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The quench sensitivity of the corrosion and mechanical properties of an Al-Zn-Mg-Cu-Cr-Zr alloy was investigated utilizing tensile testing, intergranular corrosion experiments and microstructure characterization. The research results indicated that, with a decrease in quenching rate, quenching precipitates sequentially nucleated non-uniformly at grain boundaries (GBs) (η phase), E phase (η phase) and Al3Zr particles (η and T phases). As the quenching rate decreased, the size and area fraction of quenching precipitates increased within the grains, consuming many solute atoms. This led to a reduction in the precipitation of the η′ strengthening phase during the aging process, resulting in a decrease in mechanical properties. Simultaneously, the decrease in quenching rate resulted in a significant increase in the size of the η phase at the GBs, Zn and Mg content, and the width of the precipitate-free zone at the GBs, making the GBs more susceptible to corrosion. This accelerated the rate of corrosion crack propagation along the GBs, reducing the corrosion resistance of the alloy. [ABSTRACT FROM AUTHOR]

Based on the quenching experiments, the precipitation behavior of 7085 aluminum alloy at different quenching rates was investigated through electrical conductivity testing, microstructure characterization, and thermodynamic calculations. The study reveals that as the quenching rate decreases, the electrical conductivity increases, and there is an increase in the types and nucleation sites of quenching precipitation phases. The preferred nucleation sites for precipitation are in the following order: high-angle grain boundaries (HAGBs), low-angle grain boundaries (LAGBs), non-coherent Al3Zr particles within recrystallized grains (RGs), dislocations, and coherent Al3Zr particles within subgrains (SGs). The precipitation sequence of quenching phases is as follows: η, T, and Y phases. With the decrease in quenching rate, the η phase is first observed to precipitate at HAGBs, followed by LAGBs, non-coherent Al3Zr particles within RGs, dislocations, and coherent Al3Zr particles within SGs. Furthermore, at quenching rates below 152 °C/min, the T phase is observed to precipitate at LAGBs. At a quenching rate of 129 °C/min, the Y phase is observed to precipitate at dislocations. [ABSTRACT FROM AUTHOR]

HVE-400 ion implanter is special ion implantation equipment for semiconductor materials boron and phosphorus doping. The ion source and extraction deflection system are at high voltage platform, while the corresponding control system is at ground voltage position. The control signals and measurement signals of various parameters at the high-voltage end need to be transmitted between ground voltage and high voltage through optical fibers to isolate high voltage. Upgrading is carried out due to the aging of the optical fiber transmission control and monitoring system, which cannot work stably. The transformation replaces the original distributed single-point control method with an advanced distributed centralized control method, and integrates all control and monitoring functions into an industrial control computer for digital operation and display. In the computer software, two kinds of automatic calculation of ion mass number are designed. After upgrading, the implanter high-voltage platform control and monitoring system features digitalization, centralized control, high reliability, strong anti-interference, fast communication speed, and easy operation. [ABSTRACT FROM AUTHOR]

The [1,2]- and [2,3]-Stevens rearrangements are one of the most fascinating chemical bond reorganization strategies in organic chemistry, and they have been demonstrated in a wide range of applications, representing a fundamental reaction tactic for the synthesis of nitrogen compounds in chemical community. However, their applicabilities are limited by the scarcity of efficient, general, and straightforward methods for generating ammonium ylides. Herein, we report a general difluorocarbene-induced tertiary amine-involved [1,2]- and [2,3]-Stevens rearrangements stemmed from in situ generated difluoromethyl ammonium ylides, which allows for the rearrangements of versatile tertiary amines bearing either allyl, benzyl, or propargyl groups, resulting in the corresponding products in one reaction under the same reaction conditions with a general way. Broad substrate scope, simple operation, mild reaction conditions and late-stage modification of natural products highlight the advantages of this strategy, meanwhile, this general rearrangement reaction is believed to bring opportunities for the transformations of nitrogen ylides and the assembly of valuable tertiary amines and amino acids. This will further enrich the reaction repertoire of difluorocarbene species, facilitate the development of reactions involving difluoromethyl ammonium salts, and provide an avenue for the development of this type of rearrangement reactions.The Stevens rearrangements are a fundamental and powerful tool in the synthetic organic chemistry repertoire, but these transformations are known to be limited in their tolerance for some common functional groups. Here, the authors present a methodology that uses a difluorocarbene unit to induce a Stevens rearrangement, which enables smooth inclusion of allylic and propargyl moieties in the transformation. [ABSTRACT FROM AUTHOR]

