Electron Energy Research Articles

Experimental Study on the Impact of Sulfate Attack on the Performance of Shaft Lining Concrete under Sustained Compressive Load

To investigate the impact of sulfate corrosion on the performance of shaft lining concrete under sustained compressive loads, this study immersed samples in a 10% sodium sulfate solution after subjecting to sustained compressive loads of 0.2fcand 0.4fc. The variation in compressive strength, ultrasonic velocity, and dynamic elasticity modulus with corrosion age were examined. The corrosion mechanisms were analyzed using field emission scanning electron microscope and energy dispersive spectrometer. The impact tendency of concrete was also evaluated. The results indicated that under sustained compressive loads of 0.2fcand 0.4fc, the compressive strength, ultrasonic velocity, and dynamic elasticity modulus are all increased with age, in the order of 0.2fc> 0.4fc>no-load. When exposed to a 10% sodium sulfate solution under sustained compressive loads, these properties initially increased and then decreased, peaking at 90 days of corrosion age, and the order was 0.2fc> no-load > 0.4fc when the corrosion age was longer than 240 days.The shaft lining concrete exhibited weak impact tendency, with the brittleness index increasing as the corrosion age progressed. The outcome of this work might provide a reference for the further research on the design of shaft lining concrete materials.

Copper doped hybrid 2D ZnO-stearic acid nanocomposite for boosting photocatalytic degradation of organic pollutants under simulated solar light

This study explores the enhancement of photocatalytic performance in 2D ZnO-stearic acid (SA) composites through copper (II) doping. Materials containing 1–10 mol% Cu (II) were synthesized by coprecipitation and characterized using X-ray photoelectron spectroscopy, electron paramagnetic resonance, UV–visible and vibrational spectroscopies, as well as X-ray diffraction. These analyses confirmed the formation of single-phase composites with structures resembling the ZnO-SA precursor, but exhibiting discrete Zn/Cu doping, forming Zn1-xCuOx-SA materials. Scanning electron microscopy and Energy dispersive X-ray spectroscopy analysis revealed layered structure and the elemental compositions of the samples. High-resolution transmission electron microscopy (HR-TEM) images confirm the layered morphology of the Zn0.95Cu0.05O-SA sample, underscoring its two-dimensional material characteristics. Absorption band edge of the undoped hybrid ZnO is centered in the UVA zone, while copper-doped samples expanded into the visible range. Photoluminescence (PL) spectra exhibit multiple emission peaks related to defects within ZnO host. An intensity slight decrease in PL intensity is observed with increasing copper concentration, indicated a low recombination rate. Photoelectrochemical testing showed that Cu doping reduces charge recombination and increases current density, thereby improving photocatalytic degradation of pollutants such as indigo carmine and 4-chlorophenol under simulated sunlight. The optimally doped Zn0.95Cu0.05O-SA displayed significant efficiency improvements, degrading contaminants up to four times faster than the undoped composite and maintaining consistent performance over multiple cycles. Additional testing linked these photocatalytic improvements to enhanced charge separation and electron/hole transfer facilitated by Cu2+ ions, thereby boosting photocatalytic activity.

Divalent manganese (Mn2+, 3d5) charge transfer energies and vacuum-referred binding energies in inorganic compounds

Ongoing efforts to develop a predictive model governing the host-referred binding energies (HRBEs) and vacuum-referred binding energies (VRBEs) of transition metal dopants in inorganic host compounds are stymied by a lack of cross-compound data sets that capture transitions between the dopant ions and the valence and conduction bands of the hosts. Herein, we have compiled data consistent with Mn2+ charge transfer processes in 53 different compounds, spanning fluorides, oxides, chlorides, bromides, and nitrides. By assigning these transitions to Mn2+ → conduction band metal-to-metal charge transfer and combining these energies with the binding energies of electrons in the valence and conduction bands of the various hosts, we have calculated the HRBEs and VRBEs of the Mn2+ ion across a range of compounds. We show that variations in the Mn2+ VRBE are small relative to the variations in the VRBE of the valence and conduction bands, which manifests an approximately linear relationship between the Mn2+ HRBE and the bandgap energy of host compounds. We investigated the relationship between the Mn2+ VRBE and the various structures of the host compounds and showed that the chemical shift experienced by the Mn2+ ion depends on the electronegativity of the ligand, the Mn2+ coordination, and the Mn-ligand bond lengths in a predictable manner.

