High-energy Processes Research Articles

Unveiling the Toxicity of Fine and Nano-Sized Airborne Particles Generated from Industrial Thermal Spraying Processes in Human Alveolar Epithelial Cells.

High-energy industrial processes have been associated with particle release into workplace air that can adversely affect workers’ health. The present study assessed the toxicity of incidental fine (PGFP) and nanoparticles (PGNP) emitted from atmospheric plasma (APS) and high-velocity oxy-fuel (HVOF) thermal spraying. Lactate dehydrogenase (LDH) release, 2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) metabolisation, intracellular reactive oxygen species (ROS) levels, cell cycle changes, histone H2AX phosphorylation (γ-H2AX) and DNA damage were evaluated in human alveolar epithelial cells at 24 h after exposure. Overall, HVOF particles were the most cytotoxic to human alveolar cells, with cell viability half-maximal inhibitory concentration (IC50) values of 20.18 µg/cm2 and 1.79 µg/cm2 for PGFP and PGNP, respectively. Only the highest tested concentration of APS-PGFP caused a slight decrease in cell viability. Particle uptake, cell cycle arrest at S + G2/M and γ-H2AX augmentation were observed after exposure to all tested particles. However, higher levels of γ-H2AX were found in cells exposed to APS-derived particles (~16%), while cells exposed to HVOF particles exhibited increased levels of oxidative damage (~17% tail intensity) and ROS (~184%). Accordingly, APS and HVOF particles seem to exert their genotoxic effects by different mechanisms, highlighting that the health risks of these process-generated particles at industrial settings should not be underestimated.

Multi-Layers Composite Plasma Coatings Based on Oxide Ceramics and M-Croll

The paper considers the influence of the parameters of the plasma spraying process on the technological characteristics of multilayer coatings based on nickel-chromium, nickel-chromium-aluminum-yttrium materials, oxide ceramics, intended for operation at high temperature and additional dynamic loads. The design of plasma coatings during their application (with subsequent high-energy processing) under such conditions requires a comprehensive solution – both the use of high-quality powder ingredients and the optimization of technological parameters. The plasma process of applying powder materials has been improved to obtain the maximum values of their utilization factors. The technological characteristics that affect the properties of plasma coatings are optimized, namely: the flow rates of the plasma-forming and materials-transporting gases, the flow rate of supplied powder materials, the current and voltage of the electric arc of the plasma torch, the distance from the plasma torch nozzle exit to the substrate. The paper presents the results of studies of the structure of coatings, performed using scanning electron microscopy. Their analysis has made it possible to form general regularities obtained by the action of radiation of compression plasma flows on coatings formed by air plasma. The considered structures are created using the processes of melting, compaction and high-speed cooling of plasma coatings. The main optimization indicators are the maximum local compaction and spillage of the obtained compositions with the absence of defects and destruction from the impact of compression plasma flows. The main effect during the action of radiation of a compression plasma flow on previously formed coatings is thermal. It contributes heating of the near-surface layer. When the coating is exposed to radiation of compression plasma flows, a remelted layer of oxides with a thickness of about 12–15 µm is created, smoothing the relief of the formed surface and creating a network of cracks on the surface, diverging into the depth of the coating. The liquid-phase processes occurring in the molten phase of the near-surface layers after exposure to compression plasma radiation change the structure of the layers and contribute to the modification of their mechanical properties. By smoothing the surface, increasing the density of the surface crystallized layer and minimizing macro-defects – pores or macrocracks – the mechanical characteristics of the coatings increase.

Sputtering FeCu nanoalloys as active sites for alkane formation in CO2 hydrogenation

Catalytic conversion of CO2 to high-value products is a crucial method to achieve targets of carbon dioxide emissions peak and carbon neutralization. However, realizing a controllable product distribution in a single CO2 hydrogenation process is of great challenge. Herein, we prepared the CuFe nanoalloy catalyst that directly transforms CO2 to alkanes using physical sputtering method in mild condition. The characteristic results show that the proximity between Cu and Fe is the crucial factor to tunable products among the different catalysts. The formation of unique coordination of FeCu4 nanoalloys from high-energy sputtering process provides close interaction between Cu and Fe, which is favorable to formation of low carbon paraffin, however, a distant proximity and weak interaction will increase the selectivity of olefins and alcohols. This work provides a general strategy for tuning target chemicals and enriches the viewpoints in CO2 hydrogenation.

