bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetic and thermodynamic study of methanolysis of poly(ethylene terephthalate) waste powder
Authors: Mishra S , Goje A S 
Published: February 2003

AbstractDepolymerization of poly(ethylene terephthalate) waste (PETW) was carried out by methanolysis using zinc acetate in the presence of lead acetate as the catalyst at 120–140 °C in a closed batch reactor. The particle size ranging from 50 to 512.5 µm and the reaction time 60 to 150 min required for methanolysis of PETW were optimized. Optimal percentage conversion of PETW into dimethyl terephthalate (DMT) and ethylene glycol (EG) was 97.8% (at 120 °C) and 100% (at 130 and 140 °C) for the optimal reaction time of 120 min. Yields of DMT and EG were almost equal to PET conversion. EG and DMT were analyzed qualitatively and quantitatively. To avoid oxidation/carbonization during the reaction, methanolysis reactions were carried out below 150 °C. A kinetic model is developed and the experimental data show good agreement with the kinetic model. Rate constants, equilibrium constant, Gibbs free energy, enthalpy and entropy of reaction are also evaluated at 120, 130 and 140 °C. The methanolysis rate constant of the reaction at 140 °C (10.3 atm) was 1.4 × 10−3 g PET mol−1 min−1. The activation energy and the frequency factor for methanolysis of PETW were 95.31 kJ mol−1 and 107.1 g PET mol−1 min−1, respectively.© 2003 Society of Chemical Industry
Synthesis and electroluminescent properties of a novel copolymer with short alternating conjugated and non‐conjugated blocks
Authors: Wang Haiqiao , Sun Qingjiang , Li Yongfang , Duan Lian , Qiu Yong , Li Xiaoyu 
Published: February 2003

AbstractA new electroluminescent copolymer [poly(1,5‐di(3,5‐dimethyloxystyrylene)naphthalene‐block‐tri(ethylene oxide)) (DSN–TEO)], containing alternating rigid, conjugated light‐emitting units and flexible tri(ethylene oxide) ionic conductive units, was synthesized via the Wittig reaction. The polymer has fairly good solubility in chloroform, tetrahydrofuran, toluene, etc, and excellent film‐forming ability. The decomposition temperature and the glass transition temperature were 409 °C and 42.2 °C, respectively. A light‐emitting diode (LED) device with configuration ITO/PEDOT–PSS/DSN–TEO/Ca(Al) and light‐emitting electrochemical cell (LEC) device with ITO/DSN–TEO + PEO (LiTf)/Al were prepared, and the photoluminescence and electroluminescence (EL) properties were investigated. Efficient blue‐green light emission (EL maximum emissive wavelength at 508 nm) was found with onset voltage at 6 V. The maximum light efficiency was 0.107 cd A−1 at 20 V for LED, and the onset voltage 2.5 V and the maximum light efficiency was 4.2 cd A−1 at 2.8 V for LEC, respectively. The response time of the LEC was less than 5 s. The EL efficiency of LEC device was improved by 44 as compared with the relative LED device.© 2003 Society of Chemical Industry
Crosslinking of pressure sensitive adhesive based on water‐borne acrylate
Authors: Czech Z 
Published: February 2003

AbstractThis publication shows how the kind of crosslinking agents and their contents influence important properties of acrylic based pressure‐sensitive adhesive (PSA) dispersions such as tack, adhesion and cohesion. Synthesized PSAs based on acrylic polymers, containing 2‐ethylhexyl acrylate, butyl acrylate, vinyl acetate, styrene and acrylic acid are used in the preparation of self‐adhesive dispersions used as coating of polyethylene foams and poly(vinyl chloride) and polyester foils.© 2003 Society of Chemical Industry
Ultrasonic‐assisted dyeing: I. Nylon dyeability with reactive dyes
Authors: Kamel M M , El‐Shishtawy Reda M , Hanna H L , Ahmed Nahed S E 
Published: February 2003

