bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanistic aspects of polysaccharide complexation by quaternary ammonium salts, based on the reaction of Xanthan gum with [1‐14C]cetyltrimethylammonium bromide (Part II)
Authors: Kennedy John F. , Bradshaw Ian J. , Barker S. Alan 
Published: April 2007

AbstractComplex formation between cetyltrimethylammonium bromide (CTAB) and xanthan gum in Xanthomonas campestris fermentation broth has been further used to exemplify the reaction between carboxy group — containing polysaccharides and quaternary ammonium salts. The variation of the molar ratio of xanthan gum: CTAB in the supernatant with variation of addition of quaternary ammonium salt is one parameter of the reaction which shows a definite relationship. Although this molar ratio in the supernatant is high (> 1) during the initial stages of the reaction, when little precipitation of the polysaccharide is occurring; it appears that the ratio must be below a critical value of about one before the end‐point of the complexation reaction can occur. The molar ratio of xanthan gum:CTA in the complex is initially exaggerated due to precipitation of polysaccharide with uncomplexed carboxy groups, but this ratio attains a constant value during the final stages of the reaction. A surprising observation of this study was the evidence obtained that CTAB added to X. campestris fermentation broth in excess of the complexation reaction end‐point requirement is associated with the insoluble xanthan gum‐CTA complex and is not present in the supernatant. Several possible explanations have been put forward to account for this observation. On the basis of this and another recent study, a detailed model of the mechanism of the complexation reaction between xanthan gum and CTAB in aqueous solution has been proposed. Discussion has been given to the implications and applicability of this particular complexation reaction mechanism.
The synthesis of the cyclolinear polyphosphazene
Authors: Kajiware M. , Kurachi Y. 
Published: April 2007

AbstractThe reaction of N,N‐diethylphosphoamidic dichloride and diaminotetraaryloxy‐cyclotriphosphazene in THF did not form a cyclolinear polyphosphazene. On the other hand, N,N‐diethylphosphoryltriamide with hexachloro‐cyclotriphosphazene in chloroform and triethylamine gave a product which was reacted with sodium phenoxide in THF solvent to give an amorphous solid, having a molecular weight distribution of 2,200–37,000. Proton n.m.r. indicated that nongeminal substitution had occurred. The product afforded non flammable films.
Direct determinations of the unperturbed dimensions of linear polyethylene molecules
Authors: Muraoka Yoichiro , Kamide Kenji , Suzuki Hidematsu 
Published: April 2007

AbstractLight scattering measurements were carried out on three linear polyethylene samples in diphenyl at 127.5°C, i.e., under theta conditions. The unperturbed molecular dimensions and hence the characteristic ratio Cn were directly determined without recourse to theory for the excluded volume effect. It was found that the values of Cn were 8.7 to 10.5 in this theta solvent. These values suggest that the parameters, assigned to agree with the Cn value of 6.7, should be re‐examined for the refinement of theory.
Structural differences exhibited by networks prepared by chemical or photochemical reactions II — Thermoelastic properties
Authors: Haidar Bassel , Vidal Alain , Donnet Jean‐Baptiste 
Published: April 2007

AbstractThermoelastic properties and swelling measurements were used to characterise networks obtained either by peroxide curing or by photocrosslinking.In agreement with previous studies, it was shown, on the one hand that the measured value of the average molecular weight of a network strand (Mc) depends on its method of determination and that the ratio McT/Mcv2m is a characteristic of each crosslinking process, on the other hand photo‐crosslinked materials exhibit a more homogeneous distribution of the crosslink points than do peroxide cured samples.Important parameters such as fe/f, the energetic contribution to the equilibrium retractive force, and d In < r2> 0/dT, the temperature coefficient of the unperturbed dimension of the macromolecular chain, were determined.
Matrix polymerisation of poly(vinylacetate)
Authors: Bezdadea Mariana , Uglea Constantin , Agherghinci Ion 
Published: April 2007

AbstractThe matrix polymerisation of poly(vinylacetate) was investigated. Using scanning electron microscopy and gel permeation chromatography, the morphology and molecular weight distribution of poly(vinylacetate) were determined. The experimental data prove the matrix influence upon the molecular and morphological characteristics of poly(vinylacetate) thus obtained.
Mechanism of reaction of cyanogen bromide‐activated agarose with amines and the solvolysis of amine ligands
Authors: Kennedy John F. , Barnes Junor A. , Matthews John B. 
Published: April 2007

