1,945 research outputs found
Bridging The Materials Gap In Catalysis: Reactivity Studies Of Nanostructured Titania
ABSTRACT
BRIDGING THE MATERIALS GAP IN CATALYSIS:
REACTIVITY STUDIES OF NANOSTRUCTURED TITANIA
David A. Bennett
John M. Vohs
Surface science studies of defect-free, single-crystal model catalysts have provided vital knowledge in the form of structure-activity relationships and elementary reaction mechanisms. However, there is some difficultly in extending this understanding to more complex systems, since these model catalysts typically lack the range of features that occur on the high surface area catalysts used in industry. This project seeks to bridge the gap between these two classes of materials by studying thin films of well-defined TiO2 nanocrystals with tunable size and morphology using traditional surface science techniques. This enables the controlled introduction of features lacking in single-crystal model catalysts, allowing for the formulation of more complex structure-activity relationships. The thermal- and photocatalytic reactions of methanol to produce methane, formaldehyde, dimethyl ether, and methyl formate on these TiO2 nanoparticles were investigated using temperature programmed desorption in ultra high vacuum. Results show clear effects of nanocrystal size and shape on the activity and selectivity of these reactions. This demonstrates the value of studying nanostructured metal-oxide catalysts to better understand the relationship between fundamental catalytic knowledge and the behavior of complex heterogeneous catalysts
Estimating the Required Jacking Force
The process of estimating the required jacking force to jack a pipe through the ground was, and still is, an art requiring much experience and good judgement. Many factors and risks affect the determination of the jacking force. This paper is an attempt to use civil engineering techniques to rationalize and compare methods for estimating the required jacking force. Four of these methods are summarized and used to estimate the jacking loads on a job completed in Staten Island, New York. The actual and predicted results are compared.
The frictional resistance values estimated based on Terzaghi 1 s silo theory with the parameter values selected based on guidance given in the German AWPC manual 11 ATVA 161 11 and in the Kubota are five to seven times higher than the average actual jacking forces. On the other hand, the frictional resistance force calculated by Marston 1 s formula and Terzaghi 1 s coefficient are about twice the average actual jacking force. Therefore, based on this comparison only, multiplying the force calculated by these latter two formulas by an adequate factor of safety would be more appropriate. Terzaghi Is theory with the parameter set of the ATV A 161 and Kubota method are conservative but not the most economical solution. The penetration or tip resistance values estimated using the shear strength resistance method are much lower than those calculated using the passive earth pressure method, which represents the most conservative method
Using mixed methods for analysing culture : The Cultural Capital and Social Exclusion project
This paper discusses the use of material generated in a mixed method investigation into cultural tastes and practices, conducted in Britain from 2003 to 2006, which employed a survey, focus groups and household interviews. The study analysed the patterning of cultural life across a number of fields, enhancing the empirical and methodological template provided by Bourdieuâs Distinction. Here we discuss criticisms of Bourdieu emerging from subsequent studies of class, culture and taste, outline the arguments related to the use of mixed methods and present illustrative results from the analysis of these different types of data. We discuss how the combination of quantitative and qualitative methods informed our analysis of cultural life in contemporary Britain. No single method was able to shed light on all aspects of our inquiry, lending support to the view that mixing methods is the most productive strategy for the investigation of complex social phenomena
In-vivo force, frequency, and velocity of dog gastrointestinal contractile activity
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44364/1/10620_2005_Article_BF02233438.pd
Modification of Expansin Protein Abundance in Tomato Fruit Alters Softening and Cell Wall Polymer Metabolism during Ripening
Exploring the NRO Opportunity for a Hubble-sized Wide-field Near-IR Space Telescope -- NEW WFIRST
We discuss scientific, technical and programmatic issues related to the use
of an NRO 2.4m telescope for the WFIRST initiative of the 2010 Decadal Survey.
We show that this implementation of WFIRST, which we call "NEW WFIRST," would
achieve the goals of the NWNH Decadal Survey for the WFIRST core programs of
Dark Energy and Microlensing Planet Finding, with the crucial benefit of deeper
and/or wider near-IR surveys for GO science and a potentially Hubble-like Guest
Observer program. NEW WFIRST could also include a coronagraphic imager for
direct detection of dust disks and planets around neighboring stars, a
high-priority science and technology precursor for future ambitious programs to
image Earth-like planets around neighboring stars.Comment: 76 pages, 26 figures -- associated with the Princeton "New Telescope
Meeting
Identification of bacteria associated with feline chronic gingivostomatitis using culture-dependent and culture-independent methods
Feline chronic gingivostomatitis (FCGS) is a chronic inflammatory disease of the oral cavity that causes severe pain and distress. There are currently no specific treatment methods available and little is known regarding its aetiology, although bacteria are thought to play a major role. The purpose of this study was to identify the oral bacterial flora in normal and diseased cats. Oral swabs were obtained from the palatoglossal folds of eight cats (three normal and five FCGS) and were subjected to microbiological culture. Pasteurella pneumotropica and Pasteurella multocida subsp. multocida were the most prevalent species identified by culture methods in the normal and FCGS samples, respectively. Bacteria were also identified using culture-independent methods (bacterial 16S rRNA gene sequencing). For the normal samples, 158 clones were analysed and 85 clones were sequenced. Capnocytophaga canimorsus (10.8% of clones analysed) was the predominant species. Uncultured species accounted for 8.2% of clones analysed, and 43.7% of clones analysed represented potentially novel species. For the FCGS samples, 253 clones were analysed and 91 clones were sequenced. The predominant species was P. multocida subsp. multocida (51.8% of clones analysed). Uncultured species accounted for 8.7% of clones analysed, and 4.7% of clones analysed represented potentially novel species. It is concluded that the oral flora in cats with FCGS appears to be less diverse than that found in normal cats. However, P. multocida subsp. multocida is found to be significantly more prevalent in FCGS than in normal cats and consequently may be of aetiological significance in this disease. (C) 2010 Elsevier B.V. All rights reserve
Selective Serotonin Reuptake Inhibitors and Associated Bleeding Risks: A Narrative and Clinical Review.
