电粘油的新发展

电粘油(Electrorheological fluid)是一种粘度受周围电场变化而改变的液体。从英语字面讲,叫电-流变的液体,即粘度受电的影响而改变的液体。它在强电场作用下,可在一秒钟内从液态变成固态,再由固态变成液态2000次,从而有可能利用这种快速改变的特性使一个没有运动件的阀去控制一些机械运动,如离合器、制动器、避震器。

水冷双极不粘电凝辅助下全麻扁桃体剥离术56例临床体会

目的探讨水冷双极不粘电凝辅助下全麻扁桃体剥离术与传统全麻扁桃体剥离术的效果比较。方法比较应用水冷双极不粘电凝辅助下全麻扁桃体剥离术56例患者与传统组扁桃体剥离术48例患者的术中平均出血量和平均手术时间。结果电凝辅助组术中平均出血量(7.3±1.1)mL,平均手术时间(10.8±1.7)min;传统组术中平均出血量(38.4±1.5)mL,平均手术时间(24.2±3.2)min,差异有高度统计学意义。结论水冷双极不粘电凝辅助下全麻扁桃体剥离术较传统全麻扁桃体剥离术,术中出血少、手术时间短。

不粘双极电凝在扁桃体切除术中的应用

目的:通过比较采用不粘双极电凝器与传统的剥离法实施扁桃体切除术的手术效果,探讨不粘双极电凝器在扁桃体切除术中的应用效果。方法:治疗组29例和对照组32例慢性扁桃体炎患者分别采用不粘双极电凝器和传统剥离法施行扁桃体切除术。结果:用不粘双极电凝器行扁桃体切除术,较传统的剥离法实施扁桃体切除术手术时间短,术中出血少,术后并发症发生率低,患者痛苦轻。结论:用不粘双极电凝器施行扁桃体切除术能缩短手术时间,减少术中术后出血,疗效安全可靠,值得临床推广。

外加电场作用下水驱油藏的油水相对渗透率

用非稳定法油水相对渗透率测定实验研究了外加直流电场对水驱油藏的油水相对渗透率的影响。结果表明:外加直流电场下岩心水湿性增强,束缚水饱和度增大,残余油饱和度降低,油相相对渗透率增大,水相相对渗透率降低,影响这种渗透率变化的因素有油相和水相的渗流特性、油藏壁面的双电层结构以及油藏中原油的电粘效应等。10 V/cm正向电场作用时水驱采收率提高约10%;7 0 V外加电压下,45°C原油在剪切速率0 036 s-1时的视粘度由771 mPas降至310mPas,这对油层中原油流动十分有利。

粘度法研究SDS与PEO之间的相互作用

采用粘度法测定了不同温度下 ( 2 98 1 5K ,30 8 1 5K ,31 8 1 5K)阴离子表面活性剂十二烷基硫酸钠 (SDS)—水溶性聚合物聚氧乙烯 (PEO)体系在有无电解质 (NaOH)存在时溶液的宏观粘度 ,研究了SDS—PEO体系分子间相互作用对PEO构型的影响 ,得到了不同SDS—PEO体系的临界聚集浓度 (CAC)和聚合物饱和浓度 (PSP) ,并根据表面活性剂—聚合物体系相互作用模型计算了SDS胶束被吸附到聚合物PEO过程的吉布斯函数变 ,讨论了SDS—PEO体系分子间相互作用强度 结果表明 ,在所研究范围内 ,SDS—PEO体系有无电解质溶液的比浓粘度均随聚合物PEO浓度的减小而急剧升高 ,呈现典型的聚合电解质行为 ,而且SDS的浓度越大 ,电粘效应愈明显 由此可以推断 ,聚合物PEO与表面活性剂SDS之间主要是通过疏水键相互结合 ,PEO分子链处于更伸展的状态 NaOH的存在使聚合物PEO分子与胶束结合位置减少 ,聚集体的体积减小 ,或者介电常数增大 ,因此表现出电粘效应弱于不含碱的表面活性剂—聚合物体系 。

电场致流变流体研究进展

综述电场致流变流体在制备、机理和应用前景等方面的研究进展。

蒙脱土悬浮液体系流变性研究

研究了Na-蒙脱土和Ca-蒙脱土在不同含量下形成悬浮液体系的流变特性。试验结果表明,Na Mt和Ca Mt悬浮液体系的流变模型遵循幂律方程,且Na Mt悬浮液体系比Ca Mt具有良好的结构粘度和触变性结构。电粘作用是带电悬浮液体系具有非牛顿流体特性的一个主要因素,且悬浮体系的流变性与界面电导率和热动力学有关。蒙脱土悬浮液体系的粘性变化、结构触变性以及流变模型的建立,为评价、预测和改变涂料工艺性能提供试验依据。

Preparation and characterization of diamond film on Cu substrate using Cu-diamond composite interlayer

Large area diamond films were fabricated on copper substrates by a multi-step process comprised of electroplating Cu-diamond composite layer on Cu substrate, plating a Cu layer to fix the protruding diamond particles, and depositing continuous diamond film on composite interlayer by hot-filament chemical vapor deposition （HFCVD）. The interface characteristics, internal stress and adhesion strength were investigated by scanning electron microscopy, Raman analysis and indentation test. The results show that the continuous film without cracks is successfully obtained. The microstructure of the film is a mixture of large cubo-octahedron grains grown from homo-epitaxial growth and small grains with （111） apparent facets grown from lateral second nuclei. The improved adhesion between diamond film and substrate results from the deep anchoring of the diamond particles in the Cu matrix and the low residual stress in the film.

