bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of feeding micronised flaxseed on yield and composition of milk from Holstein cows
Authors: Mustafa AF , Chouinard PY , Christensen DA
Published: July 2003

Nine multiparous Holstein cows were used in three 3 × 3 Latin squares to investigate the effects of feeding unheated and micronised flaxseed on milk yield and milk fatty acid composition. Three diets were formulated to meet the nutrient requirement of dairy cows in early lactation: a control diet with no added flaxseed (NFS), an unheated flaxseed diet (UFS) and a micronised flaxseed diet (MFS). The level of flaxseed in UFS and MFS was 70 g kg−1 of the diet dry matter (DM). Feeding flaxseed to dairy cows had no effect on DM intake or milk yield. However, energy‐corrected milk was higher (P < 0.05) for cows fed MFS than for those fed UFS or NFS. Supplemental flaxseed reduced (P < 0.05) the milk fat percentage without affecting the concentration of milk protein or milk lactose. However, the yield of milk components was not affected by feeding flaxseed. The concentrations of short‐chain (C4:0 to C12:0) and medium‐chain (C14:0 to C17:0) fatty acids were decreased (P < 0.05) while those of long‐chain fatty acids (C18:0 to C18:3) were increased (P < 0.05) in the milk of cows fed UFS and MFS compared with cows fed NSF. Feeding flaxseed to dairy cows can alter the milk fatty acid composition, but only minor effects on milk fatty acid composition can be expected by feeding micronised versus unheated flaxseed. Copyright © 2003 Society of Chemical Industry
Nutrient utilisation and performance of broilers in response to processed flaxseed dietary levels and vitamin B6 supplementation
Authors: Shen Yingran , Chavez Eduardo R
Published: July 2003

The objective of this study was to determine the effects of processing and dietary inclusion level of flaxseed on broiler performance and nutrient utilisation. Flaxseed was included in the diet fed to day‐old broilers for the first 3 weeks as whole seed, ground seed, autoclaved whole seed, ground autoclaved whole seed or whole seed pelleted with the other ingredients, at levels of 0, 100, 120 and 140 g kg−1. Chicks fed the pelleted flaxseed‐containing diets had heavier body weights, consumed more feed and had better feed/gain ratios than those fed the other flaxseed‐containing diets during the 3 weeks period (P < 0.01). The flaxseed level in the diet also had very significant (P < 0.01) effects on body weight and feed/gain ratio at the end of weeks 1 and 3, with the diets containing 100 g kg−1 flaxseed resulting in better performance than the other flaxseed‐containing diets. Among the flaxseed containing diets, the pelleted diets led to higher apparent ether extract digestibilities, with values of 778 and 770 g kg−1 for the diets containing 100 and 140 g kg−1 flaxseed respectively. This better utilisation of ether extract by young broilers may explain the significantly (P < 0.05) higher AMEn (apparent metabolisable energy) value of 2924 kcal kg−1 for the pelleted 140 g kg−1 flaxseed‐containing diet. This was 15.4–17.5% higher than for the diets with the same level of flaxseed but provided as raw or autoclaved whole seed. The pelleting of flaxseed allowed an inclusion rate of 100 g kg−1 without any reduction in the performance and nutrient utilisation of broilers. Copyright © 2003 Society of Chemical Industry
Evaluation of heat and oxidative damage during storage of processed tomato products. II. Study of oxidative damage indices
Authors: Lavelli Vera , Giovanelli Gabriella
Published: July 2003

Tomato products (pulp, puree and paste) submitted to accelerated aging (30, 40 and 50 °C for 3 months) were studied to evaluate variations in the kinetics of the degradation of antioxidants and antioxidant activity. The carotenoids lycopene and β‐carotene, ascorbic acid, rutin and total phenolics were analysed. The antioxidant activity was measured using (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radicals and hydrogen peroxide, and (b) the linoleic acid/CuSO4 system, which promotes lipid peroxidation. The ascorbic acid content decreased even at 30 °C, following pseudo‐first‐order kinetics, with an activation energy of 105 200 J mol−1 for tomato pulp and 23 600 J mol−1 for tomato paste. The lower the initial ascorbic acid content, the higher was the degradation rate. Variations in phenolic compounds occurred at 40 °C and higher, following pseudo‐zero order kinetics. The antioxidant activity of the hydrophilic fraction of the tomato products depended on both antioxidant degradation and the Maillard reaction and could not be described by a kinetic model. The β‐carotene content decreased even at 30 °C, whereas the lycopene content was stable in all samples. The antioxidant activity of the lipophilic fraction of the tomato products decreased following pseudo‐first order kinetics, with an activation energy of 22 200 J mol−1 for tomato pulp and 20 200 J mol−1 for tomato paste. It is concluded that significant ‘oxidative damage’ can occur in tomato products during their commercial shelf‐life. Copyright © 2003 Society of Chemical Industry
Simplified process for the production of sesame protein concentrate. Differential scanning calorimetry and nutritional, physicochemical and functional properties
Authors: Escamilla‐Silva Eleazar M , Guzmán‐Maldonado Salvador H , Cano‐Medinal Alicia , González‐Alatorre Guillermo
Published: July 2003

