Modification of the shape of large germanium nanoislands on silicon surface by low-energy ion bombardment

Germanium nanoislands on silicon substrates were irradiated by hydrogen and argon ions with energies below 350 eV. In the initial stage, ion bombardment leads to the division of large islands into several small islands irrespective of the ion type. The resulting surface is more homogeneous than the initial and is stable with respect to further ion irradiation.     

Mutagenic activity detected by the Ames test in river water under the influence of petrochemical industries

The present study was carried out on the waters of the Caí River (Rio Grande do Sul, Brazil) in an area under the influence of a petrochemical industrial complex, as the continuation of a study in which the mutagenic activity of water samples was evaluated in the internal area of this complex. In the previous study, the release of inducing substances was detected, revealing the need for a full analysis of the real ecological impact of the industrial complex on the river. Water samples from different sites along the Caí River were subjected to the Ames test during a study of 20 months duration for the detection of possible mutagens. Strains TA100 and TA98 were used for initial sample screening in the presence and absence of the S9 mix at a standard dose of 2000 microliters/plate. When positive activity (values equal to twice the spontaneous mutation rate) and/or cytotoxic activity (cell survival below 60%) was detected, the dose-response relationship was studied. Thirty-four percent of the samples tested were mutagenic, with different values according to collection site. Of the total number of positive responses, 6% were obtained for samples collected at the blank site upstream from the area studied, 82% at sites closest to the industrial complex, and 12% in downstream areas. Strain TA98 was the most sensitive in assays with no metabolic activation. A low frequency of induction (2%) was observed for strain TA102. Application of the Ames test permitted the delimitation of three areas of influence of the petrochemical industrial complex, and the test proved to be adequate for the detection of contaminants from the petrochemical industry.     

Effect of a strong magnetostatic field on proliferation of duodenal epithelial cells in mice

The proliferative activity of duodenal epithelial cells in mice subjected to the effect of a 1000-Oe magnetostatic field (MSF) was studied. It was established that the one-day effect of a strong MSF causes transient disturbance of cell division processes. This is indicated by changes in the mitotic index and content of cells in the duodenal crypt, and also by the increase in the number of pathological forms of mitoses with a predominance of chromosomal damages.     

Method of “joining” of solutions in the determination of a plane and a cylindrical phase interface in the Stefan problem

It is shown that the position of the phase interface in the Stefan problem can be expressed through two functions: One function determines the position of the melting-temperature isotherm in the problem without phase transitions and the second does not depend on time.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 33, No. 1, pp. 148–152, July, 1977.     

On the metabolic characteristic of hybrids Shigella flexneri x Escherichia coli devoid of their ability for intracellular multiplication in the epithelial cells. I. Glycolysis

In order to evaluate the effects of ultrasonic nebulization on airway resistance in respiratory failure, ten patients requiring mechanical ventilation for acute pulmonary failure were each ventilated with two humidification systems, one producing inspired air saturated with vapour at 35 degrees C, the other nebulizing water droplets ultrasonically. There was no statistically significant difference in pulmonary resistance at inspiratory flow rates of 40, 60, AND 80 1/min. A separate comparison between humidifiers in those patients with the highest resistances did not reveal any difference in response to method of humidification. In contrast to studies in other contexts, these data fail to show any significant difference, from the standpoint of effects on resistance, in the use of ultrasonic mist humidification during mechanical ventilation for respiratory failure.     

Carbohydrate tolerance in the puerperium during suppression of lactation with bromocriptine and oestrogens

The influence of bromocriptine on carbohydrate tolerance in the puerperium was examined and its effects compared with those of an oestrogenic compound. Sixteen patients were studied in each group. The controls consisted of 16 women who were breast-feeding. Compared with the controls, no significant difference was found in the oral glucose tolerance test in patients who had oestrogen, but blood glucose values in women receiving bromocriptine were significantly lower. Inhibition of lactation with bromocriptine may obscure abnormal glucose tolerance.