bluuebunny/crossref_metadata_2025 huggingface dataset:
Wnt signaling controls radiosensitivity via cyclooxygenase‐2‐mediated Ku expression in head and neck cancer
Authors: Chang Hyo Won , Roh Jong‐Lyel , Jeong Eun‐Jeong , Lee Sang‐wook , Kim Seung‐Whan , Choi Seung‐Ho , Park Sung‐Kyung , Kim Sang Yoon
Published: August 2007

It has been proposed that Wnt signaling pathway may be a key radioprotective mechanism in irradiated cancer cells; however, the specific radioresistance mechanisms remain not to be fully clarified. Here we elucidate a novel signaling pathway of radioresistance in head and neck cancer (HNC) cell lines involving interactions among the Wnt signaling pathway, cyclooxygenase‐2 (COX‐2) and Ku expression. Activation of the Wnt signaling pathway by (2′Z,3′E)‐6‐bromoindirubin‐3′‐oxime (BIO) resulted in β‐catenin cytoplasmic accumulation and translocation to the nucleus, upregulated Ku expression and increased radioresistance in the COX‐2‐expressing HNC cell line. In contrast, Wnt singaling activation by BIO had no effects on Ku expression and radiosensitivity in a HNC cell line negative for COX‐2. Interactions between Wnt singaling and Ku were indirectly regulated by COX‐2. Blockage of COX‐2 signaling led to the suppression of β‐catenin‐induced Ku expression, and to consequent recovery of the radiosensitivity in HNC cells. Our results conclusively suggest that β‐catenin plays a pivotal role in the regulation of Ku expression via the proposed COX‐2 intracellular pathway, thus supporting a novel radioresistance mechanism of HNC. © 2007 Wiley‐Liss, Inc.
Modulation of viability and maturation of human monocyte‐derived dendritic cells by oncolytic adenoviruses
Authors: Schierer Stephan , Hesse Andrea , Müller Ina , Kämpgen Eckhart , Curiel David T. , Schuler Gerold , Steinkasserer Alexander , Nettelbeck Dirk M.
Published: August 2007

Adenoviral oncolysis is a promising new modality for treatment of cancer based on selective viral replication in tumor cells. However, tumor cell killing by adenoviral oncolysis needs to be improved to achieve therapeutic benefit in the clinic. Towards this end, the activation of anti‐tumor immunity by adenoviral oncolysis might constitute a potent mechanism for systemic killing of uninfected tumor cells, thereby effectively complementing direct tumor cell killing by the virus. Knowledge of anti‐tumor immune induction by adenoviral oncolysis, however, is lacking mostly due to species‐specificity of adenovirus replication, which has hampered studies of human oncolytic adenoviruses in animals. We suggest the analysis of interactions of oncolytic adenoviruses with human immune cells as rational basis for the implementation of adenoviral oncolysis‐induced anti‐tumor immune activation. The goal of our study was to investigate how oncolytic adenoviruses affect human dendritic cells (DCs), key regulators of innate and adoptive immunity that are widely investigated as tumor vaccines. We report that melanoma‐directed oncolytic adenoviruses, like replication‐deficient adenoviruses but unlike adenoviruses with unrestricted replication potential, are not toxic to monocyte‐derived immature DCs and do not block DC maturation by external stimuli. Of note, this is in contrast to reports for other viruses/viral vectors and represents a prerequisite for anti‐tumor immune activation by adenoviral oncolysis. Furthermore, we show that these oncolytic adenoviruses alone do not or only partially induce DC maturation. Thus additional signals are required for optimal immune activation. These could be delivered, for example, by inserting immunoregulatory transgenes into the oncolytic adenovirus genome. © 2007 Wiley‐Liss, Inc.
What drives heterogeneity in foreign exchange rate expectations: insights from a new survey
Authors: Dreger Christian , Stadtmann Georg
Published: September 2007

Foreign exchange rate expectations play a central role in virtually all monetary models for the open economy. Therefore, it is extremely important to gain empirical insights into the expectations formation process. In this paper, we use a unique disaggregated data set to model the expectations of the Yen/USD exchange rate of about 50 leading foreign exchange rate professionals. The survey includes not only exchange rate projections but also expectations regarding macroeconomic fundamentals, like GDP growth, inflation, and interest rates. Different expectations of fundamentals can lead to different views of exchange rate dynamics. Using panel models, we are able to confirm the heterogeneity of exchange rate expectations often detected in previous studies. More important, we provide strong evidence regarding the likely source of heterogeneity. In line with forward looking models for the exchange rate, expected fundamentals have a substantial impact on exchange rate expectations, thereby challenging the backward looking evidence from previous studies. However, the heterogeneity in the expectations of macroeconomic fundamentals is not sufficient to explain the heterogeneity in exchange rate expectations. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of anti‐osteopontin monoclonal antibodies: Binding sensitivity to post‐translational modifications
Authors: Kazanecki Christian C. , Kowalski Aaron J. , Ding Tony , Rittling Susan R. , Denhardt David T.
Published: September 2007