The effects of a simplified production process on the yield, protein content and differential scanning calorimetric analysis of a sesame protein concentrate were studied. The results were compared with those for similar products obtained by the traditional method. The protein content of the (spray‐dried) sesame concentrate obtained by the simplified process (549 g kg−1) was similar to that of the concentrates obtained by the traditional method (515–565 g kg−1). Spray‐dried samples showed higher Td and Tm and lower ΔH than freeze‐dried samples. In addition, the chemical composition, nutritional quality and physicochemical and functional characteristics of the sesame protein concentrate obtained by the simplified process were compared with those of a similar soybean product. The protein, lysine and calcium contents of the sesame concentrate were lower than those of the soybean concentrate, but the digestibility of the protein was the same for both products. The phytic acid content of the sesame concentrate diminished significantly, but was still higher than that of the soybean concentrate. The water absorption and protein solubility were higher for the soybean concentrate, whereas the oil absorption and viscosity at pH 3 were higher for the sesame concentrate. Copyright © 2003 Society of Chemical Industry
Effect of grain pre‐treatment on different extractable phenolic groups in cereals and legumes commonly consumed in Tanzania
Authors: Towo Elifatio E , Svanberg Ulf , Ndossi Godwin D
Published: July 2003

Extractable phenolic compounds, classified as total phenolics, resorcinols, catechols and galloyls, were determined in cereals and legume food grains commonly consumed in Tanzania, using various colorimetric methods. Grain samples of red sorghum (udo), finger millet, cowpea, mung bean and brown kidney bean were further processed—soaked in water at different pHs, germinated, cooked or dehulled (legumes only)—and the effect on extractable phenolics was analysed. In untreated grains, total phenolics ranged from 0.9 to 33.7, catechols from 0.8 to 13.5 and resorcinols from 0.2 to 11 mg catechin equivalents (CE) g−1. Galloyls (tannic acid equivalents, TAE) were found in negligible amounts in most grains, but in appreciable amounts in red sorghum (5.5 mg g−1). Processing of grains led to variable effects on the extractable phenolics. Soaking the grains significantly (p < 0.05) reduced the amount of total extractable phenolics in red sorghum, finger millet and cowpea, with alkali and acidic media being more effective. Water soaking had no effect on total extractable phenolics in mung bean and water, while alkali and acidic soaking had no effect on total extractable phenolics in brown kidney bean. Extractable catechols and resorcinols were affected by soaking in a similar pattern to total extractable phenolics. Germination reduced total extractable phenolics, catechols and resorcinols in all samples, except for catechols in mung bean. Cooking (boiling of grains) was more effective in reducing total extractable phenolics in cereals than germination and water soaking, while dehulling was the most effective method for reducing total extractable phenolics in legumes (p < 0.01). Copyright © 2003 Society of Chemical Industry
Translations from natural deduction to sequent calculus
Authors: von Plato Jan
Published: July 2003

Gentzen's “Untersuchungen” [1] gave a translation from natural deduction to sequent calculus with the property that normal derivations may translate into derivations with cuts. Prawitz in [8] gave a translation that instead produced cut‐free derivations. It is shown that by writing all elimination rules in the manner of disjunction elimination, with an arbitrary consequence, an isomorphic translation between normal derivations and cut‐free derivations is achieved. The standard elimination rules do not permit a full normal form, which explains the cuts in Gentzen's translation. Likewise, it is shown that Prawitz' translation contains an implicit process of cut elimination.
Choice principles for special subsets of the real line
Authors: Keremedis Kyriakos , Tachtsis Eleftherios
Published: July 2003

We study the role the axiom of choice plays in the existence of some special subsets of ℝ and its power set ℘(ℝ).
Metric spaces and the axiom of choice
Authors: De la Cruz Omar , Hall Eric , Howard Paul , Keremedis Kyriakos , Rubin Jean E.
Published: July 2003

We study conditions for a topological space to be metrizable, properties of metrizable spaces, and the role the axiom of choice plays in these matters.
Sequent systems for compact bilinear logic
Authors: Buszkowski Wojciech
Published: July 2003

Compact Bilinear Logic (CBL), introduced by Lambek [14], arises from the multiplicative fragment of Noncommutative Linear Logic of Abrusci [1] (also called Bilinear Logic in [13]) by identifying times with par and 0 with 1. In this paper, we present two sequent systems for CBL and prove the cut‐elimination theorem for them. We also discuss a connection between cut‐elimination for CBL and the Switching Lemma from [14].
Some remarks on indiscernible sequences
Authors: Casanovas Enrique
Published: July 2003

We prove a property of generic homogeneity of tuples starting an infinite indiscernible sequence in a simple theory and we use it to give a shorter proof of the Independence Theorem for Lascar strong types. We also characterize the relation of starting an infinite indiscernible sequence in terms of coheirs.
Some results on Kripke models over an arbitrary fixed frame
Authors: Bagheri Seyed Mohammad , Moniri Morteza
Published: July 2003

We study the relations of being substructure and elementary substructure between Kripke models of intuitionistic predicate logic with the same arbitrary frame. We prove analogues of Tarski's test and Löwenheim‐Skolem's theorems as determined by our definitions. The relations between corresponding worlds of two Kripke models 𝒦 ⪯ 𝒦′ are studied.
Computable choice functions for computable linear orderings
Authors: Lerman Manuel , Watnick Richard
Published: July 2003

A choice set for a computable linear ordering is a set which contains one element from each maximal block of the ordering. We obtain a partial characterization of the computable linear order‐types for which each computable model has a computable choice set, and a full characterization in the relativized case; Every model of the linear order‐type α of degree ≤ d has a choice set of degree ≤ d iff α can written as a finite sum of order‐types, each of which either has finitely many blocks, or has order‐type n · η for some integer n.
On the regular extension axiom and its variants
Authors: Rathjen Michael , Lubarsky Robert S.
Published: July 2003

