Search Results (47)

Constructing heterojunctions can combine the superior performance of different two-dimensional (2D) materials and eliminate the drawbacks of a single material, and modulating heterojunctions can enhance the capability and extend the application field. Here, we investigate the physical properties of the heterojunctions formed by the contact of different atom planes of Janus MoSSe (JMoSSe) and graphene (Gr), and regulate the Schottky barrier of the Gr/JMoSSe heterojunction by the number of layers and the electric field. Due to the difference in atomic electronegativity and surface work function (WF), the Gr/JSMoSe heterojunction formed by the contact of S atoms with Gr exhibits an n-type Schottky barrier, whereas the Gr/JSeMoS heterojunction formed by the contact of the Se atoms with Gr reveals a p-type Schottky barrier. Increasing the number of layers of JMoSSe allows the Gr/JMoSSe heterojunction to achieve the transition from Schottky contact to Ohmic contact. Moreover, under the control of an external electric field, the Gr/JMoSSe heterojunction can realize the transition among n-type Schottky barrier, p-type Schottky barrier, and Ohmic contact. The physical mechanism of the layer number and electric field modulation effect is analyzed in detail by the change in the interface electron charge transfer. Our results will contribute to the design and application of nanoelectronics and optoelectronic devices based on Gr/JMoSSe heterojunctions in the future. Full article

Two-dimensional (2D) material-based resistive random-access memory (RRAM) has emerged as a promising solution for neuromorphic computing and computing-in-memory architectures. Compared to conventional metal-oxide-based RRAM, the novel 2D material-based RRAM devices demonstrate lower power consumption, higher integration density, and reduced performance variability, benefiting from their atomic-scale thickness and ultra-flat surfaces. Remarkably, 2D layered metal oxides retain these advantages while preserving the merits of traditional metal oxides, including their low cost and high environmental stability. Through a multi-step dry transfer process, we fabricated a Pd-MoO₃-Ag RRAM device featuring 2D α-MoO₃ as the resistive switching layer, with Pd and Ag serving as inert and active electrodes, respectively. Resistive switching tests revealed an excellent operational stability, low write voltage (~0.5 V), high switching ratio (>10⁶), and multi-bit storage capability (≥3 bits). Nevertheless, the device exhibited a limited retention time (~2000 s). To overcome this limitation, we developed a Gr-MoO₃-Ag heterostructure by substituting the Pd electrode with graphene (Gr). This modification achieved a fivefold improvement in the retention time (>10⁴ s). These findings demonstrate that by controlling the type and thickness of 2D materials and resistive switching layers, RRAM devices with both high On/Off ratios and long-term data retention may be developed. Full article

Temperature and Cr content on the tensile and fracture mechanics properties of welded joints made of two Cr-Mo steels (A387 Gr. B and SA387 Gr. 91) are presented and analyzed. Tensile strength, yield stress and elongation, as well as the stress–strain curves are obtained by standard tensile tests using specimens extracted from welded joints. Fracture toughness testing was carried out to determine the critical stress intensity factor, K_Ic, and the critical crack length, a_c, for all three zones of the welded joint, parent metal (PM), heat-affected zone (HAZ) and weld metal (WM). Based on these results, the tensile and fracture mechanics properties of welded joints made of A387 Gr. B and SA387 Gr. 91 steels are compared and analyzed. Full article

W-Mo-Cu composites show promise for advanced applications, but their properties require optimization. In this study, a novel approach utilizing Cu-coated graphene (Cu@Gr) reinforcement with skeleton relative density adjustment was employed to tailor the microstructure and properties of W-Mo-Cu composites fabricated via infiltration sintering (1300 °C, 1.5 h). The results revealed that Cu@Gr significantly promoted sintering densification, modified the phase composition, and enhanced the properties of the composite. Specifically, the addition of 0.4 wt.% Cu@Gr resulted in a relative density of 98% for the composite, representing an 8% increase compared to the material without Cu@Gr. Furthermore, when higher amounts of Cu@Gr were incorporated, the composite consistently exhibited a high degree of densification. In addition to the primary W, Mo, and Cu phases, molybdenum carbide, Mo₂C, was formed at 0.4 wt.% Cu@Gr, with its content rising proportionally to graphene dosage. Notably, the composite containing 0.6 wt.% Cu@Gr exhibits the highest thermal conductivity and electrical conductivity, showing 64% and 73% increases, respectively, versus Cu@Gr-free samples. Additionally, although W-Mo green compact density variations (73–85%) did not compromise graphene-induced densification, a higher green compact density reduced the thermal/electrical conductivities but increased the hardness. These findings demonstrate that controlled Cu@Gr incorporation and green compact optimization synergistically improve the properties of W-Mo-Cu composites, providing insights into high-performance material design. Full article

