Gas Ions Research Articles

BODIPY‐Based Small‐Molecule Photoacoustic Probes for Biomedical Imaging

Advances in bioimaging technologies capable of visualizing physiological and pathological processes are of great significance for revealing diseases development and promoting clinical diagnosis and treatment. Photoacoustic (PA) imaging, utilizing small‐molecule probes, offers a promising approach for achieving high‐spatiotemporal‐imaging of dynamic biological process. The development of near‐infrared absorbing dyes has significantly contributed to the research of small‐molecule PA probes, particularly boron‐dipyrromethene derivatives (BODIPYs) known for their simple synthesis, tunable NIR photophysical properties and superior PA imaging abilities. This review highlights recent advances in biomedical applications of BODIPY‐based PA probes, including the design strategies, spectral characteristics, response mechanisms and applications for imaging biomarkers such as reactive oxygen/nitrogen species, gaseous signaling molecules and metal ions. The insights provided in this review are expected to guide future studies on small‐molecule PA probes for bioimaging and biosensing.

Comparative mosquitocidal and repellence activities of essential oil, nanoemulsion and main terpenes of Deverra tortuosa against Aedes albopictus with insights into the non-target effects

There is an urgent and renewed interest in searching for effective and green pesticides to control mosquitoes. In this framework, the essential oil (EO) of the plant Deverra tortuosa was hydrodistilled, and analysed using gas chromatography-flame ionisation detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS). Dillapiole (40.2%), elemicin (8.1%), and myristicin (6.3%), phenylpropanoids, and sabinene (4.3%) a common monoterpene, were found to be the major EO components. The oil nanoemulsion (ONE) was developed adopting a green protocol, and then characterised. The EO, ONE, and terpenes, particularly the phenylpropanoids possessed considerable mosquitocidal bioactivity against the Asian tiger mosquito, Aedes albopictus. A percentage of 100% larval mortality was recorded when insects were treated with a concentration of 40 μL/mL of ONE after 24 hours of treatment, while double of this concentration from EO and dillapiole was required to achieve the same activity. The LC50’s against larvae ranged between 7.6 and 60.7 μL/mL. For adults, LC50’s ranged between 6.4 and 50.9 μL/L. At sub-lethal concentrations (0.625-5.0 μL/cm2), EO materials significantly repelled Ae. albopictus, where a concentration of 5.0 μL/cm2 of EO and ONE provided 100% protection for up to180 min. As a proposed mechanism of action, the EO materials considerably inhibited the activity of acetylcholinesterase (AChE). The test materials were safe for the mosquitofish, Gambusia affinis, a common larvivorous fish, and Eisenia fetida earthworm. Test materials were also safe for the white albino rat in an oral bioassay at a limit dosage of 3500 mg/kg b.wt. The findings support the use of the EO, nanoemulsion, and phenylpropanoids of D. tortuosa as environmentally benign natural mosquitocodes to control Ae. albopictus.

Fluorescence imaging of individual ions and molecules in pressurized noble gases for barium tagging in 136Xe

The imaging of individual Ba2+ ions in high pressure xenon gas is one possible way to attain background-free sensitivity to neutrinoless double beta decay and hence establish the Majorana nature of the neutrino. In this paper we demonstrate selective single Ba2+ ion imaging inside a high-pressure xenon gas environment. Ba2+ ions chelated with molecular chemosensors are resolved at the gas-solid interface using a diffraction-limited imaging system with scan area of 1 × 1 cm2 located inside 10 bar of xenon gas. This form of microscopy represents key ingredient in the development of barium tagging for neutrinoless double beta decay searches in 136Xe. This also provides a new tool for studying the photophysics of fluorescent molecules and chemosensors at the solid-gas interface to enable bottom-up design of catalysts and sensors.

