bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of force profile during a maximum voluntary isometric contraction task
Authors: Househam Elizabeth , McAuley John , Charles Thompson , Lightfoot Timothy , Swash Michael
Published: February 2004

This study analyses maximum voluntary isometric contraction (MVIC) and its measurement by recording the force profile during maximal‐effort, 7‐s hand‐grip contractions. Six healthy subjects each performed three trials repeated at short intervals to study variation from fatigue. These three trials were performed during three separate sessions at daily intervals to look at random variation. A pattern of force development during a trial was identified. An initiation phase, with or without an initiation peak, was followed by a maintenance phase, sometimes with secondary pulses and an underlying decline in force. Of these three MVIC parameters, maximum force during the maintenance phase showed less random variability compared to intertrial fatigue variability than did maximum force during the initiation phase or absolute maximum force. Analysis of MVIC as a task, rather than a single, maximal value reveals deeper levels of motor control in its generation. Thus, force parameters other than the absolute maximum force may be better suited to quantification of muscle performance in health and disease. Muscle Nerve 29: 401–408, 2004
Specific assembly pathway of sarcoglycans is dependent on beta‐ and delta‐sarcoglycan
Authors: Shi Weixing , Chen Zaili , Schottenfeld Jodi , Stahl Richard C. , Kunkel Louis M. , Chan Yiu‐Mo
Published: February 2004

Mutations in sarcoglycans (SG) have been reported to cause autosomal‐recessive limb‐girdle muscular dystrophy (LGMD) and dilated cardiomyopathy. In skeletal and cardiac muscle, sarcoglycans exist as a complex of four transmembrane proteins (α‐, β‐, γ‐, and δ‐SG). In this study, the assembly of the sarcoglycan complex was examined in a heterologous expression system. Our results demonstrated that the assembly process occurs as a discrete stepwise process. We found that β‐SG appears to play an initiating role and its association with δ‐SG is essential for the proper localization of the sarcoglycan complex to the cell membrane. The incorporation of α‐SG into the sarcoglycan complex occurs at the final stage by interaction with γ‐SG. These findings were supported by chemical cross‐linking of endogenous sarcoglycans in cultured myotubes. We have also provided evidence that glycosylation‐defective mutations in β‐SG and a common mutation in γ‐SG (C283Y) disrupt sarcoglycan‐complex formation. Our proposed model for the assembly and structure of sarcoglycans should generate important insight into their function in muscle as well as their role in muscular dystrophies and cardiomyopathies. Muscle Nerve 29: 409–419, 2004
Epidermal nerve fiber density, axonal swellings and QST as predictors of HIV distal sensory neuropathy
Authors: Herrmann David N. , McDermott Michael P. , Henderson Don , Chen Lin , Akowuah Kwame , Schifitto Giovanni ,   the North East Aids Dementia (NEAD) Consortium
Published: February 2004

We investigated the associations of baseline epidermal nerve fiber (ENF) densities and morphology (percent ENF swellings) and quantitative sensory testing (QST) with clinically defined human immunodeficiency virus (HIV)‐associated distal polyneuropathy (DSP) and whether these measures are predictive of development of symptomatic DSP over time. Fifty‐seven HIV‐infected subjects with and without DSP and 19 controls participated. Mean ENF densities were lower at the distal leg and proximal thigh in asymptomatic or symptomatic DSP than in controls. Mean ENF densities did not differ significantly among the HIV groups. Percent ENF swellings was higher in patients with symptomatic DSP than controls at the distal leg, and was also greater at the proximal thigh in patients with asymptomatic or symptomatic DSP than in controls. The percent ENF swellings at the distal leg correlated with the thresholds for both minimal (HP 0.5) and intermediate (HP 5.0) heat pain (HP) intensity. A higher percent ENF swellings in the distal leg [hazard ratio (HR) 1.16, 95% CI 1.02–1.31] and HP 0.5 thresholds (HR 1.03, 95% CI 1.01–1.05) were the only two measures associated with a shorter time to development of symptomatic DSP. Quantitation of ENF swellings and heat pain thresholds deserve further study as predictors of symptomatic neuropathy. Muscle Nerve 29: 420–427, 2004
Effect of muscle creatine content manipulation on contractile properties in mouse muscles
Authors: Eijnde Bert O. , Lebacq Jean , Ramaekers Monique , Hespel Peter
Published: February 2004

The effects of muscle creatine manipulation on contractile properties in oxidative and glycolytic muscles were evaluated. Whereas control mice (NMRi; n = 12) received normal chow (5 g daily), three experimental groups were created by adding creatine monohydrate (CR group; 5%, 1 week; n = 13); β‐guanidinoproprionic acid, an inhibitor of cellular creatine uptake (β‐GPA group; 1%, 2 weeks; n = 12); or CR following β‐GPA (β‐GPA+CR group; n = 11). Total creatine (TCr) and the contractile properties of incubated soleus and extensor digitorum longus (EDL) muscles were determined. For the soleus, compared with control, TCr increased in the CR group (+25%), decreased in β‐GPA group (−50%), and remained stable in the β‐GPA+CR group, whereas, for the EDL, TCr was similar in the CR, and lower in the β‐GPA (−40%) and β‐GPA+CR (−15%) groups. None of the experimental groups (CR, β‐GPA, or β‐GPA+CR) showed changes in peak tension (Ppeak), time to peak tension, or relaxation in soleus or EDL during twitch or tetanic stimulation. For the soleus, fatigue reduced Ppeak to ∼60% of initial Ppeak; 5 min of recovery restored Ppeak to values ∼15% higher in CR than in controls. Ppeak recovery was not affected by β‐GPA or β‐GPA+CR in the soleus or any treatment in the EDL. Thus, peak tension recovery is enhanced by creatine intake in oxidative but not glycolytic muscles. This may be implicated in the beneficial action of creatine loading. Muscle Nerve 29: 428–435, 2004
Full publication of abstracts of randomised controlled trials published at International Continence Society meetings'
Authors: Herbison Peter
Published: February 2004

Aims

To find out how many abstracts reporting randomised controlled trials (RCTs) that are submitted to scientific meetings of the International Continence Society (ICS) are later published in full, and any predictors of full publication.

