Individual Ions Research Articles

Photoluminescence of high energy xenon ion irradiated magnesium aluminate spinel single crystals

Laser confocal microscopy technique (60 ps laser pulse excitation at 445 nm) and a time-correlated single photon counting (TCSPC) technique have been used to study the photoluminescence (PL) in 152 MeV Xe ion irradiated MgAl2O4 single crystals. It was shown that radiation defects produced by swift xenon ions give rise to broad luminescence band positioned in the 470–800 nm wavelength range. The measurements of the PL decay curves have evidenced that lifetime of defect-related PL signal gradually increases from 6 to 10 ns in 500–620 nm spectral range and decreases with ion fluence increasing. The decrease of the luminescence intensity observed after fluences ∼1013 cm−2 is attributed to overlapping of individual ion track core regions.

Bioaccumulation of trace metal ions in the blue swimmer crab tissues Portunus pelagicus (Linnaeus, 1758) in Bahrain, Arabian Gulf.

The blue swimmer crab, Portunus pelagicus, is an edible abundant crustacean found in many seas around the world, including the Arabian Gulf. In this study, the concentrations of six metal ions in the white and brown meats of P. pelagicus from four sites in Bahrain were determined. P. pelagicus was found to accumulate Zn2+ and Cu2+ higher than other metal ions in the order of Zn2+ > Cu2+ > Cd2+ > Ni2+ > Cr3+, while Pb2+ was not detected. The overall average concentrations of Zn2+, Cu2+, Cr3+, Ni2+, and Cd2+ in white meat were 236.2, 69.5, 0.109, 0.159, and 0.273 mg/kg, while in brown meat, they were 235.4, 199.2, 0.133, 1.25, and 4.87 mg/kg based on dry weight, respectively. Concentrations of Pb2+ and Cd2+ were safe according to Bahrain's and European Commission guidelines. The estimated weekly intake (EWI) values of Zn2+, Cu2+, Pb2+, and Cd2+ via consumption of crab's white meat (edible tissue) were 102.1, 30.1, 0.042, and 0.12 µg/kg/week, respectively, which are far lower than the maximum recommended values established by the FAO/WHO. The hazard quotient (HQ) values of individual trace metal ions and the synergistic effects of total trace metal ion (hazard index) were below 1, indicating that there is no potential health risk on the consumption of crab edible tissues (white meat). However, elevated levels of Cd2+ (0.05-1.73 mg/kg wet weight) in the brown meat (hepatopancreas) were detected. The female P. pelagicus accumulated high levels of Zn2+ and Cu2+ in the white meat, as well as Cu2+ in the brown meat compared to males. Additionally, it was found that Cu2+ and Cd2+ were significantly higher (p < 0.05) in brown meat compared to white meat. Higher concentrations (p < 0.05) of Zn2+, Cu2+, and Cd2+ were observed in crabs collected from sites that have harsher environmental conditions.

High temperature oxides for selective absorption of thermal radiation

Most high melting temperature oxides are translucent in the visible-infrared region characteristic of the blackbody thermal radiation at high temperatures. Consequently, over this broad-band spectral region, the “thermal radiation window”, they do not absorb thermal radiation. Translucent oxides, such as the zirconates, can be extensively doped with rare-earth (RE) ions (Nd, Sm, Er, Dy, Yb) to achieve selective spectral absorption, and the doped oxides exhibit low thermal conductivity. The optical absorption bands are due to electronic transitions between electronic states associated with the rare-earth ions and are relatively insensitive to other rare-earth ions within the same compound. Therefore, mixed rare-earth compounds exhibit optical absorption characteristic of the sum of the individual ions’ absorptions. By contrast, the thermal conductivity of the RE zirconates is shown to be relatively independent of composition suggesting that their optical properties in the thermal radiation window regions can be modified without affecting their thermal conduction properties.

