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Phase change material (PCM) based thermal energy storage (TES) is an important solution to the waste of heat and intermittency of new energy sources. However, the thermal conductivity of most PCMs is low, which severely affects the thermal energy storage performance. Oscillation of the tube bundles in a TES unit can intensify the convection of liquid PCM and, therefore, enhance heat transfer. However, the energy storage performance of bundled-tube TES systems in response to oscillation at different amplitudes and frequencies has not been well understood yet, and the optimum time to apply the oscillation during phase transition remains unexplored. To address this issue, this present study was carried out. First, the melting behaviour of PCM with oscillation starting at different times was investigated. Then, the influences of oscillation frequency and amplitude on the melting performance were explored. Finally, the solidification behaviour of PCM with oscillation starting at different times was examined. Results show that the oscillation can accelerate the phase transition process by enhancing convective heat transfer. Compared to the case without oscillation, the complete melting and solidification times are reduced by 8.2 and 6.7% for the case with oscillation starting at 200 s, respectively. The effect of oscillation frequency on the melting enhancement is negligible, while the oscillation amplitude has an important effect on the melting enhancement. [ABSTRACT FROM AUTHOR]

Super-high dielectric constant (k) AlOx/TiOy nanolaminates (ATO NLs) are deposited by an atomic layer deposition technique for application in next-generation electronics. Individual multilayers with uniform thicknesses are formed for the ATO NLs. With an increase in AlOx content in each ATO sublayer, the shape of the Raman spectrum has a tendency to approach that of a single AlOx layer. The effects of ATO NL deposition conditions on the electrical properties of the metal/ATO NL/metal capacitors were investigated. A lower deposition temperature, thicker ATO NL, and lower TiOy content in each ATO sublayer can lead to a lower leakage current and smaller loss tangent at 1 kHz for the capacitors. A higher deposition temperature, larger number of ATO interfaces, and higher TiOy content in each ATO sublayer are important for obtaining higher k values for the ATO NLs. With an increase in resistance in the capacitors, the ATO NLs vary from semiconductors to insulators and their k values have a tendency to decrease. For most of the capacitors, the capacitances reduce with increments in absolute measurement voltage. There are semi-circular shapes for the impedance spectra of the capacitors. By fitting them with the equivalent circuit, it is observed that with the increase in absolute voltage, both parallel resistance and capacitance decrease. The variation in the capacitance is explained well by a novel double-Schottky electrode contact model. The formation of super-high k values for the semiconducting ATO NLs is possibly attributed to the accumulation of charges. [ABSTRACT FROM AUTHOR]

The impact of a chief executive officer's (CEO's) functional experience on firm performance has gained the attention of many scholars. However, the measurement of functional experience is rarely disclosed in the public database. Few studies have been conducted on the comprehensive functional experience of CEOs. This paper used the upper echelons theory and obtained deep-level curricula vitae (CVs) data through the named entity recognition technique. First, we mined 15 consecutive years of CEOs' CVs from 2006 to 2020 from Chinese listed companies. Second, we extracted information throughout their careers and automatically classified their functional hierarchy. Finally, we constructed breadth (functional breadth: functional experience richness) and depth (functional depth: average tenure and the hierarchy of function) for empirical analysis. We found that a CEO's breadth is significantly negatively related to firm performance, and the quadratic term is significantly positive. A CEO's depth is significantly positively related to firm performance, and the quadratic term is significantly negative. The research results indicate a u-shaped relationship between a CEO's breadth and firm performance and an inverted u-shaped relationship between their depth and firm performance. The study's findings extend the literature on factors influencing firm performance and CEOs' functional experience. The study expands from the horizontal macro to the vertical micro level, providing new evidence to support the recruitment and selection of high-level corporate talent. [ABSTRACT FROM AUTHOR]

The ohmic contact resistance (${R}_{C}$), surface resistance (${R}_{S}$), and channel resistance (${R}_{\text {CH}}$) of hydrogen-terminated diamond (H-diamond) MOSFETs were investigated in this study. Planar-type and T-type H-diamond MOSFETs were employed to analyze them. Because no interspaces exist between the source–drain and gate electrodes for the T-type H-diamond MOSFETs, then ${R}_{S}$ is zero. Both planar-type and T-type MOSFETs show low leakage current densities and good operations. By considering the relationships between the total resistance (${R}_{ \mathrm{\scriptscriptstyle ON}}$) and 1/ $\vert $ gate voltage-threshold voltage $\vert $ , ${R}_{C}$ and ${R}_{\text {CH}}$ for the T-type H-diamond MOSFET at a gate voltage of −10.0 V are determined to be 13.8 and 21.8 $\Omega \cdot $ mm, respectively. As ${R}_{C}$ for both MOSFETs is the same, ${R}_{S}$ and ${R}_{\text {CH}}$ for the planar-type H-diamond MOSFET are deduced to be 90.0 and 15.8 $\Omega \cdot $ mm, respectively. ${R}_{S}$ accounts for 75.3% of ${R}_{ \mathrm{\scriptscriptstyle ON}}$ for the planar-type H-diamond MOSFET, which is the main reason for its lower drain current and extrinsic transconductance than those of the T-type MOSFET. Although ${R}_{S}$ is suppressed for the T-type H-diamond MOSFET, ${R}_{C}$ occupies 38.8% of ${R}_{ \mathrm{\scriptscriptstyle ON}}$. To further improve the performance of the H-diamond MOSFETs, it is important to eliminate ${R}_{S}$ and decrease ${R}_{C}$ to further improve the electrical properties of the H-diamond MOSFETs. [ABSTRACT FROM AUTHOR]

• A novel porous structure based on truncated cuboctahedron is proposed. • The novel porous structure better enhances PCM melting near the porous cell corners. • A critical porosity exists to determine the enhancement advantages of two different porous structures. • The critical porosity is decreased with the increase of pore density. Metallic porous structure is a prevailing heat transfer enhancer for the melting of phase change material (PCM), while the effect of the structure on the enhancement performance is yet to be understood. In this work, a pore-scale numerical study on PCM melting embedded in a truncated cuboctahedron porous structure, referred as TCD metal foam, was performed. The solid–liquid interface, temperature and the variation of liquid fraction were analyzed and compared with those with the tetrakaidecahedron porous structure, referred as TKD metal foam. The effects of natural convection, porosity, pore density and heating temperature are explored. It is found the natural convection shortens the PCM melting time by about 7 % with the considered porosity range and thus cannot be ignored. Results also show that the TCD metal foam better enhances PCM melting near the porous cell corners compared to the TKD metal foam. Further analysis shows the TCD metal foam can better enhance melting at the former stage due to the larger surface area, while the TKD metal foam can better enhance melting at the later stage due to the thicker metallic ligaments. With essentially the same melting time at ɛ = 0.941, the half-melting takes 17.2 % of the complete melting time for TCD metal foam and 20.3 % of the complete melting time for TKD metal foam. A critical porosity value exists when comparing the enhancement performance of these two metal foams, below which the better melting enhancement is shifted from the case with TCD metal foam to the case with TKD one. The critical porosities are 0.941, 0.923 and 0.899 at the pore densities of 10, 20 and 30 PPI respectively. [ABSTRACT FROM AUTHOR]

