal of arsenic by FeCl 3 was systematically studied in this paper. Jar tests were performed to investigate the influence on arsenic during FeCl 3 coagulation of the pH adjusting method, the initial As/Fe ratio, the equilibrium As concentration, and co-occurring anions and cations. Compared with results in HA-free systems, the removal trends of arsenic in HA solutions were quite different. It was found that As(V) removal was higher at low equilibrium concentration, yet the opposite was true for As(III) removal. The presence of HA influenced the effective number of active sites for arsenic removal by FeCl 3 flocculation. In addition, in the presence of HA, the impacts of co-existing solutions on arsenic removal were also different from that of an HA-free system. This study examined the influence of co-occurring anions, such as phosphate, sulfate, and silicate on arsenic removal, depending on their ability to compete for sorption sites and to hinder or facilitate the aggregation of ferric hydroxide flocs. The presence of Ca 2+ or Cd 2+ significantly increased arsenic removal at higher pH. Low concentrations of dissolved HA and high concentrations of colloid affected the adsorption of arsenic onto iron oxide. The influence of HA on the adsorption of arsenic onto iron oxide primarily depended on the relative content of the dissolved and mineral combination states of HA and the interface combination forms.

Suppression of vacancy cluster growth in concentrated solid solution alloys

DOE PAGES

Zhao, Shijun; Velisa, Gihan; Xue, Haizhou; ...

2016-12-13

Large vacancy clusters, such as stacking-fault tetrahedra, are detrimental vacancy-type defects in ion-irradiated structural alloys. Suppression of vacancy cluster formation and growth is highly desirable to improve the irradiation tolerance of these materials. In this paper, we demonstrate that vacancy cluster growth can be inhibited in concentrated solid solution alloys by modifying cluster migration pathways and diffusion kinetics. The alloying effects of Fe and Cr on the migration of vacancy clusters in Ni concentrated alloys are investigated by molecular dynamics simulations and ion irradiation experiment. While the diffusion coefficients of small vacancy clusters in Ni-based binary and ternary solid solutionmore » alloys are higher than in pure Ni, they become lower for large clusters. This observation suggests that large clusters can easily migrate and grow to very large sizes in pure Ni. In contrast, cluster growth is suppressed in solid solution alloys owing to the limited mobility of large vacancy clusters. Finally, the differences in cluster sizes and mobilities in Ni and in solid solution alloys are consistent with the results from ion irradiation experiments.« less

Preparation of metallic nanoparticles by irradiation in starch aqueous solution

NASA Astrophysics Data System (ADS)

NemÅ£anu, Monica R.; Braşoveanu, Mirela; Iacob, Nicuşor

2014-11-01

Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔEab (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle ho was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.

Taste does not determine daily intake of dilute sugar solutions in mice

PubMed Central

Beltran, F.; Benton, L.; Cheng, S.; Gieseke, J.; Gillman, J.; Spain, H. N.

2010-01-01

When a rodent licks a sweet-tasting solution, taste circuits in the central nervous system that facilitate stimulus identification, motivate intake, and prepare the body for digestion are activated. Here, we asked whether taste also determines daily intake of sugar solutions in C57BL/6 mice. We tested several dilute concentrations of glucose (167, 250, and 333 mM) and fructose (167, 250, and 333 mM). In addition, we tested saccharin (38 mM), alone and in binary mixture with each of the sugar concentrations, to manipulate sweet taste intensity while holding caloric value constant. In experiment 1, we measured taste responsiveness to the sweetener solutions in two ways: chorda tympani nerve responses and short-term lick tests. For both measures, the mice exhibited the following relative magnitude of responsiveness: binary mixtures > saccharin > individual sugars. In experiment 2, we asked whether the taste measures reliably predicted daily intake of the sweetener solutions. No such relationship was observed. The glucose solutions elicited weak taste responses but high daily intakes, whereas the fructose solutions elicited weak taste responses and low daily intakes. On the other hand, the saccharin + glucose solutions elicited strong taste responses and high daily intakes, while the saccharin + fructose solutions elicited strong taste responses but low daily intakes. Overall, we found that 1) daily intake of the sweetener solutions varied independently of the magnitude of the taste responses and 2) the solutions containing glucose stimulated substantially higher daily intakes than did the solutions containing isomolar concentrations of fructose. Given prior work demonstrating greater postoral stimulation of feeding by glucose than fructose, we propose that the magnitude of postoral nutritive stimulation plays a more important role than does taste in determining daily intake of dilute sugar solutions. PMID:20702804

Influence of chitosan concentration on mechanical and barrier properties of corn starch/chitosan films.

PubMed

Ren, Lili; Yan, Xiaoxia; Zhou, Jiang; Tong, Jin; Su, Xingguang

2017-12-01

The active packaging films based on corn starch and chitosan were prepared through mixing the starch solution and the chitosan solution (1:1) by casting. The aim of this work was to characterize and analyze the effects of the chitosan concentrations (0, 21, 41, 61 and 81wt% of starch) on physicochemical, mechanical and water vapor barrier properties as well as morphological characteristics of the corn starch/chitosan (CS/CH) films. Starch molecules and chitosan could interact through hydrogen bonding as confirmed from the shift of the main peaks to higher wavenumbers in FTIR and the reduction of crystallinity in XRD. Results showed that the incorporation of chitosan resulted in an increase in film solubility, total color differences, tensile strength and elongation at break and a decrease in Young's modulus and water vapor permeability (WVP). Elongation at break of the CS/CH films increased with increasing of chitosan concentration, and reached a maximum at 41 wt%, then declined at higher chitosan concentration. The WVP of CS/CH films increased with an increase of chitosan concentration and the same tendency observed for the moisture content. The results suggest that this biodegradable CS/CH films could potentially be used as active packaging films for food and pharmaceutical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Self-assembling Structures and Sol-Gel Transition of Optically Active and Racemic 12-Hydroxystearic Acids in Organic Solvents

NASA Astrophysics Data System (ADS)

Takeno, Hiroyuki; Mochizuki, Tomomitsu; Yoshiba, Kazuto; Kondo, Shingo; Dobashi, Toshiaki

Self-assembling structures and sol-gel transition in solution of optically active and racemic 12-Hydroxystearic acids (HSA) have been investigated by means of small-angle X-ray scattering (SAXS), differential scanning calorimetry and rheological measurements. Apparently two kinds of gel, transparent gel and turbid gel were obtained in different solvents or by changing concentrations in the same solvent. The melting temperature of the turbid gel is higher than that of the transparent gel. The difference can be qualitatively explained by the dissolution of the crystals (melting point depression) in non-ideal solutions. The SAXS profiles of the transparent gel composed of fibrillar structures have a similar shape at different concentrations, although the intensity is larger for the gels with higher concentrations of 12-HSA. The SAXS analysis reveals that the cross-section of fibrils have square or circular shape (no anisotropic shape) with the radius of gyration 83 Å. On the other hand, for the turbid gel structural inhomnogeneity becomes significant with concentration. The gelation properties and the structures are found to be similar in the racemic HSA gel and the optically active (D-HSA) gel.

Modeling preferential water flow and solute transport in unsaturated soil using the active region model

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

Sheng, F.; Wang, K.; Zhang, R.

2009-03-15

Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared withmore » the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.« less

The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH3 gas

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

Katsenovich, Yelena P.; Cardona, Claudia; Lapierre, Robert

2016-10-01

Remediation of uranium in the deep unsaturated zone is a challenging task, especially in the presence of oxygenated, high-carbonate alkalinity soil and pore water composition typical for arid and semi-arid environments of the western regions of the U.S. This study evaluates the effect of various pore water constituencies on changes of uranium concentrations in alkaline conditions, created in the presence of reactive gases such as NH3 to effectively mitigate uranium contamination in the vadose zone sediments. This contaminant is a potential source for groundwater pollution through slow infiltration of soluble and highly mobile uranium species towards the water table. Themore » objective of this research was to evaluate uranium sequestration efficiencies in the alkaline synthetic pore water solutions prepared in a broad range of Si, Al, and bicarbonate concentrations typically present in field systems of the western U.S. regions and identify solid uranium-bearing phases that result from ammonia gas treatment. In previous studies (Szecsody et al. 2012; Zhong et al. 2015), although uranium mobility was greatly decreased, solid phases could not be identified at the low uranium concentrations in field-contaminated sediments. The chemical composition of the synthetic pore water used in the experiments varied for silica (5–250 mM), Al3+ (2.8 or 5 mM), HCO3- (0–100 mM) and U(VI) (0.0021–0.0084 mM) in the solution mixture. Experiment results suggested that solutions with Si concentrations higher than 50 mM exhibited greater removal efficiencies of U(VI). Solutions with higher concentrations of bicarbonate also exhibited greater removal efficiencies for Si, Al, and U(VI). Overall, the silica polymerization reaction leading to the formation of Si gel correlated with the removal of U(VI), Si, and Al from the solution. If no Si polymerization was observed, there was no U removal from the supernatant solution. Speciation modeling indicated that the dominant uranium species in the presence of bicarbonate were anionic uranyl carbonate complexes (UO2(CO3)2-2 and UO2(CO3)3-4) and in the absence of bicarbonate in the solution, U(VI) major species appeared as uranyl-hydroxide (UO2(OH)3- and UO2(OH)4-2) species. The model also predicted the formation of uranium solid phases. Uranyl carbonates as rutherfordine [UO2CO3], cejkaite [Na4(UO2)(CO3)3] and hydrated uranyl silicate phases as Na-boltwoodite [Na(UO2)(SiO4)·1.5H2O] were anticipated for most of the synthetic pore water compositions amended from medium (2.9 mM) to high (100 mM) bicarbonate concentrations.« less

Inactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine

USGS Publications Warehouse

Hershberger, P.K.; Pacheco, C.A.; Gregg, J.L.

2008-01-01

Chlorine and iodine solutions were effective at inactivating Ichthyophonus spores in vitro. Inactivation in sea water increased directly with halogen concentration and exposure duration, with significant differences (P < 0.05) from controls occurring at all chlorine concentrations and exposure durations tested (1.5-13.3 ppm for 1-60 min) and at most iodine concentrations and exposure durations tested (1.2 ppm for 60 min and 5.9-10.7 ppm for 1-60 min). However, 10-fold reductions in spore viability occurred only after exposure to halogen solutions at higher concentrations and/or longer durations (13 ppm total chlorine for 1-60 min, 5.9 ppm total iodine for 60 min, and 10.7 ppm total iodine for 1-60 min). Inactivation efficacy was greater when halogen solutions were prepared in fresh water, presumably because of combined effects of halogen-induced inactivation and general spore instability in fresh water. The results have practical implications for disinfection and biocontainment in research laboratories and other facilities that handle live Ichthyophonus cultures and/or infected fish.

Effectiveness of dishwashing liquids in removing chlorothalonil and chlorpyrifos residues from cherry tomatoes.

PubMed

Wang, Zhiwei; Huang, Jiexun; Chen, Jinyuan; Li, Feili

2013-08-01

Washing is the most practical way to remove pesticide residues in fruits and vegetables. Two commonly used kitchen dishwashing liquids (detergents) in Chinese market were tested for enhanced removal of chlorpyrifos (CHP) and chlorothalonil (CHT) in cherry tomatoes by soaking the cherry tomatoes in the detergent solutions. The critical micelle concentrations of detergent A and detergent B were about 250 mg L(-1) and 444 mg L(-1), respectively. Detergent A had a higher solubilizing ability for pesticides and hence washing effectiveness than detergent B. The apparent solubility of CHP increased with increasing detergent concentration, while that of CHT remained comparatively invariant independent of detergent concentration within the tested range. The apparent solubility of CHP was also consistently higher in solutions of both detergents as compared to CHT. Due probably to its lower logKow value, CHT was more readily washed off cherry tomatoes than CHP. In terms of washing, a duration of 10-20 min was sufficient for removal of pesticides on cherry tomatoes in distilled water and detergent solutions. The effectiveness of removing pesticides increased with increasing detergent concentration from 50 mg L(-1) to 5 g L(-1), with up to 80% CHT and 42% CHP removed. Multiple washing further increased pesticide removal. Adding 10% acetic acid to lower pH or increasing washing temperature favored pesticide removal, but 10% NaCl produced the shielding effect and substantially reduced the effectiveness of detergent A for pesticide removal. Copyright © 2013 Elsevier Ltd. All rights reserved.

Absorption of Carbon Dioxide in Aqueous Solutions of N-methyldiethanolamine Mixtures

NASA Astrophysics Data System (ADS)

Ma’mun, S.; Svendsen, H. F.

2018-05-01

Carbon dioxide (CO2) is one of the greenhouse gases (GHG) that has contributed to the global warming problem. Carbon dioxide is produced in large quantity from coal-fired power plants, iron and steel production, cement production, chemical and petrochemical industries, natural gas purification, and transportation. Some efforts to reduce the CO2 emissions to the atmosphere are then required. Amine-based absorption may be an option for post-combustion capture. The objective of this study is to measure the effect of promoter addition as well as MDEA concentration for the CO2 absorption into the aqueous solutions of MDEA to improve its performances, i.e. increasing the absorption rate and the absorption capacity. Absorption of CO2 in aqueous solutions of MDEA mixtures were measured at 40 °C in a bubble tank reactor. The systems tested were the mixtures of 30 wt% MDEA with 5 and 10 wt% BEA and the mixtures of 40 and 50 wt% MDEA with 6 wt% AEEA. It was found that for MDEA-BEA-H2O mixtures, the higher the promoter concentraation the higher the CO2 absorption rate, while for the MDEA-AEEA-H2O mixtures, the higher the MDEA concentration the lower the CO2 absorption rate.

NMR investigations of self-aggregation characteristics of SDS in a model assembled tri-block copolymer solution.

PubMed

Kumar, B V N Phani; Priyadharsini, S Umayal; Prameela, G K S; Mandal, Asit Baran

2011-08-01

The present work was undertaken with a view to understand the influence of a model non-ionic tri-block copolymer PEO-PPO-PEO (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)) with molecular weight 5800 i.e., P123 [(EO)(20)-(PO)(70)-(EO)(20)] on the self-aggregation characteristics of the anionic surfactant sodium dodecylsulfate (SDS) in aqueous solution (D(2)O) using NMR chemical shift, self-diffusion and nuclear spin-relaxation as suitable experimental probes. In addition, polymer diffusion has been monitored as a function of SDS concentration. The concentration-dependent chemical shift, diffusion data and relaxation data indicated the significant interaction of polymeric micelles with SDS monomers and micelles at lower and intermediate concentrations of SDS, whereas the weak interaction of the polymer with SDS micelles at higher concentrations of SDS. It has been observed that SDS starts aggregating on the polymer at a lower concentration i.e., critical aggregation concentration (cac=1.94 mM) compared to polymer-free situation, and the onset of secondary micelle concentration (C(2)=27.16 mM) points out the saturation of the 0.2 wt% polymer or free SDS monomers/micelles at higher concentrations of SDS. It has also been observed that the parameter cac is almost independent in the polymer concentrations of study. The TMS (tetramethylsilane) has been used as a solubilizate to measure the bound diffusion coefficient of SDS-polymer mixed system. The self-diffusion data were analyzed using two-site exchange model and the obtained information on aggregation dynamics was commensurate with that inferred from chemical shift and relaxation data. The information on slow motions of polymer-SDS system was also extracted using spin-spin and spin-lattice relaxation rate measurements. The relaxation data points out the disintegration of polymer network at higher concentrations of SDS. The present NMR investigations have been well corroborated by surface tension and conductivity measurements. Copyright © 2011 Elsevier Inc. All rights reserved.

The Role of Concentration and Solvent Character in the Molecular Organization of Humic Acids.

PubMed

Klučáková, Martina; Věžníková, Kateřina

2016-10-27

The molecular organization of humic acids in different aqueous solutions was studied over a wide concentration range (0.01-10 g·dm -3 ). Solutions of humic acids were prepared in three different media: NaOH, NaCl, and NaOH neutralized by HCl after dissolution of the humic sample. Potentiometry, conductometry, densitometry, and high resolution ultrasound spectrometry were used in order to investigate conformational changes in the humic systems. The molecular organization of humic acids in the studied systems could be divided into three concentration ranges. The rearrangements were observed at concentrations of ~0.02 g·dm -3 and ~1 g·dm -3 . The first "switch-over point" was connected with changes in the hydration shells of humic particles resulting in changes in their elasticity. The compressibility of water in the hydration shells is less than the compressibility of bulk water. The transfer of hydration water into bulk water increased the total compressibility of the solution, reducing the ultrasonic velocity. The aggregation of humic particles and the formation of rigid structures in systems with concentrations higher than 1 g·dm -3 was detected.

[Effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter in soil solution in a young Cunninghamia lanceolata plantation.

PubMed

Yuan, Xiao Chun; Chen, Yue Min; Yuan, Shuo; Zheng, Wei; Si, You Tao; Yuan, Zhi Peng; Lin, Wei Sheng; Yang, Yu Sheng

2017-01-01

To study the effects of nitrogen deposition on the concentration and spectral characteristics of dissolved organic matter (DOM) in the forest soil solution from the subtropical Cunninghamia lanceolata plantation, using negative pressure sampling method, the dynamics of DOM in soil solutions from 0-15 and 15-30 cm soil layer was monitored for two years and the spectroscopic features of DOM were analyzed. The results showed that nitrogen deposition significantly reduced the concentration of dissolved organic carbon (DOC), and increased the aromatic index (AI) and the humic index (HIX), but had no significant effect on dissolved organic nitrogen (DON) concentration in both soil layers. There was obvious seasonal variation in DOM concentration of the soil solution, which was prominently higher in summer and autumn than in spring and winter.Fourier-transform infrared (FTIR) absorption spectrometry indicated that the DOM in forest soil solution had absorption peaks in the similar position of six regions, being the highest in wave number of 1145-1149 cm -1 . Three-dimensional fluorescence spectra indicated that DOM was mainly consisted of protein-like substances (Ex/Em=230 nm/300 nm) and microbial degradation products (Ex/Em=275 nm/300 nm). The availability of protein-like substances from 0-15 cm soil layer was reduced in the nitrogen treatments. Nitrogen deposition significantly reduced the concentration of DOC in soil solution, maybe largely by reducing soil pH, inhibiting soil carbon mineralization and stimulating plant growth. In particular, the decline of DOC concentration in the surface layer was due to the production inhibition of the protein-like substances and carboxylic acids. Short-term nitrogen deposition might be beneficial to the maintenance of soil fertility, while the long-term accumulation of nitrogen deposition might lead to the hard utilization of soil nutrients.

Analyzing the effects of instillation volume on intravesical delivery using biphasic solute transport in a deformable geometry.

PubMed

Smith, Sean G; Griffith, Boyce E; Zaharoff, David A

2018-04-05

Ailments of the bladder are often treated via intravesical delivery-direct application of therapeutic into the bladder through a catheter. This technique is employed hundreds of thousands of times every year, but protocol development has largely been limited to empirical determination. Furthermore, the numerical analyses of intravesical delivery performed to date have been restricted to static geometries and have not accounted for bladder deformation. This study uses a finite element analysis approach with biphasic solute transport to investigate several parameters pertinent to intravesical delivery including solute concentration, solute transport properties and instillation volume. The volume of instillation was found to have a substantial impact on the exposure of solute to the deeper muscle layers of the bladder, which are typically more difficult to reach. Indeed, increasing the instillation volume from 50-100 ml raised the muscle solute exposure as a percentage of overall bladder exposure from 60-70% with higher levels achieved for larger instillation volumes. Similar increases were not seen for changes in solute concentration or solute transport properties. These results indicate the role that instillation volume may play in targeting particular layers of the bladder during an intravesical delivery.

Physical Compatibility of Calcium Chloride and Sodium Glycerophosphate in Pediatric Parenteral Nutrition Solutions.

PubMed

Anderson, Collin; MacKay, Mark

2016-11-01

Calcium and phosphate precipitation is an ongoing concern when compounding pediatric parenteral nutrition (PN) solutions. Considerable effort has been expended in producing graphs, tables, and equations to guide the practitioner in prescribing PN that will remain stable. Calcium gluconate is preferred over calcium chloride when compounding PN because of its superior compatibility with inorganic phosphates. PN solutions containing calcium gluconate carry a higher aluminum load than equivalent solutions compounded with calcium chloride, leading to increased potential for aluminum toxicity. This study tested the solubility of calcium chloride in PN solutions compounded with an organic phosphate component, sodium glycerophosphate (NaGP), in place of sodium phosphate. Five PN solutions were compounded by adding calcium chloride at 10, 20, 30, 40, and 50 mEq/L and corresponding concentrations of NaGP at 10, 20, 30, 40, and 50 mmol/L. Each of the 5 solutions was compounded using 1.5% and 4% amino acids, cysteine, and lipids. The physical stability was evaluated by visual inspection (precipitation, haze, and color change). Solutions were evaluated microscopically for any microcrystals using U.S. Pharmacopeia <788> standards. Compatibility testing showed no changes in the PN solution in any of the concentrations tested. Calcium chloride was found to be physically compatible with NaGP in PN at the tested concentrations. Utilization of NaGP in PN solutions would eliminate the need for precipitation curves and allow for the use of calcium chloride. Compounding with NaGP and calcium chloride allows the practitioner a mechanism for reducing the aluminum load in PN. © 2015 American Society for Parenteral and Enteral Nutrition.

Degradation of selected organophosphate pesticides in wastewater by dielectric barrier discharge plasma.

PubMed

Hu, Yingmei; Bai, Yanhong; Yu, Hu; Zhang, Chunhong; Chen, Jierong

2013-09-01

In this paper, degradation of selected organophosphate pesticides (dichlorvos and dimethoate) in wastewater by dielectric barrier discharge plasma (DBD) was studied. DBD parameters, i.e. discharge powers and air-gap distances, differently affect their degradation efficiency. The results show that better degradation efficiency is obtained with a higher discharge power and a shorter air-gap distance. The effect of radical intervention degradation was also investigated by adding radical scavenger (tert-butyl alcohol) to the pesticide solution during the experiments. The result shows that the degradation efficiency is restrained in the presence of radical scavenger. It clearly demonstrates that hydroxyl radicals are most likely the main driver for degradation process. Moreover, the kinetics indicate that the disappearance rate of pesticides follows the first-order rate law when the initial concentration of the solution is low, but shifts to zero-order at a higher initial concentration.

Capacitive Neutralization Dialysis for Direct Energy Generation.

PubMed

Liu, Yue; Zhang, Yi; Ou-Yang, Wei; Bastos Sales, Bruno; Sun, Zhuo; Liu, Fei; Zhao, Ran

2017-08-15

Capacitive neutralization dialysis energy (CNDE) is proposed as a novel energy-harvesting technique that is able to utilize waste acid and alkaline solutions to produce electrical energy. CNDE is a modification based on neutralization dialysis. It was found that a higher NaCl concentration led to a higher open-circuit potential when the concentrations of acid and alkaline solutions were fixed. Upon closing of the circuit, the membrane potential was used as a driving force to move counter ions into the electrical double layers at the electrode-liquid interface, thereby creating an ionic current. Correspondingly, in the external circuit, electrons flow through an external resistor from one electrode to the other, thereby generating electrical energy directly. The influence of external resistances was studied to achieve greater energy extraction, with the maximum output of 110 mW/m 2 obtained by employing an external resistance of 5 Ω together with the AC-coated electrode.

The three-dimensional structure of diaminopimelate decarboxylase from Mycobacterium tuberculosis reveals a tetrameric enzyme organisation.

PubMed

Weyand, Simone; Kefala, Georgia; Svergun, Dmitri I; Weiss, Manfred S

2009-09-01

The three-dimensional structure of the enzyme diaminopimelate decarboxylase from Mycobacterium tuberculosis has been determined in a new crystal form and refined to a resolution of 2.33 A. The monoclinic crystals contain one tetramer exhibiting D(2)-symmetry in the asymmetric unit. The tetramer exhibits a donut-like structure with a hollow interior. All four active sites are accessible only from the interior of the tetrameric assembly. Small-angle X-ray scattering indicates that in solution the predominant oligomeric species of the protein is a dimer, but also that higher oligomers exist at higher protein concentrations. The observed scattering data are best explained by assuming a dimer-tetramer equilibrium with about 7% tetramers present in solution. Consequently, at the elevated protein concentrations in the crowded environment inside the cell the observed tetramer may constitute the biologically relevant functional unit of the enzyme.

In-situ caustic generation from sewage: the impact of caustic strength and sewage composition.

PubMed

Pikaar, Ilje; Rozendal, René A; Rabaey, Korneel; Yuan, Zhiguo

2013-10-01

Periodic caustic dosage is a commonly used method by the water industry to elevate pH levels and deactivate sewer biofilms responsible for hydrogen sulfide generation. Caustic (NaOH) can be generated in-situ from sewage using a divided electrochemical cell, which avoids the need for transport, handling and storage of concentrated caustic solutions. In this study, we investigated the impact of caustic strength in the cathode compartment and the impact of sodium concentration in sewage on the Coulombic efficiency (CE) for caustic generation. The CE was found to be independent of the caustic strength produced in the range of up to ~3 wt%. Results showed that a caustic solution of ~3 wt% could be produced directly from sewage at a CE of up to 75 ± 0.5%. The sodium concentration in sewage had a significant impact on the CE for caustic generation as well as on the energy requirements of the system, with a higher sodium concentration leading to a higher CE and lower energy consumption. The proton, calcium, magnesium and ammonium concentrations in sewage affected the CE for caustic generation, especially at low sodium concentrations. Economical assessment based on the experimental results indicated that sulfide control in sewers using electrochemically-generated caustic from sewage is an economically attractive strategy. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ultrasound degradation of xanthan polymer in aqueous solution: Its scission mechanism and the effect of NaCl incorporation.

PubMed

Saleh, H M; Annuar, M S M; Simarani, K

2017-11-01

Degradation of xanthan polymer in aqueous solution by ultrasonic irradiation was investigated. The effects of selected variables i.e. sonication intensity, irradiation time, concentration of xanthan gum and molar concentration of NaCl in solution were studied. Combined approach of full factorial design and conventional one-factor-at-a-time was applied to obtain optimum degradation at sonication power intensity of 11.5Wcm -2 , irradiation time 120min and 0.1gL -1 xanthan in a salt-free solution. Molecular weight reduction of xanthan gum under sonication was described by an exponential decay function with higher rate constant for polymer degradation in the salt free solution. The limiting molecular weight where fragments no longer undergo scission was determined from the function. The incorporation of NaCl in xanthan solution resulted in a lower limiting molecular weight. The ultrasound-mediated degradation of aqueous xanthan polymer chain agreed with a random scission model. Side chain of xanthan polymer is proposed to be the primary site of scission action. Copyright © 2017 Elsevier B.V. All rights reserved.

Closantel nano-encapsulated polyvinyl alcohol (PVA) solutions.

PubMed

Vega, Abraham Faustino; Medina-Torres, Luis; Calderas, Fausto; Gracia-Mora, Jesus; Bernad-Bernad, MaJosefa

2016-08-01

The influence of closantel on the rheological and physicochemical properties (particle size and by UV-Vis absorption spectroscopy) of PVA aqueous solutions is studied here. About 1% PVA aqueous solutions were prepared by varying the closantel content. The increase of closantel content led to a reduction in the particle size of final solutions. All the solutions were buffered at pH 7.4 and exhibited shear-thinning behavior. Furthermore, in oscillatory flow, a "solid-like" type behavior was observed for the sample containing 30 μg/mL closantel. Indicating a strong interaction between the dispersed and continuous phases and evidencing an interconnected network between the nanoparticle and PVA, this sample also showed the highest shear viscosity and higher shear thinning slope, indicating a more intrincate structure disrupted by shear. In conclusion, PVA interacts with closantel in aqueous solution and the critical concentration for closantel encapsulation by PVA was about 30 μg/mL; above this concentration, the average particle size decreased notoriously which was associated to closantel interacting with the surface of the PVA aggregates and thus avoiding to some extent direct polymer-polymer interaction.

Evaluation of the stability of uranyl peroxo-carbonato complex ions in carbonate media at different temperatures.

PubMed

Kim, Kwang-Wook; Lee, Keun-Young; Chung, Dong-Yong; Lee, Eil-Hee; Moon, Jei-Kwon; Shin, Dong-Woo

2012-09-30

This work studied the stability of peroxide in uranyl peroxo carbonato complex ions in a carbonate solution with hydrogen peroxide using absorption and Raman spectroscopies, and evaluated the temperature dependence of the decomposition characteristics of uranyl peroxo carbonato complex ions in the solution. The uranyl peroxo carbonato complex ions self-decomposed more rapidly into uranyl tris-carbonato complex ions in higher temperature carbonate solutions. The concentration of peroxide in the solution without free hydrogen peroxide represents the concentration of uranyl peroxo carbonato complex ions in a mixture of uranyl peroxo carbonato complex and uranyl tris-carbonato complex ions. The self-decomposition of the uranyl peroxo carbonato complex ions was a first order reaction, and its activation energy was evaluated to be 7.144×10(3) J mol(-1). The precipitation of sodium uranium oxide hydroxide occurred when the amount of uranyl tris-carbonato complex ions generated from the decomposition of the uranyl peroxo carbonato complex ions exceeded the solubility of uranyl tris-carbonato ions in the solution at the solution temperature. Copyright © 2012 Elsevier B.V. All rights reserved.

Molecular Dynamics Simulation of Surface Tension of NaCl Aqueous Solution at 298.15K: from Diluted to Highly Supersaturated Concentrations

NASA Astrophysics Data System (ADS)

Wang, Xiaoxiang; Chen, Chuchu; Poeschl, Ulirch; Su, Hang; Cheng, Yafang

2017-04-01

Sodium chloride (NaCl) is one of the key components of atmospheric aerosol particles. Concentration-depend surface tension of aqueous NaCl solution is essential to determine the equilibrium between droplet NaCl solution and water vapor, which is important in regards to aerosol-cloud interaction and aerosol climate effects. Although supersaturated NaCl droplets can be widely found under atmospheric conditions, the experimental determined concentration dependency of surface tension is limited up to the saturated concentration range due to technical difficulties, i.e., heterogeneous nucleation since nearly all surface tension measurement techniques requires contact of the sensor and solution surface. In this study, the surface tension of NaCl aqueous solution with solute mass fraction from 0 to 1 was calculated using molecular dynamics (MD) simulation. The surface tension increases monotonically and near linearly when mass fraction of NaCl (xNaCl) is lower than 0.265 (saturation point), which follows theoretical predictions (e.g., E-AIM, SP parameterization, and PK parameterization). Once entering into the supersaturated concentration range, the calculated surface tension starts to deviate from the near-linear extrapolation and adopts a slightly higher increasing rate until xNaCl of 0.35. We found that these two increasing phases (xNaCl 0.35) is mainly driven by the increase of excessive surface enthalpy when the solution becomes concentrated. After that, the surface tension remains almost unchanged until xNaCl of 0.52. This phenomenon is supported by the results from experiment based Differential Koehler Analyses. The stable surface tension in this concentration range is attributed to a simultaneous change of surface excess enthalpy and entropy at similar degree. When the NaCl solution is getting more concentrated than xNaCl of 0.52, the simulated surface tension regains an even faster growing momentum and shows the tendency of ultimately approaching the surface tension of molten NaCl at 298.15 K ( 148.4 mN/m by MD simulation). Energetic analyses imply that this fast increase is primarily still an excessive surface enthalpy-driven process, although concurrent fluctuation of excessive surface entropy is also expected but in a much smaller scale. Our results unfold the global landscape of concentration dependence of aqueous NaCl solution and its driven forces: a water surface tension dominated regime (xNaCl from 0 to 0.35), a transition regime (xNaCl from 0.35 to 0.52) and a molten NaCl surface tension dominated regime (xNaCl beyond 0.52).

Impact of long-term organic residue recycling in agriculture on soil solution composition and trace metal leaching in soils.

PubMed

Cambier, Philippe; Pot, Valérie; Mercier, Vincent; Michaud, Aurélia; Benoit, Pierre; Revallier, Agathe; Houot, Sabine

2014-11-15

Recycling composted organic residues in agriculture can reduce the need of mineral fertilizers and improve the physicochemical and biological properties of cultivated soils. However, some trace elements may accumulate in soils following repeated applications and impact other compartments of the agrosystems. This study aims at evaluating the long-term impact of such practices on the composition of soil leaching water, especially on trace metal concentrations. The field experiment QualiAgro started in 1998 on typical loess Luvisol of the Paris Basin, with a maize-wheat crop succession and five modalities: spreading of three different urban waste composts, farmyard manure (FYM), and no organic amendment (CTR). Inputs of trace metals have been close to regulatory limits, but supplies of organic matter and nitrogen overpassed common practices. Soil solutions were collected from wick lysimeters at 45 and 100 cm in one plot for each modality, during two drainage periods after the last spreading. Despite wide temporal variations, a significant effect of treatments on major solutes appears at 45 cm: DOC, Ca, K, Mg, Na, nitrate, sulphate and chloride concentrations were higher in most amended plots compared to CTR. Cu concentrations were also significantly higher in leachates of amended plots compared to CTR, whereas no clear effect emerged for Zn. The influence of amendments on solute concentrations appeared weaker at 1 m than at 45 cm, but still significant and positive for major anions and DOC. Average concentrations of Cu and Zn at 1m depth lied in the ranges [2.5; 3.8] and [2.5; 10.5 μg/L], respectively, with values slightly higher for plots amended with sewage sludge compost or FYM than for CTR. However, leaching of both metals was less than 1% of their respective inputs through organic amendments. For Cd, most values were <0.05 μg/L. So, metals added through spreading of compost or manure during 14 years may have increased metal concentrations in leachates of amended plots, in spite of increased soil organic matter, factor of metal retention. Indeed, DOC, also increased by amendments, favours the mobility of Cu; whereas pH variations, depending on treatments, influence negatively the solubility of Zn. Generic adsorption functions of these variables partly explain the variations of trace metal concentrations and helped to unravel the numerous processes induced by regular amendments with organic waste products. Copyright © 2014 Elsevier B.V. All rights reserved.

Japanese Papilio butterflies puddle using Na+ detected by contact chemosensilla in the proboscis.

PubMed

Inoue, Takashi A; Hata, Tamako; Asaoka, Kiyoshi; Ito, Tetsuo; Niihara, Kinuko; Hagiya, Hiroshi; Yokohari, Fumio

2012-12-01

Many butterflies acquire nutrients from non-nectar sources such as puddles. To better understand how male Papilio butterflies identify suitable sites for puddling, we used behavioral and electrophysiological methods to examine the responses of Japanese Papilio butterflies to Na(+), K(+), Ca(2+), and Mg(2+). Based on behavioral analyses, these butterflies preferred a 10-mM Na(+) solution to K(+), Ca(2+), and Mg(2+) solutions of the same concentration and among a tested range of 1 mM to 1 M NaCl. We also measured the ion concentrations of solutions sampled from puddling sites in the field. Na(+) concentrations of the samples were up to 6 mM, slightly lower than that preferred by butterflies in the behavioral experiments. Butterflies that sipped the 10 mM Na(+) solution from the experimental trays did not continue to puddle on the ground. Additionally, butterflies puddled at sites where the concentrations of K(+), Ca(2+), and/or Mg(2+) were higher than that of Na(+). This suggests that K(+), Ca(2+), and Mg(2+) do not interfere with the detection of Na(+) by the Papilio butterfly. Using an electrophysiological method, tip recordings, receptor neurons in contact chemosensilla inside the proboscis evoked regularly firing impulses to 1, 10, and 100 mM NaCl solutions but not to CaCl(2) or MgCl(2). The dose-response patterns to the NaCl solutions were different among the neurons, which were classified into three types. These results showed that Japanese Papilio butterflies puddle using Na(+) detected by the contact chemosensilla in the proboscis, which measure its concentration.

Pharmacokinetics of 2 Formulations of Transdermal Fentanyl in Cynomolgus Macaques (Macaca fascicularis)

PubMed Central

Carlson, Amy M; Kelly, Richard; Fetterer, David P; Rico, Pedro J; Bailey, Emily J

2016-01-01

Fentanyl is a μ-opioid agonist that often is used as the analgesic component for balanced anesthesia in both human and veterinary patients. Minimal information has been published regarding appropriate dosing, and the pharmacokinetics of fentanyl are unknown in NHP. The pharmacokinetic properties of 2 transdermal fentanyl delivery methods, a solution (2.6 and 1.95 mg/kg) and a patch (25 µg/h), were determined when applied topically to the dorsal scapular area of cynomolgus macaques (Macaca fascicularis). Serum fentanyl concentrations were analyzed by using liquid chromatography–mass spectrometry. Compared with the patch, the transdermal fentanyl solution generated higher drug concentrations over longer time. Adverse reactions occurred in the macaques that received the transdermal fentanyl solution at 2.6 mg/kg. Both preparations showed significant interanimal variability in the maximal serum drug levels, time to achieve maximal fentanyl levels, elimination half-life, and AUC values. Both the maximal concentration and the time at which this concentration occurred were increased in macaques compared with most other species after application of the transdermal fentanyl patch and compared with dogs after application of the transdermal fentanyl solution. The pharmacokinetic properties of transdermal fentanyl in macaques are markedly different from those in other veterinary species and preclude its use as a long-acting analgesic drug in NHP. PMID:27423151

Acute toxicity and inactivation tests of CO2 on invertebrates in drinking water treatment systems.

PubMed

Yin, Wen-Chao; Zhang, Jin-Song; Liu, Li-Jun; Zhao, Jian-Shu; Li, Tuo

2011-01-01

In addition to the esthetic problem caused by invertebrates, researchers are recently starting to be more aware of their potential importance in terms of public health. However, the inactivation methods of invertebrates which could proliferate in drinking water treatment systems are not well developed. The objective of this study is to assess the acute toxicity and inactivation effects of CO2 on familiar invertebrates in water treatment processes. The results of this study revealed that CO2 has a definite toxicity to familiar invertebrates. The values of 24-h LC50 (median lethal concentration) were calculated for each test with six groups of invertebrates. The toxicity of CO2 was higher with increasing concentrations in solution but was lower with the increase in size of the invertebrates. Above the concentration of 1,000 mg/L for the CO2 solution, the 100% inactivation time of all the invertebrates was less than 5 s, and in 15 min, the inactivation ratio showed a gradient descent with a decline in concentration. As seen for Mesocyclops thermocyclopoides, by dosing with a sodium bicarbonate solution first and adding a dilute hydrochloric acid solution 5 min later, it is possible to obtain a satisfactory inactivation effect in the GAC (granular activated carbon) filters.

Optimization of Photooxidative Removal of Phenazopyridine from Water

NASA Astrophysics Data System (ADS)

Saeid, Soudabeh; Behnajady, Mohammad A.; Tolvanen, Pasi; Salmi, Tapio

2018-05-01

The photooxidative removal of analgesic pharmaceutical compound phenazopyridine (PhP) from aqueous solutions by UV/H2O2 system with a re-circulated photoreactor was investigated. Response surface methodology (RSM) was employed to optimize the effect of operational parameters on the photooxidative removal efficiency. The investigated variables were: the initial PhP and H2O2 concentrations, irradiation time, volume of solution and pH. The analysis of variance (ANOVA) of quadratic model demonstrated that the described model was highly significant. The predicted values of the photooxidative removal efficiency were found to be in a fair agreement with experimental values ( R 2 = 0.9832, adjusted R 2 = 0.9716). The model predicted that the optimal reaction conditions for a maximum removal of PhP (>98%) were: initial PhP concentration less than 23 mg L-1, initial concentration of H2O2 higher than 470 mg L-1, solution volume less than 500 mL, pH close to 2 and irradiation time longer than 6 min.

Removal of ammonium from aqueous solutions with volcanic tuff.

PubMed

Marañón, E; Ulmanu, M; Fernández, Y; Anger, I; Castrillón, L

2006-10-11

This paper presents kinetic and equilibrium data concerning ammonium ion uptake from aqueous solutions using Romanian volcanic tuff. The influence of contact time, pH, ammonium concentration, presence of other cations and anion species is discussed. Equilibrium isotherms adequately fit the Langmuir and Freundlich models. The results showed a contact time of 3h to be sufficient to reach equilibrium and pH of 7 to be the optimum value. Adsorption capacities of 19 mg NH(4)(+)/g were obtained in multicomponent solutions (containing NH(4)(+), Zn(2+), Cd(2+), Ca(2+), Na(2+)). The presence of Zn and Cd at low concentrations did not decrease the ammonium adsorption capacity. Comparison of Romanian volcanic tuff with synthetic zeolites used for ammonium removal (5A, 13X and ZSM-5) was carried out. The removal efficiciency of ammonium by volcanic tuff were similar to those of zeolites 5A and 13X at low initial ammonium concentration, and much higher than those of zeolite ZSM-5.

Halide Ions Effects on Surface Excess of Long Chain Ionic Liquids Water Solutions

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

Wang, Wenjie; Sung, Woongmo; Ao, Mingqi

2013-10-07

The interfacial structure and composition of water solutions with alkylimidazolium ionic liquids varying in their halide anions ([C12mim][X], X = Cl and I) were investigated by X-ray near-total-reflection fluorescence spectroscopy and X-ray reflectivity measurements. We demonstrate that X-ray fluorescence and reflectivity techniques provide a more direct measurement of surface adsorption. Furthermore, we show that for [C12mim][Cl] and [C12mim][I] solutions with mixed inorganic salts (NaI, NaCl), I– ions replace Cl– above the critical micelle concentration (CMC) of [C12mim][Cl] at much lower concentrations of NaI, whereas NaCl concentrations a hundred times higher than the CMC of [C12mim][I] only partially replace the I–more » at the interface. Our surface-sensitive X-ray diffraction and spectroscopy provide two independent tools to directly determine the surface adsorption of ionic surfactants and the interfacial composition of the surface films.« less

X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell.

PubMed

Ketenoglu, Didem; Spiekermann, Georg; Harder, Manuel; Oz, Erdinc; Koz, Cevriye; Yagci, Mehmet C; Yilmaz, Eda; Yin, Zhong; Sahle, Christoph J; Detlefs, Blanka; Yavaş, Hasan

2018-03-01

The effects of varying LiPF 6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate-dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li + ion concentration in the solvent manifests itself as a blue-shift of both the π* feature in the carbon edge and the carbonyl π* feature in the oxygen edge. While these oxygen K-edge results agree with previous soft X-ray absorption studies on LiBF 4 salt concentration in propylene carbonate, carbon K-edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions.

Direct Analysis of Proteins from Solutions with High Salt Concentration Using Laser Electrospray Mass Spectrometry

NASA Astrophysics Data System (ADS)

Karki, Santosh; Shi, Fengjian; Archer, Jieutonne J.; Sistani, Habiballah; Levis, Robert J.

2018-05-01

The detection of lysozyme, or a mixture of lysozyme, cytochrome c, and myoglobin, from solutions with varying salt concentrations (0.1 to 250 mM NaCl) is compared using laser electrospray mass spectrometry (LEMS) and electrospray ionization-mass spectrometry (ESI-MS). Protonated protein peaks were observed up to a concentration of 250 mM NaCl in the case of LEMS. In the case of ESI-MS, a protein solution with salt concentration > 0.5 mM resulted in predominantly salt-adducted features, with suppression of the protonated protein ions. The constituents in the mixture of proteins were assignable up to 250 mM NaCl for LEMS and were not assignable above a NaCl concentration of 0.5 mM for ESI. The average sodium adducts (< n >) bound to the 7+ charge state of lysozyme for LEMS measurements from salt concentrations of 2.5, 25, 50, and 100 mM NaCl are 1.71, 5.23, 5.26, and 5.11, respectively. The conventional electrospray measurements for lysozyme solution containing salt concentrations of 0.1, 1, 2, and 5 mM NaCl resulted in < n > of 2.65, 6.44, 7.57, and 8.48, respectively. LEMS displays an approximately two orders of magnitude higher salt tolerance in comparison with conventional ESI-MS. The non-equilibrium partitioning of proteins on the surface of the charged droplets is proposed as the mechanism for the high salt tolerance phenomena observed in the LEMS measurements. [Figure not available: see fulltext.

Direct Analysis of Proteins from Solutions with High Salt Concentration Using Laser Electrospray Mass Spectrometry

NASA Astrophysics Data System (ADS)

Karki, Santosh; Shi, Fengjian; Archer, Jieutonne J.; Sistani, Habiballah; Levis, Robert J.

2018-03-01

The detection of lysozyme, or a mixture of lysozyme, cytochrome c, and myoglobin, from solutions with varying salt concentrations (0.1 to 250 mM NaCl) is compared using laser electrospray mass spectrometry (LEMS) and electrospray ionization-mass spectrometry (ESI-MS). Protonated protein peaks were observed up to a concentration of 250 mM NaCl in the case of LEMS. In the case of ESI-MS, a protein solution with salt concentration > 0.5 mM resulted in predominantly salt-adducted features, with suppression of the protonated protein ions. The constituents in the mixture of proteins were assignable up to 250 mM NaCl for LEMS and were not assignable above a NaCl concentration of 0.5 mM for ESI. The average sodium adducts (< n >) bound to the 7+ charge state of lysozyme for LEMS measurements from salt concentrations of 2.5, 25, 50, and 100 mM NaCl are 1.71, 5.23, 5.26, and 5.11, respectively. The conventional electrospray measurements for lysozyme solution containing salt concentrations of 0.1, 1, 2, and 5 mM NaCl resulted in < n > of 2.65, 6.44, 7.57, and 8.48, respectively. LEMS displays an approximately two orders of magnitude higher salt tolerance in comparison with conventional ESI-MS. The non-equilibrium partitioning of proteins on the surface of the charged droplets is proposed as the mechanism for the high salt tolerance phenomena observed in the LEMS measurements. [Figure not available: see fulltext.

