Search Results (7)

Ovarian cancer (OC) is the most lethal gynecological cancer globally. Its incidence and mortality consistently rise after menopause. While parity reduces the risk of OC, nulliparity during a woman’s fertile years increases it. Although the association between reproductive history and OC risk is well-established, the long-term impact of pregnancy on the postmenopausal human ovary has received little to no attention. Parity apparently delays the natural decline of the ovarian reserve, but this association also remains unexplored to date. Based on data from cellular, biochemical, and histological markers, as well as epidemiological studies, transcriptomic analyses, and gene knockout mouse models, we review compelling evidence suggesting a critical intraovarian interplay between the residual ovarian reserve and the ovarian surface epithelium (OSE) in the aged ovary. This interaction appears to be a key factor underlying the protective effect of parity on ovarian cancer (OC) risk. We propose that functional FSHR signaling in the remnant follicles of the aged multiparous ovary somehow counteracts the oxidative stress and subsequent chronic inflammation typically observed in the senescent ovary. This mechanism would minimize DNA damage, thereby lowering the probability of neoplastic transformation in the aged mammalian ovary. The precise mechanism by which pregnancy imprints such a long-term follicle–OSE crosstalk warrants further investigation. Full article

This study explores the potential of Arbutus unedo L. pomace, a by-product of the food industry, as a natural ingredient for skincare applications. In Portugal, A. unedo L. fruits are traditionally used to produce “Aguardente de Medronho”, a spirit with a protected geographical indication. The distillation process generates pomace, comprising skins, pulp remnants, seeds, and residual alcohol rich in phenolic compounds, whose levels are significantly increased during distillation. In addition to their documented high antioxidant content, these residues also display notable antimicrobial properties. However, their potential benefits for skin health have not yet been explored. The methodology entailed the preparation of the pomace extract and a comprehensive analysis of its polyphenolic content and antioxidant capacity under laboratory conditions and in preclinical cellular models. The by-products demonstrated a high polyphenol content and potent antioxidant activity, comparable to vitamin C. Bioscreening on human skin models (i.e., dermal fibroblasts and keratinocytes) revealed their ability to reduce reactive oxygen species (ROS) formation under oxidative stress in skin cells, highlighting their potential to mitigate skin aging and damage caused by environmental pollutants. Moreover, bioscreens in vitro revealed a high safety profile, without any interference with cell viability at concentrations up to 100 µg/mL. These findings support the use of A. unedo L. pomace extract as a sustainable ingredient for the development of antioxidant-rich and eco-friendly cosmetic or dermatologic products. Full article

The mechanical properties of a defect-free laser melting (PBF-LB) deposit of an AISI 316L steel alloy were assessed by means of an instrumented indentation test (IIT), at both the macro- and nano-scales. The inherent non-equilibrium microstructure of the alloy was chemically homogenous and consisted of equiaxed grains and large-elongated grains (under the optical microscope) with irregular outlines composed of a much finer internal cell structure (under the scanning electron microscope). Berkovich and Vickers indenters were used to assess the indentation properties across individual grains (nano) and over multiple grains (macro), respectively. The nano-indentation over the X-Y plane revealed nearly constant indentation modulus across an individual grain but variable on average within different grains whose value depended on the relative orientation of the individual grain. The macro-indentation test was conducted to analyze the tensile-like properties of the polycrystalline SS 316L alloy over the X-Y and Y-Z planes. The macro-indentation test provided a reliable estimate of the ultimate tensile strength (UTS-like) of the alloy. Other indentation properties gave inconsistent results, and a post factum analysis was, therefore, conducted, by means of a new approach, to account for the presence of residual stresses. The already existing indentation data were supplemented with new repeated indentation tests to conduct a detailed analysis of the relaxation ability of compressive and tensile residual stresses. The developed methodology allows the effect of residual stresses and the reliability of measured macro-indentation properties to be examined as a function of a small group of indentation parameters. Full article

