The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded...The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded dielectric resonator included in stripline elevated ferrite film circulator, the off diagonal components of the permeability tensor are taken as the perturbation. The electromagnetic fields computations are done for unperturbed structure. The dipolar resonant frequencies corresponding to harmonics of the resonant modes are then calculated using the perturbation integrals. The quality factor of the circulator is derived in terms of these dipolar resonant frequencies. Energy integrals are calculated to find the energy stored in the ferrite and dielectic layers. An analytical expression for the input conductance of the elevated ferrite film circulators is derived by using the quality factor and energy integrals. In this expression the ferrite and dielectric layers can have different permittivities. Some discussions about the effect of ferrite film thickness and permittivity mismatch on the bandwidth of the circulator are investigated by HFSS commercial software.展开更多
Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveg...Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveguides and ferrite disks to support non-reciprocal mode coupling.The simulated performance of symmetrically designed circulator shows that it has an insertion loss of roughly 0.5 dB while the isolation and return loss is more than 12 dB in the frequency range of 6.0 GHz–10.0 GHz(relative bandwidth of 50%).Equivalent circuit model has been proposed to explain the operating mechanism of the plasmonic circulator.The equivalent circuit model,numerical simulations,and experimental results are consistent with each other,which demonstrates the good performance of the proposed plasmonic circulator.展开更多
Portal hypertension is a clinical syndrome which leads to several clinical complications,such as the formation and rupture of esophageal and/or gastric varices,ascites,hepatic encephalopathy and hepato-renal syndrome....Portal hypertension is a clinical syndrome which leads to several clinical complications,such as the formation and rupture of esophageal and/or gastric varices,ascites,hepatic encephalopathy and hepato-renal syndrome.In cirrhosis,the primary cause of the increase in portal pressure is the enhanced resistance to portal outflow.However,also an increase in splanchnic blood flow worsens and maintains portal hypertension.The vasodilatation of arterial splanchnic vessels and the opening of collateral circulation are the determinants of the increased splanchnic blood flow.Several vasoactive systems/substances,such as nitric oxide,cyclooxygenase-derivatives,carbon monoxide and endogenous cannabinoids are activated in portal hypertension and are responsible for the marked splanchnic vasodilatation.Moreover,an impaired reactivity to vasoconstrictor systems,such as the sympathetic nervous system,vasopressin,angiotensinⅡand endothelin-1,plays a role in this process.The opening of collateral circulation occurs through the reperfusion and dilatation of preexisting vessels,but also through the generation of new vessels.Splanchnic vasodilatation leads to the onset of the hyperdynamic circulatory syndrome,a syndrome which occurs in pa-tients with portal hypertension and is characterized by increased cardiac output and heart rate,and decreased systemic vascular resistance with low arterial blood pressure.Understanding the pathophysiology of splanchnic vasodilatation and hyperdynamic circulatory syndrome is mandatory for the prevention and treatment of portal hypertension and its severe complications.展开更多
Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on ...Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D_3, A_8, a_0, j_0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D_3 and A_8 are major influence factors on hydrodynamic characteristics of the pump, while a_0, j_0 and Rt are minor influence factors. The minimum contribution from both D_3 and A_8 is 58% on head, and maximum contribution from both D_3 and A_8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D_3/D_2 and A_8/A_(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D_3/D_2. While for the other volute parameters a_0, j_0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force.展开更多
