bluuebunny/crossref_metadata_2025 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

Two 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.

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The 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

The 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.

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Schlieren‐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

The 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.

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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.
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

Block 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.

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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.
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

Melamine 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.

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SEM 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

The 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

We 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

For 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

This 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)
Regular and absolutely regular Hankel‐transformable distributions
Authors: Marrero I.
Published: December 2003

We describe the spaces of regular and absolutely regular Hankel‐transformable distributions and discuss their interrelations. Several topologies on those spaces are proposed and examined. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase dynamics in the real Ginzburg‐Landau equation
Authors: Melbourne Ian , Schneider Guido
Published: December 2003

Spatially 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

Simple 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.

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Calculated 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

The 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.

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Expansion 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

The 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.

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Degree 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

It 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

Cell 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

Relative 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

Previous 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.
A Wiener–Hopf approximation technique for a multiple plate diffraction problem
Authors: Brannan James R. , Ervin Vincent J. , Duan Jinqiao , Razoumov Leonid
Published: December 2003

An approximation method is derived for the computation of the acoustic field between a series of parallel plates, subject to a time periodic incident field. The method is based on the Wiener–Hopf method of factorization, with computations involving orthogonal bases of functions that are analytic in the complex half‐plane. Copyright 2004 John Wiley & Sons, Ltd.
Index transforms associated with generalized hypergeometric functions
Authors: Yakubovich Semyon B.
Published: December 2003

We deal with a class of integral transformations whose kernels contain the Clausenian hypergeometric function 3F2(a1,a2,a3;b1,b2;z). These transforms are defined in terms of integrals with respect to their parameters. It involves as particular cases the familiar Olevskii and generalized Mehler–Fock transforms which are key tools in the methods of the mathematical theory of elasticity. The main theorem of boundedness of these operators as a map of L2(ℝ+)L2(ℝ+;x−1 dx) is proved. Some examples of the Olevskii and Mehler–Fock type integrals are given. Copyright © 2003 John Wiley & Sons, Ltd.
Boundary position feedback control of Kirchhoff's non‐linear strings
Authors: Kobayashi Toshihiro
Published: December 2003

This paper is concerned with global stabilization of an undamped non‐linear string in the case where any velocity feedback is not available. The linearized system has an infinite number of poles and zeros on the imaginary axis. In the case where any velocity feedback is not available, a parallel compensator is effective. The stabilizer is constructed for the augmented system which consists of the controlled system and a parallel compensator. It is proved that the string can be stabilized by linear boundary control. Copyright © 2003 John Wiley & Sons, Ltd.
Solution representations for a wave equation with weak dissipation
Authors: Wirth Jens
Published: December 2003

We consider the Cauchy problem for the weakly dissipative wave equation □v+μ/1+t
vt=0,
x∈ℝn, t≥0 parameterized by μ>0, and prove a representation theorem for its solutions using the theory of special functions.

This representation is used to obtain Lp–Lq estimates for the solution and for the energy operator corresponding to this Cauchy problem.

Especially for the L2 energy estimate we determine the part of the phase space which is responsible for the decay rate. It will be shown that the situation depends strongly on the value of μand that μ=2 is critical. Copyright © 2004 John Wiley & Sons, Ltd.
Single dopant diffusion in semiconductor technology
Authors: Glitzky A. , Merz W.
Published: December 2003

The paper deals with the analysis of pair diffusion models in semiconductor technology. The underlying model contains reaction‐drift‐diffusion equations for the mobile point defects and dopant‐defect pairs as well as reaction equations for immobile dopants which are coupled with a non‐linear Poisson equation for the chemical potential of the electrons. For homogeneous structures we present an existence and uniqueness result for strong solutions. Starting with energy estimates we derive further a priori estimates such that fixed point arguments due to Leray–Schauder guarantee the solvability of the model equations. Copyright © 2004 John Wiley & Sons, Ltd.
Approximation by herglotz wave functions
Authors: Weck Norbert
Published: December 2003

By a general argument, it is shown that Herglotz wave functions are dense (with respect to the C∞(Ω)‐topology) in the space of all solutions to the reduced wave equation in Ω. This is used to provide corresponding approximation results in global spaces (eg. in L2‐Sobolev‐spaces Hm(Ω)) and for boundary data. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical simulation of the non‐linear crack problem with non‐penetration
Authors: Kovtunenko Victor A.
Published: December 2003

