Non-reactive metal/semiconductor interfaces: a combined AES,AFM andPAC study

Thin In films on Ge(100), Si(100) andSi(111) are investigated using Auger-electron spectroscopy (AES), atomic force microscopy (AFM) andperturbed -angular correlation (PAC) spectroscopy, respectively. The growth mode of the metal films is characterized by in situ AES measurements, indicating distinct differences between the different substrate surfaces. Additional AFM investigations are used to monitor the film topography at higher metal coverage. Finally, the local crystalline structure of the films is studied by the PAC technique.     

A universe of Friedmann type with pressure

We propose a method of obtaining homogeneous and isotropic cosmological models satisfying physical conditions for 0 and . The model obtained in this way describes a universe filled with matter, the equation of state of which changes in time from the asymptotically ultrarelativistic to the asymptotically dust state.Dnepropetrovsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 8–12, May, 1993.     

Non-Archimedean superfields

The component representation of superfields over non-Archimedean (and, in particular, p-adic) superalgebras with an infinite number of anticommuting generators is investigated. It is shown that supersmooth fields, nonpolynomial in anticommuting variables, exist in the non-Archimedean case (as opposed to the real or complex case). The superfield representation for the algebra of non-Archimedean supersymmetries is analyzed in the p-adic case (p 3 mod 4). New solutions of equations on a chiral superfield and other superfield equations are discovered in non-Archimedean theory.This work has been supported by the CNR Fund (Italy) and an Advanced Study of p-Adic Mathematical Physics Grant.Institute of Electronic Engineering, Moscow. Genova University, Italy. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 35–38, November, 1993.     

HPLC determination of pyroglutamic acid as a degradation product in parenteral amino acid formulations

Summary The aminoacid glutamine in aqueous solution and in conditions of high temperature and long term storage is partly transformed into pyroglutamic acid which exhibits potential neurotoxic effects.Commercially available aminoacid mixtures supplemented with glutamine are heat-sterilized and some losses of glutamine and formation of pyroglutamic acid may occur.The aim of the work was to set up an easy and reliable HPLC method which allows the determination of pyroglutamic acid as a degradation product of glutamine. The column was a 5 m Hypersil ODS (100×4.6 mm) and the mobile phase 100% 0.007 M phosphate buffer pH 3.5.Stability studies in different conditions of temperature and time of storage were performed on aminoacid mixture available in the commerce.     

Polyfunctional macroheterocycles. 7. Synthetic enzyme analogs. synthesis of 16- and 22-membered nitrogen and sulfur crown compounds containing exocyclic histamine and histidine fragments and carboxyl groups

The acid hydrolysis of 9,14-bis(2-methoxycarbonylethyl)-11-12-benzo-3,4-(4,5-dimethylbenzo)-10,13-dioxo-1,6-dithia-9,14-diazacyclohexadeca-3,11-diene leads to the corresponding 9,14-biscarboxy derivative. The reaction of 4,9,15,20-tetrakis-(2-methoxycarbonylethyl)-6,7,17,18-dibenzo-5,8,16,19-tetraoxo-1,12-dithia-4,9,15,20-tetraazacyclodocosa-6,17-diene with hydrazine hydrate and subsequent treatment with NaNO₂ gave the corresponding tetraazide. The reaction of this tetraazide with histamine and histidine leads to macroheterocycles, containing exocyclic histamine and histidine fragments.For Communication 6, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 130–133, January, 1993.     

Derivatives of isoquinoline. 30. Synthesis of 4-spirosubstituted dioxenoisoquinolines

Methods have been developed for the synthesis of 1,4-benzodioxanyl-6-ethylamine with cyclopentyl and tetrahydropyranyl substituents in the -position. These compounds have been used as starting materials for the synthesis of new heterocyclic systems, the 4-spirocyclosubstituted dioxinoisoquinolines.For Communication 29, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 677–680, May, 1993.     

Determination and statistical analysis of trace element and active constituent concentrations in the medicinal plant Eucalyptus camaldulensis Dehnh (E. rostratus Schlecht)

In the leaves of the medicinal plant Eucalyptus camaldulensis Dehnh (E. rostratus Schlecht) collected from different sampling areas of Greece the trace elements antimony, cesium, chromium, cobalt, iron, europium, rubidium, scandium, strontium, thorium and zinc were determined by Instrumental Neutron Activation Analysis. In the same samples, the essential oil was determined by steam distillation and the percent relative composition of the essential oil in 1,8-cineole, p-cymene, -pinene by gas liquid chromatography. Also the refractive index of the essential oil was determined by a refractometer. Statistical analysis included the calculation of the correlation coefficient. Multiple correlation and cluster analysis was applied to all analytical data. The results showed that the trace elements iron, chromium, cobalt and zinc are correlated with the variation of the concentration of essential oil in the examined plant. These four elements along with rubidium and essential oil content could be used for the separation of the samples into groups related to the sampling areas. Statistically significant correlation between active constituents and some trace elements and a linear negative correlation between 1,8-cineole and refractive index were found.     

Depth-profiling of organic layers on microparticles with SNMS

Summary Previous work on the quantification and localization of organically bound elements with plasma-based SNMS for the characterization of microparticles has been continued. Relative detection factors for 10 elements have been determined. Except for lead and bromine a principle proportionality to atomic ionization probabilities is shown. A moderate matrix dependence of less than 40% variation was found even when inorganic and organic materials are included. For depth calibration, erosion rates of organic materials were determined from the time interval necessary to sputter through planar single-layers and Langmuir-Blodgett multi-layer systems with known thickness, as well as from gravimetric powder measurements. Depth propagation rates were 0.7 nm·sec^–1 for polymers and 2.3 nm·sec^–1 for aromatic compounds, when 400 eV argon ion bombardment with 0.7 mA·cm^–2 was used. A depth resolution of 30 nm has been obtained. Model particles of 5 m size have been coated with fluoranthene. Inspection with SNMS revealed an incomplete coating covering only 20% of the microparticle surface with an average thickness of the partial coating of 300 nm. Subsequent characterization using laser-induced fluorimetry confirmed the amount of fluoranthene coating measured by SNMS.     

Trace element analysis of high-purity copper

Summary In copper samples trace impurities of the elements As, Bi, Cr, Fe, Pb, Sb, Se and Te in the low g/g range were coprecipitated with lanthanum hydroxide and determined by flame AAS (Fe) and electrothermal AAS (other elements). Reduction of the sample weight results in a considerable saving of time compared to elder procedures and allows to apply centrifugation instead of filtration as separation technique, by which the risk of contamination is decreased. The completeness of separation was examined by analyzing standard solutions. Additionally radio tracer experiments were employed with Sb and Se. Based on recovery data, a classification scheme was set up with regard to adsorption behaviour. High-purity copper samples were analyzed by the procedure described; INAA and ICP-MS were used as comparison methods. Parameters affecting the precision were examined; the main influence was caused by the separation step. The procedure is well suitable for the determination of 2–10 g/g As, Cr and Pb and 5–50 g/g Fe in high-purity copper.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday