bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced high‐dimensional model representation for reliability analysis
Authors: Rao B. N. , Chowdhury Rajib 
Published: August 2008

AbstractThis paper presents a new and alternative computational tool for predicting failure probability of structural/mechanical systems subject to random loads, material properties, and geometry based on high‐dimensional model representation (HDMR) generated from low‐order function components. HDMR is a general set of quantitative model assessment and analysis tools for capturing the high‐dimensional relationships between sets of input and output model variables. It is a very efficient formulation of the system response, if higher‐order variable correlations are weak, allowing the physical model to be captured by the lower‐order terms and facilitating lower‐dimensional approximation of the original high‐dimensional implicit limit state/performance function. When first‐order HDMR approximation of the original high‐dimensional implicit limit state/performance function is not adequate to provide the desired accuracy to the predicted failure probability, this paper presents an enhanced HDMR (eHDMR) method to represent the higher‐order terms of HDMR expansion by expressions similar to the lower‐order ones with monomial multipliers. The accuracy of the HDMR expansion can be significantly improved using preconditioning with a minimal number of additional input–output samples without directly invoking the determination of second‐ and higher‐order terms. The mathematical foundation of eHDMR is presented along with its applicability to approximate the original high‐dimensional implicit limit state/performance function for subsequent reliability analysis, given that conventional methods for reliability analysis are computationally demanding when applied in conjunction with complex finite element models. This study aims to assess how accurately and efficiently the eHDMR approximation technique can capture complex model output uncertainty. The limit state/performance function surrogate is constructed using moving least‐squares interpolation formula by component functions of eHDMR expansion. Once the approximate form of implicit response function is defined, the failure probability can be obtained by statistical simulation. Results of five numerical examples involving elementary mathematical functions and structural/solid‐mechanics problems indicate that the failure probability obtained using the eHDMR approximation method for implicit limit state/performance function, provides significant accuracy when compared with the conventional Monte Carlo method, while requiring fewer original model simulations. Copyright © 2008 John Wiley & Sons, Ltd.
Precise integration methods based on Lagrange piecewise interpolation polynomials
Authors: Wang Meng‐Fu , Au F. T. K. 
Published: August 2008

AbstractThis paper introduces two new types of precise integration methods for dynamic response analysis of structures, namely, the integral formula method and the homogenized initial system method. The applied loading vectors in the two algorithms are simulated by the Lagrange piecewise interpolation polynomials based on the zeros of the first Chebyshev polynomial. Developed on the basis of the integral formula and the Lagrange piecewise interpolation polynomial and combined with the recurrence relationship of some key parameters in the integral computation suggested in this paper with the solving process of linear algebraic equations, the integral formula method has been set up. On the basis of the Lagrange piecewise interpolation polynomial, and transforming the non‐homogenous initial system into the homogeneous dynamic system, the homogenized initial system method without dimensional expanding is presented; this homogenized initial system method avoids the matrix inversion operation and is a general homogenized high‐precision direct integration scheme. The accuracy of the presented time integration schemes is studied and is compared with those of other commonly used schemes; the presented time integration schemes have arbitrary order of accuracy, wider application and are less time consuming. Two numerical examples are also presented to demonstrate the applicability of these new methods. Copyright © 2008 John Wiley & Sons, Ltd.
A class of multiobjective control problems
Authors: de Oliveira V. A. , Silva G. N. , Rojas‐Medar M. A. 
Published: August 2008

AbstractWe introduce the class of MP‐pseudoinvex multiobjective optimal control problems. We show that the concept of MP‐pseudoinvexity is a sufficient condition of optimality and, further, that problems such that every control process satisfying Pontryagin's maximum principle is an optimal process are necessarily MP‐pseudoinvex problems. Moreover, a sub‐class of the MP‐pseudoinvex problems, which we call MP‐invex multiobjective optimal control problems, is defined. We prove that the set of optimal solutions of MP‐invex multiobjective problems coincides with the set of optimal solutions of a related scalar problem. Copyright © 2008 John Wiley & Sons, Ltd.
ESR1 amplification in endometrial carcinomas: hope or hyperbole?
Authors: Tan DSP , Lambros MBK , Marchiò C , Reis‐Filho JS 
Published: August 2008

