The electronic structures of two-dimensional materials are strongly dependent on their thicknesses; for example, there is an indirect to direct band gap transition from multilayer to single-layer ...MoS2. A simple, efficient, and nondestructive way to control the thickness of MoS2 is highly desirable for the study of thickness-dependent properties as well as for applications. Here, we present layer-by-layer thinning of MoS2 nanosheets down to monolayer by using Ar+ plasma. Atomic force microscopy, high-resolution transmission electron microscopy, optical contrast, Raman, and photoluminescence spectra suggest that the top layer MoS2 is totally removed by plasma while the bottom layer remains almost unaffected. The evolution of Raman and photoluminescence spectra of MoS2 with thickness change is also investigated. Finally, we demonstrate that this method can be used to prepare two-dimensional heterostructures with periodical single-layer and bilayer MoS2. The plasma thinning of MoS2 is very reliable (with almost 100% success rate), can be easily scaled up, and is compatible with standard semiconductor process to generate heterostructures/patterns at nanometer scale, which may bring out interesting properties and new physics.
•First use of plasma alternative to solid material as an inert anode in aluminum electrolysis;•The anode product of electrolysis is oxygen;•Plasma anodes are available easily and without complicated ...operations;•Theoretically, the plasma anode is completely inert in the aluminum cell;
The aluminum industry is one of the major causes of CO2 emissions into the atmosphere, mainly caused by carbon anode consumption and the emission of perfluorocarbon gases. Carbon anodes are consumed by anodic reactions in the standard technology. The environmental constraints and the costs associated with the utilization of carbon anodes have, for many decades, led to the look for non-consumable anodes, called “inert anodes,” considered for years to be the future of aluminum production. However, the current research on inert anodes is limited to metal, ceramic, cermet, and gas anodes and remains impotent in solving the difficulties of anode consumption, CO2, and other greenhouse gas emissions. Here, we propose the utilization of argon plasma as an inert anode for aluminum electrolysis. The results from emission spectroscopy analysis and Density Functional Theory (DFT) calculations depict a production of positively charged argon ion (Ar+) at the anode region, which infuses into the electrolyte and reacts electrochemically with the oxy-fluoro aluminate complexes (Al2OF6)2-. For a current ≤ 0.4 A, the oxygen evolution occurs anodically from 2Al2OF62- + 4Ar+ → 4AlF3 + O2 + 4Ar, with no argon consumption. Furthermore, the aluminum is reduced cathodically, and the decomposition reaction is 2Al2O3 → 4Al + 3O2. This innovative approach enables carbon-free aluminum electrolysis, a large-scale reduction in greenhouse gas (GHG) emissions, which can be extended to similar electrolytic industries.
Regular nanoscopic ripple and dot patterns are fabricated on poly‐crystalline titanium samples by irradiation with 1.5 keV argon ions at normal incidence. The morphology of the nanostructures is ...investigated by scanning electron microscopy and scanning force microscopy. The ripple structures exhibit a saw‐tooth cross‐section profile. Electron backscatter diffraction experiments are performed to analyze the local grain structure. The study suggests a distinct correlation of the nanostructure morphology to the crystallographic orientation of the titanium surface.
OBJECTIVE:Xenon provides neuroprotection in multiple animal models; however, little is known about the other noble gases. The aim of the current study was to compare xenon, argon, and helium ...neuroprotection in a neonatal asphyxia model in rats.
DESIGN:Randomized controlled trial.
SETTING:Laboratory.
SUBJECTS:Seven-day-old postnatal Sprague-Dawley rats.
INTERVENTIONS:Seventy percent argon, helium, xenon, or nitrogen balanced with oxygen after hypoxic–ischemic brain injury.
MEASUREMENTS AND MAIN RESULTS:Control animals undergoing moderate hypoxic–ischemia endured reduced neuronal survival at 7 days with impaired neurologic function at the juvenile age compared with naïve animals. Severe hypoxic–ischemic damage produced a large cerebral infarction in controls. After moderate hypoxic–ischemia, all three noble gases improved cell survival, brain structural integrity, and neurologic function on postnatal day 40 compared with nitrogen. Interestingly, argon improved cell survival to naïve levels, whereas xenon and helium did not. When tested against more severe hypoxic–ischemic injury only, argon and xenon reduced infarct volume. Furthermore, postinjury body weight in moderate insult was lower in the helium-treated group compared with the naïve, control, and other noble gas treatment groups, whereas in the severe injurious setting, it is lower in both control and helium-treated groups than other groups. In the nondirectly injured hemisphere, argon, helium, and xenon increased the expression of Bcl-2, whereas helium and xenon increased Bcl-xL. In addition, Bax expression was enhanced in the control and helium groups.
CONCLUSIONS:These studies indicate that argon and xenon provide neuroprotection against both moderate and severe hypoxia–ischemic brain injury likely through prosurvival proteins synthesis.
Coating/substrate interface and oxide layers present in Inconel 625 film may cause significant impacts on its corrosion behavior. However, layered structure of Inconel 625 coatings remains poorly ...understood due to its requirement of high spatial resolution. This study applies X-ray reflectometry (XRR) to probe the layered structure of magnetron-sputtered Inconel 625 film with atomic spatial resolution. Our results indicate that there exists a 2 nm thick Cr-rich Inconel sublayer underneath the principal film. On top of the principal film, it is found a 2 nm thick oxide layer mainly consisting of NiO. In addition, we detected ~2 Å contamination layer on the sapphire substrate, although argon ion sputter cleaning had been applied to the substrate prior to deposition. By comparing the coatings with different deposition time, we observed that the thickness of principal Inconel 625 layer grows linearly with deposition time, with all other layers remaining constant. Our findings provide insight into the layered structures of Inconel 625 coatings with atomic-scale spatial resolution, and provide directions for future efforts that aim to improve the corrosion resistance of Inconel 625 coatings.
