2,152 research outputs found
Thermal Conductance for Single Wall Carbon Nanotubes
We report a theoretical analysis of the phonon thermal conductance, \kappa
(T), for single wall carbon nanotubes (SWCN). In a range of low temperatues up
to 100K, \kappa (T) of perfect SWCN is found to increase with temperature,
approximately, in a parabolic fashion. This is qualitatively consistent with
recent experimental measurements where the tube-tube interactions are
negligibly weak. When the carbon-carbon bond length is slightly varied, \kappa
(T) is found to be qualitatively unaltered which implies that the anharmonic
effect does not change the qualitative behavior of \kappa (T).Comment: Revtex, 4 figure
Multiple Superconducting Gaps, Anisotropic Spin Fluctuations and Spin-Orbit Coupling in Iron-Pnictides
This article reviews the NMR and NQR studies on iron-based high-temperature
superconductors by the IOP/Okayama group. It was found that the electron pairs
in the superconducting state are in the spin-singlet state with multiple
fully-opened energy gaps. The antiferromagnetic spin fluctuations in the normal
state are found to be closely correlated with the superconductivity. Also the
antiferromagnetic spin fluctuations are anisotropic in the spin space, which is
different from the case in copper oxide superconductors. This anisotropy
originates from the spin-orbit coupling and is an important reflection of the
multiple-bands nature of this new class of superconductors.Comment: 20 pages, 16 figure
Screening for the optimal siRNA targeting a novel gene (HA117) and construction and evaluation of a derivative recombinant adenovirus
We found a novel gene named as HA117 in our previous research. At this study, we screened for an optimal siRNA targeting the novel gene HA117 using the pSOS-HUS method, verified the results of pSOS-HUS siRNA screening for optimal affinity for the target gene, and constructed and evaluated a recombinant adenovirus carrying the DNA template for transcription of the optimal HA117 siRNA. The pSOS-HUS vector method was successfully utilized as a rapid and effective screen for an optimal siRNA for a target gene. Among five pairs of DNA templates, siRNA transcribed from HAi5 gave the strongest interference with the novel gene HA117; a HAi5-carrying recombinant adenovirus (Ad-HAi5) was successfully constructed and evaluated, laying a foundation for the further study of HA117 gene function with RNAi technology
Superconductivity of the Ternary Boride Li_2Pd_3B Probed by ^{11}B NMR
We report a ^{11}B NMR measurement on the recently discovered superconductor
Li_2Pd_3B. The nuclear spin lattice relaxation rate 1/T_1 shows a well-defined
coherence peak just below T_c (H=1.46 T)=5.7 K, and the spin susceptibility
measured by the Knight shift also decreases below T_c. These results indicate
that the superconductivity is of conventional nature, with an isotropic gap.
Our results also suggest that the -electrons of boron and the d-electrons of
palladium that hybridize with boron -electrons are primarily responsible for
the superconductivity.Comment: 4 pages, 5 figure
Field-Induced Ferromagnetic Order and Colossal Magnetoresistance in La_{1.2}Sr_{1.8}Mn_2O_7: a ^{139}La NMR study
In order to gain insights into the origin of colossal magneto-resistance
(CMR) in manganese oxides, we performed a ^{139}La NMR study in the
double-layered compound La_{1.2}Sr_{1.8}Mn_2O_7. We find that above the Curie
temperature T_C=126 K, applying a magnetic field induces a long-range
ferromagnetic order that persists up to T=330 K. The critical field at which
the induced magnetic moment is saturated coincides with the field at which the
CMR effect reaches to a maximum. Our results therefore indicate that the CMR
observed above T_C in this compound is due to the field-induced ferromagnetism
that produces a metallic state via the double exchange interaction
Luttinger-volume violating Fermi liquid in the pseudogap phase of the cuprate superconductors
Based on the NMR measurements on BiSrLaCuO
(La-Bi2201) in strong magnetic fields, we identify the non-superconducting
pseudogap phase in the cuprates as a Luttinger-volume violating Fermi liquid
(LvvFL). This state is a zero temperature quantum liquid that does not break
translational symmetry, and yet, the Fermi surface encloses a volume smaller
than the large one given by the Luttinger theorem. The particle number enclosed
by the small Fermi surface in the LvvFL equals the doping level , not the
total electron number . Both the phase string theory and the dopon
theory are introduced to describe the LvvFL. For the dopon theory, we can
obtain a semi-quantitative agreement with the NMR experiments.Comment: The final version in PR
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