water based solution: Topics by Science.gov

Sample records for water based solution

Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions

NASA Astrophysics Data System (ADS)

Wutich, A.; White, A. C.; Roberts, C. M.; White, D. D.; Larson, K. L.; Brewis, A.

2013-06-01

In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences based on development status and, to a lesser extent, water scarcity. People in less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in more developed sites. Thematically, people in less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community based solutions, while people in more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in water-rich sites. Thematically, people in water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.
Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions

NASA Astrophysics Data System (ADS)

Wutich, A.; White, A. C.; White, D. D.; Larson, K. L.; Brewis, A.; Roberts, C.

2014-01-01

In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences associated with development status and, to a lesser extent, water scarcity. People in the two less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in the more developed sites. Thematically, people in the two less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community-based solutions, while people in the more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in the two water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in the water-rich sites. Thematically, people in the two water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in the water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.
Evaluation of strategies for nature-based solutions to drought: a decision support model at the national scale

NASA Astrophysics Data System (ADS)

Simpson, Mike; Ives, Matthew; Hall, Jim

2016-04-01

There is an increasing body of evidence in support of the use of nature based solutions as a strategy to mitigate drought. Restored or constructed wetlands, grasslands and in some cases forests have been used with success in numerous case studies. Such solutions remain underused in the UK, where they are not considered as part of long-term plans for supply by water companies. An important step is the translation of knowledge on the benefits of nature based solutions at the upland/catchment scale into a model of the impact of these solutions on national water resource planning in terms of financial costs, carbon benefits and robustness to drought. Our project, 'A National Scale Model of Green Infrastructure for Water Resources', addresses this issue through development of a model that can show the costs and benefits associated with a broad roll-out of nature based solutions for water supply. We have developed generalised models of both the hydrological effects of various classes and implementations of nature-based approaches and their economic impacts in terms of construction costs, running costs, time to maturity, land use and carbon benefits. Our next step will be to compare this work with our recent evaluation of conventional water infrastructure, allowing a case to be made in financial terms and in terms of security of water supply. By demonstrating the benefits of nature based solutions under multiple possible climate and population scenarios we aim to demonstrate the potential value of using nature based solutions as a component of future long-term water resource plans. Strategies for decision making regarding the selection of nature based and conventional approaches, developed through discussion with government and industry, will be applied to the final model. Our focus is on keeping our work relevant to the requirements of decision-makers involved in conventional water planning. We propose to present the outcomes of our model for the evaluation of nature-based solutions at catchment scale and ongoing results of our national-scale model.
Preparation and evaluation of HPMC-based pirfenidone solution in vivo.

PubMed

Yang, Mei; Yang, Yang-Fan; Lei, Ming; Ye, Cheng-Tian; Zhao, Chun-Shun; Xu, Jian-Gang; Wu, Kai-Li; Yu, Min-Bin

2017-01-01

Pirfenidone (PFD) has exhibited therapeutic potential in the treatment of cell proliferative disorders. The previously developed 0.5% water-based PFD eye drops by our team exhibited antiscarring effectiveness and ocular safety but with a limit of short half-life and poor bioavailability. To increase bioavailability of the water-based PFD eye drops, we prepared a viscous solution by adding hydroxypropyl methylcellulose (HPMC, F4M), which acted as a viscosity-enhancer. Subsequently, we compared the HPMC-based PFD solution with the water-based PFD eye drops. PFD solution with 1% HPMC (w/v) was prepared, and the viscosities at different shear rates were measured to investigate its rheology. PFD concentrations in the tear, aqueous humor, conjunctiva, cornea, and sclerae of New Zealand rabbits were detected at different time points with high-performance liquid chromatography (HPLC) following single instillation of the 0.5% PFD (w/v) water-based eye drops or HPMC-based solution. Compared with the 0.5% water-based PFD eye drops, the HPMC-based solution increased the PFD levels in tears and prolonged the residence time from 10 to more than 20 min (p < .01). Consequently, the concentrations of PFD in aqueous humor, conjunctiva, cornea, and sclera were elevated to varying degrees until 90 min after topical administration. The developed formulation possesses a same readily administration and simple preparation as the PFD eye drops; however, the HPMC-based solution exhibited the higher bioavailability.
AST/R–BASED WATER REUSE AS A PART OF THE TOTAL WATER SOLUTION FOR WATER-STRESSED REGIONS: AN OVERVIEW OF ENGINEERING PRACTICE AND REGULATORY PROSPECTIVE

EPA Science Inventory

Water supply and demand are increasingly unbalanced in many parts of the world. To address the imbalance, the total water solution methodology simultaneously considers regulatory, engineering, environmental and economic factors to optimize risk management solutions for an entire...
AST/R BASED WATER REUSE AS A PART OF THE TOTAL WATER SOLUTION FOR WATER-STRESSED REGIONS: AN OVERVIEW OF ENGINEERING PRACTICE AND REGULATORY PROSPECTIVE

EPA Science Inventory

Water supply and demand are increasingly unbalanced in many parts of the world. To address the imbalance, the total water solution methodology simultaneously considers regulatory, engineering, environmental and economic factors to optimize risk management solutions for an entire ...
Export of nutrients and major ionic solutes from a rain forest catchment in the Central Amazon Basin

NASA Astrophysics Data System (ADS)

Lesack, Lance F. W.

1993-03-01

The relative roles of base flow runoff versus storm flow runoff versus subsurface outflow in controlling total export of solutes from a 23.4-ha catchment of undisturbed rain forest in the central Amazon Basin were evaluated from water and solute flux measurements performed over a 1 year period. Solutes exported via 173 storms during the study were estimated from stream water samples collected during base flow conditions and during eight storms, and by utilizing a hydrograph separation technique in combination with a mixing model to partition storm flow from base flow fluxes. Solutes exported by subsurface outflow were estimated from groundwater samples from three nests of piezometers installed into the streambed, and concurrent measurements of hydraulic conductivity and hydraulic head gradients. Base flow discharge represented 92% of water outflow from the basin and was the dominant pathway of solute export. Although storm flow discharge represented only 5% of total water outflow, storm flow solute fluxes represented up to 25% of the total annual export flux, though for many solutes the portion was less. Subsurface outflow represented only 2.5% of total water outflow, and subsurface solute fluxes never represented more than 5% of the total annual export flux. Measurement errors were relatively high for storm flow and subsurface outflow fluxes, but cumulative measurement errors associated with the total solute fluxes exported from the catchment, in most cases, ranged from only ±7% to 14% because base flow fluxes were measured relatively well. The export fluxes of most solutes are substantially less than previously reported for comparable small catchments in the Amazon basin, and these differences cannot be reconciled by the fact that storm flow and subsurface outflows were not appropriately measured in previous studies.
Polymer optical fiber grating as water activity sensor

NASA Astrophysics Data System (ADS)

Zhang, Wei; Webb, David J.

2014-05-01

Controlling the water content within a product has long been required in the chemical processing, agriculture, food storage, paper manufacturing, semiconductor, pharmaceutical and fuel industries. The limitations of water content measurement as an indicator of safety and quality are attributed to differences in the strength with which water associates with other components in the product. Water activity indicates how tightly water is "bound," structurally or chemically, in products. Water absorption introduces changes in the volume and refractive index of poly(methyl methacrylate) PMMA. Therefore for a grating made in PMMA based optical fiber, its wavelength is an indicator of water absorption and PMMA thus can be used as a water activity sensor. In this work we have investigated the performance of a PMMA based optical fiber grating as a water activity sensor in sugar solution, saline solution and Jet A-1 aviation fuel. Samples of sugar solution with sugar concentration from 0 to 8%, saline solution with concentration from 0 to 22%, and dried (10ppm), ambient (39ppm) and wet (68ppm) aviation fuels were used in experiments. The corresponding water activities are measured as 1.0 to 0.99 for sugar solution, 1.0 to 0.86 for saline solution, and 0.15, 0.57 and 1.0 for the aviation fuel samples. The water content in the measured samples ranges from 100% (pure water) to 10 ppm (dried aviation fuel). The PMMA based optical fiber grating exhibits good sensitivity and consistent response, and Bragg wavelength shifts as large as 3.4 nm when the sensor is transferred from dry fuel to wet fuel.
Selective aqueous extraction of organics coupled with trapping by membrane separation

DOEpatents

van Eikeren, Paul; Brose, Daniel J.; Ray, Roderick J.

1991-01-01

An improvement to processes for the selective extractation of organic solutes from organic solvents by water-based extractants is disclosed, the improvement comprising coupling various membrane separation processes with the organic extraction process, the membrane separation process being utilized to continuously recycle the water-based extractant and at the same time selectively remove or concentrate organic solute from the water-based extractant.
The SOLUTIONS project: challenges and responses for present and future emerging pollutants in land and water resources management.

PubMed

Brack, Werner; Altenburger, Rolf; Schüürmann, Gerrit; Krauss, Martin; López Herráez, David; van Gils, Jos; Slobodnik, Jaroslav; Munthe, John; Gawlik, Bernd Manfred; van Wezel, Annemarie; Schriks, Merijn; Hollender, Juliane; Tollefsen, Knut Erik; Mekenyan, Ovanes; Dimitrov, Saby; Bunke, Dirk; Cousins, Ian; Posthuma, Leo; van den Brink, Paul J; López de Alda, Miren; Barceló, Damià; Faust, Michael; Kortenkamp, Andreas; Scrimshaw, Mark; Ignatova, Svetlana; Engelen, Guy; Massmann, Gudrun; Lemkine, Gregory; Teodorovic, Ivana; Walz, Karl-Heinz; Dulio, Valeria; Jonker, Michiel T O; Jäger, Felix; Chipman, Kevin; Falciani, Francesco; Liska, Igor; Rooke, David; Zhang, Xiaowei; Hollert, Henner; Vrana, Branislav; Hilscherova, Klara; Kramer, Kees; Neumann, Steffen; Hammerbacher, Ruth; Backhaus, Thomas; Mack, Juliane; Segner, Helmut; Escher, Beate; de Aragão Umbuzeiro, Gisela

2015-01-15

SOLUTIONS (2013 to 2018) is a European Union Seventh Framework Programme Project (EU-FP7). The project aims to deliver a conceptual framework to support the evidence-based development of environmental policies with regard to water quality. SOLUTIONS will develop the tools for the identification, prioritisation and assessment of those water contaminants that may pose a risk to ecosystems and human health. To this end, a new generation of chemical and effect-based monitoring tools is developed and integrated with a full set of exposure, effect and risk assessment models. SOLUTIONS attempts to address legacy, present and future contamination by integrating monitoring and modelling based approaches with scenarios on future developments in society, economy and technology and thus in contamination. The project follows a solutions-oriented approach by addressing major problems of water and chemicals management and by assessing abatement options. SOLUTIONS takes advantage of the access to the infrastructure necessary to investigate the large basins of the Danube and Rhine as well as relevant Mediterranean basins as case studies, and puts major efforts on stakeholder dialogue and support. Particularly, the EU Water Framework Directive (WFD) Common Implementation Strategy (CIS) working groups, International River Commissions, and water works associations are directly supported with consistent guidance for the early detection, identification, prioritisation, and abatement of chemicals in the water cycle. SOLUTIONS will give a specific emphasis on concepts and tools for the impact and risk assessment of complex mixtures of emerging pollutants, their metabolites and transformation products. Analytical and effect-based screening tools will be applied together with ecological assessment tools for the identification of toxicants and their impacts. The SOLUTIONS approach is expected to provide transparent and evidence-based candidates or River Basin Specific Pollutants in the case study basins and to assist future review of priority pollutants under the WFD as well as potential abatement options. Copyright © 2014 Elsevier B.V. All rights reserved.
Non-Invasive Acoustic-Based Monitoring of Heavy Water and Uranium Process Solutions

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

Pantea, Cristian; Sinha, Dipen N.; Lakis, Rollin Evan

This presentation includes slides on Project Goals; Heavy Water Production Monitoring: A New Challenge for the IAEA; Noninvasive Measurements in SFAI Cell; Large Scatter in Literature Values; Large Scatter in Literature Values; Highest Precision Sound Speed Data Available: New Standard in H/D; ~400 pts of data; Noninvasive Measurements in SFAI Cell; New funding from NA241 SGTech; Uranium Solution Monitoring: Inspired by IAEA Challenge in Kazakhstan; Non-Invasive Acoustic-Based Monitoring of Uranium in Solutions; Non-Invasive Acoustic-Based Monitoring of Uranium in Solutions; and finally a summary.
DOE Office of Scientific and Technical Information (OSTI.GOV)

CHUGH, Devesh; Gluesenkamp, Kyle R; Abdelaziz, Omar

In this study, development of a novel system for combined water heating, dehumidification, and space evaporative cooling is discussed. Ambient water vapor is used as a working fluid in an open system. First, water vapor is absorbed from an air stream into an absorbent solution. The latent heat of absorption is transferred into the process water that cools the absorber. The solution is then regenerated in the desorber, where it is heated by a heating fluid. The water vapor generated in the desorber is condensed and its heat of phase change is transferred to the process water in the condenser.more » The condensed water can then be used in an evaporative cooling process to cool the dehumidified air exiting the absorber, or it can be drained if primarily dehumidification is desired. Essentially, this open absorption cycle collects space heat and transfers it to process water. This technology is enabled by a membrane-based absorption/desorption process in which the absorbent is constrained by hydrophobic vapor-permeable membranes. Constraining the absorbent film has enabled fabrication of the absorber and desorber in a plate-and-frame configuration. An air stream can flow against the membrane at high speed without entraining the absorbent, which is a challenge in conventional dehumidifiers. Furthermore, the absorption and desorption rates of an absorbent constrained by a membrane are greatly enhanced. Isfahani and Moghaddam (Int. J. Heat Mass Transfer, 2013) demonstrated absorption rates of up to 0.008 kg/m2s in a membrane-based absorber and Isfahani et al. (Int. J. Multiphase Flow, 2013) have reported a desorption rate of 0.01 kg/m2s in a membrane-based desorber. The membrane-based architecture also enables economical small-scale systems, novel cycle configurations, and high efficiencies. The absorber, solution heat exchanger, and desorber are fabricated on a single metal sheet. In addition to the open arrangement and membrane-based architecture, another novel feature of the cycle is recovery of the solution heat energy exiting the desorber by process water (a process-solution heat exchanger ) rather than the absorber exiting solution (the conventional solution heat exchanger ). This approach has enabled heating the process water from an inlet temperature of 15 C to 57 C (conforming to the DOE water heater test standard) and interfacing the process water with absorbent on the opposite side of a single metal sheet encompassing the absorber, process-solution heat exchanger, and desorber. The system under development has a 3.2 kW water heating capacity and a target thermal coefficient of performance (COP) of 1.6.« less
Corrosion inhibitors for water-base slurry in multiblade sawing

NASA Technical Reports Server (NTRS)

Chen, C. P.; Odonnell, T. P.

1982-01-01

The use of a water-base slurry instead of the standard PC oil vehicle was proposed for multiblade sawing (MBS) silicon wafering technology. Potential cost savings were considerable; however, significant failures of high-carbon steel blades were observed in limited tests using a water-based slurry during silicon wafering. Failures were attributed to stress corrosion. A specially designed fatigue test of 1095 steel blades in distilled water with various corrosion inhibitor solutions was used to determine the feasibility of using corrosion inhibitors in water-base MBS wafering. Fatigue tests indicate that several corrosion inhibitors have significant potential for use in a water-base MBS operation. Blade samples tested in these specific corrosion-inhibitor solutions exhibited considerably greater lifetime than those blades tested in PC oil.
Hot and cold water as a supercritical solvent

NASA Astrophysics Data System (ADS)

Fuentevilla, Daphne Anne

This dissertation addresses the anomalous properties of water at high temperatures near the vapor-liquid critical point and at low temperatures in the supercooled liquid region. The first part of the dissertation is concerned with the concentration dependence of the critical temperature, density, and pressure of an aqueous sodium chloride solution. Because of the practical importance of an accurate knowledge of critical parameters for industrial, geochemical, and biological applications, an empirical equation for the critical locus of aqueous sodium chloride solutions was adopted in 1999 by the International Association for the Properties of Water and Steam (IAPWS) as a guideline. However, since this original Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride was developed, two new theoretical developments occurred, motivating the first part of this dissertation. Here, I present a theory-based formulation for the critical parameters of aqueous sodium chloride solutions as a proposed replacement for the empirical formulation currently in use. This formulation has been published in the International Journal of Thermophysics and recommended by the Executive Committee of IAPWS for adoption as a Revised Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride. The second part of the dissertation addresses a new concept, considering cold water as a supercritical solvent. Based on the idea of a second, liquid-liquid, critical point in supercooled water, we explore the possibility of supercooled water as a novel supercooled solvent through the thermodynamics of critical phenomena. In 2006, I published a Physical Review letter presenting a parametric scaled equation of state for supercooled-water. Further developments based on this work led to a phenomenological mean-field "two-state" model, clarifying the nature of the phase separation in a polyamorphic single-component liquid. In this dissertation, I modify this two-state model to incorporate solutes. Critical lines emanating from the pure-water critical point show how even small additions of solute may significantly affect the thermodynamic properties and phase behavior of supercooled aqueous solutions. Some solutes, such as glycerol, can prevent spontaneous crystallization, thus making liquid-liquid separation in supercooled water experimentally accessible. This work will help in resolving the question on liquid polyamorphism in supercooled water.
Water activity in liquid food systems: A molecular scale interpretation.

PubMed

Maneffa, Andrew J; Stenner, Richard; Matharu, Avtar S; Clark, James H; Matubayasi, Nobuyuki; Shimizu, Seishi

2017-12-15

Water activity has historically been and continues to be recognised as a key concept in the area of food science. Despite its ubiquitous utilisation, it still appears as though there is confusion concerning its molecular basis, even within simple, single component solutions. Here, by close examination of the well-known Norrish equation and subsequent application of a rigorous statistical theory, we are able to shed light on such an origin. Our findings highlight the importance of solute-solute interactions thus questioning traditional, empirically based "free water" and "water structure" hypotheses. Conversely, they support the theory of "solute hydration and clustering" which advocates the interplay of solute-solute and solute-water interactions but crucially, they do so in a manner which is free of any estimations and approximations. Copyright © 2017. Published by Elsevier Ltd.
Analytical Solution for Optimum Design of Furrow Irrigation Systems

NASA Astrophysics Data System (ADS)

Kiwan, M. E.

1996-05-01

An analytical solution for the optimum design of furrow irrigation systems is derived. The non-linear calculus optimization method is used to formulate a general form for designing the optimum system elements under circumstances of maximizing the water application efficiency of the system during irrigation. Different system bases and constraints are considered in the solution. A full irrigation water depth is considered to be achieved at the tail of the furrow line. The solution is based on neglecting the recession and depletion times after off-irrigation. This assumption is valid in the case of open-end (free gradient) furrow systems rather than closed-end (closed dike) systems. Illustrative examples for different systems are presented and the results are compared with the output obtained using an iterative numerical solution method. The final derived solution is expressed as a function of the furrow length ratio (the furrow length to the water travelling distance). The function of water travelling developed by Reddy et al. is considered for reaching the optimum solution. As practical results from the study, the optimum furrow elements for free gradient systems can be estimated to achieve the maximum application efficiency, i.e. furrow length, water inflow rate and cutoff irrigation time.
Hierarchical distance-based fuzzy approach to evaluate urban water supply systems in a semi-arid region.

PubMed

Yekta, Tahereh Sadeghi; Khazaei, Mohammad; Nabizadeh, Ramin; Mahvi, Amir Hossein; Nasseri, Simin; Yari, Ahmad Reza

2015-01-01

Hierarchical distance-based fuzzy multi-criteria group decision making was served as a tool to evaluate the drinking water supply systems of Qom, a semi-arid city located in central part of Iran. A list of aspects consisting of 6 criteria and 35 sub-criteria were evaluated based on a linguistic term set by five decision-makers. Four water supply alternatives including "Public desalinated distribution system", "PET Bottled Drinking Water", "Private desalinated water suppliers" and "Household desalinated water units" were assessed based on criteria and sub-criteria. Data were aggregated and normalized to apply Performance Ratings of Alternatives. Also, the Performance Ratings of Alternatives were aggregated again to achieve the Aggregate Performance Ratings. The weighted distances from ideal solution and anti-ideal solution were calculated after secondary normalization. The proximity of each alternative to the ideal solution was determined as the final step. The alternatives were ranked based on the magnitude of ideal solutions. Results showed that "Public desalinated distribution system" was the most appropriate alternative to supply the drinking needs of Qom population. Also, "PET Bottled Drinking Water" was the second acceptable option. A novel classification of alternatives to satisfy the drinking water requirements was proposed which is applicable for the other cities located in semi-arid regions of Iran. The health issues were considered as independent criterion, distinct from the environmental issues. The constraints of high-tech alternatives were also considered regarding to the level of dependency on overseas.
Water age and stream solute dynamics at the Hubbard Brook Experimental Forest (US)

NASA Astrophysics Data System (ADS)

Botter, Gianluca; Benettin, Paolo; McGuire, Kevin; Rinaldo, Andrea

2016-04-01

The contribution discusses experimental and modeling results from a headwater catchment at the Hubbard Brook Experimental Forest (New Hampshire, USA) to explore the link between stream solute dynamics and water age. A theoretical framework based on water age dynamics, which represents a general basis for characterizing solute transport at the catchment scale, is used to model both conservative and weathering-derived solutes. Based on the available information about the hydrology of the site, an integrated transport model was developed and used to estimate the relevant hydrochemical fluxes. The model was designed to reproduce the deuterium content of streamflow and allowed for the estimate of catchment water storage and dynamic travel time distributions (TTDs). Within this framework, dissolved silicon and sodium concentration in streamflow were simulated by implementing first-order chemical kinetics based explicitly on dynamic TTD, thus upscaling local geochemical processes to catchment scale. Our results highlight the key role of water stored within the subsoil glacial material in both the short-term and long-term solute circulation at Hubbard Brook. The analysis of the results provided by the calibrated model allowed a robust estimate of the emerging concentration-discharge relationship, streamflow age distributions (including the fraction of event water) and storage size, and their evolution in time due to hydrologic variability.
Water and solute absorption from carbohydrate-electrolyte solutions in the human proximal small intestine: a review and statistical analysis.

PubMed

Shi, Xiaocai; Passe, Dennis H

2010-10-01

The purpose of this study is to summarize water, carbohydrate (CHO), and electrolyte absorption from carbohydrate-electrolyte (CHO-E) solutions based on all of the triple-lumen-perfusion studies in humans since the early 1960s. The current statistical analysis included 30 reports from which were obtained information on water absorption, CHO absorption, total solute absorption, CHO concentration, CHO type, osmolality, sodium concentration, and sodium absorption in the different gut segments during exercise and at rest. Mean differences were assessed using independent-samples t tests. Exploratory multiple-regression analyses were conducted to create prediction models for intestinal water absorption. The factors influencing water and solute absorption are carefully evaluated and extensively discussed. The authors suggest that in the human proximal small intestine, water absorption is related to both total solute and CHO absorption; osmolality exerts various impacts on water absorption in the different segments; the multiple types of CHO in the ingested CHO-E solutions play a critical role in stimulating CHO, sodium, total solute, and water absorption; CHO concentration is negatively related to water absorption; and exercise may result in greater water absorption than rest. A potential regression model for predicting water absorption is also proposed for future research and practical application. In conclusion, water absorption in the human small intestine is influenced by osmolality, solute absorption, and the anatomical structures of gut segments. Multiple types of CHO in a CHO-E solution facilitate water absorption by stimulating CHO and solute absorption and lowering osmolality in the intestinal lumen.
Conformational equilibria of alkanes in aqueous solution: relationship to water structure near hydrophobic solutes.

PubMed Central

Ashbaugh, H S; Garde, S; Hummer, G; Kaler, E W; Paulaitis, M E

1999-01-01

Conformational free energies of butane, pentane, and hexane in water are calculated from molecular simulations with explicit waters and from a simple molecular theory in which the local hydration structure is estimated based on a proximity approximation. This proximity approximation uses only the two nearest carbon atoms on the alkane to predict the local water density at a given point in space. Conformational free energies of hydration are subsequently calculated using a free energy perturbation method. Quantitative agreement is found between the free energies obtained from simulations and theory. Moreover, free energy calculations using this proximity approximation are approximately four orders of magnitude faster than those based on explicit water simulations. Our results demonstrate the accuracy and utility of the proximity approximation for predicting water structure as the basis for a quantitative description of n-alkane conformational equilibria in water. In addition, the proximity approximation provides a molecular foundation for extending predictions of water structure and hydration thermodynamic properties of simple hydrophobic solutes to larger clusters or assemblies of hydrophobic solutes. PMID:10423414

Linking water age and solute dynamics in streamflow at the Hubbard Brook Experimental Forest, NH, USA

Treesearch

Paolo Benettin; Scott W. Bailey; John L. Campbell; Mark B. Green; Andrea Rinaldo; Gene E. Likens; Kevin J. McGuire; Gianluca Botter

2015-01-01

We combine experimental and modeling results from a headwater catchment at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, to explore the link between stream solute dynamics and water age. A theoretical framework based on water age dynamics, which represents a general basis for characterizing solute transport at the catchment scale, is here applied to...
Development of a Polarizable Force Field for Molecular Dynamics Simulations of Poly (Ethylene Oxide) in Aqueous Solution.

PubMed

Starovoytov, Oleg N; Borodin, Oleg; Bedrov, Dmitry; Smith, Grant D

2011-06-14

We have developed a quantum chemistry-based polarizable potential for poly(ethylene oxide) (PEO) in aqueous solution based on the APPLE&P polarizable ether and the SWM4-DP polarizable water models. Ether-water interactions were parametrized to reproduce the binding energy of water with 1,2-dimethoxyethane (DME) determined from high-level quantum chemistry calculations. Simulations of DME-water and PEO-water solutions at room temperature using the new polarizable potentials yielded thermodynamic properties in good agreement with experimental results. The predicted miscibility of PEO and water as a function of the temperature was found to be strongly correlated with the predicted free energy of solvation of DME. The developed nonbonded force field parameters were found to be transferrable to poly(propylene oxide) (PPO), as confirmed by capturing, at least qualitatively, the miscibility of PPO in water as a function of the molecular weight.
Behavior of pure gallium in water and various saline solutions.

PubMed

Horasawa, N; Nakajima, H; Takahashi, S; Okabe, T

1997-12-01

This study investigated the chemical stability of pure gallium in water and saline solutions in order to obtain fundamental knowledge about the corrosion mechanism of gallium-based alloys. A pure gallium plate (99.999%) was suspended in 50 mL of deionized water, 0.01%, 0.1% or 1% NaCl solution at 24 +/- 2 degrees C for 1, 7, or 28 days. The amounts of gallium released into the solutions were determined by atomic absorption spectrophotometry. The surfaces of the specimens were examined after immersion by x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). In the solutions containing 0.1% or more NaCl, the release of gallium ions into the solution was lowered when compared to deionized water after 28-day immersion. Gallium oxide monohydroxide was found by XRD on the specimens immersed in deionized water after 28-day immersion. XPS indicated the formation of gallium oxide/hydroxide on the specimens immersed in water or 0.01% NaCl solution. The chemical stability of pure solid gallium was strongly affected by the presence of Cl- ions in the aqueous solution.
Electrochemical Ion-Exchange Regeneration and Fluidized Bed Crystallization for Zero-Liquid-Discharge Water Softening.

PubMed

Chen, Yingying; Davis, Jake R; Nguyen, Chi H; Baygents, James C; Farrell, James

2016-06-07

This research investigated the use of an electrochemical system for regenerating ion-exchange media and for promoting the crystallization of hardness minerals in a fluidized bed crystallization reactor (FBCR). The closed-loop process eliminates the creation of waste brine solutions that are normally produced when regenerating ion-exchange media. A bipolar membrane electrodialysis stack was used to generate acids and bases from 100 mM salt solutions. The acid was used to regenerate weak acid cation (WAC) ion-exchange media used for water softening. The base solutions were used to absorb CO2 gas and to provide a source of alkalinity for removing noncarbonate hardness by WAC media operated in H(+) form. The base solutions were also used to promote the crystallization of CaCO3 and Mg(OH)2 in a FBCR. The overall process removes hardness ions from the water being softened and replaces them with H(+) ions, slightly decreasing the pH value of the softened water. The current utilization efficiency for acid and base production was ∼75% over the operational range of interest, and the energy costs for producing acids and bases were an order of magnitude lower than the costs for purchasing acid and base in bulk quantities. Ion balances indicate that the closed-loop system will accumulate SO4(2-), Cl(-), and alkali metal ions. Acid and base balances indicate that for a typical water, small amounts of base will be accumulated.
Reactive solute transport in streams: 1. Development of an equilibrium- based model

USGS Publications Warehouse

Runkel, Robert L.; Bencala, Kenneth E.; Broshears, Robert E.; Chapra, Steven C.

1996-01-01

An equilibrium-based solute transport model is developed for the simulation of trace metal fate and transport in streams. The model is formed by coupling a solute transport model with a chemical equilibrium submodel based on MINTEQ. The solute transport model considers the physical processes of advection, dispersion, lateral inflow, and transient storage, while the equilibrium submodel considers the speciation and complexation of aqueous species, precipitation/dissolution and sorption. Within the model, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (water-borne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach.
Water-enhanced solvation of organics

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

Lee, Jane H.

1993-07-01

Water-enhanced solvation (WES) was explored for Lewis acid solutes in Lewis base organic solvents, to develop cheap extract regeneration processes. WES for solid solutes was determined from ratios of solubilities of solutes in water-sat. and low-water solvent; both were determined from solid-liquid equilibrium. Vapor-headspace analysis was used to determine solute activity coefficients as function of organic phase water concentration. WES magnitudes of volatile solutes were normalized, set equal to slope of log γ s vs x w/x s curve. From graph shape Δ(log γ s) represents relative change in solute activity coefficient. Solutes investigated by vapor-headspace analysis were acetic acid,more » propionic acid, ethanol, 1,2-propylene glycol, 2,3-butylene glycol. Monocarboxylic acids had largest decrease in activity coefficient with water addition followed by glycols and alcohols. Propionic acid in cyclohexanone showed greatest water-enhancement Δ(log γ acid)/Δ(x w/x acid) = -0.25. In methylcyclohexanone, the decrease of the activity coefficient of propionic acid was -0.19. Activity coefficient of propionic acid in methylcyclohexanone stopped decreasing once the water reached a 2:1 water to acid mole ratio, implying a stoichiometric relation between water, ketone, and acid. Except for 2,3-butanediol, activity coefficients of the solutes studied decreased monotonically with water content. Activity coefficient curves of ethanol, 1,2-propanediol and 2,3-butanediol did not level off at large water/solute mole ratio. Solutes investigated by solid-liquid equilibrium were citric acid, gallic acid, phenol, xylenols, 2-naphthol. Saturation concentration of citric acid in anhydrous butyl acetate increased from 0.0009 to 0.087 mol/L after 1.3 % (g/g) water co-dissolved into organic phase. Effect of water-enhanced solvation for citric acid is very large but very small for phenol and its derivatives.« less
Intestinal "bioavailability" of solutes and water: we know how but not why.

PubMed Central

Charney, A. N.

1996-01-01

Only minimal quantities of ingested and normally secreted solutes and water are excreted in the stool. This near 100% bioavailability means that the diet and kidneys are relatively more important determinants of solute, water and acid-base balance than the intestine. Intestinal bioavailability is based on excess transport capacity under normal conditions and the ability to adapt to altered or abnormal conditions. Indeed, the regulatory system of the intestine is as complex, segmented and multi factorial as in the kidney. Alterations in the rate and intestinal site of absorption reflect this regulation, and the diagnosis and treatment of various clinical abnormalities depend on the integrity of intestinal absorptive processes. However, the basis for this regulation an bioavailability are uncertain. Perhaps they had survival value for mammals, a phylogenic class that faced the twin threats of intestinal pathogens and shortages of solutes and water. PMID:9273987
An analytical solution for predicting the transient seepage from a subsurface drainage system

NASA Astrophysics Data System (ADS)

Xin, Pei; Dan, Han-Cheng; Zhou, Tingzhang; Lu, Chunhui; Kong, Jun; Li, Ling

2016-05-01

Subsurface drainage systems have been widely used to deal with soil salinization and waterlogging problems around the world. In this paper, a mathematical model was introduced to quantify the transient behavior of the groundwater table and the seepage from a subsurface drainage system. Based on the assumption of a hydrostatic pressure distribution, the model considered the pore-water flow in both the phreatic and vadose soil zones. An approximate analytical solution for the model was derived to quantify the drainage of soils which were initially water-saturated. The analytical solution was validated against laboratory experiments and a 2-D Richards equation-based model, and found to predict well the transient water seepage from the subsurface drainage system. A saturated flow-based model was also tested and found to over-predict the time required for drainage and the total water seepage by nearly one order of magnitude, in comparison with the experimental results and the present analytical solution. During drainage, a vadose zone with a significant water storage capacity developed above the phreatic surface. A considerable amount of water still remained in the vadose zone at the steady state with the water table situated at the drain bottom. Sensitivity analyses demonstrated that effects of the vadose zone were intensified with an increased thickness of capillary fringe, capillary rise and/or burying depth of drains, in terms of the required drainage time and total water seepage. The analytical solution provides guidance for assessing the capillary effects on the effectiveness and efficiency of subsurface drainage systems for combating soil salinization and waterlogging problems.
Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

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

Song, Jin; Kim, Dohyun, E-mail: dohyun.kim@mju.ac.kr; Chung, Minsub

2015-01-15

We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (−5.1 °C/s) and a low freezing temperature (−14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.
A novel polymer inclusion membrane based method for continuous clean-up of thiocyanate from gold mine tailings water.

PubMed

Cho, Youngsoo; Cattrall, Robert W; Kolev, Spas D

2018-01-05

Thiocyanate is present in gold mine tailings waters in concentrations up to 1000mgL -1 and this has a serious environmental impact by not allowing water reuse in the flotation of gold ore. This significantly increases the consumption of fresh water and the amount of wastewater discharged in tailings dams. At the same time thiocyanate in tailings waters often leads to groundwater contamination. A novel continuous membrane-based method for the complete clean-up of thiocyanate in concentrations as high as 1000mgL -1 from its aqueous solutions has been developed. It employs a flat sheet polymer inclusion membrane (PIM) of composition 70wt% PVC, 20wt% Aliquat 336 and 10wt% 1-tetradecanol which separates counter-current streams of a feed thiocyanate solution and a 1M NaNO 3 receiving solution. The PIM-based system has been operated continuously for 45days with 99% separation efficiency. The volume of the receiving solution has been drastically reduced by recirculating it and continuously removing thiocyanate by precipitating it with in-situ generated Cu(I). The newly developed PIM-based thiocyanate clean-up method is environmentally friendly in terms of reagent use and inexpensive with respect to both equipment and running costs. Copyright © 2017 Elsevier B.V. All rights reserved.
Solvent wash solution

DOEpatents

Neace, J.C.

1984-03-13

A process is claimed for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 vol % of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.
Solvent wash solution

DOEpatents

Neace, James C.

1986-01-01

Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.
Simplified multiple scattering model for radiative transfer in turbid water

NASA Technical Reports Server (NTRS)

Ghovanlou, A. H.; Gupta, G. N.

1978-01-01

Quantitative analytical procedures for relating selected water quality parameters to the characteristics of the backscattered signals, measured by remote sensors, require the solution of the radiative transport equation in turbid media. Presented is an approximate closed form solution of this equation and based on this solution, the remote sensing of sediments is discussed. The results are compared with other standard closed form solutions such as quasi-single scattering approximations.
Real-solution stability diagrams: A thermodynamic tool for modeling corrosion in wide temperature and concentration ranges

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

Anderko, A.; Sanders, S.J.; Young, R.D.

1997-01-01

A method was developed for construction of stability diagrams for metals in the presence of realistically modeled aqueous solutions. The method was based on a comprehensive thermodynamic model that combines the Helgeson-Kirkham-Flowers (HKF) equation of state for standard-state properties with a solution nonideality model based on the activity coefficient expressions developed by Bromley and Pitzer. Composition-dependent nonideality effects were incorporated into the calculation of predominance areas for dissolved and solid species. Using the combined thermodynamic model, stability diagrams can be computed for systems involving concentrated solutions (i.e., with molalities up to 30 mol/kg) at temperatures up to 573 K andmore » pressures up to 100 MPa. Since the diagrams are based on a realistic thermodynamic model for the aqueous phase, they are referred to as real-solution stability diagrams. In addition to customary potential (E) and pH variables, concentrations of various active species (e.g., complexing agents) can be used as independent variables, making it possible to analyze effects of various compounds that promote or inhibit corrosion. Usefulness of the methodology was demonstrated by generating real-solution stability diagrams for five representative systems (i.e., sulfur-water [S-H{sub 2}O], copper-ammonia-water [Cu-NH{sub 3}-H{sub 2}O], titanium-chlorine-calcium-water [Ti-Cl-Ca-H{sub 2}O], iron-sulfur-water [Fe-S-H{sub 2}O], and zinc-water [Zn-H{sub 2}O]).« less
A new unconditionally stable and consistent quasi-analytical in-stream water quality solution scheme for CSTR-based water quality simulators

NASA Astrophysics Data System (ADS)

Woldegiorgis, Befekadu Taddesse; van Griensven, Ann; Pereira, Fernando; Bauwens, Willy

2017-06-01

Most common numerical solutions used in CSTR-based in-stream water quality simulators are susceptible to instabilities and/or solution inconsistencies. Usually, they cope with instability problems by adopting computationally expensive small time steps. However, some simulators use fixed computation time steps and hence do not have the flexibility to do so. This paper presents a novel quasi-analytical solution for CSTR-based water quality simulators of an unsteady system. The robustness of the new method is compared with the commonly used fourth-order Runge-Kutta methods, the Euler method and three versions of the SWAT model (SWAT2012, SWAT-TCEQ, and ESWAT). The performance of each method is tested for different hypothetical experiments. Besides the hypothetical data, a real case study is used for comparison. The growth factors we derived as stability measures for the different methods and the R-factor—considered as a consistency measure—turned out to be very useful for determining the most robust method. The new method outperformed all the numerical methods used in the hypothetical comparisons. The application for the Zenne River (Belgium) shows that the new method provides stable and consistent BOD simulations whereas the SWAT2012 model is shown to be unstable for the standard daily computation time step. The new method unconditionally simulates robust solutions. Therefore, it is a reliable scheme for CSTR-based water quality simulators that use first-order reaction formulations.
Equilibrium water and solute uptake in silicone hydrogels.

PubMed

Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

2015-05-01

Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Cryopreservation of boar sperm comparing different cryoprotectants associated in media based on powdered coconut water, lactose and trehalose.

PubMed

Silva, C G; Cunha, E R; Blume, G R; Malaquias, J V; Báo, S N; Martins, C F

2015-04-01

In swine spermatozoa, the damage caused by cryopreservation is more severe than other species, provoking reduced potential for fertilization. Adjustments in the freezing extender composition may be an important alternative to increase its efficiency. The objective of this study was to test the efficiency of different cryoprotectant solutions during cryopreservation of swine semen with a controlled cooling curve. Three cryoprotectant solutions (5% dimethylformamide, 3% glycerol and the combination of these two cryoprotectants) were used in association with three base media (powdered coconut water, lactose and trehalose), constituting nine different treatments. The semen was frozen using a controlled-rate freezer (TK-3000). After thawing, semen was evaluated for total sperm motility, vigor, morphology, plasma membrane integrity and acrosome integrity. Cryopreservation with the controlled curve using an automated system showed satisfactory results, guaranteeing practicality and repeatability for the process of freezing swine sperm. With this curve, the solutions of lactose, trehalose and powdered coconut water associated with glycerol, as well as the solution of coconut water containing dimethylformamide, presented higher quality of sperm compared to the other solutions. Powdered coconut water associated with dimethylformamide appears as a new solution for swine sperm cryopreservation. The freezing controlled curve used in this study allowed standardization of the cryopreservation technique. Copyright © 2015 Elsevier Inc. All rights reserved.
Calibration of equipment for analysis of drinking water fluoride: a comparison study.

PubMed

Quock, Ryan L; Chan, Jarvis T

2012-03-01

Current American Dental Association evidence-based recommendations for prescription of dietary fluoride supplements are based in part on the fluoride concentration of a pediatric patient's drinking water. With these recommendations in mind, this study compared the relative accuracy of fluoride concentration analysis when a common apparatus is calibrated with different combinations of standard values. Fluoride solutions in increments of 0.1 ppm, from a range of 0.1 to 1.0 ppm fluoride, as well as 2.0 and 4.0 ppm, were gravimetrically prepared and fluoride concentration measured in pentad, using a fluoride ion-specific electrode and millivolt meter. Fluoride concentrations of these solutions were recorded after calibration with the following 3 different combinations of standard fluoride solutions: 0.1 ppm and 0.5 ppm, 0.1 ppm and 1.0 ppm, 0.5 ppm and 1.0 ppm. Statistical analysis showed significant differences in the fluoride content of water samples obtained with different two-standard fluoride solutions. Among the two-standard fluoride solutions tested, using 0.5 ppm and 1.0 ppm as two-standard fluoride solutions provided the most accurate fluoride measurement of water samples containing fluoride in the range of 0.1 ppm to 4.0 ppm. This information should be valuable to dental clinics or laboratories in fluoride analysis of drinking water samples.
Using Grand Canonical Monte Carlo Simulations to Understand the Role of Interfacial Fluctuations on Solvation at the Water-Vapor Interface.

PubMed

Rane, Kaustubh; van der Vegt, Nico F A

2016-09-15

The present work investigates the effect of interfacial fluctuations (predominantly capillary wave-like fluctuations) on the solvation free energy (Δμ) of a monatomic solute at the water-vapor interface. We introduce a grand-canonical-ensemble-based simulation approach that quantifies the contribution of interfacial fluctuations to Δμ. This approach is used to understand how the above contribution depends on the strength of dispersive and electrostatic solute-water interactions at the temperature of 400 K. At this temperature, we observe that interfacial fluctuations do play a role in the variation of Δμ with the strength of the electrostatic solute-water interaction. We also use grand canonical simulations to further investigate how interfacial fluctuations affect the propensity of the solute toward the water-vapor interface. To this end, we track a quantity called the interface potential (surface excess free energy) with the number of water molecules. With increasing number of water molecules, the liquid-vapor interface moves across a solute, which is kept at a fixed position in the simulation. Hence, the dependence of the interface potential on the number of waters models the process of moving the solute through the water-vapor interface. We analyze the change of the interface potential with the number of water molecules to explain that solute-induced changes in the interfacial fluctuations, like the pinning of capillary-wave-like undulations, do not play any role in the propensity of solutes toward water-vapor interfaces. The above analysis also shows that the dampening of interfacial fluctuations accompanies the adsorption of any solute at the liquid-vapor interface, irrespective of the chemical nature of the solute and solvent. However, such a correlation does not imply that dampening of fluctuations causes adsorption.
Evaporation of Binary Sessile Drops: Infrared and Acoustic Methods To Track Alcohol Concentration at the Interface and on the Surface.

PubMed

Chen, Pin; Toubal, Malika; Carlier, Julien; Harmand, Souad; Nongaillard, Bertrand; Bigerelle, Maxence

2016-09-27

Evaporation of droplets of three pure liquids (water, 1-butanol, and ethanol) and four binary solutions (5 wt % 1-butanol-water-based solution and 5, 25, and 50 wt % ethanol-water-based solutions) deposited on hydrophobic silicon was investigated. A drop shape analyzer was used to measure the contact angle, diameter, and volume of the droplets. An infrared camera was used for infrared thermal mapping of the droplet's surface. An acoustic high-frequency echography technique was, for the first time, applied to track the alcohol concentration in a binary-solution droplet. Evaporation of pure alcohol droplets was executed at different values of relative humidity (RH), among which the behavior of pure ethanol evaporation was notably influenced by the ambient humidity as a result of high hygrometry. Evaporation of droplets of water and binary solutions was performed at a temperature of 22 °C and a mean humidity of approximately 50%. The exhaustion times of alcohol in the droplets estimated by the acoustic method and the visual method were similar for the water-1-butanol mixture; however, the time estimated by the acoustic method was longer when compared with that estimated by the visual method for the water-ethanol mixture due to the residual ethanol at the bottom of the droplet.

Devices for monitoring content of microparticles and bacterium in injection solutions in pharmaceutical production

NASA Astrophysics Data System (ADS)

Bilyi, Olexander I.; Getman, Vasyl B.; Konyev, Fedir A.; Sapunkov, Olexander; Sapunkov, Pavlo G.

2001-06-01

The devices for monitoring of parameters of efficiency of water solutions filtration, which are based on the analysis of scattered light by microparticles are considered in this article. The efficiency of using of devices in pharmaceutics in technological processes of manufacturing medical injection solutions is shown. The examples of monitoring of contents of bacterial cultures Pseudomonas aeruginosa, Escherichia coli, and Micrococcus luteus in water solutions of glucose are indicated.
Extracting renewable energy from a salinity difference using a capacitor.

PubMed

Brogioli, Doriano

2009-07-31

Completely renewable energy can be produced by using water solutions of different salinity, like river water and sea water. Many different methods are already known, but development is still at prototype stage. Here I report a novel method, based on electric double-layer capacitor technology. Two porous electrodes, immersed in the salt solution, constitute a capacitor. It is first charged, then the salt solution is brought into contact with fresh water. The electrostatic energy increases as the salt concentration of the solution is reduced due to diffusion. This device can be used to turn sources of salinity difference into completely renewable sources of energy. An experimental demonstration is given, and performances and possible improvements are discussed.
Evaluating the potential of multi-purpose nature based solutions in peri-urban landscapes - a preliminary assessment

NASA Astrophysics Data System (ADS)

Geris, Josie; Wilkinson, Mark; Stutter, Marc; Guenther, Daniel; Soulsby, Chris

2016-04-01

Many communities across the world face the increasing challenge of balancing water quantity and quality protection and improvement with accommodating new growth and urban development. Urbanisation is typically associated with detrimental changes in water quality, sediment delivery, and effects on water storage and flow pathways (e.g. increases in flooding). Current mitigation solutions are typically based on isolated design strategies used at specific small scale sites and for storm water only. More holistic catchment scale approaches are urgently required to effectively manage the amount of water flows and protect the raw water quality in peri-urban landscapes. This project aims to provide a better understanding of the connectivity between natural and managed flow pathways, storage, and biogeochemical processes in the peri-urban landscape to eventually aid a more integrated water quantity and quality control design. For an actively urbanising catchment in NE Scotland we seek to understand the spatio-temporal character of the natural flow pathways and associated water quality, and how these may be used to support the design of nature based solutions during urbanisation. We present preliminary findings from a dense and multiscale monitoring network that includes hydrometric, tracer (stable water isotopes) and water quality (turbidity (sediment), nitrate, phosphate) data during a range of contrasting hydroclimatological conditions and at different stages of the development of urban infrastructure. These demonstrate a highly variable nature, both temporally and spatially, with water quality dynamics out of sync with storm responses and depending on management practices. This highlights potential difficulties for managing water quantity and quality simultaneously at the catchment scale, and suggests that a treatment train approach may be required. Well-designed nature based solutions that tackle both water quantity and quality issues will require adaptability and a focus on the whole spectrum of the flow regime.
Variable viscosity on unsteady dissipative Carreau fluid over a truncated cone filled with titanium alloy nanoparticles

NASA Astrophysics Data System (ADS)

Raju, C. S. K.; Sekhar, K. R.; Ibrahim, S. M.; Lorenzini, G.; Viswanatha Reddy, G.; Lorenzini, E.

2017-05-01

In this study, we proposed a theoretical investigation on the temperature-dependent viscosity effect on magnetohydrodynamic dissipative nanofluid over a truncated cone with heat source/sink. The involving set of nonlinear partial differential equations is transforming to set of nonlinear ordinary differential equations by using self-similarity solutions. The transformed governing equations are solved numerically using Runge-Kutta-based Newton's technique. The effects of various dimensionless parameters on the skin friction coefficient and the local Nusselt number profiles are discussed and presented with the support of graphs. We also obtained the validation of the current solutions with existing solution under some special cases. The water-based titanium alloy has a lesser friction factor coefficient as compared with kerosene-based titanium alloy, whereas the rate of heat transfer is higher in water-based titanium alloy compared with kerosene-based titanium alloy. From this we can highlight that depending on the industrial needs cooling/heating chooses the water- or kerosene-based titanium alloys.
Nanostructured protic ionic liquids retain nanoscale features in aqueous solution while precursor Brønsted acids and bases exhibit different behavior.

PubMed

Greaves, Tamar L; Kennedy, Danielle F; Weerawardena, Asoka; Tse, Nicholas M K; Kirby, Nigel; Drummond, Calum J

2011-03-10

Small- and wide-angle X-ray scattering (SWAXS) has been used to investigate the effect that water has on the nanoscale structure of protic ionic liquids (PILs) along with their precursor Brønsted acids and bases. The series of PILs consisted of primary, secondary, and tertiary alkylammonium cations in conjunction with formate, nitrate, or glycolate anions. Significant differences were observed for these systems. The nanoscale aggregates present in neat protic ionic liquids were shown to be stable in size on dilution to high concentrations of water, indicating that the water is localized in the ionic region and has little effect on the nonpolar domains. The Brønsted acid-water solutions did not display nanostructure at any water concentration. Primary amine Brønsted bases formed aggregates in water, which generally displayed characteristics of poorly structured microemulsions or a form of bicontinuous phase. Exceptions were butyl- and pentylamine with high water concentrations, for which the SWAXS patterns fitted well to the Teubner-Strey model for microemulsions. Brønsted base amines containing multiple alkyl chains or hydroxyl groups did not display nanostructure at any water concentration. IR spectroscopy was used to investigate the nature of water in the various solutions. For low PIL concentrations, the water was predominately present as bulk water for PIL molar fractions less than 0.4-0.5. At high PIL concentrations, in addition to the bulk water, there was a significant proportion of perturbed water, which is water influenced in some way by the cations and anions. The molecular state of the water in the studied amines was predominately present as bulk water, with smaller contributions from perturbed water than was seen in the PILs. © 2011 American Chemical Society
A simple approach to determine reactive solute transport using time domain reflectometry

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

Vogeler, I.; Duwig, C.; Clothier, B.E.

2000-02-01

Time domain reflectometry (TDR) possesses potential for determining solute-transport parameters, such as dispersion coefficients and retardation factors for reactive solutes. The authors developed a simple method based on peak-to-peak measurements of water and solute velocities through the soil using TDR. The method was tested by carrying out unsaturated leaching experiments in the laboratory on two soil columns packed with a South Pacific soil from Mare, which is a ferrasol with variable surface charge. One column was left bare and the other was planted with mustard. Pulses of CaBr{sub 2} and Ca(NO{sub 3}){minus}{sub 2} were applied to the surface of eithermore » wet or dry soil and then leached by water from a rainfall simulator applied at a steady rate of between 30 and 45 mm h{sup {minus}1}. Water and solute transport were monitored by collecting the effluent. Contemporaneous in situ measurements of the water content and electrical conductivity were made using TDR. Transport parameters for the convection-dispersion equation, with a linear adsorption isotherm, were obtained from the flux concentration and the solute resident concentrations measured by TDR. Anion retardations between 1.2 and 1.7, and dispersivities between 1 and 9 mm, were found. Retardations also were calculated using the authors simple approach based on TDR-measured water and solute front velocities. These used TDR measurements of soil water content and bulk soil electrical conductivity with time, and were similar to those obtained from the effluent. The agreement suggests TDR could be a valuable in situ technique for obtaining the parameters relating to reactive solute transport through soil.« less
Analytical steady-state solutions for water-limited cropping systems using saline irrigation water

NASA Astrophysics Data System (ADS)

Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

2014-12-01

Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess advantages over available alternatives, including: (i) the solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.
Ion-water wires in imidazolium-based ionic liquid/water solutions induce unique trends in density.

PubMed

Ghoshdastidar, Debostuti; Senapati, Sanjib

2016-03-28

Ionic liquid/water binary mixtures are rapidly gaining popularity as solvents for dissolution of cellulose, nucleobases, and other poorly water-soluble biomolecules. Hence, several studies have focused on measuring the thermophysical properties of these versatile mixtures. Among these, 1-ethyl-3-methylimidazolium ([emim]) cation-based ILs containing different anions exhibit unique density behaviours upon addition of water. While [emim][acetate]/water binary mixtures display an unusual rise in density with the addition of low-to-moderate amounts of water, those containing the [trifluoroacetate] ([Tfa]) anion display a sluggish decrease in density. The density of [emim][tetrafluoroborate] ([emim][BF4])/water mixtures, on the other hand, declines rapidly in close accordance with the experimental reports. Here, we unravel the structural basis underlying this unique density behavior of [emim]-based IL/water mixtures using all-atom molecular dynamics (MD) simulations. The results revealed that the distinct nature of anion-water hydrogen bonded networks in the three systems was a key in modulating the observed unique density behaviour. Vast expanses of uninterrupted anion-water-anion H-bonded stretches, denoted here as anion-water wires, induced significant structuring in [emim][Ac]/water mixtures that resulted in the density rise. Conversely, the presence of intermittent large water clusters disintegrated the anion-water wires in [emim][Tfa]/water and [emim][BF4]/water mixtures to cause a monotonic density decrease. The differential nanostructuring affected the dynamics of the solutions proportionately, with the H-bond making and breaking dynamics found to be greatly retarded in [emim][Ac]/water mixtures, while it exhibited a faster relaxation in the other two binary solutions.
Multiple periodic-soliton solutions of the (3+1)-dimensional generalised shallow water equation

NASA Astrophysics Data System (ADS)

Li, Ye-Zhou; Liu, Jian-Guo

2018-06-01

Based on the extended variable-coefficient homogeneous balance method and two new ansätz functions, we construct auto-Bäcklund transformation and multiple periodic-soliton solutions of (3 {+} 1)-dimensional generalised shallow water equations. Completely new periodic-soliton solutions including periodic cross-kink wave, periodic two-solitary wave and breather type of two-solitary wave are obtained. In addition, cross-kink three-soliton and cross-kink four-soliton solutions are derived. Furthermore, propagation characteristics and interactions of the obtained solutions are discussed and illustrated in figures.
Recrystallization of freezable bound water in aqueous solutions of medium concentration

NASA Astrophysics Data System (ADS)

Lishan, Zhao; Liqing, Pan; Ailing, Ji; Zexian, Cao; Qiang, Wang

2016-07-01

For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentration range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrystallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries. Project supported by the Knowledge Innovation Project of Chinese Academy of Sciences on Water Science Research (Grant No. KJZD-EW-M03) and the National Natural Science Foundation of China (Grant Nos. 11474325 and 11290161).
Process for separation and preconcentration of radium from water

DOEpatents

Dietz, Mark; Horwitz, E. Philip; Chiarizia, Renato; Bartsch, Richard A.

1999-01-01

A process for preconcentrating and separating radium from a contaminated solution containing at least water and radium includes the steps of adding a quantity of a water-soluble macrocyclic polyether to the contaminated solution to form a combined solution. An acid is added to the combined solution to form an acidic combined solution having an ›H.sup.+ ! concentration of about 0.5M. The acidic combined solution is contacted with a sulfonic acid-based strong acid cation exchange medium or a organophilic sulfonic acid medium having a plurality of binding sites thereon to bind the radium thereto and to form a radium-depleted solution. The radium-depleted solution is separated from the strong acid cation exchange medium or organophilic sulfonic acid medium. The radium remaining bound to the exchange medium or organophilic reagent is then stripped from the exchange medium or organophilic medium and the activity of the radium is measured.
Process for separation and preconcentration of radium from water

DOEpatents

Dietz, M.; Horwitz, E.P.; Chiarizia, R.; Bartsch, R.A.

1999-01-26

A process for preconcentrating and separating radium from a contaminated solution containing at least water and radium includes the steps of adding a quantity of a water-soluble macrocyclic polyether to the contaminated solution to form a combined solution. An acid is added to the combined solution to form an acidic combined solution having an [H{sup +}] concentration of about 0.5M. The acidic combined solution is contacted with a sulfonic acid-based strong acid cation exchange medium or a organophilic sulfonic acid medium having a plurality of binding sites thereon to bind the radium thereto and to form a radium-depleted solution. The radium-depleted solution is separated from the strong acid cation exchange medium or organophilic sulfonic acid medium. The radium remaining bound to the exchange medium or organophilic reagent is then stripped from the exchange medium or organophilic medium and the activity of the radium is measured. 24 figs.
Using a hybrid model to predict solute transfer from initially saturated soil into surface runoff with controlled drainage water.

PubMed

Tong, Juxiu; Hu, Bill X; Yang, Jinzhong; Zhu, Yan

2016-06-01

The mixing layer theory is not suitable for predicting solute transfer from initially saturated soil to surface runoff water under controlled drainage conditions. By coupling the mixing layer theory model with the numerical model Hydrus-1D, a hybrid solute transfer model has been proposed to predict soil solute transfer from an initially saturated soil into surface water, under controlled drainage water conditions. The model can also consider the increasing ponding water conditions on soil surface before surface runoff. The data of solute concentration in surface runoff and drainage water from a sand experiment is used as the reference experiment. The parameters for the water flow and solute transfer model and mixing layer depth under controlled drainage water condition are identified. Based on these identified parameters, the model is applied to another initially saturated sand experiment with constant and time-increasing mixing layer depth after surface runoff, under the controlled drainage water condition with lower drainage height at the bottom. The simulation results agree well with the observed data. Study results suggest that the hybrid model can accurately simulate the solute transfer from initially saturated soil into surface runoff under controlled drainage water condition. And it has been found that the prediction with increasing mixing layer depth is better than that with the constant one in the experiment with lower drainage condition. Since lower drainage condition and deeper ponded water depth result in later runoff start time, more solute sources in the mixing layer are needed for the surface water, and larger change rate results in the increasing mixing layer depth.
Solute Migration from the Aquifer Matrix into a Solution Conduit and the Reverse.

PubMed

Li, Guangquan; Field, Malcolm S

2016-09-01

A solution conduit has a permeable wall allowing for water exchange and solute transfer between the conduit and its surrounding aquifer matrix. In this paper, we use Laplace Transform to solve a one-dimensional equation constructed using the Euler approach to describe advective transport of solute in a conduit, a production-value problem. Both nonuniform cross-section of the conduit and nonuniform seepage at the conduit wall are considered in the solution. Physical analysis using the Lagrangian approach and a lumping method is performed to verify the solution. Two-way transfer between conduit water and matrix water is also investigated by using the solution for the production-value problem as a first-order approximation. The approximate solution agrees well with the exact solution if dimensionless travel time in the conduit is an order of magnitude smaller than unity. Our analytical solution is based on the assumption that the spatial and/or temporal heterogeneity in the wall solute flux is the dominant factor in the spreading of spring-breakthrough curves, and conduit dispersion is only a secondary mechanism. Such an approach can lead to the better understanding of water exchange and solute transfer between conduits and aquifer matrix. Euler and Lagrangian approaches are used to solve transport in conduit. Two-way transfer between conduit and matrix is investigated. The solution is applicable to transport in conduit of persisting solute from matrix. © 2016, National Ground Water Association.
Ionic current rectification in organic solutions with quartz nanopipettes.

PubMed

Yin, Xiaohong; Zhang, Shudong; Dong, Yitong; Liu, Shujuan; Gu, Jing; Chen, Ye; Zhang, Xin; Zhang, Xianhao; Shao, Yuanhua

2015-09-01

The study of behaviors of ionic current rectification (ICR) in organic solutions with quartz nanopipettes is reported. ICR can be observed even in organic solutions using quartz pipettes with diameters varied from several to dozens of nanometers, and the direction of ICR is quite different from the ICR observed in aqueous phase. The influences of pore size, electrolyte concentration, and surface charge on the ICR have been investigated carefully. Water in organic solutions affects the direction and extent of ICR significantly. Mechanisms about the formation of an electrical double layer (EDL) on silica in organic solutions with different amount of water have been proposed. An improved method, which can be employed to detect trace water in organic solutions, has been implemented based on Au ultramicroelectrodes with cathodic differential pulse stripping voltammetry.
The effect of sludge water treatment plant residuals on the properties of compressed brick

NASA Astrophysics Data System (ADS)

Shamsudin, Shamrul-Mar; Shahidan, S.; Azmi, M. A. M.; Ghaffar, S. A.; Ghani, M. B. Abdul; Saiful Bahari, N. A. A.; Zuki, S. S. M.

2017-11-01

The focus of this study is on the production of compressed bricks which contains sludge water treatment plant (SWTP) residuals obtained from SAJ. The main objective of this study is to utilise and incorporate discarded material (SWTP) in the form of residual solution to produce compressed bricks. This serves as one of the recycling efforts to conserve the environment. This study determined the optimum mix based on a mix ratio of 1:2:4 (cement: sand: soil) in the production of compressed bricks where 5 different mixes were investigated i. e. 0%, 5%, 10%, 20%, and 30% of water treatment plant residue solution. The production of the compressed bricks is in accordance with the Malaysian Standard MS 7.6: 1972 and British Standard BS 3921: 1985 - Compressive Strength & Water Absorption. After being moulded and air dried, the cured bricks were subjected to compression tests and water absorption tests. Based on the tests conducted, it was found that 20% of water treatment plant residue solution which is equivalent to 50% of soil content replacement with a mix composition of [10: cement] [20: sand] [20: soil] [20: water treatment plant residue solution] is the optimum mix. It was also observed that the bricks containing SWTP residuals were lighter in weight compared to the control specimens
Assessment on Experimental Bacterial Biofilms and in Clinical Practice of the Efficacy of Sampling Solutions for Microbiological Testing of Endoscopes

PubMed Central

Aumeran, C.; Thibert, E.; Chapelle, F. A.; Hennequin, C.; Lesens, O.

2012-01-01

Opinions differ on the value of microbiological testing of endoscopes, which varies according to the technique used. We compared the efficacy on bacterial biofilms of sampling solutions used for the surveillance of the contamination of endoscope channels. To compare efficacy, we used an experimental model of a 48-h Pseudomonas biofilm grown on endoscope internal tubing. Sampling of this experimental biofilm was performed with a Tween 80-lecithin-based solution, saline, and sterile water. We also performed a randomized prospective study during routine clinical practice in our hospital sampling randomly with two different solutions the endoscopes after reprocessing. Biofilm recovery expressed as a logarithmic ratio of bacteria recovered on bacteria initially present in biofilm was significantly more effective with the Tween 80-lecithin-based solution than with saline solution (P = 0.002) and sterile water (P = 0.002). There was no significant difference between saline and sterile water. In the randomized clinical study, the rates of endoscopes that were contaminated with the Tween 80-lecithin-based sampling solution and the saline were 8/25 and 1/25, respectively (P = 0.02), and the mean numbers of bacteria recovered were 281 and 19 CFU/100 ml (P = 0.001), respectively. In conclusion, the efficiency and therefore the value of the monitoring of endoscope reprocessing by microbiological cultures is dependent on the sampling solutions used. A sampling solution with a tensioactive action is more efficient than saline in detecting biofilm contamination of endoscopes. PMID:22170930
Analytical method for dissolved-organic carbon fractionation

USGS Publications Warehouse

Leenheer, Jerry A.; Huffman, Edward W. D.

1979-01-01

A standard procedure for analytical-scale dissolved organic carbon fractionation is presented, whereby dissolved organic carbon in water is first fractionated by a nonionic macroreticular resin into acid, base, and neutral hydrophobic organic solute fractions, and next fractionated by ion-exchange resins into acid, base, and neutral hydrophilic solute fractions. The hydrophobic solutes are defined as those sorbed on a nonionic, acrylic-ester macroreticular resin and are differentiated into acid, base, and nautral fractions by sorption/desorption controlled by pH adjustment. The hydrophilic bases are next sorbed on strong-acid ion-exchange resin, followed by sorption of hydrophilic acids on a strong-base ion-exchange resin. Hydrophilic neutrals are not sorbed and remain dissolved in the deionized water at the end of the fractionation procedure. The complete fractionation can be performed on a 200-milliliter filtered water sample, whose dissolved organic carbon content is 5-25 mg/L and whose specific conductance is less than 2,000 μmhos/cm at 25°C. The applications of dissolved organic carbon fractionation analysis range from field studies of changes of organic solute composition with synthetic fossil fuel production, to fundamental studies of the nature of sorption processes.
Optimality versus stability in water resource allocation.

PubMed

Read, Laura; Madani, Kaveh; Inanloo, Bahareh

2014-01-15

Water allocation is a growing concern in a developing world where limited resources like fresh water are in greater demand by more parties. Negotiations over allocations often involve multiple groups with disparate social, economic, and political status and needs, who are seeking a management solution for a wide range of demands. Optimization techniques for identifying the Pareto-optimal (social planner solution) to multi-criteria multi-participant problems are commonly implemented, although often reaching agreement for this solution is difficult. In negotiations with multiple-decision makers, parties who base decisions on individual rationality may find the social planner solution to be unfair, thus creating a need to evaluate the willingness to cooperate and practicality of a cooperative allocation solution, i.e., the solution's stability. This paper suggests seeking solutions for multi-participant resource allocation problems through an economics-based power index allocation method. This method can inform on allocation schemes that quantify a party's willingness to participate in a negotiation rather than opt for no agreement. Through comparison of the suggested method with a range of distance-based multi-criteria decision making rules, namely, least squares, MAXIMIN, MINIMAX, and compromise programming, this paper shows that optimality and stability can produce different allocation solutions. The mismatch between the socially-optimal alternative and the most stable alternative can potentially result in parties leaving the negotiation as they may be too dissatisfied with their resource share. This finding has important policy implications as it justifies why stakeholders may not accept the socially optimal solution in practice, and underlies the necessity of considering stability where it may be more appropriate to give up an unstable Pareto-optimal solution for an inferior stable one. Authors suggest assessing the stability of an allocation solution as an additional component to an analysis that seeks to distribute water in a negotiated process. Copyright © 2013 Elsevier Ltd. All rights reserved.
Annual estimates of water and solute export from 42 tributaries to the Yukon River

USGS Publications Warehouse

Frederick Zanden,; Suzanne P. Anderson,; Striegl, Robert G.

2012-01-01

Annual export of 11 major and trace solutes for the Yukon River is found to be accurately determined based on summing 42 tributary contributions. These findings provide the first published estimates of tributary specific distribution of solutes within the Yukon River basin. First, we show that annual discharge of the Yukon River can be computed by summing calculated annual discharges from 42 tributaries. Annual discharge for the tributaries is calculated from the basin area and average annual precipitation over that area using a previously published regional regression equation. Based on tributary inputs, we estimate an average annual discharge for the Yukon River of 210 km3 year–1. This value is within 1% of the average measured annual discharge at the U.S. Geological Survey gaging station near the river terminus at Pilot Station, AK, for water years 2001 through 2005. Next, annual loads for 11 solutes are determined by combining annual discharge with point measurements of solute concentrations in tributary river water. Based on the sum of solutes in tributary water, we find that the Yukon River discharges approximately 33 million metric tons of dissolved solids each year at Pilot Station. Discharged solutes are dominated by cations calcium and magnesium (5.65 × 109 and 1.42 × 109 g year–1) and anions bicarbonate and sulphate (17.3 × 109 and 5.40 × 109 g year–1). These loads compare well with loads calculated independently at the three continuous gaging stations along the Yukon River. These findings show how annual solute yields vary throughout a major subarctic river basin and that accurate estimates of total river export can be determined from calculated tributary contributions.

Effect of the pore water composition on the diffusive anion transport in argillaceous, low permeability sedimentary rocks

NASA Astrophysics Data System (ADS)

Wigger, Cornelia; Van Loon, Luc R.

2018-06-01

The effect of the pore water composition on the diffusive anion transport was studied for two different argillaceous, low permeability sedimentary rocks, Opalinus Clay (OPA) and Helvetic Marl (HM). The samples were saturated with different solutions with varying molar concentration and different main cations in the solution: NaCl based pore solutions and CaCl2 based pore solutions. The total porosity was measured by through-diffusion experiments with the neutral tracer HTO. Experiments performed in NaCl solutions resulted in a porosity of 0.12 for OPA and 0.03 for HM, and are consistent with results of the experiments in CaCl2 solutions. The total porosity was independent of the molar concentration, in contrast to the measured anion porosity, which increased with increasing molar concentration. It could further be observed that the pore solution based on the bivalent cation calcium shielded the negative surface charge stronger than the monovalent cation sodium, resulting in a larger measureable anion-accessible porosity in the case of CaCl2 solutions. The data was modelled based on an adapted Donnan approach of Birgersson and Karnland (2009). The model had to be adjusted with a permanent free, uncharged porosity, as well as with structural information on the permanent anion exclusion because of so-called bottleneck pores. Both parameters can only be evaluated from experiments. Nevertheless, taking these two adaptions into account, the effect of varying pore water compositions on the anion-accessible porosity of the investigated argillaceous rocks could be satisfactorily described.
Effect of the pore water composition on the diffusive anion transport in argillaceous, low permeability sedimentary rocks.

PubMed

Wigger, Cornelia; Van Loon, Luc R

2018-06-01

The effect of the pore water composition on the diffusive anion transport was studied for two different argillaceous, low permeability sedimentary rocks, Opalinus Clay (OPA) and Helvetic Marl (HM). The samples were saturated with different solutions with varying molar concentration and different main cations in the solution: NaCl based pore solutions and CaCl 2 based pore solutions. The total porosity was measured by through-diffusion experiments with the neutral tracer HTO. Experiments performed in NaCl solutions resulted in a porosity of 0.12 for OPA and 0.03 for HM, and are consistent with results of the experiments in CaCl 2 solutions. The total porosity was independent of the molar concentration, in contrast to the measured anion porosity, which increased with increasing molar concentration. It could further be observed that the pore solution based on the bivalent cation calcium shielded the negative surface charge stronger than the monovalent cation sodium, resulting in a larger measureable anion-accessible porosity in the case of CaCl 2 solutions. The data was modelled based on an adapted Donnan approach of Birgersson and Karnland (2009). The model had to be adjusted with a permanent free, uncharged porosity, as well as with structural information on the permanent anion exclusion because of so-called bottleneck pores. Both parameters can only be evaluated from experiments. Nevertheless, taking these two adaptions into account, the effect of varying pore water compositions on the anion-accessible porosity of the investigated argillaceous rocks could be satisfactorily described. Copyright © 2018 Elsevier B.V. All rights reserved.
A graph decomposition-based approach for water distribution network optimization

NASA Astrophysics Data System (ADS)

Zheng, Feifei; Simpson, Angus R.; Zecchin, Aaron C.; Deuerlein, Jochen W.

2013-04-01

A novel optimization approach for water distribution network design is proposed in this paper. Using graph theory algorithms, a full water network is first decomposed into different subnetworks based on the connectivity of the network's components. The original whole network is simplified to a directed augmented tree, in which the subnetworks are substituted by augmented nodes and directed links are created to connect them. Differential evolution (DE) is then employed to optimize each subnetwork based on the sequence specified by the assigned directed links in the augmented tree. Rather than optimizing the original network as a whole, the subnetworks are sequentially optimized by the DE algorithm. A solution choice table is established for each subnetwork (except for the subnetwork that includes a supply node) and the optimal solution of the original whole network is finally obtained by use of the solution choice tables. Furthermore, a preconditioning algorithm is applied to the subnetworks to produce an approximately optimal solution for the original whole network. This solution specifies promising regions for the final optimization algorithm to further optimize the subnetworks. Five water network case studies are used to demonstrate the effectiveness of the proposed optimization method. A standard DE algorithm (SDE) and a genetic algorithm (GA) are applied to each case study without network decomposition to enable a comparison with the proposed method. The results show that the proposed method consistently outperforms the SDE and GA (both with tuned parameters) in terms of both the solution quality and efficiency.
Selenium Adsorption To Aluminum-Based Water Treatment Residuals

EPA Science Inventory

Aluminum-based water treatment residuals (WTR) can adsorb water-and soil-borne P, As(V), As(III), and perchlorate, and may be able to adsorb excess environmental selenium. WTR, clay minerals, and amorphous aluminum hydroxide were shaken for 24 hours in selenate or selenite solut...
Multiobjective evolutionary optimization of water distribution systems: Exploiting diversity with infeasible solutions.

