Water

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Water

  • Drink water
  • acid water
  • acidic water
  • adding water
  • additional water
  • adjacent water
  • alkaline water
  • ambient water
  • and water
  • anoxic water
  • australian water
  • available soil water
  • available water
  • ballast water
  • bath water
  • body water
  • boiling water
  • bottled water
  • bottom water
  • bound water
  • brackish water
  • buffered peptone water
  • bulk water
  • clean water
  • clear water
  • coastal water
  • coconut water
  • cold water
  • colder water
  • containing water
  • contaminated ground water
  • contaminated irrigation water
  • contaminated water
  • control water
  • cool water
  • cooler water
  • cooling water
  • coordinated water
  • de-ionized water
  • deep ground water
  • deep water
  • deeper water
  • deionized water
  • deuterated water
  • distilled water
  • drainage water
  • drink water
  • drinking water
  • electrolyzed water
  • environmental water
  • estuarine water
  • european water
  • excess water
  • explicit water
  • extracellular water
  • extravascular lung water
  • filtered water
  • flood water
  • flowing water
  • fluoridated water
  • food and water
  • formation water
  • free water
  • fresh water
  • geothermal water
  • ground water
  • gulf water
  • heavy water
  • high water
  • hot water
  • hyporheic water
  • icelandic water
  • industrial water
  • inland water
  • inshore water
  • interstitial water
  • intracellular water
  • irrigation water
  • lake water
  • leaf water
  • liquid hot water
  • liquid water
  • low salinity water
  • low water
  • low-salinity water
  • magmatic water
  • marine water
  • melt water
  • meteoric water
  • milli-q water
  • mineral water
  • molecular water
  • natural water
  • near-shore water
  • neat water
  • neutral water
  • nutrient-rich water
  • ocean water
  • oceanic water
  • offshore water
  • open water
  • overlying water
  • ozonated water
  • pelagic water
  • peptone water
  • phreatic water
  • polluted water
  • pond water
  • pore water
  • potable water
  • precipitable water
  • process water
  • pure water
  • quality water
  • rain water
  • raw water
  • receiving water
  • river water
  • running water
  • safe water
  • saline ground water
  • saline water
  • salinity water
  • salt water
  • sample water
  • sea water
  • sediment pore water
  • sewage water
  • shallow ground water
  • shallow water
  • shallower water
  • shelf water
  • soil water
  • solvent water
  • sorbed water
  • source water
  • spring water
  • standing water
  • sterile water
  • stored water
  • storm water
  • stream water
  • structural water
  • subcritical water
  • subsurface water
  • subtropical water
  • sufficient water
  • supercritical water
  • surface water
  • surrounding water
  • tap water
  • temperate water
  • thermal water
  • tissue water
  • total body water
  • total water
  • treated water
  • tritiated water
  • tropical water
  • turbid water
  • vegetation water
  • warm water
  • wash water
  • waste water
  • xylem water

