Search Results (24,280)

With the rapid development of advanced machining technologies such as high-speed cutting, dry cutting, and ultra-precision cutting, as well as the widespread application of various difficult-to-machine materials, the surface degradation problems such as wear, oxidation, and delamination faced by tools in the service process have become increasingly prominent, seriously restricting the performance and service life of tools. Nanocoatings, with their distinct nano-effects, provide superior hardness, thermal stability, and tribological properties, making them an effective solution for cutting tools in increasingly demanding working environments. For example, the hardness of the CrAlN/TiSiN nano-multilayer coating can reach 41.59 GPa, which is much higher than that of a single CrAlN coating (34.5–35.8 GPa). This paper summarizes the most common nanocoating material design, coating deposition technologies, performance evaluation indicators, and characterization methods currently used in cutting tools. It also discusses how to improve nanocoating performance using modulation analysis of element content, coating composition, geometric structure, and coating thickness. Finally, this paper considers the future development of nanocoatings for cutting tools in light of recent research hotspots. Full article

The Gabal Um Samra (GUS) compound intrusion in the Eastern Desert of Egypt consists of a co-magmatic series of syenogranite and alkali feldspar granite. Accessory minerals (e.g., zircon, monazite, allanite) are abundant. Geochemically, the GUS intrusion is a classic A-type granite. It is extensively fractionated, enriched in large ion lithophile elements and high field strength elements, and depleted in Ba, Sr, K, and Ti. Normalized rare earth element patterns are nearly flat, without any lanthanide tetrad anomalies, but with distinct negative Eu anomalies (Eu/Eu* = 0.14–0.22) due to feldspar fractionation. Paired Zr-Hf and Y-Ho element systematics indicate igneous rather than hydrothermal processes. The petrogenesis of the comparatively unaltered GUS intrusion offers an opportunity to refine the standard model for post-collisional felsic magmatism in the Neoproterozoic Arabian–Nubian Shield. It is explained by the partial melting of juvenile crust induced by lithospheric delamination, followed by extensive fractional crystallization. A quantitative mass-balance model shows that the granite varieties of the GUS intrusion plausibly represent liquids along a single liquid line of descent; but, if so, the more evolved, later pulses display anomalous enrichment in Rb, Nb, Ta, U, and REE. The most plausible source for this enrichment is the extraction of small-degree residual melts from earlier pulses and the mixing of the melts into the later pulses, an energetically favorable process we call “auto-assimilation”. A quantitative model shows that the residual liquid after 97.5% crystallization of the syenogranite can fit the major oxide and trace element data in the alkali feldspar granite if 0.07% by mass of this melt is added to the evolving system for each 1% crystal fractionation by mass. The GUS intrusion represents an example of moderate rare metal enrichment and concentration to sub-economic grade by auto-assimilation. Similar processes may affect intrusions that feature higher grade mineralization, but the evidence is often obscured by the extensive alteration of those deposits. Full article

Syngenetic fluid inclusions in natural diamonds are indicators of the composition of fluids responsible for growth and crystallization conditions. The chloride concentration in saline fluid inclusions of natural diamonds reaches 50 wt%. We study the dissolution of diamonds in the H₂O-KCl-NaCl system at temperatures of 1200 °C and 1400 °C and a pressure of 5.5 GPa using a BARS high-pressure multi-anvil apparatus. Two scenarios of diamond dissolution were experimentally investigated: (i) metasomatism by saline brines at high oxygen fugacity of the magnetite–hematite buffer; (ii) interaction with reduced carbon-unsaturated water–chloride fluid at low fO₂ imposed by the iron–wüstite buffer. It is found that the presence of alkaline chlorides in the aqueous fluid significantly accelerates diamond dissolution at high oxygen fugacity but inhibits the process under reduced conditions. The morphology of diamond dissolution features is controlled by the presence of water in the fluid over the entire range of the studied P-T-fO₂ conditions. Experimental results indicate that the interaction with oxidizing highly saline fluids during metasomatic events could negatively affect diamond preservation in mantle rocks and eventually lead to the formation of uneconomic kimberlites. Under reducing conditions, water–chloride fluids favor diamond preservation. Full article

