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As an important component carrying the core function and service life of switching appliances, the selection and improvement of electrical contact materials is of great significance. AgSnO2, which is non-toxic, environmentally friendly and has excellent performance, has become the most promising contact material to replace AgCdO. However, it has deficiencies in machinability and electrical conductivity. The property of AgSnO2 contact material was improved by doping element Cr. The relationship between the mechanical and electrical properties of AgSnO2 contact materials and doping concentrations were investigated and analyzed by simulation and experiment. Based on the first principle, the elastic constants of supercell models Sn1−xCrxO2 (x = 0, 0.083, 0.125, 0.167, 0.25) were calculated. The results show that the material with a doping ratio of 25% is least prone to warp and crack, and the material with a doping ratio of 12.5% has the best toughness and ductility and the lowest hardness, which leads to molding and is subsequently easier to process. The Cr-doped AgSnO2 contacts with different doping proportions were prepared by the sol–gel and powder metallurgy method. Additionally, their physical performance and electrical contact properties were measured in experiments. The results show that the doped SnO2 powders prepared by the sol–gel method realize integration doping, which is consistent with the crystal model constructed in the simulation calculation. Sn0.875Cr0.125O2 has lower hardness, which is beneficial to process and form. Doping helps to stabilize the arc root, inhibit the ablation of contact by arc, reduces arc duration and arc energy, improves the resistance to arc erosion of AgSnO2 contact material, and makes electrical contact performance more stable. The contact material with a doping concentration of 16.7% has the best arc erosion resistance. [ABSTRACT FROM AUTHOR]

Vacuum flat panel detectors (VFPDs) using cold cathode have important applications in large-area photoelectric detection. Based on the electron-bombardment-induced photoconductivity (EBIPC) mechanism, the photoconductor-type VFPDs achieved high detection sensitivity. However, pixelated imaging devices have not yet been developed. In this paper, we fabricate a 4 × 7 pixel vacuum flat panel detector array made of ZnS photoconductor and ZnO nanowires cold cathode for an imaging application. The responsivity of the device and the pixel current uniformity are studied, and imaging of the patterned objects is achieved. Our results verify the feasibility of VFPDs for imaging. [ABSTRACT FROM AUTHOR]

Skin cutaneous melanoma (SKCM) attracts attention worldwide for its extremely high malignancy. A novel term cytolytic activity (CYT) has been introduced as a potential immunotherapy biomarker associated with counter-regulatory immune responses and enhanced prognosis in tumors. In this study, we extracted all datasets of SKCM patients, namely, RNA sequencing data and clinical information from The Cancer Genome Atlas (TCGA) database and the Gene Expression Omnibus (GEO) database, conducted differential expression analysis to yield 864 differentially expressed genes (DEGs) characteristic of CYT and used non-negative matrix factorization (NMF) method to classify molecular subtypes of SKCM patients. Among all genes, 14 hub genes closely related to prognosis for SKCM were finally screen out. Based on these genes, we constructed a 14-gene prognostic risk model and its robustness and strong predictive performance were further validated. Subsequently, the underlying mechanisms in tumor pathogenesis and prognosis have been defined from a number of perspectives, namely, tumor mutation burden (TMB), copy number variation (CNV), tumor microenvironment (TME), infiltrating immune cells, gene set enrichment analysis (GSEA) and immune checkpoint inhibitors (ICIs). Furthermore, combined with GTEx database and HPA database, the expression of genes in the model was verified at the transcriptional level and protein level, and the relative importance of genes in the model was described by random forest algorithm. In addition, the model was used to predict the difference in sensitivity of SKCM patients to chemotherapy and immunotherapy. Finally, a nomogram was constructed to better aid clinical diagnosis. [ABSTRACT FROM AUTHOR]

