bluuebunny/crossref_metadata_2025 huggingface dataset:
Is there a relationship between Wolfram syndrome carrier status and suicide?
Authors: Crawford Joanna , Zielinski Marta A. , Fisher Laura J. , Sutherland Grant R. , Goldney Robert D.
Published: August 2002

Wolfram syndrome (WFS) is a rare, autosomal recessive neurodegenerative disorder. An increased risk of psychiatric disorders and suicide has been reported for heterozygote carriers. In this study we investigated whether mutations in the WFS gene are associated with suicide in the general population. The gene for WFS (WFS1) has recently been mapped to chromosome 4p16.1, and its genomic structure has been characterized. We screened the entire WFS1 ORF in a panel of 100 completed suicides, 60 blood donors not known to have psychiatric illness, and 100 donors with a negative history of depression or suicidal behavior. We did not find evidence of an increased incidence of WFS carriers in the suicide panel and concluded that WFS1 carrier status is not a significant contributor to suicide in the general population. Screening of this highly polymorphic gene resulted in the detection of 33 variants, 13 of which cause amino acid changes. Seven of these changes have not been previously reported and six were unique to our suicide panel. © 2002 Wiley‐Liss, Inc.
Refinement of the genomic structure of STX1A and mutation analysis in nondeletion Williams syndrome patients
Authors: Wu Yuan‐Qing , Bejjani Bassem A. , Tsui Lap‐Chee , Mandel Ariane , Osborne Lucy R. , Shaffer Lisa G.
Published: August 2002

Williams syndrome (WS) is a contiguous gene deletion disorder in which the commonly deleted region contains at least 17 genes. One of these genes, Syntaxin 1A (STX1A), codes for a protein that is highly expressed in the nervous system and is essential for the docking of synaptic vesicles with the presynaptic plasma membrane. In this study, we refine the complete genomic structure of the human STX1A gene by direct sequencing and primer walking of bacterial artificial chromosome (BAC) clones and show that STX1A contains at least 10 exons and 9 introns. The length of exons range from 27 bp to 138 bp and all splice sites conform to the GT‐AG rule. Investigation of the STX1A gene sequence in five WS patients without detectable deletions did not identify any point mutations. Although the regulatory elements that control STX1A transcription were not examined, these results do not support a role for STX1A in the WS phenotype. © 2002 Wiley‐Liss, Inc.
Two cases with partial trisomy 9p: Molecular cytogenetic characterization and clinical follow‐up
Authors: Littooij Annemieke S. , Hochstenbach Ron , Sinke Richard J. , van Tintelen Peter , Giltay Jacques C.
Published: August 2002

This paper describes two patients with partial trisomy 9p and partial trisomy 14q due to 3:1 segregation from de novo maternal reciprocal translocations. The breakpoints are different from previously described 9;14 translocations and their 3:1 segregation products. The clinical phenotype of both cases is compatible with the partial trisomy 9p syndrome. We present the follow‐up of both patients from birth up to age 7 years. Partial trisomy 9p is a frequently described chromosome abnormality. This does not appear to be related to a breakage sensitive locus on chromosome 9p, since the trisomic fragments of the published cases are heterogeneous. In the two cases described here, GTG‐banded karyotyping suggested that the 9p breakpoints were similar; DNA marker analysis, however, showed them to be different. Such DNA studies will be necessary to define the genotype‐phenotype relation in partial trisomy 9p syndrome. © 2002 Wiley‐Liss, Inc.
Paternal age and sporadic schizophrenia: Evidence for de novo mutations
Authors: Malaspina Dolores , Corcoran Cheryl , Fahim Cherine , Berman Ariela , Harkavy‐Friedman Jill , Yale Scott , Goetz Deborah , Goetz Raymond , Harlap Susan , Gorman Jack
Published: August 2002

Schizophrenia is an etiologically heterogeneous syndrome. It has a strong genetic component and exists in clinically indistinguishable familial and nonfamilial (sporadic) forms. A significant role for de novo genetic mutations in genetic schizophrenia vulnerability is suggested by a strong monotonic increase in schizophrenia risk with advancing paternal age. However, an alternative explanation for the paternal age effect in schizophrenia is that childbearing is delayed in fathers who themselves have genetic schizophrenia vulnerability. In this study, we compared paternal birth ages between patient groups with familial (n = 35) and sporadic (n = 68) patients with DSM‐IV schizophrenia from an inpatient schizophrenia research unit. If later age of fathering children is related to having some genetic schizophrenia vulnerability, then paternal birth age should be later in familial schizophrenia cases than in sporadic cases, and any association of father's age and schizophrenia risk in offspring would be a spurious finding, unrelated to etiology. However, if de novo mutations cause sporadic schizophrenia, then patients without a family history of schizophrenia would have older fathers than familial patients. We found that patients without a family history of schizophrenia had significantly older fathers (4.7 years) than familial patients; so later childbirth was not attributable to parental psychiatric illness. These findings support the hypothesis that de novo mutations contribute to the risk for sporadic schizophrenia. © 2002 Wiley‐Liss, Inc.
Primate molar crown formation times and life history evolution revisited
Authors: Macho Gabriele A.
Published: August 2002

