Applications of single-atom catalysts

Owing to unsaturated coordination environment,quantum size effect and metal-support interaction,single-or dual-atom metal sites,such as Mn,Fe,Co,Ni,Cu,Zn,Mo,Ru,Rh,Pd,Ag,Sn,Ir,Pt,Au,Bi,and Er coordinated with nonmetallic elements such as O,N,P,and S,exhibit different electronic configurations,which endow them with high catalytic performances in multiple redox reactions and versatile applications in organic synthesis,environmental remediation,energy conversion,and biomedicine.Despite intense research,the relation of structure-activity for single-atom catalysts(SACs)still bedazzles researchers,since diversified configurations of active sites would bring about difficulty in structural identification and theoretical simulations.Here,recent results on the applications of SACs are reviewed with an emphasis on identifying the active sites and discussing the relation between structure and property.     

朋友

正像往年新年一样,收到了许许多多同事、同仁、朋友、合作者的祝福短信和贺卡。短信的词汇或长或短,或转发或原创,斑斓多彩,丰富感人,让人温暖兴奋,看不释眼;贺卡或豪华或简朴,或来自遥远的异地,或来自咫尺的近邻,让人感到其中的牵挂、祝福,爱不释手。不论老友新朋,见字如人,回味绵长。我越来越觉得,看短信比看春晚更热切,更有意义,更令人慰藉。特别是在寒冷的冬天里,在全球的危机     

春节特别奉献2012

辞旧迎新,一年一度的春节很快就要来临,在此,我们提前给读者拜年,祝大家新春快乐,合家幸福,万事如意。春节前夕,采办年     

宠物也需“标准生活”

“我睡觉的时候,只要一关灯,抱抱就会出现在枕头边上,我掀开被子,抱抱就钻进来,转个身,紧紧靠着我睡,脑袋枕在我胳搏上,两手还伸开,跟我睡得一模一样。大冷天的,这样的肉麻很让人陶醉。有一次,我躺下的时候抱抱在吃夜宵,等他反应过来,我已经躺踏实了。他跑过来,仔细看了看我,确认我双眼紧闭呼吸均匀,以为我睡着了——其实我是故意的,要搁以前,他会叫两声,把我喊醒重睡。可这次,他竟然没言声,自己在被子上踩了个坑,躺下了。这不就是懂事么？我忍都忍不住,伸手就把他薅进被窝。”     

编委风采

潘复生1962年7月生,浙江兰溪人,工学博士,教授,博士生导师,重庆市科学技术研究院院长,国家镁合金材料工程技术研究中心主任,国家973项目专家组组长,国务院学位委员会学科评议组成员,日本千叶大学客座科学家,英国伦敦大学访问教授。     

普通砖混住宅结构设计经验谈

一、结构设计总说明 　　主要是设计依据,抗震等级,人防等级,地基概况及其承载力,防潮层做法,活荷载取值,材料强度等级,施工中的注意事项,选用详图,通用详图或节点,以及在施工图中未画出而通过说明文字来表达的信息.……     

胜达集团

胜达集团有限公司总部在杭州市萧山经济技术开发区,集团自1983年建厂以来,抢抓机遇,锐意改革,走出了一条“从包强包,多业并举”的科学发展之路,目前,全集团拥有总资产逾25亿元,净资产超20亿元,员工6000多名,形成了以纸包装为主业,涉及纺织,生活用纸,房地产,化工,钢构及物流保税等跨地区,跨行业,集科,工,贸为一体大型企业集团公司,2007年,全集团完成产值46.08亿元。     

涡阳警方端掉两个传销窝点10人被刑事拘留

正2013年12月26日凌晨4时,安徽省涡阳县公安局经侦大队会同城区派出所、县工商局、综治办等单位共计150余人,在前期缜密侦查的基础上,统一行动、雷霆出击,前往西郊孙楼居委会清查了11处传销人员居住的出租屋,一举打掉两个大型传销窝点,现场查获涉嫌传销人员80余人,截至目前,共刑事拘留犯罪嫌疑人10名,治安拘留6名。经查,自2012年6月以来,江苏省丰县李某伙同湖南省株洲易某等人,以销售湖北省武汉某品牌化妆品为名,以每套产品4100元的价格,采用欺诈、诱骗、拉人头等方式,将     

今秋月饼包装闲谈

岁岁中秋年年过,一年更比一年“火”。上海街头,无论是大超市,还是食品店,都争先恐后推出月饼专柜,放眼包装,更是千姿百态,大开眼界。纸盒、铁盒、钙塑盒、铝盒、不锈钢盒、中密度板盒、竹编盒、红木盒。琳琅满目、气象万千,至于内衬丝绒,大盒装小盒、纸盒套铁盒,甚至镶金嵌银也屡见不鲜。报载,广州某居民收到一盒“巨无霸”月饼,     

听殷承宗的钢琴协奏曲《黄河》

“风在吼,马在叫,黄河在咆哮,黄河在咆哮……” 太熟悉了,这气势磅礴的呐喊,这昂扬斗志的旋律,早在1939年春天就已经响彻云霄,传遍弥漫着抗日烽火的中华大地。由光未然作词、人民音乐家冼星海作曲的《黄河大合唱》,曾激励过多少抗日儿女奔赴前线,浴血奋战,保卫家乡,保卫黄河。     

Beam shaping design for coupling high power diode laser stack to fiber

A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible.     

