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Pump System (pump + system)
Selected AbstractsPotential multidrug resistance gene POHL: An ecologically relevant indicator in marine spongesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2001Anatoli Krasko Abstract Sponges are sessile filter feeders found in all aquatic habitats from the tropics to the arctic. Against potential environmental hazards, they are provided with efficient defense systems, e.g., protecting chaperones and/or the P-170/multidrug resistance pump system. Here we report on a further multidrug resistance pathway that is related to the pad one homologue (POH1) mechanism recently identified in humans. It is suggested that proteolysis is involved in the inactivation of xenobiotics by the POH1 system. Two cDNAs were cloned, one from the demosponge Geodia cydoniumand a second from the hexactinellid sponge Aphrocallistes vastus. The cDNA from G. cydonium, termed GCPOHL, encodes a deduced polypeptide with a size of 34,591 Da and that from A. vastus, AVPOHL, a protein of a calculated Mr of 34,282. The two sponge cDNAs are highly similar to each other as well as to the known sequences from fungi (Schizosaccharomyces pombe and Saccharomyces cerevisiae) and other Metazoa (from Schistosoma mansoni to humans). Under controlled laboratory conditions, the expression of the potential multidrug resistance gene POHL is, in G. cydonium, strongly upregulated in response to the toxins staurosporin (20 ,M) or taxol (50 ,M); the first detectable transcripts appear after 1 d and reach a maximum after 3 to 5 d of incubation. The relevance of the expression pattern of the G. cydonium gene POHL for the assessment of pollution in the field was determined at differently polluted sites in the area around Rovinj (Croatia; Mediterranean Sea, Adriatic Sea). The load of the selected sites was assessed by measuring the potency of XAD-7 concentrates of water samples taken from those places to induce the level of benzo[a]pyrene monooxygenase (BaPMO) in fish and to impair the multidrug resistance (MDR)/P-170 extrusion pump in clams. These field experiments revealed that the levels of inducible BaPMO activity in fish and of the MDR potential by the water concentrates are highly correlated with the level of expression of the potential multidrug resistance gene POHL in G. cydonium. This report demonstrates that the detoxification POH pathway, here mediated by the G. cydonium GCPOHL gene, is an additional marker for the assessment of the environmental load in a given marine area. [source] Dynamic operation plan of a combined fuel cell cogeneration, solar module, and geo-thermal heat pump system using Genetic AlgorithmINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2007Shin'ya Obara Abstract A chromosome model that simulates the operation patterns of an energy system was introduced into a simple Genetic Algorithm, and a method of dynamic optimization was developed. This paper analyses the operation planning of an energy system that uses in combination a solar power module, proton-exchange membrane fuel cell cogeneration (PEMFC-CGS) with methanol steam reforming, a geo-thermal heat pump, heat storage and battery, commercial power, and a kerosene boiler. The hours of operation of each energy device and the rate of the energy output were calculated by having introduced the analysis program developed by this study. Three objective functions: (a) minimization of operation cost; (b) minimization of the error of demand-and-supply balance; and (c) minimization of the amount of greenhouse gas discharge were given to the optimization analysis of the system. Furthermore, the characteristics of the system operation planning under each objective function are described. Copyright © 2007 John Wiley & Sons, Ltd. [source] Adiabatic capillary tube flow of carbon dioxide in a transcritical heat pump cycleINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2007Neeraj Agrawal Abstract Flow characteristics of an adiabatic capillary tube in a transcritical CO2 heat pump system have been investigated employing the homogeneous model. The model is based on fundamental equations of mass, energy and momentum which are solved simultaneously. Two friction factor empirical correlations (Churchill, Lin et al., Int. J. Multiphase Flow 1991; 17(1):95,102) and four viscosity models (Mcadams, Cicchitti, Dukler and Lin) are comparatively used to investigate the flow characteristics. Choked condition at the outlet is also investigated for maximum mass flow rate. Subcritical and supercritical thermodynamic and transport properties of CO2 are calculated employing a precision property code. Choice of viscosity model causes minor variation in results unlike in chlorofluorocarbons (CFCs) refrigerants. Relationships between cooling capacity with capillary tube diameter, length and maximum mass flow rate are presented. A lower evaporating temperature yields a larger cooling capacity due to the unique thermodynamic properties of CO2. It is also observed that an optimum cooling capacity exists for a specified capillary tube. Copyright © 2006 John Wiley & Sons, Ltd. [source] Experimental investigation of the performance of a solar-assisted ground-source heat pump system for greenhouse heatingINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2005Onder Ozgener Abstract The main objective of the present study is to investigate the performance characteristics of a solar-assisted ground-source heat pump system (SAGSHPS) for greenhouse heating with a 50 m vertical 1¼ in nominal diameter U-bend ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir (568 degree days cooling, base: 22°C, 1226 degree days heating, base: 18°C), Turkey. Based upon the measurements made in the heating mode, the heat extraction rate from the soil is found to be, on average, 54.08 Wm,1 of bore depth, while the required borehole length in meter per kW of heating capacity is obtained as 12.57. The entering water temperature to the unit ranges from 8.2 to 16.2°C, with an average value of 9.1°C. The greenhouse air is at a maximum day temperature of 25°C and night temperature of 14°C with a relative humidity of 40%. The heating coefficient of performance of the heat pump (COPHP) is about 2.13 at the end of a cloudy day, while it is about 2.84 at the end of sunny day and fluctuates between these values in other times. The COP values for the whole system are also obtained to be 5,15% lower than COPHP. Copyright © 2004 John Wiley & Sons, Ltd. [source] QSAR study of ,-lactam antibiotic efflux by the bacterial multidrug resistance pump AcrB,JOURNAL OF CHEMOMETRICS, Issue 5 2004Márcia M. C. Ferreira Abstract AcrAB-TolC is the most important efflux pump system of Gram-negative bacteria, responsible for their resistance to lipophilic and amphilic drugs. In this work, HCA,PCA studies were performed to investigate the relationship between efflux activities (negative logarithm of minial inhibitor concentration, pMIC) of three strains of S. thypimurium with respect to ,-lactams, and to analyze the relationship between lipophilicity parameters calculated by different methods. The analyses demonstrate that pMICs strongly depend on properties of both bacterial strains and drug molecules, and that lipophilicity parameters do not necessarily contain the same information about the drugs. QSAR studies have shown that the calculated lipophilicities, in some cases, are non linearly related to the pMICs originated by active AcrAB-TolC bacterial pumps, due to the existence of ,-lactams with nitrogen- and sulfur-rich substituents. Among the most important ,-lactam molecular properties quantitatively related to pMICs are lipophilicity and electronic and hydrogen,bonding properties. Parameters describing these properties were included in the QSAR study to obtain parsimonius regression models for MICs. ,-Lactams were classified as good, moderately good and poor AcrAB-TolC substrates. Their stereoelectronic molecular properties, especially the Y-component of the molecular dipole moment and hydrogen binding properties, reflected this classification. Copyright © 2004 John Wiley & Sons, Ltd. [source] Implementation of an intravenous medication infusion pump system: implications for nursingJOURNAL OF NURSING MANAGEMENT, Issue 2 2008Marilyn Bowcutt MSN Aim, To assess perceptions of nurses regarding the implementation of intravenous medication infusion system technology and its impact on nursing care, reporting of medication errors and job satisfaction. Background, Medication errors are placing patients at high risk and creating an economic burden for hospitals and health care providers. Infusion pumps are available to decrease errors and promote safety. Methods, Survey of 1056 nurses in a tertiary care Magnet hospital, using the Infusion System Perception Scale. Response rate was 65.43%. Results, Nurses perceived the system would enhance their ability to provide quality nursing care, reduce medication errors. Job satisfaction was related to higher ratings of the management team and nursing staff. Perceptions verified the pump was designed to promote safe nursing practices. Conclusions, It is important to consider relationships with job satisfaction, safe nursing practice and the importance of ratings of nursing staff and management teams when implementing infusion technology. Implications for nursing management, Infusion pumps are perceived by nurses to enhance safe nursing practice. Results stress the importance of management teams