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H/D isotope separation faces critical challenges in terms of separation efficiency and cost. This study presents a novel, scalable fabrication of centimeter-scale, defect-free vermiculite monolayer membranes via a modified Langmuir–Blodgett method. These membranes demonstrate H/D separation efficiency comparable to monolayer graphene, promising cost-effective applications. [ABSTRACT FROM AUTHOR]

It is possible that an isotope separation cascade uses two types of separators having different separation factors. Arrangement of the separators in the cascade may affect its separation performance and, therefore, finding the appropriate arrangement is of interest in practice. Six arrangements are considered, four of which have the schemes of a single cascade with four segments, and two have the schemes of a double cascade with two segments on each cascade. Based on the segmented Q-cascade, different separators are installed in different segments. Taking the cascade relative total flow as the objective of optimization, analyses are performed on the relations of the relative total flow with separation factors and the ratio of the two separators. The results show that different arrangements result in different performances, which can be significant. The double cascade scheme is the best. [ABSTRACT FROM AUTHOR]

A comparison of the efficiencies of the optimum mixing and nonmixing (ideal) cascades comprising stages, the coefficients of separation of a mixture at which are dependent on their parameters, has been performed. It was established that an optimized mixing cascade can have a smaller number of centrifuges, as compared to that of a nonmixing cascade, the separation capacity of whose stages deviate from the optimum one by 1–10%. For an optimum mixing cascade, this deviation is smaller, which can be explained by that the requirement for the fulfillment of the nonmixing condition at the joints of flows in such a cascade narrows the area of search for the parameters of the cascade and thus excludes more effective variants of solving the separation problem. [ABSTRACT FROM AUTHOR]

A review of the results obtained by a group of researchers from National Research Nuclear University MEPhI in the course of computer simulation of the gas dynamics and separation of isotopic mixtures in gas centrifuges with ultrafast rotor rotation is presented. The physics of the obtained regularities, as well as unsolved problems are discussed. [ABSTRACT FROM AUTHOR]

Nuclear fusion is a phenomenon that is well known within the nuclear physics community as a viable option for alternative energy as many natural gases and fossil fuels are phased out of commercial use. Deuterium and tritium fusion reactions are currently the leading candidates for nuclear fusion, with a major limiting factor being a means to produce tritium on an industrial scale. Lithium-6 is a well-known isotope that can produce tritium and helium following a fission reaction with a neutron. Unfortunately, the lithium-6 enrichment methods are limited to the COLEX process, which leaves behind an alarming amount of mercury waste as a potential environmental contaminant. Deep eutectic solvents are believed to be a potential alternative to lithium isotope separations due to the ease of generation, in addition to the minimum environmental waste generated when these solvents are employed. Previous studies have suggested that deep eutectic solvents are capable of separating lithium isotopes by utilizing a 2-thenoyltrifluoroacetone and trioctylphosphine oxide system that can biphasically react with a buffered solution containing lithium chloride. This system displays a separation factor of 1.068, which when compared to the 1.054 separation within the COLEX process, makes it a potential candidate for lithium-6/7 separation. Within this study, we investigate this system in comparison to two newly synthesized deep eutectic solvents and find that within these acetylacetone-based systems, little isotopic separation is observed. We investigate these systems both experimentally and computationally, showing the different lithium cation affinities, in addition to proposing how the electron-donating or -withdrawing nature can influence these systems. [ABSTRACT FROM AUTHOR]

Adsorptive separation of Gd3+ ions was evaluated using DOWEX-50×8 ion exchange resin. It has shown a maximum adsorption capacity of 228.50 mg/g at optimum pH 5 and room temperature. Separation of Gd isotopes was investigated using packed bed columns of the resin in displacement chromatographic techniques where 1,2-cyclohexanedinitrilotetraacetic acid was used as displacer in the mobile phase. Isotopic analysis data by using MC‒ICP‒MS confirmed that the front end of the Gd adsorption band exhibited enrichment of the heavier isotope (160Gd), while the lighter isotopes (157Gd and 155Gd) were concentrated at the rear end of the stationary phase. [ABSTRACT FROM AUTHOR]

