bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Properties and SSA Fractionation of Metallocene Ethylene‐Oct‐1‐ene Copolymers with High Comonomer Content Cross‐linked by Dicumyl Peroxide or β‐Radiation
Authors: Nicolás Javier , Villarreal Norky , Gobernado‐Mitre Isabel , Merino Juan C. , Pastor José M. 
Published: December 2003

AbstractTwo metallocene ethylene‐oct‐1‐ene copolymers, differing in comonomer content and in molecular weight, were cross‐linked either by dicumyl peroxide or β‐radiation. The effect of high comonomer content on the crystalline morphology, once the materials were cross‐linked, was analyzed by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The gel content was determined in boiling xylene, and the cross‐linking process was monitored by FT‐IR spectroscopy. Two endotherms were distinguished: the first one was associated to the primary crystallization, and the second one to the shorter sequences that are excluded from the primary crystallization. The successive self‐nucleation annealing (SSA) technique has revealed that as the comonomer content increases the crystal size distribution is more homogeneous, and therefore, the melting and crystallization behaviour is reversible, because of its fringed‐micellar morphology. In spite of their crystalline morphology with very low crystallites, DCP cross‐linked samples displayed a considerable decrease in crystallinity and in crystal size, whereas β‐irradiated samples showed no significant decline in crystal size. Slight changes in crystallinity were detected and attributed to the heat generation that every irradiation process involves and affects smaller crystallites preferentially. DMA analysis has confirmed DSC results on crystalline size and crystallinity variations induced by both cross‐linking processes. By means of FT‐IR spectroscopy, it was detected that a high comonomer content induces oxidation during cross‐linking. Moreover, β‐irradiation samples exhibited a lower degree of oxidation than DCP cross‐linked samples.The heating scan of DCP cross‐linked EG8411 after being submitted to successive self‐nucleation annealing.magnified imageThe heating scan of DCP cross‐linked EG8411 after being submitted to successive self‐nucleation annealing.
Optical Proof of Mesophase Transitions between Smectic and Nematic Phase of the Side‐Group Polyacrylate PAC6
Authors: Weh Lothar 
Published: December 2003

AbstractThe liquid‐crystalline side‐group polyacrylate PAC6 forms two mesophases in thin layers within the temperature range between 90 and 100 °C. The structures developing by self‐organization can be made clearly visible by Schlieren‐optical methods. If a low lateral temperature gradient is maintained in the temperature range mentioned above one can simultaneously and abreast observe four phases in PAC6 layers. Both new phases occur between the smectic and the nematic phase. Layer surface deformations arise during this phase transition. They were analyzed with a microscope interferometer. The PAC6 melt shows a considerable change of surface tension in this temperature range.Schlieren‐optical image of a PAC6 layer with two mesophases.magnified imageSchlieren‐optical image of a PAC6 layer with two mesophases.
Effect of Cyclic Deformations on the Dynamic‐Mechanical Properties of Silica‐Filled Butyl Rubber
Authors: Ward Azza A. M. , Stoll Bernhard , von Soden Wolfgang , Herminghaus Stephan , Mansour Ashraf Ahmed 
Published: December 2003

AbstractThe effect of the chemical modification of the silica surface by the silane coupling agent (Si69) on both the real and the imaginary parts of the shear compliance (J′, J″) on silica‐filled butyl rubber vulcanizates was investigated in a wide temperature and frequency range, −70 to 120 °C and 10−4 to 10 Hz, respectively. In addition, the stress‐strain measurements, DSC, and TEM were carried out. Moreover the effect of stress‐strain cyclic deformation up to ten times with maximum deformation 80% of the elongation at break on J′, J″ is also studied. It was found that the filler network recovers after cyclic stress‐strain in a time scale of one year at room temperature.Transmission electron photographs of the butyl rubber [IIR] vulcanizates: (a) IIR, unfilled, (b) IIR, filled with 20 phr SiO2, (c) IIR,filled with 20 phr SiO2 + 1.6 phr Si69.magnified imageTransmission electron photographs of the butyl rubber [IIR] vulcanizates: (a) IIR, unfilled, (b) IIR, filled with 20 phr SiO2, (c) IIR,filled with 20 phr SiO2 + 1.6 phr Si69.
Atom Transfer Radical Block Copolymerization of 2‐(N,N‐Dimethylamino)ethyl Methacrylate and 2‐Hydroxyethyl Methacrylate
Authors: Jin Xiaopin , Shen Youqing , Zhu Shiping 
Published: December 2003

