bluuebunny/crossref_metadata_2025 huggingface dataset:
Heck and Suzuki–Miyaura couplings catalyzed by nanosized palladium in polyaniline
Authors: Houdayer Axel , Schneider Raphaël , Billaud Denis , Ghanbaja Jaafar , Lambert Jacques
Published: November 2005

A novel route to prepare polyaniline (PANI)‐supported Pd(0) nanoparticles by a one‐pot chemical route is presented. Nanosized Pd(0) particles were first prepared by reduction of Pd(OAc)2 using t‐BuONa activated sodium hydride in refluxing THF. A ligand exchange with aniline on t‐BuONa‐stabilized Pd(0) particles yielded aniline‐stabilized particles. Pd(0)/PANI nanocomposites were finally obtained by polymerizing aniline‐stabilized Pd(0) particles using ammonium persulfate. Nanocomposites were characterized by transmission electron microscopy, X‐ray diffraction and X‐ray photoelectron spectroscopy. Results show that this one‐pot experimental route is successful in producing hybrid materials constituted of Pd(0) nanoparticles stabilized by PANI due to the strong binding of PANI amine groups to Pd(0) particles. TEM images of the nanohybrids show that metal particles with diameters of ca. 4.9 nm are homogeneously dispersed in PANI. The preliminary results indicate that the Pd(0) particles supported on PANI behave as efficient heterogeneous catalysts in the Heck and Suzuki–Miyaura reactions of aryl iodides. Copyright © 2005 John Wiley & Sons, Ltd.
Graft copolymerization of glycidylmethacrylate onto modified nylon‐6 fibers
Authors: Shalaby S. E. , Al‐Balakocy N. G. , Abo El‐Ola S. M.
Published: November 2005

The graft copolymerization of glycidylmethacrylate (GMA) onto modified nylon‐6 fibers containing polydiallyldimethylammonium chloride (PDADMAC) groups in the presence of (Cu 2+–K2S2O8) as a redox initiating system was carried out, with very high extent and almost without homopolymer formation. The mechanism of the graft polymerization induced by this system was suggested. The rate of grafting was determined by varying the monomer, K2S2O8, and cupric ion concentrations as well as the amount of PDADMAC. The kinetic investigation revealed that the rate of grafting (Rp) of GMA onto modified nylon‐6 fibers is proportional to [GMA]1.83, [CuSO4·5H2O]0.46, [PDADMAC]0.4, and [K2S2O8]1.43. The overall activation energy was 134.7 kJ/mol. The fine structure and thermal properties of the grafted nylon‐6 fibers were investigated. investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 613–618, 2006
Preparation and properties of borosiloxane gels
Authors: Wang Qian , Fu Liying , Hu Xiaowen , Zhang Zhijie , Xie Zemin
Published: November 2005

Hybrid gels were synthesized from modified silicon alkoxides (R‐Si(OEt)3, RH, Me, Vi) and triiso‐butylborate (B(OR′)3, R′ = isoBu). The obtained gels were characterized by Fourier‐transform infrared (FTIR), nuclear magnetic resonance (NMR), elemental analyses, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Boron atoms in the precursors were homogeneously dispersed in the siloxane network via SiOB bonds. The effect of the boron load on oxidation resistance of the gels, and the pyrolysis behavior of the borosiloxane gels with different substituents on silicon, were investigated using various techniques. The experimental results suggest that the addition of a proper fraction of boron alkoxide to the precursors can improve the oxidation stability of the gels, and decrease the weight loss of the samples to 6.9 wt % at 1000°C under air. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 719–724, 2006
Synthesis of multi‐arm star polystyrene with hyperbranched polyester initiators by atom transfer radical polymerization
Authors: Jiang Guohua , Wang Li , Chen Tao , Chen Chang , Yu Haojie
Published: November 2005

Multi‐arm star polystyrenes with hyperbranched polyester (HP3) core were prepared by atom transfer radical polymerization (ATRP). The structures of the polymers were investigated with FTIR and 1H NMR. GPC results showed that the resultant polymers had relatively broad polydispersity indices that arouse from the macromolecular initiator (HP3‐Br). The thermal properties were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC analysis indicated that polystyrene star polymers had only the glass transition temperatures (Tg), which changes with the weight ratio of multi‐functional macroinitiator‐to‐monomer. In addition, these star polymers could form the spherical micelles in the selected solvent (THF/n‐hexane). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 728–733, 2006
Study on the surface grafting of polypropylene fibers
Authors: Wang W. , Wang L. , Wang C. L. , Sun T. X. , Yu H. J. , Chen T.
Published: November 2005

In this article, the surfaces of polypropylene (PP) fibers were grafted by three different grafting systems, of which the initiators belonged to three different types, namely, the water‐soluble initiator, the redox initiator, and the oil‐soluble initiator, respectively. The grafted products were characterized by FTIR, and the grafting degrees were determined by acid–base titration. In comparison, it was found that the oil‐soluble initiator might be more suitable for the surface grafting modification of PP fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 734–737, 2006
An ESR study of the radiolysis of semi‐crystalline ethylene‐propylene copolymers containing DOP mobilizer
Authors: Fuzail Mohammad , Hill David J. T. , Le Tri T.
Published: November 2005

