Showing papers by "University of Delaware published in 2008"
01 Jan 2008
TL;DR: The combination of materials to form a new material system with enhanced material properties is a well documented historical fact as discussed by the authors, which is why many artisans from the Mediterranean and Far East used a form of composite technology in molding art works which were fabricated by layering cut paper in various sizes for producing desired shapes and contours.
Abstract: The combination of materials to form a new material system with enhanced material properties is a well documented historical fact. For example, the ancient Jewish workers during their tenure under the Pharaohs used chopped straws in bricks as a means of enhancing their structural integrity. The Japanese Samurai warriors were known to use laminated metals in the forging of their swords to obtain desirable material properties. Even certain artisans from the Mediterranean and Far East used a form of composite technology in molding art works which were fabricated by layering cut paper in various sizes for producing desired shapes and contours.
3,908 citations
TL;DR: A bioorthogonal reaction that proceeds with unusually fast reaction rates without need for catalysis: the cycloaddition of s-tetrazine and trans-cyclooctene derivatives, which enables protein modification at low concentration.
Abstract: Described is a bioorthogonal reaction that proceeds with unusually fast reaction rates without need for catalysis: the cycloaddition of s-tetrazine and trans-cyclooctene derivatives. The reactions tolerate a broad range of functionality and proceed in high yield in organic solvents, water, cell media, or cell lysate. The rate of the ligation between trans-cyclooctene and 3,6-di-(2-pyridyl)-s-tetrazine is very rapid (k2 2000 M−1 s−1). This fast reactivity enables protein modification at low concentration.
1,257 citations
TL;DR: In this paper, two national energy systems are modelled, one for Denmark, including combined heat and power (CHP) and the other a similarly sized country without CHP (the latter being more typical of other industrialized countries).
983 citations
TL;DR: Automatic event detection from the two kinematic-based algorithms will aid researchers by accurately determining gait events during the analysis of treadmill and overground walking.
922 citations
TL;DR: In this paper, a review of the recent advances in nanotubes and nanotube-based composite sensors and actuators, with a particular emphasis on their electromechanical behavior is presented.
901 citations
TL;DR: In this paper, the tricarboxylic acid cycle intermediate L-malic acid (MA) secreted from roots of Arabidopsis (Arabidopsis thaliana) selectively signals and recruits the beneficial rhizobacterium Bacillus subtilis FB17 in a dose-dependent manner.
Abstract: Beneficial soil bacteria confer immunity against a wide range of foliar diseases by activating plant defenses, thereby reducing a plant's susceptibility to pathogen attack. Although bacterial signals have been identified that activate these plant defenses, plant metabolites that elicit rhizobacterial responses have not been demonstrated. Here, we provide biochemical evidence that the tricarboxylic acid cycle intermediate L-malic acid (MA) secreted from roots of Arabidopsis (Arabidopsis thaliana) selectively signals and recruits the beneficial rhizobacterium Bacillus subtilis FB17 in a dose-dependent manner. Root secretions of L-MA are induced by the foliar pathogen Pseudomonas syringae pv tomato (Pst DC3000) and elevated levels of L-MA promote binding and biofilm formation of FB17 on Arabidopsis roots. The demonstration that roots selectively secrete L-MA and effectively signal beneficial rhizobacteria establishes a regulatory role of root metabolites in recruitment of beneficial microbes, as well as underscores the breadth and sophistication of plant-microbial interactions.
781 citations
TL;DR: The relationship of material damage to material healing is examined in a manner to provide an understanding of the kinetics and damage reversal processes necessary to impart self-healing characteristics.
Abstract: The ability of materials to self-heal from mechanical and thermally induced damage is explored in this paper and has significance in the field of fracture and fatigue. The history and evolution of several self-repair systems is examined including nano-beam healing elements, passive self-healing, autonomic self-healing and ballistic self-repair. Self-healing mechanisms utilized in the design of these unusual materials draw much information from the related field of polymer–polymer interfaces and crack healing. The relationship of material damage to material healing is examined in a manner to provide an understanding of the kinetics and damage reversal processes necessary to impart self-healing characteristics. In self-healing systems, there are transitions from hard-to-soft matter in ballistic impact and solvent bonding and conversely, soft-to-hard matter transitions in high rate yielding materials and shear-thickening fluids. These transitions are examined in terms of a new theory of the glass transition and yielding, viz., the twinkling fractal theory of the hard-to-soft matter transition. Success in the design of self-healing materials has important consequences for material safety, product performance and enhanced fatigue lifetime.
