bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on K2S2O8/ascorbic acid initiated synthesis of Ipomoea dasysperma seed gum‐g‐poly(acrylonitrile): A potential industrial gum
Authors: Singh Vandana , Tiwari Ashutosh , Sanghi Rashmi 
Published: August 2005

AbstractSeed gum from Ipomoea dasysperma was grafted with polyacrylonitrile using potassium persulfate/ascorbic acid redox initiator in the presence of molecular oxygen, where the maximum percentage grafting and percentage efficiency observed were 360 and 97.2%, respectively. Optimal grafting conditions were established for the gum and a representative polyacrylonitrile grafted gum was characterized using FTIR, NMR, X‐ray diffraction, and TGA studies. Grafted gums with %G up to 185% showed water solubility; thereafter, the solubility in water was observed to decrease with the increase in %G. After the saponification of the nitrile groups to amide and carboxylic acid groups, the water retention of the grafted gum increased significantly and this increase was dependent on the extent of grafting. Various properties like viscosity, gel/film forming ability, shelf life of the grafted gum solutions (with samples where %G were not >185%) along with the water, and saline retention capacity were studied and compared with that of the parent gum to evaluate it for industrial applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1652–1662, 2005
Synthesis and swelling properties of pH‐sensitive hydrogels based on chitosan and poly(methacrylic acid) semi‐interpenetrating polymer network
Authors: Chen Shilan , Liu Mingzhu , Jin Shuping , Chen Yong 
Published: August 2005

AbstractA novel semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of chitosan and poly(methacrylic acid) was synthesized using formaldehyde as a crosslinker. The amount of crosslinker was searched and optimized. The structure of the hydogel was investigated by Fourier transform infrared (FTIR) spectroscopy. The spectrum shows that a structure of polyelectrolyte complex exists in the hydrogel. The effects of pH, ionic strength, and inorganic salt on the swelling behaviors of the hydrogel were studied. The results indicate the hydrogel has excellent pH sensitivity in the range of pH 1.40 to 4.50, pH reversible response between pH 1.80 and 6.80, and ionic strength reversible response between ionic strength 0.2 and 2.0M. The results also show that the hydrogel has a bit higher swelling capacity in a mix solution of calcium chloride (CaCl2) and hydrochloric acid (HCl) solution than in a mix solution of sodium chloride (NaCl) and HCl. These results were further confirmed through morphological change measured by scanning electron microscope (SEM). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1720–1726, 2005
Interfacial modification of high density polyethylene/glass fiber reinforced and non reinforced polyamide 66 blends
Authors: Baouz T. , Fellahi S. 
Published: August 2005

AbstractHigh density polyethylene (HDPE) and polyamide (PA66) are well known to be incompatible. An ionomer (Surlyn) was added as a compatibilizer to HDPE and glass fiber reinforced (HDPE/GFRPA66) and non‐reinforced (HDPE/PA66) blends. Two compositions were considered: 25/75 wt % and 75/25 wt %, with an emphasis on the former formulation. The influence of the compatibilizer on the rheology, thermal properties, and the morphology, as well as mechanical properties of the blends, was investigated using melt flow index measurements, DSC, scanning electron microscopy (SEM), and impact strength. The ionomer was found to be more effective as a compatibilizer with HDPE as a minor phase compared to the case when HDPE becomes the major phase. The results indicated that the interfacial properties of the blends were improved, with a maximum appearing at a critical concentration of the ionomer (7.5 vol %). At this level of compatibilization, SEM analysis revealed better interfacial adhesion and a finer dispersion. MFI results revealed a probable reaction between the amine groups of PA66 and the acid functions of the ionomer. The mechanical properties support the above results and showed that the addition of 25 wt % HDPE did not affect the properties of PA66 much and the presence of glass fiber did not hinder the effect of the compatibilizer. Only 20% decrease in notched Izod impact strength of the blends is observed at 7.5 vol % ionomer content, suggesting that the addition of 25 wt % of HDPE to PA66 is not detrimental at this level of compatibilization. The emulsification curve was established and revealed that, in terms of impact properties, the finer the particle size, the higher the impact strength corresponding to 7.5 vol % ionomer content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1748–1760, 2005
New optically active poly(amide–imide–urethane) thermoplastic elastomers derived from poly(ethylene glycol diols), 4,4′‐methylene‐bis(4‐phenylisocyanate), and a diacid based on an amino acid by a two‐step method under microwave irradiation
Authors: Mallakpour Shadpour , Rafiemanzelat Fatemeh 
Published: August 2005

