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The dynamic characteristics of silicon carbide VDMOS (SiC VDMOS) with different bias states under total dose radiation environment were studied. The effects of 60Co γ�ray irradiation on the threshold voltage and switching characteristics of SiC VDMOS with three bias states were compared. The maximum cumulative dose was 100 krad(Si). When the cumulative dose reached 10, 30, 50, 70, and 100 krad(Si), the sensitive parameters were tested by shift test. Annealing at room temperature for 168 h was carried out, and the annealing changes of the three biases were compared. The device used in the experiment was 39 A and 650 V (SCT3060ALHRC11) N�channel SiC VDMOS produced by ROHM Company. The irradiation experiment was carried out in Xinjiang Technical Institute of Physics and Chemistry, Chinese Academy of Sciences. The irradiation source is 60Co, and the dose rate is 50 rad(Si)/s. The sample was irradiated to 100 krad(Si) at room temperature with different biases (Vgs=-5, 0, 20 V, drain and source grounded). Keithley 4200A�SCS semiconductor characteristic analysis system, BC3193 semiconductor discrete device test system, and self�built dynamic test system were selected on the test instrument. The results show that with the increase of 60Co γ�ray irradiation dose, the trapped charge accumulates in the oxide layer, resulting in the decrease of threshold voltage in the static characteristic. Gate oxides in the device accumulate positively charged oxide trap charges. These positively charged defects attract electrons on the semiconductor surface and increase the surface electron concentration, thus reducing the RDS(ON). There are no notable changes in RDS(ON). At the same time, the total ionizing dose radiation does not affect the IGSS, which is consistent with the results of previous studies. It is worth noting that irradiation can shorten the turn�on time slightly, increase turn�off time increases sharply, and the switching loss increases. For this phenomenon, we believe that the change of depletion layer thickness and threshold voltage after irradiation is the main reason for the differential degradation of its turn�on and turn�off response. On the one hand, due to the delay of the Miller platform region, the gate capacitor is charging and discharging during the device’s opening, and the closing process will be slower. The turn�on and turn�off response of the device will be slower and will be prolonged. On the other hand, the reduction of the threshold often makes the channel region of the device enter the anti�pattern region in advance, which makes the device turn on and turn off in advance faster. Further in�depth and detailed research on dynamic radiation damage characteristics is of great significance to ensure the reliability of SiC power devices in a space radiation environment.

The article presents a study which explores about the single-molecule field effect and conductance switching driven by electric field and proton transfer. It mentions that single-molecule junctions (SMJs) offer a novel strategy for miniaturization of electronic devices, along with deciphering the intrinsic properties of matters at the molecular scale.

The article presents a study that explores single-molecule electrical approach for amino acid detection and chirality recognition. It mentions that goals of analytic chemistry as to efficiently discriminate between amino acids. Here we demonstrate this ability using a single-molecule electrical methodology based on molecular nanocircuits formed from stable graphene-molecule-graphene single-molecule junctions.

The article offers information on the electric field–catalyzed single-molecule Diels-Alder reaction dynamics. It mentions that precise time trajectories and detailed reaction pathways of the Diels-Alder reaction as observed using accurate single-molecule detection on an in situ label-free single-molecule electrical detection platform.

The article offers information on the role of ion-exchange inverse loading in the development of surrounded catalysts. It discusses the supported catalyst featuring highly dispersed active phase on support as the most important kind of industrial catalyst. It mentions the demonstrated the critical role of the interfacial interaction/perimeter sites between the active phase and support.