Materials and Methods

The appropriate issues of “Neurourology and Urodynamics” and the Proceedings of the ICS for 1998 and 1999 were hand‐searched for the abstracts reporting RCTs. Bibliographic databases (Cochrane Controlled Trials Register, MEDLINE, EMBASE, Healthstar, Psychlit, CINAHL) were searched, using the authors' names, to find full publications. Authors were contacted when no full publication was found to check that all full publications had been found. This was repeated for 1987.

Results

Sixty‐three abstracts reporting RCTs were found in 1998 and 1999. Twenty‐five of these (40%) were followed by full publication. The only characteristic that predicted full publication was the use of a no treatment control group. In 1987, 16 of 19 abstracts (84%) went on to be published in full.

Conclusions

The rate of full publication of abstracts reporting RCTs submitted to recent ICS meetings is low. It is lower than the rate of 56% found in other meetings. As it is widely regarded as unethical not to publish in full, ICS members should make every effort to write‐up studies for peer‐reviewed publication. Neurourol. Urodynam. 23:101–103, 2004. © 2004 Wiley‐Liss, Inc.
Expression of α and β parvalbumin is differentially regulated in the rat organ of corti during development
Authors: Yang D. , Thalmann I. , Thalmann R. , Simmons D. D.
Published: February 2004

The expression of two calcium‐binding proteins of the parvalbumin (PV) family, the α isoform (αPV) and the β isoform known as oncomodulin (OM), was investigated in the rat cochlea during postnatal development and related to cholinergic efferent innervation. Using RT‐PCR analysis, we found that OM expression begins between postnatal day 2 (P2) and P4, and peaks as early as P10, while αPV mRNA begins expression before birth and remains highly expressed into the adult period. Both in situ hybridization and immunoreactivity confirm that OM is uniquely expressed by the outer hair cells (OHCs) in the rat cochlea and occurs after efferent innervation along the cochlear spiral between P2 and P4. In contrast to OM expression, αPV immunoreactivity is expressed in both inner hair cells (IHCs) and OHCs at birth. Following olivocochlear efferent innervation, OHCs demonstrate weak OM immunoreactivity beginning at P5 and diminished αPV immunoreactivity after P10. In organ cultures isolated prior to the efferent innervation of OHCs, OM immunoreactivity failed to develop in OHCs, but αPV immunoreactivity remained present in both IHCs and OHCs. In contrast, organ cultures isolated after efferent innervation of OHCs show OHCs with low levels of OM immunoreactivity and high levels of αPV immunoreactivity. This study suggests that OM and αPV are differentially regulated in OHCs during cochlear development. Our findings further raise the possibility that the expression of PV proteins in OHCs may be influenced by efferent innervation. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 479–492, 2004
Effects of progesterone derivatives, dihydroprogesterone and tetrahydroprogesterone, on the subependymal layer of the adult rat
Authors: Giachino Claudio , Galbiati Mariarita , Fasolo Aldo , Peretto Paolo , Melcangi Roberto C.
Published: February 2004

Indirect evidence suggests that in the subependymal layer (SEL) steroid hormones could be partially involved in the modulation of neurogenesis, but little or nothing is known about a direct effect of these molecules on this cellular system. The possible effect of progesterone (P) and/or its neuroactive metabolites, dihydroprogesterone (DHP) and tetrahydroprogesterone (THP), on the two cellular components of the SEL (i.e., proliferating/migrating neuroblasts and protoplasmic astrocytes) has been analyzed in adult male rat. P, DHP, and THP were administered by intraventricular injections and after 2 days the SEL was analyzed by immunohistochemistry by using anti‐glial fibrillary acidic protein (GFAP) and anti‐vimentin antibodies, to label the glial compartment, anti‐polysialylated form of the neural cell adhesion molecule (PSA‐NCAM), anti‐Stathmin, and anti‐β III Tubulin antibodies to label the migrating neuroblasts. Furthermore, the newly formed cells were identified by using intraventricular injections of 5‐bromo‐2′‐deoxyuridine (BrdU) detected immunohistochemically. Our results demonstrate that DHP and THP treatments drastically decrease the number of BrdU‐labeled cells within the SEL. THP, DHP, and to a lesser extent P, administrations also induce molecular and structural modifications of the SEL glial compartment. On the whole, the present results indicate that neuroactive derivatives of P (i.e., DHP and THP) exert direct effects on adult neurogenesis, strongly affecting both neuroblasts and astrocytes of the SEL. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 493–502, 2004
Differential expression of high voltage‐activated Ca2+ channel types in the rostral reticular thalamic nucleus of the absence epileptic WAG/Rij rat
Authors: van de Bovenkamp‐Janssen M.C. , Scheenen W.J.J.M. , Kuijpers‐Kwant F.J. , Kozicz T. , Veening J.G. , van Luijtelaar E.L.J.M. , McEnery M.W. , Roubos E.W.
Published: February 2004

