Fraction Of Ions Research Articles

Epsilon Canis Majoris: The Brightest Extreme-ultraviolet Source with Surprisingly Low Interstellar Absorption

Abstract The B2 star Epsilon Canis Majoris (ϵ CMa), at parallax distance d = 124 ± 2 pc, dominates the H i photoionization of the Local Interstellar Cloud. At its closer parallax distance compared to previous estimates, ϵ CMa has a 0.9 mag fainter absolute magnitude M V = −3.97 ± 0.04. We combine measurements of distance with the integrated flux f = (41.5 ± 3.3) × 10−6 erg cm−2 s−1 and angular diameter θ d = 0.80 ± 0.05 mas to produce a consistent set of stellar parameters: radius R = 10.7 ± 0.7 R ⊙, mass M = 13.1 ± 2.3 M ⊙, gravity log g = 3.50 ± 0.05 , effective temperature T eff ≈ 21,000 K, and luminosity L ≈ 20,000 L ⊙. These parameters place ϵ CMa outside the β Cephei instability strip, consistent with its observed lack of pulsations. The observed extreme-ultraviolet spectrum yields a hydrogen photoionization rate ΓHI ≈ 10−15 s−1 (at Earth). The total flux decrement factor at the Lyman limit (ΔLL = 5000 ± 500) is a combination of attenuation in the stellar atmosphere (Δstar = 110 ± 10) and interstellar medium (ΔISM = 45 ± 5) with optical depth τ LL = 3.8 ± 0.1. After correcting for interstellar H i column density N HI = (6 ± 1) × 1017cm−2, we find a stellar LyC photon flux ΦLyC ≈ 3000 cm−2 s−1 and ionizing luminosity Q LyC = 1045.7±0.3 photons s−1. The photoionization rate ΓH ≈ (1–2) × 10−14 s−1 at the cloud surface produces an ionization fraction (30%–40%) for total hydrogen density n H = 0.2 cm−3. With its 27.3 ± 0.4 km s−1 heliocentric radial velocity and small proper motion, ϵ CMa passed within 9.3 ± 0.5 pc of the Sun 4.4 Myr ago, with a 180 times higher photoionization rate.

Exposure pathways (diet, dissolved or particulate substrate) of rare earth elements to aquatic organisms.

The global extraction and use of rare earth elements (REEs) continue to rise as they are implemented in technologies that improve human and environmental livelihoods. However, the general understanding of transfer processes and fates of REEs in aquatic systems remains limited. Here, we aim to determine the REEs' main exposure pathways, e.g., particulate fraction, diet, or dissolved (ionic) fractions, to three benthic and three pelagic organisms. They were maintained under laboratory conditions and exposed to natural river water, with or without a sand substrate and an adapted diet. The organisms include northern clearwater crayfish (Faxonius propinquus), chinese mystery snail (Cipangopaludina chinensis), black sandshell mussel (Ligumia recta), striped shiner minnows (Luxilus chrysocephalus), Daphnia magna, and Euglena gracilis. The combined results of REE concentrations, fractionations, and anomalies highlighted that pelagic organisms are characterized by heavy REEs enrichment indicating they mainly uptake REEs in the dissolved form with high bioaccumulation potential, i.e., bioconcentration (BCF) > 1 and diet accumulation factors (DAF) < 1. Pelagic organisms exhibited relatively low REE concentrations in their tissues ([La] ranging from 4.6 to 57.7 µg kg-1 in minnows, 18.4 µg kg-1 in whole body D. magna, and 32.2 µg kg-1 in E. gracilis). On the other hand, snails and mussels were enriched in light REEs showing they mainly uptake REEs through their respective diets and particulate sand substrate. Relative to pelagic organisms, mussels and snails have higher DAFs (161.2 and 18.6, respectively) and REE levels in their soft tissues ([La] of 5700 µg kg -1 and 650 µg kg -1, respectively), but DAF for crayfish remains < 1. In summary, under environmental-relevant conditions, the six aquatic organisms has the potential to accumulate REEs through various uptake pathways. Nevertheless, our results confirming preferential uptake pathways of the six organisms can help select appropriate species in future studies to monitor REE exposure from vaious fractions: dissolved, particulate forms or in the food webs (i.e., diet).