AbstractBlock copolymerization of 2‐(N,N‐dimethylamino)ethyl methacrylate (DMAEMA) with 2‐hydroxyethyl methacrylate (HEMA) via atom transfer radical polymerization (ATRP) was studied in methanol using a macroinitiator method and a “one‐pot” sequential addition method. The polymerization sequence of the two monomers strongly affected the block copolymer formation. When DMAEMA was used as the first monomer, both methods produced block copolymer samples containing significant amounts of DMAEMA homopolymer chains, because of the elimination of active halogen chain‐ends during the preparation of polyDMAEMA. Well‐controlled block copolymers with various block lengths were obtained via the macroinitiator method when polyHEMA was used as macroinitiator to initiate the polymerization of DMAEMA. The sequential addition method, in which HEMA was polymerized first with 90% conversion and DMAEMA was subsequently added, also yielded controlled block copolymers when the polymerization was carried out at room temperature with the DMAEMA conversion below 60%. Increasing the temperature to 60 °C promoted the copolymerization rate but the reaction suffered from gel formation. The addition of water to the system accelerated the polymerization rate, but led to the loss of the system livingness.Gel permeation chromatograms of poly(HEMA‐b‐DMAEMA). The samples were prepared in methanol at room temperature with different block molecular weights using the macroinitiator method.magnified imageGel permeation chromatograms of poly(HEMA‐b‐DMAEMA). The samples were prepared in methanol at room temperature with different block molecular weights using the macroinitiator method.
Preparation of Melamine Resin Micro/Nanocapsules by using a Microreactor and Telomeric Surfactants
Authors: Sawada Tsuyoshi , Korenori Misaki , Ito Katsuki , Kuwahara Yutaka , Shosenji Hideto , Taketomi Yoko , Park Soomin 
Published: December 2003

AbstractMelamine resin microcapsules were prepared by the batch method and microreactor method using sodium dodecyl sulfate (SDS) and 1.6R6A‐3.5AA as emulsifiers. They contained about 50% toluene as indicated by thermogravimetric (TG) analysis. The mean sizes of the microcapsules obtained by using the microreactor method with SDS and with 1.6R6A‐3.5AA were 462 ± 199 and 147 ± 31 nm, respectively. Microcapsules prepared by using a microreactor showed smaller particle diameters and a narrower particle size distribution than those obtained using a batch reactor.SEM photograph of a melamine resin microcapsule formed using a microreactor and the telomeric surfactant 1.6R6A‐3.5AA after mechanical scratching.magnified imageSEM photograph of a melamine resin microcapsule formed using a microreactor and the telomeric surfactant 1.6R6A‐3.5AA after mechanical scratching.
Existence of unbounded solutions to parabolic equations with functional dependence
Authors: Bychowska Agnieszka 
Published: December 2003

AbstractThe Cauchy problem for nonlinear parabolic differential‐functional equations is considered. Under natural generalized Lipschitz‐type conditions with weights, the existence and uniqueness of unbounded solutions is obtained in three main cases: (i) the functional dependence u(·); (ii) the functional dependence u(·) and ∂xu(·); (iii) the functional dependence u(·) and the pointwise dependence ∂xu(t, x). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Complex interpolation, minimal methods and compact operators
Authors: Cobos Fernando , Fernández‐Cabrera Luz M. , Martínez Antón 
Published: December 2003

AbstractWe characterize compact operators between complex interpolation spaces and between spaces obtained by using certain minimal methods in the sense of Aronszajn and Gagliardo. Applications to interpolation of compact operators are also given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel transports in webs
Authors: Fleischhack Christian 
Published: December 2003

AbstractFor connected reductive linear algebraic structure groups it is proven that every web is holonomically isolated. This means that all parallel transports, occurring in a web, may already be obtained by modifying an arbitrary connection in an arbitrarily given neighbourhood of the interior of such a set of paths. Moreover, it is shown that the possible tuples of parallel transports in a web form a Lie subgroup of the corresponding power of the structure group. This Lie subgroup is explicitly calculated and turns out to be independent of the chosen local trivializations. Additionally, explicit necessary and sufficient criteria for the holonomical independence of webs are derived. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On rank invariance of moment matrices of nonnegative Hermitian‐valued Borel measures on the unit circle
Authors: Fritzsche Bernd , Kirstein Bernd , Lasarow Andreas 
Published: December 2003

