Molybdenum Particles Research Articles

Tumor necrosis factor primes and metal particles activate the NLRP3 inflammasome in human primary macrophages

Aseptic loosening of total joint replacements is driven by a macrophage-mediated inflammatory reaction to implant-derived wear particles. Phagocytosis of implant debris has been suggested to activate the NLRP3 inflammasome leading to secretion of interleukin (IL)-1β. However, factors and molecular mechanisms driving the particle-induced inflammasome activation are yet to be fully elucidated. In this study, we investigated the inflammasome response of human primary macrophages to titanium, chromium, and molybdenum particles in vitro. We observed that particles alone were not sufficient to induce IL-1β secretion, but an additional priming signal—such as bacterial lipopolysaccharide (LPS)—was required to license the inflammasome activation. By using specific inhibitors against the inflammasome signaling pathway, we demonstrate that the particle-induced IL-1β secretion depended upon activation of the NLRP3 inflammasome. We further hypothesized that tumor necrosis factor (TNF) could substitute for LPS as a priming signal, and found that particle stimulation together with preceding TNF treatment resulted in inflammasome-dependent IL-1β production as well. Our results show that the NLRP3 inflammasome mediates wear particle responses in human primary macrophages, and its activation does not necessarily require the presence of bacterial components, but can be induced under aseptic conditions by TNF priming. Statement of SignificanceThis study was conducted to elucidate the molecular mechanisms of metal particle-induced IL-1β secretion in human primary macrophages. Production of this pro-inflammatory mediator from wear particle-activated macrophages has been associated with increased bone loss around total joint replacements—a condition eventually requiring revision surgery. Our results confirm that together with a co-stimulatory priming signal, particles of common implant metals elicit macrophage-mediated IL-1β secretion through activation of the NLRP3 inflammasome pathway. We also present a concept of TNF priming in this context, demonstrating that the particle-related IL-1β secretion can take place in a truly sterile environment. Thus, inhibition of inflammasome signaling appears a means to prevent wear particle-induced inflammation and development of peri‑prosthetic osteolysis.

Effect of ultrasonication and chelating agents on the dispersion of NiMo catalysts on carbon for Hydrodesulphurization

The effectiveness of the ultrasonication (US) and chelating agents in the dispersion of NiMo supported on activated carbon were examined. Accordingly, NiMo catalysts supported on carbon were prepared through co-impregnation of the support using US or the addition of chelating agents namely citric acid (CA) or ethylenediaminetetraacetic acid (EDTA) to facilitate the dispersion of the metals on the support. A surface area analyzer was used to provide the BET surface area measurements. Fourier-transform infrared spectroscopy (FTIR) and a powder X-ray diffractometer were used for the characterization of the structure of the prepared materials. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis of the morphology and surfaces of the mapping of the prepared material was obtained to get insight into the metal dispersion on the support. Results revealed a uniform dispersion of the nickel and molybdenum particles on carbon, especially in the case of using EDTA as a dispersion agent. Hydrodesulphurization of dibenzothiophene on the prepared catalysts was tested in a high-pressure batch reactor 1000 ppm dibenzothiophene in decalin as a model fuel. The results indicated that the chelating agents have a positive impact on hydrodesulphurization (HDS) efficacy and the EDTA has more effect than others. 97 % HDS was achieved using NiMo/AC(EDTA) while 94 % and 92 % were obtained using NiMo/AC(CA) and NiMo/AC(US), compared to 89 % without the use of US and chelating agents.

Network distribution of molybdenum among pure titanium powders for enhanced wear properties

A homogeneous network distribution of molybdenum particles among pure titanium particles was successfully produced by powder metallurgy. The Ti–xMo mixtures were consolidated by uniaxial hot pressing under a 10−4 mbar vacuum atmosphere at 950 °C for 30 min. The distribution of the molybdenum particles in the structure was investigated by optical and scanning electron microscopy in polished and etched conditions. The dry sliding wear properties of the Ti–xMo compacts and the Ti6Al4V alloy was carried out using a ball on disc test using a 250 m distance, 150 rpm and 20 N load. 100Cr6 steel was selected as the counterface material during the wear tests. The results showed that titanium alloy with a content of 10 wt.% Mo has the highest wear resistance within the Ti–xMo alloys. In addition, Ti–10Mo alloys showed an intensive wear resistance compared to the Ti6Al4V alloy.

