bluuebunny/crossref_metadata_2025_split huggingface dataset:
A methodology for the generation of low‐cost higher‐order methods for linear dynamics
Authors: Mancuso M. , Ubertini F. 
Published: February 2003

AbstractThis work presents a methodology which generates efficient higher‐order methods for linear dynamics by improving the accuracy properties of Nørsett methods towards those of Padé methods. The methodology is based on a simple and low‐cost iterative procedure which is used to implement a set of higher‐order methods with controllable dissipation. A sequence of improved solutions is obtained which correspond to algorithms offering an effective compromise between the efficiency of Nørsett methods and the accuracy of Padé methods. Moreover, a direct control over high‐frequency dissipation is possible by means of an algorithmic parameter. Numerical tests are reported which confirm that this set of algorithms is really attractive for linear dynamic analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Level set calculations of the evolution of boundaries on a dynamically adaptive grid
Authors: Sochnikov Vassili , Efrima Shlomo 
Published: February 2003

AbstractWe present a general algorithm for the study of the evolution of interfaces in growth processes based on the level set method, using the narrow band and the fast marching approximations, applied on a dynamically adaptive grid. A novel construction of a dynamical adaptive grid is presented. One important feature is that we establish a controllable finite‐width region of the highest resolution straddling the physically important boundary. This high‐resolution stripe provides a better description of the important physical variables. An efficient and robust coupling of a hierarchical space description structure with the state‐of‐the‐art level set method is established. Copyright © 2003 John Wiley & Sons, Ltd.
Boundary knot method for 2D and 3D Helmholtz and convection–diffusion problems under complicated geometry
Authors: Hon Y. C. , Chen W. 
Published: February 2003

AbstractThe boundary knot method (BKM) of very recent origin is an inherently meshless, integration‐free, boundary‐type, radial basis function collocation technique for the numerical discretization of general partial differential equation systems. Unlike the method of fundamental solutions, the use of non‐singular general solution in the BKM avoids the unnecessary requirement of constructing a controversial artificial boundary outside the physical domain. The purpose of this paper is to extend the BKM to solve 2D Helmholtz and convection–diffusion problems under rather complicated irregular geometry. The method is also first applied to 3D problems. Numerical experiments validate that the BKM can produce highly accurate solutions using a relatively small number of knots. For inhomogeneous cases, some inner knots are found necessary to guarantee accuracy and stability. The stability and convergence of the BKM are numerically illustrated and the completeness issue is also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Data structure and algorithms for fast automatic differentiation
Authors: Tsukanov I. , Hall M. 
Published: February 2003

AbstractIn this paper we discuss the data structure and algorithms for the direct application of generalized Leibnitz rules to the numerical computation of partial derivatives in forward mode. The proposed data structure provides constant time access to the partial derivatives, which accelerates the automatic differentiation computations. The interaction among elements of the data structure is explained by several numerical examples. The paper contains analysis of the developed data structure and algorithms. Copyright © 2003 John Wiley & Sons, Ltd.
An efficient artificial compressibility (AC) scheme based on the characteristic based split (CBS) method for incompressible flows
Authors: Nithiarasu P. 
Published: February 2003

AbstractIn this paper, an artificial compressibility scheme using the finite element method is introduced. 2002 Zienkiewicz Silver Medal and Prize winning paper. The multi‐purpose CBS scheme is implemented in its fully explicit form to solve incompressible fluid dynamics problems. It is important to note that the scheme developed here includes split and velocity correction. The proposed method takes advantage of good features from both velocity correction and standard artificial compressibility schemes. Unlike many other artificial compressibility schemes, the proposed one works on a variety of grids and gives results for a wide range of Reynold's numbers. The paper presents some bench mark two‐ and three‐dimensional steady and unsteady incompressible flow solutions obtained from the proposed scheme. Copyright © 2003 John Wiley & Sons, Ltd.
Influence of a zwitterionic surfactant on the chromogenic behavior of a dye‐containing aqueous PVA–polyether gel network
Authors: Kriwanek J. , Lötzsch D. , Vetter R. , Seeboth A. 
Published: February 2003

