Preparation and characterization of biocompatible carbon electrodes

Electron transfer in microbial fuel cell and biosensors could be facilitated through high conductive materials with enhanced active surface area and appropriate redox potential suited to microbial metabolism. In the first strategy based on bulk doping, graphite/epoxy composite electrode (GECE) bulk was modified with six types of metal ion which were prepared through a wet impregnation procedure. In the second strategy, immobilization of redox dye on carbon cloth and graphite sheet was carried out using N,N′-dicyclohexylcarbodiimide for surface modification. Crystallinity, morphology, surface chemistry and electrochemical properties of all modified electrodes were investigated. Influence of redox behavior of electrodes suited to microbial metabolism and conducive to biofilm formation have been examined. It was observed that the Fe³⁺ doped GECE surfaces exhibited significantly high biofilm formation of 1.10(±0.18) × 10⁷ CFU/cm² as compared to other dopants. The microbial growth on the carbon cloth electrode and carbon fiber reinforced plate were found to be less (2.6(±0.97) × 10⁴, 4.8(±1.8) × 10³ CFU/cm² respectively) compared to GECEs.     

Steel Hexagonal Honeycomb Core Equivalent Elastic Moduli for Bridge Deck Sandwich Panels

Glass fiber-reinforced polymer (GFRP) materials possess inherently high strength-to-weight ratios, but their effective elastic moduli are low relative to civil engineering (CE) construction materials. While elastic modulus may be comparable to that of some CE materials, the lower shear modulus adversely affects stiffness. As a result, serviceability issues are what govern GFRP deck design in the CE bridge industry. An innovative solution to increase the stiffness of a commercial GFRP reinforced-sinusoidal honeycomb sandwich panel was proposed; this solution would completely replace the GFRP honeycomb core with a hexagonal honeycomb core constructed from commercial steel roof decking. The purpose of this study was to perform small-scale tests to characterize the steel hexagonal honeycomb core equivalent elastic moduli in an effort to simplify the modeling of the core. The steel core equivalent moduli experimental results were compared with theoretical hexagonal honeycomb elastic modulus equations from the literature, demonstrating the applicability of the theoretical equations to the steel honeycomb core. Core equivalent elastic modulus equations were then proposed to model and characterize the steel hexagonal honeycomb as applicable to sandwich panel design. The equivalent honeycomb core will enable an efficient sandwich panel stiffness design technique, both for structural analysis methods (i.e., hand calculations) and finite-element analysis procedures.     

Leadership perceptions as a function of race–occupation fit: The case of Asian Americans.

On the basis of the connectionist model of leadership, we examined perceptions of leadership as a function of the contextual factors of race (Asian American, Caucasian American) and occupation (engineering, sales) in 3 experiments (1 student sample and 2 industry samples). Race and occupation exhibited differential effects for within- and between-race comparisons. With regard to within-race comparisons, leadership perceptions of Asian Americans were higher when race–occupation was a good fit (engineer position) than when race–occupation was a poor fit (sales position) for the two industry samples. With regard to between-race comparisons, leadership perceptions of Asian Americans were low relative to those of Caucasian Americans. Additionally, when race–occupation was a good fit for Asian Americans, such individuals were evaluated higher on perceptions of technical competence than were Caucasian Americans, whereas they were evaluated lower when race–occupation was a poor fit. Furthermore, our results demonstrated that race affects leadership perceptions through the activation of prototypic leadership attributes (i.e., implicit leadership theories). Implications for the findings are discussed in terms of the connectionist model of leadership and leadership opportunities for Asian Americans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do trajectories of household risk in childhood moderate pubertal timing effects on substance initiation in middle school?

