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Spin relaxation induced by the interfacial effects in GaN/Al0.25Ga0.75N heterostructures was carefully investigated using a photon-energy-dependent time-resolved Kerr rotation spectrum. The existence of the interfacial localized states with potential fluctuations at the GaN/AlGaN heterointerface leads to photoluminescence peaks showing blue and S-shaped shifts owing to the excitation power and temperature, respectively. Photoexcited electrons in the localized states show a spin relaxation time longer than 1 ns because of the suppression of the D'yakonov–Perel’ (DP) scattering, while the spin relaxation time of free electrons was approximately only 10 ps because of the giant Rashba spin-orbit coupling induced by the interfacial polarization field under the framework of the DP scattering mechanism. Furthermore, it is found that the high electron mobility at the heterointerface results in a long spin diffusion length of 300 nm at high temperatures, which is promising for the development of GaN-based spintronic devices.

A serial of Ti-25 wt% Nb-(1, 3, 5) wt% Sn-(2, 4) wt% Cr alloys were designed with aim to obtain a single β phase matrix in the microstructure for high performance. The newly designed alloys were produced through cold crucible levitation melting to characterize the effect of Cr and Sn on the microstructure, phase constitution and mechanical properties of the titanium alloys. All the investigated alloys display a monolithic β phase microstructure and exhibit high maximum strength (∼5 GPa) as well as superior plasticity (∼80%, without failure even though the maximum load limit is reached at the load capacity of 100 kN). Deformation mechanism is anticipated on the basis of twins and slip band patterns obtained in the vicinity of micro-hardness indentation, B o ¯ - M d ¯ phase stability map and e / a ¯ - Δ r ¯ diagram. Moreover, shear band analyses on deformed samples are also conducted. Additionally, the evaluation of wear resistance indices (H/E and H3/Eeff2) are employed in the present work. Amongst all the investigated alloys, Ti-25Nb-1Sn-2Cr shows the lowest Young’s modulus (66 GPa) with the highest values of yield strength, hardness and wear resistance indices.

Subgroup J Avian leukosis virus (ALV-J) is an important pathogen of poultry tumor diseases. Since its discovery, it has caused significant economic losses to the poultry industry. Thus, the rapid detection of molecular level with strong specificity is particularly important whether poultry are infected with ALV-J. In this study, we designed primers and probe for real-time fluorescent reverse-transcription recombinase-aided amplification assay (RT-RAA) based on the ALV-J gp85 sequence. We had established a real-time fluorescent RT-RAA method and confirmed this system by verifying the specificity and sensitivity of the primers and probe. In addition, repeatability tests and clinical sample regression tests were used for preliminary evaluation of this detection method. The sensitivity of established method was about 10

Laves phase alloys are promising materials for several structural applications, but the extreme brittleness is the predominant shortcoming of a Laves matrix. One potential solution to overcome this shortcoming is to alloy Laves matrix with some soft matrix. A group of Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) alloys was cast with an aim to improve deformation in Laves alloy compositions. The phase and microstructure analyses reveal dual phase matrices, including a β phase and a C14 type Laves phase in the investigated alloys. The mechanical properties such as yield strength, hardness and plastic strain for the investigated alloys are found to be significantly sensitive to volume fraction of the Laves phase. Ti-35Zr-5Fe shows impressive ultimate compressive strength (~1.7 GPa), yield strength (1138 MPa) and large plastic strain (23.2 %). The fracture mechanisms are dependent on the microstructure of the alloys. Additionally, the work-hardening ability of the investigated alloys have also been evaluated based on the analyses of slip band patterns formed around the micro-hardness indentations. Notably, the extreme brittleness is not encountered in all the Ti-35Zr-5Fe-xMn alloys and all exhibit very good compressive elongation including the maximum (32.5 %) in Ti-35Zr-5Fe. Keywords: Laves phase, Titanium alloy, Deformation, Mechanical strength, Fracture analysis, Shear band

The influence of 0.42 and 0.72 wt.% Zn on the intergranular corrosion (IGC) of Al–3.7Cu–1.15Li–0.5Mg and Al–2.7Cu–1.7Li–0.3Mg alloys (representing different Cu/Li ratios) was investigated. IGC dependence on ageing time was studied and a primitive IGC diagram established. With ageing, the potential of the Al –x Cu –y Li alloys lowered due to precipitation, accompanied by grain boundary precipitate coarsening. Concomitantly, corrosion mode evolved with ageing from pitting and local IGC (early ageing), general IGC (under-aged), local IGC (near peak-aged) and pitting (over-aged). Of key interest is that Zn additions remarkably decreased the IGC sensitivity of the Al–2.7Cu–1.7Li–0.3Mg.

