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81.
Pawel Lukaszczuk E. Borowiak-Palen Mark H. Rümmeli Ryszard J. Kalenczuk 《Applied Physics A: Materials Science & Processing》2010,100(2):505-510
In this contribution we present a systematic study on the dispersion of SWCNTs in a water-based solution of biocompatible
detergent: sodium deoxycholate (DOC). By avoiding harsh chemical conditions, which are known to damage nanotubes structure,
a stable SWCNTs suspension was created. Long term stirring of the solution led to preparation of a stable transparent solution,
containing well-dispersed isolated SWCNTs. The as-prepared dispersion remained stable and clear for two months. Optical absorption
spectroscopy was employed to measure SWCNTs suspension stability. Nanotube aggregation was evaluated through the tangential
mode (G mode) present in the Raman spectrum. High-resolution transmission electron microscopy was employed to observe the
mechanism of debundling process. 相似文献
82.
Jerzy Grzybowski Hubert Przybycień Ryszard Urbański 《Set-Valued and Variational Analysis》2013,21(2):201-216
Any abstract convex cone S with a uniformity satisfying the law of cancellation can be embedded in a topological vector space $\widetilde{S}$ (Urbański, Bull Acad Pol Sci, Sér Sci Math Astron Phys 24:709–715, 1976). We introduce a notion of a cone symmetry and decompose in Theorem 2.12 a quotient vector space $\widetilde{S}$ into a topological direct sum of its symmetric subspace $\widetilde{S}_s$ and asymmetric subspace $\widetilde{S}_a$ . In Theorem 2.19 we prove a similar decomposition for a normed space $\widetilde{S}$ . In section 3 we apply decomposition to Minkowski–Rådström–Hörmander (MRH) space with three best known norms and four symmetries. In section 4 we obtain a continuous selection from a MRH space over ?2 to the family of pairs of nonempty compact convex subsets of ?2. 相似文献
83.
We report on extensive experimental investigations of a single crystal of the orthorhombic uranium compound UCoGe. Bulk measurements on as-grown and annealed single crystals, recording magnetization, magnetic susceptibility, electrical resistivity, magnetoresistivity, thermopower, thermal conductivity and heat capacity data do not reproduce the previously reported coexistence of ferromagnetism with superconductivity. The latter phenomenon was only observed for the annealed sample at T SC = 0.65 K. New observations show a crossover at around 13 K, visible in thermal and transport measurements as well as the coherent state around 50 K, signaled by a wide knee in ρ(T). Above this temperature, UCoGe exhibits a single-ion Kondo-like effect. The magnetoresistivity of the annealed single crystal increases negatively down to 4.2 K, reaching as a large value about ?27% at a field of 8 T. The latter may be interpreted in terms of fairly strong magnetic fluctuations existing in UCoGe at low temperatures. 相似文献
84.
The thermal conductivity (κ) of single crystals of tetragonal uniaxial antiferromagnets USb2 (T N = 202 K) and UBi2 (T N = 180.8 K) has been measured along the a-axis (κa ) over the temperature range from 0.5 to 300 K and along the c-axis (κc ) from 0.5 to 70 K. The as-grown samples have residual resistivity ratio (RRR) values of about 500–600 and 100–150 for UBi2 and USb2, respectively. The anisotropy of the thermal conductivity (κa (T)/κc (T) ~ 5) and the low-T Lorenz ratios are discussed in relation to Fermi surface topology for both compounds. 相似文献
85.
Czechowski T Krzyminiewski R Jurga J Chlewicki W 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,195(1):52-59
New EPR resonators were developed by using a ceramic material with a high dielectric constant, epsilon=160. The resonators have a high quality factor, Q=10(3), and enhance the sensitivity of an EPR spectrometer up to 170 times. Some advantages of the new ceramic resonators are: (1) cheaper synthesis and simplified fabricating technology; (2) wider temperature range; and (3) ease of use. The ceramic material is produced with a titanate of complex oxides of rare-earth and alkaline metals, and has a perovskite type structure. The resonators were tested with X-band EPR spectrometers with cylindrical (TE(011)) and rectangular (TE(102)) cavities at 300 and 77K. We discovered that EPR signal strength enhancement depends on the dielectric constant of the material, resonator geometry and the size of the sample. Also, an unusual resonant mode was found in the dielectric resonator-metallic cavity structure. In this mode, the directions of microwave magnetic fields of the coupled resonators are opposite and the resonant frequency of the structure is higher than the frequency of empty metallic cavity. 相似文献
86.
We report on the fabrication of two-dimensional polymeric photonic crystal membranes on the surface of silicon using visible-light multibeam interference lithography. The structures are created by the interference of three beams of a green laser. A polymer buffer layer doped with a Rhodamine B laser dye, interlaid between the lithography layer and the silicon substrate, suppresses the effects of strong reflection and nonradiative absorption of silicon on the interference pattern. Large-area defect-free photonic crystal membranes are experimentally realized on silicon surface. 相似文献
87.
We prove that the correlations present in a multipartite quantum state have an operational quantum character even if the state is unentangled, as long as it does not simply encode a multipartite classical probability distribution. Said quantumness is revealed by the new task of local broadcasting, i.e., of locally sharing preestablished correlations, which is feasible if and only if correlations are stricly classical. Our operational approach leads to natural definitions of measures for quantumness of correlations. It also reproduces the standard no-broadcasting theorem as a special case. 相似文献
88.
Ryszard Smarzewski 《Proceedings of the American Mathematical Society》1997,125(5):1391-1397
We give a new characterization of the set of all extreme points of the unit ball in the Banach space of all Lipschitz functions on a metric space This result is applied to get a total variation characterization of in the particular case when is a convex subset of a Banach space.
89.
90.
Bierla K Dernovics M Vacchina V Szpunar J Bertin G Lobinski R 《Analytical and bioanalytical chemistry》2008,390(7):1789-1798
A method was developed for the simultaneous determination of selenomethionine (SeMet) and selenocysteine (SeCys) in meat (chicken
and lamb muscles) and different offal tissues (heart, liver, kidney). The analytical procedure was based on the protein extraction
with urea under reducing conditions (dithiothreitol), derivatization of SeCys and SeMet by carbamidomethylation with iodoacetamide
(IAM) followed by quantitative proteolysis. The mixture of the derivatized Se-amino acids was purified by size-exclusion liquid
chromatography (LC) and analysed by ion-paring reversed-phase HPLC–inductively coupled plasma mass spectroscopy (ICP MS).
The quantification of SeCys and SeMet was carried out by the method of standard additions. 77SeMet was used to control the SeMet derivatization efficiency and recovery. The method was validated by the determination
of the Se mass balance. The Se-amino acids accounted for 91 ± 8% of the total selenium (mean of 95 samples of seven tissues
analysed over a period of 18 months). The method was applied to the discrimination of the contribution of selenoproteins (containing
SeCys) and other Se-containing proteins (containing SeMet) in tissues of animals during supplementation studies (dose–effect
and tolerance). 相似文献