bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellulose fibers modified by silicon dioxide nanoparticles
Authors: Kulpinski Piotr 
Published: August 2005

AbstractThe sol–gel method is one of the most suitable ways for producing glasses, glass films, glass fibers, and glass nanoparticles. The relatively mild reaction conditions and simplicity of the sol–gel method make it an excellent tool for producing substances with precisely tailored properties. This technique opens the possibility for the synthesis of various new compounds, including pH sensors, ion sensors, bioactive nanoparticles, dyes carriers, and so forth. An attempt was made to combine the sol–gel technique with the advanced technology in the production of cellulose fibers in order to obtain fibers with new and unique properties. Cellulose fibers were prepared with N‐methylmorpholine‐N‐oxide as the direct solvent. The obtained fibers contained up to 30% (w/w) silicon dioxide nanoparticles. In order to observe the influence of the modifier on the fibers, their mechanical properties were examined. Modified fibers were also examined by means of thermogravimetry, wide‐angle X‐ray scattering, and 29Si‐NMR solid‐state spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1793–1798, 2005
Changes induced in silk‐like polyester properties by alkoxides treatment
Authors: Raslan W. M. , Bendak A. 
Published: August 2005

AbstractThe action of alkali treatment in both aqueous and alcoholic media is investigated to attain silk‐like polyester fabric. The use of alkoxide solutions is more effective on polyester fabric. Rapid loss in weight up to 15–20% occurs at ambient conditions. Immersion and padding techniques are applied. The effect of treatment on some properties of polyester fabric are given through measurements of tensile strength, drapability, permeability, density gradient, crystallinity, thermogravimetric analysis, and scanning electron microscopy. Optimization of the treatment conditions is also suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1829–1837, 2005
Thermal aging properties and chemical resistance of blends of natural rubber and epoxidized low molecular weight natural rubber
Authors: Akinlabi A. K. , Okieimen F. E. , Aigbodion A. I. 
Published: August 2005

AbstractStudies into solvent resistance and aging properties of blends of natural rubber and epoxidized low molecular weight natural rubber were carried out. Vulcanization of the blends using the semi‐efficient vulcanization (semi‐EV) system was found to have curing advantages over conventional vulcanization (CV) and efficient vulcanization (EV) systems. The rheological properties (cure time, t90, and scorch time, t2), solvent resistances, and aging properties of the vulcanizates were found to improve as the level of epoxidized low molecular weight natural rubber in the blends increases. The mechanical properties of the blends were also found to be within the accepted level for NR vulcanizates. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1733–1739, 2005
Morphological and electromechanical studies of fibers coated with electrically conductive polymer
Authors: Xue P. , Tao X. M. 
Published: August 2005

AbstractElectrically conductive fibers have been prepared by polymerization of pyrrole on surfaces of commercial polymer fibers. Thickness and morphology of the conducting thin film on the surface of the fibers were examined by scanning probe microscopy, indicating a strong dependence of the substrate's nature, in addition to the processing conditions. Electromechanical property was investigated by an electromechanical testing system, showing that a smooth and uniform coating and the matched mechanical properties will lead to a satisfied performance of conductive fiber sensors. The difference in the behavior of two types of composite fibers was investigated by scanning electron microscopy in situ observations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1844–1854, 2005
Static uniaxial compression of polyisoprene–montmorillonite nanocomposites monitored by 1H spin–lattice relaxation time constants
Authors: Poliskie G. M. , Cohen R. E. , Gleason K. K. 
Published: August 2005

AbstractPrevious work has focused on the use of microscopy to explore the mechanisms of deformation in polymer nanocomposites. That technique creates a qualitative representation that may not be statistically representative of the bulk properties. This paper illustrates the utility of solid‐state NMR, which inherently measures bulk behavior, to both identify and quantify mechanisms of deformation. Specifically, in this study, increases in the interfacial area of various modifications of Cloisite clay in 1,4‐cis polyisoprene nanocomposites were monitored during uniaxial compression. Interaction of the Fe+3 in the clay with the polymer decreases the polymer's 1H spin–lattice relaxation time constant (T1). In some of the nanocomposites, the increase in the interfacial area of the clay platelets was observed by a decrease in the polymer's T1 with successive amounts of strain. The observation of these changes with static 1H‐NMR is limited by the dispersion of the clay. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1806–1813, 2005
DNA‐loaded porous polyethersulfone particles for environmental applications II. Utilization
Authors: Zhao Changsheng , Yang Kaiguang , Wen Xian , Li Fan , Zheng Benxiang , Nomizu Motoyoshi , Nishi Norio 
Published: August 2005

