We introduce the concept of γ-(α, β)-open sets and the concepts of γ-(α, β)-T_i spaces(i = 0, 1, 2, 3, 4) based on the concept of(α, β)-open sets. We obtain some properties of γ-(α, β)-Tispaces. Furthermore...We introduce the concept of γ-(α, β)-open sets and the concepts of γ-(α, β)-T_i spaces(i = 0, 1, 2, 3, 4) based on the concept of(α, β)-open sets. We obtain some properties of γ-(α, β)-Tispaces. Furthermore, we study their essential characterization in topological space.展开更多
为满足管道空间位置与焊接参数相匹配的智能全位置焊接系统的工艺要求,构建了以焊接电源通信模块为从站节点的主从式CAN(Controller Area Network)总线网络控制焊接系统.提出基于PC控制的服务数据对象(ADS)通信方式访问焊接电源对象词典...为满足管道空间位置与焊接参数相匹配的智能全位置焊接系统的工艺要求,构建了以焊接电源通信模块为从站节点的主从式CAN(Controller Area Network)总线网络控制焊接系统.提出基于PC控制的服务数据对象(ADS)通信方式访问焊接电源对象词典,采用过程同步数据对象传输保证了数据传输实时性,同时使用基于视窗技术的组态软件可实现焊接过程的监视和数据的传输,实现了焊接电源CAN-open总线控制在管道全位置焊接系统的计算机集成.实验表明,该系统数据传输快速、稳定,可满足管道全位置焊接工艺要求.展开更多
随着大学英语教学改革的深入,大学英语教师应不断改进大学英语课堂教学方法。经过多年的大学英语教学实践,探索、总结出"5-Open"方法,即:Open your eyes(睁开眼睛看);Open your ears(打开耳朵听);Open your hear(t敞开心扉去...随着大学英语教学改革的深入,大学英语教师应不断改进大学英语课堂教学方法。经过多年的大学英语教学实践,探索、总结出"5-Open"方法,即:Open your eyes(睁开眼睛看);Open your ears(打开耳朵听);Open your hear(t敞开心扉去感受);Open yourmind(放飞思想去创造);Open your mouth(张开嘴巴说)。"5-Open"诠释了教师和学生在教学活动中的角色及双向、动态、互补作用,是激发学生语言学习动机、培养学生全面健康发展、提高大学英语教学效果有益的探索。展开更多
In this paper, we introduce a new class of b-open sets called Bc-open, this class of sets lies strictly between the classes of θ-semi open and b-open sets. We also study its fundamental properties and compare it with...In this paper, we introduce a new class of b-open sets called Bc-open, this class of sets lies strictly between the classes of θ-semi open and b-open sets. We also study its fundamental properties and compare it with some other types of sets and we investigate further topological properties of sets and we introduce and investigate new class of space named Bc-compact.展开更多
This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar f...This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches. Among them, 37 patients were treated using posterior open surgery, and 35 patients received mini-open operation via Wiltse approach. Crew placement accuracy rate, operative time, blood loss, postoperative drainage, postoperative hospitalization time, radiation exposure time, postoperative improvement in R value, Cobb＇s angle and visual analog scale （VAS） scores of the two methods were compared. There were no significant differences in the accuracy rate of pedicle screw placement, radiation exposure and postoperative R value and Cobb＇s angle improvement between the two groups. However, the mini-open method had obvious advantages over the conventional open method in operative time, blood loss, postoperative drainage, postoperative hospitalization time, and postoperative improvement in VAS. The mini-open pedicle screw technique could be applied in treatment of single-segment thoracolumbar fracture without neurologic injury and had advantages of less tissue trauma, short operative and rehabilitative time on the premise of guaranteed accuracy rate and no increased radiation exposure.展开更多
Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by sim...Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic initiator.The performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction condition.Urea-derived catalysts are generally superior to thiourea-derived ones.Provided with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction time.In addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.展开更多
Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polyme...Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity （1.51 ）, decreased melting temperature （218 ℃） and lower crystallinity （24.2%）. The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.展开更多
A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-ca...A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.展开更多
In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_...In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.展开更多
The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PC...The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.展开更多
Given a mapping f between continua.Let 2f and C(f) mean the induced mappings between hyperspaces.Relations are studied under the conditions:f is semi-open(almost open,respectively),2f is semi-open(almost open,respecti...Given a mapping f between continua.Let 2f and C(f) mean the induced mappings between hyperspaces.Relations are studied under the conditions:f is semi-open(almost open,respectively),2f is semi-open(almost open,respectively) and C(f) is semi-open(almost open,respectively).展开更多
文摘We introduce the concept of γ-(α, β)-open sets and the concepts of γ-(α, β)-T_i spaces(i = 0, 1, 2, 3, 4) based on the concept of(α, β)-open sets. We obtain some properties of γ-(α, β)-Tispaces. Furthermore, we study their essential characterization in topological space.
文摘为满足管道空间位置与焊接参数相匹配的智能全位置焊接系统的工艺要求,构建了以焊接电源通信模块为从站节点的主从式CAN(Controller Area Network)总线网络控制焊接系统.提出基于PC控制的服务数据对象(ADS)通信方式访问焊接电源对象词典,采用过程同步数据对象传输保证了数据传输实时性,同时使用基于视窗技术的组态软件可实现焊接过程的监视和数据的传输,实现了焊接电源CAN-open总线控制在管道全位置焊接系统的计算机集成.实验表明,该系统数据传输快速、稳定,可满足管道全位置焊接工艺要求.