Electro-flotation and collision-attachment mechanism of fine cassiterite

In order to discuss the particle-bubble interaction during the electro-flotation of cassiterite,the recovery of cassiterite with different particle sizes was investigated,and the collision mechanism between the cassiterite particles and H2 bubbles was explored.The flotation tests were carried out in a single bubble flotation cell.The results show that cassiterite particles 10 μm,10-20 μm,20？38 μm and 38-74 μm match with bubbles with size of 50-150 μm,about 250 μm,74 μm and 74 μm,respectively,and a better recovery can be obtained.It is demonstrated that the recovery of cassiterite is influenced by the size of cassiterite particles and bubbles.Furthermore,the probabilities of collision,adhesion,detachment and collection were calculated using the collision,attachment and collection models.Theoretical calculation results show that the collision probability decreases sharply with decreasing particle size and increasing bubble size（below 150 μm）.The attachment probability would increase from the effective collision,leading to the increase of recovery.

NH_2（CH_2）_2NH（CH_2）_3Si（OEt）_3／SiO_2ER流体的流变特性

研究用二氧化硅负载ｎ－β（氨乙基）－γ（氨丙基）三乙氧基硅烷［ＮＨ２（ＣＨ２）２ＮＨ（ＣＨ２）３Ｓｉ（ＯＥｔ）３］作为分散颗粒制备的电流变（ＥＲ）流体的流变行为。结果发现，流体具有宾汉流体的特点。以硅油为分散介质，含２０％（Ｗ／Ｖ）分散颗粒的流体，不添加任何活化剂，在剪切速率（ｒ）为８．０６６ｓ－１时，电场强度（Ｅ）从０升至１．５０ｋＶ／ｍｍ，表观粘度（ηａ）从０．３５Ｐａ·ｓ增大到２６．５Ｐａ·ｓ。ｒ提高，ηａ降低。改变电场强度、分散颗核含量、分散介质种类和添加极性分子，可以改变流体的剪切应力和表观粘度，但不能改变流型。

Sliding electrical contact behavior of AuAgCu brush on Au plating

The sliding electrical contact behavior of AuAgCu brush on Au plating was investigated at various normal loads and sliding speeds.The contact voltage drop and electrical noise between the two brushes were measured and the resistance waveforms were recorded.The morphologies of the worn surfaces and wear debris of the brush and plating were observed.The results show that the contact voltage drop and electrical noise decrease with the addition of load whereas increase drastically with increasing sliding speed.With the electrical current in vacuum,the wear process of AuAgCu brush on Au plating involves adhesion,transfer of gold from the plating to the brush,rolling of wear debris between contact surfaces and arc-induced melt at the contact edge,and this gold-on-gold sliding electrical contact system is reliable within experiment period.

Analysis of the Test of ER Fan Clutch

Aim To carry out an experiment of the application of ER fluids in the clutch by reforming a fan clutch used in a truck. Methods At three different input rotating speeds,when the strength of applied electric field was changed, the output rotating speeds were recorded and analyzed. Results By comparing the results got under different experimental procedures with those measured with an electro-rheometer, it can be seen that the shearing rate has tremendous influence on the speed modulating of a fan clutch. This is because the disperse phase can't form chains (clusters)easily at high shear rate.Conclusion The result tested on the present ER fluid demonstrates that this fluid will show the properties of Newton one,i.e. its apparent viscosity is constant. as the shear rate increases.

A Novel Capacitive Pressure Sensor

A novel capacitive pressure sensor is presented, whose sensing structure is a solid-state capacitor consisting of three square membranes with Al/SiO2/n-type silicon. It was fabricated using pn junction self-stop etching combined with adhesive bonding,and only three masks were used during the process. Sensors with side lengths of 1000,1200,and 1400μm were fabricated,showing sensitivity of 1.8,2.3, and 3.6fF/hPa over the range of 410～ 1010hPa, respectively. The sensi- tivity of the sensor with a side length of 1500μm is 4. 6fF/hPa,the nonlinearity is 6. 4% ,and the max hysteresis is 3.6%. The results show that permittivity change plays an important part in the capacitance change.

Design and Optimization of Electromagnetic Ultrasonic Body Wave Probe Based on Halbach Structure

A shear wave electromagnetic acoustic transducer(EMAT)optimized structure is proposed by using circumferential annular Halbach magnet structure.Based on the orthogonal test,the effects of the coil conductor width,the spacing between adjacent conductors,the number of turns and the lifting distance on EMAT energy conversion effect are studied,and the optimal parameter combination is given.The structural design of the Halbach magnet is proposed.The cost coefficient S of the Halbach structure is defined,and the optimal thickness of auxiliary magnetic pole is obtained.The optimized EMAT coil diameter is reduced by 35%and the echo signal strength is significantly improved.Finally,C-scan imaging is carried out on the sample to verify the detection ability of EMAT.

