bluuebunny/crossref_metadata_2025 huggingface dataset:
Beta 1 integrin activation mediates adhesive differences between trisomy 21 and non‐trisomic fibroblasts on type VI collagen
Authors: Jongewaard Ian N. , Lauer Ronald M. , Behrendt Douglas A. , Patil Shivanand , Klewer Scott E.
Published: August 2002

Trisomy 21 (Down syndrome) is a common genetic condition with a high incidence of congenital heart defects (CHD), particularly those involving abnormal development of the embryonic atrioventricular (AV) canal. Type VI collagen (Col VI) is expressed in the developing AV canal extracellular matrix, and has been associated with trisomy 21 AV canal defects in human genetic studies. Although the molecular mechanisms linking Col VI and trisomy 21 AV canal defects are not well understood, a computer model predicts increased cell adhesiveness is responsible for these CHD. We compared integrin‐mediated cell adhesive properties for skin fibroblasts isolated from trisomy 21 and non‐trisomic individuals on Col VI, fibronectin (FN) and type I collagen (Col I). Cell lines demonstrate similar adhesion profiles to FN and Col I, but all trisomy 21 cells display increased adhesive capacity for Col VI compared to non‐trisomic fibroblasts. Cell adhesion to type VI collagen was shown to be GRGDS independent, but β1 integrin family dependent. Function‐blocking antibodies identified α3β1 as the predominant integrin mediating trisomy 21 and non‐trisomic skin fibroblast adhesion on Col VI. Trisomy 21 and non‐trisomic fibroblasts display similar expression levels for each of the integrin receptors examined. A β1 integrin‐activating antibody augments non‐trisomic cell adhesion on Col VI, but has no effect upon trisomy 21 fibroblasts. These results demonstrate that β1 integrin family members mediate trisomy 21 and non‐trisomic skin fibroblast adhesion for Col VI. Altered activation state of the β1 integrin is a mechanism responsible for increased trisomy 21 cell adhesion on Col VI. © 2002 Wiley‐Liss, Inc.
Are bonobos (Pan paniscus) really more bipedal than chimpanzees (Pan troglodytes)?
Authors: Videan Elaine N. , McGrew W.C.
Published: August 2002

Of the living apes, the chimpanzee (Pan troglodytes) and bonobo (Pan paniscus) are often presented as possible models for the evolution of hominid bipedalism. Bipedality in matched pairs of captive bonobos and chimpanzees was analyzed to test hypotheses for the evolution of bipedalism, derived from a direct referential model. There was no overall species difference in rates of bipedal positional behavior, either postural or locomotory. The hominoid species differed in the function or use of bipedality, with bonobos showing more bipedality for carrying and vigilance, and chimpanzees showing more bipedality for display. Am. J. Primatol. 54:233–239, 2001. © 2001 Wiley‐Liss, Inc.
Analysis of infant handling and the effects of female rank among Tana River adult female yellow baboons (Papio cynocephalus cynocephalus) using permutation/randomization tests
Authors: Bentley‐Condit Vicki K. , Moore Thomas , Smith E.O.
Published: August 2002

Infant handling has been documented in numerous species. Among cercopithecines, interaction motivations are reported to range from aunting to kidnapping; these interactions are often distressful for both mother and infant. Here we examine handling by adult female yellow baboons (Papio cynocephalus cynocephalus) at the Tana River National Primate Reserve, Kenya, using a relatively new, computer‐intensive statistical approach of permutation/randomization tests to deal with repeated measures effects and a skewed sample. We hypothesized 1) a tendency for handlers to handle the infants of females ranked similarly or lower than themselves, and 2) more successful infant handling by higher‐ranked females, particularly with very young infants. We collected focal data on 23 females (11 mother–infant pairs) over an 11‐mo period, with a total of 303 attempted and/or successful “handles” utilized in the permutation analyses. The general patterns apparent in the data seemed to support our hypotheses. However, the permutation tests showed that while females are somewhat more likely to attempt to handle the infants of females ranked “same or lower” than themselves, lower‐ranked females are able to prevent more than three‐fourths of the attempted interactions, and there is no statistically significant trend for females to successfully handle these infants. Further refinement of the analyses showed no significant tendencies for females to handle those infants ranked “lower” or “immediately lower” than themselves, casting doubt on the significant finding for “same or lower” attempts. Further, there was no significant effect for higher‐ranked females to successfully handle an infant during its first month. Thus, rank does not seem to offer any privileges in terms of handling an infant in this population. We believe the permutation tests are an effective way to analyze repeated measures data and offer a more sensitive analysis tool for determining true significance. Am. J. Primatol. 55:117–130, 2001. © 2001 Wiley‐Liss, Inc.
Maxillary canine‐first premolar transposition in two Native American skeletal samples from New Mexico
Authors: Burnett Scott E. , Weets Jaimin D.
Published: August 2002