Purpose: A high‐precision rotated elliptical beam profiling method based on pixel ion chamber is proposed in this paper. This method aims to improve the accuracy by modeling the transverse profile of rotated beam as an ellipse with additional correlation coefficient and eliminating the fitting error due to the volume averaging effect of pixel ion chamber. Methods: In pencil beam scanning (PBS) proton therapy systems, the transverse beam profile model is generally represented as a standard Gaussian distribution. Considering the elliptical spots, two‐dimensional (2D) joint Gaussian distribution characterized with the correlation coefficient ρ is adopted in this study. Gaussian‐type particle distribution with white noise was generated and processed in MATLAB to simulate the secondary particle collection in the pixel ion chamber. The simulated pixel ion chamber is a commercially available ion chamber which consists of 12 × 12 small square pixels (3.75 × 3.75 mm2) with a 0.05 mm interval. The simulated signals were preprocessed by filtering with the noise threshold and extracting the maximum simply connected domain (MSCD) of the signal. Then, five geometric parameters that identify the transverse beam profiles were fitted under different signal‐to‐noise ratio (SNR) conditions: the center of the beam (x0, y0), the spot size (σmajor, σminor), and the rotation angle θ formed between the major axes of elliptical spot and the x axes of the ion chamber. First, the simulated signals were preprocessed by filtering with the noise threshold and extracting the MSCD of the signal. Second, a rectification curve of systematic error in fitted spot size versus the prescribed spot size was used to predict the systematic error due to the volume averaging effect. Finally, the effects of fitting errors on therapeutic dose were evaluated in terms of gamma index and relative dose difference. Results: When the SNR is not less than 20 dB, the relative fitting error of spot size and the absolute fitting error of angle θ are less than 1% and 6.1°, respectively. The fitting error of beam center increases with spot size and will not exceed 0.22 mm when spot size reaches up to 12 mm. At a SNR equal to 20 dB, neither cold nor hot spots were presented in dose distribution calculated with the fitted spot parameters. Conclusion: The improved Gaussian fitting algorithm performs well when SNR is not less than 20 dB. This method can effectively distinguish the nominal beam and rotated elliptical beam. An ideal systematic error curve can be predicted and used to correct the fitted spot size, thus eliminating the systematic error due to the volume averaging effect of the pixel ion chamber. The fitting error of spot size cannot be fully corrected, but it is negligible and shows little effect on the overall therapeutic dose. [ABSTRACT FROM AUTHOR]

AgSnO2, as the most potential material to replace AgCdO, is widely used in low-voltage electrical appliances. However, because of the high hardness and poor conductivity of SnO2, AgSnO2 has the problems of processing difficulties and large contact resistance. Based on the first principles of density functional theory, a method is proposed to calculate the electronic structure and mechanical properties of SnO2, SnO22Ce, SnO2–N, and SnO22–Ce–N. By analyzing the energy band, density of states, and elastic constants, the results show that Ce–N co-doped SnO2 has the highest relative conductivity, reduced hardness, and increased ductility and overcome processing difficulty. The doped AgSnO2 contact material was prepared by sol–gel method and powder metallurgy method, and the hardness and electrical properties of the sample were tested. The experimental results show that AgSnO2–Ce–N contacts have higher conductivity, lower contact resistance and arc energy, and lower hardness. The theory is consistent with the experiment, proving the feasibility of simulation. Therefore, Ce and N co-doping can effectively overcome the disadvantages of AgSnO2 contact materials, improve conductivity, and overcome processing difficulty. It provides a new idea and theoretical basis for the doping research of AgSnO2 contact materials. [ABSTRACT FROM AUTHOR]

