bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal cross‐linking and pyrolytic conversion of poly(ureamethylvinyl)silazanes to silicon‐based ceramics
Authors: Li Ya‐Li , Kroke Edwin , Riedel Ralf , Fasel Claudia , Gervais Christel , Babonneau Florence
Published: August 2002

The aim of this work was to study the pyrolytic conversion of a novel commercial polysilazane, poly(ureamethylvinyl)silazane (PUMVS; Ceraset™, Allied Signal Composites Inc., USA), into silicon‐based ceramics. The precursor was thermally cross‐linked and pyrolyzed between 200 and 1700 °C under argon or nitrogen atmosphere and the products were investigated by spectroscopic techniques (FTIR and Raman spectroscopy, solid‐state NMR), elemental analysis and simultaneous thermal analysis coupled with mass spectrometry. Upon heating under argon, the starting liquid precursor transformed into an infusible solid polymer at T > 250 °C with a conversion yield of >95 wt%. The cross‐linking solidification occurred predominantly through hydrosilylation or addition reaction involving vinyl groups. Subsequent pyrolysis of the cross‐linked products around 1000 °C in argon yielded amorphous silicon carbonitride ceramics with a composition of SiN0.82C0.86. The overall ceramic yield (with respect to the starting PUMVS) was around 70 wt%, which was found to be independent of the initial cross‐linking step. Solid‐state NMR (29Si and 13C) revealed that the amorphous silicon carbonitrides contain predominately CSiN3 units. There is evidence for the formation of free amorphous carbon between 700 and 800 °C. Graphitic phases were detected by X‐ray diffraction in the samples heated to T > 1000 °C at high heating rates. Upon annealing at T > 1500 °C, the excess carbon reacted completely with the silicon (carbo)nitride to form SiC and nitrogen. The final ceramics contained a large amount of crystalline SiC (∼90 wt%), and were free of excess carbon or silicon. Therefore, PUMVS is an ideal precursor for the formation of high‐quality SiC‐based ceramics. Copyright © 2001 John Wiley & Sons, Ltd.
Spermiotoxicity and embryotoxicity of triphenyltin in the sea urchin Paracentrotus lividus Lmk
Authors: Moschino Vanessa , Marin Maria Gabriella
Published: August 2002

The most important sources of pollution by triphenyltin (TPT) in marine coastal ecosystems are its employment as a fungicide in agriculture and, in association with tributyltin, as a biocide in antifouling paints. In this study, spermiotoxicity and embryotoxicity (from post‐fertilization to pluteus stage) experiments were carried out to clarify better the ecotoxicological effects of TPT during the development of the sea urchin Paracentrotus lividus. Sperm exposed to triphenyltin acetate (TPTA) for 60 min showed a significantly reduced capability to fertilize eggs even at the lowest TPTA concentration of 0.1 µg l−1. In proportion to increasing TPTA concentrations, the percentage of fertilized eggs decreased, falling to 45% at 10 µg l−1, the maximum TPTA concentration tested. In embryotoxicity experiments at 48 h post‐fertilization, the length of the pluteus somatic rods was significantly reduced (P < 0.001) at 1.5 µg l−1 and above. Progressive increases in skeletal anomalies were also detected, which were highly significant (P < 0.001) at 2 µg l−1. Embryonic development was greatly slowed at the highest TPT concentrations: embryos never reached the pluteus stage at 5 µg l−1, and development was blocked at the gastrula stage at 10 µg l−1. As observed in previous experiments using butyltin compounds, embryotoxic effects on both skeletal deposition and blocked development are presumed to be due to interference of TPT with intracellular calcium homeostasis. Sea urchin gametes are more sensitive to TPT than embryos, this condition emphasising the environmental risk due to TPT contamination. Copyright © 2002 John Wiley & Sons, Ltd.
Structure and in vitro antifungal activity of [2,6‐bis(dimethylaminomethyl)phenyl]diphenyltin(IV) compounds
Authors: Růžic̆ka Aleš , Dostál Libor , Jambor Roman , Buchta Vladimír , Brus Jir̆í , Císar̆ová Ivana , Holc̆apek Michal , Holec̆ek Jaroslav
Published: August 2002

A set of seven [2,6‐bis(dimethylaminomethyl)phenyl]diphenyltin(IV) ({[(CH3)2NCH2]2(C6H3)}­(C6H5)2Sn+X−) ionic organotin(IV) compounds (X = Br, NO3, CN, SCN, SeCN, BF4 and PF6) has been prepared and characterized by electrospray ionization mass spectrometry, 1H NMR spectroscopy in CDCl3,119Sn NMR in CDCl3 and DMSO‐d6 solution, as well as by 13C and 119Sn CP/MAS NMR spectroscopy and X‐ray diffraction techniques in the solid state. The in vitro antifungal activity of these water‐soluble ionic organotin(IV) compounds was compared with starting compounds and the antifungal drugs currently in clinical use. Copyright © 2002 John Wiley & Sons, Ltd.
D‐Glucuronate complexes of mono‐, di‐ and triorgano tin(IV) compounds: potentiometric and Mössbauer spectroscopic investigations
Authors: Fiore Tiziana , Foti Claudia , Gianguzza Antonio , Orecchio Santino , Pellerito Lorenzo
Published: August 2002