The radiolysis of a poly(ethylene‐co‐propylene), Elpro, marketed by Thai Polypropylene Co. Ltd for the manufacture of medical goods has been investigated at 77 K. Calcium stearate was blended with the Elpro as a processing aid; and dioctyl phthalate, DOP, was added in various amounts as a radiation stabilizer. The ESR spectra of Elpro and Elpro+Ca were very similar and characterized principally by the presence of PP α‐carbon radicals. The spectra of the samples containing DOP were similar to those for Elpro but with an additional narrow singlet arising from DOP radicals. On annealing the irradiated polymers to higher temperatures, the singlet was lost between 250 and 270 K, and at room temperature the principal radicals remaining were allyl radicals. The G‐values for radical formation at 77 K for Elpro and Elpro+Ca at 77 K were 3.0 and 3.2, respectively, but incorporation of DOP resulted in lower G‐values, ranging from 1.6 to 1.4 for 0.5 and 2.5 phr DOP, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 638–643, 2006
Vinyl ester resin modified with silicone‐based additives: II. Flammability properties
Authors: Mazali Cristiana A. Ittner , Felisberti Maria Isabel
Published: November 2005

Silicone‐based additives have been used as fire retardants for thermoplastics, presenting the advantages of improving processing and impact resistance of the polymers. In this work we used three different silicone‐based additives as modifiers of a thermoset based on a vinyl ester resin. The additives are fine powders made up of about 50 wt % ultra high molecular weight polydimethylsiloxane and 50 wt % silica. The differences between them are the functional groups inserted on the additives and the size and size distribution of the particles. The additives were dispersed in resin containing 35 wt % of styrene. For curing the mixture a conventional catalyst and initiator were used and the reaction was carried out in two ways, differing in the curing temperature, the post curing temperature, and the time, and in the addition of dimethylaniline (DMA) as a promoter of the polyaddition reaction. The samples were characterized by thermogravimetric analyses and swelling experiments. The fire retardances of the samples were evaluated by the determination of the flash‐ignition, self‐ignition, and pyrolysis temperatures (ASTM D1919–91a), and of the oxygen index (ASTM D‐2863–91). The results obtained showed that the silicone‐based additives and the methods used in the preparation of the modified resin influence the flash‐ignition, self‐ignition, and pyrolysis temperatures, but not the oxygen index. Samples cured by different methods present different network characteristics, which influence their thermal decomposition. The volatile species produced by thermal decomposition may be a combination of inert and active species. The network structure may influence only the inert fraction of the volatiles, not the combustibles. These volatile inert species (smoke‐black, water vapor, carbon dioxide, etc.) probably dilute the combustibles in the solid and in the gaseous phase, increasing the flash‐ignition temperature of the samples. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 644–649, 2006
Correlation between viscoelastic behavior and cooling stresses in a cured epoxy resin system
Authors: Nassiet V. , Habas J. P. , Hassoune‐Rhabbour B. , Baziard Y. , Petit J. A.
Published: November 2005

This work deals with the study of the rheological behavior of an epoxy system subjected to three cooling processes referred to as the normal, air‐, and water‐cooling processes. The system was set up by a difunctional epoxy resin (DGEBA) mixed with a tetrafunctional diamine (mPDA) in stoichiometric proportions. Different samples of (1) neat and cured polymers and (2) alumina—epoxy composites were prepared. The first part of this work was devoted to optimizing the cure cycle of the neat samples using differential scanning calorimetry and rheometry. The best cure cycle is based on a first heat step at 110°C during 10 min followed by a crosslinking stage of 75 min at 180°C. In the second part of the study the influence of the cooling cycle on the thermomechanical behavior of polymer and composite samples was investigated. Measurement of loss modulus, G″, and loss factor, tan δ, versus temperature showed that an intermediate relaxation α′ peak arose between the main and secondary relaxations (resp. α and β). The position and amplitude of the α′ peak increased with the cooling rate. This rheological phenomenon is related to the presence of nonequilibrium stresses frozen in the sample during cooling. The effect of thermal aging on the α′ peak also is reported. Our work also showed the presence of an α′ peak for the composites. However, the amplitude of this peak was more pronounced in the composites because of additional stresses induced by the difference between the resin and the ceramic in thermal expansion coefficients. We showed that a calculation based on a thermoelastic model was useful for qualitative comparison of rheological data on the influence of the cooling process. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 679–690, 2006
Development of a novel microorganism immobilization method using anionic polyurethane
Authors: Lin Yun‐Huin , Hwang Sz‐Chwun John , Shih Wen‐Chang , Chen Kuo‐Cheng
Published: November 2005

A new microorganism immobilization method involving gelation of anionic polyurethane has been developed. Nontoxic synthetic anionic polyurethane was used, which provides greater mechanical strength than do natural polymers. Similar to the formation of Ca‐alginate gel beads, this method has the advantage of easy preparation. Gel beads are formed only by dropping the anionic polyurethane emulsion into a calcium chloride solution. The feasibility of the proposed immobilization method was tested by an ethanol production process with baker's yeast (Saccharomyces cerevisiae). The result verified that the anionic polyurethane entrapped–cell method developed in this study has great potential for a variety of applications such as biological processes and biological wastewater treatment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 738–743, 2006
Study on the grafting of PET onto the glass fiber surface during in situ solid‐state polycondensation
Authors: Yan Weixia , Han KeQing , Zhou Hongmei , Yu MuHuo
Published: November 2005