PubMed

Tanyimboh, Tiku T; Seyoum, Alemtsehay G

2016-12-01

This article investigates the computational efficiency of constraint handling in multi-objective evolutionary optimization algorithms for water distribution systems. The methodology investigated here encourages the co-existence and simultaneous development including crossbreeding of subpopulations of cost-effective feasible and infeasible solutions based on Pareto dominance. This yields a boundary search approach that also promotes diversity in the gene pool throughout the progress of the optimization by exploiting the full spectrum of non-dominated infeasible solutions. The relative effectiveness of small and moderate population sizes with respect to the number of decision variables is investigated also. The results reveal the optimization algorithm to be efficient, stable and robust. It found optimal and near-optimal solutions reliably and efficiently. The real-world system based optimization problem involved multiple variable head supply nodes, 29 fire-fighting flows, extended period simulation and multiple demand categories including water loss. The least cost solutions found satisfied the flow and pressure requirements consistently. The best solutions achieved indicative savings of 48.1% and 48.2% based on the cost of the pipes in the existing network, for populations of 200 and 1000, respectively. The population of 1000 achieved slightly better results overall. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems.

PubMed

Blok, Chris; Jackson, Brian E; Guo, Xianfeng; de Visser, Pieter H B; Marcelis, Leo F M

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15-17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems.
Maximum Plant Uptakes for Water, Nutrients, and Oxygen Are Not Always Met by Irrigation Rate and Distribution in Water-based Cultivation Systems

PubMed Central

Blok, Chris; Jackson, Brian E.; Guo, Xianfeng; de Visser, Pieter H. B.; Marcelis, Leo F. M.

2017-01-01

Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15–17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems. PMID:28443129
Facile Routes To Improve Performance of Solution-Processed Amorphous Metal Oxide Thin Film Transistors by Water Vapor Annealing.

PubMed

Park, Won-Tae; Son, Inyoung; Park, Hyun-Woo; Chung, Kwun-Bum; Xu, Yong; Lee, Taegweon; Noh, Yong-Young

2015-06-24

Here, we report on a simple and high-rate oxidization method for producing solution-based compound mixtures of indium zinc oxide (IZO) and indium gallium zinc oxide (IGZO) metal-oxide semiconductors (MOS) for thin-film transistor (TFT) applications. One of the issues for solution-based MOS fabrication is how to sufficiently oxidize the precursor in order to achieve high performance. As the oxidation rate of solution processing is lower than vacuum-based deposition such as sputtering, devices using solution-processed MOS exhibit relatively poorer performance. Therefore, we propose a method to prepare the metal-oxide precursor upon exposure to saturated water vapor in a closed volume for increasing the oxidization efficiency without requiring additional oxidizing agent. We found that the hydroxide rate of the MOS film exposed to water vapor is lower than when unexposed (≤18%). Hence, we successfully fabricated oxide TFTs with high electron mobility (27.9 cm(2)/V·s) and established a rapid process (annealing at 400 °C for 5 min) that is much shorter than the conventional as-deposited long-duration annealing (at 400 °C for 1 h) whose corresponding mobility is even lower (19.2 cm(2)/V·s).
Evaluation of the Determination of Free Urea in Water-Soluble Liquid Fertilizers Containing Urea and Ureaforms by Urease and HPLC Methods.

PubMed

Hojjatie, Michael M; Abrams, Dean

2015-01-01

Currently there are three AOAC Official Methods for the determination of urea in fertilizers. AOAC Official Method 959.03, Urea in Fertilizers, Urease Method, First Action 1959, Final Action 1960, is based on the use of fresh commercial 1% urease solution, or preparation of such solution from urease powder in water, or from jack bean meal in water. AOAC Official Method 983.01, Urea and Methyleneureas (Water-Soluble) in Fertilizers, First Action 1983, Final Action 1984, is based on LC with a refractive index detector using water as the mobile phase and a C18 column. AOAC Official Method 2003.14, Determination of Urea in Water- Soluble Urea-Formaldehyde Fertilizer Products and in Aqueous Urea Solutions, First Action 2003, Final Action 2008, is based on LC with a UV detector using acetonitrile-water (85+15, v/v) mobile phase and a propylamine column. The urea method, AOAC Official Method 959.03, is very much dependent on the nature of the urease enzyme. The method was developed in 1960 and used for simple urea fertilizer solutions. With the advent of complex fertilizer compositions, especially with the class of liquid triazone fertilizers and water-soluble urea forms, the analyses of free urea in these fertilizers by the urease method is often inaccurate and inconsistent. AOAC Official Method 983.01 is not always reliable due to the interference of some of the components of these fertilizers, and due to the fact that the use of water as the mobile phase does not always separate the free urea from other components. AOAC Official Method 2003.14 was subjected to ring test studies that showed it could be used for the determination of "free urea" in these classes of fertilizers with good accuracy and precision.
Characterization of superabsorbent hydrogel based on epichlorohydrin crosslink and carboxymethyl functionalization of cassava starch

NASA Astrophysics Data System (ADS)

Muharam, S.; Yuningsih, L. M.; Sumitra, M. R.

2017-07-01

Superabsorbent hydrogel was prepared by epichlorohydrin crosslink of cassava starch. Their swelling improved with added carboxymethyl group on the starch-epichlorohydrin structure. The structure and properties of starch-epichlorohydrin-carboxymethyl hydrogel were measured by SEM, FTIR, water and physiological solution absorption test and water retention test. The result showed that hydrogel displayed macroporous with heterogenous distribution and irregular surface was formed by epichlorohydrin and carboxymethyl bond in the structure of hydrogel. It was confirmed also by the FTIR spectra. The swelling ratio of starch-epichlorohydrin hydrogel to the water is 518 % and increased to 1,028.5 % with carboxymethyl addition on the structure. The best influence of the physiological solution to the swelling ratio of starch-epichlorohydrin-carboxymethyl hydrogel is urea solution. The water retention of starch-epichlorohydrin-carboxymethyl hydrogel in NaCl solution is better than in CaCl2 solution.
A scaled-ionic-charge simulation model that reproduces enhanced and suppressed water diffusion in aqueous salt solutions.

PubMed

Kann, Z R; Skinner, J L

2014-09-14

Non-polarizable models for ions and water quantitatively and qualitatively misrepresent the salt concentration dependence of water diffusion in electrolyte solutions. In particular, experiment shows that the water diffusion coefficient increases in the presence of salts of low charge density (e.g., CsI), whereas the results of simulations with non-polarizable models show a decrease of the water diffusion coefficient in all alkali halide solutions. We present a simple charge-scaling method based on the ratio of the solvent dielectric constants from simulation and experiment. Using an ion model that was developed independently of a solvent, i.e., in the crystalline solid, this method improves the water diffusion trends across a range of water models. When used with a good-quality water model, e.g., TIP4P/2005 or E3B, this method recovers the qualitative behaviour of the water diffusion trends. The model and method used were also shown to give good results for other structural and dynamic properties including solution density, radial distribution functions, and ion diffusion coefficients.
Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

PubMed Central

Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

2015-01-01

Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, . Here we report a universal water-content, , dependence of for aqueous solutions. Solutions with vitrify/devitrify at a constant temperature, , referring to freeze-concentrated phase with left behind ice crystallization. Those solutions with totally vitrify at under conventional cooling/heating process though, of the samples annealed at temperatures to effectively evoke ice recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution. PMID:26503911
Who to Blame: Irrational Decision-Makers or Stupid Modelers? (Arne Richter Award for Outstanding Young Scientists Lecture)

NASA Astrophysics Data System (ADS)

Madani, Kaveh

2016-04-01

Water management benefits from a suite of modelling tools and techniques that help simplifying and understanding the complexities involved in managing water resource systems. Early water management models were mainly concerned with optimizing a single objective, related to the design, operations or management of water resource systems (e.g. economic cost, hydroelectricity production, reliability of water deliveries). Significant improvements in methodologies, computational capacity, and data availability over the last decades have resulted in developing more complex water management models that can now incorporate multiple objectives, various uncertainties, and big data. These models provide an improved understanding of complex water resource systems and provide opportunities for making positive impacts. Nevertheless, there remains an alarming mismatch between the optimal solutions developed by these models and the decisions made by managers and stakeholders of water resource systems. Modelers continue to consider decision makers as irrational agents who fail to implement the optimal solutions developed by sophisticated and mathematically rigours water management models. On the other hand, decision makers and stakeholders accuse modelers of being idealist, lacking a perfect understanding of reality, and developing 'smart' solutions that are not practical (stable). In this talk I will have a closer look at the mismatch between the optimality and stability of solutions and argue that conventional water resources management models suffer inherently from a full-cooperation assumption. According to this assumption, water resources management decisions are based on group rationality where in practice decisions are often based on individual rationality, making the group's optimal solution unstable for individually rational decision makers. I discuss how game theory can be used as an appropriate framework for addressing the irrational "rationality assumption" of water resources management models and for better capturing the social aspects of decision making in water management systems with multiple stakeholders.
Nucleophilic stabilization of water-based reactive ink for titania-based thin film inkjet printing

NASA Astrophysics Data System (ADS)

Gadea, C.; Marani, D.; Esposito, V.

2017-02-01

Drop on demand deposition (DoD) of titanium oxide thin films (<500 nm) is performed via a novel titanium-alkoxide-based solution that is tailored as a reactive ink for inkjet printing. The ink is developed as water-based solution by a combined use of titanium isopropoxide and n-methyldiethanolamine (MDEA) used as nucleophilic ligand. The function of the ligand is to control the fast hydrolysis/condensation reactions in water for the metal alkoxide before deposition, leading to formation of the TiO2 only after the jet process. The evolution of the titanium-ligand interactions at increasing amount of MDEA is here elucidated in terms of long term stability. The ink printability parameter (Z) is optimized, resulting in a reactive solution with printability, Z, >1, and chemical stability up to 600 h. Thin titanium oxide films (<500 nm) are proved on different substrates. Pure anatase phase is obtained after annealing at low temperature (ca. 400 °C).
Migration through soil of organic solutes in an oil-shale process water

USGS Publications Warehouse

Leenheer, J.A.; Stuber, H.A.

1981-01-01

The migration through soil of organic solutes in an oil-shale process water (retort water) was studied by using soil columns and analyzing leachates for various organic constituents. Retort water extracted significant quantities of organic anions leached from ammonium-saturated-soil organic matter, and a distilled-water rinse, which followed retort-water leaching, released additional organic acids from the soil. After being corrected for organic constitutents extracted from soil by retort water, dissolved-organic-carbon fractionation analyses of effluent fractions showed that the order of increasing affinity of six organic compound classes for the soil was as follows: hydrophilic neutrals nearly equal to hydrophilic acids, followed by the sequence of hydrophobic acids, hydrophilic bases, hydrophobic bases, and hydrophobic neutrals. Liquid-chromatographic analysis of the aromatic amines in the hydrophobic- and hydrophilic-base fractions showed that the relative order of the rates of migration through the soil column was the same as the order of migration on a reversed-phase, octadecylsilica liquid-chromatographic column.
Inorganic-polymer-derived dielectric films

DOEpatents

Brinker, C.J.; Keefer, K.D.; Lenahan, P.M.

1985-02-25

A method is disclosed for coating a substrate with a thin film of a predetermined porosity. The method comprises: depositing the thin film on the substrate from a non-gelled solution comprising at least one metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base; prior to said depositing step, controlling the porosity and structure of said coating for a given composition of said solution exclusive of the acid or base component and the water component, by adjusting each of the water content, the pH, the temperature and the time of standing of said solution, increasing/descreasing the water content or the pH to increase/decrease the pore size of said coating, and increasing/decreasing the temperature or time of standing of said solution to increase/decrease the pore size of said coating; and curing said deposited film at a temperature effective for curing whereby there is obtained a thin film coating of a predetermined porosity on the substrate.
An analytical solution of Richards' equation providing the physical basis of SCS curve number method and its proportionality relationship

NASA Astrophysics Data System (ADS)

Hooshyar, Milad; Wang, Dingbao

2016-08-01

The empirical proportionality relationship, which indicates that the ratio of cumulative surface runoff and infiltration to their corresponding potentials are equal, is the basis of the extensively used Soil Conservation Service Curve Number (SCS-CN) method. The objective of this paper is to provide the physical basis of the SCS-CN method and its proportionality hypothesis from the infiltration excess runoff generation perspective. To achieve this purpose, an analytical solution of Richards' equation is derived for ponded infiltration in shallow water table environment under the following boundary conditions: (1) the soil is saturated at the land surface; and (2) there is a no-flux boundary which moves downward. The solution is established based on the assumptions of negligible gravitational effect, constant soil water diffusivity, and hydrostatic soil moisture profile between the no-flux boundary and water table. Based on the derived analytical solution, the proportionality hypothesis is a reasonable approximation for rainfall partitioning at the early stage of ponded infiltration in areas with a shallow water table for coarse textured soils.
Barometric fluctuations in wells tapping deep unconfined aquifers

USGS Publications Warehouse

Weeks, Edwin P.

1979-01-01

Water levels in wells screened only below the water table in unconfined aquifers fluctuate in response to atmospheric pressure changes. These fluctuations occur because the materials composing the unsaturated zone resist air movement and have capacity to store air with a change in pressure. Consequently, the translation of any pressure change at land surface is slowed as it moves through the unsaturated zone to the water table, but it reaches the water surface in the well instantaneously. Thus a pressure imbalance is created that results in a water level fluctuation. Barometric effects on water levels in unconfined aquifers can be computed by solution of the differential equation governing the flow of gas in the unsaturated zone subject to the appropriate boundary conditions. Solutions to this equation for two sets of boundary conditions were applied to compute water level response in a well tapping the Ogallala Formation near Lubbock, Texas from simultaneous microbarograph records. One set of computations, based on the step function unit response solution and convolution, resulted in a very good match between computed and measured water levels. A second set of computations, based on analysis of the amplitude ratios of simultaneous cyclic microbarograph and water level fluctuations, gave inconsistent results in terms of the unsaturated zone pneumatic properties but provided useful insights on the nature of unconfined-aquifer water level fluctuations.
The origin of high sodium bicarbonate waters in the Atlantic and Gulf Coastal Plains

USGS Publications Warehouse

Foster, M.D.

1950-01-01

Some sodium bicarbonate waters at depth in the Atlantic and Gulf Coastal Plains have the same bicarbonate content as the shallower calcium bicarbonate waters in the same formation and appear to be the result of replacement of calcium by sodium through the action of base-exchange minerals. Others, however, contain several hundred parts per million more of bicarbonate than any of the calcium bicarbonate waters and much more bicarbonate than can be attributed to solution of calcium carbonate through the action of carbon dioxide derived from the air and soil. As the waters in the Potomac group (Cretaceous) are all low in sulphate and as the environmental conditions under which the sediments of the Potomac group were deposited do not indicate that large amounts of sulphate are available for solution, it does not seem probable that carbon dioxide generated by chemical or biochemical breakdown of sulphate is responsible for the high sodium bicarbonate waters in this area. Sulphate as a source of oxygen is not necessary for the generation of carbon dioxide by carbonaceous material. Oxygen is an important constituent of carbonaceous material and carbon dioxide is a characteristic decomposition product of such material-as, for example, peat and lignite. Experimental work showed that distilled water, calcium bicarbonate water, and sodium bicarbonate water, after contact with lignite, calcium carbonate, and permutite (a base-exchange material), had all increased greatly in sodium bicarbonate content and had become similar in chemical character and in mineral content to high sodium bicarbonate waters found in the Coastal Plain. The tests indicated that carbonaceous material can act as a source of carbon dioxide, which, when dissolved in water, enables it to take into solution more calcium carbonate. If base-exchange materials are also present to replace calcium with sodium, a still greater amount of bicarbonate can be held in solution. The presence of carbonaceous material, together with calcium carbonate and base-exchange minerals in a formation is, therefore, sufficient to account for the occurrence in it of high sodium bicarbonate waters. ?? 1950.
Silicate-catalyzed chemical grouting compositions

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

Not Available

1972-09-28

Chemical grouting compositions for stabilizing earth, sand, and other porous particulate formations or agglomerates of solids are described. The composition for producing a chemically grouting structure consists of an aqueous base solution of: (1) vegetative polyphenolic material consisting of condensed type tannins, and an aqueous catalyst solution of (2) a water-soluble alkali metal silicate. The polyphenolic material is present in an amount from 5% to 40% based on the weight of the base solution, and the water- soluble alkali metal silicate is present in an amount to provide from 1% to 15% SiOD2U in the silicate compound based on themore » weight of the polyphenolic material. These grouting compositions are completely safe to operating personnel and to surrounding environment, since the potassium or sodium silicate catalysts are nontoxic. (15 claims)« less

Integrating participatory engagement and scientific research to inform causes and solutions to water problems in the River Njoro Watershed Kenya.

NASA Astrophysics Data System (ADS)

Jenkins, M.

2012-12-01

Over the course of 9 years, an international multidisciplinary team of US and Kenyan scientists under the Sustainable Management of Rural Watersheds (SUMAWA) Project, based at Egerton University in Kenya, worked with Kenyan public agencies to apply a variety of participatory methods and outreach activities combined with land use mapping, hydrologic and water system modeling, and other scientific tools and evaluations to investigate and identify solutions to declining water quantity and quality problems affecting communities and environmental and productive sectors in the River Njoro Watershed in Kenya. Traditional participatory rural appraisal techniques were modified to engage low income, informal, and tribal communities in identification of local services, benefits, and groups linked to water and riparian resources and collect their perceptions of water-related problems, priorities, and solution options throughout the watershed. Building on this foundation of insights, information, and engagement on water issues with local communities and other stakeholders, the project designed a research agenda aimed at creating shared scientific understanding of the causes of identified problems and developing and testing promising interventions to address community and stakeholder priority concerns. This presentation will share lessons from the SUMAWA experience of using a problem-driven, solution-oriented, community-based watershed approach to address water resource problems at local scale in a semi-arid African developing country setting.
Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations.

PubMed

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y; Schwegler, Eric

2016-10-21

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. Such simulations are often performed at elevated temperatures to artificially "correct" for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. To address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na + , K + , and Cl - ions. We show that simulations at 390-400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. Our results suggest that an elevated temperature around 390-400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.
Estimating system parameters for solvent-water and plant cuticle-water using quantum chemically estimated Abraham solute parameters.

PubMed

Liang, Yuzhen; Torralba-Sanchez, Tifany L; Di Toro, Dominic M

2018-04-18

Polyparameter Linear Free Energy Relationships (pp-LFERs) using Abraham system parameters have many useful applications. However, developing the Abraham system parameters depends on the availability and quality of the Abraham solute parameters. Using Quantum Chemically estimated Abraham solute Parameters (QCAP) is shown to produce pp-LFERs that have lower root mean square errors (RMSEs) of predictions for solvent-water partition coefficients than parameters that are estimated using other presently available methods. pp-LFERs system parameters are estimated for solvent-water, plant cuticle-water systems, and for novel compounds using QCAP solute parameters and experimental partition coefficients. Refitting the system parameter improves the calculation accuracy and eliminates the bias. Refitted models for solvent-water partition coefficients using QCAP solute parameters give better results (RMSE = 0.278 to 0.506 log units for 24 systems) than those based on ABSOLV (0.326 to 0.618) and QSPR (0.294 to 0.700) solute parameters. For munition constituents and munition-like compounds not included in the calibration of the refitted model, QCAP solute parameters produce pp-LFER models with much lower RMSEs for solvent-water partition coefficients (RMSE = 0.734 and 0.664 for original and refitted model, respectively) than ABSOLV (4.46 and 5.98) and QSPR (2.838 and 2.723). Refitting plant cuticle-water pp-LFER including munition constituents using QCAP solute parameters also results in lower RMSE (RMSE = 0.386) than that using ABSOLV (0.778) and QSPR (0.512) solute parameters. Therefore, for fitting a model in situations for which experimental data exist and system parameters can be re-estimated, or for which system parameters do not exist and need to be developed, QCAP is the quantum chemical method of choice.
Rapid and high-precision measurement of sulfur isotope and sulfur concentration in sediment pore water by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

2015-01-01

We have developed a technique for the rapid, precise and accurate determination of sulfur isotopes (δ(34)S) by MC-ICP-MS applicable to a range of sulfur-bearing solutions of different sulfur content. The 10 ppm Alfa-S solution (ammonium sulfate solution, working standard of the lab of the authors) was used to bracket other Alfa-S solutions of different concentrations and the measured δ(34)SV-CDT values of Alfa-S solutions deviate from the reference value to varying degrees (concentration effect). The stability of concentration effect has been verified and a correction curve has been constructed based on Alfa-S solutions to correct measured δ(34)SV-CDT values. The curve has been applied to AS solutions (dissolved ammonium sulfate from the lab of the authors) and pore water samples successfully, validating the reliability of our analytical method. This method also enables us to measure the sulfur concentration simultaneously when analyzing the sulfur isotope composition. There is a strong linear correlation (R(2)>0.999) between the sulfur concentrations and the intensity ratios of samples and the standard. We have constructed a regression curve based on Alfa-S solutions and this curve has been successfully used to determine sulfur concentrations of AS solutions and pore water samples. The analytical technique presented here enable rapid, precise and accurate S isotope measurement for a wide range of sulfur-bearing solutions - in particular for pore water samples with complex matrix and varying sulfur concentrations. Also, simultaneous measurement of sulfur concentrations is available. Copyright © 2014 Elsevier B.V. All rights reserved.
Direction of rational use of water at livestock facilities

NASA Astrophysics Data System (ADS)

Potseluev, A. A.; Nazarov, I. V.

2017-05-01

The article notes the world water shortage problem. Against this background, Russia’s agricultural production is considered, in particular the livestock sector as the main consumer of water resources. The structure of the main technological processes at livestock facilities is given and possible technological damage is indicated in case of the lack of technological processes for servicing animals and poultry with water. The direction of rational use of water based on the introduction of new technical and technological solutions of water supply systems and means is substantiated. Constructive solutions of systems and facilities that help to reduce water consumption are presented, and as well a possible positive effect.
Acid and base recovery from brine solution using PVP intermediate-based bipolar membrane through water splitting technology

NASA Astrophysics Data System (ADS)

Venugopal, Krishnaveni; Murugappan, Minnoli; Dharmalingam, Sangeetha

2017-07-01

Potable water has become a scarce resource in many countries. In fact, the world is not running out of water, but rather, the relatively fixed quantity is becoming too contaminated for many applications. Hence, the present work was designed to evaluate the desalination efficiency of resin and glass fiber-reinforced Polysulfone polymer-based monopolar and bipolar (BPM) ion exchange membranes (with polyvinyl pyrrolidone as the intermediate layer) on a real sample brine solution for 8 h duration. The prepared ion exchange membranes (IEMs) were characterized using FTIR, SEM, TGA, water absorption, and contact angle measurements. The BPM efficiency, electrical conductivity, salinity, sodium, and chloride ion concentration were evaluated for both prepared and commercial-based IEM systems. The current efficiency and energy consumption values obtained during BPMED process were found to be 45 % and 0.41 Wh for RPSu-PVP-based IEM system and 38 % and 1.60 Wh for PSDVB-based IEM system, respectively.
Inorganic-polymer-derived dielectric films

DOEpatents

Brinker, C. Jeffrey; Keefer, Keith D.; Lenahan, Patrick M.

1987-01-01

A method of coating a substrate with a thin film of a polymer of predetermined porosity comprises depositing the thin film on the substrate from a non-gelled solution comprising at least one hydrolyzable metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base, prior to depositing the film, controlling the structure of the polymer for a given composition of the solution exclusive of the acid or base component and the water component, (a) by adjusting each of the water content, the pH, and the temperature to obtain the desired concentration of alkoxide, and then adjusting the time of standing of the solution prior to lowering the temperature of the solution, and (b) lowering the temperature of the solution after the time of standing to about 15 degrees C. or lower to trap the solution in a state in which, after the depositing step, a coating of the desired porosity will be obtained, and curing the deposited film at a temperature effective for curing whereby there is obtained a thin film of a polymer of a predetermined porosity and corresponding pore size on the substrate.
Inactivation of Microbiological Contaminants in Drinking Water by Ultraviolet Light Technology: NeoTech Aqua Solutions, Inc.; Ultraviolet Water Treatment System, NeoTech D438™ (Report and VS)

EPA Science Inventory

The NeoTech Aqua Solutions, Inc. D438™ UV Water Treatment System was tested to validate the UV dose delivered by the system using biodosimetry and a set line approach. The set line for 40 mJ/cm2 measured Reduction Equivalent Dose (RED) was based on validation testing at three (3)...
Effects of Water on the Single-Chain Elasticity of Poly(U) RNA.

PubMed

Luo, Zhonglong; Cheng, Bo; Cui, Shuxun

2015-06-09

Water, the dominant component under the physiological condition, is a complicated solvent which greatly affects the properties of solute molecules. Here, we utilize atomic force microscope-based single-molecule force spectroscopy to study the influence of water on the single-molecule elasticity of an unstructured single-stranded RNA (poly(U)). In nonpolar solvents, RNA presents its inherent elasticity, which is consistent with the theoretical single-chain elasticity calculated by quantum mechanics calculations. In aqueous buffers, however, an additional energy of 1.88 kJ/mol·base is needed for the stretching of the ssRNA chain. This energy is consumed by the bound water rearrangement (Ew) during chain elongation. Further experimental results indicate that the Ew value is uncorrelated to the salt concentrations and stretching velocity. The results obtained in an 8 M guanidine·HCl solution provide more evidence that the bound water molecules around RNA give rise to the observed deviation between aqueous and nonaqueous environments. Compared to synthetic water-soluble polymers, the value of Ew of RNA is much lower. The weak interference of water is supposed to be the precondition for the RNA secondary structure to exist in aqueous solution.
Partition coefficients of organic compounds in lipid-water systems and correlations with fish bioconcentration factors

USGS Publications Warehouse

Chiou, C.T.

1985-01-01

Triolein-water partition coefficients (KtW) have been determined for 38 slightly water-soluble organic compounds, and their magnitudes have been compared with the corresponding octanol-water partition coefficients (KOW). In the absence of major solvent-solute interaction effects in the organic solvent phase, the conventional treatment (based on Raoult's law) predicts sharply lower partition coefficients for most of the solutes in triolein because of its considerably higher molecular weight, whereas the Flory-Huggins treatment predicts higher partition coefficients with triolein. The data are in much better agreement with the Flory-Huggins model. As expected from the similarity in the partition coefficients, the water solubility (which was previously found to be the major determinant of the KOW) is also the major determinant for the Ktw. When the published BCF values (bioconcentration factors) of organic compounds in fish are based on the lipid content rather than on total mass, they are approximately equal to the Ktw, which suggests at least near equilibrium for solute partitioning between water and fish lipid. The close correlation between Ktw and Kow suggests that Kow is also a good predictor for lipid-water partition coefficients and bioconcentration factors.
Preliminary study of coconut water for graft tissues preservation in transplantation.

PubMed

César, Jorge Miguel Schettino; Petroianu, Andy; Vasconcelos, Leonardo de Souza; Cardoso, Valbert Nascimento; Mota, Luciene das Graças; Barbosa, Alfredo José Afonso; Soares, Cristina Duarte Vianna; de Oliveira, Amanda Lima

2015-01-01

to verify the effectiveness of coconut water in preserving tissues for transplant. Fifty male Wistar rats were randomly distributed in five groups, according to the following preservation solutions for tissue grafts: Group 1: Lactated Ringer; Group 2: Belzer solution; Group 3: mature coconut water; Group 4: green coconut water; Group 5: modified coconut water. In Group 5, the green coconut water has been modified like the Belzer solution. From each animal we harvested the spleen, ovaries and skin of the back segment. These tissues were preserved for six hours in one of the solutions. Then, the grafts were reimplanted. The recovery of the function of the implanted tissues was assessed 90 days after surgery, by splenic scintigraphy and blood exam. The implanted tissues were collected for histopathological examination. The serum levels did not differ among groups, except for the animals in Group 5, which showed higher levels of IgG than Group 1, and differences in relation to FSH between groups 1 and 2 (p <0.001), 4 and 2 (p = 0.03) and 5 and 2 (p = 0.01). The splenic scintigraphy was not different between groups. The ovarian tissue was better preserved in mature coconut water (p <0.007). the coconut water-based solutions preserves spleen, ovary, and rat skin for six hours, maintaining their normal function.
A residual-based shock capturing scheme for the continuous/discontinuous spectral element solution of the 2D shallow water equations

NASA Astrophysics Data System (ADS)

Marras, Simone; Kopera, Michal A.; Constantinescu, Emil M.; Suckale, Jenny; Giraldo, Francis X.

2018-04-01

The high-order numerical solution of the non-linear shallow water equations is susceptible to Gibbs oscillations in the proximity of strong gradients. In this paper, we tackle this issue by presenting a shock capturing model based on the numerical residual of the solution. Via numerical tests, we demonstrate that the model removes the spurious oscillations in the proximity of strong wave fronts while preserving their strength. Furthermore, for coarse grids, it prevents energy from building up at small wave-numbers. When applied to the continuity equation to stabilize the water surface, the addition of the shock capturing scheme does not affect mass conservation. We found that our model improves the continuous and discontinuous Galerkin solutions alike in the proximity of sharp fronts propagating on wet surfaces. In the presence of wet/dry interfaces, however, the model needs to be enhanced with the addition of an inundation scheme which, however, we do not address in this paper.
Theoretical and experimental evidence of non-symmetric doubly localized rogue waves.

PubMed

He, Jingsong; Guo, Lijuan; Zhang, Yongshuai; Chabchoub, Amin

2014-11-08

We present determinant expressions for vector rogue wave (RW) solutions of the Manakov system, a two-component coupled nonlinear Schrödinger (NLS) equation. As a special case, we generate a family of exact and non-symmetric RW solutions of the NLS equation up to third order, localized in both space and time. The derived non-symmetric doubly localized second-order solution is generated experimentally in a water wave flume for deep-water conditions. Experimental results, confirming the characteristic non-symmetric pattern of the solution, are in very good agreement with theory as well as with numerical simulations, based on the modified NLS equation, known to model accurately the dynamics of weakly nonlinear wave packets in deep water.
Theoretical and experimental evidence of non-symmetric doubly localized rogue waves

PubMed Central

He, Jingsong; Guo, Lijuan; Zhang, Yongshuai; Chabchoub, Amin

2014-01-01

We present determinant expressions for vector rogue wave (RW) solutions of the Manakov system, a two-component coupled nonlinear Schrödinger (NLS) equation. As a special case, we generate a family of exact and non-symmetric RW solutions of the NLS equation up to third order, localized in both space and time. The derived non-symmetric doubly localized second-order solution is generated experimentally in a water wave flume for deep-water conditions. Experimental results, confirming the characteristic non-symmetric pattern of the solution, are in very good agreement with theory as well as with numerical simulations, based on the modified NLS equation, known to model accurately the dynamics of weakly nonlinear wave packets in deep water. PMID:25383023
Removal of metals from aqueous solution and sea water by functionalized graphite nanoplatelets based electrodes.

PubMed

Mishra, Ashish Kumar; Ramaprabhu, S

2011-01-15

In the present wok, we have demonstrated the simultaneous removal of sodium and arsenic (pentavalent and trivalent) from aqueous solution using functionalized graphite nanoplatelets (f-GNP) based electrodes. In addition, these electrodes based water filter was used for multiple metals removal from sea water. Graphite nanoplatelets (GNP) were prepared by acid intercalation and thermal exfoliation. Functionalization of GNP was done by further acid treatment. Material was characterized by different characterization techniques. Performance of supercapacitor based water filter was analyzed for the removal of high concentration of arsenic (trivalent and pentavalent) and sodium as well as for desalination of sea water, using cyclic voltametry (CV) and inductive coupled plasma-optical emission spectroscopy (ICP-OES) techniques. Adsorption isotherms and kinetic characteristics were studied for the simultaneous removal of sodium and arsenic (both trivalent and pentavalent). Maximum adsorption capacities of 27, 29 and 32 mg/g for arsenate, arsenite and sodium were achieved in addition to good removal efficiency for sodium, magnesium, calcium and potassium from sea water. Copyright © 2010 Elsevier B.V. All rights reserved.
Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions

NASA Astrophysics Data System (ADS)

Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

2016-08-01

We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells.
Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions.

PubMed

Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

2016-12-01

We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells.
Development of solute transport models in YMPYRÄ framework to simulate solute migration in military shooting and training areas

NASA Astrophysics Data System (ADS)

Warsta, L.; Karvonen, T.

2017-12-01

There are currently 25 shooting and training areas in Finland managed by The Finnish Defence Forces (FDF), where military activities can cause contamination of open waters and groundwater reservoirs. In the YMPYRÄ project, a computer software framework is being developed that combines existing open environmental data and proprietary information collected by FDF with computational models to investigate current and prevent future environmental problems. A data centric philosophy is followed in the development of the system, i.e. the models are updated and extended to handle available data from different areas. The results generated by the models are summarized as easily understandable flow and risk maps that can be opened in GIS programs and used in environmental assessments by experts. Substances investigated with the system include explosives and metals such as lead, and both surface and groundwater dominated areas can be simulated. The YMPYRÄ framework is composed of a three dimensional soil and groundwater flow model, several solute transport models and an uncertainty assessment system. Solute transport models in the framework include particle based, stream tube and finite volume based approaches. The models can be used to simulate solute dissolution from source area, transport in the unsaturated layers to groundwater and finally migration in groundwater to water extraction wells and springs. The models can be used to simulate advection, dispersion, equilibrium adsorption on soil particles, solubility and dissolution from solute phase and dendritic solute decay chains. Correct numerical solutions were confirmed by comparing results to analytical 1D and 2D solutions and by comparing the numerical solutions to each other. The particle based and stream tube type solute transport models were useful as they could complement the traditional finite volume based approach which in certain circumstances produced numerical dispersion due to piecewise solution of the governing equations in computational grids and included computationally intensive and in some cases unstable iterative solutions. The YMPYRÄ framework is being developed by WaterHope, Gain Oy, and SITO Oy consulting companies and funded by FDF.
Thermodynamic and Structural Properties of Methanol-Water Solutions Using Non-Additive Interaction Models

PubMed Central

Zhong, Yang; Warren, G. Lee; Patel, Sandeep

2014-01-01

We study bulk structural and thermodynamic properties of methanol-water solutions via molecular dynamics simulations using novel interaction potentials based on the charge equilibration (fluctuating charge) formalism to explicitly account for molecular polarization at the atomic level. The study uses the TIP4P-FQ potential for water-water interactions, and the CHARMM-based (Chemistry at HARvard Molecular Mechanics) fluctuating charge potential for methanol-methanol and methanol-water interactions. In terms of bulk solution properties, we discuss liquid densities, enthalpies of mixing, dielectric constants, self-diffusion constants, as well as structural properties related to local hydrogen bonding structure as manifested in radial distribution functions and cluster analysis. We further explore the electronic response of water and methanol in the differing local environments established by the interaction of each species predominantly with molecules of the other species. The current force field for the alcohol-water interaction performs reasonably well for most properties, with the greatest deviation from experiment observed for the excess mixing enthalpies, which are predicted to be too favorable. This is qualitatively consistent with the overestimation of the methanol-water gas-phase interaction energy for the lowest-energy conformer (methanol as proton donor). Hydration free energies for methanol in TIP4P-FQ water are predicted to be −5.6±0.2 kcal/mole, in respectable agreement with the experimental value of −5.1 kcal/mole. With respect to solution micro-structure, the present cluster analysis suggests that the micro-scale environment for concentrations where select thermodynamic quantities reach extremal values is described by a bi-percolating network structure. PMID:18074339
Towards the review of the European Union Water Framework ...

EPA Pesticide Factsheets

Water is a vital resource for natural ecosystems and human life, and assuring a high quality of water and protectingit from chemical contamination is a major societal goal in the European Union. The Water Framework Directive(WFD) and its daughter directives are the major body of legislation for the protection and sustainable use of Europeanfreshwater resources. The practical implementation of the WFD with regard to chemical pollution has facedsome challenges. In support of the upcoming WFD review in 2019 the research project SOLUTIONS and the Europeanmonitoring network NORMAN has analyzed these challenges, evaluated the state-of-the-art of the science andsuggested possible solutions. We give 10 recommendations to improve monitoring and to strengthen comprehensiveprioritization, to foster consistent assessment and to support solution-oriented management of surface waters.The integration of effect-based tools, the application of passive sampling for bioaccumulative chemicals and an integratedstrategy for prioritization of contaminants, accounting for knowledge gaps, are seen as important approachesto advance monitoring. Including all relevant chemical contaminants in more holistic “chemical status”assessment, using effect-based trigger values to address priority mixtures of chemicals, to better consider historicalburdens accumulated in sediments and to use models to fill data gaps are recommended for a consistent assessmentof contamination. Solution-oriented m

Ion specific effects: decoupling ion-ion and ion-water interactions

PubMed Central

Song, Jinsuk; Kang, Tae Hui; Kim, Mahn Won; Han, Songi

2015-01-01

Ion-specific effects in aqueous solution, known as the Hofmeister effect is prevalent in diverse systems ranging from pure ionic to complex protein solutions. The objective of this paper is to explicitly demonstrate how complex ion-ion and ion-water interactions manifest themselves in the Hofmeister effects, based on a series of recent experimental observation. These effects are not considered in the classical description of ion effects, such as the Deryaguin-Landau-Verwey-Overbeek (DLVO) theory that, likely for that reason, fail to describe the origin of the phenomenological Hofmeister effect. However, given that models considering the basic forces of electrostatic and van der Waals interactions can offer rationalization for the core experimental observations, a universal interaction model stands a chance to be developed. In this perspective, we separately derive the contribution from ion-ion electrostatic interaction and ion-water interaction from second harmonic generation (SHG) data at the air-ion solution interface, which yields an estimate of ion-water interactions in solution. Hofmeister ion effects observed on biological solutes in solution should be similarly influenced by contributions from ion-ion and ion-water interactions, where the same ion-water interaction parameters derived from SHG data at the air-ion solution interface could be applicable. A key experimental data set available from solution systems to probe ion-water interaction is the modulation of water diffusion dynamics near ions in bulk ion solution, as well as near biological liposome surfaces. It is obtained from Overhauser dynamic nuclear polarization (ODNP), a nuclear magnetic resonance (NMR) relaxometry technique. The surface water diffusivity is influenced by the contribution from ion-water interactions, both from localized surface charges and adsorbed ions, although the relative contribution of the former is larger on liposome surfaces. In this perspective, ion-water interaction energy values derived from experimental data for various ions are compared with theoretical values in the literature. Ultimately, quantifying ion-induced changes in surface energy for the purpose of developing valid theoretical models for ion-water interaction, will be critical to rationalizing the Hofmeister effect. PMID:25761273
Efficient sample preparation method based on solvent-assisted dispersive solid-phase extraction for the trace detection of butachlor in urine and waste water samples.

PubMed

Aladaghlo, Zolfaghar; Fakhari, Alireza; Behbahani, Mohammad

2016-10-01

In this work, an efficient sample preparation method termed solvent-assisted dispersive solid-phase extraction was applied. The used sample preparation method was based on the dispersion of the sorbent (benzophenone) into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre-concentration of the butachlor, the cloudy solution was centrifuged and butachlor in the sediment phase dissolved in ethanol and determined by gas chromatography with flame ionization detection. Under the optimized conditions (solution pH = 7.0, sorbent: benzophenone, 2%, disperser solvent: ethanol, 500 μL, centrifuged at 4000 rpm for 3 min), the method detection limit for butachlor was 2, 3 and 3 μg/L for distilled water, waste water, and urine sample, respectively. Furthermore, the preconcentration factor was 198.8, 175.0, and 174.2 in distilled water, waste water, and urine sample, respectively. Solvent-assisted dispersive solid-phase extraction was successfully used for the trace monitoring of butachlor in urine and waste water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Hydration patterns and salting effects in sodium chloride solution.

PubMed

Li, Weifeng; Mu, Yuguang

2011-10-07

The salting effects of 2M sodium chloride electrolyte are studied based on a series of model solutes with properties ranging from hydrophobic to hydrophilic. Generally, hydrophobic solutes will be salted out and hydrophilic solutes will be salted in by NaCl solution. The solvation free energy changes are highly correlated with Kirkwood-Buff integrals. The underlying mechanism resorts to the preferential binding of ions and water to solutes. Our results demonstrate that the salting effect not only depends on the salt's position in Hofmeister series, but also on the solutes' specifics. Taking the hydration free energies of solutes and ions as independent variables, a schematic diagram of salting effects is suggested. The resolved multifaceted salting effects rely on the sensitive balance of the tripartite interaction among solutes, ions, and water. © 2011 American Institute of Physics
Sampling Odor Substances by Mist-Cyclone System

NASA Astrophysics Data System (ADS)

Matsubara, Osamu; Jiang, Zhiheng; Toyama, Shigeki

2009-05-01

Many techniques have been developed to measure odor substances. However most of those methods are based on using aquatic solutions(1),(2). Many odor substances specifically at low density situation, are difficult to dissolve into water. To absorb odor substances and obtain highest concentration solutions are key problems for olfactory systems. By blowing odor substances contained air mixture through mist of water and then separating the liquid from two-phases fluid with a cyclone unit a high concentration solution was obtained.
Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations

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

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y.

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. In such simulations we often perform them at elevated temperaturesmore » to artificially “correct” for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. In order to address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na +, K +, and Cl - ions. We show that simulations at 390–400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. These results suggest that an elevated temperature around 390–400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.« less
Structure and dynamics of aqueous solutions from PBE-based first-principles molecular dynamics simulations

DOE PAGES

Pham, Tuan Anh; Ogitsu, Tadashi; Lau, Edmond Y.; ...

2016-10-17

Establishing an accurate and predictive computational framework for the description of complex aqueous solutions is an ongoing challenge for density functional theory based first-principles molecular dynamics (FPMD) simulations. In this context, important advances have been made in recent years, including the development of sophisticated exchange-correlation functionals. On the other hand, simulations based on simple generalized gradient approximation (GGA) functionals remain an active field, particularly in the study of complex aqueous solutions due to a good balance between the accuracy, computational expense, and the applicability to a wide range of systems. In such simulations we often perform them at elevated temperaturesmore » to artificially “correct” for GGA inaccuracies in the description of liquid water; however, a detailed understanding of how the choice of temperature affects the structure and dynamics of other components, such as solvated ions, is largely unknown. In order to address this question, we carried out a series of FPMD simulations at temperatures ranging from 300 to 460 K for liquid water and three representative aqueous solutions containing solvated Na +, K +, and Cl - ions. We show that simulations at 390–400 K with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional yield water structure and dynamics in good agreement with experiments at ambient conditions. Simultaneously, this computational setup provides ion solvation structures and ion effects on water dynamics consistent with experiments. These results suggest that an elevated temperature around 390–400 K with the PBE functional can be used for the description of structural and dynamical properties of liquid water and complex solutions with solvated ions at ambient conditions.« less
Web-based Communication of Water Quality Issues and Potential Solution Exploration

EPA Science Inventory

Many United States water bodies are impaired, i.e., do not meet applicable water quality standards. Pollutants enter water bodies from point sources (PS) and non-point sources (NPS). Loadings from PS are regulated by the Clean Water Act and permits limit them. Loadings from NPS a...
Investigation of the dynamics of aqueous proline solutions using neutron scattering and molecular dynamics simulations.

PubMed

Malo de Molina, Paula; Alvarez, Fernando; Frick, Bernhard; Wildes, Andrew; Arbe, Arantxa; Colmenero, Juan

2017-10-18

We applied quasielastic neutron scattering (QENS) techniques to samples with two different contrasts (deuterated solute/hydrogenated solvent and the opposite label) to selectively study the component dynamics of proline/water solutions. Results on diluted and concentrated solutions (31 and 6 water molecules/proline molecule, respectively) were analyzed in terms of the susceptibility and considering a recently proposed model for water dynamics [Arbe et al., Phys. Rev. Lett., 2016, 117, 185501] which includes vibrations and the convolution of localized motions and diffusion. We found that proline molecules not only reduce the average diffusion coefficient of water but also extend the time/frequency range of the crossover region ('cage') between the vibrations and purely diffusive behavior. For the high proline concentration we also found experimental evidence of water heterogeneous dynamics and a distribution of diffusion coefficients. Complementary molecular dynamics simulations show that water molecules start to perform rotational diffusion when they escape the cage regime but before the purely diffusive behavior is established. The rotational diffusion regime is also retarded by the presence of proline molecules. On the other hand, a strong coupling between proline and water diffusive dynamics which persists with decreasing temperature is directly observed using QENS. Not only are the temperature dependences of the diffusion coefficients of both components the same, but their absolute values also approach each other with increasing proline concentration. We compared our results with those reported using other techniques, in particular using dielectric spectroscopy (DS). A simple approach based on molecular hydrodynamics and a molecular treatment of DS allows rationalizing the a priori puzzling inconsistency between QENS and dielectric results regarding the dynamic coupling of the two components. The interpretation proposed is based on general grounds and therefore should be applicable to other biomolecular solutions.
Hierarchical viscosity of aqueous solution of tilapia scale collagen investigated via dielectric spectroscopy between 500 MHz and 2.5 THz

PubMed Central

Kawamata, H.; Kuwaki, S.; Mishina, T.; Ikoma, T.; Tanaka, J.; Nozaki, R.

2017-01-01

Aqueous solutions of biomolecules such as proteins are very important model systems for understanding the functions of biomolecules in actual life processes because interactions between biomolecules and the surrounding water molecules are considered to be important determinants of biomolecules’ functions. Globule proteins have been extensively studied via dielectric spectroscopy; the results indicate three relaxation processes originating from fluctuations in the protein molecule, the bound water and the bulk water. However, the characteristics of aqueous solutions of collagens have rarely been investigated. In this work, based on broadband dielectric measurements between 500 MHz and 2.5 THz, we demonstrate that the high viscosity of a collagen aqueous solution is due to the network structure being constructed of rod-like collagen molecules surrounding free water molecules and that the water molecules are not responsible for the viscosity. We determine that the macroscopic viscosity is related to the mean lifetime of the collagen-collagen interactions supporting the networks and that the local viscosity of the water surrounded by the networks is governed by the viscosity of free water as in the bulk. This hierarchical structure in the dynamics of the aqueous solution of biomolecules has been revealed for the first time. PMID:28345664
Water's hydrogen bonds in the hydrophobic effect: a simple model.

PubMed

Xu, Huafeng; Dill, Ken A

2005-12-15

We propose a simple analytical model to account for water's hydrogen bonds in the hydrophobic effect. It is based on computing a mean-field partition function for a water molecule in the first solvation shell around a solute molecule. The model treats the orientational restrictions from hydrogen bonding, and utilizes quantities that can be obtained from bulk water simulations. We illustrate the principles in a 2-dimensional Mercedes-Benz-like model. Our model gives good predictions for the heat capacity of hydrophobic solvation, reproduces the solvation energies and entropies at different temperatures with only one fitting parameter, and accounts for the solute size dependence of the hydrophobic effect. Our model supports the view that water's hydrogen bonding propensity determines the temperature dependence of the hydrophobic effect. It explains the puzzling experimental observation that dissolving a nonpolar solute in hot water has positive entropy.
Optimization of a Nafion Membrane-Based System for Removal of Chloride and Fluoride from Lunar Regolith-Derived Water

NASA Technical Reports Server (NTRS)

Anthony, Stephen M.; Santiago-Maldonado, Edgardo; Captain, James G.; Pawate, Ashtamurthy S.; Kenis, Paul J. A.

2012-01-01

A long-term human presence in space will require self-sustaining systems capable of producing oxygen and potable water from extraterrestrial sources. Oxygen can be extracted from lunar regolith, and water contaminated with hydrochloric and hydrofluoric acids is produced as an intermediate in this process. We investigated the ability of Nafion proton exchange membranes to remove hydrochloric and hydrofluoric acids from water. The effect of membrane thickness, product stream flow rate, and acid solution temperature and concentration on water flux, acid rejection, and water and acid activity were studied. The conditions that maximized water transport and acid rejection while minimizing resource usage were determined by calculating a figure of merit. Water permeation is highest at high solution temperature and product stream flow rate across thin membranes, while chloride and fluoride permeation are lowest at low acid solution temperature and concentration across thin membranes. The figure of merit varies depending on the starting acid concentration; at low concentration, the figure of merit is highest across a thin membrane, while at high concentration, the figure of merit is highest at low solution temperature. In all cases, the figure of merit increases with increasing product stream flow rate.
The influence of carbon nanotubes on the properties of water solutions and fresh cement pastes

NASA Astrophysics Data System (ADS)

Leonavičius, D.; Pundienė, I.; Girskas, G.; Pranckevičienė, J.; Kligys, M.; Sinica, M.

2017-10-01

It is known, that the properties of cement-based materials can be significantly improved by addition of carbon nanotubes (CNTs). The dispersion of CNTs is an important process due to an extremely high specific surface area. This aspect is very relevant and is one of the main factors for the successful use of CNTs in cement-based materials. The influence of CNTs in different amounts (from 0 to 0.5 percent) on the pH values of water solutions and fresh cement pastes, and also on rheological properties, flow characteristics, setting time and EXO reaction of the fresh cement pastes was analyzed in this work. It was found that the increment of the amount of CNTs leads to decreased pH values of water solutions and fresh cement pastes, and also increases viscosity, setting times and EXO peak times of fresh cement pastes.
Binary ferrihydrite catalysts

DOEpatents

Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

1996-01-01

A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.
Solute transport through a pine-bark based substrate under saturated and unsaturated conditions

USDA-ARS?s Scientific Manuscript database

An understanding of how dissolved mineral nutrient ions (solutes) move through pine bark substrates during the application of irrigation water is vital to better understand nutrient transport and leaching from containerized crops during an irrigation event. However, current theories on solute transp...
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.
Study of different solutes for determination of neutron source strength based on the water bath

NASA Astrophysics Data System (ADS)

Khabaz, Rahim

2018-09-01

Time required for activation to saturation and background measurement is considered a limitation of strength determination of radionuclide neutron sources using manganese bath system (MBS). The objective of this research was to evaluate the other solutes based on water bath for presentation of the suitable replacement with MBS. With the aid Monte Carlo simulation, for three neutron sources, having different neutron spectra, immersed in six aqueous solutions, i.e., Na2SO4, VOSO4, MnSO4, Rh2(SO4)3, In2(SO4)3, I2O5, the correction factors in all nuclei of solutions for neutron losses with different process were obtained. The calculations results indicate that the Rh2(SO4)3 and VOSO4 are best options for replacing with MnSO4.
Experimental consideration of capillary chromatography based on tube radial distribution of ternary mixture carrier solvents under laminar flow conditions.

PubMed

Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2011-01-01

A capillary chromatography system has been developed based on the tube radial distribution of the carrier solvents using an open capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution. This tube radial distribution chromatography (TRDC) system works under laminar flow conditions. In this study, a phase diagram for the ternary mixture carrier solvents of water, acetonitrile, and ethyl acetate was constructed. The phase diagram that included a boundary curve between homogeneous and heterogeneous solutions was considered together with the component ratios of the solvents in the homogeneous carrier solutions required for the TRDC system. It was found that the TRDC system performed well with homogeneous solutions having component ratios of the solvents that were positioned near the homogeneous-heterogeneous solution boundary of the phase diagram. For preparing the carrier solutions of water-hydrophilic/hydrophobic organic solvents for the TRDC system, we used for the first time methanol, ethanol, 1,4-dioxane, and 1-propanol, instead of acetonitrile (hydrophilic organic solvent), as well as chloroform and 1-butanol, instead of ethyl acetate (hydrophobic organic solvent). The homogeneous ternary mixture carrier solutions were prepared near the homogeneous-heterogeneous solution boundary. Analyte mixtures of 2,6-naphthalenedisulfonic acid and 1-naphthol were separated with the TRDC system using these homogeneous ternary mixture carrier solutions. The pressure change in the capillary tube under laminar flow conditions might alter the carrier solution from homogeneous in the batch vessel to heterogeneous, thus affecting the tube radial distribution of the solvents in the capillary tube.
Energy-Water System Solutions | Energy Analysis | NREL

Science.gov Websites

simultaneously. Example Projects Energy, water, and renewable opportunities assessment at Bagram Air Force Base opportunity to plan integrated infrastructure. Example Projects Identification of critical water and campus-level opportunities. Example Projects Net Zero Energy-Water-Waste analysis for Fort Carson Net
Experimental testing and modeling analysis of solute mixing at water distribution pipe junctions.

PubMed

Shao, Yu; Jeffrey Yang, Y; Jiang, Lijie; Yu, Tingchao; Shen, Cheng

2014-06-01

Flow dynamics at a pipe junction controls particle trajectories, solute mixing and concentrations in downstream pipes. The effect can lead to different outcomes of water quality modeling and, hence, drinking water management in a distribution network. Here we have investigated solute mixing behavior in pipe junctions of five hydraulic types, for which flow distribution factors and analytical equations for network modeling are proposed. First, based on experiments, the degree of mixing at a cross is found to be a function of flow momentum ratio that defines a junction flow distribution pattern and the degree of departure from complete mixing. Corresponding analytical solutions are also validated using computational-fluid-dynamics (CFD) simulations. Second, the analytical mixing model is further extended to double-Tee junctions. Correspondingly the flow distribution factor is modified to account for hydraulic departure from a cross configuration. For a double-Tee(A) junction, CFD simulations show that the solute mixing depends on flow momentum ratio and connection pipe length, whereas the mixing at double-Tee(B) is well represented by two independent single-Tee junctions with a potential water stagnation zone in between. Notably, double-Tee junctions differ significantly from a cross in solute mixing and transport. However, it is noted that these pipe connections are widely, but incorrectly, simplified as cross junctions of assumed complete solute mixing in network skeletonization and water quality modeling. For the studied pipe junction types, analytical solutions are proposed to characterize the incomplete mixing and hence may allow better water quality simulation in a distribution network. Published by Elsevier Ltd.
Regional GRACE-based estimates of water mass variations over Australia: validation and interpretation

NASA Astrophysics Data System (ADS)

Seoane, L.; Ramillien, G.; Frappart, F.; Leblanc, M.

2013-04-01

Time series of regional 2°-by-2° GRACE solutions have been computed from 2003 to 2011 with a 10 day resolution by using an energy integral method over Australia [112° E 156° E; 44° S 10° S]. This approach uses the dynamical orbit analysis of GRACE Level 1 measurements, and specially accurate along-track K Band Range Rate (KBRR) residuals (1 μm s-1 level of error) to estimate the total water mass over continental regions. The advantages of regional solutions are a significant reduction of GRACE aliasing errors (i.e. north-south stripes) providing a more accurate estimation of water mass balance for hydrological applications. In this paper, the validation of these regional solutions over Australia is presented as well as their ability to describe water mass change as a reponse of climate forcings such as El Niño. Principal component analysis of GRACE-derived total water storage maps show spatial and temporal patterns that are consistent with independent datasets (e.g. rainfall, climate index and in-situ observations). Regional TWS show higher spatial correlations with in-situ water table measurements over Murray-Darling drainage basin (80-90%), and they offer a better localization of hydrological structures than classical GRACE global solutions (i.e. Level 2 GRGS products and 400 km ICA solutions as a linear combination of GFZ, CSR and JPL GRACE solutions).

No Solutions: Resisting Certainty in Water Supply Management

NASA Astrophysics Data System (ADS)

Cockerill, K.; Armstrong, M.; Richter, J.; Okie, J. G.

2017-12-01

Although most scholars and water managers implicitly understand that managing water resources is an ongoing need, both popular and academic literature routinely use the words `solution' and `solve' in discussing water management concerns. The word `solution' reflects a quest for certainty, stability, permanence. A focus on `solving' creates a simplistic expectation that some person or institution is responsible for implementing a solution and that once `solved' the issue no longer requires attention. The reality, however, is water management is a wicked problem, meaning it is amorphous, involves multiple definitions, is embedded in complex systems, and hence is intractable. By definition, wicked problems defy solution. Our interdisciplinary project integrates research from across a broad spectrum of biological, physical, and social sciences. We find that framing a problem in terms of `solving' affects how people think, feel, behave toward the problem. Further, our work suggests that the prevalence of solution- based language has simultaneously generated expectations that science / scientists can predict and control biophysical systems and that science is not to be trusted because it has failed to deliver on previous promises to permanently `solve' events like floods or droughts. Hydrologic systems, are, of course highly uncertain. Hence, reiterating a simplistic insistence on `solving' water management concerns may result in decreased public attention to or support for more complex policy discussions that could provide long-term management strategies. Using the language of `solutions' with expectations of certainty sets hydrologic researchers and water managers up to fail. Managing water is a social responsibility and it will require consistent attention in the future, just as it has throughout human history. Scientists have a key role to play in explaining how various hydrologic systems function, but they should not be expected to `solve' pressing water management needs. Rather, reconsidering the language used to frame water management concerns can help us recognize our own culpability in creating water problems and our responsibility in continuously managing this most essential resource.
The Solutions Data Base Component of the Water Pollution Abatement Subsystem (WPAS) of the Pollution Abatement Management System. (PAMS).

DTIC Science & Technology

1981-04-01

Facilities EngineerATTN: DAEN-MPC Fitzs ;mons Amy Medical Center ATTN: DAEN-PE Army Instl. and Major Activities (CONuS; waiter Reed Army Medical center ATTN...S)St. Paul Fort Sheridan 21st Support ComandTulsa Fort Stewart4 Vicksburg Fort Wainmright AN: AREA (5) Walls Walla Vancouver Bks. Wilmington US Am...ABG/DEEE Patrick AFB, FL 32925 ATTN: XRQ ’ C Bandy, John T. The Solutions Data Base component of the Water Pollution Abatement Subsystem (WPAS) of the
Bioinspired Surface Treatments for Improved Decontamination: Silicate-Based Slippery Liquid-Infused Porous Surfaces (SLIPS)

DTIC Science & Technology

2017-07-20

methyl salicylate, dimethyl methylphosphate, and diisopropyl fluorophosphates following treatment of contaminated surfaces with a soapy water solution...and diisopropyl fluorophosphate following treatment of contaminated surfaces with a soapy water solution is reported along with droplet diffusion on...SURFACES (SLIPS) INTRODUCTION The DoD Chemical and Biological Defense Program (CBDP) seeks to provide protection of forces in a contaminated
Amount of leachant and water absorption levels of wood treated with borates and water repellents.

PubMed

Baysal, Ergun; Sonmez, Abdullah; Colak, Mehmet; Toker, Hilmi

2006-12-01

Wood protection efficacy of borates against biological agents, flame retardancy, and suitability to the environment is well known. Since borates can be applied to timber as water based solutions, they are preferred economically as well. Even though they are highly mobile in wood, boron compounds are widely used in timber preservation. Borates migrate in liquid and increase the hygroscopicity of wood in damp conditions. This study deals with the physical restriction of water access in wood by impregnating water repellent agents into wood to limit amount of leachant and water absorption levels of wood after boron treatment. Borates were incorporated with polyethylene glycol-400 (PEG-400) their bulking effect in wood was considered. Results indicated that the amount of leachates from wood treated with borates in PEG-400 was remarkably higher compared to those of wood treated with the aqueous solutions of borates. Water absorption (WA) levels of wood treated with aqueous solutions of borates were higher than those of their treated samples with the solutions in PEG-400. Secondary treatments of wood with the water repellent (WR) chemicals following borate impregnation reduced the leaching of chemicals from wood in water and also WA of the specimens were less than those of the wood treated with only borates from aqueous and PEG solutions. Styrene (St) was the most effective monomer among the other agents used in terms of immobility effect on borates and WA.
Influence of Aromatic Molecules on the Structure and Spectroscopy of Water Clusters

NASA Astrophysics Data System (ADS)

Tabor, Daniel P.; Sibert, Edwin; Walsh, Patrick S.; Zwier, Timothy S.

2016-06-01

Isomer-specific resonant ion-dip infrared spectra are presented for benzene-(water)_n, 1-2-diphenoxyethane-(water)_n, and tricyclophane-(water)_n clusters. The IR spectra are modeled with a local mode Hamiltonian that was originally formulated for the analysis of benzene-(water)_n clusters with up to seven waters. The model accounts for stretch-bend Fermi coupling, which can complicate the IR spectra in the 3150-3300 cm-1 region. When the water clusters interact with each of the solutes, the hydrogen bond lengths between the water molecules change in a characteristic way, reflecting the strength of the solute-water interaction. These structural effects are also reflected spectroscopically in the shifts of the local mode OH stretch frequencies. When diphenoxyethane is the solute, the water clusters distort more significantly than when bound to benzene. Tricyclophane's structure provides an aromatic-rich binding pocket for the water clusters. The local mode model is used to extract Hamiltonians for individual water molecules. These monomer Hamiltonians divide into groups based on their local H-bonding architecture, allowing for further classification of the wide variety of water environments encountered in this study.
Concentration Dependences of the Surface Tension and Density of Solutions of Acetone-Ethanol-Water Systems at 293 K

NASA Astrophysics Data System (ADS)

Dadashev, R. Kh.; Dzhambulatov, R. S.; Mezhidov, V. Kh.; Elimkhanov, D. Z.

2018-05-01

Concentration dependences of the surface tension and density of solutions of three-component acetone-ethanol-water systems and the bounding binary systems at 273 K are studied. The molar volume, adsorption, and composition of surface layers are calculated. Experimental data and calculations show that three-component solutions are close to ideal ones. The surface tensions of these solutions are calculated using semi-empirical and theoretical equations. Theoretical equations qualitatively convey the concentration dependence of surface tension. A semi-empirical method based on the Köhler equation allows us to predict the concentration dependence of surface tension within the experimental error.
Boron sorption from aqueous solution by hydrotalcite and its preliminary application in geothermal water deboronation.

PubMed

Guo, Qinghai; Zhang, Yin; Cao, Yaowu; Wang, Yanxin; Yan, Weide

2013-11-01

Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing boron as a major undesirable element. The kinetics process of boron sorption by uncalcined hydrotalcite is controlled by the diffusion of boron from bulk solution to sorbent-solution boundary film and its exchange with interlayer chloride of hydrotalcite, whereas the removal rate of boron by calcined hydrotalcite rests with the restoration process of its layered structure. The results of isotherm sorption experiments reveal that calcined hydrotalcite generally has much stronger ability to lower solution boron concentration than uncalcined hydrotalcite. The combination of adsorption of boron on the residue of MgO-Al2O3 solid solution and intercalation of boron into the reconstructed hydrotalcite structure due to "structural memory effect" is the basic mechanism based on which the greater boron removal by calcined hydrotalcite was achieved. As 15 geothermal water samples were used to test the deboronation ability of calcined hydrotalcite at 65 °C, much lower boron removal efficiencies were observed. The competitive sorption of the other anions in geothermal water, such as HCO3-, SO4(2-), and F-, is the reason why calcined hydrotalcite could not remove boron from geothermal water as effectively as from pure boron solution. However, boron removal percents ranging from 89.3 to 99.0% could be obtained if 50 times of sorbent were added to the geothermal water samples. Calcined hydrotalcite is a good candidate for deboronation of geothermal water.
Incorporation of the TIP4P water model into a continuum solvent for computing solvation free energy

NASA Astrophysics Data System (ADS)

Yang, Pei-Kun

2014-10-01

The continuum solvent model is one of the commonly used strategies to compute solvation free energy especially for large-scale conformational transitions such as protein folding or to calculate the binding affinity of protein-protein/ligand interactions. However, the dielectric polarization for computing solvation free energy from the continuum solvent is different than that obtained from molecular dynamic simulations. To mimic the dielectric polarization surrounding a solute in molecular dynamic simulations, the first-shell water molecules was modeled using a charge distribution of TIP4P in a hard sphere; the time-averaged charge distribution from the first-shell water molecules were estimated based on the coordination number of the solute, and the orientation distribution of the first-shell waters and the intermediate water molecules were treated as that of a bulk solvent. Based on this strategy, an equation describing the solvation free energy of ions was derived.
Towards the review of the European Union Water Framework Directive: Recommendations for more efficient assessment and management of chemical contamination in European surface water resources.

PubMed

Brack, Werner; Dulio, Valeria; Ågerstrand, Marlene; Allan, Ian; Altenburger, Rolf; Brinkmann, Markus; Bunke, Dirk; Burgess, Robert M; Cousins, Ian; Escher, Beate I; Hernández, Félix J; Hewitt, L Mark; Hilscherová, Klára; Hollender, Juliane; Hollert, Henner; Kase, Robert; Klauer, Bernd; Lindim, Claudia; Herráez, David López; Miège, Cécil; Munthe, John; O'Toole, Simon; Posthuma, Leo; Rüdel, Heinz; Schäfer, Ralf B; Sengl, Manfred; Smedes, Foppe; van de Meent, Dik; van den Brink, Paul J; van Gils, Jos; van Wezel, Annemarie P; Vethaak, A Dick; Vermeirssen, Etienne; von der Ohe, Peter C; Vrana, Branislav

2017-01-15

Water is a vital resource for natural ecosystems and human life, and assuring a high quality of water and protecting it from chemical contamination is a major societal goal in the European Union. The Water Framework Directive (WFD) and its daughter directives are the major body of legislation for the protection and sustainable use of European freshwater resources. The practical implementation of the WFD with regard to chemical pollution has faced some challenges. In support of the upcoming WFD review in 2019 the research project SOLUTIONS and the European monitoring network NORMAN has analyzed these challenges, evaluated the state-of-the-art of the science and suggested possible solutions. We give 10 recommendations to improve monitoring and to strengthen comprehensive prioritization, to foster consistent assessment and to support solution-oriented management of surface waters. The integration of effect-based tools, the application of passive sampling for bioaccumulative chemicals and an integrated strategy for prioritization of contaminants, accounting for knowledge gaps, are seen as important approaches to advance monitoring. Including all relevant chemical contaminants in more holistic "chemical status" assessment, using effect-based trigger values to address priority mixtures of chemicals, to better consider historical burdens accumulated in sediments and to use models to fill data gaps are recommended for a consistent assessment of contamination. Solution-oriented management should apply a tiered approach in investigative monitoring to identify toxicity drivers, strengthen consistent legislative frameworks and apply solutions-oriented approaches that explore risk reduction scenarios before and along with risk assessment. Copyright © 2016. Published by Elsevier B.V.
Prediction of unsaturated flow and water backfill during infiltration in layered soils

NASA Astrophysics Data System (ADS)

Cui, Guotao; Zhu, Jianting

2018-02-01

We develop a new analytical infiltration model to determine water flow dynamics around layer interfaces during infiltration process in layered soils. The model mainly involves the analytical solutions to quadratic equations to determine the flux rates around the interfaces. Active water content profile behind the wetting front is developed based on the solution of steady state flow to dynamically update active parameters in sharp wetting front infiltration equations and to predict unsaturated flow in coarse layers before the front reaches an impeding fine layer. The effect of water backfill to saturate the coarse layers after the wetting front encounters the impeding fine layer is analytically expressed based on the active water content profiles. Comparison to the numerical solutions of the Richards equation shows that the new model can well capture water dynamics in relation to the arrangement of soil layers. The steady state active water content profile can be used to predict the saturation state of all layers when the wetting front first passes through these layers during the unsteady infiltration process. Water backfill effect may occur when the unsaturated wetting front encounters a fine layer underlying a coarse layer. Sensitivity analysis shows that saturated hydraulic conductivity is the parameter dictating the occurrence of unsaturated flow and water backfill and can be used to represent the coarseness of soil layers. Water backfill effect occurs in coarse layers between upper and lower fine layers when the lower layer is not significantly coarser than the upper layer.
Analytical optimization of demand management strategies across all urban water use sectors

NASA Astrophysics Data System (ADS)

Friedman, Kenneth; Heaney, James P.; Morales, Miguel; Palenchar, John

2014-07-01

An effective urban water demand management program can greatly influence both peak and average demand and therefore long-term water supply and infrastructure planning. Although a theoretical framework for evaluating residential indoor demand management has been well established, little has been done to evaluate other water use sectors such as residential irrigation in a compatible manner for integrating these results into an overall solution. This paper presents a systematic procedure to evaluate the optimal blend of single family residential irrigation demand management strategies to achieve a specified goal based on performance functions derived from parcel level tax assessor's data linked to customer level monthly water billing data. This framework is then generalized to apply to any urban water sector, as exponential functions can be fit to all resulting cumulative water savings functions. Two alternative formulations are presented: maximize net benefits, or minimize total costs subject to satisfying a target water savings. Explicit analytical solutions are presented for both formulations based on appropriate exponential best fits of performance functions. A direct result of this solution is the dual variable which represents the marginal cost of water saved at a specified target water savings goal. A case study of 16,303 single family irrigators in Gainesville Regional Utilities utilizing high quality tax assessor and monthly billing data along with parcel level GIS data provide an illustrative example of these techniques. Spatial clustering of targeted homes can be easily performed in GIS to identify priority demand management areas.
Solution-Based Electro-Orientation Spectroscopy (EOS) for Contactless Measurement of Semiconductor Nanowires

NASA Astrophysics Data System (ADS)

Yuan, Wuhan; Mohabir, Amar; Tutuncuoglu, Gozde; Filler, Michael; Feldman, Leonard; Shan, Jerry

2017-11-01

Solution-based, contactless methods for determining the electrical conductivity of nanowires and nanotubes have unique advantages over conventional techniques in terms of high throughput and compatibility with further solution-based processing and assembly methods. Here, we describe the solution-based electro-orientation spectroscopy (EOS) method, in which nanowire conductivity is measured from the AC-electric-field-induced alignment rate of the nanowire in a suspending fluid. The particle conductivity is determined from the measured crossover frequency between conductivity-dominated, low-frequency alignment to the permittivity-dominated, high-frequency regime. We discuss the extension of the EOS measurement range by an order-of-magnitude, taking advantage of the high dielectric constant of deionized water. With water and other fluids, we demonstrate that EOS can quantitatively characterize the electrical conductivities of nanowires over a 7-order-of-magnitude range, 10-5 to 102 S/m. We highlight the efficiency and utility of EOS for nanomaterial characterization by statistically characterizing the variability of semiconductor nanowires of the same nominal composition, and studying the connection between synthesis parameters and properties. NSF CBET-1604931.
Local Water Policy Innovation: A Road Map for Community Based Stormwater Solutions

EPA Pesticide Factsheets

This American Rivers report argues that local governments are in the best position to manage the water quality impacts of urbanization. The report describes 10 measures that local governments can take to minimize the degradation of water resources.
Polymer-coated nanoparticles: Carrier platforms for hydrophobic water- and air-sensitive metallo-organic compounds.

