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Although anisotropic phononic crystals (PnCs) could be utilized to control the phonon dispersions and thermal transports, rapidly discovering their properties presents a significant challenge due to the enormous consumption of traditional computational methods. In this study, we have developed machine learning techniques to forecast the thermal conductance of anisotropic PnCs (GPnC and GPnC/Gmem) based on the elastic constants, taking conventional inorganic and halide perovskites as examples for their thermoelectric applications. Our findings suggest that predicting GPnC/Gmem is more challenging than predicting GPnC attribute to the complex influence factors and spatial distribution patterns of the former. The GPnC and GPnC/Gmem of the weakest thermal anisotropic materials—all hexagonals are invariants in the (0 0 1) plane, because the velocities in this plane are direction-independent. The GPnC and GPnC/Gmem of the strongest thermal anisotropic material FAPbI3 reaches the minimum and maximum values in [1 1 0] and [1 0 0] directions, respectively. Ultimately, our machine learning models can map the hidden complex nonlinear relationships between target thermal properties and mechanical features to provide valuable insight for accurate and efficient prediction and analysis of the thermal behaviors of PnCs at a mesoscopic level under low temperatures. [ABSTRACT FROM AUTHOR]

Mn2+ doping effectively realizes white light emission in three-dimensional lead halide perovskite nanocrystals. Meanwhile, research on Mn-doped two-dimensional layered perovskite single crystal is limited. We report centimeter-scale Mn-doped PEA2PbBr4 (C6H5CH2CH2NH3+ and PEA+) single crystals prepared by a slow evaporation method. Mn2+ dopants mainly act as substitutional doping and exhibit paramagnetic properties in the crystal at low doping density, while interstitial doping of Mn2+ prevails and induces antiferromagnetic characteristics at high doping density. Mn:PEA2PbBr4 single crystals exhibit dual-band chromacity-tunable blue-orange photoluminescence originating from excitons and Mn2+ emission. The negative temperature quenching effect is achieved by Mn-doping defects for the temperature-dependent exciton photoluminescence. Upon testing in the low-pressure vacuum chamber, the Mn2+ peak of the single crystal shows a dramatic shift from 610 to 690 nm. These results indicate that Mn:PEA2PbBr4 single crystal can serve as a potential and promising luminescent device material that achieves color tunable properties by regulating the systematic changes in the intensity ratio of exciton emission and Mn2+ emission, which will be very helpful for exploring the application of perovskite in magneto-optical devices in the future. [ABSTRACT FROM AUTHOR]

In order to detect and identify fire accidents accurately and efficiently, an intelligent fire identification system based on neural network algorithm is designed, which can overcome the shortcomings of single information, complex wiring, poor adaptability, etc. The characteristic extraction of sensors is adopted in the information layer to solve the problems in multi-sensor fusion. The fire data are transmitted to the main controller through LoRa wireless module and fused by back propagation neural network, which is self-learning and adaptive. The output of neural network and fuzzy inference with other factors are used for decision criteria to improve the identification accuracy. The common combustibles and various interference sources are selected for fire tests. The result shows that the detection accuracy is up to 100% and the false alarm rate is lower than 0.1%, meanwhile, the system has the advantages of fast response and high detection efficiency. [ABSTRACT FROM AUTHOR]

A proposed ultra-high slew rate current recycling folded cascode operational transconductance amplifier (OTA) working in the subthreshold region is presented. By employing adaptive biasing and the proposed positive-feedback nonlinear current mirror techniques, it not only forces the charge or discharge path to enter the strong inversion region during slewing, but also provides an ultra-high output current, leading to a significant boost in the slew rate. The simulation results of the two OTAs designed in SMIC 0.18 μ m CMOS process demonstrate that the slew rate of our proposed OTA is enhanced 387 times than that of the conventional counterpart with the same power. [ABSTRACT FROM AUTHOR]

Dietary supplementation is prevalent in our daily life, in which tablet form plays an important role due to its long-term stability and cost-effectiveness. In the pharmaceutical industry, coordination polymer-based tablets are widely produced for dietary supplementation. The mechanical properties of such dietary supplements are very crucial for the tableting process and need to be broadly studied. In this study, the mechanical properties of a copper supplement, namely copper glycinate hydrate (Cu[O2CCH2NH2]2·H2O), have been studied via high-pressure synchrotron powder X-ray diffraction and density functional theory calculations. This material is a 1D coordination polymer, and adjacent chains are linked via hydrogen bonding in the structure. The measured bulk modulus (Ko) is ∼13.9 GPa, which is comparable to that of small organic drug crystals and far smaller than that of inorganic dietary supplements. The calculated Young's moduli (13.55–35.75 GPa) indicate a significant elastic anisotropy, and the directional dependent Young's modulus can be substantiated with the underlying atomic structure. Our experimental and calculated results provide useful quantitative information for tableting and formulating this dietary supplement in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

