高硬质NR/BR并用胶的增硬补强体系研究

研究了苯甲酸、酚醛树脂和高苯乙烯/C8树脂三类增硬补强剂对高硬质NR/BR并用胶的增硬补强效果。实验结果表明:苯甲酸增硬效果明显,尤其用量在3.0份时,胶料硬度大幅度提高,但是对其它力学性能有一定的损害;酚醛树脂的增硬效果最好,特别适合于制作邵A硬度95以上的超高硬度制品;高苯乙烯/C8树脂的增硬程度相对较小,但是所获得胶料的综合物理性能最好。

一液型鞋用高硬质干法面层聚氨酯树脂合成研究

介绍了当前合成革市场中鞋用高硬质人造革表皮层干法树脂的合成,分析了树脂在合成中聚酯多元醇、链伸长剂、异氰酸酯、溶剂各物质比例,以及对耐屈折性、抗张力、挥发性和耐热性等产品性能的影响。

Research and Development of Cemented Carbide Multifacet Drill for Drilling High Strength Steel

Aim To research on a solid cemented carbide multi facet drill for drilling high strength steel. Methods Assimilating some features of multi facet drill edge structures, through systematic drilling experiments, a new type of solid cemented carbide drill was developed and the drill geometry was optimized. Results With the new type drill,the drilling force decreases by 10%-20%, the drilling productivity (drilled holes per hour) increases by 2-3 times, and the drilling precision and surface finish increase by one level. Conclusion The new type drill possesses excellent drilling performance.

CUTTING FORCES IN HIGH SPEED TAPPING CAST IRON BY TUNGSTEN CARBIDE TAPS

The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent.

CUTTING FORCES FOR HIGH-SPEED DRILLING OF COMPOSITES

The thrust and the torque of various carbide drills are studied for the high-speed drilling of fiber reinforced epoxy composites. The orthogonal experiment is carried out with different feed speeds at high rotation speed. Experimental results show that the spindle rotation speed is the most influential factor. The thrust andthe torque decrease under the condition of high rotation rate. With the decrease of the feed speed, the thrust and the torque decrease. But the effect of the feed speed is less than that of the spindle rotation rate. Moreover, the effect of drill materials on the thrust and the torque is more notable than that of the drill geometries and the feed speed. The thrust is greatly affected by the feed speed while the torque is obviously affected by drill geometries.

人类疾病80%与饮用水有关

世界卫生组织调查指出，人类疾病80%与水有关。据统计，每年世界上有2500万名以上的儿童因饮用被污染的水而死亡。有关资料显示，我国有24%的人饮用不良水质的水，约1000万人饮用高氟水，约3000万人饮用高硬质水，5000万人饮用高氟化物水，而这些数据每年均呈上升趋势。

Attenuation of portal hypertension by natural taurine in rats with liver cirrhosis

AIM： To investigate the inhibitory effect of natural taurine （NTau） on portal hypertension （PHT） in rats with experimentally-induced liver cirrhosis （LC）. METHODS： Experimentally-induced LC Wistar rats （20 rats/group） were treated with either oral saline or oral NTau for 6 consecutive weeks. Evaluation parameters included portal venous pressure （PVP）, portal venous resistance （PVR）, portal venous flow （PVF）, splanchnic vascular resistance （SVR） and mean arterial pressure （NAP）. Vasoactive substance levels including nitric oxide （NO）, nitric oxide synthase （NOS） and cyclic guanosine monophosphate （cGMP） were also measured. Histological investigation of type Ⅰ and Ⅲ collagen （COL Ⅰ and Ⅲ） and transforming growth factor-β1 （TGF-β1） was also performed. RESULTS： Treatment with NTau （1） significantly decreased PVP, PVR and PVF, and increased MAP and SVP; （2） markedly increased the vascular compliance and reduced the zero-stress of the portal vein; （3） markedly decreased the amount of NO and cGMP and activity of NOS; and （4） improved the pathological status of the liver tissue and reduced the expression of COL Ⅰ, COL Ⅲ and TGF-β1. CONCLUSION： NTau inhibited the LC-induced PHT by improving hyperdynamic circulation, morphology of liver and biomechanical properties of the portal vein in experimentally-induced LC rats.

Characterization of shear stresses in nickel-based superalloy Mar-M247 when orthogonal machining with coated carbide tools

Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytical force model to indicate the effect of coating material, cutting speed, feed rate on tool life and surface roughness was conducted experimentally. Cutting tests were performed using round inserts, with cutting speeds ranging from 50 to 300 rn/min, and feed rates from 0.1 to 0.4 mm/tooth, without using cooling liquids. The behavior of the TiN and TiCN layers using various cutting conditions was analyzed with orthogonal machining force model. Cutting results indicate that different coated tools, together with cutting variables, play a significant role in determining the machinability when milling Mar-M247.

Experimental constraints on the genesis of Jadeite quartzite from Shuanghe,Dabie Mountain ultra-high pressure metamorphic terrane

Jadeite quartzite, essentially a two-phase rock made up of jadeite and quartz, is one of the most important UHP lithologies occur- ring in the Dabie Mountain ultrahigh pressure metamorphic belt and forms layers in biotite-plagioclase gneiss. High pressure- high temperature studies on natural albite from the country rock gneiss were undertaken to reveal the--in parts----complex mineralogical changes that occur in the jadeite quartzite during prograde metamorphism. Experiments were conducted at 800- 1200~C, in the pressure range of 2.0-3.5 GPa. One of the most intriguing results shows that the low pressure boundary of the jadeite＋coesite stability field is located between about 3.2 GPa at 1000~C and 3.4 GPa at 1200~C, thus about （0.2-0.3）_＋0.1 GPa higher than the quartz-coesite transition curve, given the uncertainty in the present study. Minor amounts of sodium and aluminum entering the structure of quartz and the intimate intergrowth texture of the run products may contribute to the ob- served pressure shift. Combined petrological and mineralogical studies on the run products and the natural rocks yield the fol- lowing prograde reaction sequence to have occurred： The protolith of the jadeite- quartzite from Dabie Mountain is an albitized siltstone/greywacke characterized by an albite＋quartz assemblage. During prograde metamorphism albite breaks down to form jadeite＋quartz and thus at this stage two types of quartz can be distinguished whereas type-I-quartz already existed in the pro- tolith, type-II-quartz represents a newly formed reaction product of albite. During further P-T-increase the pure type- I-quartz was transformed to coesite, whereas type-II-quartz （together with jadeite） was still present as a stable phase because of its im- purities of Na and A1. At a later stage during further subduction, type-II-quartz also decomposes to form coesite. These studies represent an important puzzlement for a better understanding of the evolution of jadeite- quartzite from the Dabie Mountain during continental crust subduction and thus contribute to a more complete knowledge of the formation of the Dabie Mountain UHP orogenic belt in general.