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1.
Heidi Bernas Arie J. Plomp Johannes H. Bitter Dmitry Yu. Murzin 《Catalysis Letters》2008,120(1-2):8-13
The density functional theory (DFT/B3LYP) calculations were applied to investigate the interaction of a Pt6 particle with the ZSM-5 zeolite framework. The electronic structure of the metal particle is strongly affected by the interaction with basic framework oxygens and acid sites of the zeolite support. Adsorption on basic sites (Eads = 6 kcal/mol) favors the formation of the electron enriched metal cluster. Interaction of the platinum cluster with the acid site characterized by stabilization energy of 47 kcal/mol results in oxidation of the metal particle and suppression of Brønsted acidity of the support. The hypothesis is put forward that the oxidized platinum particle can function as an active site for the alkane isomerisation on platinum supported high silica zeolites. 相似文献
2.
The Humanitarian Engineering initiative, sponsored by the William and Flora Hewlett Foundation, at the Colorado School of Mines, is creating a program that will support engineering students in understanding their responsibility for solving community development problems that exist throughout the world. As part of this effort, data has been collected on faculty and student attitudes using the ‘Community Service Attitudes Scale,” developed and validated by Shiarella, McCarthy, and Tucker. During the fall 2004, 78 students and 34 faculty members responded to this instrument. Statistically significant differences were found between the attitudes of students and faculty, males and females, and among different age groupings with respect to service activities. A general finding was that faculty displayed better attitudes toward community service than the students. 相似文献
3.
Chronis Andrea M.; Lahey Benjamin B.; Pelham William E. Jr.; Williams Stephanie Hall; Baumann Barbara L.; Kipp Heidi; Jones Heather A.; Rathouz Paul J. 《Canadian Metallurgical Quarterly》2007,43(1):70
Children with attention-deficit/hyperactivity disorder (ADHD) are at risk for adverse outcomes such as substance abuse and criminality, particularly if they develop conduct problems. Little is known about early predictors of the developmental course of conduct problems among children with ADHD, however. Parental psychopathology and parenting were assessed in 108 children who first met Diagnostic and Statistical Manual of Mental Disorders (4th ed.) criteria for ADHD at 4-7 years old. When demographic variables and baseline ADHD and conduct problems were controlled, maternal depression predicted conduct problems 2-8 years following the initial assessment, whereas positive parenting during the structured parent- child interaction task predicted fewer future conduct problems. These findings suggest that maternal depression is a risk factor, whereas early positive parenting is a protective factor, for the developmental course of conduct problems among children with ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Polymer blends consisting of linear poly(l-lactide) (PLLA) and different proportions of dendritic PLLA-based copolyesters (hb-PLLA) characterized by different degrees of branching (DB) were obtained in melt. The solid-state properties of poly(l-lactide)s and their blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), atomic force microscopy (AFM) and stress-strain measurements. DSC and DMA methods proved miscibility of PLLA/hb-PLLA blends for the studied composition range. AFM indicated that no phase separation occurs in PLLA/hb-PLLA blends and that PLLA and hb-PLLA cocrystallize in one single lamellae type. The mechanical characteristics of PLLA/hb-PLLA blends deteriorated with an increase of the DB and with changing blend composition. Susceptibility of the blends to biodegradation was studied by measuring the weight loss in two different biodegradation media. PLLA/hb-PLLA blends showed more pronounced hydrophilic character and higher susceptibility to biodegradation with an increase in the degree of branching. 相似文献
5.
The US workforce is aging. At the same time, there are a record number of open positions in the transportation sector, which has traditionally been a well-paying, but stressful and schedule-dependent, occupation. Due to increasing longevity, need, and ability to work, a possible solution to the transportation workforce shortfall may lie within the retention and recruitment of older workers. This paper uses a socio-technical framework to examine the pertinent, though scant, literature and data related to older workforce demographics and operational needs, the regulatory environment, requisite knowledge, skills and abilities, and application of support technology and training. Although there is evidence of age-related changes in physiology and cognition, the current science remains unable to resolve how an older workforce may most appropriately be applied to transportation to maximize system safety and minimize negative impact to worker well-being. 相似文献
6.