Magnon and electromagnon excitations in Dy0.9Nd0.1FeO3 single crystals tuned with temperature and magnetic field

Magnon and electromagnon excitations in RFeO3 (where R is a rare-earth element) are associated with the orderings of Fe and R ions, respectively, both of which strongly depend on temperature and applied magnetic field. Herein, by employing the magnetic and electric components of terahertz radiation, we have investigated the temperature and magnetic field dependent magnon and electromagnon excitations in Dy0.9Nd0.1FeO3 single crystals. Our results demonstrate that a small fraction of Nd-substituted Dy ion in Dy1−xNdxFeO3 (with x = 0.1) single crystals shows negligible influence on quasi-ferromagnetic (q-FM) and quasi-antiferromagnetic (q-AFM) modes when the temperature is above TNR, the ordering temperature of rare-earth ions. By contrast, introduction of 10% doping concentration of Nd element leads to changes in exchange interaction of rare-earth ions, consequently altering the frequencies of the electromagnon. Applying magnetic field along different crystal axes can tune the frequency of both q-FM and q-AFM modes and even trigger Fe3+-based spin reorientation phase transition. Furthermore, application of magnetic field can suppress the ordering of rare-earth ions and electromagnon excitation. We anticipate that our findings can advance the understanding of magnetoelectric coupling mechanisms and pave the way for the development of advanced multiferroic materials with tailored properties.

Revisiting the BE99 method for the study of outflowing gas in protostellar jets

An established method for measuring the hydrogen ionisation fraction in shock-excited gas is the BE99 method, which utilises six bright forbidden emission lines: S\,II N\,II 6583, and O\,I 6363. The main assumptions of this technique are that the gas is in a low-excitation state ($x_ e &lt; 0.3$) and that the equilibrium of the underlying ionisation network is reached. Our aim is to extend the BE99 method by including more emission lines in the blue and near-infrared part of the spectrum ($ and by considering higher hydrogen ionisation fractions ($x_ e &gt; 0.3$). In addition, we investigate how a non-equilibrium state of the gas and the presence of extinction influence the BE99 technique. We numerically solved a network of ionisation reactions in the time domain, which lead to the BE99 equilibrium. We applied the BE99 method on synthetic spectra also in the non-equilibrium state. We extented the BE99 technique to higher ionisation fractions by considering additional reactions, which involve higher ionisation states of oxygen, nitrogen, and sulphur. We tested our concepts on the low-excitation outflow of Par Lup 3-4 and the high-excitation 244-440 Proplyd in Orion. Many additional emission line ratios can in principle be exploited as extended curves (or stripes) in the ($x_ e T_ e $) diagram. If the BE99 equilibrium is reached and extinction is corrected for, all stripes overlap in one location in the ($x_ e T_ e $) diagram indicating the existing gas parameters. We find that the BE99 equilibrium is reached faster than the hydrogen recombination time. The application to the Par Lup 3-4 outflow shows that the classical BE99 lines together with the N\,I lines do not meet in one location in the ($x_ e T_ e $) diagram. This indicates that the gas parameters derived from the classical BE99 method are not fully consistent with other observed line ratios. A multi-line approach is necessary to determine the gas parameters. From our analysis we derive $n_e cm cm $, $T_e = 7\,600\ K K $, and $x_e 0.027-0.036$ for the Par Lup 3-4 outflow. For the 244-440 Proplyd we were able to use the line ratios of S\,II O\,I and OII 7330 in the BE99 diagram to estimate the ionisation fraction at knot E3 ($x_e = 0.58 The BE99 method can be extended by utilising more emission line ratios in the ($x_ e T_ e $) diagram and considering higher ionisation states. Exploiting new line ratios reveals more insights on the state of the gas. Our analysis indicates, however, that a multi-line approach is more robust in deriving gas parameters, especially for high-density gas.

