Tuning the phase transition of ZnO thin films through lithography: an integrated bottom‐up and top‐down processing

An innovative approach towards the physico‐chemical tailoring of zinc oxide thin films is reported. The films have been deposited by liquid phase using the sol–gel method and then exposed to hard X‐rays, provided by a synchrotron storage ring, for lithography. The use of surfactant and chelating agents in the sol allows easy‐to‐pattern films made by an organic–inorganic matrix to be deposited. The exposure to hard X‐rays strongly affects the nucleation and growth of crystalline ZnO, triggering the formation of two intermediate phases before obtaining a wurtzite‐like structure. At the same time, X‐ray lithography allows for a fast patterning of the coatings enabling microfabrication for sensing and arrays technology.     

Scalable bottom‐up assembly of suspended carbon nanotube and graphene devices by dielectrophoresis

Bottom‐up assembly by dielectrophoresis (DEP) has emerged in recent years as a viable alternative to conventional top–down fabrication of electronic devices from nanomaterials, particularly carbon nanotubes and graphene. Here, we demonstrate how this technique can be extended to fabricate devices containing carbon nanotubes and graphene suspended between two electrodes over a back‐gate electrode. The suspended device geometry is critical for the development of nano‐electromechanical devices and to extract maximum performance out of electronic and optoelectronic devices. This technique allows for parallel assembly of devices over large scale. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Batch versus Flow Photochemistry: A Revealing Comparison of Yield and Productivity

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.     

Conjugated polymer nanoparticles as fluorescence switch for selective cell imaging

Fluorescence switch plays a vital role in bioelectronics and bioimaging.Herein,we presented a new kind of facile electrostatic complex nanoparticles(ECNs)for fluorescence switching in cells and marking of individual cell.The ECNs were prepared by mixing positively charged poly(6-(2-(thiophen-3-yl)ethoxy)hexyl trimethylammonium bromide)(PT)and negatively charged diarylethene sodium salt(DAECOONa).DAE-COONa is a photoswitchable molecule which can be transformed between the ring-closed fo rm and ring-open form under the irradiation of UV or visible light.The closed-form of DAE-COONa can efficie ntly quench the fluorescence of PT through intermolecular energy transfer,while the open form of DAE-COONa does not influence the emission of PT.Thus,the fluorescence of ECNs can be modulated by light irradiation,and the ECNs with good fluorescence switching performance have been employed for fluorescence imaging and individual cell lighting up process successfully.We demonstrate that the electrostatic complex strategy provides a facile method to construct fluorescence switch fo r selective cell marking and imaging applications.     

板式换热器的污堵与清洗及其对能耗的影响

文中从实际应用角度,叙述了板式换热器的特点和基本工作原理,讨论了换热器工作过程中的热阻问题,分析了换热器污堵后对换热性能的影响因素,并探索了解决污堵问题的方法。最后以数据统计的形式,描述换热器污堵和清洗与能耗的关系。实践证明,定期对换热器进行清洗是确保换热器工作性能正常和降低能耗最有效的方法。     

基于LMS算法的自适应控制在稳定回路中的应用

成像器稳定跟踪平台的稳定回路设计是一种高精度、高动态响应的伺服回路设计,为实现较好的控制特性,提出了一种基于LMS算法的Adaline网络参数自适应控制方法,根据被控对象的参数变化,实时调整控制器的参数,由于算法相对简单,满足实际工程应用的要求。为了避免自适应算法运算对系统响应快速性的影响,设计了基于常规控制和自适应控制的双模态控制器结构,根据实际工作条件,进行控制策略的实时切换,既保证了系统响应的快速性,又保证了控制精度。实验结果表明,采用该方法实现的稳定回路具有良好的动态和静态特性。     

基带内插脉冲成形滤波器的FPGA实现

基带内插脉冲成形(BBIPS)滤波器是全数字调制器的核心模块之一.成形滤波运算是调制器中运算量最大的组成部分,因此它的高效实现对降低调制器的运算量有着积极的意义.标准的滤波运算需要大量的乘加操作,然而简单的查表操作就可以实现调制器的基带成形滤波功能.首先介绍BBIPS滤波的理论基础,然后给出用FPGA实现BBIPS滤波器的查找表方法,并详细介绍基于查找表的设计结构.采用该技术实现的全数字BBIPS滤波器不仅性能优越,而且具有很强的灵活性,可以针对不同码元速率、内插倍数、基带成形波形等参数在系统中方便地修改.符合数字通信软件化的趋势,在软件无线电中有广阔的应用前景.     

真三维立体显示静态成像技术研究

简述了二维立体显示的现状,分析了真三维立体显示静态成像技术的基本原理和成像空间材料选取的依据,给出了真三维立体显示系统的控制模型,最后以人体心脏为例实现了真三维立体显示静态成像的模拟,并列举了它在各领域中的应用。     

内蒙古地区沙生植物--沙枣对亚硝酸盐分解作用的研究

利用分光光度法研究了内蒙古地区沙生植物———沙枣对亚硝酸盐的分解作用。结果表明,沙枣中富含的维生素C、维生素E和脯氨酸等抗氧化剂可以作为还原剂与亚硝酸盐作用,从而降低亚硝酸盐的含量;加入的沙枣量愈多,随时间延长对亚硝酸盐的分解能力亦增强,但不呈线性关系。试验结果表明,沙枣不仅可以作水土保持、防沙造林的先锋树种,还由于它富含抗氧化物,可作为人体降低体内亚硝胺生成的良好补充源。     

Er3+/Yb3+共掺杂La2TiO5荧光粉体的制备及上下转换荧光性质研究

使用溶胶-凝胶法制备了Er³⁺单掺及Er³⁺/Yb³⁺共掺La₂TiO₅荧光粉体样品。经过1 100 ℃下3 h的煅烧,得到了较好的微晶。X射线粉末衍射测试表明样品中不含杂质相。扫描电镜观察表明样品颗粒范围为100~300 nm。紫外激发光谱中,在250~320 nm范围内出现Er离子和临近配位氧离子之间强烈的电荷转移跃迁峰,在350~500 nm出现Er离子f-f跃迁尖锐的吸收峰。在378 nm激发下,Er离子发射强烈的特征绿光(546 nm, ⁴S_3/2-⁴I_5/2),当Er离子物质的量分数达到1%,发射峰强度达到最大。在980 nm激发下的上转换光谱中,Yb离子的共掺杂有效的敏化上转换发光强度。详细讨论了样品的上下转换发光机理及相应能量传递过程。同时测试了样品的荧光衰减和量子产率。