bluuebunny/crossref_metadata_2025 huggingface dataset:
Friction and wear behavior of basalt‐fabric‐reinforced/solid‐lubricant‐filled phenolic composites
Authors: Zhang Xinrui , Pei Xianqiang , Wang Qihua
Published: May 2010

To improve the tribological properties of basalt‐fabric‐reinforced phenolic composites, solid lubricants of MoS2 and graphite were incorporated, and the tribological properties of the resulting basalt‐fabric composites were investigated on a model ring‐on‐block test rig under dry sliding conditions. The effects of the filler content, load, and sliding time on the tribological behavior of the basalt‐fabric composites were systematically examined. The morphologies of the worn surfaces and transfer films formed on the counterpart steel rings were analyzed by means of scanning electron microscopy. The experimental results reveal that the incorporation of MoS2 significantly decreased the friction coefficient, whereas the inclusion of graphite improved the wear resistance remarkably. The results also indicate that the filled basalt‐fabric composites seemed to be more suitable for friction materials serving under higher loads. The transfer films formed on the counterpart surfaces during the friction process made contributions to the reduction of the friction coefficient and wear rate of the basalt‐fabric composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and conductivity performance of hyperbranched polymer electrolytes with terminal ionic groups
Authors: Chen Chunming , Fang Xiaoling
Published: May 2010

Hyperbranched polymer was synthesized from pentaerythritol (as the central core), 1,2,4‐trimellitic anhydride, and epichlorohydrin, and then hyperbranched polymer electrolytes with terminal ionic groups were prepared by the reaction of hyperbranched polymer with N‐methyl imidazole. The chemical structure, thermal behavior, and ionic conductive property of the hyperbranched polymer electrolytes were investigated by 1H‐NMR, FTIR, differential scanning calorimetry, thermogravimetric analyzer, and complex impedance analysis, respectively. The ionic conductivity of hyperbranched polymer electrolyte was up to 2.4 × 10−4 S cm−1 at 30°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of surface modification on ionic permeability across cellophane membrane
Authors: Banihashemi Ahmad , Vakili Mohammad Reza , Meratian Shahrzad
Published: May 2010

Cellophane membrane is used for different kinds of membranes and separators because of its advantages. Regenerated cellulose is a hydrophilic membrane; however, it cannot dissolve in water. The operation time of cellophane membrane is short because of the hydrolytic cleavage during the operation. In this study, cellophane membrane was treated by epichlorohydrin. As a result, the surface of the cellophane membrane was changed chemically and morphologically. These changes were investigated by means of FT‐IR, scanning electron microscopy, and also the surface properties were studied by contact angle and water absorption. In addition to, hydrolysis behavior, oxidative resistance, and salt permeability were measured. Meanwhile, thermal stability and tensile strength were done on modified and unmodified membrane. The modified membrane is more resistant against the hydrolytic and oxidative cleavage than the unmodified membrane. Salt permeabilitys were increased after treatment. Modification causes to increase thermal stability and tensile strength of the untreated cellophane membrane. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Study of plasma‐polyethylene interactions using electron beam‐generated plasmas produced in Ar/SF6 mixtures
Authors: Walton S. G. , Lock E. H. , Ni A. , Baraket M. , Fernsler R. F. , Pappas D. D. , Strawhecker K. E. , Bujanda A. A.
Published: May 2010

The use of electron beam‐generated plasmas produced in Ar/SF6 mixtures to modify the surface of ultra‐high molecular weight polyethylene substrates is discussed. Changes in the surface energy, chemistry, and morphology are presented as a function of plasma operating parameters, along with simple system diagnostics to obtain a better understanding of the plasma‐polymer interaction. For all conditions, the hydrophobicity of the material was increased via the incorporation of fluorine, and for some conditions, the surface was found to remain stable over the course of 1 year. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Physical properties and morphology of films prepared from microfibrillated cellulose and microfibrillated cellulose in combination with amylopectin
Authors: Plackett David , Anturi Harvey , Hedenqvist Mikael , Ankerfors Mikael , Gällstedt Mikael , Lindström Tom , Siró István
Published: May 2010

Two types of microfibrillated cellulose (MFC) were prepared using either a sulfite pulp containing a high amount of hemicellulose (MFC 1) or a carboxymethylated dissolving pulp (MFC 2). MFC gels were then combined with amylopectin solutions to produce solvent‐cast MFC‐reinforced amylopectin films. Tensile testing revealed that MFC 2‐reinforced films exhibited a more ductile behavior and that MFC 1‐reinforced films had higher modulus of elasticity (E‐modulus) at MFC loadings of 50 wt % or higher. Pure MFC films had relatively low oxygen permeability values when data were compared with those for a variety of other polymer films. MFC 1 and MFC 2 films had similar opacity but differences in appearance which were attributed to the presence of some larger fibers and nanofiber agglomerates in MFC 2. Field emission scanning electron microscopy (FE‐SEM) and atomic force microscopy (AFM) were used to illustrate the morphology of MFC nanofibers in pure films and in an amylopectin matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of poly(vinyl alcohol)/water glass (SiO2) nano‐hybrids via sol‐gel process
Authors: Tenkayala Sobha Rani , Subha Marata Chinna Subbarao , Gorla Venkata Reddy , Kim Yong Ha , Kashayi Chowdoji Rao , Chalapati Venkata Prasad
Published: May 2010

