Crystalline Elements Research Articles

Simulations of dislocation contrast in dark-field X-ray microscopy.

Dark-field X-ray microscopy (DFXM) is a full-field imaging technique that non-destructively maps the structure and local strain inside deeply embedded crystalline elements in three dimensions. In DFXM, an objective lens is placed along the diffracted beam to generate a magnified projection image of the local diffracted volume. This work explores contrast methods and optimizes the DFXM setup specifically for the case of mapping dislocations. Forward projections of detector images are generated using two complementary simulation tools based on geometrical optics and wavefront propagation, respectively. Weak and strong beam contrast and the mapping of strain components are studied. The feasibility of observing dislocations in a wall is elucidated as a function of the distance between neighbouring dislocations and the spatial resolution. Dislocation studies should be feasible with energy band widths of 10-2, of relevance for fourth-generation synchrotron and X-ray free-electron laser sources.

On Computation and Analysis of Entropy Measures for Metal-Insulator Transition Super Lattice

Mathematical chemistry plays a vital role in investigating the metal-insulator transition Superlattice (GST-SL) of strongly correlated 3 D electrons due to quantum confinement. The development of epitaxial GST-SL thin films with the design of heterogenous openings is of extraordinary interest due to their applications. The thin-film declaration and the construction of exceptionally arranged amalgam accumulates are crucial for phase transformation application in non-erratic retentiveness. Softening and crystalline elements of the multi-part GST composite have been explored. This paper determines some topological properties, such as degree-based topological descriptors and their entropy measures. More precisely, we analyzed the entropy and the heat of the formation of single crystals, monolayers, and various layers of Ge–Sb–Te.

Possibilities of multislice computed tomography in assessing the structural and compositional features of calcium-containing urinary stones

The aim: to study the X-ray density index (HU) in calcium-containing urinary stones with different structural and compositional features. The structural and compositional features of 118 samples of calcium-containing urinary stones, which were obtained as a result of extracorporeal shock wave lithotripsy, percutaneous nephrolithotripsy and ureteroscopic lithotripsy in patients with kidney and ureteral stones were studied. The structural features of the stones were evaluated by conducting a crystal-optical analysis, during which the linear dimensions, shape, color and degree of transparency of crystalline elements were estimated, and the volume fractions of the amorphous and crystalline phases in the sample structure were calculated. The compositional features of kidney stones were studied on the basis of a qualitative and quantitative assessment of their mineral composition by infrared spectroscopy. X-ray density of calcium-containing kidney stones was assessed based on the data of computed tomography without contrast, which was performed in all patients in the preoperative period. Structural and compositional features of calcium-containing urinary stones are characterized by the presence in their composition of calcium oxalate compounds in the form of vewellite and weddelite, as well as calcium phosphate in the form of apatite, hydroxylapatite, fluorapatite, carbonate apatite, which, depending on the stage of crystallization, can be in amorphous, amorphous-crystalline or crystalline state. The X-ray density of this type of urinary stones, according to multislice computed tomography, corresponds to the range of 1090-1785 HU. There is a direct correlation between the level of X-ray density of the stone and the volume fraction of the crystalline phase in its structure.

EPIDEMIOLOGICAL STUDY OF RISK FACTORS OF RENAL STONES FORMATION AMONG PATIENTS ATTENDING IN BLOCK PHC-THANJAVUR DISTRICT Authors

Introduction: Urolithiasis is the third most common and painful disease in the globe, afflicting both men and women. The accumulation of a few minerals and crystalline elements in the renal calculi and urinary bladder are during the process of metabolism. The study's goals were to determine the frequency of risk variables for urinary stone patients. Methods: Across-sectional study had on urinary stone disease in Thanjavur and the surrounding areas. The study included 102 cases, 79 urinary stone patients, and 23 normal patients that all lived in the same area. Results: A total of 102 participants between the ages of 20 - 70 were studied. Thirty-eight percentages of urinary stone patients were over 60 years old. In this study, men accounted for 63 %. It was discovered that kidney stone patients were more prevalent in the age groups 41-70 (77%) and <40 (23%), which was statistically significant (15.5±20.51; p=0.01). Patients with lower education levels (56%) and patients from lower-income areas were found. The non-veg food intake status showed a higher proportion of kidney stone patients with control (68% vs. 13%), which was statistically significant (36.06±28.5; p = 0.005). Conclusion: This study confirms that the urinary stone formation may be due to the various environmental factors. The significant associated with the risk factors between control and urinary stone patients were found. The high burdens of urinary stone formation were observed and their associations of socio-demographic behavioral risk factor and the results have been discussed.

