bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resource inflows and household composition: evidence from South African panel data
Authors: Maitra Pushkar , Ray Ranjan 
Published: November 2003

AbstractEconomic analysis of household behaviour, usually, assumes that household size and composition are fixed and exogenous. This study departs from this practice by analysing resource and household compositional variables, using an interdependent framework that treats them as jointly endogenous. The study is conducted using panel data set of Black households residing in Kwazulu Natal province in South Africa. The results provide evidence of fluidity of household structure, and point to new hypotheses on the effects of household resources on household composition. Copyright © 2003 John Wiley & Sons, Ltd.
Transnational corporations and the discourse of water privatization
Authors: Robbins Peter T. 
Published: November 2003

AbstractFaced with a well‐documented fresh water crisis in many parts of the world, international institutions are advocating market‐based solutions involving the privatization and commodification of water. The definition of water as a commodity by multilateral organizations in the early 1990s allowed a handful of transnational corporations, supported by the World Bank and the IMF, to become centrally involved in management of public water services in poorer countries. The years 2000 to 2003 saw the retreat of TNC investment in water due to national economic crises, social protest, and the difficulties of extracting profit delivering water to indigent consumers. This article examines the shift in discursive strategy of development organizations, and the resulting rise and fall of TNC involvement in water and sanitation provision in the Third World. Copyright © 2003 John Wiley & Sons, Ltd.
Preparative isolation and characterization of zinc dialkyldithiophosphates from commercial antiwear additives
Authors: Carbognani Lante 
Published: November 2003

AbstractAn automated HPLC separation methodology was developed for the preparative separation of ZnDTP components from commercial lubricant antiwear additives. Using silica columns that can be reactivated by elution with appropriate solvents, gram quantities of additives can be isolated. The isolated materials are useful for carrying out further mechanistic and synthetic studies. Preliminary estimations suggest that separation repeatability and fraction recoveries have acceptable levels. Qualitative characterization of isolated ZnDTP mixtures was achieved by IR, TLC‐FID, and RP‐HPLC. IR is useful for assessing the nature of ZnDTP alcoholic moieties. TLC‐FID provides a check on the preparative HPLC separation efficiency. RP‐HPLC on octadecylsil‐silica columns provides fingerprints for isolated commercial ZnDTP active concentrates. Fingerprinting on small bore HPLC columns proved advantageous compared with conventional columns.
Enhancing the sensitivity of capillary electrophoresis using a microcolumn solid phase extraction setup
Authors: Zhang Pudun , Xu Guowang , Xiong Jianhui , Zheng Yufang , Shi Xianzhe , Yang Qing , Wei Fusheng 
Published: November 2003

AbstractIn this paper, a setup called micro‐column solid phase extraction (MicroSPE) was developed to enhance the sensitivity of capillary electrophoresis. The setup consists of a manual pump, several insulin syringes, and a Teflon extraction cartridge. The cartridge was made of 2–4 mm irregular C18 solid phase materials in a Teflon tube (375 μm ID) with glass fiber frits. Two pieces of capillary tubing were connected to both the ends of the cartridge. Using sulindac‐spiked urine as the test sample, the extraction and analytical conditions were investigated in detail. When 1 μL 70/30 methanol/water was applied as the elution solvent, satisfactory results could be obtained. The internal standard method was used to quantitatively determine the compound in urine. The detection limit for sulindac was 2.9 ng/mL and the enrichment factor reaches more than 260. The result illustrates that the MicroSPE setup has a significant concentrating effect and is suitable for preconcentrating and cleaning‐up samples with complex matrices.
Direct separation and quantitative determination of glimepiride isomers by high performance liquid chromatography
Authors: Song Yaru , Niu Liping , Wang Defa , Hu Yuping , Hou Dongyan 
Published: November 2003

AbstractA simple and sensitive high‐performance liquid chromatographic procedure for the determination of the trans isomer of glimepiride is reported. Chromatography accomplished direct separation of the cis and trans isomers of glimepiride on a Dikmonsil C18 (250×4.6 mm, 5 μm) column with a mobile phase consisting of methanol‐acetonitrile‐NH4Ac buffer solution (1.5 mol L–1, pH = 4.5) (1.1 : 1.3 : 1.0, v/v) at a flow rate 0.5 mL min–1. The resolution (RS) was 1.73 with a retention time of 24.885 and 23.018 min for the cis and the trans isomer, respectively. A standard linear calibration curve was established for the trans isomer of glimepiride over the range of 4.95–198.00 μg mL–1 with a correlation coefficient of 0.99997. This method has been successfully used to analyze four different kinds of glimepiride product.
Capillary electrochromatography with bare silicas of different pore sizes as stationary phases
Authors: Steiner Frank , Lobert Thorsten 
Published: November 2003

