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Water Systems (water + system)
Kinds of Water Systems Selected AbstractsRadical Reduction of Epoxides Using a Titanocene(III)/Water System: Synthesis of ,-Deuterated Alcohols and Their Use as Internal Standards in Food AnalysisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2010Tania Jiménez Abstract We describe a comprehensive study into the Cp2TiCl-mediated reductive epoxide ring opening using either water as a hydrogen source or deuterium oxide as a deuterium source. The remarkable chemical profile of this reaction allows access to alcohols with anti-Markovnikov regiochemistry from different epoxides. The use of D2O as a deuterium source leads to an efficient synthesis of ,-deuterated alcohols, including a deuterated sample of tyrosol, a bioactive compound contained in the leaves of the olive, which was successfully applied as an internal standard in food analysis. [source] Solvatochromic Analysis of Partition Coefficients in the o -Nitrophenyl Octyl Ether (o -NPOE)/Water SystemHELVETICA CHIMICA ACTA, Issue 11 2003Xiangli Liu The objective of this study was to unravel the structural properties responsible for the partitioning of solutes in o -nitrophenyl octyl ether (o -NPOE)/H2O, a new solvent system for the determination of the partition coefficients of ions. A set of 88 compounds (including drugs) was selected to allow a regular and broad distribution of property spaces. Partition coefficients in o -NPOE/H2O (log,Pnpoe) were measured by the shake-flask or the potentiometric method. Linear solvation free-energy relationship (LSER) analyses showed that Van der Waals volume, H-bond-acceptor basicity, and H-bond-donor acidity are the three molecular descriptors of solutes determining their log,Pnpoe values. The partitioning mechanism of the investigated compounds in o -NPOE/H2O is controlled by the same structural properties as it is in 1,2-dichloroethane (DCE)/H2O. ,log,Poct,npoe Values (difference between log,Poct and log,Pnpoe) express mainly dipolarity/polarizability and H-bond-donor acidity. The solvent o -NPOE is shown to be a good candidate to replace DCE in measurements of lipophilicity. [source] The structural organization in aqueous solutions of ionic liquidsAICHE JOURNAL, Issue 1 2009Xiao Zhu Abstract The 1H NMR combined with the local composition (LC) model has been employed to investigate the structural organization of two aqueous solutions of ionic liquids (ILs), namely 1-ethyl-3-methylimidazolium tetrafluoroborate (EmimBF4) and n-butylammonium nitrate (N4NO3). The correlation of chemical shifts using the LC model shows that the self-association of IL plays the leading role, and water prefers to interact with IL rather than self-association in IL-rich region. Instead the network of water molecules is established in water-rich region, because the self-association of water predominates. Furthermore, the difference between the local and the bulk composition presents the turnover at x(IL) (mole fraction of IL) close to 0.6 for EmimBF4/water, which is in accordance with the change of excess function. Accordingly, it could be presumed that the excess properties for N4NO3/water system should behave turnover at x(IL) , 0.55 since the local and the bulk exhibit maximal difference at this composition. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Drug,Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water, and Octan-1-ol/Water SystemsHELVETICA CHIMICA ACTA, Issue 2 2010Xiangli Liu Abstract The objective of this study was to investigate drug,membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log,Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan-1-ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti-inflammatory drugs and , -blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH,7.4. No correlation was found between log,Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log,Ks from ILC and lipophilicity indices from IAM chromatography and octan-1-ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. [source] Interaction of non-ionic hydrogels with weak aromatic acidsMACROMOLECULAR SYMPOSIA, Issue 1 2003Krisztina László Abstract Measurements are reported of the swelling behaviour at 20°C of poly (N isopropylacrylamide) (PNIPA) gels in aqueous solutions of two weak aromatic acids, phenol and resorcinol. For solute concentrations below 45 mmol/l the uptake of these solutions is similar. Due to selective solvation phenol exhibits an excess equilibrium concentration inside the gel of 5% over that in the surrounding bath, while for resorcinol, the excess is found to be 12%. At 50 mmol/l solute concentration, both systems display a volume transition accompanied by expulsion of the solvent. The solubility limits in water of these aromatic compounds, which are significantly different from each other (870 mmol/l and 9080 mmol/l respectively), are far above this critical concentration. In the collapsed condition the expelled liquid spreads on the surface of the phenol treated gel, while an ordered arrangement of separate droplets is generated in the case of resorcinol. In the latter case an acute contact angle was observed. It is also shown by acid-base titration that the PNIPA/water system may exhibit a slight ion exchanging character. [source] Development and Evaluation of an