The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate s...The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate significantly affects the phase distribution of the as-cast Cu-15Ni-8Sn alloy.The primary and secondary dendritic spacing reduces and eventually becomes stable as the solidification rate increases.Meanwhile,the size of the primary phase decreases,and its distribution becomes more uniform.The most severe segregation problem of this alloy has been greatly improved.Upon solidification at 100μm/s,the as-cast Cu-15Ni-8Sn alloy consists of the α-Cu matrix,γ-CuNi_(2)Sn phase,discontinuous precipitation structure,modulated structure,and DO_(22) ordered phases.However,as the solidification rate increases,the discontinuous precipitation structure,modulated structures,and DO_(22) ordered phases decrease and even disappear,reducing hardness.As the solidification rate increases,after homogenization treatment,the composition and microhardness distributions of Cu-15Ni-8Sn alloy become more uniform.The time for homogenization is also shortened.It reduces production energy usage and facilitates further mechanical processing.展开更多
Based on the analysis of physical and chemical properties of soil,nutrient elements and biochemical compositions of tea leaves,the relationship between soil characters and tea quality was studied.The results showed th...Based on the analysis of physical and chemical properties of soil,nutrient elements and biochemical compositions of tea leaves,the relationship between soil characters and tea quality was studied.The results showed that soil total phosphorus,potassium,available potassium,copper and zinc were the main factors which affected and limited the content of nutrient elements of tea leaves.Furthermore,soil pH,organic matter,total nitrogen,potassium,exchangeable calcium,magnesium,available copper and zinc were the main factors affecting and limiting the content of biochemical compositions in tea leaves.Tea quality could be improved by controlling these soil factors.展开更多
Single-crystalline Mn_(3)O_(4)nanoflakes were grown on manganese sheets by one-step thermal oxidation process at 360-500℃in ambient atmosphere.The samples were characterized by scanning electron microscope(SEM),X-ray...Single-crystalline Mn_(3)O_(4)nanoflakes were grown on manganese sheets by one-step thermal oxidation process at 360-500℃in ambient atmosphere.The samples were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),Raman and transmission electron microscope(TEM).The nanoflakes with a size of 15-20 nm in thickness,~60 nm in width,and~210 nm in length are obtained at 360℃for 24 h.A surface diffusion mechanism is proposed to explain the growth of manganese oxide nanostructures via thermal oxidation,which includes two steps:manganese oxide(MnO/Mn_(3)O_(4))layers form firstly,and then Mn_(3)O_(4)nanostructures grow above the upper metal oxide layer to form multi-layered structures,MnO/Mn_(3)O_(4)/Mn_(3)O_(4)-nanoflakes.The nucleation and growth of Mn_(3)O_(4)nanostructures are related to the surface energy and different growth rates along different crystal directions,which are controlled by the diffusion of the metal and gas molecule.展开更多
Objective To compare the short-term clinical effect and electrical parameters of His-purkinje bundle pacing(HPBP) and right ventricular inflow tract septal pacing(RVIP) in the elderly. Methods Between April 2017 and S...Objective To compare the short-term clinical effect and electrical parameters of His-purkinje bundle pacing(HPBP) and right ventricular inflow tract septal pacing(RVIP) in the elderly. Methods Between April 2017 and September 2019, sixty patients with indications for permanent cardiac pacing and resynchronization therapy in Beijing Anzhen Hospital were divided into the HPBP and RVIP groups, and were analyzed. A ventricular pacing lead was implanted in left ventricular septal sites with left bundle potentials or His potentials in the HPBP group. The lead was placed in right ventricular inflow tract septal sites close to distal His-bundle regions without potentials from the His-purkinje conduction system in the RVIP group. Lead impedance, R wave amplitude, pacing thresholds, QRS duration, left ventricular ejection fraction(LVEF), and left ventricular end-diastolic diameter(LVEDD), mitral regurgitation area reflux, QTc, T wave directivity, Tp-e and Tp-e/QT ratio were compared between the HPBP and RVIP groups during the procedure and the short-month follow-up. Results No significant differences were found in lead impedance, R wave amplitude, QRS duration, LVEF, LVEDD, mitral regurgitation area reflux, QTc, T wave directivity, Tp-e and Tp-e/QT ratio between the HPBP and RVIP groups. However, the pacing threshold was significantly lower in the HPBP group than in the RVIP group(0.7 ± 0.2 vs. 0.9 ± 0.3 V, P = 0.02). Conclusions The efficacy and electrical parameters of HPBP is comparable with RVIP during the procedure and the short-term follow-up.展开更多