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as catalyst supporting. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with water glass. The inorganic phase was also modified by incorporating a hexamethyldisiloxane as precursor. The hybrid aerogel powder was analyzed by scanning electron microscopy, TG‐DTA, Nitrogen adsorption–desorption, X‐ray diffraction and fourier transform infrared spectroscopy (FTIR) spectroscopy. The powder obtained had a higher porosity varying from 65 to 90% and the nanopore diameter ranged from 17 to 20 nm. The surface area and nanopore volume decreased as polymer content increased in the hybrids. The sharp decline in the weight observed at around 500°C accompanied an exothermic peak of the DTA curve. The sharp peak was observed around 211°C represents the DTA curve of Poly vinyl alcohol constituent in nano hybrids. The peak at 1638 cm−1 in the FTIR indicated the formation of SiOPVAOSi bridge in aerogel powder. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A simple and efficient way to synthesize optically active polyamides by solution polycondensation of di‐O‐methyl‐L‐tartaryl chloride with diamines
Authors: Wu Zuolin , Huang Yanjiong , Zhang Chunhua , Zhu Danyang , Bian Zheng , Ding Mengxian , Gao Lianxun , Yang Zhenghua
Published: May 2010

A series of optically active polyamides containing di‐O‐methyl‐L‐tartaryl moieties in the main chain were synthesized by polycondensation of di‐O‐methyl‐L‐tartaryl chloride 5 with diamines and characterized by gel permeation chromatography, UV–vis, circular dichroism (CD), IR, and NMR spectroscopies. The polycondensation reaction could be carried out under mild conditions and the reaction time was short (2–3 h). The key monomer 5 prepared from L‐tartaric acid via esterification, etherification, hydrolysis, and chlorination was easily purified by vacuum sublimation. These polyamides with number average molecular weights ranging from 14,000 to 35,000, displayed large optical activity in dimethyl sulfoxide solution, and their specific optical rotations oscillated between 87.2° and 210.7° depending on the structures of the diamines. The glass transition temperatures of these polyamides were in the range of 106–191°C, and the 10% mass loss occurred at temperature above 300°C. The polyamides derived from aromatic diamines exhibited higher Tg and thermal stability than those derived from aliphatic diamines. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of PEG–PCL–PEG triblock copolymers as carriers of doxorubicin for the treatment of breast cancer
Authors: Cuong Nguyen‐Van , Hsieh Ming‐Fa , Chen Yung‐Tsung , Liau Ian
Published: May 2010

Triblock copolymers of monomethoxy poly(ethylene glycol) (mPEG) and ε‐caprolactone (CL) were prepared with varying lengths of poly(ε‐caprolactone) (PCL) compositions and a fixed length of mPEG segment. The molecular characteristics of triblock copolymers were characterized by 1H NMR, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and differential scanning calorimetry (DSC). These amphiphilic linear copolymers based on PCL hydrophobic chain and hydrophilic mPEG ending, which can self‐assemble into nanoscopic micelles with their hydrophobic cores, encapsulated doxorubicin (DOX) in an aqueous solution. The particle size of prepared micelles was around 40–92 nm. The DOX loading content and DOX loading efficiency were from 3.7–7.4% to 26–49%, respectively. DOX‐released profile was pH‐dependent and faster at pH 5.4 than pH 7.4. Additionally, the cytotoxicity of DOX‐loaded micelles was found to be similar with free DOX in drug‐resistant cells (MCF‐7/adr). The great amounts of DOX and fast uptake accumulated into the MCF‐7/adr cells from DOX‐loaded micelles suggest a potential application in cancer chemotherapy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Reduction of dissolved oxygen in boiler water using new redox polymers
Authors: Waterlot Christophe , Couturier Daniel
Published: May 2010

New polymers were used as catalysts for the removal of dissolved oxygen in boiler water. These polymers, based upon hydroquinone‐quinone redox system, were prepared by polymerization of methyl 4‐(2,5‐dimethoxybenzyl)cinnamate and copolymerization of this monomer with 4‐(4′‐vinylphenethyl)‐1,10‐phenanthroline. The resulting product was used to synthesize polymers containing transition metal ions. Nuclear magnetic resonance, infrared spectroscopy, and elemental analysis were achieved to characterize monomers and/or electron‐transfer polymers. These polymers were used for the removal of oxygen from water. It was shown that the oxygen content was reduced to less than 0.1 mg L−1 in ∼ 70 s. Based on the obtained results, the redox capacity of two polymers were determined. It was established that the poly‐4‐(2,5‐dihydroxybenzyl)cinnamic acid reached a redox capacity of 69.7 mg of O2 per gram of polymer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of agarose‐graft‐hyaluronan copolymer and its potential application as a peptide carrier
Authors: Huang Jian‐Yan , Bao Lei , Mao Xuan , Tang Shun‐Qing
Published: May 2010