AbstractA new class of optically active poly(amide–imide–urethane)s (PAIUs) was synthesized via a two‐step diisocyanate route under microwave irradiation. In these reactions, 4,4′‐methylene‐bis(4‐phenylisocyanate) was reacted with bis(p‐amido benzoic acid)‐N‐trimellitylimido‐L‐leucine and poly(ethylene glycol diol)s (PEGs), such as PEG‐400, PEG‐600, PEG‐1000, and PEG‐2000, to furnish a series of new PAIUs. The effects of different reaction conditions, such as the method of preparation (polyol or acid chain extension), the prepolymerization step (NCO‐terminated oligoamide or NCO‐terminated polyether polyol), the irradiation time and power, the reaction solvent, the soft‐segment length, and the presence or absence of reaction catalysts (e.g., triethylamine, pyridine, and dibutyltin dilaurate), on the properties of the copolymers, including the solubility, viscosity, and thermal behavior, were investigated. The resulting multiblock copolymers had inherent viscosities of 0.15–0.53 dL/g. These multiblock copolymers were optically active, thermally stable, and soluble in amide‐type solvents. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1781–1792, 2005
Comparison of systemic exposure to nemifitide following two methods of subcutaneous administration to healthy volunteers
Authors: Nicolau G. , Feighner J.P. , Stout R. , Hlavka J. , Gutierrez M. , Ciric S. , Freed J. 
Published: August 2005

AbstractThe purpose of this study was to evaluate the safety and pharmacokinetics of nemifitide, a synthetic antidepressant pentapeptide, following its subcutaneous (s.c.) administration by standard needle injection or by a needle‐free (Bioject™) injection and to compare these two routes of administration for systemic exposure. This small‐scale, randomized, single‐dose, parallel design, open‐label pilot study consisted of three treatment groups of four subjects each dosed as follows: group 1: 40 mg of nemifitide administered by standard needle/syringe and groups 2 and 3: 40 and 80 mg nemifitide, respectively, administered by using a needle‐free (Bioject™) injection delivery system. Plasma concentrations of nemifitide were determined by LC/MS/MS in blood samples collected at 10 min and 0.5, 1, 2, 4, 6 and 24 h after dosing. PK parameters, including observed Cmax, Tmax and AUC0−24, were calculated and statistical analysis of the data was conducted. Safety assessments (dosing site evaluations) were done at 0.5, 1, 5 and 24 h after dosing. Vital signs and clinical laboratory tests were taken on day 1 prior to dosing and at 24 h post‐dose. Adverse experiences in all subjects were observed only as drug‐related local reactions at the injection sites. All were considered mild in severity and transient (resolved by 24 h after dosing). Tmax was observed at 10 min after dose and was the same in all subjects. In the three dosing groups, 1 (40 mg), 2 (40 mg) and 3 (80 mg), observed Cmax values were 226, 245 and 440 ng/ml, respectively, and AUC0−24 values were 108, 106 and 205 ng·h/ml, respectively. Ratios of AUC0−24 and observed Cmax for nemifitide in plasma between groups 1 and 2 were within the 80%–125% range, indicating that the two modes of drug administration resulted in similar systemic exposure to nemifitide. Pharmacokinetic parameters (AUC0−24 and Cmax) indicate dose‐proportionality between the doses of 40 and 80 mg. Copyright © 2005 John Wiley & Sons, Ltd.
Influence of sucrose and water content on molecular mobilityin starch‐based glasses as assessed through structureand secondary relaxation
Authors: Poirier‐Brulez Fabienne , Roudaut Gaëlle , Champion Dominique , Tanguy Marie , Simatos Denise 
Published: August 2005