The Liquid Phase Catalytic Exchange (LPCE) process plays a pivotal role in the separation of hydrogen isotopes, particularly in applications such as tritium removal in heavy water reactors. Effective separation is crucial for maintaining reactor safety and efficiency. In this study, the optimal operating conditions for the LPCE process were determined through orthogonal experiments and validated in different hydrogen isotope systems. The experiments investigated key operational parameters, including the filling ratio of catalyst to packing (FR), operating temperature (T), superficial gas velocity (V), and gas-to-liquid flow rate ratio (λ), using a robust L16 orthogonal experiment design. The results indicated that V and FR had the most significant effects on the height equivalent to a theoretical plate (HETP), while λ exhibited the greatest impact on dedeuterization efficiency (DE). The optimal conditions obtained were V = 0.1 m/s, FR = 1:2, T = 70 °C, and λ = 2.5. Furthermore, the reproducibility of the optimal conditions was verified in LPCE columns with varying diameters (1.5 cm, 2.5 cm, 4.5 cm). Additionally, the findings were applied to both H-D and D-T separation systems, demonstrating consistency in mass transfer efficiency and validating the applicability of the optimal conditions in different hydrogen isotope separations. This research provides critical insights for optimizing tritium removal systems in heavy water reactors, contributing to enhanced reactor safety and performance. [ABSTRACT FROM AUTHOR]

Ice-core water isotopes contain valuable information on past climate changes. However, such information can be altered by post-depositional processing after snow deposition. Atmosphere–snow water vapor exchange is one such process, but its influence remains poorly constrained. Here we constructed a box model to quantify the atmosphere–snow water vapor exchange fluxes and the associated isotope effects at sites with low snow accumulation rates, where the effects of atmosphere–snow water vapor exchange are suspected to be large. The model reproduced the observed diurnal variations in δ18O , δD , and deuterium excess (d-excess) in water vapor at Dome C, East Antarctica. According to the same model framework, we found that under average summer clear-sky conditions, atmosphere–snow water vapor exchange at Dome A can cause diurnal variations in atmospheric water vapor δ18O and δD of 4.8 ‰ ± 2.6 ‰ and 29 ‰ ± 19 ‰, with corresponding diurnal variations in surface snow δ18O and δD of 0.80 ‰ ± 0.35 ‰ and 1.6 ‰ ± 2.7 ‰. The modeled results under summer cloudy conditions display similar patterns to those under clear-sky conditions but with much smaller magnitudes of diurnal variations. However, under winter conditions at Dome A, the model predicts few to no diurnal changes in snow isotopes, consistent with the stable boundary condition in winter that inhibits effective vapor exchange between the atmosphere and snow. In addition, after 24 h and continuous simulations of 11 d, the model predicts significant enrichments in snow isotopes under summer conditions, while in winter, the depletions also accumulate after each 24 h simulation but with a much smaller magnitude of change compared to the results from summer simulations. If the modeled snow isotope enrichments in summer conditions and the depletions in winter conditions represent the general situation at Dome A, this likely suggests that atmosphere–snow water vapor exchange tends to increase snow isotope seasonality, and the annual net effect would be overall enrichments in snow isotopes since the effects in summer appear to be greater than those in winter. This trend will need to be further explored in the future with more comprehensive model studies and/or field observations and experiments. [ABSTRACT FROM AUTHOR]

Magmatic-hydrothermal processes associated with granitic rocks are crucial for magma evolution and rare metal enrichment. This study presents Rb isotope compositions (δ87Rb) for whole rocks and Rb-enriched minerals (biotite and K-feldspar) from the Qitianling granite pluton in South China, which hosts one of the world's largest Sn-ore deposits. This pluton comprises three stages of granitic evolution, including less evolved initial (the first stage) granites to highly differentiated Sn-rich granites in subsequent stages (the second and third stages). The δ87Rb values of whole rocks and K-feldspar vary slightly from −0.34 ‰ to −0.03 ‰ and −0.43 ‰ to −0.09 ‰, respectively. In contrast, biotites show a systematic variation from the first stage (−0.55 ‰ to −0.28 ‰) to the second (0.21 ‰ to 0.39 ‰) and third stage (−0.20 ‰ to −0.05 ‰), which is influenced by magmatic fluids. Significantly, biotites from the second stage exhibit extremely high Rb concentrations exceeding 7600 μg/g, more than 4 times higher than the other two stages, indicating additional enrichment processes beyond fractional crystallization. Furthermore, δ87Rb values of biotites correlate positively with concentrations of various rare metal elements (Rb, Sn, Li, Cs, Nb, and W), suggesting the involvement of magmatic fluids enriched in heavy Rb isotope (87Rb) and fluid-mobile rare metals. Biotite, capable of accommodating these metals within the interlayer or octahedral sites, thus serves as a reliable recorder for the migration and enrichment of rare metals through magmatic-hydrothermal processes. Collectively, our findings demonstrate the potential utility of Rb isotopes of biotite as a robust tracer for magmatic-hydrothermal processes and rare metal mineralization in granitic systems. [ABSTRACT FROM AUTHOR]

