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Highlights: [•] The Re1−xRu x B2 is more stable than that of Ru1−xRe x B2. [•] The Re0.5Ru0.5B2 is the most stable structure. [•] The elastic modulus of this binary alloy borides are related to Re concentration. [•] This binary alloy borides exhibit brittle behavior. [•] The B/G ratio of Re0.75Ru0.25B2 (1.23) is lower than that of ReB2 (1.29). [ABSTRACT FROM AUTHOR]

Highlights: [•] U-doped system with cubic structure is more stable than the monoclinic structure. [•] The elastic modulus of cubic structure is higher than the monoclinic structure. [•] U-doped weakens the resistance to shear deformation of ZrO2. [•] U-doped enhances the resistance to shape deformation for monoclinic structure. [ABSTRACT FROM AUTHOR]

Compared to experiment, the adsorption energies, bonding properties, and electronic structure of two different Al2O3/B4C bridge sites with seven different Al2O3 surfaces are investigated by ab initio periodic density functional theory. The Al2O3/B4C ceramic sintered in Ar is synthesized and measured by XRD and TEM. The calculated results reveal that the densification of O_bridge site of Al2O3/B4C surface is better than that of Al_bridge. The Al2O3 (113)/B4C with O_bridge is the most favorable and stable. The electronic structure shows that the electron hybridization exists between Al, O atoms and C, B atoms. The results indicate that the calculated results are in good agreement with the experiment. [ABSTRACT FROM AUTHOR]

Abstract: Al2O3–14wt%B4C composites with 0–1wt% C addition were sintered in Ar at 1550–1650°C. The influence of the C additive on the B loss, densification behavior, and microstructure of the Al2O3–B4C composites were investigated. The results show that there are B2O3, H3BO3 and Al18B4O33 exist between Al2O3 and B4C interface, which result in B loss because of B2O3''s high vapor tension at above 1500°C. The presence of Al18B4O33 grains formed by chemical reaction of Al2O3 with surface oxides on B4C inhibit the densification of pellets by reducing the specific free surface energy of the Al2O3. However, the added C eliminates those oxides to reduce B loss because of its higher activity than B4C, and it also coarsens Al2O3 grain although the density of pellets is decreased by gas products. [Copyright &y& Elsevier]

We have developed a simple method to fabricate nanoscale masks by using self-assembly Ni clusters formed through a rapid thermal annealing (RTA) process. The density and dimensions of the Ni nano-masks could be precisely controlled. The nano-masks were successfully applied to GaN-based light-emitting diodes (LEDs) with nano-roughened surface, GaN nanorods, and GaN-based nanorod LEDs to enhance light output power or change structure properties. The GaN-based LED with nano-roughened surface by Ni nano-masks and excimer laser etching has increased 55% light output at 20 mA when compared to that without the nano-roughened process. The GaN nanorods fabricated by the Ni nano-masks and ICP-RIE dry etching showed 3.5 times over the as-grown sample in photoluminescence (PL) intensity. The GaN-based nanorod LEDs assisted by photo-enhanced chemical (PEC) wet oxidation process were also demonstrated. The electroluminescence (EL) intensity of the GaN-based nanorod LED with PEC was about 1.76 times that of the as-grown LED. The fabrication, structure properties, physical features, and the optical and electrical properties of the fabricated devices will be discussed. [ABSTRACT FROM PUBLISHER]

To check the doping mechanism of trivalent ion doping in PbWO4 (PWO) and verify the formation of dipoles [2MPb3+–VPb], the researches on an investigation of tetravalent ion (Th4+, Zr4+) doped PWO was conducted by dielectric loss spectroscopy, thermoluminescence and optical absorption spectroscopy. The doping mechanism of tetravalent ion doping is similar to that of trivalent ion doping, while the dipole defects should be formed more easily due to the convenience for the two defects VPb and MPb4+ to get close to each other. However, in the case of Zr4+ doping, Zr was found to enter interstitial sites because of its small ionic radius, with the introduced charges compensated by VPb far away and hence does not exert an obvious influence on the performance of this material. Thus, no dielectric relaxation was found in the DS (dielectric spectra) experiment. [Copyright &y& Elsevier]

An InGaN-GaN thin-film vertical-type light-emitting diode with a two-dimensional photonic crystal (PC) on the emitting surface and a TiO-SiO omnidirectional reflector on the bottom was fabricated. The device was investigated by performing a series of experiments and numerical computations. Electroluminescence measurement revealed a strong extraction enhancement in the vertical direction at 433-nm wavelength. The emission spectrum of the light was found to be strongly modified by the PC to have a significantly narrow linewidth of 5 nm. Our experimental results were in accord with those obtained from our numerical findings. [ABSTRACT FROM PUBLISHER]