Multiwavelength Observations of Sgr A*. II. 2019 July 21 and 26

We report on the final two days of a multiwavelength campaign of Sgr A* observing in the radio, submillimeter, infrared (IR), and X-ray bands in 2019 July. Sgr A* was remarkably active, showing multiple flaring events across the electromagnetic spectrum. We detect a transient ∼35 minute periodicity feature in Spitzer light curves on 2019 July 21. Time-delayed emission was detected in Atacama Large Millimeter/submillimeter Array light curves, suggesting a hotspot within the accretion flow on a stable orbit. On the same night, we observe a decreased flux in the submillimeter light curve following an X-ray flare detected by Chandra, and we model the feature with an adiabatically expanding synchrotron hotspot occulting the accretion flow. The event is produced by a plasma 0.55 R S in radius with an electron spectrum p = 2.84. It is threaded by a ∼130 Gauss magnetic field and expands at 0.6% the speed of light. Finally, we reveal an unambiguous flare in the IR, submillimeter, and radio, demonstrating that the variable emission is intrinsically linked. We jointly fit the radio and submillimeter light curves using an adiabatically expanding synchrotron hotspot and find it is produced by a plasma with an electron spectrum p = 0.59, 187 Gauss magnetic field, and radius 0.47 R S that expands at 0.029c. In both cases, the uncertainty in the appropriate lower and upper electron energy bounds may inflate the derived equipartition field strengths by a factor of 2 or more. Our results confirm that both synchrotron- and adiabatic-cooling processes are involved in the variable emission’s evolution at submillimeter and IR wavelengths.

A mechanical TiAl/TiAlN multinanolayer coating model based on microstructural analysis and nanoindentation

A finite element model reproducing the mechanical behaviour during nanoindentation tests on Ti0.67Al0.33/Ti0.54Al0.46N multilayer coatings was developed. Coatings with two different nanoperiods (10 and 50 nm) were deposited by radio-frequency magnetron sputtering from a single sintered titanium/aluminium target using the reactive gas pulsing process. X-ray diffraction and transmission electron microscopy confirmed the multilayer stacking of the coatings. The finite element models of coatings with these two stacking periods were built considering successive hypotheses: equal thicknesses for metal and nitride nanolayers stacked without transition layer, equal thicknesses stacking with a transition layer between each metal and nitride nanolayer and finally imbalanced thicknesses stacking with a transition layer. The elastic and plastic properties of the stacked nanolayers were determined on thick monolithic coatings of metal and nitride using indentation testing and the finite element model updating method respectively. The elastic-plastic properties of the interface were introduced in the multilayer model as a rule of mixtures of the metal and nitride properties using two hypotheses: parallel or serial. For 50 nm-period film, the interface has a negligible effect on the overall indentation response. On the other hand, for the 10 nm period, the imbalanced stacking model with precise knowledge of the transition layer thickness obtained by N K-edge electron energy loss spectroscopy is required to reproduce the experimental indentation curve. Compared to classical analytical models accounting for hardness, not only the hardnesses but also the indentation moduli appear to be well predicted and evaluated in this work.

A DFT study of the CaMg2As2 material for photovoltaic applications

The research focused on investigating the structural, elastic, electronic, optical, and thermoelectric characteristics of the CaMg2As2 compound. To inspect these properties, the density functional theory (DFT) method has been applied via the Wien2K code. The electronic analysis revealed that the CaMg2As2 compound demonstrates semiconductor behavior with an indirect band gap of 1.781 eV. Additionally, its elastic properties were examined, revealing a 1.980 % AVR, indicating a variation in elasticity depending on the direction of load or stress applied. We have also studied various optical properties of CaMg2As2, including the refractive index, extinction coefficient, electron energy loss, dielectric tensor, and optical conductivity. the absorption coefficient value is zero for energy levels below 2.60 eV, meaning there is no energy absorption by the material at lower energy levels. However, as the energy surpasses 2.60 eV, the absorption coefficient increases and shows multiple peaks. This signifies that as the incident radiation's energy increases, the material starts absorbing more energy at specific energy levels. In addition, one significant finding is that the thermal conductivity of the lattice (κL) in CaMg2As2 decreases exponentially as the temperature rises. This means that as the material gets hotter, its ability to conduct heat becomes less effective. In simple terms, the material becomes less efficient at transferring heat at higher temperatures. These findings suggest that CaMg2As2 has potential as a thermoelectric material with interesting properties that deserve further investigation.

