bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation curing of collagen/divinyl ether enhanced by pyridinium salts
Authors: Jiang Bo , Zhou Yong , Yang Zheng , Wu Zhihong , Huang Guanglin , Lin Libin , Zhang Xingdong 
Published: September 2005

AbstractThe radiation curings of collagen/divinyl ether enhanced by several nitrogenous onium salts having relatively stable nonnucleophilic anion (PF6−) have been investigated. Results of glass transformation temperature (Tg) measurements and IR spectroscopy analysis and solvent extractions to the crosslinked polymer networks demonstrate that the curing reactions have been initiated by electron beam irradiation in the mixture system of collagen/divinyl ether and onium salts under different atmosphere conditions. The experimental data show the presence of an approximating linear relationship between double bond conversion and gel fraction after the calculation of conversion from IR spectra in oligomer and the measure of gel content at different total radiation doses. Practical values approximate theoretical values in applying gelation theory of the relationship of gel fraction and double bond conversion. In comparison with the influence of different inhibitors, the curing reaction with pyridinium salts is a polymerization and crosslinking of cationic mechanism, but radicals play an important role in initiation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2094–2100, 2005
Influence of bound polymer on cure characteristics of natural rubber compounds reinforced with different types of carbon blacks
Authors: Choi Sung‐Seen , Hwang Ki‐Jun , Kim Beom‐Tae 
Published: September 2005

AbstractRubber compounds are reinforced with fillers such as carbon black and silica. The cure characteristics of a filled rubber compound vary with the filler type and content. The influence of the type of carbon black on the cure characteristics of carbon black filled natural rubber compounds is investigated using two types of carbon black (N220 and N550), which are different in primary size and structure. The cure time and cure rate become faster as the carbon black content increases. The crosslink density also increases and reversion resistance is improved with the increase of carbon black content. The cure time and cure rate of the compound filled with N550 are faster than those of the compound filled with N220 at the same level of bound rubber content. In addition, higher crosslink density is also observed in the compound filled with N550 compared to that of the compound filled with N220 at the same level of bound rubber content. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2282–2289, 2005
Synthesis and characterization of poly(n‐butyl methacrylate)‐b‐polystyrene diblock copolymers by atom transfer radical emulsion polymerization
Authors: Peng Hui , Cheng Shiyuan , Fan Zhiqiang 
Published: September 2005

AbstractPoly(n‐butyl methacrylate) (PBMA)‐b‐polystyrene (PSt) diblock copolymers were synthesized by emulsion atom transfer radical polymerization (ATRP). PBMA macroinitiators that contained alkyl bromide end groups were obtained by the emulsion ATRP of n‐butyl methacrylate with BrCH3CHCOOC2H5 as the initiator; these were used to initiate the ATRP of styrene (St). The latter procedure was carried out at 85°C with CuCl/4,4′‐di(5‐nonyl)‐2,2′‐bipyridine as the catalyst and polyoxyethylene(23) lauryl ether as the surfactant. With this technique, PBMA‐b‐PSt diblock copolymers were synthesized. The polymerization was nearly controlled; the ATRP of St from the macroinitiators showed linear increases in number‐average molecular weight with conversion. The block copolymers were characterized with IR spectroscopy, 1H‐NMR, and differential scanning calorimetry. The effects of the molecular weight of the macroinitiators, macroinitiator concentration, catalyst concentration, surfactant concentration, and temperature on the polymerization were also investigated. Thermodynamic data and activation parameters for the ATRP are also reported. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2123–2129, 2005
Electrical conductivity and electromagnetic interference shielding of polyaniline/polyacrylate composite coatings
Authors: Jing Xinli , Wang Yangyong , Zhang Baiyu 
Published: September 2005

AbstractLightweight and flexible composite coatings of p‐toluene sulfonic acid doped polyaniline (PANI–TSA) with various mass fractions and polyacrylate were prepared for electromagnetic interference (EMI) shielding. Both the volume and surface conductivities of the composite coatings increased with increasing PANI–TSA; furthermore, the volume conductivity showed a typical percolation behavior with a percolation threshold at about 0.21. The EMI shielding effectiveness (SE) of the PANI–TSA/polyacrylate coatings over the range of 14 kHz to 15 GHz increased with increasing PANI–TSA as the direct‐current conductivity did. EMI SE of the coatings at the low frequencies (14 kHz to 1 GHz) was around 30–80 dB, higher than that at the high frequencies (1–15 GHz); this indicated possible commercial application of the coatings for far‐field EMI shielding. The highest EMI SE value was 79 dB at 200 MHz with a coating thickness of 70 ± 5 μm. The moderate SE, light weight, and easy preparation of the coating are advantages for future applications for EMI shielding. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2149–2156, 2005
Study of the morphology and kinetics of novel Ziegler–Natta catalysts for propylene polymerization
Authors: Abboud Mohammed , Denifl Peter , Reichert Karl‐Heinz 
Published: September 2005