AIM: Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis. The aim of the study was to evaluate changes in rnicroperfusion of the pancreas, liver, kid...AIM: Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis. The aim of the study was to evaluate changes in rnicroperfusion of the pancreas, liver, kidney, stomach,colon, skeletal muscle, and to investigate the influence of heparin on the organ rnicrocirculation in caerulein-induced experimental acute pancreatitis.METHODS: Acute pancreatitis was induced by 4 intraperitoneal injections of caerulein (Cn) (15 μg/kg). The organ microcirculation was measured by laser Doppler flowrnetry. Serum interleukin 6 and hernatocrit levels were analysed.RESULTS: Acute pancreatitis resulted in a significant drop of microperfusion in all examined organs. Heparin administration (2×2.5 mg/kg) improved the rnicrocirculation in pancreas (36.9±4% vs75.9±10%), liver (56.6±6% vs 75.2±16%), kidney (45.1±6% vs79.3±5%), stomach (65.2±8% vs78.1±19%), colon (69.8±6% vs 102.5±19%),and skeletal muscle (59.2±6% vs 77.9±13%). Heparin treatment lowered IL-6 (359.0±66 U/mL vs 288.5±58 U/mL) and hematocrit level (53±4% vs 46±3%).CONCLUSION: Hepadn administration has a positive influence on organ microcirculatory disturbances accompanying experimental Cn-induced acute pancreatitis.展开更多
A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circ...A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.展开更多
Based on the scatter matrix of the four-port lossless mismatched circulator, the phase differential equation of the injection-locked magnetron is derived by comparing different effects of the mismatched and perfect ci...Based on the scatter matrix of the four-port lossless mismatched circulator, the phase differential equation of the injection-locked magnetron is derived by comparing different effects of the mismatched and perfect circulator on the injection ratio. Besides, the locking range of the injection-locked magnetron with the mismatched circulator is deduced by functional operation. In addition, the phase differential equation and the locked bandwidth of the injection-locked system with a mismatched circulator are compared with those of the small injection-ratio case with a perfect circulator. The influence of the circulator reflection coefficient on the injection-locked magnetron is also analyzed by numerical calculation.Theoretical analysis shows that the decrement of the locked bandwidth is less than 1% and decrement of the stable phase difference is less than 1.2% when the reflection coefficient is less than 0.1.展开更多
Vertebrobasilar dolichoectasia(VBD),a rare posterior circulation vascular variant disease,is an important risk factor for many acute cerebrovascular diseases.An insufficient understanding of VBD often leads to misdiag...Vertebrobasilar dolichoectasia(VBD),a rare posterior circulation vascular variant disease,is an important risk factor for many acute cerebrovascular diseases.An insufficient understanding of VBD often leads to misdiagnose.Two cases of VBD that were initially diagnosed as posterior circulation watershed infarction are reported here.Absence of common causes of stroke including hypoperfusion,blood system diseases,carotid and aortic dissection,and eosinophil elevation,the symptoms of the 2 patients met the diagnostic criteria of VBD.Both patients displayed symptoms that were in line with the Traditional Chinese Medicine(TCM)syndrome pattern of"Qi deficiency and blood stasis".Accordingly,they were comprehensively treated with Supplementing Qi and activating blood circulation method.The clinical manifestations of the 2 patients were remarkably improved and no recurrence of watershed infarction was found in a 1-year follow-up.A detailed medical history and laboratory examination are capable of improving diagnostic accuracy of VBD.TCM treatment based on syndrome identification might be a promising candidate for VBD management.展开更多
文摘The main idea of this paper is to find an analytical formula for the input conductance of an elevated ferrite film circu-lator to match it systematically to the desired matching network. For solving the ferrite loaded dielectric resonator included in stripline elevated ferrite film circulator, the off diagonal components of the permeability tensor are taken as the perturbation. The electromagnetic fields computations are done for unperturbed structure. The dipolar resonant frequencies corresponding to harmonics of the resonant modes are then calculated using the perturbation integrals. The quality factor of the circulator is derived in terms of these dipolar resonant frequencies. Energy integrals are calculated to find the energy stored in the ferrite and dielectic layers. An analytical expression for the input conductance of the elevated ferrite film circulators is derived by using the quality factor and energy integrals. In this expression the ferrite and dielectric layers can have different permittivities. Some discussions about the effect of ferrite film thickness and permittivity mismatch on the bandwidth of the circulator are investigated by HFSS commercial software.
基金Project supported by the Six-Talent-Peaks Project in Jiangsu Province of China(Grant No.XYDXX-072)the National Natural Science Foundation of China(Grant No.61372048).
