In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pu...In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pumping voltage and PWM ratio is derived and a new digital control method to restrain the pumping voltage by changing PWM ratio is put forward. Because the capacitance is decreased effectively, the volume of controller is reduced and the performance to price ratio is improved. The results of computer simulation and experiment proved that this method is feasible and valid.展开更多
A control strategy of switched reluctance motor (SRM)for electric vehicle applications is proposed. In electric vehicle application, the switched reluctance motor is a good choice with its flexible control method, com...A control strategy of switched reluctance motor (SRM)for electric vehicle applications is proposed. In electric vehicle application, the switched reluctance motor is a good choice with its flexible control method, compactness, robustness, high efficiency and high starting torque. In this paper, the control strategy of motoring and regenerative braking for electric vehicle application is presented. Computer simulations are employed to analyze the steady state behavior of SRM propulsion system. Experimental results in electric motorcycle are provided to demonstrate the validity of SRM propulsion system.展开更多
AIM: The GFAP was traditionally considered to be a biomarker for neural gila (mainly astrocytes and nonmyelinating Schwann cells). Genetically, a 2.2-kb human GFAP promoter has been successfully used to target astr...AIM: The GFAP was traditionally considered to be a biomarker for neural gila (mainly astrocytes and nonmyelinating Schwann cells). Genetically, a 2.2-kb human GFAP promoter has been successfully used to target astrocytes in vitro and in vivo. More recently, GFAP was also established as one of the several makers for identifying hepatic stellate cells (HSC). In this project, possible application of the same 2.2-kb human GFAP promoter for targeting HSC was investigated. METHODS: The GFAP-lacZ transgene was transfected into various cell lines (HSC, hepatocyte, and other nonHSC cell types). The transgene expression specificity was determined by X-gal staining of the β-galactosidase activity. And the responsiveness of the transgene was tested with a typical pro-fibrotic cytokine TGF-β1. The expression of endogenous GFAP gene was assessed by real-time RT-PCR, providing a reference for the transgene expression. RESULTS: The results demonstrated for the first time that the 2.2 kb hGFAP promoter was not only capable of directing HSC-specific expression, but also responding to a known pro-fibrogenic cytokine TGF-β1 by upregulation in a doseand time-dependent manner, similar to the endogenous GFAP. CONCLUSION: In conclusion, these findings suggested novel utilities for using the GFAP promoter to specifically manipulate HSC for therapeutic purpose.展开更多
The rapid development of urban rail transit brings convenience to the public,but its huge energy consumption problem cannot be ignored.A microgrid composed of photovoltaic power generation unit,regenerative braking en...The rapid development of urban rail transit brings convenience to the public,but its huge energy consumption problem cannot be ignored.A microgrid composed of photovoltaic power generation unit,regenerative braking energy feedback unit and battery energy storage unit is proposed,which provides green power for the station.In order to suppress the fluctuation of photovoltaic power generation and the intermittence of regenerative braking feedback energy,the energy management mode of microgrid is designed according to the illumination situation,braking energy feedback situation,battery state of charge and so on.In addition,a coordination control method based on virtual synchronous generator(VSG)is proposed to realize smooth switching among modes.Finally,the proposed energy management and coordination control method for elevated station microgrid is verified by Matlab/Simulink.The results show that the elevated station microgrid can operate safely and reliably under various energy management modes and realize smooth switching among modes.展开更多
AIM: To study the relationship between the patterns of postprandial peristalsis and transduodenal bolus transport in healthy subjects. METHODS: Synchronous recording of chyme transport and peristaltic activity was per...AIM: To study the relationship between the patterns of postprandial peristalsis and transduodenal bolus transport in healthy subjects. METHODS: Synchronous recording of chyme transport and peristaltic activity was performed during the fasting state and after administration of a test meal using a special catheter device with cascade configuration of impedance electrodes and solid-state pressure transducers. The catheter was placed into the duodenum, where the f irst channel was located in the f irst part of the duodenum and the last channel at the duodenojejunal junction. After identif ication of previously def ined chyme transport patterns the associated peristaltic patterns were analyzed. RESULTS: The interdigestive phase 3 complex was reliably recorded with both techniques. Of 497 analyzed impedance bolus transport events, 110 (22%) were short-spanned propulsive, 307 (62%) long-spanned propulsive, 70 (14%) complex propulsive, and 10 (2%) retrograde transport. Short-spanned chyme transports were predominantly associated with stationary or propagated contractions propagated over short distance. Long-spanned and complex chyme transports were predominantly associated with propulsive peristaltic patterns, which were frequently complex and comprised multiple contractions. Propagated double wave contraction, propagated contraction with a clustered contraction, and propagated cluster of contractions have been identif ied to be an integralted part of a peristaltic sequence in human duodenum. CONCLUSION: Combined impedancometry and manometry improves the analysis of the peristaltic patterns that are associated with postprandial transduodenal chymetransport. Postprandial transduodenal bolus transport is regulated by propulsive peristaltic patterns, which are frequently complex but well organized. This f inding should be taken into consideration in the analysis of intestinal motility studies.展开更多
