无溶剂中性条件下分子I2或Fe(NO3)3·9H2O/NaI原位生成的I2催化醇与甲酸甲酰化反应

 Different alcohols were formylated by formic acid under solvent-free conditions in the presence of iodine as the catalyst with good-to-high yields at room temperature. I₂ generated in situ from Fe(NO₃)₃·9H₂O/NaI also catalyzed the formylation of the alcohols under solvent-free conditions. This gives a green and efficient reaction at room temperature, in which the use of toxic and corrosive molecular I₂ is avoided.     

Performance assessment of nanoscale Schottky MOSFET as resonant tunnelling device: Non-equilibrium Green’s function formalism

A comprehensive study is performed on the electrical characteristics of Schottky barrier MOSFET (SBMOSFET) in nanoscale regime, by employing the non-equilibrium Green’s function (NEGF) approach. Quantum confinement results in the enhancement of effective Schottky barrier height (SBH). High enough Schottky barriers at the source/drain and the channel form a double barrier profile along the channel that results in the formation of resonance states. We have, for the first time, proposed a resonant tunnelling device based on SBMOSFET in which multiple resonance states are modulated by the gate voltage. Role of essential factors such as temperature, SBH, bias voltage and structural parameters on the feasibility of this device for silicon-based resonant tunnelling applications are extensively studied. Resonant tunnelling appears at low temperatures and low drain voltages and as a result negative differential resistance (NDR) is apparent in the transfer characteristic. Scaling down the gate length to 6 nm increases the peak-to-valley ratio (PVR) of the drain current. As the effective SBH reduces, the curvature of the double barrier profile is gradually diminished. Therefore, multiple resonant states are contributed to the current and consequently resonant tunnelling is smoothed out.     

A benchmark study on uncertainty of ALICE ASH 1.0, TALYS 1.0 and MCNPX 2.6 codes to estimate production yield of accelerator-based radioisotopes

Radioisotopes find very important applications in various sectors of economic significance and their production is an important activity of many national programmes. Some deterministic codes such as ALICE ASH 1.0 and TALYS 1.0 are extensively used to calculate the yield of a radioisotope via numerical integral over the calculated cross-sections. MCNPX 2.6 stochastic code is more interesting among the other Monte Carlo-based computational codes for accessibility of different intranuclear cascade physical models to calculate the yield using experiment-based cross-sections. A benchmark study has been proposed to determine the codes’ uncertainty in such calculations. ¹⁰⁹Cd, ⁸⁶Y and ⁸⁵Sr production yields by proton irradiation of silver, rubidium chloride and strontium carbonate targets are studied. ¹⁰⁹Cd, ⁸⁶Y and ⁸⁵Sr cross-sections are calculated using ALICE ASH 1.0 and TALYS 1.0 codes. The evaluated yields are compared with the experimental yields. The targets are modelled using MCNPX 2.6 code. The production yields are calculated using the available physical models of the code. The study shows acceptable relative discrepancies between theoretical and experimental results. Minimum relative discrepancy between experimental and theoretical yields is achievable using ISABEL intranuclear model in most of the targets simulated by MCNPX 2.6. The stochastic code utilization can be suggested for calculating ¹⁰⁹Cd, ⁸⁶Y and ⁸⁵Sr production yields. It results in more valid data than TALYS 1.0 and ALICE ASH 1.0 in noticeably less average relative discrepancies.