bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, characterization, reactivity ratios by nuclear magnetic resonance spectroscopy, and application of (2,5‐Dichlorophenyl acrylate‐co‐glycidyl methacrylate) polymers as adhesives for the leather industry
Authors: Vijayaraghavan P. G. , Reddy B. S. R.
Published: November 2005

2,5‐ Dichlorophenyl acrylate (DPA)‐co‐glycidyl methacrylate (GMA) polymers having five different compositions were synthesized in 1,4‐dioxane using benzoyl peroxide as a free‐radical initiator at 70 ± 0.5°C. Using 1H‐NMR spectroscopy, the composition of the two monomers in the copolymers was calculated by comparing the integral values of the aromatic and aliphatic proton peaks. The reactivity ratios were calculated by Fineman–Ross (r1 = 0.31 and r2 = 1.08), Kelen–Tudos (r1 = 0.40 and r2 = 1.15), and extended Kelen–Tudos (r1 = 0.39 and r2 = 1.16) methods. The nonlinear error‐in‐variables model was used to compare the reactivity ratios. The copolymers were characterized by 1H and proton decoupled 13C‐NMR spectroscopes. Gel permeation chromatography was performed for estimating the Mw and Mn and Mw/Mn of the poly(DPA) and copolymers (DPA‐co‐GMA: 09 : 91 and 50 : 50). Thermal stability of the homo‐ and copolymers was estimated using TGA [poly(DPA) > DPA‐co‐GMA (50 : 50) > DPA‐co‐GMA (09:91)], while DSC was utilized for determining the glass transition temperature. Tg increased with increased DPA content in the copolymer. The 50 : 50 mol % copolymer was chosen for curing with diethanolamine in chloroform. The cured resins were tested for the adhesive properties on leather at different temperatures (50, 90, 100, and 110°C). The resin cured at 50 °C exhibited a maximum peel strength of 1.6 N/mm, revealing a good adhesive behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1167–1174, 2006
Preparation of novel MgCl2‐adduct supported spherical Ziegler–Natta catalyst for α‐olefin polymerization
Authors: Wang Li , Yu Hao‐Jie , Ma Zhen‐Li , Ye Zhao‐Yang , Jiang Shan , Feng Lian‐Fang , Gu Xue‐Ping
Published: November 2005

In this article, preparation of novel MgCl2‐adduct supported spherical Ziegler–Natta catalyst for α‐olefin polymerization is reported. The factors affecting the particle size (PS) and particle size distribution (PSD) of the prepared support were investigated. In this method, the internal donor added while preparing MgCl2‐adduct support was supposed to act as a crosslinking agent. Therefore it provided a reasonable way to enhance the morphology and control the PS of the resultant polymer particles. The possible mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 945–948, 2006
Characterization of three‐dimensional braided polyethylene fiber–PMMA composites and influence of fiber surface treatment
Authors: Wan Y. Z. , Luo H. L. , Wang Y. L. , Raman S. , Huang Y. , Zhang T. L. , Liu H.
Published: November 2005

Three‐dimensional (3D) braided polyethylene (PE) fiber‐reinforced poly(methyl methacrylate) (PMMA), denoted as PE3D/PMMA, composites were prepared. Mechanical properties including flexural and impact properties, and wear resistance were tested and compared with those of the corresponding unidirectional PE fiber–PMMA (abbreviated to PEL/PMMA) composites. Both untreated and chromic acid‐treated PE fibers were used to fabricate the 3D composites in an attempt to assess the effect of chromic acid treatment on the mechanical properties of the composites. Relative changes of mechanical properties caused by fiber surface treatment were compared between the PE3D/PMMA and PEL/PMMA composites. The treated and untreated PE fibers were observed by scanning electron microscopy (SEM) and analyzed by X‐ray photoelectron spectroscope (XPS). SEM observations found that micro‐pits were created and that deeper and wider grooves were noted on the surfaces of the PE fibers. XPS analysis revealed that more hydroxyl (OH) and carboxyl (COOH) groups were formed after surface treatment. The physical and chemical changes on the surfaces of the PE fibers were responsible for the variations of the mechanical properties of the PE/PMMA composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 949–956, 2006
Reinforcing effect of silica on the properties of styrene butadiene rubber–reclaim rubber blend system
Authors: De Debapriya , Das Amit , De Debasish , Panda Prabir Kumar , Dey Brojendranath , Roy Bidhan Chandra
Published: November 2005

Incorporation of silica into styrene butadiene rubber (SBR)–reclaim rubber (RR) blend system was carried out by sol–gel technique and conventional method. A well known silica coupling agent bis(3‐triethoxysilyl propyl) tetrasulfide was found to affect the curing characteristics and mechanical properties of SBR/RR vulcanizate. Here, the effect of RR on silica reinforcement was studied for different SBR/RR blend system. Silica incorporation by conventional mechanical mixing in absence of TESPT showed a much higher tensile properties than that of silica incorporated by the in situ sol–gel reaction of tetraethoxy silane both in presence and absence of TESPT. Studies of equilibrium swelling in a hydrocarbon solvent were also carried out. ATR study indicates that RR forms bond with silica particles due to the presence of active functional site on RR. The amount of silica incorporated by sol–gel reaction was determined through thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the silica filled SBR/RR vulcanizate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 957–968, 2006
Curie temperature of a ferromagnetic polymer chain model
Authors: Huang Jian‐Hua , Luo Meng‐Bo , Qian Chang‐Ji
Published: November 2005