文摘Circulators play a significant role in radar and microwave communication systems.This paper proposes a broadband and highly efficient plasmonic circulator,which consists of spoof surface plasmon polaritons(SSPPs)waveguides and ferrite disks to support non-reciprocal mode coupling.The simulated performance of symmetrically designed circulator shows that it has an insertion loss of roughly 0.5 dB while the isolation and return loss is more than 12 dB in the frequency range of 6.0 GHz–10.0 GHz(relative bandwidth of 50%).Equivalent circuit model has been proposed to explain the operating mechanism of the plasmonic circulator.The equivalent circuit model,numerical simulations,and experimental results are consistent with each other,which demonstrates the good performance of the proposed plasmonic circulator.
文摘Portal hypertension is a clinical syndrome which leads to several clinical complications,such as the formation and rupture of esophageal and/or gastric varices,ascites,hepatic encephalopathy and hepato-renal syndrome.In cirrhosis,the primary cause of the increase in portal pressure is the enhanced resistance to portal outflow.However,also an increase in splanchnic blood flow worsens and maintains portal hypertension.The vasodilatation of arterial splanchnic vessels and the opening of collateral circulation are the determinants of the increased splanchnic blood flow.Several vasoactive systems/substances,such as nitric oxide,cyclooxygenase-derivatives,carbon monoxide and endogenous cannabinoids are activated in portal hypertension and are responsible for the marked splanchnic vasodilatation.Moreover,an impaired reactivity to vasoconstrictor systems,such as the sympathetic nervous system,vasopressin,angiotensinⅡand endothelin-1,plays a role in this process.The opening of collateral circulation occurs through the reperfusion and dilatation of preexisting vessels,but also through the generation of new vessels.Splanchnic vasodilatation leads to the onset of the hyperdynamic circulatory syndrome,a syndrome which occurs in pa-tients with portal hypertension and is characterized by increased cardiac output and heart rate,and decreased systemic vascular resistance with low arterial blood pressure.Understanding the pathophysiology of splanchnic vasodilatation and hyperdynamic circulatory syndrome is mandatory for the prevention and treatment of portal hypertension and its severe complications.
基金Supported by National Natural Science Foundation of China(Grant No.51239005)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LQ15E090004,LQ15E090005)Project of Zhejiang Education,China(Grant No.Y201432222)
文摘Improper design of volute geometry can be the main cause that leads to unsteady pressure pulsation and radial force in pumps. Therefore, it is important to understand the influence of volute geometrical parameters on hydrodynamic characteristics of pump and the mechanism. However, the existing studies are limited to investigate the influence of only one or two volute geometrical parameters each time, and a systematic study of the influence of the combinations of different volute geometrical parameters on the pump's hydrodynamic characteristics is missing. In this paper, a study on the understanding of the influence of volute geometrical variations on hydrodynamic characteristics of a high speed circulator pump by using computational fluid dynamics(CFD) technology is presented. Five main volute geometrical parameters D_3, A_8, a_0, j_0 and Rt are selected and 25 different volute configurations are generated by using design of experiments(DOE) method. The 3D unsteady flow numerical simulations, which are based on the SST k-w turbulence model and sliding mesh technique provided by CFX, are executed on the 25 different volute configurations. The hydraulic performance, pressure pulsation and unsteady radial force inside the pump at design condition are obtained and analyzed. It has been found that volute geometrical parameters D_3 and A_8 are major influence factors on hydrodynamic characteristics of the pump, while a_0, j_0 and Rt are minor influence factors. The minimum contribution from both D_3 and A_8 is 58% on head, and maximum contribution from both D_3 and A_8 is 90% on pressure pulsation. Regarding the pressure pulsation intensity, two peaks can be found. One is in the tongue area and the other is in the diffusor area. The contributions are around 60% from tongue and 25% from diffusor, respectively. The amplitude of pressure pulsation has a quadratic polynomial functional relationship with respect to D_3/D_2 and A_8/A_(10), and fluctuating level of radial force has a quadratic polynomial functional relationship with respect to D_3/D_2. While for the other volute parameters a_0, j_0 and Rt, no special function has been found related to pressure pulsation and radial force. The presented work could be a useful guideline in engineering practice when designing a circulator pump with low hydrodynamic force.