AbstractThe ESR1 gene maps 6q25 and encodes for oestrogen receptor alpha, which has been shown to play a pivotal role in the development of breast and endometrial cancer. It has recently been reported that oestrogen receptor alpha expression may be driven in some cases by ESR1 gene amplification and that this phenomenon may be an early event in breast and endometrial carcinogenesis. Although copy number gains of 6q have been reported by several groups, their prevalence, association with oestrogen receptor alpha expression, and clinical implications have been a matter of controversy. Here we discuss the key issues regarding the methods employed in the identification of ESR1 amplification, and briefly review the current literature and recent controversies on the subject of ESR1 amplification in endometrial and breast cancers. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
S‐phase kinase protein 2 is an attractive therapeutic target in a subset of diffuse large B‐cell lymphoma
Authors: Uddin S , Hussain A , Ahmed M , Belgaumi A , Al‐Dayel F , Ajarim D , Bavi P , Al‐Kuraya KS 
Published: August 2008

AbstractS‐phase kinase protein 2 (SKP2), an F‐box protein, targets cell‐cycle regulators including cycle‐dependent kinase inhibitor p27KiP1 via ubiquitin‐mediated degradation. SKP2 is frequently overexpressed in a variety of cancer cells and has been implicated in oncogenesis; however, its role in diffuse large B‐cell lymphoma (DLBCL) has not been elucidated. Therefore, we investigated the role of SKP2 and its ubiquitin‐proteasome pathway in a large series (301) of DLBCL patient samples and a panel of DLBCL cell lines. Using immunohistochemistry, SKP2 was detected in 41.6% of DLBCL tumours and was inversely associated with p27Kip1 protein level. The DLBCL subset with high SKP2 and low p27Kip1 showed a strong correlation with the proliferating index marker Ki‐67 (p < 0.0001) and also with the germinal centre phenotype (p = 0.0147). Treatment of DLBCL cell lines with bortezomib or expression of SKP2‐specific siRNA causes down‐regulation of SKP2 and accumulation of p27Kip1, leading to suppression of growth by inducing apoptosis. Furthermore, treatment of DLBCL cells with bortezomib causes apoptosis via involving the mitochondrial pathway and activation of caspases. Finally, treatment of DLBCL cells with bortezomib down‐regulated the expression of XIAP, cIAP1, and survivin. Altogether, these results suggest that SKP2 and the ubiquitin‐proteasome pathway may be a potential target for therapeutic intervention in DLBCL. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Protracted haemangioblastic proliferation and differentiation in von Hippel–Lindau disease
Authors: Shively SB , Beltaifa S , Gehrs B , Duong H , Smith J , Edwards NA , Lonser RR , Raffeld M , Vortmeyer AO 
Published: August 2008

AbstractVon Hippel–Lindau (VHL) disease is caused by germline mutation of the VHL tumour suppressor gene. Patients frequently develop multiple nervous system tumours, denominated haemangioblastomas. Analysis of affected autopsy tissues suggests that tumourigenesis propagates from developmentally arrested, embryonic cells and progresses with consistent architectural, cytological, and molecular sequences similar to haemangioblastic formation and differentiation in the embryo. In this study, we analysed 156 nervous system tumours, 139 of which had been surgically resected from 83 VHL patients. We demonstrate that large tumours consistently contain epithelioid components characteristic of haemangioblastic differentiation in comparison to small tumours that solely display a poorly differentiated, mesenchymal structure. We further show exclusive activation of HIF2α in both small mesenchymal tumours and the mesenchymal component of large tumours, whereas activation of HIF1α is associated with epithelioid structure. We also show that the MIB1 proliferative index is variably increased in the epithelioid component of large tumours, with extramedullary haematopoiesis foci within the epithelioid component at 100%. These data provide compelling evidence that nervous system tumourigenesis in VHL disease represents a protracted process of haemangioblastic proliferation and differentiation that parallels haemangioblastic formation and differentiation in the embryo. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Clinical and biological significance of CXCL12 and CXCR4 expression in adult testes and germ cell tumours of adults and adolescents
Authors: Gilbert DC , Chandler I , McIntyre A , Goddard NC , Gabe R , Huddart RA , Shipley J 
Published: August 2008