Utilizing the anti-Zeno effect, we demonstrate that the resonances of ultracold molecular interactions can be selectively controlled by modulating the energy levels of molecules with a dynamic magnetic field. We show numerically that the inelastic scattering cross section of the selected isotopic molecules in the mixed isotopic molecular gas can be boosted for 2–3 orders of magnitude by modulation of Zeeman splittings. The mechanism of the resonant anti-Zeno effect in the ultracold scattering is based on matching the spectral modulation function of the magnetic field with the Floquet-engineered resonance of the molecular collision. The resulting insight provides a recipe to implement resonant anti-Zeno effect in control of molecular interactions, such as the selection of reaction channels between molecules involving shape and Feshbach resonances, and external field-assisted separation of isotopes. [ABSTRACT FROM AUTHOR]

This review provides a summary of the existing literature on a crucial raw material for the production of isotopically pure semiconductors, which are essential for the development of second-generation quantum systems. Silicon-28-tetrafluoride (28SiF4) is used as an educt for several isotope-engineered chemicals, such as silane-28 (28SiH4) and silicon-28-trichloride (28SiHCl3), which are needed in the pursuit of various quantum technologies. We are exploring the entire chain from the synthesis of 28SiF4 to quantum applications. This includes the chemical properties of SiF4, isotopic enrichment, conversion to silanes, conversion to bulk 28Si and thin films, the physical properties of 28Si (spin neutrality, thermal conductivity, optical properties), and the applications in quantum computing, photonics, and quantum sensing techniques. [ABSTRACT FROM AUTHOR]

Stable water isotopologs can add valuable information to the understanding of evaporation processes. The identification of the evaporation front from isotopolog concentration depth profiles under very dry soil conditions is of particular interest. We compared two different models that describe isotopolog transport in a drying unsaturated porous medium: SiSPAT‐Isotope and DuMux. In DuMux, the medium can dry out completely whereas in SiSPAT‐Isotope, drying is limited to the residual water saturation. We evaluated the impact of residual water saturation on simulated isotopic concentration. For a low residual water saturation, both models simulated similar isotopolog concentrations. For high residual water saturation, SiSPAT‐Isotope simulated considerably lower concentrations than DuMux. This is attributed to the buffering of changes in isotopolog concentrations by the residual water in SiSPAT‐Isotope and an additional enrichment due to evaporation of residual water in DuMux. Additionally, we present a comparison between high‐frequency experimental data and model simulations. We found that diffusive transport processes in the laminar boundary layer and in the dried‐out surface soil layer need to be represented correctly to reproduce the observed downward movement of the evaporation front and the associated peak of isotopolog enrichment. Artificially increasing the boundary layer thickness to reproduce a decrease in evaporation rate leads to incorrect simulation of the location of the evaporation front and isotopolog concentration profile. Core Ideas: Isotopolog fractionation in the unsaturated zone was studied.A comparison between high‐frequency experimental data of isotope enrichment and model simulations was carried out.Effects of drying below residual water content and of boundary conditions on isotope concentrations were analyzed.The evaporation front depth was estimated by using the depth of the concentration gradient maximum. [ABSTRACT FROM AUTHOR]

Separation of hydrogen isotopes (D2/H2) attracts wide interest due to its important applications, such as nuclear fusion. Kinetic quantum sieving‐induced separation over tailored nanoporous solids is a promising method; however, the dynamic separation often shows a transient feature, thus a low D2/H2 selectivity even at temperature below 50 K. Herein, we selectively enriched the accessible quantum sieving (AQS) sites in two‐dimensional carbons by chemically growing a pore‐narrowing layer. The spatial density of such AQS sites is 8.5 times higher than that of commercial carbon molecular sieves. The kinetic selectivity of D2/H2 reached 4.6 at 77 K. Column breakthrough experiments revealed that the dynamic D2/H2 separation was enhanced by such a nanopore design. Aspen simulation indicated that D2 was enriched to 93.1% within 11 pressure swing adsorption cycles with a 1% D2/99% H2 mixture as feed. [ABSTRACT FROM AUTHOR]