Complex species formation of glucuronate with mono‐, di‐ and trimethyltin(IV) cations has been studied potentiometrically in a wide range of ionic strength (0.1 to 1 mol l−1, NaCl medium), at 25 °C. By a suitable complex formation model, according to which all the interactions are considered, the formation constants at infinite dilution have been calculated by using a well‐tested equation for the ionic strength dependence. The following complex species have been found (R = CH3): [RSn(gluc)(OH)]+, [RSn(gluc)(OH)2]0 and [(RSn)2(gluc)(OH)5]0 for the monomethyltin(IV)–glucuronate system; [R2Sn(gluc)]+ and [R2Sn(gluc)(OH)]0 for the dimethyltin(IV)–glucuronate system; and [R3Sn(gluc)]0 for the trimethyltin(IV)–glucuronate system. Mössbauer investigations, carried out in quickly frozen solution, confirmed the species formation and led us to propose their structural configuration. Copyright © 2002 John Wiley & Sons, Ltd.
Microfocus small‐angle X‐ray scattering investigation of the skin–core microstructure of lyocell cellulose fibers
Authors: Moss C. E. , Butler M. F. , Müller M. , Cameron R. E.
Published: August 2002

Skin–core microstructures in hydrated lyocell cellulose fibers were investigated using microfocus small‐angle X‐ray scattering (SAXS). Both single fibers and fiber cross sections were observed. In all the fibers studied, a thin skin layer was observed in which the voids were smaller in cross section and better oriented than those in the core. The division between skin and core may not be sharp. A draw ratio of 0.80 gave fibers with voids that were shorter, larger in cross section, and more misoriented than the fibers produced with a draw ratio of 1.68. In contrast, there was little difference in void structure between samples coagulated in water and in 25% amine oxide aqueous solution. The results are explained in the context of the spinodal decomposition, which is thought to occur during coagulation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2799–2816, 2002; DOI 10.1002/app.10256
Surface crosslinking of high‐density polyethylene beads in a modified plasma reactor
Authors: Kim Jae Woo , Choi Ho Suk
Published: August 2002

High‐density polyethylene (HDPE) beads were successfully surface‐crosslinked in a modified plasma reactor. The modified plasma reactor treats large amounts of beads, which are uniformly surface‐crosslinked. In this study, effects of the gas pressure, radio‐frequency (RF) power, and the treatment time on the degree of surface crosslinking were systematically investigated. Degree of surface crosslinking was measured by solvent extraction method (boiling xylene method, BXM). The gel content of plasma‐treated HDPE increases from 0.0 to 1.05% within 10 min at 100 mTorr, 200 W. FTIR and DSC analyses show that the crosslinked layer after plasma treatment is limited only at HDPE surface without changing the bulk thermal property of HDPE. Through the analysis of FTIR, it was confirmed that main peaks corresponding to CH2 bands were decreased and two peaks corresponding to CF2 and CF3 were observed after plasma surface modification. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2921–2929, 2002; DOI 10.1002/app.10295
Synthesis and characterization of 4,5‐bis(4‐fluorobenzoyl)‐1‐methylcyclohexene and its polyethers
Authors: Gao Yan , Jian Xigao , Xuan Yingnan , Xu Zhiyong , Lü Qianjiang
Published: August 2002

A new difluoride 4,5‐bis(4‐fluorobenzoyl)‐1‐methylcyclohexene (DFKK) has been prepared with fumaryl chloride, fluorobenzene, and 2‐methyl‐1,3‐butadiene as starting materials through two steps of reactions. This DFKK monomer undergoes reaction with 2,2‐(p‐hydroxyphenyl)‐iso‐propane (BPA) in the presence of excess anhydrous potassium carbonate in sulfolane to give a high molecular weight reactive poly(ether ketone ketone) (PEKK) that is very soluble in solvents such as chloroform and N,N‐dimethylformamide at room temperature, has glass transition temperature of 182°C, and is easily cast into flexible and bale ivory film with tensile strength of 64 MPa. The 5% weight loss temperature is 407°C. Ring‐closing reaction of PEKK with hydrazine gives cyclized PEKK (CPEKK) with improved thermal stability and reduced solubility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1866–1871, 2002; DOI 10.1002/app.10454
Cut‐out filter for ultraviolet radiation from poly(vinyl alcohol)
Authors: Abd El‐Kader K. M. , El‐Lawindy A. Y. M. , Mansour A. F. , Abdel Hamied S. F.
Published: August 2002

The effects of ultraviolet (UV) radiation and thermal annealing on the optical and mechanical properties of polyvinyl alcohol (PVA) were studied. Pure PVA samples were prepared by casting technique. Xenon arc lamp was used to irradiate the sample. The irradiated PVA sample was heated at 150°C for 2 h. The optical and mechanical properties of original, irradiated, and irradiated and then heated samples were measured. The irradiated and then heated sample showed lower transmission in the wavelength range from 190 to 320 nm and the transmission was higher in the visible region than the original and irradiated samples. The stress–strain measurements were performed. Modulus of elasticity of the double‐treated sample was approximately four times higher than that of original sample. The obtained results show the possibility of using this sample as cut‐out filter for UV radiation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1295–1299, 2002; DOI 10.1002/app.10486
Manufacture of carbon fibers from polyacrylonitrile precursors treated with CoSO4
Authors: Zhang Wang Xi , Wang Yan Zhi
Published: August 2002