AbstractInteraction between the chemokine CXCL12 (SDF1) and the G‐protein coupled receptor CXCR4 is responsible for the maintenance of adult stem cell niches and is known to play an important role in utero in the migration of primordial germ cells. We demonstrate expression of CXCL12 by Sertoli cells and confirm CXCR4 expression by the germ cell population of the adult human testes. CXCR4 is also known to mediate organ‐specific patterns of metastases in a range of common cancers. We identify consistent expression of CXCR4 mRNA and protein in testicular germ cell tumours (TGCT) that accounts for their patterns of relapse in sites of known CXCL12 expression. Extragonadal primary germ cell tumours express CXCR4 and their sites of occurrence are coincident with areas of known CXCL12 expression in utero. We show that CXCL12 stimulates the invasive migration of a TGCT cell line in vitro in a CXCR4‐dependent fashion and activates ERK. Furthermore, we demonstrate that expression of CXCL12 in stage I non‐seminomas is significantly associated with organ‐confined disease post‐orchidectomy and reduced risk of relapse (p = 0.003). This may be through the loss of CXCL12 gradients that might otherwise attract cells away from the primary tumour. We propose CXCL12 expression as a potential predictor of subsequent relapse that could lead to avoiding unnecessary treatment and associated late toxicities. Our observations support a role for CXCL12/CXCR4 in the adult germ cell population and demonstrate pathological function in germ cell tumour development and metastasis that may have clinical utility. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
A new crosslinked protein fiber from gliadin and the effect of crosslinking parameters on its mechanical properties and water stability
Authors: Li Ying , Reddy Narendra , Yang Yiqi 
Published: August 2008

AbstractBACKGROUND: Although several cereal proteins have been used to develop fibers and films, it has not been possible to obtain protein materials with good mechanical properties and water stability, even after crosslinking. Previously, high concentrations of glutaraldehyde were used to improve the mechanical properties of protein fibers but the effect of crosslinking conditions on the properties of the crosslinked materials has not been studied in detail.RESULTS: Low concentrations of glutaraldehyde can be used to improve the mechanical properties and water stability of gliadin fibers. Quantitative relationships that can predict the breaking tenacity of the fibers at various crosslinking conditions are developed. Glutaraldehyde crosslinking is more resistant to hydrolysis in neutral pH than under acidic conditions in terms of increasing and retaining the breaking tenacity. The crosslinked fibers show improved resistance to hydrolysis over poly(lactic acid) fibers in aqueous dispersions at pH = 4 and 7 at 50 and 90 °C, respectively.CONCLUSIONS: This study shows that low concentrations of glutaraldehyde can impart excellent mechanical properties to gliadin fibers. The quantitative relationships developed can be used to select the crosslinking conditions such low glutaraldehyde concentration and high temperature or vice versa to obtain the desired improvement in mechanical properties or water stability. Copyright © 2008 Society of Chemical Industry
Fabrication of protein‐doped PLA composite nanofibrous scaffolds for tissue engineering
Authors: Yuan Jiang , Shen Jian , Kang Inn‐Kyu 
Published: August 2008

