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11.
Jing‐Qi Chi Xiao‐Jun Zeng Xiao Shang Bin Dong Yong‐Ming Chai Chen‐Guang Liu Melinda Marin Yadong Yin 《Advanced functional materials》2019,29(33)
Rational design and controllable synthesis of well‐defined nanostructures with high stability and Pt‐like activity for hydrogen evolution reaction (HER) are critical for renewable energy conversion. Herein, a unique pyrolysis strategy is demonstrated for the synthesis of RhPx nanoparticles (NPs) in N, P co‐doped thin carbon nanoshells (RhPx@NPC nanoshells) that display high electrocatalytic activity and stability over a wide pH range. This strategy involves simultaneous phosphorization and pyrolysis processes that can produce highly‐dispersed RhPx NPs within N, P co‐doped carbon nanoshells and at the same time induce thinning of carbon nanoshells from inside out. The resulting RhPx@NPC nanoshells not only possess Pt‐like activity for HER with low overpotentials to achieve 10 mA cm?2 (22 mV in 0.5 m H2SO4, 69 mV in 1.0 m KOH, and 38 mV in 1.0 m phosphate buffered saline (PBS)) but also provide long‐term durability in a wide pH range. The remarkable HER performance of RhPx@NPC nanoshells is ascribed to the high surface area, abundant mesoporosity, strong catalyst–support interaction, ultrathin carbon encapsulation, and N, P co‐doping. This work provides an effective strategy for designing heterostructured electrocatalysts with high catalytic activity and stability desired for reactions that may occur under harsh conditions. 相似文献
12.
The factors leading to the continuing problems with information system (IS) project failure are of importance to both the research and practitioner communities. The psychological factors that lead project managers to escalate troubled projects are investigated. Theoretical grounding is presented for a research model consisting of Need for Achievement as an antecedent trait for implementation mindset, internal locus of control, preference for consistency, and time urgency, which in turn predict the Intention to Continue a troubled IS project. Using responses from 232 IS project stakeholders, the model is tested using structural equation modeling. The results support Need for Achievement as an antecedent to the other independent variables. Implementation mindset and internal locus of control were found to be significant predictors of the project managers’ intention to continue the IS projects. Based on the findings, suggestions for project re-evaluation milestones (PRMs) are presented. 相似文献
13.
Nancy A. Skopp Derek J. Smolenski Melinda J. Metzger-Abamukong Albert A. Rizzo Greg M. Reger 《International journal of human-computer interaction》2014,30(1):24-31
This pilot study assessed the utility and acceptability of the VirtuSphere, a cutting edge navigation platform designed to enhance presence in virtual environments. The VirtuSphere includes a 12-ft hollow sphere within which the user stands, and it rolls within a wheeled platform, in any direction, according to the user's steps. The pilot was a within-subject crossover design comparing the VirtuSphere to standard game controller navigation. The comparison was based on locomotion in Virtual Iraq, a virtual world resembling Iraqi war zones. Participants were 10 active duty soldiers not suffering from posttraumatic stress disorder. Results indicated that there were negligible differences in sense of presence, simulator sickness, and satisfaction across the two navigation systems. Although the VirtuSphere may provide entertainment value, these results do not provide initial support for the use of the VirtuSphere to improve constructs thought to be important to behavioral health applications of virtual reality. Potential improvements to the design of the VirtuSphere are discussed. 相似文献
14.
Investment in information technology is steadily increasing, but many organizations find it difficult to formally assess the value of IT investments because the latter are often incorporated into broad management initiatives. the authors believe that the results of the research study reported on here can help firms to develop a better understanding of the dynamic relationship between IT investment and performance at both the firm and industry levels of analysis. This study clearly demonstrates the importance of adopting an organizational change perspective when assessing the impact of IT investment on firm performance. 相似文献
15.
Melinda Földvári 《The Visual computer》1995,11(4):218-226
Equihue color scales are among the simplest types of color harmonies. They are particularly suited to teach and study theories of harmony. Ordered color scales allow color coding and scientific visualization. Here we describe a teaching program that supports the study of equihue harmony. Methods for the generation of harmonies are presented, and the resulting aesthetic impressions are discussed. 相似文献
16.
Human sewage contamination of surface waters is a major human health concern. We found urban stormwater systems that collect and convey runoff from impervious surfaces act as a conduit for sewage originating from breeches in sanitary sewer infrastructure. A total of 828 samples at 45 stormwater outfalls were collected over a four-year period and assessed by culture based methods, PCR, and quantitative PCR (qPCR) to test for traditional and alternative indicators of fecal pollution. All outfalls had the HF183 (human) Bacteroides genetic marker detected in at least one sample, suggesting sewage contamination is nearly ubiquitous in the urban environment. However, most outfalls were intermittently positive, ranging from detection in 11%-100% of the samples. Positive results did not correlate with seasonality, rainfall amounts, or days since previous rainfall. Approximately two-thirds of the outfalls had high (>5000 copy number, i.e. CN, per 100 ml) or moderate levels (1000-5000 CN per 100 ml) of the human Bacteroides genetic marker. Escherichia coli (E. coli) and enterococci levels did not correlate to human Bacteroides. A total of 66% of all outfall samples had standard fecal indicator levels above 10,000 CFU per 100 ml. A tiered assessment using this benchmark to identify high priority sites would have failed to flag 35% of the samples that had evidence of sewage contamination. In addition, high fecal indicators would have flagged 33% of samples as priority that had low or no evidence of sewage. Enteric virus levels in one outfall with high levels of the human Bacteroides genetic marker were similar to untreated wastewater, which illustrates stormwater can serve as a pathway for pathogen contamination. The major source of fecal pollution at four of five river sites that receive stormwater discharge appeared to be from sewage sources rather than non-human sources based on the ratios of human Bacteroides to total Bacteroides spp. This study shows the feasibility and benefits of employing molecular methods to test for alternative indicators of fecal pollution to identify sewage sources and potential health risks and for prioritization of remediation efforts. 相似文献
17.
