bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and dielectric properties of polystyrene‐clay nanocomposite materials
Authors: Wang Hong‐Wen , Chang Kung‐Chin , Yeh Jui‐Ming , Liou Shir‐Joe 
Published: November 2003

AbstractPolystyrene‐clay nanocomposite (PsCN) materials were synthesized and their properties of crystallinity, thermal behavior, and dielectric characteristics were investigated. A polymerizable cationic surfactant, [2‐(dimethylamino)ethyl]triphenylphonium bromide, was used for the intercalation of montmorillonite (MMT). The organophilic MMT was prepared by Na+‐exchanged MMT and ammonium cations of a cationic surfactant in an aqueous medium. Organophilic styrene monomers were intercalated into the interlayer regions of organophilic clay hosts followed by a free‐radical polymerization. Exfoliation to 2 wt % MMT in the polystyrene (PS) matrix was achieved as revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were also studied. The dielectric properties of PsCNs in the form of film with clay loading from 1.0 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 25–70°C. A decreased dielectric constant and low dielectric loss were observed for PsCN materials. The dielectric response at low frequency that originated from dipole orientation was suppressed due to the intercalation of clay materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1368–1373, 2004
Binding and reversible denaturation of double‐stranded DNA by Ff gene 5 protein
Authors: Mou Tung‐Chung , Shen Michelle C. , Terwilliger Thomas C. , Gray Donald M. 
Published: November 2003

AbstractThe gene 5 protein (g5p) from Ff filamentous virus is a model single‐stranded DNA (ssDNA) binding protein that has an oligonucleotide/oligosaccharide binding (OB)‐fold structure and binding properties in common with other ssDNA‐binding proteins. In the present work, we use circular dichroism (CD) spectroscopy to analyze the effects of amino acid substitutions on the binding of g5p to double‐stranded DNA (dsDNA) compared to its binding to ssDNA. CD titrations of poly[d(A) · d(T)] with mutants of each of the five tyrosines of the g5p showed that the 229‐nm CD band of Tyr34, a tyrosine at the interface of adjacent protein dimers, is reversed in sign upon binding to the dsDNA, poly[d(A) · d(T)]. This effect is like that previously found for g5p binding to ssDNAs, suggesting there are similarities in the protein–protein interactions when g5p binds to dsDNA and ssDNA. However, there are differences, and the possible perturbation of a second tyrosine, Tyr41, in the complex with dsDNA. Three mutant proteins (Y26F, Y34F, and Y41H) reduced the melting temperature of poly[d(A) · d(T)] by 67°C, but the wild‐type g5p only reduced it by 2°C. This enhanced ability of the mutants to denature dsDNA suggests that their binding affinities to dsDNA are reduced more than are their binding affinities to ssDNA. Finally, we present evidence that when poly[d(A) · d(T)] is melted in the presence of the wild‐type, Y26F, or Y34F proteins, the poly[d(A)] and poly[d(T)] strands are separately sequestered such that renaturation of the duplex is facilitated in 2 mM Na+. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70: 637–648, 2003
Tryptophanyl substitutions in apomyoglobin affect conformation and dynamic properties of AGH subdomain
Authors: Sirangelo Ivana , Iannuzzi Clara , Malmo Clorinda , Irace Gaetano 
Published: November 2003

AbstractThe solvent accessibilities to the tryptophanyl microenvironments of wild type sperm whale apomyoglobin (apoMb) and two mutants (W7F and W14F) containing a single tryptophan are measured by fluorescence quenching studies. The results are compared to those relative to horse apoMb. In the wild type sperm whale protein, no difference is noticed in the solvent accessibility of the two indole residues, as documented by the values of the Stern–Volmer constants. By contrast, the two tryptophan residues of horse apoMb are exposed to the solvent in a different way, thus indicating that some local conformational differences exist between the two homologous proteins in solution. The single W → F substitution at either position 7 or 14 determines local conformational changes that increase the accessibility of the remaining indole residue but do not affect the overall architecture of the protein molecule. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70:649–654, 2003
Effects of metallic silver island films on resonance energy transfer between N,N′‐(dipropyl)‐tetramethyl‐ indocarbocyanine (Cy3)‐ and N,N′‐(dipropyl)‐tetramethyl‐ indodicarbocyanine (Cy5)‐labeled DNA
Authors: Malicka Joanna , Gryczynski Ignacy , Kusba Jozef , Lakowicz Joseph R. 
Published: November 2003