The mechanism underlying burn injury-induced enhanced vascular endothelial permeability and consequent body fluid extravasation is unclear. Here, the rat aortic endothelial cells (RAECs) were treated with the serum derived from rats with burn injury to elucidate the mechanism. Sprague-Dawley (SD) rats were grouped as follows (10 rats/group): control, 2, 4, 8, 12, and 24 hours postburn groups. The heart, liver, kidney, lung, jejunum, and ileum of rats injected with 2% Evans blue (EB) through the tail vein were excised to detect the EB level in each organ. The serum levels of hypoxia-inducible factor-1α (HIF-1α) and endothelin-1 (ET-1) were examined using enzyme-linked immunosorbent assay (ELISA). The effect of serum from 12-hour postburn group on the membrane permeability of RAEC monolayer, as well as on the mRNA and protein levels of ET-1, endothelin receptor A (ETA), ETB, and zonula occludens (ZO-1), was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting. The membrane permeability of GV230/HIF-1α-transfected or shRNA-HIF-1α-transfected RAECs, as well as the expression levels of HIF-1α, ET-1, ETA, ETB, vascular endothelial (VE)-cadherin, and claudin-5, was analyzed using qRT-PCR and western blotting, whereas the localization of VE-cadherin and claudin-5 was examined using immunofluorescence. The serum HIF-1α and ET-1 levels in the burn groups, which peaked at 12 hours postburn, were significantly upregulated (P < .01) when compared with those in the control group. Additionally, the serum HIF-1α levels were positively correlated with vascular permeability. Compared with the shRNA-negative control-transfected RAECs, the shRNA-II/HIF-1α-transfected RAECs exhibited downregulated expression of HIF-1α, ET-1, ETA, and ETB (P < .01), and upregulated expression of ZO-1, claudin-5, and VE-cadherin (P < .05). Compared with the GV230-transfected RAECs, the GV230/HIF-1α-transfected RAECs exhibited upregulated expression of HIF-1α, ET-1, ETA, and ETB (P < .01), and downregulated expression of ZO-1, claudin-5, and VE-cadherin (P < .05). The GV230/HIF-1α-transfected RAECs exhibited degradation and translocation of VE-cadherin and claudin-5. In addition to degradation of VE-cadherin and claudin-5, HIF-1α mediated enhanced endothelial cell permeability through upregulation of ET-1, ETA, and ETB, and downregulation of ZO-1 and VE-cadherin in rats with burn injury. [ABSTRACT FROM AUTHOR]

A proton therapy facility based on an isochronous superconducting cyclotron is under constructed at the Proton Therapy Facility of the Huazhong University of Science and Technology. Due to the limitation of minimum energy extracted by the energy selection system in the upstream beamline, a range shifter is installed at the end of the nozzle to further decrease the proton beam energy so that the shallow-seated tumors can be treated. In this paper, the physical structure, energy degradation scheme, and material optimization selection of the range shifter are discussed and analyzed by Monte Carlo simulation software Geant4 and FLUKA. At the same time, the treatment outcome on the energy degradation process and its influence on the synthesis of spread-out Bragg peak (SOBP) in the treatment plan system after the application of the range shifter are analyzed. The results show that by using a high-density polyethylene energy-degrading plate with a thickness of 42.35 mm, combined with two 30-mm copper collimators, the range shifter can achieve a good energy-degradation effect while significantly reducing the beam horizontal penumbra at the edge of the radiation field. At the same time, the addition of the range shifter can reduce the number of the energy level required to form the SOBP and shorten the treatment time, but it will inevitably lead to a slight increase in the longitudinal penumbra. [ABSTRACT FROM AUTHOR]

To solve the magnetic field coupling problem in the traditional bearingless permanent-magnet motor, which has magnets on the rotor, we propose two topologies of bearingless switched reluctance motors (BLSRMs) with magnets on the stator yoke. The first is a six/four-pole BLSRM with three pairs of permanent magnets on the stator and the second is a six/four-pole BLSRM with one pair of stator yoke magnets. First, the working principle of BLSRMs is introduced, including the structure and winding configuration, and the mechanism of generating levitation force is analyzed in detail. Based on 2D finite element analysis, the electromagnetic characteristics of the prototype are compared, including torque, suspension force, no-load back EMF, and no-load permanent magnet linkage. The calculation results show that at high speeds, the coupling between the levitation force winding and the torque winding of the BLSRM with one magnet pair is low, which allows for better decoupling performance and greater levitation force. In addition, although the motor with three pairs of permanent magnets in the stator yoke shows better torque performance, the loss of the motor is higher at a high speed. The research results lay a theoretical foundation for further research on a new type of bearingless motors. [ABSTRACT FROM AUTHOR]