Phase transition of a self‐avoiding walking polymer chain with spatial nearest neighbor ferromagnetic Ising interaction on the simple cubic lattice is investigated using Metropolis dynamic Monte Carlo technique. Magnetic susceptibility χ is determined from the Brillouin function and from the linear response of magnetization to external magnetic field in small field region. We find the later is better, though both are in consistent with each other at high temperatures. The magnetic susceptibility χ can be expressed using the Curie law and thus the Curie temperature θ is estimated. The chain length dependent Curie temperature θ of the chain model can be well fitted as θ = 1.40 − 4.0 ×n−0.619based on the finite‐size scaling law. The transition temperature for an infinite long chain θ(∞) = 1.40J/kBand the exponent ϕ = 0.619 are in agreement with our previous study (J Chem Phys 2003, 119, 2439). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 969–973, 2006
Addition‐curable propargyl‐containing novolac‐type phenolic resin: Its synthesis, characterization, cure, and thermal properties
Authors: Wang Mingcun , Wei Liuhe , Zhao Tong
Published: November 2005

In this article, propargyl functionalized novolac resins (PN resins), with varying propargyl contents and varying molecular weights, were synthesized conveniently. The structural characteristics were determined by 1HNMR and FTIR methods. Thermal cure studies revealed that the uncatalyzed thermal cure was remarkably affected by propargyl extent, while it was hardly affected by molecular weight. The processability of the as‐prepared PN resins was excellent as matrix of composite materials. The cure mechanism was complicated; postcure at high temperature was required to achieve entire crosslink formation. Both dynamic mechanical analysis and thermogravimetric analysis showed that the cured PN resins had substantially improved thermal mechanical properties and thermal stability in comparison to conventional cured phenolics. High propargyl extent was preferred for high thermal stability. The results show that PN resin is one of the ideal candidates for advanced composites matrices in thermostructural and ablative applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1010–1017, 2006
Structure and properties of polycarbosilane synthesized from polydimethylsilane under high pressure
Authors: Cheng Xiangzhen , Xie Zhengfang , Song Yongcai , Xiao Jiayu , Wang Yingde
Published: November 2005

The polycarbosilane (PCS), which is the precursor of SiC fiber, was synthesized under high pressure by thermal decomposition of polydimethylsilane. The composition, structure, and properties of the PCS were characterized by the measurements of softening point, elemental analysis, IR, GPC, NMR, TG‐DTG‐DTA, XRD, and oxidative reaction activity, respectively. Structure model of the PCS was therefore inferred. The results showed that the PCS was the polymer with a SiC backbone with Mn about 1587. IR and NMR showed the presence of SiC4 and SiC3H structure units containing SiCH3, SiCH2Si, and SiH groups. The ratio between H in CH bond and H in SiH bond was about 8.84 with SiC3H/SiC4 and about 0.51 from 1H NMR and 29Si NMR, respectively. Elemental analysis gave an empirical formula of SiC1.87H7.13O0.03. TG analysis showed that the ceramic yield of the PCS at 1200°C in a N2 flow was about 78.9%. β‐SiC microcrystal could be obtained when PCS was pyrolyzed at 1250°C with the crystal size about 37.5 Å. Compared with the PCS with similar softening point synthesized under normal pressure, the PCS synthesized under high pressure had approximate elemental composition, higher SiH bond content and reaction activity, higher molecular weight, and higher ceramic yield, but lower ratio of SiC3H and SiC4. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1188–1194, 2006
Microstructure and fracture behavior of polypropylene/barium sulfate composites
Authors: Wang Ke , Wu Jingshen , Zeng Hanmin
Published: November 2005

The microstructure, mechanical properties, and fracture behavior of polypropylene (PP)/barium sulfate (BaSO4) composites were studied. Four composite samples with different PP‐BaSO4 interface were prepared by treating the filler with different modifiers. The fracture behavior of the composites under different strain rates was studied by means of Charpy impact tests and essential work of fracture (EWF) tests. It is shown that a moderate interfacial adhesion is favorable for toughening, which ensures that the particles transfer the stress and stabilizes the cracks at the primary stage of the deformation, and satisfies the stress conditions of plastic deformation for matrix ligaments subsequently via debonding. Very strong interfacial adhesion is not favorable for toughness, especially under high strain rate, because the debonding‐cavitation process may be delayed and the plastic deformation of matrix may be restrained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1207–1213, 2006
Novel polyurethane insulating coatings based on polyhydroxyl compounds, derived from glycolysed PET and castor oil
Authors: Yeganeh Hamid , Shamekhi Mohammad Amin
Published: November 2005

To prepare versatile polyurethane material suitable as insulating coatings, novel kinds of polyhydroxy compounds (PHCs) were prepared via transesterification reaction of poly(ethylene terphthalate), different molecular weight of poly(ethylene glycol)s (PEGs), and castor oil. The final networks were prepared via crosslinking of PHCs with a novel blocked isocyanate curing agent (BPI) made from trimethylol propane (TMP), toluene diisocyanate (TDI), and N‐methyl aniline (NMA). Polyols and curing agent were characterized by conventional methods and the curing condition was optimized via gel content measurements. Curing kinetic of the polyurethane network formation was investigated by differential scanning calorimetric method and the kinetic parameters were derived. Crosslink density of the samples was determined via equilibrium swelling method and by using Flory‐Rehner equations. Effects of crosslink density on electrical, physical, mechanical, and dynamic mechanical (DMTA) properties of the polyurethane coatings were investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1222–1233, 2006
Phase reversal during water dispersion of polyurethane anionomer
Authors: Dang Xiaorong , Yuan Qiaolong , Fang Jiezhu , Wang Dening
Published: November 2005