An adaptively biased low-dropout regulator (AB-LDO) with current mirror buffer has been proposed in previous literatures, which only solves a few of the specific problems of AB-LDO without additional synthetical analysis of the various performances. Based on the analysis, it is found that enhancing the current efficiency of operational transconductance amplifier (OTA) is a key factor to improve the performances of AB-LDO. A current reusing current-mode OTA (CRCM-OTA) with high current efficiency is proposed to apply to AB-LDO. Compared with the traditional AB-LDO, it can achieve an obvious improvement of AB-LDO performances including the current efficiency of AB-LDO, loop gain, and loop bandwidth without increasing the area and power consumption. This article also adopts an intuitive method different from the previous works to analyze the whole loop. The AB-LDO using an advanced CRCM-OTA was fabricated in SMIC 0.18 μm CMOS process, which has a transient undershoot of 26.25 mV with an output capacitor of 1 μF for a load step of 0–50 mA with edge time of 10 ns and realizes a performance figure of merit (FoM) value of 13.65 ps. [ABSTRACT FROM AUTHOR]

Force sensor becomes more and more miniature in order to achieve precise measurement in small place. A magnetostrictive micro sensor was proposed in the paper; meanwhile, the signal acquisition system was designed by Android platform and Arduino MCU to meet the popular mobile terminal. The structure of sensor and the hardware and software of system were designed to realize the functions of force signal acquisition, processing and analysis, and upload the data to mobile terminal in real time. It can be seen from the experimental tests: Firstly, the volume of sensor was less than 2 cm3 and had good linearity, while the sensitivity was 0.1537 mV/N and the repeatability error was 1.07%. Secondly, the system could effectively enlarge the output value of sensor more than 100 times and the nonlinear error was less than 1.5%, while the linearity and sensitivity can be kept well. This sensor with acquisition system had the advantages of easy realization, low cost, strong expansibility and simple operation, and it can be widely used in industrial control, mechanical automation, intelligent robot, and so on. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

All-inorganic cesium lead triiodide (CsPbI3) perovskite has been widely researched due to its outstanding photovoltaic properties. At room temperature, there are two orthorhombic CsPbI3 phases (black γ-CsPbI3 perovskite and yellow δ-CsPbI3 non-perovskite). In this study, these two polymorphic structures have been studied via density functional theory calculations in respect to their electronic and elastic properties. Our calculation results give full mapping of Young's moduli of the γ-CsPbI3 structure for all crystallographic orientations, which reveal that the optimum directions for stabilizing the γ-CsPbI3via strain are approximately along 〈012〉. Moreover, we found that these two polymorphs have distinct stiffness along respective octahedral chains due to their different kinds of octahedral connections. Furthermore, the calculated band structures and density of states disclose that both phases have direct bandgaps, and the bandgap of δ-CsPbI3 is much wider due to its weak Pb 6p–I 5p antibonding coupling in the conduction band and low octahedral connectivity. Our findings provide fundamental elastic and electronic insights which are instructive for strain engineering of photovoltaic γ-CsPbI3. [ABSTRACT FROM AUTHOR]

Methyl iodide (CH3I) was electrochemically degraded by using copper sheet as cathode and graphite sheet as anode in a two-compartment cell. The effects of key parameters on the degradation of CH3I, including tetraalkylammonium salts, current density, initial pH, and electrolyte concentration, were investigated. The results showed that 89% of CH3I can be removed under the optimized conditions of 0.05% tetrabutylammonium chloride (TBAC), current density of 3 mA cm−2, reaction temperature of 20 °C, initial pH of 4.5, and electrolyte of 0.5 M Na2SO4. Cyclic voltammetry was applied to investigate and preliminarily elucidate the electrochemical degradation mechanism. The major pathway for CH3I degradation is reductive deiodination. Dissociative electron transfer to CH3I led to carbon–iodine bond reductive cleavage, and the reactive hydrogen atom produced during electrolysis could promote the reductive process. CH4 and I− were the main products. This study suggests that electrochemical reduction may be a promising option for treatment of radioactive CH3I from nuclear power plants. [ABSTRACT FROM AUTHOR]

