The analysis of unsteady MHD flow over a porous stretching plate is critical for various engineering applications, particularly in systems involving chemical reactions and thermal radiation. This study explores the novel effects of heat and mass transfer in a two-dimensional unsteady magnetohydrodynamic (MHD) flow. This present work examines the effects of radiation and a transverse magnetic field on a chemically reacting fluid flowing over a stretched plate. The unsteady nature of the flow is associated with the time-dependent variations in stretching/extending velocity, temperature, and fluid concentration. The nonlinear governing boundary layer partial differential equations (PDEs) are transformed into a set of nonlinear ordinary differential equations (ODEs) using a similarity transformation, which are then numerically solved using the MATLAB bvp4c method. The flow, heat, and concentration profiles are quantitatively analysed through graphs for various problem parameters, including the unsteadiness parameter (A), Hartmann number (M), porosity parameter (Sp), radiation parameter (N), chemical reaction parameter (K), Soret number (Sr), Eckert number (Ec), Schmidt number (Sc), and Prandtl number (Pr). Additionally, the skin friction coefficient, Nusselt number (Nu), and Sherwood number (Sh) are numerically addressed and illustrated using graphs.

Out-of-furnace treatment of steel has many possibilities for correcting the iron-carbon semi-product obtained at the previous stage of steel production. This is ensured both by various methods of maintaining the temperature and by introducing the necessary correcting or modifying additives into the ladle with subsequent averaging stirring of the melt. At the same time, the bottom type of purging through one or more purging units became the most widespread. The paper presents the results of research on the nature of the flows created during bottom purging through a block with non-directional porosity. The research was conducted with the help of a full-scale physical model using water as a model fluid and using the conductometric method of establishing the homogeneity of the liquid bath and dissolution additives of the “heavy” type (using NaCl salt for modelling). Those additives dissolve mostly at the bottom and, for their volume distribution, require the creation of sufficient mixing flows. The study was carried out at different intensities of gas supply for purging according to the purging modes corresponding to industrial conditions. It was established that during purging in the bubbling mode through a block with non-directional porosity, the largest change in concentration during purging occurs in the volume of the liquid bath at the level of more than 25% from the bottom of the ladle. A large change in concentration indicates a significant volume of dissolution of “heavy” additives that dissolve at the bottom. This can be explained by the formation of conditions for the spiral rotation of the grouped bubble flow that breaks into individual bubbles at a distance of approx. 75% from the bottom of the ladle. Such flows create active horizontal mixing of the liquid bath. The best conditions for mixing the liquid bath, under conditions of addition of “heavy” additives that dissolve at the bottom, with the shortest homogenization time among the studied conditions were purging with an intensity of gas supply of 0.684-1.026 m3/t steel per h.

To reduce emissions in the mobility sector, demand for high-strength and higher-strength steels in the automotive sector is constantly increasing, and with it the demands on the tools of the sheet metal processing industry. One important phenomenon is rapid wear which reduces the service life of blanking tools. Compensating with an increased use of lubricants is not advisable from an ecological point of view. It could be shown in literature that through texturing the lateral surfaces of blanking tools their wear behavior can be improved. In this work, machine hammer peening (MHP) was used to texture the surfaces. Compared to other deterministic texturing methods such as laser texturing, MHP has several beneficial effects. No additional surface finish is required after texturing and the surface structure is not weakened by the thermal influence. MHP machining simultaneously induces residual compressive stresses close to the surface, work-hardens the edge zone and smoothes roughness peaks. Combined with deterministic texturing in the same process step, the tribological behavior of the tool surface can be significantly improved. Based on the tribological investigations of the authors in the strip drawing test on different structuring strategies, the findings from the model test are to be transferred to the real test in this work. For this purpose, rotationally symmetrical blanking punches were textured using a specially developed texturing center. The machine hammer peening center allows surface texturing with positioning accuracies of less than 2% by controlling a rotary and feed axis in combination with frequency control of the machine hammer peening set up. A hammer head with micro-milled micro-tip was used as the texturing tool for the MHP. Different degrees of coverage with the same aspect ratio were applied to the surface. These punches were then tested on various materials on an industrial high-speed stamping press. To evaluate the effectiveness, the force curves for different blanking frequencies were analyzed and the evolution of the textured topography was continuously evaluated. The experiments reveal that the withdraw force could be reduced by 38% due to the micro texturing with a coverage of 18%. Other coverages led to an increase. By texturing the lateral surfaces of blanking punches using MHP the service life could also be significantly improved.