AbstractCyanogen bromide activated agarose is widely employed as the water‐insoluble matrix in immunoadsorption and affinity chromatography for the immobilisation of proteins. A reaction mechanism is presented for the cyanogen bromide activation of the galactan, agarose, the coupling of model amines to the activated carbohydrate matrix and the detachment of ligands. Dansyl (Dns) derivatisation of the acid hydrolysed and unhydrolysed amine derivatives resulting from the reaction of cyanogen bromide‐activated Sepharose® and N‐α‐acetyl‐L‐ornithine reveal the production of arginine, indicating that the amine‐Sepharose conjugate is an O‐substituted isourea. Thin layer chromatography of the Dns‐derivatised unhydrolysed filtrate from the reaction indicated the formation of several derivatives which suggest that the isourea bonds can be cleaved by the solvolytic attack of nucleophiles in the pH range 8–9.5. Nucleophilic attack by amino groups on the amine‐Sepharose conjugates releases N‐monosubstituted guanidine, N1, N2 disubstituted ornithine and substituted ureas.
Lysosomal‘acid’ hydrolases in normal individuals controls and patients with inborn errors of metabolism
Authors: Raine D. Noel , Crossley Jane E. , Kennedy John F. 
Published: April 2007

AbstractUsing commercially available artificial substrates, a number of lysosomal‘acid’ hydrolases in plasma, leucocytes and cultured skin fibroblasts from normal individuals, controls and patients with inborn errors of metabolism affecting lysosomal enzymes have been investigated. The pH optima, Km values and temperature‐activity profiles are reported, but some of the physiochemical parameters of the catalytic properties of the normal enzymes are not those that would be expected for mammalian system. Temperature optima of α‐L‐fucosidase, α‐L‐iduronidase, sphingomyelinase and β‐D‐glucuronidase were different in different sources and differences were seen in different enzymes from the same source. Only sphingomyelinase in leucocytes and α‐L‐iduronidase in leucocytes and fibro‐blasts showed maximum activity at 37°C, with other enzymes showing an unusually high optimum of 50°C or greater. Lysosomal enzymes from patients with inborn errors of metabolism showed maximum activity at the same temperature as observed in normal individuals with the exception of α‐L‐fucosidase, β‐D‐glucuronidase and α‐N‐acetyle‐D‐glucosaminidase in plasma from a patient with mucolipidosis II and β‐D‐glucuronidase in plasma from a patient with mucopolysaccharidosis type IIIA.
Methods of Following Drug Release from Controlled Release Dosage Forms
Authors: Gould Philip L. 
Published: April 2007

AbstractMany new polymeric controlled release drugs delivery systems are currently being marketed. The cornerstone for the development of these new drug presentations is in vitro release testing. This paper outlines the design conditions for such release systems, and factors such as drug solubility, solution diffusivitiy and hydrodynamics, as well as in vitro‐in vivo correlations are discussed. The two main approaches to in vitro release system design are then outlined; the closed rotational systems and the open flow systems.
Electroinitiated and radiation‐induced polymerisation of epoxycyclohexane
Authors: Akbulut Ural , Önal Ahmet M. , Usanmaz Ali , Toppare Levent K. 
Published: April 2007

AbstractLiquid‐state radiation‐induced and electroinitiated polymerisations of epoxycyclohexane (ECH) have been investigated. The effect of temperature on the electroinitiated polymerisation rate was also studied. The decrease in monomer concentration during polymerisation was followed by gas chromatographic analysis of electrolysis solutions. The i.r. spectra of the polymers suggested polyether structure. N.m.r. spectra of products indicate that the polymerisation of ECH propagates through the opening of the epoxy rings. Poly(epoxycyclohexane) obtained by both methods are amorphous according to X‐ray analyses.
Radiation‐induced and electroinitiated polymerisation of 1, 2‐Epoxy‐4‐epoxyethylcyclohexane
Authors: Onal Ahmet M. , Usanmaz Ali , Akbulut Ural , Toppare Levent 
Published: April 2007

