Internal cathodic protection to study the erosion-corrosion of AISI 1018 carbon steel

Steel elbows used in pipelines carrying potash slurry may undergo material loss due to mechanical erosion and/or electrochemical corrosion. Cathodic protection was used to study the effects of flow velocity and slurry concentration on the protection current density required to maintain AISI 1018 carbon steel elbows at a set electric potential. A flow loop with a peristaltic pump was used to pump a slurry consisting of silica sand in a saturated potash brine through the steel elbows. The protection current density measurements were performed under varying slurry flow velocities of 2.5, 3.0, 3.5, and 4.0 m/s and varying slurry concentrations ranging from 0-35 wt%. The results show maximum values of protection current density were required for mid-range slurry concentrations. It is concluded that, within the parameters of study, high flow velocities require higher protection current density than low flow velocities. Furthermore, high flow velocities result in a local maximum protection current density being reached at lower slurry concentrations; conversely, a local maximum protection current density is reached at higher slurry concentrations in lower flow velocities. The contrast in local maximum protection current densities likely occurs due to additional particle-particle collisions at higher velocities causing the maximum mass transfer rate of oxygen to be reached at lower slurry concentrations. SEM micrographs show that wear becomes more evenly distributed with increasing flow velocity due to the homogeneous distribution of particles in the flowing medium.     

Extrusion of polypropylene/chitosan/poly(lactic-acid) films: Chemical,mechanical, and thermal properties

Development of extruded films composed of biopolymers blended with synthetic polymers aims to minimize the environmental impact of plastic waste-materials and lead to the sustainable plastic industry. To produce biodegradable polymeric blends, the weight content of biopolymers must be maximum without compromising the performance properties of the extruded films. Using a solvent-free extrusion method, films composed of polypropylene, poly(lactic-acid), and Chitosan, can be obtained with the use of polypropylene-graft-maleic anhydride and glycerol as compatibilizer and plasticizer, respectively. Extruded films with up to a 50 wt% content of biopolymers show acceptable thermal and mechanical properties, where the use of compatibilizer improves the processing characteristics and homogeneous distribution of chitosan throughout the films. Therefore, the extruded films can be considered as alternatives to conventional synthetic-polymer films, due to their acceptable mechanical and thermal properties with direct potential applications in extrusion-method mass production of biodegradable polymers.     

Student perception on the impact of the Livescribe smartpen as an accommodation

Universal Access in the Information Society - The goal of this exploratory qualitative study was to determine how students with disabilities in higher education are using the Livescribe smartpen in...     

Spatial location is critical for conditioning place preference with visual but not tactile stimuli.

The roles of visual, tactile, and spatial location cues were studied in 6 conditioned place preference (CPP) experiments with ethanol (2 g/kg) in mice (of the DBA/2J strain). Visual cues were effective conditioned stimuli (CSs) when consistently presented in the same spatial location, but not when the same cue was presented in two different locations during training. In contrast, tactile CSs were effective regardless of spatial location during training. Moreover, spatial location controlled CPP expression when visual cues were used but not when tactile cues were used. However, spatial location per se was not an effective CS. These studies suggest that CPP conditioned to tactile cues is mediated by brain systems different from those mediating CPP conditioned to visual-spatial cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A debugger for parallel processes

A system for analysing and debugging parallel Fortran codes is in use on the Sun workstation. The system is composed of a parallel processing simulator mtsim, a window- and mouse-based debugging tool mtdbx, and a set of real-time display routines. The simulator mtsim, which is called from Fortran by a set of routines having the same syntax as the CRAY X-MP multitasking library, causes several concurrently active user tasks to be executed. The debugger mtdbx is based on the Sun dbxtool debugging facility. It has an enhanced command interface with functional control of parallel processes in multiple windows. The display routines offer two real-time views of multitasking synchronization primitives as they are used during execution. These three components of the debugging system afford the opportunity to analyse the behaviour of parallel processes by dynamic interaction at run-time.     

Attributional style, depression, and perceptions of consensus for events.

This study examined the differences between depressed and nondepressed individuals' implicit perceptions of consensus, which may contribute to differences in their attributional styles. Subjects rated the extent to which positive, negative, and neutral events happen to themselves and to the average college student and completed measures of depth of depression and attributional style. Perceptions of consensus were highly correlated with all components of attributional style for negative and positive events. Hierarchical regression analyses revealed that ratings of others explained variance in attributional style beyond that explained by ratings of the self for positive but not for negative events. Path analyses, however, indicated that the indirect path from perceptions of consensus to depression mediated through attributional style was nonsignificant for positive events, although it was significant for negative events. These findings are discussed in terms of the role of perceptions of others as precursors of attributional style and depression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of reciprocal peer tutoring on mathematics and school adjustment: A component analysis.

Examined the relative impact of structured peer tutoring and group reward components of the reciprocal peer-tutoring intervention on the mathematics performance of elementary school students at high risk for academic failure. 64 students were selected randomly from a pool of 80 4th- and 5th-grade students. Students were assigned randomly to 4 conditions: structure plus reward; reward only; structure only; and no structure, no reward. Findings indicate that students who received both components showed the highest levels of accurate math computations. Analyses of collateral measures revealed that students in the group-reward conditions received higher classroom conduct reports than students in the nonreward conditions. Students in the structured conditions reported higher levels of scholastic competency and self-control than did students in the nonstructured conditions. Data were reported on treatment integrity and teacher and student satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simulation and Fabrication of Stronger,Larger, and Faster Walking Biohybrid Machines

Advancing biologically driven soft robotics and actuators will involve employing different scaffold geometries and cellular constructs to enable a controllable emergence for increased production of force. By using hydrogel scaffolds and muscle tissue, soft biological robotic actuators that are capable of motility have been successfully engineered with varying morphologies. Having the flexibility of altering geometry while ensuring tissue viability can enable advancing functional output from these machines through the implementation of new construction concepts and fabrication approaches. This study reports a forward engineering approach to computationally design the next generation of biological machines via direct numerical simulations. This was subsequently followed by fabrication and characterization of high force producing biological machines. These biological machines show millinewton forces capable of driving locomotion at speeds above 0.5 mm s^?1. It is important to note that these results are predicted by computational simulations, ultimately showing excellent agreement of the predictive models and experimental results, further providing the ability to forward design future generations of these biological machines. This study aims to develop the building blocks and modular technologies capable of scaling force and complexity of these devices for applications toward solving real world problems in medicine, environment, and manufacturing.