Application of Graphene in Acoustoelectronics.

An interdigital transducer structure was fabricated from multilayer graphene on the surface of the YZ-cut of a LiNbO ferroelectric crystal. The multilayer graphene was prepared by CVD method and transferred onto the surface of the LiNbO substrate. The properties of the multilayer graphene film were studied by Raman spectroscopy.

Influence of Exposure to a Wet Atmosphere on the UV-Sensing Characteristics of ZnO Nanorod Arrays.

Zinc oxide is a promising material for the creation of various types of sensors, in particular UV detectors. In this work, arrays of ordered nanorods were grown by chemical vapor deposition. The effect of environmental humidity on the sensing properties of zinc oxide nanorod arrays was investigated, and a prototype UV sensor using indium as an ohmic contact was developed.

Antiplatelet Action of Chloramine Derivatives of Adenosine Phosphates and Their Chemical Activity in Relation to Sulfur-Containing Compounds.

We studied the properties of N6-chloroadenosine phosphates (ATP, ADP, and AMP chloramines) as compounds with potentially increased antiplatelet efficacy determined by their binding to the plasma membrane of platelets. Chloramine derivatives of ATP, ADP, and AMP do not differ in their optical absorption characteristics: their absorption spectra are in the range of 220-340 nm with a maximum at 264 nm. Chloramines of adenosine phosphates are characterized by high reactivity with respect to thiol compounds.

Coefficients of Thermal Expansion in LaGaSiO and CaTaGaSiO Crystals.

The ordered CaTaGaSiO and disordered LaGaSiO crystals of the lantangallium silicate family were grown via the Czochralski method. The independent coefficients of thermal expansion of crystals αc and αa were determined using X-ray powder diffraction based on the analysis of X-ray diffraction spectra measured in the temperature range of 25~1000 °C. It is shown that, in the temperature range of 25~800 °C, the thermal expansion coefficients are linear.

Changes in the Raman Spectrum of Monolayer Graphene under Compression/Stretching Strain in Graphene/Piezoelectric Crystal Structures.

Results from studying the effect of an applied electric voltage on the Raman spectrum of graphene deposited on a lithium niobate crystal substrate with a ferroelectric domain structure are presented. The use of the principal component method for data processing in combination with correlation analysis made it possible to reveal the contribution to the change in the spectra associated with the linear deformation of the substrate due to the inverse piezoelectric effect. An effect of the graphene coating peeling was found.

Acoustically Stimulated Charge Transport in Graphene Film.

The process of acoustically stimulated charge transport in the graphene film on the surface of the YZ-cut of a LiNbO crystal was investigated. It was found that the dependence of the current in the graphene film on the frequency of the surface acoustic wave (SAW) excitation repeats the amplitude-frequency response of the SAW delay time line. It is shown that increasing the SAW amplitude leads to an increase in the current in the graphene film, and the current in the graphene film depends linearly on the amplitude of the high-frequency input signal supplied to the interdigital transducer (IDT, in dB).

X-ray Diffuse Scattering from CaNbGaSiO Single Crystal under External Electric Field Application.

X-ray diffuse scattering from the CaNbGaSiO (CNGS) crystal was measured with a triple axis X-ray diffractometer under the conditions of an external electric field. It is found that the nature of the intensity distribution of the asymmetrical part of diffuse scattering depends on the value of the applied electric field. This phenomenon is apparently associated with different piezoelectric characteristics of defect regions and the rest of the single crystal.

Piezo-modulated active grating for selecting X-ray pulses separated by one nanosecond.

We present a novel method of temporal modulation of X-ray radiation for time resolved experiments. To control the intensity of the X-ray beam, the Bragg reflection of a piezoelectric crystal is modified using comb-shaped electrodes deposited on the crystal surface. Voltage applied to the electrodes induces a periodic deformation of the crystal that acts as a diffraction grating, splitting the original Bragg reflection into several satellites.

Engineering of Numerous Moiré Superlattices in Twisted Multilayer Graphene for Twistronics and Straintronics Applications.

Because of their unique atomic structure, 2 materials are able to create an up-to-date paradigm in fundamental science and technology on the way to engineering the band structure and electronic properties of materials on the nanoscale. One of the simplest methods along this path is the superposition of several 2 nanomaterials while simultaneously specifying the twist angle between adjacent layers (θ), which leads to the emergence of Moiré superlattices. The key challenge in 2 nanoelectronics is to obtain a nanomaterial with numerous Moiré superlattices in addition to a high carrier mobility in a stable and easy-to-fabricate material.

Ultraviolet Radiation Sensor Based on ZnO Nanorods/LaGaSiO Microbalance.

The possibility of creating resonant ultraviolet (UV) sensors based on the structure of ZnO nanorods/LaGaSiO microbalance (LCM) has been investigated. The principle of sensor operation is based on the desorption of oxygen from the surface of ZnO nanorods upon irradiation with UV light and an increase in the concentration of charge carriers that leads to an increase in the capacitance of the structure of ZnO nanorods/LCM. It has been shown that UV radiation intensity affects the resonance oscillation frequency of the LCM sensor.

The Peculiarities of the Acoustic Waves of Zero-Order Focusing in Lithium Niobate Plate.

In this research, beam focusing in lithium niobate plate was studied for fundamental anti-symmetric (A) and symmetric (S) Lamb waves, and the shear-horizontal (SH) wave of zero-order. Using the finite element method, appropriate configuration of the interdigital transducer with arc-like electrodes was modeled accounting for the anisotropy of the slowness curves and dispersion of the modes in the plate. Profiles of the focalized acoustic beams generated by the proposed transducer were theoretically analyzed.