Major Depressive Disorder (MDD) is a major cause of disability worldwide and is associated with serious lasting impairment. A leading hypothesis of the pathophysiology of MDD is the monoamine deficiency hypothesis which suggests that depression is caused by depletion of serotonin, norepinephrine, or dopamine in the central nervous system. Serotonin is the most widely studied neurotransmitter in the pathophysiology of depression, with studies showing that reduced central serotonin synthesis leads to depressive symptoms in individuals at risk for depression. Selective Serotonin Reuptake Inhibitors (SSRI) inhibit serotonin reuptake and subsequently increase the amount of serotonin available in synapses. Common side effects of SSRIs include increased suicidality of patients under the age of 25, sexual dysfunction, anxiety, dizziness, weight gain, gastrointestinal distress, and headache. Other side effects include prolonging the QT interval, coagulopathy, and the risk of serotonin syndrome, as well as SSRI discontinuation syndrome. Sites of increased bleeding related to SSRI use have been reported to occur in the upper gastrointestinal tract, as well as intracranially. Based on the current literature, three studies have found that SSRIs are not associated with increased bleeding and/or increased perioperative risk, while others have demonstrated that SSRIs are associated with an increased risk in perioperative use. The inhibition of serotonin reuptake can affect platelet aggregation since platelets also express the serotonin transporter. SSRIs can result in decreased storage of serotonin in platelet dense granules. Increased serotonin can also increase gastric acid secretion, which increases the risk for ulceration. SSRIs in combination with NSAIDs also show a significantly increased risk of upper GI bleeding. Some studies show an increased bleeding risk from 30% to 70% when taking a combination of vitamin K antagonists and SSRIs in hospitalized patients. Related to the high prevalence of conditions that are treated with SSRIs, the bleeding risk associated with this class of medication merits further study
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The Role of the Engineered Barrier System in Safety Cases for Geological Radioactive Waste Repoitories: An NEA Initiaive in Co-Operations with the EC, Process Issues and Modeling
The Integration Group for the Safety Case (IGSC) of the Nuclear Energy Agency (NEA) Radioactive Waste Management Committee in co-operation with the European Commission (EC) is conducting a project to develop a greater understanding of how to achieve the necessary integration for successful design, construction, testing, modeling, and assessment of engineered barrier systems. The project also seeks to clarify the role that the EBS plays in assuring the overall safety of a repository. A framework for the EBS Project is provided by a series of workshops that allow discussion of the wide range of activities necessary for the design, assessment and optimization of the EBS, and the integration of this information into the safety case. The topics of this series of workshops have been planned so that the EBS project will work progressively through the main aspects comprising one cycle of the design and optimization process. This paper seeks to communicate key results from the EBS project to a wider audience. The paper focuses on two topics discussed at the workshops: process issues and the role of modeling
Environmentalism, performance and applications: uncertainties and emancipations
This introductory article for a themed edition on environmentalism provides a particular context for those articles that follow, each of which engages with different aspects of environmentalism and performance in community-related settings. Responding to the proposition that there is a lacuna in the field of applied drama and environmentalism (Bottoms, 2010), we suggest that the more significant lack is that of ecocriticism. As the articles in this journal testify, there are many examples of applied theatre practice; what is required is sustained and rigorous critical engagement. It is to the gap of ecocriticism that we address this issue, signalling what we hope is the emergence of a critical field. One response to the multiple challenges of climate change is to more transparently locate the human animal within the environment, as one agent amongst many. Here, we seek to transparently locate the critic, intertwining the personal â ourselves, human actants â with global environmental concerns. This tactic mirrors much contemporary writing on climate change and its education, privileging personal engagement â a shift we interrogate as much as we perform. The key trope we anchor is that of uncertainty: the uncertainties that accompany stepping into a new research environment; the uncertainties arising from multiple relations (human and non-human); the uncertainties of scientific fact; the uncertainties of forecasting the future; and the uncertainties of outcomes â including those of performance practices. Having analysed a particular turn in environmental education (towards social learning) and the failure to successfully combine âart and realityâ in recent UK mainstream theatre events, such uncertainties lead to our suggestion for an âemancipatedâ environmentalism. In support of this proposal, we offer up a reflection on a key weekend of performance practice that brought us to attend to the small â but not insignificant â and to consider first hand the complex relationships between environmental âgrand narrativesâ and personal experiential encounters. Locating ourselves within the field and mapping out some of the many conceptual challenges attached to it serves to introduce the territories which the following journal articles expand upon
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