A series of polyurethane anionomers (PUas) was synthesized from isophorone diisocyanate, polyneopentanediol adipate (P756), and hydrophilic dimethanol propionic acid (DMPA). The variation of electric conductivity and viscosity of such anionomers during water dispersion was followed. The results showed that the average diameter and polyindex of particles were reduced, the viscosity of dispersion was lowered, the time necessary for phase reversal became shorter, if the amount of DMPA or the temperature, at which the water dispersion was carried out, increased. DSC test revealed that the order of hard segments was disturbed after water dispersion. IR spectra demonstrated that, after the chain extender ethyl diamine was added into the PUa dispersion, the hydrogen bonding of NH with carbonyls was stronger, if the dispersion temperature and the mass fraction of DMPA increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1234–1239, 2006
High performance wood composites from highly filled polybenzoxazine
Authors: Rimdusit Sarawut , Tanthapanichakoon Wiwut , Jubsilp Chanchira
Published: November 2005

Highly filled systems prepared by compression molding of Hevea brasiliensis woodflour filled polybenzoxazine composites with high mechanical properties and reduced water uptake has been developed. The effects of percent filler content and particle size of woodflour on the obtained composite's properties were examined. The low melt viscosity of BA‐a type polybenzoxazine allows substantial amount of woodflour to be easily incorporated into the composites. The results showed that mechanical properties from dynamic mechanical analysis and flexural test at filler content below the optimum filler packing show approximately linear relationship with filler loading. The outstanding compatibility between the woodflour and the polybenzoxazine matrix is evidently seen from the large improvement in the composite's Tg and char yield. Scanning electron micrographs of the composite also reveals substantially strong interface between the woodflour filler and the polybenzoxazine matrix. Water absorption of the composites is greatly reduced with increasing the amount of polybenzoxazine due to the inherent low water absorption of the matrix. The polybenzoxazine is; therefore, a highly attractive candidate as high performance lignocellulosic binder or adhesive and other related applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1240–1253, 2006
Chain‐linked lactic acid polymers by benzene diisocyanate
Authors: Ren Jie , Wang Qin‐Feng , Gu Shu‐Ying , Zhang Nai‐Wen , Ren Tian‐Bin
Published: November 2005

Chain‐linked lactic acid polymers with high molecular weight were synthesized by two‐step polymerization method, including polycondensation and chain extending reactions. The effects of chain extender toluene diisocyanate (TDI) on the chain‐linked lactic acid polymers were studied. The polymers obtained were characterized by gel permeation chromatography, fourier transform infrared spectroscopy, 1H NMR, and differential scanning calorimeter. Reactions between 1,4‐butanediol and lactic acid oligomers led to hydroxyl‐terminated prepolymer, which provided significant increase of molecular weight in the chain extending reaction. In addition, the glass transition temperature (Tg) and the melting temperature (Tm) were increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1045–1049, 2006
Effect of fiber surface treatment on the properties of biocomposites from nonwoven industrial hemp fiber mats and unsaturated polyester resin
Authors: Mehta Geeta , Drzal Lawrence T. , Mohanty Amar K. , Misra Manjusri
Published: November 2005

Biocomposites were made with nonwoven hemp mats and unsaturated polyester resin (UPE). The hemp fiber volume fraction was optimized by mechanical testing. The effect of four surface treatments of industrial hemp fibers on mechanical and thermal properties of biocomposites was studied. The treatments done were alkali treatment, silane treatment, UPE (matrix) treatment, and acrylonitrile treatment. Bending strength, modulus of elasticity, tensile strength, tensile modulus, impact strength, storage modulus, loss modulus, and tan δ were evaluated and compared for all composites. The mechanical as well as thermal properties of the biocomposites improved after surface treatments. The properties of the above biocomposites were also compared with E‐glass–mat composite. To achieve balance in properties, a hybrid composite of industrial hemp and glass fibers was made. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1055–1068, 2006
Cure characteristics, morphology, mechanical properties, and aging characteristics of silicone rubber/ethylene vinyl acetate blends
Authors: Ganesh B. , Unnikrishnan G.
Published: November 2005

Silicone rubber/ethylene vinyl acetate (SR/EVA) rubber mixes with different ratios were prepared by using dicumyl peroxide (DCP) and benzoyl peroxide (BP) as curing agents. The vulcanization characteristics such as cure kinetics, activation energy, and cure rate of the blends were analyzed. The effects of blend ratio and curing agents on the mechanical properties such as stress–strain behavior, tensile strength, elongation at break, tear strength, relative volume loss, hardness, flex crack resistance, and density of the cured blends have been investigated. Almost all the mechanical properties have been found to be increased with increase in EVA content in the blends particularly in DCP‐cured systems. The increment in mechanical properties of the blends with higher EVA content has been explained in terms of the morphology of the blends, attested by scanning electron micrographs. Attempts have been made to compare the experimental results, from the evaluation of mechanical properties, with relevant theoretical models. The aging characteristics of the cured blends were also investigated and found that both the DCP‐ and BP‐cured blends have excellent water and thermal resistance. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1069–1082, 2006
Synthesis of a new chitosan immobilized with β‐cyclodextrins and its adsorption properties for bilirubin
Authors: Yi Ying , Wang Yuting , Zhang Weian
Published: November 2005