AbstractDNA‐loaded porous polyethersulfone (PES) particles are fabricated using a liquid–liquid phase separation technique. The particles are then used for environmental applications. Both the DNA‐loaded porous PES particles and the DNA‐loaded PES porous particle column could accumulate and remove DNA intercalating pollutants, such as ethidium bromide, acridine orange, endocrine disruptors, and heavy metal ions. The microsphere column shows more high removal efficiency. These results proved that the DNA‐loaded porous particles have the potential to serve as absorbents for environmental applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1674–1678, 2005
Biodegradable polymers based on renewable resources VIII. Environmental and enzymatic degradability of copolycarbonates containing 1,4 : 3,6‐dianhydrohexitols
Authors: Yokoe Makito , Aoi Keigo , Okada Masahiko 
Published: August 2005

AbstractEnvironmental and enzymatic degradations were investigated on a series of copolycarbonates consisting of equimolar amounts of 1,4 : 3,6‐dianhydrohexitols (1,4 : 3,6‐dianhydro‐D‐glucitol (1a) and 1,4 : 3,6‐dianhydro‐D‐mannitol (1b)) and alkylene diols (1,4‐butanediol, 1,6‐hexanediol, 1,8‐octanediol, and 1,10‐decanediol) or oligo(ethylene glycol)s (di‐, tri‐, and tetraethylene glycols). Fourteen different copolycarbonates with number average molecular weights in the range of 1.1–4.2 × 104 were prepared by solution polycondensation as described in our previous article. Biodegradability of the copolycarbonates was assessed by soil burial degradation tests in composted soil at 27 °C and by enzymatic degradation tests in a phosphate buffer solution at 37 °C. In general, biodegradability of the copolycarbonates increased with increasing chain lengths of the methylene groups of alkylene diols or of the oxyethylene groups of the oligo(ethylene glycol)s. SEM observations of the film surfaces of polymers recovered from soil burial indicated that the copolycarbonates were degraded by microorganisms in soil. In enzymatic degradation, the copolycarbonates containing alkylene diol components showed high degradability with Pseudomonas sp. lipase, whereas the copolycarbonates containing oligo(ethylene glycol) components were not degraded at all. The enzymatic degradability of the copolycarbonates is discussed with reference to the geometrical structure around the carbonate linkages and the microstructure and hydrophobicity of the polymer chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1679–1687, 2005
Vulcanization kinetics of nitrile rubber/layered clay nanocomposites
Authors: Choi Dongcheol , Kader M. Abdul , Cho Baik‐Hwan , Huh Yang‐il , Nah Changwoon 
Published: August 2005

AbstractCure kinetic studies on nitrile rubber(NBR)‐layered clay nanocomposites, prepared by a melt mixing process, was investigated using a cure rheometer and differential scanning calorimeter (DSC). The characterization of the structure of the nanocomposites of uncured and cured samples was performed using X‐ray diffraction. The results showed that the interlayer spacing of cured nanocomposites was smaller than that of the uncured sample due to partial removal of organoclay from the interlayer spacing. The cure characterization showed a marked decrease in the scorch time of the NBR/organoclay system without affecting the optimum cure time and torque values due to the accelerating and plasticizing effect of organoclay. DSC analysis showed a reduction in cure time and increase in enthalpy of curing for the compounds added with organoclay. There was a little change in cure behavior of the NBR/unmodified clay system. NBR/clay nanocomposite showed the suitability of autocatalytic model for analyzing the cure parameters of rubber/clay nanocomposites. The activation energy of curing of NBR/O‐MMT nanocomposites was lower than that of pristine NBR. The kinetic parameters determined from the model equation showed close fitting with the experimental results, indicating the suitability of autocatalytic model for cure characterization. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1688–1696, 2005
Synthesis and photopolymerization of oxetanes derived from bisphenol A
Authors: Verstegen E. J. K. , Kloosterboer J. G. , Lub J. 
Published: August 2005