Osteopontin (OPN) is primarily a secreted phosphoglycoprotein found in a variety of tissues and body fluids. It has a wide range of reported functions, many of which are affected by the degree of post‐translational modification (PTM) of the protein. These PTMs include phosphorylation, glycosylation, and cross‐linking by transglutaminase. Here we describe the generation of unique monoclonal antibodies raised against recombinant OPN utilizing the OPN knockout mouse. The antibodies exhibit differential binding to OPN produced by different cell lines from the same species, as well to the multiple OPN forms in human urine. Most of the antibodies generated are able to recognize OPN produced by ras‐transformed mouse fibroblasts, however only one antibody recognizes the more phosphorylated protein produced by the differentiating pre‐osteoblast murine cell line MC3T3E1. Using a novel biopanning procedure combining T7 phage gene fragment display and protein G precipitation, we have epitope‐mapped these antibodies. Several of the antibodies bind to regions of the OPN molecule that are phosphorylated, and one binds the region of OPN that is glycosylated. Using phosphorylated and non‐phosphorylated peptides, we show that the binding of two antibodies to the C‐terminal end of OPN is inhibited by phosphorylation of this region. In addition, these two antibodies are able to inhibit cell adhesion to recombinant and weakly modified OPN. The antibodies described herein may prove useful in determining the presence of modifications at specific sites and for identifying structural forms of OPN. Also, the sensitivity of these antibodies to PTMs suggests that caution must be taken when choosing anti‐OPN monoclonal antibodies to detect this highly modified protein. J. Cell. Biochem. 102: 925–935, 2007. © 2007 Wiley‐Liss, Inc.
Small non‐embeddable quasi‐derived designs
Authors: Harada Masaaki , Miyabayashi Hiroki
Published: September 2007

We establish the existence of non‐embeddable quasi‐derived 2‐designs with the parameters (13, 4, 3), (15, 6, 5), and (16, 6, 5). © 2007 Wiley Periodicals, Inc. J Combin Designs 16: 364–372, 2008
Focal adhesion targeting of v‐Crk is essential for FAK phosphorylation and cell migration in mouse embryo fibroblasts deficient src family kinases or p130CAS
Authors: Yeo Myeong Gu , Sung Bong Hwan , Oh Hye Jin , Park Zee Yong , Marcantonio Eugene E. , Song Woo Keun
Published: September 2007

We examined the consequences of v‐Crk expression in mouse embryo fibroblasts deficient Src family kinases or p130CAS. We found that Src kinases are essential for p130CAS/v‐Crk signaling leading to FAK phosphorylation and cell migration in which Src is likely to mediate the focal adhesion targeting of v‐Crk. SYF cells showed only low levels of FAK phosphorylation and cell migration, even in the presence of v‐Crk. Expression of v‐Crk restored migration of p130CAS‐deficient cells to the level of wild‐type cells, most likely through the targeting of v‐Crk to focal adhesions by cSrc. In addition, we identified a new v‐Crk‐interacting protein that mediates v‐Crk signaling in p130CAS‐deficient cells. Using RT‐PCR and caspase cleavage assays, we confirmed that this protein is not p130CAS and is responsible for maintaining v‐Crk/Src signaling and migration in these. These findings suggest that focal adhesion targeting of v‐Crk is essential in v‐Crk‐mediated cellular signaling and that v‐Crk must form a complex with p130CAS or a p130CAS substitute to transduce signaling from the extracellular matrix. J. Cell. Physiol. 214: 604–613, 2008. © 2007 Wiley‐Liss, Inc.
Potential conversion of adult clavicle‐derived chondrocytes into neural lineage cells in vitro
Authors: Li Hong‐Yun , Zhou Xin‐Fu
Published: September 2007

Neural stem cells (NSC) can be isolated from a variety of adult tissues and become a valuable cell source for the repair of peripheral and central nervous diseases. However, their origin and identity remain controversial because of possible de‐differentiation/trans‐differentiation or contaminations by hematopoietic stem cells (HSCs) or mesenchymal stem cells (MSCs). We hypothesize that the commonly used NSC culture medium can induce committed cartilage chondrocytes to de‐differentiate and/or trans‐differentiate into neural cell lineages. Using a biological isolation and purification method with explants culture, we here show that adult rat clavicle cartilage chondrocytes migrate out from tissue blocks, form sphere‐like structures, possess the capability of self‐renewal, express nestin and p75NTR, markers for neural crest progenitors, and differentiate into neurons, glia, and smooth muscle cells. Comparing with adult cartilage, the spherical‐forming neural crest cell‐like cells downregulate the chondrocytic marker genes, including collagen II, collagen X, and sox9, as well as neural‐lineage repressors/silencers REST and coREST, but upregulate a set of well‐defined genes related to neural crest cells and pro‐neural potential. Nerve growth factor (NGF) and glial growth factor (GGF) increase glial and neuronal differentiation, respectively. These results suggest that chondrocytes derived from adult clavicle cartilage can become neural crest stem‐like cells and acquire neuronal phenotypes in vitro. The possible de‐differentiation/trans‐differentiation mechanisms underlying the conversion were discussed. J. Cell. Physiol. 214: 630–644, 2008. © 2007 Wiley‐Liss, Inc.
Old disease, new culprit: Tumor stem cells in cancer
Authors: Lee John T. , Herlyn Meenhard
Published: September 2007

Eloquent studies from hematopoietic systems have provided proof that cancer arises from a tumor stem cell that possesses self‐renewing properties. Until recently, it was believed that this tumor stem cell was unique to leukemic disorders; evidence now suggests that solid tumors also harbor cancer stem cells that are capable of initiating tumor growth in immunodeficient animals with as few as 10 cells. Consequently, the term “tumor‐initiating cell” is now gaining favor within the field. Here, we conceptually discuss the current theories regarding tumor‐initiating cells and their involvement in the development and progression of human malignancies. Special attention is given to laboratory techniques and strategies currently exploited to isolate tumor‐initiating cells from larger populations, including their inherent strengths and weaknesses. The biological relevance of a tumor‐initiating subpopulation is also pondered and arguments regarding their origin are presented. The therapeutic promise of targeting tumor‐initiating cells is certainly eminent and we weigh the advantages of targeting this subpopulation. Lastly, the field of cancer stem cells appears to be well‐placed to make significant strides over the next decade and we discuss potential obstacles that must be negotiated to achieve those objectives. The realization of these goals will undoubtedly further our understanding of this complex disease and should eventually lead to improved therapies in the not‐so‐distant future. J. Cell. Physiol. 213:603–609. © 2007 Wiley‐Liss, Inc.
Osteoarthritis
Authors: Goldring Mary B. , Goldring Steven R.
Published: September 2007

