目的:本研究旨在探讨NT联合NIPT、早期唐氏筛查及四维超声检查在胎儿染色体疾病筛查中的临床应用价值,评估不同检测方法单独及联合使用时的检出率和诊断效能,为优化胎儿染色体异常的早期筛查策略提供依据。方法:回顾性分析2018年1月至2...目的:本研究旨在探讨NT联合NIPT、早期唐氏筛查及四维超声检查在胎儿染色体疾病筛查中的临床应用价值,评估不同检测方法单独及联合使用时的检出率和诊断效能,为优化胎儿染色体异常的早期筛查策略提供依据。方法:回顾性分析2018年1月至2024年10月于青海红十字医院行产前诊断的532例孕妇的临床数据,所有病例均行NT、NIPT、早期唐氏筛查、四维超声检查及羊水穿刺。分别计算各检测方法单独及联合筛查的阳性检出率、灵敏度、特异度、阳性预测值、阴性预测值及准确率,同时对多种检测联合方案的诊断效能进行ROC曲线分析。结果:两组孕妇的年龄、孕周、孕前BMI、居住地与文化程度均无统计学差异(P > 0.05)。单独检测中,相比NT、早期唐氏筛查及四维超声检查,NIPT具有较高的阳性检出率、灵敏度、特异度、阳性预测值、阴性预测值、准确率及AUC (P Objective: The aim of this study was to investigate the clinical application value of NT combined with NIPT, early Down’s screening, and four-dimensional ultrasonography in the screening of fetal chromosomal disorders, to assess the detection rate and diagnostic efficacy of different testing methods when used individually and in combination, and to provide a basis for optimising the early screening strategy for fetal chromosomal abnormalities. Methods: Clinical data of 532 pregnant women who underwent prenatal diagnosis in Qinghai Red Cross Hospital from January 2018 to October 2024 were retrospectively analysed, and all cases underwent NT, NIPT, early Down’s syndrome screening, four-dimensional ultrasonography, and amniocentesis. The positive detection rate, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of each test alone and in combination were calculated, and the diagnostic efficacy of the combination of multiple tests was analysed by ROC curve. Results: There were no statistically significant differences in age, gestational week, pre-pregnancy BMI, place of residence, and education between the two groups (P > 0.05). Among individual tests, compared with NT, early Down’s screening, and 4D ultrasound, NIPT alone had a higher positive detection rate, sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and AUC (P < 0.05). Compared to individual screening, NT combined with early Down syndrome screening, and NT combined with four dimensional ultrasound examination, NT combined with NIPT had higher sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and AUC (P < 0.05). Conclusion: NT combined with NIPT, early Down’s syndrome screening, and four-dimensional ultrasound can significantly improve the detection rate and diagnostic accuracy of individual screening, especially the combined NT + NIPT program has high clinical value in the screening of fetal chromosomal abnormalities, which provides a scientific basis for optimizing the screening strategy for high-risk pregnant women.展开更多
Regulatory status of drug inserts in China is described in terms of its legalsystem, administrative ramifications and existing problems. Lack of government regulatoryenforcement, industry self-control mechanisms and a...Regulatory status of drug inserts in China is described in terms of its legalsystem, administrative ramifications and existing problems. Lack of government regulatoryenforcement, industry self-control mechanisms and academic research are blamed to be the root ofthese problems. The trend of regulatory policies on the issue is outlined and suggestions on severalimportant issues are made.展开更多
Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a...Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a secondary electrode and a movable cathode were explored to improve the thickness deposition uniformity during the nickel electroforming process. Regarding these techniques, a micro electroforming system with a movable cathode was particularly developed. The thickness variation of a 16 mm×16 mm electroformed sample decreased respectively from 150% to 35%, 12% and 18% by these three techniques. Combining these validated methods, anickelmold insert for microlens array was electroformed with satisfactory mechanical properties and high replication precision. It could be applied to the following injection molding process.展开更多
A large amount of cutting heat is produced during the heavy cutting process,and insert life is restricted by the effect of thermal load.The thermal load experiment of cemented carbide SCS,WF and YT15 is carried out,an...A large amount of cutting heat is produced during the heavy cutting process,and insert life is restricted by the effect of thermal load.The thermal load experiment of cemented carbide SCS,WF and YT15 is carried out,and the results show that the bending strength and fracture toughness of cemented carbide material decrease obviously under cyclic thermal load,while in the cooling process,the material mechanical property changes worse suddenly.The high-temperature mechanical property of SCS is the most stable,and that of YT15 is the worst.Further,a relation model among cutting temperature,cutting parameters and insert life is established.Finally,the measures to improve heavy cemented carbide inserts life are summarized from the aspects of cutting parameters selection,insert optimization design and TiCN,Al2O3,TiN complex insert coating.The research results are expected to provide support and reference for heavy cutting technology and insert technology.展开更多
