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On the role of magnesium in LiF:Mg,Ti thermoluminescent dosimeter
摘要： LiF doped with Mg and Ti is the most widely used thermoluminescent (TL) dosimeter for a large variety of applications. It has been argued that the Mg dopant is the most important defect in the TL process. Besides the common F-centre defects in LiF, optical absorption measurements have suggested the presence of Mg-related absorption bands at 380 nm (3.26 eV), and 310 nm (4.0 eV) when LiF:Mg is exposed to ionizing radiation, whose origin is not yet well understood. This work presents an investigation of the role of defects induced by Mg in LiF through electronic structure calculations. The calculations show that Mg interstitials induce a local lattice distortion characterized by the displacement of two opposite fluorine atoms, adjacent to the magnesium, away from their original sites by an average distance of 0.6 ? each, while the closest Li atoms are displaced by 0.1 ?. This defect introduces electronic states in the band-gap that can trap excess electrons produced during irradiation, thus enhancing the efficiency of the detector. Holes, on the other hand, are created and trapped in orbitals of mainly Mg-3s character. Additionally, the results suggest that irradiation can simultaneously remove a Li atom nearby a Mg interstitial; substitute a Li by a Mg atom or create a Li vacancy plus a Mg substitutional, giving rise to defects within the LiF gap that are more stable thermodynamically than the Mg interstitial itself.
关键词： magnesium dopant,LiF:Mg,Ti,thermoluminescent dosimeter,electronic structure calculations,defect states
更新于2025-09-23 15:21:01
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Grain refinement in laser remelted Mg-3Nd-1Gd-0.5Zr alloy
摘要： Columnar grains are normally favoured with the high cooling rate and steep thermal gradient in laser-based additive manufacturing. Here, we demonstrate that ?ne, fully equiaxed grains can be achieved in Mg-3Nd-1Gd-0.5Zr (EV31) alloy by laser surface remelting. The grains in the melt pool are remarkably re?ned from 74 μm to 3.5 μm, which can be attributed to the growth restriction effect, i.e. the constitutional supercooling formed by Zr solute during solidi?cation in combination with the high cooling rate imposed by laser surface remelting. This novel ?nding could be applied for the control of grain morphology and alloy design for additive manufacturing applications.
关键词： Solidi?cation microstructure,Grain re?ning,Laser treatment,Magnesium alloys,Rapid solidi?cation
更新于2025-09-23 15:19:57
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Effective Fixation of Carbon in ga??C <sub/>3</sub> N <sub/>4</sub> Enabled by Mga??Induced Selective Reconstruction
摘要： The methodology of metal-involved preparation for carbon materials is favored by researchers and has attracted tremendous attention. Decoupling this process and the underlying mechanism in detail are highly required. Herein, the intrinsic mechanism of carbon fixation in graphitic carbon nitride (g-C3N4) via the magnesium-involved carbonization process is reported and clarified. Magnesium can induce the displacement reaction with the small carbon nitride molecule generated by the pyrolysis of g-C3N4, thus efficiently fixing the carbon onto the in situ template of Mg3N2 product to avoid the direct volatilization. As a result, the N-doped carbon nanosheet frameworks with interconnected porous structure and suitable N content are constructed by reconstruction of carbon and nitrogen species, which exhibit a comparable photoelectric conversion efficiency (8.59%) and electrocatalytic performances to that of Pt (8.40%) for dye-sensitized solar cells.
关键词： magnesium inducement,reconstruction mechanism,dye-sensitized solar cells,graphitic carbon nitride (g-C3N4),tri-iodide reduction
更新于2025-09-23 15:19:57
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Switchable Photocurrent Generation in an Ultra-thin Resonant Cavity Solar Cell
摘要： Fabry-Perot type resonant nanocavities allow for broadband enhancement of light absorption in ultra-thin absorber layers. By introducing a switchable mirror, these thin film structures can be used as unique optical devices enabling interesting applications with switchable absorption. We use a thin film photovoltaic layer stack based on an amorphous germanium absorber layer and combine it with a thin Mg/Pd mirror to create a switchable solar cell. In this work we demonstrate, how we can switch the light absorption and hence the photocurrent generation of the thin film solar cell by changing the refractive index of Mg, due to hydrogen absorption. Our results show, how optical resonances in the absorber can be switched “on / off” by the change of optical properties of the magnesium reflector. The multi-layer system can be switched from a light absorbing and photocurrent generating state to a transparent window state with excellent color neutrality. We emphasize our study as an important step towards the realization of switchable photovoltaic windows, which paves the way for larger scale building integrated photovoltaic applications.