Osteoarthritis (OA) is characterized by degeneration of articular cartilage, limited intraarticular inflammation with synovitis, and changes in peri‐articular and subchondral bone. Multiple factors are involved in the pathogenesis of OA, including mechanical influences, the effects of aging on cartilage matrix composition and structure, and genetic factors. Since the initial stages of OA involve increased cell proliferation and synthesis of matrix proteins, proteinases, growth factors, cytokines, and other inflammatory mediators by chondrocytes, research has focused on the chondrocyte as the cellular mediator of OA pathogenesis. The other cells and tissues of the joint, including the synovium and subchondral bone, also contribute to pathogenesis. The adult articular chondrocyte, which normally maintains the cartilage with a low turnover of matrix constituents, has limited capacity to regenerate the original cartilage matrix architecture. It may attempt to recapitulate phenotypes of early stages of cartilage development, but the precise zonal variations of the original cartilage cannot be replicated. Current pharmacological interventions that address chronic pain are insufficient, and no proven structure‐modifying therapy is available. Cartilage tissue engineering with or without gene therapy is the subject of intense investigation. There are multiple animal models of OA, but there is no single model that faithfully replicates the human disease. This review will focus on questions currently under study that may lead to better understanding of mechanisms of OA pathogenesis and elucidation of effective strategies for therapy, with emphasis on mechanisms that affect the function of chondrocytes and interactions with surrounding tissues. J. Cell. Physiol. 213:626–634. © 2007 Wiley‐Liss, Inc.
Experimental manipulation of ovary activation and gene expression in honey bee (Apis mellifera) queens and workers: testing hypotheses of reproductive regulation
Authors: Thompson Graham J. , Yockey Heather , Lim Julianne , Oldroyd Benjamin P.
Published: September 2007

A fundamental issue in sociobiology is to understand how social insect females regulate their individual reproduction to maximize colony and personal fitness. Although the social cues mediating reproductive output within castes of the honey bees (Apis mellifera) are understood at a basic level, the underlying gene regulatory networks are not. In this study, we investigate the expression of 25 genes whose function suggests a role in the gene networks that regulate ovary activation—a functional determinant of reproductive skew. To this end, we used CO2 narcosis to manipulate ovary activation in queens and workers, and then quantified concomitant changes in gene expression using quantitative polymerase chain reaction. Of the 25 genes studied, ten were differentially expressed between treated and control groups in at least one caste. Two of these genes, a ribosomal protein and a tyramine receptor, were differentially expressed between treatments and controls in both castes. We use the expression pattern of all differentially expressed genes to test hypotheses for the caste‐specific regulation of ovary activation in honey bees. J. Exp. Zool. 307A:600–610, 2007. © 2007 Wiley‐Liss, Inc.
Relationships among household saving, public saving, corporate saving and economic growth in India
Authors: Sinha Dipendra , Sinha Tapen
Published: August 2007

This paper examines the relationship between the growth rates of household saving, public saving, corporate saving and economic growth in India using multivariate Granger causality tests. The conventional wisdom suggests that the causality flows from saving to economic growth. We show that the causality goes in the opposite direction for India. Hence, higher saving is the consequence of higher economic growth and not a cause. Such evidence is consistent with models of habit formation. Copyright © 2007 John Wiley & Sons, Ltd.
Increased hepatic cytochrome P4503A activity decreases the risk of developing steroid‐induced osteonecrosis in a rabbit model
Authors: Masada Toshiaki , Iwakiri Kentaro , Oda Yutaka , Kaneshiro Yasunori , Iwaki Hiroyoshi , Ohashi Hirotsugu , Takaoka Kunio
Published: September 2007

Low hepatic cytochrome P4503A (CYP3A) activities might play an important role for inducing osteonecrosis of the femoral head (ONFH) by corticosteroids. However, the relationship between hepatic CYP3A activity and steroid‐induced ONFH is unknown. We have examined the relationship between hepatic CYP3A activity and the inducibility of ONFH in a rabbit model. Sixty rabbits were divided into three groups. Hepatic CYP3A inducer (phenobarbital, group P; n = 15), inhibitor (itraconazole, group I; n = 15), or saline (group C, n = 30) was administrated for 3 weeks before intramuscular methylprednisolone. In groups P and I, hepatic CYP3A levels were measured by midazolam clearance before treatment (baseline) and before methylprednisolone injection. All animals were sacrificed 3 weeks after methylprednisolone injection and both femurs were harvested and examined histologically for osteonecrosis. Midazolam clearance was significantly increased and decreased, compared with baseline in groups P and I respectively (p < 0.0005, p < 0.002). The incidence of osteonecrosis in group P (33%) was significantly lower than in group I (100%) and group C (83%; p < 0.001 for both). The percentage necrotic area to whole bone marrow area on cross sections in group P (8.2 ± 5.9%) was significantly lower than in group I (69.8 ± 20.8%) and group C (51.5 ± 30.7%; p < 0.005 for both). Hepatic CYP3A activity inversely correlated with the incidence of osteonecrosis and extent of the necrotic area caused by the same dose of corticosteroids, suggesting possible prevention of the steroid‐induced osteonecrosis by reducing steroid dose in poor corticosteroid metabolizers. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:91–95, 2008
Milling performance in desi‐type chickpea (Cicer arietinum L.): effects of genotype, environment and seed size
Authors: Wood Jennifer A , Knights Edmund J , Harden Steven
Published: September 2007