Treatment of over 20 mm gastric cancer by endoscopic submucosal dissection using an insulation-tipped diathermic knife

AIM： To evaluate the effectiveness of endoscopic submucosal dissection using an insulation-tipped diathermic knife （IT-ESD） for the treatment of patients with over 20 mm early gastric cancer （EGC）. METHODS： A total of 112 patients with over 10 mm EGC were treated with IT-ESD at Sumitomo Besshi Hospital and Shikoku Cancer Center in the 5 year period from January 2002 to December 2006, including 40 patients with over 20 mm EGC. We compared patient backgrounds, the one-piece resection rate, complete resection （CR） rate, operation time, bleeding rate, perforation rate between patients with over 20 mm EGC [over 20 mm group （21-40 ram）] and the remaining patients （under 20 mm group）. RESULTS： We found no significant difference in the rate of underlying cardiopulmonary disease （over 20 mm group vs under 20 mm group, 5.0% vs 5.6%）, one- piece resection rate （95% vs 96%）, CR rate （85% vs 89%）, operation time （72.3 rain vs 66.5 rain）, bleeding rate （50 vs 4.2%）, and perforation rate （0% vs 1.4%） between the 2 groups. Three patients in each group had submucosal invasion and two in each groups underwent additional surgery. CONCLUSION： There was no significant difference in the outcome resulting from IT-ESD between the 2 groups. Our study proves that IT-ESD is a feasible treatment for patients with over 20 mm mucosal gastric cancer although the long-term outcome should be evaluated in the future.

Improvement of anticorrosion and adhesion to magnesium alloy by phosphate coating formed at room temperature

A new surface protection process was developed to magnesium alloy against corrosion in aggressive environments.Firstly,a phosphate coating was formed on rinsed magnesium alloy.Then,powder painting was carried out on the phosphated magnesium alloy.Surface morphologies and phase compositions of the phosphate coating were investigated by X-ray diffraction(XRD) and scanning electron microscope(SEM) .The results show that the phosphate coatings formed in bath containing earth additives at room temperature have dense and fine microstructure.The phosphate coating provides excellent paint adhesion to the magnesium alloy. Salt spray tests indicate that the corrosion resistance of the phosphate coating plus paint could meet the demand of magnesium alloy automobile components in aggressive environments.

Two-dimensional MOF/MOF derivative arrays on nickel foam as efficient bifunctional coupled oxygen electrodes

Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water electrolysis.However,highly effective and inexpensive earth-abundant materials are sought after to replace the noble metal-based electrocatalysts currently in use.Recently,metal-organic frameworks(MOFs)and carbon-based MOF derivatives have attracted considerable attention as efficient catalysts due to their exceedingly tunable morphologies,structures,compositions,and functionalization.Here,we report two-dimensional(2D)MOF/MOF derivative coupled arrays on nickel foam as binder-free bifunctional ORR/OER catalysts with enhanced electrocatalytic activity and stability.Their remarkable electrochemical properties are primarily attributed to fully exposed active sites and facilitated charge-transfer kinetics.The coupled and hierarchical nanosheet arrays produced via our growth-pyrolysis-regrowth strategy offer promise in the development of highly active electrodes for energy-related electrochemical devices.

Development of the Automated Bonding Robot for Space Solar Cells

The bonding process of space solar cells is a very complicated task undertaken by manual labor before.An automatic approach based on robot technology is presented to deal with the difficult problem.The architecture of the bonding robot for space solar cells is described.The two processes carried out by the robot,adhesive dispensing and cover-glass bonding,are studied.Based on the mechanical model,the flow velocity field of the adhesive in needles is obtained and the cover-glass bonding theory is interpreted.According to the studies,the thickness of the adhesive can be controlled accurately by robot and bubbles can be avoided coming about inside the adhesive.

Degradation of bond between steel bar and freeze-thaw concrete after electrochemical chloride extraction

The effect of electrochemical chloride extraction （ECE） on bond strength between steel bar and freeze-thaw concrete contaminated by chloride was experimentally investigated for beam specimens with dimensions of 100 mm × 100 mm × 400 ram. During the experiment, 3% NaC1 （vs mass of cement, mass fraction） was mixed into concrete to simulate chloride contamination, and the specimens experienced 0, 25, 50, 75 freeze-thaw cycles before ECE. In the process of ECE, different current densities and durations were adopted. It is indicated that the bond strength between reinforcement and concrete decreases with the increase of freeze-thaw cycles; the more the current and the electric quantity of ECE are, the more the loss of bond strength is; and the largest loss is up to 58.7%. So, it is important to choose proper parameters of ECE for the reinforced concrete structures contaminated by chloride and subjected to freeze-thaw cycles.