A novel route to synthesize libraries of quinoxalines via Petasis methodology in two synthetic operations

This Letter reveals an innovative and facile procedure to prepare quinoxalines in two synthetic steps. The microwave assisted Petasis reaction is followed by the acid mediated unmasking of an internal amino nucleophile, cyclodehydration and oxidation to give collections of quinoxalines in good to excellent yields.     

Microwave assisted one-pot tandem three-component synthesis of2,4,5-triary1-2-4-dihydro-3H-1,2,4-triazol-3-one derivatives

This work described a one-pot tandem three-component synthesis of 2,4,5-triaryl-2,4-dihydro-3H- 1,2,4-triazol-3-ones using a simple reaction between phenylhydrazines, benzaldehydes and phenyl isocyanates under microwave irradiation and solvent-free conditions in good to excellent yields.     

A rapid approach for the copper,amine, and ligand-free Sonogashira coupling of 4-methyl-7-nonafluorobutylsulfonyloxy coumarins under microwave irradiation

A rapid, efficient, and reliable access for the synthesis of an assortment of 4-methyl-7-alkyl/aryl/heteroaryl alkynyl coumarins has been developed by the copper, amine, and ligand-free Sonogashira cross-coupling reaction of 4-methyl-7-nonafluorobutylsulfonyloxy coumarin with various terminal alkynes under microwave irradiation. In the presence of a suitable catalyst, base, and solvent, the coupling reaction proceeded smoothly to give the diaryl alkynes in satisfactory to exceptional yields. Nonaflates coupled more efficiently than the corresponding triflates which yielded the detriflated product as well as the hydrolyzed product as competing side products along with the required product. The utilization of TBAF·3H₂O as a mild base as well as a solvating agent was the key for success of the reaction.     

A new large – Scale synthesis of magnesium oxide nanowires: Structural and antibacterial properties

Large-scale one-dimensional magnesium oxide (MgO) nanowires with diameters of 6 nm and lengths of 10 μm have been successfully synthesized by a new facile and simple reaction. This production was performed via a microwave hydrothermal approach at low temperature growth of 180 °C for 30 min. The structure of as synthesized MgO nanowires were investigated by means of X-ray diffraction (X-ray), Fourier Transformation Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED) and Energy Dispersive X-ray (EDS). The antibacterial behavior of MgO nanowires concentration in solid media against Gram negative and Gram positive for different bacteria has been tested in details. The results show that the MgO nanowires have bacteriostatic activity against Escherichia coli and Bacillus sp. The antibacterial activity increases with increasing MgO nanowires concentration. Furthermore, the presence of one-dimensional MgO nanowires has high antibacterial efficacy and damages the membrane wall of bacteria. Finally, this study offered the prospect of developing ultrafine nanoscale devices utilizing MgO nanowires and implementing their useful potential in biological control.     

Development of a new type of electric off-road vehicle powered by microwaves transmitted through air

Needless to say, we are now facing a critical state in the global environment, i.e. global warming. We have to change our way of thinking and our economic systems from those dependent on fossil resources to those dependent on renewable energy resources, such as solar energy. In our field of research, electric vehicles are considered the best choice for reducing carbon dioxide emissions. A battery is not an adequate energy source for electric vehicles, because batteries quickly get depleted because of its low energy and power density. A fuel cell is a more favorable alternative to the battery; however, it has large mass and can only replace the internal combustion engine, but the power transmission mechanisms are still necessary. The new concept of an electric off-road vehicle proposed here is entirely different from those mentioned above. The vehicle has neither a combustion engine nor a battery but only electric motors. Energy to drive the motors is transmitted through air as microwaves at 2.45 GHz. This technology was developed at the Research Institute for Sustainable Humanosphere, Kyoto University, as a method for transmitting electricity from a large-scale solar power station (SPS) orbiting in space to the Earth. We have constructed some models of electric off-road vehicles and investigated their adoptability to microwave power transmission. In this paper, some experimental results on the use of microwave power transmission for powering the vehicles are presented, and some problems such as low energy transmission efficiency are also discussed.     

Microwave detection of molecules formed by shock wave induced reactions

The paper describes experimental investigations in a shock tube concerning the formation of new molecules using He as a driver gas and a mixture of Kr, CH and NH as driven gas, where Kr serves as diluant. By microwave absorption technique it was possible to detect HCN, CHO and CHNH as reaction products. Obviously, these molecules were formed in the plasma behind the shock wave. In addition, the “swan bands” of C have been observed with optical methods. Received 16 November 1997 / Accepted 7 May 1998     

Enhancement of energy efficiency for mechanical production of fine and ultra-fine particles in comminution

This paper presents the energy requirements for mechanical production of fine and ultra-fine particles in comminution. Recent approaches for effective size reduction and energy saving in comminution are described, viz., （a） development and application of new mills/classifiers, （b） adjustment of the bead characterization in stirred bead mills, （c） hybrid comminution systems with roller-press and media mill, （d） assisted methods, and （e） simulation.2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.     

Superluminal propagation and information transfer: A statistical approach in the microwave domain

Signal velocity is calculated in a medium with negative group delay (NGD). By accounting for the medium and the detector noise sources, the time varying probability of error at the detector [Pe(t)$\mathit{Pe}(t)$] is evaluated in the NGD channel and a normal dispersion channel. The scheme in which Pe(t)$\mathit{Pe}(t)$ falls below a threshold at earlier time, implies faster information transfer. It is found that the signal velocity depends on the detector type and the relative noise strength of the detector with respect to the channel. Finally, it is shown that NGD channels can be useful in applications that are limited by the detector noise.     

The effect of an external signal on output microwave power of a low-voltage vircator

This Letter is devoted to results of the both experimental and theoretical studies of electromagnetic radiation output power gain in the low-voltage microwave generator with a virtual cathode (vircator) under an external harmonic signal leading to the preliminary velocity modulation of the electron beam. The simple theoretical model of the electron beam with virtual cathode in a diode gap with retarding field under the external signal has been developed. The theoretical and numerical analysis have shown the possibility of power amplification in the vircator under the external influence. Obtained results of the theoretical consideration are proven by the experimental study.     

《微波技术与天线》教学的研究与探讨

通过对《微波技术与天线》这门课的特点与主要内容的分析,针对传统教学中出现的一些问题提出了相应的改革措施。对该课程的教学方式、教学方法等方面进行了探讨与研究。实际教学效果证明,该系列改革措施增加了学生的学习兴趣和热情,教学效果良好。