This study presents a comparative analysis of gold nanoparticles electrodeposited on different two-dimensional materials used as electrode substrates, graphene (Gr) and MoS₂, or co-deposited with the metallic material MoS₂. The morphological and electrochemical data demonstrate the efficiency of the electrodeposition process and the preferability of gold nanoparticles for certain attachment sites depending on the nature of the material used as a substrate and the deposition method used. The electrocatalytic activity of the gold nanoparticles obtained in these configurations was evaluated via the oxidation of nitrite ions (NO₂⁻), using both qualitative and quantitative approaches, by cyclic voltammetry and amperometry techniques. The electrocatalytic activity of gold nanoparticles co-deposited with MoS₂ is superior compared to that of gold nanoparticles deposited either on bare gold electrodes or on 2D materials (graphene and MoS₂), showing good performance with a specific sensitivity of 1.043 μA µM⁻¹ cm⁻² on the linear range of 0.5–600 µM nitrite, with a limit of detection of 0.16 µM and good anti-interference ability. Full article

In this paper, the wear characteristics of 20GrNi2MoV bearing steel under different working conditions were investigated by finite element simulation considering microscopic grain size and pin-on-disk friction experiments, and the wear mechanism during friction and wear was explained, along with a finite element model that took initial grain size and material organization into account to predict the process of subsurface crack initiation during friction. The results show that high-speed and large-load conditions have a significant effect on the wear characteristics of dry friction of pinned disks. The effect of high speed and load will greatly reduce the time of the grinding stage, and the friction coefficient can quickly reach a stable state; the roughness of the surface of the friction pair increases with the increase in load, but the roughness shows a tendency to first increase and then decrease with the increase in sliding speed. Martensitic phase transformation occurs in the friction subsurface, and the decrease in Mn element content is one of the causes of cracks on the subsurface of the material; with the increase in load and speed, the damage form of the sample disk material is changed from abrasive wear and adhesive wear to the mixture of three kinds of wear: abrasive wear, adhesive wear, and cracks. In addition, the simulation of crack initiation and growth agrees well with the experiment, which proves the accuracy of crack prediction. This study provides a reference for crack initiation prediction in the study of pinned disk friction vises. Full article

Molten salt reactors (MSRs) offer advantages such as enhanced safety, reduced nuclear waste, and cost effectiveness. However, the corrosive nature of fluoride-based molten salts challenges the longevity of structural materials. Ni-based alloys, like Hastelloy N, have shown resistance to fluoride salt corrosion but suffer from issues like helium embrittlement caused by neutron irradiation. To address these concerns, the incorporation of graphene (Gr) into Ni-based alloys is being explored. Gr’s superior mechanical properties and irradiation tolerance make it a promising reinforcement material. In this study, a Ni-17Mo alloy, a simplified model of Hastelloy N, was combined with reduced graphene oxide (RGO) using powder metallurgy. The effects of milling time and sintering temperature on the microstructure and mechanical properties were systematically studied. The results indicated that optimal sintering at 1100 °C enhanced tensile strength and ductility. Additionally, RGO incorporation improved the alloy’s strength but reduced its elongation. This research highlights the potential of Gr-reinforced Ni-based alloys for advanced MSR applications, offering insights into fabrication techniques and their impact on material properties. Full article