A new chitosan derivative of chitosan immobilized with β‐cyclodextrins (CTC) has been synthesized by the reaction of chitosan and allyl‐substituted β‐cyclodextrins (ASC). Its structure has been proved by Fourier transform infrared spectral analysis, X‐ray powder diffraction analysis, and chemical analysis. Its adsorption of bilirubin has been also studied. By the experiment, it has been found that this new product has good adsorption ability on bilirubin. At initial 2 h, the adsorption increased largely. The adsorption mechanism was also dealt with. It predicted that this new chitosan derivative could have application in removing the bilirubin. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1264–1268, 2006
Blends of thermotropic liquid crystalline polymer and O‐cresol formaldehyde epoxy resin. II. Curing kinetics
Authors: Tan Song Ting , Huang Zeng Fang , Liu Min Na , Wang Xia Yu
Published: November 2005

Curing kinetics of O‐cresol formaldehyde epoxy resin and its blends with a liquid crystalline block copolymer (PDBH) cured with linear phenol–formaldehyde resin were studied by the nonisothermal differential scanning calorimetry (DSC) and isothermal DSC methods. The parameters of nonisothemal curing kinetics were obtained according to the Kissinger method, and those of isothermal curing kinetics were deduced on the basis of the n‐order mechanism proposed by Kamal. The curing reaction is considered 1‐order reaction as shown by the nonisothermal and isothermal results. The model gave a good description of curing kinetics up to the onset of vitrification. A diffusion factor has been introduced in the latter stage of reaction to describe the degree of conversion over the whole range. The obtained n‐order model modified by diffusion‐controlled factor is consistent with the experimental data almost over the whole range of conversion. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1269–1276, 2006
In‐situ curing analysis of photoreplicated objective lenses using Raman and IR spectroscopy
Authors: Mank Arjan , Verstegen Emile , Kloosterboer Hans
Published: November 2005

Optical pick‐up lenses are used in optical storage devices such as CD, DVD, and Blu‐Ray Disc. The production of such lenses is based on UV‐induced polymerization of a mixture of a dimethacrylate monomer and an initiator on a spherical glass substrate. The shape of the polymer layer is defined with an aspherical transparent mold. This means that the coating is completely surrounded by glassy materials during processing. Raman spectroscopy is applied in situ to monitor the polymerization reaction under conditions that closely resemble the actual production process. As a result improvements can be made to the reaction conditions if necessary. Data are compared to results obtained with IR spectroscopy in an off‐line approach. The value of the in situ characterization using Raman spectroscopy is illustrated by the observation that contrary to expectation, the local rate of polymerization is not influenced by shrinkage effects caused by local variations in volume relaxation in the wedge‐shaped sample volume. Instead, even quartz glass mold plates with a thickness of 30 times that of liquid monomer were deformed to accommodate for thermodynamically required volume shrinkage. The assumption of isochoric polymerization in a confined volume turned out to be incorrect. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1287–1295, 2006
Parasitic suppression of feeding in the tobacco hornworm,Manduca sexta: Parallels with feeding depression after an immune challenge
Authors: Adamo Shelley A.
Published: November 2005

The parasitic wasp,Cotesia congregata, suppresses feeding in its hostManduca sexta. Feeding suppression in the host coincides with the emergence of the wasps through the host's cuticle. During wasp emergence, host hemocyte number declined, suggesting that the host mounts a wound/immune response against the exiting parasitoids and/or resulting tissue damage. Eliciting a different type of immune response by injecting heat‐killedSerratia marcescensalso resulted in a decline in feeding and a reduction in hemocyte number. Both the emerging wasps and the bacteria induced an increase in hemolymph octopamine concentration and a decrease in foregut peristalsis inM. sexta. The emerging parasitoids produced the largest changes. The source of the additional octopamine appeared to be the host in both cases.S. marcescenswas found to contain no detectable amounts of octopamine. The parasitoids had insufficient octopamine to account for the amount found in host hemolymph and they did not secrete octopamine in vitro. One cause for the high concentration of octopamine in parasitizedM. sextawas that octopamine was removed from the hemolymph approximately 23 times more slowly after the wasps emerged than prior to wasp emergence. The striking similarity between the effects of parasitoids and bacteria onM. sextafeeding, hemocyte number, hemolymph octopamine concentration, and foregut peristalsis supports the possibility that the immune/wound reaction induced by the emerging wasps could play a role in the suppression of host feeding. These results also support the hypothesis thatM. sextaexhibit an immune‐activated anorexia. Arch. Insect Biochem. Physiol. 60:185–197, 2005. © 2005 Wiley‐Liss, Inc.
Long‐range coordination of planar polarity in Drosophila
Authors: Strutt Helen , Strutt David
Published: November 2005

The mechanisms by which cells become polarised in the plane of an epithelium have been studied in Drosophila for many years. Work has focussed on two key questions: firstly, how individual cells adopt a defined polarity, and secondly how the polarity of each cell within a tissue is aligned with its neighbours. It has been established that asymmetric subcellular localisation of a number of polarity proteins is an essential mechanism underlying polarisation of single cells. The process by which this polarity is coordinated between cells however is less well understood, but is thought to involve gradients of activity of the atypical cadherins Dachsous and Fat. Subsequently, this long‐range polarity signal is refined by local cell–cell interactions involving the transmembrane molecules Frizzled, Strabismus and Flamingo. The role of these factors in coordinating polarity will be discussed. BioEssays 27:1218–1227, 2005. © 2005 Wiley Periodicals, Inc.
My favorite animal, Trichoplax adhaerens
Authors: Schierwater Bernd
Published: November 2005