Model-independent reconstruction of UV luminosity function and reionization epoch

We conduct a first comprehensive study of the Luminosity Function (LF) using a non-parametric approach. We use Gaussian Process to fit available luminosity data between redshifts z ∼ 2-8. Our free-form LF in the non-parametric approach rules out the conventional Schechter function model to describe the abundance-magnitude relation at redshifts z=3 and 4. Hints of deviation from the Schechter function are also noticed at redshifts 2, 7 and 8 at lower statistical significance. Significant deviation starts for brighter ionizing sources at M UV ≲ -21. The UV luminosity density data at different redshifts are then derived by integrating the LFs obtained from both methods with a truncation magnitude of -17. In our analysis, we also include the first 90 arcmin2 JWST/NIRCam data at z ∼ 9-12. Since at larger magnitudes, we do not find major deviations from the Schechter function, the integrated luminosity density differs marginally between the two methods. Finally, we obtain the history of reionization from a joint analysis of UV luminosity density data along with the ionization fraction data and Planck observation of Cosmic Microwave Background. The history of reionization is not affected by the deviation of LFs from Schechter function at lower magnitudes. We derive reionization optical depth to be τ re = 0.0494+0.0007 -0.0006 and the duration between 10% and 90% completion of ionization process is found to be Δ z ∼ 1.627+0.059 -0.071.

Computational Analysis of Mixed-Anion Inorganic Materials for Secondary Battery Cathode Materials

For decades, battery design and development were based on the idea that the only possible source of redox in Li-ion cathode was on the transition metal. More recently, there has been exploration into the notion that anions could provide an extra capacity and energy density source for batteries. Nonetheless, anion redox is frequently linked with the irreversible discharge of oxygen from battery cathodes, presenting a notable obstacle to utilizing anion redox for creating enhanced batteries. Many studies have been conducted to effectively harness the reversible oxygen redox while preventing irreversible oxygen loss.1 However, various methods and their understandings are still insufficient.In this situation, an anion substitution approach could be one of the remedies to utilize oxygen redox reversibility and understand its mechanism. Recently, Leube et al. reported on sulfur selenide mixed-anion cathode, which actually stored energy through stable anion redox reactions and also showed good cycle performance.2 We suggest that oxysulfides form a class of mixed-anion compounds that have properties making them potentially promising cathode materials. We apply isovalent anion substitution to oxide cathodes, with a fraction of oxygen ions replaced by sulfur ions. This isovalent substitution leaves the oxidation state of metals unchanged, thus having no impact on the overall quantity of available cation redox. At the same time, substituting sulfur ions allows us to regulate the anion p-states within the materials, which control the activity of anion redox in the system.We first calculate the solubility limit of sulfur in oxide forming the solid solution oxysulfide. We model lithium cathode materials with oxygen and sulfur mixed in anion sites from 0 to 100%, based on structural prototypes known for anion redox behavior, considering 19 transition metals. We also model sulfur and selenium mixed cathodes, which have been experimentally reported.2 By comparing these two systems within the same prototype, we can identify the factors that make mixed-anion cathode difficult to synthesize. In fact, there are relatively few experimental or theoretical reports on oxysulfide synthesis. Therefore, this study aims to provide a theoretical interpretation of why it is challenging to form solid solution oxysulfide compared to sulfoselenide. We perform featurization on materials, including basic information, local and global structure features, etc. Using these features, we apply a machine learning technique to identify the key factors that hinder mixed-anion system synthesis. Our findings suggest the features that make it difficult to dissolve sulfur into oxide, offering a theoretical guide for constructing other types of mixed-anion systems. Reference A. S. Menon, M. J. W. Ogley, A. R. Genreith-Schriever, C. P. Grey, and L. F. J. Piper, Annu Rev Mater Res, 54, 199–221 (2024)B. Leube, C. Robert, D. Foix, B. Porcheron, R. Dedryvère, G. Rousse, E. Salager, P. Cabelguen, A. Abakumov, H. Vezin, M. Doublet, J. Tarascon, Nature Communications 2021 12:1, 12, 1–11 (2021)

Nanodosimetric investigation of the track structure of therapeutic carbon ion radiation part2: detailed simulation