In the WAG/Rij rat, a model for human absence epilepsy, spike‐wave discharges (SWD) and absence epileptic behavior develop after the age of 3 months. The rostral part of the reticular thalamic nucleus (rRTN) is involved in SWD. Ca2+ channels play a central role in the initiation and maintenance of burst firing activity of thalamic cells. We hypothesize that a changed expression of α1‐subunits of one or more high voltage‐activated Ca2+ channel types in the rRTN underlies the development of SWD. To test this hypothesis we compared 3‐ and 6‐month‐old WAG/Rij rats with nonepileptic, age‐matched control rats. By immunocytochemistry, the expressions of α11.3‐, α12.1‐, α12.2‐, and α12.3‐subunits were shown in both strains, demonstrating the presence of Cav1.3, Cav2.1, Cav2.2, and Cav2.3 channels, respectively. Quantification of channel expression indicates that the development of SWD in WAG/Rij rats is concomitant with an increased expression of Cav2.1 channels in the rRTN. These channels are mainly presynaptic, as revealed by double immunofluorescence involving the presynapse marker syntaxin. The mechanism by which this increase could be related to the occurrence of SWD has been discussed. © 2004 Wiley Periodicals, Inc. J Neurobiol 58: 467–478, 2004
CREB in the pond snail Lymnaea stagnalis: Cloning, gene expression, and function in identifiable neurons of the central nervous system
Authors: Sadamoto Hisayo , Sato Hanae , Kobayashi Suguru , Murakami Jun , Aonuma Hitoshi , Ando Hironori , Fujito Yutaka , Hamano Kaoru , Awaji Masahiko , Lukowiak Ken , Urano Akihisa , Ito Etsuro
Published: February 2004

The pond snail Lymnaea stagnalis is an excellent model system in which to study the neuronal and molecular substrates of associative learning and its consolidation into long‐term memory. Until now, the presence of cyclic AMP (cAMP)‐responsive element binding protein (CREB), which is believed to be a necessary component in the process of a learned behavior that is consolidated into long‐term memory, has only been assumed in Lymnaea neurons. We therefore cloned and analyzed the cDNA sequences of homologues of CREB1 and CREB2 and determined the presence of these mRNAs in identifiable neurons of the central nervous system (CNS) of L. stagnalis. The deduced amino acid sequence of Lymnaea CREB1 is homologous to transcriptional activators, mammalian CREB1 and Aplysia CREB1a, in the C‐terminal DNA binding (bZIP) and phosphorylation domains, whereas the deduced amino acid sequence of Lymnaea CREB2 is homologous to transcriptional repressors, human CREB2, mouse activating transcription factor‐4, and Aplysia CREB2 in the bZIP domain. In situ hybridization revealed that only a relatively few neurons showed strongly positive signals for Lymnaea CREB1 mRNA, whereas all the neurons in the CNS contained Lymnaea CREB2 mRNA. Using one of the neurons (the cerebral giant cell) containing Lymnaea CREB1 mRNA, we showed that the injection of a CRE oligonucleotide inhibited a cAMP‐induced, long‐lasting synaptic plasticity. We therefore conclude that CREBs are present in Lymnaea neurons and may function as necessary players in behavioral plasticity. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 455–466, 2004
Treatment with the antiepileptic drugs phenytoin and gabapentin ameliorates seizure and paralysis ofDrosophilabang‐sensitive mutants
Authors: Reynolds Elaine R. , Stauffer Eric A. , Feeney Laura , Rojahn Elizabeth , Jacobs Benjamin , McKeever Carol
Published: February 2004

Drosophilabang‐sensitive (bs) mutants exhibit a stereotypic seizure and paralysis following exposure to mechanical shock. In a physiological preparation, seizures and failures corresponding to the defective behavior are observed in response to high frequency stimulation. The amplitude of the stimulus necessary to produce bs behavior, or seizure threshold, varies with bs mutant and its gene dosage. In many respects, the bs defects are similar to those observed in mammalian seizure disorders. Antiepileptic drugs (AEDs) were administered by feeding toeasily shocked2(eas2), a representative bs mutant. The mean recovery times of treated flies were examined in comparison to control cultures. Some of the drugs administered, including carbamazeprine, ethosuximide, and vigabactrin, had little or no effect on the bs behavior ofeas2. Gabapentin, however, showed a reduction in mean recovery time with chronic drug exposure. Phenytoin also had a significant effect on the bs behavior of treated flies. There was a reduction of both mean recovery time and the percentage of flies that displayed bang‐sensitive behavior with both acute and chronic treatment. The adult giant fiber preparation was used to examine the effects of phenytoin physiologically. Treatedeas2flies showed changes in their response to normal stimulation as well as alterations in seizure threshold in response to high frequency stimulation. Gabapentin was also effective against two other bs mutants,bangsenseless1andslamdanceiso7.8, at strain‐specific concentrations, while phenytoin also reduced bang‐sensitive behaviors inbangsenseless1in a dose dependent manner. AEDs, therefore, can be used to dissect aspects of bs behavior and this model may be useful in understanding the underlying basis of seizure disorders. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 503–513, 2004
Tyramine and octopamine have opposite effects on the locomotion of Drosophila larvae
Authors: Saraswati Sudipta , Fox Lyle E. , Soll David R. , Wu Chun‐Fang
Published: February 2004

