The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit ...The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.展开更多
In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array vol...In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array voltage and current being used to generate the reference voltage which should be the PV panel’s operating voltage to get maximum available power. A Takagi-Sugeno (T-S) observer has been proposed and designed with non-measurable premise variables and the conditions of stability are given in terms of Linear Matrix Inequality (LMI). The simulation results show the effectiveness and robustness of the proposed method.展开更多
The piston pump is the key power component in the civil aircraft hydraulic system,and the most common pump used in the aviation field is the pressure compensated variable displacement type.In this review paper,a basic...The piston pump is the key power component in the civil aircraft hydraulic system,and the most common pump used in the aviation field is the pressure compensated variable displacement type.In this review paper,a basic introduction to the civil aircraft piston pump is presented,including the classification,structure,working principle,design features,and achievements by some research groups.Then,the future directions of the aircraft pump are reported from various perspectives.Further,the critical technologies are analyzed and summarized in detail from six thrust areas:friction couples,noise reduction,inlet boost,thermal management,fault diagnosis and health management,and mechanical seal.Finally,the challenges and limitations of the research on the aircraft pump are discussed to provide valuable insight for future scholars.展开更多
BACKGROUND Proton pump inhibitors(PPIs)are widely prescribed,often without clear indications.There are conflicting data on its association with mortality risk and hepatic decompensation in cirrhotic patients.Furthermo...BACKGROUND Proton pump inhibitors(PPIs)are widely prescribed,often without clear indications.There are conflicting data on its association with mortality risk and hepatic decompensation in cirrhotic patients.Furthermore,PPI users and PPI exposure in some studies have been poorly defined with many confounding factors.AIM To examine if PPI use increases mortality and hepatic decompensation and the impact of cumulative PPI dose exposure.METHODS Data from patients with decompensated liver cirrhosis were extracted from a hospital database between 2013 to 2017.PPI users were defined as cumulative defined daily dose(cDDD)≥28 within a landmark period,after hospitalisation for hepatic decompensation.Cox regression analysis for comparison was done after propensity score adjustment.Further risk of hepatic decompensation was analysed by Poisson regression.RESULTS Among 295 decompensated cirrhosis patients,238 were PPI users and 57 were non-users.PPI users had higher mortality compared to non-users[adjusted HR=2.10,(1.20-3.67);P=0.009].Longer PPI use with cDDD>90 was associated with higher mortality,compared to non-users[aHR=2.27,(1.10-5.14);P=0.038].PPI users had a higher incidence of hospitalization for hepatic decompensation[aRR=1.61,(1.30-2.11);P<0.001].CONCLUSION PPI use in decompensated cirrhosis is associated with increased risk of mortality and hepatic decompensation.Longer PPI exposure with cDDD>90 increases the risk of mortality.展开更多
Aim: To evaluate the correlation of blood lactate and mixed venous oxygen saturation to predict outcome in off-pump coronary artery bypass grafting. Method: This is a randomized study including 30 patients. Blood lact...Aim: To evaluate the correlation of blood lactate and mixed venous oxygen saturation to predict outcome in off-pump coronary artery bypass grafting. Method: This is a randomized study including 30 patients. Blood lactate and mixed venous oxygen saturation were measured in 4 groups of patients—number of grafts, presence or absence of left main coronary artery disease, ejection fraction and serum creatinine. Blood samples were taken before induction, after grafting, on intensive care unit admission, 24 hours and 48 hours after surgery. The measured blood lactate and mixed venous oxygen saturation are compared to assess the outcomes in terms of duration of ventilation and intensive care unit stay. Results: The blood lactate and mixed venous oxygen saturation values increased post operatively but no statistically significant difference in three groups— number of grafts, left main coronary artery disease and ejection fraction. In serum creatinine group, the blood lactate value was found to be statistically significant after grafting in patients with creatinine <1.5 mg/dl, however, there was a significant disparity in numbers. Conclusion: Mixed venous oxygen saturation is a better predictor of morbidity than blood lactate in terms of intensive care unit stay in patients undergoing off pump coronary artery bypass grafting.展开更多
Numerical simulation of diode-pumped Q-switched Nd:YAG laser leading to the generation of eye-safe signal in singly resonant Intracavity Optical Parametric Oscillator (IOPO) is presented. Starting from rate equations,...Numerical simulation of diode-pumped Q-switched Nd:YAG laser leading to the generation of eye-safe signal in singly resonant Intracavity Optical Parametric Oscillator (IOPO) is presented. Starting from rate equations, the time dependent laser equations have been solved numerically, whereas the space-dependent OPO equations analytically. Our results show that 1.4 J diode laser (810 nm) pulse with 200 msec width, delivers 30 mJ Nd:YAG laser (1064 nm) pulse with 5 n-second width. This Nd:YAG laser further generates 9 mJ eye safe signal (1570 nm) pulse with 2.5 n-second width.展开更多