Objectivea previous study reported nanodosimetric measurements of therapeutic-energy carbon ions penetrating simulated tissue. The results are incompatible with the predicted mean energy of the carbon ions in the nanodosimeter and previous experiments with lower energy monoenergetic beams. The purpose of this study is to explore the origin of these discrepancies.Approachdetailed simulations using the Geant4 toolkit were performed to investigate the radiation field in the nanodosimeter and provide input data for track structure simulations, which were performed with a developed version of the PTra code.Main resultsthe Geant4 simulations show that with the narrow-beam geometry employed in the experiment, only a small fraction of the carbon ions traverse the nanodosimeter and their mean energy is between 12% and 30% lower than the values estimated using the SRIM software. Only about one-third or less of these carbon ions hit the trigger detector. The track structure simulations indicate that the observed enhanced ionization cluster sizes are mainly due to coincidences with events in which carbon ions miss the trigger detector. In addition, the discrepancies observed for high absorber thicknesses of carbon ions traversing the target volume could be explained by assuming an increase in thickness or interaction cross-sections in the order of 1%.Significancethe results show that even with strong collimation of the radiation field, future nanodosimetric measurements of clinical carbon ion beams will require large trigger detectors to register all events with carbon ions traversing the nanodosimeter. Energy loss calculations of the primary beam in the absorbers are insufficient and should be replaced by detailed simulations when planning such experiments. Uncertainties of the interaction cross-sections in simulation codes may shift the Bragg peak position.

Studies of beam ion confinement to enhance plasma performance on EAST

A key physics issue for achieving steady-state high-performance plasmas on EAST tokamak is to decrease beam-ion losses to improve plasma confinement during neutral beam injections (NBIs). To decrease the beam losses, previous counter-I p NBI injections are upgraded to co-I p injections. Analysis shows that due to the reversed direction of drift across the flux surfaces caused by the pitch angle, the beam prompt loss fraction decreases from about 49% to 3% after the upgrade. Moreover, because of the change of entire beam path, beam shine-through (ST) loss fraction for counter-I p tangential and counter-I p perpendicular injections is reversed to co-I p tangential and co-I p perpendicular injections, respectively. Due to the change in the initial trapped-confined beam ion fraction caused by the peaked pitch profiles, the losses induced by toroidal ripple field are also reversed after the upgrade. To further improve the beam-ion confinement under the present NBI layout, the amplitudes of toroidal field are increased from 1.75 to 2.20 T. Result shows that, due to the smaller orbit width and peaked pitch angle profile, the beam prompt loss power is lower with higher toroidal field. Due to the synergy of higher initial trapped-confined beam ion fraction and narrower Goldston-White-Boozer (GWB) boundary, the loss induced by ripple diffusion is higher with higher toroidal field. The combined effect of beam ST loss, prompt loss and ripple loss, contributes to the increase in beam ion density. The decrease in beam loss power enhances beam heating efficiency, especially the fraction of beam heating ions. Finally, comparison between simulation and measurement by 235U fission chamber (FC) indicates that the increase in neutron rate is mainly contributed by improvement of beam-ion confinement. This study can provide potential support for beam operation and high-T i experiment on EAST tokamak.

Adsorbate-induced effects on the H− ion collisions with Na/Ag(111) and K/Ag(111) surfaces

The H− ion survival probabilities following on-top collisions with Na adsorbates deposited on Ag(111) at low coverage, are investigated for a wide range of exit angles from 20° to 90° measured from surface, and for various incident ion energies. A wave packet propagation approach is used in these calculations. The survival probabilities exhibit a series of well-defined peaks located at certain exit angles, that are indicative of avoided crossings between the various energy levels involved in the projectile/adsorbate/surface interaction. Both image states and the back-and-forth electronic motion between the ion projectile and the adsorbate/surface system contribute to the electronic population recaptured during the exit trajectory. For ion-surface collisions away from the on-top configuration, but in the close vicinity of adsorbates, a model is proposed to describe the variation of the H− projectile's distance of closest approach to the adsorbate-covered Ag(111) surface in terms of the ion's impact point on surface, e.g., starting from the on-top collision with a single adsorbate and gradually moving away, towards the “clean” surface. The distance of closest approach is a key factor in calculating correctly the ion survival probabilities in the close region around the adsorbate, where the scattered ion fractions are affected the most. Results are shown for H− in interaction with K/Ag(111).

