TREATMENT OF OBSTINATE PEPTIC ULCER AND CHRONIC GASTRITIS WITH A METAL RING EMBEDDED IN ZUSANLI ACUPOINT

We had treated 102 cases of obstinate peptic ulcer and chronic gastritis with ametal ring embedded in Zusanli acupoint since October 1989 to October 1992,and got satisfactorytherapeutic effects.The total effective rate is 96.08%,the cure rate of peptic ulcer is 87.32%,therecurrence rate is significantly lower than that of control group(P【0.001),and it has no side-effect.

A new level-shifting structure with multiply metal rings by divided RESURF technique

A new structure of a lateral n-MOST and a new level-shifting structure with multiply metal rings （MMRs） by divided RESURF technique have been proposed. The device and electrical performances of the structure are analyzed and simulated by MEDICI. In comparison to the level-shifting structure with multiply floating field plates （MFFPs） used before, the structure stated here improves the reliability and diminishes the voltage difference between the voltage of the power supply of the high-side gate driver and the voltage of the output terminal of the level-shifting structure, which is also that of the input terminal of the high-side gate driver. The maximal voltage difference of the level-shifting structure in this paper is 30% lower than that used before. Therefore, good voltage isolation and current isolation are obtained. The structure can be used in the level-shifting circuit of various applications.

Stress and thickness calculation of a bolted flat cover with double metal sealing rings

The design of a bolted flat cover is extremely important for the structural integrity of pressure vessels.The present design codes provide the thickness calculation equations for a bolted flat cover with single metal gasket.However,the rules for a bolted flat cover with double metal sealing rings are not developed to date.In the study,a new thickness calculation equation for the bolted flat cover with double metal sealing rings is proposed.First,the theoretical stress solution for bolted flat cover with the double metal sealing rings is obtained,based on the theory of simply supported circular plate and then verified using the results from finite element analyses.The results indicate that the influence of double metal sealing ring on the stress of the flat cover is more serious compared to single metal gasket.Second,a more accurate and reasonable equation is proposed to calculate the thickness of bolted flat cover with double metal sealing rings based on the derived theoretical equations of maximum stress.Finally,the influence of linear load and the spacing between rings on the thickness are discussed.Subsequently,a few suggestions are provided to design low-pressure or atmosphere pressure vessels.The study provides a theoretical foundation to develop design codes of pressure vessels in nuclear reactors.

Calcium chloride doped zinc-cobalt metal-cyanide complex:Unexpected highly activity towards ring-opening polymerization of propylene oxide

高度活跃的钙氯化物(CaCl2 ) 做了 Zn-CoIII 双金属氰化物(Ca 直接数字控制) 催化剂第一被报导。Ca 直接数字控制介绍了很更高的聚合物收益(> 54 kg polymer/g 催化剂) 在相对低温度(80 鈥 ? 15 掳 C ) 向丙烯氧化物(PO ) 的戒指洞聚合(ROP ) 比没有修正，做了直接数字控制催化剂。

具有圆度误差的径向金属密封接触应力研究

由于加工圆度误差的影响,井下流量控制阀径向金属密封接触应力分布不均匀,从而影响密封性能。利用有限元方法研究具有圆度误差的径向金属密封唇部接触应力分布,并分析圆度误差对径向金属密封接触应力的影响;基于有限元分析结果提出径向金属密封接触应力分布的理论解析式,并进行误差分析。具有圆度误差的径向金属密封唇部接触应力分布的理论解与数值解相符,各参数引起的最大接触应力的平均相对误差约为10%。根据具有圆度误差的径向金属密封副接触应力的分布规律,提出合理的过盈量函数,修正了径向金属密封轴对称结构的悬臂梁模型的接触应力理论关系式,得出了圆度误差下的径向金属密封接触应力分布规律。研究结果为井下流量控制阀径向金属密封的设计提供了理论指导。