Defect engineering-induced Seebeck coefficient and carrier concentration decoupling in CuI by noble gas ion implantation

Copper(I) iodide, CuI, is the leading p-type nontoxic and earth-abundant semiconducting material for transparent electronics and thermoelectric generators. Defects play a crucial role in determining the carrier concentration, scattering process, and, therefore, the thermoelectric performance of a material. As a result of defect engineering, the power factor of thin film CuI was increased from 332±32 to 578±58 μW m−1K−2 after implantation with noble gas ions (Ne, Ar, or Xe). The increased power factor is due to a decoupling of the Seebeck coefficient and electrical conductivity identified through a changing scattering mechanism. Ion implantation causes the abundant production of Frenkel pairs, which were found to suppress compensating donors in CuI, and this scenario was also supported by density functional theory calculations. The compensating donor suppression led to a significantly improved Hall carrier concentration, increasing from 6.5×1019±0.1×1019 to 11.5×1019±0.4×1019 cm−3. This work provides an important step forward in the development of CuI as a transparent conducting material for electronics and thermoelectric generators by introducing beneficial point defects with ion implantation.

Study on the aerodynamic characteristics of reentry capsule with obtuse head inverted cone under hypersonic chemical nonequilibrium flow

Abstract During spacecraft reentry, the aerodynamic characteristics of the reentry capsule with a sizeable obtuse head inverted cone (OBHIC) in a hypersonic state are the key factors in the design of controlled reentry trajectory, the design of trim angle of attack (AoA), and the accuracy of fall point of capsules. This paper establishes a numerical simulation algorithm of a hypersonic chemical nonequilibrium flow field by considering high-temperature real gas effects. The reentry capsule’s aerodynamic and flow field characteristics are predicted and analyzed. The component transport equations for chemical reactions are added to the Navier-Stokes equations, enabling precise modeling of gas molecule vibrational excitation and ionization processes. A half-model multi-block structured mesh is employed to construct the aerodynamic profile of the reentry capsule with OBHIC. The aerodynamic characteristics and pressure distribution of the reentry capsule were calculated and analyzed under the typical conditions of flight altitude of 40~80 km, flight velocity of 6~27 Ma, and AoA of 15°~24°. The results of the aerodynamic characteristics prediction show that the aerodynamic characteristics of the reentry capsule are little affected by the incoming flow velocity in a hypersonic state but significantly affected by the AoA. As the AoA increases, the lift coefficient CL increases linearly, the drag coefficient CD decreases linearly, the lift-to-drag ratio K rises linearly, and K increases from 0.19 to 0.29. In its hypersonic state, the reentry capsule exhibits a low lift-to-drag ratio, characterized by high drag and low lift coefficients. The results of this paper play an essential role in the reentry flight dynamics and reentry trajectory design of the reentry capsule. Moreover, it can further ensure the safety and reliability of the reentry flight of spacecraft.

Mechanism of generating collisionless shock in magnetized gas plasma driven by laser-ablated target plasma

The mechanism of generating collisionless shock in magnetized gas plasma driven by laser-ablated target plasma is investigated by using one-dimensional full particle-in-cell simulation. The effect of finite injection time of target plasma, mimicking the finite width of laser pulse, is taken into account. It was found that the formation of a seed-shock requires a precursor. The precursor is driven by gyrating ions, and its origin varies depending on the injection time of the target plasma. When the injection time is short, the target plasma entering the gas plasma creates a precursor; otherwise, gas ions reflected by the strong piston effect of the target plasma create a precursor. The precursor compresses the background gas plasma, and subsequently, a compressed seed-shock forms in the gas plasma. The parameter dependence on the formation process and propagation characteristics of the seed-shock was discussed. It was confirmed that the seed-shock propagates through the gas plasma exhibiting behavior similar to the shock front of supercritical shocks.

Optimizing the resistivity of colloidal SnO2 thin films by ion implantation and annealing

Tin oxide (SnO2) is a critical material for a wide range of applications, such as in perovskite solar cells, gas sensors, as well as for photocatalysis. For these applications the transparency to visible light, high availability, cheap fabrication process and high conductivity of SnO2 benefits its commercial deployment. In this paper, we demonstrate that the resistivity of widely colloidal SnO2 can be reduced by noble gas ion beam modification. After low energy argon implantation with a fluence of 4×1015 at.cm−2 at 25keV and annealing at 200°C in air, the resistivity of as-deposited film was reduced from (178±6)μΩcm to (133±5)μΩcm, a reduction of 25%. Hall effect measurements showed that the primary cause of this is the increase in carrier concentration from (8.1±0.3)×1020 cm−3 to (9.9±0.3)×1020 cm−3. Annealing at 200°C resulted in the removal of defect clusters introduced by implantation, while annealing at 300°C resulted in the oxidation of the films, increasing their resistivity. The concentration of oxygen vacancy defects can be controlled by a combination of low energy noble gas ion implantation and annealing, providing promising performance increases for potential applications of SnO2 where a low resistivity is crucial.

