406 research outputs found
Investigation on Performance of Various Power Control Strategies with Bifilar Coil for Induction Surface Melting Application
No full textIn recent years, induction heating applications assisted by electronic power control have been very appealing. For melting applications, induction heating is widely used as it seems to be appropriate and provides higher efficiency, zero pollutants, non-contamination of material, etc. in comparison with conventional heating. The conventional variable frequency control scheme is not sufficient for melting applications because of its high switching loss, low efficiency, and lower heat rate. A superlative control technique is required to control the output power smoothly, for a high heating rate with minimum power loss, and to lower the number of components. In this paper, a capacitorless self-resonating bifilar coil is proposed for induction surface melting applications. The performance of the system in terms of modular losses, heat rate, and efficiency is analyzed for various power methods such as pulse duty cycle control, phase shift control, pulse density modulation control, and asymmetric duty cycle control. An experimental validation is performed for the 1 kW prototype, and the heating rate, efficiency, and modular losses are calculated. The control technique is digitally validated using a PIC16F877A microcontroller with 30 kHz switching frequency. The temperature distribution is analyzed using a FLIR thermal imager. Among the tested methods, pulse density modulation-based control provides smooth and varied power control from 0% to 100% with minimum modular losses. The efficiency of the system is 89% at a rated output power and is greater than 85% for pulse density modulation control with a fast heating rate
Diversity and Distribution of Hard Fouling Phylum Arthropoda andMollusks in Various Substratums at The South-East Coast of Cuddalore,Tamilnadu, India
No full textVengadesh K, Prasanth R M, Udhayadevi M and Sureshkumar
POLYMER MODIFIED ASPHALT NANOCOMPOSITES
No full textAsphalt one of the versatile materials of antique, inspite of its compositional
variations and complexities, widely employed in various applications like water
proofing, paving etc. Due to the complex physical and chemical nature, Asphalt
seldom performs well, without any modification. Amidst other materials, polymers
found to be most suitable for modifying asphalt to suit the application demands.
Nanomaterials, particularly invention of nanoclays, have enhanced the properties
of polymers manifold when introduced in polymer. Polymer Nanocomposites thus
obtained emerge with innovative properties which are not available with existing
polymers. Similar to the effect of nanoclay in polymer, polymers improve the
properties of asphalt. The hypothesis behind this work is to combine the
advantages of nanoclay in polymer and polymer in asphalt by introducing, polymer
and nanoclay in asphalt. Two different nanoclays, Cloisite 20A and Dellite 43B,
were introduced along with EVA by different methods such as Physical Mixing and
Melt Blending. This gave rise to Polymer Modified Asphalt Nanocomposites
(PMAN) a new class of material. Thermal, morphological, structural and
rheological properties were studied. Based on the above studies, fuel resistance
PMAN with EMA, EVA and SBS developed. Also, flammability of PMAN was
studied by developing new test method using Limiting Oxygen Index equipment.
From this research work, new class of materials (PMAN) based on polymer and
nanoclay with improved rheological and performance properties, fuel resistance
were developed
Steroid maintenance in repeat kidney transplantation: Influence of induction agents on outcomes
No full textThe influence of steroid maintenance on the outcomes of repeat kidney transplant (RKT) recipients with respect to induction type is unclear. Using the Organ Procurement and Transplant Network/United Network of Organ Sharing (OPTN/UNOS) database, we identified patients (≥18 years) who underwent deceased donor RKT from January 2000 to December 2008 after receiving induction with rabbit-antithymocyte globulin (r-ATG), alemtuzumab or an IL-2 receptor blocker (IL-2B) and were discharged on a calcineurin inhibitor/mycophenolate mofetil regimen with or without steroids. Of 5634 patients, 3643 received r-ATG (steroid = 3157, no-steroid = 486), 448 alemtuzumab (steroid = 196, no-steroid = 252) and 1543 an IL-2B (steroid = 1465, no-steroid = 78). Unadjusted graft survivals were similar for the no-steroid versus steroid groups for induction with r-ATG [hazard ratio (HR) 0.85 and 95% confidence interval (95% CI) 0.70-1.03, P = 0.10], alemtuzumab (HR 0.76, 95% CI 0.51-1.14, P = 0.18) and IL-2B (HR 0.77, 95% CI 0.56-1.70, P = 0.23). In the adjusted model, steroid use improved graft survival