AbstractLiquid state radiation‐induced and electroinitiated cationic polymerisation of 1,2‐epoxy‐4‐epoxyethylcyclohexane (EECH) have been investigated. Soluble and cross‐linked polymers were obtained during the radiation‐induced polymerisation of EECH, depending upon the radiation dose. Electroinitiated polymerisation of the monomer yielded cross‐linked polymers on the surface of the anode. The expected polyether structure was observed for i.r. data. The polymerisation propagates via opening of the epoxy rings as indicated by n.m.r. spectra. X‐Ray analyses showed that the products obtained by both methods are amorphous.
Spectroscopic studies of undoped and doped polystyrene films
Authors: Talway I. M. , Sinha H. C. , Srivastave A. P. 
Published: April 2007

AbstractSpectroscopic (i.r., u.v.) studies of undoped polystyrene and that doped with Acrylic Acid films (30μ thick), prepared by isothermal immersion technique, have been reported. It is found that in the case of i.r. spectra an additional absorption peak appears near 1420cm−1, whereas those present near 1300 and 980cm−1, as shoulders in the undoped sample, appear as sharp peaks in the doped samples. In the region 3300–2500cm−1 a broadening appears in the doped films which increases with the dopant concentration. In the case of u.v. spectra, out of four absorption regions present in the undoped films two bands merge and only three appear in the doped ones. The u.v. absoption increases with the dopant concentration. These results have been explained on the basis of a charge transfer complex formation due to the interaction between the dopant and the polymer matrix.
Studies in heterocyclic polymers Pt VII synthesis and polymerisation of the monomer benzobis (aminoiminopyrrolenine) and synthesis of benzobis (diphenylpyrrolenine)
Authors: Hussain Mohammad , Hodd Kenneth A. 
Published: April 2007

AbstractPyromellitonitrile (1,2,4,5—tetracyanobenzene) and ammonia were reacted under optimum conditions to produce a monomer benzobis (aminoiminopyrrolenine) in high yield. The structure of benzobis (aminoiminopyrrolenine) was established by preparing its derivative pyromellitic diimide, and by infrared and elemental analysis. Benzobis (aminoiminopyrrolenine) was also reacted with aniline to produce a benzobis (diphenylpyrrolenine), a greenish yellow pigment. This monomer benzobis (aminoiminopyrrolenine) was further reacted with 4,4‐diaminodiphenyl ether to give linear and macrocyclic polymers.
A simple 1H N.m.r. Method for the quantitation of O‐acetate ester and pyruvic acid acetal content of polymeric xanthan gum and related polysaccharides
Authors: Kennedy John F. , Stevenson David L. , White Charles A. , Tolley Malcolm S. , Bradshaw Ian J. 
Published: April 2007

AbstractTraditional methods for the quantitation of O‐acetate ester and pyruvic acid acetal in xanthan gums require hydrolysis procedures followed by determination of acetic acid and pyruvic acid separately either by colorimetric, enzymic or chromatographic assays. Some of these assays are time‐consuming and involve many solvent extractions, and during the course of these procedures the xanthan sample is destroyed by hydrolysis. The methyl protons of both O‐acetate ester and pyruvic acid acetal can be detected by 1H n.m.r. spectroscopy, and this paper describes a method for the quantitative determination of these groups on intact polymeric xanthan using an internal integration standard dissolved within the sample. The method is non‐destructive, can be easily performed on a 60MHz spectrometer equipped with Fourier Transformation and variable temperature control, and simultaneously quantitates both O‐acetate ester and pyruvic acid acetal with improved accuracy.
Morphology of poly(hexamethylene oxide) fractions
Authors: Marco Carlos , Fatou José G. , Bello Antonio , López Angeles 
Published: April 2007

AbstractThe supermolecular structure of crystallised molecular weight fractions of poly(hexa‐methylene oxide), covering the molecular weight range (M) 4.5. × 103 to 8. 5 × 104, was studied by polarised light microscopy and small angle light scattering. Different forms were observed as a function of molecular weight and crystallisation temperatures. Perfect spherulites are formed after rapid crystallisation, and these forms deteriorate as both the molecular weight and crystallisation temperature increase. The morphology in the isothermal crystallisation region corresponds to an intermediate state which represents a transition from spherulites to hedrites.
Effects of applied potential on electroinitiated copolymerisation of α‐methylstyrene and β‐bromostyrene
Authors: Toppare Levent , Eren Sami , Akbulut Ural 
Published: April 2007

