bluuebunny/crossref_metadata_2025_split huggingface dataset:
Affinity of human thrombin for insoluble polystyrene substituted with sulfonate, n‐hydroxyethylsulfamoyl and n‐substituted amidine functions
Authors: Khamlichi S. , Yu X. J. , Muller D. , Jozefonvicz J. , Roeland S. , Fuks R. 
Published: March 2011

AbstractA new polymeric material was prepared from polystyrene beads with N‐substituted amidines and rendered hydrophilic with sulfonate and N‐hydroxyethylsulfamoyl groups. It was synthesized by reacting the p‐chlorosulfonyl polystyrene with ethanolamine followed by the Michael‐like addition of the terminal OH of the polymer (PSEa) to N‐t‐butyl‐N'‐phenylpropenamidine 1 thus leading to the final polymer PSEaAm. Its affinity constant for human α‐thrombin calculated from the Langmuir adsorption isotherms was about 106 M−1, a value comparable to the one estimated for polystyrene modified with L‐arginine methyl ester. This new material was used as stationary phase in affinity chromatography of thrombin confirming a strong and specific interaction between the positively charged amidinium groups and the enzyme at pH = 7.4 and desorption at pH = 10 and high ionic strength.
Modification of polyetherurethane for endothelial cell seeding
Authors: Klee D. , Breuers W. , Höcker H. , Mittermayer C. 
Published: March 2011

AbstractUntil now no synthetic polymer surface was available suitable for cardiovascular implantation which effectively prevents microthrombosis for a long time. The presented concept of our work is to develop a polymer surface to promote the growth of a durable endothelial cell monolayer which would be formed on the prothesis prior to implantation. A microporous polyetherurethane foil is being used as carrier polymer for the cell monolayer. Suitable functional groups are grafted on the polymer surface by plasma polymerization. The success of the first modification steps is followed by ESCA‐analysis and scanning electron microscopy. The modified carrier polymer is the starting material for covalent binding of biopolymers which react as adhesion supporter between the synthetic polymer surface and the endothelial cells.
Artificial ovum pick‐up chamber
Authors: Hinterhofer O. , Seycek O. , Soboll R. , Zech H. , Urmann S. 
Published: March 2011

AbstractAn artificial implantable ovum pick‐up and transfer chamber was developed for a treatment of patients suffering from infertility caused by tubal defects. The first chamber prototypes were made of Cardiomat 610 polyetherurethane using a dipping technique. Two‐part hollow positive wax models were dipped into the PU‐solution in a tetrahydrofuran /dioxane mixture and dried under a complex rotation simultaneously on two axes in a laminar air flow. Special examinations were made in regard to the form of the chamber and to the reliable function of the chamber perforation. The chamber prototypes have been implanted into sheep, clinical tests are scheduled.
Polydepsipeptides: Ring‐opening polymerization of 3‐Methyl‐2, 5‐Morpholinedione, 3,6‐Dimethyl‐2,5‐morpholinedione and copolymerization thereof with D, L‐Lactide
Authors: Samyn Celest , van Beylen Marcel 
Published: March 2011

AbstractPoly (ester‐amide)s were synthesized by ring‐opening polymerization of 2,5‐morpholinedione derivatives. The monomers: 3‐methyl‐ and 3,6‐dimethyl‐2,5‐morpholinedione were prepared first, and subsequently polymerized with tin(II) bis(2‐ethylhexanoate) as an initiator at 145°C in bulk. Copolymerizations with D, L‐lactide were also investigated; in this way copolymers with higher molecular weight were obtained, which provide materials with a wider range of properties.
Morphology of poly(ethylene oxide)‐based hydrogels in relation to controlled drug delivery
Authors: Graham N. B. , Mcneill M. E. 
Published: March 2011

AbstractThe crystallinity, morphology and water swelling of a series of hydrogels based on poly(ethylene glycol)s (PEG), ¯n = 1610–8490 crosslinked by 1,2,6‐hexanetriol and the stoichiometric equivalence of dicyclohexylmethane‐4,4′‐diisocyanate as coreactant to form an infinite urethane‐linked network are examined. The equilibrium water uptake was found to be directly related to the ethylene oxide content irrespective of either ¯n(PEG) or the degree of crosslinking. Crystallinity affects the rate of swelling in water. Caffeine was incorporated into slices of hydrogels over a wide range of compositions and water contents by swelling with a solution of the drug. After drying then reswelling to desorb the caffeine the release profiles were drawn, and morphological factors contributing to the bolus and period of zero ‐ order release are propounded.
Evaluation op some cellulosic derivatives as carriers for different drugs
Authors: Dumitriu Severian , Popa Marcel , Beldie Cameluta 
Published: March 2011