AbstractA series of new dioxetanes derived from bisphenol A has been synthesized. Polymers were obtained by photopolymerization. The polymerization shrinkage of these relatively fast polymerizing dioxetane monomers was <3%, much less than that of dimethacrylates of a comparable molecular weight. The rates of polymerization compare favorably with that of the diglycidylether of bisphenol A, which also exhibits a low shrinkage. The relationship between the chemical structure and the temperature of maximum mechanical loss was investigated. Some of the new polymers exhibit temperatures of maximum mechanical loss sufficiently high to be useful for precision optical components made by photoreplication. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1697–1707, 2005
Degradation of acrylonitrile–ammonium itaconate copolymers
Authors: Hou Chen , Qu Rongjun , Qun Wang , Ying Liang , Wang Chengguo 
Published: August 2005

AbstractAcrylonitrile–ammonium itaconate copolymers were prepared by H2O/dimethyl formamide suspension polymerization technique. Differential scanning calorimetry results of the degradation of acrylonitrile–ammonium itaconate copolymers in air are presented. The apparent activation energy of degradation of the copolymer was calculated using the Kissinger method. Effects of copolymerization conditions on the apparent activation energy of copolymer were studied. Increasing the dimethyl formamide concentration in the solvent mixture leads to a rapid increase in the degradation apparent activation energy of acrylonitrile–ammonium itaconate copolymer. The value of the degradation apparent activation energy of the copolymer synthesized in dimethyl formamide solvent increases up to 168.3 kJ mol−1. The apparent activation energy decreases quickly along with an increase in ammonium itaconate concentration, and this change becomes less prominent as the weight ratio of ammonium itaconate/acrylonitrile goes beyond 6/94, ΔEa = 89.4 ± 2.0 kJ mol−1. The apparent activation energy shows a trend of increase with increasing copolymerization temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1708–1711, 2005
Synthesis and phase behavior of nematic liquid‐crystalline elastomers derived from smectic crosslinking agent
Authors: Jia Ying‐Gang , Zhang Bao‐Yan , He Xiao‐Zhi , Ning Jia‐Zun 
Published: August 2005

AbstractA mesogenic crosslinking agent M‐1 was synthesized to minimize the perturbations of nonmesogenic crosslinking agent for liquid‐crystalline elastomers. The synthesis of side‐chain liquid‐crystalline elastomers containing a rigid mesogenic crosslinking agent M‐1 and a nematic monomer M‐2 was described by a one‐step hydrosilylation reaction. The chemical structures of the obtained monomers and network polymers were confirmed by Fourier transform infrared and 1H‐NMR spectroscopy. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the crosslinking units on the phase behavior was discussed. The liquid‐crystalline elastomers containing less than 15 mol % of the crosslinking units showed elasticity, reversible phase transition, and threaded texture. The experimental results demonstrated that isotropic temperature and liquid‐crystalline range of polymers P‐1–P‐7 decreased a little as the concentration of crosslinking agent M‐1 increased, and the use of mesomorphic crosslinking agent M‐1 promotes the arrangement of liquid‐crystalline units from P‐1 to P‐5. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1712–1719, 2005
Effect of concentrated sulfuric acid and nitroethane on insoluble residues in acetylating medium of cellulose acetate prepared from low grade pulps
Authors: Shashidhara G. M. , Guruprasad K. H. 
Published: August 2005

AbstractCellulose acetate was prepared from locally available low grade pulps containing α‐cellulose in the range of 79–94%. The chemical and spectroscopic characterization confirmed the acetylation of all the cellulosic sources studied in the work. The effect of concentrated sulfuric acid as a catalyst and nitroethane as a solvent in the acetylation medium in reducing the insoluble residues was studied. The gravimetric analysis has indicated that these reagents reduce the insoluble residues. This was further confirmed by the optical microscopic photographs. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1765–1771, 2005
Synthesis and Reactions of Some New Substituted Pyridine and Pyrimidine Derivatives as Analgesic, Anticonvulsant and Antiparkinsonian Agents
Authors: Amr Abd El‐Galil E. , Sayed Hayam H. , Abdulla Mohamed M. 
Published: August 2005