Biogenic amines are believed to play important roles in producing behaviors. Although some biogenic amines have been extensively studied in both vertebrates and invertebrates, little is known about the effects of trace amines like tyramine and octopamine. We investigated how trace amines affect behaviors using quantitative morphometric methods on Drosophila
TβhnM18 and iavN mutants that have altered levels of tyramine and octopamine. Locomotion of wild‐type and mutant third instar larvae was analyzed using Dynamic Image Analysis System (DIAS) software. We found that TβhnM18 mutants, with elevated tyramine levels and reduced octopamine levels, had a severe locomotion phenotype. Mutant larvae spent much more time in pausing episodes than wild‐type larvae and displayed a reduction in speed and linear translocation. The locomotion phenotype was partially rescued by feeding TβhnM18 larvae octopamine, an effect that could be nullified with simultaneous feeding of tyramine. Feeding TβhnM18 larvae yohimbine, an agent that inhibits the activity of Drosophila tyramine receptors, also improved some locomotion parameters. Feeding both octopamine and yohimbine further improved rescue efficiency. Simultaneously reducing the octopamine and tyramine levels as in iavN larvae, in contrast, led to a less severe behavioral phenotype than that of TβhnM18 mutants. Feeding iavN larvae either tyramine or octopamine exerted only a minor improvement in locomotion. These results suggest that tyramine and octopamine have opposite effects on Drosophila larval locomotion regulation and that a balance between the two is important in producing normal behavior. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 425–441, 2004
Developmental patterns of NMDAR expression within the song system do not recur during adult vocal plasticity in zebra finches
Authors: Scott Luisa L. , Singh Tryambak D. , Nordeen Ernest J. , Nordeen Kathy W.
Published: February 2004

All songbirds learn to sing during postnatal development but then display species differences in the capacity to learn song in adulthood. While the mechanisms that regulate avian vocal plasticity are not well characterized, one contributing factor may be the composition of N‐methyl‐D‐aspartate receptors (NMDAR). Previous studies of an anterior forebrain pathway implicated in vocal plasticity revealed significant regulation of NMDAR subunit expression during the developmental sensitive period for song learning. Much less is known about the developmental regulation of NMDAR subunit expression in regions that participate more directly in motor aspects of song behavior. We show here that an increase in NR2A subunit mRNA and a decrease in NR2B subunit mRNA within the vocal motor pathway accompany song learning in zebra finches; however, manipulations that can alter the timing of song learning did not alter the course of these developmental changes. We also tested whether adult deafening, a treatment that provokes vocal change in songbirds that normally sing a stable song throughout adulthood, would render NMDAR subunit expression more similar to that observed developmentally. We report that NR2A and NR2B mRNA levels did not change within the anterior forebrain or vocal motor pathways after adult deafening, even after substantial changes in song structure. These results indicate that vocal plasticity does not require “juvenile patterns” of NMDAR gene expression in the avian song system. © 2003 Wiley Periodicals, Inc. J Neurobiol 58: 442–454, 2004
Topographic regulation of phosphorylation in giant neurons of the squid, Loligo pealei: Role of phosphatases
Authors: Grant Philip , Pant Harish C.
Published: February 2004

In previous studies of phosphorylation in squid stellate ganglion neurons, we demonstrated that a specific multimeric phosphorylation complex characterized each cellular compartment. Although the endogenous protein profile of cell body extracts (giant fiber lobe, GFL), as determined by Coomassie staining, was similar to that of axoplasm from the giant axon, in this study we show that the protein phosphorylation profiles are qualitatively different. Whereas many axoplasm proteins were phosphorylated, including most cytoskeletal proteins, virtually all phosphorylation in perikarya was confined to low molecular weight compounds (<6 kDa). Because phosphorylation of exogenous substrates, histone and casein, was equally active in extracts from both compartments, failure to detect endogenous protein phosphorylation in cell bodies was attributed to the presence of more active phosphatases. To further explore the role of phosphatases in these neurons, we studied phosphorylation in the presence of serine/threonine and protein tyrosine phosphatase (PTP) inhibitors. We found that phosphorylation of axonal cytoskeletal proteins was modulated by okadaic acid‐sensitive ser/thr phosphatases, whereas cell body phosphorylation was more sensitive to an inhibitor of protein tyrosine phosphatases, such as vanadate. Inhibition of PTPs by vanadate stimulated endogenous phosphorylation of GFL proteins, including cytoskeletal proteins. Protein tyrosine kinase activity was equally stimulated by vanadate in cell body and axonal whole homogenates and Triton X‐100 free soluble extracts, but only the Triton X soluble fraction (membrane bound proteins) of the GFL exhibited significant activation in the presence of vanadate, suggesting higher PTP activities in this fraction than in the axon. The data are consistent with the hypothesis that neuronal protein phosphorylation in axons and cell bodies is modulated by different phosphatases associated with compartment‐specific multimeric complexes. © 2004 Wiley Periodicals, Inc. J Neurobiol 58: 514–528, 2004
Anionic non‐equilibrium ring‐opening polymerization of octamethylcyclotetrasiloxane (D4) initiated by silazyl‐lithiums
Authors: Su Shunxing , Zhang Zhijie , Zheng Zhimin , Xie Zemin
Published: February 2004

The initiation and propagation reactions in anionic non‐equilibrium polymerization of octamethylcyclotetrasiloxane (D4) initiated by silazyl‐lithiums are investigated. It is found that: both the steric hindrance effect and the electronic effect of the substitutes on the Si atom Si influences the initiation activity of silazyl‐lithiums; temperature effect on the propagation rate of D4 increases strongly above 40 °C; the molecular weight distribution of the prepared polysiloxanes widens with time.