Spectroscopic analysis of color origins in titanium-based thin films deposited by cathodic arc deposition

The distinctive colors observed in titanium-based (Ti-based) decorative coatings fabricated by cathodic arc deposition originate from the unique electronic, morphological, and chemical properties of these films. Most Ti-based film colors arise from their surface band gaps, as measured by electron energy loss spectroscopy, with the exception of the lowest brightness (TLB) and green hues. The green color in titanium dioxide films typically results from interference between light reflected from the film and substrate interfaces. In contrast, the black color in Ti-based coatings stems from the chemical structure, specifically the presence of Ti-C and C=C(sp2) bonds within the film. Moreover, the large band gap of the LTB film surface is attributed to surface oxidation, as detected by soft X-ray spectroscopy. Significantly, the film thickness and surface roughness are characterized by field emission secondary electron microscopy and atomic force microscopy, respectively.

Enhanced secondary electron emission properties of sputter-deposited MgO–Au composite film via Cr doping

High and stable secondary electron emission yield (SEY) is essential for thin film materials used for electrical signal amplification in electronic devices. To enhance the secondary electron emission (SEE) capability of MgO–Au composite film, Cr-doped MgO–Au film was prepared by magnetron sputtering and the effect of Cr doping on the SEE properties of MgO–Au film was intensively investigated. It was confirmed that the doped Cr element is distributed through the whole composite film in a form of Cr2O3. Compared to the conventional MgO–Au film, the Cr-doped MgO–Au film with a Cr/(Cr + Mg) atomic ratio of 0.71 % achieves a SEY of 7.1 with a 4.4 % rise at the primary electron energy (Ep) of 300 eV and a maximum SEY of 10.9 with a 10.1 % increase at the Ep of 800 eV, and it also has a reduction of 49.2 % in SEE decay rate under continuous electron bombardment. For this novel composite film, the SEY ascension mainly attributes to the MgO grain enlargement and chemical stability enhancement, and the decreased SEE decay rate is associated with the improvements of resistance to electron bombardment and electric conductivity induced by Cr doping.

Effects of sputtering pressure on microstructure and secondary electron emission properties of AlN film prepared by magnetron sputtering

In this paper, aluminum nitride (AlN) thin films were prepared by reactive radio-frequency magnetron sputtering at different sputtering pressures and the crystalline structure, surface morphology and secondary electron emission (SEE) properties of the AlN films were studied in detail. The experimental results reveal that AlN films present the preferred orientation of a-axis (100), and the grain size and surface roughness of the film decrease with the increase of sputtering pressure. Additionally, the SEE coefficient of the film reaches a maximum of 4.3 at 200 eV when the sputtering pressure is 0.55 Pa and is relatively stable under the continuous bombardment of an incident electron with the energy of 200 eV. Thus, the AlN thin film prepared under the optimized sputtering pressure has a relatively high and stable coefficient at a low incident electron energy, which promotes its potential application in the high-gain and long-life electron multipliers.