Effect of molybdenum particles on thermal and mechanical properties of graphite flake/copper composites

Graphite flakes (GFs) in the GF/Cu composites generally fail to exert the advantage of the negative coefficient of thermal expansion (CTE) on account of the weak interfacial bonding between GFs and Cu. In this work, a rivet-joint strategy is adopted to surmount the dilemma. By introducing submicron Mo particles into the Cu matrix through the chemical synthesis process, various GF/Cu composites with the improved alignment of GFs via the method of tape-casting and hot-pressing sintering have been prepared. Due to the combined effects of Mo particle strengthened Cu and the rivet-joint interfacial architecture deriving from the in-situ synthesized MoxC, optimized thermal/mechanical properties of GF/Cu–Mo composites have been achieved. The 50 vol% GF/Cu composite with 1 wt% Mo shows the in-plane thermal conductivity of 598 W⋅m−1⋅K−1 and the through-plane CTE of −2.92×10−6K−1 (25–100 ∘C). Simultaneously, the bending strength is 40% higher than the 50 vol% GF/Cu composite. This strategy could promote the development of composites with improved combined structural and functional properties.

Synthesis of Intermetallic Phases in the Nb–Cd and Mo–Cd Systems by Ion-Plasma Sputtering and Atomic Layer Deposition of Metals in Vacuum

Niobium and molybdenum dicadmides (NbCd2 and MoCd2) have been synthesized using ion-plasma sputtering and codeposition of ultrafine niobium and cadmium or molybdenum and cadmium particles on unheated substrates at a Cd concentration near 66 at % in the film, without initiating reactions leading to the formation of these compounds. Their composition, structure, and unit-cell parameters have been determined by X-ray diffraction and transmission electron microscopy. The synthesized niobium and molybdenum dicadmides can be described by tetragonal unit cells with parameters a = 0.84357 nm and c = 0.54514 nm for the former and a = 0.78231 nm and c = 0.77039 nm for the latter, in which pairs of cadmium atoms reside on lateral faces.

Characterization of Alumina–Molybdenum Composites Prepared by Gel Casting Method

This work concerns the study of ceramic-metal composite materials processed by gel casting method. Due to limited possibilities of fabrication complex-shape elements obtained by classical methods of powder metallurgy (such as isostatic or uniaxial pressing) the colloidal processes are recently willingly applied in manufacturing of ceramic matrix composites. In the present work Al2O3–10 vol.% Mo composites were formed by aqueous gel casting process and sintered in argon atmosphere. Selected physical properties and phase composition have been described. The microstructure of the green and sintered samples was examined with a scanning electron microscope. Molybdenum particles were homogeneously distributed in the ceramic matrix. Moreover, Mo2C was formed during sintering process that had a positive contribution to enhancing the hardness of the composite. The composite after sintering was characterized by a density higher than 95% of theoretical density and high hardness. The performed studies have confirmed the possibility of application of gel casting method to produce Al2O3–Mo composite system.

Mo-La2O3 Multilayer Metallization Systems for High Temperature Surface Acoustic Wave Sensor Devices.

Developing advanced thin film materials is the key challenge in high-temperature applications of surface acoustic wave sensor devices. One hundred nanometer thick (Mo-LaO) multilayer systems were fabricated at room temperature on thermally oxidized (100) Si substrates (SiO/Si) to study the effect of lanthanum oxide on the electrical resistivity of molybdenum thin films and their high-temperature stability. The multilayer systems were deposited by the magnetron sputter deposition of extremely thin (≤1 nm) La interlayers in between adjacent Mo layers. After deposition of each La layer the process was interrupted for 25 to 60 min to oxidize the La using the residual oxygen in the high vacuum of the deposition chamber. The samples were annealed at 800 C in high vacuum for up to 120 h. In case of a 1 nm thick La interlayer in-between the Mo a continuous layer of LaO is formed. For thinner La layers an interlayer between adjacent Mo layers is observed consisting of a (LaO-Mo) mixed structure of molybdenum and nm-sized lanthanum oxide particles. Measurements show that the (Mo-LaO) multilayer systems on SiO/Si substrates are stable at least up to 800 C for 120 h in high vacuum conditions.

Composite Beads of Molybdenum Oxide Supported on Textured Silicon as an Oxidative Desulfurization Nanocatalyst

In the present work, Silicon powder was etched in the alkaline solution. The surface area of silicon powder increased after etching. Then, a nanocatalyst of molybdenum supported on textured silicon powder was successfully prepared. The nanocatalyst was characterized by scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and N2 adsorption-desorption. Molybdenum particles were dispersed on the entire surface of textured silicon beads. The spherical granules of this nanocatalyst were prepared by polyvinyl alcohol. The experimental results showed that the high oxidative desulfurization efficiency of dibenzothiophene were achieved ~93.7% using MoO3/Si/PVA/H2O2 within 150 min and at 60 °C. The oxidation rate was fitted to the pseudo-first-order kinetic model. The beads could be easily separated from the reaction solution and reused for 5 times. The remarkable advantages of this approach is a green, low- cost, reusable and effective method for oxidative desulfurization.