© 2003 Society of Chemical Industry
Specific interactions in miscible polymer blends of poly(2‐hydroxypropyl methacrylate) with polyvinylpyrrolidone
Authors: Kuo Shiao‐Wei , Shih Chien‐Chou , Shieh Jye‐Shiou , Chang Feng‐Chih
Published: February 2004

The miscibility behaviour and hydrogen‐bonding interaction in blends of poly(2‐hydroxypropyl methacrylate) (PHPMA) with polyvinylpyrrolidone (PVP) were characterized using differential scanning calorimetry and Fourier‐transform infrared spectra. This polymer blend was miscible over the whole composition range and an unusually large positive deviation of Tg from the linearity rule was observed, indicating strong hydrogen bonding between the hydroxyl group of PHPMA and the carbonyl group of PVP. Infrared spectroscopic analysis provided positive evidence for the intra‐molecular hydrogen bonding of PHPMA and inter‐molecular hydrogen bonding between PHPMA and PVP at various compositions and temperatures. Furthermore, equilibrium constants and enthalpies of self‐association and inter‐association between functional groups in the blend of PHPMA and PVP were calculated to explain the results. Copyright © 2004 Society of Chemical Industry
A water‐dispersible conducting nanocomposite from suspension polymerisation of thiophene in presence of N‐vinylcarbazole
Authors: Ballav Nirmalya , Biswas Mukul
Published: February 2004

The polymerisation of a mixture of thiophene and N‐vinylcarbazole was achieved in aqueous suspension in the presence of nanodimensional alumina and FeCl3 as oxidant. The resultant composite was found to contain both polythiophene (PTP) and poly(N‐vinylcarbazole) (PNVC) components even after reflux in benzene, which would remove any PNVC homopolymer. The presence of the individual polymer components was endorsed by FTIR spectroscopic analyses. Thermogravimetric analyses showed that the overall stabilities of the composite and the corresponding homopolymers were in the order: PTP–Al2O3 > PTP > PTP–PNVC–Al2O3 > PNVC. Differential thermal analyses studies showed the manifestation of two different exotherms corresponding to the presence of two different polymeric constituents in the PTP–PNVC–Al2O3 composite. Differential scanning calorimetry studies revealed two glass‐transition temperatures (Tg) suggesting the presence of two polymeric moieties in the PTP–PNVC composite. Scanning electron micrographs of the PTP–Al2O3 and PTP–PNVC–Al2O3 composites showed distinctive morphological patterns. Transmission electron microscopic images of the composite revealed that the average particle size varied between 20 and 80 nm. DC conductivities of the composites were of the order of 10−6 S cm−1. Copyright © 2003 Society of Chemical Industry
Study of miscibility enhancement in poly(styrene‐co‐4‐vinylphenol)/poly(ethylene oxide) blends by the spin labelling method
Authors: Tan Li , Chen Shiming , Ping Zhenghua , Shen Yimin
Published: February 2004

The electron spin resonance (ESR) spectra of end‐group spin labelled poly(ethylene oxide) (SLPEO) using 2,2,6,6‐tetramethyl‐piperdine‐1‐oxyl nitroxide and its blends with poly(styrene‐co‐4‐vinylphenol) (STVPhs) of different hydroxyl contents were recorded over a wide temperature range. For a blend of SLPEO and pure polystyrene (PS), the ESR spectrum was composed of a single motion component, indicating that PS was immiscible with PEO. For blends composed of SLPEO and different‐hydroxyl‐content STVPhs, two spectral components with different motion rates were observed over a certain temperature range. The difference between the motion rates should be attributed to micro‐heterogeneity in the blends, with the faster rate corresponding to a nitroxide radical motion trapped in the PEO‐rich domain and the slower rate corresponding to a nitroxide radical motion trapped in the STVPh‐rich domain. Variations in the values of a number of the ESR parameters (Ta, Td and T50G) and the apparent activation energy (Ea) with hydroxyl content in the blends indicated that the miscibility of the blends increased with increasing hydrogen‐bonding density due to specific interactions between the hydroxyl groups in STVPh and the ether oxygens in PEO. Copyright © 2004 Society of Chemical Industry
Analysis of the interfacial interactions in polypropylene/silica nanocomposites
Authors: Rong Min Zhi , Zhang Ming Qiu , Pan Shun Long , Lehmann Björn , Friedrich Klaus
Published: February 2004

Polypropylene‐based composites were prepared by melt blending with nano‐silica, which was pre‐treated by grafting polymerization onto the surface. Tensile moduli and strengths of the composites were determined as a function of the nano‐silica content and the amount of the grafting polymers chemically attached to the nanoparticles, ie percentage grafting. To analyse the relationships between the interfacial interactions in the composites and tensile performance, a number of models dealing with the static and dynamic mechanical behaviours of the particulate composites were applied. It was found that stronger interfacial interactions exist in the grafted nano‐silica‐filled polypropylene composites as compared to the composites with untreated nano‐silica. Since the interfacial interactions occur only within a very short range, the greatest interaction between the modified nanoparticles and the matrix is achieved in the case of low silica concentration and low percentage grafting. An increase in the percentage grafting for various grafted nanoparticles definitely results in an increase of interphase thickness, but the interfacial interactions and the tensile performance of the composites are not necessarily improved because the agglomeration structure of the nanoparticles and the miscibility between the components play the leading role. Copyright © 2004 Society of Chemical Industry
Synthesis of novel poly(vinyl ether)s containing the oxybenzylidenemalononitrile group as a nonlinear optical chromophore, and their electro‐optic properties
Authors: Lee Ju‐Yeon , Lee Won‐Jung , Rhee Bum Ku , Min Hae Sik
Published: February 2004