Adsorption of poly(vinyl alcohol) from water to a hydrophobic surface: effects of molecular weight, degree of hydrolysis, salt, and temperature.

PubMed

Kozlov, Mikhail; McCarthy, Thomas J

2004-10-12

The adsorption of poly(vinyl alcohol) (PVOH) from aqueous solutions to a silicon-supported fluoroalkyl monolayer is described. Thickness, wettability, and roughness of adsorbed films are studied as a function of polymer molecular weight, degree of hydrolysis (from the precursor, poly(vinyl acetate)), polymer concentration, salt type and concentration, and temperature. The data suggest a two-stage process for adsorption of the polymer: physisorption due to a hydrophobic effect (decrease in interfacial free energy) and subsequent stabilization of the adsorbed layer due to crystallization of the polymer. Adsorption of lower-molecular-weight polymers results in thicker films than those prepared with a higher molecular weight; this is ascribed to better crystallization of more mobile short chains. Higher contents of unhydrolyzed acetate groups on the poly(vinyl alcohol) chain lead to thicker adsorbed films. Residual acetate groups partition to the outermost surface of the films and determine wettability. Salts, including sodium chloride and sodium sulfate, promote adsorption, which results in thicker films; at the same time, their presence over a wide concentration range leads to formation of rough coatings. Sodium thiocyanate has little effect on PVOH adsorption, only slightly reducing the thickness in a 2 M salt solution. Increased temperature promotes adsorption in the presence of salt, but has little effect on salt-free solutions. Evidently, higher temperatures favor adsorption but cause crystallization to be less thermodynamically favorable. These competing effects result in the smoothest coatings being formed in an intermediate temperature range. Copyright 2004 American Chemical Society

Characterization of amine-functionalized electrode for aqueous carbon dioxide (CO2) direct detection

NASA Astrophysics Data System (ADS)

Sato, Hiroshi

2017-03-01

In this study, fabrication of amino groups and ferrocenes co-modified sensor electrode and electrochemical detection of carbon dioxide (CO2) in the saline solution is reported. Electrochemical detection of CO2 was carried out using cyclic voltammetry in saline solution containing sodium bicarbonate as CO2 source. Oxidation and reduction peak current intensities computed from cyclic voltammograms varied as a function of concentration of CO2 molecules. The calibration curve was obtained by plotting oxidation peak current intensities as a function of CO2 concentration. The sensor electrode prepared in this study can estimate the differences between concentrations of CO2 in normal seawater up to 10 times higher. Furthermore, the surface analysis was performed to clarify the CO2 detection mechanism.

PHYSICOCHEMICAL PROPERTIES OF THE PROTEOLYTIC ENZYME FROM THE LATEX OF THE MILKWEED, ASCLEPIAS SPECIOSA TORR. SOME COMPARISONS WITH OTHER PROTEASES

PubMed Central

Winnick, Theodore; Davis, Alva R.; Greenberg, David M.

1940-01-01

1. The kinetics of milk clotting by asclepain, the protease of Asclepias speciosa, were investigated. At higher concentrations of enzyme, the clotting time was inversely proportional to the enzyme concentration. 2. The digestion of casein and hemoglobin in 6.6 M urea by asclepain follows the second order reaction rate. The rate was roughly second order for casein in water. 3. Evaluation of the nature of the enzyme-substrate intermediate indicates that one molecule of asclepain combines with one molecule of casein or hemoglobin in urea solution. 4. Inhibition by the reaction products was deduced from the fact that the digestion velocity of hemoglobin in urea solution varied with the asclepain concentration in agreement with the Schütz-Borissov rule. PMID:19873155

Questa baseline and pre-mining ground-water quality investigation. 20. Water chemistry of the Red River and selected seeps, tributaries, and precipitation, Taos County, New Mexico, 2000-2004

USGS Publications Warehouse

Verplanck, P.L.; McCleskey, R. Blaine; Nordstrom, D. Kirk

2006-01-01

As part of a multi-year project to infer the pre-mining ground-water quality at Molycorp's Questa mine site, surface-water samples of the Red River, some of its tributaries, seeps, and snow samples were collected for analysis of inorganic solutes and of water and sulfate stable isotopes in selected samples. The primary aim of this study was to document diel, storm event, and seasonal variations in water chemistry for the Red River and similar variations in water chemistry for Straight Creek, a natural analog site similar in topography, hydrology, and geology to the mine site for inferring pre-mining water-quality conditions. Red River water samples collected between 2000 and 2004 show that the largest variations in water chemistry occur during late summer rainstorms, often monsoonal in nature. Within hours, discharge of the Red River increased from 8 to 102 cubic feet per second and pH decreased from 7.80 to 4.83. The highest concentrations of metals (iron, aluminum, zinc, manganese) and sulfate also occur during such events. Low-pH and high-solute concentrations during rainstorm runoff are derived primarily from alteration 'scar' areas of naturally high mineralization combined with steep topography that exposes continually altered rock because erosion is too rapid for vegetative growth. The year 2002 was one of the driest on record, and Red River discharge reflected the low seasonal snow pack. No snowmelt peak appeared in the hydrograph record, and a late summer storm produced the highest flow for the year. Snowmelt was closer to normal during 2003 and demonstrated the dilution effect of snowmelt on water chemistry. Two diel sampling events were conducted for the Red River, one during low flow and the other during high flow, at two locations, at the Red River gaging station and just upstream from Molycorp's mill site. No discernible diel trends were observed except for dissolved zinc and manganese at the upstream site during low flow. Straight Creek drainage water was sampled periodically from 2001 to 2004 at the down stream end of surface drainage near the point at which it disappeared into the debris fan. This water has a minimal range in pH (2.7 to 3.2) but a substantial concentration range in many solutes; for example, sulfate concentrations varied from 525 to 2,660 mg/L. Many elements covary with sulfate suggesting that dilution is the primary control of the range in solute concentrations. A transect of water samples higher in the scar area were collected in October of 2003. They had a lower range in pH (2.44 to 3.05) and higher solute concentrations than those collected periodically from lower in the catchment. Water isotopes for the upper transect samples indicated slight evaporation, and in part, may account for the higher solute concentrations. Drainage waters also were collected from Hottentot, Junebug, Hansen, Little Hansen, and Goat Hill Gulch drainages. Most constituents from other scar drainage waters showed ranges of concentration similar to those of the Straight Creek waters. An exception was water collected from Goat Hill Gulch, which has some of the highest concentrations of any surface-water sample collected but also contained waste-rock leachates.

Removing adsorbed heavy metal ions from sand surfaces via applying interfacial properties of rhamnolipid.

PubMed

Haryanto, Bode; Chang, Chien-Hsiang

2015-01-01

In this study, the interfacial properties of biosurfactant rhamnolipid were investigated and were applied to remove adsorbed heavy metal ions from sand surfaces with flushing operations. The surface tension-lowering activity, micelle charge characteristic, and foaming ability of rhamnolipid were identified first. For rhamnolipid in water, the negatively charged characteristic of micelles or aggregates was confirmed and the foaming ability at concentrations higher than 40 mg/L was evaluated. By using the rhamnolipid solutions in a batch washing approach, the potential of applying the interfacial properties of rhamnolipid to remove adsorbed copper ions from sand surfaces was then demonstrated. In rhamnolipid solution flushing operations for sand-packed medium, higher efficiency was found for the removal of adsorbed copper ions with residual type than with inner-sphere interaction type, implying the important role of interaction type between the copper ion and the sand surface in the removal efficiency. In addition, the channeling effect of rhamnolipid solution flow in the sand-packed medium was clearly observed in the solution flushing operations and was responsible for the low removal efficiency with low contact areas between solution and sand. By using rhamnolipid solution with foam to flush the sand-packed medium, one could find that the channeling effect of the solution flow was reduced and became less pronounced with the increase in the rhamnolipid concentration, or with the enhanced foaming ability. With the reduced channeling effect in the flushing operations, the removal efficiency for adsorbed copper ions was significantly improved. The results suggested that the foam-enhanced rhamnolipid solution flushing operation was efficient in terms of surfactant usage and operation time.

An ex vivo human aqueous humor-concentration comparison of two commercial bromfenac formulations

PubMed Central

Walters, Thomas R; Smyth-Medina, Robert J; Cockrum, Paul C

2018-01-01

Purpose The purpose of this study was to quantify the concentration of bromfenac in the aqueous humor utilizing high-performance liquid chromatography mass spectrometry between two commercial nonsteroidal anti-inflammatory drugs, using aqueous humor concentrations to characterize pharmacokinetic proportional differences between 0.075% bromfenac ophthalmic solution in DuraSite (BromSite®) and 0.09% bromfenac ophthalmic solution (Bromday®). Methods In this multicenter, randomized, double-masked, two-arm, parallel-group, comparative, Phase II clinical trial, subjects were assigned to receive bromfenac in DuraSite or bromfenac ophthalmic solution in a 1:1 ratio. One drop of the masked test article was instilled into the study eye once a day for 2 days prior to and 3 hours prior (last instillation) to the subject’s cataract surgery. Aqueous humor samples were collected upon initial cataract incision for analysis of bromfenac levels. The primary end point was aqueous humor concentration of bromfenac at Day 3, at the initiation of cataract surgery. Aqueous humor samples were collected and analyzed for bromfenac levels. Results A total of 60 subjects completed the study, 30 in each group. The mean bromfenac aqueous humor concentration in subjects who received bromfenac in DuraSite was more than twice (49.33±41.87 ng/mL, P=0.004) that of subjects who received bromfenac ophthalmic solution (23.65±16.31 ng/mL) after three doses. Conclusion Mean bromfenac aqueous humor concentration in subjects receiving the DuraSite-containing bromfenac in DuraSite (0.075%) was significantly higher compared to subjects receiving bromfenac ophthalmic solution (0.09%) after 3 days of dosing. PMID:29849449

Cast Stone Formulation At Higher Sodium Concentrations

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

Fox, K. M.; Roberts, K. A.; Edwards, T. B.

2013-09-17

A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, includingmore » production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leach indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the limited range of the factors in the test matrix hindered the identification of individual component effects. Future work should involve broader factor ranges to identify the roles played by each of the components in the mix via thermal analyses, analytical microscopy, and characterization of phase formation.« less

Cast Stone Formulation At Higher Sodium Concentrations

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

Fox, K. M.; Edwards, T. A.; Roberts, K. B.

2013-10-02

A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, includingmore » production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leach indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the limited range of the factors in the test matrix hindered the identification of individual component effects. Future work should involve broader factor ranges to identify the roles played by each of the components in the mix via thermal analyses, analytical microscopy, and characterization of phase formation.« less

Cast Stone Formulation At Higher Sodium Concentrations

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

Fox, K. M.; Roberts, K. A.; Edwards, T. B.

2014-02-28

A low temperature waste form known as Cast Stone is being considered to provide supplemental Low Activity Waste (LAW) immobilization capacity for the Hanford site. Formulation of Cast Stone at high sodium concentrations is of interest since a significant reduction in the necessary volume of Cast Stone and subsequent disposal costs could be achieved if an acceptable waste form can be produced with a high sodium molarity salt solution combined with a high water to premix (or dry blend) ratio. The objectives of this study were to evaluate the factors involved with increasing the sodium concentration in Cast Stone, includingmore » production and performance properties and the retention and release of specific components of interest. Three factors were identified for the experimental matrix: the concentration of sodium in the simulated salt solution, the water to premix ratio, and the blast furnace slag portion of the premix. The salt solution simulants used in this study were formulated to represent the overall average waste composition. The cement, blast furnace slag, and fly ash were sourced from a supplier in the Hanford area in order to be representative. The test mixes were prepared in the laboratory and fresh properties were measured. Fresh density increased with increasing sodium molarity and with decreasing water to premix ratio, as expected given the individual densities of these components. Rheology measurements showed that all of the test mixes produced very fluid slurries. The fresh density and rheology data are of potential value in designing a future Cast Stone production facility. Standing water and density gradient testing showed that settling is not of particular concern for the high sodium compositions studied. Heat of hydration measurements may provide some insight into the reactions that occur within the test mixes, which may in turn be related to the properties and performance of the waste form. These measurements showed that increased sodium concentration in the salt solution reduced the time to peak heat flow, and reducing the amount of slag in the premix increased the time to peak heat flow. These observations may help to describe some of the cured properties of the samples, in particular the differences in compressive strength observed after 28 and 90 days of curing. Samples were cured for at least 28 days at ambient temperature in the laboratory prior to cured properties analyses. The low activity waste form for disposal at the Hanford Site is required to have a compressive strength of at least 500 psi. After 28 days of curing, several of the test mixes had mean compressive strengths that were below the 500 psi requirement. Higher sodium concentrations and higher water to premix ratios led to reduced compressive strength. Higher fly ash concentrations decreased the compressive strength after 28 days of curing. This may be explained in that the cementitious phases matured more quickly in the mixes with higher concentrations of slag, as evidenced by the data for the time to peak heat generation. All of the test mixes exhibited higher mean compressive strengths after 90 days of curing, with only one composition having a mean compressive strength of less than 500 psi. Leachability indices were determined for the test mixes for contaminants of interest. The leaching performance of the mixes evaluated in this study was not particularly sensitive to the factors used in the experimental design. This may be beneficial in demonstrating that the performance of the waste form is robust with respect to changes in the mix composition. The results of this study demonstrate the potential to achieve significantly higher waste loadings in Cast Stone and other low temperature, cementitious waste forms. Additional work is needed to elucidate the hydration mechanisms occurring in Cast Stone formulated with highly concentrated salt solutions since these reactions are responsible for determining the performance of the cured waste form. The thermal analyses completed in this study provide some preliminary insight, although the limited range of the factors in the test matrix hindered the identification of individual component effects. Future work should involve broader factor ranges to identify the roles played by each of the components in the mix via thermal analyses, analytical microscopy, and characterization of phase formation.« less

Twenty-year inter-annual trends and seasonal variations in precipitation and stream water chemistry at the Bear Brook Watershed in Maine, USA.

PubMed

Navrátil, Tomas; Norton, Stephen A; Fernandez, Ivan J; Nelson, Sarah J

2010-12-01

Mean annual concentration of SO4(-2) in wet-only deposition has decreased between 1988 and 2006 at the paired watershed study at Bear Brook Watershed in Maine, USA (BBWM) due to substantially decreased emissions of SO(2). Emissions of NO(x) have not changed substantially, but deposition has declined slightly at BBWM. Base cations, NH4+, and Cl(-) concentrations were largely unchanged, with small irregular changes of <1 μeq L(-1) per year from 1988 to 2006. Precipitation chemistry, hydrology, vegetation, and temperature drive seasonal stream chemistry. Low flow periods were typical in June-October, with relatively greater contributions of deeper flow solutions with higher pH; higher concentrations of acid-neutralizing capacity, Si, and non-marine Na; and low concentrations of inorganic Al. High flow periods during November-May were typically dominated by solutions following shallow flow paths, which were characterized by lower pH and higher Al and DOC concentrations. Biological activity strongly controlled NO3- and K(+). They were depressed during the growing season and elevated in the fall. Since 1987, East Bear Brook (EB), the reference stream, has been slowly responding to reduced but still elevated acid deposition. Calcium and Mg have declined fairly steadily and faster than SO4(-2), with consequent acidification (lower pH and higher inorganic Al). Eighteen years of experimental treatment with (NH(4))(2)SO(4) enhanced acidification of West Bear Brook's (WB) watershed. Despite the manipulation, NH4+ concentration remained below detection limits at WB, while leaching of NO3- increased. The seasonal pattern for NO3- concentrations in WB, however, remained similar to EB. Mean monthly concentrations of SO4(-2) have increased in WB since 1989, initially only during periods of high flow, but gradually also during base flow. Increases in mean monthly concentrations of Ca(2+), Mg(2+), and K(+) due to the manipulation occurred from 1989 until about 1995, during the depletion of base cations in shallow flow paths in WB. Progressive depletion of Ca and Mg at greater soil depth occurred, causing stream concentrations to decline to pre-manipulation values. Mean monthly Si concentrations did not change in EB or WB, suggesting that the manipulation had no effect on mineral weathering rates. DOC concentrations in both streams did not exhibit inter- or intra-annual trends.

Spinning-disk generation and drying of monodisperse solid aerosols with output concentrations sufficient for single-breath inhalation studies.

PubMed

Byron, P R; Hickey, A J

1987-01-01

The air-driven spinning-disk aerosol generator was modified to allow the production of monodisperse dry spherical aerosols of disodium fluorescein (as model solute) in high output concentrations. Output concentrations were determined by filtration. Optical and aerodynamic size distributions were determined microscopically (after electrostatic precipitation) and by cascade impaction. The generator housing allowed the entrainment of 25-microns primary aqueous solution droplets in a 10-L X min-1 downward flow of dry, filtered air. Internal equipment surfaces were machined flush and polished to minimize aerosol losses. Primary droplets were dried within a stainless steel pipe encased in a tube furnace. Water vapor was removed by diffusion drying. Disk-driven air, satellite droplets, and additional dilution air were vented to waste without using a vacuum. Generator yields were increased by reducing the size of the satellite droplet extraction gap. Aerosols were generated reproducibly by delivering aqueous solutions at a rate of 0.2 mL X min-1 to the center of the disk and spinning at 1000 rps. Dry aerosols, with mass median aerodynamic diameters of 2, 4.9, and 9 microns, were produced in concentrations of 0.89, 5.48, and 54.6 micrograms X L-1 from aqueous solutions containing 0.0374, 0.584, and 3.4% solute by weight. Geometric standard deviations were less than 1.2 in all cases. Concentrations are several times higher than others in the literature and are suitable for single-breath inhalation studies of therapeutic aerosol deposition and effect.

Method for the preparation of inorganic single crystal and polycrystalline electronic materials

NASA Technical Reports Server (NTRS)

Groves, W. O. (Inventor)

1969-01-01

Large area, semiconductor crystals selected from group 3-5 compounds and alloys are provided for semiconductor device fabrication by the use of a selective etching operation which completely removes the substrate on which the desired crystal was deposited. The substrate, selected from the same group as the single crystal, has a higher solution rate than the epitaxial single crystal which is essentially unaffected by the etching solution. The preparation of gallium phosphide single crystals using a gallium arsenide substrate and a concentrated nitric acid etching solution is described.

Iron, Manganese and Copper Release from Synthetic Hydroxyapatite

NASA Technical Reports Server (NTRS)

Sutter, B.; Hossner, L. R.; Ming, Douglas W.

1999-01-01

Kinetic stir-flow dissolution experiments were performed on iron- (Fe-SHA), manganese- (Mn-SHA), and copper- (Cu-SHA) containing synthetic hydroxyapatites. Solution treatments consisted of de-ionized water, citric acid and DTPA. Initially, Mn concentrations were higher than Cu concentrations and Fe concentrations were the lowest in all treatments. At later times Mn and Cu concentrations dropped in the DTPA treatment while Fe rose to the concentration similar to Mn and Cu. At all times, metal release concentrations in the water and citric acid treatments followed the trend of Mn>Cu>Fe. Rietveld analysis of x-ray diffraction data and ^31P NMR indicated that the metals substituted for Ca in the SHA structure. However, EPR data suggested that a metal (hydr)oxide phase existed either on the SHA surface or between the SHA crystallites. The metal concentration trend of Mn>Cu>Fe suggested that the initial solution metal concentrations are dependent on the dissolution of (hydr)oxides from SHA surfaces or between SHA crystallites. Similar metal concentrations at later times in the DTPA experiments suggests that metal concentrations were controlled by the release of Mn, Cu, or Fe from the SHA structure.

An Alternative Hypothesis for How Microgravity Improves Macromolecular Crystal Quality

NASA Technical Reports Server (NTRS)

Pusey, Marc

2003-01-01

There is a substantial body of experimental evidence, from this and other laboratories, that strongly suggests that for many proteins crystal nucleation and growth is by addition of associated species that are preformed by reversible concentration-driven self association processes in the bulk solution. We have developed a self-association model for the crystal nucleation and growth of the protein chicken egg lysozyme. The model accounts for the obtained crystal symmetry, explains the observed surface structures, and shows the importance of the symmetry obtained by self-association in solution to the process as a whole. This model also offers a possible mechanism for fluid flow effects on the growth process and how microgravity may affect it. While a single lysozyme molecule is relatively small an octamer in the 43 helix configuration (the proposed average sized growth unit) would have a M.W. approx. 115,000 and dimensions of 5.6 x 5.6 x 7.6 nm. Direct AFM measurements of growth unit incorporation indicate that units as wide as 11.2 nm and as long as 11.4 nm (a 24-mer) commonly attach to the crystal. AFM results from Weichmann et al. (Ultramicroscopy 86, 159-166, 2001) suggest that associated species of up to 40-mers in size add to the (101) faces. These measurements reflect the sizes of units that both added and desorbed from the crystal surface. The larger and less isotropic the associated species the more likely that it will be oriented to some degree in a flowing boundary layer, even at the low flow velocities measured about macromolecule crystals. On Earth, concentration gradient driven flow will maintain a high interfacial concentration, i.e., a high level (essentially that of the bulk solution) of solute association at the interface and higher growth rate. Higher growth rates mean an increased probability that misaligned growth units are trapped by subsequent growth layers before they can be desorbed and try again, or that the desorbing species is more likely to be smaller than the adsorbing species. In microgravity the extended diffusive boundary layer will lower the interfacial concentration. This results in a net dissociation of aggregated species that diffuse in from the bulk solution, i.e., smaller associated species, which are more likely able to make multiple attempts to correctly bind, yielding higher quality crystals.

Bipolar membrane electrodialysis for generation of hydrochloric acid and ammonia from simulated ammonium chloride wastewater.

PubMed

Li, Ya; Shi, Shaoyuan; Cao, Hongbin; Wu, Xinmin; Zhao, Zhijuan; Wang, Liying

2016-02-01

Simulated ammonium chloride wastewater was treated by a lab-scale bipolar membrane electrodialysis for the generation of HCl and NH3·H2O and desalination. The influence of initial concentration of NH4Cl, current density, salt solution volume, initial concentration of acid and base and membrane stack structure on the yields of HCl and NH3·H2O was investigated. The current efficiency and energy consumption were also examined under different conditions. The results showed that, at the current density of 48 mA/cm(2), the highest concentration of HCl and NH3·H2O with initial concentration of 110 g/L NH4Cl was 57.67 g/L and 45.85 g/L, respectively. Higher initial concentration of NH4Cl was favor to reduce unit energy consumption and increase current efficiency of the BMED system. The membrane stack voltage of BMED increased quickly under constant current when the concentration of NH4Cl contained in the solution of salt compartment was depleted below the "inflection point concentration" about 8000 mg/L. It means that the concentration of NH4Cl below 8000 mg/L was no longer suitable for BMED because of higher energy consumption. The HCl and NH3·H2O concentration increased more quickly following the increase of current density. When increasing the volume of NH4Cl, the concentration of HCl and NH3·H2O also increased. The high initial concentration of acid and base could improve the final concentration of them, while the growth rate was decreased. Compared with the BMED system with three compartments, the growth rate of HCl concentration with the two compartments was higher and its unit energy consumption was lower. It meant that the performance of the BMED system could be improved by optimizing operation conditions. The application feasibility of the generation of HCl and NH3·H2O and desalination of ammonium chloride wastewater by BMED was proved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synergistic Growth of Giant Wormlike Micelles in Ternary Mixed Surfactant Solutions: Effect of Octanoic Acid.

PubMed

Georgieva, Gergana S; Anachkov, Svetoslav E; Lieberwirth, Ingo; Koynov, Kaloian; Kralchevsky, Peter A

2016-12-06

The synergistic growth of giant wormlike micelles in ternary mixed solutions composed of an anionic surfactant (sodium laurylethersulfate, SLES), a zwitterionic surfactant (cocamidopropyl betaine, CAPB), and octanoic acid (HC8) is studied. Rheological data and their analysis in terms of Cole-Cole plots and micellar characteristic times are presented, and the micellar structures behind the observed rheological behavior are revealed by cryo-TEM micrographs. The surfactant composition is fixed near the maximal micelle size of the binary SLES + CAPB system, whereas the concentration of HC8 is varied. At a given HC8 concentration, the viscosity of the ternary micellar solutions exhibits a very high and sharp peak. Polarized-light optical microscopy indicates that all investigated solutions are isotropic rather than liquid-crystalline. The cryo-TEM imaging shows complex phase behavior: wormlike micelles to the left of the peak, giant entangled wormlike micelles at the peak, and long wormlike micelles coexisting with multiconnected micellar aggregates to the right of the peak. The formation of multiconnected micelles leads to a drop in viscosity at the higher concentrations. The results contribute to a better understanding of the structure-rheology relations in micellar surfactant solutions and could be useful for controlling the properties of formulations in personal-care and house-hold detergency.

Solvation of magnesium dication: molecular dynamics simulation and vibrational spectroscopic study of magnesium chloride in aqueous solutions.

PubMed

Callahan, Karen M; Casillas-Ituarte, Nadia N; Roeselová, Martina; Allen, Heather C; Tobias, Douglas J

2010-04-22

Magnesium dication plays many significant roles in biochemistry. While it is available to the environment from both ocean waters and mineral salts on land, its roles in environmental and atmospheric chemistry are still relatively unknown. Several pieces of experimental evidence suggest that contact ion pairing may not exist at ambient conditions in solutions of magnesium chloride up to saturation concentrations. This is not typical of most ions. There has been disagreement in the molecular dynamics literature concerning the existence of ion pairing in magnesium chloride solutions. Using a force field developed during this study, we show that contact ion pairing is not energetically favorable. Additionally, we present a concentration-dependent Raman spectroscopic study of the Mg-O(water) hexaaquo stretch that clearly supports the absence of ion pairing in MgCl(2) solutions, although a transition occurring in the spectrum between 0.06x and 0.09x suggests a change in solution structure. Finally, we compare experimental and calculated observables to validate our force field as well as two other commonly used magnesium force fields, and in the process show that ion pairing of magnesium clearly is not observed at higher concentrations in aqueous solutions of magnesium chloride, independent of the choice of magnesium force field, although some force fields give better agreement to experimental results than others.

Effects of the addition and aging of humic acid-based amendments on the solubility of Cd in soil solution and its accumulation in rice.

PubMed

Yu, Yao; Wan, Yanan; Camara, Aboubacar Younoussa; Li, Huafen

2018-04-01

Humic substances can reduce mobility and bio-accessibility of Cd in soil and therefore inhibit its uptake by rice, which is a major source of human Cd intake. Yet, the effects of aging humic substances are not fully understood. A rice pot experiment was conducted to evaluate the effects of humic acid-based amendments on the mobility of Cd in soil solution and its uptake by rice when amendments were freshly added or aged for 130 d. The results showed that the aged and the unaged amendments generally decreased Cd concentration in soil solution, but the effect declined with time. Unaged HA-K (humic-potassium) reduced Cd concentration by 88% for the first sampling, but this dropped to 46% for the last sampling, compared to that of the control. All amendments, whether aged or not, reduced the content of Cd in rice seedlings, as well as in mature plants. Aged and unaged woody peat reduced the Cd content in seedlings by 79% and in grains by 70%, respectively. Aging of amendments caused lower pH and higher Cd concentration in the soil solution for all amendments and accordingly, the Cd content in rice seedlings or each part of mature plants in the aged group was higher than that of the unaged group. The applied amendments might reduce the solubility of Cd through the alteration in soil pH, and thus inhibit the uptake of Cd by rice, but the effects diminished with aging. Copyright © 2018 Elsevier Ltd. All rights reserved.

Steady and dynamic shear rheological behavior of semi dilute Alyssum homolocarpum seed gum solutions: influence of concentration, temperature and heating-cooling rate.

PubMed

Alaeddini, Behzad; Koocheki, Arash; Mohammadzadeh Milani, Jafar; Razavi, Seyed Mohammad Ali; Ghanbarzadeh, Babak

2018-05-01

Alyssum homolocarpum seed gum (AHSG) solution exhibits high viscosity at low shear rates and has anionic features. However there is no information regarding the flow and dynamic properties of this gum in semi-dilute solutions. The present study aimed to investigate the dynamic and steady shear behavior of AHSG in the semi-dilute region. The viscosity profile demonestrated a shear thinning behavior at all temperatures and concentrations. An increase in the AHSG concentration was acompanied by an increase in the pseudoplasticity degree, whereas, by increasing the temperature, the pseudoplasticity of AHSG decreased. At low gum concentration, solutions had more viscosity dependence on temperature. The mechanical spectra obtained from the frequency sweep experiment demonstrated viscoelastic properties for gum solutions. AHSG solutions showed typical weak gel-like behavior, revealing G' greater than G' within the experimental range of frequency (Hz), with slight frequency dependency. The influence of temperature on viscoelastic properties of AHSG solutions was studied during both heating (5-85 °C) and cooling (85-5 °C) processes. The complex viscosity of AHSG was greater compared to the apparent viscosity, indicating the disruption of AHSG network structure under continuous shear rates and deviation from the Cox-Merz rule. During the initial heating, the storage modulus showed a decreasing trend and, with a further increase in temperature, the magnitude of storage modulus increased. The influence of temperature on the storage modulus was considerable when a higher heating rate was applied. AHSG can be applied as a thickening and stabilizing agents in food products that require good stability against temperature. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

In vitro properties of concentrated canine platelets stored in two additive solutions: a comparative study.

PubMed

Hlavac, N; Lasta, C S; Dalmolin, M L; Lacerda, L A; de Korte, D; Marcondes, N A; Terra, S R; Fernandes, F B; González, F H D

2017-11-15

Platelet transfusion therapy poses many challenges in veterinary clinical practice. Lack of readily available blood donors, short shelf-life, and inability to administer a sufficient number of platelets to meet a dog's transfusion need are the major difficulties encountered. Platelet additive solutions are already in use at American and European human blood banks, showing to be a realistic alternative. This study compares the in vitro platelet function in plasma, Composol, or SSP+ during storage for 13 days. Platelet rich plasma-platelet concentrate with 35% plasma and 65% platelet additive solutions (Composol or SSP+) and a control group (100% plasma) were prepared. Swirling, platelet count, blood gases, metabolic variables, platelet activation markers, and apoptosis markers were analyzed on days 1, 5, 9 and 13. Swirling was well preserved and pH was acceptable (> 6.2) during storage for all platelet additive solutions units until day 9. SSP + units showed more stable pH and metabolic variables until day 13. Platelets in plasma showed higher glucose consumption than in Composol or in SSP+. The platelet additive solutions units showed better platelet metabolism maintenance, reduced glucose consumption and lactate production. The apoptotic markers were still low for 9 days in platelet concentrates with platelet additive solutions, suggesting the possibility to extend the shelf life with the use of SSP+ or Composol. Our findings suggest that the uses of Composol and SSP+ in canine platelet concentrates are potential alternatives in veterinary blood banks.

Interaction between xanthan gum and cationic cellulose JR400 in aqueous solution.

PubMed

Li, Haiping; Hou, Wanguo; Li, Xiuzhi

2012-06-05

The electrostatic and hydrogen bonding interactions between xanthan gum (XG) and semisynthetic cationic cellulose (JR400) in aqueous solution are investigated via stability map, FT-IR spectra, thermogravimetric analysis, potentiometric measurement and rheological method. The stability map shows three regions, a stable region with XG as the major component, a flocculated region and another stable region with JR400 as the major component. The stability of mixing system depends on both the concentration fraction of JR400 (fJR) and the overlapping concentrations of these two polymers. In the region near the stoichiometric fJR, the mixture shows stoichiometric flocculation, which is independent of the total polymer concentration. However, in the regions away from the stoichiometric fJR, the mixtures are stable when the concentration of major polymer component is higher than its overlapping concentration. In stable regions, the electrostatic and hydrogen bonding interactions can enhance the viscosity of mixing system at appropriate fJR values. Copyright © 2012 Elsevier Ltd. All rights reserved.

Application of solution-processed V2O5 in inverted polymer solar cells based on fluorine-doped tin oxide substrate.

PubMed

Wu, Jian; Zhang, Yupeng; He, Yeyuan; Liu, Chunyu; Guolt, Wenbin; Ruan, Shengping

2014-06-01

We used a hydrothermal method to synthesis the solution-processed V2O5 as anode buffer layer, which applied on inverted polymer solar cells based on FTO substrate. The structure of the device is glass/FTO/TiO2/P3HT:PCBM/V2O5/Ag. We discussed the dependence of device performance on the concentrations of V2O5 solution. It is found that when the concentration of V2O5 is 300 microg/ml, the power conversion efficiency (PCE of 2.38%) is the highest, which is much higher than that of the device without anode buffer layer (PCE of only 0.87%). Moreover, it can significantly reduce the energy consumption and make it more cost-effective.

Relationships among foliar chemistry, foliar polyamines, and soil chemistry in red spruce trees growing across the northeastern United States

USGS Publications Warehouse

Minocha, R.; Shortle, W.C.; Lawrence, G.B.; David, M.B.; Minocha, S.C.

1997-01-01

Forest trees are constantly exposed to various types of natural and anthropogenic stressors. A major long-term goal of our research is to develop a set of early physiological and biochemical markers of stress in trees before the appearance of visual symptoms. Six red spruce (Picea rubens Sarg.) stands from the northeastern United States were selected for collection of soil and foliage samples. All of the chosen sites had soil solution pH values below 4.0 in the Oa horizon but varied in their geochemistry. Some of these sites were apparently under some form of environmental stress as indicated by a large number of dead and dying red spruce trees. Samples of soil and needles (from apparently healthy red spruce trees) were collected from these sites four times during a two-year period. The needles were analyzed for perchloric acid-soluble polyamines and exchangeable inorganic ions. Soil and soil solution samples from the Oa and B horizons were analyzed for their exchange chemistry. The data showed a strong positive correlation between Ca and Mg concentrations in the needles and in the Oa horizon of the soil. However, needles from trees growing on relatively Ca-rich soils with a low exchangeable Al concentration and a low Al:Ca soil solution ratio had significantly lower concentrations of putrescine and spermidine than those growing on Ca-poor soils with a high exchangeable Al concentration and a high Al:Ca soil solution in the Oa horizon. The magnitude of this change was several fold higher for putrescine concentrations than for spermidine concentrations. Neither putrescine nor spermidine were correlated with soil solution Ca, Mg, and Al concentrations in the B horizon. The putrescine concentrations of the needles always correlated significantly with exchangeable Al (r2=0.73, p???0.05) and still solution Al:Ca ratios (r2=0.91, p???0.01) of the Oa horizon. This suggests that in conjunction with soil chemistry, putrescine and/or spermidine may be used as a potential early indicator of Al stress before the appearance of visual symptoms in red spruce trees.

Seawater-driven forward osmosis for enriching nitrogen and phosphorous in treated municipal wastewater: effect of membrane properties and feed solution chemistry.

PubMed

Xue, Wenchao; Tobino, Tomohiro; Nakajima, Fumiyuki; Yamamoto, Kazuo

2015-02-01

Seawater-driven forward osmosis (FO) is considered to be a novel strategy to concentrate nutrients in treated municipal wastewater for further recovery as well as simultaneous discharge of highly purified wastewater into the sea with low cost. As a preliminary test, the performance of FO membranes in concentrating nutrients was investigated by both batch experiments and model simulation approaches. With synthetic seawater as the draw solution, the dissolved organic carbon, phosphate, and ammonia in the effluent from a membrane bioreactor (MBR) treating municipal wastewater were 2.3-fold, 2.3-fold, and 2.1-fold, respectively, concentrated by the FO process with approximately 57% of water reduction. Most of the dissolved components, including trace metals in the MBR effluent, were highly retained (>80%) in the feed side, indicating high water quality of permeate to be discharged. The effect of membrane properties on the nutrient enrichment performance was investigated by comparing three types of FO membranes. Interestingly, a polyamide membrane possessing a high negative charge demonstrated a poor capability of retaining ammonia, which was hypothesized because of an ion exchange-like mechanism across the membrane prompted by the high ionic concentration of the draw solution. A feed solution pH of 7 was demonstrated to be an optimum condition for improving the overall retention of nutrients, especially for ammonia because of the pH-dependent speciation of ammonia/ammonium forms. The modeling results showed that higher than 10-fold concentrations of ammonia and phosphate are achievable by seawater-driven FO with a draw solution to feed solution volume ratio of 2:1. The enriched municipal wastewater contains nitrogen and phosphorous concentrations comparable with typical animal wastewater and anaerobic digestion effluent, which are used for direct nutrient recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

Corrosion property of 9Cr-ODS steel in nitric acid solution for spent nuclear fuel reprocessing

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

Takeuchi, M.; Koizumi, T.; Inoue, M.

2013-07-01

Corrosion tests of oxide dispersion strengthened with 9% Cr (9Cr-ODS) steel, which is one of the desirable materials for cladding tube of sodium-cooled fast reactors, in pure nitric acid solution, spent FBR fuel solution, and its simulated solution were performed to understand the corrosion behavior in a spent nuclear fuel reprocessing. In this study, the 9Cr-ODS steel with lower effective chromium content was evaluated to understand the corrosion behavior conservatively. As results, the tube-type specimens of the 9Cr-ODS steels suffered severe weight loss owing to active dissolution at the beginning of the immersion test in pure nitric acid solution inmore » the range from 1 to 3.5 M. In contrast, the weight loss was decreased and they showed a stable corrosion in the higher nitric acid concentration, the dissolved FBR fuel solution, and its simulated solution by passivation. The corrosion rates of the 9Cr-ODS steel in the dissolved FBR fuel solution and its simulated solution were 1-2 mm/y and showed good agreement with each other. The passivation was caused by the shift of corrosion potential to noble side owing to increase in nitric acid concentration or oxidative ions in the dissolved FBR fuel solution and the simulated spent fuel solution. (authors)« less

Bioavailable concentrations of germanium and rare earth elements in soil as affected by low molecular weight organic acids and root exudates

NASA Astrophysics Data System (ADS)

Wiche, Oliver; Székely, Balázs; Kummer, Nicolai-Alexeji; Heinemann, Ute; Tesch, Silke; Heilmeier, Hermann

2014-05-01

Availability of elements in soil to plant is generally dependent on the solubility and mobility of elements in soil solution which is controlled by soil, elemental properties and plant-soil interactions. Low molecular organic acids or other root exudates may increase mobility and availability of certain elements for plants as an effect of lowering pH in the rhizosphere and complexation. However, these processes take place in a larger volume in soil, therefore to understand their nature, it is also important to know in which layers of the soil what factors modify these processes. In this work the influence of citric acid and root exudates of white lupin (Lupinus albus L.) on bioavailable concentrations of germanium, lanthan, neodymium, gadolinium and erbium in soil solution and uptake in root and shoot of rape (Brassica napus L.), comfrey (Symphytum officinale L.), common millet (Panicum milliaceum L.) and oat (Avena sativa L.) was investigated. Two different pot experiments were conducted: (1) the mentioned plant species were treated with nutrient solutions containing various amount of citric acid; (2) white lupin was cultivated in mixed culture (0 % lupin, 33 % lupin) with oat (Avena sativa L.) and soil solution was obtained by plastic suction cups placed at various depths. As a result, addition of citric acid significantly increased germanium concentrations in plant tissue of comfrey and rape and increased translocation of germanium, lanthan, neodymium, gadolinium and erbium from root to shoot. The cultivation of white lupin in mixed culture with oat led to significantly higher concentrations of germanium and increasing concentrations of lanthan, neodymium, gadolinium and erbium in soil solution and aboveground plant tissue. In these pots concentrations of citric acid in soil solution were significantly higher than in the control. The results show, that low molecular organic acids exuded by plant roots are of great importance for the mobilization of germanium, lanthan, neodymium, gadolinium and erbium in the rhizosphere and therefore the enhancement of bioavailability of the mentioned elements to plants. Based on the suction cup experiment we conclude that in vertical soil profile the bioavailable germanium is heavily affected by the activity of exudates, as the complexation processes of germanium take place at the root zone and below affected by the interplay of the infiltration of citric acid solutions and the actually produced exudates. These studies have been carried out in the framework of the PhytoGerm project, financed by the Federal Ministry of Education and Research, Germany. BS contributed as an Alexander von Humboldt Research Fellow. The authors are grateful to students and laboratory assistants contributing in the field work and sample preparation.

Neutralization of Plutonium and Enriched Uranium Solutions Containing Gadolinium as a Neutron Poison

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

BRONIKOWSKI, MG.

2004-04-01

Materials currently being dissolved in the HB-Line Facility will result in an accumulated solution containing an estimated uranium:plutonium (U:Pu) ratio of 4.3:1 and an 235U enrichment estimated at 30 per cent The U:Pu ratio and the enrichment are outside the evaluated concentration range for disposition to high level waste (HLW) using gadolinium (Gd) as a neutron poison. To confirm that the solution generated during the current HB-Line dissolving campaign can be poisoned with Gd, neutralized and discarded to the Savannah River Site (SRS) high level waste (HLW) system without undue nuclear safety concerns the caustic precipitation of surrogate solutions wasmore » examined. Experiments were performed with a U/Pu/Gd solution representative of the HB-Line estimated concentration ratio and also a U/Gd solution. Depleted U was used in the experiments as the enrichment of the U will not affect the chemical behavior during neutralization, but will affect the amount of Gd added to the solution. Settling behavior of the neutralized solutions was found to be comparable to previous studies. The neutralized solutions mixed easily and had expected densities of typical neutralized waste. The neutralized solids were found to be homogeneous and less than 20 microns in size. Partially neutralized solids were more amorphous than the fully neutralized solids. Based on the results of these experiments, Gd was found to be a viable poison for neutralizing a U/Pu/Gd solution with a U:Pu mass ratio of 4.3:1 thus extending the U:Pu mass ratio from the previously investigated 0-3:1 to 4.3:1. However, further work is needed to allow higher U concentrations or U:Pu ratios greater than investigated in this work.« less

Direct microscopic observation of forward osmosis membrane fouling.

PubMed

Wang, Yining; Wicaksana, Filicia; Tang, Chuyang Y; Fane, Anthony G

2010-09-15

This study describes the application of a noninvasive direct microscopic observation method for characterizing fouling of a forward osmosis (FO) membrane. The effect of the draw solution concentration, membrane orientation, and feed spacer on FO fouling was systematically investigated in a cross-flow setup using latex particles as model foulant in the feedwater. Higher draw solution (DS) concentrations (and thus increased flux levels) resulted in dramatic increase in the surface coverage by latex particles, suggesting that the critical flux concept might be applicable even for the osmotically driven FO process. Under identical draw solution concentrations, the active-layer-facing-the-feed-solution orientation (AL-FS) experienced significantly less fouling compared to the alternative orientation. This may be explained by the lower water flux in AL-FS, which is consistent with the critical flux concept. The use of a feed spacer not only dramatically enhanced the initial flux of the FO membrane, but also significantly improved the flux stability during FO fouling. Despite such beneficial effects of using the feed spacer, a significant amount of particle accumulation was found near the spacer filament, suggesting further opportunities for improved spacer design. To the best of the authors' knowledge, this is the first direct microscopic observation study on FO fouling.

Indirect Competitive Enzyme-Linked Immunosorbent Assay (ELISA).

PubMed

Kohl, Thomas O; Ascoli, Carl A

2017-07-05

The indirect competitive ELISA (indirect cELISA) pits plate-immobilized antigen against antigens in solution for binding to antigen-specific antibody. The antigens in solution are in the test sample and are first incubated with antigen-specific antibody. These antibody-antigen complexes are then added to microtiter plates whose wells have been coated with purified antigen. The wells are washed to remove unbound antigen-antibody complexes and free antigen. A reporter-labeled secondary antibody is then added followed by the addition of substrate. Substrate hydrolysis yields a signal that is inversely proportional to antigen concentration within the sample. This is because when antigen concentration is high in the test sample, most of the antibody is bound before adding the solution to the plate. Most of the antibody remains in solution (as complexes) and is thus washed away before the addition of the reporter-labeled secondary antibody and substrate. Thus, the higher the antigen concentration in the test sample, the weaker the resultant signal in the detection step. The indirect cELISA is often used for competitive detection and quantification of antibodies against viral diseases in biological samples. © 2017 Cold Spring Harbor Laboratory Press.

Improved ferroelectric and pyroelectric parameters in iminodiacetic acid doped TGS crystal

NASA Astrophysics Data System (ADS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2010-01-01

Single crystals of Iminodiacetic acid (HN(CH 2COOH) 2) doped Triglycine sulphate (IDATGS) has been grown from aqueous solution at constant temperature by slow evaporation technique. The concentration of the dopant in the TGS solution was 2 mol%. The X-ray diffraction analysis indicates that there is significant change in the lattice parameters compared to pure TGS crystal. The IDATGS crystal has larger transition temperature and observed higher and uniform figure of merit over most part of the ferroelectric phase. These crystals also exhibit higher internal bias field and micro-hardness number compared to pure TGS. Therefore IDATGS may be a potential material for IR detectors.

Demetallization of Enterococcus faecalis biofilm: a preliminary study

PubMed Central

ESTRELA, Carlos; COSTA E SILVA, Rodrigo; URBAN, Roberta Cerasi; GONÇALVES, Pablo José; SILVA, Júlio A.; ESTRELA, Cyntia R.A.; PECORA, Jesus Djalma; PETERS, Ove A.