AbstractMolecular mobility is known to be a key parameter in controlling the physical properties of materials and thus their quality and performance. Beyond glass transition related changes, attention should be called to the impact of local motions remaining in the glassy state. Gelatinized waxy maize starch at different sucrose contents (0–20% solids) was equilibrated between 0 and 14% water and sorption isotherms determined at 25°C. The effect of water and sucrose content on the molecular mobility of glassy starch was investigated by differential scanning calorimetry through enthalpy relaxation studies and dynamical mechanical thermal analysis. The existence of sucrose–starch interactions was suggested by the sorption isotherms not following the expected additivity of the single component sorption curves. Contrary to the glass transition or associated α relaxation, water and sucrose affected differently the secondary relaxations. Indeed, the β relaxation observed around −15°C was shifted to lower temperature upon increasing hydration, and to higher temperature when sucrose content increased, suggesting a hindering of these local motions. Enthalpy relaxation of the ternary mixtures was studied following aging up to 668 h at Tg −15°C. Ternary mixtures exhibited an enthalpy relaxation upon aging lower than starch alone as a sign of lower polymer mobility in the presence of small molecules, contrary to the free volume theory. Relaxation kinetics were characterized with the Cowie–Ferguson model and compared to literature data. The extent of the enthalpy relaxation appeared to be controlled by the distance between the aging temperature and the β relaxation temperature. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 63–73, 2006This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Interaction of heme proteins with poly(propyleneimine) dendrimers in layer‐by‐layer assembly films under different pH conditions
Authors: He Pingli , Li Min , Hu Naifei 
Published: August 2005

AbstractWith the isoelectric point at pH 7.4, hemoglobin (Hb) has net positive surface charges at pH 5.0 and overall negative charges at pH 9.0, and is essentially neutral at pH 7.0. The fifth‐generation poly(propyleneimine) (PPI) dendrimer is usually positively charged in aqueous solution. The {PPI/Hb}n films under different pH conditions have been successfully fabricated on various solid surfaces by the layer‐by‐layer assembly technique, and the growth of films was monitored by ultraviolet‐visible (UV‐vis) spectroscopy, quartz crystal microbalance (QCM), and cyclic voltammetry (CV). Not only was the negatively charged Hb at pH 9.0 alternately adsorbed with positively charged PPI onto solid substrates by electrostatic attraction between them, but the positively charged Hb at pH 5.0 was also successfully assembled with like charged PPI into layer‐by‐layer {PPI/Hb(pH 5.0)}n films. For the latter, the localized electrostatic interaction or the charge reversal of proteins on PPI surface may be the main driving force. For {PPI/Hb(pH 7.0)}n films, however, the hydrophobic/hydrophilic interaction may play a more important role in the assembly, making the amount of adsorbed Hb even less than that of {PPI/Hb(pH 5.0)}n films. For comparison, negatively charged catalase (Cat) at pH 8.0 was used to assemble layer‐by‐layer films with positive PPI, but {PPI/Cat}n films showed quite different properties from {PPI/Hb}n films. UV‐vis and infrared (IR) spectroscopy, QCM, ellipsometry, and voltammetry were utilized to characterize the {PPI/protein}n films. The results suggest that the proteins in the multilayer films retain their near‐native structure and display good voltammetric response for heme Fe(III)/Fe(II) redox couples at underlying pyrolytic graphite (PG) electrodes. Electrocatalysis of oxygen and hydrogen peroxide based on direct electrochemistry of heme proteins at {PPI/protein}n film electrodes was also demonstrated. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 310–323, 2005This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Improvement of domain linker prediction by incorporating loop‐length‐dependent characteristics
Authors: Tanaka Takanori , Yokoyama Shigeyuki , Kuroda Yutaka 
Published: August 2005

AbstractProtein dissection into structural domains that can fold in isolation is an important issue in both functional and structural proteomics. Here, we analyzed inter‐ and intradomain loop sequences (respectively named domain linker and nonlinker loops) and computed a domain linker likelihood score, which was used for developing a domain boundary prediction protocol. The analysis confirmed our previous results indicating that the amino acid composition in terms of glycine, proline, aspartic acid, asparagine, lysine, and histidine significantly differs between linker and nonlinker loops. However, a detailed examination revealed that the amino acid composition bias actually depends on the loop length. Indeed, significant frequency deviations were observed for glycine, proline, and aspartic acid in short linker and nonlinker loops, whereas deviations were observed for aspartic acid, proline, asparagine, and lysine in long linker and nonlinker loops. Finally, we incorporated this loop‐length‐dependent amino acid composition bias in a simple linker prediction protocol, which predicted linkers with a 40.6% specificity and a 36.1% sensitivity. These figures are 4.4 and 2.4% higher than those obtained with our former prediction protocol that does not incorporate loop‐length‐dependent characteristics. This result should have practical significance for experimental protein dissection, since the probability of obtaining a stably folding structural domain by randomly dissecting a protein sequence is estimated to be 12.6%. © 2005 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 161–168, 2006This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Monte Carlo simulation of protein folding in the presence of residue‐specific binding sites
Authors: Rossinsky E. , Srebnik S. 
Published: August 2005