PubMed

Valdeperez, Daniel; Wang, Tianqiang; Eußner, Jens P; Weinert, Bastian; Hao, Jianyuan; Parak, Wolfgang J; Dehnen, Stefanie; Pelaz, Beatriz

2017-03-01

Many of the relevant compounds for anticancer therapy are metal-based compounds (metallodrugs), being platinum-based drugs such as cisplatin, carboplatin (Paraplatin ® ), and oxaliplatin (Eloxatin ® ) the most widely used. Despite this, their application is limited by issues such as cell-acquired platinum resistance and manifold side effects following systemic delivery. Thus, the development of new metal-based compounds is highly needed. The catalytic properties of a variety of metal-based compounds are nowadays very well known, which opens new opportunities to take advantage of them inside living cells or organisms. However, many of these compounds are hydrophobic and thus not soluble in aqueous solution, as they lack stability against water or oxygen presence. Thus, versatile platforms capable of enhancing the features of these compounds in aqueous solutions are of importance in the development of new drugs. Surface engineered nanoparticles may render metallodrugs with good colloidal stability in water and in complex media containing high salt concentration and/or proteins. Herein, polymer coated nanoparticles are proposed as a platform to link insoluble and water/oxygen sensitive drugs. The linkage of insoluble and oxygen sensitive tin clusters to nanoparticles is presented, aiming to enhance both, the solubility and the stability of these compounds in water, which may be an alternative approach in the development of metal-based drugs. The formation of the cluster-nanoparticle system was confirmed via inductively coupled plasma mass spectrometry experiments. The catalytic activity and the stability of the cluster in water were studied through the reduction of methylene blue. Results demonstrate that in fact the tin clusters could be transferred into aqueous solution and retained their catalytic activity. Copyright © 2016 Elsevier Ltd. All rights reserved.
Binary ferrihydrite catalysts

DOEpatents

Huffman, G.P.; Zhao, J.; Feng, Z.

1996-12-03

A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.
Experimental Investigations of the Weathering of Suspended Sediment by Alpine Glacial Meltwater

NASA Astrophysics Data System (ADS)

Brown, Giles H.; Tranter, M.; Sharp, M. J.

1996-04-01

The magnitude and processes of solute acquisition by dilute meltwater in contact with suspended sediment in the channelized component of the hydroglacial system have been investigated through a suite of controlled laboratory experiments. Constrained by field data from Haut Glacier d'Arolla, Valais, Switzerland the effects of the water to rock ratio, particle size, crushing, repeated wetting and the availability of protons on the rate of solute acquisition are demonstrated. These free-drift experiments suggest that the rock flour is extremely geochemically reactive and that dilute quickflow waters are certain to acquire solute from suspended sediment. These data have important implications for hydrological interpretations based on the solute content of glacial meltwater, mixing model calculations, geochemical denudation rates and solute provenance studies.
Providing the physical basis of SCS curve number method and its proportionality relationship from Richards' equation

NASA Astrophysics Data System (ADS)

Hooshyar, M.; Wang, D.

2016-12-01

The empirical proportionality relationship, which indicates that the ratio of cumulative surface runoff and infiltration to their corresponding potentials are equal, is the basis of the extensively used Soil Conservation Service Curve Number (SCS-CN) method. The objective of this paper is to provide the physical basis of the SCS-CN method and its proportionality hypothesis from the infiltration excess runoff generation perspective. To achieve this purpose, an analytical solution of Richards' equation is derived for ponded infiltration in shallow water table environment under the following boundary conditions: 1) the soil is saturated at the land surface; and 2) there is a no-flux boundary which moves downward. The solution is established based on the assumptions of negligible gravitational effect, constant soil water diffusivity, and hydrostatic soil moisture profile between the no-flux boundary and water table. Based on the derived analytical solution, the proportionality hypothesis is a reasonable approximation for rainfall partitioning at the early stage of ponded infiltration in areas with a shallow water table for coarse textured soils.
Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

NASA Technical Reports Server (NTRS)

Defalco, Francis G. (Inventor); Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor)

2017-01-01

A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, water, or a water-based lubricant. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.
Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

USGS Publications Warehouse

Chiou, C.T.; Schmedding, D.W.; Manes, M.

2005-01-01

A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.
Shallow water equations: viscous solutions and inviscid limit

NASA Astrophysics Data System (ADS)

Chen, Gui-Qiang; Perepelitsa, Mikhail

2012-12-01

We establish the inviscid limit of the viscous shallow water equations to the Saint-Venant system. For the viscous equations, the viscosity terms are more degenerate when the shallow water is close to the bottom, in comparison with the classical Navier-Stokes equations for barotropic gases; thus, the analysis in our earlier work for the classical Navier-Stokes equations does not apply directly, which require new estimates to deal with the additional degeneracy. We first introduce a notion of entropy solutions to the viscous shallow water equations and develop an approach to establish the global existence of such solutions and their uniform energy-type estimates with respect to the viscosity coefficient. These uniform estimates yield the existence of measure-valued solutions to the Saint-Venant system generated by the viscous solutions. Based on the uniform energy-type estimates and the features of the Saint-Venant system, we further establish that the entropy dissipation measures of the viscous solutions for weak entropy-entropy flux pairs, generated by compactly supported C 2 test-functions, are confined in a compact set in H -1, which yields that the measure-valued solutions are confined by the Tartar-Murat commutator relation. Then, the reduction theorem established in Chen and Perepelitsa [5] for the measure-valued solutions with unbounded support leads to the convergence of the viscous solutions to a finite-energy entropy solution of the Saint-Venant system with finite-energy initial data, which is relative with respect to the different end-states of the bottom topography of the shallow water at infinity. The analysis also applies to the inviscid limit problem for the Saint-Venant system in the presence of friction.

Studies on the treatment of urine by the biological purification-UV photocatalytic oxidation

NASA Astrophysics Data System (ADS)

Liu, Ch. Ch; Liu, R. D.; Liu, X. S.; Chen, M.; Bian, Z. L.; Hu, J. Ch.

The water-consuming amount in a long-term astro-navigation is large In order to reduce the burden of water supply from Earth ground the space station needs to resolve the problems of water supply For this reason the recovery and regeneration of urine solution of spacemen and its utilization possess a key importance Many investigations on this aspect have been reported Our research based on biological absorption-purification-UV photocatalytic oxidation techniques with a relevant treating equipment that for a comprehensive treatment to fresh urine of spacemen has been created In this equipment the urine solution was used as the nutrient solution for the biological parts in ecological life ensurant system after absorbing the nutrient it was decomposed metabolized and purified in some distance and created a favorable condition for the follow-up oxidation treatment by UV-Photocatalytic Oxidation After these two processes the treated urine solution reached the GB5749-85 standard of water quality
Advanced material and approach for metal ions removal from aqueous solutions

PubMed Central

Turhanen, Petri A.; Vepsäläinen, Jouko J.; Peräniemi, Sirpa

2015-01-01

A Novel approach to remove metals from aqueous solutions has been developed. The method is based on a resin free, solid, non-toxic, microcrystalline bisphosphonate material, which has very low solubility in water (59 mg/l to ion free Milli-Q water and 13 mg/l to 3.5% NaCl solution). The material has been produced almost quantitatively on a 1 kg scale (it has been prepared also on a pilot scale, ca. 7 kg) and tested successfully for its ability to collect metal cations from different sources, such as ground water and mining process waters. Not only was this material highly efficient at collecting several metal ions out of solution it also proved to be regenerable and reusable over a number of adsorption/desorption, which is crucial for environmental friendliness. This material has several advantages compared to the currently used approaches, such as no need for any precipitation step. PMID:25758924
Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

PubMed

Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

2018-02-07

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.
A natural driven membrane process for brackish and wastewater treatment: photovoltaic powered ED and FO hybrid system.

PubMed

Zhang, Yang; Pinoy, Luc; Meesschaert, Boudewijn; Van der Bruggen, Bart

2013-09-17

In isolated locations, remote areas, or islands, potable water is precious because of the lack of drinking water treatment facilities and energy supply. Thus, a robust and reliable water treatment system based on natural energy is needed to reuse wastewater or to desalinate groundwater/seawater for provision of drinking water. In this work, a hybrid membrane system combining electrodialysis (ED) and forward osmosis (FO), driven by renewable energy (solar energy), denoted as EDFORD (ED-FO Renewable energy Desalination), is proposed to produce high-quality water (potable) from secondary wastewater effluent or brackish water. In this hybrid membrane system, feedwater (secondary wastewater effluent or synthetic brackish water) was drawn to the FO draw solution while the organic and inorganic substances (ions, compounds, colloids and particles) were rejected. The diluted draw solution was then pumped to the solar energy driven ED. In the ED unit, the diluted draw solution was desalted and high-quality water was produced; the concentrate was recycled to the FO unit and reused as the draw solution. Results show that the water produced from this system contains a low concentration of total organic carbon (TOC), carbonate, and cations derived from the feedwater; had a low conductivity; and meets potable water standards. The water production cost considering the investment for membranes and solar panel is 3.32 to 4.92 EUR m(-3) (for 300 days of production per year) for a small size potable water production system.
DOE Office of Scientific and Technical Information (OSTI.GOV)

HEDENGREN, D.C.

Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia inmore » water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the flammability of vapor space gas mixtures in waste tanks.« less
Gas-liquid transfer data used to analyze hydrophobic hydration and find the nature of the Kauzmann-Tanford hydrophobic factor.

PubMed

Baldwin, Robert L

2012-05-08

Hydrophobic free energy for protein folding is currently measured by liquid-liquid transfer, based on an analogy between the folding process and the transfer of a nonpolar solute from water into a reference solvent. The second part of the analogy (transfer into a nonaqueous solvent) is dubious and has been justified by arguing that transfer out of water probably contributes the major part of the free energy change. This assumption is wrong: transfer out of water contributes no more than half the total, often less. Liquid-liquid transfer of the solute from water to liquid alkane is written here as the sum of 2 gas-liquid transfers: (i) out of water into vapor, and (ii) from vapor into liquid alkane. Both gas-liquid transfers have known free energy values for several alkane solutes. The comparable values of the two different transfer reactions are explained by the values, determined in 1991 for three alkane solutes, of the cavity work and the solute-solvent interaction energy. The transfer free energy is the difference between the positive cavity work and the negative solute-solvent interaction energy. The interaction energy has similar values in water and liquid alkane that are intermediate in magnitude between the cavity work in water and in liquid alkane. These properties explain why the transfer free energy has comparable values (with opposite signs) in the two transfers. The current hydrophobic free energy is puzzling and poorly defined and needs a new definition and method of measurement.
Gas-liquid transfer data used to analyze hydrophobic hydration and find the nature of the Kauzmann-Tanford hydrophobic factor

PubMed Central

Baldwin, Robert L.

2012-01-01

Hydrophobic free energy for protein folding is currently measured by liquid-liquid transfer, based on an analogy between the folding process and the transfer of a nonpolar solute from water into a reference solvent. The second part of the analogy (transfer into a nonaqueous solvent) is dubious and has been justified by arguing that transfer out of water probably contributes the major part of the free energy change. This assumption is wrong: transfer out of water contributes no more than half the total, often less. Liquid-liquid transfer of the solute from water to liquid alkane is written here as the sum of 2 gas-liquid transfers: (i) out of water into vapor, and (ii) from vapor into liquid alkane. Both gas-liquid transfers have known free energy values for several alkane solutes. The comparable values of the two different transfer reactions are explained by the values, determined in 1991 for three alkane solutes, of the cavity work and the solute-solvent interaction energy. The transfer free energy is the difference between the positive cavity work and the negative solute-solvent interaction energy. The interaction energy has similar values in water and liquid alkane that are intermediate in magnitude between the cavity work in water and in liquid alkane. These properties explain why the transfer free energy has comparable values (with opposite signs) in the two transfers. The current hydrophobic free energy is puzzling and poorly defined and needs a new definition and method of measurement. PMID:22529345
Forward Osmosis Brine Drying

NASA Technical Reports Server (NTRS)

Flynn, Michael; Shaw, Hali; Hyde, Deirdre; Beeler, David; Parodi, Jurek

2015-01-01

The Forward Osmosis Brine Drying (FOBD) system is based on a technique called forward osmosis (FO). FO is a membrane-based process where the osmotic potential between brine and a salt solution is equalized by the movement of water from the brine to the salt solution. The FOBD system is composed of two main elements, the FO bag and the salt regeneration system. This paper discusses the results of testing of the FO bag to determine the maximum water recovery ratio that can be attained using this technology. Testing demonstrated that the FO bag is capable of achieving a maximum brine water recovery ratio of the brine of 95%. The equivalent system mass was calculated to be 95 kg for a feed similar to the concentrated brine generated on the International Space Station and 86 kg for an Exploration brine. The results have indicated that the FOBD can process all the brine for a one year mission for between 11% to 10% mass required to bring the water needed to make up for water lost in the brine if not recycled. The FOBD saves 685 kg and when treating the International Space Station brine and it saves 829 kg when treating the Exploration brine. It was also demonstrated that saturated salt solutions achieve a higher water recovery ratios than solids salts do and that lithium chloride achieved a higher water recovery ratio than sodium chloride.
Nanofibrous membrane-based absorption refrigeration system

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

Isfahani, RN; Sampath, K; Moghaddam, S

2013-12-01

This paper presents a study on the efficacy of highly porous nanofibrous membranes for application in membrane-based absorbers and desorbers. Permeability studies showed that membranes with a pore size greater than about one micron have a sufficient permeability for application in the absorber heat exchanger. Membranes with smaller pores were found to be adequate for the desorber heat exchanger. The membranes were implemented in experimental membrane-based absorber and desorber modules and successfully tested. Parametric studies were conducted on both absorber and desorber processes. Studies on the absorption process were focused on the effects of water vapor pressure, cooling water temperature,more » and the solution velocity on the absorption rate. Desorption studies were conducted on the effects of wall temperature, vapor and solution pressures, and the solution velocity on the desorption rate. Significantly higher absorption and desorption rates than in the falling film absorbers and desorbers were achieved. Published by Elsevier Ltd.« less
Convective transport resistance in the vitreous humor

NASA Astrophysics Data System (ADS)

Penkova, Anita; Sadhal, Satwindar; Ratanakijsuntorn, Komsan; Moats, Rex; Tang, Yang; Hughes, Patrick; Robinson, Michael; Lee, Susan

2012-11-01

It has been established by MRI visualization experiments that the convection of nanoparticles and large molecules with high rate of water flow in the vitreous humor will experience resistance, depending on the respective permeabilities of the injected solute. A set of experiments conducted with Gd-DTPA (Magnevist, Bayer AG, Leverkusen, Germany) and 30 nm gadolinium-based particles (Gado CELLTrackTM, Biopal, Worcester, MA) as MRI contrast agents showed that the degree of convective transport in this Darcy-type porous medium varies between the two solutes. These experiments consisted of injecting a mixture of the two (a 30 μl solution of 2% Magnevist and 1% nanoparticles) at the middle of the vitreous of an ex vivo whole bovine eye and subjecting the vitreous to water flow rate of 100 μl/min. The water (0.9% saline solution) was injected at the top of the eye, and was allowed to drain through small slits cut at the bottom of the eyeball. After 50 minutes of pumping, MRI images showed that the water flow carried the Gd-DTPA farther than the nanoparticles, even though the two solutes, being mixed, were subjected to the same convective flow conditions. We find that the convected solute lags the water flow, depending on the solute permeability. The usual convection term needs to be adjusted to allow for the filtration effect on the larger particles in the form (1- σ) u . ∇ c with important implications for the modeling of such systems.
Nature-based solutions for hydro-meteorological risk reduction and nutrient removal in the Nordic and Arctic regions

NASA Astrophysics Data System (ADS)

Bring, Arvid; Kalantari, Zahra

2017-04-01

Natural ecological functions provide essential and fundamental benefits to mankind, but can also be actively employed in nature-based solutions to specific challenges in society. For example, water-related ecosystem services have a role in such societal benefits as flood protection, erosion control, and excess nutrient removal. Ecosystem services may be produced and consumed in different locations, and research has recently attempted to formalize this discrepancy in identifying service providing areas (SPAs), service benefitting areas (SBAs), and service connecting areas (SCAs). However, in terms of water-related services, there is a lack of formal evaluation of how SPAs, SBAs, and SCAs are related to hydrological measures such as discharge, flood recurrence, excess nutrient removal, etc. We seek to map SPAs, SBAs and SCAs for a number of key ecosystem services in the Nordic and Arctic region though established ecological definitions (typically, based on land use) and evaluate the findings alongside metrics of hydrological connectivity (river networks), provisioning areas (runoff generating areas), and benefitting areas (river stretches where water flow is moderated). We make use of extensive GIS analysis using both high-resolution land cover data and river network maps. In the end, the results are expected to contribute to identifying how water-related ecosystem services can be employed as nature-based solutions for hydro-meteorological risk reduction and nutrient removal in a changing climate in the Nordic and Arctic regions.
An isotherm-based thermodynamic model of multicomponent aqueous solutions, applicable over the entire concentration range.

PubMed

Dutcher, Cari S; Ge, Xinlei; Wexler, Anthony S; Clegg, Simon L

2013-04-18

In previous studies (Dutcher et al. J. Phys. Chem. C 2011, 115, 16474-16487; 2012, 116, 1850-1864), we derived equations for the Gibbs energy, solvent and solute activities, and solute concentrations in multicomponent liquid mixtures, based upon expressions for adsorption isotherms that include arbitrary numbers of hydration layers on each solute. In this work, the long-range electrostatic interactions that dominate in dilute solutions are added to the Gibbs energy expression, thus extending the range of concentrations for which the model can be used from pure liquid solute(s) to infinite dilution in the solvent, water. An equation for the conversion of the reference state for solute activity coefficients to infinite dilution in water has been derived. A number of simplifications are identified, notably the equivalence of the sorption site parameters r and the stoichiometric coefficients of the solutes, resulting in a reduction in the number of model parameters. Solute concentrations in mixtures conform to a modified Zdanovskii-Stokes-Robinson mixing rule, and solute activity coefficients to a modified McKay-Perring relation, when the effects of the long-range (Debye-Hückel) term in the equations are taken into account. Practical applications of the equations to osmotic and activity coefficients of pure aqueous electrolyte solutions and mixtures show both satisfactory accuracy from low to high concentrations, together with a thermodynamically reasonable extrapolation (beyond the range of measurements) to extreme concentration and to the pure liquid solute(s).
Glass Transition Temperature of Saccharide Aqueous Solutions Estimated with the Free Volume/Percolation Model.

PubMed

Constantin, Julian Gelman; Schneider, Matthias; Corti, Horacio R

2016-06-09

The glass transition temperature of trehalose, sucrose, glucose, and fructose aqueous solutions has been predicted as a function of the water content by using the free volume/percolation model (FVPM). This model only requires the molar volume of water in the liquid and supercooled regimes, the molar volumes of the hypothetical pure liquid sugars at temperatures below their pure glass transition temperatures, and the molar volumes of the mixtures at the glass transition temperature. The model is simplified by assuming that the excess thermal expansion coefficient is negligible for saccharide-water mixtures, and this ideal FVPM becomes identical to the Gordon-Taylor model. It was found that the behavior of the water molar volume in trehalose-water mixtures at low temperatures can be obtained by assuming that the FVPM holds for this mixture. The temperature dependence of the water molar volume in the supercooled region of interest seems to be compatible with the recent hypothesis on the existence of two structure of liquid water, being the high density liquid water the state of water in the sugar solutions. The idealized FVPM describes the measured glass transition temperature of sucrose, glucose, and fructose aqueous solutions, with much better accuracy than both the Gordon-Taylor model based on an empirical kGT constant dependent on the saccharide glass transition temperature and the Couchman-Karasz model using experimental heat capacity changes of the components at the glass transition temperature. Thus, FVPM seems to be an excellent tool to predict the glass transition temperature of other aqueous saccharides and polyols solutions by resorting to volumetric information easily available.
Studies on the retention mechanism of solutes in hydrophilic interaction chromatography using stoichiometric displacement theory I. The linear relationship of lgk' vs. lg[H2O].

PubMed

Wang, Fei; Yang, Fan; Tian, Yang; Liu, Jiawei; Shen, Jiwei; Bai, Quan

2018-01-01

A stoichiometric displacement model for retention (SDM-R) of small solutes and proteins based on hydrophilic interaction chromatography (HILIC) was presented. A linear equation that related the logarithm of the capacity factor of the solute to the logarithm of the concentration of water in the mobile phase was derived. The stoichiometric displacement parameters, Z (the number of water molecules required to displace a solute from ligands) and lgI (containing a number of constants that relate to the affinity of solute to the ligands) could be obtained from the slope and the intercept of the linear plots of lgk' vs. lg[H 2 O]. The retention behaviors and retention mechanism of 15 kinds of small solutes and 6 kinds of proteins on 5 kinds HILIC columns with different ligands were investigated with SDM-R in typical range of water concentration in mobile phase. A good linear relationship between lgk' and lg[H 2 O] demonstrated that the most rational retention mechanism of solute in HILIC was a stoichiometric displacement process between solute and solvent molecules with water as displacing agents, which was not only valid for small solutes, but also could be used to explain the retention mechanism of biopolymers in HILIC. Comparing with the partition and adsorption models in HILIC, SDM-R was superior to them. Copyright © 2017 Elsevier B.V. All rights reserved.
Managing the potential risks of using bacteria-laden water in mineral processing to protect freshwater.

PubMed

Liu, Wenying; Moran, Chris J; Vink, Sue

2013-06-18

The minerals industry is being driven to access multiple water sources and increase water reuse to minimize freshwater withdrawal. Bacteria-laden water, such as treated effluent, has been increasingly used as an alternative to freshwater for mineral processing, in particular flotation, where conditions are favorable for bacterial growth. However, the risk posed by bacteria to flotation efficiency is poorly understood. This could be a barrier to the ongoing use of this water source. This study tested the potential of a previously published risk-based approach as a management tool to both assist mine sites in quantifying the risk from bacteria, and finding system-wide cost-effective solutions for risk mitigation. The result shows that the solution of adjusting the flotation chemical regime could only partly control the risk. The second solution of using tailings as an absorbent was shown to be effective in the laboratory in reducing bacterial concentration and thus removing the threat to flotation recovery. The best solution is likely to combine internal and external approaches, that is, inside and outside processing plants. Findings in this study contribute possible methods applicable to managing the risk from water-borne bacteria to plant operations that choose to use bacteria-containing water, when attempting to minimize freshwater use, and avoiding the undesirable consequences of increasing its use.
Atomic scale behavior of oxygen-based radicals in water

NASA Astrophysics Data System (ADS)

Verlackt, C. C. W.; Neyts, E. C.; Bogaerts, A.

2017-03-01

Cold atmospheric pressure plasmas in and in contact with liquids represent a growing field of research for various applications. Understanding the interactions between the plasma generated species and the liquid is crucial. In this work we perform molecular dynamics (MD) simulations based on a quantum mechanical method, i.e. density-functional based tight-binding (DFTB), to examine the interactions of OH radicals and O atoms in bulk water. Our calculations reveal that the transport of OH radicals through water is not only governed by diffusion, but also by an equilibrium reaction of H-abstraction with water molecules. Furthermore, when two OH radicals encounter each other, they either form a stable cluster, or react, resulting in the formation of a new water molecule and an O atom. In addition, the O atoms form either oxywater (when in singlet configuration) or they remain stable in solution (when in triplet configuration), stressing the important role that O atoms can play in aqueous solution, and in contact with biomolecules. Our observations are in line with both experimental and ab initio results from the literature.
Comparison of different advanced degradation processes for the removal of the pharmaceutical compounds diclofenac and carbamazepine from liquid solutions.

PubMed

Capodaglio, Andrea G; Bojanowska-Czajka, Anna; Trojanowicz, Marek

2018-04-18

Carbamazepine and diclofenac are two examples of drugs with widespread geographical and environmental media proliferation that are poorly removed by traditional wastewater treatment processes. Advanced oxidation processes (AOPs) have been proposed as alternative methods to remove these compounds in solution. AOPs are based on a wide class of powerful technologies, including UV radiation, ozone, hydrogen peroxide, Fenton process, catalytic wet peroxide oxidation, heterogeneous photocatalysis, electrochemical oxidation and their combinations, sonolysis, and microwaves applicable to both water and wastewater. Moreover, processes rely on the production of oxidizing radicals (•OH and others) in a solution to decompose present pollutants. Water radiolysis-based processes, which are an alternative to the former, involve the use of concentrated energy (beams of accelerated electrons or γ-rays) to split water molecules, generating strong oxidants and reductants (radicals) at the same time. In this paper, the degradation of carbamazepine and diclofenac by means of all these processes is discussed and compared. Energy and byproduct generation issues are also addressed.
Enthalpies of Dissolution of Crystalline Naproxen Sodium in Water and Potassium Hydroxide Aqueous Solutions at 298 K

NASA Astrophysics Data System (ADS)

Lytkin, A. I.; Chernikov, V. V.; Krutova, O. N.; Bychkova, S. A.; Volkov, A. V.; Skvortsov, I. A.

2018-03-01

The enthalpies of dissolution of crystalline naproxen sodium in water and aqueous solutions of KOH at 298.15 K are measured by direct calorimetric means in a wide range of concentrations. The acid-base properties of naproxen sodium at ionic strength I 0 and I = 0.1 (KNO3) and a temperature of 298.15 K are studied by spectrophotometric means. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of the formation of naproxen sodium and the products of its dissociation in aqueous solution are calculated.
The ISS Water Processor Catalytic Reactor as a Post Processor for Advanced Water Reclamation Systems

NASA Technical Reports Server (NTRS)

Nalette, Tim; Snowdon, Doug; Pickering, Karen D.; Callahan, Michael

2007-01-01

Advanced water processors being developed for NASA s Exploration Initiative rely on phase change technologies and/or biological processes as the primary means of water reclamation. As a result of the phase change, volatile compounds will also be transported into the distillate product stream. The catalytic reactor assembly used in the International Space Station (ISS) water processor assembly, referred to as Volatile Removal Assembly (VRA), has demonstrated high efficiency oxidation of many of these volatile contaminants, such as low molecular weight alcohols and acetic acid, and is considered a viable post treatment system for all advanced water processors. To support this investigation, two ersatz solutions were defined to be used for further evaluation of the VRA. The first solution was developed as part of an internal research and development project at Hamilton Sundstrand (HS) and is based primarily on ISS experience related to the development of the VRA. The second ersatz solution was defined by NASA in support of a study contract to Hamilton Sundstrand to evaluate the VRA as a potential post processor for the Cascade Distillation system being developed by Honeywell. This second ersatz solution contains several low molecular weight alcohols, organic acids, and several inorganic species. A range of residence times, oxygen concentrations and operating temperatures have been studied with both ersatz solutions to provide addition performance capability of the VRA catalyst.
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

Molecular Dynamics in Physiological Solutions: Force Fields, Alkali Metal Ions, and Ionic Strength.

PubMed

Zhang, Chao; Raugei, Simone; Eisenberg, Bob; Carloni, Paolo

2010-07-13

The monovalent ions Na(+) and K(+) and Cl(-) are present in any living organism. The fundamental thermodynamic properties of solutions containing such ions is given as the excess (electro-)chemical potential differences of single ions at finite ionic strength. This quantity is key for many biological processes, including ion permeation in membrane ion channels and DNA-protein interaction. It is given by a chemical contribution, related to the ion activity, and an electric contribution, related to the Galvani potential of the water/air interface. Here we investigate molecular dynamics based predictions of these quantities by using a variety of ion/water force fields commonly used in biological simulation, namely the AMBER (the newly developed), CHARMM, OPLS, Dang95 with TIP3P, and SPC/E water. Comparison with experiment is made with the corresponding values for salts, for which data are available. The calculations based on the newly developed AMBER force field with TIP3P water agrees well with experiment for both KCl and NaCl electrolytes in water solutions, as previously reported. The simulations based on the CHARMM-TIP3P and Dang95-SPC/E force fields agree well for the KCl and NaCl solutions, respectively. The other models are not as accurate. Single cations excess (electro-)chemical potential differences turn out to be similar for all the force fields considered here. In the case of KCl, the calculated electric contribution is consistent with higher level calculations. Instead, such agreement is not found with NaCl. Finally, we found that the calculated activities for single Cl(-) ions turn out to depend clearly on the type of counterion used, with all the force fields investigated. The implications of these findings for biomolecular systems are discussed.
Physics of lithium bromide (LiBr) solution dewatering through vapor venting membranes

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

Isfahani, RN; Fazeli, A; Bigham, S

2014-01-01

The physics of water desorption from a lithium bromide (LiBr) solution flow through an array of microchannels capped by a porous membrane is studied. The membrane allows the vapor to exit the flow and retains the liquid. Effects of different parameters such as wall temperature, solution and vapor pressures, and solution mass flux on the desorption rate were studied. Two different mechanisms of desorption are analyzed. These mechanisms consisted of: (1) direct diffusion of water molecules out of the solution and their subsequent flow through the membrane and (2) formation of water vapor bubbles within the solution and their ventingmore » through the membrane. Direct diffusion was the dominant desorption mode at low surface temperatures and its magnitude was directly related to the vapor pressure, the solution concentration, and the heated wall temperature. Desorption at the boiling regime was predominantly controlled by the solution flow pressure and mass flux. Microscale visualization studies suggested that at a critical mass flux, some bubbles are carried out of the desorber through the solution microchannels rather than being vented through the membrane. Overall, an order of magnitude higher desorption rate compare to a previous study on a membrane-based desorber was achieved. Published by Elsevier Ltd.« less
Removal of emerging micropollutants from water using cyclodextrin.

PubMed

Nagy, Zsuzsanna Magdolna; Molnár, Mónika; Fekete-Kertész, Ildikó; Molnár-Perl, Ibolya; Fenyvesi, Éva; Gruiz, Katalin

2014-07-01

Small scale laboratory experiment series were performed to study the suitability of a cyclodextrin-based sorbent (ß-cyclodextrin bead polymer, BCDP) for modelling the removal of micropollutants from drinking water and purified waste water using simulated inflow test solutions containing target analytes (ibuprofen, naproxen, ketoprofen, bisphenol-A, diclofenac, β-estradiol, ethinylestradiol, estriol, cholesterol at 2-6 μg/L level). This work was focused on the preliminary evaluation of BCDP as a sorbent in two different model systems (filtration and fluidization) applied for risk reduction of emerging micropollutants. For comparison different filter systems combined with various sorbents (commercial filter and activated carbon) were applied and evaluated in the filtration experiment series. The spiked test solution (inflow) and the treated outflows were characterized by an integrated methodology including chemical analytical methods gas chromatography-tandem mass spectrometry (GC-MS/MS) and various environmental toxicity tests to determine the efficiency and selectivity of the applied sorbents. Under experimental conditions the cyclodextrin-based filters used for purification of drinking water in most cases were able to absorb more than 90% of the bisphenol-A and of the estrogenic compounds. Both the analytical chemistry and toxicity results showed efficient elimination of these pollutants. Especially the toxicity of the filtrate decreased considerably. Laboratory experiment modelling post-purification of waste water was also performed applying fluidization technology by ß-cyclodextrin bead polymer. The BCDP removed efficiently from the spiked test solution most of the micropollutants, especially the bisphenol-A (94%) and the hormones (87-99%) The results confirmed that the BCDP-containing sorbents provide a good solution to water quality problems and they are able to decrease the load and risk posed by micropollutants to the water systems. Copyright © 2014 Elsevier B.V. All rights reserved.
Various nanoparticle morphologies and surface properties of waterborne polyurethane controlled by water

PubMed Central

Zhou, Xing; Fang, Changqing; Lei, Wanqing; Du, Jie; Huang, Tingyi; Li, Yan; Cheng, Youliang

2016-01-01

Water plays important roles in organic reactions such as polyurethane synthesis, and the aqueous solution environment affects polymer morphology and other properties. This paper focuses on the morphology and surface properties of waterborne polyurethane resulting from the organic reaction in water involving different forms (solid and liquid), temperatures and aqueous solutions. We provide evidence from TEM observations that the appearance of polyurethane nanoparticles in aqueous solutions presents diverse forms, including imperfect spheres, perfect spheres, perfect and homogenous spheres and tubes. Based on the results on FTIR, GPC, AFM and XRD experiments, we suggest that the shape of the nanoparticles may be decided by the crimp degree (i.e., the degree of polyurethane chains intertangling in the water environment) and order degree, which are determined by the molecular weight (Mn) and hydrogen bonds. Meanwhile, solid water and high-temperature water can both reduce hard segments that gather on the polyurethane film surface to reduce hydrophilic groups and produce a soft surface. Our findings show that water may play key roles in aqueous polymer formation and bring order to molecular chains. PMID:27687001
A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets

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

Knopf, Daniel A.; Alpert, Peter A.

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humiditymore » (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log 10(J het) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.« less
A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets.

PubMed

Knopf, Daniel A; Alpert, Peter A

2013-01-01

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, a(w), which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, J(het), to be uniquely expressed by T and a(w), a result we term the a(w) based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, J(het), frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(J(het)) values for the various IN types derived exclusively by Tand a(w), provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Lastly, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.
A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets

DOE PAGES

Knopf, Daniel A.; Alpert, Peter A.

2013-04-24

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humiditymore » (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log 10(J het) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.« less
Biologically Pre-Treated Habitation Waste Water as a Sustainable Green Urine Pre-Treat Solution

NASA Technical Reports Server (NTRS)

Jackson, W. Andrew; Thompson, Bret; Sevanthi, Ritesh; Morse, Audra; Meyer, Caitlin; Callahan, Michael

2017-01-01

The ability to recover water from urine and flush water is a critical process to allow long term sustainable human habitation in space or bases on the moon or mars. Organic N present as urea or similar compounds can hydrolyze producing free ammonia. This reaction results in an increase in the pH converting ammonium to ammonia which is volatile and not removed by distillation. The increase in pH will also cause precipitation reactions to occur. In order to prevent this, urine on ISS is combined with a pretreat solution. While use of a pretreatment solution has been successful, there are numerous draw backs including: storage and use of highly hazardous solutions, limitations on water recovery (less than 85%), and production of brine with pore dewatering characteristics. We evaluated the use of biologically treated habitation wastewaters (ISS and early planetary base) to replace the current pretreat solution. We evaluated both amended and un-amended bioreactor effluent. For the amended effluent, we evaluated "green" pretreat chemicals including citric acid and citric acid amended with benzoic acid. We used a mock urine/air separator modeled after the urine collection assembly on ISS. The urine/air separator was challenged continually for >6 months. Depending on the test point, the separator was challenged daily with donated urine and flushed with amended or un-amended reactor effluent. We monitored the pH of the urine, flush solution and residual pH in the urine/air separator after each urine event. We also evaluated solids production and biological growth. Our results support the use of both un-amended and amended bioreactor effluent to maintain the operability of the urine /air separator. The ability to use bioreactor effluent could decrease consumable cost, reduce hazards associated with current pre-treat chemicals, allow other membrane based desalination processes to be utilized, and improve brine characteristics.
Effects of Salinity and Confining Pressure on Hydration-Induced Fracture Propagation and Permeability of Mancos Shale

NASA Astrophysics Data System (ADS)

Zhang, Shifeng; Sheng, James J.

2017-11-01

Low-salinity water imbibition was considered an enhanced recovery method in shale oil/gas reservoirs due to the resulting hydration-induced fractures, as observed at ambient conditions. To study the effect of confining pressure and salinity on hydration-induced fractures, time-elapsed computerized tomography (CT) was used to obtain cross-sectional images of shale cores. Based on the CT data of these cross-sectional images, cut faces parallel to the core axial in the middle of the core and 3D fracture images were also reconstructed. To study the effects of confining pressure and salinity on shale pore fluid flowing, shale permeability was measured with Nitrogen (N2), distilled water, 4% KCl solution, and 8% KCl solution. With confining pressures increased to 2 MPa or more, either in distilled water or in KCl solutions of different salinities, fractures were observed to close instead to propagate at the end of the tests. The intrinsic permeabilities of #1 and #2 Mancos shale cores were 60.0 and 7000 nD, respectively. When tested with distilled water, the permeability of #1 shale sample with 20.0 MPa confining pressure loaded, and #2 shale sample with 2.5 MPa confining pressure loaded, decreased to 0.45 and 15 nD, respectively. Using KCl can partly mitigate shale permeability degradation. Compared to 4% KCl, 8% KCl can decrease more permeability damage. From this point of view, high salinity KCl solution should be required for the water-based fracturing fluid.
The SALT NORM : a quantitative chemical-mineralogical characterization of natural waters

USGS Publications Warehouse

Bodine, Marc W.; Jones, Blair F.

1986-01-01

The new computer program SNORM calculates the salt norm from the chemical composition of a natural water. The salt norm is the quantitative ideal equilibrium assemblage that would crystallize if the water evaporated to dryness at 25 C and 1 bar pressure under atmospheric partial pressure of CO2. SNORM proportions solute concentrations to achieve charge balance. It quantitatively distributes the 18 acceptable solutes into normative salts that are assigned from 63 possible normative salts to allow only stable associations based on the Gibbs Phase Rule, available free energy values, and observed low-temperature mineral associations. Although most natural water compositions represent multiple solute origins, results from SNORM identify three major categories: meteoric or weathering waters that are characterized by normative alkali-bearing sulfate and carbonate salts: connate marine-like waters that are chloride-rich with a halite-bischofite-carnallite-kieserite-anhydrite association; and diagenetic waters that are frequently of marine origin but yield normative salts, such as Ca-bearing chlorides (antarcticite and tachyhydrite) and sylvite, which suggest solute alteration by secondary mineral reactions. The solute source or reaction process within each of the above categories is commonly indicated by the presence or absence of diagnostic normative salts and their relative abundance in the normative salt assemblage. For example, salt norms: (1) may identify lithologic source; (2) may identify the relative roles of carbonic and sulfuric acid hydrolysis in the evolution of weathering waters; (3) may identify the origin of connate water from normal marine, hypersaline, or evaporite salt resolution processes; and (4) may distinguish between dolomitization and silicate hydrolysis or exchange for the origin of diagenetic waters. (Author 's abstract)
A Visual Aid for Teaching Basic Concepts of Soil-Water Physics.

ERIC Educational Resources Information Center

Eshel, Amram

1997-01-01

Presents a visual aid designed to generate an image of water movement among soil particles using an overhead projector to teach the physical phenomena related to water status and water movement in the soil. Utilizes a base plate of thin transparent plastic, opaque plastic sheets, a plate of glass, and a colored aqueous solution. (AIM)
Molybdenum-oxide based unique polyprotic nanoacids showing different deprotonations and related assembly processes in solution.

PubMed

Kistler, Melissa L; Liu, Tianbo; Gouzerh, Pierre; Todea, Ana Maria; Müller, Achim

2009-07-14

We report the self-assembly processes in solution of three Keplerate-type molybdenum-oxide based clusters {Mo72V30}, {Mo72Cr30} and {Mo72Fe30} (all with diameters of approximately 2.5 nm). These clusters behave as unique weak polyprotic acids owing to the external water ligands attached to the non-Mo metal centers. Whereas the Cr and Fe clusters have 30 water ligands attached at the 30 M3+ centers pointing outside, {Mo72V30} has 20 water ligands coordinated to vanadium atoms, of which only 10 are pointing outside. The self-assembly processes of the Keplerates leading to supramolecular blackberry-type structures are influenced by the effective charge densities on the cluster surfaces, which can be tuned by the pH values and solvent properties. As expected, {Mo72Cr30} and {Mo72Fe30} behave similarly in aqueous solution due to their analogous structures and in both cases the self-assembly follows the partial deprotonation of the external water ligands attached to the non-Mo metal centers. However, the M-OH2 functionalities differ not only in acidity but also lability, i.e. in different residence times of the H2O ligands. In contrast to {Mo72Cr30} and {Mo72Fe30}, the {Mo72V30} clusters carry a rather large number of negative charges so that their solution properties are different. They exist as discrete macroions in dilute aqueous solution, and form only in mixed water/organic solvent (like acetone) blackberry-type structures whose size increases with acetone content. The comparison of the properties of the clusters allows more general information about the interesting self-assembly phenomenon to be unveiled.
Review of the technological approaches for grey water treatment and reuses.

PubMed

Li, Fangyue; Wichmann, Knut; Otterpohl, Ralf

2009-05-15

Based on literature review, a non-potable urban grey water reuse standard is proposed and the treatment alternatives and reuse scheme for grey water reuses are evaluated according to grey water characteristics and the proposed standard. The literature review shows that all types of grey water have good biodegradability. The bathroom and the laundry grey water are deficient in both nitrogen and phosphors. The kitchen grey water has a balanced COD: N: P ratio. The review also reveals that physical processes alone are not sufficient to guarantee an adequate reduction of the organics, nutrients and surfactants. The chemical processes can efficiently remove the suspended solids, organic materials and surfactants in the low strength grey water. The combination of aerobic biological process with physical filtration and disinfection is considered to be the most economical and feasible solution for grey water recycling. The MBR appears to be a very attractive solution in collective urban residential buildings.
Non-Toxic, Low-Freezing, Drop-In Replacement Heat Transfer Fluids

NASA Technical Reports Server (NTRS)

Cutbirth, J. Michael

2012-01-01

A non-toxic, non-flammable, low-freezing heat transfer fluid is being developed for drop-in replacement within current and future heat transfer loops currently using water or alcohol-based coolants. Numerous water-soluble compounds were down-selected and screened for toxicological, physical, chemical, compatibility, thermodynamic, and heat transfer properties. Two fluids were developed, one with a freezing point near 0 C, and one with a suppressed freezing point. Both fluids contain an additive package to improve material compatibility and microbial resistance. The optimized sub-zero solution had a freezing point of 30 C, and a freezing volume expansion of 10-percent of water. The toxicity of the solutions was experimentally determined as LD(50) greater than 5g/kg. The solutions were found to produce minimal corrosion with materials identified by NASA as potentially existing in secondary cooling loops. Thermal/hydrodynamic performance exceeded that of glycol-based fluids with comparable freezing points for temperatures Tf greater than 20 C. The additive package was demonstrated as a buffering agent to compensate for CO2 absorption, and to prevent microbial growth. The optimized solutions were determined to have physically/chemically stable shelf lives for freeze/thaw cycles and longterm test loop tests.
ECLSS Sustaining Compatibility Testing on Urine Processor Assembly Nonmetallic Materials for Reformulation of Pretreated Urine Solution

NASA Technical Reports Server (NTRS)

Wingard, C. D.

2015-01-01

On International Space Station (ISS), the Urine Processor Assembly (UPA) converts human urine and flush water into potable water. The urine is acid-pretreated primarily to control microbial growth. In recent years, the sulfuric acid (H2SO4) pretreatment was believed to be largely responsible for producing salt crystals capable of plugging filters in UPA components and significantly reducing the percentage of water recovery from urine. In 2012, ISS management decided to change the acid pretreatment for urine from sulfuric to phosphoric with the goal of eliminating or minimizing formation of salt crystals. In 2013-2014, as part of the qualification of the phosphoric acid (H3PO4) formulation, samples of 12 nonmetallic materials used in UPA components were immersed for up to one year in pretreated urine and brine solutions made with the new H3PO4 formulation. Dynamic mechanical analysis (DMA) was used to measure modulus (stiffness) of the immersed samples compared to virgin control samples. Such compatibility data obtained by DMA for the H3PO4-based solutions were compared to DMA data obtained for the H2SO4-based solutions in 2002-2003.
A straightforward method for measuring the range of apparent density of microplastics.

PubMed

Li, Lingyun; Li, Mengmeng; Deng, Hua; Cai, Li; Cai, Huiwen; Yan, Beizhan; Hu, Jun; Shi, Huahong

2018-10-15

Density of microplastics has been regarded as the primary property that affect the distribution and bioavailability of microplastics in the water column. For measuring the density of microplastis, we developed a simple and rapid method based on density gradient solutions. In this study, we tested four solvents to make the density gradient solutions, i.e., ethanol (0.8 g/cm 3 ), ultrapure water (1.0 g/cm 3 ), saturated NaI (1.8 g/cm 3 ) and ZnCl 2 (1.8 g/cm 3 ). Density of microplastics was measured via observing the float or sink status in the density gradient solutions. We found that density gradient solutions made from ZnCl 2 had a larger uncertainty in measuring density than that from NaI, most likely due to a higher surface tension of ZnCl 2 solution. Solutions made from ethanol, ultrapure water, and NaI showed consistent density results with listed densities of commercial products, indicating that these density gradient solutions were suitable for measuring microplastics with a density range of 0.8-1.8 g/cm 3 . Copyright © 2018 Elsevier B.V. All rights reserved.
COMPILATION OF GROUND WATER MODELS

EPA Science Inventory

The full report presents an overview of currently available computer-based simulation models for ground-water flow, solute and heat transport, and hydrogeochemistry in both porous media and fractured rock. Separate sections address multiphase flow and related chemical species tra...
Quantifying Seepage Flux using Sediment Temperatures

EPA Science Inventory

This report provides a demonstration of different modeling approaches that use sediment temperatures to estimate the magnitude and direction of water flux across the groundwater-surface water transition zone. Analytical models based on steady-state or transient temperature solut...
Potential of Nanotechnology based water treatment solutions for the improvement of drinking water supplies in developing countries

NASA Astrophysics Data System (ADS)

Dutta, Joydeep; Bhattacharya, Prosun; Bundschuh, Jochen

2016-04-01

Over the last decades explosive population growth in the world has led to water scarcity across the globe putting additional pressure already scarce ground water resources and is pushing scientists and researchers to come up with new alternatives to monitor and treat water for use by mankind and for food security. Nearly 4 billion people around the world are known to lack access to clean water supply. Systematic water quality data is important for the assessment of health risks as well as for developing appropriate and affordable technologies for waste and drinking water treatments, and long-term decision making policy against water quality management. Traditional water treatment technologies are generally chemical-intensive processes requiring extremely large infrastructural support thus limiting their effective applications in developing nations which creates an artificial barrier to the application of technological solutions for the provision of clean water. Nanotechnology-based systems are in retrospect, smaller, energy and resource efficient. Economic impact assessment of the implementation of nanotechnology in water treatment and studies on cost-effectiveness and environmental and social impacts is of key importance prior to its wide spread acceptance. Government agencies and inter-governmental bodies driving research and development activities need to measure the effective potential of nanotechnology as a solution to global water challenges in order to effectively engage in fiscal, economic and social issues at national and international levels for different types of source waters with new national and international initiatives on nanotechnology and water need to be launched. Environmental pollution and industrialization in global scale is further leading to pollution of available water sources and thus hygienically friendly purification technologies are the need of the hour. Thus cost-effective treatment of pollutants for the transformation of hazardous substances into benign forms that can potentially be addressed through Nanotechnology based filters utilizing photocatalytic or electrocatalytic systems could be further explored. Development of these techniques together with other superadsorbants would make it possible to install delocalized systems with very little capital investment and operation and maintenance costs suitable for installation in less developed countries.
Improving sensitivity of gold nanoparticle based fluorescence quenching and colorimetric aptasensor by using water resuspended gold nanoparticle.

PubMed

Liu, Jinchuan; Guan, Zheng; Lv, Zhenzhen; Jiang, Xiaoling; Yang, Shuming; Chen, Ailiang

2014-02-15

Gold nanoparticles (AuNPs) based fluorescence quenching or colorimetric aptasensor have been developed for many analytes recently largely because of the ease of detection, high sensitivity, and potential for high-throughput analysis. However, the effects of remnant non-AuNPs components in the colloid gold solution on these assays performance remain unclear. For the first time, we demonstrated that the remnant sodium citrate and the reaction products of three acids play counteractive roles in AuNPs based fluorescence quenching and colorimetric aptasensor in three ways in this study. First, the remnant sodium citrate in the colloid gold solution could increase the fluorescence intensity of FAM labeled on the aptamer that reduce the efficiency of AuNPs fluorescent quenching. Second, the reaction products of citric acid, HCl and ketoglutaric acid reduce the fluorescence recovery by quenching the fluorescence of FAM labeled on the aptamer dissociated from the surface of AuNPs upon addition of target. Lastly, the reaction products of three acids reduce the pH value of the colloid gold solution that reduce the sensitivity of AuNPs based colorimetric aptasensor by increasing the adsorption of aptamer to surface of AuNPs. With sulfadimethoxine and thrombin as model analytes, we found that water resuspended AuNPs can significantly increase the sensitivity by more than 10-fold for AuNPs based fluorescence quenching aptasensor. In the AuNPs based colorimetric aptasensor for sulfadimethoxine using the water resuspended AuNPs, the sensitivity also was increased by 10-fold compared with that of original AuNPs. The findings in this study provide theoretical guidance for further improving AuNPs based fluorescent quenching and colorimetric aptasensor by adjusting the composition of AuNPs solution. © 2013 Elsevier B.V. All rights reserved.

Hydrologic exchange and chemical weathering in a proglacial watershed near Kangerlussuaq, west Greenland

NASA Astrophysics Data System (ADS)

Deuerling, Kelly M.; Martin, Jonathan B.; Martin, Ellen E.; Scribner, Cecilia A.

2018-01-01

The exchange of proglacial river water with active layer pore water could alter water chemical compositions in glacial outwash plains and oceanic solute fluxes. To evaluate effects of this exchange, we sampled Watson River and adjacent pore water during the 2013 melt season at two sandurs in western Greenland; one in Sandflugtdalen and the other near the confluence with Søndre Strømfjord. We measured temperature, specific conductivity, and head gradients between the river and bank over a week-long period at Sandflugtdalen, as well as sediment hydraulic conductivity and chemical compositions of waters from both sites. Specific conductivity of pore water is four to ten times greater than river water as solutes are concentrated from weathering reactions, cryoconcentration, and evaporation. Pore water compositions are predominantly altered by carbonate dissolution and sulfide mineral oxidation. High concentrations of HCO3 and SO4 result from solute recycling and dissolution of secondary Ca-Mg carbonate/sulfate salts initially formed by near-surface evaporation in the summer and at depth by freeze-in of the active layer and cryoconcentration in the winter. High hydraulic conductivity (10-5 to 10-4 m/s) and diurnal fluctuations of river stage during our study caused exchange of river and pore water immediately adjacent to the river channel, with a net loss of river water to the bank. Pore water >6 m from the river continuously flowed away from the river. Approximately 1-8% of the river discharge through the Sandflugtdalen was lost to the river bank during our 6.75 day study based on calculations using Darcy's Law. Although not sampled, some of this water should discharge to the river during low river stage early and late in the melt season. Elevated pore water solute concentrations in sandurs and water exchange at diurnal and seasonal frequency should impact fluxes of solutes to the ocean, although understanding the magnitude of this effect will require long-term evaluation throughout the melt season.
A Dynamic Eddy Viscosity Model for the Shallow Water Equations Solved by Spectral Element and Discontinuous Galerkin Methods

NASA Astrophysics Data System (ADS)

Marras, Simone; Suckale, Jenny; Giraldo, Francis X.; Constantinescu, Emil

2016-04-01

We present the solution of the viscous shallow water equations where viscosity is built as a residual-based subgrid scale model originally designed for large eddy simulation of compressible [1] and stratified flows [2]. The necessity of viscosity for a shallow water model not only finds motivation from mathematical analysis [3], but is supported by physical reasoning as can be seen by an analysis of the energetics of the solution. We simulated the flow of an idealized wave as it hits a set of obstacles. The kinetic energy spectrum of this flow shows that, although the inviscid Galerkin solutions -by spectral elements and discontinuous Galerkin [4]- preserve numerical stability in spite of the spurious oscillations in the proximity of the wave fronts, the slope of the energy cascade deviates from the theoretically expected values. We show that only a sufficiently small amount of dynamically adaptive viscosity removes the unwanted high-frequency modes while preserving the overall sharpness of the solution. In addition, it yields a physically plausible energy decay. This work is motivated by a larger interest in the application of a shallow water model to the solution of tsunami triggered coastal flows. In particular, coastal flows in regions around the world where coastal parks made of mitigation hills of different sizes and configurations are considered as a means to deviate the power of the incoming wave. References [1] M. Nazarov and J. Hoffman (2013) "Residual-based artificial viscosity for simulation of turbulent compressible flow using adaptive finite element methods" Int. J. Numer. Methods Fluids, 71:339-357 [2] S. Marras, M. Nazarov, F. X. Giraldo (2015) "Stabilized high-order Galerkin methods based on a parameter-free dynamic SGS model for LES" J. Comput. Phys. 301:77-101 [3] J. F. Gerbeau and B. Perthame (2001) "Derivation of the viscous Saint-Venant system for laminar shallow water; numerical validation" Discrete Contin. Dyn. Syst. Ser. B, 1:89?102 [4] F. X. Giraldo and M. Restelli (2010) "High-order semi-implicit time-integrators for a triangular discontinuous Galerkin oceanic shallow water model. Int. J. Numer. Methods Fluids, 63:1077-1102
A simple and rapid in situ preconcentration method for the determination of phosphate in environmental waters by use of solid-phase extraction, and its applications to brackish lake waters.

PubMed

Okumura, M; Tong, L; Fujinaga, K; Seike, Y

2001-05-01

A simple and rapid in situ preconcentration method for the determination of phosphate in environmental waters has been developed for field analysis. This method is based on solid-phase extraction on a zirconium-loaded Sep-Pack Accell CM cartridge (Zr-SP) and is applicable to studies in which sampling is performed by use of a graduated syringe to prevent contamination and to ensure easy operation at sampling sites. The Zr-SP cartridge was prepared by passing 0.1 mol L(-1) zirconium solution through a Sep-Pak Accell CM cartridge, packed with cation exchange sorbent based on a silica matrix. The adsorption of phosphate and its desorption depend only on the pH of the solution. A water sample containing phosphate was adjusted to pH 2 and passed through the Zr-SP cartridge to collect it. The retained phosphate was quantitatively eluted with 0.5 mol L(-1) sodium hydroxide solution. The phosphate retained in the Zr-SP cartridge was stable for at least one month. The established preconcentration method was successfully applied to brackish lake waters to investigate seasonal changes in the distribution and behavior of phosphate in a brackish lake.
Hydrogen-bonding and the sweet taste mechanism

NASA Astrophysics Data System (ADS)

Mathlouthi, M.; Portmann, M. O.

1990-09-01

The tripartite glucophores (AH-B,γ) of some natural (sugars) and artificial (Aspartame, Acesulfame, Saccharin, NHDHC and Trichlorogalactosucrose) sweeteners are proposed. These propositions are based on the molecular structure and infrared spectra of the studied molecules. The role of water in the sweet taste mechanism of small carbohydrates and artificial sweeteners was derived from the Raman spectra of their aqueous solutions. Comparison of the intensities and frequencies of the calculated components of the experimental Raman band of water on the one hand and of aqueous solutions of sweeteners on the other permitted interpretation of the role of water in the sweetness mechanism.
Solving multi-objective water management problems using evolutionary computation.

PubMed

Lewis, A; Randall, M

2017-12-15

Water as a resource is becoming increasingly more valuable given the changes in global climate. In an agricultural sense, the role of water is vital to ensuring food security. Therefore the management of it has become a subject of increasing attention and the development of effective tools to support participative decision-making in water management will be a valuable contribution. In this paper, evolutionary computation techniques and Pareto optimisation are incorporated in a model-based system for water management. An illustrative test case modelling optimal crop selection across dry, average and wet years based on data from the Murrumbidgee Irrigation Area in Australia is presented. It is shown that sets of trade-off solutions that provide large net revenues, or minimise environmental flow deficits can be produced rapidly, easily and automatically. The system is capable of providing detailed information on optimal solutions to achieve desired outcomes, responding to a variety of factors including climate conditions and economics. Copyright © 2017 Elsevier Ltd. All rights reserved.
Lanthanide-halide based humidity indicators

DOEpatents

Beitz, James V [Hinsdale, IL; Williams, Clayton W [Chicago, IL

2008-01-01

The present invention discloses a lanthanide-halide based humidity indicator and method of producing such indicator. The color of the present invention indicates the humidity of an atmosphere to which it is exposed. For example, impregnating an adsorbent support such as silica gel with an aqueous solution of the europium-containing reagent solution described herein, and dehydrating the support to dryness forms a substance with a yellow color. When this substance is exposed to a humid atmosphere the water vapor from the air is adsorbed into the coating on the pore surface of the silica gel. As the water content of the coating increases, the visual color of the coated silica gel changes from yellow to white. The color change is due to the water combining with the lanthanide-halide complex on the pores of the gel.
A Water-Soluble Fluorescent Probe for SO2 Derivatives in Aqueous Solution and Serum Based on Phenanthroimidazole Dye.

PubMed

Zhou, Yang; Wang, Ying; Xiao, Shuzhang; He, Xiafeng; Zhang, Nuonuo; Li, Dejiang; Zheng, Kaibo

2017-05-01

A water-soluble fluorescent SO 2 derivatives probe PI-SO 2 based on a phenanthroimidazole dye, and a sensitive SO 2 recognition site, aldehyde was constructed. The probe PI-SO 2 exhibits desirable properties such as high sensitivity, high selectivity and good water-solubility. Significantly, we have demonstrated that the probe PI-SO 2 is suitable for rapidly fluorescence detecting of SO 2 derivatives in aqueous solution and serum. The application of the novel probe PI-SO 2 proved that it was not only a useful tool for the detection of SO 2 derivatives in vitro, but also a potential assay for investigating the effects of SO 2 derivatives, and demonstrating its value in practical applicationin of complex biological samples.
Effect of pore water velocities and solute input methods on chloride transport in the undisturbed soil columns of Loess Plateau

NASA Astrophysics Data System (ADS)

Zhou, BeiBei; Wang, QuanJiu

2017-09-01

Studies on solute transport under different pore water velocity and solute input methods in undisturbed soil could play instructive roles for crop production. Based on the experiments in the laboratory, the effect of solute input methods with small pulse input and large pulse input, as well as four pore water velocities, on chloride transport in the undisturbed soil columns obtained from the Loess Plateau under controlled condition was studied. Chloride breakthrough curves (BTCs) were generated using the miscible displacement method under water-saturated, steady flow conditions. Using the 0.15 mol L-1 CaCl2 solution as a tracer, a small pulse (0.1 pore volumes) was first induced, and then, after all the solution was wash off, a large pulse (0.5 pore volumes) was conducted. The convection-dispersion equation (CDE) and the two-region model (T-R) were used to describe the BTCs, and their prediction accuracies and fitted parameters were compared as well. All the BTCs obtained for the different input methods and the four pore water velocities were all smooth. However, the shapes of the BTCs varied greatly; small pulse inputs resulted in more rapid attainment of peak values that appeared earlier with increases in pore water velocity, whereas large pulse inputs resulted in an opposite trend. Both models could fit the experimental data well, but the prediction accuracy of the T-R was better. The values of the dispersivity, λ, calculated from the dispersion coefficient obtained from the CDE were about one order of magnitude larger than those calculated from the dispersion coefficient given by the T-R, but the calculated Peclet number, Pe, was lower. The mobile-immobile partition coefficient, β, decreased, while the mass exchange coefficient increased with increases in pore water velocity.
Degradation of aqueous phenol solutions by coaxial DBD reactor

NASA Astrophysics Data System (ADS)

Dojcinovic, B. P.; Manojlovic, D.; Roglic, G. M.; Obradovic, B. M.; Kuraica, M. M.; Puric, J.

2008-07-01

Solutions of 2-chlorophenol, 4-chlorophenol and 2,6-dichlorophenol in bidistilled and water from the river Danube were treated in plasma reactor. In this reactor, based on coaxial dielectric barrier discharge at atmospheric pressure, plasma is formed over a thin layer of treated water. After one pass through the reactor, starting chlorophenols concentration of 20 mg/l was diminished up to 95 %. Kinetics of the chlorophenols degradation was monitored by High Pressure Liquid Chromatography method (HPLC).
Low-Temperature, Solution-Processed, Transparent Zinc Oxide-Based Thin-Film Transistors for Sensing Various Solvents.

PubMed

You, Hsin-Chiang; Wang, Cheng-Jyun

2017-02-26

A low temperature solution-processed thin-film transistor (TFT) using zinc oxide (ZnO) film as an exposed sensing semiconductor channel was fabricated to detect and identify various solution solvents. The TFT devices would offer applications for low-cost, rapid and highly compatible water-soluble detection and could replace conventional silicon field effect transistors (FETs) as bio-sensors. In this work, we demonstrate the utility of the TFT ZnO channel to sense various liquids, such as polar solvents (ethanol), non-polar solvents (toluene) and deionized (DI) water, which were dropped and adsorbed onto the channel. It is discussed how different dielectric constants of polar/non-polar solvents and DI water were associated with various charge transport properties, demonstrating the main detection mechanisms of the thin-film transistor.
Water based on a molecular model behaves like a hard-sphere solvent for a nonpolar solute when the reference interaction site model and related theories are employed

NASA Astrophysics Data System (ADS)

Hayashi, Tomohiko; Oshima, Hiraku; Harano, Yuichi; Kinoshita, Masahiro

2016-09-01

For neutral hard-sphere solutes, we compare the reduced density profile of water around a solute g(r), solvation free energy μ, energy U, and entropy S under the isochoric condition predicted by the two theories: dielectrically consistent reference interaction site model (DRISM) and angle-dependent integral equation (ADIE) theories. A molecular model for water pertinent to each theory is adopted. The hypernetted-chain (HNC) closure is employed in the ADIE theory, and the HNC and Kovalenko-Hirata (K-H) closures are tested in the DRISM theory. We also calculate g(r), U, S, and μ of the same solute in a hard-sphere solvent whose molecular diameter and number density are set at those of water, in which case the radial-symmetric integral equation (RSIE) theory is employed. The dependences of μ, U, and S on the excluded volume and solvent-accessible surface area are analyzed using the morphometric approach (MA). The results from the ADIE theory are in by far better agreement with those from computer simulations available for g(r), U, and μ. For the DRISM theory, g(r) in the vicinity of the solute is quite high and becomes progressively higher as the solute diameter d U increases. By contrast, for the ADIE theory, it is much lower and becomes further lower as d U increases. Due to unphysically positive U and significantly larger |S|, μ from the DRISM theory becomes too high. It is interesting that μ, U, and S from the K-H closure are worse than those from the HNC closure. Overall, the results from the DRISM theory with a molecular model for water are quite similar to those from the RSIE theory with the hard-sphere solvent. Based on the results of the MA analysis, we comparatively discuss the different theoretical methods for cases where they are applied to studies on the solvation of a protein.
Tautomeric equilibria of 5-fluorouracil anionic species in water.

PubMed

Markova, Nadezhda; Enchev, Venelin; Ivanova, Galya

2010-12-23

It has long been postulated that rare tautomeric or ionized forms of nucleic acid bases may play a role in mispair formation. Therefore, ab initio quantum chemical investigations on the tautomeric equilibrium in 5-fluorouracil (5FU) and its anions (deprotonated from N1, AN1, and from N3, AN3) and their tautomeric forms in water were performed. The effect of the water as solvent was introduced using solute-solvent clusters (four water molecules). The influence of the water molecules on the tautomeric reactions between different forms was considered by multiple proton transfer mechanisms. We show that when a water dimer is located in the reaction site between the two pairs of N-H and C═O groups, the assistive effect of the water molecules is strengthened. All calculations of the solute-water complexes were carried out at an MP2 level of theory and supplemented with correction for higher order correlation terms at CCSD(T) level, using the 6-31+G(d,p) basis set. The ab initio calculated frequencies and Raman intensities of 5FU and its anions AN1, AN3, and dianion are in good agreement with the experimental Raman frequencies in aqueous solution at different pH. In order to establish the pH-induced structural transformation in the molecule of 5FU, further (1)H, (19)F, and (13)C NMR spectra in water solution for pH = 6.9-13.8 were acquired and the chemical shift alterations were determined as a function of pH. On the basis of NMR spectroscopic data obtained for 5FU in aqueous solution at alkaline pH, we suggest the existence of a mixture of the anionic tautomeric forms predicted by our theoretical calculations.
Anisotropic membranes for gas separation

DOEpatents

Gollan, A.Z.

1987-07-21

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7--25 C and then air dried at ambient temperature, typically 10--30 C. 2 figs.
Bargaining over an international water resource based on cooperative game theory concepts

NASA Astrophysics Data System (ADS)

Madani, K.; Gholizadeh, S.

2011-12-01

Prior the collapse of the Soviet Union in 1991, Caspian Sea was peacefully shared by Iran and the USSR, based on the two historic treaties between Iran (Persia) and Russia. Collapse of the USSR gave birth to one of the world's serious conflicts over international water resources. Since then, the five littoral states of the Caspian Sea, namely Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan have been negotiating over finding an appropriate allocation scheme for sharing the sea and its valuable energy and environmental resources. Although several solution methods have been proposed, the negotiating parties have been unsuccessful in developing a compromise solution. A range of bargaining solutions are used here to show how cooperative game theory can be used to develop fair and efficient allocation schemes to resolve the Caspian Sea conflict. It is also examined how the negotiators may use their powers to change their shares from the Caspian Sea resources. Finally, the stability of the suggested game theoretic solutions are tested to find the solution which is more acceptable by the negotiating parties.
Seawater Upconing Under a Pumping Horizontal Well in a Confined Coastal Aquifer

NASA Astrophysics Data System (ADS)

Sun, D.; Zhan, H.

2003-12-01

Coastal margins are one of the nation_s greatest natural resources and economic assets. Due to increasing concentration of human settlements and economic activities in the coastal margins, it is critical to find better technologies of managing the coastal groundwater resources. Coastal aquifers always have saline water underneath the fresh water. This phenomenon substantially limits the groundwater pumping rates using traditional vertical wells because of the upconing of the fresh/saline water interfaces and the potential of sea water intrusion. With the advancement of horizontal well technology, we propose to use long-screen (kilometers) horizontal wells in coastal aquifers to increase groundwater supply and prevent sea water intrusion into those wells. In this study, we have developed two mathematical models to predict the equilibrium location of upconed sharp interfaces due to pumping horizontal wells based on the linear model of Muskat (1982) and the non-linear model of Dagan and Bear (1968) which described the upcoming due to a partially penetrating vertical pumping well. The horizontal well solution is obtained by integrating the point sink solution along the horizontal well axis. The linear solution based on Muskat_s model (1982) is acquired by neglecting the pressure field variation caused by the change of the fresh/saline water interface, while the nonlinear solution includes that variation. The computed interface profiles based on these two models are compared with those of vertical wells. The critical pumping rate is calculated and the sensitivity of the interface profile on aquifer anisotropy, horizontal well depth, and horizontal well length is tested. References: G. Dagan and J. Bear, Solving the problem of local interface upcoming in a coastal aquifer by the method of small perturbations, J. Hydraulic Research, 6, 15-44, 1968. Muskat, M, The flow of homogeneous Fluids Through Porous Media, International Human Resources Development Corporation, Boston, 763 PP, 1982.
A numerical method for osmotic water flow and solute diffusion with deformable membrane boundaries in two spatial dimension

NASA Astrophysics Data System (ADS)

Yao, Lingxing; Mori, Yoichiro

2017-12-01

Osmotic forces and solute diffusion are increasingly seen as playing a fundamental role in cell movement. Here, we present a numerical method that allows for studying the interplay between diffusive, osmotic and mechanical effects. An osmotically active solute obeys a advection-diffusion equation in a region demarcated by a deformable membrane. The interfacial membrane allows transmembrane water flow which is determined by osmotic and mechanical pressure differences across the membrane. The numerical method is based on an immersed boundary method for fluid-structure interaction and a Cartesian grid embedded boundary method for the solute. We demonstrate our numerical algorithm with the test case of an osmotic engine, a recently proposed mechanism for cell propulsion.
Predictive Sampling of Rare Conformational Events in Aqueous Solution: Designing a Generalized Orthogonal Space Tempering Method.

PubMed

Lu, Chao; Li, Xubin; Wu, Dongsheng; Zheng, Lianqing; Yang, Wei

2016-01-12

In aqueous solution, solute conformational transitions are governed by intimate interplays of the fluctuations of solute-solute, solute-water, and water-water interactions. To promote molecular fluctuations to enhance sampling of essential conformational changes, a common strategy is to construct an expanded Hamiltonian through a series of Hamiltonian perturbations and thereby broaden the distribution of certain interactions of focus. Due to a lack of active sampling of configuration response to Hamiltonian transitions, it is challenging for common expanded Hamiltonian methods to robustly explore solvent mediated rare conformational events. The orthogonal space sampling (OSS) scheme, as exemplified by the orthogonal space random walk and orthogonal space tempering methods, provides a general framework for synchronous acceleration of slow configuration responses. To more effectively sample conformational transitions in aqueous solution, in this work, we devised a generalized orthogonal space tempering (gOST) algorithm. Specifically, in the Hamiltonian perturbation part, a solvent-accessible-surface-area-dependent term is introduced to implicitly perturb near-solute water-water fluctuations; more importantly in the orthogonal space response part, the generalized force order parameter is generalized as a two-dimension order parameter set, in which essential solute-solvent and solute-solute components are separately treated. The gOST algorithm is evaluated through a molecular dynamics simulation study on the explicitly solvated deca-alanine (Ala10) peptide. On the basis of a fully automated sampling protocol, the gOST simulation enabled repetitive folding and unfolding of the solvated peptide within a single continuous trajectory and allowed for detailed constructions of Ala10 folding/unfolding free energy surfaces. The gOST result reveals that solvent cooperative fluctuations play a pivotal role in Ala10 folding/unfolding transitions. In addition, our assessment analysis suggests that because essential conformational events are mainly driven by the compensating fluctuations of essential solute-solvent and solute-solute interactions, commonly employed "predictive" sampling methods are unlikely to be effective on this seemingly "simple" system. The gOST development presented in this paper illustrates how to employ the OSS scheme for physics-based sampling method designs.
Water and solute transport parameterization form a soil of semi-arid region of northeast of Brazil

NASA Astrophysics Data System (ADS)

Netto, A. M.; Antonino, A. C. D.; Lima, L. J. S.; Angulo-Jaramillo, R.; Montenegro, S. M. G.

2003-04-01

Water and solute transfer modeling needs the transport parameters as input data. Classical theory, Fickian advection-dispersion, is not successfully applied to account for solute transport along with preferential flow pathways. This transport may be operating at scales smaller than spatial discretization used in a field scale numerical model. An axisymetric infiltration using a single ring infiltrometer along with a conservative tracer (Cl^-) is an efficient and easy method to use in fields tools. Two experiments were accomplished on a Yellow Oxissol in a 4,0 ha area in Centro de Ciências Agrárias, UFPB, Areia City, Paraíba State, Brazil (6^o 58'S, 35o 41'W and 645 m), in a 50 × 50 m grid (16 points): a) cultivated with beans (Vigna Unguinculata (L.) Walp.), and b) bare soil after harvest. The unsaturated hydraulic conductivity K and sorptivity S were estimated from short time or long time analysis of cumulative three dimensional infiltration. Single tracer technique was used for the calculation of mobile water fraction f by measuring the solute concentration underneath the ring infiltrometer, at the end of infiltration. A solute transfer numerical model, based on the mobile-immobile water concept, was used for the determination of the solute transport parameters. The mobile water fraction f, the dispersion coefficient D, and the mass transfer coefficient α, were estimated from both the measured infiltration depth and concentration profile underneath the ring infiltrometer. The presence of preferential flow was due to the soil nature (aggregated soil, macropores, flux instabilities and heterogeneity). The lateral solute transfer is not only diffusive but also convective. The parameters deduced from the numerical model associated to the solute profile concentration are representative of this phenomenon.
Water and Solute Flux Simulation Using Hydropedology Survey Data in South African Catchments

NASA Astrophysics Data System (ADS)

Lorentz, Simon; van Tol, Johan; le Roux, Pieter

2017-04-01

Hydropedology surveys include linking soil profile information in hillslope transects in order to define dominant subsurface flow mechanisms and pathways. This information is useful for deriving hillslope response functions, which aid storage and travel time estimates of water and solute movement in the sub-surface. In this way, the "soft" data of the hydropedological survey can be included in simple hydrological models, where detailed modelling of processes and pathways is prohibitive. Hydropedology surveys were conducted in two catchments and the information used to improve the prediction of water and solute responses. Typical hillslope response functions are then derived using a 2-D finite element model of the hydropedological features. Similar response types are mapped. These mapped response units are invoked in a simple SCS based, hydrological and solute transport model to yield water and solute fluxes at the catchment outlets. The first catchment (1.6 km2) comprises commercial forestry in a sedimentary geology of sandstone and mudstone formation while the second catchment (6.1 km2) includes mine waste impoundments in a granitic geology. In this paper, we demonstrate the method of combining hydropedological interpretation with catchment hydrology and solute transport simulation. The forested catchment, with three dominant hillslope response types, have solute response times in excess of 90 days, whereas the granitic responses occur within 10 days. The use of the hydropedological data improves the solute distribution response and storage simulation, compared to simulations without the hydropedology interpretation. The hydrological responses are similar, with and without the use of the hydropedology data, but the simulated distribution of water in the catchment is improved using the techniques demonstrated.
Effects of sodium hydroxide (NaOH) solution concentration on fly ash-based lightweight geopolymer

NASA Astrophysics Data System (ADS)

Ibrahim, W. M. W.; Hussin, K.; Abdullah, M. M. A.; Kadir, A. A.; Deraman, L. M.

