bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic and spectral investigation of the electron and hydrogen adducts of dihydroxy‐ and dimethyl‐substituted pyrimidines: a pulse radiolysis and product analysis study
Authors: Luke T. L. , Mohan H. , Jacob T. A. , Manoj V. M. , Manoj P. , Mittal J. P. , Destaillats H. , Hoffmann M. R. , Aravindakumar C. T.
Published: October 2002

The reactions of hydrated electrons (eaq−) and hydrogen atoms (H·) with 4,6‐dihydroxy‐2‐methylpyrimidine (DHMP), 2,4‐dimethyl‐6‐hydroxypyrimidine (DMHP), 5,6‐dimethyluracil (DMU) and 6‐methyluracil (MU) were studied at different pH values using pulse radiolysis. The second‐order rate constants obtained for the reaction of eaq− with these systems are in the range (5–10) × 109 dm3 mol−1 s−1 at near, neutral pH. At basic pH, the rate constant values were considerably reduced owing to the electrostatic effect between eaq− and pyrimidine anion. The transient absorption spectra of the electron adducts have distinct absorption maxima at around 300–320 nm. The initial spectrum in the case of DHMP at pH 4.5 was found to undergo a first‐order transformation. Based on the spectral characteristics and the yields of methylviologen radical cation (MV·+) resulted from the electron transfer reaction between the electron adducts and MV2+, it is proposed that a protonated (at oxygen) electron adduct of DHMP is initially formed which undergoes a proton‐ and phosphate‐catalysed transformation to form a reducing C(5) protonated C(6)‐yl radical. Such preferential protonation at C(5) is predominant only with dihydroxypyrimidine systems. At pH 9 and 13, formation of a radical monoanion of DHMP (pKa ≥13) is proposed. The possible attack of eaq− is proposed to be at N(1) or N(3) of DMHP. The resulting electron adduct has a pKa value around 6.0. Similar properties for the electron adducts of DMU and MU [electron attack at O(4)] are proposed. The second‐order rate constants for H· with DHMP, DMHP, DMU and MU were in the range (1.7–28) × 108 dm3 mol−1 s−1. The hydrogen adduct spectra were generally identified as their absorption maxima at 310–380 and 460–510 nm. Formation of C(5)‐protonated C(6)‐yl radical, the same radical that formed after the H+‐and phosphate‐catalysed transformation of the electron adduct, is proposed for DHMP. The possibility of the formation of C(5)‐yl and C(6)‐yl H adducts of DMHP, DMU and MU is discussed. High‐performance liquid chromatography coupled with electrospray mass spectrometry (HPLC‐ES‐MS) has been used to qualitatively analyse the products obtained from the reaction of eaq− with DHMP and DMHP and the results revealed that the products are mainly derived from the C(5) protonated C(6)‐yl radicals via its disproportionation and dimerization reaction. A possible reaction mechanism is proposed for the product formation. Copyright © 2002 John Wiley & Sons, Ltd.
The role of specific interactions in crystalline complex formation. Structural and thermochemical analysis of inclusion compounds of cis‐ and trans‐9,10‐bis(4‐bromophenyl)‐9,10‐dihydroxy‐9,10‐dihydroanthracene with dimethyl sulfoxide
Authors: Brehmer Thomas H. , Kirchner Ralf , Seidel Jürgen , Weber Edwin
Published: October 2002

Referring to a crucial problem in crystal engineering and co‐crystallization of host–guest complexes, whether the non‐covalent supramolecular interactions existing in a pre‐crystalline solution state may determine the subsequent crystal structure, the particular inclusion properties of host compounds 1, cis‐ and 2, trans‐9,10‐bis(4‐bromophenyl)‐9,10‐dihydroxy‐9,10‐dihydroanthracene, with dimethyl sulfoxide (DMSO) were studied by using x‐ray structure analysis and calorimetric methods. Both hosts form crystalline inclusion complexes with DMSO showing 2:3 (1·DMSO) and 1:4 (2·DMSO) host:guest composition. The crystal structure of 1·DMSO (2:3) is dominated by a strong bifurcated acceptor‐type H bond interaction involving 1 and one of the DMSO molecules. Titration calorimetric investigations in solution also confirm the formation of a stable 1·DMSO (1:1) complex unit, suggesting that for crystal nuclei of 1·DMSO (2:3) the pre‐formed 1:1 host–guest complex is the relevant building block while the additional molecules of DMSO fill lattice voids. In contrast, compound 2 with a trans configuration of the two hydroxy groups gives much weaker complexation with DMSO in solution, which is in agreement with single H‐bond interaction, also realized in the crystal structure of the respective inclusion complex. Thermal decomposition (TG–DSC) measurements of the crystalline complexes supply supporting data for these findings. Copyright © 2002 John Wiley & Sons, Ltd.
Kinetics and thermodynamics of heat conduction microcalorimetry
Authors: Blandamer Michael J. , Cullis Paul M. , Gleeson Peter T.
Published: October 2002

Heat conduction microcalorimetry offers an important technique in the context of physical organic chemistry for the study of chemical reactions in solution. The thermodynamic basis of the technique is discussed. Model reaction schemes are used in an examination of the dependence on time of the rate of heat production. The impact of rate constants and enthalpies of reaction on the recorded dependence is reviewed for first‐ and second‐order reactions. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of the hydrolysis rate of AOT in AOT–isooctane–water microemulsions using sodium­nitroprusside as chemical probe
Authors: García‐Río L. , Hervés P. , Leis J. R. , Mejuto J. C. , Pérez‐Juste J.
Published: October 2002