Boron-doped diamond (B-diamond) metal–oxide–semiconductor (MOS) capacitor and MOS field-effect transistor (MOSFET) are fabricated on a flat diamond epitaxial layer. Their electrical properties and thermal stabilities after annealing at 500 °C are investigated. Annealing makes the leakage current density of the B-diamond MOS capacitor increase slightly. There is a larger stretch-out for the capacitance-voltage curve in the depletion region after annealing than that before annealing. The drain-current maxima for the as-fabricated and 500 °C-annealed MOSFETs are obtained as −0.49 and −0.60 mA/mm, respectively. Extrinsic transconductance maxima are 18.7 and $21.4~\mu \text{S}$ /mm, respectively. These obtained values are considerably larger than those obtained by the previously reported B-diamond MOSFETs. [ABSTRACT FROM AUTHOR]

The mechanical property of roof is critically important for underground coal mining activities. The existence of hard roof that cannot cave naturally after coal extraction results in an unconsolidated goaf with large voids, and the sudden failure of this type of roof in uncontrolled manner will cause server windblast or rockburst hazard. To address this hazard, pre-existing fractures are created in roof by hydraulic fracturing or blasting to weaken the hard roof and promote its natural caving. The effectiveness of these roof weakening techniques is highly dependent on the geometry of pre-conditioned fractures and its impact on the mechanical behaviour of combined roof-coal strata, which has not been well-explored yet. Therefore, 21 groups of uniaxial compression testing on combined rock-coal specimens with pre-existing cracks were carried out, and the effect of fracture length and angle on the mechanical properties and failure modes of combined rock-coal strata were investigated. It can be concluded that longer cracks and/or cracks with angle closer to 30° tend to have the following characteristics. (1) The more gentle the stress-strain curve of the combined coal and rock tends to be, the larger the decrease range of its elastic modulus, peak strength and peak strain, and the smaller the strain interval corresponding to the elastic-plastic stage. The results show that the artificial fracture weakens the mechanical properties of composite coal and accelerates the process from micro-crack to macro failure. (2) When the specimen enters the plastic stage, the acoustic emission jumps sharply; the cumulative number of micro-cracks and the cumulative energy released during the whole loading process gradually decrease, and the number of micro-cracks and the released energy at the moment of failure also decrease gradually. (3) The crack-initiating stress for combined coal-rock specimens gradually decreases via one of three typical modes: preferential crack initiation of coal, simultaneous crack initiation of combined coal-rock and preferential crack initiation of rock, which also matches with coal failure, rock-coal failure and rock failure in the combined specimens. Thus, to promote the continuous fracture of the roof under loading, the length and orientation of the pre-conditioned cracks must be controlled and optimised. [ABSTRACT FROM AUTHOR]

Here, thermal stabilities for Ohmic contact properties of Pt, Au, and Pd on the same hydrogen-terminated diamond (H-diamond) epitaxial layer are investigated. A long-term annealing process is performed with an annealing temperature and time of 400 °C and 8 h, respectively. Before annealing, good Ohmic contact properties are observed for only two contacts of the Pt/H-diamond and Pd/H-diamond with specific contact resistivity (ρC) values of 2.7 × 10−3 Ω cm2 and 2.6 × 10−4 Ω cm2, respectively. After long-term annealing, all three contacts on the H-diamond show good Ohmic contact properties. The ρC values for the Pt/H-diamond and Au/H-diamond are 3.1 × 10−2 Ω cm2 and 4.2 × 10−4 Ω cm2, respectively. They are higher than that of the Pd/H-diamond (1.1 × 10−4 Ω cm2). Therefore, low ρC and good thermal stability for the Pd/H-diamond are achieved. This is meaningful for pushing forward the development of H-diamond-based electronic devices for high-temperature applications. [ABSTRACT FROM AUTHOR]

In this article, we report the fabrication and characterization of boron-doped diamond (B-diamond) Schottky diodes and MESFETs. Effects of annealing at 573–973 K on the electrical properties of these devices are investigated. Current density maximum for the as-fabricated Schottky diode is 0.05 A/cm2 at a gate voltage of −10.0 V. Annealing at 673 and 973 K makes it increase first to 0.70 A/cm2 and decrease lately to 0.07 A/cm2, respectively. ON/OFF ratios for the as-fabricated B-diamond Schottky diode exceed 4.5 × 108 at the OFF-voltage (VOFF) of 0 V and 3.2 × 106 at VOFF = 42.0 V. For the annealed Schottky diode, the ON/OFF ratios are higher than 1.7 × 106 at VOFF < 6.0} V. Ideality factor and barrier height for Au/Pt bilayer gates on the B-diamond channel layer range from 1.05 to 1.78 and from 1.24 to 1.56 eV, respectively. All three B-diamond MESFETs with the gate lengths of 12.0, 7.0, and 4.3 μm, respectively, operate with p-type channel characteristics. The drain current maxima for the as-fabricated MESFETs are −0.11, −0.16, and −0.39 mA/mm. After annealing at 773 K, these values increase to −0.17, −0.24, and −0.55 mA/mm. Annealing at 773 K also increases the extrinsic transconductance maxima for the three MESFETs from 11.1, 11.0, and 10.4μS/mm to 18.6, 16.2, and 14.4 μS/mm, respectively. [ABSTRACT FROM AUTHOR]

The employment of annular fins and longitudinal fins in latent heat thermal energy storage unit can significantly improve its thermal performance. However, the annular fins can greatly suppress the convection and longitudinal fins lead to severe non-uniform melting. To address this issue, three different types of combinational fins were proposed and applied in a vertical shell-tube storage unit in this study. The numerical model was first built with the adoption of enthalpy-porosity method. The simulation results were then verified with experimental data. Results showed that combinational fins leads to faster melting thorough enhancing both natural convection and conduction compared with only longitudinal or annular fins. This advantage in melting enhancement is even greater with the increase of fin volume. Moreover, the enhancement effect of combinational fins is better with the same longitudinal and annular fins volume and a higher longitudinal fin at the same longitudinal fin volume. The optimum combinational fins in present work has a melting time reduction of 31.0% and 21.2% compared with only longitudinal and annular fins, respectively. The results can provide important reference for the fins design in vertical shell-tube thermal energy storage units. [ABSTRACT FROM AUTHOR]

• T-shaped fin can enhance heat conduction and convection of PCM at the bottom region. • The horizontally and vertically arranged T-shaped fins outperforms other designs. • T-shaped fins reduce about 1/3 of melting time regardless of HTF temperature and fin volume. • A length ratio of vertical to horizontal portion greater than 1.0 can better enhance the melting performance. Enhancing the melting performance of phase change material (PCM) has always been an important issue in thermal energy storage. T-shaped fin has the potential to enhance melting as it has much larger heat transfer surface away from heat source compared to traditional longitudinal plate fin. However, its enhancement performance remains unexamined. This study examined the effect of T-shaped fins on PCM melting in a horizontal shell-and-tube storage unit. The melting enhancement performance of four T-shaped fins was compared with that of eight longitudinal plate fins which have the same total fin volume with T-shaped fins. The results showed that T-shaped fins can significantly enhance the melting process by shortening the complete melting time and improving the melting uniformity regardless of the heat transfer fluid (HTF) temperature. Compared to longitudinal plate fins, horizontally and vertically arranged T-shaped fins save 34.5% melting time, while the T-shaped fins having a 45° angle with horizontal direction save only 8% melting time. The lengths of the vertical and horizontal portions were further optimized to improve the melting performance. It is found T-shaped fins with a length ratio of vertical to horizontal portion greater than 1.0 can better enhance the melting performance, and a length ratio of 1.33 saves 47.1% melting time compared to the longitudinal plate fins. [ABSTRACT FROM AUTHOR]