AbstractThe morphological and kinetic characteristics of novel Ziegler–Natta catalysts were studied. Catalysts were prepared by Borealis Polymers Oy using a new synthesis technique (emulsion technology). Video microscopy was used to study the growth of single catalyst particles during polymerization in the gas and liquid phases. The distribution of single particle activity was very narrow in the catalyst without external support and was rather broad in the the silica‐supported catalyst. Video microscopy of molten polymer particles allowed observation of the process and degree of fragmentation of the catalyst particles. A correlation between the activation period during the initial stage of polymerization and catalyst fragmentation was found. Fragmentation was faster and more uniform with the catalyst without external support than with the silica‐supported catalyst. Scanning electron microscopy provided information on morphology evolution and shape replication of the catalyst particles. With the catalyst without external support, good shape replication was observed, and compact and spherical particles were formed. With the silica‐supported catalyst, shape replication was poor, and nonspherical porous polymer particle were formed. Modeling of the kinetics of propylene polymerization was done using a simple three‐step reaction scheme neglecting mass and heat transport effects. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2191–2200, 2005
Effect of some water‐soluble melamine formaldehyde‐free polycondensates on the rheological properties of cement pastes
Authors: Aiad Ismail 
Published: September 2005

AbstractWater‐soluble melamine formaldehyde‐free polycondensate products were prepared. The chemical structure of these polymers was confirmed with different spectroscopic techniques. The effects of these polymers on the rheological properties of the cement pastes were investigated. The rheological parameters (shear stress, yield stress, and plastic viscosity) were calculated with the Bingham model. The minislump of superplasticized cement pastes at different interval times (5, 30, 60, 90, and 120 min) was determined. The results showed that the new superplasticizers increased the fluidity and minislump of the cement pastes and reduced the minislump loss of the cement pastes not only at early ages (30 min) but also at later early ages (120 min). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2212–2218, 2005
Mechanism of dielectric‐barrier discharge initiated wet‐strength development
Authors: Vander Wielen L. C. , Östenson M. , Gatenholm P. , Ragauskas A. J. 
Published: September 2005

AbstractThe fundamental mechanism of wet‐strength development for dielectric‐barrier discharge treated thermomechanical pulp fibers was explored. Electron spectroscopy for chemical analysis (ESCA), vapor phase fluorine surface derivatization followed by ESCA, and dynamic contact angle analysis were performed to assess the surface chemistry in terms of both chemical functionality and wettability. Effects of the intensity of dielectric‐barrier discharge treatment on the surface chemistry of lignocellulosic fibers and the corresponding impacts to fiber wet‐tensile properties are described. This study indicates that low treatment intensities result in increased wettability due to surface oxidation, which leads to a small reduction in wet‐tensile index. However, increased treatment intensity brings about diminished wettability due to covalent crosslinking, which leads to increases in wet‐tensile index. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2219–2225, 2005
Comparison of four non‐hydrostatic models for flow over the Isle of Arran
Authors: Al‐Maskari Juma , Gadian Alan M. 
Published: September 2005

AbstractFour non‐hydrostatic atmospheric models were compared for a case study of southerly airflow over the Isle of Arran in Scotland. The model results are contrasted with each other and aircraft wind observations. All resolve qualitatively similar the background gravity wave flow, despite different formulations. Copyright © 2005 Royal Meteorological Society
Application of an electric DNA‐chip for the expression analysis of bioprocess‐relevant marker genes of Bacillus subtilis
Authors: Jürgen Britta , Barken Kim Bundvig , Tobisch Steffen , Pioch Daniel , Wümpelmann Mogens , Hecker Michael , Schweder Thomas 
Published: September 2005