AbstractBACKGROUND: Electrospinning is known as a novel fabrication method to form nanofibrous scaffolds for tissue‐engineering application. Previously, many natural biopolymers of protein have been electrospun. However, keratin has not attracted enough attention. In this study, keratin and gelatin were co‐electrospun with polylactide (PLA), respectively.RESULTS: The resulting nanofibers were characterized by a field emission scanning electron microscope (FE‐SEM), an attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR), and an electron spectroscopy for chemical analysis (ESCA). The biodegradation of mats in the presence of trypsin solution was studied. Cell attachment experiments showed that NIH 3T3 cells adhered more and spread better onto the PLA/keratin and PLA/gelatin nanofibrous mats than that onto the blank PLA mats. MTT and BrdU assay showed that PLA/keratin and PLA/gelatin nanofibrous mats could both accelerate the viability and proliferation of fibroblast cells as compared to PLA nanofibrous mats.CONCLUSION: The present study suggests that the introduction of gelatin and keratin can both improve cell‐material interaction, especially, the former is more effective. Copyright © 2008 Society of Chemical Industry
Effect of electric potential and coulombic interactions on electrospinning nanofiber distribution
Authors: Zhang Jian‐Feng , Yang Dong‐Zhi , Nie Jun 
Published: August 2008

AbstractBACKGROUND: Electrospinning is a versatile method to process solutions or melts into micro‐ or nanofibers. Several mathematic models for electrospinning have been established, focused mostly on the fiber formation process, but seldom on the distribution of collected fibers by considering the electric field effect.RESULTS: A method based on electric potential and coulombic interactions was developed to simulate the distribution of electrospun fibers. Two different types of electric field were investigated; and the process was interpreted by schematic diagrams and physical equations. In this case, the simulation analysis based on idealized models is convenient to understand the effect of the distorted electric field induced by different types of collectors.CONCLUSION: The effects of electric potential and Coulombic interactions are the decisive factors in the collect process. The mathematic model can indeed predict the distribution of electrospun fibers. Copyright © 2008 Society of Chemical Industry
A “plug and play” polymer through biocomplementary hydrogen bonding
Authors: Cheng Chih‐Chia , Huang Chih‐Feng , Yen Ying‐Chieh , Chang Feng‐Chih 
Published: August 2008

AbstractThis article describes a DNA‐like polymer that exhibits the ability to self‐assemble through hydrogen bonding. We synthesized poly[1‐(4‐vinylbenzyl)thymine] (PVBT) and 9‐hexadecyladenine (A‐C16) through an atom transfer radical polymerization (ATRP) and alkylation, respectively. Biocomplementary PVBT/A‐C16 hierarchical supramolecular complexes formed in dilute DMSO solution through nucleobase recognition, that is, hydrogen bonding interactions between the thymine (T) groups of PVBT and the adenine (A) group of A‐C16; evidence for this molecular recognition was also gained from dynamic light scattering studies. 1H NMR titration studies in CDCl3 showed that T–A complexes formed rapidly on the NMR time scale with high association constants (up to 534 M−1). Moreover, FTIR spectroscopic, differential scanning calorimetry, wide‐angle X‐ray diffraction, and small‐angle X‐ray scattering analyses provided further details into the nature of the self‐assembly of these systems. In the bulk state, these complexes self‐assemble into well‐ordered lamellar structures; the changing d‐spacing distance (ranging from 4.98 to 2.32 nm) at different A‐C16 loadings reveals that the molecular structures of the PVBT/A‐C16 complexes are readily tailored. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6416–6424, 2008
Synthesis and characterization of amphiphilic block copolymer of polyphosphoester and poly(L‐lactic acid)
Authors: Yang Xian‐Zhu , Wang Yu‐Cai , Tang Ling‐Yan , Xia Hai , Wang Jun 
Published: August 2008

AbstractAliphatic polyesters and polyphosphoesters (PPEs) have received much interest in medical applications due to their favorable biocompatibility and biodegradability. In this work, novel amphiphilic triblock copolymers of PPE and poly(L‐lactic acid) (PLLA) with various compositions were synthesized and characterized. The blocky structure was confirmed by GPC analyses. These triblock copolymers formed micelles composed of hydrophobic PLLA core and hydrophilic PPE shell in aqueous solution. Critical micellization concentrations of these triblock copolymers were related to the polymer compositions. Incubation of micelles at neutral pH followed by GPC analyses revealed that these polymer micelles were hydrolysized and resulted in decreased molecular weights and small oligomers, whereas its degradation in basic and acid mediums was accelerated. MTT assay also demonstrated the biocompatibility against HEK293 cells. These biodegradable polymers are potential as drug carriers for biomedical application. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6425–6434, 2008
Enzymatic and chemical hydrolysis of poly(ethylene terephthalate) fabrics
Authors: Brueckner Tina , Eberl Anita , Heumann Sonja , Rabe Maike , Guebitz Georg M. 
Published: August 2008

