bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiating Type A behaviour and hyperactivity using observed motivation during a reaction time task
Authors: Nyberg Lilianne , Bohlin Gunilla , Berlin Lisa , Janols Lars‐Olof 
Published: April 2003

AbstractIn light of the previously found overlap between Type A behaviour as measured by the Matthews Youth Test for Health (MYTH) and hyperactivity scales, the overall aim of this study was to clarify the standing of MYTH‐defined Type A behaviour relative to hyperactivity and Attention‐Deficit/Hyperactivity Disorder (ADHD), using observed task motivation and performance on a choice reaction‐time task, the Complex Reaction Time (CRT) measure. This study included 21 boys exhibiting Type A behaviour, 22 ADHD boys, 20 non‐clinically hyperactive boys, and 20 non‐hyperactive boys, between the ages of 6 and 13 years. It was proposed that a differentiation of constructs would be possible using observed task motivation if the MYTH were a discriminantly valid measure of Type A behaviour. Results showed that the MYTH‐defined Type A group differed from the clinically diagnosed ADHD group, although it was markedly similar to the non‐clinical hyperactive group, displaying comparable CRT performance and low level of task motivation. Type A behaviour correlated to CRT performance and task motivation in a way which was conceptually more indicative of hyperactivity than of Type A behaviour, which questions the validity of the MYTH as a measure of the Type A construct. The MYTH Impatience subscale was found to be particularly impure with regard to hyperactivity. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of Self‐Assembly of Sodium Acrylate on the Crystallization of Calcium Carbonate
Authors: Guo Yuming , Yang Lin , Yang Xiaoli , Zhang Xiuying , Zhu Shufa , Jiang Kai 
Published: April 2003

AbstractBased on the primary principles of biomineralization, CaCO3 similar to that in biominerals was synthesized through biomimetic synthesis under the self‐assembly of sodium acrylate. In our experiment, the formation of the calcium carbonate and the polymerization of sodium acrylate took place simultaneously through the appropriate method. The result shows that the self‐assembly process of the sodium acrylate has an important effect on the crystallization and growth of the calcium carbonate. The result is significant for the mimetics of the biomineralization conditions and the research of biomimetic materials synthesis.
SEM of crystal product A.magnified imageSEM of crystal product A.
Influence of Complexing Polyanions on the Thermostability of Basic Proteins
Authors: Ivinova Olga N. , Izumrudov Vladimir A. , Muronetz Vladimir I. , Galaev Igor Yu. , Mattiasson Bo 
Published: April 2003

AbstractLysozyme (Lyz), chymotrypsinogen (Cht), and glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) were used as model proteins capable of forming water‐soluble polyelectrolyte complexes with linear synthetic polyanions. The complex formation with sodium poly(methacrylate) (PMA), sodium poly(acrylate) (PAA), sodium poly(anetholsulfonate) (PAS), and potassium poly(vinylsulfate) (PVS) markedly reduced the temperature of protein denaturation, Tmax, as determined by differential scanning calorimetry (DSC). The effect of sodium poly(styrenesulfonate) (PSS) on Lyz was so drastic that the protein melting peak was not observed at all during DSC measurements. The temperature shift, most pronounced for Lyz, increased upon substitution of the polyanions according to the following series: PMA < PVS < PAA < PAS < PSS. Decomposition of the complexes by addition of either sodium chloride or poly(N‐ethyl‐4‐vinylpyridinium) cation completely restored the initial Tmax of the protein (except for PSS and PAS). The complex formation slightly affected the enzyme activity up to temperatures close to Tmax of the polyanion–protein complex. On further heating, the activity of the complex decreased steeply, whereas the free enzyme maintained a high activity. The data obtained strongly suggest that the protein–polyelectrolyte interactions in solution, while leaving the thermostability and activity of the proteins practically unaffected over a rather wide temperature range, result in the effective denaturation of proteins once a certain critical temperature is achieved. This finding appears to be crucial for further development of immobilized enzymes in biotechnology and essential for understanding mechanisms and principles of the functioning of proteins immobilized on charged matrices in vivo.Temperature dependence of partial heat capacity ΔCp of free Lyz and Lyz in the mixtures with PMA.magnified imageTemperature dependence of partial heat capacity ΔCp of free Lyz and Lyz in the mixtures with PMA.
Asymmetric induction radical copolymerization of (−)‐3‐menthyl hydrogen maleate with styrene
Authors: Kurokawa Masahiro , Minoura Yuji 
Published: April 2003