For the deficiencies of AgSnO2 contact material, the first-principle based on the density functional theory was used to study the electrical and mechanical properties of pure SnO2, Ni doped SnO2, Mo doped SnO2 and Ni-Mo co-doped SnO2 . The parameters of every model, including the formation energy, energy band structure, density of state, elastic constant were obtained by the CASTEP module of Materials Studio software. According to the formation energy, the doped models can exist stably. After doped, every mode's valence band top and conduction band bottom are at the same point so the doped models are still the direct bandgap semiconductor materials. The Ni-doped SnO2 is P-type doped semiconductor material, and the Modoped is the N-type as well as Ni-Mo co-doped SnO2 . With the introduction of the new impurity levels, the band gap is narrowed. Compared with the band structure of pure SnO2, the doped models have a rising valence band and a declining conduction band so they have a smaller band gap, and the Ni-Mo co-doped SnO2 has the smallest band gap. With the reduced energy for carrier transition, the electrical performance of SnO2 is improved largely. What's more, the shear modulus, volume modulus and hardness are obtained by the elastic constants. The hardness of Ni-Mo co-doped SnO2 decreases significantly and its toughness is enhanced, which is conductive to the subsequent processing and forming of AgSnO2 contact material. The Ni- Mo co-doped SnO2 has the smallest universal elastic anisotropy index so the contact materials are not easy to form cracks. According to the calculation results, it turns out that the co-doping of Ni-Mo can improve the electrical and mechanical properties of SnO2 better than single element doping, which provides theoretical guidance for the further development and research of contact materials. [ABSTRACT FROM AUTHOR]

In this study, the precipitation behavior of MnS was calculated during the solidification process of the medium sulfur, non-quenched and tempered 49 MnVS steel. And the precipitation process was directly observed by a high-temperature confocal laser scanning microscope (HT-CLSM) equipped with a gold-image furnace. Besides, the precipitated particles were proved to be MnS by using the Scanning Electron Microscope-Energy Dispersive spectroscopy (SEM-EDS) analysis. The modified thermodynamic calculation indicated that the MnS precipitated from the residual liquid steel when the product of manganese and sulfur concentrations exceeded the equilibrium value at 1417.0 °C. Meanwhile, the results calculated by FactSage software shown that the beginning precipitation temperature of MnS is about 1411.0 °C. The observation of HT-CLSM demonstrated that the primary solid on the free surface of the liquid steel was visualized at 1485.0 °C during the solidification process (cooled from 1520.0 °C to room temperature with a rate of −30 °C/min). Then, the MnS particles started to form at 1437.0 °C and rapidly grew up into shape on the solid-liquid boundary. And the precipitation of MnS continued to form in a large amount (90% of the total) in the next 10 degrees. The enrichment of Mn and S near the local melt surface may be conducive the MnS formation, which results a higher actual precipitation temperature than the calculated value. [ABSTRACT FROM AUTHOR]