Free‐radical solution copolymerization of itaconic acid and acrylonitrile was carried out in DMSO using azodiisobutyronitrile as an initiator, changing the feed rate of itaconic acid. The resulting polymerization solution was spun to form polyacrylonitrile (PAN) precursors of carbon fibers. The precursors were treated with a CoSO4 aqueous solution on‐line. The structure and properties of untreated and treated PAN precursors and the resultant carbon fibers were characterized by SEM and TEM, a stabilization process, etc. It is suggested that CoSO4 acts as a catalyst in the formation of a ladder structure and reduces the temperature of cyclization, and the carbon fibers developed from treated PAN fibers showed improvement in the tensile strength and the Young's modulus. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 153–158, 2002
Interaction of different types of cells on physicochemically treated poly(L‐lactide‐co‐glycolide) surfaces
Authors: Khang Gilson , Choee Jong‐Hwa , Rhee John M. , Lee Hai Bang
Published: August 2002

To improve the cell compatibility of poly(L‐lactide‐co‐glycolide) (PLGA; 75/25 molar ratio of lactide to glycolide) surfaces, we experimented with physicochemical treatments. Chemical treatments employed 70% chloric acid, 50% sulfuric acid, and 0.5N sodium hydroxide solutions, and physical methods included corona and plasma treatments. The water contact angle of surface‐treated PLGA decreased from 73 to 50–60°; that is, the hydrophilicity increased because of the introduction of oxygen‐containing functional groups onto the PLGA backbone according to electron spectroscopy for chemical analysis. The physicochemically modified PLGA surfaces were used to investigate the interaction of four different types of cells—hepatoma (Hep G2), osteoblast (MG 63), bovine aortic endothelial (CPAE), and fibroblast (NIH/3T3) cells—in terms of the surface hydrophilicity and hydrophobicity of PLGA. The cells that adhered and grew on the physicochemically modified PLGA surfaces were counted and observed with scanning electron microscopy. The adhesion and growth of Hep G2, MG 63, CPAE, and NIH/3T3 cells on physicochemically treated PLGA surfaces, especially on chloric acid‐treated PLGA surfaces, were more active than on the control. This result seems closely related to the serum protein adsorption on the surface; the serum proteins were also adsorbed more on the hydrophilic surface. Surface hydrophilicity apparently plays an important role in cell adhesion, spreading, and growth on PLGA surfaces. The surface modification technique used in this study may be applicable to tissue engineering for the improvement of tissue compatibility of film‐ and scaffold‐type substrates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1253–1262, 2002
Studies of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. I. Influences of glycolysis conditions
Authors: Chen Cheng‐Ho , Chen Chuh‐Yean , Lo Yu‐Wen , Mao Ching‐Feng , Liao Wei‐Tung
Published: August 2002

The glycolysis of recycled poly(ethylene terephthalate) flakes by ethylene glycol (EG) is investigated. Bis‐2‐hydroxyethyl terephthalate (BHET) and oligomers are predominately glycolysis products. The influences of glycolysis temperature, glycolysis time, and the amount of catalyst (cobalt acetate) are illustrated. The BHET, dimer, and oligomers are predominately glycolysis products. The optimum glycolysis temperature is found to be 190°C. If a 190°C glycolysis temperature, 1.5‐h glycolysis time, and 0.002 mol glycolysis catalyst (cobalt acetate) are used, the glycolysis conversion is almost 100%. The glycolysis conversion rate increases significantly with the glycolysis temperature, glycolysis time, and the amount of cobalt acetate. Thermal analyses of glycolysis products are examined by differential scanning calorimetry. In addition, the chemical structures of glycolysis products are also determined by a Fourier transform IR spectrophotometer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 943–948, 2001
An analysis of capillary water behavior in poly‐p‐phenylenebenzobisoxazole fiber
Authors: Kitagawa Tooru , Yabuki Kazuyuki
Published: August 2002

This study concerns with analysis of water inside a poly‐p‐phenylenebenzobisoxazole (PBO) fiber. It is important to analyze the state of water attached to polymer, because it may affect properties of fibers as the increase of drying speed of water from the fiber. To carry out such observation, differential scanning calorimetry and nuclear magnetic resonance spectroscopy were applied. They reveal the large freezing point depression and the state of water inside wet PBO fiber. It shows extraordinary low crystallization temperature. The reason may be that the water is packed into capillary voids whose diameter is around 2–3 nm. Proton NMR analysis also suggests the above result. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1030–1036, 2001
Changes in structure of PA6 during processing
Authors: Jurkowski B. , Olkhov Y. A. , Kelar K. , Olkhova O. M.
Published: August 2002

Using thermomechanical analysis, the molecular weight distribution and relaxation transitions were investigated in commercial PA6 and in this polymer after passage through an extruder with a static mixer. A diblock or triblock amorphous structure and a crystalline portion in the studied PA6 were found. These amorphous structures differ in the glass transition temperatures by 80–180°C. There was a principal difference in the topological and molecular structures of PA6 depending on the processing conditions—number of cycles and shear rates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2361–2368, 2001
Starlike Nylon 6/polyurethane block copolymers by reaction injection‐molding process (RIM)
Authors: González‐De Los Santos Eduardo A. , López‐Rodríguez Angélica S. , Lozano‐González Ma. Josefina , Soriano‐Corral Florentino
Published: August 2002

Starlike block copolymers of Nylon‐6 and polyurethane were synthesized using ε‐caprolactam as a monomer, caprolactam magnesium bromide as a catalyst, and a star prepolymer of polyurethane. These copolymers were compared with the linear block copolymers of Nylon‐6 and polyurethane. Such copolymers were obtained using the reaction injection‐molding process (RIM) of ε‐caprolactam at different contents of polyurethane (5–30 wt %). In increasing the content of the soft phase, in FTIR, a displacement was observed in the band at 1637 cm−1, assigned to the amide I of the Nylon 6, to a higher wavenumber. This suggests a bigger interaction between the urethane group of the polyurethane and the amide group of the Nylon 6. Star block copolymers showed better mechanical properties compared with the linear ones. This behavior is attributed to the higher crystallinity and ramifications present in the materials. The structure and the thermal properties of the copolymers were studied using different techniques such as DSC, WAXS, DMA, and SEM. A decrease in the crystallinity when increasing the soft phase was also observed. Finally, physical tensile, impact, and hardness tests of the copolymers were carried out. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2483–2494, 2001
Design and synthesis of superabsorbent polymers
Authors: Raju M. Padmanabha , Raju K. Mohana
Published: August 2002