2018-01-01

Abstract Objectives To determine the concentration of calcium, iron, manganese and zinc ions after the application of chelator to Enterococcus faecalis biofilms. Material and Methods Fifty bovine maxillary central incisors were prepared and inoculated with E. faecalis for 60 days. The following were used as irrigation solutions: 17% EDTA (pH 3, 7 and 10), 2.5% sodium hypochlorite (NaOCl) combined with 17% EDTA (pH 3, 7 and 10), distilled water (pH 3, 7 and 10), and 2.5% NaOCl. Each solution was kept in the root canal for five minutes. Fifteen uncontaminated root canals were irrigated with 17% EDTA (pH 3, 7 and 10). Six teeth were used as bacterial control. The number of calcium, iron, manganese and zinc ions was determined using flame atomic absorption spectrometry. Mean ± standard deviation (SD) values were used for descriptive statistics. Results Calcium chelation using 17% EDTA at pH 7 was higher than at pH 3 and 10, regardless of whether bacterial biofilm was present. The highest concentration of iron occurred at pH 3 in the presence of bacterial biofilm. The highest concentration of manganese found was 2.5% NaOCl and 17% EDTA at pH 7 in the presence of bacterial biofilm. Zinc levels were not detectable. Conclusions The pH of chelating agents affected the removal of calcium, iron, and manganese ions. The concentration of iron ions in root canals with bacterial biofilm was higher after the use of 17% EDTA at pH 3 than after the use of the other solutions at all pH levels. PMID:29451651

Effects of sodium in hydration solution on plasma methotrexate concentrations following high-dose methotrexate in children with acute lymphoblastic leukemia.

PubMed

Kinoshita, Akitoshi; Kurosawa, Yoshihiro; Kondoh, Kensuke; Suzuki, Toshio; Manabe, Atsushi; Inukai, Takeshi; Sugita, Kanji; Nakazawa, Shinpei

2003-03-01

To test whether a higher sodium dose in the hydration solution may facilitate faster methotrexate (MTX) elimination as compared with a lower sodium dose following high-dose MTX (HDMTX) treatment. Intravenous solutions with alternate doses of sodium (regimen A 70 mEq/l, regimen B 100 mEq/l) were given to 30 children with acute lymphoblastic leukemia in two courses of HDMTX in a randomized crossover fashion. The plasma MTX concentrations every 24 h from the beginning of MTX administration and the adverse events associated with HDMTX were compared between the two hydration regimens. The plasma MTX concentrations were similar in the two hydration regimens at 24 h (A 50.9+/-7.4 vs B 40.9+/-5.4 microM, means+/- SE, P=0.17), but was significantly lower in regimen B at 48 and 72 h (A 0.65+/-0.17 vs B 0.27+/-0.03 microM, P=0.04; and A 0.14+/-0.03 vs B 0.05+/-0.01 microM, P=0.003). The time during which MTX plasma concentrations exceeded 0.1 microM was significantly longer in regimen A than in regimen B (A 3.83+/-0.18 vs B 3.13+/-0.06 days, P=0.001). The incidences of adverse events were similar between the two regimens ( P=0.78), and severe adverse events were not seen in either regimen. Hydration with a higher sodium dose facilitated faster MTX elimination following HDMTX. Sodium may have a beneficial effect on MTX-induced nephrotoxicity.

Water activities of NaClO4, Ca(ClO4)2, and Mg(ClO4)2 brines from experimental heat capacities: Water activity >0.6 below 200 K

NASA Astrophysics Data System (ADS)

Toner, J. D.; Catling, D. C.

2016-05-01

Perchlorate salts found on Mars are extremely hygroscopic and form low eutectic temperature aqueous solutions, which could allow liquid water to exist on Mars despite cold and dry conditions. The formation, dynamics, and potential habitability of perchlorate salt solutions can be broadly understood in terms of water activity. Water activity controls condensation and evaporation of water vapor in brines, deliquescence and efflorescence of crystalline salts, and ice formation during freezing. Furthermore, water activity is a basic parameter defining the habitability of aqueous solutions. Despite the importance of water activity, its value in perchlorate solutions has only been measured at 298.15 K and at the freezing point of water. To address this lack of data, we have determined water activities in NaClO4, Ca(ClO4)2, and Mg(ClO4)2 solutions using experimental heat capacities measured by Differential Scanning Calorimetry. Our results include concentrations up to near-saturation and temperatures ranging from 298.15 to 178 K. We find that water activities in NaClO4 solutions increase with decreasing temperature, by as much as 0.25 aw from 298.15 to 178 K. Consequently, aw reaches ∼0.6-0.7 even for concentrations up to 15 molal NaClO4 below 200 K. In contrast, water activities in Ca(ClO4)2 and Mg(ClO4)2 solutions generally decrease with decreasing temperature. The temperature dependence of water activity indicates that low-temperature NaClO4 solutions will evaporate and deliquesce at higher relative humidity, crystallize ice at higher temperature, and potentially be more habitable for life (at least in terms of water activity) compared to solutions at 298.15 K. The opposite effects occur in Ca(ClO4)2 and Mg(ClO4)2 solutions.

Association between mortality and replacement solution bicarbonate concentration in continuous renal replacement therapy: A propensity-matched cohort study

PubMed Central

Thongprayoon, Charat; Cheungpasitporn, Wisit; Iacovella, Gina M.; Akhoundi, Abbasali; Albright, Robert C.

2017-01-01

Background Given the known deleterious effects seen with bicarbonate supplementation for acidemia, we hypothesized that utilizing high bicarbonate concentration replacement solution in continuous venovenous hemofiltration (CVVH) would be independently associated with higher mortality. Methods In a propensity score-matched historical cohort study conducted at a single tertiary care center from December 9, 2006, through December 31, 2009, a total of 287consecutive adult critically ill patients with Stage III acute kidney injury (AKI) requiring CVVH were enrolled. We excluded patients on maintenance dialysis, those who received other modalities of continuous renal replacement therapies, and patients that received a mixed of 22 and 32 mEq/L bicarbonate solution pre- and post-filter. The primary outcome was in-hospital and 90-day mortality rates. Results Among enrollees, 68 were used 32 mEq/L bicarbonate solution, and 219 received 22mEq/L bicarbonate solution for CVVH. Patients on 32 mEq/L bicarbonate solution were more often non-surgical, had lower pH and bicarbonate level but had higher blood potassium and phosphorus levels in comparison with those on 22 mEq/L bicarbonate solution. After adjustment for the baseline characteristics, the use of 32 bicarbonate solution was significantly associated with increased in-hospital (HR = 1.94; 95% CI 1.02–3.79) and 90-day mortality (HR = 1.50; 95% CI 1.03–2.14). There was a significant increase in the hospital (p = .03) and 90-day (p = .04) mortality between the 22 vs. 32 mEq/L bicarbonate solution groups following propensity matching. Conclusion Our data showed there is a strong association between using high bicarbonate solution and mortality independent of severity of illness and comorbid conditions. These findings need to be evaluated further in prospective studies. PMID:28957333

Supercharging Protein Complexes from Aqueous Solution Disrupts their Native Conformations

NASA Astrophysics Data System (ADS)

Sterling, Harry J.; Kintzer, Alexander F.; Feld, Geoffrey K.; Cassou, Catherine A.; Krantz, Bryan A.; Williams, Evan R.

2012-02-01

The effects of aqueous solution supercharging on the solution- and gas-phase structures of two protein complexes were investigated using traveling-wave ion mobility-mass spectrometry (TWIMS-MS). Low initial concentrations of m-nitrobenzyl alcohol ( m-NBA) in the electrospray ionization (ESI) solution can effectively increase the charge of concanavalin A dimers and tetramers, but at higher m-NBA concentrations, the increases in charge are accompanied by solution-phase dissociation of the dimers and up to a ~22% increase in the collision cross section (CCS) of the tetramers. With just 0.8% m-NBA added to the ESI solution of a ~630 kDa anthrax toxin octamer complex, the average charge is increased by only ~4% compared with the "native" complex, but it is sufficiently destabilized so that extensive gas-phase fragmentation occurs in the relatively high pressure regions of the TWIMS device. Anthrax toxin complexes exist in either a prechannel or a transmembrane channel state. With m-NBA, the prechannel state of the complex has the same CCS/charge ratio in the gas phase as the transmembrane channel state of the same complex formed without m-NBA, yet undergoes extensive dissociation, indicating that destabilization from supercharging occurs in the ESI droplet prior to ion formation and is not a result of Coulombic destabilization in the gas phase as a result of higher charging. These results demonstrate that the supercharging of large protein complexes is the result of conformational changes induced by the reagents in the ESI droplets, where enrichment of the supercharging reagent during droplet evaporation occurs.

Uranium chemistry in stack solutions and leachates of phosphogypsum disposed at a coastal area in Cyprus.

PubMed

Lysandrou, M; Pashalidis, I

2008-02-01

The effect of the matrix composition (main constituents) on the concentration and chemical behavior of uranium in phosphogypsum stack solutions and leachates has been investigated. Solid and aqueous samples were taken from three different sub-areas of a phosphogypsum stack at a coastal area in Vasilikos (Cyprus). The sub-areas are characterized whether by their acidity (e.g. "aged" and "non-aged" phosphogypsum) or by their salt content, originating from pulping water during wet stacking or (after deposition) from the adjacent sea. Measurements in stack solutions and leachates showed that phosphogypsum characteristics affect both, the concentration and the chemical behavior of uranium in solution. Uranium concentration in solutions of increased salinity is up to three orders of magnitude higher than in solutions of low salinity and this is attributed to the effect of ionic strength on the solubility of phosphogypsum. Modelling showed that uranium in stack solutions is predominantly present in the form of uranium(VI) phosphate complexes (e.g. UO(2)(H(2)PO(4))(2), UO(2)HPO(4)), whereas in leachates uranium(VI) fluoro complexes (e.g. UO(2)F(2), UO(2)F(3)(-)) are predominant in solution. The latter indicates that elution of uranium from phosphogypsum takes places most probably in the form of fluoro complexes. Both, effective elution by saline water and direct migration of uranium to the sea, where it forms very stable uranium(VI) carbonato complexes, indicate that the adjacent sea will be the final receptor of uranium released from Vasilikos phosphogypsum.

Dibutyl Phosphoric Acid Solubility in High-Acid, Uranium-Bearing Solutions at SRS

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

Pierce, R.A.

1998-10-02

The Savannah River Site has enriched uranium (EU) solution which has been stored for almost 10 years since being purified in the second uranium cycle of the H area solvent extraction process. The concentrations in solution are approximately 6 g/L U and about 0.1 M nitric acid. Residual tributylphosphate in the solutions has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 50 mg/L. Uranium is known to form compounds with the dibutylphosphate ion (DBP) which have limited solubility. The potential to form uranium-DBP solids raises a nuclear criticality safety issue. Prior SRTC tests (WSRC-TR-98-00188) showed that U-DBPmore » solids precipitate at concentrations potentially attainable during the storage of enriched uranium solutions. Furthermore, evaporation of the existing EUS solution without additional acidification could result in the precipitation of U-DBP solids if the DBP concentration in the resulting solution exceeds 110 mg/L at ambient temperature. The same potential exists for evaporation of unwashed 1CU solutions. As a follow-up to the earlier studies, SRTC studied the solubility limits for solutions containing acid concentrations above 0.5M HNO3. The data obtained in these tests reveals a shift to higher levels of DBP solubility above 0.5M HNO3 for both 6 g/L and 12 g/L uranium solutions. Analysis of U-DBP solids from the tests identified a mixture of different molecular structures for the solids created. The analysis distinguished UO2(DBP)2 as the dominant compound present at low acid concentrations. As the acid concentration increases, the crystalline UO2(DBP)2 shows molecular substitutions and an increase in amorphous content. Further analysis by methods not available at SRS will be needed to better identify the specific compounds present. This data indicates that acidification prior to evaporation can be used to increase the margin of safety for the storage of the EUS solutions. Subsequent experimentation evaluated options for absorbing HDBP from solution using either activated carbon or anion exchange resin. The activated carbon outperformed the anion exchange resin. Activated carbon absorbs DBP rapidly and has demonstrated the capability of absorbing 15 mg of DBP per gram of activated carbon. Analytical results also show that activated carbon absorbs uranium up to 17 mg per gram of carbon. It is speculated that the uranium absorbed is part of a soluble U-DBP complex that has been absorbed. Additional testing must still be performed to 1) establish absorption limits for uranium for anion exchange resin, 2) evaluate desorption characteristics of uranium and DBP, and 3) study the possibility of re-using the absorbent.« less

Soil solution Zn and pH dynamics in non-rhizosphere soil and in the rhizosphere of Thlaspi caerulescens grown in a Zn/Cd-contaminated soil.

PubMed

Luo, Y M; Christie, P; Baker, A J

2000-07-01

Temporal changes in soil solution properties and metal speciation were studied in non-rhizosphere soil and in the rhizosphere of the hyperaccumulator Thlaspi caerulescens J. & C. Presl (population from Prayon, Belgium) grown in a Zn- and Cd-contaminated soil. This paper focuses on soil solution Zn and pH dynamics during phytoextraction. The concentration of Zn in both non-rhizosphere and rhizosphere soil solutions decreased from 23 mg/l at the beginning to 2 mg/l at the end of the experiment (84 days after transplanting of seedlings), mainly due to chemical sorption. There was no significant difference in overall Zn concentration between the planted and the unplanted soil solutions (P > 0.05). Soil solution pH decreased initially and then increased slightly in both planted and unplanted soil zones. From 60 to 84 days after transplanting, the pH of the rhizosphere soil solution was higher than that of non-rhizosphere soil solution (P<0.05). Zn uptake by the hyperaccumulator plants was 8.8 mg per pot (each containing 1 kg oven-dry soil) on average. The data indicate that the potential of T. caerulescens to remove Zn from contaminated soil may not be related to acidification of the rhizosphere.

Fractionation of aquatic natural organic matter upon sorption to goethite and kaolinite

USGS Publications Warehouse

Meier, M.; Namjesnik-Dejanovic, K.; Maurice, P.A.; Chin, Y.-P.; Aiken, G.R.

1999-01-01

Natural organic matter (NOM) consists of a complex mixture of organic molecules; previous studies have suggested that preferential sorption of higher molecular weight, more hydrophobic, and more aromatic components may lead to fractionation of the NOM pool upon passage through porous media. Our work expands upon previous studies by quantifying the change in solution-phase weight average molecular weight (M(w)) upon sorption of bulk (rather than isolated) surface water NOM from the Suwannee River (SR) and the Great Dismal Swamp (GDS) to goethite and kaolinite at different sorption densities and at pH 4, 22??C. High pressure size exclusion chromatography (HPSEC) was used to quantify changes in M(w) upon sorption, and molar absorptivities at ?? = 280 nm were used to approximate changes in solution NOM aromaticity. Two SR water samples were used, with M(w) = 2320 and 2200 Da; a single GDS sample was used, with M(w) = 1890 Da. The SR NOM was slightly more hydrophobic and aromatic. These differences were reflected in greater sorption of SR NOM than GDS NOM. Both surface water NOMs showed a much greater affinity for goethite than for kaolinite. HPSEC analysis of the NOM remaining in solution after 24 h reaction time with geothite revealed that the largest changes in solution phase M(w)s (decreases by 900-1700 Da) occurred at relatively low equilibrium sorbate concentrations (approximately 5-20 mg C 1-1); the decrease in solution M(w) suggested that reactive surface sites were occupied disproportionately by large and intermediate size NOM moieties. At higher equilibrium NOM concentrations (>20 mg C 1-1), as percent adsorption decreased, M(w) in solution was similar to original samples. A smaller decrease in solution NOM M(w) (300-500 Da at 10-20 mg C 1-1 ~ 100 Da at > 20 mg) also occurred upon sorption to kaolinite. Overall, our results showed that factors (as related to NOM composition, clay mineral surface properties, and position along the sorption isotherm) which promote a higher percent sorption lead to the most pronounced decreases in solution M(w).

Anionic surfactant enhanced phosphate desorption from Mg/Al-layered double hydroxides by micelle formation.

PubMed

Shimamura, Akihiro; Jones, Mark I; Metson, James B

2013-12-01

Desorption of interlayer hydrogen phosphate (HPO4) from hydrogen phosphate intercalated Mg/Al-layered double hydroxide (LDH-HPO4) by anion exchange with surfactant anions has been investigated under controlled conditions. Three types of surfactant, Dodecylbenzenesulphonate (DBS), Dodecylsulphate (DS) and 1-Octanesulphonate (OS), anions were used for intercalation experiments over a range of concentrations, and for all solutions, it was shown that the desorption of hydrogen phosphate is enhanced at concentrations close to the critical micelle concentration (CMC). Intercalation of the surfactant anions into LDH-HPO4 was confirmed by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning electron microscopy (SEM). More than 90% removal of the hydrogen phosphate was achieved at CMC. Repeat adsorption tests to investigate recyclability showed that desorption with 0.005 M DBS improved subsequent phosphate re-adsorption, allowing around 90% of the original adsorption over three cycles. This is much higher than when desorption was conducted using either Na2CO3 or NaCl-NaOH solutions, even at much higher concentrations. This study suggests potential economic and environmental advantages in using these surfactants in improving the cycling performance of LDH materials as absorbents for clean-up of water systems. Copyright © 2013 Elsevier Inc. All rights reserved.

Effect of saline waste solution infiltration rates on uranium retention and spatial distribution in Hanford sediments.

PubMed

Wan, Jiamin; Tokunaga, Tetsu K; Kim, Yongman; Wang, Zheming; Lanzirotti, Antonio; Saiz, Eduardo; Serne, R Jeffrey

2008-03-15

The accidental overfilling of waste liquid from tank BX-102 at the Hanford Site in 1951 put about 10 t of U(VI) into the vadose zone. In order to understand the dominant geochemical reactions and transport processes that occurred during the initial infiltration and to help understand current spatial distribution, we simulated the waste liquid spilling event in laboratory sediment columns using synthesized metal waste solution. We found that, as the plume propagated through sediments, pH decreased greatly (as much as 4 units) at the moving plume front. Infiltration flow rates strongly affect U behavior. Slower flow rates resulted in higher sediment-associated U concentrations, and higher flow rates (> or =5 cm/day) permitted practically unretarded U transport. Therefore, given the very high Ksat of most of Hanford formation, the low permeability zones within the sediment could have been most important in retaining high concentrations of U during initial release into the vadose zone. Massive amount of colloids, including U-colloids, formed at the plume fronts. Total U concentrations (aqueous and colloid) within plume fronts exceeded the source concentration by up to 5-fold. Uranium colloid formation and accumulation at the neutralized plume front could be one mechanism responsible for highly heterogeneous U distribution observed in the contaminated Hanford vadose zone.

Electrochemical probing of high-level radioactive waste tanks containing washed sludge and precipitates

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

Bickford, D.F.; Congdon, J.W.; Oblath, S.B.

1986-12-01

At the US Department of Energy's Savannah River Plant, corrosion of carbon steel storage tanks containing alkaline, high-level radioactive waste is controlled by specification of limits on waste composition and temperature. Processes for the preparation of waste for final disposal will result in waste with low corrosion inhibitor concentrations and, in some cases, high aromatic organic concentrations, neither of which are characteristic of previous operations. Laboratory tests, conducted to determine minimum corrosion inhibitor levels indicated pitting of carbon steel near the waterline for proposed storage conditions. In situ electrochemical measurements of full-scale radioactive process demonstrations have been conducted to assessmore » the validity of laboratory tests. Probes included pH, Eh (potential relative to a standard hydrogen electrode), tank potential, and alloy coupons. In situ results are compared to those of the laboratory tests, with particular regard given to simulated solution composition. Transition metal hydroxide sludge contains strong passivating species for carbon steel. Washed precipitate contains organic species that lower solution pH and tend to reduce passivating films, requiring higher inhibitor concentrations than the 0.01 molar nitrite required for reactor fuel reprocessing wastes. Periodic agitation, to keep the organic phase suspended, or cathodic protection are possible alternatives to higher nitrite inhibitor concentrations.« less

Monohydrocalcite: a promising remediation material for hazardous anions

PubMed Central

Fukushi, Keisuke; Munemoto, Takashi; Sakai, Minoru; Yagi, Shintaro

2011-01-01

The formation conditions, solubility and stability of monohydrocalcite (MHC, CaCO3·H2O), as well as sorption behaviors of toxic anions on MHC, are reviewed to evaluate MHC as a remediation material for hazardous oxyanions. MHC is a rare mineral in geological settings that occurs in recent sediments in saline lakes. Water temperature does not seem to be an important factor for MHC formation. The pH of lake water is usually higher than 8 and the Mg/Ca ratio exceeds 4. MHC synthesis experiments as a function of time indicate that MHC is formed from amorphous calcium carbonate and transforms to calcite and/or aragonite. Most studies show that MHC forms from solutions containing Mg, which inhibits the formation of stable calcium carbonates. The solubility of MHC is higher than those of calcite, aragonite and vaterite, but lower than those of ikaite and amorphous calcium carbonate at ambient temperature. The solubility of MHC decreases with temperature. MHC is unstable and readily transforms to calcite or aragonite. The transformation consists of the dissolution of MHC and the subsequent formation of stable phases from the solution. The rate-limiting steps of the transformation of MHC are the nucleation and growth of stable crystalline phases. Natural occurrences indicate that certain additives, particularly PO4 and Mg, stabilize MHC. Laboratory studies confirm that a small amount of PO4 in solution (>30 μM) can significantly inhibit the transformation of MHC. MHC has a higher sorption capacity for PO4 than calcite and aragonite. The modes of PO4 uptake are adsorption on the MHC surface at moderate phosphate concentrations and precipitation of secondary calcium phosphate minerals at higher concentrations. Arsenate is most likely removed from the solution during the transformation of MHC. The proposed sorption mechanism of arsenate is coprecipitation during crystallization of aragonite. The arsenic sorption capacity by MHC is significantly higher than simple adsorption on calcite. PMID:27877452

Monohydrocalcite: a promising remediation material for hazardous anions.

PubMed

Fukushi, Keisuke; Munemoto, Takashi; Sakai, Minoru; Yagi, Shintaro

2011-12-01

The formation conditions, solubility and stability of monohydrocalcite (MHC, CaCO 3 ·H 2 O), as well as sorption behaviors of toxic anions on MHC, are reviewed to evaluate MHC as a remediation material for hazardous oxyanions. MHC is a rare mineral in geological settings that occurs in recent sediments in saline lakes. Water temperature does not seem to be an important factor for MHC formation. The pH of lake water is usually higher than 8 and the Mg/Ca ratio exceeds 4. MHC synthesis experiments as a function of time indicate that MHC is formed from amorphous calcium carbonate and transforms to calcite and/or aragonite. Most studies show that MHC forms from solutions containing Mg, which inhibits the formation of stable calcium carbonates. The solubility of MHC is higher than those of calcite, aragonite and vaterite, but lower than those of ikaite and amorphous calcium carbonate at ambient temperature. The solubility of MHC decreases with temperature. MHC is unstable and readily transforms to calcite or aragonite. The transformation consists of the dissolution of MHC and the subsequent formation of stable phases from the solution. The rate-limiting steps of the transformation of MHC are the nucleation and growth of stable crystalline phases. Natural occurrences indicate that certain additives, particularly PO 4 and Mg, stabilize MHC. Laboratory studies confirm that a small amount of PO 4 in solution (>30 μM) can significantly inhibit the transformation of MHC. MHC has a higher sorption capacity for PO 4 than calcite and aragonite. The modes of PO 4 uptake are adsorption on the MHC surface at moderate phosphate concentrations and precipitation of secondary calcium phosphate minerals at higher concentrations. Arsenate is most likely removed from the solution during the transformation of MHC. The proposed sorption mechanism of arsenate is coprecipitation during crystallization of aragonite. The arsenic sorption capacity by MHC is significantly higher than simple adsorption on calcite.

Monohydrocalcite: a promising remediation material for hazardous anions

NASA Astrophysics Data System (ADS)

Fukushi, Keisuke; Munemoto, Takashi; Sakai, Minoru; Yagi, Shintaro

2011-12-01

The formation conditions, solubility and stability of monohydrocalcite (MHC, CaCO3·H2O), as well as sorption behaviors of toxic anions on MHC, are reviewed to evaluate MHC as a remediation material for hazardous oxyanions. MHC is a rare mineral in geological settings that occurs in recent sediments in saline lakes. Water temperature does not seem to be an important factor for MHC formation. The pH of lake water is usually higher than 8 and the Mg/Ca ratio exceeds 4. MHC synthesis experiments as a function of time indicate that MHC is formed from amorphous calcium carbonate and transforms to calcite and/or aragonite. Most studies show that MHC forms from solutions containing Mg, which inhibits the formation of stable calcium carbonates. The solubility of MHC is higher than those of calcite, aragonite and vaterite, but lower than those of ikaite and amorphous calcium carbonate at ambient temperature. The solubility of MHC decreases with temperature. MHC is unstable and readily transforms to calcite or aragonite. The transformation consists of the dissolution of MHC and the subsequent formation of stable phases from the solution. The rate-limiting steps of the transformation of MHC are the nucleation and growth of stable crystalline phases. Natural occurrences indicate that certain additives, particularly PO4 and Mg, stabilize MHC. Laboratory studies confirm that a small amount of PO4 in solution (>30 μM) can significantly inhibit the transformation of MHC. MHC has a higher sorption capacity for PO4 than calcite and aragonite. The modes of PO4 uptake are adsorption on the MHC surface at moderate phosphate concentrations and precipitation of secondary calcium phosphate minerals at higher concentrations. Arsenate is most likely removed from the solution during the transformation of MHC. The proposed sorption mechanism of arsenate is coprecipitation during crystallization of aragonite. The arsenic sorption capacity by MHC is significantly higher than simple adsorption on calcite.

In vitro testing for genotoxicity of indigo naturalis assessed by micronucleus test.

PubMed

Dominici, Luca; Cerbone, Barbara; Villarini, Milena; Fatigoni, Cristina; Moretti, Massimo

2010-07-01

In the field of cosmetic dyes, used for coloring the hair and skin, there is a clear tendency to replace the widely used synthetic dyes by natural colorants, such as henna and mixtures of henna with indigo. The aim of this study was to estimate the genotoxicity of water and DMSO solutions of indigo naturalis (prepared from Indigofera tinctoria leaves) using the cytokinesis-blocked micronucleus (CBMN) assay in the human metabolically active HepG2 cell line. The cytotoxic effects of indigo solutions were first assessed by propidium iodide and fluorescein-diacetate simultaneous staining. For both solutions, cytotoxicity was always under 10%. Data obtained in the CBMN assay (for all concentrations tested) indicated that the frequency of MN (micronuclei) in exposed cells was no higher than the control. Both the water and DMSO solutions showed the same behavior. These results indicate that indigo naturalis exhibits neither cytotoxicity, nor genotoxicity for all concentrations tested, which may justify excluding indigofera and its components from the list of carcinogenic agents.

Information entropy to measure the spatial and temporal complexity of solute transport in heterogeneous porous media

NASA Astrophysics Data System (ADS)

Li, Weiyao; Huang, Guanhua; Xiong, Yunwu

2016-04-01

The complexity of the spatial structure of porous media, randomness of groundwater recharge and discharge (rainfall, runoff, etc.) has led to groundwater movement complexity, physical and chemical interaction between groundwater and porous media cause solute transport in the medium more complicated. An appropriate method to describe the complexity of features is essential when study on solute transport and conversion in porous media. Information entropy could measure uncertainty and disorder, therefore we attempted to investigate complexity, explore the contact between the information entropy and complexity of solute transport in heterogeneous porous media using information entropy theory. Based on Markov theory, two-dimensional stochastic field of hydraulic conductivity (K) was generated by transition probability. Flow and solute transport model were established under four conditions (instantaneous point source, continuous point source, instantaneous line source and continuous line source). The spatial and temporal complexity of solute transport process was characterized and evaluated using spatial moment and information entropy. Results indicated that the entropy increased as the increase of complexity of solute transport process. For the point source, the one-dimensional entropy of solute concentration increased at first and then decreased along X and Y directions. As time increased, entropy peak value basically unchanged, peak position migrated along the flow direction (X direction) and approximately coincided with the centroid position. With the increase of time, spatial variability and complexity of solute concentration increase, which result in the increases of the second-order spatial moment and the two-dimensional entropy. Information entropy of line source was higher than point source. Solute entropy obtained from continuous input was higher than instantaneous input. Due to the increase of average length of lithoface, media continuity increased, flow and solute transport complexity weakened, and the corresponding information entropy also decreased. Longitudinal macro dispersivity declined slightly at early time then rose. Solute spatial and temporal distribution had significant impacts on the information entropy. Information entropy could reflect the change of solute distribution. Information entropy appears a tool to characterize the spatial and temporal complexity of solute migration and provides a reference for future research.

Preparation of metallic nanoparticles by irradiation in starch aqueous solution

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

Nemţanu, Monica R., E-mail: monica.nemtanu@inflpr.ro; Braşoveanu, Mirela, E-mail: monica.nemtanu@inflpr.ro; Iacob, Nicuşor, E-mail: monica.nemtanu@inflpr.ro

Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔE{sub ab} (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle h{supmore » o} was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.« less

Reduction of the "burst release" of copper ions from copper-based intrauterine devices by organic inhibitors.

PubMed

Alvarez, Florencia; Schilardi, Patricia L; de Mele, Monica Fernández Lorenzo

2012-01-01

The copper intrauterine device is a contraceptive method that is based on the release of copper ions from a copper wire. Immediately after insertion, the dissolution of copper in the uterine fluid is markedly higher ("burst release") than that necessary for contraception action, leading to a variety of harmful effects. Pretreatments with organic compounds [thiourea (TU) and purine (PU), 10(-4)-10(-2) M concentration range, 1- and 3-h immersion times] were tested. The dissolution of copper with and without pretreatments in TU and PU solutions was analyzed by conventional electrochemical techniques and surface analysis. Pretreatments in PU solutions reduced the initial corrosion rate of copper in simulated uterine solutions, with inhibitory efficiencies that depend on the PU concentration and on the immersion time assayed. Inhibitory efficiency values higher than 98% for pretreatments with ≥10(-3) M PU were found. Conversely, after TU pretreatments, a high copper release was measured. It was concluded that 10(-3) M PU pretreatment is a promising strategy able to reduce the "burst release" of copper and to ensure contraceptive action. Copyright © 2012 Elsevier Inc. All rights reserved.

Photo-catalytic decolourisation of toxic dye with N-doped titania: a case study with Acid Blue 25.

PubMed

Chakrabortty, Dhruba; Gupta, Susmita Sen

2013-05-01

Dyes are one of the hazardous water pollutants. Toxic Acid Blue 25, an anthraquinonic dye, has been decolourised by photo-catalysing it with nitrogen doped titania in aqueous medium. The photo catalyst was prepared from 15% TiCl3 and 25% aqueous NH3 solution as precursor. XRD and TEM revealed the formation of well crystalline anatase phase having particle size in the nano-range. BET surface area of the sample was higher than that of pure anatase TiO2. DRS showed higher absorption of radiation in visible range compared to pure anatase TiO2. XPS revealed the presence of nitrogen in N-Ti-O environment. The experimental parameters, namely, photocatalyst dose, initial dye concentration as well as solution pH influence the decolourisation process. At pH 3.0, the N-TiO2 could decolourise almost 100% Acid Blue 25 within one hour. The influence of N-TiO2 dose, initial concentration of Acid Blue 25 and solution pH on adsorption-desorption equilibrium is also studied. The adsorption process follows Lagergren first order kinetics while the modified Langmuir-Hinselwood model is suitably fitted for photocatalytic decolourisation of Acid Blue 25.

Solar thermoelectric generator

DOEpatents

Toberer, Eric S.; Baranowski, Lauryn L.; Warren, Emily L.

2016-05-03

Solar thermoelectric generators (STEGs) are solid state heat engines that generate electricity from concentrated sunlight. A novel detailed balance model for STEGs is provided and applied to both state-of-the-art and idealized materials. STEGs can produce electricity by using sunlight to heat one side of a thermoelectric generator. While concentrated sunlight can be used to achieve extremely high temperatures (and thus improved generator efficiency), the solar absorber also emits a significant amount of black body radiation. This emitted light is the dominant loss mechanism in these generators. In this invention, we propose a solution to this problem that eliminates virtually all of the emitted black body radiation. This enables solar thermoelectric generators to operate at higher efficiency and achieve said efficient with lower levels of optical concentration. The solution is suitable for both single and dual axis solar thermoelectric generators.

DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels

PubMed Central

Zinchenko, Anatoly; Taki, Yosuke; Sergeyev, Vladimir G.; Murata, Shizuaki

2015-01-01

A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed. PMID:28347011

DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels.

PubMed

Zinchenko, Anatoly; Taki, Yosuke; Sergeyev, Vladimir G; Murata, Shizuaki

2015-03-03

A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed.

Calcium ion binding to a soil fulvic acid using a donnan potential model

USGS Publications Warehouse

Marinsky, J.A.; Mathuthu, A.; Ephraim, J.H.; Reddy, M.M.

1999-01-01

Calcium ion binding to a soil fulvic acid (Armadale Bh Horizon) was evaluated over a range of calcium ion concentrations, from pH 3.8 to 7.3, using potentiometric titrations and calcium ion electrode measurements. Fulvic acid concentration was constant (100 milligrams per liter) and calcium ion concentration varied up to 8 X 10-4 moles per liter. Experiments discussed here included: (1) titrations of fulvic acid-calcium ion containing solutions with sodium hydroxide; and (2) titrations of fully neutralized fulvic acid with calcium chloride solutions. Apparent binding constants (expressed as the logarithm of the value, log ??app) vary with solution pH, calcium ion concentration, degree of acid dissociation, and ionic strength (from log ??app = 2.5 to 3.9) and are similar to those reported by others. Fulvic acid charge, and the associated Donnan Potential, influences calcium ion-fulvic acid ion pair formation. A Donnan Potential corrrection term allowed calculation of intrinsic calcium ion-fulvic acid binding constants. Intrinsic binding constants vary from 1.2 to 2.5 (the average value is about log??= 1.6) and are similar to, but somewhat higher than, stability constants for calcium ion-carboxylic acid monodentate complexes. ?? by Oldenbourg Wissenschaftsverlag, Mu??nchen.

Nanometric Surface Oscillation Spectroscopy of Water-Poor Microemulsions.

PubMed

Corti, Mario; Raudino, Antonio; Cantù, Laura; Theisen, Johannes; Pleines, Maximilian; Zemb, Thomas N

2018-06-18

Selectively exchanging metal complexes between emulsified water-poor microemulsions and concentrated solutions of mixed electrolytes is the core technology for strategic metal recycling. Nanostructuration triggered by solutes present in the organic phase is understood, but little is known about fluctuations of the microemulsion-water interface. We use here a modified version of an opto-electric device initially designed for air bubbles, in order to evidence resonant electrically induced surface waves of an oily droplet suspended in an aqueous phase. Resonant waves of nanometer amplitude of a millimeter-sized microemulsion droplet containing a common ion-specific extractant diluted by dodecane and suspended in a solution of rare earth nitrate are evidenced for the first time with low excitation fields (5 V/cm). From variation of the surface wave spectrum with rare earth concentration, we evidence up-take of rare-earth ions at the interface and at higher concentration the formation of a thin "crust" of liquid crystal forming at unusually low concentration, indicative of a surface induced phase transition. The effect of the liquid crystal structure on the resonance spectrum is backed up by a model, which is used to estimate crust thickness.

Effect of povidone-iodine addition on the corrosion behavior of cp-Ti in normal saline.

PubMed

Bhola, Rahul; Bhola, Shaily M; Mishra, Brajendra; Olson, David L

2010-05-01

The effect of various concentrations of povidone-iodine (PI) on the corrosion behavior of a commercially pure titanium alloy (Ti-1) has been investigated in normal saline solution to simulate the povidone-iodine addition in an oral environment. The open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements have been used to characterize the electrochemical phenomena occurring on the alloy surface. The open circuit potential values for Ti-1 in various concentrations of PI shift considerably towards noble direction as compared to pure normal saline. In the potentiodynamic polarization curve for Ti-1 in various solutions, the cathodic current density has increased for all concentrations of PI and the anodic current density has decreased. Only the 0.1% PI concentration is able to inhibit corrosion of Ti-1 in normal saline and the other higher concentrations studied, accelerate corrosion. The EIS data for Ti-1 in normal saline and in various concentrations of PI follows a one time constant circuit, suggesting the formation of a single passive film on Ti-1 which is not altered by the addition of PI to normal saline.

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.

Effects of sodium chloride salting and substitution with potassium chloride on whey expulsion of Cheddar cheese.

PubMed

Lu, Y; McMahon, D J

2015-01-01

A challenge in manufacturing reduced-sodium cheese is that whey expulsion after salting decreases when less salt is applied. Our objectives were (1) to determine whether changing the salting method would increase whey syneresis when making a lower sodium cheese and (2) to better understand factors contributing to salt-induced curd syneresis. Unsalted milled Cheddar curds were salted using different salting intervals (5 or 10 min), different salting levels (20, 25, or 30g/kg), different numbers of applications when using only 20g/kg salt (1, 2, or 3 applications), and salting with the equivalent of 30g/kg NaCl using a 2:1 molar ratio of NaCl and KCl. Whey from these curds was collected every 5 or 10 min until 30 or 40 min after the start of salting, and curds were subsequently pressed for 3h. Additional trials were conducted in which salted milled Cheddar cheese curd was immersed at 22°C for 6h in various solutions to determine how milled curd pieces respond to different levels of salt and Ca. The use of 10-min intervals delayed whey syneresis without influencing total whey expulsion or cheese composition after pressing. Lowering the salt level reduced whey expulsion, resulting in cheeses with higher moisture and slightly lower pH. Adding salt faster did not increase whey expulsion in reduced-salt cheese. Partial substitution with KCl restored the extent of whey expulsion. When salted milled curd was immersed in a 30g/L salt solution, there was a net influx of salt solution into the curd and curd weight increased. When curd was immersed in 60g/L salt solution, a contraction of curd occurred. Curd shrinkage was more pronounced as the salt solution concentration was increased to 90 and 120g/L. Increasing the Ca concentration in test solutions (such that both serum and total Ca in the curd increased) also promoted curd contraction, resulting in lower curd moisture and pH and less weight gain by the curd. The proportion of Ca in the curd that was bound to the para-casein protein matrix changed with the Ca content of the test solution. Compared with test solutions containing 10g/L Ca, at low Ca levels (i.e., 1 and 5g/L) the proportion of bound Ca was lower, whereas at 20g/L Ca, the proportion of bound Ca was higher. Both Ca and salt concentration influence the physicochemical properties of the protein matrix such that at low concentrations the curd expands, whereas at high concentrations the curd contracts and expels whey. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Ion Relations of Symplastic and Apoplastic Space in Leaves from Spinacia oleracea L. and Pisum sativum L. under Salinity 1

PubMed Central

Speer, Michael; Kaiser, Werner M.

1991-01-01

Salt tolerant spinach (Spinacia oleracea) and salt sensitive pea (Pisum sativum) plants were exposed to mild salinity under identical growth conditions. In order to compare the ability of the two species for extra- and intracellular solute compartmentation in leaves, various solutes were determined in intercellular washing fluids and in aqueously isolated intact chloroplasts. In pea plants exposed to 100 millimolar NaCl for 14 days, apoplastic salt concentrations in leaflets increased continuously with time up to 204 (Cl−) and 87 millimolar (Na+), whereas the two ions reached a steady concentration of only 13 and 7 millimolar, respectively, in spinach leaves. In isolated intact chloroplasts from both species, sodium concentrations were not much different, but chloride concentrations were significantly higher in pea than in spinach. Together with data from whole leaf extracts, these measurements permitted an estimation of apoplastic, cytoplasmic, and vacuolar solute concentrations. Sodium and chloride concentration gradients across the tonoplast were rather similar in both species, but spinach was able to maintain much steeper sodium gradients across the plasmamembrane compared with peas. Between day 12 and day 17, concentrations of other inorganic ions in the pea leaf apoplast increased abruptly, indicating the onset of cell disintegration. It is concluded that the differential salt sensitivity of pea and spinach cannot be traced back to a single plant performance. Major differences appear to be the inability of pea to control salt accumulation in the shoot, to maintain steep ion gradients across the leaf cell plasmalemma, and to synthesize compatible solutes. Perhaps less important is a lower selectivity of pea for K+/Na+ and NO3−/Cl− uptake by roots. PMID:16668541

Aqueous penetration and biological activity of moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% solution in cataract surgery patients.

PubMed

Kim, Dianne H; Stark, Walter J; O'Brien, Terrence P; Dick, James D

2005-11-01

To measure the achievable perioperative aqueous concentration of the commercially available topically administered fourth generation fluoroquinolones, moxifloxacin 0.5% ophthalmic solution, and gatifloxacin 0.3% ophthalmic solution, and to correlate this concentration with the agents' biological efficacy in the aqueous humor of patients undergoing routine cataract surgery. Prospective, randomized, parallel, double-masked, clinical trial. Fifty patients undergoing cataract extraction. Patients (n = 25) were given perioperative topical moxifloxacin 0.5% or topical gatifloxacin 0.3% (n = 25). One drop of antibiotic was administered every 10 minutes for 4 doses beginning 1 hour prior to surgery. Aqueous humor was sampled via paracentesis and antibiotic concentrations were determined using validated high performance liquid chromatography (HPLC) procedures. Dilution analyses were performed to determine the biological efficacy of the agents in the aqueous against Staphylococcus epidermidis, the most common cause of postcataract endophthalmitis. Aqueous humor antibiotic concentrations were measured using HPLC and microdilution bioassay techniques. Biological activity was measured as minimal inhibitory dilution and minimal bactericidal dilution. Aqueous humor concentrations for moxifloxacin via HPLC analysis were 1.80 (+/-1.21) microg/ml, whereas those for gatifloxacin were 0.48 (+/-0.34) microg/ml. This 3.8-fold difference in aqueous humor antibiotic concentrations was statistically significant (P = 0.00003). Similarly, the biological dilution analysis of the aqueous humor samples showed that moxifloxacin attained an estimated activity of 2.1 microg/ml, whereas the gatifloxacin activity was approximately 0.4 mug/ml, which represented a 4.9-fold difference. This study demonstrated that after topically administered perioperative antibiotics with cataract surgery, moxifloxacin 0.5% ophthalmic solution achieved a statistically significantly higher concentration in aqueous humor compared with gatifloxacin (P = 0.00003). Results from the broth dilution analysis showed that moxifloxacin 0.5% was biologically more active against S. epidermidis than gatifloxacin 0.3% in aqueous humor after topical application. There were no adverse events reported, and incision wounds healed quickly and as expected.

Dual permeability modeling of tile drain management influences on hydrologic and nutrient transport characteristics in macroporous soil

NASA Astrophysics Data System (ADS)

Frey, Steven K.; Hwang, Hyoun-Tae; Park, Young-Jin; Hussain, Syed I.; Gottschall, Natalie; Edwards, Mark; Lapen, David R.

2016-04-01

Tile drainage management is considered a beneficial management practice (BMP) for reducing nutrient loads in surface water. In this study, 2-dimensional dual permeability models were developed to simulate flow and transport following liquid swine manure and rhodamine WT (strongly sorbing) tracer application on macroporous clay loam soils under controlled (CD) and free drainage (FD) tile management. Dominant flow and transport characteristics were successfully replicated, including higher and more continuous tile discharge and lower peak rhodamine WT concentrations in FD tile effluent; in relation to CD, where discharge was intermittent, peak rhodamine concentrations higher, and mass exchange from macropores into the soil matrix greater. Explicit representation of preferential flow was essential, as macropores transmitted >98% of surface infiltration, tile flow, and tile solute loads for both FD and CD. Incorporating an active 3rd type lower boundary condition that facilitated groundwater interaction was imperative for simulating CD, as the higher (relative to FD) water table enhanced water and soluble nutrient movement from the soil profile into deeper groundwater. Scenario analysis revealed that in conditions where slight upwards hydraulic gradients exist beneath tiles, groundwater upwelling can influence the concentration of surface derived solutes in tile effluent under FD conditions; whereas the higher and flatter CD water table can restrict groundwater upwelling. Results show that while CD can reduce tile discharge, it can also lead to an increase in surface-application derived nutrient concentrations in tile effluent and hence surface water receptors, and it can promote NO3 loading into groundwater. This study demonstrates dual permeability modeling as a tool for increasing the conceptual understanding of tile drainage BMPs.

Chemically reactive species in squeezed flow through modified Fourier's and Fick's laws

NASA Astrophysics Data System (ADS)

Farooq, M.; Ahmad, S.; Javed, M.; Anjum, Aisha

2018-02-01

The squeezing flow of a Newtonian fluid with variable viscosity over a stretchable sheet embedded in Darcy porous medium is addressed. Cattaneo-Christov double diffusion models are adopted to disclose the salient features of heat and mass transport via variable thermal conductivity and variable mass diffusivity instead of conventional Fourier's and Fick's laws. Further, the concept of heat generation/absorption coefficient and first-order chemical reaction are also imposed to illustrate the characteristics of heat and mass transfer. Highly nonlinear computations are developed in dimensionless form and analyzed via the homotopic technique. The variation of flow parameters on velocity, concentration, and temperature distributions are sketched and disclosed physically. The results found that both concentration and temperature distributions decay for higher solutal and thermal relaxation parameters, respectively. Moreover, a higher chemical reaction parameter results in the reduction of the concentration field whereas the temperature profile enhances for a higher heat generation/absorption parameter.

Measurements and theoretical interpretation of points of zero charge/potential of BSA protein.

