bluuebunny/crossref_metadata_2025_split huggingface dataset:
XMM‐Newton: The next decade for cool star research
Authors: Schmitt J.H.M.M. 
Published: February 2008

AbstractIn this article I will highlight selected results from XMM‐Newton observations of stellar coronae, emphasizing the specific XMM‐Newton capabilities in terms of high‐resolution spectroscopy, its long‐look capability and its optical monitor. I will focus on results on “normal”, cool stars and present science areas hitherto largely unexploired by XMM‐Newton. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Results and perspectives of young stellar object long look programs
Authors: Sciortino S. 
Published: February 2008

AbstractBoth Chandra and XMM‐Newton have performed long look programs for studying the YSO physics. I will discuss recent results on the controversial issue of Class 0 YSO X‐ray emission, the observational evidence of magnetic funnels interconnecting the YSO with its circumstellar disk and the Fe 6.4 keV fluorescent line emission and its origin. While recent results of the XMM‐Newton DROXO program challenge the “standard” interpretation of the Fe 6.4 kev line origin as due to photoionized fluorescing disk material, the discovery of X‐ray excited Ne 12.81 μ m line is a clear evidence of the interaction between X‐rays and disk material. Future long look observations with XMM‐Newton are required to clarify the X‐ray effects on YSO disk. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton: The next decade
Authors: Schartel N. 
Published: February 2008

AbstractSome key numbers about the XMM‐Newton users, usage of the mission and the scientific outcome are provided. The background for selecting the topic, the preparation work, the organization and the corresponding committees are briefly described. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton operations beyond the 10‐year design lifetime
Authors: Parmar A.N. , Heger D. , Metcalfe L. , Muñoz R. , Schartel N. 
Published: February 2008

AbstractIn preparation for XMM‐Newton operations beyond the 10‐year design lifetime ESA instigated an independent review of all aspects of the mission. Unsurprisingly, the review found that the scientific interest in extending the mission is very high and likely to remain so in the foreseeable future. Most importantly, all the elements of the XMM‐Newton mission were found to be stable and trouble free with sufficient consumables and life‐limited items to allow operations of the mission until at least 2018. The review endorsed the proposal to combine elements of the Flight Control Team with those from INTEGRAL and remove real‐time instrument monitoring from ESAC in order to reduce costs and improve efficiency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toward a biobased economy: examples from the UK
Authors: Jenkins Tom 
Published: February 2008

AbstractThe security and cost of fossil reserves and the negative environmental impacts associated with their use are driving the replacement of our current economy, based on fossil reserves, with a new economy, based on renewable biological resources. The emerging bioeconomy offers a sustainable alternative for the production of energy, chemicals, materials and transportation fuels from biorenewable feedstocks. In the bioeconomy, biorefineries will process biomass into a range of value‐added bioproducts. This is analogous to today's oil refineries which produce multiple fuels and products from mineral oil. Worldwide progress in biorefinery development is occurring rapidly with a number of countries providing well‐funded public/private programmes to help ensure development of a competitive bioeconomy. The Bioscience for Business Knowledge Transfer Network (KTN) has highlighted the current lack of a coordinated UK initiative in this area and is establishing a major new industry‐led programme, the Integrated Biorefining Technologies Initiative (IBTI). IBTI is a product development partnership consisting of leading industries working together and with the UK Government to define the research and development and demonstration needs of biorefineries for industrial production. Strategic problem‐solving research will focus on diverse renewable raw material feedstocks and the essential conversion technologies necessary to realize their full economic potential. IBTI will help to underpin UK progress in developing a competitive bioeconomy that will be a key to sustainable industrial progress and economic growth in the coming century. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Triple‐helical peptides: An approach to collagen conformation, stability, and self‐association
Authors: Brodsky Barbara , Thiagarajan Geetha , Madhan Balaraman , Kar Karunakar 
Published: February 2008