2017-09-01

In this study, the effects of NaOH concentration on properties of fly ash-based lightweight geopolymer were investigated. Lightweight geopolymer was produced using fly ash as source materials and synthetic foaming agents as air entraining agent. The alkaline solutions used in this study are combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solution. Different molarities of NaOH solution (6M, 8M, 10M, 12M, and 14M) are taken for preparation of 50 x 50 x 50 mm cubes of lightweight geopolymer. The ratio of fly ash/alkaline solution, Na2SiO3/NaOH solution, foaming agent/water and foam/geopolymer paste were kept constant at 2.0, 2.5, 1:10 and 1:1 respectively. The samples were cured at 80°C for 24 hours and left at room temperature for tested at 7 days of ageing. Physical and mechanical properties such as density, water absorption, compressive strength and microstructure property were determined from the cube dried samples. The results show that the NaOH molarity had effects on the properties of lightweight geopolymer with the optimum NaOH molarity found is 12M due to the high strength of 15.6 MPa, lower water absorption (7.3%) and low density (1440 kg/m3). Microstructure analysis shows that the lightweight geopolymer contain some porous structure and unreacted fly ash particles remains.

Enhanced photoelectric performance in self-powered UV detectors based on ZnO nanowires with plasmonic Au nanoparticles scattered electrolyte

NASA Astrophysics Data System (ADS)

Zeng, Yiyu; Ye, Zhizhen; Lu, Bin; Dai, Wei; Pan, Xinhua

2016-04-01

Vertically aligned ZnO nanowires (NWs) were grown on a fluorine-doped tin-oxide-coated glass substrate by a hydrothermal method. Au nanoparticles were well dispersed in the mixed solution of ethanol and deionized water. A simple self-powered ultraviolet detector based on solid-liquid heterojunction was fabricated, utilizing ZnO NWs as active photoanode and such prepared mixed solution as electrolyte. The introduction of Au nanoparticles results in considerable improvements in the responsivity and sensitivity of the device compared with the one using deionized water as electrolyte, which is attributed to the enhanced light harvesting by Au nanoparticles.
Enhanced Performance of Thin Film Composite Forward Osmosis Membrane by Chemical Post-Treatment

NASA Astrophysics Data System (ADS)

Liu, Zheng; Chen, Jiangrong; Cao, Zhen; Wang, Jian; Guo, Chungang

2018-01-01

Forward osmosis is an attractive technique in water purification and desalination fields. Enhancement of the forward osmosis membrane performance is essential to the application of this technique. In this study, an optimized chemical post-treatment approach which was used to improve RO membrane performance was employed for enhancing water flux of thin film composite forward osmosis membrane. Home-made polysulfide-based forward osmosis membrane was prepared and nitric acid, sulfuric acid, ethanol, 2-propanol were employed as post-treatment solutions. After a short-term treatment, all the membrane samples manifested water flux enhancement compared with their untreated counterparts. Over 50% increase of water flux had been obtained by ethanol solution treatment. The swelling, changes of hydrophobicity and solvency in both active layer and substrate were verified as the major causes for the enhancement of the water flux. It is noted that the treatment time and solution concentration should be controlled to get both appropriate water flux and reverse salt flux. The results obtained in this study will be useful for further FO membrane development and application.
Solutions Network Formulation Report. Visible/Infrared Imager/Radiometer Suite and Landsat Data Continuity Mission Simulated Data Products for the Great Lakes Basin Ecological Team

NASA Technical Reports Server (NTRS)

Estep, Leland

2007-01-01

The proposed solution would simulate VIIRS and LDCM sensor data for use in the USGS/USFWS GLBET DST. The VIIRS sensor possesses a spectral range that provides water-penetrating bands that could be used to assess water clarity on a regional spatial scale. The LDCM sensor possesses suitable spectral bands in a range of wavelengths that could be used to map water quality at finer spatial scales relative to VIIRS. Water quality, alongshore sediment transport and pollutant discharge tracking into the Great Lakes system are targeted as the primary products to be developed. A principal benefit of water quality monitoring via satellite imagery is its economy compared to field-data collection methods. Additionally, higher resolution satellite imagery provides a baseline dataset(s) against which later imagery can be overlaid in GIS-based DST programs. Further, information derived from higher resolution satellite imagery can be used to address public concerns and to confirm environmental compliance. The candidate solution supports the Public Health, Coastal Management, and Water Management National Applications.
Effect of aluminum, zinc, copper, and lead on the acid-base properties of water extracts from soils

NASA Astrophysics Data System (ADS)

Motuzova, G. V.; Makarychev, I. P.; Petrov, M. I.

2013-01-01

The potentiometric titration of water extracts from the upper horizons of taiga-zone soils by salt solutions of heavy metals (Pb, Cu, and Zn) showed that their addition is an additional source of the extract acidity because of the involvement of the metal ions in complexation with water-soluble organic substances (WSOSs). At the addition of 0.01 M water solutions of Al(NO3)3 to water extracts from soils, Al3+ ions are also involved in complexes with WSOSs, which is accompanied by stronger acidification of the extracts from the upper horizon of soddy soils (with a near-neutral reaction) than from the litter of bog-podzolic soil (with a strongly acid reaction). The effect of the Al3+ hydrolysis on the acidity of the extracts is insignificantly low in both cases. A quantitative relationship was revealed between the release of protons and the ratio of free Cu2+ ions to those complexed with WSOSs at the titration of water extracts from soils by a solution of copper salt.
The analysis of the hot water consumption and energy performance before and after renovation in multi-apartment buildings

NASA Astrophysics Data System (ADS)

Tumanova, K.; Borodinecs, A.; Geikins, A.

2017-10-01

The article presents the results of hot water supply system analysis. Taking into account that the current consumption of hot water differs from normative values, real measured data of hot water consumption in multi-apartment buildings from year 2013 until year 2015 have been analyzed. Also, the thermal energy consumption for hot water preparation has been analyzed. Based on aggregated data and taking into account the fact that renovated systems of hot water supply in existing multi-apartment buildings have same pipelines’ diameters, it was analyzed how these systems are economically and energy efficient. For the study, residential buildings in Riga, which have different architectural and engineering solutions for hot water supply systems, were selected. The study was based on thermal energy consumption measurements, which were taken at the individual heating system’s manifolds. This study was done in order to develop database on hot water consumption in civil buildings and define difference in key performance criteria in unclassified buildings. Obtained results allows to reach European Regional Development Fund project “NEARLY ZERO ENERGY SOLUTIONS FOR UNCLASSIFIED BUILDINGS” Nr. 1.1.1.116A048 main targets.
A Facile All-Solution-Processed Surface with High Water Contact Angle and High Water Adhesive Force.

PubMed

Chen, Mei; Hu, Wei; Liang, Xiao; Zou, Cheng; Li, Fasheng; Zhang, Lanying; Chen, Feiwu; Yang, Huai

2017-07-12

A series of sticky superhydrophobicity surfaces with high water contact angle and high water adhesive force is facilely prepared via an all-solution-processed method based on polymerization-induced phase separation between liquid crystals (LCs) and epoxy resin, which produces layers of epoxy microspheres (EMSs) with nanofolds on the surface of a substrate. The morphologies and size distributions of EMSs are confirmed by scanning electron microscopy. Results reveal that the obtained EMS coated-surface exhibits high apparent contact angle of 152.0° and high water adhesive force up to 117.6 μN. By varying the composition of the sample or preparing conditions, the sizes of the produced EMSs can be artificially regulated and, thus, control the wetting properties and water adhesive behaviors. Also, the sticky superhydrophobic surface exhibits excellent chemical stability, as well as long-term durability. Water droplet transportation experiments further prove that the as-made surface can be effectively used as a mechanical hand for water transportation applications. Based on this, it is believed that the simple method proposed in this paper will pave a new way for producing a sticky superhydrophobic surface and obtain a wide range of use.
Dust control at longwalls with water infusion and foam. Technical progress report through November 30, 1982

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

Not Available

1982-01-01

Foam spray equipment and materials for dust suppression on longwall double drum shearer faces have been procured. This equipment includes metering pumps, foam generators and mounting brackets, foam solutions, flow meters, real time and gravimetric sampling equipment, hoses and valve banks. Initial tests have been conducted in the laboratory with three types of generators and five types of foam solutions. Based on these tests, Senior Conflow's cluster spray and Onyx Chemical Company's millifoam solution have been selected. For pumping foam solution to the shearer, Jon Bean's 2 hp, 120 VAC single-phase ceramic lined piston pump has been selected. For fieldmore » tests, equipment has been installed underground in Dobbin mine in Upper Freeport seam on Eickhoff EDW 300 double drum shearer. Foamspray tests have been conducted. Real time and gravimetric dust samples have been collected. Real time sampling results indicate a dust level reduction of up to 37 percent with foam spray compared to the base case of water sprays.« less
Bactericidal efficacy of glycine-type amphoteric surfactant as a denture cleaner and its influence on properties of denture base resins.

PubMed

Hashiguchi, Makiko; Nishi, Yasuhiro; Kanie, Takahito; Ban, Seiji; Nagaoka, Eiichi

2009-05-01

The bactericidal efficacy of 1.00-4.50% glycine-type amphoteric surfactant (Gly) was evaluated by measuring its microorganism removal rate in denture plaque. Physical and mechanical properties such as surface roughness, color difference, and bending strength of two different denture base resins were determined before and after cleaning in Gly solutions, a commercial denture cleaner, and tap water. The microorganism removal rates of all the Gly solutions were higher than those of a commercial enzymatic denture cleaner (Polident) (p>0.05). The removal rate of Candida spp. by Polident was not significantly different from the removal rate using water. Changes in the surface roughness and color difference among the specimens were slight. There were no significant differences in the bending strengths of the two resins for all concentrations of Gly solution (p>0.05). These results suggested that glycine-type amphoteric surfactant solution may be effective as a denture cleaner in conjunction with an ultrasonic cleaning device.
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.
Solar Metal Sulfate-Ammonia Based Thermochemical Water Splitting Cycle for Hydrogen Production

NASA Technical Reports Server (NTRS)

T-Raissi, Ali (Inventor); Muradov, Nazim (Inventor); Huang, Cunping (Inventor)

2014-01-01

Two classes of hybrid/thermochemical water splitting processes for the production of hydrogen and oxygen have been proposed based on (1) metal sulfate-ammonia cycles (2) metal pyrosulfate-ammonia cycles. Methods and systems for a metal sulfate MSO.sub.4--NH3 cycle for producing H2 and O2 from a closed system including feeding an aqueous (NH3)(4)SO3 solution into a photoctalytic reactor to oxidize the aqueous (NH3)(4)SO3 into aqueous (NH3)(2)SO4 and reduce water to hydrogen, mixing the resulting aqueous (NH3)(2)SO4 with metal oxide (e.g. ZnO) to form a slurry, heating the slurry of aqueous (NH4)(2)SO4 and ZnO(s) in the low temperature reactor to produce a gaseous mixture of NH3 and H2O and solid ZnSO4(s), heating solid ZnSO4 at a high temperature reactor to produce a gaseous mixture of SO2 and O2 and solid product ZnO, mixing the gaseous mixture of SO2 and O2 with an NH3 and H2O stream in an absorber to form aqueous (NH4)(2)SO3 solution and separate O2 for aqueous solution, recycling the resultant solution back to the photoreactor and sending ZnO to mix with aqueous (NH4)(2)SO4 solution to close the water splitting cycle wherein gaseous H2 and O2 are the only products output from the closed ZnSO4--NH3 cycle.
Laser-induced fluorescence spectrometer based on tunable color center laser for low-impurity-solution diagnostic and analysis

NASA Astrophysics Data System (ADS)

Basiev, Tasoltan T.; Fedorov, Vladimir V.; Karasik, Alexander Y.; Lin'kov, S. I.; Orlovskii, Yurii V.; Osiko, Vyacheslav V.; Panov, Vitaly A.; Prokhorov, Alexander M.; Vorob'ev, Ivan N.; Zverev, Peter G.

1996-11-01

Solid state (SS) tunable LiF:F2 color center laser with second and fourth harmonic generation for visible and ultra violet spectral ranges was developed for the laser induced fluorescence spectroscopy (LIFS). The construction and properties of excitation, registration and flame atomization systems for water solution diagnostic are discussed. The testing experiment with low iron concentrated water sample exhibits ultrahigh sensitivity which was estimated to be 0.05 ppb in our set-up. The SS LIFS spectrometer developed is usable to measure more than 42 metal elements in solution on the ppm, ppb level for various medical and biological applications.
The effect of low-GDP solution on ultrafiltration and solute transport in continuous ambulatory peritoneal dialysis patients.

PubMed

Cho, Kyu-Hyang; Do, Jun-Young; Park, Jong-Won; Yoon, Kyung-Woo; Kim, Yong-Lim

2013-01-01

Several studies have reported benefits for human peritoneal mesothelial cell function of a neutral-pH dialysate low in glucose degradation products (GDPs). However, the effects of low-GDP solution on ultrafiltration (UF), transport of solutes, and control of body water remain elusive. We therefore investigated the effect of low-GDP solution on UF, solute transport, and control of body water. Among 79 new continuous ambulatory peritoneal dialysis (CAPD) patients, 60 completed a 12-month protocol (28 in a lactate-based high-GDP solution group, 32 in a lactate-based low-GDP solution group). Clinical indices--including 24-hour UF volume (UFV), 24-hour urine volume (UV), residual renal function, and dialysis adequacy--were measured at months 1, 6, and 12. At months 1, 6, and 12, UFV, glucose absorption, 4-hour dialysate-to-plasma (D/P) creatinine, and 1-hour D/P Na(+) were assessed during a modified 4.25% peritoneal equilibration test (PET). Body composition by bioelectric impedance analysis was measured at months 1 and 12 in 26 CAPD patients. Daily UFV was lower in the low-GDP group. Despite similar solute transport and aquaporin function, the low-GDP group also showed lower UFV and higher glucose absorption during the PET. Factors associated with UFV during the PET were lactate-based high-GDP solution and 1-hour D/P Na(+). No differences in volume status and obesity at month 12 were observed, and improvements in hypervolemia were equal in both groups. Compared with the high-GDP group, the low-GDP group had a lower UFV during a PET and a lower daily UFV during the first year after peritoneal dialysis initiation. Although the low-GDP group had a lower daily UFV, no difficulties in controlling edema were encountered.
Nanofiber based triple layer hydro-philic/-phobic membrane - a solution for pore wetting in membrane distillation

PubMed Central

Prince, J. A.; Rana, D.; Matsuura, T.; Ayyanar, N.; Shanmugasundaram, T. S.; Singh, G.

2014-01-01

The innovative design and synthesis of nanofiber based hydro-philic/phobic membranes with a thin hydro-phobic nanofiber layer on the top and a thin hydrophilic nanofiber layer on the bottom of the conventional casted micro-porous layer which opens up a solution for membrane pore wetting and improves the pure water flux in membrane distillation. PMID:25377488
Stability of GO Modified by Different Dispersants in Cement Paste and Its Related Mechanism.

PubMed

Long, Wu-Jian; Fang, Changle; Wei, Jingjie; Li, Haodao

2018-05-18

Graphene oxide (GO) is a potential material to be used as a nano-reinforcement in cement matrix. However, a prerequisite for GO to fulfill its function in the cement matrix is homogeneous dispersion. In this study, the effects of three different dispersing agents (DAs), including polycarboxylate-based high range water reducer (P-HRWR), naphthalene-based high range water reducer (N-HRWR), and air entraining agent (AEA) on the dispersion of GO in aqueous solution, simulated concrete pore solution (SCPS), and suspension of cement pastes were sequentially investigated. Results showed that the dispersion effect of GO in aqueous solutions was improved with different DAs. However, the homogeneous dispersion of GO in aqueous solution re-agglomerated in SCPS and suspension of cement pastes. It was concluded that as the cement content and pH of aqueous solutions increased, GOs re-agglomerated and precipitated in an alkaline solution. A possible mechanism was proposed in this study and it was believed that electrostatic interactions and steric hindrance provided by the P-HRWR further made GOs stable in aqueous solutions. The ions and pH of cement pastes increased with the increasing amount of cement, which caused the separation of P-HRWR from GOs. Therefore, GOs were re-agglomerated and absorbed on the surface of the cement particles, resulting in GOs sedimentation.
Non-linear osmosis

PubMed Central

Diamond, Jared M.

1966-01-01

1. The relation between osmotic gradient and rate of osmotic water flow has been measured in rabbit gall-bladder by a gravimetric procedure and by a rapid method based on streaming potentials. Streaming potentials were directly proportional to gravimetrically measured water fluxes. 2. As in many other tissues, water flow was found to vary with gradient in a markedly non-linear fashion. There was no consistent relation between the water permeability and either the direction or the rate of water flow. 3. Water flow in response to a given gradient decreased at higher osmolarities. The resistance to water flow increased linearly with osmolarity over the range 186-825 m-osM. 4. The resistance to water flow was the same when the gall-bladder separated any two bathing solutions with the same average osmolarity, regardless of the magnitude of the gradient. In other words, the rate of water flow is given by the expression (Om — Os)/[Ro′ + ½k′ (Om + Os)], where Ro′ and k′ are constants and Om and Os are the bathing solution osmolarities. 5. Of the theories advanced to explain non-linear osmosis in other tissues, flow-induced membrane deformations, unstirred layers, asymmetrical series-membrane effects, and non-osmotic effects of solutes could not explain the results. However, experimental measurements of water permeability as a function of osmolarity permitted quantitative reconstruction of the observed water flow—osmotic gradient curves. Hence non-linear osmosis in rabbit gall-bladder is due to a decrease in water permeability with increasing osmolarity. 6. The results suggest that aqueous channels in the cell membrane behave as osmometers, shrinking in concentrated solutions of impermeant molecules and thereby increasing membrane resistance to water flow. A mathematical formulation of such a membrane structure is offered. PMID:5945254
Electrodialytic in-line preconcentration for ionic solute analysis.

PubMed

Ohira, Shin-Ichi; Yamasaki, Takayuki; Koda, Takumi; Kodama, Yuko; Toda, Kei

2018-04-01

Preconcentration is an effective way to improve analytical sensitivity. Many types of methods are used for enrichment of ionic solute analytes. However, current methods are batchwise and include procedures such as trapping and elution. In this manuscript, we propose in-line electrodialytic enrichment of ionic solutes. The method can enrich ionic solutes within seconds by quantitative transfer of analytes from the sample solution to the acceptor solution under an electric field. Because of quantitative ion transfer, the enrichment factor (the ratio of the concentration in the sample and to that in the obtained acceptor solution) only depends on the flow rate ratio of the sample solution to the acceptor solution. The ratios of the concentrations and flow rates are equal for ratios up to 70, 20, and 70 for the tested ionic solutes of inorganic cations, inorganic anions, and heavy metal ions, respectively. The sensitivity of ionic solute determinations is also improved based on the enrichment factor. The method can also simultaneously achieve matrix isolation and enrichment. The method was successively applied to determine the concentrations of trace amounts of chloroacetic acids in tap water. The regulated concentration levels cannot be determined by conventional high-performance liquid chromatography with ultraviolet detection (HPLC-UV) without enrichment. However, enrichment with the present method is effective for determination of tap water quality by improving the limits of detection of HPLC-UV. The standard addition test with real tap water samples shows good recoveries (94.9-109.6%). Copyright © 2017 Elsevier B.V. All rights reserved.
A simple and efficient anionic chromogenic chemosensor based on 2,4-dinitrodiphenylamine in dimethyl sulfoxide and in dimethyl sulfoxide-water mixtures

NASA Astrophysics Data System (ADS)

Marini, Vanderléia Gava; Zimmermann, Lizandra Maria; Machado, Vanderlei Gageiro

2010-02-01

Solutions of 2,4-dinitrodiphenylamine ( 1) in dimethylsulfoxide (DMSO) are colorless but upon deprotonation they become red. Addition of various anionic species (HSO 4-, H 2PO 4-, NO 3-, CN -, CH 3COO -, F -, Cl -, Br -, and I -) to solutions of 1 revealed that only CN -, F -, CH 3COO -, and H 2PO 4- led to the appearance of the red color in solution. The presence of increasing amounts of water in solutions containing 1 made it progressively selective toward CN - and the system with the addition of 4.3% (v/v) of water was highly selective for CN - among all anions studied. The experimental data collected indicated that proton transfer from 1 to the anion occurs, and a model was used to explain the experimental results, which considers two 1:anion stoichiometries, 1:1 and 1:2. For the latter, the data suggest that the anion forms firstly a hydrogen-bonded complex with a second anion equivalent necessary for the abstraction of the proton, with the formation of a [HA 2] - complex. The study performed here demonstrates the important role of the environment of the anion and 1 for the efficiency of the chromogenic chemosensor. Besides the different affinities of each anion for water, the solvation of both the anion and 1 is responsible for reducing the interaction between these species. In small amounts, water or hydrogen-bonded DMSO-water complexes are able to stabilize the conjugated base of 1 through hydrogen bonding, making 1 more acidic, which explains the change from 1:1 and 1:2 toward 1:1 1:anion stoichiometry upon addition of water. In addition, water is able to solvate the anion and also 1, which hinders the formation of 1:1 hydrogen-bonded 1:anion complexes prior to the abstraction of the proton.
Quantum chemistry in arbitrary dielectric environments: Theory and implementation of nonequilibrium Poisson boundary conditions and application to compute vertical ionization energies at the air/water interface

NASA Astrophysics Data System (ADS)

Coons, Marc P.; Herbert, John M.

2018-06-01

Widely used continuum solvation models for electronic structure calculations, including popular polarizable continuum models (PCMs), usually assume that the continuum environment is isotropic and characterized by a scalar dielectric constant, ɛ. This assumption is invalid at a liquid/vapor interface or any other anisotropic solvation environment. To address such scenarios, we introduce a more general formalism based on solution of Poisson's equation for a spatially varying dielectric function, ɛ(r). Inspired by nonequilibrium versions of PCMs, we develop a similar formalism within the context of Poisson's equation that includes the out-of-equilibrium dielectric response that accompanies a sudden change in the electron density of the solute, such as that which occurs in a vertical ionization process. A multigrid solver for Poisson's equation is developed to accommodate the large spatial grids necessary to discretize the three-dimensional electron density. We apply this methodology to compute vertical ionization energies (VIEs) of various solutes at the air/water interface and compare them to VIEs computed in bulk water, finding only very small differences between the two environments. VIEs computed using approximately two solvation shells of explicit water molecules are in excellent agreement with experiment for F-(aq), Cl-(aq), neat liquid water, and the hydrated electron, although errors for Li+(aq) and Na+(aq) are somewhat larger. Nonequilibrium corrections modify VIEs by up to 1.2 eV, relative to models based only on the static dielectric constant, and are therefore essential to obtain agreement with experiment. Given that the experiments (liquid microjet photoelectron spectroscopy) may be more sensitive to solutes situated at the air/water interface as compared to those in bulk water, our calculations provide some confidence that these experiments can indeed be interpreted as measurements of VIEs in bulk water.
A simple and efficient anionic chromogenic chemosensor based on 2,4-dinitrodiphenylamine in dimethyl sulfoxide and in dimethyl sulfoxide-water mixtures.

PubMed

Marini, Vanderléia Gava; Zimmermann, Lizandra Maria; Machado, Vanderlei Gageiro

2010-02-01

Solutions of 2,4-dinitrodiphenylamine (1) in dimethylsulfoxide (DMSO) are colorless but upon deprotonation they become red. Addition of various anionic species (HSO(4)(-), H(2)PO(4)(-), NO(3)(-), CN(-), CH(3)COO(-), F(-), Cl(-), Br(-), and I(-)) to solutions of 1 revealed that only CN(-), F(-), CH(3)COO(-), and H(2)PO(4)(-) led to the appearance of the red color in solution. The presence of increasing amounts of water in solutions containing 1 made it progressively selective toward CN(-) and the system with the addition of 4.3% (v/v) of water was highly selective for CN(-) among all anions studied. The experimental data collected indicated that proton transfer from 1 to the anion occurs, and a model was used to explain the experimental results, which considers two 1:anion stoichiometries, 1:1 and 1:2. For the latter, the data suggest that the anion forms firstly a hydrogen-bonded complex with a second anion equivalent necessary for the abstraction of the proton, with the formation of a [HA(2)](-) complex. The study performed here demonstrates the important role of the environment of the anion and 1 for the efficiency of the chromogenic chemosensor. Besides the different affinities of each anion for water, the solvation of both the anion and 1 is responsible for reducing the interaction between these species. In small amounts, water or hydrogen-bonded DMSO-water complexes are able to stabilize the conjugated base of 1 through hydrogen bonding, making 1 more acidic, which explains the change from 1:1 and 1:2 toward 1:1 1:anion stoichiometry upon addition of water. In addition, water is able to solvate the anion and also 1, which hinders the formation of 1:1 hydrogen-bonded 1:anion complexes prior to the abstraction of the proton. Copyright (c) 2009 Elsevier B.V. All rights reserved.
Quantum chemistry in arbitrary dielectric environments: Theory and implementation of nonequilibrium Poisson boundary conditions and application to compute vertical ionization energies at the air/water interface.

PubMed

Coons, Marc P; Herbert, John M

2018-06-14

Widely used continuum solvation models for electronic structure calculations, including popular polarizable continuum models (PCMs), usually assume that the continuum environment is isotropic and characterized by a scalar dielectric constant, ε. This assumption is invalid at a liquid/vapor interface or any other anisotropic solvation environment. To address such scenarios, we introduce a more general formalism based on solution of Poisson's equation for a spatially varying dielectric function, ε(r). Inspired by nonequilibrium versions of PCMs, we develop a similar formalism within the context of Poisson's equation that includes the out-of-equilibrium dielectric response that accompanies a sudden change in the electron density of the solute, such as that which occurs in a vertical ionization process. A multigrid solver for Poisson's equation is developed to accommodate the large spatial grids necessary to discretize the three-dimensional electron density. We apply this methodology to compute vertical ionization energies (VIEs) of various solutes at the air/water interface and compare them to VIEs computed in bulk water, finding only very small differences between the two environments. VIEs computed using approximately two solvation shells of explicit water molecules are in excellent agreement with experiment for F - (aq), Cl - (aq), neat liquid water, and the hydrated electron, although errors for Li + (aq) and Na + (aq) are somewhat larger. Nonequilibrium corrections modify VIEs by up to 1.2 eV, relative to models based only on the static dielectric constant, and are therefore essential to obtain agreement with experiment. Given that the experiments (liquid microjet photoelectron spectroscopy) may be more sensitive to solutes situated at the air/water interface as compared to those in bulk water, our calculations provide some confidence that these experiments can indeed be interpreted as measurements of VIEs in bulk water.

Metabolite extraction from adherently growing mammalian cells for metabolomics studies: optimization of harvesting and extraction protocols.

PubMed

Dettmer, Katja; Nürnberger, Nadine; Kaspar, Hannelore; Gruber, Michael A; Almstetter, Martin F; Oefner, Peter J

2011-01-01

Trypsin/ethylenediaminetetraacetic acid (EDTA) treatment and cell scraping in a buffer solution were compared for harvesting adherently growing mammalian SW480 cells for metabolomics studies. In addition, direct scraping with a solvent was tested. Trypsinated and scraped cell pellets were extracted using seven different extraction protocols including pure methanol, methanol/water, pure acetone, acetone/water, methanol/chloroform/water, methanol/isopropanol/water, and acid-base methanol. The extracts were analyzed by GC-MS after methoximation/silylation and derivatization with propyl chloroformate, respectively. The metabolic fingerprints were compared and 25 selected metabolites including amino acids and intermediates of energy metabolism were quantitatively determined. Moreover, the influence of freeze/thaw cycles, ultrasonication and homogenization using ceramic beads on extraction yield was tested. Pure acetone yielded the lowest extraction efficiency while methanol, methanol/water, methanol/isopropanol/water, and acid-base methanol recovered similar metabolite amounts with good reproducibility. Based on overall performance, methanol/water was chosen as a suitable extraction solvent. Repeated freeze/thaw cycles, ultrasonication and homogenization did not improve overall metabolite yield of the methanol/water extraction. Trypsin/EDTA treatment caused substantial metabolite leakage proving it inadequate for metabolomics studies. Gentle scraping of the cells in a buffer solution and subsequent extraction with methanol/water resulted on average in a sevenfold lower recovery of quantified metabolites compared with direct scraping using methanol/water, making the latter one the method of choice to harvest and extract metabolites from adherently growing mammalian SW480 cells.
A Comparison of Numerical and Analytical Radiative-Transfer Solutions for Plane Albedo of Natural Waters

EPA Science Inventory

Three numerical algorithms were compared to provide a solution of a radiative transfer equation (RTE) for plane albedo (hemispherical reflectance) in semi-infinite one-dimensional plane-parallel layer. Algorithms were based on the invariant imbedding method and two different var...
HYDRAULIC ANALYSIS OF BASE-FLOW AND BANK STORAGE IN ALLUVIAL STREAMS

EPA Science Inventory

This paper presents analytical solutions, which describe the effect of time-variable net recharge (net accretion to water table) and bank storage in alluvial aquifers on the sustenance of stream flows during storm and inter-storm events. The solutions relate the stream discharge,...
Boundary layer flow of air over water on a flat plate

NASA Technical Reports Server (NTRS)

Nelson, John; Alving, Amy E.; Joseph, Daniel D.

1993-01-01

A non-similar boundary layer theory for air blowing over a water layer on a flat plate is formulated and studied as a two-fluid problem in which the position of the interface is unknown. The problem is considered at large Reynolds number (based on x), away from the leading edge. A simple non-similar analytic solution of the problem is derived for which the interface height is proportional to x(sub 1/4) and the water and air flow satisfy the Blasius boundary layer equations, with a linear profile in the water and a Blasius profile in the air. Numerical studies of the initial value problem suggests that this asymptotic, non-similar air-water boundary layer solution is a global attractor for all initial conditions.
Antimicrobial effects of electrolytic products of sodium chloride--comparative evaluation with sodium hypochlorite solution and efficacy in handwashing.

PubMed

Hitomi, S; Baba, S; Yano, H; Morisawa, Y; Kimura, S

1998-11-01

We examined the in vitro bactericidal effects and efficacy on handwashing of water containing electrolytic products of sodium chloride (electrolytic water). The electrolytic water, whose pH and concentration of free residual chlorine were 6.7-6.9 and 20-22 ppm, respectively, showed equal reduction of both Staphylococcus aureus and Escherichia coli to dilution of commercially available sodium hypochlorite containing 60 ppm of free residual chlorine. This bactericidal effect was calculated to be due to hypochlorous acid, based on the pH and the amount of chlorine in solution. Handwashing with the electrolytic water reduced the numbers of S. aureus on hands by 1/10(2), while running water and 0.2% benzalkonium chloride with 80% ethanol gave a 1/10 and 1/10(5) reduction, respectively. We conclude that electrolytic water might be applicable for handwashing in place of running water.
Material properties that predict preservative uptake for silicone hydrogel contact lenses.

PubMed

Green, J Angelo; Phillips, K Scott; Hitchins, Victoria M; Lucas, Anne D; Shoff, Megan E; Hutter, Joseph C; Rorer, Eva M; Eydelman, Malvina B

2012-11-01

To assess material properties that affect preservative uptake by silicone hydrogel lenses. We evaluated the water content (using differential scanning calorimetry), effective pore size (using probe penetration), and preservative uptake (using high-performance liquid chromatography with spectrophotometric detection) of silicone and conventional hydrogel soft contact lenses. Lenses grouped similarly based on freezable water content as they did based on total water content. Evaluation of the effective pore size highlighted potential differences between the surface-treated and non-surface-treated materials. The water content of the lens materials and ionic charge are associated with the degree of preservative uptake. The current grouping system for testing contact lens-solution interactions separates all silicone hydrogels from conventional hydrogel contact lenses. However, not all silicone hydrogel lenses interact similarly with the same contact lens solution. Based upon the results of our research, we propose that the same material characteristics used to group conventional hydrogel lenses, water content and ionic charge, can also be used to predict uptake of hydrophilic preservatives for silicone hydrogel lenses. In addition, the hydrophobicity of silicone hydrogel contact lenses, although not investigated here, is a unique contact lens material property that should be evaluated for the uptake of relatively hydrophobic preservatives and tear components.
A potential model for sodium chloride solutions based on the TIP4P/2005 water model

NASA Astrophysics Data System (ADS)

Benavides, A. L.; Portillo, M. A.; Chamorro, V. C.; Espinosa, J. R.; Abascal, J. L. F.; Vega, C.

2017-09-01

Despite considerable efforts over more than two decades, our knowledge of the interactions in electrolyte solutions is not yet satisfactory. Not even one of the most simple and important aqueous solutions, NaCl(aq), escapes this assertion. A requisite for the development of a force field for any water solution is the availability of a good model for water. Despite the fact that TIP4P/2005 seems to fulfill the requirement, little work has been devoted to build a force field based on TIP4P/2005. In this work, we try to fill this gap for NaCl(aq). After unsuccessful attempts to produce accurate predictions for a wide range of properties using unity ionic charges, we decided to follow recent suggestions indicating that the charges should be scaled in the ionic solution. In this way, we have been able to develop a satisfactory non-polarizable force field for NaCl(aq). We evaluate a number of thermodynamic properties of the solution (equation of state, maximum in density, enthalpies of solution, activity coefficients, radial distribution functions, solubility, surface tension, diffusion coefficients, and viscosity). Overall the results for the solution are very good. An important achievement of our model is that it also accounts for the dynamical properties of the solution, a test for which the force fields so far proposed failed. The same is true for the solubility and for the maximum in density where the model describes the experimental results almost quantitatively. The price to pay is that the model is not so good at describing NaCl in the solid phase, although the results for several properties (density and melting temperature) are still acceptable. We conclude that the scaling of the charges improves the overall description of NaCl aqueous solutions when the polarization is not included.
Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures.

PubMed

Cochrane, T T; Cochrane, T A

2016-01-01

To demonstrate that the authors' new "aqueous solution vs pure water" equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of "free" water molecules per unit volume of solution, "Nf," and (c) the "t" factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate Nf was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors' equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. The provisional equations formulated to calculate Nf, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of Nf using recorded relative density data at 20 °C. They were subsequently used to estimate Nf values at temperatures up to and excess of body temperatures. Those values, together with t values at temperatures up to and in excess of body temperatures recorded in the literature, were substituted in the authors' equation for the provisional calculation of osmotic potentials. The calculations indicated that solution temperatures and solute concentrations have a marked effect on osmotic potentials. Following work to measure the relative densities of aqueous solutions for the calculation of Nf values and the determination of definitive t values up to and beyond bodily temperatures, the authors' equation would enable the accurate estimations of the osmotic potentials of wide concentrations of aqueous solutions of inorganic and organic solutes over the temperature range. The study illustrates that not only solute concentrations but also temperatures have a marked effect on osmotic potentials, an observation of medical and biological significance.
National water, food, and trade modeling framework: The case of Egypt.

PubMed

Abdelkader, A; Elshorbagy, A; Tuninetti, M; Laio, F; Ridolfi, L; Fahmy, H; Hoekstra, A Y

2018-10-15

This paper introduces a modeling framework for the analysis of real and virtual water flows at national scale. The framework has two components: (1) a national water model that simulates agricultural, industrial and municipal water uses, and available water and land resources; and (2) an international virtual water trade model that captures national virtual water exports and imports related to trade in crops and animal products. This National Water, Food & Trade (NWFT) modeling framework is applied to Egypt, a water-poor country and the world's largest importer of wheat. Egypt's food and water gaps and the country's food (virtual water) imports are estimated over a baseline period (1986-2013) and projected up to 2050 based on four scenarios. Egypt's food and water gaps are growing rapidly as a result of steep population growth and limited water resources. The NWFT modeling framework shows the nexus of the population dynamics, water uses for different sectors, and their compounding effects on Egypt's food gap and water self-sufficiency. The sensitivity analysis reveals that for solving Egypt's water and food problem non-water-based solutions like educational, health, and awareness programs aimed at lowering population growth will be an essential addition to the traditional water resources development solution. Both the national and the global models project similar trends of Egypt's food gap. The NWFT modeling framework can be easily adapted to other nations and regions. Copyright © 2018. Published by Elsevier B.V.
Effect of chlorides on solution corrosivity of methyldiethanolamine (MDEA) solutions

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

Rooney, P.C.; Bacon, T.R.; DuPart, M.S.

1997-08-01

Solution corrosivity of MDEA/water solutions containing added HCl or NaCl have been measured by weight loss coupons at 250 F and by linear polarization resistance (LPR) at 208 F using carbon steel, 304SS, 316SS and 410SS. General corrosion as well as pitting or crevice corrosion tendencies were recorded for each species. Based on these results, recommendations are made for chlorides in MDEA that minimizes corrosion in gas treating operations.
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.
Algorithms for optimization of branching gravity-driven water networks

NASA Astrophysics Data System (ADS)

Dardani, Ian; Jones, Gerard F.

2018-05-01

The design of a water network involves the selection of pipe diameters that satisfy pressure and flow requirements while considering cost. A variety of design approaches can be used to optimize for hydraulic performance or reduce costs. To help designers select an appropriate approach in the context of gravity-driven water networks (GDWNs), this work assesses three cost-minimization algorithms on six moderate-scale GDWN test cases. Two algorithms, a backtracking algorithm and a genetic algorithm, use a set of discrete pipe diameters, while a new calculus-based algorithm produces a continuous-diameter solution which is mapped onto a discrete-diameter set. The backtracking algorithm finds the global optimum for all but the largest of cases tested, for which its long runtime makes it an infeasible option. The calculus-based algorithm's discrete-diameter solution produced slightly higher-cost results but was more scalable to larger network cases. Furthermore, the new calculus-based algorithm's continuous-diameter and mapped solutions provided lower and upper bounds, respectively, on the discrete-diameter global optimum cost, where the mapped solutions were typically within one diameter size of the global optimum. The genetic algorithm produced solutions even closer to the global optimum with consistently short run times, although slightly higher solution costs were seen for the larger network cases tested. The results of this study highlight the advantages and weaknesses of each GDWN design method including closeness to the global optimum, the ability to prune the solution space of infeasible and suboptimal candidates without missing the global optimum, and algorithm run time. We also extend an existing closed-form model of Jones (2011) to include minor losses and a more comprehensive two-part cost model, which realistically applies to pipe sizes that span a broad range typical of GDWNs of interest in this work, and for smooth and commercial steel roughness values.
Arsenic in groundwater in the North Carolina Eastern slate belt (Esb): Nash and halifax counties, north carolina

USGS Publications Warehouse

Reid, J.C.; Haven, W.T.; Eudy, D.D.; Milosh, R.M.; Stafford, E.G.

2010-01-01

Naturally occurring arsenic-contaminated groundwater is present within the Eastern Slate Belt (ESB) of North Carolina. Long-term, integrated geologic and geo-chemical investigations havedetermined the presence of arsenic by analyzing precipitates from first and second order streams under base flow conditions. When groundwater discharges into streams, arsenic and other metals are precipitated from solution, due to redox changes between the subsurface and surface environments. Analyses (As, base metals, Fe and Mn) were determined following chemical extraction ofnaturally occurring manganese-iron oxide-coatings, which had precipitated from solution onto stream-bed cobbles. Additionally, artificial redox fronts were produced by placing ceramic tilesin streambeds to collect and analyze oxide precipitates. Thermochemical plots from these data, as well as information from respective stream water measurements (pH and Eh), water sampling, and rock chemical analyses indicate mobile arsenic in predicted stability fields. Initial results show that naturally occurring arsenic-contaminated groundwater is present within the study area. However, the resulting oxidation and pre-cipitation within streams appreciably removes thiscontaminant from surface water solution.
What Can Interfacial Water Molecules Tell Us About Solute Structure?

NASA Astrophysics Data System (ADS)

Willard, Adam

The molecular structure of bulk liquid water reflects a molecular tendency to engage in tetrahedrally coordinated hydrogen bonding. At a solute interface waters preferred three-dimensional hydrogen bonding network must conform to a locally anisotropy interfacial environment. Interfacial water molecules adopt configurations that balance water-solute and water-water interactions. The arrangements of interfacial water molecules, therefore encode information about the effective solute-water interactions. This solute-specific information is difficult to extract, however, because interfacial structure also reflects waters collective response to an anisotropic hydrogen bonding environment. Here I present a methodology for characterizing the molecular-level structure of liquid water interface from simulation data. This method can be used to explore waters static and/or dynamic response to a wide range of chemically and topologically heterogeneous solutes such as proteins.
Fraction of free-base nicotine in fresh smoke particulate matter from the Eclipse "cigarette" by 1H NMR spectroscopy.

PubMed

Pankow, James F; Barsanti, Kelley C; Peyton, David H

2003-01-01

Solution 1H NMR (proton-NMR) spectroscopy was used to measure the distribution of nicotine between its free-base and protonated forms at 20 degrees C in (a) water; (b) glycerin/water mixtures; and (c) puff-averaged "smoke" particulate matter (PM) produced by the Eclipse cigarette, a so-called "harm reduction" cigarette manufactured by R. J. Reynolds (RJR) Tobacco Co. Smoke PM from the Eclipse contains glycerin, water, nicotine, and numerous other components. Smoke PM from the Eclipse yielded a signal for the three N-methyl protons on nicotine at a chemical shift of delta (ppm) = 2.79 relative to a trimethylsilane standard. With alpha fb = fraction of the total liquid nicotine in free-base form, and alpha a = fraction in the acidic, monoprotonated NicH+ form, then alpha a + alpha fb approximately 1. (The diprotonated form of nicotine was assumed negligible.) When the three types of solutions were adjusted so that alpha a approximately 1, the N-methyl protons yielded delta a = 2.82 (Eclipse smoke PM); 2.79 (35% water/65% glycerin); and 2.74 (water). When the solutions were adjusted so that alpha fb approximately 1, the N-methyl protons yielded delta fb = 2.16 (Eclipse smoke PM); 2.13 (35% water/65% glycerin); and 2.10 (water). In all of the solutions, the rate of proton exchange between NicH+ and Nic was fast relative to the 1H-NMR chemical shift difference in hertz. Each solution containing both NicH+ and Nic thus yielded a single N-methyl peak at a delta given by delta = alpha a delta a + alpha fb delta fb so that delta varied linearly between delta a and delta fb. Since alpha fb = (delta a-delta)/(delta a-delta fb), then delta = 2.79 for the unadjusted Eclipse smoke PM indicates alpha fb approximately 0.04. The effective pH of the Eclipse smoke PM at 20 degrees C may then be calculated as pHeff = 8.06 + log[alpha fb/(1-alpha fb)] = 6.69, where 8.06 is the pKa of NicH+ in water at 20 degrees C. The measurements obtained for the puff-averaged Eclipse smoke PM pertain to the chemistry of the smoke PM as it might be initially inhaled at 20 degrees C. Upon inhalation, the volatilization of nicotine and other acid/base active compounds (as well as a warming toward a body temperature of 37 degrees C) will alter the pHeff value of the smoke PM during the time that it resides and ages in the respiratory tract.
Humidity-insensitive water evaporation from molecular complex fluids.

PubMed

Salmon, Jean-Baptiste; Doumenc, Frédéric; Guerrier, Béatrice

2017-09-01

We investigated theoretically water evaporation from concentrated supramolecular mixtures, such as solutions of polymers or amphiphilic molecules, using numerical resolutions of a one-dimensional model based on mass transport equations. Solvent evaporation leads to the formation of a concentrated solute layer at the drying interface, which slows down evaporation in a long-time-scale regime. In this regime, often referred to as the falling rate period, evaporation is dominated by diffusive mass transport within the solution, as already known. However, we demonstrate that, in this regime, the rate of evaporation does not also depend on the ambient humidity for many molecular complex fluids. Using analytical solutions in some limiting cases, we first demonstrate that a sharp decrease of the water chemical activity at high solute concentration leads to evaporation rates which depend weakly on the humidity, as the solute concentration at the drying interface slightly depends on the humidity. However, we also show that a strong decrease of the mutual diffusion coefficient of the solution enhances considerably this effect, leading to nearly independent evaporation rates over a wide range of humidity. The decrease of the mutual diffusion coefficient indeed induces strong concentration gradients at the drying interface, which shield the concentration profiles from humidity variations, except in a very thin region close to the drying interface.
A closed-form solution for steady-state coupled phloem/xylem flow using the Lambert-W function.

PubMed

Hall, A J; Minchin, P E H

2013-12-01

A closed-form solution for steady-state coupled phloem/xylem flow is presented. This incorporates the basic Münch flow model of phloem transport, the cohesion model of xylem flow, and local variation in the xylem water potential and lateral water flow along the transport pathway. Use of the Lambert-W function allows this solution to be obtained under much more general and realistic conditions than has previously been possible. Variation in phloem resistance (i.e. viscosity) with solute concentration, and deviations from the Van't Hoff expression for osmotic potential are included. It is shown that the model predictions match those of the equilibrium solution of a numerical time-dependent model based upon the same mechanistic assumptions. The effect of xylem flow upon phloem flow can readily be calculated, which has not been possible in any previous analytical model. It is also shown how this new analytical solution can handle multiple sources and sinks within a complex architecture, and can describe competition between sinks. The model provides new insights into Münch flow by explicitly including interactions with xylem flow and water potential in the closed-form solution, and is expected to be useful as a component part of larger numerical models of entire plants. © 2013 John Wiley & Sons Ltd.
Co-management of Water, Energy, and Food Systems: Where Are We and What Does it Take for Implementation?

NASA Astrophysics Data System (ADS)

Akhbari, M.

2015-12-01

Water, energy, and food are closely bound in consumption and production patterns. To increase resource efficiency and productivity in a sustainable fashion, co-management of water, energy, and food resources is becoming inevitable. These co-management schemes require implementation of nexus-based approaches, which takes the interconnections of water, energy, and food systems into account and considers that development in one area may have major effects on others. While society, economy and environment are the action areas to implement a nexus approach, finance, governance, infrastructure and technology can create solutions. Existing obstacles in the action areas and challenges associated with creating solutions increase the complexities to develop nexus-based approaches and complicate their implementation. This study, identifies existing social, economic, and environmental obstacles, financial demands and constraints, shortcomings in governance, and infrastructure problems in the United States as the main challenges that need to be overcome. Then, it will be discussed how advanced technology could be employed to facilitate implementation of nexus-based approaches, followed by providing some recommendations to enable institutions to employ new technology, overcome existing obstacles, and address challenges in order to implement nexus-based management approaches.
Low-Temperature, Solution-Processed, Transparent Zinc Oxide-Based Thin-Film Transistors for Sensing Various Solvents

PubMed Central

You, Hsin-Chiang; Wang, Cheng-Jyun

2017-01-01

A low temperature solution-processed thin-film transistor (TFT) using zinc oxide (ZnO) film as an exposed sensing semiconductor channel was fabricated to detect and identify various solution solvents. The TFT devices would offer applications for low-cost, rapid and highly compatible water-soluble detection and could replace conventional silicon field effect transistors (FETs) as bio-sensors. In this work, we demonstrate the utility of the TFT ZnO channel to sense various liquids, such as polar solvents (ethanol), non-polar solvents (toluene) and deionized (DI) water, which were dropped and adsorbed onto the channel. It is discussed how different dielectric constants of polar/non-polar solvents and DI water were associated with various charge transport properties, demonstrating the main detection mechanisms of the thin-film transistor. PMID:28772592
Multiobjective optimization of urban water resources: Moving toward more practical solutions

NASA Astrophysics Data System (ADS)

Mortazavi, Mohammad; Kuczera, George; Cui, Lijie

2012-03-01

The issue of drought security is of paramount importance for cities located in regions subject to severe prolonged droughts. The prospect of "running out of water" for an extended period would threaten the very existence of the city. Managing drought security for an urban water supply is a complex task involving trade-offs between conflicting objectives. In this paper a multiobjective optimization approach for urban water resource planning and operation is developed to overcome practically significant shortcomings identified in previous work. A case study based on the headworks system for Sydney (Australia) demonstrates the approach and highlights the potentially serious shortcomings of Pareto optimal solutions conditioned on short climate records, incomplete decision spaces, and constraints to which system response is sensitive. Where high levels of drought security are required, optimal solutions conditioned on short climate records are flawed. Our approach addresses drought security explicitly by identifying approximate optimal solutions in which the system does not "run dry" in severe droughts with expected return periods up to a nominated (typically large) value. In addition, it is shown that failure to optimize the full mix of interacting operational and infrastructure decisions and to explore the trade-offs associated with sensitive constraints can lead to significantly more costly solutions.

Regional inversion of GRACE data for continental water mass time-variations. Comparison with global hydrology models, classical spherical harmonics and "mascons" solutions

NASA Astrophysics Data System (ADS)

Seoane, L.; Ramillien, G.; Frappart, F.; Biancale, R.; Gratton, S.; Bourgogne, S.

2010-12-01

Time series of 2°-by-2° constrained/unconstrained GRACE geoid solutions have been computed with a 10-day resolution by using a new regional method recently implemented at GRGS (Toulouse, France). This approach uses the dynamical orbit analysis of GRACE Level-1 measurements, and specially accurate along-track KBRR residuals to estimate the continental water mass changes over large geographical regions. For validation, our GRACE-derived regional maps are compared to: (1) the global hydrological model outputs (WGHM, LaD, NOAH), (2) the NASA "mascons" solutions based on spherical harmonics and (3) the global solutions produced by GRGS and CSR, GFZ, JPL filtered with different methodologies (Gaussian, destriped and smoothed, ICA). In this study, we focus on the annual time scale of water mass redistributions occuring in drainage basins like Amazon or Congo. Each 2°-averaged surface element is characterized by its seasonal amplitude and phase. Even if the all sources are expected to provide quite comparable results for the continental water cycle, we suspect the residual differences are from smoothing effects of the spatial constraints included in the "mascons" solutions and the underestimating the seasonal amplitudes by global hydrological models.
In situ study of mass transfer in aqueous solutions under high pressures via Raman spectroscopy: A new method for the determination of diffusion coefficients of methane in water near hydrate formation conditions

USGS Publications Warehouse

Lu, W.J.; Chou, I.-Ming; Burruss, R.C.; Yang, M.Z.

2006-01-01

A new method was developed for in situ study of the diffusive transfer of methane in aqueous solution under high pressures near hydrate formation conditions within an optical capillary cell. Time-dependent Raman spectra of the solution at several different spots along the one-dimensional diffusion path were collected and thus the varying composition profile of the solution was monitored. Diffusion coefficients were estimated by the least squares method based on the variations in methane concentration data in space and time in the cell. The measured diffusion coefficients of methane in water at the liquid (L)-vapor (V) stable region and L-V metastable region are close to previously reported values determined at lower pressure and similar temperature. This in situ monitoring method was demonstrated to be suitable for the study of mass transfer in aqueous solution under high pressure and at various temperature conditions and will be applied to the study of nucleation and dissolution kinetics of methane hydrate in a hydrate-water system where the interaction of methane and water would be more complicated than that presented here for the L-V metastable condition. ?? 2006 Society for Applied Spectroscopy.
Distributed Energy Planning for Climate Resilience

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

Stout, Sherry R; Hotchkiss, Elizabeth L; Day, Megan H

At various levels of government across the United States and globally climate resilient solutions are being adopted and implemented. Solutions vary based on predicted hazards, community context, priorities, complexity, and available resources. Lessons are being learned through the implementation process, which can be replicated regardless of level or type of government entity carrying out the resiliency planning. Through a number of analyses and technical support across the world, NREL has learned key lessons related to resilience planning associated with power generation and water distribution. Distributed energy generation is a large factor in building resilience with clean energy technologies and solutions.more » The technical and policy solutions associated with distributed energy implementation for resilience fall into a few major categories, including spatial diversification, microgrids, water-energy nexus, policy, and redundancy.« less
Studies of quaternary saline lakes-I. Hydrogen isotope fractionation in saline minerals

USGS Publications Warehouse

Matsuo, S.; Friedman, I.; Smith, G.I.

1972-01-01

Borax, gaylussite, nahcolite and trona were synthesized in aqueous solution at temperatures ranging from 8?? to 35??C. Except for borax, deuterium was always depleted in these hydrated minerals relative to the solutions from which they were crystallized. In borax, no significant fractionation was found. The fractionation factor of D H for the trona-water system exhibited a marked temperature dependence. By combining the deuterium contents of trona and the solution from which trona was crystallized, the following thermometer scale was obtained: In ( D H) trona ( D H)water = 1.420 ?? 104 T2 + 23.56 T (1). An attempt to establish a geothermometer based on C13 C12 fractionation between carbonate minerals and carbonate ions in aqueous solution was not successful. ?? 1972.
Screen-printed electrode based electrochemical detector coupled with ionic liquid dispersive liquid-liquid microextraction and microvolume back-extraction for determination of mercury in water samples.

PubMed

Fernández, Elena; Vidal, Lorena; Martín-Yerga, Daniel; Blanco, María del Carmen; Canals, Antonio; Costa-García, Agustín

2015-04-01

A novel approach is presented, whereby gold nanostructured screen-printed carbon electrodes (SPCnAuEs) are combined with in-situ ionic liquid formation dispersive liquid-liquid microextraction (in-situ IL-DLLME) and microvolume back-extraction for the determination of mercury in water samples. In-situ IL-DLLME is based on a simple metathesis reaction between a water-miscible IL and a salt to form a water-immiscible IL into sample solution. Mercury complex with ammonium pyrrolidinedithiocarbamate is extracted from sample solution into the water-immiscible IL formed in-situ. Then, an ultrasound-assisted procedure is employed to back-extract the mercury into 10 µL of a 4 M HCl aqueous solution, which is finally analyzed using SPCnAuEs. Sample preparation methodology was optimized using a multivariate optimization strategy. Under optimized conditions, a linear range between 0.5 and 10 µg L(-1) was obtained with a correlation coefficient of 0.997 for six calibration points. The limit of detection obtained was 0.2 µg L(-1), which is lower than the threshold value established by the Environmental Protection Agency and European Union (i.e., 2 µg L(-1) and 1 µg L(-1), respectively). The repeatability of the proposed method was evaluated at two different spiking levels (3 and 10 µg L(-1)) and a coefficient of variation of 13% was obtained in both cases. The performance of the proposed methodology was evaluated in real-world water samples including tap water, bottled water, river water and industrial wastewater. Relative recoveries between 95% and 108% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.
Dielectric and structural properties of aqueous nonpolar solute mixtures.

PubMed

Shvab, I; Sadus, Richard J

2012-09-28

The dielectric properties and molecular structure of water mixtures with different nonpolar solutes (methane and noble gases) are studied using molecular dynamics. The water-water, water-solute, and solute-solute interactions are calculated using the combination of a polarizable potential [J. Li, Z. Zhou, and R. J. Sadus, J. Chem. Phys. 127, 154509 (2007)] for water plus the Lennard-Jones potential. The effect of solute size and concentration on the solubility of the system, hydrogen bonding, dielectric constant, and dipole moment are investigated over a temperature range of 278-750 K and solute percentage mole fractions up to 30%. Solute particles affect the structure of water, resulting in the compression of oxygen-oxygen and oxygen-hydrogen radial distribution functions. The influence of the solute extends both to relatively low concentrations and high temperatures. The coordination numbers of aqueous solutions of the nonpolar solutes appear to be proportional to the size of the solute particles. Our study shows the destructive influence of the nonpolar solute on both the tetrahedral water structure and hydrogen bond formation at solute concentrations greater than 30%. The presence of nonpolar particles typically decreases both the dielectric constant and dipole moment. The decrease of dielectric constant and water dipole moment is directly proportional to the solute concentration and temperature.
Ion-Specific Nutrient Management in Closed Systems: The Necessity for Ion-Selective Sensors in Terrestrial and Space-Based Agriculture and Water Management Systems

PubMed Central

Bamsey, Matthew; Graham, Thomas; Thompson, Cody; Berinstain, Alain; Scott, Alan; Dixon, Michael

2012-01-01

The ability to monitor and control plant nutrient ions in fertigation solutions, on an ion-specific basis, is critical to the future of controlled environment agriculture crop production, be it in traditional terrestrial settings (e.g., greenhouse crop production) or as a component of bioregenerative life support systems for long duration space exploration. Several technologies are currently available that can provide the required measurement of ion-specific activities in solution. The greenhouse sector has invested in research examining the potential of a number of these technologies to meet the industry's demanding requirements, and although no ideal solution yet exists for on-line measurement, growers do utilize technologies such as high-performance liquid chromatography to provide off-line measurements. An analogous situation exists on the International Space Station where, technological solutions are sought, but currently on-orbit water quality monitoring is considerably restricted. This paper examines the specific advantages that on-line ion-selective sensors could provide to plant production systems both terrestrially and when utilized in space-based biological life support systems and how similar technologies could be applied to nominal on-orbit water quality monitoring. A historical development and technical review of the various ion-selective monitoring technologies is provided. PMID:23201999
Ion-specific nutrient management in closed systems: the necessity for ion-selective sensors in terrestrial and space-based agriculture and water management systems.

PubMed

Bamsey, Matthew; Graham, Thomas; Thompson, Cody; Berinstain, Alain; Scott, Alan; Dixon, Michael

2012-10-01

The ability to monitor and control plant nutrient ions in fertigation solutions, on an ion-specific basis, is critical to the future of controlled environment agriculture crop production, be it in traditional terrestrial settings (e.g., greenhouse crop production) or as a component of bioregenerative life support systems for long duration space exploration. Several technologies are currently available that can provide the required measurement of ion-specific activities in solution. The greenhouse sector has invested in research examining the potential of a number of these technologies to meet the industry's demanding requirements, and although no ideal solution yet exists for on-line measurement, growers do utilize technologies such as high-performance liquid chromatography to provide off-line measurements. An analogous situation exists on the International Space Station where, technological solutions are sought, but currently on-orbit water quality monitoring is considerably restricted. This paper examines the specific advantages that on-line ion-selective sensors could provide to plant production systems both terrestrially and when utilized in space-based biological life support systems and how similar technologies could be applied to nominal on-orbit water quality monitoring. A historical development and technical review of the various ion-selective monitoring technologies is provided.
Ice nucleation activity of silicates and aluminosilicates in pure water and aqueous solutions - Part 1: The K-feldspar microcline

NASA Astrophysics Data System (ADS)

Kumar, Anand; Marcolli, Claudia; Luo, Beiping; Peter, Thomas

2018-05-01

Potassium-containing feldspars (K-feldspars) have been considered as key mineral dusts for ice nucleation (IN) in mixed-phase clouds. To investigate the effect of solutes on their IN efficiency, we performed immersion freezing experiments with the K-feldspar microcline, which is highly IN active. Freezing of emulsified droplets with microcline suspended in aqueous solutions of NH3, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl, with solute concentrations corresponding to water activities aw = 0.9-1.0, were investigated by means of a differential scanning calorimeter (DSC). The measured heterogeneous IN onset temperatures, Thet(aw), deviate strongly from ThetΔawhet(aw), the values calculated from the water-activity-based approach (where ThetΔawhet(aw) = Tmelt(aw + Δawhet) with a constant offset Δawhet with respect to the ice melting point curve). Surprisingly, for very dilute solutions of NH3 and NH4+ salts (molalities ≲1 mol kg-1 corresponding to aw ≳ 0.96), we find IN temperatures raised by up to 4.5 K above the onset freezing temperature of microcline in pure water (Thet(aw = 1)) and 5.5 K above ThetΔawhet(aw), revealing NH3 and NH4+ to significantly enhance the IN of the microcline surface. Conversely, more concentrated NH3 and NH4+ solutions show a depression of the onset temperature below ThetΔawhet(aw) by as much as 13.5 K caused by a decline in IN ability accompanied with a reduction in the volume fraction of water frozen heterogeneously. All salt solutions not containing NH4+ as cation exhibit nucleation temperatures Thet(aw) < ThetΔawhet(aw) even at very small solute concentrations. In all these cases, the heterogeneous freezing peak displays a decrease as solute concentration increases. This deviation from Δawhet = const. indicates specific chemical interactions between particular solutes and the microcline surface not captured by the water-activity-based approach. One such interaction is the exchange of K+ available on the microcline surface with externally added cations (e.g., NH4+). However, the presence of a similar increase in IN efficiency in dilute ammonia solutions indicates that the cation exchange cannot explain the increase in IN temperatures. Instead, we hypothesize that NH3 molecules hydrogen bonded on the microcline surface form an ice-like overlayer, which provides hydrogen bonding favorable for ice to nucleate on, thus enhancing both the freezing temperatures and the heterogeneously frozen fraction in dilute NH3 and NH4+ solutions. Moreover, we show that aging of microcline in concentrated solutions over several days does not impair IN efficiency permanently in case of near-neutral solutions since most of it recovers when aged particles are resuspended in pure water. In contrast, exposure to severe acidity (pH ≲1.2) or alkalinity (pH ≳11.7) damages the microcline surface, hampering or even destroying the IN efficiency irreversibly. Implications for IN in airborne dust containing microcline might be multifold, ranging from a reduction of immersion freezing when exposed to dry, cold and acidic conditions to a 5 K enhancement during condensation freezing when microcline particles experience high humidity (aw≳0.96) at warm (252-257 K) and NH3/NH4+-rich conditions.
Diffusion of aqueous solutions of ionic, zwitterionic, and polar solutes

NASA Astrophysics Data System (ADS)

Teng, Xiaojing; Huang, Qi; Dharmawardhana, Chamila Chathuranga; Ichiye, Toshiko

2018-06-01

The properties of aqueous solutions of ionic, zwitterionic, and polar solutes are of interest to many fields. For instance, one of the many anomalous properties of aqueous solutions is the behavior of water diffusion in different monovalent salt solutions. In addition, solutes can affect the stabilities of macromolecules such as proteins in aqueous solution. Here, the diffusivities of aqueous solutions of sodium chloride, potassium chloride, tri-methylamine oxide (TMAO), urea, and TMAO-urea are examined in molecular dynamics simulations. The decrease in the diffusivity of water with the concentration of simple ions and urea can be described by a simple model in which the water molecules hydrogen bonded to the solutes are considered to diffuse at the same rate as the solutes, while the remainder of the water molecules are considered to be bulk and diffuse at almost the same rate as pure water. On the other hand, the decrease in the diffusivity of water with the concentration of TMAO is apparently affected by a decrease in the diffusion rate of the bulk water molecules in addition to the decrease due to the water molecules hydrogen bonded to TMAO. In other words, TMAO enhances the viscosity of water, while urea barely affects it. Overall, this separation of water molecules into those that are hydrogen bonded to solute and those that are bulk can provide a useful means of understanding the short- and long-range effects of solutes on water.
Configurations of base-pair complexes in solutions. [nucleotide chemistry

NASA Technical Reports Server (NTRS)

Egan, J. T.; Nir, S.; Rein, R.; Macelroy, R.

1978-01-01

A theoretical search for the most stable conformations (i.e., stacked or hydrogen bonded) of the base pairs A-U and G-C in water, CCl4, and CHCl3 solutions is presented. The calculations of free energies indicate a significant role of the solvent in determining the conformations of the base-pair complexes. The application of the continuum method yields preferred conformations in good agreement with experiment. Results of the calculations with this method emphasize the importance of both the electrostatic interactions between the two bases in a complex, and the dipolar interaction of the complex with the entire medium. In calculations with the solvation shell method, the last term, i.e., dipolar interaction of the complex with the entire medium, was added. With this modification the prediction of the solvation shell model agrees both with the continuum model and with experiment, i.e., in water the stacked conformation of the bases is preferred.
Lowering the Percolation Threshold of Conductive Composites Using Particulate Polymer Microstructure

NASA Astrophysics Data System (ADS)

Grunlan, Jaime; Gerberich, William; Francis, Lorraine

2000-03-01

In an effort to lower the percolation threshold of carbon black-filled polymer composites, various polymer microstructures were examined. Composites were prepared using polyvinyl acetate (PVAc) latex, PVAc water-dispersible powder and polyvinylpyrrolidone (PVP) solution as the matrix starting material. Composites prepared using the particulate microstructures showed a significantly lowered percolation threshold relative to an equivalently prepared composite using the PVP solution. The PVAc latex-based composites has a percolation threshold of 3 volthe PVP solution-based composite yielded a percolation threshold near 15 voloccupied by polymer particles, the particulate matrix-based composites create a segregated CB network at low filler concentration.
Photoacoustic measurement for glucose solution concentration based on tunable pulsed laser induced ultrasound

NASA Astrophysics Data System (ADS)

Ren, Zhong; Liu, Guodong; Huang, Zhen; Zhao, Dengji

2012-12-01

Noninvasive measurement of blood glucose concentration (BGC) has become a research hotspot. BGC measurement based on photoacoustic spectroscopy (PAS) was employed to detect the photoacoustic (PA) signal of blood glucose due to the advantages of avoiding the disturbance of optical scattering. In this paper, a set of custom-built BGC measurement system based on tunable optical parametric oscillator (OPO) pulsed laser and ultrasonic transducer was established to test the PA response effect of the glucose solution. In the experiments, we successfully acquired the time resolved PA signals of distilled water and glucose aqueous solution, and the PA peak-to-peak values(PPV) were gotten under the condition of excitated pulsed laser with changed wavelength from 1340nm to 2200nm by increasing interval of 10nm, the optimal characteristic wavelengths of distilled water and glucose solution were determined. Finally, to get the concentration prediction error, we used the linear fitting of ordinary least square (OLS) algorithm to fit the PPV of 1510nm, and we got the predicted concentration error was about 0.69mmol/L via the fitted linear equation. So, this system and scheme have some values in the research of noninvasive BGC measurement.
[Determination of estrogen residues in drinking water by on-line solid phase extraction based on sol-gel technique coupled with high performance liquid chromatography].

PubMed

Li, Longfei; Su, Min; Shi, Xiaolei; Wang, Yana; Wang, Minmin; He, Jinxing

2014-02-01

A method for the determination of diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DS) residues in drinking water was established by on-line solid phase extraction (SPE) coupled with high performance liquid chromatography (HPLC). The material synthesized on the base of sol-gel technology was employed as adsorbent. This material was prepared using 3-aminopropyltriethoxysilane (APTES) as the functional monomer, tetraethoxysilane (TEOS) as the crosslinking agent, and acetic acid as the initiator. The synthesized adsorbent showed outstanding property for the estrogen extraction. The estrogen can be caught effectively from water samples and the extraction can be achieved rapidly. Some important parameters, such as pH of sample solution, eluent solvents, loading flow rate, which might influence extraction efficiency, were optimized. The results indicated that the limit of detection (S/N = 3) of the developed method could reach 0.07-0.13 microg/L under the conditions of pH 7.0 of sample solution, methanol and 1% (v/v) acetic acid aqueous solution as the eluent solvent and the loading flow rate of 2 mL/min. The recoveries of the three estrogens from the water samples at three spiked levels ranged from 82.31% to 99.43% with RSD of 1.61%-7.15%. The method was simple, rapid, and suitable to detect the trace residues of estrogens in drinking water.
Enhanced intelligent water drops algorithm for multi-depot vehicle routing problem

PubMed Central

Akutsah, Francis; Olusanya, Micheal O.; Adewumi, Aderemi O.

2018-01-01

The intelligent water drop algorithm is a swarm-based metaheuristic algorithm, inspired by the characteristics of water drops in the river and the environmental changes resulting from the action of the flowing river. Since its appearance as an alternative stochastic optimization method, the algorithm has found applications in solving a wide range of combinatorial and functional optimization problems. This paper presents an improved intelligent water drop algorithm for solving multi-depot vehicle routing problems. A simulated annealing algorithm was introduced into the proposed algorithm as a local search metaheuristic to prevent the intelligent water drop algorithm from getting trapped into local minima and also improve its solution quality. In addition, some of the potential problematic issues associated with using simulated annealing that include high computational runtime and exponential calculation of the probability of acceptance criteria, are investigated. The exponential calculation of the probability of acceptance criteria for the simulated annealing based techniques is computationally expensive. Therefore, in order to maximize the performance of the intelligent water drop algorithm using simulated annealing, a better way of calculating the probability of acceptance criteria is considered. The performance of the proposed hybrid algorithm is evaluated by using 33 standard test problems, with the results obtained compared with the solutions offered by four well-known techniques from the subject literature. Experimental results and statistical tests show that the new method possesses outstanding performance in terms of solution quality and runtime consumed. In addition, the proposed algorithm is suitable for solving large-scale problems. PMID:29554662
Enhanced intelligent water drops algorithm for multi-depot vehicle routing problem.

PubMed

Ezugwu, Absalom E; Akutsah, Francis; Olusanya, Micheal O; Adewumi, Aderemi O

2018-01-01

The intelligent water drop algorithm is a swarm-based metaheuristic algorithm, inspired by the characteristics of water drops in the river and the environmental changes resulting from the action of the flowing river. Since its appearance as an alternative stochastic optimization method, the algorithm has found applications in solving a wide range of combinatorial and functional optimization problems. This paper presents an improved intelligent water drop algorithm for solving multi-depot vehicle routing problems. A simulated annealing algorithm was introduced into the proposed algorithm as a local search metaheuristic to prevent the intelligent water drop algorithm from getting trapped into local minima and also improve its solution quality. In addition, some of the potential problematic issues associated with using simulated annealing that include high computational runtime and exponential calculation of the probability of acceptance criteria, are investigated. The exponential calculation of the probability of acceptance criteria for the simulated annealing based techniques is computationally expensive. Therefore, in order to maximize the performance of the intelligent water drop algorithm using simulated annealing, a better way of calculating the probability of acceptance criteria is considered. The performance of the proposed hybrid algorithm is evaluated by using 33 standard test problems, with the results obtained compared with the solutions offered by four well-known techniques from the subject literature. Experimental results and statistical tests show that the new method possesses outstanding performance in terms of solution quality and runtime consumed. In addition, the proposed algorithm is suitable for solving large-scale problems.
Partition Coefficients of Organics between Water and Carbon Dioxide Revisited: Correlation with Solute Molecular Descriptors and Solvent Cohesive Properties.

