bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gradient HPLC in the determination of drug lipophilicity and acidity
Authors: Kaliszan Roman , Haber Piotr , Baczek Tomasz , Siluk Danuta 
Published: October 2007

Abstract
The linear-solvent strength (LSS) model of gradient elution in high-performance liquid chromatography (HPLC) has been demonstrated to provide parameters of lipophilicity and acidity of analytes. pKa and log kw values are determined in three gradient runs. The first two experiments use an aqueous buffered eluent with a wide-range organic modifier gradient at pH of buffer, providing suppression of ionization of the analyte. That experiment allows an estimate of contents of the organic modifier in the mobile phase (%B), producing requested retention coefficient, k, for the nonionized form of the analyte. The next experiment is carried out with the latter %B and a pH-gradient of the aqueous component of the eluent that is sufficient to overlap possible pKa value of the analyte. The initial pH of the buffer used to make the mobile phase is selected to insure that the analyte is in nonionized form. The resulting retention time allows an estimate of pKa in a solvent of the given %B.
The log kw parameter obtained correlated well with the corresponding value obtained by the standard procedure of extrapolation of retention data determined in a series of isocratic measurements. The correlation between log kw and the reference parameter of lipophilicity, log P, was very good for a series of test analytes. The values of pKa were found to correlate with the literature pKa data determined in water for a set of aniline derivatives studied.
Rational design and synthesis of homochiral azole antifungal agents
Authors: Botta Maurizio , Corelli Federico , Manetti Fabrizio , Mugnaini Claudia , Tafi Andrea 
Published: October 2007

Abstract
The first synthesis of both enantiomers of the antifungal drug bifonazole (1a) and related imidazole compounds 1i and 5b,c is described, starting from enantiomerically pure or enriched amines 6a­d. Construction of the imidazole ring on amines 6a­d was performed in a straightforward manner affording the final compounds in good overall yield and with very high enantiomeric purity, as determined by enantioselective HPLC. Biological evaluation in vitro of the single enantiomers of 1a,i and 5b,c against different strains of Candida albicans did not show any enantioselectivity. Finally, the pseudoreceptor modeling technique was applied to generate a model able to explain and predict the inhibitory activity of azole compounds against C. albicans P45014DM.
Combinatorial chemistry. Facing the challenge of chemical genomics
Authors: Darvas Ferenc , Dorman Gyorgy , Urge Laszlo , Szabo Istvan , Ronai Zsolt , Sasvari-Szekely Maria 
Published: October 2007

Abstract
In the age of high-throughput screening and combinatorial chemistry, the focus of drug discovery is to replace the sequential approach with the most effective parallel approach. By the completion of the human gene-map, understanding and healing a disease require the integration of genomics, proteomics, and, very recently, metabolomics with early utilization of diverse small-molecule libraries to create a more powerful "total" drug discovery approach.
In this post-genomic era, there is an enhanced demand for information-enriched combinatorial libraries which are high-quality, chemically and physiologically stable, diverse, and supported by measured and predicted data. Furthermore, specific marker libraries could be used for early functional profiling of the genome, proteome, and metabolome. In this new operating model, called "combinatorial chemical genomics", an optimal combination of the marker and high-quality libraries provides a novel synergy for the drug discovery process at a very early stage.
Capillary electrophoretic techniques toward the metabolome analysis
Authors: Terabe Shigeru , Markuszewski Michal J. , Inoue Naoko , Otsuka Koji , Nishioka Takaaki 
Published: October 2007

Abstract
Metabolome analysis is a systematic chemical analysis of metabolites, which may be used to investigate the metabolic activity in the cell. Capillary electrophoresis (CE) is one of the most promising techniques for the metabolome analysis, because it gives high-resolution separations in a reasonable time and requires a minimum amount of samples. General characteristics of CE are discussed from the viewpoint of metabolome analysis. Micellar electrokinetic chromatography (MEKC), a separation mode of CE, enables the separation of neutral analytes by using micelles as pseudostationary phases. MEKC is also powerful for the separation of ionic analytes to improve selectivity. To solve relatively poor concentration sensitivity with UV absorbance detection, on-line sample preconcentration techniques were developed resulting in up to few thousand-fold increases in sensitivity. Laser-induced fluorescence detection is another solution to increase concentration sensitivity, but most analytes are not natively fluorescent. Therefore, several derivatization reactions were performed to selectively detect a class of analytes with high sensitivity. Some preliminary results are shown with formic acid extracts of Bacillus subtilis.
Threading intercalation to double-stranded DNA and the application to DNA sensing. Electrochemical array technique
Authors: Takagi Makoto 
Published: October 2007