Improving energy harvesting through femtosecond laser surface modification of PVDF/ZnS composite nanofibrous nanogenerators for electronic applications

Surface modification in ceramic/polymer composites holds paramount importance for electronic devices applications. Laser is a versatile and flexible device for modifying the surface characteristics of various materials. Here, we propose a novel approach to enhance the energy harvesting efficiency of polyvinylidene fluoride (PVDF) and zinc sulfide (ZnS) composite nanofibrous membranes through femtosecond laser surface modification. The electrospinning technique is used to produce nanofibers with a high β-phase content in a single step. The PVDF membrane was further enriched with ZnS nanoparticles to enhance the β-phase content. The membranes were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Electron Energy Loss spectroscopy (EELS), and Fourier-transform infrared spectroscopy (FTIR) to characterize their morphological and chemical properties. Femtosecond laser was employed to induce controlled surface modifications, resulting in hierarchical microstructures and surface functionalization. The results showed patterned tracks on the fiber surface while preserving its inherent nature. To validate its utility as an energy harvesting device, the membrane's capability was assessed by measuring the open circuit voltage. The results revealing average output voltages for nanogenerators treated with laser fluences of 0.5 J/cm2, 0.7 J/cm2, and 0.9 J/cm2 are 15.6 V, 25 V, and 17 V, respectively. The maximum output voltage is observed for a laser fluence of 0.7 J/cm2, attributed to the deeper structure created, increasing the surface area of contact and deformation in the structure. This work offers promising avenues for enhancing energy harvesting efficiency and expanding the scope of electronic devices such as sensors and actuators.

Heating mode transitions in capacitively coupled CF4 plasmas at low pressure

Abstract Capacitively coupled plasmas operated in CF4 at low pressure are frequently used for dielectric plasma etching. For such applications the generation of different ion and neutral radical species by energy dependent electron impact ionization and dissociation of the neutral background gas is important. These processes are largely determined by the space and time dependent electron energy distribution function and, thus, by the electron power absorption dynamics. In this work and based on a particle-in-cell/Monte Carlo collision model, we show that the electron heating mode in such plasmas is sensitive to changes of the gap at a constant pressure of 3 Pa. At a gap of 1.5 cm, the dominant mode is found to be a hybrid combination of the Drift-Ambipolar (DA) and the α-mode. As the gap is increased to 2 cm and 2.5 cm, the bulk power absorption and ambipolar power absorption decreases, and the DA mode decays. When the gap reaches 3 cm, the α-mode becomes more prominent, and at a gap of 3.75 cm the α-mode is dominant. These mode transitions are caused by a change of the electronegativity and are found to affect the discharge characteristics. The presence of the DA-mode leads to significant positive electron power absorption inside the bulk region and negative power absorption within the sheaths on time average, as electrons are accelerated from the bulk towards the collapsed sheath. The heating mode transitions result in a change from negative to positive total electron power absorption within the sheaths as the gap increases. When accounting for secondary electron emission, the transition of the heating mode can occur at shorter gaps due to the enhanced plasma density and decreased electronegativity.

Reduction in mycotoxin levels of African nutmeg (Monodora myristica) powder using a high-energy electron beam

This study investigated the role of irradiation with a high-energy electron beam in reducing mycotoxin levels of African nutmeg powder (ANP) samples. African nutmeg was procured from a local market in Accra, Ghana, cleaned, milled, packaged and irradiated using electrons of energy 9 MeV at doses of 2, 4, 6 and 8 kGy. Un-irradiated ANP served as a control. Mycotoxin levels of the treated samples were determined using appropriate standard methods. Aflatoxins B1 (AFB1) and B2 (AFB2) as well as ochratoxin A (OTA) were detected in the nutmeg samples. Irradiation significantly (p < 0.05) reduced mycotoxin levels of the ANP with increasing doses. Aflatoxins G1 and G2 were not detected in any of the samples. A dose of 8 kGy was effective in reducing the mycotoxin levels below the permissible limit in food. This suggests that a high-energy electron beam is effective in reducing mycotoxin levels in African nutmeg powder.