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•Multi-layered structure of Inconel 625 film is revealed with atomic-scale spatial resolution.•2.3 nm thick Cr-rich Inconel sublayer is found underneath the principal Inconel film.•Oxide layer with thickness of 2 nm is dominated by NiO.•2 Å and 15 Å thick contaminations are identified on the substrate and on the film respectively.•Principal Inconel 625 layer grows linearly with deposition time.
The nanoreactor approach first introduced by the group of Martı́nez Wang et al. Nat. Chem. 2014, 6, 1044–1048 has recently attracted much attention because of its ability to accelerate the discovery ...of reaction pathways. Here, we provide a comprehensive study of various simulation parameters and present an alternative implementation for the reactivity-enhancing spherical constraint function, as well as for the detection of reaction events. In this context, a fully automated postsimulation evaluation procedure based on RDKit and NetworkX analysis is introduced. The chemical and physical robustness of the procedure is examined by investigating the reactivity of selected homogeneous systems. The optimized procedure is applied at the GFN2-xTB level of theory to a system composed of HCN molecules and argon atoms, acting as a buffer, yielding prebiotically plausible primary and secondary precursors for the synthesis of RNA. Furthermore, the formose reaction network is explored leading to numerous sugar precursors. The discovered compounds reflect experimental findings; however, new synthetic routes and a large collection of exotic, highly reactive molecules are observed, highlighting the predictive power of the nanoreactor approach for unraveling the reactive manifold.
Recent research has highlighted the promising potential of cold atmospheric plasma (CAP) in cancer therapy. However, variations in study outcomes are attributed to differences in CAP devices and ...plasma parameters, which lead to diverse compositions of plasma products, including electrons, charged particles, reactive species, UV light, and heat. This study aimed to evaluate and compare the optimal exposure time, duration, and direction-dependent cellular effects of two CAPs, based on argon and helium gases, on glioblastoma U-87 MG cancer cells and an animal model of GBM. Two plasma jets were used as low-temperature plasma sources in which helium or argon gas was ionized by high voltage (4.5 kV) and frequency (20 kHz). In vitro assessments on human GBM and normal astrocyte cell lines, using MTT assays, flow cytometry analysis, wound healing assays, and immunocytochemistry for Caspase3 and P53 proteins, demonstrated that all studied plasma jets, especially indirect argon CAP, selectively induced apoptosis, hindered tumor cell growth, and inhibited migration. These effects occurred concurrently with increased intracellular levels of reactive oxygen species and decreased total antioxidant capacity in the cells. In vivo results further supported these findings, indicating that single indirect argon and direct helium CAP therapy, equal to high dose Temozolomide treatment, induced tumor cell death in a rat model of GBM. This was concurrent with a reduction in tumor size observed through PET-CT scan imaging and a significant increase in the survival rate. Additionally, there was a decrease in GFAP protein levels, a significant GBM tumor marker, and an increase in P53 protein expression based on immunohistochemical analyses. Furthermore, Ledge beam test analysis revealed general motor function improvement after indirect argon CAP therapy, similar to Temozolomide treatment. Taken together, these results suggest that CAP therapy, using indirect argon and direct helium jets, holds great promise for clinical applications in GBM treatment.
Motivated by possible atomic origins of the unidentified emission line detected at 3.55-3.57 keV in a stacked spectrum of galaxy clusters, an electron beam ion trap (EBIT) was used to investigate the ...resonant dielectronic recombination (DR) process in highly charged argon ions as a possible contributor to the emission feature. The He-like Ar DR-induced transition 1s22l-1s2l3l′ was suggested to produce a 3.62 keV photon near the unidentified line at 3.57 keV and was the starting point of our investigation. The collisional-radiative model NOMAD was used to create synthetic spectra for comparison with both our EBIT measurements and with spectra produced with the AtomDB database/Astrophysical Plasma Emission Code (APEC) used in the Bulbul et al. work. Excellent agreement was found between the NOMAD and EBIT spectra, providing a high level of confidence in the atomic data used. Comparison of the NOMAD and APEC spectra revealed a number of missing features in the AtomDB database near the unidentified line. At an electron temperature of Te = 1.72 keV, the inclusion of the missing lines in AtomDB increases the total flux in the 3.5-3.66 keV energy band by a factor of 2. While important, this extra emission is not enough to explain the unidentified line found in the galaxy cluster spectra.
Purpose: This study aims to compare the effects and prognosis of medical thoracoscopy-assisted argon plasma coagulation (APC) combined with electrosurgical unit (ESU) surgery, video-assisted thoracic ...surgery (VATS), and pleurodesis surgery, in providing appropriate treatment for elderly refractory pneumothorax patients.Methods: Patients with refractory pneumothorax aged over 65 years were divided into three groups: APC combined with ESU (N = 20), VATS (N = 26), and pleurodesis (N = 24). Data on demographic characteristics, lung function evaluation, and short- and long-term prognoses were collected.Results: Following surgery, compared with the APC-ESU and pleurodesis groups, patients in the VATS group demonstrated poor short-term prognoses, with high pleural effusion drainage levels and high visual analog scores (VAS; P <0.05). After the surgery, St. George’s Respiratory Questionnaire (SGRQ) scores in the pleurodesis group were slightly elevated, whereas SGRQ scores in both the APC-ESU and VATS groups demonstrated a continual decrease. Finally, medical resource consumption analysis demonstrated a significant difference in hospitalization costs among the three groups; the VATS group being the most expensive.Conclusion: Medical thoracoscopy-assisted APC combined with ESU is a safe, effective, and affordable treatment for elderly patients with refractory pneumothorax.
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