Effects of inorganic ions on autotrophic denitrification by Thiobacillus denitrificans and on heterotrophic denitrification by an enrichment culture

Salinity of nitrate-laden wastewaters, such as those produced by metal industries, tanneries, and wet flue gas cleaning systems may affect their treatment by denitrification. Salt inhibition of denitrification has been reported, while impacts of individual ions remain poorly understood whilst being relevant for wastewaters where often the concentration of a single ion rather than the salts varies. The aim of this study was to determine the inhibition by inorganic ions (Na+, Cl−, SO42− and K+) commonly present in saline wastewaters on denitrification and reveal its potential for the treatment of such waste streams, like those produced by NOx-SOx removal scrubbers. The inhibitory effects were investigated for both heterotrophic (enrichment culture) and autotrophic (T. denitrificans) denitrification in batch assays, by using NaCl, Na2SO4, KCl and K2SO4 salts at increasing concentrations. The half inhibition concentrations (IC50) of Na+ (as NaCl), Na+ (as Na2SO4) and Cl− (as KCl) were: 4.3 ± 0.3, 7.9 ± 0.5 and 5.2 ± 0.3 g/L for heterotrophic, and 1–2.5, 2.5–5 and 4.1 ± 0.3 g/L for autotrophic denitrification, respectively. Heterotrophic denitrification was completely inhibited at 20 g/L Na+ (as NaCl), 30 g/L Na+ (as Na2SO4) and 30 g/L Cl− (as KCl), while autotrophic at 8 g/L Na+ (as NaCl), 10 g/L Na+ (as Na2SO4) and 15 g/L Cl− (as KCl). In both cases, Cl− addition had the most important role in decreasing denitrification rate, while Na+ at 1 g/L stimulated autotrophic denitrification but rapidly inhibited the rate at higher concentrations. Nitrite reduction was less inhibited by the ions than nitrate reduction and both the osmotic pressure and the toxicity of the single ions played key roles in the overall inhibition of denitrification. Eventually, both autotrophic and heterotrophic denitrification showed potential for the treatment of a saline wastewater from a NOx-SO2 removal scrubber from a pulp mill.

A guided light system for agile individual addressing of Ba+ qubits with 10−4 level intensity crosstalk

Trapped ions are one of the leading platforms for quantum information processing, exhibiting the highest gate and measurement fidelities of all contending hardware. In order to realize a universal quantum computer with trapped ions, independent and parallel control over the state of each qubit is necessary. The manipulation of individual qubit states in an ion chain via stimulated Raman transitions generally requires light focused on individual ions. In this manuscript, we present a novel, guided-light individual addressing system for hyperfine Ba+ qubits. The system takes advantage of laser-written waveguide technology, enabled by the atomic structure of Ba+, allowing the use of visible light to drive Raman transitions. Such waveguides define the spatial mode of light, suppressing aberrations that would have otherwise accumulated in a free-space optics set up. As a result, we demonstrate a nearest neighbor relative intensity crosstalk on the order of 10−4, without any active aberration compensation. This is comparable to or better than other previous demonstrations of individual addressing. At the same time, our modular approach provides independent and agile control over the amplitude, frequency, and phase of each channel; combining the strengths of previous implementations.

Single-electron spin resonance detection by microwave photon counting.

Electron spin resonance spectroscopy is the method of choice for characterizing paramagnetic impurities, with applications ranging from chemistry to quantum computing1,2, but it gives access only to ensemble-averaged quantities owing to its limited signal-to-noise ratio. Single-electron spin sensitivity has, however, been reached using spin-dependent photoluminescence3-5, transport measurements6-9 and scanning-probe techniques10-12. These methods are system-specific or sensitive only in a small detection volume13,14, so that practical single-spin detection remains an open challenge. Here, we demonstrate single-electron magnetic resonance by spin fluorescence detection15, using a microwave photon counter at millikelvin temperatures16. We detect individual paramagnetic erbium ions in a scheelite crystal coupled to a high-quality-factor planar superconducting resonator to enhance their radiative decay rate17, with a signal-to-noise ratio of 1.9 in one second integration time. The fluorescence signal shows anti-bunching, proving that it comes from individual emitters. Coherence times up to 3 ms are measured, limited by the spin radiative lifetime. The method has the potential to be applied to arbitrary paramagnetic species with long enough non-radiative relaxation times, and allows single-spin detection in a volume as large as the resonator magnetic mode volume (approximately 10 μm3 in the present experiment), orders of magnitude larger than other single-spin detection techniques. As such, it may find applications in magnetic resonance and quantum computing.