A 3D multi-layer model with Gaussian profile was developed to investigate the thermal and mechanical behaviors of plasma sprayed NiCrBSi coatings during manufacturing. The coating growth was simulated by activating progressively the corresponding elements layer by layer, while the heat contributions of sprayed particles and of the impinging plasma jet were assumed as heat fluxes applied on the surface of the substrate or of the previously deposited layers. Thus, the temperature field within the specimen was predicted by considering thermal conduction inside the substrate/coating system, as well as thermal convection and radiation effects on the free surfaces of the sample. The specimen deformation and the stress status were then calculated by considering the transient temperature at each node as a thermal load. The simulated results indicate that quenching stresses dominate final residual stresses in the deposited coating: the final residual stresses are thus tensile within the coating. The simulated temperature variation and final deflection of the specimen agreed well with the corresponding measurements. It was also found that application of a low cooling rate results in lower residual stresses within the deposited coating. [ABSTRACT FROM AUTHOR]

High-performance β-Ga 2 O 3 -based Schottky barrier diodes (SBDs) and metal-semiconductor field-effect transistors (MESFETs) are fabricated on a non-delta-doped high doping level (>1018 cm−3) epitaxial wafer. Their electrical properties and stabilities after annealing at 200–400 °C are investigated. The ON/OFF ratios for all the SBDs are over 108. The ideality factors and Schottky barrier heights for the Au/β-Ga 2 O 3 SBDs with different annealing temperatures range from 1.5 to 2.5 and from 0.8 eV to 1.0 eV, respectively. There are obvious pinch-off and saturation characteristics for the β-Ga 2 O 3 MESFETs. The maximum drain current (I D, max) for the as-fabricated β-Ga 2 O 3 MESFET is 46.8 mA/mm at anode voltage of 2.0 V. They are much higher than the previously reported values of non-delta-doped and nanobelt β-Ga 2 O 3 MESFETs. Threshold voltages for the β-Ga 2 O 3 MESFETs shift to the negative direction with the increase of annealing temperature. This study is meaningful to push forward the development of β-Ga 2 O 3 -based electronic devices for practical applications. • High-performance β-Ga 2 O 3 -based Schottky diodes and metal-semiconductor field-effect transistors (MESFETs) are fabricated on a non-delta-doped high doping level (>1018 cm−3) epitaxial wafer. • Maximum drain current (I D, max) for the as-fabricated β-Ga 2 O 3 MESFET is 46.8 mA/mm at gate voltage of 2.0 V. They are much higher than the previously reported values of non-delta-doped and nanobelt β-Ga 2 O 3 MESFETs. [ABSTRACT FROM AUTHOR]

Plant litter quality considerably affects C accrual in soil organic matter (SOM). However, the chemical traits of litter that influence C distribution in SOM fractions, such as particulate organic matter (POM) and mineral-associated organic matter (MAOM), are not fully understood. Thus, we conducted a 150-day incubation experiment with litter addition (poplar leaves, roots, grasses grown under the canopy, and a mixture of these three litter types). We analyzed the organic C concentration in the POM and MAOM fractions and the stoichiometric ratios (C:N:P) of the soil and microbial biomass 50, 100, and 150 days after the initial litter addition. Microbial residue C (amino sugar biomarkers) in SOM fractions was registered at the end of decomposition. High-quality litter (i.e., leaf) increased MAOM-C accrual, and low-quality litter (i.e., root and grass) contributed more to POM-C accrual. The mixed litter addition accumulated more C in the SOM via high POM-C levels compared to single litter input, likely resulting from an antagonistic effect caused by different litter trait dissimilarity. Moreover, POM-C dynamics were dominated by litter chemical traits during litter decomposition, and MAOM-C was controlled mainly by microbial and soil stoichiometry. Furthermore, the contribution of microbial residue C to SOM (especially POM-C) was lower in the mixed litter than in the single litter. These findings highlight the direct or indirect impacts of litter types on the C dynamics of POM and MAOM, and demonstrate that litter diversity is conducive to C accumulation in SOM. [ABSTRACT FROM AUTHOR]

The crack susceptibility map of a ternary Al alloy system provides useful information about which alloy compositions are most susceptible to cracking and thus should be avoided by using a filler metal with a significantly different composition. In the present study the crack susceptibility maps of ternary Al alloy systems were calculated based on the maximum | dT/d(f S ) 1/2 | as an index for the crack susceptibility, where T is temperature and f S fraction solid. Due to the complexity associated with ternary alloy solidification, commercial thermodynamic software Pandat and Al database PanAluminum, instead of analytical equations, were used to calculate f S as a function of T and hence the maximum | dT/d(f S ) 1/2 | for ternary Al-Mg-Si, Al-Cu-Mg and Al-Cu-Si alloy systems. A crack susceptibility map covering 121 alloy compositions was constructed for each of the three ternary alloy systems at each of the following three levels of back diffusion: no back diffusion, back diffusion under a 100 °C/s cooling rate, and back diffusion under 20° C/s. The location of the region of high crack susceptibility, which is the most important part of the map, was shown in each of the nine calculated maps. These locations were compared with those observed in crack susceptibility tests by previous investigators. With back diffusion considered, either under 20 or 100 °C/s, the agreement between the calculated and observed maps was good especially for Al-Mg-Si and Al-Cu-Mg. Thus, the maximum | dT/d(f S ) 1/2 | can be used as a crack susceptibility index to construct crack susceptibility maps for ternary Al alloys and to evaluate the effect of back diffusion on their crack susceptibility. [ABSTRACT FROM AUTHOR]

Al-Mg alloys, despite their wide freezing temperature range ΔT f , can have good resistance to cracking during solidification. To help understand why, the mushy zone of 5086 Al (∼Al-4.0 Mg) was quenched during arc welding and the cooling curve measured to locate the beginning of the original mushy zone (liquidus temperature T L ) and the end (eutectic temperature T E ). Since little eutectic was visible just slightly behind the beginning of the quenched mushy zone, little liquid was here in the original mushy zone, i.e., solidification already ended well above T E . Since no dendrites were visible, either, and since the highest Mg content measured was well below the maximum solubility in solid Al, C SM (17.5 wt% Mg), microsegregation was very mild here in the original mushy zone. These results suggest significant Mg back diffusion occurred during solidification (because of very high C SM ), causing: 1. fraction solid f S to increase much faster with decreasing temperature T , 2. ΔT f to narrow down, and 3. dendritic grains to bond together extensively ( f S ≈ 1) to resist intergranular cracking earlier (well above T E ). Since | d(f S )/dT | increased, | dT/d(f S ) 1/2 | decreased to decrease the crack susceptibility index, i.e., the maximum | dT/d(f S ) 1/2 |. All these changes reduce the crack susceptibility. For comparison, 2014 Al (∼Al-4.4Cu) was also quenched during arc welding. At the end of the quenched 2014 Al mushy zone, continuous eutectic, dendrites and microsegregation were all very clear. Thus, solidification ended at T E and thin liquid films still separated grains at the end of the original mushy zone to allow intergranular cracking. Calculated T-(f S ) 1/2 curves showed the index is reduced significantly by back diffusion in Al-4.0 Mg (∼5086 Al) but not in Al-4.4Cu (∼2014 Al). [ABSTRACT FROM AUTHOR]

