The structure of nanodiamond water dispersions prepared under different conditions was investigated by small-angle neutron scattering at the scale of 1 to 100 nm. The study of diluted dispersions was regarded as of paramount importance. Similarly to previous studies, strong clustering of particles was revealed in the solutions. The typical size of clusters (40 nm and above) depends on the modification of the dispersions. A common property can be distinguished for different systems: the fractal dimension of the clusters is in the range of 2.3?C2.4, which indicates that there is a common clustering mechanism in such systems. Using contrast variation, the existence of a nondiamond component in the colloidal particles of the dispersions was confirmed; it correlates with the presence of a graphene shell on crystallite surfaces. 相似文献
The structure of filament amyloid aggregates of hen egg white lysozyme in water has been investigated by the small-angle X-ray scattering method. The experimental data are described by different cylindrical models, among which the best agreement is reached with the long helix model. A comparison of the results with the small-angle neutron scattering data reveals the influence of the heavy component of the solvent (a H2O/D2O mixture) on the structure of the filaments. 相似文献
Pressure‐induced charge transfer from Bi to Ir/Ru is observed in the hexagonal perovskites Ba3+nBiM2+nO9+3n (n=0,1; M=Ir,Ru). These compounds show first‐order, circa 1 % volume contractions at room temperature above 5 GPa, which are due to the large reduction in the effective ionic radius of Bi when the 6s shell is emptied on oxidation, compared to the relatively negligible effect of reduction on the radii of Ir or Ru. They are the first such transitions involving 4d and 5d compounds, and they double the total number of cases known. Ab initio calculations suggest that magnetic interactions through very short (ca. 2.6 Å) M M bonds contribute to the finely balanced nature of their electronic states. 相似文献
The magnetotransport properties of Cox(Al2On)100 ? x nanocomposites were studied in a wide concentration range (34 ≤ x ≤ 74 at %). Negative tunnel magnetoresistance reaching 6.5% in a field of 10 kOe was established. In addition to the negative magnetoresistance, the Cox(Al2On)100 ? x composites were found to exhibit positive magnetoresistance reaching 1.5% in fields of 10 kOe over the concentration range corresponding to the percolation threshold (54 ≤ x ≤ 67 at %). The positive magnetoresistance is assumed to be due to the simultaneous existence in the composite structure of clusters and individual nanoparticles characterized by different values of the magnetic anisotropy and due to the dipole-dipole interaction between the clusters and nearest neighbor particles. 相似文献
Transport properties of perovskite-type Sr11Mo4O23 and composite Sr11Mo4O23 - 1 wt% Al2O3 were studied at 400–1300 K in the oxygen partial pressure range from 0.21 down to 10−19 atm. The electromotive force and faradaic efficiency measurements, in combination with the energy-dispersive spectroscopy of the fractured electrochemical cells, unambiguously showed prevailing role of the oxygen ionic conductivity under oxidizing conditions. At temperatures above 600 K, protonic and cationic transport can be neglected. The oxygen ion transference numbers vary in the range of 0.95–1.00 at 973–1223 K. At temperatures lower than 550 K, the total conductivity of Sr11Mo4O23 - 1 wt% Al2O3 composite measured by impedance spectroscopy tends to increase in wet atmospheres, thus indicating that hydration and protonic transport become significant. Reducing oxygen partial pressure below 10−10–10−9 atm leads to a significant increase in the n-type electronic conduction. The average thermal expansion coefficients in oxidizing atmospheres are (14.3–15.0) × 10−6 K−1 at 340–740 K and (18.3–19.2) × 10−6 K−1 at 870–1370 K.
Russian Chemical Bulletin - A new monomer containing thermosetting groups of two types, namely, propargyl ether and phthalonitrile, in the structure of the molecule was synthesized and studied. It... 相似文献
The possibility of controlled cyclic deflagration-to-detonation transition within a length of 2.5–3.0 m in an open-end tube
(94 mm in diameter) with separate continuous supply of natural gas and air was demonstrated for the first time. Based on experimental
studies, a workable pulse detonation burner, a prototype of new generation of industrial burners, was developed. It can produce
a combined effect on the objects blown on with combustion products—shock-wave (mechanical) and thermal. 相似文献
Based on detailed kinetic calculations and experimental data, it is demonstrated that the emission of nitrogen oxides from
detonation burner units (DBUs) is significantly lower than that from powerful conventional burners with similar characteristics.
Under certain conditions, realized largely in DBUs with rotating detonation, the main component of the nitrogen oxides may
turn out to be N2O. 相似文献
Poly(ethylene glycol) (PEG)-containing magnetic fluids - magnetite (Fe3O4) stabilized by sodium oleate - were prepared. Magnetic measurements confirmed superparamagnetic behaviour at room temperature. The structure of that kind of magnetic fluid was characterized using different techniques, including electron microscopy, photon cross correlation spectroscopy and small-angle neutron scattering, while the adsorption of PEG on magnetic particles was analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. From the in vitro toxicity tests it was found that a magnetic fluid containing PEG (MFPEG) partially inhibited the growth of cancerous B16 cells at the highest tested dose (2.1 mg/ml of Fe3O4 in MFPEG). 相似文献
An extension of method of horizontal rays and vertical modes developed for underwater acoustics to the spatially inhomogeneous anisotropic electrodynamic problem is proposed.Leningrad State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 7, 790–797, July, 1991. 相似文献