777 citations
TL;DR: This work has established that variations in surface and near-surface atomic structure as a function of size in this smallest of size regimes may make a difference in important geochemical and biogeochemical reactions and kinetics in minerals.
Abstract: Minerals are more complex than previously thought because of the discovery that their chemical properties vary as a function of particle size when smaller, in at least one dimension, than a few nanometers, to perhaps as much as several tens of nanometers. These variations are most likely due, at least in part, to differences in surface and near-surface atomic structure, as well as crystal shape and surface topography as a function of size in this smallest of size regimes. It has now been established that these variations may make a difference in important geochemical and biogeochemical reactions and kinetics. This recognition is broadening and enriching our view of how minerals influence the hydrosphere, pedosphere, biosphere, and atmosphere.
756 citations
TL;DR: The first observation that carbonsupported tungsten carbide (W2C/AC; AC = activated carbon) can effectively catalyze cellulose conversion into polyols is reported, which indicates that the yield of polyols, especially ethylene glycol (EG) and sorbitol, can be significantly increased when the catalyst is promoted with a small amount of nickel.
Abstract: Cellulose, the most abundant source of biomass, is currently regarded as a promising alternative for fossil fuels as it cannot be digested by human beings and thus its use, unlike corn and starch, will not impose a negative impact on food supplies. One of the most attractive routes for the reaction of cellulose utilization is its direct conversion into useful organic compounds. A recent example of the catalytic conversion of cellulose has been demonstrated by Fukuoka and Dhepe, who utilized Pt/Al2O3 as an effective catalyst to convert cellulose into sugar alcohols (Scheme 1, Route A). The product sugar alcohols can be used as chemicals in their own right or as new starting materials for the production of fuels, as demonstrated by Dumesic and co-workers. 6] Recently, Luo et al. have studied this process further. In their work, the reaction was conducted at elevated temperatures so that water could generate H ions to catalyze the hydrolysis reactions. The subsequent hydrogenation reaction was catalyzed by Ru/C. An increased sugar alcohol yield was obtained, which was attributed to the higher reaction temperatures and the wellknown high efficiency of Ru/C in the hydrogenation reaction. . A disadvantage of the above two studies is the use of precious-metal catalysts. The amount of precious metals needed for the degradation of cellulose was relatively high, 4– 10 mg per gram of cellulose. This is too expensive for the conversion of large quantities of cellulose, even though the solid catalyst could be reused. Therefore, it is highly desirable to develop a less expensive but efficient catalyst to replace precious-metal catalysts in this cellulose degradation process. The carbides of Groups 4–6 metals show catalytic performances similar to those of platinum-group metals in a variety of reactions involving hydrogen. In our previous work, tungsten and molybdenum carbides were found to exhibit excellent performances in the catalytic decomposition of hydrazine, which were comparable with those of expensive iridium catalysts. Tungsten carbides have been used as electrocatalysts because of their platinum-like catalytic behavior, stability in acidic solutions, and resistance to CO poisoning. 18] However, to the best of our knowledge, there have been no attempts so far to utilize metal carbides as catalysts for cellulose conversion. Herein we report the first observation that carbonsupported tungsten carbide (W2C/AC; AC = activated carbon) can effectively catalyze cellulose conversion into polyols (Scheme 1, Route B). More interestingly, when the catalyst is promoted with a small amount of nickel, the yield of polyols, especially ethylene glycol (EG) and sorbitol, can be significantly increased. These Ni-W2C/AC catalysts showed a remarkably higher selectivity for EG formation than Pt/Al2O3 [4] and Ru/C. After 30 minutes at 518 K and 6 MPa H2, the cellulose could be completely converted into polyols and the yield of EG was as high as 61 wt % with a 2% Ni-30% W2C/AC-973 catalyst. This value is the highest yield reported to date. Currently in the petrochemical industry, EG is mainly produced from ethylene via the intermediate ethylene oxide. The global production of EG in 2007 is estimated to be 17.8 million tonnes, an increase of Scheme 1. Catalytic conversion of cellulose into polyols.
715 citations
TL;DR: It is a common practice to export instruments developed in one culture to another, and little is known about the consequences of making inappropriate comparisons in cross-cultural research, so several studies were conducted to fill in this gap.