铋/锡催化L-丙交酯与乙交酯本体开环共聚

为探究金属催化剂辛酸亚锡(Sn(Oct)_(2))与次水杨酸铋(BiSS)对L-丙交酯(L-LA)与乙交酯(GA)本体开环聚合(ROP)反应过程及产物性能的影响,使用不同含量的Sn(Oct)_(2)或BiSS合成一系列聚丙交酯-乙交酯共聚物(PLGA)。通过核磁共振波谱仪、傅里叶变换红外光谱仪、凝胶渗透色谱仪对聚合物的微观结构、聚合反应动力学和相对分子质量进行了表征,借助热重分析仪和差示扫描量热仪对聚合物的热性能进行了分析。结果表明,BiSS是一种非常有吸引力的催化剂,在ROP制备PLGA共聚物中获得了与Sn(Oct)_(2)类似的结果,其催化性能可与Sn(Oct)_(2)相媲美。BiSS催化制备的PLGA的热稳定性显著提高,例如,1000×10^(-6)Bi催化制备的PLGA73在氮气氛围下的T_(5)%和T_(90)%分别为269.6℃和379.2℃,相较于Sn(Oct)_(2)分别升高了36℃和82.7℃。由BiSS催化制备的PLGA链段具有更高的随机性和更短的L-LA序列长度。BiSS可以替代商业使用的Sn(Oct)_(2)用于生产生物医学领域应用的低毒性PLGA。

聚酯合成催化技术的研究进展

聚酯工业的进步离不开先进的催化技术。本文对聚酯合成催化体系的研究进展进行了评述。着眼于目前占主导的金属催化剂,对锑、钛、锡、锗、铝等催化剂在活性、副反应等方面所开展的金属复合、配体改性、载体负载等工作进行了总结,介绍了有机物、离子液体、酶等非金属催化体系的研究进展,并对促进聚酯合成的电、光、微波等催化辅助技术进行了评述。催化能力强、副反应少、聚合条件温和催化体系的开发有助于聚酯品质的提升,将先进的表征手段、模型研究以及聚酯构效关系规律探索结合到催化体系的研究中,可加速高效聚酯催化技术的研发。

Successful removal of a penoscrotal constricting ring in a 49-year-old male

Placement of constricting devices around the penis and scrotum for autoerotic purposes or increasing sexual performance represents a well-known challenge for urologists and can result in serious complications.The removal of the constricting devices can be challenging and often requires resourcefulness and multidisciplinary approach.We report one case of successful removal of a penoscrotal constricting metal ring in a 49-year-old male using a handheld orthopaedic saw under ketamine and midazolam sedation in the emergency department.

波导谐振环微带阵列多裂纹检测传感器设计

针对飞行器机翼的大面积壁板等金属结构的多形态裂纹分布难以同时检测、检测精度低等问题,设计了一种互补开口波导谐振环微带阵列多裂纹检测传感器。该传感器群阵列中不同尺寸的互补开口波导谐振环微带传感器能够检测直裂纹、针孔、星型3种裂纹的特征参数。实验结果表明,传感器对3种裂纹的参数变化的最大检测灵敏度达到了150 MHz/mm,传感器可检测出的最小直裂纹尺寸为10 mm×1 mm×0.1 mm。该传感器结合了互补开口谐振环辐射能力强、易于表面共形和基片集成波导低损耗、品质因数高、尺寸小的特性,能够实现对金属材料上多形态裂纹的同时检测,具有灵敏度高、检测范围大等优点。

Metal Sealing Performance of Subsea X-tree Wellhead Connector Sealer

The metal sealing performance of subsea X-tree wellhead connectors is crucial for the safety and reliability of subsea X-trees. In order to establish the theoretical relation between metal sealing ring＇s contact stress and its structural parameters and working pressure, a mechanical analysis method for double-cone sealing of high pressure vessels is applied in analyzing the metal sealing ring under the condition of preload and operation. As a result, the formula of the unit sealing load for the metal sealing ring under operation with residual preload is shown in this paper, which ensures that the metal sealing ring has an excellent sealing effect and can prevent the metal sealing ring from yielding. Besides, while analyzing the sealing process of the metal sealing ring, the change rule of contact stress and working pressure is concluded here, putting forward that the structural parameters of the metal sealing ring are the major factors affecting the change rule. Finally, the analytical solution through theoretical analysis is compared with the simulation result through finite element analysis in a force feedback experiment, and both are consistent with each other, which fully verifies for the design and calculation theory on metal sealing ring＇s contact stress and its structural parameters and working pressure deduced in this paper. The proposed research will be treated as an applicable theory guiding the design of metal seal for subsea X-tree wellhead connectors.