AbstractThree cellulosic derivatives, namely xanthan, (chlorocarbonyl methyl) cellulose and N‐(4‐carboxyphenyl)carbamoyl methyl cellulose were used as support in coupling different drugs. Pilocarpine and neomycine were ionically coupled on xanthan; nalidixic acid, metronidazole and cephalosporine C were covalently coupled on (chlorocarbonyl methyl) cellulose, xanthan and N‐(4‐carboxyphenyl)carbamoyl methyl cellulose, in the latter case dicyclohexylcarbodiimide being used as activator. The influence of some factors on coupling efficiency was followed: drug/support ratio, volume of the solvent, reaction duration, activator/support ratio. The in vitro and in vivo tests proved the biological activity of the newly obtained macromolecular drugs.
Noncovalent complexes of water‐soluble polymers and organoplatinum compounds as potential time‐release antitumor agents
Authors: Howell B. A. , Walles E. W. , Rashidianfar R. 
Published: March 2011

AbstractThe complexation of appropriate organoplatinum compounds by water‐soluble polymers has the potential to provide a time‐release formulation which might afford a substantial reduction in the severity of side effects associated with use of organoplatinum antitumor agents. Both poly‐(N‐vinylpyrrolidone)(PVP) and poly(N‐vinyl‐5‐methyl‐2‐oxazolidone)(PVOM) form stable, biologically active, molecular complexes with organoplatinum compounds containing polar aromatic ligands. Platinum compounds suitable for complexation by these polymers include cis‐dichloro(4‐substituted o‐phenylenediamine)platinum(II), 4‐substitutedcatecholato(1,2‐diaminocyclohexane)platinum(II), and 4‐substitutedphthallato(1,2‐diaminocyclohexane)‐platinum(II) compounds.
Processing, structure and properties of oriented polymers
Authors: Ward Ian M 
Published: March 2011

AbstractThe fabrication techniques now available for the production of highly oriented polymers are reviewed. These techniques include tensile drawing from both melt‐spun and gel‐spun polymers, extrusion under pressure from the melt, and hydrostatic extrusion, ram extrusion and die drawing in the solid phase. In addition, lyotropic and thermotropic liquid crystalline polymers offer new routes to very stiff and strong polymers.Following the review of processing methods, an account is given of low strain mechanical behaviour and its relationship to structure, thermal properties (including thermal conductivity and thermal expansion behaviour) and barrier properties (permeability to liquids and gases and solubility).
Polymer blends: From molecular structure through morphology to controlled bulk properties
Authors: Teyssié Ph. 
Published: March 2011

AbstractIt is shown how the morphology and the bulk physico‐mechanical properties of polymer blends and alloys may be tailored, by using proper physical and processing conditions for homogeneous systems, and molecular engineering of the interfaces for heterophase ones.That approach, which has been substantiated by a physical study of the miscibility situations at molecular level, has been applied successfully to commodity and engineering polymer‐polymer blends, but also to polymer‐filler and polymer‐liquid heterophase systems.
Progress and challenge in polymer crazing and fatigue
Authors: Kausch Henning H. , Oudet Christian 
Published: March 2011

AbstractIn this review on polymer crazing and fatigue three aspects have been treated more explicitely: the molecular rearrangements preceding and provoking craze initiation, the competition between disentanglement and chain scission during lateral craze growth, and the distinct fatigue failure mechanism occurring in cyclically loaded PET and PA fibers. An overview on other aspects is given including references to work in progress.
Structural aspects of porous gels
Authors: Flodin Per 
Published: March 2011