Effect of Rice Husk Ash (RHA) and slake-lime as partial replacement of cement in the production of concrete

This study examines the utilization of rice husk ash (RHA) and slaked lime as substitutes for a portion of the cement in manufacturing concrete. The RHA was acquired from a nearby source, subjected to calcination at temperatures ranging from 500 to 700 °C, and then passed through a sieve to obtain particles with a size of 150 microns. Concrete mixes were made using Ordinary Portland cement (OPC), fine and coarse aggregates, and water, with different amounts of RHA and slaked lime. The concrete mix design adhered to established standards, with a mix ratio of 1:1.5:3 (cement: fine aggregate: coarse aggregate). The experiment was designed using response surface methods, with RHA, slaked lime, and cement as factors, each having five levels. Concrete cubes were formed using 100 mm steel moulds and then submerged in water to assess their workability. The compressive strength was measured using universal testing equipment after 7, 28, and 90 days of cure. The flexural strength of concrete beams was assessed after 7 and 28 days. Samples were subjected to scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) examination after 28 days. The compressive and flexural strengths increased as the curing period progressed, with the 10% RHA substitution showing the maximum strength. The SEM analysis showed that RHA10 exhibited the maximum concentration of silicon, which corresponds to the recommended 10% replacement level of OPC and meets the concrete specifications specified by ASTM M20 grade. Utilising RHA decreases expenses and minimises the amount of concrete that is discarded. The most effective replacement for OPC was 10% RHA, which produced long-lasting and strong concrete.

Magnetic field and dielectric beads modulate DBD reduced electric field with discharge homogeneity to realize NOx differential conversion

In this paper, the reduced electric field and the discharge homogeneity of DBD were modulated by the magnetic field and the packed ZrO2 beads. Subsequently, the reduced electric field and the discharge homogeneity on discharge performance, de-NOx efficiency and NOx conversion mechanism were evaluated. The experimental results show that the reduced electric field gradually enhances as the magnetic field increases, promoting de-NOx performance. The discharge homogeneity significantly weakens with the length of packed ZrO2 beads increases, inhibiting the de-NOx performance. Compared to the reactor with the packed ZrO2 beads, the de-NOx efficiency of the reactor with a 0.2 T magnetic field can achieve 87.2 %, an improvement of 39.3 %. Meanwhile, the selectivity of NO2 and N2O are reduced by 18.3 % and 21 %, respectively. The de-NOx mechanisms indicate that the reduced electric field affects the electron collision reactions and the relative rate of the NOx conversion reactions by altering the electron energy distribution. The discharge homogeneity alters the degree of plasma mitigation of exhaust gases by regulating the absolute rate of the NOx conversion reactions. The by-product N2O is mainly dependent on the concentration of NO2 and is less sensitive to N2(A3). This work reveals the differential mechanisms of reduced electric field and discharge homogeneity on de-NOx.

Quantitative time-resolved diagnostics of electric field dynamics during individual plasma breakdown events using burst laser pulse electric field induced second harmonic generation

In plasma discharges, the acceleration of electrons by a fast varying electric field and the subsequent collisional electron energy transfer determines the plasma dynamics, chemical reactivity, and breakdown. Current in situ electric field measurements require reconstruction of the temporal profile over many observations. However, such methods are unsuitable for non-repetitive and unstable plasmas. Here, we present a method for creating “movies” of dynamic electric fields in a single acquisition at sample rates of 500 × 106 fps. This ultrafast diagnostic was demonstrated in radio frequency electric fields between two parallel plates in air, as well as in Ar nanosecond-pulsed single-sided dielectric barrier discharges.

Remarkable enhancement of the nonlinear optical behavior towards asymmetric substituted D-π-A dithiophene-based compounds.