Trichoplax adhaerens is more simply organized than any other living metazoan. This tiny marine animal looks like a irregular “hairy plate” (“tricho plax”) with a simple upper and lower epithelium and some loose cells in between. After its original description by F.E. Schulze 1883, it attracted particular attention as a potential candidate representing the basic and ancestral state of metazoan organization. The lack of any kind of symmetry, organs, nerve cells, muscle cells, basal lamina and extracellular matrix originally left little doubt about the basal position of T. adhaerens. Nevertheless, the interest of zoologists and evolutionary biologists suddenly vanished for more than half a century when Trichoplax was claimed to be an aberrant hydrozoan planula larva. Recently, Trichoplax has been rediscovered as a key species for unraveling early metazoan evolution. For example, research on regulatory genes and whole genome sequencing promise insights into the genetics underlying the origin and development of basal metazoan phyla. Trichoplax offers unique potential for understanding the minimal requirements of metazoan animal organization. BioEssays 27:1294–1302, 2005. © 2005 Wiley Periodicals, Inc.
The Y chromosome as a target for acquired and amplified genetic material in evolution
Authors: Gvozdev Vladimir A. , Kogan Galina L. , Usakin Lev A.
Published: November 2005

The special properties of the Y chromosome stem form the fact that it is a non‐recombining degenerate derivative of the X chromosome. The absence of homologous recombination between the X and the Y chromosome leads to gradual degeneration of various Y chromosome genes on an evolutionary timescale. The absence of recombination, however, also favors the accumulation of transposable elements on the Y chromosome during its evolution, as seen with both Drosophila and mammalian Y chromosomes. Alongside these processes, the acquisition and amplification of autosomal male benefit genes occur. This review will focus on recent studies that reveal the autosome‐acquired genes on the Y chromosome of both Drosophila and humans. The evolution of the acquired and amplified genes on the Y chromosome is also discussed. Molecular and comparative analyses of Y‐linked repeats in the Drosophila melanogaster genome demonstrate that there was a period of their degeneration followed by a period of their integration into RNAi silencing, which was beneficial for male fertility. Finally, the function of non‐coding RNA produced by amplified Y chromosome genetic elements will be discussed. BioEssays 27:1256–1262, 2005. © 2005 Wiley Periodicals, Inc.
Different species problems and their resolution
Authors: de Queiroz Kevin
Published: November 2005

At least three different issues are commonly referred to by the term “the species problem”: one concerns the necessary properties of species, a second the processes responsible for the existence of species, and a third methods for inferring species limits. Solutions have recently been proposed to the first two problems, which are conceptual in nature (the third is methodological). The first equates species with metapopulation lineages and proposes that existence as a separately evolving metapopulation lineage be considered the only necessary property of species. The second views the species category as a cluster concept and proposes that no single process or set of processes be considered necessary for the existence of species. Although these two solutions have been portrayed as being in conflict, they are, in fact, highly compatible. Moreover, the proposals in question clarify the problem concerning methods for inferring the limits of species, which has for a long time been confused with the problem concerning the necessary properties of species. Together these proposals provide the opportunity for biology to move beyond debates about the definition of the species category and focus on estimating the boundaries and numbers of species as well as studying the diverse processes involved in their origin and persistence. BioEssays 27:1263–1269, 2005. © 2005 Wiley Periodicals, Inc.
Stochastic gene expression, disruption of tissue averaging effects and cancer as a disease of development
Authors: Capp Jean‐Pascal
Published: November 2005

Despite the extensive literature describing the somatic genetic alterations in cancer cells, the precise origins of cancer cells remain controversial. In this article, I suggest that the etiology of cancer and the generation of genetic instability in cancer cells should be considered in the light of recent findings on both the stochastic nature of gene expression and its regulation at tissue level. By postulating that gene expression is intrinsically probabilistic and that stabilization of gene expression arises by cellular interactions in “morphogenetic fields”, development and cellular differentiation can be rethought in an evolutionary perspective. In particular, this article proposes that disruptions of cellular interactions are the initial source of abnormal gene expression in cancer cells. Consequently, cancer phenotypes such as genetic and epigenetic instabilities, and also the presence of cells with stem cell‐like properties, may result from inaccurate and aberrant patterns of gene expression generated by microenvironmental alterations. Finally, the therapeutic implications of this view are discussed. BioEssays 27:1277–1285, 2005. © 2005 Wiley Periodicals, Inc.
TIRs of joy: new receptors for auxin
Authors: Napier Richard M.
Published: November 2005