In order to achieve an effective balance between plasticity and strength, a group of Ti-26Nb-xZr-yMn (x = 4, 7, 10 wt% and y = 3, 5 wt%) alloys were designed to evaluate the effects of Mn and Zr on the microstructures, mechanical properties and strengthening effects of the Ti Nb system. All the investigated alloys illustrate a monolithic β phase in their microstructure and they all possess substantial true plasticity (~160%) and true maximum strength (~ 950 MPa) without fracture during the compression tests within the load capacity of 100 kN. The contribution of solid-solution, grain-boundary and dislocation strengthening mechanisms have been evaluated using the strengthening model for β Ti alloys for all the investigated alloys. Among the investigated alloys, Ti-26Nb-4Zr-5Mn demonstrates the highest true yield strength (654 MPa), dislocation density (2.45 × 1015 m−2) and hardness (242 HV) along with improved strain hardening ability in terms of strain hardening indices (0.42 and 0.09). Furthermore, based on the superior mechanical properties among the investigated alloys, the electrochemical performance of Ti-26Nb-4Zr-3Mn and Ti-26Nb-4Zr-5Mn have also been analyzed in this work. The electrochemical measurements show that both alloys have almost similar corrosion potential and corrosion current density in simulated body fluid, i.e., −0.45 V and 0.838 nA/cm2 for Ti-26Nb-4Zr-3Mn, −0.48 V and 0.839 nA/cm2 for Ti-26Nb-4Zr-5Mn, respectively.

A series of Ti-25Nb-8Zr-xCr (x = 0, 2, 4, 6, 8 wt%) alloys were designed based on DV-Xα cluster method and e/a¯-Δr¯ diagram with an anticipation to obtain high plasticity and significant strain hardening. The designed alloys were produced through cold crucible levitation melting technique in order to effectively investigate their microstructures and mechanical properties. The addition of Cr significantly enhances the β stability in the microstructures of the Ti-25Nb-8Zr-xCr alloys. Both yield strength and hardness of the studied alloys increase due to the effect of solid-solution strengthening. By constrast, the plasticity, maximum strength and strain hardening rate are influenced by the β stability as well as the distinct deformation mechanisms. None of the alloys comprising Cr fail up to 100 kN (the load capacity used) and all show impressive plasticity (~75%) and superior maximum compressive strength (~4.5 GPa) at 100 kN. Moreover, the deformation bands, which are found around the hardness indentations, are analyzed for all the investigated alloys. The fracture behaviors of the Ti-25Nb-8Zr-xCr alloys are also studied to observe the characteristics related to crack propagation, plastic deformation and the formation of shear bands. Keywords: Titanium alloy, Plasticity, Strength, Strain hardening, Deformation band, Shear band

Microstructural changes following oxidation at high temperatures of a complex coating or alloy can significantly influence its properties. This paper investigates possible solutions that can accurately model alloy microstructures that result from such a process in a cobalt-rich CoNiCrAlReY bond coat alloy system. Four different alloys with varying aluminum content were studied after heat treatments at 1000 °C or 1150 °C. SEM, EPMA and XRD were used to characterize the alloy microstructure, and hardness testing was performed to determine the role of microstructure on mechanical properties. Experimental microstructures were modeled using two databases of Thermo-Calc, namely TTNI8 and SSOL5. Effects of Al content on phase changes and materials properties were quantitatively investigated. Data showed that a 1 wt. % increase of Al in the alloy caused an 8% increase in the beta phase, and a Cr and Re rich sigma phase precipitated preferentially at high Al concentrations. In addition, alloy hardness was found to increase by 4 and 81%, respectively, with a 10% increase in the beta and sigma phases. Modeled results using the TTNI8 database showed excellent agreement with experimental observations, but the SSOL5 database produced erroneous information.

Chemical mechanical planarization (CMP) is widely used to planarize semiconductor wafers and smooth the wafer surface. In CMP, a diamond disc conditioner is employed to condition (or dress) a polishing pad to restore the pad planarity and surface roughness. In this paper, a surface element method is proposed to develop a mathematic model to predict the pad surface shape resulted from diamond disc conditioning. The developed model is then validated by published experimental data. Results show that the model effectively simulates diamond disc conditioning and predicts the pad surface shape.