AbstractResonance energy transfer (RET) is typically limited to distances below 60 Å, which can be too short for some biomedical assays. We examined a new method for increasing the RET distances by placing donor‐ and acceptor‐labeled DNA oligomers between two slides coated with metallic silver particles. A N,N′‐(dipropyl)‐tetramethylindocarbocyanine donor and a N,N′‐(dipropyl)‐tetramethylindodicarbocyanine acceptor were covalently bound to opposite 5′ ends of complementary 23 base pair DNA oligomers. The transfer efficiency was 25% in the absence of silver particles or if only one slide was silvered, and it increased to an average value near 64% between two silvered slides. The average value of the Forster distance increased from 58 to 77 Å. The energy transfer data were analyzed with a model assuming two populations of donor–acceptor pairs: unaffected and affected by silver island films. In an affected fraction of about 28%, the apparent energy transfer efficiency is near 87% and the Forster distance increases to 119 Å. These results suggest the use of metallic silver particles to increase the distances over which RET occurs in biomedical and biotechnology assays. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70: 595–603, 2003
Effects of aluminum sorption on calcium‐polygalacturonate network used as soil–root interface model
Authors: Mimmo T. , Marzadori C. , Francioso O. , Deiana S. , Gessa C. E. 
Published: November 2003

AbstractThe objective of this study is to determine the influence of aluminum sorption on a calcium–polygalacturonate (Ca‐PG) network used as a soil–root interface model. The Ca‐PG network is exposed to aluminum solutions at different concentrations (25–800 μM) at pH 3.50. High concentrations lead to a release of calcium (80%) and aluminum becomes the predominant reticulating cation of the polygalacturonic chains. The FTIR spectra show how aluminum sorption induces shifts of the characteristic bands of carbohydrates in the spectral regions of 1700–1400 and 1200–800 cm−1, which are enhanced by decreasing intensities. This might be induced by a weakening of the metal–PG complex through conformational variations of the structure. Scanning electron micrographs also show a collapse of the fibrillar structure of Ca‐PG that is due to aluminum sorption. This structural rearrangement suggests that the soil–root interface could modify its functionality, affecting the transport of metal ions (nutrients) across the interface and consequently through the cell membranes. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70: 655–661, 2003
Cervical cancer control, priorities and new directions
Authors: Monsonego Joseph , Bosch F. Xavier , Coursaget Pierre , Cox John Thomas , Franco Eduardo , Frazer Ian , Sankaranarayanan Rengaswamy , Schiller John , Singer Albert , Wright Tom , Kinney Walter , Meijer Chris , Linder James 
Published: November 2003

AbstractCervical cancer is caused by infection with a range of high risk “oncogenic” human papillomavirus (HPV) types, and it is now accepted that >99% of cervical cancer is initiated by HPV infection. The estimated lifetime risk of cervical cancer is nevertheless relatively low (less than 1 in 20 for most community based studies). Although sensitivity and specificity of the available diagnostic techniques are suboptimal, screening for persistent HPV infection is effective in reducing the incidence of cervical cancer. Infection can be detected by molecular techniques or by cytological examination of exfoliated cervical cells. Persistent infection is the single best predictor of risk of cervical cancer.1The latest findings of HPV and cervical cancer research need to be widely disseminated to the scientific and medical societies that are updating screening and management protocols, public health professionals, and to women and clinicians. This report reviews current evidence, clinical implications and directions for further research in the prevention, control and management of cervical cancer. We report the conclusions of the Experts' Meeting at the EUROGIN 2003 conference. © 2003 Wiley‐Liss, Inc.
Identification of candidate antigens for serologic detection of Helicobacter pylori‐infected patients with gastric carcinoma
Authors: Krah Alexander , Miehlke Stephan , Pleissner Klaus‐Peter , Zimny‐Arndt Ursula , Kirsch Christian , Lehn Norbert , Meyer Thomas F. , Jungblut Peter R. , Aebischer Toni 
Published: November 2003