AIM: To investigate the effects of mangiferin on gas- trointestinal transit (GIT) in normal and constipated mice, together with the possible mechanism.METHODS: Intragastrically-administered charcoal mealwas used t...AIM: To investigate the effects of mangiferin on gas- trointestinal transit (GIT) in normal and constipated mice, together with the possible mechanism.METHODS: Intragastrically-administered charcoal mealwas used to measure GIT in overnight starved Swiss mice. In the first experiments, mangiferin (3 mg/kg, 10 mg/kg, 30 mg/kg, and 100 mg/kg, po) or tegaserod (1 mg/kg, ip) were administered 30 min before the char- coal meal to study their effects on normal transit. In the second series, mangiferin (30 mg/kg) was tested on delayed GIT induced by several different pharma- cological agonists (morphine, clonidine, capsaicin) or antagonists (ondansetron, verapamil, and atropine) whereas in the third series, mangiferin (30 mg/kg, 100 mg/kg and 300 mg/kg) or tegaserod (1 mg/kg) were tested on 6 h fecal pellets outputted by freely fed mice. The ratio of wet to dry weight was calculated and used as a marker of fecal water content. RESULTS: Mangiferin administered orally significantly (P 〈 0.05) accelerated GIT at 30 mg/kg and 100 mg/kg (89% and 93%, respectively), similarly to 5-hydroxytrypta- mine4 (5-H%) agonist tegaserod (81%) when compared to vehicle-treated control (63%). Co-administered man- giferin (30 mg/kg) totally reversed the inhibitory effect of opioid agonist morphine, 5-HT3-receptor antagonist ondansetron and transient receptor potential vanilloid-1 receptor agonist capsaicin on GIT, but only to a partial extent with the GIT-delay induced by ~2-adrenoceptor agonist clonidine, and calcium antagonist verapamil. However, co-administered atropine completely blocked the stimulant effect of mangiferin on GIT, suggesting the involvement of muscarinic acetylcholine receptor activation. Although mangiferin significantly enhanced the 6 h fecal output at higher doses (245.5±10.43 mg vs 161.9±10.82 mg and 227.1±20.11 mg vs 161.9±10.82 mg of vehicle-treated control, at 30 and 100 mg/ kg, P 〈 0.05, respectively), the effect of tegaserod was more potent (297.4±7.42 mg vs 161.9±10.82 mg of vehicle-treated control, P 〈 0.05). Unlike tegaserod, which showed an enhanced water content in fecal pel- lets (59.20%±1.09% vs 51.44%±1.19% of control, P 〈 0.05), mangiferin evidenced no such effect, indi-cating that it has only a motor and not a secretomotor effect. CONCLUSION: Our data indicate the prokinetic action of mangiferin. It can stimulate the normal GIT and also overcome the drug-induced transit delay, via a choliner- gic physiological mechanism.展开更多
As the pneumatic artificial muscle (PAM) has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in...As the pneumatic artificial muscle (PAM) has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in robotics. In this paper, a kind of musculoskeletal leg mechanism driven by PAMs is presented, which has three joints driven by four PAMs. The jumping movement is divided into three phases. The forward and inverse kinematics of the leg mechanism in different jumping phases is derived. Considering the ground reaction force between feet and environment, the dynamic in different jumping phases is analyzed by Lagrange method, then the relationship between PAM driving force and the joints angular displacement, angular velocity, angular acceleration during one jumping cycle is obtained, which will lay a foundatiori for the jumping experiment of the musculo- skeletal lez mechanism.展开更多
To predict the flow evolution of fish swimming problems,a flow solver based on the immersed boundary lattice Boltzmann method is developed.A flexible iterative algorithm based on the framework of implicit boundary for...To predict the flow evolution of fish swimming problems,a flow solver based on the immersed boundary lattice Boltzmann method is developed.A flexible iterative algorithm based on the framework of implicit boundary force correction is used to save the computational cost and memory,and the momentum forcing is described by a simple direct force formula without complicated integral calculation when the velocity correction at the boundary node is determined.With the presented flow solver,the hydrodynamic interaction between the fish-induced dynamic stall vortices and the incoming vortices in unsteady flow is analyzed.Numerical simulation results unveil the mechanism of fish exploiting vortices to enhance their own hydrodynamic performances.The superior swimming performances originate from the relative movement between the“merged vortex”and the locomotion of the fishtail,which is controlled by the phase difference.Formation conditions of the“merged vortex”become the key factor for fish to exploit vortices to improve their swimming performance.We further discuss the effect of the principal components of locomotion.From the results,we conclude that lateral translation plays a crucial role in propulsion while body undulation in tandem with rotation and head motion reduce the locomotor cost.展开更多
Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF in older adults, and is increasing in preva- lence as the population ages. Furthermore, HFpEF is increasing out of proporti...Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF in older adults, and is increasing in preva- lence as the population ages. Furthermore, HFpEF is increasing out of proportion to HF with reduced EF (HFrEF), and its prognosis is worsening while that of HFrEF is improving. Despite the importance of HFpEF, our understanding of its pathophysiology is incomplete, and optimal treatment remains largely undefined. A cardinal feature of HFpEF is reduced exercise tolerance, which correlates with symptoms as well as reduced quality of life. The traditional concepts of exercise limitations have focused on central dysfimction related to poor cardiac pump function. However, the mechanisms are not exclusive to the heart and lungs, and the understanding of the pathophysiology of this dis- ease has evolved. Substantial attention has focused on defining the central versus peripheral mechanisms underlying the reduced functional capacity and exercise tolerance among patients with HF. In fact, physical training can improve exercise tolerance via peripheral adaptive mechanisms even in the absence of favorable central hemodynamic function. In addition, the drug trials performed to date in HFpEF that have focused on influencing cardiovascular function have not improved exercise capacity. This suggests that peripheral limitations may play a significant role in HF limiting exercise tolerance, a hallmark feature of HFpEF.展开更多
The application of human induced oxygen consumption and carbon emission theory in urban region was summed up and on this base a new model of urban carbon and oxygen balance (UCOB) was constructed by calculating the ca...The application of human induced oxygen consumption and carbon emission theory in urban region was summed up and on this base a new model of urban carbon and oxygen balance (UCOB) was constructed by calculating the carbon and oxygen fluxes. The purpose was to highlight the role of vegetation in urban ecosystems and evaluate the effects of various human activities on urban annual oxygen consumption and carbon emission. Hopefully,the model would be helpful in theory to keep the regional balance of carbon and oxygen,and provide guidance and support for urban vegetation planning in the future. To test the UCOB model,the Jimei District of Xiamen City,Fujian Province,China,a very typical urban region,was selected as a case study. The results turn out that Jimei′s vegetation service in oxygen emission and carbon sequestration could not meet the demand of the urban population,and more than 31.49 times of vegetation area should be added to meet the whole oxygen consumption in Jimei while 9.60 times of vegetation area are needed to meet the carbon sequestration targets. The results show that the new UCOB model is of a great potential to be applied to quantitative planning of urban vegetation and regional eco-compensation mechanisms.展开更多
AIM: To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS: A noninvasive gastric motility measure- men...AIM: To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS: A noninvasive gastric motility measure- ment method combining electrogastrograrn (EGG) and impedance gastric motility (IGM) test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia (FD) and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients (mean age 40.9±9.7 years) and 40 healthy volun- teers (mean age 30.9±7.9 years) were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients (mean age 50.5±13.0 years) and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS: There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency (PNF) 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups (PNF 70.4:1:25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05). The EGG rhythm of the gastritis patients returned to normal (frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 :t: 0.19 one wk after treatment, P 〈 0.05) after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION: The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.展开更多
The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compo...The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.展开更多
The literature shows that improvements in cognitive performance may be observed following an acute bout of exercise. However, evidence in support of the biological mechanisms of this effect is still limited. Findings ...The literature shows that improvements in cognitive performance may be observed following an acute bout of exercise. However, evidence in support of the biological mechanisms of this effect is still limited. Findings from both rodent and human studies suggest brain-derived neu- rotrophic factor (BDNF) as a potential mechanism of the effect of acute exercise on memory. The molecular properties of BDNF allow this protein to be assessed in the periphery (pBDNF) (i.e., blood serum, blood plasma), making measurements of acute exercise-induced changes in BDNF concentration relatively accessible. Studies exploring the acute exercise--pBDNF--cognitive performance relationship have had mixed findings, but this may be more reflective of methodological differences between studies than it is a statement about the role of BDNE For example, significant associations have been observed between acute exercise-induced changes in pBDNF concentration and cognitive performance in studies assessing memory, and non-significant associations have been found in studies assessing non-memory cognitive domains. Three suggestions are made for future research aimed at understanding the role of BDNF as a biological mechanism of this relationship: 1) Assessments of cognitive performance may benefit from a focus on various types of memory (e.g., relational, spatial, long-term); 2) More finegrained measurements of pBDNF will allow for the assessment of concentrations of specific isoforms of the BDNF protein (i.e., immature, mature); 3) Statistical techniques designed to test the mediating role of pBDNF in the acute exercise-cognitive performance relationship should be utilized in order to make causal inferences.展开更多