Study of the reliability of quartz resonators in miniature ceramic packages

Objectives. In the development of radio electronics and communications, it is important that the requirements for the reliability, stability of the generated frequencies, and selectivity of the receiving equipment are fulfilled. The use of quartz resonators, widely used in radio circuits today, has partially allowed for the reliability of communication devices and guaranteed high frequency stability to be enhanced without complicating the circuit. Modern global trends in the development of electrical equipment are associated with miniaturization. The dimensions of quartz resonators are decreasing every year, while the requirements for reliability remain high. The study aimed to evaluate the possibility of using quartz resonators packaged in a miniature ceramic case 2.5 × 2.0 × 0.6 mm, under conditions of elevated ambient temperature. It has also allowed for the development of optimal requirements for the thermal training regime as the basic technological operation for stabilizing the oscillation frequency.Methods. Reliability testing of quartz resonators and methods of statistical modeling in radio engineering.Results. The results established the requirements for the reliability of RK588 quartz resonators in miniature ceramic cases 2.5 × 2.0 × 0.6 mm in size under the influence of elevated ambient temperatures of +85 °C and +125 °C. The requirements for frequency drift when exposed to elevated ambient temperature on the crystalline plate type based on RF patent No. 27122426 “Method of manufacturing thin crystalline plates and thin crystalline elements” were also specified. The method of thermal training was optimized and the ageing coefficients were established.Conclusions. The coefficients of ageing calculated for the resonators during the reliability tests was as follows: Batch No. 1 at a temperature of +85 °C was 0.75; and for Batch No. 2 at a temperature of +125 °C was 0.18. For this type of piezoelectric element with a size of 1.5 × 1.0 mm at an operating temperature of +125 °C the ageing coefficient is 4 times lower than at a temperature of +85 °C. This indicates the possibility of using the RK588 resonator at elevated ambient temperatures.

X-ray free-electron laser based dark-field X-ray microscopy: a simulation-based study

Dark-field X-ray microscopy (DFXM) is a nondestructive full-field imaging technique providing three-dimensional mapping of microstructure and local strain fields in deeply embedded crystalline elements. This is achieved by placing an objective lens in the diffracted beam, giving a magnified projection image. So far, the method has been applied with a time resolution of milliseconds to hours. In this work, the feasibility of DFXM at the picosecond time scale using an X-ray free-electron laser source and a pump–probe scheme is considered. Thermomechanical strain-wave simulations are combined with geometrical optics and wavefront propagation optics to simulate DFXM images of phonon dynamics in a diamond single crystal. Using the specifications of the XCS instrument at the Linac Coherent Light Source as an example results in simulated DFXM images clearly showing the propagation of a strain wave.

Оценка кристаллогенной активности меда северных территорий Нижегородской области в различных разведениях

Crystallization of honey is one of its main properties. The component composition of honey has been studied for a very long time, but there are no express methods for examining its characteristics. For this reason, the issue of finding innovative methods for assessing the quality and safety of bee honey remains relevant at the present time. The aim of the study was to evaluate the effect of various honey dilutions on the crystallization of a model crystal-forming solution. Twenty samples of polyfler honey collected from apiaries located on the territory of the Shakhunya district of the Nizhny Novgorod region in the summer served as the material for the study. 4 samples were formed from each collected honey sample, the mass of each of which was 0.1 g, then homogenization of all samples was carried out. By adding an appropriate amount of saline solution to the honey samples, the following dilutions were obtained: 1:4, 1:8, 1:16, 1:32. A control sample representing 0.9% sodium chloride solution was also used. 100 μl of substrate from each sample was applied to a slide and dried in vivo. Facias were analyzed by microscopy using qualitative and quantitative criteria. It was found that in micro-preparations of diluted honey, the density of crystalline elements monotonically increases from the minimum dilution to the maximum. This is due to the high concentration of carbohydrates in honey, which are known inhibitors of crystallization. The use of this testing method during the examination will allow to identify the presence of honey adulterants with artificially increased sugar content.