Quantum mechanism of extremely high energy processes at neutron star collapse and of quasar luminosity

Using the braid group topological approach to quantum statistics we demonstrate that for strong gravitational field occurring in neutron star merger with mass exceeding the Tolman, Oppenheimer and Volkoff limit the quantum statistics of particles beneath the photon sphere decays, which results in an instant relief of quantum degeneracy pressure in the star. This causes a rapid shrink of the matter to a black hole with quite different quantum collective character of particles. The scheme of neutron Fermi sphere collapse is proposed as the possible isotropic source of short giant gamma-ray bursts. The similar quantum mechanism of collapse of Fermi spheres of electrons and protons in plasma of accretion disc in vicinity of the Schwarzschild horizon of galactic black hole is able to elucidate the giant luminosity of remote quasars. The efficiency of the mass to energy conversion via collapse of the Fermi sphere is ca. 30 %, not reachable for any other known physical process except of the matter-antimatter annihilation.

The breakdown of resummed perturbation theory at high energies

Calculations of high-energy processes involving the production of a large number of particles in weakly-coupled quantum field theories have previously signaled the need for novel non-perturbative behavior or even new physical phenomena. In some scenarios, already tree-level computations may enter the regime of large-order perturbation theory and therefore require a careful investigation. We demonstrate that in scalar quantum field theories with a unique global minimum, where suitably resummed perturbative expansions are expected to capture all relevant physical effects, perturbation theory may still suffer from severe shortcomings in the high-energy regime. As an example, we consider the computation of multiparticle threshold amplitudes of the form 1 → n in φ6 theory with a positive mass term, and show that they may violate unitarity of the quantum theory for large n, even after the resummation of all leading-n quantum corrections. We further argue that this is a generic feature of scalar field theories with higher-order self-interactions beyond φ4, thereby rendering the latter unique with respect to its high-energy behavior.

Cationic Curing of Epoxy–Aromatic Matrices for Advanced Composites: The Assets of Radiation Processing

Cross-linking polymerization of multifunctional aromatic monomers initiated by exposure to high energy radiation continues to be explored as a promising alternative to thermal curing for the production of high-performance composite materials. High-energy radiation processing offers several advantages over thermosetting technology by allowing for fast and out-of-autoclave curing operations and for its adaptability in the manufacturing of large and complex structures at reduced energy costs. The present article covers the basic aspects of radiation curing by cationic polymerization of epoxy resins, providing a status report on recent investigations conducted in our group to improve the properties of epoxy matrices and gain better control over the process for producing composites. A selection of results based on blends prepared with different composition of epoxy aromatics, transfer agents, thermoplastic toughening agents and onium salt initiators exemplifies the importance of the composition on polymerization kinetics and on the properties of resulting materials. The superiority of radiation-triggered polymerization-induced phase separation of thermoplastic additives is emphasized by the obtained morphology of toughened materials. The low initial temperature and fast curing of the reactive blends limits the expansion of phase-separated thermoplastic domains, resulting in an enhancement of the toughness.

Heterojunction and ferroelectric polarization co-promoting photocatalytic activity

The rapid recombination of photogenerated electrons and holes heavily restricts the photocatalytic efficiency. In this study, a polarized heterojunction photocatalyst g-C3N4/Bi2MoO6 (P-CNBMO) is prepared by high-energy ball-milling process and corona poling post-treatment. In comparison with pristine CN and BMO, all the heterojunctions demonstrate enhanced photocatalytic activity for degradation of tetracycline hydrochloride (TC). After introduction of corona poling, the photocatalytic performance of CNBMO is further increased. The considerably enhanced photocatalytic activity of P-CNBMO is attributed to the collective effect of formation of Type II heterojunction and ferroelectric polarization enhancement, which not only separate the photogenerated electrons and holes between CN and BMO, and also promote the charge separation in the bulk of BMO, as verified by the surface potential from Kelvin probe force microscope (KPFM) and photoelectrochemical measurements. This work is expected to provide referable instructions for the research on the cooperation of heterojunction and ferroelectric polarization for semiconductor photocatalysis.