  • Terms modified by Water

  • water absorption
  • water absorption capacity
  • water absorption index
  • water absorption property
  • water abstraction
  • water act
  • water activity
  • water ad libitum
  • water addition
  • water adsorption
  • water agar
  • water allocation
  • water alone
  • water amount
  • water analysis
  • water area
  • water assessment tool
  • water authority
  • water availability
  • water available
  • water balance
  • water balance component
  • water balance model
  • water balance studies
  • water basin
  • water bath
  • water beetle
  • water bloom
  • water body
  • water budget
  • water buffalo
  • water capacity
  • water chain
  • water change
  • water channel
  • water channel protein
  • water chemistry
  • water circulation
  • water clarity
  • water cluster
  • water colour
  • water column
  • water column depth
  • water company
  • water composition
  • water concentration
  • water condensation
  • water condition
  • water conductivity
  • water conservation
  • water consumption
  • water contact angle
  • water contact angle measurement
  • water containing
  • water contamination
  • water content
  • water control
  • water cooling
  • water course
  • water current
  • water cycle
  • water data
  • water decreased
  • water deficiency
  • water deficit
  • water delivery
  • water demand
  • water density
  • water deprivation
  • water depth
  • water development
  • water diffusion
  • water diffusion coefficient
  • water dilution
  • water dimer
  • water dip
  • water dissociation
  • water distribution
  • water distribution coefficient
  • water distribution system
  • water district
  • water diversion
  • water droplet
  • water dynamics
  • water ecosystem
  • water electrolysis
  • water elevation
  • water emulsion
  • water environment
  • water equation
  • water equivalent
  • water erosion
  • water erosion prediction project
  • water evaporation
  • water exchange
  • water exchange rate
  • water exchanges
  • water excretion
  • water exposure
  • water extract
  • water extraction
  • water feature
  • water film
  • water fish
  • water flea daphnia magna
  • water flow
  • water flow model
  • water flow velocity
  • water flux
  • water fraction
  • water framework directive
  • water gas shift reaction
  • water gasification
  • water gradient
  • water group
  • water habitat
  • water head
  • water heating
  • water homeostasi
  • water ice
  • water immersion
  • water increase
  • water industry
  • water inflow
  • water influx
  • water infrastructure
  • water infusion
  • water injection
  • water input
  • water intake
  • water interaction
  • water interface
  • water intoxication
  • water intrusion
  • water irrigation
  • water isotope
  • water layer
  • water lead
  • water level
  • water level fluctuation
  • water ligand
  • water limitation
  • water line
  • water loss
  • water management
  • water management practice
  • water managers
  • water market
  • water mass
  • water maze
  • water maze task
  • water maze test
  • water maze training
  • water medium
  • water method
  • water mixture
  • water mobility
  • water model
  • water models
  • water molecule
  • water motion
  • water movement
  • water need
  • water network
  • water only
  • water oxidation
  • water parameter
  • water partition coefficient
  • water path
  • water permeability
  • water ph
  • water phase
  • water plume
  • water point
  • water policy
  • water pollution
  • water pool
  • water potential
  • water present
  • water pressure
  • water pricing
  • water problem
  • water process
  • water production
  • water project
  • water property
  • water protection
  • water proton
  • water quality
  • water quality assessment
  • water quality condition
  • water quality criterioN
  • water quality data
  • water quality deterioration
  • water quality guideline
  • water quality management
  • water quality models
  • water quality monitoring
  • water quality parameter
  • water quality problem
  • water quality standards
  • water quality variable
  • water quantity
  • water ratio
  • water regime
  • water relation
  • water remediation
  • water removal
  • water requirement
  • water reservoir
  • water residence time
  • water resistance
  • water resource
  • water resource management
  • water resource managers
  • water resources
  • water resources management
  • water resources planning
  • water resources system
  • water restriction
  • water retention
  • water retention capacity
  • water retention characteristic
  • water retention curve
  • water right
  • water runoff
  • water salinity
  • water sample
  • water sampling
  • water saturation
  • water savings
  • water scarcity
  • water sector
  • water separation
  • water services
  • water shortage
  • water signal
  • water site
  • water solubility
  • water solubility index
  • water soluble
  • water solution
  • water solvent
  • water solvent mixture
  • water sorption
  • water source
  • water splitting
  • water spray
  • water stability
  • water standard
  • water status
  • water storage
  • water storage capacity
  • water storage time
  • water stream
  • water stress
  • water stress tolerance
  • water structure
  • water supplies
  • water supply
  • water supply system
  • water surface
  • water suspension
  • water system
  • water table
  • water table condition
  • water table depth
  • water table elevation
  • water table fluctuation
  • water table position
  • water tank
  • water temperature
  • water transfer
  • water transparency
  • water transport
  • water transport capacity
  • water trap
  • water treatment
  • water treatment plant
  • water treatment process
  • water treatment system
  • water type
  • water uptake
  • water uptake behavior
  • water usage
  • water use
  • water used
  • water user
  • water user association
  • water utility
  • water vapor
  • water vapor permeability
  • water vapor transmission rate
  • water vapour
  • water vapour flux
  • water velocity
  • water vole
  • water volume
  • water washing
  • water wave
  • water well
  • water withdrawal
  • water yam
  • water year
  • water yield
  • water zone

  • Selected Abstracts


    Determination of pKa values of nonsteroidal antiinflammatory drug-oxicams by RP,HPLC and their analysis in pharmaceutical dosage forms

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2009
    Ebru Cubuk Demiralay
    Abstract In this study, pKa values were determined by using the dependence of the capacity factor on the pH of the mobile phase for four ionizable substances, namely, tenoxicam, piroxicam, meloxicam, and naproxen (I.S.). The effect of the mobile phase composition on the ionization constant was studied by measuring the pKa at different ACN concentrations, ranging from 30 to 40%. The adequate condition for the chromatographic determination of these compounds in pharmaceutical dosage forms was established based on the different retention behaviors of the species. An octadecylsilica Nucleosil C18 column (1504.6 mm, 5 ,m) was used for all the determinations. The chromatographic separation of oxicams was carried out using acetonitrile (ACN)/water at 35% v/v, containing 65 mM phosphoric acid and UV detection at a wavelength of 355 nm. The method developed was successfully applied to the simultaneous determination of these drug compounds in laboratory-prepared mixtures and their commercial pharmaceutical dosage forms. Each analysis requires no longer than 12 min. [source]


    ZSM-11 membranes: Characterization and pervaporation performance

    AICHE JOURNAL, Issue 2 2002
    Shiguang Li
    High-quality boron and aluminium-substituted ZSM-11 membranes were prepared on porous tubular supports to separate alcohols from water by pervaporation. The C1,C3 alcohols were preferentially separated from aqueous solutions through the B-ZSM-11 membrane, and the maximum flux was 1.7 kg/m2h for a 5 wt.% methanol/water mixture. The alcohol fluxes decreased as the carbon number increased. The methanol/water separation selectivity decreased with pervaporation temperature, but other alcohol/water selectivities increased. All selectivities increased with decreasing alcohol feed concentration. In a range of 1 to 50 wt. % alcohol, the separation selectivities at 333 K for the C1,C3 linear alcohols were higher than vapor/liquid equilibrium selectivities. The highest selectivities observed for methanol/water, ethanol/water, 1-propanol/water, and 2-propanol/water were 28, 97, 34, and 26, respectively, at 1 wt. % alcohol feed concentrations. The separation selectivities were based on both preferential adsorption of alcohols and differences in diffusion rates. [source]


