Smooth thin film C/diamond membranes with controllable optical band gaps

Mixed phase carbon-diamond films which consist of small grain diamond in an a:C matrix were deposited on polished Si using a radio frequency CH4 Ar plasma CVD deposition process. Ellipsometry, surface profilometry, scanning electron microscopy (SEM) and spectrophotometry were used to analyse these films. Film thicknesses were typically 50-100 nm with a surface roughness of ± 30 A ̊ over centimetre length scans. SEM analysis showed the films were smooth and pinhole free. The Si substrate was etched using backside masking and a directional etch to give taut carbon-diamond membranes on a Si grid. Spectrophotometry was used to analyse the optical properties of these membranes. Band gap control was achieved by varying the dc bias of the deposition process. Band gaps of 1.2 eV to 4.0 eV were achieved in these membranes. A technique for controlling the compressive stress in the films, which can range from 0.02 to 7.5 GPa has been employed. This has allowed the fabrication of thin, low stress, high band gap membranes that are extremely tough and chemically inert. Such carbon-diamond membranes seem promising for applications as windows in analytical instruments. © 1992.

Analysis and simulation of combustion oscillations in a laboratory spray combustor

The unstable combustion that can occur in combustion chambers is a major problem for aeroengines and ground-based industrial gas turbines. Nowadays, CFD provides a flexible, low cost tool to supplement direct measurement. This paper presents simulations of combustion oscillations in a liquid-fuelled experimental rig at the University of Cambridge. Linear acoustic theory was used to describe the acoustic waves propagating upstream and downstream of the combustion zone and to develop inlet and outlet boundary conditions just upstream and downstream of the combustion region enabling the CFD calculation to be efficiently concentrated on the combustion zone. A combustion oscillation was found to occur with its predicted frequency in good agreement with experimental measurements. More details about the unstable combustion can be obtained from the simulation results. The approach developed here is expected to provide a powerful tool for the design and operation of stable combustion systems. Copyright © 2009 by ASME.

Rapid evolution of an X-linked microRNA cluster in primates

MicroRNAs (miRNAs) are a growing class of small RNAs ( about 22 nt) that play crucial regulatory roles in the genome by targeting mRNAs for cleavage or translational repression. Most of the identified miRNAs are highly conserved among species, indicating

Two serine protease inhibitors from the skin secretions of the toad, Bombina microdeladigitora

Two serine protease inhibitors (named BMSI 1 and BMSI 2, respectively) were identified from the skin secretions of the toad, Bombina microdeladigitora. The cDNAs encoding BMSIs were cloned from a cDNA library prepared from the toad skin. The deduced complete amino acid sequences of BMSIs indicate that mature BMSI1 and BMSI2 are composed of 60 amino acids including 10 half-cystines to form 5 disulfide bridges. A FASTA search in the databanks revealed that BMSIs exhibit sequence similarity with other serine protease inhibitors from amphibians of the genus Bombina. BMSI1 potently inhibited trypsin and thrombin with a K(i) value of 0.02 mu M and 0.15 mu M, respectively. Sequence analysis revealed that all serine protease inhibitors from five amphibians of the genus Bombina share highly conserved primary structures. (c) 2007 Elsevier Inc. All rights reserved.

溴隐亭和巴氯芬对吗啡诱导成瘾后戒断症状的协同抑制作用

皮下递增注射吗啡(25、50、75、100、125、150mg/kg)建立小鼠身体依赖动物模型,把6mg/kg纳络酮作用下的小鼠跳跃症状作为成瘾后戒断的行为学观测指标,检测DA受体激动剂溴隐亭和GABAB受体激动剂巴氯芬对戒断行为的影响;同时进一步研究激动二受体在成断过程中的作用.结果表明:溴隐亭低剂量(10mg/kg)无抑制戒断症状的作用,中、高剂量(20、30mg/kg)能够明显抑制戒断症状;巴氯芬低、中剂量(0.5、1.0mg/kg)无抑制戒断症状的作用,高剂量(1.5mg/kg)则可以抑制戒断症状的作用.当无抑制作用剂量的溴隐亭(10mg/kg)和巴氯芬(1.0mg/kg)联合应用时能够明显抑制小鼠的戒断症状,说明此二受体在吗啡成瘾后戒断期间功能上具有协同作用,能够很好地抑制纳络酮诱导的成瘾小鼠跳跃症状.

三峡水库香溪河库湾拟多甲藻昼夜垂直分布初步研究

具鞭毛的拟多甲藻(Peridiniopsis)是三峡水库多数支流库湾春季甲藻水华的优势种类。研究表明,昼夜垂直迁移是鞭毛藻重要的生态学特征。拟多甲藻形态学特征虽然也有鞭毛和自由游泳能力,但至今仍没有关于该种类昼夜垂直迁移的描述。定点昼夜垂直分层研究结果表明,三峡水库甲藻水华暴发的优势种之一拟多甲藻种3(Peridiniopsissp.3)是绝对优势种,相对丰度达到45%;该物种与其它鞭毛藻相似,有昼夜垂直迁移的生态学特征,白天趋于在水体上层聚集分布,晚上趋于在水柱中随机分布;太阳光的昼夜交替是影响拟多甲藻

中国桥弯藻科(硅藻门)的新记录植物

本文报道了采自新疆维吾尔自治区的桥弯藻科(硅藻门)中国新记录植物11种3变种,分别为Amphora mexi-canavar.major(Cleve)A.Cleve,Amphora twenteanaKrammer,Encyonema cespitosumK櫣tzing,Encyonema silesiacumvar.ventriformisKrammer,Cymbopleura albanicaKrammer et Miho,Cymbopleura apiculataKrammer,Cymbopleur

鲫鱼肌肉AChE的提取、纯化及活性研究

以鲫鱼肌肉为原料提取乙酰胆碱酯酶(Acetylcholinesterase,AChE),然后采用改进的Ellman方法按照正交试验设计分别测定不同环境条件(pH值,温度,时间)下粗酶液活性,得到测定AChE活性的最佳条件组合。再将粗酶液依次通过DEAE-Sephadex A-50和Sephadex G-200柱层析纯化。结果表明,3个因素对AChE活性影响的顺序为温度>pH值>时间;最佳酶活性测定条件组合为环境温度35℃,体系pH值8.0,反应时间30 min;经Sephadex A-50柱层析后的纯化倍

鄱阳湖渔业资源现状及其环境监测

1 997— 1 999年对鄱阳湖区渔业资源与环境进行了动态监测 ,统计渔获物 2 778kg,生物学测定 1 62 7尾 ,采集到鱼类 1 2 2种 ,隶属于 1 2目 2 1科 77属 ,其中鲤科鱼类种类最多 ,计 65种 ,占 5 3.3%。湖区渔获物个体偏小 ,以 1— 2龄鱼为主 ,鲤、鲫基本上是当年鱼。鄱阳湖现有鲤、鲫产卵场 33处 ,主要分布在湖区东、南、西部 ,年均有效产卵面积 61 6.66km2 ,年均产卵量5 6.85亿。鄱阳湖区湖口、蛤蟆石、星子、康山水域湖水的pH、COD、Cr+