BACKGROUND The prognosis of many patients with distant metastatic hepatocellular carcinoma(HCC)improved after they survived for several months.Compared with tradi-tional survival analysis,conditional survival(CS)which...BACKGROUND The prognosis of many patients with distant metastatic hepatocellular carcinoma(HCC)improved after they survived for several months.Compared with tradi-tional survival analysis,conditional survival(CS)which takes into account changes in survival risk could be used to describe dynamic survival probabilities.AIM To evaluate CS of distant metastatic HCC patients.METHODS Patients diagnosed with distant metastatic HCC between 2010 and 2015 were extracted from the Surveillance,Epidemiology and End Results database.Univariate and multivariate Cox regression analysis were used to identify factors for overall survival(OS),while competing risk model was used to identify risk factors for cancer-specific survival(CSS).Six-month CS was used to calculate the probability of survival for an additional 6 mo at a specific time after initial diagnosis,and standardized difference(d)was used to evaluate the survival differences between subgroups.Nomograms were constructed to predict CS.Positiveα-fetoprotein expression,higher T stage(T3 and T4),N1 stage,non-primary site surgery,non-chemotherapy,non-radiotherapy,and lung metastasis were independent risk factors for actual OS and CSS through univariate and multivariate analysis.Actual survival rates decreased over time,while CS rates gradually increased.As for the 6-month CS,the survival difference caused by chemotherapy and radiotherapy gradually disappeared over time,and the survival difference caused by lung metastasis reversed.Moreover,the influence of age and gender on survival gradually appeared.Nomograms were fitted for patients who have lived for 2,4 and 6 mo to predict 6-month conditional OS and CSS,respectively.The area under the curve(AUC)of nomograms for conditional OS decreased as time passed,and the AUC for conditional CSS gradually increased.CONCLUSION CS for distant metastatic HCC patients substantially increased over time.With dynamic risk factors,nomograms constructed at a specific time could predict more accurate survival rates.展开更多
Subcutaneous implantable cardioverter-defi brillator(S-ICD)therapy has become a viable alternative to conventional transvenous ICD implantation.Patients with congenitally corrected transposition of the great arteries(...Subcutaneous implantable cardioverter-defi brillator(S-ICD)therapy has become a viable alternative to conventional transvenous ICD implantation.Patients with congenitally corrected transposition of the great arteries(ccTGA)have a high risk of sudden cardiac death due to malignant arrhythmia.The interaction between the S-ICD system and the transvenous pacemaker system is not fully understood.We report a case of S-ICD implantation in a patient with ccTGA and a DDD pacemaker.The patient was a 30-year-old man with a previously placed pacemaker with diagnoses of congenital heart disease,ccTGA(SLL),left atrioventricular valve insuffi ciency,and third-degree atrioventricular block.He presented with an out-of-hospital cardiac arrest,and an S-ICD was implanted to prevent sudden cardiac death.Defi brillation checks were performed successfully.We tested the compatibility of the DDD pacemaker with the S-ICD and found that there was no interference between them.In conclusion,an S-ICD system is a reasonable and safe option in patients with ccTGA.展开更多