Hi'CT: a pixel sensor-based device for ion tomography

Carbon ions, commonly referred to as particle therapy, have become increasingly popular in the last decade. Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion radiotherapy. Range uncertainty is currently the largest contributor to dose uncertainty in normal tissues, leading to the use of safety margins in treatment planning. One potential method is the direct relative stopping measurement (RSP) with ions. Heavy-ion CT (Hi′CT), a compact segmented full digital tomography detector using monolithic active pixel sensors, was designed and evaluated using a 430 MeV/u high-energy carbon ion pencil beam in Geant4. The precise position of the individual carbon ion track can be recorded and reconstructed using a 30 μm × 30 μm small pixel pitch size. Two types of customized image reconstruction algorithms were developed, and their performances were evaluated using three different modules of CATPHAN 600-series phantoms. The RSP measurement accuracy of the tracking algorithm for different types of materials in the CTP404 module was less than 1%. In terms of spatial resolution, the tracking algorithm could achieve a 20% modulation transfer function normalization value of CTP528 imaging results at 5 lp/cm, which is significantly better than that of the fast imaging algorithm (3 lp/cm). The density resolution obtained using the tracking algorithm of the customized CTP515 was approximately 10.5%. In conclusion, a compact digital Hi'CT system was designed, and its nominal performance was evaluated in a simulation. The RSP resolution and image quality provide potential feasibility for scanning most parts of an adult body or pediatric patient, particularly for head and neck tumor treatment.

A cryogenic ion trap for single molecule vibrational spectroscopy.

We report on an ion trapping system for performing a novel form of cryogenic messenger spectroscopy with single molecule sensitivity. The system features a cryogenic radio-frequency ion trap loaded with single analyte molecules via a quadrupole mass filter. We demonstrate the ability to controllably attach inert gas particles to buffer gas cooled, trapped molecular ions. Sympathetic cooling by co-trapped, laser cooled 88Sr+ further reduces the translational temperature of trapped molecules to the millikelvin regime. We verify the presence of cryogenic "tags" via non-destructive optical mass spectrometry and selectively remove these adducts by resonantly driving vibrational transitions in the tagged molecular ions. This enables us to derive the vibrational spectrum of a single analyte molecule from the frequency dependence of the tag detachment rate. We have demonstrated these capabilities by measuring transitions in the C-H stretching region for single cationic fragments of both indole (C8H7N) and 1,3-benzodioxole (C6H4O2CH2). These capabilities are not reliant on a specific molecular level structure and thus constitute a general, non-destructive method for vibrational spectroscopy of individual molecular ions.

Top-Down Analysis of Supercharged Proteins Using Collision-, Electron-, and Photon-Based Activation Methods.

The impact of supercharging on the fragmentation patterns of six proteins, ubiquitin, cytochrome c, staph nuclease, myoglobin, dihydrofolate reductase, and carbonic anhydrase, was investigated for five activation methods, HCD, ETD, EThcD, 213 nm UVPD, and 193 nm UVPD under denaturing conditions. Changes in sequence coverage, alterations in the number and abundance of preferential cleavages (N-terminal to proline, C-terminal to aspartic or glutamic acid, adjacent to aromatic residues), and changes in individual fragment ion abundances were evaluated. Large decreases in sequence coverage were observed upon supercharging of proteins activated by HCD, whereas modest gains were observed for ETD. Minimal changes in sequence coverage were observed when using EThcD, 213 nm UVPD, and 193 nm UVPD, all of which tended to display the highest sequence coverages of the activation methods. Specific preferential backbone cleavage sites were increasingly enhanced for all proteins in supercharged states for all activation methods, particularly for HCD, 213 nm UVPD, and 193 nm UVPD. Even if large gains in sequence coverages were not apparent for the highest charge states, supercharging consistently led to at least a few new backbone cleavage sites for ETD, EThcD, 213 nm UVPD, and 193 nm UVPD for all proteins.

Isobaric heat capacities of eleven ionic liquids containing imidazolium, pyrrolidinium, pyridinium, sulfonium, and ammonium cations with cyano-based and trifluoromethanesulfonyl-based type anions. Experimental and prediction