Back‐to‐back papers have described the identification of a family of receptors for the plant hormone auxin.(1, 2) Most developmental processes in plants are dependent on auxin signalling making this discovery a landmark in the search for the mechanism of auxin action. The TIR1 gene translates into a protein with recognised motifs including an F‐box domain and TIR1 forms part of an important ubiquitination complex that tags other proteins for degradation.(3) Specific amongst the targets of TIR1 are a set of auxin‐regulated transcription factors.(4) The latest work has shown that TIR1 itself is also the binding site for auxin making it an auxin receptor with no requirement for a biochemical signalling cascade. BioEssays 27:1213–1217, 2005. © 2005 Wiley Periodicals, Inc.
Stabilization of Taq DNA Polymerase at High Temperature by Protein Folding Pathways From a Hyperthermophilic Archaeon, Pyrococcus furiosus
Authors: Laksanalamai Pongpan , Pavlov Andrey R. , Slesarev Alexei I. , Robb Frank T.
Published: November 2005

Pyrococcus furiosus, a hyperthermophilic archaeon growing optimally at 100°C, encodes three protein chaperones, a small heat shock protein (sHsp), a prefoldin (Pfd), and a chaperonin (Cpn). In this study, we report that the passive chaperones sHsp and Pfd from P. furiosus can boost the protein refolding activity of the ATP‐dependent Cpn from the same hyperthermophile. The thermo‐stability of Taq polymerase was significantly improved by combinations of P. furiosus chaperones, showing ongoing protein folding activity at elevated temperatures and during thermal cycling. Based on these results, we propose that the protein folding apparatus in the hyperthermophilic archaeon, P. furiosus can be utilized to enhance the durability and cost effectiveness of high temperature biocatalysts. © 2005 Wiley Periodicals, Inc.
Facile Synthesis and Optimization of Conductive Copolymer Nanoparticles and Nanocomposite Films from Aniline with Sulfodiphenylamine
Authors: Li Xin‐Gui , Lü Qiu‐Feng , Huang Mei‐Rong
Published: November 2005

A new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine‐4‐sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV‐visible spectroscopy, X‐ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above‐mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought‐after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90×10−4 to 1.15×10−2 S cm−1 with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98 % of the transparency, 94 % of the strength, and 5×107 times the conductivity of a pure cellulose diacetate film.
New Insights into the Mechanism of Proton Transfer to Hydride Complexes: Kinetic and Theoretical Evidence Showing the Existence of Competitive Pathways for Protonation of the Cluster [W3S4H3(dmpe)3]+ with Acids
Authors: Algarra Andrés G. , Basallote Manuel G. , Feliz Marta , Fernández‐Trujillo M. Jesús , Llusar Rosa , Safont Vicent S.
Published: November 2005

The reaction of the hydride cluster [W3S4H3(dmpe)3]+ (1, dmpe=1,2‐bis(dimethylphosphanyl)ethane) with acids (HCl, CF3COOH, HBF4) in CH2Cl2 solution under pseudo‐first‐order conditions of excess acid occurs with three kinetically distinguishable steps that can be interpreted as corresponding to successive formal substitution processes of the coordinated hydrides by the anion of the acid (HCl, CF3COOH) or the solvent (HBF4). Whereas the rate law for the third step changes with the nature of the acid, the first two kinetic steps always show a second‐order dependence on acid concentration. In contrast, a single kinetic step with a first‐order dependence with respect to the acid is observed when the experiments are carried out with a deficit of acid. The decrease in the T1 values for the hydride NMR signal of 1 in the presence of added HCl suggests the formation of an adduct with a WH⋅⋅⋅HCl dihydrogen bond. Theoretical calculations for the reaction with HCl indicate that the kinetic results in CH2Cl2 solution can be interpreted on the basis of a mechanism with two competitive pathways. One of the pathways consists of direct proton transfer within the WH⋅⋅⋅HCl adduct to form WCl and H2, whereas the other requires the presence of a second HCl molecule to form a WH⋅⋅⋅HCl⋅⋅⋅HCl adduct that transforms into WCl, H2 and HCl in the rate‐determining step. The activation barriers and the structures of the transition states for both pathways were also calculated, and the results indicate that both pathways can be competitive and that the transition states can be described in both cases as a dihydrogen complex hydrogen‐bonded to Cl− or HCl2−.
Binding of Cationic and Neutral Phenanthridine Intercalators to a DNA Oligomer Is Controlled by Dispersion Energy: Quantum Chemical Calculations and Molecular Mechanics Simulations
Authors: Kubař Tomáš , Hanus Michal , Ryjáček Filip , Hobza Pavel
Published: November 2005

Correlated ab initio as well as semiempirical quantum chemical calculations and molecular dynamics simulations were used to study the intercalation of cationic ethidium, cationic 5‐ethyl‐6‐phenylphenanthridinium and uncharged 3,8‐diamino‐6‐phenylphenanthridine to DNA. The stabilization energy of the cationic intercalators is considerably larger than that of the uncharged one. The dominant energy contribution with all intercalators is represented by dispersion energy. In the case of the cationic intercalators, the electrostatic and charge‐transfer terms are also important. The ΔG of ethidium intercalation to DNA was estimated at −4.5 kcal mol−1 and this value agrees well with the experimental result. Of six contributions to the final free energy, the interaction energy value is crucial. The intercalation process is governed by the non‐covalent stacking (including charge‐transfer) interaction while the hydrogen bonding between the ethidium amino groups and the DNA backbone is less important. This is confirmed by the evaluation of the interaction energy as well as by the calculation of the free energy change. The intercalation affects the macroscopic properties of DNA in terms of its flexibility. This explains the easier entry of another intercalator molecule in the vicinity of an existing intercalation site.
Density Functional Studies of Dicobalt Octacarbonyl‐Mediated Azobenzene Formation from 4‐Ethynylaniline
Authors: Huang Yi‐Luen , Hong Fung‐E
Published: November 2005