Optimization of high-energy ball milling process for uniform p-type Bi-Sb-Te thermoelectric material powder

Optimization of high-energy ball milling process for uniform p-type Bi-Sb-Te thermoelectric material powder

Parton physics from a heavy-quark operator product expansion: Lattice QCD calculation of the second moment of the pion distribution amplitude

The pion light-cone distribution amplitude (LCDA) is a central non-perturbative object of interest for high-energy exclusive processes in quantum chromodynamics. In this article, the second Mellin moment of the pion LCDA is determined as a proof-of-concept calculation for the first numerical implementation of the heavy-quark operator product expansion (HOPE) method. The resulting value for the second Mellin moment, determined in quenched QCD at a pion mass of $m_\pi=550$ MeV at a factorization scale of 2 GeV is $ \langle \xi^2 \rangle = 0.210 \pm 0.013\text{ (stat.)} \pm 0.034\text{ (sys.)}$. This result is compatible with those from previous determinations of this quantity.

Neutron Star–Neutron Star and Neutron Star–Black Hole Mergers: Multiband Observations and Early Warnings

Abstract The detections of gravitational waves (GWs) from binary neutron star systems and neutron star–black hole systems provide new insights into dense matter properties in extreme conditions and associated high-energy astrophysical processes. However, currently, information about the neutron star equation of state (EoS) is extracted with very limited precision. Meanwhile, the fruitful results from the serendipitous discovery of the γ-ray burst alongside GW170817 show the necessity of early warning alerts. Accurate measurements of the matter effects and sky location could be achieved by joint GW detection from space and ground. In our work, based on two example cases, GW170817 and GW200105, we use the Fisher information matrix analysis to investigate the multiband synergy between the space-borne decihertz GW detectors and the ground-based Einstein Telescope (ET). We especially focus on the parameters pertaining to the spin-induced quadrupole moment, tidal deformability, and sky localization. We demonstrate that (i) only with the help of multiband observations we can constrain the quadrupole parameter; and (ii) with the inclusion of decihertz GW detectors, the errors of tidal deformability would be a few times smaller, indicating that many more EoSs could be excluded; (iii) with the inclusion of ET, the sky localization improves by about 1 order of magnitude. Furthermore, we have systematically compared the different limits from four planned decihertz detectors and adopting two widely used waveform models.

Photospheric Prompt Emission From Long Gamma Ray Burst Simulations. II. Spectropolarimetry

Abstract Although gamma ray bursts (GRBs) have been detected for many decades, the lack of knowledge regarding the radiation mechanism that produces the energetic flash of radiation, or prompt emission, from these events has prevented the full use of GRBs as probes of high-energy astrophysical processes. While there are multiple models that attempt to describe the prompt emission, each model can be tuned to account for observed GRB characteristics in the gamma and X-ray energy bands. One energy range that has not been fully explored for the purpose of prompt emission model comparison is that of the optical band, especially with regard to polarization. Here, we use an improved Monte Carlo radiation transfer code to calculate the expected photospheric optical and gamma-ray polarization signatures (Πopt and Π γ , respectively) from a set of two relativistic hydrodynamic long GRB simulations, which emulate a constant and variable jet. We find that time-resolved Πopt can be large (∼75%) while time-integrated Πopt can be smaller due to integration over the asymmetries in the GRB jet where optical photons originate; Π γ follows a similar evolution as Πopt with smaller polarization degrees. We also show that Πopt and Π γ agree well with observations in each energy range. Additionally, we make predictions for the expected polarization of GRBs based on their location within the Yonetoku relationship. While improvements can be made to our analyses and predictions, they exhibit the insight that global radiative transfer simulations of GRB jets can provide with respect to current and future observations.