Reduced blood flow is the principle pathophysiologic event in acute ischernic stroke.Hence,flow augmentation is the most important goal in stroke management.Improvement of cerebral blood flow can be accomplished by pr...Reduced blood flow is the principle pathophysiologic event in acute ischernic stroke.Hence,flow augmentation is the most important goal in stroke management.Improvement of cerebral blood flow can be accomplished by proximal arterial recanalization or by other systemic approaches.Diastolic counterpulsation is a non-invasive method to improve the perfusion of heart,kidneys and brain.This review summarizes the history,possible mechanism and the role of external counterpulsation in ischemic stroke.展开更多
We used a potent and specific monoclonal antibody to somatostatin to test the physiologic inhibitory role of the tetradecapeptide somatostatin on pancreatic secretion.Somatostatin immunoneutralization increased both t...We used a potent and specific monoclonal antibody to somatostatin to test the physiologic inhibitory role of the tetradecapeptide somatostatin on pancreatic secretion.Somatostatin immunoneutralization increased both the total amylase and volume of pancreatic secretion.Cholecystokinin-A receptor antagonism abolished the stimulatory effect of somatostatin immunoneutralization.We conclude that somatostatin tonically inhibits pancreatic secretion in fasted rats via inhibition of the release or action of cholecystokinin.Furthermore,the source of these peptides is likely islet delta cells and intrapancreatic neurons,respectively.展开更多
The phenomenon described here has no scientific title, but occurs frequently in daily living, from science to philosophy, religion, and medicine. In every field of human endeavor, when a view is expressed, sharp and p...The phenomenon described here has no scientific title, but occurs frequently in daily living, from science to philosophy, religion, and medicine. In every field of human endeavor, when a view is expressed, sharp and profound differences of opinion ensue. Initially, we coin this phenomenon as "understanding blindness" or "mind's awareness." Thereafter, we decide to refer to it as "mind blindness," a concept introduced to science by Professor Simon Baron-Cohen, who coins it for a cognitive disorder associated with autism, Asperger's syndrome, and schizophrenia. Baron-Cohen's usage has subsequently been extended to dementia, bi-polar disorders, antisocial personality disorders, and even normal aging. In our view, definition and identification of "mind blindness" in philosophy, religion, science, medicine, and at end-of-life care can help mankind to better understand mechanisms of human behavior, and the causes of conflicts, controversies, contradictions, and sharp differences of opinion in human life, and even to solve some of them.展开更多
Growing literature has demonstrated that exercise may be an effective prevention and treatment option for drug addiction. In the past few years, many studies have suggested that there were sex differences in all phase...Growing literature has demonstrated that exercise may be an effective prevention and treatment option for drug addiction. In the past few years, many studies have suggested that there were sex differences in all phases of drug addiction. However, very limited research has investigated sex differences in the effectiveness of exercise intervention in drug addiction and rehabilitation. In this mini review, we summarize the effect of sex on the results of using exercise to prevent and treat drug addiction. The studies we consider span various animal models and use multiple types of exercise to examine the effectiveness of exercise on the neurobiological mechanism of exercise rehabilitation. We believe that exercise as an adjuvant intervention strategy can be applied better in drug addiction prevention and recovery. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.展开更多
In this work, the stability of an endoreversible Curzon-Ahlbom engine is analyzed, using Van der Waals gas as a working substance and the corresponding efficiency for this engine working at temperatures withinthe maxi...In this work, the stability of an endoreversible Curzon-Ahlbom engine is analyzed, using Van der Waals gas as a working substance and the corresponding efficiency for this engine working at temperatures withinthe maximum ecological regime. By mean s of a local stability analysis we find that a critical point of an almost linear system is stable andanalytically expressed in eigenvalues. After an arbitrarily small perturbation, the system state exponentially decays to a critical point, with either of two characteristic relaxation times, which are a function of the thermal conductance (a), heat capacity (C) and T=T2/T1. The behavior of relaxation times and solution of the systems are qualitatively shown by sketching its phase portrait, which results susceptible to operating regimes, i.e., the eigenvectors in the maximum ecological regime have a clockwise rotation with respect to the eigenvectors in the regime of maximumpower. Finally, it has to observe that afterto λvw = 1, approximation,ηVWE=4^-3ηC is obtained, where ηVWE is the Van der Waals efficiency atrnaximum ecological regime and r/c is Carnot's efficiency. Finally, it discussed the local stability and steady state of the energetic properties of the endoreversible engine.展开更多
文摘In order to restrain the high pumping voltage of braking procedure which is harmful to the system of electric armored vehicle. Based on the analysis of pumping voltage of the braking procedure, the relation between pumping voltage and PWM ratio is derived and a new digital control method to restrain the pumping voltage by changing PWM ratio is put forward. Because the capacitance is decreased effectively, the volume of controller is reduced and the performance to price ratio is improved. The results of computer simulation and experiment proved that this method is feasible and valid.