2,4‐Di‐(2′,2′‐dicyanovinyl)‐1‐(2′‐vinyloxyethoxy)benzene and 2,4‐di‐(2′‐carbomethoxy‐2′‐cyanovinyl)‐1‐(2′‐vinyloxyethoxy)benzene were prepared by condensation of 4‐(2′‐vinyloxyethoxy)isophthaldehyde with malononitrile and methyl cyanoacetate, respectively. The two vinyl monomers were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ether)s containing two oxybenzylidenemalononitrile and oxybenzylidenecyanoacetate groups, which are effective chromophores for second‐order nonlinear optical applications. These polymers were soluble in common organic solvents such as acetone and dimethyl sulforide. They showed thermal stabilities up to 300 °C from thermogravimetric analysis (TGA), with differential scanning calorimeter (DSC) thermograms giving Tg values in the range 73–87 °C. The second harmonic generation (SHG) coefficients (d33) of poled polymer films were around 1.8 × 10−9 esu, and these polymers showed good long‐term thermal stability for 60 days at room temperature, which is acceptable for nonlinear optical (NLO) device applications. Copyright © 2004 Society of Chemical Industry
Preparation and characterization of poly(vinyl chloride)/organoclay nanocomposites by in situ intercalation
Authors: Haiyan Hu , Mingwang Pan , Xiucuo Li , Xudong Shi , Liucheng Zhang
Published: February 2004

In this article, poly(vinyl chloride) (PVC)–organoclay nanocomposites were prepared via in situ polymerization intercalation and melt blending intercalation, respectively. Their nanostructures were characterized by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Differences in the morphologies of the PVC hybrids prepared by in situ intercalation and melt intercalation were investigated. In addition, three kinds of organoclay were used, in order to consider the effect of the interlayer environment on intercalation. The results show that ammonium cations have a great influence on the hybrids prepared by melt intercalation, while they have no obvious effect on the nanostructures of the composites produced via in situ intercalation due to its distinctive process and its mechanism. Copyright © 2004 Society of Chemical Industry
Synthesis of well‐defined comb‐like amphiphilic copolymers with protonizable units in the pendent chains: 2. Poly(2‐(dimethylamino)ethyl methacrylate) grafted poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) copolymers and their association behavior in aqueous solution
Authors: Jin Lan , Liu Ping , Hu Jianhua , Wang Changchun
Published: February 2004

Narrow‐distribution, well‐defined comb‐like amphiphilic copolymers are reported in this work. The copolymers are composed of poly(methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) (P(MMA‐co‐HEMA)) as the backbones and poly(2‐(dimethylamino)ethyl methacrylate) (PDMAEMA) as the grafted chains, with the copolymer backbones being synthesized via atom‐transfer radical polymerization (ATRP) and the grafted chains by oxyanionic polymerization. The copolymers were characterized by gel permeation chromatography (GPC), Fourier‐transform infrared (FT‐IR) spectroscopy and 1H NMR spectroscopy. The aggregation behavior in aqueous solutions of the comb‐like amphiphilic copolymers was also investigated. 1H NMR spectroscopic and surface tension measurements all indicated that the copolymers could form micelles in aqueous solutions and they possessed high surface activity. The results of dynamic light scattering (DLS) and scanning electron microscopy (SEM) investigations showed that the hydrodynamic diameters of the comb‐like amphiphilic copolymer aggregates increased with dilution. Because of the protonizable properties of the graft chains, the surface activity properties and micellar state can be easily modulated by variations in pH. Copyright © 2004 Society of Chemical Industry
Synthesis of well‐defined comb‐like amphiphilic copolymers with protonizable units in the pendent chains: 1. Preparation of narrow polydispersity copolymers of methyl methacrylate and 2‐hydroxyethyl methacrylate by atom‐transfer radical polymerization
Authors: Liu Ping , Jin Lan , Hu Jianhua , Wang Changchun
Published: February 2004

Well‐defined methyl methacrylate (MMA) and 2‐(trimethylsiloxy)ethyl methacrylate (Pro‐HEMA) copolymers were prepared by atom‐transfer radical polymerization(ATRP), using CuCl/2,2′‐bipyridine as catalytic system and p‐toluenesulfonyl chloride as initiator. ATRP process of MMA and Pro‐HEMA was monitored by 1H NMR, and the kinetic curves of the MMA/Pro‐HEMA copolymerization were plotted in terms of the 1H NMR data. At low content of Pro‐HEMA in the feed composition, the copolymerization can be well controlled with the molecular weight, polydispersity and the monomer distribution in the copolymer chain. With the increase of Pro‐HEMA content in the feed mixture, the composition of the final copolymer deviates from the composition of the feed mixture gradually, and gradient copolymers of MMA/Pro‐HEMA can be obtained. Through the hydrolysis process, well‐defined copolymers of MMA/HEMA were obtained from poly(MMA/Pro‐HEMA). Copyright © 2003 Society of Chemical Industry
Kinetics of dehydration–polymerization of aspartic acid and synthesis of polyaspartate catalyzed by potassium bisulfate
Authors: Wang Yaquan , Hou Yongjiang , Zhang Jing , Ruan Gang
Published: February 2004