The isobaric heat capacities were determined using a differential scanning calorimeter with the Tian-Calvet type heat flux detector for selected eleven ionic liquids, i.e., butyltriethylammonium bis(trifluoromethylsulfonyl)imide [N2224][NTf2], diethylmethylsulfonium bis(trifluoromethylsulfonyl)imide [S122][NTf2], 1-(2-methoxyethyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C1C2(OC1)im][NTf2], 1-hexyl-3-methylimidazolium tricyanomethanide [C1C6im][C(CN)3], 1-methyl-3-octylimidazolium tricyanomethanide [C1C8im][C(CN)3], 1-methyl-3-propylimidazolium trifluoromethanesulfonate [C1C3im][CF3SO3] 1-butyl-1-methylpyrrolidinium dicyanamide [C1C4pyr][N(CN)2], 1-butyl-1-methylpyrrolidinium tricyanomethanide [C1C4pyr][C(CN)3], 1-butyl-2-methylpyridinium bis(trifluoromethylsulfonyl)imide [C12 C4py][NTf2], 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide [C13 C4py][NTf2], and 1-butyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide [C14 C4py][NTf2]. The influence of the position (2, 3, or 4) of the methyl substituent on the value of the heat capacity in the last three structural isomers is observed in the case of position 2 only; isomers with methyl substituent in positions 3 and 4 are indistinguishable. The experimental data determined at atmospheric pressure 98.0 kPa in the temperature range 293.15 – 323.15 K were also compared with values estimated by two predictive models based on the group contribution method and model based on the contribution of the individual ions. The predictions are in relatively good accordance with experimental data, regardless of ionic liquids with [N(CN)2]– and [C(CN)3]– anions and [S122]+ cation. Furthermore, the simplicity of these models does not regard arene substitution patterns, and only a single generalized result has been obtained for pyridinium ionic liquids.

Dynamic Energy Measurements in Charge Detection Mass Spectrometry Eliminate Adverse Effects of Ion-Ion Interactions.

Ion-ion interactions in charge detection mass spectrometers that use electrostatic traps to measure masses of individual ions have not been reported previously, although ion trajectory simulations have shown that these types of interactions affect ion energies and thereby degrade measurement performance. Here, examples of interactions between simultaneously trapped ions that have masses ranging from ca. 2 to 350 MDa and ca. 100 to 1000 charges are studied in detail using a dynamic measurement method that makes it possible to track the evolution of the mass, charge, and energy of individual ions over their trapping lifetimes. Signals from ions that have similar oscillation frequencies can have overlapping spectral leakage artifacts that result in slightly increased uncertainties in the mass determination, but these effects can be mitigated by the careful choice of parameters used in the short-time Fourier transform analysis. Energy transfers between physically interacting ions are also observed and quantified with individual ion energy measurement resolution as high as ∼950. The mass and charge of interacting ions do not change, and their corresponding measurement uncertainties are equivalent to ions that do not undergo physical interactions. Simultaneous trapping of multiple ions in CDMS can greatly decrease the acquisition time necessary to accumulate a statistically meaningful number of individual ion measurements. These results demonstrate that while ion-ion interactions can occur when multiple ions are trapped, they have negligible effects on mass accuracy when using the dynamic measurement method.

Photoswitchable Rhodamine‐Based Multianalyte Sensors for Metal Ion Detection

AbstractWe have developed three azobenzene‐core‐based molecular systems decorated with different numbers of rhodamine units as photoswitchable multianalyte sensors. Exploiting the ring‐opening of the spirolactam part of the rhodamine unit, the resulting fluorescence response, and modulation of it through the photoswitching of azobenzene by light, we utilized them in the detection of multiple metal ions (Fe3+, Fe2+, Sn2+ and Al3+). The binding sites, stoichiometry, binding constants, fluorescent lifetimes and limit of detection (LOD) for each probe have been deduced using appropriate spectroscopic techniques. The limit of detection (LOD) of 5 a, 5 b and 5 c for Fe3+ are found to be 4.2×10−7±7.8×10−9 M, 2.2×10−7±4.6×10−9 M and 1.2×10−7±4.6×10−9 M, respectively. The fluorescence response of the metal‐chelated complex can be manipulated effectively by employing the photoswitching ability of azobenzene that makes them useful as chemosensors for various individual metal ions.