Tooth transposition is a rare anomaly in which the position of two adjacent teeth in the dental arcade is reversed. Maxillary canine and first premolar transposition (Mx.C.P1 transposition) is most commonly observed. Data from Native Americans samples are lacking. The purpose of this study was: 1) to document the occurrence of Mx.C.P1 transposition, and 2) to generate information on the prevalence of this transposition type among world populations. Eleven cases (M = 5, F = 4, ? = 2) of Mx.C.P1 transposition were identified in skeletal samples from Pecos Pueblo (n = 500) and Sambrito Village (n = 10), both in northern New Mexico. Nine cases were unilateral, 6 affecting the right side and 3 affecting the left side. The remaining 2 cases were bilateral. The prevalence rate of Mx.C.P1 transposition in African and Native American samples, including Pecos Pueblo (1.8%), is higher than in samples from Scotland, Sweden, Saudi Arabia, and India. Mx.C.P1 transposition frequencies vary between geographically distinct populations, although sample composition may be a factor contributing to sample variation. Am J Phys Anthropol 116:45–50, 2001. © 2001 Wiley‐Liss, Inc.
Craniometric variation and the settlement of the Americas: Testing hypotheses by means of R‐matrix and matrix correlation analyses
Authors: González‐José Rolando , Dahinten Silvia L. , Luis María A. , Hernández Miquel , Pucciarelli Hector M.
Published: August 2002

New archaeological findings and the incorporation of new South American skull samples have raised fundamental questions for the classical theories of the Americas' settlement. The aim of this study was to estimate craniometric variability among several Asian and Native American populations in order to test goodness of fit of the data to different models of ancient population entries and dispersions into the New World. Our data set includes Howells' variables recorded on East Asian, North American, and South American natives (except for Na‐Dene speakers). Five Fuego‐Patagonian samples and one Paleoamerican sample were also included. A multivariate extension of the R‐matrix method for quantitative traits was used to obtain Fst values, which were considered estimations of intergroup variation. Three main models for the peopling of the New World were represented in hypothetical design matrices. Matrix permutation tests were performed to quantify the fit of the observed data with 1) geographical separation of the samples and 2) three ways of settlement, which were the Three Migration Model (TMM), the Single Wave Migration model (SWM), and the Two Components Settlement Model (TCS). R‐matrix results showed high levels of heterogeneity among Native Americans. Matrix permutation analyses suggested that the model involving high Amerindian heterogeneity and two different morphological patterns or components (derived “Mongoloid” vs. generalized “non‐Mongoloid”) explains better the variation observed, even when the effects of geographical separation are removed. Whether these patterns arose as a result of two separate migration events or by local evolution from Paleoamericans to Amerindians remains unresolved. Am J Phys Anthropol 116:154–165, 2001. © 2001 Wiley‐Liss, Inc.
Case‐control study of the extended tau gene haplotype in Parkinson's disease
Authors: Maraganore Demetrius M. , Hernandez Dena G. , Singleton Andrew B. , Farrer Matthew J. , McDonnell Shannon K. , Hutton Michael L. , Hardy John A. , Rocca Walter A.
Published: August 2002

We investigated the association of Parkinson's disease with tau gene haplotypes. In a sample of 319 unrelated Parkinson's disease patients and 196 control subjects, we observed an increased risk of Parkinson's disease for persons with the H1/H1 genotype (odds ratio = 1.5; 95% confidence interval: 0.98–2.23); however, the finding was not statistically significant. The results remained similar after adjusting for the possible misclassification of progressive supranuclear palsy patients as Parkinson's disease, but became statistically significant after restricting the analysis to nondemented subjects.
Diastereoselective addition of trimethylsilyl cyanide to chiral O‐, S‐ and N‐heterocyclic aldimines
Authors: Iovel Irina , Golomba Lena , Popelis Juris , Lukevics Edmunds
Published: August 2002

Systematic investigation of asymmetric trimethylsilylcyanation of heterocyclic azomethines has been realized. The addition of trimethylsilyl cyanide to optically active furan, thiophene and pyridine aldimines, derived from (R)‐ and (S)‐1‐phenylethylamine, was studied in the presence of Lewis acids, and a series of the corresponding α‐amino nitriles was obtained in fair to good yields (up to 91%). Unsaturated nitriles were also formed from pyridine imines. The sense of asymmetric induction and the degree of diastereoselectivity in the synthesis of α‐amino nitriles were determined by means of 1H NMR. The stereochemical outcome is a result of the same sense of asymmetric induction: Re face attack to the (S)‐imines and Si face addition to the (R)‐imines took place. The (R,R)‐ (up to 81%) or (S,S)‐ (up to 87%) α‐amino nitriles predominated in the products obtained from the all furan, thiophene and pyridine (R)‐ or (S)‐imines respectively. Copyright © 2002 John Wiley & Sons, Ltd.
Postcrosslinking of macroporous styrene–divinylbenzene copolymers via pendant vinyl groups: Effect of the starting copolymers on the pore structure of the postcrosslinked products
Authors: Zhou Chuncai , Yan Jun , Cao Zhinong
Published: August 2002

In the presence of anhydrous ferric chloride as a Friedel–Crafts catalyst, the postcrosslinking reaction of macroporous styrene–divinylbenzene (St–DVB) copolymers synthesized under different conditions was carried out with 1,2‐dichloroethane as a solvent. Without an externally added crosslinking agent, the specific surface area and pore volume, for copolymers with different DVB isomers or different DVB contents after reaction, in most cases increased significantly, and the increase was found to be heavily dependent upon the amount of the pendant vinyl groups in the starting copolymers. These results further confirm the role of the pendant vinyl groups in creating new crosslinking bonds in addition to those created by a free‐radical crosslinking reaction in the starting copolymers, and an alkylation reaction of the vinyl groups with neighboring aromatic rings is believed to dominate the course of the postcrosslinking at a relatively high level of the vinyl group contents. The synthesis conditions, including the n‐heptane content in a mixed diluent and the amount of the diluent, under which the starting copolymers were synthesized, play an important role in the increase of the surface area and pore volume of the copolymers after postcrosslinking. The effect of these conditions is attributed mainly to the swelling ability of the starting copolymers thus obtained in the solvent used for reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1668–1677, 2002
Unsaturated polyester as compatibilizer for styrene–butadiene (SBR)/acrylonitrile–butadiene (NBR) rubber blends
Authors: Mansour S. H. , Tawfik S. Y. , Youssef M. H.
Published: August 2002