The oxidization of sulfur dioxide (SO₂) occurs in the gas and liquid phase and this oxidation contributes to particulate matter and acid precipitation. The production of sulfate particles is significant because of their impact on climate, precipitation acidification, and human health. In this paper, the focus is on the oxidation of SO₂ and on the possibility of unknown heterogeneous reactions that may occur on sulfate aerosol surfaces. These results are based on the reanalysis of a foundational set of SO₂ laboratory oxidation measurements. The experiments involved two sets of photochemical studies of nitrous acid (HONO), nitrogen oxides (NO_x = NO + NO₂), SO₂, carbon monoxide (CO), and water vapor (H₂O) mixtures made in molecular nitrogen (N₂) with traces of molecular oxygen or in synthetic air. The reanalysis strongly suggests that there are uncharacterized processes for the oxidation of SO₂ that are nearly three times faster than the known gas-phase reactions. The uncharacterized processes may involve sulfate aerosol surface reactions in the presence of nitrogen oxides. If these processes can be included in current atmospheric chemistry models, greater conversion rates of SO₂ to sulfate aerosol will be calculated and this may reduce modeling bias. Full article

Surface modification of carbon fibers (CFs) is a critical step in preparing carbon fiber-reinforced composites. This study developed a continuous experimental process that integrates electrochemical anodic oxidation and chemical vapor deposition to fabricate carbon nanotubes/carbon fiber (CNTs/CF) reinforcements. The effects of temperature and hydrogen flow rate during CNT growth on the resulting reinforcements were systematically investigated. The surface morphology and mechanical properties of the modified materials were characterized using scanning electron microscopy, Raman spectroscopy, and single-fiber tensile testing. Employing an Fe_0.5Ni_0.5 bimetallic catalyst under optimized conditions (550 °C, H₂ flow rate: 0.45 mol/min, C₂H₂ flow rate: 0.30 mol/min), the resulting reinforcement exhibited an 8.7% increase in tensile strength compared to as-received CF. Full article

H13 steel, which was used as the material for shield machine cutter rings, required tempering to attain superior mechanical properties. The Cr-rich carbide that precipitated during the tempering process definitely decreased the corrosion resistance of the steel. Here, we added rare earth Yttrium to enhance the corrosion resistance of H13 steel. It was found that the inclusions were modified by adding yttrium in the steel, and the formation of Cr₂₃C₆ at the grain boundaries during tempering was suppressed. Furthermore, SKPFM measurements demonstrated that the surface potential of yttrium-containing inclusion was comparable to that of the surrounding matrix, thereby reducing the pitting susceptibility of H13 steel. Further investigation showed that yttrium decreased the normal stress range at grain boundaries during the tempering process, and effectively prevented C segregation. Thus, the number of Cr-depleted zones was decreased, and grain boundaries with active Cr atoms were increased. These active Cr atoms effectively sealed the ion channels between the matrix and NaCl solution within the Cr-rich oxide layer, thus improving localized corrosion resistance in the NaCl solution. On the other hand, the electrochemical test and SKPFM exhibited that yttrium reduced the potential loss during tempering, minimized the potential degradation of the matrix, and improved the corrosion resistance of H13 steel with yttrium. Accordingly, the corrosion loss of Y-bearing H13 steel was reduced by 46.6%. Full article

