Search

Purpose: The paper investigated the effect of selected processing conditions during gear grinding on the value and distribution of microhardness and residual stress formed in the technological surface layer of gears after thermochemical treatment (TCT) conducted by a continuous single-piece flow method. Design/methodology/approach: The gears were carburised with LPC at 920°C, then quenched in a 4D Quenching chamber at 7 bar and tempered at 190°C for 3 hours. In the next step, the working surfaces of the gear teeth were ground by supplying grinding fluid (GF) to the grinding zone using the WET method and the MQL method with a minimum amount. Measurements were made on the distribution of microhardness and residual stress formed in the technological surface layer of gears after thermochemical treatment and after the grinding process. Findings: The results of the study showed the influence of workpiece speed vw and the method of delivery to the grinding zone GF on selected parameters describing the condition of the technological surface layer of the teeth of gears made of 20MnCr5 steel. The grinding process with a white aluminium oxide grinding wheel causes deterioration in the material's residual stress state. For each of the three analysed workpiece speeds vw, smaller changes in microhardness with respect to the microhardness of the material before grinding occur in the surface layer of samples ground with GF fed with the MQL method. Similarly, residual stress values are in the area of favourable compressive stresses. Research limitations/implications: Environmental considerations and the need to comply with increasingly stringent environmental protection and worker safety regulations are pushing researchers and entrepreneurs to completely eliminate or reduce the consumption of grinding fluids in the grinding process. Based on the research and analysis carried out in this study, it was concluded that applying minimum GF by the MQL method could be an alternative to the conventional WET method. Practical implications: In sustainable manufacturing, it is extremely important to produce high-quality items while reducing the cost of manufacturing and taking care of the environment and workers' health. This includes the manufacture of gears, a basic component used in gear transmissions in the automotive industry, for example. The research has established that it is possible to use the MQL method, which reduces the amount of GF used when grinding the working surfaces of gear teeth, as an alternative to the conventional WET method. Originality/value: The conducted research was the first to determine the most favourable conditions, in terms of the obtained residual stresses and microhardness, for grinding the working surface of gear teeth using the MQL method. [ABSTRACT FROM AUTHOR]

Polyphenols are natural compounds found in many plants and their products. Their high structural diversity bestows upon them a range of anti-inflammatory, anti-oxidant, proapoptotic, anti-angiogenic, and anti-metastatic properties, and a growing body of research indicates that a polyphenol-rich diet can inhibit cancer development in humans. Polyphenolic compounds may modulate the expression, secretion, or activity of compounds that play a significant role in carcinogenesis, including type IV collagenases, such as matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9), by suppressing cellular signaling pathways such as nuclear factor-kappa B. These enzymes are responsible for the degradation of the extracellular matrix, thus promoting the progression of cancer. This review discusses the current state of knowledge concerning the anti-cancer activity of polyphenols, particularly curcumin, resveratrol, epigallocatechin-3-gallate, genistein, and quercetin, with a specific focus on their anti-invasive and anti-metastatic potential, based on the most recent in vitro and in vivo studies. It appears that polyphenols may be valuable options for the chemoprevention and treatment of cancer via the inhibition of MMP-2 and MMP-9 and the suppression of signaling pathways regulating their expression and activity.

Background: The dysregulation of extraocular muscles (EOMs) in the strabismus may be partly due to modification in the mitochondrial DNA (mtDNA). Currently, little is known about changes occurring in mtDNA of EOMs in patients with strabismus, therefore the aim of our study was to analyze if there are any changes occurring in the mitochondrial DNA of extraocular muscles in children that underwent strabismus surgery in our clinic. Methods: MtDNA was isolated from the tissue material using the Qiagen kit. Assessment of mtDNA mutations was performed by next-generation sequencing (NGS) using the Illumina MiSeq protocol. Results: The examination revealed the presence of atrophic changes in muscle fibers. NGS evaluation revealed a dominant genetic mutation in the ANT1 gene in 12 of the 15 patients examined. Conclusions: The presented results constitute the beginning of research on changes in mtDNA occurring in the muscles of children with strabismus surgery. Further studies are necessary in the context of resolving the transcriptomic differences between strabismic and non-strabismic EOMs. Better understanding of the molecular genetics of strabismus will lead to improved knowledge of the disease mechanisms and ultimately to a more effective treatment.

Introduction: Percutaneous endoscopic gastrostomy (PEG) has become the primary procedure for long-term enteral nutrition of most, but not all patients with dysphagia. Still in some patients gastrostomy may only be performed with open surgical technique (SG). Finally, in some patients due to relative contraindications to both methods, surgeons have to choose one of them., Aim: To compare PEG with SG in terms of effectiveness and safety., Material and Methods: A retrospective study of 612 patients with dysphagia, who underwent PEG (573) or SG (39) was conducted. Authors analysed effectiveness of PEG and SG procedures as well as the type, frequency and treatment methods of complications classified according to Clavien-Dindo Classification., Results: The rate of all complications was significantly lower for PEG than for SG and a significant effect of the treatment type on the probability of serious complications was observed - notably lower after PEG (OR = 0.21, 95% CI: 0.05-0.8, p = 0.02). The 30-day mortality rate was 1.74% for PEG and 0% for SG. PEG patients who required laparotomy were over 30 times more likely to die than others. No significant effect of the nutrition status on the probability of serious complications was observed (OR = 0.83, 95% CI: 0.51-1.34, p = 0.46)., Conclusions: A significant effect of the treatment type on the probability of serious complications was confirmed. This result was robust to the preoperative patients' nutrition status which was found to be insignificant. A lower risk of postoperative complications, a relatively easy procedure make PEG a procedure of choice in patients with dysphagia., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2022 Fundacja Videochirurgii.)