Two adiabatic potential‐energy surfaces are employed for probing the processes of [Co2(CO)8]‐mediated C6H5NNC6H5 formation from NH2C6H5. Elementary steps, including oxidative addition of the coordinated amine proton to the cobalt center, reductive elimination of H2, CO association, and the coupling process of the diamino fragments, are modeled and examined by using DFT methods at the B3 LYP/631 LAN level. The formation of C6H5NNC6H5 from NH2C6H5 through reductive coupling is a thermodynamically unfavorable process. Three hydride‐migration processes, from the proton of NH to the cobalt center, are established as the most energy‐demanding steps. The activation energies (ΔG*) are calculated as 49.4, 55.4, and 33.3 kcal mol−1, respectively, for the proposed reaction route 1. These large activation energies might be reduced slightly by purposely adding small protic molecules, such as H2O, or by changing the active metal from Co to a heavier metal, such as Rh or Ir. An alternative pathway, route 2, is also proposed, in which transition states with four‐membered rings are formed. By this route, severe strain caused by the formation of three‐membered rings during the hydride‐migration processes in route 1 can be avoided. Route 2 is established as the more energy‐feasible reaction pathway.
Solid‐Phase Synthesis and Biological Activity of a Combinatorial Cross‐Conjugated Dienone Library
Authors: Kitade Makoto , Tanaka Hiroshi , Oe Sho , Iwashima Makoto , Iguchi Kazuo , Takahashi Takashi
Published: November 2005

The solid‐phase synthesis of a combinatorial cross‐conjugated dienone library based on the structure of clavulones and their biological activity are reported. Clavulones are a family of marine prostanoids, and are composed of a cross‐conjugated dienone system bearing two alkyl side‐chains. The cross‐conjugated dienone system irreversibly reacted with two nucleophiles. Our strategy for the solid‐phase synthesis of the cross‐conjugated dienones involves the Sonogashira‐coupling reaction of a solid‐supported cyclopentenone 10 bearing an acetylene group, followed by aldol condensation with aldehydes. The diphenyl derivative 7 aA was prepared from the solid‐supported cyclopentenone 10 in 56 % total yield. Combinatorial synthesis of a small library using twelve halides and eight aldehydes resulted in the production of 74 desired compounds from 98 candidates, and were detected by their mass spectra. Antiproliferative effects of the crude compounds against HeLaS3 cells showed that eleven samples showed strong antitumor activity (IC50<0.05 μM). Further biological examination of four purified compounds by using five tumor cell lines (A549, HeLaS3, MCF7, TMF1, and P388) revealed strong cytotoxicity comparable to that of adriamycin.
Unprecedented Stereoselective Synthesis of Catalytically Active Chiral Mo3CuS4 Clusters
Authors: Feliz Marta , Guillamón Eva , Llusar Rosa , Vicent Cristian , Stiriba Salah‐Eddine , Pérez‐Prieto Julia , Barberis Mario
Published: November 2005

Cluster excision of polymeric {Mo3S7Cl4}n phases with chiral phosphane (+)‐1,2‐bis[(2R,5R)‐2,5‐(dimethylphospholan‐1‐yl)]ethane ((R,R)‐Me‐BPE) or with its enantiomer ((S,S)‐Me‐BPE) yields the stereoselective formation of the trinuclear cluster complexes [Mo3S4{(R,R)‐Me‐BPE}3Cl3]+ ([(P)‐1]+) and [Mo3S4{(S,S)‐Me‐BPE}3Cl3]+ ([(M)‐1]+), respectively. These complexes posses an incomplete cuboidal structure with the metal atoms defining an equilateral triangle and one capping and three bridging sulfur atoms. The P and M symbols refer to the rotation of the chlorine atoms around the C3 axis, with the capping sulphur atom pointing towards the viewer. Incorporation of copper into these trinuclear complexes affords heterodimetallic cubane‐type compounds of formula [Mo3CuS4{(R,R)‐Me‐BPE}3Cl4]+ ([(P)‐2]+) or [Mo3CuS4{(S,S)‐Me‐BPE}3Cl4]+ ([(M)‐2]+), respectively, for which the chirality of the trinuclear precursor is preserved in the final product. Cationic complexes [(P)‐1]+, [(M)‐1]+, [(P)‐2]+, and [(M)‐2]+ combine the chirality of the metal cluster framework with that of the optically active diphosphane ligands. The known racemic [Mo3CuS4(dmpe)3Cl4]+ cluster (dmpe=1,2‐bis(dimethylphosphanyl)ethane) as well as the new enantiomerically pure Mo3CuS4 [(P)‐2]+ and [(M)‐2]+ complexes are efficient catalysts for the intramolecular cyclopropanation of 1‐diazo‐5‐hexen‐2‐one (3) and for the intermolecular cyclopropanation of alkenes, such as styrene and 2‐phenylpropene, with ethyl diazoacetate. In all cases, the cyclopropanation products were obtained in high yields. The diastereoselectivity in the intermolecular cyclopropanation of the alkenes and the enantioselectivity in the inter‐ or intramolecular processes are only moderate.
A Photocontrolled β‐Hairpin Peptide
Authors: Dong Shou‐Liang , Löweneck Markus , Schrader Tobias E. , Schreier Wolfgang J. , Zinth Wolfgang , Moroder Luis , Renner Christian
Published: November 2005

