Effect of nickel nitrate on phase changes in mullite and mullite — Corundum refractories when heated in oxidizing and reducing conditions

Conclusions During heating in oxidizing atmospheres of mullite-corundum specimens with an addition of nickel nitrate at 500–900°C, NiO is formed, and an increase in temperature from 900 to 1500°C is characterized by the development of nickel spinel, NiAl₂O₄, the quantity of which increases with an increase in the content of the Ni(NO₃)₂ · 6H₂O, and the firing temperature.The high temperature diffractometric method showed that in the system 3Al₂O₃ · 2SiO₂-NiO heating in oxidizing conditions, and commencing at 1000°C, NiO decomposes the mullite with the formation of aluminonickel spinel, whose quantity rapidly increases with further temperature rise. At 1500°C the mullite is preserved in small quantities.The nickel spinel, formed as a result of heating to 1300°C the mullite-corundum refractory containing 25% Ni(NO₃)₂ · 6H₂O during firing in the silicon carbide mixture and in the hydrogen atmosphere at 1400°C for 30 min, in the main decomposes with the separation of metallic nickel and corundum. However, x-ray patterns confirm that in these conditions the nickel spinel is not completely decomposed.Translated from Ogneupory, No.5, pp.32–36, May, 1972.     

Energy metabolism and fuel mobilization: from the perioperative period to recovery

PURPOSE: Previous studies of monochromatic visual evoked potentials confirm the strong suppression of (the cortical representation of) paracentral retinal areas of functionally amblyopic eyes, by a flat response to a blue stimulus. A clinical trial stimulating these areas with blue light was encouraging, and justified a prospective comparison of this treatment with conventional classic treatment. SUBJECTS AND METHODS: In 50 strabismic children with amblyopia, the blue filter treatment protocol (flash stimulation with, and the wearing of, a blue filter during occlusion of the better eye for one hour daily) was compared with the classical treatment (full time total occlusion by patch) in a prospective matched and randomized study. Patients 3 to 7 years old without previous treatment and a visual acuity up to 0.3 were admitted to the study. Visual acuity and fixation behavior were used as the parameters of comparison. Visual Evoked Potentials by monochromatic flashes were also studied. Results of treatment were compared after 6 months. RESULTS: The visual acuity outcome for the blue filter treatment was "statistically significantly" better (p=0.005). The greatest improvement was seen in the subgroup of children with eccentric fixation (p=0.01). Fixation behavior also showed a better outcome from the blue filter treatment (p=0.05) favoring especially children between 3 and 5 years. In children of this age with a visual acuity better than 0.1 we found a very "statistically significant" difference between the two treatments (p=0.004). In children 3 to 5 years old with poorer visual acuity we also found a "statistically significant" difference in the two treatments (p=0.04). The interocular difference of amplitude on the Visual Evoked Potentials also demonstrated more improvement in children treated with the blue filter. This treatment improved especially the cortical response to blue flash stimulation, correlating to paracentral retinal areas. CONCLUSIONS: The blue filter treatment protocol provided better results for treating amblyopia than the conventional classic occlusion treatment method. We propose that stimulation of these paracentral retinal areas triggers a better disinhibition of a functionally amblyopic eye.     

Synthesis of the nitrogen-fixing enzyme system in oligonitrophilic bacteria

Oligonitrophilic bacteria were cultivated on a medium containing only 2.5--10.0 mg/litre of nitrogen compounds. They assimilated elementary nitrogen only after utilization of these nitrogen compounds during growth and formation of nitrogen-fixing enzyme system. Their cells grown on a medium containing high concentrations of bound nitrogen did not fix nitrogen during further incubation in the atmosphere of 15N; therefore, the enzymes involved in nitrogen fixation were induced. These organisms are characterized by diauxia during their growth on media containing "start" doses of nitrogen. Enzymes catalysing nitrogen fixation in azotobacter are also induced. But, contrary to oligonitrophilic bacteria, the azotobacter does not require nitrogen compounds in the medium in order to adapt to molecular nitrogen, and its growth curve is not of a biphasal character. These data and the evidence of other authors suggest that all nitrogen-fixing microorganisms are characterized by the induced, not constitutive, enzymes involved in reduction of molecular nitrogen.     