The regular extension axiom, REA, was first considered by Peter Aczel in the context of Constructive Zermelo‐Fraenkel Set Theory as an axiom that ensures the existence of many inductively defined sets. REA has several natural variants. In this note we gather together metamathematical results about these variants from the point of view of both classical and constructive set theory.
A note on dual‐intuitionistic logic
Authors: Kamide Norihiro
Published: July 2003

Dual‐intuitionistic logics are logics proposed by Czermak (1977), Goodman (1981) and Urbas (1996). It is shown in this paper that there is a correspondence between Goodman's dual‐intuitionistic logic and Nelson's constructive logic N−.
New sequent calculi for Visser's Formal Propositional Logic
Authors: Ishii Katsumasa
Published: July 2003

Two cut‐free sequent calculi which are conservative extensions of Visser's Formal Propositional Logic (FPL) are introduced. These satisfy a kind of subformula property and by this property the interpolation theorem for FPL are proved. These are analogies to Aghaei‐Ardeshir's calculi for Visser's Basic Propositional Logic.
Pf ≠ NPf for almost all f
Authors: Hamkins Joel David , Welch Philip D.
Published: July 2003

We discuss the question of Ralf‐Dieter Schindler whether for infinite time Turing machines Pf = NPf can be true for any function f from the reals into ω1. We show that “almost everywhere” the answer is negative.
Developments in understanding the formation, structure and properties of polymer networks
Authors: Stepto R.F.T. , Cail J.I. , Taylor D.J.R. , Ward I.M. , Jones R.A.
Published: July 2003

Two areas of networks modelling are described. The first is concerned with the application of a Monte‐Carlo (MC) algorithm to account fully for loop formation in RA2 + R′B3 and RA2 + R′B4 polymerisations. The resulting interpretation of experimental elastic moduli of HDI‐based polyurethane (PU) networks prepared at different dilutions shows it is essential to account for elastic losses in loop structures of all sizes. An important parameter, x, is introduced, namely the average fractional loss of elasticity per larger loop structure relative to the loss per smallest loop structure. Application of the MC calculations to the formation and resulting structures of MDI‐based PU networks and poly(dimethyl siloxane) (PDMS) networks shows the competing effects of loop structures and chain interactions (PU) or topological entanglements (PDMS) on the modulus. The second area of networks modelling is the MC simulation of the elastic behaviour of chains in networks using realistic rotational‐isomeric‐state chain models. Stress‐strain and stress‐optical properties can be modelled quantitatively. In stress‐strain behaviour, an increase in the proportion of fully extended chains with increasing macroscopic strain causes a reduction in network modulus at moderate macroscopic strains. There is no need to invoke a transition from affine to phantom chain behaviour as deformation increases. For stress‐optical properties, the MC method gives, in agreement with experiment, values of stress‐optical coefficient that are dependent upon both deformation ratio and network‐chain length. Applications of the method to the quantitative modelling of the stress‐strain properties of PDMS networks and the stress‐optical properties of polyethylene and poly(ethylene terephalate) networks are described.
OCTA (Open Computational Tool for Advanced material technology)
Authors: Doi Masao
Published: July 2003

OCTA (Open Computational Tool for Advanced material technology) is an integrated simulation system for polymeric materials developed by a joint project of industry and academia supported by Japanese government. It aims at exploring the utility of mesoscale modelings developed in polymer science. OCTA consists of four simulation engines (molecular dynamics engine, rheology engine, interface engine, multi‐phase engine) and a simulation platform. The system is designed to be open and extendable: all programs and source codes can be downloaded at http://octa.jp.
Supramolecular research by single molecule force spectroscopy
Authors: Cui Shuxun , Zhang Wenke , Xu Qiaobing , Wang Chi , Zhang Xi
Published: July 2003

Single molecule force spectroscopy (SMFS) is a new kind of technique based on atomic force microscope, which allows detecting force as low as pico‐newtons directly. Herein based on our recent work, we want to demonstrate the investigation of supramolecular structures and interactions in polymer systems by SMFS, such as desorption force between polymer and substrate, identifiability of polymer micelle and its interaction with surfactant, splitting force of ion‐induced helical structure in polysaccharide. It shows well that SMFS is a powerful tool in the study of supramolecular science.
Preparation of multihollow polymer particles by the alkali/cooling method under partial neutralization conditionsa)
Authors: Okubo Masayoshi , Okada Masahiro , Shiba Kenjin
Published: July 2003

Heterogeneity in the formation of multihollow structure among submicron‐sized styrene‐methacrylic acid copolymer particles, which were produced by batch emulsion copolymerization, by the alkali/cooling method under partial neutralization of carboxyl groups was investigated. There was a threshold of the acid content to form the multihollow structure. The heterogeneity among the particles was based on the heterogeneity of the acid content among the original particles.
A study on hydrogen bonding in controlled‐structure benzoxazine model oligomers
Authors: Kim Ho‐Dong , Ishida Hatsuo
Published: July 2003

The synthesis procedure for controlled‐structure benzoxazine model oligomers is described. To understand the complex hydrogen bonding structure, a series of benzoxazine model oligomers is characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT‐IR). The NMR resonances for model oligomers are newly assigned. The FT‐IR spectra for model benzoxazine oligomers are carefully investigated both in crystalline and solution states. The distribution of hydrogen bonding species in benzoxazine model oligomers is quantitatively analyzed using FT‐IR spectra. The cyclic conformations for the oligomers are also proposed.
Polymer industry and innovation in macromolecule science and technology in china
Authors: Dingyi Hong
Published: July 2003

