Using measurements from the Mars Atmosphere and Volatile EvolutioN mission, we investigate the densities of H+ (nH+ ${n}_{{\mathrm{H}}^{+}}$), O+ (nO+ ${n}_{{\mathrm{O}}^{+}}$), and O2+ (no2+ ...${n}_{{\mathrm{o}}_{2}^{+}}$), respectively, in the Martian magnetotail current sheet. We find that the current sheet when it is closer to the terminator than 0.75 Mars radii is mostly dominated by heavy ions ((nO++no2+ ${n}_{{\mathrm{O}}^{+}}+{n}_{{\mathrm{o}}_{2}^{+}}$)>2 nH+ ${n}_{{\mathrm{H}}^{+}}$), regardless of the variation of the upstream solar wind, but that it is sometimes dominated by H+ (nH+ ${n}_{{\mathrm{H}}^{+}}$ >2(nO++no2+ ${n}_{{\mathrm{O}}^{+}}+{n}_{{\mathrm{o}}_{2}^{+}}$)) at downstream distances exceeding 0.75 Mars radii. The occurrence rate of the dominant H+ weakly increases (and that of the heavy ions decreases) with solar wind density and dynamic pressure. Our results suggest that solar wind protons could enter the Martian tail and may become the dominant ion species in the current sheet, particularly when the solar wind density or dynamic pressure is high.
Plain Language Summary
The current sheet of the Martian magnetotail is a major channel for the escape of planetary ions. The ion composition in the current sheet is essential to our understanding of this escape, as well as the magnetotail plasma dynamics. Our current knowledge, however, is poor. Based on the measurements of the ion density of different species in the current sheet from the Mars Atmosphere and Volatile EvolutioN spacecraft, we report that the current sheets we have surveyed are dominated by either the heavy ions from the planet or H+ (mostly) from the solar wind. We find that the downstream distance and the variation of the upstream solar wind are the two key factors that account for which ion species dominates in the tail current sheet.
Key Points
Current sheets are mostly dominated by heavy ions but are sometimes dominated by H+ at the downstream distance exceeding 0.75 Mars radii
The occurrence rate of current sheets with dominant H+ (heavy ions) weakly increases (decreases) with solar wind density and dynamic pressure
Our results suggest that the dominant H+ in the current sheet could originate from solar wind
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
As pioneering Fe
3
O
4
nanozymes, their explicit peroxidase (POD)-like catalytic mechanism remains elusive. Although many studies have proposed surface Fe
2+
-induced Fenton-like reactions ...accounting for their POD-like activity, few have focused on the internal atomic changes and their contribution to the catalytic reaction. Here we report that Fe
2+
within Fe
3
O
4
can transfer electrons to the surface via the Fe
2+
-O-Fe
3+
chain, regenerating the surface Fe
2+
and enabling a sustained POD-like catalytic reaction. This process usually occurs with the outward migration of excess oxidized Fe
3+
from the lattice, which is a rate-limiting step. After prolonged catalysis, Fe
3
O
4
nanozymes suffer the phase transformation to γ-Fe
2
O
3
with depletable POD-like activity. This self-depleting characteristic of nanozymes with internal atoms involved in electron transfer and ion migration is well validated on lithium iron phosphate nanoparticles. We reveal a neglected issue concerning the necessity of considering both surface and internal atoms when designing, modulating, and applying nanozymes.