This study investigates the influence of hot rolling on the quench sensitivity and heterogeneous precipitation behavior of 7150 aluminum alloy using an end-quenching process combined with conductivity testing, hardness testing, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, scanning transmission electron microscopy, and high-resolution transmission electron microscopy. The results reveal that hot rolling significantly increases the quenching sensitivity of the 7150 aluminum alloy, as evidenced by the enhancement in conductivity difference from 0.7 to 1.6% IACS and the rise in hardness drop from 5.5 to 12% at both ends after hot rolling. Microstructural analysis indicates the presence of equiaxed grains with low dislocation density and well-coherent Al3Zr particles in the primitive alloy, with small precipitates of the η phase on the Al3Zr particles. Subsequent to hot rolling, recrystallization occurs, thereby resulting in the generation of numerous high-angle grain boundaries (HAGBs), incoherent Al3Zr particles, dislocations, and coherent Al3Zr particles. Consequently, this leads to increased variety, nucleation sites, sizes, and quantities of heterogeneous precipitates. HAGBs, characterized by high interfacial energy, are found to be the most favorable for the nonuniform nucleation and precipitation of the η phase, followed by low-angle grain boundaries. Significant precipitation of the η and T phases is observed on the noncoherent Al3Zr dispersoids within the recrystallized grains and some subgrains (SGs). Furthermore, the high-dislocation-density SGs not only facilitate the precipitation of the η and T phases but also result in the precipitation of the S and Y phases. [ABSTRACT FROM AUTHOR]

Experiment was carried out to investigate the influence of quench rate on the axial compression property of AA6060 two-chamber extrusion profile by comparing the compressed-air quench and water quench. It reveals that the higher quench rate is required for the axial compression in contrast to the axial tension. And the crack sensitivity during the compression deformation has no single correlation to the tensile properties. The optical microscopy and transmission electron microscopy studies were conducted to correlate the microstructure and fracture characteristics. It indicates that the primary cracks are both present in the valley of tensile surface and inside the tensile area. The primary cracks on the surface are because of the strain localization, and the intermetallic particles (AlFeSi) initiated the micro-cracks inside the tensile area. Intergranular primary crack is favored when AlFeSi particles, grain boundary misorientation and intense slip band work together. The comparison of two quench conditions shows low quench rate results in high rate grain precipitates and high sensitivity to crack during the compression and bend. It attributes to cohesive bonds weakening between the grains when a large amount of precipitates occur on the grain boundary. Intergranular ductile fracture mechanism is unlikely present in water quench materials because of the low matrix strength combined with the weak population of grain boundary particles. [ABSTRACT FROM AUTHOR]

Electrochemical conversion of CO2 to formic acid using Bismuth catalysts is one the most promising pathways for industrialization. However, it is still difficult to achieve high formic acid production at wide voltage intervals and industrial current densities because the Bi catalysts are often poisoned by oxygenated species. Herein, we report a Bi3S2 nanowire-ascorbic acid hybrid catalyst that simultaneously improves formic acid selectivity, activity, and stability at high applied voltages. Specifically, a more than 95% faraday efficiency was achieved for the formate formation over a wide potential range above 1.0 V and at ampere-level current densities. The observed excellent catalytic performance was attributable to a unique reconstruction mechanism to form more defective sites while the ascorbic acid layer further stabilized the defective sites by trapping the poisoning hydroxyl groups. When used in an all-solid-state reactor system, the newly developed catalyst achieved efficient production of pure formic acid over 120 hours at 50 mA cm–2 (200 mA cell current). Achieving high pure formic acid production from CO2 electroconversion is of high interest yet challenging. Here the authors report vitamin C functionalized Bi3S2 nanowire catalyst to achieve selective, active, and stable formic acid production. [ABSTRACT FROM AUTHOR]

