bluuebunny/crossref_metadata_2025_split huggingface dataset:
Earth hummocks (thúfur): new insights to their thermal characteristics and development in eastern Lesotho, southern Africa
Authors: Grab Stefan W. 
Published: April 2005

AbstractThe aspect‐controlled variations in soil freezing within earth hummocks of eastern Lesotho (southern Africa) are analysed. Ground thermal data were measured for an earth hummock from late autumn to early spring in 1995 and 1996, using Tinytalk™ data loggers. During 1995, ground temperatures were recorded at 15 and 20 cm depth on the hummock north, east, south and west aspects, whilst in 1996 temperatures were recorded at 1 cm, 5 cm and 10 cm on the north and south aspects. The data from 1995 indicate that soil freezing commences on the hummock southern aspects and gradually progresses towards the western and northern aspects, whilst the eastern aspect remained unfrozen throughout winter. The data from 1996 indicate that a thick snow cover almost nullifies the temperature differences between the hummock northern and southern aspects. However, given the relative absence of snow during contemporary winters, freeze intensity and duration is longest on the hummock southern and western aspects, which helps explain earth hummock deformation (elongation and coalescence) in a southwesterly direction on slope gradients ≤3°. Copyright © 2005 John Wiley & Sons, Ltd.
Testing a statistical curve‐fitting procedure for quantifying sediment populations within multi‐modal particle‐size distributions
Authors: Leys John , McTainsh Grant , Koen Terry , Mooney Brian , Strong Craig 
Published: April 2005

AbstractThis paper describes a series of tests designed to evaluate the capacity of a personal computer (PC) based statistical curve‐fitting program called MIX to quantify composite populations within multi‐modal particle‐size distributions. Three natural soil samples were analysed by a Coulter Multisizer, and their particle‐size distributions analysed using MIX software to identify the modes, standard deviations and proportions of their composite populations. The particle‐size distributions of the three natural soil samples were then numerically combined in equal proportions using a spreadsheet program to create synthetic particle‐size distributions of known populations. MIX was then tested on the synthetic particle‐size distributions to see if the modes and proportions it identified were similar to those modes and proportions known to characterize the synthetic particle‐size distributions. The main outcome is that MIX can very accurately describe the modal particle size and proportions of the major composite populations within a particle‐size distribution. However MIX has difficulty in identifying small populations (those contributing <10 per cent of a total particle‐size distribution), particularly when they are located in the central sections of particle‐size distributions, overlain by larger populations, or when positioned in the fine tails of distributions. Despite these minor shortcomings, MIX is a valuable tool for the examination and interpretation of particle‐size data. Copyright © 2005 John Wiley & Sons, Ltd.
Provenance of long‐travelled dust determined with ultra‐trace‐element composition: a pilot study with samples from New Zealand glaciers
Authors: Marx Samuel K. , Kamber Balz S. , McGowan Hamish A. 
Published: April 2005

AbstractWe report high‐precision inductively coupled plasma mass spectrometric (ICP‐MS) compositional data for 39 trace elements in a variety of dust deposits, trapped sediments and surface samples from New Zealand and Australia. Dusts collected from the surface of alpine glaciers in the Southern Alps, New Zealand, believed to have undergone long‐distance atmospheric transport from Australia, are recognizable on account of their overabundances of Pb and Cu with respect to typical upper crustal values. Long‐travelled dust from Australia therefore scavenges these and other metals (e.g. Zn, Sb and Cd) from the atmosphere during transport and deposition. Hence, due to anthropogenic pollution, long‐travelled Australian dusts can be recognized by elevated metal contents.The relative abundance of 25 other elements that are not affected by atmospheric pollution, mineral sorting (Zr and Hf) and weathering[sol ]solubility (alkali and earth alkali elements) reflects the geochemistry of the dust source sediment. As a result, we are able to establish the provenance of dust using ultra‐trace‐element chemistry at regional scale. Comparison of long‐travelled dust chemistry with potential Australian sources shows that fits of variable quality are obtained. We propose that the best fitting potential source chemistry most likely represents the major dust source area. A binary mixing model is used to demonstrate that admixture of small quantities of local dust provides an even better fitting dust chemistry for the long‐travelled dusts. Copyright © 2005 John Wiley & Sons, Ltd.
Geomorphic imprint of landslides on alpine river systems, southwest New Zealand
Authors: Korup Oliver 
Published: April 2005