AbstractPeptides have been an integral part of the collagen triple‐helix structure story, and have continued to serve as useful models for biophysical studies and for establishing biologically important sequence‐structure‐function relationships. High resolution structures of triple‐helical peptides have confirmed the basic Ramachandran triple‐helix model and provided new insights into the hydration, hydrogen bonding, and sequence dependent helical parameters in collagen. The dependence of collagen triple‐helix stability on the residues in its (Gly‐X‐Y)n repeating sequence has been investigated by measuring melting temperatures of host‐guest peptides and an on‐line collagen stability calculator is now available. Although the presence of Gly as every third residue is essential for an undistorted structure, interruptions in the repeating (Gly‐X‐Y)n amino acid sequence pattern are found in the triple‐helical domains of all nonfibrillar collagens, and are likely to play a role in collagen binding and degradation. Peptide models indicate that small interruptions can be incorporated into a rod‐like triple‐helix with a highly localized effect, which perturbs hydrogen bonds and places the standard triple‐helices on both ends out of register. In contrast to natural interruptions, missense mutations which replace one Gly in a triple‐helix domain by a larger residue have pathological consequences, and studies on peptides containing such Gly substitutions clarify their effect on conformation, stability, and folding. Recent studies suggest peptides may also be useful in defining the basic principles of collagen self‐association to the supramolecular structures found in tissues. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 345–353, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Roles of β‐turns in protein folding: From peptide models to protein engineering
Authors: Marcelino Anna Marie C. , Gierasch Lila M. 
Published: February 2008

AbstractReverse turns are a major class of protein secondary structure; they represent sites of chain reversal and thus sites where the globular character of a protein is created. It has been speculated for many years that turns may nucleate the formation of structure in protein folding, as their propensity to occur will favor the approximation of their flanking regions and their general tendency to be hydrophilic will favor their disposition at the solvent‐accessible surface. Reverse turns are local features, and it is therefore not surprising that their structural properties have been extensively studied using peptide models. In this article, we review research on peptide models of turns to test the hypothesis that the propensities of turns to form in short peptides will relate to the roles of corresponding sequences in protein folding. Turns with significant stability as isolated entities should actively promote the folding of a protein, and by contrast, turn sequences that merely allow the chain to adopt conformations required for chain reversal are predicted to be passive in the folding mechanism. We discuss results of protein engineering studies of the roles of turn residues in folding mechanisms. Factors that correlate with the importance of turns in folding indeed include their intrinsic stability, as well as their topological context and their participation in hydrophobic networks within the protein's structure. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 380–391, 2008.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Physiologic mechanisms of sequential products synthesis in 1,3‐propanediol fed‐batch fermentation by Klebsiella pneumoniae
Authors: Zheng Zong‐Ming , Xu Yun‐Zhen , Liu Hong‐Juan , Guo Ni‐Ni , Cai Zhong‐Zhen , Liu De‐Hua 
Published: February 2008

AbstractThe glycerol fed‐batch fermentation by Klebsiella pneumoniae CGMCC 1.6366 exhibited the sequential synthesis of products, including acetate, 1,3‐propanediol (1,3‐PD), 2,3‐butanediol, ethanol, succinate, and lactate. The dominant flux distribution was shifted from acetate formation to 1,3‐PD formation in early‐ exponential growth phase and then to lactate synthesis in late‐exponential growth phase. The underlying physiological mechanism of the above observations has been investigated via the related enzymes, nucleotide, and intermediary metabolites analysis. The carbon flow shift is dictated by the intrinsic physiological state and enzymatic activity regulation. Especially, the internal redox state could serve as a rate‐controlling factor for 1,3‐PD production. The q1,3‐PD formation was the combined outcomes of regulations of glycerol dehydratase activity and internal redox balancing. The qethanol/qacetate ratios demonstrated the flexible adaptation mechanism of K. pneumoniae preferring ATP generation in early‐exponential growth phase. A low PEP to pyruvate ratio corresponded LDH activity increase, leading to lactate accumulation in stationary phase. Biotechnol. Bioeng. 2008;100: 923–932. © 2008 Wiley Periodicals, Inc.
Optimization of sylvite transformation into arcanite using experimental design methodology
Authors: Fezei R. , Hammi H. , M'nif A. 
Published: February 2008