Here the numerical simulation of some plane Lamé problem with a rectilinear crack under non‐penetration condition is presented. The corresponding solids are assumed to be isotropic and homogeneous as well as bonded. The non‐linear crack problem is formulated as a variational inequality. We use penalty iteration and the finite‐element method to calculate numerically its approximate solution. Applying analytic formulas obtained from shape sensitivity analysis, we calculate then energetic and stress characteristics of the solution, and describe the quasistatic propagation of the crack under linear loading. The results are presented in comparison with the classical, linear crack problem, when interpenetration between the crack faces may occur. Copyright © 2004 John Wiley & Sons, Ltd.
Global smooth solution of hydrodynamical equation for the Heisenberg paramagnet
Authors: Boling Guo , Yongqian Han
Published: December 2003

In this note, we obtain the existence and uniqueness of global smooth solution for the Cauchy problem of multidimensional hydrodynamical equation for the Heisenberg paramagnet. Copyright © 2004 John Wiley & Sons, Ltd.
3‐D Contact problems for elastic wedges with Coulomb friction
Authors: Bach Michael , Pozharskii Dmitri
Published: December 2003

3‐D quasi‐static contact problems for elastic wedges with Coulomb friction are reduced to integral equations and integral inequalities with unknown contact normal pressures. To obtain these equations and inequalities, Green's functions for the wedges, where one face of the wedges is either stress‐free or fixed, are needed. Using Fourier and Kontorovich–Lebedev integral transformations, all the stresses and displacements in the wedges can be constructed in terms of solutions of Fredholm integral equations of the second kind on the semiaxis. The Green's functions can be calculated as uniformly convergent power series in (1‐2ν), where νis Poisson's ratio. An exponential decay of the kernels and right‐hand sides of the Fredholm integral equations provides the applicability of the collocation method for simple and fast calculation of the Green's functions. For a half‐space, which is a special case of an elastic wedge, the kernels degenerate and the functions reduce to the well‐known Boussinesq and Cerruti solutions.

Analysing the contact problems reveals that the Green's functions govern the kernels of the above mentioned integral equations and inequalities. Under the assumption that the punch has a smooth shape, the contact pressure is zero on the boundary of the unknown contact zone. Solving the contact problems with the help of the Galanov–Newton method, the normal contact pressure, the contact zone and the normal displacement around the contact zone can be determined simultaneously. In view of the numerical results, the influence of the friction forces on the punch force and the punch settlement is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
On the non‐stationary Maxwellians
Authors: Gordevskyy V. D.
Published: December 2003

The exact Maxwell solutions of the non‐linear Boltzmann equation which have the most general form are studied. They are inhomogeneous and non‐stationary and describe rather complex motions of a rarefied gas. The classification of all possible types of these motions is obtained with a detailed analysis of the geometrical and physical features of the corresponding flows in a gas. In particular, the rotating and flying translational flows have non‐symmetric structure with two different axes: the axis of velocities and the axis of the density. The approximate description of the interaction between such flows by the bimodal distributions of a special form for the model of hard spheres is also obtained. Copyright © 2004 John Wiley & Sons, Ltd.
Messenger RNA stockpile of cyclin B, insulin‐like growth factor I, insulin‐like growth factor II, insulin‐like growth factor receptor Ib, and p53 in the rainbow trout oocyte in relation with developmental competence
Authors: Aegerter Sandrine , Jalabert Bernard , Bobe Julien
Published: December 2003

In the present study, correlations between the oocyte messenger RNA (mRNA) stockpile of Cyclin B, insulin‐like growth factor I (IGF‐I), insulin‐like growth factor (IGF‐II), insulin‐like growth factor receptor Ib (IGFR Ib), and p53 transcripts and the developmental competence of the oocyte were studied. For this purpose, post‐ovulatory ageing was used as a tool to generate oocytes of varying developmental competence. Mature female rainbow trout were held at 12°C and periodically checked for ovulation. Oocytes were collected from each female at ovulation and 5, 14, 21 days later. For each collected egg batch, the abundance of several mRNAs in the oocyte was analyzed by real‐time PCR and embryo development was monitored after fertilization. Egg quality was estimated not only through embryonic survival but also by studying the occurrence of specific morphological abnormalities. The present study showed that oocyte post‐ovulatory ageing was associated with variations of the relative abundance of several studied transcripts within the oocyte. In addition, the abundance of specific mRNAs could be correlated with either the embryonic survival or the occurrence of malformations. Thus, the abundance of IGFR Ib and Cyclin B transcripts in the oocyte was correlated with the occurrence of morphological abnormalities observed at yolk‐sac resorption (negatively for IGFR Ib and positively for Cyclin B), while the maternal stockpile of IGF‐I, IGF‐II, and IGFR Ib mRNAs was positively correlated with embryonic survival. Mol. Reprod. Dev. 67:127–135, 2004. © 2004 Wiley‐Liss, Inc.
Analysis of differential maternal mRNA expression in developmentally competent and incompetent bovine two‐cell embryos
Authors: Fair Trudee , Murphy Madeline , Rizos Dimitrios , Moss Catherine , Martin Finian , Boland Maurice P. , Lonergan Patrick
Published: December 2003

