bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minicrystallization in directionally solidified multicrystalline silicon and its effect on the photovoltaic properties of solar cells
Authors: Liu Bingfa , Chen Nan , Du Guoping , Liu Guihua , Li Yangsheng , Sun Wei , Rossetto Pietro 
Published: June 2011

AbstractIn this paper, we report the occurrence of minicrystallization in multicrystalline silicon ingots grown by the directional solidification method and its effect on the photovoltaic (PV) properties of multicrystalline silicon solar cells. Minicrystallization in multicrystalline silicon ingots sometimes occurs when the directional solidification process is not properly optimized, and it causes much smaller grain sizes in the minicrystallized regions. Serious shunting behaviour has been observed in multicrystalline silicon solar cells containing minicrystallized regions, and it is highly localized to these minicrystallized regions. Minicrystallization in multicrystalline silicon considerably deteriorates the overall PV properties of solar cells.
Formation of CuInSe2 from Cu2Se and In2Se3 compounds
Authors: Chen Daigao , Wang Deliang 
Published: June 2011

AbstractChalcopyrite α‐CuInSe2 (α‐CIS) was prepared from mixed powders of Cu2Se and In2Se3 by annealing in the Se‐ and the non‐Se environments. The mechanically ground powders were in an overall amorphous state. The mechanical alloying produced Cu3Se2 and CuSe compounds. At relatively low temperature, Cu3Se2 decomposed, Cu2−xSe and CuSe formed. The reaction for the formation of α‐CuInSe2 occurred essentially at a temperature at ∼350 °C in both the Se‐ and the non‐Se environments. In the non‐Se environment, reactions occurred by a solid–solid reaction and a certain amount of Se were released from the mixed powder, resulting in poor crystalline α‐CuInSe2 powders. When annealed in the Se environment, low‐melting Se‐rich Cu‐Se compounds were produced during reaction. The reactions occurred by a liquid–solid reaction above 450 °C. Large‐grained and good crystalline quality of chalcopyrite CIS with near stoichiometric atomic ratio was obtained above 450 °C.
The origin for increase of magnetic moment of Co in Co‐doped SnO2 with oxygen vacancies
Authors: Wang Hongxia , Zong Zhaocun , Li Peng , Yan Yu 
Published: June 2011

AbstractIn Co‐doped SnO2 fivefold degenerate Co‐3d states split into five singlet states. The magnetic moment of Co is mainly contributed by the spin polarization of Co‐dxy states. The introduction of oxygen vacancies largely increases the magnetic moment of Co. The increase of Co magnetic moment is caused by the conversion of spin–spin coupling between Co and its neighboring O atoms from antiparallel to parallel, which attributes to the hybridization and electrons transfer between oxygen vacancy impurity states and Co‐3d states.
Revisiting magnetism of capped Au and ZnO nanoparticles: Surface band structure and atomic orbital with giant magnetic moment
Authors: Hernando Antonio , Crespo Patricia , García Miguel Angel , Coey Michael , Ayuela Andrés , Echenique Pedro Miguel 
Published: June 2011

AbstractIn this article we review the exotic magnetism of nanoparticles (NPs) formed by substances that are not magnetic in bulk as described with generality in Section 1. In particular, the intrinsic character of the magnetism observed on capped Au and ZnO NPs is analysed. X‐ray magnetic circular dichroism (XMCD) analysis has shown that the magnetic moments are intrinsic and lie in the Au and Zn atoms, respectively, as analysed in Section 2, where the general theoretical ideas are also revisited. Since impurity atoms bonded to the surface act as donor or acceptor of electrons that occupy the surface states, the anomalous magnetic response is analysed in terms of the surface band in Section 3. Finally, Section 4 summarizes our last theoretical proposal.
Theoretical study of the polymerization of p‐tert‐butyl‐anisol
Authors: Ayadi Sameh , Mignon Pierre , Abderrabba Manef , Chermette Henry 
Published: June 2011

AbstractThe stereoselective formation of dimers and trimers of p‐tert‐butyl‐anisol by electrochemical oxidation has been theoretically studied. For the purpose, density functional theory calculations with the PBE exchange‐correlation functional have been performed with a triple zeta plus polarization basis set. A mechanism has been proposed by validating one suggestion of the experimentalists, whereas other reaction pathways suggested by experimentalists have been ruled out. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
The classical‐map hyper‐netted‐chain (CHNC) method and associated novel density‐functional techniques for warm dense matter
Authors: Dharma‐Wardana M. W. C. 
Published: June 2011