AbstractThe mode of formation and the structure of both chemically and physically crosslinked polymer gels are discussed. For both types elastic and porous ones are compared. The chemically crosslinked gels from trimethylolpropane trimethacrylate (TRIM) are interesting because of their narrow distributions of small pores (radii 20 Å) when polymerized in toluene. The large pores (200 Å) on the other hand varied with concentration as could be expected.One of the ways to obtain porosity for physically cross‐linked gels is to cool solutions of polymers in certain solvents mixtures. Thus, polyacrylonitrile (PAN) yields porous gels when cooling solutions thereof in dimethyl‐formamide/water mixtures. By NMR, DSC, and X‐ray diffraction evidence has been obtained of ordered structures which at least partially exist even above the gel melting temperature.
Polymer conformation at the polymer melt surface
Authors: Silberberg A. 
Published: March 2011

AbstractDue to the symmetry which characterizes the surroundings of each chain segment in the amorphous melt all (but end) segments are equivalent in their embedment in space. Energetic interactions between segments are confined to segments in contact. Hence, in the presence of a surface only the segments actually in the surface layer will be affected and will have a statistical weight and Boltzmann factor different from segments in the bulk. The number of segments so involved is fixed, since the extent of the surface is controlled. The partition function is comprised of factors which depend neither upon the order of the segments in the chain nor upon the conformation of any particular chain. Only segments finding themselves in the surface contribute to the surface tension, with the largest contribution deriving from the density transition in the interface. This, at most temperatures, is confined to a lamella one segment layer, or less, thick. For polymer of high enough molecular weight end‐effects can be neglected and no allowance for the presence of ends is made here. It is then possible to reach a representation of surface tension in reduced coordinates, as shown already by Posner and Sanchez. Changes in chain conformation near the surface are calculated.
On the superposition of oscillatory and shear flows of viscoelastic liquids
Authors: Siginer D. A. 
Published: March 2011

AbstractImportant flow enhancement effects take place when the motion of a non‐Newtonian fluid is driven either by pressure gradients pulsating around a non‐zero mean or by longitudinal and transversal boundary waves superposed on Poiseuille flow. Flow enhancement in the latter case is an order of magnitude larger than in the former. A regular perturbation in terms of the amplitude of the oscillation is used and closed form formulas given for mass transport rates at the lowest significant order. In particular it is shown that a mean flow may be generated even when the pressure gradients oscillate around a zero mean or the boundary waves are superposed on a fluid at rest if the frequencies of two superposed waves are in certain ratios.
Effect of molecular weight distribution on the rheological behaviour of poly(vinylidene fluoride) (PVDF)
Authors: Carrot Christian , Guillet Jacques , May Jean‐François 
Published: March 2011

AbstractIn this study, six samples of commercial poly(vinylidene fluoride) are investigated. Dynamic and steady‐state shear flow experiments are carried out in the melt state in order to relate their rheological behaviour to their molecular weight distributions. This rheological investigation is performed through the use of some simple parameters related to the viscosity, elasticity and relaxation times. Plots of flow curves in reduced coordinates are used to confirm the above results.
Effect of shear on subsequent rheological transients in polymeric liquid crystals
Authors: Moldenaers P. , Mewis J. 
Published: March 2011

AbstractThe transient rheological behaviour of a lyotropic polymeric liquid crystal is investigated. The system consists of a 12% by weight solution of poly(γ‐benzyl‐L‐glutamate) in m‐cresol. The structural changes caused by steady state shearing and by large amplitude oscillatory flow are measured. This is done by following the linear moduli upon cessation of flow. The stress transients during a stepwise increase in shear rate are used for the same purpose. Flow always increases the subsequent moduli in the system used, but the mode and the intensity of the flow have a complex effect. The variable domain structure seems to be responsible for most of the measured behaviour. The data put specific constraints on the detailed mechanisms that can contribute to the global transient stress.
Study of heat treatment on the behaviour towards shrinkage, orientation and molecular order of stretched poly(vinyl chloride) fibres
Authors: Cousin Patrice , Michel Alain 
Published: March 2011

AbstractThe behaviour of stretched PVC fibres during thermomechanical treatments between 110–160°C has been studied. As far as shrinkage is concerned, three ranges of temperature have been characterized. Within the range 100–140°C the poly(vinyl chloride) undergoes a plastic deformation and has an elastoplastic behaviour. From 140 up to 170°C a creep phenomenon superimposes the elastic behaviour and then the polymer has a viscoplastic behaviour. As the temperature increases above 170°C there is flowing of polymer chains and the fibres break rapidly. Annealings carried out between 100 and 150°C cause the formation of ordered domains which are responsible for the formation of a temporary physical crosslinking network which hinders the shrinkage to such a temperature lower than their melting temperature.The loss of orientation of the amorphous phase is a rapid process which takes place as the temperature rises above 100°C even if the applied stress counterbalances the overall strain resulting from the potential shrinkage.
Shrinkage of blends of amorphous polymers with polymeric liquid crystals
Authors: Amendola E. , Carfagna C. , Nicodemo L. , Nobile M. R. 
Published: March 2011