The alkaline hydrolysis of sodium nitroprusside, [Fe(CN)5NO]2−, to yield [Fe(CN)5NO2]4− was studied in water in oil (w/o) AOT–isooctane–water microemulsions [AOT = sodium bis(2‐ethylhexyl) sulphosuccinate]. Kinetic data show an initial increase of absorbance at 415 nm, due to the formation of [Fe(CN)5NO2]4−. Following this initial increase, the absorbance started to decrease after a period of time which depends on the particular experimental conditions and returned to the initial value. This anomalous behaviour was interpreted as a result of competitive AOT hydrolysis consuming HO− ions and regenerating [Fe(CN)5NO]2−. The influence of the microemulsion composition on the kinetic results was interpreted in terms of pseudophase formalism, assuming a uniform distribution of HO− and [Fe(CN)5NO]2− ions in the aqueous pseudophase. Analysis of the absorbance–time profiles enables us to obtain the second‐order rate constants for hydrolysis of [Fe(CN)5NO]2− in the water droplet, $\font\smc=cmr10 scaled 800\def\sc#1{\hbox{\smc #1}} = k_{1}^{\rm NP} = 0.108\,\sc{M}^{-1}\hbox{ s}^{-1}$ (half that reported in pure water) and the second‐order rate constant for hydrolysis of the surfactant (AOT), $\font\smc=cmr10 scaled 800\def\sc#1{\hbox{\smc #1}} = k_{2}^{\rm AOT}=4.4\times 10^{-4} \, \sc{M}^{-1} \hbox{ s}^{-1}$, in the microemulsion. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of model linear tetrablock quaterpolymers and pentablock quintopolymers of ethylene oxide
Authors: Ekizoglou Nikos , Hadjichristidis Nikos
Published: October 2002

Multiblock copolymers of ethylene oxide, with four and five different blocks, were synthesized by the sequential anionic polymerization of styrene, isoprene, 2‐vinyl pyridine, t‐butyl methacrylate, and ethylene oxide with benzyl potassium as an initiator. The monomer sequence was based on the relative nucleophilicity of the active centers. Characterization of the multiblock copolymers by size exclusion chromatography (with refractive‐index and UV detectors), membrane osmometry, and NMR spectroscopy confirmed that benzyl potassium is an efficient initiator for the synthesis of well‐defined multiblock multicomponent copolymers of ethylene oxide. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2166–2170, 2002
One‐ and two‐dimensional NMR characterization of N‐vinyl‐2‐pyrrolidone/methyl acrylate copolymers
Authors: Brar A. S. , Kumar Rajeev
Published: October 2002

N‐vinyl‐2‐pyrrolidone/methyl acrylate (V/M) copolymers were prepared by free‐radical bulk polymerization using benzoyl peroxide as an initiator. The copolymer composition of these copolymers was calculated from 1H NMR spectra. The radical reactivity ratios for N‐vinyl‐2‐pyrrolidone (V) and methyl acrylate (M) were rV = 0.09, rM = 0.44. These reactivity ratios for the copolymerization of V and M were determined using the Kelen–Tudos and nonlinear least‐squares error‐in‐variable methods. The 13C{1H} and 1H NMR spectra of these copolymers overlapped and were complex. The complete spectral assignment of the 13C and 1H NMR spectra were done with distortionless enhancement by polarization transfer and two dimensional 13C‐1H heteronuclear single quantum correlation spectroscopic experiments. The two‐dimensional 1H‐1H homonuclear total correlation spectroscopic NMR spectrum showed the various bond interactions, thus inferring the possible structure of the copolymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2225–2236, 2002
Epoxy‐functionalized, low glass‐transition temperature latex. I. Synthesis, characterizations, and polymer interdiffusion
Authors: Tronc Frédéric , Liu Ronghua , Winnik Mitchell A. , Eckersley Sarah T. , Rose Gene D. , Weishuhn J. M. , Meunier D. M.
Published: October 2002

Results are presented on the synthesis and characterization of epoxy‐functionalized poly(butyl acrylate‐co‐methyl methacrylate) latex dispersions. Two pairs of latex dispersions, of low and high molecular weights, were prepared by semicontinuous emulsion polymerization. In each pair, one latex was labeled with phenanthrene, a donor for nonradiative energy‐transfer (ET) experiments, and the other was labeled with anthracene, the acceptor. Films were prepared from 1:1 mixtures of donor‐ and acceptor‐labeled latex, and ET experiments were used to study the rate and extent of polymer diffusion in these films. A complicating feature of these experiments was that, even in the absence of an externally added crosslinking agent, the films began to gel as soon as they were formed. The rate of gel formation increased with increasing temperature but never reached 100% under the conditions of these experiments. The presence of a gel fraction caused the rate of polymer diffusion to slow down. An important parameter affecting the rate of diffusion is the amount of time the films are held at relatively low temperatures (4 and 25 °C) before being annealed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2609–2625, 2002
Characterization of the surface content, hydrolysis ratio, and condensation degree of polyalkoxysiloxane segregated to the surface of a polyurethane crosslinked film by X‐ray photoelectron spectroscopy
Authors: Tomita R. , Urano S. , Kohiki S.
Published: October 2002