AbstractThis paper provides first tools for generalizing the theory of orthogonal rational functions on the unit circle 𝕋 created by Bultheel, González‐Vera, Hendriksen and Njåstad to the matrix case. A crucial part in this generalization is the definition of the spaces of matrix‐valued rational functions for which an orthogonal basis is to be constructed. An important feature of the matrix case is that these spaces will be considered simultaneously as left and right modules over the algebra ℂq×q. In this modules we will define simultaneously left and right matrix‐valued inner products with the aid of a nonnegative Hermitian‐valued q × q Borel measure on the unit circle. Given a sequence (αj)j∈ℕ of complex numbers located in ℂ\𝕋 (especially in “good position” with respect to the unit circle) we will introduce a concept of rank for nonnegative Hermitian‐valued q × q Borel measures on the unit circle which is based on the Gramian matrix of particular rational matrix‐valued functions with prescribed pole structure. A main result of this paper is that this concept of rank is universal. More precisely, it turns out that the rank of a matrix measure does not depend on the given sequence (αj)j∈ℕ. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase dynamics in the real Ginzburg‐Landau equation
Authors: Melbourne Ian , Schneider Guido 
Published: December 2003

AbstractSpatially periodic equilibria A(X, T) = √1 − q2 e are the locally preferred planform for the Ginzburg‐Landau equation ∂TA = ∂2XA + A − A|A|2. To describe the global spatial behavior, an evolution equation for the local wave number q can be derived formally. The local wave number q satisfies approximately a so called phase diffusion equation ∂τq = ∂2ξh(q). It is the purpose of this paper to explain the extent to which the phase diffusion equation is valid by proving estimates for this formal approximation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calculations of Monomer Conversion and Radical Concentration in Reversible Addition‐Fragmentation Chain Transfer Radical Polymerization
Authors: Wang Aileen R. , Zhu Shiping 
Published: December 2003

AbstractSimple expressions are derived for the development of monomer conversion, as well as propagating radical, adduct radical, dormant chain, and dead chain concentrations in reverse addition‐fragmentation transfer polymerization (RAFT). The relations for the profiles of propagating radical concentration and conversion versus time are derived and depend on group parameters of rate constants and chemical recipe. The analytical equations are verified against numerical solutions of the mass‐balance differential equations. This derivation involves the steady‐state hypothesis for radical and RAFT agent concentrations. The errors introduced by these assumptions are negligible when the fragmentation rate constant, kf, is higher than 10 s−1 or when the cross‐termination rate constant, kct, is higher than 105 L · mol−1 s−1.Calculated concentration profiles (points: numerical, lines: analytical) of propagating radical R, adduct radical A, dormant T, and dead D (= P + P′) chains.imageCalculated concentration profiles (points: numerical, lines: analytical) of propagating radical R, adduct radical A, dormant T, and dead D (= P + P′) chains.
Coil‐Globule Collapse in Flexible Macromolecules
Authors: Baysal Bahattin M. , Karasz Frank E. 
Published: December 2003

AbstractThe transition of a solvated flexible macromolecular chain from random coil behavior in the θ‐state to a globular compact form in the collapsed state has been the subject of extensive theoretical and experimental studies. Most of the coil‐globule transition studies of macromolecules have concentrated on the prototypical polystyrene‐cyclohexane system. However, chain contractions reported in this system have been around 75% of those in the unperturbed θ‐state. This relatively small decrease in size does not satisfy the criterion for a densely packed, collapsed globule. Experimentally, the collapse from a coil to a true compact globular state has now been established for two flexible macromolecules: poly(N‐isopropylacrylamide) in water and poly(methyl methacrylate) in various solvents. In this contribution, we review recent theoretical studies covering phenomenological and Langevin models as well as computer simulations. In addition, we outline recent experimental studies of the coil‐globule transition of various flexible polymers, copolymers, and polyelectrolytes.Expansion factor, α, versus temperature for NaPSS in 4.17 M aqueous NaCl solution. (•): NaPSS‐1, (○): NaPSS‐2.imageExpansion factor, α, versus temperature for NaPSS in 4.17 M aqueous NaCl solution. (•): NaPSS‐1, (○): NaPSS‐2.
Kinetic Evaluation of Hyperbranched A2 + B3 Polycondensation Reactions
Authors: Schmaljohann Dirk , Voit Brigitte 
Published: December 2003