A Note on Conservative Mixing: Implications for Selecting Salinity-Transport Model Constituents in the San Francisco Estuary

The deviation of specific electrical conductance (EC) from conservative mixing behavior is well-established in the scientific literature. This principle is based on the observation that, as salt concentration in a water sample increases, the mobility of individual ions in the sample decreases, and thus their ability to conduct electricity decreases. Despite this fact, some commonly used models for salinity transport in the San Francisco Estuary (estuary) utilize EC as a primary simulation constituent, treating it as a conservative quantity. Such a modeling approach has likely been followed to exploit the wide availability of EC data for model calibration and validation, and to obviate the need to translate between EC and salinity in a domain characterized by multiple source waters with varying ionic make-ups. Arguably, this approach provides a reasonable trade-off between data translation error and model simulation error. In this paper, we critically evaluate this approach, employing an extensive salinity data set that includes measurements of EC and major ion concentrations in the estuary. We demonstrate and quantify EC deviation from steady-state, conservative mixing behavior; review the conservative mixing behavior of three bulk salinity measures (practical salinity, ionic strength, and limiting equivalent conductance); and evaluate their source-dependent correlations with EC in the estuary. We find limiting equivalent conductance—a value that assumes uninhibited mobility among individual ions in a water sample—to be an attractive alternative for salinity transport in the estuary. In addition to being a conservative quantity, it is consistently correlated with EC in the estuary’s dominant source waters, and thus addresses concerns related to data-translation error. We conclude this paper discussing pros and cons of adopting various salinity-transport model constituents.

FEATURES OF THE SCANDIUM IONS INTERACTION WITH THE INTERPOLYMER SYSTEM LEWATIT CNP LF (H+ ) - AB-17-8 (OH- ) SYSTEM

The sorption of the interpolymer systems on the basis on Lewatit CNP LF and AB-17-8 industrial ion exchanges in the relation to scandium ions has been studied. The purpose of this research has been to study the sorption capacity of the interpolymer system “Lewatit CNP LF:AV-17-8” in relation to scandium ions. Methodology. To calculate the sorption parameters, the optical density of the solutions has been measured on the Jenway-6305 spectrophotometer. The obtained results have shown that the maximum sorption degree of the “Lewatit CNP LF:AV-17-8” interpolymer systems during 48 h of interaction has occurred in the molar ratios (3:3, 2:4 and 1:5) of polymers, the sorption degrees have been 26.4%; 27.9% and 26%, respectively. As can be seen, the value of the sorption degree is maximum at the ratio of 2:4. The value of the sorption degree in this ratio is higher by 32.5% and 28.5%, respectively, as compared with the degree of sorption of individual ion exchangers Lewatit CNP LF (6:0) and AV-17-8 (0:6).The highest values of the polymer chain binding degree after 48 h with scandium ions in the interpolymer system “Lewatit CNP LF:AV-17-8” for the ratios of 3:3; 2:4 and 1:5 have been 4.87%, 5.25% and 5.01%, respectively. The values of the polymer chain binding degree of the individual Lewatit CNPLF (6:0) and AV-17-8 (0:6) ion exchangers, after 48 h have been 3.68% and 4.26%, respectively. Conclusion. The obtained results have shown that the mutual activation of ion exchange resin the interpolymer system leads to a significant increase in their sorption capacity.

#2696 IN SILICO ELECTROPHYSIOLOGICAL STUDY REVEALS TAMSULOSIN MEDIATE URETER SMOOTH MUSCLE CONTRACTION BY INCREASING POTASSIUM CURRENT

Abstract Background and Aims Tamsulosin is a common α1-AR antagonist that is prescribed to patients with acute kidney stone episodes [Scotland et al., 2021]. According to accumulated experimental data, abnormal peristaltic contraction of the ureter smooth muscle (USM) causes acute kidney stone episodes [Lang et al., 2006]. Intracellular electrical activities like membrane depolarization and action potentials play important roles in modulating the USM contraction by releasing intracellular calcium from the sarcoplasmic reticulum. Therefore, an electrophysiological study will be helpful to assess the USM cell's electrical activities and in diagnosing abnormal USM contraction. Transient potassium channels (KA) are prevalent in different systems and hold immense importance for maintaining/performing selective electrophysiological functions. The present study investigates the altered electrophysiological characteristics of the USM cell because of the induction of Tamsulosin doses. Method The single isolated USM cell comprises several voltage-gated ion channels, such as two voltage-gated calcium (T-type, and L-type) channels, one voltage-gated fast potassium (KA) channel, one calcium-dependent large conductance potassium channel, and an HCN channel. The individual ion channel currents and the membrane potential are recorded by utilizing both the voltage clamp and current clamp protocols. A Tamsulosin drug (0.5 mg) model for the KA channel is introduced by multiplying the maximal conductance of the KA channel with a scaling factor between 0 and 1 to mimic the drug concentration. Statistical analysis protocols are evaluated for analytical purposes. Results In this in silico electrophysiological model, the resting membrane potential is maintained at −75 mV, as this value is cited by various experimental studies. The ionic concentrations and biophysical parameters for all ion channels are varied in the physiological ranges. Under the voltage clamp protocol, the voltage steps are increased from a holding potential of −80 mV to −10 mV with a 10 mV of step voltage. In Figure 1, the red and blue solid lines represent recorded outward KA current from the isolated USM cell under both control and applied Tamsulosin dose conditions. Figure 1 reveals that the KA current is elevated after the application of the Tamsulosin drug regarding all step voltages. As a result, the total outward current is elevated and the USM action potential duration is shortened. It is also observed that the steady-state activation curve of the KA channel is shifted to more negative after applying Tamsulosin. The USM cell is electrically less excitable with the Tamsulosin. Conclusion This first in-silico study reveals the KA ionic current, which plays a major role in coordinating ureteral contractions, is altered due to Tamsulosin. It implies that the pharmacological maneuver of Tamsulosin is substantially beneficial to treat dysfunctional peristalsis by reducing the symptoms and installation complexities from the ureteral stents procedure.