AbstractThe advent of short‐pulse lasers, nanotechnology, as well as shock‐wave techniques have created new states of matter (e.g., warm dense matter) that call for new theoretical tools. Ion correlations, electron correlations, as well as bound states, continuum states, partial degeneracies and quasi‐equilibrium systems need to be addressed. Bogoliubov's ideas of timescales can be used to discuss the quasi‐thermodynamics of nonequilibrium systems. A rigorous approach to the associated many‐body problem turns out to be the computation of the underlying pair‐distribution functions gee, gei, and gii, that directly yield nonlocal exchange‐correlation potentials, free energies etc., valid within the timescales of each evolving system. An accurate classical map of the strongly‐quantum uniform electron‐gas problem given by Dharma‐wardana and Perrot is reviewed. This replaces the quantum electrons at T = 0 by an equivalent classical fluid at a finite temperature Tq, and having the same correlation energy. The classical map is used with classical molecular dynamics (CMMD) or hyper‐netted‐chain integral equations (CHNC) to determine the pair‐distribution functions (PDFs), and hence their thermodynamic and linear transport properties. The CHNC is very efficient for calculating the PDFs of uniform systems, while CMMD is more adapted to nonuniform systems. Applications to 2D and 3D quantum fluids, Si metal‐oxide‐field‐effect transistors, Al plasmas, shock‐compressed deuterium, two‐temperature plasmas, pseudopotentials, as well as calculations for parabolic quantum dots are reviewed. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
On series of signed vectors and their rearrangements
Authors: Banaszczyk Wojciech 
Published: June 2011

AbstractLet x1,…,xm∈
\input amssym $ \Bbb R$n be a sequence of vectors with ∥xi∥2 ≤ 1 for all i. It is proved that there are signs ε1,…,εm = ±1 such that

where C1, C2 are some numerical constants. It is also proved that there are signs ε,…,ε = ±1 and a permutation π of {1,…,m} such that

where C′ is some other numerical constant. © 2011 Wiley Periodicals, Inc. Random Struct. Alg., 2011
ATR‐FTIR Kretschmann spectroscopy for interfacial studies of a hidden aluminum surface coated with a silane film and epoxy I. Characterization by IRRAS and ATR‐FTIR
Authors: Öhman Maria , Persson Dan 
Published: June 2011

AbstractInterfacial analysis is essential in many areas of interest, for instance within the ongoing research on environmentally friendly pretreatments of metal surfaces. While studies of the hidden interface between a metal and polymer top‐coat are of great importance, properties of a surface confined between two media are difficult to analyze in detail. Within the two parts of this study, ATR‐FTIR spectroscopy in the Kretschmann geometry is employed as the main analytical tool to study the interface between a thermo‐cured epoxy and aluminum pretreated with a silane film. The technique requires model systems based on thin metal films, but in contrast to most analytical techniques it permits the analysis of a hidden interface. Initial characterization of the silane film formed from a pH‐regulated γ‐APS and BTSE solution was conducted by both ATR‐FTIR Kretschmann and IRRAS spectroscopy. Absorption bands were obtained at 1250–900 cm−1, assigned to SiO functionalities, and at ∼1570 and ∼1410 cm−1 assigned to acetate existing as a counter‐ion to γ‐APS. After application of the epoxy film, interfacial alterations were detected upon thermal curing including the densification of the epoxy film, the dehydration of aluminum and the formation of molecular epoxy reaction products. Few alterations could be assigned to the silane film. Calculated spectra derived from optical data can verify experimental results and aid data interpretation, and effects of metal oxidation of aluminum were confirmed by introducing gold as an additional substrate. The results showed that ATR‐FTIR Kretschmann spectroscopy is clearly a valuable tool for the study of hidden interfaces of stratified media. Copyright © 2011 John Wiley & Sons, Ltd.
Stress‐Temperature‐Transformation and Deformation‐Temperature‐Transformation Diagrams for an Austenitic CrMnNi as‐cast Steel
Authors: Kovalev A. , Jahn A. , Weiß A. , Wolf S. , Scheller P. R. 
Published: June 2011