Comparative studies have convincingly demonstrated that the pattern and timing of tooth emergence are highly correlated with life‐history variables and brain size. Conversely, a firm relationship between molar formation time and life‐history variables has not yet been established. It seems counterintuitive that one aspect of dental development should be correlated with life‐history variables, whereas the other should not. In order to shed light on this apparent discrepancy this study analyzed all data on primate molar crown formations available in the published literature in relation to life‐history variables, brain size, and female body mass. Crown formation times were found to be particularly highly correlated with both female body mass and brain size. Species that depart from the overall brain/body allometry by being relatively large‐bodied, e.g., Gorilla gorilla and later Theropithecus oswaldi, also have shorter molar crown formation times than expected. The reverse is not found for species that depart from the overall brain/body allometry due to their larger brains, i.e., Homo sapiens. This finding is interpreted within an evolutionary and ecological framework. Specifically, by focusing on ecological commonalities, a scenario is proposed which may allow predictions to be made about the evolutionary history of other extinct primates also. If confirmed in future studies, crown formation time may again become a powerful tool in evolutionary enquiry. Am. J. Primatol. 55:189–201, 2001. © 2001 Wiley‐Liss, Inc.
Ranging pattern and use of space in a group of red howler monkeys (Alouatta seniculus) in a southeastern Colombian rainforest
Authors: Palacios Erwin , Rodriguez Adriana
Published: August 2002

We studied a group of red howler monkeys (Alouatta seniculus) bordering a lake in an eastern Colombian Amazon rainforest for 10 months. The group used an area of 182 ha located mainly on Pleistocene terrace forest and had no overlap with other howler home ranges. Home range use varied through the year as a consequence of fruit and leaf abundance. For example, during the fruit scarcity season the group used an area of flooded forest nearly exclusively, indicating that at least for a portion of the year they are habitat specialists. Two areas intensively used by the group were identified, representing 17.6 % of the home range, and within which 56.9 % of the feeding trees were located. Overall density of feeding trees within the group‘s home range was very low (1.12 trees/ha). Home range size, as well as mean length of daily ranges (1,150 m), is the largest reported for this species to date, and it is likely a consequence of the diminished productivity of the plant communities on poor soil. Our results give an interesting example of the ranging behavior of this primate, which clearly differs from previous descriptions of red howlers. Am. J. Primatol. 55:233–251, 2001. © 2001 Wiley‐Liss, Inc.
In vivo gene therapy for pyridoxine‐induced neuropathy by herpes simplex virus‐mediated gene transfer of neurotrophin‐3
Authors: Chattopadhyay Munmun , Wolfe Darren , Huang Shaohua , Goss James , Glorioso Joseph C. , Mata Marina , Fink David J.
Published: August 2002

Neurotrophic factors have been demonstrated to prevent the development of peripheral neuropathy in animal models, but the therapeutic use of these factors in human disease has been limited by the short serum half‐life and dose‐limiting side effects of these potent peptides. We used peripheral subcutaneous inoculation with a replication‐incompetent, genomic herpes simplex virus‐based vector containing the coding sequence for neurotrophin‐3 to transduce sensory neurons of the rat dorsal root ganglion in vivo, and found that expression of neurotrophin‐3 from the vector protected peripheral sensory axons from neuropathy induced by intoxication with pyridoxine assessed by electrophysiological (foot sensory response amplitude, and conduction velocity, and H‐wave), histological (nerve morphology and morphometry), and behavioral measures of proprioceptive function. In vivo gene transfer using herpes simplex virus vectors provides a unique option for treatment of diseases of the sensory peripheral nervous system.
Nuclear factor‐κB as a molecular target for migraine therapy
Authors: Reuter Uwe , Chiarugi Alberto , Bolay Hayrunnisa , Moskowitz Michael A.
Published: August 2002

Nitric oxide (NO) generated from inducible NO synthase (iNOS) participates in immune and inflammatory responses in many tissues. The NO donor glyceryl trinitrate (GTN) provokes delayed migraine attacks when infused into migraineurs and also causes iNOS expression and delayed inflammation within rodent dura mater. Sodium nitroprusside, an NO donor as well, also increases iNOS expression. Because inflammation and iNOS are potential therapeutic targets, we examined transcriptional regulation of iNOS following GTN infusion and the consequences of its inhibition within dura mater. We show that intravenous GTN increases NO production within macrophages. L‐N(6)‐(1‐iminoethyl)lysine, a selective iNOS inhibitor, attenuates the NO signal, emphasizing the importance of enzymatic activity to delayed NO production. iNOS expression is preceded by significant nuclear factor kappa B (NF‐κB) activity, as reflected by a reduction in the inhibitory protein‐κ‐Bα (IκBα) and activation of NF‐κB after GTN infusion. IκBα degradation, NF‐κB activation, and iNOS expression were attenuated by parthenolide (3mg/kg), the active constituent of feverfew, an anti‐inflammatory drug used for migraine treatment. These findings suggest that GTN promotes NF‐κB activity and inflammation with a time course consistent with migraine attacks in susceptible individuals. We conclude, based on results with this animal model, that blockade of NF‐κB activity provides a novel transcriptional target for the development of anti‐migraine drugs.
Microarray analysis of hippocampal gene expression in global cerebral ischemia
Authors: Jin Kunlin , Mao Xiao Ou , Eshoo Mark W. , Nagayama Tetsuya , Minami Manabu , Simon Roger P. , Greenberg David A.
Published: August 2002