Ozonated Water System for Antimicrobial Treatment of Durum WheatJOURNAL OF FOOD SCIENCE, Issue 7 2009B. Dhillon ABSTRACT:, Ozonated water is reported to be effective in reducing the microbial load in foods such as fruits, vegetables, and grains. Ozonated water may be an effective alternative to chlorinated water in treating durum wheat before milling. Therefore, durum wheat was washed with ozonated water and analyzed for yeast and mold count (YMC) and aerobic plate count (APC). A system for producing and monitoring ozonated water was developed. The effect of water quality (tap, distilled, and ultra-pure), temperature (7, 15, and 25 °C), and pH (2, 4, and 6.5) was evaluated on the following: steady-state dissolved ozone concentration, ozone decay constant, half-life, mass transfer coefficient, equilibrium ozone concentration, and solubility ratio. The study of these parameters was important to attain a stable, high dissolved ozone concentration at the outset of washing and to have information for system improvement and scale-up. A 1% acetic acid solution (pH 2) at 15 °C resulted in high dissolved ozone concentration (21.8 mg/L) and long half-life (9.2 min). Subsequently, wheat was washed with 5 wash water types: distilled water, ozonated water (16.5 mg/L), chlorinated water (700 mg/L), acetic acid solution (1%), and acetic acid + ozonated water (1%, 20.5 mg/L). The treated samples were analyzed for YMC and APC. The acetic acid + ozonated water treatment was the most effective, with a reduction of 4.1 and 3.2 log10 colony forming units/g in YMC and APC, respectively. Though ozonated water was not very effective alone, it was useful in combination with acetic acid. [source] Evaluation of Cu,Ethylenediamine Metal Ion Buffers as Calibrants for Ion-Selective Electrode Measurement of Copper in Fresh Water SystemsELECTROANALYSIS, Issue 10 2005Ling Zeng Abstract An investigation was made into the accuracy of cupric ion selective electrode (ISE) measurement of Cu in solutions approximating acidic freshwaters with Cu-ethylenediamine buffers used as the calibrants. This method overestimates the free Cu compared with calibration using Cu(NO3)2 standards, the standard addition method, and speciation modelling calculations. Statistical tests showed a small, but significant, difference between the intercepts of the linear Nernstian regressions of the calibration plots of Cu-en buffer standardisation and direct calibration with Cu(NO3)2 standards in matrix that matches the samples. The difference in the intercepts, which corresponds with Eo values of the electrode, is not well understood, but is possibly caused by potentially interfering cations such as Fe2+. The results of this study showed that down to 10,8,M Cu2+, where a linear Nernstian response is possible, the Cu ISE is probably better calibrated using Cu standards prepared in the same matrix as the sample solutions to avoid potential matrix effects. [source] Selected Characteristics of Ground Water-Supplied Community Water SystemsGROUND WATER MONITORING & REMEDIATION, Issue 2 2004Charles Job First page of article [source] Ground Water-Supplied Public Water Systems: A 10-Year ComparisonGROUND WATER MONITORING & REMEDIATION, Issue 1 2004Charles Job First page of article [source] Regulation of Arsenic in Drinking Water Affects Ground Water SystemsGROUND WATER MONITORING & REMEDIATION, Issue 1 2002Charles Job First page of article [source] Urban Water Systems Modelling for Water Removal and Ecological Functions William James (Ed) Practical Modeling of Urban Water Systems: Monograph 11 Computaional Hydraulics Int., Guelph, Canada, 511 pp, 2003, ISBN 0-968-36817-4HYDROLOGICAL PROCESSES, Issue 3 2004Theodore A. Endreny First page of article [source] Colonization of Legionella Species in Hotel Water Systems in TurkeyJOURNAL OF TRAVEL MEDICINE, Issue 6 2007Haluk Erdogan MD Background The goal of this study was to evaluate the prevalence of Legionella species in hotel water distribution systems in Alanya, Turkey, which is an important tourism center. Methods Water and swab samples were obtained from 52 Turkish hotels from August 2003 to September 2005. Water samples were collected in 100 mL sterile containers and were concentrated by membrane filters with a pore size of 0.45 ,m. Heat treatment was used to eliminate other microorganisms from the samples, which were then spread on buffered charcoal yeast extract , agar plates and glycine, vancomycin, polymyxin, cycloheximide agar plates. Cysteine-dependent colonies were identified by latex agglutination. Results In all, 491 water and swab samples were analyzed. The results of all samples were negative for Legionella in 16 (30.8%) hotels. Legionella species (92.5% of which were Legionella pneumophila) were detected in 93 (18.9%) of the samples. The most frequently isolated species were L pneumophila serogroups 6 (63.5%) and 1 (21.5%). ConclusionsLegionella pneumophila serogroup 6 was the most common isolate detected in Turkish hotel water systems in our study. The result of Legionella urinary antigen tests, which are the diagnostic tests most often used to identify legionnaires' disease, may be negative in people infected with L pneumophila serogroup 6. We suggest that clinicians should apply the whole spectrum of laboratory methods for the detection of legionnaires' disease in patients