对超重、失重演示实验的改进

对传统的超重、失重演示实验进行了改进,使弹簧秤的指针能静止在超重(或失重)的位置上,从而能准确地读出读数,提高演示效果.     

Interdiffusion of hydroxyl groups and of doping additions between a bearing pipe and a deposited layer in billets of fiber light guides

Using Raman spectroscopy, a quantitative analysis of the distribution of OH⁻ ions on the boundary between a bearing pipe and a glass layer deposited from chlorides in billets for quartz fiber light guides is carried out. Water penetrated into the light-reflecting shell to a depth of several tenths of a millimeter, depending on the composition of the doping layer (i.e., ultimately on the temperature of the depsoition process). A. F. Ioffe Physical-Technical Institute, Academy of Sciences of Russia, 26, Politekhnicheskaya St., St. Petersburg, 194021, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 548–550, July–August, 1997.     

哈佛大学有效提升物理教学质量的举措分析

深入探讨了哈佛大学提升物理课程教学质量的举措,诸如卓越的教学方法、全面的教师培养、科学的教学指导、高效的教学评价等.哈佛大学的这些全面、细致、具体、实用的举措对我国大学物理教学质量的提升具有一定的借鉴意义.     

A Versatile Solid-Phase Approach to the Synthesis of Oligonucleotide Conjugates with Biodegradable Hydrazone Linker

One of the ways to efficiently deliver various drugs, including therapeutic nucleic acids, into the cells is conjugating them with different transport ligands via labile or stable bonds. A convenient solid-phase approach for the synthesis of 5′-conjugates of oligonucleotides with biodegradable pH-sensitive hydrazone covalent bonds is proposed in this article. The approach relies on introducing a hydrazide of the ligand under aqueous/organic media to a fully protected support-bound oligonucleotide containing aldehyde function at the 5′-end. We demonstrated the proof-of-principle of this approach by synthesizing 5′-lipophilic (e.g., cholesterol and α-tocopherol) conjugates of modified siRNA and non-coding RNAs imported into mitochondria (antireplicative RNAs and guide RNAs for Mito-CRISPR/system). The developed method has the potential to be extended for the synthesis of pH-sensitive conjugates of oligonucleotides of different types (ribo-, deoxyribo-, 2′-O-methylribo-, and others) with ligands of different nature.     

基于单通道反射型电光调制器实现不同路光同时调制的方法

提出了一种利用单通道反射型聚合物电光调制器同时调制不同路光的方法。衰减全反射结构的电光调制器,其每一个衰减全反射(ATR)峰的位置分别对应于一个导波共振模式。实验系统中利用衰减全反射导膜峰作为调制通道,使其每一路光路的入射角分别对应于不同导波共振模式的工作角,就可以实现利用单通道的电光调制器同时调制不同路光。提出了三种实现两路光同时调制的模式,并给出了三种模式的调制结果。结果表明,作为调制通道的导模阶数越低,调制效率越高。在832 nm光波波长下,采用最低阶导模进行调制时可以获得42.9%的调制效率。     

金属腐蚀监测的光波导传感方法研究

本文提出一种用于金属腐蚀监测的光波导传感方案 ,用金属膜层局部取代光波导的介质包层 ,构成腐蚀敏感膜 ,从而获取金属腐蚀信息 .依据波导理论选用 72 1比色皿上的石英玻璃作为光波导材料 ,利用电化学方法在波导材料内表面上形成Fe C合金腐蚀敏感膜 ,并用XRD、EDX等对膜层结构进行分析 .在电化学腐蚀膜的同时 ,用光学方法记录光波导输出光功率的变化 ,实验结果表明电化学方法与光学方法获取的腐蚀信息同步 ,证实了所提传感方案可行     

Water mist attenuates guided laser based on Monte Carlo method

The round-trip attenuating process of lasers used for guiding in artificial water mists is studied with the Monte-Carlo method. A new way for confirming the scattering directions of photons is established based on calculating Mie cumulative probability distribution function of the polydisperse mist and user defined function fitting by Matlab. Two Monte-Carlo methods for photons tracking are mentioned and their efficiencies are discussed and balanced in this paper. A conclusion is come to that the Wight method is evidently more efficiency than the Event method, and the former is adopted in this paper. The radiuses of frequently-used water mists are usually in the range of 10¹–10² μm which are found to be suited to attenuate the 10.6 μm laser and can be used for laser stealth. But the effect is worse for 1.06 μm laser.     

Mode Distribution and Bandwidth Characteristic of Arbitrarily Trapezoidal-Groove Guide for Millimeter Waves

The modes TE and TM of arbitrarily trapezoidal-groove guide are analyzed by using the mode-matching method. The mode TE₁₁ is the dominant mode of the trapezoidal-groove guide under different conditions. The bandwidth characteristic and the operation condition for the single dominant mode are discussed. The obtained conclusions are of very important significance in theoretical study and practical application of trapeziodal-groove guides for millimeter waves.     

Twisting of a Spinning Particle Trajectory in an Absorbing Medium

In the geometric optics approximation, we predict the effect of additional twisting of spinning particle trajectories in an absorbing medium. The effect is determined by the particle polarization (chirality) and the curvature of the particle trajectory. Using our results, we quantitatively estimate the deviation from the mirror reflection law for ultracold neutrons.     

利用弹簧振子演示李萨如图形

介绍了利用光滑导轨、弹簧振子、高亮发光二极管演示李萨如图形的方法.