BACKGROUND: Commercial experience suggests that desi chickpea cultivars vary in their milling quality. However, the relative effects of cultivar, growing environment and their interaction are unknown. This study examined the Australian pulse quality method for its effectiveness in comparing the milling quality of breeding lines. The main aims were (1) to determine if there were significant genotypic differences, (2) to quantify the effects of trial, testa content and seed size and (3) to determine if any of the milling quality or seed parameters were correlated. This information would then be used to improve the reliability and efficiency of testing breeding lines.

RESULTS: Large genotypic differences were observed for the milling parameters dehulling efficiency (DE) and splitting yield (SY). The range was greater for SY (16.6%) than for DE (5.8%). Genotype × Trial interactions were significant for DE and SY, while genotype rankings were generally consistent between trials. Seed size and testa content were not significantly associated with either DE or SY. Environmental stresses that affected yield did not appear to influence milling results.

CONCLUSION: The methodology used in this study was able to measure genotypic differences in milling quality. The results suggest that an efficient protocol for testing milling quality of chickpea genotypes would include analysis of at least two sites early in the breeding programme to discard very‐low‐SY genotypes, and further testing in subsequent years including at least one other site to identify high‐SY genotypes if desired. Copyright © 2007 Society of Chemical Industry
Validated liquid chromatographic method for quantitative determination of allicin in garlic powder and tablets
Authors: de Diego Marta , Avello Marcia , Mennickent Sigrid , Fernández Marcos , Fernández Pola
Published: August 2007

In the present study, an RP high performance liquid chromatographic method was developed and validated for the determination of allicin in garlic powder and tablets. Chromatographic separation was carried out on an RP‐18e column (125 mm×4 mm), using a mobile phase, consisting of methanol–water (50:50 v/v), at a flow rate of 0.5 mL/min and UV detection at 220 nm. Ethylparaben was used as the internal standard. The assay was linear for allicin concentrations of 5.0–60.0 μg/mL. The RSD for precision was <6.14%. The accuracy was above 89.11%. The detection and quantification limits were 0.27 and 0.81 μg/mL, respectively. This method was used to quantify allicin in garlic powder samples. The results showed that the method described here is useful for the determination of allicin in garlic powder and tablets.
Development and validation of an HPLC confirmatory method for residue analysis of ten quinolones in tissues of various food‐producing animals, according to the European Union Decision 2002/657/EC
Authors: Christodoulou Eleni A. , Samanidou Victoria F. , Papadoyannis Ioannis N.
Published: August 2007

The aim of this work was to develop an HPLC method for the simultaneous determination of ten quinolones: enoxacin, ofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, sarafloxacin, oxolinic acid, nalidixic acid, and flumequine, in various tissues of food‐producing animals. Separation was achieved on a PerfectSil® Target column (250 mm×4 mm, ODS‐3, 5 μm), by MZ‐Analysentechnik (Germany), at room temperature. The mobile phase consisted of 0.1% TFA–CH3OH–CH3CN and was delivered by a gradient program of 35 min. The detection and quantitation was performed on a photodiode array detector at 275 and 255 nm. Caffeine (7.5 ng/μL) was used as the internal standard (IS). Analytes were isolated from tissue samples by 0.1% methanolic TFA solution. SPE, using LiChrolut RP‐18 cartridges, was applied for further purification. The extraction protocol was optimized and the final recoveries varied between 92.0 and 107.4%. The method was fully validated according to Commission Decision 2002/657/EC. Limits of quantitation for the examined quinolones extracted from each tissue were much lower than the respective Maximum Residue Levels, ranging between 30 and 50 μg/kg for bovine tissue, between 30 and 55 μg/kg for ovine tissue, and between 40 and 50 μg/kg for porcine tissue.
Gel‐free sample preparation for the nanoscale LC‐MS/MS analysis and identification of low‐nanogram protein samples
Authors: Gaspari Marco , Abbonante Vittorio , Cuda Giovanni
Published: August 2007

Protein identification at the low nanogram level could in principle be obtained by most nanoscale LC‐MS/MS systems. Nevertheless, the complex sample preparation procedures generally required in biological applications, and the consequent high risk of sample losses, very often hamper practical achievement of such low levels. In fact, the minimal amount of protein required for the identification from a gel band or spot, in general, largely exceeds the theoretical limit of identification reachable by nanoscale LC‐MS/MS systems. A method for the identification of low levels of purified proteins, allowing limits of identification down to 1 ng when using standard bore, 75 μm id nanoscale LC‐MS/MS systems is here reported. The method comprises an offline two‐step sample cleanup, subsequent to protein digestion, which is designed to minimize sample losses, allows high flexibility in the choice of digestion conditions and delivers a highly purified peptide mixture even from “real world” digestion conditions, thus allowing the subsequent nanoscale LC‐MS/MS analysis to be performed in automated, unattended operation for long series. The method can be applied to the characterization of low levels of affinity purified proteins.
Large vertex symmetric digraphs
Authors: Gómez J.
Published: September 2007