with pneumonia of unknown origin and history of travel to Alanya, Turkey. [source] Skin Permeation of Testosterone and its Ester Derivatives in RatsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000MI-KYEONG KIM To establish the optimum conditions for improving the transdermal delivery of testosterone, we studied the relationship between the lipophilicity of testosterone ester derivatives and the rat skin permeation rate of testosterone. We performed a rat skin permeation study of testosterone and its commercially available ester derivatives, testosterone hemisuccinate, testosterone propionate and testosterone-17,-cypionate, using an ethanol/water co-solvent system. The aqueous solubility and rat skin permeation rate of each drug, saturated in various compositions of an ethanol/water system, was determined at 37°C. The aqueous solubility of testosterone and its ester derivatives increased exponentially as the volume fraction of ethanol increased up to 100% (v/v). The stability of testosterone propionate in both the skin homogenate and the extract was investigated to observe the enzymatic degradation during the skin permeation process. Testosterone propionate was found to be stable in the isotonic buffer solution and in the epidermis-side extract for 10 h at 37°C. However, in the skin homogenate and the dermis-side extract testosterone propionate rapidly degraded producing testosterone, implying that testosterone propionate rapidly degraded to testosterone during the skin permeation process. The steady-state permeation rates of testosterone in the ethanol/water systems increased exponentially as the volume fraction of ethanol increased, reaching the maximum value (2.69 ± 0.69 ,g cm,2 h,1) at 70% (v/v) ethanol in water, and then decreasing with further increases in the ethanol volume fraction. However, in the skin permeation study with testosterone esters saturated in 70% (v/v) ethanol in water system, testosterone esters were hardly detected in the receptor solution, probably due to the rapid degradation to testosterone during the skin permeation process. Moreover, a parabolic relationship was observed between the permeation rate of testosterone and the log P values of ester derivatives. Maximum flux was achieved at a log P value of around 3 which corresponded to that of testosterone (log P = 3.4). The results showed that the skin permeation rate of testosterone and its ester derivatives was maximized when these compounds were saturated in a 70% ethanolic solution. It was also found that a log P value of around 3 is suitable for the skin permeation of testosterone related compounds. [source] A New Photothermal Therapeutic Agent: Core-Free Nanostructured AuxAg1,x DendritesCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008Kuo-Wei Hu Abstract A new class of AuxAg1,x nanostructures with dendrite morphology and a hollow interior were synthesized by using a replacement reaction between Ag dendrites and an aqueous solution of HAuCl4. The Ag nanostructured dendrites were generated by the reaction of AgNO3 with ascorbic acid in a methanol/water system. The dendrites resemble a coral shape and are built up of many stems with an asymmetric arrangement. Each stem is approximately 400,nm in length and 65,nm in diameter. The bimetallic composition of AuxAg1,x can be tuned by the addition of different amounts of HAuCl4 to the Ag dendritic solution. The hollowing process resulted in tubular structures with a wall thickness of 10.5,nm in Au0.3Ag0.7 dendrites. The UV/Vis spectra indicate that the strongest NIR absorption among the resulting hollow AuxAg1,x dendrites was in Au0.3Ag0.7. The MTT assay was conducted to evaluate the cytotoxicity of Ag dendrites, hollow Au0.06Ag0.94 and Au0.3Ag0.7 dendrites, and Au nanorods. It was found that hollow Au0.06Ag0.94 and Au0.3Ag0.7 dendrites exhibited good biocompatibility, while both Ag dendrites and Au nanorods showed dose-dependent toxicity. Because of absorption in the NIR region, hollow Au0.3Ag0.7 dendrites were used as photothermal absorbers for destroying A549 lung cancer cells. Their photothermal performance was compared to that of Au nanorod photothermal therapeutic agents. As a result, the particle concentration and laser power required for efficient cancer cell damage were significantly reduced for hollow Au0.3Ag0.7 dendrites relative to those used for Au nanorods. The hollow Au0.3Ag0.7 nanostructured dendrites show potential in photothermolysis for killing cancer cells. [source] Experimental and modeling investigation of metal release from metal-spiked sedimentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2005Richard F. Carbonaro Abstract In sediments that contain iron monosulfide, cadmium, nickel, lead, zinc, and silver(I) form insoluble metal sulfides that lower the metal ion activity in the sediment,pore water system, thereby reducing toxicity. However, metal sulfides are susceptible to oxidation by molecular oxygen resulting in metal solubilization. To better understand the sources and sinks of metal sulfides in sediments, iron monsulfide,rich freshwater sediments were spiked with cadmium, nickel, lead, zinc, or silver(I) and placed into cylindrical cores with an overlying layer of oxygen-saturated water. Measurements of the dissolved metal concentration in the overlying water were made as a function of