AbstractStress‐Temperature‐Transformation (STT) and Deformation‐Temperature‐Transformation (DTT) diagrams are well‐suited to characterize the TRIP (transformation‐induced plasticity) and TWIP (twinning‐induced plasticity) effect in steels. The triggering stresses for the deformation‐induced microstructure transformation processes, the characteristic temperatures, the yield stress and the strength of the steel are plotted in the STT diagram as functions of temperature. The elongation values of the austenite, the strain‐induced twins and martensite formations are shown in the DTT diagram.The microstructure evolution of a novel austenitic Cr‐Mn‐Ni (16%Cr, 6% Mn, 6% Ni) as‐cast steel during deformation was investigated at various temperatures using static tensile tests, optical microscopy and the magnetic scale for the detection of ferromagnetic phase fraction. At the temperatures above 250 °C the steel only deforms by glide deformation of the austenite. Strain‐induced twinning replaces the glide deformation at temperatures below 250 °C with increasing strain. Below 100 °C, the strain‐induced martensite formation becomes more pronounced. The kinetics of the α'‐martensite formation is described according to stress and deformation temperatures. The STT and DTT diagrams, enhanced with the kinetics of the martensite formation, are presented in this paper.
First Principles Calculation of the Thermal Volume Expansion Coefficient of Tetragonal Zircon Dioxide
Authors: Lamowski Simon , Schmerler Steve , Kutzner Jürgen , Kortus Jens 
Published: June 2011

AbstractWe present a general method to calculate thermodynamical properties of crystalline materials from first principles based on density functional theory (DFT). In order to introduce temperature effects we calculate the phonon dispersion for different volumes which allows to include their entropic effects in the Helmholtz free energy. As an example we focus on the calculation of the thermal volume expansion coefficient of tetragonal ZrO2.
Einsatz von warmgefertigten Hohlprofilen mit Wanddicken bis 20 mm bei tiefen Temperaturen
Authors: Stranghöner Natalie , Lorenz Christoph , Krampen Jürgen 
Published: July 2011

AbstractWarmgefertigte Hohlprofile nach DIN EN 10210 werden derzeit in Europa hauptsächlich in Wanddicken bis 20 mm in der bei den Stahlhändlern in der Regel vorrätigen Güte S355J2H eingesetzt. Eine immer wieder kehrende Frage betrifft die Einsatzfähigkeit dieser Hohlprofile bei tiefen Temperaturen bedingt durch die in der Produktnorm festgelegte Prüftemperatur der Kerbschlagzähigkeit bei —20 °C: Ist ein Stahl der Güte S355J2H auch unterhalb von —20 °C Außentemperatur einsetzbar oder sollte aus Sicherheitsüberlegungen heraus lieber eine höherwertige Stahlgüte eingesetzt werden? Der vorliegende Beitrag beschreibt das Zähigkeitsverhalten von warmgefertigten Hohlprofilen auf der Basis experimenteller Untersuchungen und erläutert den Zusammenhang zwischen der in den Produktnormen geforderten Mindestzähigkeit bei definierter Prüftemperatur und dem bruchmechanisch basierten Sprödbruchkonzept der DIN EN 1993‐1‐10 zur Stahlgütewahl.The use of hot‐finished hollow sections with wall thicknesses up to 20 mm at low temperatures. In Europe, hot‐finished hollow sections according to DIN EN 10210 are mainly used with wall thicknesses up to 20 mm and steel grade S355J2H which is normally in stock at the steel suppliers. A recurring question concerns the usability of those hollow sections at low temperatures due to the test temperature of impact toughness at —20 °C set in the product standard: Is a steel grade S355J2H applicable below —20 °C service temperature, or should, by security considerations, rather a higher‐quality steel be used? This paper describes the toughness behaviour of hot‐finished hollow sections based on experimental studies and explains the relationship between the required impact toughness in the product standards at a defined test temperature and the fracture mechanics based concept for the choice of steel material of DIN EN 1993‐1‐10.
Korrekturvorschläge für die DIN EN 1993‐1‐8 zum Thema Hohlprofilanschlüsse
Authors: Wardenier Jaap , Puthli Ram 
Published: July 2011

AbstractDie aktuelle Fassung der DIN EN 1993‐1‐8 enthält ein umfangreiches Kapitel zum Thema Anschlüsse mit Hohlprofilen. Im vorliegenden Beitrag werden hierzu Korrekturvorschläge vorgestellt und sofern erforderlich ihr wissenschaftlicher Hintergrund erläutert. Die Korrekturvorschläge betreffen Fehler und Unklarheiten im Text, sinnentstellende Fehler bei Gleichungen und Anwendungsgrenzen, weiterhin Korrekturen, die wegen der Ausdehnung des Anwendungsbereichs auf Stähle S 460 erforderlich sind und solche, die auf Forschungsergebnissen der letzten 20 Jahre basieren, die Sicherheitslücken aufgezeigt haben. Insbesondere wird der lastmindernde Einfluss großer Zugnormalspannungen im Gurt auf die Knotentragfähigkeit diskutiert.Proposed corrections to EN 1993‐1‐8, dealing with hollow section joints. The latest version of Eurocode EN 1993‐1‐8 has an exclusive chapter dealing with hollow section joints. This article proposes corrections relating to hollow section joints and explains the relevant research background where necessary. The proposed corrections concern errors in the text, the formulation and the validity range, confusing statements and corrections necessary for the extension of steel grades up to S 460. Also, corrections based upon research results in the last 20 years are given, which have shown that the safety level is lower than expected, such as the influence of chord tensile stress on the joint capacity.
Evaluation of residual welding stresses and fatigue crack behavior in tubular K‐joints in compression
Authors: Acevedo Claire , Nussbaumer Alain , Drezet Jean‐Marie 
Published: July 2011

