Synthesis and Application of Domestic Glassy Carbon TiO2 Nanocomposite for Electrocatalytic Triclosan Detection

Nanoparticles of TiO2 are suitable for many catalytic and photocatalytic applications due to their extraordinary properties such as superhydrophobicity, semiconductivity, electron-rich, and environmental compatibility. The main crystalline phases of TiO2, anatase, and rutile possess different crystal structures, crystallinity, crystalline sizes, and specific surface areas, and these characteristics directly affect the catalytic performance of TiO2. In the present study, domestic carbon material enhanced with TiO2 nanoparticles was synthesized and used for the construction of a modified carbon paste electrode. The electrocatalytic activity of the modified electrodes was investigated depending on the TiO2 crystalline phases in the electrode material. Furthermore, the obtained working electrode was utilized for triclosan detection. Under optimized experimental conditions, the developed electrode showed a submicromolar triclosan detection limit of 0.07 µM and a wide linear range of 0.1 to 15 µM. The relative standard deviations for repeatability and reproducibility were lower than 4.1%, and with satisfactory selectivity, the proposed system was successfully applied to triclosan monitoring in groundwater. All these results confirm that the sustainable production of new and domestically prepared materials is of great benefit in the field of electrocatalysis and that the morphology of such produced materials is strongly related to their catalytic properties

Optical fine needle biopsy in hepatocellular carcinoma mouse model

The paper describes the results of experimental studies using custom developed optical biopsy system for diagnostics in vivo during the procedure of fine needle aspiration biopsy. Experimental studies were conducted in laboratory mice with inoculated hepatocellular carcinoma. The measurements were carried out using fluorescence spectroscopy and diffuse reflectance spectroscopy methods to reveal metabolic and morphological changes in tissues. The results show that the developed approach is sensitive for cancer detection. Quantified differences in the maximum of fluorescence spectra and diffuse reflectance spectra between tumor and normal tissues were demonstrated and approved with morphological analysis

Investigation of blood microcirculation parameters in patients with rheumatic diseases by videocapillaroscopy and laser Doppler flowmetry during cold pressor test

Videocapillaroscopy (VCS) and laser Doppler flowmetry (LDF) are non-invasive methods for evaluating microcirculation parameters. The VCS method is based on a high-speed video recording of capillaries in the nailfold. The recorded video frames are processed using a specialized algorithm to determine the red blood cells velocity. The LDF technique is based on the analysis of the Doppler shift of back-scattered laser radiation from moving red blood cells. In this work, simultaneous measurements of VCS and LDF have been performed in healthy volunteers and rheumatic patient. The study was conducted using a cold pressor test. Changes were recorded in response to cold exposure in rheumatic diseases

Magnetic and structural properties of barium hexaferrite BaFe12O19 from various growth techniques

Barium hexaferrite powder samples with grains in the m-range were obtained from solid-state sintering, and crystals with sizes up to 5 mm grown from PbO, Na2CO3, and BaB2O4 fluxes, respectively. Carbonate and borate fluxes provide the largest and structurally best crystals at significantly lower growth temperatures of 1533 K compared to flux-free synthesis (1623 K). The maximum synthesis temperature can be further reduced by the application of PbO-containing fluxes (down to 1223 K upon use of 80 at % PbO), however, Pb-substituted crystals Ba1-xPbxFe12O19 with Pb contents in the range of 0.23(2) x 0.80(2) form, depending on growth temperature and flux PbO content. The degree of Pb-substitution has only a minor influence on unit cell and magnetic parameters, although the values for Curie temperature, saturation magnetization, as well as the coercivity of these samples are significantly reduced in comparison with those from samples obtained from the other fluxes. Due to the lowest level of impurities, the samples from carbonate flux show superior quality compared to materials obtained using other methods

Brain metabolism changes in cases of impaired breathing or blood circulation in rodents evaluated by real time optical spectroscopy methods

