Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Assoc...Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Association functional class. There is no consensus on the optimal surgical technique for this condition, including on whether to perform the procedure on a beating or an arrested heart and whether to perform valve repair or replacement. Methods: We analyzed four case series between 2015 and 2022 in which patients with secondary tricuspid regurgitation (TR) underwent valve repair on a beating heart and right atrial plication for a dilated right atrium. The TRI-SCORE was calculated for each patient. Results: All patients experienced a favorable postoperative course with significant improvements in heart failure symptoms. TR was markedly reduced;however, in one patient with concomitant mitral regurgitation (MR) and a high TRI-SCORE, MR worsened postoperatively. This patient later died from unknown causes due to multiple comorbidities in the late phase. Conclusions: Tricuspid valve repair on a beating heart was effective for improving the cardiac function, and the TRI-SCORE proved useful as a preoperative risk assessment tool. The underlying mechanism by which TR exacerbates MR requires further investigation.展开更多
BACKGROUND:Although the use of non-heart beating donors(NHBDs)could bridge the widening gap between organ demand and supply,its application to liver transplantation is limited due to the high incidence of primary graf...BACKGROUND:Although the use of non-heart beating donors(NHBDs)could bridge the widening gap between organ demand and supply,its application to liver transplantation is limited due to the high incidence of primary graft loss.Prevention of liver injury in NHBDs will benefit the results of transplantation.This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS:One hundred and four Wistar rats were randomly divided into 7 groups:normal control(n=8) controls 1,2 and 3(C1,C2,C3,n=16),and experimenta 1,2 and 3(E1,E2,E3,n=16).For groups C1 and E1,C2 and E2,and C3 and E3,the warm ischemia time was 0,30,and 45 minutes,respectively.Liver grafts were flushed with and preserved in 4℃Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group Recipients of each experimental group were injected with L-arginine(10 mg/kg body weight)by tail vein 10 minutes before portal vein reperfusion.Donors and recipients of each experimental control group were treated with norma saline.Then transplantation was performed.At 1,3,and 24 hours after portal vein reperfusion,blood samples were obtained to determine the levels of alanine aminotransferase (ALT),aspartate aminotransferase(AST),nitric oxide (NO)and plasma endothelin(ET).At 3 hours after porta vein reperfusion,grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation.RESULTS:At 1 hour after portal vein reperfusion,the levels of NO in groups E1,E2,E3 and C1,C2,C3 were lower,while the levels of plasma ET,serum ALT and AST were higher than those in the normal control group(P<0.05).At 1,3,and 24 hours,the levels of NO in groups E1,E2,E3 were higher,while the levels of plasma ET,serum ALT and AST were lower than those in the corresponding control groups(C1,C2,C3) (P<0.05).The levels of NO in groups C2 and C3 were lower than in group C1(P<0.05),and the level of NO in group C3 was lower than in group C2(P<0.05).At 1,3 and 24 hours, the levels of plasma ET,serum ALT,and AST in groups E1, E2,E3 were lower than those in the corresponding control groups(C1,C2,C3)(P<0.05).The levels of plasma ET,serum ALT,and AST were lower in group C3 than in groups C1 and C2(P<0.05).Pathological changes in groups E1,E2,E3 were milder than those in the corresponding experimental control groups(C1,C2,C3). CONCLUSIONS:The imbalance between NO and ET plays an important role in the development of ischemia- reperfusion injury of liver grafts from NHBDs.L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.展开更多
The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold r...The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold roll-beating,etc.However,the research on law of metal flow in the forming process of involute spline cold roll-beating is rare.According to the principle of involute spline cold roll-beating,the contact model between the rollers and the spline shaft blank in the process of cold roll-beating forming is established,and the theoretical analysis of metal flow in the cold roll-beating deforming region is proceeded.A finite element model of the spline cold roll-beating process is established,the formation mechanism of the involute spline tooth profile in cold roll-beating forming process is studied,and the node flow tracks of the deformation area are analyzed.The experimental research on the metal flow of cold roll-beating spline is conducted,and the metallographic structure variation,grain characteristics and metal flow line of the different tooth profile area are analyzed.The experimental results show that the particle flow directions of the deformable bodies in cold roll-beating deformation area are determined by the minimum moving resistance.There are five types of metal flow rules of the deforming region in the process of cold roll-beating forming.The characteristics of involute spline cold roll-beating forming are given,and the forming mechanism of involute spline cold roll-beating is revealed.This paper researches the law of metal flow in the forming process of involute spline cold roll-beating,which provides theoretical supports for solving the tooth profile forming quality problem.展开更多