文摘A control strategy of switched reluctance motor (SRM)for electric vehicle applications is proposed. In electric vehicle application, the switched reluctance motor is a good choice with its flexible control method, compactness, robustness, high efficiency and high starting torque. In this paper, the control strategy of motoring and regenerative braking for electric vehicle application is presented. Computer simulations are employed to analyze the steady state behavior of SRM propulsion system. Experimental results in electric motorcycle are provided to demonstrate the validity of SRM propulsion system.
基金Supported by the Biomedical Research Councilthe Institute of Bioengineering and Nanotechnology,the Republic of Singapore
文摘AIM: The GFAP was traditionally considered to be a biomarker for neural gila (mainly astrocytes and nonmyelinating Schwann cells). Genetically, a 2.2-kb human GFAP promoter has been successfully used to target astrocytes in vitro and in vivo. More recently, GFAP was also established as one of the several makers for identifying hepatic stellate cells (HSC). In this project, possible application of the same 2.2-kb human GFAP promoter for targeting HSC was investigated. METHODS: The GFAP-lacZ transgene was transfected into various cell lines (HSC, hepatocyte, and other nonHSC cell types). The transgene expression specificity was determined by X-gal staining of the β-galactosidase activity. And the responsiveness of the transgene was tested with a typical pro-fibrotic cytokine TGF-β1. The expression of endogenous GFAP gene was assessed by real-time RT-PCR, providing a reference for the transgene expression. RESULTS: The results demonstrated for the first time that the 2.2 kb hGFAP promoter was not only capable of directing HSC-specific expression, but also responding to a known pro-fibrogenic cytokine TGF-β1 by upregulation in a doseand time-dependent manner, similar to the endogenous GFAP. CONCLUSION: In conclusion, these findings suggested novel utilities for using the GFAP promoter to specifically manipulate HSC for therapeutic purpose.
基金National Natural Science Foundation of China(No.51367010)Science and Technology Program of Gansu Province(No.17JR5RA083)Program for Excellent Team of Scientific Research in Lanzhou Jiaotong University(No.201701)
文摘The rapid development of urban rail transit brings convenience to the public,but its huge energy consumption problem cannot be ignored.A microgrid composed of photovoltaic power generation unit,regenerative braking energy feedback unit and battery energy storage unit is proposed,which provides green power for the station.In order to suppress the fluctuation of photovoltaic power generation and the intermittence of regenerative braking feedback energy,the energy management mode of microgrid is designed according to the illumination situation,braking energy feedback situation,battery state of charge and so on.In addition,a coordination control method based on virtual synchronous generator(VSG)is proposed to realize smooth switching among modes.Finally,the proposed energy management and coordination control method for elevated station microgrid is verified by Matlab/Simulink.The results show that the elevated station microgrid can operate safely and reliably under various energy management modes and realize smooth switching among modes.
基金Supported by a grant of the University of Aachen "START-Project"
文摘AIM: To study the relationship between the patterns of postprandial peristalsis and transduodenal bolus transport in healthy subjects. METHODS: Synchronous recording of chyme transport and peristaltic activity was performed during the fasting state and after administration of a test meal using a special catheter device with cascade configuration of impedance electrodes and solid-state pressure transducers. The catheter was placed into the duodenum, where the f irst channel was located in the f irst part of the duodenum and the last channel at the duodenojejunal junction. After identif ication of previously def ined chyme transport patterns the associated peristaltic patterns were analyzed. RESULTS: The interdigestive phase 3 complex was reliably recorded with both techniques. Of 497 analyzed impedance bolus transport events, 110 (22%) were short-spanned propulsive, 307 (62%) long-spanned propulsive, 70 (14%) complex propulsive, and 10 (2%) retrograde transport. Short-spanned chyme transports were predominantly associated with stationary or propagated contractions propagated over short distance. Long-spanned and complex chyme transports were predominantly associated with propulsive peristaltic patterns, which were frequently complex and comprised multiple contractions. Propagated double wave contraction, propagated contraction with a clustered contraction, and propagated cluster of contractions have been identif ied to be an integralted part of a peristaltic sequence in human duodenum. CONCLUSION: Combined impedancometry and manometry improves the analysis of the peristaltic patterns that are associated with postprandial transduodenal chymetransport. Postprandial transduodenal bolus transport is regulated by propulsive peristaltic patterns, which are frequently complex but well organized. This f inding should be taken into consideration in the analysis of intestinal motility studies.