The main objective of this study was to identify mRNA transcripts associated with embryonic developmental competence. In cattle, mRNA transcripts, ribosomes, and proteins accumulated during the growth phase are drawn on to sustain maturation, fertilization, and the initial cell cycle divisions up to the 8‐ to 16‐cell stage. Early cleaving mammalian zygotes are more likely to develop to the blastocyst stage than their later cleaving counterparts, thus reflecting the intrinsic quality of the oocytes from which they originated. We describe the combination of this well‐established model for the retrospective determination of developmental competence in mammalian oocytes with a technique for wide screening of differential gene expression in different biological populations. Immature cumulus oocyte complexes were recovered from surface visible follicles on abattoir ovaries, washed, and submitted to routine in vitro maturation and fertilization. Two‐cell embryos were removed from culture at 3‐hr intervals from 24 to 42 hr post insemination (pi). Two populations of two‐cell embryos were identified; those that cleaved early (before 27 hpi) and those that cleaved late (after 33 hpi). Suppressive subtractive hybridization was carried out on cDNA from the two populations, following which, differentially expressed amplicons were subcloned and sequenced. The sequences were submitted to the nonredundant and expressed sequence tag (EST) databases at NCBI using the BLAST algorithm. The differential expression of three selected candidate genes that were identified as putatively upregulated in the early cleaving zygotes were chosen for further investigations; histone H3, cyclin B1, and GDF‐9B. Using quantitative real time PCR we have shown that histone H3A is significantly more abundant in embryos that cleave earliest. Mol. Reprod. Dev. 67:136–144, 2004. © 2004 Wiley‐Liss, Inc.
Expression and localization of fibroblast growth factor (FGF) family members during the final growth of bovine ovarian follicles
Authors: Berisha Bajram , Sinowatz Fred , Schams Dieter
Published: December 2003

The aim of this study was to investigate the possible participation of fibroblast growth factor (FGF) family members: FGF1, FGF2, and FGF7, and their receptor variants: FGFR, FGFR2IIIb, and FGFR2IIIc in theca interna (TI) and granulosa cell (GC) compartments of bovine follicles during final growth. A classification of follicles into five groups (<0.5; >0.5–5; >5–20; >20–180; >180 ng/ml, respectively) was performed according to the follicular fluid (FF) oestradiol‐17β (E) content. The mRNA expression and protein localization was analyzed by reverse transcription‐polymerase chain reaction (RT‐PCR) and immunohistochemistry. FGF1 mRNA expression was relatively high in TI and lower in GC, and without any regulatory change for both tissue compartments during final follicular growth. The FGF1 protein could be predominantly localized in the cytoplasm of GC, in smooth muscle cells of blood vessels, in the rete ovarii, and at a lesser degree in theca cells. FGF2 mRNA in TI increased significantly in large follicles and was low and without any regulatory change in GC. FGF7 mRNA expression was relatively high in TI and very low in GC. For FGF7 in mature follicles a marked staining of the TI and the basal layers of the GC could be demonstrated. The mRNA signal for the FGFR in TI increased significantly with beginning of E production (E > 0.5–5 ng/ml FF) and was without any regulatory change in GC. The mRNA expression of FGFR2IIIb was relatively high in GC and increased significantly during final growth of follicles in contrast to the TI with very low expression. The FGFR2IIIc mRNA expression in TI and GC was relatively high but without any clear change. Our results suggest that FGF growth factor family members are involved in process of folliculogenesis and especially during final growth of the preovulatory (dominant) follicle by stimulation of angiogenesis and GC survival and proliferation. Mol. Reprod. Dev. 67:162–171, 2004. © 2004 Wiley‐Liss, Inc.
Inhibition of bovine sperm–oocyte fusion by the p‐aminophenyl derivative of d‐mannose
Authors: Tanghe Sofie , Van Soom A. , Duchateau L. , de Kruif A.
Published: December 2003

