1,001 research outputs found

    Ceramic coatings on smooth surfaces

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    A metallic coating is plasma sprayed onto a smooth surface of a metal alloy substitute or on a bond coating. An initial thin ceramic layer is low pressure sprayed onto the smooth surface of the substrate or bond coating. Another ceramic layer is atmospheric plasma sprayed onto the initial ceramic layer

    Champion Networks in Federated Interorganizational Systems: Case Studies in Telemedicine

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    Champions are critical to the success of an information system implementation. Research shows that success in implementing a large information system may hinge on there being more than one type of champion. This study investigates the types of champions used in federated inter-organizational systems (FIOS) in a state telemedicine context. Case studies were conducted in Georgia, Pennsylvania, Ohio, and Wisconsin to identify the network of champions in state telemedicine systems. We found that FIOS that relied on a network of champions, including a sponsorship champion at the state level, as well as a technical champion and user champion at site locations, were more successful than those that lacked such a network. We suggest that our model of champions in FIOS applies not only to state telemedicine, but also to any large-scale system implementation spanning a federation of loosely coupled organizations

    Kinetic modeling of free radical polymerization of styrene initiated by the bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy) hexane

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    This paper deals with the kinetic study of bulk free radical polymerization of styrene initiated with the commercial bifunctional initiator 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane (Lupersol 256). The polymerization kinetics is investigated by DSC measurement for temperatures between 80 and 110°C and for initiator initial concentration from 0.115 up to 0.46 mol%. The experimental conversion and reaction rate are compared and discussed with the calculated values. For modeling the polymerization rate, a reaction scheme similar to the one given by Yoon and Choi (Polymer 1992;33(21):4582–4591) has been used and adapted. A detailed diffusional and semi-empirical model proposed by Chiu et al. (Macromolecules 1983;16(3):348–357) has been modified by Rouge (Etude de la polymérisation radicalaire du styrène initiée par un amorceur bifonctionnel dans un réacteur tubulaire à recyclage, Diploma work, DC, EPF, Lausanne, 1997) in order to describe these results. The model allows the description of the number molecular weight, but the polydispersity is underestimated for conversion higher than 70%. For temperature higher than 100°C, thermal initiation must be taken into account. The efficiency factor is found close to 1, but seems to decrease for temperatures above 100°C

    Microchannel reactors for fast periodic operation: the catalytic dehydrogenation of isopropanol

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    A microchannel reactor specially designed for periodic operation and a process to deposit a catalyst, g-alumina, inside the reactor channels were developed. The hydrodynamics of the reactor was characterised. Although the flow in the microchannels is laminar, a uniform radial concentration profile and consequently a narrow residence time distribution were obtained. Depending on the manufacturing method the Bodenstein number was found to be Bo=ud/Dm=~70. The catalytic coating had no influence on this distribution indicating a uniform deposition of the catalyst within the microchannels. As the inlet function was only slightly modified in the reactors, frequencies of up to 1 Hz could be imposed for periodic operation. The dehydration of isopropanol to propene was chosen as model reaction to study the dynamic behaviour of a microreactor under periodic concentration variations. The kinetics was firstly studied in a conventional fixed-bed reactor with the catalyst developed for the microreactor. Experimental results confirmed the theoretically predicted increase of the reactor performance under periodic operation exceeding the maximum obtainable performance under steady-state conditions

    Double-Lepton Polarization Asymmetries in B_s \rar \phi \ell^+ \ell^- Decay in the Fourth-Generation Standard Model

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    In this paper, we investigate the effects of the fourth generation of quarks on the double-lepton polarization asymmetries in the B_s \rar \phi \ell^+ \ell^- decay. It is shown that these asymmetries in B_s \rar \phi \ell^+ \ell^- decay compared with those of B \rar K \ell^+ \ell^- decay are more sensitive to the fourth-generation parameters. We conclude that an efficient way to establish the existence of the fourth generation of quarks could be the study of these asymmetries in the B_s \rar \phi \ell^+ \ell^- decay.Comment: 25 pages and 7 figure

    Enteric dysbiosis and fecal calprotectin expression in premature infants.

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    BackgroundPremature infants often develop enteric dysbiosis with a preponderance of Gammaproteobacteria, which has been related to adverse clinical outcomes. We investigated the relationship between increasing fecal Gammaproteobacteria and mucosal inflammation, measured by fecal calprotectin (FC).MethodsStool samples were collected from very-low-birth weight (VLBW) infants at ≤2, 3, and 4 weeks' postnatal age. Fecal microbiome was surveyed using polymerase chain reaction amplification of the V4 region of 16S ribosomal RNA, and FC was measured by enzyme immunoassay.ResultsWe enrolled 45 VLBW infants (gestation 27.9 ± 2.2 weeks, birth weight 1126 ± 208 g) and obtained stool samples at 9.9 ± 3, 20.7 ± 4.1, and 29.4 ± 4.9 days. FC was positively correlated with the genus Klebsiella (r = 0.207, p = 0.034) and its dominant amplicon sequence variant (r = 0.290, p = 0.003), but not with the relative abundance of total Gammaproteobacteria. Klebsiella colonized the gut in two distinct patterns: some infants started with low Klebsiella abundance and gained these bacteria over time, whereas others began with very high Klebsiella abundance.ConclusionIn premature infants, FC correlated with relative abundance of a specific pathobiont, Klebsiella, and not with that of the class Gammaproteobacteria. These findings indicate a need to define dysbiosis at genera or higher levels of resolution
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