We report, using an electron spectrometer equipped with both monochromatized Al Kα and unmonochromatized Mg Kα sources, the quantitative characterization of the surface content, hydrolysis ratio, and condensation degree of polyalkoxysiloxane segregated to the surface of a polyurethane crosslinked film consisting of acryl polyol, polyisocyanate, and polyalkoxysiloxane. Unmonochromatized Mg Kα X‐ray irradiation extremely accelerated the decomposition of alkoxy groups of polyalkoxysiloxane. The surface content and hydrolysis ratio were determined from C 1s, Si 2p, and N 1s spectral intensities measured with monochromatized Al Kα X rays after decomposition by unmonochromatized Mg Kα X‐ray irradiation. The condensation degree was determined by the kinetic energy of the silicon KLL Auger electron after decomposition. We applied the established characterization method for a polyurethane film containing polyalkoxysiloxane. After 20 days, the surface content of polyalkoxysiloxane was greater than 60 wt %, the hydrolysis ratio ranged from 0.8 to 0.95, and the higher hydrolysis ratio resulted in a larger condensation degree. The hydrophilicity of the film surface became higher as the surface content and hydrolysis ratio increased, and the crack density became higher as the condensation degree increased. A method for characterizing the practical properties of coating film surfaces containing polyalkoxysiloxane was established. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2917–2926, 2002
Synthesis of a new amino acid/sulfur dioxide copolymer and its use in aqueous two‐phase polymer systems
Authors: Ali Sk. Asrof , Al‐Muallem Hasan A. , Wazeer Mohamed I. M.
Published: October 2002

The amine salt N,N‐diallyl‐N‐5‐carbomethoxypentylammonium chloride was copolymerized with sulfur dioxide in dimethyl sulfoxide with ammonium persulfate or 2,2′‐azobisisobutyronitrile and afforded a cationic polyelectrolyte (CPE) with a five‐membered cyclic structure on the polymeric backbone. The CPE, upon acidic hydrolysis of the pendent ester groups, gave a corresponding cationic acid salt (CAS) having the equivalent of chloride salt of 6‐N,N‐diallylammoniohexanoic acid as the monomeric unit. The CAS was converted into an anionic polyelectrolyte (APE) and a polybetaine (PB), having the monomeric unit equivalent of sodium 6‐N,N‐diallylaminohexanoate and 6‐N,N‐diallylammoniohexanoate, by treatment with 2 and 1 equiv of base, respectively. The solution properties of APE were investigated by potentiometric and viscometric techniques. The basicity constant of the amine functionality in APE was apparent and as such followed the modified Henderson–Hasselbalch equation; the protonation of the APE became more and more difficult as the degree of protonation of the whole macromolecule increased. The compositions and phase diagrams of the aqueous two‐phase systems of APE and poly(ethylene glycol) were studied. The PB was found to be insoluble in water, and this paves the way for the potential use of APE in aqueous two‐phase polymer systems for protein purification and its removal and recycling by conversion into PB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2464–2477, 2002
Pd(0)‐catalyzed polyaddition of bifunctional vinyloxiranes with 1,3‐dicarbonyl compounds: The synthesis of polymers containing hydroxy and carbonyl groups
Authors: Koizumi Toshio , Sakamoto Jun , Gondo Yasuhiko , Endo Takeshi
Published: October 2002

The palladium(0)‐catalyzed polyaddition of bifunctional vinyloxiranes [1,4‐bis(2‐vinylepoxyethyl)benzene (1a) and 1,4‐bis(1‐methyl‐2‐vinylepoxyethyl)benzene (1b)] with 1,3‐dicarbonyl compounds [methyl acetoacetate (4), dimethyl malonate (6), and Meldrum's acid (8)] was investigated under various conditions. The polyaddition of 1 with 4 was carried out in tetrahydrofuran with phosphine ligands such as PPh3 and 1,2‐bis(diphenylphosphino)ethane (dppe). Polymers having hydroxy, ketone, and ester groups in the side groups (5) were obtained in good yields despite the kinds of ligands employed. The number‐average molecular weight value of 5b was higher than that of 5a. The polyaddition of 1b and 6 was affected by the kinds of ligands employed. The corresponding polymer 7b was not obtained when PPh3 and 1,2‐bis(diphenylphosphino)ferrocene were used. The polyaddition was carried out with dppe as the ligand and gave polymer 7b in a good yield. The molecular weight of the polymer obtained from 1b and 8 was much higher than those of polymers 5b and 7b. The polyaddition with Pd2(dba)3 · CHCl3/dppe as a catalyst (where dba is dibenzylideneacetone) produced polymer 9b in a 92% yield (number‐average molecular weight = 45,600). The stereochemistries of all the obtained polymers were confirmed as an E configuration by the coupling constant of the vinyl proton. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2487–2494, 2002
Influence of diluent composition on the porous structure of methacrylate copolymers
Authors: Gawdzik Barbara , Maciejewska Małgorzata
Published: October 2002

The porous structure of copolymers obtained by suspension polymerization has been investigated. Three different copolymers were synthesized—styrene‐divinylbenzene, ethylene glycol dimethacrylate‐divinylbenzene, and 1,4‐phenylene dimethacrylate‐divinylbenzene. All the copolymers were porous. As a pore‐forming diluent, the mixture of toluene (good solvent) and n‐dodecane (nonsolvent) was used. The influence of the composition of two‐component diluent on the porous structure of the copolymers has been examined. Surface areas, pore volumes, pore size distributions, skeletal and apparent densities, and swellability coefficients were determined for the copolymers obtained in the presence of 0, 15, 50, 85, and 100% (v/v) toluene in the mixture with n‐dodecane. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3079–3085, 2002
X‐ray powder diffraction of polymer/layered silicate nanocomposites: Model and practice
Authors: Vaia Richard A. , Liu Weidong
Published: October 2002