AbstractA series of substituted pyridine and pyrimidine derivatives were synthesized as analgesic, anti convulsant, and antiparkinsonian agents by using compounds 1, 2, and 9 as starting materials. Pyr idino‐imide derivative 3 was prepared by condensation of 1 with tetrachlorophthalic anhydride and compounds 4 and 5 were also obtained by reaction of compound 1 with 1,2,4,5‐benzene‐tetra carboxylic dianhydride and 1,4,5,8‐naphthalenetetracarboxylic dianhydride, respectively. Similarly, compound 2 was reacted with previous anhydrides to afford the corresponding imide 6 and bis‐imide derivatives 7 and 8, respectively. Bis‐arylmethylene derivatives 9 were treated with hydrogen peroxide to afford the corresponding bis‐oxiranocycloalkanone derivatives 10, which condensed with thiourea to give the corresponding thioxopyrimidine derivatives 11. Treatment of compound 11 with chloroacetic acid in the presence of anhydrous sodium acetate afforded the corresponding thiazolopyrim idine derivative 12 which condensed with aromatic aldehydes in acetic acid/acetic anhydride to give arylmethylene derivative 13. Also, compounds 13 could be prepared by reaction of compounds 11 with chloroacetic acid, aromatic aldehydes, and sodium acetate in a mixture of acetic acid and acetic anhydride. The pharmacological screening showed that many of these obtained compounds have good analgesic, anticonvulsant, and antiparkinsonian activities comparable to Valdecoxib, Carbamazepine, and Benzatropine as reference drugs.
Secondary conformation of short lysine‐ and leucine‐rich peptides assessed by optical spectroscopies: Effect of chain length, concentration, solvent, and time
Authors: Hernández Belén , Boukhalfa‐Heniche F.‐Z. , Seksek Olivier , Coïc Yves‐Marie , Ghomi Mahmoud 
Published: August 2005

AbstractSolution secondary structures of three synthetic cationic peptides, currently used in antisense oligonucleotide delivery into living cells, have been analyzed by means of circular dichroism (CD) and Raman scattering in different buffers as a function of concentration and time. All three peptides are of minimalist conception, i.e., formed by only two types of amino acids (leucine: L and lysine: K). Two of these peptides contain 15 aminoacids: Nter‐ KLLKLLLKLLLKLLK (L10K5), Nter‐KLKLKLKLKLKLKLK (L7K8), and the third one has only 9 residues: Nter‐KLKLKLKLK (L4K5). The conformational behavior of the 15‐mers in pure water differs considerably one from another. Although both of them are initially disordered in the 50–350 μM range, L10K5gradually undergoes a disordered toα‐helix transition for molecular concentrations above 100 μM. In all other solvents used, L10K5adopts a stableα‐helical conformation. In methanol and methanol/Tris mixture, nonnativeα‐helices can be induced in both KL‐alternating peptides, i.e., L7K8and L4K5. However, in major cases and with a time delay depending on peptide concentration,β‐like structures can be gradually formed in both solutions. In PBS and methanol/PBS mixture, the tendency for L7K8and L4K5is to form structures belonging toβ‐family. A discussion has been undertaken on the effect of counterions as well as their nature in the stabilization of ordered structures in both KL‐alternating peptides. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 8–19, 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
Effect of vitamins C and E on oxidative processes in human erythrocytes
Authors: Claro Ligia Maria , Leonart Maria Suely Soares , Comar Samuel Ricardo , do Nascimento Aguinaldo José 
Published: August 2005