We have designed and fabricated a new type of GaN-based thin-film vertical-injection light-emitting diode (LED) with TiO2-SiO 2 omnidirectional reflector (ODR) and n-GaN roughness. The associated ODR designed for LED operation wavelength at 455 nm was integrated with patterned conducting channels for the purpose of vertical current spreading. With the help of laser lift-off and photo-electrochemical etching technologies, at a driving current of 350 mA and with chip size of 1 mm times 1 mm, the light-output power and the external quantum efficiency of our thin-film LED with TiO2-SiO2 ODR reached 330 mW and 26.7%. The result demonstrated 18% power enhancement when compared with the results from the thin-film LED with Al reflector replace [ABSTRACT FROM PUBLISHER]

Enhancement of light extraction of GaN-based flip-chip indium-tin-oxide light-emitting diodes (FC ITO LEDs) with an omnidirectional reflector (ODR) is presented. The ODR consisting of alternating layers of TiO2 and SiO2 is designed to possess a complete photonic bandgap within the blue region of interest, and it is fabricated by E-beam deposition. At a driving current of 300mA and a chip size of 1 mmtimes1 mm, the light output power of the FC ITO LEDs with the ODR reaches 156 mW. This is an enhancement of 31% when compared with the same device with an Al mirror instead. Furthermore, by examining the radiation patterns, the FC ITO LED with the ODR shows stronger enhancement around the vertical direction. Our work offers promising potential for enhancing output powers of commercial light-emitting devices [ABSTRACT FROM PUBLISHER]

Presents information on a study which developed a method for in-situ observation of magnetic domain structures in the presence of an applied magnetic field by using a magnetic force microscope. Lithographic technique for the fabrication of the micro-structures; Scanning probe microscopy; Results and conclusion.

Although a slope may have numerous potential slip surfaces, its failure probability is often governed by several representative slip surfaces (RSSs). Previous efforts mainly focus on the identification of circular RSSs based on limit equilibrium methods. In this paper, a method is suggested to identify RSSs of arbitrary shape based on the shear strength reduction method. Monte Carlo simulation is used to generate a large number potential slip surfaces. The RSSs are identified through analyzing the failure domains represented by these samples. A kriging-based response surface model is employed to enhance the computational efficiency. These examples shows that the RSSs may not always be circular, and that the suggested method can effectively locate the RSSs without making prior assumptions about the shape of the slip surfaces. For the examples investigated, the system failure probabilities computed based on the shear strength reduction method are comparable to, but not the same as those computed based on the limit equilibrium methods. The suggested method significantly extends our capability for identifying non-circular RSSs and hence probabilistic slope stability analysis involving non-circular slip surfaces. [ABSTRACT FROM AUTHOR]

The site investigation (SI) is important to reduce the uncertainty of the slope soil properties. Its effectiveness is highly related to the planning of an SI program such as borehole layout. It is thus tempting to assess the potential uncertainty reduction of an SI program. This paper presents a method to assess the expected benefit (EB) of an SI program for slope. The cost saving of reliability-based design under unknown observations is considered. Compared with the previous methods, this method can take into consideration the uncertainty of the scale of fluctuation (SOF) of the soil, and the knowledge about the consequence of slope failure is not required. A subset logistic regression method is suggested to approximate the probability of slope failure. The SI program can be optimized by selecting the borehole layout with the maximal EB. For the example in this paper, it is found that the EB of an SI program depends on the SOF of the soil. If the uncertainty in the SOF is not considered, the EB may be underestimated or overestimated. The proposed method provides a practical and efficient way to assess the effectiveness of SI program for design of slopes. • A reliability-based method to assess site investigation program is proposed. • The uncertainty of scale of fluctuation is systematically considered. • A method of subset logistic regression is developed to check the feasible design. • The site investigation program can be optimized by maximizing the expected benefit. [ABSTRACT FROM AUTHOR]

Abstract: This study addresses the influence of elevated pressures up to 1.6MPa on the flame geometry and the flickering behavior of laminar diffusion flames and particular attention has been paid to the effect of fuel variability. It has been observed that the flame properties are very sensitive to the fuel type and pressure. The shape of the flame was observed to change dramatically with pressure. When the pressure increases, the visible flame diameter decreases. The height of a flame increases first with pressure and then reduces with the further increase of pressure. The cross-sectional area of the flame (A cs) shows an average inverse dependence on pressure to the power of n (A cs ∝ P−n ), where n =0.8±0.2 for ethylene flame, n =0.5±0.1 for methane flame and n =0.6±0.1 for propane flame. It was observed that the region of stable combustion was markedly reduced as pressure was increased. High speed imaging and power spectra of the flame chemiluminescence reveal that an ethylene flame flickers with at least three dominant modes, each with corresponding harmonics at elevated pressures. In contrast methane flames flicker with one dominant frequency and as many as six harmonic modes at elevated pressures. [Copyright &y& Elsevier]

Site investigation is widely used for uncertainty reduction and design improvement in slope engineering. Before the site investigation is implemented, it is important to assess and compare the effectiveness of different site investigation programs. In this paper, an efficient method for analyzing the effectiveness of a site investigation program for slope stability assessment through value of information analysis is proposed. In this method, a logistic regression model is developed to approximate the relationship between failure probability of the slope and the site investigation data, through which the evaluation of posterior distribution and slope reliability analyses are both avoided. The suggested method is illustrated and verified with an example. For the example studied in this paper, the number of slope stability analyses required is only 1% of that reported in the literature. The suggested method can be used to study the effects of locations of the boreholes, the number of boreholes, and the depth of boreholes on the effectiveness of a site investigation program. [ABSTRACT FROM AUTHOR]