AbstractRadical copolymerizations of (−)‐3‐menthyl maleate (1) were carried out with styrene, with indene, and with isobutyl vinyl ether. The copolymers were hydrolyzed with potassium hydroxide. After hydrolysis the copolymers were still optically active, due to an introduction of asymmetry into the main chain of the copolymer. The mechanism of asymmetric induction and the position of the new asymmetric center are discussed based on measurements of UV spectra, optical rotation, optical rotatory dispersion, and circular dichroism.
Enzymes immobilisées, 12. Emploi de polyacrylamides, contenant des groupes hydroxy méthyles pour l'immobilisation de l'invertase, de la glucose oxydase, de l'α‐chymotrypsine, de l'uréase et de la β‐galactosidase
Authors: Brown Eric , Touet Joël 
Published: April 2003

AbstractInvertase, glucose oxidase, α‐chymotrypsin, urease, and β‐galactosidase were immobilized on polymers 2a or 2b (in bead or gel form), using p‐benzoquinone or cyanogen bromide as activating reagents. The resulting insoluble derivatives were found to have high total enzymatic activities (76–83% in the case of invertase) retaining 62 to 84% of their initial activity after storing for 3 to 8 weeks. On the other hand, a column of β‐galactosidase immobilized on Trisacryl‐H was used for 120 h continuous production of glucose.
Functional Polystyrene Combs and Dendrigrafts, 1
Authors: Schappacher Michel , Bernard Julien , Deffieux Alain 
Published: April 2003

AbstractPeripherally functionalized arborescent polystyrenes (PS) of various architectures and chain parameters (backbone DPn, number and DPn of branches, number of termini and functions) were prepared by covalently assembling different elementary building blocks of controlled DPn, synthesized using anionic and cationic polymerization techniques. These multifunctional dendritic macromolecules have narrow polydispersities (< 1,2), and exhibit molar masses ranging from 1 × 105 to 5 × 106 g/mol for combs, and from 3 × 106 to 13 × 106 g/mol for dendrigrafts. In this latter series the number of terminal bis(hydroxymethyl) functions per macromolecule can be as high as 2 000. The calculated loading capacity (number of functional groups/g of polymer) was found to depend mainly on the molar mass of the last PS building block. It can approach 10−3 eq/g for low PS DPn grafts (DPn ≈ 10).
First generation dendrigrafts.magnified imageFirst generation dendrigrafts.
Polymer Nanoparticles with Activated Ester Surface by Using Functional Surfmers
Authors: Herold Marc , Brunner Herwig , Tovar Günter E. M. 
Published: April 2003

AbstractTwo new polymerizable surfactants (surfmers), p‐[11‐(acrylamido)‐undecanoyloxy]phenyldimethylsulfonium methylsulfate (AUPDS) and p‐[11‐(methacrylamido)undecanoyloxy]phenyldimethylsulfonium methylsulfate (MUPDS), were synthesized and used for the preparation of functional polymer nanoparticles. The surfmers were characterized (cmcAUPDS = 6.0 ± 0.2 mmol · L−1; cmcMUPDS = 3.2 ± 0.2 mmol · L−1) and employed in emulsion polymerization with methyl methacrylate as a comonomer. Depending on the surfmer‐to‐comonomer ratio, the resulting particles had a dynamic light scattering diameter between 109 nm and 167 nm. Scanning electron microscopy confirmed a very narrow size distribution. The particles showed a ζ‐potential of 20 to 24 mV as measured by micro‐electrophoresis, corresponding to the electrostatic stabilization by the positively charged sulfonium group of the surfmer. The reactivity of the particle bound active ester was determined by titration of the latex with a fluorescent probe and subsequent fluorescence analysis. 6‐Aminofluoresceine was immobilized from 0.8 μmol to 9.6 μmol per 1 g particles depending on the AUPDS starting concentration in emulsion polymerization.
Scanning electron microscopy images of poly(MMA‐co‐AUPDS) particles (sample PA 6, 0.25 mol‐% AUPDS) showing the narrow size distribution over a larger sample area.magnified imageScanning electron microscopy images of poly(MMA‐co‐AUPDS) particles (sample PA 6, 0.25 mol‐% AUPDS) showing the narrow size distribution over a larger sample area.
Photoinduced Changes of the Refractive Index in Substituted Fluorenyl‐p‐phenylene Copolymers
Authors: Schöfberger Wolfgang , Zaami Noreddine , Mahler Kai Arnulf , Langer Gregor , Jakopic Georg , Pogantsch Alexander , Kern Wolfgang , Stelzer Franz 
Published: April 2003

