Use of microlenses to improve the optical microscopy resolution and enhance Raman scattering DOI: 10.22184/1993-8578.2021.14.6.382.388
When interacting with light the microspheres form a narrow beam called a photonic nanojet. The use of this effect allows of implementing a super high-resolution microscopy to exceed the diffraction limit and the Raman scattering signal amplification. To enhance the extremely weak RS-signal, it is necessary to use the multiplicative surfaces. Here we demonstrate the photonic nanojet effects used for RS-signal enhancement in combination with giant Raman scattering produced by the active substrates, silver nanowires, nanoparticles and barium titanate microspheres.
Production of anisotropic magnetic powders of the neodymium – iron – boron system with high magnetic properties at an enlarged pilot plant DOI: 10.22184/1993-8578.2021.14.6.374.380
The study was carried out on highly coercive anisotropic powders of the Nd-Fe-B alloy system, which were prepared by HDDR process. The HDDR process has been proven to be possible under optimum conditions in a large volume of magnetic powder to be processed. Experimental batch of Nd-Fe-B powder was produced and the magnetic characteristics of the powder were determined.
Nanoporous silicate matrices: optical homogeneity problems DOI: 10.22184/1993-8578.2021.14.6.364.37
The paper discusses issues related to the methodology for assessing the optical quality of nanoporous silicate matrices. The results of the study of samples at various stages of their production using the method of digital holographic interferometry are presented. The gravity effect on the formation of a porous structure in the process of chemical etching was analysed.
Shell-based analysis of magnetic resonance diffusion tensor imaging. Part I DOI: 10.22184/1993-8578.2021.14.6.328.333
Even with substantial sensitivity at high magnetic field, it is still challenging to investigate small-scale structures, such as brain cortex. A recent study has shown that very high resolution diffusion imaging is possible allowing investigation the cortical depth dependence of diffusion properties over the whole human brain in vivo. The results revealed that the main diffusion tensor orientation in the cortex is perpendicular to the cortical surface. At the same time the main diffusion direction is mostly tangential at banks and radial at the tips of the white matter – grey matter interface. Thus quantitative diffusion tensor measures can reveal structural organization of cells in the human cerebral cortex with the potential to characterize cortical cytoarchitecture in vivo and to investigate the pathophysiology of diseases associated with changes in cortical grey matter.
New look on the New look on the optical microscopy of bacteria through microlensmicroscopy of bacteria through microlens DOI: 10.22184/1993-8578.2021.14.6.336.340
Highly sensitive and selective measurements of bacteria cells in real-time mode remain a complicated task. Standard methods for identifying the organisms, such as antibody antigen tests, tests on C-reactive protein or procalcitonin are very sensitive, but still quite expensive yet. Readily available methods, for example, growing in agar, can provide the necessary sensitivity, selectivity and reliability, but usually require at least 24 hours for obtaining the results, which can be critical for some disease cases. Hence, in order to exclude the advent of new drug-resistant strains of bacteria, it is necessary to develop new simple and cheap methods for quickly detecting and studying bacteria.
Method for removal of silicon surface microdefects by laser ablation DOI: 10.22184/1993-8578.2021.14.6.342.349
One of the limiting factors for continuous yield improvement of micro-sized products at MEMS production lines is a non-zero average level of contamination of the production facilities. This factor impacts appearance of surface defects in the finished goods, which can disrupt the functionality of detectors. This paper proposes a method of post-processing of the manufactured sensitive elements by evaporating silicon defects without violating the integrity of the products in order to transfer the defective products to the category of good ones. Approbation of the proposed method at MEMS production of Mapper LLC showed that the effectiveness of removal of defects by the laser ablation is up to 77% for a batch. The performance indicator can be increased through further process automation.
Synthesis of Zn2SNO4 films deposited using spray pyrolysis technology and their application in NO2 gas sensors for a bronchial asthma diagnostic device DOI: 10.22184/1993-8578.2021.14.6.350.360
This paper describes the spray pyrolysis technology of deposition, from aqueous solutions of metal salts, polycrystalline film Zn2SnO4, with a grain size of 9 nm calculated by the Scherrer formula. The film is applied by spraying a mixture of metal salt solutions in the form of an aerosol onto a glass substrate heated to 420 °C. The optimal deposition mode was demonstrated and the composition of the resulting structure was monitored using X-ray diffraction analysis. The morphology of the film surface was studied by AFM. The electrical parameters of the film were measured by the Van der Pauw method and the Hall effect. The resistivity of the film, the type of conductivity, concentration and mobility of charge carriers were measured. The band gap was determined from the light absorption spectra. With the help of the obtained information on the composition and morphology in an analytical way, based on the literature and calculated data, it was concluded that this material can be used for a supersensitive NO2 express control sensor for a bronchial asthma diagnostic device.