The effect of the addition of 5 and 10 phr of unsaturated polyester resin (UPE) on the compatibility and physicomechanical properties of styrene–butadiene (SBR) and acrylonitrile–butadiene (NBR) rubber blends was studied. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), electrical, and ultrasonic techniques were used to determine the degree of the compatibility (DC). The results obtained revealed that, by the addition of 10 parts per hundred parts of rubber (phr) UPE as a compatibilizer for SBR/NBR blends, the degree of compatibility was greatly enhanced. The rheological and mechanical properties of the blends were also improved. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2314–2321, 2002
Functionally gradient silicone sheet made by treatment of swelling and polymerization with n‐butyl methacrylate
Authors: Horiuchi Kenichi , Suzuki Makoto , Tanaka Kotaro
Published: August 2002

A silicone sheet was dipped into n‐butyl methacrylate monomer including benzoyl peroxide and was swollen for 0.5 h at 23°C. Then, the sheet was put into a glass tube equipped with a three‐way stopcock and was deoxygenated by freezing under dry nitrogen. Polymerization was carried out by heating at 80°C for 2 h under dry nitrogen. The resultant sheet was a component gradient silicone sheet with poly‐n‐butylmethacrylate. The content of poly‐n‐butylmethacrylate increased gradually from either surface to the middle of the sheet. This phenomenon was assumed to occur because of the volatilization of n‐butyl methacrylate monomer during the polymerization. The properties of the sheet include increased tear strength and decreased gas permeability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3152–3155, 2002; DOI 10.1002/app.10177
Surface immobilization of star‐shaped poly(ethylene oxide) on poly(dimethylsiloxane)
Authors: Park Yong Soon , Kang Yong Soo , Won Jongok
Published: August 2002

A thin layer of star‐shaped poly(ethylene oxide) (PEO) (starPEO), on the polydimethylsiloxane (PDMS) membrane was prepared by a simple immobilization procedure. Photoreactive molecules were introduced on the surface of the polymeric support to achieve the formation of thin starPEO film from the materials having no functional groups. This novel technique enabled us to immobilize any kind of chemical, especially one that had no functional groups, and readily to control the amount of immobilization. The gas permeation properties of the starPEO‐immobilized PDMS membranes were investigated for pure propane and propylene. The permeance of gases were found to decrease in the starPEO‐immobilized PDMS membranes, although the ideal separation factors for propylene/propane were increased with the loading amount of silver ions, because of the facilitation action of silver ions in the immobilized PEO unit on the PDMS membranes, as propylene carriers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2369–2373, 2002
Disperse dyeing of polyester fibers: Kinetic and equilibrium study
Authors: Georgiadou K. L. , Tsatsaroni E. G. , Eleftheriadis I. C. , Kehayoglou A. H.
Published: August 2002

The effect of temperature on the dyeing rate constant k, diffusion coefficient D, time of half‐dyeing t1/2 was evaluated for the dyeing of polyester fibers with two disperse dyes, an azo and an anthraquinone dye. Activation energies of diffusion E were calculated. The polyester dyeing equilibrium was also studied and the partition coefficient K and standard affinity Δμ° at various temperatures were determined for the anthraquinone dye. Standard enthalpy ΔH° and standard entropy ΔS° of dyeing were also obtained. The same equilibrium parameters were not obtained for the azo dye because of its dyeing behavior. A similar kinetic and equilibrium study was made for the pure azo and anthraquinone compounds free from the dispersing agents present in the commercial dyes and the results are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2785–2790, 2002; DOI 10.1002/app.10254
Synthesis in inverse emulsion and properties of water‐soluble associating polymers
Authors: Pabon Martial , Corpart Jean‐Marc , Selb Joseph , Candau Françoise
Published: August 2002

An inverse, free‐radical emulsion polymerization technique was designed for the preparation of copolymers of acrylamide and sodium acrylate modified with low amounts (<0.5 mol %) of a series of amphiphilic comonomers, the isooctylphenoxy–poly(oxyethylene)(n) methacrylates (1 ≤ n ≤ 12). The products of the reaction were hydrophobically modified water‐soluble polymers (HMWSPs) of high molecular weight encapsulated within water droplets dispersed in an organic medium. Kinetic studies showed that the full‐conversion samples were rather homogeneous in composition because of the specificity of the process. A mechanistic scheme is proposed that accounts for the incorporation level of the amphiphilic comonomer as a function of its hydrophile–lipophile balance and the nature of the redox initiator (hydrophilic or lipophilic). The rheological properties of the HMWSPs in aqueous solutions were investigated as a function of the comonomer content and the nature of the initiator with steady‐flow experiments. The thickening properties were directly correlated to the conditions of synthesis and were optimal when the initiator and the amphiphilic comonomer were located in two distinct phases. A maximum in viscosity was observed for a hydrophobe content of about 0.3 mol %. An examination of the viscosity as a function of the shear rate and time showed that these solutions had all the characteristics of associating polymers. The complex rheological behavior was the result of the balance between interchain and intrachain hydrophobic liaisons and the kinetics of disorganization and reorganization of the network structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1418–1430, 2002; DOI 10.1002/app.10337
Rheological properties of polypropylenes with different molecular weight distribution characteristics
Authors: Fujiyama Mitsuyoshi , Kitajima Yoshiyuki , Inata Hitoshi
Published: August 2002