Our study evaluated the hemodynamic performance of an axial flow blood pump surgically implanted in idealized total cavopulmonary connection(TCPC)models.This blood pump was designed to augment pressure from the inferi...Our study evaluated the hemodynamic performance of an axial flow blood pump surgically implanted in idealized total cavopulmonary connection(TCPC)models.This blood pump was designed to augment pressure from the inferior vena cava(IVC)to the pulmonary circulation.Two Fontan procedures with single and bilateral superior vena cava(SVC)were compared to fit the mechanical supported TCPC physiologies.Computational fluid dynamics(CFD)analyses of two Pump-TCPC models were performed in the analyses.Pressure-flow characteristics,energy efficiency,fluid streamlines,hemolysis and thrombosis analyses were implemented.Numerical simulations indicate that the pump produces pressure generations of 1 mm to 24 mm Hg for rotational speeds ranging from 2000 RPM to 5000 RPM and flow rates of 2 LPM to 4 LPM.Two surgical models incorporated with the pump were found to be insignificant in pressure augmentation and energy boost.The risk assessment of blood trauma and thrombosis generation was evaluated representatively through blood damage index(BDI),particle resident time(PRT)and relative resistant time(RRT).The hemolysis and thrombosis analyses declare the advantage of the pump supported bilateral SVC surgical scheme in balancing flow distribution and reducing the risk of endothelial cell destruction and trauma generation.展开更多
Proton pump inhibitors often are prescribed in combination with clopidogrel to decrease risk of gastrointestinal bleeding after acute coronary syndrome. Clopidogrel is a prodrug that has to be metabolized in the liver...Proton pump inhibitors often are prescribed in combination with clopidogrel to decrease risk of gastrointestinal bleeding after acute coronary syndrome. Clopidogrel is a prodrug that has to be metabolized in the liver to generate the active metabolite. Both medications are metabolized largely by the CYP2C19 enzyme;therefore, concerns exist that a drug-drug interaction during concomitant treatment with clopidogrel and a proton pump inhibitor may result in reduction of platelet inhibition. We have reviewed observational and randomized control studies that have evaluated the potential influence of proton pump inhibitors on the platelet inhibitory effect of clopidogrel, along with cardiovascular outcomes. We also have summarized regulatory and academic guidelines for treatment of patients in which concomitant therapy with clopidogrel and proton pump inhibitors may be indicated. Confounding issues, including differential effects of individual proton pump inhibitors on the pharmacodynamics of clopidogrel and variation in clopidogrel metabolism mediated by CYP2C19 gene polymorphisms, also are discussed.展开更多
Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established. In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar ene...Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established. In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the solar collector was employed to heating. Some of the soil heat exchangers were used to store solar energy in the soil so as to be used in next winter after this heating period; and the others were used to extract cooling energy directly in the soil by circulation pump for air conditioning in summer. After that solar energy began to be stored in the soil and ended before heating period. Three dimensional dynamic numerical simulations were built for soil and soil heat exchanger through finite element method. Simulation was done in different strata month by month. Variation and restoration of soil temperature were studied. Economy and reliability of long term SAGSHP system were revealed. It can be seen that soil temperature is about 3 ℃ higher than the original one after one year's running. It is beneficial for the system to operate for long period.展开更多
Proton pump inhibitors(PPIs)are widely utilized in oncology to treat gastroeso-phageal reflux disease,peptic ulcer disease,and chemotherapy-induced mucosal injury.Emerging evidence has suggested that prolonged use of ...Proton pump inhibitors(PPIs)are widely utilized in oncology to treat gastroeso-phageal reflux disease,peptic ulcer disease,and chemotherapy-induced mucosal injury.Emerging evidence has suggested that prolonged use of PPIs is associated with increased mortality in patients with cancer.The findings of Krishnan et al are proof of this but need to be considered cautiously due to potential confounding factors.This letter raised important methodological concerns,including con-founding by indication,reverse causality,and polypharmacy that can influence the observed association.While PPIs are important in oncology,their advantages and disadvantages should be weighed judiciously by clinicians.Future prospective studies with robust analytical approaches will be required to ascertain more definite causality.展开更多
Proton pump inhibitors(PPIs) are one of the most frequently used medications for upper gastrointestinal diseases. However, a number of physicians have raised concern about the serious side effects of long-term use of ...Proton pump inhibitors(PPIs) are one of the most frequently used medications for upper gastrointestinal diseases. However, a number of physicians have raised concern about the serious side effects of long-term use of PPIs, including the development of gastric cancer. Recent epidemiological studies have reported a significant association between long-term PPI intake and the risk of gastric cancer, even after successful Helicobacter pylori eradication. However, the effects of PPIs on the development of pre-malignant conditions such as atrophic gastritis or intestinal metaplasia are not fully known, suggesting the need for comprehensive and confirmative studies are needed in the future. Meanwhile,several experimental studies have demonstrated the effects of PPIs in reducing chemoresistance in gastric cancer cells by modulating the acidic microenvironment, cancer stemness and signal transducer and activator of transcription 3(STAT3) signaling pathway. The inhibitory effects of PPIs on STAT3 activity may overcome drug resistance and enhance the efficacy of conventional or targeted chemotherapeutic agents. Taken together, PPIs may"play dual role" in gastric carcinogenesis and treatment of gastric cancer.展开更多
Once a nosocomial disease,Clostridium difficile infection(CDI)now appears frequently in the community in the absence of exposure to antibiotics.Prior studies have shown that patients with community-acquired CDI are yo...Once a nosocomial disease,Clostridium difficile infection(CDI)now appears frequently in the community in the absence of exposure to antibiotics.Prior studies have shown that patients with community-acquired CDI are younger,more likely to be female,and have fewer comorbidities compared to patients with hospital-associated CDI.Because most studies of CDI are hospitalbased,comparatively little is known about communityacquired CDI.The recent study by Chitnis has received widespread attention because it used active surveillance to capture all cases of community-acquired CDI within a large population and assessed key risk factors.The authors found that low-level healthcare exposure and proton pump inhibitor use were common among those with non-antibiotics associated,community-acquired CDI.In this commentary,we discuss the changing epidemiology of community-acquired CDI and the evidence basis for the controversial association between proton pump inhibitors and community-acquired CDI.展开更多