AbstractThe use of ultrasonic power (38.5 KHz, 350 W) to assist the dyeability of nylon‐6 fibre with reactive dyes is reported. The effects of the different factors that may affect the dyeability of nylon‐6 fibre with Reactive Red 55 were simultaneously carried out under both ultrasonic power and conventional heating conditions. The colour strength values obtained for the dyed samples using ultrasonic power were higher than those obtained using conventional heating. Also, the effect of alkaline soaping treatment on dye fixation for the dyed fabrics with different reactive dyes, at both acidic and neutral pHs, is generally better with ultrasonic than with conventional heating. The overall results indicate that the enhancing effect is mainly attributed to the de‐aggregation of dye molecules, which leads to better dye diffusion and possible assistance for dye‐fibre covalent‐bond fixation. The results of wet fastness properties of the dyed fabrics reveal improvement using ultrasonic power dyeing relative to the conventional heating method.© 2003 Society of Chemical Industry
Ultrasonic‐assisted dyeing: II. Nylon fibre structure and comparative dyeing rate with reactive dyes
Authors: El‐Shishtawy Reda M , Kamel M M , Hanna H L , Ahmed Nahed S E 
Published: February 2003

AbstractComparative dyeing kinetics of nylon‐6 fibre with different reactive dyes using conventional and ultrasonic conditions are presented. The time/dye‐uptake isotherms are revealing the enhanced dye‐uptake in the second phase of dyeing (diffusion phase). The data of dyeing rate fit well with the integrated form of the first‐order rate equation and values of dyeing rate constant and half‐time of dyeing are discussed. Ultrasonic efficiency in accelerating the dyeing rate relative to conventional heating was examined for all dyes used to show that ultrasonics are most effective for a dyeing system which has difficulty in achieving high dye‐uptake. To clarify the role of fibre fine structure and whether it is affected during dyeing with ultrasonic waves, time‐dependent ultrasonic pre‐treatment of nylon‐6 fibres and its effect on the colour strength obtained is presented. X‐ray diffraction studies on nylon‐6 fibres conventionally and ultrasonically pre‐treated have shown that the percentage of fibre crystallinity has become higher in ultrasonically treated fibre in comparison with that of conventionally treated. Although the increased crystallinity of the fibre, which occurs simultaneously during the ultrasonic dyeing process, would retard dye uptake, it seems that the enhanced effect of power ultrasonic is high enough to overcome this side‐effect on the fibre.© 2003 Society of Chemical Industry
The effect of buffer concentration, pH and buffer ions on the degradation and drug release from polyglycolide
Authors: Hurrell Susan , Cameron Ruth E 
Published: February 2003

AbstractSamples of polyglycolide were degraded in various buffered solutions in order to investigate the effects of buffer concentration, pH and particular buffer ions on the hydrolysis reaction. The small‐angle X‐ray scattering profiles changed with degradation; long periods were calculated and their changes with degradation used as a measure of the degradation rate. The release of a model drug, theophylline, was also investigated under these different buffering conditions. In more concentrated buffer solutions theophylline was released slightly earlier and the samples began to swell sooner. Increasing the pH of the phosphate buffer also resulted in an earlier swelling and release of drug. These effects were attributed to the neutralisation and increased solubility of acidic degradation products in more concentrated or alkaline buffer solutions. When an imidazole–HCl rather than a phosphate or citrate–citric acid buffer system was used, swelling and drug release were accelerated, as imidazole catalysed the ester hydrolysis reaction. The results are interpreted within the context of a four‐stage model of PGA degradation.© 2003 Society of Chemical Industry
Microbial screening of copolymers of 2,4‐dichlorophenyl methacrylate with N‐vinylpyrrolidone: synthesis and characterization
Authors: Patel Mitesh B , Patel Dharmesh A , Ray Arabinda , Patel Rajni M 
Published: February 2003

AbstractCopolymers of 2,4‐dichlorophenyl methacrylate and hydrophilic monomer (N‐vinylpyrrolidone) were synthesized with different feed ratios using dimethylformamide as solvent and 2,2′‐azobisisobutyronitrile as initiator at 70 °C. The copolymers were characterized by IR spectrometry. Copolymer compositions were determined by UV spectrometry. The monomer reactivity ratios were determined by applying the conventional linearization method of Fineman‐Ross. Gel permeation chromatography was employed for determining molecular weights and polydispersity indexes. Thermogravimetric analyses of polymers were carried out in nitrogen atmosphere. Homo‐ and copolymers were tested for their antimicrobial properties against selected microorganisms.© 2003 Society of Chemical Industry
Modification of the thermal properties and crystallization behaviour of poly(ethylene terephthalate) by copolymerization
Authors: Kint Darwin P R , Muñoz‐Guerra Sebastián 
Published: February 2003