AbstractThe effect of the addition of a zwitterionic sulfobetaine to a dye‐containing polymer gel composed of two polymers – poly(vinyl alcohol) (PVA) and polyether – was investigated. With increasing sulfobetaine content a remarkable reduction of the UV‐vis‐absorption intensity of the longest wavelength absorption band of Phenol Red in the aqueous polymer network was observed, even for sulfobetaine concentrations below its critical micelle concentration (cmc). It can be assumed that this effect is based on the formation of ionic complexes between dye molecules and either single sulfobetaine molecules or aggregates of sulfobetaine. Furthermore, thermotropic behavior occurs in the investigated polymer gel system even at a polyether concentration as low as 0.8 wt%. Copyright © 2003 John Wiley & Sons, Ltd.
Structure–property relationships for film‐forming copoly(amide imide)s
Authors: Privalko Valery P. , Mudrak Claudia V. , Privalko Eleonora G. , Usenko Andriy A. , Pissis Policarpos 
Published: February 2003

AbstractThin films of copoly(amide imide)s (coPAIs) from dichloro‐dianhydride of trimellitimide‐N‐acetic acid and mixtures of diphenylmethane diamine (DPA) and cardo 9,9′‐bis‐phenylfluorene diamine (CDA) cast from solutions in dimethylacetamide (DMAA) were characterized by wide‐angle and small‐angle X‐ray scattering (WAXS and SAXS), dynamic mechanical thermal analysis (DMTA) (temperature interval: 293–703 K, frequency range: 1–100 Hz), and thermogravimetric analysis (TGA) (nitrogen flux, temperature interval: 303–973 K). The mean interchain spacings (WAXS) smoothly increased with the CDA/DPA molar ratio from 0.55 nm for CDA/DPA = 0/1 up to 0.60 nm for CDA/DPA = 1/0. The smooth patterns of the SAXS curves for all coPAIs were explained by the smearing‐out of electron density differences between densely‐packed and loosely‐packed microregions of coPAIs due to the wide dispersion of their sizes. The step‐like patterns of the TGA traces in the temperature intervals below and above 600 K were associated with successive weight losses due to the evaporation of residual water and of DMAA, and to the thermal degradation of diamine and dianhydride chain fragments, respectively. As could be inferred from the TGA data, the loosely‐packed regions comprise about 25–35% of the total volume of studied coPAIs. The mechanical relaxations observed in all coPAIs at Tβ < Tα′ < Tα (DMA) were attributed to the onset of non‐cooperative segment motion in loosely‐packed regions, of cooperative segment motion in loosely‐packed regions, and of cooperative segment motion in densely‐packed regions, respectively. At constant frequency, the sub‐glass relaxations were roughly composition‐independent, while chain‐stiffening effect was assumed to be responsible for the smooth increase of Tα′ and Tα, as well as of the corresponding apparent activation energies with the CDA/DPA ratio. Copyright © 2003 John Wiley & Sons, Ltd.
Protein adsorption and platelet adhesion of polysulfone membrane immobilized with chitosan and heparin conjugate
Authors: Yang M.‐C. , Lin W.‐C. 
Published: February 2003

AbstractPolysulfone (PSF) membranes were treated with ozone to introduce peroxides, and then grafted with either acrylic acid or chitosan, followed by the immobilization of heparin. The effect of spacer arm on blood compatibility was investigated using three chitosans of different molecular weight [1170 (water soluble), 160 000, and 400 000] and similar degrees of deacetylation (75%). The hydrophilicity was evaluated by measuring the contact angle of water. Blood compatibility was evaluated using the activated partial thromboplastin time (APTT) as well as the adhesion of platelets. The protein affinity was determined by the absorption of human serum albumin (HSA) and human plasma fibrinogen (HPF). The results show that by the coupling of chitosan, the amount of heparin immobilized can be increased by four times. Water contact angle (from 78 ° to 41 °) decreased with the increase of the amount of heparin immobilized, showing increased wettability. The heparinized PSF membrane showed longer APTT and decreasing platelet adhesion, compared to that of unmodified PSF membrane. The adsorption of HSA and HPF were reduced to 17 and 6%, respectively. This suggests that longer spacer binding to heparin can increase the opportunity of anti‐coagulation on contacting blood. These results demonstrated that the hydrophilicity and blood compatibility of PSF membrane could be improved by chitosan and heparin conjugate. Copyright © 2003 John Wiley & Sons, Ltd.
The preparation and characterization of novel cocylic(arylene disulfide) oligomers
Authors: Chen K. , Du X. S. , Meng Y. Z. , Tjong S. C. , Zhang Y. M. , Hay A. S. 
Published: February 2003