AbstractThe kinetics of hyperbranched A2 + B3 systems is discussed theoretically with respect to the development of the 7 different structural units, the degree of branching, DB, and the monomer sequences considering the adjacent groups of a structural unit. For A2 + B3 systems, the comonomer ratio, the relative rate constants and the process conditions have an influence on the resulting structure as shown by numerical simulations. With increasing A:B ratios fA/B, the degree of branching will be increased. Also the relative reaction rate constants have a strong impact on the distribution of structural units, especially when the reaction rate constants for the pathway of the B3 monomer are changed. On the other hand, differences in the reaction rate constants for the pathway of the A2 monomer do not have any influence on the degree of branching. The simulation indicates that slow addition of either both monomers or just the B3 monomer has the strongest effect on the resulting DB. In all cases, the conversion is a critical issue to obtain high molecular weight products.Degree of branching (DB) versus conversion of A‐functionalities (pA) for various monomer compositions.imageDegree of branching (DB) versus conversion of A‐functionalities (pA) for various monomer compositions.
The molecular mechanism of sensitization to Fas‐mediated apoptosis by 2‐methoxyestradiol in PC3 prostate cancer cells
Authors: Shimada Keiji , Nakamura Mitsutoshi , Ishida Eiwa , Kishi Munehiro , Matsuyoshi Syuchi , Konishi Noboru 
Published: December 2003

AbstractIt is widely known that death receptor Fas‐dependent apoptotic signals are associated with development of prostate cancer, but the key pathways involved in sensitivity to the apoptosis remain unclear. Here we investigated the molecular mechanism by which 2‐methoxyestradiol (2‐ME) effectively sensitizes a human prostate cancer cell line, PC3, to Fas‐mediated apoptosis. 2‐ME significantly inhibited nuclear factor‐κB (NF‐κB) activation and downregulated Fas‐associated death domain (FADD) protein interluekin‐1beta‐converting enzyme inhibitory protein (FLIP). Overexpression of the dominant negative mutant form of IκBα (d/n IκBα) or treatment with Iκ kinase‐specific inhibitor Bay117082 gave the same results, although the sensitizing effect was not as pronounced. A selective inhibitor of Akt phosphorylation, LY294002, accelerated formation of the death‐inducing signaling complex (DISC) not only by FLIP reduction but also by enhancement of recruitment of the FADD to Fas, thereby sensitizing PC3 cells to apoptosis similar to the case with 2‐ME stimulation. Moreover, we found that inhibition of 2‐ME–induced extracellular signal‐regulated kinase (ERK) activation by the upstream kinase inhibitor PD98059 significantly enhanced 2‐ME–mediated suppression of Akt activation, resulting in much greater sensitization to apoptosis. Taken together, the present findings indicate that 2‐ME suppresses NF‐κB/FLIP signaling and enhances DISC formation through inhibition of Akt, and that PC3 cells thereby are being sensitized to Fas‐mediated apoptosis and by a process closely associated with ERK. © 2003 Wiley‐Liss, Inc.
CHFR‐associated early G2/M checkpoint defects in breast cancer cells
Authors: Erson Ayse E. , Petty Elizabeth M. 
Published: December 2003

AbstractCell division is a highly regulated process. Checkpoints can halt cell‐cycle progression due to adverse conditions such as misalignment of chromosomes to prevent missegregation. The search for new regulators of the cell cycle revealed the mitotic checkpoint gene CHFR (checkpoint with forkhead‐associated and ring finger). CHFR coordinates an early mitotic phase by delaying chromosome condensation in response to a mitotic stress. Because aneuploidy and chromosome instability are common in malignant breast tumors, we screened 24 breast cancer cell lines for CHFR expression and demonstrated that 50% (12 of 24) of breast cancer cell lines had low CHFR levels. Expression of CHFR was reactivated with the demethylating agent 5‐aza‐2′‐deoxycytidine (5‐aza‐dC) in two low‐CHFR–expressing cell lines. Eleven of these 12 (92%) low‐CHFR–expressing cell lines had an unusually high number of condensed chromosomes and high mitotic indices in response to nocodazole treatment. Transfection of CHFR in one of these cancer cell lines lowered the mitotic index after nocodazole treatment. In conclusion, our data suggested that low CHFR expression associated with high mitotic indices in response to nocodazole treatment were common in the breast cancer cell lines studied. Additional flow cytometry studies and analysis of a protein that interacts with CHFR in vitro, polo‐like kinase 1 (PLK1), suggests that this CHFR‐associated early G2/M checkpoint is complex, involving additional, as yet unidentified, proteins. Further analysis of CHFR in breast cancer cells will be important for understanding the complex mechanisms leading to aneuploidy and chromosomal instability observed in breast cancer. © 2003 Wiley‐Liss, Inc.
Adhesion, migration, transcriptional, interferon‐inducible, and other signaling molecules newly implicated in cancer susceptibility and resistance of JB6 cells by cDNA microarray analyses
Authors: Samuel Shaija , Bernstein Lori R. 
Published: December 2003