PubMed

Salis, Andrea; Boström, Mathias; Medda, Luca; Cugia, Francesca; Barse, Brajesh; Parsons, Drew F; Ninham, Barry W; Monduzzi, Maura

2011-09-20

The points of zero charge/potential of proteins depend not only on pH but also on how they are measured. They depend also on background salt solution type and concentration. The protein isoelectric point (IEP) is determined by electrokinetical measurements, whereas the isoionic point (IIP) is determined by potentiometric titrations. Here we use potentiometric titration and zeta potential (ζ) measurements at different NaCl concentrations to study systematically the effect of ionic strength on the IEP and IIP of bovine serum albumin (BSA) aqueous solutions. It is found that high ionic strengths produce a shift of both points toward lower (IEP) and higher (IIP) pH values. This result was already reported more than 60 years ago. At that time, the only available theory was the purely electrostatic Debye-Hückel theory. It was not able to predict the opposite trends of IIP and IEP with ionic strength increase. Here, we extend that theory to admit both electrostatic and nonelectrostatic (NES) dispersion interactions. The use of a modified Poisson-Boltzmann equation for a simple model system (a charge regulated spherical colloidal particle in NaCl salt solutions), that includes these ion specific interactions, allows us to explain the opposite trends observed for isoelectric point (zero zeta potential) and isoionic point (zero protein charge) of BSA. At higher concentrations, an excess of the anion (with stronger NES interactions than the cation) is adsorbed at the surface due to an attractive ionic NES potential. This makes the potential relatively more negative. Consequently, the IEP is pushed toward lower pH. But the charge regulation condition means that the surface charge becomes relatively more positive as the surface potential becomes more negative. Consequently, the IIP (measuring charge) shifts toward higher pH as concentration increases, in the opposite direction from the IEP (measuring potential). © 2011 American Chemical Society

SFG study of the ethanol in an acidic medium--Pt(110) interface: effects of the alcohol concentration.

PubMed

Gomes, Janaina F; Busson, Bertrand; Tadjeddine, Abderrahmane

2006-03-23

Ethanol in an acidic solution-Pt(110) interface was studied by SFG spectroscopy (between 1820 and 2325 cm(-1)) to explore primarily the effects of the alcohol concentration. Stretching bands of H-Pt (ca. 1970 or 2050 cm(-1)) and CO (ca. 1980 and 2040 cm(-1)) species, produced by the ethanol oxidation, were detected during the adsorption and oxidation of 0-1 mol L(-1) ethanol in a 0.1 mol L(-1) HClO(4) solution on the electrode surface. Hydrogen and CO coadsorb stably on Pt(110) between 0.05 and 0.15 V in ethanol-containing solutions. In this potential range, the blue shift of the hydrogen resonance (ca. 80 cm(-1)) reveals a weakening of the hydrogen bonding between adsorbed hydrogen and water molecules in the double layer. After the hydrogen desorption (0.15 V), the formation of compact CO islands, depending on the ethanol concentration, lifts the Pt(110) surface reconstruction. In ethanol-free solution, the surface remains reconstructed. The lower-frequency CO band is assigned to the CO species adsorbed on (1 x 2) reconstructed Pt(110) domains, having smaller local coverages, while the higher-frequency CO band is attributed to the close-packed CO species adsorbed on (1 x 1) patches. The reaction pathway forming CO(2) is less favored with increasing ethanol concentration.

Degradation of sulfamethazine by gamma irradiation in the presence of hydrogen peroxide.

PubMed

Liu, Yuankun; Wang, Jianlong

2013-04-15

The gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated. The initial SMT concentration was 20mg/L and it was irradiated in the presence of extra H2O2 with initial concentration of 0, 10 and 30 mg/L. The results showed that gamma irradiation was effective for removing SMT in aqueous solution and its degradation conformed to the pseudo first-order kinetics under the applied conditions. When initial H2O2 concentration was in the range of 0-30 mg/L, higher concentration of H2O2 was more effective for the decomposition and mineralization of SMT. However, the removal of total organic carbon (TOC) was not as effective as that of SMT. Total nitrogen (TN) was not removed even at absorbed dose of 5 kGy, which was highest dose applied in this study. Major decomposition products of SMT, including degradation intermediates, organic acids and some inorganic ions were detected by high performance liquid chromatography (HPLC) and ion chromatography (IC). Sulfate (SO4(2-)), formic acid (HCOOH), acetic acid (CH3COOH), 4-aminophenol, 4-nitrophenol were identified in the irradiated solutions. Possible pathways for SMT decomposition by gamma irradiation in aqueous solution were proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Nanofiltration properties of PTMSP in binary organic solvents mixtures

NASA Astrophysics Data System (ADS)

Yushkin, A. A.; Kossov, A. A.; Volkov, V. V.

2016-09-01

In this study, the stability and nanofiltration performance of poly[1-(trimethylsilyl)- 1-propyne] (PTMSP) in ethanol solutions of butylaldehyde, 1-decanal, 1-hexene, 1-decene was evaluated. It was found that PTMSP was insoluble in all aldehyde solutions, but it was soluble at olefin concentration of 80% or higher. Nanofiltration experiments demonstrate that binary mixtures of 1-decanal and ethanol viscosity are not the parameter affecting on membrane permeability and rejection of solute as well as swelling degree. In the case of decanol/ethanol solutions both solution viscosity and molar volume demonstrate the best fit of experimental data. It was shown that with the decrease of ethanol content in the feed, the rejection of anionic solute Remazol Brilliant Blue R (MW 626) increases from 94 up to 97%.

PROCESSING OF MONAZITE SAND

DOEpatents

Calkins, G.D.; Bohlmann, E.G.

1957-12-01

A process for the recovery of thorium, uranium, and rare earths from monazite sands is presented. The sands are first digested and dissolved in concentrated NaOH, and the solution is then diluted causing precipitation of uranium, thorium and rare earth hydroxides. The precipitate is collected and dissolved in HCl, and the pH of this solution is adjusted to about 6, precipitating the hydroxides of thorium and uranium but leaving the rare earths in solution. The rare earths are then separated from the solution by precipitation at a still higher pH. The thorium and uranium containing precipitate is redissolved in HNO/sub 3/ and the two elements are separated by extraction into tributyl phosphate and back extraction with a weakly acidic solution to remove the thorium.

The effect of minimal concentration of ethylene glycol (EG) combined with polyvinylpyrrolidone (PVP) on mouse oocyte survival and subsequent embryonic development following vitrification.

PubMed

Wang, Yao; Okitsu, Osamu; Zhao, Xiao-Ming; Sun, Yun; Di, Wen; Chian, Ri-Cheng

2014-01-01

Vitrification techniques employ a relatively high concentration of cryoprotectant in vitrification solutions. Exposure of oocytes to high concentrations of cryoprotectant is known to damage the oocytes via both cytotoxic and osmotic effects. Therefore, the key to successful vitrification of oocytes is to strike a balance between the usage of minimal concentration of cryoprotectant without compromising their cryoprotective actions. The minimal concentration of ethylene glycol (EG) on mouse oocyte survival and subsequent embryonic development was evaluated following vitrification-warming and parthenogenetic activation. Polyvinylpyrrolidone (PVP) combined with EG on mouse oocyte survival and subsequent embryonic development as well as morphology of the spindle and chromosome alignment were also evaluated. Vitrification system was adapted with JY Straw and the cooling rate was approximately 442-500 °C/min. In contrast, the warming rate was approximately 2,210-2,652 °C/min. Survival rate of oocytes increased significantly when 15 % EG was combined with 2 % PVP in vitrification solution (VS). The effect of combination of EG and PVP was not significant when the concentration of EG was 20 % and higher. Although there were no significant differences in embryonic development, the percentage of abnormal spindle and chromosome alignment was significantly higher in the oocytes without 2 % PVP in VS. Our data provide a proof of principle for oocyte vitrification that may not require a high concentration of cryoprotectant. There are synergic effects of EG combined with PVP for oocyte vitrification, which may provide important information to the field in developing less cytotoxic VS.

Phosphorus sorption capacity of biochars varies with biochar type and salinity level.

PubMed

Dugdug, Abdelhafid Ahmed; Chang, Scott X; Ok, Yong Sik; Rajapaksha, Anushka Upamali; Anyia, Anthony

2018-02-10

Biochar is recognized as an effective material for recovering excess nutrients, including phosphorus (P), from aqueous solutions. Practically, that benefits the environment through reducing P losses from biochar-amended soils; however, how salinity influences P sorption by biochar is poorly understood and there has been no direct comparison on P sorption capacity between biochars derived from different feedstock types under non-saline and saline conditions. In this study, biochars derived from wheat straw, hardwood, and willow wood were used to compare P sorption at three levels of electrical conductivity (EC) (0, 4, and 8 dS m -1 ) to represent a wide range of salinity conditions. Phosphorus sorption by wheat straw and hardwood biochars increased as aqueous solution P concentration increased, with willow wood biochar exhibiting an opposite trend for P sorption. However, the pattern for P sorption became the same as the other biochars after the willow wood biochar was de-ashed with 1 M HCl and 0.05 M HF. Willow wood biochar had the highest P sorption (1.93 mg g -1 ) followed by hardwood (1.20 mg g -1 ) and wheat straw biochars (1.06 mg g -1 ) in a 25 mg L -1 P solution. Although the pH in the equilibrium solution was higher with willow wood biochar (~ 9.5) than with the other two biochars (~ 6.5), solution pH had no or minor effects on P sorption by willow wood biochar. The high sorption rate of P by willow wood biochar could be attributed to the higher concentrations of salt and other elements (i.e., Ca and Mg) in the biochar in comparison to that in wheat straw and hardwood biochars; the EC values were 2.27, 0.53, and 0.27 dS m -1 for willow wood, wheat straw, and hardwood biochars, respectively. A portion of P desorbed from the willow wood biochar; and that desorption increased with the decreasing P concentration in the aqueous solution. Salinity in the aqueous solution influenced P sorption by hardwood and willow wood but not by wheat straw biochar. We conclude that the P sorption capacity of the studied biochars is dependent on the concentration of the soluble element in the biochar, which is dependent on the biochar type, as well as the salinity level in the aqueous solution.

Combination of surfactant solubilization with permanganate oxidation for DNAPL remediation.

PubMed

Li, Zhaohui; Hanlie, Hong

2008-02-01

A combination of surfactant solubilization with permanganate oxidation of trichloroethylene (TCE) was studied in batch, flow-through column, and three-dimensional (3-D) tank tests. Batch results showed that chloride production, an indication of TCE degradation, followed a pseudo-first-order reaction kinetics with respect to KMnO4 in the presence of free-phase TCE. A higher chloride production rate was achieved when anionic surfactants were present. The observed pseudo-first-order reaction rate constant increased as the concentrations of anionic surfactants Ninate 411 and Calfax increased from 0% to 0.1%, 0.3%, and 1.0%. Column experiments on TCE reduction by permanganate in the presence and absence of surfactants were carried out using well-sorted coarse Ottawa sand. The peak effluent TCE concentration reached 1700 mg/L due to enhanced solubilization when both sodium dodecyl sulfate (SDS) and permanganate were used, in contrast to less than 300 mg/L when only permanganate solution was used. In addition, the effluent TCE concentration decreased much faster when SDS was present in the permanganate solution, compared with the case when SDS was absent. With an initial 1 mL of TCE emplaced in the columns, the effluent TCE concentration dropped to <5mg/L after 29-31h of flushing with 1% SDS and 0.1% KMnO4 solution in contrast to 37-73 h when only 0.1% KMnO4 was used. Furthermore, KMnO4 breakthrough occurred after 21-25 h of injection when SDS was present compared with 45-70 h later when SDS was absent. A slightly higher chloride concentration was observed in the earlier stage of the column experiment and the chloride concentration decreased quickly once KMnO4 was seen in the effluent. The 3-D tank test showed that the MnO2 precipitation front formed more quickly when 1% SDS was present, which further confirmed the observation from the column study.

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, Robin; Horwitz, E. Philip; Bond, Andrew H.

1998-01-01

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution.

Improved retroreflection method for measuring the refractive index of liquids.

PubMed

Shao, Duo; Tian, Linghao; Chen, Jingfei; Chen, Xianfeng

2010-06-01

We propose a new method for measuring the refractive index of liquids with high precision; the method is based on use of the optical fiber end face. As an example, we investigated the refractive index of sugar solution under varying conditions tens of times. The results show that this method has the advantage of higher stability and repeatability. The concentration and the temperature-dependent refractive index of the sugar solution is also experimentally studied.

Reversible Hydrogel–Solution System of Silk with High Beta-Sheet Content

PubMed Central

2015-01-01

Silkworm silk has been widely used as a textile fiber, as biomaterials and in optically functional materials due to its extraordinary properties. The β-sheet-rich natural nanofiber units of about 10–50 nm in diameter are often considered the origin of these properties, yet it remains unclear how silk self-assembles into these hierarchical structures. A new system composed of β-sheet-rich silk nanofibers about 10–20 nm in diameter is reported here, where these nanofibers formed into “flowing hydrogels” at 0.5–2% solutions and could be transformed back into the solution state at lower concentrations, even with a high β-sheet content. This is in contrast with other silk processed materials, where significant β-sheet content negates reversibility between solution and solid states. These fibers are formed by regulating the self-assembly process of silk in aqueous solution, which changes the distribution of negative charges while still supporting β-sheet formation in the structures. Mechanistically, there appears to be a shift toward negative charges along the outside of the silk nanofibers in our present study, resulting in a higher zeta potential (above −50 mV) than previous silk materials which tend to be below −30 mV. The higher negative charge on silk nanofibers resulted in electrostatic repulsion strong enough to negate further assembly of the nanofibers. Changing silk concentration changed the balance between hydrophobic interactions and electrostatic repulsion of β-sheet-rich silk nanofibers, resulting in reversible hydrogel–solution transitions. Furthermore, the silk nanofibers could be disassembled into shorter fibers and even nanoparticles upon ultrasonic treatment following the transition from hydrogel to solution due to the increased dispersion of hydrophobic smaller particles, without the loss of β-sheet content, and with retention of the ability to transition between hydrogel and solution states through reversion to longer nanofibers during self-assembly. These reversible solution-hydrogel transitions were tunable with ultrasonic intensity, time, or temperature. PMID:25056606

Reversible hydrogel-solution system of silk with high beta-sheet content.

PubMed

Bai, Shumeng; Zhang, Xiuli; Lu, Qiang; Sheng, Weiqin; Liu, Lijie; Dong, Boju; Kaplan, David L; Zhu, Hesun

2014-08-11

Silkworm silk has been widely used as a textile fiber, as biomaterials and in optically functional materials due to its extraordinary properties. The β-sheet-rich natural nanofiber units of about 10-50 nm in diameter are often considered the origin of these properties, yet it remains unclear how silk self-assembles into these hierarchical structures. A new system composed of β-sheet-rich silk nanofibers about 10-20 nm in diameter is reported here, where these nanofibers formed into "flowing hydrogels" at 0.5-2% solutions and could be transformed back into the solution state at lower concentrations, even with a high β-sheet content. This is in contrast with other silk processed materials, where significant β-sheet content negates reversibility between solution and solid states. These fibers are formed by regulating the self-assembly process of silk in aqueous solution, which changes the distribution of negative charges while still supporting β-sheet formation in the structures. Mechanistically, there appears to be a shift toward negative charges along the outside of the silk nanofibers in our present study, resulting in a higher zeta potential (above -50 mV) than previous silk materials which tend to be below -30 mV. The higher negative charge on silk nanofibers resulted in electrostatic repulsion strong enough to negate further assembly of the nanofibers. Changing silk concentration changed the balance between hydrophobic interactions and electrostatic repulsion of β-sheet-rich silk nanofibers, resulting in reversible hydrogel-solution transitions. Furthermore, the silk nanofibers could be disassembled into shorter fibers and even nanoparticles upon ultrasonic treatment following the transition from hydrogel to solution due to the increased dispersion of hydrophobic smaller particles, without the loss of β-sheet content, and with retention of the ability to transition between hydrogel and solution states through reversion to longer nanofibers during self-assembly. These reversible solution-hydrogel transitions were tunable with ultrasonic intensity, time, or temperature.

Influence of albumin on the electrochemical behaviour of Zr in phosphate buffered saline solutions.

PubMed

Wang, Lu-Ning; Huang, Xian-Qiu; Shinbine, Alyssa; Luo, Jing-Li

2013-02-01

The corrosion behaviour of Zr in phosphate buffered saline (PBS) solutions with various concentrations (0-4 g L(-1)) of albumin was studied by electrochemical techniques and surface analysis. Addition of albumin to PBS solutions moved the open circuit potential (OCP) to less nobler direction. OCP, polarization resistance and impedance increased and the corrosion current decreased over immersion duration. At early stages of immersion, the resistance was increased with the concentration of albumin because of the high adsorption kinetics of albumin on metal. After the long term immersion, the resistance in PBS without albumin was higher than PBS with albumin owing to the anodic dissolution effect of albumin on metal. According to the analysis of effective capacitances, a normal distribution of time-constants was proposed to estimate the surface film on Zr. A corrosion mechanism of Zr in PBS with different albumin was proposed based on electrochemical analysis.

[Efficiency of photodecomposition of trace NDMA in water by UV irradiation].

PubMed

Xu, Bing-Bing; Chen, Zhong-Lin; Qi, Fei; Ma, Jun

2008-07-01

Efficiency of photodecomposition of trace NDMA by UV irradiation was investigated with analyzing the initial concentration of NDMA, solution pH, irradiation area, irradiation intensity and water quality effect on NDMA photolysis. NDMA could be effectively photodegraded by UV irradiation. The removal efficiency of NDMA was 97.5% after 5 min of UV irradiation. Effect of initial NDMA concentration on photodecomposition of NDMA was not remarkable. With pH value ascending, the removal rate of NDMA photodecomposition decreased. The yields of photoquantum were more under lower solution pH than that under higher pH. NDMA had fastest reaction rate at solution pH = 2.2. Removal efficiency of NDMA increased with the available irradiation area ascending. Increscent ultraviolet irradiation intensity was good for NDMA degradation. Water quality affected the removal of NDMA slightly. The removal efficiency of NDMA in tap water and Songhua River raw water were 96.7% and 94.8%, respectively.

Improved electrical conductivity of poly(ethylene oxide) nanofibers using multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Lee, J. Y.; Kang, T.-H.; Choi, J. H.; Choi, I.-S.; Yu, W.-R.

2018-03-01

Highly conductive nanofibers with 1570 S/m were obtained from an electrospun solution of polymer containing multiwalled carbon nanotubes (MWCNTs). Homogeneous dispersion of high concentrations of MWCNTs was achieved by attaching poly(styrenesulfonic acid graft aniline) (PSS-g-ANI), an amphiphilic surfactant, to the MWCNT surface. The hydrophilic sulfonic acid group facilitated the dissolution of PSS-g-ANI-grafted MWCNTs in a polyethylene oxide (PEO) solution up to 6.7 wt% MWCNT. To our knowledge, this is the highest level of MWCNT doping attained in a solution designed for electrospinning. With the incorporation of PSS-g-ANI, the concentration of MWCNTs embedded in the electrospun nanofibers increased. More importantly, the alignment of MWCNTs along the nanofiber axis increased significantly, as confirmed by observed birefringence under crossed polarizers. The combination of higher doping levels and better alignment afforded highly conductive nanofibers suitable for electronic nanodevices.

Osmotic phenomena in application for hyperbaric oxygen treatment.

PubMed

Babchin, A; Levich, E; Melamed M D, Y; Sivashinsky, G

2011-03-01

Hyperbaric oxygen (HBO) treatment defines the medical procedure when the patient inhales pure oxygen at elevated pressure conditions. Many diseases and all injuries are associated with a lack of oxygen in tissues, known as hypoxia. HBO provides an effective method for fast oxygen delivery in medical practice. The exact mechanism of the oxygen transport under HBO conditions is not fully identified. The objective of this article is to extend the colloid and surface science basis for the oxygen transport in HBO conditions beyond the molecular diffusion transport mechanism. At a pressure in the hyperbaric chamber of two atmospheres, the partial pressure of oxygen in the blood plasma increases 10 times. The sharp increase of oxygen concentration in the blood plasma creates a considerable concentration gradient between the oxygen dissolved in the plasma and in the tissue. The concentration gradient of oxygen as a non-electrolyte solute causes an osmotic flow of blood plasma with dissolved oxygen. In other words, the molecular diffusion transport of oxygen is supplemented by the convective diffusion raised due to the osmotic flow, accelerating the oxygen delivery from blood to tissue. A non steady state equation for non-electrolyte osmosis is solved asymptotically. The solution clearly demonstrates two modes of osmotic flow: normal osmosis, directed from lower to higher solute concentrations, and anomalous osmosis, directed from higher to lower solute concentrations. The fast delivery of oxygen from blood to tissue is explained on the basis of the strong molecular interaction between the oxygen and the tissue, causing an influx of oxygen into the tissue by convective diffusion in the anomalous osmosis process. The transport of the second gas, nitrogen, dissolved in the blood plasma, is also taken into the consideration. As the patient does not inhale nitrogen during HBO treatment, but exhales it along with oxygen and carbon dioxide, the concentration of nitrogen in blood plasma drops and the nitrogen concentration gradient becomes directed from blood to tissue. On the assumption of weak interaction between the inert nitrogen and the human tissue, normal osmosis for the nitrogen transport takes place. Thus, the directions of anomalous osmotic flow caused by the oxygen concentration gradient coincide with the directions of normal osmotic flow, caused by the nitrogen concentration gradient. This leads to the conclusion that the presence of nitrogen in the human body promotes the oxygen delivery under HBO conditions, rendering the overall success of the hyperbaric oxygen treatment procedure. 2010 Elsevier B.V. All rights reserved.

Association of polymorphisms in solute carrier family 27, isoform A6 (SLC27A6) and fatty acid-binding protein-3 and fatty acid-binding protein-4 (FABP3 and FABP4) with fatty acid composition of bovine milk.

PubMed

Nafikov, R A; Schoonmaker, J P; Korn, K T; Noack, K; Garrick, D J; Koehler, K J; Minick-Bormann, J; Reecy, J M; Spurlock, D E; Beitz, D C

2013-09-01

The main goal of this study was to develop tools for genetic selection of animals producing milk with a lower concentration of saturated fatty acids (SFA) and a higher concentration of unsaturated fatty acids (UFA). The reasons for changing milk fatty acid (FA) composition were to improve milk technological properties, such as for production of more spreadable butter, and milk nutritional value with respect to the potentially adverse effects of SFA on human health. We hypothesized that genetic polymorphisms in solute carrier family 27, isoform A6 (SLC27A6) fatty acid transport protein gene and fatty acid binding protein (FABP)-3 and FABP-4 (FABP3 and FABP4) would affect the selectivity of FA uptake into, and FA redistribution inside, mammary epithelial cells, resulting in altered FA composition of bovine milk. The objectives of our study were to discover genetic polymorphisms in SLC27A6, FABP3, and FABP4, and to test those polymorphisms for associations with milk FA composition. The results showed that after pairwise comparisons between SLC27A6 haplotypes for significantly associated traits, haplotype H3 was significantly associated with 1.37 weight percentage (wt%) lower SFA concentration, 0.091 lower SFA:UFA ratio, and 0.17 wt% lower lauric acid (12:0) concentration, but 1.37 wt% higher UFA and 1.24 wt% higher monounsaturated fatty acid (MUFA) concentrations compared with haplotype H1 during the first 3 mo of lactation. Pairwise comparisons between FABP4 haplotypes for significantly associated traits showed that haplotype H3 was significantly associated with 1.04 wt% lower SFA concentration, 0.079 lower SFA:UFA ratio, 0.15 wt% lower lauric acid (12:0), and 0.27 wt% lower myristic acid (14:0) concentrations, but 1.04 wt% higher UFA and 0.91 wt% higher MUFA concentrations compared with haplotype H1 during the first 3 mo of lactation. Percentages of genetic variance explained by H3 versus H1 haplotype substitutions for SLC27A6 and FABP4 ranged from 2.50 to 4.86% and from 4.91 to 7.22%, respectively. Tag single nucleotide polymorphisms were identified to distinguish haplotypes H3 of SLC27A6 and FABP4 from others encompassing each gene. We found no significant associations between FABP3 haplotypes and milk FA composition. In conclusion, polymorphisms in FABP4 and SLC27A6 can be used to select for cattle producing milk with lower concentrations of SFA and higher concentrations of UFA. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Experimental and Computational Investigation of the Effect of Hydrophobicity on Aggregation and Osteoinductive Potential of BMP-2-Derived Peptide in a Hydrogel Matrix

PubMed Central

Moeinzadeh, Seyedsina; Barati, Danial; Sarvestani, Samaneh K.; Karimi, Tahereh

2015-01-01

An attractive approach to reduce the undesired side effects of bone morphogenetic proteins (BMPs) in regenerative medicine is to use osteoinductive peptide sequences derived from BMPs. Although the structure and function of BMPs have been studied extensively, there is limited data on structure and activity of BMP-derived peptides immobilized in hydrogels. The objective of this work was to investigate the effect of concentration and hydrophobicity of the BMP-2 peptide, corresponding to residues 73–92 of the knuckle epitope of BMP-2 protein, on peptide aggregation and osteogenic differentiation of human mesenchymal stem cells encapsulated in a polyethylene glycol (PEG) hydrogel. The peptide hydrophobicity was varied by capping PEG chain ends with short lactide segments. The BMP-2 peptide with a positive index of hydrophobicity had a critical micelle concentration (CMC) and formed aggregates in aqueous solution. Based on simulation results, there was a slight increase in the concentration of free peptide in solution with 1000-fold increase in peptide concentration. The dose-osteogenic response curve of the BMP-2 peptide was in the 0.0005–0.005 mM range, and osteoinductive potential of the BMP-2 peptide was significantly less than that of BMP-2 protein even at 1000-fold higher concentrations, which was attributed to peptide aggregation. Further, the peptide or PEG-peptide aggregates had significantly higher interaction energy with the cell membrane compared with the free peptide, which led to a higher nonspecific interaction with the cell membrane and loss of osteoinductive potential. Conjugation of the BMP-2 peptide to PEG increased CMC and osteoinductive potential of the peptide whereas conjugation to lactide-capped PEG reduced CMC and osteoinductive potential of the peptide. Experimental and simulation results revealed that osteoinductive potential of the BMP-2 peptide is correlated with its CMC and the free peptide concentration in aqueous medium and not the total concentration. PMID:25051457

Reexamining protein–protein and protein–solvent interactions from Kirkwood-Buff analysis of light scattering in multi-component solutions

PubMed Central

Blanco, Marco A.; Sahin, Erinc; Li, Yi; Roberts, Christopher J.

2011-01-01

The classic analysis of Rayleigh light scattering (LS) is re-examined for multi-component protein solutions, within the context of Kirkwood-Buff (KB) theory as well as a more generalized canonical treatment. Significant differences arise when traditional treatments that approximate constant pressure and neglect concentration fluctuations in one or more (co)solvent∕co-solute species are compared with more rigorous treatments at constant volume and with all species free to fluctuate. For dilute solutions, it is shown that LS can be used to rigorously and unambiguously obtain values for the osmotic second virial coefficient (B22), in contrast with recent arguments regarding protein interactions deduced from LS experiments. For more concentrated solutions, it is shown that conventional analysis over(under)-estimates the magnitude of B22 for significantly repulsive(attractive) conditions, and that protein-protein KB integrals (G22) are the more relevant quantity obtainable from LS. Published data for α–chymotrypsinogen A and a series of monoclonal antibodies at different pH and salt concentrations are re-analyzed using traditional and new treatments. The results illustrate that while traditional analysis may be sufficient if one is interested in only the sign of B22 or G22, the quantitative values can be significantly in error. A simple approach is illustrated for determining whether protein concentration (c2) is sufficiently dilute for B22 to apply, and for correcting B22 values from traditional LS regression at higher c2 values. The apparent molecular weight M2, app obtained from LS is shown to generally not be equal to the true molecular weight, with the differences arising from a combination of protein-solute and protein-cosolute interactions that may, in principle, also be determined from LS. PMID:21682538

Single- and double-strand break formation in DNA irradiated in aqueous solution: dependence on dose and OH radical scavenger concentration

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

Siddiqi, M.A.; Bothe, E.

The yields of single- and double-strand breaks (SSB and DSB) in calf thymus DNA, after /sup 60/Co gamma irradiation in dilute aqueous solution, have been determined via molecular weight measurements using a low-angle laser light scattering technique. The irradiations were administered to N/sub 2/O-containing solutions of DNA in the absence and presence of oxygen and with different concentrations of the OH radical scavengers phenol, tertiary butanol, and methanol. OH radicals were found to produce SSB linearly with dose with a G value of 55 nmol J-1 and 54 nmol J-1 in deoxygenated and oxygenated solutions, respectively. DSB were formed accordingmore » to a linear-quadratic dose relationship and the G value of linearly formed DSB were GDSB alpha(r.t.) = 3.5 nmol J-1 in deoxygenated and 3.2 nmol J-1 in oxygenated solution. The ratio of GSSB/GDSB alpha(r.t.) = gamma of 19 +/- 6 was independent of the scavenger concentration in the case of tertiary butanol and methanol-containing solutions. GDSB alpha(r.t.) is interpreted to result from a radical site transferred from a sugar moiety of the cleaved strand to the complementary intact strand. This process of radical transfer and subsequent cleavage of the second strand occurs with a probability of about 6 +/- 2% in the presence of oxygen at all scavenger concentrations studied. These data on scavenging capacity on GDSB alpha(r.t.) suggest that the double-strand breakage produced via radical transfer remains higher than that resulting from direct effect, up to scavenging capacities of about 10(9) s-1.« less

Aqueous Humor Penetration and Biological Activity of Moxifloxacin 0.5% Ophthalmic Solution Alone or with Dexamethasone 0.1.

PubMed

Gomes, Rachel L R; Viana, Rodrigo Galvão; Melo, Luiz Alberto S; Cruz, Alessandro Carvalho; Suenaga, Eunice Mayumi; Kenyon, Kenneth R; Campos, Mauro

2017-03-01

To compare aqueous humor concentrations of topically applied moxifloxacin 0.5% ophthalmic solution alone or in combination with dexamethasone 0.1% and to correlate these concentrations with the minimum inhibitory concentrations (MICs) for common endophthalmitis-causing organisms. Sixty-eight patients undergoing routine phacoemulsification with intraocular lens implantation received either moxifloxacin 0.5% alone or moxifloxacin 0.5% combined with dexamethasone. For both groups, 1 drop of the test solution was instilled 4 times daily 1 day preoperatively and 1 drop 1 h preoperatively. An aqueous humor sample obtained immediately before paracentesis was submitted to high-performance liquid chromatography-tandem mass spectrometry to determine the moxifloxacin concentration. The mean concentrations of moxifloxacin were 986.6 ng/mL in the moxifloxacin with dexamethasone group and 741.3 ng/mL in the moxifloxacin group (P = 0.13). Moxifloxacin concentrations of all samples exceeded the MICs for Staphylococcus epidermidis, S. aureus, and Streptococcus pneumoniae. All samples in the moxifloxacin with dexamethasone group and 94% in the moxifloxacin group achieved the MIC for Enterococcus species. For quinolone-resistant S. aureus, the MIC was achieved in 29% in the moxifloxacin with dexamethasone group and 9% in the moxifloxacin group (P = 0.06). Aqueous humor moxifloxacin concentrations were higher when topically administrated in combination with dexamethasone compared to the moxifloxacin alone. However, this difference was not statistically significant. Nevertheless, the MICs of the most common pathogens associated with endophthalmitis were exceeded in both study groups.

Stabilized micelles of amphoteric polyurethane formed by thermoresponsive micellization in HCl aqueous solution.

PubMed

Qiao, Yong; Zhang, Shifeng; Lin, Ouya; Deng, Liandong; Dong, Anjie

2008-04-01

The thermoresponsive micellization behavior of amphoteric polyurethane (APU) was studied in HCl aqueous solution (pH 2.0) through light scattering, transmission electron microscopy, and fluorescent measurement. When APU concentration is high enough, nonreversible assembly of macromolecules can be observed with temperature decreasing from 25 to 4 degrees C. However, micelles reaching equilibrium at 4 degrees C can self-assemble reversibly in the temperature range of 4-55 degrees C. According to our research, we found it is the temperature sensitivity of the poly(propylene oxide) (PPO) segments that leads to the reassembly of APU at lower temperature. We proposed that core-shell-corona micelles ultimately form with hydrophobic core, PPO shell, and hydrophilic corona when temperature increases from 4 to 25 degrees C. This structure is very stable and does not change at higher temperatures (25-55 degrees C). That provides a new way to obtain stable micelles with small size and narrow size distribution at higher concentration of APU.

Localized CO2 corrosion of carbon steel with different microstructures in brine solutions with an imidazoline-based inhibitor

NASA Astrophysics Data System (ADS)

Zhang, Huan-huan; Pang, Xiaolu; Gao, Kewei

2018-06-01

CO2 corrosion behavior of carbon steel with different microstructures (H steel: coarse laminar pearlite; T steel: globular and shot rod shaped pearlite) was analyzed in 3 wt.% NaCl solution at 60 °C with imidazoline-based inhibitor by electrochemical and weight loss methods. Electrochemical measurements showed that, compared to H steel, the inhibitor film adsorbed on T steel had a higher pitting corrosion resistance and the inhibition efficiency for T steel was larger at each concentration of inhibitor. Weight loss results exhibited that both steels suffered general corrosion in absence of inhibitor; however, localized corrosion was observed on the samples with insufficient concentration of inhibitor. H steel suffered more severe localized corrosion than T steel, it was related to that H steel had a higher density of dislocations in the pearlite area and the larger driving force for galvanic corrosion. The localized corrosion on H steel mainly distributed on the laminar pearlite area.

Elasto-inertial turbulence in straight pipes at low Reynolds numbers

NASA Astrophysics Data System (ADS)

Choueiri, George; Hof, Björn

2017-11-01

An early point of contention in the study of polymer drag reduction had been whether polymers delay transition to turbulence or cause it to occur at earlier Reynolds numbers (Re). Recent results have shown that at low polymer concentrations, the subcritical transition to Newtonian type turbulence (NTT) is delayed; however at higher concentrations an elastic instability is encountered which results in a distinct flow state dubbed elasto-inertial turbulence (EIT). Here transition is continuous, fluctuation and friction levels are considerably lower than those for NTT and flow structures are qualitatively different. Several factors can influence the necessary Re for transition to occur for a specific polymer concentration; these include the type of polymer, its molecular weight, the solution viscosity and the proximity of the wall boundaries. By controlling these factors, we have found that chaotic motions can be measured at Re of the order of 1 even in straight smooth pipes as opposed to curved microchannels where curved streamlines cause a purely elastic instability. Furthermore we found that low-Re EIT is closely connected to turbulence that exists on the maximum drag reduction asymptote for polymer solutions with Re several orders of magnitude higher.

An Unusual Salt Effect in an Interfacial Nucleophilic Substitution Reaction.

PubMed

Li, Shuheng; Mrksich, Milan

2018-06-12

This paper reports a kinetic characterization of the interfacial reaction of N-methylpyrrolidine with a self-assembled monolayer presenting an iodoalkyl group. SAMDI (self-assembled monolayers for matrix-assisted laser desorption/ionization) mass spectrometry was used to determine the extent of reaction for monolayers that were treated with a range of concentrations of the nucleophile for a range of times. These data revealed a second-order rate constant for the reaction that was approximately 100-fold greater than that for the analogous solution-phase reaction. However, addition of sodium iodide to the reaction mixture resulted in a 7-fold decrease in the reaction rate. Addition of bromide and chloride salts also gave slower rate constants for the reaction, but only at 100- and 1000-fold higher concentrations than was observed with iodide, respectively. The corresponding solution-phase reactions, by contrast, had rate constants that were unaffected by the concentration of halide salts. This work provides a well-characterized example illustrating the extent to which the kinetics and properties of an interfacial reaction can depart substantially from their better-understood solution-phase counterparts.

Corrosion behavior of ODS steels with several chromium contents in hot nitric acid solutions

NASA Astrophysics Data System (ADS)

Tanno, Takashi; Takeuchi, Masayuki; Ohtsuka, Satoshi; Kaito, Takeji

2017-10-01

Oxide dispersion strengthened (ODS) steel cladding tubes have been developed for fast reactors. Tempered martensitic ODS steels with 9 and 11 wt% of chromium (9Cr-, 11Cr-ODS steel) are the candidate material in research being carried out at JAEA. In this work, fundamental immersion tests and electrochemical tests of 9 to 12Cr-ODS steels were systematically conducted in various nitric acid solutions at 95 °C. The corrosion rate decreased exponentially with effective solute chromium concentration (Creff) and nitric acid concentration. Addition of vanadium (V) and ruthenium (Ru) also decreased the corrosion rate. The combination of low Creff and dilute nitric acid could not avoid the active mass dissolution during active domain at the beginning of immersion, and the corrosion rate was high. Higher Creff decreased the partial anodic current during the active domain and assisted the passivation of the surface of the steel. Concentrated nitric acid and addition of Ru and V increased partial cathodic current and shifted the corrosion potential to noble side. These effects should have prevented the active mass dissolution and decreased the corrosion rate.

In vitro thermal profile suitability assessment of acids and bases for thermochemical ablation: underlying principles.

PubMed

Freeman, Laura A; Anwer, Bilal; Brady, Ryan P; Smith, Benjamin C; Edelman, Theresa L; Misselt, Andrew J; Cressman, Erik N K

2010-03-01

To measure and compare temperature changes in a recently developed gel phantom for thermochemical ablation as a function of reagent strength and concentration with several acids and bases. Aliquots (0.5-1 mL) of hydrochloric acid or acetic acid and sodium hydroxide or aqueous ammonia were injected for 5 seconds into a hydrophobic gel phantom. Stepwise increments in concentration were used to survey the temperature changes caused by these reactions. Injections were performed in triplicate, measured with a thermocouple probe, and plotted as functions of concentration and time. Maximum temperatures were reached almost immediately in all cases, reaching 75 degrees C-110 degrees C at the higher concentrations. The highest temperatures were seen with hydrochloric acid and either base. More concentrated solutions of sodium hydroxide tended to mix incompletely, such that experiments at 9 M and higher were difficult to perform consistently. Higher concentrations for any reagent resulted in higher temperatures. Stronger acid and base combinations resulted in higher temperatures versus weak acid and base combinations at the same concentration. Maximum temperatures obtained are in a range known to cause tissue coagulation, and all combinations tested therefore appeared suitable for further investigation in thermochemical ablation. Because of the loss of the reaction chamber shape at higher concentrations of stronger agents, the phantom does not allow complete characterization under these circumstances. Adequate mixing of reagents to maximize heating potential and avoid systemic exposure to unreacted acid and base must be addressed if the method is to be safely employed in tissues. In addition, understanding factors that control lesion shape in a more realistic tissue model will be critical. Copyright 2010 SIR. Published by Elsevier Inc. All rights reserved.

Different sodium salts cause different solute accumulation in the halophyte Prosopis strombulifera.

PubMed

Llanes, A; Bertazza, G; Palacio, G; Luna, V

2013-01-01

The success of Prosopis strombulifera in growing under high NaCl concentrations involves a carefully controlled balance among different processes, including compartmentation of Cl(-) and Na(+) in leaf vacuoles, exclusion of Na(+) in roots, osmotic adjustment and low transpiration. In contrast, Na(2) SO(4) causes growth inhibition and toxicity. We propose that protection of the cytoplasm can be achieved through production of high endogenous levels of specific compatible solutes. To test our hypothesis, we examined endogenous levels of compatible solutes in roots and leaves of 29-, 40- and 48-day-old P. strombulifera plants grown in media containing various concentrations of NaCl, Na(2) SO(4) or in mixtures of both, with osmotic potentials of -1.0,-1.9 and -2.6 MPa, as correlated with changes in hydric parameters. At 24 h after the last pulse plants grown in high NaCl concentrations had higher relative water content and relatively higher osmotic potential than plants grown in Na(2) SO(4) (at 49 days). These plants also had increased synthesis of proline, pinitol and mannitol in the cytoplasm, accompanied by normal carbon metabolism. When the sulphate anion is present in the medium, the capacities for ion compartmentalisation and osmotic adjustment are reduced, resulting in water imbalance and symptoms of toxicity due to altered carbon metabolism, e.g. synthesis of sorbitol instead of mannitol, reduced sucrose production and protein content. This inhibition was partially mitigated when both anions were present together in the solution, demonstrating a detrimental effect of the sulphate ion on plant growth. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Cyanide and migratory birds at gold mines in Nevada, USA

USGS Publications Warehouse

Henny, C.J.; Hallock, R.J.; Hill, E.F.

1994-01-01

Since the mid-1980s, cyanide in heap leach solutions and mill tailings ponds at gold mines in Nevada has killed a large but incompletely documented number of wildlife ( gt 9,500 individuals, primarily migratory birds). This field investigation documents the availability of cyanide at a variety of 'typical' Nevada gold mines during 1990 and 1991, describes wildlife reactions to cyanide solutions, and discusses procedures for eliminating wildlife loss from cyanide poisoning. Substantial progress has been made to reduce wildlife loss. About half of the mill tailings ponds (some up to 150 ha) in Nevada have been chemically treated to reduce cyanide concentrations (the number needing treatment is uncertain) and many of the smaller heap leach solution ponds and channels are now covered with netting to exclude birds and most mammals. The discovery of a cyanide gradient in mill tailings ponds (concentration usually 2-3 times higher at the inflow point than at reclaim point) provides new insight into wildlife responses (mortality) observed in different portions of the ponds. Finding dead birds on the tops of ore heaps and associated with solution puddling is a new problem, but management procedures for eliminating this source of mortality are available. A safe threshold concentration of cyanide to eliminate wildlife loss could not be determined from the field data and initial laboratory studies. New analytical methods may be required to assess further the wildlife hazard of cyanide in mining solutions.

Study of Separation and Fouling of Reverse Osmosis Membranes during Model Hydrolysate Solution Filtration.

PubMed

Ajao, Olumoye; Rahni, Mohamed; Marinova, Mariya; Chadjaa, Hassan; Savadogo, Oumarou

2017-12-15

Prehydrolysate, a dilute solution consisting mainly of pentoses, hexoses, and lesser quantities of organic acids, furfural and phenolics, is generated in the Kraft dissolving pulp process. An obstacle facing the valorization of the solution in hemicellulose biorefineries, by conversion of the sugars into bioproducts such as furfural, is the low sugar concentration. Membrane filtration is typically proposed in several hemicellulose based biorefineries for concentrating the solution, although they are usually generated using different wood species, pretreatment methods, and operating conditions. However, the chemical composition of the solutions is generally not considered. Also, the combined effect of composition and operating conditions is rarely investigated for biorefinery applications. The purpose of this work was to determine the impact of the prehydrolysate composition and operating parameters on the component separation and permeate flux during membrane filtration. Using model prehydrolysate solutions, two commercial reverse osmosis (RO) membranes were screened, and one was selected for use, based on its higher sugar and acetic acid retention. A Taguchi L18 experimental design array was then applied to determine the dominant parameters and limiting factors. Results showed that the feed pressure and temperature have the highest impact on permeate flux, but the least effect on sugar retention. Further experiments to quantify flux decline, due to fouling and osmotic pressure, showed that furfural has the highest membrane fouling tendency, and can limit the lifetime of the membrane. Regeneration of the membrane by cleaning with a sodium hydroxide solution is also effective for reversing fouling. It has been demonstrated that RO can efficiently and sustainably concentrate wood prehydrolysate.

Study of Separation and Fouling of Reverse Osmosis Membranes during Model Hydrolysate Solution Filtration

PubMed Central

Rahni, Mohamed; Marinova, Mariya; Chadjaa, Hassan; Savadogo, Oumarou

2017-01-01

Prehydrolysate, a dilute solution consisting mainly of pentoses, hexoses, and lesser quantities of organic acids, furfural and phenolics, is generated in the Kraft dissolving pulp process. An obstacle facing the valorization of the solution in hemicellulose biorefineries, by conversion of the sugars into bioproducts such as furfural, is the low sugar concentration. Membrane filtration is typically proposed in several hemicellulose based biorefineries for concentrating the solution, although they are usually generated using different wood species, pretreatment methods, and operating conditions. However, the chemical composition of the solutions is generally not considered. Also, the combined effect of composition and operating conditions is rarely investigated for biorefinery applications. The purpose of this work was to determine the impact of the prehydrolysate composition and operating parameters on the component separation and permeate flux during membrane filtration. Using model prehydrolysate solutions, two commercial reverse osmosis (RO) membranes were screened, and one was selected for use, based on its higher sugar and acetic acid retention. A Taguchi L18 experimental design array was then applied to determine the dominant parameters and limiting factors. Results showed that the feed pressure and temperature have the highest impact on permeate flux, but the least effect on sugar retention. Further experiments to quantify flux decline, due to fouling and osmotic pressure, showed that furfural has the highest membrane fouling tendency, and can limit the lifetime of the membrane. Regeneration of the membrane by cleaning with a sodium hydroxide solution is also effective for reversing fouling. It has been demonstrated that RO can efficiently and sustainably concentrate wood prehydrolysate. PMID:29244761

Electrical potential difference and absorption of water, sodium, and potassium by the terminal ileum of ileostomy patients

PubMed Central

De Moraes-Filho, J. Prado P.; Salas-Coll, C.; Blendis, Laurie; Edmonds, C. J.

1974-01-01

Measurements of electrical potential difference (pd) and of absorption by a dialysis method were carried out in the terminal ileum of patients with an ileostomy. The pd measured with saline in the lumen and at a few centimetres within the stoma averaged 9.2 mV, lumen negatively charged. The pd values were similar whether the ileostomy had been recently or long established. The pd rose considerably when glucose was added to the luminal solution, the maximum effect being attained with a concentration of 40 mmol/1. With a saline bicarbonate solution (Na 145 or 140 m-equiv/1, K 5, or 10 m-equiv/1) in the dialysis tube, considerable absorption of fluid and sodium was demonstrable with little change in sodium concentration. Potassium secretion occurred with the lower, and absorption with the higher, concentration. The final luminal potassium concentration reached was consistent with a passive distribution between blood and lumen. PMID:4448413

Calcium silicate hydrates: Solid and liquid phase composition

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

Lothenbach, Barbara, E-mail: Barbara.lothenbach@empa.ch; Nonat, André

This paper presents a review on the relationship between the composition, the structure and the solution in which calcium silicate hydrate (C–S–H) is equilibrated. The silica chain length in C–S–H increases with the silicon concentration and the calcium content in the interlayer space with the calcium concentrations. Sodium and potassium are taken up in the interlayer space, preferentially at low calcium concentrations and thus by low Ca/Si C–S–H. Aluminium uptake in C–S–H increases strongly at higher aluminium concentrations in the solution. At low Ca/Si, aluminium substitutes silica in the bridging position, at Ca/Si > 1 aluminium is bound in TAH.more » Recently developed thermodynamic models are closely related to the structure of C–S–H and tobermorite, and able to model not only the solubility and the chemical composition of the C–S–H, but also to predict the mean silica chain length and the uptake of aluminium.« less

Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor.

