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The fatigue performance of dissimilar metal welded components has an important influence on the service reliability of spacecraft. The fatigue life and fatigue fracture mechanism of dissimilar metal welded joints of QCr0.8 copper alloy and 1Cr21Ni5Ti stainless steel were investigated. The copper-steel composite plate was properly prepared by electron beam welding. The microstructure and composition of welding seam were characterized and analyzed by metallographic microscope. Mechanical properties of welded joints were tested using electronic tensile testing machine and fatigue testing machines. Scanning electron microscopy was used to observe the fatigue fracture in different cycles. The results show that the overall metallurgical bonding of the two metals is good, however, the local fusion zone on the steel side has a large area and extends into the weld from the steel base. The tensile specimens of the copper-steel electron beam welding all fracture at the minimum section of the weld, and the average fatigue limit of the fatigue specimens is 48.04 MPa and they all fracture at the minimum section of the weld. In the high cycle fatigue sample, a single crack source is observed at the endpoint of the weld top surface, while in the low cycle fatigue sample, more crack sources are observed on the top and bottom surface and inside of the weld. The final fracture zone of both samples is located in the copper alloy matrix.It can be seen in the process of fatigue fracture, the number of crack sources is different between high and low cycle fracture, but in both cases, the cracks are easy to initiate at the minimum section of the weld and spread to the copper alloy matrix.

Understanding the melting behavior of metals at the microlevel and atomic level has been experimentally challenging due to the involvement of multiple phases at ultrafast time scale. By using the confocal scanning laser high-temperature microscope, differential scanning calorimetry, and environmental transmission electron microscope, we observed the transient process during melting of silver (Ag) nanoparticles below the equilibrium melting point. The melting point of Ag nanoparticles with the diameter of 60–120 nm is found to decrease by 100–400 °C, and the melting process is accompanied by a geometrical transformation at 840 °C, from an irregular polyhedron to a nearly spherical crystallinelike liquid with smooth facets. These results indicate that the melting of metal nanoparticles is not a direct sharp transformation from crystal to liquid but a gradual process via a certain intermediate state. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of Fe–0.35C–3.2Al–5Mn (in wt%, same later) hot‐rolled medium‐manganese steels are systematically investigated. The results show that ultrafine‐grained duplex phases with bimodal morphologies of lath and equiaxed are obtained with intercritical annealing at 750 °C for 1 h, along with ultimate tensile strength of 950 MPa and total elongation of 71.2%, attributed to the dislocation slip and deformation of ferrite matrix, accompanied by the synergetic twinning of retained austenite plus transformation of retained austenite to martensite. The newly developed medium‐manganese steels, which exhibit an excellent product of ultimate tensile strength and total elongation of 67.6 GPa·%, demonstrate great practical applications. [ABSTRACT FROM AUTHOR]

Two proteins, SghA and SghR, which were recently identified and characterized as novel bacterial virulence factors regulating the infection of plant hosts by Agrobacterium, were cloned, overexpressed and purified with high yield. Both SghA and SghR form dimers in solution. The purified SghA and SghR were crystallized and the crystals diffracted to 1.9 and 2.1 Å resolution, respectively. Data were collected and processed, and the crystallographic parameters were within acceptable ranges. These results will help in the determination of their structures in order to uncover the molecular mechanism of how these two proteins together control the release of plant defence signals against agrobacteria during pathogen-host interaction. [ABSTRACT FROM AUTHOR]

ABSTRACT Nifedipine is a dihydropyridine calcium channel blocker used widely in the management of hypertension and other cardiovascular disorders. In this work, a simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated to determine nifedipine in dog plasma using nimodipine as the internal standard. Chromatographic separation was carried out on a C8 column. The mobile phase consisted of a mixture of acetonitrile, water and formic acid (60:40:0.2, v/v/v) at a flow rate of 0.5 mL/min. Detection was performed on a triple quadrupole tandem mass spectrometer in selected reaction monitoring mode via an atmospheric pressure chemical ionization source. The method has a lower limit of quantification of 0.20 ng/mL with consumption of plasma as low as 0.05 mL. The linear calibration curves were obtained in the concentration range of 0.20-50.0 ng/mL ( r = 0.9948). The recoveries of the liquid extraction method were 74.5-84.1%. Intra-day and inter-day precisions were 4.1-8.8 and 6.7-7.4%, respectively. The quantification was not interfered with by other plasma components and the method was applied to determine nifedipine in plasma after a single oral administration of two controlled-release nifedipine tablets to beagle dogs. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the first paragraph, this sentence was cited incorrectly. The cited work was done by Nogita et al. Importantly, the density changes with the structural evolutions. It may be catastrophic to the intrinsically brittle IMC as reported by Nogita et al. that more cracks were observed at the interface of Sn-Cu/Cu if no Ni was added to inhibit the transformation.4 The correct citation is as follows: Importantly, the density changes with the structural evolutions. It may be catastrophic to the intrinsically brittle IMC as reported by Nogita et al. that more cracks were observed at the interface of Sn-Cu/Cu if no Ni was added to inhibit the transformation.8 The publisher regrets the error. [ABSTRACT FROM AUTHOR]