Geometrical-optics formalism to model contrast in dark-field X-ray microscopy

Dark-field X-ray microscopy, DFXM, is a new full-field imaging technique that non-destructively maps the structure and local strain inside deeply embedded crystalline elements in three dimensions. In DFXM an objective lens is placed along the diffracted beam to generate a magnified projection image of the local diffracted volume. In this work, a general formalism based on geometrical optics is provided for the diffraction imaging, valid for any crystallographic space group. This allows the simulation of DFXM images based on micro-mechanical models. Example simulations are presented with the formalism, demonstrating how this may be used to design new experiments or to interpret existing ones. In particular, it is shown how modifications to the experimental design may tailor the reciprocal-space resolution function to map specific components of the deformation-gradient tensor. The formalism supports multi-length-scale experiments, as it enables DFXM to be interfaced with 3D X-ray diffraction. To illustrate the use of the formalism, DFXM images are simulated from different contrast mechanisms on the basis of the strain field around a straight dislocation.

Prolate and oblate chiral liquid crystal spheroids.

Liquid crystals are known to exhibit intriguing textures and color patterns, with applications in display and optical technologies. This work focuses on chiral materials and examines the palette of morphologies that arises when microdroplets are deformed into nonspherical shapes in a controllable manner. Specifically, geometrical confinement and mechanical strain are used to manipulate orientational order, phase transitions, and topological defects that arise in chiral liquid crystal droplets. Inspired by processes encountered in nature, where insects and animals often rely on strain and temperature to alter the optical appearance of dispersed liquid crystalline elements, chiral droplets are dispersed in polymer films and deformation induced by uniaxial or biaxial stretching. Our measurements are interpreted by resorting to simulations of the corresponding systems, thereby providing an in-depth understanding of the morphologies that arise in these materials. The reported structures and assemblies offer potential for applications in smart coatings, smart fabrics, and wearable sensors.

Spontaneous Resolution and Super-coiling in Xerogels of the Products of Photo-Induced Formose Reaction.

This work addresses the supramolecular self-organization in the xerogels of formose reaction products. The UV-induced formose reaction was held in over-saturated formaldehyde solutions at 70∘C without a catalyst. The solutions of the obtained carbohydrates were dried on a glass slide, and the obtained xerogels demonstrated a prominent optical activity, while the initial solutions were optically inactive. The xerogels contained highly elongated crystalline elements of a helical structure as well as the isometric ones. Thus xerogel formation was accompanied by a spontaneous resolution of enantiomers and separation of different-shaped supramolecular structures. The thick helices were twisted of thinner ones, while the latter were twisted of elementary structures having a diameter much smaller than 400 nm. Similar structural hierarchy is typical of biological macromolecules (DNA, proteins, and cellulose). Summarizing the obtained results, we proposed a hypothetical mechanism explaining the amplification of the initial enantiomeric excess, as well as chiral and chemical purification of the substances which were essential for the evolution of Life to start.

Возможности протонного магнитного резонанса в определении степени кристалличности целлюлозы

A layered model of the structural organization of macrofibrils of native cellulose, consisting of microfibrils, which include elementary fibrils, has been developed. A feature of the proposed model is the presence of slit-like pores between the crystalline elements of cellulose. It was found that, on average, each water molecule interacts with one glucose residue of the surface chains of cellulose with the formation of hydrogen bonds in the framework of monolayer adsorption. This allows to establish a correlation between the cellulose crystallinity and the capacity of the adsorption water monolayer on its active surface. Based on the condition of rapid molecular exchange between the adsorption water layers in the framework of the Bloembergen-Purcell-Pound theory, an approach is proposed for determination the capacity of water monolayer. The obtained values are consistent with the results of solving the Brunauer-Emmett-Teller equation for the adsorption isotherm of water on the active surface of cellulose. The Fourier transform of the free induction decay signal of cellulose allows to estimate its crystallinity at various moisture contents. Methods have been developed for assessing the crystallinity of different types of dry cellulose based on NMR relaxation parameters — spin-lattice relaxation time and spin-spin relaxation time. Using the method of deuteration of cellulose, the relaxation times of its crystalline regions were determined. The results of preliminary studies showed that the crystallinity of cotton cellulose is higher in comparison with the same parameter of woody types of cellulose. A comparison of the literature and the data we obtained using 1H-NMR relaxation confirmed the possibility of utilizing the developed methods to solve the tasks of scientific research and conducting quality control of cellulosic materials at specialized enterprises.