The brain's response to ischemia, which helps determine clinical outcome after stroke, is regulated partly by competing genetic programs that respectively promote cell survival and delayed cell death. Many genes involved in this response have been identified individually or systematically, providing insights into the molecular basis of ischemic injury and potential targets for therapy. The development of microarray systems for gene expression profiling permits screening of large numbers of genes for possible involvement in biological or pathological processes. Therefore, we used an oligodeoxynucleotide‐based microarray consisting of 374 human genes, most implicated previously in apoptosis or related events, to detect alterations in gene expression in the hippocampus of rats subjected to 15 minutes of global cerebral ischemia followed by up to 72 hours of reperfusion. We found 1.7‐fold or greater increases in the expression of 57 genes and 1.7‐fold or greater decreases in the expression of 34 genes at 4, 24, or 72 hours after ischemia. The number of induced genes increased from 4 to 72 hours, whereas the number of repressed genes decreased. The induced genes included genes involved in protein synthesis, genes mutated in hereditary human diseases, proapoptotic genes, antiapoptotic genes, injury‐response genes, receptors, ion channels, and enzymes. We detected transcriptional induction of several genes implicated previously in cerebral ischemia, including ALG2, APP, CASP3, CLU, ERCC3, GADD34, GADD153, IGFBP2, TIAR, VEGF, and VIM, as well as other genes not so implicated. We also found coinduction of several groups of related genes that might represent functional modules within the ischemic neuronal transcriptome, including VEGF and its receptor, NRP1; the IGF1 receptor and the IGF1‐binding protein IGFBP2; Rb, the Rb‐binding protein E2F1, and the E2F‐related transcription factor, TFDP1; the CACNB3 and CACNB4 β‐subunits of the voltage‐gated calcium channel; and caspase‐3 and its substrates, ACINUS, FEM1, and GSN. To test the hypothesis that genes identified through this approach might have roles in the pathophysiology of cerebral ischemia, we measured expression of the products of two induced genes not heretofore implicated in cerebral ischemia—GRB2, an adapter protein involved in growth‐factor signaling pathways, and SMN1, which participates in RNA processing and is deleted in most cases of spinal muscular atrophy. Western analysis showed enhanced expression of both proteins in hippocampus at 24 to 72 hours after ischemia, and SMN1 was localized by immunohistochemistry to hippocampal neurons. These results suggest that microarray analysis of gene expression may be useful for elucidating novel molecular mediators of cell death and survival in the ischemic brain.
Metabolism of dimethylarsinic acid in rats: production of unidentified metabolites in vivo
Authors: Yoshida Kaoru , Kuroda Koichi , Inoue Yoshinori , Chen Hua , Date Yukiko , Wanibuchi Hideki , Fukushima Shoji , Endo Ginji
Published: August 2002

Our previous study revealed that two unidentified metabolites, M‐1 and M‐2, were excreted in urine after long‐term oral administration of dimethylarsinic acid (DMA), the main metabolite of inorganic arsenic. In the present study, we attempted to clarify the mechanism of production of these unknown metabolites. Male F344/DuCrj rats were administered a single dose of DMA (50 mg kg−1) orally or intraperitoneally with or without pretreatment with L‐buthionine‐SR‐sulfoximine (BSO), which inhibits glutathione (GSH) synthesis. Urine was collected by forced urination at various time points after administration of DMA. Arsenic metabolites in urine were analyzed by ion chromatography with inductively coupled plasma mass spectrometry (IC–ICP‐MS). The unidentified metabolites M‐1 and M‐2 were excreted later than elimination of DMA and trimethylarsine oxide (TMAO). GSH depletion decreased in TMAO elimination, suggesting that GSH plays important roles in the methylation of DMA to TMAO in rats. There was no difference in the amount of production of either M‐1 or M‐2 between BSO‐pretreated rats and controls, suggesting that M‐1 and M‐2 cannot be formed during methylation in the liver. The amounts of elimination of M‐1 and M‐2 were less after intraperitoneal administration than after oral administration.

Male F344/DuCrj rats were given 100 mg As l−1 DMA via drinking water for 20 weeks. Urine and feces were collected forcibly and were analyzed by IC–ICP‐MS. A new unidentified metabolite, M‐3, was detected only in feces as a metabolite of DMA after 20 weeks exposure to DMA, although M‐1 and M‐2 were found in both urine and feces. The unidentified metabolites M‐1, M‐2, and M‐3 were excreted mainly as fecal metabolites along with unmetabolized DMA. This finding also suggests that M‐1, M‐2, and M‐3 might be produced in the intestinal tract. Copyright © 2001 John Wiley & Sons, Ltd.
Toxic effect of triphenyltin chloride on the alga Spirulina subsalsa
Authors: Huang Guolan , Song Zhihui , Liu Guangliang , Zhang Weihua
Published: August 2002