AbstractAn inventory of 846 mass movements, mainly landslides, in two alpine regions of southwest New Zealand was created to explore the geomorphic impacts of slope‐failure processes on river channels and valley floors. In total, 213 (i.e. 27 per cent) of the slope failures descended to valley floors, affecting the geomorphology of trunk channels (catchment area AC > 10 km2) and valley floors in recurring patterns. A nominal classification system is introduced for characterizing (a) the physical contact nature between landslides and river channels, and (b) the resulting geomorphic consequences for drainage. Although landslide area A is useful for estimating the length of channel directly impacted by debris, it does not necessarily predict the direction of fluvial response or type of impact. Dominant persistent geomorphic imprints of bedrock landslides include channel occlusions and landslide dams in South Westland and Fiordland, respectively. Differences in size distribution and geomorphic effects on river systems between the two study regions are attributed to bedrock geology, tectonics and sediment flux. Although South Westland rivers are more frequently affected by landslides, disrupting long‐term effects such as blockage are more persistent in Fiordland. Copyright © 2005 John Wiley & Sons, Ltd.
The Chemical and Structural Nature of Proton Exchange Membrane Fuel Cell Properties
Authors: Hickner M. A. , Pivovar B. S. 
Published: April 2005

AbstractThe chemical and structural (morphological) features of proton exchange membranes are directly tied to their fuel cell relevant transport properties. A large body of research has focused on characterizing the structure or investigating the properties of Nafion® and other proton exchange membranes, but few studies have linked chemical composition to membrane morphology, and resulting transport properties. This paper systematically discusses the key chemical and structural features of proton exchange membranes that impact properties critical for fuel cell applications. We focus our discussion on the fuel cell relevant transport properties of proton conductivity, methanol permeability, water diffusion coefficient, and electro‐osmotic drag coefficient, using evidence from our work and from the literature to illustrate the connection between structure and properties in these materials. It is hoped that this document will serve as a guide to the rational, systematic design of new proton exchange membrane materials with improved properties.
Synthesis and Characterization of Pyridine‐Based Polybenzimidazoles for High Temperature Polymer Electrolyte Membrane Fuel Cell Applications
Authors: Xiao L. , Zhang H. , Jana T. , Scanlon E. , Chen R. , Choe E.‐W. , Ramanathan L. S. , Yu S. , Benicewicz B. C. 
Published: April 2005

AbstractA series of polybenzimidazoles (PBIs) incorporating main chain pyridine groups were synthesized from the pyridine dicarboxylic acids (2,4‐, 2,5‐, 2,6‐ and 3,5‐) and 3,3′,4,4′‐tetraaminobiphenyl, using polyphosphoric acid (PPA) as both solvent and polycondensation reagent. A novel process, termed the PPA process, has been developed to prepare phosphoric acid (PA) doped PBI membranes by direct‐casting of the PPA polymerization solution without isolation or re‐dissolution of the polymers. The subsequent hydrolysis of PPA to PA by moisture absorbed from the atmosphere usually induced a transition from the solution state to a gel‐like state and produced PA‐doped PBI membranes with a desirable suite of physiochemical properties. The polymer structure characterization included inherent viscosity (I.V.) determination as a measurement of polymer molecular weight and thermal stability assessment via thermogravimetric analysis. Physiochemical properties of the doped membrane were studied by measurements of the PA doping level, ionic conductivity and mechanical properties. The resulting pyridine‐based polybenzimidazole membranes displayed high PA doping levels, ranging from 15 to 25 mol of PA per PBI repeat unit, which contributed to their unprecedented high proton conductivities of 0.1 to 0.2 S cm–1 at 160 °C. The mechanical property measurements showed that the pyridine‐based PBI membranes were thermally stable and maintained mechanical integrity even at high PA doping levels. Preliminary fuel cell tests demonstrated the feasibility of the novel pyridine‐based PBI (PPBI) membranes from the PPA process for operating fuel cells at temperatures in excess of 120 °C without any external humidification.
Chemical Modification of Perfluorosulfo‐nated Membranes with Pyrrole for Fuel Cell Application: Preparation, Characteri‐sation and Methanol Transport
Authors: Xu F. , Innocent C. , Bonnet B. , Jones D. J. , Rozière J. 
Published: April 2005