A SIMPLE SOURCE OF METAL AND GAS IONS FOR ION BEAM TECHNOLOGICAL INSTALLATIONS

At the stand of the Institute of Applied Physics of the National Academy of Sciences of Ukraine, a small-sized spattering source of metal and gas ions was developed, manufactured and tested. Ionization of sputtered atoms occurs by fast oscillating electrons in a longitudinal magnetic field. A beam containing ions of plasma-forming gas and metal is output through an emission hole in the anticathode. The source has high ion current stability, is easy to maintain, and can generate ions from any conductive solid. Modeling and manufacturing of an ion-optical system for this source, which is part of the injector of the implanter of the Institute of Applied Physics of the National Academy of Sciences of Ukraine, was carried out.

Determination of Synthetic Opioids Belonging to the Fentanyl Class in Silt Using Electron Ionization Gas Chromatography-Mass Spectrometry (GC-MS).

An extraction protocol from silt sediment of fentanyl and three analogs: acetylfentanyl, thiofentanyl and acetylthiofentanyl, spiked at two concentrations each and separately (at ∼1 and ∼10 µg/g), is described. In addition, the identity of the fentanyls preliminarily identified by electron ionization gas chromatography-mass spectrometry (EI-GC-MS) analysis, can be corroborated by reacting each opioid in the silt’s extract with 2,2,2-trichloroethoxycarbonyl chloride (Troc-Cl). Reaction between Troc-Cl and each opioid generates two unique products that can be used to retrospectively identify the original opioid therefore serving as a corroborating tool for known opioids as well as new, unknown fentanyl analogs.

GA-NIFS: an extremely nitrogen-loud and chemically stratified galaxy at z ~ 5.55

ABSTRACT We report the chemical abundance pattern of GS_3073, a galaxy hosting an overmassive active black hole at $z=5.55$, by leveraging observations from JWST/NIRSpec and Very Large Telescope/VIsible Multi-Object Spectrograph. Based on the rest-frame ultraviolet (UV) emission lines, which trace high-density ($\sim 10^5~{\rm cm^{-3}}$) and highly ionized gas, we derive $\rm \log (N/O) = 0.42^{+0.13}_{-0.10}$. At an estimated metallicity of $0.2~Z_{\odot }$, this is the most extreme nitrogen-rich object found by JWST thus far. In comparison, the relative carbon abundance derived is $\rm \log (C/O) = -0.38^{+0.13}_{-0.11}$, which is not significantly higher than those in local galaxies and stars with similar metallicities. We also found potential detection of [Fe vii]$\lambda 6087$ and [Fe xiv]$\lambda 5303$, both blended with [Ca v]. We inferred a range of Fe abundances compatible with those in local stars and galaxies. Overall, the chemical abundance pattern of GS_3073 is compatible with enrichment by supermassive stars with $M_* \gtrsim 1000~M_\odot$, asymptotic giant branch stars, or Wolf–Rayet stars. Interestingly, when using optical emission lines that trace lower density ($\sim 10^3~{\rm cm}^{-3}$) and lower ionization gas, we found a sub-solar N/O ratio, consistent with local galaxies at the same metallicity. We interpret the difference in N/O derived from UV lines and optical lines as evidence for a stratified system, where the inner and denser region is both more chemically enriched and more ionized. Our results suggest that nitrogen loudness in high-z galaxies might be confined to the central, dense, and highly ionized regions of the galaxies, while the bulk of the galaxies evolves more normally.