Synthesis, air stability and electrochemical investigation of lithium superionic bromine substituted argyrodite (Li6-xPS5-xCl1.0Brx) for all-solid-state lithium batteries

The development of high ionic conducting solid electrolyte is one of the most active research topics in the field of lithium solid-state batteries. In the present study, we enhance the ionic conductivity of the lithium argyrodites using excess halogen substitution at the sulfur site. The halogen-rich Li6-xPS5-xCl1.0Brx (0 ≤ x ≤ 0.5) composition is synthesized through a high-energy ball milling process followed by heat treatment. The ionic conductivity measurement reveals that Li5.6PS4.6Cl1.0Br0.4 solid electrolyte exhibits a higher ionic conductivity value of 9.16 mS cm−1 than Li6PS5Cl (4.96 mS cm−1) at room temperature. The optimized electrolyte is utilized in a solid battery system thus shows a higher capacity of 188 mAh g−1 at 0.1C rate than Li6PS5Cl (181 mAh g−1). Interestingly, Li5.6PS4.6Cl1.0Br0.4 solid electrolyte maintains the higher capacity retention (80.6%) than the Li6PS5Cl (75.3%) after 50 cycles. Further, we demonstrate the influence of excess halogen substitution through electrochemical kinetics using electrochemical impedance spectroscopy and galvanostatic intermittent titration technique. Finally, the air stability test indicates that Li5.6PS4.6Cl1.0Br0.4 electrolyte delivers a high ionic conductivity of 5.26 mS cm−1 after 30 min dry air exposure.

Smaller Sized Hepatitis E Virus ORF2 Protein-Chitosan Nanoemulsion Conjugate Elicits Improved Immune Response

Comparative evaluation of immunomodulating efficiency of chitosan nanoemulsion and gold nanoparticles as an adjuvant for truncated HEV ORF2 structural proteins (26 kDa or 54 kDa) were analyzed. Hepatitis E virus (HEV) ORF2 structural protein has been reported to be immunogenic in nature. In the present study, we have used truncated forms of structural protein-containing C-terminus neutralization epitope as a vaccine candidate. A high-energy emulsification process synthesized chitosan nanoemulsions. HEV antigens were encapsulated in chitosan nanoemulsion (CNE26, CNE54). Swiss albino mice were immunized with these nanoconjugates, and their potency to stimulate humoral immune response as well as cell-mediated immune response was evaluated. The humoral response in mice immunized with CNE26 nanoconjugates was found to be 2.7 times that of IFA26 immunized group, while larger protein nanoconjugate (CNE54) and gold nanoconjugates displayed immune response comparable to that of IFA26 and IFA54. Furthermore, a slower rate of antibody formation was observed in the case of GNP26 immunized mice as compared to GNP54 ones, emphasizing the effect of the size of nanomaterials/nanoconjugates on the immune response. At the same time, the effect of surface functionalization and inherent immune modulation property of chitosan nanoemulsion was observed for CNE nanoconjugates. Both gold and chitosan nanoconjugates elicited cell-mediated immune response as well in mice. This study suggests that smaller-sized protein antigen-chitosan nanoemulsion conjugate has higher immunological potential and can be a better future vaccine candidate than gold nanoparticles.