X‐ray powder diffraction in reflection (Bragg–Brentano parafocusing geometry) is extensively used to characterize the structure of polymer/layered silicate nanocomposites (PLSNs). The large basal spacings (d001 > 2.0 nm) necessitates the collection of data at scattering angles (2θ) of less than 10°. The calculation of an ideal scattering profile for PLSNs provides an avenue to ascertain the influence of experimental parameters and the arrangement, organization, concentration, and composition of constituents on the experimentally observed pattern. This enables better experimental technique, more complete utilization of the scattering data, insight into inconsistencies between scattering and microscopy, and minimization of incorrect interpretation or overinterpretation of data. Because of the strong θ dependence of theoretical and experimental factors at low values of 2θ, careful sample preparation and data evaluation are necessary and should be complemented by microscopic observations, especially for PLSNs with low volume fractions of organically‐modified layered silicates (OLS) that are suspected of having exfoliated morphologies. X‐ray powder diffraction in reflection alone is insufficient to completely characterize and ascribe PLSN morphology. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1590–1600, 2002
Synthesis and structural characterizations of [chromophore]+‐saponite/polyurethane nanocomposites
Authors: Wang Wu‐Jing , Chin Wei‐Kuo , Wang Wan‐Ju
Published: October 2002

In this study, three chromophores—p‐nitroaniline, 4‐(4‐nitrophenylazo)aniline, and 4‐[(E)‐2‐{4‐[(E)‐2‐(4‐nitrophenyl)‐1‐diazenyl]phenyl}‐1‐diazenyl]aniline—were intercalated into layered aluminosilicate saponite and then dispersed into the polyurethanes matrix. The intercalated chromophore/saponite complexes were examined by inductively coupled plasma emission and element analysis technologies. The molecular orbital package computation simulation and X‐ray diffraction (XRD) analysis showed that possible configurations of chromophore ions on the gallery surfaces of saponite suggest that the chromophore molecules lie parallel to the basal planes of silicate as an inclined paraffin structure or as pseudo‐multilayers. The XRD and transmission electron microscopy analysis indicated that the delamination of organoclay in the polyurethanes matrix exhibited nanolayers, exfoliated structure, or both. In particular, even at high doping levels up to 15 wt % of organoclay, the [chromophore]+‐saponite/polyurethanes film did not display a macroscopic aggregation of layered silicates and showed high transparency. The thermal stability of chromophore was significantly enhanced as intercalated into the layered aluminosilicate saponite, and the glass‐transition temperature of [chromophore]+‐saponite/polyurethanes nanocomposites proportionally increased with increased clay content. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1690–1703, 2002
Study of the interfacial structure in epoxy bilayer films using neutron reflection
Authors: Yim H. , Kent M. S. , Jeon H. S. , Smith G.
Published: October 2002

The interfacial structure in thin epoxy bilayer films was investigated with neutron reflection. For each experiment, a mixture of crosslinker and deuterated resin was spun onto a chemically similar, fully cured, protonated epoxy film. The reflectivity measurements were performed before and after curing the top epoxy film. We focused on the extent of penetration of the components of the top layer into the network of the bottom layer. The effect of the cure temperature of each layer was examined. In addition, the effect of the initial molecular weight of the oligomers in the top layer was probed by the partial curing of the mixture before spinning. As deposited, the components of the top layer penetrated the bottom layer to an extent that was largely independent of the aforementioned factors. The principal observation was that an additional penetration occurred with curing. This additional penetration was dependent upon both the molecular weight of the top layer and the cure temperature of the top layer relative to the glass‐transition temperature of the bottom layer. A decrease in the thickness of the top layer with curing was also observed, which likely indicates some evaporation of oligomers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1709–1718, 2002
Characterization of volume strain of poly(vinylidene fluoride) under creep test
Authors: Elkoun S. , G'Sell C. , Cangemi L. , Meimon Y.
Published: October 2002

Poly(vinylidene fluoride) (PVDF) was subjected to a creep test performed at constant true stress. The use of an original method to control and adjust, in real time, the stress allowed the assessment of volume changes occurring during the test. The adaptation of Bucknall's model enabled us to excerpt the component related to microstructural modifications from the whole volume strain. Mechanisms inducing volume strain are temperature dependent. Above −40 °C and below 80 °C, that is, in between both glass transitions of PVDF, a linear increase of volume strain was observed as a result of polymer damage via the crazing phenomenon. In addition, this region is characterized by the presence of two distinct domains that could be attributed to either nucleation and propagation of voids or to an increase of the number of potential sites for nucleation resulting from microstructural modifications taking place during the test. On the contrary, above the secondary glass transition, a regular decrease of volume strain was observed. It was assigned to a material densification as a result of molecular orientation of the amorphous chain segments. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1754–1759, 2002
Ionic interaction behavior and facilitated olefin transport in poly(n‐vinyl pyrrolidone):Silver triflate electrolytes; Effect of molecular weight
Authors: Kim Jong Hak , Min Byoung Ryul , Kim Chang Kon , Won Jongok , Kang Yong Soo
Published: October 2002

Interactions of cation/anion and cation/polymer in poly(N‐vinyl pyrrolidone) (PVP):silver triflate (AgCF3SO3) electrolytes with different weight‐average molecular weights (Mw's) of 1 × 106 (1 M), 3.6 × 105 (360 K), 4 × 104 (40 K), and 1 × 104 (10 K) have been studied with IR and Raman spectroscopies. According to the change of the CO peak, coordination of silver ions by CO in a low Mw (10 or 40 K) PVP matrix tend to be always thermodynamically favorable than high Mw (1 M or 360 K) PVP, demonstrating that the polymer matrix of low Mw dissolves silver salts more effectively. In addition, silver cations interact with both larger SO and smaller CF3 to form ion pairs, and the former interaction is stronger than the latter in a monomer or low Mw polymer matrix (40 K, 10 K), as demonstrated by theoretical ab initio calculation or experimental spectroscopy, respectively. However, CF3 interacts more favorably with silver cation than SO in high Mw (1 M and 360 K) PVP, which is ascribed to the steric effect of the bulky SO anion by highly entangled polymer chains. Despite the superior dissolving property of the low Mw polymer matrix, the membranes consisting of low Mw PVP and AgCF3SO3 exhibited poor separation performance for propylene/propane mixtures in comparison with those of high Mw, presumably because of the poor mechanical property for membrane formation in low Mw PVP. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1813–1820, 2002
Synthesis and characterization of difluor‐aniline polymers
Authors: Rubio L. L. , Castillo‐Ortega M. M. , Rejon L. , Olayo R. , Cruz G. J.
Published: October 2002