Cracking can occur during solidification in welding and casting. The present study attempted to deal with some fundamental questions regarding the susceptibility to cracking during solidification. How does the phase diagram affect the crack susceptibility? Can back diffusion occur in welding? How is the dihedral angle related to bridging between grains? To help answer the questions, the maximum | dT / d ( f S ) 1 / 2 | ( T is temperature and f S fraction solid) was calculated, whose validity as the crack susceptibility index was verified recently. To deal with curved solidus and liquidus lines (i.e., variable equilibrium segregation coefficient k ), f S was calculated as a function of T by numerical integration instead of by a simple analytical equation for constant k . Based on the secondary dendrite arm spacing λ 2 in common Al arc welds and the λ 2 − t f data of Al alloys ( t f is local solidification time), it was shown that back diffusion can occur in Al arc welding. Binary Al alloy systems were investigated over wide ranges of the eutectic temperature T E (229–548 °C) and k (about 0–0.87 at T E ). It was shown that with a very low T E the crack susceptibility can still be relatively low if k is very high at T E to increase the effect of back diffusion on crack susceptibility reduction, consistent with the lower crack susceptibility of Al-Mg and even Al-Zn than Al-Cu. With both a very low T E and a very low k at T E , however, the crack susceptibility can be very high, consistent with the severe crack susceptibility of Al-Sn. The effect of the curvature of the liquidus and solidus lines on the crack susceptibility was shown. A possible link between the dihedral angle and bridging between grains was also shown. [ABSTRACT FROM AUTHOR]

Cracking during solidification is a serious defect in welds and castings. A criterion for cracking that, unlike previous criteria/models, considers the grain boundary (where cracking occurs) was proposed recently. Based on this criterion, the maximum | dT / d ( f S ) 1/2 | ( T is temperature and f S fraction solid) of an alloy was proposed as an index for its crack susceptibility and the validity of the index was verified. The present study used the index to demonstrate the important effect of diffusion on the crack susceptibility and explained the surprisingly low crack susceptibility of Al–Mg alloys in welding. This was done by deriving closed-form equations to calculate the curves of crack susceptibility (the index) vs. solute content for binary Al–Si, Al–Cu and Al–Mg alloys. The curves were Λ-shaped, consistent with those observed in the crack susceptibility tests of binary alloy systems. It was shown that diffusion from liquid into Al-rich dendrites reduces the peak of the Λ-curve and shifts it to higher solute contents. The very high Mg solubility in solid Al, 17.5 wt% according to the Al–Mg phase diagram, makes Mg diffusion unusually significant, thus explaining the good weldability of Al–Mg alloys. The present study indicates the need to consider diffusion when comparing Λ-curves of different alloy systems, where the phase diagram can affect diffusion, or different tests of the same alloy system, where the cooling rate during welding or casting can affect diffusion. [ABSTRACT FROM AUTHOR]

A HfO 2 /Al 2 O 3 multilayer has been deposited by an atomic layer deposition (ALD) technique on a hydrogenated-diamond (H-diamond) epitaxial layer. Electrical properties of the ALD-HfO 2 /Al 2 O 3 /H-diamond metal-insulator-semiconductor (MIS) diode have been investigated to compare with those of the single ALD-Al 2 O 3 /H-diamond and ALD-HfO 2 /H-diamond MIS diodes. The leakage current density for the ALD-HfO 2 /Al 2 O 3 /H-diamond MIS diode is smaller than 3.8 × 10 − 8 A·cm − 2 with electric field ranging from − 1.6 to 1.0 MV·cm − 1 . The dielectric constant for the ALD-HfO 2 /Al 2 O 3 multilayer is larger than that for the single ALD-Al 2 O 3 . The fixed charge density in the ALD-HfO 2 /Al 2 O 3 /H-diamond structure is much lower than that in the single ALD-HfO 2 /H-diamond structure. The electrical properties of the ALD-HfO 2 /Al 2 O 3 /H-diamond MIS field effect transistor have also been investigated. The source–drain current and extrinsic transconductance maxima are − 42.1 mA·mm − 1 and 6.2 ± 0.1 mS·mm − 1 , respectively. The effective mobility for the H-diamond channel layer has been determined to be 38.2 ± 0.5 cm 2 ·V − 1 ·s − 1 . [ABSTRACT FROM AUTHOR]

As the mathematical model has been developed in part I, the simulation results of the transport phenomena and solidification cracking in laser spot bead-on-plate welding of AA6063-T6 aluminum alloy and the experimental validation are presented in this paper. Modeling results showed that the solute concentration in the solidified region continuously increases during the solidification process. As the temperature is lower than the coherent temperature (i.e., the temperature at which the coherent mushy zone is just formed), the strains accumulated in the coherent mushy zone increase with the increasing solid fraction. The amount of strain in the mushy zone is primarily determined by the life (i.e., time span) of the coherent mushy zone, which is determined by the solidification range and solidification time. The increased solidification range and consequently solidification time extend the life of the coherent mushy zone, which increases the amount of strain and thus increases the likelihood of solidification cracking. The modeling results are in agreement with the experimental results. Both the experimental and modeling results exhibited that solidification cracking is prone to occurring near the top surface and middle part of the weld bead and an increase of laser power leads to the higher cracking susceptibility. [ABSTRACT FROM AUTHOR]

In this study, a transient unified model including simulation of the temperature, velocity, solute (MgSi) concentration and stress fields, free surface, and laser-induced plasma, has been developed to predict the transport phenomena and solidification cracking susceptibility during laser spot bead-on-plate welding of aluminum alloy. The model consists of the modeling of heat, momentum and mass transports in the metal and plasma zones, thermomechanical modeling, and evaluation of solidification cracking. The full set of mathematical equations and numerical methods are presented. The main challenges and the corresponding solutions for the modeling are discussed. In this model, the lever-rule based on the phase diagram was used to deal with the macroscale segregation at the solid-liquid interface, while the solute transfer due to the diffusion and convection were calculated by the conservation equations for transport phenomena. The solute redistribution in the weldment is coupled with the changes of liquidus and solidus temperatures of the material. The total strain consists of the elastic, viscoplastic, and thermal parts that are coupled with the calculated temperature, velocity, and solute in the weldment. The criterion for the weld solidification cracking was established based on the strain theory, in which the cracking initiates only when the strain exceeds the threshold strain in the brittle temperature range (btr). [ABSTRACT FROM AUTHOR]

Ta2O5 films have been deposited on hydrogen-terminated diamond (H-diamond) by a radio-frequency sputter-deposition technique at room temperature. Electronic band structure of Ta2O5/H-diamond heterojunction has been investigated by X-ray photoelectron spectroscopy. Based on the binding energies of core-levels and valence band maximum values, valence band offset has been found to be 1.5±0.2eV for the Ta2O5/H-diamond heterointerface. It shows a type-II band configuration with conduction band offset of 2.4±0.2eV. The large ΔEV value makes the Ta2O5/H-diamond heterojunction probably suitable for the application of high power and high frequency field effect transistors. [ABSTRACT FROM AUTHOR]