Plasma membrane Ca2+pumps(PMCA)play a major role in Ca2+homeostasis and signaling by extruding cellular Ca2+with high affinity.PMCA isoforms are encoded by four genes which are expressed differentially in various cell...Plasma membrane Ca2+pumps(PMCA)play a major role in Ca2+homeostasis and signaling by extruding cellular Ca2+with high affinity.PMCA isoforms are encoded by four genes which are expressed differentially in various cell types in normal and disease states.Therefore, PMCA isoform selective inhibitors would aid in delineating their role in physiology and pathophysiology.We are testing the hypothesis that extracellular domains of PMCA can be used as allosteric targets to obtain a novel class of PMCA-specific inhibitors termed caloxins. This review presents the concepts behind the invention of caloxins and our progress in this area.A section is also devoted to the applications of caloxins in literature. We anticipate that isoform-selective caloxins will aid in understanding PMCA physiology in health and disease. With strategies to develop therapeutics from bioactive peptides,caloxins may become clinically useful in car diovascular diseases,neurological disorders,retinopathy,cancer and contraception.展开更多
Background: Gastroesophageal reflux disease (GERD) is a prevalent disease in Western countries. Despite effective treatment modalities, in some patients total symptom control is not achieved in clinical practice. A cr...Background: Gastroesophageal reflux disease (GERD) is a prevalent disease in Western countries. Despite effective treatment modalities, in some patients total symptom control is not achieved in clinical practice. A cross-sectional study was designed to assess primary care practitioners’ views on the effectiveness of proton pump inhibitors (PPI) as monotherapy in the control of the most common symptoms of GERD (heartburn and regurgitation), as well as to determine the level of implementation of the “combined therapy” (PPI + alginate-antacids). Methods: A questionnaire on different aspects of the management of GERD was completed by 1491 primary care physicians. The questionnaire was composed of 11 close-ended questions with one-choice answer, with a total of 52 items, covering the main data from patients presenting with GERD. Results: Treatment with PPI alone was mostly considered insufficient for the control of GERD symptoms. The combined treatment of PPI + alginate-antacids was used for 37% and 21% of physicians for treating heart-burn and regurgitation, respectively. A better control of symptoms, an increase in the onset of action and to reduce nocturnal acid breakthrough were the most frequently argued reasons for the use of PPI + alginate-antacids. A high percentage of participants believed that treatment with PPI alone was insufficient for the control of symptoms and 39.8% of physicians reported the persistence of heartburn, 38.6% the persistence of regurgitation and 43.2% the persistence of epigastric discomfort in more than 25% of their patients treated with PPI as monotherapy. The most common schedule for the use of the antacid medication was on demand. Conclusions: Spanish primary care physicians consider that a high proportion of GERD patients continue to suffer from symptoms during PPI treatment alone. Ondemand “combined therapy” (PPI + antacid) is considered an efficient option to control reflux symptoms still troublesome in patients with PPI treatment alone.展开更多
A Geothermal Heat Pump (GHP) system is known to have enormous potential for building energy savings and the reduction of associated greenhouse gas emissions, due to its high Coefficient Of Performance (COP). The use o...A Geothermal Heat Pump (GHP) system is known to have enormous potential for building energy savings and the reduction of associated greenhouse gas emissions, due to its high Coefficient Of Performance (COP). The use of a GHP system in cold-climate regions is more attractive owing to its higher COP for heating compared to conventional heating devices, such as furnaces or boilers. Many factors, however, determine the operational performance of an existing GHP system, such as control strategy, part/full-load efficiency, the age of the system, defective parts, and whether or not regular maintenance services are provided. The omitting of any of these factors in design and operation stages could have significant impacts on the normal operation of GHP systems. Therefore, the objectives of this paper are to further investigate and study the existing GHP systems currently used in buildings located in cold-climate regions of the US, in terms of system operational performance, potential energy and energy cost savings, system cost information, the reasons for installing geothermal systems, current operating difficulties, and owner satisfaction to date. After the comprehensive investigation and in-depth analysis of 24 buildings, the results indicate that for these buildings, about 75% of the building owners are very satisfied with their GHP systems in terms of noise, cost, and indoor comfort. About 71% of the investigated GHP systems have not had serious operating difficulties, and about 85% of the respondents (building owners) would suggest this type of system to other people. Compared to the national median of energy use and energy cost of typical buildings of the same type nationwide, the overall performance of the actual GHP systems used in the cold-climate regions is slightly better, i.e. about 7.2% energy savings and 6.1% energy cost savings on average.展开更多
In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, fo...In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, forward pump scheme with reflection of 98%, backward pump scheme with reflection of 98% and bi-directional pump scheme. We show that management of thermal effects in fiber lasers will determine the efficiency and success of scaling-up efforts. In addition, we show that the most suitable scheme is the bi-directional.展开更多
