类瓷树脂及玻璃陶瓷贴面疲劳实验前后的磨耗及表面粗糙度的变化

目的:研究类瓷树脂和两种玻璃陶瓷贴面在咀嚼和温度疲劳后接触区的磨耗程度及表面粗糙度的变化,优选对临床有指导意义的贴面材料。方法:将24颗完整的离体人前磨牙预备成面中重度磨耗的形态,轴壁釉质完整、牙尖斜度20°。制作1.5 mm厚的类瓷树脂、热压铸造二硅酸锂增强型玻璃陶瓷(热压铸瓷)、计算机辅助设计/计算机辅助制造(computer-aided design/computer-aided manufacturing,CAD/CAM)切削二硅酸锂增强型玻璃陶瓷(CAD/CAM切削瓷)贴面。使用树脂粘接剂将贴面粘接到预备体面形成试件,在水中储存72 h后在咀嚼模拟疲劳机上进行模拟5年口内温度疲劳和咀嚼疲劳的实验(5~55℃冷热水循环,模拟后牙咀嚼循环120万次)。用三维激光模型扫描和数字化分析法评价疲劳实验前后贴面的磨耗程度,用三维形貌测量激光显微镜观察其表面形态及粗糙度变化。使用单因素方差分析方法对结果进行统计学分析,以P<0.05为差异有统计学意义。结果:咀嚼和温度疲劳实验后没有试件发生脱粘接或折裂。类瓷树脂组、热压铸瓷组、CAD/CAM切削瓷组的平均磨耗为(-0.13±0.03)mm、(-0.05±0.01)mm和(-0.05±0.01)mm,类瓷树脂组的磨耗量显著大于玻璃陶瓷两组(P<0.001);疲劳实验前各组接触区的表面粗糙度(Ra)为(1.24±0.20)μm、(0.75±0.09)μm、(0.73±0.14)μm,类瓷树脂组的表面粗糙度显著高于玻璃陶瓷两组(P<0.001);疲劳实验后的表面粗糙度为(1.81±0.24)μm、(1.53±0.26)μm及(1.77±0.23)μm,热压铸瓷组显著低于类瓷树脂组(P=0.005)及CAD/CAM切削瓷组(P=0.010)。结论:从磨耗速度来看,类瓷树脂贴面显著高于两种玻璃陶瓷,但更接近于对颌牙为天然牙时牙釉质的平均磨耗速度;从表面粗糙度来看疲劳实验前类瓷树脂的表面粗糙度显著高于两种玻璃陶瓷,疲劳实验后热压铸瓷贴面的表面粗糙度最低。

Effect of the Thickess on Color of Porcelain Laminate Veneer

Objective : To evaluate the color change of the two-layer porcelain laminate veneer after adding veneering porcelain of different thickness to the 0. 2 mm thick aluminum oxide. Methods : Ten aluminum oxide disks were randomized into 2 groups. Each of five disks was veneered with Vita Lumin Shade 54 porcelain of thickness 0/0.4 mm and 0. 6 mm respectively. The L'a'b* color notations of the substrate covered with nan-veneered disks and 2 thickness porcelain veneered disks were measured separately and the color differences (AE) were calculated. Results ?Statistically significant differences in color coordinates of dark substrates were recorded after the substrate was covered by an aluminum oxide disk and also after the addition of veneering porcelain to the aluminum oxide disks in group 1 (P=0. 000 2) and group 2(P=0. 007 5) and between 2 groups (P=0. 000 1). Conclusion -The ability of masking underlying discoloration was increased and shifted to gray when the thickness of veneering porcelain increased.