Objective:To evaluate the efficacy and safety of Wenxin Keli for premature beats in structurally normal heart systematically.Methods:Eight databases at home and abroad were searched to collect randomized controlled tr...Objective:To evaluate the efficacy and safety of Wenxin Keli for premature beats in structurally normal heart systematically.Methods:Eight databases at home and abroad were searched to collect randomized controlled trials of Wenxin Keli for premature beats without cardiac diseases.The included literatures were systematically evaluated with Cochrane Handbook 5.1 evaluation criteria and tools,and Meta analysis was performed with software RevMan5.3.Results:A total of 13 randomized controlled trials with 1278 subjects were included.The exprimental group used Wenxin Keli alone while the control group used antiarrhythmic medicine.The Meta analysis results showed that the total effective rate(RR=1.06,95%CI[0.97,1.16],P=0.23)and clinical symptom effective rate(RR=1.16,95%CI[0.94,1.44],P=0.18)of Wenxin Keli on idiopathic premature beats was not significantly different from western medicine group.The subgroup analysis of total effective rate showed that Wenxin Keli had no significant difference with metoprolol(RR=1.04,95%CI[0.95,1.15],P=0.41),bisoprolol(RR=1.32,95%CI[0.85,2.05],P=0.22)and propanone(RR=1.07,95%CI[0.90,1.26],P=0.44).ECG changes showed that the PR intervals(MD=-12.57,95%CI[-16.15,-8.99],P<0.00001)and QTc intervals(MD=-8.09,95%CI[-15.52,-0.65],P=0.03)in the western medicine group were prolonged significantly more than those of Wenxin Keli.In terms of safety,the incidence of adverse reactions of Wenxin Keli was significantly less than that of western medicine group(RR=0.32,95%CI[0.19,0.54],P<0.0001).Conclusion:The efficacy of Wenxin Keli in the treatment of premature beats with structurally normal heart is accurate,and there are no serious adverse reactions.However,because of the low quality of the included papers,which affected the reliability of the conclusions,high-quality clinical research is needed to further demonstrate.展开更多
The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating...The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.展开更多
We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations i...We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations in a straight edge. However, for extreme-relativistic beams, the Fresnel oscillations turn into quantum damped beats.展开更多
We experimentally study the controllable generation of a beating signal using stored light pulses based on electro- magnetically induced transparency （EIT） in a solid medium. The beating signal relies on an asymmetr...We experimentally study the controllable generation of a beating signal using stored light pulses based on electro- magnetically induced transparency （EIT） in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.展开更多
In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat si...In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat signal between the photon echo field and the chirped field. The chirped detection model reveals that the period of the beat signal increases as the chirped rate and delay time increase. Additionally, a two-fold relationship between the modulation phase and the echo shift phase is obtained. The numerical simulations accord with the theoretical results obtained by the finite difference time domain(FDTD) method.展开更多
A nonlinear short-wave-averaged (surf beat) model is presented. The model is based on that of Roelvink (1993), but the numerical techniques used in the solution are based on the so-called weighted-averaged flux (WAF) ...A nonlinear short-wave-averaged (surf beat) model is presented. The model is based on that of Roelvink (1993), but the numerical techniques used in the solution are based on the so-called weighted-averaged flux (WAF) method (eg Watson et al., 1992), with time-operator splitting used for the treatment of some of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modelling breaking long waves. The short-wave (or primary-wave) energy equation is solved using a more traditional Lax-Wendroff technique. Results of validation indicate that the model performs satisfactorily in most respects.展开更多
Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 &...Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.展开更多
文摘Background: Isolated tricuspid valve disease remains a controversial indication for surgical intervention. Many patients referred for surgery already have a poor clinical condition and an advanced New York Heart Association functional class. There is no consensus on the optimal surgical technique for this condition, including on whether to perform the procedure on a beating or an arrested heart and whether to perform valve repair or replacement. Methods: We analyzed four case series between 2015 and 2022 in which patients with secondary tricuspid regurgitation (TR) underwent valve repair on a beating heart and right atrial plication for a dilated right atrium. The TRI-SCORE was calculated for each patient. Results: All patients experienced a favorable postoperative course with significant improvements in heart failure symptoms. TR was markedly reduced;however, in one patient with concomitant mitral regurgitation (MR) and a high TRI-SCORE, MR worsened postoperatively. This patient later died from unknown causes due to multiple comorbidities in the late phase. Conclusions: Tricuspid valve repair on a beating heart was effective for improving the cardiac function, and the TRI-SCORE proved useful as a preoperative risk assessment tool. The underlying mechanism by which TR exacerbates MR requires further investigation.