文摘随着大学英语教学改革的深入,大学英语教师应不断改进大学英语课堂教学方法。经过多年的大学英语教学实践,探索、总结出"5-Open"方法,即:Open your eyes(睁开眼睛看);Open your ears(打开耳朵听);Open your hear(t敞开心扉去感受);Open yourmind(放飞思想去创造);Open your mouth(张开嘴巴说)。"5-Open"诠释了教师和学生在教学活动中的角色及双向、动态、互补作用,是激发学生语言学习动机、培养学生全面健康发展、提高大学英语教学效果有益的探索。
文摘In this paper, we introduce a new class of b-open sets called Bc-open, this class of sets lies strictly between the classes of θ-semi open and b-open sets. We also study its fundamental properties and compare it with some other types of sets and we investigate further topological properties of sets and we introduce and investigate new class of space named Bc-compact.
基金supported by the National Natural Science Foundation of China(Grant No.30973058, 81171694,and 81371968)the Program for Development of Innovative Research Team in the First Affiliated Hospital of NJMU(No.IRT-015)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This study aimed to introduce a novel mini-open pedicle screw fixation technique via Wiltse approach, and com- pared it with the traditional posterior open method. A total of 72 cases of single-segment thoracolumbar fractures without neurologic injury underwent pedicle screw fixation via two different approaches. Among them, 37 patients were treated using posterior open surgery, and 35 patients received mini-open operation via Wiltse approach. Crew placement accuracy rate, operative time, blood loss, postoperative drainage, postoperative hospitalization time, radiation exposure time, postoperative improvement in R value, Cobb＇s angle and visual analog scale （VAS） scores of the two methods were compared. There were no significant differences in the accuracy rate of pedicle screw placement, radiation exposure and postoperative R value and Cobb＇s angle improvement between the two groups. However, the mini-open method had obvious advantages over the conventional open method in operative time, blood loss, postoperative drainage, postoperative hospitalization time, and postoperative improvement in VAS. The mini-open pedicle screw technique could be applied in treatment of single-segment thoracolumbar fracture without neurologic injury and had advantages of less tissue trauma, short operative and rehabilitative time on the premise of guaranteed accuracy rate and no increased radiation exposure.
基金financially supported by the National Natural Science Foundation of China (Nos. 21734004 and 21674038)
文摘Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization(ROP)of lactones,includingδ-valerolactone,ε-caprolactone,andδ-hexalactone.The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a(thio)urea at elevated temperature under vacuum,and used in cooperation with an alcoholic initiator.The performance of the catalyst is readily adjusted and optimized through variation of the(thio)urea precursor,catalyst composition,and reaction condition.Urea-derived catalysts are generally superior to thiourea-derived ones.Provided with proper N-substituents,the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification,even at high monomer conversion and/or substantially extended reaction time.In addition to acidity,structural symmetry of the urea also proves decisive for the catalytic activity,which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.
基金supported by a grant from the National High Technology Research and Development Program of China(No.2014AA021201)the National Basic Research Program of China(No.2012CB721104)+1 种基金China Postdoctoral Science Foundation(No.2014M551574)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Star-branched polyamide 6 was prepared via anionic ring-opening polymerization of ε-caprolactam in the presence of a simple benzene-centered trifunctional activator of N,N＇,N＂-trimesoyltricaprolactam. A high polymer yields of above 95% were achieved at 160 ℃ for 15 min utilizing ε-caprolactam magnesium bromide as a catalyst. Compared with its linear counterpart, the resultant star-branched polyamide 6 showed smaller relative viscosity （1.51 ）, decreased melting temperature （218 ℃） and lower crystallinity （24.2%）. The specific properties demonstrated the existence of a star-branched structure and provided potential advantages in engineering applications.
基金financially supported by the National Natural Science Foundation of China(Nos.21574124,51503203 and51233004)
文摘A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.
基金This work was financially supported by the Special Fund for Major State Basic Research Project(G1999064801)the National Natural Science Foundation of China(Nos.20174033 and 20434020)
文摘In this paper,ring-opening polymerization of trimethylene carbonate(TMC)with rare earth(Nd,Y,La)ρ-tert- butylcalix[n]arene(n=4,6,and 8)complexes as catalysts has been studied.Poly(trimethylene carbonate)(PTMC)with M_v of 21,400 was produced by bulk polymerization under the conditions as follows:[TMC]_0/[Nd](molar ratio)=1000,80℃, 8 h.Mechanism study reveals that the polymerization proceeds via a coordination mechanism.
基金supported by the National Natural Science Foundation of China.(Grant No.20174033 and 20254001)the Special Found for Major State Basic Research Project(Grant No.G1999064801)the Committee of Science and Technology of Zhejiang Province.
文摘The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.
文摘Given a mapping f between continua.Let 2f and C(f) mean the induced mappings between hyperspaces.Relations are studied under the conditions:f is semi-open(almost open,respectively),2f is semi-open(almost open,respectively) and C(f) is semi-open(almost open,respectively).