    Preparation and evaluation of the highly cross-linked poly(1-hexadecane-co-trimethylolpropane trimethacrylate) monolithic column for capillary electrochromatography

    ELECTROPHORESIS, Issue 20 2009
    Minghua Lu
    Abstract In this paper, a novel highly cross-linked porous monolithic stationary phase having a long alkyl chain ligand (C16) was introduced and evaluated in CEC. The monolithic stationary phase was prepared by in situ copolymerization of 1-hexadecene, trimethylolpropane trimethacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in the presence of ternary porogenic solvent (cyclohexanol/1,4-butanediol/water). In preparing monoliths, the ternary cross-linker trimethylolpropane trimethacrylate was usually applied to preparing molecularly imprinted polymers or molecularly imprinted solid-phase extraction, instead of binary cross-linker ethylene dimethacrylate. 1-Hexadecene was introduced to provide the non-polar sites (C16) for chromatographic retention, while AMPS was used to generate the EOF for transporting the mobile phase through the monolithic capillary. Monolithic columns were prepared by optimizing proportion of porogenic solvent and AMPS content in the polymerization solution as well as the cross-linkers. The monolithic stationary phases could generate a strong and stable EOF in various pH values and exhibit an RP-chromatographic behavior for neutral compounds. For charged compounds, the separation was mainly based on the association of hydrophobic, electrostatic and electrophoretic interaction. [source]


    Heteroarm Star Polystyrene- block -Poly(4-vinylpyridine): Multiple Morphologies in Dilute Solutions

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2008
    Chia-Hung Lin
    Abstract Synthesis and solution morphologies of four new heteroarm star polystyrene- block -poly(4-vinylpyridine) were studied. As the water content increased, a morphological transformation of heteroarm PS4 -P4VP4 from spheres to cylinders, vesicles, and large compound vesicles was observed. The morphology of PS4 -P4VP4 in the solvent mixture of DMF/water or 1,4-dioxane/water was spherical, but changed to large compound micelles in THF/water. As the P4VP molar ratio decreased, the morphology changed from spherical mixed with cylindrical to vesicles, giant vesicles, and then to LCMs. The present study demonstrated the formation of multiple morphologies through manipulating solvent polarity and block ratio in dilute solution. [source]


    Characterization and differentiation of diverse transgenic and nontransgenic soybean varieties from CE protein profiles

    ELECTROPHORESIS, Issue 13 2007
    Carmen Garca-Ruiz
    Abstract Nowadays, soybeans are commercialized in a wide variety of colors and tones. Moreover, some pigmented seeds are being commercialized as soybeans while, on other occasions, these seeds are labeled as mung beans, azuki beans or soybean frijoles generating confusion on their identity. In this work, CE has been applied for the first time for the characterization and differentiation of different pigmented beans commercialized as soybeans. Other seeds commercialized as azuki, mung green soybeans or soybean frijoles were also analyzed. Borate buffer (at pH,8.5) containing 20% v/v ACN was used as the separation media and solution containing ACN/water (75:25 v/v) with 0.3% v/v acetic acid was used to solubilize the proteins from the samples. A 50,cm bare fused-silica capillary was employed for obtaining adequate separations in about 12,min. The CE protein pattern observed for yellow soybeans was different from that corresponding to green and red soybeans. The seeds commercialized as black soybean presented electropherograms identical or similar to those yielded by the yellow seeds with the exception of the sample labeled as black soybeans frijoles that presented a totally different pattern. In addition, CE protein profiles obtained for azuki and mung green soybeans were very similar to those corresponding to red soybeans and green soybeans, respectively. Finally, the CE method was also applied to differentiate transgenic and nontransgenic soybean varieties. Discriminant analysis, using several protein peak areas as variable, was used to successfully classify these samples. [source]


    Development of a new method for analysis of Sudan dyes by pressurized CEC with amperometric detection

    ELECTROPHORESIS, Issue 11 2007
    Shaofeng Liu
    Abstract A new analytical method, pressurized CEC (pCEC) with amperometric detection (AD) using 1.5,,m RP nonporous silica packed columns has been developed for the rapid separation and determination of four Sudan dyes in hot chilli. The influence of several experimental parameters on the retention behavior has been investigated. The electrochemical oxidation of Sudans I,IV separated by pCEC can be reliably monitored with a carbon electrode at +0.95,V (vs. Ag/AgCl). Fast and efficient separation of the analytes was achieved within 7,min by pCEC under the optimum conditions with an ACN/water (95:5%) mobile phase containing formic acid (pH,4.3), 5% acetone and 0.002% triethylamine using a separation voltage of 12,kV. The detection limits for four Sudan dyes ranged from 8.0,,10,7 to 1.2,,10,6,mol/L. To evaluate the feasibility and reliability of this method, the proposed pCEC-AD method was further demonstrated with hot chilli samples spiked with Sudan dyes. [source]