AbstractA series of substituted 9,9′‐dihexylfluorenylene‐p‐phenylene copolymers (DFPP) were synthesised via a Suzuki coupling reaction. The copolymers were chemically modified to introduce photoreactive functionalities. Thiocyanate groups (SCN) were attached onto a side chain of the DFPP copolymers. After exposure to UV light the SCN groups underwent photoisomerisation to the corresponding isothiocyanate groups (NCS). A significant change of the refractive index was observed after UV illumination. After this process the polymer was further modified by a gas phase reaction with propylamine to transform the photo‐generated NCS groups to derivatives of thiourea. An additional variation of the refractive index, as well as an increase of the film thickness h(Δh + 15%), was observed after this reaction. All polymerisation products were characterised by means of gel permeation chromatography, thermoanalysis as well as NMR and IR spectroscopy. The polymers are thermally stable with decomposition temperatures of around 260 °C and glass transition temperatures in the range of 150–155 °C. The polymers display blue photoluminescence, which remains unchanged after UV modification and reaction with propylamine. A convenient way to produce index and relief patterns in films of conjugated polymers is demonstrated.
Photoreactive DFPP copolymer and modified products.magnified imagePhotoreactive DFPP copolymer and modified products.
Solution properties of polybutadiene and trans‐polyisoprene fractions
Authors: Cooper W. , Eaves D. E. , Vaughan G. 
Published: April 2003

AbstractLinear polybutadienes, prepared with butyllithium as catalyst, and polybutadienes branched by exposure to γ‐radiation have been fractionated and the fractions examined by osmometry and light scattering. Turbidimetric second virial coefficients (A2τ) of mixed polymer fractions are virtually the same as those of the higher molecular weight components of the mixtures for most compositions. This is true both for mixtures of linear with linear and linear with branched polymer. The higher the molecular weight of the fraction, the greater the effect; the addition of 1% microgel to a linear polymer reduced A2τ by a factor of three. The presence of microgel or high molecular weight branched polymer has been shown to be responsible for the very high molecular weights previously reported for polybutadienes from light scattering measurements. It is conveniently removed by shaking the solutions with calcium sulfate. Second virial coefficients obtained either by light scattering or osmometry are, within the limits of experimental error, uninfluenced by branching in the polymer. In general those factors which lead to increased branching also result in increased polydispersity, and it is the latter which results in the decrease in A2τ. The fall of the osmotic second virial coefficient (A2τ) with molecular weight is much smaller than would be calculated theoretically, and the fall in A2τ is greater than would be expected, notwithstanding the fact that for some of the fractions M̄u/M̄n < 1.1. This indicates that A2π is sensitive to the low molecular weight species presented in the fractions, whereas the reverse must apply to A2τ. Natural of synthetic trans‐polyisoprene showed analogous behavior to polybutadiene, although, owing to experimental difficulties, sharp branched fractions could not be obtained. The following viscosity–molecular weight relationships were obtained in benzene solution: [η] = 1.45 × 10−4M0.76 for butyllithium‐catalyzed polybutadienes, and [η] = 4.37 × 10−4M0.65 for natural and synthetic trans‐polyisoprenes.
Proton magnetic resonance absorption in dry nylons 66 and 610
Authors: Jones D. W. 
Published: April 2003