A previous study on the deleterious effect of triphenyltin chloride (TPTCl) on the alga Spirulina subsalsa reported on four physiological and biochemical indices (or parameters): growth rate, chlorophyll content, phycocyanin content and nitrate reductase activity. In the present study, further research was performed to confirm the findings reported in the previous paper, using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SEM images show significant changes in the screw‐pitch of S. subsalsa, suggesting that TPTCl may damage the inheritance characteristics of S. subsalsa. The TEM images illustrate that the external pectin theca, limiting membrane and inter photosynthetically active lamella in the S. subsalsa cell are those targets that can be easily damaged. Reversible and irreversible cell damage (cell necrosis) are also observed. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of novel poly(amide imide)s based on bis(p‐amidobenzoic acid)‐n‐trimellitylimido‐L‐leucine
Authors: Mallakpour Shadpour E. , Hajipour Abdol‐Reza , Vahabi Ramin
Published: August 2002

N‐Trimellitylimido‐L‐leucine was reacted with thionyl chloride, and N‐trimellitylimido‐L‐leucine diacid chloride was obtained in a quantitative yield. The reaction of this diacid chloride with p‐aminobenzoic acid was performed in dry tetrahydrofuran, and bis(p‐amidobenzoic acid)‐N‐trimellitylimido‐L‐leucine (5) was obtained as a novel optically active aromatic imide–amide diacid monomer in a high yield. The direct polycondensation reaction of the monomer imide–amide diacid 5 with 4,4′‐diaminodiphenylsulfone, 4,4′‐diaminodiphenylether, 1,4‐phenylenediamine, 1,3‐phenylenediamine, 2,4‐diaminotoluene, and benzidine (4,4′‐diaminobiphenyl) was carried out in a medium consisting of triphenyl phosphite, N‐methyl‐2‐pyrolidone, pyridine, and calcium chloride. The resulting novel poly(amide imide)s (PAIs), with inherent viscosities of 0.22–0.52 dL g−1, were obtained in high yields, were optically active, and had moderate thermal stability. All of the compounds were fully characterized with IR spectroscopy, elemental analyses, and specific rotation. Some structural characterization and physical properties of these new optically active PAIs are reported. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 35–43, 2002; DOI 10.1002/app.10181
Ionically conductive polymer gel electrolytes consisting of crosslinked methacrylonitrile and organic electrolyte
Authors: Kubota Naoji , Fujii Shigetada , Tatsumoto Nobuhide , Sano Takayuki
Published: August 2002

To develop a highly ion‐conductive polymer electrolyte, we copolymerized methacrylonitrile (MAN) with ethylene glycol dimethacrylate (EGDMA) in propylene carbonate that contained tetraethylammonium tetrafluoroborate (TEATFB), changing the TEATFB concentration and the MAN/EGDMA molar ratio. We characterized the obtained polymer gel electrolytes with complex impedance analysis and cyclic voltammetry, intending to apply them to electric double‐layer capacitors. The ionic conductivities of the polymer gel electrolytes were dependent on the TEATFB concentration, the temperature, and particularly the crosslinking degree. The polymer gel electrolytes in this system exhibited high room‐temperature conductivities (>10−3 S/cm). Furthermore, these polymer electrolytes showed good electrochemical stability windows ranging from −4.0 to +4.0 V versus Ag. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2655–2659, 2002
Preparation of thermal‐responsive poly(propylene) membranes grafted with n‐isopropylacrylamide by plasma‐induced polymerization and their water permeation
Authors: Kim So Yeon , Kanamori Toshiyuki , Shinbo Toshio
Published: August 2002

Poly(propylene) (PP) membrane grafted with poly(N‐isopropylacrylamide) (PNIPAAm), which is known to have a lower critical solution temperature (LCST) at around 32°C, was prepared by the plasma‐induced graft polymerization technique. Graft polymerization of PNIPAAm onto a PP membrane was confirmed by microscopic attenuated total reflection/Fourier transform IR spectroscopy. The grafting yield of PNIPAAm increased with the concentration of N‐isopropylacrylamide monomer and the reaction time of graft polymerization. The average pore size of the PP membrane also affected the grafting yield. From the field emission scanning electron microscopy (FE‐SEM) measurement, we observed a morphological change in the PP‐g‐PNIPAAm membrane under wet conditions at 25°C below LCST. The permeability of water through the PP‐g‐PNIPAAm membrane was controlled by temperature. The PP‐g‐PNIPAAm membrane (PN05 and PN10) exhibited higher water permeability (Lp) than the original PP substrate membrane below LCST. As the temperature increased to above LCST, Lp gradually decreased. In addition, the graft yield of PNIPAAm and the average pore size of the PP substrate influenced water permeability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1168–1177, 2002; DOI 10.1002/app.10410
Moisture‐sorption characteristics of starch/low‐density polyethylene films
Authors: Raj Baldev , Raj A. Eugene , Kumar K. R. , Siddarramaiah
Published: August 2002

Moisture‐sorption characteristics of starch/low‐density polyethylene (LDPE) blends were carried out at 27°C for water activity (aw) from 0.1 to 0.9. The sorption data were used to fit six different sorption isotherm models proposed in the literature. The model constants were determined by linear fitting of the sorption equations. The ranges of applicability of water activity for the isotherm models reported in the article lies between 0.1 and 0.4 (monomolecular layer) for the BET model and between 0.3 and 0.9 (multimolecular and capillary condensation layers) for other models. The value of the coefficient of determination (R2= 0.97 ± 0.02) confirms the linear fitting of the equations studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1193–1202, 2002; DOI 10.1002/app.10417
Polysiloxane modified epoxy networks. IV. Catalytic effect on fracture behaviors of jointed interpenetrating polymer networks
Authors: Wu Shin‐Yu , Lee Shiao‐Lin , Chang Wen‐Lie , Sung Po‐Hou
Published: August 2002