A novel water‐soluble copolymer, agarose‐graft‐hyaluronan (Ag‐g‐HA), was synthesized as a peptide carrier, and selected properties were evaluated. In brief, agarose was degraded by hydrogen peroxide to achieve agarose with a low gelling temperature and a low molecular weight, activated by epichlorohydrin, and grafted with hyaluronic acid. The IR spectrum results of the Ag‐g‐HA copolymer showed that there were specific absorption peaks of hyaluronan at 1609 cm−1 (CO), which proved that hyaluronan was successfully grafted onto the agarose chain. The elemental analysis results showed that the nitrogen content of Ag‐g‐HA was 2.57%. The grafting ratio of epoxy groups was deduced to be 66.41% according to the N content of the copolymer. The ζ potential analysis results disclosed that Ag‐g‐HA became negative with increasing pH above 3. Ag‐g‐HA/insulin (INS) polyelectrolyte complexes were formed via electrostatic interaction at pH 3–5.4. The results of atomic force microscopy and ζ potential analyses demonstrated that Ag‐g‐HA and INS could spontaneously form microparticles with average diameters of 2–10 μm. The result of an INS‐releasing experiment in vitro disclosed that these particles had a significant burst release effect during the initial 30 min of release at pH 1.2 or 7.4, but the release behavior was ideal in the environment of pH 6.8. The release data could be described by the Weibull equation. These results demonstrate that the Ag‐g‐HA copolymer possessed potential as a peptide carrier. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nickel(II)‐imprinted monolithic columns for selective nickel recognition
Authors: Demiralay Ebru Çubuk , Andac Muge , Say Rıdvan , Alsancak Guleren , Denizli Adil
Published: May 2010

Ni2+‐imprinted monolithic column was prepared for the removal of nickel ions from aqueous solutions. N‐Methacryloyl‐L‐histidine was used as a complexing monomer for Ni2+ ions in the preparation of the Ni2+‐imprinted monolithic column. The Ni2+‐imprinted poly(hydroxyethyl methacrylate‐N‐methacryloyl‐L‐histidine) (PHEMAH) monolithic column was synthesized by bulk polymerization. The template ion (Ni2+) was removed with a 4‐(2‐pyridylazo) resorcinol (PAR):NH3NH4Cl solution. The water‐uptake ratio of the PHEMAH–Ni2+ monolith increased compared with PHEMAH because of the formation of nickel‐ion cavities in the polymer structure. The adsorption of Ni2+ ions on both the PHEMAH–Ni2+ and PHEMAH monoliths were studied. The maximum adsorption capacity was 0.211 mg/g for the PHEMAH–Ni2+ monolith. Fe3+, Cu2+, and Zn2+ ions were used as competitive species in the selectivity experiments. The PHEMAH–Ni2+ monolithic column was 268.8, 25.5, and 10.4 times more selective than the PHEMAH monolithic column for the Zn2+, Cu2+, and Fe3+ ions, respectively. The PHEMAH–Ni2+ monolithic column could be used repeatedly without a decrease in the Ni2+ adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Ultraviolet/heat dual‐curable film adhesives with pendant‐acryloyl‐functional‐group‐modified epoxy resin
Authors: Saiki Naoya , Kainou Sayaka , Shizuhata Hironori , Seno Hideo , Ebe Kazuyoshi
Published: May 2010

To facilitate the fabrication of a reliable semiconductor package, the UV/heat dual curing of film adhesives was investigated. The curing system of the epoxy resin affected the film adhesive properties. As the UV/heat dual‐curable epoxy resin, a modified o‐cresol novolak epoxy resin, in which half of the glycidyl groups were substituted by acryloyl groups (OCN‐AE), was applied to the film adhesive. The formulated film adhesive contained acrylic copolymer, OCN‐AE, phenolic aralkyl resin as a heat‐curing agent of the glycidyl groups, and 1‐hydroxycyclohexyl phenyl ketone as a photoinitiator of the acryloyl groups. The formulated reference film adhesive contained unmodified o‐cresol novolak epoxy resin (OCN‐E) in place of OCN‐AE. Formulated film adhesives containing a mixture of OCN‐E and o‐cresol novolak epoxy acrylate were also used as references. The morphology and the film adhesive properties were investigated. In these investigations, the film adhesive of OCN‐AE showed better adhesive properties, lower modulus, and a better stress‐relaxation ability than the referenced adhesives. As a result, a reliable film adhesive for semiconductor packages was successfully developed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of novel polyindene/polyoxymethylene blends and investigation of their properties
Authors: Cabuk Tenzile Zilhan , Sari Bekir , Unal Halil Ibrahim
Published: May 2010

In this study, the conducting homopolymer of indene was synthesized by a chemical polymerization method in a nonaqueous medium, and polyindene (PIn)/polyoxymethylene (POM) blends were prepared. The physical, chemical, thermal, and spectral properties of the synthesized homopolymer and their blends were investigated. The conductivities of PIn and the PIn/POM blends were measured with a four‐probe technique. The conductivity of PIn was determined as 1.16 × 10−5 S/cm, whereas the conductivities of the PIn/POM blends were determined to be in the range 3.16 × 10−6 to 9.8 × 10−6 S/cm. From Gouy scale magnetic susceptibility measurements, we found that PIn and the PIn/POM blends had polaron natures. The amount of Fe (milligrams per gram) in the PIn and PIn/POM structures were determined by inductively coupled plasma–optic emission spectrometry. Fourier transform infrared spectra were taken to analyze the structural properties of PIn and the PIn/POM blends. The thermal properties of PIn and PIn/POM blends were investigated with thermogravimetric analysis and differential scanning calorimetry analyses, and we found that they showed adequate thermal stability. According to the initial decomposition temperature among the blends, the blend including 16% PIn had the highest decomposition temperature with 244°C. The morphological structures of the PIn, POM, and blends were clarified with scanning electron microscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Composites of rigid polyurethane foam and cellulose fiber residue
Authors: Silva M. C. , Takahashi J. A. , Chaussy D. , Belgacem M. N. , Silva G. G.
Published: May 2010