Abstract: It is a common practice to export instruments developed in one culture to another. Little is known about the consequences of making inappropriate comparisons in cross-cultural research. Several studies were conducted to fill in this gap. Study 1 examined the impact of lacking factor loading invariance on regression slope comparisons. When factor loadings of a predictor are higher in the reference group (e.g., United States), for which the scale was developed, than in the focal group (e.g., China), into which the scale was imported, the predictive relationship (e.g., self-esteem predicting life satisfaction) is artificially stronger in the reference group but weaker in the focal group, creating a bogus interaction effect of predictor by group (e.g., self-esteem by culture); the opposite pattern is found when the reference group has higher loadings in an outcome variable. Studies 2 and 3 examined the impact of lacking loading and intercept (i.e., point of origin) invariance on factor means, respectively. When the reference group has higher loadings or intercepts, the mean is overestimated in that group but underestimated in the focal group, resulting in a pseudo group difference.
713 citations
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03 Jan 2008TL;DR: The authors argued that transcranial cognition may be both a logical and a nomological possibility, but no case has been made for its current existence, and they defend a form of contingent intracranialism about the cognitive.
Abstract: Recent work in cognitive science has suggested that there are actual cases in which cognitive processes extend in the physical world beyond the bounds of the brain and the body. We argue that, while transcranial cognition may be both a logical and a nomological possibility, no case has been made for its current existence. In other words, we defend a form of contingent intracranialism about the cognitive.
TL;DR: It is shown that pumpkin plants, grown in an aqueous medium containing magnetite (Fe3O4) nanoparticles, can absorb, translocate, and accumulate the particles in the plant tissues.
Abstract: Rapid development and application of nanomaterials and nanotechnology make assessment of their potential health and environmental impacts on humans, non-human biota, and ecosystems imperative. Here we show that pumpkin plants (Cucurbita maxima), grown in an aqueous medium containing magnetite (Fe3O4) nanoparticles, can absorb, translocate, and accumulate the particles in the plant tissues. These results suggest that plants, as an important component of the environmental and ecological systems, need to be included when evaluating the overall fate, transport and exposure pathways of nanoparticles in the environment.
Book•
01 Jan 2008TL;DR: For the sake of simplicity, we present here only a few different problems of classical mathematical physics which can be treated by boundary integral equations leading to boundary element methods, and in this chapter we consider only two-dimensional problems as mentioned in this paper.
Abstract: For the sake of simplicity, we present here only a few different problems of classical mathematical physics which can be treated by boundary integral equations leading to boundary element methods. Moreover, in this chapter we consider only two-dimensional problems.
01 Jan 2008
TL;DR: In this article, the authors consider how the quality of an infant's attachment to his or her caregiver, subsequent attachment-related experiences, and concurrently assessed states of mind with respect to attachment may be related to risk for psychopathology or to psychological resilience in adulthood.
Abstract: Bowlby (1969/1982, 1973, 1980) proposed a model of development with clearly articulated implications for psychopathology. According to this model, an infant’s formation of an attachment to a caregiver is a key developmental task that influences not only the child’s representations of self and other, but also strategies for processing attachmentrelated thoughts and feelings. Attachment-related events, such as loss and abuse, lead to modifications in these internal representations and affect a child’s strategies for processing thoughts and feelings. Bowlby (1973, 1980) suggested that when children develop negative representations of themselves or others, or when they adopt strategies for processing attachment-related thoughts and feelings that compromise realistic appraisals, they become more vulnerable to psychopathology. In this chapter, we consider how the quality of an infant’s attachment to his or her caregiver, subsequent attachment-related experiences, and concurrently assessed states of mind with respect to attachment (Main & Goldwyn, 1984; Main, Goldwyn, & Hesse, 2003) may be related to risk for psychopathology or to psychological resilience in adulthood.
TL;DR: This study is the first to collect a combination of survey and behavioral data with the cooperation of a major virtual world operator, and the results defy common stereotypes in surprising and interesting ways and have implications for communication theory and for future investigations of games.
Abstract: Online games have exploded in popularity, but for many researchers access to players has been difficult. The study reported here is the first to collect a combination of survey and behavioral data with the cooperation of a major virtual world operator. In the current study, 7,000 players of the massively multiplayer online game (MMO) EverQuest 2 were surveyed about their offline characteristics, their motivations and their physical and mental health. These self-report data were then combined with data on participants’ actual in-game play behaviors, as collected by the game operator. Most of the results defy common stereotypes in surprising and interesting ways and have implications for communication theory and for future investigations of games.
TL;DR: A new ECG enhancement method based on the recently developed empirical mode decomposition (EMD) that is able to remove both high-frequency noise and BW with minimum signal distortion and is validated through experiments on the MIT-BIH databases.
TL;DR: In this paper, a review of the electronic and chemical properties of monolayer bimetallic surfaces (MBSs) is presented, focusing on the general trends in the electronic properties of MBSs.
