2-(二硝基亚甲基)-4,5-咪唑烷二酮与甲醇的反应研究

以2-甲基咪唑为原料合成2-(二硝基亚甲基)-4,5-咪唑烷二酮(1), 收率为33.9% (16.8%文献值), 首次采用低碳液态醇实现1的开环反应, 产物为FOX-7. 对反应条件进行了优化, 对比了甲醇、甲酸、氨水三种亲核试剂的开环效果, 开环试剂为甲醇时, FOX-7收率为94.6%, 高于文献值(87.4%). 研究了1的络合性能, 合成了1的甲醇加合物2并进行了结构表征. 对开环反应机理和乙二酰脲的形成机理进行了探讨.     

Determination of nine active components in Radix Hedysari and Radix Astragali using capillary HPLC with diode array detection and MS detection

A capillary HPLC (cHPLC) coupled with diode array detection (DAD) and MS method was developed for the simultaneously qualitative and quantitative determination of nine components, namely vanillic acid, calycosin-7-O-beta-D-glucoside, (6alphaR,11alphaR)-9,10-dimethoxypterocarpan-3-O-beta-D-glucoside, ononin, calycosin, (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside, isoliquiritigenin, formononetin, (3R)-8,2'-dihydroxy-7,4'-dimethoxyisoflavan, in Radix Hedysari (Hongqi) and Radix Astragali (Huangqi). Simultaneous separation of these nine compounds was achieved on a Zorbax C18 microcolumn (5 microm, 150 x 0.3 mm). The mobile phase consisted of (A) 0.3% aqueous formic acid and (B) ACN with a gradient elution. The identification of nine compounds in both Hongqi and Huangqi was confirmed by TOF-MS. All calibration curves showed good linearity (R(2) >0.998) within test ranges. This method showed good repeatability for the quantification of these nine components in Hongqi and Huangqi with intra- and inter-day variations of less than 1.89 and 3.13%, respectively. The validated method was successfully applied to quantify nine investigated components in eighteen samples of Hongqi and Huangqi. Hierarchical cluster analysis of 18 samples was performed using the peak area of nine analytes on cHPLC chromatograms. The result showed that Hongqi and Huangqi are significantly different, though the two species of Astragalus are very similar.     

Effect of Processing and Aging on Particle Size of Explosives

Influence of such processes as molding powder production, pel-lets pressing and aging under different condit/ons on particle size of TATB ( 1,3,S-trlamino-2,4,6-trinltrobenzene ) and HMX (cyclotetramethylenetetranitramine) was experimentally studied. The results showed that parflele size of these explosives was greatly changed before and airier moldinu powder produc-tion, but for different size grade of explosive this change was not the same; pressing process had also great effect on explosive particle size, but before and after ageing process explosive par-tide size did not change seriously.     

FOX-7的合成和反应机理研究

以2-甲基咪唑为原料合成出1,1-二氨基-2,2-二硝基乙烯(FOX-7)并进行了结构表征,从中间体过滤母液中分离出副产物2-甲基-4(5)-硝基咪唑和仲班酸.直接合成的2-甲基-4(5)-硝基咪唑和仲班酸,最佳收率分别为67.3%和63.3%.首次提出了一个较为完整而详细的合成FOX-7的反应机理,硝基重排成亚硝酸酯是反应的关键步骤.FOX-7主要是通过2-甲基咪唑→2-甲基-4(5)-二氢-5-咪唑啉酮→2-(二硝基亚甲基)-5,5-二硝基-4-咪唑烷二酮→2-(二硝基亚甲基)-4,5-咪唑烷二酮→FOX-7步骤形成.论述了各中间体形成的详细过程并进行了证明,应用该机理解释了硝化过程中主产物和副产物的变化规律.     