Finite Element Optimization of Vee-ring Factor in Fine-blanking Process

The vee-ring is one of the most characteristic features of the fine-blanking process which is derived from the conventional blanking. With the vee-ring, a counter plate and some other working parameters, a component with a precise geometry and smoothly blanked surface can be produced without any major secondary operations. However, these working parameters are always empirically determined or determined by trial-and-error method, which is time-consuming and expensive. In this study, a numerical simulation method was used to analyze the effect of vee-ring factors on product quality, such as distance between vee-ring and punch, vee-ring height and blank holder force, so as to obtain as high clean cut ratio as possible. During the simulation, the model was assumed as axisymmetric one and the workpiece was considered as rigid plastic material, meanwhile the tools were defined as rigid bodies so as to shorten the computational time. A damage model taking into account the influence of hydrostatic stress was used to simulate material fracture in fine-blanking. The result obtained from the simulation indicated that with the help of vee-ring, the metal material near the shear band does not flow with the punch penetration and high compressive stress in the shear band is generated. Consequently, higher clean cut ratio can be obtained with a vee-ring model than the one obtained with a plane blank holder model. Furthermore, the longer the distance between vee-ring and punch is, the higher the height of roll-over becomes.

Al(HSO_4)_3/silica gel as a novel catalytic system for the ring opening of epoxides with thiocyanate anion under solvent-free conditions

For the first time,metal hydrogen sulfates and phosphates/silica gel have been studied as efficient and powerful solid acid catalysts in the ring opening of epoxides with thiocyanate anion.The most significant result was obtained by Al(HSO4)3/SiO2which afforded the corresponding β-hydroxy thiocyanates under mild reaction conditions and in very short reaction times.The cheapness, availability of the catalyst,ease of procedure and work-up make this method attractive for the organic synthesis.

Tree ring analysis for determination of pollution history of Chengde City，north China

Air pollution history of sulphur and heavy metals since 1800 in Chengde City , north China,was studied by analyzing the concentrations of sulphur and heavy metals in growth rings of Pinus tabulaeformis Carr. Sulphur concentrations in the tree rings of 1910-1920, 1970-1980,and 1980-1990 have increased 1-2 , 3-5 and 10 times respectively as those in the tree ring of 1810-1820 (P<0. 05). This is ascribed to the result of urbanization, especially the appearance and aggravation of industrialization, in the city of Chengde since 1950s. Fe appeared to increase during 1920-1940, possibly due to the opening of Damiao Iron Mine by the Japanese in 1927; Mn increased throughout the whole history, from 4. 1 μg/g(1840- 1850) to 10. 4 μg/g (1980 1990,P <0. 05);Pb did not increase until 1980 but increased sharply during the last 10 years by 560%(P<0. 001). This is caused by the increased number of automobiles in the city. The contents of Cu,Zn, Ni have changed little. The concentrations of sulphur and heavy metals in the tree rings at the beginning of 1800s were the lowest and could be regarded as the background concentrations.We calculated that S, Fe, Pb, Mn, Ni, and Zn in the tree rings have increased 10, 2.4,1.8,1.5,1.0 and 0. 8 times respectively during the past 190 years or so. The results showed that serious environmental pollution, especially air pollution of SO2,has occurred since 1949 when the People's Republic of China was founded.

基于虚拟制备的大环径比O形金属橡胶密封件结构性能研究

金属橡胶密封件(MRS)作为一种新型轻质弹性金属结构,可以替代传统聚合物材料密封件在极端环境中使用。但由于MRS结构的复杂与制备工艺的繁琐,MRS结构特性与力学性能无法精确设计而影响了工程应用。针对这一不足,基于计算机仿真技术,对大环径比O形MRS的制备工艺流程进行数值模拟,采用虚拟制备构建可以真实反映MRS宏观力学性能及微观复杂结构的模型,并依据实际工况对MRS不同压缩工况下的模型进行静力学仿真分析,分析压缩率对于密封系统摩擦界面的接触特性及其结构响应的影响,结果表明其接触特性受到压缩工况及包覆层塑性失效的共同作用。以静力学仿真输出的细观接触应力为参量,结合间隙流动模型,对密封件泄漏率进行仿真和计算,分析其泄漏率的影响因素,结果表明在密封件不发生塑性失效的前提下,较大的压缩率可以减少泄漏。研究结果对新型宽温域密封件的参数设计、性能研究与推广应用有一定的指导意义。