关键词： Ultra-thin absorber,light trapping,photovoltaic,amorphous germanium,switchable magnesium mirror,smart window
更新于2025-09-23 15:19:57
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Tents, Chairs, Tacos, Kites, and Rods: Shapes and Plasmonic Properties of Singly Twinned Magnesium Nanoparticles
摘要： Nanostructures of some metals can sustain light-driven electron oscillations called localized surface plasmon resonances, or LSPRs, that give rise to absorption, scattering, and local electric field enhancement. Their resonant frequency is dictated by the nanoparticle (NP) shape and size, fueling much research geared towards discovery and control of new structures. LSPR properties also depend on composition; traditional, rare and expensive noble metals (Ag, Au) are increasingly eclipsed by earth-abundant alternatives, with Mg being an exciting candidate capable of sustaining resonances across the ultraviolet, visible, and near-infrared spectral ranges. Here, we report numerical predictions and experimental verifications of a set of shapes based on Mg NPs displaying various twinning patterns including (10 1), (10 2), (10 3) and (11 1), that create tent, chair, taco and kite-shaped NPs, respectively. These are strikingly different from what is obtained for typical plasmonic metals because Mg crystallizes in a hexagonal close packed structure, as opposed to the cubic Al, Cu, Ag, and Au. A numerical survey of the optical response of the various structures, as well as the effect of size and aspect ratio, reveals their rich array of resonances, which are supported by single particle optical scattering experiments. Further, corresponding numerical and experimental studies of the near-field plasmon distribution via scanning transmission electron microscopy electron-energy loss spectroscopy unravels a mode nature and distribution that are unlike those of either hexagonal plates or cylindrical rods. These NPs, made from earth-abundant Mg, provide interesting ways to control light at the nanoscale across the ultraviolet, visible, and near-infrared spectral ranges.
关键词： nanoplasmonics,nanoparticle shape,magnesium nanoparticles,localized surface plasmon resonance,electron-energy loss spectroscopy,Wulff construction
更新于2025-09-23 15:19:57
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Laser Welding of ZE41 Mg Alloy: Experimental Investigations on the Effect of Parameters and Nondestructive Testing
摘要： Laser beam welding is an essential metal joining method for magnesium and its alloys with their growing applications in automotive, aerospace, marine, etc. In this research paper, the experimental modelling for laser beam welding of ZE41 Mg alloy and the mechanical and metallurgical characterisation after welding are reported. The effects of weld scan speed and laser beam power on the weld geometry for bead on plates of ZE41 Mg alloy using a continuous-wave CO2 laser system were analysed in this work. The microstructure, hardness, and radiography analysis were discussed. The results indicate the in?uence of laser parameters and the validity of the regression equations developed for the optimisation of process parameters.
关键词： ZE41 magnesium alloy,Hardness,Optimisation,X-ray radiography,Laser beam welding
更新于2025-09-23 15:19:57
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Visible-light-initiated Sonogashira coupling reactions over CuO/TiO <sub/>2</sub> nanocomposites
摘要： Magnesium lithospermate B (MLB) shows multiple biological activities including anti-oxidation and anti-proliferation in various diseases. However, the function of MLB in pulmonary arterial hypertension (PAH) is still unknown. This study aims to investigate the effect of MLB on hypoxia-induced phenotypic transformation of pulmonary arterial smooth muscle cells (PASMCs) and the underlying mechanisms. SD rats (or PASMCs) were exposed to 10% O2 for 3 weeks ( or 3% O2 for 48h) along with MLB or NADPH oxidase （NOX） inhibitor intervention. The effects of MLB on hemodynamics, pulmonary vascular remodeling and phenotypic transformation of PASMCs were observed first. Then, its effects on the protein levels of NOX (NOX2 and NOX4), ERK and p-ERK were examined. The results showed that MLB prevented the elevation in right ventricular systolic pressure and the increase in ratio of wall thickness to vessel external diameter of pulmonary arteries in PAH rats, and attenuated phenotypic transformation of PASMCs (decrease in α-smooth muscle actin while increase in osteopontin), accompanied by downregulation of NOX (NOX2 and NOX4) protein levels, decrease of ROS and H2O2 production, and suppression of the phosphorylation of ERK. NOX inhibitor (VAS2870) achieved similar results to that of MLB did in the hypoxia-treated PASMCs. Based on the observations, we conclude that MLB is able to prevent phenotypic transformation of pulmonary arteries in hypoxic PAH rats through suppression of NOX/ROS/ERK pathway, and MLB might have the potentials in PAH therapy.