AbstractPoly(ethylene terephthalate) (PET) is a widely used polyester, which can be crystallized from the melt over a wide range of supercooling conditions or, alternatively, quenched into the amorphous state and, subsequently, crystallized by thermal treatment above the glass‐transition temperature. It is well known that the crystallization of PET can be hindered by means of copolymerization or reactive blending. The incorporation of comonomeric units into the polymer backbone leads to an irregular chain structure and thereby inhibits regular chain packing for crystallization. The crystallization of PET copolyesters is strongly influenced by the chain microstructure regarding comonomer distribution, randomness and length of the crystallizable ethylene terephthalate sequences. This paper is mainly devoted to the thermally induced crystallization behaviour of PET and to reviewing the efforts that have been made in the last decade to modify the glass‐transition and melting temperatures, the crystallinity and the crystallization rate of this polyester. Furthermore, some illustrative experimental data obtained from isothermal and non‐isothermal crystallization of PET are included in this study.© 2003 Society of Chemical Industry
Synthesis of charged linear and crosslinked maleic diester polymers with electron‐beam irradiation
Authors: Atta Ayman M , Arndt K‐F 
Published: February 2003

AbstractSeries of maleic mono‐ and diester monomers have been prepared by esterification of maleic anhydride with poly(ethylene glycol) having different molecular weights, and with n‐dodecyl alcohol. These monomers were copolymerized with 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) using different dose rates of electron‐beam irradiation ranging from 40 to 150 kGy. The synthesized copolymers were characterized by IR and 1H NMR analysis. Their aggregation behaviour and viscometric properties in aqueous solutions were investigated. The crosslinked copolymers were prepared in aqueous acidic solutions at pH 1 or in the presence of 1% of N,N‐methylene bisacrylamide (MBA) as crosslinking agent. The final equilibrium water content and swelling capacities for the prepared hydrogels were determined in aqueous solutions at pH = 1, 6.8 and 12 at 298 K. Swelling equilibria for the prepared hydrogels were carried out in aqueous solutions of NaCl, KCl, CaCl2, Na2SO4, K2SO4 and CaSO4 at concentrations ranging from 1 × 10−6 to 2 M at 298 K.© 2003 Society of Chemical Industry
Synthesis and characterization of cationic polymeric salts: derivatives of 2‐(dimethylamino)ethyl‐2‐methacrylate, containing oligomeric ethylene oxide side‐chains
Authors: Stålgren J J R , Pamedytyte V , Makuska R , Claesson P M , Brown W , Jacobsson U 
Published: February 2003

AbstractA novel set of cationic polyelectrolytes has been prepared. The polyelectrolytes have a high cationicity with each segment carrying one positively charged quaternary ammonium group. The polyelectrolytes also contain grafted oligo(ethylene oxide) (EO) chains. The grafted EO chains are, according to NMR measurements, six units long. The graft density of EO chains has been varied and polymers having approximately 100%, 20% and 10% of the segments with a grafted EO chain have been prepared. The obtained products were characterized using 1H and 13C NMR spectroscopy. Aqueous solutions of the cationic polymers were characterized by dynamic light‐scattering (DLS) measurements. It was found to be important to include a radical inhibitor to prevent crosslinking reactions during isolation and purification. In general the DLS measurements showed a bimodal size distribution. The majority of the polymers (about 75 wt%) were found to have a hydrodynamic radius of 6–8 nm, with the remaining polymers being dominated by a fraction with a hydrodynamic radius in the range 120–140 nm.© 2003 Society of Chemical Industry
Structure‐efficiency relationships of zwitterionic detergents as protein solubilizers in two‐dimensional electrophoresis
Authors: Tastet Christophe , Charmont Stéphane , Chevallet Mireille , Luche Sylvie , Rabilloud Thierry 
Published: February 2003

AbstractSeveral zwitterionic detergents differing in their polar heads, linker parts and hydrophobia tail were synthesized and evaluated for their efficiency in protein solubilizers for two‐dimensional electrophoresis. A model system consisting of human red blood cell ghosts was used for this purpose. This study leads to the description of several new efficient detergents and allowed us to derive structural constraints for the design and synthesis of efficient detergents for two‐dimensional electrophoresis. These constraints apply to the hydrophilic head (sulfobetaine but not carboxybetaine), to the hydrophobic tail (12 to 16 alkyl carbons long, linear alkyl or alkylaryl) and to the presence and nature of the linker between the hydrophilic head and hydrophobic tail.
Peptidomics: A new approach to affinity protein microarrays
Authors: Scrivener Elaine , Barry Richard , Platt Albert , Calvert Robert , Masih George , Hextall Patrick , Soloviev Mikhail , Terrett Jonathan 
Published: February 2003