The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous ma...The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.展开更多
This research tests the effect of introducing turbulators of a new type into a circular tube heat exchanger under a constant and uniform longitudinal heatflux condition.A 45 mm diameter copper tube with a length of 1,3...This research tests the effect of introducing turbulators of a new type into a circular tube heat exchanger under a constant and uniform longitudinal heatflux condition.A 45 mm diameter copper tube with a length of 1,350 mm is utilized with a solid disk being inserted inside the tube,which consists of three sections,each one containing two slots.The slot is cut at a 45 degree angle toward the inner tube surface,which results in diverging theflow toward the inner hot tube surface in order to enhance the heat transfer process.Air is considered as the workingfluid with Prandtl number 0.71.The Reynolds number spans the interval from 6,000–13,500,which indicates that the consideredflow is turbulent.The heat exchanger performance is studied and analyzed in terms of average Nusselt number.The experimental results show that the Nusselt number value is directly proportional to the increase of the Reynolds number,and the number of turbulators inserts.With the use of three novel turbulators,the heat transfer was about 3.15 times higher than that in the smooth tube and the friction factor was about 1.11.展开更多
Heat augmentation techniques play a vital role in the heating and cooling processes in industries,including solar collectors and many applications that utilize heat exchangers.Several studies are based on inserting fi...Heat augmentation techniques play a vital role in the heating and cooling processes in industries,including solar collectors and many applications that utilize heat exchangers.Several studies are based on inserting fillers inside the tubes to enhance heat transfer.This investigation considered the effects of twisted tapes with large holes on a tubular heat exchanger’s(HX)heat transmission,pressure drop,and thermal boosting factor.In the experimental section,counter-swirl flow generators used twisted tapes with pairs of 1.0 cm-diameter holes and changes in porosity(Rp)at 1.30%and 2.70%.In the experiments,air was utilized as a working fluid in a tube with a circular cross-section.The turbulent flow was considered,with Reynolds numbers(Re)domain from 4800 to 9500,and a boundary condition with a uniform wall heat flux was constructed.The findings expound that when the number of holes rose,the Nusselt number(Nu),the factor of friction(f),and the thermal enhancement factor(η)all increased as well.Additionally,as the friction factor increased,the Nusselt number of the tape-equipped tube was noticeably higher.Additionally,it was discovered that the friction factor was between 70%and 94%lower than the values of the tube without tape,while the(Nu)was between 87%and 97%higher than the conventional tube values.The maximum value ofηis 89%.According to the experimental results,empirical correlations for Nu,f,andηwere also generated.展开更多
A novel ceramic cemented carbide compact insert was developed using hot pressing sintering technique. The surface layers of the sandwich material were ceramic and the middle layer was cemented carbide. The factors tha...A novel ceramic cemented carbide compact insert was developed using hot pressing sintering technique. The surface layers of the sandwich material were ceramic and the middle layer was cemented carbide. The factors that affect the properties of the compact insert were analyzed. Theoretical analyses and experiments indicated that the cemented carbide with greater elastic module and thermal expansion coefficient than ceramic should be used in the sandwich material in order to get high equivalent flexure strength and the geometric parameters of the compact insert are also important to its properties.展开更多