A cost-effective and straightforward hydrothermal approach was utilized to fabricate fluorescent nitrogen-modified carbon quantum dots (N-CQDs) from shrimp powder. The N-CQDs produced possessed a mean diameter of 5 nm and demonstrated intense emission at 420 nm when optimally excited at 350 nm. Additionally, N-CQDs displayed robust blue luminescence when exposed to UV light (λ= 365 nm). Their potential as fluorescence probes for detecting Fe3+ was investigated further. Compared to other metallic ions, N-CQDs demonstrated exceptional selectivity and sensitivity towards Fe3+. Moreover, N-CQDs exhibited stable and concentration-dependent fluorescent intensities with Fe3+ concentrations spanning between 10 to 140 µM, with a minimum detectable concentration of 1.42 μM.

The paper presents the results of an investigation into the reduction processes of iron ore titanomagnetite pellets using synthesis gas. The thermodynamic modelling was carried out using the TERRA software package. Synthesis gas is a mixture of carbon monoxide (CO) and hydrogen (H2), as well as other gases such as CO2 and N2. It is primarily used in the production of liquid fuels and chemical products, and is produced through the initial conversion of natural gas and coal fuel. The TERRA software package was used to model and predict chemical and phase transformations in pellets during reduction. The model takes into account the influence of temperature, hydrogen concentration, and other parameters on the reduction kinetics. Calculations were carried out with different gas mixtures and conditions to evaluate the model's effectiveness. The thermodynamic model constructed corresponds to the literature and calculated data and can be used to optimize the reduction process under various production conditions.

The application of microfluidic technology within the field of additive manufacturing is investigated, with a specific focus on devices designed for precise material dosing. An in-depth examination is conducted to explore how microfluidic technology can be integrated into Cartesian 3D printing systems, enabling precise and controlled material dispensing throughout the manufacturing process. A novel methodology was developed to assess these devices, evaluating their feasibility and effectiveness in improving the quality and efficiency of manufactured products. Experimental analysis was performed to examine various microfluidic device configurations and their impacts on material dosing precision, along with their potential for reducing waste. Promising advancements in additive manufacturing were demonstrated by the findings, which offer new insights and opportunities in fields such as medicine, electronics, and engineering. The foundation for enhancing material dosing control in additive manufacturing was laid by this study. Keywords: Microfluidic technology, additive manufacturing, precise material dosing, Synthetic material.

This research synthesized a composite ceramic material base CaCO3/Al2O3, CERMET, with possible biomedical applications. Eggshell was used as raw material to obtain CaCO3, and it was reinforced with silver nanoparticles to improve the structural and mechanical properties of the ceramic system. The addition of silver nanoparticles promotes the formation of two phases. The first is a continuous phase called a matrix formed of CaAl2O4 (calcium aluminate). The second is a dispersed phase known as reinforcement made up of silver nanoparticles. The composite ceramics were synthesized using the solid-state synthesis technique from a chemical mixture of CaCO3 and Al2O3 powders in the following chemical ratio: 49.5% CaCO3 + 50.5% Al2O3, with silver nanoparticles added at different percentages (1%, 5%, 10%, 15%). The powder mixture was made in a high-energy mill for homogenization. After that, the mixture was compressed into cylindrical samples for their consolidation by sintering in a high-temperature muffle with a controlled atmosphere, using heating ramps. The sintered samples were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy, and microhardness, including fracture toughness studies. In addition, the Archimedes method determined the sintered samples' density. The results showed a clear relation between the mechanical properties of the CaAl2O4 ceramic base and the incorporated silver nanoparticles since these increased as the percentage of silver nanoparticles increased. In addition, it was observed that the porosity of the samples could be controlled, making the composite material suitable for biomedical applications.

