Spatial distribution of lamin A/C determines nuclear stiffness and stress-mediated deformation

While diverse cellular components have been identified as mechanotransduction elements, the deformation of the nucleus itself is a critical mechanosensory mechanism, implying that nuclear stiffness is essential in determining responses to intracellular and extracellular stresses. Though the nuclear membrane protein lamin A/C is known to contribute to nuclear stiffness, bulk moduli of nuclei have not been reported for various levels of lamin A/C. Here we measure the nuclear bulk moduli as a function of lamin A/C expression and applied osmotic stress, revealing a linear dependence within the range of 2-4 MegaPascal (MPa). We also find that the nuclear compression is anisotropic, with the vertical axis of the nucleus being more compliant than the minor and major axes in the substrate plane. We then related the spatial distribution of lamin A/C with sub-micron 3D nuclear envelope deformation, revealing that local areas of the nuclear envelope with higher density of lamin A/C have correspondingly lower local deformations. These findings describe the complex dispersion of nuclear deformations as a function of lamin A/C expression and distribution, implicating a lamin A/C role in mechanotransduction.

Investigation of surface morphology of thin metal films with magnetic layers Fe-Cr-Co

Films containing layers of dispersion-hardening alloys (LDHA) based on the Fe-Cr-Co system were obtained by magnetron sputtering. LDHA acquire the properties of film permanent magnets after a single-stage «fast» high-vacuum annealing. Bulk materials acquire such properties only after many hours of multi-stage heat treatment. The film samples acquire these properties in tens of seconds. The morphology of their surface was studied to determine the origin of the coercive force of film samples. The surface morphology was studied using high resolution scanning electron microscopy and atomic force microscopy. We studied two compositions that, in bulk, have a different tendency to form many phases during crystallization. In magnetron sputtering, the alloy in which a multiphase state is easily formed is polycrystalline. The antipode alloy in magnetron sputtering is realized in an amorphous state. After annealing, both alloys are in a polycrystalline state. Electron microscopic examination showed that as a result of annealing, crystallites are formed with a large projection onto the substrate plane, which grow due to the nearest neighbors. Moreover, these crystallites have not only a large area, but also a height. After annealing, both alloys are in a polycrystalline state. Electron microscopic examination showed that as a result of annealing, crystallites are formed with a large projection onto the substrate plane, which grow due to the nearest neighbors. Moreover, these crystallites have not only a large area, but also a height. What is determined by atomic force microscopy. High crystallites are also faceted. This may indicate that the composition of these crystallites differs from the composition of the surrounding layer, which may be the reason for the increase in coercive force as a result of annealing.

Отрицательное магнитосопротивление в структуре n-InSb/ЖИГ

It is shown that for the n-InSb/YIG/GGG (YIG - yttrium iron garnet, GGG - gallium-gadolinium garnet) structure in the tangent to the substrate plane geometry of magnetization (H <10 kOe) at a temperature T≈300 K the magnetoresistance of about 1% is negative, while for n-InSb/GGG structure, in the same magnetization geometry, the magnetoresistance is positive (an increase in electrical resistance in a magnetic field). The negative magnetoresistance effect in the InSb/YIG/GGG structure is due to the influence of the YIG magnetization on the conduction electrons of InSb (proximity effect) and the magnitude of the effect is determined by the value of YIG magnetization and parameters of InSb films.

Temperatural conductivity of diluted water solutions graphen and nanostructures of graphen nanoparticles

The purpose of this work was to study the specific thermal conductivity of aqueous graphene dispersions and the diluted aqueous solution of nanostructures based on graphene and Au nanoparticles, as well as to determine the temperature and concentration dependences of the specific thermal conductivity of these aqueous dispersions. The objects of study were aqueous dispersions of graphene and nanostructures based on graphene and Au nanoparticles. Graphene has characteristic dimensions of the order of 150 - 200 nm in the plane. The Au nanoparticles also have an average size of about 50 nm and a star-like shape. In dry nanocomposites, graphene is oriented parallel to the substrate plane, and nanostars are evenly distributed on the sample surface. The specific volumetric thermal conductivity values of aqueous graphene dispersions and aqueous solutions of graphene-based nanoparticles and Au nanoparticles were obtained in the temperature range from 30оC to 60оC. A slight increase in the specific thermal conductivity was found with increasing temperature. The absolute values a/v of aqueous graphene dispersions are 1.6 times higher than in three-component systems. The concentration dependences of the thermal conductivity of the two systems studied are linear. It is determined that the values of the specific thermal conductivity of dry graphene nanofillers are 1,62 times higher than the thermal conductivity of a mixture of graphene and Au nanoparticles.