Single crystals of ferroelectric lithium niobate-tantalate LiNbTaO solid solutions for high-temperature sensor and actuator applications.

Ferroelectric LiNbTaO solid solutions with various Nb/Ta ratio were grown from the melt by the Czochralski method. The exact composition of the grown crystals was determined by inductively coupled plasma atomic mass spectrometry. The dependence of the crystal composition on the composition of the initial melt was obtained and explained by a wide separation between the phase boundaries of the liquid and solid phases on the LiNbO-LiTaO phase diagram.

Pulse picker for synchrotron radiation driven by a surface acoustic wave: erratum.

An erratum is presented to correct the typographical errors concerning the composition of the multilayer used in the experiment in Opt. Lett. 42, 1915.

Influence of the Quantum Well Structure and Growth Temperature on a Five-Layer InGaMnAs Quantum Well with an InGaAs Buffer Layer.

The influence of quantum well structure and growth temperature on a synthesized multilayer system composed of a five-layer InMnGaAs quantum well with an InGaAs buffer layer grown on semi-insulating (100)-oriented substrates prepared by low temperature molecular beam epitaxy was studied. The magnetization measurements using a superconducting quantum interference device indicated the existence of ferromagnetism with a Curie temperature above room temperature in the five-layer InGaMnAs quantum well structure with an InGaAs buffer layer in a GaAs matrix. X-ray diffraction and secondary ion mass spectroscopy measurements confirmed the second phase formation of ferromagnetic GaMn clusters.

Study of middle infrared difference frequency generation using a femtosecond laser source in LGT.

We demonstrate phase-matched difference frequency generation in the emerging nonlinear crystal LaGaTaO. Tunable wavelengths between 1.4 and 4.

Pulse picker for synchrotron radiation driven by a surface acoustic wave.

A functional test for a pulse picker for synchrotron radiation was performed at Diamond Light Source. The purpose of a pulse picker is to select which pulse from the synchrotron hybrid-mode bunch pattern reaches the experiment. In the present work, the Bragg reflection on a Si/BC multilayer was modified using surface acoustic wave (SAW) trains.

Observation of sagittal X-ray diffraction by surface acoustic waves in Bragg geometry.

X-ray Bragg diffraction in sagittal geometry on a Y-cut langasite crystal (LaGaSiO) modulated by Λ = 3 µm Rayleigh surface acoustic waves was studied at the BESSY II synchrotron radiation facility. Owing to the crystal lattice modulation by the surface acoustic wave diffraction, satellites appear. Their intensity and angular separation depend on the amplitude and wavelength of the ultrasonic superlattice.

[Molecular characteristics and prediction of the reactive properties of the N-chlorotaurine analogs].

A number of molecular characteristics for the N-chlorotaurine structural analogs, amino acid chloramines and relative compounds have been computed by the ab initio method B3LYP/6-31G. In particular, the characteristics were the Mulliken atomic charges for the chloramine part and its adjacent atoms. A quantitative measure of the capabilities of the chloramines to react with the methionine sulfide group or sulfhydryl group of reduced glutathione was their reaction rate constants.

Phase-matching directions, refined Sellmeier equations, and second-order nonlinear coefficient of the infrared Langatate crystal La₃Ga(5.5)Ta(0.5)O₁₄.

We directly measured phase-matching directions of second harmonic, sum, and difference frequency generations in the Langatate La₃Ga(5.5)Ta(0.5)O₁₄ (LGT) uniaxial crystal.

Inhibition of plasma coagulation and platelet aggregation with structural analogs of taurine chloramine.

We studied the effects of amide and N-alkyl analogs of taurine chloramine on rabbit plasma coagulation and platelet aggregation. Alkyl analog N-isopropyl-N-chlorotaurine produced greater increase in plasma coagulation time after its activation by the contact method or with thrombin than amide analog N-propionyl-N-chlorotaurine. In case of coagulation induced by the tissue factor, the test analogs produced similar effect.

[Covalent chloramine inhibitors of blood platelet functions: computational indices for their reactivity and antiplatelet activity].

The quantum mechanics computation of the reactivities of chloramine derivatives of amino acids and taurine has been accomplished. A pair of computational indices that reflect a predisposition of alpha amino acid chloramines to chemical decay have been revealed. One of the indices was the dihedral angle for the chain of four atoms: carbons at beta- and alpha-positions, carbon of the carboxyl group, and carbonyl oxygen.

X-ray beam induced current method at the laboratory x-ray source.

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image.

[The relatioship between decomposition of amino acid chloramines and their structures].

Rate constants of the decomposition of monoamine alpha-amino acid chloramine derivatives were determined by a spectrophotometeric method. Several amino acid chloramines with elevated stability have been found. These included n-chloroglycine, n-chlorovaline, n-chlorothreonine, and n-chloroisoleucine.

[Amino acid chloramines and chlorimines as antiplatelet agents: reactive properties and mechanism of action].

Oxidative modifications of thiols, disulfide, and thioester atomic groups in proteins, peptides, and amino acids induced by chloramines or chloramine derivatives of amino acids and other reactive oxidants are considered. In the case of disulfide and thiol groups, production of sulfur-reactive groups may take place, such as disulphide S-oxides and sulphenic groups. Various chloramines and chloramines differently modify sulfur-containing groups.

Antiaggregant effect of taurine chloramines in the presence of serum albumin.

The effects of taurine chloramine derivatives on initial aggregation of isolated platelets suspended in buffered saline were studied. Inhibition of ADP-induced aggregation in pure cell suspension depended on the structure of chloramine antiaggregants. The most effective of them was N,N-dichlorotaurine; its concentration needed for 50% inhibition of aggregation was about 0.