Rigid polyurethane composite foams were prepared with cellulose fibers as a filler. The cellulose fibers were an industrial residue of blanched cellulose pulp production. The influence of the cellulose fiber concentration on the structural, thermal, mechanical, and morphological properties of the foams was investigated. We also studied the influence of the cellulose fibers on the foam's resistance to fungal attack by placing a suspension of known fungus in contact with the surface of the foam and following the morphological evolution as a function of time (for 60 days). The increase in the cellulose filler concentration in the foams, up to 16% w/w with respect to the polyol, changed their properties as follows: (1) the cell size decreased, (2) the thermooxidative stability and mechanical properties remained approximately constant, (3) the thermal conductivity decreased slightly, and (4) fungal growth was observed. Therefore, a cellulosic fibrous industrial residue was rationally valorized as a filler in classical rigid polyurethane foams; this yielded materials with mechanical resistance and a susceptibility to fungi in a wet environment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Antibacterial activity of novel insoluble bead‐shaped polymer‐supported multiquaternary ammonium salts
Authors: Murugan E. , Gopinath P. , Shanmugayya V. , Mathivanan N.
Published: May 2010

This study describes the effect of antibacterial activity of newly reported five different novel insoluble bead‐shaped polymer‐supported multiquaternary ammonium salts (PM quats) viz., bis‐quat, tris‐quat (2 Nos.), tetrakis‐quat, hexakis‐quat containing two, three, four, and six quaternary ammonium groups, respectively. The presence of number of quaternary ammonium groups in each salt was established already through Fourier‐transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and chloride ion analyzes. The antibacterial activities of these five different PM quats against three different bacteria viz.,Staphylococcus aureus, Klebsiella pneumoniae, andPseudomonas aeruginosawere investigated by serial dilution and spread plate method and compared the same with a monoquat containing single quaternary ammonium group. The extent of antibacterial activity has been measured in terms of colony forming units (CFU) at different time intervals. The observed results show that all the PM quats exhibited excellent‐antibacterial activity against each bacterium. On the basis of the CFU values, the antibacterial activity was found to increase from bis‐quat to hexakis‐quat, which reveals that the activity of PM quats increases with increase in the number of quaternary ammonium groups. The mechanism of interaction of quats with bacterial cytoplasmic membrane has been explained as an adsorption‐like phenomenon. The reusability of highly active hexakis‐quat againstStaphylococcus aureuswas studied and the activity was found to reduce after first cycle. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A facile approach for fabricating fluorescent cellulose
Authors: Yang Qiang , Pan Xuejun
Published: May 2010

Fluorescent cellulose nanocrystals (CNCs) were prepared through a two‐step approach. Reactive amino groups were first introduced onto the CNCs through a silanization reaction with 3‐aminopropyltrimethoxysilane. The fluorescent moieties were then attached onto the cellulose by covalent grafting between the amino groups and 1‐pyrenebutyric acid N‐hydroxy succinimide ester or fluorescein isothiocyanate. The synthesized fluorescent CNCs were investigated and characterized with attenuated total reflectance Fourier transform infrared spectroscopy, ultraviolet–visible absorbance and fluorescence spectroscopy, confocal microscopy, and dynamic light scattering. The same fluorescent functionalization strategy could also be applied to other cellulose materials, such as microcrystalline cellulose and bulky paper sheets. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of long‐term natural aging on the thermal, mechanical, and viscoelastic behavior of biomedical grade of ultra high molecular weight polyethylene
Authors: Fouad H.
Published: May 2010

In the total joint prostheses, Ultra High Molecular Weight Polyethylene (UHMWPE) may undergo an oxidative degradation in the long term. The overall properties of UHMWPE are expected to be altered due to the oxidative degradation. The goal of this study is to investigate the effects of natural aging up to 6 years in air on the thermal, mechanical, and viscoelastic properties of UHMWPE that was used in total joint replacement. The changes in UHMWPE properties due to aging are determined using Differential Scanning Calorimetry (DSC), uniaxial tensile tests, and Dynamic Mechanical Analysis (DMA). The DSC results show that the lamellar thickness and degree of crystallinity of UHMWPE specimens increase by 38% and 12% due to aging. A small shoulder region in the DSC thermograms is remarked for aged specimens, which is an indication of formation of new crystalline forms within their amorphous region. The tensile properties of aged and nonaged UHMWPE specimens show a significant decrease in the elastic modulus, yield, fracture stresses, and strain at break due to aging. The DM testing results indicate that the storage modulus and creep resistance of UHMWPE specimens decrease significantly due to aging. Also, it is remarked that the α relaxation peak for aged UHMWPE specimens occurs at lower temperature compared to nonaged ones. The significant reduction in the strength and creep resistance of UHMWPE specimens due to aging would affect the long‐term clinical performance of the total joint replacement and should be taken into consideration during artificial joint design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Photomagnetic Switching of Heterometallic Complexes [M(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O (M=Nd, La, Gd, Y) Analyzed by Single‐Crystal X‐ray Diffraction and Ab Initio Theory
Authors: Svendsen Helle , Overgaard Jacob , Chevallier Marie A. , Collet Eric , Chen Yu‐Sheng , Jensen Frank , Iversen Bo B.
Published: May 2010