Background:The symptomatic bradyarrhythmia is Class I indication for pacing therapy which is not a radical cure.The present study aimed to assess the feasibility and to present the initial results of the restricted ab...Background:The symptomatic bradyarrhythmia is Class I indication for pacing therapy which is not a radical cure.The present study aimed to assess the feasibility and to present the initial results of the restricted ablation of the parasympathetic innervation surrounding sinus and atrioventricular(AV)nodes for treating patients with bradyarrhythmia.Methods:A total of 13 patients with cardiogenic syncope were included from May 2008 to June 2015.Under the guidance of fluoroscopy and/or three-dimensional geometry by 64-slice spiral computed tomography,atrial activation sequence in sinus rhythm was mapped.Chamber geometry was reconstructed manually or automatically using the Niobe II magnetic navigation system integrated with the CARTO-remote magnetic technology(RMT)system.Cardioneuroablation was targeted at the high-amplitude fractionated electrograms surrounding the regions of His bundle and the site with the earliest activation in sinus rhythm.Areas surrounding the sinus node,AV node,and the phrenic nerve were avoided.Results:Thirteen patients completed the studies.Ablation was successfully performed in 12 patients and failed in one.The highfrequency potential was recorded in atrial electrograms surrounding the sinus or AV nodes in all the patients and disappeared in 15 s after radiofrequency applications.The vagal reaction was observed before the improvement of the sinus and AV node function.No complications occurred during the procedures.Patients were followed up for a mean of 13.0±5.9 months.During the follow up ten patients remained free of symptoms,and two patients had a permanent cardiac pacemaker implanted due to spontaneous recurrence of syncope.The heart rate of post-ablation was higher than pre-ablation(69.0±11.0 vs.49.0±10.0 beats/min,t=4.56,P=0.008).The sinus node recovery time,Wenckebach block point,and atrium-His bundle interval were significantly shorter after ablation(1386.0±165.0 vs.921.0±64.0 ms,t=7.45,P=0.002;590.0±96.0 vs.464.0±39.0 ms,t=2.38,P=0.023;106.0±5.0 vs.90.0±12.0 ms,t=9.80,P=0.013 before and after ablation procedure,respectively).Conclusions:Ablation of sinoatrial and AV nodal peripheral fibrillar myocardium electrical activity might provide a new treatment to ameliorate paroxysmal sinus node dysfunction,high degree AV block,and vagal-mediated syncope.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0714400)Science and Technology Projects of Jiangxi Provincial Department of Education(Grant Nos.GJ210843 and GJJ200873)+2 种基金Scientific Research Starting Foundation for Advanced Talents of Jiangxi University of Science and Technology(Grant No.205200100570)the Project of the Key Scientific and Technological of Jiangxi Province(Grant No.20181BCB19003)Ningbo Enterprise Innovation Consortium Special Project(Grant No.2021H003).
文摘The microstructures and mechanical properties of the directionally solidified Cu-15Ni-8Sn alloy were investigated at solidification rates ranging from 100 to 3000μm/s.The results showed that the solidification rate significantly affects the phase distribution of the as-cast Cu-15Ni-8Sn alloy.The primary and secondary dendritic spacing reduces and eventually becomes stable as the solidification rate increases.Meanwhile,the size of the primary phase decreases,and its distribution becomes more uniform.The most severe segregation problem of this alloy has been greatly improved.Upon solidification at 100μm/s,the as-cast Cu-15Ni-8Sn alloy consists of the α-Cu matrix,γ-CuNi_(2)Sn phase,discontinuous precipitation structure,modulated structure,and DO_(22) ordered phases.However,as the solidification rate increases,the discontinuous precipitation structure,modulated structures,and DO_(22) ordered phases decrease and even disappear,reducing hardness.As the solidification rate increases,after homogenization treatment,the composition and microhardness distributions of Cu-15Ni-8Sn alloy become more uniform.The time for homogenization is also shortened.It reduces production energy usage and facilitates further mechanical processing.
基金supported by "Twelfth Five Year" National Science and technology project in rural areas (2011BAD01B02-11)
文摘Based on the analysis of physical and chemical properties of soil,nutrient elements and biochemical compositions of tea leaves,the relationship between soil characters and tea quality was studied.The results showed that soil total phosphorus,potassium,available potassium,copper and zinc were the main factors which affected and limited the content of nutrient elements of tea leaves.Furthermore,soil pH,organic matter,total nitrogen,potassium,exchangeable calcium,magnesium,available copper and zinc were the main factors affecting and limiting the content of biochemical compositions in tea leaves.Tea quality could be improved by controlling these soil factors.