Nonlinear optics (NLO) is an interesting field that discloses the interaction between intense light and matter, leading to a deeper understanding of NLO phenomena. Organic chromophores are considered as promising materials for NLO due to their exceptional structural versatility, ease of processing, and rapid response to NLO effects. Functional materials based on thiophene have been indispensable in advancing organic optoelectronics. Specifically, dithiophene-based compounds display weaker aromaticity, reduced steric hindrance, and additional sulfur-sulfur interactions. Hence, by utilizing dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene (DTBDT) as the core structure, designing of a set of organic compounds with D1-π-D2-π-A-type framework, namely ZR1D1-ZR1D8, was carried out in this study. The analysis of frontier molecular orbitals (FMOs) revealed that compound ZR1D2 has the lowest band gap of 1.922eV among all the investigated chromophores. The correlation of global reactivity parameters (GRPs) with the band gap values indicates that ZR1D2 displays a hardness of 0.961eV and a softness of 0.520eV-1. Among the studied compounds, ZR1D2 demonstrated a broad absorption spectrum that extended across the visible region. The maximum absorption wavelengths were observed at 766.470nm for ZR1D2 and 749.783nm for ZR1D5. These DTBDT-based dyes exhibit a remarkable NLO response with exceptionally high first hyperpolarizability (βtot) values. Among them, compound ZR1D2 stands out with the highest average linear polarizability (⟨α⟩ = 3.0 × 10-22 esu), first hyperpolarizability (βtot = 4.1 × 10-27 esu), and second hyperpolarizability (γtot = 7.5 × 10-32 esu) values. In summary, this investigation offers valuable insights into the potential use of DTBDT-based organic chromophores, particularly ZR1D2, for advanced applications in NLO. These findings suggest promising opportunities for researchers to synthesize these molecules and utilize these compounds in hi-tech NLO-based applications. The density functional theory computations were performed at the M06/6-311G(d,p) functional to explore their structural effects on electronic and NLO findings. Various analyses like highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps, absorption maxima, density of states, open circuit voltage, binding energies of electrons and holes, and transition density matrix are employed to investigate photovoltaic efficiencies of the derivatives. Different software packages like Avogadro, Multiwfn, Origin, GaussSum, PyMOlyze, and Chemcraft were used to deduce conclusions from the output files.

Ecotoxicological assessment of nano-remediated crude oil contaminated soil using Zea mays

The germination of seedlings is hindered in soil due to the excessive presence of petroleum hydrocarbons resulting from crude oil spill. This contamination not only pollutes the environment but also renders it unsuitable for habitation, inhibits animal grazing, and results in the degradation of natural beauty and aesthetic appeal. In this work, the ecotoxicological effect of nanoremediated soil previously contaminated with crude oil was assessed. Petroleum hydrocarbons were eliminated from crude oil contaminated soil through the utilization of nanomaterial adsorbents namely: Multiwalled Carbon Nanotubes (MWCNTs), MWCNTs + IONP (Iron Oxide Nanoparticle), and P.N.C (Polymer Nanocomposite) followed by the cultivation of Zea mays seedling on the nanoremediated soils then observed over a period of seven days. Both the contaminated and treated samples were evaluated for their respective functional groups, structural morphology and elemental compositions using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Fluorescence (ED XRF) techniques. The seedlings were then harvested, and the lengths of their leaves, shoots, and roots were measured and recorded. Results indicated a germination rate of over 70 % achieved for seedlings cultivated in the nanoremediated soils, in contrast to a germination rate of only 40 % for seedlings grown in untreated crude oil contaminated soil. Seedlings from the soil treated with P.N.C exhibited the most favorable growth parameters, with leaf, shoot, and root lengths measuring 7.64, 4.83, and 8.04 cm respectively. In comparison, seedlings germinated in crude oil contaminated soil displayed measurements of 3.4, 2.79, and 5.32 cm for leaf, shoot, and root lengths, respectively. The pH levels of the treated soils were raised from 5.7 to 6.9, 6.3, and 6.7 for MWCNTs only, MWCNTs + IONP, and P.N.C, respectively. This augmentation had a positive impact on the uptake of nutrients through the root hairs. Additionally, it was noted that the presence of MWCNTs did not impede the germination and growth of Zea mays seedlings. This technique exhibits considerable potential for widespread adoption by farmers, oil companies, and environmental agencies as a rapid and effective nano-remediation method.

Influence of annealing temperature on the structure, morphology, optical property and antibacterial response of phytochemicals-assisted synthesized zinc oxide nanoparticles