AbstractThe knowledge of critical process‐relevant genes can be used for an improved control of bioprocesses. So far bioprocess‐relevant marker genes can be analyzed by established expression analysis methods only off‐line. In this study, an alternative approach for a potential at‐line monitoring of gene expression during bioprocesses is suggested. This approach is based on the measurement of specific mRNAs on an electric DNA‐chip in connection with a magnetic bead‐based sandwich hybridization. In order to allow an at‐line measurement of specific mRNAs an improved method for a fast and partially automated isolation of high quality‐RNA samples was developed. The expression analysis of the electric DNA‐chip was compared with optical DNA micro arrays and the real time RT‐PCR for three selected process‐relevant genes of Bacillus subtilis. We demonstrate that the mRNA analysis by means of the electric DNA‐chip gives similar results compared to the micro array analysis and the real time RT‐PCR technique. © 2005 Wiley Periodicals, Inc.
Differentiation and lineage selection of mouse embryonic stem cells in a stirred bench scale bioreactor with automated process control
Authors: Schroeder Magnus , Niebruegge Sylvia , Werner Andreas , Willbold Elmar , Burg Monika , Ruediger Manfred , Field Loren J. , Lehmann Juergen , Zweigerdt Robert 
Published: September 2005

AbstractIt is well established that embryonic stem (ES) cells can differentiate into functional cardiomyocytes in vitro. ES‐derived cardiomyocytes could be used for pharmaceutical and therapeutic applications, provided that they can be generated in sufficient quantity and with sufficient purity. To enable large‐scale culture of ES‐derived cells, we have developed a robust and scalable bioprocess that allows direct embryoid body (EB) formation in a fully controlled, stirred 2 L bioreactor following inoculation with a single cell suspension of mouse ES cells. Utilizing a pitched‐blade‐turbine, parameters for optimal cell expansion as well as efficient ES cell differentiation were established. Optimization of stirring conditions resulted in the generation of high‐density suspension cultures containing 12.5 × 106 cells/mL after 9 days of differentiation. Approximately 30%–40% of the EBs formed in this process vigorously contracted, indicating robust cardiomyogenic induction. An ES cell clone carrying a recombinant DNA molecule comprised of the cardiomyocyte‐restricted alpha myosin heavy chain (αMHC) promoter and a neomycin resistance gene was used to establish the utility of this bioprocess to efficiently generate ES‐derived cardiomyocytes. The genetically engineered ES cells were cultured directly in the stirred bioreactor for 9 days, followed by antibiotic treatment for another 9 days. The protocol resulted in the generation of essentially pure cardiomyocyte cultures, with a total yield of 1.28 × 109 cells in a single 2 L bioreactor run. This study thus provides an important step towards the large‐scale generation of ES‐derived cells for therapeutic and industrial applications. © 2005 Wiley Periodicals, Inc.
Determination of the endocannabinoid anandamide in human plasma by high‐performance liquid chromatography
Authors: Schmidt Andreas , Brune Kay , Hinz Burkhard 
Published: September 2005

AbstractAnandamide (N‐arachidonylethanolamine) is an endogenous cannabinoid receptor ligand that has been implicated in various physiological and pathophysiological functions. In the present study, a liquid–liquid extraction‐based reversed‐phase HPLC method with fluorometric detection was validated and applied for the analysis of anandamide in human plasma. Following derivatization with the fluorogenic reagent 4‐(N,N‐dimethylaminosulfonyl)‐7‐(N‐chloroformylmethyl‐N‐methyl‐amino)‐2,1,3‐benzoxadiazole (DBD‐COCl), the analyte was separated using an acetonitrile–water gradient at a flow rate of 0.8 mL/min, and spectrophotometric detection at 560 nm with an excitation wavelength of 450 nm. The retention times for anandamide and R(+)‐methanandamide (internal standard) were 27.1 and 30.7 min, respectively. The validated quantification range was 1–15 ng/mL. The developed procedure was applied to determine anandamide levels in human plasma following a 24 h incubation of human whole blood at 37°C in the presence or absence of phenylmethylsulfonyl fluoride, an inhibitor of the anandamide‐degrading enzyme fatty acid amide hydrolase. Anandamide levels determined under both conditions were within the validated concentration range with anandamide levels being 2.3‐fold higher in plasma from PMSF‐treated blood. Copyright © 2005 John Wiley & Sons, Ltd.
Comparative evaluation of hepatotoxic and nephrotoxic effects of aroclors 1221 and 1254 in female rats
Authors: Kutlu Selim , Colakoglu Neriman , Halifeoglu Ihsan , Sandal Suleyman , Seyran Ayse D. , Aydin Mehmet , Yılmaz Bayram 
Published: September 2005