Abstract
Electrochemical labeling of double-stranded (ds) DNA is achieved by redox-active DNA intercalators. Threading intercalators derived from naphthalenediimide appended with ferrocene reporter group in the side arms are particularly useful for this purpose. This allows a sensitive electrochemical detection of DNA hybridization on an array, providing a great potential for low-cost, high-throughput, and quick DNA screening technique in post-genome study.
Selective detection of neurotransmitters by fluorescence and chemiluminescence imaging
Authors: Wang Ziqiang , Yeung Edward S. 
Published: October 2007

Abstract
In recent years, luminescence imaging has been widely employed in neurochemical analysis. It has a number of advantages for the study of neuronal and other biological cells: (1) a particular molecular species or cellular constituent can be selectively visualized in the presence of a large excess of other species in a heterogeneous environment; (2) low concentration detection limits can be achieved because of the inherent sensitivity associated with fluorescence and chemiluminescence; (3) low excitation intensities can be used so that long-term observation can be realized while the viability of the specimen is preserved; and (4) excellent spatial resolution can be obtained with the light microscope so subcellular compartments can be identified. With good sensitivity, temporal and spatial resolution, the flux of ions and molecules and the distribution and dynamics of intracellular species can be measured in real time with specific luminescence probes, substrates, or with native fluorescence. A noninvasive detection scheme based on glutamate dehydrogenase (GDH) enzymatic assay combined with microscopy was developed to measure the glutamate release in cultured cells from the central nervous system (CNS). The enzyme reaction is very specific and sensitive. The detection limit with CCD imaging is down to mM levels of glutamate with reasonable response time. We also found that chemiluminescence associated with the ATP-dependent reaction between luciferase and luciferin can be used to image ATP at levels down to 10 nM in the millisecond time scale. Similar imaging experiments should be feasible in a broad spectrum of biological systems.
Ultrafast dynamics at solid/liquid interfaces as investigated by photothermal spectroscopy
Authors: Sawada Tsuguo 
Published: October 2007

Abstract
Among the recent topics of photothermal (PT) applications of lasers, we focus on ultrafast (&lt;=1.0 ns) photothermal/photoacoustic (PT/PA) phenomena occurring at interfaces, which play important roles in nanoscale materials science and technology. Here, we describe our recently developed novel PT techniques called transient reflecting grating (TRG) spectrometries. These techniques have been applied to the studies of solid surfaces, film substrates, and solid/liquid interfaces.
Standards in isothermal microcalorimetry (IUPAC Technical Report)
Authors: Wadsö Ingemar , Goldberg Robert N. 
Published: October 2007

Abstract
The main calorimetric principles used in isothermal microcalorimetry are briefly discussed. Different chemical calibration and test reactions are discussed, with a focus on reactions suitable for ambient conditions: reactions initiated by mixing of liquids (including titration microcalorimetry), dissolution of solid compounds and of slightly soluble gases, a photochemical process, and thermal power signals released over an extended period of time. Guidelines on the use of standardized chemical test and calibration reactions in isothermal microcalorimetry are presented. A standardized terminology in reporting characteristics of isothermal microcalorimeters is proposed.
Critical evaluation of stability constants of phosphonic acids (IUPAC Technical Report)
Authors: Popov Konstantin , Rönkkömäki Hannu , Lajunen Lauri H. J. 
Published: October 2007