Antimicrobial Activity of Diffusible Substances Produced by Lactococcus lactis Against Bacillus cereus in a Non-Contact Co-Culture Model

The symptoms of foodborne illness caused by Bacillus cereus often go unreported, complicating the effectiveness of conventional chemical and physical methods used to inhibit its growth in food production. This challenge, combined with the increasing use of lactic acid bacteria (LAB) in the food industry and consumer preference for minimally processed products, prompted this study. The antibacterial activity of diffusible substances produced by Lactococcus lactis ATCC 11454 against Bacillus cereus NC11143 and Escherichia coli K-12 MG1655 was investigated using a non-contact co-culture model utilising deMann Rogosa and Sharpe broth, with glucose as a carbon source. This study employed plate counting and flow cytometry to assess the impact of these substances on bacterial growth and to analyse their composition and antimicrobial efficacy. The co-culture of Lactococcus lactis ATCC 11454 resulted in the production of a stable antimicrobial peptide, which was heat resistant and acid tolerant. Purification was achieved via ammonium sulphate precipitation and preparative HPLC, yielding a peptide with a molecular mass of 3.3 kDa, with daughter ion fractions similar to nisin A. Antimicrobial activity studies demonstrated that the diffusible substances effectively inhibited B. cereus growth over a period of eight days and exhibited bactericidal activity, killing 99% of the B. cereus cells. Additionally, these substances also inhibited Escherichia coli K-12 MG1655 grown under similar conditions. Comparative analysis revealed that in the co-culture assay, L. lactis produced a 50% higher yield of the antimicrobial peptides compared to pure cultures. Similarly, the specific growth rate of L. lactis was four times higher. With respect to protein purification and concentration, ammonium sulphate precipitation coupled with solid phase extraction was most effective in the purification and concentration of the diffusible substances. The findings provide a basis for utilising bacteriocin-producing strains as a preservation method, offering an alternative to traditional chemical and physical control approaches especially for the food industry.

Tailoring polymer electrolytes with PVA for improved performance in electrical double layer capacitors

In this work, solid polymer electrolytes (SPEs) were synthesized through solution casting, employing polyvinyl alcohol (PVA) as polymer hosts and sodium thiocyanate (NaSCN) for ion transport. Glycerol was incorporated to enhance ionic conduction. The conducted FTIR results establish that glycerol can dissociate more salts. The band associated with SCN anion decreased in intensity and broadened. The ionic conductivity was determined through electrochemical impedance spectroscopy (EIS). The value of ε’ is about twice that of ε’’ value, which is the subject of enormous scientific debate. The AC conductivity spectrum reveals dissimilar regions endorsed to the contributions of electrode polarization and DC conductivity. The ion fraction and its contributions were determined using transference number measurement (TNM), with ion contributions reaching 0.93. The electrolyte exhibited electrochemical stability up to 2.67 V. Charge transfer via Faradaic processes was not observed at the electrode–electrolyte interface, as indicated by CV measurements. The triangular shape of the galvanostatic charge–discharge (GCD) diagram supports capacitive behavior rather than redox reactions, with a specific capacitance of 40F/g. The regular power and energy densities of the electric double-layer capacitors (EDLCs) were estimated as 1255.2 W/kg and 5.5 Wh/kg, respectively, over 1,500 cycles.

Nonlinear saturation of the ion flow driven ion sound instability in a finite length plasma

The saturation mechanism and nonlinear evolution of the ion sound instability driven by the subsonic ion flow in a finite length plasma are studied by a one-dimensional hybrid model considering kinetic ions and Boltzmann electrons. Three regimes of the instability nonlinear behavior are identified as a function of the frequency of the ion-neutral charge exchange (CX) collision fcoll. In the first (collisionless-alike) regime when the CX frequency is low, the instability is saturated by ions trapping in wave potentials leading to the formation of phase space vortexes (PSVs). One of the PSVs subsequently expands and becomes system long in the steady state. The transition to the second (medium) regime occurs when fcoll≳vp/d, where vp is the PSV expansion velocity and d is the system length. In the second regime, CX collisions convert fraction of beam ions into slow ions that can be trapped in potentials of small scale ion sound eigenmodes fluctuations. The trapping of slow ions results in the formation of a chain of small scale PSVs and the disruption of the establishment of the single system long PSV. In the third (collision-dominated) regime when fcoll≳γ (γ is the instability growth rate), CX collisions transform all beam ions into slow ions and the instability is thereby eliminated.