AbstractIn situ chemical polymerisation of pyrrole in Nafion®‐115 membranes produces a composite material that shows a decrease in methanol crossover compared with the non‐modified material, and a good protonic conduction (area resistance of 0.65 Ω cm2). Pyrrole is impregnated from an appropriate solvent, and the choice of oxidising agent (hydrogen peroxide, ammonium peroxodisulfate) provides two types of modified membrane. Membrane characterisation using infrared spectroscopy shows the presence of pyrrole oligomers and polymer, but the proton conductivity is lower than that of the Nafion®‐115 membrane by only a factor 2–3. Methanol transport measurements in 2 mol dm–3 methanol with and without application of an electric field show ca. 30% lower crossover for the pyrrole‐modified membranes. In single cell hydrogen – oxygen fuel cell tests, the pyrrole‐modified Nafion® prepared using hydrogen peroxide oxidant gave higher open circuit voltage and current density, in particular at > 80 °C, than non‐modified Nafion®‐115.
Recent Developments on Proton Conduc‐ting Poly(2,5‐benzimidazole) (ABPBI) Membranes for High Temperature Poly‐mer Electrolyte Membrane Fuel Cells
Authors: Asensio J. A. , Gómez‐Romero P. 
Published: April 2005

AbstractCommercial polybenzimidazole (PBI) membranes impregnated with phosphoric acid have become a serious candidate as electrolytes for high temperature PEMFC. Much research effort has been devoted to the study of this proton conducting membrane.[1, 2] On the other hand, PBI is not the simplest nor the cheapest of this family and many other polybenzimidazoles would also be of great interest in this respect. Among them, poly(2,5‐benzimidazole) (ABPBI) is one of the best choices [3]. ABPBI is easy to polymerize from a single monomer, even without previous purification, it absorbs more acid than PBI in the same bath concentration, and it has the same thermal stability and high proton conductivity at temperatures up to 200 °C. Here we review all the recent developments on the preparation of proton conducting ABPBI membranes, mainly by phosphoric acid impregnation, but also by sulfonation or doping with heteropolyacids to form hybrid organic‐inorganic membranes.
Enhanced susceptibility of S‐100B transgenic mice to neuroinflammation and neuronal dysfunction induced by intracerebroventricular infusion of human β‐amyloid
Authors: Craft Jeffrey M. , Watterson D. Martin , Marks Alexander , Van Eldik Linda J. 
Published: April 2005

AbstractS‐100B is an astrocyte‐derived protein that is increased in focal areas of the brain most severely affected by neuropathological changes in Alzheimer's disease (AD). Cell‐based and clinical studies have implicated S‐100B in progression of a pathologic, glial‐mediated pro‐inflammatory state in the CNS. However, the relationship between S‐100B levels and susceptibility to AD‐relevant neuroinflammation and neuronal dysfunction in vivo has not been determined. To test the hypothesis that overexpression of S‐100B increases vulnerability to β‐amyloid (Aβ)‐induced damage, we used S‐100B‐overexpressing transgenic (Tg) and S‐100B knockout (KO) mice in a mouse model that involves intracerebroventricular infusion of human oligomeric Aβ1‐42. This model mimics many features of AD, including robust neuroinflammation, Aβ plaques, synaptic damage and neuronal loss in the hippocampus. S‐100B Tg, KO, and wild‐type (WT) mice were infused with Aβ for 28 days, sacrificed at 60 days, and hippocampal endpoints analyzed. We found that Tg mice showed increased vulnerability to Aβ‐induced neuropathology relative to either WT or KO mice. Specifically, Tg mice exhibited enhanced glial activation and neuroinflammation, increased nitrotyrosine staining (a marker of glial‐induced neuronal damage), and more pronounced loss of synaptic markers. Interestingly, Tg mice showed no significant differences in Aβ plaque burden compared with WT or KO mice, suggesting that, as in the human situation, the severity of neuronal dysfunction did not correlate with amyloid deposition. Our data are consistent with a model in which S‐100B overexpression in AD enhances glial activation and leads to an augmented neuroinflammatory process that increases the severity of neuropathologic sequelae. © 2005 Wiley‐Liss, Inc.
Trifunctional bispecific antibody–induced tumor cell lysis of squamous cell carcinomas of the upper aerodigestive tract
Authors: Gronau Silke S. , Schmitt Michael , Thess Bernard , Reinhardt Peter , Wiesneth Markus , Schmitt Anita , Riechelmann Herbert 
Published: April 2005

