Concerning the Data of Numerical and Physical Experiments in Studying the Adsorption of Gas and Vapors in Micropores of Active Carbons

Protection of Metals and Physical Chemistry of Surfaces - The conditions for carrying out molecular dynamics calculations of adsorption isotherms of gases and vapors in micropores of active carbons...     

Sorption of vapors and gases by cellulose acetate films

Cellulose diacetate and triacetate films 6–55 µm thick with a total porosity of 0.8–2% were prepared by pouring a solution on an immobile surface and by calendering. Sorption of H₂S and CO₂ gases and acetone vapors on these films was investigated in static and dynamic conditions. It was shown that films 6–10 µm thick prepared by calendering should be used for purification of air from H₂S and CO₂ and films 15–20 µm thick prepared by pouring should be used for removal of acetone vapors.Engels Institute of Technology, Saratov State University. Translated from Khimicheskie Volokna, No. 6, pp. 44–46, November–December, 1995.     

CT of appendicitis in children

PURPOSE: Our goal was to review the CT findings and to help define the role of CT in the evaluation of appendicitis in children. METHOD: Of 730 children with surgically proven appendicitis, 22 underwent preoperative CT evaluation. Their CT scans and operative and pathology records were retrospectively reviewed. The CT scans were evaluated for appendiceal wall thickness, diameter, and location, appendicoliths, pericecal inflammation, phlegmon, abscess, free fluid, small bowel dilatation, and bowel wall thickening. Criteria for diagnosing appendicitis were (a) appendiceal wall thickening (> 1 mm) or (b) presence of abscess, phlegmon, or pericecal inflammation associated with appendicolith(s). Prospective reports of ultrasound examinations performed within 2 days of the CT scans were available in 14 children and were correlated with the CT findings. RESULTS: An abnormally thickened appendix, with a diameter ranging from 9 to 18 mm, was seen in four children. Three appendices were retrocecal and one was near the cecal tip, anterior to the iliac vessels. Appendicoliths were present in 10 children, multiple in 1. Abscesses were seen in 13 of 22 children, multiple in 5. Phlegmon was seen in five children and pericecal inflammation in two. Bowel wall thickening was present in seven children and small bowel dilatation was noted in six. Other findings included free fluid, hydronephrosis, thickening of urinary bladder wall, air in the uterus and vagina, adenopathy, and thickening of the abdominal wall musculature. CT was diagnostic of appendicitis in 11 of 22 children (50%). In 14 children with both ultrasound and CT studies, CT was slightly better in diagnosing appendicitis and visualizing the abnormal appendix and was superior in defining the presence and extent of abscess and inflammation in 9 of 14 children. CONCLUSION: CT is a useful adjunct in diagnosing appendicitis in children, with a major role in cases of complicated appendicitis.     

Congratulations to Vladimir Viktorovich Baulin

Soil Mechanics and Foundation Engineering -     

Quantitative patterns in the clinical manifestations of radiation sickness in large laboratory animals exposed to radiation at superlethal doses. The quantitative patterns in the manifestations of radiation sickness in dogs

Radiation sickness manifestations have been studied in dogs exposed to electrons (electron energy 25 MeV) and gamma-neutron radiation (neutron energies of 0.37 and 1.2 MeV) in a wide dose range. Dose-response relationships have been calculated for mortality and some clinical manifestations of the intestinal and cerebral forms of radiation sickness. With regard to mortality, the highest effect has been observed for gamma-neutron radiation with a neutron energy of 1.2 MeV. For equal physical doses and for those equally effective in relation to mortality, clinical manifestations of damage are more prominent following exposure to electrons.     

Hybridization of acoustic waves in piezoelectric plates

The conditions for hybridization of the zero-order and high-order acoustic waves propagating in a piezoelectric crystal plate have been studied. The dependence of the phase velocity of the hybrid waves on the parameter hf (h is the plate thickness and f is the wave frequency) is established for the potassium niobate and lithium niobate plates possessing various crystallographic orientations and conductivities. It is found that hybridization takes place when the conductivity of a thin surface layer exceeds a certain critical value, which can vary within broad limits depending on the plate material and orientation. The degree of dispersive repulsion of the coupled modes grows with increasing electromechanical coupling coefficient.     

Chelated alkoxyalumoxanes and a silica-free binder based on them

Chelated alkoxyalumoxane oligomers have been synthesized through consecutive hydrolysis and alcoholysis of organoaluminum compounds stabilized by compounds capable of keto-enol tautomerism. The chelated alkoxyalumoxanes were used to prepare a silica-free binder for the fabrication of heat-resistant (up to 2050°C), chemically inert corundum ceramic composites. The likely structures of the synthesized preceramic alumoxane oligomers were inferred from physicochemical characterization results (¹H, ¹³C, and ²⁷Al NMR, IR spectroscopy, mass spectrometry, gel-permeation chromatography, thermal analysis, and elemental analysis).     

Tc(VII) Sorption by Fibrous Sorbents

It is shown that technetium can be extracted from acidic media by the fibrous complexing sorbent POLIORGS 35, containing hydrazidine groups, and from neutral and nitric-acid solutions with a complex salt composition (with nitrate-ion concentration not exceeding 10 g/liter) by strongly basic anionite POLIORGS AV-17 with quaternary ammonium bases. The effect of the pH of the solutions on the sorption of technetium is studied. It is shown that the sorption depends on the nature and concentration of the salt background of the solutions. The kinetics and mechanism of sorption of technetium by fibrous sorbents and the possibility of their desorption and reuse in sorption–desorption cycles are investigated. It is shown that the fibrous sorbents POLIORGS 35 and POLIORGDS AV-17 are promising for extracting technetium from waters with a high mineral content (up to 20 g/liter).