The activity of supported vanadium oxide catalysts for the selective reduction of NO with ammonia

The activities of monolayer V2O5 catalysts for the selective reduction of NO with NH3 are compared with those of commercial available catalysts containing V and/or W. From steady state and pulse experiments it can be concluded that the reduction of surface sites proceeds either by NH3 + NO or by NH3 alone. The reoxidation of the reduced sites occurs by gaseous oxygen or NO. The experimental reaction stoichiometry can be explained in terms of suitable combinations of these four reactions

Revisiting the Tradespace Exploration Paradigm: Structuring the Exploration Process

A number of case applications of tradespace exploration have further extended the types of analyses and knowledge insights that can be gained about tradeoffs between design choices and perceived utility and cost of alternatives. These extensions include application beyond its heritage aerospace domain to the transportation domain, comparing distinct concepts on a common tradespace, considering the impact of changing needs and contexts over time, evaluation of alternatives in a “light effort” manner. In parallel with these case applications, a formalization of the tradespace exploration process has emerged, using a question-driven approach to ensure the knowledge generated is practical and useful to decision makers. These questions are introduced and applied to three example space systems in order to illustrate insights gained in answering the questions. The insights include identifying “good” designs, the strengths and weakness of selected alternatives across a tradespace, limiting constraints and requirements that could allow for less expensive solutions. Additionally, advanced insights include understanding the sensitivities of designs to changes in contexts and needs, and consideration of the differential impact of uncertainty across a set of alternatives with potential opportunities for risk mitigation.Massachusetts Institute of Technology. Engineering Systems Division (Systems Engineering Advancement Research Initiative (SEAri)

Aligning Perspectives and Methods for Value-Driven Design

Recent years have seen a push to use explicit consideration of “value” in order to drive design. This paper conveys the need to explicitly align perspectives on “value” with the method used to quantify “value.” Various concepts of value are introduced in the context of its evolution within economics in order to propose a holistic definition of value. Operationalization of value is discussed, including possible assumption violations in the aerospace domain. A series of prominent Value-Centric Design Methodologies for valuation are introduced, including Net Present Value, Multi-Attribute Utility Theory, and Cost-Benefit Analysis. These methods are compared in terms of the assumptions they make with regard to operationalizing value. It is shown that no method is fully complete in capturing the definition of value, but selecting the most appropriate one involves matching the particular system application being valued with acceptable assumptions for valuation. Two case studies, a telecommunications mission and a deep-space observation mission, are used to illustrate application of the three prior mentioned valuation methods. The results of the studies show that depending on method used for valuation, very different conclusions and insights will be derived, therefore an explicit consideration of the appropriate definition of value is necessary in order to align a chosen method with desired valuation insights.Massachusetts Institute of Technology. Systems Engineering Advancement Research Initiativ

Mechanism of the reaction of nitric oxide, ammonia, and oxygen over vanadia catalysts. I. The role of oxygen studied by way of isotopic transients under dilute conditions

The mechanism of nitric oxide reduction with ammonia to form N2, H2O, and N2O both in the presence and in the absence of O2 over the following series of catalysts, unsupported V2O5, V2O5 on TiO2, V2O5 on SiO2/Al2O3, and V2O5 on Al2O3, has been investigated with the aid of labeled O2 and labeled NH3 at 400°C. The behavior of ammonia was studied both in the presence and in the absence of O2. The presence of labeled O2 gives extra information about the product distribution and the reaction mechanism. Evidence is given that ammonia does not react with O2 or O from any source during the reaction, but that nitrogen and nitrous oxide were produced by a reaction involving all three species, NO, NH3, and/or O2. Nitrous oxide and water are both formed at two different sites of the catalyst. A series of transient tracing studies were performed in a plug-flow reactor using 15NH3 and 18O2. Both 15NN and 15NNO were produced on the unsupported V2O5, V2O5 on TiO2, V2O5 on SiO2/Al2O3, and V2O5 on Al2O3 with very high selectivities. The mechanism of the reaction of NO, NH3, and O2, proposed in a previous paper (ref 2), is further evaluated on the basis of this new experimental evidence

Trends in sexually transmitted infections in general practice 1990-2000: population based study using data from the UK general practice research database

Objective: To describe the contribution of primary care to the diagnosis and management of sexually transmitted infections in the United Kingdom, 1990-2000, in the context of increasing incidence of infections in genitourinary medicine clinics. Design: Population based study. Setting: UK primary care. Participants: Patients registered in the UK general practice research database. Main outcome measures: Incidence of diagnosed sexually transmitted infections in primary care and estimation of the proportion of major such infections diagnosed in primary care. Results: An estimated 23.0% of chlamydia cases in women but only 5.3% in men were diagnosed and treated in primary care during 1998-2000, along with 49.2% cases of non-specific urethritis and urethral discharge in men and 5.7% cases of gonorrhoea in women and 2.9% in men. Rates of diagnosis in primary care rose substantially in the late 1990s. Conclusions: A substantial and increasing number of sexually transmitted infections are diagnosed and treated in primary care in the United Kingdom, with sex ratios differing from those in genitourinary medicine clinics. Large numbers of men are treated in primary care for presumptive sexually transmitted infections