AbstractBackground.The trifunctional bispecific antibody Removab (tbAB) bridges and activates CD3 positive T cells to EpCAM on carcinoma cells and simultaneously binds to an accessory immune‐cell inducing tumor cell lysis. tbAB‐induced tumor cytotoxicity was assessed in an autologous human ex vivo system.Methods.One hundred forty tumor samples and autologous peripheral blood mononuclear cells from a total of 36 patients with head and neck squamous cell carcinomas (HNSCCs) were incubated on a chicken embryo chorioallantois membrane with Removab. Tumor cells coincubated with cisplatin or cell culture medium served as positive and negative controls. Tumor cell lysis was assessed by acridine orange staining or by fluorescence‐activated cell sorting of propidium iodide–marked cells after 24 and 48 hours (T24/T48) coincubation.Results.Coincubation of HNSCC cells with tbAB and autologous peripheral blood mononuclear cells resulted in a 49% ± 6% decrease of viable cells at T24 (p < .005) and in a decrease of 56% ± 8% at T48 (p < .005) compared with the control. The tumor cytotoxicity was similar to that of cisplatin (49% ± 7% decrease at T24 and 49% ± 8% at T48).Conclusion.In an autologous human ex vivo system, the tbAB‐induced tumor cell lysis was comparable to that by cisplatin. © 2005 Wiley Periodicals, Inc. Head Neck 27: XXX–XXX, 2005
High‐throughput protein expression analysis using tissue microarray technology of a large well‐characterised series identifies biologically distinct classes of breast cancer confirming recent cDNA expression analyses
Authors: Abd El‐Rehim Dalia M. , Ball Graham , Pinder Sarah E. , Rakha Emad , Paish Claire , Robertson John F.R. , Macmillan Douglas , Blamey Roger W. , Ellis Ian O. 
Published: April 2005

AbstractRecent studies on gene molecular profiling using cDNA microarray in a relatively small series of breast cancer have identified biologically distinct groups with apparent clinical and prognostic relevance. The validation of such new taxonomies should be confirmed on larger series of cases prior to acceptance in clinical practice. The development of tissue microarray (TMA) technology provides methodology for high‐throughput concomitant analyses of multiple proteins on large numbers of archival tumour samples. In our study, we have used immunohistochemistry techniques applied to TMA preparations of 1,076 cases of invasive breast cancer to study the combined protein expression profiles of a large panel of well‐characterized commercially available biomarkers related to epithelial cell lineage, differentiation, hormone and growth factor receptors and gene products known to be altered in some forms of breast cancer. Using hierarchical clustering methodology, 5 groups with distinct patterns of protein expression were identified. A sixth group of only 4 cases was also identified but deemed too small for further detailed assessment. Further analysis of these clusters was performed using multiple layer perceptron (MLP)‐artificial neural network (ANN) with a back propagation algorithm to identify key biomarkers driving the membership of each group. We have identified 2 large groups by their expression of luminal epithelial cell phenotypic characteristics, hormone receptors positivity, absence of basal epithelial phenotype characteristics and lack of c‐erbB‐2 protein overexpression. Two additional groups were characterized by high c‐erbB‐2 positivity and negative or weak hormone receptors expression but showed differences in MUC1 and E‐cadherin expression. The final group was characterized by strong basal epithelial characteristics, p53 positivity, absent hormone receptors and weak to low luminal epithelial cytokeratin expression. In addition, we have identified significant differences between clusters identified in this series with respect to established prognostic factors including tumour grade, size and histologic tumour type as well as differences in patient outcomes. The different protein expression profiles identified in our study confirm the biologic heterogeneity of breast cancer and demonstrate the clinical relevance of classification in this manner. These observations could form the basis of revision of existing traditional classification systems for breast cancer. © 2005 Wiley‐Liss, Inc.
Association of two mutations in the CHEK2 gene with breast cancer
Authors: Bogdanova Natalia , Enβen‐Dubrowinskaja Natalia , Feshchenko Sergei , Lazjuk Gennady I. , Rogov Yuri I. , Dammann Olaf , Bremer Michael , Karstens Johann H. , Sohn Christof , Dörk Thilo 
Published: April 2005

