bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modification of properties of CaCO3‐polymerization‐filled polyethylene
Authors: Novokshonova L. A. , Meshkova I. N. , Ushakova T. M. , Grinev V. G. , Ladigina T. A. , Gultseva N. M. , Kudinova O. I. , Boer S. De 
Published: November 2002

AbstractCaCO3–polyethylene (PE) compositions, containing an ultrahigh molecular polyethylene (UHMPE) interlayer between the filler surface and the PE matrix, were synthesized by two‐step polymerization of ethylene on a filler surface activated with a suitable catalyst. The properties of the compositions were studied depending on the molecular weight of the PE matrix and the thickness of the UHMPE intermediate layer at the filler particles. It was shown that the presence of UHMPE as an interlayer in chalk–UHMPE–PE compositions leads to an increase of plastic deformation of the materials as long as the Mw value of the PE matrix is higher than is the brittleness threshold for PE. Chalk–UHMPE–PE compositions exhibit a higher ability for plastic deformation compared to chalk–PE compositions based on a PE matrix of a molecular weight equal to the molecular weight of the total polymer phase (UHMPE–PE) in the first case. There is no improvment of the mechanical properties when the UHMPE is dispersed in the compositions and not as an interlayer between a filler and a matrix. This means that the method of polymerization filling allows one to incorporate the polymer interlayer with a desired nature and properties between a filler surface and polymer matrix in filled polyolefin compositions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 577–583, 2003
Synthesis and photosensitivity of acryloylmorpholine copolymers with a pendant (meth)acryloyl group
Authors: Ninomiya Atsuyuki , Yoshimura Hikoji 
Published: November 2002

AbstractWe have developed new photopolymers that have superior waterproof properties and that can easily interact with polyfunctional acrylate compounds, thus serving as hydrophobic photocrosslinking reagents. Acryloylmorpholine monomers whose homopolymers were less moisture absorbing than the usual water‐soluble polymers but were still water soluble to a good degree, were copolymerized with other acryloyl monomers. We then introduced the photosensitive (meth)acryloyl group to side chains of the resulting polymers. Among six copolymers examined, the copolymers composed of acryloyl morpholine, hydroxyethyl acrylate, ethyl, or methyl methacrylate, and methacryloyl isocyanate were found to have nicely balanced hydrophilicity and waterproof properties, in addition to good compatibility with hydrophobic photocrosslinking reagents. The composite polymers thus obtained were confirmed to be promising photopolymers usable even in a highly humid environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 684–692, 2003
Swelling and drying kinetics of polytetrahydrofuran and polytetrahydrofuran–poly (methyl methacrylate) gels: A photon transmission study
Authors: Yildiz Sevtap , Hepuzer Yeşim , Yağci Yusuf , Pekcan Önder 
Published: November 2002

AbstractA bifunctional polytetrahydrofuran (PTHF) macromonomer was synthesized by termination of the living polymerization of tetrahydrofuran (THF) initiated by triflic anhydride and the subsequent termination by sodium methacrylate. The PTHF macromonomer thus prepared was polymerized and copolymerized with methyl methacrylate (MMA) by free‐radical polymerization to yield a network and a segmented network of PTHF, both being homogeneous, respectively. These PTHF and PTHF–PMMA gels were used for swelling experiments in chloroform and chloroform vapor. Drying processes were monitored after removing the gels from the solvent and solvent vapor. Photon transmission from PTHF and PTHF–PMMA gels was monitored during swelling and drying processes using a UV‐visible (UVV) spectrophotometer. Transmitted light intensities, Itr, from these gels increased when they were immersed in chloroform and/or subjected to its vapor. The increase in Itr was attributed to the homogeneous lattice structure of PTHF and PTHF–PMMA gels which appeared during swelling. The increase in Itr was modeled using the Li–Tanaka equation from which time constants, τ1, and cooperative diffusion coefficients, DC, were determined. A decrease in Itr after removing choloform and/or its vapor from the cell was observed and attributed to the decrease in homogeneity of lattice structures during drying of the corresponding gels. Time constants, τ2, for the drying processes were also determined. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 632–640, 2003
Effect of hydroxypropyl cellulose in epoxy network formation
Authors: Miranda M. I. G. , Jacobs C. A. B. , Bica C. I. D. , Samios D. 
Published: November 2002