3D microstructure and crack pathways of toughened CaO–Al2O3–SiO2 glass by precipitation of hexagonal CaAl2Si2O8 crystal

AbstractWe investigated CaO–Al2O3–SiO2 glass partially crystallized with molybdenum particles as nucleating agents. Microstructure of the material was characterized as a house‐of‐cards structure composed of plate‐like crystals. Microcracks propagated along the crystal plane parallel to the double layer of SiO4/AlO4 tetrahedrons separated by layers of calcium atoms. To investigate the fracture behavior of the hexagonal CaAl2Si2O8 crystals, molecular dynamics simulations were performed, which demonstrated that a crack can be easily triggered by shear deformation along the calcium layer. Additionally, once a crack was generated in the calcium layer, it propagated rapidly, whereas the crack perpendicular to the calcium layer hardly propagated. This simulated behavior is consistent with the experimentally observed cleavage behavior of the hexagonal CaAl2Si2O8 crystal. The experimental and simulation results effectively explained the non‐elastic fracture behavior of the material.

Optimization of Friction Behavior Characteristics by Coating with Solid Lubricants

Increasing the lifetime of machine elements whose operation involves the development of friction processes and diminishing energy losses by friction can be achieved by using solid lubricants. In this regard, a method applied to improve the friction behavior of machine elements is electrostatic coating of the surfaces of interest with polyester layers that include particles of solid lubricants, such as molybdenum disulfide or graphite. Experimental research was conducted to highlight the influence of normal force, the concentration of solid lubricant particles in polyester, and specific sliding between surfaces involved in the friction process on the deposited layer’s lifetime and on the friction coefficient. Grey analysis was employed to identify sets of input factors that would lead to the most convenient values of the lifetime and energy friction losses when using polyester layers that incorporate molybdenum or graphite particles. Specialized software was elaborated in a MATLAB environment to use the grey relational analysis in identifying the optimal values of the process input factors for distinct weights of the output parameters.

Effect of Carbonization on CoMoS Catalyst supports in the Hydrodeoxygenation of Guaiacol as a Model Bio-Oil Compound

CoMoS/Cx/Sup Catalysts were prepared using 12-molybdophosphoric heteropolyacid and cobalt citrate. The supports were Al2O3, SiO2, nos, ZrO2, and carbonized Cr/Sup derived substrates (2 and 6 mass % carbon). The catalytic properties of these samples in the hydrodeoxygenation of guaiacol in a microflow apparatus were studied. With increasing carbon content in the supports, the length and number of MoS2 layers in the package increase in all the samples, apparently due to a decrease in the strength of the particle interaction with the more inert carbonized surface. Furthermore, the dispersion of the molybdenum particles on the catalyst surface, the content of promoter in the CoMoS active phase, and the extent of promotion of the crystallite edges differ significantly. The reasons were examined for the observed behavior and possible activity interrelationship during the hydrodeoxygenation of guaiacol with the parameters of the catalyst and active phase nanoparticles.

Structure of crystalline CaAl2Si2O8 precipitated in a CaO–Al2O3–SiO2 glass-ceramic

Metastable CaAl2Si2O8 crystalline phase was obtained via heat treatment of CaO–Al2O3–SiO2 glass with metallic molybdenum particles as nucleating agents. Its crystal structure was determined by aberration-corrected scanning transmission electron microscopy (Cs-STEM), Raman spectroscopy, and X-ray diffraction (XRD). Although the hexagonal structure was observed by Cs-STEM and Raman spectroscopy, Rietveld analysis revealed that a triclinic structure with space group P1 provided the best description of the crystal structure. The most appropriate lattice parameters were a = 5.1163(5) Å, b = 5.1155(5) Å, c = 15.0031(15) Å, α = 91.319(3)°, β = 88.172(3)°, and γ = 120.279(3)°. The c-axis layers composing the hexagonal plane were slightly distorted a few degrees from their arrangement in the hexagonal CaAl2Si2O8 crystal.