The Background Interstellar Medium as Observed from Off-order Low-resolution Spitzer-IRS Spectra

Spitzer “hidden” observations of the background are used to construct a catalog of 4090 spectra and examine the signature of polycyclic aromatic hydrocarbon (PAH) molecules and their connection to extinction by dust. A strong positive correlation is recovered between WISE12, E(B − V), and the 11.2 μm PAH band. For 0.06 ≤ E(B − V) ≤ 5.0, correlations of the 6.2, 11.2, and 12.7 μm PAH band are positive with E(B − V). Three dust temperature regimes are revealed. Correlations with WISE12 are well constrained and that with 12.7/11.2 is flat. Decomposition with the NASA Ames PAH IR Spectroscopic Database reveals a tentative positive correlation between the 6.2/11.2 and the PAH ionization fraction, while that with 12.7/11.2 is slightly negative, suggesting PAH structural changes. The relation with PAH size and 6.2/11.2 is negative, while that with 12.7/11.2 is positive. Averaging spectra into five E(B − V) and three T dust bins shows an evolution in PAH emission and variations in 12.7/11.2. Database-fits show an increase in f i and the PAH ionization parameter γ, but a more stable large PAH fraction. While the largest γs are associated with the highest T dust, there is no one-to-one correlation. The analysis is hampered by low-quality data at short wavelengths. There are indications that PAHs in the more-diffuse backgrounds behave differently from those in the general interstellar medium. However, they are often still associated with larger scale filamentary cloud-like structures. The spectra and auxiliary data have been made available through the Ames Background Interstellar Medium Spectral Catalog and may guide JWST programs.

Measurements of F1‐ Region Ionosphere State Variables at Arecibo Through Quasi Height‐Independent Exhaustive Fittings of the Incoherent Scatter Ion‐Line Spectra

AbstractWe discuss an exhaustive search approach to fit the incoherent scatter spectrum (ISS) in the F1‐region for molecular ion fraction (fm), ion temperature (Ti), and electron temperature (Te). The commonly used “full profile” approach for F1‐region measurements parameterizes the molecular ion fraction as a function of altitude and fits all the related heights for the state variables. In our approach, we fit the ISS at each height for fm, Ti, Te, and ion velocity (Vi) independently. Our exhaustive search method finds all the major local minima at each altitude. Although a parameterized function is used to guide the algorithm in finding the best solution, the fitting parameters retain their local characteristics. Despite that fitting fm, Ti, and Te without constraints requires Doppler shift to be accurately determined and the ISS signal‐to‐noise ratio higher than the full‐profile method, simulations show that Ti, Te, and fm can be recovered within a few percent accuracy with a moderate signal‐to‐noise ratio. We apply the exhaustive search approach to the Arecibo high‐resolution incoherent scatter radar data taken on 13 September 2014. The derived ion and electron temperatures are sensitive enough to reveal thermosphere gravity waves commonly seen in the electron density previously. Our method is more robust than previous height‐independent fitting methods. Comparison with another Arecibo program indicates our results are likely more accurate. Simultaneous high‐resolution measurements of Ti, Te, fm, Vi, and electron concentration (Ne) in our approach open new opportunities for synergistic studies of the F1‐region dynamics and chemistry.

