291   A model for the yield strength anomaly of Fe-Al A model for the yield strength anomaly of Fe-Al    1998 A phenomenological model is introduced for the temperature dependence of the yield strength of Fe-Al. The key feature of the model is that it incorporates hardening by thermal vacancies to account for the yield strength anomaly. Since the vacancy concentration CV varies as exp(-1/T) and the hardening due to vacancies varies as C1/2v, the model predicts at intermediate temperatures an exponential increase in strength with increasing temperature. This increasing strength is terminated by the onset... 查看全文

292   Adsorption and Diffusion of Li on Pristine and Defective Graphene Adsorption and Diffusion of Li on Pristine and Defective Graphene Xiaofeng Fan*†, W.T. Zheng*†, and Jer-Lai Kuo‡    2012 With first-principles DFT calculations, the interaction between Li and carbon in graphene-based nanostructures is investigated as Li is adsorbed on graphene. It is found that the Li/C ratio of less than 1/6 for the single-layer graphene is favorable energetically, which can explain what has been observed in Raman spectrum reported recently. In addition, it is also found that the pristine graphene cannot enhance the diffusion energetics of Li ion. However, the presence of vacancy defects can incr... 查看全文

293   Antifriction properties of new fluorine-containing derivatives of natural graphite Antifriction properties of new fluorine-containing derivatives of natural graphite T. I. Gorbunova, A. Ya. Zapevalov, D. N. Bazhin, L. G. Korshunov, V. S. Gaviko;V. I. Saloutin    2012 Interaction of natural graphite with potassium salts of perfl uoro(ω-chloroperfl uoro)carboxylic acids in the presence of potassium persulfate was studied. The derivatives obtained were used as independent lubricants for a chromium-containing-steel friction pair. 查看全文

294   Model for the yield strength anomaly in FeAl Model for the yield strength anomaly in FeAl    1997 A phenomenological model is used to explain the yield strength anomaly in FeAl. The model incorporates hardening by thermal vacancies at intermediate temperatures, and dislocation creep at elevated temperatures. Since the vacancy concentration increases exponentially with increasing temperature, the model predicts an exponential increase in strength with increasing temperature. This increasing strength is terminated by the onset of dislocation creep. The model captures the experimentally-observe... 查看全文

295   Numerical simulation of yield loci for PST crystals of TiAl Numerical simulation of yield loci for PST crystals of TiAl    1997 The yield strength of polysynthetically twinned (PST) crystals of TiAl depends on the orientation angle between the lamellar boundaries and the load axis. It is the aim of this work to model this anisotropic behaviour. A micromechanical model is employed which considers the lamellar microstructure and the deformation mechanisms such as ordinary slip and deformation twinning in γ-TiAl. Since the calculated and measured yield strength data show good agreement in the case of uniaxial loading,... 查看全文

296   Functionalization of Carbon Nanotubes with Vaska's Complex:  A Theoretical Approach Functionalization of Carbon Nanotubes with Vaska's Complex:  A Theoretical Approach Francesco Mercuri* and Antonio Sgamellotti    2006 The functionalization of single-walled carbon nanotubes (CNTs) with Vaska's complex trans-Ir(CO)Br(PPh3)2 has been investigated by means of hybrid quantum mechanics/molecular mechanics (QM/MM) calculations. The formation of a stable adduct has been experimentally evidenced by Wong et al. (Nano Lett. 2002, 2, 49), but microscopical details on the metal?nanotube interaction are still unclear. Our calculations show a low propensity to η2 coordination of Vaska's complex with the perfect hexagonal n... 查看全文

297   Prediction of the mechanical properties and fracture mechanical values of welded joints out of pipeline-steels (X70 and X80) Prediction of the mechanical properties and fracture mechanical values of welded joints out of pipeline-steels (X70 and X80)    2007 Nowadays the pipeline-steels X70 and X80 are mainly used for onshore-pipelines and a lot of money is spent world-wide in finding the right joining process for the circumferential welds of these pipes. A worldwide central collection of welding variables and efficient processing could result into a prediction of the mechanical properties and fracture mechanical values out of the data of the preceding joining process and would save a lot of trial and error and therefore costs. This paper deals with... 查看全文