AbstractStudies on the curing reactions of epoxy systems were carried out in the presence of a cellulose derivative, hydroxypropyl cellulose (HPC). The technique of differential scanning calorimetry (DSC) was applied to characterize the curing reactions/thermal properties. Classical nonisothermal kinetic methods, such as the Kissinger and the Osawa methods (multiple scan) and the Barrett method (single scan) as well as the recently one proposed by Samios et al., were applied to study the reaction kinetics of the epoxy system of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐diaminodiphenylmethane (DDM) with HPC. The Barrett method gives additional information about the process of initiation, gelation, and vitrification. At the beginning of the epoxy curing reaction, HPC acts as a catalyst so that the energy of activation diminishes and the reaction occurs at lower temperatures. Above the minimum temperature Tmin, it was concluded that HPC behaves as an inhibitor of the reaction (Tmin is the temperature which corresponds to the minimum point showed by the exotermic peaks during the curing reaction of an epoxy resin measured by DSC). By analyzing the behavior of the kinetic parameters, Ea, k, and ln A, the molecular interactions were shown to be related to the catalyst–inhibitor characteristics of HPC. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 676–683, 2003
Role of endogenous regucalcin in nuclear regulation of regenerating rat liver: Suppression of the enhanced ribonucleic acid synthesis activity
Authors: Tsurusaki Yoshinori , Yamaguchi Masayoshi 
Published: November 2002

AbstractThe role of endogenous regucalcin in the regulation of ribonucleic acid (RNA) synthesis activity in the nucleus of normal and regenerating rat livers was investigated. Nuclear RNA synthesis was measured by the incorporation of [3H]‐uridine 5′‐triphosphate into the nuclear RNA in vitro. The presence of regucalcin (0.25 or 0.5 μM) in the reaction mixture caused a significant decrease in nuclear RNA synthesis of normal rat liver. α‐Amanitin (10−8–10−6 M), an inhibitor of RNA polymerase II and III, decreased significantly nuclear RNA synthesis activity. The effect of regucalcin (0.25 μM) in decreasing nuclear RNA synthesis activity was not seen in the presence of α‐amanitin (10−6 M). The calcium chloride (10 μM)‐increased nuclear RNA synthesis activity was significantly suppressed by the addition of regucalcin (0.25 μM). RNA synthesis activity was significantly enhanced in the nuclei of regenating rat liver obtained at 24, 48, or 72 h after partial hepatectomy. This enhancement was significantly inhibited in the presence of PD98059 (10−5 M), staurosporine (10−6 M), or vanadate (10−3 M). Western analysis of the nuclei of regenerating liver obtained at 24, 48, or 72 h after partial hepatectomy showed a significant increase in regucalcin protein as compared with that of sham‐operated rats. The presence of anti‐regucalcin monoclonal antibody (25 or 50 ng/ml) in the reaction mixture caused a significant increase in nuclear RNA synthesis activity of normal rat liver. This increase was completely blocked by the addition of regucalcin (1.0 μM). The effect of anti‐regucalcin monoclonal antibody (50 ng/ml) in increasing nuclear RNA synthesis activity was significantly enhanced in the nuclei of regenerating liver obtained at 24, 48, or 72 h after partial hepatectomy. This enhancement was significantly suppressed by the addition of α‐amanitin (10−6 M), PD98059 (10−5 M), staurosporine (10−6 M), or vanadate (10−3 M) in the reaction mixture. The present study demonstrates that endogenous regucalcin has a suppressive effect on the enhancement of RNA synthesis activity in the nucleus of regenerating rat liver with proliferative cells. J. Cell. Biochem. 87: 450–457, 2002. © 2002 Wiley‐Liss, Inc.
Transcriptional regulation restricting bone sialoprotein gene expression to both hypertrophic chondrocytes and osteoblasts
Authors: Barnes George L. , Torre Thomas Della , Sommer Beatrice , Young Marian F. , Gerstenfeld Louis C. 
Published: November 2002