Supports used in heterogeneous metallic catalysts serve as a structural skeleton across which metallic nanoparticles are dispersed, but specific properties of the supports may also determine the behavior of these nanoparticles in catalytic processes. For example, it is known that among various properties of crystalline alkaline earth metal oxides serving as supports, the ability of their surface sites to donate electrons, that is their basicity, has an influence on the characteristics of the adsorbed metal. In the present work, the influence of MeO (Me = Mg, Ca, and Sr) basicity on the adsorption of Pb on the (100) surface of MeO crystals is studied by means of a dispersion-corrected density functional theory (DFT-D) computational method. The DFT-D calculations have characterized essential structural parameters, energetics, and the distribution of the electron charge for the Pb atoms and Pb dimers adsorbed at the regular O²⁻ and defective F_s centers of MeO(100). It has been observed that an increase in the basicity of MeO(100) in the sequence MgO < CaO < SrO results in a more energetically favorable effect of Pb adsorption, a stronger interaction between Pb and the surface, and a greater amount of electron charge acquired by the adsorbed Pb atoms and dimers. These findings contribute to a better understanding of how support basicity may modulate certain characteristics of MeO-supported metallic catalysts containing Pb as an additive. From a computational viewpoint, this work shows that the inclusion of spin–orbit relativistic correction in the DFT-D calculations leads to a significant reduction in the strength of the interaction between Pb and MeO(100), but it does not change the aforementioned trend in the strength of this interaction as a function of support basicity. Full article

Glyphosate, the active ingredient in many herbicides, has been extensively used in agricultural practices worldwide, leading to environmental persistence of the herbicide and its main metabolite, aminomethylphosphonic acid (AMPA), particularly in water and soil. Despite a short half-life in biological fluids, frequent detection of glyphosate and AMPA in urine samples suggests ongoing human exposure. Evidence indicates that glyphosate and AMPA may exert endocrine-disrupting effects on testicular function. Glyphosate exposure may disrupt the hypothalamic–pituitary–gonadal axis, impacting serum testosterone levels and other key hormones involved in spermatogenesis and fertility. It has also been shown to impair key cellular processes within the male reproductive system, including oxidative stress, mitochondrial dysfunction, and hormone biosynthesis. These findings raise concerns about the herbicide’s ability to compromise sperm production, structure, and motility, which are crucial factors for male fertility. This review examines the mechanisms underlying glyphosate-induced testicular toxicity, emphasizing endocrine disruption, oxidative stress, and mitochondrial dysfunction, and highlights the need for further studies on long-term effects across different life stages and genetic backgrounds. Glyphosate-induced testicular toxicity can be counteracted by antioxidant agents, which emerge as promising therapeutic strategies in need of further investigation. Full article

Stuffing sand, as a critical auxiliary material, plays an important role in ladle teeming during the continuous casting process and is closely related to steel cleanliness. Based on thermodynamic calculations, a melting test in a vacuum induction furnace, and industrial statistical data analysis, the reoxidation of IF steel caused by conventional Cr₂O₃-based stuffing sand was investigated. The results show that Cr₂O₃-based stuffing sand is one of the main factors resulting in the reoxidation of IF steel. [Al] and [Ti] in IF steel can be oxidized by FeO, Cr₂O₃, and SiO₂ from the Cr₂O₃-based stuffing sand, which leads to the mass burning loss of [Al] and [Ti], thus resulting in the deterioration of steel cleanliness. After reoxidation caused by Cr₂O₃-based stuffing sand, the [Cr] content in IF steel increases by 70 ppm on average. To avoid reoxidation pollution by conventional Cr₂O₃-based stuffing sand, a new kind of Al₂O₃-based stuffing sand with low reactivity was developed and applied in industrial production. After adopting this new kind of stuffing sand, the burning loss of [Al] and [Ti] decreases by 41.3% and 24.2%, respectively, and the total oxygen content (T.[O]) of the steel in the tundish decreases by 35.2% compared with the conventional Cr₂O₃-based stuffing sand. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and the leading cause of dementia, with current therapies offering only limited symptomatic relief and lacking disease-modifying efficacy. Addressing this critical therapeutic gap, natural multi-target compounds like mulberroside A (MsA)—a bioactive glycoside from Morus alba L.—present promising alternatives. This study investigated MsA’s neuroprotective potential using scopolamine-induced AD-like mice and N2a/APP695swe cells. In vivo, MsA significantly ameliorated cognitive deficits and neuronal loss, concurrently enhancing cholinergic neurotransmission through increased acetylcholine levels and inhibited acetylcholinesterase (AChE)/butyrylcholinesterase (BChE) activities. MsA also upregulated neurotrophic factors (BDNF, CREB) in critical brain regions. In vitro, MsA restored cholinergic function, mitigated oxidative stress, and crucially reduced amyloid-β (Aβ) production by dual regulation of APP processing: promoting the non-amyloidogenic pathway via ADAM10 upregulation and inhibiting the amyloidogenic pathway via suppression of BACE1 and γ-secretase components. Mechanistically, these multi-target benefits were mediated by MsA’s activation of the PI3K/AKT pathway, which triggered downstream inhibitory phosphorylation of GSK3β—directly reduced tau hyperphosphorylation—and activation of CREB/BDNF signaling. Collectively, our findings demonstrate that MsA confers comprehensive neuroprotection against AD pathology by simultaneously targeting cholinergic dysfunction, oxidative stress, Aβ accumulation, tau phosphorylation, and impaired neurotrophic signaling, highlighting its strong therapeutic candidacy. Full article