AbstractA series of homo‐ and cocyclic(arylene disulfide) oligomers were synthesized under high dilution conditions by the catalytic oxidation of arylenedithiols with oxygen in the presence of a copper‐amine catalyst in DMAc. The aryl groups contained moieties such as sulfone, ether, and ketone. The free radical ring‐opening polymerization of these cyclic(arylene disulfide) oligomers led to the formation of linear poly(thio arylene)s. The homo‐ and cocyclic(arylene disulfide) oligomers were characterized by gradient high pressure liquid chromatography (HPLC), get permeation chromatography (GPC), 1H‐NMR, and differential scanning calorimetry (DSC) methods. These cocyclic(arylene disulfide) oligomers except those containing sulfone moiety had lower melt flow temperature as low as 140 °C and therefore could readily undergo free radical ring‐opening polymerization under mild conditions. The glass transition temperatures of these cocyclics ranged from 72.3 to 190.0 °C, while the glass transition temperatures of the polydisulfides derived from these cocyclics ranged from 78.4 to 194.5 °C. In this article, a new method of preparing arylene dithiols 4,4′‐oxybis(benzenethiol) and diphenylmethane‐4,4′‐dithiol is reported. Copyright © 2003 John Wiley & Sons, Ltd.
Pyridinium chlorochromate oxidation route to polyaniline
Authors: Palaniappan S. , Amarnath C. A. 
Published: February 2003

AbstractIn this work, for the first time, pyridinium chlorochromate is used as an oxidizing agent inorder to oxidize aniline to polyaniline salts via an aqueous polymerization pathway in the presence of protic acids such as sulfuric, nitric, hydrochloric and phosphoric acid. The polymer samples were characterized by infrared, electronic absorption spectral, elemental analysis, conductivity, density and water absorption measurements. The results of the polyaniline salts prepared by pyridinium chlorochromate as an oxidizing agent were compared with that of the polyaniline salt prepared by ammonium persulfate. Generally, aniline is oxidized using ammonium persulfate as an oxidizing agent, which is unstable. In this work, pyridinium chlorochromate is used to oxidize aniline to polyaniline salt and the polymerization reaction could be completed in 30 min. Copyright © 2003 John Wiley & Sons, Ltd.
Synergistic mechanical behaviour and improved processability of poly(ether imide) by blending with poly(trimethylene terephthalate)
Authors: Ramiro J. , Eguiazábal J. I. , Nazábal J. 
Published: February 2003

AbstractFully miscible poly(ether imide) (PEI)/poly(trimethylene terephthalate) (PTT) blends were obtained by melt mixing in an extruder followed by injection moulding. The viscosity of PEI, represented by the pressure at the extruder output, almost halved upon the addition of only 10% PTT, allowing the use of PEI in applications where either complex parts or thin sections must be moulded. The modulus of elasticity showed a synergistic behaviour which was absolute (modulus higher than that of any of the two components) in the blend with 10% PTT. This was attributed mainly to the decrease in specific volume upon blending. The additional absolute synergism in the yield stress of PEI‐rich blends and their ductile nature depict a set of properties that make these new materials attractive in a number of new applications. Copyright ­© 2003 John Wiley & Sons, Ltd.
Mechanical, thermal and morphological behavior of bismaleimide modified polyurethane‐epoxy IPN matrices
Authors: Mahesh K. P. O. , Alagar M. , Ananda Kumar S. 
Published: February 2003

AbstractAn intercrosslinked network of bismaleimide modified polyurethane‐epoxy systems were prepared from the bismaleimide having ester linkages, polyurethane modified epoxy and cured in the presence of 4,4′‐diaminodiphenylmethane. Infrared spectral analysis was used to confirm the grafting of polyurethane into the epoxy skeleton. The prepared matrices were characterized by mechanical, thermal and morphological studies. The results obtained from the mechanical and thermal studies reveal that the incorporation of polyurethane into the epoxy skeleton increases the mechanical strength and decreases the glass transition temperature, thermal stability and heat distortion temperature. Whereas, the incorporation of bismaleimide having ester linkages into polyurethane modified epoxy systems increases the thermal stability, tensile and flexural properties and decreases the impact strength, glass transition temperature and heat distortion temperature. Surface morphology of polyurethane modified epoxy and bismaleimide modified polyurethane‐epoxy systems were studied using scanning electron microscopy. Copyright © 2003 John Wiley & Sons, Ltd.
Enhanced thermal properties and flame retardancy from a thermosetting blend of a phosphorus‐containing bismaleimide and epoxy resins
Authors: Jeng Ru‐Jong , Lo Geng‐Sheng , Chen Chih‐Ping , Liu Ying‐Ling , Hsiue Ging‐Ho , Su Wen‐Chiung 
Published: February 2003