Jointed interpenetrating polymer networks of epoxy resin and poly(dimethylsiloxane) (PDMS) are synthesized using PDMS‐α,ω ‐diol as the reactive modifier. We attempt to control the reaction rate and the morphology of the rubber domains by using the acid as the catalyst. According to the scanning electron microscopy results, the morphologies of the acid catalyzed specimens do not show strain‐induced crystallization during the fracture mode due to the homogeneity of the molecule structure. The tensile strengths and moduli decrease when the reaction rate is increased. However, the acid contents have no effect on the fracture energy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2352–2357, 2002
Mechanical properties of poly(lactic acid) and wheat starch blends with methylenediphenyl diisocyanate
Authors: Wang Hua , Sun Xiuzhi , Seib Paul
Published: August 2002

Poly(lactic acid) (PLA) and wheat starch are biodegradable polymers derived from renewable sources. A previous study showed that thermally blending starch and PLA in the presence of methylenediphenyl diisocyanate (MDI) enhanced the mechanical properties of the blends. In this work, blends of PLA with various levels of wheat starch and MDI were hot mixed at 180°C then hot‐pressure molded at 175°C to form test specimens. The blends were characterized for mechanical properties, fracture microstructure, and water absorption. Pure PLA had a tensile strength of 62.7 MPa and elongation of 6.5%. The blend with 45% wheat starch and 0.5 wt % MDI gave the highest tensile strength of about 68 MPa with about 5.1% elongation. The blend with 20% starch and 0.5 wt % MDI had the lowest tensile strength of about 58 MPa with about 5.6% elongation. Dynamic mechanical analysis showed that storage modulus increased and tan δ decreased as starch level increased, but almost leveled off when starch level reached 45% or higher. Water absorption of the blends increased significantly with starch content. Yet the blend, if water proofed on its surface, has potential for short‐term disposable applications. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1257–1262, 2002; DOI 10.1002/app.10457
Structure and damping properties of polydimethylsiloxane and polymethacrylate sequential interpenetrating polymer networks
Authors: Huang Guang‐Su , Li Qiang , Jiang Lu‐Xia
Published: August 2002

By using the technology of the sequential interpenetrating polymer network, a series of novel damping materials based on a polydimethylsiloxane (PDMS)/polyacrylate (PAC) matrix with polymethacrylate (PMAC) were synthesized. They have a controllable broad transition peak spanning the temperature range of 150–220°C and the medial value of loss factor with maximum of 0.35–0.60. Dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and atomic force microscopy (AFM) were applied to analyze and characterize the transition behavior and the microphase structure of the materials. It was found that the size and height of a transition peak at both the low‐ and the high‐temperature zones change as a function not only of the concentration of PMAC and PDMS but also of the kind of PMAC; simultaneously, the low‐ temperature behavior was also governed by the crystallization of PDMS. The content of the crosslinking agent exerts a significant influence on the configuration of the curves of the transition peaks. AFM shows a characteristic phase morphology of double‐phase continuity containing a transition layer and domain less than 1 μm, indicating that the interwoven multilayer networks are the key to incorporation of the immiscible components and form a broad damping functional region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 545–551, 2002
Pyrolysis of polymethylsilsesquioxane
Authors: Ma Jun , Shi Lianghe , Shi Yongyxi , Luo Shanguo , Xu Jian
Published: August 2002

Changes of the composition and structure of various samples of polymethylsilsesquioxane (PMSQ), pyrolyzed at different temperatures under flowing nitrogen, were investigated using thermogravimetric analysis, Raman and Fourier transform infrared spectroscopies, X‐ray photoelectron spectroscopy, elemental analysis, scanning electron microscopy, and transmission electron microscopy. The center of the Si2p peak could be used to estimate the extent of the pyrolysis of PMSQ. Two temperature domains correspond to important changes in the chemical composition of PMSQ. The former (Tp < 500°C) is related to the conversion from a regular structure to an irregular structure and the latter (Tp > 500°C) is associated with the organic– ceramic conversion. During the latter pyrolysis, flowing of the molten bulk occurred and then a final solid structure was obtained. The main product of PMSQ, pyrolyzed at 900°C, is silica, as well as some amount of silicon oxycarbide and traces of amorphous carbon. Based on the above analysis and observation, a conversion process from polysilsesquioxane to a ceramic is proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1077–1086, 2002
Effects of hygrothermally decomposed polyurethane on the curing and mechanical properties of carbon black‐filled epoxidized natural rubber vulcanizates
Authors: Mohd Ishak Z. A. , Wan P. Y. , Wong P. L. , Ahmad Z. , Ishiaku U. S. , Karger‐Kocsis J.
Published: August 2002

Hygrothermally decomposed polyurethane (HD‐PUR) was mixed up to 20 phr in epoxidized natural rubber (with 50 mol % epoxidation; ENR50) recipes, and the curing and mechanical behaviors were studied. Mechanical testing of the ENR50/HD‐PUR vulcanizates determined the tensile, tear, compression‐set, hardness, abrasion, hysteresis, and resilience properties. No significant changes were observed in the tensile properties with the incorporation of HD‐PUR. The ENR50 compounds showed an increase in compression set with increasing HD‐PUR content. Rubbers cured by a semi‐efficient vulcanization system gave the best overall performance. A further improvement in curing and mechanical properties was achieved by the carbon black grade N330 being replaced with a more active grade (N375). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2265–2276, 2002
Synthesis and properties of polycarbonate‐poly(methyl methacrylate) graft copolymers by polycondensation of macromonomers
Authors: Okamoto Masaya
Published: August 2002