The aim of the study was to compare the metabolic activity of brain cortex after the acute hypoxia caused by the impairment of breathing or blood circulation. Male Wistar rats were randomized in two groups: impaired breathing and blood circulation failure groups. Fluorescence under 365 and 450 nm excitation and diffuse reflectance intensity at 550-820 nm range were estimated. We found that after long-term hypoxic conditions, notable metabolic changes occur. We suppose that oxygen deficiency causes an activation of the GABA shunt mechanism. In cases of blood circulation failure, fluorescence intensity changes faster than in cases of breathing impairment

Friction Stir Welding of a TRIP Fe49Mn30Cr10Co10C1 High Entropy Alloy

The effect of friction stir welding parameters on the structure and properties of Fe49Mn30Cr10Co10C1 high-entropy alloy welds was studied. Due to the development of the TRIP effect, the mechanical behaviour of this alloy was associated with the γ fcc-to-ε hcp martensitic transformation. In the initial condition, the microstructure of the program alloy comprised equiaxed fcc grains and small fractions of the hcp ε-martensite (~5%) and M23C6 carbides (~4%). Friction stir welding of the program alloy resulted in recrystallization of the stir zone and a decrease in the fraction of the carbides to 1–2%; however, the percentage of the hcp phase remained at nearly the same level as that in the initial condition. Post-welding tests showed a considerable increase in the strength and microhardness of the welds both due to the recrystallization-induced decrease in grain size and martensitic transformation

Hybrid Self-Reinforced Composite Materials Based on Ultra-High Molecular Weight Polyethylene

The properties of hybrid self-reinforced composite (SRC) materials based on ultra-high molecular weight polyethylene (UHMWPE) were studied. The hybrid materials consist of two parts: an isotropic UHMWPE layer and unidirectional SRC based on UHMWPE fibers. Hot compaction as an approach to obtaining composites allowed melting only the surface of each UHMWPE fiber. Thus, after cooling, the molten UHMWPE formed an SRC matrix and bound an isotropic UHMWPE layer and the SRC. The single-lap shear test, flexural test, and differential scanning calorimetry (DSC) analysis were carried out to determine the influence of hot compaction parameters on the properties of the SRC and the adhesion between the layers. The shear strength increased with increasing hot compaction temperature while the preserved fibers’ volume decreased, which was proved by the DSC analysis and a reduction in the flexural modulus of the SRC. The increase in hot compaction pressure resulted in a decrease in shear strength caused by lower remelting of the fibers’ surface. It was shown that the hot compaction approach allows combining UHMWPE products with different molecular, supramolecular, and structural features. Moreover, the adhesion and mechanical properties of the composites can be varied by the parameters of hot compaction

GROWTH DEVICE, CRYSTAL GROWTH AND CHARACTERIZATION OF ALEXANDRITE

Alexandrite is beryllium aluminate Al2O3•BeO doped with minor levels of chromophores, Cr2O3 being the major one. The engineering application of single crystals of synthetic alexandrite is currently limited to active elements of tunable IR-lasers for remote sensing and medicine. In the design of the mechanical components of any crystal-growth systems, especially high-temperature systems, there are two basic requirements: long-term stability of the dimensions of the heating equipment; and uniform rotary and translational motion of the crystal over a wide speed range. Accordingly, it is assumed for the heating system that the heater and internal screens are made of tungsten and the heater is cylindrical. In the present work, authors describe a new high-temperature furnace for a crystal-growth system, with new designs of the heater, screens, copper leads, and the lid. To eliminate the sealed input, which is the primary source of non-uniform crystal motion, the kinematic system, including the motor, is placed in a volume connected to the furnace

Nanoporous Layers and the Peculiarities of Their Local Formation on a Silicon Wafer

This review presents the results of the local formation of nanostructured porous silicon (NPSi) on the surface of silicon wafers by anodic etching using a durite intermediate ring. The morphological and crystallographic features of NPSi structures formed on n- and p-type silicon with low and relatively high resistivity have also been investigated. The proposed scheme allows one to experiment with biological objects (for example, stem cells, neurons, and other objects) in a locally formed porous structure located in close proximity to the electronic periphery of sensor devices on a silicon wafer