Several steps in the process of mammalian fertilization are mediated by carbohydrates. This study investigated the role of the p‐aminophenyl derivative of d‐mannose (APMP) during bovine fertilization. Inseminating cumulus–oocyte complexes (COCs) in the presence of increasing APMP concentrations resulted in a significant dose‐dependent decrease of the fertilization rate (P < 0.05). No negative effect of 50 mM APMP on total sperm motility and progressive motility was found. Subsequently, the fertilization steps at which this blocking effect could be exerted were investigated, i.e., sperm penetration of the cumulus oophorus, sperm‐zona binding, acrosome reaction, sperm–oolemma binding, and/or sperm–oocyte fusion. Inseminating cumulus‐enclosed and cumulus‐denuded oocytes in the presence of 50 mM APMP significantly decreased the fertilization rate to a comparable minimum level (P < 0.05). There was no significant relationship between the number of spermatozoa bound to the zona pellucida and the APMP concentration, and APMP nor d‐mannosylated bovine serum albumin (BSA) suppressed or stimulated sperm acrosomal status. Inseminating zona‐free oocytes in the presence of 50 mM APMP did not influence sperm–oolemma binding, but significantly inhibited sperm–oocyte fusion (P < 0.05). Preincubating zona‐free oocytes with 200 μg/ml Con A but not with 50 mM APMP inhibited the sperm–oocyte fusion rate to the same extent as when the gametes were simultaneously exposed to 50 mM APMP. These data indicate that the blocking effect of APMP on bovine fertilization is mainly due to an inhibition of sperm–oocyte fusion, probably by specific obstruction of the sperm receptor sites that are responsible for the fusion process. Mol. Reprod. Dev. 67:224–232, 2004. © 2004 Wiley‐Liss, Inc.
Vitrification of pronuclear‐stage mouse embryos on solid surface (SSV) versus in cryotube: Comparison of the effect of equilibration time and different sugars in the vitrification solution
Authors: Bagis H. , Sagirkaya H. , Mercan H. Odaman , Dinnyès A.
Published: December 2003

The cryopreservation of pronuclear‐stage embryos has particular importance in transgenic technology and human assisted reproductive technology (ART). The objective of this study was to improve the efficiency of cryopreservation of pronuclear‐stage mouse embryos. Two vitrification methods (solid surface vitrification (SSV) vs. vitrification in cryotube) have been compared with special emphasis on the effect of the exposure of the embryos to the solutions for various times and the sugar content (trehalose, sucrose, or raffinose) of the vitrification solutions. Pronuclear‐stage embryos were either exposed to 1 M dimethyl sulfoxide (DMSO) + 1 M propylene‐glycol (PG) solution for 2, 5, 10, or 15 min or not exposed to this “equilibration” solution. The vitrification solutions consisted of 2.75 M DMSO and 2.75 M PG in M2 medium supplemented with 1 M trehalose (DPT), 1 M sucrose (DPS), or 1 M raffinose (DPR). In the cryotube method, groups of 15–25 embryos were transferred into a 1.8 ml cryotube containing 30 μl of DPT, DPS, or DPR. After 30 sec, the cryotubes were directly plunged into liquid nitrogen (LN2) and stored for 1 day to 1 month. Vitrified samples were warmed by immersing the cryotubes in a 40°C water bath and then immediately diluted with 300 μl of 0.3 M trehalose, sucrose, or raffinose in M2. In the SSV method, after equilibration 15–20 embryos were exposed to DPT, DPS, or DPR solutions for around 20 sec before being dropped in 2‐μl drops onto a pre‐cooled (−150 to −180°C) metal surface. Vitrified droplets were stored in cryovials in LN2. Warming was performed by transferring the vitrified droplets into 0.3 M solutions of trehalose, sucrose, or raffinose at 37°C, respectively. Results showed that both SSV and cryotube vitrification methods can result in high rates of in vitro blastocyst development (up to 58.3 and 68.5% with DPR, respectively), not statistically different from that of the controls (58.3 and 64.4%). Even without the equilibration step prior to vitrification, relatively high‐survival rates have been achieved, except for the DPS solution. In conclusion, vitrification of pronuclear‐stage mouse embryos can result in high rates of in vitro development to blastocyst, and the use of raffinose in the vitrification solution is advantageous to improve cryosurvival. Mol. Reprod. Dev. 67:186–192, 2004. © 2004 Wiley‐Liss, Inc.
Improved embryo development with decreased apoptosis in blastomeres after the treatment of cloned bovine embryos with β‐mercaptoethanol and hemoglobin
Authors: Park Eul Soon , Hwang Woo Suk , Kang Sung Keun , Lee Byeong Chun , Han Jae Yong , Lim Jeong Mook
Published: December 2003