Relationships between the rheological properties and the molecular weight distribution of two polypropylene series with different molecular weight distribution characteristics were studied. The end correction coefficient in capillary flow is determined by the molecular weight Mw and the molecular weight distribution Mw/Mn, and is higher as both characteristic values are larger. The die swell ratio at a constant shear rate depends on Mw, Mw/Mn, and Mz/Mw, and is higher as the three characteristic values are larger. The critical shear rate at which a melt fracture begins to occurs depends on the molecular weight Mw and the molecular weight distribution Mz/Mw, and is proportional to Mz/Mw2 in a log–log plot. The critical shear stress does not depend on the molecular weight, and is higher as Mz/Mw is higher. The zero‐shear viscosity is determined by a molecular weight of slightly higher order than Mw, and the characteristic relaxation time is determined by Mz. The storage modulus at a constant loss modulus scarcely depends on the molecular weight, and is higher as the molecular weight distribution Mw/Mn is higher. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2128–2141, 2002
High Tg second‐ order nonlinear optical poly(urethane–imide)s prepared from disperse Red 19, pyromellitic dianhydride, and tolylene diisocyanate
Authors: Sui Yu , Lu Jiong‐Xin , Yin Jie , Wang Dong , Zhu Zi‐Kang , Wang Zong‐Guang
Published: August 2002

A series of poly(urethane–imide)s with high glass transition temperatures were easily prepared from a commercial nonlinear optical (NLO) chromophore (Disperse Red 19), pyromellitic dianhydride (PMDA), and 2,4‐tolylene diisocyanate (TDI). The resulting polymers possessed good solubility and high glass transition temperatures (231–272°C) and thermal decomposition temperatures. They exhibited excellent film‐forming properties and good‐quality films were easily obtained by spin coating. These polymers also possessed a high coefficient of optical nonlinearity with good temporal stability of the dipole orientation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 944–949, 2002
Graft copolymerization of acrylonitrile and methyl methacrylate monomer mixtures on crumb natural rubber
Authors: Okieimen F. E. , Urhoghide I. N.
Published: August 2002

Graft copolymerization of mixtures of acrylonitrile and methyl methacylate on crumb natural rubber was carried out in toluene at 60°C. The nitrogen content of the grafted copolymer was determined by elemental analysis and used to estimate the composition of the copolymer samples. It was found that the amount of acrylonitrile monomeric units incorporated into the polymer was disproportionately lower than the acylonitrile content of the feed and explanations in terms of the e‐value of the monomers and the inherent heterogenous nature of the polymerization mixture were offered. The miscibility of the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) with poly(vinyl chloride) was studied by viscometry, differential scanning calorimetry, and phase contrast microscopy. It was found that the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) formed semimiscible blends with poly(vinyl chloride). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1872–1877, 2002; DOI 10.1002/app.10474
The study of rapid curing crease‐resistant processing on cotton fabrics. II. Effect of poly(ethylene glycol) on physical properties of processed fabrics
Authors: Shih Chung‐Yang , Huang Kuo‐Shien
Published: August 2002

This study aimed to examine the effects of the addition of poly(ethylene glycol) (PEG) on the physical properties of processed cotton fabrics in a rapid heat‐curing crease‐resistant process. Our results show that this addition influences the moisture absorbency, crease resistance in both dry and wet conditions, and tensile strength preservation rate of the processed fabrics. Moreover, with such addition, the use of higher temperature in the process would enhance the moisture absorbency and dry–wet crease resistance but reduce the tensile strength preservation rate. The optimum condition for processing cotton fabric is to use PEG with a molecular weight of 1000 at a concentration of 10%, heated at 200°C for 30 s. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1008–1012, 2002
Effect of PVP in dispersion and seeded dispersion polymerizations
Authors: Wang Danni , Dimonie Victoria L. , Sudol E. David , El‐Aasser Mohamed S.
Published: August 2002

The outcome of seeded dispersion polymerizations of n‐butyl acrylate (BA) and styrene (St) in terms of the success of growing the seed particles without nucleating new particles or generating coagulum was found to be dependent on the seed type (poly[n‐butyl acrylate] [ PBA] or polystyrene [PSt]), the second‐stage monomer (BA or St), and the type of polyvinylpyrrolidone (PVP) stabilizer (PVP K30 or PVP K90). All seeds were first cleaned of excess stabilizer by medium replacement before the seeded polymerizations. In general, successful particle growth was achieved when the second‐stage polymerization employed PVP K30 (1 wt%) as the stabilizer. In contrast, nearly all reactions employing PVP K90 (1 wt%) as the second‐stage stabilizer resulted in the nucleation of a second crop of particles. These phenomena were further investigated by carrying out dispersion polymerizations using the supernatant obtained by separating the seeds from the second‐stage media (containing monomer). The results paralleled those in the seeding studies and were explained by the presence of small amounts of grafted PVP created in situ during the preparation of the seeds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2721–2732, 2002
Effect of surface modification of glass wool on the mechanical and electrical properties of polypropylene/modified glass‐wool composites
Authors: Turky G. M. , Abd El‐Reheim M. H. , Badran A. S.
Published: August 2002