Identification of Small Molecule Inhibitors of the Mitotic Kinase Haspin by High-Throughput Screening Using a Homogeneous Time-Resolved Fluorescence Resonance Energy Transfer Assay

Haspin/Gsg2 is a kinase that phosphorylates histone H3 at Thr-3 (H3T3ph) during mitosis. Its depletion by RNA interference results in failure of chromosome alignment and a block in mitosis. Haspin, therefore, is a novel target for development of antimitotic agents. We report the development of a high-throughput time-resolved fluorescence resonance energy transfer (TR-FRET) kinase assay for haspin. Histone H3 peptide was used as a substrate, and a europium-labeled H3T3ph phosphospecific monoclonal antibody was used to detect phosphorylation. A library of 137632 small molecules was screened at Km concentrations of ATP and peptide to allow identification of diverse inhibitor types. Reconfirmation of hits and IC 50 determinations were carried out with the TR-FRET assay and by a radiometric assay using recombinant histone H3 as the substrate. A preliminary assessment of specificity was made by testing inhibition of 2 unrelated kinases. EC 50 values in cells were determined using a cell-based ELISA of H3T3ph. Five compounds were selected as leads based on potency and chemical structure considerations. These leads form the basis for the development of specific inhibitors of haspin that will have clear utility in basic research and possible use as starting points for development of antimitotic anticancer therapeutic

How to Run the Coupling in the Dipole Approach to the BFKL Equation

We use the dipole expansion to provide a systematic way of including the running coupling into the BFKL equation. In terms of a Borel representation, we obtain an expression for the kernel of the BFKL equation.Comment: 10 pages, latex, 1 figure, included. LaTeX2e compatibility problems fixed: no changes in content

Indications of coherence-incoherence crossover in layered transport

For many layered metals the temperature dependence of the interlayer resistance has a different behavior than the intralayer resistance. In order to better understand interlayer transport we consider a concrete model which exhibits this behavior. A small polaron model is used to illustrate how the interlayer transport is related to the coherence of quasi-particles within the layers. Explicit results are given for the electron spectral function, interlayer optical conductivity and the interlayer magnetoresistance. All these quantities have two contributions: one coherent (dominant at low temperatures) and one incoherent (dominant at high temperatures).Comment: 6 pages, 4 figures, REVTEX

The differential effects of a focus on symptoms versus recovery in reducing stigma of schizophrenia

Although it has been contended that contact with individuals with mental illness is the most effective intervention for stigma reduction, the content of the contact experience is likely to determine whether or not it is beneficial. In the current study, we extend investigations of the impact of whether such contact highlights the potential for recovery versus the nature of acute symptoms. We examine whether any differential impacts persist over a two week period and the extent to which they are mediated by perceptions of similarity and feelings of empathy and/or sympathy. We also measured an overt behaviour, seating distance, at two week follow-up. Using a randomized control design, we found that video exposure to an individual who described his recovery from schizophrenia was generally more effective in improving impressions and reducing preferred level of social distance than when the same person described acute symptoms of schizophrenia or a no-video control condition. These effects persisted up to two weeks. Although the symptom-focused video resulted in great sympathy for the person, this did not translate into positive impressions or reduced social distance. Mediational analyses yielded findings consistent with the benefits of the recovery video being partially mediated by increased perceptions of similarity to the person and lower feelings of sympathy. There were no differential effects of experimental condition on seating distance, but exposure to the recovery-focused video did result in less anxiety in anticipation of meeting the person in the video relative to the control condition

Effects of symptom versus recovery video, similarity, and uncertainty orientation on the stigmatization of schizophrenia

191 participants either watched a video of a person with schizophrenia who discussed his recovery or the symptoms he experienced when acutely ill. Participants were asked to focus either on similarities or differences between themselves and the person depicted. Uncertainty orientation, the extent to which people prefer to resolve uncertainty (uncertainty-orientated) or avoid it in order to main certainty (certainty-orientated) was assessed for each participant. Results showed that for explicit attitudes, the recovery video and uncertainty orientation were significantly associated with more positive responses. The similarity manipulation interacted with video content and uncertainty orientation in influencing implicit attitudes. As expected, compared to those who are uncertainty-oriented, participants who are certainty-oriented were more likely to hold positive implicit attitudes after watching the recovery than symptoms video, particularly when attending to similarities