Liquid paraffin

About: Liquid paraffin is a research topic. Over the lifetime, 6185 publications have been published within this topic receiving 52956 citations.

Toughened hard alloy and preparation method thereof

Abstract: The invention discloses a high-toughness toughened hard alloy which comprises 10%-30% of Co or Co and Ni serving as a binding phase, 0-1.5% of Cr3C2 serving as an inhibitor, and the balance of hard phase WC, wherein the hard phase consists of WC crystalline grains with coarse, medium and fine grain sizes, the grain size of coarse grains is 9-15 mu m, the grain size of medium grains is 4-7 mu m, the grain size of the fine grains is less than 2 mu m, and the mean grain size of the hard phase WC is 1.6-3.2 mu m. The preparation method of the toughened hard alloy comprises the following steps of: preparing materials including 10%-30% of cobalt powder or cobalt powder and nickel powder, 0-1.5% of chromium carbide powder, and the balance of tungsten carbide powder, wherein Fsss grain size of the coarse grains WC is 9.0-11.0 mu m, the coarse grains WC account for 20%-42% of the prepared powder, the Fsss grain size of the medium grains WC is 4.0-6.0 mu m, the medium grains account for 10%-25% of the prepared powder, the Fsss grain size of the fine grains WC is 1.0-2.0 mu m, and the fine grains account for 20%-40% of the prepared powder; grinding, wherein a liquid paraffin forming agent which accounts for 2% of the prepared materials is added, mixed with absolute ethyl alcohol in a liquid-solid ratio of 300 ml/kg-350ml/kg, wet-ground for 20-28 hours according to the condition that the ratio of grinding media to material is 4:1, and sprayed and dried to obtain mixed materials; pressing; vacuum-sintering and isostatic-pressing and sintering. According to the invention, the toughness is improved on the premise of ensuring the hardness of the alloy, so that the operation field is expanded, special requirements of a cold-heating and cold-punching mould and a holt-rolling hard alloy roller ring are satisfied, and the service life of the high-toughness toughened hard alloy is prolonged.

S-Allylcysteine, a Garlic Constituent, Inhibits 7,12-Dimethylbenz[a]Anthracene-Induced Hamster Buccal Pouch Carcinogenesis

Abstract: The effect of S-allylcysteine (SAC), a water-soluble garlic constituent, on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis was investigated in male Syrian hamstes. Forty hamsters were divided into 4 groups of 10 animals. The right buccal pouches of the animals in Group I were painted with a 0.5% solution of DMBA in liquid paraffin three times a week. The animals in Group II were painted with DMBA as in Group I and, in addition, received 200 mg/kg body wt p.o. SAC three times a week on days alternate to DMBA application. Group III animals received SAC as in Group II. Group IV animals received neither DMBA nor SAC and served as the control. The hamsters were killed after an experimental period of 14 wk. Measurement of lipid peroxidation, the antioxidant enzymes superoxide dismutase (SOD) and catalase, in the buccal pouch mucosa, liver, and circulation was used to monitor the chemopreventive potential of SAC. All hamsters painted with DMBA alone developed tumors identified histologically as well-differentiated squamous cell carcinomas. In hamsters bearing DMBA-induced buccal pouch tumors, diminished lipid peroxidation in the tumor tissue was accompanied by decreased activities of SOD and catalase, whereas in the liver and circulation, enhanced lipid peroxidation was associated with compromised antioxidant defenses. Administration of SAC suppressed the incidence of DMBA-induced HBP tumors as revealed by the absence of carcinomas. Histologically, only keratosis was observed. SAC modulated DMBA-induced decreased susceptibility of the HBP to lipid peroxidation while simultaneously enhancing SOD and catalase activities, whereas in the liver and circulation, SAC decreased the extent of lipid peroxidation and significantly enhanced antioxidant activities. We suggest that SAC exerts its chemopreventive effects by modulating lipid peroxidation and enhancing antioxidant activities in the target organ as well as in the liver and circulation.

The voluminal changes of swim bladder of larval red sea bream Pagrus major

Abstract: Rearing experiments were made to determine the mechanism of diel swim bladder inflation and deflation in the red sea bream Pagrus major larvae. Swim bladder volume index (V/L3•10-6) was found to increase remarkably with growth during the larval stage, and remain nearly constant in the juvenile stage.The volume index was higher at night than in the day time under natural light conditions. However, under constant 24-h illumination such differences could not be observed. By changing the light conditions from dazk to light, the volume index decreased to half within 2h. Furthermore, with the reverse changing from light to dark, it increased to maximum level about lh after the onset of dark. Sealing the water surface of the tank with a layer of liquid paraffin, did not interfere with swim bladder inflation under dark condition and larvae clearly displayed the diel rhythm of night-inflation and day-deflation under natural light conditions.These results suggest that increase in the swim bladder volume in the physoclist species of red sea bream, is not caused by swallowing air at the water surface such as takes place in the physostome species of anchovy, but by the internal gaseous exchange mechanism of the swim bladder according to environmental light conditions.