AbstractEpoxy resins modified by an organosoluble phosphorus‐containing bismaleimide (3,3′‐bis(maleimidophenyl) ­phenylphosphine oxide; BMPPPO) were prepared by simultaneously curing epoxy/diaminodiphenylmethane (DDM), and BMPPPO. The resulted epoxy resins were found to exhibit glass transition temperatures as high as 212 °C, thermal stability at temperatures over 350 °C, and excellent flame retardancy with Limited oxygen index (LOI) values around 40. Incorporation of BMPPPO into epoxy resins via the thermosetting blend was demonstrated to be an effective way to enhance the thermal properties and flame retardancy simultaneously. Copyright © 2003 John Wiley & Sons, Ltd.
Improvement of gas meter performance using polymer materials
Authors: Kobayashi Hayao , Takamoto Masaki 
Published: February 2003

AbstractThe measuring elements of both dry‐ and wet‐type gas meters are composed of a diaphragm and rotary drum. In this article an explanation on the principle of measuring and the structure of the gas meter for each of these two types was discussed. Such applications were made as follows: synthetic rubber was used for the measuring diaphragm, engineering plastic was employed instead of metal for the measuring drum, and poly(butylene terephthalate) (PBT) was used for the casing, respectively. As a result, an improvement in the gas resistance performance and productivity, which led to a lighter weight, more compactness and a lower cost of productions was achieved. Also the influence of the solubility of the measured gas to the plastic on the measured valve was discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Regioselective end‐functionalization of polylactide oligomers with D‐glucose and D‐galactose
Authors: Bernard Katty , Degée Philippe , Dubois Philippe 
Published: February 2003

AbstractD‐glucose and D‐galactose end‐functionalized polylactide oligomers were synthesized by controlled ring‐opening polymerization of lactide using aluminium triisopropoxide, triethylaluminium or stannous octoate as promoter. Accordingly, two selectively protected monosaccharides were studied as co‐initiators, either 1,2;5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (1) and 1,2;3,4‐di‐O‐isopropylidene‐α‐D‐galactopyranose (2). In contrast to what is known in polymerization of ϵ‐caprolactone, both protected monosaccharides proved to be efficient co‐initiators and yielded end‐functionalized polylactide chains with controlled regioselectivity (C‐3 or C‐6 linkage), predictable molecular weights and narrow molecular weight distributions.© 2003 Society of Chemical Industry
Polyurethane and sulfonated polysulfone blend ultrafiltration membranes: II. Application studies
Authors: Malaisamy Ramamoorthy , Mohan Doraiswamy Raju , Rajendran Munnuswamy 
Published: February 2003

AbstractUltrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. Polyurethane‐ and sulfonated‐ polysulfone‐based membranes prepared in the absence and presence of the polymeric additive, poly(ethylene glycol) 600, in various compositions, were subjected to the rejection of macromolecular proteins, such as bovine serum albumin, egg albumin, pepsin and trypsin. Toxic heavy metal ions such as Cu2+, Ni2+, Cd2+ and Zn2+ were subjected to rejection by the blend membranes by complexing them with a polymeric ligand, polyethyleneimine. The effects of polymer blend compositions and additive concentrations on the rejection and permeate flux of both proteins and metal ions are discussed. The rejection and permeate flux efficiencies of the blend membranes are compared with pure sulfonated polysulfone membranes.© 2003 Society of Chemical Industry
On the stereochemical composition of poly(vinyl chloride) (PVC) and polypropylene (PP): a phenomenological study
Authors: Guarrotxena Nekane , Schue François , Collet André , Millán José‐Luis 
Published: February 2003

