Tungsten Ions Research Articles

The effect of tungsten ions on the structural, elastic moduli, and shielding characteristics of arsenic lead phosphate glasses

A series of phosphate glass with the following formulation was manufactured using the melt quenching procedure: 3As2O3 – 37PbO – (60 − 𝑥𝑥) P2O5- 𝑥𝑥 WO3, 𝑥𝑥 = (0 ≤ 𝑥𝑥 ≤ 5 mol. %). The glasses' physical and other structural characteristics were examined in depth. The basic structural properties of the materials were examined using a variety of characterization procedures, such as XRD and FT-IR. With increasing WO3 concentration, the phosphate network evolves, leading to depolymerization of the glass network, according to the FT-IR analysis. With increasing WO3, the physical, mechanical, and structural parameters were enhanced like glass density, longitudinal and shear speeds, and all elastic moduli. Because of P–O–W bonds in the glass network are stronger than P–O– P bonds, the radiation characteristics were enhanced as the content of WO3 increased. The interpretation of the parameters showed that the glass in the statement is an excellent candidate for photon shielding applications.

The Cytotoxicity of Tungsten Ions Derived from Nanoparticles Correlates with Pulmonary Toxicity.

Tungsten carbide nanoparticles (nano-WC) are prevalent in composite materials, and are attributed to their physical and chemical properties. Due to their small size, nano-WC particles can readily infiltrate biological organisms via the respiratory tract, thereby posing potential health hazards. Despite this, the studies addressing the cytotoxicity of nano-WC remain notably limited. To this purpose, the BEAS-2B and U937 cells were cultured in the presence of nano-WC. The significant cytotoxicity of nano-WC suspension was evaluated using a cellular LDH assay. To investigate the cytotoxic impact of tungsten ions (W6+) on cells, the ion chelator (EDTA-2Na) was used to adsorb W6+ from nano-WC suspension. Subsequent to this treatment, the modified nano-WC suspension was subjected to flow cytometry analysis to evaluate the rates of cellular apoptosis. According to the results, a decrease in W6+ could mitigate the cellular damage and enhance cell viability, which indicated that W6+ indeed exerted a significant cytotoxic influence on the cells. Overall, the present study provides valuable insight into the toxicological mechanisms underlying the exposure of lung cells to nano-WC, thereby reducing the environmental toxicant risk to human health.

Theoretical level energies and transition data for 4p[formula omitted]4d[formula omitted], 4p[formula omitted]4d[formula omitted] and 4p[formula omitted]4d[formula omitted]4f configurations of W[formula omitted] ion

The ab initio quasirelativistic approach developed specifically for the calculation of spectral parameters of highly charged ions has been used to determine transition data for the Mo-like tungsten ion W32+. The configuration interaction method is utilized to include electron correlation effects. The relativistic effects are taken into account in the Breit–Pauli approximation. Level energies, radiative lifetimes τ, Landé g-factors are determined for the ground configuration 4p64d6 and two excited configurations 4p54d7 and 4p64d54f. The radiative transition wavelengths λ, emission transition probabilities A, weighted oscillator strengths gf, and transition line strengths S for the electric dipole, electric quadrupole, electric octupole, magnetic dipole, and magnetic quadrupole transitions among the fine-structure levels of these configurations are produced. The uncertainties of computed spectroscopic parameters are evaluated.

Electron impact ionization cross sections of highly charged open L-shell tungsten ions

L-shell electron-impact ionization (EII) cross sections for highly charged tungsten ions were measured at incident electron energies of 29.10 and 38.92 keV using the Shanghai-EBIT. Resolved x-rays from radiative recombination (RR) processes were recorded with a high-purity Ge detector in a static electron energy scanning mode. Absolute EII cross sections were obtained by normalizing to the theoretical RR cross sections. The experimental results were compared with the calculated results using the relativistic distorted-wave method implemented in the flexible atomic code and the relativistic Lotz semi-empirical equation. The measurements showed general agreement with the calculated results by two theoretical methods for Li- to N-like W ions. The experimental uncertainties are not sufficiently small to discern the two theoretical results. Furthermore, the influence of Breit interaction on the EII cross sections of open L-shell tungsten ions was studied, and the effect is small but non-negligible. The measured EII cross sections of open L-shell tungsten ions would contribute to fusion plasma studies.