Introduction: The benefit of transanal total mesorectal excision (TaTME) for mid and low rectal cancer is conflicting. Aim: To assess and compare the short-term outcomes of TaTME with conventional laparoscopic total mesorectal excision (LaTME) for middle and low rectal cancer. Material and methods: We searched PubMed, Embase and Cochrane Library databases for studies addressing TaTME versus conventional LaTME for rectal cancer between 2008 and December 2018. Randomized controlled trials (RCTs) and retrospective studies which compared TaTME with LaTME were included. Results: Twelve retrospective case-control studies were identified, including a total of 899 patients. We did not find significant differences in overall intraoperative complications, blood loss, conversion rate, operative time, overall postoperative complication, anastomotic leakage, ileus, or urinary morbidity. Also no significant differences in oncological outcomes including circumferential resection margin (CRM), positive CRM, distal margin distance (DRM), positive DRM, quality of mesorectum, number of harvested lymph nodes, temporary stoma or local recurrence were found. Although the TaTME group had better postoperative outcomes (readmission, reoperation, length of hospital stay) on average, the difference did not reach statistical significance. Conclusions: Transanal total mesorectal excision offers a safe and feasible alternative to LaTME although the clinicopathological features were not superior to LaTME in this study. Currently, with the lack of evidence on benefits of TaTME, further evaluation of TaTME requires large randomized control trials to be conducted. [ABSTRACT FROM AUTHOR]

The article compares the device conductance when molecules connecting single-walled carbon nanotubes (SWNT) switch between states of conjugation. It used electrodes made by excising a nanoscale section from an individual SWNT, which showed a general method to wire a small number of molecules into electrical circuits. It inferred that thiophene-based molecular bridge can be changed from the open to the closed form where pyrrole-based photoswitch can cycle between the open and closed states.

A heterostructure photovoltaic diode featuring an all-solid-state TiO2/graphene/dye ternary interface with high-efficiency photogenerated charge separation/transport is described here. Light absorption is accomplished by dye molecules deposited on the outside surface of graphene as photoreceptors to produce photoexcited electron-hole pairs. Unlike conventional photovoltaic conversion, in this heterostructure both photoexcited electrons and holes tunnel along the same direction into graphene, but only electrons display efficient ballistic transport toward the TiO2 transport layer, thus leading to effective photon-to-electricity conversion. On the basis of this ipsilateral selective electron tunnelling (ISET) mechanism, a model monolayer photovoltaic device (PVD) possessing a TiO2/graphene/acridine orange ternary interface showed ~86.8% interfacial separation/collection efficiency, which guaranteed an ultrahigh absorbed photon-to-current efficiency (APCE, ~80%). Such an ISET-based PVD may become a fundamental device architecture for photovoltaic solar cells, photoelectric detectors, and other novel optoelectronic applications with obvious advantages, such as high efficiency, easy fabrication, scalability, and universal availability of cost-effective materials. [ABSTRACT FROM AUTHOR]

In view of the fact that the catalytic activity of supported catalyst is greatly influenced by its impregnation method, an in situ hydrothermal deposition method was explored and applied to load iron catalyst onto the amorphous carbon matrix, which derived from a soft-templating method with sucrose as precursor, to prepare nanoporous graphitic carbon at low temperature. Compared to traditional impregnation method, this hydrothermal loading method could realize the phase transformation from amorphous carbon to graphitic carbon at a temperature as low as 650°C. Systematical studies on the hydrothermal deposition and catalytic graphitization were made by X-ray diffraction and Raman spectrum, indicating that hydrothermal impregnation temperature and duration are the two crucial factors to the catalytic performance of loaded iron oxide. The obtained graphitic carbon by this approach possesses a nanoporous structure with surface area up to 329m²/g, pore volume of 0.39cm³/g and achieves a capacitance per unit surface area of 39.5µF/cm², much higher than that of the carbon derived from traditional impregnation method (24.6µF/cm²). [ABSTRACT FROM AUTHOR]