An in situ solid‐state polymerization process was developed to produce long glass fiber reinforced poly(ethylene terephthalate) (PET) composites. As reported in our last article, one advantage of this new process is that the good wetting of reinforcing fiber can be obtained for using low‐viscosity oligomer as raw materials. In this article, the grafting of PET macromolecular chain onto the surface of reinforcing glass fiber during in situ solid‐state polycondensation (SSP) will be investigated, which was believed to be another advantage for this new process and should be very important for thermoplastic composite. The reinforcing glass fiber after removing ungrafted PET from a long glass fiber reinforced PET composite by solvent extraction was investigated by SEM, pyrolysis‐gas chromatography mass spectrometry (Py‐GC/MS), DSC, and FTIR. The information from morphology of SEM photos of glass fiber surface, the spectrum of Py‐GC/MS, the melt peak at differential scanning calorimetric (DSC) curve, and the spectrum of Fourier transform infrared Raman spectroscopy (FTIR) gave a series evidence to prove the presence of grafted PET layer on the surface of silane‐coupling‐treated glass fiber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 775–781, 2006
Fabrication and characterization of biodegradable poly(propylene carbonate)/wood flour composites
Authors: Ge X. C. , Zhu Q. , Meng Y. Z.
Published: November 2005

Wood flour reinforced poly(propylene carbonate) (PPC) composites were prepared by melt blending followed by compression molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, and thermal properties of PPC/wood flour composites were investigated. In terms of mechanical properties, wood flour had the significant effect of improving tensile strength and stiffness. Scanning electron microscopic examination revealed good dispersion of wood flour (especially at lower content) in the PPC matrix. Moreover, experimental results indicated that the wood flour addition led to an obvious improvement in the thermal stability of the composites. This paper demonstrates that the incorporation of low‐cost and biodegradable wood flour into PPC provides a practical way to produce completely biodegradable and cost‐competitive composites with good mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 782–787, 2006
Effect of water‐soluble monomers on emulsifier‐minor emulsion polymerization of butylacrylate–methacrylic acid–styrene and properties of the latices
Authors: Tang Linsheng , Yang Jingwei , Yin Yanbai , Zhang Mei
Published: November 2005

The stability of emulsifier‐minor emulsion polymerization and the final latices depends on whether water‐soluble monomers can be bound to the particle after polymerization, which relies on the hydrophilicity of the water‐soluble monomers. Less hydrophilic monomers are apt to be buried in the latex particle, but extremely hydrophilic monomers tend to homopolymerize in the water phase. The suitable hydrophilic index I/O of water‐soluble monomers is preferably 3–5. The adhesion power and water resistance of emulsifier‐minor latex films are better than that of conventional latex film, but the impact resistance and gloss of the former are poorer. The gloss and water resistance of the emulsifier‐minor latex films are relevant to the type of water‐soluble monomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 796–801, 2006
Superstructure and mechanical properties of nylon 66 microfiber prepared by carbon dioxide laser‐thinning method
Authors: Suzuki Akihiro , Hasegawa Toshinori
Published: November 2005

Nylon 66 microfibers were obtained by a carbon dioxide (CO2) laser‐thinning method. A laser‐thinning apparatus used to continuously prepare microfibers consisted of spools supplying and winding the fibers, a continuous‐wave CO2‐laser emitter, a system supplying the fibers, and a traverse. The diameter of the microfibers decreased as the winding speed increased, and the birefringence increased as the winding speed increased. When microfibers, obtained through the laser irradiation (at a power density of 8.0 W cm−2) of the original fiber supplied at 0.23 m min−1, were wound at 2000 m min−1, they had a diameter of 2.8 μm and a birefringence of 46 × 10−3. The draw ratio calculated from the supplying and winding speeds was 8696×. Scanning electron microscopy showed that the microfibers obtained with the laser‐thinning apparatus had smooth surfaces not roughened by laser ablation that were uniform in diameter. To study the conformational transition with winding speed, the changes in trans band at 936 cm−1 and gauche band at 1136 cm−1 were measured with a Fourier transform infrared microscope. The trans band increased as the winding speed increased, and the gauche band decreased. Young's modulus and tensile strength increased with increasing winding speed. The microfiber, which was obtained at a winding speed of 2000 m min−1, had a Young's modulus of 2.5 GPa and tensile strength of 0.6 GPa. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 802–807, 2006
Influence of polymer–filler interactions on retraction behaviors of natural rubber vulcanizates reinforced with silica and carbon black
Authors: Choi Sung‐Seen
Published: November 2005

In general, silica‐filled rubber compounds contain a silane coupling agent to improve the filler dispersion and polymer–filler interactions. The silane coupling agent modifies the silica surface and makes crosslinks between the rubber and the silica. Influence of the modification of silica on the retraction behaviors of natural rubber (NR) vulcanizates reinforced with silica and carbon black was studied. Variation of the retraction behaviors of NR vulcanizates with filler composition was also investigated. The vulcanizates containing the silane coupling agent were recovered faster than those without the silane coupling agent. The recovery difference between the vulcanizates without and with the silane coupling agent increased with increased silica content. For the vulcanizates containing the silane coupling agent, the retraction behaviors were nearly the same, irrespective of filler composition. But, for the vulcanizates without the silane coupling agent, the vulcanizate was recovered more and more slowly as the silica content increased. The experimental results are explained with the polymer–filler interactions, modification of silica surface, and formation of crosslinks between silica and rubber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 691–696, 2006
Metal ion retention properties of water‐insoluble polymers containing carboxylic acid groups
Authors: Rivas Bernabé L. , Quilodrán Benita , Quiroz Eduardo
Published: November 2005

