Niobium (V) peroxocomplexes as a catalyst of oxidation of methylphenylsulphide by hydroperoxide

The electrospray ionization-mass spectrometry (ESI-MS) method has been used for determination of the structure of niobium peroxocomplexes. The formation of mono- and bisperoxocomplexes has been established. These complexes contain Schiff bases and 8-quinolinol as ligands. Trisperoxocomplexes are formed when pyridine and 1,10-phenanthroline are used. Peroxocomplexes with Schiff bases as ligands has shown a high activity as catalysts in the methylphenylsulphide oxidation.     

Energetic characterization of malt bagasse by calorimetry and thermal analysis

This study evaluates the thermal behavior of bagasse malt fresh and its heat capacity by means of calorimetry for samples with different moisture contents (50, 40, 30, 20, and 15 %). Chemical analysis was used to determine the content of volatiles, fixed carbon, and ash. The thermal degradation of malt bagasse presents two mass loss steps attributed to the release of moisture and to the decomposition of organic material. The calorific value of bagasse malt showed variation with moisture reduction as expected. Also showed variation with density. It was found a high percentage of volatile materials and the low percentage of ash and fixed carbon.     

Evaluation of the stability of ethanol in water certified reference material: measurement uncertainty under transport and storage conditions

This study simulated the transport and storage conditions of ethanol in water certified reference material (CRM) produced by the Chemical Metrology Division of Inmetro—DQUIM with the purpose of estimating the measurement uncertainty related to stability. The short-term stability study was performed on five different mass fractions (w) in terms of mg ethanol/g solution of the ethanol in water CRM. The nominal values are w = 0.5, 0.9, 1.1, 3.8 and 4.6 mg/g, at temperatures of 4 and 60 °C. On the other hand, the long-term stability study was developed on four different mass fractions (nominal values): w = 0.5, 0.9, 1.1 and 4.6 mg/g, at a temperature of 20 °C. This paper will show the data from the long-term stability study that took place over 52 weeks. The method used complies with ISO Guide 35, the BCR Guideline for Feasibility Studies and ISO Guide 34. According to the statistical parameters used in both studies, the stability of ethanol in water CRM was confirmed for all of the mass fractions studied.     

Optimization of gamma activation autoradiography for searching noble methods in samples of ultrabasic rocks

The conditions for the gamma activation autoradiography of some noble metals are optimized by selecting electron energy upon irradiation with bremsstrahlung from a U-17 linear electron accelerator (Moscow Engineering Physics Institute). Two ultrabasic rocks are taken as examples. It is shown that the reduction of electron energy from 25 to 15 MeV lowers the detection limits for some platinum-group metals and gold in such samples to the level attained at an electron energy of 25 MeV in the absence of background radiation. In one of the samples (Gal’mano-Enansk massif, Kamchatka), we detected an inclusion that can be due to the presence of (0.18 ± 0.03) ng Au or (8.4 ± 1.4) ng Pt. The detection limits (ng) are as follows: Au, 0.03; Pt, 0.16; Pd, 0.42, and Rh, 3.4.     

On the pairing of electrons in superconductors

National Center of Scientific Research, Vietnam. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vo. 78, No. 2, pp. 314–319, February, 1989.     

Quality assessment of hydrosphere in the vicinity of Czech nuclear power plants by radioanalytical methods

Summary The paper deals with the impact of nuclear plants and radioactive waste disposal on surface and ground water quality in their vicinity using various radiometric and radioanalytical methods. The impact of nuclear power plant Temelin on activation concentrations and fission products in hydrosphere, including tritium, was detected. The annual average tritium concentrations in Vltava River correspond to the previously calculated estimates for average and minimal quaranteed flow rates. The concentrations histories of ⁹⁰Sr and ¹³⁷Cs in surface water show a decreasing trend. This trend was not influenced by the nuclear power plant pilot operation. In the case of tritium, a concentration increase trend has been already observed since the startup of pilot operation. An attempt has made interpreting the sorption and diffusion data for radionuclides of cesium, strontium and tritium and technetium as representatives of multivalent elements. Sorption and diffusion data of ¹³⁷Cs and ⁹⁰Sr in contact with natural sorbent bentonite lead to the conclusion that both diffusion and batch sorption experiments can be simulated by an exchange model. Sorption of technetium on various bentonites plus additives materials is described. Retention of technetium on these solid phases is driven by sorption of reduced form of technetium Tc(IV).     

Separation of niobium and tantalum by extraction chromatography with bis(2-ethylhexyl)phosphoric acid

A novel method is developed for the reversed-phase extractive chromatographic separation of niobium and tantalum with bis(2-ethylhexyl)phosphoric acid. Niobium is extracted from 1-10M hydrochloric acid and can be stripped with 3M sulphuric acid containing 2% hydrogen peroxide. Tantalum is extracted from 0.1-2M hydrochloric acid and can be stripped with 0.1M hydrochloric acid containing 2M tartaric acid. It is possible to separate niobium and tantalum, in different ratios, from multicomponent mixtures.     

Effect of Diets,Familial History,and Alternative Therapies on Genomic Instability of Breast Cancer Patients

This study evaluates a correlation between family history, micronutrients intake, and alternative therapies with genetic instability, before and during breast cancer treatment. For this study, a total of 150 women were selected. Among those, 50 women were breast cancer patients on chemotherapy, while 50 breast cancer patients were on radiotherapy, and 50 were healthy females. All the participants signed the informed consent form and answered the public health questionnaire. Samples of buccal epithelial and peripheral blood cells were collected and analyzed through micronucleus and comet assays. The cells were evaluated for apoptosis and DNA damage. Results showed the association of patients’ family history with an increase in toxicogenetic damage before and during cancer therapy. On the other hand, patients with late-onset cancer also presented genetic instability before and during therapy, along with those who did not take sufficient vegetables and alternative therapies. A positive correlation was observed between the genetic instability and alternative therapies, while inverse correlation was recorded with the vegetable consumption. Results clearly explain that the nutritional aspects and alternative therapies influence the genetic instability before and during cancer therapies especially in radiotherapy treated patients. Our data could be used for the monitoring therapies and management of breast cancer patients.

     

CARBEX process,a new technology of reprocessing of spent nuclear fuel

Advances in the CARBEX process, a new aqueous chemical method for reprocessing of spent nuclear fuel (SNF) in carbonate media, are considered. A review of carbonate methods for SNF reprocessing is given. The CARBEX process concept is presented and experimental data for every stage of the CARBEX process: high-temperature oxidation of spent fuel composition, its oxidative dissolution in carbonate aqueous solutions, extraction refining of U(VI) and Pu(VI), solid-phase re-extraction of carbonate complexes of U(VI) and Pu(VI), and obtaining of uranium and plutonium dioxide powders for fabrication of ceramic nuclear fuel, are discussed. It was shown that the CARBEX process can be more effective and safe than the well-known industrial PUREX process.