AbstractThe 1100delC mutation of the cell cycle checkpoint kinase 2 (CHEK2) gene confers an increased risk for breast cancer, but the clinical impact of other CHEK2 gene variants remains unclear. We determined the frequency of two functionally relevant CHEK2 gene mutations, I157T and IVS2+1G > A, in two large series of breast cancer cases and controls from two independent populations. Our first series consisted of a hospital‐based cohort of 996 German breast cancer cases and 486 population controls, and the second series consisted of 424 breast cancer patients and 307 population controls from the Republic of Belarus. The missense substitution I157T was identified in 22/996 cases (2.2%) vs. 3/486 controls (0.6%; OR = 3.6, 95% CI 1.1–12.2, p = 0.044) in the German population and in 24/424 cases (5.7%) vs. 4/307 controls (1.3%; OR = 4.5, 95% CI 1.6–13.2, p = 0.005) in the Byelorussian cohorts. The splicing mutation IVS2+1G > A was infrequent in both populations, being observed in 3/996 German and 4/424 Byelorussian patients (0.3% and 0.9%, respectively) and in 1/486 German controls (0.2%; adjusted OR = 4.0, 95% CI 0.5–30.8, p = 0.273). Heterozygous CHEK2 mutation carriers tended to be diagnosed at an earlier age in both populations, but these differences did not reach statistical significance. Family history of breast cancer did not differ between carriers and noncarriers. Our data indicate that the I157T allele, and possibly the IVS2+1G > A allele, of the CHEK2 gene contribute to inherited breast cancer susceptibility. © 2005 Wiley‐Liss, Inc.
DNA damage uncouples the mitogenic response to IGF‐I in MCF‐7 malignant breast cancer cells by switching the roles of PI3 kinase and p21WAF1/Cip1
Authors: Clark Martin A. , Perks Claire M. , Winters Zoë E. , Holly Jeff M.P. 
Published: April 2005

AbstractIn addition to its mitogenic and survival actions, recent evidence indicates that IGF‐I can enhance DNA repair, implying IGF activity may limit the efficacy of many therapeutic strategies that rely on induction of DNA damage. Although the individual pathways by which DNA damage and IGF‐I act are well understood, the cross‐talk between these signaling events is not well defined. We examined the effects of DNA damage on the IGF‐I response of MCF‐7 breast cancer cells. Cells were exposed to the UV mimetic, 4‐NQO, or the γ‐irradiation mimetic and chemotherapeutic drug, bleomycin; cellular proliferation was assessed by cell counting, tritiated thymidine incorporation and FACS cell cycle analysis. Although IGF‐I acutely suppressed the p53 response to both agents, it subsequently enhanced the chronic increase in p53 and p21WAF1/Cip1, resulting in cell cycle arrest; however, no apoptosis was observed. Use of specific inhibitors demonstrated that PI3 kinase was utilized with p38 MAPK to induce the p53 response to DNA damage, but was also utilized by IGF‐I to diminish the acute p53 response. In addition, p21WAF1/Cip1 was increased by IGF‐I, which has previously been shown to contribute to the mitogenic response. Here we demonstrate that with DNA damage IGF‐I can also enhance the chronic p53‐dependent increase in p21WAF1/Cip1, culminating in growth arrest. Overall, we have shown that PI3 kinase and p21WAF1/Cip1 play dual roles in mediating the mitogenic response to IGF‐I, but these are both switched by cellular DNA damage to mediate a growth arrest. © 2005 Wiley‐Liss, Inc.