Crosslinked poly(acrylic acid), PAA, and poly(2‐acrylamidoglycolic acid), PAAG, were synthesized by radical polymerization. Both resins contain carboxylic acid groups. PAA at basic pH exists basically as an acrylate anion and PAAG shows three atoms or groups, carboxylic acid, hydroxyl, and amide groups, that can act as ion exchanger or chelating groups. Both resins are studied as adsorbents to trace metal ions from saline aqueous solutions and natural sea water and their properties by Batch equilibrium procedure are compared. The metal ions studied under competitive and noncompetitive conditions were Cu(II), Pb(II), Cd(II), and Ni(II). The effects of pH, time of contact, amount of resin, temperature, and salinity were studied. Resin PAA shows a high affinity (>80%) for Cu(II) and Cd(II) and resin PAAG shows also a high affinity for Ni(II), Pb(II), and Cd(II). By treatment of the metal ion‐loaded resin with 4M HNO3 it is possible to recover completely the Cu(II) ions from resin PAA and Ni(II) and Pb(II) from resin PAAG. The metal ion retention properties were studied with natural sea water. For those natural sea waters containing Cu(II) and Cd(II), the resins showed a high affinity for Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 697–705, 2006
Thermooxidative degradation of isotactic polypropylene prepared on metallocene catalyst and its sorption capacity
Authors: Mohakhova T. V. , Nedorezova P. M. , Shlyapnikov Yu. A.
Published: November 2005

The sorption capacity and resistance to thermooxidative degradation are comparatively studied for isotactic polypropylene (PP) produced in the medium of the liquid monomer on homogeneous metallocene catalytic systems and on a heterogeneous titanium–magnesium catalyst. These polymers are characterized by different sorption capacities with respect to the phenyl‐β‐naphthylamine antioxidant and different induction periods of oxidation by molecular oxygen. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 808–811, 2006
Fluorinated acrylic polymers: Surface properties and XPS investigations
Authors: Saïdi Salima , Guittard Frédéric , Guimon Claude , Géribaldi Serge
Published: November 2005

A series of polymers based on methylmethacrylate, butylacrylate, and ω‐perfluorooctylalkylacrylate were prepared by radical polymerization. By changing both the length of the hydrocarbon spacer, between the fluorinated chain and the ester function of the fluorinated monomer, and its concentration, the surface properties of the resulting terpolymers were greatly influenced. Polymers containing small amounts of fluorinated comonomer units had considerably reduced surface energies compared to the copolymer poly (methylmethacrylate‐co‐butylacrylate) taken as reference. The outermost surface composition has been investigated by the XPS technique, confirming the strong fluorine enrichment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 821–827, 2006
Releasing polyacrylonitrile from poor biodegradability by insertion of a highly biodegradable chemical structure into the main chain
Authors: Kawabata Nariyoshi , Ohashi Kenji , Nishiyama Takeshi
Published: November 2005

Polyacrylonitrile turned biodegradable by incorporation of N‐benzyl‐4‐vinylpyridinium chloride (BVP), a highly biodegradable chemical structure, into the main chain. Oligomers of acrylonitrile are biodegradable dissimilar to polyacrylonitrile, and connection of them by BVP produced biodegradable polymers. The half‐life of a copolymer of acrylonitrile with BVP (PAN‐co‐BVP) in a molar ratio of 97 : 3 was 21 days when treated with activated sludge in soil. The average number of acrylonitrile units in the oligo‐acrylonitrile portion was 32. Degradation at the BVP portion appeared predominant, but the oligo‐acrylonitrile portion also underwent exhaustive degradation when the portion was sufficiently short. Even though biodegradable, oligo‐acrylonitriles are not useful as polymeric materials, but connection of them by BVP produces useful polymeric materials possessed of sufficient biodegradability. Such bridged polymer is different from conventional polyacrylonitrile, and its utility may be different to some extent, but it possesses sufficient biodegradability. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 852–857, 2006
Preparation and properties of polyimide nanocomposites via a soluble polyisoimide precursor
Authors: Oh Seung Bae , Kim Young Jun , Kim Ji Heung
Published: November 2005

A polyisoimide based on 4,4′‐oxydiphthalic dianhydride and 4,4′‐oxydianiline was synthesized and used for the preparation of nanocomposites with commercial organoclays by the solution dispersion technique. The cast composite films were heat‐treated to convert them into polyimide nanohybrid films. Homogeneous dispersions were obtained at lower clay concentrations (<5 wt %), and this was confirmed by X‐ray diffraction and transmission electron microscopy. The nanocomposites displayed improved thermal and mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 869–874, 2006
Morphology and mechanical properties of blends of thermoplastic polyurethane and polyolefins
Authors: Di Yali , Kang Maoqing , Zhao Yuhua , Yan Shirun , Wang Xinkui
Published: November 2005