Zn alloys have attracted considerable attention owing to their favorable biocompatibility, mechanical strength, and corrosion resistance. Such outstanding biodegradable metallic materials may also have potential practical applications in biomedicine. By means of microstructure characterization, immersion corrosion tests, and electrochemical measurement, this study researched into the effect of homogenization treatment on the microstructure and in vitro degradation behavior of a novel biodegradable Zn-Mg-Sr alloy. The experimental results indicated serious dendritic segregation in the as-cast Zn-Mg-Sr alloy. The metallic phases in the as-cast Zn-Mg-Sr alloy were non-equilibrium MgZn2, Sr-rich SrZn13, and equilibrium Mg2Zn11. By raising the homogenization temperature or lengthening soaking time, the non-equilibrium MgZn2 and SrZn13 gradually dissolved into the Zn matrix, and the dendritic segregation was mostly eliminated. Compared with as-cast Zn-Mg-Sr alloys, homogenized alloys exhibited a slower degradation rate and better pitting corrosion resistance. Based on the experimental results and homogenization kinetic analysis, the optimum homogenizing parameters for the biodegradable Zn-Mg-Sr alloy were 350 °C and 24 h, so the corresponding degradation rate was 0.083 mm/year. [ABSTRACT FROM AUTHOR]

Aqueous zinc (Zn)-ion batteries (AZIBs) are one of the most promising large-scale energy storage devices because of the excellent features of zinc metal anodes, including high theoretical capacity (5,855 mAh·cm−3 and 820 mAh·g−1), high safety, and natural abundance. Nevertheless, the large-scale applications of AZIBs are mainly limited by the severe interfacial side reactions of zinc metal anodes, which results in low plating/stripping Coulombic efficiency and poor cycling stability. To address this issue, we report an artificial Ta2O5 protective layer on zinc foil (Ta2O5@Zn) for suppressing side reactions during Zn deposition/stripping. The results of density functional theory calculation and experiments indicate that Ta2O5@Zn anode can inhibit the side reactions between the electrolyte and zinc anode through the isolation effect. Benefiting from this advantage, the symmetric cells with Ta2O5@Zn anode delivered an ultralong lifespan of 3,000 h with a low overpotential at 0.25 mA·cm−2 for 0.05 mAh·cm−2. Furthermore, the full cells consisting of Ta2O5@Zn anode and MnO2 or NH4V4O10 cathode all present outstanding electrochemical performance, indicating its high reliability in practical applications. This strategy brings new opportunities for the future development of rechargeable AZIBs. [ABSTRACT FROM AUTHOR]

Highlights: The electrochemical techniques utilizing metal-organic frameworks (MOFs)-based catalysts for converting CO2 into chemical species are discussed. The structure–activity relationship of MOF-based catalysts in electrocatalytic CO2 reduction reactions is thoroughly reviewed The challenges and opportunities of large-scale applications of MOF-based materials in electrochemical CO2 reduction reactions are discussed, and possible directions for the future development of MOFs and their derivatives are outlined. Electrochemically reducing CO2 to more reduced chemical species is a promising way that not only enables the conversion of intermittent energy resources to stable fuels, but also helps to build a closed-loop anthropogenic carbon cycle. Among various electrocatalysts for electrochemical CO2 reduction, multifunctional metal–organic frameworks (MOFs) have been employed as highly efficient and selective heterogeneous electrocatalysts due to their ultrahigh porosity and topologically diverse structures. Up to now, great progress has been achieved in the design and synthesis of highly active and selective MOF-related catalysts for electrochemical CO2 reduction reaction (CO2RR), and their corresponding reaction mechanisms have been thoroughly studied. In this review, we summarize the recent progress of applying MOFs and their derivatives in CO2RR, with a focus on the design strategies for electrocatalysts and electrolyzers. We first discussed the reaction mechanisms for different CO2RR products and introduced the commonly applied electrolyzer configurations in the current CO2RR system. Then, an overview of several categories of products (CO, HCOOH, CH4, CH3OH, and multi-carbon chemicals) generated from MOFs or their derivatives via CO2RR was discussed. Finally, we offer some insights and perspectives for the future development of MOFs and their derivatives in electrochemical CO2 reduction. We aim to provide new insights into this field and further guide future research for large-scale applications. [ABSTRACT FROM AUTHOR]

Doping with different valence ions in Aurivillius compounds can induce lattice distortion and further affect the ferroelectric and magnetic properties of the materials. In this work, CaxBi6–xFe0.5Co0.5Ti4O18 thin films were prepared to study the influence of the substitution of Ca2+ for Bi3+ on the microstructure and the dielectric, ferroelectric, leakage, and magnetic properties. The results show that the lattice distortion and the internal stress are both increased with increasing Ca2+ doping level. The dielectric and ferroelectric measurements suggest that the film with a low doping concentration (x = 0.2) exhibits better performance than the films with higher doping concentrations. Although lattice distortion and valence changes in the ions have been produced, which may have affected the distortion of the A/B-O octahedral crystal structure, tests of magnetic properties demonstrate that no regular changes are caused by the Ca2+ doping. [ABSTRACT FROM AUTHOR]