This presented work investigate the bio-convections effects of the magnetized time dependent axisymmetric flow of Carreau-nanomaterial performances with multiple slip effects over a stretching sheet. The momentum, heat, concentration and density of motile micro-organism are renovated into the system of equation via using well known similarity revolution. Well known Mathematical computational techniques and software (i.e. bvp4c and MATLAB) are used to draw graphical and tabular results. Velocity profile equation [Formula: see text], energy equation [Formula: see text], volumetric nanoparticles [Formula: see text], density motile microorganism [Formula: see text].The Carreau viscosity model is use to reduce the viscosity of fluid when [Formula: see text] and [Formula: see text]. Besides we moderate this into power law index with [Formula: see text] and [Formula: see text] partial slip condition of velocity is also instigated at the surface. Gravity dependent gyrotactic nanoparticles are utilized for well observing axisymmetric flow with convective boundary layer condition and comparatively better heat transfer rate result and applicable to maximum realistic approach., (© 2022. The Author(s).)

The reliability of the usage of a splitter plate (passive control device) downstream of the obstacle, in suppressing the fluid forces on a circular obstacle of diameter [Formula: see text] is studied in this paper. The first parameter of the current study is the attachment of a splitter plate of various lengths [Formula: see text] with the obstacle, whereas the gap separation [Formula: see text] between the splitter plate and the obstacle, is used as a second parameter. The control elements of the first and second parameters are varied from [Formula: see text] to [Formula: see text]. For the attached splitter plates of lengths [Formula: see text] and [Formula: see text], the oscillatory behavior of transient flow at [Formula: see text] is successfully controlled. For the gap separation, [Formula: see text] and [Formula: see text] similar results are obtained. However, it is observed that a splitter plate of too short length and a plate located at the inappropriate gap from the obstacle, are worthless. A computational strategy based on the finite element method is utilized due to the complicated representative equations. For a clear physical depiction of the problem, velocity and pressure plots have been provided. Drag and lift coefficients the hydrodynamic benchmark values are also evaluated in a graphical representation surrounding the obstacle's peripheral surface as well as the splitter plate. In a conclusion, a splitter plate can function to control fluid forces whether it is attached or detached, based on plate length and gap separation between obstacle and plate, respectively., (© 2022. The Author(s).)

The communication describes a theoretical framework for tangent hyperbolic fluid of nano-biofilm due to an extending or shrinking sheet that comprises a stagnation point flow, chemical reaction with activation energy, and bioconvection of gyrotactic microorganisms. The varying transport features due to dynamic viscosity, thermal conductivity, nano-particle mass permeability and microbe organisms diffusivity are taken into account for the novelty of this work. The inspiration is developed to enhance heat transfer. A set of leading partial differential equations is formed along with appropriate boundary constraints. Using similarity transformations, the basic formulation is transitioned into non-linear differential equations. To produce observational data, the shooting technique and Runge-Kutta fourth order method are employed. The coding of numerical scheme is developed in Matlab script. The visual representation of the effects of diverse fluid transport properties and distinctive parameters on speed, temperature, concentration and motile density are evaluated. The velocity become faster when the parameters [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are enhanced. Brownian motion, thermal conductivity, heat generation as well as thermophoresis factors all strengthen the temperature distribution, however the nano-particle concentration profile is enhanced as the nano-particle mass conductivity variable, activation energy as well as the thermophoresis variable are boosted. The microorganism density improves significantly when the microorganism diffusivity factor increases. The skin friction, Sherwood number, Nusselt number and motile density number decline against the incremented transport parameters., (© 2022. The Author(s).)

The unsteady energy and mass transport of magnetohydrodynamics (MHD) second grade nanofluid via an exponentially extending surface with Dufour and Soret effects are investigated in this study. Variable thermal conductivity and mixed convection effects are used to investigate the heat transfer mechanism. There are also new characteristics such as slip flow, viscous dissipation, Brownian motion, nonlinear thermal radiation, and thermophoresis. In the problem formulation, the boundary-layer approximation is used. Using the suitable transformations, the energy, momentum, and concentration equations are generated into non-linear ordinary differential equations (ODEs). The solution to the resultant problems was calculated via the Homotopy analysis method (HAM). The effects of environmental parameters on velocity, temperature, and concentration profiles are graphically depicted. When comparing the current results to the previous literature, there was also a satisfactory level of agreement. In comparison to a flow based on constant characteristics, the flow with variable thermal conductivity is shown to be significantly different and realistic. The temperature of the fluid grew in direct proportion to the thermophoresis motion, buoyancy ratio, and Brownian motion parameters. According to the findings, the slippery porous surface may be employed efficiently in chemical and mechanical sectors that deal with a variety of very viscous flows., (© 2022. The Author(s).)