ChemTS: An Efficient Python Library for de novo Molecular Generation

Automatic design of organic materials requires black-box optimization in a vast chemical space. In conventional molecular design algorithms, a molecule is built as a combination of predetermined fragments. Recently, deep neural network models such as variational auto encoders (VAEs) and recurrent neural networks (RNNs) are shown to be effective in de novo design of molecules without any predetermined fragments. This paper presents a novel python library ChemTS that explores the chemical space by combining Monte Carlo tree search (MCTS) and an RNN. In a benchmarking problem of optimizing the octanol-water partition coefficient and synthesizability, our algorithm showed superior efficiency in finding high-scoring molecules. ChemTS is available at https://github.com/tsudalab/ChemTS

Threshold current of field-free perpendicular magnetization switching using anomalous spin-orbit torque

Spin-orbit torque (SOT) is a candidate technique in next generation magnetic random-access memory (MRAM). Recently, experiments show that some material with low-symmetric crystalline or magnetic structures can generate anomalous SOT that has an out-of-plane component, which is crucial in switching perpendicular magnetization of adjacent ferromagnetic (FM) layer in the field-free condition. In this work, we analytically derive the threshold current of field-free perpendicular magnetization switching using the anomalous SOT. And we numerically calculate the track of the magnetic moment in a FM free layer when an applied current is smaller and greater than the threshold current. After that, we study the applied current dependence of the switching time and the switching energy consumption, which shows the minimum energy consumption decreases as out-of-plane torque proportion increases. Then we study the dependences of the threshold current on anisotropy strength, out-of-plane torque proportion, FM free layer thickness and Gilbert damping constant, and the threshold current shows negative correlation with the out-of-plane torque proportion and positive correlation with the other three parameters. Finally, we demonstrate that when the applied current is smaller than the threshold current, although it cannot switch the magnetization of FM free layer, it can still equivalently add an effective exchange bias field H_{bias} on the FM free layer. The H_{bias} is proportional to the applied current J_{SOT}, which facilitates the determination of the anomalous SOT efficiency. This work helps us to design new spintronic devices that favor field-free switching perpendicular magnetization using the anomalous SOT, and provides a way to adjust the exchange bias field, which is helpful in controlling FM layer magnetization depinning

Radio-sensitizing effect of ethyl caffeate on nasopharyngeal carcinoma CNE-2 cell line

Purpose: To investigate the radio-sensitizing effect of ethyl caffeate (ETF) on naso-pharyngeal carcinoma.Methods: MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay was used to evaluate the cell viability of CNE-2 cells, while their levels of caspase-3 and caspase-9 were determined by enzyme-linked immunosorbent assay (ELISA). In addition, a xenograft model was established in nude mice. The model was treated with ETF (40 mg/kg) and subjected to β-irradiation (10 Gy) for 28 days, during which tumor volume was determined at 4-day intervals. Expressions of caspase-3, caspase-9 and Bcl-2 were determined by western blotting assay.Results: β-irradiation (10 Gy) did not produce any obvious inhibitory effect on the proliferation of CNE-2 cells. However, ETF (10, 20 and 40 μg/mL) significantly enhanced the radiosensitivity of the cells to β- irradiation (p < 0.01) and significantly increased their levels of caspase-3 and caspase-9 (p < 0.01). The combination of ETF (40 mg/kg) with β-irradiation resulted in significant inhibition of tumor growth in mice xenograft model (p < 0.01). The combined treatment also resulted in significant up-regulation of expressions of caspase-3 and casepase-9 and significant down-regulation of Bcl-2 in the tumor tissues when compared with corresponding tissues from the control mice (p < 0.01).Conclusion: ETF significantly enhances the sensitivity of naso-pharyngeal carcinoma CNE-2 cells to β- irradiation, probably through induction of mitochondria-mediated apoptosis. ETF may be useful for treating naso-pharyngeal carcinoma in combination with radiation therapy.Keywords: Ethyl caffeate, Radio-sensitizing effects, Caspase, Nasopharyngeal carcinoma, CNE-2 cell line, β-irradiatio

Spin transport and dynamic properties of two-dimensional spin-momentum locked states

Materials with spin-momentum locked surface or interface states provide an interesting playground for studying physics and application of charge-spin current conversion. To characterize their non-equilibrium magnetic and transport properties in the presence of a time-dependent external magnetic field and a spin injection from a contact, we introduce three macroscopic variables: a vectorial helical magnetization, a scaler helical magnetization, and the conventional magnetization. We derive a set of closed dynamic equations for these variables by using the spinor Boltzmann approach with the collision terms consistent with the symmetry of spin-momentum locked states. By solving the dynamic equations, we predict several intriguing magnetic and transport phenomena which are experimentally accessible, including magnetic resonant response to an AC applied magnetic field, charge-spin conversion, and spin current induced by the dynamics of helical magnetization

Effect of Songyu Anshen Fang on expression of hypothalamic GABA and GABA(B) receptor proteins in insomniac rats induced by para-chlorophenylalanine