in sociotechnological transformations and their impact on job satisfaction among nurses. [source] Optimal Moving Angle of Pusher Plate in Occlusive-Type Pulsatile Blood PumpARTIFICIAL ORGANS, Issue 7 2010Hyuk Choi Abstract Since the occlusive-type pulsatile extracorporeal blood pump (Twin-Pulse Life Support System; Seoul National University, Seoul, Korea) received the CE mark of the European Directives and Korea Food and Drug Administration approval (2004) for short-term applications as an extracorporeal life support system, the pump system has been tested for hemolysis. This pump system was recently upgraded with an ameliorated pusher plate to reduce hemolysis. In this study, numerical analysis and in vitro tests were performed to determine the optimal conditions for increasing the durability of the blood sac and pump output. During the simulation, the minimum sliding interface force (SIF) for the angle of the pusher plate movement (PPM) was calculated (40,70°). In the in vitro durability test, the angle of the PPM was increased gradually from 40 to 70° in 10° increments, and the mean time to failure (MTTF) of the blood sac was calculated. Fifteen tests were conducted for each case: 40, 50, 60, and 70° (n = 15 each). The MTTF of the blood sac was defined as the time when a crack of the blood sac occurred. The longer lifetime of the blood sac at 60° of the PPM (297.0 h) than that at 50° (197.6 h) was attributed to the lower SIF value (,0.13, normalized value) at 60° of the PPM. [source] Bridge-to-recovery from Acute Myocarditis in a 12-year-old ChildARTIFICIAL ORGANS, Issue 6 2004Holger Hotz Abstract:, Fulminant myocarditis causes substantial morbidity and mortality, especially in children and young adults. Mechanical circulatory support has become the standard therapy to bridge patients with intractable heart failure to either transplantation or myocardial recovery. Yet, successful weaning from biventricular support with full recovery is extremely rare in the pediatric population. This report describes the successful use of the MEDOS HIA ventricular assist device to bridge a 12-year-old girl to myocardial recovery in a biventricular bypass configuration. The left and right ventricle were completely off-loaded by the pumps and the device provided sufficient cardiac output to normalize end-organ function. Anticoagulation was maintained with i.v. heparin infusion. No neurological complications were detectable and the pump system was free of any macroscopic thrombi. After 19 days of support, cardiac function had recovered and the patient was successfully weaned from the device. Following physical rehabilitation, the patient was discharged home. [source] Physical Model-Based Indirect Measurements of Blood Pressure and Flow Using a Centrifugal PumpARTIFICIAL ORGANS, Issue 8 2000Tadashi Kitamura Abstract: This article describes a technique offering indirect measurements of pump pressure differential and flow with certain accuracy independent of changes in blood viscosity. This technique is based on noninvasive measurements of the motor current and rotation speed using the physical model equations of the centrifugal pump system. Blood viscosity included in the coefficients of the dynamic equations is first estimated, and then substitution of the estimated viscosity into the steady equations of the model provides pump flow and pressure differential. In vitro tests using a Capiox pump showed a sufficient linear correlation between actual values and their estimates for pressure differential and pump flow. An in vivo test using a 45 kg sheep showed that the proposed algorithm needs robustness for the convergence of estimates of viscosity. An overall evaluation, however, of the developed algorithm/model showed indications of success in terms of efficient computation and modeling. [source] In vivo evaluation of an implantable portal pump system for augmenting liver perfusionBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2000L. R. Jiao Background Increasing portal inflow in cirrhosis using a mechanical pump reduces portal venous pressure and improves liver function. A pump has been developed for portal vein implantation in human cirrhosis. This study describes the initial in vivo evaluation in a porcine model. Methods Five Large White pigs underwent laparotomy and exposure of the liver. Flow in the hepatic artery, portal vein and hepatic microcirculation was monitored continuously. Hepatic tissue oxygenation was measured by near-infrared spectroscopy. After baseline measurements the pump was inserted into the portal vein. Pump flow rate was then increased stepwise to 50 per cent over the baseline value for a period of 2 h. The pump was then stopped for 20 min and left in situ while continuing to