The dehydration–polymerization kinetics of DL‐ and L‐aspartic acid, either in the absence or presence of KHSO4, from 323 to 573 K, was studied by thermogravimetric analysis (TGA), and the synthesis of polyaspartate through the polymerization of L‐aspartic acid was investigated by a thin‐layer polymerization method. The TGA results revealed that the dehydration–polymerization of both type of aspartic acids proceeds in two steps: first, the loss of one water molecule through the reaction of an amino group of one aspartic acid molecule and a hydroxyl group of another aspartic acid molecule, forming amide bonds, and secondly, the loss of another water molecule through the amide hydrogen and another hydroxyl group, leading to the formation of a succinimide ring. The kinetic parameters of the extrapolated onset temperatures of dehydration—the first and the second maxima—were obtained by a method similar to that of Ozawa–Flynn–Wall. The kinetic results indicate that the dehydration of L‐aspartic acid is slightly more difficult than for DL‐aspartic acid, and that the presence of potassium bisulfate effectively catalyzes the dehydration–polymerization of aspartic acid. In the synthesis of polyaspartate, the product with a weight‐average molecular mass (Mw) of 5000 g mol−1 was obtained in the absence of catalyst. However, in the presence of potassium bisulfate, the products obtained had Mws of up to 7000 g mol−1 Copyright © 2003 Society of Chemical Industry
Evaluation of cross‐linking after accelerated photo‐ageing of silicone rubber
Authors: Virlogeux Fabien , Bianchini David , Delor‐Jestin Florence , Baba Mohamed , Lacoste Jacques
Published: February 2004

Silicone formulations based on polydimethylsiloxane (PDMS) were investigated by using a number of analytical techniques. Horizontal attenuated total reflectance Fourier‐transform infrared (HATR‐FTIR) spectroscopy studies have confirmed the stability of these materials towards photo‐oxidation. No significant oxygenated products were detected after 5000 h of accelerated photo‐ageing. However, by using thermoporosimetry, hardness measurements and densitometry, an important vulnerability of these formulations towards the cross‐linking reactions provoked by UV visible radiation was identified. Thermoporosimetry, using the solid‐solid cyclohexane transition as a textural probe, was also used to visualize the profile of cross‐linking inside the materials by calculation of the mesh size distribution in successive slices of 40 µm in thickness. Copyright © 2003 Society of Chemical Industry
Surface‐initiated atom transfer radical polymerization (ATRP) of styrene from silica nanoparticles under UV irradiation
Authors: Liu Peng , Tian Jun , Liu Weimin , Xue Qunji
Published: February 2004

Diethyldithiocarbamyl‐modified silica nanoparticles were prepared and used as macroinitiator for the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of styrene under UV irradiation. Well‐defined polymer chains were grown from the nanoparticle surfaces to yield particles composed of a silica core and a well‐defined, densely grafted outer PS layer with a mass ratio of styrene to silica, or percentage grafting, of 276.3% after an UV irradiation time of 5 h. Copyright © 2004 Society of Chemical Industry
Influence of the conformational order of glassy isotactic polypropylene on its crystallization and melting behaviour
Authors: Chen Liang , Wang Yanping , Zhu Xinyuan , Yan Deyue
Published: February 2004

The influence of conformational order of glassy isotactic polypropylene (iPP) on its crystallization and melting behaviour was studied by wide‐angle X‐ray diffraction (WAXD), Fourier‐transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The glassy iPP samples with various conformational orders were prepared by freeze‐drying procedure from very dilute solution. WAXD and FTIR results suggest that although freeze‐dried samples are non‐crystalline, their conformational order is rather high and increases with decreasing concentration of parent solutions. With increasing conformational order of glassy samples, the cold crystallization peak shifts to lower temperature, indicating acceleration of crystallization. At low fusion temperature, the conformational order of melt obtained from freeze‐dried samples is high so that the relaxation time of single‐ and pauci‐chains to re‐entangle is long and the interpenetration between single‐ and pauci‐chain collective particles is slow. However, at high fusion temperature, the interpenetration process can be completed very quickly. Copyright © 2004 Society of Chemical Industry
Adsorption of VO2+ by poly[(tetrafluoroethylene)‐co‐(perfluorovinyl ether)] copolymer grafted with acrylic acid using γ‐irradiation
Authors: El‐Sawy Naeem M
Published: February 2004

Grafted films were prepared by the reaction of acrylic acid (AAc) onto poly[(tetrafluoroethylene)‐co‐(perfluorovinyl ether)] copolymer (PFA) using γ‐irradiation by the mutual technique. The grafted copolymer was complexed with the vanadyl group, VO2+, in aqueous solution. The grafted copolymer–metal complexes were examined by infrared and ultraviolet spectrometry, energy‐dispersive spectroscopy (EDS) and X‐ray diffraction (XRD). The amount of vanadium in the grafted films was estimated using EDS. The thermal stability of the films was investigated through thermogravimetric and differential scanning calorimetry measurements. The degree of crystallinity of the grafted and complexed films decreased by treatment with VO2+ ions and also by heating at 300 °C. When heated at a temperature above 300 °C, the grafted chains degraded till they disappeared and the original polymer was almost completely separated. XRD investigation revealed that the metal oxide may be formed as a separate phase with subsequent decrease in the crystallinity of the copolymer. Furthermore, scanning electron microscope (SEM) investigation of the grafted and modified films, both unheated and heated (300 °C), showed changes in the structure and morphology. The tendency of the graft copolymer to adsorb and/or bind to VO2+ from aqueous solution is of promising use in the field of waste treatment of rare metals in the environment. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of novel optically active poly(imide–urethane)s derived from N,N′‐(pyromellitoyl)‐bis‐(L‐leucine) diisocyanate and aromatic diols
Authors: Mallakpour Shadpour , Shahmohammadi Mohammad Hassan
Published: February 2004