AbstractThis study identifies a cis‐acting element that confers tissue‐restricted expression to the bone sialoprotein (BSP) gene. Using both gain of function and loss‐of function studies, we demonstrate that this element acts as a tissue specific enhancer of BSP expression in osteoblasts and hypertrophic chondrocytes but does not function in non‐hypertrophic chondrocytes or fibroblasts. Furthermore, our data demonstrate that binding of this element occurs in correlation with active BSP expression. While Dlx5 has been implicated as the tissue‐specific regulator of BSP expression through direct DNA binding at an element with homology to the one under study here, our results demonstrate that Dlx5 does not act as a positive regulator of BSP expression. Finally, mutational analyses of this element demonstrate that while there is homology to putative homeodomain binding elements, this site is unlikely to bind homeodomain factors including Dlx5. Thus, these studies identify an important cis‐acting element in the BSP promoter that acts as a tissue‐specific enhancer of BSP expression in both osteoblasts and hypertrophic chondrocytes. As such this is the first demonstration of a common regulatory mechanism utilized by both chondrocytes and osteoblasts for the tissue‐restricted expression of the BSP gene. J. Cell. Biochem. 87: 458–469, 2002. © 2002 Wiley‐Liss, Inc.
Crystal structures of human antibodies: a detailed and unfinished tapestry of immunoglobulin gene products
Authors: Ramsland Paul A. , Farrugia William 
Published: November 2002

AbstractSequencing of all human immunoglobulin (Ig) germline gene segments has recently been completed. However, our first glimpses of the recombined products of this combinatorial gene system were in the 1970s, in landmark publications, reporting the crystal structures of two human myeloma proteins, the Mcg λ light chain dimer and the New IgG1(λ) Fab. Although numerous crystal structures of murine and human antibodies have now been determined, only a relatively small proportion of the human germline genes have had their corresponding protein three‐dimensional structures resolved. Therefore, further structural investigations are required before the inherent diversity of the antibody repertoire can be fully appreciated. We discuss the detailed structural information available for human antibodies with regard to their immune functions. Also discussed, is how the structural information is finding application in the ‘humanization’ of murine antibodies as part of their development as ‘biopharmaceuticals’ for the treatment of human disease. Copyright © 2002 John Wiley & Sons, Ltd.
Mcg in 2030: new techniques for atomic position determination of immune complexes
Authors: Hanson B. Leif , Bunick Gerard J. , Harp Joel M. , Edmundson Allen B. 
Published: November 2002

AbstractThe λ‐type light chain dimer from a patient (Mcg) with multiple myeloma and amyloidosis was a pioneer protein for determining the three‐dimensional structures of immunoglobulins, understanding the effects of ligand binding, and exploring the use of combinatorial methods to identify novel peptides complementary to protein active sites. Despite 30 years of intense study, there are still unanswered questions about the structure of the Mcg dimer, especially with respect to positions of hydrogen atoms and solvent molecules. In the present report, we describe two techniques that will help define the roles of solvent in ligand interactions and complex formation with this immunoglobulin fragment: (1) introduction of helium as a cryogenic agent during X‐ray data collection; and (2) addition of neutron diffraction analyses. These techniques should provide improved resolution, and a more accurate structure of the Mcg dimer. Resolution enhancements of 0.5 Å have been achieved in preliminary experiments with cryogenic helium, as compared with the best X‐ray diffraction data obtained previously. In the near future, neutron diffraction studies should produce the first hydrogen structure for the Mcg dimer and help elucidate the ligand preferences and amyloidogenic properties of this eminently useful protein. Copyright © 2002 John Wiley & Sons, Ltd.
Standard and micro Genetic Algorithm optimization of profiled corrugated horn antennas
Authors: Sinton Seelig , Robinson Jacob , Rahmat‐Samii Yahya 
Published: November 2002

AbstractThe Genetic Algorithm (GA) optimization technique is applied to the optimization of a profiled corrugated horn, designed as a feed for a space‐borne remote sensing reflector‐antenna system. In addition to using the standard GA (SGA) optimization technique, a profiled corrugated horn is also designed and analyzed using micro GA (μGA). A comparative study has been performed among the various designs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 449–453, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10635
Radiation from a traveling‐wave current sheet at the interface between a conventional material and a metamaterial with negative permittivity and permeability
Authors: Alu Andrea , Engheta Nader 
Published: November 2002