    Evaluation of mobile phase, ion pairing, and temperature influence on an HILIC-MS/MS method for L -arginine and its dimethylated derivatives detection

    JOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2008
    Giuseppe Paglia
    Abstract Asymmetric NG,,NG -dimethylarginine (ADMA) increases in diseases such as renal failure, diabetes mellitus, and hypercholesterolemia. The feasibility and utility of a hydrophilic interaction chromatography (HILIC) method for the separation of free L -arginine (Arg), ADMA, and symmetric NG,,NG, -dimethylarginine (SDMA) on a typical silica column were explored and the impact of some experimental parameters on the chromatographic behavior of these analytes was investigated. The effect of water and TFA content in mobile phase and of column temperature was investigated during the development of a fast and simple HILIC-MS/MS method that might be suitable for the quantification of free Arg, ADMA, and SDMA in plasma for routine analysis. Our results show that a good compromise between efficiency and peak shape with acceptable retention and total chromatographic run time is achieved using an ACN/water (90:10) mobile phase with TFA% as additive ranging from 0.015 to 0.025% and column temperature ranging from 25 to 30C. [source]


    ChemInform Abstract: 2-Iodoxybenzoic Acid/Tetraethylammonium Bromide/Water: An Efficient Combination for Oxidative Cleavage of Acetals.

    CHEMINFORM, Issue 31 2009
    Chutima Kuhakarn
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    Dehydration of benzene through fluorine containing aromatic polyamide membrane by pervaporation

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008
    P. K. Gutch
    Abstract A series of soluble polyamides were synthesized by direct polycondensation of the 5- tert -butyl isophthalic acid with different diamines. Solution (20%) of the polymers in suitable solvents was used to cast the membranes. The membranes showed selectivity toward the benzene (Bz) in a mixture of Bz/water (H2O). Water affinity of the membrane was found to be lower than that of Bz. The polyamide incorporating hexafluoro isopropylidene moiety was promising for the dehydaration of Bz and breaking of Bz/H2O azeotrope. The polymers exhibited inherent viscosities, ranging from 0.40 to 0.92 dL/g and 10% weight loss in synthetic air up to 474C. Glass transition temperature measured by DSC and DMA reached up to 258C. The membranes were pale yellow in appearance having tensile strength up to 85 MPa, modulus of elasticity up to 2.6 GPa, and elongation at break up to 9.5%, depending upon the exact repeating unit structure. 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]


    Heteroarm Star Polystyrene- block -Poly(4-vinylpyridine): Multiple Morphologies in Dilute Solutions

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2008
    Chia-Hung Lin
    Abstract Synthesis and solution morphologies of four new heteroarm star polystyrene- block -poly(4-vinylpyridine) were studied. As the water content increased, a morphological transformation of heteroarm PS4 -P4VP4 from spheres to cylinders, vesicles, and large compound vesicles was observed. The morphology of PS4 -P4VP4 in the solvent mixture of DMF/water or 1,4-dioxane/water was spherical, but changed to large compound micelles in THF/water. As the P4VP molar ratio decreased, the morphology changed from spherical mixed with cylindrical to vesicles, giant vesicles, and then to LCMs. The present study demonstrated the formation of multiple morphologies through manipulating solvent polarity and block ratio in dilute solution. [source]


    Structural Study on Water-induced Phase Transitions of Poly(ethylene imine) as Viewed from the Simultaneous Measurements of Wide-Angle X-ray Diffractions and DSC Thermograms

    MACROMOLECULAR SYMPOSIA, Issue 1 2006
    Tomoko Hashida
    Abstract Thermal behavior of poly(ethylene imine) [PEI] has been studied using simultaneous WAXD/DSC measurement system. PEI exhibits water-induced and thermally-induced phase transitions among four kinds of crystalline hydrates: anhydrate (EI/water,=,1/0), hemihydrate (1/0.5), sesquihydrate (1/1.5), and dihydrate (1/2). The chain conformation changes from a double helix in the anhydrate to a planar zigzag form in the three hydrates. The anhydrate melts at 60,C while the hydrates melt differently in the temperature region of 70,110,C. By means of the simultaneous WAXD/DSC measurements, complex DSC thermograms of PEI hydrates were characterized on the basis of X-ray diffractions obtained concurrently. [source]


    The structural organization in aqueous solutions of ionic liquids

    AICHE JOURNAL, Issue 1 2009
    Xiao 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]


    A Novel and Efficient System of a Visible-Light-Responsive Organic Photoelectrocatalyst Working in a Water Phase

    CHEMPHYSCHEM, Issue 5 2004
    Toshiyuki Abe Prof.
    The best of both worlds: An organic bilayer, composed of a perylene derivative (PV) and a phthalocyanine (H2Pc), was found to be a novel example of a photoanode involving a catalytic oxidation in water (see graphic). Based on the action spectrum for photocurrent, it is noted that the widespread visible light absorption (<750 nm) by only the PV can efficiently induce the photoanodic current generation at the interface of H2Pc/water coupled with the hole-conducting character of H2Pc. [source]