A series of novel copolymer superabsorbents based on the monomers acrylamide (AM), acrylic acid (AA), acrylonitrile, methacrylic acid, sodium acrylate (SA), and 2‐hydroxyethyl methacrylate (HEMA) were prepared by copolymerization using ammonium persulfate as an initiator and N,N‐methylenebisacrylamide as a crosslinking agent. The experimental results of superabsorbent polymers (SAPs) show that the absorbency in water and NaCl solutions is maximum for AM, SA, HEMA and AM, AA, SA combinations. The copolymers were characterized by IR spectroscopy. The water retention of soil was also enhanced using the above superabsorbents. Use of SAPs for the growth of the croton plant was also investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2635–2639, 2001
Crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends
Authors: Shi Yu , Jabarin Saleh A.
Published: August 2002

The crystallization kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were investigated by DSC as functions of crystallization temperature, blend composition, and PET and PEN source. Isothermal crystallization kinetics were evaluated in terms of the Avrami equation. The Avrami exponent (n) is different for PET, PEN, and the blends, indicating different crystallization mechanisms occurring in blends than those in pure PET and PEN. Activation energies of crystallization were calculated from the rate constants, using an Arrhenius‐type expression. Regime theory was used to elucidate the crystallization course of PET/PEN blends as well as that of unblended PET and PEN. The transition from regime II to regime III was clearly observed for each blend sample as the crystallization temperature was decreased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 23–37, 2001
Kinetic study of olefin polymerization with a supported metallocene catalyst. IV. Comparison of bridged and unbridged catalyst in gas phase
Authors: Chakravarti S. , Ray W. Harmon , Zhang Simon X.
Published: August 2002

A kinetic study of ethylene/1‐hexene (E/1‐H) copolymerization is conducted with a supported bridged metallocene catalyst in a gas phase reactor. The investigation into the kinetics of ethylene/1‐hexene copolymerization includes the effects of operational parameters such as the reaction temperature, pressure, and comonomer concentration. On‐line perturbation techniques are implemented to determine key kinetic parameters such as the activation energies for propagation and catalyst deactivation. A comparison of the kinetic parameters and behavior is made between the bridged and a previously studied unbridged catalyst. Finally, a two‐site model is proposed to explain the observed kinetic behavior with changing reaction temperature and comonomer concentration. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1451–1459, 2001
Oil shale solid waste recycling in the development of new silica fillers for elastomeric composites
Authors: Perruso Carlos Renato , Neto Arnaldo Alcover , Neumann Reiner , Nunes Regina Célia Reis , De Araújo Fonseca Marcus Vinícius , Nascimento Regina Sandra Veiga
Published: August 2002

The production of Brazilian shale oil gives rise to 6600 ton/day of a solid waste of retorted shale, and larger amounts of dolomitic waste rock are generated during mining. Two vitreous materials were obtained through the melting of different proportions of these two wastes. By leaching these materials with hydrochloric acid at 90°C, two different kinds of silicas (powder and gel, both amorphous) with specific surface areas reaching up to ∼ 420 m2/g were generated. These silicas were further modified through an Ostwald‐ripening type of treatment in ammonium hydroxide solution at 80°C. The process eliminated almost completely the deleterious micropores. The obtained silicas were evaluated as reinforcing fillers for SBR‐1502. The employment of one of the modified silicas gave rise to a composite with better mechanical properties than those displayed by the one with untreated silica. Scanning electronic microscopic observation disclosed the existence of great morphological differences between these silicas. Apparently, the aging treatment gave rise to the production of better anchoring sites for the elastomer molecules. NMR studies also showed the reduction of the silanol content of the treated silica. The fracture surface of the composite disclosed a good wetting of this silica by the elastomeric matrix. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2856–2867, 2001
Effects of hard‐segment compositions on properties of polyurethane–nitrolignin films
Authors: Zhang Lina , Huang Jin
Published: August 2002

Segmented polyurethane (PU) films from castor‐oil‐based PU prepolymer with different hard‐segment compositions and nitrolignin (NL) were synthesized. Diisocyanates (DIs), such as 2,4‐tolylene DI (TDI) and 4,4′‐diphenylmethane DI (MDI), 1,4‐butanediol (BDO) as a chain extender, and trimethanol propane (TMP) as a crosslinker were used to obtain PU films containing NL (UL) which were named as UL–TB for TDI and BDO, UL–TT for TDI and TMP, UL–MB for MDI and BDO, and UL–MT for MDI and TMP, respectively. The mechanical properties and thermal stability of the films were characterized by a tensile test and thermogravimetric analysis, respectively. The MDI‐based UL films exhibited a higher tensile strength (σb) and thermal stability than TDI‐based UL. However, the recoverability of the TDI‐based UL films was better than that of others. The UL films with TMP (UL–TT and UL–MT) had higher σb and lower breaking elongation (ϵb) than the UL films with BDO (UL–TB and UL–MB), caused by enhancement in the crosslinking network of hard segments and microphase separation between soft and hard segments. The values of σb and ϵb of the UL films that contained NL were much higher than those of the PU films, which indicates that the introduction of NL increased the interaction between hard segments by crosslinking. The hydrogen bonding in the UL films was studied by infrared spectroscopy, which indicated that MDI favored the formation of hydrogen bonds, especially in the ordered domain. Differential scanning calorimetry, dynamic mechanical analysis, and wide‐angle X‐ray diffraction indicated that the UL films were compatible as a whole, but microphase separation existed between soft and hard segments and significantly affected the mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3251–3259, 2001
Flow instability in capillary extrusion of plasticized poly(vinyl chloride)
Authors: Yamaguchi Masayuki
Published: August 2002