The surface of glass wool (GW) was modified by two different methods, either by grafting methyl acrylate (MA) onto GW in the presence of potassium persulfate (PPS) as initiator, or by adsorbing stearic acid (AS) as surface active agent onto the GW surface. It was found that conversion and grafting yield of poly(methyl acrylate) (PMA) onto the GW surface increased with increasing initiator concentration, whereas by modifying the GW surface by adsorption of SA, the adsorption of SA was found to be high at small values of equilibrium concentrations and two distinct plateau regions were observed. Mechanical and electrical properties of polypropylene (PP) sheets loaded with modified GW were measured. The obtained data showed that the presence of PMA as grafted polymer onto the GW surface has a plasticizing effect on the prepared PP composites. On the other hand, SA, as a surface modifier for GW, acts as a reinforcing agent for the formed PP composites, which have very good dielectric properties. From the obtained results, one can deduce that the prepared PP/GW composites have promising dielectric properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1061–1069, 2002
Polymerization kinetics of styrene using coordination catalysts containing rare earth compounds
Authors: Kothandaraman H. , Sangeetha D. , A. A. Sriramulu  , Nayagam M. P. M. , Aminabhavi T. M.
Published: August 2002

Polymerization reactions of styrene in toluene at 60°C have been carried out using Ziegler–Natta catalysts containing praseodymium trichloroacetate‐triethyl aluminum [Pr(OCOCCl3)3‐Et3Al] (system I) and praseodymium trichloroacetate‐diethyl aluminum bromide [Pr(OCOCCl3)3‐Et2AlBr] (system II). The reaction was of first order with respect to both monomer and catalyst concentrations. At a stoichiometric ratio of Al/Pr = 8, an optimum catalytic activity was observed. The activation energies for systems I and II ranged between 21.06 kJ/mol and 13.79 kJ/mol, respectively. System I was white in color and system II is waxy. Molar masses of systems I and II were 9.1 × 105 and 2.2 × 104, respectively. The polymers were characterized by viscometry and 1H NMR methods. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 995–1002, 2001
The effects of atacticity, comonomer content, and configurational defects on the equilibrium melting temperature of monoclinic isotactic polypropylene
Authors: Bond Eric Bryan , Spruiell Joseph E.
Published: August 2002

A series of isotactic polypropylenes were investigated to account for total defect content using xylene fractionation and carbon‐13 NMR experimental methods. The defects of interest were percent atactic content, copolymer content, and configurational defects. Experimental equilibrium melting temperatures were obtained for each material using the Gibbs‐Thomson equation and extrapolation to infinite crystal thickness or the Hoffman‐Weeks analysis. The experimental equilibrium melting temperature was then compared with the theoretical equilibrium melting temperature predicted by Flory's melting point depression model. Flory's model was found to fit the experimental data using an equilibrium melting temperature of 186°C when configurational defects are ignored. However, to account for all defects, the equilibrium melting temperature for 100% isotactic polypropylene must be increased from 186 to 192°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 229–236, 2001
Action of hydrocarbon and ester plasticizer in urethane elastomer for sealing purposes
Authors: Jeczalik Jerzy
Published: August 2002

A comparison of the effects of two types of modifiers, anthracene oil (hydrocarbon) and dioctyl phthalate (ester), on physical and mechanical properties of urethane elastomers prepared from polyetherols (propylene oxide derivatives of various functionalities and MW) and TDI was performed. The aim of the study was to assess their suitability as binders in permanently elastic urethane sealants for use in construction. The urethane elastomers under investigation were synthesized by a prepolymer method. The modifiers, added to the reactive mixture before curing, were found to be fully compatible with the urethane elastomers and did not interfere with the curing process. The usable range of application for both modifiers was found to be up to 40 phr. Over this range the modified urethane elastomers are viscoelastic liquids. The hydrocarbon modifier does enhance the hydrophobic properties of urethane elastomer, at a lower degree of crosslinking. It was found that modified urethane elastomers may be good binders for sealants, although their long‐term sealing properties must be confirmed under field conditions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 523–529, 2001
Characterization of structural heterogeneity of polyurethane coatings
Authors: Paolpi M. , Lacabanne C.
Published: August 2002

The thermal analysis techniques—Differential Scanning Calorimetry and ThermoStimulated Current—have been used to characterize a polyurethane high solid coating. The glass transition temperature, as determined by DSC, is 60°C. Below this glass transition temperature, an αsub dielectric relaxation mode has been observed; it corresponds to cooperative movements precursor of the glass transition. The αss dielectric relaxation mode, located at ≈ Tg has been attributed to movements of soft sequences of the amorphous phase liberated at the glass transition temperature. The analysis of the fine structure shows that they are constituted of elementary processes characterized by relaxation times following a compensation law. Above Tg, the αhs dielectric relaxation of hard sequences has been shown. It corresponds to hard sequences hydrogen bonded in polyurethane. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2786–2790, 2001
Ultrasonic disassociation of EVA random copolymer in dilute solutions
Authors: Qian J. W. , Zhou G. H. , An Y. L.
Published: August 2002