    Investigation of p-type macroporous silicon formation

    PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2005
    C. Lvy-Clment
    Abstract Nanopores and macropores can be formed electrochemically on p-type silicon depending on the silicon resistivity and composition of the electrolyte. In order to understand if the structural dimensionality of the porous p-type Si, either nanopore or macropore formation, depends on the electrochemical process at the Si/electrolyte interface, in situ pulsed surface photovoltage (SPV) and photoluminescence (PL) measurements have been undertaken. The SPV and PL studies have been made as a function of the applied current density as well as the electrolyte composition (aqueous or in presence of organic solvent) and the silicon doping density. Main results show that the Si surface is well passivated with preferential formation of ionic species and the Si band bending is around 100 mV, during porous Si formation. It varies slightly with the doping density, but is not affected by the composition of the electrolyte (HF/water and HF/organic solvent). This demonstrates that the chemistry of the electrolyte plays a major role in the formation of macroporous and nanoporous Si, but has still to be determined. ( 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Drug,Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water, and Octan-1-ol/Water Systems

    HELVETICA CHIMICA ACTA, Issue 2 2010
    Xiangli 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]


    Ionic Liquid/Water as a Recyclable Medium for Tsuji,Trost Reaction Assisted by Microwaves.

    CHEMINFORM, Issue 36 2005
    Meng-chun Liao
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]


    Guest,Guest,Host Multicomponent Molecular Crystals: Entrapment of Guest,Guest in Honeycomb Networks Formed by Self-Assembly of 1,3,5-Tri(4-hydroxyaryl)benzenes

    CHEMISTRY - A EUROPEAN JOURNAL, Issue 26 2010
    Jarugu, Narasimha Moorthy Prof.
    Abstract Sterically-engineered rigid trigonal molecular modules based on 1,3,5-tri(4-hydroxyphenyl)benzenes H1 and H2 undergo O-H,,,O hydrogen-bonded self-assembly into eight-fold catenated hexagonal (6,3) and two-fold interpenetrated undulated square (4,4) networks, respectively. In the presence of [18]crown-6 as a guest, the triphenol H1 is found to self-assemble into a honeycomb network with hexagonal voids created between three triphenol building blocks. The guest [18]crown-6 molecules are found to be nicely nested in hexagonal enclosures. The empty spaces within the crowns can be further filled with neutral (MeOH/water, MeOH/MeNO2) or ionic guest species such as KI/KAcAc to furnish novel multicomponent assemblies, that is, guest,guest,host, that typify Russian dolls. In contrast, triphenol H2 is found to yield analogous multicomponent molecular crystals in which the guest crown,K+ acts as a spacers in the hydrogen-bonded self-assembly that leads to distorted chicken wire networks. [source]


    Helix Formation in Synthetic Polymers by Hydrogen Bonding with Native Saccharides in Protic Media

    CHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2006
    Minoru Waki
    Abstract Water-soluble poly(m -ethynylpyridine)s were designed to realize saccharide recognition in protic media. UV/Vis, 1H NMR, and fluorescence measurements revealed that the polymer forms a helical higher order structure by solvophobic interactions between the ethynylpyridine units in the protic medium. The resulting pore in the helix behaves like a binding pocket in proteins, by taking advantage of inwardly directed hydrogen-bonding functional groups of the polymers. Molecular recognition of native saccharides by the polymers was investigated by circular dichroism (CD). The chirality of the saccharide was transferred to the helical sense of the polymers, accompanied by the appearance of induced CDs (ICDs) in the absorptive region of the polymers. In MeOH/water (10/1), mannose and allose showed intense ICDs, and the apparent association constant between the polymer and D -mannose was 14,M,1. [source]


    HPLC determination of acidic d -amino acids and their N -methyl derivatives in biological tissues

    BIOMEDICAL CHROMATOGRAPHY, Issue 6 2009
    Mara Tsesarskaia
    Abstract d -Aspartate (d -Asp) and N -methyl- d -aspartate (NMDA) occur in the neuroendocrine systems of vertebrates and invertebrates, where they play a role in hormone release and synthesis, neurotransmission, and memory and learning. N -methyl- d -glutamate (NMDG) has also been detected in marine bivalves. Several methods have been used to detect these amino acids, but they require pretreatment of tissue samples with o -phthaldialdehyde (OPA) to remove primary amino acids that interfere with the detection of NMDA and NMDG. We report here a one-step derivatization procedure with the chiral reagent N-, -(5-fluoro-2,4-dinitrophenyl)-(d or l)-valine amide, FDNP-Val-NH2, a close analog of Marfey's reagent but with better resolution and higher molar absorptivity. The diastereomers formed were separated by HPLC on an ODS-Hypersil column eluted with TFA/water,TFA/MeCN. UV absorption at 340 nm permitted detection levels as low as 5,10 pmol. d -Asp, NMDA and NMDG peaks were not obscured by other primary or secondary amino acids; hence pretreatment of tissues with OPA was not required. This method is highly reliable and fast (less than 40 min HPLC run). Using this method, we detected d -Asp, NMDA and NMDG in several biological tissues (octopus brain, optical lobe and bucchal mass; foot and mantle of the mollusk Scapharca broughtonii), confirming the results of other researchers. Copyright 2009 John Wiley & Sons, Ltd. [source]


    Investigation of penetratin peptides Part 1.