The paper describes the recent technological progress in synthetic resin, synthetic fiber and synthetic rubber in China, as well as the achievements obtained in process technology development, catalyst R&D, the adjustment of product slate, and product capacity and output. Also, in the paper, an expectation image of next decade has been drawn.
Nanometer scale mechanical study on well defined nanostructured chain aggregation of polyethylene
Authors: Du Binyang , Liu Jieping , Zhang Jian , Yang Decai , He Tianbai , Tsui Ophelia K.C.
Published: July 2003

Two kinds of polyethylene chain aggregation with chain axis perpendicular and parallel to the supported substrate were designed and successfully obtained from melt under an electric field and by melt‐drawn method, respectively. Their nanostructures were investigated by using transmission electron microscopy and atomic force microscopy. The chain modulus of the aggregations along and perpendicular to the chain axis were quantitatively measured to be 267 GPa and 13.8 GPa, respectively, by performing atomic force microscopy combining nanoindentation technique. This work provides new method to study polymer properties on the nanometer or molecular scale and insight into structure‐property relationship on the nanometer scale for polymers, which was usually established based on micro‐scale structure and macro‐scale property.
Progress in liquid chromatography of synthetic electroneutral polymers
Authors: Berek Dušan
Published: July 2003

Recent achievements and anticipated future progress in high performance liquid chromatography of synthetic electroneutral polymers (polymer HPLC) are briefly reviewed. Basic retention mechanisms of polymer HPLC are explained and corresponding separation procedures are discussed. Advantages, drawbacks and pitfalls are presented of the most important polymer HPLC method, namely size exclusion chromatography. Principles of polymer HPLC methods combining various separation mechanisms within one chromatographic column (coupled procedures) or in a set of different chromatographic columns (two‐ and multi‐dimensional procedures) are outlined.
Macromolecular assembly: from irregular aggregates to regular nanostructures
Authors: Jiang Ming , Duan Hongwei , Chen Daoyong
Published: July 2003

Based on our long‐term research on interpolymer complexation due to hydrogen bonding, we proposed several novel self‐assembly approaches to polymeric micelles with regular structures. Differing from micelles of block and graft copolymers, our micelles don't have any chemical bonds between the core and shell. In addition, some of these approaches have been proved to be effective to fabricate hollow aggregates.
Structure and dynamics of dendritic macromolecules
Authors: Ozerin Alexander N. , Muzafarov Aziz M. , Gordeliy Valentin I. , Kuklin Alexander I. , Ignat'eva Galina M. , Krykin Mikhail A. , Ozerina Lyudmila A. , Shumilkina Natalia A. , Islamov Akhmed Kh. , Sharipov Eugene Yu. , Mukhamedzyanov Ruslan I.
Published: July 2003

The highly branched regular organosilicon polymer structures (dendrimers) were examined. A number of experimental techniques were used to study the structure and dynamics of dendritic macromolecules in a bulk state as well as in diluted solutions. The reliable quantitative structural and dynamical characteristics, which were obtained within a framework of a complex investigation, arranged a background to resolve several of the contradictions in accounting for the results coming from the various experimental methods and numerical calculations. The explanations were found for: (a) why dendrimers look as penetrable and impenetrable with the solvent at the same time; (b) why dendrimers reveal typical for the linear polymers segmental relaxation spectra and possess a translation diffusion of the whole macromolecule in addition. The small‐angle neutron scattering experiments on the dendrimers with the specially labeled terminal groups showed that the terminal groups are concentrated near the periphery of the dendrimer structure.
Synthesis and optical properties of hyperbranched polyarylenes and linear polyacetylenes
Authors: Xie Zhiliang , Peng Han , Lam Jacky W.Y. , Chen Jumwu , Zheng Yonghua , Qiu Chengfeng , Kwok Hoi Sing , Tang Ben Zhong
Published: July 2003

New hyperbranched polyarylenes (HPAs) and linear polyacetylenes (LPAs) containing chromophoric moieties were synthesized in high yields (up to 97%) by coablt‐ and tantalum‐catalyzed polycyclotrimerizations and tungsten‐catalyzed metathesis polymerizations, respectively. The polymers possessed high molecular weights (Mw up to 113 000 Da) and were completely soluble in common organic solvents. The HPAs emitted strong UV light of 400 nm in high quantum yields (ΦF up to 0.98) and limited intense laser pulses, whose limiting threshold and signal suppress power were better than those of C60, a well‐known optical limiter. The electroluminescence (EL) devices of the LPAs emitted blue light of ∼460 nm and exhibited maximun brightness, current efficiency, and external quantum efficiency of 1118 cd/m2, 1.53 cd/A, and 0.85%, respectively.
Polymer dynamics of thin films and monolayers
Authors: Yu Hyuk
Published: July 2003

Surface viscoelasticity of polymeric thin films and monolayers at the air/water interface can be deduced from the propagation characteristics of spontaneously generated capillary waves. The characteristics are probed by the technique of surface light scattering. It is shown that vinyl polymers with hydrophilic pendant groups and polyethers give rise to the predominantly elastic monolayers and thin films whereas those with relatively hydrophobic pendant groups the more viscous monolayers and thin films.
New trends in industrial polymer research
Authors: Schenck Hans Uwe
Published: July 2003

In the past decades a shift in paradigm took place in industrial polymer research. Only a few new polymers were developed based on new monomeric building blocks. The main focus is now on tailoring “new polymers” with well‐defined structure and properties based on a set of low cost “old” monomers using controlled polymerization mechanisms.
Self‐assembly in mixtures of block copolymers: “co‐surfactant effects” on morphology control
Authors: Hashimoto Takeji , Yamaguchi Daisuke , Court François
Published: July 2003