Immersed Interface Finite Element Methods for Elasticity Interface Problems with Non-Homogeneous Jump Conditions

In this paper,a class of new immersed interface finite element methods (IIFEM) is developed to solve elasticity interface problems with homogeneous and non-homogeneous jump conditions in two dimensions.Simple non-body-fitted meshes are used.For homogeneous jump conditions,both non-conforming and conforming basis functions are constructed in such a way that they satisfy the natural jump conditions. For non-homogeneous jump conditions,a pair of functions that satisfy the same non-homogeneous jump conditions are constructed using a level-set representation of the interface.With such a pair of functions,the discontinuities across the interface in the solution and flux are removed;and an equivalent elasticity interface problem with homogeneous jump conditions is formulated.Numerical examples are presented to demonstrate that such methods have second order convergence.

THE SCENERY FLOW FOR GEOMETRIC STRUCTURES ON THE TORUS: THE LINEAR SETTING

The authOrs define the scenery flow of the torus. The flow space is the union of all flat 2- dimensional tori of area 1 with a marked direction (or equivalently the union of all tori with a quadratic differential of norm 1). This is a 5-dimensional space, and the flow acts by following individual points under an extremal deformation of the quadratic differential. The authors define associated horocycle and translation flows; the latter preserve each torus and are the horizontal and vertical flows of the corresponding quadratic differential. The scenery flow projects to the geodesic flow on the modular surface, and admits, for each orientation preserving hyperbolic toral automorphism, an invariant 3-dimensional subset on which it is the suspension flow of that map. The authors first give a simple algebraic definition in terms of the group of affine maps of the plane, and prove that the flow is Anosov. They give an explicit formula for the first-return map of the flow on convenient cross-sections. Then, in the main part of the paper, the authors give several different models for the flow and its cross-sections, in terms of : stacking and rescaling periodic tilings of the plane; symbolic dynamics: the natural extension of the recoding of Sturmian sequences, or the S-adic system generated by two substitutions; zooming and subdividing quasi-periodic tilings of the real line, or aperiodic quasicrystals of minimal complexity; the natural extension of two-dimensional continued fractions; induction on exchanges of three intervals; rescaling on pairs of transverse measure foliations on the torus, or the Teichmuller flow on the twice-punctured torus.

Therapeutic efficacy observation on combining auricular and routine acupuncture for peripheral facial paralysis in acute stage

Objective： To investigate the clinical efficacy of combining auricular and routine acupuncture for peripheral facial paralysis in acute stage. Methods： A total of 60 eligible cases were randomly allocated into a treatment group （n=30） and a control group （n=30）. Cases in treatment group received auricular and routine acupuncture, whereas cases in the control group received routine acupuncture alone. Both groups were treated for 10 d. Results： The recovery rate was 73.3% in the treatment group and 53.3% in the control group, showing a statistical difference （P〈0.05）. Conclusion： Combining auricular and routine acupuncture is effective for peripheral facial paralysis in acute stage and has a better effect than routine acupuncture.

Clinical observation on acupoint sticking therapy plus electroacupuncture for treating peripheral facial paralysis

Objective:To observe the clinical effect of acupoint sticking therapy with Mian Tan Gao(facial paralysis paste)plus electroacupuncture(EA)for treating peripheral facial paralysis and its influence on patients'facial nerve functions,facial disability index and clinical symptoms and signs.Methods:A total of 96 peripheral facial paralysis patients were allocated into an observation group,a medicine group and an EA group by simple randomization,with 32 cases in each group.Patients in the medicine group were treated with oral mecobalamine and prednisone acetate;patients in the EA group were treated with EA on the basis of the medicine treatment;while patients in the observation group were treated with acupoint sticking therapy with Mian Tan Gao(facial paralysis paste)plus EA.After 4-week treatment,the clinical efficacy,the adverse events,and the scores of House-Brackmann(H-B)facial nerve function grading scale,visual analog scale(VAS),clinical symptoms and signs,and facial disability index(FDI)were compared.Results:After 4-week treatment,the total effective rate was 96.9%in the observation group,higher than 68.7%in the medicine group and 75.0%in the EA group(both P<0.05).After 4-week treatment,the scores of H-B grading scale,VAS and clinical symptoms and signs in the three groups dropped significantly compared with those before treatment,and the scores in the observation group were lower than those in the medicine group and EA group(all P<0.05).After 4-week treatment,the facial disability index-physical function(FDIP)in the FDI in the three groups increased significantly,with a higher value in the observation group compared with that in the medicine group and EA group(both P<0.05).The facial disability index-social function(FDIS)in the FDI dropped significantly,with a lower score in the observation group compared with that in the medicine group and EA group(both P<0.05).However,the comparisons of the items above between the medicine group and the EA group showed no statistical significance(all P>0.05).The between-group comparison of the adverse event across the three groups showed no statistical significance(P>0.05).Conclusion:Acupoint sticking therapy with Mian Tan Gao(facial paralysis paste)plus EA can decrease H-B grade,reduce pain severity and improve clinical symptoms and signs as well as the facial disability condition in peripheral facial paralysis patients.This method produced more significant efficacy compared with oral medicine and medicine plus EA.