基金Supported by National Council of Technological and Scientific Development (CNPq)Ceará Foundation for the Support of Scientific and Technological Development of the Ceará State(FUNCAP),Brazil
文摘AIM: To investigate the effects of mangiferin on gas- trointestinal transit (GIT) in normal and constipated mice, together with the possible mechanism.METHODS: Intragastrically-administered charcoal mealwas used to measure GIT in overnight starved Swiss mice. In the first experiments, mangiferin (3 mg/kg, 10 mg/kg, 30 mg/kg, and 100 mg/kg, po) or tegaserod (1 mg/kg, ip) were administered 30 min before the char- coal meal to study their effects on normal transit. In the second series, mangiferin (30 mg/kg) was tested on delayed GIT induced by several different pharma- cological agonists (morphine, clonidine, capsaicin) or antagonists (ondansetron, verapamil, and atropine) whereas in the third series, mangiferin (30 mg/kg, 100 mg/kg and 300 mg/kg) or tegaserod (1 mg/kg) were tested on 6 h fecal pellets outputted by freely fed mice. The ratio of wet to dry weight was calculated and used as a marker of fecal water content. RESULTS: Mangiferin administered orally significantly (P 〈 0.05) accelerated GIT at 30 mg/kg and 100 mg/kg (89% and 93%, respectively), similarly to 5-hydroxytrypta- mine4 (5-H%) agonist tegaserod (81%) when compared to vehicle-treated control (63%). Co-administered man- giferin (30 mg/kg) totally reversed the inhibitory effect of opioid agonist morphine, 5-HT3-receptor antagonist ondansetron and transient receptor potential vanilloid-1 receptor agonist capsaicin on GIT, but only to a partial extent with the GIT-delay induced by ~2-adrenoceptor agonist clonidine, and calcium antagonist verapamil. However, co-administered atropine completely blocked the stimulant effect of mangiferin on GIT, suggesting the involvement of muscarinic acetylcholine receptor activation. Although mangiferin significantly enhanced the 6 h fecal output at higher doses (245.5±10.43 mg vs 161.9±10.82 mg and 227.1±20.11 mg vs 161.9±10.82 mg of vehicle-treated control, at 30 and 100 mg/ kg, P 〈 0.05, respectively), the effect of tegaserod was more potent (297.4±7.42 mg vs 161.9±10.82 mg of vehicle-treated control, P 〈 0.05). Unlike tegaserod, which showed an enhanced water content in fecal pel- lets (59.20%±1.09% vs 51.44%±1.19% of control, P 〈 0.05), mangiferin evidenced no such effect, indi-cating that it has only a motor and not a secretomotor effect. CONCLUSION: Our data indicate the prokinetic action of mangiferin. It can stimulate the normal GIT and also overcome the drug-induced transit delay, via a choliner- gic physiological mechanism.
基金Supported by the National Natural Science Foundation of China(No.51375289)Shanghai Municipal National Natural Science Foundation of China(No.13ZR1415500)Innovation Fund of Shanghai Education Commission(No.13YZ020)
文摘As the pneumatic artificial muscle (PAM) has flexibility properties similar to biological muscle which is widely used in robotics as one kind of actuators, the bionic mechanism driven by PAMs be- comes a hot spot in robotics. In this paper, a kind of musculoskeletal leg mechanism driven by PAMs is presented, which has three joints driven by four PAMs. The jumping movement is divided into three phases. The forward and inverse kinematics of the leg mechanism in different jumping phases is derived. Considering the ground reaction force between feet and environment, the dynamic in different jumping phases is analyzed by Lagrange method, then the relationship between PAM driving force and the joints angular displacement, angular velocity, angular acceleration during one jumping cycle is obtained, which will lay a foundatiori for the jumping experiment of the musculo- skeletal lez mechanism.
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘To predict the flow evolution of fish swimming problems,a flow solver based on the immersed boundary lattice Boltzmann method is developed.A flexible iterative algorithm based on the framework of implicit boundary force correction is used to save the computational cost and memory,and the momentum forcing is described by a simple direct force formula without complicated integral calculation when the velocity correction at the boundary node is determined.With the presented flow solver,the hydrodynamic interaction between the fish-induced dynamic stall vortices and the incoming vortices in unsteady flow is analyzed.Numerical simulation results unveil the mechanism of fish exploiting vortices to enhance their own hydrodynamic performances.The superior swimming performances originate from the relative movement between the“merged vortex”and the locomotion of the fishtail,which is controlled by the phase difference.Formation conditions of the“merged vortex”become the key factor for fish to exploit vortices to improve their swimming performance.We further discuss the effect of the principal components of locomotion.From the results,we conclude that lateral translation plays a crucial role in propulsion while body undulation in tandem with rotation and head motion reduce the locomotor cost.