AbstractElectroinitiated cationic copolymerisation of α‐methylstyrene and β‐bromostryene has been studied at various applied potentials. The relationship between copolymerisation potential and resulting copolymer composition was investigated. The advantages of employing constant potential electrolysis over constant current electrolysis are discussed in terms of the reactivity ratios. The reactivity ratios of the monomers are calculated according to the integrated Lewis‐Mayo equation.
Correlation between the cellulose fibres beating and the fixation of a soluble cationic polymer
Authors: Rouger J. , Mutje P. 
Published: April 2007

AbstractThe amount of cationic soluble polymer fixed by cellulose fibres, whose specific surface area is increased by beating, was determined by a colloidal titration method. A linear relationship between the polymer uptake and the surface density of carboxyl groups was obtained up to a beating degree of 54°SR. For higher values, the uptake was found to be independent of surface carboxyl groups. These results are interpreted in terms of two mechanisms: a fixation of polycations through an ion‐exchange mechanism and an adsorption of polymer by Van der Waals interactions and/or hydrogenbonding.
A rapid method for the assay of alginates in solution using polyhexamethylenebiguanidinium chloride
Authors: Kennedy John F. , Bradshaw Ian J. 
Published: April 2007

AbstractA rapid method for the quantitative assay of alginate in solution over a wide concentration range (0.01–0.5 percent) has been developed using the polymetric cation poly(hexamethylenebiguandinium chloride) [PHMBH+Cl−]. The procedure consists of the addition of a known excess amount of PHMBH+Cl− to alginate solutions to precipitate the sample quantitatively and therafter measuring the u.v. absorption of residual PHMBH+C1− in the supernatant. The working range of the assay can be altered by simply adjusting the excess quantity of PHMBH+Cl− which is added during the assay. Assay response is easily reproducible and insensitive to variation in salt concentration (up to 2.5 per cent), pH (5.5–7.6) and temperature (10–60°C). The PHMBH+Cl− method shows good agreement with another recognised method for the assay of alginate solutions. The simplicity of this new method and the short time required to perform it, enhances its suitability as a quick analytical procedure for alginates. Preliminary evidence suggests that assay response is independent of the D‐mannuronic acid/L‐guluronic acid ratio of alginate.
Electroinitiated and radiation‐induced polymerisation of epoxycyclopentane
Authors: Onal Ahmet M. , Usanmaz Ali , Akbulut Ural , Toppare Levent 
Published: April 2007

AbstractLiquid state radiation‐induced and electroinitiated polymerisations of epoxycyclopentane (ECP) have been investigated. Dichloromethane and tetrabutylammonium hexafluoro‐phosphate were employed as a solvent electrolyte couple. Temperature effects on the rate of electroinitiation were also studied. Apparent activation energy for the electroinitiated polymerisation was calculated from the Arrhenius plot. The propagation of the polymerisation for both methods was found to be through the opening of the epoxy ring, as verified by i.r. and n.m.r. spectra. Both methods of polymerisation yielded tacky, amorphous polymers.
Polydienes possessing terminal ionic groups part 1 preparation of polydienes with terminal quaternary ammonium groups
Authors: Richard D. H. , Service D. M. , Stewart M. J. 
Published: April 2007

AbstractMethods are described by which living anionic polydienes are reacted with α, ω‐alkylene‐chloroamines to generate polymers possessing terminal tertiary amine groups. Subsequent reaction with alkyl halides yields materials with quaternary ammonium terminal ligands. Evidence is presented to show that both reaction steps proceed with high efficiency, so that overall conversion is virtually quantitative.The ionically terminated polydienes exhibit two phase morphology, and the difunctional materials have thermoplastic elastomeric properties.
The trimethylsilylation of sodium silicate. Dependence of yield and molecular weight of the product on various mixing methods
Authors: Kajiwara M. , Yamamoto N. 
Published: April 2007