Proton pump inhibitors (PPIs) are common medications within the practice of gastroenterology. These drugs, which act through the irreversible inhibition of the hydrogen/potassium pump (H+/K+-ATPase pump) in the gastri...Proton pump inhibitors (PPIs) are common medications within the practice of gastroenterology. These drugs, which act through the irreversible inhibition of the hydrogen/potassium pump (H+/K+-ATPase pump) in the gastric parietal cells, are used in the treatment of several acid-related disorders. PPIs are generally well tolerated but, through the long-term reduction of gastric acid secretion, can increase the risk of an imbalance in gut microbiota composition (i.e., dysbiosis). The gut microbiota is a complex ecosystem in which microbes coexist and interact with the human host. Indeed, the resident gut bacteria are needed for multiple vital functions, such as nutrient and drug metabolism, the production of energy, defense against pathogens, the modulation of the immune system and support of the integrity of the gut mucosal barrier. The bacteria are collected in communities that vary in density and composition within each segment of the gastrointestinal (GI) tract. Therefore, every change in the gut ecosystem has been connected to an increased susceptibility or exacerbation of various GI disorders. The aim of this review is to summarize the recently available data on PPI-related microbiota alterations in each segment of the GI tract and to analyze the possible involvement of PPIs in the pathogenesis of several specific GI diseases.展开更多
BACKGROUND Long-term use of proton pump inhibitors(PPIs)has been associated with poten-tial adverse effects,including an increased risk of gastric cancer.Despite wide-spread use awareness of these risks among physicia...BACKGROUND Long-term use of proton pump inhibitors(PPIs)has been associated with poten-tial adverse effects,including an increased risk of gastric cancer.Despite wide-spread use awareness of these risks among physicians varies considerably.Under-standing physicians’perceptions and prescribing behaviors is critical to impro-ving patient safety and promoting evidence-based practices.This study aimed to assess the level of awareness and risk perception among gastroenterologists and non-gastroenterologists regarding prolonged PPI use and its association with gastric malignancy.AIM To assess physicians’awareness of gastric cancer risk associated with long-term PPI use and compare perceptions between specialties.METHODS A cross-sectional observational study was conducted among 33 physicians(15 gastroenterologists and 18 non-gastroenterologists)in Israel.Participants com-pleted a structured questionnaire evaluating knowledge,attitudes,and prescri-bing behaviors related to PPI use.Data were analyzed using descriptive statistics and nonparametric tests to assess differences between groups and correlation patterns.Ethical approval and informed consent were obtained.RESULTS Gastroenterologists demonstrated significantly higher awareness of the potential gastric cancer risks linked to prolonged PPI use(mean awareness score:6.9±1.2)compared with non-gastroenterologists(4.1±1.3,P<0.01).Despite their awa-reness 80%of gastroenterologists reported frequent long-term prescribing.Non-parametric correlation analysis revealed associations between specialty,know-ledge level,and prescribing habits.Several misconceptions about cancer risk mechanisms were identified across specialties.CONCLUSION Physician awareness regarding gastric cancer risk of long-term PPI use remains inconsistent,especially among non-specialists,emphasizing the need for targeted educational programs and clearer prescribing guidelines.展开更多
The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to ...The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to simulate the transient internal flow field and the external performance of the pump during starting and stopping periods.The terms of accelerations due to variable speeds in the flow governing equations were analyzed in a multiple reference of frame(MRF).A transient CFD simulation was performed for a typical centrifugal pump by using ANSYS-CFX with the standard k-εturbulence model.The entire simulation process was composed of four stages:start-up,normal run,shutdown and post-shutdown.The function of rotating speed with regard to time was set by CEL language directly into the impeller domain in the pre-processor of the software to conduct variable speed simulation.The variations of the flow field in the centrifugal pump were obtained from the transient simulation.The changing laws of flow rate,head and other performance parameters over time were also analyzed and summarized.展开更多
Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matt...Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matter(AOC).However,the mechanisms underlying BCP and the amount of generated AOC deposited effectively,are still poorly understood.Therefore,we conducted a systematic study combining modern hydrochemical monitoring and a sediment trap experiment in Fuxian Lake(Yunnan,SW China),the second-deepest plateau,oligotrophic freshwater lake in China.Temperature,pH,EC(electrical conductivity),DO(dissolved O2),[HCO3^-],[Ca^2+],SIc,partial CO2(pCO2)pressure,and carbon isotopic compositions of HCO3^-(δ^13CDIc)in water from Fuxian Lake all displayed distinct seasonal and vertical variations.This was especially apparent in an inverse correlation between pCO2 and DO,indicating that variations of hydrochemistry in the lake water were mainly controlled by the metabolism of the aquatic phototrophs.Furthermore,the lowest C/N ratios and highestδ^13Corg were recorded in the trap sediments.Analyses of the C/N ratio demonstrated that the proportions of AOC ranged from 30%to 100%of all OC,indicating that AOC was an important contributor to sedimentary organic matter(OC).It was calculated that the AOC flux in Fuxian Lake was 20.43 t C km^-2 in 2017.Therefore,AOC produced by carbonate weathering and aquatic photosynthesis could potentially be a significant carbon sink and may have an important contribution to solving the lack of carbon sinks in the global carbon cycle.展开更多
文摘The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.