The effect of MOx (M = Zr, Ce, La, Y) additives on the electrochemical preparation of tungsten in eutectic Na2WO4–WO3 melt

In order to prepare dense and smooth tungsten coatings, a class of additives MOx (M = Zr, Ce, La, Y) were mixed into Na2WO4–WO3 molten salt. Composition and microstructure of tungsten coatings were characterized by X–ray diffraction (XRD), and scanning electron microscopy (SEM). Different MOx additives produce significant differences in the phase, micromorphology and performance of the coatings. The coatings electrodeposited in Na2WO4–WO3–CeO2 molten salt have the finest grains, resulting in the microhardness of coating surface reaches the maximum value of 643.5 HV. The thermal shock resistance in air atmosphere is related to the phase and grains size of the coatings. The electrodeposition mechanism was explored by cyclic voltammetry (CV), linear scan voltammetry (LSV), square wave voltammetry (SWV), chronoamperometry (CA) and open circuit chronopotentiometry (OCP). The results indicated that the electrodeposition of tungsten ions is W(VI) → W(IV) → W, and Zr4+ and Ce4+ ions are electroreduced in two steps, while La3+ and Y3+ are electroreduced in one step. The differences between cathodic electroreduction potential and overpotential induced by different additives were probed. What’s more, the relationship between micromorphology and performance of coatings is discussed.

Organ distribution of Nano-WC particles after repeated intratracheal instillation into the lungs of SD rats and subsequent organ injury

Nano-tungsten carbide (nano-WC) is widely used in composite materials due to its special physical and chemical properties. Owing to their small size, nano-WC nanoparticles easily enter organisms through the respiratory tract, which may cause health hazards. However, only a few studies have reported the toxicity of nano-WC. In this study, a 10 mg/kg nano-WC suspension and 0.9% normal saline were quantitatively perfused into the lungs of two groups of healthy male SD rats by tracheal instillation, and the in vivo pulmonary toxic effects were systematically evaluated. Additionally, as multiple organs and tissues are involved, systemic effects were observed throughout the body and mainly manifested as inflammatory damage. The concentrations of tungsten ions in various organs and alveolar lavage fluid were measured by ICP–MS, and the results showed that the lung was the target organ, as it had the highest concentration of ions. In addition, the abnormal increases in the tungsten ion concentrations in the liver and kidney may be closely related to the immune damage we observed. This study provides a theoretical basis and data support for the systematic evaluation of the health hazards of nano-WC and a reference for the safe use of nanomaterials.

In Situ Spectroscopic Identification and DFT-Assisted Prediction of the Valence and Structure of Tungsten Ions in a Cationic/Anionic Molten Salt System

Understanding the reduction mechanism and coordination of tungsten ions in molten salt is one of the key factors to improve the electrolysis efficiency of tungsten carbide. In situ spectroscopy combined with simulation calculation is a strong analytical technique for characterizing chemical species and their behaviors in molten salts. The tungsten ion group was investigated by in situ high-temperature and room-temperature spectroscopy combined with density functional theory (DFT) calculations. For the described in situ spectroscopic studies, a new setup was used, which allowed the registration of UV–vis spectra of tungsten ions in cationic and anionic molten salt systems. The DFT calculation results proved useful for estimating the trend of experimental spectra. Through experimental and theoretical studies, the tungsten ion groups in various molten salt systems were identified, and the effect of cations and anions in molten salt systems onto tungsten ion group formation could be elucidated.

Dense and hard TiWC protective coatings grown with tungsten ion irradiation using WC-HiPIMS/TiC-DCMS co-sputtering technique without external heating

Titanium tungsten carbide (TiWC) coatings are deposited by a combined high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) technique. No external heating is applied during deposition phase, instead, the thermally driven adatom mobility is substituted by heavy ion irradiation. DCMS sources equipped with titanium carbide targets provide constant neutral fluxes to establish the predominant coating structures, whereas tungsten carbide target in HiPIMS mode serves as the source of heavy metal-ions. Substrate bias of −60 V is synchronized to W+ ion-rich time domains of HiPIMS pulses to minimize the contribution from working gas ions. The influence of W+ ion flux intensity, controlled by varying peak target current density (JT), on film properties is investigated. X-ray photoelectron spectroscopy reveals the presence of over stoichiometric carbon forming an amorphous phase, the amount of which can be fine-tuned by varying JT. Changes in film composition as a function of JT are explained based on the in-situ ion mass spectroscopy analyses. Dense TiWC coatings by hybrid process exhibit hardness higher than 30 GPa, which are comparable to TiWC films deposited by DCMS with dc substrate bias and external heating. The relative energy consumption in the hybrid process is reduced by 77 % as compared to high-temperature DCMS processing.