AbstractThis study is an application of the experimental design methodology for optimizing a potassium sulfate synthesis reaction. The latter is a two‐stage reaction through an intermediate product (Schoenite: K2SO4.MgSO4·6H2O). To determine optimal experimental conditions of the first stage, we have conducted a fractional factorial design and a central composite one. The optimal conditions of the second stage were determined only by means of a fractional factorial design. Several physico‐chemical techniques were used to implement this study, namely potentiometry, complexometry, gravimetry and X‐ray diffraction. This work has showed that this double decomposition reaction, when performed under the determined optimal conditions, gives good quality potassium sulfate (purity more than 95%) with a maximal yield. Copyright © 2008 John Wiley & Sons, Ltd.
Resolving the sign ambiguity in the singular value decomposition
Authors: Bro R. , Acar E. , Kolda Tamara G. 
Published: February 2008

AbstractMany modern data analysis methods involve computing a matrix singular value decomposition (SVD) or eigenvalue decomposition (EVD). Principal component analysis is the time‐honored example, but more recent applications include latent semantic indexing (LSI), hypertext induced topic selection (HITS), clustering, classification, etc. Though the SVD and EVD are well established and can be computed via state‐of‐the‐art algorithms, it is not commonly mentioned that there is an intrinsic sign indeterminacy that can significantly impact the conclusions and interpretations drawn from their results. Here we provide a solution to the sign ambiguity problem and show how it leads to more sensible solutions. Copyright © 2008 John Wiley & Sons, Ltd.
Chemistry of Bridging Phosphanes: CuI Dimers Bearing 2,5‐Bis(2‐pyridyl)phosphole Ligands
Authors: Nohra Brigitte , Rodriguez‐Sanz Elena , Lescop Christophe , Réau Régis 
Published: February 2008

AbstractBis(2‐pyridyl)phosphole 1 reacted with CuI sources giving rise to dicationic or neutral dimers 2,3. In these derivatives, 1 acts as a 1κN:1,2κP:2κN donor with a symmetrically bridging P centre. X‐ray diffraction studies of these species revealed no constraint due to the unusual coordination mode of the P donor. A comparative study with a monometallic CuI complex in which 1 acts as a P,N chelate is presented. The acetonitrile ligands of the dicationic complex 2 can be displaced by a variety of donors. Bipyridine (bipy) acts as a chelating donor, while 1,1′‐bis(diphenylphosphino)methane (dppm) and bis(2‐pyridyl)phosphole 1 behave as bridging ligands. By using dppm and 1, the complexes arising from the stepwise displacement of the acetonitrile ligands of complex 2 can be isolated. X‐ray diffraction studies performed on these novel complexes revealed that the P centre can easily switch from a bridging to a semibridging coordination mode. Of particular interest, within the same unit cell, complexes with P centres exhibiting bridging and semibridging coordination modes are observed. This switching can be induced by weak effects such as a different conformation of the incoming ligand. CuI dimers assembled by 1 are air‐stable derivatives that are not water sensitive. Hydrolysis of the PF6− counterion occurs under drastic conditions and results in the formation of a PO2F2 fragment coordinated to a CuI–1 fragment.
Herstellen von Emulsionen in einfachen und modifizierten Lochblenden: Einfluss der Geometrie auf die Effizienz der Zerkleinerung und Folgen für die Maßstabsvergrößerung
Authors: Aguilar F. , Köhler K. , Schubert H. , Schuchmann H. P. 
Published: February 2008

AbstractDas Hochdruckhomogenisieren ist ein in der Technik weit verbreitetes Homogenisierverfahren. Tropfen einer Rohemulsion („Premix”︁) werden in der Homogenisierdüse aufgrund von Scher‐ oder Dehnspannungen sowie durch Trägheitskräfte vor allem in turbulenter oder in kavitierender Strömung zerkleinert. Die Geometrie der Homogenisierdüse sowie das Stoffsystem bestimmen wie die Tropfen zerkleinert werden (Zerkleinerungsmechanismus) und wie effizient dabei die eingebrachte Energie umgesetzt wird. Die Mechanismen der Zerkleinerung von Öltropfen unterschiedlicher Viskositäten in einfachen (geraden) Lochblenden unterschiedlicher Geometrie sind Inhalt des ersten Teils der im Rahmen dieses Beitrages dargestellten Untersuchungen. Diese Ergebnisse sind auch Basis für eine Maßstabvergrößerung, die durch ein Scale‐ bzw. Numbering up gelöst werden kann. Im zweiten Teil dieses Beitrages werden Ergebnisse zu konstruktiven Begrenzungen einer geometrischen Maßstabsvergrößerung und Randbedingungen für ein Numbering up aufgezeigt.
Indirect Determination of Trace Copper(II) by Adsorptive Stripping Voltammetry with Zincon at a Carbon Paste Electrode
Authors: Taher Mohammad Ali , Esfandyarpour Mohammad , Abbasi Shahryar , Mohadesi Alireza 
Published: February 2008