文摘目的:本研究旨在探讨NT联合NIPT、早期唐氏筛查及四维超声检查在胎儿染色体疾病筛查中的临床应用价值,评估不同检测方法单独及联合使用时的检出率和诊断效能,为优化胎儿染色体异常的早期筛查策略提供依据。方法:回顾性分析2018年1月至2024年10月于青海红十字医院行产前诊断的532例孕妇的临床数据,所有病例均行NT、NIPT、早期唐氏筛查、四维超声检查及羊水穿刺。分别计算各检测方法单独及联合筛查的阳性检出率、灵敏度、特异度、阳性预测值、阴性预测值及准确率,同时对多种检测联合方案的诊断效能进行ROC曲线分析。结果:两组孕妇的年龄、孕周、孕前BMI、居住地与文化程度均无统计学差异(P > 0.05)。单独检测中,相比NT、早期唐氏筛查及四维超声检查,NIPT具有较高的阳性检出率、灵敏度、特异度、阳性预测值、阴性预测值、准确率及AUC (P Objective: The aim of this study was to investigate the clinical application value of NT combined with NIPT, early Down’s screening, and four-dimensional ultrasonography in the screening of fetal chromosomal disorders, to assess the detection rate and diagnostic efficacy of different testing methods when used individually and in combination, and to provide a basis for optimising the early screening strategy for fetal chromosomal abnormalities. Methods: Clinical data of 532 pregnant women who underwent prenatal diagnosis in Qinghai Red Cross Hospital from January 2018 to October 2024 were retrospectively analysed, and all cases underwent NT, NIPT, early Down’s syndrome screening, four-dimensional ultrasonography, and amniocentesis. The positive detection rate, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of each test alone and in combination were calculated, and the diagnostic efficacy of the combination of multiple tests was analysed by ROC curve. Results: There were no statistically significant differences in age, gestational week, pre-pregnancy BMI, place of residence, and education between the two groups (P > 0.05). Among individual tests, compared with NT, early Down’s screening, and 4D ultrasound, NIPT alone had a higher positive detection rate, sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and AUC (P < 0.05). Compared to individual screening, NT combined with early Down syndrome screening, and NT combined with four dimensional ultrasound examination, NT combined with NIPT had higher sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and AUC (P < 0.05). Conclusion: NT combined with NIPT, early Down’s syndrome screening, and four-dimensional ultrasound can significantly improve the detection rate and diagnostic accuracy of individual screening, especially the combined NT + NIPT program has high clinical value in the screening of fetal chromosomal abnormalities, which provides a scientific basis for optimizing the screening strategy for high-risk pregnant women.
文摘Regulatory status of drug inserts in China is described in terms of its legalsystem, administrative ramifications and existing problems. Lack of government regulatoryenforcement, industry self-control mechanisms and academic research are blamed to be the root ofthese problems. The trend of regulatory policies on the issue is outlined and suggestions on severalimportant issues are made.
基金Projects(51305465,91123012)supported by the National Natural Science Foundation of China
文摘Thickness deposition is a crucial issue on the application of electroformed micro mold inserts. Edge concentration effect is the main source of the non-uniformity. The techniques of adopting a non-conducting shield, a secondary electrode and a movable cathode were explored to improve the thickness deposition uniformity during the nickel electroforming process. Regarding these techniques, a micro electroforming system with a movable cathode was particularly developed. The thickness variation of a 16 mm×16 mm electroformed sample decreased respectively from 150% to 35%, 12% and 18% by these three techniques. Combining these validated methods, anickelmold insert for microlens array was electroformed with satisfactory mechanical properties and high replication precision. It could be applied to the following injection molding process.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51205095)Support Program for Key Youth(Grant No.1154G39)
文摘A large amount of cutting heat is produced during the heavy cutting process,and insert life is restricted by the effect of thermal load.The thermal load experiment of cemented carbide SCS,WF and YT15 is carried out,and the results show that the bending strength and fracture toughness of cemented carbide material decrease obviously under cyclic thermal load,while in the cooling process,the material mechanical property changes worse suddenly.The high-temperature mechanical property of SCS is the most stable,and that of YT15 is the worst.Further,a relation model among cutting temperature,cutting parameters and insert life is established.Finally,the measures to improve heavy cemented carbide inserts life are summarized from the aspects of cutting parameters selection,insert optimization design and TiCN,Al2O3,TiN complex insert coating.The research results are expected to provide support and reference for heavy cutting technology and insert technology.