In situ formed ultrafine metallic Ni from nickel (II) acetylacetonate precursor to realize an exceptional hydrogen storage performance of MgH2[sbnd]Ni-EG nanocomposite

It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH2. However, so far it is still a challenge to directly synthesize ultrafine catalysts (e.g., < 5 nm), mainly because of the complicated chemical reaction processes. Here, a facile one-step high-energy ball milling process is developed to in situ form ultrafine Ni nanoparticles from the nickel acetylacetonate precursor in the MgH2 matrix. With the combined action of ultrafine metallic Ni and expanded graphite (EG), the formed MgH2Ni-EG nanocomposite with the optimized doping amounts of Ni and EG can still release 7.03 wt.% H2 within 8.5 min at 300 °C after 10 cycles. At a temperature close to room temperature (50 °C), it can also absorb 2.42 wt.% H2 within 1 h. It can be confirmed from the microstructural characterization analysis that the in situ formed ultrafine metallic Ni is transformed into Mg2Ni/Mg2NiH4 in the subsequent hydrogen absorption and desorption cycles. It is calculated that the dehydrogenation activation energy of the MgH2Ni-EG nanocomposite is also reduced obviously in comparison with the pure MgH2. Our work provides a methodology to significantly improve the hydrogen storage performance of MgH2 by combining the in situ formed and uniformly dispersed ultrafine metallic catalyst from the precursor and EG.

Influence of Natural Processes and Bottom Trawling in the Nepheloid Layer Structure Off Vancouver Island (British Columbia, Canada, NE Pacific)

Continental margins are transitional areas between the land and the deep ocean where large amounts of particulate matter are supplied, transported, and ultimately deposited in the deep sea. High-energy hydrodynamic processes such as storms, ocean currents, or internal waves and tides, as well as bottom trawling activities contribute to the resuspension and remobilization of these particles. These mechanisms favor their transference from the continental shelf to the continental slope and maintain high concentrations of particulate matter in the water column forming nepheloid layers. The temporal evolution of the hydrographic and nepheloid structure in the upper slope off Vancouver Island (British Columbia, Canada, NE Pacific) was assessed by analyzing 4 months (from mid-August to late-November 2018) of sensor data from Ocean Networks Canada (ONC) NEPTUNE cabled seafloor observatory. The distribution of particulate matter during the study period illustrated a well-defined turbidity structure consisting of surface nepheloid layers (SNLs) at &amp;lt;100 m depth associated to primary and secondary productivity, intermediate nepheloid layers (INLs) between 150 and 300 m depth at the shelf-break and upper slope domain, and bottom nepheloid layers (BNLs) developed at &amp;gt;400 m depth. Moderate storm events occurred during fall when the more intense INLs were recorded at shelf-break depths. However, not all the INLs recorded during this period occurred in coincidence with these storms, indicating that these INL detachments were modulated by a different sediment resuspension mechanism. Analyses of fishing vessel activity during the study period revealed that trawlers operated over the same depth range as these INLs. Our results suggest that, in combination with the regional currents, the presence of continuous fishing along the continental slope off Vancouver Island contributes to the advection of suspended sediment particles, playing a major role in their transfer as nepheloid layers.

Investigation of the third-order optical nonlinearity of Au/GO-CeO2 nanocomposites under different high-energy ball milling parameters

A high-energy ball milling process along with the hydrothermal method was applied to synthesize Au/GO-CeO2 nanocomposites. X-ray diffraction analysis and FT-IR spectroscopy confirmed the successful synthesis of nanocomposites. The ball milling parameters dependence of the nonlinear optical response of Au/GO-CeO2 nanocomposites was investigated by using the Z-scan measurements under pulsed Nd: YAG laser irradiation at 532 nm. The measurements showed that Au/GO-CeO2 nanocomposites have negative nonlinearity which can be controlled by ball milling parameters to achieve higher values for third-order nonlinear optical susceptibility of the order of 10−8 esu. The investigations showed that ball milling parameters such as ball milled time and the number of hardened zirconia oxide balls are important factors in the resultant nonlinear optical parameters. The results suggest that Au/GO-CeO2 nanocomposites with a strong nonlinear optical response can be a promising nonlinear medium that can open a new avenue to graphene-based nonlinear optics.