AbstractTraces of copper(II) can be determined by adsorptive stripping voltammetry using 2‐carboxy‐2′‐hydroxy‐5′‐sulfoformazyl benzene (Zincon) as complex forming reagent. First in phosphate buffer pH 6.4, copper(II)‐Zincon complex was adsorbed on carbon paste electrode (CPE) with an accumulation potential of 0.6 V. Following this, adsorbed complex was oxidized and detected by differential pulse voltammetric (DPV) scan from 0.6 to 1.0 V. The effective parameters in sensor response were examined. The detection limit (DL) of copper(II) was 1.1 μg/L and relative standard deviations (RSDs) for 10 and 200 μg/L Cu(II) were 1.81 and 1.03%, respectively. The calibration curve was linear for 2–220 μg/L copper(II). The resulting CPE does not use mercury and therefore, has a positive environmental benefit. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amount of copper in water and human hair samples.
Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio
Authors: Foley Joe P. , Hong Mei , Polinko Michelle A. , Pascoe Robert J. , Ahuja Eric S. 
Published: February 2008

AbstractThe effect of the phase ratio on the electrophoretic and chromatographic properties of unilamellar vesicles comprised of cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) was investigated in EKC. The surfactant concentration of the vesicles was 0.9, 1.2, 1.5, and 1.8% w/v, with a mole ratio of 1:3.66 (CTAB/SOS). Results were compared to those obtained using SDS micelles at concentrations of 1.0% (w/v, 35 mM) and 1.5% (52 mM). The CTAB/SOS vesicles (0.9–1.8% w/v) provided a significantly larger elution range (5.7 ≤ tves/t0 ≤ 8.7) and greater hydrophobic (methylene) selectivity (2.8 ≤ αCH2 ≤ 3.1) than SDS micelles (3.1 ≤ tmc/t0 ≤ 3.3; αCH2 = 2.2). Whereas the larger elution range can be attributed to the 25% reduction in EOF due to the interaction of unaggregated CTAB cations and the negatively charged capillary wall, the higher methylene selectivity is likely due to the lower concentration of water expected in the CTAB/SOS vesicle bilayer compared to the Palisades layer of SDS micelles. For a given phase ratio, CTAB/SOS vesicles are somewhat less retentive than SDS micelles, although retention factors comparable to those observed in 1.0–1.5% SDS can be obtained with 1.5–1.8% CTAB/SOS. A linear relationship was observed between phase ratio and retention factor, confirming the validity of the phase ratio model for these vesicles. Unique polar group selectivities and positional isomer shape selectivities were obtained with CTAB/SOS vesicles, with both types of selectivities being nearly independent of the phase ratio. For four sets of positional isomers, the elution order was always para < ortho < meta. Finally, the thermodynamics of solute retention was qualitatively similar to that reported for other surfactant aggregates (micelles and microemulsions); the enthalpic contribution to retention was consistently favorable for all compounds, whereas the entropic contribution was favorable only to hydrophobic solutes.
Development of Low‐Cost Advanced Composite Bipolar Plate for Proton Exchange Membrane Fuel Cell�
Authors: Kakati B. K. , Mohan V. 
Published: February 2008