N,N′‐(Pyromellitoyl)‐bis‐(L‐leucine) diacid was reacted with ethyl chloroformate in the presence of triethylamine followed by reaction with activated sodium azide and gave N,N′‐(pyromellitoyl)‐bis‐(L‐leucine) diacylazide in high yield. This diacylazide was heated in dry benzene and gave the unstable N,N′‐(pyromellitoyl)‐bis‐(L‐leucine) diisocyanate (5) in quantitative yield. Thus, diisocyanate 5 was generated in situ and polycondensation reaction of this monomer with several aromatic diols, such as 4,4′‐dihydroxybiphenyl, 1,4‐hydroquinone, bisphenol A, phenolphthalein and 1,4‐dihydroxyanthraquinone, was performed in dry toluene under refluxing in the presence of 1,4‐diazabicyclo[2.2.2]octane (triethylenediamine) as a catalyst. The polymerization reactions proceeded within 48 h, producing a series of optically active poly(imide–urethane)s with good yield and moderate inherent viscosity in the range 0.18–0.28 dl g−1. All of the above polymers were fully characterized by infrared spectra, elemental analyses and specific rotation. Some structural characterization and physical properties of these optically active poly(imide–urethane)s are reported Copyright © 2003 Society of Chemical Industry
Polysiloxanes containing crosslinkable diacetylene units in the main chain
Authors: Boileau Sylvie , Bouteiller Laurent , Kowalewska Anna
Published: February 2004

The oxidative coupling of telechelic [2‐(propyn‐1)oxyethyl]oxypropyl‐terminated polydimethylsiloxanes, with the use of copper (I) chloride/TMEDA complex as the coupling catalyst, is described. The results of the studies on the influence of the reaction parameters (the catalyst concentration, the oxygen flow‐rate and the nature of the solvent) are presented. UV curing of the polymers obtained in the course of the oxidative coupling is reported Copyright © 2003 Society of Chemical Industry
Optical properties of plasticized polycarbonate
Authors: Suvorova Anna I , Tchirkova Elena I
Published: February 2004

Optical properties of polycarbonate plasticized by pentaerythritol tris(1,1,2,3,3,3‐hexafluoropropyl) ether (HFP), diheptadecyl‐o‐phthalate and pentaerythrityl tetrabenzoate (TBP) have been determined at wavelengths from 300 to 700 nm. X‐ray diffraction analysis, which was used to examine the polymer structure, showed that all the plasticized systems were amorphous. HFP and, especially, TBP impeded crystallization of the polymer. Plasticized polycarbonate films remained transparent over long periods of time even if they were heated at a temperature higher than the polymer glass transition temperature.

© 2003 Society of Chemical Industry
New liquid‐crystalline poly(ester amide)s: The role of nitro groups in the phase behavior
Authors: Sandhya K. Y. , Pillai C. K. S. , Sree Kumar K.
Published: February 2004

New hydrogen‐bonded liquid‐crystalline poly(ester amide)s (PEA)s were obtained from 1,4‐terephthaloyl[bis‐(3‐nitro‐N‐anthranilic acid)] (5) or 1,4‐terephthaloyl[bis‐(N‐anthranilic acid)] (6), with or without nitro groups, respectively, through the separate condensation of each with hydroquinone or dihydroxynaphthalene. The dicarboxylic monomers were synthesized from 2‐aminobenzoic acid. The phase behavior of the monomers and polymers were studied with differential scanning calorimetry, polarized light microscopy, and wide‐angle X‐ray diffraction methods. Monomer 5, containing nitro groups, exhibited a smectic liquid‐crystalline phase, whereas the texture of monomer 6 without nitro groups appeared to be nematic. The PEAs containing nitro groups exhibited polymorphism (smectic and nematic), whereas those without nitro groups exhibited only one phase transition (a nematic threaded texture). The changes occurring in the phase behavior of the polymers were explained by the introduction of nitro groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1289–1298, 2004
Extension of the chain‐end, free‐volume theory for predicting glass temperature as a function of conversion in hyperbranched polymers obtained through one‐pot approaches
Authors: Liu Hewen , Wilén Carl‐Eric
Published: February 2004

Compared with linear polymers, more factors may affect the glass‐transition temperature (Tg) of a hyperbranched structure, for instance, the contents of end groups, the chemical properties of end groups, branching junctions, and the compactness of a hyperbranched structure. Tg's decrease with increasing content of end‐group free volumes, whereas they increase with increasing polarity of end groups, junction density, or compactness of a hyperbranched structure. However, end‐group free volumes are often a prevailing factor according to the literature. In this work, chain‐end, free‐volume theory was extended for predicting the relations of Tg to conversion (X) and molecular weight (M) in hyperbranched polymers obtained through one‐pot approaches of either polycondensation or self‐condensing vinyl polymerization. The theoretical relations of polymerization degrees to monomer conversions in developing processes of hyperbranched structures reported in the literature were applied in the extended model, and some interesting results were obtained. Tg's of hyperbranched polymers showed a nonlinear relation to reciprocal molecular weight, which differed from the linear relation observed in linear polymers. Tg values decreased with increasing molecular weight in the low‐molecular‐weight range; however, they increased with increasing molecular weight in the high‐molecular‐weight range. Tg values decreased with increasing log M and then turned to a constant value in the high‐molecular‐weight range. The plot of Tg versus 1/M or log M for hyperbranched polymers may exhibit intersecting straight‐line behaviors. The intersection or transition does not result from entanglements that account for such intersections in linear polymers but from a nonlinear feature in hyperbranched polymers according to chain‐end, free‐volume theory. However, the conclusions obtained in this work cannot be extended to dendrimers because after the third generation, the end‐group extents of a dendrimer decrease with molecular weight. Thus, it is very possible for a dendrimer that Tg increases with 1/M before the third generation; however, it decreases with 1/M after the third generation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1235–1242, 2004