Abstract
Available experimental data on stability constants of proton and metal complexes for 10 phosphonic acids [methylphosphonic acid, 1-hydroxyethane-1,1-diylbisphosphonic acid, dichloromethylenebisphosphonic acid, amino-methanephosphonic acid, N-(phosphonomethyl)glycine, imino-N,N-bis(methylenephosphonic acid), N-methylamino-N,N-bis(methylenephosphonic acid), nitrilotris(methylenephosphonic acid), 1,2-diaminoethane-N,N,N´,N´-tetrakis-(methylenephosphonic acid), and diethylenetriamine-N,N,N´,N´´,N´´-pentakis-(methylenephosphonic acid)], published in 1950­1997, have been critically evaluated. For the latter phosphonate, all the data are rejected, as well as protonation constants [HL]/[H][L] for three other ligands. Higher-quality data are selected and presented as "Recommended" and "Provisional".
Theories of structural and dynamic properties of ions in discrete solvents. Application to magnetic resonance imaging
Authors: Fries Pascal H. , Richardi Johannes , Rast Sebastian , Belorizky Elie 
Published: October 2007

Abstract
The molecular Ornstein­Zernike (MOZ) formalism used to compute the structure of a liquid solution is briefly presented. Its ability to describe the equilibrium properties of aprotic solvents and of their electrolyte solutions is demonstrated from selected examples. The potential of mean force and the relative motion of ions in water are studied by the powerful method of intermolecular nuclear magnetic relaxation dispersion (NMRD) in paramagnetic solutions. The interest of the ion­ion dynamics in medical magnetic resonance imaging (MRI) is shown by a typical NMRD study involving paramagnetic gadolinium Gd3+ complexes.
Using simulation to study solvation in water
Authors: Lynden-Bell R. M. , Rasaiah J. C. , Noworyta J. P. 
Published: October 2007

Abstract
Simulations of simple solutes (charged and uncharged spheres) in model water have been performed in order to elucidate aspects of solvation in water at ambient and supercritical states. The variation of solvation entropy as a function of solute charge has been used to investigate hydrophobic and hydrophilic ordering and the structure-making and structure-breaking effects of ions. Simulations with model solvents, which differ from water in certain features, have been used to try to identify the particular properties of water that are associated with these phenomena.
Corresponding states for electrolyte solutions
Authors: Weingärtner Hermann 
Published: October 2007

Abstract
The equilibrium properties of electrolyte solutions over wide ranges of concentration, temperature, and solvent dielectric constant are discussed on a corresponding-states basis. If low-melting salts are used, these properties can be studied up to the pure fused salt. We mainly focus on systems at low reduced temperature, where the depth of the interaction potential is large compared with the thermal energy. Examples are singly charged ions in solvents of low dielectric constant and of highly charged ions in water. The state of the ions is discussed on the basis of thermodynamic, electrical conductance and dielectric constant data. Special attention is given to the transition to the fused salt, where ion clusters have to redissociate to form the dissociated structure of the salt. This transition can lead to liquid­liquid phase separations. The resulting critical points serve as important targets for testing theories. Examples are given for large deviations from corresponding-states behavior caused by specific short-range interactions.
Molality-based primary standards of electrolytic conductivity (IUPAC Technical Report)
Authors: Pratt K. W. , Koch W. F. , Wu Y. C. , Berezansky P. A. 
Published: October 2007

Abstract
New values of electrolytic conductivity were determined for aqueous KCl solutions with molalities of 0.01, 0.1, and 1.0 mol/kg in the temperature range 0 to 50 °C, at 5 K intervals. Expanded uncertainties, 2u
c, were also calculated in accordance with the presently accepted protocol for the treatment of uncertainty. The new conductivity values are recommended as primary standards of electrolytic conductivity based on molality. They replace the previous values, based on the nonstandard demal scale, which were determined only at 0, 18, and 25 °C. The accuracy of the technique used was evaluated by repeating the determination of the previously recommended demal-based IUPAC standards of electrolytic conductivity and through comparison with other absolute measurements.
Electrochemical technology for environmental treatment and clean energy conversion
Authors: Walsh F. C. 
Published: October 2007

