Growth of Ca3Fe2Ge3O12 and Ca3Fe(Al,Cr) Ge3O12 garnets in molten bismuth germanate glasses

Additions of Fe₂O₃ to CaO·Bi₂O₃·2 GeO₂ cause Ca₃Fe₂Ge₃O₁₂ garnets to precipitate from the resultant melt at 1250°C. Garnets with the composition Ca₃Fe(Al, Cr) Ge₃O₁₂ are also precipitated by adding either $\text{Al}{}_2\text{O}{}_3\text{Fe}{}_2\text{O}{}_3$ or $\text{Cr}{}_2\text{O}{}_3\text{Fe}{}_2\text{O}{}_3$ mixtures. The well-formed crystals range from several to 100 μm in size and are obtained in 50 to 70% yields at $\text{Fe}\text{Bi}\text{= 0.4}$. Additions of Fe₂O₃ (up to $\text{Fe}\text{Bi}\text{= 1.0}$) to compositions containing ZnO, CdO, SrO, and BaO yield only dark glasses. The physical properties of these glasses suggest that Fe(III), in contrast to AL(III) & Ga(III), prefers octahedral coordination.     

应用在远程控制系统中的72M2901

本文介绍了单片全双工调制解调器芯片73M2901的基本功能和特点,阐述了73M2901在电话网络远程控制系统中的应用.利用该方案,可在电话网络上进行远程数据传输,实现计算机对现场的远程监控.     

Does ICT promote democracy similarily in developed and developing countries? A linear and nonlinear panel threshold framework

This paper assesses the impact of ICT adoption on democracy for a panel of 70 countries over the period 2000–2017. We consider two different measures of ICT and check for the stability of the relationship for different levels of economic development. Our findings show that both internet and mobile technologies increase the level of democracy in our sample countries. When considering the level of economic development, divergent results are reported for developing and developed countries. Developing countries most commonly have autocratic political regimes where internet and mobile content is monitored by government authorities. More ICT diffusion produces in these cases a negative impact on their level of democracy. Moreover, these countries do not show any presence of a threshold of ICT use necessary to enhance their level of democracy. Our findings however report the presence of a nonlinear relationship in developed countries, suggesting that the effectiveness of ICT in enhancing democracy increases as more users are connected to ICT networks. Our findings also show that unlike developing countries, press freedom and ICT adoption are complementary in developed countries. That is, when developed countries are better endowed with ICT, they can enhance the freedom of their press and therefore their level of democracy.     

俄罗斯改进PBB-CД与PBB-MД空空导弹

介绍了俄罗斯两种新型空空导弹PBB-CД中程空空导弹与PBB-MД近程空空导弹的主要改进,并与美国相应导弹型号进行了对比.最后,对这两种导弹的市场前景进行了分析.     

PIC单片机的特点及应用

介绍了Microchip公司的PIC单片机PIC16C73的结构特点和工作原理,给出了用PIC1673设计智能售电系统中PIC通信通道的硬件系统电路和系统软件的设计方法。     

新型高度集成化的视频字符叠加系统的研究

在传统视频字符叠加系统的基础上，利用了Microchip公司推出的单片机PICl6C73和NEC公司推出的专用字符叠加芯片uPD6453，开发了一种新型高度集成化的视频字符叠加系统，详细论述了该字符叠加系统的工作原理、硬件电路设计以及软件设计。该系统已在实践中得到成功应用，是视频字符叠加的一种较好的选择方案。     

基于PIC的后备式UPS的实现

介绍了PIC16C73B单片机和它的特点。分析了后备式UPS的基本原理。并结合PIC16C73B给出了一种后备式UPS实现的实例。文章对后备式UPS设计中的关键参数及其处理方法进行了详细介绍。并且根据硬件设计框图,具体分析了后备式UPS的逆变过程和相关的软件编程。     

NOA73材料的曲面微透镜阵列的制作

为了实现生物复眼的光学性能,介绍了一种仿生物复眼结构通过使用光刻胶熔融法和NOA73(norland optical adhesive)紫外曝光固化技术。首先采用光刻胶熔融法将一系列具有不同曲率、宽度的平面微凸透镜制作在Si基底上,且微透镜阵列具有统一的聚焦特性和光滑度;通过比较NOA73、PDMS两种平面微透镜阵列的聚焦效果,得到NOA73材料具有更好的光学性能;然后利用PDMS的柔韧特性和NOA73紫外曝光固化的特性制作出曲面微凸透镜阵列;最后对曲面微透镜阵列进行成像测试、光强分布测试,结果表明,通过上述工艺制作的曲面微凸透镜阵列,最后对曲面微透镜阵列进行成像测试、光强分布测试,可知通知这种工艺制作的曲面微透镜阵列的尺寸达到微米,光学性能优秀,透光率基本达到100%,具有很好的重复性,可行性且制作简单、快速和低成本,并能模仿复眼结构的部分光学特性。     

Microstructural characterization of AP40 apatite-wollastonite glass-ceramic

The microstructure of an apatite-wollastonite (code name AP40) glass-ceramic is analyzed in this study by combining 2D microscopy, phase analysis, X-ray absorption and synchrotron X-ray refraction computed tomography (XCT and SXRCT, respectively). It is shown that this combination provides a useful toolbox to characterize the global microstructure in a wide scale range, from sub-micrometer to millimeter. The material displays a complex microstructure comprising a glassy matrix with embedded fluorapatite and wollastonite small crystals. In this matrix, large (up to 200 μm) spike-shaped structures are distributed. Such microstructural features are oriented around a central sphere, thereby forming a structure resembling a sea urchin. A unique feature of SXRCT, in contrast to XCT, is that internal interfaces are visualized; this allows one to show the 3D distribution of these urchins with exceptionally good contrast. Furthermore, it is revealed that the spike-shaped structures are not single crystals, but rather composed of sub-micrometric crystals, which are identified as fluorapatite and diopside phases by SEM-EDX analysis.