AbstractTubular bridge design has to deal with fatigue issues. The fatigue susceptibility of these bridges, composed of circular hollow section profiles welded together in K‐joints, is mainly due to stress concentrations, to welding imperfections and to tensile residual stresses induced by the welding process.Since these residual stresses are unknown for K‐joints, measurements were carried out in vicinity of weld toes using the incremental hole‐drilling method, X‐ray diffraction and in particular neutron diffraction. Results from these techniques show that on the first millimeters from the surface, the most important tensile residual stresses are oriented perpendicular to the weld direction and reach the yield strength. Fatigue tests on two large‐scale truss specimens were carried out. They show that tensile residual stresses have a strong influence on crack propagation in K‐joints under applied compressive stresses down to a crack depth of 2 to 3 mm from the surface. Thermo‐mechanical analyses are performed in 3D using two finite element codes: ABAQUS and MORFEO. Computed residual stresses in the region surrounding the weld are compared with measured residual stresses in order to discuss the ability of the simulations to reproduce the residual stress field pattern and estimate the stress values.Ermittlung von Eigenspannungen und Verhalten von Ermüdungsrissen in geschweißten K‐Hohlprofilverbindungen unter Druck. Bei der Konstruktion von Brücken aus Rundhohlprofilen sind Materialermüdungsprobleme zu beachten. Derartige Brücken sind durch K‐förmige Strebenverbindungen (im Folgenden K‐Verbindungen genannt) verschweißt. Ihre Anfälligkeit für Materialermüdung entsteht vor allem durch Spannungskonzentrationen sowie durch Unregelmäßigkeiten und Eigenspannungen, die beim Schweißen erzeugt werden.Da die Höhe dieser Eigenspannungen für K‐Verbindungen unbekannt ist, wurden Messungen in der Nähe der Schweißnahtübergänge durchgeführt. Messmethoden waren die inkrementelle Bohrlochmethode, die Röntgendiffraktometrie und insbesondere die Neutronendiffraktometrie. Die Messergebnisse zeigen, dass die wichtigsten Zug‐Eigenspannungen auf den ersten Millimetern unterhalb der Oberfläche rechtwinklig zur Schweißnaht verlaufen und die Streckgrenze erreichen. Ermüdungstests wurden an zwei großen Trägern durchgeführt. Sie zeigen, dass Zug‐Eigenspannungen bei gleichzeitig bestehenden Druckspannungen einen starken Einfluss auf Rissausbreitung in K‐Verbindungen haben; bis zu einer Tiefe von 2 bis 3 mm unterhalb der Oberfläche. Thermomechanische Analysen werden in 3D‐Modellen unter Verwendung zweier Finite‐Elemente‐Programme durchgeführt: ABAQUS und MORFEO. Hierdurch berechnete Eigenspannungen in der Umgebung der Schweißnaht werden mit den gemessenen Werten verglichen, um die Eignung der Simulationen zu prüfen, die Eigenspannungsfelder darzustellen und die Spannungswerte überschlägig zu ermitteln.
Production of L(+) lactic acid from sweet sorghum, date palm, and golden syrup as alternative carbon sources
Authors: Yadav Anil K. , Bipinraj Nirichan K. , Chaudhari Ambalal B. , Kothari Ramanlal M. 
Published: June 2011

AbstractLactic acid production has been carried out using (a) Lactobacillus delbruckii, (b) optimal production medium comprised of 10% carbon source derived from sweet sorghum (SS) (Sorghum bicolor)/golden syrup (GS; molasses after glucose crystallization)/date palm (DP) juice (Phoenix dactylifera L.), 1% yeast extract, 0.6% sodium acetate, 0.5% KH2PO4, and 0.5% MgSO4 · 7H2O, (c) in batch mode, (d) at 45 ± 1°C, 150 rpm, anaerobic condition, and pH 5.5 ± 0.1, and (e) sterilized CaCO3 powder at regular intervals for neutralization to promote optimal utilization of sugar. The lactic acid (LA) productivity was higher from the use of GS and less from SS as well as DP juice. Decolorization of carbon sources prior to use in fermentation gave LA, meeting food grade specifications.
Globalization of science education: Comment and a commentary
Authors: Fensham Peter J. 
Published: June 2011