We found that competing long‐range interactions of the two block chains in their binary mixtures give intriguing effects on ordered microdomain structures. One effect is a co‐surfactant effect observed when the two blocks are mixed with their junctions on common interfaces, giving rise to such effects as (i) the two lamella‐forming block copolymers give hexagonal cylinders and consequently to the increase of the interface curvatures, or (ii) a short symmetric block copolymer mixed with a large asymmetric block copolymer effectively decreases the interface curvatures, depending upon composition and molecular weight of the short block copolymer. The other effect is the one which causes two blocks macroscopically phase‐separate into different ordered domains.
Photochemically‐induced refractive index and fluoresence patterning on polymer films
Authors: Horie Kazuyuki , Murase Seiichiro , Takahashi Satoshi , Teramoto Madoka , Furukawa Hidemitsu
Published: July 2003

The molecular design for large photo‐induced refractive index changes in transparent visible light region was proposed and realized with norbornadiene polymers and poly(vinyl cinnamate). The patterning of pure refractive‐index contract on their transparent films was made with near‐field scanning optical microscopy (NSOM). Reversible fluorescence patterning on polymer films is also presented by using controlled energy transfer from a fluorescent pyromethene to a photochromic diarylethene.
Surface friction of polyelectrolyte gels
Authors: Gong Jian Ping , Kagata Go , Osada Yoshihito
Published: July 2003

The friction between two chemically cross‐linked polyelectrolyte gels carrying the same sign of charges has been investigated in pure water as well as in salt solutions using a rheometer. It is found that the friction was largely dependent on the charge densities of the gel surface and the ionic strength of the aqueous solution. The chemical structures of the polyelectrolyte gels also play an important role. The friction is described in terms of the hydrodynamic lubrication of the solvent layer between the two gel surfaces, which is formed due to the electrostatic repulsion of the two gel surfaces. The thickness of the solvent layer has been estimated using the Poisson‐Boltzmann equation supposing that the ionic osmotic pressure is balanced by the normal pressure applied on the gel. The friction values have been calculated by considering the shear flow of solvent in gel region using the Debye‐Binkman equation. For strongly charged polyelectrolyte gels swollen in pure water, the theoretical analysis shows that the friction coefficient almost has no dependence on the water content of the gel, which well agrees with the experimental observations.
Highly conducting graphitic carbon films and nano patterns from poly(p‐phenylenevinylene) prepared on the surface of silicon wafers by the CVD method
Authors: Kim Kyungkon , Zhong Guolun , Jin Jung‐Il
Published: July 2003

We could prepare highly electrically conducting graphitic carbon films and nano patterns by carbonizing the poly(p‐phenylenevinylene) (PPV) films and nano patterns prepared on the silicon surface by the chemical vapor deposition polymerization method of α,α'‐dichloro‐p‐xylene. When the PPV films on silicon wafers were thermally treated at 850°C highly oriented graphitic carbon films were obtained which exhibit an electrical conductivity higher than 0.7 x 103 Scm−1. This conductivity value is more than 10 times the value for the carbon films obtained from bulk PPV films or glassy carbons heat treated at the same temperature. Moreover, nano patterns of graphitic carbons were easily obtained on silicon wafers through carbonization of nano patterned PPV obtained by the CVD polymerization method.
Excimer suppression mechanism in light emitting polymer blends
Authors: Yu J.‐W. , Kim J.K. , Kim D.Y. , Kim C.H. , Song N.W. , Kim D. , Kim C.Y.
Published: July 2003

Alternating copolymer of distyrylenediethylhexyloxyphenylene and phenyltriazine(PPVT) or hydroxyphenyltriazine(PVOT) is synthesized in order to enhance the electron mobility in the light emitting polymers. Photoluminescence(PL) spectrum of PPVT shows excimeric characteristics but PVOT generates excitonic PL emission. A blend of PVOT with polyvinylcarbazole(PVK) enhances the PL intensity of PVOT on photoexcitation of PVK indicating an efficient energy transfer. The excimeric PL emission of PPVT is suppressed on photoexcitation of a blend with PVK at the UV‐visible absorption(AB) maximum of PVK, which is an indirect photoexcitation, while the energy transfer from PVK to PPVT is not completed.
Cell sheet engineering: intelligent polymer patterned surfaces for tissue engineered liver
Authors: Harimoto Masami , Yamato Masayuki , Kikuchi Akihiko , Okano Teruo
Published: July 2003

We describe a new culture system utilizing the temperature‐responsive polymer grafted surface for designing of cell position and layered tissue reconstruction. Organizing of the hepatic tissue structure by controlling the culture system, that is patterned co‐culture and layered cell sheet co‐culture achieved by moving the cultured cells from the culture surface, resulted in regulation of the hepatocyte function. The technique for cell sheet manipulation would promote the liver tissue engineering in quality.
Synthesis of functional polycarbonates by lipase‐catalyzed ring‐opening polymerization
Authors: Feng Jun , Zhuo Renxi , He Feng , Wang Xuli
Published: July 2003

Poly(5‐benzyloxy‐trimethylene carbonate) (PBTMC), a new functional polycarbonate was synthesized by enzymatic ring‐opening polymerization in bulk at 150°C using Porcine pancreas lipase (PPL) or Candida rugosa lipase (CL) as catalyst. Influences of different polymerization conditions such as the source of enzyme, enzyme concentration and polymerization time on the molecular weight and yield were studied. The results showed that PPL exhibited higher activity than CL. Both higher molecular weight(Mn, 18953) and yield(98%) could be obtained by the use of PPL as catalyst. 1H NMR spectrum showed no decarboxylation occurrence during the ring‐opening polymerization.
Degradable polymers: design, synthesis and testing
Authors: Finne Anna , Ryner Maria , Albertsson Ann‐Christine
Published: July 2003