This study focuses on the design, development and quality assessment of an innovative shelf-stable olive paste dip, aiming at the valorization of by-products of tomato processing and olive oil production (Product 1: OPD). Bioactive compounds (BACs), i.e., total carotenoids and phenolic components, were extracted from tomato and olive pomace, respectively. For further enrichment, BACs were incorporated in olive paste dips into a second product (OPDEnr) in encapsulated form (Product 2: OPD_Enr). The total carotenoids (TC) of OPD and OPD_Enr were 20.0 ± 2.0 and 30.2 ± 1.0 mg/kg, respectively. Similarly, the total phenolic content (TPC) and the antioxidant activity (AA) were 1.62 ± 0.08 and 3.05 ± 0.10 mg GAE/g, and 0.801 ± 0.075 and 0.976 ± 0.032 mg Trolox/g, respectively. The quality of the developed olive paste dip product prototypes was assessed using the Accelerated Shelf Life Testing (ASLT) methodology at a temperature range of 20–40 °C. Both OPD_Enr and OPD were microbiologically stable during storage (i.e., not exceeding 4 logCFU/g for total mesophilic counts), and no lipid oxidation evolution was observed (Peroxide Value, PV did not exceed 4 meq O₂/kg), while TC, TPC and AA values remained stable. The shelf life of OPD_Enr and OPD was determined based on the overall sensory quality and was found to be 120 and 211 d at 25 °C, respectively. OPD_Enr and OPD were characterized by a high quality (color and texture), with an overall sensory score of 8.0/9.0 and 9.0/9.0, respectively, in the acceptability–hedonic scale 1 (dislike extremely)-9 (like extremely), and they could potentially be consumed as an antioxidant-enriched olive paste dip. Full article

Nitrous oxide (N₂O) is a potent greenhouse gas, with emissions occurring mostly from agricultural soils, especially acidic soils. This research aimed to elucidate the response of soils dominated by nitrification-driven N₂O production to alkaline amendments, given that nitrification is a key process in N₂O emission. This study investigated the impact of an alkaline mineral amendment (CSMP) on N₂O emission, nitrification rate, and functional gene abundance. Using a robotic automated incubation system, CSMP both alone and in combination with urea was applied to two acidic soils (CL: pH 5.81; WS: pH 4.91). The results demonstrated that, relative to the CK, the CSMP-only treatment significantly increased N₂O emissions by 18.4-fold in these acidic soils, with a 61.6-fold increase in the U + CSMP treatment. This very large increase was driven by a rise in AOB-amoA abundance and a concurrent decline in AOA-amoA, which was confirmed by structural equation modeling, which showed that the increase in pH strongly influenced N₂O emission primarily through AOB-amoA. Although CSMP is effective for reversing soil acidification, its use must be carefully managed to prevent stimulation of N₂O emissions. Future strategies should explore combining CSMP with approaches that can mitigate nitrification while maintaining its soil improvement benefits. This study provides critical insights for developing balanced management practices that address both soil health and climate change mitigation in acidic agricultural systems. Full article