AbstractProtein microarrays for diagnostic and proteomic analyses are being developed using a number of different techniques for each of the steps required including immobilisation methods, assay and detection systems. This is extremely different to the development of DNA microarrays which is now a well established technology that has demonstrated the capabilities of transcriptomics to deliver validated differential transcripts. As mRNA and protein levels do not always correlate, protein microarrays would seem to be an obvious successor to DNA arrays. Unlike nucleic acids, however, protein targets are typically nonhomogeneous in physicochemical properties and affinity capture agents are often poorly characterised making the experiments difficult to perfect and reproduce. Moreover, running multiple affinity assays in parallel (multiplexing) is compromised by the heterogeneity of antibody affinities to their protein targets. In the peptidomic approach presented here the assayed mixture of proteins is enzymatically digested prior to affinity capture to form a mixture of short peptides that are more similar in their physicochemical properties than intact proteins. These peptides can be predicted by in silico digestion of individual proteins, e.g. from protein databases allowing design of nonhomologous reagents for the screening of affinity agent libraries. The use of mass spectrometry (e.g. matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry) for a direct confirmation of the identity of the species captured, provides a further advantage compared to the more usual method of detection in which fluorescently labelled captured species are scanned to give a spatially resolved image of the array.
VIRTUAL2D: A web‐accessible predictive database for proteomics analysis
Authors: Medjahed Djamel , Smythers Gary W. , Powell Douglas A. , Stephens Robert M. , Lemkin Peter F. , Munroe David J. 
Published: February 2003

AbstractThe available archive of sequence databases compiled from whole genome projects and budding proteomics efforts have enabled us to develop VIRTUAL2D, an interactive system for the assembly of virtual protein expression maps computed on the basis of theoretical isoelectric focusing point, molecular weight, tissue specificity and relative abundance for any set of proteins currently catalogued. This tool will assist in the preliminary, albeit putative, prediction of the identity and location of unknown and/or low abundance proteins in experimentally derived two‐dimensional polyacrylamide gel electrophoresis maps.
Mass spectrometry analysis of CD4‐associating proteins using affinity chromatography and affinity tag‐mediated purification of tryptic peptides
Authors: Bernhard Oliver K. , Burgess Jennifer A. , Hochgrebe Tim , Sheil Margaret M. , Cunningham Anthony L. 
Published: February 2003

AbstractThe study of protein interactions using mass spectrometry (MS) for identification of the components of purified protein complexes is leading to the description of increasingly valuable data on protein function. Commonly proteins in a given complex are identified via MS analysis of in‐gel digests of gel electrophoretically separated proteins. In this study, we have evaluated the use of an approach employing the digest of the whole protein complex to identify directly the proteins present in a purification of the CD4 receptor complex. We used a cysteinyl affinity capture method to reduce the complexity of the peptide mixture that was obtained from the tryptic digest of the whole protein complex to the rather limited mixture of only cysteine‐containing peptides. Here we report the use of this approach with MS for identification of the CD4 receptor complex components CD4 and p56lck, along with several other proteins present in the detergent‐solubilized fractions from the purification. We have been able to identify these proteins using peptide sequence data obtained from cysteine‐containing peptides. With appropriate control experiments, we have demonstrated the specific nature of the CD4‐p56lck interaction. In contrast, the other proteins identified are shown to arise from nonspecific interactions during the affinity chromatography purification suggesting a possible loss of specific interactions during the chromatography procedure. We found that the complexity of the mixture was reduced such that only 10% of the peptides derived from tryptic digest of the identified proteins were detected. This represents only one‐third of the cysteine‐containing peptides, however, suggesting that this approach does not enable detection of all individual proteins.
Identification of cellular changes associated with increased production of human growth hormone in a recombinant Chinese hamster ovary cell line
Authors: Van Dyk Derek D. , Misztal David R. , Wilkins Marc R. , Mackintosh James A. , Poljak Anne , Varnai Jodie C. , Teber Erdahl , Walsh Bradley J. , Gray Peter P. 
Published: February 2003