Flow instability in a capillary extrusion is studied for a high molecular weight, plasticized poly(vinyl chloride) (PVC). The onset of melt fracture correlates with the long time relaxation ascribed to the generation and/or growth of PVC crystallites. An increase in the residence time in the cylinder leads to this long time relaxation and results in the melt fracture, although the apparent shear stress remains constant, irrespective of the residence time. The extrudate temperature and the species of the plasticizer also have a significant influence on the apparatus of the extruded products. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1277–1283, 2001
Improvements of white pine wood properties by impregnation with unsaturated polyesters in admixture with styrene
Authors: Mahmoud A. A. , Eissa A. M. F. , Omar M. S. , El‐Sawy A. A. , Shaaban A. F.
Published: August 2002

Four unsaturated polyester resins based on poly(ethyleneglycol‐maleate‐phthalate) (PE) with different bromine contents were used for the impregnation and coating of oven‐dried white pine wood samples in admixture with styrene (St). Curing was affected by the initiator–heat technique by using 0.2 wt % of benzoyl peroxide (Bz2O2). It was found that the use of the four prepared unsaturated polyester/styrene (PE/St) mixtures resulted in the formation of wood plastic combinations (WPC) with a higher percentage retention, higher percentage crosslinking, water repellent effectiveness, and antiswelling efficiency. ASE properties are excellent for wood samples impregnated with resin without bromine. Water absorption was decreased and a good water uptake was obtained by wood samples impregnated by resin of lower bromine content. Compressive strength was increased for all samples, especially for the wood samples impregnated with resin without bromine. The flammability test for the prepared plastics showed that the samples without bromine are classified as burning substance and the other three samples contain bromine are classified as self‐extinguishing samples from ASTM D635‐68T (1956). On the other hand, impregnated wood samples with PE/St mixtures show no fire retardancy after carrying ASTM E160‐50 (1965), whereas coated wood samples with the same mixtures show excellent fire‐retarding properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1410–1416, 2001
Dielectric spectroscopy of conductive polyaniline salt films
Authors: Han Moon Gyu , Im Seung Soon
Published: August 2002

Dielectric responses of polyaniline (PANI) salt films, made from two different methods, were compared to investigate the effect of a dopant and film‐formation methods on the dielectric properties. One of the film‐formation methods for emeraldine salt was the film‐doping method, and the other, the solution‐doping method. The conductivity relaxation and dielectric properties were measured by a microdielectrometer at 293 K in the frequency range of 1–100,000 Hz. Dielectric spectra were a function of the dopant in the case of the film‐doping method, whereas it was a function of solvent–dopant combinations as well as the dopants in the solution‐doping method. The dielectric responses of film‐doped samples had similar patterns irrespective of the dopants, while those of solution‐doped samples were varied, probably due to different conjugation conditions or/and the conduction mechanism. In the case of film‐doped samples, dielectric loss and permittivity values were increased with decreasing dopant sizes. The dielectric relaxation times were also varied depending on the kind of dopants. The different solvent–dopant combinations led to variation of the dielectric responses in the solution‐doped PANI due to an altered chain structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2760–2769, 2001
Absorption and desorption of liquid water by a superabsorbent polymer: Effect of polymer in the drying of the soil and the quality of certain plants
Authors: Bakass M. , Mokhlisse A. , Lallemant M.
Published: August 2002

In this work, we were interested in the study of the kinetic behavior of the reaction of drying soil representing the Marrakesh region (south of Morocco) in the presence of an superabsorbent polymer. The presence of a polymer in the soil diminished the kinetic drying of the soil, which will have as an application a reduction in water loss in the process of irrigation. The presence of a polymer in the soil enables a complete modification of the kinetic regimes controlling the soil‐drying kinetic. We also realized the first study of the behavior of certain selected plants in the melange of a soil and a polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 234–243, 2002
Formation and structure of high mechanical performance fibers. II. Flexible polymers
Authors: Kikutani Takeshi
Published: August 2002

Conditions for the formation of high performance fibers from flexible and semi‐flexible polymers are reviewed in terms of the chemical structure, chain conformation, super structure, and modeling. Small cross‐sectional area and extended conformation are important factors for designing the high‐performance polymers. Tensile modulus decreases significantly by only a small contraction of main chain from the planar zigzag conformation. Model calculation for the estimation of the ultimate tensile strength includes the evaluations of bond strength and the kinetic theory for rupture of primary and secondary bonds. Presence of defects such as chain ends are also considered. Macroscopic defects can be evaluated based on Griffith's theory. Drawability, which is important for the production of high performance fibers, can be improved through the control of entanglement. Experimental and industrial procedures for the production of high performance fibers such as gel spinning of polyethylene, pressurized drawing of polyoxymethylene, controlled shrinkage and drawing of polytetrafluoroethylene, and solid state co‐extrusion of high molecular weight poly(ethylene terephthalate) are also reviewed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 559–571, 2002
Does electrofishing harm freshwater pearl mussels?
Authors: Hastie Lee C. , Boon Philip J.
Published: August 2002

1. Two experiments were carried out in a Scottish river to test the effects of electrofishing on endangered freshwater pearl mussels (Margaritifera margaritifera).

