An Investigation of Wax Patterns for Accuracy Improvement in Investment Cast Parts

In this paper, a methodology is proposed that makes use of computer-aided heat transfer simulation and experimentally derived factors for injection parameters, to predict wax pattern shrinkages in the investment casting process. The focus is on developing techniques for the early determination of optimum injection parameters to be used for wax pattern production so that resulting shrinkage can translate into an overall improvement in accuracy of the investment casting process.     

Electrical,mechanical, and piezoresistive properties of carbon nanotube–polyaniline hybrid filled polydimethylsiloxane composites

The electrical, mechanical, and piezoresistive properties of ternary composites based on elastomeric polydimethylsiloxane (PDMS), carbon nanotubes (CNTs), and polyaniline (PANI) were studied and compared with those of binary PDMS–CNT composites. The presence of PANI affected the percolating network of the CNTs. At lower PANI concentrations (2.5 and 5%), the conductive network of the CNTs was constructively modified; this led to an enhancement in the conductivity in the sample containing 2% CNTs. A higher PANI content (7.5%) hindered the flow of main charge carriers through the composite. The piezoresistive response of the binary and ternary composites was studied by cyclic experiments under compression loads. In all of the samples, the electrical resistance increased monotonically up to a 10% strain. The reproducibility of the piezoresistive behavior in the binary and ternary composites provided evidence that the fillers could reversibly recover their initial position together with the PDMS chains without a significant displacement with respect to their original positions. The reduction of the piezoresistive sensibility by PANI addition was attributed to the displacement restrictions of the CNTs within the composite under pressure because of the volume exclusion of PANI particles; this maintained the probability of CNT contact and increased the possibility of the formation of new CNT conductive channels. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44780.     

Naturalistic action impairment in closed head injury.

The authors sought to determine whether errors of action committed by patients with closed head injury (CHI) would conform to predictions derived from frontal lobe theories. In Study 1, 30 CHI patients and 18 normal controls performed routine activities, such as wrapping a present, under conditions of graded complexity. CHI patients committed more errors even on the simplest condition; but, except for a higher proportion of omitted actions, their error profile was very similar to that of controls. Study 2 involved a subset of patients whose performance in Study 1 was within normal limits. When these high functioning patients were asked to perform the routine tasks under still more taxing conditions, they, too, committed errors in excess of the control group. Accounts based on frontal mechanisms have a difficult time explaining the overall pattern of findings. An alternative based on limited-capacity resources is suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression and memory narrative type.

Research with autobiographical memories has distinguished between memory narratives of specific events and summaries of many events blended together. Depression has been associated with a reduced ability to retrieve and orally relate specific positive memories. This study explored the hedonic bias in memory through collection of written autobiographical memories from 90 nonclinical college students whose mood was assessed for depression. Participants with higher depression scores recalled significantly more summary memories in response to a request for a positive self-defining memory than did participants with lower depression scores. There were no significant differences in the number of single-event and summary memories when participants were asked for a negative memory. We used J. A. Singer and K. H. Moffitt's (see record 1992-33945-001) scoring system to distinguish between summarized and specific memory narratives. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examination of North American bison saliva for potential plant growth regulators

A series of laboratory bioassays were utilized to test for the presence of potential plant growth factors in saliva from a large native ungulate, the North American bison (Bison bison L.). Whole saliva enhancedAvena coleoptile growth at high pH, whether alone or in combination with indoleacetic acid (IAA). However, this enhancement was a result of salts in the saliva (primarily NaHCO₃) rather than of other compounds acting hormonally, enhancing IAA activity, or inhibiting IAA oxidase activity as possibly occurs with some insect salivas. Additionally, the absence of detectable cytokinins in the saliva was indicated by its failure to enhance cucumber cotyledon expansion. This suggests that biochemical control of plant growth by salivary compounds following grazing is probably not an important component of this ruminant's interactions with its food plants, as has been suggested for some herbivores.     

Differential attitudes of international students toward seeking professional psychological help.

175 students representing 75 countries completed the Attitudes Toward Seeking Professional Help scale. Of the variance in total attitude, 23% was predicted from the variables age, sex, continent, educational level, time in US, and prior contact with mental health treatment. Prior contact and continent were the most important determinants, with Western (European?+?Latin) attitudes significantly more positive than non-Western (Asian?+?African). Three factors emerged: Confidence/Appropriateness, Stigma/Privacy, and Coping Alone. Prior contact subgroups were discriminated using the dimensions. The most highly significant factor was Confidence/Appropriateness, which suggests that Ss inexperienced with professional help perceived it as a nontrustworthy, inappropriate means for solving personal difficulties. Ss least concerned with the social stigma and invasion of privacy associated with treatment (the Stigma/Privacy dimension) were those who had received help in native countries. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction: The nuclear revolution

Research conducted by the NRC Office of Nuclear Regulatory Research in structural mechanics for reactor technology is reported in this paper. This research concerns applications to mechanical and structural systems and includes materials engineering related to light-water reactor nuclear power plants. The period between the Fifth International Conference on Structural Mechanics for Reactor Technology, held in Berlin in 1979, and the 1981 Sixth Conference in Paris is discussed. A listing of research projects recently completed and the status of research presently under way are included.