文摘In this paper, we propose a H∞ robust observer-based control DC motor based on a photovoltaic pumping system. Maximum power point tracking is achieved via an algorithm using Perturb and Observe method, with array voltage and current being used to generate the reference voltage which should be the PV panel’s operating voltage to get maximum available power. A Takagi-Sugeno (T-S) observer has been proposed and designed with non-measurable premise variables and the conditions of stability are given in terms of Linear Matrix Inequality (LMI). The simulation results show the effectiveness and robustness of the proposed method.
基金financially supported by the National Natural Science Foundation of China(No.51775013)the Aeronautical Science Foundation of China(No.2016ZC09007).
文摘The piston pump is the key power component in the civil aircraft hydraulic system,and the most common pump used in the aviation field is the pressure compensated variable displacement type.In this review paper,a basic introduction to the civil aircraft piston pump is presented,including the classification,structure,working principle,design features,and achievements by some research groups.Then,the future directions of the aircraft pump are reported from various perspectives.Further,the critical technologies are analyzed and summarized in detail from six thrust areas:friction couples,noise reduction,inlet boost,thermal management,fault diagnosis and health management,and mechanical seal.Finally,the challenges and limitations of the research on the aircraft pump are discussed to provide valuable insight for future scholars.
文摘BACKGROUND Proton pump inhibitors(PPIs)are widely prescribed,often without clear indications.There are conflicting data on its association with mortality risk and hepatic decompensation in cirrhotic patients.Furthermore,PPI users and PPI exposure in some studies have been poorly defined with many confounding factors.AIM To examine if PPI use increases mortality and hepatic decompensation and the impact of cumulative PPI dose exposure.METHODS Data from patients with decompensated liver cirrhosis were extracted from a hospital database between 2013 to 2017.PPI users were defined as cumulative defined daily dose(cDDD)≥28 within a landmark period,after hospitalisation for hepatic decompensation.Cox regression analysis for comparison was done after propensity score adjustment.Further risk of hepatic decompensation was analysed by Poisson regression.RESULTS Among 295 decompensated cirrhosis patients,238 were PPI users and 57 were non-users.PPI users had higher mortality compared to non-users[adjusted HR=2.10,(1.20-3.67);P=0.009].Longer PPI use with cDDD>90 was associated with higher mortality,compared to non-users[aHR=2.27,(1.10-5.14);P=0.038].PPI users had a higher incidence of hospitalization for hepatic decompensation[aRR=1.61,(1.30-2.11);P<0.001].CONCLUSION PPI use in decompensated cirrhosis is associated with increased risk of mortality and hepatic decompensation.Longer PPI exposure with cDDD>90 increases the risk of mortality.
文摘Aim: To evaluate the correlation of blood lactate and mixed venous oxygen saturation to predict outcome in off-pump coronary artery bypass grafting. Method: This is a randomized study including 30 patients. Blood lactate and mixed venous oxygen saturation were measured in 4 groups of patients—number of grafts, presence or absence of left main coronary artery disease, ejection fraction and serum creatinine. Blood samples were taken before induction, after grafting, on intensive care unit admission, 24 hours and 48 hours after surgery. The measured blood lactate and mixed venous oxygen saturation are compared to assess the outcomes in terms of duration of ventilation and intensive care unit stay. Results: The blood lactate and mixed venous oxygen saturation values increased post operatively but no statistically significant difference in three groups— number of grafts, left main coronary artery disease and ejection fraction. In serum creatinine group, the blood lactate value was found to be statistically significant after grafting in patients with creatinine <1.5 mg/dl, however, there was a significant disparity in numbers. Conclusion: Mixed venous oxygen saturation is a better predictor of morbidity than blood lactate in terms of intensive care unit stay in patients undergoing off pump coronary artery bypass grafting.
文摘Numerical simulation of diode-pumped Q-switched Nd:YAG laser leading to the generation of eye-safe signal in singly resonant Intracavity Optical Parametric Oscillator (IOPO) is presented. Starting from rate equations, the time dependent laser equations have been solved numerically, whereas the space-dependent OPO equations analytically. Our results show that 1.4 J diode laser (810 nm) pulse with 200 msec width, delivers 30 mJ Nd:YAG laser (1064 nm) pulse with 5 n-second width. This Nd:YAG laser further generates 9 mJ eye safe signal (1570 nm) pulse with 2.5 n-second width.