Ultrasonic disassociation of the ethylene–vinyl acetate (EVA) random copolymer in 1,2‐dichloroethane (DCE), cyclohexane (CYH), and their solvent mixtures was investigated using viscometry and dynamic laser light scattering (DLLS). It was found that the disassociation of the EVA aggregates in solutions increases with increasing the time and intensity of ultrasonic shearing and approaches invariant finally. This phenomenon is especially marked for the EVA copolymer with low vinyl acetate (VA) content in the polar solvent of DCE at higher concentration and lower temperature. This is attributed to disassociation of the ethylene segment of the EVA random copolymer in dilute solutions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2798–2802, 2001
Studies on the dipping characteristics of RVNRL and NR latex compounds
Authors: Sasidharan K. K. , Joseph Rani , Rajammal G. , Pillai P. Viswanatha , Gopalakrishnan K. S.
Published: August 2002

The dipping characteristics of radiation‐vulcanized natural rubber latex and natural rubber latex compounds were investigated with a lab‐model semiautomatic dipping machine. The effect of the variation of the speed of immersion and withdrawal, dwell time, compound viscosity, and concentration of coagulant on the thickness of the latex deposit was investigated. The results of the study show that the deposit thickness depends on the withdrawal speed of the former, the concentration of the coagulant, dwell times, and the viscosity of the latex compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3141–3148, 2001
Study of ethylene polymerization catalyzed by nBu‐Cp2ZrCl2/MAO catalytic system and their polymerization kinetics
Authors: Wang L. , Zhang P. Y. , Jiang S. , Feng L. X.
Published: August 2002

Polyethylene was prepared by using a nBu‐Cp2ZrCl2/MAO catalytic system. Considering the reactivation of Zr species, a novel and reasonable mathematical model of kinetics has been developed and the kinetic profiles of ethylene polymerization have been fitted satisfactorily. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3186–3189, 2001
Thermal behavior of elastomer–resin mixtures used as friction materials
Authors: Camino G. , Alba E. , Buonfico P. , Vikoulov K.
Published: August 2002

This study looks at the thermal behavior of mixtures of nitrile‐butadiene rubber (NBR) with a resol or a novolac resin. When heated in the 200–300°C range, NBR became hard and insoluble because of exothermic curing and cyclizing chain reactions involving the double bonds of its butadiene units and the nitrile groups of its acrylonitrile units. The NBR proved to be compatible with the novolac but not the resol. Heating increased the modulus of elasticity of the mixtures, which was due to crosslinking of the resin and the rubber. Preliminary linking of the resin resulted in phase separation in the novolac and prevented curing of the rubber when the mixture was heated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1346–1351, 2001
Unsteady stirring method staged used in suspension polymerization of styrene
Authors: Yang Bin , Takahashi Koji , Takeishi Makoto
Published: August 2002

The results of an unsteady stirring method staged, used in the suspension polymerization of styrene in a lab‐scale batch reactor, are presented. Variation of droplet size during the whole polymerization process under the unsteady stirring condition, compared with that under a steady stirring condition, was found to be small. According to the variable droplet size character, two methods were used to divide the polymerization process into four stages and the unsteady stirring method was used in only one stage of each experimental run. By these operations, the optimum operation of obtaining large particle product with uniform particle size distribution was achieved. The results suggest that controlling the droplet coalescence process is more important than controlling the initial droplet size distribution to obtain uniform final particle products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1873–1881, 2001
Enhanced dynamic mechanical and shape‐memory properties of a poly(ethylene terephthalate)–poly(ethylene glycol) copolymer crosslinked by maleic anhydride
Authors: Chun Byoung Chul , Cha Sang Hyuk , Chung Yong‐Chan , Cho Jae Whan
Published: August 2002

Dimethyl terephthalate (DMT) and ethylene glycol (EG) were used for the preparation of poly(ethylene terephthalate) (PET), and poly(ethylene glycol) (PEG) was added as a soft segment to prepare a PET–PEG copolymer with a shape‐memory function. MWs of the PEG used were 200, 400, 600, and 1000 g/mol, and various molar ratios of EG and PEG were tried. Their tensile and shape‐memory properties were compared at various points. The glass‐transition and melting temperatures of PET–PEG copolymers decreased with increasing PEG molecular weight and content. A tensile test showed that the most ideal mechanical properties were obtained when the molar ratio of EG and PEG was set to 80:20 with 200 g/mol of PEG. The shape memory of the copolymer with maleic anhydride (MAH) as a crosslinking agent was also tested in terms of shape retention and shape recovery rate. The amount of MAH added was between 0.5 and 2.5 mol % with respect to DMT, and tensile properties and shape retention and recovery rate generally improved with increasing MAH. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 27–37, 2002
Effect of chlorine substitution in 4,4′‐diaminodiphenylmethane hardener on shelf life and mechanical properties of epoxies
Authors: Jagadeesh K. S. , Gururajarao J. , Shashikiran K. , Ambekar Sarvottam Y.
Published: August 2002