Undoped and chlorine doped difluoraniline polymers (PDFA) were synthesized and characterized to study the electric behavior of polyanilines with three different fluorine disubstitutions in the benzene rings that could produce polarizable molecules. The structures of the resulting polymers were studied by infrared spectroscopy focusing in the oxidation degree in the polymers. A discussion of the molecular weight of PDFAs as measured by light scattering in different solvents is presented, since the polymers form aggregates depending on the solvent used, the position of the fluorine substitutions, the doping level and the temperature. The aggregates in polarizable polymer solutions can produce wrong estimations in the molecular weight if the influence of temperature is not considered. The PDFAs thermal and electroconductivity analysis also showed dependence on the position of the fluorine substitutions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2130–2136, 2002
Novel characterization of the crystalline segment distribution and its effect on the crystallization of branched polyethylene by differential scanning calorimetry
Authors: Teng Hongxiang , Shi Yi , Jin Xigao
Published: October 2002

Based on a thermal segregation treatment, a novel semiquantitative method for the characterization of the crystalline segment distribution in branched polyethylene copolymers was established by the results of differential scanning calorimetry being treated with the Gibbs–Thomson equation. The method was used to describe the segment distribution of Ziegler–Natta‐catalyzed linear low‐density polyethylene (Z–N LLDPE), metallocene‐catalyzed linear low‐density polyethylene (m‐LLDPE), and a commercial linear low‐density polyethylene with a wide molecular weight distribution. The isothermal crystallization kinetics of Z–N LLDPE and m‐LLDPE were studied to assess the effect of different segment distributions. According to their molecular characteristics, the crystallization behaviors were analyzed. They indicated that the different segment distributions of the two polymers resulted in different crystallization processes, including the nucleation and growth of crystals under various crystallization conditions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2107–2118, 2002
Nature and distribution of frozen saline sediments on the Russian Arctic coast
Authors: Brouchkov Anatoli
Published: October 2002

Frozen saline sediments are widely distributed along the Russian Arctic coast and in other regions. They have unique properties and are characterized by low bearing capacity. The origin of the salinity is related to seashore processes. The salts within porous solutions are partially taken out upon freezing, and redistributed. Salt moves, together with water, to the freezing front of clay deposits, and, by contrast, away from the freezing front in sand. Salinization is determined by both the conditions at formation, and subsequent processes at cryogenic temperatures. An increase in salinization with depth is observed. This is most likely caused by moving of salts from the upper permafrost layers as the result of the migration of pore water. Salinization in general increases with an increase in ice content. Changes in salinization cause changes of cryogenic structure. An important feature of the saline soils of the Russian Arctic coast is their heterogeneity. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of salmeterol on arterial oxyhemoglobin saturations in patients with cystic fibrosis
Authors: Salvatore Donatello , D'Andria Michele
Published: October 2002

Sleep‐related oxygen desaturation has been described in patients with cystic fibrosis (CF). Thus we studied the effects of inhaled Salmeterol xinafoate, a long‐acting beta‐2 agonist, on transcutaneous oxyhemoglobin saturation in sleeping, stable CF patients. Patients with stable CF (n = 23) were divided into responders and nonresponders to beta‐2 agonists, based on an albuterol challenge during daytime testing, and then they received salmeterol before sleep, in a double‐blind crossover design. Overnight oxyhemoglobin saturation measurements and spirometry on awakening were performed.

Salmeterol administration before sleep resulted in statistically significant increases in mean arterial oxyhemoglobin saturation and in FEV1 and FEF25–75 on awakening compared to placebo values, but only in patients responding to daytime albuterol inhalation by showing improvement in lung function.

We conclude that salmeterol inhalation at bedtime could prevent or reduce nocturnal hypoxemia in daytime albuterol‐responsive CF patients, thus improving the long‐term clinical outcome of CF lung disease. Pediatr Pulmonol. 2002; 34:11–15. © 2002 Wiley‐Liss, Inc.
Pulmonary hypoplasia with an unusual prenatal history
Authors: Takahashi Ritsuko , Kakizawa Hideyuki , Itow Takeshi , Yamada Masaaki , Nakae Shingi , Shintaku Yoshiyuki , Nagata Michio , Nakayama Masahiro
Published: October 2002

We describe a monochorionic, diamniotic twin with renal agenesis who received amniotic fluid from his normal co‐twin by spontaneous rupture of the amniotic septum between them. By 16 weeks of gestation the presence of severe oligohydramnios in one twin had resulted in renal agenesis, but not in the other twin, who did not have oligohydramnios. By 20 weeks of gestation, the two amniotic fluid volumes had become the same in both twins. At 33 weeks, the twins were delivered by cesarean section. Despite intensive respiratory care, the twin with renal agenesis died from severe pneumomediastinum on day 3. At autopsy, pulmonary hypoplasia was demonstrated in that twin. This experiment of nature demonstrates that oligohydramnios during the early canalicular stage of pulmonary development (gestational age, 16–20 weeks) may be pathogenically important in pulmonary hypoplasia. Pediatr Pulmonol. 2002; 34:218–221. © 2002 Wiley‐Liss, Inc.
Expression of urocortin mRNA and peptide in the human prostate and in prostatic adenocarcinoma
Authors: Arcuri Felice , Cintorino Marcella , Florio Pasquale , Floccari Federica , Pergola Loreta , Romagnoli Roberta , Petraglia Felice , Tosi Piero , Teresa del Vecchio Maria
Published: October 2002

BACKGROUND

Urocortin (UCN) is a recently described neuropeptide member of the CRF family, responsible for the secretion of the proopiomelanocortin‐derived peptides from the pituitary gland. Although previous results have demonstrated the synthesis of several neuroendocrine factors in the prostate, no studies have been carried out on the expression of UCN in the human gland.