In this work, experimental and numerical approaches are performed to explore the influence of scanning strategies on the microstructure, crystallographic texture as well as the mechanical behavior of Ti-6Al-4V alloy manufactured by Laser Powder Bed Fusion (LPBF). In-situ monitored data of the energy intensity show that different scanning strategies result in variations of energy intensity distribution. The characterization of the microstructure and crystallographic texture reveals that the sample with hexagon scan pattern displays the structure with columnar primary β phase, while the specimens with chessboard scan exhibit equiaxial-like morphology. EBSD and TEM results provide evidence of the appearance of residual β nanoparticles. A finite element model is developed to further explain the phase transformation during LPBF and the formation mechanism of residual β particles. The numerical results indicate that the appearance of the residual β phase is attributed to the preheating/reheating effect by the adjacent tracks and successive layers, and the final phase composition of the LPBF-built Ti-6Al-4V alloy combines the α′, α, and β phases. Findings in the present paper show that various scanning strategies lead to a clear diversification in the microstructure, crystallographic texture, and phase composition of LPBF-built samples, which opens a route towards the tailoring of mechanical properties and isotropic behaviors in additive manufacturing. [ABSTRACT FROM AUTHOR]

Abstract: To accurately evaluate the danger from rock bursts during coal mining, uniaxial compression tests of composed coal rock at different loading rates were carried out. The effect of the rate and path of loading and unloading on the mechanical properties of the composed coal rock has been analyzed. The overall elastic modulus, peak strength, and residual strength of the composed coal rock lie among that of roof, coal, and floor. The stress–strain characteristics of the composed coal rock depended on the part of the system with the smallest stiffness. The stress–strain curve during the post-peak failure stage was smoother than that of a single rock specimen on the whole. The stiffness difference markedly influenced the failure form and propensity to rockburst of the composed coal rock. With an increase of loading rate, the strain increment of the composed coal rock in the elastic phase, the plastic phase, and the failure phase gradually increased, and the strain at the peak point rose linearly. Faster strain rates made the curves smoother with smaller slopes. In comparison to monotonic loading, all the strain increments of the composed coal rock in the elastic phase, the plastic phase, and the peak strength point of cyclic loading were smaller; both the elastic modulus and peak strength were greater. Fast loading enhanced the capacity of the composed coal rock to convert outside energy to its own elastic energy. With an increase of loading rate, both the post-peak secant modulus and the strain softening modulus of the composed coal rock gradually decreased as negative logarithmic curves on the whole. The dynamic failure time gradually decreased as a hyperbolic curve, with enhanced brittleness. Consequently, composed coal rock and the rapid loading and unloading effect induced by mining should be considered for evaluating rockburst propensity. [Copyright &y& Elsevier]

Background: Estrogen receptor (ER) positive human epidermal growth factor receptor 2 (HER2) negative breast cancer (ER+/HER2−BC) and triple-negative breast cancer (TNBC) are two distinct breast cancer molecular subtypes, especially in tumor immune microenvironment (TIME). The TIME of TNBC is considered to be more inflammatory than that of ER+/HER2−BC. Natural killer (NK) cells are innate lymphocytes that play an important role of tumor eradication in TME. However, studies focusing on the different cell states of NK cells in breast cancer subtypes are still inadequate. Methods: In this study, single-cell mRNA sequencing (scRNA-seq) and bulk mRNA sequencing data from ER+/HER2−BC and TNBC were analyzed. Key regulator of NK cell suppression in ER+/HER2−BC, S100A9, was quantified by qPCR and ELISA in MCF-7, T47D, MDA-MB-468 and MDA-MB-231 cell lines. The prognosis predictability of S100A9 and NK activation markers was evaluated by Kaplan–Meier analyses using TCGA-BRAC data. The phenotype changes of NK cells in ER+/HER2−BC after overexpressing S100A9 in cancer cells were evaluated by the production levels of IFN-gamma, perforin and granzyme B and cytotoxicity assay. Results: By analyzing scRNA-seq data, we found that multiple genes involved in cellular stress response were upregulated in ER+/HER2−BC compared with TNBC. Moreover, TLR regulation pathway was significantly enriched using differentially expressed genes (DEGs) from comparing the transcriptome data of ER+/HER2−BC and TNBC cancer cells, and NK cell infiltration high/low groups. Among the DEGs, S100A9 was identified as a key regulator. Patients with higher expression levels of S100A9 and NK cell activation markers had better overall survival. Furthermore, we proved that overexpression of S100A9 in ER+/HER2-cells could improve cocultured NK cell function. Conclusion: In conclusion, the study we presented demonstrated that NK cells in ER+/HER2−BC were hypofunctional, and S100A9 was an important regulator of NK cell function in ER+BC. Our work contributes to elucidate the regulatory networks between cancer cells and NK cells and may provide theoretical basis for novel drug development. [ABSTRACT FROM AUTHOR]

• Frustum tube system enhances both conduction and convection. • Geometry modification significantly affects heat transfer in pure PCM. • Combination of frustum tube and metal foam further improves melting performance. • The frustum tube system outperforms the conical shell one. In this study, seven vertical shell-tube latent heat storage (LHS) systems are built to explore the effect of geometry on the melting and solidification behavior of phase change material (PCM). The performances of these systems using pure PCM (paraffin RT82) and composite PCM (paraffin RT82 embedded in copper foam) are investigated. Two-dimensional numerical model based on the enthalpy-porosity method and two-temperature energy equations is developed and verified with the experimental data. The solid-liquid interface, isotherms, time histories of liquid fraction and stored energy are used to evaluate the thermal performance. Results show that the conical shell system enhances natural convection compared with the cylinder system, whereas the frustum tube system enhances both convection and conduction. Geometry modification has little effect on the thermal performance of composite metal foam/PCM. Compared with the cylinder LHS system, the complete melting time with geometry modification is reduced by at least 9.2% for pure PCM, and less than 5.9% for composite metal foam/PCM. Moreover, it is also found that the frustum tube system outperforms the conical shell system in both melting and solidification, regardless of metal foam and HTF material. [ABSTRACT FROM AUTHOR]

A strong and hard hanging roof causes high underground stress in underground mines, leading to rock burst, coal and gas outburst, or large deformations in roadways. To address these problems, hydraulic fracturing can form hydraulic cracks in strong hanging roofs and promote fractures in the hanging-roof. However, it is difficult to ensure that hydraulic cracks propagate vertically through rock strata. Therefore, a novel method has been proposed that uses hydraulic fracturing to generate vertical fractures in hard hanging roofs for-roof cutting and stress relief. The method exploits the additional horizontal tensile stress produced by the bending deformation of the roof so that the fracturing point occurs in a desirable tensile-stress area, and therefore to promote the vertical expansion of hydraulic cracks that cut off the rock strata. In this paper, the position of the maximum additional horizontal tensile stress is taken to be the reasonable fracturing position given by a mechanical model. Solving this model indicates that a shorter hanging roof equates to a thicker hanging roof, a larger elastic modulus, a smaller elastic cushion coefficient, and a fracturing position that is deeper in the coal wall. The various factors that affect the reasonable fracturing position may be ordered in terms of their impact as follows: hanging-roof length > hanging-roof elastic modulus > hanging-roof thickness > elastic cushion coefficient > horizontal stress. The proposed method has been applied to roadway 5103 of the Majiliang Coal Mine of Datong Coal Mine Group Co., Ltd. The results show that hydraulic fracturing forms vertical hydraulic cracks at the point of maximum additional horizontal tensile stress, which can effectively control the deformation in the surrounding rock. The fracturing position calculated by using this model is reasonable and reliable and can be used to guide the on-site construction. [ABSTRACT FROM AUTHOR]