Curing of N,N,N′,N′‐tetraglycidyldiaminodiphenylmethane with new curing agents like 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane and 2,2′‐dichloro‐4,4′‐diaminodiphenylmethane in comparison with diaminodiphenylmethane and 4,4′‐diaminodiphenylsulphone (DDS) was carried out using dynamic differential scanning calorimetry. The shelf life of various epoxy formulations was evaluated by the residual cure exotherm method. The glass‐transition temperatures of cured epoxy formulations were determined using dynamic mechanical analysis. The mechanical properties such as the tensile strength, tensile modulus, flexural strength, and Izod impact strength were also evaluated and compared. The activation energy, frequency factor, and shelf life of chloro‐substituted hardener formulations were high as compared to those of unsubstituted hardener formulations. The marginal differences in the glass‐transition temperature, tensile strength, tensile modulus, and flexural strength and the small decrement in the Izod impact strength values were interpreted in terms of chlorine substitution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3082–3088, 2002; DOI 10.1002/app.2337
Developments in the application of photography to ecological monitoring, with reference to algal beds
Authors: Ducrotoy Jean‐Paul A. , Simpson Stephen D.
Published: August 2002

1. The potential for using photographic methods in ecological monitoring of intertidal rocky shores was investigated at two scales: the scale of a bay, and at sampling quadrat level.

2. The macroalgal beds at Selwicks Bay, Flamborough Head (north Humberside Coast, England) were used as a case study.

3. At each station on three 90 m transects, a photograph was taken of a 50 cm2 quadrat. These images were analysed using SigmaScan™ to measure the cover of algal species. These data were highly correlated with field data collected using a grid quadrat.

4. Ground techniques were developed for drawing a scaled overhead map of the bay. The potential for a quantitative survey of the extent of the algal beds using cliff top photographs was investigated. The photographs were merged, and rectified using Arc/Info™ (a Geographical Information System package) to produce scaled overhead images of the bay.

5. The two complementary methods developed are suitable for involving amateur naturalists into field‐data collection. They were also designed to meet long‐term statutory monitoring requirements. They are quick, so are well suited to intertidal areas where field sampling windows are limited. In long‐term monitoring strategies, the use of photography produces interactive permanent records of the sample area for back reference. Reporting on the conservation status of sites of European interest could be greatly facilitated by such techniques.

6. There are obvious applications for overseas monitoring and base‐line surveys, which demand large data sets to be collected in limited periods of time. Copyright © 2001 John Wiley & Sons, Ltd.
A method for estimating the extent of standing fresh waters of different trophic states in Great Britain
Authors: Palmer M.A. , Roy D.B.
Published: August 2002

1. The total area of standing fresh water in Great Britain has been estimated at approximately 2400 km2. The aim of the work described in this paper was to estimate the extent of the dystrophic, oligotrophic, mesotrophic and eutrophic habitat types making up this total.

2. Botanical survey data collected by the statutory nature conservation agencies provided habitat type and surface area for 3500 water bodies, mostly in Scotland. Because survey in England and Wales had been less thorough than in Scotland, it was not possible to estimate the areas of habitat types simply by direct extrapolation from the survey sample to the total resource of standing water in Great Britain.

3. A system of Trophic Ranking Scores (TRS) has been developed for aquatic plant species. Using plant records from the Biological Records Centre, a mean TRS for each 10×10 km square was produced, and Great Britain was divided into TRS bands. For each of these bands, the percentage by surveyed area of each freshwater habitat type was calculated. These percentages were applied to the total area of standing water in each TRS band, obtained from Ordnance Survey summary statistics, in order to predict the proportions of the different habitat types likely to occur in each band. The extent of these habitats in Great Britain as a whole could then be calculated.

4. Estimates produced by this method of the extent of the four standing freshwater habitat types in Great Britain are: dystrophic — 11 km2 (0.5%); oligotrophic — 1445 km2 (60%); mesotrophic — 267 km2 (11%); eutrophic — 679 km2 (28%).

5. The application of this work to nature conservation is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Histochemical and biochemical analysis of phospholipase C isoforms in normal human gastric mucosa cells
Authors: Di Baldassarre Angela , Marchisio Marco , Felaco Mario , Antonucci Adriano , Centurione Lucia , Grilli Alfredo , Di Valerio Valentina , Cutroneo Giuseppina , Schiavone Cosima , Miscia Sebastiano , Ianetti Giovanni
Published: August 2002

The expression and activity of PIP2‐specific phospholipase C (PLC) in healthy human gastric mucosa cells were investigated by means of Western blotting, immunohistochemistry and in vitro activity assays. The results provide direct evidence for an almost exclusive expression of the PLC beta family and at the same time supply a cellular cartography of each represented isoform of this family. In this context, the putative roles of each isoform in the signaling events regulating the gastric mucosa metabolic machinery are discussed. These data provide a unique map of the specific expression and cellular distribution of the most represented PLC isoforms in healthy human gastric mucosa cells, which may constitute a reference point in future studies aimed at highlighting possible cytochemical and biochemical hallmarks of metaplastic or malignant transformation. Anat Rec 262:440–444, 2001. © 2001 Wiley‐Liss, Inc.
Use of hair pores to determine the orientation of collagen fibers in skin
Authors: Osaki Shigeyoshi
Published: August 2002