PubMed

Roth, Michal

2016-12-06

High-pressure phase behavior of systems containing water, carbon dioxide and organics has been important in several environment- and energy-related fields including carbon capture and storage, CO 2 sequestration and CO 2 -assisted enhanced oil recovery. Here, partition coefficients (K-factors) of organic solutes between water and supercritical carbon dioxide have been correlated with extended linear solvation energy relationships (LSERs). In addition to the Abraham molecular descriptors of the solutes, the explanatory variables also include the logarithm of solute vapor pressure, the solubility parameters of carbon dioxide and water, and the internal pressure of water. This is the first attempt to include also the properties of water as explanatory variables in LSER correlations of K-factor data in CO 2 -water-organic systems. Increasing values of the solute hydrogen bond acidity, the solute hydrogen bond basicity, the solute dipolarity/polarizability, the internal pressure of water and the solubility parameter of water all tend to reduce the K-factor, that is, to favor the solute partitioning to the water-rich phase. On the contrary, increasing values of the solute characteristic volume, the solute vapor pressure and the solubility parameter of CO 2 tend to raise the K-factor, that is, to favor the solute partitioning to the CO 2 -rich phase.
MODFLOW/MT3DMS-based simulation of variable-density ground water flow and transport

USGS Publications Warehouse

Langevin, C.D.; Guo, W.

2006-01-01

This paper presents an approach for coupling MODFLOW and MT3DMS for the simulation of variable-density ground water flow. MODFLOW routines were modified to solve a variable-density form of the ground water flow equation in which the density terms are calculated using an equation of state and the simulated MT3DMS solute concentrations. Changes to the MODFLOW and MT3DMS input files were kept to a minimum, and thus existing data files and data files created with most pre- and postprocessors can be used directly with the SEAWAT code. The approach was tested by simulating the Henry problem and two of the saltpool laboratory experiments (low- and high-density cases). For the Henry problem, the simulated results compared well with the steady-state semianalytic solution and also the transient isochlor movement as simulated by a finite-element model. For the saltpool problem, the simulated breakthrough curves compared better with the laboratory measurements for the low-density case than for the high-density case but showed good agreement with the measured salinity isosurfaces for both cases. Results from the test cases presented here indicate that the MODFLOW/MT3DMS approach provides accurate solutions for problems involving variable-density ground water flow and solute transport. ?? 2006 National Ground Water Association.
Studies on urine treatment by biological purification using Azolla and UV photocatalytic oxidation

NASA Astrophysics Data System (ADS)

Liu, Xiaofeng; Chen, Min; Bian, Zuliang; Liu, Chung-Chu

The amount of water consumed in space station operations is very large. In order to reduce the amount of water which must be resupplied from Earth, the space station needs to resolve the problems of water supply. For this reason, the recovery, regeneration and utilization of urine of astronauts are of key importance. Many investigations on this subject have been reported. Our research is based on biological absorption and, purification using UV photocatalytic oxidation techniques to achieve comprehensive treatment for urine. In the treatment apparatus we created, the urine solution is used as part of the nutrient solution for the biological components in our bioregenerative life support system. After being absorbed, the nutrients from the urine were then decomposed, metabolized and purified which creates a favorable condition for the follow-up oxidation treatment by UV photocatalytic oxidation. After these two processes, the treated urine solution reached Chinese national standards for drinking water quality (GB5749-1985).
Properties of a Novel Ion-Exchange Film

NASA Technical Reports Server (NTRS)

Street, Kenneth W.; Hill, Carol M.; Philipp, Warren H.; Tanner, Stephen P.; Gorse, Joseph; Lusk, Amy; Taylor, Jason; Dickens, Jason

2002-01-01

A new ion-exchange material (based on polyacrylic acid) and some of its analytical applications have been reported. This paper contains data on the ion-exchange properties of the film form of the material and its potential application to the decontamination of waste water and drinking water. The film has a high exchange capacity of 5 to 6 meq/g and a pK(sub a) of 5.7. The calcium form is the most effective for removing metal ions from solution, and the optimum pH range is between 5 and 7. The exchange rates are slower for the film than for bead and powder forms of the ion-exchange material; otherwise, the properties are similar. The film is effective when hard water solutions are employed and also when metal ions are in the complex matrix of waste water from electroplating. The film can be used in flow systems having a flow channel large enough to allow passage of turbid solutions.

Rapid measurement of 89,90Sr radioactivity in rinse water.

PubMed

Masashi, Takada; Hiroko, Enomoto; Toshikazu, Suzuki

2013-03-01

Rapid measurement of radioactivity from Sr in aqueous solutions is performed using a technique combining a strontium rad disk and a picobeta spectrometer. Identification of Sr radionuclides is accomplished in as little as 90 min in a radiation-tainted solution that contains more highly radioactive cesium. It is possible to perform triage by assessing skin exposure doses in this short time. This simple technique could be used in mobile laboratories. Sr having 1 Bq radioactivities are measured in 10 kBq Cs in aqueous solution. The radioactivity contained in rinse water used to decontaminate the feet of workers who stepped into highly contaminated water in the basement of the turbine building of Unit 3 at the Fukushima Daiichi nuclear power station was measured. The amount of Sr radioactivity in rinse water using the authors' rapid measurement technique (0.29 Bq mL) and a traditional method agree well, with 3.6% difference. Based on this agreement, this technique is confirmed to be useful for rapid measurement of Sr radioactivities.
Properties of a Novel Ion-Exchange Film

NASA Technical Reports Server (NTRS)

Street, Kenneth W.; Hill, Carol M.; Philipp, Warren H.; Tanner, Stephen P.; Gorse, Joseph; Lusk, Amy; Taylor, Jason; Dickens, Jason

2004-01-01

A new ion-exchange material (based on polyacrylic acid) and some of its analytical applications have been reported. This paper contains data on the ion-exchange properties of the film form of the material and its potential application to the decontamination of waste water and drinking water. The film has a high exchange capacity of 5 to 6 meq/g and a pK(sub a) of 5.7. The calcium form is the most effective for removing metal ions from solution, and the optimum pH range is between 5 and 7. The exchange rates are slower for the film than for bead and powder forms of the ion-exchange material; otherwise, the properties are similar. The film is effective when hard water solutions are employed and also when metal ions are in the complex matrix of waste water from electroplating. The film can be used in flow systems having a flow channel large enough to allow passage of turbid solutions.
One-Dimensional Transport with Equilibrium Chemistry (OTEQ) - A Reactive Transport Model for Streams and Rivers

USGS Publications Warehouse

Runkel, Robert L.

2010-01-01

OTEQ is a mathematical simulation model used to characterize the fate and transport of waterborne solutes in streams and rivers. The model is formed by coupling a solute transport model with a chemical equilibrium submodel. The solute transport model is based on OTIS, a model that considers the physical processes of advection, dispersion, lateral inflow, and transient storage. The equilibrium submodel is based on MINTEQ, a model that considers the speciation and complexation of aqueous species, acid-base reactions, precipitation/dissolution, and sorption. Within OTEQ, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (waterborne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach. The model's ability to simulate pH, precipitation/dissolution, and pH-dependent sorption provides a means of evaluating the complex interactions between instream chemistry and hydrologic transport at the field scale. This report details the development and application of OTEQ. Sections of the report describe model theory, input/output specifications, model applications, and installation instructions. OTEQ may be obtained over the Internet at http://water.usgs.gov/software/OTEQ.
A water-based topical Chinese traditional medicine (Zicao) for wound healing developed using 2-hydroxypropyl-β-cyclodextrin.

PubMed

Chen Chen, Ta; Yu, Song-Cu; Hsu, Chin-Mu; Tsai, Fuu-Jen; Tsai, Yuhsin

2018-05-01

Zicao is a traditional Chinese herbal medicine that has been used for the topical treatment of wounds in the form of oil-based ointment for several hundred years. To overcome the disadvantages of oil-based ointment such as irritation, discomfort, and difficulty in cleaning, this study developed a water-based topical formulation of Zicao. An ethanol extract of Zicao was included in 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) to form a water-soluble Zicao-HP-β-CD complex. The formation of the Zicao-HP-β-CD complex was determined using LC-MS, 1 H NMR, ROSEY, and solubility analysis. The bioactivity of Zicao-HP-β-CD complex in aqueous solution was evaluated using cellular uptake in vitro and experimental excision wounds in vivo. The LC-MS, 1 H NMR, ROESY, and solubility analyses results show that Zicao extract was successfully included by the HP-β-CD. The results of the cellular uptake in vitro and wound healing in vivo suggest that the effect of Zicao was enhanced following the formation of the Zicao-HP-β-CD complex. Therefore, we concluded that complexation with HP-β-CD might provide a potential method for developing an effective water-based topical solution of Zicao. Copyright © 2018 Elsevier B.V. All rights reserved.
Combining Interactive Infrastructure Modeling and Evolutionary Algorithm Optimization for Sustainable Water Resources Design

NASA Astrophysics Data System (ADS)

Smith, R.; Kasprzyk, J. R.; Zagona, E. A.

2013-12-01

Population growth and climate change, combined with difficulties in building new infrastructure, motivate portfolio-based solutions to ensuring sufficient water supply. Powerful simulation models with graphical user interfaces (GUI) are often used to evaluate infrastructure portfolios; these GUI based models require manual modification of the system parameters, such as reservoir operation rules, water transfer schemes, or system capacities. Multiobjective evolutionary algorithm (MOEA) based optimization can be employed to balance multiple objectives and automatically suggest designs for infrastructure systems, but MOEA based decision support typically uses a fixed problem formulation (i.e., a single set of objectives, decisions, and constraints). This presentation suggests a dynamic framework for linking GUI-based infrastructure models with MOEA search. The framework begins with an initial formulation which is solved using a MOEA. Then, stakeholders can interact with candidate solutions, viewing their properties in the GUI model. This is followed by changes in the formulation which represent users' evolving understanding of exigent system properties. Our case study is built using RiverWare, an object-oriented, data-centered model that facilitates the representation of a diverse array of water resources systems. Results suggest that assumptions within the initial MOEA search are violated after investigating tradeoffs and reveal how formulations should be modified to better capture stakeholders' preferences.
Water-Rich Fluid Material Containing Orderly Condensed Proteins.

PubMed

Nojima, Tatsuya; Iyoda, Tomokazu

2017-01-24

A fluid material with high protein content (120-310 mg mL -1 ) was formed through the ordered self-assembly of native proteins segregated from water. This material is instantly prepared by the simple mixing of a protein solution with anionic and cationic surfactants. By changing the ratio of the surfactants based on the electrostatic characteristics of the target protein, we observed that the surfactants could function as a versatile molecular glue for protein assembly. Moreover, these protein assemblies could be disassembled back into an aqueous solution depending on the salt conditions. Owing to the water-retaining properties of the hydrophilic part of surfactants, the proteins in this material are in a water-rich environment, which maintains their native structure and function. The inclusion of water also provides functional extensibility to this material, as demonstrated by the preparation of an enzymatically active gel. We anticipate that the unique features of this material will permit the use of proteins not only in solution but also as elements of integrated functionalized materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Evaluation of appropriate technologies for grey water treatments and reuses.

PubMed

Li, Fangyue; Wichmann, Knut; Otterpohl, Ralf

2009-01-01

As water is becoming a rare resource, the onsite reuse and recycling of grey water is practiced in many countries as a sustainable solution to reduce the overall urban water demand. However, the lack of appropriate water quality standards or guidelines has hampered the appropriate grey water reuses. Based on literature review, a non-potable urban grey water treatment and reuse scheme is proposed and the treatment alternatives for grey water reuse are evaluated according to the grey water characteristics, the proposed standards and economical feasibility.
The inverse Numerical Computer Program FLUX-BOT for estimating Vertical Water Fluxes from Temperature Time-Series.

NASA Astrophysics Data System (ADS)

Trauth, N.; Schmidt, C.; Munz, M.

2016-12-01

Heat as a natural tracer to quantify water fluxes between groundwater and surface water has evolved to a standard hydrological method. Typically, time series of temperatures in the surface water and in the sediment are observed and are subsequently evaluated by a vertical 1D representation of heat transport by advection and dispersion. Several analytical solutions as well as their implementation into user-friendly software exist in order to estimate water fluxes from the observed temperatures. Analytical solutions can be easily implemented but assumptions on the boundary conditions have to be made a priori, e.g. sinusoidal upper temperature boundary. Numerical models offer more flexibility and can handle temperature data which is characterized by irregular variations such as storm-event induced temperature changes and thus cannot readily be incorporated in analytical solutions. This also reduced the effort of data preprocessing such as the extraction of the diurnal temperature variation. We developed a software to estimate water FLUXes Based On Temperatures- FLUX-BOT. FLUX-BOT is a numerical code written in MATLAB which is intended to calculate vertical water fluxes in saturated sediments, based on the inversion of measured temperature time series observed at multiple depths. It applies a cell-centered Crank-Nicolson implicit finite difference scheme to solve the one-dimensional heat advection-conduction equation. Besides its core inverse numerical routines, FLUX-BOT includes functions visualizing the results and functions for performing uncertainty analysis. We provide applications of FLUX-BOT to generic as well as to measured temperature data to demonstrate its performance.
Analytical approximation and numerical simulations for periodic travelling water waves

NASA Astrophysics Data System (ADS)

Kalimeris, Konstantinos

2017-12-01

We present recent analytical and numerical results for two-dimensional periodic travelling water waves with constant vorticity. The analytical approach is based on novel asymptotic expansions. We obtain numerical results in two different ways: the first is based on the solution of a constrained optimization problem, and the second is realized as a numerical continuation algorithm. Both methods are applied on some examples of non-constant vorticity. This article is part of the theme issue 'Nonlinear water waves'.
Investigation of melamine derived quaternary as ammonium salt potential shale inhibitor

NASA Astrophysics Data System (ADS)

Yu, Hongjiang; Hu, Weimin; Guo, Gang; Huang, Lei; Li, Lili; Gu, Xuefan; Zhang, Zhifang; Zhang, Jie; Chen, Gang

2017-06-01

Melamine, sodium chloroacetate and sodium hydroxide were used as raw materials to synthesize a kind of neutral quaternary ammonium salt (NQAS) as potential clay swelling inhibitor and water-based drilling fluid additive, and the reaction conditions were screened based on the linear expansion rate of bentonite. The inhibitive properties of NQASs were investigated by various methods, including montmorillonite (MMT) linear expansion test, mud ball immersing test, particle distribution measurement, thermogravimetric analysis and scanning electron microscopy etc. The results indicate that NQAS can inhibit expansion and dispersion of clay in water effectively. At the same condition, the bentonite linear expansion rate in NQAS-6 solution is much lower than those of others, and the hydration expansion degree of the mud ball in 0.5% NQAS-6 solution is appreciably weaker than the control test. The compatibility test indicates NQAS-6 could be compatible with the conventional additives in water-based drilling fluids, and the temperature resistance of modified starch was improved effectively. Meanwhile, the inhibitive mechanism was discussed through the particle distribution measurement.
Compact Apparatus Grows Protein Crystals

NASA Technical Reports Server (NTRS)

Bugg, Charles E.; Delucas, Lawrence J.; Suddath, Fred L.; Snyder, Robert S.; Herren, Blair J.; Carter, Daniel C.; Yost, Vaughn H.

1989-01-01

Laboratory apparatus provides delicately balanced combination of materials and chemical conditions for growth of protein crystals. Apparatus and technique for growth based on hanging-drop method for crystallization of macromolecules. Includes pair of syringes with ganged plungers. One syringe contains protein solution; other contains precipitating-agent solution. Syringes intrude into cavity lined with porous reservoir material saturated with 1 mL or more of similar precipitating-agent solution. Prior to activation, ends of syringes plugged to prevent transport of water vapor among three solutions.
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
From the paddle to the beach - A Boussinesq shallow water numerical wave tank based on Madsen and Sørensen's equations

NASA Astrophysics Data System (ADS)

Orszaghova, Jana; Borthwick, Alistair G. L.; Taylor, Paul H.

2012-01-01

This article describes a one-dimensional numerical model of a shallow-water flume with an in-built piston paddle moving boundary wavemaker. The model is based on a set of enhanced Boussinesq equations and the nonlinear shallow water equations. Wave breaking is described approximately, by locally switching to the nonlinear shallow water equations when a critical wave steepness is reached. The moving shoreline is calculated as part of the solution. The piston paddle wavemaker operates on a movable grid, which is Lagrangian on the paddle face and Eulerian away from the paddle. The governing equations are, however, evolved on a fixed mapped grid, and the newly calculated solution is transformed back onto the moving grid via a domain mapping technique. Validation test results are compared against analytical solutions, confirming correct discretisation of the governing equations, wave generation via the numerical paddle, and movement of the wet/dry front. Simulations are presented that reproduce laboratory experiments of wave runup on a plane beach and wave overtopping of a laboratory seawall, involving solitary waves and compact wave groups. In practice, the numerical model is suitable for simulating the propagation of weakly dispersive waves and can additionally model any associated inundation, overtopping or inland flooding within the same simulation.
A semi-analytical solution for slug tests in an unconfined aquifer considering unsaturated flow

NASA Astrophysics Data System (ADS)

Sun, Hongbing

2016-01-01

A semi-analytical solution considering the vertical unsaturated flow is developed for groundwater flow in response to a slug test in an unconfined aquifer in Laplace space. The new solution incorporates the effects of partial penetrating, anisotropy, vertical unsaturated flow, and a moving water table boundary. Compared to the Kansas Geological Survey (KGS) model, the new solution can significantly improve the fittings of the modeled to the measured hydraulic heads at the late stage of slug tests in an unconfined aquifer, particularly when the slug well has a partially submerged screen and moisture drainage above the water table is significant. The radial hydraulic conductivities estimated with the new solution are comparable to those from the KGS, Bouwer and Rice, and Hvorslev methods. In addition, the new solution also can be used to examine the vertical conductivity, specific storage, specific yield, and the moisture retention parameters in an unconfined aquifer based on slug test data.
RDX in Plant Tissue: Leading to Humification in Surface Soils

DTIC Science & Technology

2013-01-01

enzymatic activities could accel- erate the degradation of RDX once taken up from an aqueous solution . Plant tissue with higher chlorophyll content was found...whereas GSH inhibited it. Photo-induced degrada- tion of TNT occurs at approximately the same rate in extract-based solution . The results indi- cate...RDX-water solution taken up by each plant species................................. 10 Figure 3. Pigmentation patterns of all coleus used
Organic ion association in aqueous phase and ab initio-based force fields: The case of carboxylate/ammonium salts

NASA Astrophysics Data System (ADS)

Houriez, Céline; Vallet, Valérie; Réal, Florent; Meot-Ner Mautner, Michael; Masella, Michel

2017-10-01

We performed molecular dynamics simulations of carboxylate/methylated ammonium ion pairs solvated in bulk water and of carboxylate/methylated ammonium salt solutions at ambient conditions using an ab initio-based polarizable force field whose parameters are assigned to reproduce only high end quantum computations, at the Møller-Plesset second-order perturbation theory/complete basis set limit level, regarding single ions and ion pairs as isolated and micro-hydrated in gas phase. Our results agree with the available experimental results regarding carboxylate/ammonium salt solutions. For instance, our force field approach predicts the percentage of acetate associated with ammonium ions in CH3 COO-/CH3 NH3+ solutions at the 0.2-0.8M concentration scale to range from 14% to 35%, in line with the estimates computed from the experimental ion association constant in liquid water. Moreover our simulations predict the number of water molecules released from the ion first hydration shell to the bulk upon ion association to be about 2.0 ± 0.6 molecules for acetate/protonated amine ion pairs, 3.1 ± 1.5 molecules for the HCOO-/NH4+ pair and 3.3 ± 1.2 molecules for the CH3COO-/(CH3)4N+ pair. For protonated amine-based ion pairs, these values are in line with experiment for alkali/halide pairs solvated in bulk water. All these results demonstrate the promising feature of ab initio-based force fields, i.e., their capacity in accurately modeling chemical systems that cannot be readily investigated using available experimental techniques.
Influence of Water Solute Exposure on the Chemical Evolution and Rheological Properties of Asphalt.

PubMed

Pang, Ling; Zhang, Xuemei; Wu, Shaopeng; Ye, Yong; Li, Yuanyuan

2018-06-11

The properties of asphalt pavement are damaged under the effects of moisture. The pH value and salt concentration of water are the key factors that affect the chemical and rheological properties of asphalt during moisture damage. Four kinds of water solutions, including distilled water, an acidic solution, alkaline solution and saline solution were used to investigate the effects of aqueous solute compositions on the chemical and rheological properties of asphalt. Thin-layer chromatography with flame ionization detection (TLC-FID), Fourier transform infrared (FTIR) spectroscopy and dynamic shear rheometer (DSR) were applied to investigate the components, chemistry and rheology characteristics of asphalt specimens before and after water solute exposure. The experimental results show that moisture damage of asphalt is not only associated with an oxidation process between asphalt with oxygen, but it is also highly dependent on some compounds of asphalt dissolving and being removed in the water solutions. In detail, after immersion in water solute, the fraction of saturates, aromatics and resins in asphalt binders decreased, while asphaltenes increased; an increase in the carbonyl and sulphoxide indices, and a decrease in the butadiene index were also found from the FTIR analyzer test. The rheological properties of asphalt are sensitive to water solute immersing. The addition of aqueous solutes causes more serious moisture damage on asphalt binders, with the pH11 solution presenting as the most destructive during water solute exposure.
Activity of water in aqueous systems; a frequently neglected property.

PubMed

Blandamer, Mike J; Engberts, Jan B F N; Gleeson, Peter T; Reis, Joao Carlos R

2005-05-01

In this critical review, the significance of the term 'activity' is examined in the context of the properties of aqueous solutions. The dependence of the activity of water(l) at ambient pressure and 298.15 K on solute molality is examined for aqueous solutions containing neutral solutes, mixtures of neutral solutes and salts. Addition of a solute to water(l) always lowers its thermodynamic activity. For some solutes the stabilisation of water(l) is less than and for others more than in the case where the thermodynamic properties of the aqueous solution are ideal. In one approach this pattern is accounted for in terms of hydrate formation. Alternatively the pattern is analysed in terms of the dependence of practical osmotic coefficients on the composition of the aqueous solution and then in terms of solute-solute interactions. For salt solutions the dependence of the activity of water on salt molalities is compared with that predicted by the Debye-Hückel limiting law. The analysis is extended to consideration of the activities of water in binary aqueous mixtures. The dependence on mole fraction composition of the activity of water in binary aqueous mixtures is examined. Different experimental methods for determining the activity of water in aqueous solutions are critically reviewed. The role of water activity is noted in a biochemical context, with reference to the quality, stability and safety of food and finally with regard to health science.
Anisotropic membranes for gas separation

DOEpatents

Gollan, Arye Z.

1987-01-01

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7.degree.-25.degree. C. and then air dried at ambient temperature, typically 10.degree.-30.degree. C.
An efficient flexible-order model for 3D nonlinear water waves

NASA Astrophysics Data System (ADS)

Engsig-Karup, A. P.; Bingham, H. B.; Lindberg, O.

2009-04-01

The flexible-order, finite difference based fully nonlinear potential flow model described in [H.B. Bingham, H. Zhang, On the accuracy of finite difference solutions for nonlinear water waves, J. Eng. Math. 58 (2007) 211-228] is extended to three dimensions (3D). In order to obtain an optimal scaling of the solution effort multigrid is employed to precondition a GMRES iterative solution of the discretized Laplace problem. A robust multigrid method based on Gauss-Seidel smoothing is found to require special treatment of the boundary conditions along solid boundaries, and in particular on the sea bottom. A new discretization scheme using one layer of grid points outside the fluid domain is presented and shown to provide convergent solutions over the full physical and discrete parameter space of interest. Linear analysis of the fundamental properties of the scheme with respect to accuracy, robustness and energy conservation are presented together with demonstrations of grid independent iteration count and optimal scaling of the solution effort. Calculations are made for 3D nonlinear wave problems for steep nonlinear waves and a shoaling problem which show good agreement with experimental measurements and other calculations from the literature.

Water flow in carbon-based nanoporous membranes impacted by interactions between hydrated ions and aromatic rings.

PubMed

Liu, Jian; Shi, Guosheng; Fang, Haiping

2017-02-24

Carbon-based nanoporous membranes, such as carbon nanotubes (CNTs), graphene/graphene oxide and graphyne, have shown great potential in water desalination and purification, gas and ion separation, biosensors, and lithium-based batteries, etc. A deep understanding of the interaction between hydrated ions in an aqueous solution and the graphitic surface in systems composed of water, ions and a graphitic surface is essential for applications with carbon-based nanoporous membrane platforms. In this review, we describe the recent progress of the interaction between hydrated ions and aromatic ring structures on the carbon-based surface and its applications in the water flow in a carbon nanotube. We expect that these works can be extended to the understanding of water flow in other nanoporous membranes, such as nanoporous graphene, graphyne and stacked sheets of graphene oxide.
Structural characterization of astaxanthin aggregates as revealed by analysis and simulation of optical spectra

NASA Astrophysics Data System (ADS)

Lu, Liping; Hu, Taoping; Xu, Zhigang

2017-10-01

Carotenoids can self-assemble in hydrated polar solvents to form J- or H-type aggregates, inducing dramatic changes in photophysical properties. Here, we measured absorption and emission spectra of astaxanthin in ethanol-water solution using ultraviolet-visible and fluorescence spectrometers. Two types of aggregates were distinguished in mixed solution at different water contents by absorption spectra. After addition of water, all probed samples immediately formed H-aggregates with maximum blue shift of 31 nm. In addition, J-aggregate was formed in 1:3 ethanol-water solution measured after an hour. Based on Frenkel exciton model, we calculated linear absorption and emission spectra of these aggregates to describe aggregate structures in solution. For astaxanthin, experimental results agreed well with the fitted spectra of H-aggregate models, which consisted of tightly packed stacks of individual molecules, including hexamers, trimers, and dimers. Transition moment of single astaxanthin in ethanol was obtained by Gaussian 09 program package to estimate the distance between molecules in aggregates. Intermolecular distance of astaxanthin aggregates ranges from 0.45 nm to 0.9 nm. Fluorescence analysis showed that between subbands, strong exciton coupling induced rapid relaxation of H-aggregates. This coupling generated larger Stokes shift than monomers and J-aggregates.
Osmosis and solute-solvent drag: fluid transport and fluid exchange in animals and plants.

PubMed

Hammel, H T; Schlegel, Whitney M

2005-01-01

In 1903, George Hulett explained how solute alters water in an aqueous solution to lower the vapor pressure of its water. Hulett also explained how the same altered water causes osmosis and osmotic pressure when the solution is separated from liquid water by a membrane permeable to the water only. Hulett recognized that the solute molecules diffuse toward all boundaries of the solution containing the solute. Solute diffusion is stopped at all boundaries, at an open-unopposed surface of the solution, at a semipermeable membrane, at a container wall, or at the boundary of a solid or gaseous inclusion surrounded by solution but not dissolved in it. At each boundary of the solution, the solute molecules are reflected, they change momentum, and the change of momentum of all reflected molecules is a pressure, a solute pressure (i.e., a force on a unit area of reflecting boundary). When a boundary of the solution is open and unopposed, the solute pressure alters the internal tension in the force bonding the water in its liquid phase, namely, the hydrogen bond. All altered properties of the water in the solution are explained by the altered internal tension of the water in the solution. We acclaim Hulett's explanation of osmosis, osmotic pressure, and lowering of the vapor pressure of water in an aqueous solution. His explanation is self-evident. It is the necessary, sufficient, and inescapable explanation of all altered properties of the water in the solution relative to the same property of pure liquid water at the same externally applied pressure and the same temperature. We extend Hulett's explanation of osmosis to include the osmotic effects of solute diffusing through solvent and dragging on the solvent through which it diffuses. Therein lies the explanations of (1) the extravasation from and return of interstitial fluid to capillaries, (2) the return of luminal fluid in the proximal and distal convoluted tubules of a kidney nephron to their peritubular capillaries, (3) the return of interstitial fluid to the vasa recta, (4) return of aqueous humor to the episcleral veins, and (5) flow of phloem from source to sink in higher plants and many more examples of fluid transport and fluid exchange in animal and plant physiology. When a membrane is permeable to water only and when it separates differing aqueous solutions, the flow of water is from the solution with the lower osmotic pressure to the solution with the higher osmotic pressure.
Reuse of process water in a waste-to-energy plant: An Italian case of study.

PubMed

Gardoni, Davide; Catenacci, Arianna; Antonelli, Manuela

2015-09-01

The minimisation of water consumption in waste-to-energy (WtE) plants is an outstanding issue, especially in those regions where water supply is critical and withdrawals come from municipal waterworks. Among the various possible solutions, the most general, simple and effective one is the reuse of process water. This paper discusses the effectiveness of two different reuse options in an Italian WtE plant, starting from the analytical characterisation and the flow-rate measurement of fresh water and process water flows derived from each utility internal to the WtE plant (e.g. cooling, bottom ash quenching, flue gas wet scrubbing). This census allowed identifying the possible direct connections that optimise the reuse scheme, avoiding additional water treatments. The effluent of the physical-chemical wastewater treatment plant (WWTP), located in the WtE plant, was considered not adequate to be directly reused because of the possible deposition of mineral salts and clogging potential associated to residual suspended solids. Nevertheless, to obtain high reduction in water consumption, reverse osmosis should be installed to remove non-metallic ions (Cl(-), SO4(2-)) and residual organic and inorganic pollutants. Two efficient solutions were identified. The first, a simple reuse scheme based on a cascade configuration, allowed 45% reduction in water consumption (from 1.81 to 0.99m(3)tMSW(-1), MSW: Municipal Solid Waste) without specific water treatments. The second solution, a cascade configuration with a recycle based on a reverse osmosis process, allowed 74% reduction in water consumption (from 1.81 to 0.46m(3)tMSW(-1)). The results of the present work show that it is possible to reduce the water consumption, and in turn the wastewater production, reducing at the same time the operating cost of the WtE plant. Copyright © 2015 Elsevier Ltd. All rights reserved.
Innovative sponge-based moving bed-osmotic membrane bioreactor hybrid system using a new class of draw solution for municipal wastewater treatment.

PubMed

Nguyen, Nguyen Cong; Chen, Shiao-Shing; Nguyen, Hau Thi; Ray, Saikat Sinha; Ngo, Huu Hao; Guo, Wenshan; Lin, Po-Hsun

2016-03-15

For the first time, an innovative concept of combining sponge-based moving bed (SMB) and an osmotic membrane bioreactor (OsMBR), known as the SMB-OsMBR hybrid system, were investigated using Triton X-114 surfactant coupled with MgCl2 salt as the draw solution. Compared to traditional activated sludge OsMBR, the SMB-OsMBR system was able to remove more nutrients due to the thick-biofilm layer on sponge carriers. Subsequently less membrane fouling was observed during the wastewater treatment process. A water flux of 11.38 L/(m(2) h) and a negligible reverse salt flux were documented when deionized water served as the feed solution and a mixture of 1.5 M MgCl2 and 1.5 mM Triton X-114 was used as the draw solution. The SMB-OsMBR hybrid system indicated that a stable water flux of 10.5 L/(m(2) h) and low salt accumulation were achieved in a 90-day operation. Moreover, the nutrient removal efficiency of the proposed system was close to 100%, confirming the effectiveness of simultaneous nitrification and denitrification in the biofilm layer on sponge carriers. The overall performance of the SMB-OsMBR hybrid system using MgCl2 coupled with Triton X-114 as the draw solution demonstrates its potential application in wastewater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.
Single water entropy: hydrophobic crossover and application to drug binding.

PubMed

Sasikala, Wilbee D; Mukherjee, Arnab

2014-09-11

Entropy of water plays an important role in both chemical and biological processes e.g. hydrophobic effect, molecular recognition etc. Here we use a new approach to calculate translational and rotational entropy of the individual water molecules around different hydrophobic and charged solutes. We show that for small hydrophobic solutes, the translational and rotational entropies of each water molecule increase as a function of its distance from the solute reaching finally to a constant bulk value. As the size of the solute increases (0.746 nm), the behavior of the translational entropy is opposite; water molecules closest to the solute have higher entropy that reduces with distance from the solute. This indicates that there is a crossover in translational entropy of water molecules around hydrophobic solutes from negative to positive values as the size of the solute is increased. Rotational entropy of water molecules around hydrophobic solutes for all sizes increases with distance from the solute, indicating the absence of crossover in rotational entropy. This makes the crossover in total entropy (translation + rotation) of water molecule happen at much larger size (>1.5 nm) for hydrophobic solutes. Translational entropy of single water molecule scales logarithmically (Str(QH) = C + kB ln V), with the volume V obtained from the ellipsoid of inertia. We further discuss the origin of higher entropy of water around water and show the possibility of recovering the entropy loss of some hypothetical solutes. The results obtained are helpful to understand water entropy behavior around various hydrophobic and charged environments within biomolecules. Finally, we show how our approach can be used to calculate the entropy of the individual water molecules in a protein cavity that may be replaced during ligand binding.
Proton transfer from water to ketyl radical anion: Assessment of critical size of hydrated cluster and free energy barrier in solution from first principles simulations

NASA Astrophysics Data System (ADS)

Biswas, Sohag; Dasgupta, Teesta; Mallik, Bhabani S.

2016-09-01

We present the reactivity of an organic intermediate by studying the proton transfer process from water to ketyl radical anion using gas phase electronic structure calculations and the metadynamics method based first principles molecular dynamics (FPMD) simulations. Our results indicate that during the micro solvation of anion by water molecules systematically, the presence of minimum three water molecules in the gas phase cluster is sufficient to observe the proton transfer event. The analysis of trajectories obtained from initial FPMD simulation of an aqueous solution of the anion does not show any evident of complete transfer of the proton from water. The cooperativity of water molecules and the relatively weak anion-water interaction in liquid state prohibit the full release of the proton. Using biasing potential through first principles metadynamics simulations, we report the observation of proton transfer reaction from water to ketyl radical anion with a barrier height of 16.0 kJ/mol.
Integrated solutions for urban runoff pollution control in Brazilian metropolitan regions.

PubMed

Morihama, A C D; Amaro, C; Tominaga, E N S; Yazaki, L F O L; Pereira, M C S; Porto, M F A; Mukai, P; Lucci, R M

2012-01-01

One of the most important causes for poor water quality in urban rivers in Brazil is the low collection efficiency of the sewer system due to unforeseen interconnections with the stormwater drainage system. Since the beginning of the 20th century, Brazilian cities have adopted separate systems for sanitary sewers and stormwater runoff. Gradually these two systems became interconnected. A major challenge faced today by water managers in Brazil is to find efficient and low cost solutions to deal with this mixed system. The current situation poses an important threat to the improvement of the water quality in urban rivers and lakes. This article presents an evaluation of the water quality parameters and the diffuse pollution loads during rain events in the Pinheiros River, a tributary of the Tietê River in São Paulo. It also presents different types of integrated solutions for reducing the pollution impact of combined systems, based on the European experience in urban water management. An evaluation of their performance and a comparison with the separate system used in most Brazilian cities is also presented. The study is based on an extensive water quality monitoring program that was developed for a special investigation in the Pinheiros River and lasted 2.5 years. Samples were collected on a daily basis and water quality variables were analyzed on a daily, weekly or monthly basis. Two hundred water quality variables were monitored at 53 sampling points. During rain events, additional monitoring was carried out using an automated sampler. Pinheiros River is one of the most important rivers in the São Paulo Metropolitan Region and it is also a heavily polluted one.
Risk-based decision making to manage water quality failures caused by combined sewer overflows

NASA Astrophysics Data System (ADS)

Sriwastava, A. K.; Torres-Matallana, J. A.; Tait, S.; Schellart, A.

2017-12-01

Regulatory authorities set certain environmental permit for water utilities such that the combined sewer overflows (CSO) managed by these companies conform to the regulations. These utility companies face the risk of paying penalty or negative publicity in case they breach the environmental permit. These risks can be addressed by designing appropriate solutions such as investing in additional infrastructure which improve the system capacity and reduce the impact of CSO spills. The performance of these solutions is often estimated using urban drainage models. Hence, any uncertainty in these models can have a significant effect on the decision making process. This study outlines a risk-based decision making approach to address water quality failure caused by CSO spills. A calibrated lumped urban drainage model is used to simulate CSO spill quality in Haute-Sûre catchment in Luxembourg. Uncertainty in rainfall and model parameters is propagated through Monte Carlo simulations to quantify uncertainty in the concentration of ammonia in the CSO spill. A combination of decision alternatives such as the construction of a storage tank at the CSO and the reduction in the flow contribution of catchment surfaces are selected as planning measures to avoid the water quality failure. Failure is defined as exceedance of a concentration-duration based threshold based on Austrian emission standards for ammonia (De Toffol, 2006) with a certain frequency. For each decision alternative, uncertainty quantification results into a probability distribution of the number of annual CSO spill events which exceed the threshold. For each alternative, a buffered failure probability as defined in Rockafellar & Royset (2010), is estimated. Buffered failure probability (pbf) is a conservative estimate of failure probability (pf), however, unlike failure probability, it includes information about the upper tail of the distribution. A pareto-optimal set of solutions is obtained by performing mean- pbf optimization. The effectiveness of using buffered failure probability compared to the failure probability is tested by comparing the solutions obtained by using mean-pbf and mean-pf optimizations.
A jazz-based approach for optimal setting of pressure reducing valves in water distribution networks

NASA Astrophysics Data System (ADS)

De Paola, Francesco; Galdiero, Enzo; Giugni, Maurizio

2016-05-01

This study presents a model for valve setting in water distribution networks (WDNs), with the aim of reducing the level of leakage. The approach is based on the harmony search (HS) optimization algorithm. The HS mimics a jazz improvisation process able to find the best solutions, in this case corresponding to valve settings in a WDN. The model also interfaces with the improved version of a popular hydraulic simulator, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the solutions. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to two case studies, and the obtained results in terms of pressure reductions are comparable with those of competitive metaheuristic algorithms (e.g. genetic algorithms). The results demonstrate the suitability of the HS algorithm for water network management and optimization.
Effects of artificial sweeteners on body weight, food and drink intake.

PubMed

Polyák, Eva; Gombos, K; Hajnal, B; Bonyár-Müller, K; Szabó, Sz; Gubicskó-Kisbenedek, A; Marton, K; Ember, I

2010-12-01

Artificial sweeteners are widely used all over the world. They may assist in weight management, prevention of dental caries, control of blood glucose of diabetics, and also can be used to replace sugar in foods. In the animal experimentation mice were given oral doses of water solutions of table top artificial sweeteners (saccharin, cyclamate based, acesulfame-K based, and aspartame) the amount of maximum Acceptable Daily Intake (ADI) ad libitum. The controls received only tap water with the same drinking conditions as the treated groups. The mice were fed chow ad libitum.We measured food intake and body weight once a week, water and solutions of artificial sweeteners intake twice a week. The data were analysed by statistical methods (T-probe, regression analysis).Consumption of sweeteners resulted in significantly increased body weight; however, the food intake did not change.These results question the effect of non-caloric artificial sweeteners on weight-maintenance or body weight decrease.
Method and apparatus for hydrogen production from water

NASA Technical Reports Server (NTRS)

Muradov, Nazim Z. (Inventor)

2012-01-01

A method, apparatuses and chemical compositions are provided for producing high purity hydrogen from water. Metals or alloys capable of reacting with water and producing hydrogen in aqueous solutions at ambient conditions are reacted with one or more inorganic hydrides capable of releasing hydrogen in aqueous solutions at ambient conditions, one or more transition metal compounds are used to catalyze the reaction and, optionally, one or more alkali metal-based compounds. The metal or alloy is preferably aluminum. The inorganic hydride is from a family of complex inorganic hydrides; most preferably, NaBH.sub.4. The transition metal catalyst is from the groups VIII and IB; preferably, Cu and Fe. The alkali metal-based compounds are preferably NaOH, KOH, and the like. Hydrogen generated has a purity of at least 99.99 vol. % (dry basis), and is used without further purification in all types of fuel cells, including the polymer electrolyte membrane (PEM) fuel cell.
Structure and dynamics of water in mixed solutions including laponite and PEO

NASA Astrophysics Data System (ADS)

Morikubo, Satoshi; Sekine, Yurina; Ikeda-Fukazawa, Tomoko

2011-01-01

To investigate the structure and dynamics of water in mixed solutions including laponite clay particles and poly(ethylene oxide) (PEO), we measured the Raman spectra of the mixed solutions in the temperature range 283-313 K. The results show that the vibrational energies of the O-H stretching modes in the mixed solutions depend on the water content and temperature. The energy shifts of the O-H stretching modes are attributed to changes in the water structure. By applying a structural model of bulk water to the spectra in the O-H stretching region, the local structures of water in the solutions were analyzed. The result shows that the formation probability of hydrogen bonds in the solutions decreases as the water content decreases. Laponite and PEO have effects to disrupt the network structure of hydrogen bonds between water molecules. Further, it was found that laponite and PEO cause increase in the strength of hydrogen bonds of surrounding water,although the strength of the hydrogen bonds increases with the order water-laponite < water-water < water-PEO. It is concluded that water in laponite-PEO mixed solutions has a less-networked structure with strong hydrogen bonds compared with bulk water.
Solitary wave solutions and their interactions for fully nonlinear water waves with surface tension in the generalized Serre equations

NASA Astrophysics Data System (ADS)

Dutykh, Denys; Hoefer, Mark; Mitsotakis, Dimitrios

2018-04-01

Some effects of surface tension on fully nonlinear, long, surface water waves are studied by numerical means. The differences between various solitary waves and their interactions in subcritical and supercritical surface tension regimes are presented. Analytical expressions for new peaked traveling wave solutions are presented in the dispersionless case of critical surface tension. Numerical experiments are performed using a high-accurate finite element method based on smooth cubic splines and the four-stage, classical, explicit Runge-Kutta method of order 4.
Cloud point extraction thermospray flame quartz furnace atomic absorption spectrometry for determination of ultratrace cadmium in water and urine

NASA Astrophysics Data System (ADS)

Wu, Peng; Zhang, Yunchang; Lv, Yi; Hou, Xiandeng

2006-12-01

A simple, low cost and highly sensitive method based on cloud point extraction (CPE) for separation/preconcentration and thermospray flame quartz furnace atomic absorption spectrometry was proposed for the determination of ultratrace cadmium in water and urine samples. The analytical procedure involved the formation of analyte-entrapped surfactant micelles by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution and a Triton X-114 solution. When the temperature of the system was higher than the cloud point of Triton X-114, the complex of cadmium-PDC entered the surfactant-rich phase and thus separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, the limit of detection was 0.04 μg/L for cadmium with a sample volume of 10 mL. The analytical results of cadmium in water and urine samples agreed well with those by ICP-MS.
Nonlinear storage models of unconfined flow through a shallow aquifer on an inclined base and their quasi-steady flow application

NASA Astrophysics Data System (ADS)

Varvaris, Ioannis; Gravanis, Elias; Koussis, Antonis; Akylas, Evangelos

2013-04-01

Hillslope processes involving flow through an inclined shallow aquifer range from subsurface stormflow to stream base flow (drought flow, or groundwater recession flow). In the case of recharge, the infiltrating water moves vertically as unsaturated flow until it reaches the saturated groundwater, where the flow is approximately parallel to the base of the aquifer. Boussinesq used the Dupuit-Forchheimer (D-F) hydraulic theory to formulate unconfined groundwater flow through a soil layer resting on an impervious inclined bed, deriving a nonlinear equation for the flow rate that consists of a linear gravity-driven component and a quadratic pressure-gradient component. Inserting that flow rate equation into the differential storage balance equation (volume conservation) Boussinesq obtained a nonlinear second-order partial differential equation for the depth. So far however, only few special solutions have been advanced for that governing equation. The nonlinearity of the equation of Boussinesq is the major obstacle to deriving a general analytical solution for the depth profile of unconfined flow on a sloping base with recharge (from which the discharges could be then determined). Henderson and Wooding (1964) were able to obtain an exact analytical solution for steady unconfined flow on a sloping base, with recharge, and their work deserves special note in the realm of solutions of the nonlinear equation of Boussinesq. However, the absence of a general solution for the transient case, which is of practical interest to hydrologists, has been the motivation for developing approximate solutions of the non-linear equation of Boussinesq. In this work, we derive the aquifer storage function by integrating analytically over the aquifer base the depth profiles resulting from the complete nonlinear Boussinesq equation for steady flow. This storage function consists of a linear and a nonlinear outflow-dependent term. Then, we use this physics-based storage function in the transient storage balance over the hillslope, obtaining analytical solutions of the outflow and the storage, for recharge and drainage, via a quasi-steady flow calculation. The hydraulically derived storage model is thus embedded in a quasi-steady approximation of transient unconfined flow in sloping aquifers. We generalise this hydrologic model of groundwater flow by modifying the storage function to be the weighted sum of the linear and the nonlinear storage terms, determining the weighting factor objectively from a known integral quantity of the flow (either an initial volume of water stored in the aquifer or a drained water volume). We demonstrate the validity of this model through comparisons with experimental data and simulation results.
Concept and Connotation of Water Resources Carrying Capacity in Water Ecological Civilization Construction

NASA Astrophysics Data System (ADS)

Chao, Zhilong; Song, Xiaoyu; Feng, Xianghua

2018-01-01

Water ecological civilization construction is based on the water resources carrying capacity, guided by the sustainable development concept, adhered to the human-water harmony thoughts. This paper has comprehensive analyzed the concept and characteristics of the carrying capacity of water resources in the water ecological civilization construction, and discussed the research methods and evaluation index system of water carrying capacity in the water ecological civilization construction, finally pointed out that the problems and solutions of water carrying capacity in the water ecological civilization construction and put forward the future research prospect.
Application of forward osmosis technology in crude glycerol fermentation biorefinery-potential and challenges.

PubMed

Kalafatakis, S; Braekevelt, S; Lymperatou, A; Zarebska, A; Hélix-Nielsen, C; Lange, L; Skiadas, I V; Gavala, H N

2018-04-24

Forward osmosis (FO) is a low energy-intensive process since the driving force for water transport is the osmotic pressure difference, Δπ, between the feed and draw solutions, separated by the FO membrane, where π draw > π feed . The potential of FO in wastewater treatment and desalination have been extensively studied; however, regeneration of the draw solution (thereby generating clean water) requires application of an energy-intensive process step like reverse osmosis (RO). In this study, the potential of applying FO for direct water recirculation from diluted fermentation effluent to concentrated feedstock, without the need for an energy-intensive regeneration step (e.g. RO), has been investigated. Butanol production during crude glycerol fermentation by Clostridium pasteurianum, has been selected as a model process and the effect of cross-flow velocity and the dilution of draw solution on the water flux during short-term experiments (200 min), were investigated. Statistical analysis revealed that the dilution of the draw solution is the most influential factor for the water flux. Subsequent modelling of an integrated FO-fermentation process, showed that water recoveries could lead to substantial financial benefits, although the integrated FO-fermentation process demonstrated lower water flux than expected. FTIR analyses of the membrane surface implied that the decrease in water flux was due to the presence of proteins, polysaccharides and other extracellular polymeric substances on the membrane active layer, indicating the presence of a fouling layer. Based on these findings, possible fouling alleviation strategies and future research directions are discussed and proposed.
Variations in surface water-ground water interactions along a headwater mountain stream : comparisons between transient storage and water balance analyses

USGS Publications Warehouse

Ward, Adam S.; Payn, Robert A.; Gooseff, Michael N.; McGlynn, Brian L.; Bencala, Kenneth E.; Kelleher, Christa A.; Wondzell, Steven M.; Wagener, Thorsten

2013-01-01

The accumulation of discharge along a stream valley is frequently assumed to be the primary control on solute transport processes. Relationships of both increasing and decreasing transient storage, and decreased gross losses of stream water have been reported with increasing discharge; however, we have yet to validate these relationships with extensive ﬁeld study. We conducted transient storage and mass recovery analyses of artiﬁcial tracer studies completed for 28 contiguous 100 m reaches along a stream valley, repeated under four base-ﬂow conditions. We calculated net and gross gains and losses, temporal moments of tracer breakthrough curves, and best ﬁt transient storage model parameters (with uncertainty estimates) for 106 individual tracer injections. Results supported predictions that gross loss of channel water would decrease with increased discharge. However, results showed no clear relationship between discharge and transient storage, and further analysis of solute tracer methods demonstrated that the lack of this relation may be explained by uncertainty and equiﬁnality in the transient storage model framework. Furthermore, comparison of water balance and transient storage approaches reveals complications in clear interpretation of either method due to changes in advective transport time, which sets a the temporal boundary separating transient storage and channel water balance. We have little ability to parse this limitation of solute tracer methods from the physical processes we seek to study. We suggest the combined analysis of both transient storage and channel water balance more completely characterizes transport of solutes in stream networks than can be inferred from either method alone.
Modularized and water-cooled photo-catalyst cleaning devices for aquaponics based on ultraviolet light-emitting diodes

NASA Astrophysics Data System (ADS)

Yang, Henglong; Lung, Louis; Wei, Yu-Chien; Huang, Yi-Bo; Chen, Zi-Yu; Chou, Yu-Yang; Lin, Anne-Chin

2017-08-01

The feasibility of applying ultraviolet light-emitting diodes (UV-LED's) as triggering sources of photo-catalyst based on titanium dioxide (TiO2) nano-coating specifically for water-cleaning process in an aquaponics system was designed and proposed. The aquaponics system is a modern farming system to integrate aquaculture and hydroponics into a single system to establish an environmental-friendly and lower-cost method for farming fish and vegetable all together in urban area. Water treatment in an aquaponics system is crucial to avoid mutual contamination. we proposed a modularized watercleaning device composed of all commercially available components and parts to eliminate organic contaminants by using UV-LED's for TiO2 photo-catalyst reaction. This water-cleaning module consisted of two coaxial hollowed cylindrical pipes can be submerged completely in water for water treatment and cooling UV-LED's. The temperature of the UV-LED after proper thermal management can be reduced about 16% to maintain the optimal operation condition. Our preliminary experimental result by using Methylene Blue solution to simulate organic contaminants indicated that TiO2 photo-catalyst triggered by UV-LED's can effectively decompose organic compound and decolor Methylene Blue solution.

Ground-water models for water resource planning

USGS Publications Warehouse

Moore, J.E.

1983-01-01

In the past decade hydrogeologists have emphasized the development of computer-based mathematical models to aid in the understanding of flow, the transport of solutes, transport of heat, and deformation in the ground-water system. These models have been used to provide information and predictions for water managers. Too frequently, ground-water was neglected in water resource planning because managers believed that it could not be adequately evaluated in terms of availability, quality, and effect of development on surface-water supplies. Now, however, with newly developed digital ground-water models, effects of development can be predicted. Such models have been used to predict hydrologic and quality changes under different stresses. These models have grown in complexity over the last ten years from simple one-layer models to three-dimensional simulations of ground-water flow, which may include solute transport, heat transport, effects of land subsidence, and encroachment of saltwater. Case histories illustrate how predictive ground-water models have provided the information needed for the sound planning and management of water resources in the USA. ?? 1983 D. Reidel Publishing Company.
Immediate impact on the rim zone of cement based materials due to chemical attack

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

Schwotzer, M., E-mail: matthias.schwotzer@kit.edu; Scherer, T.; Gerdes, A.

2015-01-15

Cement based materials are in their widespread application fields exposed to various aqueous environments. This can lead to serious chemical changes affecting the durability of the materials. In particular in the context of service life prediction a detailed knowledge of the reaction mechanisms is a necessary base for the evaluation of the aggressivity of an aqueous medium and this is deduced commonly from long term investigations. However, these processes start immediately at the material/water-interface, when a cementitious system comes into contact with an aqueous solution, altering here the chemical composition and microstructure. This rim zone represents the first hurdle thatmore » has to be overcome by an attacking aqueous solution. Therefore, the properties of the surface near area should be closely associated with the further course of deterioration processes by reactive transport. In this context short term exposure experiments with hardened cement paste over 4 and 48 h have been carried out with demineralized water, hard tap water and different sulfate solutions. In order to investigate immediate changes in the near-surface region, depth profile cuts have been performed on the cement paste samples by means of focused ion beam preparation techniques. A scanning beam of Gallium ions is applied to cut a sharp edge in the cement paste surface, providing insights into the composition and microstructure of the upper ten to hundred microns. Electron microscopic investigations on such a section of the rim zone, together with surface sensitive X-ray diffraction accompanied by a detailed characterization of the bulk composition confirm that the properties of the material/water interface are of relevance for the durability of cement based systems in contact with aqueous solutions. In this manner, focused ion beam investigations constitute auspicious tools to contribute to a more sophisticated understanding of the reaction mechanisms. - Highlights: • The chemical stability is related to the properties of material/water interface. • Properties of the rim zone readjust quickly, triggered by hydrochemical conditions. • Durability research can be improved by combining FIB techniques and common analytics.« less
A Latent Cue Preference Based on Sodium Depletion in Rats

ERIC Educational Resources Information Center

Stouffer, Eric M.; White, Norman M.

2005-01-01

Three experiments show latent (or incidental) learning of salt-cue relationships using a conditioned cue-preference paradigm. Rats drank a salt solution while confined in one compartment and water in an adjacent, distinct compartment on alternate days. When given access to the two compartments with no solutions present, sodium-deprived rats…
Aerosol hygroscopic growth parameterization based on a solute specific coefficient

NASA Astrophysics Data System (ADS)

Metzger, S.; Steil, B.; Xu, L.; Penner, J. E.; Lelieveld, J.

2011-09-01

Water is a main component of atmospheric aerosols and its amount depends on the particle chemical composition. We introduce a new parameterization for the aerosol hygroscopic growth factor (HGF), based on an empirical relation between water activity (aw) and solute molality (μs) through a single solute specific coefficient νi. Three main advantages are: (1) wide applicability, (2) simplicity and (3) analytical nature. (1) Our approach considers the Kelvin effect and covers ideal solutions at large relative humidity (RH), including CCN activation, as well as concentrated solutions with high ionic strength at low RH such as the relative humidity of deliquescence (RHD). (2) A single νi coefficient suffices to parameterize the HGF for a wide range of particle sizes, from nanometer nucleation mode to micrometer coarse mode particles. (3) In contrast to previous methods, our analytical aw parameterization depends not only on a linear correction factor for the solute molality, instead νi also appears in the exponent in form x · ax. According to our findings, νi can be assumed constant for the entire aw range (0-1). Thus, the νi based method is computationally efficient. In this work we focus on single solute solutions, where νi is pre-determined with the bisection method from our analytical equations using RHD measurements and the saturation molality μssat. The computed aerosol HGF and supersaturation (Köhler-theory) compare well with the results of the thermodynamic reference model E-AIM for the key compounds NaCl and (NH4)2SO4 relevant for CCN modeling and calibration studies. The equations introduced here provide the basis of our revised gas-liquid-solid partitioning model, i.e. version 4 of the EQuilibrium Simplified Aerosol Model (EQSAM4), described in a companion paper.
Solution influence on biomolecular equilibria - Nucleic acid base associations

NASA Technical Reports Server (NTRS)

Pohorille, A.; Pratt, L. R.; Burt, S. K.; Macelroy, R. D.

1984-01-01

Various attempts to construct an understanding of the influence of solution environment on biomolecular equilibria at the molecular level using computer simulation are discussed. First, the application of the formal statistical thermodynamic program for investigating biomolecular equilibria in solution is presented, addressing modeling and conceptual simplications such as perturbative methods, long-range interaction approximations, surface thermodynamics, and hydration shell. Then, Monte Carlo calculations on the associations of nucleic acid bases in both polar and nonpolar solvents such as water and carbon tetrachloride are carried out. The solvent contribution to the enthalpy of base association is positive (destabilizing) in both polar and nonpolar solvents while negative enthalpies for stacked complexes are obtained only when the solute-solute in vacuo energy is added to the total energy. The release upon association of solvent molecules from the first hydration layer around a solute to the bulk is accompanied by an increase in solute-solvent energy and decrease in solvent-solvent energy. The techniques presented are expectd to displace less molecular and more heuristic modeling of biomolecular equilibria in solution.
Superlubricity of a Mixed Aqueous Solution

NASA Astrophysics Data System (ADS)

Ma, Zhi-Zuo; Zhang, Chen-Hui; Luo, Jian-Bin; Lu, Xin-Chun; Wen, Shi-Zhu

2011-05-01

A super-low friction coefficient of 0.0028 is measured under a pressure of 300 MPa when the friction pair (the silicon nitride ball sliding on the silicate glass) is lubricated by the mixed aqueous solution of glycerol and boric acid. The morphorlogies of the hydroxylated glass plate are observed by an atomic force microscope (AFM) in deionized water, glycerol, boric acid and their mixed aqueous solution. Bonding peaks of the retained liquids adhered on the surface of the sliding track are detected by an infrared spectrum apparatus and a Raman spectrum apparatus. The mechanism of the superlubricity of the glycerol and boric acid mixed aqueous solution is discussed. It is deduced that the formation of the lubricant film has enough strength to support higher loads, the hydration effect offering the super lower shear resistance. Key words: superlubricity, water based lubricant, ultra-low friction
Analytical solutions of travel time to a pumping well with variable evapotranspiration.

PubMed

Chen, Tian-Fei; Wang, Xu-Sheng; Wan, Li; Li, Hailong

2014-01-01

Analytical solutions of groundwater travel time to a pumping well in an unconfined aquifer have been developed in previous studies, however, the change in evapotranspiration was not considered. Here, we develop a mathematical model of unconfined flow toward a discharge well with redistribution of groundwater evapotranspiration for travel time analysis. Dependency of groundwater evapotranspiration on the depth to water table is described using a linear formula with an extinction depth. Analytical solutions of groundwater level and travel time are obtained. For a typical hypothetical example, these solutions perfectly agree with the numerical simulation results based on MODFLOW and MODPATH. As indicated in a dimensionless framework, a lumped parameter which is proportional to the pumping rate controls the distributions of groundwater evapotranspiration rate and the travel time along the radial direction. © 2013, National Ground Water Association.
Salting-out effect in aqueous NaCl solutions: trends with size and polarity of solute molecules.

PubMed

Endo, Satoshi; Pfennigsdorff, Andrea; Goss, Kai-Uwe

2012-02-07

Salting-out in aqueous NaCl solutions is relevant for the environmental behavior of organic contaminants. In this study, Setschenow (or salting-out) coefficients (K(s) [M(-1)]) for 43 diverse neutral compounds in NaCl solutions were measured using a shared headspace passive dosing method and a negligible depletion solid phase microextraction technique. The results were used to calibrate and evaluate estimation models for K(s). The molar volume of the solute correlated only moderately with K(s) (R(2) = 0.49, SD = 0.052). The polyparameter linear free energy relationship (pp-LFER) model that uses five compound descriptors resulted in a more accurate fit to our data (R(2) = 0.83, SD = 0.031). The pp-LFER analysis revealed that Na(+) and Cl(-) in aqueous solutions increase the cavity formation energy cost and the polar interaction energies toward neutral organic solutes. Accordingly, the salting-out effect increases with the size and decreases with the polarity of the solute molecule. COSMO-RS, a quantum mechanics-based fully predictive model, generally overpredicted the experimental K(s), but the predicted values were moderately correlated with the experimental values (R(2) = 0.66, SD = 0.042). Literature data (n = 93) were predicted by the calibrated pp-LFER and COSMO-RS models with root mean squared errors of 0.047 and 0.050, respectively. This study offers prediction models to estimate K(s), allowing implementation of the salting-out effect in contaminant fate models, linkage of various partition coefficients (such as air-water, sediment-water, and extraction phase-water partition coefficients) measured for fresh water and seawater, and estimation of enhancement of extraction efficiency in analytical procedures.
Quantitative extraction and concentration of synthetic water-soluble acid dyes from aqueous media using a quinine-chloroform solution

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

Kobayashi, F.; Ozawa, N.; Hanai, J.

Twenty-one water-soluble acid dyes, including eleven azo, five triphenylmethane four xanthene, one naphthol derivatives, used at practical concentrations for food coloration, were quantitatively extracted from water and various carbonated beverages into a 0.1 M quinine-chloroform solution in the presence of 0.5 M boric acid by brief shaking. Quantitative extraction of these dyes was also accomplished by the 0.1 M quinine-chloroform solution made conveniently from chloroform, quinine hydrochloride, and sodium hydroxide added successively to water or beverages containing boric acid. Quinine acted as a countercation on the dyes having sulfonic and/or carboxylic acid group(s) to form chloroform-soluble ion-pair complexes. The diacidicmore » base alkaloid interacted with each acid group of mono-, di-, tri-, and tetrasulfonic acid dyes approximately in the ratio 0.8-0.9 to 1. The dyes in the chloroform solution were quantitatively concentrated into a small volume of sodium hydroxide solution also by brief shaking. The convenient quinine-chloroform method was applicable to the quantitative extraction of a mixture of 12 dyes from carbonated beverages, which are all currently used for food coloration. A high-pressure liquid chromatographic method is also presented for the systematic separation and determination of these 12 dyes following their concentration into the aqueous alkaline solution. The chromatogram was monitored by double-wavelength absorptiometry in the visible and ultraviolet ray regions.« less
Dope dyeing of lyocell fiber with NMMO-based carbon black dispersion.

PubMed

Zhang, Liping; Sun, Weize; Xu, Dan; Li, Min; Agbo, Christiana; Fu, Shaohai

2017-10-15

NMMO-based carbon black (CB) dispersion was prepared and its properties as well as its compatibility with lyocell spinning solution were further investigated. Modified lignosulfonate (SP) was verified to be the preeminent dispersant for the preparation of NMMO-based CB dispersion with mass ratio of SP to CB 20% and water to NMMO 13%. The compatibility of NMMO-based CB dispersion with lyocell spinning solution had close relation with dispersant structure and CB content. Mass ratio of CB to cellulose affects the mechanical properties, color strength and crystallinity of lyocell fiber. 0.5% CB increased the breaking strength and elongation of lyocell fiber, whiles breaking strength and elongation of the lyocell fiber were reduced slightly when 2.0% CB was used. The dope dyed fiber showed excellent rubbing and washing fastness as well as migration resistance to water, ethanol and acetone. Copyright © 2017 Elsevier Ltd. All rights reserved.
Nonideality in diffusion of ionic and hydrophobic solutes and pair dynamics in water-acetone mixtures of varying composition.

PubMed

Gupta, Rini; Chandra, Amalendu

2007-07-14

We have performed a series of molecular dynamics simulations of water-acetone mixtures containing either an ionic solute or a neutral hydrophobic solute to study the extent of nonideality in the dynamics of these solutes with variation of composition of the mixtures. The diffusion coefficients of the charged solutes, both cationic and anionic, are found to change nonmonotonically with the composition of the mixtures showing strong nonideality of their dynamics. Also, the extent of nonideality in the diffusion of these charged solutes is found to be similar to the nonideality that is observed for the diffusion and orientational relaxation of water and acetone molecules in these mixtures which show a somewhat similar changes in the solvation characteristics of charged and dipolar solutes with changes of composition of water-acetone mixtures. The diffusion of the hydrophobic solute, however, shows a monotonic increase with increase of acetone concentration showing its different solvation characteristics as compared to the charged and dipolar solutes. The links between the nonideality in diffusion and solvation structures are further confirmed through calculations of the relevant solute-solvent and solvent-solvent radial distribution functions for both ionic and hydrophobic solutes. We have also calculated various pair dynamical properties such as the relaxation of water-water and acetone-water hydrogen bonds and residence dynamics of water molecules in water and acetone hydration shells. The lifetimes of both water-water and acetone-water hydrogen bonds and also the residence times of water molecules are found to increase steadily with increase in acetone concentration. No maximum or minimum was found in the composition dependence of these pair dynamical quantities. The lifetimes of water-water hydrogen bonds are always found to be longer than that of acetone-water hydrogen bonds in these mixtures. The residence times of water molecules are also found to follow a similar trend.
An overview on exploration and environmental impact of unconventional gas sources and treatment options for produced water.

PubMed

Silva, Tânia L S; Morales-Torres, Sergio; Castro-Silva, Sérgio; Figueiredo, José L; Silva, Adrián M T

2017-09-15

Rising global energy demands associated to unbalanced allocation of water resources highlight the importance of water management solutions for the gas industry. Advanced drilling, completion and stimulation techniques for gas extraction, allow more economical access to unconventional gas reserves. This stimulated a shale gas revolution, besides tight gas and coalbed methane, also causing escalating water handling challenges in order to avoid a major impact on the environment. Hydraulic fracturing allied to horizontal drilling is gaining higher relevance in the exploration of unconventional gas reserves, but a large amount of wastewater (known as "produced water") is generated. Its variable chemical composition and flow rates, together with more severe regulations and public concern, have promoted the development of solutions for the treatment and reuse of such produced water. This work intends to provide an overview on the exploration and subsequent environmental implications of unconventional gas sources, as well as the technologies for treatment of produced water, describing the main results and drawbacks, together with some cost estimates. In particular, the growing volumes of produced water from shale gas plays are creating an interesting market opportunity for water technology and service providers. Membrane-based technologies (membrane distillation, forward osmosis, membrane bioreactors and pervaporation) and advanced oxidation processes (ozonation, Fenton, photocatalysis) are claimed to be adequate treatment solutions. Copyright © 2017 Elsevier Ltd. All rights reserved.
A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

PubMed

Kadhom, Mohammed; Yin, Jun; Deng, Baolin

2016-12-06

Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An m -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m²·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi)).
Electrospinning bioactive supramolecular polymers from water.

PubMed

Tayi, Alok S; Pashuck, E Thomas; Newcomb, Christina J; McClendon, Mark T; Stupp, Samuel I

2014-04-14

Electrospinning is a high-throughput, low-cost technique for manufacturing long fibers from solution. Conventionally, this technique is used with covalent polymers with large molecular weights. We report here the electrospinning of functional peptide-based supramolecular polymers from water at very low concentrations (<4 wt %). Molecules with low molecular weights (<1 kDa) could be electrospun because they self-assembled into one-dimensional supramolecular polymers upon solvation and the critical parameters of viscosity, solution conductivity, and surface tension were optimized for this technique. The supramolecular structure of the electrospun fibers could ensure that certain residues, like bioepitopes, are displayed on the surface even after processing. This system provides an opportunity to electrospin bioactive supramolecular materials from water for biomedical applications.
First-Principles pH Theory

NASA Astrophysics Data System (ADS)

Kim, Yong-Hyun; Zhang, S. B.

2006-03-01

Despite being one of the most important macroscopic measures and a long history even before the quantum mechanics, the concept of pH has rarely been mentioned in microscopic theories, nor being incorporated computationally into first-principles theory of aqueous solutions. Here, we formulate a theory for the pH dependence of solution formation energy by introducing the proton chemical potential as the microscopic counterpart of pH in atomistic solution models. Within the theory, the general acid-base chemistry can be cast in a simple pictorial representation. We adopt density-functional molecular dynamics to demonstrate the usefulness of the method by studying a number of solution systems including water, small solute molecules such as NH3 and HCOOH, and more complex amino acids with several functional groups. For pure water, we calculated the auto- ionization constant to be 13.2 with a 95 % accuracy. For other solutes, the calculated dissociation constants, i.e., the so- called pKa, are also in reasonable agreement with experiments. Our first-principles pH theory can be readily applied to broad solution chemistry problems such as redox reactions.
An ionic liquid-in-water microemulsion as a potential carrier for topical delivery of poorly water soluble drug: Development, ex-vivo and in-vivo evaluation.

PubMed

Goindi, Shishu; Kaur, Ramanpreet; Kaur, Randeep

2015-11-30

In this paper, we report an ionic liquid-in-water (IL/w) microemulsion (ME) formulation which is able to solubilize etodolac (ETO), a poorly water soluble drug for topical delivery using BMIMPF6 (1-butyl-3-methylimidazolium hexafluorophosphate) as IL, Tween 80 as surfactant and ethanol as co-surfactant. The prepared ME was characterized for physicochemical parameters, subjected to ex-vivo permeation studies as well as in-vivo pharmacodynamic evaluation. The ex-vivo drug permeation studies through rat skin was performed using Franz-diffusion cell and the IL/w based ME showed maximum mean cumulative percent permeation of 99.030±0.921% in comparison to oil-in-water (o/w) ME (61.548±1.875%) and oily solution (48.830±2.488%) of ETO. In-vivo anti-arthritic and anti-inflammatory activities of the prepared formulations were evaluated using different rodent models and the results revealed that ETO loaded IL/w based ME was found to be more effective in controlling inflammation than oily solution, o/w ME and marketed formulation of ETO. Histopathological studies also demonstrated that IL/w based ME caused no anatomical and pathological changes in the skin. Copyright © 2015 Elsevier B.V. All rights reserved.
The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions

PubMed Central

Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

2016-01-01

It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions. PMID:27225427
Temporal trends of bulk precipitation and stream water chemistry (1977-1997) in a small forested area, Krusne hory, northern Bohemia, Czech Republic

USGS Publications Warehouse

Peters, N.E.; Cerny, J.; Havel, M.; Krejci, R.

1999-01-01

The Krusne hory (Erzgebirge or Ore Mountains) has been heavily affected by high atmospheric pollutant deposition caused by fossil fuel combustion in an adjacent Tertiary coal basin. Long-term routine sampling of bulk precipitation (1977-1996) and stream water (1977-1998) in a forested area on the south-eastern slope of the mountains were used to evaluate trends and patterns in solute concentration and flux with respect to controlling processes. From 1977 to 1996, the annual volume-weighted Ca2+ and SO42- concentrations decreased in bulk precipitation. However, after 1989, when a pronounced and continuous decrease occurred in coal production, annual volume-weighted concentrations decreased for most solutes, except H+. The concentration decreases were marked, with 1996 levels at or below 50% of those in 1989. The lack of a trend in H+ is attributed to similar decreases in both acid anions and neutralizing base cations. Stream water concentrations of most solutes, i.e. H+, Ca2+, Mg2+, SO42- and NO3-, were highest at the onset of sampling in 1977, decreased markedly from 1977 to 1983 and decreased more gradually from 1983 to 1998. The spruce forest die-back and removal reduced dry deposition of these solutes by reducing the filtering action, which was provided by the forest canopy. A notable decrease in stream water Ca2+ concentrations occurred after 1995 and may be due to the depletion of Ca2+, which was provided by catchment liming in 1986, 1988 and 1989. Solute flux trends in bulk atmospheric deposition and stream water generally were not significant and the lack of trend is attributed to the large interannual variability in precipitation quantity and runoff, respectively. All solutes except Na+ varied seasonally. The average seasonal concentrations varied between the solutes, but for most solutes were highest in winter and spring and lowest in summer, correlating with the seasonal trend and runoff. For Ca2+, Mg2+ and SO42-, the concentration minimum occurs in September and the maximum occurs in February or March, correlating with the seasonal baseflow. These solutes are primarily controlled by the contribution of soil water and groundwater to stream flow. During snowmelt, the meltwater generally causes concentrations to decrease as soil water and groundwater are diluted. For NO3, average minimum concentrations occur in August at the end of the growing season concurrent with the lowest stream flow, and the maximum occurs in February and March with high stream flow during snowmelt. Seasonal stream water NO3- concentration variations are large compared with the long-term decrease.The Krusne hory (Erzgebirge or Ore Mountains) has been heavily affected by high atmospheric pollutant deposition caused by fossil fuel combustion in an adjacent Tertiary coal basin. Long-term routine sampling of bulk precipitation (1977-1996) and stream water (1977-1998) in a forested area on the south-eastern slope of the mountains were used to evaluate trends and patterns in solute concentration and flux with respect to controlling processes. From 1977 to 1996, the annual volume-weighted Ca2+ and SO42- concentrations decreased in bulk precipitation. However, after 1989, when a pronounced and continuous decrease occurred in coal production, annual volume-weighted concentrations decreased for most solutes, except H+. The concentration decreases were marked, with 1996 levels at or below 50% of those in 1989. The lack of a trend in H+ is attributed to similar decreases in both acid anions and neutralizing base cations. Stream water concentrations of most solutes, i.e. H+, Ca2+, Mg2+, SO42- and NO3-, were highest at the onset of sampling in 1977, decreased markedly from 1977 to 1983 and decreased more gradually from 1983 to 1998. The spruce forest die-back and removal reduced dry deposition of these solutes by reducing the filtering action, which was provided by the forest canopy. A notable decrease in stream water Ca2+ concentrations occurred after 1995 an
Assessing the impact of transitions from centralised to decentralised water solutions on existing infrastructures – Integrated city-scale analysis with VIBe

PubMed Central

Sitzenfrei, Robert; Möderl, Michael; Rauch, Wolfgang

2013-01-01

Traditional urban water management relies on central organised infrastructure, the most important being the drainage network and the water distribution network. To meet upcoming challenges such as climate change, the rapid growth and shrinking of cities and water scarcity, water infrastructure needs to be more flexible, adaptable and sustainable (e.g., sustainable urban drainage systems, SUDS; water sensitive urban design, WSUD; low impact development, LID; best management practice, BMP). The common feature of all solutions is the push from a central solution to a decentralised solution in urban water management. This approach opens up a variety of technical and socio-economic issues, but until now, a comprehensive assessment of the impact has not been made. This absence is most likely attributable to the lack of case studies, and the availability of adequate models is usually limited because of the time- and cost-intensive preparation phase. Thus, the results of the analysis are based on a few cases and can hardly be transferred to other boundary conditions. VIBe (Virtual Infrastructure Benchmarking) is a tool for the stochastic generation of urban water systems at the city scale for case study research. With the generated data sets, an integrated city-scale analysis can be performed. With this approach, we are able to draw conclusions regarding the technical effect of the transition from existing central to decentralised urban water systems. In addition, it is shown how virtual data sets can assist with the model building process. A simple model to predict the shear stress performance due to changes in dry weather flow production is developed and tested. PMID:24210508
Sustainable Drainage, Green Infrastructure or Natural Flood Management - which should you choose?