Coprecipitation facilitates the incorporation of Zn into the lattice of Fe (hydr)oxide, which is a crucial mechanism causing low Zn bioavailability in widespread Zn-deficient soils. Zn isotopes are a potential indicator of the coprecipitation of Zn and Fe (hydr)oxides in soils. However, the Zn isotope fractionation caused by coprecipitation with amorphous Fe (hydr)oxides (e.g., ferrihydrite) and the impact of environmentally relevant conditions remain unknown. Here, the molecular mechanism and impact factor of Zn isotope fractionation during Zn2+-Fe3+ coprecipitation under natural soil conditions (including different pH values and initial Zn/Fe ratios) were investigated by combining isotope ratio measurements, extended X-ray absorption fine structure (EXAFS) analyses, and density functional theory (DFT) geometry optimization. The results show that aqueous Zn (Zn aq) can be complexed on the ferrihydrite surface (Zn ads) with positive isotope fractionation (Δ66Zn ads–aq = 0.42 ± 0.09 ‰) or directly incorporated into the ferrihydrite lattice with slightly negative isotope fractionation (Δ66Zn stru-aq = −0.08 ± 0.03 ‰). In addition, over time, the surface-complexed Zn can further transform to a layered structure on the surface but exhibits limited Zn isotope fractionation. According to Zn K-edge EXAFS, the Zn isotope fractionation of surface complexation and incorporation of Zn aq are related to the decrease in the Zn–O bond strength in the order surface complexed Zn (R Zn–O = 2.00 Å) > aqueous Zn (R Zn–O = 2.08 Å) > directly incorporated Zn (R Zn–O = 2.06–2.07 Å with slight distortion). The limited Zn isotope fractionation associated with the transformation of Zn ads is related to the reconfiguration of Zn ads during the nucleation of octahedral Zn layer structures. Furthermore, the primary process controlling Zn isotope fractionation is different under varying experimental conditions, leading to distinct Zn isotope fractionation between the bulk solid and solution during Zn–Fe coprecipitation. Low pH values (5.0–6.0) and initial Zn/Fe ratios (0.01–0.02) favor the direct precipitation of Zn aq , resulting in slightly negative Zn isotope fractionation between the bulk solid and solution. In contrast, high pH values (7.0–7.5) and initial Zn/Fe ratios (0.1–0.2) favor surface complexation and the transformation of Zn ads , leading to heavy Zn isotope enrichment in the bulk solid. These findings offer novel insights into the primary mechanism through which Fe (hydr)oxides regulate Zn bioavailability in Zn-deficient soils and provide experimental evidence supporting the potential application of Zn isotopes as an indicator for comprehending the fate of Zn controlled by Fe (hydr)oxides in soils. [ABSTRACT FROM AUTHOR]

The SOLPS‐ITER3.0.8 code with new Grad‐Zhdanov module was applied for predictive modeling of tritium plasma and deuterium‐tritium mixture in tokamak JET. The moderate power scenario of shot JPN #85278 modeled earlier for deuterium plasma was taken as a starting point. Effect of puffing increase, which was applied in experiment, on divertor conditions and inter‐ELM tungsten sputtering for both working gases and on isotope separation in their mixture is analyzed. Both for attached and for semi‐detached outer targets, the tritium plasma shows moderate increase in SOL width compared to deuterium one. The tungsten sputtering at the outer target in the inter‐ELM period for tritium is an order of magnitude bigger than that for deuterium. The D–T separation in the D–T mixture is moderate. [ABSTRACT FROM AUTHOR]

The research progress of porous organic framework materials, represented by metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), used as novel adsorbents in the separation of gas-phase isotope and liquid-phase isotope in recent years is reviewed, the difficulties in the present study are clarified, and the future development trend is prospected, which provides reference for further research on the application of MOFs/COFs in isotope adsorption and separation. [ABSTRACT FROM AUTHOR]