Influences of excitation power and temperature on photoluminescence in phase-separated InGaN quantum wells

The photoluminescence(PL) properties of a green and blue light-emitting InGaN/GaN multiple quantum well structure with a strong phase separated into quasi-quantum dots(QDs) and an InGaN matrix in the InGaN epilayer are investigated.The excitation power dependences of QD-related green emissions(P_D) and matrix-related blue emissions(P_M) in the low excitation power range of the PL peak energy and line-width indicate that at 6 K both P_m and P_D are dominated by the combined action of Coulomb screening and localized state filling effect.However,at 300 K,P_m is dominated by the non-radiative recombination of the carriers in the InGaN matrix,while P_D is influenced by the carriers transferred from the shallower QDs to deeper QDs by tunnelling.This is consistent with the excitation power dependence of the PL efficiency for the emission.     

Synthesis and properties of potassium 5,5'-azobis (1-nitraminotetrazolate): A green primary explosive with superior initiation power

Potassium 5,5'-azobis(1-nitraminotetrazolate), (K₂ABNAT), a new green primary explosive, was synthesized via a safe and convenient synthetic procedure based on methylcarbazate and cyanogen azide. The compound was characterized by single-crystal X-ray diffraction, IR spectroscopy, Raman spectroscopy, multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). With the calculated (CBS-4M) heat of formation (617.0 kJ/mol) and the room temperature X-ray density (2.11 g/cm³), impressive values for the detonation parameters such as detonation velocity (8367 m/s) and pressure (31.5 GPa) were computed using the EXPLO5 program. The superior calculated energetic performance show it could serve as a green replacement for the widely used primary explosive, lead(II) azide, which contains toxic ingredient.     

Directly extracting both threshold voltage and series resistance from the conductance-voltage curve of an AlGaN/GaN Schottky diode

An Ni/Au Schottky contact on an AlGaN/GaN heterostructure has been prepared. By using the peak-conductance model, the threshold voltage and the series resistance of the AlGaN/GaN diode are simultaneously extracted from the conductance-voltage (G-V) curve and found to be in good agreement with the ones obtained by using the capacitance-voltage (C-V) curve integration and the plot of dV/d(ln I) versus current I. Thus, a method of directly and simultaneously extracting both the threshold voltage and the series resistance from the conductance-voltage curve for the AlGaN/GaN Schottky diode is developed.     

A simple method of extracting the polarization charge density in the AlGaN/GaN heterostructure from current—voltage and capacitance—voltage characteristics

An Ni Schottky contact on the AlGaN/GaN heterostructure is fabricated. The flat-band voltage for the Schottky contact on the AlGaN/GaN heterostructure is obtained from the forward current-voltage characteristics. With the measured capacitance-voltage curve and the flat-band voltage, the polarization charge density in the AlGaN/GaN heterostructure is investigated, and a simple formula for calculating the polarization charge density is obtained and analyzed. With the approach described in this paper, the obtained polarization charge density agrees well with the one calculated by self-consistently solving Schrodinger's and Poisson's equations.     

Stripping extraction calculation and simulation for CYCIAE-100

A 100 MeV H- compact cyclotron is under construction at China Institute of Atomic Energy (CYCIAE-100). The proton beams of 75 MeV-100 MeV at an intensity of 200 μA will be extracted in dual opposite directions by charge exchange stripping devices. The crossing point at the switching magnet center is fixed inside the magnet yoke and the stripping points for various extraction energies are calculated by the code CYCTRS. With the code GOBLIN, we can calculate the transfer matrix including the dispersion effects from the stripping point to the switch magnet. The beam distribution just after stripping foil can be obtained from the multi-particle tracking code COMA and the extracted beam parameters after the switch magnet such as emittance, envelope, dispersion, energy spread, bunch length, etc. are given by the extraction orbit simulations.     

Entropy change in axial symmetric gravitational collapse

We calculate the entropy changes of an imperfect-fluid gravitational collapsing system in the axial symmetric situation, analyzing a practical example. We conclude that the entropy of the collapsing system decreases at the beginning of the collapse and then increases very near the system's horizon.