In preliminary experiments, the treatment of donor somatic cells with β‐mercaptoethanol (ME) or hemoglobin (Hb) improved in vitro‐development of bovine cloned embryos. This study was subsequently evaluated whether the exposure to Hb and/or ME during in vitro‐maturation or embryo culture could further promote the development of embryos cloned with ME‐treated donor cells. A prospective, randomized study was conducted and, embryo development, cell number, and apoptosis in blastocysts were monitored. A significant (P < 0.05) effect was found after the combined treatment of cloned embryos with Hb (1 μg/ml) and ME (10 μM); the development of morulae (53 vs. 35%) was greatly improved, which resulted in enhanced blastocyst formation (38%). However, cell number and apoptosis in blastocysts were predominantly affected by ME rather than Hb; a significant increase in total cell number of blastomeres (142–154 vs. 123 cells/embryo), inner cell mass (ICM) (39–41 vs. 27), and trophectoderm (TE) (103–114 vs. 98), and the ratio of ICM to TE cell number (0.26–0.27 vs. 0.22) was found. Also, the apoptosis index indicating the ratio of apoptotic cell to normal blastomere number was greatly reduced after ME treatments (0.85 vs. 0.056–0.069). When embryos cloned with ME‐treated cells were cultured in Hb + ME‐containing medium, any of the treatments to recipient oocytes before enucleation did not further promote the development. In conclusion, combined treatment of cloned embryos with Hb + ME not only improved in vitro‐development but also decreased blastomere apoptosis. The use of ME‐treated donor cells and the culture of cloned embryos in Hb + ME‐containing medium yielded the optimal results for promoting the production of blastocysts with improved quality. Mol. Reprod. Dev. 67:200–206, 2004. © 2004 Wiley‐Liss, Inc.
Embryonic development of in vitro matured and in vitro fertilized dog oocytes
Authors: Rodrigues Berenice de Ávila , Santos Lucila Carboneiro dos , Rodrigues José Luiz
Published: December 2003

In several studies, early cleavage stage canine embryos have been derived from in vitro fertilized oocytes cultured under various conditions. Despite these results, IVF protocols for canine oocytes have yielded low fertilization rates. In this study, Experiment I compared the effects of tissue culture medium (TCM)‐199 supplemented with either (A) 1 μg/ml estradiol or (B) 20 μg/ml estradiol + 1 μg/ml human somatotropin (hST) on the in vitro nuclear maturation rate of canine oocytes. Meiotic progression to the metaphase I and II (MI/MII) stages at 72 hr of in vitro culture (IVC) was 10.2% (11/108) in medium A versus 14.1% (30/142) in medium B (P = 0.802). In Experiment II, cleavage rate was determined among oocytes recovered from ovaries of bitches at different reproductive stages. Oocytes (n = 888) were retrieved from bitches at the follicular, anestrous, and luteal stages and selected for high morphological quality. Oocytes were matured for 48 hr in TCM‐199 supplemented with 1 μg/ml hST + 20 μg/ml estradiol. Oocytes were in vitro fertilized with fresh canine spermatozoa that had been isolated on a Percoll gradient, and were cultured in synthetic oviduct fluid (SOF) medium with bovine serum albumin (BSA; 4 mg/ml) up to 5 days in 5% CO2 in air at 37°C. A proportion of oocytes (30.6%) with identifiable nuclear material had cytoplasm penetrated or fertilized by sperm. The percentage of oocytes developing into early stage embryos was 10.1% (27/267). Although pronuclear development was observed to be higher for oocytes recovered at the follicular phase, the cleavage rate was similar among oocytes recovered from bitches at the follicular, anestrus, and luteal stages. There was no correlation between the proportion of capacitated or acrosome reacted spermatozoa and pronuclei formation and/or percent cleavage. It was concluded that TCM‐199 supplemented with 1 μg/ml hST and estradiol (20 μg/ml) supports nuclear and cytoplasmic maturation of canine oocytes. In this study, meiotic competence was verified by the in vitro production (IVP) and development of embryos up to the 8 cell‐stage. Furthermore, the results indicate that, under the described conditions and despite the influence of reproductive status of the bitch on the developmental competence of in vitro fertilized oocytes to the pronuclei stage, cleavage was independent of donor's reproductive estrous cycle stage. Mol. Reprod. Dev. 67:215–223, 2004. © 2004 Wiley‐Liss, Inc.