Previous research demonstrated that 12 mo of total social isolation initiated at birth produced severe and seemingly permanent social deficits in rhesus monkeys. Such monkeys exhibited self-clasping, self-mouthing, and other stereotypic, self-directed responses. Recent research has indicated that 6-mo-isolated monkeys could develop social behaviors if exposed to younger, socially unsophisticated "therapist" monkeys. In the present experiment, 4 12-mo isolate-reared monkeys developed appropriate species-typical behavior through the use of adaptation, self-pacing of visual input, and exposure to 4 younger "therapist" monkeys. Adaptation enabled the isolate Ss to become familiar with their postisolation environment, while self-pacing facilitated their watching the therapist Ss' social interactions. The isolates showed a marked decrease in self-directed behaviors following extensive intimate contact with the therapists. Species-typical behaviors significantly increased during this period, so that the isolate behavioral repertoire did not differ substantially from the therapist behavioral repertoire by the end of the therapy period. Results clearly fail to support a critical period for socialization in the rhesus monkey, and an alternative environment-specific learning hypothesis is proposed. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
18.
We tested the hypothesis that poor performance on the Piagetian invisible displacement task is related to increased memory requirements. Rhesus monkeys and orangutans received 3 types of problems (invisible, visible, and no transfer problems) each containing a number of steps equivalent to that of standard invisible displacements. If failure to solve invisible displacements was due to increased memory requirements, then the primates should perform at chance level on all 3 problems. However, rhesus monkeys solved visible and no transfer problems, but not invisible transfer problems. Half of the orangutans solved all 3 transfer problems, although their performance on invisible transfer problems was lower than that on the other problems. A subsequent cuing phase led to improved performance, and a few monkeys solved invisible transfer problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
Specific sleepiness symptoms are indicators of performance impairment during sleep deprivation 总被引:1,自引:0,他引:1
Mark E. Howard Melinda L. Jackson David Berlowitz Fergal O’Donoghue Philip Swann Justine Westlake Vanessa Wilkinson Rob J. Pierce 《Accident; analysis and prevention》2014
Drivers are not always aware that they are becoming impaired as a result of sleepiness. Using specific symptoms of sleepiness might assist with recognition of drowsiness related impairment and help drivers judge whether they are safe to drive a vehicle, however this has not been evaluated. In this study, 20 healthy volunteer professional drivers completed two randomized sessions in the laboratory – one under 24 h of acute sleep deprivation, and one with alcohol. The Psychomotor Vigilance Task (PVT) and a 30 min simulated driving task (AusEdTM) were performed every 3–4 h in the sleep deprivation session, and at a BAC of 0.00% and 0.05% in the alcohol session, while electroencephalography (EEG) and eye movements were recorded. After each test session, drivers completed the Karolinska Sleepiness Scale (KSS) and the Sleepiness Symptoms Questionnaire (SSQ), which includes eight specific sleepiness and driving performance symptoms. A second baseline session was completed on a separate day by the professional drivers and in an additional 20 non-professional drivers for test–retest reliability. There was moderate test–retest agreement on the SSQ (r = 0.59). Significant correlations were identified between individual sleepiness symptoms and the KSS score (r values 0.50–0.74, p < 0.01 for all symptoms). The frequency of all SSQ items increased during sleep deprivation (χ2 values of 28.4–80.2, p < 0.01 for all symptoms) and symptoms were related to increased subjective sleepiness and performance deterioration. The symptoms “struggling to keep your eyes open”, “difficulty maintaining correct speed”, “reactions were slow” and “head dropping down” were most closely related to increased alpha and theta activity on EEG (r values 0.49–0.59, p < 0.001) and “nodding off to sleep” and “struggling to keep your eyes open” were related to slow eye movements (r values 0.67 and 0.64, p < 0.001). Symptoms related to visual disturbance and impaired driving performance were most accurate at detecting severely impaired driving performance (AUC on ROC curve of 0.86–0.91 for detecting change in lateral lane position greater than the change at a BAC of 0.05%). Individual sleepiness symptoms are related to impairment during acute sleep deprivation and might be able to assist drivers in recognizing their own sleepiness and ability to drive safely. 相似文献
20.
Shear induced deformation and rupture of two types of droplets, hydroxypropyl methylcellulose (HPMC) aqueous solution and modified waxy maize suspension, were studied and compared using a counter-rotating rheo-optical set-up. The motivation of the work was to explain the difference observed in flavour perception of food products thickened by these two fluids. A droplet of either fluid was placed into silicon oil and deformation and break-up were monitored as a function of applied shear stress and strain. It was found that starch suspension droplets broke up at lower deformation stress and strain than HPMC solution droplets despite viscosity ratio and capillary number suggesting the opposite. It is hypothesised that the ease with which droplets thickened by starch break-up is responsible for their rapid mixing with saliva. 相似文献