298   1,3-Diphenylpropan-1-one 1,3-Diphenylpropan-1-one Bjouml;rn Gschwend, Benoicirc;t Pugin, Andreas Bertogg and Andreas Pfaltz    0 查看全文

299   Metallurgically based development of high strength (YS > 700 MPa) thin hot strips by Arvedi I.S.P. technology Metallurgically based development of high strength (YS > 700 MPa) thin hot strips by Arvedi I.S.P. technology    2008 A Nb-Ti-B microalloyed steel with a lean chemical composition was designed in order to achieve high strength thin hot rolled strips (Yield Strength > 700 MPa), exploiting the peculiar thermo-mechanical process by Arvedi In-line Strip Production (I.S.P.) technology. Results of metallurgical modelling, laboratory tests, pilot trials and industrial trials were used to identify the optimum conditions to obtain microstructures with the desired mechanical properties directly from the hot strip mill... 查看全文

300   Influence of the yield strength gradient on the fracture resistance in FGMs Influence of the yield strength gradient on the fracture resistance in FGMs    1999 In materials with local changes in yield strength, the near-tip crack driving force becomes different from the applied far-field value. This effect is termed here as the plasticity gradient effect. A model is developed that allows us to derive analytical expressions to quantify the plasticity gradient effect for smooth and abrupt variations in yield strength. The predictions of the model agree well with previous finite element computations and available experimental observations. The model can b... 查看全文

301   Enantioselective IrI-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy Enantioselective IrI-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy Riichir#x1d2; Chucirc;j#x1d2;, Mika Hrkouml;nen and Jukka V. Seppl    2011 Enantioenriched bicyclo[4.1.0]hept-2-enes were synthesized by IrI-catalyzed carbocyclization of 1,6-enynes. No chiral ligands were used, CO and PPh3 were the only ligands bound to iridium. Instead, the stereochemical information was localized on the counterion of the catalyst, generated in situ by reaction of Vaska’s complex (trans-[IrCl(CO)(PPh3)2]) with a chiral silver phosphate. Enantiomeric excesses up to 93 % were obtained when this catalytic mixture was used. 31P NMR an... 查看全文

302   The Significance of Fluorides in Fish Protein Concentrates The Significance of Fluorides in Fish Protein Concentrates    2009 The biological availability of the fluoride in fish protein concentrates appears to be one-fourth to one-half that of sodium fluoride added to casein diets fed rats. 查看全文

303   Theoretical strength and onset of yielding in nanoindentation Theoretical strength and onset of yielding in nanoindentation    2002 Quantum-mechanical (ab initio) approach for determining theoretical (ideal) tensile and shear strength in metals and intermetallics is briefly outlined and, as an example, tensile test for defect-free MoSi2 is simulated. Theoretical values of tensile and shear strength are compared with those obtained from loading of whiskers and from nanoindentation experiments. As nanoindentation tests can sample defect-free volumes, the onset of yielding should correspond to theoretical shear strength. Possib... 查看全文

304   Effect of interfacial bonding upon compressive strength and fracture energy of carbon fiber reinforced polymer (CFRP) composite: A theoretical investigation Effect of interfacial bonding upon compressive strength and fracture energy of carbon fiber reinforced polymer (CFRP) composite: A theoretical investigation    1993 Under compression, polyacrylonitrile (PAN) based carbon fiber reinforced polymer (CFRP) composites fail by fiber microbuckling. The compressive strength of CFRP is known to be dependent upon the properties of the matrix and the fiber/matrix interfacial bond. Two-dimensional analytical models can not properly model interfacial stress distributions to address this relationship. An approximate three-dimensional micromechanics model for compressive behavior. has therefore been developed and applied ... 查看全文

305   Asymmetric Markovian analysis of the polymerization mechanism of propene by ziegler-natta catalysis and external alkoxysilane donors Asymmetric Markovian analysis of the polymerization mechanism of propene by ziegler-natta catalysis and external alkoxysilane donors Riichir#x1d2; Chucirc;j#x1d2;, Mika Hrkouml;nen and Jukka V. Seppl    2011 The formulae for conditional probabilities are derived with the term of NMR triad tacticities for the polymers whose polymerization process is described by an asymmetric Markovian process. The formulae obtained are applied to the polypropylene polymerized by Ziegler-Natta catalysis with external alkoxysilane donors. For both, unfractionated samples and heptane-insoluble fractions, four evidences are clarified as follows: Don the transformation from symmetric to (fluctuating) asymmetric sites the... 查看全文