Polycarbonates (PCs) having poly(methyl methacrylate)s (PMMAs) as graft chains were prepared by the polycondensation of PC oligomers bearing chloroformate groups as the end groups with dicarboxyl‐terminated PMMA macromonomers, which were prepared by the radical polymerization of methyl methacrylate in the presence of thiomalic acid as a chain transfer. The resulting PC‐PMMA graft copolymers were transparent in comparison with PC/PMMA blend polymers, and had higher Vickers hardness than blend polymers when both of them had the same PMMA content. According to the results of multiple regression analysis, the improvement of Vickers hardness was conducive to length (46%) and number (37%) of PMMA branches. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2670–2675, 2001
Glass‐transition and melting behavior of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends
Authors: Shi Yu , Jabarin Saleh A.
Published: August 2002

The glass‐transition temperatures and melting behaviors of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were studied. Two blend systems were used for this work, with PET and PEN of different grades. It was found that Tg increases almost linearly with blend composition. Both the Gibbs–DiMarzio equation and the Fox equation fit experimental data very well, indicating copolymer‐like behavior of the blend systems. Multiple melting peaks were observed for all blend samples as well as for PET and PEN. The equilibrium melting point was obtained using the Hoffman–Weeks method. The melting points of PET and PEN were depressed as a result of the formation of miscible blends and copolymers. The Flory–Huggins theory was used to study the melting‐point depression for the blend system, and the Nishi–Wang equation was used to calculate the interaction parameter (χ12). The calculated χ12 is a small negative number, indicating the formation of thermodynamically stable, miscible blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 11–22, 2001
Solubility of additives: Grafting of itaconic acid onto LDPE by reactive extrusion. II. Effect of stabilizers
Authors: Pesetskii S. S. , Jurkowski B. , Krivoguz Y. M. , Olkhov Y. A.
Published: August 2002

Static and dynamic mixers set on the Brabender plastograph were used to investigate the grafting of itaconic acid (IA) onto low‐density polyethylene (LDPE) by the reactive extrusion. The initiators of free‐radical reactions were monoperoxide 2,5‐dimethyl‐2‐hydroxy‐5‐tert‐butylperoxy‐3‐hexyne and diperoxide 2,5‐dimethyl‐2,5‐di(tert‐butyl peroxy)‐hexane. The reaction mix contained stabilizers of phenolic type as follows: 2,6‐ditert‐butyl‐4‐methyl phenol; ester of 3,5‐ditert‐butyl‐4‐hydroxyphenyl‐propanoic acid and pentaerythritol; 4‐alkoxy‐2‐hydroxy‐benzophenone; and 1,4‐dihydroxybenzene. The effect of stabilizers, which follow the radical mechanism on the grafting of IA and on the crosslinking, depends on their solubility in the polymer and the monomer. The stabilizers (e.g., 1,4‐dihydroxybenzene) with increased affinity toward the monomer reduce the grafting yield and inhibit crosslinking. At 0.3–0.5 wt % of the stabilizer insoluble in the monomer, the grafting yield can be increased, while inhibiting the LDPE‐g‐IA crosslinking, irrespective of the peroxide used. Hence, classical stabilizers can initiate grafting reactions at raised concentrations, temperatures, and application of the shearing stresses. They also help to obtain a high‐grafting yield and a reduced crosslinking degree. A stabilizer, having a close affinity toward LDPE, influences the LDPE‐g‐IA structure. The stabilizer content of 0.5 wt % transforms the topological structure of LDPE‐g‐IA into uniblock. Its molecular weight distribution (MWD) may be narrow (−Mn/−Mw < 2) or broad (−Mn/−Mw > 2), depending on the concentration of the initiator used. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3439–3448, 2001
Rheology of EPR/PP blends
Authors: Mighri F. , Huneault M. A. , Ajji A. , Ko G. H. , Watanabe F.
Published: August 2002

The rheological behavior of polypropylene, PP, ethylene‐propylene copolymer, EPR, and EPR/PP blends was studied. Zero‐shear viscosity and elastic relaxation time were determined by least‐squares fits by using a Carreau–Yasuda model with Arrhenius temperature dependency. The effect of PP and EPR molecular weight, ethylene ratio in EPR copolymer (E/EPR), and EPR concentration on the zero‐shear viscosity and elasticity of EPR/PP blends was determined experimentally. Molecular weight effects are compared to theoretically expected relationships. EPR concentration effect and E/EPR ratio effects agree well with predictions made by using the Tsenoglou model. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2113–2127, 2001
Macrostructural changes in thermally treated viscose fibers due to cold drawing process
Authors: Fouda I. M. , Shabana H. M.
Published: August 2002