In this study, the objective was to separate cadmium isotopes using the Q-cascade approach. The optimal value of the parameter M* was determined by minimizing the function (∑Lε²0)/2P within the Q-cascade. To overcome computational challenges, the Newton-Raphson solver and direct substitution algorithm were employed to solve the system of nonlinear equations. The direct substitution method was used to provide a suitable initial guess for the Newton-Raphson method. Validation of the developed algorithms using stable cadmium isotopes showed that the value of M* undergoes slight changes with variations in the target isotope concentration in the product and waste streams. For enriching Cd-106 in the product, M* was approximately 108.5, corresponding to the average molar mass of Cd-106 and Cd-111. As the target isotope concentration in the product increases, the number of enrichment stages increases more steeply compared to the number of stripping stages. Similarly, increasing the Cd-116 enrichment in the waste leads to a larger increase in the number of stripping stages compared to enrichment stages. [ABSTRACT FROM AUTHOR]

Loss of slab-derived volatile and fluid-mobile elements (FME) through the forearc may represent a large, unaccounted for flux out of convergent margins. To address volatile recycling through the forearc and potential changes in fluid source from the progressively dehydrating subducting slab, we collected water samples from 44 different cold and thermal (>40 °C) springs on a transect across the outer forearc (∼20–40 km to the subducting slab), forearc (∼40–80 km to the slab), and arc (∼80–120 km to the slab) in Costa Rica. We focused on the heavy halogens (Cl, Br, I), as well as B and Li, given their high fluid mobility and thus limited potential for modification by subsequent fluid-rock interaction. Chlorine, boron, and lithium stable isotope ratios show dramatic ranges from −1.7 to +1.0 ‰ (n = 43), −12.0 to +30.9 ‰ (n = 35), and −2.4 to + 27.5 ‰ (n = 38), respectively, with distinct changes across the transect consistent with a sedimentary pore fluid component in the outer forearc, fluids sourced from dehydration of the slab (sediment and altered oceanic crust) in the forearc, and minimal slab input near the arc. Variations in elemental ratios (Br/Cl, I/Cl, B/Cl, Li/B) across the transect are also largely consistent with evolving FME sources during subduction. Boron isotope ratios in some higher-temperature fluids are modified due to phase separation, whereas, lithium and chlorine isotope ratios are minimally modified. Springs located in the outer forearc along a major fault (Falla Morote) deviate from the consistent across-arc trend and record almost the full range of observed isotopic values. This extreme range in values along the fault likely represents a combination of adsorption/desorption effects, weathering, and mixing with crustal fluids. Mass balance calculations show that up to ∼ 70 % of Cl, ∼50 % of Br, ∼30 % of B, ∼15 % of I, and minimal Li may be recycled through the outer forearc and forearc springs of the Costa Rican margin, therefore fluid emission via springs in global forearc regions are a potentially significant output for FME at convergent margins. [ABSTRACT FROM AUTHOR]

Summary: Daphniphyllum macropodum produces alkaloids that are structurally complex with polycyclic, stereochemically rich carbon skeletons. Understanding how these compounds are formed by the plant may enable exploration of their biological function and bioactivities.We employed multiple metabolomics techniques, including a workflow to annotate compounds in the absence of standards, to compare alkaloid content across plants and tissues.Different alkaloid structural types were found to have distinct distributions between genotypes, between tissues and within tissues. Alkaloid structural types also showed different isotope labelling enrichments that matched their biosynthetic relationships.The work suggests that mevalonate derived 30‐carbon alkaloids are formed in the phloem region before their conversion to 22‐carbon alkaloids which accumulate in the epidermis. This sets the stage for further investigation into the biosynthetic pathway. [ABSTRACT FROM AUTHOR]

A method has been developed to calculate a squared-off cascade with an arbitrary number of external flows by varying the cuts of partial flows of the stages and minimizing the deviations of the calculated feed flows of the stages from specified flows. To minimize the deviations of the flows, a honeybee-colony algorithm ensuring a required accuracy in determining the parameters of the cascade was used. Based on a computational experiment on separation of molybdenum hexafluoride, the high efficiency of the method for concentrating isotopes with an extreme mass number has been shown. [ABSTRACT FROM AUTHOR]