TL;DR: In this paper, the authors examined how the divergence between insider voting rights and cash-flow rights affects managerial extraction of private benefits of control and found that corporate cash holdings are worth less to outside shareholders, CEOs receive higher levels of compensation, managers are more likely to make shareholdervalue destroying acquisitions, and capital expenditures contribute less to shareholder value.
Abstract: We use a sample of U.S. dual-class companies to examine how the divergence between insider voting rights and cash-flow rights affects managerial extraction of private benefits of control. We find that as the divergence widens at dual-class companies, corporate cash holdings are worth less to outside shareholders, CEOs receive higher levels of compensation, managers are more likely to make shareholder-value destroying acquisitions, and capital expenditures contribute less to shareholder value. These findings support the hypothesis that managers with greater control rights in excess of cash-flow rights are prone to waste corporate resources to pursue private benefits at the expense of shareholders. As such, they contribute to our understanding of why firm value is decreasing in the insider control-cash flow rights divergence.
TL;DR: This paper explores the role of racial bias toward Blacks in interracial relations, and in racial disparities in health care in the United States, and illustrates how this perspective can illuminate and integrate findings from research on disparities and biases in healthCare, addressing the orientations of both providers and patients.
TL;DR: In this article, the authors draw from theories of institutions and collective identities to present a threefold framework of institutional change, involving institutional logics, resources, and social actors, that furthers our understanding of the mitigation of corruption.
Abstract: We draw from theories of institutions and collective identities to present a threefold framework of institutional change—involving institutional logics, resources, and social actors—that furthers our understanding of the mitigation of corruption. Those social actors intent on reforming corruption function as institutional entrepreneurs, and their success depends both on articulating an anticorruption institutional logic that incorporates corruption-disabling identities, cognitive schemas, and practices and on having or developing the resources necessary to propagate the new anticorruption institutional logic.
TL;DR: Findings from a randomized clinical trial that assessed the effectiveness of a relational intervention (Attachment and Biobehavioral Catch-up] with regard to HPA functioning suggest that the ABC intervention is effective in helping children regulate biology in ways more characteristic of children who have not experienced early adversity.
Abstract: Studies with nonhuman primates and rodents, as well as with human children, have suggested that early separations from caregiversare oftenassociated with changesinthe functioning of the hypothalamus–pituitary–adrenal (HPA) axis.On the basis of these findings, we designed a relational intervention that was intended to normalize HPA functioning among children in foster care. This paper presents findings from a randomized clinical trial that assessed the effectiveness of a relational intervention (Attachment and Biobehavioral Catch-up [ABC]) with regard to HPA functioning. The ABC intervention was intended to enhance children’s ability to regulate physiology and behavior. The control intervention (Developmental Education for Families) was intended to enhance children’s cognitive skills. A comparison group of children who had never been in foster care was also included. Children’s cortisol production was assessed upon arrival at the lab, and 15 and 30 min followingthe StrangeSituation. Random effectsanalyses of variancewere performed to assess differencesin initial valuesandchangebetweenchildrenin thetwo interventiongroups.Childreninthe ABCintervention and comparison group children showed lower initial values of cortisol than children in the treatment control group, considering arrival at lab as initial values (p ,.05). Groups did not differ significantly in change over time. These results suggest that the ABC intervention is effective in helping children regulate biology in ways more characteristic of children who have not experienced early adversity.
TL;DR: Problem‐based learning, process‐oriented guided inquiry learning, and peer‐led team learning are student‐centered, active‐learning pedagogies commonly used in science education.
TL;DR: In this paper, the authors summarize relevant academic research findings to contribute to the Public Company Accounting Oversight Board (PCAOB) project on financial statement fraud and to offer insights and conclusions relevant to academics, standard setters, and practitioners.
Abstract: SUMMARY: We summarize relevant academic research findings to contribute to the Public Company Accounting Oversight Board (PCAOB) project on financial statement fraud and to offer insights and conclusions relevant to academics, standard setters, and practitioners. We discuss the characteristics of firms committing financial statement fraud, as identified in the literature, and research related to the fraud triangle. We then discuss research related to the procedures and abilities of auditors to detect fraud, and how fraud risk assessments impact audit planning and testing. In addition, we discuss several “high risk” areas and other issues as identified by the PCAOB. Finally, we summarize prior findings and offer conclusions and suggestions for areas where future research is needed.
TL;DR: The results suggest that females with patellofemoral pain do not employ different mechanics as demand of the activity increases, and seem to demonstrate similar abnormal lower extremity mechanics across a variety of activities.