2. In the first experiment, two areas of mussel bed were marked out as treatment and control sites and the former was electrofished using standard equipment. The mussels were examined 10 min, 24 h and 35 days after treatment and their shell valve closure responses, burrowing capabilities and gravidities were recorded as signs of normal ‘functioning’.

3. In the second experiment, individual mussels were marked as treatments and controls and the former were electrofished. These mussels were examined as before.

4. No mortalities occurred and no significant differences in ‘functioning’ between treatments and controls were observed in either experiment.

5. Since no measurable treatment effect could be demonstrated, it appears that electrofishing did not adversely affect the short‐term survival of M. margaritifera. Copyright © 2001 John Wiley & Sons, Ltd.
Assessing adult Trichoptera communities of small streams: a case study from Charnwood Forest, Leicestershire, UK
Authors: Greenwood M.T. , Bickerton M.A. , Petts G.E.
Published: August 2002

1. Adult caddisflies were collected using non‐attracting Malaise traps at four sites on a small headwater stream from May to November 1990. Sites S1 and S2 were most natural and upstream of a reservoir; where S3 was located in the bypass channel, and S4, downstream.

2. The flight period for each species is recorded to provide baseline data. Flight activity patterns fall into two groupings: (a) species with a flight activity of 3–4 months, and (b) those species with a short flight period of up to 6 weeks.

3. Sixty‐one species from 15 families were collected, including the endangered Red Data Book species Tinodes pallidulus McLachlan.

4. Significant differences in community parameters are shown among all sites, many species apparently having local catchment areas. The influence of artificial habitats, the open bypass channel and adjacent reservoir, is clearly demonstrated.

5. The data illustrate the potential of using adult caddisflies in conservation assessment of small streams. Working with adults is taxonomically rigorous and they are useful bioindicators of the environmental quality of the valley floor corridor. Copyright © 2001 John Wiley & Sons, Ltd.
Cellular events at the onset of physiological root resorption in rabbit deciduous teeth
Authors: Sahara Noriyuki
Published: August 2002

For elucidation of how physiological root resorption of deciduous teeth is initiated, the cellular events that occur surrounding the root of rabbit deciduous teeth before and at the onset of physiological root resorption were observed by means of light and electron microscopy. In addition, the cytodifferentiation of odontoclasts during the initial phase of this root resorption was evaluated by histochemical staining of tartrate‐resistant acid phosphatase (TRAP) activity as a marker odontoclasts and their precursors. The present investigation was focused on the physiological root resorption of the deciduous lower second molar of rabbits from Day 0–5 postnatally. At birth, the deciduous molar had not erupted yet, and no TRAP‐positive cell could be found surrounding the tissue adjacent to the root of the deciduous tooth. TRAP‐positive mononuclear cells were initially detected in the coronal portion of the dental follicle of the permanent tooth at Day 1 postnatally. Ultrastructurally, these mononuclear cells had moderate numbers of mitochondria and short‐strand rough endoplasmic reticulum, as well as scattered free ribosomes throughout their cytoplasm. TRAP‐positive mononuclear cells then appeared in the cementoblast layer immediately adjacent to the surface of the deciduous roots. These mononuclear cells projected cytoplasmic extensions between the cementoblasts and made contact with the cementum. At that time, cell–cell contact was frequently observed between these mononuclear cells and cementoblasts. During 3–5 days postnatally, the number of TRAP‐positive multinucleate odontoclasts on the root surface gradually increased. They had well‐developed ruffled borders and made typical resorption lacunae on the root surface of the deciduous tooth. During this early postnatal period, neither inflammatory cells nor necrotic tissue could be observed surrounding the deciduous root. This study demonstrates that the dental follicle of the permanent tooth as well as the connective tissue adjacent to the deciduous root might play important role in site‐ and time‐specific recruitment, development, and activation of odontoclasts before and at the onset of physiological root resorption. Anat Rec 264:387–396, 2001. © 2001 Wiley‐Liss, Inc.
Developmental pattern of ANF gene expression reveals a strict localization of cardiac chamber formation in chicken
Authors: Houweling Arjan C. , Somi Semir , Van Den Hoff Maurice J.B. , Moorman Antoon F.M. , Christoffels Vincent M.
Published: August 2002

In mouse, atrial natriuretic factor (ANF) gene expression was shown to be a marker for chamber formation within the embryonic heart. To gain insight into the process of chamber formation in the chicken embryonic heart, we analyzed the expression pattern of cANF during development. We found cANF to be specifically expressed in the myocardium of the morphologically distinguishable atrial and ventricular chambers, similar to ANF in mouse. cANF expression was never detected in the myocardium of the atrioventricular canal (AVC), inner curvature, and outflow tract (OFT), which is lined by endocardial cushions. Expression was strictly excluded from the interventricular myocardium and most proximal part of the bundle branches, as identified by the expression of Msx‐2, whereas the rest of the bundle branches, trabeculae, and surrounding working myocardium did express cANF. The myocardium that forms de novo within the cushions after looping did not express cANF. At HH9 cANF expression was first observed in a subset of cardiomyocytes, which was localized ventrally in the fused heart tube and laterally in the unfused cardiac sheets. Together, these results show that cANF expression can be used to distinguish differentiated chamber (working) myocardium, including the peripheral ventricular conduction system, from embryonic myocardium. We conclude that differentiation of chamber myocardium takes place already at HH9 at the ventral side of the linear heart tube, possibly preceded by latero‐medial signals in the unfused cardiac sheets. Anat Rec 266:93–102, 2002. © 2002 Wiley‐Liss, Inc.
Kidney of giraffes
Authors: Maluf N.S.R.
Published: August 2002