AbstractA comparison of the temperature dependence of the nuclear resonance line‐width and second moment for dried chip and rod samples of nylon 66 and 610, as measured by several authors, reveals discrepancies within the range 80 to 400°K. Room temperature measurements with a Pound‐Watkins spectrometer suggest that neither linewidth nor second moment varies greatly with radiofrequency field, although saturation may occur at low temperatures. It is concluded that the nuclear resonance differences reflect sample differences, at least for the higher temperatures. Evidence is considered for the decomposition of the continuous nuclear resonance changes in polyamides into more discrete “transitions;” in nylon 66, there are nuclear resonance effects near 120, 200, 330, and 370°K.
Molecular conformation of linear polyphosphonitrile chloride
Authors: Giglio E. , Pompa F. , Ripamonti A. 
Published: April 2003

AbstractThe interpretation of the x‐ray fiber photograph of stretched linear polyphosphonitrile chloride was carried out by means of Fourier transform methods with the aim of establishing the chain conformation without considering the mode of packing in the crystal lattice. The results of such an analysis lead to the conclusion that the radial distribution of the intensities on the layer lines is consistent with a twofold helical conformation characterized by values of 156° and 14° for the angles of rotation around the PN and NP bonds, the cis‐planar conformation corresponding to angles of rotation of π and 0°.
A general treatment of equilibrium copolymerization
Authors: Tobolsky A. V. , Owen G. D. T. 
Published: April 2003

AbstractA general theory of equilibrium copolymerization is developed. The theory is compared with published experimental results on sulfur‐selenium copolymers. The equilibrium constants developed previously for sulfur and for selenium homopolymerization are utilized in this new copolymerization theory, and no other mathematical assumptions are made. The theory gives a quite remarkable agreement with the experimental results.
Investigation of polyethylene with the analytical ultracentrifuge
Authors: Moore Louis D. , Greear George R. , Sharp John O. 
Published: April 2003

AbstractA technique has been developed for studying polyethylene with the Spinco Model E analytical ultracentrifuge. 1‐Chloronaphthalene at 120°C. is used as the solvent. A variety of whole polymers from several sources was studied and found to differ considerably in the distribution of their sedimentation rates. Most of the low‐density polyethylenes exhibited a high molecular weight tail (that is, a fast‐moving fraction), whereas a high‐density sample showed a low molecular weight tail. In general, the ultracentrifuge Schlieren patterns showed a direct correlation with light‐scattering results—polymers with high weight‐average molecular weights showed broad patterns containing fastmoving tails. There was also a direct correlation between broad patterns and high values for the Flory expansion factor, α. An exception to the agreement between high weight‐average molecular weight and broad Schlieren pattern was found for a sample (B‐1) which was shown by electron microscopy to have very large molecules present in its make‐up. These large molecules, because of their size, greatly influence the light scattering measurements but, because they were present in relatively small numbers, they were not observed in the Schlieren pattern. A number of fractions were also investigated. The Schlieren patterns obtained with fractions prepared by the Guillet et al. adaptation of the chromatographic method of Baker and Williams were sharper than those obtained with fractions prepared by the extraction method of Desreux and Spiegels. Estimates of the degrees of long‐chain branching were made from measurements of intrinsic viscosities and sedimentation rates of fractions. A knowledge of the molecular weight is not required for this estimate; therefore, this method has some advantage over the older method involving light scattering measurements. There is an excellent correlation between the number of branches per molecule and the intrinsic viscosity for a number of fractions obtained from a low‐density polyethylene of broad distribution. This result is predicted from the theoretical considerations of Beasley. It was also found that fractions from polyethylenes of narrower distribution contained fewer branches per molecule than fractions of comparable intrinsic viscosity from a polymer of broader distribution. This result confirms Beasley's theory that the long‐chain branching mechanism is responsible for the broad molecular weight distributions in low‐density polyethylenes. These differences in branching and molecular weight distribution are most likely responsible for many of the differences in behavior among various polyethylenes.
Chemical transformation of insoluble copolymers of styrene
Authors: Trostyanskaya E. B. , Losev I. P. , Tevlina A. S. , Makarova S. B. , Nefedova G. Z. , Syan'‐Zhao Lu 
Published: April 2003