AbstractHelicobacter pylori colonizes the stomach of almost half the world population and is a causative agent of gastric carcinomas and duodenal ulcers. Only a small fraction of infected people will develop these severe illnesses and a predictive test to identify people at high risk would greatly benefit disease management. Our study aimed to identify conserved bacterial antigens that may be useful for the development of such a diagnostic test. High‐resolution immunoproteomics by 2‐dimensional electrophoresis of H. pylori 26695 proteins was carried out with sera from infected patients with either duodenal ulcer (n=30) or gastric carcinoma (n=30), 2 clinically divergent conditions. According to their antigen recognition patterns clear groups of patients were identified. Although this classification did not correspond to the clinical status, it may be correlated to other bacterial or host factors that influence the outcome of infection. In general antigen recognition patterns were found to be highly variable, however by utilizing powerful image analysis and statistical tests the recognition of 14 antigenic protein species was found to differ significantly (p<0.01) between both diseases. Particular protein species of GroEL, HyuA, GroES and AtpA appear to be useful surrogate markers for gastric carcinoma detection and consequently should be considered for further prospective studies to assess their predictive value. For one protein species of AtpA, evidence was found that different post‐translational modifications may confer different immunogenicities. © 2003 Wiley‐Liss, Inc.
PGE2‐mediated upregulation of iNOS in murine breast cancer cells through the activation of EP4 receptors
Authors: Timoshenko Alexander V. , Lala Peeyush K. , Chakraborty Chandan 
Published: November 2003

AbstractWe report here that endogenous prostaglandin E2 (PGE2) resulting from cyclooxygenase (COX)‐2 expression in a highly metastatic murine breast cancer cell line C3L5 upregulates IFN‐γ + LPS‐induced nitric oxide (NO) synthase (iNOS) expression and NO production. This action of PGE2 is mediated through the EP4 receptor in a cAMP‐dependent manner. Both nonselective and selective COX‐2 inhibitors suppressed IFN‐γ + LPS‐induced NO production, which was largely restored by exogenous PGE2 or EP4 receptor agonist PGE1 alcohol. EP4 antagonist AH‐23848B inhibited NO production with a concomitant downregulation of iNOS mRNA in IFN‐γ + LPS‐stimulated cells. cAMP dependence of NO production by cells under inducible conditions was demonstrated by the use of known modulators of intracellular cAMP. Since both COX‐2 and iNOS are implicated in breast cancer progression, our findings of EP4 receptor‐mediated upregulation of iNOS in COX‐2‐expressing breast cancer cells suggest that blocking COX‐2 and/or EP4 may provide a simple therapeutic modality in this tumor model. © 2003 Wiley‐Liss, Inc.
Density functional investigation of reaction of borohydride cation BH with propylene
Authors: Qu Zheng‐Wang , Zhu Hui , Li Ze‐Sheng , Zhang Xing‐Kang , Zhang Qi‐Yuan 
Published: November 2003

AbstractThe reactions of BH with propylene (CH2CHCH3) to form both the adducts BC3H and the H2‐elimination products BC3H + H2 have been investigated at the density functional B3LYP/6‐311G(d,p) level of theory. It is shown that the electrophilic attacks of BH towards two olefinic carbons of H2CCHCH3 and two subsequent 1,3‐H‐shifts may form four low‐lying BC3H isomers (with the relative energies in parentheses in kcal/mol): 1 BH · CH2CHCH3 (0.0), 1′ BH · CH3CHCH2 (6.3), 3 BHCH2CH2CH (4.3), and 4 BHCH(CH3) (5.0), respectively. On the other hand, further H2‐eliminations may also occur easily between BC bonds of isomers 1 and 1′ and between CC bonds of isomers 3 and 4 to form two dissociation products (P1) HBCHCHCH + H2 and (P2) HBC(CH3)CH + H2, with H2‐elimination from isomer 1 to be energetically most favorable. According to our calculated mechanism, the collisional stabilization processes of low‐lying isomers 1, 1′, 3, and 4 may compete extensively with their H2‐eliminations processes for the title reaction, leading mainly to some linear carborane cations. This study may be helpful for understanding the stereochemical aspects of borohydride cations towards alkylenes. © 2003 Wiley Periodicals, Inc. J Comput Chem 25: 258–264, 2004
Reorganization of the structures, morphologies, and conformations of polymers by coalescence from their crystalline inclusion compounds formed with cyclodextrins
Authors: Tonelli Alan E. 
Published: November 2003