METHODS

UCN expression was evaluated in benign prostatic hyperplasia and prostatic tumor tissues by RT‐PCR and immunohistochemistry.

RESULTS

UCN mRNA and peptide were demonstrated in all specimens tested. In nonneoplastic tissues, UCN was localized in the secretory luminal epithelial and basal layer cells, in the smooth muscle component of the stroma, and in lymphoid infiltrates. An intense immunostaining was evident in prostate adenocarcinoma cells.

CONCLUSIONS

The results of the present study demonstrate for the first time UCN expression in the human prostate and in prostate cancer, and suggest a potential involvement of UCN in prostate physiopathology. Prostate 52:167–172, 2002. © 2002 Wiley‐Liss, Inc.
Direct effect of zinc on mitochondrial apoptogenesis in prostate cells
Authors: Feng Pei , Li Tie‐Luo , Guan Zhi‐Xin , Franklin Renty B. , Costello Leslie C.
Published: October 2002

BACKGROUND

Prostate epithelial cells uniquely accumulate significantly higher levels of zinc than other mammalian cells. We previously showed that the accumulation of high intracellular zinc levels in specific prostate cells results in the induction of apoptosis and the inhibition of cell growth. The apoptotic effect is due to zinc induction of mitochondrial apoptogenesis. We now report additional studies that corroborate this effect of zinc and provide insight into the mechanism of this unique effect.

METHODS

The effect of exposure to physiological levels of zinc on apoptosis was determined for three human prostate cell lines (PC‐3, BPH, and HPR‐1). Zinc‐induced apoptosis was identified by DNA fragmentation. The direct effect of zinc on isolated mitochondrial preparations from each cell line was determined. The mitochondrial release of cytochrome c was determined by Western blot.

RESULTS

Exposure to zinc induced apoptosis in PC‐3 and BPH cells but not in HPR‐1 cells. The zinc accumulation in PC‐3 (4.3 ± 0.3) and BPH (2.8 ± 0.4) was higher than that in HPR‐1 cells (1.8 ± 0.1). The apoptotic effect of zinc on PC‐3 cells could be observed as early as 4–6 hr of zinc treatment, and this effect was not reversible. The exposure of isolated mitochondria from PC‐3 and BPH cells to zinc resulted in the release of cytochrome c; but zinc had no effect on mitochondria from HPR‐1 cells.

CONCLUSIONS

Exposure to zinc induces apoptosis in PC‐3 and BPH cells, which accumulate high intracellular levels of zinc, but not in HPR‐1 cells, which do not accumulate high levels of zinc. Once initiated, the induction of apoptosis is not reversed by the removal of zinc, i.e., it is an irreversible process. The apoptogenic effect is due to a direct effect of zinc on mitochondria that results in the release of cytochrome c. The cell specificity of zinc induction of apoptogenesis is dependent on the ability of the cells to accumulate high levels of intracellular zinc and on the ability of the mitochondria to respond to the direct effect of zinc. Prostate 52: 311–318, 2002. © 2002 Wiley‐Liss, Inc.
Loss of heterozygosity at 7q31.1 and 12p13‐12 in advanced prostate cancer
Authors: Kawana Yoko , Ichikawa Tomohiko , Suzuki Hiroyoshi , Ueda Takeshi , Komiya Akira , Ichikawa Yayoi , Furuya Yuzo , Akakura Koichiro , Igarashi Tatsuo , Ito Haruo
Published: October 2002

BACKGROUND

Allelic losses on chromosome arms 2q, 3p, 5q, 6q, 7q, 8p, 9p, 10p, 10q, 11p, 11q, 12p, 13q, 16q, 17p, 17q, 18q, and 21q are reportedly associated with progression and/or initiation of prostate cancer. In the present study, we performed a polymerase chain reaction (PCR) analysis of polymorphic microsatellite loci on the human chromosomes 7 and 12p13‐12 in prostate cancer tissue to investigate the extent of involvement of these regions, which may contain putative tumor suppressor genes.

METHODS

Tissue samples were obtained at autopsy from 17 men who died of hormone‐refractory prostate cancer at Chiba University, Japan, and affiliated hospitals between June of 1992 and June of 1995. DNA from normal tumor or metastatic tissue was used as the template for PCR amplification of a set of 16 polymorphic microsatellite loci on human chromosome 7 and 6 loci on the human chromosome region 12p13‐12.

RESULTS

The frequencies of cases with loss of heterozygosity (LOH) at 7q31.1 were 8% in primary tumor tissue and 11% in metastatic tissue. The frequencies of cases with LOH at 12p13‐12 were 12% in primary tumor tissue and 25% in metastatic tumor tissue.