The object for our research is to mimic Nature's perfectly designed resorbable materials to obtain important materials, which are biocompatible and degradable. We have therefore synthesized different architectures and copolymers of aliphatic polyesters with ring‐opening polymerization. The first studies of these materials properties show that properties like hydrophilicity and tensile properties can be controlled.
Dextran‐spermine conjugate: an efficient vector for gene delivery
Authors: Azzam T. , Eliyahu H. , Makovitzki A. , Domb A.J.
Published: July 2003

Cationic Polysaccharides based on oligoamine‐dextran conjugates were synthesized and tested as vectors for gene transfection. Dextran with 40 kDa in average molecular weight was oxidized under mild conditions by potassium periodate to obtain the respective polyaldehydes in relatively high yields (∼90%). The oxidized dextran was reacted by reductive animation with various oligoamines of 2 to 4 amino groups to obtain the corresponding imine‐conjugates. These water‐soluble polymers were then reduced by excess of sodium borohydride to obtain the corresponding amine‐conjuagtes in 30‐40% overall yield. The electrostatic interactions of the representative polycations with plasmid DNA were evaluated as a function of charge ratio (+/−, polymer/DNA) and ionic strength of the medium applying the ethidium‐bromide quenching assay. Although most synthetic polycations formed stable complexes with Plasmid DNAs, only the dextran‐spermine conjugate of a defined amino content and molecular weight was able to transfect cells with high efficiency.
Controlling polymer structures by atom transfer radical polymerization and other controlled/living radical polymerizations
Authors: Matyjaszewski Krzysztof
Published: July 2003

Fundamentals of controlled/living radical polymerization (CRP) and Atom Transfer Radical Polymerization (ATRP), relevant to the synthesis of controlled polymer structures are described. Macromolecular brushes with star like structure are used as an example to illustrate synthetic power of ATRP.
An important biodegradable polymer – polylactone‐family polymer
Authors: Wang Shenguo , Cai Qing , Bei Jianzhong
Published: July 2003

Systemic investigation on the synthesis and properties of aliphatic polylactones were carried out. And various materials were obtained with different degradation rates and mechanical properties. Two in vivo experiments were presented in this study to envision the biomedical applications of this kind of aliphatic polylactones.
Aggregation of ionic amphiphils in dilute solutions controlled by oppositely charged polyelectolyte templates
Authors: Kasaikin Victor A. , Zakharova Julia A. , Litmanovich Ekaterina A. , Ivleva Elena M. , Zezin Alexander B. , Kabanov Victor A.
Published: July 2003

Formation and structure of water‐soluble complexes of poly(acrylic acid) (PA) and poly(diallyldimethylammonium chloride) (PDADMAC) with oppositely charged surfactants have been studied by elastic and quasi‐elastic laser light‐scattering and high‐speed sedimentation technique. It was experimentally shown that generation of intracomplex micellar phase is the necessary condition for formation of such complexes. Minimum aggregation number of the surfactant ions in the complex micelle was found to be determined by the chemical nature of the polymer.
Coordination structure of active site in synthetic hemoprotein (albumin‐heme) with dioxygen and carbon monoxide
Authors: Tsuchida Eishun , Nakagawa Akito , Komatsu Teruyuki
Published: July 2003

Recombinant human serum albumin (rHSA) incorporating the tetraphenylporphinatoiron(II) derivative with a covalently linked proximal base (FeP) [albumin‐heme (rHSA‐FeP)] is a synthetic hemoprotein, which can bind and release dioxygen (O2) reversibly under physiological conditions. The coordination structure and spin‐state of the active site in rHSA‐FeP with O2 and carbon monoxide (CO) were revealed by magnetic circular dichroism (MCD), resonance Raman (RR), and infrared (IR) spectroscopy. Under an N2 atmosphere, the MCD spectrum of rHSA‐FeP showed the formation of the five‐coordinate ferrous high‐spin complex of FeP. Upon exposure of this solution to O2 or CO, the spectral pattern immediately changed to that of a six‐coordinate ferrous low‐spin species. The vibration stretching frequencies of the coordinated O2 (νO2) and CO (νCO) were observed at 1158 cm−1 and 1964 cm−1, respectively. The electronic structures of the O2‐ and CO‐adduct complexes of FeP in the hydrophobic pocket of albumin are both identical to those for FeP itself in toluene solution.
Synthesis and properties of carbon dioxide – epoxides copolymers from rare earth metal catalyst
Authors: Quan Zhilong , Min Jiadong , Zhou Qinhai , Xie Dong , Liu Jingjiang , Wang Xianhong , Zhao Xiaojiang , Wang Fosong
Published: July 2003

Ternary rare earth metal coordinate was used to the copolymerization of epoxides and carbon dioxide. Rare earth compound is crucial in raising the catalytic activity and improving the micro‐structure of the aliphatic polycarbonates. The Tg of the aliphatic polycarbonate is adjustable by controlling the relative molar ratio of the comonomers.
Novel characterization of branching and/or cross‐linking structures in condensation polymers by reactive pyrolysis‐gas chromatography in the presence of organic alkaline
Authors: Tsuge Shin , Ohtani Hajime , Oba Keishi
Published: July 2003