Resistive switching (RS) phenomena are nowadays one of the most studied topics in the area of microelectronics. It can be observed in Metal–Insulator–Metal (MIM) structures that are the basis of resistive switching random-access memories (RRAMs). In the case of commercial use of RRAMs, it is beneficial that the applied materials would have to be compatible with Complementary Metal-Oxide-Semiconductor (CMOS) technology. Fabricating methods of these materials can determine their stoichiometry and structural composition, which can have a detrimental impact on the electrical performance of manufactured devices. In this study, we present the influence of the Ar/N₂ ratio during reactive magnetron sputtering of titanium nitride (TiN) electrodes on the resistive switching behavior of MIM devices. We used silicon oxide (SiOx) as a dielectric layer, which was characterized by the same properties in all fabricated MIM structures. The composition of TiN thin layers was controlled by tuning the Ar/N₂ ratio during the deposition process. The fabricated conductive materials were characterized in terms of chemical and structural properties employing X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis. Structural characterization revealed that increasing the Ar content during the reactive sputtering process affects the crystallite size of the deposited TiN layer. The resulting crystallite sizes ranged from 8 Å to 757.4 Å. The I-V measurements of fabricated devices revealed that tuning the Ar/N₂ ratio during the deposition of TiN electrodes affects the RS behavior. Our work shows the importance of controlling the stoichiometry and structural parameters of electrodes on resistive switching phenomena. Full article

Environmental pollution driven by socioeconomic development has intensified the need for advanced and sustainable wastewater treatment technologies. Herein, TiO₂-based photocatalysis emerged as a promising solution due to its oxidative potential, chemical stability, and eco-friendliness but does have unavoidable immobilized recoverability challenges. Therefore, this study explored the challenges and prospects of TiO₂-based photocatalysis for the degradation of emerging contaminants in wastewater. A comprehensive keyword analysis was conducted by using a decade of publications retrieved from Google Scholar, Scopus, and Web of Science (WOS) databases via Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. From a pool of 518 refined publications, 318 significant keyword occurrences related to TiO₂-based photocatalysis advanced oxidation processes (AOPs) were revealed. The review delved into various types of AOP mechanisms and catalysts and highlighted the synergistic effect of process parameters and magnetization as recoverability potential for TiO₂-based photocatalysts. Furthermore, emerging strategies including surface modifications, doping, and hybrid AOP integrations were discussed to improve photocatalysis performance and industrial scalability. The study underscores the economic opportunity and environmental sustainability of degrading persistent organic pollutants by integrating a TiO₂-based photocatalytic system with a regenerative magnetic field into the water sector. Full article

All forms of vitamin A have a similar structure and physiological functions in the body. These compounds can be classified as retinoids, including moieties with a common structure of four isoprenoid units of natural or synthetic origin. Vitamin A is generally uptake from products of animal origin (retinol and its derivatives) or from plants as provitamin A (carotenoids). Vitamin A is fat-soluble, so it is easily absorbed and transported in the body. The main storage sites are the liver and adipose tissue. Excessive amounts of the vitamin may lead to the development of different abnormal processes in the human body. Apart from being crucial for retina conditions and functions and the immune system, vitamin A is also deeply involved in DNA repair mechanisms. Its antioxidant nature helps to reduce the oxidative damage to DNA by neutralizing free radicals and thus decreasing the oxidative stress. On the other hand, vitamin A deficiency leads to lower antioxidant enzyme activity, which results in the weakening of the defense system against free radicals. This study aims to elucidate the mechanisms of DNA repair and determine the role of carotenoids, vitamin A, and its derivatives as contributing factors in this process. This review synthesizes the current knowledge on the dual role of vitamin A in DNA integrity by examining the conditions under which it acts as a genotoxic agent versus a facilitator of DNA repair. This article also discusses the role of vitamin A in inhibiting oxidative stress and its anti- and pro-cancer impact. Full article