Multiphysical description of atmospheric pressure interface chemical ionisation in MION2 and Eisele type inlets

Abstract. Chemical ionisation inlets are fundamental instrument components in chemical ionisation mass spectrometry (CIMS). However, the sample gas and reagent ion trajectories are often understood only in a general and qualitative manner. Here, we evaluate two atmospheric pressure interface chemical ionisation inlets (MION2 and Eisele type inlet) with 3D computational fluid dynamics physicochemical models regarding the reagent ion and sample gas trajectories and estimate their efficiencies of reagent ion production, reagent ion delivery from the ion source volume into the ion–molecule mixing region, and the interaction between reagent ions and target molecules. The models are validated by laboratory measurements and quantitatively reproduce observed sensitivities to tuning parameters, including ion currents and changes in mass spectra. The study elucidates how the different transport and chemical reactions proceed within the studied inlets, where space charge can already be relevant at ion concentrations as low as 107 cm−3, and compares the two investigated inlet models. The models provide insights into how to operate the inlets and will help in the development of future inlets that further enhance the capability of CIMS.

CAVITY: Calar Alto Void Integral-field Treasury surve. I. First public data release

The Calar Alto Void Integral-field Treasury surveY (CAVITY) is a legacy project aimed at characterising the population of galaxies inhabiting voids, which are the most under-dense regions of the cosmic web, located in the Local Universe. This paper describes the first public data release (DR1) of CAVITY, comprising science-grade optical data cubes for the initial 100 out of a total of sim 300 galaxies in the Local Universe ($0.005 < z < 0.050$). These data were acquired using the integral-field spectrograph PMAS/PPak mounted on the 3.5m telescope at the Calar Alto observatory. The DR1 galaxy sample encompasses diverse characteristics in the color–magnitude space, morphological type, stellar mass, and gas ionisation conditions, providing a rich resource for addressing key questions in galaxy evolution through spatially resolved spectroscopy. The galaxies in this study were observed with the low-resolution V500 set-up, spanning the wavelength range 3745–7500 with a spectral resolution of 6.0 (FWHM). Here, we describe the data reduction and characteristics and data structure of the CAVITY datasets essential for their scientific utilisation, highlighting such concerns as vignetting effects, as well as the identification of bad pixels and management of spatially correlated noise. We also provide instructions for accessing the CAVITY datasets and associated ancillary data through the project's dedicated database.

Enhanced DC surface discharge characteristics of epoxy composites treated by dielectric barrier discharge plasma fluorination and its mechanisms

Surface flashover is a destructive high-voltage discharge phenomenon greatly limiting the update of modern power electronic and electrical equipment. Surface plasma treatment is a high-energy, eco-friendly, and convenience method, it changes the surface properties and owns potential to improve flashover voltage. In the present work, plasma fluorination (PF) technique are used to treat EP/Al2O3 composites, surface morphology, element and bonds content, surface trap, conductivity, charging, and DC flashover voltage are tested and simulated, the effects of plasma on surface discharge are explained through the investigation from microscopic molecular reactions to macroscopic flashover characteristics. It indicates the 20 min PF modified sample exhibits the superior DC flashover performance, increasing by 17 % compare to untreated sample. During PF modification, the epoxy chains are degraded and fluorinated, the degradation rather than fluorination of molecular chains introduce large amounts of shallow traps into the composites, accelerating carriers’ migration and improving surface conductivity, causing surface charges to dissipate through surface conductance. Consequently, the surface electric field distortion degree reduces, and the subsequent gas ionization and plasma formation in the gas phase is suppressed, leading to the improvement of DC flashover voltage after PF modifications.

Biochar captures ammonium and nitrate in easily extractable and strongly retained form without stimulating greenhouse gas emissions during composting.