PubMed

Min, C S; Bhatia, S; Kamaruddin, A H

1999-01-01

Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.

Improved Ocular Delivery of Nepafenac by Cyclodextrin Complexation.

PubMed

Shelley, Haley; Grant, Makenzie; Smith, Forrest T; Abarca, Eva M; Jayachandra Babu, R

2018-06-13

Nepafenac is a nonsteroidal anti-inflammatory drug (NSAID), currently only available as 0.1% ophthalmic suspension (Nevanac®). This study utilized hydroxypropyl-β-cyclodextrin (HPBCD) to increase the water solubility and trans-corneal permeation of nepafenac. The nepafenac-HPBCD complexation in the liquid and solid states were confirmed by phase solubility, differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance spectroscopy (NMR) analyses. Nepafenac 0.1% ophthalmic solution was formulated using HPBCD (same pH and osmolality as that of Nevanac®) and pig eye trans-corneal permeation was studied versus Nevanac®. Furthermore, nepafenac content in cornea, sclera, iris, lens, aqueous humor, choroid, ciliary body, retina, and vitreous humor was studied in a continuous isolated pig eye perfusion model in comparison to the suspension and Nevanac®. Permeation studies using porcine corneas revealed that the solution formulation had a permeation rate 18 times higher than Nevanac®. Furthermore, the solution had 11 times higher corneal retention than Nevanac®. Drug distribution studies using porcine eyes revealed that the solution formulation enables detectable levels in various ocular tissues while the drug was undetectable by Nevanac®. The ocular solution formulation had a significantly higher drug concentration in the cornea compared to the suspension or Nevanac®.

Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

PubMed

McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

2017-09-20

The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

Preferential flow systems amended with biogeochemical components: imaging of a two-dimensional study

NASA Astrophysics Data System (ADS)

Pales, Ashley R.; Li, Biting; Clifford, Heather M.; Kupis, Shyla; Edayilam, Nimisha; Montgomery, Dawn; Liang, Wei-zhen; Dogan, Mine; Tharayil, Nishanth; Martinez, Nicole; Moysey, Stephen; Powell, Brian; Darnault, Christophe J. G.

2018-04-01

The vadose zone is a highly interactive heterogeneous system through which water enters the subsurface system by infiltration. This paper details the effects of simulated plant exudate and soil component solutions upon unstable flow patterns in a porous medium (ASTM silica sand; US Silica, Ottawa, IL, USA) through the use of two-dimensional tank light transmission method (LTM). The contact angle (θ) and surface tension (γ) of two simulated plant exudate solutions (i.e., oxalate and citrate) and two soil component solutions (i.e., tannic acid and Suwannee River natural organic matter, SRNOM) were analyzed to determine the liquid-gas and liquid-solid interface characteristics of each. To determine if the unstable flow formations were dependent on the type and concentration of the simulated plant exudates and soil components, the analysis of the effects of the simulated plant exudate and soil component solutions were compared to a control solution (Hoagland nutrient solution with 0.01 M NaCl). Fingering flow patterns, vertical and horizontal water saturation profiles, water saturation at the fingertips, finger dimensions and velocity, and number of fingers were obtained using the light transmission method. Significant differences in the interface properties indicated a decrease between the control and the plant exudate and soil component solutions tested; specifically, the control (θ = 64.5° and γ = 75.75 mN m-1) samples exhibited a higher contact angle and surface tension than the low concentration of citrate (θ = 52.6° and γ = 70.8 mN m-1). Wetting front instability and fingering flow phenomena were reported in all infiltration experiments. The results showed that the plant exudates and soil components influenced the soil infiltration as differences in finger geometries, velocities, and water saturation profiles were detected when compared to the control. Among the tested solutions and concentrations of soil components, the largest finger width (10.19 cm) was generated by the lowest tannic acid solution concentration (0.1 mg L-1), and the lowest finger width (6.00 cm) was induced by the highest SRNOM concentration (10 mg L-1). Similarly, for the plant exudate solutions, the largest finger width (8.36 cm) was generated by the lowest oxalate solution concentration (0.1 mg L-1), and the lowest finger width (6.63 cm) was induced by the lowest citrate concentration (0.1 mg L-1). The control solution produced fingers with average width of 8.30 cm. Additionally, the wettability of the medium for the citrate, oxalate, and SRNOM solutions increased with an increase in concentration. Our research demonstrates that the plant exudates and soil components which are biochemical compounds produced and released in soil are capable of influencing the process of infiltration in soils. The results of this research also indicate that soil wettability, expressed as cosθ1/2, should be included in the scaling of the finger dimension, i.e., finger width, when using the Miller and Miller (1956) scaling theory for the scaling of flow in porous media.

[Effect on the microbicidal efficacy of formaldehyde, glutardialdehyde, peracetic acid, chloramine T (N-chloro-4-toluenesulfonamide), m-cresol, ethanol and benzyldimethyldodecacylammonium bromide by blood (model experiments for chemical disinfection of instruments)].

PubMed

Spicher, G; Peters, J

1998-02-01

In a preceding paper (Zbl. Hyg. 191 [1991] 457-477) we reported on the dependence of the microbicidal efficacy of active agents of the disinfection of instruments on the amount of coagulated blood adhering to the instruments. In the present investigation, we were interested in the dependence of the microbicidal effects on the amount of blood in the solutions of the active agents. Test areas of 2 cm2 were contaminated with 50 and 100 microliters coagulating blood, respectively, containing cells of Staphylococcus aureus as test germ. The solutions of the microbicidal agents were contaminated with heparinized blood up to a concentration of 4% immediately before starting the disinfection and 24 hours before, respectively. After a period of action lasting 1 hour at 20 degrees C, the relative number of test germs capable of multiplying (N/N0) was determined. The concentration of the microbicidal substances reducing the relative number of test germs capable to multiply to 10(-4) served for estimating the dependence of the microbicidal efficacy of the agents on the blood content of the solutions. The experimental results depended on the thickness of the layer of coagulated blood. The dependence of the efficacy of the microbicidal substances on the blood content of the solutions was the higher the thinner the blood layer was. At a thickness of the layer of the coagulated blood of 0.25 mm, a blood content of the solution of 4%, and applying it immediately after adding the blood, the concentration of glutardialdehyde had to be 1.6 times that without blood to reach the same microbicidal efficacy. When applying the solution 24 hours after adding the blood, the concentration of glutardialdehyde had to be 4.2 times that without blood. The quaternary ammonium compound reacted faster with the blood than did glutardialdehyde; the respective factors were 2.6 and 4.5. The concentration factors of chloramine T were 3.3 and 3.8. Under the conditions of the test, peracetic acid exhibited small concentration factors: 1.3 and 1.6. The microbicidal efficacy of ethanol, formaldehyde and m-cresol soap solution was not or only slightly altered by the amount of blood in the solution of the microbicidal agent.

Melittin Aggregation in Aqueous Solutions: Insight from Molecular Dynamics Simulations.

PubMed

Liao, Chenyi; Esai Selvan, Myvizhi; Zhao, Jun; Slimovitch, Jonathan L; Schneebeli, Severin T; Shelley, Mee; Shelley, John C; Li, Jianing

2015-08-20

Melittin is a natural peptide that aggregates in aqueous solutions with paradigmatic monomer-to-tetramer and coil-to-helix transitions. Since little is known about the molecular mechanisms of melittin aggregation in solution, we simulated its self-aggregation process under various conditions. After confirming the stability of a melittin tetramer in solution, we observed—for the first time in atomistic detail—that four separated melittin monomers aggregate into a tetramer. Our simulated dependence of melittin aggregation on peptide concentration, temperature, and ionic strength is in good agreement with prior experiments. We propose that melittin mainly self-aggregates via a mechanism involving the sequential addition of monomers, which is supported by both qualitative and quantitative evidence obtained from unbiased and metadynamics simulations. Moreover, by combining computer simulations and a theory of the electrical double layer, we provide evidence to suggest why melittin aggregation in solution likely stops at the tetramer, rather than forming higher-order oligomers. Overall, our study not only explains prior experimental results at the molecular level but also provides quantitative mechanistic information that may guide the engineering of melittin for higher efficacy and safety.

Fate of cadmium at the soil-solution interface: a thermodynamic study as influenced by varying pH at South 24 Parganas, West Bengal, India.

PubMed

Karak, Tanmoy; Paul, Ranjit Kumar; Das, Sampa; Das, Dilip K; Dutta, Amrit Kumar; Boruah, Romesh K

2015-11-01

A study on the sorption kinetics of Cd from soil solution to soils was conducted to assess the persistence of Cd in soil solution as it is related to the leaching, bioavailability, and potential toxicity of Cd. The kinetics of Cd sorption on two non-contaminated alkaline soils from Canning (22° 18' 48.02″ N and 88° 39' 29.0″ E) and Lakshmikantapur (22° 06' 16.61″ N and 88° 19' 08.66″ E) of South 24 Parganas, West Bengal, India, were studied using conventional batch experiment. The variable soil suspension parameters were pH (4.00, 6.00, 8.18, and 9.00), temperatures (308, 318, and 328 K) and Cd concentrations (5-100 mg L(-1)). The average rate coefficient (kavg) and half-life (t1/2) values indicate that the persistence of Cd in soil solution is influenced by both temperature and soil suspension pH. The concentration of Cd in soil solution decreases with increase of temperature; therefore, Cd sorption on the soil-solution interface is an endothermic one. Higher pH decreases the t 1/2 of Cd in soil solution, indicating that higher pH (alkaline) is not a serious concern in Cd toxicity than lower pH (acidic). Based on the energy of activation (Ea) values, Cd sorption in acidic pH (14.76±0.29 to 64.45±4.50 kJ mol(-1)) is a surface control phenomenon and in alkaline pH (9.33±0.09 to 44.60±2.01 kJ mol(-1)) is a diffusion control phenomenon The enthalpy of activation (ΔH∓) values were found to be between 7.28 and 61.73 kJ mol(-1). Additionally, higher positive energy of activation (ΔG∓) values (46.82±2.01 to 94.47±2.36 kJ mol(-1)) suggested that there is an energy barrier for product formation.

(H, Li)Br and LiOH Solvation Bonding Dynamics: Molecular Nonbond Interactions and Solute Extraordinary Capabilities.

PubMed

Sun, Chang Q; Chen, Jiasheng; Gong, Yinyan; Zhang, Xi; Huang, Yongli

2018-01-25

We resolved the O:H-O bond transition from the mode of ordinary water to its hydration in terms of its phonon stiffness (vibration frequency shift Δω), order of fluctuation (line width), and number fraction (phonon abundance), f x (C) = N hyd /N total . The f x (C) follows f H (C) = 0, f Li (C) ∝ f OH (C) ∝ C, and f Br (C) ∝ 1 - exp(-C/C 0 ) toward saturation with C being the solute concentration. The invariant df x (C)/dC suggests that the solute forms a constantly sized hydration droplet without responding to interference of other ions because its hydrating H 2 O dipoles fully screen its electric field. However, the number inadequacy of the highly ordered hydration H 2 O dipoles partially screens the large Br - . The Br - then interacts repulsively with other Br - anions, which weakens its electric field and the f Br (C) approaches saturation at higher solute concentration. The consistency in the concentration trend of the f LiBr (C), the Jones-Dole viscosity η(C), and the surface stress of LiBr solution clarifies their common origin of ionic polarization. The resultant energy of the solvent H-O exothermic elongation by O: ⇔ :O repulsion and the solute H-O endothermic contraction by bond-order deficiency heats up the LiOH solution. An estimation of at least 0.15 eV (160% of the O:H cohesive energy of 0.1 eV) suggests that the H-O elongation is the main source heating up the solution, while the molecular motion, structure fluctuation, or even evaporation dissipates energy caped at 0.1 eV.

Investigation of influence of conductivity on the polyaniline fiber mats, produced via electrospinning

NASA Astrophysics Data System (ADS)

Varnaitė-Žuravliova, Sandra; Savest, Natalja; Abraitienė, Aušra; Baltušnikaitė-Guzaitienė, Julija; Krumme, Andres

2018-05-01

Intrinsically conductive polymers are one very attractive material, because of their good electrical, electrochemical and optical properties, and a wide range of applications. The spinnability of Polyaniline (PANI) solutions is generally insufficient for it to be electrospun directly into fibers, but addition of another polymer to the organic solutions or usage of dopant and solvent may improve it. The aim of the research was: to produce nanofibers of the smallest diameter as possible by using conventional electrospinning setup; to investigate the influence of viscosity and electrical conductivity to the spinnability of PANI solutions; to control the electrical conductivity of prepared solutions and electrospun nanofibers by changing concentrations of chemicals used. The results of investigations made with prepared solutions shave showed, that the viscosity increases and the electrical conductivity is tending to decrease with increase of Polyethylenoxide (PEO) concentration in the spinning solution. In order to achieve greater conductivity, the Dimethylformamide (DMF) was added as a dopant. Though the conductivity of solutions was reached high enough, but the loss in viscosity resulted in depriation of greater spinnability of PANI nanofibers. Also it was noticed, that despite the fact that the electrical conductivity of all solutions was different, the electrical conductivity of fiber mats can be divided in two groups: fiber mats without DMF and fiber mats with DMF. The morphological analysis of produced fiber mats have showed, that higher PEO concentration resulted in thicker PANI nanofibers—the diameter varied from 333 nm till 4434 nm. The usage of DMF gave an opportunity to receive almost twice thinner conductive PANI nanofibers with narrower distribution in diameter. Slower flow rate of the electrospinning process resulted in thinner nanofibers as well.

The effect of polymer composition on the gelation behavior of PLGA-g-PEG biodegradable thermoreversible gels.

PubMed

Tarasevich, B J; Gutowska, A; Li, X S; Jeong, B-M

2009-04-01

Graft copolymers consisting of a poly(D,L-lactic acid-co-glycolic acid) backbone grafted with polyethylene glycol side chains were synthesized and formed thermoreversible gels in aqueous solutions that exhibited solution behavior at low temperature and sol-to-gel transitions at higher temperature. The composition of the polymer and relative amounts of polylactic acid, glycolic acid, and ethylene glycol were varied by controlling the precursor concentrations and reaction temperature. The gelation temperature could be systematically tailored from 15 to 34 degrees C by increasing the concentration of polyethylene glycol in the graft copolymer. The gelation temperature also depended on the polymer molecular weight and concentration. This work has importance for the development of water soluble gels with tailored compositions and gelation temperatures for use in tissue engineering and as injectable depots for drug delivery. Copyright 2008 Wiley Periodicals, Inc.

Radiation synthesis and characterization of hyaluronan capped gold nanoparticles.

PubMed

Hien, Nguyen Quoc; Van Phu, Dang; Duy, Nguyen Ngoc; Quoc, Le Anh

2012-06-20

Gold nanoparticles (AuNPs) with diameter from 4 to 10nm, capping by hyaluronan (HA) were synthesized using a γ-irradiation method. The maximum absorption wavelengths at 517-525 nm of colloidal AuNPs/HA solutions were measured by UV-vis spectroscopy. The size and size distribution of AuNPs were determined from TEM images. The influence of various factors on the size of AuNPs particularly the concentration of Au3+ and HA, and dose rate were also investigated. Results indicated that higher dose rate and HA concentration favor smaller sizes of AuNPs whereas the size increases with Au3+ concentration. The colloidal AuNPs/HA solution was fairly stable more than 6 months under storage at ambient condition. The AuNPs stabilized by biocompatible HA with the size less than 10nm as prepared can potentially be applied in biomedicines and cosmetics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Temperature transition of human hemoglobin at body temperature: effects of calcium.

PubMed Central

Kelemen, C; Chien, S; Artmann, G M

2001-01-01

We studied the effects of calcium ion concentration on the temperature dependence of rheological behavior of human red blood cells (RBCs) and concentrated hemoglobin solutions. Our previous study (G. M. Artmann, C. Kelemen, D. Porst, G. Büldt, and S. Chien, 1998, Biophys. J., 75:3179-3183) showed a critical temperature (Tc) of 36.4 +/- 0.3 degrees C at which the RBCs underwent a transition from non-passage to passage through 1.3 microm micropipettes in response to an aspiration pressure of -2.3 kPa. An increase in intracellular Ca2+ concentration by using the ionophore A23187 reduced the passability of intact RBCs through small micropipettes above T(c); the micropipette diameter needed for >90% passage increased to 1.7 microm. Viscometry of concentrated hemoglobin solutions (45 and 50 g/dl) showed a sudden viscosity transition at 36 +/- 1 degrees C (Tc(eta)) at all calcium concentrations investigated. Below Tc(eta), the viscosity value of the concentrated hemoglobin solution at 1.8 mM Ca(2+) was higher than that at other concentrations (0.2 microM, 9 mM, and 18 mM). Above Tc(eta), the viscosity was almost Ca2+ independent. At 1.8 mM Ca2+ and 36 +/- 1 degrees C, the activation energy calculated from the viscometry data showed a strong dependence on the hemoglobin concentration. We propose that the transition of rheological behavior is attributable to a high-to-low viscosity transition mediated by a partial release of the hemoglobin-bound water. PMID:11371439

Tissue dissolution by sodium hypochlorite: effect of concentration, temperature, agitation, and surfactant.

PubMed

Stojicic, Sonja; Zivkovic, Slavoljub; Qian, Wei; Zhang, Hui; Haapasalo, Markus

2010-09-01

Sodium hypochlorite is the most commonly used endodontic irrigant because of its antimicrobial and tissue-dissolving activity. The aim of this study was to evaluate and compare the effects of concentration, temperature, and agitation on the tissue-dissolving ability of sodium hypochlorite. In addition, a hypochlorite product with added surface active agent was compared with conventional hypochlorite solutions. Three sodium hypochlorite solutions from two different manufacturers in concentrations of 1%, 2%, 4%, and 5.8% were tested at room temperature, 37 degrees C, and 45 degrees C with and without agitation by ultrasonic and sonic energy and pipetting. Distilled and sterilized tap water was used as controls. Pieces of bovine muscle tissue (68 +/- 3 mg) were placed in 10 mL of each solution for five minutes. In selected samples, agitation was performed for one, two, or four 15-second periods per each minute. The tissue specimens were weighed before and after treatment, and the percentage of weight loss was calculated. The contact angle on dentin of the three solutions at concentrations of 1% and 5.8% was measured. Weight loss (dissolution) of the tissue increased almost linearly with the concentration of sodium hypochlorite. Higher temperatures and agitation considerably enhanced the efficacy of sodium hypochlorite. The effect of agitation on tissue dissolution was greater than that of temperature; continuous agitation resulted in the fastest tissue dissolution. Hypochlorite with added surface active agent had the lowest contact angle on dentin and was most effective in tissue dissolution in all experimental situations. Optimizing the concentration, temperature, flow, and surface tension can improve the tissue-dissolving effectiveness of hypochlorite even 50-fold. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Imaging transport phenomena during lysozyme protein crystal growth by the hanging drop technique

NASA Astrophysics Data System (ADS)

Sethia Gupta, Anamika; Gupta, Rajive; Panigrahi, P. K.; Muralidhar, K.

2013-06-01

The present study reports the transport process that occurs during the growth of lysozyme protein crystals by the hanging drop technique. A rainbow schlieren technique has been employed for imaging changes in salt concentration. A one dimensional color filter is used to record the deflection of the light beam. An optical microscope and an X-ray crystallography unit are used to characterize the size, tetragonal shape and Bravais lattice constants of the grown crystals. A parametric study on the effect of drop composition, drop size, reservoir height and number of drops on the crystal size and quality is reported. Changes in refractive index are not large enough to create a meaningful schlieren image in the air gap between the drop and the reservoir. However, condensation of fresh water over the reservoir solution creates large changes in the concentration of NaCl, giving rise to clear color patterns in the schlieren images. These have been analyzed to obtain salt concentration profiles near the free surface of the reservoir solution as a function of time. The diffusion of fresh water into the reservoir solution at the early stages of crystal growth followed by the mass flux of salt from the bulk solution towards the free surface has been recorded. The overall crystal growth process can be classified into two regimes, as demarcated by the changes in slope of salt concentration within the reservoir. The salt concentration in the reservoir equilibrates at long times when the crystallization process is complete. Thus, transport processes in the reservoir emerge as the route to monitor protein crystal growth in the hanging drop configuration. Results show that crystal growth rate is faster for a higher lysozyme concentration, smaller drops, and larger reservoir heights.

Monte Carlo and mean-field studies of phase evolution in concentrated surfactant solutions

NASA Astrophysics Data System (ADS)

Bohbot, Yardena; Ben-Shaul, Avinoam; Granek, Rony; Gelbart, William M.

1995-11-01

A two-dimensional lattice model, originally introduced by Granek et al. [J. Chem. Phys. 101, 4331 (1994)], is used to demonstrate the intricate coupling between the intramicellar interactions that determine the optimal aggregation geometry of surfactant molecules in dilute solution, and the intermicellar interactions that govern the phase behavior at higher concentrations. Three very different scenarios of self-assembly and phase evolution are analyzed in detail, based on Monte Carlo studies and theoretical interpretations involving mean-field, Landau-Ginzburg, Bethe-Peierls, and virial expansion schemes. The basic particles in the model are ``unit micelles'' which, due to spontaneous self-assembly or because of excluded area interactions, can fuse to form larger aggregates. These aggregates are envisaged as flat micelles composed of a bilayerlike body surrounded by a curved semitoroidal rim. The system's Hamiltonian involves one- through four-body potentials between the unit micelles, which account for their tendency to form aggregates of different shapes, e.g., elongated vs disklike micelles. Equivalently, the configurational energy of the system is a sum of micellar self-energies involving the packing free energies of the constituent molecules in the bilayer body and in rim segments of different local curvature. The rim energy is a sum of a line tension term and a 1D curvature energy which depends on the rim spontaneous curvature and bending rigidity. Different combinations of these molecular parameters imply different optimal packing geometries and hence different self-assembly and phase behaviors. The emphasis in this paper is on systems of ``curvature loving'' amphiphiles which, in our model, are characterized by negative line tension. The three systems studied are: (i) A dilute solution of stable disklike micelles which, upon increasing the concentration, undergoes a first-order phase transition to a continuous bilayer with isolated hole defects. An intermediate modulated ``checkerboard'' phase appears under certain conditions at low temperatures. (ii) A system of unit micelles which in dilute solution tend to associate into linear micelles. These micelles are rodlike at low temperatures, becoming increasingly more flexible as the temperature increases. Upon increasing the concentration the micelles grow and undergo (in 2D) a continuous transition into nematic and ``stripe'' phases of long rods. At still higher concentrations the micellar stripes fuse into continuous sheets with line defects. (iii) A system in which, already in dilute solution, the micelles favor the formation of branched aggregates, analogous to the branched cylindrical micelles recently observed in certain surfactant solutions. As the concentration increases the micelles associate into networks (``gels'') composed of a mesh of linear micelles linked by ``T-like'' intermicellar junctions. The network may span the entire system or phase separate and coexist with a dilute micellar phase, depending on the details of the molecular packing parameters.

Solution self-assembly and adsorption at the air-water interface of the monorhamnose and dirhamnose rhamnolipids and their mixtures.

PubMed

Chen, M L; Penfold, J; Thomas, R K; Smyth, T J P; Perfumo, A; Marchant, R; Banat, I M; Stevenson, P; Parry, A; Tucker, I; Grillo, I

2010-12-07

The self-assembly in solution and adsorption at the air-water interface, measured by small-angle neutron scattering, SANS, and neutron reflectivity, NR, of the monorhamnose and dirhamnose rhamnolipids (R1, R2) and their mixtures, are discussed. The production of the deuterium-labeled rhamnolipids (required for the NR studies) from a Pseudomonas aeruginosa culture and their separation into the pure R1 and R2 components is described. At the air-water interface, R1 and R2 exhibit Langmuir-like adsorption isotherms, with saturated area/molecule values of about 60 and 75 Å(2), respectively. In R1/R2 mixtures, there is a strong partitioning of R1 to the surface and R2 competes less favorably because of the steric or packing constraints of the larger R2 dirhamnose headgroup. In dilute solution (<20 mM), R1 and R2 form small globular micelles, L(1), with aggregation numbers of about 50 and 30, respectively. At higher solution concentrations, R1 has a predominantly planar structure, L(α) (unilamellar, ULV, or bilamellar, BLV, vesicles) whereas R2 remains globular, with an aggregation number that increases with increasing surfactant concentration. For R1/R2 mixtures, solutions rich in R2 are predominantly micellar whereas solutions rich in R1 have a more planar structure. At an intermediate composition (60 to 80 mol % R1), there are mixed L(α)/L(1) and L(1)/L(α) regions. However, the higher preferred curvature associated with R2 tends to dominate the mixed R1/R2 microstructure and its associated phase behavior.

Alpha radiolysis of nitric acid and sodium nitrate with 4He2+ beam of 13.5 MeV energy

NASA Astrophysics Data System (ADS)

Garaix, G.; Venault, L.; Costagliola, A.; Maurin, J.; Guigue, Mireille; Omnee, R.; Blain, G.; Vandenborre, J.; Fattahi, M.; Vigier, N.; Moisy, P.

2015-01-01

A study of aqueous nitric acid solution alpha radiolysis was performed through experiments carried out at a cyclotron facility, where a helion beam with an energy of 13.5 MeV could be delivered into the solution. The effects of nitrate and hydronium ions on the formation yields of hydrogen peroxide and nitrous acid, G(H2O2) and G(HNO2), were studied. The results showed that G(H2O2) decreases linearly with increasing nitrate ion concentration. On the other hand, G(HNO2) increases with the nitrate ion concentration until it reaches a plateau for nitric acid concentrations higher than 2 mol L-1. It was also found that an increase of hydronium ion concentration has a favorable effect on G(H2O2) and G(HNO2). Furthermore, it appears that these effects are additive and that the variations of G(H2O2) and G(HNO2) can be described by two parametric expressions, as a function of the nitrate and hydronium ion concentrations.

Decomposition Behavior of Curcumin during Solar Irradiation when Contact with Inorganic Particles

NASA Astrophysics Data System (ADS)

Nandiyanto, A. B. D.; Wiryani, A. S.; Rusli, A.; Purnamasari, A.; Abdullah, A. G.; Riza, L. S.

2017-03-01

Curcumin is one of materials which have been widely used in medicine, Asian cuisine, and traditional cosmetic. Therefore, understanding the stability of curcumin has been widely studied. The purpose of this study was to investigate the stability of curcumin solution against solar irradiation when making contact with inorganic material. As a model for the inorganic material, titanium dioxide (TiO2) was used. In the experimental method, the curcumin solution was irradiated using a solar irradiation. To confirm the stability of curcumin when contact with inorganic material, we added TiO2 micro particles with different concentrations. The results showed that the concentration of curcumin decreased during solar irradiation. The less concentration of curcumin affected the more decomposition rate obtained. The decomposition rate was increased greatly when TiO2 was added, in which the more TiO2 concentration added allowed the faster decomposition rate. Based on the result, we conclude that the curcumin is relatively stable as long as using higher concentration of curcumin and is no inorganic material existed. Then, the decomposition can be minimized by avoiding contact with inorganic material.

Influence of compositional complexity on interdiffusion in Ni-containing concentrated solid-solution alloys

DOE PAGES

Jin, Ke; Zhang, Chuan; Zhang, Fan; ...

2018-03-07

To investigate the compositional effects on thermal-diffusion kinetics in concentrated solid-solution alloys, interdiffusion in seven diffusion couples with alloys from binary to quinary is systematically studied. The alloys with higher compositional complexity exhibit in general lower diffusion coefficients against homologous temperature, however, an exception is found that diffusion in NiCoFeCrPd is faster than in NiCoFeCr and NiCoCr. While the derived diffusion parameters suggest that diffusion in medium and high entropy alloys is overall more retarded than in pure metals and binary alloys, they strongly depend on specific constituents. The comparative features are captured by computational thermodynamics approaches using a self-consistentmore » database.« less

Nuclear staining with alum hematoxylin.

PubMed

Llewellyn, B D

2009-08-01

The hematoxylin and eosin stain is the most common method used in anatomic pathology, yet it is a method about which technologists ask numerous questions. Hematoxylin is a natural dye obtained from a tree originally found in Central America, and is easily converted into the dye hematein. This dye forms coordination compounds with mordant metals, such as aluminum, and the resulting lake attaches to cell nuclei. Regressive formulations contain a higher concentration of dye than progressive formulations and may also contain a lower concentration of mordant. The presence of an acid increases the life of the solution and in progressive solutions may also affect selectivity of staining. An appendix lists more than 60 hemalum formulations and the ratio of dye to mordant for each.

Stiffness and evolution of interfacial micropancakes revealed by AFM quantitative nanomechanical imaging.

PubMed

Zhao, Binyu; Wang, Xingya; Song, Yang; Hu, Jun; Lü, Junhong; Zhou, Xingfei; Tai, Renzhong; Zhang, Xuehua; Zhang, Lijuan

2015-05-28

Micropancakes are quasi-two-dimensional micron-sized domains on crystalline substrates (e.g. highly oriented pyrolytic graphite (HOPG)) immersed in water. They are only a few nanometers thick, and are suspected to come from the accumulation of dissolved air at the solid-water interface. However, the exact chemical nature and basic physical properties of micropancakes have been under debate ever since their first observation, primarily due to the lack of a suitable characterization technique. In this study, the stiffness of micropancakes at the interface between HOPG and ethanol-water solutions was investigated by using PeakForce Quantitative NanoMechanics (PF-QNM) mode Atomic Force Microscopy (AFM). Our measurements showed that micropancakes were stiffer than nanobubbles, and for bilayer micropancakes, the bottom layer in contact with the substrate was stiffer than the top one. Interestingly, the micropancakes became smaller and softer with an increase in the ethanol concentration in the solution, and were undetectable by AFM above a critical concentration of ethanol. But they re-appeared after the ethanol concentration in the solution was reduced. Clearly the evolution and stiffness of the micropancakes were dependent on the chemical composition in the solution, which could be attributed to the correlation of the mechanical properties of the micropancakes with the surface tension of the liquid phase. Based on the "go-and-come" behaviors of micropancakes with the ethanol concentration, we found that the micropancakes could actually tolerate the ethanol concentration much higher than 5%, a value reported in the literature. The results from this work may be helpful in alluding the chemical nature of micropancakes.

The effect of topography and rock type on soil cation contents and stream solute and phosphorus concentrations of streams in the southwestern Brazilian Amazon basin.

NASA Astrophysics Data System (ADS)

Biggs, T. W.; Dunne, T.; Holmes, K.; Martinelli, L. A.

2001-12-01

Topography plays an important role in determining soil properties, stream solute concentrations and landscape denudation rates. Stallard (1985) suggested that catchment denudation rates should depend on soil thickness. Areas with low slopes are limited by the rate of transport of sediment, and typically contain thick soils that prevent interaction of stream waters with underlying bedrock [Stallard 1985]. Steep areas typically have thin soils, but a lower hydrologic residence time that may prevent soil water from coming into thermodynamic equilibrium with the soil-rock complex. In a survey of streams in the Brazilian Amazon basin, Biggs et al. (2001) found that stream solute concentrations correlate with soil cation contents in the humid tropics, but the mechanism underlying the correlation has not been determined. We combine chemical analyses of water samples from ~40 different streams with soil surveys, geology maps, and a 100m resolution DEM to examine the relationship between topography, rock type, soil cation contents, and stream solute concentrations in the Brazilian Amazon state of Rondônia. The basins are all more than 60% forested at the time of stream sampling and lie on granite-gneiss rocks, tertiary sediments, or sandstone. The catchment-averaged slope correlates positively with both soil cation contents and stream concentrations of P, Na, Ca, Mg, K, Si, ANC, and pH. Though we have no data about the relationship between soil depth and average slope, we assume an inverse correlation, so the data demonstrates that thick soils yield lower solute concentrations. Stream concentrations of Ca, Mg, ANC and pH reach a maximum at intermediate average slopes (3 degrees), suggesting that denudation rates may increase with slope up to a maximum, when the catchment becomes limited by the weathering rate of the basement rock. Catchments on mica-schists or mafic rocks have low average slopes and higher concentrations of Ca, Mg, Si, ANC, and pH than catchments on granite-gneiss, tertiary sediments or sandstone.

Adsorption interactions of humic acids with biocides

NASA Astrophysics Data System (ADS)

Mal'Tseva, E. V.; Ivanov, A. A.; Yudina, N. V.

2009-11-01

The chemical composition of humic acids from brown coal (Aldrich) was determined by element analysis, 13C NMR spectroscopy, and potentiometric titration. The adsorption ability of humic acids with different biocides (cyproconasol, propiconasol, tebuconasol, irgarol 1051, and DCOIT) was studied. The adsorption ability of a mixture of biocides in aqueous solutions was higher than that of the individual components. The limiting concentration of humic acids at which adsorption of biocides was maximum was determined. Adsorption constants were calculated by the Freundlich equation for each biocide in aqueous solution.

Sodium triflate decreases interaggregate repulsion and induces phase separation in cationic micelles.

PubMed

Lima, Filipe S; Cuccovia, Iolanda M; Buchner, Richard; Antunes, Filipe E; Lindman, Björn; Miguel, Maria G; Horinek, Dominik; Chaimovich, Hernan

2015-03-10

Dodecyltrimethylammonium triflate (DTATf) micelles possess lower degree of counterion dissociation (α), lower hydration, and higher packing of monomers than other micelles of similar structure. Addition of sodium triflate ([NaTf] > 0.05 M) to DTATf solutions promotes phase separation. This phenomenon is commonly observed in oppositely charged surfactant mixtures, but it is rare for ionic surfactants and relatively simple counterions. While the properties of DTATf have already been reported, the driving forces for the observed phase separation with added salt remain unclear. Thus, we propose an interpretation for the observed phase separation in cationic surfactant solutions. Addition of up to 0.03 M NaTf to micellar DTATf solutions led to a limited increase of the aggregation number, to interface dehydration, and to a progressive decrease in α. The viscosity of DTATf solutions of higher concentration ([DTATf] ≥ 0.06 M) reached a maximum with increasing [NaTf], though the aggregation number slightly increased, and no shape change occurred. We hypothesize that this maximum results from a decrease in interaggregate repulsion, as a consequence of increased ion binding. This reduction in micellar repulsion without simultaneous infinite micellar growth is, probably, the major driving force for phase separation at higher [NaTf].

Effect of sodium tripolyphosphate concentration and simulated gastrointestinal fluids on release profile of paracetamol from chitosan microsphere

NASA Astrophysics Data System (ADS)

Mulia, Kamarza; Andrie; Krisanti, Elsa A.

2018-03-01

The problem to overcome in oral drug administration is the significant pH changes present in the human digestive system. In this study, ionotropic gelation method employing 2-8% (w/v) tripolyphosphate solutions were used to crosslink chitosan microspheres for a controlled release of paracetamol as a model drug. The release profiles of paracetamol from chitosan microspheres were determined using simulated gastrointestinal fluids having pH values of 1.2, 6.8, and 7.4. The results showed that the paracetamol loading and the encapsulation efficiency values increased with increasing concentration of tripolyphosphate solutions used in the preparation step. Paracetamol released at pH 1.2 and 6.8 buffer solutions was significantly higher than that at pH 7.4; also, more paracetamol was released in the presence of α-amylase and β-glucosidase enzymes. The release profiles showed zero-order release behaviour up to 8 hours where the highest drug release was 39% of the paracetamol loaded in the chitosan microspheres, indicating a strong crosslinking between chitosan and TPP anions. The relatively low accumulated drug release could be compensated by employing suitable enzymes, lower TPP solution concentration, and addition of other biodegradable polymer to reduce the TPP crosslink.

Measuring calcium, potassium, and nitrate in plant nutrient solutions using ion-selective electrodes in hydroponic greenhouse of some vegetables.

PubMed

Vardar, Gökay; Altıkatoğlu, Melda; Ortaç, Deniz; Cemek, Mustafa; Işıldak, İbrahim

2015-01-01

Generally, the life cycle of plants depends on the uptake of essential nutrients in a balanced manner and on toxic elements being under a certain concentration. Lack of control of nutrient levels in nutrient solution can result in reduced plant growth and undesired conditions such as blossom-end rot. In this study, sensitivity and selectivity tests for various polyvinylchloride (PVC)-based ion-selective membranes were conducted to identify those suitable for measuring typical concentration ranges of macronutrients, that is, NO(3-), K(+), and Ca(2+), in hydroponic solutions. The sensitivity and selectivity of PVC-membrane-based ion-selective sensors prepared with tetradodecylammoniumnitrate for NO(3-), valinomycin for K(+), and Ca ionophore IV for Ca(2+) were found to be satisfactory for measuring NO(3-), K(+), and Ca(2+) ions in nutrient solutions over typical ranges of hydroponic concentrations. Potassium, calcium, and nitrate levels that were utilized by cucumber and tomato seedlings in the greenhouse were different. The findings show that tomato plants consumed less amounts of nitrate than cucumber plants over the first 2 months of their growth. We also found that the potassium intake was higher than other nutritional elements tested for all plants. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

Forces between Two Glass Surfaces with Adsorbed Hexadecyltrimethylammonium Salicylate.

PubMed

Imae, T; Kato, M; Rutland, M

2000-02-22

Forces have been measured for hexadecyltrimethylammonium salicylate (C(16)TASal) layers on glass beads. During the inward process, hydrophobic attraction occurred at lower adsorption of C(16)TASal and electrostatic repulsion interactions happened at higher adsorption. While the jump-in phenomenon was observed for solutions of concentrations below the critical micelle concentration (cmc = 0.15 mM), the step-in phenomenon was characteristic for solutions at the cmc and above the cmc, suggesting the push-out of adsorbed C(16)TASal layers and/or inserted micelles. The remarkable pull-off phenomenon on the outward process occurred for all solutions, indicating a strong interaction between C(16)TASal molecules. For aqueous 0.15 mM C(16)TASal solutions of various NaSal concentrations, on the inward process, the electrostatic repulsive interaction decreased with adding NaSal. This is due to the electrostatic shielding by salt excess. The height of the force wall on the inward process reached a maximum at 0.01 M NaSal, but the interlocking between molecules on two surfaces during the outward process was minimized at 0.1 M NaSal. These tendencies, which are different from that of the electrostatic repulsion interaction, imply the strong cohesion between adsorbed C(16)TASal layers.

Recent advances in f-element separations based on a new method for the production of pentavalent americium in acidic solution

DOE PAGES

Mincher, Bruce J.; Schmitt, Nicholas C.; Schuetz, Brian K.; ...

2015-03-11

The peroxydisulfate anion has long been used for the preparation of hexavalent americium (Am VI) from the normally stable Am III valence state in mildly acidic solutions. However, there has been no satisfactory means to directly prepare the pentavalent state (Am V) in that medium. Some early literature reports indicated that the peroxydisulfate oxidation was incomplete, and silver ion catalysis in conjunction with peroxydisulfate became accepted as the means to ensure quantitative generation of Am VI. Incomplete oxidation would be expected to leave residual Am III, or to produce Am V in treated solutions. However, until recently, the use ofmore » peroxydisulfate as an Am V reagent has not been reported. Here, parameters influencing the oxidation were investigated, including peroxydisulfate and acid concentration, temperature, duration of oxidative treatment, and the presence of higher concentrations of other redox active metals such as plutonium. Using optimized conditions determined here, quantitative Am V was prepared in an acidic solution and the UV/Vis extinction coefficients of the Am V 513 nm peak were measured over a range of nitric acid concentrations. Furthermore, the utility of Am V for separations from the lanthanides and curium by solvent extraction, organic column chromatography and inorganic ion exchangers was also investigated.« less

The effect of pH and chloride concentration on the stability and antimicrobial activity of chlorine-based sanitizers.

PubMed

Waters, Brian W; Hung, Yen-Con

2014-04-01

Chlorinated water and electrolyzed oxidizing (EO) water solutions were made to compare the free chlorine stability and microbicidal efficacy of chlorine-containing solutions with different properties. Reduction of Escherichia coli O157:H7 was greatest in fresh samples (approximately 9.0 log CFU/mL reduction). Chlorine loss in "aged" samples (samples left in open bottles) was greatest (approximately 40 mg/L free chlorine loss in 24 h) in low pH (approximately 2.5) and high chloride (Cl(-) ) concentrations (greater than 150 mg/L). Reduction of E. coli O157:H7 was also negatively impacted (<1.0 log CFU/mL reduction) in aged samples with a low pH and high Cl(-) . Higher pH values (approximately 6.0) did not appear to have a significant effect on free chlorine loss or numbers of surviving microbial cells when fresh and aged samples were compared. This study found chloride levels in the chlorinated and EO water solutions had a reduced effect on both free chlorine stability and its microbicidal efficacy in the low pH solutions. Greater concentrations of chloride in pH 2.5 samples resulted in decreased free chlorine stability and lower microbicidal efficacy. © 2014 Institute of Food Technologists®

THE PREPARATION AND PROPERTIES OF HIGHLY PURIFIED ASCORBIC ACID OXIDASE

PubMed Central

Powers, Wendell H.; Lewis, Stanley; Dawson, Charles R.

1944-01-01

1. A method is described for the preparation of a highly purified ascorbic acid oxidase containing 0.24 per cent copper. 2. Using comparable activity measurements, this oxidase is about one and a half times as active on a dry weight basis as the hitherto most highly purified preparation described by Lovett-Janison and Nelson. The latter contained 0.15 per cent copper. 3. The oxidase activity is proportional to the copper content and the proportionality factor is the same as that reported by Lovett-Janison and Nelson. 4. When dialyzed free of salt, the blue concentrated oxidase solutions precipitate a dark green-blue protein which carries the activity. This may be prevented by keeping the concentrated solutions about 0.1 M in Na2HPO4. 5. When highly diluted for activity measurements the oxidase rapidly loses activity (irreversibly) previous to the measurement, unless the dilution is made with a dilute inert protein (gelatin) solution. Therefore activity values obtained using such gelatin-stabilized dilute solutions of the oxidase run considerably higher than values obtained by the Lovett-Janison and Nelson technique. 6. The effect of pH and substrate concentration on the activity of the purified oxidase in the presence and absence of inert protein was studied. PMID:19873382

Production and Rheological Properties of Welan Gum Produced by Sphingomonas sp. ATCC 31555 with Different Nitrogen Sources.

PubMed

Xu, Xiaopeng; Nie, Zuoming; Zheng, Zhiyong; Zhu, Li; Zhan, Xiaobei

2017-01-01

This study aimed to investigate the effect of nitrogen sources on the production and rheological properties of welan gum produced by Sphingomonas sp. ATCC 31555. Six different nitrogen sources were used for ATCC 31555 fermentation, and 2 of these were further analyzed due to their more positive influence on welan gum production and bacterial biomass. Bacterial biomass, welan gum yield, welan viscosity, molecular weight, monosaccharide composition, acyl content, and welan structure were analyzed. Welan gum production and the biomass concentration of ATCC 31555 were higher in media containing NaNO3 and beef extract. Welan viscosity decreased at higher temperatures of 30-90°C, and it increased with a higher welan concentration. In the media containing NaNO3 (3 g·L-1), welan viscosity was higher at 30-70°C and a welan solution concentration of 6-10 g·L-1. With a reduced NaNO3 concentration, the molecular weight of welan gum and the molar ratio of mannose decreased, but the molar ratio of glucuronic acid increased. With different nitrogen sources, the acetyl content of welan gum differed but its structure was similar. NaNO3 and beef extract facilitated welan production. A reduced NaNO3 concentration promoted welan viscosity. © 2017 S. Karger AG, Basel.

Production of acetone butanol ethanol (ABE) by a hyper-producing mutant strain of Clostridium beijerinckii BA101 and recovery by pervaporation

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

Qureshi, N.; Blaschek, H.P.

1999-07-01

A silicone membrane was used to study butanol separation from model butanol solutions and fermentation broth. Depending upon the butanol feed concentration in the model solution and pervaporation conditions, butanol selectivities of 20.88--68.32 and flux values of 158.7--215.4 g m{sup {minus}2} h{sup {minus}1} were achieved. Higher flux values were obtained at higher butanol concentrations using air as sweep gas. In an integrated process of butanol fermentation--recovery, solvent productivities were improved to 200% of the control batch fermentation productivities. In a batch reactor the hyper-butanol-producing mutant strain C. beijerinckii BA101 utilized 57.3 g/L glucose and produced 24.2 g/L total solvents, whilemore » in the integrated process it produced 51.5 g/L (culture volume) total solvents. Concentrated glucose medium was also fermented. The C. beijerinckii BA101 mutant strain was not negatively affected by the pervaporative conditions. In the integrated experiment, acids were not produced. With the active fermentation broth, butanol selectivity was reduced by a factor of 2--3. However, the membrane flux was not affected by the active fermentation broth. The butanol permeate concentration ranged from 26.4 to 95.4 g/L, depending upon butanol concentration in the fermentation broth. Since the permeate of most membranes contains acetone, butanol, and ethanol, it is suggested that distillation be used for further purification.« less

Impact of model perfume molecules on the self-assembly of anionic surfactant sodium dodecyl 6-benzene sulfonate.