Abstract Antibiotic overuse has caused a variety of bacterial pathogens to develop new resistance mechanisms. As a result, discovering an appropriate replacement for the standard antibiotics has become an immediate concern. The present work demonstrates a facile, eco-friendly and economical method for the synthesis of hexagonal wurtzite zinc oxide nanoparticles (ω-ZONPs) using the ethanolic extract of triphala. Gas chromatography–mass spectrometry analysis of the triphala extract proved the presence of certain secondary metabolites, which aids in the formation of ω-ZONPs. The influence of annealing temperature on the antibacterial action of as-synthesized ω-ZONPs was studied for three different annealing temperatures. X-ray diffraction, dynamic light scattering, field emission electron microscopy and energy dispersive X-ray spectroscopy analyses were used to examine the impact of annealing temperature on the structure, particle size and morphology of ω-ZONPs. Fourier transform infrared spectra revealed the change in intensity of the characteristic peaks in ω-ZONPs with different annealing temperatures. From UV–Visible diffuse reflectance spectroscopy, variation in the band gap of ω-ZONPs with increasing annealing temperature was detected. Kirby Bauer disc diffusion was adopted to examine the antibacterial potential of ω-ZONPs against bacterial strains such as Staphylococcus aureus, Enterococcus faecium, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. The ω-ZONPs annealed at 200 °C inhibited the growth of three bacterial pathogens, E. coli, B. subtilis and P. aeruginosa and exhibited effective antibacterial activity in comparison with ω-ZONPs annealed at relatively high temperatures. Thus, the antibacterial potential of ω-ZONPs could be further explored as disease controlling agents and such prototypes could be made available for commercial mass production.

Preparation of CNT/diamond composite via MPCVD: The interface behavior

Carbon nanotubes (CNTs) and diamonds are allotropes of carbon, exhibiting excellent thermal, mechanical, optical, and electrical properties. Integrating CNTs with diamonds could advance the thermal management of high-heat-flux devices, light absorption, and novel semiconductor devices. This study reports the synthesis of vertical CNTs on a diamond substrate using microwave plasma chemical vapor deposition (MPCVD). Enhanced interfacial adhesion between the CNTs and diamond was confirmed by subjecting the CNT/diamond composite to ultrasonic vibrations and analyzing the morphology via scanning electron microscopy. The growth mechanism of CNTs on the diamond and the CNT/diamond interface bonding behavior were investigated using scanning transmission electron microscopy, electron energy loss spectroscopy, energy-dispersive X-ray spectroscopy, and optical emission spectroscopy. The results indicate that the carbon supplied from two different sources drove the growth of CNTs primarily through the root-growth mechanism and, to a lesser extent, through the tip-growth mechanism. The tip-growth mechanism may involve the formation of a covalent connection at the CNT/diamond interface. For the root-growth mechanism, two interfaces emerged in the CNT/diamond composite, namely Fe/diamond and CNT/Fe. Additionally, mixed cementite phases connected the CNTs to the diamond substrate. Elucidating the bonding mechanism between the CNTs and diamond can provide insights into the dynamics of the carbon atoms in the catalyst and offer a deeper understanding of the growth mechanism of CNTs on the diamond substrate.

Multifrequency Analysis of Favored Models for the Messier 87* Accretion Flow

The polarized images of the supermassive black hole Messier 87* (M87*) produced by the Event Horizon Telescope (EHT) provide a direct view of the near-horizon emission from a black hole accretion and jet system. The EHT theoretical analysis of the polarized M87* images compared thousands of snapshots from numerical models with a variety of spins, magnetization states, viewing inclinations, and electron energy distributions, and found a small subset consistent with the observed image. In this article, we examine two models favored by EHT analyses: a magnetically arrested disk with moderate retrograde spin and a magnetically arrested disk with high prograde spin. Both have electron distribution functions that lead to strong depolarization by cold electrons. We ray trace five snapshots from each model at 22, 43, 86, 230, 345, and 690 GHz to forecast future very long baseline interferometry (VLBI) observations and examine limitations in numerical models. We find that even at low frequencies where optical and Faraday rotation depths are large, approximately rotationally symmetric polarization persists, suggesting that shallow depths dominate the polarization signal. However, morphology and spectra suggest that the assumed thermal electron distribution is not adequate to describe emission from the jet. We find 86 GHz images show a ringlike shape determined by a combination of plasma and spacetime imprints, smaller in diameter than recent results from the Global mm-VLBI Array. We find that the photon ring becomes more apparent with increasing frequency, and is more apparent in the retrograde model, leading to large differences between models in asymmetry and polarization structure.