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, which formed in different tectonic settings, including island arc, back arc, and mid-ocean ridge. This group has experienced a hornblende-hornfels grade of contact metamorphism due to the intrusion of the Late Triassic Degilbo Granite. The intrusion is a mildly oxidized I-type monzogranite that has geochemical characteristics intermediate between those of granitoids typically associated with Fe-Cu-Au and Sn-W-Mo skarn deposits. The skarn mineralogy indicates that there was an evolution from prograde to various retrograde assemblages. Prograde garnet (Adr_11-99Grs_1-78Alm_0-8Sps_0-11), clinopyroxene (Di_30-92Hd_7-65Jo_0-9), magnetite, and scapolite formed initially. Epidote and Cl-bearing amphibole (mainly ferropargasite) were the early retrograde minerals, followed by chlorite, calcite, actinolite, quartz, and sulfides. Late-stage retrograde reactions are indicated by the development of nontronite, calcite, and quartz. Gold is mainly associated with sulfide minerals in the retrograde sulfide stage. The fluids in equilibrium with the ore-stage calcites had δ¹³C and δ¹⁸O values that indicate deposition from magmatically derived fluids. The calculated δ¹⁸O values of the fluids in equilibrium with the skarn magnetite also suggest a magmatic origin. However, the fluids in equilibrium with epidote were a mixture of magmatic and meteoric water, and the fluids that deposited chlorite were at least partly meteoric. δD values for the retrograde amphibole and epidote fall within the common range for magmatic water. Late-stage chlorite was deposited from metasomatic fluids depleted in deuterium (D), implying a meteoric water origin. Sulfur isotopic compositions of the Biggenden sulfides are similar to other skarn deposits worldwide and indicate that sulfur was most probably derived from a magmatic source. Based on the strontium (⁸⁷Sr/⁸⁶Sr) and lead (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb) isotope ratios, the volcanic and sedimentary rocks of the Gympie Group may have contributed part of the metals to the hydrothermal fluids. Lead isotope data are also consistent with a close age relationship between the mineralization at Biggenden and the crystallization of the Degilbo Granite. Microthermometric analysis indicates that there is an overall decrease in fluid temperature and salinity from the prograde skarn to retrograde alterations. Fluid inclusions in prograde skarn calcite and garnet yield homogenization temperatures of 500 to 600 °C and have salinities up to 45 equivalent wt % NaCl. Fluid inclusions in quartz and calcite from the retrograde sulfide-stage homogenized between 280 and 360 °C and have lower salinities (5–15 equivalent wt % NaCl). In a favored genetic model, hydrothermal fluids originated from the Degilbo Granite at depth and migrated through the shear zone, intrusive contact, and permeable Gympie Group rocks and leached extra Fe and Ca and deposited magnetite upon reaction with the adjacent marble and basalt. Full article

The effect of casting and T6 heat treatment at 540 °C for 3 h, quenching in water, heating to 180 °C for 4 h and cooling at room temperature on the mechanical properties and thermal expansion of Al6063 with reinforcement of 10 wt.% SiC/1 wt.% Y₂O₃/3 wt.% Graphite, 3 wt.% MoS₂ was studied, comparing the properties of the material before and after treatment. The results of the tensile test found that the ultimate tensile stress (UTS) increased without reinforcement applied but decreased the elongation at breaking point (%El). This contrasts with the reinforcement applied group, which showed an increase in the UTS and %EL by 4.1% and 32.5% in Gr, 10.5% and 44.9% in MoS₂, respectively. Meanwhile, the UTS and %EL increased by 23.5% and 26.98% in Gr, 22.7% and 15.0% in MoS₂, respectively, after the T6. Cracking analysis in the treatment without the addition of reinforcement showed ductile and brittle fracture after casting, similar to the effects of being treated by T6, which was characterized by brittle fracture. This was contrary to the reinforcement-added treatment, which was characterized by ductile fracture before and after treatment. The thermal expansion coefficient (CTE) after treatment without reinforcement applied was reduced, while no significant difference was seen with reinforcement applied. Full article