AbstractBare silica can be used with reversed phase eluents for the chromatographic separation of basic analytes. It provides high surface charge density within a certain pH range, thus generating a high electroosmotic flow (EOF) when applied in electrochromatography. The influence of pore size on EOF velocity and mass transport is demonstrated. High EOF and fast mass transfer were encountered with 100 nm and 200 nm material and related to a pore perfusion mechanism. On a silica with 200 nm average pore size at pH 7, an EOF velocity of 2 mm/s was obtained at 600 V/cm. Silicas with pore diameters between 6 nm and 200 nm, corresponding to surface areas between 500 m/g and 10 m/g (data calculated from inverse size exclusion chromatography experiments), were used for CEC and HPLC separation of strongly basic solutes. On separation of tricyclic antidepressants by CEC, “normal” and “abnormal” efficiencies were achieved and were found to vary with the charge density within the separation column.
Determination of new pyridoquinoline derivatives and their quantification in urine by capillary liquid chromatography
Authors: Srbek Jan , Coufal Pavel , Tesařová Eva , Bosáková Zuzana , Suchánková Jana 
Published: November 2003

AbstractCapillary liquid chromatography (CLC) in reversed separation mode was applied to the quantification and impurity profile determination of eight newly synthesized pyridoquinolines. The CLC separation system consisted of Nucleosil C18 stationary phase and methanol containing 1% (v/v) of triethylamine (TEA) as the mobile phase. The optimized separation system enabled the separation of impurities from the main component and their quantification in a reasonable analysis time. The presence of TEA in the mobile phase greatly improved the peak shape and decreased the analysis time of the studied derivatives on the C18 stationary phase. Calibration curves of pyridoquinolines were plotted in a concentration range from 1.0×10–6 to 1.0×10–3 mol/L at two parallel detector wavelengths of 254 and 265 nm and subsequently used for quantification of pyridoquinoline derivatives in human urine. No pretreatment of the real biological sample was needed. Detection and quantification limits were calculated for all the derivatives and the detection limits of most of the pyridoquinolines were found to lie in the μmol/L concentration range. The proposed CLC separation system has proved to be a suitable method for quantification of test derivatives in samples containing human urine matrix.
Cyclodextrin derivatives in enantiomer GC separation of volatiles. Part XXI: Complexation of some terpenoids with 2‐O‐acetyl‐3‐O‐methyl‐ and 2‐O‐methyl‐3‐O‐acetyl‐6‐O‐t‐hexyldimethylsilyl‐γ‐cyclodextrins: Molecular Mechanics and Molecular Dynamics
Authors: Bicchi Carlo , Brunelli Claudio , Cravotto Giancarlo , Rubiolo Patrizia , Galli Mario , Mendicuti Francisco 
Published: November 2003

AbstractMolecular Mechanics and Molecular Dynamics calculations were performed to simulate the 1 : 1 complex formation of 2‐O‐acetyl‐3‐O‐methyl‐ and 2‐O‐methyl‐3‐O‐acetyl‐6‐O‐t‐hexyldimethylsilyl‐γ‐cyclodextrins with a group of monoterpenoids having the p‐menthane skeleton (menthol, i‐menthol, neo‐menthol, neo‐i‐menthol, menthone, i‐menthone, and 3‐oxo‐1,8‐cineole) using nitrogen as simulated gas carrier. 1 : 1 complexes of the terpenoids studied are stable and non‐bonded van der Waals interactions are mainly responsible for complexation. The results suggest that the nature of the substituent (hydroxyl or oxo groups) at C3 on the cyclohexane ring, and its configuration for hydroxylated racemates, are responsible for the differences in complexation energies between the two investigated CD derivatives. This is in agreement with considerations of the difference in the experimental values of thermodynamic parameters, reported elsewhere, and may explain the difference in the enantioselectivity of the two CD derivatives for the terpenoids investigated. The substituents in position 1 are less involved in the chiral recognition process.
Structure‐enantioselectivity relationships for the study of chiral recognition in peptide enantiomer separation on cinchona alkaloid‐based chiral stationary phases by HPLC: Influence of the N‐terminal protecting group
Authors: Czerwenka Christoph , Lämmerhofer Michael , Lindner Wolfgang 
Published: November 2003

