Effective Conductivity and Magnetic Permeability of Nanostructured Materials in Magnetic Field

The problem of homogenization the nanostructured materials placed in DC magnetic field has been discussed. The experimental data are obtained using metallic superlattices, metal-dielectric thin films and 3D-nanostructured materials. All these materials contain ferro- or ferrimagnetic component. The trans-mission and reflection coefficients were measured on the waves of millimeter waveband. It has been shown that the experimental frequency spectra of the coefficients in zero magnetic field can be described by the effective conductivity and dielectric permittivity. The spectra of ferromagnetic resonance, however, cannot be calculated correctly with the averaged magnetization. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3534

Effective Conductivity and Magnetic Permeability of Nanostructured Materials in Magnetic Field

The problem of homogenization the nanostructured materials placed in DC magnetic field has been discussed. The experimental data are obtained using metallic superlattices, metal-dielectric thin films and 3D-nanostructured materials. All these materials contain ferro- or ferrimagnetic component. The trans-mission and reflection coefficients were measured on the waves of millimeter waveband. It has been shown that the experimental frequency spectra of the coefficients in zero magnetic field can be described by the effective conductivity and dielectric permittivity. The spectra of ferromagnetic resonance, however, cannot be calculated correctly with the averaged magnetization. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3534

Preparation and structural stability of ordered nanocomposites: opal matrix - lead titanates

The conditions for the formation of nanocomposites based on the basis of lattice packings of SiO[2] nanospheres (opal matrices) with included crystallites of lead titanates (PbTiO[3] and PbTi[3]O[7]) in interspherical nanospacing are considered. For the formation of nanocomposites are used sample opal matrices with dimensions of single-domain regions >=0,1 mm.{3} The diameter of SiO[2] nanospheres was ~260 nm. Obtained nanocomposites volume >2 cm{3} in filling >20% of interspherical nanospacing PbTiO[3], PbTi[3]O[7] crystallites were size of 16-36 nm. Using X-ray diffraction and Raman spectroscopy are studied composition and structural stability when heated nanocomposites to 550°C, which allowed the identification of a local phase transition with change of the space group. The dependence of the composition of synthesized materials on the conditions of their preparation is submitted

Stress-induced MICA and MICB molecules in oncology

MICA and MICB molecules, MHC class I chain-related proteins, are expressed on the membranes of damaged, transformed or infected cells. These glycoproteins bind to the NKG2D receptor of NK cells, resulting in their activation and cytotoxic response against MICA- and/or MICB-expressing cells. Expression of NKG2D receptor ligands allows the elimination of tumor and damaged cells. Soluble forms of MICA/B proteins are produced as a result of protein cleavage. Binding of soluble ligands to NKG2D receptors causes their internalization and degradation, leading to a decrease in NK cell activity. Malignant growth of gastrointestinal tissues, pancreas, liver, kidney, lung, skin, and blood cancers is accompanied by increased concentration of soluble MICA/B in blood plasma of the patients. High concentrations of these proteins are associated with lower overall and recurrence-free survival in the patients. Soluble MICA/B contribute to immunosuppressive tumor microenvironment, and increase in their plasma contents is considered an index of tumor escape from the immune surveillance. The role of MICA/B protein changes during carcinogenesis is also under studies. At the early stage of tumor formation, these proteins contribute to activation of NK cells and elimination of transformed cells, whereas, at the later stage of this process, the increased production of its soluble forms leads to a decrease in anti-tumor activity of NK cells. Standard cancer treatment, such as chemotherapy, is accompanied by increased density of these molecules on the tumor cells. In addition, preclinical studies show that inhibition of MICA/B shedding with antibodies or their derivatives may also promote the anti-tumor activity of NK cells. This review summarizes basic information on the biology of MICA/B molecules, their expression by normal and transformed cells, elucidates the role of these molecules in anti-tumor immune surveillance, and provides information on the potential use of MICA/B in diagnosis and therapy of malignant diseases

