Effect of Cyclic Stresses below the Endurance Limit on the Fatigue Life of 40Cr Steel

The effect of cyclic stresses below the endurance limit on the fatigue life of 40Cr medium-strength carbon steel is studied. Conventional constant-amplitude cyclic tests and specially designed variableamplitude ones are conducted under torsional loading at the stress ratio R = 0.1. The results show that the strengthening effect of cyclic stresses below the endurance limit can be reached if they are applied prior to the exceeding ones. Moreover, the stress amplitude, number of cycles and load sequence are found to be the three major strengthening effect-controlling factors.Изучено влияние циклических напряжений ниже предела выносливости на усталостную долговечность углеродистой стали средней прочности 40Cr. Выполнены стандартные циклические испытания с постоянной амплитудой и специально разработанное испытание с переменной амплитудой при крутящем усилии и коэффициенте асимметрии R = 0,1. Показано, что эффект упрочнения от циклических напряжений ниже предела выносливости достигается при их приложении до напряжений, превышающих этот предел. Установлено, что амплитуда напряжений, число циклов и схема нагружения являются тремя основными факторами, контролирующими эффект упрочнения

Bulk experimental evidence of half-metallic ferromagnetism in doped manganites

We report precise measurements and quantitative data analysis on the low-temperature resistivity of several ferromagnetic manganite films. We clearly show that there exists a T^{4.5} term in low-temperature resistivity, and that this term is in quantitative agreement with the quantum theory of two-magnon scattering for half metallic ferromagnets. Our present results provide the first bulk experimental evidence of half-metallic ferromagnetism in doped manganites.Comment: 4 pages, 4 figure

Validating process refinement with ontologies

Peer reviewedPublisher PD

Time-reversal symmetry breaking in the noncentrosymmetric Zr3Ir superconductor

We report the discovery of Zr3Ir as a structurally different type of unconventional noncentrosymmetric superconductor (with Tc=2.3 K), here investigated mostly via muon-spin rotation/relaxation (μSR) techniques. Its superconductivity was characterized using magnetic susceptibility, electrical resistivity, and heat capacity measurements. The low-temperature superfluid density, determined via transverse-field μSR and electronic specific heat, suggests a fully gapped superconducting state. The spontaneous magnetic fields, revealed by zero-field μSR below Tc, indicate the breaking of time-reversal symmetry in Zr3Ir and hence the unconventional nature of its superconductivity. By using symmetry arguments and electronic-structure calculations we obtain a superconducting order parameter that is fully compatible with the experimental observations. Hence, our results clearly suggest that Zr3Ir represents a structurally different member of noncentrosymmetric superconductors with broken time-reversal symmetry

Solidification of Al-Sn-Cu based immiscible alloys under intense shearing

The official published version of the Article can be accessed from the link below - Copyright @ 2009 The Minerals, Metals & Materials Society and ASM InternationalThe growing importance of Al-Sn based alloys as materials for engineering applications necessitates the development of uniform microstructures with improved performance. Guided by the recently thermodynamically assessed Al-Sn-Cu system, two model immiscible alloys, Al-45Sn-10Cu and Al-20Sn-10Cu, were selected to investigate the effects of intensive melt shearing provided by the novel melt conditioning by advanced shear technology (MCAST) unit on the uniform dispersion of the soft Sn phase in a hard Al matrix. Our experimental results have confirmed that intensive melt shearing is an effective way to achieve fine and uniform dispersion of the soft phase without macro-demixing, and that such dispersed microstructure can be further refined in alloys with precipitation of the primary Al phase prior to the demixing reaction. In addition, it was found that melt shearing at 200 rpm and 60 seconds will be adequate to produce fine and uniform dispersion of the Sn phase, and that higher shearing speed and prolonged shearing time can only achieve minor further refinement.This work is funded by the EPSRC and DT

Ab initio study of the beta$-tin->Imma->sh phase transitions in silicon and germanium

We have investigated the structural sequence of the high-pressure phases of silicon and germanium. We have focussed on the cd->beta-tin->Imma->sh phase transitions. We have used the plane-wave pseudopotential approach to the density-functional theory implemented within the Vienna ab-initio simulation package (VASP). We have determined the equilibrium properties of each structure and the values of the critical parameters including a hysteresis effect at the phase transitions. The order of the phase transitions has been obtained alternatively from the pressure dependence of the enthalpy and of the internal structure parameters. The commonly used tangent construction is shown to be very unreliable. Our calculations identify a first-order phase transition from the cd to the beta-tin and from the Imma to the sh phase, and they indicate the possibility of a second-order phase-transition from the beta-tin to the Imma phase. Finally, we have derived the enthalpy barriers between the phases.Comment: 12 pages, 16 figure