AbstractEleven different N‐terminal protecting groups (acetyl, benzoyl, FMOC, etc.) were employed for the HPLC separation of oligoalanine peptide enantiomers containing up to six amino acids. Isocratic HPLC separations were performed using a hydro‐organic buffered mobile phase and 4 mm ID columns containing three different chiral anion exchange stationary phases based on cinchona alkaloid‐derived chiral selectors. For most peptides successful separations could be obtained with all protecting groups, although those comprising aromatic moieties were found to yield higher enantioselectivities than those with aliphatic residues, since they are capable of undergoing favourable π‐π interactions with the selector. Systematic investigations concerning the presence or absence of structural features of related protecting groups showed that the use of protecting groups that are optimally adjusted to the binding pocket of the chiral selector effects a significant gain in enantioselectivity. At the same time these studies provided new insights into the chiral recognition mechanism.
Fast GC for the analysis of fats and oils
Authors: Mondello Luigi , Tranchida Peter Quinto , Costa Rosaria , Casilli Alessandro , Dugo Paola , Cotroneo Antonella , Dugo Giovanni 
Published: November 2003

AbstractFast and conventional GC techniques were both applied to ten different lipidic matrices and the results then compared. The fats and oils were of fish, animal, and vegetable origin and were all simultaneously transesterified with acidic methanol before performing batch analysis of the fatty acid methyl esters (FAMEs) obtained. All FAMEs samples were consecutively analyzed three times by each method. The fast method significantly reduced the time required for analysis by a factor of 5 while maintaining a similar resolution. Furthermore, the reproducibility of relative quantitative data was measured on going from one method to the other. Peak identification was achieved through conventional GC‐MS in combination with linear retention index values contained in a home library and information derived from comprehensive 2D GC group patterns.
Comparison of two sample clean‐up methodologies for the determination of polycyclic aromatic hydrocarbons in edible oils
Authors: Barranco Alejandro , Alonso‐Salces Rosa M. , Berrueta Luis A. , Gallo Blanca , Vicente Francisca , Sarobe Martin 
Published: November 2003

AbstractAn off‐line high‐performance normal‐phase liquid chromatography procedure with a silica column followed by reversed‐phase high‐performance liquid chromatography (HPLC) with fluorescence detection for the determination of polycyclic aromatic hydrocarbons (PAHs) in edible oils is reported. The method was validated using certified reference materials and compared with a standardized method widely used in the food industry, consisting in low pressure column chromatography with alumina as stationary phase followed by reversed phase HPLC determination. The limits of detection were lower than 1 ng/g and good selectivity was achieved for both methods. There were no significant differences in accuracies and precisions obtained for each approach. The advantages and disadvantages of the two methods are discussed.
Parameters Affecting the Lower Critical Solution Temperature of Linear and Crosslinked Poly(N‐ethylacrylamide) in Aqueous Media
Authors: Xue Wei , Huglin Malcolm B. , Jones Timothy G. J. 
Published: November 2003

AbstractA series of linear poly(N‐ethylacrylamide) (PEA) samples varying in molar mass has been prepared by free radical polymerization in the absence and presence of a chain transfer agent and a hydrogel of PEA has been prepared using N,N‐methylenebisacrylamide (BIS) as crosslinker. The lower critical solution temperatures (LCST) of the linear polymers in water and aqueous media were determined turbidimetrically as a function of molecular weight, concentration, heating/cooling rate, and concentrations of KCl and anionic surfactant sodium dodecyl sulfate (SDS) in the aqueous solution. The corresponding LCST for the hydrogel was determined from the gravimetric swelling ratios (r). In pure water the values of LCST for linear polymer and hydrogel are 73 °C and 62 °C, respectively. The LCST of linear PEA increases with decreasing molecular weight. The swelling ratio for gels and the LCST for solutions and gels increased with the inclusion of SDS into water. The opposite effects prevailed on inclusion of KCl into water or incorporation of crosslinker. Additionally, the rates of heating/cooling play a significant role in the measured value of LCST. Hence the swelling ratio of hydrogel or the LCST can be adjusted via 1) addition of either SDS or KCl into water; 2) use of different molecular weight samples; 3) incorporation of crosslinker into polymer chain.
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The Fabrication of Very Small Miniemulsion Latexes from N‐Stearoylglutamate and Lauryl Methacrylate: Evidence for Droplet Budding
Authors: Yildiz Ufuk , Landfester Katharina , Antonietti Markus 
Published: November 2003

