Quinacridone organic field effect transistors with significant stability by vacuum sublimation

Quinacridone (QA), a highly stable red dye, was investigated for the fabrication of organic field effect transistors (OFETs) by vacuum sublimation. Field effect mobilities for holes of 10^?6 to 10^?3 cm²/Vs were found, depending on the purity of the QA and the substrate temperature during the sublimation. The latter influences the structural phase composition of the films. The temperature dependence of the mobilities exhibits a maximum (μ = (1.5 ± 0.2) × 10^?3 cm²/Vs) at ～270 K. Over a period of 50 days, the mobilities are stable and even slightly increase, although the OFETs were exposed to air between measurements.     

Hybrid 3D-textile reinforced composites with tailored property profiles for crash and impact applications

Novel 3D-textile reinforced composites with a stretched fibre arrangement have very good specific mechanical properties and outstanding energy absorption capabilities. With respect to the specific technical requirements, 3D-textile preforms can be adjusted with regard to stiffness, strength and crash-worthiness by the intelligent combination of different fibre materials in the textile preform. Thus, hybrid 3D-textile preforms with tailored property profiles are excellent candidates for the use in impact and crash components of innovative lightweight structures for the aircraft and vehicle industry as well as for mechanical engineering applications.     

Metamodels in Europe: Languages, Tools, and Applications

Editor's note:This article provides an overview of current efforts in Europe for using metamodeling in the integrated development of critical systems such as automotive electronics. It distinguishes between lightweight versus heavyweight approaches, surveys a number of related current European projects, and gives details about the Speeds project to illustrate the role of metamodeling-driven system engineering.—Sandeep Shukla, Virginia Tech     

High Velocity Oxy Fuel Spraying of Cold Work Tool Steels‐ A Novel Approach to Thick Coatings for Wear Protection Applications

Within this work, HVOF sprayed coatings based on X220CrVMo13‐4 cold work steel were applied to a S235JR construction steel substrate. The investigations focus on the influence of particle size and spray parameters on the coating microstructure, analyzed by means of optical microscope (OM) and scanning electron microscopy (SEM). Additional XRD measurements and micro hardness plots across the interface between substrate material and coating were carried out. Furthermore, the influence of particle size on the detected phases and coating porosity was studied. The results were compared with an X220CrMoV13‐4 reference sample produced by HIP.     

Pretreatment of yellow grease for efficient production of fatty acid methyl esters

Biodiesel is a renewable fuel comprised of fatty acid methyl esters (FAME) derived from vegetable oils or animal fats. Comparisons between biodiesel and petroleum-based diesel have shown biodiesel to be effective in reducing exhaust emissions of carbon monoxide, hydrocarbons, particulate matter, and sulfur dioxide. While there are advantages of biodiesel over the traditional petroleum based diesel, biodiesel commercialization is limited by production cost that is dominated by the price of the feedstock (soybean oil). Yellow grease has the potential to be an effective feedstock with lower cost, but the chemical composition of these oils is variable depending on the source of collection and differs from that of virgin oil due to the presence of free fatty acids (FFA). Esterification has been previously demonstrated to reduce the FFA levels of YG; however, large quantities of methanol were required to drive the reaction to high yield. Methanol usage for processing and FFA content are the main factors affecting the economics of FAME production from YG. In this study, the relationship between composition and process variables was systematically studied. The effect of FFA ranging from 2% to 32% (w/w) was studied at three different molar ratios of methanol to FFA (4.5:1, 9:1, 18:1) and was found to have a non-linear relationship. Data obtained from this full factorial screening was used to develop a predictive statistical model to forecast the conversion based on initial FFA level and proportion of alcohol applied for esterification.     

Low pressure plasma‐based approaches to fluorocarbon polymer surface modification

A survey and comparison of several low pressure plasma‐based approaches to fluorocarbon polymer surface modification is reported including “simple” plasma treatment, “grafting to” and “grafting from” plasma activated surfaces, plasma immobilization of predeposited molecules and the adsorption of charged macromolecules on plasma activated surfaces. Examples of each method are discussed in detail based on results from surface analytical experiments using X‐ray photoelectron spectroscopy, ellipsometry, contact angle goniometry, and electrokinetic measurements. All reported examples refer to one and the same experimental setup. This makes the different approaches comparable and helps to exploit a wide range of plasma‐based techniques for a particular goal and a given apparatus. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 100–109, 2007     

Identification of seven species of the Lactobacillus acidophilus group by FT-IR spectroscopy

Fourier transform infrared (FT-IR) spectra of 102 strains of the seven species of the Lactobacillus acidophilus group were collected and investigated for their potential use in classification and identification on species level. The database built contains more than 370 spectra. Various procedures of pre-processing and classification methods have been compared with respect to their predictive ability. The most encouraging results were achieved with linear discriminant analysis (LDA) of the absorbance values of normalized spectra at selected wavenumbers. The rate of correct species assignment in cross-validation (Jackknife procedure with one spectrum left out for model building) were 95%, 95%, 69%, 100%, 88%, 100%, and 91% for L. acidophilus, L. amylovorus, L. crispatus, L. gallinarum, L. gasseri, L. helveticus, and L. johnsonii, respectively. Very distinct grouping was found for L. gallinarum and L. helveticus, the most difficult differentiation in LDA was between the pairs L. crispatus/L. amylovorus and L. gasseri/L. johnsonii.     

Microstructure Characterization of Cold‐Rolled Dual‐Phase Steels

The evolution of the microstructure of cold‐rolled dual‐phase steels during annealing is investigated. For this purpose, a cold‐rolled dual‐phase grade is annealed in the laboratory. Annealing cycles are applied to systematically investigate various cooling rates and isothermal holding temperatures and times relevant for continuous annealing lines exhibiting an overaging zone. In addition to the characterization of the microstructure by means of light optical metallography and transmission electron microscopy, mechanical properties are presented.     

Impacts on decision making of executives: Probabilities versus outcomes.

The determinants of decision making of executives are of special interest for companies. For a long time choices have been investigated based on theories that assume an equal impact of expected outcomes and expected probabilities (Von Neumann and Morgenstern 1953, Savage 1954, Kahneman and Tversky 1979). The influence of probabilities in decision processes is, however, questioned by a growing body of research (Rottenstreich and Kivetz 2006, Shapira 1995, March and Shapira 1987, 1992). To monitor the information acquisition process of board members and high-ranking executives in the German insurance industry we conducted 51 personal interviews, which included computer-aided simulations. These simulations clearly and objectively support former statements of executives (Shapira 1995) that they focus more on the amount of decision outcomes than on the corresponding probabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)