PubMed

Bradbury, Robert; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Jones, Craig; Grillo, Isabelle

2013-03-12

The impact of two model perfumes with differing degrees of hydrophobicity/hydrophilicity, linalool (LL) and phenylethanol (PE), on the solution structure of anionic surfactant sodium dodecyl 6-benzene sulfonate, LAS-6, has been studied by small angle neutron scattering, SANS. For both types of perfume molecules, complex phase behavior is observed. The phase behavior depends upon the concentration, surfactant/perfume composition, and type of perfume. The more hydrophilic perfume PE promotes the formation of more highly curved structures. At relatively low surfactant concentrations, small globular micelles, L1, are formed. These become perfume droplets, L(sm), stabilized by the surfactant at much higher perfume solution compositions. At higher surfactant concentrations, the tendency of LAS-6 to form more planar structures is evident. The more hydrophobic linalool promotes the formation of more planar structures. Combined with the greater tendency of LAS-6 to form planar structures, this results in the planar structures dominating the phase behavior for the LAS-6/linalool mixtures. For the LAS-6/linalool mixture, the self-assembly is in the form of micelles only at the lowest surfactant and perfume concentrations. Over most of the concentration-composition space explored, the structures are predominantly lamellar, L(α), or vesicle, L(v), or in the form of a lamellar/micellar coexistence. At low and intermediate amounts of LL, a significantly different structure is observed, and the aggregates are in the form of small, relatively monodisperse vesicles (i.e., nanovesicles), L(sv).

Response of aluminum solubility to elevated nitrification in soil of a red spruce stand in eastern Maine

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.

1997-01-01

Elevated concentrations of soluble Al can impair tree growth and be toxic to aquatic biota, but effects of acidic deposition on Al solubility in forest soils are only partially understood because of complex interactions with H+ and organic matter. We therefore evaluated Al solubility in two red spruce stands in eastern Maine, one of which received dry (NH4)2SO4 at a rate of 1800 equiv ha-1 yr-1 during 19891995. Samples of soil (Spodosol Oa and Bh horizons) and soil solution were collected on five dates from 1992 to 1995. The treatment elevated nitrification, causing an increase in acid input that led to inorganic Al concentrations of greater than 60 ??mol L-1 in both the Oa and Bh horizons. Solubility of Al was also lower in the Bh horizon of the treated stand than in the reference stand, a response related to higher DOC concentrations in the treated stand. Concentrations of CuCl2 and pyrophosphate-extractable Al were higher in the Oa horizon of the treated watershed than the reference stand, a result of accelerated weathering of mineral particles caused by lower solution pH in the treated stand (3.47) than in the reference stand (3.69). Dissolved Al concentrations in these soils are the result of complex mechanisms through which mineral matter, organic matter, and pH interact to control Al solubility; mechanisms that are not incorporated in current Al solubility models.

Electrochemical EDTA recycling after soil washing of Pb, Zn and Cd contaminated soil.

PubMed

Pociecha, Maja; Kastelec, Damijana; Lestan, Domen

2011-08-30

Recycling of chelant decreases the cost of EDTA-based soil washing. Current methods, however, are not effective when the spent soil washing solution contains more than one contaminating metal. In this study, we applied electrochemical treatment of the washing solution obtained after EDTA extraction of Pb, Zn and Cd contaminated soil. A sacrificial Al anode and stainless steel cathode in a conventional electrolytic cell at pH 10 efficiently removed Pb from the solution. The method efficiency, specific electricity and Al consumption were significantly higher for solutions with a higher initial metal concentration. Partial replacement of NaCl with KNO(3) as an electrolyte (aggressive Cl(-) are required to prevent passivisation of the Al anode) prevented EDTA degradation during the electrolysis. The addition of FeCl(3) to the acidified washing solution prior to electrolysis improved Zn removal. Using the novel method 98, 73 and 66% of Pb, Zn and Cd, respectively, were removed, while 88% of EDTA was preserved in the treated washing solution. The recycled EDTA retained 86, 84 and 85% of Pb, Zn and Cd extraction potential from contaminated soil, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Reversible Condensation of DNA using a Redox-Active Surfactant

PubMed Central

Hays, Melissa E.; Jewell, Christopher M.; Lynn, David M.; Abbott, Nicholas L.

2008-01-01

We report characterization of aqueous solutions of dilute Lambda phage DNA containing the redox-active surfactant (11-ferrocenylundecyl)trimethylammonium bromide (FTMA) as a function of the oxidation state of the FTMA. FTMA undergoes a reversible one-electron oxidation from a reduced state that forms micelles in aqueous solution to an oxidized state (containing the ferrocenium cation) that does not selfassociate in solution. This investigation sought to test the hypothesis that FTMA can be used to achieve reversible control over the conformation of DNA-surfactant complexes in solution. Whereas DNA adopts extended coil conformations in aqueous solutions, our measurements revealed that addition of reduced FTMA (2–5μM) to aqueous solutions of DNA (5 μM in nucleotide units) resulted in coexistence of extended coils and compact globules in solution. At higher concentrations of reduced FTMA (up to 30μM), the DNA was present as compact globules only. In contrast, oxidized FTMA had no measurable effect on the conformation of DNA, allowing DNA to maintain an extended coil state up to a concentration of 75μM oxidized FTMA. We further demonstrate that it is possible to chemically or electrochemically transform the oxidation state of FTMA in preformed complexes of FTMA and DNA, thus achieving in situ control over the conformations of the DNA in solution. These results provide guidance for the design of surfactant systems that permit active control of DNA-surfactant interactions. PMID:17428073

Process for separating and recovering an anionic dye from an aqueous solution

DOEpatents

Rogers, R.; Horwitz, E.P.; Bond, A.H.

1998-01-13

A solid/liquid phase process for the separation and recovery of an anionic dye from an aqueous solution is disclosed. The solid phase comprises separation particles having surface-bonded poly(ethylene glycol) groups, whereas the aqueous solution from which the anionic dye molecules are separated contains a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt. After contact between the aqueous solution and separation particles, the anionic dye is bound to the particles. The bound anionic dye molecules are freed from the separation particles by contacting the anionic dye-bound particles with an aqueous solution that does not contain a poly(ethylene glycol) liquid/liquid biphase-forming amount of a dissolved lyotropic salt to form an aqueous anionic dye solution whose anionic dye concentration is preferably higher than that of the initial dye-containing solution. 7 figs.

Pontine and Thalamic Influences on Fluid Rewards: III. Anticipatory Contrast for Sucrose and Corn Oil

PubMed Central

Liang, Nu-Chu; Norgren, Ralph; Grigson, Patricia S

2011-01-01

An anticipatory contrast effect (ACE) occurs when, across daily trials, an animal comes to respond less than normally to a first stimulus when it is followed shortly by a second, more preferred solution. Classically, ACE is studied using a low (L) concentration of saccharin or sucrose, followed by access to a higher (H) concentration of sucrose. Subjects in the control condition have two bouts of access to the weaker solution presented on the same schedule. The ACE is measured by the difference in intake of the first bout low solution between subjects in the low-low (L-L) vs. the low-high (L-H) conditions. Here we used this paradigm with sham feeding rats and determined that nutritional feedback was unnecessary for the development of ACE with two concentrations of sucrose or with two concentrations of corn oil. Next we showed that ibotenic acid lesions centered in the orosensory thalamus spared ACEs for both sucrose and corn oil. In contrast, lesions of the pontine parabrachial nuclei (PBN), the second central relay for taste in the rat, disrupted ACEs for both sucrose and corn oil. Although the sensory modalities needed for the oral detection of fats remain controversial, it appears that the PBN is involved in processing the comparison of disparate concentrations of sucrose and oil reward. PMID:21703289

Tetragonal Lysozyme Nucleation and Crystal Growth: The Role of the Solution Phase

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Forsythe, Elizabeth; Sumida, John; Maxwell, Daniel; Gorti, Sridhar

2002-01-01

Lysozyme, and most particularly the tetragonal form of the protein, has become the default standard protein for use in macromolecule crystal nucleation and growth studies. There is a substantial body of experimental evidence, from this and other laboratories, that strongly suggests this proteins crystal nucleation and growth is by addition of associated species that are preformed by standard reversible concentration-driven self association processes in the bulk solution. The evidence includes high resolution AFM studies of the surface packing and of growth unit size at incorporation, fluorescence resonance energy transfer measurements of intermolecular distances in dilute solution, dialysis kinetics, and modeling of the growth rate data. We have developed a selfassociation model for the proteins crystal nucleation and growth. The model accounts for the obtained crystal symmetry, explains the observed surface structures, and shows the importance of the symmetry obtained by self-association in solution to the process as a whole. Further, it indicates that nucleation and crystal growth are not distinct mechanistically, but identical, with the primary difference being the probability that the particle will continue to grow or dissolve. This model also offers a possible mechanism for fluid flow effects on the growth process and how microgravity may affect it. While a single lysozyme molecule is relatively small (M.W. = 14,400), a structured octamer in the 4(sub 3) helix configuration (the proposed average sized growth unit) would have a M.W. = 115,000 and dimensions of 5.6 x 5.6 x 7.6 nm. Direct AFM measurements of growth unit incorporation indicate that units as wide as 11.2 nm and as long as 11.4 nm commonly attach to the crystal. These measurements were made at approximately saturation conditions, and they reflect the sizes of species that both added or desorbed from the crystal surface. The larger and less isotropic the associated species the more likely that it will be oriented to some degree in a flowing boundary layer, even at the low flow velocities measured about macromolecule crystals. Flow-driven effects resulting in misorientation upon addition to and incorporation into the crystal need only be a small fraction of a percentage to significantly affect the resulting crystal. One Earth, concentration gradient driven flow will maintain a high interfacial concentration, i.e., a high level (essentially that of the bulk solution) of solute association at the interface and higher growth rate. Higher growth rates mean an increased probability that misaligned growth units are trapped by subsequent growth layers before they can be desorbed and try again, or that the desorbing species will be smaller than the adsorbing species. In microgravity the extended diffusive boundary layer will lower the interfacial concentration. This results in a net dissociation of aggregated species that diffuse in from the bulk solution, i.e., smaller associated species, which are more likely able to make multiple attempts to correctly bind, yielding higher quality crystals.

Determination of metal concentrations in certified plastic reference materials after small-size autoclave and microwave-assisted digestion followed with inductively coupled plasma optical emission spectrometry

NASA Astrophysics Data System (ADS)

Lehtimäki, Esa; Väisänen, Ari

2017-01-01

The digestion methods for the determination of As, Cd, Cr, Pb, Sb, Sn and Zn concentrations in plastic samples using microwave-assisted digestion (MW-AD) and small-size autoclave digestion was developed. The certified polyethylene, polypropylene, polyvinyl chloride and acrylonitrile butadiene styrene certified reference materials were used in order to find digestion method working properly for several sample matrices. Efficiency of the digestion methods was evaluated by analyzing the residual carbon in digests by TOC analyzer. MW-AD using a mixture of 7 mL of HNO3 and 3 mL of H2O2 as a digestion solution resulted in excellent recoveries for As, Cd, Pb, Sb and Zn, and were in the range of 92-107% for all the analytes except Pb in polyethylene material. Autoclave digestion using 5 mL of concentrated HNO3 as a digestion solution resulted in similar recoveries with the exception of a higher As recovery (98%). Tin recovery resulted in low level after both MW-AD and autoclave digestion. Autoclave digestion was further developed resulting in a partially open two-step digestion process especially for the determination of Sn and Cr. The method resulted in higher recoveries of Sn and Cr (87 and 76%) but with the lower concentration of easily volatile As, Cd and Sb.

Specification of matrix cleanup goals in fractured porous media.

PubMed

Rodríguez, David J; Kueper, Bernard H

2013-01-01

Semianalytical transient solutions have been developed to evaluate what level of fractured porous media (e.g., bedrock or clay) matrix cleanup must be achieved in order to achieve compliance of fracture pore water concentrations within a specified time at specified locations of interest. The developed mathematical solutions account for forward and backward diffusion in a fractured porous medium where the initial condition comprises a spatially uniform, nonzero matrix concentration throughout the domain. Illustrative simulations incorporating the properties of mudstone fractured bedrock demonstrate that the time required to reach a desired fracture pore water concentration is a function of the distance between the point of compliance and the upgradient face of the domain where clean groundwater is inflowing. Shorter distances correspond to reduced times required to reach compliance, implying that shorter treatment zones will respond more favorably to remediation than longer treatment zones in which back-diffusion dominates the fracture pore water response. For a specified matrix cleanup goal, compliance of fracture pore water concentrations will be reached sooner for decreased fracture spacing, increased fracture aperture, higher matrix fraction organic carbon, lower matrix porosity, shorter aqueous phase decay half-life, and a higher hydraulic gradient. The parameters dominating the response of the system can be measured using standard field and laboratory techniques. © 2012, The Author(s). Ground Water © 2012, National Ground Water Association.

Contribution of gustation to the palatability of linoleic acid.

PubMed

Saitou, Katsuyoshi; Yoneda, Takeshi; Mizushige, Takafumi; Asano, Hiroki; Okamura, Maya; Matsumura, Shigenobu; Eguchi, Ai; Manabe, Yasuko; Tsuzuki, Satoshi; Inoue, Kazuo; Fushiki, Tohru

2009-01-08

We investigated the palatability of a low concentration of linoleic acid (LA) in short-term two-bottle choice tests and licking tests. To examine the contribution of gustation, mice were rendered anosmic with olfactory nerve transection surgery and test solutions were prepared using mineral oil (saturated long-chain hydrocarbon) to minimize textural effects. In the two-bottle choice tests between various pairs of different concentrations of corn oil and LA, both anosmic and the sham-operated mice constantly preferred a higher concentration of corn oil and LA. In the licking tests, the initial licking rate for 1% LA was higher than that for mineral oil in anosmic mice. In accordance with the results of the two-bottle choice test, the initial licking rate for corn oil and LA increased in a concentration-dependent manner in both anosmic and sham-operated mice in the licking test, and reached its peak at 100% corn oil and 1% LA. A preference comparison between 1% LA and 100% corn oil showed that anosmic mice preferred 1% LA over 100% corn oil. These results suggest that mice could recognize dietary fat and fatty acid solutions in the oral cavity without any olfactory or textural cues and the fatty acid recognition on their tongues might provide a pivotal cue to how dietary fat is recognized in the oral cavity.

Emulsifying properties and oil/water (O/W) interface adsorption behavior of heated soy proteins: effects of heating concentration, homogenizer rotating speed, and salt addition level.

PubMed

Cui, Zhumei; Chen, Yeming; Kong, Xiangzhen; Zhang, Caimeng; Hua, Yufei

2014-02-19

The adsorption of heat-denatured soy proteins at the oil/water (O/W) interface during emulsification was studied. Protein samples were prepared by heating protein solutions at concentrations of 1-5% (w/v) and were then diluted to 0.3% (w/v). The results showed that soy proteins that had been heated at higher concentrations generated smaller droplet size of emulsion. Increase in homogenizer rotating speed resulted in higher protein adsorption percentages and lower surface loads at the O/W interface. Surface loads for both unheated and heated soy proteins were linearly correlated with the unadsorbed proteins' equilibrium concentration at various rotating speeds. With the rise in NaCl addition level, protein adsorption percentage and surface loads of emulsions increased, whereas lower droplet sizes were obtained at the ionic strength of 0.1 M. The aggregates and non-aggregates displayed different adsorption behaviors when rotating speed or NaCl concentration was varied.

Testing near-infrared spectrophotometry using a liquid neonatal head phantom

NASA Astrophysics Data System (ADS)

Wolf, Martin; Baenziger, Oskar; Keel, Matthias; Dietz, Vera; von Siebenthal, Kurt; Bucher, Hans U.

1998-12-01

We constructed a liquid phantom, which mimics the neonatal head for testing near infrared spectrophotometry instruments. It consists of a spherical, 3.5 mm thick layer of silicone rubber simulating skin and bone and acts as container for a liquid solution with IntralipidTM, 60 micrometers ol/l haemoglobin and yeast. The IntralipidTM concentration was varied to test the influence of scattering on haemoglobin concentrations and tissue oxygenation determined by the Critikon 2020. The solution was oxygenated using pure oxygen and then deoxygenated by the yeast. For the instruments algorithm, we found with increasing scattering (0.5%, 1%, 1.5% and 2% IntralipidTM concentration) an increasing offset added to the oxy- (56.7, 90.8, 112.5, 145.2 micrometers ol/l respectively) and deoxyhaemoglobin (25.4, 44.3, 58.5, 65.9 micrometers ol/l) concentration causing a decreasing range (41.3, 31.3, 25.0, 22.2%) of the tissue oxygen saturation reading. However, concentration changes were quantified correctly independently of the scattering level. For an other algorithm based on the analytical solution the offsets were smaller: oxyhaemoglobin 12.2, 34.0, 53.2, 88.8 micrometers ol/l and deoxyhaemoglobin 1.6, 11.2, 22.2, 28.1 micrometers ol/l. The range of the tissue oxygen saturation reading was higher: 71.3, 55.5, 45.7, 39.4%. However, concentration changes were not quantified correctly and depended on scattering. This study demonstrates the need to develop algorithms, which take into consideration the anatomical structures.

Effect of pretreatment and membrane orientation on fluxes for concentration of whey with high foulants by using NH3/CO2 in forward osmosis.

PubMed

Seker, M; Buyuksari, E; Topcu, S; Babaoglu, D S; Celebi, D; Keskinler, B; Aydiner, C

2017-11-01

Usage of forward osmosis membrane in FO mode, in which active and support layers of the membrane were in contact with the feed and the draw solutions respectively, provided higher initial water flux (12L/m 2 h) than the usage of membrane in PRO mode (6L/m 2 h) having opposite orientation but fluxes approached to each other after 4h during concentration of whey with NH 3 /CO 2 as draw salt. High organic and inorganic foulants of whey was considered as reason for observed result in addition to lower solute resistivity. Initial water flux (8,5L/m 2 h) was lower when pre-treatment was applied before forward osmosis process but final flux (4L/m 2 h) was equal flux of non pre-treatment. Reduction of solute resistivity or absence of hydraulic pressure can be reasons for lower initial flux. Detection of organic carbon but absence of lactose in draw solution showed passage of molecules being different than lactose into draw solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Pervaporation Study of Ammonia Solutions Using Molecular Sieve Silica Membranes

PubMed Central

Yang, Xing; Fraser, Thomas; Myat, Darli; Smart, Simon; Zhang, Jianhua; Diniz da Costa, João C.; Liubinas, Audra; Duke, Mikel

2014-01-01

An innovative concept is proposed to recover ammonia from industrial wastewater using a molecular sieve silica membrane in pervaporation (PV), benchmarked against vacuum membrane distillation (VMD). Cobalt and iron doped molecular sieve silica-based ceramic membranes were evaluated based on the ammonia concentration factor downstream and long-term performance. A modified low-temperature membrane evaluation system was utilized, featuring the ability to capture and measure ammonia in the permeate. It was found that the silica membrane with confirmed molecular sieving features had higher water selectivity over ammonia. This was due to a size selectivity mechanism that favoured water, but blocked ammonia. However, a cobalt doped silica membrane previously treated with high temperature water solutions demonstrated extraordinary preference towards ammonia by achieving up to a 50,000 mg/L ammonia concentration (a reusable concentration level) measured in the permeate when fed with 800 mg/L of ammonia solution. This exceeded the concentration factor expected by the benchmark VMD process by four-fold, suspected to be due to the competitive adsorption of ammonia over water into the silica structure with pores now large enough to accommodate ammonia. However, this membrane showed a gradual decline in selectivity, suspected to be due to the degradation of the silica material/pore structure after several hours of operation. PMID:24957120

Contribution of transformation products towards the total herbicide toxicity to tropical marine organisms.

PubMed

Mercurio, Philip; Eaglesham, Geoff; Parks, Stephen; Kenway, Matt; Beltran, Victor; Flores, Florita; Mueller, Jochen F; Negri, Andrew P

2018-03-19

The toxicity of herbicide degradation (transformation) products is rarely taken into account, even though these are commonly detected in the marine environment, sometimes at concentrations higher than the parent compounds. Here we assessed the potential contribution of toxicity by transformation products of five photosystem II herbicides to coral symbionts (Symbiodinium sp.), the green algae Dunaliella sp., and prawn (Penaeus monodon) larvae. Concentration-dependent inhibition of photosynthetic efficiency (∆F/F m ') was observed for all herbicides in both microalgal species. The toxicity of solutions of aged diuron solutions containing transformation products to Symbiodinium sp. and Dunaliella sp. was greater than could be explained by the concentrations of diuron measured, indicating transformation products contributed to the inhibition of ∆F/F m '. However, the toxicity of aged atrazine, simazine, hexazinone, and ametryn solutions could be explained by the concentration of parent herbicide, indicating no contribution by transformation products. Prawn larval metamorphosis was not sensitive to the herbicides, but preliminary results indicated some toxicity of the transformation products of atrazine and diuron. Risk assessments should take into account the contribution of herbicide transformation products; however, further studies are clearly needed to test the toxicity of a far wider range of transformation products to a representative diversity of relevant taxa.

Effect of white tea and xylitol on structure and properties of demineralized enamel and jawbone

NASA Astrophysics Data System (ADS)

Auerkari, EI; Kiranahayu, R.; Emerita, D.; Sumariningsih, P.; Sarita, D.; Adiwirya, MS; Suhartono, AW

2018-05-01

White tea and xylitol have been suggested as potential agents to combat dental caries and osteoporosis through enhanced remineralization. This investigation aimed to determine the effects of exposure to white tea with and without xylitol on the structure, composition and hardness of demineralized human dental enamel. For control, samples of untreated and demineralized enamel and samples of untreated rat jawbone were subjected to similar measurements. For demineralization, the enamel samples were immersed for two days at 50°C in an acetate solution (pH 4.0). All samples were then soaked for two weeks at 37°C in a solution containing three different concentrations of white tea, xylitol or both, and an optional addition of the remineralization ingredients including Ca, P and F. For enamel samples without preceding demineralization and without added remineralization ingredients, the results showed highest mean hardness after immersion in a solution containing both white tea and xylitol, practically independently of their applied concentration level. However, for demineralized enamel samples with added remineralization ingredients, the resulting mean hardness was also dependent on concentration of white tea and xylitol. With sufficient concentration, hardness was again higher for combined white tea and xylitol than for either of these used alone.

Steady-state solidification of aqueous ammonium chloride

NASA Astrophysics Data System (ADS)

Peppin, S. S. L.; Huppert, Herbert E.; Worster, M. Grae

We report on a series of experiments in which a Hele-Shaw cell containing aqueous solutions of NH4Cl was translated at prescribed rates through a steady temperature gradient. The salt formed the primary solid phase of a mushy layer as the solution solidified, with the salt-depleted residual fluid driving buoyancy-driven convection and the development of chimneys in the mushy layer. Depending on the operating conditions, several morphological transitions occurred. A regime diagram is presented quantifying these transitions as a function of freezing rate and the initial concentration of the solution. In general, for a given concentration, increasing the freezing rate caused the steady-state system to change from a convecting mushy layer with chimneys to a non-convecting mushy layer below a relatively quiescent liquid, and then to a much thinner mushy layer separated from the liquid by a region of active secondary nucleation. At higher initial concentrations the second of these states did not occur. At lower concentrations, but still above the eutectic, the mushy layer disappeared. A simple mathematical model of the system is developed which compares well with the experimental measurements of the intermediate, non-convecting state and serves as a benchmark against which to understand some of the effects of convection. Movies are available with the online version of the paper.

Relating soil solution Zn concentration to diffusive gradients in thin films measurements in contaminated soils.

PubMed

Degryse, Fien; Smolders, Erik; Oliver, Ian; Zhang, Hao

2003-09-01

The technique of diffusive gradients in thin films (DGT) has been suggested to sample an available fraction of metals in soil. The objectives of this study were to compare DGT measurements with commonly measured fractions of Zn in soil, viz, the soil solution concentration and the total Zn concentration. The DGT technique was used to measure fluxes and interfacial concentrations of Zn in three series of field-contaminated soils collected in transects toward galvanized electricity pylons and in 15 soils amended with ZnCl2 at six rates. The ratio of DGT-measured concentration to pore water concentration of Zn, R, varied between 0.02 and 1.52 (mean 0.29). This ratio decreased with decreasing distribution coefficient, Kd, of Zn in the soil, which is in agreement with the predictions of the DGT-induced fluxes in soils (DIFS) model. The R values predicted with the DIFS model were generally larger than the observed values in the ZnCl2-amended soils at the higher Zn rates. A modification of the DIFS model indicated that saturation of the resin gel was approached in these soils, despite the short deployment times used (2 h). The saturation of the resin with Zn did not occur in the control soils (no Zn salt added) or the field-contaminated soils. Pore water concentration of Zn in these soils was predicted from the DGT-measured concentration and the total Zn content. Predicted values and observations were generally in good agreement. The pore water concentration was more than 5 times underpredicted for the most acid soil (pH = 3) and for six other soils, for which the underprediction was attributed to the presence of colloidal Zn in the soil solution.

Caustic stress corrosion cracking of alloys 600 and 690 with NaOH concentrations

NASA Astrophysics Data System (ADS)

Park, In-Gyu; Lee, Chang-Soon; Hwang, Seong-Sik; Kim, Hong-Pyo; Kim, Joung-Soo

2005-10-01

In order to evaluate the stress corrosion cracking resistance for commercial alloys (C600MA, C600TT, C690TT) and Korean-made alloys (K600MA, K690TT), C-ring tests were performed in a caustic environment of 4, 10, 20, 30, and 50% NaOH solution at 315°C, for 480 h with an applied potential of 125 mV vs. OCP. Different stress corrosion cracking phenomena were observed according to the NaOH concentration. The rate of caustic IGSCC attack did not appear to increase monotonically with caustic concentrations, but peaked at a concentration between 4 and 50% caustic, or approximately 30% NaOH. Intergranular stress corrosion cracking was found for C600MA in 10, 20, and 30% NaOH solutions, while no cracking was observed in the 4 and 50% NaOH solutions. In 30% NaOH solution, transgrnular stress corrosion cracking was detected in C690TT, which may be related with the large amount of plastic strain (150% yield) and the applied potential (125 mV vs. OCP). The overall data clearly indicate that C600MA has the worst SCC resistance while K690TT offers the best resistance. There is also fairly good correlation between the caustic SCC susceptibility and some metallurgical parameters, particularly the grain size and the yield strength at room temperature. Specifically, materials having larger grain size and lower yield strength exhibited higher caustic SCC resistance.

Glycemic and insulinemic responses to different preexercise snacks in participants with impaired fasting glucose.

PubMed

Byrne, Heidi K; Kim, Yeonsoo; Hertzler, Steven R; Watt, Celia A; Mattern, Craig O

2011-02-01

To compare serum glucose and insulin responses to 3 preexercise snacks before, during, and after exercise in individuals with impaired fasting glucose (IFG) and healthy (H) men. In addition, in an IFG population, the authors sought to determine whether a natural fruit snack (i.e., raisins) yields more desirable glucose and insulin concentrations than an energy bar or a glucose solution. The IFG (n = 11, age = 54.5 ± 1.3 yr, fasting blood glucose [BG] = 6.3 ± 0.1 mmol/L) and H groups (n = 9, age = 48.0 ± 3.1 yr, fasting BG = 4.9 ± 0.1 mmol/L) cycled at 50% of VO2peak for 45 min on 4 occasions after consuming water or 50 g of carbohydrate from raisins (R), an energy bar (EB), or a glucose beverage (GLU). Metabolic markers were measured before, during, and after exercise. In all nutritional conditions, glucose concentrations of the IFG group were consistently higher than in the H group. Differences between IFG and H groups in insulin concentrations were sporadic and isolated. In the IFG group, preexercise glucose concentration was lower in the R condition than in GLU. Ten and 20 min into exercise, glucose concentrations in the R and EB conditions were lower than in GLU. Insulin concentrations were lower in the R condition than in EB and GLU immediately before exercise and at Minute 10 but at 20 min R remained lower than only GLU. Glucose concentrations were higher in the IFG group regardless of preexercise snack. Compared with the glucose solution, raisins lowered both the postprandial glycemic and insulinemic responses, whereas the energy bar reduced glycemia but not insulinemia.

Effect of enterocin AS-48 in combination with biocides on planktonic and sessile Listeria monocytogenes.

PubMed

Gómez, Natacha Caballero; Abriouel, Hikmate; Grande, M A José; Pulido, Rubén Pérez; Gálvez, Antonio

2012-05-01

Enterocin AS-48 was tested on a cocktail of Listeria monocytogenes strains in planktonic and sessile states, singly or in combination with biocides benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, didecyldimethylammonium bromide, triclosan, poly-(hexamethylen guanidinium) hydrochloride, chlorhexidine, hexachlorophene, and the commercial sanitizers P3 oxonia and P3 topax 66. Combinations of sub-inhibitory bacteriocin concentrations and biocide concentrations 4 to 10-fold lower than their minimum inhibitory concentrations (MIC) completely inhibited growth of the planktonic listeriae. Inactivation of Listeria in biofilms formed on polystyrene microtiter plates required concentrations of enterocin AS-48 greater than 50 μg/ml, and biocide concentrations ten to 100-fold higher. In combination with enterocin AS-48 (25 or 50 μg/ml), microbial inactivation increased remarkably for all biocides except P3 oxonia and P3 topax 66 solutions. Polystyrene microtiter plates conditioned with enterocin solutions (0.5-25 μg/ml) decreased the adherence and biofilm formation of the L. monocytogenes cell cocktail, avoiding biofilm formation for at least 24 h at a bacteriocin concentration of 25 μg/ml. Copyright © 2011 Elsevier Ltd. All rights reserved.

Crustal solute fluxes and transient carbon dioxide drawdown in the Scottbreen Basin, Svalbard in 2002

NASA Astrophysics Data System (ADS)

Krawczyk, Wiesława Ewa; Bartoszewski, Stefan A.

2008-12-01

SummarySolute fluxes and transient carbon dioxide drawdown in a small glacierized basin investigated on Svalbard in 2002 are presented. It was a sample year within a period of significant climate warming in the Arctic. Discharge was recorded in the Scottbreen Basin (10.1 km 2), Bellsund Fjord, between July 8 and September 10, 2002. Specific runoff for this period was 0.784 m, 22% more than the mean for 1986-2001. The runoff for all of 2002 (i.e. the hydrologic year) was estimated by comparison with Bayelva, the only glacial river with longer records on Svalbard. The specific runoff for 2002 was ˜1.228 m, yielding crustal solute fluxes of 69.4 t km -2 yr -1 (25.8 m 3 km -2 yr -1). This rate is the highest chemical denudation rate reported from glacierized basins on Svalbard, and it may be underestimated because higher solute fluxes at the beginning of the melt season were not taken into account. Crustal fluxes in the fall may also have been higher because it is probable that crustal ion concentrations were increasing after recording stopped in September. The cation denudation rate was 1213 ∑ meq + m -2 yr -1 and the mean annual crustal ion concentration derived from it amounted to 981 μeq L -1. Transient CO 2 drawdown in 2002 was 5242 kg C km -2 yr -1. Most of the carbon dioxide was removed in the summer ablation waters, estimated CO 2 drawdown in the fall being only 13% of the total. Comparison with crustal solute fluxes (CSF) computed from specific conductivity in the 1980s and 1990s suggests that earlier fluxes may have been overestimated by around 19%. Comparing earlier data with the 2002 rates may confirm the influence of climate warming on increasing chemical denudation rates. It was also found that a globally derived equation relating specific conductivity to concentrations of dissolved limestone in water gave estimates of the crustal solute fluxes that were only 1.1% less than those obtained via comprehensive chemical analyses of waters and ion partitioning procedures.

Acid-Base and Plasma Biochemical Changes Using Crystalloid Fluids in Stranded Juvenile Loggerhead Sea Turtles (Caretta caretta).

PubMed

Camacho, María; Quintana, María Del Pino; Calabuig, Pascual; Luzardo, Octavio P; Boada, Luis D; Zumbado, Manuel; Orós, Jorge

2015-01-01

The aim of this study was to compare the efficacy and effects on acid-base and electrolyte status of several crystalloid fluids in 57 stranded juvenile loggerhead turtles. Within a rehabilitation program four different crystalloid fluids were administered (0.9% Na Cl solution; 5% dextrose + 0.9% Na Cl solutions 1:1; 0.9% Na Cl + lactated Ringer's solutions 1:1; lactated Ringer's solution). Crystalloid fluids were intracoelomically administered during three days (20 ml/kg/day). Animals were sampled at three different moments: Upon admission for evaluating the type of acid-base or biochemical disorder, post-fluid therapy treatment for controlling the evolution of the disorder, and post-recovery period for obtaining the baseline values for rehabilitated loggerhead turtles. Each sample was analyzed with a portable electronic blood analyzer for pH, pO2, pCO2, lactate, sodium, potassium, chloride, glucose, and BUN concentration. Admission and post-fluid therapy treatment values were compared with those obtained for each turtle immediately before release. The highest percentage of acid-base recovery and electrolyte balance was observed in turtles treated with mixed saline-lactated Ringer's solution (63.6%), followed by turtles treated with physiological saline solution (55%), lactated Ringer's solution (33.3%), and dextrose-saline solutions (10%). Most turtles treated with lactated Ringer's solution had lower lactate concentrations compared with their initial values; however, 66.6% of turtles treated with lactated Ringer's solution had metabolic alkalosis after therapy. Significant higher concentrations of glucose were detected after saline-dextrose administration compared with all the remaining fluids. This is the first study evaluating the effects of several crystalloid fluids on the acid-base status and plasma biochemical values in stranded loggerhead sea turtles. Reference convalescent venous blood gas, acid-base, and plasma biochemical values, useful for veterinary surgeons involved in sea turtle conservation, are also provided.

Purifying fluoride-contaminated water by a novel forward osmosis design with enhanced flux under reduced concentration polarization.

PubMed

Pal, Madhubonti; Chakrabortty, Sankha; Pal, Parimal; Linnanen, Lassi

2015-08-01

For purifying fluoride-contaminated water, a new forward osmosis scheme in horizontal flat-sheet cross flow module was designed and investigated. Effects of pressure, cross flow rate, draw solution and alignment of membrane module on separation and flux were studied. Concentration polarization and reverse salt diffusion got significantly reduced in the new hydrodynamic regime. This resulted in less membrane fouling, better solute separation and higher pure water flux than in a conventional module. The entire scheme was completed in two stages-an upstream forward osmosis for separating pure water from contaminated water and a downstream nanofiltration operation for continuous recovery and recycle of draw solute. Synchronization of these two stages of operation resulted in a continuous, steady-state process. From a set of commercial membranes, two polyamide composite membranes were screened out for the upstream and downstream filtrations. A 0.3-M NaCl solution was found to be the best one for forward osmosis draw solution. Potable water with less than 1% residual fluoride could be produced at a high flux of 60-62 L m(-2) h(-1) whereas more than 99% draw solute could be recovered and recycled in the downstream nanofiltration stage from where flux was 62-65 L m(-2) h(-1).

Effect of wood ash application on soil solution chemistry of tropical acid soils: incubation study.

PubMed

Nkana, J C Voundi; Demeyer, A; Verloo, M G

2002-12-01

The objective of this study was to determine the effect of wood ash application on soil solution composition of three tropical acid soils. Calcium carbonate was used as a reference amendment. Amended soils and control were incubated for 60 days. To assess soluble nutrients, saturation extracts were analysed at 15 days intervals. Wood ash application affects the soil solution chemistry in two ways, as a liming agent and as a supplier of nutrients. As a liming agent, wood ash application induced increases in soil solution pH, Ca, Mg, inorganic C, SO4 and DOC. As a supplier of elements, the increase in the soil solution pH was partly due to ligand exchange between wood ash SO4 and OH- ions. Large increases in concentrations of inorganic C, SO4, Ca and Mg with wood ash relative to lime and especially increases in K reflected the supply of these elements by wood ash. Wood ash application could represent increased availability of nutrients for the plant. However, large concentrations of basic cations, SO4 and NO3 obtained with higher application rates could be a concern because of potential solute transport to surface waters and groundwater. Wood ash must be applied at reasonable rates to avoid any risk for the environment.

Do centrally pre-prepared solutions achieve more reliable drug concentrations than solutions prepared on the ward?

PubMed

Dehmel, Carola; Braune, Stephan A; Kreymann, Georg; Baehr, Michael; Langebrake, Claudia; Hilgarth, Heike; Nierhaus, Axel; Dartsch, Dorothee C; Kluge, Stefan

2011-08-01

To compare the concentration conformity of infusion solutions manually prepared on intensive care units (ICU) with solutions from pharmacy-based, automated production. A prospective observational study conducted in a university hospital in Germany. Drug concentrations of 100 standardised infusion solutions manually prepared in the ICU and 100 matching solutions from automated production containing amiodarone, noradrenaline or hydrocortisone were measured by high-performance liquid chromatography analysis. Deviations from stated concentrations were calculated, and the quality of achieved concentration conformity of the two production methods was compared. Actual concentrations of 53% of the manually prepared and 16% of the machine-made solutions deviated by >5% above or below the stated concentration. A deviation of >10% was measured in 22% of the manually prepared samples and in 5% of samples from automated production. Of the manually prepared solutions, 15% deviated by >15% above or below the intended concentration. The mean concentration of the manually prepared solutions was 97.2% (SD 12.7%, range 45-129%) and of the machine-made solutions was 101.1% (SD 4.3%, range 90-114%) of the target concentration (p < 0.01). In this preliminary study, ward-based, manually prepared infusion solutions showed clinically relevant deviations in concentration conformity significantly more often than pharmacy-prepared, machine-made solutions. Centralised, automated preparation of standardised infusion solutions may be an effective means to reduce this type of medication error. Further confirmatory studies in larger settings and under conditions of routine automated production are required.

Methods to homogenize electrochemical concentration cell (ECC) ozonesonde measurements across changes in sensing solution concentration or ozonesonde manufacturer

NASA Astrophysics Data System (ADS)

Deshler, Terry; Stübi, Rene; Schmidlin, Francis J.; Mercer, Jennifer L.; Smit, Herman G. J.; Johnson, Bryan J.; Kivi, Rigel; Nardi, Bruno

2017-06-01

Ozone plays a significant role in the chemical and radiative state of the atmosphere. For this reason there are many instruments used to measure ozone from the ground, from space, and from balloons. Balloon-borne electrochemical cell ozonesondes provide some of the best measurements of the ozone profile up to the mid-stratosphere, providing high vertical resolution, high precision, and a wide geographic distribution. From the mid-1990s to the late 2000s the consistency of long-term records from balloon-borne ozonesondes has been compromised by differences in manufacturers, Science Pump (SP) and ENSCI (EN), and differences in recommended sensor solution concentrations, 1.0 % potassium iodide (KI) and the one-half dilution: 0.5 %. To investigate these differences, a number of organizations have independently undertaken comparisons of the various ozonesonde types and solution concentrations, resulting in 197 ozonesonde comparison profiles. The goal of this study is to derive transfer functions to allow measurements outside of standard recommendations, for sensor composition and ozonesonde type, to be converted to a standard measurement and thus homogenize the data to the expected accuracy of 5 % (10 %) in the stratosphere (troposphere). Subsets of these data have been analyzed previously and intermediate transfer functions derived. Here all the comparison data are analyzed to compare (1) differences in sensor solution composition for a single ozonesonde type, (2) differences in ozonesonde type for a single sensor solution composition, and (3) the World Meteorological Organization's (WMO) and manufacturers' recommendations of 1.0 % KI solution for Science Pump and 0.5 % KI for ENSCI. From the recommendations it is clear that ENSCI ozonesondes and 1.0 % KI solution result in higher amounts of ozone sensed. The results indicate that differences in solution composition and in ozonesonde type display little pressure dependence at pressures ≥ 30 hPa, and thus the transfer function can be characterized as a simple ratio of the less sensitive to the more sensitive method. This ratio is 0.96 for both solution concentration and ozonesonde type. The ratios differ at pressures < 30 hPa such that OZ0. 5%/OZ1. 0 % = 0. 90 + 0. 041 ṡ log10(p) and OZSciencePump/OZENSCI = 0. 764 + 0. 133 ṡ log10(p) for p in units of hPa. For the manufacturer-recommended solution concentrations the dispersion of the ratio (SP-1.0 / EN-0.5 %), while significant, is generally within 3 % and centered near 1.0, such that no changes are recommended. For stations which have used multiple ozonesonde types with solution concentrations different from the WMO's and manufacturer's recommendations, this work suggests that a reasonably homogeneous data set can be created if the quantitative relationships specified above are applied to the non-standard measurements. This result is illustrated here in an application to the Nairobi data set.

Bio resorbability of the modified hydroxyapatite in Tris-HCL buffer

NASA Astrophysics Data System (ADS)

Golovanova, O. A.; Izmailov, R. R.; Ghyngazov, S. A.

2016-02-01

The solubility of carbonated hydroxyapatite powders and granulated carbonated hydroxyapatite produced from the synovial biofluid model solution has been studied. The kinetic characteristics of dissolution were determined. It was found that the solubility of carbonated hydroxyapatite is higher as compared to that of hydroxyapatite. The impact of the organic matrix on the rate of sample dissolution was revealed. For HA-gelatin composites, as the gelatin concentration grows, the dissolution rate becomes greater, and a sample of 6.0 g / L concentration has higher resorbability. The results of the research can be used to study the kinetics of dissolution and the biocompatibility of ceramic materials for medicine, namely for reconstructive surgery, dentistry, and development of drug delivery systems.

Dynamic OCT monitoring and quantification of light penetration enhancement for normal, benign and cancerous human lung tissues at different concentrations of glycerol

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

Shu-wen Tan; Ying Jin; Hui Yu

2013-10-31

We have evaluated the dynamic effects of the analyte diffusion on the 1/e light penetration depths of normal, benign and cancerous human lung tissue in vitro, as well as have monitored and quantified the dynamic change in the light penetration depths of the mentioned human lung tissue after application of 25 % and 50 % glycerol solution, respectively. The light penetration depths of the analyte diffusion in the lung tissue are measured using the Fourierdomain optical coherence tomography (FD-OCT). Experimental results show that the application of glycerol as a chemical agent can significantly enhance light penetration depths into the humanmore » normal lung (NL), lung benign granulomatosis (LBG) and lung squamous cell carcinoma (LSCC) tissue. In-depth transport of the glycerol molecules in the NL, LBG and LSCC tissue at a lower glycerol concentration (25 %) are faster than those at a higher glycerol concentration (50 %), and the 1/e light penetration depths at a lower glycerol concentration (25 %) are smaller than those at a higher glycerol concentration (50 %), respectively. Their differences in the maximal 1/e light penetration depths of the NL, LBG and LSCC tissue at a higher and a lower glycerol concentrations were only 8.8 %, 6.8 % and 4.7 %, respectively. (biophotonics)« less

Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

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

Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.

2013-09-05

ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperaturesmore » of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.« less

Observation of glassy state relaxation during annealing of frozen sugar solutions by X-ray computed tomography.

PubMed

Nakagawa, Kyuya; Tamiya, Shinri; Do, Gabsoo; Kono, Shinji; Ochiai, Takaaki

2018-06-01

Glassy phase formation in a frozen product determines various properties of the freeze-dried products. When an aqueous solution is subjected to freezing, a glassy phase forms as a consequence of freeze-concentration. During post-freezing annealing, the relaxation of the glassy phase and the ripening of ice crystals (i.e. Ostwald ripening) spontaneously occur, where the kinetics are controlled by the annealing and glass transition temperatures. This study was motivated to observe the progress of glassy state relaxation separate from ice coarsening during annealing. X-ray computed tomography (CT) was used to observe a frozen and post-freezing annealed solutions by using monochromatized X-ray from the synchrotron radiation. CT images were successfully obtained, and the frozen matrix were analyzed based on the gray level values that were equivalent to the linear X-ray attenuation coefficients of the observed matters. The CT images obtained from rapidly frozen sucrose and dextrin solutions with different concentrations gave clear linear relationships between the linear X-ray attenuation coefficients values and the solute concentrations. It was confirmed that the glassy state relaxation progressed as increasing annealing time, and this trend was larger in the order of the glass transition temperature of the maximally freeze-concentrated phase. The sucrose-water system required nearly 20 h of annealing time at -5 °C for the completion of the glassy phase relaxation, whereas dextrin-water systems required much longer periods because of their higher glass transition temperatures. The trends of ice coarsening, however, did not perfectly correspond to the trends of the relaxation, suggesting that the glassy phase relaxation and Ostwald ripening would jointly control the ice crystal growth/ripening kinetics, and the dominant mechanism differed by the annealing stage. Copyright © 2018 Elsevier B.V. All rights reserved.

Process modelling for materials preparation experiments

NASA Technical Reports Server (NTRS)

Rosenberger, Franz; Alexander, J. Iwan D.

1994-01-01

The main goals of the research under this grant consist of the development of mathematical tools and measurement techniques for transport properties necessary for high fidelity modelling of crystal growth from the melt and solution. Of the tasks described in detail in the original proposal, two remain to be worked on: development of a spectral code for moving boundary problems, and development of an expedient diffusivity measurement technique for concentrated and supersaturated solutions. We have focused on developing a code to solve for interface shape, heat and species transport during directional solidification. The work involved the computation of heat, mass and momentum transfer during Bridgman-Stockbarger solidification of compound semiconductors. Domain decomposition techniques and preconditioning methods were used in conjunction with Chebyshev spectral methods to accelerate convergence while retaining the high-order spectral accuracy. During the report period we have further improved our experimental setup. These improvements include: temperature control of the measurement cell to 0.1 C between 10 and 60 C; enclosure of the optical measurement path outside the ZYGO interferometer in a metal housing that is temperature controlled to the same temperature setting as the measurement cell; simultaneous dispensing and partial removal of the lower concentration (lighter) solution above the higher concentration (heavier) solution through independently motor-driven syringes; three-fold increase in data resolution by orientation of the interferometer with respect to diffusion direction; and increase of the optical path length in the solution cell to 12 mm.