The continuous-wave high-efficiency laser emission from Nd:YVO4 at the fundamental wavelength of 1342 nm and its 671 nm second harmonic obtained by intra-cavity frequency doubling in an LBO nonlinear crystal are investigated under pumping by diode laser at 880 nm (on the 4F3/2→4I13/2 transition). The end-pumped Nd:YVO4 crystal yielded a continuous-wave output power of 9.6 W at 1342 nm for 18.9 W of absorbed pump power. The slope efficiency measured with respect to the absorbed pump power is 60%. An output of 5.5 W at 671 nm was obtained by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 29%. Comparative results obtained for the pump with a diode laser at 808 nm (on the 4F5/2→4I13/2 transition) are given in order to prove the advantages of the 880 nm wavelength pumping.

Silicon wafers are the fundamental building blocks for most integrated circuits. The lapping-based manufacturing method currently used to manufacture the majority of silicon wafers will not be able to meet the ever-increasing demand for flatter wafers and lower prices. A grinding-based manufacturing method has been investigated experimentally to demonstrate its potential to manufacture flat silicon wafers at a lower cost. It has been demonstrated that the site flatness on the ground wafers (except for a few sites at the wafer center) could meet the stringent specifications for future silicon wafers. This paper, as a follow up, addresses one of the reasons for the poor flatness at the wafer center: central dimples on ground wafers. A finite element model is developed to illustrate the generation mechanisms of central dimples. Then, effects of influencing factors (including Young's modulus and Poisson's ratio of the grinding wheel segment, dimensions of the wheel segment, grinding force, and chuck shape) on the central dimple sizes are studied. Pilot experimental results will be presented to substantiate the predicted results from the finite element model. This provides practical guidance to eliminate or reduce central dimples on ground wafers.

Among the III–V semiconductors, InSb has the smallest electron effective mass and the largest g-factor. We make use of these properties to explore some aspects of electron spin in InSb quantum wells with far-infrared magneto-spectroscopy. We observe the clear signature of spin-resolved cyclotron resonance caused by the non-parabolicity of the conduction band. We observe avoided-level crossings at magnetic fields where Landau levels of the same spin are predicted to intersect. We also study electron spin resonance in the far infrared over a wide range of magnetic field. In samples with symmetrically designed quantum wells we find cyclotron masses and observed g-factors in good agreement with a Pidgeon–Brown analysis adapted to the two-dimensional band structure. However, the spin splitting approaches ∼3 meV as the magnetic field approaches zero in samples intentionally asymmetrically doped.

The continuous-wave high-efficiency laser emission of Nd:GdVO 4 at the second-harmonic of 456 nm obtained by intracavity frequency doubling with an BiB 3 O 6 (BiBO) nonlinear crystal is investigated under pumping by diode laser at 880 nm into emitting level 4 F 3/2 . About 3.8 W at 456 nm with M 2 = 1.4 was obtained from a 5 mm-thick 0.4 at.% Nd:GdVO 4 laser medium and a 12 mm-long BiBO nonlinear crystal in a Z -type cavity for 13.9 W absorbed pump power. An optical-to-optical efficiency with respect to the absorbed pump power was 0.274. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing 4 F 5 / 2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.

Highly efficient 1341 nm continuous-wave laser under 880 nm diode laser pumping in Nd:GdVO 4 crystal is reported. Comparative results obtained by the traditional pumping at 808 nm were presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power under 880 nm pumping was 34.9% higher and 12.6% lower than those of 808 nm pumping. A high slope efficiency of 49.1% was achieved under 880 nm pumping, with an optical-to-optical conversion efficiency of 41.7%.

This paper presents the transonic higher-order approximation method. This method is applicable to the transonic flow (in subsonic and low-supersonic free streams) over high and low aspect ratio rigid, flexible thin, and thick wings with or without control deflections. Typical computed results and their comparisons with wind tunnel test data are presented.

The activities of Hg in {(1 − y)Hg + y(1 − t)Bi + ytSn} have been measured at 600 K using a high-temperature isopiestic technique. Each entire isopiestic curve of mercury was determined by only one experiment. The activities of Bi and Sn were calculated using an analytical procedure from the ternary isoactivity results and the selected thermodynamic values for the binary sub-systems {(1 − y)Hg + yBi}, {(1 − y)Hg + ySn}, and {(1 − t)Bi + tSn}. The results approximately fit the partial ideal-solution model proposed previously.