Subsecond adsorption and desorption of dopamine at carbon-fiber microelectrodes

High-repetition fast-scan cyclic voltammetry and chronoamperometry were used to quantify and characterize the kinetics of dopamine and dopamine-o-quinone adsorption and desorption at carbon-fiber microelectrodes. A flow injection analysis system was used for the precise introduction and removal of a bolus of electroactive substance on a sub-second time scale to the disk-shaped surface of a microelectrode that was fabricated from a single carbon fiber (Thornel type T650 or P55). Pretreatment of the electrode surfaces consisted of soaking them in purified isopropyl alcohol for a minimum of 10 min, which resulted in S/N increasing by 200-400% for dopamine above that for those that were soaked in reagent grade solvent. Because of adsorption, high scan rates (2,000 V/s) are shown to exhibit equivalent S/N ratios as compared to slower, more traditional scan rates. In addition, the steady-state response to a concentration bolus is shown to occur more rapidly when cyclic voltammetric scans are repeated at short intervals (4 ms). The new methodologies allow for more accurate determinations of the kinetics of neurotransmitter release events (10-500 ms) in biological systems. Brain slice and in vivo experiments using T650 cylinder microelectrodes show that voltammetrically measured uptake kinetics in the caudate are faster using 2,000 V/s and 240 Hz measurements, as compared to 300 V/s and 10 Hz.     

能谱分析：快速岩石物理解释方法的关键

完井决策需要快速、可靠的测井解释结果。—种新的、几乎能够全自动处理现代能谱测井仪器和常规测井仪器所采集数据的方法,能够为作业者提供这些信息。这种新的解释方法是在对岩心样品的岩石特性与元素含量之间的关系进行大量分析的基础上开发出来的。     

资秩学院单元4 2001-2002年 后农业项目

这个后农业项目的主要目的,是反思在人口密集地区的农业发展问题,农业高产区的荷兰正朝着一种综合且敏锐的机制发展,这种机制对环境和社会可持续的食品供应是非常重要的。这个项目开发的策略,允许农业通过一整套内部系统在不同时间和空间规模上的协作,将自身转换成一种高度综合的、可变的、重要的城市生活程序。     

清凉的绿色：魁北克国立图书馆

加拿大是个拥有众多冰山和地下城市的地方．通常并不因为其建筑上的辉煌成就而闻名于世。各个城市的建筑就像它们的市民一样．向来是非常文雅和朴素的。然而近些年来．考虑到越来越多的都市化、对设计有所了解的民众．加拿大的建筑师已经开始琢磨他们的设计技巧．试图创作出可以给他们带来荣誉的建筑了。     

不能利用等于没有

我是个糟糕的网球手,即使买了昂贵的碳素球拍也帮不了我多大忙。网球与其他许多运动一样,如果不能很好地运用你手中的工具,那么有与没有就没多大区别。这个道理同样适合NOS。例如,Netwale多年来一直支持SMP(对称多处理)。但这对Novell的用户几乎没有任何意义。Sun的Solafis和Microsoft的WindOWS NT的NOS级在文件和Web服务器操作方面都带有附加处理器,但不管机器中是两个还是十个CPU,NetWare的用户数绝不会有任何变     

Web市场硝烟弥漫

每次你连接World Wide Web时,就好象已到达了另外一个地方,它远远超出了Web的原始概念——即提供一种通过浏览器察看静态页的方法。今天,最令人感兴趣的Internet目标是提供动画、声音、视频、定制的内容,或为Web消费者提供在电子空间购买产品的方式。最终结果就是交Web的时代已经露出曙光。 毫无疑问,Netscape Communications Corp.(Navigator的开发商,它拥有浏览器市场80％到90％的份额)企图继续控制将出现的交互Web的发展进度。其HTML扩     

Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.     

源于共同的机械、电气和自动化设计的薄板坯连铸连轧工艺开发

西马克德马格公司在冶金工业方面是一个领先的工业工厂解决方案提供商.统一设计的机械、电气和自动化方案使我们的用户无论是在产品质量、产量、生产的灵活性、工艺的稳定性以及易维护性方面,拥有了生产具有高性能的高级材料的技术.在薄板坯连铸连轧领域,这样的共同开发的例子如下①CSP薄板坯连铸.结晶器液面控制,液压结晶器振动,用于楔形和速度优化的自动导航,带有LCR3(液芯压下)的液压扇形段调整,动态二冷水和结晶器监视系统;②CSP轧机.用于带材板形、连续凸度、平直度控制和自由轧制,采用了特定的磨辊以及相配套的串辊策略的CVC+技术;③用于实现厚度小于1mm带钢高效热轧的"薄规格技术包",包括采用"张力差活套"或"张力计活套"以及快速液压机构配合相应的自动化模块,如自动调平控制,以活套测量为基础的平直度控制,尾部监控或以楔形测量为基础的调平预设定.不仅是机械和电气的共同设计,还有共同的项目执行都将使工厂的运营者受益.例如,对于现代化改造项目和新安装的工厂,通过在交货之前在实验室内的联合测试,项目的投产时间得以优化."工厂回路测试(PILT)"将仿真或甚至机械部件本身与真实的自动化系统(1级,2级和人机界面HMI)结合在一起.通过这样的共同解决方案,西马克德马格公司在电气和自动化领域已发展成"从电机轴一直到生产计划系统"的成套供货商和系统集成商,其目标就是致力于与其用户的长期伙伴关系,并与用户分享其所拥有的工艺经验.     

固体焦平面阵列提高了IR(红外)传感器性能

肖特基势垒的特性红外(IR)传感器在探测、定位、识别和摧毁军事目标的战略和战术系统中起着越来越重要的作用。这类传感器能在无源或配合激光源下工作,激光源能提供极快的速度和精度并能防御强烈的电干扰。为了扩展系统工作性能和经济效益,一些研究所竞相开展固体焦平而阵列(FPA)的研究工作。该阵列以二维凝视模式工作是特别重要的,因     

消除“缝隙”

消除BSS(运营支持系统)和OSS(业务支撑系统)之间的缝隙正在成为电信行业的热门话题。一些人甚至将新的联合到一起的BSS和OSS区域称为B/OSS。这说起来可能有些像轶事,不过行业专家已经开始制定条款了。