AbstractEnsemble growth Monte Carlo (EGMC) and dynamic Monte Carlo (DMC) simulations are used to study sequential folding and thermodynamic stability of hydrophobic–polar (HP) chains that fold to a compact structure. Molecularly imprinted cavities are modeled as hard walls having sites that are attractive to specific polar residues on the chain. Using EGMC simulation, we find that the folded conformation can be stabilized using a small number of carefully selected residue‐specific sites while a random selection of surface‐bound residues may only slightly contribute toward stabilizing the folded conformation, and in some cases may hinder the folding of the chain. DMC simulations of the surface‐bound chain confirm increased stability of the folded conformation over a free chain. However, a different trend of the equilibrium population of folded chains as a function of residue‐external site interactions is predicted with the two simulation methods. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 259–268, 2005This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Prospective analysis of patients with adenocarcinoma of the gastric cardia and lymph node metastasis in the proximal field of the chest
Authors: Lagarde S M , Cense H A , Hulscher J B F , Tilanus H W , Ten Kate F J W , Obertop H , van Lanschot J J B 
Published: August 2005

Abstract

Background
The extent to which adenocarcinoma of the cardia with lymph node metastasis in the upper mediastinum is amenable to cure by radical surgery is open to debate. It remains unclear whether these relatively distant metastases have an effect on long-term survival. The aim of this study was to identify the incidence of such positive nodes and evaluate their prognostic significance.

Methods
Some 50 patients with adenocarcinoma of the gastric cardia and substantial invasion of the oesophagus (junctional type II), who underwent an extended transthoracic oesophagectomy as part of a prospective randomized trial between 1994 and 2000, were studied.

Results
Eleven patients (22 per cent) had lymph node metastasis in the proximal field of the chest. These patients had more positive nodes overall (P = 0·020) and a shorter median survival (P = 0·009) than those without such metastasis. Multivariate analysis identified positive nodes in the proximal field as an independent predictor of poor survival.

Conclusion
Lymph node metastasis in the proximal field of the chest is common and is an indicator of poor prognosis in patients with adenocarcinoma of the cardia.
The Mechanism of Formamide Hydrolysis in Water from Ab Initio Calculations and Simulations
Authors: Gorb Leonid , Asensio Amparo , Tuñón Iñaki , Ruiz‐López Manuel F. 
Published: August 2005

AbstractThe neutral hydrolysis of formamide in water is a suitable reference to quantify the efficiency of proteolytic enzymes. However, experimental data for this reaction has only very recently been obtained and the kinetic constant determined experimentally is significantly higher than that predicted by previous theoretical estimations. In this work, we have investigated in detail the possible mechanisms of this reaction. Several solvent models have been considered that represent a considerable improvement on those used in previous studies. Density functional and ab initio calculations have been carried out on a system which explicitly includes the first solvation shell of the formamide molecule. Its interaction with the bulk has been treated with the aid of a dielectric continuum model. Molecular dynamics simulations at the combined density functional/molecular mechanics level have been carried out in parallel to better understand the structure of the reaction intermediates in aqueous solution. Overall, the most favored mechanism predicted by our study involves two reaction steps. In the first step, the carbonyl group of the formamide molecule is hydrated to form a diol intermediate. The corresponding transition structure involves two water molecules. From this intermediate, a water‐assisted proton transfer occurs from one of the hydroxy groups to the amino group. This reaction step may lead either to the formation of a new reaction intermediate with a marked zwitterionic character or to dissociation of the system into ammonia and formic acid. The zwitterionic intermediate dissociates quite easily but its lifetime is not negligible and it could play a role in the hydrolysis of substituted amides or peptides. The predicted pseudo‐first‐order kinetic constant for the rate‐limiting step (the first step) of the hydrolysis reaction at 25 °C (3.9×10−10 s−1) is in excellent agreement with experimental data (1.1×10−10 s−1).
Triple Hydrogen Bonds Direct Crystal Engineering of Metal‐Assembled Complexes: The Effect of a Novel Organic–Inorganic Module on Supramolecular Structure
Authors: Adachi Keiichi , Sugiyama Yuichi , Yoneda Ko , Yamada Koichi , Nozaki Koichi , Fuyuhiro Akira , Kawata Satoshi 
Published: August 2005