Extensive research has been conducted to identify key proteins governing stress responses, virulence, and antimicrobial resistance, as well as to elucidate their interactions within Listeria monocytogenes. While these proteins hold promise as potential targets for novel strategies to control L. monocytogenes, given their critical roles in regulating the pathogen’s metabolism, additional analysis is needed to further assess their druggability—the chance of being effectively bound by small-molecule inhibitors. In this work, 535 binding pockets of 46 protein targets for known drugs (mainly antimicrobials) were first analyzed to extract 13 structural features (e.g., hydrophobicity) in a ligand–protein docking platform called Molsoft ICM Pro. The extracted features were used as inputs to develop a logistic regression model to assess the druggability of protein binding pockets, with a value of one if ligands can bind to the protein pocket. The developed druggability model was then used to evaluate 23 key proteins from L. monocytogenes that have been identified in the literature. The following proteins are predicted to be high-potential druggable targets: GroEL, FliH/FliI complex, FliG, FlhB, FlgL, FlgK, InlA, MogR, and PrfA. These findings serve as an initial point for future research to identify specific compounds that can inhibit druggable target proteins and to design experimental work to confirm their effectiveness as drug targets. Full article

Maternal obesity (MO) is associated with offspring cardiometabolic diseases that are hypothesized to be partly mediated by glucocorticoids. Therefore, we aimed to study fetal endothelial glucocorticoid sensitivity in an ovine model of MO. Rambouillet/Columbia ewes were fed either 100% (control) or 150% (MO) National Research Council recommendations from 60 d before mating until near-term (135 days gestation). Sheep umbilical vein and artery endothelial cells (ShUVECs and ShUAECs) were used to study glucocorticoid receptor (GR) expression and function in vitro. Dexamethasone dose–response studies of gene expression, activation of a glucocorticoid response element (GRE)-dependent luciferase reporter vector, and cytosolic/nuclear GR translocation were used to assess GR homeostasis. MO significantly increased basal GR protein levels in both ShUVECs and ShUAECs. Increased GR protein levels did not result in increased dexamethasone sensitivity in the regulation of key endothelial gene expression such as endothelial nitric oxide synthase, plasminogen activator inhibitor 1, vascular endothelial growth factor, or intercellular adhesion molecule 1. In ShUVECs, MO increased GRE-dependent transactivation and FKBP prolyl isomerase 5 (FKBP5) expression. ShUAECs showed generalized glucocorticoid resistance in both dietary groups. Finally, we found that ShUVECs were less sensitive to dexamethasone-induced activation of GR than human umbilical vein endothelial cells (HUVECs). These findings suggest that MO-mediated effects in the offspring endothelium could be further mediated by dysregulation of GR homeostasis in humans as compared with sheep. Full article

The Azegour Mo-Cu-W skarn deposit, located on the northern side of the Western High Atlas, occurs in lower Cambrian volcanic and sedimentary rocks. The mineralizations are linked to the hydrothermal alterations that affected carbonated layers of the lower Cambrian age during the intrusion of the calc-alkaline hyperaluminous Azegour granite. Four stages of the skarn and ore mineral deposition have been identified as follows. Firstly, (i) the early prograde stage and (ii) the late prograde stage. These prograde stages are characterized by anhydrous minerals (wollastonite, garnets, and pyroxenes) associated with scheelite mineralization. Based on mineral chemistry studies, the early prograde stage is dominated by andradite (Ad_{72.81–97.07}) and diopside (Di_{61.80–50.08}) indicating an oxidized skarn; on the other hand, the late prograde stage is characterized by a high portion of grossular (Gr_{66.88–93.72}) and hedenbergite (Hd_{50.49–86.73}) with a small ratio of almandine (Alm_2.84–34.99), indicating “strongly reduced” or “moderately reduced” conditions with low f(O₂). The next two stages are (iii) the early retrograde stage and (iv) the late retrograde stage, which contain hydrous minerals (vesuvianite, epidote, chlorite, muscovite, and amphibole) associated with sulfide. Fluid inclusions from pyroxene and quartz (prograde skarn stage) display high homogenization temperatures and high to low salinities (468.3 to >600 °C; 2.1 to >73.9 wt% NaCl equiv.). The boiling process formed major scheelite mineralization during prograde skarn development from dominated hydrothermal magmatic fluid solutions. By contrast, fluid inclusions associated with calcite–quartz–sulfide (retrograde skarn stage) record lower homogenization temperatures and low salinities (160 to 358 °C; 2.0 to 11.9 wt% NaCl equiv.). The distribution of the major inclusions types from the two paragenetic stages are along the trend line of fluids mixing in the salinity–homogenization temperature (magmatic water), illustrating the genesis of ore-forming fluid by mixing with fluids of low temperatures and salinities (metamorphic and meteoric waters). Full article