A comparison of methods for deriving solute flux rates using long-term data from streams in the mirror lake watershed

USGS Publications Warehouse

Bukaveckas, P.A.; Likens, G.E.; Winter, T.C.; Buso, D.C.

1998-01-01

Calculation of chemical flux rates for streams requires integration of continuous measurements of discharge with discrete measurements of solute concentrations. We compared two commonly used methods for interpolating chemistry data (time-averaging and flow-weighting) to determine whether discrepancies between the two methods were large relative to other sources of error in estimating flux rates. Flux rates of dissolved Si and SO42- were calculated from 10 years of data (1981-1990) for the NW inlet and Outlet of Mirror Lake and for a 40-day period (March 22 to April 30, 1993) during which we augmented our routine (weekly) chemical monitoring with collection of daily samples. The time-averaging method yielded higher estimates of solute flux during high-flow periods if no chemistry samples were collected corresponding to peak discharge. Concentration-discharge relationships should be used to interpolate stream chemistry during changing flow conditions if chemical changes are large. Caution should be used in choosing the appropriate time-scale over which data are pooled to derive the concentration-discharge regressions because the model parameters (slope and intercept) were found to be sensitive to seasonal and inter-annual variation. Both methods approximated solute flux to within 2-10% for a range of solutes that were monitored during the intensive sampling period. Our results suggest that errors arising from interpolation of stream chemistry data are small compared with other sources of error in developing watershed mass balances.

Small-scale screening method for low-viscosity antibody solutions using small-angle X-ray scattering.

PubMed

Fukuda, Masakazu; Watanabe, Atsushi; Hayasaka, Akira; Muraoka, Masaru; Hori, Yuji; Yamazaki, Tadao; Imaeda, Yoshimi; Koga, Akiko

2017-03-01

In this study, we investigated the concentration range in which self-association starts to form in humanized IgG monoclonal antibody (mAb) solutions. Furthermore, on the basis of the results, we developed a practical method of screening for low-viscosity antibody solutions by using small-angle X-ray scattering (SAXS) measurements utilizing small quantities of samples. With lower-viscosity mAb3, self-association was not detected in the range of 1-80mg/mL. With higher-viscosity mAb1, on the other hand, self-association was detected in the range of 10-20mg/mL and was clearly enhanced by a decrease in temperature. The viscosities of mAb solutions at 160, 180, and 200mg/mL at 25°C quantitatively correlated very well with the particle size parameters obtained by SAXS measurements of mAb solutions at 15mg/mL at 5°C. The quantity of mAb sample required for the SAXS measurements was only 0.15mg, which is about one-hundredth of that required for actual viscosity measurements at a high concentration, and such quantities could be available even at an early stage of development. In conclusion, the SAXS analysis method proposed in this study is a valuable tool for the development of concentrated mAb therapeutics with high manufacturability and high usability for subcutaneous injection. Copyright © 2016 Elsevier B.V. All rights reserved.

Elucidating the Higher Stability of Vanadium (V) Cations in Mixed Acid Based Redox Flow Battery Electrolytes

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

Vijayakumar, M.; Wang, Wei; Nie, Zimin

2013-11-01

The Vanadium (V) cation structures in mixed acid based electrolyte solution were analysed by density functional theory (DFT) based computational modelling and 51V and 35Cl Nuclear Magnetic Resonance (NMR) spectroscopy. The Vanadium (V) cation exists as di-nuclear [V2O3Cl2.6H2O]2+ compound at higher vanadium concentrations (≥1.75M). In particular, at high temperatures (>295K) this di-nuclear compound undergoes ligand exchange process with nearby solvent chlorine molecule and forms chlorine bonded [V2O3Cl2.6H2O]2+ compound. This chlorine bonded [V2O3Cl2.6H2O]2+ compound might be resistant to the de-protonation reaction which is the initial step in the precipitation reaction in Vanadium based electrolyte solutions. The combined theoretical and experimental approachmore » reveals that formation of chlorine bonded [V2O3Cl2.6H2O]2+ compound might be central to the observed higher thermal stability of mixed acid based Vanadium (V) electrolyte solutions.« less

Sequestration of Sr-90 Subsurface Contamination in the Hanford 100-N Area by Surface Infiltration of a Ca-Citrate-Phosphate Solution

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

Szecsody, James E.; Rockhold, Mark L.; Oostrom, Martinus

The objective of this project is to develop a method to emplace apatite precipitate in the 100N vadose zone, which results in sorption and ultimately incorporation of Sr-90 into the apatite structure. The Ca-citrate-PO4 solution can be infiltrated into unsaturated sediments to result in apatite precipitate to provide effective treatment of Sr-90 contamination. Microbial redistribution during solution infiltration and a high rate of citrate biodegradation for river water microbes (water used for solution infiltration) results in a relatively even spatial distribution of the citrate biodegradation rate and ultimately apatite precipitate in the sediment. Manipulation of the Ca-citrate-PO4 solution infiltration strategymore » can be used to result in apatite precipitate in the lower half of the vadose zone (where most of the Sr-90 is located) and within low-K layers (which are hypothesized to have higher Sr-90 concentrations). The most effective infiltration strategy to precipitate apatite at depth (and with sufficient lateral spread) was to infiltrate a high concentration solution (6 mM Ca, 15 mM citrate, 60 mM PO4) at a rapid rate (near ponded conditions), followed by rapid, then slow water infiltration. Repeated infiltration events, with sufficient time between events to allow water drainage in the sediment profile can be used to buildup the mass of apatite precipitate at greater depth. Low-K heterogeneities were effectively treated, as the higher residual water content maintained in these zones resulted in higher apatite precipitate concentration. High-K zones did not receive sufficient treatment by infiltration, although an alternative strategy of air/surfactant (foam) was demonstrated effective for targeting high-K zones. The flow rate manipulation used in this study to treat specific depths and heterogeneities are not as easy to implement at field scale due to the lack of characterization of heterogeneities and difficulty tracking the wetting front over a large subsurface area. However, the use of real-time surface and cross-borehole geophysics can be used to track the infiltrating Ca-citrate-PO4 front so some adjustments can be made in the infiltration rate to precipitate apatite in desired zones. In addition, the reactive transport code used in this study with field scale physical parameters for sediments can be used to evaluate infiltration strategies along with preliminary water infiltration tests at field scale.« less

Determination of activity coefficient of lanthanum chloride in molten LiCl-KCl eutectic salt as a function of cesium chloride and lanthanum chloride concentrations using electromotive force measurements

NASA Astrophysics Data System (ADS)

Bagri, Prashant; Simpson, Michael F.

2016-12-01

The thermodynamic behavior of lanthanides in molten salt systems is of significant scientific interest for the spent fuel reprocessing of Generation IV reactors. In this study, the apparent standard reduction potential (apparent potential) and activity coefficient of LaCl3 were determined in a molten salt solution of eutectic LiCl-KCl as a function of concentration of LaCl3. The effect of adding up to 1.40 mol % CsCl was also investigated. These properties were determined by measuring the open circuit potential of the La-La(III) redox couple in a high temperature molten salt electrochemical cell. Both the apparent potential and activity coefficient exhibited a strong dependence on concentration. A low concentration (0.69 mol %) of CsCl had no significant effect on the measured properties, while a higher concentration (1.40 mol %) of CsCl caused an increase (become more positive) in the apparent potential and activity coefficient at the higher range of LaCl3 concentrations.

PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Efficient solutions for low-temperature singlet-oxygen generators

NASA Astrophysics Data System (ADS)

Igoshin, Valerii I.; Karyshev, V. D.; Katulin, V. A.; Kirilin, A. V.; Kisletsov, A. V.; Konnov, S. A.; Kupriyanov, N. L.; Medvedev, A. M.; Nadezhina, T. N.

1989-02-01

Experimental investigations were made of the physicochemical characteristics of the active solutions for a chemical generator in an oxygen-iodine laser. A strong temperature dependence of the viscosity of the solution was observed. The influence of this factor on the operation of the singlet-oxygen generator and the laser is discussed. The cyclic operation of a laser with efficient neutralization of the reagents and the addition of an alkali is simulated. It is shown that hydrogen peroxide may be 50% utilized when the temperature of the solution is no higher than - 30 °C. A method of preparing a solution for an iodine laser with a low freezing point (between - 30 °C and - 40 °C) is developed. It is shown that an aqueous solution of hydrogen peroxide with a concentration of 25-40% is suitable.

Determination of glucose concentrations using photonic crystal LEDs

NASA Astrophysics Data System (ADS)

Liao, Yu-Yang; Chen, Yung-Tsan; Chang, Cheng-Yu; Lan, Wen-Yi; Huang, Jian-Jang

2016-09-01

As internet of things (IOT) has become a popular topic in current consumer electronics, there is a demand for cost-effective sensors to monitor bio-signals. Traditional optical sensors employ low-dimensional gratings and high-resolution spectrometers to detect the refractive index changes of the solutions. In this work, we develop an alternative approach to correlate the concentration of molecules to the band diagrams of the photonic crystals. A relatively low-resolution spectrum analyzer can be employed, yet achieves higher sensitivity than traditional approaches.

Assessment of well vulnerability for groundwater source protection based on a solute transport model: a case study from Jilin City, northeast China

NASA Astrophysics Data System (ADS)

Huan, Huan; Wang, Jinsheng; Lai, Desheng; Teng, Yanguo; Zhai, Yuanzheng

2015-05-01

Well vulnerability assessment is essential for groundwater source protection. A quantitative approach to assess well vulnerability in a well capture zone is presented, based on forward solute transport modeling. This method was applied to three groundwater source areas (Jiuzhan, Hadawan and Songyuanhada) in Jilin City, northeast China. The ratio of the maximum contaminant concentration at the well to the released concentration at the contamination source ( c max/ c 0) was determined as the well vulnerability indicator. The results indicated that well vulnerability was higher close to the pumping well. The well vulnerability in each groundwater source area was low. Compared with the other two source areas, the cone of depression at Jiuzhan resulted in higher spatial variability of c max/ c 0 and lower minimum c max/ c 0 by three orders of magnitude. Furthermore, a sensitivity analysis indicated that the denitrification rate in the aquifer was the most sensitive with respect to well vulnerability. A process to derive a NO3-N concentration at the pumping well is presented, based on determining the maximum nitrate loading limit to satisfy China's drinking-water quality standards. Finally, the advantages, disadvantages and prospects for improving the precision of this well vulnerability assessment approach are discussed.

Tunable swelling of polyelectrolyte multilayers in cell culture media for modulating NIH-3T3 cells adhesion.

PubMed

Qi, Wei; Cai, Peng; Yuan, Wenjing; Wang, Hua

2014-11-01

For polyelectrolyte multilayers (PEMs) assembled by the layer-by-layer (LbL) assembly technique, their nanostructure and properties can be governed by many parameters during the building process. Here, it was demonstrated that the swelling of the PEMs containing poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) in cell culture media could be tuned with changing supporting salt solutions during the assembly process. Importantly, the influence of the PEMs assembled in different salt solutions on NIH-3T3 cell adhesion was observable. Specifically, the cells could possess a higher affinity for the films assembled in low salt concentration (i.e. 0.15M NaCl) or no salt, the poorly swelling films in cell culture media, which was manifested by the large cell spreading area and focal adhesions. In contrast, those were assembled in higher salt concentration, highly swelling films in cell culture media, were less attractive for the fibroblasts. As a result, the cell adhesion behaviors may be manipulated by tailoring the physicochemical properties of the films, which could be performed by changing the assembly conditions such as supporting salt concentration. Such a finding might promise a great potential in designing desired biomaterials for tissue engineering and regenerative medicine. © 2014 Wiley Periodicals, Inc.

Release of metals from metal-amended soil treated with a sulfosuccinamate surfactant: effects of surfactant concentration, soil/solution ratio, and pH.

PubMed

Hernández-Soriano, Maria del Carmen; Peña, Aránzazu; Dolores Mingorance, Ma

2010-01-01

Anionic surfactants, mainly sulfosuccinamates, can be found in soils as the result of sludge application, wastewater irrigation, and remediation processes. Relatively high concentrations of surfactants together with multimetals can represent an environmental risk. A study was performed to assess the potential of the anionic surfactant Aerosol 22 (A22) for release of Cd, Cu, Pb, and Zn from a metal-amended soil representative of a Mediterranean area. Metal desorption was performed by batch experiments and release kinetics were assessed. Response surface methodology was applied to determine the influence of A22 concentration and the surfactant/soil ratio, as extraction key factors. An increase in solution/soil ratio to 100 (mL g(-1)) caused higher metal release. Leaching predictions found Pb to have the lowest and Cd the highest hazard. Metal release was highly dependent on pH. When extraction was made at pH less than 7, low or negligible amounts of metals were leached, whereas an increase to pH 7 caused desorption rates of 50 to 55% for Cd, Cu, and Zn but only 35% for Pb. Complexed metal-carboxylic groups from A22 were mainly responsible for its higher extractive capacity, especially of Cd and Cu.

Hemocompatibility evaluation in vitro of methoxy polyethyleneglycol-polycaprolactone copolymer solutions.

PubMed

Hu, Qian; Zhang, Yi; Wang, Changyong; Xu, Jiake; Wu, Jianping; Liu, Zonghua; Xue, Wei

2016-03-01

Amphiphilic block copolymer methoxy polyethyleneglycol-polycaprolactone (mPEG-PCL) has attracted interest in the biomedical field, due to its water solubility and biodegradability. Nevertheless, the blood safety of mPEG-PCL copolymers has not been investigated in detail. Because mPEG-PCL copolymers introduced in vivo would inevitably interact with blood tissue, an investigation of possible interactions of mPEG-PCL with key blood components is crucial. We studied the effects of two mPEG-PCL copolymer solutions on blood coagulation, the morphology and lysis of human red blood cells (RBCs), the structure of plasma fibrinogen, complement activation, and platelet aggregation. We found that higher concentrations of the mPEG-PCL copolymers impaired blood clotting, and the copolymers had little impact on the morphology or lysis of RBCs. From the spectroscopy results, the copolymers affected the local microstructure of fibrinogen. The copolymers significantly activated the complement system in a concentration-dependent way. At higher concentrations, the copolymers impaired platelet aggregation, which may have been mediated by an inhibition of the arachidonic acid pathway. These findings provide important information that may be useful for the molecular design and biomedical applications of mPEG-PCL copolymers. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 802-812, 2016. © 2016 Wiley Periodicals, Inc.

Study of structural and optical properties of PbS thin films

NASA Astrophysics Data System (ADS)

Homraruen, T.; Sudswasd, Y.; Sorod, R.; Kayunkid, N.; Yindeesuk, W.

2018-03-01

This research aimed to synthesize lead sulfide (PbS) thin films on glass slides using the successive ion layer absorption and reaction (SILAR) method. We studied the optical properties and structure of PbS thin films by changing the number of dipping cycles and the concentration of precursor solution. The results of this experiment show that different conditions have a considerable influence on the thickness and absorbance of the films. When the number of dipping cycles and the concentration of the solution are increased, film thickness and absorbance tend to become higher. The xrays diffraction pattern showed all the diffraction peaks which confirmed the face center cubic and the structure of PbS had identified. Grain size computation was used to confirm how much these conditions could be affected.

Quaternized wood as sorbent for hexavalent chromium.

PubMed

Low, K S; Lee, C K; Lee, C Y

2001-01-01

The potential of quaternized wood (QW) chips in removing hexavalent chromium from synthetic solution and chrome waste under both batch and continuous-flow conditions was investigated. Sorption was found to be dependent on pH, metal concentration, and temperature. QW chips provide higher sorption capacity and wider pH range compared with untreated wood chips. The equilibrium data could be fitted into the Langmuir isotherm model, and maximum sorption capacities were calculated to be 27.03 and 25.77 mg/g in synthetic chromate solution and chrome waste, respectively. The presence of sulfate in high concentration appeared to suppress the uptake of chromium by QW chips. Column studies showed that bed depth influenced the breakthrough time greatly whereas flow rate of influent had little effect on its sorption on the column.

Controlled release of paclitaxel from a self-assembling peptide hydrogel formed in situ and antitumor study in vitro

PubMed Central

Liu, Jingping; Zhang, Lanlan; Yang, Zehong; Zhao, Xiaojun

2011-01-01

Background A nanoscale injectable in situ-forming hydrogel drug delivery system was developed in this study. The system was based on a self-assembling peptide RADA16 solution, which can spontaneously form a hydrogel rapidly under physiological conditions. We used the RADA16 hydrogel for the controlled release of paclitaxel (PTX), a hydrophobic antitumor drug. Methods The RADA16-PTX suspension was prepared simply by magnetic stirring, followed by atomic force microscopy, circular dichroism analysis, dynamic light scattering, rheological analysis, an in vitro release assay, and a cell viability test. Results The results indicated that RADA16 and PTX can interact with each other and that the amphiphilic peptide was able to stabilize hydrophobic drugs in aqueous solution. The particle size of PTX was markedly decreased in the RADA16 solution compared with its size in water. The RADA16-PTX suspension could form a hydrogel in culture medium, and the elasticity of the hydrogel showed a positive correlation with peptide concentration. In vitro release measurements indicated that hydrogels with a higher peptide concentration had a longer half-release time. The RADA16-PTX hydrogel could effectively inhibit the growth of the breast cancer cell line, MDA-MB-435S, in vitro, and hydrogels with higher peptide concentrations were more effective at inhibiting tumor cell proliferation. The RADA16-PTX hydrogel was effective at controlling the release of PTX and inhibiting tumor cell growth in vitro. Conclusion Self-assembling peptide hydrogels may work well as a system for drug delivery. PMID:22114478

Challenges in Determining Intrinsic Viscosity Under Low Ionic Strength Solution Conditions.

PubMed

Pindrus, Mariya A; Shire, Steven J; Yadav, Sandeep; Kalonia, Devendra S

2017-04-01

To determine the intrinsic viscosity of several monoclonal antibodies (mAbs) under varying pH and ionic strength solution conditions. An online viscosity detector attached to HPLC (Viscotek®) was used to determine the intrinsic viscosity of mAbs. The Ross and Minton equation was used for viscosity prediction at high protein concentrations. Bulk viscosity was determined by a Cambridge viscometer. At 15 mM ionic strength, intrinsic viscosity of the mAbs determined by the single-point approach varied from 5.6 to 6.4 mL/g with changes in pH. High ionic strength did not significantly alter intrinsic viscosity, while a significant increase (up to 24.0 mL/g) was observed near zero mM. No difference in bulk viscosity of mAb3 was observed around pH 6 as a function of ionic strength. Data analysis revealed that near zero mM ionic strength limitations of the single-point technique result in erroneously high intrinsic viscosity. Intrinsic viscosity is a valuable tool that can be used to model baseline viscosity at higher protein concentrations. However, it is not predictive of solution non-ideality at higher protein concentrations. Furthermore, breakdown of numerous assumptions limits the applicability of experimental techniques near zero mM ionic strength conditions. For molecules and conditions studied, the single-point approach produced reliable intrinsic viscosity results at 15 mM. However, this approach must be used with caution near zero mM ionic strength. Data analysis can be used to reveal whether determined intrinsic viscosity is reliable or erroneously high.

Photocatalytic degradation of furfural in aqueous solution by N-doped titanium dioxide nanoparticles.

PubMed

Veisi, Farzaneh; Zazouli, Mohammad Ali; Ebrahimzadeh, Mohammad Ali; Charati, Jamshid Yazdani; Dezfoli, Amin Shiralizadeh

2016-11-01

The photocatalytic degradation of furfural in aqueous solution was investigated using N-doped titanium dioxide nanoparticles under sunlight and ultraviolet radiation (N-TiO 2 /Sun and N-TiO 2 /UV) in a lab-scale batch photoreactor. The N-TiO 2 nanoparticles prepared using a sol-gel method were characterized using XRD, X-ray photoelectron spectroscopy (XPS), and SEM analyses. Using HPLC to monitor the furfural concentration, the effect of catalyst dosage, contact time, initial solution pH, initial furfural concentration, and sunlight or ultraviolet radiation on the degradation efficiency was studied. The efficiency of furfural removal was found to increase with increased reaction time, nanoparticle loading, and pH for both processes, whereas the efficiency decreased with increased furfural concentration. The maximum removal efficiencies for the N-TiO 2 /UV and N-TiO 2 /Sun processes were 97 and 78 %, respectively, whereas the mean removal efficiencies were 80.71 ± 2.08 % and 62.85 ± 2.41 %, respectively. In general, the degradation and elimination rate of furfural using the N-TiO 2 /UV process was higher than that using the N-TiO 2 /Sun process.

The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films

NASA Astrophysics Data System (ADS)

Ren, Jianjun; Zuo, Yu

2012-11-01

The anodizing behavior of aluminum in malonic acid solution and morphology of the anodic films were studied. The voltage-time response for galvanostatic anodization of aluminum in malonic acid solution exhibits a conventional three-stage feature but the formation voltage is much higher. With the increase of electrolyte concentration, the electrolyte viscosity increases simultaneously and the high viscosity decreases the film growth rate. With the concentration increase of the malonic acid electrolyte, the critical current density that initiates local "burning" on the sample surface decreases. For malonic acid anodization, the field-assisted dissolution on the oxide surface is relatively weak and the nucleation of pores is more difficult, which results in greater barrier layer thickness and larger cell dimension. The embryo of the porous structure of anodic film has been created within the linear region of the first transient stage, and the definite porous structure has been established before the end of the first transient stage. The self-ordering behavior of the porous film is influenced by the electrolyte concentration, film thickness and the applied current density. Great current density not only improves the cell arrangement order but also brings about larger cell dimension.

Succinate Functionalization of Hyperbranched Polyglycerol-Coated Magnetic Nanoparticles as a Draw Solute During Forward Osmosis.

PubMed

Yang, Hee-Man; Choi, Hye Min; Jang, Sung-Chan; Han, Myeong Jin; Seo, Bum-Kyoung; Moon, Jei-Kwon; Lee, Kune-Woo

2015-10-01

Hyperbranched polyglycerol-coated magnetic nanoparticles (SHPG-MNPs) were functionalized with succinate groups to form a draw solute for use in a forward osmosis (FO). After the one-step synthesis of hyperbranched polyglycerol-coated magnetic nanoparticles (HPG-MNPs), the polyglycerol groups on the surfaces of the HPG-MNPs were functionalized with succinic anhydride moieties. The resulting SHPG-MNPs showed no change of size and magnetic property compared with HPG-MNPs and displayed excellent dispersibility in water up to the concentration of 400 g/L. SHPG-MNPs solution showed higher osmotic pressure than that of HPG-MNPs solution due to the presence of surface carboxyl groups in SHPG-MNPs and could draw water from a feed solution across an FO membrane without any reverse draw solute leakage during FO process. Moreover, the water flux remained nearly constant over several SHPG-MNP darw solute regeneration cycles applied to the ultrafiltration (UF) process. The SHPG-MNPs demonstrate strong potential for use as a draw solute in FO processes.

Influence of Ca and pH on the uptake and effects of Cd in Folsomia candida exposed to simplified soil solutions.

PubMed

Ardestani, Masoud M; Ortiz, Maria Diez; van Gestel, Cornelis A M

2013-08-01

The present study sought to quantify the components of a biotic ligand model (BLM) for the effects of Cd on Folsomia candida (Collembola). Assuming that soil porewater is the main route of exposure and to exclude the effects of soil particles on metal availability, animals were exposed for 7 d to different Cd concentrations between 0.1 mM and 100 mM in simplified soil solutions at different Ca concentrations (0.2 mM, 0.8 mM, 3.2 mM, and 12.8 mM) or at different pH (5.0, 6.0, and 7.0). Higher Ca concentrations decreased the toxicity of Cd (adult survival) in test solutions, whereas toxicity was slightly lower at pH 7 and 6 than at pH 5, suggesting a mitigating effect of Ca and to a lesser extent pH on Cd toxicity to F. candida. Internal Cd concentrations in the animals increased with increasing exposure level but were significantly reduced by increasing Ca concentrations and were not significantly affected by pH. By using Langmuir isotherms, binding constants for Cd, Ca, and protons and the fraction of binding sites occupied by Cd were calculated and used to predict effects of Cd on survival. Predicted toxicity showed a good agreement with measured responses when Ca and pH were used as separate factors or combined together. The present study shows indications of protective effects of Ca but less of protons on the toxicity and uptake of Cd in F. candida on exposure to simplified soil solutions, which can be described using the principles of a biotic ligand model. Copyright © 2013 SETAC.

Atomic-scale dynamics of edge dislocations in Ni and concentrated solid solution NiFe alloys

DOE PAGES

Zhao, Shijun; Osetsky, Yuri N.; Zhang, Yanwen; ...

2017-01-19

Single-phase concentrated solid solution alloys (CSAs), including high entropy alloys, exhibit excellent mechanical properties compared to conventional dilute alloys. However, the origin of this observation is not clear yet because the dislocation properties in CSAs are poorly understood. In this work, the mobility of a <110>{111} edge dislocation in pure Ni and equiatomic solid solution Ni 0.5Fe 0.5 (NiFe) is studied using molecular dynamics simulations with different empirical potentials. The threshold stress to initiate dislocation movement in NiFe is found to be much higher compared to pure Ni. The drag coefficient of the dislocation motion calculated from the linear regimemore » of dislocation velocities versus applied stress suggests that the movement of dislocations in NiFe is strongly damped compared to that in Ni. The present results indicate that the mobility of edge dislocations in fcc CSAs are controlled by the fluctuations in local stacking fault energy caused by the local variation of alloy composition.« less

Unusual effect of the magnetic field component of the microwave radiation on aqueous electrolyte solutions.

PubMed

Horikoshi, Satoshi; Sumi, Takuya; Serpone, Nick

2012-01-01

The heating characteristics of aqueous electrolyte solutions (NaCl, KCl, CaCl2, NaBF4, and NaBr) of varying concentrations in ultrapure water by 2.45 GHz microwave radiation from a single-mode resonance microwave device and a semiconductor microwave generator were examined under conditions where the electric field (E-field) was dominant and where the magnetic field (H-field) dominated. Although magnetic field heating is not generally used in microwave chemistry, the electrolyte solutions were heated almost entirely by the microwaves' H-field. The heating rates under H-field irradiation at the higher concentrations of electrolytes (0.125 M to 0.50 M) exceeded the rates under E-field irradiation. This inversion phenomenon in heating is described in terms of the penetration depth of the microwaves. On the other hand, the action of the microwave radiation on ethylene glycol containing an electrolyte differed from that observed for water under E-field and H-field conditions.

Poly(methacylic acid-co-maleic acid) grafted nanofibrillated cellulose as a reusable novel heavy metal ions adsorbent.

PubMed

Maatar, Wafa; Boufi, Sami

2015-08-01

A poly(methacrylic acid-co-maleic acid) grafted nanofibrillated cellulose (NFC-MAA-MA) aerogel was prepared via radical polymerization in an aqueous solution using Fenton's reagent. The ensuing aerogel, in the form of a rigid porous material, was characterized by FTIR and NMR and used as an adsorbent for the removal of heavy metals from aqueous solutions. It showed an efficient adsorption, exceeding 95% toward Pb(2+), Cd(2+), Zn(2+) and Ni(2+) when their concentration was lower than 10 ppm and ranged from 90% to 60% for a metal concentration higher than 10 ppm. Over 98% of the adsorbed metal ion was recovered using EDTA as a desorbing solution, and the subsequent washing allowed the aerogel to be reused repeatedly without noticeable loss of adsorption capacity. It was concluded that the (NFC-MAA-MA) aerogel may be used as a high capacity and reusable sorbent material in heavy-metal removing processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ultrasonic accelerates asparagine-glucose non-enzymatic browning reaction without acrylamide formation.

PubMed

Gao, Zhiqiang; Zheng, Junfeng; Chen, Lian

2017-01-01

Ultrasonic accelerated the asparagine-glucose non-enzymatic browning reaction with significant decrease of glucose and asparagine concentrations, and marked increase of intermediate products (UV-absorbance value at 294nm, Abs 294 ), melanoidins (UV-absorbance value at 420nm, Abs 420 ) and in vitro antioxidant activity (DPPH free radical scavenging activity). As the ultrasonic intensity was 17.83W/cm 2 , the asparagine-glucose solution's Abs 294 , Abs 420 and antioxidant activity increased from 0 to 1.26, 0.88 and 21.56%, respectively, and the glucose and asparagine concentrations of the asparagine-glucose solution reduced 58.97 and 12.57%, respectively. The high performance liquid chromatography (HPLC)-Diode Array Detector (DAD) analyses showed that no acrylamide was detected after 50-min ultrasonic reaction. This study suggested that ultrasonic at higher intensity was a potential method to accelerate the non-enzymatic browning reaction in the asparagine-glucose solution without acrylamide production. Copyright © 2016 Elsevier B.V. All rights reserved.

The facile synthesis of a chitosan Cu(II) complex by solution plasma process and evaluation of their antioxidant activities.

PubMed

Ma, Fengming; Li, Pu; Zhang, Baiqing; Wang, Zhenyu

2017-10-01

Synthesis of chitosan-Cu(II) complex by solution plasma process (SPP) irradiation was investigated. The effects of the distance between the electrodes, initial Cu(II) concentration, and initial pH on the Cu(II) adsorption capacity were evaluated. The results showed that narrower distance between the electrodes, higher initial Cu(II) concentration and higher initial pH (at pH<6) were favourable for the adsorption capacity of Cu(II). Characterization of the chitosan-Cu(II) complex by ultraviolet-visible (UV-vis), fourier transform infrared (FT-IR) and electron spin resonance (ESR) spectroscopy revealed that the main structure of chitosan was not changed after irradiation. Thermogravimetry (TG) analysis indicated that Cu(II) ions were well incorporated into the chitosan. The antioxidant activity of the chitosan-Cu(II) complex was evaluated by DPPH, ABTS, and reducing power assays. The chitosan-Cu(II) complex exhibited greater antioxidant activity than the original chitosan. Thus, SPP could be used for preparation of chitosan-Cu(II) complexes. Copyright © 2017. Published by Elsevier B.V.

Adsorption of dimethyl trisulfide from aqueous solution on a low-cost adsorbent: thermally activated pinecone

NASA Astrophysics Data System (ADS)

Shang, Jingge; He, Wei; Fan, Chengxin

2015-01-01

Thermally activated pinecone (TAP) was used for the adsorption of dimethyl trisulfide (DMTS) from aqueous solutions, which was proved to be the main odorous in algae-caused black bloom. The effects of adsorbent dosage, adsorbate concentration and contact time on DMTS biosorption were studied. The TAP produced at 600°C exhibited a relatively high surface area (519.69 m2/g) and excellent adsorption capacity. The results show that the adsorption of DMTS was initially fast and that the equilibrium time was 6 h. Higher initial DMTS concentrations led to lower removal percentages but higher adsorption capacity. The removal percentage of DMTS increased and the adsorption capacity of TAP decreased with an increase in adsorbent dosage. The adsorption process conforms well to a pseudo-second-order kinetics model. The adsorption of DMTS is more appropriately described by the Freundlich isotherm ( R 2 =0.996 1) than by the Langmuir isotherm ( R 2 =0.916 9). The results demonstrate that TAP could be an attractive low-cost adsorbent for removing DMTS from water.

A Novel Procedure for Evaluating the Reinforcing Properties of Tastants in Laboratory Rats: Operant Intraoral Self-administration

PubMed Central

Levy, AnneMarie; Limebeer, Cheryl L.; Ferdinand, Justin; Shillingford, Ucal; Parker, Linda A.; Leri, Francesco

2014-01-01

This paper describes a novel method for studying the bio-behavioral basis of addiction to food. This method combines the surgical component of taste reactivity with the behavioral aspects of operant self-administration of drugs. Under very brief general anaesthesia, rats are implanted with an intraoral (IO) cannula that allows delivery of test solutions directly in the oral cavity. Animals are then tested in operant self-administration chambers whereby they can press a lever to receive IO infusions of test solutions. IO self-administration has several advantages over experimental procedures that involve drinking a solution from a spout or operant responding for solid pellets or solutions delivered in a receptacle. Here, we show that IO self-administration can be employed to study self-administration of high fructose corn syrup (HFCS). Rats were first tested for self-administration on a progressive ratio (PR) schedule, which assesses the maximum amount of operant behavior that will be emitted for different concentrations of HFCS (i.e. 8%, 25%, and 50%). Following this test, rats self-administered these concentrations on a continuous schedule of reinforcement (i.e. one infusion for each lever press) for 10 consecutive days (1 session/day; each lasting 3 hr), and then they were retested on the PR schedule. On the continuous reinforcement schedule, rats took fewer infusions of higher concentrations, although the lowest concentration of HFCS (8%) maintained more variable self-administration. Furthermore, the PR tests revealed that 8% had lower reinforcing value than 25% and 50%. These results indicate that IO self-administration can be employed to study acquisition and maintenance of responding for sweet solutions. The sensitivity of the operant response to differences in concentration and schedule of reinforcement makes IO self-administration an ideal procedure to investigate the neurobiology of voluntary intake of sweets. PMID:24561923

Chemical Potentials, Activity Coefficients, and Solubility in Aqueous NaCl Solutions: Prediction by Polarizable Force Fields.

PubMed

Moučka, Filip; Nezbeda, Ivo; Smith, William R

2015-04-14

We describe a computationally efficient molecular simulation methodology for calculating the concentration dependence of the chemical potentials of both solute and solvent in aqueous electrolyte solutions, based on simulations of the salt chemical potential alone. We use our approach to study the predictions for aqueous NaCl solutions at ambient conditions of these properties by the recently developed polarizable force fields (FFs) AH/BK3 of Kiss and Baranyai (J. Chem. Phys. 2013, 138, 204507) and AH/SWM4-DP of Lamoureux and Roux (J. Phys. Chem. B 2006, 110, 3308 - 3322) and by the nonpolarizable JC FF of Joung and Cheatham tailored to SPC/E water (J. Phys. Chem. B 2008, 112, 9020 - 9041). We also consider their predictions of the concentration dependence of the electrolyte activity coefficient, the crystalline solid chemical potential, the electrolyte solubility, and the solution specific volume. We first highlight the disagreement in the literature concerning calculations of solubility by means of molecular simulation in the case of the JC FF and provide strong evidence of the correctness of our methodology based on recent independently obtained results for this important test case. We then compare the predictions of the three FFs with each other and with experiment and draw conclusions concerning their relative merits, with particular emphasis on the salt chemical potential and activity coefficient vs concentration curves and their derivatives. The latter curves have only previously been available from Kirkwood-Buff integrals, which require approximate numerical integrations over system pair correlation functions at each concentration. Unlike the case of the other FFs, the AH/BK3 curves are nearly parallel to the corresponding experimental curves at moderate and higher concentrations. This leads to an excellent prediction of the water chemical potential via the Gibbs-Duhem equation and enables the activity coefficient curve to be brought into excellent agreement with experiment by incorporating an appropriate value of the standard state chemical potential in the Henry Law convention.

Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution.

PubMed

Liu, Yueqiang; Phenrat, Tanapon; Lowry, Gregory V

2007-11-15

Nanoscale zero-valent iron (NZVI) is used to remediate contaminated groundwater plumes and contaminant source zones. The target contaminant concentration and groundwater solutes (NO3-, Cl-, HCO3-, SO4(2-), and HPO4(2-)) should affect the NZVI longevity and reactivity with target contaminants, but these effects are not well understood. This study evaluates the effect of trichloroethylene (TCE) concentration and common dissolved groundwater solutes on the rates of NZVI-promoted TCE dechlorination and H2 evolution in batch reactors. Both model systems and real groundwater are evaluated. The TCE reaction rate constant was unaffected by TCE concentration for [TCE] < or = 0.46 mM and decreased by less than a factor of 2 for further increases in TCE concentration up to water saturation (8.4 mM). For [TCE] > or = 0.46 mM, acetylene formation increased, and the total amount of H2 evolved at the end of the particle reactive lifetime decreased with increasing [TCE], indicating a higher Fe0 utilization efficiency for TCE dechlorination. Common groundwater anions (5mN) had a minor effect on H2 evolution but inhibited TCE reduction up to 7-fold in increasing order of Cl- < SO4(2-) < HCO3- < HPO4(2). This order is consistent with their affinity to form complexes with iron oxide. Nitrate, a NZVI-reducible groundwater solute, present at 0.2 and 1 mN did not affect the rate of TCE reduction but increased acetylene production and decreased H2 evolution. NO3- present at > 3 mM slowed TCE dechlorination due to surface passivation. NO3- present at 5 mM stopped TCE dechlorination and H2 evolution after 3 days. Dissolved solutes accounted for the observed decrease of NZVI reactivity for TCE dechlorination in natural groundwater when the total organic content was small (< 1 mg/L).

IMPACT OF CRITICAL ANION SOIL SOLUTION CONCENTRATION ON ALUMINUM ACTIVITY IN ALPINE TUNDRA SOIL Andrew Evans, Jr.1 , Michael B. Jacobs2, and Jason R. Janke1, (1) Metropolitan State University of Denver, Dept. of Earth and Atmospheric Sciences, (2) Dept. of Chemistry, Denver, CO, United States.

NASA Astrophysics Data System (ADS)

Evans, A.

2015-12-01

Soil solution anionic composition can impact both plant and microbial activity in alpine tundra soils by altering biochemical cycling within the soil, either through base cation leaching, or shifts in aluminum controlling solid phases. Although anions play a critical role in the aqueous speciation of metals, relatively few high altitude field studies have examined their impact on aluminum controlling solid phases and aluminum speciation in soil water. For this study, thirty sampling sites were selected on Trail Ridge Road in Rocky Mountain National Park, Estes Park, CO, and sampled during July, the middle of the growing season. Sampling elevations ranged from approximately 3560 - 3710 m. Soil samples were collected to a depth of 15.24 cm, and the anions were extracted using a 2:1 D.I. water to soil ratio. Filtered extracts were analyzed using IC and ICP-MS. Soil solution NO3- concentrations were significantly higher for sampling locations east of Iceberg Pass (EIBP) (mean = 86.94 ± 119.8 mg/L) compared to locations west of Iceberg Pass (WIBP) (mean 1.481 ± 2.444 mg/L). Both F- and PO43- soil solution concentrations, 0.533 and 0.440 mg/L, respectively, were substantially lower, for sampling sites located EIBP, while locations WIBP averaged 0.773 and 0.829 mg/L respectively, for F- and PO43-. Sulfate concentration averaged 3.869 ± 3.059 mg/L for locations EIBP, and 3.891 ± 3.1970 for locations WIBP. Geochemical modeling of Al3+ in the soil solution indicated that a suite of aluminum hydroxyl sulfate minerals controlled Al3+ activity in the alpine tundra soil, with shifts between controlling solid phases occurring in the presence of elevated F- concentrations.

Calcium Solubility and Cation Exchange Properties in Zeoponic Soil

NASA Technical Reports Server (NTRS)

Beiersdorfer, Raymond E.

1999-01-01

An important aspect of a regenerative life support system at a Lunar or Martian outpost is the ability to produce food. Essential plant nutrients, as well as a solid support substrate, can be provided by: (1) treated Lunar or Martian regolith; (2) a synthetic soil or (3) some combination of both. A synthetic soil composed of ammonium- and potassium-saturated chinoptlolite (a zeolite mineral) and apatite, can provide slow-release fertilization of plants via dissolution and ion-exchange reactions. Previous equilibrium studies (Beiersdorfer, 1997) on mixtures of synthetic hydroxyapatite and saturated-clinoptilolite indicate that the concentrations of macro-nutrients such as ammonium, phosphorous, potassium, magnesium, and calcium are a function of the ratio of chinoptilolite to apatite in the sample and to the ratio of potassium to ammonium on the exchange sites in the clinoptilolite. Potassium, ammonium, phosphorous, and magnesium are available to plants at sufficient levels. However, calcium is deficient, due to the high degree of calcium adsorption by the clinoptilolite. Based on a series of batch-equilibration experiments, this calcium deficiency can be reduced by (1) treating the clinoptilolite with CaNO3 or (2) adding a second Ca-bearing mineral (calcite, dolomite or wollastonite) to the soil. Treating the Cp with CaNO3 results in increased Ca in solution, decreased P in solution and decreased NH4 in solution. Concentrations of K were not effected by the CaNO3 treatment. Additions of Cal, Dol and Wol changed the concentrations of Ca and P in solution in a systematic fashion. Cal has the greatest effect, Dol the least and Wol is intermediate. The changes are consistent with changes expected for a common ion effect with Ca. Higher concentrations of Ca in solution with added Cal, Dol or Wol do not result in changes in K or NH4 concentrations.

Evidence that elevated CO2 levels can indirectly increase rhizosphere denitrifier activity

NASA Technical Reports Server (NTRS)

Smart, D. R.; Ritchie, K.; Stark, J. M.; Bugbee, B.

1997-01-01

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, as determined by a nitrogen mass balance, increased with elevated CO2 levels in the shoot environment and with a high NO3- concentration in the rooting zone. These results indicated that aerial CO2 concentration can play a role in rhizosphere denitrifier activity.

Synthesis, characterization and application of ion exchange resin as a slow-release fertilizer for wheat cultivation in space

NASA Astrophysics Data System (ADS)

Li, Bowei; Dong, Chen; Chu, Zhengpei; Zhang, Weizhe; Wang, Minjuan; Liu, Hong; Xie, Beizhen

2016-10-01

In addition to the bio-regenerative air revitalization, water recycling and waste management systems and their associated challenges, enhancing the crop yield with less fertilizer input for sustainable food production in space is also a challenge that needs to be overcome. The purpose of this study is to investigate the feasibility of applying ion exchange resin as a slow-release fertilizer for wheat cultivation in space. Strong-acid cationic exchange resins and weak-base anion exchange resins soaked in 1X, 5X, 10X and 15X Hoagland nutrient solutions, respectively, were used as fertilizers in clinoptilolite to cultivate wheat plants, and the morphological and physiological characteristics of the wheat plants were studied and compared with that of the wheat planted in vermiculite and nutrient solutions. The results showed that more ions were attached on the surface of the ion exchange resins as the solution concentration increased. After 14 days, the fresh weight of wheat planted in the ion exchange resin-clinoptilolite (IER-clinoptilolite) treated with 10X and 15X solutions were 190% and 192% higher than that of wheat planted in nutrient solution with the same concentration. Chlorophyll content of wheat plants cultivated in the two kinds of solid medium is significantly higher than that of liquid cultivation. The lowest peroxidase (POD) activity and malondialdehyde (MDA) contents of wheat plants cultivated in the IER-clinoptilolite appeared on the 14th day. According to all the experimental data, it's promising to produce slow-release nutrient fertilizer by using strong-acid cationic exchange resins and weak-base anion exchange resins for wheat cultivation in space.

Combination of surfactant enhanced soil washing and electro-Fenton process for the treatment of soils contaminated by petroleum hydrocarbons.

PubMed

Huguenot, David; Mousset, Emmanuel; van Hullebusch, Eric D; Oturan, Mehmet A

2015-04-15

In order to improve the efficiency of soil washing treatment of hydrocarbon contaminated soils, an innovative combination of this soil treatment technique with an electrochemical advanced oxidation process (i.e. electro-Fenton (EF)) has been proposed. An ex situ soil column washing experiment was performed on a genuinely diesel-contaminated soil. The washing solution was enriched with surfactant Tween 80 at different concentrations, higher than the critical micellar concentration (CMC). The impact of soil washing was evaluated on the hydrocarbons concentration in the leachates collected at the bottom of the soil columns. These eluates were then studied for their degradation potential by EF treatment. Results showed that a concentration of 5% of Tween 80 was required to enhance hydrocarbons extraction from the soil. Even with this Tween 80 concentration, the efficiency of the treatment remained very low (only 1% after 24 h of washing). Electrochemical treatments performed thereafter with EF on the collected eluates revealed that the quasi-complete mineralization (>99.5%) of the hydrocarbons was achieved within 32 h according to a linear kinetic trend. Toxicity was higher than in the initial solution and reached 95% of inhibition of Vibrio fischeri bacteria measured by Microtox method, demonstrating the presence of remaining toxic compounds even after the complete degradation. Finally, the biodegradability (BOD₅/COD ratio) reached a maximum of 20% after 20 h of EF treatment, which is not enough to implement a combined treatment with a biological treatment process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Binding and Leakage of Barium in Alginate Microbeads

PubMed Central

Mørch, Yrr A.; Qi, Meirigeng; Gundersen, Per Ole M.; Formo, Kjetil; Lacik, Igor; Skjåk-Bræk, Gudmund; Oberholzer, Jose; Strand, Berit L.

2013-01-01

Microbeads of alginate cross-linked with Ca2+ and/or Ba2+ are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared to high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. In order to reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. PMID:22700168

Binding and leakage of barium in alginate microbeads.