文摘Heart failure (HF) with preserved ejection fraction (HFpEF) is the most common form of HF in older adults, and is increasing in preva- lence as the population ages. Furthermore, HFpEF is increasing out of proportion to HF with reduced EF (HFrEF), and its prognosis is worsening while that of HFrEF is improving. Despite the importance of HFpEF, our understanding of its pathophysiology is incomplete, and optimal treatment remains largely undefined. A cardinal feature of HFpEF is reduced exercise tolerance, which correlates with symptoms as well as reduced quality of life. The traditional concepts of exercise limitations have focused on central dysfimction related to poor cardiac pump function. However, the mechanisms are not exclusive to the heart and lungs, and the understanding of the pathophysiology of this dis- ease has evolved. Substantial attention has focused on defining the central versus peripheral mechanisms underlying the reduced functional capacity and exercise tolerance among patients with HF. In fact, physical training can improve exercise tolerance via peripheral adaptive mechanisms even in the absence of favorable central hemodynamic function. In addition, the drug trials performed to date in HFpEF that have focused on influencing cardiovascular function have not improved exercise capacity. This suggests that peripheral limitations may play a significant role in HF limiting exercise tolerance, a hallmark feature of HFpEF.
基金Under the auspices of Key Direction in Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-450, KZCX2-YW-422)
文摘The application of human induced oxygen consumption and carbon emission theory in urban region was summed up and on this base a new model of urban carbon and oxygen balance (UCOB) was constructed by calculating the carbon and oxygen fluxes. The purpose was to highlight the role of vegetation in urban ecosystems and evaluate the effects of various human activities on urban annual oxygen consumption and carbon emission. Hopefully,the model would be helpful in theory to keep the regional balance of carbon and oxygen,and provide guidance and support for urban vegetation planning in the future. To test the UCOB model,the Jimei District of Xiamen City,Fujian Province,China,a very typical urban region,was selected as a case study. The results turn out that Jimei′s vegetation service in oxygen emission and carbon sequestration could not meet the demand of the urban population,and more than 31.49 times of vegetation area should be added to meet the whole oxygen consumption in Jimei while 9.60 times of vegetation area are needed to meet the carbon sequestration targets. The results show that the new UCOB model is of a great potential to be applied to quantitative planning of urban vegetation and regional eco-compensation mechanisms.
基金Supported by The National Natural Science Foundation of China, No. 60471041 and 60901045
文摘AIM: To introduce a bioimpedance gastric motility mea- surement method based on an electrical-mechanical composite concept and a preliminary clinical application. METHODS: A noninvasive gastric motility measure- ment method combining electrogastrograrn (EGG) and impedance gastric motility (IGM) test was used. Prelim- inary clinical application studies of patients with func- tional dyspepsia (FD) and gastritis, as well as healthy controls, were carried out. Twenty-eight FD patients (mean age 40.9±9.7 years) and 40 healthy volun- teers (mean age 30.9±7.9 years) were involved. IGM spectrum was measured for both the healthy subjects and FD patients, and outcomes were compared in the FD patients before treatment and 1 wk and 3 wk after treatment. IGM parameters were obtained from 30 erosive gastritis patients (mean age 50.5±13.0 years) and 40 healthy adults, and IGM and EGG results were compared in the gastritis patients before treatment and 1 wk after treatment.RESULTS: There were significant differences in the IGM parameters between the FD patients and healthy subjects, and FD patients had a poorer gastric motility [percentage of normal frequency (PNF) 70.8±25.5 in healthy subjects and 28.3 =t= 16.9 in FD patients, P 〈 0.01]. After 1 wk administration of domperidone 10 mg, tid, the gastric motility of FD patients was not im- proved, although the EGG of the patients had returned to normal. After 3 wk of treatment, the IGM rhythm of the FD patients became normal. There was a significant difference in IGM parameters between the two groups (PNF 70.4:1:25.5 for healthy subjects and 36.1 4- 21.8 for gastritis patients, P 〈 0.05). The EGG rhythm of the gastritis patients returned to normal (frequency insta- bility coefficient 2.22±0.43 before treatment and 1.77 :t: 0.19 one wk after treatment, P 〈 0.05) after 1 wk of treatment with sodium rabeprazole tablets, 10 mg, qd, po, qm, while some IGM parameters showed a tenden- cy toward improvement but had not reached statistical significance. CONCLUSION: The electrical-mechanical composite measurement method showed an attractive clinical appli- cation prospect in gastric motility research and evaluation.
基金Project(JPPT-125-GH-039)supported by the Ministry of Science and Technology of ChinaProject(Z109021567)supported by Fundamental Research Funds for the Central Universities,China
文摘The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion couples.The interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering at583K.The thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,respectively.This indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate temperature.The pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.