Design, Development and Performance Evaluation of Bio-Degradable Nano Cutting Fluid

Various cutting fluids are available in cutting fluid market to provide good machining performances for metal cutting industries. Incidentally, most of the cutting fluids are synthetic and semi synthetic in nature, though they are beneficial to the industries but they are posing health and environmental issues. Even if these cutting fluids have the sufficient properties required for good machining, the major constraints associated with these fluids are their nature of non-biodegradability and non-friendliness to the environment. To overcome these difficulties, intense research is carried out to develop the biodegradable and effective cutting fluid. In this research, a novel castor oil based cutting fluid infused with nano molybdenum (MoS2) particles has been developed and its various machining properties have been investigated. Various important cutting parameters like surface roughness, tool life, cutting force were investigated using this newly developed biodegradable nano fluid as a cutting fluid. Comparative experimental studies have also been done with sunflower oil blend and conventional synthetic oil. Observed results validated that the newly developed castor oil based nano fluid improves the surface finish, too life by minimizing the cutting force developed to the considerable extent.

Mesoporous MoSe2/C composite as anode material for sodium/lithium ion batteries

A mesoporous MoSe2/C composite is synthesized through a nano-casting technique along with heat treatment. Nano-silica particles are used as templates to create mesopores. Homogeneously dispersed Molybdenum and selenium particles in the starch substrate are reacted with each other to formed MoSe2 nanosheets when subjected to heat-treatment. Meanwhile, the starch is carbonized into carbon. The mesoporous MoSe2/C composite is investigated as an anode material for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). It presents good storage capacity for both lithium ions and sodium ions. Under the current density of 200 mA g−1, the mesoporous MoSe2/C composite exhibits reversible capacity of 618 mA h g−1 for LIBs and 360 mA h g−1 for SIBs after 300 cycles. The superior electrochemical performance could be ascribed to the mesoporous structure of MoSe2/C composite which provides sufficient space for accommodating huge volumetric expansion and the charge product, selenium.

Precipitation-Strengthened and Microlayered Bulk Copper- and Molybdenum-Based Nanocrystalline Materials Produced by High-Speed Electron-Beam Evaporation–Condensation in Vacuum: Structure and Phase Composition

The phase composition and structurization of three types of copper and molybdenum composite materials, 0.8 to 5 mm thick, which were condensed from the vapor phase at substrate temperatures 700 and 900°C, are considered: precipitation-strengthened composites, microlayered composites with alternating copper and molybdenum layers 1 to 10 μm thick, and bulk nanocrystalline composites with alternating layers thinner than 0.5 μm. Standard precipitation-strengthened Cu- and Mo-based materials condensed from the vapor phase at substrate temperatures 700–900°C can be produced over a relatively narrow composition range of the strengthening phase (0.1–3 wt.% Mo). When Mo content is 3–5 wt.%, the molybdenum particles change their shape from round to acicular and become discontinuous chains oriented perpendicularly to the vapor flow. If there is more than 5 wt.% of the second phase, the condensed composite materials (CCMs) show a layered structure. The layered structure can be observed in other CCM types (Cu–W, Cu–Cr, NiCrAlTi–Al2O3). Layered copper and molybdenum CCMs, 6 mm thick, produced on a rotating substrate heated to 700 ± 30°C have been experimentally confirmed to belong to bulk nanocrystalline materials.

Fabrication of homogeneous Mo-Cu composites using spherical molybdenum powders prepared by thermal plasma spheroidization process

In this work, spherical and dense molybdenum particles with the average particle size of 16.6 μm were synthesized by thermal plasma spheroidization process, and further used to fabricate homogeneous Mo-25 wt% Cu composites by infiltration method. The influence of infiltration temperature and holding time on the microstructure and properties of obtained Mo-Cu composites was investigated, and experimental results show that homogeneous Mo-Cu composites with high densification are obtained and the smooth surface of pores could facilitate the infiltration process. Specially, 98.6% of relative density of Mo-Cu composites is achieved and less than 10% irregular particles existing in spherical powders induce closed or half-connected pores in porous Mo skeleton, which shows adverse effect on full dense Mo-Cu composites obtaining. In addition, the highest microhardness of Mo-Cu composites (199 ± 3.6 Hv) is obtained when infiltrated at 1300 °C for 1 h. Moreover, the maximum value of thermal conductivity (TC) of Mo-Cu composites is 154 W/(m·K), and this is lower than that predicted by theoretical models, which may be due to the small amounts of carbon in Mo-Cu composites and non-full dense of Mo-Cu composites. Furthermore, the carbon in porous skeleton could be well removed by controlling the atmosphere of sintering process. Importantly, Mo-25 wt% Cu composites fabricated by irregular particles exhibit non-uniform microstructure and low TC compared to that prepared by spherical particles, which would be due to the uneven pore distribution and closed pores in porous skeleton fabricated by irregular particles. These results well illustrate the superiority of spherical molybdenum particles on fabrication homogeneous Mo-Cu composites.