NASA Astrophysics Data System (ADS)

Wingfield, Thea; Potter, Karen; Jones, Gareth; Spees, Jack; Macdonald, Neil

2016-04-01

River catchments as management units are more effective than administrative boundaries to integrate and coordinate efforts of organisations that utilise and manage water, soil and habitat quality. The UK government announced a pilot integrated water management initiative called, 'The Catchment Based Approach', on World Water Day 2011. After successful trials the scheme was extended to all river catchments in England during the summer of 2013. This policy has been designed to improve the collaboration, partnership and coordination of organisations involved in water and land management through locally led partnership groups. The lead organisations are all charitable bodies with significantly varying levels of experience of stormwater management; a key component of integrated water management and of great concern to communities at risk. These partnerships have implemented a number of Nature Based Solutions, but these have been presented in different ways by the different groups. In the UK there are three terms commonly used to describe Nature Based Solutions for managing the drainage of stormwater: Sustainable Drainage (SuDS), Green Infrastructure (GI) and Natural Flood Management (NFM). The definitions of each refers to the replication of natural hydrological processes in order to slow the flow of water through the landscape. But, there has been some concerns as to which of these nature based terms should be applied and why they appear to be used interchangeably. This study demonstrates that, despite the definitions of these three terms being almost identical, in practice they are not the same and should not be used interchangeably. The terms were developed by different professional groups in response to their own objectives and histories. The hydrological processes used to manage storm-water may be the same and the suggested interventions may show a degree of convergence. Yet, they operate at different scales, both geographically and organisationally. The different professional disciplines have their own ideologies and work to distinct governing regulations which manage and perceive operational risk in varying ways. All of these factors lead to storm-water nature based solutions not just being applied differently within a catchment but viewed and understood differently by organisations that are working in partnership. The catchment partnerships will be better equipped to incorporate or employ nature based storm water management in the UK through this research. By understanding the factors and agents behind the development of SuDS, GI and NFM and providing ways in which to visualise and communicate this at a catchment level it is hoped to reduce some of the barriers to their practical implementation.

Determining mineral weathering rates based on solid and solute weathering gradients and velocities: Application to biotite weathering in saprolites

USGS Publications Warehouse

White, A.F.

2002-01-01

Chemical weathering gradients are defined by the changes in the measured elemental concentrations in solids and pore waters with depth in soils and regoliths. An increase in the mineral weathering rate increases the change in these concentrations with depth while increases in the weathering velocity decrease the change. The solid-state weathering velocity is the rate at which the weathering front propagates through the regolith and the solute weathering velocity is equivalent to the rate of pore water infiltration. These relationships provide a unifying approach to calculating both solid and solute weathering rates from the respective ratios of the weathering velocities and gradients. Contemporary weathering rates based on solute residence times can be directly compared to long-term past weathering based on changes in regolith composition. Both rates incorporate identical parameters describing mineral abundance, stoichiometry, and surface area. Weathering gradients were used to calculate biotite weathering rates in saprolitic regoliths in the Piedmont of Northern Georgia, USA and in Luquillo Mountains of Puerto Rico. Solid-state weathering gradients for Mg and K at Panola produced reaction rates of 3 to 6 x 10-17 mol m-2 s-1 for biotite. Faster weathering rates of 1.8 to 3.6 ?? 10-16 mol m-2 s-1 are calculated based on Mg and K pore water gradients in the Rio Icacos regolith. The relative rates are in agreement with a warmer and wetter tropical climate in Puerto Rico. Both natural rates are three to six orders of magnitude slower than reported experimental rates of biotite weathering. ?? 2002 Elsevier Science B.V. All rights reserved.
Aqueous sulfate separation by crystallization of sulfate–water clusters

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

Custelcean, Radu; Williams, Neil J.; Seipp, Charles A.

An effective approach to separating sulfates from aqueous solutions is based on the crystallization of extended [SO 4(H 2O) 5 2-] n sulfate–water clusters with a bis(guanidinium) ligand. The ligand was generated in situ by hydrazone condensation in water, thus avoiding elaborate syntheses, tedious purifications, and organic solvents. Crystallization of sulfate–water clusters represents an alternative to the now established sulfate separation strategies that involve encapsulating the “naked” anion.
Aqueous sulfate separation by crystallization of sulfate–water clusters

DOE PAGES

Custelcean, Radu; Williams, Neil J.; Seipp, Charles A.

2015-08-07

An effective approach to separating sulfates from aqueous solutions is based on the crystallization of extended [SO 4(H 2O) 5 2-] n sulfate–water clusters with a bis(guanidinium) ligand. The ligand was generated in situ by hydrazone condensation in water, thus avoiding elaborate syntheses, tedious purifications, and organic solvents. Crystallization of sulfate–water clusters represents an alternative to the now established sulfate separation strategies that involve encapsulating the “naked” anion.
Water quality monitor for recovered spacecraft water

NASA Technical Reports Server (NTRS)

Ejzak, E. M.; Price, D. F.

1985-01-01

A total organic carbon (TOC) analysis system based on ultraviolet absorption is described. The equation for measuring the intensity of the absorbed radiation of the organic substances, which is based on the Lambert-Beer law, is given; the intensity of the absorption is proportional to the concentration of the solution. The operation of the UV-Absorption analyzer, which utilizes a split beam, two wvaelength method, is studied. The influences of the cell path length and specific compounds in the solution flowing through the cell on absorbances is discussed. The performance and response of the analyzer is evaluated; good correlation is observed between the absorption value and TOC. The advantage of the UV-Absorption as compared with the UV-Oxidation are examined.
Water treatment and handwashing behaviors among non-pregnant friends and relatives of participants in an antenatal hygiene promotion program in Malawi.

PubMed

Russo, Elizabeth T; Sheth, Anandi; Menon, Manoj; Wannemuehler, Kathleen; Weinger, Merri; Kudzala, Amose C; Tauzie, Blessius; Masuku, Humphreys D; Msowoya, Tapona E; Quick, Robert

2012-05-01

Access to safe drinking water and improved hygiene are essential for preventing diarrheal diseases. To integrate hygiene improvement with antenatal care, free hygiene kits (water storage containers, water treatment solution, soap) and educational messages were distributed to pregnant women at antenatal clinics in Malawi. We assessed water treatment and hygiene practices of 275 non-pregnant friends and relatives of the hygiene kit recipients at baseline and follow-up nine months later to measure program impact on non-participants in the same communities. At follow-up, friends and relatives who did not receive kits or education were more likely than at baseline to purchase and use water treatment solution (25% versus 1%; P < 0.0001) and demonstrate correct handwashing practices (60% versus 18%; P < 0.0001). This antenatal clinic-based program resulted in improved water treatment and hygiene behaviors among non-pregnant friends and relatives living in the same communities as hygiene kit recipients, suggesting that program benefits extended beyond direct beneficiaries.
Optimal Water-Power Flow Problem: Formulation and Distributed Optimal Solution

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

Dall-Anese, Emiliano; Zhao, Changhong; Zamzam, Admed S.

This paper formalizes an optimal water-power flow (OWPF) problem to optimize the use of controllable assets across power and water systems while accounting for the couplings between the two infrastructures. Tanks and pumps are optimally managed to satisfy water demand while improving power grid operations; {for the power network, an AC optimal power flow formulation is augmented to accommodate the controllability of water pumps.} Unfortunately, the physics governing the operation of the two infrastructures and coupling constraints lead to a nonconvex (and, in fact, NP-hard) problem; however, after reformulating OWPF as a nonconvex, quadratically-constrained quadratic problem, a feasible point pursuit-successivemore » convex approximation approach is used to identify feasible and optimal solutions. In addition, a distributed solver based on the alternating direction method of multipliers enables water and power operators to pursue individual objectives while respecting the couplings between the two networks. The merits of the proposed approach are demonstrated for the case of a distribution feeder coupled with a municipal water distribution network.« less
Ground-water models for water resources planning

USGS Publications Warehouse

Moore, John E.

1980-01-01

In the past decade hydrologists have emphasized the development of computer-based mathematical models to aid in the understanding of flow, the transport of solutes, transport of heat, and deformation in the groundwater system. These models have been used to provide information and predictions for water managers. Too frequently, groundwater was neglected in water-resource planning because managers believed that it could not be adequately evaluated in terms of availability, quality, and effect of development on surface water supplies. Now, however, with newly developed digital groundwater models, effects of development can be predicted. Such models have been used to predict hydrologic and quality changes under different stresses. These models have grown in complexity over the last 10 years from simple one-layer flow models to three-dimensional simulations of groundwater flow which may include solute transport, heat transport, effects of land subsidence, and encroachment of salt water. This paper illustrates, through case histories, how predictive groundwater models have provided the information needed for the sound planning and management of water resources in the United States. (USGS)
Potatoes and Trout: Maintaining Robust Agriculture and a Healthy Trout Fishery in the Central Sands of Wisconsin

NASA Astrophysics Data System (ADS)

Fienen, M. N.; Bradbury, K. R.; Kniffin, M.; Barlow, P. M.; Krause, J.; Westenbroek, S.; Leaf, A.

2015-12-01

The well-drained sandy soil in the Wisconsin Central Sands is ideal for growing potatoes, corn, and other vegetables. A shallow sand and gravel aquifer provides abundant water for agricultural irrigation but also supplies critical base flow to cold-water trout streams. These needs compete with one another, and stakeholders from various perspectives are collaborating to seek solutions. Stakeholders were engaged in providing and verifying data to guide construction of a groundwater flow model which was used with linear and sequential linear programming to evaluate optimal tradeoffs between agricultural pumping and ecologically based minimum base flow values. The connection between individual irrigation wells as well as industrial and municipal supply and streamflow depletion can be evaluated using the model. Rather than addressing 1000s of wells individually, a variety of well management groups were established through k-means clustering. These groups are based on location, potential impact, water-use categories, depletion potential, and other factors. Through optimization, pumping rates were reduced to attain mandated minimum base flows. This formalization enables exploration of possible solutions for the stakeholders, and provides a tool which is transparent and forms a basis for discussion and negotiation.
Definition and solution of a stochastic inverse problem for the Manning's n parameter field in hydrodynamic models.

PubMed

Butler, T; Graham, L; Estep, D; Dawson, C; Westerink, J J

2015-04-01

The uncertainty in spatially heterogeneous Manning's n fields is quantified using a novel formulation and numerical solution of stochastic inverse problems for physics-based models. The uncertainty is quantified in terms of a probability measure and the physics-based model considered here is the state-of-the-art ADCIRC model although the presented methodology applies to other hydrodynamic models. An accessible overview of the formulation and solution of the stochastic inverse problem in a mathematically rigorous framework based on measure theory is presented. Technical details that arise in practice by applying the framework to determine the Manning's n parameter field in a shallow water equation model used for coastal hydrodynamics are presented and an efficient computational algorithm and open source software package are developed. A new notion of "condition" for the stochastic inverse problem is defined and analyzed as it relates to the computation of probabilities. This notion of condition is investigated to determine effective output quantities of interest of maximum water elevations to use for the inverse problem for the Manning's n parameter and the effect on model predictions is analyzed.
Definition and solution of a stochastic inverse problem for the Manning's n parameter field in hydrodynamic models

NASA Astrophysics Data System (ADS)

Butler, T.; Graham, L.; Estep, D.; Dawson, C.; Westerink, J. J.

2015-04-01

The uncertainty in spatially heterogeneous Manning's n fields is quantified using a novel formulation and numerical solution of stochastic inverse problems for physics-based models. The uncertainty is quantified in terms of a probability measure and the physics-based model considered here is the state-of-the-art ADCIRC model although the presented methodology applies to other hydrodynamic models. An accessible overview of the formulation and solution of the stochastic inverse problem in a mathematically rigorous framework based on measure theory is presented. Technical details that arise in practice by applying the framework to determine the Manning's n parameter field in a shallow water equation model used for coastal hydrodynamics are presented and an efficient computational algorithm and open source software package are developed. A new notion of "condition" for the stochastic inverse problem is defined and analyzed as it relates to the computation of probabilities. This notion of condition is investigated to determine effective output quantities of interest of maximum water elevations to use for the inverse problem for the Manning's n parameter and the effect on model predictions is analyzed.
4D-tomographic reconstruction of water vapor using the hybrid regularization technique with application to the North West of Iran

NASA Astrophysics Data System (ADS)

Adavi, Zohre; Mashhadi-Hossainali, Masoud

2015-04-01

Water vapor is considered as one of the most important weather parameter in meteorology. Its non-uniform distribution, which is due to the atmospheric phenomena above the surface of the earth, depends both on space and time. Due to the limited spatial and temporal coverage of observations, estimating water vapor is still a challenge in meteorology and related fields such as positioning and geodetic techniques. Tomography is a method for modeling the spatio-temporal variations of this parameter. By analyzing the impact of troposphere on the Global Navigation Satellite (GNSS) signals, inversion techniques are used for modeling the water vapor in this approach. Non-uniqueness and instability of solution are the two characteristic features of this problem. Horizontal and/or vertical constraints are usually used to compute a unique solution for this problem. Here, a hybrid regularization method is used for computing a regularized solution. The adopted method is based on the Least-Square QR (LSQR) and Tikhonov regularization techniques. This method benefits from the advantages of both the iterative and direct techniques. Moreover, it is independent of initial values. Based on this property and using an appropriate resolution for the model, firstly the number of model elements which are not constrained by GPS measurement are minimized and then; water vapor density is only estimated at the voxels which are constrained by these measurements. In other words, no constraint is added to solve the problem. Reconstructed profiles of water vapor are validated using radiosonde measurements.
Accuracy of water displacement hand volumetry using an ethanol and water mixture.

PubMed

Hargens, Alan R; Kim, Jong-Moon; Cao, Peihong

2014-02-01

The traditional water displacement method for measuring limb volume is improved by adding ethanol to water. Four solutions were tested (pure water, 0.5% ethanol, 3% ethanol, and 6% ethanol) to determine the most accurate method when measuring the volume of a known object. The 3% and 6% ethanol solutions significantly reduced (P < 0.001) the mean standard deviation of 10 measurements of a known sphere (390.1 +/- 0.25 mi) from 2.27 ml with pure water to 0.9 ml using the 3% alcohol solution and to 0.6 using 6% ethanol solution (the mean coefficients of variation were reduced from 0.59% for water to 0.22% for 3% ethanol and 0.16% for 6% ethanol). The spheres' volume measured with pure water, 0.5% ethanol solution, 3% ethanol solution, and 6% ethanol solution was 383.2 +/- 2.27 ml, 384.4 +/- 1.9 ml, 389.4 +/- 0.9 ml, and 390.2 +/- 0.6 ml, respectively. Using the 3% and 6% ethanol solutions to measure hand volume blindly in 10 volunteers significantly reduced the mean coefficient of variation for hand volumetry from 0.91% for water to 0.52% for the 3% ethanol solution (P < 0.05) and to 0.46% for the 6% ethanol solution (P < 0.05). The mean standard deviation from all 10 subjects decreased from 4.2 ml for water to 2.3 ml for 3% ethanol solution and 2.1 ml for the 6% solution. These findings document that the accuracy and reproducibility of hand volume measurements are improved by small additions of ethanol, most likely by reducing surface tension of water.
Removal of inorganic mercury and methylmercury from surface waters following coagulation of dissolved organic matter with metal-based salts

USGS Publications Warehouse

Henneberry, Y.K.; Kraus, T.E.C.; Fleck, J.A.; Krabbenhoft, D.P.; Bachand, P.M.; Horwath, W.R.

2011-01-01

The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. In the absence of DOM, all three coagulants released IHg into solution, however in the presence of DOM the coagulants removed up to 97% of IHg and 80% of MeHg. Results suggest that the removal of Hg is mediated by DOM-coagulant interactions. There was a preferential association of IHg with the more aromatic, higher molecular weight fraction of DOM but no such relationship was found for MeHg. This study offers new fundamental insights regarding large-scale removal of Hg at environmentally relevant regarding large-scale removal of Hg at environmentally relevant concentrations.
Study on the disparate transition behaviors of the electrical/physical properties in PEDOT:PSS film depending on solvent species under a follow-up solution-treatment process

NASA Astrophysics Data System (ADS)

Yun, Dong-Jin; Kim, Jung-Hwa; Kim, Seong Heon; Seol, Minsu; Yu, DaEun; Kwon, Hyukju; Ham, Yongnam; Chung, JaeGwan; Kim, Yongsu; Heo, Sung

2016-04-01

In most solution-processed organic devices, a poly(3,4-ethylenedioxythiophene) (PEDOT) polymerized with poly(4-styrenesulfonate) (PSS) film is inevitably affected by various conditions during the subsequent solution-coating processes. To investigate the effects of direct solvent exposure on the properties of PEDOT polymerized with PSS (PEDOT:PSS) films, photoemission spectroscopy-based analytical methods were used before and after solvent-coating processes. Our results clearly indicate that PEDOT:PSS films undergo a different transition mechanism depending on the solubility of the solvent in water. The water-miscible solvents induce the solvation of hydrophilic PSS chains. As a result, this process allows the solvent to diffuse into the PEDOT:PSS film, and a conformational change between PEDOT and PSS occurs. On the other hand, the water-immiscible organic solvents cause the partial adsorption of solvent molecules at the PE surface, which leads to changes in the surface properties, including work function. Based on our finding, we demonstrate that the energy-level alignments at the organic semiconductor/electrode interface for the PEDOT:PSS films can be controlled by simple solvent treatments.
The Effect of Low-GDP Solution on Ultrafiltration and Solute Transport in Continuous Ambulatory Peritoneal Dialysis Patients

PubMed Central

Cho, Kyu-Hyang; Do, Jun-Young; Park, Jong-Won; Yoon, Kyung-Woo; Kim, Yong-Lim

2013-01-01

♦ Background: Several studies have reported benefits for human peritoneal mesothelial cell function of a neutral-pH dialysate low in glucose degradation products (GDPs). However, the effects of low-GDP solution on ultrafiltration (UF), transport of solutes, and control of body water remain elusive. We therefore investigated the effect of low-GDP solution on UF, solute transport, and control of body water. ♦ Methods: Among 79 new continuous ambulatory peritoneal dialysis (CAPD) patients, 60 completed a 12-month protocol (28 in a lactate-based high-GDP solution group, 32 in a lactate-based low-GDP solution group). Clinical indices—including 24-hour UF volume (UFV), 24-hour urine volume (UV), residual renal function, and dialysis adequacy—were measured at months 1, 6, and 12. At months 1, 6, and 12, UFV, glucose absorption, 4-hour dialysate-to-plasma (D/P) creatinine, and 1-hour D/P Na+ were assessed during a modified 4.25% peritoneal equilibration test (PET). Body composition by bioelectric impedance analysis was measured at months 1 and 12 in 26 CAPD patients. ♦ Results: Daily UFV was lower in the low-GDP group. Despite similar solute transport and aquaporin function, the low-GDP group also showed lower UFV and higher glucose absorption during the PET. Factors associated with UFV during the PET were lactate-based high-GDP solution and 1-hour D/P Na+. No differences in volume status and obesity at month 12 were observed, and improvements in hypervolemia were equal in both groups. ♦ Conclusions: Compared with the high-GDP group, the low-GDP group had a lower UFV during a PET and a lower daily UFV during the first year after peritoneal dialysis initiation. Although the low-GDP group had a lower daily UFV, no difficulties in controlling edema were encountered. PMID:23284074
Synergistic effects of water addition and step heating on the formation of solution-processed zinc tin oxide thin films: towards high-mobility polycrystalline transistors

NASA Astrophysics Data System (ADS)

Huang, Genmao; Duan, Lian; Zhao, Yunlong; Zhang, Yunge; Dong, Guifang; Zhang, Deqiang; Qiu, Yong

2016-11-01

Thin-film transistors (TFTs) with high mobility and good uniformity are attractive for next-generation flat panel displays. In this work, solution-processed polycrystalline zinc tin oxide (ZTO) thin film with well-ordered microstructure is prepared, thanks to the synergistic effect of water addition and step heating. The step heating treatment other than direct annealing induces crystallization, while adequate water added to precursor solution further facilitates alloying and densification process. The optimal polycrystalline ZTO film is free of hierarchical sublayers, and featured with an increased amount of ternary phases, as well as a decreased fraction of oxygen vacancies and hydroxides. TFT devices based on such an active layer exhibit a remarkable field-effect mobility of 52.5 cm2 V-1 s-1, a current on/off ratio of 2 × 105, a threshold voltage of 2.32 V, and a subthreshold swing of 0.36 V dec-1. Our work offers a facile method towards high-performance solution-processed polycrystalline metal oxide TFTs.
Assessments of quaternary ammonium compounds (QAC) for in-water treatment of mussel fouling in vessel internals and sea chests using an experimental seawater pipework system.

PubMed

Piola, Richard; Grandison, Clare

2017-01-01

The primary in-water emergency treatment method for mussel fouling of internal seawater systems of Royal Australian Navy vessels is to flush with a 1% detergent solution containing quaternary ammonium compounds (QAC). Parameters for application of this treatment are based on previous research; however, much of the research has been conducted at small-scales under controlled laboratory conditions. This study examined the efficacy of QAC solutions for treating mussel biofouling under realistic field conditions using experimental seawater piping systems. The efficacy of QAC solutions was highly dependent on the size of mussels present. Chemical treatments comprising 1, 2 and 5% v v -1 QAC solution were effective at killing large (50-92 mm) mussels in the pipework and sea chest of the system following 24 h exposure. In contrast, small mussels (10-30 mm) appeared resilient to the majority of treatment regimes. Differences in water temperature, DO and pH during dosing had no discernible impact on treatment efficacy.
Application of precipitation methods for the production of water-insoluble drug nanocrystals: production techniques and stability of nanocrystals.

PubMed

Xia, Dengning; Gan, Yong; Cui, Fude

2014-01-01

This review focuses on using precipitation (bottom-up) method to produce water-insoluble drug nanocrystals, and the stability issues of nanocrystals. The precipitation techniques for production of ultra-fine particles have been widely researched for last few decades. In these techniques, precipitation of solute is achieved by addition of a non-solvent for solute called anti-solvent to decrease the solvent power for the solute dissolved in a solution. The anti-solvent can be water, organic solvents or supercritical fluids. In this paper, efforts have been made to review the precipitation techniques involving the anti-solvent precipitation by simple mixing, impinging jet mixing, multi-inlet vortex mixing, the using of high-gravity, ultrasonic waves and supercritical fluids. The key to the success of yielding stable nanocrystals in these techniques is to control the nucleation kinetics and particle growth through mixing during precipitation based on crystallization theories. The stability issues of the nanocrystals, such as sedimentation, Ostwald ripening, agglomeration and cementing of crystals, change of crystalline state, and the approaches to stabilizing nanocrystals are also discussed in detail.
Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

DOE PAGES

Wang, Lei; Yan, Danhua; Shaffer, David W.; ...

2017-12-27

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less
Improved Stability and Performance of Visible Photoelectrochemical Water Splitting on Solution-Processed Organic Semiconductor Thin Films by Ultrathin Metal Oxide Passivation

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

Wang, Lei; Yan, Danhua; Shaffer, David W.

Solution-processable organic semiconductors have potentials as visible photoelectrochemical (PEC) water splitting photoelectrodes due to their tunable small band gap and electronic energy levels, but they are typically limited by poor stability and photocatalytic activity. In this study, we demonstrate the direct visible PEC water oxidation on solution-processed organic semiconductor thin films with improved stability and performance by ultrathin metal oxide passivation layers. N-type fullerene-derivative thin films passivated by sub-2 nm ZnO via atomic layer deposition enabled the visible PEC water oxidation at wavelengths longer than 600 nm in harsh alkaline electrolyte environments with up to 30 μA/cm 2 photocurrents atmore » the thermodynamic water-oxidation equilibrium potential and the photoanode half-lifetime extended to ~1000 s. The systematic investigation reveals the enhanced water oxidation catalytic activity afforded by ZnO passivation and the charge tunneling governing the hole transfer through passivation layers. Further enhanced PEC performances were realized by improving the bottom ohmic contact to the organic semiconductor, achieving ~60 μA/cm 2 water oxidation photocurrent at the equilibrium potential, the highest values reported for organic semiconductor thin films to our knowledge. The improved stability and performance of passivated organic photoelectrodes and discovered design rationales provide useful guidelines for realizing the stable visible solar PEC water splitting based on organic semiconductor thin films.« less

Fully- and weakly-nonlinear biperiodic traveling waves in shallow water

NASA Astrophysics Data System (ADS)

Hirakawa, Tomoaki; Okamura, Makoto

2018-04-01

We directly calculate fully nonlinear traveling waves that are periodic in two independent horizontal directions (biperiodic) in shallow water. Based on the Riemann theta function, we also calculate exact periodic solutions to the Kadomtsev-Petviashvili (KP) equation, which can be obtained by assuming weakly-nonlinear, weakly-dispersive, weakly-two-dimensional waves. To clarify how the accuracy of the biperiodic KP solution is affected when some of the KP approximations are not satisfied, we compare the fully- and weakly-nonlinear periodic traveling waves of various wave amplitudes, wave depths, and interaction angles. As the interaction angle θ decreases, the wave frequency and the maximum wave height of the biperiodic KP solution both increase, and the central peak sharpens and grows beyond the height of the corresponding direct numerical solutions, indicating that the biperiodic KP solution cannot qualitatively model direct numerical solutions for θ ≲ 45^\\circ . To remedy the weak two-dimensionality approximation, we apply the correction of Yeh et al (2010 Eur. Phys. J. Spec. Top. 185 97-111) to the biperiodic KP solution, which substantially improves the solution accuracy and results in wave profiles that are indistinguishable from most other cases.
Solutions Network Formulation Report. The Potential Contributions of the Global Precipitation Measurement Mission to Estuary Management in Acadia National Park

NASA Technical Reports Server (NTRS)

Anderson, Daniel; Hilbert, Kent; Lewis, David

2007-01-01

This candidate solution suggests the use of GPM precipitation observations to enhance the Acadia National Park NLERDSS. Simulated GPM data should provide measurements that would enable analysis of how precipitation affects runoff and nutrient load in the park?s wetlands. This solution benefits society by aiding park and resource managers in making predictions based on hypothetical changes and in identifying effective mitigation scenarios. This solution supports the Coastal Management, Water Management, and Ecological Forecasting National Applications.
Biological plywood film formation from para-nematic liquid crystalline organization.

PubMed

Aguilar Gutierrez, Oscar F; Rey, Alejandro D

2017-11-15

In vitro non-equilibrium chiral phase ordering processes of biomacromolecular solutions offer a systematic and reproducible way of generating material architectures found in Nature, such as biological plywoods. Accelerated progress in biomimetic engineering of mesoscopic plywoods and other fibrous structures requires a fundamental understanding of processing and transport principles. In this work we focus on collagen I based materials and structures to find processing conditions that lead to defect-free collagen films displaying the helicoidal plywood architecture. Here we report experimentally-guided theory and simulations of the chiral phase ordering of collagen molecules through water solvent evaporation of pre-aligned dilute collagen solutions. We develop, implement and a posteriori validate an integrated liquid crystal chiral phase ordering-water transport model that captures the essential features of spatio-temporal chiral structure formation in shrinking film domains due to directed water loss. Three microstructural (texture) modes are identified depending on the particular value of the time-scale ratio defined by collagen rotational diffusion to water translational diffusion. The magnitude of the time scale ratio provides the conditions for the synchronization of the helical axis morphogenesis with the increase in the mesogen concentration due to water loss. Slower than critical water removal rates leads to internal multiaxial cellular patterns, reminiscent of the classical columnar-equiaxed metallurgical casting structures. Excessive water removal rates lead to destabilization of the chiral axis and multidomain defected films. The predictions of the integrated model are in qualitative agreement with experimental results and can potentially guide solution processing of other bio-related mesogenic solutions that seek to mimic the architecture of biological fibrous composites.
Taste and odor occurrence in Lake William C. Bowen and Municipal Reservoir #1, Spartanburg County, South Carolina

USGS Publications Warehouse

Journey, Celeste; Arrington, Jane M.

2009-01-01

The U.S. Geological Survey and Spartanburg Water are working cooperatively on an ongoing study of Lake Bowen and Reservoir #1 to identify environmental factors that enhance or influence the production of geosmin in the source-water reservoirs. Spartanburg Water is using information from this study to develop management strategies to reduce (short-term solution) and prevent (long-term solution) geosmin occurrence. Spartanburg Water utility treats and distributes drinking water to the Spartanburg area of South Carolina. The drinking water sources for the area are Lake William C. Bowen (Lake Bowen) and Municipal Reservoir #1 (Reservoir #1), located north of Spartanburg. These reservoirs, which were formed by the impoundment of the South Pacolet River, were assessed in 2006 by the South Carolina Department of Health and Environmental Control (SCDHEC) as being fully supportive of all uses based on established criteria. Nonetheless, Spartanburg Water had noted periodic taste and odor problems due to the presence of geosmin, a naturally occurring compound in the source water. Geosmin is not harmful, but its presence in drinking water is aesthetically unpleasant.
Gibbs Free Energy of Hydrolytic Water Molecule in Acyl-Enzyme Intermediates of a Serine Protease: A Potential Application for Computer-Aided Discovery of Mechanism-Based Reversible Covalent Inhibitors.

PubMed

Masuda, Yosuke; Yamaotsu, Noriyuki; Hirono, Shuichi

2017-01-01

In order to predict the potencies of mechanism-based reversible covalent inhibitors, the relationships between calculated Gibbs free energy of hydrolytic water molecule in acyl-trypsin intermediates and experimentally measured catalytic rate constants (k cat ) were investigated. After obtaining representative solution structures by molecular dynamics (MD) simulations, hydration thermodynamics analyses using WaterMap™ were conducted. Consequently, we found for the first time that when Gibbs free energy of the hydrolytic water molecule was lower, logarithms of k cat were also lower. The hydrolytic water molecule with favorable Gibbs free energy may hydrolyze acylated serine slowly. Gibbs free energy of hydrolytic water molecule might be a useful descriptor for computer-aided discovery of mechanism-based reversible covalent inhibitors of hydrolytic enzymes.
Enhancing Pre-Service Elementary Teachers' Conceptual Understanding of Solution Chemistry with Conceptual Change Text

ERIC Educational Resources Information Center

Calik, Muammer; Ayas, Alipasa; Coll, Richard Kevin

2007-01-01

This paper reports on the use of a constructivist-based pedagogy to enhance understanding of some features of solution chemistry. Pre-service science teacher trainees' prior knowledge about the dissolution of salts and sugar in water were elicited by the use of a simple diagnostic tool. The test revealed widespread alternative conceptions. These…
Direct sensing of fluoride in aqueous solutions using a boronic acid based sensor.

PubMed

Wu, Xin; Chen, Xuan-Xuan; Song, Bing-Nan; Huang, Yan-Jun; Ouyang, Wen-Juan; Li, Zhao; James, Tony D; Jiang, Yun-Bao

2014-11-21

Binding of the fluoride ion triggers aggregation of a pyreneboronic acid-catechol ensemble in acidic aqueous solutions, giving rise to intense excimer emission, allowing for sensitive fluoride ion sensing at ppm levels, with an apparent fluoride binding constant higher than 10(3) M(-1) which is unprecedented for boronic acid sensors in water.
Hydrodynamics and Water Quality forecasting over a Cloud Computing environment: INDIGO-DataCloud

NASA Astrophysics Data System (ADS)

Aguilar Gómez, Fernando; de Lucas, Jesús Marco; García, Daniel; Monteoliva, Agustín

2017-04-01

Algae Bloom due to eutrophication is an extended problem for water reservoirs and lakes that impacts directly in water quality. It can create a dead zone that lacks enough oxygen to support life and it can also be human harmful, so it must be controlled in water masses for supplying, bathing or other uses. Hydrodynamic and Water Quality modelling can contribute to forecast the status of the water system in order to alert authorities before an algae bloom event occurs. It can be used to predict scenarios and find solutions to reduce the harmful impact of the blooms. High resolution models need to process a big amount of data using a robust enough computing infrastructure. INDIGO-DataCloud (https://www.indigo-datacloud.eu/) is an European Commission funded project that aims at developing a data and computing platform targeting scientific communities, deployable on multiple hardware and provisioned over hybrid (private or public) e-infrastructures. The project addresses the development of solutions for different Case Studies using different Cloud-based alternatives. In the first INDIGO software release, a set of components are ready to manage the deployment of services to perform N number of Delft3D simulations (for calibrating or scenario definition) over a Cloud Computing environment, using the Docker technology: TOSCA requirement description, Docker repository, Orchestrator, AAI (Authorization, Authentication) and OneData (Distributed Storage System). Moreover, the Future Gateway portal based on Liferay, provides an user-friendly interface where the user can configure the simulations. Due to the data approach of INDIGO, the developed solutions can contribute to manage the full data life cycle of a project, thanks to different tools to manage datasets or even metadata. Furthermore, the cloud environment contributes to provide a dynamic, scalable and easy-to-use framework for non-IT experts users. This framework is potentially capable to automatize the processing of forecasting applying periodic tasks. For instance, a user can forecast every month the hydrodynamics and water quality status of a reservoir starting from a base model and supplying new data gathered from the instrumentation or observations. This interactive presentation aims to show the use of INDIGO solutions in a particular forecasting use case and to inspire others in the use of a Cloud framework for their applications.
A Novel Multi-Charged Draw Solute That Removes Organic Arsenicals from Water in a Hybrid Membrane Process.

PubMed

Ge, Qingchun; Lau, Cher Hon; Liu, Minghua

2018-03-20

The potential of forward osmosis for water treatment can only be maximized with suitable draw solutes. Here a three-dimensional, multicharge draw solute of decasodium phytate (Na 10 -phytate) is designed and synthesized for removing organic arsenicals from water using a hybrid forward osmosis (FO) - membrane distillation (MD) process. Efficient water recovery is achieved using Na 10 -phytate as a draw solute with a water flux of 20.0 LMH and negligible reverse solute diffusion when 1000 ppm organic arsenicals as the feed and operated under ambient conditions with FO mode. At 50 °C, the novel draw solute increases water flux by more than 30% with water fluxes higher than 26.0 LMH on the FO side, drastically enhancing water recovery efficiency. By combining the FO and MD processes into a single hybrid process, a 100% recovery of Na 10 -phytate draw solute was achieved. Crucially, organic arsenicals or Na 10 -phytate draw solutes are both rejected 100% and not detected in the permeate of the hybrid process. The complete rejection of both organic arsenicals and draw solutes using hybrid membrane processes is unprecedented; creating a new application for membrane separations.
Production of high specific activity silicon-32

DOEpatents

Phillips, Dennis R.; Brzezinski, Mark A.

1994-01-01

A process for preparation of silicon-32 is provide and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.
High specific activity silicon-32

DOEpatents

Phillips, Dennis R.; Brzezinski, Mark A.

1996-01-01

A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution to from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidization state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.
High specific activity silicon-32

DOEpatents

Phillips, D.R.; Brzezinski, M.A.

1996-06-11

A process for preparation of silicon-32 is provided and includes contacting an irradiated potassium chloride target, including spallation products from a prior irradiation, with sufficient water, hydrochloric acid or potassium hydroxide to form a solution, filtering the solution, adjusting pH of the solution from about 5.5 to about 7.5, admixing sufficient molybdate-reagent to the solution to adjust the pH of the solution to about 1.5 and to form a silicon-molybdate complex, contacting the solution including the silicon-molybdate complex with a dextran-based material, washing the dextran-based material to remove residual contaminants such as sodium-22, separating the silicon-molybdate complex from the dextran-based material as another solution, adding sufficient hydrochloric acid and hydrogen peroxide to the solution to prevent reformation of the silicon-molybdate complex and to yield an oxidation state of the molybdate adapted for subsequent separation by an anion exchange material, contacting the solution with an anion exchange material whereby the molybdate is retained by the anion exchange material and the silicon remains in solution, and optionally adding sufficient alkali metal hydroxide to adjust the pH of the solution to about 12 to 13. Additionally, a high specific activity silicon-32 product having a high purity is provided.
Water-soluble polymers for recovery of metal ions from aqueous streams

DOEpatents

Smith, Barbara F.; Robison, Thomas W.

1998-01-01

A process of selectively separating a target metal contained in an aqueous solution by contacting the aqueous solution containing a target metal with an aqueous solution including a water-soluble polymer capable of binding with the target metal for sufficient time whereby a water-soluble polymer-target metal complex is formed, and, separating the solution including the water-soluble polymer-target metal complex from the solution is disclosed.
Real-time surveillance system for marine environment based on HLIF LiDAR

NASA Astrophysics Data System (ADS)

Babichenko, Sergey; Sobolev, Innokenti; Aleksejev, Valeri; Sõro, Oliver

2017-10-01

The operational monitoring of the risk areas of marine environment requires cost-effective solutions. One of the options is the use of sensor networks based on fixed installations and moving platforms (coastal boats, supply-, cargo-, and passenger vessels). Such network allows to gather environmental data in time and space with direct links to operational activities in the controlled area for further environmental risk assessment. Among many remote sensing techniques the LiDAR (Light Detection And Ranging) based on Light Induced Fluorescence (LIF) is the tool of direct assessment of water quality variations caused by chemical pollution, colored dissolved organic matter, and phytoplankton composition. The Hyperspectral LIF (HLIF) LiDAR acquires comprehensive LIF spectra and analyses them by spectral pattern recognition technique to detect and classify the substances in water remotely. Combined use of HLIF LiDARs with Real-Time Data Management System (RTDMS) provides the economically effective solution for the regular monitoring in the controlled area. OCEAN VISUALS in cooperation with LDI INNOVATION has developed Oil in Water Locator (OWL™) with RTDMS (OWL MAP™) based on HLIF LiDAR technique. This is a novel technical solution for monitoring of marine environment providing continuous unattended operations. OWL™ has been extensively tested on board of various vessels in the North Sea, Norwegian Sea, Barents Sea, Baltic Sea and Caribbean Sea. This paper describes the technology features, the results of its operational use in 2014-2017, and outlook for the technology development.
Preparation and optimization of submicron chitosan capsules by water-based electrospraying for food and bioactive packaging applications.

PubMed

Sreekumar, Sruthi; Lemke, Philipp; Moerschbacher, Bruno M; Torres-Giner, Sergio; Lagaron, Jose M

2017-10-01

In the present study, a well-defined set of chitosans, with different degrees of acetylation (DA) and degrees of polymerization (DP), were processed by solution electrospraying from a water-based solvent. The solution properties, in terms of surface tension, conductivity, viscosity, and pH, were characterized and related to the physico-chemical properties of the chitosans. It was observed that both DA and DP values of a given chitosan, in combination with biopolymer concentration, mainly determined solution viscosity. This was, in turn, the major driving factor that defined the electrosprayability of chitosan. In addition, the physico-chemical properties of chitosans highly influenced solution conductivity and results indicated that the chitosan solutions with low or low-to-medium values of conductivity were the most optimal for electrospraying. The results obtained here also demonstrate that a good process control can be achieved by adjusting the working conditions, i.e. applied voltage, flow-rate, and tip-to-collector distance. Finally, it was also shown that electrosprayability of chitosan with inadequate physico-chemical properties can be improved by solution mixing of very different kinds of this polysaccharide. The resultant electrosprayed submicron chitosan capsules can be applied for encapsulation of food additives and to develop bioactive coatings of interest in food packaging, where these particles alone or containing functional ingredients can be released from the package into the food to promote a health benefit.
Sorption of aromatic organic pollutants to grasses from water

USGS Publications Warehouse

Barbour, J.P.; Smith, J.A.; Chiou, C.T.

2005-01-01

The influence of plant lipids on the equilibrium sorption of three aromatic solutes from water was studied. The plant-water sorption isotherms of benzene, 1,2-dichlorobenzene, and phenanthrene were measured over a large range of solute concentrations using sealed vessels containing water, dried plant material, and solute. The plant materials studied include the shoots of annual rye, tall fescue, red fescue, and spinach as well as the roots of annual rye. Seven out of eight sorption isotherms were linear with no evidence of competitive effects between the solutes. For a given plant type, the sorption coefficient increased with decreasing solute water solubility. For a given solute, sorption increased with increasing plant lipid content. The estimated lipid-water partition coefficients of individual solutes were found to be significantly greater than the corresponding octanol-water partition coefficients. This indicates that plant lipids are a more effective partition solvent than octanol for the studied aromatic compounds. As expected, the solute lipid-water partition coefficients were log-linearly related to the respective water solubilities. For the compounds studied, partitioning into the lipids is believed to be the primary sorption mechanism. ?? 2005 American Chemical Society.
Ab initio assessment of Bi1-xRExCuOS (RE = La, Gd, Y, Lu) solid solutions as a semiconductor for photochemical water splitting.

PubMed

Lardhi, Sheikha; Curutchet, Antton; Cavallo, Luigi; Harb, Moussab; Le Bahers, Tangui

2017-05-17

The investigation of the BiCuOCh (Ch = S, Se and Te) semiconductor family for thermoelectric or photovoltaic materials is a topic of increasing research interest. These materials can also be considered for photochemical water splitting if one representative having a bandgap, E g , at around 2 eV can be developed. With this aim, we simulated the solid solutions Bi 1-x RE x CuOS (RE = Y, La, Gd and Lu) from pure BiCuOS (E g ∼ 1.1 eV) to pure RECuOS compositions (E g ∼ 2.9 eV) by DFT calculations based on the HSE06 range-separated hybrid functional with the inclusion of spin-orbit coupling. Starting from the thermodynamic stability of the solid solution, several properties were computed for each system including bandgaps, dielectric constants, effective masses and exciton binding energies. We discussed the variation of these properties based on the relative organization of Bi and RE atoms in their common sublattice to offer a physical understanding of the influence of the RE doping of BiCuOS. Some compositions were found to give appropriate properties for water splitting applications. Furthermore, we found that at low RE fractions the transport properties of BiCuOS are improved that can find applications beyond water splitting.
Preferential solvation, ion pairing, and dynamics of concentrated aqueous solutions of divalent metal nitrate salts

NASA Astrophysics Data System (ADS)

Yadav, Sushma; Chandra, Amalendu

2017-12-01

We have investigated the characteristics of preferential solvation of ions, structure of solvation shells, ion pairing, and dynamics of aqueous solutions of divalent alkaline-earth metal nitrate salts at varying concentration by means of molecular dynamics simulations. Hydration shell structures and the extent of preferential solvation of the metal and nitrate ions in the solutions are investigated through calculations of radial distribution functions, tetrahedral ordering, and also spatial distribution functions. The Mg2+ ions are found to form solvent separated ion-pairs while the Ca2+ and Sr2+ ions form contact ion pairs with the nitrate ions. These findings are further corroborated by excess coordination numbers calculated through Kirkwood-Buff G factors for different ion-ion and ion-water pairs. The ion-pairing propensity is found to be in the order of Mg(NO3) 2 < C a (NO3) 2 < S r (NO3) 2, and it follows the trend given by experimental activity coefficients. It is found that proper modeling of these solutions requires the inclusion of electronic polarization of the ions which is achieved in the current study through electronic continuum correction force fields. A detailed analysis of the effects of ion-pairs on the structure and dynamics of water around the hydrated ions is done through classification of water into different subspecies based on their locations around the cations or anions only or bridged between them. We have looked at the diffusion coefficients, relaxation of orientational correlation functions, and also the residence times of different subspecies of water to explore the dynamics of water in different structural environments in the solutions. The current results show that the water molecules are incorporated into fairly well-structured hydration shells of the ions, thus decreasing the single-particle diffusivities and increasing the orientational relaxation times of water with an increase in salt concentration. The different structural motifs also lead to the presence of substantial dynamical heterogeneity in these solutions of strongly interacting ions. The current study helps us to understand the molecular details of hydration structure, ion pairing, and dynamics of water in the solvation shells and also of ion diffusion in aqueous solutions of divalent metal nitrate salts.
Ge/Si Ratios Record the Impact of Forest Conversion to Cropland on Soil Chemical Weathering Processes and Solutes Export to Rivers

NASA Astrophysics Data System (ADS)

Ameijeiras-Marino, Y.; Opfergelt, S.; Derry, L. A.; Robinet, J.; Delmelle, P.

2016-12-01

Soil weathering processes influence solute fluxes to rivers, playing a major role in global biogeochemical cycles. Land use change such as forest conversion to cropland enhances soil erosion, which mobilizes solutes and exposes new mineral surfaces to weathering processes, changing soil weathering degree. However, the impact of forest conversion to cropland on soil weathering degree and solute fluxes exported from soils to rivers remain poorly quantified. This study assesses the soil weathering degree and uses a geochemical tracer of weathering, Ge/Si ratio, to provide new insights on the impact of soil weathering processes under anthropogenic forcing on the transfer of solutes to rivers. A subtropical site was studied in Rio Grande do Sul (Brazil). This area is characterized by mean annual rainfall of 1800 mm, with strong rain events mobilizing high sediment load. A forested catchment is considered as the reference and compared to a catchment cultivated for the past 100 years (similar lithology and climate). Bedrock, soil, soil pore water and stream water (during base flow and rain events) samples were analysed for their chemical and mineralogical compositions and Ge/Si ratios (combined isotope dilution, HR-ICP-MS and hydride generation). Chemical and mineralogical analyses highlight that forest conversion to cropland decreases the soil weathering degree on steep slopes. Ge/Si ratios (μmol/mol) are comparable in bulk soils between the forested (2.33 ± 0.50) and the cultivated catchment (2.61 ± 0.62), but differ in soil pore waters between forest (0.47 ± 0.16) and culture (0.73 ± 0.15) indicating differences on soil weathering processes. The response of Ge/Si ratios in stream waters to a rain event differs between forest and culture, highlighting a larger contribution from soil pore waters to stream waters under culture. Altogether, our data support that land use history has an impact on the present day soil weathering processes and on the solute export to rivers.
Multiphase flow experiments, mathematical modeling and numerical simulation of the water - gas - solute movement

NASA Astrophysics Data System (ADS)

Li, Y.; Ma, X.; Su, N.

2013-12-01

The movement of water and solute into and through the vadose zone is, in essence, an issue of immiscible displacement in pore-space network of a soil. Therefore, multiphase flow and transport in porous media, referring to three medium: air, water, and the solute, pose one of the largest unresolved challenges for porous medium fluid seepage. However, this phenomenon has always been largely neglected. It is expected that a reliable analysis model of the multi-phase flow in soil can truly reflect the process of natural movement about the infiltration, which is impossible to be observed directly. In such cases, geophysical applications of the nuclear magnetic resonance (NMR) provides the opportunity to measure the water movements into soils directly over a large scale from tiny pore to regional scale, accordingly enable it available both on the laboratory and on the field. In addition, the NMR provides useful information about the pore space properties. In this study, we proposed both laboratory and field experiments to measure the multi-phase flow parameters, together with optimize the model in computer programming based on the fractional partial differential equations (fPDE). In addition, we establish, for the first time, an infiltration model including solute flowing with water, which has huge influence on agriculture and soil environment pollution. Afterwards, with data collected from experiments, we simulate the model and analyze the spatial variability of parameters. Simulations are also conducted according to the model to evaluate the effects of airflow on water infiltration and other effects such as solute and absorption. It has significant meaning to oxygen irrigation aiming to higher crop yield, and shed more light into the dam slope stability. In summary, our framework is a first-time model added in solute to have a mathematic analysis with the fPDE and more instructive to agriculture activities.

Roles of Bi, M and VO{sub 4} tetrahedron in photocatalytic properties of novel Bi{sub 0.5}M{sub 0.5}VO{sub 4} (M=La, Eu, Sm and Y) solid solutions for overall water splitting

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

Liu Hui; Research Center for Combustion and Environment Technology, Shanghai Jiao Tong University, shanghai 200240; Faculty of Engineering Sciences, Kyushu University, Fukuoka 816-8580

2012-02-15

Novel Bi{sub 0.5}M{sub 0.5}VO{sub 4} (BMV; M=La, Eu, Sm and Y) solid solutions were prepared and studied in this paper. All the samples were proved to produce H{sub 2} and O{sub 2} simultaneously from pure water under the irradiation of UV light. M-O bond lengths were proved to increase with M cations by refining cell parameters and atomic positions. Besides, band gaps, energy gaps and photocatalytic activities of BMV also changed with M cations. Both of M-O and V-O bond lengths were suggested to account for this phenomenon. Inactive A{sub 0.5}Y{sub 0.5}VO{sub 4} (A=La, Ce) for water splitting proved incorporationmore » of Bi rather than distortion of VO{sub 4} tetrahedron was a critical factor for improving efficiency of overall water splitting by facilitating the generation of electron and hole with lighter effective masses. Replacement of Bi by M cations not only gave indirect effect on band structure but also raised position of conduction band minimum to meet requirement of H{sub 2} production. - Graphical abstract: Novel Bi{sub 0.5}M{sub 0.5}VO{sub 4} (M=La, Eu, Sm and Y) solid solutions showed the high and stable photocatalytic activities for overall water splitting with their crystal radii of M elements. Highlights: Black-Right-Pointing-Pointer BMV solid solutions were novel highly efficient V-based photocatalysts for overall water splitting. Black-Right-Pointing-Pointer Photocatalytic activity of BMV solid solution related to the effective ionic radii of M cations. Black-Right-Pointing-Pointer Incorporation of Bi is one of key factors for the highly efficient activity of BMV solid solution. Black-Right-Pointing-Pointer Incorporation of Y is dispensable for H{sub 2} production.« less
Aqueous corrosion of phosphide minerals from iron meteorites: a highly reactive source of prebiotic phosphorus on the surface of the early Earth.

PubMed

Pasek, Matthew A; Lauretta, Dante S

2005-08-01

We present the results of an experimental study of aqueous corrosion of Fe-phosphide under conditions relevant to the early Earth. The results strongly suggest that iron meteorites were an important source of reactive phosphorus (P), a requirement for the formation of P-based life. We further demonstrate that iron meteorites were an abundant source of phosphide minerals early in Earth history. Phosphide corrosion was studied in five different solutions: deionized water, deionized water buffered with sodium bicarbonate, deionized water with dissolved magnesium and calcium chlorides, deionized water containing ethanol and acetic acid, and deionized water containing the chlorides, ethanol, and acetic acid. Experiments were performed in the presence of both air and pure Ar gas to evaluate the effect of atmospheric chemistry. Phosphide corrosion in deionized water results in a metastable mixture of mixed-valence, P-bearing ions including pyrophosphate and triphosphate, key components for metabolism in modern life. In a pH-buffered solution of NaHCO(3), the condensed and reduced species diphosphonate is an abundant corrosion product. Corrosion in ethanol- and acetic acid-containing solutions yields additional P-bearing organic molecules, including acetyl phosphonate and a cyclic triphosphorus molecule. Phosphonate is a major corrosion product of all experiments and is the only P-bearing molecule that persists in solutions with high concentrations of magnesium and calcium chlorides, which suggests that phosphonate may have been a primitive oceanic source of P. The stability and reactivity of phosphonate and hypophosphite in solution were investigated to elucidate reaction mechanisms and the role of mineral catalysts on P-solution chemistry. Phosphonate oxidation is rapid in the presence of Fe metal but negligible in the presence of magnetite and in the control sample. The rate of hypophosphite oxidation is independent of reaction substrate.
An image-based reaction field method for electrostatic interactions in molecular dynamics simulations of aqueous solutions

NASA Astrophysics Data System (ADS)

Lin, Yuchun; Baumketner, Andrij; Deng, Shaozhong; Xu, Zhenli; Jacobs, Donald; Cai, Wei

2009-10-01

In this paper, a new solvation model is proposed for simulations of biomolecules in aqueous solutions that combines the strengths of explicit and implicit solvent representations. Solute molecules are placed in a spherical cavity filled with explicit water, thus providing microscopic detail where it is most needed. Solvent outside of the cavity is modeled as a dielectric continuum whose effect on the solute is treated through the reaction field corrections. With this explicit/implicit model, the electrostatic potential represents a solute molecule in an infinite bath of solvent, thus avoiding unphysical interactions between periodic images of the solute commonly used in the lattice-sum explicit solvent simulations. For improved computational efficiency, our model employs an accurate and efficient multiple-image charge method to compute reaction fields together with the fast multipole method for the direct Coulomb interactions. To minimize the surface effects, periodic boundary conditions are employed for nonelectrostatic interactions. The proposed model is applied to study liquid water. The effect of model parameters, which include the size of the cavity, the number of image charges used to compute reaction field, and the thickness of the buffer layer, is investigated in comparison with the particle-mesh Ewald simulations as a reference. An optimal set of parameters is obtained that allows for a faithful representation of many structural, dielectric, and dynamic properties of the simulated water, while maintaining manageable computational cost. With controlled and adjustable accuracy of the multiple-image charge representation of the reaction field, it is concluded that the employed model achieves convergence with only one image charge in the case of pure water. Future applications to pKa calculations, conformational sampling of solvated biomolecules and electrolyte solutions are briefly discussed.
[Determination of Chloride Salt Solution by NIR Spectroscopy].

PubMed

Zhang, Bin; Chen, Jian-hong; Jiao, Ming-xing

2015-07-01

Determination of chloride salt solution by near infrared spectrum plays a very important role in Biomedicine. The near infrared spectrum analysis of Sodium chloride, potassium chloride, calcium chloride aqueous solution shows that the concentration change of chloride salt can affect hydrogen bond, resulting in the variation of near infrared spectrum of water. The temperature influence on NIR spectrum has been decreased by choosing reasonable wavelength range and the wavelength where the temperature effects are zero (isosbestic point). Chlorine salt prediction model was established based on partial least squares method and used for predicting the concentration of the chlorine ion. The impact on near infrared spectrum of the cation ionic radius, the number of ionic charge, the complex effect of ionic in water has also discussed in this article and the reason of every factor are analysed. Experimental results show that the temperature and concentration will affect the near-infrared spectrum of the solution, It is found that the effect of temperature plays the dominant role at low concentrations of chlorine salt; rather, the ionic dominates at high concentration. Chloride complexes are formed in aqueous solution, It has an effect on hydrogen bond of water combining with the cations in chlorine salt solution, Comparing different chloride solutions at the same concentration, the destruction effects of chloride complexes and catnions on the hydrogen bond of water increases in the sequences: CaCl2 >NaCl>KC. The modeling result shows that the determination coefficients (R2) = 99.97%, the root mean square error of cross validation (RM- SECV) = 4.51, and the residual prediction deviation (RPD) = 62.7, it meets the daily requirements of biochemical detection accuracy.
Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

PubMed

In, Byunggyu; Hwang, Gi Won; Lee, Keun-Hyeung

2016-09-15

A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions. The detection limit (230nM, 5.98ppb) of the peptide-based sensor was much lower than the maximum allowable level (7.41μM) of aluminium ions in drinking water demanded by EPA. The binding mode of the peptide sensor with aluminium ions was characterized using ESI mass spectrometry, NMR titration, and pH titration experiments. Copyright © 2016 Elsevier Ltd. All rights reserved.
The Equipment of Using AZOLLA for O2-Supplimentation and its Test

NASA Astrophysics Data System (ADS)

Liu, Xia-Shi; Chen, Min; Bian, Zu-Liang; Liu, Chung-Chu

The water-consuming amount in a long-term astro-navigation is large. In order to reduce the burden of water supply from Earth ground, the space station needs to resolve the problems of water supply. For this reason, the recovery and regeneration of urine solution of spacemen, and its utilization possess a key importance. Many investigations on this aspect have been reported. Our research based on "biological absorption-purification-UV photocatalytic oxidation" techniques with a relevant treating equipment that for a comprehensive treatment to fresh urine of spacemen has been created. In this equipment, the urine solution was used as the nutrient solution for the biological parts in ecological life ensurant system, after absorbing the nutrient, it was decomposed, metabolized and purified in some distance, and created a favorable condition for the follow-up oxidation treatment by UV-Photocatalytic Oxidation. After these two processes, the treated urine solution reached the GB5749-85 standard of water quality. Some main indexes are as table one. Chroma<5-15 Feculent degree-NTU-1.20-3 --5 Total rigidity-according to CaCO3-mg/L-3.60-450 N-NO3--mg/L-0.60-20 Soluble total solid-mg/L-543-1000 Bacterial gross-cfu/ml-13-100 Coliform group-No./L-<3-3 Key words-Photocatalytic Oxidation , Ultraviolet
Starch derivative-based superabsorbent with integration of water-retaining and controlled-release fertilizers.

PubMed

Zhong, Kang; Lin, Zuan-Tao; Zheng, Xi-Liang; Jiang, Gang-Biao; Fang, Yu-Sheng; Mao, Xiao-Yun; Liao, Zong-Wen

2013-02-15

Phosphate rock (PHR), a traditional fertilizer, is abundant, but is hard to be utilized by plants. To improve the utilization of PHR, and to integrate water-retaining and controlled-release fertilizers, an agricultural superabsorbent polymer based on sulfonated corn starch/poly (acrylic acid) embedding phosphate rock (SCS/PAA/PHR) was prepared. PHR can be suspended and well-dispersed in SCS/PAA by sulfonated corn starch (SCS). PHR and KOH were mixed in acrylic acid solution to provide phosphorus (P) and potassium (K) nutrients, respectively. Impacts on water absorption capacity of the superabsorbent were investigated. The maximum swelling capacity in distilled water or 0.9 wt.% (weight percent) NaCl solution reached 498 g g(-1) and 65 g g(-1) (water/prepared dry superabsorbent) respectively. Moreover, release behaviours of P and K in SCS/PAA/PHR were also investigated. The results showed that SCS/PAA/PHR possessed excellent sustained-release property of plant nutrient, and the SCS/PAA could improve the P release greatly. Besides, the XPS analysis was employed to study the relationship between PHR and superabsorbent polymer. Copyright © 2012 Elsevier Ltd. All rights reserved.
Method 365.5 Determination of Orthophosphate in Estuarine and Coastal Waters by Automated Colorimetric Analysis

EPA Science Inventory

This method provides a procedure for the determination of low-level orthophosphate concentrations normally found in estuarine and/or coastal waters. It is based upon the method of Murphy and Riley1 adapted for automated segmented flow analysis2 in which the two reagent solutions ...
TITANIUM DIOXIDE AND ULTRA-VIOLET LIGHT: A SUSTAINABLE AND INEXPENSIVE SOLUTION FOR ADDRESSING DRINKING WATER QUALITY ISSUES IN THE DEVELOPING COUNTRIES

EPA Science Inventory

The Ti0₂ based purification system reactor was built and tested by various diagnostic techniques for its efficacy in detoxification of water against organic and biological matter. Initial experiments were done with ultraviolet lamp as ...
Production of nanocrystalline metal powders via combustion reaction synthesis

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

Frye, John G.; Weil, Kenneth Scott; Lavender, Curt A.

Nanocrystalline metal powders comprising tungsten, molybdenum, rhenium and/or niobium can be synthesized using a combustion reaction. Methods for synthesizing the nanocrystalline metal powders are characterized by forming a combustion synthesis solution by dissolving in water an oxidizer, a fuel, and a base-soluble, ammonium precursor of tungsten, molybdenum, rhenium, or niobium in amounts that yield a stoichiometric burn when combusted. The combustion synthesis solution is then heated to a temperature sufficient to substantially remove water and to initiate a self-sustaining combustion reaction. The resulting powder can be subsequently reduced to metal form by heating in a reducing gas environment.
Competitive adsorption from mixed hen egg-white lysozyme/surfactant solutions at the air-water interface studied by tensiometry, ellipsometry, and surface dilational rheology.

PubMed

Alahverdjieva, V S; Grigoriev, D O; Fainerman, V B; Aksenenko, E V; Miller, R; Möhwald, H

2008-02-21

The competitive adsorption at the air-water interface from mixed adsorption layers of hen egg-white lysozyme with a non-ionic surfactant (C10DMPO) was studied and compared to the mixture with an ionic surfactant (SDS) using bubble and drop shape analysis tensiometry, ellipsometry, and surface dilational rheology. The set of equilibrium and kinetic data of the mixed solutions is described by a thermodynamic model developed recently. The theoretical description of the mixed system is based on the model parameters for the individual components.
DESTRUCTION OF PAHS AND PCBS IN WATER USING SULFATE RADICAL-BASED CATALYTIC ADVANCED OXIDATION PROCESSES

EPA Science Inventory

A new class of advanced oxidation processes (AOPs) based on sulfate radicals is being tested for the degradation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in aqueous solution. These AOPs are based on the generation of sulfate radicals through...
Adsorptive removal of Lead from water by the effective and reusable magnetic cellulose nanocomposite beads entrapping activated bentonite.

PubMed

Luo, Xiaogang; Lei, Xiaojuan; Xie, Xiuping; Yu, Bo; Cai, Ning; Yu, Faquan

2016-10-20

Many efforts have been driven to decontaminate the drinking water, and the development of efficient adsorbents with the advantages of cost-effectiveness and operating convenience for the removal of Pb(2+) from water is a major challenge. This work was aimed to explore the possibility of using cellulose-based adsorbents for efficient adsorption of Pb(2+). The millimeter-scale magnetic cellulose-based nanocomposite beads were fabricated via an optimal extrusion dropping technology by blending cellulose with the carboxyl-functionalized magnetite nanoparticles and acid-activated bentonite in NaOH/urea aqueous solution, and then they had been tested to evaluate the effectiveness in the removal of Pb(2+) from water. The effects of contact time, initial heavy metal ion concentrations, adsorption isotherms and solution pH on the sorption behavior were studied. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption processes were feasible, spontaneous, endothermic and mainly controlled by chemical mechanisms. The reusability of the adsorbent was also studied. Copyright © 2016 Elsevier Ltd. All rights reserved.
Detecting presence of live and dead pathogenic organisms in water and the water solutions by laser spectroscopy

NASA Astrophysics Data System (ADS)

Moguilnaya, T.; Suminov, I.; Ignatov, S.

2017-05-01

Presented is a new method for the recognition of live or dead pathogens in water. This method is based on the diagnostics of non-linear effects that comprise two phenomena: an induced luminescence of DNA under the influence of laser radiation, and a stimulated Brillouin scattering (SBS). The following model parameters were selected for the identification: the peak positions of spectral lines corresponding to pathogens and the difference between two wavelengths corresponding, respectively, to a laser mode maximum, and to a peak of the spectral line of a pathogen. A large volume of experimental data has been obtained and statistical analysis using Student’s test was carried out in order to determine the probability of the detection of spectra. The dynamics of the spectra of direct dispersion have been studied for a number of bacteria. Based on these results, the method and the device were developed. That device was tested in a water pipe line. In addition, we have studied the dynamics of changes in the spectra for solutions containing live bacteria and dead cells.
Motion-based, high-yielding, and fast separation of different charged organics in water.

PubMed

Xuan, Mingjun; Lin, Xiankun; Shao, Jingxin; Dai, Luru; He, Qiang

2015-01-12

We report a self-propelled Janus silica micromotor as a motion-based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self-propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s(-1) . Biotin-functionalized Janus micromotors can specifically capture and rapidly transport streptavidin-modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self-propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab-on-chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Highly selective luminescent sensing of picric acid based on a water-stable europium metal-organic framework

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

Xia, Tifeng; Zhu, Fengliang; Cui, Yuanjing, E-mail: cuiyj@zju.edu.cn

A water-stable metal-organic framework (MOF) EuNDC has been synthesized for selective detection of the well-known contaminant and toxicant picric acid (PA) in aqueous solution. Due to the photo-induced electron transfer and self-absorption mechanism, EuNDC displayed rapid, selective and sensitive detection of PA with a detection limit of 37.6 ppb. Recyclability experiments revealed that EuNDC retains its initial luminescent intensity and same quenching efficiency in each cycle, suggesting high photostability and reusability for long-term sensing applications. The excellent detection performance of EuNDC makes it a promising PA sensing material for practical applications. - Graphical abstract: A water-stable europium-based metal-organic framework hasmore » been reported for highly selective sensing of picric acid (PA) with a detection limit of 37.6 ppb in aqueous solution. - Highlights: • A water-stable metal-organic framework (MOF) EuNDC was synthesized. • The highly selective detection of picric acid with a detection limit of 37.6 ppb was realized. • The detection mechanism were also presented and discussed.« less
Near-infrared studies of glucose and sucrose in aqueous solutions: water displacement effect and red shift in water absorption from water-solute interaction.

PubMed

Jung, Youngeui; Hwang, Jungseek

2013-02-01

We used near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in aqueous solutions in the near-infrared range (3800-7500 cm(-1)). Here we introduce a new method to obtain reliable glucose absorption bands from aqueous glucose solutions without measuring the water displacement coefficients of glucose separately. Additionally, we were able to extract the water displacement coefficients of glucose, and this may offer a new general method using spectroscopy techniques applicable to other water-soluble materials. We also observed red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from the contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift gets larger as the concentration increases, which indicates that as the concentration increases more water molecules are involved in the interaction. However, the red shift in frequency does not seem to depend significantly on the concentration. We also performed the same measurements and analysis with sucrose instead of glucose as solute and compared.
Experimentally induced hyperchloremic and DL-lactic acidosis in calves: an attempt to study the effects of oral rehydration on acid-base status.

PubMed

Schwedhelm, L; Kirchner, D; Klaus, B; Bachmann, L

2013-04-01

Many diarrheic calves suffer from metabolic acidosis, which is commonly treated by oral rehydration therapy. Oral rehydration solutions can be prepared in water, milk, or milk replacer. Therefore, the aim of the study was to verify dietary effects of water- or milk replacer-based oral rehydration solutions on parameters of acid-base balance in calves with experimentally induced hyperchloremic and dl-lactate acidosis. In 12 calves, hyperchloremic or dl-lactate acidosis was induced by HCl or dl-lactic acid infusions according to protocols outlined in previous literature. Immediately after induction, the calves were fed with milk replacer or water- or milk replacer-based oral rehydration solutions, or remained fasting, respectively. Blood samples were taken to monitor acid-base status over an experimental period of 4h. Using the protocols, all calves revealed a manifest hyperchloremic or dl-lactate acidosis. Because of high infusion volumes, plasma volume was expanded and effects of feeding regimens on blood parameters were rare. Unexpected clinical aberrations occurred after repeated induction of dl-lactate acidosis: all calves developed a thrombophlebitis of the jugular vein, whereas HCl infusion had no effect on endothelium. Induction of acidosis via infusion is not suitable to study dietary effects. A protocol to induce acidosis and dehydration simultaneously is required to duplicate the metabolic conditions of diarrheic calves. In further investigations, attention should be focused on effects of d-lactate or its metabolites on endothelial tissue. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Kinetics and equilibrium of solute diffusion into human hair.

PubMed

Wang, Liming; Chen, Longjian; Han, Lujia; Lian, Guoping

2012-12-01

The uptake kinetics of five molecules by hair has been measured and the effects of pH and physical chemical properties of molecules were investigated. A theoretical model is proposed to analyze the experimental data. The results indicate that the binding affinity of solute to hair, as characterized by hair-water partition coefficient, scales to the hydrophobicity of the solute and decreases dramatically as the pH increases to the dissociation constant. The effective diffusion coefficient of solute depended not only on the molecular size as most previous studies suggested, but also on the binding affinity as well as solute dissociation. It appears that the uptake of molecules by hair is due to both hydrophobic interaction and ionic charge interaction. Based on theoretical considerations of the cellular structure, composition and physical chemical properties of hair, quantitative-structure-property-relationships (QSPR) have been proposed to predict the hair-water partition coefficient (PC) and the effective diffusion coefficient (D (e)) of solute. The proposed QSPR models fit well with the experimental data. This paper could be taken as a reference for investigating the adsorption properties for polymeric materials, fibres, and biomaterials.
Installation Assessment of Frankford Arsenal.

DTIC Science & Technology

1977-10-01

sulfate , sulfuric acid , ac ’solution 40 Hot water bath 41 Nickel plate Nickel sulfate and chloride sulfuric acid , acid ...solution 42 Chromium Copper plate Copper sulfate and sulfuric acid , acid solution 11-14 TABLE 11-2 (continued) Tank No. Plating Process Use Contents...46 Water rinse Water 47 Water rinse Water 48 Water rinse Water 49 Acid Chromic acid , acetic acid , nickel sulfate and sulfuric

Blepharitis

MedlinePlus

... base of the eyelashes as well. Causes The exact cause of blepharitis is unknown. It is thought ... day. After the warm compresses, gently rub a solution of warm water and no-tears baby shampoo ...
In-line bulk supersaturation measurement by electrical conductometry in KDP crystal growth from aqueous solution

NASA Astrophysics Data System (ADS)

Bordui, P. F.; Loiacono, G. M.