基金a grant from the Science & Technology Development Foundation of Guangdong Health Bureau(No.2006345).
文摘BACKGROUND:Although the use of non-heart beating donors(NHBDs)could bridge the widening gap between organ demand and supply,its application to liver transplantation is limited due to the high incidence of primary graft loss.Prevention of liver injury in NHBDs will benefit the results of transplantation.This study was conducted to evaluate the protective effects of L-arginine on liver grafts from NHBDs. METHODS:One hundred and four Wistar rats were randomly divided into 7 groups:normal control(n=8) controls 1,2 and 3(C1,C2,C3,n=16),and experimenta 1,2 and 3(E1,E2,E3,n=16).For groups C1 and E1,C2 and E2,and C3 and E3,the warm ischemia time was 0,30,and 45 minutes,respectively.Liver grafts were flushed with and preserved in 4℃Euro-collins solution containing 1 mmol/L L-arginine for 1 hour in each experimental group Recipients of each experimental group were injected with L-arginine(10 mg/kg body weight)by tail vein 10 minutes before portal vein reperfusion.Donors and recipients of each experimental control group were treated with norma saline.Then transplantation was performed.At 1,3,and 24 hours after portal vein reperfusion,blood samples were obtained to determine the levels of alanine aminotransferase (ALT),aspartate aminotransferase(AST),nitric oxide (NO)and plasma endothelin(ET).At 3 hours after porta vein reperfusion,grafts samples were fixed in 2.5% glutaraldehyde for electron microscopic observation.RESULTS:At 1 hour after portal vein reperfusion,the levels of NO in groups E1,E2,E3 and C1,C2,C3 were lower,while the levels of plasma ET,serum ALT and AST were higher than those in the normal control group(P<0.05).At 1,3,and 24 hours,the levels of NO in groups E1,E2,E3 were higher,while the levels of plasma ET,serum ALT and AST were lower than those in the corresponding control groups(C1,C2,C3) (P<0.05).The levels of NO in groups C2 and C3 were lower than in group C1(P<0.05),and the level of NO in group C3 was lower than in group C2(P<0.05).At 1,3 and 24 hours, the levels of plasma ET,serum ALT,and AST in groups E1, E2,E3 were lower than those in the corresponding control groups(C1,C2,C3)(P<0.05).The levels of plasma ET,serum ALT,and AST were lower in group C3 than in groups C1 and C2(P<0.05).Pathological changes in groups E1,E2,E3 were milder than those in the corresponding experimental control groups(C1,C2,C3). CONCLUSIONS:The imbalance between NO and ET plays an important role in the development of ischemia- reperfusion injury of liver grafts from NHBDs.L-arginine can attenuate injury in liver grafts from NHBDs by improving the balance between NO and ET.
基金supported by National Natural Science Foundation of China(Grant Nos.5107512450975229)Doctoral Foundation of Henan University of Science and Technology of China(Grant No.09001331)
文摘The present research on involute spline cold roll-beating forming is mainly about the principles and motion relations of cold roll-beating,the theory of roller design,and the stress and strain field analysis of cold roll-beating,etc.However,the research on law of metal flow in the forming process of involute spline cold roll-beating is rare.According to the principle of involute spline cold roll-beating,the contact model between the rollers and the spline shaft blank in the process of cold roll-beating forming is established,and the theoretical analysis of metal flow in the cold roll-beating deforming region is proceeded.A finite element model of the spline cold roll-beating process is established,the formation mechanism of the involute spline tooth profile in cold roll-beating forming process is studied,and the node flow tracks of the deformation area are analyzed.The experimental research on the metal flow of cold roll-beating spline is conducted,and the metallographic structure variation,grain characteristics and metal flow line of the different tooth profile area are analyzed.The experimental results show that the particle flow directions of the deformable bodies in cold roll-beating deformation area are determined by the minimum moving resistance.There are five types of metal flow rules of the deforming region in the process of cold roll-beating forming.The characteristics of involute spline cold roll-beating forming are given,and the forming mechanism of involute spline cold roll-beating is revealed.This paper researches the law of metal flow in the forming process of involute spline cold roll-beating,which provides theoretical supports for solving the tooth profile forming quality problem.