    JOURNAL OF PEPTIDE SCIENCE, Issue 4 2002
    The environment dependent conformational properties of penetratin, two of its derivatives
    Abstract The homeodomain, the DNA-binding domain of Antennapedia homeoprotein, is composed of three ,-helices and one ,-turn between helices II and III. Its third helix from the N -terminal (helix III) can translocate through the cell membrane into the nucleus and can be used as an intracellular vehicle for the delivery of oligopeptides and oligonucleotides. To the best of our knowledge, this helix III, called penetratin, which consists of 16 amino acids, is internalized by cells in a specific, non-receptor-mediated manner. For a better understanding of the mechanism of the transfer, the structure of penetratin was examined in both extracellular matrix-mimetic and membrane-mimetic environments; 1H-NMR and CD spectroscopic measurements were performed in mixtures of TFE/water with different ratios. The molecular conformations of two analogue peptides [(6,14-Phe)-penetratin and a 12 amino acid penetratin derivative (peptide 3)] were also studied. An atomic level comprehensive analysis of penetratin and its two analogues was performed. In a membrane-mimetic solvent system (TFEd2/water = 9 : 1), on the basis of 553 distance restraints, the 4,12 region of penetratin exhibits a bent, irregular helical structure on NMR examination. Interactions between hydrophobic amino acid residues in conjunction with H-bonds stabilize the secondary structure of the molecule. Thus, both derivatives adopt a helix-like conformation. However, while (6,14-Phe)-penetratin displays both ,-helical and 310 -helical features, the structure of peptide 3 is predominantly a 310 -helix. Of the three peptides, surprisingly (6,14-Phe)-penetratin has the largest helical content. An increase in the polarity of the molecular environment gradually disintegrates these helix-like secondary structures. In a highly aqueous molecular system (TFEd2/water = 1 : 9), the fast exchange of multiple conformers leads to too few distance restraints being extracted, therefore the NMR structures can no longer be determined. The NMR data show that only short-range order can be traced in these peptides. Under these conditions, the molecules adopt nascent helix-like structures. On the other hand, CD spectra could be recorded at any TFE/water ratio and the conformational interconversion could therefore be monitored as a function of the polarity of the molecular environment. The CD data were analysed comprehensively by the quantitative deconvolution method (CCA+). All three penetratin peptides display helical conformational features in a low dielectric medium, with significant differences as a function of their amino acid composition. However, these conformational features are gradually lost during the shift from an apolar to a polar molecular environment. Copyright 2002 European Peptide Society and John Wiley & Sons, Ltd. [source]


    Conformations of Betanova in aqueous trifluoroethanol,

    BIOPOLYMERS, Issue 10 2010
    Danny P. Chagolla
    Abstract Conformations of the designed peptide Betanova in 42% trifluoroethanol/water (v/v) were explored. Circular dichroism (CD) observations provided no evidence for the presence of significant amounts of ,-structures in water, in TFE/water, or in ethanol/water. Nuclear magnetic resonance (NMR) diffusion experiments showed no significant difference in the hydrodynamic radius of the peptide in water and in 42% TFE/water. However, calculations indicated that the hydrodynamic radii of the triple-stranded ,-sheet, originally proposed for Betanova by Kortemme et al. (Science 1998, 281, 253-256), and a variety of partially folded forms of Betanova would be similar and likely could not be convincingly distinguished by diffusion experiments. Temperature coefficients (,,/,T) of the peptide NH chemical shifts are similar in water and 42% TFE/water, implying that most of these protons are highly solvent exposed in both solvents and likely do not participate in intramolecular hydrogen bonding interactions. Possible exceptions to this conclusion are the Lys9 and Lys15 residues, where a more positive coefficient may indicate that these residues are involved to some extent in local turn structures. Peptide proton,solvent fluorine intermolecular nuclear Overhauser effect (NOE)s at 25C were consistent with the presence of a mixture of conformations, which could include the triple-stranded ,-sheet structure as a minor component. At 0C, peptide-TFE NOEs indicated that TFE interacts strongly enough with many protons of Betanova that alcohol-peptide interactions persist for times of the order of nanoseconds, appreciably longer than the encounter time characteristic of mutual diffusion of TFE and the solute. 2010 Wiley Periodicals, Inc. Biopolymers 93: 893,903, 2010. [source]


    Investigation of penetratin peptides Part 1.

