THE INFLUENCE OF EXTRACTION PROCESS PARAMETERS OF SOME BIOMATERIALS PRECURSORS FROM HELIANTHUS ANNUUS

Solvent extraction, microwave-assisted extraction (MAE) and ultrasonic extraction (UE) was used for to extract phenolic compounds and amino acid from sunflower seeds. The influence of extraction process parameters (time, temperature, and the type of solvent (water and methanol) on the isolation of biological compounds was studied. The obtained extracts were qualitatively evaluated by chromatographic methods: HPLC, GC-MS, and spectroscopic methods: FT-IR, UV-VIS spectroscopy. It was shown that by microwave extraction were isolated free amino acids and phenolic compounds

THE EFFECT OF TiO2 NANOPARTICLES (DOPED OR NOT WITH Ag, ENCAPSULATED OR NOT IN LYPOSOMES), ON THE SPLEEN ULTRASTRUCTURE IN Mus musculus SPECIES, EXPOSED AT A STRESS FACTOR X-RAYS

The present experiment was performed on young females of Mus musculus, 22-24 g each, intraperitoneal injected with a suspension of titanium dioxide (five injections of 0.5 ml each, one at two days, with 0.01% TiO2 or TiO2-Ag suspension). The TiO2 nanoparticles of anatase crystallization form, 10-20 nm size, wereconjugated or not with 1% Ag, encapsulated or not in lyposome. A day after the third injection, half of theanimals received a sublethal dose of X-rays (2.58 Gy; the stress factor). A day after the last injection, the animals were sacrificed through the section of thecarotid artery. Ultrastructural investigations were performed at the spleen level. The analysis of the ultrastructural features from the spleen level enabledthe following observations: the single action of the TiO2 or TiO2-Ag nanoparticles induced an inflammatory process, but in the presence of X-rays, they manifested a slight protective effect; the TiO2-Ag nanoparticles, encapsulated in liposome, manifested a strong radioprotective effect, but the endocapsulation process is not optimal and has to be improved; the presence of a protective effect at the spleen level can suggest that the TiO2-Ag nanoparticles can be used to enhance the organism resistance in case of carcinogenic treatment (in animal or in homo)

Plane-elliptical mirror furnace for crystal growth

For single crystal growing in aggressive media, classical heating methods do not provide reliable results. In this study, we conceived and realized a system for radiant heating, by which the growth media is separated by the radiant and radiation focusing elements. The system is composed from an assembly of plane-elliptical mirrors with rod-shaped halogen lamps in the first focal centers and crucible as the second focal center. The growth medium being isolated, we could employ highly oxidant atmospheres and use crucibles made of dielectric oxide materials. The results obtained show a possibility to use the system to synthesize materials in aggressive media, as well as to configure the specific temperature gradients required by these processes.Классические методы нагрева не обеспечивают надежных результатов при выращивании монокристаллов в агрессивных средах. В этом исследовании нами разработана и реализована система для радиационного нагрева, с помощью которой достигается отделение ростовой среды от излучающих и фокусирующих излучение элементов. Система состоит из плоско-эллиптических зеркал с галогеновыми лампами стержневидной формы в первых фокальных центрах и тиглем во втором фокальном центре. Поскольку ростовая среда изолирована, возможно применение сильно окислительных сред и использование тиглей из диэлектрических оксидных материалов. Полученные результаты иллюстрируют возможность применения системы для синтеза материалов в агрессивных средах, а также для конфигурирования специальных систем градиентов темпера-Класичні способи нагрiвання не забезпечують надійних результатів при вирощу-вйнні монокристалів в агресивних середовищах. У цьому дослідженні розроблено та реалізовано систему для радіаційного нагріву, за допомогою якої досягається відділення ростового середовища від випромінювальних та фокусувальних елементів. Система складається з плоско-еліптичних дзеркал з галогеновими лампами стрижневої форми у перших фокальних центрах та з тиглем у другому фокальному центрі. Оскільки ростове середовище ізольоване, можливим є застосування сильно окиснювальних середовищ та використання тиглів з діелектричних оксидних матеріалів. Отримані результати посвідчують можливість застосування системи для синтезу матеріалів в агресивних середовищах, а також для формування спеціальних систем градієнтів температури, необхідних для таких процесів

The Electrical Properties of Some Composite Materials Based on Sodium and Tantalum Oxides

Two samples of Na-Ta oxides were synthesized by the hydrothermal method at reaction temperatures of 160°C (sample A) and 200°C (sample B). For reference, a third sample of pure NaTaO₃ was prepared by the sol-gel method (sample C). Using X-ray diffraction, scanning electron microscopy, UV-vis diffuse reflectance spectra and electric measurements, structural, morphologic, spectroscopic and electric properties of samples were investigated. The structural characterization by X-ray diffraction revealed that samples A and B are mixtures of Na-Ta oxides (including NaTaO₃ and other compounds), whilst sample C is pure NaTaO₃. UV-vis diffuse reflectance spectra allowed evaluation of the band gap energy $(E_{g})$, resulting in 3.88 eV for sample A, 3.93 eV for sample B and 4.1 eV for sample C. Electrical resistivity measurements, over the temperature range 300-450 K, showed a typical semiconductor behavior of the investigated samples, with the effective activation energy, $E_{a}$ of 0.47 eV (sample A), 0.45 eV (sample B) and 0.82 eV (sample C). Based on the Mott variable range hopping model, the conductivity mechanism in the investigated samples was analyzed. The results shown that the density of states at the Fermi-level, $N(E_{F})$ is constant in the investigated temperature range and the typical values of $N(E_{F})$ are $0.713 \times 10^{18} eV^{-1} cm^{-3}$ (sample A), $0.621 \times 10^{18} eV^{-1} cm^{-3}$ (sample B) and $0.855 \times 10^{17} eV^{-1} cm^{-3}$ (sample C). Other parameters of VRH model such as the hopping distance R and the hopping energy W have also been computed and the following values at the room temperature were obtained: R=15.7 nm and W=86 meV (for sample A); R=16.3 nm and W=89 meV (for sample B) and R=26.7 nm and W=147 meV (for sample C)

Synthesis of lithium cobalt oxide by single-step soft hydrothermal method

Lithium cobalt double oxide LiCoO2 was synthesized at 220 °C by soft hydrothermal method using Co(OH)2 and LiOH as precursors, LiOH/NaOH as mineralizers and H2O2 as oxidant. The soft hydrothermal synthesis method offers the dual advantage of a much lower synthesis time and a higher purity in comparison with other synthesis methods. The compound was identified by X-ray diffraction and its purity was checked by magnetic and electron magnetic resonance measurements. The grain morphology was studied by Scanning Electron Microscopy and an exponential growth of particle size with synthesis time was observed

Thermal diffusivity measurements using open photoacoustic cell technique

The application of open photoacoustic cell (OPC) technique is demonstrated for measuring thermal diffusivity of solid samples. It is based upon the measurement of the photoacoustic signal in the modulation frequency region where the thermal diffusion length equals to the sample thickness. The measurements were carried out at room temperature for gold alloys (Au0 75Ag0.and Au. Ag. ); epoxidised natural rubbers 25 0 50 0 50 [ENR  25  (75%C )  and  ENR  50  (75%C)];  and  supercond ucti ng  ceramics (Bi2Pb0 .6 Sr2Ca1.94Ba 0. Cu 0 ,  and Bi Pb . Sr Ca1. Zn. Cu 0 ) . The thermal 06          3       8 2         0 6       2 93         0 07          3       8 diffusivity values obtained in this measurement were in the range of 0.97 for Al down to 1.61 x 10-3 cm2/s for polymer sample