AbstractPolychlorinated biphenyls (PCBs) are persistent environmental pollutants. This study compared effects of two PCB mixtures, Aroclors 1221 (A1221) and 1254 (A1254) on serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea, creatinine and uric acid in female rats. Histopathological changes in the liver and kidney were also examined. A group of adult Wistar rats served as controls. Groups II and III were subcutaneously injected with A1221 and A1254 at 10 mg/kg every other day for 6 weeks. At the end of this period, all animals were decapitated and blood samples were collected. Serum urea, creatinine, uric acid, ALT, AST and ALP levels were determined. Liver and kidney were collected for histopathological examination. They were fixed in formaldehyde and processed for light microscopy. Both A1221 and 1254 significantly elevated serum ALT (p < 0.05) and AST (p < 0.01) levels compared to the control group. Serum ALP values were significantly increased by A1221 (p < 0.05), but they were unaffected in the A1254 group. Treatment with both A1221 and A1254 significantly increased serum levels of urea (p < 0.05), creatinine (p < 0.01) and uric acid (except in the A1221 group; p < 0.005). Distinct histopathological changes including renal corpuscular atrophy, peritubular vascular congestion and dilated cortical tubules, sinusoidal dilatation, congestion and mononuclear cell infiltration were observed. These findings suggest that PCBs may cause nephrotoxicity and hepatotoxicity in female rats. Copyright © 2005 John Wiley & Sons, Ltd.
Synthesis and Structural Characterization of Neutral Higher‐Coordinate Silicon(iv) Complexes with Tridentate Dianionic Chelate Ligands
Authors: Seiler Oliver , Burschka Christian , Metz Stefan , Penka Martin , Tacke Reinhold 
Published: September 2005

AbstractThe neutral pentacoordinate silicon(iv) complexes 8 and 9 with an SiO2N3 skeleton and the neutral hexacoordinate silicon(iv) complex 10⋅ 1/2 CH3CN with an SiO4N2 skeleton were synthesized, starting from tetra(cyanato‐N)silane or tetra(thiocyanato‐N)silane. Compounds 8 and 9 contain one tridentate dianionic ligand derived from 4‐[(2‐hydroxyphenyl)amino]pent‐3‐en‐2‐one and two monodentate singly charged cyanato‐N or thiocyanato‐N ligands bound to the silicon(iv) coordination center, whereas the silicon(iv) center of 10 is coordinated by two of these tridentate dianionic ligands. All compounds were characterized by single‐crystal X‐ray diffraction and solid‐state and solution NMR spectroscopy. To get more information about the stereochemistry of the compounds studied, the experimental investigations were complemented by computational studies.
A New Tool in Peptide Engineering: A Photoswitchable Stilbene‐type β‐Hairpin Mimetic
Authors: Erdélyi Máté , Karlén Anders , Gogoll Adolf 
Published: September 2005

AbstractPeptide secondary structure mimetics are important tools in medicinal chemistry, as they provide analogues of endogenous peptides with new physicochemical and pharmacological properties. The development, synthesis, photochemical investigation, and conformational analysis of a stilbene‐type β‐hairpin mimetic capable of light‐triggered conformational changes have been achieved. In addition to standard spectroscopic techniques (nuclear Overhauser effects, amide temperature coefficients, circular dichroism spectroscopy), the applicability of self‐diffusion measurements (longitudinal eddy current delay pulsed‐field gradient spin echo (LED‐PGSE) NMR technique) in conformational studies of oligopeptides is demonstrated. The title compound shows photoisomerization of the stilbene chromophore, resulting in a change in solution conformation between an unfolded structure and a folded β‐hairpin.
Probing the “additive effect” in the proline and proline hydroxamic acid catalyzed asymmetric addition of nitroalkanes to cyclic enones
Authors: Hanessian Stephen , Govindan Subramaniyan , Warrier Jayakumar S. 
Published: September 2005

AbstractThe effect of chirality and steric bulk of 2,5‐disubstituted piperazines as additives in the conjugate addition of 2‐nitropropane to cyclohexenone, catalyzed by l‐proline, was investigated. Neither chirality nor steric bulk affects the enantioselectivity of addition, which gives 86–93% ee in the presence of achiral and chiral nonracemic 2,5‐disubstituted piperazines. Proline hydroxamic acid is shown for the first time to be an effective organocatalyst in the same Michael reaction. © 2005 Wiley‐Liss, Inc. Chirality 17:540–543, 2005.
Calculated absorption and vibrational circular dichroism spectra of fundamental and overtone transitions for a chiral HCCH molecular fragment in the hypothesis of coupled dipoles
Authors: Gangemi Roberto , Longhi Giovanna , Abbate Sergio 
Published: September 2005

