Negative wake behind bubbles in non-newtonian liquids

GAS bubbles rising by gravity in non-newtonian elastic liquids(1-4) are different to gas bubbles in viscous newtonian fluids in at least two ways. First, the bubbles in the non-newtonian liquids often have a peculiar tip at the rear pole, and second, the terminal rise velocity versus volume curve often has a discontinuity at a certain 'critical' volume. To investigate this unusual flow situation further we have used laser-Doppler anemometry(5) to measure the liquid velocity in the wake behind air bubbles in a non-newtonian liquid. The measurements described here reveal the unexpected result that the liquid velocity behind the bubbles is in the downwards direction away from the rising bubbles (the velocities are referred to an observer at rest with respect to the liquid far from the bubbles). Thus the liquid velocity is opposite to the velocity in the usual wake behind objects moving in viscous newtonian fluids and we have called the phenomenon 'negative wake'.     

Modulation of antibody synthesis by an anti-tumour alga

Summary An unicellular alga,Chlorella pyrenoidosa, which had been reported to protect C₃H mice against sarcoma BP8, is shown, when injected in Freund's incomplete adjuvant, to modulate the antibody synthesis induced by immunization with a hapten-carrier complex.C. pyrenoidosa appeared to be able to initiate an antigenic competition between hapten and carrier determinants of the antigen molecule during antibody synthesis, and thus it could be speculated thatC. pyrenoidosa modulates the immune response at the macrophage level.Acknowledgments. This work was supported by the Secrétariat d'Etat aux Universités and by the DGRST, grant No. 77.71347.     

Electron microscopic observation of nucleosomes in ultrathin sections of heparin-treated nuclei

Summary Isolated rat liver nuclei display nucleosomes (-bodies) in common ultrathin sections after treatment of nuclei with heparin. The masking of nucleosomes in intact chromatin by some extranucleosomal component is suggested.     

In situ noradrenaline-induced stimulation of dog thyrotrophic secretion

Summary Anterior pituitary microinfusions of noradrenaline in the dog causes a significant release of TSH while adrenaline and dopamine do not.This study was supported by Grant No. S1-049 from the Consejo Nacional de Investigaciones Cientificas y Tecnológicas, Grant No. 281 from the Consejo de Desorrallo Cientifico y Humanístico, Central University of Venezuela, and Fundación José María Vargas.     

Effects of carmine and carminic acid on embryonic tissue cell cultures

Summary The biological reaction to carmine and carminic acid at cellular level on in vitro cultures was tested and significant variables were controlled. Results suggested that proliferation and metabolism of these cultures were not affected by the 2 stains.     

The secret of truffles: A steroidal pheromone?

Summary The steroid 5-androst-16-en-3-ol has a pronounced musk-like scent. It is a major constituent of the pheromone of the boar. It occurs also in axillary sweat of men but is devoid of androgenic activity. The presence of this steroid has been demonstrated in truffles (Tuber melanosporum) both by radioimmunoassay and by gas chromatography-mass spectrometry in quantities of 40–60 ng/g fresh material. This offers an explanation for the ability of pigs to detect truffles growing as deep as 1 m under ground.     

Prevention of estrogenic inhibition of adrenal 686-1686-1686-1686-2686-2686-2in rats

Summary The urinary protein _2u stimulates adrenal ⁵-3 dehydrogenase activity and prevents adrenal enlargement in estrogen-treated adult male rats.Acknowledgements. Dehydroepiandrosterone used in this study was donated by Organon(India) Ltd, Calcutta. This work received financial support from University Grants' Commission, New Delhi. The author's thanks are due to Prof. A. K. Maiti and Prof. C. Deb, Department of Physiology, Calcutta University, for their constant encouragement.     

空间低频滤波对人类整体和局部知觉的影响

利用功能磁共振(fMRI)测量血液动力学反应, 研究空间低频滤波对周边视觉加工刺激整体和局部性质的神经机制的影响. 实验中使用的复合字母具有宽带空间频率成分(宽带刺激)或通过反差平衡技术滤除其空间低频成分(CB刺激), 随机呈现在左或右视野. 被试分别辨别复合字母的整体和局部形状. 实验发现, 与注意局部性质相比, 注意宽带或CB刺激的整体性质在中央枕区皮层引起更强的激活. 注意整体性质还在右侧颞顶联合区(宽带刺激)和右侧梭状回(CB刺激)引起更强的激活. 注意CB刺激的局部性质激活中央额区、双侧额下回和双侧颞上回. 根据这些结果讨论了整体和局部性质加工的相互竞争对参与整体和局部加工的脑区的影响.     

Study on the Ground Surface Quality of Cr_2O_3 Coatings

The ground surface quality of Cr 2O 3 coatings is investigated in this paper. The influence of some typical grinding parameters on ground surface integrity is discussed in detail. It is found that the ground surface roughness increases with the increase of depth-of-cut. The surface finish is improved as the increase of grinding speed, but too high grinding speed may result in serious vibration of the system. The increase of workpiece speed causes deterioration of surface finish and produces big grinding n...     

Synthesis and characterization of copper foams through a powder metallurgy route using a compressible and lubricant space-holder material

In the present work, a compressible and lubricating space-holder material commonly known as “acrawax” was used to process Cu foams with various pore sizes and various porosities. The foams were processed without using binders to avoid contamination of their metal matrices. The lubricant space-holder material was found to facilitate more uniform flow and distribution of metal powder around the surface of the space holder. In addition, the use of acrawax as a space-holder material yielded considerably dense cell walls, which are an essential prerequisite for better material properties. The foams processed with a smaller-sized space holder were found to exhibit better electrical and mechanical properties than those processed with a coarser-sized space holder. The isotropic pore shape, uniform pore distribution throughout the metal matrix, and uniform cell wall thickness were found to enhance the properties pertaining to fine-pore foam samples. The processed foams exhibit properties similar to those of the foams processed through the lost-carbonate sintering process.