306   A field biopsy method for fluoride determinations in human surface enamel A field biopsy method for fluoride determinations in human surface enamel    2006 ABSTRACT An enamel biopsy method was developed that is especially intended for use under primitive clinical conditions in field studies. Three successive enamel layers, each of 1 μm or less, were etched off the same delimited area of 3 mm2 by means of perchloric acid, using a microsampler with disposable tips. The biopsy technique was applicable to the vestibular surface of almost all teeth, causing no perceptible damage to the enamel surface. Based on cumulated data from the successive ename... 查看全文

307   Predicting the shear strength of reinforced concrete beams using artificial neural networks Predicting the shear strength of reinforced concrete beams using artificial neural networks    2004 The application of artificial neural networks (ANNs) to predict the ultimate shear strengths of reinforced concrete (RC) beams with transverse reinforcements is investigated in this paper. An ANN model is built, trained and tested using the available test data of 176 RC beams collected from the technical literature. The data used in the ANN model are arranged in a format of nine input parameters that cover the cylinder concrete compressive strength, yield strength of the longitudinal and transve... 查看全文

308   Design of high strength steel columns at elevated temperatures Design of high strength steel columns at elevated temperatures    2008 The main objective of this paper is to study the behaviour and design of high strength steel columns at elevated temperatures using finite element analysis. In this study, equations predicting the yield strength and elastic modulus of high strength steel and mild steel at elevated temperatures are proposed. In addition, stress-strain curve model for high strength steel and mild steel materials at elevated temperatures is also proposed. The numerical analysis was performed on high strength steel ... 查看全文

309   Corrigendum: Direct Asymmetric -Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts Corrigendum: Direct Asymmetric -Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts Katalin Barta, Matthias Eggenstein, Markus Houml;lscher, Giancarlo Franciograve; and Walter Leitner    2012 查看全文

310   Multispectra method for error reduction of the quantized Fourier modulus in the iterative Fourier transform. algorithms used for phase retrieval Multispectra method for error reduction of the quantized Fourier modulus in the iterative Fourier transform. algorithms used for phase retrieval Shiyuan Yang;Hiroaki Takajo    0 A multispectra method is proposed for the error reduction of the quantized Fourier modulus in the iterative Fourier transform. algorithms used for phase retrieval. The Fourier modulus is usually obtained by measuring the Fourier intensity with a digital device, thus the quantization error caused in the measurements of Fourier intensity leads to the error of the reconstructed object when iterative Fourier transform. algorithms are used. The idea of the multispectra method uses several Fourier int... 查看全文

311   Effect of dislocation source length on yield strength of nanostructured metallic multilayer thin films Effect of dislocation source length on yield strength of nanostructured metallic multilayer thin films    2008 There is great interest in metallic multilayer thin films with the layer thickness on the order of nanometers due to their high hardness and strength. The yield strength deviates from Hall-Petch and Orowan predictions with layer thickness as the controlling factor, and other factors are in need to explain this phenomenon. In this work, the effect of dislocation source length on yield strength of multilayer system in the nanoscale regime is investigated using a three dimensional cellular automato... 查看全文

312   Direct Asymmetric -Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts† Direct Asymmetric -Allylation of Aldehydes with Simple Allylic Alcohols Enabled by the Concerted Action of Three Different Catalysts† Katalin Barta, Matthias Eggenstein, Markus Houml;lscher, Giancarlo Franciograve; and Walter Leitner    2011 查看全文

