The investigation of EPR paramagnetic probe line width and shape temperature dependence in high-temperature superconductors of Bi–Pb–Sr–Ca–Cu–O system

The work is related with the finding out of magnetic phases in strongly anisotropic high-temperature superconductor Bi1,7Pb0,3Sr2Ca2Cu3O10-δ in the temperature region where the superconductor is in the normal state. It was studied the temperature dependence of the paramagnetic probe EPR line width. In the normal state at T\u3eTc near 175 K it was revealed a pick in the temperature dependence of line width. In this region it was observed the time increase of the line width with the characteristic time ~ 17 min. This shows the possibility of magnetic phase formation in this material

Synthesis of Gold Nanoparticles by Blue-Green Algae Spirulina Platensis

The synthesis of gold nanoparticles by one of the many popular microorganisms – blue-green algae Spirulina platensis was studied. The complex of optical and analytical methods was applied for investigation of experimental samples after exposure to chloroaurate (HAuCl4) solution at different doses and for different time intervals. To characterize formed gold nanoparticles UV-vis Spectrometry, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy-dispersive analysis of X-rays (EDAX) were used. It was shown that after 1.5 – 2 days of exposure the extracellular formation of nanoparticles of spherical form and the distribution peak within the interval of 20-30 nm took place. To determine gold concentrations in the Spirulina platensis biomass neutron activation analysis (NAA) was applied. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3496

MERCURY ADSORPTION BY ARTHOBACTER GLOBIFORMIS AND SPIRULINA PLATENSIS

Abstract. The increasing contamination of soil, sediment, and water with heavy metals by natural and industrial processes is a worldwide problem. Many bacteria and microalgae have demonstrated ability to absorb toxic elements. To study mercury biosorption by bacteria Arthrobacter globiformis and microalga Spirulina platensis neutron activation analysis (NAA) was applied. The process of mercury biosorption by these media was described by Freundlich and Langmuir-Freundlich Model. Both microorganisms showed a great potential to be used as biosorbing agents for mercury removal from the environment

Spectroscopic studies of defects in gamma- and neutron-irradiated magnesium aluminates spinel ceramics

The spectroscopic investigations of defects in optical spinel ceramics irradiated with gamma-rays from ⁶⁰Co source and mixed neutron-gamma field in WWR reactor to neutron fluences of 1·10¹³ and 5·10¹³ n/cm² were provided. The obtained data on the dose dependence of intensity of absorption bands in the visible range allow to identify the origin of optical centers formed under irradiation. Absorption in IR range indicates on the presence in ceramics carbon-related complexes that become active after irradiation. The registered EPR signal of g = (2.0174±0.0005) and width of (46.1±1.5) G which corresponds to HO₂⁻ or O₃⁻ radicals. The dependences of the investigated centers on annealing temperature of the irradiated spinel ceramics show unusual increase in intensity of absorption and steady-state radio-luminescence in the temperature range of 200…400 °C. The role of complexes of defects including anti-site defects in formation and healing of defects in different temperature ranges are analyzed taking into account different mobility of cations and anions and specific mechanism of radio-luminescence.Проведені спектроскопічні дослідження в оптичній кераміці шпінелі, опроміненій гамма-променями джерела ⁶⁰Co та змішаним гамма-нейтронним потоком у ВВР реакторі при потоках нейтронів 1·10¹³ та 5·10¹³ нейтр./см². Одержані дані із залежності інтенсивності смуг поглинання у видимій області дозволили ідентифікувати природу оптичних центрів, створених опромінюванням. Поглинання світла в інфрачервоній області вказує на присутність у кераміці комплексів, що містять вуглець та стають оптично активними після опромінення. Зареєстрований сигнал ЕПР з g = (2.0174 ±0.0005) і шириною (46.1±1.5) Гс, що відповідає HO₂⁻ - або O₃⁻ -радикалам. Залежність досліджених центрів від температури відпалу в опроміненій кераміці шпінелі демонструє незвичайне збільшення інтенсивності поглинання та стаціонарної люмінесценції в інтервалі температур 200…400 °C. Проаналізована роль комплексів дефектів, які включають дефекти антиструктури в створенні та відпалу дефектів у різних температурних областях з урахуванням різної рухливості катіонів та аніонів, а також специфіки механізму рентегнолюмінесценції.Проведены спектроскопические исследования оптической керамики шпинели, облученной гамма-квантами источника ⁶⁰Co и смешанным гамма-нейтронным потоком в реакторе ВВР при потоках нейтронов 1·10¹³ и 5·10¹³ нейтр./см². Полученные данные из зависимости интенсивности полос поглощения в видимой области позволили определить природу оптических центров, созданных облучением. Поглощение света в инфракрасной области указывает на присутствие в керамике углеродсодержащих комплексов, которые становятся оптически активными после облучения. Зарегистрированный сигнал ЭПР с g = (2.0174 ±0.0005) и шириной (46.1±1.5) Гс, соответствующий HO₂⁻ - или O₃⁻ -радикалам. Зависимость концентраций исследованных центров от температуры отжига в облученной керамике шпинели демонстрирует необычный рост интенсивности поглощения и стационарной люминесценции в интервале температур 200…400 °C. Проанализирована роль комплексов дефектов, которые включают дефекты антиструктуры в образовании и отжиге дефектов в различных температурных областях с учетом различной подвижности катионов и анионов, а также специфики механизма рентгенолюминесценции