关键词： pulmonary vascular remodeling,pulmonary arterial hypertension,Magnesium lithospermate B,NADPH oxidase,phenotypic transformation
更新于2025-09-19 17:15:36
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[ASME ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology - Boston, Massachusetts, USA (Monday 30 June 2014)] Volume 1: Combined Energy Cycles, CHP, CCHP, and Smart Grids; Concentrating Solar Power, Solar Thermochemistry and Thermal Energy Storage; Geothermal, Ocean, and Emerging Energy Technologies; Hydrogen Energy Technologies; Low/Zero Emission Power Plants and Carbon Sequestration; Photovoltaics; Wind Energy Systems and Technologies - Magnesium Hydride Slurry — A Better Answer to Hydrogen Storage
摘要： Hydrogen has many properties that make it an attractive energy storage medium for a sustainable future. But hydrogen is also difficult to store safely and cheaply. By storing hydrogen in an oil-based slurry with powdered magnesium hydride, cheap and safe hydrogen storage can be realized. This paper describes the characteristics and benefits of cycling hydrogen in and out of magnesium hydride slurry. Based on our experience with magnesium hydride slurry, we have performed a study to evaluate the cost effectiveness of applying bulk hydrogen storage, using magnesium hydride slurry, in a baseload wind power system that we will also discuss. This study concludes that a 150 MW baseload wind power system would produce an Internal Rate of Return (IRR) of 10% with an electric price of $0.088/kWh. The costs and performance characteristics of this power plant are described.
关键词： electricity storage,energy storage,hydrogen storage,magnesium hydride slurry,baseload wind farm
更新于2025-09-19 17:15:36
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Thiol–ene click reaction-induced fluorescence enhancement by altering the radiative rate for assaying butyrylcholinesterase activity
摘要： Bis‐ligated, homoleptic magnesium complexes 1–3 were synthesized through the reaction of 1 equiv. dibutyl magnesium with 2 equiv. β‐ketiminato ligands bearing different substituents on the nitrogen atom and 8 position on benzocyclohexanone. All of the complexes were identified by nuclear magnetic resonance (NMR) and X‐ray crystallography. Complexes 2 and 3 adopted distorted tetrahedral geometry around Mg, by chelating of two ancillary ligands, while complex 1 adopted a dimeric structure with penta‐coordination around Mg. These complexes can be used as efficient catalysts for ring‐opening polymerization of L‐lactide, ε‐caprolactone, δ‐valerolactone (δ‐VL) and trimethylene carbonate in the presence of alcohol as a co‐initiator. With the increasing steric bulk of the ancillary ligands, the catalytic activity of Mg complexes was improved significantly. Particularly, complex 3 having the largest steric hindrance showed excellent catalytic performance for the polymerization of δ‐VL. It could polymerize 800 equiv. δ‐VL in 10 min, and produce polyvalerolactone with narrow molecular weight distributions (Mw/Mn < 1.2) at 35°C or higher temperature. No transesterification side reaction was observed. Moreover, complex 3 exhibited good tolerance to excessive alcohol and an immortal polymerization characteristic. The mechanism studies by in situ NMR demonstrated a coordination‐insertion process. Besides, it revealed that the steric bulky substituents in the active species derived from the complex and alcohol prevented the metal center from deactivation.
关键词： ring‐opening polymerization,magnesium complex,polyester,δ‐valerolactone,bis‐ligated
更新于2025-09-19 17:15:36
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MgF2-Based Luminescing Ceramics
摘要： Results of investigation at 300 K of photo- and cathodoluminescence of the high-temperature optical ceramics synthesized for the first time based on MgF2 activated tungsten oxide are presented.
关键词： luminescence,tungsten,ceramics,magnesium fluoride,excitation spectra,annealing
更新于2025-09-19 17:15:36