Positive Solutions of a Second-Order Nonlinear Neutral Delay Difference Equation

The purpose of this paper is to study solvability of the second-order nonlinear neutral delay difference equation Δ(a(n,ya1n,…,yarn)Δ(yn+bnyn-τ))+f(n,yf1n,…,yfkn)=cn,  ∀n≥n0. By making use of the Rothe fixed point theorem, Leray-Schauder nonlinear alternative theorem, Krasnoselskill fixed point theorem, and some new techniques, we obtain some sufficient conditions which ensure the existence of uncountably many bounded positive solutions for the above equation. Five nontrivial examples are given to illustrate that the results presented in this paper are more effective than the existing ones in the literature

Causative agent distribution and antibiotic therapy assessment among adult patients with community acquired pneumonia in Chinese urban population

<p>Abstract</p> <p>Background</p> <p>Knowledge of predominant microbial patterns in community-acquired pneumonia (CAP) constitutes the basis for initial decisions about empirical antimicrobial treatment, so a prospective study was performed during 2003–2004 among CAP of adult Chinese urban populations.</p> <p>Methods</p> <p>Qualified patients were enrolled and screened for bacterial, atypical, and viral pathogens by sputum and/or blood culturing, and by antibody seroconversion test. Antibiotic treatment and patient outcome were also assessed.</p> <p>Results</p> <p>Non-viral pathogens were found in 324/610 (53.1%) patients among whom <it>M. pneumoniae </it>was the most prevalent (126/610, 20.7%). Atypical pathogens were identified in 62/195 (31.8%) patients carrying bacterial pathogens. Respiratory viruses were identified in 35 (19%) of 184 randomly selected patients with adenovirus being the most common (16/184, 8.7%). The nonsusceptibility of <it>S. pneumoniae </it>to penicillin and azithromycin was 22.2% (Resistance (R): 3.2%, Intermediate (I): 19.0%) and 79.4% (R: 79.4%, I: 0%), respectively. Of patients (312) from whom causative pathogens were identified and antibiotic treatments were recorded, clinical cure rate with β-lactam antibiotics alone and with combination of a β-lactam plus a macrolide or with fluoroquinolones was 63.7% (79/124) and 67%(126/188), respectively. For patients having mixed <it>M. pneumoniae </it>and/or <it>C. pneumoniae </it>infections, a better cure rate was observed with regimens that are active against atypical pathogens (e.g. a β-lactam plus a macrolide, or a fluoroquinolone) than with β-lactam alone (75.8% vs. 42.9%, <it>p </it>= 0.045).</p> <p>Conclusion</p> <p>In Chinese adult CAP patients, <it>M. pneumoniae </it>was the most prevalent with mixed infections containing atypical pathogens being frequently observed. With <it>S. pneumoniae</it>, the prevalence of macrolide resistance was high and penicillin resistance low compared with data reported in other regions.</p

Erosion of alloys used for the stages of electrical submersible pumps

Judicious selection of the material used for the stages of an electric submersible pump (ESP) is crucial for a prolonged service life. Working in high-velocity fluids carrying solid particles, the stage surfaces are subjected to solid particle impingement and thus erosion defects arise. Moreover, subsequent erosion-corrosion synergy brings additional threats to the ESPs operating in corrosive environments. In this report, jet impingement tests were conducted to evaluate the performance of three alloys under erosive and corrosive conditions. The tested materials include two Ni-Resist cast irons — wear-resistant materials commonly used for ESP stages — and one superduplex stainless steel (SDSS) that is famous for high strength and extraordinary corrosion resistance. The erosion rate of each material, along with its dependence on jet impingement angle, is quantified in terms of overall volume loss and localized depth loss. Tap water and salt solution are used as particle carrier in parallel to study the synergy between erosion and corrosion. The erosion mechanism of different phases, as well as its dependence on particle impingement conditions, are discussed. Finally, the applicability of substituting Ni-Resist cast irons with SDSS to cope with highly corrosive conditions is assessed based on the experiment results.Singapore Maritime Institute (SMI)This research is funded by the Singapore Maritime Institute under the Asset Integrity & Risk Management (AIM) R&D Programme Project SMI-2015-OF-03

Optimization Design and Experimental Verification for the Mixed-Flow Fan of a Stratospheric Airship

Large-flow, high-pressure fans are required to improve the shape-keeping and flight-height-adjusting ability of stratospheric airships. This study optimizes and analyzes a fan MIX-130 suitable for a stratospheric airship. Five design parameters are selected to optimize the fan&rsquo;s static pressure rise and efficiency: impeller outlet installation angle, installation angle increment, blade thickness, diffuser tilt angle, and L16(45) orthogonal test for optimization research. Based on the optimization results, the fan is processed, a fan test bench is built to verify the accuracy of the fan numerical analysis method, and the fan&rsquo;s performance curve in the stratosphere environment is given. The results demonstrate that after optimization, the static pressure rise in the MIX-130 fan increases by 47.5%, and the efficiency increases by 8%. The performance test data of the MIX-130 fan are consistent with the numerical analysis results. Furthermore, the flow pressure curve is significantly improved compared with the existing fan, satisfying the requirements of airship flight missions. The fan structure optimization and testing methods presented in this manuscript can provide a reference for designing and testing stratospheric airship fans

Successful treatment of pulmonary Nocardia farcinica infection with linezolid: case report and literature review

Nocardia infection is rare but potentially fatal. Therapy of Nocardia infection remains difficult. Linezolid, a novel oxazolidinone antibiotic, has proven to be effective, but clinical data are limited. Here we describe a case of a 45-year-old man with pulmonary N. farcinica infection following a liver transplantation. The initial therapy was trimethoprim-sulfamethoxazole, which showed no effect. According to susceptibility test, linezolid was administered with clearly improving the patient's condition. The treatment was stopped for anemia as drug related adverse event, and the therapy lasted for as long as 5 months. At the end of treatment clinical cure was confirmed and anemia reversed after discontinuation of linezolid. We also analyzed the clinical data of previously published reports by literature review, focusing on the efficacy and safety of linezolid treatment for Nocardia infection

A Thermal Fluid–Solid Coupling Simulation of Gas Fuel Control Valves for High-Precision Gas Turbines

Gas fuel control valves play important roles in the control of gas flow in high-precision gas turbines. To clarify the influence of coupling between the structure and the fluid system, a thermal fluid–solid coupling mechanism is presented based on numerical investigations carried out using a dynamic mesh technique. Valve core deformation can affect the outlet gas flow accuracy. At 2% valve opening, the gas temperature contributes 93% to the deformation. The effect of deformation on the flow accuracy at 6% valve opening and 4% valve opening is increased by 4.8% and 7.3%, respectively. The fluctuation range of the gas temperature and pressure in front of the valve should be strictly controlled to ensure the high precision and high stability of the outlet flow. These results help to clarify the processes that occur in the valve flow path, leading to the flow control instability observed in the control valve