    JOURNAL OF PEPTIDE SCIENCE, Issue 4 2002
    The environment dependent conformational properties of penetratin, two of its derivatives
    Abstract The homeodomain, the DNA-binding domain of Antennapedia homeoprotein, is composed of three ,-helices and one ,-turn between helices II and III. Its third helix from the N -terminal (helix III) can translocate through the cell membrane into the nucleus and can be used as an intracellular vehicle for the delivery of oligopeptides and oligonucleotides. To the best of our knowledge, this helix III, called penetratin, which consists of 16 amino acids, is internalized by cells in a specific, non-receptor-mediated manner. For a better understanding of the mechanism of the transfer, the structure of penetratin was examined in both extracellular matrix-mimetic and membrane-mimetic environments; 1H-NMR and CD spectroscopic measurements were performed in mixtures of TFE/water with different ratios. The molecular conformations of two analogue peptides [(6,14-Phe)-penetratin and a 12 amino acid penetratin derivative (peptide 3)] were also studied. An atomic level comprehensive analysis of penetratin and its two analogues was performed. In a membrane-mimetic solvent system (TFEd2/water = 9 : 1), on the basis of 553 distance restraints, the 4,12 region of penetratin exhibits a bent, irregular helical structure on NMR examination. Interactions between hydrophobic amino acid residues in conjunction with H-bonds stabilize the secondary structure of the molecule. Thus, both derivatives adopt a helix-like conformation. However, while (6,14-Phe)-penetratin displays both ,-helical and 310 -helical features, the structure of peptide 3 is predominantly a 310 -helix. Of the three peptides, surprisingly (6,14-Phe)-penetratin has the largest helical content. An increase in the polarity of the molecular environment gradually disintegrates these helix-like secondary structures. In a highly aqueous molecular system (TFEd2/water = 1 : 9), the fast exchange of multiple conformers leads to too few distance restraints being extracted, therefore the NMR structures can no longer be determined. The NMR data show that only short-range order can be traced in these peptides. Under these conditions, the molecules adopt nascent helix-like structures. On the other hand, CD spectra could be recorded at any TFE/water ratio and the conformational interconversion could therefore be monitored as a function of the polarity of the molecular environment. The CD data were analysed comprehensively by the quantitative deconvolution method (CCA+). All three penetratin peptides display helical conformational features in a low dielectric medium, with significant differences as a function of their amino acid composition. However, these conformational features are gradually lost during the shift from an apolar to a polar molecular environment. Copyright 2002 European Peptide Society and John Wiley & Sons, Ltd. [source]


    Heteroarm Star Polystyrene- block -Poly(4-vinylpyridine): Multiple Morphologies in Dilute Solutions

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 22 2008
    Chia-Hung Lin
    Abstract Synthesis and solution morphologies of four new heteroarm star polystyrene- block -poly(4-vinylpyridine) were studied. As the water content increased, a morphological transformation of heteroarm PS4 -P4VP4 from spheres to cylinders, vesicles, and large compound vesicles was observed. The morphology of PS4 -P4VP4 in the solvent mixture of DMF/water or 1,4-dioxane/water was spherical, but changed to large compound micelles in THF/water. As the P4VP molar ratio decreased, the morphology changed from spherical mixed with cylindrical to vesicles, giant vesicles, and then to LCMs. The present study demonstrated the formation of multiple morphologies through manipulating solvent polarity and block ratio in dilute solution. [source]


    THE LASTING SCIENTIFIC IMPACT OF THE THORNTHWAITE WATER,BALANCE MODEL

    GEOGRAPHICAL REVIEW, Issue 3 2010
    BARRY D. KEIM
    First page of article [source]


    SOCIAL CONSTRUCTION OF HYDROPOLITICS: THE GEOGRAPHICAL SCALES OF WATER AND SECURITY IN THE INDUS BASIN,

    GEOGRAPHICAL REVIEW, Issue 4 2007
    Daanish Mustafa
    ABSTRACT. The article identifies important themes and future research directions for analyzing water and conflict dynamics at the subnational scale in the Indus Basin. A historical overview of water development in the Indus Basin suggests that the water-security nexus was always a salient theme in the minds of water developers, even in the nineteenth century. Conflicts over contemporary large-scale water-development projects in the Indian and Pakistani parts of the Indus Basin are reviewed. Engineers' single-minded focus on megaprojects, to the neglect of the wider set of values that societies attach to water resources in the eastern and western Indus Basin are largely to blame for continuing low-grade conflict in the basin. A review of local-level conflicts over water supply and sanitation in Karachi and the distribution of irrigation water in Pakistani Punjab illustrates the critical role of governance and differential social power relations in accentuating conflict. The article argues against neo-Malthusian assumptions about the inevitability of conflict over water because of its future absolute scarcity. Instead, the article seeks to demonstrate that, despite evidence suggesting that international armed conflict over water does not exist, the potential for political instability over domestic water distribution and development issues is real. The question of whether conflict at the subnational scale will culminate in violence will depend on how water-resources institutions in the basin behave. [source]


    ROLE OF INITIAL MUSCLE pH ON THE SOLUBILITY OF FISH MUSCLE PROTEINS IN WATER

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2004
    STEPHEN D. KELLEHER
    The solubility of the myofibrillar and cytoskeletal proteins in water was determined for the muscle tissue often species offish. The flesh of six white-muscled fish had pH's at the time of processing above pH 6.6 and greater than 80% of their myofibrillar/cytoskeletal proteins were soluble in water. The flesh of three pelagic species and a shark had pH values when processed below 6.6 and the water solubility of their myofibrillar and cytoskeletal proteins was less than 40%. When the washed minced muscle of one of the white-fleshed species, cod, was exposed to low pH, the solubility of its myofibrillar and cytoskeletal proteins decreased substantially. The water solubility of the cod myofibrillar and cytoskeletal proteins could be reestablished by washing the acid-treated cod flesh with neutral salt solutions. It is suggested that pH values below 6.6 modify certain proteins which prevent the water-extractability of the rest of the myofibrillar and cytoskeletal proteins from being expressed. [source]