time and the vertical profiles of acid-volatile sulfide (AVS) and simultaneously extracted metal (SEM) were measured after 150 d. A one-dimensional reactive and transport model has been employed to help elucidate processes controlling the fate of metals in sediments. The model incorporates metal-sulfide formation, metal-sulfide oxidation, and metal partitioning onto sediment organic carbon and iron oxyhydroxide to simulate the vertical transport of metals throughout the sediment core. [source] Geochemistry of Extremely Alkaline (pH > 12) Ground Water in Slag-Fill AquifersGROUND WATER, Issue 6 2005George S. Roadcap Extremely alkaline ground water has been found underneath many shuttered steel mills and slag dumps and has been an impediment to the cleanup and economic redevelopment of these sites because little is known about the geochemistry. A large number of these sites occur in the Lake Calumet region of Chicago, Illinois, where large-scale infilling of the wetlands with steel slag has created an aquifer with pH values as high as 12.8. To understand the geochemistry of the alkaline ground water system, we analyzed samples of ground water and the associated slag and weathering products from four sites. We also considered several potential remediation schemes to lower the pH and toxicity of the water. The principal cause of the alkaline conditions is the weathering of calcium silicates within the slag. The resulting ground water at most of the sites is dominated by Ca2+ and OH, in equilibrium with Ca(OH)2. Where the alkaline ground water discharges in springs, atmospheric CO2 dissolves into the water and thick layers of calcite form. Iron, manganese, and other metals in the metallic portion of the slag have corroded to form more stable low-temperature oxides and sulfides and have not accumulated in large concentrations in the ground water. Calcite precipitated at the springs is rich in a number of heavy metals, suggesting that metals can move through the system as particulate matter. Air sparging appears to be an effective remediation strategy for reducing the toxicity of discharging alkaline water. [source] Michigan Basin Regional Ground Water Flow Discharge to Three Great LakesGROUND WATER, Issue 4 2002John Robert Hoaglund III Ground water discharge to the Great Lakes around the Lower Peninsula of Michigan is primarily from recharge in riparian basins and proximal upland areas that are especially important to the northern half of the Lake Michigan shoreline. A steady-state finite-difference model was developed to simulate ground water flow in four regional aquifers in Michigan's Lower Peninsula: the Glaciofluvial, Saginaw, Parma-Bayport, and Marshall aquifers interlayered with the Till/"red beds," Saginaw, and Michigan confining units, respectively. The model domain was laterally bound by a continuous specified-head boundary, formed from lakes Michigan, Huron, St. Clair, and Erie, with the St. Clair and Detroit River connecting channels. The model was developed to quantify regional ground water flow in the aquifer systems using independently determined recharge estimates. According to the flow model, local stream stages and discharges account for 95% of the overall model water budget; only 5% enters the lakes directly from the ground water system. Direct ground water discharge to the Great Lakes' shorelines was calculated at 36 m3/sec, accounting for 5% of the overall model water budget. Lowland areas contribute far less ground water discharge to the Great Lakes than upland areas. The model indicates that Saginaw Bay receives only ,1.13 m3/sec ground water; the southern half of the Lake Michigan shoreline receives only ,2.83 m3/sec. In contrast, the northern half of the Lake Michigan shoreline receives more than 17 m3/sec from upland areas. [source] Ground Water Flow Analysis of a Mid-Atlantic Outer Coastal Plain Watershed, Virginia, U.S.A.GROUND WATER, Issue 2 2002Michael A. Robinson Models for ground water flow (MODFLOW) and particle tracking (MODPATH) were used to determine ground water flow patterns, principal ground water discharge and recharge zones, and estimates of ground water travel times in an unconfined ground water system of an outer coastal plain watershed on the Delmarva Peninsula, Virginia. By coupling recharge and discharge zones within the watershed, flowpath analysis can provide a method to locate and implement specific management strategies within a watershed to reduce ground water nitrogen loading to surface water. A monitoring well network was installed in Eyreville Creek watershed, a first-order creek, to determine hydraulic conductivities and spatial and temporal variations in hydraulic heads for use in model calibration. Ground water flow patterns indicated the convergence of flow along the four surface water features of the watershed; primary discharge areas were in the noontide portions of the watershed. Ground water recharge zones corresponded to the surface water features with minimal development of a regional ground water system. Predicted ground water velocities varied between < 0.01 to 0.24 m/day, with elevated values associated with discharge areas and areas of convergence along surface water features. Some ground water residence times exceeded 100 years, although average residence times ranged between 16 and 21 years; approximately 