Single‐crystal X‐ray diffraction measurements have been carried out on [Nd(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O (1; dmf=dimethylformamide), [Nd(dmf)4(H2O)3(μ‐CN)Co(CN)5]⋅H2O (2), [La(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O (3), [Gd(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O (4), and [Y(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O (5), at 15(2) K with and without UV illumination of the crystals. Significant changes in unit‐cell parameters were observed for all the iron‐containing complexes, whereas 2 showed no response to UV illumination. Photoexcited crystal structures have been determined for 1, 3, and 4 based on refinements of two‐conformer models, and excited‐state occupancies of 78.6(1), 84(6), and 86.6(7) % were reached, respectively. Significant bond‐length changes were observed for the Fe–ligand bonds (up to 0.19 Å), the cyano bonds (up to 0.09 Å), and the lanthanide–ligand bonds (up to 0.10 Å). Ab initio theoretical calculations were carried out for the experimental ground‐state geometry of 1 to understand the electronic structure changes upon UV illumination. The calculations suggest that UV illumination gives a charge transfer from the cyano groups on the iron atom to the lanthanide ion moiety, {Nd(dmf)4(H2O)3}, with a distance of approximately 6 Å from the iron atom. The charge transfer is accompanied by a reorganization of the spin state on the {Fe(CN)6} complex, and a change in geometry that produces a metastable charge‐transfer state with an increased number of unpaired electrons, thus accounting for the observed photomagnetic effect.
Development of a Functional cis‐Prolyl Bond Biomimetic and Mechanistic Implications for Nickel Superoxide Dismutase
Authors: Tietze Daniel , Tischler Marco , Voigt Stephan , Imhof Diana , Ohlenschläger Oliver , Görlach Matthias , Buntkowsky Gerd
Published: May 2010

During recent years several peptide‐based Ni superoxide dismutase (NiSOD) models have been developed. These NiSOD models show an important structural difference compared to the native NiSOD enzyme, which could cause a completely different mechanism of superoxide dismutation. In the native enzyme the peptide bond between Leu4 and Pro5 is cis‐configured, while the NiSOD models exhibit a trans‐configured peptide bond between these two residues. To shed light on how the configuration of this single peptide bond influences the activity of the NiSOD model peptides, a new cis‐prolyl bond surrogate was developed. As surrogate we chose a leucine/alanine‐based disubstituted 1,2,3‐triazole, which was incorporated into the NiSOD model peptide replacing residues Leu4 and Pro5. The yielded 1,5‐disubstituted triazole nickel peptide exhibited high SOD activity, which was approximately the same activity as its parent trans‐configured analogue. Hence, the conformation of the prolyl peptide bond apparently has of minor importance for the catalytic activity of the metallopeptides as postulated in literature. Furthermore, it is shown that the triazole metallopeptide is forming a stable cyanide adduct as a substrate analogue model complex.
Two‐Photon Chemistry in Ruthenium 2,2′‐Bipyridyl‐Functionalized Single‐Wall Carbon Nanotubes
Authors: Martín Roberto , Jiménez Liliana , Alvaro Mercedes , Scaiano Juan C. , Garcia Hermenegildo
Published: May 2010

Ruthenium polypyridyl complexes are widely used as light harvesters in dye‐sensitized solar cells. Since one of the potential applications of single‐wall carbon nanotubes (SWCNTs) and their derived materials is their use as active components in organic and hybrid solar cells, the study of the photochemistry of SWCNTs with tethered ruthenium polypyridyl complexes is important. A water‐soluble ruthenium tris(bipyridyl) complex linked through peptidic bonds to SWCNTs (Ru‐SWCNTs) was prepared by radical addition of thiol‐terminated SWCNT to a terminal CC double bond of a bipyridyl ligand of the ruthenium tris(bipyridyl) complex. The resulting macromolecular Ru‐SWCNT (≈500 nm, 15.6 % ruthenium complex content) was water‐soluble and was characterized by using TEM, thermogravimetric analysis, chemical analysis, and optical spectroscopy. The emission of Ru‐SWCNT is 1.6 times weaker than that of a mixture of [Ru(bpy)3]2+ and SWCNT of similar concentration. Time‐resolved absorption optical spectroscopy allows the detection of the [Ru(bpy)3]2+‐excited triplet and [Ru(bpy)3]+. The laser flash studies reveal that Ru‐SWCNT exhibits an unprecedented two‐photon process that is enabled by the semiconducting properties of the SWCNT. Thus, the effect of the excitation wavelength and laser power on the transient spectra indicate that upon excitation of two [Ru(bpy)3]2+ complexes of Ru‐SWCNT, a disproportionation process occurs leading to delayed formation of [Ru(bpy)3]+ and the performance of the SWCNT as a semiconductor. This two‐photon delayed [Ru(bpy)3]+ generation is not observed in the photolysis of [Ru(bpy)3]3+; SWCNT acts as an electron wire or electron relay in the disproportionation of two [Ru(bpy)3]2+ triplets in a process that illustrates that the SWCNT plays a key role in the process. We propose a mechanism for this two‐photon disproportionation compatible with i) the need for high laser flux, ii) the long lifetime of the [Ru(bpy)3]2+ triplets, iii) the semiconducting properties of the SWNT, and iv) the energy of the HOMO/LUMO levels involved.
Synthetic and Structural Studies of 1,8‐Chalcogen Naphthalene Derivatives
Authors: Knight Fergus R. , Fuller Amy L. , Bühl Michael , Slawin Alexandra M. Z. , Woollins J. Derek
Published: May 2010