We study the problem of finding large vertex symmetric digraphs with given degree Δ and diameter D. This problem is also called the (Δ,D)‐problem or the degree/diameter problem for vertex symmetric digraphs. It consists of finding vertex symmetric digraphs with the order as large as possible for a given degree and diameter. This paper proposes a new general family of large vertex symmetric digraphs. This new family has order

and provides the best values for asymptotic values of the degree and diameter in general. Moreover, the presented family also provides a large number of new values in the table of the largest known vertex symmetric (Δ,D)‐digraphs. Furthermore, the new family is used to obtain new large vertex symmetric digraphs by means of known compounding techniques. Finally, the table of the largest known vertex symmetric digraphs is provided, where most of the entries correspond to the work presented in this article. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(4), 241–250 2007
The one‐commodity pickup‐and‐delivery traveling salesman problem: Inequalities and algorithms
Authors: Hernández‐Pérez Hipólito , Salazar‐González Juan‐José
Published: September 2007

This article concerns the “One‐commodity Pickup‐and‐Delivery Traveling Salesman Problem” (1‐PDTSP), in which a single vehicle of fixed capacity must either pick up or deliver known amounts of a single commodity to a given list of customers. It is assumed that the product collected from the pickup customers can be supplied to the delivery customers, and that the initial load of the vehicle leaving the depot can be any quantity. The problem is to find a minimum‐cost sequence of the customers in such a way that the vehicle's capacity is never exceeded. This article points out a close connection between the 1‐PDTSP and the classical “Capacitated Vehicle Routing Problem” (CVRP), and it presents new inequalities for the 1‐PDTSP adapted from recent inequalities for the CVRP. These inequalities have been implemented in a branch‐and‐cut framework to solve to optimality the 1‐PDTSP that outperforms a previous algorithm (Hernández‐Pérez and Salazar‐González, Discrete Appl Math 145 (2004), 126–139). Larger instances (with up to 100 customers) are now solved to optimality. The classical “Traveling Salesman Problem with Pickups and Deliveries” (TSPPD) is a particular case of the 1‐PDTSP, and this observation gives an additional motivation for this article. The here‐proposed algorithm for the 1‐PDTSP was able to solve to optimality TSPPD instances with up to 260 customers. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(4), 258–272 2007
Butadiene–isoprene copolymerization with V(acac)3‐MAO. Crystalline and amorphous trans‐1,4 copolymers
Authors: Ricci Giovanni , Zetta Lucia , Alberti Enrica , Motta Tiziano , Canetti Maurizio , Bertini Fabio
Published: September 2007

Butadiene‐isoprene copolymerization with the system V(acac)3‐MAO was examined. Crystalline or amorphous copolymers were obtained depending on isoprene content. Both butadiene and isoprene units exhibit a trans‐1,4 structure and are statistically distributed along the polymer chain. Polymer microstructure, comonomer composition, and distribution along the polymer chain were determined by 13C and 1H NMR analysis. The thermal and X‐ray behaviors of the copolymers were also investigated and compared with results from solid‐state 13C NMR experiments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4635–4646, 2007
Thermoelectric properties of p‐type higher manganese silicide films prepared by solid phase reaction and reactive deposition
Authors: Hou Q. R. , Zhao W. , Chen Y. B. , Liang D. , Feng X. , Zhang H. Y. , He Y. J.
Published: September 2007

Higher manganese silicide (MnSi1.7) films are prepared on silicon and thermally oxidized silicon substrates by reactive deposition and solid phase reaction. By co‐evaporation of manganese and silicon atoms on silicon substrate at about 400 °C, a sharp film‐substrate interface is obtained. For preparation of the films on thermally oxidized silicon substrates by solid phase reaction, the oxygen level in the films is found to be dependent on the deposition rate of silicon. The oxygen and manganese atoms accumulate at the silicide‐Si interface and film‐SiO2 interface, respectively. The sign of the Seebeck coefficient is positive in the temperature range 300 K to 773 K, indicating the p‐type conductivity of the films. The Seebeck coefficient increases with increasing temperature from 294 K to 483 K and is weakly temperature dependent above 483 K. The resistivity increases with temperature near room temperature, reaches a maximum value at about 383 K, and then decreases with further increase of the temperature. The Seebeck coefficient and resistivity at room temperature are about 114 μV/K and 7.37 × 10–3 Ω cm, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of growth temperature of AlGaN buffer layer on the properties of Al0.58Ga0.42N epilayer by NH3‐MBE
Authors: Wang Xiaoyan , Wang Xiaoliang , Wang Baozhu , Xiao Hongling , Liu Hongxin , Wang Junxi , Zeng Yiping , Li Jinmin
Published: September 2007

Al0.58Ga0.42N epilayers are grown by ammonia gas source molecular beam epitaxy (NH3‐MBE) on (0001) sapphire substrate using AlGaN buffer layer. The effects of the buffer layer growth temperature on the properties of Al0.58Ga0.42N epilayer are especially investigated. In‐situ high‐energy electron diffraction (RHEED), double‐crystal X‐ray diffraction (DCXRD), atomic force microscopy (AFM), photoconductivity measurement and cathodoluminescence (CL) are used to characterize the samples. It is found that high growth temperature of AlGaN buffer layer would improve the crystalline quality, surface smoothness, optical quality and uniformity of the Al0.58Ga0.42N epilayer. The likely reason for such improvements is also suggested. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetotransport of holes through an AlAs/GaAs/AlAs resonant tunnelling quantum well with a ferromagnetic Ga1–xMnx As emitter
Authors: Holmberg H. , Lebedeva N. , Novikov S. , Mattila M. , Kuivalainen P. , Du G. , Han X. , Malfait M. , Moshchalkov V. V.
Published: September 2007