95% of the ground water resource would reflect land use activities within the last 50 years. [source] Analytical Studies on the Impact of Land Reclamation on Ground Water FlowGROUND WATER, Issue 6 2001Jiu J. Jiao Land reclamation has been a common practice to produce valuable land in coastal areas. The impact of land reclamation on coastal environment and marine ecology is well recognized and widely studied. It has not been recognized yet that reclamation may change the regional ground water regime, which may in turn modify the coastal environment, flooding pattern, and stability of slopes and foundations. This paper represents the first attempt to examine quantitatively the effect of reclamation on ground water levels. Analytical solutions are developed to study the ground water change in response to reclamation based on two hypothetical models. In the first model, the ground water flow regime changes only in the hillside around the reclamation areas. In the second model, the ground water regime changes in the entire hill. Both models assume that the ground water flow is in a steady state and satisfies the Dupuit assumptions. Hypothetical examples are used to demonstrate how the ground water level, ground water divide and ground water submarine discharge will change with the scale and hydraulic conductivity of the reclamation materials. The results show that the change of ground water regime depends mainly on the length of the reclaimed area and the values of hydraulic conductivity of the reclaimed materials. It is also seen that the reclamation may impact not only the ground water regime near the coast areas around the reclamation site, but also that in the coast areas opposite the reclamation area. A reclamation site near Tseung Kwan O in the New Territories in Hong Kong, China, is used as a case study to discuss the possible modification of the ground water system caused by reclamation. [source] A First Estimate of Ground Water Ages for the Deep Aquifer of the Kathmandu Basin, Nepal, Using the Radioisotope Chlorine-36GROUND WATER, Issue 3 2001Richard G. Cresswell The Kathmandu Basin in Nepal contains up to 550 m of Pliocene-Quaternary fluvio-lacustrine sediments which have formed a dual aquifer system. The unconfined sand and gravel aquifer is separated by a clay aquitard, up to 200 m thick, from the deeper, confined aquifer, comprised of Pliocene sand and gravel beds, intercalated with clay, peat, and lignite. The confined aquifer currently provides an important water supply to the central urban area but there are increasing concerns about its sus-tainability due to overexploitation. A limited number of determinations of the radioisotope 36Cl have been made on bore waters in the basin, allowing us to postulate on the age of ground water in the deeper, confined aquifer. Ground water evolution scenarios based on radioisotope decay, gradual dissolution of formational salts as the ground waters move downgradient, and flow velocity estimations produce comparable ground water ages for the deep waters, ranging from 200,000 to 400,000 years. From these ages, we deduce a mean ground water flow velocity of only 45 mm/year from recharge in the northeast to the main extraction region 15 km to the southwest. We thus estimate current recharge at about 5 to 15 mm/year, contributing 40,000 to 1.2 million m3/year to the ground water system. Current ground water extraction is estimated to be 20 times this amount. The low specific discharge confirms that the resource is being mined, and, based on current projections, reserves will be used up within 100 years. [source] Wetlands with controlled drainage and sub-irrigation systems,modelling of the water balanceHYDROLOGICAL PROCESSES, Issue 14 2007Ottfried Dietrich Abstract Over the past centuries, the agricultural use of wetlands in Central Europe has required interference with the natural wetland water balance. Often this has consisted of drainage measures alone. In low-precipitation areas, it has also involved the operation of combined drainage and sub-irrigation systems. Model studies conducted as part of planning processes, or with a view to finding out the impact of changing climate conditions on the water balance of wetlands, must take these facts into account. For this reason, a water balance model has been devised for wetlands whose water balance is governed by water resources management systems. It is based on the WBalMo model system. Special modules were integrated into WBalMo to calculate the water balance of wetland areas (WABI module) and to regulate inflow partitioning within the wetland (REGINF module). When calculating the water balance, the WABI module takes into account precipitation and potential evapotranspiration, groundwater levels below surface, soil types, land-use classes, inflows via the running water system, and data for target water levels. It provides actual evapotranspiration, discharge into the running water system, and groundwater levels in the area. The example of the Spreewald, a major wetland area in north-eastern Germany, was used to design and test the WBalMo Spreewald model. The comparison of measured and calculated water balance parameters of the wetland area confirms the suitability of the model for water balance studies in wetlands with complex water resources management systems. The