The reactive pyrolysis‐gas chromatography technique was applied to verify the branching and/or cross‐linking structures in an industrially available polycarbonate (PC) sample and its thermally treated one through identification of specific pyrolysis products directly reflecting the related abnormal structures. On the pyrogram of the thermally treated sample, the peaks reflecting the abnormal structures such as branching and/or cross‐linking were observed together with those reflecting main chain and end groups. Furthermore, the fact that some of those characteristic peaks were also observed on the pyrogram of the industrially available PC sample prepared by the melt method indicated that the branching and/or cross‐linking reactions would occur to some extent in the PC synthesized by the melt method.
Recent developments in oriented polymers for biomedical and engineering applications
Authors: Ward Ian Macmillan
Published: July 2003

A review is presented of recent research at Leeds University which has been directed at devising novel methods for the production of oriented polymer structures. First, the new hot compaction process for oriented fibre and tapes is described, together with its applications to polyethylene and polypropylene where there are a number of practical developments. Secondly, there is the use of hydrostatic extrusion to make load bearing oriented products from hydroxyapatite filled polyethylenes. The production routes include the application of high pressure annealing prior to hydrostatic extrusion and the preparation of high modulus polyethylene fibre/hydroxyapatite billets as the starting point. Finally, recent progress on die‐drawing as a means to producing oriented monofilaments and biaxially oriented tubes is described, where the applications include polymer ropes, pipes for gas and water distribution and transparent cans for packaging.
Time‐resolved structural studies in fiber processing
Authors: Burger Christian , Ran Shaofeng , Fang Dufei , Cookson David , Yabuki Kazuyuki , Teramoto Yoshihiko , Cunniff Philip M. , Viccaro P. James , Hsiao Benjamin S. , Chu Benjamin
Published: July 2003

Time‐resolved and off‐line synchrotron wide‐angle and small‐angle x‐ray scattering (WAXS and SAXS) was used to study the structure formation in poly‐p‐phenylenebenzobisoxazole (PBO) fibers during various stages of spinning, coagulation, and heating processes. WAXS data could be explained in terms of liquid‐crystalline structures of varying degrees of order. A structure model is proposed that is in accordance with the observed SAXS four‐point pattern.
Extruder processing for nanoblends and nanocomposites
Authors: Hu Guo‐Hua , Feng Lian‐Fang
Published: July 2003

Structuring multiphase polymer materials to a micrometer scale (micro‐structuration) is a facile engineering practice. However, structuring them to a nanometer scale (nano‐structuration) is a formidable engineering challenge. In this paper, it is shown first why traditional extruder compounding processes only lead to micro‐structuration and then how one may use the extruder type of mixer to structure multiphase polymer materials at a nano‐meter scale to obtain nanostructured polymer blends (nanoblends) and nanostructured polymer composites (nanocomposites).
Bimodal polyethylene products from UNIPOLTM single gas phase reactor using engineered catalysts
Authors: Liu Han‐Tai , Davey Chris R. , Shirodkar Pradeep P.
Published: July 2003

Advanced catalyst engineering from Univation Technologies provides the capability to produce polyethylene with bimodal molecular weight distribution and bimodal composition distribution in a single gas phase reactor. This paper will discuss the structure‐property‐process relationship for these engineered polyethylene products. Examples of High Density Polyethylene (HOPE) polymers with bimodal molecular weight distribution will demonstrate the utility of the engineered catalysts in high molecular weight film production. Examples of Linear Low Density Polyethylene (LLDPE) polymers with broad comonomer composition distribution will demonstrate the utility of the engineered catalysts for high strength film applications. Examples of HOPE polymers with bidmoal molecular distribution and controlled comonomer distribution will demonstrate the capability of Univation's latest engineered catalysts for high performance pipe applications.
Multibranched star‐shaped polyethers
Authors: Lapienis Grzegorz , Penczek Stanislaw
Published: July 2003

Synthesis of multibranched star‐shaped polyethers having poly(ethylene oxide)s (PEO) arms is described. The novel method of preparing these multibranched macromolecules consists in reaction of the ‐OH ended oligomers with dicyclic compounds; e.g. monoalkyl ethers of poly(ethylene oxide) with diepoxides in the presence of a basic catalyst, converting a part of the ∼OH groups into ∼OCσ end groups (alkoxide anions). Analysis of the structure of these macromolecules was mostly based on 1H NMR, MALDI‐TOF, and SEC with triple detection. The absolute values of Mw (LS), Mw/Mn, and [η] are given, indicating formation of macromolecules of high molar mass and highly branched. The number of branches was estimated by several methods, including comparison of the Mark‐Houwink (M‐H) dependencies of the obtained products with the M‐H dependence for PEO stars with exactly known number of arms. The final stars were phosphorylated at the −OH ended branches. Almost exclusively monoesters of phosphoric acid were found in 31P (1H) NMR.
Atom transfer radical polymerization of vinyl monomers in the presence of tetraethylthiuram disulfide
Authors: Qiu Kun‐Yuan , Li Peng , Chen Xiao‐Ping
Published: July 2003

In situ ATRPs of MMA, St in the presence of TD catalyzed by FeCl3/PPh3 and CuBr2/bpy have been studied, respectively. The results showed that the initiator Et2NCS2X (X = Cl or Br) and catalyst FeCl2 or CuBr were formed in situ from the initiating components and the polymerization exhibited living radical polymerization characteristics. In the case of St polymerization with TD/CuBr/bpy initiating system, an inverse ATRP was observed.
Ethene‐butadiene copolymers by single‐site catalysts
Authors: Kaminsky Walter , Hinrichs Benjamin
Published: July 2003

