Objective:To investigate influence of different atrioventricular delay(AVD) pacing on left atrial function in patients with dual chamber pacemaker implanted.Methods:A total of 40 patients with dual chamber pacemaker implanted were selected and divided into normal diastolic function group(n=20) and diastolic dysfunction group(n=20).Real-time tri-plane strain rate imaging was used to measure left atrial mean systolic peak strain rate(SRs),mean early diastolic peak strain rate(SRe) and mean late diastolic peak strain rate(SRa) under different AVDs in two groups.Results:In normal diastolic function group,influence of different AVD pacing on left atrial function was no significance(P>0.05).In diastolic dysfunction group:① When AVD increased from 80ms to 250ms,SRa increased correspondingly and reached top at 200ms AVD,then it started to decrease gradually.When AVD was 150ms and 200ms,the SRa and left atrial ejection fraction(LAEF) were significantly higher than those at 80ms,100ms and 250ms;② When AVD was 80ms and 250ms,SRs increased and SRe decreased;SRs at 200ms was significantly lower than that of AVD at 80ms [(3.02±0.56) s-1 vs.(3.27±0.62) s-1,P<0.05].Conclusion:Different atrioventricular delay has no significant effect on left atrial function in patients with normal diastolic function,but moderate prolongation of atrioventricular delay is good for left atrial function and improves hemodynamic in patients with pure diastolic dysfunction.

Objective To investigate the effect of different AV delays on left atrial function in DDD pacemaker implanted patients with diastolic dysfunction.Methods Seventy-six patients with DDD pacemaker were enrolled into the study.Patients were divided into two goups:one with normal cardiac function and the other with diastolic dysfunction.Left atrial ejection fraction (LAEF)and cardiac output (CO) were measured using echocardiography.Mean systolic peak strain rate(SR-s),mean early diastolic peak strain rate( SR-e )and mean late diastolic peak strain rate(SR-a) were measured using real-time triplane strain rate imaging.The results were compared between different AV delays.Results The group of diastolic dysfunction:①)When AV delay increased from 80 to 200 ms,LAEF 、SR-a and CO gradually increased.When AV delay increased to 200 ms,LAEF,CO,SR-a were reached to the highest level.Further increase in AV delay to 250 ms resulted in decreased SR-a,LAEF and CO.②Compared with 200 ms AV delay,SR-s increased significantly at 80 ms AV delay(P＜0.05).While in the group of normal cardiac function,insignificant changes in LAEF、SR-s、SR-e and SR-a were detected by setting AV delay.Conclusion Setting of AV delay has significant effect on the left atrial function in patients with diastolic dysfunction,and moderate prolongation of AV delay has a favorable effect.

A perfect business model could help the enterprise top others in the competition.On the basis of characteristics of the industry,building the evaluation of business model could give analysis of the feasibility and profitability as well as the risk and competitive pressure to improve its business model.

Porous polyetherimide(PEI) and polymethyl methacrylate(PMMA)/polyetherimide(PEI) nanofibers were prepared through solution electrospinning and coxial electrospinning.The effects of electropsinning parameters on the morphology and diameters of PEI and PMMA/PEI fibers were studied.The results demonstrated that porous PEI fibers with the diameters from 50 to 500 nm were obtained by electrospinning in a low concentration, while PMMA/PEI fibers with smooth surface morphology were collected using coxial electrospinning.Furthermore, the tensile strength of composite films treated under 4 MPa pressure for 10 min rose with the increasing content of PEI.

Polycarbonate (PC) nanofiber reinforced polymethyl methacrylate (PMMA) transparent composites were developed by combination of co-axial electrospinning and hot-press technique. PMMA shell and PC core composite nanofibers were obtained through the coaxial-electrospinning and the nanofiber membranes were hot pressed into PC nanofiber reinforced PMMA transparent composites. TiO2 nano-particles of different contents were introduced into the shelf (PMMA) and the core (PC) part of the composite nanofibers to shield ultraviolet transmittance of the resulting transparent composite. Distributions of the nano-particles in different parts of the core-shell structure of the composite nanofibers were observed, and the nano-particle influences of different contents and locations on visible light transmittance, ultraviolet radiation shielding and mechanical properties of the composites were analyzed. The results show that the ultraviolet radiation shielding capacity and tensile properties can be enhanced when the nano-particles are located within the shell part, with a little drop in the visible light transmittance. The nano-particles introduced into the core part induce significant improvement in mechanical performance Without Obvious impact Oil the Visible light transmittance.

Development of nanofiber reinforced transparent composites added with nano-titanium dioxide(TiO2) particles was made in this paper,in which poly(methyl methacrylate)(PMMA) acted as the matrix material.Applying the same amount of TiO2 particles either in core or in shell part of co-axially electrospun composite nanofibers,their distribution status in different parts and their influence on optical properties of the transparent composites such as visible light transparency and ultraviolet light absorbency was analyzed.Results show that the added TiO2 particles in the core part gave less influence on the visible light transparency,accompanied with an obvious absorbing peak in ultraviolet light region around wavelength of 200~400nm-1.

A variety of electrostatic spinning device are introduced.The mechanisms of single pole electrostatic spinning and dual electrode mode electrospinning are analyzed from the angle of electromagnetism.The principle of electrostatic spinning device structure and the research progress are discussed,including the Taylor cone and jet,the stability of nanometer fiber bending solution properties and the working process and the establishment of the environmental factors such as mathematical model.Finally some problems unsolved and prospect are pointed out.

A sensor of weigh in motion(WIM) sуstem for vehicles was proposed.Based on the analуsis of the communication condition,weigh-in-shaftfor vehicles,and functional principle,a 3D Finite element for the WIM sуstem was analуzed.As well as,the sensors' sensitivitу and flexible in the research projects were identified.