β‐Hairpins constitute the smallest β‐type structures in peptides and proteins. The development of highly stable, yet monomeric β‐hairpins based on the tryptophan zipper motif was therefore a remarkable success [A. G. Cochran, N. J. Skelton, M. A. Starovasnik, Proc. Natl. Acad. Sci USA 2001, 98, 5578–5583]. We have been able to design, synthesize and characterize a hairpin based on this motif which incorporates an azobenzene‐based photoswitch, that allows for time‐resolved folding studies of β‐structures with unprecedented time resolution. At room temperature the trans‐azo isomer exhibits a mostly disordered structure; however, light‐induced isomerization to the cis‐azo form leads to a predominantly extended and parallel conformation of the two peptide parts, which are linked by the novel photoswitch, [3‐(3‐aminomethyl)phenylazo]phenylacetic acid (AMPP). While in the original sequence the dipeptide Asn‐Gly forms a type I′ β‐turn which connects the two strands of the hairpin, this role is adopted by the AMPP chromophore in our photoresponsive β‐hairpin that can apparently act as a β I′‐turn mimetic. The β‐hairpin structure was determined and confirmed by NMR spectroscopy, but the folding process can be monitored by pronounced changes in the CD, IR and fluorescence spectra. Finally, incorporation of the structurally and functionally important β‐hairpin motif into proteins by chemical ligation might allow for the photocontrol of protein structures and/or functions.
Alkylboron and ‐silicon Compounds
Authors: Fraser W.
Published: November 2005

For Abstract see ChemInform Abstract in Full Text.
Pilot intervention to enhance sexual rehabilitation for couples after treatment for localized prostate carcinoma
Authors: Canada Andrea L. , Neese Leah E. , Sui Dawen , Schover Leslie R.
Published: November 2005

BACKGROUND

The majority of prostate carcinoma survivors experience enduring sexual difficulties and associated distress in the years after definitive treatment. A counseling intervention aimed at improving levels of sexual satisfaction and increasing successful utilization of medical treatment for erectile dysfunction (ED) was developed and pilot‐tested for both the survivor of prostate carcinoma and his partner.

METHODS

All male participants were 3‐month to 5‐year survivors of localized prostate carcinoma who had been treated with radical prostatectomy or radiation therapy, and were married or in a committed relationship. Couples were randomized to attend four sessions of counseling together or to have the man attend alone. In both groups, partners completed behavioral homework. The sessions included education on prostate carcinoma and sexual function and options to treat ED as well as sexual communication and stimulation skills. Standardized questionnaires at baseline, posttreatment, and at 3‐month and 6‐month follow‐up assessed sexual function, marital adjustment, psychologic distress, and utilization of treatments for ED.

RESULTS

Fifty‐one of 84 couples randomized to treatment completed the intervention (61%). Attendance by the partner did not affect outcomes. Participants completing the intervention demonstrated improvment in male overall distress (P < 0.01), male global sexual function (P < 0.0001), and female global sexual function (P < 0.05) at 3‐month follow‐up, but regression toward baseline was noted at 6‐month follow‐up. However, utilization of ED treatments increased from 31% at the time of study entry to 49% at the 6‐month follow‐up (P = 0.003).

CONCLUSIONS

The results of this brief pilot counseling intervention demonstrated significant gains in sexual function and satisfaction and increased utilization of treatments for ED. However, modifications are needed in future randomized trials to reduce the rate of premature termination and to improve long‐term maintenance of gains. Cancer 2005. © 2005 American Cancer Society.
Distinct expression of TRPM8, TRPA1, and TRPV1 mRNAs in rat primary afferent neurons with aδ/c‐fibers and colocalization with trk receptors
Authors: Kobayashi Kimiko , Fukuoka Tetsuo , Obata Koichi , Yamanaka Hiroki , Dai Yi , Tokunaga Atsushi , Noguchi Koichi
Published: November 2005

The transient receptor potential (TRP) superfamily of cation channels contains four temperature‐sensitive channels, named TRPV1–4, that are activated by heat stimuli from warm to that in the noxious range. Recently, two other members of this superfamily, TRPA1 and TRPM8, have been cloned and characterized as possible candidates for cold transducers in primary afferent neurons. Using in situ hybridization histochemistry and immunohistochemistry, we characterized the precise distribution of TRPA1, TRPM8, and TRPV1 mRNAs in the rat dorsal root ganglion (DRG) and trigeminal ganglion (TG) neurons. In the DRG, TRPM8 mRNA was not expressed in the TRPV1‐expressing neuronal population, whereas TRPA1 mRNA was only seen in some neurons in this population. Both A‐fiber and C‐fiber neurons expressed TRPM8, whereas TRPV1 was almost exclusively seen in C‐fiber neurons. All TRPM8‐expressing neurons also expressed TrkA, whereas the expression of TRPV1 and TRPA1 was independent of TrkA expression. None of these three TRP channels were coexpressed with TrkB or TrkC. The TRPM8‐expressing neurons were more abundant in the TG compared with the DRG, especially in the mandibular nerve region innervating the tongue. Our data suggest heterogeneity of TRPM8 and TRPA1 expression by subpopulations of primary afferent neurons, which may result in the difference of cold‐sensitive primary afferent neurons in sensitivity to chemicals such as menthol and capsaicin and nerve growth factor. J. Comp. Neurol. 493:596–606, 2005. © 2005 Wiley‐Liss, Inc.