钴铜混合离子-DC^(-)凝胶体系有序结构的FTIR研究

在体外模拟胆结石形成机制的体系,选取混合金属离子Co^(2+)和Cu^(2+)研究其相互耦合,考察Co^(2+)/Cu^(2+)-DC^(-)凝胶体系有序结构的特征,分别用扫描仪及体式显微镜记录体系产生的沉淀的时空图案;傅里叶变换红外谱从凝胶中剥离的沉淀的微观结构。结果显示:Co^(2+)和Cu^(2+)存在相互影响,其混合离子-DC^(-)凝胶体系的沉淀物的时空图案与其单一离子-DC^(-)凝胶体系不同,Co^(2+)-DC^(-)凝胶体系沉淀形貌特征为以粉色花状分形形成周期环;Cu^(2+)-DC^(-)凝胶体系沉淀形貌特征为以蓝色球形颗粒形成周期环;混合金属离子Co^(2+)/Cu^(2+)-DC^(-)凝胶体系沉淀形貌更具复杂性:浅蓝色颗粒组成花状分形再以周期环分布、浅粉色花状分形的枝杈存在颗粒形态分布。FTIR光谱显示,混合离子Co^(2+)/Cu^(2+)-DC^(-)凝胶体系多种沉淀物为Co^(2+),Cu^(2+)-DC^(-)双核配合物,具有非化学计量特征。

航天飞行器用高温密封测试技术研究

航天飞行器用高温密封的工作环境苛刻,为保障飞行安全需进行密封件性能测试,然而现有的测试设备和方法无法达到理想的高温高压且可变的模拟工作环境。以W形金属密封圈气密性测试为例,设计密封件试验器并搭建高温热密封试验平台;对试验器模型进行瞬态热分析,得到试验器温度场分布和结构总变形;完成W形金属密封圈从室温至740℃的多种温度、0~1.2 MPa内外压差工况下的连续、自动化的泄漏率测试。结果表明:试件在试验器内受热均匀,可达到要求的最高温度740℃,试验器可承受1.1 MPa内压,在高温工况下无塑性变形;提出的测试技术可有效判定不同W形金属密封圈的密封性能优劣,可实现W形密封件在多种压差、温度工况的气密性测试。

汽车排气管V形金属密封环设计与优化

针对汽车排气管密封问题,设计一种适合汽车排气系统密封的V形金属密封环。该密封环采用平面接触、小接触压力方式,在满足密封要求的同时避免了较大的预紧力;在波谷处采用圆弧过渡,降低了密封环的整体刚度,侧边倾斜一定角度以增大密封环的回弹性能。利用ANSYS Workbench软件对V形金属密封环常温预紧和高温工况下的密封性能进行分析,在保证密封强度要求下确定安装时合适的轴向压缩量;分析密封环结构参数对密封性能的影响,发现壁厚、环宽、波谷半径、接触圆半径、开口角度对密封性能影响较大。基于Design-Expert软件对密封环结构参数进行多目标优化,从而降低了密封环最大等效应力,提高了最大接触压力,减小了密封环质量,并通过相关实验验证有限元模型的可靠性。

Using Neural Network to Predict the Interfacial Friction and Flow Stress of Materialsvia Ring Compre

In this study a neural network approach is proposed to realize an automatic numerical prediction of the interfacial friction factor and the flow stress of materials. Decrease in the inner diameter and reduction in the height of the ring are taken as input

Simulation and Analysis of Ring Compression Using RP/RVP Meshless Method

To avoid mesh distortion and iterative remeshing in mesh-based numerical analysis,a meshless approach based on element free Galerkin (EFG) method is applied to the metal forming analysis of ring compression. Discrete equations are formulated upon the moving least-squares (MLS) approximation and modified Markov variational principles for rigid-plastic/ rigid-viscoplastic (RP/RVP) material models. The penalty function is used for the incompressible condition without volumetric locking. Based on the axisymmetric mechanical model,ring tests with different friction coefficients are studied. The deformed nodal configurations and shaded contours of equivalent strains are shown by developed meshless post processor. The comparison of meshless and finite element (FE) results validates the feasibility and accuracy for meshless method to simulate metal forming process.