Investigation of Role of Tungsten Ions on Structural and Optical Properties of Sodium Borosilicate Germanate Glass for Optoelectronic Applications

Investigation of Role of Tungsten Ions on Structural and Optical Properties of Sodium Borosilicate Germanate Glass for Optoelectronic Applications

EUV spectral shape variation of tungsten unresolved transition arrays in electron temperature range of 2–4 keV observed in the Large Helical Device

Spectroscopic studies of emissions released from tungsten ions combined with a pellet injection technique have been conducted in the Large Helical Device. The tungsten Unresolved Transition Array (UTA) spectrum was observed in the wavelength ranges of extreme ultraviolet (EUV) 6–60 Å and 130–340 Å, and the electron temperature dependence of the UTA spectral shape was investigated in the electron temperature region < 4.3 keV. The UTAs of W24+–W33+ at 20–33 Å, W37+–W42+ at 45–47 Å, W27+–W29+ at 48–55 Å, and W7+– W27+ at 170–210 Å were observed. Unidentified UTAs were also found at 230–270 Å and 280–320 Å. As the electron temperature increased further above 4 keV, the W37+–W42+ UTA at 45–47 Å was maintained, while the other UTAs became less intense.

Mechanisms of non-adiabatic charge-exchange transitions in slow collisions of W ions with He, Ar and Kr atoms

The study of slow collisions of heavy particles is a challenging task from both experimental and theoretical points of view. A powerful tool for the theoretical description of these collisions is the adiabatic theory of transitions in slow collisions developed by Solov’ev (1989), which is applied here to study low-energy charge exchange between tungsten ions and inert-gas atoms at 0.01–1 keV/u. It is found that the main mechanism of charge-exchange transitions in collisions of W+ ions with Ar and Kr atoms at energies below 1 keV/u is the rotational coupling associated with internuclear axis rotation in close collisions, while charge exchange between W8+ ions and He atoms is mainly due to the radial Landau–Zener type transitions. For all cases, potential curves as a function of the internuclear distance are calculated together with the charge-exchange cross sections. The cross sections obtained are compared with experimental data, showing good agreement and explaining the mechanisms of the transitions.

Influence of axial magnetic field on angular distribution of charge and energy of laser produced slow and fast tungsten ion groups

Here effect of magnetic field on the angular distribution of laser produced tungsten (W) ions is reported. Plasma plume was generated by irradiating surface of W target, placed inside a vacuum chamber under magnetic field of 0.23 T, by nanosecond pulsed laser beam. Angular distribution of W ion flux was measured with the help of an ion collector (IC) and explained under the framework of Anisimov model. Magnetic field clearly split the ion signals temporally into comparable fast and slow ion components and enhanced the intensity of fast ion group significantly. Enhancement of ion charge state with B was confirmed by Ion energy analyser (IEA). Theoretical fitting of bimodal ion signal suggested the existence of thermal and non-thermal component of nanosecond laser produced plasma. With magnetic field, a two fold increase in total charge of the fast ion component was observed. Magnetic field effect on ion energy was also investigated. The optical emission spectrum of W plasma was also recorded, and plasma parameters were measured in both the absence and presence of magnetic field. The rise of electron temperature and number density in presence of B confirmed the heating of W plasma by magnetic field.

Detecting and Characterizing Particulate Organic Nitrates with an Aerodyne Long-ToF Aerosol Mass Spectrometer.

