19 research outputs found
Biofunctional nanomaterials based on ultra fine silica, protein and aminocarbohydrates
Aim. Investigation of adsorptive interactions of N-acetyl-D-glucosamine (GlcNAc) and N-acetylneuraminic acid (NANA) with ultra fine silica (UFS) modified by protein bovine serum albumin (BSA). Methods. Adsorption, IR-, 1H NMR- and laser Doppler spectroscopy. Results. Conditions for obtaining bionanocomposites (BNC) UFS/GlcNAc, UFS/BSA/GlcNAc and UFS/BSA/NANA are developed. Conclusions. Impellent ability of deconservated bovine gametes decreased in the presence of BNC after adsorptive fastening of protein on UFS surface. The 1H NMR spectroscopy data proved that interaction of GlcNAc with protein was accompanied by essential dehydratation of protein molecules.Цель. Исследование адсорбционных взаимодействий N-ацетил-D-глюкозамина (GlcNAc) и N-ацетилнейраминовой кислоты (N-АНК) с высокодисперсным кремнеземом (ВДК), модифицированным белком бычьим сывороточным альбумином (БСА). Методы. Адсорбция, ИК-, 1Н ЯМР- и лазерно-допплеровская спектроскопия. Результаты. Разработаны условия получения бионанокомпозитов (БНК) ВДК/GlcNAc; ВДК/БСА/GlcNAc и ВДК/БСА/N-АНК. Выводы. Двигательная способность деконсервированных гамет быка снижается в присутствии БНК после адсорбционного закрепления на его поверхности белка. На основе данных 1Н ЯМР-спектроскопии установлено, что взаимодействие GlcNAc с белком сопровождается сильной дегидратацией его молекул.Мета. Дослідження адсорбційних взаємодій N-ацетил-D-глюкозаміну (GlcNAc) та N-ацетилнейрамінової кислоти (N-АНК) з високодисперсним кремнеземом (ВДК), модифікованим білком бичачим сироватковим альбуміном (БСА). Методи. Адсорбція, ІЧ-, 1Н ЯМР- та лазерно-допплерівська спектроскопія. Результати. Розроблено умови отримання біонанокомпозитів (БНК): ВДК/GlcNAc; ВДК/БСА/GlcNAc та ВДК/БСА/N- АНК. Висновки. Здатність до руху деконсервованих гамет бика знижується за присутності БНК після адсорбційного закріплення на його поверхні білка. На основі даних 1Н ЯМР- спектроскопії встановлено, що взаємодія GlcNAc з білком супроводжується сильною дегідратацією його молекул
Critical Dynamics of Magnets
We review our current understanding of the critical dynamics of magnets above
and below the transition temperature with focus on the effects due to the
dipole--dipole interaction present in all real magnets. Significant progress in
our understanding of real ferromagnets in the vicinity of the critical point
has been made in the last decade through improved experimental techniques and
theoretical advances in taking into account realistic spin-spin interactions.
We start our review with a discussion of the theoretical results for the
critical dynamics based on recent renormalization group, mode coupling and spin
wave theories. A detailed comparison is made of the theory with experimental
results obtained by different measuring techniques, such as neutron scattering,
hyperfine interaction, muon--spin--resonance, electron--spin--resonance, and
magnetic relaxation, in various materials. Furthermore we discuss the effects
of dipolar interaction on the critical dynamics of three--dimensional isotropic
antiferromagnets and uniaxial ferromagnets. Special attention is also paid to a
discussion of the consequences of dipolar anisotropies on the existence of
magnetic order and the spin--wave spectrum in two--dimensional ferromagnets and
antiferromagnets. We close our review with a formulation of critical dynamics
in terms of nonlinear Langevin equations.Comment: Review article (154 pages, figures included
Weak antiferromagnetism due to Dzyaloshinskii-Moriya interaction in BaCuOCl
The antiferromagnetic insulating cuprate BaCuOCl contains
folded CuO chains with four magnetic copper ions () per unit cell.
An underlying multiorbital Hubbard model is formulated and the superexchange
theory is developed to derive an effective spin Hamiltonian for this cuprate.
The resulting spin Hamiltonian involves a Dzyaloshinskii-Moriya term and a more
weak symmetric anisotropic exchange term besides the isotropic exchange
interaction. The corresponding Dzyaloshinskii-Moriya vectors of each magnetic
Cu-Cu bond in the chain reveal a well defined spatial order. Both, the
superexchange theory and the complementary group theoretical consideration,
lead to the same conclusion on the character of this order. The analysis of the
ground-state magnetic properties of the derived model leads to the prediction
of an additional noncollinear modulation of the antiferromagnetic structure.
This weak antiferromagnetism is restricted to one of the Cu sublattices.Comment: 13 pages, 1 table, 4 figure
Magnetic Field Effects on Neutron Diffraction in the Antiferromagnetic Phase of
We discuss possible magnetic structures in UPt based on our analysis of
elastic neutron-scattering experiments in high magnetic fields at temperatures
. The existing experimental data can be explained by a single-{\bf q}
antiferromagnetic structure with three independent domains. For modest in-plane
spin-orbit interactions, the Zeeman coupling between the antiferromagnetic
order parameter and the magnetic field induces a rotation of the magnetic
moments, but not an adjustment of the propagation vector of the magnetic order.
A triple-{\bf q} magnetic structure is also consistent with neutron
experiments, but in general leads to a non-uniform magnetization in the
crystal. New experiments could decide between these structures.Comment: 5 figures included in the tex