The influence of arabic gum on the catalytic properties of Ni-Mo alloy coatings to intensify hydrogen evolution reaction

PurposeBecause of its wide applications in the industry, the electrodeposition of Ni/Mo as corrosion barrier and decorative coating took the attention of numerous researchers. This paper aims to study the effect of electroplating current density on different characteristics of Ni/Mo alloy coatings, especially on the morphology and electrochemical comportment in 3.5 per cent NaCl corrosion medium.Design/methodology/approachIn this paper, the authors have used electrodeposition technique to codeposite molybdenum particles in nickel matrix as protective coating against corrosion attacks, in addition to test the intensification of hydrogen reaction of this alloy coatings using EIS technique.FindingsNi-Mo alloy coating is well adherent to the substrate. The deposited Ni-Mo was observed to be fissured and porous in morphology. The main phases identified in different exposed coatings are MoNi4, Ni3Mo and Mo1.24Ni0.76. The effect of applied current density on electrochemical properties was studied. Inhibitory efficiency of gum arabic was controlled by the electroplating current density.Originality/valueIn this paper, the authors report on the presence of Mo particles in Ni matrix also the effect of electroplating current density on different properties of alloy coatings Ni/Mo. This is significant because it reports on the effect of current density on Ni/Mo electrodeposited at economic conditions like low temperature and moderate pH. Moreover, this paper gives a solution to the corrosion of crude oil desalter by using Ni-Mo coatings and then injecting a small amount of gum arabic in the oil pipeline before dissalement which gives long life to the reactor.

Selective conversion of methane to aromatic hydrocarbons on large crystallite zeolite catalysts with mesoporous structure

Large crystallite mesoporous MFI (ZSM-5) zeolite was synthesized by using carbon nano-powder as a secondary template. The surface properties, morphological and phase composition of the synthesized material and of the commercial ZSM-5 (Zeolyst) zeolite were studied by nitrogen porosimetry, XRD and scanning electron microscopy. The results showed that the volume of mesopores volume increases with development of a secondary mesoporosity in the structure of zeolite. The obtained zeolite supports were used to prepare molybdenum-containing catalysts for the methane aromatization by solid phase preparation technique. Based on the XPS data, molybdenum particles in these catalysts are characterized by more uniform size distribution. The formation of a secondary pore structure restrains the carbon deposit formation as well as increases the methane conversion and the yield of the aromatic compounds.

Increase of the Durability of the Ni3Al-based alloy Piercing Plug on Account of Reinforcing Particles

В данной работе слитки изготавливались методом выплавки электродов в открытой индукционной электрической печи СЭЛТ-20С/20 с последующим их электрошлаковым переплавом как с добавлением армирующих частиц молибдена в кристаллизатор методом равномерной подсыпки во время переплава, так и без добавления. Для выплавки использовались чистые шихтовые материалы без добавления отходов. Армирующие частицы молибдена были получены измельчением заготовок молибдена марки МШ-1 (ТУ 48-19-73-86) в планетарной мельнице. В результате проведения работы методом открытой индукционной выплавки было получено четыре электрода сплава на основе Ni3Al. Первые два электрода (№ 1 и 2) были подвергнуты стандартному электрошлаковому переплаву (ЭШП), а вторые два электрода (№ 3 и 4) были подвергнуты ЭШП с добавлением в кристаллизатор во время переплава порошка молибдена. Из всех полученных слитков были изготовлены прошивные оправки, которые испытывались при прошивке прутков коррозионно-стойкой стали марки 08Х18Н10Т-Ш. При помощи оправок, изготовленных из слитков № 1 и 2, было прошито 7 и 6 прутков соответственно, а при помощи оправок из слитков № 3 и 4 было прошито 11 и 12 прутков соответственно. Полученные результаты показали, что возможно повысить стойкость оправок из сплава на основе интерметаллида Ni3Al при прошивке прутков из стали марки 08Х18Н10Т-Ш на 76 % за счет повышения жаропрочных характеристик сплава армирующими частицами из порошка молибдена, вводимыми в процессе проведения ЭШП.

Nucleation and growth of hexagonal CaAl2Si2O8 crystals in CaO–Al2O3–SiO2 glass

Hexagonal CaAl2Si2O8 was precipitated inside of 25CaO–20Al2O3–55SiO2 (wt%) glass by heat treatment at 1050°C with MoO3 and carbon as nucleating agents. Transmission electron microscopy revealed that metallic molybdenum particles with sizes of∼200nm precipitated in the glass and served as heterogeneous nucleation sites for plane-like hexagonal CaAl2Si2O8 crystals with widths greater than 10μm and thicknesses of∼1μm. The thickness direction was the c-axis of hexagonal CaAl2Si2O8.