基金Supported by Medical University of Gda■sk,grant W-120,Poland
文摘AIM: Microcirculatory disturbances are important early pathophysiological events in various organs during acute pancreatitis. The aim of the study was to evaluate changes in rnicroperfusion of the pancreas, liver, kidney, stomach,colon, skeletal muscle, and to investigate the influence of heparin on the organ rnicrocirculation in caerulein-induced experimental acute pancreatitis.METHODS: Acute pancreatitis was induced by 4 intraperitoneal injections of caerulein (Cn) (15 μg/kg). The organ microcirculation was measured by laser Doppler flowrnetry. Serum interleukin 6 and hernatocrit levels were analysed.RESULTS: Acute pancreatitis resulted in a significant drop of microperfusion in all examined organs. Heparin administration (2×2.5 mg/kg) improved the rnicrocirculation in pancreas (36.9±4% vs75.9±10%), liver (56.6±6% vs 75.2±16%), kidney (45.1±6% vs79.3±5%), stomach (65.2±8% vs78.1±19%), colon (69.8±6% vs 102.5±19%),and skeletal muscle (59.2±6% vs 77.9±13%). Heparin treatment lowered IL-6 (359.0±66 U/mL vs 288.5±58 U/mL) and hematocrit level (53±4% vs 46±3%).CONCLUSION: Hepadn administration has a positive influence on organ microcirculatory disturbances accompanying experimental Cn-induced acute pancreatitis.
基金supported by the National Basic Research Program of China under Grant No. 61363Z06.1
文摘A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.
基金Project supported by the National Basic Research Program of China(Grant No.2013CB328901)the National Natural Science Foundation of China(Grant No.11305177)
文摘Based on the scatter matrix of the four-port lossless mismatched circulator, the phase differential equation of the injection-locked magnetron is derived by comparing different effects of the mismatched and perfect circulator on the injection ratio. Besides, the locking range of the injection-locked magnetron with the mismatched circulator is deduced by functional operation. In addition, the phase differential equation and the locked bandwidth of the injection-locked system with a mismatched circulator are compared with those of the small injection-ratio case with a perfect circulator. The influence of the circulator reflection coefficient on the injection-locked magnetron is also analyzed by numerical calculation.Theoretical analysis shows that the decrement of the locked bandwidth is less than 1% and decrement of the stable phase difference is less than 1.2% when the reflection coefficient is less than 0.1.
基金the 2019 Major Difficult Diseases Clinical Collaboration Capacity Building Project of Traditional Chinese and Western Medicine-cerebral Infarction(No.YW082)。
文摘Vertebrobasilar dolichoectasia(VBD),a rare posterior circulation vascular variant disease,is an important risk factor for many acute cerebrovascular diseases.An insufficient understanding of VBD often leads to misdiagnose.Two cases of VBD that were initially diagnosed as posterior circulation watershed infarction are reported here.Absence of common causes of stroke including hypoperfusion,blood system diseases,carotid and aortic dissection,and eosinophil elevation,the symptoms of the 2 patients met the diagnostic criteria of VBD.Both patients displayed symptoms that were in line with the Traditional Chinese Medicine(TCM)syndrome pattern of"Qi deficiency and blood stasis".Accordingly,they were comprehensively treated with Supplementing Qi and activating blood circulation method.The clinical manifestations of the 2 patients were remarkably improved and no recurrence of watershed infarction was found in a 1-year follow-up.A detailed medical history and laboratory examination are capable of improving diagnostic accuracy of VBD.TCM treatment based on syndrome identification might be a promising candidate for VBD management.