AbstractIn this paper, we present an analysis for the radiation from a traveling‐wave infinitely‐extent sheet of monochromatic electric current that is placed at the interface between a conventional lossless dielectric and a lossless material possessing negative real permittivity and permeability. The field distributions and the direction of the Poynting vectors in both half spaces are discussed, and some physical remarks are provided. A brief note about launching Zenneck waves by a line current along this interface is also mentioned. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 460–463, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10638
Solution of a time‐domain magnetic‐field integral equation for arbitrarily closed conducting bodies using an unconditionally stable methodology
Authors: Chung Young‐seek , Sarkar Tapan K. , Jung Baek Ho 
Published: November 2002

AbstractIn this work, we present a new and efficient numerical method to obtain an unconditionally stable solution for the time‐domain magnetic‐field integral equation (TD‐MFIE) for arbitrarily closed conducting bodies. This novel method does not utilize the customary marching‐on‐in‐time (MOT) solution method often used to solve a hyperbolic partial‐differential equation. Instead, we solve the wave equation by expressing the transient behaviors in terms of weighted Laguerre polynomials. By using these orthonormal basis functions for the temporal variation, the time derivatives in the TD‐MFIE formulation can be handled analytically. Since these weighted Laguerre polynomials converge to zero as time progresses, the electric surface currents also converge to zero when expanded in a series of weighted Laguerre polynomials. In order to solve the wave equation, we introduce two separate testing procedures: spatial and temporal testing. By introducing the temporal testing procedure first, the marching‐on in time procedure is replaced by a recursive relation between the different orders of the weighted Laguerre polynomials. The other novelty of this approach is that through the use of the entire domain Laguerre polynomials for the expansion of the temporal variation of the currents, the spatial and the temporal variables can be separated. To verify our method, we do a comparison with the results of an inverse Fourier transform of a frequency domain MFIE. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 493–499, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10647
Origin of the chemical shift in X‐ray absorption near‐edge spectroscopy at the Mn K‐edge in manganese oxide compounds
Authors: de Vries A. H. , Hozoi L. , Broer R. 
Published: November 2002

AbstractThe absorption edge in Mn K‐edge X‐ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO3 to CaMnO3. On the other hand, in X‐ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the observed chemical shifts, 1s ionization as well as 1s → “4p” transition energies have been determined by electronic structure calculations on embedded Mn ions and embedded MnO6 clusters. Systematic variation of the cluster geometry and the cluster embedding showed that the chemical shifts are predominantly determined by two effects: the changes in the Mn 3d occupation and the changes in the Madelung potential. The large chemical shift in the 1s → 4p transition energies between different materials occurs because the two effects do not compensate each other. The chemical shifts obtained for the embedded MnO6 clusters agree reasonably with the experimental shifts. The small sensitivity to the material observed for the Mn 1s ionization energies is explained by the near cancellation of the effects of the Madelung potential and the 3d occupation of the Mn ion. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
An event routing service for distributed applications: computer telephony—a case study
Authors: Klimek Bartosz , Radziszowski Dominik , Zieliński Krzysztof 
Published: November 2002

AbstractThis paper presents an event routing service (ERS) that represents a pattern for the establishment and processing of lightweight sessions between a source and a destination of events. It is based on the CORBA notification service. To illustrate the features of the proposed service, its application in computer telephony is discussed in detail. Most of the positive features of the ERS are inherited from the CORBA notification service, but its implementation requires a novel protocol describing the lightweight session establishment mechanism. The implementation of ERS is described and its application to routing events in a computer telephony system is presented. The paper concludes with a performance measurement study. Copyright © 2002 John Wiley & Sons, Ltd.
Identification of the
cis
-Acting Site Involved in Activation of Promoters Regulated by Activity of the Type III Secretion Apparatus in
Shigella flexneri
Authors: Mavris Maria , Sansonetti Philippe J. , Parsot Claude 
Published: November 2002

