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41.
Multiwalled carbon nanotubes were modified by carboxy groups. Four independent methods for the determination of the degree
of functionalization of the surface were proposed: 13C NMR spectroscopy, thermogravimetry, titrimetry, and fluorimetry. The first two methods show the total content of carboxy
groups in the sample, and the latter two methods give information about the content of the surface groups only.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 291–295, February, 2008. 相似文献
42.
The effective signal in x-ray diffraction analysis of material properties often contains high frequency (noise) and low frequency
(trend) components as additive parts. It is necessary to extract the effective signal from the noise to ensure high quality
of signal processing. Digital filters of Volterra type are proposed for filtering purposes and a comparison of Volterra filtration
implemented on x-ray diffraction data versus results from a set of other digital filters is given. 相似文献
43.
S. O. Konorov E. E. Serebryannikov A. A. Ivanov D. A. Akimov M. V. Alfimov A. M. Zheltikov 《JETP Letters》2004,79(9):395-398
Hollow-core photonic-crystal fibers with a special dispersion profile are shown to allow phase-matched nonlinear optical interactions of isolated air-guided modes of high-intensity femtosecond laser pulses confined in the hollow fiber core. We present theoretical and experimental studies of the four-wave mixing of fundamental and second-harmonic pulses of a Cr:forsterite laser with an initial pulse duration of about 50 fs and an intensity on the order of 1014 W/cm2 in waveguide modes of a hollow photonic-crystal fiber with a core diameter of about 13μm. 相似文献
44.
A. A. Mukhin V. Yu. Ivanov V. D. Travkin S. P. Lebedev A. Pimenov A. Loidl A. M. Balbashov 《JETP Letters》1998,68(4):356-362
The electrical conductivity, magnetic susceptibility, magnetization, and submillimeter (v=5∓20 cm−1) permittivity and dynamic conductivity of La1−x
Sr
x
MnO3 (0≤x≤ 0.45) single crystals are investigated. The anomalies in the temperature dependences of these quantities are identified
with diverse magnetic and structural phase transformations, including antiferromagnetic and ferromagnetic ordering, structural
transitions between strongly distorted (Jahn-Teller) and weakly distorted (pseudocubic) orthorhombic phases, structural transitions
to a rhombohedral phase and unusual transitions to a polaron-ordering state. As a result, the complete T-x phase diagram of the system La1−2x
Sr
x
MnO3 is constructed in a wide interval of temperatures T=4.2∓1050 K and concentrations x=0−0.45.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 331–336 (25 August 1998) 相似文献
45.
46.
In homogeneous negative phase velocity media, the Doppler and Cherenkov-Vavilov effects and the refraction and pressure of light are anomalous: they are inverse with respect to the corresponding effects in conventional media. Using the geometrical optics approximation, it is shown that the optical Magnus effect in inhomogeneous negative phase velocity media is also anomalous. The effect is demonstrated by considering a metamaterial consisting of parallel amorphous ferromagnetic microwires in a magnetic field. The metamaterial proves to be a left-handed one in the realistic region of the electromagnetic spectrum. The optical properties of such a left-handed medium can be controlled by the external magnetic field. 相似文献
47.
48.
Experimental results from HERA on diffractive vector meson production and their theoretical interpretation within microscopic
QCD are reviewed with an emphasis on the BFKL color dipole and k
T
-factorization approaches.
The text was submitted by the authors in English. 相似文献
49.
A theory of a low-pressure discharge in a xenon-molecular hydrogen mixture is developed. It is shown that, in such a discharge, at an interelectrode distance of L = 1 cm and a total plasma pressure of p 0 ~ 1 Torr, the density of negative hydrogen ions produced via the dissociative attachment of thermal electrons to vibrationally excited molecules H2 can reach a value as high as NH ? ≥ 1012 cm?3. According to calculations, the electron temperature in discharge operating regimes under study attains T e ≈ 1?2 eV, which corresponds to the maximum of the e-v exchange rate constant of H2 molecules. This ensures a relatively high rate of vibrational pumping of H2 molecules in the discharge. 相似文献
50.
Standardization and certification in the area of environmentally degradable plastics 总被引:1,自引:0,他引:1
Andrej Krzan Sarunya Hemjinda Stanislav Miertus Emo Chiellini 《Polymer Degradation and Stability》2006,91(12):2819-2833
Environmentally degradable polymers and plastics (EDPs) are a group of polymeric materials experiencing a rapid growth in number as well as in their applications and quantities used. The assessment of their key characteristic - degradability, including eventually biodegradability as the ultimate stage, is scientifically and technically a challenging issue and has led to differing interpretations in the past. In order to standardize techniques and criteria a number of standards were established by different standardization bodies which are also used as a basis for certification schemes. An up-to-date inventory of the rapidly growing standardization body is presented with basic interpretation to help guide the non-expert. A basic introduction to EDPs and polymer degradation is added for clarity. 相似文献