Optimization of direct modulation rate for circular microlasers by adjusting mode Q factor

Semiconductor microcircular lasers have been investigated as potential light sources for photonic integrated circuits and optical interconnections for more than two decades. However, the direct modulation bandwidths of the circular microlasers remain a challenge, especially when being compared with other microlasers, such as photonic crystal lasers. In this paper, microcircular lasers connected to an output waveguide are investigated for high‐speed direct modulation with optimized mode Q factors. Small signal modulation with a resonance frequency of f_R = 12.5 GHz is realized for a AlGaInAs/InP circular microlaser with a radius of 10 µm at 290 K. Furthermore, clear eye diagrams are observed at 12.5 Gbit/s for a 15‐µm radius circular microlaser with f_R = 6.9 GHz.     

基于Gm-APD的成像激光雷达目标探测特性

针对采用盖革模式雪崩光电二极管（Gm-APD）作为探测器的成像激光雷达,介绍了其测距原理及3D成像原理,并对如何提高其探测性能的方法进行了分析。以分析Gm-APD触发信号的统计特性为基础,对出现在距离门内不同位置目标的探测概率和虚警概率进行了研究与仿真,结果表明,目标处在距离门最前面时,探测概率受噪声水平影响最小,虚警概率受信号强度影响最大;目标靠近距离门中间位置时,探测概率随噪声水平增大下降缓慢,虚警概率随信号强度增大下降缓慢;目标处在距离门末尾时探测概率受噪声水平影响最大,而虚警概率几乎与回波信号强度无关。     

电弧蒸馏光谱法测定地球化学样品中银及其他痕量元素的研究进展

发射光谱法因具有多元素同时测定,分析速度快,灵敏度高,检出限低,使用方便的特点,被用于地质样品中银及其他痕量元素的测定。随着我国地质勘查事业的发展和地球化学调查工作力度的加大,对覆盖区的多目标地球化学调查样品的测试及质量控制提出了更高的要求。同时分析方法和测试技术有了新的进展。基于蒸馏原理的电弧光谱测试技术也有了多方面的进展。本论文归纳总结了国内主要刊物上所发表的电弧蒸馏光谱法测定地球化学样品中银及其他痕量元素的研究和应用情况,重点就固体缓冲剂的组成成分进行简要概述,以期为今后样品测试提供参考。     

A novel carbon source coated on C-LiFePO<Subscript>4</Subscript> as a cathode material for lithium-ion batteries

The poor electronic conductivity and low lithium-ion diffusion are the two major obstacles to the largely commercial application of LiFePO₄ cathode material in power batteries. In order to improve the defects of LiFePO₄, a novel carbon source polyacrylonitrile (PAN), which would form the hierarchical porous structure after carbonization, is fabricated and used. This work comes up with a simple and facile carbothermal reduction method to prepare porous-carbon-coated LiFePO₄ (C-LiFePO₄-PC) composite and to study the effect of carbon-coated temperature on ameliorating the electrochemical performance. The obtained C-LiFePO₄-PC composite shows a high initial discharge capacity of 164.1 mA h g^?1 at 0.1 C and good cycling stability as well as excellent rate capacity (49.0 mA h g^?1 at 50 C). The most possible factors that improve the electrochemical performance could be related to the enhancement of electronic conductivity and the existence of porous carbon layers. In a word, the C-LiFePO₄-PC material would become an excellent candidate for application in the fields of lithium-ion batteries.     

利多卡因醇质体的制备及其透皮性能评价

为了提高酰胺类局部麻醉药利多卡因的经皮渗透量,采取乙醇注入法制备了利多卡因醇质体,正交实验得到其最优制备工艺:卵磷脂与利多卡因质量比1∶1,乙醇体积分数40%,温度30℃,超声时间3min.该法制得利多卡因醇质体的平均包封率为(75.93±5.07)%.将该醇质体制成含裸药5%的凝胶,皮肤刺激性实验和体外透皮实验结果显示该凝胶对豚鼠皮肤无刺激性、无致敏性.该凝胶6h的体外累计渗透量为241.968μg.cm-2,6h的渗透速率(40.331μg.cm-2.h-1)为裸药凝胶渗透速率的7.71倍.     

神经元电生理学等效电路模型及参数特性研究

从考虑神经元轴突朗飞结的电缆模型入手,根据脑磁图和电磁场理论的“场路一致性”原理,讨论了应该从著名的Hodgkin-Huxley一阶静态等效电路扩展为二阶动态电路的合理性和必要性,并通过具体的计算实例进一步研究电生理学材料参数膜电容C 和电感L的频率特性,实验结果表明,有髓神经元纤维轴向信号传递速度越快,其电容和电感值就越小.     

Physical and Chemical Characterization of Therapeutic Iron Containing Materials: A Study of Several Superparamagnetic Drug Formulations with the β-FeOOH or Ferrihydrite Structure

The effectiveness of therapeutically used iron compounds is related to their physical and chemical properties. Four different iron compounds used in oral, intravenous, and intramuscular therapy have been examined by X-ray powder diffraction, iron-57 Mössbauer spectroscopy, transmission electron microscopy, BET surface area measurement, potentiometric titration and studied through dissolution kinetics determinations using acid, reducing and chelating agents. All compounds are nanosized with particle diameters, as determined by X-ray diffraction, ranging from 1 to 4.1 nm. The superparamagnetic blocking temperatures, as determined by Mössbauer spectroscopy, indicate that the relative diameters of the aggregates range from 2.5 to 4.1 nm. Three of the iron compounds have an akaganeite-like structure, whereas one has a ferrihydrite-like structure. As powders the particles form large and dense aggregates which have a very low surface area on the order of 1 m²?g^?1. There is evidence, however, that in a colloidal solution the surface area is increased by two to three orders of magnitude, presumably as a result of the break up of the aggregates. Iron release kinetics by acid, chelating and reducing agents reflect the high surface area, the size and crystallinity of the particles, and the presence of the protective carbohydrate layer coating the iron compound. Within a physiologically relevant time period, the iron release produced by acid or large chelating ligands is small. In contrast, iron is rapidly mobilized by small organic chelating agents, such as oxalate, or by chelate-forming reductants, such as thioglycolate.

     

NDT of the Shape of a Thin 3D Slit on the Metal Surface by Millimeter Waves

As the basis of the evaluation of nature cracks, a millimeter wave method to evaluate the shape of a thin 3D slit on the metal surface is demonstrated. An open-ended coaxial line sensor was proposed to improve the spatial resolution of the measurement. The amplitude of the reflection coefficient that is associated with the dimensions of the slit is measured by scanning the specimen in the direction perpendicular to the detected slit. A characteristic signal corresponding to the detected slit was obtained and, was used to evaluate the depth of the slit.     

基于PC机的一种多功能声显微镜及可视化技术的研究

近来研制成功了一种基于ＰＣ机、我们称为“ＴＨＳＡＭＭ”型的多功能声显微镜。在ＰＣ机内插入采样率１ＧＳＰＳ的超高速Ａ／Ｄ卡和信号产生和接收卡,利用软件完成信号检测、处理、显示功能。仪器工作频率为１－１００ＭＨｚ;在检测样品时,同时多层显示Ａ、Ｂ、Ｃ扫描结果。根据声学理论、Ｍａｒｃｈｉｎｇ Ｃｕｂｅ等值面抽取方法和ＯｐｅｎＧＬ技术完成了三维数据的可视化处理,显示样品的内部三维结构。该系统已成功应用于多