CRYSTALLOGENIC PROPERTIES OF THE BLOOD SERUM OF RATS UNDER MODELING A THERMAL INJURY

Aim. To study the crystallogenic and initiating potential of biological fluids in rats under normal conditions and when modeling a contact thermal injury. Material and methods. To this end, we used our own model of contact thermal burn. This experiment involved the impact of a hot plate on the back of the animal, with the lesion area amounting to 20% of the body surface (3rd degree burn). This model of thermal injury was reproduced in 30 Wistar rats. 24 hours after the burn experiment, the animals were subjected to blood tests. Subsequently, an evaluation of the blood crystallogenic and initiating properties was performed. The range of basic substances used in teziographic tests was rather conventional and included 0.45, 0.9 and 3% sodium chloride solutions, as well as 0.1 N hydrochloric acid and sodium hydroxide solutions. The results of own and initiated crystallization of biological fluids were evaluated using the authors’ system of semi-quantitative indicators. Results. It is found that, in comparison with intact animals, micro-preparations of dried blood serum from rats after thermal trauma demonstrate a significant inhibition of both own crystallization and that initiated by various basic substances. This phenomenon is manifested in a significant decrease in the index of structural facies (in a crystalloscopic test), the main teziographic coefficient and the belt coefficient. The pathological nature of the observed shifts in the crystallogenic properties of biological fluids emphasizes a sharp increase in the degree of destruction demonstrated by the crystalline elements of the blood samples of rats in the main group. Conclusion. The conducted research shows that a model thermal injury in rats is accompanied by significant shifts in the crystallostasis of an animal organism, which are manifested in a significant change in the crystallogenic and initiating properties of the blood serum.

Topological flexible metamaterials with isotropic dual-frequency terahertz-band absorption

This study demonstrates an isotropic flexible absorptive metamaterial structure for terahertz wave bands based on topological-optimization design. One rotationally symmetric absorbing element consists of a polarization-sensitive metamaterial cell arranged with a counterclockwise topology. A flexible topological metamaterial absorber is formed from crystalline elements through an infinite periodic arrangement using Floquet’s theorem. This artificial material achieves dual-frequency absorption with peak absorptions of 94% and 99.9% at 0.136 and 0.143 THz, respectively. The independent polarization angle of the two absorption peaks exceeds 45°under an oblique incident-wave process operation and in bending measurement, which indicate polarization isotropy. The equivalent electrical thickness corresponding to the minimum resonance point is close to one-ninth. The proposed ultra-thin flexible artificial material not only possesses perfect conformity with complex surfaces but also achieves larger angle electromagnetic absorption. The study results can present this material a potential candidate for polarized manipulation in electromagnetic stealth and electromagnetic control in the terahertz technology.

Reciprocal space mapping and strain scanning using X-ray diffraction microscopy

Dark-field X-ray microscopy is a new full-field imaging technique for nondestructively mapping the structure of deeply embedded crystalline elements in three dimensions. Placing an objective in the diffracted beam generates a magnified projection image of a local volume. By placing a detector in the back focal plane, high-resolution reciprocal space maps are generated for the local volume. Geometrical optics is used to provide analytical expressions for the resolution and range of the reciprocal space maps and the associated field of view in the sample plane. To understand the effects of coherence a comparison is made with wavefront simulations using the fractional Fourier transform. Reciprocal space mapping is demonstrated experimentally at an X-ray energy of 15.6 keV. The resolution function exhibits suppressed streaks and an FWHM resolution in all directions of ΔQ/Q = 4 × 10−5 or better. It is demonstrated by simulations that scanning a square aperture in the back focal plane enables strain mapping with no loss in resolution to be combined with a spatial resolution of 100 nm.

Numerical study of Bragg CDI on thick polycrystalline specimens.

Bragg coherent diffraction imaging (BCDI) is a powerful X-ray imaging technique for crystalline materials, providing high resolution maps of structure and strain. The technique is typically used to study a small isolated object, and is in general not compatible with a bulk polycrystalline sample, due to overlap of diffraction signals from various crystalline elements. In this paper, we present an imaging method for bulk samples, based on the use of a coherent source. The diffracted X-ray beam from a grain or domain of choice is magnified by an objective before being monitored by a 2D detector in the far field. The reconstruction principle is similar to the case of BCDI, while taking the magnification and pupil function into account. The concept is demonstrated using numerical simulations and reconstructions. We find that by using an object-lens distance shorter than the focal length, the numerical aperture is larger than in a traditional imaging geometry, and at the same time the setup is insensitive to small phase errors by lens imperfections. According to our simulations, we expect to be able to achieve a spatial resolution smaller than 20 nm when using the objective lens in this configuration.