PubMed

Mørch, Yrr A; Qi, Meirigeng; Gundersen, Per Ole M; Formo, Kjetil; Lacik, Igor; Skjåk-Braek, Gudmund; Oberholzer, Jose; Strand, Berit L

2012-11-01

Microbeads of alginate crosslinked with Ca(2+) and/or Ba(2+) are popular matrices in cell-based therapy. The aim of this study was to quantify the binding of barium in alginate microbeads and its leakage under in vitro and accumulation under in vivo conditions. Low concentrations of barium (1 mM) in combination with calcium (50 mM) and high concentrations of barium (20 mM) in gelling solutions were used for preparation of microbeads made of high-G and high-M alginates. High-G microbeads accumulated barium from gelling solution and contained higher concentrations of divalent ions for both low- and high-Ba exposure compared with high-G microbeads exposed to calcium solely and to high-M microbeads for all gelling conditions. Although most of the unbound divalent ions were removed during the wash and culture steps, leakage of barium was still detected during storage. Barium accumulation in blood and femur bone of mice implanted with high-G beads was found to be dose-dependent. Estimated barium leakage relevant to transplantation to diabetic patients with islets in alginate microbeads showed that the leakage was 2.5 times lower than the tolerable intake value given by WHO for high-G microbeads made using low barium concentration. The similar estimate gave 1.5 times higher than is the tolerable intake value for the high-G microbeads made using high barium concentration. To reduce the risk of barium accumulation that may be of safety concern, the microbeads made of high-G alginate gelled with a combination of calcium and low concentration of barium ions is recommended for islet transplantation. Copyright © 2012 Wiley Periodicals, Inc.

The effect of urea on refractometric total protein measurement in dogs and cats with azotemia.

PubMed

Legendre, Kelsey P; Leissinger, Mary; Le Donne, Viviana; Grasperge, Britton J; Gaunt, Stephen D

2017-03-01

While protein is the predominant solute measured in plasma or serum by a refractometer, nonprotein substances also contribute to the angle of refraction. There is debate in the current literature regarding which nonprotein substances cause factitiously high refractometric total protein measurements, as compared to the biuret assay. The purpose of the study was to determine if the blood of azotemic animals, specifically with increased blood urea concentration, will have significantly higher refractometric total protein concentrations compared to the total protein concentrations measured by biuret assay. A prospective case series was conducted by collecting data from azotemic (n = 26) and nonazotemic (n = 34) dogs and cats. In addition, an in vitro study was performed where urea was added to an enhanced electrolyte solution at increasing concentrations, and total protein was assessed by both the refractometer and spectrophotometer. Statistical analysis was performed to determine the effect of urea. The refractometric total protein measurement showed a positive bias when compared to the biuret protein measurement in both groups, but the bias was higher in the azotemic group vs the nonazotemic group. The mean difference in total protein measurements of the nonazotemic group (0.59 g/dL) was significantly less (P < .01) than the mean difference of the azotemic group (0.95 g/dL). The in vitro experiment revealed a positive bias with a proportional error. This study demonstrated that increasing concentrations of urea significantly increased the total protein concentration measured by the refractometer as compared to the biuret assay, both in vivo and in vitro. © 2017 American Society for Veterinary Clinical Pathology.

Effects of cadmium concentration on ozone-induced phytotoxicity in cress

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

Czuba, M.; Ormrod, D.P.

1974-01-01

Cadmium solutions at concentrations of 0, 10, 40, 100, 500 or 1000 ppm were applied to the soil around cress (Lepidium sativum L. cv. Fine Curled) every 4th day for several weeks. Four week old plants were fumigated once at ozone levels of 0, 5, 10, 20, 25 or 30-35 pphm for 6 hours. Plants that had received higher concentrations of cadmium showed markedly increased sensitivity to ozone in terms of visible leaf damage after ozone treatment. Plants receiving cadmium solution alone or those receiving ozone treatment alone either did not show leaf damage or as much leaf damage asmore » plants which had received both treatments. Mineral analyses of plant tissues showed the relationship between tissue content of both essential and toxic cations and the sensitivity of the plant to various ozone levels. Pigment analyses showed changes in chlorophyll amounts and ratios between treatments. Statistical analyses of data for morphological parameters showed that there is an interaction between Cd and ozone treatments over a range of concentrations.« less

Adsorption of heavy metal ions by sawdust of deciduous trees.

PubMed

Bozić, D; Stanković, V; Gorgievski, M; Bogdanović, G; Kovacević, R

2009-11-15

The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g(-1) of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu(2+) ions but it is very low for Fe(2+) ions, not exceeding 10%.

Hindered Diffusion in Polymeric Solutions Studied by Fluorescence Correlation Spectroscopy

PubMed Central

Zustiak, Silviya P.; Nossal, Ralph; Sackett, Dan L.

2011-01-01

Diffusion of molecules in the crowded and charged interior of the cell has long been of interest for understanding cellular processes. Here, we introduce a model system of hindered diffusion that includes both crowding and binding. In particular, we obtained the diffusivity of the positively charged protein, ribonuclease A (RNase), in solutions of dextrans of various charges (binding) and concentrations (crowding), as well as combinations of both, in a buffer of physiological ionic strength. Using fluorescence correlation spectroscopy, we observed that the diffusivity of RNase was unaffected by the presence of positively charged or neutral dextrans in the dilute regime but was affected by crowding at higher polymer concentrations. Conversely, protein diffusivity was significantly reduced by negatively charged dextrans, even at 0.4 μM (0.02% w/v) dextran. The diffusivity of RNase decreased with increasing concentrations of negative dextran, and the amount of bound RNase increased until it reached a plateau of ∼80% bound RNase. High salt concentrations were used to establish the electrostatic nature of the binding. Binding of RNase to the negatively charged dextrans was further confirmed by ultrafiltration. PMID:21723836

Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands.

PubMed

Li, Peng; Zhun, Bao; Wang, Xuegang; Liao, PingPing; Wang, Guanghui; Wang, Lizhang; Guo, Yadan; Zhang, Weimin

2017-12-19

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH < 3.0, and the following iron-electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 μmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.

Adsorption and fractionation of a muck fulvic acid on kaolinite and goethite at pH 3.7,6, and 8

USGS Publications Warehouse

Namjesnik-Dejanovic, K.; Maurice, P.A.; Aiken, G.R.; Cabaniss, S.; Chin, Y.-P.; Pullin, M.J.

2000-01-01

Molecular weight (MW) of humic materials is a key factor controlling proton and metal binding and organic pollutant partitioning. Several studies have suggested preferential adsorption of higher MW, more aromatic moieties to mineral surfaces; quantification of such processes is fundamental to development of predictive models. We used high pressure size exclusion chromatography (HPSEC) to quantify MW changes upon adsorption of a muck fulvic acid (MFA) extracted from a peat deposit to kaolinite and goethite, at pH 3.7,6, and 8 at 22 ??C, I = 0.01 (NaC1), 24-h reaction time. MFA adsorption affinity was greater for goethite than for kaolinite. At concentrations less than the adsorption maximum (A(max)) for both adsorbents, the weight-average MW (M(w)) of MFA remaining in solution decreased by as much as several hundred Daltons relative to control samples, indicating preferential adsorption of the higher MW components. At concentrations more than A(max), M(w) of MFA in solution did not change appreciably. Although total adsorption decreased significantly as pH increased, fractionation as measured by change in M(w) remained similar, perhaps indicating greater selectivity for higher MW components at higher pH. Absorptivities at ?? = 280 nm normalized to mg C L-1 (??) suggested preferential adsorption of more aromatic moieties to kaolinite. ?? could not be used for goethite-reacted samples because high Fe concentrations in the aqueous phase brought about by goethite dissolution interfered with the spectroscopic analysis. Preliminary kinetic experiments suggested that smaller molecules adsorbed first and were replaced by larger molecules whose adsorption was thermodynamically favored.

Nature and consequences of protein-protein interactions in high protein concentration solutions.

PubMed

Saluja, Atul; Kalonia, Devendra S

2008-06-24

High protein concentration solutions are becoming increasingly important in the pharmaceutical industry. The solution behavior of proteins at high concentrations can markedly differ from that predicted based on dilute solution analysis due to thermodynamic non-ideality in these solutions. The non-ideality observed in these systems is related to the protein-protein interactions (PPI). Different types of forces play a key role in determining the overall nature and extent of these PPI and their relative contributions are affected by solute and solvent properties. However, individual contributions of these forces to the solution properties of concentrated protein solutions are not fully understood. The role of PPI, driven by these intermolecular forces, in governing solution rheology and physical stability of high protein concentration solutions is discussed from the point of view of pharmaceutical product development. Investigation of protein self-association and aggregation in concentrated protein solutions is crucial for ensuring the safety and efficacy of the final product for the duration of the desired product shelf life. Understanding rheology of high concentration protein solutions is critical for addressing issues during product manufacture and administration of final formulation to the patient. To this end, analysis of solution viscoelastic character can also provide an insight into the nature of PPI affecting solution rheology.

Trends in the short-term release of fission products and actinides to aqueous solution from used CANDU fuels at elevated temperature

NASA Astrophysics Data System (ADS)

Stroes-Gascoyne, S.

1992-08-01

A large number of short-term leaching experiments has been performed to determine fission product and actinide release from used CANDU (CANada Deuterium Uranium) fuels and to establish which factors affect release. Results are reported after30 ± 10 d leaching at 100-150°C under oxidizing (air) or reducing (Ar-3% H 2 or Ar) conditions, in various synthetic groundwaters. Cesium-137 release (0.007-6%) was positively correlated with increases in fuel power, leachant temperature and ionic strength. Strontium-90 release (0.0003-0.3%) generally increased with ionic strength, higher temperature and redox conditions. Actinide and Tc concentrations were compared to ranges calculated with a thermodynamic equilibrium model, that accounts for the uncertain geochemical parameters of a nuclear waste vault by calculating concentration ranges based on 40000 hypothetical cases. Experimental U concentrations (10 -8.5 to 10 -3 mol/kg) were higher than the model range, probably because of higher redox potentials in the experiments. Measured Pu concentrations (10 -12.5 to 10 -7 mol/kg) were at the low end of the calculated range. Americium and Cm concentrations (10 -12.5 to 10 -7 and 10 -15 to 10 -9 mol/kg, respectively) were highest under oxidizing conditions and higher temperatures. Technetium-99 concentrations (10 -5.5 to 10 -10.5 mol/kg) covered a much narrower range than calculated by the model.

Dipsogenic and feeding influences of intraventricularly infused anionic choline solutions.

PubMed

Mandal, M B; Badgaiyan, R D

1991-10-01

Chloride and bicarbonate solutions of choline were infused into the anteroventral part of the third ventricle of two different groups of rats through chronically implanted stainless steel cannulae. Dipsogenic and feeding responses elicited by these solutions were studied by observations taken at half hour intervals up to two h and then, after 24 h of infusions. Results were compared with the control response evoked by similar infusion of artificial cerebrospinal fluid (aCSF). Food and water intakes were recorded in different groups (n = 18 each) of rats. Dipsogenic response elicited by choline chloride solution in the observation taken 24 h after infusion, however, was higher only as compared to the control. Dipsogenic effect of bicarbonate solution was not significantly different from the control in the first two observations (30 and 60 min), but in the later observations (90, 120 min and 24 h), it was significantly higher. None of the choline solutions significantly alter feeding response within 2 h of infusions. However, in the observation taken 24 h after infusion, the response evoked by choline chloride was greater than that elicited by aCSF. The results support our earlier observation that chloride concentration of third ventricular CSF significantly influences water and food consumption. Intraventricularly administered choline also appears to have positive influence on these behaviors.

Competitive Binding to Cuprous Ions of Protein and BCA in the Bicinchoninic Acid Protein Assay

PubMed Central

Huang, Tao; Long, Mian; Huo, Bo

2010-01-01

Although Bicinchoninic acid (BCA) has been widely used to determine protein concentration, the mechanism of interaction between protein, copper ion and BCA in this assay is still not well known. Using the Micro BCA protein assay kit (Pierce Company), we measured the absorbance at 562 nm of BSA solutions with different concentrations of protein, and also varied the BCA concentration. When the concentration of protein was increased, the absorbance exhibited the known linear and nonlinear increase, and then reached an unexpected plateau followed by a gradual decrease. We introduced a model in which peptide chains competed with BCA for binding to cuprous ions. Formation of the well-known chromogenic complex of BCA-Cu1+-BCA was competed with the binding of two peptide bonds (NTPB) to cuprous ion, and there is the possibility of the existence of two new complexes. A simple equilibrium equation was established to describe the correlations between the substances in solution at equilibrium, and an empirical exponential function was introduced to describe the reduction reaction. Theoretical predictions of absorbance from the model were in good agreement with the measurements, which not only validated the competitive binding model, but also predicted a new complex of BCA-Cu1+-NTPB that might exist in the final solution. This work provides a new insight into understanding the chemical bases of the BCA protein assay and might extend the assay to higher protein concentration. PMID:21625379

Foam-assisted delivery of nanoscale zero valent iron in porous media

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

Ding, Yuanzhao; Liu, Bo; Shen, Xin

2013-09-01

Foam is potentially a promising vehicle to deliver nanoparticles for vadose zone remediation as foam can overcome the intrinsic problems associated with solution-based delivery, such as preferential flow and contaminant mobilization. In this work, the feasibility of using foam to deliver nanoscale zero valent iron (nZVI) in unsaturated porous media was investigated. Foams generated using surfactant sodium lauryl ether sulfate (SLES) showed excellent ability to carry nZVI. SLES and nZVI concentrations in the foaming solutions did not affect the percentages of nZVI concentrations in foams relative to nZVI concentrations in the solutions. When foams carrying nZVI were injected through themore » unsaturated columns, the fractions of nZVI exiting the column were much higher than those when nZVI was injected in liquid. The enhanced nZVI transport implies that foam delivery could significantly increase the radius of influence of injected nZVI. The type and concentrations of surfactants and the influent nZVI concentrations did not noticeably affect nZVI transport during foam delivery. In contrast, nZVI retention increased considerably as the grain size of porous media decreased. Oxidation of foam-delivered nZVI due to oxygen diffusion into unsaturated porous media was visually examined using a flow cell. It was demonstrated that if foams are injected to cover a deep vadose zone layer, oxidation would only cause a small fraction of foam-delivered nZVI to be oxidized before it reacts with contaminants.« less

In Vitro Evaluation of Novel Phenytoin-Loaded Alkyd Nanoemulsions Designed for Application in Topical Wound Healing.

PubMed

Teo, Siew Yong; Yew, Mei Yeng; Lee, Siang Yin; Rathbone, Michael J; Gan, Seng Neon; Coombes, Allan G A

2017-01-01

Phenytoin-loaded alkyd nanoemulsions were prepared spontaneously using the phase inversion method from a mixture of novel biosourced alkyds and Tween 80 surfactant. Exposure of human adult keratinocytes (HaCaT cells) for 48 h to alkyd nanoemulsions producing phenytoin concentrations of 3.125-200 μg/mL resulted in relative cell viability readings using tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide of 100% confirming nontoxicity and suggesting cell proliferation activity. Phenytoin-loaded alkyd nanoemulsions generally resulted in higher mean cell viability compared with equivalent concentration of phenytoin solutions, suggesting that the nanoemulsions provided a controlled-release property that maintained the optimum phenytoin level for keratinocyte growth. HaCaT cell proliferation, measured by 5-bromo-2-deoxyuridine uptake, was found to increase following exposure to increasing phenytoin concentration from 25 to 50 μg/mL in solution or encapsulated in nanoemulsions but declined at a drug concentration of 100 μg/mL. An in vitro cell monolayer wound scratch assay revealed that phenytoin solution or nanoemulsions producing 50 μg/mL phenytoin concentration resulted in 75%-82% "scratch closure" after 36 h, similar to medium containing 10% fetal bovine serum as a cell growth promoter. These findings indicate that phenytoin-loaded alkyd nanoemulsions show potential for promoting topical wound healing through enhanced proliferation of epidermal cells. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Treatment of neonatal calf diarrhea with an oral electrolyte solution supplemented with psyllium mucilloid.

PubMed

Cebra, M L; Garry, F B; Cebra, C K; Adams, R; McCann, J P; Fettman, M J

1998-01-01

Dairy calves under 14 days of age with naturally occurring, uncomplicated diarrhea were treated for 3 days with a hypertonic oral electrolyte solution with (n = 15) or without (n = 12) psyllium. Clinical response and clinical pathology data were compared between the 2 groups. Glucose absorption was evaluated on days 1 and 3 by measurement of plasma glucose and lactate and serum insulin concentrations for 4 hours after formula administration. On day 1, glucose, lactate, and insulin concentrations were lower in psyllium-fed calves than in control calves, with significant differences noted in glucose and lactate concentrations at several time points (P < 0.05). Plasma lactate concentrations were higher at several times in both treatment groups on day 3 than on day 1 (P < 0.05). Fecal consistency was markedly different in psyllium-fed calves as compared with control calves within 24 hours of psyllium supplementation. Fecal percent dry matter content was lower in psyllium-fed calves than in control calves at least once a day during supplementation and on day 3 compared with day 0 in the psyllium-fed calves (P < 0.05). There were no significant differences in clinical performance scores, hydration status, arterial blood gas, serum anion gap, electrolyte, or total CO2 concentrations. Addition of psyllium to an oral electrolyte solution resulted in immediate alterations in glucose absorption without impairing rehydration in diarrheic calves, but differences were transient and did not affect clinical outcome.

Structure and aggregation in model tetramethylurea solutions

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

Gupta, Rini; Patey, G. N., E-mail: patey@chem.ubc.ca

The structure of model aqueous tetramethylurea (TMU) solutions is investigated employing large-scale (32 000, 64 000 particles) molecular dynamics simulations. Results are reported for TMU mole fractions, X{sub t}, ranging from infinite dilution up to 0.07, and for two temperatures, 300 and 330 K. Two existing force fields for TMU-water solutions are considered. These are the GROMOS 53A6 united-atom TMU model combined with SPC/E water [TMU(GROMOS-UA)/W(SPC/E)], and the more frequently employed AMBER03 all-atom force field for TMU combined with the TIP3P water model [TMU(AMBER-AA)/W(TIP3P)]. It is shown that TMU has a tendency towards aggregation for both models considered, but the tendency ismore » significantly stronger for the [TMU(AMBER-AA)/W(TIP3P)] force field. For this model signs of aggregation are detected at X{sub t} = 0.005, aggregation is a well established feature of the solution at X{sub t} = 0.02, and the aggregates increase further in size with increasing concentration. This is in agreement with at least some experimental studies, which report signals of aggregation in the low concentration regime. The TMU aggregates exhibit little structure and are simply loosely ordered, TMU-rich regions of solution. The [TMU(GROMOS-UA)/W(SPC/E)] model shows strong signs of aggregation only at higher concentrations (X{sub t} ≳ 0.04), and the aggregates appear more loosely ordered, and less well-defined than those occurring in the [TMU(AMBER-AA)/W(TIP3P)] system. For both models, TMU aggregation increases when the temperature is increased from 300 to 330 K, consistent with an underlying entropy driven, hydrophobic interaction mechanism. At X{sub t} = 0.07, the extra-molecular correlation length expected for microheterogeneous solutions has become comparable with the size of the simulation cell for both models considered, indicating that even the systems simulated here are sufficiently large only at low concentrations.« less

Stability of 10 mg/mL cefuroxime solution for intracameral injection in commonly used polypropylene syringes and new ready-to-use cyclic olefin copolymer sterile vials using the LC-UV stability-indicating method.

PubMed

Feutry, Frédéric; Simon, Nicolas; Genay, Stéphanie; Lannoy, Damien; Barthélémy, Christine; Décaudin, Bertrand; Labalette, Pierre; Odou, Pascal

2016-01-01

Injecting intracameral cefuroxime has been found beneficial in reducing the risk of postoperative endophthalmitis but its use has been limited through a lack of approved marketing and of ready-to-use single-units as well as the problem of aseptic compounding. Our aim was to assess a new automated primary packaging system which should ensure a higher level of sterility, thanks to its closed, sterile, ready-to-use polymer vial called "Crystal® vial". The chemical stability of a 10 mg/mL cefuroxime solution was compared in 1 mL Crystal® vials and 1 mL Luer-lock polypropylene syringes (actual reference) to eliminate any potential and specific interactions with its cyclic olefin copolymer (COC) body and elastomer stopper. Cefuroxime solution was introduced into vials and syringes and stored at -20 °C, +5 °C and +25°C/60% Relative Humidity. Cefuroxime concentration and the relative amount of the main degradation product (descarbamoyl-cefuroxime) were both determined by an HPLC/UV method indicating stability. Solutions were considered steady if the concentration remained at over 90% of the initial value. In the adapted storage conditions, the evolution of osmolality, pH and sterility was assessed. Stability profiles were identical between vials and syringes in all storage and temperature conditions. The solution was stable (cefuroxime concentration, pH and osmolality) and still sterile for 365 days at -20°C. The concentration fell below 90% after 21 days at +5 °C and after 16 h at +25°C/60%s relative humidity. The COC and thermoplastic elastomer of the vials had no impact on the degradation process confirming its possible use for a ready-to-use cefuroxime solution single-unit dose.

Ionic solubility and solutal advection governed augmented evaporation kinetics of salt solution pendant droplets

NASA Astrophysics Data System (ADS)

Jaiswal, Vivek; Harikrishnan, A. R.; Khurana, Gargi; Dhar, Purbarun

2018-01-01

The presence of dispersed inclusions is known to modify the interfacial characteristics in liquids by adsorption-desorption of the ions at interfaces. The present article reports the influencing role of dissolved ions in a polar fluid on its evaporation dynamics. The evaporation dynamics of pendant droplets of aqueous solutions of variant simple salts and concentrations have been experimentally studied. The presence of salts is observed to enhance the evaporation rate (obeying the classical D2 law), and the enhancement has been found to hold a direct proportionality to the concentration of the dissolved salt. Furthermore, it is observed that the degree of enhancement in the evaporation rate is also directly proportional to the solubility of the salt in question. The phenomenon is explained based on the chemical kinetics and thermodynamics of hydration of the ionic species in the polar fluid. The classical evaporation rate constant formulation is found to be inadequate in modeling the enhanced species transport. Additional probing via particle image velocimetry reveals augmented internal circulation within the evaporating salt based drops compared to pure water. Mapping the dynamic surface tension reveals that a salt concentration gradient is generated between the bulk and periphery of the droplet and it could be responsible for the internal advection cells visualized. A thermo-solutal Marangoni and Rayleigh convection based mathematical formulation has been put forward, and it is shown that the enhanced solute-thermal convection could play a major role in enhanced evaporation. The internal circulation mapped from experiments is found to be in good quantitative agreement with the model predictions. Scaling analysis further reveals that the stability of the solutal Marangoni convection surpasses the thermal counterpart with higher salt concentration and solubility. The present article sheds insight into the possible domineering role of conjugate thermohydraulic and mass transport phenomena on the evaporation kinetics aqueous droplets with ionic inclusions.

Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH and Selected Flavors in e-Cigarette Cartridges and Refill Solutions

PubMed Central

Lisko, Joseph G.; Tran, Hang; Stanfill, Stephen B.; Blount, Benjamin C.; Watson, Clifford H.

2015-01-01

Introduction Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH and flavors in 36 e-liquids brands from four manufacturers. Methods We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control (QC) validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH and flavors. Results Three-quarters of the products contained lower measured nicotine levels than the stated label values (6% - 42% by concentration). The pH for e-liquids ranged from 5.1 – 9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids. Conclusions Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. Pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products. PMID:25636907

Intraocular concentrations of gatifloxacin and moxifloxacin in the anterior chamber via diffusion through the cornea using collagen shields.

PubMed

Kleinmann, Guy; Larson, Scott; Neuhann, Irmingard M; Hunold, Anne C; LeBoyer, Russell; Hickman, Scott; Mamalis, Nick; Olson, Randall J

2006-02-01

To evaluate the penetration of gatifloxacin and moxifloxacin into the anterior chamber, and any adverse reaction to the cornea, using collagen shields presoaked in oversaturated solutions of the antibiotics. Collagen shields, presoaked for 10 minutes in an oversaturated solution of gatifloxacin or moxifloxacin, were placed on the surface of each of the corneas of 15 rabbits for a total of 30 eyes (15 in each group). The antibiotics were prepared by dissolving the powder form of the antibiotics in a solution until no further particulate could be further dissolved. Aqueous humor samples were taken 3.5 and 6 hours later. The initial concentrations of gatifloxacin and moxifloxacin were 5.43 +/- 0.16 mg/mL and 3.14 +/- 0.22 mg/mL, respectively. The average concentration of gatifloxacin in the anterior chamber was higher than that of moxifloxacin at the 3.5-hour sample (6.32 +/- 2.67 microg/mL versus 3.55 +/- 3.5 microg/mL, P = 0.0034). The concentrations of both antibiotics, although decreased, remained relatively high at the 6-hour sample (1.39 +/- 1.13 microg/mL versus 0.816 +/- 0.6 microg/mL at 6 hours, respectively, P = 0.22). No obvious clinical or histologic signs of toxicity were noticed in either group. Gatifloxacin and moxifloxacin showed good penetration into the anterior chamber with no obvious adverse reaction to the cornea. The concentrations in the anterior chamber exceeded the minimal inhibitory concentration (MIC) 90 of most organisms responsible for postoperative endophthalmitis (POE).

By-products formation during degradation of isoproturon in aqueous solution. II: Chlorination.

PubMed

Mascolo, G; Lopez, A; James, H; Fielding, M

2001-05-01

After a previous study in which the considered oxidant was ozone (Part I), a laboratory investigation has been carried out to study the degradation of the herbicide isoproturon during its reaction with another oxidant, i.e. chlorine, in aqueous solution (Part II; this paper). The specific aim was to identify the by-products formed. The effects of pH and the presence of bromide ions were studied. Reactions have been carried out at room temperature, in phosphate buffered aqueous solutions, at four pHs (6, 7, 8 and 9). By-products identification was first performed using relatively high initial reagent concentrations which were analytically convenient ([isoproturon] = 40 mg/l, [HClO + ClO-] = 160 mg Cl/l, [Br-] = 80 mg/l). In follow-up studies, the by-products identified during this preliminary step were searched for when using concentration values closer to those actually encountered at real water treatment plants ([isoproturon] = 0.4 and 0.004 mg/l, [HClO + ClO-] = 1.6 mg Cl/l, [Br-] = 0.8 and 0.008 mg/l). Under all of the studied conditions, the results showed that isoproturon is completely degraded and that it decays much faster in the presence of bromide. The pH has a negligible influence when bromide ions are absent. On the contrary, if bromide ions are present, the isoproturon decay is slower at higher pH values. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses have led to the identification of several by-products as a result of simultaneous oxidation and substitution reactions, both occurring on the aromatic ring of the herbicide. However, the more abundant by-products are those resulting from the oxidation of the isoproturon aromatic ring. As far as halogenated by-products are concerned, the higher the bromide ion concentration the higher the ratio of brominated to chlorinated by-products. On the basis of the analytical results, a pathway for isoproturon degradation under the studied conditions is proposed.

Process for production of solution-derived (Pb,La)(Nb,Sn,Zr,Ti)O{sub 3} thin films and powders

DOEpatents

Boyle, T.J.

1999-01-12

A simple and rapid process for synthesizing (Pb,La)(Nb,Sn,Zr,Ti)O{sub 3} precursor solutions and subsequent ferroelectric thin films and powders of the perovskite phase of these materials has been developed. This process offers advantages over standard methods, including: rapid solution synthesis (<10 minutes), use of commercially available materials, film production under ambient conditions, ease of lanthanum dissolution at high concentrations, and no heating requirements during solution synthesis. For lanthanum-doped ferroelectric materials, the lanthanum source can be added with total synthesis time less than 10 minutes. Films and powders are crystallized at approximately 650 C and exhibit ferroelectric properties comparable to films and powders produced by other techniques which require higher crystallization temperatures. 2 figs.

Process for production of solution-derived (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 thin films and powders

DOEpatents

Boyle, Timothy J.

1999-01-01

A simple and rapid process for synthesizing (Pb,La)(Nb,Sn,Zr,Ti)O.sub.3 precursor solutions and subsequent ferroelectric thin films and powders of the perovskite phase of these materials has been developed. This process offers advantages over standard methods, including: rapid solution synthesis (<10 minutes), use of commercially available materials, film production under ambient conditions, ease of lanthanum dissolution at high concentrations, and no heating requirements during solution synthesis. For lanthanum-doped ferroelectric materials, the lanthanum source can be added with total synthesis time less than 10 minutes. Films and powders are crystallized at approximately 650.degree. C. and exhibit ferroelectric properties comparable to films and powders produced by other techniques which require higher crystallization temperatures.

Magnetic separation of Dy(III) ions from homogeneous aqueous solutions

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

Pulko, B., E-mail: Barbara.Pulko@tu-dresden.de; Yang, X.; Lei, Z.

2014-12-08

The possibility to enrich paramagnetic dysprosium(III) ions in a magnetic field gradient is proved by means of interferometry, which may open the route for a magnetic separation of rare earth ions from aqueous solutions. The separation dynamics are studied for three different concentrations of DyCl{sub 3} and compared with those found recently in a sulphate solution of the 3d ion Mn(II). In view of the similar-sized hydration spheres for Dy(III) and Mn(II), the slower separation dynamics in DyCl{sub 3} is attributed to both a higher densification coefficient and the strong impact of Brownian motion due to the absence of ion-pairmore » clusters.« less

Long-term effects of rainforest disturbance on the nutrient composition of throughfall, organic layer percolate and soil solution at Mt. Kilimanjaro.

PubMed

Schrumpf, Marion; Axmacher, Jan C; Zech, Wolfgang; Lehmann, Johannes; Lyaruu, Herbert V C

2007-04-15

At the lower parts of the forest belt at Mt. Kilimanjaro, selective logging has led to a mosaic of mature forest, old secondary forests ( approximately 60 years), and old clearings ( approximately 10 years) covered by shrub vegetation. These variations in the vegetation are reflected by differences in nutrient leaching from the canopy and in both amount and quality of litter reaching the ground, thereby also influencing mineralization rates and the composition of seepage water in litter percolate and soil solution. The aim of this study was to investigate how above- and belowground nutrient dynamics vary between regeneration stages, and if forest regeneration at the clearings is hampered by a deterioration of abiotic site conditions. K, Mg, Ca, Na and N compounds were analysed in rainfall, throughfall, organic layer percolate and the soil solution to a depth of 1.00 m at three clearings, three secondary forest and four mature forest sites. Element fluxes via throughfall showed only small variations among regeneration stages except for K and NO(3)-N. With 57-83 kg ha(-1) a(-1)and 2.6-4.1 kg ha(-1) a(-1) respectively, K and NO(3)-N fluxes via throughfall were significantly higher at the clearings than at the mature forest sites (32-37 and 0.7-1.0 kg ha(-1) a(-1) for K and NO(3)-N). In organic layer percolate and in soil solution at 0.15-m soil depth, concentrations of K, Mg, Ca and N were highest at the clearings. In the organic layer percolate, median K concentrations were e.g. 7.4 mg l(-1) for the clearings but only 1.4 mg l(-1) for the mature forests, and for NO(3)-N, median concentrations were 3.1 mg l(-1) for the clearings but only 0.92 mg l(-1) for the mature forest sites. Still, differences in annual means between clearings and mature forests were not always significant due to a high variability within the clearings. With the exception of NO(3)-N, belowground nutrient concentrations in secondary forests ranged between concentrations in mature forests and clearings. Vegetation type-specific differences decreased with increasing soil depths in the soil solution. Overall, the opening of the forest led to a higher spatial and seasonal variation of nutrient concentrations in the seepage water. These results suggest differences in both mineralization rates and in nutrient budgeting at different regeneration stages. Since nutrient availability was highest at the clearings and no compaction of the soil was observed, deterioration of soil properties did not seem to be the main reason for the impeded regeneration on the clearings.

Evaluation of an oral electrolyte solution for treatment of mild to moderate dehydration in dogs with hemorrhagic diarrhea.

PubMed

Reineke, Erica L; Walton, Karie; Otto, Cynthia M

2013-09-15

To determine the safety and efficacy of an electrolyte solution for oral administration (OES) for the correction of mild to moderate dehydration associated with hemorrhagic diarrhea in dogs. Nonrandomized, noncontrolled clinical trial. 20 dogs that had hemorrhagic diarrhea with < 3 episodes of vomiting. All dogs underwent testing for parvovirus infection, were given maropitant citrate to control emesis, and were offered an OES. Intravenous crystalloid fluid administration was performed when dogs refused the OES or had vomiting, a 5% increase in PCV, 5% decrease in body weight, serum creatinine or BUN concentration higher than at admission, or clinically important alterations in blood electrolyte or serum glucose concentrations. 13 (65%) dogs voluntarily consumed the OES; 7 (35%) dogs refused the OES and received a balanced electrolyte solution IV instead. All 13 dogs in the OES group consumed the solution ≤ 5 hours after hospital admission. Eight and 16 hours after admission, PCV and serum total protein and BUN concentrations were significantly lower than at hospital admission in the OES group, whereas no significant changes were identified in venous blood pH, base excess, and concentrations of sodium, potassium, chloride, ionized calcium, ionized magnesium, and lactate. The cost of treatment was significantly less for the OES group than for the IV treated group. Rehydration therapy with an OES was effective and safe in dogs with mild to moderate dehydration associated with hemorrhagic diarrhea. Potential benefits of this treatment approach for gastroenteritis in dogs, compared with traditional IV fluid administration, include lower owner-related veterinary costs and decreased staff time associated with treatment.

Stabilizing sodium hypochlorite at high pH: effects on soft tissue and dentin.

PubMed

Jungbluth, Holger; Marending, Monika; De-Deus, Gustavo; Sener, Beatrice; Zehnder, Matthias

2011-05-01

When sodium hypochlorite solutions react with tissue, their pH drops and tissue sorption decreases. We studied whether stabilizing a NaOCl solution at a high pH would increase its soft-tissue dissolution capacity and effects on the dentin matrix compared with a standard NaOCl solution of the same concentration and similar initial pH. NaOCl solutions were prepared by mixing (1:1) a 10% stock solution with water (standard) or 2 mol/L NaOH (stabilized). Physiological saline and 1 mol/L NaOH served as the controls. Chlorine content and alkaline capacity of NaOCl solutions were determined. Standardized porcine palatal soft-tissue specimens and human root dentin bars were exposed to test and control solutions. Weight loss percentage was assessed in the soft-tissue dissolution assay. Three-point bending tests were performed on the root dentin bars to determine the modulus of elasticity and flexural strength. Values between groups were compared using one-way analysis of variance with the Bonferroni correction for multiple testing (α < .05). Both solutions contained 5% NaOCl. One milliliter of the standard and the stabilized solution consumed 4.0 mL and 13.7 mL of a 0.1-mol/L HCl solution before they reached a pH level of 7.5, respectively. The stabilized NaOCl dissolved significantly more soft tissue than the standard solution, and the pH remained high. It also caused a higher loss in elastic modulus and flexure strength (P < .05) than the control solutions, whereas the standard solution did not. NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

SULFATE-SULFUR METABOLISM IN THE RAT FETUS AS INDICATED BY SULFUR-35

PubMed Central

Dziewiatkowski, Dominic D.

1953-01-01

Twenty-four hours after the intraperitoneal injection of sodium sulfate-S35 into pregnant rats, sulfur-35 was found in the embryos. The amount of the sulfur-35 retained by the embryos was directly related to their degree of development in utero. A large fraction of the sulfur-35 found in the embryos was insoluble in 5 per cent trichloroacetic acid. At the 9th to 10th day of development, about 40 per cent of the sulfur-35 was present in this fraction. In 20-day-old embryos this fraction accounted for nearly 90 per cent of the total. Radioautographs of sections of embryos fixed in a solution of formaldehyde revealed that the sulfur-35 was most highly concentrated in the cartilaginous portion of the skeleton. All other tissues gave much weaker autographic reactions, comparable with the over-all reaction obtained when sections from embryos fixed in a solution of formaldehyde saturated with barium hydroxide were used. By analysis for the sulfur-35 content of individual tissues the concentration of the sulfur-35 in humeri from 20-day-old embryos was found to be about 30 times that in the maternal sternum. The concentration of the isotope in the skeletal muscle, brain, heart, and skin of the same embryos was also higher than in the corresponding maternal tissues. On the other hand, the concentration of the sulfur-35 in the maternal gastrointestinal tract plus contents was higher than in the gastrointestinal tract and contents of the embryos. PMID:13069655

Biotherapeutic formulation factors affecting metal leachables from stainless steel studied by design of experiments.

PubMed

Zhou, Shuxia; Evans, Brad; Schöneich, Christian; Singh, Satish K

2012-03-01

Trace amounts of metals are inevitably present in biotherapeutic products. They can arise from various sources. The impact of common formulation factors such as protein concentration, antioxidant, metal chelator concentration and type, surfactant, pH, and contact time with stainless steel on metal leachables was investigated by a design of experiments approach. Three major metal leachables, iron, chromium, and nickel were monitored by inductively coupled plasma-mass spectrometry. It was observed that among all the tested factors, contact time, metal chelator concentration, and protein concentration were statistically significant factors with higher temperature resulting in higher levels of leached metals. Within a pH range of 5.5-6.5, solution pH played a minor role for chromium leaching at 25°C. No statistically significant difference was observed due to type of chelator, presence of antioxidant, or surfactant. In order to optimize a biotherapeutic formulation to achieve a target drug product shelf life with acceptable quality, each formulation component must be evaluated for its impact.

Differences in Steady-State Net Ammonium and Nitrate Influx by Cold- and Warm-Adapted Barley Varieties 1

PubMed Central

Bloom, Arnold J.; Chapin, F. Stuart

1981-01-01

A flowing nutrient culture system permitted relatively rapid determination of the steady-state net nitrogen influx by an intact barley (Hardeum vulgare L. cv Kombar and Olli) plant. Ion-selective electrodes monitored the depletion of ammonium and nitrate from a nutrient solution after a single pass through a root cuvette. Influx at concentrations as low as 4 micromolar was measured. Standard errors for a sample size of three plants were typically less than 10% of the mean. When grown under identical conditions, a variety of barley bred for cold soils had higher nitrogen influx rates at low concentrations and low temperatures than one bred for warm soils, whereas the one bred for warm soils had higher influx rates at high concentrations and high temperatures. Ammonium was more readily absorbed than nitrate by both varieties at all concentrations and temperatures tested. Ammonium and nitrate influx in both varieties were equally inhibited by low temperatures. PMID:16662052

Investigation of the column performance of cadmium(II) biosorption by Cladophora crispata flocs in a packed bed

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

Aksu, Z.; Kutsal, T.; Caglar, A.

1998-03-01

In this study the biosorption of cadmium(II) ions to dried flocs of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The cadmium(II) removal performance of the column was investigated as a function of the cadmium(II)-bearing solution flow rate and the inlet cadmium(II) concentration. Removal and total removal percentages of cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet cadmium(II) concentration on the column capacity was also investigated. Data confirmed thatmore » early saturation and lower cadmium(II) removals were observed at higher flow rates and at higher cadmium(II) concentrations. Column experiments also showed that maximum specific cadmium(II) uptake values of C. crispata flocs were as high as those of other biomass sorbents.« less

Nontoxic concentration of ceftazidime and flomoxef sodium for intravitreal use--evaluated by in-vitro ERG.

PubMed

Tanabe, J; Kitano, K; Suzuki, T; Okayama, Y; Mochizuki, K; Kawasaki, K

1990-01-01

The effects of ceftazidime (CAZ) and flomoxef sodium (FMOX) on the in-vitro electroretinogram (ERG) of albino rabbits were studied. The a-wave, the b-wave and the oscillatory potential (OP) were unchanged by 0.3mM (0.19mg/ml) CAZ-containing solution. The OP was suppressed by 0.5mM (0.32mg/ml) CAZ. The a-wave, the b-wave and the OP were unchanged by 0.5mM (0.26mg/ml) FMOX. The OP was suppressed and its peak latency was delayed by 2mM (0.52mg/ml) FMOX. The concentration of 0.3mM (0.19mg/ml) CAZ was higher than its minimum inhibitory concentration (MIC) against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Serratia marcescens and Propionibacterium acnes. The concentration of 0.5mM (0.26mg/ml) FMOX was higher than its MIC against Staphylococcus aureus, Staphylococcus epidermidis, Serratia marcescens and Propionibacterium acnes.

Spectroscopic properties of triangular silver nanoplates immobilized on polyelectrolyte multilayer-modified glass substrates

NASA Astrophysics Data System (ADS)

Rabor, Janice B.; Kawamura, Koki; Muko, Daiki; Kurawaki, Junichi; Niidome, Yasuro

2017-07-01

Fabrication of surface-immobilized silver nanostructures with reproducible plasmonic properties by dip-coating technique is difficult due to shape alteration. To address this challenge, we used a polyelectrolyte multilayer to promote immobilization of as-received triangular silver nanoplates (TSNP) on a glass substrate through electrostatic interaction. The substrate-immobilized TSNP were characterized by absorption spectrophotometry and scanning electron microscopy. The bandwidth and peak position of localized surface plasmon resonance (LSPR) bands can be tuned by simply varying the concentration of the colloidal solution and immersion time. TSNP immobilized from a higher concentration of colloidal solution with longer immersion time produced broadened LSPR bands in the near-IR region, while a lower concentration with shorter immersion time produced narrower bands in the visible region. The shape of the nanoplates was retained even at long immersion time. Analysis of peak positions and bandwidths also revealed the point at which the main species of the immobilization had been changed from isolates to aggregates.

Structure and Dynamics of Highly PEG-ylated Sterically Stabilized Micelles in Aqueous Media

PubMed Central

Vuković, Lela; Khatib, Fatima A.; Drake, Stephanie P.; Madriaga, Antonett; Brandenburg, Kenneth S.; Král, Petr; Onyuksel, Hayat

2011-01-01

Molecular assemblies of highly PEG-ylated phospholipids are important in many biomedical applications. We study sterically stabilized micelles (SSM) of self-assembled DSPE-PEG2000 in pure water and isotonic HEPES buffered saline solution. The observed SSM sizes of 2 – 15 nm largely depend on the solvent and the lipid concentration used. The critical micelle concentration (CMC) of DSPE-PEG2000 is ≈ 10 times higher in water than in buffer and the viscosity of the dispersion dramatically increases with the lipid concentration. To explain the experimentally observed results, we perform atomistic molecular dynamics simulations of the solvated SSM. Our modeling reveal that the observed assemblies have very different aggregation numbers of Nagg ≈ 90 (saline solution) and Nagg < 8 (water), due to very different screening of their charged −PO4− groups. We also demonstrate that the micelle cores can inflate and their corona highly fluctuate, allowing thus storage and delivery of molecules with different chemistry. PMID:21780810

Structure and dynamics of highly PEG-ylated sterically stabilized micelles in aqueous media.

PubMed

Vuković, Lela; Khatib, Fatima A; Drake, Stephanie P; Madriaga, Antonett; Brandenburg, Kenneth S; Král, Petr; Onyuksel, Hayat

2011-08-31

Molecular assemblies of highly PEG-ylated phospholipids are important in many biomedical applications. We have studied sterically stabilized micelles (SSMs) of self-assembled DSPE–PEG2000 in pure water and isotonic HEPES-buffered saline solution. The observed SSM sizes of 2–15 nm largely depend on the solvent and the lipid concentration used. The critical micelle concentration of DSPE–PEG2000 is 10 times higher in water than in buffer, and the viscosity of the dispersion dramatically increases with the lipid concentration. To explain the experimentally observed results, we performed atomistic molecular dynamics simulations of solvated SSMs. Our modeling revealed that the observed assemblies have very different aggregation numbers (N(agg) ≈ 90 in saline solution and N(agg) < 8 in water) because of very different screening of their charged PO4(–) groups. We also demonstrate that the micelle cores can inflate and their coronas can fluctuate strongly, thus allowing storage and delivery of molecules with different chemistries.

Hydroquinone; A Novel Bioactive Compound from Plant-Derived Smoke Can Cue Seed Germination of Lettuce.

PubMed

Kamran, Muhammad; Khan, Abdul L; Ali, Liaqat; Hussain, Javid; Waqas, Muhammad; Al-Harrasi, Ahmed; Imran, Qari M; Kim, Yoon-Ha; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

2017-01-01

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus , Aloe vera , Ginkgo biloba , and Cymbopogon jwarancusa . Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n -hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1 . This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Hydroquinone; A novel bioactive compound from plant-derived smoke can cue seed germination of lettuce

NASA Astrophysics Data System (ADS)

Kamran, Muhammad; Khan, Abdul L.; Ali, Liaqat; Hussain, Javid; Waqas, Muhammad; Al-Harrasi, Ahmed; Imran, Qari M.; Kim, Yoon-Ha; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

2017-05-01

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus, Aloe vera, Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from Ginkgo biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10 and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

Operando Solid-State NMR Observation of Solvent-Mediated Adsorption-Reaction of Carbohydrates in Zeolites

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

Qi, Long; Alamillo, Ricardo; Elliott, William A.

Liquid-phase processing of molecules using heterogeneous catalysts – an important strategy for obtaining renewable chemicals sustainably from biomass – involves reactions that occur at solid-liquid interfaces. In glucose isomerization catalyzed by basic faujasite zeolites, the catalytic activity depends strongly on the solvent composition: initially, it declines precipitously when water is mixed with a small amount of the organic co-solvent γ-valerolactone (GVL), then recovers as the GVL content increases. Using solid-state 13C NMR spectroscopy, we observed glucose isomers located inside the zeolite pores directly, and followed their transformations into fructose and mannose in real time. At low GVL concentrations, glucose ismore » depleted in the zeolite pores relative to the liquid phase, while higher GVL concentrations in solution drive glucose inside the pores, resulting in up to a 32 enhancement in the local glucose concentration. Although their populations exchange rapidly, molecules present at the reactive interface experience a significantly different environment from the bulk solution.« less

Hydroquinone; A Novel Bioactive Compound from Plant-Derived Smoke Can Cue Seed Germination of Lettuce

PubMed Central

Kamran, Muhammad; Khan, Abdul L.; Ali, Liaqat; Hussain, Javid; Waqas, Muhammad; Al-Harrasi, Ahmed; Imran, Qari M.; Kim, Yoon-Ha; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

2017-01-01

Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control. PMID:28553632