Purpose: To investigate the effects of the Chinese compound, Songyu Anshen Fang (SYF) on levels of GABA and GABA(B) receptor proteins in insomniac rats induced by para-chlorophenylalanine (PCPA).Methods: All rats were randomly separated into either a control group, insomnia group, or a SYF group (at a dose of 8.5 g/kg or 17 g/kg body weight per day). The rat model of insomnia was induced by intraperitoneal injection of PCPA, and SYF was administered intragastrically in suspension. All experimental groups were treated with a corresponding agent for one week. The levels of glutamic acid (Glu) and γ-aminobutyric acid (GABA) were determined by high performance liquid chromatography (HPLC); mRNA and protein expressions, and GABA(B) receptor levels were detected by real-time polymerase chain reaction (RT-PCR) and western blot.Results: SYF treatment with 8.5 or 17 g/kg/day decreased the levels of Glu and Glu/GABA ratios in the hypothalamus following abnormal increase by PCPA. Moreover, GABA(B) receptor, mRNA and protein expression decreased by PCPA in hypothalamus were significantly normalized by SYF.Conclusion: The study indicates that the effects of PCPA-induced insomnia can be alleviated by SYF modulation of neurotransmitter levels and the expression of GABA(B) receptor in the hypothalamus. This suggests that clinical application of SYF to treat insomnia may be feasible.Keywords: Songyu Anshen Fang, Para-chlorophenylalanine (PCPA), γ-Aminobutyric acid (GABA), GABA(B) receptor, Insomni

Research on the type and occurrence mechanism and prevention of coal pillar rockbursts

Coal pillar rockburst is a typical type of rockburst occurring in coal mining in China in recent years. How to summarize the engineering scale damage characteristics of coal pillar rockburst, reveal the mechanism of rockburst instability and formulate scientific and accurate anti-burst measures has become a difficult problem for coal mine science and technology personnel. The engineering characteristics and burst manifestation characteristics of three types of typical coal pillar burst accidents in China's coal mines are analyzed using field investigation, theoretical analysis and field monitoring, and the current coal pillar type burst in China is classified into three types: ground pressure superimposed type, cut creep type and overall destabilization type. The mechanical models of the occurrence mechanism of the three types of coal pillar burst are established respectively, the evaluation methods and prevention countermeasures of the three types of coal pillar burst hazards are proposed, and the occurrence mechanism of the three types of coal pillar burst is revealed. The mechanism of superimposed ground pressure type is that the superimposed stress applied to the coal pillar exceeds the critical value of the coal mass for burst instability, and the coal pillar is destabilized by minor or unconditional perturbation; the mechanism of overall instability burst is that the load borne by the coal body in the elastic bearing zone of the coal pillar exceeds its ultimate bearing capacity, and the coal body in the elastic bearing zone triggers the burst and causes the coal body in the shallow part of the coal pillar to fail extensively. The mechanism of cut creep rock burst is that the load transfers to the elastic bearing area due to the slow decrease of supporting capacity of coal pillar under long-term high stress, and when the load of the coal body in the elastic bearing area exceeds the critical value of burst, a large-scale coal body impact destabilization will occur. Due to the complex mining conditions in China, there are many hidden types of coal pillar bursts encountered during field production, therefore, in the prevention and control of bursts, it is necessary to strengthen the identification and prevention of these hidden coal pillar burst risks

Crystal growth, structure and thermal properties of noncentrosymmetric single crystals PrCa4O(BO3)3+

Noncentrosymmetric praseodymium calcium oxyborate single crystals, PrCa4O(BO3)3 (PrCOB), were grown by the Czochralski technique. The monoclinic unit cell parameters were found to be a = 8.177 Å, b = 16.157 Å, c = 3.629 Å and Z = 2 with space group Cm. Crystal density was measured using the Archimedes method, being on the order of 3.47 g cm-3. Thermal properties of PrCOB were investigated, where the specific heat was found to be 0.63 J g-1 °C-1 at room temperature, increasing to 0.85 J g-1°C-1 at 700°C. The thermal expansion coefficients were measured to be α11 = 7.99, α22 = 4.90 and α33 = 9.46 (10-6/°C), respectively. In addition, thermal diffusivity λ22 and thermal conductivity κ22 as a function of temperature were studied, where λ22 was observed to decrease from 0.89 to 0.58 mm2 s-1, while κ22 was found to maintain the same value, being ∼1.90 W m-1°C-1 over the temperature range of 20-700°C. 2013 The Royal Society of Chemistry

A Flexible Sensor and MIMU-Based Multisensor Wearable System for Human Motion Analysis

Motivation: Magnetic–inertial measurement units (MIMUs) and flexible sensors are widely used in the wearable measurement system for human motion monitoring, clinical gait detection, and robotics motion control. However, MIMUs demonstrate measurement error due to magnetic disturbance in the indoor environment, and flexible sensors usually have low performance on linearity and accuracy. Objective: This article is intended to eliminate the low-accuracy problem caused by magnetic disturbances and improve the measurement accuracy of MIMU–flexible-sensor-based wearable systems. Approach: 1) a three-stage real-time adaptive anti-disturbance data fusion (RT-ADF) algorithm is proposed, which contains an anti-disturbance filter based on a double Mahony filter along with a state observer, a signal holder for sensors’ data transmit synchronously, and a data fusion based on an adaptive Kalman filter; 2) the proposed algorithm is used and validated its performance on a designed MIMU–flexible sensor wearable system; and 3) ten groups of knee motions (flexion/extension), ten groups of hip motions (adduction/abduction), and ten groups of elbow motions (flexion/extension) have been done by seven subjects in the experiments. Main Results: The designed multisensor wearable system based on the presented data fusion algorithm demonstrates a high-accuracy performance under the magnetic disturbance environment, and the maximum root mean square error (RMSE) of the measured continuous 3-D motion angle of the knee, hip, and elbow cross all the experiments was 1.23°, 1.15°, and 3.67° for each axis.<br/