Polyolefins (PO) were melt mixed with thermoplastic polyurethane (TPU) in a 20 : 80 weight ratio with or without compatibilizer containing 0.5 wt % of maleic anhydride. Effects of component viscosities on morphology and on mechanical properties of the blend were studied by scanning electron microscope (SEM), tensile property analysis, and dynamic mechanical analysis (DMA). It was found that the disperse particle size of compatibilizer‐free blends decreased with the decreasing viscosity ratio of the disperse phase to TPU. The efficiency of the compatibilizer in reducing the particle size varied with viscosity ratios of the disperse phase to compatibilizer. However, the particle size did not decrease with the decreasing viscosity ratio monotonically. With lower viscosity ratio, addition of 5 wt % compatibilizer resulted in a greater reduction of particle size and less loss in the tensile properties as compared to the TPU matrix. For the polyethene (PE) that has the lowest viscosity value among all the POs, its size in the blend was stabilized with the addition of compatibilizer and no compatibilization was detected by DMA and by tensile property analysis. The mobility of the disperse phase and compatibilizer and the dispersion competition between them seemed important. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 875–883, 2006
New Agents with Antimycobacterial Activity
Authors: Marco‐Contelles José , Gómez‐Sánchez Elena
Published: November 2005

In this paper, we report that a series of structurally simple a‐halogenoacetamides (1–8) show potent and excellent antimycobacterial activities against drug‐sensitive Mycobacterium tuberculosis H37Rv and drug‐resistant M. avium.
Synthesis of 5,6‐Dimethyl‐9‐methoxy‐1‐phenyl‐6H‐pyrido[4,3‐b]carbazole Derivatives and their Cytotoxic Activity
Authors: Jasztold‐Howorko Ryszard , Pelczynska Marzena , Nasulewicz Anna , Wietrzyk Joanna , Opolski Adam
Published: November 2005

Starting from 2‐(6‐methoxy‐1‐methyl‐9H‐carbazol‐2‐yl)ethylamine 7 and mixed anhydrides of 4‐nitrobenzoic acid or 4‐methoxybenzoic acid, the corresponding 5,6‐dimethyl‐9‐methoxy‐1‐(4‐substituted phenyl)‐6H‐pyrido[4,3‐b]carbazoles 11a–b, 5,6‐dimethyl‐9‐hydroxy‐1‐(4‐substituted phenyl)‐6H‐pyrido[4,3‐b]carbazoles 12a, 12c, and their quaternary salts 13a–d were obtained. The four new pyridocarbazole derivatives 12a–c and 13d satisfy the international activity criterion for synthetic compounds, namely an ID50 value lower then 4 μg/mL in preliminary in vitro cytotoxic activity screening against the A549 cell line (non‐small cell lung cancer).
Stereoisomers of Compounds with Symmetric Constitutions
Authors: Siebert Carsten D. , Tampe Niels
Published: November 2005

Chiral organic compounds with unsymmetric constitutions can lead to Nr = 2n stereoisomers. By contrast, if a chiral compound has a symmetric constitution, then the number of stereoisomers is reduced [1]. In this publication, we wish to present an algorithm to calculate the number of stereoisomers of chiral organic compounds of the latter type (e. g. sugar acids). The first step is the development of two different functions for unbranched compounds where the number of repeating units is even or uneven. Other stereogenic units like double bonds, chiral axes or planes are not discussed. The results are then checked against the actual isomers. The next step leads to a unified equation to predict the precise number of stereoisomers that can exist. Thus, the relationship between chirality and symmetry is shown in detail. Additionally, the algorithm is applied to some drug molecules with symmetric constitutions.
Synthesis and Antiplatelet Activity of New Imidazole‐4‐Carboxylic Acid Derivatives
Authors: Rehse Klaus , Steege Jens
Published: November 2005

1‐Arylalkyl‐5‐phenylsulfonamino‐imidazole‐4‐carboxylic acid esters and their carboxamides with an additional secondary amino group were synthesized and identified as antiplatelet agents in a low micromolar range (Born‐test, inducer collagen). To describe the mechanism of action more precisely the Born‐test was carried out as well with ADP, adrenaline or PAF, respectively. In addition, two compounds were investigated for their COX‐1 inhibitory activities. Provided the essential structural criteria are met i.e. amide group or ester, sulfonylamino rest, hydrophobic moieties, and a secondary amino function, slight structural modifications are able to shift the pattern of activity among the above platelet receptors. So, the ester 5c exhibits PAF antagonistic activity at IC50 = 1 μM and COX‐1 inhibition (IC50 = 0.4 μM). The carboxamide 6c shows ADP antagonistic properties (IC50 = 2 μM). Compound 6g is as well PAF antagonistic (IC50 = 4 μM) and a COX‐1 inhibitor (IC50 = 1 μM). The derivative 6i shows a strong antiadrenergic (IC50 = 0.15 μM) and PAF antagonistic (IC50 = 0.66 μM) effect.
New Pyrimido[5,4‐c]cinnolines with Antiplatelet Activities
Authors: Rehse Klaus , Gonska Hedwig
Published: November 2005

Twenty one new pyrimido[5,4‐c]cinnolines containing different lipophilic moieties (viz. phenyl, 4‐methoxyphenyl, 2‐furanyl, 2‐thienyl) in position 2 and additional basic groups (e.g., alkylaminopropyl, dialkylaminopropyl and cyclohexylaminopropyl) in position 4 of the title ring system have been prepared and investigated for antiplatelet effects (Born test). Ten of them inhibited the platelet aggregation induced by collagen with an IC50 below 10 μmol/L (6a, 6b, 6c, 6g, 6h, 6i, 6k, 6m, 6q, 6u). A closer inspection of the antiplatelet effect with other inducers showed antagonism against adrenaline (6m), ADP antagonist (6i) and PAF antagonist activities (6m, 6i, 6u) in nanomolar (IC50) concentration ranges.
Synthesis and Anti‐HCMV Activity of Novel 5′‐Norcarboacyclic Nucleosides
Authors: Kim Aihong , Hong Joon Hee
Published: November 2005