Previous research on pubertal timing has either evaluated contextual predictors of early puberty or negative adjustment outcomes associated with off-time development, especially early maturation. In this study, we integrated these 2 lines of research by evaluating the moderating influence of early childhood household risk on associations between early puberty and 8th-grade substance use in a longitudinal sample of 1,070 participants. We determined trajectories of early childhood household risk using group-based trajectory analysis. Rates of early maturation were higher but not significantly so in groups with high household risk. Early timing was associated with higher rates of substance initiation only among individuals with a history of high household risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining the neural correlates of choice behavior in a gambling task using steady state topography.

The present study investigated the behavioral and neuropsychological characteristics of decision-making behavior during a gambling task as well as how these characteristics may relate to the Somatic Marker Hypothesis and the Frequency of Gain model. The applicability to intertemporal choice was also discussed. Patterns of card selection during a computerized interpretation of the Iowa Gambling Task were assessed for 10 men and 10 women. Steady State Topography was employed to assess cortical processing throughout this task. Results supported the hypothesis that patterns of card selection were in line with both theories. As hypothesized, these 2 patterns of card selection were also associated with distinct patterns of cortical activity, suggesting that intertemporal choice may involve the recruitment of right dorsolateral prefrontal cortex for somatic labeling, left fusiform gyrus for object representations, and the left dorsolateral prefrontal cortex for an analysis of the associated frequency of gain or loss. It is suggested that processes contributing to intertemporal choice may include inhibition of negatively valenced options, guiding decisions away from those options, as well as computations favoring frequently rewarded options. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An approach to setting ecological flow thresholds for southern English chalk streams

This paper presents a study of 10 English chalk streams in the River Thames Basin historically affected by abstraction of groundwater. Using macroinvertebrates, macrophytes and river discharge records from across 76 monitoring sites, and spanning the period 1992–2009 we assess how the communities change over time. River discharge is seen to be the most influential variable in biological community composition, and is used to calculate the annual average river discharge (in m³/s) needed to sustain different biological assemblages at each study site, from the lowest to the highest expression of fluvial aquatic community development. This represents a bottom‐up or site‐specific approach to the determination of ecological flow thresholds, from which more empirical trends may be inferred at regional level. The approach also provides a useful understanding of the timescales involved in the recovery of communities from drought.     

Continuance in online participation following the compromise of older adults’ identity information: a literature review

ABSTRACT

This paper presents findings from a literature review on older adults continued use of the Internet following an identity theft incident. Globally, identity theft is increasing, statistics show that the number of older adults falling victim to identity theft is growing. Victims of identity theft suffer emotional, physical, psychological, and social problems; many change their behaviour as a result. The aim of the review was to examine literature to determine what is known regarding how older adults use the Internet and/or modify their online behaviour following an identity theft event. It was found that knowledge is lacking regarding the impact that identity theft events have on older adults’ continuation of Internet use. Little research has been undertaken to understand the factors and interrelationships that contribute to the situation. The review highlights that a systems ergonomics approach should be considered as an appropriate framework to drive future research in this area.     

Coal-tar-based pavement sealcoat and PAHs: implications for the environment, human health, and stormwater management

Coal-tar-based sealcoat products, widely used in the central and eastern U.S. on parking lots, driveways, and even playgrounds, are typically 20-35% coal-tar pitch, a known human carcinogen that contains about 200 polycyclic aromatic hydrocarbon (PAH) compounds. Research continues to identify environmental compartments-including stormwater runoff, lake sediment, soil, house dust, and most recently, air-contaminated by PAHs from coal-tar-based sealcoat and to demonstrate potential risks to biological communities and human health. In many cases, the levels of contamination associated with sealed pavement are striking relative to levels near unsealed pavement: PAH concentrations in air over pavement with freshly applied coal-tar-based sealcoat, for example, were hundreds to thousands of times higher than those in air over unsealed pavement. Even a small amount of sealcoated pavement can be the dominant source of PAHs to sediment in stormwater-retention ponds; proper disposal of such PAH-contaminated sediment can be extremely costly. Several local governments, the District of Columbia, and the State of Washington have banned use of these products, and several national and regional hardware and home-improvement retailers have voluntarily ceased selling them.