results reveal the strong influence of water management on the water balance of such areas. The model system has proved to be excellently suited for planning and carrying out water management measures aimed at the sustainable development of wetlands. Furthermore, scenario analyses can be used to assess the impact of global change on the water balance of wetlands. Copyright © 2006 John Wiley & Sons, Ltd. [source] Reducing risk of shortages due to drought in water supply systems using genetic algorithms,IRRIGATION AND DRAINAGE, Issue 2 2009V. Nicolosi évaluation des risques; gestion de l'eau; sécheresse; éléments déclenchant pour les plans sécheresse Abstract The evaluation of risk of shortages due to drought in water supply systems is a necessary step both in the planning and in the operation stage. A methodology for unconditional (planning) and conditional (operation) risk evaluation is presented in this study. The risk evaluation is carried out by means of an optimisation model based on genetic algorithms aimed to define thresholds for the implementation of mitigation measures tested through Monte Carlo simulation that makes use of a stochastic generation of streamflows. The GA enables the optimisation of reservoir storages which identify monthly thresholds for shifting three states of the system (normal, alert and alarm) to which correspond different mitigation measures such as water demand rationing, additional supplies from alternative sources or reduction of release for ecological use. For unconditional risk evaluation a long time horizon has been considered (40 years), while the conditional risk evaluation is performed on a short time horizon (2,3 months). Results of simulations have been studied by means of consolidated indices of performance and frequency analysis of shortages of a given entity corresponding to different planning/management policies. A multi-use water system has been used as a case study including competing irrigation and industrial demands. Copyright © 2008 John Wiley & Sons, Ltd. L'évaluation du risque de manques d'eau dus à la sécheresse dans les systèmes d'approvisionnement en eau est une étape nécessaire à la fois pour la planification et l'exploitation. Une méthodologie pour l'évaluation du risque inconditionnel (planification) et conditionnel (exploitation) est présentée dans cette étude. L'évaluation du risque est effectuée au moyen d'un modèle d'optimisation basé sur des algorithmes génétiques visant à définir des seuils pour la mise en ,uvre des mesures d'atténuation testés par une méthode de Monte Carlo générant les débits des rivières. L'algorithme génétique permet d'optimiser les stockages de réservoir avec des seuils mensuels pour identifier trois états du système (normal, alerte et alarme) auxquels correspondent différentes mesures d'atténuation telles que rationnement de la demande en eau, approvisionnements complémentaires par des sources alternatives ou réduction des lâchures pour l'usage écologique. Pour l'évaluation des risques inconditionnels un horizon à long terme a été considéré (40 ans) tandis que l'évaluation conditionnelle est faite sur un horizon à court terme (2 ou 3 mois). Les résultats des simulations ont été étudiés au moyen d'indices de performance consolidés et de l'analyse de la fréquence des manques d'eau pour une entité donnée correspondant à différentes politiques de planification et gestion. L'étude de cas porte sur un système multi-usage comportant une demande d'irrigation en concurrence avec les demandes industrielles. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effects of dietary l -tryptophan and lighting conditions on growth performance of European sea bass (Dicentrarchus labrax) juveniles reared in a recirculating water systemJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2005S. E. Papoutsoglou Summary The aim of the present study was to investigate possible stressful effects on European sea bass Dicentrarchus labrax reared under constant darkness (0L-24D) and to examine the possible anti-stressful effect of dietary tryptophan (TRP) supplementation. Juvenile European sea bass (initial body weight 4.23 ± 0.032 g) were reared for 10 weeks under 0L-24D and 12L-12D and fed either a commercial diet (0.47% TRP) or the same diet supplemented with L-TRP (2.47% TRP). Results showed that lighting conditions had no significant effect on fish growth, while a depressive effect by the TRP supplementation was obvious. All fish populations reared under 0L-24D exhibited reduced body protein, lipid and ash content and increased food consumption. Reduced body lipids, food consumption and nutrient utilization were observed in TRP-supplemented fed fish, along with lower liver lipids. Dietary TRP enrichment significantly lowered liver saturated and monounsaturated acids and increased poly- and highly-unsaturated fatty acids, especially in combination with 0L-24D. These changes were also considerably reflected in carcass fatty acid composition. [source] Viable ultramicrocells in drinking waterJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2009F.S. Silbaq Abstract Aims:, To examine the diversity of cultivable 0·2 micron filtrate biofilm forming bacteria from drinking water systems. Methods and Results:, Potable chlorinated drinking water hosts phylogenetically diverse ultramicrocells (UMC) (0·2 