We consider a natural mechanical system on a Finsler manifold and study its curvature using the intrinsic Jacobi equations (called Jacobi curves) along the extremals of the least action of the system. The curvature for such a system is expressed in terms of the Riemann curvature and the Chern curvature (involving the gradient of the potential) of the Finsler manifold and the Hessian of the potential w.r.t. a Riemannian metric induced from the Finsler metric. As an application, we give sufficient conditions for the Hamiltonian flows of the least action to be hyperbolic and show new examples of Anosov flows. [ABSTRACT FROM AUTHOR]

Developing ultrasensitive and user-friendly methods for the detection glucose has attracted more and more attention. By virtue of high selectivity and sensitivity, enzyme-based glucose sensor plays a key role in point-of-care sensing technology for detecting glucose concentration. In this study, Amplex Red (AR), as both indicator and mediator, was investigated to detect glucose in presence of glucose oxidase (GOx) enzymes using colorimetric and electrochemical methods. Without using any advanced techniques and sophisticated nanomaterials, 1 μM glucose can be easily detected through simply detecting the solution color with a visual colorimetric method. On the other hand, the electrochemical method can provide much higher sensitivity for the detection of glucose, which achieves a linear range spanning from 20 nM to 3.56 μM with a limit of 7.3 nM (signal-to-noise ratio SNR = 3). It is also found that the presence of other sugars such as fructose, lactose, and maltose have very limited interference effects on the detection of glucose. More importantly, a bare GC electrode was used in all these electrochemical measurements without any electrode surface modification, guaranteeing a simple and fast operation. The analytical platforms for the detection of glucose presented here not only provide simple, fast, and ultrasensitive methods, but also have the potential to advance the sensing technology in the application of other health diagnostic research areas. [ABSTRACT FROM AUTHOR]

The Aurivillius compound PbxBi6−xFe0.5Co0.5Ti4O18 thin films were prepared via chemical solution deposition method and the influence of Pb2+ ions doping on the structure, ferroelectric and leakage properties were studied. With the increasing concentration of Pb2+ ions, the lattice distortion is increased and the growth of the films along ab plane is promoted. The calculation results show that the internal stress of the films increases with the increase of Pb2+ concentration. For the samples with low Pb2+ doping concentration (x < 0.6), the leakage current densities are also decreased, which can be attributed to the decrease in oxygen vacancy concentration. Due to the enhanced lattice distortion and decreased leakage current densities, the ferroelectric properties are improved. The film with x = 0.2 has a high saturation polarization of 42.3 µC/cm2. According to the fitting results, the leakage conduction mechanism is attributed to the combined effect of space-charge-limited conduction mechanism and ionic conduction mechanisms. [ABSTRACT FROM AUTHOR]

Electrochemical nitrogen reduction reaction (NRR) is considered as an alternative to the industrial Haber-Bosch process for NH3 production due to both low energy consumption and environment friendliness. However, the major problem of electrochemical NRR is the unsatisfied efficiency and selectivity of electrocatalyst. As one group of the cheapest and most abundant transition metals, iron-group (Fe, Co, Ni and Cu) electrocatalysts show promising potential on cost and performance advantages as ideal substitute for traditional noble-metal catalysts. In this minireview, we summarize recent advances of iron-group-based materials (including their oxides, hydroxides, nitrides, sulfides and phosphides, etc.) as non-noble metal electrocatalysts towards ambient N2-to-NH3 conversion in aqueous media. Strategies to boost NRR performances and perspectives for future developments are discussed to provide guidance for the field of NRR studies. [ABSTRACT FROM AUTHOR]

We use the general additive–multiplicative hazard model to analyze the length biased data with right censorship and use the estimating equation method that incorporates the information about length-biased sampling scheme to do the inference. In addition, some graphical and numerical methods are developed for assessing the adequacy of the general additive–multiplicative hazard model. The procedures are derived from cumulative sums of martingale-based residuals over follow-up time and covariate values. The simulations are conducted to insure the good performance of this method. An application to the Oscar data is also illustrated. [ABSTRACT FROM AUTHOR]