collect systemic and hepatic haemodynamic data. The animal was killed and biopsies for histological examination were taken from the liver, small intestine and spleen. Results The baseline total hepatic blood flow was 626(39) ml/min; the hepatic artery supplied 18·4(2·1) per cent and the portal vein 81·6(2·1) per cent. The pump was inserted successfully in all animals without surgical complications. During surgical insertion of the pump, the temporary portal vein occlusion resulted in a significant rise in hepatic artery blood flow (22(3) per cent; P < 0·01 versus baseline). Portal vein flow was augmented by pumping; there was a significant correlation between the pump motor speed and portal vein flow (P < 0·0001). This inflow correlated directly with flow in the hepatic microcirculation and hepatic tissue oxygenation (P < 0·001). The pump ran satisfactorily throughout the study. Histological examination revealed no evidence of structural damage to the liver or ischaemic changes in the small intestine or spleen. Conclusion It is technically possible and safe to insert an implantable pump in the portal vein. Portal venous blood flow can be increased up to 50 per cent with a resultant increase in flow in the hepatic microcirculation and hepatic oxygenation and without adverse effects on either hepatic or systemic haemodynamics. © 2000 British Journal of Surgery Society Ltd [source] Experimental model of a variable capacity compressorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2009C. Aprea Abstract The refrigeration and heat pump systems are lately characterized by a remarkable evolution period. The principal reasons that have determined changes are the substitution of environmentally unfriendly refrigerants and the energy saving necessity. As fundamental component of a vapour compression plant, the compressor is an object of optimizations; the variation of the compressor speed, obtained regulating the supply current frequency of the compressor motor, allows to obtain energy savings. The principal aim of this paper is the determination of an experimental model that represents the variable speed reciprocating compressor working. In particular, equations that allow to get the refrigerant mass flow rate, the compressor input power and the cooling capacity in terms only of the frequency are obtained. The experimental model allows to determine the optimum frequency for each working condition and then the related energy saving. Copyright © 2008 John Wiley & Sons, Ltd. [source] Study on carbon dioxide gas cooler heat transfer process under supercritical pressuresINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 14 2002Jianfeng Wang Abstract In carbon dioxide transcritical air-conditioning and heat pump systems, the high-pressure-side heat exchanger operating at supercritical pressures is usually called as gas cooler. The carbon dioxide gas cooler displays much difference from the traditional heat exchangers employing constant property fluids. The commonly used logarithmic mean temperature difference (LMTD) and effectiveness,heat transfer unit (,-NTU) fail for the gas cooler design calculation as the carbon dioxide properties change sharply near the critical or pseudo-critical point in the heat transfer processes. The new effective heat transfer temperature difference expression for variable fluid property derived by the authors is verified by numeric simulation of the carbon dioxide gas cooler. Moreover, the available correlated models for the cooled carbon dioxide supercritical heat transfer are used to simulate the gas cooler. Detail analysis is made for the deviations among the different models, and for the distributions of local convective coefficient, heat flux, and local temperature of carbon dioxide along the flow path in the gas cooler. Copyright © 2002 John Wiley & Sons, Ltd. [source] Fundamental and practical aspects of ultrahigh pressure liquid chromatography for fast separationsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 8 2007Naijun Wu Abstract The ongoing development of HPLC has been focused on increasing the speed and efficiency of separations over the past decade. The advances in separation speed have been primarily related to the development of column technology and instrumentation. Relatively short columns packed with sub-2 ,m particles provide high-speed separations while maintaining or increasing resolution. Ultrahigh pressure pump systems have been developed to overcome the high-pressure drop generated by such sub-2 ,m packings. In this review, fundamental and practical aspects of ultrahigh pressure or ultrahigh performance liquid chromatography (U-HPLC) are discussed. Applications of fast U-HPLC separations are also presented. [source] | |||||||||||||