Structural properties of chalcogenides nanostructures

Following the discovery of carbon fullerenes and nanotubes (NTs), nanostructured materials and their synthesis have attracted tremendous attention due to their superior mechanical properties, their unique electronic behavior, and their high potential in making technologically advanced nanodevices. Among different classes, layered metal chalcogenides nanostructures are of interest for a variety of applications ranging from nanoelectronics or as source materials for energy applications, nanotribology and in heterogeneous catalysis. These nanoparticles are metastable phases. Therefore, equilibrium methods are necessary to prevent the formation of the thermodynamically stable bulk phase. On the other hand, high energies are needed to “knit” together the folded layers. Several physical techniques such as laser ablation and arch discharge are used for the synthesis of these inorganic NTs and fullerene-like particles. Apart from these high-energy techniques other processes such as oxide-to-sulfide conversion, hydrothermal, solvothermal, or wet chemical synthesis were found to be useful for the synthesis of these particles.

Phenomenology of a Born-Infeld extension of the U(1)Y sector at lepton colliders

In this work we perform a non-linear extension of the $U(1)_{\rm Y}$ sector of the Standard Model leading to novel quartic effective interactions between the neutral gauge bosons. We study the induced effects through high-energy processes resulting in three photons, namely, Z-boson decay and electron-positron annihilation. Available experimental data on these processes do not yield viable lower bounds on the mass parameter $\sqrt{\beta}$, but we estimate that the range $\sqrt{\beta} \lesssim m_Z$ could be reliably excluded with better statistics in future $e^- e^+$ colliders. We also discuss neutral gauge-boson scatterings, contextualizing our findings with recent results on anomalous quartic gauge couplings.

Tailoring alloy 718 laser directed energy deposition process strategies for repair applications

Laser-based directed energy deposition (LDED) for repair and sustainment has become a viable alternative to replace or complement traditional repair applications. Many a time, thin-walled structures cannot be repaired because of the heat intensive repair operations, which lead to excessive distortion or degradation of the parent material. To overcome repair challenges related to thin-walled structures, a low-energy process strategy with powder feedstock has been developed to reduce the heat-affected zone, reduce distortion, and produce a microstructure yielding higher microhardness values. On the other side of the repair spectrum, much larger surfaces may also need attention. In this case, a high-deposition rate process strategy may be more suitable to reduce lead-time and cost. To accommodate larger repairs, a high-deposition rate process strategy using wire feedstock has been developed. The high-deposition rate strategy is shown to be more cost-effective provided the target application and part geometry can accommodate the high-energy process. Validating these LDED repair strategies has been accomplished by analyzing the resulting distortion, presence of flaws or defects, microhardness, microstructure, and tensile properties. The process control offered by LDED through the ability to tailor the process-structure-property relationships of a material system depending on component geometry and application has put a new tool in place addressing many concerns related to traditional arc-based repair processes.

Effect of Magnesium Addition and High Energy Processing on the Degradation Behavior of Iron Powder in Modified Hanks’ Solution for Bioabsorbable Implant Applications

This paper shows the results of applying a combination of high energy processing and magnesium (Mg) as an alloying element in a strategy for enhancing the degradation rate of iron (Fe) for applications in the field of non-permanent medical implants. For this purpose, Fe powder was milled with 5 wt% of Mg (Fe5Mg) and its microstructure and characterized degradation behavior. As-received Fe powder was also milled in order to distinguish between the effects due to high energy processing from those due to the presence of Mg. The powders were prepared by high energy planetary ball milling for 16 h. The results show that the initial crystallite size diminishes from &gt;150 nm to 16 nm for Fe and 46 nm for Fe5Mg. Static degradation tests of loose powder particles were performed in Hanks’ solution. Visual inspection of the immersed powders and the X-ray diffraction (XRD) phase quantification indicate that Fe5Mg exhibited the highest degradation rate followed by milled Fe and as received Fe, in this order. The analysis of degradation products of Fe5Mg showed that they consist on magnesium ferrite and pyroaurite, which are known to present good biocompatibility and low toxicity. Differences in structural features and degradation behaviors of milled Fe and milled Fe5Mg suggest the effective dissolution of Mg in the Fe lattice. Based on the obtained results, it can be said that Fe5Mg powder would be a suitable candidate for non-permanent medical implants with a higher degradation rate than Fe.