Four novel 1,8‐disubstituted naphthalene derivatives 4–7 that contain chalcogen atoms occupying the peri positions have been prepared and fully characterised by using X‐ray crystallography, multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular distortion due to noncovalent substituent interactions was studied as a function of the bulk of the interacting chalcogen atoms and the size and nature of the alkyl group attached to them. X‐ray data for 4–7 was compared to the series of known 1,8‐bis(phenylchalcogeno)naphthalenes 1–3, which were themselves prepared from novel synthetic routes. A general increase in the E⋅⋅⋅E′ distance was observed for molecules containing bulkier atoms at the peri positions. The decreased S⋅⋅⋅S distance from phenyl‐1 and ethyl‐4 analogues is ascribed to a weaker chalcogen lone pair–lone pair repulsion acting in the ethyl analogue due to the presence of two equatorial S(naphthyl) ring conformations. Two novel peri‐substituted naphthalene sulfoxides of 1, Nap(OSPh)(SPh) 8 and Nap(OSPh)2 9, which contain different valence states of sulfur, were prepared and fully characterised by using X‐ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. Molecular structures were analysed by using naphthalene ring torsions, peri‐atom displacement, splay angle magnitude, S⋅⋅⋅S interactions, aromatic ring orientations and quasi‐linear OS⋅⋅⋅S arrangements. The axial S(naphthyl) rings in 8 and 9 are unfavourable for S⋅⋅⋅S contacts due to stronger chalcogen lone pair–lone pair repulsion. Although quasi‐linear OS⋅⋅⋅S alignments suggest attractive interaction is conceivable, analysis of the B3LYP wavefunctions affords no evidence for direct bonding interactions between the S atoms.
Syntheses and Characterization of (C2F5)3BCO and (C3F7)3BCO
Authors: Gerken Michael , Pawelke Gottfried , Bernhardt Eduard , Willner Helge
Published: May 2010

The new tris(perfluoroalkyl)borane carbonyls, (C2F5)3BCO and (C3F7)3BCO, were prepared by means of a novel synthetic route using commercially available precursors by reacting K[(C2F5)3BCOOH] and K[(C3F7)3BCOOH] with concentrated sulfuric acid in the last step. The carboxylic acids, K[(C2F5)3BCOOH] and K[(C3F7)3BCOOH], were prepared by oxidative cleavage of the CC triple bonds in Cs[(C2F5)3BCCPh] and Cs[(C3F7)3BCCPh] in a two‐step process to yield K[(C2F5)3BCOCOPh] and K[(C3F7)3BCOCOPh] as isolable intermediates. Crystal structures were obtained of K[(C2F5)3BCOCOPh], K[(C2F5)3BCOOH]⋅H2O, (C2F5)3BCO, K[(C3F7)3BCOOH] ⋅2 H2O, and (C3F7)3BCO. In the crystal structures of (C2F5)3BCO and (C3F7)3BCO the CO bond lengths are 1.109(2) and 1.103(5) Å, respectively, which are among the shortest observed to date. Tris(pentafluoroethyl)borane carbonyl and (C3F7)3BCO slowly decompose at room temperature to yield CO, difluoroperfluoroalkylboranes and perfluoroalkenes. The decomposition of (C2F5)3BCO was found to follow a first‐order rate law with Ea=107 kJ mol−1.
On the Dewar–Chatt–Duncanson Model for Catalytic Gold(I) Complexes
Authors: Salvi Nicola , Belpassi Leonardo , Tarantelli Francesco
Published: May 2010