The first-principles method based on density functional theory was used to analyze the impurity formation energies, energy bands, density of states, electron overlap population and elastic modulus of SnO2, SnO2–Ni, SnO2–N and SnO2–Ni–N. SnO2 powders with different additives were prepared by the sol-gel method, and then X-ray diffraction experiments and wettability experiments were carried out. The powder metallurgy method was used to prepare AgSnO2 contacts with different additives. The simulation experiments on hardness, electrical conductivity and electrical contact were carried out. The simulation results show that the conductivity of Ni–N co-doped SnO2 is best, and more impurity levels are introduced into the forbidden band, thereby increasing the carrier concentration, reducing the band gap, and improving the conductivity. The experimental results show that Ni, N doping does not change the structure of SnO2, so doped SnO2 still belongs to the tetragonal system. Ni–N co-doping can better improve the wettability between SnO2 and Ag, reduce the accumulation of SnO2 on the contact surface and reduce the contact resistance. Ni–N co-doped SnO2 has the smallest hardness, improving ductility, molding and service life of the AgSnO2 contact material. [ABSTRACT FROM AUTHOR]

In this paper, we propose a deep-learning-based method using a convolutional neural network (CNN) to predict the volume flow rates of individual phases in the oil–gas–water three-phase intermittent flow simultaneously by analyzing the measurement data from multiple sensors, including a temperature sensor, a pressure sensor, a Venturi tube and a microwave sensor. To build datasets, a series of experiments for the oil–gas–water three-phase intermittent flow in a horizontal pipe, in which gas volume fraction and water-in-liquid ratio ranges are 23.77–94.45% and 14.95–86.97%, respectively, and gas flow superficial velocity and liquid flow superficial velocity ranges are 0.66–5.23 and 0.27–2.14 m/s, respectively, have been carried out on a test loop pipeline. The preliminary results indicate that the model can provide relative prediction errors on the testing-1 dataset for the volume flow rates of oil-phase, gas-phase and water-phase within ±10% with 94.49%, 92.56% and 95.71% confidence levels, respectively. Additionally, the prediction results on the testing-2 dataset also demonstrate the generalization ability of the model. The consuming time of a prediction with one sample is 0.43 s on an Intel Xeon CPU E5-2678 v3, and 0.01 s on an NVIDIA GeForce GTX 1080 Ti GPU. Hence, the proposed CNN-based prediction model, which can fulfill the real-time application requirements in the petroleum industry, reveals the potential of using deep learning to obtain accurate results in the multiphase flow measurement field. [ABSTRACT FROM AUTHOR]

Background: Local tissue damage caused by electrical burns is often deep and severe. High-voltage electrical burns are common in the head, neck and torso areas. These are mostly caused by direct contact with the power supply and are often accompanied by deep injuries of the nerve, blood vessel, muscle, tendon, and bone. We must pay great attention to the clinical treatment of these parts injured by electrical burn. Case presentation: The first case involved a migrant worker who touched a 6-kV high-tension wire when welding steel; this electric shock caused burns in many places. Deep electrical burn wounds were mainly located on the left shoulder and back, characterized by widespread skin and soft tissue defect and bone necrosis. We utilized a lower trapezius myocutaneous flap to repair these wounds in the neck and back caused by deep electrical burns. The flap survived completely and the wound was effectively repaired. The function and shape of the shoulder and back after the restoration were satisfactory. The second case involved a 29-year-old who accidentally touched a high-voltage wire while working and was burned by a 30,000-V electric shock. His wounds were mainly located on the left head, neck, back and left upper limbs. We designed a 30 cm × 12 cm right trapezius myocutaneous flap which completely covered the wound surface; the electrical burn wounds on the neck and back were effectively repaired. After the electrical burn wound was repaired, the neck function returned to normal with a satisfactory shape. Conclusion: The authors report two cases of patients who were burned by high voltage. We used lower trapezius myocutaneous flaps to repair their wounds, which achieved satisfactory clinical results. This study has provided a reliable surgical method for the clinical treatment of deep electrical burn wounds in the neck, shoulders and back. [ABSTRACT FROM AUTHOR]