ПОЛУЧЕНИЕ И ФИЗИЧЕСКИЕ СВОЙСТВА ОПАЛОВЫХ МАТРИЦ С НАНОЧАСТИЦАМИ ОКСИДОВ Fe И Ti

The article considers specific features of the formation of nanocomposites based on the lattice packing of SiO2 nanospheres (opal matrices) with clusters of titanium and iron compounds (FeTiO3, FeTi2O5, TiO2, Fe2O3) embedded into nanopores between spheres. For the formation of the nanocomposites samples of opal matrices with the sizes of single-domain regions > 0.1 mm3 were used. The diameter of the SiO2 nanospheres was ~260 nm. Nanocomposites with the volume > 1 cm3 and 10-15% of interspherical nanospacing filled by crystallites of titanium and iron compounds were obtained. The composition and structure of the nanocomposites were studied by electron microscopy, X-ray diffraction and Raman spectroscopy. The dependence of the composition of the synthesized materials on the conditions of their preparation is shown. Results of measurements of the frequency dependences (within the range 1 MHz - 3 GHz) of the magnetic and dielectric characteristics of the obtained nanostructures are presented. Hysteresis loops were studied for the obtained samples.Рассмотрены особенности формирования нанокомпозитов на основе решетчатых упаковок наносфер SiO2 (опаловых матриц), содержащих в межсферических полостях кластеры соединений титана и железа (FeTiO3, FeTi2O5, TiO2, Fe2O3). Для формирования нанокомпозитов использовали образцы опаловых матриц с размерами монодоменных областей > 0,1 мм3, диаметр наносфер SiO2 составлял ~260 нм. Получены нанокомпозиты объемом > 1 см3 с заполнением 10-15% объема межсферических полостей кристаллитами соединений титана и железа. Изучены состав и строение нанокомпозитов с использованием электронной микроскопии, рентгеновской дифрактометрии и спектроскопии комбинационного рассеяния света. Показана зависимость состава синтезированных веществ от условий их получения. Представлены результаты измерений частотных (в диапазоне 1 МГц - 3 ГГц) зависимостей магнитных и диэлектрических характеристик полученных наноструктур. Проведены исследования петель гистерезиса для полученных образцов

СТРОЕНИЕ И ДИЭЛЕКТРИЧЕСКИЕ СВОЙСТВА НАНОКОМПОЗИТОВ: ОПАЛОВЫЕ МАТРИЦЫ - ОКСИДЫ ТИТАНА И ТИТАНАТЫ РЕДКОЗЕМЕЛЬНЫХ ЭЛЕМЕНТОВ

The conditions for the formation of nanocomposites based on the basis of lattice packings SiO2 nanospheres (opal matrices) with included clusters of crystalline phase of titanium oxide (TiO2 and TiO) and rare-earth titanates of the general formula R2TiO5 or R2Ti2O7, where R - Er, Dy, Gd, Pr, Tb and Yb in interspherical nanospacing are considered. The composition and structure of the nanocomposites studied electron microscopy, X-ray diffraction and Raman spectroscopy. Results of measuring of the frequency dependences of real and imaginary components of the permittivity and microwave conductivity (ranging 10-2-1012 Hz) obtained nanostructures are viewed.Рассмотрены особенности формирования нанокомпозитов на основе решетчатых упаковок наносфер SiO2 (опаловых матриц), содержащих в межсферических полостях кластеры кристаллических фаз оксидов титана (TiO2 и TiO) и титанатов редкоземельных элементов состава R2TiO5 или R2Ti2O7, где R - Er, Dy, Gd, Pr, Tb и Yb. Методами электронной микроскопии, рентгеновской дифрактометрии и спектроскопии комбинационного рассеяния света изучены состав и строение нанокомпозитов. Приведены результаты измерений частотных зависимостей действительной и мнимой компонент диэлектрической проницаемости, а также микроволновой проводимости (в диапазоне 10-2-1012 Гц) полученных наноструктур