We provide a rigorous model‐free definition and a detailed theoretical analysis of the electron‐charge displacements making up the donation and back‐donation components of the Dewar–Chatt–Duncanson model in some realistic catalytic intermediates of formula L–AuI–S in which L is an N‐heterocyclic carbene or Cl− and S is an η2‐coordinated substrate containing a CC multiple bond. We thus show, contrary to a widely held view, that the goldsubstrate bond is characterized by a large π back‐donation component that is comparable to, and often as large as, the σ donation. The back‐donation is found to be a highly tunable bond component and we analyze its relationship with the nature of the auxiliary ligand L and with structural (interdependent) factors such as metal–substrate bond lengths and carbon pyramidalization.
ChemInform Abstract: A Vanadium Tellurate, (NH4)2[VO2]2 [TeO4(OH)2], Containing Two Edge‐Shared Square‐Pyramidal VO5 Groups.
Authors: Yun Gyiae , Hwang Yunmi , Yun Hoseop , Do Junghwan , Jacobson Allan J.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Fluoride Ion Donor Properties of cis‐OsO2F4: Synthesis, Raman Spectroscopic Study, and X‐Ray Crystal Structure of [OsO2F3][Sb2F11].
Authors: Hughes Michael J. , Mercier Helene P. A. , Schrobilgen Gary J.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Dynamic Kinetic Asymmetric Transformation (DYKAT) by Combined Amine‐ and Transition‐Metal‐Catalyzed Enantioselective Cycloisomerization.
Authors: Zhao Gui‐Ling , Ullah Farman , Deiana Luca , Lin Shuangzheng , Zhang Qiong , Sun Junliang , Ibrahem Ismail , Dziedzic Pawel , Cordova Armando
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A New Type of Organocatalyst for Highly Stereoselective Michael Addition of Ketones to Nitroolefins on Water.
Authors: Syu Siang‐en , Kao Tzu‐Ting , Lin Wenwei
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Copper‐Catalyzed Bromoalkynylation of Arynes.
Authors: Morishita Takami , Yoshida Hiroto , Ohshita Joji
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Regioselective Synthesis of 2,4‐(Dioxobutyl)dihydroquinolines and ‐pyridines by Chloroformiate‐Mediated Reaction of 1,3‐Bis(silyl enol ethers) with Quinolines and Pyridines.
Authors: Albrecht Uwe , Preuss Anja , Schmidt Andreas , Fischer Christine , Langer Peter
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Novel Convenient Synthesis of 5‐Acyl‐1,2‐dihydropyrimidin‐2‐ones via 4‐Trichloromethyl‐1,2,3,4‐tetrahydropyrimidin‐2‐ones.
Authors: Fesenko Anastasia A. , Solovyev Pavel A. , Shutalev Anatoly D.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Production of a New Type of Amidepsine with a Sugar Moiety by Static Fermentation of Humicola sp. FO‐2942.
Authors: Inokoshi Junji , Takagi Yoichi , Uchida Ryuji , Masuma Rokuro , Omura Satoshi , Tomoda Hiroshi
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Antipain Y, a New Antipain Analogue that Inhibits Neurotransmitter Release from Rat Dorsal Root Ganglion Neurons.
Authors: Nakae Koichi , Kojima Fukiko , Sawa Ryuichi , Kubota Yumiko , Igarashi Masayuki , Kinoshita Naoko , Adachi Hayamitsu , Nishimura Yoshio , Akamatsu Yuzuru
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Sonogashira Reactions of α‐ and β‐1‐Ethynyl‐2‐deoxyribosides: Synthesis of Acetylene‐Extended C‐Nucleosides.
Authors: Bobula Tomas , Hocek Michal , Kotora Martin
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Magnetic and Structural Properties of the Most Important Alloys of Iron Produced by Mechanical Alloying
Authors: Shokrollahi H.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Role of the Indole in Important Organocatalytic Enantioselective Friedel—Crafts Alkylation Reactions
Authors: Marques‐Lopez Eugenia , Diez‐Martinez Alba , Merino Pedro , Herrera Raquel P.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Recent Advances in the Mitsunobu Reaction. Modifications and Applications to Biologically Active Molecules
Authors: Reynolds A. J. , Kassiou M.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: anti‐Aging Studies on the Senescence Accelerated Mouse (SAM) Strains
Authors: Takahashi Ryoya
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structural Concepts of Novel Supramolecular Proton Transfer Compounds and Their Metal Complexes
Authors: Aghabozorg H. , Manteghi F. , Sheshmani S.
Published: May 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Experimental and theoretical study of gas hydrate formation in a high‐pressure flow loop
Authors: Sarshar Mohammad , Fathikalajahi Jamshid , Esmaeilzadeh Ferreidun
Published: May 2010

A set of mathematical models are developed based on thermodynamics, mass transfer, and crystallisation concepts to predict hydrate formation rate and the aqueous phase composition in the flow loop. In order to validate the model, experimental study is carried out in a 10 m loop with the inside diameter of 10.6 mm using gas mixture of 73% methane and 27% propane to measure the hydrate formation rate. The experimental conditions include temperature from 4 to 5°C and pressures between 2 and 3 MPa. Good agreements are noticed when the experimental and theoretical hydrate formation rates are compared at different operating conditions.
FEAST—realization of hardware‐oriented numerics for HPC simulations with finite elements
Authors: Turek Stefan , Göddeke Dominik , Becker Christian , Buijssen Sven H. M. , Wobker Hilmar
Published: May 2010

FEAST (Finite Element Analysis and Solutions Tools) is a Finite Element‐based solver toolkit for the simulation of PDE problems on parallel HPC systems, which implements the concept of ‘hardware‐oriented numerics’, a holistic approach aiming at optimal performance for modern numerics. In this paper, we describe this concept and the modular design that enables applications built on top of FEAST to execute efficiently, without any code modifications, on commodity‐based clusters, the NEC SX 8 and GPU‐accelerated clusters. We demonstrate good performance and weak and strong scalability for the prototypical Poisson problem and more challenging applications from solid mechanics and fluid dynamics. Copyright © 2010 John Wiley & Sons, Ltd.
A comparison between taste avoidance and conditioned disgust reactions induced by ethanol and lithium chloride in preweanling rats
Authors: Arias Carlos , Pautassi Ricardo Marcos , Molina Juan Carlos , Spear Norman E.
Published: May 2010

