射流式单重态氧发生器研究

单重态氧O2(a1△g)是迄今唯一能用纯化学反应高效产生的具有长寿命的亚稳激发态分子.为了考察提出的用两个O2(1△)能量汇集反应生成氧第二单重激发态O2(b1∑+g)以实现近可见短波长化学激光方案的现实性,设计和实验了一个氯流量为3～10 mmol/s的射流式单重态氧发生器(JSOG).考察了三种具有不同孔径和孔数目的喷头、氯气流量和脱水冷阱温度等对JSOG出口的O2(1△)浓度、O2(1△)分压、氯利用率及水蒸气含量的影响.发现用聚氯乙烯管作冷阱时,最佳冷阱介质温度为-140～-150℃,对此提出了O2(1△)表面脱活与脱水互相竞争的解释.在最佳条件下,可将O2(1△)气中水分压降低至4 Pa,这一结果是首次报导.     

Photocurrent properties of high—sensitivity GaN ultraviolet photodetectors

GaN epilayers were grown on sapphire substrates by metal-organic chemical vapour deposition. Metal－semiconductor－metal photoconductive detectors were fabricated using this material. The photocurrent properties of the detectors were measured and analysed. The spectrum response shows a high sensitivity in the wavelength region from 330 to 360nm, with a peak at 358nm and a sharp cutoff near 360nm. The maximum responsivities at 358nm were 700A/W (2V) and 7000A/W (30V). The relationship between responsivity and bias indicates that the responsivity increases linearly with bias until 30V. The influence of the spacing between two electrodes on the detector responsivity was also studied.     

In-line phase contrast for weakly absorbing materials with a microfocus x-ray source

For weakly absorbing materials, image contrast can be enhanced by phase contrast in formation. The effectiveness of the in-line phase contrast technique relies on its ability to record intensity data which contain information on the x-ray's phase shift. Four kinds of approaches to the relationship between intensity distribution and phase shift are reviewed and discussed. A micro-focal x-ray source with high geometrical magnification is used to acquire phase contrast images. A great improvement on image quality is shown and geometrical parameters are modified for comparison between different imaging positions.     

锂离子电池过充特性的研究

以尖晶石锰酸锂作锂离子电池正极材料,研究其过充电特性及影响因素.结果表明,电池1C过充特性和正极活性物质的量有关,与负极活性物质的量无关.充电倍率是影响电池过充特性的关键因素,低倍率过充时,结束电池过充的主要原因是内部电解液分解殆尽;高倍率过充时,因电池内部产生的热量增加,散热相对滞后,导致电池内部温度升高隔膜熔断从而截断回路结束过充.     

强外场调控下半导体中浅杂质态的光学吸收特性

理论研究了法拉第位形下强太赫兹激光场、磁场以及压强作用下半导体中浅杂质态非线性光学性质.利用含时非微扰理论——强太赫兹激光场效应被精确包含在激光缀饰库仑势中——和变分法计算出浅杂质态电子能级和波函数,然后基于紧致密度矩阵方法研究强外场和压强对浅杂质态1s→2p_z跃迁的线性、三阶非线性及总的光学吸收系数和折射率变化的影响.研究发现压强和强外场通过激光缀饰库仑势可调控跃迁能和几何因子的增大或减小,所以饱和吸收不但依赖于入射光强和弛豫时间而且还依赖于强外场,在强激光场强度和回旋共振区域附近饱和吸收更容易实现.线性、三阶非线性及总的光学吸收系数和折射率变化的共振峰位置和振幅,在选取合适的外场参数下不但受到强外场的有效调控,而且还受到压强的强烈影响.研究结果为设计强外场调控的新型高效基于杂质电子器件提供了理论支持.     