基金the National Natural Science Foundation(Nos.51264013 and 21005034)Science Foundation of Jiangxi Provincial Education Development(Nos.GJJ14442 and GJJ14448)the Doctoral Program of Jiangxi University of Science and Technology(No.jxxjbs13017)。
文摘Single-crystalline Mn_(3)O_(4)nanoflakes were grown on manganese sheets by one-step thermal oxidation process at 360-500℃in ambient atmosphere.The samples were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),Raman and transmission electron microscope(TEM).The nanoflakes with a size of 15-20 nm in thickness,~60 nm in width,and~210 nm in length are obtained at 360℃for 24 h.A surface diffusion mechanism is proposed to explain the growth of manganese oxide nanostructures via thermal oxidation,which includes two steps:manganese oxide(MnO/Mn_(3)O_(4))layers form firstly,and then Mn_(3)O_(4)nanostructures grow above the upper metal oxide layer to form multi-layered structures,MnO/Mn_(3)O_(4)/Mn_(3)O_(4)-nanoflakes.The nucleation and growth of Mn_(3)O_(4)nanostructures are related to the surface energy and different growth rates along different crystal directions,which are controlled by the diffusion of the metal and gas molecule.
文摘Objective To compare the short-term clinical effect and electrical parameters of His-purkinje bundle pacing(HPBP) and right ventricular inflow tract septal pacing(RVIP) in the elderly. Methods Between April 2017 and September 2019, sixty patients with indications for permanent cardiac pacing and resynchronization therapy in Beijing Anzhen Hospital were divided into the HPBP and RVIP groups, and were analyzed. A ventricular pacing lead was implanted in left ventricular septal sites with left bundle potentials or His potentials in the HPBP group. The lead was placed in right ventricular inflow tract septal sites close to distal His-bundle regions without potentials from the His-purkinje conduction system in the RVIP group. Lead impedance, R wave amplitude, pacing thresholds, QRS duration, left ventricular ejection fraction(LVEF), and left ventricular end-diastolic diameter(LVEDD), mitral regurgitation area reflux, QTc, T wave directivity, Tp-e and Tp-e/QT ratio were compared between the HPBP and RVIP groups during the procedure and the short-month follow-up. Results No significant differences were found in lead impedance, R wave amplitude, QRS duration, LVEF, LVEDD, mitral regurgitation area reflux, QTc, T wave directivity, Tp-e and Tp-e/QT ratio between the HPBP and RVIP groups. However, the pacing threshold was significantly lower in the HPBP group than in the RVIP group(0.7 ± 0.2 vs. 0.9 ± 0.3 V, P = 0.02). Conclusions The efficacy and electrical parameters of HPBP is comparable with RVIP during the procedure and the short-term follow-up.
文摘BACKGROUND The prognosis of many patients with distant metastatic hepatocellular carcinoma(HCC)improved after they survived for several months.Compared with tradi-tional survival analysis,conditional survival(CS)which takes into account changes in survival risk could be used to describe dynamic survival probabilities.AIM To evaluate CS of distant metastatic HCC patients.METHODS Patients diagnosed with distant metastatic HCC between 2010 and 2015 were extracted from the Surveillance,Epidemiology and End Results database.Univariate and multivariate Cox regression analysis were used to identify factors for overall survival(OS),while competing risk model was used to identify risk factors for cancer-specific survival(CSS).Six-month CS was used to calculate the probability of survival for an additional 6 mo at a specific time after initial diagnosis,and standardized difference(d)was used to evaluate the survival differences between subgroups.Nomograms were constructed to predict CS.Positiveα-fetoprotein expression,higher T stage(T3 and T4),N1 stage,non-primary site surgery,non-chemotherapy,non-radiotherapy,and lung metastasis were independent risk factors for actual OS and CSS through univariate and multivariate analysis.Actual survival rates decreased over time,while CS rates gradually increased.As for the 6-month CS,the survival difference caused by chemotherapy and radiotherapy gradually disappeared over time,and the survival difference caused by lung metastasis reversed.Moreover,the influence of age and gender on survival gradually appeared.Nomograms were fitted for patients who have lived for 2,4 and 6 mo to predict 6-month conditional OS and CSS,respectively.The area under the curve(AUC)of nomograms for conditional OS decreased as time passed,and the AUC for conditional CSS gradually increased.CONCLUSION CS for distant metastatic HCC patients substantially increased over time.With dynamic risk factors,nomograms constructed at a specific time could predict more accurate survival rates.