This study focuses on certain aspects of the renal structure of the giraffe, with some implications as to its function. About 4,000 collecting ducts open at the truncated end of a curved crest that juts into the renal pelvis as the inner medulla (IM). Extensions of the pelvis pass between the medullary (MP) and vascular (VP) processes almost to the corticomedullary border. The MPs contain an IM and an outer medulla (OM) containing clusters of capillaries (vascular bundles). The VPs contain the interlobar arteries and veins. All of the IM and almost all of the OM, with its vascular bundles, are bathed with pelvic urine. The cortex comprises 63% of the parenchyma. The OM has nine times the mass of the IM. The IM comprises 4% of the parenchyma. The ratio of mass of the adult cortex to the medulla is 1.7:1.0, and the number of glomeruli per kidney is 6.6 × 106. Glomerular mass is 6.2–6.7% of renal mass in the adult and 5.2% in the 6‐month‐old calf. The dimensions of the glomerular capsules are the same across the thickness of the cortex. Every terminal collecting duct drains an estimated 1,650 nephrons. In the adult giraffe the ratio of thickness of the muscularis of the main renal artery (RA) to its diameter is 0.117 (right RA) and 0.132 (left RA). These ratios are close to those in rhinoceros and ox but greater than in man. The visceral arteries (celiac, anterior mesenteric, and renal) have about the same muscularis : diameter ratio. Giraffes have arterial hypertension, but atherosclerosis is apparently absent and serum lipid fractions are low. Anat Rec 267:94–111, 2002. © 2002 Wiley‐Liss, Inc.
New fossil hominid calvaria from Indonesia—Sambungmacan 3
Authors: Márquez Samuel , Mowbray Kenneth , Sawyer G J , Jacob Teuku , Silvers Adam
Published: August 2002

A morphologically distinct partial calvaria of Homo cf. erectus from Java, Indonesia is described. The fossil hominid Sambungmacan 3 (Sm 3) was first discovered in 1977 from the banks of the Solo River near the village of Poloyo, Sambungmacan district, in central Java. It was later recovered in a New York City natural history establishment in 1999 and quickly returned to the Indonesian authorities. Examination of Sm 3 shows that the calvaria is well preserved with only portions of the cranial base missing. The most striking characteristics of Sm 3 include: the presence of a vertically rising forehead, more open occipital/nuchal and frontal angles, a more globular vault, and a cranial capacity within the Homo erectus range. Most notably absent in Sm 3 are a number of the classic characters attributed to Homo erectus, such as a strongly expressed angular torus and a continuous supratoral sulcus. The absence of such characters would normally place the calvaria outside the range of Homo erectus (sensu stricto), however, overall quantitative and qualitative morphological assessments of Sm 3 place it within the Homo erectus spectrum. The combination of the morphological characters in Sm 3 may be interpreted in several ways: 1.) the known cranial variation of H. erectus from Indonesia and China is extended; 2.) this calvaria shows evidence of evolutionary change within H. erectus; or 3.) more than one species of Homo existed in the (presumed) Middle Pleistocene of Java.) Anat Rec 262:344–368, 2001. © 2001 Wiley‐Liss, Inc.
Compartmentalization of proteinases and amylases in Nauphoeta cinerea midgut
Authors: Elpidina Elena N. , Vinokurov Konstantin S. , Gromenko Viktor A. , Rudenskaya Yuliya A. , Dunaevsky Yakov E. , Zhuzhikov Dmitry P.
Published: August 2002

Compartmentalization of proteinases, amylases, and pH in the midgut of Nauphoeta cinerea Oliv. (Blattoptera:Blaberidae) was studied in order to understand the organization of protein and starch digestion. Total proteolytic activity measured with azocasein was maximal at pH 11.5 both in anterior (AM) and posterior (PM) halves of the midgut, but the bulk of activity (67%) was found in PM. Total AM and PM preparations were fractionated on a Sephadex G‐50 column and further analysed by means of activity electrophoresis and specific inhibitors and activators. The major activity in PM was classified as an unusual SH‐dependent proteinase with Mr 24,000 and pH optimum with synthetic substrate BApNA at 10.0. The enzyme was 43‐fold activated in the presence of 1 mM DTT, insensitive to synthetic inhibitors of serine (PMSF, TLCK, TPCK) and cysteine (IAA, E‐64) proteinases, strongly inhibited by STI, and displayed four active bands on zymograms. In PM, activities of trypsin‐like, chymotrypsin‐like, subtilisin‐like, and cysteine proteinases were observed. Aspartic and metalloproteinases were not detected. In AM, activity of unusual SH‐dependent proteinase also dominated and activity of chymotrypsin‐like proteinase was observed, but their levels were much lower than in PM. Distribution of amylase activity, exhibiting an optimum at pH 6.0, was quite the opposite. The major part of it (67%) was located in AM. Treatment of amylase preparation with proteinases from AM and PM reduced amylase activity twofold. pH of the midgut contents was 6.0–7.2 in AM, 6.4–7.6 in the first and 8.8–9.3 in the second halves of PM. Thus, pH in AM is in good agreement with the optimal pH of amylase, located in this compartment, but the activity of proteinases, including the ability to degrade amylase, in such an environment is low. Active proteolysis takes place in the second half of PM, where pH of the gut is close to the optimal pH of proteinases. Arch. Insect Biochem. Physiol. 48:206–216, 2001. © 2001 Wiley‐Liss, Inc.
Purification and characterization of biliverdin‐binding vitellogenin from the hemolymph of the common cutworm, Spodoptera litura
Authors: Maruta Kousei , Yoshiga Toyoshi , Katagiri Chihiro , Ochiai Masanori , Tojo Sumio
Published: August 2002