The molecular orientation of thermally treated viscose (rayon) fibers was investigated by two techniques. The mechanical parameters, which were obtained by a micro‐stress–strain device in conjunction with an interference microscope, and structural parameters, which gave the optical properties, of boiled viscose fibers for different intervals of time and cold drawn at room temperature were calculated. The changes in the stress and draw ratios were evaluated to obtain the shrinkage factor, uniaxial tension, and true stress and orientation factors 〈P2(cos θ)〉 and 〈P4(cos θ)〉. The functionsf2(θ),f4(θ), andf6(θ) were also calculated. The dielectric constant, dielectric susceptibility, number of moles in physical network chains between entanglements in the semicrystalline phase per unit volume, surface reflectivity, segment anisotropy, number of chains between crosslinks per unit volume, and number of crystals per unit volume were among the evaluated parameters. An empirical formula was suggested to correlate the changes in the evaluated parameters with different draw ratios, and its constants were determined. The study demonstrated changes in the molecular orientation factors and the evaluated macrostructural parameters as a result of applied stress and the boiling effect. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2387–2398, 2001
Role of paper sludge particle size and extrusion temperature on performance of paper sludge–thermoplastic polymer composites
Authors: Son Jungil , Kim Hyun‐Joong , Lee Phil‐Woo
Published: August 2002

The effect of paper sludge's particle size and extrusion temperature on the physical and mechanical properties of paper sludge–thermoplastic polymer composites was investigated. In the experiment three levels of particle sizes for the paper sludge and four extrusion temperatures were designed to examine the physical and mechanical properties of these composites. The ash contents of the paper sludge were about 73.7, 46.2, and 38.1% with particle sizes of below 0.15, 0.18–0.25, and 0.42–0.84 mm, respectively, which meant lower ash content and higher cellulose fiber content, in the larger particle size of paper sludge. As the particle size of the paper sludge decreased, the swelling thickness, water absorption, and tensile and flexural strengths of the composite improved; but the particle size of the paper sludge had no effect on its unnotched impact strength. With the increase of the extrusion temperature the thickness swelling and water absorption of the composites were slightly improved but not statistically different. A rise of the extrusion temperature generally had a positive effect on the tensile and flexural properties of the composite. The notched and unnotched impact strengths of the composite increased with the increase of the extrusion temperature from 190 to 230°C, but they decreased slightly at an extrusion temperature of 250°C. This low impact energy at an extrusion temperature of 250°C may be attributed to the excessively brittle fibers from thermal decomposition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2709–2718, 2001
The synthesis of nonporous poly(isobutyl methacrylate) microspheres by suspension polymerization technique and investigation of their swelling properties
Authors: Bodugöz Hatice , Güven Olgun
Published: August 2002

Poly(isobutyl methacrylate) (PiBMA) microspheres with different crosslinking densities were synthesized by suspension polymerization technique in aqueous medium and their characterization and swelling behaviors in different solvents were investigated. PiBMA spheres with a 800‐ to 1500‐μm‐diameter range were obtained by using benzoyl peroxide (BPO) as polymerization initiator, 1/5 ratio of monomer/water in volume, tricalcium phosphate (TCP), and poly(N vinyl‐2‐pyrrolidone) (PVP) as suspension stabilizer with 350 rpm stirring rate in nitrogen atmosphere. The influence of type and amount of crosslinking agent on the swelling properties and diffusional behavior, diffusion coefficient, and network properties of the spheres were examined in pentane, hexane, heptane, and gasoline. Dynamic swelling behaviors of crosslinked spheres were determined by measuring the diameter of the sphere as a function of time by an optical microscope. Swelling behaviors and network properties were found to be dependent on the diameter, crosslinking density of the sphere, and crosslinking agent and solvent. The results of this study indicate that the crosslinked PiBMA microsphere can be swollen in gasoline very well and retains a high ratio (1500% of its volume) of gasoline in their structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 349–356, 2002
Heat setting
Authors: Gupta V. B.
Published: August 2002

As‐manufactured polymeric fibers are oriented semi‐crystalline structures in which the macromolecules are rarely in their equilibrium state. Further instabilities are imparted when the fibers are converted to yarns and the yarns to fabrics. Heat setting is an important industrial process, since it rids them of their instabilities. This review article first considers aspects that are relevant to the broad area of heat setting, viz., the origin of instability, the durability of set, thermal and dynamic mechanical transitions, thermodynamic basis of setting, shrinkage and shrinkage stress, and characterization of the degree of set. The heat setting of major thermoplastic fibers, viz., polyester, polyamide, polyacrylonitrile, polypropylene, and polyethylene has been described in terms of the conditions of heat setting, the structural and morphological changes that occur on heat setting, and the changes in their physical properties. It is shown that heat setting affects such important properties as stress–strain and recovery behavior, dye‐uptake, optical properties, and thermal properties. The structural and morphological changes have been described in terms of changes in crystallinity, crystal size and their size distribution, crystal defects, crystal orientation, the nature of the amorphous phase and its orientation, the coupling of the crystalline and amorphous phases, etc. The structural basis of property changes is then discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 586–609, 2002
Porous elastomeric beads from crosslinked emulsions
Authors: Dufaud O. , Favre E. , Sadtler V.
Published: August 2002