Abstract
The applications of electrochemical technology in environmental treatment, materials recycling, and clean synthesis are briefly reviewed. The diversity of these applications is shown by the number of industrial sectors involved. The scale of operation ranges from microelectrodes to large industrial cell rooms. The features of electrochemical processes are summarized.
Available and developing electrode designs are considered and illustrated by examples including the regeneration of chromic acid electroplating baths, metal ion removal by porous, 3-dimensional cathodes, rotating cylinder electrodes (RCEs), and a reticulated vitreous carbon (RVC) RCE. The use of performance indicators based on mass transport, electrode area, and power consumption is emphasized.
Electrochemical reactors for energy conversion are considered, with an emphasis on load-leveling and proton-exchange membrane (PEM) (hydrogen­oxygen) fuel cells. Ion-exchange membranes play an essential role in such reactors, and the variation of electrical resistance vs. membrane thickness is described for a series of extruded, Nafion® 1100 EW materials. The characterization of high-surface-area, platinized Nafion surfaces is also considered. The development of modular, filter-press cells as redox flow cells in electrical load-leveling applications is concisely described.
Trends in electrode, membrane, and reactor design are highlighted, and the challenges for the development of improved reactors for environmental treatment are noted.
Green processes for environmental application. Electrochemical ozone production
Authors: Da Silva L. M. , De Faria L. A. , Boodts J. F. C. 
Published: October 2007

Abstract
Several aspects of electrochemical ozone production (EOP) on b-PbO2 were investigated. The morphology of the electrode material was determined in situ using extensive (total, external, and internal differential capacity) and intensive parameters (the morphology factor, j) permitting comparison with results of other laboratories if appropriate electrode characterization parameters are available. The influence of the nature of the supporting electrolyte on the oxygen evolution reaction (OER)/EOP processes was investigated using polarization curves, recorded under quasi-stationary conditions, point-by-point polarization, and chronopotentiometry. The performance of the several b-PbO2/electrolyte system was evaluated using the apparent specific power criterion. A detailed mechanism for EOP is proposed.
Direct electrochemistry of nanoparticulate Fe2O3 in aqueous solution and adsorbed onto tin-doped indium oxide
Authors: McKenzie Katy J. , Marken Frank 
Published: October 2007

Abstract
Nanoparticulate iron oxides occur naturally, for example, in soil, water, and in the cytoplasm of living cells. The redox properties and detection of these nanoparticles are therefore of considerable importance. Understanding and mimicking nanoparticle-based redox reactions may lead to new types of water-based electrochemical processes. In this study, the electrochemical detection of 4­5 nm diameter Fe2O3 nanoparticles dissolved in aqueous buffer solutions is investigated as a model system.
Voltammetric experiments with nanoparticulate Fe2O3 are reported based on two complementary approaches: (i) Fe2O3 nanoparticles adsorbed onto tin-doped indium oxide (ITO) electrodes are shown to give well-defined voltammetric reduction responses and (ii) hydrodynamic voltammety in the presence of fast (24 kHz ultrasound-enhanced) mass transport is shown to allow the direct detection of Fe2O3 nanoparticles in solution. Both the adhesion and the electrochemical reactivity of Fe2O3 nanoparticles at ITO electrode surfaces are strongly affected by the solution composition and the pH.
Green synthesis via electrolysis in microemulsions
Authors: Rusling James F. 
Published: October 2007

Abstract
Electrolysis in microemulsions is a promising approach for environmentally friendly chemical synthetic methods of the future. Employing microemulsions instead of organic solvents for electrosynthesis has the advantages of lower toxicity and cost, high dissolving power for reactants and mediators of unlike solubility, enhancement of reaction rates by controlling the reduction potentials of mediators, possible reaction pathway control, and recycling of microemulsion components. This paper reviews recent progress in using microemulsions for direct and mediated electrosynthesis, including formation of carbon­carbon bonds. Rates of mediated reactions can be controlled by manipulating microemulsion composition. Examples are presented, in which reaction pathways of direct and mediated electrolyses can be controlled with microemulsions to give desired products in high yields. Such control has been demonstrated with dissolved and surface-bound mediators. For a covalently linked scaffold of poly(l-lysine) and cobalt corrin vitamin B12 hexacarboxylate attached to graphite, catalytic turnover rate for reduction of 1,2-dibromocylcohexane was optimized by optimizing microemulsion composition.
Status of organochlorine (DDT) pollutants and steps toward electrocatalytic reductions
Authors: Kiflom Welderufael G. , Wandiga Shem O. , Kamau Geoffrey N. 
Published: October 2007

