611 research outputs found
Transition state method and Wannier functions
We propose a computational scheme for materials where standard Local Density
Approximation (LDA) fails to produce a satisfactory description of excitation
energies. The method uses Slater's "transition state" approximation and Wannier
functions basis set. We define a correction to LDA functional in such a way
that its variation produces one-electron energies for Wannier functions equal
to the energies obtained in "transition state" constrained LDA calculations. In
the result eigenvalues of the proposed functional could be interpreted as
excitation energies of the system under consideration. The method was applied
to MgO, Si, NiO and BaBiO and gave an improved agreement with experimental
data of energy gap values comparing with LDA.Comment: 13 pages, 6 figures, 1 tabl
Polarized neutron channeling as a tool for the investigations of weakly magnetic thin films
We present and apply a new method to measure directly weak magnetization in
thin films. The polarization of a neutron beam channeling through a thin film
structure is measured after exiting the structure edge as a microbeam. We have
applied the method to a tri-layer thin film structure acting as a planar
waveguide for polarized neutrons. The middle guiding layer is a rare earth
based ferrimagnetic material TbCo5 with a low magnetization of about 20 mT. We
demonstrate that the channeling method is more sensitive than the specular
neutron reflection method
Spin state of negative charge-transfer material SrCoO3
We employ the combination of the density functional and the dynamical
mean-field theory (LDA+DMFT) to investigate the electronic structure and
magnetic properties of SrCoO3, monocrystal of which were prepared recently. Our
calculations lead to a ferromagnetic metal in agreement with experiment. We
find that, contrary to some suggestions, the local moment in SrCoO3 does not
arise from intermediate spin state, but is a result of coherent superposition
of many different atomic states. We discuss how attribution of magnetic
response to different atomic states in solids with local moments can be
quantified.Comment: 5 pages, 5 figure
EFFECT OF IMMUNOTHERAPY ACTIVATED T-LYMPHOCYTES ON CELLULAR IMMUNITY IN DIFFERENT FORMS OF ATOPIC DERMATITIS
The article describes the results of therapy with autologous activated. T-lymphocytes in patients with atopic dermatitis. Has been shown high clinical efficacy and safety of this therapy in the treatment of patients with both allergic and nonallergic form of the disease. In the allergic form observed more rapid positive changes, but in the opposite form of the efficiency was higher. Influence on cellular immunity in different forms differed. If the allergic form there was an increase of CD8+ T-cells in the nonallergic form — increased CD8+CD25+ T-cells and changes in delayed-type hypersensitivity
Hard-wall Potential Function for Transport Properties of Alkali Metals Vapor
This study demonstrates that the transport properties of alkali metals are
determined principally by the repulsive wall of the pair interaction potential
function. The (hard-wall) Lennard-Jones(15-6) effective pair potential function
is used to calculate transport collision integrals. Accordingly, reduced
collision integrals of K, Rb, and Cs metal vapors are obtained from
Chapman-Enskog solution of the Boltzman equation. The law of corresponding
states based on the experimental-transport reduced collision integral is used
to verify the validity of a LJ(15-6) hybrid potential in describing the
transport properties. LJ(8.5-4) potential function and a simple thermodynamic
argument with the input PVT data of liquid metals provide the required
molecular potential parameters. Values of the predicted viscosity of monatomic
alkali metals vapor are in agreement with typical experimental data with the
average absolute deviation 2.97% for K in the range 700-1500 K, 1.69% for Rb,
and 1.75% for Cs in the range 700-2000 K. In the same way, the values of
predicted thermal conductivity are in agreement with experiment within 2.78%,
3.25%, and 3.63% for K, Rb, and Cs, respectively. The LJ(15-6) hybrid potential
with a hard-wall repulsion character conclusively predicts best transport
properties of the three alkali metals vapor.Comment: 21 pages, 5 figures, 41 reference
Unusual Excimer/Dimer Behavior of a Highly Soluble C,N Platinum(II) Complex with a Spiro-Fluorene Motif.
In this work, we introduce a spiro-fluorene unit into a phenylpyridine (CN)-type ligand as a simple way to deplanarize the structure and increase the solubility of the final platinum(II)···complex. Using a spiro-fluorene unit, orthogonal to the main coordination plane of the complex, reduces intermolecular interactions, leading to increased solubility but without significantly affecting the ability of the complex to form Pt···Pt dimers and excimers. This approach is highly important in the design of platinum(II) complexes, which often suffer from low solubility due to their mainly planar structure, and offers an alternative to the use of bulky alkyl groups. The nonplanar structure is also beneficial for vacuum-deposition techniques as it lowers the sublimation temperature. Importantly, there are no sp hybridized carbon atoms in the cyclometalating ligand that contain hydrogens, the undesired feature that is associated with the low stability of the materials in OLEDs. The complex displays high solubility in toluene, ∼10 mg mL , at room temperature, which allows producing solution-processed OLEDs in a wide range of doping concentrations, 5-100%, and EQE up to 5.9%, with a maximum luminance of 7400 cd m . Concurrently, we have also produced vacuum-deposited OLEDs, which display luminance up to 32 500 cd m and a maximum EQE of 11.8%
- …