Biliverdin‐binding vitellogenin (Vg) was purified from adult female hemolymph of the common cutworm, Spodoptera litura, by using gel filtration and ion exchange chromatographies. The molecular mass of the protein was 490 kDa and it was composed of two 188‐kDa subunits. Three internal amino acid sequences obtained by digestion of the protein with lysylendopeptidase showed high similarity to those of Bombyx mori Vg, supporting the purified blue protein to be vitellogenin. Iatroscan analyses demonstrated the presence of biliverdin in Vg that occupied 2.4% of total lipid components. Among the lipids of Vg (9.5 μg total lipids per 100 μg protein), diacylglycerol was the most predominant, followed by phospholipid, hydrocarbons, and then triacylglycerol, while in biliverdin‐binding proteins (BPs) purified from larval hemolymph (3.1 μg total lipids per 100 μg protein), phospholipid was the most abundant lipid followed by diacylglycerol; hydrocarbons and triacylglycerol were minor components. Vg was first detected in the hemolymph of female pupae one day before eclosion, but injection of 5 μg of methoprene into a 3‐day‐old pupa induced Vg in the hemolymph 4 days earlier than in the control. Methoprene also induced a faster decline in BP‐A and BP‐B titers in the hemolymph with a corresponding increase of the Vg titer. These results suggest that juvenile hormone (JH) induces not only vitellogenesis but also the uptake of these proteins by stimulating the metamorphosis of fat body during the pupal stage. Arch. Insect Biochem. Physiol. 50:97–106, 2002. © 2002 Wiley‐Liss, Inc.
Archaeological site investigation by geoelectrical measurements in Tel‐Halawi (northern Syria)
Authors: Chouker Faris
Published: August 2002

About 100 vertical electrical soundings (VES) were made at Tel‐Halawi hill on the left bank of the Euphrates just before it flows into the Assad Lake in northern Syria. The VES stations were distributed, at 2 m spacing, along nine profiles (10 m apart), covering the southern part of the site. The electrode array adopted was a modified Schlumberger configuration (pole–dipole array with the B‐electrode placed far enough to be of negligible effect). During every sounding potential electrodes (MN) were fixed symmetrically on both sides of VES point location O (MO = ON = 0.25 m), whereas the current electrode A was moved away with the following distances from the MN midpoint: OA = 1, 1.5, 2, 3, 4, 5, 7 and 10 m.

The resistivity data measured were then treated and plotted in the field as resistivity cross‐sections of different pseudodepths, showing the specific influence of the buried targets at different depths. This procedure, although time consuming, looks a very promising technique for discovering near‐surface targets through resistivity survey. This method reflects successively the resistivity contribution of the buried targets according to their depth, separating them with regard to the depth of burial. It offers also higher reliability of results, owing to the confirmed response of buried targets as related multiple anomalies on several resistivity cross‐sections with gradually increasing depths. Many of these anomalies measured along the resistivity profiles were verified through excavation work. Copyright © 2001 John Wiley & Sons, Ltd.
A genetic attack on the defense complex
Authors: Gibson Greg
Published: August 2002

An increasing number of “non‐model” organisms are becoming accessible to genetic analysis in the field, as evolutionary biologists develop dense molecular genetic maps. Peichel et al.'s recent study1 provides a microsatellite‐based map for threespine stickleback fish (Gasterosteus aculeatus), and the first evidence for QTL affecting feeding morphology and defensive armor. This species has undergone rapid and parallel morphological and behavioral evolution, and there is now hope that some of the genes responsible for the divergence may soon be identified. BioEssays 24:487–489, 2002. © 2002 Wiley Periodicals, Inc.
Conformational studies of Lewis X and Lewis A trisaccharides using NMR residual dipolar couplings
Authors: Azurmendi Hugo F. , Martin‐Pastor Manuel , Bush C.Allen
Published: August 2002

The conformations of the histo‐blood group carbohydrate antigens Lewis X (Lex) and Lewis A (Lea) were studied by NMR measurements of one‐bond C—H residual dipolar couplings in partially oriented liquid crystal solutions. A strategy for rapid calculation of the difference between theoretical and experimental dipolar couplings of a large number of model structures generated by computer simulations was developed, resulting in an accurate model structure for the compounds. Monte Carlo simulations were used to generate models for the trisaccharides, and orientations of each model were sought that could reproduce the experimental residual dipolar coupling values. For both, Lea and Lex, single low energy models giving excellent agreement with experiment were found, implying a compact rigidly folded conformation for both trisaccharides. The new approach was also applied to the pentasaccharides lacto‐N‐fucopentaose 2 (LNF‐2) and lacto‐N‐fucopentaose 3 (LNF‐3) proving its consistency and robustness. For describing the conformation of tightly folded oligosaccharides, a definition for characterization of ring planes in pyranoside chairs is proposed and applied to the analysis of the relation between the fucose and galactose residues in the epitopes, revealing the structural similarity between them. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 89–98, 2002