During composting of organic waste, nitrogen is lost through gaseous forms and ion leaching. Biochar has been shown to capture mineral nitrogen (Nmin: NH4 + and NO3 -) from compost, which we hypothesize reduces N2O formation. However, associating Nmin captured by biochar with the dynamics of N2O and other greenhouse gas (GHG) emissions during composting remains unstudied and was the aim of this work. We composted (outdoor for 148 days) together kitchen scraps (43.3% dw, where dw is dry weight), horse manure (40.9% dw), and wheat (Triticum aestivum L) straw (15.8% dw) without (Control) or with biochar (Bc, 15% compost dw). The biochar consisted of hardwood and softwood pieces pyrolyzed at 680°C and exhibited 60% of particles with 4-8mm. We monitored compost GHG (CO2, CH4, N2O) emissions, Nmin content in compost and biochar particles (sequential extractions), and biochar surface transformations (SEM-EDX and 13C-NMR spectroscopy) along composting. Biochar did not significantly reduce or increase GHG emissions and Nmin content (mg kg-1) in compost. However, the final NO3 - amount (g compost pile-1) in the Bc treatment was significantly higher (54%) compared to the Control, indicating lower NO3 - losses. Despite the high aromaticity and minimal contribution of carboxyl C to the biochar structure, biochar retained NH4 +, mainly in easily extractable form (55%), in the first 2 weeks of composting and mainly in strongly retained form (75%) in the final compost. The NO3 - content in biochar increased continuously during composting. In the final compost, the NO3 - content extracted from biochar was 164 (37%, easily extractable), 80 (19%, moderately extractable), and 194mg NO3 --N kg-1 (44%, strongly retained). Although Nmin retention in biochar was not accompanied by lower N2O emissions, contradicting our hypothesis, we demonstrated the efficacy of biochar to recover Nmin from organic waste without stimulating GHG emissions.

Revealing the flashover mechanism of EP/GF composite insulation under DC combined harmonic voltage

Abstract In ultra-high voltage converter stations, the phenomenon of flashover along the outer insulation of dry hollow reactors made of epoxy/glass fiber composites poses a potential threat to the stability of the power system. To enhance its flashover performance under varying complex conditions, it is necessary to conduct in-depth research on the flashover mechanism of this material under different voltage forms. This study conducted tests on the flashover voltage, surface space charge distribution, and partial discharge parameters under varying AC-DC ratios and AC frequencies, and exploring their relationships. The results show that the DC content in the AC-DC ratio decreases, the flashover voltage decreases, the apparent total discharge of partial discharges increases, and the maximum surface space charge density decreases. The main influencing factor is the increase in the number of seed charges involved in gas ionization. Increasing the AC frequency, the flashover voltage decreases, the apparent total discharge increases significantly, and the surface charge density remains basically unchanged. The main reason is that the change in the number of alternating cycles further increases the number of seed charges. This study reveals the flashover mechanism of epoxy/glass fiber composites under different voltage forms, which provides theoretical support for subsequent material modification.

No evidence of active galactic nucleus features in the nuclei of Arp 220 from JWST/NIRSpec IFS

Context. Arp 220 is the nearest ultra-luminous infrared galaxy. It shows evidence of 100 pc scale molecular outflows that are likely connected with galaxy-scale outflows traced by ionised and neutral gas. The two highly obscured nuclei of Arp 220 are sites of intense star formation, with extreme (far-infrared based) star formation rate surface densities, ΣSFR ≳ 103 M⊙ yr−1 kpc−2. Despite extensive investigations that searched for active galactic nucleus (AGN) activity in the Arp 220 nuclei, direct evidence remains elusive. Aims. We present JWST/NIRSpec integral field spectroscopy (IFS) observations covering the 0.9 − 5.1 μm wavelength range of the innermost (5″ × 4″, i.e. 1.8 × 1.5 kpc) regions of Arp 220. The primary goal is to investigate the potential presence of AGN signatures in the nuclear regions by analysing the spectra extracted from circular apertures with a radius of 55 pc (0.15″) around each of the two nuclei. Methods. The analysis aims to identify highly ionised gas emission lines (with ionisation potential > 54 eV) and other spectral features indicative of AGN activity. Atomic and molecular gas kinematics were also taken into account to study the outflow signatures at < 60 pc scales. Results. We identify ∼70 atomic and ∼50 molecular emission lines in the nuclear spectra of Arp 220. We used recombination line ratios to measure optical extinctions in the range AV ∼ 11 − 14 mag. High-ionisation lines are not detected, except for the [Mg IV] line at 4.49 μm, which we interpret as due to shocks rather than to AGN ionisation. We identify broadening and multiple kinematic components in the H I and H2 lines caused by outflows and shocks, with velocities up to ∼550 km s−1. Significantly higher velocities (up to ∼900 km s−1) are detected in the off-nuclear regions, but they do not conclusively represent direct evidence for AGN activity. Broad-line region components are not detected in any permitted emission line within the NIRSpec wavelength range. Conclusions. Even with the unprecedented sensitivity of JWST/NIRSpec IFS, achieving an unambiguous identification or exclusion of the presence of an AGN in the Arp 220 system remains challenging because of its extreme dust obscuration.

