Void formation in an Al-Mg-Si alloy under different precipitation conditions after irradiation with 100 keV Al ions

The influence of different precipitation treatments upon the radiation-induced void formation was studied on an Al-Mg-Si alloy and the results were compared with those obtained on high-purity Al. The changes in the microstructure and the void formation were investigated by TEM methods for the dose range 0.8 to 80 dpa and the temperature range 55 to 250° C. The irradiations were carried out using 100 keV Al ions. Highpurity Al showed void formation over the whole temperature range investigated with a maximum volume increase V/V of 3.4% at 150° C. The behaviour of the Al-Mg-Si alloys depends strongly upon the thermal pretreatments. The alloy in its homogenized state shows no voids between 55 and 140° C. Trapping of vacancies on solute Si atoms could be the explanation. An ageing treatment leading to coherent precipitates results in the complete suppression of void formation for the temperature region of highest swelling (0.35 T _sT0.44 T _s). On the other hand, treatments which cause incoherent or partially coherent precipitates result in swelling. The amount of swelling, however, is lower compared to pure Al and the temperature of the swell maximum is shifted to lower temperatures. These results could be explained by the mechanism of trapping vacancies by solute atoms, on the one hand, and the coherent precipitates acting as recombination centres, on the other.     

Kinetics of reduction of nickel chloride with hydrogen

The kinetics of reduction of nickel chloride with hydrogen were investigated in the temperature range of 533 (260 °) to 788 K (515 °). Most experiments were done with porous NiCl2 granules having ?8+10 mesh (Tyler) size. The effects of temperature, sample size, granule size and hydrogen partial pressure on the reduction kinetics were investigated. In the temperature range 533 (260 °) to 651 K (378 °) the reduction is dominated by chemical kinetic factors. At higher temperatures diffusional effects appear to become quite significant. The temperature-dependence of the chemical kinetic rate constantK is given by $$\log K = 6.744 - \frac{{22,240}}{{2.303RT}};K\,\,is\,\,in\,\,\min ^{ - 1} $$ The activation energy for the reduction was found to be 22,240 cal /mol (or 93,050 J/mol) in the chemical kinetic regime.     

Thermopower ofAg_{2 + \delta } S across theα-β transitionacross theα-β transition

Thermopower data of S in both of itsα- andβ-phases are reported and the results are compared with the data on Se. Communication No. 129 from the Solid State and Structural Chemistry Unit.     

Some notes on cellular logic operators

Cellular logic machines used for feature extraction in pattern recognition have increased in speed to the point of making it possible to execute programs equivalent to 1 billion general-purpose computer instructions in 1 TV frame time. Unfortunately, most cellular logic operators (CLO's) are designed ad hoc. It is important, therefore, to begin to systematize the generation of algorithms using CLO sequences for pattern analysis. These notes systematically analyze some aspects of CLO's which are used in shape discrimination and idealization and in object counting and sizing. New extensions of subfield numbering schemes in the hexagonal tessellation are introduced.     

Improved Synthesis and Physicochemical Properties of Alkoxylated Inulin

Inulin, a polydisperse reserve polysaccharide extracted from chicory, has been modified by alkoxylation in a water-free medium using a basic catalyst. The reaction of inulin with ethylene oxide, as well as propylene oxide, was performed in an organic solvent, N-methylpyrrolidinone, with triethylamine as basic catalyst in almost quantitative yields. The reaction resulted in a range of products with very specific properties such as highly increased water solubility, moderate surface activities and very high cloud points in electrolyte media.     

Localization of vitamin A in the small intestine of mouse. An electron microscope radioautographic study

Localization of vitamin A in the small intestine of mice was studied with electron microscope radioautography after administration of tritiated vitamin A. The label was concentrated over lipid droplets in cells distributed in the lamina propria and the submucous layer. The cells were similar both to fibroblasts and to fat-storing cells in their morphological features. The name "Vitamin A-Storing Cell" is proposed for these labeled cells, including the fat-storing cell in the liver.     

Detection of edges using range information

Range data provide an important source of 3-D shape information. This information can be used to extract jump boundaries which correspond to occluding boundaries of objects in a scene and ``edges' which correspond to points lying between significantly different regions on the surface of objects. We are mainly interested in range data obtained from sensors such as lasers. The main problem with this type of range finder is the fact that the accuracy of the measurements depends on the power of the signal that reaches the receiver. This study describes how a range edge detection procedure can be designed that has low sensitivity to noise and imbeds all the knowledge available on the range measurement accuracy.