Effects of Ce,Sm and Yb on cavitation erosion of NAB alloy in 3.5% NaCl solution

The influences of Ce, Sm and Yb on cavitation erosion of NAB alloy in 3.5% NaCl solution are evaluated using mass loss, SEM, 3D morphology and Tafel plot, respectively. The results show that the addition of Ce or Sm or Yb enhances the mechanical property of NAB alloy, and the sizes of κ_Ⅰ and κ_Ⅱ phases within NAB alloy decrease with adding Ce or Sm or Yb, resulting in the prevention of the propagation of the cracks caused by cavitation erosion initially originated at the phase boundaries between α and κ phases, and finally the cavitation erosion damage significantly decreases with adding Ce or Sm or Yb. The corrosion of NAB alloy in 3.5% NaCl solution can promote the cavitation erosion of NAB alloy, while the corrosion resistance of NAB alloy increases with the addition of Ce or Sm or Yb, and then the cavitation erosion resistance is accordingly improved with the addition of rare earth element.     

新一代的SDV平台

本文主要介绍了BVCOM公司针对广电网的核心业务DVB、VOD、IPTV,于2008底成功推出的新一代SDV平台,文中重点阐述了SDV的创新技术及技术优势,以及公司在借鉴了同行失败及成功的经验基础上,如何突破性扩展了体系应用,真正实现了＂播出、传输、监测、管理＂系统级的解决方案     

NAB对撞增强相位共轭腔快锁模特性

本文分析了NAB[NdAl_3(BO_3)_4]自激活激光晶体脉冲被动锁模的优越性。研究了对撞增强自起动自泵浦近简并四波混频相位共轭腔的形成条件及其在锁模过程中的作用。首次演示了NAB对撞增增强快速压缩脉冲锁模过程。获得了平均7ps的超短脉冲的实验结果。     

四硼酸铝钕晶体及其小型全固态激光器

当前,全固态激光器在向万瓦级大功率方向发展的同时,也在向微型化发展。利用碟片全固态激光器可获得千瓦级以上激光,利用微片全固态激光器则可实现小体积、高密度、中小功率激光输出。获得高功率高密度激光的关键在于激光材料。本文从碟片和微片激光器的发展和对激光基质材料的要求出发,概述自激活激光晶体的研究,特别对四硼酸铝钕[NdAl3(BO3)4,简称NAB]晶体的结构、生长、性质及其作为有应用前景的小型片状激光器的候选材料作了详细的介绍。近期,采用面积为4×4 mm2,厚度为0.39 mm的微片NAB晶体,用885 nm半导体激光器为光源泵浦,获得了4.6 W的1.063 μm激光的有效输出,其斜效率达到64%,充分显示了NAB晶体作为自激活激光晶体在微片激光器中的应用前景。     

NAB97展出的数字HDTV发射管

本文主要论述了英国ＥＥＶ，美国ＶａｒｉａｎｓＥｉｍａｃＤｉｖｉｓｉｏｎ和ＷｅｓｔｉｎｇｈｏｕｓｅＥｌｅｃ－ｔｒｉｃＣｏｒｐ．以及法国Ｔｈｏｍｓｏｎ四家公司在ＮＡＢ９７展示的数字ＨＤＴＶ发射管最新产品：四极管，ＭＳＲ：速调管，ＳｉＣ固态器件，ＩＤＴ和双端四极管Ｄｉａｃｒｏｄｅ的主要技术性能，同时也介绍了上述五种ＨＤＴＶ发射管在数字ＨＤＴＶ发射机中的应用实例。     

四硼酸铝钕晶体及其小型全固态激光器

当前,全固态激光器在向万瓦级大功率方向发展的同时,也在向微型化发展。利用碟片全固态激光器可获得千瓦级以上激光,利用微片全固态激光器则可实现小体积、高密度、中小功率激光输出。获得高功率高密度激光的关键在于激光材料。本文从碟片和微片激光器的发展和对激光基质材料的要求出发,概述自激活激光晶体的研究,特别对四硼酸铝钕[NdAl3(BO3)4,简称NAB]晶体的结构、生长、性质及其作为有应用前景的小型片状激光器的候选材料作了详细的介绍。近期,采用面积为4×4 mm2,厚度为0.39 mm的微片NAB晶体,用885 nm半导体激光器为光源泵浦,获得了4.6 W的1.063μm激光的有效输出,其斜效率达到64%,充分显示了NAB晶体作为自激活激光晶体在微片激光器中的应用前景。     

小型NAB光纤耦合医用激光器

本文报道了以（3×21）mm3的小型脉冲氙灯泵浦（3×21）mm3的NAB晶体的脉冲激光器，通过聚焦系统和光纤耦合组成体积小，重量轻，携带方便的小型光纤耦合医用激光器。     

Influence of the solvent representation on vibrational entropy calculations: Generalized born versus distance‐dependent dielectric model

The harmonic model is the most popular approximation for estimating the “configurational” entropy of a solute in molecular mechanics/Poisson‐Boltzmann solvent accessible surface area (MM/PBSA)‐type binding free energy calculations. Here, we investigate the influence of the solvent representation in the harmonic model by comparing estimates of changes in the vibrational entropies for 30 trypsin/ligand complexes on ligand binding. Second derivatives of Amber generalized Born (GB) solvation models are available in the nucleic acid builder code. They allow one to use these models for the calculation of vibrational entropies instead of using a simpler solvation model based on a distance‐dependent dielectric (DDD) constant. Estimates of changes in the vibrational entropies obtained with a DDD model are systematically and significantly larger, by on average, 6 kcal mol^?1 (at T = 300 K), than estimates obtained with a GB model and so are more favorable for complex formation. The difference becomes larger the more the vibrational entropy contribution disfavors complex formation, that is, the larger the ligand is (for the complexes considered here). A structural decomposition of the estimates into per‐residue contributions reveals polar interactions between the ligand and the surrounding protein, in particular involving charged nitrogens, as a main source of the differences. Snapshots minimized with the DDD model showed a structural deviation from snapshots minimized in explicit water that is larger by, on average, 0.5 Å RMSD compared to snapshots that were minimized with GB^HCT. As experimental vibrational entropies of biomacromolecules are elusive, there is no direct way to establish a solvent model's superiority. Thus, we can only recommend using the GB harmonic model for vibrational entropy calculations based on the reasoning that smaller structural deviations should point to the implicit solvent model that closer approximates the energy landscape of the solute in explicit solvent. © 2012 Wiley Periodicals, Inc.