For the first time in an application to nuclear astrophysics, a process induced by the unstable 5 He = ( 4 He-n) nucleus, the 3 He+ 5 He → 2 α reaction, has been studied through the Trojan Horse Method (THM). For that purpose, the quasi-free (QF) contribution of the 9 Be( 3 He, α α ) 4 He reaction was selected at E 3 He = 4 MeV incident energy. The reaction was studied in a kinematically complete experiment following a recent publication (Spitaleri et al. in Eur Phys J A 56:18, 2020), where for the quasi free contribution the momentum distribution between α and 5 He particle cluster in the 9 Be nucleus in the ground state have been extracted. The angular distribution of the QF 3 He+ 5 He → 2 α reaction was measured at θ cm = 78 ∘ –115 ∘ . The energy dependence of the differential cross section of the 3 He+ 5 He → 2 α virtual reaction was extracted in the energy range E cm = 0–650 keV. The total cross section obtained from the Trojan-horse method was normalized to absolute cross sections from a theoretical calculation in the energy range E cm =300–620 keV. [ABSTRACT FROM AUTHOR]

Nanobeams are widely used in nano-electro-mechanical systems and biotechnology as actuators, transistors, resonators and sensors. In the present paper, we propose a theory to analyze the large deformation of nanobeams with surface effect by the core–shell model and surface-energy-based model. Adopting Euler–Bernoulli beam model and the principle of minimum potential energy, the nonlinear governing equation as well as the boundary conditions is deducted incorporated surface effects and geometric nonlinear deformation. As an example, the postbuckling of nano-cantilever is studied using our theory. The results agree well with the theoretical analysis of surface effects with surface stress. This study helps to understand the influence of the surface effects on the mechanical behavior of nanodevices and also will help in accurately measuring and manufacturing nanodevices and systems based nanowires. [ABSTRACT FROM AUTHOR]

Highlights: Recent advances of a hot-casting technique used to deposit high-quality perovskite films are reviewed. Perovskite films with large grain size, uniform thickness, and preferred crystalline orientation are deposited. Future perspectives on the upscaling of perovskite solar cell are described.Organic–inorganic metal halide perovskite solar cells (PSCs) have recently been considered as one of the most competitive contenders to commercial silicon solar cells in the photovoltaic field. The deposition process of a perovskite film is one of the most critical factors affecting the quality of the film formation and the photovoltaic performance. A hot-casting technique has been widely implemented to deposit high-quality perovskite films with large grain size, uniform thickness, and preferred crystalline orientation. In this review, we first review the classical nucleation and crystal growth theory and discuss those factors affecting the hot-casted perovskite film formation. Meanwhile, the effects of the deposition parameters such as temperature, thermal annealing, precursor chemistry, and atmosphere on the preparation of high-quality perovskite films and high-efficiency PSC devices are comprehensively discussed. The excellent stability of hot-casted perovskite films and integration with scalable deposition technology are conducive to the commercialization of PSCs. Finally, some open questions and future perspectives on the maturity of this technology toward the upscaling deposition of perovskite film for related optoelectronic devices are presented. [ABSTRACT FROM AUTHOR]

A new study of the quasi-free contribution to the 3 He + 9 Be → 3 α reaction (Q value = 19.004 MeV) at low E 3 He energy is presented. The reaction was studied in a kinematically complete experiment at beam energy of 4 MeV. To clarify the presence of the quasi-free mechanism, the 4 He – 5 He momentum distribution of the 9 Be ground state was extracted. Standard tests were also carried out to confirm the presence of the quasi-free contribution and are reported in this work. The full width at half maximum of the 4 He – 5 He inter-cluster momentum distribution inside 9 Be was measured with improved accuracy, by adopting several different approaches that all led to consistent results. These preliminary investigations on the reaction mechanism are fundamental for future studies employing the Trojan Horse Method, with the 5 He unbound nucleus as a virtual projectile. [ABSTRACT FROM AUTHOR]