AGN STORM 2. IX. Studying the Dynamics of the Ionized Obscurer in Mrk 817 with High-resolution X-Ray Spectroscopy

We present the results of the XMM-Newton and NuSTAR observations taken as part of the ongoing, intensive multiwavelength monitoring program of the Seyfert 1 galaxy Mrk 817 by the AGN Space Telescope and Optical Reverberation Mapping 2 (AGN STORM 2) Project. The campaign revealed an unexpected and transient obscuring outflow, never before seen in this source. Of our four XMM-Newton/NuSTAR epochs, one fortuitously taken during a bright X-ray state has strong narrow absorption lines in the high-resolution grating spectra. From these absorption features, we determine that the obscurer is in fact a multiphase ionized wind with an outflow velocity of ∼5200 km s−1, and for the first time find evidence for a lower ionization component with the same velocity observed in absorption features in the contemporaneous Hubble Space Telescope spectra. This indicates that the UV absorption troughs may be due to dense clumps embedded in diffuse, higher ionization gas responsible for the X-ray absorption lines of the same velocity. We observe variability in the shape of the absorption lines on timescales of hours, placing the variable component at roughly 1000 R g if attributed to transverse motion along the line of sight. This estimate aligns with independent UV measurements of the distance to the obscurer suggesting an accretion disk wind at the inner broad line region. We estimate that it takes roughly 200 days for the outflow to travel from the disk to our line of sight, consistent with the timescale of the outflow's column density variations throughout the campaign.

SnO2 Nanobelts as a Chemiresistive Platform for an On-Chip Multisensory “Spectrometer” to Selectively Gauge Ions of Inert Gases

SnO₂ Nanobelts as a Chemiresistive Platform for an On-Chip Multisensory “Spectrometer” to Selectively Gauge Ions of Inert Gases

Development of electron detectors for the BRAND experiment

The BRAND experiment employs detectors that utilize gas ionization and plastic scintillators, integrated with custom-designed front-end electronics, aimed at measuring the correlation coefficients in neutron beta decay. This article focuses on the characterization and performance of a newly developed electron detector prototype featuring custom-designed front-end electronics. The characterization results indicate an weak gain dependency of the scintillator when exposed to a radioactive source, varying along its length and width.

Excitation and ionization of a diagnosis gas in front of the flexible μ tube plasma and in a diagnosis tube

The noble gases Helium, Argon, Krypton and even Xeon have been applied as discharge gases for the flexible μ tube plasma (FμTP) with comparable ionization efficiencies. It was assumed that a temporally and spatially limited potential plays a major role in the generation of reactant ions responsible for protonation in the surrounding air. However, the excited and ionized species of ambient air cannot be detected directly by emission spectroscopy because there is no known emission wavelength within the detectable range. In this work, a diagnosis gas was introduced as a substitute for the surrounding air to understand the excitation and ionization outside the discharge capillary. It was found that with Ne, Ar, Kr, Xe as plasma gases the diagnosis gas He can be excited during the positive half cycle. The emission of He 706 nm and N2+ 391 nm propagate with and against diagnosis gas flow directions in case of He and Ne driven plasmas. In case of Ar, Kr, and Xe driven plasmas, the emission of both species mainly develops against the diagnosis gas and the shapes of He 706 nm are wide. Further on, the diagnosis gas He is also excited even though there is a glass wall between the plasma gas flow and diagnosis gas flow. These findings demonstrate that the transient potential is responsible for the excitation of the diagnosis gas, not penning ionization or charge transfer between discharge plasma and diagnosis gas.