A vast majority of hard coal deposits in Poland have a multi-seam structure, hence the presence of mining remnants left from previous operations. The impact of those remnants (exploitation edges or residual pillars) can further intensify geomechanical phenomena occurring in the rock mass, leading to changes in the original state of stress. This applies to all layers within the rock strata, including thick and coherent ones (referred to as tremor-inducing layers) where the impacts of mining remnants are likely to trigger tremors, thus enhancing the rock bursts hazard. In the light of the geomechanical model of rock strata recalled in the study, it is assumed that homogeneous and isotropic elastic layers are found between the considered mining remnant (which is revealed as the stress distribution), and the rock medium modelled as a homogeneous and isotropic half-plane. Development of the state of stress in the bedded medium was brought down to the analysis of interacting elastic layers, where the biharmonic equation is satisfied for each layer and for each respective half-plane. This equation can be solved by the integral Fourrier transform method. The impacts of the exploitation edge and the residual pillar on the elastic strain energy in the tremor-inducing layer is illustrated by recalling the Burzyński’s stress criterion. Strain energy in the tremor-inducing layer was analysed for various deformation properties of the surrounding strata and for various methods of coal extraction from the seam underneath the tremor-inducing layer. The results of the study evidence that a change in deformation properties of strata in the vicinity of the tremor-inducing layer may affect the state of stress and strain energy, which impacts on the tremor hazard levels in the vicinity of mining remnants areas. Full article

Ti-6Al-4V is widely used in various fields of modern industry, but it is difficult to obtain an ultra-smooth surface of Ti-6Al-4V due to its poor machinability. In this article, ultraviolet-induced (UV-induced) nanoparticle colloid jet machining was utilized to carry out ultra-precision polishing of Ti-6Al-4V to improve the surface quality. The results of infrared differential spectroscopy before and after polishing show that new chemical bonds such as Ti-O-Ti (Al-O-Ti and V-O-Ti) appear on the Ti-6Al-4V workpiece surface, which indicates that the material of Ti-6Al-4V workpiece is removed through the chemical interaction between TiO₂ nanoparticles and workpiece surface in the process of UV-induced nanoparticle colloid jet machining. The comparison of metallographic structure of Ti-6Al-4V before and after polishing shows that the chemical activity and material removal rate of the primary α phase in Ti-6Al-4V is higher than that of the remnant β phase in UV-induced nanoparticle colloid jet machining, which lead to the well-distributed nano-scale surface peaks and valleys at regular intervals on the polished Ti-6Al-4V workpiece surface. After polishing, the longitudinal residual stress on the surface of Ti-6Al-4V workpiece decreases from 75 MPa to 67 MPa and the transverse stress decreases from 13 MPa to 3 MPa. The surface roughness of Ti-6Al-4V workpiece is reduced from Sa 76.7 nm to Sa 2.87 nm by UV-induced nanoparticle colloid jet machining. Full article

Ustilago maydis and Saccharomyces cerevisiae differ considerably in their response to water-transfer treatments. When stationary phase cells were transferred to pure water and incubated under limited supply of oxygen, the U. maydis cells suffered a catastrophic loss of viability while the S. cerevisiae population was virtually unaffected by the treatment. The major factor underlying the death of the U. maydis cells under those conditions was an oxygen-consuming cellular activity that generated a hypoxic environment, thereby inducing oxidative stress and accumulation of reactive oxygen species, which resulted in lethality. Importantly, a small residue of U. maydis cells that did survive was able to resume growth and repopulate up to the initial culture density when sufficient aeration was restored. The regrowth was dependent on the cellular factors (Adr1, Did4, Kel1, and Tbp1), previously identified as required for repopulation, after killing with hydrogen peroxide. Surprisingly, the survivors were also able to resume growth under apparently hypoxic conditions, indicating that these remnant cells likely switched to a fermentative mode of growth. We discuss the findings in terms of their possible relevance to the eco-evolutionary adaptation of U. maydis to risky environments. Full article

Selective laser melting process has already been developed for many metallic materials, including steel, aluminum, and titanium. The quasistatic properties of these materials have been found to be comparable or even better than their conventionally-manufactured counterparts; however, for their reliable applications in operational components, their fatigue behavior plays a critical role, which is dominated by several process-related features, like surface roughness, remnant porosity, microstructure, and residual stresses, which are controlled by the processing features, like imparted energy density to the material, its corresponding solidification behavior, the cooling rate in the process, as well as post-processing treatments. This study investigates the influence of these parameters on the cyclic deformation behavior of selective laser melted as well as hybrid-manufactured aluminum alloys. The corresponding microstructural features and porosity conditions are evaluated for developing correlations between the process conditions to microstructure, the deformation behavior, and the corresponding fatigue lives. From the numerical point of view, damage development with respect to process-induced cyclic deformation behavior is assessed by the phase-field method, which has been identified as an appropriate method for the determination of fatigue life at the respective applied stress levels. Fatigue strength of SLM-processed parts is found better than their cast counterparts, while hybridization has further increased fatigue strength. No effect of test frequency on the fatigue life could be established. Full article