We have fabricated magnetic III–V compound semiconductor resonant tunnelling diodes (RTD's) based on a (Ga, Mn)As material system. The RTD's contain a ferromagnetic Mn‐doped emitter, where the Mn‐concentration was chosen on both sides of the metal–insulator (M–I) transition. The measured I –V characteristics show that large magnetoresistance (MR) is not present in non‐magnetic RTD's without the Mn‐doping. In the case of the metallic emitter the observed positive MR is interpreted as an evidence of the magnetization‐dependent tunnelling related to the exchange interaction between the hole spins and the localised spins of the 3d electrons in the ferromagnetic (Ga, Mn)As layer. Especially, the contributions from the spin‐dependent tunnelling described by the Tsu–Esaki model and from the tunnelling anisotropic magnetoresistance, which was found recently in magnetic tunnel diodes, are discussed. The measured large MR in the I –V characteristics of the magnetic RTD's, which have an emitter on the semiconducting side of the M–I transition, is explained by a simple series resistance model for the magnetic emitter, where the conduction in the Anderson localized states below the mobility edge becomes magnetic field‐dependent due to the Mn‐doping. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Deep‐level luminescence at 1.93 eV in GaN prepared by ammonothermal growth
Authors: Fujii Katsushi , Fujimoto Gakuyo , Goto Takenari , Yao Takafumi , Hoshino Naruhiro , Kagamitani Yuji , Ehrentraut Dirk , Fukuda Tsuguo
Published: September 2007

Deep‐level luminescence at 1.93 eV (red luminescence) was observed from GaN grown by the acidic ammonothermal method. Typical deep emission at 2.2 eV (yellow luminescence) was not observed. The intensity decreased linearly with increasing temperature, which is different from the red and yellow luminescence reported thus far. The time decay of the luminescence appeared partially exponential, i.e. with the both possibilities of a simple two‐level transition and donor–acceptor pairs. The origin of the red luminescence is probably different from the previously reported one [J. Appl. Phys. 97, 061301 (2005)]. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hole and electron wave functions in self‐assembled InAs quantum dots: a comparison [phys. stat. sol. (b) 243, No. 15, 3942–3945 (2006)]
Authors: Reuter D. , Kailuweit P. , Roescu R. , Wieck A. D. , Wibbelhoff O. S. , Lorke A. , Zeitler U. , Maan J. C.
Published: August 2007

The assignment of the crystallographic axes for the hole momentum‐space wave function maps shown in Fig. 2 of Reuter et al., phys. stat. sol. (b) 243, 3942 (2006) has been corrected. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study on the partial potential energy surface and formation mechanism of the reactive resonance state of HO + CH4 → H2O + CH3 system
Authors: Lu Xi , Wang Huayang , Cai Zhengting , Feng Dacheng
Published: September 2007

In the course of an extensive investigation aimed at understanding the detailed mechanism of a prototypical polyatomic reaction, several remarkable observations were uncovered. To interpret these findings, we surmise the existence of a reactive resonance in this polyatomic reaction. The concerned system is HO + CH4 → H2O + CH3, of which the partial potential energy surface is constructed by the coupling between vibrational models and reactive coordinates. Then we explain the formation mechanism of the reactive resonance state by the partial potential energy surface. Finally, we estimated the lifetime of the resonance state, and it is about 45fs. The study of the reactive resonance in a polyatomic reaction is more than just an extension from a typical atom + diatom reaction. As shown here, it holds great promise to disentangle the elusive intramolecular vibrational dynamics of the transient collision complex in the critical transition‐state region. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Comparison of MesoHABSIM with two microhabitat models (PHABSIM and HARPHA)
Authors: Parasiewicz P. , Walker J. D.
Published: August 2007

This study demonstrates how using different habitat models can influence the results of instream habitat assessment and conclusions for river management. We used three models for a portion of the Quinebaug River (Connecticut and Massachusetts, USA): a simplistic microhabitat model with univariate habitat‐use criteria and substrate‐based channel index (the Physical Habitat Simulation Model (PHABSIM)); a microhabitat model using multivariate criteria including a wide range of cover attributes (HARPHA); and a mesohabitat model with multivariate habitat‐suitability criteria (MesoHABSIM). The flow‐habitat rating curves produced by each model were compared at two scales: site and study segment. To investigate the impact of model choice on answering questions such as which location or flow provides more habitat, we applied Spearman's correlation of ranks. The relationship between habitat‐suitability predictions and fish presence at the same location was investigated with dedicated fish observations. The study showed that: (1) of the tested models, only MesoHABSIM predictions correlated with fish observations; (2) the variation within microscale models (PHABSIM and HARPHA) was greater than between micro‐and mesoscale models (HARPHA and MesoHABSIM); and (3) simple univariate habitat‐use criteria provided the largest source of discrepancies among the models. We suggest that these differences may lead to erroneous conclusions, especially if flow‐habitat rating curve analysis is considered an endpoint of instream flow study. Copyright © 2007 John Wiley & Sons, Ltd.
Using MesoHABSIM to develop reference habitat template and ecological management scenarios
Authors: Parasiewicz Piotr
Published: August 2007

