New radon and gamma device using TLD and SSNTD to carry out monitoring in the environment

The research program, that we are leading, concerns and takes into consideration the potential risk of the natural and artificial radio-elements in the environment and particularly to consider their migration from environment to the people and with special respect to radon effects. To begin these investigations, we developed a new passive detectors using two solid nuclear track detector techniques: thermo-luminescent detectors (TLDs) (gamma measuring) and solid state nuclear track detectors (SSNTDs) (alpha measuring). The characteristics of the cell provide for alpha (SSNTD - LR115) and gamma-radioactivity (TLD-CaSO₄:Dy) measuring in different soil depths. The used technologies are with a low priced. The instrumentation has been first validated in laboratory to quality precisely its response and then, we have performed the survey for one site in Bulgaria.     

The proton g9/2 isomer in theN=50 nucleus87Rb and M2 transition rates in85,87Rb

Low-lying states of theN=50 nucleus⁸⁷Rb have been investigated in the (, ') reaction measuring- and delayed-rf-coincidences. A half-life ofT _1/2=6(1) ns was obtained for the level at 1578.1 keV. This experimental result confirms the 9/2⁺ assignment and the proton 1g_9/2 single-particle character of this state. Experimental M2 transition strengths in^85,87Rb are compared with predictions of the shell model and the particle-core coupling model.This work was partly supported by the Bulgarian National Research Foundation.     

Tautomerism in 5-Bromouracil: Relationships with Other 5-Haloderivatives and Effect of the Microhydration

A comparative analysis on the effect of the water on the molecular structure and spectroscopy of 5-halogenated uracils was carried out. Solvent effects were considered by using a variable number (1–10) of explicit water molecules surrounding the 5-halouracil derivatives in order to simulate the first hydration shell. More than 300 cluster structures with water were analyzed. B3LYP and MP2 quantum chemical methods were used. For cases where literature data are available, the computed values were in good agreement with previous experimental and theoretical studies. Several general conclusions were underlined.     

Effect of high-energy milling and thermal treatment on the solid-phase reactions in apatite–ammonium sulphate system

The phosphorous fertilizers are a product of natural sedimentary phosphorite ores. Using this raw material to produce phosphoric acid and classic phosphorous fertilizers has generated well-known ecological problems. A new and perspective way to use the same materials is creating a new type of time-delayed fertilizers applying high-energy milling (HEM) activation method. The impact of the mechanical forces over the solids is mostly revealed through the changes of the quantities being related to the energetic stability and reactivity of the solid phase. The aim of this work is to report the results from the investigation on the chemical and thermal reactions in composites of natural apatite , which are HEM activated for different times and thermally treated, (from Tunisia) and ammonium sulphate. The Tunisian phosphorite belongs to the ‘basic’ apatites having a Ca/P ratio of 1.70–1.77 and is characterized by a complex mineral composition with major component carbonate-fluorapatite. The used ammonium sulphate—(NH₄)₂SO₄ is obtained as a by-product from cleaning industrial waste gases, using e-beam technology. The composites of Tunisian phosphorite ores and ammonium sulphate, mixed in a mass ratio 1:1, were HEM activated during 10 min to 50 h with 20 mm Fe-milling bodies and temperature treated up to 1,100 °C. As a result, the chemical properties of the treated composites changed. Proofs were found for (i) formation of new phases during HEM activation such as NH₄Ca(PO₃)₃ (NH₄)₂CaH₄(P₂O₇)₂, (NH₄)₂Ca₃(P₂O₇)₂.6H₂O, CaH₂P₂O₇ and α-Ca₂P₂O₇; and (ii) decreasing of temperature intervals of phase changes in comparison to untreated composite.     

Vibrational characterization and prooxidant activity of newly synthesized dysprosium(III) complex

The dysprosium(III) complex of 5-aminoorotic acid (HAOA) was synthesized by reaction of the respective inorganic salt in amounts equal to ligand, molar ratio of 1:3. The structure of the complex was determined by means of elemental analysis, FTIR and FT-Raman spectroscopies. Significant differences in the IR and Raman spectra of the complex were observed as compared to the spectra of the free ligand. Detailed vibrational analysis of HAOA and Dy(III)-AOA systems revealed that the binding mode in the complex was bidentate through the carboxylic oxygen atoms. Dy(III) complex of 5-aminoorotic acid (DyAOA) exhibited prooxidant properties in the presence of the model system X/XO. In the DyAOA complex, the ion diminished the antioxidant properties of the AOA ligands.     

Theoretical and spectroscopic study of 2-substituted indan-1,3-diones: a coherent picture of the tautomeric equilibrium

The structures of some 2-substituted indan-1,3-diones are investigated in the gas phase and solution using quantum chemical calculations and spectral (NMR, IR, and UV) measurements. The influence of the substituent at the 2-position on the tautomeric equilibrium of 2-substituted indan-1,3-diones in solvents with different polarity is evaluated. It is shown that the equilibrium in 2-formyl-indan-1,3-dione and 2-acetyl-indan-1,3-dione is shifted to the 2-hydroxyalkylidene-indan-1,3-dione tautomer, while 2-carboxyamide-indan-1,3-dione exists as a mixture of two tautomers, 2-(hydroxyaminomethylidene)-indan-1,3-dione and 2-carboamide-1-hydroxy-3-oxo-indan, with extremely fast proton transfer between them. The situation for 2-carboxy-indan-1,3-dione is quite different - on the basis of the analysis of the obtained results, the possible existence of an anionic form of 2-carboxy-indan-1,3-dione in solution can be inferred.     

The electron impact mass spectra of some rotenoid derivatives

The fragmentation behaviour of several rotenoids functionalized in the alicyclic portions of the molecule is described.     

Extraction-radiochemical study of the ion-association complex of antimony (V) with tetrazolium violet and its thermal behavior

The optimum conditions for extraction of ion-associated complexes (IAC) formed from the tetrazolium salt-tetrazolium violet and Sb(V) in hydrochloric acid medium have been studied. An isotope of antimony (¹²⁵Sb) was used for determination of the recovery factor (R%) and distribution ratio (D_Sb). The thermal behavior of the antimony complex with tetrazole violet was studied using differential thermal and thermogravimetric analysis.     

Interaction of hydrogen sulfide with molybdophosphoric heteropolyacid

The effect of hydrogen sulfide on P–12Mo heteropolyacid has been studied using ESR, IR spectroscopic and thermal analysis methods. It has been established that hydrogen sulfide can be chemisorbed like water and no entering of sulfur into the anion structure takes place.

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