Very Low Degree of Energetic Disorder as the Origin of High Mobility in an n‐channel Polymer Semiconductor

Charge transport is investigated in high‐mobility n‐channel organic field‐effect transistors (OFETs) based on poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (P(NDI2OD‐T2), Polyera ActivInk? N2200) with variable‐temperature electrical measurements and charge‐modulation spectroscopy. Results indicate an unusually uniform energetic landscape of sites for charge‐carrier transport along the channel of the transistor as the main reason for the observed high‐electron mobility. Consistent with a lateral field‐independent transport at temperatures down to 10 K, the reorganization energy is proposed to play an important role in determining the activation energy for the mobility. Quantum chemical calculations, which show an efficient electronic coupling between adjacent units and a reorganization energy of a few hundred meV, are consistent with these findings.     

Participatory ergonomics: development of an employee assessment questionnaire

Despite being essential to the success of participatory ergonomics (PEs) programs, there are currently no known quantitative measures that capture the employees’ perspective of PE program effectiveness. The present study addresses this need through the development of the Employee Perceptions of Participatory Ergonomics Questionnaire (EPPEQ). The questionnaire is designed to assess five key components that are based on a review of the available literature: Employee Involvement, Knowledge Base, Managerial Support, Employee Support, and Strain related to ergonomic changes. In Phase 1, a sample of employees and ergonomists working at a manufacturing plant was used to develop and test an initial set of items. In Phase 2, data was collected from a nation-wide sample of employees representing a wide range of jobs and organizations to cross-validate the results from Phase 1. Phase 2 results indicate that the five EPPEQ subscales demonstrate sound convergent validity and are also correlated with traditional indicators of PE program success. Implications and uses of the EPPEQ are discussed.     

Studies on the formation of lysinomethylalanine and histidinomethylalanine in milk products

From reaction mixtures consisting ofN-acetyldehydroaminobutyric acid methyl ester andN -acetyl-l-lysine orN -acetyl-l-histidine, respectively, distinct amounts of the cross-link amino acidsN -(2-amino-2-carboxy-l-methylethyl)-l-lysine (lysinomethylalanine, LMeAL) andN -(2-amino-2-carboxy-1-methyl-ethyl)-l-histidine (histidinomethylalanine, HMeAL) were isolated via preparative ion-exchange chromatography and identified by¹H- and¹³C-nuclear magnetic resonance. In the amino acid chromatogram, both compounds eluted clearly separated from other basic amino acids. However, neither LMeAL nor HMeAL could be detected in numerous acid hydrolysates of a range of milk products. In model studies, threonine showed a significantly lower tendency for an alkali-induced -elimination reaction compared to serine. The reactivity of the resulting dehydroaminobutyric acid towards nucleophiles was more than tenfold lower as compared to dehydroalanine. Thus, the formation of LMeAL as well as of HMeAL during food processing is negligible.

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Studien zur Bildung von Lysinomethylalanin und Histidinomethylalanin in Milchprodukten

Zusammenfassung Aus Reaktionsansätzen bestehend ausN-Acetyldehydroaminobuttersäurenthylester undN -Acetyl-l-lysin beziehungsweiseN -Acetyl-l-histidin konnten die Crosslink-AminosäurenN -(2-Amino-2-carboxy-1-methyl-ethyl)-l-lysin (Lysinomethylalanin, LMeAL) undN -(2 amino-2-carboxy-2 -methyl-ethyl)-l-histidin (Histidinomethylalanin, HMeAL) durch präparative Ionenaustauschchromatographie isoliert und anschließend durch 1H-und¹³C-NMR identifiziert werden. Das Aminosäurechromatogramm zeigte eine eindeutige Trennung beider Aminosäurederivate von anderen basischen Aminosäuren. Dennoch konnten in einer großen Zahl von Säurehydrolysaten der verschiedensten Milchprodukte weder LMeAL noch HMeAL nachgewiesen werden. In Modelluntersuchungen erfolgte die -Elimination an Threonin im Vergleich zu Serin in einem deutlich geringeren Maße. Die Reaktivität der dabei entstehenden Dehydroaminobuttersäure gegenüber Nucleophilen war mehr als zehnfach geringer als die von Dehydroalanin. Damit kann die Bildung sowohl von LMeAL als auch von HMeAL bei der Verarbeitung von Nahrungsmitteln als vernachlässigbar gering eingeschätzt werden.

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Dedicated to Prof. Dr. W. Baltes on the occasion of his 65th birthday     

过程变革中的自相似性

本文试图按照社会技术系统的概念来描述企业，这一概念包括将企业作为一个自相似系统进行建模，这类系统能够不断变化和发展以便达到完成其任务的所有要求，为此目的，有必要对结构和过程的自相似性加以并行考虑，拥有各部门和工作小组的企业结构的自相似性与过程变革的自相似性。     

Microsensor-aided measurements of cellular signalling and metabolism on tumor cells. The cell monitoring system (cms(R))

Microsensors provide instruments particularly suited for the rapid, noninvasive and on-line analysis of cell and tissue cultures. The microsensor system presented in this paper is a modular arrangement of various planar and nonplanar sensor elements for the measurement of physiological parameters of cell cultures. An optic access to the cultures (e.g. for light microscopy and spectrophotometric techniques) is also provided for a parallel and comparative data acquisition. The system was originally designed for biomedical research in chemotherapy (predicative chemotherapy assays) and pharmacology but it turned out to be also an effective tool for toxicological and environmental research.     

Computer aided engineering of automated guided vehicle systems

Automated Guided Vehicle Systems (AGVS) are becoming more and more the main material handling devices in flexible manufacturing systems. The design of an AGVS network is a complex, iterative process. It requires a sequence of geometrical layout drawings and an analytical and computational evaluations. The ability to analyze the AGVS design directly and interactively from the layout drawing would substantially increase the productivity of the design engineer.

A Computer Aided Engineering (CAE) design tool must provide the following three capabilities. First, it must allow the easy, interactive and graphical definition of the system by providing standard drawing symbols and the required operations on those symbols. Second, it must support direct, interactive analysis of the design from within the drafting package. Third, it must provide for the necessary output to interface with off line simulation, analysis and verification programs.

The possibility of extending the prominent CAD packages CADAM and AutoCad to perform CAE of AGVS is examined. A prototype of such a CAE tool has been developed based upon the Autocad package and implemented on a microcomputer. Design and implementation issues, as well as future research areas, will be reported on.