in alem-tuzumab (HR 0.44, 95% CI 0.25-0.76, P = 0.003) but not in the r-ATG (HR 0.86, 95% CI 0.68-1.09, P = 0.21) or IL-2B (HR 0.98, 95% CI 0.56-1.70, P = 0.94) groups. Steroid use was asso-ciated with inferior patient survival in unadjusted (HR 1.30, 95% CI 1.17-1.44, P <0.001) and adjusted (HR 1.29, 95% CI 1.14-1.45, P <0.001) models for r-ATG induction, whereas this was not observed with alemtuzumab (unadjusted HR 1.11, 95% CI 0.89-1.37, P = 0.36; adjusted HR 0.90, 95% CI 0.68-1.20, P = 0.49) or IL-2B (unadjusted HR 1.01, 95% CI 0.87-1.18, P = 0.87; adjusted HR 1.15, 95% CI 0.97-1.38, P = 0.12) inductions. Our study showed a graft survival benefit in the alemtuzumab- and patient death risk in the r-ATG-induced RKT recipients discharged on steroids
Potential diagnostic and prognostic biomarkers for adenovirus respiratory infection in children and young adults
No full textHuman Adenoviruses (HAdV) are known to be potentially associated with strong inflammatory responses and morbidity in pediatric patients. Although most of the primary infections are self-limiting, the severity of clinical presentation, the elevation of the white blood cell count and inflammatory markers often mimic a bacterial infection and lead to an inappropriate use of antibiotics. In infections caused by HAdV, rapid antigen detection kits are advisable but not employed routinely; costs and feasibility of rapid syndromic molecular diagnosis may limit its use in the in-hospital setting; lymphocyte cultures and two-sampled serology are time consuming and impractical when considering the use of antibiotics. In this review, we aim to describe the principal diagnostic tools and the immune response in HAdV infections and evaluate whether markers based on the response of the host may help early recognition of HAdV and avoid inappropriate antimicrobial prescriptions in acute airway infections
Brugia filariasis differentially modulates persistent Helicobacter pylori gastritis in the gerbil model
No full textIn select Helicobacter pylori-infected populations with low gastric cancer, nematode coinfections are common and both helicobacter gastritis and filariasis are modeled in gerbils. We evaluated gastritis, worm counts, tissue cytokine gene expression levels and Th1/Th2-associated antibody responses in H. pylori and Brugia pahangi mono- and coinfected gerbils. H. pylori-associated gastritis indices were significantly lower 21 weeks post-infection in coinfected gerbils (p ≤ 0.05) and were inversely proportional to worm counts (r2 = −0.62, p < 0.003). Additionally, IFN-γ, IL-1β, CXCL1, IL-4 and IL-10 mRNA levels in the gastric antrum reflected a significant host response to gastric H. pylori and as well as systemic filariasis (p ≤ 0.05). Despite increasing worm burden (p < 0.05), gastritis progressed in coinfected gerbils (p < 0.03) becoming equivalent to H. pylori-infected gerbils at 42 weeks (p = 0.7). Pro- and anti-inflammatory mediator mRNA levels were notably downregulated in B. pahangi infected gerbils below uninfected control values, suggesting hyporesponsiveness to B. pahangi. Consistent with an increasing Th1 response to H. pylori, IgG2a (p < 0.01), IL-1β (p = 0.04) and CXCL1 (p = 0.006) responses significantly increased and IL-4 (p = 0.05) and IL-10 (p = 0.04) were decreased in coinfected gerbils at 42 weeks. Initial systemic responses to B. pahangi resulted in attenuated gastritis in coinfected gerbils, but subsequent filarid-associated hyporesponsiveness appears to have promoted H. pylori gastritis.National Institutes of Health (U.S.) (NIH grant R01 AI 0337750)National Institutes of Health (U.S.) (Grant P30-ES002109)National Institutes of Health (U.S.) (Grant P01 CA 028842)National Institutes of Health (U.S.) (Grant T32 RR 07036
Morphology of conducting polymeric coatings: Quantitative comparison between theory and experiment
No full textThe density profile of electrosynthesized polymeric layers on carbon fibers is obtained from gravimetric and scanning electron microscopy (SEM) data. The coating density ρ is found to decrease with increasing radial distance, r, subject to the power law ρ(r)∝1/√r. Based on a modified diffusion-limited aggregation (DLA) model, it is shown that lattice Monte Carlo simulation of the coating process predicts the experimentally observed power law exponent. © 2003 Elsevier Science Ltd. All rights reserved.link_to_subscribed_fulltex
Enteric Infection with Citrobacter rodentium Induces Coagulative Liver Necrosis and Hepatic Inflammation Prior to Peak Infection and Colonic Disease