Mg–Al alloys were inoculated by MgO powder. The effects of MgO addition amount, holding time after MgO addition and Al content on the grain refining efficiency were systematically investigated in the present study. The refining mechanism was discussed. MgO cannot serve as the effective substrate of primary α-Mg phase. Significant grain refinement of Mg–Al alloys with the Al content over than 2% could be obtained. Al is an indispensable element to ensure the grain refining efficiency of MgO addition on Mg alloys. The optimum MgO powder addition amount and the holding time were about 1.5% and 10 min, respectively. MgO could react with Al in Mg melt, resulting in the formation of MgAl2O4 particles. As the comparative experiments, the grain refinement on the pure Mg and Mg–3%Al alloy inoculated by MgAl2O4 powder was proven. Based on theoretical calculation and experimental results, the grain refinement of Mg–Al alloy inoculated by MgO powder is attributed to the newly formed MgAl2O4 particles, which could act as the effective heterogeneous nuclei of primary α-Mg phase. [ABSTRACT FROM AUTHOR]

Zn1 − xMnxO (x = 0.002–0.01) nanoparticles were synthesized by co-precipitation method. The detailed crystal structure and compositional characterizations were characterized by the XRD patterns, Raman spectra, XPS, HRTEM and SEM. the XRD and XPS results show the Mn2+ ions are substitute for Zn2+ ions in the ZnO matrix. In the Raman spectra, the E2(high) peak shifts to lower frequency and the higher intensity of A1(LO) peak appears in the sample with increasing doping concentrations of Mn, indicating a higher concentration of donor defects are introduced in ZnO nanoparticles. Then, the carrier concentration induced by oxygen vacancies are analyzed from the optical absorption spectra. By analyzing the O1s XPS spectrum by Lorentz fitting and PL spectra by Gaussian fitting, the oxygen vacancy concentration increases with Mn doping concentration. The present results suggest that the doped Mn2+ ions play a significant role on enhancing the carrier concentration of ZnO materials. [ABSTRACT FROM AUTHOR]

Objective: To investigate the value of 'swallow-tail' sign and putaminal hypointensity on 3 T susceptibility-weighted imaging (SWI) for distinguishing multiple system atrophy (MSA) from idiopathic Parkinson's disease (IPD).Methods: Three groups - 39 MSA patients, 18 IPD patients,and 31 healthy controls (HCs) - were administered a 3 T SWI sequence to evaluate 'swallow-tail' sign and putaminal hypointensity using visual scales from 0 to 2 and 0 to 3 scores, respectively. The diagnostic accuracy of the two signs separately and combined was calculated using a receiver operating characteristic curve, with clinical diagnosis as the gold standard.Results: The scores of 'swallow-tail' sign were lower in IPD than in MSA or in HCs, as well as for putaminal hypointensity in IPD or HCs than in MSA (p < 0.05). The sensitivity and specificity of 'swallow-tail' sign and putaminal hypointensity were 87.9% and 83.3%, and 35.9% and 100%, respectively, in the respective patient groups. The area under the curve of combined signs was increased from 0.85 ('swallow tail') or 0.68 (putaminal hypointensity) to 0.93.Conclusion: The combination of 'swallow-tail' sign and putaminal hypointensity can increase the accuracy of discriminating between MSA and IPD.Key Points: • Differential diagnosis of MSA and IPD is still challenging in clinical practice. • Absence of 'swallow-tail' sign is a valuable biomarker for IPD on SWI. • Putaminal hypointensity is a valuable biomarker for MSA on SWI. • Combined 'swallow- tail' sign and putaminal hypointensity increase diagnostic accuracy. [ABSTRACT FROM AUTHOR]

BaTiO-CoFe O composite thin films with different thicknesses were fabricated via chemical solution deposition. Magnetic annealing and non-field annealing processes were applied in the sintering process, respectively. Variations of the structure and magnetic properties of the composite films induced by the magnetic annealing were investigated. It is found that the mean grain size and grain boundary are increased and decreased, respectively. For the magnetic-annealed films, the internal strain is reduced with the increase of film thickness. Magnetic measurements show that the M is also increased with the film thickness and the magnetic-annealed films have bigger M values than the non-field-annealed films. Based on the experimental results, it can be concluded that the effect of magnetic annealing on the structure and properties of the composite films is decreased with the increase of film thickness. [ABSTRACT FROM AUTHOR]

Using the available pressure-volume-temperature equation of state of sodium chloride, we show that the self-diffusion coefficients of sodium and chloride in sodium chloride as a function of temperature and pressure can be successfully reproduced in terms of bulk elastic and expansivity data. We use a thermodynamic model that interconnects point-defect parameters with bulk properties. Our calculated diffusion coefficients and point-defect parameters, including activation enthalpy, activation entropy, and activation volume, well agree with reported experimental results when uncertainties are considered. Furthermore, the ionic conductivity of sodium chloride inferred from our predicted diffusivities of sodium through the Nernst-Einstein equation is compared with previous experimental data. [ABSTRACT FROM AUTHOR]

