Polarized fluorescence in investigation of rotational diffusion of the fluorescein family markers in bovine serum albumin solutions

The analysis of polarized fluorescence of the fluorescein family markers was conducted and parameters of their rotational diffusion in bovine serum albumin solutions (BSA) were determined. The degree of fluorescence anisotropy of the markers increases in the BSA solutions, as well as the time of rotational relaxation of the markers, while the rotational-diffusion coefficient of the markers decreases. The differences in the rotational-diffusion parameters between the markers are determined by the values of the electronegativity of the atoms in their structural formulas: the increase of the electronegativity of the atoms in the structural formulas of the markers results in the increase of the degree of fluorescence anisotropy, a decrease of the rotational-diffusion coefficient, and in the increase of the rotational-relaxation time both in the solutions without the protein and with BSA.     

Carbon‐Dot‐Decorated Nanodiamonds

The synthesis of a new class of fluorescent carbon nanomaterials, carbon‐dot‐decorated nanodiamonds (CDD‐ND), is reported. These CDD‐NDs are produced by specific acid treatment of detonation soot, forming tiny rounded sp² carbon species (carbon dots), 1–2 atomic layers thick and 1–2 nm in size, covalently attached to the surface of the detonation diamond nanoparticles. A combination of nanodiamonds bonded with a graphitic phase as a starting material and the application of graphite intercalated acids for oxidation of the graphitic carbon is necessary for the successful production of CDD‐ND. The CDD‐ND photoluminescence (PL) is stable, 20 times more intense than the intrinsic PL of well‐purified NDs and can be tailored by changing the oxidation process parameters. Carbon‐dot‐decorated DNDs are shown to be excellent probes for bioimaging applications and inexpensive additives for PL nanocomposites.     

The Modern Problems of Ultrafast Magnetoacoustics (Review)

Acoustical Physics - A review of modern lines of research in the field of ultrafast magnetoacoustics is presented. Effects of interaction of ultrashort (picosecond) acoustic pulses with a magnetic...     

Comparative studies of the features of the formation of impurity heterogeneity in GaSb:Te crystals in the case of directed crystallization under space and ground conditions

The results of comparative studies concerned with the formation of impurity heterogeneity in GaSb:Te crystals grown at the POLIZON facility by the Bridgman method under space and ground conditions are presented. Crystallization is carried out in the same temperature-time modes of the heaters: on board the Foton-M 3 spacecraft in space and by the vertical Bridgman method under conditions of weakened thermogravitational convection on Earth. In both cases, Marangoni convection is eliminated, and the effect of vibration microaccelerations on the ampoule that contains the melt is minimized. The microuniformity of the dopant distribution in the crystal areas that are recrystallized by the Bridgman method is higher than that in the seed grown by the Czochralski method. Microuniformity is higher under space conditions than under ground conditions with weakened thermogravitational convection. Spectral Fourier analysis of the spreading resistance distribution R _s reveals the characteristic periods of heat and mass transfer processes in the melts under ground and space conditions.     

Influence of solid-phase ferritization method on phase composition of lithium-zinc ferrites with various concentration of zinc

Methods of X-ray phase analysis (XRPA) and differential thermogravimetry in a magnetic field (DTG(M)) are used to investigate the phase composition of Li_0.5(1?x)Fe_2.5?0.5x Zn _x O₄ (x _Zn?=?0.2, 0.4, and 0.6) ferrite spinels synthesized at a temperature of 700?°C during 120?min by thermal annealing of a reagent mixture in a furnace and heating of the mixture using high-power beam of accelerated electrons with energy of 2.4?MeV. Thermal ferritization of all compositions leads to the formation of phases whose composition is close to simple monoferrites. Lithium?Czinc ferrite phases are formed during annealing under electron irradiation. It is concluded that the rate of controllable diffusion interaction of monoferrite phases significantly increases under conditions of high-power electron irradiation.     

Thin triangular blunt-nosed plate in a viscous hypersonic flow

The effect of a small blunt nose on the hypersonic flow past a thin, high-sweep and high-aspect-ratio plate at small incidence is investigated. The analysis is made by means of numerical simulation within the framework of the parabolized Navier-Stokes equations and the Euler equations in combination with approximate methods for calculating the heat transfer. The results are compared with the data of experiments in which some nontrivial features of the heat flux distributions over the thin plate surface were revealed.     

Concerning microsecond megaampere-current plasma opening switches

The operation mechanism of a microsecond megaampere-current plasma opening switch is considered. The magnetic field penetrates into the plasma via near-electrode diffusion. The increase in the degree of plasma magnetization due to electron heating results in an increase in plasma resistivity and current break. The problem of calculating a plasma opening switch is mathematically formulated. The problem reduces to simultaneously solving one-fluid two-temperature MHD equations with allowance for the Hall current and two-dimensional electric circuit equations. To analyze the solution obtained, one-dimensional equations are derived based on the assumption that the size of the electrode region in which the plasma is strongly magnetized is much smaller that the plasma column length. In this approximation, the operating modes of a plasma opening switch are studied numerically. On long time scales (≥2–3 μs), the operation is limited by plasma ejection from the interelectrode gap. On short time scales (≤1 μs), the dominant process is the penetration of the magnetic field with the current velocity. The results of the calculations are compared with the available experimental data. The developed concept and numerical procedure are used to optimize the scheme for an explosion experiment on breaking megaampere currents under conditions similar to those in the EMIR complex.     

The effect of impurity atoms on the multiplication of edge dislocations

The multiplication of edge dislocations in impurity atmospheres was studied. Impurities pin a dislocation line, so that additional stress must be applied to “drive” a multiplication mechanism. An expression for diffusion redistribution of impurity atoms along a dislocation segment due to the nonuniform chemical potential was derived. The early stage of moderate-temperature creep is qualitatively explained in terms of theoretical analysis.     

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

Possible approaches to synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐6‐carboxamides 4 have been discussed. It is shown that the preferable approach is cyclization of 2‐iminocoumarin‐3‐carboxamides 1 , utilizing 5‐amino‐3‐methyl‐N²‐arylthiophene‐2,4‐dicarboxamides 2 as binucleophilic reagents. The proposed procedure allowed us to easily obtain 4 in two stages, using common reagents. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:341–346, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20303     

On a Correlation between the Microcrystallite Radius and the Plasticity Factor

The ratio of the dimensionless radius of the microcrystallites in liquid metals and other liquids at melting point to the stated earlier plasticity factor has been estimated. A frequency distribution of this ratio for 24 substances, including some metals, liquid noble gases, and other non-metals, seems to be normal and characterized by dispersion 16.6, mean value 54, and mean error 13.5. So it was supposed, this ratio is a constant which may be used for calculation of the microcrystallite radius. Some consequences of this statement are discussed.