Photosensitizers have an important role in increasing the ability to capture light. One of the main components of dye-sensitized solar cells (DSSCs) is dye. In general, DSSC fabrication uses synthetic dyes such as N719 and DN-F01. However, synthetic dyes have the potential to have negative impacts on human health and the environment. In this research, DSSC fabrication was carried out using natural dyes and synthetic dyes at large sizes (one cell with an active area of 18 cm2 and two cells with an active area of 15 cm2). The natural dyes used are anthocyanin from red dragon fruit (dragon fruit dyes) and curcumin from turmeric powder (turmeric dyes). Natural and synthetic dyes were characterized using UV-Vis and FTIR spectroscopy. Meanwhile, DSSC performance was characterized by the I-V meter. The best electrical performance for natural dyes was obtained with an active area of 15 cm2 which was sensitized using turmeric dyes with a performance of Eff = 0.020%, Jsc = 0.142 mA.cm-2, Voc = 0.372 V, and FF = 0.461. Furthermore, the best electrical performance for synthetic dyes was obtained with an active area of 15 cm2 which was sensitized using N719 with a performance of Eff = 0.264%, Jsc = 1.303 mA.cm-2, Voc = 0.510 V, and FF = 0.398. Based on these results, natural dyes are less effective than synthetic dyes, but natural dyes are more environmentally friendly and cheap.

The object of the research is the series average of the dangerous parameters of the gas environment during the ignition of materials. The practical importance consists of using the difference between the average dangerous parameters of the gas environment on the intervals of absence and the presence of ignition to detect the ignition of materials. The theoretical substantiation of the method of detecting fires in premises is carried out based on sample averages fixed samples of current measurements of an arbitrary, dangerous parameter of the gas environment, which correspond to the general population of reliable absence and presence of fire. At a given significance level, the method determines the unbiased, uniformly most powerful fire detection rule. This allows you to determine how significant differences in sample means with a given significance level are due to ignition or are random. Laboratory experiments were conducted to verify the method of detecting the ignition of test materials. It was established, for example, that the maximum size of the effect ignition on the carbon monoxide concentration is typical for alcohol (exceeds the threshold by 8.9 times) and textiles (exceeds the threshold by 9.3 times). The size of the effect of the smoke density upon ignition of all materials is approximately the same and is determined by exceeding the corresponding thresholds from 4.62 to 3.9 times. The size of the effect on the temperature of the gaseous environment during ignition of all test materials is approximately the same order. It is characterized by exceeding the corresponding thresholds from 5.95 to 3.58 times. It is shown that the method of detecting fires allows to establish the extent to which the detected differences in sample means for samples from the general population of hazardous parameters of the gas environment are reliable with a given level of significance and are due to the ignition of materials or the action of random factors.

Self-activated multicolor phosphors are being used in more and more emerging fields. In order to explore the energy transfer between [NbO6]7- coordination groups and Sm3+ ions, a series of Ba3-ySmyTa1-xNbxGa3Si2O14 samples co-doped with Nb5+ and Sm3+ were prepared in this work, and the changes of luminous intensity under the condition of fixed Nb5+ concentration regulating Sm3+ concentration and fixed Sm3+ concentration regulating Nb5+ concentration were obtained respectively. By further fitting the emission decay curves of Sm3+ under two conditions, the decreasing average lifetime is obtained. Thermal stability tests of the samples also hinted the presence of such energy transfer. This regular change can provide a good reference for developing new self-activated phosphors.