Particulate organic nitrate (pON) can be a major part of secondary organic aerosol (SOA) and is commonly quantified by indirect means from aerosol mass spectrometer (AMS) data. However, pON quantification remains challenging. Here, we set out to quantify and characterize pON in the boreal forest, through direct field observations at Station for Measuring Ecosystem Atmosphere Relationships (SMEAR) II in Hyytiälä, Finland, and targeted single-precursor laboratory studies. We utilized a long time-of-flight AMS (LToF-AMS) for aerosol chemical characterization, with a particular focus to identify C x H y O z N+ ("CHON+") fragments. We estimate that during springtime at SMEAR II, pON (including both the organic and nitrate part) accounts for ∼10% of the particle mass concentration (calculated by the NO+/NO2 + method) and originates mainly from the NO3 radical oxidation of biogenic volatile organic compounds. The majority of the background nitrate aerosol measured is organic. The CHON+ fragment analysis was largely unsuccessful at SMEAR II, mainly due to low concentrations of the few detected fragments. However, our findings may be useful at other sites as we identified 80 unique CHON+ fragments from the laboratory measurements of SOA formed from NO3 radical oxidation of three pON precursors (β-pinene, limonene, and guaiacol). Finally, we noted a significant effect on ion identification during the LToF-AMS high-resolution data processing, resulting in too many ions being fit, depending on whether tungsten ions (W+) were used in the peak width determination. Although this phenomenon may be instrument-specific, we encourage all (LTOF-) AMS users to investigate this effect on their instrument to reduce the possibility of incorrect identifications.

Molecularly imprinted ratiometric fluorescence detection of tetracycline based on its fluorescence enhancement effect caused by tungsten trioxide quantum dots

This paper reports a novel probe developed based on the tungsten trioxide quantum dots (WO3-x QDs) and molecularly imprinted polymers for the detection of trace tetracycline (TC) in the complex food matrix. Tungsten ion (W6+) in WO3-x QDs has a fluorescence enhancement effect on TC, and TC has a fluorescence quenching effect on WO3-x QDs. The blue emission of the WO3-x QDs (λem = 470 nm) as a reference and the yellow emission of the TC (λem = 550 nm) as a response were utilized for the ratiometric fluorescence detection. In order to improve its selectivity, the molecular imprinting technology was combined to construct molecularly imprinted ratiometric fluorescent probes (MIRFPs). Therefore, the MIRFPs can not only selectively detect TC, but also realize the visual detection from blue to yellow. Under the optimal conditions, the linear ranges of 0.01 ∼ 10.0 μmol/L and 20.0 ∼ 80.0 μmol/L were obtained with the limits of detection of 3.23 nmol/L and 6.37 μmol/L, respectively. Furthermore, the MIRFPs had been successfully applied to the detection of TC in milk and eggs. The satisfactory recoveries were in the range of 92.7 ∼ 102.9 % with relative standard deviations (RSD, n = 3) below 1.59 %. This work offers a good strategy for the detection of food hazards.

Optimization of pulse bi-directional electrolysis in-situ synthesis of tungsten carbide by response surface methodology

The response surface methodology was used to optimize the parameters of pulse bi-directional electrolysis (PBE) in-situ synthesis of tungsten carbide (WC) in NaF-KF molten salt system. The process of PBE synthesis of WC is a short process method of in-situ synthesis of WC powders in molten salt electrolyte. WC were used both as cathode and anode. A symmetrical bi-directional pulse is applied between the two electrodes. Tungsten ions dissolved by forward pulse, and WC were produced in situ with carbon near the electrode during reverse pulse. During the research, it was found that the factors affecting the phase of the experimental product were Current intensity, Pulse period and Electrolysis duration. In this paper, the cathode and anodic dissolved mass and the Proportion of WC in the product were used as the response values. The Box-Behnken center combined test and response surface analysis are used to optimize the factors that affect significantly, and the optimal process parameters were determined. Finally, the model was experimentally verified. Under the optimized experimental conditions, high-performance tungsten carbide nanopowders were prepared with short-process and high-efficiency.

Green and efficient removal of sulfides using oxo-peroxo tungsten(VI)-MIL-101(Cr) nanoreactor as heterogeneous recyclable catalyst

Efficient removal of sulfide using a modified MIL-101(Cr) nanoreactor by Schiff base complex has been investigated using H2O2 as a green oxidant. In addition, a new oxo-peroxo tungsten(VI) complex has been synthesized successfully by treating WO3 with a tridentate ONO donor Schiff base ligand in the presence of H2O2. Different techniques have been used to characterize the complex, while the crystal structure was investigated using an X-ray crystallographic approach. A seven-coordinated tungsten ion with a deformed pentagonal–bipyramidal geometry was explored using single-crystal X-ray diffraction analysis. The [WO(O2)(L)(CH3OH)] (L: (E)-N'-(5-chloro-2-hydroxybenzylidene) iso nicotinohydrazide) complex has been screened for the sulfoxidation of aryl and alkyl sulfides with H2O2 as a homogeneous catalyst. Furthermore, Chloromethylated MIL-101(Cr) having a mesoporous structure has been used as a support for the immobilization of [WO(O2)(L)(CH3OH)] complex to produce a heterogeneous and recyclable catalyst. This heterogeneous catalyst is novel in its efficiency, as illustrated by its improved activity with reference to the homogeneous catalyst under the same reaction conditions. The heterogeneous structure displayed excellent reusability several times without losing activity due to covalent grafting between –CH2Cl and W(VI) Schiff base, which introduces high stable nanostructure without leaching the complex during the reaction.

