离子注入诱导量子阱界面混合效应的光致荧光谱研究

采用多元芯片方法获得了一系列不同离子注入剂量的GaAsAlGaAs非对称耦合量子阱单元,通过光致荧光谱测量,研究了单纯的离子注入导致的界面混合效应.荧光光谱行为与有效质量理论计算研究表明,Al原子在异质结界面的扩散在离子注入过程中已基本完成,而热退火作用主要是去除无辐射复合中心. 关键词： 量子阱 离子注入 光致荧光谱 界面混合     

Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

We report the application of electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) for measurements of nitric oxide concentration ([NO]) in three different atmospheric pressure flames. Visible pump (532 nm) and Stokes (591 nm) beams are used to probe the Q-branch of the Raman transition. A significant resonance enhancement is obtained by tuning an ultraviolet probe beam (236 nm) into resonance with specific rotational transitions in the (v’=0, v”=1) vibrational band of the A²Σ⁺–X²Π electronic system of NO. ERE-CARS spectra are recorded at various heights within a hydrogen-air flame producing relatively low concentrations of NO over a Hencken burner. Good agreement is obtained between NO ERE-CARS measurements and the results of flame computations using UNICORN, a two-dimensional flame code. Excellent agreement between measured and calculated NO spectra is also obtained when using a modified version of the Sandia CARSFT code for heavily sooting acetylene-air flames (φ=0.8 to φ=1.6) on the same Hencken burner. Finally, NO concentration profiles are measured using ERE-CARS in a laminar, counter-flow, non-premixed hydrogen-air flame. Spectral scans are recorded by probing the Q₁ (9.5), Q₁ (13.5) and Q₁ (17.5) Raman transitions. The measured shape of the [NO] profile is in good agreement with that predicted using the OPPDIF code, even without correcting for collisional effects. These comparisons between [NO] measurements and predictions establish the utility of ERE-CARS for detection of NO in flames with large temperature and concentration gradients as well as in sooting environments. PACS 07.88.+y; 42.62.Fi; 42.65.Dr     

Optical characteristics of semiconductor saturable absorber mirrors investigated by the reflection Z-scan technique

Recently, the semiconductor saturable absorber mirror (SESAM) has become a key component of passive mode-locked solid-state lasers. Here we present a simple method based on the reflection Z-scan technique to measure the key optical parameters of SESAM such as saturation fluence and modulation depth. The experimental results demonstrate that our method is able to perform with a high accuracy of 10⁻⁴ and a dynamic range of over four orders of magnitude.     

中国西南武陵山区跳蛛新种记述（蜘蛛目：跳蛛科）

本文记述跳蛛科13个新种,采自西南武陵山地区。暗跳蛛Asemonea、列锡蛛Lycidas和法老蛛Pharacocerus 3属为我国新记录属。     

CAI课件在"摩擦力"教学中的应用

摩擦力是力学中常见的一种力,为了弥补传统教学模式和手段的不足,本人利用几何画板制作了一个课件,在计算机上模拟物体所受摩擦力的形成、方向、大小变化,将静摩擦到滑动摩擦物体的整个受力情况清晰地展现出来,给学生建立起直观的、动感很强的物理图景,解决了教学中难以表达清楚、演示实验也无法演示清楚的问题,取得了较好的效果.     

Identification of peroxyacetic acid uroporphyrin I in the urine of patients with congenital erythropoietic porphyria by liquid chromatography and mass spectrometry

A new porphyrin, peroxyacetic acid uroporphyrin I, has been isolated from the urine of patients with congenital erythropoietic porphyria by reversed phase high performance liquid chromatography. The porphyrin was characterized by high resolution mass spectrometry and by typical chemical reactions of a peroxyacid.     