A Coupled Volatility and Molecular Composition Based Source Apportionment of Atmospheric Organic Aerosol

We apply non-negative matrix factorization (NNMF) to molecular composition and volatility measurements of ambient sub-micrometer particles made using a high-resolution time of flight chemical ionization mass spectrometer (HRToF-CIMS) equipped with a custom filter inlet for gases and aerosols (FIGAERO) as part of the Southern Oxidant and Aerosol Study (SOAS). The resulting factors have a representative thermogram, which carries information on the factor volatility and unique weights for individual ions corresponding to molecular components of measured organic aerosol (OA). These properties and the diurnal patterns of factor weights are used to assign a specific source to each factor. With no a priori information used as input, the routine produces a set of factors with spectra that align well with those previously determined from several laboratory chamber experiments. The factorization routine gains relevance and separation of OA composition when using resolved thermograms as input rather than integrated thermogram time series. Of the seven factors produced by NNMF using the thermogram data, three are attributed to monoterpene-derived OA with extremely low, low, and semivolatile volatility. These three factors together represent 68% of the total organic aerosol mass examined, consistent with previous studies using a spectral basis set. Additionally, two factors were sourced to isoprene chemistry, one representing IEPOX-derived SOA, and the other relating to other oxidation products exhibiting relatively low volatility. The two isoprene-related factors account for 22% of OA mass. Notably absent is a category exclusively capturing the behavior of particulate organic nitrates (PON), which may be consistent with the relatively low local concentrations of PON observed and points to limitations of factorization to fully characterize OA. However, NNMF applied to the volatility and molecular level information from the FIGAERO HRToF-CIMS can resolve dominant precursors and chemical properties of ambient OA components with minimal assumptions.

Natural attenuation of uranium in a fluvial Wetland: Importance of hydrology and speciation

A nuclear fuel fabrication facility released 43,500 kg of uranium into a riparian wetland located on the Savannah River Site between 1955 and 1988. Studies were undertaken to evaluate hydrological and geochemical processes influencing uranium accumulation in the wetland. Gamma-radiation-mapping surveys were conducted by systematically walking over the contaminated wetland with backpacks equipped with global positioning systems and NaI gamma detectors. Based on maps compiled from >700,000 gamma spectra and eight sediment uranium depth profiles, it was determined that 94% of the released uranium remained in the wetland. The uranium in the wetland is concentrated in five multi-hectare areas along the stream, accounting for ∼11% of the land area adjacent to the stream. While land type (upland or wetland) and topography provided a reasonable first approximation of where much of the uranium was deposited, hydrological watershed modeling revealed that the stream velocity was especially slow through many of the hot spots. Using autoradiography combined with SEM/EDX measurements of contaminated sediments, surprisingly few hot particles were detected. Instead, uranium was evenly distributed throughout the sampled sediment, suggesting that dissolved uranium had bound to sediment particles that became suspended and later deposited in low energy (low flow velocity) portions of the stream. EXAFS suggested that U atoms were present as individual ions in disordered complexes within the sediment. Furthermore, linear combination analyses suggested that the predominant component of the U(VI) was adsorbed to sediment minerals (∼70%) and a minor component (∼30%) was associated with organic matter phases. These studies show that wetlands can be extraordinarily effective at binding and retaining uranium, thereby providing a natural barrier to the transport of uranium out of a watershed. However, significant anthropogenic or climatic changes to wetlands, such as those associated with flooding, forest fires, or land use, may disrupt the complex hydrological and biogeochemical balance necessary to maintain long-term immobilization of uranium.