Some problems of the moral and psychological training of medical service personnel

The authors' experience with 45 papillosphincterotomies, performed for diseases of bile passages and chronic pancreatitis, is reported. The details of the operative technic, employed by the authors, are described. The technic of papillosphincterotomy on a conus-shape sound by means of a "laser scalpel" proved to be the most perfect one. Careful observation of the surgical technic made it possible to gain favourable results--only 1 of 45 operated patients died. Papillosphincterotomy is largely advocated in stenoses and concretions in the large duodenal papilla, strictures of choledocho-duodenoanastomoses, care should be taken not to overwiden indications to the operation concerned.     

Anti-macrophage monoclonal antibody D-11 in the diagnosis of histiocytic tumors

Anti-macrophage monoclonal antibody (Mab) D-11 was tested in surgical material and biopsies of non-epithelial tumors and tumor-like lesions from 181 patients in order to assess possibility of using this Mab for diagnosis of histiocytic tumors, malignant fibrous histiocytoma in particular. The study was performed in parallel on cryostat sections and smears by immuno-peroxidase method. It is established that D-11 reacts positively with both histiocytic tumors and tumors of other genesis this being a limiting factor in differential diagnosis of histiocytic tumors. However, taking into consideration 100% of positive results with histiocytic tumors only, this antibody can be used for exclusion of tumors studied from the group of histiocytomas in cases of negative reaction.     

The x-ray morphometric characteristics of the spine in persons 50 and older

To specify shape of the vertebra in relation to age and sex, the authors studied roentgenomorphometric evidence upon examination of the thoracic and lumbar spine in 600 patients over 50. Vertebral deformities were found in 45.1 and 44.5% of the examined males and females, respectively. Changes corresponding to vertebral body fracture were recorded in 12.3% of the males and 15.3% of the females. Age-related trends in the frequency of various defects have been analyzed. The frequency differed in males and females.     

Phase formation in the ZrO2 — HfO2 — Gd2O3 and ZrO2 — HfO2 — Yb2O3 systems

The formation of phases and properties of solid solutions and Gd₂Zr₂O₇ and Yb₄Zr₃O₁₂ chemical compounds in the ZrO₂ — Gd₂O₃ and ZrO₂ — Yb₂O₃ systems are studied. The compounds undergo a phase transformation of the type“order — disorder” and melt incongruently. The data on the parameters of the elementary cells, the melting temperatures, and the TCLE of phases in the ZrO₂ — Gd₂O₃ and ZrO₂ — Yb₂O₃ systems are presented. These data are compared with similar data for phases based on HfO₂. The considered solid solutions are shown to be promising for the production of high-temperature, heat-insulating ceramics for growing single crystals.     

The concepts of quantum theory can be introduced into psychophysiology

Changes in the structural proteins and hydration during aging is responsible for altered skin morphologic and mechanical properties manifested as wrinkling, sagging, loss of elasticity, or apparent dryness. To gain insight into the age-related alterations in protein conformation and water structure, we obtained Raman spectra from the sun-protected buttock skin representing chronologic aging and the sun-exposed forearm skin representing combined effects of photoaging and chronologic aging. Ten aged individuals (five men, five women; age range 74-87) and 10 control young individuals (five men, five women; age range 22-29) entered the study. In the photoaged forearm skin the positions of protein-specific amide I, amide III, and CH stretching bands were shifted, suggesting increased protein folding. In contrast, major changes were seen only in the amide I peak in chronologically aged skin. The intensity of the 3250 cm(-1) OH stretching band was increased in photoaged skin (but not in chronologically aged skin) indicating an increased water content. R(v) representation of the low-frequency region of Raman spectra was applied to determine water structure. In the young skin and chronologically aged skin water was mostly present in the bound form. In the photoaged skin, however, an increase in intensity at 180 cm(-1) was noted, which reflects an increase in the not-protein bound water (tetrahedron water clusters). In conclusion, it seems that proteins in the photoaged skin are more compact and interact with water to limited degree. Impairment in protein hydration may add to the understanding of ultrastructural, mechanical, and biochemical changes in structural proteins in the aged skin.