Experimental and numerical investigation of the Doppler-shifted resonance condition for high frequency Alfvén eigenmodes on ASDEX Upgrade

Abstract The Doppler-shifted resonance condition for high frequency Alfvénic eigenmodes has been extensively studied on ASDEX Upgrade in the presence of one or a combination of two neutral beam injected (NBI) fast ion populations. In general, only centrally deposited NBI sources drive these modes, while off-axis sources globally stabilize the mode activity. For the case of a single central NBI source, the observed trend is: the highest frequency modes are driven by the lowest energy and lowest pitch angle NBI sources, in line with the expectation from the Doppler-shifted resonance condition. The expected mode frequencies are determined analytically from the two-fluid cold plasma dispersion relation and the most unstable frequency relation, while the mode growth rates are estimated using the fast ion slowing down distribution functions from the ASCOT code. The overall mode frequency trend in a source-to-source variation is tracked, although a systematic overestimate of ∼1 MHz is observed. Possible causes of this overestimate include the finite size of the resonant fast ion drift orbit and non-linear effects such as mode sideband formation. Alternatively, the expected mode frequencies are determined by tracking the growth rate maxima trajectories, this method improves the agreement with the experimentally measured values. A combination of two central mode-driving NBI sources results in the suppression of the mode driven by the lowest energy and the lowest pitch angle NBI source. Computing the analytically expected mode frequency following the method outlined above, again, generally tracks the experimentally observed trend. The mode’s Alfvénic nature allows for a practical application to track the core hydrogen fraction by following the mode frequency changes in response to a varying ion mass density. Such application is demonstrated in a discharge where the average ion mass is varied from ∼2m p to ∼1.5m p (where m p is the proton mass) via a hydrogen puff in a deuterium plasma, in the presence of a strong mode activity. The expected mode frequency changes are computed from the existence of the resonance condition, and the values track the measured results with an offset of ∼0.5 MHz. Overall, the results suggest an intriguing possibility to monitor and control the D-T ion fraction in the core of a fusion reactor in real time using a non-invasive diagnostic.

Electrochemical properties of plasticized PVA-based electrolyte inserted with alumina nanoparticles for EDLC application with enhanced dielectric constant

In the current study, the role of alumina nanoparticles was examined in the electrochemical and device performance of PVA-based electrolytes. The NaSCN was used as a cation provider for the host electrolyte, and the glycerol plasticizers were used to enhance conductivity and flexibility. The ratio of salt and plasticizer was fixed, while nanoparticles were varied. The results of impedance AC conductivity confirm that 3 wt% of alumina insertion results in high DC conductivity, which is sufficient for electrochemical device application. Electrode polarization region and plateau area are clearly distinguished in AC spectra. The study of the Dielectric constant reveals that charge storage is maximum at 3 wt% of alumina. The dielectric constant values are about twice the dielectric loss value, which is the topic of immense scientific discussion. The contribution of ion fraction was found to be 0.94, which is excellent compared to the negligible contribution of electrons, which is about 0.05. Electrochemical stability is an additional crucial factor and was found to be 2.47 V. To identify any Redox or non-Redox phenomena occurring in the electrical double-layer capacitor (EDLC) cyclic voltammetry (CV) as the simplest analysis method has been carried out on the sample having the highest DC value. A leaf-like form of the CV plot was noticed at high scan rates, while a rectangular shape was identified at low scan rates. The charge-discharge shape is almost close to the ideal triangular pattern. The discharge part was used to calculate critical EDLC device parameters such as ESR, efficiency, specific capacitance power density, and energy density over 2000 cycles. Low ESR (below 60 Ω) and stable efficiency (almost 100 %) of the device results in high capacitance (≈87 F/g), power density (2978 Wh/kg), and energy density (12.86 W kg−1). The results established that nan-fillers alongside plasticizer is crucial to deliver EDLC devices with improved performances.

Galaxy–Absorber Association in the Epoch of Reionization: Galactic Population Luminosity Distribution for Different Absorbers at 10 ≥ z ≥ 5.5