A very simple route for synthesizing a novel carboacyclic version of 5¢‐noraristeromycin is described. Condensation of the mesylates 9 and 23 with the natural nucleosidic bases (A, U, T, C) under standard nucleophilic substitution (K2CO3, 18‐Crown‐6, DMF) and deblocking conditions, afforded the target nucleosides 14, 15, 16, 17, 28, 29, 30, and 31. In addition, these compounds were evaluated for their antiviral properties against various viruses.
Word sense disambiguation by selecting the best semantic type based on Journal Descriptor Indexing: Preliminary experiment
Authors: Humphrey Susanne M. , Rogers Willie J. , Kilicoglu Halil , Demner‐Fushman Dina , Rindflesch Thomas C.
Published: November 2005

An experiment was performed at the National Library of Medicine® (NLM®) in word sense disambiguation (WSD) using the Journal Descriptor Indexing (JDI) methodology. The motivation is the need to solve the ambiguity problem confronting NLM's MetaMap system, which maps free text to terms corresponding to concepts in NLM's Unified Medical Language System® (UMLS®) Metathesaurus®. If the text maps to more than one Metathesaurus concept at the same high confidence score, MetaMap has no way of knowing which concept is the correct mapping. We describe the JDI methodology, which is ultimately based on statistical associations between words in a training set of MEDLINE® citations and a small set of journal descriptors (assigned by humans to journals per se) assumed to be inherited by the citations. JDI is the basis for selecting the best meaning that is correlated to UMLS semantic types (STs) assigned to ambiguous concepts in the Metathesaurus. For example, the ambiguity transport has two meanings: “Biological Transport” assigned the ST Cell Function and “Patient transport” assigned the ST Health Care Activity. A JDI‐based methodology can analyze text containing transport and determine which ST receives a higher score for that text, which then returns the associated meaning, presumed to apply to the ambiguity itself. We then present an experiment in which a baseline disambiguation method was compared to four versions of JDI in disambiguating 45 ambiguous strings from NLM's WSD Test Collection. Overall average precision for the highest‐scoring JDI version was 0.7873 compared to 0.2492 for the baseline method, and average precision for individual ambiguities was greater than 0.90 for 23 of them (51%), greater than 0.85 for 24 (53%), and greater than 0.65 for 35 (79%). On the basis of these results, we hope to improve performance of JDI and test its use in applications.
Moderating information and communication technologies' influences on socioeconomic development with good governance: A study of the developing countries
Authors: Meso Peter , Datta Pratim , Mbarika Victor
Published: November 2005

With the increasing globalization of the world economy, there has been a growing interest in the potential contributions of good governance to accelerating the rate of economic and social development in the developing countries, and enhance their smooth integration into the emerging global economy. Simultaneously, developed economies are experiencing an increasing proportion in the contribution of knowledge, information, and telecommunication sectors to their overall gross domestic product. This is placing increased focus on the role and contribution of national information infrastructure to economic productivity, and in extension, to the economic and social development of nations. In this article, the authors explore the link between information and communication technologies (ICTs), governance, and social economic development in the developing countries. They empirically conclude that contributions of ICTs to social–economic development are influenced by sociopolitical governance—leading to national development through more prudent and egalitarian application and use of the ICTs' portfolio. The contingent role of governance on ICTs and national development paves the path towards recognizing the importance of sociopolitical moderators.
Identifying a better measure of relatedness for mapping science
Authors: Klavans Richard , Boyack Kevin W.
Published: November 2005

Measuring the relatedness between bibliometric units (journals, documents, authors, or words) is a central task in bibliometric analysis. Relatedness measures are used for many different tasks, among them the generating of maps, or visual pictures, showing the relationship between all items from these data. Despite the importance of these tasks, there has been little written on how to quantitatively evaluate the accuracy of relatedness measures or the resulting maps. The authors propose a new framework for assessing the performance of relatedness measures and visualization algorithms that contains four factors: accuracy, coverage, scalability, and robustness. This method was applied to 10 measures of journal–journal relatedness to determine the best measure. The 10 relatedness measures were then used as inputs to a visualization algorithm to create an additional 10 measures of journal–journal relatedness based on the distances between pairs of journals in two‐dimensional space. This second step determines robustness (i.e., which measure remains best after dimension reduction). Results show that, for low coverage (under 50%), the Pearson correlation is the most accurate raw relatedness measure. However, the best overall measure, both at high coverage, and after dimension reduction, is the cosine index or a modified cosine index. Results also showed that the visualization algorithm increased local accuracy for most measures. Possible reasons for this counterintuitive finding are discussed.
Tragwerke aus Textilbeton – Berechnungsmodelle, Anwendungen
Authors: Möller Bernd , Graf Wolfgang , Hoffmann Andreas , Sickert Jan‐Uwe , Steinigen Frank
Published: November 2005

Tragwerke mit Bewehrung aus textilen Gelegen sind eine innovative Entwicklung im Bauwesen. Die in Feinbeton eingebettete textile Bewehrung kann für Neubauteile und nachträgliche Verstärkungen verwendet werden. Für Tragwerke aus Textilbeton werden im Beitrag Berechnungsmodelle und Anwendungsbeispiele vorgestellt, die im Sonderforschungsbereich 528 entstanden. Ein besonderer Akzent wird durch die verallgemeinerte Behandlung unscharfer Daten gesetzt, da Datenunschärfe signifikanten Einfluß auf die Systemantworten hat.
Tragfähigkeitsuntersuchungen der Natursteinmauerwerkstützen des Berliner Olympiastadions
Authors: Schlegel Roger , Rautenstrauch Karl , Auberg Rainer
Published: November 2005