The catalytic properties of well-defined hierarchically assembled Bi2WO6 nanoflakes with surface dispersed molybdena have been studied with selective oxidation of propene as probe reaction. The adsorption of oxygen causes the decrease in the conductivity of Bi2WO6, demonstrating its nation of n-type semiconductor. The adsorption of oxygen gains electrons from the conduction band of Bi2WO6 to produce oxygen species active for propene reaction at low temperatures, which, however, gives mainly COx as products. The modification by surface molybdena significantly inhibited the total oxidation reaction of propene over the Bi2WO6, while dramatically increased the conversion of propene and selectivity to acrolein simultaneously, without the formation of acrylic acid. The characterization of conductivity measurements, H2-TPR, O2-TPD, XPS and TPSR indicated that the thermally excited electrons from the Bi2WO6 were combined with surface dispersed molybdena and resulted in an extraordinary increase of selective oxidation performance. The unique effects of the hierarchically assembled Bi2WO6 nanoflakes on the catalytic property of molybdena were discussed and the mechanism of the catalyst for the selectively catalytic oxidation was proposed. The results are useful to design novel catalysts for important reactions with nano concepts. [ABSTRACT FROM AUTHOR]

We report preparation of large area quasi-one-dimensional (1D) monolayer graphene superlattices on a prototypical high-index surface Cu(410)-O and characterization by Raman spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, scanning tunneling microscopy, and scanning tunneling spectroscopy. The periodically stepped substrate gives a 1D modulation to graphene, forming a superlattice of the same superperiodicity. Consequently, the moire pattern is also quasi-1D, with a different periodicity. Scanning tunneling spectroscopy measurements revealed new Dirac points formed at the superlattice Brillouin zone boundary as predicted by theories. [ABSTRACT FROM AUTHOR]

A series of catalysts made of tungsten oxide loaded on SiO2, γ-Al2O3, SiO2-Al2O3 and silica deposited γ-alumina are tested for 1-butene metathesis. Among these catalysts, the catalyst 6W/2OSiO2/Al2O3 gives the highest activity for 1-butene metathesis reaction with 1-butene conversion up to 71 mol% and the yield of propene up to 21 mol%. The excellent catalytic activity is related to the moderate dispersion of tungsten oxide and the suitable acidity of the support. The dispersion of WOx species and the acidity of supports were studied by characterization of XRD, Raman spectra, UV-vis, H2-TPR and NH3-TPD in detail. The surface properties of silica modified γ-alumina leads to the moderate aggregation of supported tungsten oxide, which appears to be more effective for 1-butene metathesis at the low temperature of 453 K. Optimized activity was realized by tuning the dispersion of tungsten species on silica deposited alumina. [ABSTRACT FROM AUTHOR]

Through molecular engineering, single diarylethenes were covalently sandwiched between graphene electrodes to form stable molecular conduction junctions. Our experimental and theoretical studies of these junctions consistently show and interpret reversible conductance photoswitching at room temperature and stochastic switching between different conductive states at low temperature at a single-molecule level.We demonstrate a fully reversible, two-mode, single-molecule electrical switch with unprecedented levels of accuracy (on/off ratio of ~100), stability (over a year), and reproducibility (46 devices with more than 100 cycles for photoswitching and ~105 to 106 cycles for stochastic switching). [ABSTRACT FROM AUTHOR]

Amarusine A (1), a new polyketide derivative possessing an unusual dioxaspiro[4.4]nonane derivative with a butyrolactone ring, was isolated from the leaves of Pleioblastus amarus. The structure and absolute stereochemistry of compound 1 were rigorously determined using UV, IR, HRESIMS, and 1D and 2D NMR techniques and by comparing experimental and calculated electronic circular dichroism (ECD) spectra. Amarusine A (1) exhibits a good antioxidant activity for scavenging the DPPH radical. A possible biosynthetic pathway was postulated. [ABSTRACT FROM AUTHOR]

The article presents the study which describes the synthesis, self-assembly and properties of the contorted hexabezocoronenes (HBC) or nanoscale cable into electrical devices. This material organizes into cables or fibers, in which are ordered both on the molecular scale and on supramolecular scale having an orthorhombic unit cell of 5.8 nm x 4.5 nm x 0.45 nm. Transmission electron microscopy, electron diffraction and powder X-ray diffraction were used to elucidate the structure of the fibers.