The production of porous polymeric particles is attractive for a large number of applications and can be achieved by various techniques. Although numerous production schemes exist for glassy polymers, difficulties arise for soft, rubbery materials that need a chemical crosslinking step, such as elastomers. This is particularly true for poly(dimethylsiloxane) (PDMS), which shows the lowest glass‐transition temperature among the polymers. Recent studies suggest in situ hydrogen bubble formation or vacuum drying of water droplets dispersed in the polymer matrix in order to generate porous PDMS structures. In this work we report early results based on the chemical crosslinking of water in PDMS emulsion droplets in a mechanically stirred thermostated water vessel. This approach is shown to lead to high porosity PDMS beads (ca. 10−3 m particle diameter) with an open structure whose properties (diameter and porosity) are strongly influenced by the starting composition (solvent, surfactant, and polymer types and ratios), as well as the operating parameters (agitation and temperature). The possible uses of these derived beads are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 967–971, 2002
High‐solids mar resistant clearcoats prepared from an isophthalate‐based oligoester and a melamine resin. Study and characterization of mar resistance with scanning probe microscopy method
Authors: Diakoumakos Constantinos D. , Jones Frank N. , Ye Huijuan , Shen Weidian C.
Published: August 2002

A new series of high‐solids [low‐VOC (volatile organic compound)content] mar resistant clearcoats (CL‐series) were prepared upon crosslinking of a new‐synthesized hydroxyl‐terminated isophthalate‐based liquid oligoester (L‐311) with an hexakis(methoxymethylol)melamine (HMMM) resin, via an acid‐catalyzed etherification reaction. The chemical, physical, and mechanical properties of the CL‐clearcoats were compared to those of a reference clearcoat (CRO). An attempt was made to investigate the effect that the amounts of catalyst and melamine resin had on the clearcoats' physical, chemical, and mechanical properties, and moreover, to correlate these properties to the films chemical structures. The new‐formulated high‐solids clearcoats (CL‐series) presented enhanced processability and higher NVW values (lower VOC content) than the reference clearcoat CRO, and their properties (pencil hardness, knoop hardness, adhesion, impact resistance, solvent and gasoline resistance, mar resistance, and flexibility) were better or comparable to those of the CRO. More specifically, the mar resistance of the CL‐clearcoats series was investigated by applying both the crockmeter test and a novel method that employed a modified scanning probe microscope. In addition, we identified and characterized the different responses of the CRO and certain CL‐clearcoats to marring stress. The experimental data regarding the mar resistance of the new‐formulated clearcoats fully justified our polymer design strategy, verifying our expectations for the possibility of preparing glossy, high‐solids mar‐resistant clearcoats that could present enhanced processability and solvent resistance, relatively high pencil hardness, and at the same time very good elastic recovery to marring stress. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1317–1333, 2002
Survey of macroalgal mats in the Gulf of Finland, Baltic Sea
Authors: Lehvo Annamaija , Bäck Saara
Published: August 2002

1. The occurrence of macroalgal mats in shallow coastal waters was studied in the Gulf of Finland, Baltic Sea.

2. Altogether, 89 sites were visited and the near‐shore waters of the islands were investigated, mainly by scuba diver, to about 10 m depth. In 26 places, drifting algal mats were recorded.

3. The macroalgal mats occurred in patches of up to 10 m2 in area, in a range of depths from 0.5 to 10 m, with the optimum depth being less than 5 m. The coverage of the mat varied between 10–70%, and the thickness of the mat was found to vary between 2 and 30 cm. The most frequently recorded, dominant species was Cladophora glomerata.

4. In some cases, anoxic conditions were observed as black sediment underneath the mat. This phenomenon could be a sign of very severe eutrophication of the Baltic Sea.

Copyright © 2001 John Wiley & Sons, Ltd.
Angling and conservation at Sites of Special Scientific Interest in England: economics, attitudes and impacts
Authors: Williams Adrian E. , Moss Brian
Published: August 2002

1. An extensive questionnaire (181 questions) was devised to examine the relationships and attitudes of angling clubs to their local environment and conservation organizations. Questions related to the fishery itself and the economics of the club were also asked. The questionnaire was sent to 59 coarse‐angling clubs that fished shallow Sites of Special Scientific Interest (SSSIs) in England. SSSIs are statutorily designated sites of the highest conservation value in Britain. Thirty‐one valid questionnaires were returned.

2. The average cost of leasing a water body was £645 ha−1 year−1 (1997 prices) and an adult angler paid, on average, £67 year−1 to fish at a club. The overall profit made by an angling club in an SSSI was, on average, £1760 year−1. Most clubs were not run on a profit basis. Compensatory cash payments were unlikely to influence attitudes to restrictions on stocking.

3. Angling clubs generally had a positive attitude to nature conservation and its enhancement. In 83% of cases, where stocking restrictions had been introduced by English Nature (the statutory nature conservation organization in England) the club involved agreed with the decision. Only 10% of respondents thought that a close season was detrimental to fishing. Aesthetic qualities and tranquillity were considered very important for a fishery to be successful and these were seen to be consistent with nature conservation values.

4. There were areas of concern. Common carp was the fish most likely to be stocked, largely because of financial benefits. Nonetheless, a trend towards carp stocking may have reached a peak. Management culling of fish such as pike took place at 42% of sites and some clubs believed that stronger ties with environmental groups should not be pursued. It may be some time before certain aspects of fishery management, suggested by English Nature as best conservation practice, are accepted by all angling clubs in SSSIs, but attitudes were found to be more positive than often assumed. Copyright © 2001 John Wiley & Sons, Ltd.