Adult rats display taste avoidance and disgust reactions when stimulated with gustatory stimuli previously paired with aversive agents such as lithium chloride (LiCl). By the second postnatal week of life, preweanling rats also display specific behaviors in response to a tastant conditioned stimulus (CS) that predicts LiCl‐induced malaise. The present study compared conditioned disgust reactions induced by LiCl or ethanol (EtOH) in preweanling rats. InExperiment 1we determined doses of ethanol and LiCl that exert similar levels of conditioned taste avoidance. After having equated drug dosage in terms of conditioned taste avoidance, 13‐day‐old rats were given a single pairing of a novel taste (saccharin) and either LiCl or ethanol (2.5 g/kg; Experiment 2). Saccharin intake and emission of disgust reactions were assessed 24 and 48 hr after training. Pups given paired presentations of saccharin and the aversive agents (ethanol or LiCl) consumed less saccharin during the first testing day than controls. These pups also showed more aversive behavioral reactions to the gustatory CS than controls. Specifically, increased amounts of grooming, general activity, head shaking, and wall climbing as well as reduced mouthing were observed in response to the CS. Conditioned aversive reactions but not taste avoidance were still evident on the second testing day. In conclusion, a taste CS paired with postabsorptive effects of EtOH and LiCl elicited a similar pattern of conditioned rejection reactions in preweanling rats. These results suggest that similar mechanisms may be underlying CTAs induced by LiCl and a relatively high EtOH dose. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 545–557, 2010.
The ontogeny of anxiety‐like behavior in rats from adolescence to adulthood
Authors: Lynn Debra A. , Brown Gillian R.
Published: May 2010

In human beings, susceptibility to anxiety disorders can be relatively high during adolescence. Understanding the ontogeny of anxiety‐like behavior in laboratory rodents has implications for developing anxiolytic drugs that are suitable for this age group. Given the dearth of information about adolescent rodents, this study examined the response of both male and female adolescent, late adolescent, young adult, and older adult rats to three tests of anxiety‐like behavior: the emergence test (ET), open field (OF), and elevated plus‐maze (EPM). The results showed that adolescent rats exhibited a higher anxiety‐like response than adults on each test; the amount of locomotion in the OF and percentage of time spent on the open arms of the EPM increased across the age groups, while older adult rats made the fewest start box re‐entries in the ET. These results support the hypothesis that adolescent rats have a more pronounced response to stressors than do adults. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 731–739, 2010.
Ruthenium(II) Complexes of Carboxylated Terpyridines and Dipyrazinylpyridines
Authors: Stublla Arta , Potvin Pierre G.
Published: May 2010

One‐pot preparations of carboxylated 2,2′;6′,2″‐terpyridine and 2,6‐dipyrazin‐2‐ylpyridine ligands are reported in free acid and ester forms, as well as their transformations to homoleptic RuII complexes in very good yields. Density functional theory calculations of their geometry‐optimized structures enabled their comparison with crystal structures; although the gross features of the crystal structures were reproduced, they showed much variability and distortion. The spectroscopic and electrochemical properties were analyzed from the point of view of their geometry‐optimized structures, molecular orbital characteristics and electronic transitions, specifically to assess the effects of carboxylation and of inserting a phenylene spacer between the tridentate portion and the carboxyl group. The dipyrazinylpyridine complexes had HOMO levels stabilized by approximately 1 eV relative to the terpyridine analogues, and showed positive‐shifted electrochemical potentials and redshifted electronic absorptions. Phenylene spacers were found to act as electron‐donating groups, and the lowest‐energy UV/Vis transitions showed intraligand character.
Competing Regiodirecting Effects of Ester and Aryl Groups in [3+3] Cyclocondensations of 1,3‐Bis(trimethylsilyloxy)‐1,3‐butadienes: Regioselective Synthesis of 3‐Hydroxyphthalates and 2‐Hydroxyterephthalates
Authors: Shkoor Mohanad , Fatunsin Olumide , Riahi Abdolmajid , Lubbe Mathias , Reim Stefanie , Sher Muhammad , Villinger Alexander , Fischer Christine , Langer Peter
Published: May 2010

3‐Hydroxy‐5‐methylphthalates are prepared by regioselective chelation‐controlled cyclization of 1,3‐bis(silyloxy)‐1,3‐butadienes with 4‐silyloxy‐2‐oxo‐3‐butenoates derived from acetylpyruvates. The employment of silylated benzoylpyruvates instead of acetylpyruvates results in a regioselectivity change and the formation of 6‐aryl‐2‐hydroxyterephthalates. The cyclization of 1,3‐bis(silyloxy)‐1,3‐butadienes with 4‐ethoxy‐2‐oxo‐3‐butenoates, readily available by condensation of enol ethers with methyl 2‐chloro‐2‐oxoacetate, provides a convenient approach to 2‐hydroxyterephthalates and 3‐hydroxyphthalates depending on the substitution pattern of the diene.