AbstractThe globalized nature of modern society has generated a number of pressures that impact internationally on countries' policies and practices of science education. Among these pressures are key issues of health and environment confronting global science, global economic control through multi‐national capitalism, comparative and competitive international testing of student science achievement, and the desire for more humane and secure international society. These are not all one‐way pressures and there is evidence of both more conformity in the intentions and practices of science education and of a greater appreciation of how cultural differences, and the needs of students as future citizens can be met. Hence while a case for economic and competitive subservience of science education can be made, the evidence for such narrowing is countered by new initiatives that seek to broaden its vision and practices. The research community of science education has certainly widened internationally and this generates many healthy exchanges, although cultural styles of education other than Western ones are still insufficiently recognized. The dominance of English language within these research exchanges is, however, causing as many problems as it solves. Science education, like education as a whole, is a strongly cultural phenomenon, and this provides a healthy and robust buffer to the more negative effects of globalization. © 2011 Wiley Periodicals, Inc., Inc. J Res Sci Teach 48: 698–709, 2011
A novel way of visualizing the ductal and aortic arches by real‐time three‐dimensional ultrasound with live xPlane imaging
Authors: Xiong Y. , Chen M. , Chan L. W. , Ting Y. H. , Fung T. Y. , Leung T. Y. , Lau T. K. 
Published: June 2011

AbstractObjectiveTo describe a novel method of visualizing the ductal and aortic arches by real‐time three‐dimensional echocardiography with live xPlane imaging.MethodsLive xPlane imaging was used to display the ductal‐ and aortic‐arch views in 107 women with singleton pregnancies, including seven cases with suspected congenital heart defects (CHDs). The three vessels and trachea (3VT) view was obtained in such an orientation that either the pulmonary artery or the aorta was parallel to the direction of the ultrasound beam. The xPlane reference line was then placed across the targeted vessel, which in a normal case would provide an image of the corresponding arch view as a dual‐image display.ResultsOnce the 3VT view had been obtained, live xPlane imaging showed the aortic and ductal arches in all 100 normal cases. In seven cases with suspected CHD, the 3VT view was abnormal in five cases and normal in the other two. However, the ductal‐arch view demonstrated by live xPlane imaging was abnormal in five cases of conotruncal anomalies and normal in two cases in which conotruncal anomalies were excluded. CHDs were confirmed at autopsy following termination of pregnancy in five cases and on postnatal echocardiography in one case. The heart was found postnatally to be normal in one case of suspected CHD; in this case live xPlane imaging showed that the observed abnormal 3VT view was caused by a tortuous course of the thoracic aorta associated with an abnormal diaphragm.ConclusionLive xPlane imaging is a novel and relatively simple method of visualizing the ductal‐ and aortic‐arch views, and may potentially be a useful tool in the screening of fetal conotruncal and aortic‐arch anomalies. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
A request control scheme for data recovery in DVB‐IPDC systems with spatial and temporal packet loss
Authors: Yang Wen‐Hsin , Wang You‐Chiun , Tseng Yu‐Chee , Lin Bao‐Shuh Paul 
Published: June 2011

ABSTRACTRecently, digital video broadcasting‐handheld (DVB‐H) and IP datacast over DVB‐H (DVB‐IPDC) have been developed to support broadcasting services. DVB‐H is designed to support digital video broadcast for handheld devices, whereas DVB‐IPDC can integrate with an IP‐relay network to complement the data loss problem in DVB‐H. Assuming that WiMAX networks are adopted to support DVB‐IPDC, this paper points out two critical problems: group packet loss (GPL) and broadcast data handover (BDH). GPL occurs when there is a burst of retransmission requests for the same pieces of data with high spatial or temporal correlation. BDH happens when some devices that made the above requests handover to new serving cells. To solve these problems, we propose lazy wait and group acknowledgement schemes to alleviate duplicate requests by exploiting their spatial and temporal correlations. This not only reduces the requests submitted by neighboring devices in both space and time domains but also avoids handovering devices from sending duplicate requests in new cells. Through mathematical analysis, we show how to adaptively adjust the timers of lazy wait and group acknowledgement based on channel quality. Simulation results prove that our schemes can efficiently reduce retransmission requests and retransmission packets, thus alleviating congestion in the IP‐relay network. Copyright © 2011 John Wiley & Sons, Ltd.