In this work, the tensile behavior and microhardness of 316L stainless steel fabricated by selective laser melting under different process parameters were investigated. The ultimate tensile strength decreased slightly with increasing energy input, while the opposite tendency was observed for the elongation to failure. Microstructure characterizations were performed to relate the pore morphology, melting pool geometry, solidification cell structure, and grain sizes to the mechanical performance of as-built samples. Fine grains with high fraction of low-angle grain boundaries and fine cellular structures with nano-inclusions are observed in the sample fabricated with a high scanning speed (1000 mm/s). As a result, the sample shows high ultimate tensile strength of up to 707 MPa, while maintaining a total elongation of 30%. The sample fabricated with a low scanning speed (800 mm/s) shows high ductility with total elongation to failure of 55%. The improved ductility is mainly attributed to the elimination of residual pores and melting pool boundaries, which result in brittle features in the as-built samples. The results indicate that selective laser melting may act as a physical metallurgy method to modify the microstructure, and thus improve the mechanical performance of metallic materials. Unlabelled Image • The scanning speed altered melting pool boundaries, residual pores, solidification cells, nano-inclusions and grain sizes. • High ultimate tensile strength was attributed to fine cellular structures and fine grains with low-angle grain boundaries. • Low scanning speed resulted in an enhanced ductility due to the minimization of residual defects and melting pool boundaries. [ABSTRACT FROM AUTHOR]

Rapid melting and solidification of powder particles through a high-power laser is the characteristic feature of selective laser melting (SLM), which controls the material and physical properties of fabricated components. Considering the multi-track multi-layer nature of an actual SLM process, an investigation of thermal behavior and melt pool morphology in multi-track multi-layer SLM of the 316L steel is presented in this paper. The SLM process of a four-layer component with multiple tracks was modeled. Element birth and death technique was used to simulate the layer built-up process. The established FEM model was used to investigate the variations in thermal variables and melt pool morphology with increasing number of layers. Moreover, the influence of various processing parameters in a multi-track multi-layer SLM was also studied. The results show that maximum melt pool temperature, melt pool width, and melt pool depth increase with increasing number of layers, whereas heating rates and cooling rates decrease with increasing number of layers. Compared with the previous layer, melt pool lifetime was observed to have a decreasing trend for layer 2 and increasing trend for layers 3 and 4. An increase in melt pool depth and decrease in melt pool width was observed by increasing hatch spacing. Furthermore, it was found that increasing laser power and scanning speeds both increase the heating and cooling rates. [ABSTRACT FROM AUTHOR]

Thanks to its excellent intrinsic properties, diamond is promising for applications of high-power electronic devices, ultraviolet detectors, biosensors, high-temperature tolerant gas sensors, etc. Here, an overview of high-k oxides on hydrogenated-diamond (H-diamond) for metal-oxide-semiconductor (MOS) capacitors and MOS field-effect transistors (MOSFETs) is demonstrated. Fabrication routines for the H-diamond MOS capacitors and MOSFETs, band configurations of oxide/H-diamond heterointerfaces, and electrical properties of the MOS and MOSFETs are summarized and discussed. High-k oxide insulators are deposited using atomic layer deposition (ALD) and sputtering deposition (SD) techniques. Electrical properties of the H-diamond MOS capacitors with high-k oxides of ALD-Al2O3, ALD-HfO2, ALD-HfO2/ALD-Al2O3 multilayer, SD-HfO2/ALD-HfO2 bilayer, SD-TiO2/ALD-Al2O3 bilayer, and ALD-TiO2/ALD-Al2O3 bilayer are discussed. Analyses for capacitance-voltage characteristics of them show that there are low fixed and trapped charge densities for the ALD-Al2O3/H-diamond and SD-HfO2/ALD-HfO2/H-diamond MOS capacitors. The k value of 27.2 for the ALD-TiO2/ALD-Al2O3 bilayer is larger than those of the other oxide insulators. Drain-source current versus voltage curves show distinct pitch-off and p-type channel characteristics for the ALD-Al2O3/H-diamond, SD-HfO2/ALD-HfO2/H-diamond, and ALD-TiO2/ALD-Al2O3/H-diamond MOSFETs. Understanding of fabrication routines and electrical properties for the high-k oxide/H-diamond MOS electronic devices is meaningful for the fabrication of high-performance H-diamond MOS capacitor and MOSFET gas sensors. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have sparked intense interest among the scientific community owing to their extraordinary mechanical, optical, electronic, and thermal properties. In particular, the outstanding electronic and optical properties of 2D materials make them show great application potential in high-performance photodetectors (PDs), which can be applied in many fields such as high-frequency communication, novel biomedical imaging, national security, and so on. Here, the recent research progress of PDs based on 2D materials including graphene, transition metal carbides, transition-metal dichalcogenides, black phosphorus, and hexagonal boron nitride is comprehensively and systematically reviewed. First, the primary detection mechanism of 2D material-based PDs is introduced. Second, the structure and optical properties of 2D materials, as well as their applications in PDs, are heavily discussed. Finally, the opportunities and challenges of 2D material-based PDs are summarized and prospected. This review will provide a reference for the further application of 2D crystal-based PDs. [ABSTRACT FROM AUTHOR]

A series of Y 2 Ti 2 O 7 glass-ceramic which is the main crystal phase is pyrochlore for actinide immobilization were synthesized by a new method combining oxide pre-crystallization and hot pressing. Y 2 Ti 2 O 7 was evenly distributed in the glass medium, increasing the temperature promoted the rapid growth of Y 2 Ti 2 O 7 grains, and increasing the pressure was conducive to maintaining the uniformity of Y 2 Ti 2 O 7 grains. Driven by a pressure, the glass component filled the gap well between the Y 2 Ti 2 O 7 grains, and the glass-ceramic obtained a compactness close to the theoretical density, so that it had an excellent microstructure and served the immobilization of actinide better. [ABSTRACT FROM AUTHOR]

During the operation of supercritical CO 2 (sCO 2 ) radial inflow turbines (RITs), sonic conditions may happen, which will decrease their efficiency. Non-standard design geometries are needed to reduce the losses. However, modifying the turbine geometry is a challenge, especially as the optimum shape may be non-intuitive; commercial computational fluid dynamics (CFD) software is not friendly towards automation by surrogate scripts, and the traditional design method for blade passage shape is not suited to the optimisation of aerodynamic turbine design. Hence, in this study, a stator nozzle for a 120 kW sCO 2 RIT, whose geometries are obtained from in-house preliminary design code TOPGEN t m , has been optimised with a modularised geometry optimiser. To parametrise the geometry, a parametrised stator mesh generator based on a meridional streamline is developed. Bulk CFD simulations are carried out with OpenFOAM ® , to form a Pareto front with a vector of 14 variables. Three final stators have been selected: they are the optimised Mach number distribution ( σ M ), the optimised outlet flow angle distribution ( σ α ) and a compromise case. The the outlet boundary properties of these stators are extracted and discussed. The optimised σ M case has the shortest divergent nozzle, returns the best σ M and the least loss; the optimised σ α case has the longest divergent nozzle and returns a better-uniformed outlet flow; the compromise case has the medium length of the divergent case. All these stators have fixed mass flow rates to allow de-coupling of the upstream system from the rotor. This study will ultimately benefit the development of the sCO 2 power cycle. [ABSTRACT FROM AUTHOR]