Influence of thickness on crystallinity in wafer-scale GaTe nanolayers grown by molecular beam epitaxy

We grew wafer-scale, uniform nanolayers of gallium telluride (GaTe) on gallium arsenide (GaAs) substrates using molecular beam epitaxy. These films initially formed in a hexagonal close-packed structure (h-GaTe), but monoclinic (m-GaTe) crystalline elements began to form as the film thicknesses increased to more than approximately 90 nm. We confirmed the coexistence of these two crystalline forms using x-ray diffraction and Raman spectroscopy, and we attribute the thickness-dependent structural change to internal stress induced by lattice mismatch with the substrate and to natural lattice relaxation at the growth conditions.

Investigation of CaMoO4 single crystals with low residual absorption

Calcium molybdate enriched with the 100Mo isotope (40Ca100MoO4) is a promising material for use in cryogenic scintillation detectors. The main requirements of crystalline elements of the detector are absence of color and the attenuation coefficient (μ) not higher than 0.01cm−1 at 520nm wavelength. 40Ca100MoO4 and 40Ca100MoO4:Nb5+ single crystals have been investigated. The influence of isothermal annealing on the attenuation spectra in the 350 to 700nm wavelength range has been studied. A broad absorption band with a maximum at λ=460nm is observed in the attenuation spectra of the sample.The dichroism phenomenon which is associated with anisotropy of the color centers in the crystals is observed along directions perpendicular to the optical axis. Annealing of the enriched samples at 1250°C in an O2 atmosphere leads to a substantial reduction of the intensity of the band near 460nm.The attenuation coefficient of the 40Ca100MoO4:Nb5+ crystals meets the requirement, which is μ≪0.01cm−1 at λ=520nm. It is determined that absorption band near 460nm and dichroism are absent.

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Nanostructural haemocompatible coatings for the internal side of artificial blood vessels

The main goal of the work was to elaborate low thrombogenicity of surface inside tube-like elements for cardiovascular system support by combination of low-temperature glow discharge and hydrogel coatings to inhibit blood-clotting cascade activation. A large share of amorphous phase silicon was observed in the microstructure analysis. The crystalline elements were uniformly distributed in the amorphous structure. Combination of low thickness, the proper microstructure and density of the coatings provided a highly flexible nature of the whole system. The blood-material interaction was analyzed in vitro in dynamic conditions by using a designed and fabricated novel blood flow simulator. Coatings deposited by the glow discharge expressed good hemocopatibile properties. The use of hydrogel coatings did not reduce coagulation parameter. Hydrogel coatings did not improve the hemocompatibility of the surface modified with carbon based coatings. Modification of surface with hydrogel resulted in further increased risk of hemolysis.

Mechanical Properties of 7075 Aluminium Matrix Composites Reinforced by Nanometric Silicon Carbide Particulates

Aluminum Matrix composites (AMCs) are known as light weight and high-strength materials with their potential application in areas such as aerospace, automobile, defence, engineering and other industries. AMCs have the advantage to significantly reduce the overall weight of the vehicles and aircraft while maintaining their structural strength. Reinforcement of micron or nano-sized range particles with aluminium matrix yields improved mechanical and physical properties in composite materials. The strength of Al matrix composites will be improved about 20% with decreasing reinforcement particle size from micrometric scale to nanometric scale. In this study, Al7075 alloy and nano SiC composites have been fabricated by Electromagnetic stir casting process combined with mechanical stirring. Different weight % of nano SiC particles (0.5, 1, 1.5, and 2 wt%) were used for synthesis of composites. Certain test methods scanning electron microscopy (SEM) and X-Ray diffraction (XRD) are used to examine the microstructure along with the measurement of impact strength of the nano composite. SEM microstructure shows SiC particles are fairly infused into the matrix alloy with agglomeration and porosity at some places. X-Ray Diffraction (XRD) analysis acknowledged that no unknown crystalline elements are present in the composites while mixing reinforcement with Al alloy matrix. The results impact strength shows that impact strength decreases with respect to the base metal because of brittle nature of reinforcement.