Bei der Modernisierung bzw. Instandsetzung baulicher Anlagen stellt sich häufig die Frage nach der tatsächlichen Tragfähigkeit der bestehenden Bauteile und dem damit im Zusammenhang stehenden Umfang erforderlicher Verstärkungs‐ und Sanierungsmaßnahmen. Für eine sinnvolle und wirtschaftliche Planung kann daher die Qualität und die Realitätsnähe der Bestimmung von Tragfähigkeit und Gebrauchstauglichkeit eine große Bedeutung erlangen. Der Einsatz herkömmlicher, einfacher Ingenieurmodelle stößt dabei mit zunehmender Komplexität der Struktur sehr schnell an Grenzen und kann zu unwirtschaftlichen Ergebnissen führen.

Der vorliegende Beitrag zeigt am Beispiel der Natursteinmauerwerkstützen des Berliner Olympiastadions einen Weg, die Tragfähigkeit einer bestehenden Mauerwerkstruktur durch die Kombination von gezielter Zustandsaufnahme sowie Materialprüfung mit modernen, vorwiegend zerstörungsfreien Prüfmethoden und dem Einsatz eines darauf abgestimmten, leistungsfähigen und wirklichkeitsnahen Berechnungsmodells zuverlässig bestimmen zu können. Dabei zeigt sich, daß die realitätsnahe rechnerische Bewertung der Versagenslast und der zugehörigen Versagensmechanismen die Einbeziehung des nichtlinearen Spannungs‐Verformungsverhaltens des Mauerwerks erforderlich macht. Das nichtlineare Materialverhalten wurde mit einem in das Finite‐Element‐Programm ANSYS® implementierten elastoplastischen 3D‐Materialmodell für Mauerwerk erfaßt. Damit wurde es möglich, den Spannungs‐ und Verformungszustand der Mauerwerkstruktur sehr realitätsnah abzubilden und die Standsicherheit sowie die Gebrauchstauglichkeit der Stützenstruktur unter Einbeziehung der Lastgeschichte plausibel nachzuweisen.
In vitroinhibitory effects of non‐steroidal anti‐inflammatory drugs on 4‐methylumbelliferone glucuronidation in recombinant human UDP‐glucuronosyltransferase 1A9—potent inhibition by niflumic acid
Authors: Mano Yuji , Usui Takashi , Kamimura Hidetaka
Published: November 2005

The inhibitory potencies of non‐steroidal anti‐inflammatory drugs (NSAIDs) on UDP‐glucuronosyltransferase (UGT) 1A9 activity were investigated in recombinant human UGT1A9 using 4‐methylumbelliferone (4‐MU) as a substrate for glucuronidation. 4‐MU glucuronidation (4‐MUG) showed Michaelis‐Menten kinetics with aKmvalue of 6.7 µM. The inhibitory effects of the following seven NSAIDs were investigated: acetaminophen, diclofenac, diflunisal, indomethacin, ketoprofen, naproxen and niflumic acid. Niflumic acid had the most potent inhibitory effect on 4‐MUG with an IC50value of 0.0341 µM. The IC50values of diflunisal, diclofenac and indomethacin were 1.31, 24.2, and 34.1 µM, respectively, while acetaminophen, ketoprofen and naproxen showed less potent inhibition. Niflumic acid, diflunisal, diclofenac and indomethacin inhibited 4‐MUG competitively withKivalues of 0.0275, 0.710, 53.3 and 69.9 µM, respectively, being similar to each IC50value. In conclusion, of the seven NSAIDs investigated, niflumic acid was the most potent inhibitor of recombinant UGT1A9 via 4‐MUG in a competitive manner. Copyright © 2005 John Wiley & Sons, Ltd.
The effect of increased lipoprotein levels on the pharmacokinetics of cyclosporine A in the laboratory rat
Authors: Brocks Dion R. , Ala Shahram , Aliabadi Hamidreza Montazeri
Published: November 2005

The response of cyclosporine A (CyA) blood concentrations following changes in lipoprotein levels have been inconsistent. Some studies show increases in concentrations, whereas others have shown decreases. The intent of this study was to examine the effect of two rat models of increased lipoprotein on the pharmacokinetics of CyA. One was a simulated high fat content meal, in which 1% cholesterol in peanut oil was administered. The other was the poloxamer 407‐induced model of hyperlipidemia. Rats in these two groups were compared to a group fasted overnight before the study. In rats given a simulated high fat meal, at most time points the mean blood and plasma concentrations were lower, though not significantly, compared to fasted animals. Oral lipid led to no significant changes in the measured pharmacokinetic parameters of blood or plasma area under the concentration vs time curve (AUC), clearance (CL), volume of distribution (Vd) or plasma unbound fraction. In the poloxamer 407‐treated hyperlipidemic rats there were significant reductions in plasma unbound fraction plasma,Vdand terminal half‐life, but notAUCorCL, compared to normolipidemic rats. In contrast, theCL,Vdandt1/2in the oral lipid‐fed rats were all significantly higher than the poloxamer 407 treated animals. Oral absolute bioavailability of CyA was unchanged by oral lipid. In humans and rats the pharmacokinetics of CyA in the face of increased lipoprotein levels do not correspond well to what is typically seen for other drugs that are known to bind to lipoproteins. Copyright © 2005 John Wiley & Sons, Ltd.
Intestinal absorption characteristics of ketoprofen in rats
Authors: Choi Jun‐Shik , Jin Ming Ji , Han Hyo‐Kyung
Published: November 2005