AbstractRelative expression levels of 9500 genes were determined by cDNA microarray analyses in mouse skin JB6 cells susceptible (P+) and resistant (P−) to 12‐O‐tetradecanoyl phorbol‐13 acetate (TPA)‐induced neoplastic transformation. Seventy‐four genes in 6 functional classes were differentially expressed: (I) extracellular matrix (ECM) and basement membrane (BM) proteins (20 genes). P+ cells express higher levels than P− cells of several collagens and proteases, and lower levels of protease inhibitors. Multiple genes encoding adhesion molecules are expressed preferentially in P− cells, including six genes implicated in axon guidance and adhesion. (II) Cytoskeletal proteins (13 genes). These include actin isoforms and regulatory proteins, almost all preferentially expressed in P− cells. (III) Signal transduction proteins (12 genes). Among these are Ras‐GTPase activating protein (Ras‐GAP), the deleted in oral cancer‐1 and SLIT2 tumor suppressors, and connexin 43 (Cx43) gap junctional protein, all expressed preferentially in P− cells. (IV) Interferon‐inducible proteins (3 genes). These include interferon‐inducible protein (IFI)‐16, an Sp1 transcriptional regulator expressed preferentially in P− cells. (V) Other transcription factors (4 genes). Paired related homeobox gene 2 (Prx2)/S8 homeobox, and retinoic acid (RA)‐regulated nur77 and cellular retinoic acid‐binding protein II (CRABPII) transcription factors are expressed preferentially in P− cells. The RIN‐ZF Sp‐transcriptional suppressor exhibits preferential P+ expression. (VI) Genes of unknown functions (22 sequences). Numerous mesenchymal markers are expressed in both cell types. Data for multiple genes were confirmed by real‐time PCR. Overall, 26 genes were newly implicated in cancer. Detailed analyses of the functions of the genes and their interrelationships provided converging evidence for their possible roles in implementing genetic programs mediating cancer susceptibility and resistance. These results, in conjunction with cell wounding and phalloidin staining data, indicated that concerted genetic programs were implemented that were conducive to cell adhesion and tumor suppression in P− cells and that favored matrix turnover, cell motility, and abrogation of tumor suppression in P+ cells. Such genetic programs may in part be orchestrated by Sp‐, RA‐, and Hox‐transcriptional regulatory pathways implicated in this study. © 2003 Wiley‐Liss, Inc.
Antisense blocking of BRCA1 enhances sensitivity to plumbagin but not tamoxifen in BG‐1 ovarian cancer cells
Authors: Srinivas Gopal , Annab Lois A. , Gopinath Gokul , Banerji Asoke , Srinivas Priya 
Published: December 2003

AbstractPrevious studies have shown that reduction in BRCA1 mRNA and protein can result in increased proliferation of BG‐1 ovarian cancer cells in both in vitro and in vivo conditions, suggesting that BRCA1 may normally act as a growth inhibitor in these cells. Also, there are other reports that suggest that wild‐type BRCA1 protein may repress estrogen receptor (ER) function either directly or indirectly. However, response to antiestrogen drugs in BRCA1‐blocked ER‐positive ovarian cancer cells has not been reported, and this served as the rationale for this study. We analyzed the effect of tamoxifen, emodin, and plumbagin in BRCA1‐blocked ER‐positive BG‐1 ovarian cancer cells. For all three drugs, BRCA1‐blocked cells were more sensitive than the corresponding control cells as assessed by MTT assay; however, only plumbagin showed a statistically significant difference in mean viability (P < 0.05). All three drugs induced loss of mitochondrial membrane potential (ΔΨm), nuclear condensation, DNA fragmentation, and morphological changes, as observed after 6 h of drug treatment, suggesting apoptosis induction in both BRCA1‐blocked and control cells. However, apoptosis induction was greater in BRCA1‐blocked cells, the efficacy being in the order of plumbagin > tamoxifen > emodin. The dose of plumbagin needed to kill 50% was 5 μM in the control cells and 2.68 μM for the BRCA1‐blocked cells, indicating that the latter was about twofold more sensitive to plumbagin than the wild‐type cells. This throws light on the fact that plumbagin may have chemotherapeutic potential as an anticancer agent in BRCA1‐mutated ovarian cancer patients. © 2003 Wiley‐Liss, Inc.