313   INFLUENCES OF INTERFACIAL BONDING STRENGTH AND SCATTER OF FIBRE STRENGTH ON TENSILE BEHAVIOUR OF UNIDIRECTIONAL METAL MATRIX COMPOSITES. INFLUENCES OF INTERFACIAL BONDING STRENGTH AND SCATTER OF FIBRE STRENGTH ON TENSILE BEHAVIOUR OF UNIDIRECTIONAL METAL MATRIX COMPOSITES.    1988 The influences of interfacial bonding strength and scatter of strength of fibres on tensile behaviour of unidirectional metal matrix composites, whose matrix has low yield stress in comparison to the strength of fibres, were studied using the Monte-Carlo simulation technique using two-dimensional model composites. The following results were obtained. The strength of composites increases with increasing bonding strength, especially when the bonding strength exceeds the shear yield stress of the m... 查看全文

314   Neutral Nazarov-Type Cyclization Catalyzed by Palladium(0)† Neutral Nazarov-Type Cyclization Catalyzed by Palladium(0)†    2012 查看全文

315   Prediction of mechanical properties of extra deep drawn steel in blue brittle region using Artificial Neural Network Prediction of mechanical properties of extra deep drawn steel in blue brittle region using Artificial Neural Network    2010 Blue brittle region also known as dynamic strain ageing (DSA) regime is very important in the materials because in this region material properties behave in very unpredictable ways. In this work, Artificial Neural Network (ANN) models are developed for the prediction of mechanical properties such as yield strength (YS), ultimate tensile strength (UTS), % elongation, strength coefficient (K) and strain hardening exponent (n) for the extra deep drawn (EDD) quality steel in blue brittle region. To ... 查看全文

316   In-plane anisotropy in tensile deformation and its influence on the drawability of Nimonic c-263 alloy sheets In-plane anisotropy in tensile deformation and its influence on the drawability of Nimonic c-263 alloy sheets    2011 An effort has been made to comprehensively evaluate and rationalize the in-plane anisotropy in tensile properties and the effect of aging on the nature of deformation (strain hardening behaviour) and formability characteristics, especially the limit drawing ratio and forming limit diagram. Despite weak crystallographic texture and excellent ductility and high work hardening exponents, the alloy sheets of C-263 exhibit significant extent of in-plane anisotropy in its tensile properties and yield ... 查看全文

317   Advanced high strength steel sheet forming and springback simulation Advanced high strength steel sheet forming and springback simulation    2010 With the increasing use of finite element analysis method in sheet forming simulations, springback predictions of advanced high strength steel (AHSS) sheet are still far from satisfactory precision. The main purpose of this paper was to provide a method for accurate springback prediction of AHSS sheet. Material model with Hill'48 anisotropic yield criterion and nonlinear isotropic/kinematic hardening rule were applied to take account the anisotropic yield behavior. and the Bauschinger effect dur... 查看全文

318   Piston-on-three-ball versus piston-on-ring in evaluating the biaxial strength of dental ceramics Piston-on-three-ball versus piston-on-ring in evaluating the biaxial strength of dental ceramics    2011 Objectives: Piston-on-three-ball tests have been selected by the International Organization for Standardization to establish ISO 6872 for the evaluation of the biaxial strength of dentistry-ceramic materials. However, the formula adopted in ISO 6872 for the fracture load-biaxial strength relationship was an approximate equation originally derived for piston-on-ring tests of monolayered discs. This formula was modified and extended to the case of multilayered discs subjected to piston-on-ring loa... 查看全文

319   Plaque surface area after rinsing with a low-level fluoride-containing Darjeeling tea Plaque surface area after rinsing with a low-level fluoride-containing Darjeeling tea Alice M. Horowitz RDM and P. Jean Frazier MPH    2007 Plaque surface area after rinsing with a tea, containing low levels of fluoride, was evaluated in 30 human volunteers with a single-blind, one-operator, three-period, three-treatment cross-over study. The mouthwashes employed were: (1) tea (Darjeeling first flush:< 0.2 ppm F), (2) Meridol®, (3) control (tap water:< 0.2 pprn F). During the experiment the participants refrained from oral hygiene procedures and rinsed their mouth three tiroes a day after each meal with 20 ml of the respec... 查看全文

320   Flake-Shell Capsules: Adjustable Inorganic Structures Flake-Shell Capsules: Adjustable Inorganic Structures Bo Zhang, Hui Wang, Guo-Qiang Lin and Ming-Hua Xu    2012 查看全文

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