AbstractA new, biodegradable surfactant with high efficiency, N‐stearoyl‐di(sodium)glutamate (SDG), was used for miniemulsion polymerization of styrene and lauryl methacrylate (LMA). In the case of styrene, SDG produces latexes at least as small as those produced by sodium dodecyl sulfate (SDS), over a range of concentrations. In the case of LMA, a combination of SDG with an appropriate costabilizer allows one to obtain very small particles. With potassium persulfate (KPS) as initiator, the SDG/LMA system deviates significantly from the ideal miniemulsion, forming extremely small particles, which was speculatively attributed to a budding phenomenon.The new, biodegradable surfactant, N‐stearoyl‐di(sodium)glutamate.magnified imageThe new, biodegradable surfactant, N‐stearoyl‐di(sodium)glutamate.
Synthesis and Characterization of Block Copolymers of ε‐Caprolactone and DL‐Lactide Initiated by Ethylene Glycol or Poly(ethylene glycol)
Authors: Huang Ming‐Hsi , Li Suming , Coudane Jean , Vert Michel 
Published: November 2003

AbstractBiodegradable copolymers were prepared by ring‐opening polymerization of sequentially added ε‐caprolactone and DL‐lactide in the presence of ethylene glycol or poly(ethylene glycol), using zinc metal as catalyst. Polymerization was performed in bulk and yielded block copolymers with predetermined PEG/PCL/PLA segments. The obtained polymers were characterized by 1H NMR, SEC, IR, DSC, TGA, and X‐ray diffraction. Data showed that the copolymers preserved the excellent thermal behavior inherent to PCL. The crystallinity of PLA‐containing copolymers was reduced with respect to PCL homopolymer. The presence of both hydrophilic PEG and fast degrading PLA blocks should improve the biocompatibility and biodegradability of the materials, which are of interest for applications as substrate in drug delivery or as scaffolding in tissue engineering.Block copolymerization of ε‐caprolactone and DL‐lactide initiated by dihydroxyl PEG.magnified imageBlock copolymerization of ε‐caprolactone and DL‐lactide initiated by dihydroxyl PEG.
Investigation of Templated Mesoporous Silicate Thin Films Using High Speed, Solid‐State 1H MAS and Double Quantum NMR Spectroscopy
Authors: Alam Todd M. , Fan Hongyou 
Published: November 2003

AbstractTwo‐dimensional DQ 1H MAS NMR has been used the investigate the local structure of a surfactant‐templated silicate thin film prepared from adding 4% polyoxyethylene(10) cetyl ether to an acidic TEOS silica sol. A close spatial contact between the surfactant and the silicate present in these materials could be demonstrated, while the high sensitivity of the NMR experiments allowed systems with limited amounts of material to be investigated. The detected inorganic‐organic interactions in these materials provide additional information into the chemical processes occurring during the self‐assembly process and the formation of meso‐structured materials.Graphical representation of the spatial interactions observed between the silanols, oxomethylene protons of the surfactant and water within the template silicate material.magnified imageGraphical representation of the spatial interactions observed between the silanols, oxomethylene protons of the surfactant and water within the template silicate material.
Versatile Synthesis of Soluble Multifunctional Thiophene Copolymers with NLO Activity
Authors: Costa‐Bizzarri Paolo , Lanzi Massimiliano , Paganin Luisa , Della‐Casa Carlo , Bertinelli Franco , Casalboni Mauro , Sarcinelli Felice , Quatela Alessia 
Published: November 2003

AbstractFunctionalized second‐order nonlinear optical (NLO) thiophene copolymers were synthesized. Two elegant syntheses based on the post‐functionalization of polymeric precursors obtained by oxidative polymerization were developed, leading to copolymers that proved to be fully soluble in common organic solvents. The new materials were characterized by NMR, FT‐IR, and UV‐vis spectroscopies, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Moreover, the NLO activity of the new materials, as determined by corona poling alignment and second harmonic generation (SHG) measurements, showed a good agreement between the second‐order NLO coefficient and the chromophore concentration.Three‐dimensional optimization of the chromophore thiophene‐functionalized comonomer.magnified imageThree‐dimensional optimization of the chromophore thiophene‐functionalized comonomer.
Effect of a Water‐Soluble Polymer on Polymer Interdiffusion in P(MMA‐co‐BA) Latex Films
Authors: Wu Jun , Winnik Mitchell A. , Farwaha Rajeev , Rademacher Jude 
Published: November 2003