Orbitrap-Based Mass and Charge Analysis of Single Molecules.

Native mass spectrometry is nowadays widely used for determining the mass of intact proteins and their noncovalent biomolecular assemblies. While this technology performs well in the mass determination of monodisperse protein assemblies, more real-life heterogeneous protein complexes can pose a significant challenge. Factors such as co-occurring stoichiometries, subcomplexes, and/or post-translational modifications, may especially hamper mass analysis by obfuscating the charge state inferencing that is fundamental to the technique. Moreover, these mass analyses typically require measurement of several million molecules to generate an analyzable mass spectrum, limiting its sensitivity. In 2012, we introduced an Orbitrap-based mass analyzer with extended mass range (EMR) and demonstrated that it could be used to obtain not only high-resolution mass spectra of large protein macromolecular assemblies, but we also showed that single ions generated from these assemblies provided sufficient image current to induce a measurable charge-related signal. Based on these observations, we and others further optimized the experimental conditions necessary for single ion measurements, which led in 2020 to the introduction of single-molecule Orbitrap-based charge detection mass spectrometry (Orbitrap-based CDMS). The introduction of these single molecule approaches has led to the fruition of various innovative lines of research. For example, tracking the behavior of individual macromolecular ions inside the Orbitrap mass analyzer provides unique, fundamental insights into mechanisms of ion dephasing and demonstrated the (astonishingly high) stability of high mass ions. Such fundamental information will help to further optimize the Orbitrap mass analyzer. As another example, the circumvention of traditional charge state inferencing enables Orbitrap-based CDMS to extract mass information from even extremely heterogeneous proteins and protein assemblies (e.g., glycoprotein assemblies, cargo-containing nanoparticles) via single molecule detection, reaching beyond the capabilities of earlier approaches. We so far demonstrated the power of Orbitrap-based CDMS applied to a variety of fascinating systems, assessing for instance the cargo load of recombinant AAV-based gene delivery vectors, the buildup of immune-complexes involved in complement activation, and quite accurate masses of highly glycosylated proteins, such as the SARS-CoV-2 spike trimer proteins. With such widespread applications, the next objective is to make Orbitrap-based CDMS more mainstream, whereby we still will seek to further advance the boundaries in sensitivity and mass resolving power.

Metastability and fragmentation of the OCS3+ states produced by S 2p double Auger decay.

The metastability and the dissociation processes of the OCS3+ states produced by the S 2p double Auger decay of OCS are investigated by multi-electron-ion coincidence spectroscopy using a magnetic bottle electron spectrometer. The spectra of the OCS3+ states filtered for the production of individual ions are derived by four-fold (or five-fold) coincidence among three electrons and a product ion (or two ions). The ground OCS3+ state is confirmed to be metastable in the 10 µs regime. The OCS3+ states relevant to the individual channels of two- and three-body dissociations are clarified.

One-step leaching mechanism for total elemental recovery from spent lithium-ion batteries utilizing ethylene diamine tetraacetic acid

A process capable of leaching full component valuable metals including Ni, Co, Mn, and Li from spent lithium-ion batteries (LIBs) without additional reducing agents has been proposed. As a strong chelating organic acid, ethylene diamine tetraacetic acid (EDTA) is suitable for recovering up to 99.9 % of each metal element under optimal conditions of EDTA concentration of 0.5 M, liquid-solid ratio of 30:1 mL g−1, the temperature of 353 K, and leaching duration of 2 h. Kinetic analysis shows that the entire leaching process is controlled by the chemical reaction, accompanied by the apparent activation energy of 56.6 kJ mol−1 for Ni, 68.2 kJ mol−1 for Co, 49.5 kJ mol−1 for Mn, and 53.0 kJ mol−1 for Li, respectively. The thermodynamic mechanism indicates that EDTA acts as a proton chelating agent and Fe/Al exhibits a synergistic reduction effect during leaching process. In addition, the whole process is divided into three stages, where the behavior of each substance is specified. The individual ions in the leachate are separated by precipitation with different reagents and the filtrate can be recycled for the next stage of leaching, which also provides a novel approach for an industrial one-step leaching process.