AbstractWe establish the general behavior of absorption and vibrational circular dichroism spectra (VCD) of a chiral HCCH fragment lacking all symmetry elements; the study is limited to CH‐stretching modes, and the Hamiltonian employed is written in terms of normal‐mode coordinates and momenta and approximates two different Morse oscillators interacting through a harmonic coupling term; rotational strengths are evaluated within a hypothesis of coupled electric dipoles. Van Vleck contact transformations written in terms of raising and lowering operators are used to calculate spectra up to the manifold Δv = 4. Three transformations are necessary to obtain fourth‐order terms in the relevant operators, namely, the electric and magnetic dipole moments. The dynamics of the system exhibits 1:1 resonance terms in addition to the Darling–Dennison coupling term. We discuss the importance of coupling between CH stretches with respect to differences in their local mechanical characteristics in determining the aspect of the absorption and VCD fundamental and overtone spectra of increasing quantum number. © 2005 Wiley‐Liss, Inc. Chirality 17:530–539, 2005.
Dust Ion‐Acoustic Shocks in a Q Machine Device
Authors: Popel S. I. , Losseva T. V. , Golub' A. P. , Merlino R. L. , Andreev S. N. 
Published: September 2005

AbstractDust ion‐acoustic shocks in a Q machine device are considered. For their description the so‐called hydrodynamic ionization source model is used. The model is appropriate for the description of the laboratory experiments in a Q machine device and contains the most important basic mechanisms responsible for the formation of the dust ion‐acoustic shocks. A comparative analysis of various dissipative processes occurring on ion‐acoustic time scales during the excitation and propagation of nonlinear dust ion‐acoustic perturbations in a complex (dusty) plasma is performed in terms of a purely kinetic approach and a hydrodynamic approach. It is found that the most important dissipative processes are the charging of dust grains, the absorption of ions by grains, the transfer of the ion momentum to the grains, and Landau damping. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Presheath in Fully Ionized Collisional Plasma in a Magnetic Field
Authors: Alterkop B. , Goldsmith S. , Boxman R. L. 
Published: September 2005

AbstractThe quasineutral presheath layer at the boundary of fully ionized, collisional, and magnetized plasma with an ambipolar flow to an adjacent absorbing wall was analyzed using a two fluid magneto‐hydrodynamic model. The plasma is magnetized by a uniform magnetic field B, imposed parallel to the wall. The analysis did not assume that the dependence of the particle density on the electric potential in the presheath is according to the Boltzmann equilibrium, and the dependence of the mean collision time τ on the varying plasma density within the presheath was not neglected. Based on the model equations, algebraic expressions were derived for the dependence of the plasma density, electron and ion velocities, and the electrostatic potential on the position within the presheath. The solutions of the model equations depended on two parameters: Hall parameter (β ), and the ratio (γ ), where γ = ZTe /(ZTe + Ti ), and Te , Ti and Z are the electron and ion temperatures and ionicity, respectively. The characteristic scale of the presheath extension is several times ri /β , where ri is the ion radius at the ion sound velocity. The electric potential could have a non monotonic distribution in the presheath. The ions are accelerated to the Bohm velocity (sound velocity) in the presheath mainly near the presheath‐sheath boundary, in a layer of thickness ∼ri /β . The electric field accelerates the ions in the whole presheath if their velocity in the wall direction exceeds their thermal velocity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calculated Electron Impact Ionization Cross Sections of Excited Ne Atoms Using the DM Formalism
Authors: Deutsch H. , Becker K. , Grum‐Grzhimailo A. N. , Probst M. , Matt‐Leubner S. , Märk T. D. 
Published: September 2005

AbstractWe used the semi‐classical Deutsch‐Märk (DM) formalism to calculate absolute electron‐impact ionization cross sections of excited Ne atoms from threshold to 1000 eV. Excited states of Ne where the outermost valence electron is excited to states with principal quantum numbers up to n = 7 and orbital angular momentum quantum numbers up to l = 2 have been considered and systematic trends in the calculated cross section data are discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)