AbstractThe trimethylsilylation of sodium silicate in solution was carried out using magnetic and ultrasonic mixing. The maximum yield of trimethylsilylated product was obtained by magnetic stirring. The product having the higher molecular weight was formed using ultrasonic as well as magnetic mixing. The product was a white amorphous solid, soluble in most organic solvents.
Experimental control and threats to internal validity of concurrent and nonconcurrent multiple baseline designs
Authors: Christ Theodore J. 
Published: April 2007

AbstractSingle‐case research designs are often applied within school psychology. This article provides a critical review of the scientific merit of both concurrent and nonconcurrent multiple baseline (MB) designs, relative to their capacity to assess threats of internal validity and establish experimental control. Distinctions are established between AB replications and nonconcurrent multiple baseline designed studies using the initial conception proposed by P.J. Watson and E.A. Workman (1981). Despite some previously pessimistic evaluations of nonconcurrent multiple baseline designs, the findings of this review suggest that various threats of internal validity can be assessed and ruled out using either concurrent or nonconcurrent MB designs. It seems that nonconcurrent designs can be used to assess the intervening effects of history, but might be more prone to threats of mortality. These and other threats of internal validity are reviewed and recommendations are provided. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 451–459, 2007.
Dealing with assumptions underlying statistical tests
Authors: Wells Craig S. , Hintze John M. 
Published: April 2007

AbstractThe validity of a hypothesis test is partly determined by whether the assumptions underlying the test are satisfied. In the past, a preliminary analysis of the data has been suggested prior to the use of the statistical test. In this article, the authors describe several limitations of preliminary tests (e.g., influence on significance levels). Another strategy that uses theoretical knowledge in conjunction with prior empirical evidence and reason, prior to data collection, is described. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 495–502, 2007.
Statistical reform in school psychology research: A synthesis
Authors: Swaminathan Hariharan , Rogers H. Jane 
Published: April 2007

AbstractStatistical reform in school psychology research is discussed in terms of research designs, measurement issues, statistical modeling and analysis procedures, interpretation and reporting of statistical results, and finally statistics education. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 543–549, 2007.
Coating lysozyme molecularly imprinted thin films on the surface of microspheres in aqueous solutions
Authors: Yan Chang‐Ling , Lu Yan , Gao Shu‐Yan 
Published: April 2007

AbstractThe polymerization of 3‐aminophenylboronic acid in an aqueous environment was used for the first time to modify polystyrene microspheres for protein (lysozyme) molecular imprinting. Polystyrene microspheres were prepared by styrene polymerization in an aqueous emulsion with poly(vinyl alcohol) as a surfactant. Poly(3‐aminophenylboronic acid) was then grafted onto the surface of the polystyrene microspheres through oxidation by ammonium persulfate in an aqueous solution in the presence or absence of lysozyme or hemoglobin. Rebinding experiments were conducted to establish the equilibrium time and to detect the specific binding capacity and selective recognition. The results indicated that the microspheres, imprinted by the template protein lysozyme or hemoglobin, possessed specific recognition sites on the shells and had a high specific binding capacity for template proteins. The imprinted particles did not need to be ground or sieved and could easily reach the adsorption equilibrium, thus avoiding some problems of the bulk polymer. All these results demonstrate that the particles have potential applications as substitutes for bulk polymers in biological macromolecular affinity studies. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1911–1919, 2007
Principles of nanostructure design with protein building blocks
Authors: Tsai Chung‐Jung , Zheng Jie , Zanuy David , Haspel Nurit , Wolfson Haim , Alemán Carlos , Nussinov Ruth 
Published: April 2007

AbstractCurrently there is increasing interest in nanostructures and their design. Nanostructure design involves the ability to predictably manipulate the properties of the self‐assembly of autonomous units. Autonomous units have preferred conformational states. The units can be synthetic material science‐based or derived from functional biological macromolecules. Autonomous biological building blocks with available structures provide an extremely rich and useful resource for design. For proteins, the structural databases contain large libraries of protein molecules and their building blocks with a range of shapes, surfaces, and chemical properties. The introduction of engineered synthetic residues or short peptides into these can expand the available chemical space and enhance the desired properties. Here we focus on the principles of nanostructure design with protein building blocks. Proteins 2007. © 2007 Wiley‐Liss, Inc.