1984-07-01

A method is presented for in-line bulk supersaturation measurement in crystal growth from aqueous solution. The method is based on a computer-controlled concentration measurement exploiting an experimentally predetermined cross-correlation between the concentration, electrical conductivity, and temperature of the growth solution. The method was applied to Holden crystallization of potassium dihydrogen phosphate (KDP). An extensive conductivity-temperature-concentration data base was generated for this system over a temperature range of 31 to 41°C. The method yielded continous, automated bulk supersaturation output accurate to within ±0.05 g KDP100 g water (±0.15% relative supersaturation).
Facile synthesis of stable superhydrophobic nanocomposite based on multi-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Mokarian, Zahra; Rasuli, Reza; Abedini, Yousefali

2016-04-01

A facile approach to fabricate a stable superhydrophobic composite comprising multi-walled carbon nanotubes and silicone rubber has been reported. Contact angle of de-ionized water droplets on the prepared surface was measured with the value of near 159°; while water droplets easily rolled off and bounced on it. Surface free energy of the superhydrophobic coating was examined by three methods about 26 mJ/m2. The prepared film shows good stability under high stress conditions such as ultraviolet exposure, heating, pencil hardness test, attacking with different pH value and ionic-strength solutions. In addition, remarkable stability of the coating was observed after soaking in condensed hydrochloric acid, 5 wt.% NaCl aqueous solution, boiling water and tape test.
Report on Non-invasive acoustic monitoring of D2O concentration Oct 31 2017

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

Pantea, Cristian; Sinha, Dipen N.; Lakis, Rollin Evan

There is an urgent need for real-time monitoring of the hydrogen /deuterium ratio (H/D) for heavy water production monitoring. Based upon published literature, sound speed is sensitive to the deuterium content of heavy water and can be measured using existing acoustic methods to determine the deuterium concentration in heavy water solutions. We plan to adapt existing non-invasive acoustic techniques (Swept-Frequency Acoustic Interferometry and Gaussian-pulse acoustic technique) for the purpose of quantifying H/D ratios in solution. A successful demonstration will provide an easily implemented, low cost, and non-invasive method for remote and unattended H/D ratio measurements with a resolution of lessmore » than 0.2% vol.« less
Solute deposition from cloud water to the canopy of a puerto rican montane forest

NASA Astrophysics Data System (ADS)

Asbury, Clyde E.; McDowell, William H.; Trinidad-Pizarro, Roberto; Berrios, Samuel

Deposition of cloud water and dissolved solutes onto vegetation was studied by sampling clouds, throughfall and stemflow during 12 cloud-only events at Pico Del Este, a tropical cloud forest in the Luquillo Mountains of Puerto Rico. Liquid water content of the sampled clouds was low (0.016 g m -3), but deposition of water (1.3 mm d -1)was comparable to other sites, apparently due to efficient capture of clouds by epiphyte-laden vegetation. Elemental deposition by cloud water was similar to that in other, more polluted sites, but was only 8-30% of total deposition (cloud-only plus rain) due to the high rainfall at the site (approximately 5 m). Na and CI from marine aerosols dominated cloud chemistry, with concentrations of 400 μeqδ -1. Sulfate and nitrate concentrations were 180 and 60 μedδ -1, respectively. After passage through the canopy, concentrations of base cations in deposited cloud water increased, and concentrations of nitrogen decreased.
Tunable Physical Properties of Ethylcellulose/Gelatin Composite Nanofibers by Electrospinning.

PubMed

Liu, Yuyu; Deng, Lingli; Zhang, Cen; Feng, Fengqin; Zhang, Hui

2018-02-28

In this work, the ethylcellulose/gelatin blends at various weight ratios in water/ethanol/acetic acid solution were electrospun to fabricate nanofibers with tunable physical properties. The solution compatibility was predicted based on Hansen solubility parameters and evaluated by rheological measurements. The physical properties were characterized by scanning electron microscopy, porosity, differential scanning calorimetry, thermogravimetry, Fourier transform infrared spectroscopy, and water contact angle. Results showed that the entangled structures among ethylcellulose and gelatin chains through hydrogen bonds gave rise to a fine morphology of the composite fibers with improved thermal stability. The fibers with higher gelatin ratio (75%), possessed hydrophilic surface (water contact angle of 53.5°), and adequate water uptake ability (1234.14%), while the fibers with higher ethylcellulose proportion (75%) tended to be highly water stable with a hydrophobic surface (water contact angle of 129.7°). This work suggested that the composite ethylcellulose/gelatin nanofibers with tunable physical properties have potentials as materials for bioactive encapsulation, food packaging, and filtration applications.
The thermochemical characteristics of solution of phenol and benzoic acid in water-dimethylsulfoxide and water-acetonitrile mixtures

NASA Astrophysics Data System (ADS)

Zakharov, A. G.; Voronova, M. I.; Batov, D. V.; Smirnova, K. V.

2011-03-01

The solution of phenol and benzoic acid in water-dimethylsulfoxide (DMSO) and water-acetonitrile (AN) mixtures was studied. As distinct from benzoic acid, the thermodynamic characteristics of solution of phenol sharply change at concentrations corresponding to a change in the character of cluster formation in water-DMSO and water-AN mixtures. Differences in the solvation of phenol and benzoic acid are explained by different mechanisms of the interaction of the solutes with clusters existing in binary mixtures.
Membrane-based osmotic heat engine with organic solvent for enhanced power generation from low-grade heat.

PubMed

Shaulsky, Evyatar; Boo, Chanhee; Lin, Shihong; Elimelech, Menachem

2015-05-05

We present a hybrid osmotic heat engine (OHE) system that uses draw solutions with an organic solvent for enhanced thermal separation efficiency. The hybrid OHE system produces sustainable energy by combining pressure-retarded osmosis (PRO) as a power generation stage and membrane distillation (MD) utilizing low-grade heat as a separation stage. While previous OHE systems employed aqueous electrolyte draw solutions, using methanol as a solvent is advantageous because methanol is highly volatile and has a lower heat capacity and enthalpy of vaporization than water. Hence, the thermal separation efficiency of a draw solution with methanol would be higher than that of an aqueous draw solution. In this study, we evaluated the performance of LiCl-methanol as a potential draw solution for a PRO-MD hybrid OHE system. The membrane transport properties as well as performance with LiCl-methanol draw solution were evaluated using thin-film composite (TFC) PRO membranes and compared to the results obtained with a LiCl-water draw solution. Experimental PRO methanol flux and maximum projected power density of 47.1 L m(-2) h(-1) and 72.1 W m(-2), respectively, were achieved with a 3 M LiCl-methanol draw solution. The overall efficiency of the hybrid OHE system was modeled by coupling the mass and energy flows between the thermal separation (MD) and power generation (PRO) stages under conditions with and without heat recovery. The modeling results demonstrate higher OHE energy efficiency with the LiCl-methanol draw solution compared to that with the LiCl-water draw solution under practical operating conditions (i.e., heat recovery<90%). We discuss the implications of the results for converting low-grade heat to power.
Membrane-Based Osmotic Heat Engine with Organic Solvent for Enhanced Power Generation from Low-Grade Heat

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

Shaulsky, E; Boo, C; Lin, SH

We present a hybrid osmotic heat engine (OHE) system that uses draw solutions with an organic solvent for enhanced thermal separation efficiency. The hybrid OHE system produces sustainable energy by combining pressure-retarded osmosis (PRO) as a power generation stage and membrane distillation (MD) utilizing low-grade heat as a separation stage. While previous OHE systems employed aqueous electrolyte draw solutions, using methanol as a solvent is advantageous because methanol is highly volatile and has a lower heat capacity and enthalpy of vaporization than water. Hence, the thermal separation efficiency of a draw solution with methanol would be higher than that ofmore » an aqueous draw solution. In this study, we evaluated the performance of LiCl-methanol as a potential draw solution for a PRO-MD hybrid OHE system. The membrane transport properties as well as performance with LiCl methanol draw solution were evaluated using thin-film composite (TFC) PRO membranes and compared to the results obtained with a LiCl water draw solution. Experimental PRO methanol flux and maximum projected power density of 47.1 L m(-2) h(-1) and 72.1 W m(-2), respectively, were achieved with a 3 M LiCl-methanol draw solution. The overall efficiency of the hybrid OHE system was modeled by coupling the mass and energy flows between the thermal separation (MD) and power generation (PRO) stages under conditions with and without heat recovery. The modeling results demonstrate higher ORE energy efficiency with the LiCl methanol draw solution compared to that with the LiCl water draw solution under practical operating conditions (i.e., heat recovery <90%). We discuss the implications of the results for converting low-grade heat to power.« less
Effects of radiation damping for biomolecular NMR experiments in solution: a hemisphere concept for water suppression

PubMed Central

Ishima, Rieko

2016-01-01

Abundant solvent nuclear spins, such as water protons in aqueous solution, cause radiation damping in NMR experiments. It is important to know how the effect of radiation damping appears in high-resolution protein NMR because macromolecular studies always require very high magnetic field strengths with a highly sensitive NMR probe that can easily cause radiation damping. Here, we show the behavior of water magnetization after a pulsed-field gradient (PFG) using nutation experiments at 900 MHz with a cryogenic probe: when water magnetization is located in the upper hemisphere (having +Z component, parallel to the external magnetic field), dephasing of the magnetization by a PFG effectively suppresses residual water magnetization in the transverse plane. In contrast, when magnetization is located in the lower hemisphere (having −Z component), the small residual transverse component remaining after a PFG is still sufficient to induce radiation damping. Based on this observation, we designed 1H-15N HSQC experiments in which water magnetization is maintained in the upper hemisphere, but not necessarily along Z, and compared them with the conventional experiments, in which water magnetization is inverted during the t1 period. The result demonstrates moderate gain of signal-to-noise ratio, 0–28%. Designing the experiments such that water magnetization is maintained in the upper hemisphere allows shorter pulses to be used compared to the complete water flip-back and, thereby, is useful as a building block of protein NMR pulse programs in solution. PMID:27524944
[Effects of tree species transfer on soil dissolved organic matter pools in a reforested Chinese fir (Cunninghamia lanceolata) woodland].

PubMed

Wan, Xiao-Hua; Huang, Zhi-Qun; He, Zong-Ming; Hu, Zhen-Hong; Yu, Zai-Peng; Wang, Min-Huang; Yang, Yu-Sheng; Fan, Shao-Hui

2014-01-01

Based on the comparison between reforested 19-year-old Mytilaria laosensis and Cunninghamia lanceolata plantations on cut-over land of C. lanceolata, effects of tree species transfer on soil dissolved organic matter were investigated. Cold water, hot water and 2 mol x L(-1) KCl solution were used to extract soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) from 0-5, 5-10 and 10-20 cm soil layers. In M. laosensis plantaion, the concentrations of soil DOC extracted by cold water, hot water and 2 mol L(-1) KCl solutions were significantly higher than that in C. lanceolata plantation. In the 0-5 and 5-10 cm layers, the concentrations of soil DON extracted by cold water and hot water in M. laosensis plantation were significantly higher than that in C. lanceolata plantation. The extracted efficiencies for DOC and DON were both in order of KCl solution > hot water > cold water. In the 0-5 cm layers, soil microbial biomass carbon (MBC) under M. laosensis was averagely 76.3% greater than under C. lanceolata. Correlation analysis showed that there were significant positive relationships between hot water extractable organic matter and soil MBC. Differences in the sizes of soil DOC and DON pools between the M. laosensis and C. lanceolata forests might be attributed to the quality and quantity of organic matter input. The transfer from C. lanceolata to M. laosensis could improve soil fertility in the plantation.
Effect of cations on the solubilization/deposition of triclosan in sediment-water-rhamnolipid system.

PubMed

Chen, Yuanbo; Hu, Yongyou; Guo, Qian; Yan, Jia; Wu, Wenjin

2016-09-01

Cations had great influence on the self-assembly of rhamnolipid, which in turn affected the fate of triclosan. The migration of triclosan from sediment to water benefited its biodegradation but it could be transformed into more toxic compounds. To regulate the fate of triclosan and reduce environmental risks extremely, the effect of four common cations in surface water (Na(+)/K(+)/Ca(2+)/Mg(2+)) on the solubilization/deposition of triclosan in sediment-water-rhamnolipid system was investigated. The interaction among cations, triclosan and rhamnolipid was explored based on self-assembly of rhamnolipid and water solubility of triclosan in rhamnolipid solutions. Results showed that cations had little influence on the fate of triclosan in the absence of rhamnolipid. Cations, especially Ca(2+)/Mg(2+), reduced the critical micelle concentration, micellar size and zeta potential of rhamnolipid solutions. The changes in self-assembly of rhamnolipid with different cations led to the difference of residual rhamnolipid concentration in water, which was nearly invariant with 0.01 M Na(+)/K(+) while decreased significantly with 0.01 M Ca(2+)/Mg(2+). Consequently, water solubility of triclosan in rhamnolipid solutions increased with the addition of Na(+)/K(+) whereas decreased with Ca(2+)/Mg(2+). In sediment-water- rhamnolipid system, triclosan was slightly solubilized from sediment to water with Na(+)/K(+) while deposited in sediment with Ca(2+)/Mg(2+). These findings provided an alternative application of rhamnolipid for the remediation of triclosan-polluted sediment. Copyright © 2016. Published by Elsevier Ltd.
Fluoride-selective optical sensor based on the dipyrrolyl-tetrathiafulvalene chromophore.

PubMed

Rivadehi, Shadi; Reid, Ellen F; Hogan, Conor F; Bhosale, Sheshanath V; Langford, Steven J

2012-01-28

A chemosensor bearing dipyrrolyl motifs as recognition sites and a tetrathiafulvalene redox tag has been evaluated as an optical and redox sensor for a series of anions (F(-), Cl(-), Br(-), HSO(4)(-), CH(3)COO(-), and H(2)PO(4)(-)) in DCM solution. The receptor shows specific optical signaling for fluoride but little electrochemical effect in solution. The solid-state performance of the sensor leads to measurable changes in water. Design implications towards better systems based on these results and other examples are discussed.
Recycling of CdTe photovoltaic waste

DOEpatents

Goozner, Robert E.; Long, Mark O.; Drinkard, Jr., William F.

1999-04-27

A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base.
Recycling of CdTe photovoltaic waste

DOEpatents

Goozner, R.E.; Long, M.O.; Drinkard, W.F. Jr.

1999-04-27

A method for extracting and reclaiming metals from scrap CdTe photovoltaic cells and manufacturing waste by leaching the metals in dilute nitric acid, leaching the waste with a leaching solution comprising nitric acid and water, skimming any plastic material from the top of the leaching solution, separating the glass substrate from the liquid leachate, adding a calcium containing base to the leachate to precipitate Cd and Te, separating the precipitated Cd and Te from the leachate, and recovering the calcium-containing base. 3 figs.
Effect of spatial restriction on the photoluminescent properties of carbon nanomaterials

NASA Astrophysics Data System (ADS)

Vostrikova, A. M.; Nikolaeva, A. N.; Bakal, A. A.; Shpuntova, D. V.; Mordovina, E. A.; Sukhorukov, G. B.; Sapelkin, A. V.; Goryacheva, I. Yu.

2018-04-01

Photoluminescent (PL) properties of carbon-based nanomaterials obtained on the base of sodium dextran sulfate (DS) were compared. DS water solution, dry powder and co-precipitated inside pores of CaCO3 microparticles solution were thermally treated and clear difference between these materials was found. Effect of spatial restriction of CaCO3 pores showed itself in the identity of PL properties for material, obtained by thermal and hydrothermal treatment; in the absence of CaCO3 microparticles the PL spectra were quite different.
Optimized MBR for greywater reuse systems in hotel facilities.

PubMed

Atanasova, Natasa; Dalmau, Montserrat; Comas, Joaquim; Poch, Manel; Rodriguez-Roda, Ignasi; Buttiglieri, Gianluigi

2017-05-15

Greywater is an important alternative water source, particularly in semi-arid, touristic areas, where the biggest water demand is usually in the dry period. By using this source wisely, tourist facilities can substantially reduce the pressure to scarce water resources. In densely urbanized touristic areas, where space has high value, compact solutions such as MBR based greywater reuse systems appear very appropriate. This research focuses on technical and economical evaluation of such solution by implementing a pilot MBR to a hotel with separated grey water. The pilot was operated for 6 months, with thorough characterisation of the GW performed, its operation was monitored and its energy consumption was optimized by applying a control system for the air scour. Based on the pilot operation a design and economic model was set to estimate the feasibility (CAPEX, OPEX, payback period of investment) of appropriate scales of MBR based GW systems, including separation of GW, MBR technology, clean water storage and disinfection. The model takes into account water and energy prices in Spain and a planning period of 20 years. The results demonstrated an excellent performance in terms of effluent quality, while the energy demand for air-scour was reduced by up to 35.2%, compared to the manufacturer recommendations. Economical evaluation of the entire MBR based GW reuse system shows its feasibility for sizes already at 5 m 3 /day (60 PE). The payback period of the investment for hotels like the demonstration hotel, treating 30 m 3 /day is 3 years. Copyright © 2017 Elsevier Ltd. All rights reserved.
Water system microbial check valve development

NASA Technical Reports Server (NTRS)

Colombo, G. V.; Greenley, D. R.; Putnam, D. F.

1978-01-01

A residual iodine microbial check valve (RIMCV) assembly was developed and tested. The assembly is designed to be used in the space shuttle potable water system. The RIMCV is based on an anion exchange resin that is supersaturated with an iodine solution. This system causes a residual to be present in the effluent water which provides continuing bactericidal action. A flight prototype design was finalized and five units were manufactured and delivered.
Aqueous route to facile, efficient and functional silica coating of metal nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Shah, Kwok Wei; Sreethawong, Thammanoon; Liu, Shu-Hua; Zhang, Shuang-Yuan; Tan, Li Sirh; Han, Ming-Yong

2014-09-01

Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields.Various metal (Ag, Au, and Pt)@thiol-functionalized silica (SiO2-SH) nanoparticles (NPs) are successfully prepared at room temperature by a facile, efficient, functional, universal and scalable coating process in alcohol-free aqueous solution using pre-hydrolyzed 3-(mercaptopropyl)trimethoxysilane (MPTMS). The controlled pre-hydrolysis of the silane precursor in water and the consecutive condensation processes are the key to achieve the effective and uniform silica coating on metal NPs in aqueous solution. The thickness of the silica shell is tuned by simply varying the coating time. The silica shell can act as an effective protecting layer for Ag NPs in Ag@SiO2-SH NPs under conditions for silica coating in aqueous solution; however, it leads to a directional dissolution of Ag NPs in a more strongly basic ammonia solution. The environmentally friendly silica coating process in water is also applied to prepare highly surface-enhanced Raman scattering (SERS)-active Ag@SiO2-SH NPs with different types of Raman molecules for highly sensitive SERS-based applications in various fields. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03306j
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.

TH-CD-202-05: DECT Based Tissue Segmentation as Input to Monte Carlo Simulations for Proton Treatment Verification Using PET Imaging

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

Berndt, B; Wuerl, M; Dedes, G

Purpose: To improve agreement of predicted and measured positron emitter yields in patients, after proton irradiation for PET-based treatment verification, using a novel dual energy CT (DECT) tissue segmentation approach, overcoming known deficiencies from single energy CT (SECT). Methods: DECT head scans of 5 trauma patients were segmented and compared to existing decomposition methods with a first focus on the brain. For validation purposes, three brain equivalent solutions [water, white matter (WM) and grey matter (GM) – equivalent with respect to their reference carbon and oxygen contents and CT numbers at 90kVp and 150kVp] were prepared from water, ethanol, sucrosemore » and salt. The activities of all brain solutions, measured during a PET scan after uniform proton irradiation, were compared to Monte Carlo simulations. Simulation inputs were various solution compositions obtained from different segmentation approaches from DECT, SECT scans, and known reference composition. Virtual GM solution salt concentration corrections were applied based on DECT measurements of solutions with varying salt concentration. Results: The novel tissue segmentation showed qualitative improvements in %C for patient brain scans (ground truth unavailable). The activity simulations based on reference solution compositions agree with the measurement within 3–5% (4–8Bq/ml). These reference simulations showed an absolute activity difference between WM (20%C) and GM (10%C) to H2O (0%C) of 43 Bq/ml and 22 Bq/ml, respectively. Activity differences between reference simulations and segmented ones varied from −6 to 1 Bq/ml for DECT and −79 to 8 Bq/ml for SECT. Conclusion: Compared to the conventionally used SECT segmentation, the DECT based segmentation indicates a qualitative and quantitative improvement. In controlled solutions, a MC input based on DECT segmentation leads to better agreement with the reference. Future work will address the anticipated improvement of quantification accuracy in patients, comparing different tissue decomposition methods with an MR brain segmentation. Acknowledgement: DFG-MAP and HIT-Heidelberg Deutsche Forschungsgemeinschaft (MAP); Bundesministerium fur Bildung und Forschung (01IB13001)« less
Highly permeable polymeric membranes based on the incorporation of the functional water channel protein Aquaporin Z

PubMed Central

Kumar, Manish; Grzelakowski, Mariusz; Zilles, Julie; Clark, Mark; Meier, Wolfgang

2007-01-01

The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA15-PDMS110-PMOXA15) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to ≈800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (Ea) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications. PMID:18077364
Detoxification of Chemical Warfare Agents Using a Zr6 -Based Metal-Organic Framework/Polymer Mixture.

PubMed

Moon, Su-Young; Proussaloglou, Emmanuel; Peterson, Gregory W; DeCoste, Jared B; Hall, Morgan G; Howarth, Ashlee J; Hupp, Joseph T; Farha, Omar K

2016-10-10

Owing to their high surface area, periodic distribution of metal sites, and water stability, zirconium-based metal-organic frameworks (Zr 6 -MOFs) have shown promising activity for the hydrolysis of nerve agents GD and VX, as well as the simulant, dimethyl 4-nitrophenylphosphate (DMNP), in buffered solutions. A hurdle to using MOFs for this application is the current need for a buffer solution. Here the destruction of the simulant DMNP, as well as the chemical warfare agents (GD and VX) through hydrolysis using a MOF catalyst mixed with a non-volatile, water-insoluble, heterogeneous buffer is reported. The hydrolysis of the simulant and nerve agents in the presence of the heterogeneous buffer was fast and effective. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Thermodynamic Studies of Levitated Microdroplets of Highly Supersaturated Electrolyte Solutions

NASA Technical Reports Server (NTRS)

Myerson, Allan S.; Izmailov, Alexander F.; Na, Han-Soo

1996-01-01

Highly supersaturated electrolyte solutions are studied by employing an electrodynamic levitator trap (ELT) technique. The ELT technique involves containerless suspension of a microdroplet thus eliminating dust, dirt, and container walls which normally cause heterogeneous nucleation. This allows very high supersaturations to be achieved. A theoretical study of the experimental results obtained for the water activity in microdroplets of various electrolyte solutions is based on the development of the Cahn-Hilliard formalism for electrolyte solutions. A correspondence of 96-99% between the theory and experiment for the all solutions studied was achieved and allowed the determination of an analytical expression for the spinodal concentration n(sub spin) and its calculation for various electrolyte solutions at 298 K.
Implementation of Solute Transport in the Vadose Zone into the `HYDRUS Package for MODFLOW'

NASA Astrophysics Data System (ADS)

Simunek, J.; Beegum, S.; Szymkiewicz, A.; Sudheer, K. P.

2017-12-01

The 'HYDRUS package for MODFLOW' was developed by Seo et al. (2007) and Twarakavi et al. (2008) to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package, which is based on the HYDRUS-1D model (Šimůnek et al., 2016) simulating unsaturated water flow in the vadose zone, was incorporated into MODFLOW (Harbaugh et al., 2000) simulating saturated groundwater flow. The HYDRUS package in the coupled model can be used to represent the effects of various unsaturated zone processes, including infiltration, evaporation, root water uptake, capillary rise, and recharge in homogeneous or layered soil profiles. The coupled model is effective in addressing spatially-variable saturated-unsaturated hydrological processes at the regional scale, allowing for complex layering in the unsaturated zone, spatially and temporarily variable water fluxes at the soil surface and in the root zone, and with alternating recharge and discharge fluxes (Twarakavi et al., 2008). One of the major limitations of the coupled model was that it could not be used to simulate at the same time solute transport. However, solute transport is highly dependent on water table fluctuations due to temporal and spatial variations in groundwater recharge. This is an important concern when the coupled model is used for analyzing groundwater contamination due to transport through the unsaturated zone. The objective of this study is to integrate the solute transport model (the solute transport part of HYDRUS-1D for the unsaturated zone and MT3DMS (Zheng and Wang, 1999; Zheng, 2009) for the saturated zone) into an existing coupled water flow model. The unsaturated zone component of the coupled model can consider solute transport involving many biogeochemical processes and reactions, including first-order degradation, volatilization, linear or nonlinear sorption, one-site kinetic sorption, two-site sorption, and two-kinetic sites sorption (Šimůnek and van Genuchten, 2008). Due to complex interactions at the groundwater table, certain modifications of the pressure head (compared to the original coupling) and solute concentration profiles were incorporated into the HYDRUS package. The developed integrated model is verified using HYDRUS-2D and analyzed for its computational time requirements.
Potential of mean force between two hydrophobic solutes in water.

PubMed

Southall, Noel T; Dill, Ken A

2002-12-10

We study the potential of mean force between two nonpolar solutes in the Mercedes Benz model of water. Using NPT Monte Carlo simulations, we find that the solute size determines the relative preference of two solute molecules to come into contact ('contact minimum') or to be separated by a single layer of water ('solvent-separated minimum'). Larger solutes more strongly prefer the contacting state, while smaller solutes have more tendency to become solvent-separated, particularly in cold water. The thermal driving forces oscillate with solute separation. Contacts are stabilized by entropy, whereas solvent-separated solute pairing is stabilized by enthalpy. The free energy of interaction for small solutes is well-approximated by scaled-particle theory. Copyright 2002 Elsevier Science B.V.
A Mathematical Model of Solute Coupled Water Transport in Toad Intestine Incorporating Recirculation of the Actively Transported Solute

PubMed Central

Larsen, Erik Hviid; Sørensen, Jakob Balslev; Sørensen, Jens Nørkær

2000-01-01

A mathematical model of an absorbing leaky epithelium is developed for analysis of solute coupled water transport. The non-charged driving solute diffuses into cells and is pumped from cells into the lateral intercellular space (lis). All membranes contain water channels with the solute passing those of tight junction and interspace basement membrane by convection-diffusion. With solute permeability of paracellular pathway large relative to paracellular water flow, the paracellular flux ratio of the solute (influx/outflux) is small (2–4) in agreement with experiments. The virtual solute concentration of fluid emerging from lis is then significantly larger than the concentration in lis. Thus, in absence of external driving forces the model generates isotonic transport provided a component of the solute flux emerging downstream lis is taken up by cells through the serosal membrane and pumped back into lis, i.e., the solute would have to be recirculated. With input variables from toad intestine (Nedergaard, S., E.H. Larsen, and H.H. Ussing, J. Membr. Biol. 168:241–251), computations predict that 60–80% of the pumped flux stems from serosal bath in agreement with the experimental estimate of the recirculation flux. Robust solutions are obtained with realistic concentrations and pressures of lis, and with the following features. Rate of fluid absorption is governed by the solute permeability of mucosal membrane. Maximum fluid flow is governed by density of pumps on lis-membranes. Energetic efficiency increases with hydraulic conductance of the pathway carrying water from mucosal solution into lis. Uphill water transport is accomplished, but with high hydraulic conductance of cell membranes strength of transport is obscured by water flow through cells. Anomalous solvent drag occurs when back flux of water through cells exceeds inward water flux between cells. Molecules moving along the paracellular pathway are driven by a translateral flow of water, i.e., the model generates pseudo-solvent drag. The associated flux-ratio equation is derived. PMID:10919860
Increase in Ice Nucleation Efficiency of Feldspars, Kaolinite and Mica in Dilute NH3 and NH4+-containing Solutions

NASA Astrophysics Data System (ADS)

Kumar, A.; Marcolli, C.; Luo, B.; Krieger, U. K.; Peter, T.

2017-12-01

Semivolatile species present in the atmosphere are prone to adhere to mineral dust particle surfaces during long range transport, and could potentially change the particle surface properties and its ice nucleation (IN) efficiency. Immersion freezing experiments were performed with microcline (K-feldspar), known to be highly IN active, suspended in aqueous solutions of ammonia, (NH4)2SO4, NH4HSO4, NH4NO3, NH4Cl, Na2SO4, H2SO4, K2SO4 and KCl to investigate the effect of solutes on the IN efficiency. Freezing of emulsified droplets investigated with a differential scanning calorimeter (DSC) showed that the heterogeneous ice nucleation temperatures deviate from the water activity-based IN theory, describing heterogeneous ice nucleation temperatures as a function of solution water activity by a constant offset with respect to the ice melting point curve (Zobrist et al. 2008). IN temperatures enhanced up to 4.5 K were observed for very dilute NH3 and NH4+-containing solutions while a decrease was observed as the concentration was further increased. For all solutes with cations other than NH4+, the IN efficiency decreased. An increase of the IN efficiency in very dilute NH3 and NH4+-containing solutions followed by a decrease with increasing concentration was also observed for sanidine (K-feldspar) and andesine (Na/Ca-feldspar). This is an important indication towards specific chemical interactions between solutes and the feldspar surface which is not captured by the water activity-based IN theory. A similar trend is present but less pronounced in case of kaolinite and mica, while quartz is barely affected. We hypothesize that the hydrogen bonding of NH3 molecules with surface -OH groups could be the reason for the enhanced freezing temperatures in dilute ammonia and ammonium containing solutions as they could form an ice-like overlayer providing hydrogen bonding groups for ice to nucleate on top of it. This implies to possibilities of enhanced IN efficiency, especially in mixed-phase cloud regime, of ammonium sulfate coated mineral dust particles in the condensation mode when the coating dilutes during cloud droplet activation.
Terrestrial Water Storage in African Hydrological Regimes Derived from GRACE Mission Data: Intercomparison of Spherical Harmonics, Mass Concentration, and Scalar Slepian Methods.

PubMed

Rateb, Ashraf; Kuo, Chung-Yen; Imani, Moslem; Tseng, Kuo-Hsin; Lan, Wen-Hau; Ching, Kuo-En; Tseng, Tzu-Pang

2017-03-10

Spherical harmonics (SH) and mascon solutions are the two most common types of solutions for Gravity Recovery and Climate Experiment (GRACE) mass flux observations. However, SH signals are degraded by measurement and leakage errors. Mascon solutions (the Jet Propulsion Laboratory (JPL) release, herein) exhibit weakened signals at submascon resolutions. Both solutions require a scale factor examined by the CLM4.0 model to obtain the actual water storage signal. The Slepian localization method can avoid the SH leakage errors when applied to the basin scale. In this study, we estimate SH errors and scale factors for African hydrological regimes. Then, terrestrial water storage (TWS) in Africa is determined based on Slepian localization and compared with JPL-mascon and SH solutions. The three TWS estimates show good agreement for the TWS of large-sized and humid regimes but present discrepancies for the TWS of medium and small-sized regimes. Slepian localization is an effective method for deriving the TWS of arid zones. The TWS behavior in African regimes and its spatiotemporal variations are then examined. The negative TWS trends in the lower Nile and Sahara at -1.08 and -6.92 Gt/year, respectively, are higher than those previously reported.
In situ generation of hydrogen from water by aluminum corrosion in solutions of sodium aluminate

NASA Astrophysics Data System (ADS)

Soler, Lluís; Candela, Angélica María; Macanás, Jorge; Muñoz, Maria; Casado, Juan

A new process to obtain hydrogen from water using aluminum in sodium aluminate solutions is described and compared with results obtained in aqueous sodium hydroxide. This process consumes only water and aluminum, which are raw materials much cheaper than other compounds used for in situ hydrogen generation, such as hydrocarbons and chemical hydrides, respectively. As a consequence, our process could be an economically feasible alternative for hydrogen to supply fuel cells. Results showed an improvement of the maximum rates and yields of hydrogen production when NaAlO 2 was used instead of NaOH in aqueous solutions. Yields of 100% have been reached using NaAlO 2 concentrations higher than 0.65 M and first order kinetics at concentrations below 0.75 M has been confirmed. Two different heterogeneous kinetic models are verified for NaAlO 2 aqueous solutions. The activation energy (E a) of the process with NaAlO 2 is 71 kJ mol -1, confirming a control by a chemical step. A mechanism unifying the behavior of Al corrosion in NaOH and NaAlO 2 solutions is presented. The application of this process could reduce costs in power sources based on fuel cells that nowadays use hydrides as raw material for hydrogen production.
Terrestrial Water Storage in African Hydrological Regimes Derived from GRACE Mission Data: Intercomparison of Spherical Harmonics, Mass Concentration, and Scalar Slepian Methods

PubMed Central

Rateb, Ashraf; Kuo, Chung-Yen; Imani, Moslem; Tseng, Kuo-Hsin; Lan, Wen-Hau; Ching, Kuo-En; Tseng, Tzu-Pang

2017-01-01

Spherical harmonics (SH) and mascon solutions are the two most common types of solutions for Gravity Recovery and Climate Experiment (GRACE) mass flux observations. However, SH signals are degraded by measurement and leakage errors. Mascon solutions (the Jet Propulsion Laboratory (JPL) release, herein) exhibit weakened signals at submascon resolutions. Both solutions require a scale factor examined by the CLM4.0 model to obtain the actual water storage signal. The Slepian localization method can avoid the SH leakage errors when applied to the basin scale. In this study, we estimate SH errors and scale factors for African hydrological regimes. Then, terrestrial water storage (TWS) in Africa is determined based on Slepian localization and compared with JPL-mascon and SH solutions. The three TWS estimates show good agreement for the TWS of large-sized and humid regimes but present discrepancies for the TWS of medium and small-sized regimes. Slepian localization is an effective method for deriving the TWS of arid zones. The TWS behavior in African regimes and its spatiotemporal variations are then examined. The negative TWS trends in the lower Nile and Sahara at −1.08 and −6.92 Gt/year, respectively, are higher than those previously reported. PMID:28287453
Enhancing wastewater reuse by forward osmosis with self-diluted commercial fertilizers as draw solutes.

PubMed

Zou, Shiqiang; He, Zhen

2016-08-01

Using fertilizers as draw solutes in forward osmosis (FO) can accomplish wastewater reuse with elimination of recycling draw solute. In this study, three commercial fast-release all-purpose solid fertilizers (F1, F2 and F3) were examined as draw solutes in a submerged FO system for water extraction from either deionized (DI) water or the treated wastewater. Systematic optimizations were conducted to enhance water extraction performance, including operation modes, initial draw concentrations and in-situ chemical fouling control. In the mode of the active layer facing the feed (AL-F or FO), a maximum of 324 mL water was harvested using 1-M F1, which provided 41% of the water need for fertilizer dilution for irrigation. Among the three fertilizers, F1 containing a lower urea content was the most favored because of a higher water extraction and a lower reverse solute flux (RSF) of major nutrients. Using the treated wastewater as a feed solution resulted in a comparable water extraction performance (317 mL) to that of DI water in 72 h and a maximum water flux of 4.2 LMH. Phosphorus accumulation on the feed side was mainly due to the FO membrane solute rejection while total nitrogen and potassium accumulation was mainly due to RSF from the draw solute. Reducing recirculation intensity from 100 to 10 mL min(-1) did not obviously decrease water flux but significantly reduced the energy consumption from 1.86 to 0.02 kWh m(-3). These results have demonstrated the feasibility of using commercial solid fertilizers as draw solutes for extracting reusable water from wastewater, and challenges such as reverse solute flux will need to be further addressed. Copyright © 2016 Elsevier Ltd. All rights reserved.
Lower critical solution temperature (LCST) phase separation of glycol ethers for forward osmotic control.

PubMed

Nakayama, Daichi; Mok, Yeongbong; Noh, Minwoo; Park, Jeongseon; Kang, Sunyoung; Lee, Yan

2014-03-21

Lower critical solution temperature (LCST) phase transition of glycol ether (GE)-water mixtures induces an abrupt change in osmotic pressure driven by a mild temperature change. The temperature-controlled osmotic change was applied for the forward osmosis (FO) desalination. Among three GEs evaluated, di(ethylene glycol) n-hexyl ether (DEH) was selected as a potential FO draw solute. A DEH-water mixture with a high osmotic pressure could draw fresh water from a high-salt feed solution such as seawater through a semipermeable membrane at around 10 °C. The water-drawn DEH-water mixture was phase-separated into a water-rich phase and a DEH-rich phase at around 30 °C. The water-rich phase with a much reduced osmotic pressure released water into a low-salt solution, and the DEH-rich phase was recovered into the initial DEH-water mixture. The phase separation behaviour, the residual GE concentration in the water-rich phase, the osmotic pressure of the DEH-water mixture, and the osmotic flux between the DEH-water mixture and salt solutions were carefully analysed for FO desalination. The liquid-liquid phase separation of the GE-water mixture driven by the mild temperature change between 10 °C and 30 °C is very attractive for the development of an ideal draw solute for future practical FO desalination.
Application of a colorimeter for turbidity measurement

NASA Astrophysics Data System (ADS)

Wen, Yizhang; Hu, Yingtian; Wang, Xiaoping

2016-02-01

This paper describes a new turbidity transducer based on color measurement. The absorbance of solutions reflects the absorption and scattering of suspended particle for incident light which could determine the turbidity of solutions. The experimental results indicate that there are good linear relationships between chromaticity and turbidity. The new way is suitable for continuous monitoring of water turbidity in the wide range.
Study on the water resources optimal operation based on riverbed wind erosion control in West Liaohe River plain

NASA Astrophysics Data System (ADS)

Wanguang, Sun; Chengzhen, Li; Baoshan, Fan

2018-06-01

Rivers are drying up most frequently in West Liaohe River plain and the bare river beds present fine sand belts on land. These sand belts, which yield a dust heavily in windy days, stress the local environment deeply as the riverbeds are eroded by wind. The optimal operation of water resources, thus, is one of the most important methods for preventing the wind erosion of riverbeds. In this paper, optimal operation model for water resources based on riverbed wind erosion control has been established, which contains objective function, constraints, and solution method. The objective function considers factors which include water volume diverted into reservoirs, river length and lower threshold of flow rate, etc. On the basis of ensuring the water requirement of each reservoir, the destruction of the vegetation in the riverbed by the frequent river flow is avoided. The multi core parallel solving method for optimal water resources operation in the West Liaohe River Plain is proposed, which the optimal solution is found by DPSA method under the POA framework and the parallel computing program is designed in Fork/Join mode. Based on the optimal operation results, the basic rules of water resources operation in the West Liaohe River Plain are summarized. Calculation results show that, on the basis of meeting the requirement of water volume of every reservoir, the frequency of reach river flow which from Taihekou to Talagan Water Diversion Project in the Xinkai River is reduced effectively. The speedup and parallel efficiency of parallel algorithm are 1.51 and 0.76 respectively, and the computing time is significantly decreased. The research results show in this paper can provide technical support for the prevention and control of riverbed wind erosion in the West Liaohe River plain.
Charge transfer complexes of adenosine-5‧-monophosphate and cytidine-5‧-monophosphate with water-soluble cobalt(II) Schiff base complexes in aqueous solution

NASA Astrophysics Data System (ADS)

Boghaei, Davar M.; Gharagozlou, Mehrnaz

2006-01-01

Water-soluble cobalt(II) tetradentate Schiff base complexes have been shown to form charge transfer (CT) complexes with a series of nucleoside monophosphates including adenosine-5‧-monophosphate (AMP) and cytidine-5‧-monophosphate (CMP). The investigated water-soluble cobalt(II) Schiff base complexes are (i) disodium[{bis(5-sulfo-salicylaldehyde)-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-salophen)] (1); (ii) disodium[{bis(5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-sal-4,5-dmophen)] (2) and (iii) disodium[{bis(4-methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-4-meosal-4,5-dmophen)] (3). The formation constant and thermodynamic parameters for charge transfer complex formation of water-soluble cobalt(II) Schiff base complexes with nucleoside monophosphates were determined spectrophotometrically in aqueous solution at constant ionic strength (I = 0.2 mol dm-3 KNO3) under physiological condition (pH 7.0) and at various temperatures between 288 and 308 K. The stoichiometry has been found to be 1:1 (water-soluble cobalt(II) Schiff base complex: nucleoside monophosphate) in each case. Our spectroscopic and thermodynamic results show that the interaction of water-soluble cobalt(II) Schiff base complexes with the investigated nucleoside monophosphates occurs mainly through the phosphate group. The trend of the interaction according to the cobalt(II) Schiff base complexes due to electronic and steric factors is as follows: Na2[Co(SO3-salophen)] > Na2[Co(SO3-sal-4,5-dmophen)] > Na2[Co(SO3-4-meosal-4,5-dmophen)]. Also the trend of the interaction of a given cobalt(II) Schiff base complex according to the nucleoside monophosphate is as follows: CMP > AMP.
Description of Adsorption in Liquid Chromatography under Nonideal Conditions.

PubMed

Ortner, Franziska; Ruppli, Chantal; Mazzotti, Marco

2018-05-15

A thermodynamically consistent description of binary adsorption in reversed-phase chromatography is presented, accounting for thermodynamic nonidealities in the liquid and adsorbed phases. The investigated system involves the adsorbent Zorbax 300SB-C18, as well as phenetole and 4- tert-butylphenol as solutes and methanol and water as inert components forming the eluent. The description is based on adsorption isotherms, which are a function of the liquid-phase activities, to account for nonidealities in the liquid phase. Liquid-phase activities are calculated with a UNIQUAC model established in this work, based on experimental phase equilibrium data. The binary interaction in the adsorbed phase is described by the adsorbed solution theory, assuming an ideal (ideal adsorbed solution theory) or real (real adsorbed solution theory) adsorbed phase. Implementation of the established adsorption model in a chromatographic code achieves a quantitative description of experimental elution profiles, with feed compositions exploiting the entire miscible region, and involving a broad range of different eluent compositions (methanol/water). The quantitative agreement of the model and experimental data serves as a confirmation of the underlying physical (thermodynamic) concepts and of their applicability to a broad range of operating conditions.
Temperature-assisted photochemical construction of CdS-based ordered porous films with photocatalytic activities on solution surfaces.

PubMed

Huang, Zhenxun; Sun, Fengqiang; Zhang, Yu; Gu, Kaiyuan; Zou, Xueqiong; Huang, Yuying; Wu, Qingsong; Zhang, Zihe

2011-04-15

Taking a colloidal monolayer floating on the surface of a precursor solution as template, free-standing CdS/Cd composites and pure CdS (CdS-based) ordered porous films had been prepared by a temperature-assisted photochemical strategy. After irradiation with UV-light and heat treatment, the films formed hemi-spherical pores due to the preferable deposition of CdS and Cd onto the PS spheres during the photochemical and interfacial reactions. When the temperature increased from 15 to 60°C, the air/water interface gradually changed into a vapor/water interface on the surface of the solution, resulting in variations of the final compositions. The optical properties of the films were hence changed. Because of the free-standing characteristic, the ordered porous films were first transferred on surface of polluted solutions as photocatalysts, which was a new mode in application of photocatalysts. The photocatalytic activities of films showed regular variations with the compositions in photodegradation of Rhodamine B. This method provides a simple route for tuning the properties of porous films through control of its composition and a flexible application of films on any surface. Copyright © 2011 Elsevier Inc. All rights reserved.
Facile synthesis of Fe3O4@C hollow nanospheres and their application in polluted water treatment

NASA Astrophysics Data System (ADS)

Zhang, Yuanguang; Xu, Shihao; Xia, Hongyu; Zheng, Fangcai

2016-11-01

Nanostructured carbon-based materials, such as carbon nanotube arrays have shown respectable removal ability for heavy metal ions and organic dyes in aqueous solution. Although the carbon-based materials exhibited excellent removal ability, the separation of them from the aqueous solution is difficult and time-consuming. Here we demonstrated a novel and facile route for the large-scale fabrication of Fe3O4@C hollow nanospheres, with using ferrocene as a single reagent and SiO2 as a template. The as-prepared Fe3O4@C hollow nanospheres exhibited adsorption ability for heavy metal ions and organic dyes from aqueous solution, and can be easily separated by an external magnet. When the as-prepared Fe3O4@C hollow nanospheres were mixed with the aqueous solution of Hg2+ within 15 min, the removal efficiency was 90.3%. The as-prepared Fe3O4@C hollow nanospheres were also exhibited a high adsorption capacity (100%) as the adsorbent for methylene blue (MB). In addition, the as-prepared Fe3O4@C hollow nanospheres can be used as the recyclable sorbent for water treatment via a simple magnetic separation.
Determination of the quaternary phase diagram of the water-ethylene glycol-sucrose-NaCl system and a comparison between two theoretical methods for synthetic phase diagrams

PubMed Central

Han, Xu; Liu, Yang; Critser, John K.

2010-01-01

Characterization of the thermodynamic properties of multi-solute aqueous solutions is of critical importance for biological and biochemical research. For example, the phase diagrams of aqueous systems, containing salts, saccharides, and plasma membrane permeating solutes, are indispensible in the field of cryobiology and pharmacology. However, only a few ternary phase diagrams are currently available for these systems. In this study, an auto-sampler differential scanning calorimeter (DSC) was used to determine the quaternary phase diagram of the water-ethylene glycol-sucrose-NaCl system. To improve the accuracy of melting point measurement, a “mass redemption” method was also applied for the DSC technique. Base on the analyses of these experimental data, a comparison was made between the two practical approaches to generate phase diagrams of multi-solute solutions from those of single-solute solutions: the summation of cubic polynomial melting point equations versus the use of osmotic virial equations with cross coefficients. The calculated values of the model standard deviations suggested that both methods are satisfactory for characterizing this quaternary system. PMID:20447385

Long-term environmental impacts of building composites containing waste materials: Evaluation of the leaching protocols.

PubMed

Drinčić, Ana; Nikolić, Irena; Zuliani, Tea; Milačič, Radmila; Ščančar, Janez

2017-01-01

The NEN 7375 test has been proposed for evaluating the long-term environmental impacts caused by the release of contaminants from monolithic building and waste materials. Over a period of 64days, at specific points in time, the leaching solution (demineralised water) is replenished. By applying the NEN 7375 test, leaching of contaminants that is based mainly on diffusion is followed. In the present work, the results from modified leaching protocols were evaluated against those obtained by NEN 7375 test. In modified protocols, synthetic sea, surface and MilliQ water were used for the leaching of selected elements and chromate, molybdate and vanadate from compact and ground building composites (98% mixture of fly ash (80%) and cement (20%), and 2% of electric arc furnace (EAF) dust) over 6months. The leaching solutions were not replenished, imitating both the diffusion and the dissolution of contaminants. The data revealed larger extent of leaching when the leaching solution was not replenished. More extensive was also leaching from ground composites, which simulated the disintegration of the material over time. The composition of the leaching solution influenced the release of the matrix constituents from the composites and, consequently, the amount of elements and their chemical species. Synthetic sea and surface water used as leaching solutions, without replenishing, were found to be suitable to simulate the conditions when the building material is immersed in stagnant environmental waters. Copyright © 2016 Elsevier Ltd. All rights reserved.
Partitioning of lysolipids, fatty acids and their mixtures in aqueous lipid bilayers: solute concentration/composition effects.

PubMed

Singh, Jasmeet; Lai, Amy Jo; Alaee, Yasmin; Ranganathan, Radha

2014-01-01

Distributions of lysopalmitoylphosphatidylcholine (LPPC), palmitic acid (PA) and their 1:1 mixtures between water and dipalmitoylphosphatidylcholine (DPPC) bilayer were determined using a fluorescence probe that selectively detects only the solutes in water. Water solute concentrations were obtained at each of several lipid concentrations. Dynamic Light Scattering experiments confirmed that the lipid/solute aggregates were vesicles in the concentration range investigated. Lipid concentration dependence of the solute component in water was fit to a thermodynamic model of solute distribution between two coexisting solvents. Water/bilayer partition coefficient and the free energy of transfer, for each of these solutes were determined from the fit. Main findings are: (1) Water/bilayer partition coefficient of solute is greater for 2 to 10% solute mole fraction than for 0 to 2%, signaling solute induced bilayer perturbation that increases bilayer solubility, beginning at 2% solute mole fraction. (2) Partition coefficients are in the order LPPC
Partitioning of Lysolipids, Fatty Acids and Their Mixtures in Aqueous Lipid Bilayers: Solute Concentration / Composition Effects

PubMed Central

Singh, Jasmeet; Lai, Amy Jo; Alaee, Yasmin; Ranganathan, Radha

2013-01-01

Distribution of lysopalmitoylphosphatidylcholine (LPPC), Palmitic acid (PA) and their 1:1 mixtures between water and dipalmitoylphosphatidylcholine (DPPC) bilayer were determined using a fluorescence probe that selectively detects only the solutes in water. Water solute concentrations were obtained at each of several lipid concentrations. Dynamic Light Scattering experiments confirmed that the lipid/solute aggregates were vesicles in the concentration range investigated. Lipid concentration dependence of the solute component in water was fit to a thermodynamic model of solute distribution between two coexisting solvents. Water/bilayer partition coefficient and the free energy of transfer, for each of these solutes were determined from the fit. Main findings are: (1) Water/bilayer partition coefficient of solute is greater for 2 to 10 % solute mole fraction than for 0 to 2 %, signaling solute induced bilayer perturbation that increases bilayer solubility, beginning at 2 % solute mole fraction. (2) Partition coefficients are in the order LPPC
NO3- Coordination in Aqueous Solutions by 15N/ 14N and 18O/natO Isotopic Substitution: What Can We Learn from Molecular Simulation?

DOE PAGES

Chialvo, Ariel A.; Vlcek, Lukas

2014-12-16

We explore the deconvolution of the water-nitrate correlations by the first-order difference approach involving neutron diffraction of heavy- and null-aqueous solutions of KNO 3 under 14N 15N and natON 18ON substitutions to achieve a full characterization of the first water coordination around the nitrate ion. For that purpose we performed isobaric-isothermal simulations of 3.5m KNO 3 aqueous solutions at ambient conditions to generate the relevant radial distribution functions (RDF) required in the analysis (a) to identify the individual partial contributions to the total neutron weighted distribution function, (b) to isolate and assess the contribution of NO 3 -!K + pairmore » formation, (c) to test the accuracy of the NDIS-based coordination calculations and XRDbased assumptions, and (d) to describe the water coordination around both the nitrogen and oxygen sites of the nitrate ion.« less
Preparation and characterization of poly(acrylic acid)—corn starch blend for use as chemical sand-fixing materials

NASA Astrophysics Data System (ADS)

Dang, Xugang; Chen, Hui; Shan, Zhihua

2017-07-01

One chemical sand-fixing materials based on poly(acrylic acid)-corn starch (PACS) blend was studied in this work. The PACS blend was prepared by solution mixing method between PA and CS. In order to prepare sand-fixing materials for environmental applications using the well-established method of spraying evenly PACS blend solution on the surfaces of fine sand. Fourier transform infrared spectroscopy (FT-IR) revealed the existence of the intermolecular interactions between the blend components. Scanning electron microscope (SEM) analysis showed a continuous phase of blend, and it also showed the good sand-fixing capacity. The test results of hygroscopicity and water retention experiments indicated that the blends had excellent water-absorbing and water-retention capacity. The results of contact angle measurements between the PACS solutions and fine sand showed that the PACS blend has a satisfactory effect on fine sand wetting. And the PACS, as a sand-fixation material, has excellent sand-fixation rate up to 99.5%.
Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters.

PubMed

Pathak, A K; Mukherjee, T; Maity, D K

2007-07-28

We report vertical detachment energy (VDE) and IR spectra of Br2.-.(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2.-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150 K. A linear relationship is obtained for VDE versus (n+3)(-1/3) and bulk VDE of Br2.- aqueous solution is calculated as 10.01 eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by approximately 0.5 eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by approximately 6.4 eV. Calculated IR spectra show that the formation of Br2.--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2.-.(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.
Theoretical studies on photoelectron and IR spectral properties of Br2.-(H2O)n clusters

NASA Astrophysics Data System (ADS)

Pathak, A. K.; Mukherjee, T.; Maity, D. K.

2007-07-01

We report vertical detachment energy (VDE) and IR spectra of Br2•-•(H2O)n clusters (n=1-8) based on first principles electronic structure calculations. Cluster structures and IR spectra are calculated at Becke's half-and-half hybrid exchange-correlation functional (BHHLYP) with a triple split valence basis function, 6-311++G(d,p). VDE for the hydrated clusters is calculated based on second order Moller-Plesset perturbation (MP2) theory with the same set of basis function. On full geometry optimization, it is observed that conformers having interwater hydrogen bonding among solvent water molecules are more stable than the structures having double or single hydrogen bonded structures between the anionic solute, Br2•-, and solvent water molecules. Moreover, a conformer having cyclic interwater hydrogen bonded network is predicted to be more stable for each size hydrated cluster. It is also noticed that up to four solvent H2O units can reside around the solute in a cyclic interwater hydrogen bonded network. The excess electron in these hydrated clusters is localized over the solute atoms. Weighted average VDE is calculated for each size (n) cluster based on statistical population of the conformers at 150K. A linear relationship is obtained for VDE versus (n+3)-1/3 and bulk VDE of Br2•- aqueous solution is calculated as 10.01eV at MP2 level of theory. BHHLYP density functional is seen to make a systematic overestimation in VDE values by ˜0.5eV compared to MP2 data in all the hydrated clusters. It is observed that hydration increases VDE of bromine dimer anion system by ˜6.4eV. Calculated IR spectra show that the formation of Br2•--water clusters induces large shifts from the normal O-H stretching bands of isolated water keeping bending modes rather insensitive. Hydrated clusters, Br2•-•(H2O)n, show characteristic sharp features of O-H stretching bands of water in the small size clusters.
Development and assessment of an efficient vadose zone module solving the 1D Richards' equation and including root extraction by plants

NASA Astrophysics Data System (ADS)

Varado, N.; Braud, I.; Ross, P. J.

2006-05-01

From the non iterative numerical method proposed by [Ross, P.J., 2003. Modeling soil water and solute transport—fast, simplified numerical solutions. Agronomy Journal 95, 1352-1361] for solving the 1D Richards' equation, an unsaturated zone module for large scale hydrological model is developed by the inclusion of a root extraction module and a formulation of interception. Two root water uptake modules, first proposed by [Lai, C.-T. and Katul, G., 2000. The dynamic role of rott-water uptake in coupling potential to actual transpiration. Adv. Water Res. 23: 427-439; Li, K.Y., De Jong, R. and Boisvert, J.B., 2001. An exponential root-water-uptake model with water stress compensation. J. Hydrol. 252: 189-204], were included as the sink term in the Richards' equation. They express root extraction as a linear function of potential transpiration and take into account water stress and compensation mechanism allowing water to be extracted in wetter layers. The vadose zone module is tested in a systematic way with synthetic data sets covering a wide range of soil characteristics, climate forcing, and vegetation cover. A detailed SVAT model providing an accurate solution of the coupled heat and water transfer in the soil and the surface energy balance is used as a reference. The accuracy of the numerical solution using only the SVAT soil module, and the loss of accuracy when using a potential evapotranspiration instead of solving the energy budget are both investigated. The vadose zone module is very accurate with errors of less than a few percent for cumulative transpiration. Soil evaporation is less accurately simulated as it leads to a systematic underestimation of soil evaporation amounts. The [Lai, C.-T. and Katul, G., 2000. The dynamic role of rott-water uptake in coupling potential to actual transpiration. Adv. Water Res. 23: 427-439] module is not adapted for sandy soils, due to a weakness in the compensation term formulation. When using a potential evapotranspiration instead of the surface energy balance, we evidenced a difference in partitioning the energy between the soil and the vegetation. A Beer-Lambert law is not able to take into account the complex interactions at the soil-vegetation-atmopshere interface. However, under field conditions, the accuracy of the vadose zone module is satisfactory provided that a correct crop coefficient could be defined. As a conclusion the numerical method proposed by [Ross, P.J., 2003. Modeling soil water and solute transport—fast, simplified numerical solutions. Agronomy Journal 95, 1352-1361] coupled with the [Li, K.Y., De Jong, R. and Boisvert, J.B., 2001. An exponential root-water-uptake model with water stress compensation. J. Hydrol. 252: 189-204] root extraction module provides an efficient and accurate solution for inclusion as a physically-based infiltration-evapotranspiration module into larger scale watershed models.
Water penetration of grommets: an in vitro study.

PubMed

Ibrahim, Yousef; Fram, Paul; Hughes, Gavin; Phillips, Pete; Owens, David

2017-10-01

The insertion of grommets has been one of the most common procedures carried out by ENT surgeons for patients with persistent middle ear fluid. There has always been apprehension at the use of grommets by patients undertaking swimming or other water sports due to concerns of grommet penetration by water into the middle ear. Despite this, no common consensus exists amongst otolaryngologists regarding post-operative advice following grommet insertion. Most studies focus on surface swimming and do not consider other activities such as diving that patients may undertake. This study aimed to determine the hydrostatic head required for water to pass through a grommet using different water-based solutions. These were selected to simulate conditions such as swimming and showering or bathing. An improved model of a grommeted middle ear (based on previous work by Ricks et al.) was constructed using two 5-ml plastic syringes, latex (from a surgical glove), two rubber neoprene membranes and a Shah Ventilation Tube (1.14 mm). Different water solutions were added to the system and the hydrostatic head measured using digital calipers. The results revealed that the hydrostatic head required to penetrate a grommet is lowest using soapy water and highest with distilled water. The differences between chlorinated water and 3% saline were not significant. We hope that this study can be used in conjunction with previous work to better prepare the ENT surgeon in giving suitable post-operative advice following grommet insertion.
A method of calculating quartz solubilities in aqueous sodium chloride solutions

USGS Publications Warehouse

Fournier, R.O.

1983-01-01

The aqueous silica species that form when quartz dissolves in water or saline solutions are hydrated. Therefore, the amount of quartz that will dissolve at a given temperature is influenced by the prevailing activity of water. Using a standard state in which there are 1,000 g of water (55.51 moles) per 1,000 cm3 of solution allows activity of water in a NaCl solution at high temperature to be closely approximated by the effective density of water, pe, in that solution, i.e. the product of the density of the NaCl solution times the weight fraction of water in the solution, corrected for the amount of water strongly bound to aqueous silica and Na+ as water of hydration. Generally, the hydration of water correction is negligible. The solubility of quartz in pure water is well known over a large temperature-pressure range. An empirical formula expresses that solubility in terms of temperature and density of water and thus takes care of activity coefficient and pressure-effect terms. Solubilities of quartz in NaCl solutions can be calculated by using that equation and substituting pe, for the density of pure water. Calculated and experimentally determined quartz solubilities in NaCl solutions show excellent agreement when the experiments were carried out in non-reactive platinum, gold, or gold plus titanium containers. Reactive metal containers generally yield dissolved silica concentrations higher than calculated, probably because of the formation of metal chlorides plus NaOH and H2. In the absence of NaOH there appears to be no detectable silica complexing in NaCl solutions, and the variation in quartz solubility with NaCl concentration at constant temperature can be accounted for entirely by variations in the activity of water. The average hydration number per molecule of dissolved SiO2 in liquid water and NaCl solutions decreases from about 2.4 at 200??C to about 2.1 at 350??C. This suggests that H4SiO4 may be the dominant aqueous silica species at 350??C, but other polymeric forms become important at lower temperatures. ?? 1983.
Hybrid MC/QC simulations of water-assisted proton transfer in nucleosides. Guanosine and its analog acyclovir.

PubMed

Markova, Nadezhda; Pejov, Ljupco; Stoyanova, Nina; Enchev, Venelin

2017-05-01

To provide an in-depth insight into the molecular basis of spontaneous tautomerism in DNA and RNA base pairs, a hybrid Monte Carlo (MC)-quantum chemical (QC) methodology is implemented to map two-dimensional potential energy surfaces along the reaction coordinates of solvent-assisted proton transfer processes in guanosine and its analog acyclovir in aqueous solution. The solvent effects were simulated by explicit inclusion of water molecules that model the relevant part of the first hydration shell around the solute. The position of these water molecules was estimated by carrying out a classical Metropolis Monte Carlo simulation of dilute water solutions of the guanosine (Gs) and acyclovir (ACV) and subsequently analyzing solute-solvent intermolecular interactions in the statistically-independent MC-generated configurations. The solvent-assisted proton transfer processes were further investigated using two different ab initio MP2 quantum chemical approaches. In the first one, potential energy surfaces of the 'bare' finite solute-solvent clusters containing Gs/ACV and four water molecules (MP2/6-31+G(d,p) level) were explored, while within the second approach, these clusters were embedded in 'bulk' solvent treated as polarizable continuum (C-PCM/MP2/6-31+G(d,p) level of theory). It was found that in the gas phase and in water solution, the most stable tautomer for guanosine and acyclovir is the 1H-2-amino-6-oxo form followed by the 2-amino-6-(sZ)-hydroxy form. The energy barriers of the water-assisted proton transfer reaction in guanosine and in acyclovir are found to be very similar - 11.74 kcal mol -1 for guanosine and 11.16 kcal mol -1 for acyclovir, and the respective rate constants (k = 1.5 × 10 1 s -1 , guanosine and k = 4.09 × 10 1 s -1 , acyclovir), are sufficiently large to generate the 2-amino-6-(sZ)-hydroxy tautomer. The analysis of the reaction profiles in both compounds shows that the proton transfer processes occur through the asynchronous concerted mechanism.
Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

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

Cochrane, T. T., E-mail: agteca@hotmail.com; Cochrane, T. A., E-mail: tom.cochrane@canterbury.ac.nz

Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their newmore » equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N{sub f},” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N{sub f} was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N{sub f}, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N{sub f} using recorded relative density data at 20 °C. They were subsequently used to estimate N{sub f} values at temperatures up to and excess of body temperatures. Those values, together with t values at temperatures up to and in excess of body temperatures recorded in the literature, were substituted in the authors’ equation for the provisional calculation of osmotic potentials. The calculations indicated that solution temperatures and solute concentrations have a marked effect on osmotic potentials. Conclusions: Following work to measure the relative densities of aqueous solutions for the calculation of N{sub f} values and the determination of definitive t values up to and beyond bodily temperatures, the authors’ equation would enable the accurate estimations of the osmotic potentials of wide concentrations of aqueous solutions of inorganic and organic solutes over the temperature range. The study illustrates that not only solute concentrations but also temperatures have a marked effect on osmotic potentials, an observation of medical and biological significance.« less
Corrosion inhibitor for aqueous ammonia absorption system

DOEpatents

Phillips, Benjamin A.; Whitlow, Eugene P.

1998-09-22

A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.
Corrosion inhibitor for aqueous ammonia absorption system

DOEpatents

Phillips, B.A.; Whitlow, E.P.

1998-09-22

A method is described for inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425 F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25 C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425 F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer. 5 figs.
Current advancements and challenges in soil-root interactions modelling

NASA Astrophysics Data System (ADS)

Schnepf, Andrea; Huber, Katrin; Abesha, Betiglu; Meunier, Felicien; Leitner, Daniel; Roose, Tiina; Javaux, Mathieu; Vanderborght, Jan; Vereecken, Harry

2015-04-01

Roots change their surrounding soil chemically, physically and biologically. This includes changes in soil moisture and solute concentration, the exudation of organic substances into the rhizosphere, increased growth of soil microorganisms, or changes in soil structure. The fate of water and solutes in the root zone is highly determined by these root-soil interactions. Mathematical models of soil-root systems in combination with non-invasive techniques able to characterize root systems are a promising tool to understand and predict the behaviour of water and solutes in the root zone. With respect to different fields of applications, predictive mathematical models can contribute to the solution of optimal control problems in plant recourse efficiency. This may result in significant gains in productivity, efficiency and environmental sustainability in various land use activities. Major challenges include the coupling of model parameters of the relevant processes with the surrounding environment such as temperature, nutrient concentration or soil water content. A further challenge is the mathematical description of the different spatial and temporal scales involved. This includes in particular the branched structures formed by root systems or the external mycelium of mycorrhizal fungi. Here, reducing complexity as well as bridging between spatial scales is required. Furthermore, the combination of experimental and mathematical techniques may advance the field enormously. Here, the use of root system, soil and rhizosphere models is presented through a number of modelling case studies, including image based modelling of phosphate uptake by a root with hairs, model-based optimization of root architecture for phosphate uptake from soil, upscaling of rhizosphere models, modelling root growth in structured soil, and the effect of root hydraulic architecture on plant water uptake efficiency and drought resistance.
Simulation of saltwater movement in the Upper Floridan aquifer in the Savannah, Georgia-Hilton Head Island, South Carolina, area, predevelopment-2004, and projected movement for 2000 pumping conditions

USGS Publications Warehouse

Provost, Alden M.; Payne, Dorothy F.; Voss, Clifford I.

2006-01-01

A digital model was developed to simulate ground-water flow and solute transport for the Upper Floridan aquifer in the Savannah, Georgia-Hilton Head Island, South Carolina, area. The model was used to (1) simulate trends of saltwater intrusion from predevelopment to the present day (1885-2004), (2) project these trends from the present day into the future, and (3) evaluate the relative influence of different assumptions regarding initial and boundary conditions and physical properties. The model is based on a regional, single-density ground-water flow model of coastal Georgia and adjacent parts of South Carolina and Florida. Variable-density ground-water flow and solute transport were simulated using the U.S. Geological Survey finite-element, variable-density solute-transport simulator SUTRA, 1885-2004. The model comprises seven layers: the surficial aquifer system, the Brunswick aquifer system, the Upper Floridan aquifer, the Lower Floridan aquifer, and the intervening confining units. The model was calibrated to September 1998 water levels, for single-density freshwater conditions, then refined using variable density and chloride concentration to give a reasonable match to the trend in the chloride distribution in the Upper Floridan aquifer inferred from field measurements of specific conductance made during 2000, 2002, 2003, and 2004. The model was modified to simulate solute transport by allowing saltwater to enter the system through localized areas near the northern end of Hilton Head Island, at Pinckney Island, and near the Colleton River, and was calibrated to match chloride concentrations inferred from field measurements of specific conductance. This simulation is called the 'Base Case.'
Current Advancements and Challenges in Soil-Root Interactions Modelling

NASA Astrophysics Data System (ADS)

Schnepf, A.; Huber, K.; Abesha, B.; Meunier, F.; Leitner, D.; Roose, T.; Javaux, M.; Vanderborght, J.; Vereecken, H.

2014-12-01

Roots change their surrounding soil chemically, physically and biologically. This includes changes in soil moisture and solute concentration, the exudation of organic substances into the rhizosphere, increased growth of soil microorganisms, or changes in soil structure. The fate of water and solutes in the root zone is highly determined by these root-soil interactions. Mathematical models of soil-root systems in combination with non-invasive techniques able to characterize root systems are a promising tool to understand and predict the behaviour of water and solutes in the root zone. With respect to different fields of applications, predictive mathematical models can contribute to the solution of optimal control problems in plant recourse efficiency. This may result in significant gains in productivity, efficiency and environmental sustainability in various land use activities. Major challenges include the coupling of model parameters of the relevant processes with the surrounding environment such as temperature, nutrient concentration or soil water content. A further challenge is the mathematical description of the different spatial and temporal scales involved. This includes in particular the branched structures formed by root systems or the external mycelium of mycorrhizal fungi. Here, reducing complexity as well as bridging between spatial scales is required. Furthermore, the combination of experimental and mathematical techniques may advance the field enormously. Here, the use of root system, soil and rhizosphere models is presented through a number of modelling case studies, including image based modelling of phosphate uptake by a root with hairs, model-based optimization of root architecture for phosphate uptake from soil, upscaling of rhizosphere models, modelling root growth in structured soil, and the effect of root hydraulic architecture on plant water uptake efficiency and drought resistance.
Consistency of patterns in concentration‐discharge plots

USGS Publications Warehouse

Chanat, Jeffrey G.; Rice, Karen C.; Hornberger, George M.

2002-01-01

Concentration‐discharge (c‐Q) plots have been used to infer how flow components such as event water, soil water, and groundwater mix to produce the observed episodic hydrochemical response of small catchments. Because c‐Q plots are based only on observed streamflow and solute concentration, their interpretation requires assumptions about the relative volume, hydrograph timing, and solute concentration of the streamflow end‐members. Evans and Davies [1998] present a taxonomy of c‐Q loops resulting from three‐component conservative mixing. Their analysis, based on a fixed template of end‐member hydrograph volume, timing, and concentration, suggests a unique relationship between c‐Q loop form and the rank order of end‐member concentrations. Many catchments exhibit variability in component contributions to storm flow in response to antecedent conditions or rainfall characteristics, but the effects of such variation on c‐Q relationships have not been studied systematically. Starting with a “baseline” condition similar to that assumed by Evans and Davies [1998], we use a simple computer model to characterize the variability in c‐Q plot patterns resulting from variation in end‐member volume, timing, and solute concentration. Variability in these three factors can result in more than one c‐Q loop shape for a given rank order of end‐member solute concentrations. The number of resulting hysteresis patterns and their relative frequency depends on the rank order of solute concentrations and on their separation in absolute value. In ambiguous cases the c‐Q loop shape is determined by the relative “prominence” of the event water versus soil water components. This “prominence” is broadly defined as a capacity to influence the total streamflow concentration and may result from a combination of end‐member volume, timing, or concentration. The modeling results indicate that plausible hydrological variability in field situations can confound the interpretation of c‐Q plots, even when fundamental end‐member mixing assumptions are satisfied.
Water-enhanced solvation of organic solutes in ketone and ester solvents

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

Lee, J.H.; Brunt, V. van; King, C.J.

1994-05-01

Previous research has shown that the solubilities of dicarboxylic acids in certain electron-donor solvents are substantially increased in the presence of water. Information on solubilities, liquid-liquid equilibria and maximum-boiling ternary azeotropes was screened so as to identify other systems where codissolved water appears to enhance solvation of organic solutes in solvents. Several carboxylic acids, an alcohol, diols, and phenols were selected for examination as solutes in ketone and ester solvents. Effects of water upon solute solubilities and volatilities were measured. Results showed that water-enhanced solvation is greatest for carboxylic acids. Solute activity coefficients decreased by factors of 2--3, 6--8, andmore » 7--10 due to the presence of water for mono-, di and tricarboxylic acids, respectively. Activity coefficients decreased by a factor of about 1.5 for ethanol and 1,2-propanediol as solutes. Water-enhanced solvation of phenols is small, when existent.« less
"Periodic-table-style" paper device for monitoring heavy metals in water.

PubMed

Li, Miaosi; Cao, Rong; Nilghaz, Azadeh; Guan, Liyun; Zhang, Xiwang; Shen, Wei

2015-03-03

If a paper-based analytical device (μ-PAD) could be made by printing indicators for detection of heavy metals in chemical symbols of the metals in a style of the periodic table of elements, it could be possible for such μ-PAD to report the presence and the safety level of heavy metal ions in water simultaneously and by text message. This device would be able to provide easy solutions to field-based monitoring of heavy metals in industrial wastewater discharges and in irrigating and drinking water. Text-reporting could promptly inform even nonprofessional users of the water quality. This work presents a proof of concept study of this idea. Cu(II), Ni(II), and Cr(VI) were chosen to demonstrate the feasibility, specificity, and reliability of paper-based text-reporting devices for monitoring heavy metals in water.

A new class of draw solutions for minimizing reverse salt flux to improve forward osmosis desalination.

PubMed

Nguyen, Hau Thi; Nguyen, Nguyen Cong; Chen, Shiao-Shing; Ngo, Huu Hao; Guo, Wenshan; Li, Chi-Wang

2015-12-15

The applications of forward osmosis (FO) have been hindered because of the lack of an optimal draw solution. The reverse salt flux from the draw solution not only reduces the water flux but also increases the cost of draw solute replenishment. Therefore, in this study, Tergitol NP7 and NP9 with a long straight carbon chain and low critical micelle concentration (CMC) were coupled with highly charged ethylenediaminetetraacetic acid (EDTA) as an innovative draw solution to minimize reverse salt diffusion in FO for the first time. The results showed that the lowest reverse salt flux of 0.067 GMH was observed when 0.1M EDTA-2Na coupled with 15mM NP7 was used as a draw solution and deionized water was used as a feed solution in FO mode (active layer facing with the feed solution). This is due to the hydrophobic interaction between the tails of NP7 and the FO membrane, thus creating layers on the membrane surface and constricting the FO membrane pores. Moreover, 1M EDTA-2Na coupled with 15mM NP7 is promising as an optimal draw solution for brackish water and sea water desalination. Average water fluxes of 7.68, 6.78, and 5.95 LMH were achieved when brackish water was used as a feed solution (5, 10, and 20g/L NaCl), and an average water flux of 3.81 LMH was achieved when sea water was used as a feed solution (35g/L NaCl). The diluted draw solution was recovered using a nanofiltration (NF-TS80) membrane with a high efficiency of 95% because of the high charge and large size of the draw solution. Copyright © 2015 Elsevier B.V. All rights reserved.
Investigation of the performance behavior of a forward osmosis membrane system using various feed spacer materials fabricated by 3D printing technique.