AbstractThe bipolar plate is one of the most imperative components of proton exchange membrane fuel cells (PEMFC) which consumes up to 80% of weight and near about 50% of the total cost of the cell. Development of cost‐effective composite bipolar plate with high electrical conductivity and high mechanical strength is both technically and economically demanding. In this paper, a low‐cost advanced composite bipolar plate is developed by bulk moulding compression (BMC) technique. It is clear from the experiments that by increasing the matrix volume fraction, bulk density and electrical conductivity of a composite bipolar plate decrease but shore hardness increases. Test results clearly show that best overall properties are achieved when a constant volume fraction of polymer matrix and natural graphite is reinforced with synthetic graphite, carbon black and carbon fibre. This bipolar plate was found to have high conductivity, less porosity and high mechanical strength. The I–V characteristics in single cell test exhibited more uniform power density at both higher and lower current densities
Design of BaZr0.8Y0.2O3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)
Authors: D'Epifanio A. , Fabbri E. , Di Bartolomeo E. , Licoccia S. , Traversa E. 
Published: February 2008

AbstractBaZr0.8Y0.2O3–δ, (BZY), a protonic conductor candidate as an electrolyte for intermediate temperature (500–700 °C) solid oxide fuel cells (IT‐SOFCs), was prepared using a sol–gel technique to control stoichiometry and microstructural properties. Several synthetic parameters were investigated: the metal cation precursors were dissolved in two solvents (water and ethylene glycol), and different molar ratios of citric acid with respect to the total metal content were used. A single phase was obtained at a temperature as low as 1,100 °C. The powders were sintered between 1,450 and 1,600 °C. The phase composition of the resulting specimens was investigated using X‐ray diffraction (XRD) analysis. Microstructural characterisation was performed using field emission scanning electron microscopy (FE‐SEM). Chemical stability of the BZY oxide was evaluated upon exposure to CO2 for 3 h at 900 °C, and BZY showed no degradation in the testing conditions. Fuel cell polarisation curves on symmetric Pt/BZY/Pt cells of different thicknesses were measured at 500–700 °C. Improvements in the electrochemical performance were obtained using alternative materials for electrodes, such as NiO‐BZY cermet and LSCF (La0.8Sr0.2Co0.8Fe0.2O3), and reducing the thickness of the BZY electrolyte, reaching a maximum value of power density of 7.0 mW cm–2 at 700 °C.
Hard Rock TBM Cutterhead Modeling for Design and Performance Prediction
Authors: Rostami Jamal 
Published: February 2008

AbstractAs the use of hard rock TBMs constantly continues to grow, so are the experiences gained in these projects and the challenges that need new solutions. Cutterhead modeling has been a successful tool used by the industry at various levels of sophistications relative to the end use. These models are based on the estimation of the cutting forces and can be used for cutterhead design optimization as well as performance estimates. While these models have proven to be useful in these areas, there is still room for improving their accuracy to account for different rock features and rock mass properties. New and emerging technologies in cutter and machine manufacturing can be assisted by the use of these models in optimizing their use or assessing their potentials. This paper reviews the state of the art of modeling used for design and performance prediction of hard rock TBMs. A brief overview of the available models will be offered and their strength and shortcomings will be discussed.
An Integrated Approach to Penetration, Advance Rates and Disc Cutter Wear for Hard Rock TBM Drives
Authors: Alber Michael 
Published: February 2008

AbstractTunnel boring machines (TBM) are increasingly used for excavating subsurface infrastructure such as road and railway, water supply and sewer tunnels, to name a few applications. When designing a hard rock TBM drive it is necessary to appreciate all interactions of the rock mass to be tunnelled with the TBM. This paper deals specifically with these interactions and suggests an integrated approach in estimating hard rock TBM performance, such as the penetration rate, the advance rate and the disc cutter wear.
Abrasiveness Assessment for Hard Rock Drilling
Authors: Plinninger Ralf J. 
Published: February 2008

AbstractThe wear of drilling tools in mining and tunnelling has always been a predominant factor for the costs of hard rock excavation. This fact is not only related to material and personnel costs arising from drill bit maintenance and replacement but also because of the direct and negative impact of a worn drill bit on the drilling performance. This paper presents typical machinery, tools and basic findings on wear and performance interactions as well as drilling tool wear mechanisms. Based on this theoretical background, methods and classifications for on‐site investigation of encountered tool wear rate and wear types are presented. The paper then summarises laboratory approaches for assessing of rock abrasiveness in order to predict drilling tool wear from geotechnical investigations.