The present study aims to investigate the intestinal absorption characteristics of ketoprofen in rats. The pharmacokinetic profile of ketoprofen was evaluated following a single p.o. administration of ketoprofen (1 mg/kg) to rats in the absence and presence of benzoic acid or lactic acid (2 and 10 mg/kg), the substrates of monocarboxylic acid transporters. The pharmacokinetic profiles of ketoprofen (1 mg/kg) were significantly altered by the concurrent use of benzoic acid or lactic acid (10 mg/kg), compared with the control (given ketoprofen alone). TheCmaxandAUCof ketoprofen in the presence of benzoic acid or lactic acid (10 mg/kg) were significantly (p<0.05) lower than those from the control group, while there was no significant change inTmaxand the terminal plasma half‐life (T1/2) of ketoprofen. These results suggest that ketoprofen shares a common transport pathway with benzoic acid and lactic acid during the intestinal absorption in rats. Copyright © 2005 John Wiley & Sons, Ltd.
Conformation of alloHyp in the Y position in the host–guest peptide with the pro–pro–gly sequence: Implication of the destabilization of (Pro–alloHyp–Gly)10
Authors: Jiravanichanun Nattha , Nishino Norikazu , Okuyama Kenji
Published: November 2005

The crystal structure of the host–guest peptide, (Pro–Pro–Gly)4–(Pro–alloHyp–Gly)–(Pro–Pro–Gly)4, was analyzed at high resolution. allohydroxyproline (alloHyp), 4S‐hydroxyproline, was successfully characterized through the use of a host–guest peptide, while the previous study indicated the inability of a triple helical formation of (Pro–alloHyp–Gly)10. A detailed analysis of alloHyp conformation in collagen‐like models sheds light on the role played by its puckering in the triple‐helix stabilization and destabilization. That is, the alloHyp typically adopts down puckering. However, it adopted up puckering in the Y position in the Pro–alloHyp–Gly guest triplet, which was not preferable conformation for alloHyp. Therefore, the energetically unfavorable conformations seemed to play the key role in giving destabilization to the triple helix in (Pro–alloHyp–Gly)10. The intrinsic hydration pattern in (Pro–Pro–Gly)9 was conserved even in the surrounding alloHyp residues. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 225–233, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Thermal stabilization of human albumin by medium‐ and short‐chain n‐alkyl fatty acid anions
Authors: Shrake Andrew , Frazier Douglas , Schwarz Frederick P.
Published: November 2005

A comprehensive study of the thermal stabilization of defatted human albumin monomer by n‐alkyl fatty acid anions (FAAs), formate through n‐decanoate, was carried out by differential scanning calorimetry (DSC). The concentration of each ligand affording maximum thermal stabilization was determined; n‐nonanoate provides the greatest stabilization but is only marginally better than n‐octanoate and n‐decanoate. The use of reversible thermodynamics and a two‐state denaturation model for albumin has been validated. Standard free energies of binding, calculated from increases in free energy of denaturation, for n‐butanoate and longer FAAs, are linear with n‐alkyl chain length whereas those for formate, acetate, and n‐propionate deviate from linearity; those for acetate and n‐propionate are even greater than that of n‐butanoate, thereby suggesting, in addition to the common class of sites available to all such ligands, the presence of an additional class of lower affinity binding sites available only to these shortest ligands. Competition experiments involving acetate and n‐octanoate and involving n‐pentanoate and n‐octanoate confirmed the binding of acetate to lower affinity sites unavailable to n‐octanoate and n‐pentanoate. Furthermore, an equation is provided, allowing computation of the transition temperature as a function of the free energy for any reversible process causing a change in thermal stability of a protein undergoing reversible, two‐state denaturation. With this equation, modeling the competition experiments by using the binding parameters determined by DSC provides additional support for the class of lower affinity sites, which play a significant role in thermal stabilization of albumin at higher concentrations of these shortest FAAs. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 235–248, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
One‐ and two‐photon induced fluorescence of Pacific Blue‐labeled human serum albumin deposited on different core size silver colloids
Authors: Lukomska Joanna , Gryczynski Ignacy , Malicka Joanna , Makowiec Slawomir , Lakowicz Joseph R. , Gryczynski Zygmunt
Published: November 2005

We studied one‐ and two‐photon induced fluorescence of Pacific Blue (PB)‐labeled human serum albumin (HSA) in the presence of different size silver colloids. The PB fluorescence emission intensity was observed with small (30–40 nm) and large (about 120 nm) colloids and compared with PB emission in absence of colloids. For the system with a small core size colloids we did not detect any fluorescence enhancement with one‐photon excitation and the enhancement observed with two‐photon excitation was about 2.5‐fold. In contrast, for large silver colloids we observed about a 2‐fold increase in PB fluorescence brightness for one‐photon excitation, and the enhancement with two‐photon excitation excided 13‐folds. Much stronger increases in brightness observed with two‐photon excitation, compared to one‐photon excitation, indicate a dominant role of enhanced local field in fluorescence enhancement on silver colloids in solutions. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 249–255, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com