Kirsten Berthold Heidi RöderDaniel Knörzer Wolfgang KesslerAlexander Renkl 《Computers in human behavior》2011,27(1):69-75
Explanation prompts usually foster conceptual understanding. However, it has been claimed within cognitive load theory that prompts can take cognitive load to the upper limit when learning complex contents. Under such circumstances, prompts focusing the learners’ attention on specific aspects (e.g., conceptual aspects such as elaborations on domain principles) might have some costs: Other important aspects (e.g., procedural aspects such as how to calculate) cannot be processed deeply. Thus, we expected that conceptually-oriented explanation prompts would foster the detailedness of explanations, the number of elaborations on domain principles, and conceptual knowledge. In addition, we tested the influence of such prompts on the number of calculations performed during learning and procedural knowledge. We conducted an experiment in which we employed conceptually-oriented explanation prompts in a complex e-learning module on tax law. Tax law university students (N = 40) worked on this e-learning module under two conditions: (a) conceptually-oriented explanation prompts, (b) no prompts. The prompts led to double-edged effects: positive effects on the detailedness of explanations and on the number of elaborations on domain principles, as well as on conceptual knowledge and simultaneously negative effects on the number of calculations performed during learning as well as on procedural knowledge. 相似文献
7.
Lam H 《IEEE transactions on visualization and computer graphics》2008,14(6):1149-1156
Interaction cost is an important but poorly understood factor in visualization design. We propose a framework of interaction costs inspired by Norman’s Seven Stages of Action to facilitate study. From 484 papers, we collected 61 interaction-related usability problems reported in 32 user studies and placed them into our framework of seven costs: (1) Decision costs to form goals; (2) System-power costs to form system operations; (3) Multiple input mode costs to form physical sequences; (4) Physical-motion costs to execute sequences; (5) Visual-cluttering costs to perceive state; (6) View-change costs to interpret perception; (7) State-change costs to evaluate interpretation. We also suggested ways to narrow the gulfs of execution (2–4) and evaluation (5–7) based on collected reports. Our framework suggests a need to consider decision costs (1) as the gulf of goal formation. 相似文献
8.
This article provides an overview of the factors that may contribute to the effective term of protection for a pharmaceutical product in the USA––by patent and by FDA market exclusivities, identifies public and commercial sources for collecting relevant patent term and exclusivity data, and provides a strategy for ensuring that the effective term of protection has been calculated accurately. 相似文献
9.
Heidi A. McKee Author Vitae 《Computers and Composition》2004,21(3):315-340
In this article, I examine an asynchronous online discussion about sexuality that lasted for several weeks and involved students at three different universities, seven of whom I interviewed. Although issues of gay rights and alliance groups were brought up, students focused primarily on the causes of homosexuality and whether homosexuality is natural or not, with one student insistently posting that homosexuality is unnatural because same-sex couples cannot experience “true love-making.” On one level the focus on the causes and naturalness of homosexuality (with few references to heterosexuality) reinforced the heteronormative binaries that often structure thinking and discussions about sexuality, a reinforcement that I initially found disheartening. However, in many ways I came to realize that this online thread still served important academic and personal purposes for students despite and because of being situated in binaries. Drawing from my reading of the posts and from discourse-based interviews with participants, I show that online discussions developed around heteronormative binaries can serve as catalysts for movement in students’ thinking about complex issues and that online spaces in particular are valuable forums for students to articulate and then complicate their understandings of issues relating to sexuality and sexual orientation. 相似文献
10.
(续接本刊2007年第7期第36页)2电子废物管理方式和立法提案2.1延伸生产者责任制延伸生产者责任制(EPR)作为废物管理的新模式得以广泛推广。OECD将EPR定义为一种新的环境制度,在该制度下,生产者对其产品的责任延伸到产品销售后的整个生命周期,包括最终处置(OECD,2001)。与污染者付费原则一致, 相似文献