High pressure behavior of a 2D hybrid perovskite semiconductor, (BA)2PbBr4 (BA = benzylammonium), has been systematically studied via synchrotron powder X-ray diffraction over the range of 0-14.22 GPa. (BA)2PbBr4 shows a soft nature with a bulk modulus of 10(1) GPa and anisotropic linear compressibility with βa = 25(6), βb = 5.3(4), and βc = 15.1(8) TPa−1. Experiment-aided density functional theory calculations reveal that the structural changes of (BA)2PbBr4 under compression are attributed to the configurational alterations of BA+ organic cations and synergistic distortion of the (PbBr4)2− inorganic layer. Further extensive theoretical calculations of elastic tensors give full mapping of Young's moduli, shear moduli, and Poisson's ratios of (BA)2PbBr4, which confirm its anisotropic nature in elasticity. In addition, the photoluminescence of (BA)2PbBr4 exhibits a significant red-shift and an intensity decrease in response to hydrostatic stress which respectively arise from the contractions of Pb–Br bonds and distortions of PbBr6 octahedra in the inorganic layer mediated by the configurational alterations of BA+ cations upon compression. [ABSTRACT FROM AUTHOR]

The effect of chemistry on low energy recoil events was investigated at 10 K for each type of atom in pyrochlores, using molecular dynamics simulation. Contour plots of the threshold displacement energy ( E d) in Gd2Zr2O7 have been produced along more than 80 directions for each individual species. The E d surface for each type of atom in Gd2Zr2O7 is highly anisotropic; E d of Zr exhibits the largest degree of anisotropy, while that of O8 b exhibits the smallest. The recommended values of E d in Gd2Zr2O7 based on the observed minima are 56, 94 and 25 eV, respectively, for Gd, Zr, and O. The influence of cation radius on E d in pyrochlores A2B2O7 (with A-site ranging from Lu3+ to La3+ and B-site ranging from Ti4+ to Ce4+) was also investigated along three directions [100], [110], and [111]. The E d in pyrochlores strongly depended on the atom type, atom mass, knock-on direction, and lattice position. The defects produced after low energy displacement events included cation antisite defects, cation Frenkel pairs, anion Frenkel pairs, various vacancies, and interstitials. Ce doping in pyrochlores may affect the radiation response, because it resulted in drastic changes in cation and anion displacement energies and formation of an unusual type of anti-site defect. This work demonstrates links between E d and amorphization resistance. [ABSTRACT FROM AUTHOR]

Background and aims: Drought is predicted to have a profound impact on soil respiration. This study aimed to assess the effects of long-term precipitation decrease on soil respiration in a tropical rainforest. Methods: A precipitation reduction experiment was conducted in a tropical forest in southwest China at the beginning of 2011. Soil respiration and environmental parameters were measured monthly for three years. Results: The continuous precipitation reduction treatment did not affect the seasonal patterns of soil respiration, but it significantly increased soil respiration in the study plot during the rainy season, and the relationship between soil respiration and soil moisture differed in the control and reduction treatment in the rainy season. Compared with the net ecosystem exchange of carbon in this system, the increment of annual soil carbon emissions in the reduction treatment was considerable and should not be ignored. Conclusions: Our results indicate that the responses of soil respiration to precipitation decrease may vary seasonally and the variation of volumetric water content in different seasons may be an important factor leading to the seasonal variation. The variation of soil moisture among different ecosystems as well as in different seasons should be taken into consideration when predicting the future response of soil respiration to drought globally. [ABSTRACT FROM AUTHOR]

Anomalous mechanical materials, with counterintuitive stress-strain responding behaviors, have emerged as novel type of functional materials with highly enhanced performances. Here we demonstrate that the materials with coexisting negative, zero and positive linear compressibilities can squeeze three-dimensional volume compressibility into one dimension, and provide a general and effective way to precisely stabilize the transmission processes under high pressure. We propose a "corrugated-graphite-like" structural model and discover lithium metaborate (LiBO2) to be the first material with such a mechanical behavior. The capability to keep the flux density stability under pressure in LiBO2 is at least two orders higher than that in conventional materials. Our study opens a way to the design and search of ultrastable transmission materials under extreme conditions. Anomalous mechanical behaviors provide an opportunity to regulate the functions of materials. Here the authors show that materials with coexisting negative, zero and positive compressibilities can "squeeze" volume compressibility into one direction, and thus stabilize transmission processes under pressure. [ABSTRACT FROM AUTHOR]