文摘The design of the flow field is highly responsible for the performance of the Proton Exchange Membrane Fuel Cell (PEMFC). In this study, pin type flow channel is numerically analyzed by arranging carbon made porous material in uniform and zigzag manner on the rib surface of the flow field. The study focuses on enhancing the performance of PEMFC by reducing liquid flooding in the interface between the rib and Gas Diffusion Layer (GDL). A single PEMFC having an active area of 25 cm2, with three flow channel designs (conventional serpentine, pin type flow channel with 2 mm cubical porous inserts in zigzag and uniform pattern) are modeled for the numerical analysis. The effect of porosity of the carbon inserts on the cell performance is studied by varying its value from 0.6 to 0.9. The results show that the performance of the flow channel with zigzag and uniformly positioned porous inserts is more than the conventional serpentine flow channel by 20.36% and 16.87% respectively. The reason for this increase is the removal of the accumulated water from the rib surface due to the capillary action of the porous carbon inserts. This helps in eliminating the stagnant water regions under the rib and thereby helps in reducing liquid flooding.
文摘This research tests the effect of introducing turbulators of a new type into a circular tube heat exchanger under a constant and uniform longitudinal heatflux condition.A 45 mm diameter copper tube with a length of 1,350 mm is utilized with a solid disk being inserted inside the tube,which consists of three sections,each one containing two slots.The slot is cut at a 45 degree angle toward the inner tube surface,which results in diverging theflow toward the inner hot tube surface in order to enhance the heat transfer process.Air is considered as the workingfluid with Prandtl number 0.71.The Reynolds number spans the interval from 6,000–13,500,which indicates that the consideredflow is turbulent.The heat exchanger performance is studied and analyzed in terms of average Nusselt number.The experimental results show that the Nusselt number value is directly proportional to the increase of the Reynolds number,and the number of turbulators inserts.With the use of three novel turbulators,the heat transfer was about 3.15 times higher than that in the smooth tube and the friction factor was about 1.11.
文摘Heat augmentation techniques play a vital role in the heating and cooling processes in industries,including solar collectors and many applications that utilize heat exchangers.Several studies are based on inserting fillers inside the tubes to enhance heat transfer.This investigation considered the effects of twisted tapes with large holes on a tubular heat exchanger’s(HX)heat transmission,pressure drop,and thermal boosting factor.In the experimental section,counter-swirl flow generators used twisted tapes with pairs of 1.0 cm-diameter holes and changes in porosity(Rp)at 1.30%and 2.70%.In the experiments,air was utilized as a working fluid in a tube with a circular cross-section.The turbulent flow was considered,with Reynolds numbers(Re)domain from 4800 to 9500,and a boundary condition with a uniform wall heat flux was constructed.The findings expound that when the number of holes rose,the Nusselt number(Nu),the factor of friction(f),and the thermal enhancement factor(η)all increased as well.Additionally,as the friction factor increased,the Nusselt number of the tape-equipped tube was noticeably higher.Additionally,it was discovered that the friction factor was between 70%and 94%lower than the values of the tube without tape,while the(Nu)was between 87%and 97%higher than the conventional tube values.The maximum value ofηis 89%.According to the experimental results,empirical correlations for Nu,f,andηwere also generated.
文摘A novel ceramic cemented carbide compact insert was developed using hot pressing sintering technique. The surface layers of the sandwich material were ceramic and the middle layer was cemented carbide. The factors that affect the properties of the compact insert were analyzed. Theoretical analyses and experiments indicated that the cemented carbide with greater elastic module and thermal expansion coefficient than ceramic should be used in the sandwich material in order to get high equivalent flexure strength and the geometric parameters of the compact insert are also important to its properties.