    MICROBIAL, CHEMICAL AND PHYSICAL CHANGES IN CHILL WATER TREATED WITH ELECTROCHEMICAL METHOD

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2000
    LI MA
    ABSTRACT A three-zone (anode, neutral, and cathode) electrochemical treatment chamber was designed and built to evaluate the inactivation of Salmonella typhimurium in poultry chill water. The chill water in the three-zone chamber containing ,106 CFU/mL S. typhimurium and 0.5% or 1.0% NaCl was treated at 15 or 25 mA/cm2, and a temperature of 5,10C for up to 10 min. The Salmonella were inactivated within 0.5 to 4 min in the anode zone depending on the salt concentration and current density, slower inactivation rate in the cathode zone, and almost no inactivation in the neutral zone. The pH decreased to , 2 in anode zone, but increased to , 10 in the cathode zone. Temperature increased by 2,6.5C in the three zones depending on current density and salt concentration. The conductivity increased in the anode and cathode zones but little change in the neutral zone. The generated chlorine was proportional to the current density and the treatment time. [source]


    MOISTURE SORPTION ISOTHERM, PROPERTIES OF SORBED WATER AND HEAT OF SORPTION OF SANDESH, AN INDIAN MILK PRODUCT

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2010
    J.K. SAHU
    ABSTRACT Moisture sorption isotherm of sandesh, one of the most popular milk products in India, was determined in terms of its moisture adsorption isotherms by gravimetrical method at 20 and 30C using various saturated salt solutions in the range of 11.2 to 97.2%. The isotherms obtained were of sigmoid shape and of the Brunauer,Emmett,Teller type. Out of three sorption models fitted to the experimental data, Caurie's model was found superior in interpreting the moisture adsorption characteristics of sandesh. The monolayer moisture content as calculated from the Caurie's model at 20 and 30C were 5.89% (dry basis [d.b.]) and 5.21% (d.b.), respectively. The values of isosteric heat of sorption as calculated from Clausius,Clapeyron equation was found to increase with decreasing moisture content at lower moisture content and approached the value of heat of vaporization of free water above 17.25% (d.b.). PRACTICAL APPLICATIONS The present paper describes basically the storage stability of sandesh. The sandesh is a heat,acid coagulated product of milk in Indian subcontinent and forms the part and parcel of social life, ceremonies and festivals. It has an excellent market potential and higher profit margin compared with other milk products like table butter, cheese and milk powder. Although Indian dairy industry has made rapid strides in the last few decades, there is no proper packaging system, developed so far, for storage of sandesh. Keeping pace with the growing consumers' demand for fresh, convenient and microbiologically free foods, design of proper packaging system is the need of the hour. The data presented in the paper will be very much essential for the researchers and research and development institutions for proper designing of packaging system for sandesh. [source]


    COMPARISON OF ANOLYTE AND CHLORINATED WATER AS A DISINFECTING DIPPING TREATMENT FOR STORED CARROTS

    JOURNAL OF FOOD QUALITY, Issue 6 2003
    TILAHUN SEYOUM WORKNEH
    Packages of carrots were stored at 1 0.5C and ambient temperature (17.5,31.4C). The anolyte water dipping treatment was found to be as effective as chlorinated solutions in controlling growth of aerobic bacteria, molds, yeasts and coliform bacteria during storage. There were no significant differences (P < 0.05) in microbiological changes on carrots dipped in anolyte water for 5, 10, and 20 min. Exposure of carrots to anolyte water for as short as 5 min can be used effectively to reduce and limit growth of aerobic bacteria, molds, yeasts and coliform bacteria. Losses in firmness and physiological weight were higher in carrots dipped in chlorinated water. Anolyte water treatments had no effect on total soluble solid content, pH value, firmness and the overall visual appearance of carrots. [source]


    ASSESSMENT OF A WASH TREATMENT WITH WARM CHLORINATED WATER TO EXTEND THE SHELF,LIFE OF READY,TO,USE LETTUCE

    JOURNAL OF FOOD QUALITY, Issue 3 2003
    J.A. ODUMERU
    There was a significant difference in psychrotrophic counts (P<0.0001) of warm chlorine (100 ppm) washed lettuce at 47 2C for 30 s, 60 s, and 180 s exposure from days 1 to 10 of storage at 4C compared with cold chlorine (100 ppm) washed lettuce at 4 1C for 30 s. There were no significant differences in psychrotrophic counts between wash treatments of 30 s and 60 s during 17 days storage (P < 0.05). The EN detected initially high levels of volatiles in this group compared with cold treatment. Lettuce samples treated with cold or warm chlorine wash water showed no differences in the presence/absence or levels of Listeria monocytogenes. The warm chlorine washed lettuce samples were rated acceptable upon sensory evaluation up to day 14. [source]