In this study, cotton fabric-reinforced phenolic resin (CPF) composites were modified by adding four two-dimensional fillers: graphitic carbon nitride (g-C₃N₄), graphite (Gr), molybdenum disulfide (MoS₂), and hexagonal boron nitride (h-BN). The tribological properties of these modified materials were investigated under dry friction and water lubrication conditions. The CPF/Gr composite exhibits significantly better tribological performance than the other three filler-modified CPF composites under dry friction, with a 24% reduction in friction coefficient and a 78% reduction in wear rate compared to the unmodified CPF composite. Under water lubrication conditions, all four fillers did not significantly alter the friction coefficient of the CPF composites. However, except for an excessive amount of Gr, the other three fillers can reduce the wear rate. Particularly in the case of 10% MoS₂ content, the wear rate decreased by 56%. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed for the analysis of the morphology and composition of the transfer films. Additionally, molecular dynamics (MD) simulations were conducted to investigate the adsorption effects of CPF/Gr and CPF/MoS₂ composites on the counterpart surface under both dry friction and water lubrication conditions. The difference in the adsorption capacity of CPF/Gr and CPF/MoS₂ composites on the counterpart, as well as the resulting formation of transfer films, accounts for the variation in tribological behavior between CPF/Gr and CPF/MoS₂ composites. By combining the lubrication properties of MoS₂ and Gr under dry friction and water lubrication conditions and using them as co-fillers, we can achieve a synergistic lubrication effect. Full article

This paper addresses peculiarities in the formation and adherence of a tribofilm on the wear track surface of antifriction PI- and PEI-based composites, as well as a transfer film (TF) on a steel counterface. It is shown that during hot pressing, PTFE nanoparticles melted and coalesced into micron-sized porous inclusions. In the PEI matrix, their dimensions were much larger (up to 30 µm) compared to those in the PI matrix (up to 6 µm). The phenomenon eliminated their role as effective uniformly distributed nanofillers, and the content of 5 wt.% was not always sufficient for the formation of a tribofilm or a significant decrease in the WR values. At the loaded content, the role of MoS₂ and graphite (Gr) microparticles was similar, although filling with MoS₂ microparticles more successfully solved the problem of adhering to a PTFE-containing tribofilm in the point tribological contact. This differed under the linear tribological contact. The higher roughness of the steel counterpart, as well as the larger area of its sliding surface with the same PTFE content in the three-component PI- and PEI-based composites, did not allow for a strong adherence of either the stable PTFE-containing tribofilm on the wear track surface or the TF on the steel counterpart. For the PEI-based composites, the inability to shield the steel counterpart from the more reactive polymer matrix, especially under the conditions of PTFE deficiency, was accompanied by multiple increases in the WR values, which were several times greater than that of neat PEI. Full article

Developing highly efficient and durable hydrogen evolution reaction (HER) electrocatalysts is crucial for addressing the energy and environmental challenges. Among the 2D-layered chalcogenides, MoSe₂ possesses superior features for HER catalysis. The van der Waals attractions and high surface energy, however, stack the MoSe₂ layers, resulting in a loss of edge active catalytic sites. In addition, MoSe₂ suffers from low intrinsic conductivity and weak electrical contact with active sites. To overcome the issues, this work presents a novel approach, wherein the in situ incorporated diethylene glycol solvent into the interlayers of MoSe₂ during synthesis when treated thermally in an inert atmosphere at 600 °C transformed into graphene (Gr). This widened the interlayer spacing of MoSe₂, thereby exposing more HER active edge sites with high conductivity offered by the incorporated Gr. The resulting MoSe₂-Gr composite exhibited a significantly enhanced HER catalytic activity compared to the pristine MoSe₂ in an acidic medium and demonstrated a superior HER catalytic activity compared to the state-of-the-art Pt/C catalyst, particularly at a high current density beyond ca. 55 mA cm⁻². Additionally, the MoSe₂-Gr catalyst demonstrated long-term electrochemical stability during HER. This work, thus, presents a facile and novel approach for obtaining an efficient MoSe₂ electrocatalyst applicable in green hydrogen production. Full article