AbstractThe number of mmr‐ and rrm‐based structures which occur necessarily whenever an isotactic or a syndiotactic sequence breaks off respectively; the extent to which they are isolated or are extended to atactic sequences, and the fact that the mmr repeating sequence, especially when it takes the GTTG−TT conformation, is shorter and exhibits greater local free volume than rrm, mmm and rrr sequences, are shown to be the stereochemical composition determining structures in poly(vinyl chloride) (PVC) and polypropylene (PP) polymers. These structures, as analyzed by 13C NMR spectroscopy and probability calculations, have been determined as a function of the overall tacticity for one series of samples prepared by bulk polymerization at temperatures varying from −50 °C to 70 °C, and one series of samples prepared by polarity‐based fractionation of a commercial polymer. Using this approach, the stereochemical composition of the samples could be identified. The results are of interest to understand the changes in the physical properties as shown in earlier and current work for both series of polymers.© 2003 Society of Chemical Industry
Characteristics of polyimide ultrafine fibers prepared through electrospinning
Authors: Nah Changwoon , Han Sang Hyub , Lee Myong‐Hoon , Kim Jong Sang , Lee Dai Soo 
Published: February 2003

AbstractA novel route for making polyimide sub‐micron fibers is described. The ultrafine fibers are prepared by electrospinning a poly(amic acid) solution, a precursor of polyimide, followed by thermal imidization. The fiber diameters, which are much smaller than conventionally spun fibers, range from a few tens of nanometers to several micrometers. A rectangular cross‐section is observed in the case of sub‐micron fibers with a cross‐sectional dimension below ∼500 nm.© 2003 Society of Chemical Industry
Thermal doping of polyaniline by sulfonic acids
Authors: Poussin Denis , Morgan Huda , Foot Peter J S 
Published: February 2003

AbstractThe thermal doping of the emeraldine base (EB) form of polyaniline using two different sulfonic acids, dodecylbenzene sulfonic acid (DBSA) and p‐toluenesulfonic acid (pTSA) has been studied. Differential scanning calorimetry was used to record thermal events associated with the doping process. EB undergoes thermally induced doping with both acids at temperatures depending on the initial quantity of the dopant present. The doping temperatures show an increasing trend with increasing proportion of acid. The enthalpy of doping is also composition dependent. Conductivity values determined by the four‐probe method are given for each sample. The highest conductivities were attained at a mole ratio of 1 (dopant:EB) for both EB(DBSA) and EB(pTSA).© 2003 Society of Chemical Industry
Biodegradations of statistical copolymers composed of D,L‐lactide and cyclic carbonates
Authors: Tsutsumi Chikara , Nakagawa Katsuhiko , Shirahama Hiroyuki , Yasuda Hajime 
Published: February 2003

AbstractSyntheses and biodegradation of statistical copolymers of D,L‐lactide (D,L‐LA) with trimethylene carbonate (TMC), rac‐1‐methyltrimethylene carbonate (1‐MTMC) and 2,2‐dimethyltrimethylene carbonate (2,2‐DTMC) were investigated at various monomer ratios using SmMe(C5Me5)2THF as an initiator at 80 °C for 24 h in toluene. Biodegradations of poly(D,L‐LA‐co‐racemo‐1‐MTMC) (95/5) and poly(D,L‐LA‐co‐2,2‐DTMC) (98/2) with a compost at 60 °C proceed rapidly. Enzymatic degradations of these polymers were also performed using cholesterol esterase, lipoprotein lipase and proteinase K. Only poly(D,L‐LA‐co‐TMC) was biodegraded with cholesterol esterase, while poly(TMC), poly(1‐MTMC), poly(2,2‐DTMC) and poly(D,L‐LA) were barely degraded with these enzymes. Biodegradations of poly(D,L‐LA‐co‐TMC) (87/13) and poly(D,L‐LA‐co‐racemo‐1‐MTMC) (95/5) are rapid using proteinase K. Physical properties of these copolymers were also described.© 2003 Society of Chemical Industry
Film formation from concentrated reactive silicone emulsion: 3. film structuring
Authors: Guigner Delphine , Fischer Christian , Holl Yves 
Published: February 2003

AbstractFilm formation mechanisms from concentrated emulsions of reactive polydimethylsiloxane in water, stabilized by a polyethoxylated fatty alcohol, were studied. Following Part 1 in this series, devoted to drying mechanisms, and Part 2, to surfactant distribution, this part deals with film structuring. Three layers were observed in the thickness: a top transparent, elastic skin, made of coalesced drops; an intermediate white, non cohesive layer; and a white, cohesive layer in contact with the substrate, containing separate surfactant domains as a dispersed phase. Structuring essentially depends on the local rate of water elimination, which is itself directly connected to the global drying rate. The total amount of surfactant in the emulsion seems also to play a specific role.© 2003 Society of Chemical Industry