AbstractIn this paper the shrinkage behaviour of bisphenol‐A‐polycarbonate (PC), polystyrene (PS), poly((ethylene terephthalate)‐co‐(p‐hydroxybenzoate)) liquid crystal polymer (LCP) is illustrated. Moreover, recoil's curves for PC/LCP and PS/LCP blends are shown. The different behaviour found for the two blends investigated is interpreted by taking into account that compatibility can occur between the two phases of the alloys. Moreover, the different physical state (liquid or solid) of the LCP phase at the recoil's temperature analyzed affects considerably its effectiveness in improving the shrinkage hosting matrix behaviour.
Influence of structure and of tensile modulus of adhesive joint on mechanical strength of metal plates bonded by various epoxy resins
Authors: Gilibert Yvon , Klein L. L. , Micel  
Published: March 2011

AbstractA double‐lap, adhesive bonded joint, has been optimized with a fixed thickness of the core, in order to maximize the breaking force, and to obtain reproducible results. The shear profile, longitudinal, corresponds in the central region of the overlapping to classical theory, but is represented empirically, near the extremities, by the transversal shear in outer adherends. This furnishes an abscissa of the shear maximum in the joint, that compares with the location expected in a previous study and indicates also the critical level of shear, at the threshold of microcrack initiation, that compares with the breaking strength of the solid adhesive, in a similar manner for three different adhesives for which we observed a certain length of sheared joint with a cohesive fracture.
Use of ionic membranes in the fractionation of water‐alcohol mixtures by the pervaporation process
Authors: François R. , Nguyen Q. T. , Néel J. 
Published: March 2011

AbstractFive membranes, constituted of ionic chains grafted onto inert matrix, were studied in pervaporation of water ‐ ethanol mixtures of different compositions. The permeability and selectivity of all five membranes showed a marked dependence on the nature of the counter‐ions. Water permeates preferentially through all the types of membrane and counter‐ions, except the protonated carboxylate membrane. For cation exchange membranes with alcaline counter‐ions, the selectivity decreases in the following sequence: K+<Na+<Li+<H+. The permeability of the sulfonate membrane follows the reversed sequence, while that of the carboxylate membrane follows the same sequence, i.e. there is no trade‐off between permeability and selectivity for the latter membrane. The anion‐exchange (quaternized amine) membrane behaved similarly to the sulfonate membrane, i.e. the permeability and the selectivity vary in opposite directions. An attempt to interpret the influence of the nature of counter‐ions on the basis of physico‐chemical properties of the ion pairs was made.
Photosensitive resists used in microlithography
Authors: Schue F. , Giral L. 
Published: March 2011

AbstractFor the electronics industry, resists are resins that can be applied to a substrate in a pattern of exposed and covered areas to leave some areas open for later etching or plating while protecting others for many types of printed circuit boards, whose lines and spaces are 40 nm or more wide, screening is sufficient to give needed resolution. But integrated circuit chips need the finer resolution afforded by photolithography, which uses light sensitive resists for imaging. The new lithographic processes that integrated‐circuit makers are looking at include those based on deep‐ultra violet (less than 300 nm), electron beam, and x‐ray irradiation. Until now, the near‐UV region has been satisfactory, such as at the 436/404, and 366 nm lines of mercury sources. Photoresists may be either positive or negative. Negative photoresists include resins, such as cyclised polybutadiene or polyisoprene, mixed with a bis(azide), which become crosslinked and in‐solubilized by exposure to ultraviolet light. UV irradiation photolyses bis‐(azides) to bis(nitrenes), which form aziridine groups with double bonds of neighboring chains. Developing exposed negative photoresists in a solvent dissolves away resin from unexposed areas. Positive resists are formulations like phenolic resins mixed with relatively large amounts of light sensitive solubility inhibitors, such as diazonaphtoquinones. On exposure to light, the solubility inhibitors rearrange to acidic compounds that can be leached out by bases. Thus, exposed areas of positive resists are the ones dissolved away on development. Alternatively, positive resists can be resins that are depolymerized by irradiation.
ESR and optical measurement on poly(3‐methylthiophene)
Authors: Kiess Helmut , Schärli Matthias , Harbeke Günther 
Published: March 2011