CONCLUSIONS

In the present study, the frequencies of LOH at 7q31.1 were lower than in Western patients, suggesting that LOH in this region is not related to progression of prostate cancer in Japanese patients. The frequency of LOH at 12p13‐12 was similar to that reported in Western countries, indicating that 12p13‐12 may contain a tumor suppressor gene of prostate cancer. Prostate 53: 60–64, 2002. © 2002 Wiley‐Liss, Inc.
Linkage between polymorphisms in the prostate specific antigen ARE1 gene region, prostate cancer risk, and circulating tumor cells
Authors: Medeiros Rui , Morais Antonio , Vasconcelos André , Costa Sandra , Pinto Daniela , Oliveira Jorge , Carvalho Rodrigo , Lopes Carlos
Published: October 2002

BACKGROUND

The prostate specific antigen (PSA) gene has a polymorphic androgen response element (ARE) sequence with two alleles, A and G. PSA A‐allele carriers have higher serum PSA levels in healthy men (HM).

METHODS

We analysed DNA samples from 278 (556 alleles) unrelated individuals, 127 HM and 151 prostate cancer (PC) patients, for PSA ARE1 genotypes.

RESULTS

The analysis of the frequencies from the 556 alleles indicates a significant overrepresentation of A‐allele in the PC group under the age of 67 compared with the HM group (63.3% vs. 48.8%; P = 0.009). We found that men carrying two A‐alleles have increased risk for PC onset under the age of 67 (odds ratio [OR] = 2.92; 95% confidence interval [CI], 1.10–7.86; P = 0.013). Multivariate logistic regression analysis confirmed this association (OR = 1.82; 95% CI, 1.03–3.22; P = 0.037). Furthermore, the homozygosity for the A‐allele was associated with higher serum PSA levels (P = 0.027) and with the presence of circulating tumor cells in the blood of PC patients (P = 0.018).

CONCLUSION

Our results indicate that polymorphism in the PSA gene promoter may be an important biomarker for prostate cancer risk, especially for an earlier onset of PC. Prostate 53: 88–94, 2002. © 2002 Wiley‐Liss, Inc.
Entropic benefit of a cross‐link in protein association
Authors: Zaman Muhammad H. , Berry R. Stephen , Sosnick Tobin R.
Published: October 2002

We introduce a method to estimate the loss of configurational entropy upon insertion of a cross‐link to a dimeric system. First, a clear distinction is established between the loss of entropy upon tethering and binding, two quantities that are often considered to be equivalent. By comparing the probability distribution of the center‐to‐center distances for untethered and cross‐linked versions, we are able to calculate the loss of translational entropy upon cross‐linking. The distribution function for the untethered helices is calculated from the probability that a given helix is closer to its partner than to all other helices, the “Nearest Neighbor” method. This method requires no assumptions about the nature of the solvent, and hence resolves difficulties normally associated with calculations for systems in liquids. Analysis of the restriction of angular freedom upon tethering indicates that the loss of rotational entropy is negligible. The method is applied in the context of the folding of a ten turn helical coiled coil with the tether modeled as a Gaussian chain or a flexible amino acid chain. After correcting for loop closure entropy in the docked state, we estimate the introduction of a six‐residue tether in the coiled coil results in an effective concentration of the chain to be about 4 or 100 mM, depending upon whether the helices are denatured or pre‐folded prior to their association. Thus, tethering results in significant stabilization for systems with millimolar or stronger dissociation constants. Proteins 2002;48:341–351. © 2002 Wiley‐Liss, Inc.
Prediction of an HMG‐box fold in the C‐terminal domain of histone H1: Insights into its role in DNA condensation
Authors: Bharath M.M. Srinivas , Chandra Nagasuma R. , Rao M.R.S.
Published: October 2002

In eukaryotes, histone H1 promotes the organization of polynucleosome filaments into chromatin fibers, thus contributing to the formation of an important structural framework responsible for various DNA transaction processes. The H1 protein consists of a short N‐terminal “nose,” a central globular domain, and a highly basic C‐terminal domain. Structure prediction of the C‐terminal domain using fold recognition methods reveals the presence of an HMG‐box‐like fold. We recently showed by extensive site‐directed and deletion mutagenesis studies that a 34 amino acid segment encompassing the three S/TPKK motifs, within the C‐terminal domain, is responsible for DNA condensing properties of H1. The position of these motifs in the predicted structure corresponds exactly to the DNA‐binding segments of HMG‐box‐containing proteins such as Lef‐1 and SRY. Previous analyses have suggested that histone H1 is likely to bend DNA bound to the C‐terminal domain, directing the path of linker DNA in chromatin. Prediction of the structure of this domain provides a framework for understanding the higher order of chromatin organization. Proteins 2002;49:71–81. © 2002 Wiley‐Liss, Inc.
Meta‐analysis of QTc interval – pooling data from heterogeneous trials
Authors: Webber Dawn M. , Montague Timothy H. , Bird Nick P.
Published: October 2002

A diverse range of non‐cardiovascular drugs are associated with QT interval prolongation, which may be associated with a potentially fatal ventricular arrhythmia known as torsade de pointes. QT interval has been assessed for two recent submissions at GlaxoSmithKline. Meta‐analyses of ECG data from several clinical pharmacology studies were conducted for the two submissions. A general fixed effects meta‐analysis approach using summaries of the individual studies was used to calculate a pooled estimate and 90% confidence interval for the difference between each active dose and placebo following both single and repeat dosing separately. The meta‐analysis approach described provided a pragmatic solution to pooling complex and varied studies, and is a good way of addressing regulatory questions on QTc prolongation. Copyright © 2002 John Wiley & Sons, Ltd.
Top tip: ways of dealing with analytical constraints in pharmaceutical technology
Authors: Jones Phil
Published: October 2002

In this paper several methods are presented for managing analytical constraints in support of formulation optimization and drug delivery studies. These methods rely on the sequential analytical analysis of pharmaceutical technology studies. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibitory effects of echinoisoflavanone and sophoraisoflavanone D in Sophora chrysophylla SEEM on copper ion‐induced protein oxidative modification of mouse brain homogenate in vitro
Authors: Toda Shizuo , Shirataki Yoshiaki
Published: October 2002

We present the results of an in vitro investigation of the inhibitory effects of echinoisoflavanone and sophoraisoflavanone D isolated from Sophora chrysophylla SEEM on copper‐induced protein oxidative modification of mouse brain homogenate in vitro. They inhibited copper‐induced protein oxidative modification. The order of inhibitory effects of these isoflavanones and mannitol as a hydroxyl radical scavenger was sophoraisoflavanone D > mannitol > echinoisoflavanone.