Basicity, Optical Features, and Neutron/Charged Particle Attenuation Characteristics of P2O5-As2O3-PbO Glasses Doped with Tungsten Ions

Basicity, Optical Features, and Neutron/Charged Particle Attenuation Characteristics of P2O5-As2O3-PbO Glasses Doped with Tungsten Ions

Influence of surface temperature, ion impact energy, and bulk tungsten content on the sputtering of steels: In situ observations from plasma exposure in PSI-2

• PSI-2 deuterium plasma exposures of 3 RAFM steels. • In-situ measurement of relative sputtering yields by optical emission spectroscopy. • In-situ measurement of the evolution of surface morphology by IR camera. • Post-mortem measurement of tungsten enrichment by RBS, SEM and EDX. • Independent measurements allow to disentangle the impact on the erosion of Fe. This study presents results from PSI-2 deuterium plasma exposures of reduced-activation ferritic martensitic steels with different tungsten content at a peak plasma flux of 9 · 10 20 D/m 2 s and 420–920 K sample temperature. Via optical emission spectroscopy the relative sputtering yield of Fe and Cr, and via an infrared camera the evolution of surface morphology is studied in-situ in 2D. After the exposure, RBS, SEM and EDX reveal tungsten enrichment and the formation of surface structures. Due to the independent measurement of surface morphology and tungsten enrichment, it is possible to disentangle the impact of both effects on the erosion of Fe. As part of this study, we investigate the effects of tungsten content, sample temperature and ion impact energy. The results show a reduction of the sputtering yield, depending on the exposure conditions, up to a factor of 2 at 130 eV ion impact energy and 720 K sample temperature.

Flame synthesis of tungsten‐doped titanium‐dioxide nanoparticles using novel precursor combination of liquid titanium tetra‐isopropoxide and solid tungsten mesh

AbstractTungsten‐doped titanium‐dioxide (W‐TiO2) nanoparticles are successfully synthesized using a multiple‐diffusion‐flame burner with a separate center tube. Vaporized titanium tetra‐isopropoxide (TTIP) precursor issues from a center tube to produce TiO2 nanoparticles, while a tungsten mesh, suspended above the surrounding multiple over‐ventilated hydrogen diffusion flames, serves as the solid‐phase metal doping source. At a lower tungsten loading rate, W‐TiO2 nanoparticles are generated, as indicated by an obvious angle shift of 0.15° for the entire x‐ray diffraction spectrum. However, at a higher tungsten loading rate, homogenous nucleation of WOx occurs before or concurrently with TiO2 nucleation, producing mixed nanopowders, permitting fewer tungsten ions to be doped into TiO2. Ultraviolet–visible spectroscopic characterization reveals that the as‐synthesized W‐TiO2 nanoparticles possess augmented absorbing ability in the visible‐light wavelength range, where the band gap is reduced from 3.20 to 3.05 eV, compared with that for the nondoped TiO2 nanoparticles.

Electron-Impact Ionization of the Tungsten Ions: W38+ − W45+

In this manuscript, we present our calculations of detailed electron-impact single ionization cross-sections for tungsten ions, spanning charge states W38+− W45+. The level-to-level distorted-wave method implemented in the flexible atomic code (FAC) was used for calculation. Comparison between the present level-to-level distorted wave treatment and previous configuration-averaged calculations has been performed for the W45+ ion, and we explore the possible reason for the difference observed between two calculations. We demonstrate the importance of radiative damping on the total electron-impact ionization cross-section for the W43+ ion. Present calculations provide missing cross-sections for W38+− W45+. The data obtained are expected to be useful for modeling plasmas for fusion applications, especially for the ITER community.