Showing papers by "Sofia University published in 1968"

Systemic lupus erythematosus and neoplasia of the lymphoreticular system

Abstract: SUMMARY. Two patients are reported with clinically and immunologically typical systemic lupus erythematosus (SLE). Both subsequently developed neoplastic disorders of the lymphoreticular system—lymphatic leukaemia and Hodgkin's disease. In both patients the LE phenomenon and antinuclear antibody tests were initially positive but became negative as the lymphoma developed. Forty control patients with lymphomas, metastasizing carcinoma or sarcoidosis were submitted to similar immunological investigations. The LE phenomenon was positive in only 2. The possible relationship between SLE and lymphomas and other so-called immunoproliferative disorders is discussed. The relatively frequent occurrence of immunological abnormalities in the reticu-loses iand the occasional instances of an apparent transition from SLE to a reticu-losis lend some support to such an hypothesis, but there may be other explanations for these phenomena. We wish merely to record our findings and to emphasize the importance of intensive investigation of the possible relationship between SLE and immunoproliferative disorders.

Possibility of Investigating Movement in a Group of Ants by the Mössbauer Effect

Abstract: THE probability of recoil-free resonance absorption of gamma-quanta depends on the relative velocities of source and absorber1,2. The velocity distribution of moving absorbers can be deduced from the form of the resonance line. In principle this is possible when the velocities are within the range of the Mossbauer spectrometer. In practice they should have a resonance width close to that of stationary absorbers because otherwise their line can become so broad as to cause considerable difficulty3.

Habit types and genesis of phenakite and willemite

Abstract: The crystal habits of phenakite and willemite vary from shortened along the c-axis to prismatic and acicular in good agreement with the chain-like arrays of atoms and factors like temperature, rate of crystallization and supersaturation. A decrease of Si/Be and Zn/Mn ratios seems to favour shortening of the habit. Twinning in phenakite crystals becomes more frequent with higher supersaturations, whereas lack of twinning and frequent {0001} faces in willemite are explained in terms of size of the constituent atoms (Zn and Mn) and stressed covalent bonds. Der Kristall-Habitus von Phenakit und Willemit schwankt zwischen kurzsaulig nach der c-Achse bis prismatisch und nadelformig in guter Ubereinstimmung mit der kettenformigen Anordnung der Atome und den Faktoren wie Temperatur, Kristallisationsgeschwindigkeit und Ubersattigung. Eine Abnahme des Verhaltnisses Si/Be bzw. Zn/Mn scheint die Verkurzung des Habitus zu begunstigen. Die Zwillingsbildung bei Phenakit-Kristallen wird haufiger mit hoheren Ubersattigungen, wahrend das Fehlen der Zwillinge und das haufige Auftreten der {0001}-Flachen beim Willemit mit der Grose der am Aufbau beteiligten Atome (Zn und Mn) und der starkeren kovalenten Bindung erklart wird.

Catalytic determination of microamounts of zinc

Abstract: A catalytic method for determination of micro amounts of zinc has been developed, based on its catalytic action on the decarboxylation of oxalacetic acid. The high sensitivity of the reaction is due to the increase in the effective charge on the metal ion catalyst, when dioxan-water is used as a reaction medium. The determination of more than 5μg of zinc is possible with sufficient accuracy. The method has been applied to the determination of zinc in plants.

Catalytic determination of ultramicro amounts of silver in high-purity zinc and cadmium

Abstract: The oxidation of hydrochloric acid with cerium(IV), catalysed by traces of silver(I), was investigated. The influence of temperature, acidity, reagent concentration and ionic strength on the reaction kinetics was studied. On the basis of these investigations a catalytic method has been worked out for determination of ultramicro amounts of silver. The method permits the determination of silver down to 6 ·10−6% in high-purity cadmium and zinc without preliminary separation. The relative error (95% confidence limits) is ± 13%. The total time needed for the determination is about an hour.

Diagnosis and treatment of malignant melanoma in bulgaria

Abstract: SUMMARY. The available diagnostic procedures for malignant melanoma are critically discussed. The hazards of simple excision biopsy can be reduced by the technique of radiation or chemotherapeutic cover. Methods of treatment are reviewed and the 5 year follow-up results of the treatment of 136 patients in the author's clinic are reported. It is concluded that both radiation and surgery have a place in the treatment of this tumour.

Crystal morphology of fayalite from copper converter slags

Abstract: Fayalite crystals occurring in experimentally obtained copper converter slags with variable SiO2 contents are described. The crystals differ in the degree of skeletal growth which is explained in terms of hindrances in heat transfer brought about by the increasing viscosity of the melt upon increase of the SiO2 content. The formation of tubular inclusions in crystals elongated along the b-axis is related with the influence of sulphide droplets at the surface of the crystals. In der vorliegenden Arbeit werden Fayalitkristalle von experimentell hergestellten Kupfer-Konverterschlacken beschrieben. Die Kristalle unterscheiden sich nach dem Grad des Skelettaufbaues. Diese Tatsache wird durch Hemmungen des Warmetransports erklart, die ihrerseits mit der zunehmenden Viskositat der Schmelze beim Anwachsen des SiO2-Gehaltes verbunden sind. Die Entstehung von rohrenformigen Einschlussen in nach der b-Achse gestreckten Kristallen wird durch den Einflus von Sulfid-Tropfen auf der Oberflache der Kristalle gedeutet.

Complex activators in analytical catalytic reactions

Abstract: The influence of pairs of carboxylic acids on the oxidation ofp-phenetidine hydrochloride by chlorate and traces of vanadium(V) as catalyst is studied. The activator systems used are sulphosalicylic acid + tartaric acid, sulphosalicylic acid + citric acid, tartaric acid + citric acid. It is shown that in some cases the joint activating effect is much higher than that of either activator alone. The kinetic data obtained with complex activator systems confirm the concept of different types of activating action in the two stages of the catalytic reaction. Some combinations of activators could be used in catalytic analysis.

Accelerating effect of hydroxycarboxylic acids in the oxidation of vanadyl(IV) by potassium chlorate

Abstract: The influence of citric, tartaric, sulphosalicylic and oxalic acids on the oxidation of vanadyl(IV) by chlorate is studied. The investigation is carried out in order to clarify the influence of the carboxylic acids on each stage of the homogeneous catalytic processes with vanadium(V) as catalyst. It is found that the oxidation of VO2+ is accelerated in the presence of some carboxylic acids, by a matrix mechanism. If the reaction conditions favour the formation of co-ordinatively saturated complexes, the reaction rate decreases. This is observed also when the carboxylic acid does not possess bridging groups and cannot act as a matrix.

Certain peculiarities of axial electron flow with excess energy of the Penning structure

Abstract: An experimental study was made of the outgoing flow of axial electrons with excess energies from the Penning structure with Al and -Mo electrodes. The electronic component of the collector current was found to go up to 18% of the discharge current in a relatively low magnetic field and with a low anode voltage. The large electron-collector current is attached to the high value of the secondary ion-electron emission from the Al cathodes. A sharp minimum of the electron-collector current was found under certain conditions for a structure with Mo electrodes in a narrow range of the magnetic field.