文摘Our study evaluated the hemodynamic performance of an axial flow blood pump surgically implanted in idealized total cavopulmonary connection(TCPC)models.This blood pump was designed to augment pressure from the inferior vena cava(IVC)to the pulmonary circulation.Two Fontan procedures with single and bilateral superior vena cava(SVC)were compared to fit the mechanical supported TCPC physiologies.Computational fluid dynamics(CFD)analyses of two Pump-TCPC models were performed in the analyses.Pressure-flow characteristics,energy efficiency,fluid streamlines,hemolysis and thrombosis analyses were implemented.Numerical simulations indicate that the pump produces pressure generations of 1 mm to 24 mm Hg for rotational speeds ranging from 2000 RPM to 5000 RPM and flow rates of 2 LPM to 4 LPM.Two surgical models incorporated with the pump were found to be insignificant in pressure augmentation and energy boost.The risk assessment of blood trauma and thrombosis generation was evaluated representatively through blood damage index(BDI),particle resident time(PRT)and relative resistant time(RRT).The hemolysis and thrombosis analyses declare the advantage of the pump supported bilateral SVC surgical scheme in balancing flow distribution and reducing the risk of endothelial cell destruction and trauma generation.
文摘Proton pump inhibitors often are prescribed in combination with clopidogrel to decrease risk of gastrointestinal bleeding after acute coronary syndrome. Clopidogrel is a prodrug that has to be metabolized in the liver to generate the active metabolite. Both medications are metabolized largely by the CYP2C19 enzyme;therefore, concerns exist that a drug-drug interaction during concomitant treatment with clopidogrel and a proton pump inhibitor may result in reduction of platelet inhibition. We have reviewed observational and randomized control studies that have evaluated the potential influence of proton pump inhibitors on the platelet inhibitory effect of clopidogrel, along with cardiovascular outcomes. We also have summarized regulatory and academic guidelines for treatment of patients in which concomitant therapy with clopidogrel and proton pump inhibitors may be indicated. Confounding issues, including differential effects of individual proton pump inhibitors on the pharmacodynamics of clopidogrel and variation in clopidogrel metabolism mediated by CYP2C19 gene polymorphisms, also are discussed.
基金Project(GC06A316) supported by the Key Technologies Research and Development Program of Heilongjiang Province, China Project(11531038) supported by the Program of the Educational Commission of Heilongjiang Province of China.
文摘Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established. In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the solar collector was employed to heating. Some of the soil heat exchangers were used to store solar energy in the soil so as to be used in next winter after this heating period; and the others were used to extract cooling energy directly in the soil by circulation pump for air conditioning in summer. After that solar energy began to be stored in the soil and ended before heating period. Three dimensional dynamic numerical simulations were built for soil and soil heat exchanger through finite element method. Simulation was done in different strata month by month. Variation and restoration of soil temperature were studied. Economy and reliability of long term SAGSHP system were revealed. It can be seen that soil temperature is about 3 ℃ higher than the original one after one year's running. It is beneficial for the system to operate for long period.
文摘Proton pump inhibitors(PPIs)are widely utilized in oncology to treat gastroeso-phageal reflux disease,peptic ulcer disease,and chemotherapy-induced mucosal injury.Emerging evidence has suggested that prolonged use of PPIs is associated with increased mortality in patients with cancer.The findings of Krishnan et al are proof of this but need to be considered cautiously due to potential confounding factors.This letter raised important methodological concerns,including con-founding by indication,reverse causality,and polypharmacy that can influence the observed association.While PPIs are important in oncology,their advantages and disadvantages should be weighed judiciously by clinicians.Future prospective studies with robust analytical approaches will be required to ascertain more definite causality.
基金Supported by Basic Science Research Program through the National Research Foundation of Korea,No.NRF-2016R1D1A1A02936964
文摘Proton pump inhibitors(PPIs) are one of the most frequently used medications for upper gastrointestinal diseases. However, a number of physicians have raised concern about the serious side effects of long-term use of PPIs, including the development of gastric cancer. Recent epidemiological studies have reported a significant association between long-term PPI intake and the risk of gastric cancer, even after successful Helicobacter pylori eradication. However, the effects of PPIs on the development of pre-malignant conditions such as atrophic gastritis or intestinal metaplasia are not fully known, suggesting the need for comprehensive and confirmative studies are needed in the future. Meanwhile,several experimental studies have demonstrated the effects of PPIs in reducing chemoresistance in gastric cancer cells by modulating the acidic microenvironment, cancer stemness and signal transducer and activator of transcription 3(STAT3) signaling pathway. The inhibitory effects of PPIs on STAT3 activity may overcome drug resistance and enhance the efficacy of conventional or targeted chemotherapeutic agents. Taken together, PPIs may"play dual role" in gastric carcinogenesis and treatment of gastric cancer.