We list vacuum wavelengths, energy levels, statistical weights, transition probabilities, and oscillator strengths for permitted resonance spectral lines of all ions of 18 astrophysically important ...elements (H through Si, S, Ar, Ca, Fe). Using a compilation of experimental energy levels, we derived accurate wavelengths for 5599 lines of 1828 ground-term multiplets which have
gf-values calculated in the Opacity Project. We recalculated the Opacity Project multiplet
gf-values to oscillator strengths and transition probabilities of individual lines. For completeness, we added 372 resonance lines of Ne I, Ar I, Fe I, and Fe II ions which are not covered by the Opacity Project. Intercombination and forbidden lines are not included in the present compilation.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In aqueous systems, heavy metal ions, when present in excess than permissible limits, are dangerous for human beings and aquatic life. Heavy metals cannot be degraded. Rather, they accumulate in ...living organisms either directly or through the food chain. Inside the body, metal ions can be converted to more toxic forms or can directly interfere with metabolic processes. As a result of metal toxicity, various disorders and damage due to oxidative stress triggered by metal ions have been witnessed. Toxic effects of metallic pollution coupled with the need of pure water for the survival and sanitation have thus prompted researchers to take every possible step to uphold the quality of water. In this regard, various strategies have been developed for the detection and the removal of metal ions from aqueous systems. Here we review metal-free water and methodologies used for rapid detection at low levels. Also, the application of benign materials and methods for metal removal from aqueous systems is detailed. Electrochemical methods, especially stripping and cyclic voltammetry, are commonly used methods for detection, while adsorption and ion exchange methods are quite effective for removal.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Acid sensing ion channels (ASICs) are proton-gated ion channels that are members of the degenerin/epithelial sodium channel superfamily and are expressed throughout central and peripheral nervous ...systems. ASICs have been implicated in multiple physiological processes and are subject to numerous forms of endogenous and exogenous regulation that include modulation by Ca2+ and Cl- ions. However, the mapping of ion binding sites as well as a structure-based understanding of the mechanisms underlying ionic modulation of ASICs have remained elusive. Here we present ion binding sites of chicken ASIC1a in resting and desensitized states at high and low pH, respectively, determined by anomalous diffraction x-ray crystallography. The acidic pocket serves as a nexus for divalent cation binding at both low and high pH, while we observe divalent cation binding within the central vestibule on the resting channel at high pH only. Moreover, neutralization of residues positioned to coordinate divalent cations via individual and combined Glu to Gln substitutions reduced, but did not extinguish, modulation of proton-dependent gating by Ca2+. Additionally, we demonstrate that anion binding at the canonical thumb domain site is state-dependent and present a previously undetected anion site at the mouth of the extracellular fenestrations on the resting channel. Our results map anion and cation sites on ASICs across multiple functional states, informing possible mechanisms of modulation and providing a blueprint for the design of therapeutics targeting ASICs.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Although solid-state lithium (Li)-metal batteries promise both high energy density and safety, existing solid ion conductors fail to satisfy the rigorous requirements of battery operations. Inorganic ...ion conductors allow fast ion transport, but their rigid and brittle nature prevents good interfacial contact with electrodes. Conversely, polymer ion conductors that are Li-metal-stable usually provide better interfacial compatibility and mechanical tolerance, but typically suffer from inferior ionic conductivity owing to the coupling of the ion transport with the motion of the polymer chains
. Here we report a general strategy for achieving high-performance solid polymer ion conductors by engineering of molecular channels. Through the coordination of copper ions (Cu
) with one-dimensional cellulose nanofibrils, we show that the opening of molecular channels within the normally ion-insulating cellulose enables rapid transport of Li
ions along the polymer chains. In addition to high Li
conductivity (1.5 × 10
siemens per centimetre at room temperature along the molecular chain direction), the Cu
-coordinated cellulose ion conductor also exhibits a high transference number (0.78, compared with 0.2-0.5 in other polymers
) and a wide window of electrochemical stability (0-4.5 volts) that can accommodate both the Li-metal anode and high-voltage cathodes. This one-dimensional ion conductor also allows ion percolation in thick LiFePO