SYNTHESIS OF GOLD NANOPARTICLES BY BLUE-GREEN ALGAE Spirulina platensis

Kalabegishvili T. et al. E14-2012-31 Synthesis of Gold Nanoparticles by Blue-Green Algae Spirulina platensis The synthesis of gold nanoparticles by one of the many popular microorganisms Å blue-green algae Spirulina platensis was studied. The complex of optical and analytical methods was applied for investigation of experimental samples after exposure to chloroaurate (HAuCl4) solution at different doses and for different time intervals. To characterize formed gold nanoparticles UV-vis, TEM, SEM, EDAX, and XRD were used. It was shown that after 1.5Ä2 days of exposure the extracellular formation of nanoparticles of spherical form and the distribution peak within the interval of 20Ä30 nm took place. To determine gold concentrations in the Spirulina platensis biomass, neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) were applied. The results obtained evidence that the concentration of gold accumulated by Spirulina biomass is rapidly growing in the beginning, followed by some increase for the next few days. The obtained substance of Spirulina biomass with gold nanoparticles may be used for medical, pharmaceutical, and technological purposes. The investigation has been performed a

EPITHERMAL NEUTRON ACTIVATION ANALYSIS FOR BACTERIAL TRANSFORMATIONS OF CHROMIUM

Most powerful primary analytical technique, neutron activation analysis, was applied to study indigenous bacteria, namely, Arthrobacter genera which can be successfully used in detoxification and immobilization of toxic substances. In the present study the effect of Cr(VI) on the elemental content of these bacteria has been examined. The concentrations from 12 to 19 elements such as Na, Al, Cl, K, Fe, Co, Zn, As, Br, Rb, Sr, Sb, Ba, Tb, Th, U were determined in the bacterial cells. The high rate of Cr accumulation in the tested bacterial cells was shown. In bacteria treated with chromate some similarity in the behaviour of the following essential elements − potassium, sodium, chlorine − was observed. Such non-essential elements as Ag, As, Br and U were determined in all bacteria and have to be considered by cells as toxins

PRELIMINARY RESULTS OF ATMOSPHERIC DEPOSITION OF MAJOR AND TRACE ELEMENTS IN THE GREATER AND LESSER CAUCASUS MOUNTAINS STUDIED BY THE MOSS TECHNIQUE AND NEUTRON ACTIVATION ANALYSIS

The method of moss biomonitoring of atmospheric deposition of trace elements was applied for the first time in the western Caucasus Mountains to assess the environmental situation in this region. The sixteen moss samples have been collected in 2014 summer growth period along altitudinal gradients in the range of altitudes from 600 m to 2665 m. Concentrations of Na, Mg, Al, Cl, K, Ca, Ti, V, Mn, Fe, Zn, As, Br, Rb, Mo, Cd, I, Sb, Ba, La, Sm, W, Au, and U determined by neutron activation analysis in the moss samples are reported. A comparison with the data for moss collected in Norway (pristine area) was carried out.  Multivariate statistical analysis of the results was used for assessment pollution sources in the studied part of the Caucasus. The increase in concentrations of most of elements with rising altitude due to gradually disappearing vegetation cover and wind erosion of soil was observed. A comparison with the available data for moss collected in the Alps at the same altitude (~ 2500 m) was performed.</p

MERCURY ADSORPTION BY ARTHOBACTER GLOBIFORMIS AND SPIRULINA PLATENSIS

The increasing contamination of soil, sediment, and water with heavy metals by natural and industrial processes is a worldwide problem. Many bacteria and microalgae have demonstrated ability to absorb toxic elements. To study mercury biosorption by bacteria Arthrobacter globiformis and microalga Spirulina platensis neutron activation analysis (NAA) was applied. The process of mercury biosorption by these media was described by Freundlich and Langmuir-Freundlich Model. Both microorganisms showed a great potential to be used as biosorbing agents for mercury removal from the environment