Constrained geometry catalysts ([Me2Si(NtBu)(Me4Cp)]TiCl2) were used to copolymerize ethene and 1,3‐butadiene. It is possible to incorporate 17 mol% of butadiene, other catalyst systems such as CpTiCl3/MAO show much lower incorporation. More than 300 000 kg of copolymer can be obtained by one mol of the catalysts in one hour. The microstructure of the copolymers has been investigated by 1H‐ and 13C‐NMR spectroscopy. The butadiene is incorporated mainly in 1,4‐trans‐ and 1,2‐structure. The high amount of 9‐29% of vinyl groups offers the possibility of an easy vulcanisation. The molecular weights of these elastomers are high with values of 250 000. Important is the low glass transition temperature of −28 °C of a copolymer with 7 mol% of butadiene.
Synthesis of polyolefins with unique properties by using metallocene‐type catalysts
Authors: Imanishi Yukio , Naga Naofumi , Tsubooka Michiyo
Published: July 2003

Copolymerization of ethylene and 1,5‐hexadiene (HD) by zirconocene catalysts proceeded via cyclization‐addition mechanism to form 1,3‐didsubstituted cyclopentane structure in the polyethylene chain. The 1,3‐cyclopentane structure was found to be taken in the crystalline structure of polyethylene (isomorphism) by partially chainging the trans zigzag chain into gauche conformation, thereby, inducing a transformation of orthorhombic crystal to pseudohexagonal crystal. Copolymerization of ethylene and cyclopentene (CPE) by zirconocene catalysts yielded copolymers having 1,2‐disubstituted cyclopentane structure in the polyethylene chain. The 1,2‐cyclopentane structure was not taken into the crystalline structure of polyethylene. The melting point (Tm) and the crystallinity (Xc) of polyethylene decreased by copolymerization of HD or CPE, and the Tm‐ and Xc‐decreasing effect of CPE was stronger than HD. For copolymers of propylene and HD or CPE obtained with isospecific zirconocene catalyst, the isomorphism was not ovserved.
Syntheses and characterizations of polypropene, polystyrene and their block copolymers with titanocene catalysts
Authors: Lin Shangan , Wu Qing , Chen Rui , Zhu Fangming
Published: July 2003

Pentamethylcyclopentadienyltitanium tribenzyloxide, Cp*Ti(OBz)3, was used as the catalyst precursor for polymerizations of propene and styrene. The titanocene catalyst affords atactic polypropene and syndiotactic polystyrene with high activities in the presence of methylalumimoxane (MAO). Block copolymerization of propene and styrene was carried out in the presence of Cp*Ti(OBz)3/MAO catalyst system by the means of external addition of triisobutylaluminum (TIBA) and sequential monomer feed. The copolymerization product is mainly a mixture of atactic polypropene(aPP) and syndiotactic polystyrene(sPS) homopolymers and aPP‐b‐sPS block copolymers, which can be separated into fractions with successive extraction with boiling methylethyl ketone(MEK), heptane, tetrahydrofuran(THF), and chloroform. Studies on thermal properties showed that rubbery phases and crystalline regions both appear in the block copolymer at the room temperature and that aPP‐b‐sPS block copolymer has better toughness than sPS.
Recent advances in the anionic synthesis of chain‐end functionalized polymers
Authors: Quirk Roderic P. , Cheong Tae‐Hee , Jiang Kevin , Gomochak Deanna L. , Yoo Taejun , Andes Keith T. , Mathers Robert T.
Published: July 2003

Recent results for the preparation of chain‐end functionalized polymers using alkyllithium‐initiated anionic polymerization are described. Termination with 4‐chloro‐1,1,1‐trimethoxybutane has been used to prepare trimethoxy ortho ester (carboxyl)‐functionalized polymers. Functionalization with the oxiranes, glycidoxypropyltrimethoxysilane, 3,4‐epoxy‐1‐butene and 1,1,1‐trifluoro‐2,3‐epoxypropane, has been investigated to prepare trimethoxysilyl‐functionalized polymers, 1,3‐diene‐functionalized macro monomers and trifluoromethyl‐functionalized polymers, respectively. Secondary amine‐functionalized polymers have been prepared by termination with N‐(benzylidene)methylamine and also using an N‐benzyl tertiary amine‐functionalized alkyllithium initiator followed by hydrogenolysis of the benzyl group.
Stereocontrol using Lewis acids in radical polymerization
Authors: Okamoto Yoshio , Habaue Shigeki , Isobe Yutaka , Suito Yoshikatsu
Published: July 2003

The radical polymerization of various (meth)acrylamides in the presence of Lewis acids such as Yb(OTf)3 and Y(OTf)3 was carried out. The polymerization with Lewis acids led to highly isotactic polymers, while the polymers synthesized without Lewis acids were atactic or syndiotactic. The dependence of the polymer properties on the tacticity was also demonstrated.
Homo‐ and copolymerization of styrene using combined diphenylzinc‐additive initiator systems
Authors: Rabagliati Franco M. , Pérez Mónica A. , Cancino Rodrigo A. , Rodríguez Francisco J. , Caro Carlos J.
Published: July 2003

Combined systems including diphenylzinc, Ph2Zn, a metallocene, and methylaluminoxane, MAO, have been employed to initiate styrene polymerization and the copolymerization of styrene with p‐alkylsubstituted styrenes and α‐olefins. Both polymerization and copolymerization processes depend on the nature of the metallocene included in the initiator system, the presence of Ph2Zn, the temperature, and the solvent used. S/1‐alkene copolymers were obtained when the initiator systems included a zirconocene, but not when a titanocene participated.