AbstractAlkaline and enzymatic hydrolyzes of poly(ethylene terephthalate) fabrics (PET) were mechanistically compared based on released degradation products (HPLC‐UV‐RI) and changes in surface properties [hydrophilicity, cationic dyeing, X‐ray photoelectron spectroscopy (XPS)]. Enzymatic hydrolysis led to an increase in the amount of hydroxyl and carboxyl groups on the surface resulting in an enhanced water absorption and dyeability. Enzymes partially adsorbed to PET fabrics during hydrolysis were completely removed by subsequent extraction according to XPS analysis. In contrast to the enzyme treatment, alkaline hydrolysis did not lead to an increase of hydroxyl and acid groups according to XPS while both treatments caused a substantial increase in hydrophilicity and were more effective on amorphous fibers. Alkaline hydrolysis led to a greater increase in the K/S value after cationic dyeing due to enlarged surface area. Consequently, ESEM‐images demonstrated that alkaline treatment drastically affected the surface morphology of the polymer resulting in crater‐like structures of the fibers, whereas after enzymatic treatment the morphology of the fibers remained unchanged. To reach similar benefits in hydrophilicity, drastically higher amounts of degradation products were released during alkaline hydrolysis as also indicated by >6% weight loss compared to <1% after enzyme treatment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6435–6443, 2008
Synthesis of various stimuli‐responsive gradient copolymers by living cationic polymerization and their thermally or solvent induced association behavior
Authors: Seno Ken‐Ichi , Tsujimoto Itsuko , Kanaoka Shokyoku , Aoshima Sadahito 
Published: August 2008

AbstractStimuli‐responsive gradient copolymers, composed of various monomers, were synthesized by living cationic polymerization in the presence of base. The monomers included thermosensitive 2‐ethoxyethyl vinyl ether (EOVE) and 2‐methoxyethyl vinyl ether (MOVE), hydrophobic isobutyl vinyl ether (IBVE) and 2‐phenoxyethyl vinyl ether (PhOVE), crystalline octadecyl vinyl ether (ODVE), and hydrophilic 2‐hydroxyethyl vinyl ether (HOVE). The synthesis of gradient copolymers was conducted using a semibatch reaction method. Living cationic polymerization of the first monomer was initiated using a conventional syringe technique, followed by an immediate and continuous addition of a second monomer using a syringe pump at regulated feed rates. This simple method permitted precise control of the sequence distribution of gradient copolymers, even for a pair of monomers with very different relative monomer reactivities. The stimuli‐responsive gradient, block and random copolymers exhibited different self‐association behavior. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6444–6454, 2008
Preparation of flexible and transparent polylactic acids films by crystallization manipulation
Authors: Lertworasirikul Amornrat , Arikawa Yuuya , Kaneko Tatsuo , Kida Toshiyuki , Akashi Mitsuru 
Published: August 2008

AbstractHighly flexible and transparent polylactic acids (PLAs) films were successfully prepared by manipulating their crystallization. The semicrystalline poly(L‐lactic acid) (L) was blended with a noncrystalline poly(DL‐lactic acid) (DL) together with diglycerol tetraacetate (DGTA). Optimal DGTA content to plasticize PLAs was about 17%. Addition of DL hindered the crystallization of the films. Tensile strengths of the films having DL content more than 5% were about 10 MPa while the elongations at break were boosted as DL content increased. Films having L/DL ratio of 50/50 showed elongations at break of 270%. Stretch ability and clarity of films containing 15–50% DL were fair although they were subjected to annealing at 60 °C for 1 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6489–6495, 2008