基金Supported by National Institute of Diabetes and Digestive and Kidney Diseases T32 DK083256-0 to Freedberg DEa National Cancer Institute Career Development Award K07 CA 132892 to Abrams JA
文摘Once a nosocomial disease,Clostridium difficile infection(CDI)now appears frequently in the community in the absence of exposure to antibiotics.Prior studies have shown that patients with community-acquired CDI are younger,more likely to be female,and have fewer comorbidities compared to patients with hospital-associated CDI.Because most studies of CDI are hospitalbased,comparatively little is known about communityacquired CDI.The recent study by Chitnis has received widespread attention because it used active surveillance to capture all cases of community-acquired CDI within a large population and assessed key risk factors.The authors found that low-level healthcare exposure and proton pump inhibitor use were common among those with non-antibiotics associated,community-acquired CDI.In this commentary,we discuss the changing epidemiology of community-acquired CDI and the evidence basis for the controversial association between proton pump inhibitors and community-acquired CDI.
基金Supported by Grant-in-Aid from the Heart and Stroke Foundation of Ontario and a Doctoral Award to MMS from the Heartand Stroke Foundation of CanadaThis work is part of a pendingpatent and US Patent 7091174B2
文摘Plasma membrane Ca2+pumps(PMCA)play a major role in Ca2+homeostasis and signaling by extruding cellular Ca2+with high affinity.PMCA isoforms are encoded by four genes which are expressed differentially in various cell types in normal and disease states.Therefore, PMCA isoform selective inhibitors would aid in delineating their role in physiology and pathophysiology.We are testing the hypothesis that extracellular domains of PMCA can be used as allosteric targets to obtain a novel class of PMCA-specific inhibitors termed caloxins. This review presents the concepts behind the invention of caloxins and our progress in this area.A section is also devoted to the applications of caloxins in literature. We anticipate that isoform-selective caloxins will aid in understanding PMCA physiology in health and disease. With strategies to develop therapeutics from bioactive peptides,caloxins may become clinically useful in car diovascular diseases,neurological disorders,retinopathy,cancer and contraception.
文摘Background: Gastroesophageal reflux disease (GERD) is a prevalent disease in Western countries. Despite effective treatment modalities, in some patients total symptom control is not achieved in clinical practice. A cross-sectional study was designed to assess primary care practitioners’ views on the effectiveness of proton pump inhibitors (PPI) as monotherapy in the control of the most common symptoms of GERD (heartburn and regurgitation), as well as to determine the level of implementation of the “combined therapy” (PPI + alginate-antacids). Methods: A questionnaire on different aspects of the management of GERD was completed by 1491 primary care physicians. The questionnaire was composed of 11 close-ended questions with one-choice answer, with a total of 52 items, covering the main data from patients presenting with GERD. Results: Treatment with PPI alone was mostly considered insufficient for the control of GERD symptoms. The combined treatment of PPI + alginate-antacids was used for 37% and 21% of physicians for treating heart-burn and regurgitation, respectively. A better control of symptoms, an increase in the onset of action and to reduce nocturnal acid breakthrough were the most frequently argued reasons for the use of PPI + alginate-antacids. A high percentage of participants believed that treatment with PPI alone was insufficient for the control of symptoms and 39.8% of physicians reported the persistence of heartburn, 38.6% the persistence of regurgitation and 43.2% the persistence of epigastric discomfort in more than 25% of their patients treated with PPI as monotherapy. The most common schedule for the use of the antacid medication was on demand. Conclusions: Spanish primary care physicians consider that a high proportion of GERD patients continue to suffer from symptoms during PPI treatment alone. Ondemand “combined therapy” (PPI + antacid) is considered an efficient option to control reflux symptoms still troublesome in patients with PPI treatment alone.
文摘A Geothermal Heat Pump (GHP) system is known to have enormous potential for building energy savings and the reduction of associated greenhouse gas emissions, due to its high Coefficient Of Performance (COP). The use of a GHP system in cold-climate regions is more attractive owing to its higher COP for heating compared to conventional heating devices, such as furnaces or boilers. Many factors, however, determine the operational performance of an existing GHP system, such as control strategy, part/full-load efficiency, the age of the system, defective parts, and whether or not regular maintenance services are provided. The omitting of any of these factors in design and operation stages could have significant impacts on the normal operation of GHP systems. Therefore, the objectives of this paper are to further investigate and study the existing GHP systems currently used in buildings located in cold-climate regions of the US, in terms of system operational performance, potential energy and energy cost savings, system cost information, the reasons for installing geothermal systems, current operating difficulties, and owner satisfaction to date. After the comprehensive investigation and in-depth analysis of 24 buildings, the results indicate that for these buildings, about 75% of the building owners are very satisfied with their GHP systems in terms of noise, cost, and indoor comfort. About 71% of the investigated GHP systems have not had serious operating difficulties, and about 85% of the respondents (building owners) would suggest this type of system to other people. Compared to the national median of energy use and energy cost of typical buildings of the same type nationwide, the overall performance of the actual GHP systems used in the cold-climate regions is slightly better, i.e. about 7.2% energy savings and 6.1% energy cost savings on average.
文摘In this paper, we present a study of thermal, average power scaling, change in index of refraction and stress in photonic crystal fiber lasers with different pump schemes: forward pump scheme, backward pump scheme, forward pump scheme with reflection of 98%, backward pump scheme with reflection of 98% and bi-directional pump scheme. We show that management of thermal effects in fiber lasers will determine the efficiency and success of scaling-up efforts. In addition, we show that the most suitable scheme is the bi-directional.