This paper suggests a new set of analytical solutions for predicting the effect of grouting on ground and shield tunnel behaviour as a consequence of steady water inflow into a tunnel in saturated clay. These solutions allow the effects of the tunnel lining and grouting material to be considered on the basis of their relative permeability to the surrounding soil. Moreover, the equivalent permeability of the tunnel lining can be derived based on the water inflow rate, which is commonly assumed to be proportional to the soil permeability in a typical analysis. A comparison of the results of analytical and numerical simulations indicates that the solutions are sufficiently accurate for tunnel applications. The effect of grouting material on the tunnel-leakage-induced seepage field, ground and tunnel settlements, internal forces and tunnel convergence of the shield tunnel are examined with the verified solutions. Based on the analytical results, the effect of grouting material on the tunnel leakage appears to depend on the permeability of the tunnel lining. Thus, a dimensionless parameter RP slg integrating the permeability and geometry of the tunnel lining and grouting material is proposed to quantitatively describe the effect of the grouting material on tunnel leakage. Using RP slg , the effect of the grouting material on tunnel leakage can be easily derived. Indeed, the analytical results show that tunnel leakage produces significant ground and tunnel settlement. The grouting can clearly reduce the effect of tunnel leakage on tunnel and ground settlement when the relative permeability of the grouting material and soil k g / k s is less than 0.01. Moreover, the increase in the tunnel-leakage-induced bending moment and the decrease in hoop thrust are generally small but this may increase the permeability of the tunnel joints. The leakage-induced tunnel convergence is small and is therefore unlikely to degrade the serviceability or safety of a tunnel. [ABSTRACT FROM AUTHOR]

Semi-empirical models used for liquefaction potential evaluation are often developed based on lumping data from different regions around the world. The accuracy of a semi-empirical model developed in such a way may vary from one region to another, which has been seldom studied previously. Thus, in this paper, a probabilistic method is suggested to characterize the inter-region variability of the model bias factor of a semi-empirical model for liquefaction potential evaluation. As an illustration, the proposed approach is used to characterize the inter-region variability of the model bias factor of the Robertson and Wride model (called RW model for short herein). It is found that substantial inter-region variability exists in the model bias factor of the RW model. For a region not in the calibration database, the uncertainty associated with the model bias factor is significantly larger than that of a region in the calibration database. For regions in the calibration database, the uncertainty associated with the model bias factor in a region also changes with the amount and the type of the calibration data available in that region. It is thus important to collect region-specific performance data for model calibration to achieve accurate liquefaction potential evaluation. For ease of practical application, equations are provided for estimating the liquefaction probability based on the factor of safety (FOS) computed with the RW model for different regions. The suggested method can also be used to characterize the inter-region variability of other semi-empirical models and to derive region-specific relationships between FOS and liquefaction probability for these models. [ABSTRACT FROM AUTHOR]

Abstract: We evidenced an early-stage ordering (ESO) in Fe51Pt49 film before the appearance of superlattice diffraction (long-range-order, LRO) using 40-nm-thick films prepared by magnetron sputtering onto quartz substrate. The appearance of L10 phase for samples deposited at substrate temperatures (T s) 400°C and higher was verified by X-ray diffraction. Surface roughness of Fe51Pt49 films, obtained via X-ray specular reflectivity with computational fitting, increases from 3.8 to 11Å as T s is increased from 25 to 275°C. As further increase of T s to 375°C, the roughness drops to 3.2Å and then increases again to 38Å with T s up to 700°C. Measurement on residual strain demonstrates that it is initially compressive at T s<400°C. Thereafter the strain transfers to a tensile one and increases in magnitude as increasing T s up to 700°C corresponding to LRO transformation. Local atomic rearrangement is observed for samples deposited at T s>250°C by using extended X-ray absorption fine structure. Coercivity of films increases from 10 to 460Oe as T s increase from 25 to 375°C (ESO) and then from 460 to 10,700Oe with T s 375–700°C (normal LRO). The worked out quantitative estimation of ESO engages with that of LRO before T s 400°C. [Copyright &y& Elsevier]

Abstract: Using microfluidics for protein crystallization gives numerous advantages compared with classical techniques, as much reduced protein consumption, improved control accuracy and high parallelism. We propose here novel systems for the screening of protein crystallization conditions using microfluidic devices. Lysozyme was used as protein model for crystallization trials and sodium chloride as precipitating agent. Single crystals of lysozyme, large enough for X-ray diffraction studies, were rapidly formed into the 20nl chambers of the microfluidic devices. A systematic and comparative study is now under development to better understand how to control the speed and efficiency of crystallization as well as the size of the crystals for both vapor diffusion and batch techniques. [Copyright &y& Elsevier]