A laminated cubic solar absorber (LCSA) with double metal-dielectric layers is proposed. It plays an extremely crucial character in the utilization of solar energy. In particular, it is necessary to realize the efficient absorption and heat conversion of solar energy. Through numerical analysis and calculation, it is concluded that the absorption efficiency of LCSA is greater than 90% from 420 nm to 2112 nm. Moreover, the weighted average absorption of Air Mass 1.5 (AM1.5) in the solar radiation range (280 nm–2500 nm) is greater than 96.32%. To explore the mechanism of this absorber, we analyzed the electromagnetic field distribution of the four peaks, and concluded that the reason for achieving the wide-band absorption is that the depth of the double-layer metal dielectric cube produces surface plasmas with different wavelengths. The incident angle insensitivity and polarization independence of LCSA are realized. The simulation results indicate that the thermal radiation efficiency is more than 90% at 2000 K. Based on the above advantages and the high temperature resistance of tungsten (W) and aluminum oxide (Al 2 O 3), the proposed LCSA can be widely used in photothermal conversion and thermal emitters. We propose a laminated cubic solar absorber (LCSA) with double metal-dielectric layers. The results show that the absorption efficiency of LCSA is more than 90% at 420–2112 nm. In the solar radiation range (280 nm–2500 nm), the weighted average absorptivity is greater than 96.32%. And the thermal radiation efficiency at 2000 K is above 90%. Based on the excellent absorption properties and high temperature resistance of the materials, the proposed LCSA can be widely used in photothermal conversion and heat emitter. [Display omitted] • Our proposed solar absorber has a wide absorption range and an average absorption efficiency of more than 93% over the main solar radiation range (280 nm–3000 nm). • The solar absorber has high stability in solar thermal energy conversion. • The weighted average absorption rate at AM1.5 is more than 96% and the thermal radiation efficiency at 2000 K is more than 90%. • The absorber has polarization Angle independence and incident Angle insensitivity. [ABSTRACT FROM AUTHOR]

As a nonthermal microbial inactivation technology, pulsed electric field (PEF) treatment technology shows potentials in liquid food sterilization and other biological applications. The purpose of this study is to investigate the effect of PEF treatment on sterilization, the physical and the chemical properties of raw milk. Fresh raw milk samples were subject to PEF process with electric field strength ranged from 15 to 35 kV/cm for 1.25–5 ms in this study. The sterile rate and the shelf-life were evaluated and compared for PEF-treated, pasteurized, and untreated raw milk samples. It was demonstrated that similar inactivation effect was achieved as compared with pasteurization when raw milk was PEF-treated for 5 ms using 35-kV/cm field strength. The concentration of protein and free amino acids (FAA) was also measured and the results indicated that the PEF process promoted the protein-FAA transition as the concentration of FAA in the raw milk sample increased by as much as 14%. It is also shown that the input energy density of PEF treatment can be the deciding factor which affects both inactivation of microorganisms and the transformation of composition in the liquid food. [ABSTRACT FROM AUTHOR]

Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments. [ABSTRACT FROM AUTHOR]

Joining the advanced high-strength steels and conventional steels is a critical issue for the manufacturing of lightweight vehicles. Resistance element welding (REW) is an emerging joining method for dissimilar metals and alloys by applying an auxiliary rivet-like resistance element in resistance spot welding (RSW). In this study, an electrical-thermal-mechanical coupled REW model for high-strength dual-phase (DP) steel and Q235 steel was developed by considering contact resistances as functions of temperature and surface contacting area. The results show that the welding element in REW serves to concentrate the current flow and thus Joule heat generation at the faying interface between the element and workpiece. For welding DP600 and Q235 workpieces with a small thickness ratio (≤0.4) or a high electrical resistivity ratio (≥3), REW could effectively mitigate nugget shifting between workpieces and reducing the thermal excursion to the electrode compared to RSW. Adding well-designed insulation layers in REW could further concentrate the current within the welding element, and enables a large-sized nugget at a lower current. This study is significant because it provides a better understanding of the nugget development under the electrical-thermal-mechanical interaction at interfacial contacts in REW and contributes to its further advance. [ABSTRACT FROM AUTHOR]

Background: Psoriasis is a complex chronic inflammatory skin disease. The aim of this study was to analyze potential risk genes and molecular mechanisms associated with psoriasis. Methods: GSE54456, GSE114286, and GSE121212 were collected from gene expression omnibus (GEO) database. Differentially expressed genes (DEGs) between psoriasis and controls were screened respectively in three datasets and common DEGs were obtained. The biological role of common DEGs were identified by enrichment analysis. Hub genes were identified using protein–protein interaction (PPI) networks and their risk for psoriasis was evaluated through logistic regression analysis. Moreover, differentially methylated positions (DMPs) between psoriasis and controls were obtained in the GSE115797 dataset. Methylation markers were identified after comparison with the common genes. Results: A total of 118 common DEGs were identified, which were mainly involved in keratinocyte differentiation and IL-17 signaling pathway. Through PPI network, we identified top 10 degrees as hub genes. Among them, high expression of CXCL9 and SPRR1B may be risk factors for psoriasis. In addition, we selected 10 methylation-modified genes with the higher area under receiver operating characteristic curve (AUC) value as methylation markers. Nomogram showed that TGM6 and S100A9 may be associated with an increased risk of psoriasis. Conclusion: This suggests that immune and inflammatory responses are active in keratinocytes of psoriatic skin. CXCL9, SPRR1B, TGM6 and S100A9 may be potential targets for the diagnosis and treatment of psoriasis. [ABSTRACT FROM AUTHOR]

Background: This study was performed to understand the prevalence of and possible risk factors for cholecystolithiasis in Uyghur, Kazakh, Han, and other ethnic groups in the Xinjiang Uyghur autonomous region of China.Methods: Subjects were enrolled using typical case sampling and multistage stratified random sampling. We collected epidemiological data regarding cholecystolithiasis using a standard questionnaire of risk factors for gallbladder disease in Xinjiang. The subjects completed the questionnaire and underwent an abdominal ultrasound examination of the liver and gallbladder.Results: This study included 5454 Xinjiang residents aged ≥ 18 years. The prevalence of cholecystolithiasis was 15% (11.3% in men and 17.1% in women), and the sex difference was statistically significant (male-to-female odds ratio [OR] 1.867; p < 0.001). The cholecystolithiasis prevalence was also significantly different among the Han, Uyghur, Kazakh, and other ethnic groups (13.1%, 20.8%, 11.5%, and 16.8%, respectively; p < 0.001). The prevalence of cholecystolithiasis in northern Xinjiang was 13.5% and that in southern Xinjiang was 17.5%; this difference was also statistically significant (OR 1.599; p < 0.001). Across all ethnic groups, the cholecystolithiasis prevalence significantly increased with age (all p < 0.01) and body mass index (BMI) (all p < 0.01). A multivariate logistic regression analysis indicated that cholecystolithiasis prevalence was associated with sex, age, BMI, smoking, diabetes, fatty liver disease, and geographical differences between northern and southern Xinjiang.Conclusions: The prevalence of cholecystolithiasis was significantly higher in the Uyghur ethnic group than in the Han, Kazakh, and other ethnic groups; in women than in men; in southern Xinjiang than in northern Xinjiang; in patients with fatty liver disease; and increased with age and BMI. Our findings could provide a theoretical basis for the formulation of control measures for cholecystolithiasis. [ABSTRACT FROM AUTHOR]