The development of pharyngeal taste buds in Hucho taimen (Pallas, 1773) larvae

This study aims to investigate the relationship between the development of pharyngeal taste buds (TBs) and first feeding of Hucho taimen. Larvae were fed with live food (water flea and tubifex) for 8 weeks. TBs of larval pharynx were histologically examined using light microscopy during the rearing experiment. The results showed that the first few TBs primordia were visible within the pharynx 27 days after hatch (DAH), which coincides with the onset of feeding, and the first few TBs with open receptor areas appear 45 DAH. TBs of pharynx were well developed 76 DAH. The number and size of TBs were quantified during larval development. The average number of pharynx was 8.63±1.15, 11.29±0.50, 14.50±1.06, and 17.78±0.47 TBs at 27, 36, 45, and 76 DAH, respectively. The number of TBs increased in both the upper and lower pharynx. The ratio of height to width of TBs showed an increase tendency, ranging from 0.81 to 1.11. The height of TBs showed an increase tendency after 29 DAH during the development. However, the width of TBs exhibited a low at 35 DAH. In conclusion, the development of pharyngeal TBs coincides with the first feeding, and this should lead to a better understanding of improvement of larval rearing in H. taimen hatcheries

Cosmic Evolution in Brans-Dicke Chameleon Cosmology

We have investigated the Brans-Dicke Chameleon theory of gravity and obtained exact solutions of the scale factor $a(t)$, scalar field $\phi(t)$, an arbitrary function $f(\phi)$ which interact with the matter Lagrangian in the action of the Brans-Dicke Chameleon theory and potential $V(\phi)$ for different epochs of the cosmic evolution. We plot the functions $a(t)$, $\phi(t)$, $f(t)$ and $V(\phi)$ for different values of the Brans-Dicke parameter. In our models, there is no accelerating solution, only decelerating one with $q>0$. The physical cosmological distances have been investigated carefully. Further the statefinder parameters pair and deceleration parameter are discussed.Comment: To be appear in "The European Physical Journal - Plus (EPJ Plus)",Extended version,15 pages, 17eps figure

High-field magnetization study of the S = 1/2 antiferromagnetic Heisenberg chain [PM Cu(NO3_3)2_2(H2_2O)2_2]n_n with a field-induced gap

We present a high-field magnetization study of the $S$ = 1/2 antiferromagnetic Heisenberg chain [PM Cu(NO$_3$)$_2$(H$_2$O)$_2$]$_n$. For this material, as result of the Dzyaloshinskii-Moriya interaction and a staggered $g$ tensor, the ground state is characterized by an anisotropic field-induced spin excitation gap and a staggered magnetization. Our data reveal the qualitatively different behavior in the directions of maximum and zero spin excitation gap. The data are analyzed via exact diagonalization of a linear spin chain with up to 20 sites and on basis of the Bethe ansatz equations, respectively. For both directions we find very good agreement between experimental data and theoretical calculations. We extract the magnetic coupling strength $J/k_B$ along the chain direction to 36.3(5) K and determine the field dependence of the staggered magnetization component $m_s$.Comment: 5 pages, 2 figures (minor changes to manuscript and figures

\psi(2S) Decays into \J plus Two Photons

Using \gamma \gamma J/\psi, J/\psi \ra e^+ e^- and $\mu^+ \mu^-$ events from a sample of $14.0\times 10^6$ \psip decays collected with the BESII detector, the branching fractions for \psip\ra \pi^0\J, \eta\J, and \psi(2S)\ar\gamma\chi_{c1},\gamma\chi_{c2}\ar\gamma\gamma\jpsi are measured to be B(\psip\ra \pi^0\J) = (1.43\pm0.14\pm0.13)\times 10^{-3}, B(\psip\ra \eta\J) = (2.98\pm0.09\pm0.23)%, B(\psi(2S)\ar\gamma\chi_{c1}\ar\gamma\gamma\jpsi) = (2.81\pm0.05\pm 0.23)%, and B(\psi(2S)\ar\gamma\chi_{c2}\ar\gamma\gamma\jpsi) = (1.62\pm0.04\pm 0.12)%.Comment: 7 pages, 6 figures. submitted to Phys. Rev.