Кинетика роста планарных нитевидных нанокристаллов

A kinetic equation is obtained which describes the elongation rate of planar semiconductor nanowires growing via the vapor-liquid-solid mechanism in the substrate plane. Theoretical analysis of different regimes depending on the nanowire radius and epitaxial conditions shows that planar growth of nanowires can be limited by either the Gibbs-Thomson effect in a catalyst droplet (for small droplet size) or surface diffusion of adatoms (for larger nanowire radii. Diffusion-like dependence of the growth rate on the nanowire radius R has the form R^(-m), where the power exponent equal 1, 3/2 or 2 depending on the mechanism of surface diffusion transport.

Структура и свойства пленок оксида галлия, полученных высокочастотным магнетронным напылением

The properties of gallium-oxide films produced by the radio-frequency magnetron-assisted sputtering of a β-Ga_2O_3 target with deposition onto sapphire substrates are studied. The as-deposited gallium-oxide films are polycrystalline and contain crystallites of the α and β phases. Exposure to oxygen plasma does not bring about the appearance of new crystallites but makes crystallites several times larger in average dimensions in the substrate plane. After annealing at 900°C, the crystallite size becomes twice as large as that in the unannealed film. The films not subjected to thermal annealing exhibit a high resistance at 20°C. In the range of 50–500°C, the conductivity of the samples ( G ) only slightly depends on temperature ( T ) and, as T is elevated further, exponentially increases with the activation energy 0.7–1.0 eV. After annealing of the films in argon at 900°C (30 min), the conductivity G starts to sharply increase at T ≈ 350°C. In the dependence of ln G on T ^–1, a maximum in the range of 470–520°C and a portion of decreasing conductivity at higher temperatures are observed. The unusual temperature dependence of the conductivity after annealing is attributed to a change in the structure and phase composition of polycrystalline gallium-oxide films and, possibly, to some effects at the surface. The structures produced on insulating substrates are solar blind in the visible wavelength region and sensitive to radiation in the ultraviolet region (222 nm).

Структурные и электрические характеристики двухслойных тонких пленок Bi-=SUB=-4-=/SUB=-Ti-=SUB=-3-=/SUB=-O-=SUB=-12-=/SUB=-/(Ba,Sr)TiO-=SUB=-3-=/SUB=-, осажденных на кремниевую подложку методом высокочастотного распыления при повышенных давлениях кислорода

The 400–450-nm-thick Bi_4Ti_3O_12 thin films with various orientations of crystallites with respect to a normal to the (100)Si substrate plane have been studied. It is established that the crystallite orientation can be controlled by varying the composition of the 4-nm-thick Ba_ x Sr_1 – _ x TiO_3 sublayer. The use of Ba_0.4Sr_0.6TiO_3 as a sublayer leads to the growth of the Bi_4Ti_3O_12 film in the single-crystal state with plane (001) parallel to the substrate plane and with a monoclinic distortion of the crystal structure. The Ba_0.8Sr_0.2TiO_3 sublayer is shown to lead to the formation of four crystallite orientations: (111), (117), (100), and (110) and two groups of domains in the Bi_4Ti_3O_12 film; the first group with the polarization direction p-erpendicularly to the substrate and the second group with the polarization directed in the angular range 45.2°–57° with respect to a normal to the substrate. It is shown that, in the Bi_4Ti_3O_12 film with the Ba_0.8Sr_0.2TiO_3 sublayer, the polarization is directed to the substrate and is switched to new stable state with the polarization direction from the substrate when applying an external voltage higher than a critical one (4 V).

Структура и динамика решетки двухслойных гетероструктур титаната бария-стронция и слоистого титаната висмута разной толщины на подложке окcида магния

The results of the structure and lattice dynamics study of Bi4Ti3O12 films with a thickness varying from 4 to 430 nm on a (001) MgO substrate with a preliminarily deposited Ba0.4Sr0.6TiO3 (4 nm) sublayer are presented. Two-layer structures were fabricated by high-frequency sputtering of ceramic targets of the appropriate composition. X-ray diffraction studies at room temperature showed that in such heterostructures the c axis of the Bi4Ti3O12 film is perpendicular to the substrate plane, and the [100] axis makes an angle of ± 45◦ with the [100] MgO axis. Up to ≈ 40 nm of Bi4Ti3O12 film thickness, the unit cell have a compression strain in the normal to the substrate plane direction and tensile strain in the interface plane, for large thicknesses the sign of the deformation changes. The frequency shifts of phonon modes in the Bi4Ti3O12 film and the appearance of additional peaks in the Raman spectra were observed. It is indicating on increasement of monoclinic distortion of the films crystal structure compared to the bulk crystal.