The influence of hydrogenated annealing temperature on the room temperature ferromagnetism of Mn-doped ZnO films was investigated. The X-ray diffraction and X-ray photoelectron spectra reveal Mn ions have been incorporated into wurtzite ZnO lattices. The saturation magnetization increases quickly with the increasing N/H-annealing temperature (T) until the temperature reaches 750 °C, and then the saturation magnetization approaches a constant value. Some foamlike materials appear in the non-continuous films when the T is 640 °C or above, and saturation magnetization of these films become stronger than that of the (600-630 °C) annealed films. The results of X-ray photoelectron spectra, SEM images and photoluminescence spectrum suggest that oxygen vacancy concentration of the annealed films increases with increasing T, which leads to the ferromagnetism of the Mn-doped ZnO film. These results demonstrate that oxygen vacancies, especially singly ionized oxygen vacancies, play a crucial role in mediating ferromagnetism of the Mn-doped ZnO film. [ABSTRACT FROM AUTHOR]

The precipitation behavior in an Al-6.8Zn-1.9Mg-1.0Cu-0.12Zr alloy after direct quenching from solution heat treatment temperature of 470 °C to 205-355 °C was investigated by means of hardness tests, electrical conductivity tests, and transmission electron microscopy. At temperatures below 265 °C, the hardness increased gradually to a peak value and then decreased rapidly with time. At 265 °C, the hardness was almost unchanged within the initial 2000 s and then decreased gradually. At higher temperatures, the hardness decreased slowly with time. The electrical conductivity started to increase after a certain period of time and then tended to maintain a constant value at all temperatures. Microstructure examination indicated heterogeneous precipitation of the η phase at grain boundaries and inside grains during holding at 205 °C and 325 °C. Based on the electrical conductivity data, the precipitation kinetics could be described quite well by the Johnson-Mehl-Avrami-Komolgorov relationship with a n value varying between 0.78 and 1.33. The activation energy was estimated to be about 44.9 kJ/mol, which is close to that expected for a dislocation diffusion mechanism. Time-temperature-transformation diagrams were constructed and the nose temperature ranged from 295 °C to 325 °C. [ABSTRACT FROM AUTHOR]

Based on the classic augmented Lagrangian multiplier method, we propose, analyze and test an algorithm for solving a class of equality-constrained non-smooth optimization problems (chiefly but not necessarily convex programs) with a particular structure. The algorithm effectively combines an alternating direction technique with a nonmonotone line search to minimize the augmented Lagrangian function at each iteration. We establish convergence for this algorithm, and apply it to solving problems in image reconstruction with total variation regularization. We present numerical results showing that the resulting solver, called TVAL3, is competitive with, and often outperforms, other state-of-the-art solvers in the field. [ABSTRACT FROM AUTHOR]

The curvature and the reduced curvature are basic differential invariants of the pair (Hamiltonian system, Lagrangian distribution) on a symplectic manifold. We consider the Hamiltonian flows of the curve of least action of natural mechanical systems in sub-Riemannian structures with symmetries. We give sufficient conditions for the reduced flows (after reduction of the first integrals induced from the symmetries) to be hyperbolic in terms of the reduced curvature and show new examples of Anosov flows. [ABSTRACT FROM AUTHOR]

Based on the rock creep experiment, the data of aftershock sequence and post-earthquake deformation are used to estimate the viscosity of crust medium near earthquake focus. Firstly 9 samples that belong to 3 kinds of rock are conducted in creep experiment under constant pressure to obtain the creep curves directly. Inversion results show that the standard linear model is the best one to present the earth medium. It exhibits obvious elasticity within a short time, while it exhibits obvious rheology within a long time. The relationship between element module μ2 and the whole module μ of standard linear model or the module of real earth medium is calculated and analyzed. On the basis of μ2 = 25 μ, the sequence of aftershock of Gonghe earthquake in Qinghai Province is analyzed and the relationship between accumulated released strain and the time is obtained, which, combined with the creep experiment results, is used to estimate the viscosity of crustal medium in this area. The measured vertical deformation after the same earthquake also is combined with the creep experiment results, then it is used to calculate the relaxation time and viscosity through three different methods respectively, i.e. inversion of Kelvin model, difference method of deformation and viscoelastic dislocation theory. The viscosity of crustal medium in 32 km depth of earthquake focus of Gonghe area deduced from the different data and methods is about 1019 Pa·s, which is the same as the research results by other authors at home and abroad. [ABSTRACT FROM AUTHOR]