Altitudinal Variation of Metabolites,Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

Rhodiolacrenulata (Hook.f. & Thomson) H.Ohba is an alpine medicinal plant that can survive in extreme high altitude environments. However, its changes to extreme high altitude are not yet clear. In this study, the response of Rhodiola crenulata to differences in altitude gradients was investigated through chemical, ICP-MS and metabolomic methods. A targeted study of Rhodiola crenulata growing at three vertical altitudes revealed that the contents of seven elements Ca, Sr, B, Mn, Ni, Cu, and Cd, the phenolic components, the ascorbic acid, the ascorbic acid/dehydroascorbate ratio, and the antioxidant capacity were positively correlated with altitude, while the opposite was true for total ascorbic acid content. Furthermore, 1165 metabolites were identified: flavonoids (200), gallic acids (30), phenylpropanoids (237), amino acids (100), free fatty acids and glycerides (56), nucleotides (60), as well as other metabolites (482). The differential metabolite and biomarker analyses suggested that, with an increasing altitude: (1) the shikimic acid-phenylalanine-phenylpropanoids-flavonoids pathway was enhanced, with phenylpropanoids upregulating biomarkers much more than flavonoids; phenylpropanes and phenylmethanes upregulated, and phenylethanes downregulated; the upregulation of quercetin was especially significant in flavonoids; upregulation of condensed tannins and downregulation of hydrolyzed tannins; upregulation of shikimic acids and amino acids including phenylalanine. (2) significant upregulation of free fatty acids and downregulation of glycerides; and (3) upregulation of adenosine phosphates. Our findings provide new insights on the responses of Rhodiola crenulata to extreme high altitude adversity.     

高剂量与高能量离了注入研究进展

综述了离子束材料实验室在高剂量与高能量离子注入研究方面的新进展,包括高剂量离子注入动态靶的模拟计算ＭＡＣＡ程序、多能离子注入深度分布计算、ＭｅＶ离子引起的ＨＯＰＧ表面操作、ＭｅＶ离子诱变右旋糖酐生产菌种、高剂量离子注入在４５号钢表面形成耐腐蚀的保护层以及在高速工具钢上形成含有大量超细碳化物的耐磨层. The development of high dose ion implantation and high energy ion implantation at the Ion Beam Application Group of IHIP in recent years is reviewed.     

单晶变角EPR谱的解释Ⅱ.掺Cr3+乙酰丙酮铝单晶的EPR

对掺Cr³⁺乙酰丙酮铝单晶的(001),(100)和(110)晶面进行晶面旋转EPR扫描,得到共振磁场随旋转角度变化的实验图形,根据本征插方法编写的程序,对实验谱图进行投合,得到下述顺磁参数,D=0.5870±O.005cm^-1,E=-0.00490±0.0001cm^-1,g_x=g_y=1.965±0.001,g₂=1.984±0.001.     

Backstepping control for the optoelectronic stabilized platform based on adaptive fuzzy logic system and nonlinear disturbance observer

A composite controller based on a backstepping controller with an adaptive fuzzy logic system and a nonlinear disturbance observer is proposed in this paper to address the disturbance and uncertainty issues in the control of the optoelectronic stabilized platform. The matched and unmatched disturbances and system uncertainty are included in the stabilized platform model. The system's uncertainty and disturbance are approximated and estimated using an adaptive fuzzy logic system and a nonlinear disturbance observer. Moreover, the backstepping control algorithm is utilized to control the system. The simulations are performed in four states to confirm the viability of the proposed control technique. The proportional integral controller, proportional integral-disturbance observer controller, and fuzzy backstepping controller are contrasted with the proposed controller. It has been noted that the proposed controller's instantaneous disturbance's highest value is 5.1°/s. The maximal value of the coupling output for the two gimbals utilizing the proposed controller, however, is 0.0008°/s and 0.0018°/s, respectively. The findings presented here demonstrate that the backstepping controller, which is based on an adaptive fuzzy logic system and a nonlinear disturbance observer, is capable of precise tracking and dynamic tracking of a stabilized platform under disturbance and uncertainty.

     

脱氢醋酸与氨的反应

脱氢醋酸(1)与氨反应生成2,6-二甲基-4-羟基吡啶(2)^[1]。IguChi等^[2]曾用纸层析法定性地研究了这反应的过程。为进一步了解(1)与氨反应的历程及影响反应的因素,我们用HPLC研究了在不同反应条件下得到的中间体和产物,研究了相互转变关系,并进行了分离和鉴定。初步提出了该反应的可能历程。