Background: This study aimed to establish a traumatic hemorrhagic shock (THS) model in swine and examine pathophysiological characteristics in a dry-heat environment. Methods: Forty domestic Landrace piglets were randomly assigned to four study groups: normal temperature non-shock (NS), normal temperature THS (NTHS), desert dry-heat non-shock (DS), and desert dry-hot THS (DTHS) groups. The groups were exposed to either normal temperature (25°C) or dry heat (40.5°C) for 3 h. To induce THS, anesthetized piglets in the NTHS and DTHS groups were subjected to liver trauma and hypovolemic shock until death, and piglets in the NS and DS groups were euthanized at 11 h and 4 h, respectively. Body temperature, blood gas, cytokine production, and organ function were assessed before and after environmental exposure at 0 h and at every 30 min after shock to death. Hemodynamics was measured post exposure and post-shock at 0 h and at every 30 min after shock to death. Results: Survival, body temperature, oxygen delivery, oxygen consumption, and cardiac output were significantly different for traumatic hemorrhagic shock in the dry-heat groups compared to those in the normal temperature groups. Lactic acid and IL-6 had a marked increase at 0.5 h, followed by a progressive and rapid increase in the DTHS group. Conclusions: Our findings suggest that the combined action of a dry-heat environment and THS leads to higher oxygen metabolism, poorer hemodynamic stability, and earlier and more severe inflammatory response with higher mortality. [ABSTRACT FROM AUTHOR]

An Al2O3 thin film is assembled on an unin- tentionally doped ZnO for metal–insulator–semiconductor (MIS) capacitors. Leakage current density (J), capacitance–voltage (C - V) properties, and their thermal stabilities are investigated. The J -values for the MIS capacitors before and after annealing at 300 °C are lower than 2.0 × 10−7 A/cm2 at a gate voltage of −10.0 ~ 10.0V. Frequency-dependent C-V characteristic shows a stable maximum capacitance for the MIS capacitor before annealing. However, it decreases dramatically at 1 MHz for that after annealing at 300 C, which is attributed to the change of ZnO channel resistance. Flat band voltage shifts in the–curves after annealing at 300 C are one order lower than those before annealing, indicating the decrease of positive fixed charge density in the Al2O3 film. There are ledge phenomena for hysteresis characteristics in the curves, which result possibly from the delayed evacuation of minority carriers in deep depletion region. By considering the Fowler–Nordheim tunneling model, band configurations of the Al2O3/ZnO heterojunctions are clarified to be straddling gap structures with conduction band offsets larger than 1.3 eV. [ABSTRACT FROM AUTHOR]

Tool condition monitoring (TCM) is extremely important to ensure production efficiency and workpiece quality. It is crucial to extract and select suitable features from raw signals to improve the robustness and feasibility of TCM systems. This paper introduces a cutting force singularity analysis approach for TCM in milling, which correlates tool wear states with force waveform variations. The Holder exponents (HEs) were selected as the index of singularities. HEs are calculated by wavelet transform modulus maxima (WTMM). The raw signal is de-noised based on WTMM estimation, which can effectively preserve singularities compared with traditional filters. Fisher's discriminant ratio (FDR) is employed to rank the discriminant capability of statistical features of HEs. It is found that means of HEs and quantities of singular points estimated from feed forces Fx show the strongest class-discriminant ability. Then, these features were chosen as training samples to propose a TCM approach based on the support vector machine (SVM). Experimental results indicate that this approach provides reliable and effective advice for tool change. [ABSTRACT FROM AUTHOR]

Bio-n-butanol has attracted great attention as a potential alternative fuel in internal combustion engines (ICEs) due to its favorable physicochemical properties. However, the main issue impeding the use of bio-butanol in ICEs is its relatively high cost and energy consumption of dehydration and recovery processes in acetone-n-butanol-ethanol (ABE) or isopropanol-n-butanol-ethanol (IBE) fermentation technologies. Some researchers have proposed to use intermediate fermentation product, i.e. water-containing ABE or IBE, for clean combustion. Therefore, an experimental evaluation of spark-ignition (SI) engine fueled with water-containing IBE-gasoline blends was carried out in this study. Effects of IBE and water addition on combustion, performance, and emissions characteristics were first investigated at stoichiometric condition. Then, a “drop-in” fuel test was performed, i.e. IBE9W1 (9 vol.% IBE, 1 vol.% water and 90 vol.% gasoline) was compared with pure gasoline under various engine loads (3 and 5 bar BMEP) and equivalence ratios (Φ = 0.83–1.25). It was found that IBE9W1 showed a higher brake thermal efficiency, and a lower CO, NO x and BTX (benzene, toluene and xylene) emissions. The results indicate that water-containing IBE could be used as a fuel candidate in SI engine due to its eco-friendly production method and potential to improve energy efficiency and reduce emission pollutants. [ABSTRACT FROM AUTHOR]

During the fabrication of AlSi10Mg alloys by laser powder bed fusion (LPBF), the high-power density incident on the melt pool locally results in rapid heating and cooling rates, which leads to residual stress inevitably. Since the residual stress can lead to defects in the LPBF-built parts, it is necessary to reduce them by post-process treatments. However, the conventional heat treatments (HT) will weaken the mechanical properties while removing the residual stress, which is still one of the major challenges in additive manufacturing. This work proposes a deep cryogenic treatment (DCT) to reduce the residual stress, while maintaining the mechanical performance. The residual stress were measured by the hole-drilling strain-gauge method. The mechanical properties and microstructure were investigated using hardness measurements, tensile tests, scanning electron microscopy, and electron back-scattered diffraction. The results indicate that this treatment can relieve up to 72.7% of the residual stress, which is equivalent to the 76.5% reduction achieved by heat treatment. Moreover, this treatment can improve the tensile strength by 245 MPa and hardness by 56.72 HV 0.2 in comparison to the heat-treated samples. It is suggested that plastic deformation occurred at the interfaces between Al matrix and eutectic-Si networks due to the discordant volume shrinkage responsible for the stress relief. Thermal stress was evaluated to verify the occurrence of the plastic deformation. The present work proves that the proposed DCT is an effective method to simultaneously reduce the residual tensile stress and maintain the strength and elongation in the samples built by additive manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Charging effect frequently occurs when characterizing nonconductive materials using electrons as probes and/or signals and can impede the acquisition of useful information about the material under investigation. It is not adequate to investigate it merely by experiments, but theoretical investigations, for which the Monte Carlo method is a suitable tool, are also necessary. In this paper we review Monte Carlo simulations and selected experiments, intending to provide general insight into the charging effects induced by electron beam irradiation. We will introduce categories of the charging effect, the theoretical framework that is adopted in Monte Carlo modeling of the charging effect and present some typical simulation results. At last, with the knowledge on charging effect imparted by the above contents, we will discuss the measures that can be used for minimizing it. [ABSTRACT FROM AUTHOR]