AbstractWe and several other research groups have recently reported the ability of cyclodextrins (CDs) to act as hosts in the formation of inclusion compounds (ICs) with guest polymers. Polymer‐CD‐ICs are crystalline materials formed by the close packing of host CD stacks, which results in a continuous channel of ∼5‐10Å in diameter running down the interior of the CD stacks. The guest polymers are confined to the narrow, continuous CD channels, and so are necessarily highly extended and segregated from neighboring polymer chains by the walls of the CD stacks. We have shown that coalescence of guest polymers from their CD‐IC crystals can result in a significant reorganization of the structures, morphologies, and even conformations that are normally observed in their bulk samples. For example, when poly(ethylene terephthalate) (PET) is coalesced from its γ‐CD‐IC, we find that in the non‐crystalline regions of the sample the PET chains are adopting highly extended kink conformations, which result in their facile recrystallization from the melt and prevent quenching of the coalesced PET to achieve an amorphous sample during rapid cooling from above Tm. We have also created well‐mixed blends of normally incompatible polymers by coalescing them from CD‐ICs containing both polymers, where they are necessarily spatially proximal. Finally we have found the unique morphologies created by the coalescence of homopolymers, block copolymers, and homopolymer pairs from their CD‐ICs are generally stable to heat treatment for substantial periods above their Tm's and/or Tg's, and so may be thermoplastically processed without loss of the unique morphologies achieved through coalescence from their CD‐IC crystals.
Free energy and dimensions of macromolecules under confinement in layered assemblies
Authors: Cifra Peter , Bleha Tomáš , Škrinárová Zuzana 
Published: November 2003

AbstractThe changes in the free energy ΔA accompanying penetration of polymer solutions from bulk into slit‐like cavities were determined by lattice simulations. In dilute solutions the thermodynamics of penetration is controlled mainly by the parameter ϵw specifying interaction between polymer and walls of repulsive or adsorptive cavities. However, the magnitude of |ΔA| is substantially reduced by increasing concentration ∅︁ in bulk solution. Furthermore, compression of chains by concentration in good solvents and adsorptive cavities was found to be larger in the slit then in the bulk. At intermediate confinement, a region of a minimum coil size was observed at all concentrations and attraction strengths, where molecules are squeezed along all three axes.
Properties of poly(vinyl alcohol)‐graft‐polyacrylamide copolymers depending on the graft length. 1. Redistribution of hydrogen bonds and its influence on the copolymer behavior in aqueous solution
Authors: Zheltonozhskaya Tatyana , Demchenko Olga , Rakovich Irina , Guenet Jean‐Michel , Syromyatnikov Vladimir 
Published: November 2003

AbstractA series of poly(vinyl alcohol)‐graft‐polyacrylamide copolymers (PVA‐g‐PAA) with a constant number N but various molecular weights (lengths) of graft chains, which are intramolecular polymer‐polymer complexes (intraPC), were investigated. The changes in the system of intramolecular hydrogen bonds and state of macromolecules in a solution are considered. The effect of partial detachment of PAA grafts from the main chain caused by the increase in molecular weight of grafts to a more than some critical value (M̄ vPAAcrit≈4.3·105 at N=9) has been revealed. When the length of grafts increases, the thermodynamic quality of water with respect to copolymers improves. The values of z‐average radius of inertia, characteristic viscosity and the number of macromolecules in associate go through a minimum at M̄ vPAA=4.3·105 and then sharply grow with increasing length of grafts.
Dye‐ligand immobilized IPNs membrane for removal heavy metal ions
Authors: Bayramoğlu Gülay , Yalçın Emine , Genç Ömer , Arıca M. Yakup 
Published: November 2003

AbstractWe have developed a novel approach to obtain high metal sorption capacity utilizing a membrane containing chitosan and an immobilized reactive dye (i.e. Reactive Yellow‐2). The composite membrane was characterized by SEM, FT‐IR, swelling test, and elemental analysis. The membrane has uniform small pores distribution and the pore dimensions are between 5 and 10 μm, and the HEMA:chitosan ratio was 50:1. The reactive dye immobilized composite membrane was used in the removal of heavy metal ions [i.e., Pb(II), Hg(II) and Cd(II)] from aqueous medium containing different amounts of these ions (5‐600 mg l−1) and at different pH values (2.0‐7.0). The maximum adsorption capacities of heavy metal ions onto the composite membrane under non‐competitive conditions were 64.3 mmol m−2 for Pb(II), 52.7 mmol m−2 for Hg(II), 39.6 mmol m−2 for Cd(II) and the affinity order was Pb(II) > Hg(II)>Cd(II).
Formation of poly(ethylene glycol) inclusion complexes in aqueous solutions of mixed cyclodextrins
Authors: Horský Jiří , Walterová Zuzana 
Published: November 2003