TL;DR: In this paper, the interlaminar shear strength (ILSS) of traditional glass fiber reinforced epoxy composites enhanced by strategically injecting multi-walled carbon nanotube (MWNT)-epoxy suspensions into stationary glass fiber mats was examined.
Abstract: In this study, we examine the interlaminar shear strength (ILSS) of traditional glass fiber reinforced epoxy composites enhanced by strategically injecting multi-walled carbon nanotube (MWNT)–epoxy suspensions into stationary glass fiber mats. The suspensions were prepared by combining the techniques of high-speed mechanical stirring, ultrasonic agitation and acid oxidation. Two types of process designs were introduced to fabricate the hybrid MWNT/glass/epoxy composites and their relative merits were discussed. Short beam shear (SBS) and compression shear tests (CST) were conducted on the manufactured components to characterize the influence of the process and the weight percentage of nanotubes on the ILSS. The results show that the introduction of MWNT into the composite increased the ILSS by up to 33%. The preferential orientation of the MWNTs in the thickness direction was found to contribute to the increase in the interlaminar shear properties.
TL;DR: A review of permafrost modelling advances can be found in this article, with an emphasis on spatial permafore models, in both arctic and high mountain environments, with an approach to defining the relationship between climate, site surface conditions and permafure status.
Abstract: This paper provides a review of permafrost modelling advances, primarily since the 2003 permafrost conference in Zurich, Switzerland, with an emphasis on spatial permafrost models, in both arctic and high mountain environments. Models are categorised according to temporal, thermal and spatial criteria, and their approach to defining the relationship between climate, site surface conditions and permafrost status. The most significant recent advances include the expanding application of permafrost thermal models within spatial models, application of transient numerical thermal models within spatial models and incorporation of permafrost directly within global circulation model (GCM) land surface schemes. Future challenges for permafrost modelling will include establishing the appropriate level of integration required for accurate simulation of permafrost-climate interaction within GCMs, the integration of environmental change such as treeline migration into permafrost response to climate change projections, and para- meterising the effects of sub-grid scale variability in surface processes and properties on small-scale (large area) spatial models. Copyright # 2008 John Wiley & Sons, Ltd.
TL;DR: This article investigated how different product presentation formats (visual vs. verbal) influence consumer attitudes toward product and purchase intentions in Internet shopping and found that both visual and verbal information had significant effects on affective and cognitive attitudes toward apparel products.
Abstract: The present study investigated how different product presentation formats (visual vs. verbal) influence consumer attitudes toward product and purchase intentions in Internet shopping. The overall results from two Web experiments simulating Internet apparel shopping showed that both visual and verbal information had significant effects on affective and cognitive attitudes toward apparel products, but only verbal information had a significant effect on purchase intention. Though the superiority of visual information was predicted based on prior literature, the results of the study supported verbal superiority. This finding provides an important implication for Internet retailers who tend to pay more attention to visual product presentation. Although visual product presentation is also found to be important, detailed product descriptions are critical to positively influence consumer shopping experience in Internet shopping. © 2008 Wiley Periodicals, Inc.
TL;DR: Using x-ray absorption spectroscopy, it is shown that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS) and is the first to be described in a living system.
Abstract: Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodocarbons in the coastal atmosphere. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic antioxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface and in the apoplast, iodide detoxifies both aqueous oxidants and ozone, the latter resulting in the release of high levels of molecular iodine and the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human blood cells.
TL;DR: This work examines a role of Vps35, an essential retromer subunit, in Wnt signaling in Drosophila and mammalian cells and provides compelling evidence that theretromer complex is required for Wnt secretion.
TL;DR: A quantitative review of studies that measure cultural differences in “cultural products”: tangible, public representations of culture such as advertising or popular texts finds that cultural products that come from Western cultures are more individualistic, and less collectivistic, than cultural products fromCollectivistic cultures.
Abstract: Although cultural psychology is the study of how sociocultural environments and psychological processes coconstruct each other, the field has traditionally emphasized measures of the psychological over the sociocultural. Here, the authors call attention to a growing trend of measuring the sociocultural environment. They present a quantitative review of studies that measure cultural differences in "cultural products": tangible, public representations of culture such as advertising or popular texts. They found that cultural products that come from Western cultures (mostly the United States) are more individualistic, and less collectivistic, than cultural products that come from collectivistic cultures (including Korea, Japan, China, and Mexico). The effect sizes for cultural products were larger than self-report effect sizes for this dimension (reported in Oyserman, Coon, & Kemmelmeier, 2002). In addition to presenting this evidence, the authors highlight the importance of studying the dynamic relationships between sociocultural environments and psyches.