How do galaxies of different luminosities contribute to the metal absorber populations of varying species and strength? We present our analysis of the predicted metal contributions from galaxies as observed in quasar absorption line spectra during the end of the epoch of reionization (10 ≥ z ≥ 5.5). This was done by implementing on-the-fly particle tracking into the latest Technicolor Dawn simulation and then linking C ii, C iv, Si ii, Si iv, O i, and Mg ii absorbers to host galaxies in postprocessing. We define the host galaxy luminosity distribution (HGLD) as the rest-frame ultraviolet luminosity distribution of galaxies contributing ions to an absorber, weighted by the fractional contribution, and compute its dependence on ion and absorber strength. The HGLD shape is predicted to be indistinguishable from the field luminosity function, indicating that there is no relationship between the absorber strength or ion and the luminosity of the dominant contributing galaxy. Switching from galaxy luminosity to stellar mass, the predicted host galaxy mass distributions (HGMDs) indicate that more-massive galaxies contribute a higher fraction of metal ions to absorbers of each species, with the HGMDs of stronger absorbers extending out to higher masses. We conclude that the fraction of absorbing metal ions contributed by galaxies increases weakly with stellar mass, but the scatter in luminosity at fixed stellar mass obscures this relationship. For the same reason, we predict that observational analyses of the absorber–galaxy relationship will uncover stronger trends with stellar mass than with luminosity.

Jets from the Upper Scorpius Variable Young Star System 2MASS J16075796-2040087 via KECK/HIRES Spectro-astrometry

2MASS J16075796-2040087 is an ∼5 Myr young star in Upper Sco with evidence for accretion bursts on a timescale of about 15 days and, uncommonly for its age, outflows traced by multicomponent forbidden emission lines (FELs). The accretion bursts may be triggered by a companion at ∼4.6 au. We analyze HIRES spectra optimised for spectro-astrometry to better understand the origin of the several FEL velocity components and determine whether a magnetohydrodynamic (MHD) disk wind is present. The FEL high-velocity component (HVC) traces an asymmetric, bipolar jet ∼700 au long. The jet’s position angle ∼ 277° is not perpendicular to the disk. The lower-velocity emission, classified previously as a disk wind low-velocity component, is found to have more in common with the HVC and overall it is not possible to identify an MHD disk wind component. The spectro-astrometric signal of the low-velocity emission resembles those of jets and its density and ionisation fraction fall into the range of HVCs. We suggest a scenario where the accretion bursts due to the close companion power the jets past the age where such activity ends around most stars. The low-velocity emission here could come from a slow jet launched near the close companion and this emission would be blended with emission from the MHD wind.

Beam energy recovery in Neutral Beam Injections and related simulations

The Neutral Beam Injectors (NBI) will be used to further increase the plasma temperature for the ignition of the fusion reactions in the ITER project. For future applications of electric energy production, the NBI efficiency is crucial. Since the gas neutralizer gives large residual ion fractions of D+ and D-, adequate energy recovery systems may be necessary. Recently a conceptually simple beam energy recovery based on space charge effects has been proposed; it can also work as an ion dump device, with advantages in removing the residual ions with reduced power dissipation. Preliminary simulation results were evidence of that the proposed device can remove all the residual ions by collecting them at very low energy on proper electrodes. In this contribution, further simulations with more accurate space charge calculations are reported to mostly confirm the high residual ion collection efficiency obtained in the preliminary simulations. The simulated operation voltage is also increased from 20 kV to 500 kV in steps. Higher efficiencies require some increase of the collector length, especially at higher operation voltage, as here discussed. Some design detailed features are also updated.

The molecular picture of the local environment in a stable model coacervate.

Complex coacervates play essential roles in various biological processes and applications. Although substantial progress has been made in understanding the molecular interactions driving complex coacervation, the mechanisms stabilizing coacervates against coalescence remain experimentally challenging and not fully elucidated. We recently showed that polydiallyldimethylammonium chloride (PDDA) and adenosine triphosphate (ATP) coacervates stabilize upon their transferto deionized (DI) water. Here, we perform molecular dynamics simulations of PDDA-ATP coacervates in supernatant and DI water, to understand the ion dynamics and structure within stable coacervates. We found that transferring the coacervates to DI water results in an immediate ejection of a significant fraction of small ions (Na+ and Cl-) from the surface of the coacervates to DI water. We also observed a notable reduction in the mobility of thesecounterions incoacervates whenin DI water, both in the cluster-forming and slab simulations, together with a lowered displacement of PDDA and ATP. These results suggest that the initial ejection of the ions from the coacervates in DI water may induce an interfacial skin layer formation, inhibiting further mobility of ionsin the skin layer.