Abstract
The accumulation of DDT in the environment over the years is a major concern in the world today. The extent to which DDT may be absorbed and translocated from 14C-p,p¢-DDT contaminated soils into cowpea plant tissues, and the variation of uptake of p,p¢-DDT by the plants in relation to the dissipation of p,p¢-DDT in the soils was studied using a radioisotope technique. Significant absorption and accumulation of residues was observed for the cowpeas grown in two different sites, coastal and highland regions. The degree of uptake varied with soil type and growing conditions. Further results indicated that the higher the water retention by the soil the higher the rate of evaporation of p,p¢-DDT. Coastal region p,p¢-DDT soil samples showed DDE to be the major metabolite. DDT residue in the plants ranged from 0.94 to 7.73 mg/kg, while that in the soils ranged from 88.9 to 32.0 mg/kg. Preliminary electrode reactions indicated lowering of overpotential for reduction of p-chlorophenol by about 1 V, using copper phthalocyanine tetrasodium tetrasulfonate as the catalyst in microemulsion. Microemulsions and appropriate catalysts are a promising system for the decomposition of DDT.
Electrochemical approaches to alleviation of the problem of carbon dioxide accumulation
Authors: Sánchez-Sánchez C. M. , Montiel V. , Tryk D. A. , Aldaz A. , Fujishima A. 
Published: October 2007

Abstract
The electrochemical reduction of CO2, which includes a number of different specific approaches, may show promise as a means to help slow down the accumulation of this greenhouse gas in the atmosphere. Two types of approaches are examined briefly here. First, CO2 can be used as a reagent in the electrocarboxylation reaction to produce organic carboxylic acids, for example, the pharmaceutical ibuprofen. Second, CO2 can be converted to a fuel, either directly or via synthesis gas. The latter can be produced with reasonably good energy efficiency in a gas-diffusion, electrode-based cell even at present with existing electrocatalysts. Oxygen gas is produced as a by-product. Further work is needed to improve the selectivity and efficiency in this and other approaches.
Oxidation of chlorophenols on Pt electrode in alkaline solution studied by cyclic voltammetry, galvanostatic electrolysis, and gas chromatography­mass spectrometry
Authors: Ezerskis Z. , Jusys Z. 
Published: October 2007

Abstract
Potentiodynamic investigations on a platinum electrode show that oxidation of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol in 1 M NaOH solution, containing 1 mM of phenols, proceeds in the potential region of Pt oxide formation. The oxidation rate of phenols decreases with the increase in the number of chlorine atoms in the benzene ring in the row: phenol > monochlorophenols > dichlorophenols > trichlorophenols > pentachlorophenol. The electrochemical stability of phenols, as studied using a cyclic voltammetry, depends on their chlorination degree and isomerism.
Galvanostatic oxidation of 1 M NaOH solutions containing 1 mM of phenol, monochlorophenols, dichlorophenols, 2,3,6-, 2,4,5-, 2,4,6-trichlorophenols, and pentachlorophenol were carried out on a platinum electrode using 30 mA cm­2 current density. The electrolysis of the solutions was performed in the course of 10 h, and concentration of phenols in the anolytes was monitored during oxidation. The concentration of phenolic compounds diminishes from 1 mM to 10­50 mM during 4­5 h of electrooxidation and does not change during further galvanostatic oxidation.
A decrease in concentration of phenols during galvanostatic electrolysis weakly depends on the isomerism and a chlorination degree of the compounds. A rapid decrease in concentration of studied phenols during the first 4­5 h of electrolysis and a nonselective oxidation of different chlorophenols suggest that the oxidation proceeds via electrochemically generated oxidants. Further decrease in concentration of phenols is rather small due to deactivation of the electrode as a result of polymerization of corresponding phenols and diffusion limitations.
Biphasic sonoelectrosynthesis. A review
Authors: Wadhawan Jay D. , Marken Frank , Compton Richard G. 
Published: October 2007

Abstract
Electrosynthesis can be carried out in emulsions formed in situ via sonication of otherwise immiscible liquid/liquid systems. The basic physical principles underlying these experiments are introduced and illustrated via three examples: the electroreduction of liquid olefins, the Kolbe electrooxidation, and the electrogeneration of leuco-methylene green.