AbstractEven though the addition of modified cyclodextrins (modified CDs) accelerates the precipitation in aqueous solutions of poly(ethylene glycol) (PEG) and α‐cyclodextrin (α‐CD) the final amount of formed solid complex remains unchanged, with no significant presence of modified CDs detected by MALDI‐TOF mass spectrometry. Thus unsuitability of kinetic turbidity measurements for determination of binding parameters was confirmed. On the other hand, theoretical calculations based on a model of a chain of freely accessible binding sites demonstrated that the results do not necessarily contradict the finding that individual modified CD molecules can thread onto PEG chains with the efficiency comparable to that of natural (unmodified) α‐CD.
Combined‐modality therapy for gastric cancer
Authors: Yao James C. , Mansfield Paul F. , Pisters Peter W.T. , Feig Barry W. , Janjan Nora A. , Crane Christopher , Ajani Jaffer A. 
Published: November 2003

AbstractGastric cancer has a poor prognosis. It is often diagnosed at an advanced stage, and potentially curative treatments often can not be exercised. Even when a curative surgical resection is possible, only a minority of patients survive beyond 5 years, and locoregional failures are frequent among patients undergoing curative resections. Recently, the use of postoperative adjuvant chemoradiotherapy has yielded some notable benefits. Earlier studies have shown survival benefits in patients undergoing chemoradiotherapy for locally advanced unresectable gastric cancer. The recently reported Intergroup 0116 trial compared surgery alone with surgery plus postoperative chemotherapy plus chemoradiotherapy. Superior overall and disease‐free survival rates among patients given combined‐modality postoperative therapy were observed. These results established a new standard of care for patients following resection of gastric carcinoma. Preoperative combined‐modality chemoradiotherapy may improve resectability, and is under investigation at the University of Texas M. D. Anderson Cancer Center. The development of novel radioenhancers and the selection of therapy on the basis of molecular determinants of response may result in much‐needed advances in this field. Semin. Surg. Oncol. 21:223–227, 2003. © 2003 Wiley‐Liss, Inc.
An experimental and numerical approach to investigate the dynamic response of a four‐flue chimney of a thermo‐electrical plant
Authors: Cavacece Massimo , Valentini Pier Paolo 
Published: November 2003

AbstractThis paper describes an experimental procedure and a numerical model for the study of the dynamic behaviour of a chimney of a thermo‐electrical plant. The experimental part is based on the measurement of the structure's dynamic response by means of several accelerometers. Different signals from forced time‐periodic excitations, spanning a range of frequencies, have been collected and compared with those from a finite elements model. In particular, the first four modal shapes and their frequencies are computed. Following this validation, the finite element model has also been applied to investigate the response of the chimney subjected to a generic wind periodic excitation (vortex shedding). The numerical results show good agreement with the experimentally collected data. Copyright © 2003 John Wiley & Sons, Ltd.
A new procedure for the analysis of construction loads in multistory reinforced concrete structures
Authors: de Almeida Prado José Fernão Miranda , Corrêa Márcio Roberto Silva , Ramalho Marcio Antonio 
Published: November 2003

AbstractSummaryConstruction loads in a multistory reinforced concrete building are largely influenced by the construction schedule. These loads may exceed the designed strength of the building's structure or produce early cracking of the floor, with adverse consequences to its service conditions, because of amplifications of time‐dependent deflections. Fresh floors are supported by previously cast floors, using a formwork system with shores and reshores. The definition of floor loads, considering the construction sequence, provides an outlook of the load history on the structural elements from the beginning to the end of the construction work. Models for evaluating that phenomenon are very important and, as far as possible, should be simple and suitable for quick analysis. The present work proposes a new method to analyze the distribution of construction loads. This method is based on the experience of the authors in using finite elements in sequential structural analyses of multistory reinforced concrete buildings. Using the concept of primary structures, the new method offers a viable way of distributing construction loads between the formwork and the interconnected floors. Copyright © 2003 John Wiley & Sons, Ltd.