AbstractNovel triply hydrogen bonded suprastructures based on [M(tdpd)2(L)2]2− (H2tdpd=1,4,5,6‐tetrahydro‐5,6‐dioxo‐2,3‐pyrazinedicarbonitrile, L=solvent) and melamine‐analogous cations have been synthesized and characterized. The use of anions containing two AAA sets from [M(tdpd)2(L)2]2− together with cations containing one DDD set (A=hydrogen‐bond acceptor, D=hydrogen‐bond donor) leads to the formation of complementary triply hydrogen bonded modules in the solid state. In all cases, the building module is further extended via additional hydrogen‐bonding interactions to produce a tape, and tapes are assembled into sheets. These results show that a hydrogen‐bonded module consisting of different kinds of building blocks, one of which is a metal complex that includes hydrogen‐bond acceptor sites and the other is a hydrogen‐bond donor molecule, will be attractive for constructing metal‐containing supramolecular systems by the self‐assembly technique.
Rh‐Catalyzed Asymmetric Hydrogenation of Prochiral Olefins with a Dynamic Library of Chiral TROPOS Phosphorus Ligands
Authors: Monti Chiara , Gennari Cesare , Piarulli Umberto , de Vries Johannes G. , de Vries André H. M. , Lefort Laurent 
Published: August 2005

AbstractA library of 19 chiral tropos phosphorus ligands, based on a flexible (tropos) biphenol unit and a chiral P‐bound alcohol (11 phosphites) or secondary amine (8 phosphoramidites), was synthesized. These ligands were screened, individually and as a combination of two, in the rhodium‐catalyzed asymmetric hydrogenation of dehydro‐α‐amino acids, dehydro‐β‐amino acids, enamides and dimethyl itaconate. ee values up to 98 % were obtained for the dehydro‐α‐amino acids, by using the best combination of ligands, a phosphite [4‐P(O)2O] and a phosphoramidite [13‐P(O)2N]. Kinetic studies of the reactions with the single ligands and with the combination of phosphite [4‐P(O)2O] and phosphoramidite [13‐P(O)2N] have shown that the phosphite, despite being less enantioselective, promotes the hydrogenation of methyl 2‐acetamidoacrylate and methyl 2‐acetamidocinnamate faster than the mixture of the same phosphite with the phosphoramidite, while the phosphoramidite alone is much less active. In this way, the reaction was optimized by lowering the phosphite/phosphoramidite ratio (the best ratio is 0.25 equiv phosphite/1.75 equiv phosphoramidite) with a resulting improvement of the product enantiomeric excess. A simple mathematical model for a better understanding of the variation of the enantiomeric excess with the phosphite/phosphoramidite ratio is also presented.
A Highly Directional Fourfold Hydrogen‐Bonding Motif for Supramolecular Structures through Self‐Assembly of Fullerodendrimers
Authors: Hahn Uwe , González Juan J. , Huerta Elisa , Segura Margarita , Eckert Jean‐François , Cardinali François , de Mendoza Javier , Nierengarten Jean‐François 
Published: August 2005

AbstractSupramolecular dendrimers resulting from the dimerization of fullerene‐functionalized dendrons through a quadruple hydrogen‐bonding motif were prepared. The synthetic strategy is based on the esterification of a tert‐butoxycarbonyl (Boc)‐protected 2‐ureido‐4‐[1H]pyrimidinone precursor possessing an alcohol function with fullerodendrons bearing a carboxylic acid unit at the focal point. Subsequent acidic treatment to cleave the protecting group and reaction of the resulting amine with octylisocyanate affords the targeted compounds. As demonstrated by the results of MALDI‐TOF mass spectrometry and 1H NMR spectroscopy, both of the 2‐ureido‐4‐[1H]pyrimidinone derivatives form self‐assembled dimers spontaneously through hydrogen‐bonding interactions, thus leading to supramolecular structures containing two or ten fullerene moieties.