Most people are interested in recovery of skin defects caused by burn, scald or trauma from the aesthetic and functional point of view. It will occupy an important role for successful skin graft for patients with such skin defects that the orientation of collagen fibers in the grafted skin matches to the fiber orientation in surrounding skin. There have been, to my best knowledge, no methods for determining the orientation of collagen fibers in the skin from the clinical point of view. Recently, the author has found a new method for directly determining the collagen‐fiber orientation without cutting samples from a calf leather by analyzing the anisotropic shape of hair pore. Its principle is based on the quantitative evaluation of collagen‐fiber orientation by approximating a hair pore to an ellipse. The results obtained by the new method using hair pores were supported by the microwave method, mechanical measurements and scanning electron microscopy. Such a method will be applicable for determining the orientational distribution of collagen fibers in skins of animals and humans and give a valuable probe for performing skin grafting based on the scientific data of hair pores. Anat Rec 263:161–166, 2001. © 2001 Wiley‐Liss, Inc.
Influence of calcium on Manduca sexta plasmatocyte spreading and network formation
Authors: Willott Elizabeth , Hallberg Constance A. , Tran Hung Q.
Published: August 2002

Plasmatocytes are a class of insect hemocytes important in the cellular defense response. In some species, they are phagocytic, protecting the insect from smaller pathogens. In many insects, they work in concert with other hemocytes (particularly other plasmatocytes and granular cells) to form nodules and to encapsulate foreign material. To perform these functions, plasmatocytes attach to, spread on, and surround suitable targets. Because of their importance, because we had previously observed that prolonged incubation of hemocytes in solutions containing the divalent cation chelator ethylenediaminetetraacetic acid (EDTA) inhibited plasmatocyte spreading, and because of the importance of divalent cations in many immune‐related functions, we investigated the effect of calcium and magnesium on spreading of plasmatocytes from fifth instar Manduca sexta larvae. On glass slides, plasmatocytes spread more quickly and elongated in Grace’s medium containing 5 mM calcium, compared to calcium‐free medium. In the presence of calcium, plasmatocyte adhesion, spreading, and network formation were not visibly different in magnesium‐free and magnesium‐containing Grace’s medium. Using immunomicroscopy with a monoclonal antibody specific for plasmatocytes, we measured the length and width of plasmatocytes incubated with several different concentrations of calcium. Plasmatocyte length positively correlated with calcium concentration to 5 mM (maximum concentration tested and approximately the hemolymph concentration). Mean plasmatocyte width was less in 0 and 5 mM calcium than in 0.05 or 0.5 mM calcium. On plastic, hemocytes survived longer than on glass (they survived beyond 24 h) and, in 5 mM calcium, formed an extensive network readily visible by phase‐contrast microscopy. This network was never as extensive in the absence of calcium. Network formation in the absence of magnesium, but presence of calcium, resembled network formation in standard Grace’s medium. Arch. Insect Biochem. Physiol. 49:187–202, 2002. © 2002 Wiley‐Liss, Inc.
Cholinergic regulation of the corpora allata in adult male loreyi leafworm Mythimna loreyi
Authors: Kou Rong
Published: August 2002

The direct effect of acetylcholine on the activation of the corpora allata (CA) was investigated in the adult male loreyi leafworm, Mythimna loreyi. Acetylcholine, in the presence of the choline esterase inhibitor physostigmine (50 μM), elicited a stimulatory effect on juvenile hormone acids (JHAs) release from the CA. Maximum effect was obtained at concentrations of 10 and 50 μM. Repeated administration of 10 μM acetylcholine on the same CA did not elicit similar stimulatory effect. Since JHA release can be significantly activated by carbachol and not by nicotine, this cholinergic effect is likely to belong to the muscarinic type. The effect of acetylcholine was significantly antagonized by gallamine triethiodide (M2 antagonist) and 4‐DAMP (M3 antagonist), pirenzepine (M1 antagonist), and tropicamide (M4 antagonist) were ineffective. It is concluded that in the adult male M. loreyi, the cholinergic regulation of CA is most likely via M2 and M3 muscarinic receptors.Arch. Insect Biochem. Physiol. 49:215–224, 2002. © 2002 Wiley‐Liss, Inc.
Seasonal changes in glycerol content and enzyme activities in overwintering larvae of the Shonai ecotype of the rice stem borer, Chilo suppressalis Walker
Authors: Li Yi‐Ping , Ding Lei , Goto Michiyo
Published: August 2002

Enzymes associated with glycogen metabolism and glycerol synthesis in larvae of the Shonai ecotype of the rice stem borer, Chilo suppressalis, were investigated over the winter in 2000–2001. Glycerol content was scarcely detected in September and October, rapidly increased in November and December, peaked in January, and then decreased. Glycogen was converted to glycerol over the winter until February, and glycerol was reconverted to glycogen in March. The trehalose content remained constant over the winter. The activities of enzymes associated with glycerol synthesis changed with the season. Glycerol accumulation was accomplished by activation of glycogen phosphorylase, inhibition of fructose‐1,6‐bisphosphatase and pyruvate kinase, and activation of enzymes associated with glycerol synthesis, mainly glyceraldehyde‐3‐ phosphatase and polyol dehydrogenase with glyceraldehyde activity. These changes led to a diversion of triose phosphates into the pathway of glycerol synthesis. However, activities of the two initial enzymes of the hexose monophosphate shunt were not activated and remained relatively constant, but high during the period of active glycerol synthesis. Both decreasing temperature in the field and the transition from the diapause to the post‐diapause state may be responsible for the changes in activities of enzymes associated with glycerol synthesis. Arch. Insect Biochem. Physiol. 50:53–61, 2002. © 2002 Wiley‐Liss, Inc.