激光沉积高温氧化物超导薄膜

本文简要介绍激光沉积技术的原理、特点及国外科研机构采用这种方法制作陶瓷氧化物高温超导薄膜的技术参数等。本文还探讨了激光沉积超导薄膜的形貌及激光束与靶材的交互作用情况,并展望了这种技术的应用前景。     

镀铬/高能束复合表面处理研究进展

根据高能束对镀铬涂层及其界面强化机制的不同,镀铬/高能束表面复合技术可分为两类:高能束强化镀铬涂层复合技术和高能束预处理基体/镀铬复合技术.前者典型代表有激光表面强化或等离子体氮化/镀铬涂层;后者主要代表是激光预淬火基体/镀铬复合表面处理.综合阐述了上述3种典型的复合处理技术的原理、目的及实际综合效果;通过试验初步探讨了激光预淬火基体/镀铬复合技术延长镀铬身管寿命的主要机理.     

高精度激光准直技术的研究（一）

论述了激光准直技术的发展及共性的技术关键问题，系统介绍了对单位在高精度激光准直技术方面的研究成果，从理论到实践较好地克服激光漂移，大气环境对激光准直的严重影响。研制成功的激光光纤准直仪，激光双频同轴度仪及激光旋光准直仪具有当前高精度激光准直技术的代表性，并且均达到国内外先进水平。     

Local Thermal Fixing of a Photorefractive LiNbO(3) Hologram by use of a CO(2) Laser

A real-time, in situ fixing method by use of heating with a CO(2) laser beam is suggested for thermal fixing of a small local hologram in the bulk of a Fe:LiNbO(3) photorefractive crystal. For heating up to 100 degrees C-200 degrees C a volume with a shape similar to that of the laser beam a heat-guiding technique is developed. On the basis of the heat-transfer equations, different heating modes-with or without metal absorbers for heat guiding-obtained by use of a continuous or pulsed laser beam are analyzed. The optimal mode may be pulsed heating with absorbers. On this basis experiments have been designed and demonstrated. It is seen that the fixing process with CO(2) laser beam is short compared with the process by use of an oven, and the fixing efficiency is quite high.     

A novel technique to measure laser beam spot sizes

In this letter we report a novel technique to measure small laser beam spot sizes. We use the open aperture z-scan technique as a tool to measure the laser beam spot size. This technique measures small spot sizes with accuracy better than 10%.     

Nanosecond and femtosecond mass spectroscopic analysis of a molecular beam produced by the spray-jet technique

The spray-jet molecular beam apparatus enabled us to produce a molecular beam of non-volatile molecules under high vacuum from a sprayed mist of sample solutions. The apparatus has been used in spectroscopic studies and as a means of molecular beam deposition. We analyzed the molecular beam, consisting of non-volatile, solvent, and carrier-gas molecules, by using femtosecond- and nanosecond- laser mass spectroscopy. The information thus obtained provided insight into the molecular beam produced by the spray-jet technique.     

Ground-to-Satellite Narrow-Laser-Beam Pointing by Use of a Backscattered Image

A technique for transmitting a narrow laser beam from a ground station to a satellite has been developed. The principle of pointing a laser beam to a distant target in a scattering medium by use of a backscattered laser beam image is described. We calculated the intensity distribution of the image by using a typical model of atmospheric coefficients. The method was applied to transmit a laser beam from a ground station to Engineering Test Satellite-VI. The accuracy of pointing the laser beam to the satellite was approximately 10 murad in this experiment.     

Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality

An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed.     

Optimal beam size for light delivery to absorption-enhanced tumors buried in biological tissues and effect of multiple-beam delivery: a Monte Carlo study

Optimal laser light delivery into turbid biological tissues was studied by using Monte Carlo simulations based on the delta-scattering technique. The goal was to deliver efficiently the maximum amount of optical power into buried tumors being treated while avoiding potential damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding normal tissue because of selective uptake of the absorption-enhancement dye. The power delivering efficiency to buried tumors was investigated for various diameters of the laser beam. An optimal beam diameter was estimated to achieve the maximum product of the power coupling efficiency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single-beam delivery and multiple-beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumor could be achieved.