Although voltammetry has proved an important tool for unraveling the dynamics of specific neurotransmitter molecules during the past decade, it has been very difficult to monitor more than one neurotransmitter simultaneously. In this work, we present a voltammetric methodology that allows discrimination between dopamine and serotonin, two important neurotransmitter molecules with very similar electrochemical properties, in the presence of high concentrations of ascorbate. We combined the application of a novel large-amplitude/high-frequency voltage excitation with signal processing techniques valid for the analysis of nonstationary and nonlinear phenomena. This allows us to minimize the contribution from capacitance and preserve the faradaic features of the voltammetric response providing us with excellent voltammetric detail. Using appropriate voltage excitation parameters and defining specific regions in the voltage space, so-called voltage windows, we can measure the concentrations of dopamine and serotonin separately or independently in mixed solutions even in the presence of high concentrations of ascorbate. Because of the enhanced voltammetric detail of this new technique, it is also possible to explore effects attributed to interfacial phenomena such as adsorption/desorption and electrode fouling. 相似文献
Reviews the book, Meeting Movies by Norman N. Holland (see record 2006-11509-000). Meeting Movies is a very personal book in which Holland discusses eight films that have been personally meaningful to him. These films are Casablanca, Vertigo, The Seventh Seal, Freud, Persona, Children of Paradise, Shakespeare in Love, and 8 1/2. Holland describes what he was doing with his life when he saw each of these films, and he discusses how each film affected his life and his career. Some of the movies were seen relatively recently, and some were first viewed over half a century ago. In reading the book, it becomes apparent that Holland loves films. Whenever text is in Roman type, Holland is operating in his reader-response critic mode, and the discussion reads much like any other film criticism. However, the most interesting parts of the book occur when Holland is in free association mode, writing about whatever thoughts the movie being discussed brings to mind. These instances are set off from the regular text by use of italicized text. In summary, Meeting Movies is a good read. Holland is well versed in psychology and especially psychoanalytic approaches, and his criticism of these eight films is consistently interesting. His willingness to self-disclose makes this book all the more fascinating. The book will be rewarding for anyone genuinely interested in the interface of psychology and film. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
Liquid chromatography (LC) was coupled on-line to a continuous-flow enzymatic assay using electrospray ionization mass spectrometry (ESI-MS) as readout for the screening of enzyme inhibitors in complex samples. Inhibitors were detected by changes in the concentration of the enzymatic reaction products, indicating the inhibition of enzymatic activity. The molecular masses of the inhibitors were determined with high certainty by using retention time matching and peak shape comparison. Due to the high matching accuracy, baseline separation of coeluting analytes was not necessary in order to identify the correct masses of the bioactive compounds. The continuous-flow system was successfully applied for the screening of complex samples, such as natural extracts. For a red clover extract, detection limits of 0.3-0.8 micromol/L were obtained. System validation was performed by determining the IC(50) values of four inhibitors in the flow-injection mode. The IC(50) values were in the 0.11-5.6 micromol/L range and correspond closely to data obtained by microtiter plate assays. Detection limits were in the range of 0.018-0.35 micromol/L in the flow-injection mode, and 0.075-0.75 micromol/L in the LC mode. These values are well below the typical compound concentrations (1-10 micromol/L) used in high-throughput screening. Together with an interday precision of 12.6%, these results demonstrate the applicability of the system for bioactivity screening of complex mixtures, generating both chemical and biological information on bioactive compounds in a single run. 相似文献
Past editions of the American Association of State Highway and Transportation Officials (AASHTO) Guide for Design of Pavement Structures have served well for several decades; nevertheless, many serious limitations exist for their continued use as the nation’s primary pavement design procedures. Researchers are now incorporating the latest advances in pavement design into the new Mechanistic-Empirical Pavement Design Guide (MEPDG), developed under the National Cooperative Highway Research Program (NCHRP) 1-37A project and adopted and published by AASHTO. The MEPDG procedure offers several dramatic improvements over the current pavement design guide and presents a new paradigm in the way pavement design is performed. However, MEPDG is substantially more complex than the AASHTO Design Guide by considering the input parameters that influence pavement performance, including traffic, climate, pavement structure and material properties, and applying the principles of engineering mechanics to predict critical pavement responses. It requires significantly more input from the designer. Some of the required data are either not tracked previously or are stored in locations not familiar to designers, and many data sets need to be preprocessed for use in the MEPDG. As a result, tremendous research work has been conducted and still more challenges need to be tackled both in federal and state levels for the full implementation of MEPDG. This paper, for the first time, provides a comprehensive bird’s eye view for the MEPDG procedure, including the evolvement of the design methodology, an overview of the design philosophy and its components, the research conducted during the development, improvement, and implementation phases, and the challenges remained and future developments directions. It is anticipated that the efforts in this paper aid in enhancing the mechanistic-empirical based pavement design for future continuous improvement to keep up with changes in trucking, materials, construction, design concepts, computers, and so on.