AbstractWith the objective of synthesizing various insoluble polyelectrolytes and complexes, the chemical reactions of insoluble styrene copolymers (styrene–divinylbenzene or styrene–diallyl maleate) and of copolymers which become insoluble during the synthesis (styrene–butadiene) were studied. By substituting the chlorine atom in chloromethylated copolymers for ionic and complexogenic groups new polymer ion exchangers and complexes have been obtained. Chloromethylation of the copolymers was accomplished with the aid of paraformaldehyde and hydrogen chloride in the presence of zinc chloride in dichloroethane (copolymer I). The extent of conversion is determined by the structure and swelling capacity of the polymer and varies between 65 and 95%. The chlorine atom of copolymer I is completely replaced by an amino group under the action of triethanolamine (copolymer II). The polyelectrolytes formed possess the properties of quaternary ammonium bases with basicity 2.6–2.9 meq./g. The high swelling capacity of copolymer II has been utilized for investigating the possibility of polymerizing vinyl derivatives in the copolymer network. The polymerization of α‐methylvinylpyridine in copolymer II granules leads to a polymer‐in‐copolymer system containing up to 30% polymer and incapable of separation by extraction. The basicity of such a system attains a value of 5.1 meq./g. The replacement of chlorine in copolymer I by phosphine or sulfides gave new insoluble polymer of the phosphonium (copolymer III) or sulfonium (copolymer IV) type. A comparative study has been made of the properties of the ammonium, phosphonium, and sulfonium salts. From copolymer II insoluble complexes containing an aminotriacetic or aminodiacetic acid group
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or a β′, β″, β‴‐triaminotriethylamine group
magnified image
have been obtained. The instability constants of the Ni++, Cu++, Ca++, and Zn++ complexes with the insoluble polymeric complexes have been determined.
Copolymerization characteristics of sodium styrenesulfonate
Authors: Grabiel C. E. , Decker D. L. 
Published: April 2003

AbstractThe reactivity ratios (r1 and r2) of sodium styrenesulfonate (M1) with different monomers in aqueous solution were determined by the usual procedures of copolymerization to low conversion followed by isolation and analysis of the copolymer. The values of r1 and r2, respectively, for the monomers (M2) studied were found to be: acrylonitrile, 1.5, 0.05; acrylic acid, 1.0, 0.10; and sodium acrylate, 2.3, 0.34. The substitution of the sodium salt for the potassium salt of styrenesulfonic acid did not alter the reactivity of the monomer. The Q and e values determined for sodium styrenesulfonate in aqueous solution are 2.0 and −0.4, respectively. The values previously published for potassium styrenesulfonate in dimethylformamide solution, 9.18 and 1.32, respectively, indicate that the styrenesulfonic acid is a highly reactive monomer containing a vinyl group with a polarity strongly positive with respect to styrene. However, the Q and e values presented here denote a reactive monomer with the vinyl group polarized only slightly more positive than styrene. The consequences of these differences are shown in the prediction of copolymer compositions.
New Direction in Organopalladium Chemistry: Structure and Reactivity of Unsaturated Hydrocarbon Ligands Bound to Multipalladium Units
Authors: Murahashi Tetsuro , Ogoshi Sensuke , Kurosawa Hideo 
Published: April 2003

AbstractExamination of the manner of interaction between Pd(0) and allylpalladium(II) complexes, both being involved
as key intermediates in Pd‐catalyzed allylic coupling, led us to discover a new role for such combinations in affecting the
stereochemistry of the transformations. A similar investigation of the system involving Pd(0) and allenyl/propargyl
complexes of Pd(II) led to the discovery of dinuclear Pd(I)Pd(I) complexes containing bridging
allenyl/propargyl ligands, which exhibited novel structural and reactivity aspects of great synthetic significance. A systematic
comparison was made between the structure, stability, and reactivity of allyl and allenyl/propargyl ligands in dinuclear complexes
and those in mononuclear counterparts. On the basis of MO calculations, coordination behavior specific to the ligands of the dinuclear
complex is attributed to the occurrence of the back‐donating interaction from filled PdPd bonding orbitals to vacant
ligand π* orbitals. Similar bonding features are the origin of the ready synthesis of novel one‐dimensional sandwich
complexes composed of conjugated polyene ligands and linear polypalladium chains. A substitutionally labile dipalladium complex reacts
with an equimolar amount of trienes or alkynes to give formal [4π + 2σ] or
[2π + 2σ] adducts, respectively, which undergo further unique transformations with additional
unsaturated substrates. © 2003 The Japan Chemical Journal Forum and Wiley Periodicals, Inc., Chem Rec 3: 101–111; 2003:
Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10052