In this study, the room temperature thermal conductivities and microstructures of Al-Si binary alloys in as-cast, low-temperature annealing state and solid solution state are investigated. The experimental results show that annealing treatment increases the thermal conductivities of these alloys because of the decreasing Si concentration in α-Al matrix, which is determined by EPMA. The effect of solution treatment on the thermal conductivity of Al-xSi (0 ≤ x ≤ 12) alloys can be divided into two stages. When the Si content is less than 3 wt%, the thermal conductivities of solution treated specimens are lower than that of as-cast, which is mainly attributed to the increase in Si concentration. However, solution treatment improves the thermal conductivities of Al-xSi (x > 3) alloys owing to the spheroidization of Si phase. Quantitative study is conducted on the effect of Si element on thermal conductivity of as-cast Al-xSi alloys. The thermal conductivities of Al-xSi alloys are fitted using modified Series and Maxwell models based on the Si concentration in α-Al matrix, distribution and volume fractions of Si phases. The modified structural models provide a better fit to the measured thermal conductivity data. [ABSTRACT FROM AUTHOR]

The large-area silicon photodiode PIN is one of the candidates for the lead tungstenate photon detector readout in the large heavy ion collision experiment ALICE. The PIN-diode was assembled with the lead tungstate crystal and a low-noise preamplifier into a complete detector unit. A beam test of a 5 × 5 detector unit matrix was carried out on the SPS accelerator at CERN. The energy resolution was measured with the electron beam energy ranging from 5 to 40 GeV. The summation correction method was implemented, and an excellent linearity of the signal peak value of the detector versus the nominal beam energy was obtained. In addition, a preliminary study of the punch-through effect in the high energy range was performed. A bulge of high-energy signals was identified at beam energies above 10 GeV, but only accounting for less than 1% of the accumulated statistics. Considering the mean energy of the excess is twice large than the regular signal, it was probably mainly due to the accumulation caused by two electrons hitting the detector at the same time, rather than the punch-through effect. [ABSTRACT FROM AUTHOR]

Rolling resistance is a main consideration in quasi-static shear test simulations of particles via the discrete element method. However, not all rolling resistance models can satisfy the required objectivity and rate independence. A suitable model for spherical particles has been selected from five models in our previous works. In the current study, this model is combined with four normal and tangential contact models to confirm its applicability. After confirmation, the model is generalized to simulate direct shear tests on non-spherical particles. The stress-strain and dilatancy curves are rate-independent, and the relative rolling velocity between particles is objective. Furthermore, objectivity and rate independence for arbitrarily shaped particles are unchanged when normal stresses, volume fractions, or normal and tangential contact models are changed. Simulation results are also consistent with other experiment findings. For comparison, results are calculated for two other rolling resistance models; the shear curve at a single speed is consistent with the experiment, which has three stages: elastoplastic increasing, yielding, and keeping. However, the stress-strain curves at different shear rates do not coincide, which means that the models conflict with the rate independence of quasi-static granular systems. The virtues and defects of the five rolling resistance models are discussed from the perspectives of objectivity and rate independence. These two properties provide criteria for determining the appropriateness of a model, which has been rarely discussed in former studies. [ABSTRACT FROM AUTHOR]

Great attention has been focused on the design of good thermal conductivity and high-strength Al–Si alloys to ensure the dissipation of heat and load of electronic components. In this study, the Al–7Si alloy was modified by various content additions of Sr, B, RE and Sb elements. The results show that these modifiers can significantly improve the thermal conductivity and electrical conductivity of Al–7Si alloys to varying degrees. Among them, the 0.05 wt% Sr-modified Al–7Si alloy achieves the highest thermal conductivity (169.6 W/m K) and electrical conductivity (24.27 MS/m). The higher conductivity is due to the systematic optimization of eutectic Si. Sr-modified Al–7Si alloy can change the size, distribution of the eutectic Si phase and transform them from coarse plate-shaped to a fine short slab-shaped or coral-shaped. By these means, it will increase the number and mean free paths of heat transfer electrons, thereby improving the thermal conductivity of Al–7Si alloy. [ABSTRACT FROM AUTHOR]