文摘Proton pump inhibitors (PPIs) are common medications within the practice of gastroenterology. These drugs, which act through the irreversible inhibition of the hydrogen/potassium pump (H+/K+-ATPase pump) in the gastric parietal cells, are used in the treatment of several acid-related disorders. PPIs are generally well tolerated but, through the long-term reduction of gastric acid secretion, can increase the risk of an imbalance in gut microbiota composition (i.e., dysbiosis). The gut microbiota is a complex ecosystem in which microbes coexist and interact with the human host. Indeed, the resident gut bacteria are needed for multiple vital functions, such as nutrient and drug metabolism, the production of energy, defense against pathogens, the modulation of the immune system and support of the integrity of the gut mucosal barrier. The bacteria are collected in communities that vary in density and composition within each segment of the gastrointestinal (GI) tract. Therefore, every change in the gut ecosystem has been connected to an increased susceptibility or exacerbation of various GI disorders. The aim of this review is to summarize the recently available data on PPI-related microbiota alterations in each segment of the GI tract and to analyze the possible involvement of PPIs in the pathogenesis of several specific GI diseases.
文摘BACKGROUND Long-term use of proton pump inhibitors(PPIs)has been associated with poten-tial adverse effects,including an increased risk of gastric cancer.Despite wide-spread use awareness of these risks among physicians varies considerably.Under-standing physicians’perceptions and prescribing behaviors is critical to impro-ving patient safety and promoting evidence-based practices.This study aimed to assess the level of awareness and risk perception among gastroenterologists and non-gastroenterologists regarding prolonged PPI use and its association with gastric malignancy.AIM To assess physicians’awareness of gastric cancer risk associated with long-term PPI use and compare perceptions between specialties.METHODS A cross-sectional observational study was conducted among 33 physicians(15 gastroenterologists and 18 non-gastroenterologists)in Israel.Participants com-pleted a structured questionnaire evaluating knowledge,attitudes,and prescri-bing behaviors related to PPI use.Data were analyzed using descriptive statistics and nonparametric tests to assess differences between groups and correlation patterns.Ethical approval and informed consent were obtained.RESULTS Gastroenterologists demonstrated significantly higher awareness of the potential gastric cancer risks linked to prolonged PPI use(mean awareness score:6.9±1.2)compared with non-gastroenterologists(4.1±1.3,P<0.01).Despite their awa-reness 80%of gastroenterologists reported frequent long-term prescribing.Non-parametric correlation analysis revealed associations between specialty,know-ledge level,and prescribing habits.Several misconceptions about cancer risk mechanisms were identified across specialties.CONCLUSION Physician awareness regarding gastric cancer risk of long-term PPI use remains inconsistent,especially among non-specialists,emphasizing the need for targeted educational programs and clearer prescribing guidelines.
文摘The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to simulate the transient internal flow field and the external performance of the pump during starting and stopping periods.The terms of accelerations due to variable speeds in the flow governing equations were analyzed in a multiple reference of frame(MRF).A transient CFD simulation was performed for a typical centrifugal pump by using ANSYS-CFX with the standard k-εturbulence model.The entire simulation process was composed of four stages:start-up,normal run,shutdown and post-shutdown.The function of rotating speed with regard to time was set by CEL language directly into the impeller domain in the pre-processor of the software to conduct variable speed simulation.The variations of the flow field in the centrifugal pump were obtained from the transient simulation.The changing laws of flow rate,head and other performance parameters over time were also analyzed and summarized.
基金supported by the National Natural Science Foundation of China (Nos. 41430753, U1612441)
文摘Biological carbon pumping(BCP)is a key process in which dissolved inorganic carbon in terrestrial aquatic ecosystems is utilized by aquatic autotrophs for photosynthesis and transformed into autochthonous organic matter(AOC).However,the mechanisms underlying BCP and the amount of generated AOC deposited effectively,are still poorly understood.Therefore,we conducted a systematic study combining modern hydrochemical monitoring and a sediment trap experiment in Fuxian Lake(Yunnan,SW China),the second-deepest plateau,oligotrophic freshwater lake in China.Temperature,pH,EC(electrical conductivity),DO(dissolved O2),[HCO3^-],[Ca^2+],SIc,partial CO2(pCO2)pressure,and carbon isotopic compositions of HCO3^-(δ^13CDIc)in water from Fuxian Lake all displayed distinct seasonal and vertical variations.This was especially apparent in an inverse correlation between pCO2 and DO,indicating that variations of hydrochemistry in the lake water were mainly controlled by the metabolism of the aquatic phototrophs.Furthermore,the lowest C/N ratios and highestδ^13Corg were recorded in the trap sediments.Analyses of the C/N ratio demonstrated that the proportions of AOC ranged from 30%to 100%of all OC,indicating that AOC was an important contributor to sedimentary organic matter(OC).It was calculated that the AOC flux in Fuxian Lake was 20.43 t C km^-2 in 2017.Therefore,AOC produced by carbonate weathering and aquatic photosynthesis could potentially be a significant carbon sink and may have an important contribution to solving the lack of carbon sinks in the global carbon cycle.