AbstractThe elementary excitations of poly(3‐methyl‐thiophene) in a doping range up to 7.5% have been found to be polarons as evidenced by ESR‐measurements. Above 7.5% doping Pauli susceptibility indicates metallic behaviour. In contrast, at 5% doping the optical absorption spectra show a transition from the three peak structure due to polarons to one with two peaks and commonly assigned to the formation of bipolarons. It is argued that a widening of the polaron levels gives rise to this phenomenon and not the induction of bipolarons. Above 20% doping the formation of a new phase of the material is observed, which is characterized by the disappearance of the peak at 1.6 eV and a well defined isosbestic point at 1.4 eV.
Charge carriers in P ‐ doped polyacetylene, optical study
Authors: Galtier M. , Montaner A. , Lakhliai Z. , Es Sbai A. 
Published: March 2011

AbstractThe dielectric properties of p‐doped polyacetylene are investigated in the infrared and far infrared region. The behaviour of the dielectric function is discussed on the basis of two kinds of carriers: free and pinned carriers. A metallic state is characterized for doping level higher than 0.03 charge per C‐H unit. The effective mass of carriers is shown to be close to the free electron mass.
Organosilicon polymers for lithographic applications
Authors: Hatzakis Michael 
Published: March 2011

AbstractOrganosilicon polymers have found many uses in the electronics industry in the last twenty‐five years due to their low dielectric constant and water‐repelling properties. These uses include insulators and encapsulating materials for electronic parts. More recently, siloxanes are being incorporated into polyimides for the purpose of increasing the water resistance, improving mechanical properties and preventing atomic oxygen attack of polyimides. Only in the last few years, some uses of organosilicon polymers in lithography have been reported. In this paper, a review of these uses will be presented and the requirements for organosilicon materials in lithography applications will be outlined.
An original method for producing polymer micro‐circuits by laser irradiation
Authors: Decker Christian 
Published: March 2011

AbstractA new method has been developed to transform PVC into carbon by means of an intense laser irradiation and thus produce high resolution conducting images. It consists of a 3‐step process: PVC was first chlorinated by UV irradiation in the presence of chlorine; the resulting polymer was then photodegraded in nitrogen to generate chlorinated polyene sequences; it was finally exposed to an argon ion laser beam (488 nm) in order to achieve the complete removal of chlorine and hydrogen atoms from the polymer backbone. The insoluble carbon material obtained contains no chlorine anymore and proved able to carry electrons. By focusing the laser beam down into the micronic range, complex conductive patterns were directly written onto the photosensitive plate at high speed.
Degradation, under corona charging, of thermoplastics used in holographic optical commutation and stabilization
Authors: Servens C. , Filliatre C. , Daviaud R. , Moisan J. Y. 
Published: March 2011

AbstractThe study of the ageing Kinetics under corona discharge of rosin esters used in holographic optical communication devices has shown that free radical inhibitors improve the stability of these matérials. Therefore, new autostabilized thermoplastic products have been synthesized by grafting antioxydant on rosin acids. The stability of materials prepared from these new thermoplastics has proved greatly enhanced.
Synthesis and mesomorphic structures of comb liquid‐crystalline polymers with lipopeptidic side chains
Authors: Gallot Bernard , Douy André 
Published: March 2011

AbstractLipopeptidic macromonomers were synthesized from bi‐functional lipids by two methods and transformed into comb copolymers with lipopeptidic side chains by radical polymerization of their acrylate, methacrylate, acrylamide or methacrylamide terminal group. X‐ray diffraction and differential scanning calorimetry studies showed that comb copolymers exhibit both a thermotropic and a lyotropic behaviour and present smectic and nematic mesophases. The influence of the solvent concentration, the degree of polymerization of the peptidic chains and the nature of the main chains on the structural parameters of the smectic mesophases were established in the case of copolymers with liposarcosine side chains.