Controlling the formation of MnS inclusions during solidification influences the mechanical properties and machinability of the resulfurized steel. A coupled segregation–nucleation–growth model was developed by the finite-difference method involving solute redistribution, heterogeneous nucleation and growth kinetics. Laboratory solidification experiments were performed under various cooling rates in resulphurised 49MnVS steel. In this work, the influence of cooling rate on solute redistribution and growth size of MnS inclusions were simulated using the current coupled model, and the calculated results can provide a valuable reference for MnS formation. Increasing of the cooling rate led to early precipitation and refinement of formed MnS inclusions. Based on the simulation results and experimental data, mathematical relationships between the growing size of MnS with the cooling rate in the low ductility temperature region and in the whole solidification were obtained. [ABSTRACT FROM AUTHOR]

For the deficiencies of AgSnO2 contact material, the first-principle based on the density functional theory was used to study the electrical and mechanical properties of pure SnO2, Ni doped SnO2, Mo doped SnO2 and Ni-Mo co-doped SnO2 . The parameters of every model, including the formation energy, energy band structure, density of state, elastic constant were obtained by the CASTEP module of Materials Studio software. According to the formation energy, the doped models can exist stably. After doped, every mode's valence band top and conduction band bottom are at the same point so the doped models are still the direct bandgap semiconductor materials. The Ni-doped SnO2 is P-type doped semiconductor material, and the Modoped is the N-type as well as Ni-Mo co-doped SnO2 . With the introduction of the new impurity levels, the band gap is narrowed. Compared with the band structure of pure SnO2, the doped models have a rising valence band and a declining conduction band so they have a smaller band gap, and the Ni-Mo co-doped SnO2 has the smallest band gap. With the reduced energy for carrier transition, the electrical performance of SnO2 is improved largely. What's more, the shear modulus, volume modulus and hardness are obtained by the elastic constants. The hardness of Ni-Mo co-doped SnO2 decreases significantly and its toughness is enhanced, which is conductive to the subsequent processing and forming of AgSnO2 contact material. The Ni- Mo co-doped SnO2 has the smallest universal elastic anisotropy index so the contact materials are not easy to form cracks. According to the calculation results, it turns out that the co-doping of Ni-Mo can improve the electrical and mechanical properties of SnO2 better than single element doping, which provides theoretical guidance for the further development and research of contact materials. [ABSTRACT FROM AUTHOR]

To examine the aberrant expression of endothelial permeability associated proteins including MLCK, p -MLC and ZO-1 in presence of different levels of hypoxia-inducible factor 1 alpha (HIF-1α). We established monolayer vascular endothelial cell model with the primary rat endothelial cells. Over-expressed or under-expressed HIF-1α cell lines were made by endothelial cells transfected with plasmid vector constructed with HIF-1α gene or HIF-1α-specific short hairpin RNA (shRNA). Levels of mRNA and protein of MLCK, p -MLC and ZO-1 were determined using Real-Time PCR and Western blot. All data were analyzed using by One-Way ANOVA method and LSD. We successfully cultured the rat endothelial primary cells for four days. The mRNA and protein levels of MLCK and p -MLC were significantly increased in the HIF-1α over-expression group than that in the blank control group and the empty plasmid GV230 group (P ＜0.05). ZO-1 was significantly lower in the HIF-1α over-expression group than that in the blank control group and the GV230 group. On the contrary, the mRNA and protein levels of MLCK and p -MLC were significantly lower in the HIF-1α under-expression group than that in the blank control group and the shRNA-NC group (P ＜0.05). ZO-1 was significantly higher in the HIF-1α low-expression group than that in the blank control group and the shRNA-NC group. HIF-1α positively regulates the expression of MLCK and p -MLC and negatively regulates the expression of ZO-1 in rat monolayer endothelial cells. • A large number of transcription factors are involved in various responses of cells and organisms under hypoxic conditions. • Hypoxia inducible factor-1 is considered to be the most important transcription factor that mediates hypoxic response of body. • HIF-1α positively regulates the expression of MLCK and p -MLC and negatively regulates the expression of ZO-1 in rat monolayer endothelial cells.. [ABSTRACT FROM AUTHOR]