基金National Natural Science Foundation of China(No.81774128)National key Research and development program(No.2019YFC1708404)。
文摘Objective:To evaluate the efficacy and safety of Wenxin Keli for premature beats in structurally normal heart systematically.Methods:Eight databases at home and abroad were searched to collect randomized controlled trials of Wenxin Keli for premature beats without cardiac diseases.The included literatures were systematically evaluated with Cochrane Handbook 5.1 evaluation criteria and tools,and Meta analysis was performed with software RevMan5.3.Results:A total of 13 randomized controlled trials with 1278 subjects were included.The exprimental group used Wenxin Keli alone while the control group used antiarrhythmic medicine.The Meta analysis results showed that the total effective rate(RR=1.06,95%CI[0.97,1.16],P=0.23)and clinical symptom effective rate(RR=1.16,95%CI[0.94,1.44],P=0.18)of Wenxin Keli on idiopathic premature beats was not significantly different from western medicine group.The subgroup analysis of total effective rate showed that Wenxin Keli had no significant difference with metoprolol(RR=1.04,95%CI[0.95,1.15],P=0.41),bisoprolol(RR=1.32,95%CI[0.85,2.05],P=0.22)and propanone(RR=1.07,95%CI[0.90,1.26],P=0.44).ECG changes showed that the PR intervals(MD=-12.57,95%CI[-16.15,-8.99],P<0.00001)and QTc intervals(MD=-8.09,95%CI[-15.52,-0.65],P=0.03)in the western medicine group were prolonged significantly more than those of Wenxin Keli.In terms of safety,the incidence of adverse reactions of Wenxin Keli was significantly less than that of western medicine group(RR=0.32,95%CI[0.19,0.54],P<0.0001).Conclusion:The efficacy of Wenxin Keli in the treatment of premature beats with structurally normal heart is accurate,and there are no serious adverse reactions.However,because of the low quality of the included papers,which affected the reliability of the conclusions,high-quality clinical research is needed to further demonstrate.
基金National Natural Science Foundation of China(Nos.51675486 51505239 51575496)
文摘The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.
文摘We solve the relativistic Dirac equation for the shutter problem. We prove that, at intermediate relativistic energies, the probability density oscillates in time in a similar way to the optical Fresnel oscillations in a straight edge. However, for extreme-relativistic beams, the Fresnel oscillations turn into quantum damped beats.
基金Project supported by the National Basic Research Program of China （Grant No. 201 ICB921603）, the National Natural Science Foundation of China （Grant Nos. 11374126, 10904048, 11074097, 11004079, 11004080, and 11247201）, the China Postdoctoral Science Foundation （Grant Nos. 2011M500924 and 2013T60317）. and the National Fund for Fosterin~ Talents of Basic Science （Grant No. J I 103202）.
文摘We experimentally study the controllable generation of a beating signal using stored light pulses based on electro- magnetically induced transparency （EIT） in a solid medium. The beating signal relies on an asymmetric procedure of light storage and retrieval. After storing the probe pulse into the spin coherence under the EIT condition, two-color control fields with opposite detunings instead of the initial control field are used to scatter the stored spin coherence. The controllable beating signal is generated due to alternative constructive and destructive interferences in the retrieved signal intensities. The beating of the two-color control fields is mapped into the beating of weak probe fields by using atomic spin coherence. This beating signal will be important in precise atomic spectroscopy and fast quantum limited measurements.
基金Project supported by the Tianjin Research Program of Application Foundation and Advanced Technology,China(Grant No.15JCQNJC01100)
文摘In this paper, we propose a scheme for photon echo chirped detection process composed of additional modulation pulses to obtain controllable geometric phase. The geometric phases are observed and measured by a beat signal between the photon echo field and the chirped field. The chirped detection model reveals that the period of the beat signal increases as the chirped rate and delay time increase. Additionally, a two-fold relationship between the modulation phase and the echo shift phase is obtained. The numerical simulations accord with the theoretical results obtained by the finite difference time domain(FDTD) method.
文摘A nonlinear short-wave-averaged (surf beat) model is presented. The model is based on that of Roelvink (1993), but the numerical techniques used in the solution are based on the so-called weighted-averaged flux (WAF) method (eg Watson et al., 1992), with time-operator splitting used for the treatment of some of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modelling breaking long waves. The short-wave (or primary-wave) energy equation is solved using a more traditional Lax-Wendroff technique. Results of validation indicate that the model performs satisfactorily in most respects.
文摘Diagnostic techniques of CEOF, power spectrum and bandpass filter wave are applied in this paper to analyze the seasonal northward beating of the northern subtropical high using day to day geopotential fields of 2.5 ×2.5 at 500 hPa May through July in 1988 and 1991. It is concluded that it is globally observed that the subtropical high has northward beats that propagate westward; the source of beating mainly lies in the region of Arabian Sea and central Pacific and the sink in eastern Pacific; the seasonal beating is dominated by effects of the disturbance field; low frequency oscillation plays a key role in the beating and the westward propagation so that the difference in the latter in individual years is caused by the varying source of disturbance and the low frequency waves it excites.