AbstractThe oxidative action of 1 mmol l−1 phenylhydrazine hydrochloride (PH) was studied on human erythrocytes treated with the antioxidants vitamin C (vit. C) and vitamin E (vit. E). The erythrocytes were resuspended in PBS to obtain 35% cell packed volume, and then submitted to the oxidative action of PH for 20 min, with or without previous incubation for 60 min with vit. C or vit. E. Heinz bodies and methemoglobin formation by PH were inhibited in the presence of vit. C. At the concentration of 90 mmol l−1, vit. C, not only seemed to lose its antioxidant effect, but it also promoted an increase in methemoglobin formation. Vit. C (0.5–80 mmol l−1) did not protect against GSH depletion by PH. Vit. C alone produced insignificant hemolysis, but, in the presence of PH, the hemolysis indices were more accentuated. Heinz body formation by PH was inhibited in the presence of vit. E. Formation of methemoglobin induced by PH was decreased by vit. E (0.1–2 mmol l−1), although vit. E (3–80 mmol l−1) did not lower the concentration of methemoglobin and did not lead to the recovery of the GSH depleted by PH. The results obtained suggest that vit. C and vit. E contribute to the decrease in oxidative stress caused by PH. Copyright © 2005 John Wiley & Sons, Ltd.
No association between methylenetetrahydrofolate reductase C677T polymorphism and breast cancer
Authors: Hekim Nezih , Ergen Arzu , Yaylım İlhan , Yılmaz Hülya , Zeybek Ümit , Öztürk Oğuz , İsbir Turgay 
Published: August 2005

AbstractMethylenetetrahydrofolate reductase (MTHFR) is an enzyme (EC 1.5.1.20), that reduces 5,10‐methylenetetrahydrofolate to 5‐methyltetrahydrofolate, a carbon donor for the homocysteine to methionine conversion. MTHFR is a keyenzyme that regulates folate metabolism which has an important role in DNA synthesis, DNA repair and methylation.The association between MTHFR C677T polymorphism and breast cancer has been investigated in several previous studies. Some researchers have shown an association between C677T polymorphism and breast cancer, but not all researchers found this association however.This study was designed to investigate, in the Turkish population, the association of MTHFR C677T polymorphism and breast cancer. Forty women patients with breast cancer and 68 healthy women were included in the study. MTHFR gene polymorphism was determined by the PCR‐RFLP method. SPSS 10.0 for windows was used to determine statistical significance.No differences were observed in the distribution of MTHFR genotypes or allele frequencies in the cases versus the controls. It was found that the frequencies of MTHFR polymorphism were 55%, 40%, 5% for CC, CT, TT genotype in patients and 56%, 38%, 6% in healthy controls respectively. Furthermore, association was observed among family history, metastatic risk and MTHFR genotypes in patients.Our data fail to support a relationship between MTHFR C677T and the risk for breast cancer. It may be that there are ethnic differences in terms of this relationship. Copyright © 2005 John Wiley & Sons, Ltd.
Haloacyl Complexes of Boron, [(CF3)3BC(O)Hal]−(Hal=F, Cl, Br, I)
Authors: Finze Maik , Bernhardt Eduard , Willner Helge , Lehmann Christian W. 
Published: August 2005

AbstractThe haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]−(Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]−(Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3BC fragment. All borate anions [(CF3)3BC(O)Hal]−(Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B,13C,17O,19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space groupP2/c(no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6‐311+G(d)].
Molecular Scaffold for the Construction of Three‐Armed and Cage‐Like Receptors
Authors: Haberhauer Gebhard , Oeser Thomas , Rominger Frank 
Published: August 2005

AbstractAn efficient procedure was developed for the synthesis of the C3‐symmetric molecular scaffold 2. The latter can easily be converted by a single step into either the three‐armed receptors 11–16 or the cage‐like receptor 17. X‐ray structures were obtained for 2, 11, and 16, which are discussed in regard to their aptitude as receptor platforms. The interaction of the three‐armed receptors 12–16 and the cage‐like receptor 17 with phloroglucinol was investigated. In accordance with the conclusions obtained from molecular modeling and X‐ray crystallographic studies on the host–guest complexes, the three‐armed bipyridine receptor 16 exhibits, due to its induced fit, a larger association constant toward phloroglucinol than the cage 17. This new receptor system shows all of the positive features characteristic of 2,4,6‐trialkylbenzene receptor systems, such as conformational control by steric gearing, ready availability, and versatility in derivatization. These attributes, combined with the advantageous size of the components, allows this system to be readily tailored to provide receptors for larger, biologically important molecules.