The results suggest that these natural products may be of use in cases where oxidative stress is present. Copyright © 2002 John Wiley & Sons, Ltd.
Does placebo continue to please or merely placate?
Authors: Charnley Nickols Pamela
Published: October 2002

‘The current paradigm is that a placebo‐controlled design is the gold standard for proving efficacy’ (Drug Inform J, 2001; 35:1147). Although International Conference on Harmonisation (ICH) Guideline E10 (Proceedings of the International Conference on Harmonisation, European Agency for the Evaluation of Medical Products; London, UK, July 27, 2000) reinforces this view, E10 appears to underestimate the problems associated with such studies. Disadvantages are mentioned in E10 and include ethical concerns, patient and investigator concerns and problems of generalisability but the guideline underplays these concerns, particularly the ethical aspects. The Declaration of Helsinki (World Medical Association: Edinburgh, Scotland, October 2000) reflects changing public and professional opinion about the acceptability of placebo controls and the Edinburgh 2000 version is perceived as a firmer statement of this than previously. The role of placebo is viewed as increasingly less acceptable in the light of ongoing development of more numerous and effective treatments. Published in 2002 by John Wiley & Sons, Ltd.
Society of Quality Assurance ‐ council on professional registration
Authors: Klahm Lynn
Published: October 2002

Early in 1993, the Society of Quality Assurance (SQA) Board of Directors established the Professional Certification Com‐mittee (PCC) to address the utility, feasibility and acceptability of professional certification for the quality assurance professional. This article presents an overview of the development of the Council on Professional Registration, data on the examinations 1997 to 2001, and a listing of those individuals who participated in the development of the program and the Council. Copyright © 2002 John Wiley & Sons, Ltd.
Some notes on the construction and evaluation of supersaturated designs
Authors: Holcomb Don R. , Carlyle W. Matthew
Published: October 2002

Supersaturated designs offer a potentially useful way to investigate many factors with few experiments. A super‐saturated design evaluates $m$ factors with $n$ experiments, where $m \geq n-1$. In some supersaturated designs the number of factors being investigated may exceed the number of experiments by a factor of three or more. The problem of developing a supersaturated design is described in computational complexity terms and methods of construction are discussed. Using standard combinatorial formulation may permit researchers to use additional methods to develop additional designs. Designs are generated with a modified method and compared with published designs using existing criteria and a new criterion. Copyright © 2002 John Wiley & Sons, Ltd.
Charge transfer mechanism in N4+ + He and B3+ + He/H2 ion–atom/molecule collisions
Authors: Tergiman Y. S. , Fraija F. , Bacchus‐Montabonel M. C.
Published: October 2002

Ab initio potential energy curves and coupling matrix elements of the molecular states involved in the collision of the N4+(2s)2S and B3+(1s2)1S multicharged ions on the helium atom or molecular hydrogen have been determined by means of configuration interaction methods. The total and partial electron capture cross‐sections have been evaluated in the frame of a semiclassic approach in the 1‐ to 100‐keV laboratory energy range and compared to experimental data. A comparative study of both targets is performed in the case of the B3+ ion. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Formulation of Strutinsky's method for atomic systems in the extended Kohn–Sham scheme
Authors: Kuleff A. I. , Delchev Y. I. , Yotov P. Tz. , Mineva Tz. , Maruani J.
Published: October 2002

Strutinsky's standard averaging method is formulated in the framework of the extended Kohn–Sham scheme and a two‐step procedure permitting the application of the method is proposed. A Taylor‐series expansion of the ground‐state energy‐function of the occupation numbers is derived, which involves the averaged energy as the leading term and shell corrections as smaller terms. Numerical applications for atoms and ions from Be through Ar are presented and discussed. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Quantization on curved surfaces
Authors: Mladenov Ivaïlo M.
Published: October 2002

After a short review of the existing methods for quantization of curved manifolds, the free particle motions or the so‐called geodesic flows on axisymmetrical prolate and oblate ellipsoids are quantized using the isomorphism established by Neumann of these systems and the harmonic oscillator restricted to the unit sphere. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Mechanism of the oxidation reaction of Cu with N2O via nonadiabatic electron transfer
Authors: Kryachko Eugene S. , Tishchenko Oksana , Nguyen Minh Tho
Published: October 2002

We treat the present work as an attempt to elucidate the mechanism of the oxidation reaction of the Cu atom by nitrous oxide based on our recent work (Kryachko, E. S.; Vinckier, C.; Nguyen, M. T. J Chem Phys 2001, 114, 7911) on the electron attachment to this molecule. We suggest that the title reaction in its Arrhenius regime occurs via the nonadiabatic electron transfer from Cu to the oxygen atom at the crossing of the potential energy surfaces Cu(4s 2S1/2) + N2O(X 1Σ+) and Cu+ + N2O−, where the latter is linked to the complex N2O− originated from the higher‐energy T‐shape N2O molecule and discovered in the aforementioned work. The calculations performed in the present work using a variety of quantum chemical methods support the proposed model. We also show the existence of other reaction pathways of the title reaction that, we believe, contribute to its non‐Arrhenius behavior observed experimentally at T > 1190 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002