文摘Subcutaneous implantable cardioverter-defi brillator(S-ICD)therapy has become a viable alternative to conventional transvenous ICD implantation.Patients with congenitally corrected transposition of the great arteries(ccTGA)have a high risk of sudden cardiac death due to malignant arrhythmia.The interaction between the S-ICD system and the transvenous pacemaker system is not fully understood.We report a case of S-ICD implantation in a patient with ccTGA and a DDD pacemaker.The patient was a 30-year-old man with a previously placed pacemaker with diagnoses of congenital heart disease,ccTGA(SLL),left atrioventricular valve insuffi ciency,and third-degree atrioventricular block.He presented with an out-of-hospital cardiac arrest,and an S-ICD was implanted to prevent sudden cardiac death.Defi brillation checks were performed successfully.We tested the compatibility of the DDD pacemaker with the S-ICD and found that there was no interference between them.In conclusion,an S-ICD system is a reasonable and safe option in patients with ccTGA.
文摘Background:The symptomatic bradyarrhythmia is Class I indication for pacing therapy which is not a radical cure.The present study aimed to assess the feasibility and to present the initial results of the restricted ablation of the parasympathetic innervation surrounding sinus and atrioventricular(AV)nodes for treating patients with bradyarrhythmia.Methods:A total of 13 patients with cardiogenic syncope were included from May 2008 to June 2015.Under the guidance of fluoroscopy and/or three-dimensional geometry by 64-slice spiral computed tomography,atrial activation sequence in sinus rhythm was mapped.Chamber geometry was reconstructed manually or automatically using the Niobe II magnetic navigation system integrated with the CARTO-remote magnetic technology(RMT)system.Cardioneuroablation was targeted at the high-amplitude fractionated electrograms surrounding the regions of His bundle and the site with the earliest activation in sinus rhythm.Areas surrounding the sinus node,AV node,and the phrenic nerve were avoided.Results:Thirteen patients completed the studies.Ablation was successfully performed in 12 patients and failed in one.The highfrequency potential was recorded in atrial electrograms surrounding the sinus or AV nodes in all the patients and disappeared in 15 s after radiofrequency applications.The vagal reaction was observed before the improvement of the sinus and AV node function.No complications occurred during the procedures.Patients were followed up for a mean of 13.0±5.9 months.During the follow up ten patients remained free of symptoms,and two patients had a permanent cardiac pacemaker implanted due to spontaneous recurrence of syncope.The heart rate of post-ablation was higher than pre-ablation(69.0±11.0 vs.49.0±10.0 beats/min,t=4.56,P=0.008).The sinus node recovery time,Wenckebach block point,and atrium-His bundle interval were significantly shorter after ablation(1386.0±165.0 vs.921.0±64.0 ms,t=7.45,P=0.002;590.0±96.0 vs.464.0±39.0 ms,t=2.38,P=0.023;106.0±5.0 vs.90.0±12.0 ms,t=9.80,P=0.013 before and after ablation procedure,respectively).Conclusions:Ablation of sinoatrial and AV nodal peripheral fibrillar myocardium electrical activity might provide a new treatment to ameliorate paroxysmal sinus node dysfunction,high degree AV block,and vagal-mediated syncope.