文摘The literature shows that improvements in cognitive performance may be observed following an acute bout of exercise. However, evidence in support of the biological mechanisms of this effect is still limited. Findings from both rodent and human studies suggest brain-derived neu- rotrophic factor (BDNF) as a potential mechanism of the effect of acute exercise on memory. The molecular properties of BDNF allow this protein to be assessed in the periphery (pBDNF) (i.e., blood serum, blood plasma), making measurements of acute exercise-induced changes in BDNF concentration relatively accessible. Studies exploring the acute exercise--pBDNF--cognitive performance relationship have had mixed findings, but this may be more reflective of methodological differences between studies than it is a statement about the role of BDNE For example, significant associations have been observed between acute exercise-induced changes in pBDNF concentration and cognitive performance in studies assessing memory, and non-significant associations have been found in studies assessing non-memory cognitive domains. Three suggestions are made for future research aimed at understanding the role of BDNF as a biological mechanism of this relationship: 1) Assessments of cognitive performance may benefit from a focus on various types of memory (e.g., relational, spatial, long-term); 2) More finegrained measurements of pBDNF will allow for the assessment of concentrations of specific isoforms of the BDNF protein (i.e., immature, mature); 3) Statistical techniques designed to test the mediating role of pBDNF in the acute exercise-cognitive performance relationship should be utilized in order to make causal inferences.
文摘Reduced blood flow is the principle pathophysiologic event in acute ischernic stroke.Hence,flow augmentation is the most important goal in stroke management.Improvement of cerebral blood flow can be accomplished by proximal arterial recanalization or by other systemic approaches.Diastolic counterpulsation is a non-invasive method to improve the perfusion of heart,kidneys and brain.This review summarizes the history,possible mechanism and the role of external counterpulsation in ischemic stroke.
文摘We used a potent and specific monoclonal antibody to somatostatin to test the physiologic inhibitory role of the tetradecapeptide somatostatin on pancreatic secretion.Somatostatin immunoneutralization increased both the total amylase and volume of pancreatic secretion.Cholecystokinin-A receptor antagonism abolished the stimulatory effect of somatostatin immunoneutralization.We conclude that somatostatin tonically inhibits pancreatic secretion in fasted rats via inhibition of the release or action of cholecystokinin.Furthermore,the source of these peptides is likely islet delta cells and intrapancreatic neurons,respectively.
文摘The phenomenon described here has no scientific title, but occurs frequently in daily living, from science to philosophy, religion, and medicine. In every field of human endeavor, when a view is expressed, sharp and profound differences of opinion ensue. Initially, we coin this phenomenon as "understanding blindness" or "mind's awareness." Thereafter, we decide to refer to it as "mind blindness," a concept introduced to science by Professor Simon Baron-Cohen, who coins it for a cognitive disorder associated with autism, Asperger's syndrome, and schizophrenia. Baron-Cohen's usage has subsequently been extended to dementia, bi-polar disorders, antisocial personality disorders, and even normal aging. In our view, definition and identification of "mind blindness" in philosophy, religion, science, medicine, and at end-of-life care can help mankind to better understand mechanisms of human behavior, and the causes of conflicts, controversies, contradictions, and sharp differences of opinion in human life, and even to solve some of them.
基金supported by grants from the Shanghai Science and Technology Commission(NO.13490503600)National Natural Science Foundation of China (NO.31171004)
文摘Growing literature has demonstrated that exercise may be an effective prevention and treatment option for drug addiction. In the past few years, many studies have suggested that there were sex differences in all phases of drug addiction. However, very limited research has investigated sex differences in the effectiveness of exercise intervention in drug addiction and rehabilitation. In this mini review, we summarize the effect of sex on the results of using exercise to prevent and treat drug addiction. The studies we consider span various animal models and use multiple types of exercise to examine the effectiveness of exercise on the neurobiological mechanism of exercise rehabilitation. We believe that exercise as an adjuvant intervention strategy can be applied better in drug addiction prevention and recovery. Copyright 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.
文摘In this work, the stability of an endoreversible Curzon-Ahlbom engine is analyzed, using Van der Waals gas as a working substance and the corresponding efficiency for this engine working at temperatures withinthe maximum ecological regime. By mean s of a local stability analysis we find that a critical point of an almost linear system is stable andanalytically expressed in eigenvalues. After an arbitrarily small perturbation, the system state exponentially decays to a critical point, with either of two characteristic relaxation times, which are a function of the thermal conductance (a), heat capacity (C) and T=T2/T1. The behavior of relaxation times and solution of the systems are qualitatively shown by sketching its phase portrait, which results susceptible to operating regimes, i.e., the eigenvectors in the maximum ecological regime have a clockwise rotation with respect to the eigenvectors in the regime of maximumpower. Finally, it has to observe that afterto λvw = 1, approximation,ηVWE=4^-3ηC is obtained, where ηVWE is the Van der Waals efficiency atrnaximum ecological regime and r/c is Carnot's efficiency. Finally, it discussed the local stability and steady state of the energetic properties of the endoreversible engine.