solid-state cathodes for application in batteries with a high energy density. Furthermore, we have verified the universality of this molecular-channel engineering approach with other polymers and cations, achieving similarly high conductivities, with implications that could go beyond safe, high-performance solid-state batteries.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
So far, very few numbers of chemosensors for Cr{sup 3+} ion have been reported. However, the main drawback of reported receptors are the lack of selectivity and other trivalent cations such as Fe{sup ...3+}, Al{sup 3+} and anions like F{sup −} and {sup −}OAc frequently interfere with such assays. This paper present the synthesis, characterization & sensor studies of Schiff base containing naphthalene moiety which selectively detect Cr{sup 3+} ion by chemodosimetric approach. Using FT-IR, {sup 1}H NMR, {sup 13}C NMR and ESI mass spectroscopic techniques the probe was characterized. This receptor exhibit more selectivity and sensitivity towards Cr{sup 3+} than other divalent and trivalent cations like Mn{sup 2+}, Zn{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cd{sup 2+}, Cu{sup 2+}, Hg{sup 2+}, Fe{sup 3+}, and Al{sup 3+} ions. After the addition of chromium ion the receptor get change from yellow to colorless in aqueous medium. But no color change was observed on the addition of other metal ions. Using UV-Vis and PL studies, it was confirmed that the selective hydrolysis of imine group of receptor by Cr{sup 3+} ions takes place with high fluorescence enhancement that is corresponding to 1-naphthylamine. Receptor acts as selective chemodosimeter for Cr{sup 3+} ions with 2:1 stoichiometry and micro molar detection limit. This chemodosimetric approach was applied successfully for bio-imaging of HeLa cells.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Ion beams with energies in the keV regime are widely utilized in solid-state physics, but the ultrafast dynamics triggered by an ion impact onto a solid surface is to date exclusively ...accessible via simulations based on many untested assumptions and model parameters. A possible experimental access rests on the availability of a laser-synchronized ion source delivering sufficiently short ion pulses for time resolved pump–probe experiments. Here, we demonstrate a new miniaturized ion optical bunching setup for the creation of rare gas ion pulses using strong-field femtosecond laser photoionization. Neutral Ar gas atoms at room temperature are intercepted by a 50 fs, 800 nm laser pulse focused to ∼10
μ
m spot size. We demonstrate the generation of monoenergetic 2 keV Ar
+
ion pulses with 180 ps duration (FWHM) at laser peak intensities around 10
14
W cm
−2
and of multiply charged Ar
q
+
ions (
q
= 1–5) at higher laser intensities. The results are in good agreement with detailed ion trajectory simulations, which show that the temporal resolution is essentially limited by the initial (thermal) velocity spread of the generated photo-ions, indicating the possibility to achieve even better time resolution by cooling the gas prior to ionization.
The Concise Guide to PHARMACOLOGY 2017/18 provides concise overviews of the key properties of nearly 1800 human drug targets with an emphasis on selective pharmacology (where available), plus links ...to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide represents approximately 400 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point‐in‐time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.13879/full. Ligand‐gated ion channels are one of the eight major pharmacological targets into which the Guide is divided, with the others being: G protein‐coupled receptors, voltage‐gated ion channels, other ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid‐2017, and supersedes data presented in the 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature Committee of the Union of Basic and Clinical Pharmacology (NC‐IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Mechanotransduction, the conversion of physical forces into biochemical signals, is essential for various physiological processes such as the conscious sensations of touch and hearing, and the ...unconscious sensation of blood flow. Mechanically activated (MA) ion channels have been proposed as sensors of physical force, but the identity of these channels and an understanding of how mechanical force is transduced has remained elusive. A number of recent studies on previously known ion channels along with the identification of novel MA ion channels have greatly transformed our understanding of touch and hearing in both vertebrates and invertebrates. Here, we present an updated review of eukaryotic ion channel families that have been implicated in mechanotransduction processes and evaluate the qualifications of the candidate genes according to specified criteria. We then discuss the proposed gating models for MA ion channels and highlight recent structural studies of mechanosensitive potassium channels.
Mechanically activated (MA) ion channels are structurally diverse sensors required for numerous physiological processes including touch, pain, and hearing. Here, Ranade et al. review eukaryotic MA channel families, and explore the potential mechanisms of how these channels might be gated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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