Synthesis, Characterization and Thermal Decomposition Mechanism of Cetyltrimethyl Ammonium Tetrathiotungstate

The synthesis, characterization and thermal decomposition mechanism of cetyltrimethyl ammonium tetrathiotungstate （CTriMATT） were studied herein. The as-synthesized CTriMATT was characterized by Elemental analysis, X-ray diffraction （XRD）, Fourier transform infrared （FT-IR）, Ultraviolet visible （UV-Vis） spectra. The results showed that the as-synthesized CTriMATT had high purity and good crystallinity. The introduction of alkyl groups induced a shift of the stretching vibration band of W-S bond to lower wavenumber, while it had no influence on the position of WS4^2-. Thermogravimetric analysis （TG）, differential thermal analysis （DTA） and in situ XRD characterizations revealed that CTriMATT began to decompose at 423 K in nitrogen and was converted to WS2 eventually. In addition, the decomposition product of CTriMATT at 673 K in nitrogen was characterized by N2 adsorption （BET） and scanning electron microscopy （SEM）. The results demonstrated that WS2 with higher specific surface area, and pore volume could be obtained from the thermal decomposition of CTriMATT in nitrogen.     

Thermionic emission from giant fullerenes

The kinetics of cluster formation in supersonic jets is examined by numerical integration of the master equation system. Some general characteristics of cluster kinetics could be formulated. Excellent agreement between experimental curves of p-cresol (H₂O)_{0, 1, 2, 3} formation as function of H₂O pressure and the corresponding calculated curves were obtained assuming successive cluster formation. From the kinetic curves, an unambiguous assignment of cluster size was possible which agreed with mass-resolved REMPI measurements. The fit of the rate coefficients shows the formation of p-cresol (H₂O)₁ to be faster than p-cresol (H₂O)₂ and p-cresol (H₂O)₃.     

Quality evaluation of Flos lonicerae through a simultaneous determination of seven saponins by HPLC with ELSD

A new HPLC coupled with evaporative light scattering detection (ELSD) method has been developed for the simultaneous quantitative determination of seven major saponins, namely macranthoidin B (1), macranthoidin A (2), dipsacoside B (3), hederagenin-28-O-beta-D-glucopyranosyl(6-->1)-O-beta-D-glucopyranosyl ester (4), macranthoside B (5), macranthoside A (6), and hederagenin-3-O-alpha-L-arabinopyranosyl(2-->1)-O-alpha-L-rhamnopyranoside (7) in Flos Lonicerae, a commonly used traditional Chinese medicine (TCM) herb. Simultaneous separation of these seven saponins was achieved on a C18 analytical column. The mobile phase consisted of (A) acetonitrile-acetic acid (95:0.5) and (B) 0.5% aqueous acetic acid using a gradient elution of 29%A at 0-10 min, 29-46%A at 10-25 min and 46%A at 25-30 min. The drift tube temperature of ELSD was set at 106 degrees C, and with the nitrogen flow-rate of 2.6 l/min. All calibration curves showed good linear regression (r2>0.9922) within test ranges. This method showed good reproducibility for the quantification of these seven saponins in Flos Lonicerae with intra- and inter-day variations of less than 3.0% and 6.0%, respectively. The validated method was successfully applied to quantify seven saponins in five sources of Flos Lonicerae, which provides a new basis of overall assessment on quality of Flos Lonicerae.     

HPLC–MS Analysis of Isoniazid in Dog Plasma

A simple, rapid, and sensitive liquid chromatography–mass spectrometric (LC–MS) method was developed and validated for the determination of isoniazid in dog plasma. Plasma samples were deproteined with methanol and separated on a C₁₈ column interfaced with a single quadrupole mass spectrometer, using 0.1% formic acid–acetonitrile (91:9 v/v) as mobile phase. Detection was performed by positive electrospray ionization with selected ion monitoring at m/z 138 for isoniazid and 152 for entecavir maleate internal standard. Linearity was obtained over the range of 25–5,000 ng mL^?1, with a lower limit of quantification of 25 ng mL^?1. The intra- and inter-day precision was less than 2.7% in terms of relative standard deviation. Accuracy, expressed as relative error, ranged from ?2.0 to 8.0%. Plasma samples were analysed within 5 min. The method was successfully applied to the evaluation of the pharmacokinetics of isoniazid in dog plasma.