Equality detection for linear arithmetic constraints

Satisfiability modulo theories (SMT) play a key role in verification applications. A crucial SMT problem is to combine separate theory solvers for the union of theories. In previous work, the simplex method is used to determine the solvability of constraint systems and the equalities implied by constraint systems are detected by a multitude of applications of the dual simplex method. We present an effective simplex tableau-based method to identify all implicit equalities such that the simplex method is harnessed to an irreducible minimum. Experimental results show that the method is feasible and effective.

A Comparative Study of the Local Heat Transfer Distributions Around Various Surface Mounted Obstacles

In many engineering applications,heat transfer enhancement techniques are of vital importance in order to ensure reliable thermal designs of convective heat transfer applications.This study examines experimentally the heat transfer characteristics on the base plate around various surface mounted obstacles.Local convection coefficients are evaluated in the vicinity of each individual protruding body with great spatial resolution using the transient liquid crystal technique.Five different obstacles of constant height-to-hydraulic diameter ratio(~1.3) are considered.These include:a cylinder,a square,a triangle,a diamond and a vortex generator of delta wing shape design.The experiments were carried out over a range of freestream Reynolds numbers,based on the hydraulic diameter of each obstacle,varying from 4,000 to 13,000.The results indicate a negligible effect of the flow speed on the heat transfer topological structure and a considerable effect of the obstacle geometry on the level and distribution of heat transfer enhancement.

Treatment of acne vulgaris with auricular acupoint pricking-bloodletting plus auricular point sticking therapy: a randomized controlled study

Objective: To observe the clinical efficacy of auricular point pricking-bloodletting plus auricular point sticking therapy for acne vulgaris. Methods: A total of 66 patients with acne vulgaris were randomized into an observation group and a control group by the random number table, with 33 cases in each group. The observation group was treated with auricular point pricking-bloodletting plus auricular point sticking therapy, and the control group was treated only with auricular point sticking therapy. The treatments of both groups were performed twice a week, 4 weeks as a course of treatment, for 3 courses in total. The scores of skin lesions and dermatology life quality index (DLQI) scores were recorded before and after treatment to assess the clinical efficacy. Results: During the trial, there were 3 cases of drop-out both in the observation group and the control group. After 3 courses of treatment, the total effective rate of the observation group was 96.7%, while that of the control group was 76.7%. The difference between the two groups was statistically significant (P<0.05). The intra-group comparison showed that the scores of skin lesion and DLQI were both decreased with the increase of treatment times, that was, the scores were lower than those at the previous time point (allP<0.05). After 1, 2, and 3 courses of treatment, the scores of skin lesion and DLQI of both groups were statistically different from those of the same group before treatment (allP<0.05). At every time point during the treatment, the scores of skin lesion and DLQI of the observation group were lower than those of the control group, and the differences between the two groups were statistically significant (all P<0.05). Conclusion: Auricular point pricking-bloodletting plus auricular point sticking has a better curative effect than auricular point sticking therapy alone in the treatment of acne vulgaris, and has a time-effect correlation.