ABSTRACT

Bacteria of
Shigella
spp. use a virulence plasmid-encoded type III secretion (TTS) system to invade the colonic epithelium in humans. The activity of the TTS apparatus is tightly regulated in the wild-type strain and is induced upon contact of bacteria with epithelial cells, whereas it is deregulated, i.e., constitutively active, in some mutants. Under conditions of deregulated secretion, approximately 20 proteins are secreted, including VirA, OspB to OspG, and at least three members of the IpaH family, all of which are encoded by the virulence plasmid. Conditions inducing or deregulating the activity of secretion also induce the transcription of
virA
and four
ipaH
genes. The transcription of
virA
and
ipaH9
.
8
requires both MxiE, a transcriptional activator of the AraC family, and IpgC, the chaperone of IpaB and IpaC, acting as a coactivator. Using reporter plasmids containing
lacZ
transcriptional fusions, we showed that the
ipaH7.8. ipa4
.
5. ospC1
, and
ospF
promoters are activated under conditions of deregulated secretion and that both MxiE and IpgC are necessary and sufficient for their activation in both
Shigella flexneri
and
Escherichia coli
. Promoter mapping and deletion analysis of the
ipaH9
.
8. virA
, and
ospC1
promoters identified a 17-bp motif, the MxiE box, which overlaps the −35 region and is essential for the activation of these promoters. The presence of eight MxiE boxes on the virulence plasmid suggests that 11 genes encoding secreted proteins may be regulated by the activity of secretion. We also present evidence that at least one
ipaH
gene that is carried by the chromosome is controlled by MxiE and IpgC.
Role for
radA/sms
in Recombination Intermediate Processing in
Escherichia coli
Authors: Beam Cynthia E. , Saveson Catherine J. , Lovett Susan T. 
Published: November 2002

ABSTRACT

RadA/Sms is a highly conserved eubacterial protein that shares sequence similarity with both RecA strand transferase and Lon protease. We examined mutations in the
radA/sms
gene of
Escherichia coli
for effects on conjugational recombination and sensitivity to DNA-damaging agents, including UV irradiation, methyl methanesulfonate (MMS), mitomycin C, phleomycin, hydrogen peroxide, and hydroxyurea (HU). Null mutants of
radA
were modestly sensitive to the DNA-methylating agent MMS and to the DNA strand breakage agent phleomycin, with conjugational recombination decreased two- to threefold. We combined a
radA
mutation with other mutations in recombination genes, including
recA
,
recB
,
recG
,
recJ
,
recQ
,
ruvA
, and
ruvC
. A
radA
mutation was strongly synergistic with the
recG
Holliday junction helicase mutation, producing profound sensitivity to all DNA-damaging agents tested. Lesser synergy was noted between a mutation in
radA
and
recJ
,
recQ
,
ruvA
,
ruvC
, and
recA
for sensitivity to various genotoxins. For survival after peroxide and HU exposure, a
radA
mutation surprisingly suppressed the sensitivity of
recA
and
recB
mutants, suggesting that RadA may convert some forms of damage into lethal intermediates in the absence of these functions. Loss of
radA
enhanced the conjugational recombination deficiency conferred by mutations in Holliday junction-processing function genes,
recG
,
ruvA
, and
ruvC
. A
radA recG ruv
triple mutant had severe recombinational defects, to the low level exhibited by
recA
mutants. These results establish a role for RadA/Sms in recombination and recombinational repair, most likely involving the stabilization or processing of branched DNA molecules or blocked replication forks because of its genetic redundancy with RecG and RuvABC.
Signal Sequence Mutations as Tools for the Characterization of LamB Folding Intermediates
Authors: Duguay Amy Rizzitello , Silhavy Thomas J. 
Published: November 2002

ABSTRACT

lamBA23DA25Y
and
lamBA23YA25Y
tether LamB to the inner membrane by blocking signal sequence processing. We isolated suppressors of
lamBA23DA25Y
and
lamBA23YA25Y
, all of which mapped within the LamB signal sequence. Most interesting were mutations that changed an amino acid with a strong positive charge to an amino acid with no charge. Further characterization of two such suppressors revealed that they produce functional LamB that is localized to the outer membrane with its entire signal sequence still attached. Biochemical analysis shows that mutant LamB monomer chases into an oligomeric species with properties different from those of wild-type LamB trimer. Because assembly of mutant LamB is slowed, these mutations provide useful tools for the characterization of LamB folding intermediates.