PubMed

Yanar, Numan; Son, Moon; Yang, Eunmok; Kim, Yeji; Park, Hosik; Nam, Seung-Eun; Choi, Heechul

2018-07-01

Recently, feed spacer research for improving the performance of a membrane module has adopted three-dimensional (3D) printing technology. This study aims to improve the performance of membrane feed spacers by using various materials and incorporating 3D printing. The samples were fabricated after modeling with 3D computer-aided design (CAD) software to investigate the mechanical strength, water flux, reverse solute flux, and fouling performances. This research was performed using acrylonitrile butadiene styrene (ABS), polypropylene (PP), and natural polylactic acid (PLA) as printing material, and the spacer model was produced using a diamond-shaped feed spacer, with a commercially available product as a reference. The 3D printed samples were initially compared in terms of size and precision with the 3D CAD model, and deviations were observed between the products and the CAD model. Then, the spacers were tested in terms of mechanical strength, water flux, reverse solute flux, and fouling (alginate-based waste water was used as a model foulant). Although there was not much difference among the samples regarding the water flux, better performances than the commercial product were obtained for reverse solute flux and fouling resistance. When comparing the prominent performance of natural PLA with the commercial product, PLA was found to have approximately 10% less fouling (based on foulant volume per unit area and root mean square roughness values), although it showed similar water flux. Thus, another approach has been introduced for using bio-degradable materials for membrane spacers. Copyright © 2018 Elsevier Ltd. All rights reserved.
WATSFAR: numerical simulation of soil WATer and Solute fluxes using a FAst and Robust method

NASA Astrophysics Data System (ADS)

Crevoisier, David; Voltz, Marc

2013-04-01

To simulate the evolution of hydro- and agro-systems, numerous spatialised models are based on a multi-local approach and improvement of simulation accuracy by data-assimilation techniques are now used in many application field. The latest acquisition techniques provide a large amount of experimental data, which increase the efficiency of parameters estimation and inverse modelling approaches. In turn simulations are often run on large temporal and spatial domains which requires a large number of model runs. Eventually, despite the regular increase in computing capacities, the development of fast and robust methods describing the evolution of saturated-unsaturated soil water and solute fluxes is still a challenge. Ross (2003, Agron J; 95:1352-1361) proposed a method, solving 1D Richards' and convection-diffusion equation, that fulfil these characteristics. The method is based on a non iterative approach which reduces the numerical divergence risks and allows the use of coarser spatial and temporal discretisations, while assuring a satisfying accuracy of the results. Crevoisier et al. (2009, Adv Wat Res; 32:936-947) proposed some technical improvements and validated this method on a wider range of agro- pedo- climatic situations. In this poster, we present the simulation code WATSFAR which generalises the Ross method to other mathematical representations of soil water retention curve (i.e. standard and modified van Genuchten model) and includes a dual permeability context (preferential fluxes) for both water and solute transfers. The situations tested are those known to be the less favourable when using standard numerical methods: fine textured and extremely dry soils, intense rainfall and solute fluxes, soils near saturation, ... The results of WATSFAR have been compared with the standard finite element model Hydrus. The analysis of these comparisons highlights two main advantages for WATSFAR, i) robustness: even on fine textured soil or high water and solute fluxes - where Hydrus simulations may fail to converge - no numerical problem appears, and ii) accuracy of simulations even for loose spatial domain discretisations, which can only be obtained by Hydrus with fine discretisations.
The energy balance within a bubble column evaporator

NASA Astrophysics Data System (ADS)

Fan, Chao; Shahid, Muhammad; Pashley, Richard M.

2018-05-01

Bubble column evaporator (BCE) systems have been studied and developed for many applications, such as thermal desalination, sterilization, evaporative cooling and controlled precipitation. The heat supplied from warm/hot dry bubbles is to vaporize the water in various salt solutions until the solution temperature reaches steady state, which was derived into the energy balance of the BCE. The energy balance and utilization involved in each BCE process form the fundamental theory of these applications. More importantly, it opened a new field for the thermodynamics study in the form of heat and vapor transfer in the bubbles. In this paper, the originally derived energy balance was reviewed on the basis of its physics in the BCE process and compared with new proposed energy balance equations in terms of obtained the enthalpy of vaporization (Δ H vap) values of salt solutions from BCE experiments. Based on the analysis of derivation and Δ H vap values comparison, it is demonstrated that the original balance equation has high accuracy and precision, within 2% over 19-55 °C using improved systems. Also, the experimental and theoretical techniques used for determining Δ H vap values of salt solutions were reviewed for the operation conditions and their accuracies compared to the literature data. The BCE method, as one of the most simple and accurate techniques, offers a novel way to determine Δ H vap values of salt solutions based on its energy balance equation, which had error less than 3%. The thermal energy required to heat the inlet gas, the energy used for water evaporation in the BCE and the energy conserved from water vapor condensation were estimated in an overall energy balance analysis. The good agreement observed between input and potential vapor condensation energy illustrates the efficiency of the BCE system. Typical energy consumption levels for thermal desalination for producing pure water using the BCE process was also analyzed for different inlet air temperatures, and indicated the better energy efficiency, of 7.55 kW·h per m3 of pure water, compared to traditional thermal desalination techniques.
Cost versus life cycle assessment-based environmental impact optimization of drinking water production plants.

PubMed

Capitanescu, F; Rege, S; Marvuglia, A; Benetto, E; Ahmadi, A; Gutiérrez, T Navarrete; Tiruta-Barna, L

2016-07-15

Empowering decision makers with cost-effective solutions for reducing industrial processes environmental burden, at both design and operation stages, is nowadays a major worldwide concern. The paper addresses this issue for the sector of drinking water production plants (DWPPs), seeking for optimal solutions trading-off operation cost and life cycle assessment (LCA)-based environmental impact while satisfying outlet water quality criteria. This leads to a challenging bi-objective constrained optimization problem, which relies on a computationally expensive intricate process-modelling simulator of the DWPP and has to be solved with limited computational budget. Since mathematical programming methods are unusable in this case, the paper examines the performances in tackling these challenges of six off-the-shelf state-of-the-art global meta-heuristic optimization algorithms, suitable for such simulation-based optimization, namely Strength Pareto Evolutionary Algorithm (SPEA2), Non-dominated Sorting Genetic Algorithm (NSGA-II), Indicator-based Evolutionary Algorithm (IBEA), Multi-Objective Evolutionary Algorithm based on Decomposition (MOEA/D), Differential Evolution (DE), and Particle Swarm Optimization (PSO). The results of optimization reveal that good reduction in both operating cost and environmental impact of the DWPP can be obtained. Furthermore, NSGA-II outperforms the other competing algorithms while MOEA/D and DE perform unexpectedly poorly. Copyright © 2016 Elsevier Ltd. All rights reserved.
The transport dynamics of chloride and sodium in a ladder fen during a continuous wastewater polishing experiment

NASA Astrophysics Data System (ADS)

McCarter, Colin P. R.; Price, Jonathan S.

2017-06-01

Ladder fen peatlands have excellent potential for wastewater polishing as they naturally contain both open water (pools) and subsurface (peat) treatment landforms; however, there is a poor understanding of solute transport in ladder fens with and without the increased hydrological load imposed by wastewater discharge. To better understand solute transport in ladder fens under wastewater polishing conditions a continuous solute (NaCl) tracer experiment (38 m3 day-1 of water, chloride - 47.2 mg L-1, and sodium - 25.3 mg L-1) was conducted during the summer of 2014 (day of year 192-243) in a small ladder fen in the James Bay Lowland. The transmissivity distribution and effective porosity (average 0.5) of the peat ribs were determined through repeated bail tests and the drainable porosity of 18 peat cores at -100 mb, respectively. Water samples were taken at least every 7 days to capture the solute (sodium and chloride) plumes. Both solute plumes never reached the site outflow (∼250 m downgradient) and displayed complex plume morphology, typically following the patterns of higher hydraulic conductivity within the upper 0.1 m of the saturated peat, rather than the microtopography. Based on the 50% breakthrough isotherms, sodium and chloride were transported at an average solute velocity of 1.9 and 1.1 m day-1, respectively (average linear groundwater velocity = 2.1 m day-1); thus, the solutes were retarded by a factor of 2.1 and 1.2 for sodium and chloride, respectively. Due to the inherent retardation of solutes into inactive pores and relatively high solute residence times, this study demonstrates the potential for wastewater polishing in ladder fens.
Binary breath figures for straightforward and controllable self-assembly of microspherical caps.

PubMed

Gong, Jianliang; Xu, Bingang; Tao, Xiaoming; Li, Lei

2016-05-11

The intense interest surrounding asymmetrical microparticles originates from their unique anisotropic properties and promising applications. In this work, direct self-assembly of polymeric microspherical caps without the assistance of any additives has been achieved by using low-surface-tension methanol (MeOH) and high-surface-tension water as binary breath figures (BFs). With the evaporation of polystyrene (PS) solution containing low-boiling-point solvent in the binary vapors, the formed MeOH BFs could quickly diffuse into solution, while water BFs tended to remain at the solution surface. This led to the formation of a gradient nonsolvent layer at the vapor/solution interface, which induced the formation of nuclei and guided further asymmetrical growth of polymer particles. After the spontaneous removal of MeOH, water and residual solvent by evaporation, polymeric microspherical caps were left on the substrate. Through controlling the proportion of water introduced by adjusting the ratios of MeOH and water, polymeric microspherical caps with a range of controllable shapes (divided at different positions of a sphere) were successfully obtained. The formation mechanism was explained based on the difference of vapor pressure, surface tension and miscibility between the employed solvents and nonsolvents. A solvent possessing a high vapor pressure, low surface tension and good miscibility with MeOH contributed to the formation of microspherical caps. This flexible, green and straightforward technique is a nondestructive strategy, and avoids complicated work on design, preparation and removal of hard templates and additives.
Dynamic Stackelberg game model for water rationalization in drought emergency

NASA Astrophysics Data System (ADS)

Kicsiny, R.; Piscopo, V.; Scarelli, A.; Varga, Z.

2014-09-01

In water resource management, in case of a limited resource, there is a conflict situation between different consumers. In this paper, a dynamic game-theoretical model is suggested for the solution of such conflict. Let us suppose that in a region, water supply is based on a given aquifer, from which a quantity of effective reserve can be used without damaging the aquifer, and a long drought is foreseen. The use of water is divided between the social sector represented by the local authority, and the production sector, in our case, simplified to a single agricultural producer using water for irrigation; they are the players in the game. For a fixed time period, every day, a given amount is available, from which first the authority, then the producer takes a proportion, which corresponds to the strategy choices of the players. A price function is given, which depends on the total available reserve, the payoffs of both players are quantified as their net incomes for the whole period: for the producer: profit from selling the product minus price of water and tax paid, for the authority: tax received plus the gain for the authority from selling the water bought to the social sector minus price of water purchased. A solution (equilibrium) of the game consists of such strategy choices of both players, with which each player maximizes her/his total payoff (over the whole time horizon of the game) provided that the other player also maximizes her/his own payoff. In the paper, in a mathematical model for the above conflict situation, a deterministic continuum-strategy two-player discrete-time dynamic Stackelberg game with fixed finite time duration and closed-loop information structure is proposed, where the authority is “leader” and the producer is “follower”. The algorithms for the solution of the game are based on recent theoretical results of the authors. Illustrative numerical examples are also given.
Preferable removal of phosphate from water using hydrous zirconium oxide-based nanocomposite of high stability.

PubMed

Chen, Liang; Zhao, Xin; Pan, Bingcai; Zhang, Weixian; Hua, Ming; Lv, Lu; Zhang, Weiming

2015-03-02

In this study, we employed a new nanocomposite adsorbent HZO-201, which featured high stability under varying solution chemistry, for preferable removal of phosphate from synthetic solution and a real effluent. An anion exchange resin (D-201) was employed as the host of HZO-201, where nano-hydrous zirconium oxide (HZO) was encapsulated as the active species. D-201 binds phosphate through nonspecific electrostatic affinity, whereas the loaded HZO nanoparticles capture phosphate through formation of the inner-sphere complexes. Quantitative contribution of both species to phosphate adsorption was predicted based on the double-Langmuir model. Preferable removal of phosphate by HZO-201 was observed in the presence of the competing anions at higher levels (Cl(-), NO3(-), SO4(2-), HCO3(-)). Fixed-bed adsorption indicated that the effective volume capacity of a synthetic water (2.0 mg P-PO4(3-)/L) by using HZO-201 was ∼1600 BV in the first run (<0.5mg P-PO4(3-)/L), comparable to Fe(III)-based nanocomposite HFO-201 (∼1500 BV) and much larger than D-201 (<250 BV). The exhausted HZO-201 can be in situ regenerated by using a binary NaOH-NaCl solution for cyclic runs, whether fed with the synthetic solution or real effluent. In general, HZO-201 is a promising alternative to Fe(III)-based adsorbents for trace phosphate removal from effluent particularly at acidic pH. Copyright © 2014 Elsevier B.V. All rights reserved.
Electrooxidation of organics in waste water

NASA Technical Reports Server (NTRS)

Hitchens, G. D.; Murphy, Oliver J.; Kaba, Lamine; Verostko, Charles E.

1990-01-01

Electrooxidation is a means of removing organic solutes directly from waste waters without the use of chemical expendables. Research sponsored by NASA is currently being pursued to demonstrate the feasibility of the concept for oxidation of organic impurities common to urine, shower waters and space-habitat humidity condensates. Electrooxidation of urine and waste water ersatz was experimentally demonstrated. This paper discusses the electrooxidation principle, reaction kinetics, efficiency, power, size, experimental test results and water-reclamation applications. Process operating potentials and the use of anodic oxidation potentials that are sufficiently low to avoid oxygen formation and chloride oxidation are described. The design of an electrochemical system that incorporates a membrane-based electrolyte based on parametric test data and current fuel-cell technology is presented.
Droplet-Based Production of Liposomes

NASA Technical Reports Server (NTRS)

Ackley, Donald E.; Forster, Anita

2009-01-01

A process for making monodisperse liposomes having lipid bilayer membranes involves fewer, simpler process steps than do related prior methods. First, a microfluidic, cross junction droplet generator is used to produce vesicles comprising aqueous solution droplets contained in single layer lipid membranes. The vesicles are collected in a lipid-solvent mix that is at most partially soluble in water and is less dense than is water. A layer of water is dispensed on top of the solvent. By virtue of the difference in densities, the water sinks to the bottom and the solvent floats to the top. The vesicles, which have almost the same density as that of water, become exchanged into the water instead of floating to the top. As there are excess lipids in the solvent solution, in order for the vesicles to remain in the water, the addition of a second lipid layer to each vesicle is energetically favored. The resulting lipid bilayers present the hydrophilic ends of the lipid molecules to both the inner and outer membrane surfaces. If lipids of a second kind are dissolved in the solvent in sufficient excess before use, then asymmetric liposomes may be formed.
Water Treatment and Handwashing Behaviors among Non-Pregnant Friends and Relatives of Participants in an Antenatal Hygiene Promotion Program in Malawi

PubMed Central

Russo, Elizabeth T.; Sheth, Anandi; Menon, Manoj; Wannemuehler, Kathleen; Weinger, Merri; Kudzala, Amose C.; Tauzie, Blessius; Masuku, Humphreys D.; Msowoya, Tapona E.; Quick, Robert

2012-01-01

Access to safe drinking water and improved hygiene are essential for preventing diarrheal diseases. To integrate hygiene improvement with antenatal care, free hygiene kits (water storage containers, water treatment solution, soap) and educational messages were distributed to pregnant women at antenatal clinics in Malawi. We assessed water treatment and hygiene practices of 275 non-pregnant friends and relatives of the hygiene kit recipients at baseline and follow-up nine months later to measure program impact on non-participants in the same communities. At follow-up, friends and relatives who did not receive kits or education were more likely than at baseline to purchase and use water treatment solution (25% versus 1%; P < 0.0001) and demonstrate correct handwashing practices (60% versus 18%; P < 0.0001). This antenatal clinic–based program resulted in improved water treatment and hygiene behaviors among non-pregnant friends and relatives living in the same communities as hygiene kit recipients, suggesting that program benefits extended beyond direct beneficiaries. PMID:22556088
Droplet-based microfluidics platform for measurement of rapid erythrocyte water transport

PubMed Central

Jin, Byung-Ju; Esteva-Font, Cristina; Verkman, A.S.

2015-01-01

Cell membrane water permeability is an important determinant of epithelial fluid secretion, tissue swelling, angiogenesis, tumor spread and other biological processes. Cellular water channels, the aquaporins, are important drug targets. Water permeability is generally measured from the kinetics of cell volume change in response to an osmotic gradient. Here, we developed a microfluidics platform in which cells expressing a cytoplasmic, volume-sensing fluorescent dye are rapidly subjected to an osmotic gradient by solution mixing inside a ~ 0.1 nL droplet surrounded by oil. Solution mixing time was < 10 ms. Osmotic water permeability was deduced from a single, time-integrated fluorescence image of an observation area in which time after mixing is determined by spatial position. Water permeability was accurately measured in aquaporin-expressing erythrocytes with half-times for osmotic equilibration down to < 50 ms. Compared with conventional water permeability measurements using costly stopped-flow instrumentation, the microfluidics platform here utilizes sub-microliter blood sample volume, does not suffer from mixing artifact, and replaces challenging kinetic measurements by a single image capture using a standard laboratory fluorescence microscope. PMID:26159099
Quality assessment of plant transpiration water

NASA Technical Reports Server (NTRS)

Macler, Bruce A.; Janik, Daniel S.; Benson, Brian L.

1990-01-01

It has been proposed to use plants as elements of biologically-based life support systems for long-term space missions. Three roles have been brought forth for plants in this application: recycling of water, regeneration of air and production of food. This report discusses recycling of water and presents data from investigations of plant transpiration water quality. Aqueous nutrient solution was applied to several plant species and transpired water collected. The findings indicated that this water typically contained 0.3-6 ppm of total organic carbon, which meets hygiene water standards for NASA's space applications. It suggests that this method could be developed to achieve potable water standards.
Foliar uptake of radiocaesium from irrigation water by paddy rice (Oryza sativa): an overlooked pathway in contaminated environments.

PubMed

Uematsu, Shinichiro; Vandenhove, Hildegarde; Sweeck, Lieve; Hees, May Van; Wannijn, Jean; Smolders, Erik

2017-04-01

Flooded (paddy) rice (Oryza sativa) can take up ions from the irrigation water by foliar uptake via the exposed stem base. We hypothesised that the stem base uptake of radiocaesium (RCs) is a pathway for rice grown in RCs-contaminated environments. We developed a bi-compartmental device which discriminates the stem base from root RCs uptake from solutions, thereby using RCs isotopes ( 137 Cs and 134 Cs) with < 2% solution leak between the compartments. Radiocaesium uptake was linear over time (0-24 h). Radiocaesium uptake to the entire plant, expressed per dry weight of the exposed parts, was sixfold higher for the roots than for the exposed stem base. At equal RCs concentrations in both compartments, the exposed stem base and root uptake contributed almost equally to the total shoot RCs concentrations. Reducing potassium supply to the roots not only increased the root RCs uptake but also increased RCs uptake by the stem base. This study was the first to experimentally demonstrate active and internally regulated RCs uptake by the stem base of rice. Scenario calculations for the Fukushima-affected area predict that RCs in irrigation water could be an important source of RCs in rice as indirectly suggested from field data. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
Well balancing of the SWE schemes for moving-water steady flows

NASA Astrophysics Data System (ADS)

Caleffi, Valerio; Valiani, Alessandro

2017-08-01

In this work, the exact reproduction of a moving-water steady flow via the numerical solution of the one-dimensional shallow water equations is studied. A new scheme based on a modified version of the HLLEM approximate Riemann solver (Dumbser and Balsara (2016) [18]) that exactly preserves the total head and the discharge in the simulation of smooth steady flows and that correctly dissipates mechanical energy in the presence of hydraulic jumps is presented. This model is compared with a selected set of schemes from the literature, including models that exactly preserve quiescent flows and models that exactly preserve moving-water steady flows. The comparison highlights the strengths and weaknesses of the different approaches. In particular, the results show that the increase in accuracy in the steady state reproduction is counterbalanced by a reduced robustness and numerical efficiency of the models. Some solutions to reduce these drawbacks, at the cost of increased algorithm complexity, are presented.
[Rice water with and without electrolytes in diarrhea with a high stool output].

PubMed

Mota-Hernández, F; Posadas-Tello, N M; Rodríguez-Leyva, G

1993-12-01

The objective of the study was to determine the efficacy and safety of two rice-based oral rehydration solutions, with and without added electrolyte in children presenting acute diarrheal dehydration with high stool output (> 10 mL/kg/h) during a two-hour rehydration period. Twenty-two patients of one to 18 months old were recruited and randomly distributed into two groups: group A received the rice-based solution without electrolytes, and group B received the rice-based solution with electrolytes. A stool output diminishing was observed in both groups and rehydration was achieved in 4.0 +/- 0.9 hours in 21 patients from group A and in 4.6 +/- 0.9 hours in 13 patients group group B. There was not a statistically significant difference between the groups regarding the laboratory results. The rice-based oral rehydration solution without added electrolytes was useful for rehydration of children presenting high stool output, after administering the WHO/ORS recommended formula during a two-hour period.
Mesoporous Silica Gel-Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler.

PubMed

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y; Huo, Fengwei

2015-11-23

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4-30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores.
Mesoporous Silica Gel–Based Mixed Matrix Membranes for Improving Mass Transfer in Forward Osmosis: Effect of Pore Size of Filler

PubMed Central

Lee, Jian-Yuan; Wang, Yining; Tang, Chuyang Y.; Huo, Fengwei

2015-01-01

The efficiency of forward osmosis (FO) process is generally limited by the internal concentration polarization (ICP) of solutes inside its porous substrate. In this study, mesoporous silica gel (SG) with nominal pore size ranging from 4–30 nm was used as fillers to prepare SG-based mixed matrix substrates. The resulting mixed matrix membranes had significantly reduced structural parameter and enhanced membrane water permeability as a result of the improved surface porosity of the substrates. An optimal filler pore size of ~9 nm was observed. This is in direct contrast to the case of thin film nanocomposite membranes, where microporous nanoparticle fillers are loaded to the membrane rejection layer and are designed in such a way that these fillers are able to retain solutes while allowing water to permeate through them. In the current study, the mesoporous fillers are designed as channels to both water and solute molecules. FO performance was enhanced at increasing filler pore size up to 9 nm due to the lower hydraulic resistance of the fillers. Nevertheless, further increasing filler pore size to 30 nm was accompanied with reduced FO efficiency, which can be attributed to the intrusion of polymer dope into the filler pores. PMID:26592565
Transdermal delivery of diclofenac using water-in-oil microemulsion: formulation and mechanistic approach of drug skin permeation.

PubMed

Thakkar, Priyanka J; Madan, Parshotam; Lin, Senshang

2014-05-01

The objective of the present investigation was to enhance skin permeation of diclofenac using water-in-oil microemulsion and to elucidate its skin permeation mechanism. The w/o microemulsion formulations were selected based on constructed pseudoternary phase diagrams depending on water solubilization capacity and thermodynamic stability. These formulations were also subjected to physical characterization based on droplet size, viscosity, pH and conductivity. Permeation of diclofenac across rat skin using side-by-side permeation cells from selected w/o microemulsion formulations were evaluated and compared with control formulations. The selected w/o microemulsion formulations were thermodynamically stable, and incorporation of diclofenac sodium into microemulsion did not affect the phase behavior of system. All microemulsion formulations had very low viscosity (11-17 cps) and droplet size range of 30-160 nm. Microemulsion formulations exhibited statistically significant increase in diclofenac permeation compared to oily solution, aqueous solution and oil-Smix solution. Higher skin permeation of diclofenac was observed with low Smix concentration and smaller droplet size. Increase in diclofenac loading in aqueous phase decreased the partition of diclofenac. Diclofenac from the oil phase of microemulsion could directly partition into skin, while diclofenac from the aqueous droplets was carried through skin by carrier effect.

Extemporaneous compounding of medicated ointments.

PubMed

Nagel, Karen; Ali, Fatima; Al-Khudari, Sarah; Khan, Ayesha; Patel, Khushbu; Patel, Nikunj; Desai, Archana

2010-01-01

Topical preparations represent a large percentage of compounded prescriptions, particularly in the area of dermatology. Properties of ointment bases vary greatly, and active ingredients are frequently added as aqueous or alcoholic solutions. Currently, there are no quantitative guidelines stating the various water and alcohol absorption capacity of different bases. A short experiment was designed to quantitate the amount of water or alcohol that could be absorbed by a series of ointment bases of varying types. Our findings may be used to assist compounding pharmacists in deciding what base is most suitable to use when considering the amount of water, alcohol, or any similar solvent needed to compound the preparation. A general overview of issues related to topical medication compounding is also provided in this article.
An Improved Neutron Transport Algorithm for Space Radiation

NASA Technical Reports Server (NTRS)

Heinbockel, John H.; Clowdsley, Martha S.; Wilson, John W.

2000-01-01

A low-energy neutron transport algorithm for use in space radiation protection is developed. The algorithm is based upon a multigroup analysis of the straight-ahead Boltzmann equation by using a mean value theorem for integrals. This analysis is accomplished by solving a realistic but simplified neutron transport test problem. The test problem is analyzed by using numerical and analytical procedures to obtain an accurate solution within specified error bounds. Results from the test problem are then used for determining mean values associated with rescattering terms that are associated with a multigroup solution of the straight-ahead Boltzmann equation. The algorithm is then coupled to the Langley HZETRN code through the evaporation source term. Evaluation of the neutron fluence generated by the solar particle event of February 23, 1956, for a water and an aluminum-water shield-target configuration is then compared with LAHET and MCNPX Monte Carlo code calculations for the same shield-target configuration. The algorithm developed showed a great improvement in results over the unmodified HZETRN solution. In addition, a two-directional solution of the evaporation source showed even further improvement of the fluence near the front of the water target where diffusion from the front surface is important.
Definition and solution of a stochastic inverse problem for the Manning’s n parameter field in hydrodynamic models

DOE PAGES

Butler, Troy; Graham, L.; Estep, D.; ...

2015-02-03

The uncertainty in spatially heterogeneous Manning’s n fields is quantified using a novel formulation and numerical solution of stochastic inverse problems for physics-based models. The uncertainty is quantified in terms of a probability measure and the physics-based model considered here is the state-of-the-art ADCIRC model although the presented methodology applies to other hydrodynamic models. An accessible overview of the formulation and solution of the stochastic inverse problem in a mathematically rigorous framework based on measure theory is presented in this paper. Technical details that arise in practice by applying the framework to determine the Manning’s n parameter field in amore » shallow water equation model used for coastal hydrodynamics are presented and an efficient computational algorithm and open source software package are developed. A new notion of “condition” for the stochastic inverse problem is defined and analyzed as it relates to the computation of probabilities. Finally, this notion of condition is investigated to determine effective output quantities of interest of maximum water elevations to use for the inverse problem for the Manning’s n parameter and the effect on model predictions is analyzed.« less
Charge Behaviors around Oxide Device/Pseudo-Physiological Solution Interface with Molecular Dynamic Simulations

NASA Astrophysics Data System (ADS)

Maekawa, Yuki; Shibuta, Yasushi; Sakata, Toshiya

2013-12-01

In this study, we investigated the charge behaviors of ions and water molecules at the oxide device/pseudo-physiological solution interface by use of molecular dynamics (MD) simulations because the detection principle of semiconductor-based biosensors is based on the detection of charge density changes at the oxide sensing surface in physiological environments. In particular, we designed an alpha-quartz (100) surface with some charges corresponding to pH=5.5 so that the ionic behaviors for 500 mM each of Na+ and Cl- around the interface were calculated under the surface condition with charges, considering a real system. As a result of the simulation, we defined the region of Debye length from the calculated potential distribution, in which some parameters such as diffusion coefficient and the vibration of water molecules around the interface differed from those of the bulk solution. The elucidation of the solid/liquid interfacial behaviors by the simulation technique should deepen our understanding of the detection principle of semiconductor-based biosensors and will give guidelines for the design of a bio-interface in the field of biosensing technology, because they cannot be demonstrated experimentally.
Observed changes in the Earth's dynamic oblateness from GRACE data and geophysical models.

PubMed

Sun, Y; Ditmar, P; Riva, R

A new methodology is proposed to estimate changes in the Earth's dynamic oblateness ([Formula: see text] or equivalently, [Formula: see text]) on a monthly basis. The algorithm uses monthly Gravity Recovery and Climate Experiment (GRACE) gravity solutions, an ocean bottom pressure model and a glacial isostatic adjustment (GIA) model. The resulting time series agree remarkably well with a solution based on satellite laser ranging (SLR) data. Seasonal variations of the obtained time series show little sensitivity to the choice of GRACE solutions. Reducing signal leakage in coastal areas when dealing with GRACE data and accounting for self-attraction and loading effects when dealing with water redistribution in the ocean is crucial in achieving close agreement with the SLR-based solution in terms of de-trended solutions. The obtained trend estimates, on the other hand, may be less accurate due to their dependence on the GIA models, which still carry large uncertainties.
Osmotic water transport in aquaporins: evidence for a stochastic mechanism

PubMed Central

Zeuthen, Thomas; Alsterfjord, Magnus; Beitz, Eric; MacAulay, Nanna

2013-01-01

We test a novel, stochastic model of osmotic water transport in aquaporins. A solute molecule present at the pore mouth can either be reflected or permeate the pore. We assume that only reflected solute molecules induce osmotic transport of water through the pore, while permeating solute molecules give rise to no water transport. Accordingly, the rate of water transport is proportional to the reflection coefficient σ, while the solute permeability, PS, is proportional to 1 –σ. The model was tested in aquaporins heterologously expressed in Xenopus oocytes. A variety of aquaporin channel sizes and geometries were obtained with the two aquaporins AQP1 and AQP9 and mutant versions of these. Osmotic water transport was generated by adding 20 mm of a range of different-sized osmolytes to the outer solution. The osmotic water permeability and the reflection coefficient were measured optically at high resolution and compared to the solute permeability obtained from short-term uptake of radio-labelled solute under isotonic conditions. For each type of aquaporin there was a linear relationship between solute permeability and reflection coefficient, in accordance with the model. We found no evidence for coupling between water and solute fluxes in the pore. In confirmation of molecular dynamic simulations, we conclude that the magnitude of the osmotic water permeability and the reflection coefficient are determined by processes at the arginine selectivity filter located at the outward-facing end of the pore. PMID:23959676
Analysis of temperature time series to estimate direction and magnitude of water fluxes in near-surface sediments

NASA Astrophysics Data System (ADS)

Munz, Matthias; Oswald, Sascha E.; Schmidt, Christian

2017-04-01

The application of heat as a hydrological tracer has become a standard method for quantifying water fluxes between groundwater and surface water. Typically, time series of temperatures in the surface water and in the sediment are observed and are subsequently evaluated by a vertical 1D representation of heat transport by advection and dispersion. Several analytical solutions as well as their implementation into user-friendly software exist in order to estimate water fluxes from the observed temperatures. The underlying assumption of a stationary, one-dimensional vertical flow field is frequently violated in natural systems. Here subsurface water flow often has a significant horizontal component. We developed a methodology for identifying the geometry of the subsurface flow field based on the variations of diurnal temperature amplitudes with depths. For instance: Purely vertical heat transport is characterized by an exponential decline of temperature amplitudes with increasing depth. Pure horizontal flow would be indicated by a constant, depth independent vertical amplitude profile. The decline of temperature amplitudes with depths could be fitted by polynomials of different order whereby the best fit was defined by the highest Akaike Information Criterion. The stepwise model optimization and selection, evaluating the shape of vertical amplitude ratio profiles was used to determine the predominant subsurface flow field, which could be systematically categorized in purely vertical and horizontal (hyporheic, parafluvial) components. Analytical solutions to estimate water fluxes from the observed temperatures are restricted to specific boundary conditions such as a sinusoidal upper temperature boundary. In contrast numerical solutions offer higher flexibility and can handle temperature data which is characterized by irregular variations such as storm-event induced temperature changes and thus cannot readily be incorporated in analytical solutions. There are several numerical models that simulate heat transport in porous media (e.g. VS2DH, HydroGeoSphere, FEFLOW) but there can be a steep learning curve to the modelling frameworks and may therefore not readily accessible to routinely infer water fluxes between groundwater and surface water. We developed a user-friendly, straightforeward to use software to estimate water FLUXes Based On Temperatures- FLUX-BOT. FLUX-BOT is a numerical code written in MATLAB that calculates time variable vertical water fluxes in saturated sediments based on the inversion of measured temperature time series observed at multiple depths. It applies a cell-centered Crank-Nicolson implicit finite difference scheme to solve the one-dimensional heat advection-conduction equation (FLUX-BOT can be downloaded from the following web site: https://bitbucket.org/flux-bot/flux-bot). We provide applications of FLUX-BOT to generic as well as to measured temperature data to demonstrate its performance. Both, the empirical analysis of temperature amplitudes as well as the numerical inversion of measured temperature time series to estimate the vertical magnitude of water fluxes extent the suite of current heat tracing methods and may provide insight into temperature data from an additional perspective.
On the Control of Solute Mass Fluxes and Concentrations Below Fields Irrigated With Low-Quality Water: A Numerical Study

NASA Astrophysics Data System (ADS)

Russo, David

2017-11-01

The main goal of this study was to test the capability of irrigation water-based and soil-based approaches to control nitrate and chloride mass fluxes and concentrations below the root zone of agricultural fields irrigated with treated waste water (TWW). Using numerical simulations of flow and transport in relatively a fine-textured, unsaturated, spatially heterogeneous, flow domain, scenarios examined include: (i) irrigating with TWW only (REF); (ii) irrigation water is substituted between TWW and desalinized water (ADW); (iii) soil includes a capillary barrier (CB) and irrigating with TWW only (CB + TWW); and (iv) combination of (ii) and a CB (CB + ADW). Considering groundwater quality protection, plausible goals are: (i) to minimize solute discharges leaving the root zone, and, (ii) to maximize the probability that solute concentrations leaving the root zone will not exceed a prescribed, critical value. Results of the analyses suggest that in the case of a seasonal crop (a corn field) subject to irrigations only, with respect to the first goal, the CB + TWW and CB + ADW scenarios provide similar, excellent results, better than the ADW scenario; with respect to the second goal, however, the CB + ADW scenario gave substantially better results than the CB + TWW scenario. In the case a multiyear, perennial crop (a citrus orchard), subject to a sequence of irrigation and rainfall periods, for both solutes, and, particularly, nitrate, with respect to the two goals, both the ADW and CB + ADW scenarios perform better than the CB + TWW scenario. As compared with the REF and CB + TWW scenarios, the ADW and CB + ADW scenarios substantially reduce nitrogen mass fluxes to the groundwater and to the atmosphere, and, essentially, did not reduce nitrogen mass fluxes to the trees. Similar results, even better, were demonstrated for a relatively coarse-textured, spatially heterogeneous soil.
Chemical weathering rates of a soil chronosequence on granitic alluvium: III. Hydrochemical evolution and contemporary solute fluxes and rates

USGS Publications Warehouse

White, A.F.; Schulz, M.S.; Vivit, D.V.; Blum, A.E.; Stonestrom, David A.; Harden, J.W.

2005-01-01

Although long-term changes in solid-state compositions of soil chronosequences have been extensively investigated, this study presents the first detailed description of the concurrent hydrochemical evolution and contemporary weathering rates in such sequences. The most direct linkage between weathering and hydrology over 3 million years of soil development in the Merced chronosequence in Central California relates decreasing permeability and increasing hydrologic heterogeneity to the development of secondary argillic horizons and silica duripans. In a highly permeable, younger soil (40 kyr old), pore water solutes reflect seasonal to decadal-scale variations in rainfall and evapotranspiration (ET). This climate signal is strongly damped in less permeable older soils (250 to 600 kyr old) where solutes increasingly reflect weathering inputs modified by heterogeneous flow. Elemental balances in the soils are described in terms of solid state, exchange and pore water reservoirs and input/output fluxes from precipitation, ET, biomass, solute discharge and weathering. Solute mineral nutrients are strongly dependent on biomass variations as evidenced by an apparent negative K weathering flux reflecting aggradation by grassland plants. The ratios of solute Na to other base cations progressively increase with soil age. Discharge fluxes of Na and Si, when integrated over geologic time, are comparable to solid-state mass losses in the soils, implying similar past weathering conditions. Similarities in solute and sorbed Ca/Mg ratios reflect short-term equilibrium with the exchange reservoir. Long-term consistency in solute ratios, when contrasted against progressive decreases in solid-state Ca/Mg, requires an additional Ca source, probably from dry deposition. Amorphous silica precipitates from thermodynamically-saturated pore waters during periods of high evapotranspiration and result in the formation of duripans in the oldest soils. The degree of feldspar and secondary gibbsite and kaolinite saturation varies both spatially and temporally due to the seasonality of plant-respired CO2 and a decrease in organically complexed Al. In deeper pore waters, K-feldspar is in equilibrium and plagioclase is about an order of magnitude undersaturated. Hydrologic heterogeneity produces a range of weathering gradients that are constrained by solute distributions and matrix and macropore flow regimes. Plagioclase weathering rates, based on precipitation-corrected Na gradients, vary between 3 and 7 ?? 10-16 mol m-2 s-1. These rates are similar to previously determined solid-state rates but are several orders of magnitude slower than for experimental plagioclase dissolution indicating strong inhibitions to natural weathering, partly due to near-equilibrium weathering reactions. Copyright ?? 2005 Elsevier Ltd.
Spectrum of Slow and Super-Slow (Picosecond to Nanosecond) Water Dynamics around Organic and Biological Solutes.

PubMed

Ramakrishnan, Gopakumar; González-Jiménez, Mario; Lapthorn, Adrian J; Wynne, Klaas

2017-07-06

Water dynamics in the solvation shell of solutes plays a very important role in the interaction of biomolecules and in chemical reaction dynamics. However, a selective spectroscopic study of the solvation shell is difficult because of the interference of the solute dynamics. Here we report on the observation of heavily slowed down water dynamics in the solvation shell of different solutes by measuring the low-frequency spectrum of solvation water, free from the contribution of the solute. A slowdown factor of ∼50 is observed even for relatively low concentrations of the solute. We go on to show that the effect can be generalized to different solutes including proteins.
Efficient ensemble system based on the copper binding motif for highly sensitive and selective detection of cyanide ions in 100% aqueous solutions by fluorescent and colorimetric changes.

PubMed

Jung, Kwan Ho; Lee, Keun-Hyeung

2015-09-15

A peptide-based ensemble for the detection of cyanide ions in 100% aqueous solutions was designed on the basis of the copper binding motif. 7-Nitro-2,1,3-benzoxadiazole-labeled tripeptide (NBD-SSH, NBD-SerSerHis) formed the ensemble with Cu(2+), leading to a change in the color of the solution from yellow to orange and a complete decrease of fluorescence emission. The ensemble (NBD-SSH-Cu(2+)) sensitively and selectively detected a low concentration of cyanide ions in 100% aqueous solutions by a colorimetric change as well as a fluorescent change. The addition of cyanide ions instantly removed Cu(2+) from the ensemble (NBD-SSH-Cu(2+)) in 100% aqueous solutions, resulting in a color change of the solution from orange to yellow and a "turn-on" fluorescent response. The detection limits for cyanide ions were lower than the maximum allowable level of cyanide ions in drinking water set by the World Health Organization. The peptide-based ensemble system is expected to be a potential and practical way for the detection of submicromolar concentrations of cyanide ions in 100% aqueous solutions.
Evaluation of Polyuria: The Roles of Solute Loading and Water Diuresis.

PubMed

Bhasin, Bhavna; Velez, Juan Carlos Q

2016-03-01

Polyuria, defined as daily urine output in excess of 3.0 to 3.5L/d, can occur due to solute or water diuresis. Solute-induced polyuria can be seen in hospitalized patients after a high solute load from exogenous protein administration or following relief of urinary obstruction. Similar clinical scenarios are rarely encountered in the outpatient setting. We describe a case of polyuria due to high solute ingestion and excessive water intake leading to a mixed picture of solute and water diuresis. Restriction of the daily solute load and water intake resulted in complete resolution of polyuria. Determination of the daily excreted urinary osmoles may yield important clues to the cause of polyuria and should be included in the routine workup of polyuria. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.
Water vapor diffusion membranes, 2

NASA Technical Reports Server (NTRS)

Holland, F. F.; Klein, E.; Smith, J. K.; Eyer, C.

1976-01-01

Transport mechanisms were investigated for the three different types of water vapor diffusion membranes. Membranes representing porous wetting and porous nonwetting structures as well as dense diffusive membrane structures were investigated for water permeation rate as a function of: (1) temperature, (2) solids composition in solution, and (3) such hydrodynamic parameters as sweep gas flow rate, solution flow rate and cell geometry. These properties were measured using nitrogen sweep gas to collect the effluent. In addition, the chemical stability to chromic acid-stabilized urine was measured for several of each type of membrane. A technology based on the mechanism of vapor transport was developed, whereby the vapor diffusion rates and relative susceptibility of membranes to fouling and failure could be projected for long-term vapor recovery trials using natural chromic acid-stabilized urine.
Acid-base properties of water-soluble organic matter of forest soils, studied by the pK-spectroscopy method.

PubMed

Shamrikova, E V; Ryazanov, M A; Vanchikova, E V

2006-11-01

Using the potentiometric titration and pK spectroscopy method, acid-base properties of water-soluble organic matter of forest soils have been studied. Five acidic classes composed of different substances with pK(a) values around 3.6; 4.8; 6.7; 8.7 and 9.7 have been identified. Testing the properties of soluble soil fraction, it is to be taken into account that when it is isolated from non-soluble soil matter, some water-soluble substances remain in soil and do not pass into the solution. Most firmly adsorbed in soil are water-soluble components with pK(a) 9.6-9.8.
Recent advances in ruthenium complex-based light-driven water oxidation catalysts.

PubMed

Xue, Long-Xin; Meng, Ting-Ting; Yang, Wei; Wang, Ke-Zhi

2015-11-01

The light driven splitting of water is one of the most attractive approaches for direct conversion of solar energy into chemical energy in the future. Ruthenium complexes as the water oxidation catalysts (WOCs) and light sensitizers have attracted increasing attention, and have made a great progress. This mini-review highlights recent progress on ruthenium complex-based photochemical and photoelectrochemical water oxidation catalysts. The recent representative examples of these ruthenium complexes that are in homogeneous solution or immobilized on solid electrodes, are surveyed. In particular, special attention has been paid on the supramolecular dyads with photosensitizer and WOC being covalently hold together, and grafted onto the solid electrode. Copyright © 2015 Elsevier B.V. All rights reserved.
Effect of gamma radiation on the physico-chemical properties of alginate-based films and beads

NASA Astrophysics Data System (ADS)

Huq, Tanzina; Khan, Avik; Dussault, Dominic; Salmieri, Stephane; Khan, Ruhul A.; Lacroix, Monique

2012-08-01

Alginate solution (3%, w/v) was prepared using deionized water from its powder. Then the solution was exposed to gamma radiation (0.1-25 kGy). The alginate films were prepared by solution casting. It was found that gamma radiation has strong effect on alginate solution. At low doses, mechanical strength of the alginate films improved but after 5 kGy dose, the strength started to decrease. The mechanism of alginate radiolysis in aqueous solution is discussed. Film formation was not possible from alginate solution at doses >5 kGy. The mechanical properties such as puncture strength (PS), puncture deformation (PD), viscoelasticity (Y) coefficient of the un-irradiated films were investigated. The values of PS, PD and Y coefficient of the films were 333 N/mm, 3.20 mm and 27%, respectively. Alginate beads were prepared from 3% alginate solution (w/v) by ionotropic gelation method in 5% CaCl2 solution. The rate of gel swelling improved in irradiated alginate-based beads at low doses (up to 0.5 kGy).
Application of membrane processes to alcohol-water separation: Improving the energy efficiency of biofuel production

EPA Science Inventory

Pervaporation • Membrane-based separation process • Not filtration Separation based on solution-diffusion transport through non-porous or “molecularly-porous” membrane Permeate is a vapor • Permeate contains only volatile compounds • Able to separate mixtures of mis...
Kinetic control of block copolymer self-assembly into multicompartment and novel geometry nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Yingchao; Wang, Xiaojun; Zhang, Ke; Wooley, Karen; Mays, Jimmy; Percec, Virgil; Pochan, Darrin

2012-02-01

Micelles with the segregation of hydrophobic blocks trapped in the same nanoparticle core have been produced through co-self-assembly of two block copolymers in THF/water dilute solution. The dissolution of two block copolymer sharing the same polyacrylic acid PAA blocks in THF undergoes consequent aggregation and phase separation through either slow water titration or quick water addition that triggers the micellar formation. The combination and comparison of the two water addition kinetic pathways are the keys of forming multicompartment structures at high water content. Importantly, the addition of organic diamine provides for acid-base complexation with the PAA side chains which, in turn, plays the key role of trapping unlike hydrophobic blocks from different block copolymers into one nanoparticle core. The kinetic control of solution assembly can be applied to other molecular systems such as dendrimers as well as other block copolymer molecules. Transmission electron microscopy, cryogenic transmission electron microscopy, light scattering have been applied to characterize the micelle structures.
Gravity flow and solute dispersion in variably saturated sand

NASA Astrophysics Data System (ADS)

Kumahor, Samuel K.; de Rooij, Gerrit H.; Vogel, Hans-Joerg

2014-05-01

Solute dispersion in porous media depends on the structure of the velocity field at the pore scale. Hence, dispersion is expected to change with water content and with mean flow velocity. We performed laboratory experiments using a column of repacked fine-grained quartz sand (0.1-0.3 mm grain size) with a porous plate at the bottom to controle the water potential at the lower boundary. We established gravity flow conditions - i.e. constant matric potential and water content throughout the column - for a number of different irrigation rates. We measured breakthrough curves during unit gradient flow for an inert tracer which could be described by the convection-dispersion equation. As the soil water content decreased we observed an initially gradual increase in dispersivity followed by an abrupt increase below a threshold water content (0.19) and pressure head (-38 hPa). This phenomena can be explained by the geometry of phase distribution which was simulated based on Xray-CT images of the porous structure.
Optimal integrated management of groundwater resources and irrigated agriculture in arid coastal regions

NASA Astrophysics Data System (ADS)

Grundmann, J.; Schütze, N.; Heck, V.

2014-09-01

Groundwater systems in arid coastal regions are particularly at risk due to limited potential for groundwater replenishment and increasing water demand, caused by a continuously growing population. For ensuring a sustainable management of those regions, we developed a new simulation-based integrated water management system. The management system unites process modelling with artificial intelligence tools and evolutionary optimisation techniques for managing both water quality and water quantity of a strongly coupled groundwater-agriculture system. Due to the large number of decision variables, a decomposition approach is applied to separate the original large optimisation problem into smaller, independent optimisation problems which finally allow for faster and more reliable solutions. It consists of an analytical inner optimisation loop to achieve a most profitable agricultural production for a given amount of water and an outer simulation-based optimisation loop to find the optimal groundwater abstraction pattern. Thereby, the behaviour of farms is described by crop-water-production functions and the aquifer response, including the seawater interface, is simulated by an artificial neural network. The methodology is applied exemplarily for the south Batinah re-gion/Oman, which is affected by saltwater intrusion into a coastal aquifer system due to excessive groundwater withdrawal for irrigated agriculture. Due to contradicting objectives like profit-oriented agriculture vs aquifer sustainability, a multi-objective optimisation is performed which can provide sustainable solutions for water and agricultural management over long-term periods at farm and regional scales in respect of water resources, environment, and socio-economic development.

Serving California's Science and Governance Needs through Crisis-driven Collaborations

NASA Astrophysics Data System (ADS)

Bernacchi, L.

2015-12-01

Due to its magnitude, the ongoing drought in California (USA) serves as an experimental space for innovative resource management and will define responses to predicted widespread drought. Due to the magnitude of its effect on humans and natural ecosystems and the water resources on which they depend, governmental programs are granting support to scientifically-valid, locally-produced solutions to water scarcity. Concurrently, University of California Water (UC Water) Security and Sustainability Research Initiative is focused on strategic research to build the knowledge base for better water resources management. This paper examines how a team of transdisciplinary scientists are engaged in water governance and information, providing examples of actionable research successfully implemented by decision makers. From a sociology of science perspective, UC Water scientists were interviewed about their engagement practices with California water decision makers. Their "co-production of knowledge" relationships produce effective responses to climatic, landcover and population changes by expanding from singularly information-based, unidirectional communication to governance-relevant, co-constructed knowledge and wisdom. This is accomplished by serving on decision making organizational boards and developing information in a productive format. The perceived crisis of California's drought is an important impetus in cross-sector collaborations, and in combination with governance and institution parameters, defines the inquiry and decision space. We conclude by describing a process of clear problem-solution definition made possible through transparent communication, salient and credible information, and relevant tools and techniques for interpreting scientific findings.
Electronic properties of semiconductor-water interfaces: Predictions from ab-initio molecular dynamics and many-body perturbation theory

NASA Astrophysics Data System (ADS)

Pham, Tuan Anh

2015-03-01

Photoelectrochemical cells offer a promising avenue for hydrogen production from water and sunlight. The efficiency of these devices depends on the electronic structure of the interface between the photoelectrode and liquid water, including the alignment between the semiconductor band edges and the water redox potential. In this talk, we will present the results of first principles calculations of semiconductor-water interfaces that are obtained with a combination of density functional theory (DFT)-based molecular dynamics simulations and many-body perturbation theory (MBPT). First, we will discuss the development of an MBPT approach that is aimed at improving the efficiency and accuracy of existing methodologies while still being applicable to complex heterogeneous interfaces consisting of hundreds of atoms. We will then present studies of the electronic structure of liquid water and aqueous solutions using MBPT, which represent an essential step in establishing a quantitative framework for computing the energy alignment at semiconductor-water interfaces. Finally, using a combination of DFT-based molecular dynamics simulations and MBPT, we will describe the relationship between interfacial structure, electronic properties of semiconductors and their reactivity in aqueous solutions through a number of examples, including functionalized Si surfaces and GaP/InP surfaces in contact with liquid water. T.A.P was supported by the U.S. Department of Energy at the Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and by the Lawrence Fellowship Program.
Biosorbents prepared from wood particles treated with anionic polymer and iron salt: Effect of particle size on phosphate adsorption

Treesearch

Thomas L. Eberhardt; Soo-Hong Min

2008-01-01

Biomass-based adsorbents have been widely studied as a cost-effective and environmentally-benign means to remove pollutants and nutrients from water. A two-stage treatment of aspen wood particles with solutions of carboxymethyl cellulose (CMC) and ferrous chloride afforded a biosorbent that was effective in removing phosphate from test solutions. FTIR spectroscopy of...
Room temperature synthesis of protonated layered titanate sheets using peroxo titanium carbonate complex solution.

PubMed

Sutradhar, Narottam; Sinhamahapatra, Apurba; Pahari, Sandip Kumar; Bajaj, Hari C; Panda, Asit Baran

2011-07-21

We report the synthesis of peroxo titanium carbonate complex solution as a novel water-soluble precursor for the direct synthesis of layered protonated titanate at room temperature. The synthesized titanates showed excellent removal capacity for Pb(2+) and methylene blue. Based on experimental observations, a probable mechanism for the formation of protonated layered dititanate sheets is also discussed.
Hammerhead ribozyme activity and oligonucleotide duplex stability in mixed solutions of water and organic compounds

PubMed Central

Nakano, Shu-ichi; Kitagawa, Yuichi; Miyoshi, Daisuke; Sugimoto, Naoki

2014-01-01

Nucleic acids are useful for biomedical targeting and sensing applications in which the molecular environment is different from that of a dilute aqueous solution. In this study, the influence of various types of mixed solutions of water and water-soluble organic compounds on RNA was investigated by measuring the catalytic activity of the hammerhead ribozyme and the thermodynamic stability of an oligonucleotide duplex. The compounds with a net neutral charge, such as poly(ethylene glycol), small primary alcohols, amide compounds, and aprotic solvent molecules, added at high concentrations changed the ribozyme-catalyzed RNA cleavage rate, with the magnitude of the effect dependent on the NaCl concentration. These compounds also changed the thermodynamic stability of RNA base pairs of an oligonucleotide duplex and its dependence on the NaCl concentration. Specific interactions with RNA molecules and reduced water activity could account for the inhibiting effects on the ribozyme catalysis and destabilizing effects on the duplex stability. The salt concentration dependence data correlated with the dielectric constant, but not with water activity, viscosity, and the size of organic compounds. This observation suggests the significance of the dielectric constant effects on the RNA reactions under molecular crowding conditions created by organic compounds. PMID:25161873
Direct spectrophotometric method for analysis of food supplements containing synthetic polyhydroquinones

NASA Astrophysics Data System (ADS)

Vasilevsky, A. M.; Konoplev, G. A.; Stepanova, O. S.; Toropov, D. K.; Zagorsky, A. L.

2016-04-01

A novel direct spectrophotometric method for quantitative determination of Oxiphore® drug substance (synthetic polyhydroquinone complex) in food supplements is developed. Absorption spectra of Oxiphore® water solutions in the ultraviolet region are presented. Samples preparation procedures and mathematical methods of spectra post-analytical procession are discussed. Basic characteristics of the automatic CCD-based UV spectrophotometer and special software implementing the developed method are described. The results of the trials of the developed method and software are analyzed: the error of determination for Oxiphore® concentration in water solutions of the isolated substance and singlecomponent food supplements did not exceed 15% (average error was 7…10%).
Evaluation of protein-protein docking model structures using all-atom molecular dynamics simulations combined with the solution theory in the energy representation

NASA Astrophysics Data System (ADS)

Takemura, Kazuhiro; Guo, Hao; Sakuraba, Shun; Matubayasi, Nobuyuki; Kitao, Akio

2012-12-01

We propose a method to evaluate binding free energy differences among distinct protein-protein complex model structures through all-atom molecular dynamics simulations in explicit water using the solution theory in the energy representation. Complex model structures are generated from a pair of monomeric structures using the rigid-body docking program ZDOCK. After structure refinement by side chain optimization and all-atom molecular dynamics simulations in explicit water, complex models are evaluated based on the sum of their conformational and solvation free energies, the latter calculated from the energy distribution functions obtained from relatively short molecular dynamics simulations of the complex in water and of pure water based on the solution theory in the energy representation. We examined protein-protein complex model structures of two protein-protein complex systems, bovine trypsin/CMTI-1 squash inhibitor (PDB ID: 1PPE) and RNase SA/barstar (PDB ID: 1AY7), for which both complex and monomer structures were determined experimentally. For each system, we calculated the energies for the crystal complex structure and twelve generated model structures including the model most similar to the crystal structure and very different from it. In both systems, the sum of the conformational and solvation free energies tended to be lower for the structure similar to the crystal. We concluded that our energy calculation method is useful for selecting low energy complex models similar to the crystal structure from among a set of generated models.
Evaluation of protein-protein docking model structures using all-atom molecular dynamics simulations combined with the solution theory in the energy representation.

PubMed

Takemura, Kazuhiro; Guo, Hao; Sakuraba, Shun; Matubayasi, Nobuyuki; Kitao, Akio

2012-12-07

We propose a method to evaluate binding free energy differences among distinct protein-protein complex model structures through all-atom molecular dynamics simulations in explicit water using the solution theory in the energy representation. Complex model structures are generated from a pair of monomeric structures using the rigid-body docking program ZDOCK. After structure refinement by side chain optimization and all-atom molecular dynamics simulations in explicit water, complex models are evaluated based on the sum of their conformational and solvation free energies, the latter calculated from the energy distribution functions obtained from relatively short molecular dynamics simulations of the complex in water and of pure water based on the solution theory in the energy representation. We examined protein-protein complex model structures of two protein-protein complex systems, bovine trypsin/CMTI-1 squash inhibitor (PDB ID: 1PPE) and RNase SA/barstar (PDB ID: 1AY7), for which both complex and monomer structures were determined experimentally. For each system, we calculated the energies for the crystal complex structure and twelve generated model structures including the model most similar to the crystal structure and very different from it. In both systems, the sum of the conformational and solvation free energies tended to be lower for the structure similar to the crystal. We concluded that our energy calculation method is useful for selecting low energy complex models similar to the crystal structure from among a set of generated models.
Study of Heat Transfer Characteristics of Nanofluids in an Automotive Radiator

NASA Astrophysics Data System (ADS)

Harsh, R.; Srivastav, Hitish; Balakrishnan, Prabhat; Saini, Vivek; Senthil Kumar, D.; Rajni, K. S.; Thirumalini, S.

2018-02-01

This paper presents an experimental study on heat transfer using nanofluid as coolants in engines. Previous studies shows that Al2O3 is found to be more effective in heat transfer due to its high conductive property which is found to increase with concentration. Particles having diameter in the range 10-3 to 10-6 m have low thermal conductivities and cause clogging in the flow section along with significant friction and are highly unstable in solution. Nanoparticles on the other hand are easily dispersed and cause minimal clogging or friction in the flow. In the present work, ethylene glycol-water solution is taken as a base fluid for nanoparticle dispersion. The ratio of water to ethylene glycol used is 80:20 and it has been noted out that heat conduction improved with increasing fraction of ethylene glycol. The experiments were conducted with flow rate of 4,5,6 and 7 L/min and the air flow rate inside the duct was kept constant at 4.9 m/s. The temperature of water in the reservoir is kept at 70°C. The nanoparticles used in this experiment are Cu and TiO2 having particle size less than 80nm. Result shows that there is an improvement of 24.5% in the overall heat transfer coefficient and there was also an increase of 13.9% in the heat transfer rate compared to the base fluid (80:20 Water: EG solution).
Comparison of nickel release in solutions used for the identification of water-soluble nickel exposures and in synthetic lung fluids.

PubMed

Oller, Adriana R; Cappellini, Danielle; Henderson, Rayetta G; Bates, Hudson K

2009-04-01

Chemical speciation of workplace nickel exposures is critical because nickel-containing substances often differ in toxicological properties. Exposure matrices based on leaching methods have been used to ascertain which chemical forms of nickel are primarily associated with adverse respiratory effects after inhalation. Misjudgments in the relative proportion of each of the main fractions of nickel in workplace exposures could translate into possible misattributions of risk to the various forms of nickel. This preliminary study looked at the efficiency of the first step of the Zatka leaching method for accurately assessing the 'water-soluble' fraction of several substances present in nickel production operations, compared to leaching in synthetic lung fluid. The present results demonstrate that for nickel sulfate or chloride, the current Zatka solution is adequate to assess the 'water-soluble' fraction. However, when sparingly water-soluble compounds like nickel carbonates or water-insoluble substances like nickel subsulfide and fine metallic nickel powders are present, the first step of the Zatka method can greatly over estimate the amount of nickel that could be released in pure water. In contrast, the releases of nickel from nickel carbonate, nickel subsulfide, and nickel metal powders in pure water are consistent with their releases in synthetic lung fluid, indicating that deionized water is a better leaching solution to estimate the biologically relevant 'water-soluble' nickel fraction of workplace exposures. Exposure matrices relying mostly on the Zatka speciation method to estimate the main forms of nickel need to be re-evaluated to account for any possible misattributions of risk.
Miniaturised enzymatic conductometric biosensor with Nafion membrane for the direct determination of formaldehyde in water samples.

PubMed

Nguyen-Boisse, Thanh-Thuy; Saulnier, Joëlle; Jaffrezic-Renault, Nicole; Lagarde, Florence

2014-02-01

A new conductometric enzyme-based biosensor was developed for the determination of formaldehyde (FA) in aqueous solutions. The biosensor was prepared by cross-linking formaldehyde dehydrogenase from Pseudomonas putida with bovine serum albumin in saturated glutaraldehyde vapours (GA) at the surface of interdigitated gold microelectrodes. Nicotinamide adenine dinucleotide cofactor (NAD(+)) was added in solution at each measurement to maintain enzyme activity. Addition of a Nafion layer over the enzyme modified electrode resulted in a significant increase of biosensor signal due to enhanced accumulation of protons generated by enzymatic reaction at the electrode surface. Different parameters affecting enzyme activity or playing a role in ionic transfer through the Nafion membrane were optimised. In optimal conditions (0.045 mg enzyme, 30 min exposure to GA, 0.3 μL of a 1% (v/v) Nafion solution deposit, measurement in 5 mM phosphate buffer pH 7 containing 20 μM NAD(+)), the biosensor signal was linear up to 10 mM FA, and the detection limit was 18 μM. Relative standard deviations calculated from five consecutive replicates of FA solutions were lower than 5% in the 1-10 mM range. The biosensor was successfully applied to the determination of FA in spiked water samples (tap water and Rhone river water), with recoveries in the 95-110% range.
Silk Nanospheres and Microspheres from Silk/PVA Blend Films for Drug Delivery

PubMed Central

Wang, Xiaoqin; Yucel, Tuna; Lu, Qiang; Hu, Xiao; Kaplan, David L.

2009-01-01

Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindle-shaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 μm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge, resulting in different drug release profiles. The entire fabrication procedure could be completed within one day. The only chemical used in the preparation except water was PVA, an FDA-approved ingredient in drug formulations. Silk micro- and nanospheres reported have potential as drug delivery carriers in a variety of biomedical applications. PMID:19945157
Long-term impact of integration of household water treatment and hygiene promotion with antenatal services on maternal water treatment and hygiene practices in Malawi.

PubMed

Loharikar, Anagha; Russo, Elizabeth; Sheth, Anandi; Menon, Manoj; Kudzala, Amose; Tauzie, Blessius; Masuku, Humphreys D; Ayers, Tracy; Hoekstra, Robert M; Quick, Robert

2013-02-01

A clinic-based program to integrate antenatal services with distribution of hygiene kits including safe water storage containers, water treatment solution (brand name WaterGuard), soap, and hygiene education, was implemented in Malawi in 2007 and evaluated in 2010. We surveyed 389 participants at baseline in 2007, and found and surveyed 232 (60%) participants to assess water treatment, test stored drinking water for residual chlorine (an objective measure of treatment), and observe handwashing technique at follow-up in 2010. Program participants were more likely to know correct water treatment procedures (67% versus 36%; P < 0.0001), treat drinking water with WaterGuard (24% versus 2%; P < 0.0001), purchase and use WaterGuard (21% versus 1%; P < 0.001), and demonstrate correct handwashing technique (50% versus 21%; P < 0.001) at the three-year follow-up survey than at baseline. This antenatal-clinic-based program may have contributed to sustained water treatment and proper handwashing technique among program participants.
Identification of Multiple Water-Iodide Species in Concentrated NaI Solutions Based on the Raman Bending Vibration of Water.

PubMed

Besemer, Matthieu; Bloemenkamp, Rob; Ariese, Freek; van Manen, Henk-Jan

2016-02-11

The influence of aqueous electrolytes on the water bending vibration was studied with Raman spectroscopy. For all salts investigated (NaI, NaBr, NaCl, and NaSCN), we observed a nonlinear intensity increase of the water bending vibration with increasing concentration. Different lasers and a tunable frequency-doubled optical parametric oscillator system were used to achieve excitation wavelengths between 785 and 374 nm. Focusing on NaI solutions, the relative enhancement of the water bending vibration was found to increase strongly with excitation photon energy, in line with a preresonance effect from the iodide-water charge-transfer transition. We used multivariate curve resolution (MCR) to decompose the measured Raman spectra of NaI solutions into three interconverting spectral components assigned to bulk water and water molecules interacting with one (X···H-O-H···O) and two (X···H-O-H···X) iodide ions (X = I(-)). The Raman spectrum of solid sodium iodide dihydrate supports the assignment of the latter. Using the MCR results, relative Raman scattering cross sections of 4.0 ± 0.6 and 14.0 ± 0.1 were calculated for the mono- and di-iodide species, respectively (compared to that of bulk water set to unity). In addition, it was found that at relatively low concentrations each iodide ion affects the Raman spectrum of roughly 22 surrounding water molecules, indicating that the influence of iodide extends beyond the first solvation shell. Our results demonstrate that the Raman bending vibration of water is a sensitive probe, providing new insights into anion solvation in aqueous environments.
A Water and Energy Community of Practice (WECoP)

NASA Astrophysics Data System (ADS)

Houser, P. R.

2008-12-01

Earth is a unique, living planet due to the abundance and vigorous cycling and replenishing of water throughout the global environment. The water cycle operates on a continuum of time and space scales and exchanges large amounts of energy as water undergoes phase changes and is moved from one part of the Earth system to another. Water is essential to life and is central to society's welfare, progress, and sustainable economic growth. However, global water cycle variability which regulates flood, drought, and disease hazards is being continuously transformed by climate change, erosion, pollution, salinization, and agriculture and civil engineering practices. The most visible manifestation that could be expected from climate warming would be changes in the distribution of precipitation and evaporation, and the exacerbation of extreme hydrologic events, floods and droughts. Technological advances, climate modeling and forecasting improvements and the emergence of earth system science will enable development of solutions for these daunting global water problems, and much of the needed scientific information is already available. A plethora of institutional, policy, management and communication problems have been neglected, which has resulted in significant underutilization of existing scientific information for solving contemporary and anticipated water issues. Effective communication and outreach is the critical task to enable existing science to be used to its full potential, to develop comprehensive solution strategies and to set future research priorities. The missing link is a water-focused Community of Practice (CoP) who has knowledge of both the decision support needs and the cutting-edge research results, and therefore can formulate a broad array of solutions to water problems today and into the future. The concept of a community of practice refers to the process of social learning that occurs when people who have a common interest in some subject or problem collaborate over an extended period to share ideas, find solutions, and build innovations. It refers as well to the stable group that is formed from such regular interactions. A CoP consists of three elements; developing these elements will cultivate the CoP: (1) A shared domain of interest - in this case water, (2) CoP members communicate, share information, engage in joint activities and learn from each other, and (3) Members of the CoP are engaged in a shared practice - developing a shared repertoire of resources, experiences, stories, case studies and tools. The NASA water-cycle solutions network project (WaterNet) mission is to improve our collective ability to routinely interact with and harness the results of scientific research so as to address water assessment, prediction and management challenges. This presentation will detail how WaterNet activities are helping to foster and enable a Water and Energy cycle CoP (WECoP), and how partnerships are cultivating an international Water Cycle Community of Practice, as follows: (1) Demonstration project and case studies. (2) Development of a web-based information portal, for sharing ideas and information. (3) Development of a knowledge base and water information search utility. (4) Fostering partnerships amon: CUAHSI, ESIP, NIDIS, GEOSS, GEWEX, NEWS, NCAR, etc. (5) Developing a newsletters and information guides. (6) Education and outreach activities. (7) Developing community-wide user needs, research capabilities and gap assessments. (8) Development of data integration capabilities. (9) Development of rapid-prototyping, test-bed and benchmarking capabilities. (10) Development and sharing of data, model and decision tool assets.
A reversible conductivity modulation of azobenzene-based ionic liquids in aqueous solutions using UV/vis light.

PubMed

Li, Zhiyong; Yuan, Xiaoqing; Feng, Ying; Chen, Yongkui; Zhao, Yuling; Wang, Huiyong; Xu, Qingli; Wang, Jianji

2018-05-09

Photo-induced conductivity modulation of stimuli-responsive materials is of great importance from the viewpoint of fundamental research and technology. In this work, 5 new kinds of azobenzene-based photo-responsive ionic liquids were synthesized and characterized, and UV/vis light modulation of their conductivity was investigated in an aqueous solution. The factors affecting the conductivity modulation of the photo-responsive fluids, such as photo-isomerization efficiency, photo-regulation aggregation, concentration and chemical structure of the ionic liquids, were examined systematically. It was found that the conductivity of the ionic liquids in water exhibited a significant increase upon UV light irradiation and the ionic liquids with a shorter alkyl spacer in the cation showed a more remarkable photo-induced conductivity enhancement with a maximum increase of 150%. In addition, the solution conductivity was restored (or very close) to the initial value upon an alternative irradiation with visible light. Thus, the solution conductivity can be modulated using alternative irradiation with UV and visible light. Although the reversible photo-isomerization of the azobenzene group under UV/vis irradiation is the origin of the conductivity modulation, the photo-regulated aggregation of the ionic liquid in water is indispensable for the maximum degree of conductivity modulation because UV irradiation can weaken, even break the aggregated cis-isomers of the ionic liquids in an aqueous solution.
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.
Laser-ablative fabrication of nanoparticle inks for 3D inkjetprinting of multifunctional coatings

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Ivanova, A. K.; Khmel'nitskii, R. A.; Klevkov, Yu V.; Kudryashov, S. I.; Mel'nik, N. N.; Nastulyavichus, A. A.; Rudenko, A. A.; Saraeva, I. N.; Smirnov, N. A.; Zayarny, D. A.

2017-12-01

We report the fabrication of multifunctional coatings via inkjet printing using water-based nanoinks in the form of selenium (Se) and gold (Au) nanoparticle (NP) colloids, prepared by laser ablation of solid targets in deionized water or 50%-isopropyl alcohol solution. Nanoparticles and NP-based coatings were deposited onto silver films, magnetronsputtered to silica-glass substrates, and characterized by means of scanning and transmission electron microscopy (SEM, TEM), UV-vis-IR, Raman and energy-dispersive X-ray spectroscopies.
Understanding THz spectra of aqueous solutions: glycine in light and heavy water.

PubMed

Sun, Jian; Niehues, Gudrun; Forbert, Harald; Decka, Dominique; Schwaab, Gerhard; Marx, Dominik; Havenith, Martina

2014-04-02

THz spectroscopy of aqueous solutions has been established as of recently to be a valuable and complementary experimental tool to provide direct insights into the solute-solvent coupling due to hydrogen-bond dynamics involving interfacial water. Despite much experimental progress, understanding THz spectra in terms of molecular motions, akin to mid-infrared spectra, still remains elusive. Here, using the osmoprotectant glycine as a showcase, we demonstrate how this can be achieved by combining THz absorption spectroscopy and ab initio molecular dynamics. The experimental THz spectrum is characterized by broad yet clearly discernible peaks. Based on substantial extensions of available mode-specific decomposition schemes, the experimental spectrum can be reproduced by theory and assigned on an essentially quantitative level. This joint effort reveals an unexpectedly clear picture of the individual contributions of molecular motion to the THz absorption spectrum in terms of distinct modes stemming from intramolecular vibrations, rigid-body-like hindered rotational and translational motion, and specific couplings to interfacial water molecules. The assignment is confirmed by the peak shifts observed in the THz spectrum of deuterated glycine in heavy water, which allow us to separate the distinct modes experimentally.
Visible-light Homogeneous Photocatalytic Conversion of CO2 into CO in Aqueous Solutions with an Iron Catalyst.

PubMed

Rao, Heng; Bonin, Julien; Robert, Marc

2017-11-23

An iron-substituted tetraphenyl porphyrin bearing positively charged trimethylammonio groups at the para position of each phenyl ring catalyzes the photoinduced conversion of CO 2 . This complex is water soluble and acts as a molecular catalyst to selectively reduce CO 2 into CO under visible-light irradiation in aqueous solutions (acetonitrile/water=1:9 v/v) with the assistance of purpurin, a simple organic photosensitizer. CO is produced with a catalytic selectivity of 95 % and turnover number up to 120, illustrating the possibility of photocatalyzing the reduction of CO 2 in aqueous solution by using visible light, a simple organic sensitizer coupled to an amine as a sacrificial electron donor, and an earth-abundant metal-based molecular catalyst. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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