AbstractWe describe non‐radiative energy‐transfer experiments to measure the rates of polymer interdiffusion in P(MMA‐co‐BA) latex films formed in the presence of poly(vinyl alcohol) (PVOH). PVOH had relatively little effect on the initial efficiency of energy transfer, even when the amount of PVOH was large enough to form the continuous phase. Since ΦET(0) is a measure of the interfacial area between D‐ and A‐labeled cells in the film, we conclude that under these circumstances the dispersed P(MMA‐co‐BA) copolymer is in the form of clusters with many contacts between particles containing D and A labels. These large amounts of PVOH also reduce the amount of polymer diffusion that takes place when the films are annealed. When smaller amounts of PVOH are present, the effects are measurable but much smaller. In the presence of 2 to 17 wt.‐% PVOH, the polymer diffusion rate is retarded. The magnitude of the effect increases with the amount of PVOH present, and the effect is larger at 45 °C than at 63 °C. We show that the PVOH has its largest influence at the very early stages of polymer diffusion.Schematic representation of an energy transfer experiment, which monitors polymer interdiffusion in a latex film.magnified imageSchematic representation of an energy transfer experiment, which monitors polymer interdiffusion in a latex film.
Propene Polymerisation with rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2 as a Highly Active Catalyst: Influence of Monomer Concentration, Polymerisation Temperature and a Heterogenising Support
Authors: Frediani Marco , Kaminsky Walter 
Published: November 2003

AbstractPropene was polymerised at high temperatures (up to 90 °C) using rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO as the catalytic system. The increasing deactivation reaction rate of the catalyst for polymerisations above 60 °C was less for a silica supported catalyst compared with the homogeneous one. The isotacticity of polypropene decreases from 99 to 96%. Also the morphology changes with different temperatures.Increasing of the thermal stability for the rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO/SiO2 with respect of the rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO system.magnified imageIncreasing of the thermal stability for the rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO/SiO2 with respect of the rac‐[Me2Si(2‐Me‐4‐(α‐naphthyl)‐1‐Ind)2]ZrCl2/MAO system.
Synthesis, Characterization and Properties of 2‐(Perfluorooctyl)ethylacrylate Grafted Segmented Polyurethaneureas
Authors: Tomita Takehiro , Li Yu‐Jun , Nakaya Tadao 
Published: November 2003

AbstractWe report herein that 2‐(perfluorooctyl)ethylacrylate (PFEA) was successfully grafted onto a segmented polyurethaneurea (SPUU). We found that certain PFEA orientated onto the grafted SPUU film surface could significantly improve hemocompatibility. 1,2‐Propanediamine (PD) as a chain extender was used to synthesize the SPUU, which was based on diphenylmethane diisocyanate (MDI), vinyl group‐containing poly(butadiene) diol (PBD), and hydrogenated poly(isoprene) diol (HPIP). PFEA was copolymerized with the SPUU using α,α′‐azobis(isobutyronitrile) (AIBN) as a radical initiator. Various feed ratios of PFEA grafted polymers were synthesized (SPUU‐F‐0.5, SPUU‐F‐0.75, and SPUU‐F‐1.0) while non‐grafted SPUU was abbreviated as NG‐SPUU. The bulk characteristics of the resulting polymers were investigated by infrared spectroscopy (IR) measurement. Mechanical properties of the typical PFEA grafted SPUU were measured by dynamic viscoelasticity and tensile measurements. We found that PFEA orientated on the surface, as revealed by attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), electron spectroscopy for chemical analysis (ESCA), and water contact angle measurements. The hemocompatibility in vitro was evaluated with rabbit platelet‐rich plasma (PRP) contact tests and viewed by electron probe microanalyzer (EPM) using NG‐SPUU as a reference. We found that fewer platelets adhered to the PFEA grafted surfaces. New polymer SPUU‐F‐0.5 showed the best hemocompatibility in the tested samples. Platelet adhesion to PFEA grafted polymers SPUU‐F‐0.5, SPUU‐F‐0.75, and SPUU‐F‐1.0 was inhibited 91%, 58%, and 50% compared with NG‐SPUU. The relative clotting time of the cast films in contact with cow platelet‐poor plasma (PPP) was 3.26, 2.94, 1.95, 2.39 and 1.00 for SPUU‐F‐0.5, SPUU‐F‐0.75, SPUU‐F‐1.0, NG‐SPUU, and glass, respectively. The new polymers also showed the common characters of fluorinated polymers as revealed by water vapor transmission, dielectric constant, and index of refraction measurements.Structure of the synthesized PFEA Grafted SPUU.magnified imageStructure of the synthesized PFEA Grafted SPUU.