and 0·1 ,m filterable). UMC (starved or dwarf bacteria) were isolated by cultivation on minimal medium from a flow system wall model with polyvinyl chloride (PVC) pipes. All cultivated cells (25 different isolates) did not maintain their ultra-size after passages on rich media. Cultured UMC were identified by their 16S ribosomal DNA sequences. The results showed that they were closely related to uncultured and cultured members of the Proteobacteria, Actinobacteria and Firmicutes. The isolates of phylum Actinobacteria included representatives of a diverse set of Actinobacterial families: Micrococcaceae, Microbacteriaceae, Dermabacteraceae, Nocardiaceae and Nocardioidaceae. Conclusions:, This study is the first to show an abundance of cultivable UMC of various phyla in drinking water system, including a high frequency of bacteria known to be involved in opportunistic infections, such as Stenotrophomonas maltophilia, Microbacterium sp., Pandoraea sp. and Afipia strains. Significance and Impact of the Study:, Chlorinated tap water filtrate (0·2 and 0·1 ,m) still harbours opportunistic micro-organisms that can pose some health threat. [source] Protecting the Nation's Critical Infrastructure: The Vulnerability of U.S. Water Supply SystemsJOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 2 2000Robert M. Clark Terrorism in the United States was not considered a serious threat until the second half of the 1990s. However, recent attacks both at home and abroad have forced government planners to consider the possibility that critical elements of the U.S. infrastructure might in fact be vulnerable to terrorism. The potential for chemical or biological contamination of water supply systems exists along with the possibility that such systems might be sabotaged. This article reviews the threat of biological and chemical compounds in relation to the characteristics of water supply systems. Vulnerability of such systems to terrorist attacks is examined, as well as possible physical and chemical countermeasures that could be applied. A case study is presented of an accidental contamination event that illustrates the difficulty of tracking such events in a drinking water system. It can be concluded that municipal water supplies are vulnerable. However, appropriate physical planning of such systems, including contingency back-up with separate water lines for emergencies, coupled with proactive monitoring, will significantly increase security in the face of possible terrorist attacks. [source] Optimal design of single-contaminant regeneration reuse water networks with process decompositionAICHE JOURNAL, Issue 4 2010Jie Bai Abstract Water network with regeneration schemes (e.g., regeneration reuse, regeneration recycling) can reduce freshwater consumption further than water network merely with direct reuse. Regeneration reuse, compared with regeneration recycling, can additionally avoid unexpected accumulation of contaminants. Owing to these features, process decomposition can help to reduce freshwater usage and wastewater discharge of regeneration reuse water systems and achieve the results, which graphical method delivers. In this article, the effect of decomposition on water-using process and further on regeneration reuse water system is briefly analyzed on the concentration-mass load diagram. Then a superstructure and three sequential mathematical models, which take process decomposition into account, are in turn developed to optimize single contaminant regeneration reuse water systems. By several examples, the reliability of the models is verified. Moreover, several decomposition strategies are summarized to realize the regeneration reuse water network, which attains the targets from graphical method. The results indicate that postregeneration concentration has a major impact on the scheme of process decomposition. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Liquid,liquid miscibility gaps and hydrate formation in drug,water binary systems: Pressure,temperature phase diagram of lidocaine and pressure,temperature,composition phase diagram of the lidocaine,water systemJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2010René Ceolin Abstract The pressure,temperature (P,T) melting curve of lidocaine was determined (dP/dT,=,3.56,MPa,K,1), and the lidocaine,water system was investigated as a function of temperature and pressure. The lidocaine,water system exhibits a monotectic equilibrium at 321,K (ordinary pressure) whose temperature increases as the pressure increases until the two liquids become miscible. A hydrate, unstable at ordinary pressure, was shown to form, on increasing the pressure, from about 70,MPa at low temperatures (200,300,K). The thermodynamic conditions of its stability were inferred from the location of the three-phase equilibria involving the hydrate in the lidocaine,water pressure,temperature,mole fraction (P,T,x) diagram. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2756,2765, 2010 [source] Skin Permeation of Testosterone and its Ester Derivatives in RatsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2000MI-KYEONG KIM To establish the optimum conditions for improving the transdermal delivery of testosterone, we studied the relationship between the lipophilicity of testosterone ester derivatives and the rat skin permeation rate of testosterone. We performed a rat skin permeation study of testosterone and its commercially available ester derivatives, testosterone hemisuccinate, testosterone propionate and testosterone-17,-cypionate, using an ethanol/water co-solvent system. The aqueous solubility and rat skin permeation rate of each drug, saturated in various compositions of an ethanol/water system, was determined at 37°C. The aqueous solubility of testosterone and its ester derivatives increased exponentially as the volume fraction of ethanol increased up to 100% (v/v). The stability of testosterone propionate in both the skin homogenate and the extract was investigated to observe the enzymatic degradation during the skin permeation process. Testosterone propionate was found to be stable in the isotonic buffer solution and in the epidermis-side extract for 10 h at 37°C. However, in the skin homogenate and the dermis-side extract testosterone propionate rapidly degraded producing testosterone, implying that testosterone propionate rapidly degraded to testosterone during the skin permeation process. The steady-state permeation rates of testosterone in the ethanol/water systems increased exponentially as the volume fraction of ethanol increased, reaching the maximum value (2.69 ± 0.69 ,g cm,2 h,1) at 70% (v/v) ethanol in water, and then decreasing with further increases in the ethanol volume fraction. However, in the skin permeation study with testosterone esters saturated in 70% (v/v) ethanol in water system, testosterone esters were hardly detected in the receptor solution, probably due to the rapid degradation to testosterone during the skin permeation process. Moreover, a parabolic relationship was observed between the permeation rate of testosterone and the log P values of ester derivatives. Maximum flux was achieved at a log P value of around 3 which corresponded to that of testosterone (log P = 3.4). The results showed that the skin permeation rate of testosterone and its ester derivatives was maximized when these compounds were saturated in a 70% ethanolic solution. It was also found that a log P value of around 3 is suitable for the skin permeation of testosterone related compounds. [source] Synthesis of Nano-sized BaTiO3 Powders by the Rotary-Hydrothermal ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2009Takashi Kubo Nano-sized BaTiO3 powders with narrow size distribution and high tetragonality were attempted to be synthesized by the rotary-hydrothermal process in a water system as a novel technique, using a mixture of anatase-type TiO2 and Ba(OH)2 as starting material. The rotary-hydrothermal syntheses were performed under conditions with a rotary-speed of 20 revolutions per minute at 423,523 K for 3,96 h. Highly- and mono-dispersed BaTiO3 powders mainly composed of coarse-faceted particles with the tetragonal phase were successfully synthesized by controlling the conditions for rotary-hydrothermal treatments. TEM and TG results revealed that these coarse-faceted BaTiO3 particles contained very few structural defects such as hydroxyl content. Thus, the rotary-hydrothermal process was a useful method to synthesize very high-quality BaTiO3 particles, and the further control of various conditions of the rotary-hydrothermal treatment is expected to control the crystalline phase and microstructures of final BaTiO3 powders. [source] Effects of the Prebiotics GroBiotic® -A and Inulin on the Intestinal Microbiota of Red Drum, Sciaenops ocellatusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2009Gary Burr Two separate feeding trials examined the effects of dietary supplementation of the prebiotics GroBiotic® -A and inulin on growth performance and gastrointestinal tract microbiota of the red drum, Sciaenops ocellatus. In the first feeding trial, fish meal-based diets without prebiotics or supplemented with either GroBiotic® -A or inulin at 1% of dry weight were fed to triplicate groups of juvenile red drum (initial weight of 2.6 g) in 110-L aquaria operated as a brackish water (7 ppt) recirculating system for 8 wk. In the second feeding trial, soybean meal/fish meal-based diets supplemented with either GroBiotic® -A or inulin at 1% of dry weight were fed to triplicate groups of red drum (initial weight of 15.8 g) in 110-L aquaria operated as either a common recirculating water system or closed system with individual biofilters (independent aquaria) for 6 wk. Supplementation of the prebiotics in either feeding trial did not alter weight gain, feed efficiency ratio, or protein efficiency ratio of red drum fed the various diets. In the second feeding trial, the culture system significantly affected weight gain, feed efficiency ratio, and protein efficiency ratio although there were no effects of dietary treatments on fish performance or whole-body protein, lipid, moisture, or ash. Denaturing gradient gel electrophoresis (DGGE) analysis of the gastrointestinal tract microbial community showed no effect of the dietary prebiotics as the microbial community appeared to be dominated by a single organism with very low diversity when compared with other livestock and fish species. DGGE of the microbial community in the biofilters of the independent aquariums showed a diverse microbial community that was not affected by the dietary prebiotics. [source] | |||||||||||||||||||||||||||||||