Influence of branching on the properties of poly(ethylene terephthalate) fibers

A series of branched poly(ethylene terephthalate) samples was prepared by employing 0.07–0.42 mol % trimethylolpropane (TMP) for melt polycondensation. These polymers were characterized with respect to molar mass, intrinsic viscosity, and melt viscosity. Spinning into fibers took place at spinning speeds ranging from 2500 to 4500 m/min. The molecular orientation of the fibers as measured by birefringence and polarized fluorescence decreases with growing amounts of TMP, as does crystallinity. Thus with slightly branched polymers, higher spinning speeds than with a linear polymer can be used to achieve a certain property profile. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 728–734, 1999     

Effect of promoters for n-butane oxidation to maleic anhydride over vanadium–phosphorus‐oxide catalysts: comparison with supported vanadia catalysts

The oxidation of n-butane to maleic anhydride was investigated over model Nb‐, Si‐, Ti‐, V‐, and Zr‐promoted bulk VPO and supported vanadia catalysts. The promoters were concentrated in the surface region of the bulk VPO catalysts. For the supported vanadia catalysts, the vanadia phase was present as a two‐dimensional metal oxide overlayer on the different oxide supports (TiO₂, ZrO₂, Nb₂O₅, Al₂O₃, and SiO₂). No correlation was found between the electronegativity of the promoter or oxide support cation and the catalytic properties of these two catalytic systems. The maleic anhydride selectivity correlated with the Lewis acidity of the promoter cations and oxide supports. Both promoted bulk VPO and supported vanadia catalysts containing surface niobia species were the most active and selective to maleic anhydride. These findings suggest that the activation of n-butane on both the bulk and supported vanadia catalysts probably requires both surface redox and acid sites, and that the acidity also plays an important role in controlling further kinetic steps of n-butane oxidation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Control of low fe content in the preparation of semi-insulating InP by wafer annealing

A reproducible technique for preparing semi-insulating (SI) InP by high temperature annealing can only be achieved by controlled doping with Fe in a sufficient concentration for compensation. However, a successful and reproducible method to adjust the low Fe content has not been developed up to now. In this paper, we report two different experimental approaches to control the Fe content by using either precompensated starting material or an Fe source for doping via the vapor phase. InP wafers (2′ diam) which were lightly predoped with Fe ([Fe] < 5 × 10¹⁵ cm⁻³) during liquid encapsulated Czochralski (LEC) growth were converted from the semiconducting to the SI state and were subsequently analyzed by laterally resolved resistivity measurements. These wafers show high resistivity uniformity (p ≈1 × 10⁸ Ω-cm) which has never previously been achieved with LEC material at such a low Fe concentration. Furthermore, we present the first results of annealing nominally undoped InP with a defined Fe source.     

Strategies to improve the geometric accuracy in asymmetric single point incremental forming

Asymmetric incremental sheet forming (AISF) is a manufacturing process for the small batch production of sheet metal parts. In AISF, a sheet metal part is formed by a forming tool that moves under CNC control. AISF currently has two dominant process limits: sheet thinning and a limited geometric accuracy. This paper focuses on the latter limit. It is shown with a pyramidal part that multi-stage forming can yield an increased accuracy compared to single-stage forming. However, due to residual stresses induced during forming, the accuracy of the as-formed part can be lost if the part is trimmed after forming. A case study with a car fender section shows that the geometric accuracy of the final part can be improved compared to single-stage forming by a combination of multi-stage forming and stress-relief annealing before trimming.     

Role of expectancy timing and outcome consistency in expectancy-guided retrieval.

Two studies investigated how expectancy-timing and expectancy-outcome consistency affect expectancy-guided retrieval. Ss were given a student's grade report for later recall. During the retention interval, Ss' expectancies about the student's future performance (improve vs decline) were manipulated. The expectancy information was presented either at the beginning (T1), halfway through (T2), or at the end of the retention interval (T3). Ss then received outcome information, half consistent and half inconsistent with their expectancy. In both studies, T2 and T3 Ss showed evidence of expectancy-guided retrieval, recalling consistent information accurately but displaying expectancy-congruent distortion of inconsistent information. T1 Ss showed no evidence of expectancy-guided retrieval and accurately recalled both inconsistent and consistent information. Further analyses suggested that T1 Ss appeared to reprocess the original information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The psychoanalytic theory of depression: Symptoms as a function of aggressive wishes and level of field articulation.

Relatively undifferentiated, field-dependent (FD) individuals, in contrast to relatively differentiated, field-independent individuals, are assumed to cope by using introjection. Consistent with the psychoanalytic theory that depression related to object loss results from introjected anger, it was expected that only FD individuals would display symptoms of depression in response to aggressive wishes. It was also expected that FD individuals would show greater physiological reactivity due to their characteristic tendency toward direct affective discharge. 60 undergraduates were divided according to field-articulation scores on the rod-and-frame test, and each S received tachistoscopic presentations of either an aggressive or a neutral stimulus. Measures of mood, self-esteem, and autonomic arousal were used to assess Ss' response to the stimulus. Results indicate that FD Ss displayed a greater degree of depressive feelings irrespective of the type of stimulus with which they were presented. No significant differences were found with regard to self-esteem, and differences for autonomic arousal were not consistent. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Backward masking as a measure of attention in schizophrenia.

Compared backward-masking functions for 2 groups of 16 schizophrenics with the masking functions for 2 control groups (8 undergraduates and 8 nonschizophrenic psychiatric patients). Masking functions were obtained for both single-letter and 8-letter visual displays. The procedure involved a forced-choice letter recognition method analogous to signal detection methodology. Both schizophrenic groups produced longer masking functions, under all conditions, than the 2 control groups whose functions were highly similar. Consistent with "attention" theories of schizophrenia, results indicate that some deficit occurs in schizophrenia at a very early stage of information-processing in the visual system. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Manufacturing dish shaped rings on radial-axial ring rolling mills

Ring rolling is an established method to produce seamless rings of different cross-sectional geometries. For dish shaped rings, there are applications in different areas such as offshore, aeronautics or the energy sector. At the moment, dish shaped rings are produced by machining of rings with rectangular shaped cross section, by (open die) hollow forging on a conical mandrel or by using shaped ring rolling tools. These ways of manufacturing have the disadvantage of high material waste, additional costs for special tools, long process time and limited or inflexible geometries. Therefore, the manufacturing of dish shaped rings on conventional radial-axial ring rolling mills would expand the range of products for ring producers. The aim of this study is to investigate the feasibility of an alternative to the current manufacturing processes, without requiring additional tooling and material costs. Therefore, the intended formation of dish shaped rings—previously regarded as a form error—is investigated. Based on an analysis of geometrical requirements and metal flow mechanisms, a rolling strategy is presented, causing dishing and ring climbing by a large height reduction of the ring. Using this rolling strategy dish shaped rings with dishing angles up to 18° were achieved. In addition to the experiments finite element method (FEM)—simulations of the process have been successfully conducted, in order to analyze the local strain evolution. However, when the contact between ring and main roll is lost in the process the ring starts to oscillate around the mandrel and neither dishing nor ring climbing is observed.     

Information processing by schizophrenics when task complexity increases

Compared the performance of 30 paranoid schizophrenics, nonparanoid schizophrenics, and tuberculosis patients (controls) in a VA Hospital on motor, perceptual, and cognitive tasks of increasing complexity. The data are examined within the context of comparing differential predictions made by input and central processing theories of information-processing deficit. Results indicate that paranoid schizophrenics were comparable to nonschizophrenics in the amounts of information they could process, while nonparanoid schizophrenics reached a stage of information overload with tasks of relatively less complexity. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)