AbstractA proteomics approach was used to identify the proteins potentially implicated in the cellular response concomitant with elevated production levels of human growth hormone in a recombinant Chinese hamster ovary (CHO) cell line following exposure to 0.5 mM butyrate and 80 μM zinc sulphate in the production media. This involved incorporation of two‐dimensional (2‐D) gel electrophoresis and protein identification by a combination of N‐terminal sequencing, matrix‐assisted laser desorption/ionisation‐time of flight mass spectrometry, amino acid analysis and cross species database matching. From these identifications a CHO 2‐D reference map and annotated database have been established. Metabolic labelling and subsequent autoradiography showed the induction of a number of cellular proteins in response to the media additives butyrate and zinc sulphate. These were identified as GRP75, enolase and thioredoxin. The chaperone proteins GRP78, HSP90, GRP94 and HSP70 were not up‐regulated under these conditions.
Progress in the definition of a reference human mitochondrial proteome
Authors: Lescuyer Pierre , Strub Jean‐Marc , Luche Sylvie , Diemer Hélène , Martinez Pascal , Van Dorsselaer Alain , Lunardi Joël , Rabilloud Thierry 
Published: February 2003

AbstractOwing to the complexity of higher eukaryotic cells, a complete proteome is likely to be very difficult to achieve. However, advantage can be taken of the cell compartmentalization to build organelle proteomes, which can moreover be viewed as specialized tools to study specifically the biology and “physiology” of the target organelle. Within this frame, we report here the construction of the human mitochondrial proteome, using placenta as the source tissue. Protein identification was carried out mainly by peptide mass fingerprinting. The optimization steps in two‐dimensional electrophoresis needed for proteome research are discussed. However, the relative paucity of data concerning mitochondrial proteins is still the major limiting factor in building the corresponding proteome, which should be a useful tool for researchers working on human mitochondria and their deficiencies.
Diversity of puroindolines as revealed by two‐dimensional electrophoresis
Authors: Branlard Gérard , Amiour Nardjis , Igrejas Gilberto , Gaborit Thérèse , Herbette Stephane , Dardevet Mireille , Marion Didier 
Published: February 2003

AbstractPuroindolines are endosperm lipid binding proteins, which are separated by reversed phase‐high‐performance liquid chromatography or cation exchange chromatography into two isoforms, puroindoline‐a (PIN‐a) and puroindoline‐b (PIN‐b). Being very basic and close in molecular weight, PIN‐a and PIN‐b have never been separated using conventional isoelectric focusing and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). A two‐dimensional electrophoresis method, linear immobiline pH gradient (IPG×SDS‐PAGE), was developed, using 6–11 linear immobiline Dry Strips in the first dimension, which allowed the puroindolines to be focused between isoelectric point 10.5 and 11. Immunoblotting revealed that both PIN‐a and PIN‐b were each composed of several spots. Two‐dimensional patterns from unrelated wheat varieties revealed that several spots can be highlighted among varieties. Matrix‐assisted laser desorption/ionization‐time of flight spectrometry allowed the majority of the spots revealed in the puroindoline zone to be identified. The two‐dimensional IPG×SDS‐PAGE of these very basic wheat endosperm proteins, puroindolines and related grain softness proteins should facilitate the identification of the proteins associated with wheat endosperm texture that have a strong effect on milling, dough properties and end‐uses of wheats.
Proteomic analysis of the effect of heat stress on hexaploid wheat grain: Characterization of heat‐responsive proteins from total endosperm
Authors: Majoul Thouraya , Bancel Emmanuelle , Triboï Eugène , Ben Hamida Jeannette , Branlard Gérard 
Published: February 2003

AbstractHigh temperatures during grain filling have been reported to be one of the factors that can affect the dough properties and quality characteristics of wheat. Responses to high temperature have been related to changes in protein composition at both quantitative and qualitative levels. The present study was conducted to determine the influence of high temperature during grain filling on the protein composition of bread wheat evaluated by proteomic tools. Plants were grown in the field and transferred to cabinets soon after flowering. They were subjected to two thermal regimes 18°C/10°C (day/night) and 34°C/10°C. Total proteins were extracted from control grains and treated plants at three different post‐anthesis stages. The proteins were separated by two‐dimensional gel electrophoresis and analysed by Melanie 3 software. Of the total number of mature wheat grain proteins, 37 were identified as significantly changed by heat treatment. Analysis by matrix‐assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry coupled with database searching allowed the characterization of 25 heat‐induced proteins and only one heat‐decreased protein spot. To learn more about the function of the identified proteins, we examined their expression during treatment.