No full textAcute and chronic forms of inflammation are known to affect liver responses and susceptibility to disease and injury. Furthermore, intestinal microbiota has been shown critical in mediating inflammatory host responses in various animal models. Using C. rodentium, a known enteric bacterial pathogen, we examined liver responses to gastrointestinal infection at various stages of disease pathogenesis. For the first time, to our knowledge, we show distinct liver pathology associated with enteric infection with C. rodentium in C57BL/6 mice, characterized by increased inflammation and hepatitis index scores as well as prominent periportal hepatocellular coagulative necrosis indicative of thrombotic ischemic injury in a subset of animals during the early course of C. rodentium pathogenesis. Histologic changes in the liver correlated with serum elevation of liver transaminases, systemic and liver resident cytokines, as well as signal transduction changes prior to peak bacterial colonization and colonic disease. C. rodentium infection in C57BL/6 mice provides a potentially useful model to study acute liver injury and inflammatory stress under conditions of gastrointestinal infection analogous to enteropathogenic E. coli infection in humans.United States. Army Research Office (Institute for Soldier Nanotechnology grant 6915539 (SRT))National Institutes of Health (U.S.) (Grant P01 CA026731)National Institutes of Health (U.S.) (Grant P30 ES02109)National Institutes of Health (U.S.) (Toxicology Training grant ES-070220
Localising imbalance faults in rotating machinery
No full textThis thesis presents a novel method of locating imbalance faults in rotating
machinery through the study of bearing nonlinearities. Localisation in this work
is presented as determining which discs/segments of a complex machine are
affected with an imbalance fault. The novel method enables accurate
localisation to be achieved using a single accelerometer, and is valid for both
sub and super-critical machine operations in the presence of misalignment and
rub faults.
The development of the novel system for imbalance localisation has been
driven by the desire for improved maintenance procedures, along with the
increased requirement for Integrated Vehicle Health Management (IVHM)
systems for rotating machinery in industry. Imbalance faults are of particular
interest to aircraft engine manufacturers such as Rolls Royce plc, where such
faults still result in undesired downtime of machinery. Existing methods of
imbalance localisation have yet to see widespread implementation in IVHM and
Engine Health Monitoring (EHM) systems, providing the motivation for
undertaking this project.
The imbalance localisation system described has been developed primarily for
a lab-based Machine Fault Simulator (MFS), with validation and verification
performed on two additional test rigs. Physics based simulations have been
used in order to develop and validate the system. An Artificial Neural Network
(ANN) has been applied for the purposes of reasoning, using nonlinear features
in the frequency domain originating from bearing nonlinearities. The system has
been widely tested in a range of situations, including in the presence of
misalignment and rub faults and on a full scale aircraft engine model. The novel
system for imbalance localisation has been used as the basis for a methodology
aimed at localising common faults in future IVHM systems, with the aim of
communicating the results and findings of this research for the benefit of future
research. The works contained herein therefore contribute to scientific
knowledge in the field of IVHM for rotating machinery
Fast N-CO rotational equilibria in twist-boat conformations of <i>N</i>-ethoxycarbonyl-<i>r-</i> 2<i>, c</i>-6-diphenylpiperidin-4-ones and <i>N</i>-ethoxycarbonyl-<i>r</i>-2,<i> c</i>-6-diphenylpiperidines
No full text614-627The effects of N-COOEt and alkyl substituents
on the preferred conformations of six N-ethoxycarbonyl-r-2 , c-6-diphenylpiperidin-4-ones
11-16 and six corresponding piperidines 23-28 have been
determined. The spectral data and the calculated dihedral angles indicated
that the N-ethoxycarbonyl derivatives 11, 16, 23 and 24 adopt flattened-boat
conformations
while the X-ray crystal structure of 23
showed a distorted boat conformation. The other unsymmetrically substituted N-ethoxycarbonyl
derivatives 12-15 and 25-28 prefer twist-boat conformations in solution.
The preferred conformation of 15 obtained through X-ray crystallography is
also a twist-boat. The barriers for the N-CO rotation determined using variable
temperature 1H NMR studies for the N-ethoxycarbonyl derivatives
11 and 14 are 47.9 and 50.5 kJ mol-1, respectively.
The N-CO rotation barriers are lower than those observed for N-NO rotation in N-nitroso-r-2,
c-6-dimethylpiperidine and N-nitroso-
r-2, c-6-diphenylpiperidines.
The conformational preferences of the N-ethoxycarbonyl deri vatives 11-16
and 23-28 has also been determined by the semiempirical molecular orbital
calculations (AM1 of MOPAC 6)
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