An important goal in the development of the MesoHABSIM model is its integration into river management frameworks. Here I explain how the model can be used as a backbone for ecological management planning at the catchment scale, and how it may serve in establishing rehabilitation end‐points. Next, I merge the MesoHABSIM model with the target fish community (TFC) approach to develop target habitat conditions and make recommendations for their achievement. By observing the frequency, magnitude and duration of extreme habitat events occurring under natural conditions, one can estimate the critical habitat values and limiting habitat factors leading to environmental stress. This creates a foundation for the developing dynamic flow/habitat augmentation schemes to help prevent human‐induced pulse and press disturbance at the intra‐ and inter‐annual scale. The rules are seasonal and use ‘habitat’ as an ultimate metric rather than flow alone. The final recommendations identify locations with high restoration potential and conservation needs. Copyright © 2007 John Wiley & Sons, Ltd.
A Bayesian predictive two‐stage design for phase II clinical trials
Authors: Sambucini Valeria
Published: August 2007

In this paper, we propose a Bayesian two‐stage design for phase II clinical trials, which represents a predictive version of the single threshold design (STD) recently introduced by Tan and Machin. The STD two‐stage sample sizes are determined specifying a minimum threshold for the posterior probability that the true response rate exceeds a pre‐specified target value and assuming that the observed response rate is slightly higher than the target. Unlike the STD, we do not refer to a fixed experimental outcome, but take into account the uncertainty about future data. In both stages, the design aims to control the probability of getting a large posterior probability that the true response rate exceeds the target value. Such a probability is expressed in terms of prior predictive distributions of the data. The performance of the design is based on the distinction between analysis and design priors, recently introduced in the literature. The properties of the method are studied when all the design parameters vary. Copyright © 2007 John Wiley & Sons, Ltd.
Zertifizierung von Offshore‐Windparks – Erste Erfahrungen
Authors: Faber Torsten , Klose Marcus
Published: September 2007

Die Planung und Errichtung von Offshore‐Windparks ist ein komplexes Aufgabenfeld, an dem eine Vielzahl von Beteiligten aus unterschiedlichen Fachbereichen über mehrere Jahre mitwirkt. Die Errichtungskosten für diese Projekte können im dreistelligen Millionenbereich liegen. Begleitet wird der Prozess im Rahmen der Zertifizierung durch unabhängige Sachverständigenorganisationen wie den Germanischer Lloyd (GL), die ihre Erfahrungen aus der Meerestechnik und den zahlreichen Windparks an Land einbringen, um so die Sicherheit und das “Vieraugenprinzip” zu wahren. Dieser Beitrag erläutert die grundsätzlichen Aspekte der Zertifizierung von Offshore‐Windparks und gibt anhand einiger Beispiele ausgeführter Projekte im europäischen Ausland Einblicke in die Problemstellungen, die sich aus der komplexen Wechselwirkung zwischen Einwirkungen, Tragstruktur und Anlagenverhalten ergeben. Komplettiert wird der Artikel durch Erfahrungen aus Forschungsergebnissen zum Thema Korrosionsschutz und dem Betrieb der Forschungsplattform FINO 1.
Ermüdungsbeanspruchung aus Seegang bei aufgelösten Offshore‐Tragstrukturen
Authors: Schaumann Peter , Böker Cord
Published: September 2007

In diesem Beitrag wird auf Besonderheiten bei der Berechnung und Auslegung von Offshore‐Tragstrukturen in aufgelöster Bauweise (Jackets) eingegangen, wie sie in den letzten Jahren für Offshore‐Windenergieanlagen geplant und gebaut wurden. Zu den Besonderheiten zählen die Sensitivität dieser Tragstrukturen auf die Richtungsverteilung der Wellen in Kurzzeitseegangszuständen sowie die Knotennachgiebigkeiten, die einen Einfluss auf das Gesamttragverhalten und damit auf die Ermüdungsbeanspruchung der Tragstrukturen haben. Es wird gezeigt, wie sich durch die Berücksichtigung dieser beiden Effekte die Ermüdungsbeanspruchung einiger Tragstrukturdetails signifikant reduzieren lässt.
Reduktion der Wanddicken bei Tragtürmen von Windenergieanlagen durch den Einsatz höherfester Stähle
Authors: Ummenhofer Thomas , Weich Imke , Bergers Jennifer , Herion Stefan
Published: September 2007

Bei der Bemessung von Windenergieanlagen wird der Nachweis der Ermüdungsfestigkeit kritischer Kerbdetails, insbesondere von Schweißnähten, maßgebend. Da die in den anzuwendenden Regelwerken aufgeführten Kerbklassen der Schweißnahtdetails unabhängig von der Streckgrenze des Werkstoffs gelten, ist hier der Einsatz höherfester Stähle unwirtschaftlich. Schweißnahtnachbehandlungsverfahren können die Ermüdungsfestigkeit und damit die Lebensdauer dieser Kerbdetails jedoch deutlich erhöhen. Neue Untersuchungen mit Hochfrequenzhämmerverfahren belegen, dass beim Werkstoff S 690 eine Verdopplung der Ermüdungsfestigkeit möglich ist. Am Beispiel einer Schweißverbindung einer Offshore‐Windenergieanlage wird gezeigt, dass bei Anwendung der untersuchten Verfahren bei Einsatz eines S 690 Q die erforderliche Blechdicke auf 45% reduziert werden kann.
Synthesis and preliminary biological evaluation of 3‐[18F]fluoro‐5‐(2‐pyridinylethynyl)benzonitrile as a PET radiotracer for imaging metabotropic glutamate receptor subtype 5
Authors: Wang Ji‐Quan , Tueckmantel Werner , Zhu Aijun , Pellegrino Daniela , Brownell Anna‐Liisa
Published: September 2007

The metabotropic glutamate receptor subtype 5 (mGluR5) has been reported to be implicated in various neurological disorders in the central nervous system.To investigate physiological and pathological functions of mGluR5, noninvasive imaging in a living body with PET technology and an mGluR5‐specific radiotracer is urgently needed. Here, we report the synthesis of 3‐[18F]fluoro‐5‐(2‐pyridinylethynyl)benzonitrile ([18F]FPEB) through a convenient thermal reaction as a highly specific PET radiotracer for mGluR5. The precursor and standard compounds were prepared by a coupling reaction catalyzed by palladium. Radiosynthesis of [18F]FPEB was performed using nitro as a leaving group replaced by [18F]fluoride under conventional heating condition. Biodistribution, metabolite, and microPET studies were performed using Sprague‐Dawley rats. Upto 30 mCi of [18F]FPEB was obtained with a radiochemical yield of 5% and a specific activity of 1900 ± 200 mCi/μmol at the end of syntheses. Biodistribution showed rapid clearance from the blood pool and fast and steady accumulation of radioactivity into the brain. Metabolite studies indicated that only 22% of [18F]FPEB remained in the blood system 10 min after administration, and that a metabolite existed which was much more polar than the parent tracer. MicroPET studies demonstrated that [18F]FPEB accumulated specifically in mGluR5‐rich regions of the brain such as striatum and hippocampus, and that blockade with 2‐methyl‐6‐(2‐phenylethynyl)pyridine (MPEP) and 3‐[(2‐methyl‐1,3‐thiazol‐4‐yl)ethynyl]pyridine (MTEP) substantially reduced the activity uptake in these regions. Selectivity was investigated by blockage with 6‐amino‐N‐cyclohexyl‐N,3‐dimethylthiazolo[3,2‐a]benzimidazole‐2‐caroxamide (YM‐298198), a specific antagonist for mGluR1. [18F]FPEB was prepared conveniently and showed high specificity and selectivity toward mGluR5. It possesses the potential to be used in human studies to evaluate mGluR5 functions in various neurological disorders. Synapse 61:951–961, 2007. © 2007 Wiley‐Liss, Inc.
Ex vivo and in vivo evaluation of (2R,3R)‐5‐[18F]‐fluoroethoxy‐ and fluoropropoxy‐benzovesamicol, as PET radioligands for the vesicular acetylcholine transporter
Authors: Giboureau Nicolas , Emond Patrick , Fulton Roger R. , Henderson David J. , Chalon Sylvie , Garreau Lucette , Roselt Peter , Eberl Stefan , Mavel Sylvie , Bodard Sylvie , Fulham Michael J. , Guilloteau Denis , Kassiou Michael
Published: September 2007

Molecular imaging of the vesicular acetylcholine transporter (VAChT) using positron emission tomography (PET) may provide insights into early diagnosis and better understanding of Alzheimer's disease. We further characterized the VAChT ligand (2R,3R)‐5‐FEOBV (1) and developed new fluoropropoxy analogues. Ex vivo studies of the new nonradiolabeled analogues (2R,3R)‐5‐FPOBV (2) (kD = 0.7 nM) and (2S,3S)‐5‐FPOBV (3) (kD = 8.8 nM) were performed in rat brain and showed an enantioselective inhibition of (−)‐5‐[125I]‐IBVM uptake in striatum, cortex, and hippocampus (e.g., 74% for 2 and only 54% for 3 in the cortex). Radiochemical procedures were developed to produce [18F]1 and [18F]2 as potential imaging agent for the VAChT. The radiochemistry was carried out in a one step procedure, with radiolabeling yields of 17 and 2.6% (range: 1–5.4), respectively, nondecay corrected with good specific activity: 124–338 GBq/μmol. The radiochemical purity was greater than 98%. The biological (ex vivo and in vivo) properties of these radioligands were evaluated in rats and showed a low (less then 0.1% of the injected dose) and homogeneous brain uptake. The in vivo PET study of [18F]2 performed in baboon also revealed rapid defluorination as the main problem. Therefore [18F]1 and [18F]2 appear to be unsuitable for in vivo imaging of the VAChT using PET. Synapse 61:962–970, 2007. © 2007 Wiley‐Liss, Inc.
Rural Employment and Rural-Urban Differences in Employment in Zaire: A Comparative Perspective1
Authors: Shapiro David , Shapiro Sharon
Published: August 2007

This article provides evidence on the extent of de-agrarianization, the nature of rural employment, and rural-urban differences in employment in Zaire. The composition of employment by industry is examined using data from Zaire's 1984 Census. Increased schooling was associated with a greater propensity to be involved in nonagricultural employment. Since 1990, Zaire's chronic economic crisis has become acute and is intertwined with the political crisis resulting from President Mobutu's resistance to popular calls for democratization. In these circumstances, de-agrarianization is effectively put on hold. Nonagricultural employment opportunities have diminished considerably, and an increasing proportion of the country's population is being pushed back to subsistence agriculture.
Facile Hydrogen Evolution Reaction on WO3Nanorods
Authors: Rajeswari Janarthanan , Kishore PilliSatyananda , Viswanathan Balasubramanian , Varadarajan ThirukkallamKanthadai
Published: August 2007

Tungsten trioxide nanorods have been generated by the thermal decomposition (450 °C) of tetrabutylammonium decatungstate. The synthesized tungsten trioxide (WO3) nanorods have been characterized by XRD, Raman, SEM, TEM, HRTEM and cyclic voltammetry. High resolution transmission electron microscopy and X-ray diffraction analysis showed that the synthesized WO3nanorods are crystalline in nature with monoclinic structure. The electrochemical experiments showed that they constitute a better electrocatalytic system for hydrogen evolution reaction in acid medium compared to their bulk counterpart.