Exploring the contributions of new and old water to runoff during precipitation events in agricultural catchments is essential for understanding runoff generation, solute transport, and soil erosion. The aim of this study was to investigate the variability in the isotopic composition of precipitation and runoff in the 66 ha agricultural catchment in Austria, in the Hydrological Open Air Laboratory (HOAL), in order to compare two isotope hydrograph separation methods. The classical two‐component (IHS) and the ensemble hydrograph separation (EHS) were applied to multiple large events in May–October of 2013–2018 using δ18O and δ2H. The peak flow new water contributions obtained by IHS were compared with the average new water fraction from EHS. The average new water fraction calculated with EHS based on regular weekly sampling was close to zero, which can be explained by the large diffuse groundwater discharge into the stream between the events. When only investigating events with high temporal resolution sampling, the results suggest that EHS provided average new water fractions during peak flows (0.46 ± 0.04 for δ18O, 0.47 ± 0.03 for δ2H) that were close to the averages obtained by IHS (0.47 for δ18O, 0.50 for δ2H). New water fractions tended to be higher for larger rainfall intensities. High peak flow new water fractions could be explained by the agricultural land use and soils with low permeability promoting overland flow generation and by some of the tile drainage systems contributing to the delivery of water. In conclusion, a weekly sampling frequency was not sufficient in the HOAL but instead high‐resolution sampling during events was necessary to estimate the average new water contributions during events. While EHS may be a more robust approach compared to IHS, as it relaxes some of the assumptions of IHS, IHS can provide information on the variability of new water contributions of individual events. [ABSTRACT FROM AUTHOR]

Assimilatory nitrate reduction and methane (CH4) oxidation by bacteria play important roles in carbon (C) and nitrogen (N) biogeochemical cycles. Here, an investigation of enzymatic assimilatory nitrate reduction and CH4 oxidation by Methylobacter sp. YHQ from the wetlands is presented, specifically concentrating on N and oxygen (O) isotope fractionation with various initial nitrate and oxygen concentrations. The N enrichment factors (15εassimilation) increased from 4.2 ± 0.7‰ to 6.9 ±1.3‰ and the O isotope enrichment factors (18εassimilation) increased from 2.7 ± 0.9‰ to 4.7 ± 0.8‰ during nitrate assimilation when initial nitrate concentrations increased from 0.9 mM to 2 mM. Similar 18ε and 15ε values were observed at different oxygen concentrations. The values of 18ε and 15ε provided vital parameters for the assessment of assimilatory nitrate reduction via the Rayleigh equation approach. The ratios of O and N isotope enrichment factors (18ε:15ε)assimilation ranged from 0.64 ± 0.15 to 0.74 ± 0.18 during nitrate assimilation by Methylobacter sp. YHQ with Nas, which were different from (18ε:15ε)assimilation for assimilatory eukaryotic nitrate reductase (eukNR) from literature data. Thus, N and O isotope fractionation could be useful tools to distinguish eukNR from Nas during nitrate assimilation. Additionally, the rates of CH4 oxidation and nitrate reduction were evaluated with a reaction-based kinetic model, and it quantitatively described the enzymatic reactions of nitrate assimilation. Combining dual N-O isotope analysis with kinetic modeling provides new insights into the microbially driven C-N interactions. Highlights: • Effects of nitrate and oxygen concentrations on isotope fractionation were revealed. • The (18ε:15ε)assimilation ratios induced by freshwater bacteria were 0.64 ± 0.15–0.74 ± 0.18. • Dual N-O isotopes are useful approaches for distinguishing Nas from eukNR. • The rates of CH4 oxidation and nitrate reduction can be predicted using a kinetic model. [ABSTRACT FROM AUTHOR]

Shergottite meteorites, classified as depleted, intermediate, or enriched based on incompatible trace elements and specific radiogenic isotope compositions (Sr, Nd, and Hf isotope ratios), point to multiple Martian mantle source regions. The oxygen fugacity (f O 2) of these mantle regions, determined from early crystallizing minerals using the olivine-pyroxene-spinel oxybarometer, appears to correlate with incompatible trace element enrichment and isotope compositions. However, values derived from the vanadium-in-olivine oxybarometer challenge this correlation, hinting at potential biases in oxybarometry or complexities in the redox conditions of the Martian mantle. By analyzing the intermediate shergottite Northwest Africa (NWA) 11043 with various oxybarometers, this study deduced its origin from a reduced mantle source, with an average f O 2 value of −0.77 ± 0.35 relative to the iron-wüstite (IW) buffer. Notably, these values coincide with those of depleted shergottites, which represent the depleted Martian mantle region. This redox similarity between intermediate and depleted shergottites contrasts with earlier notions that postulated intermediate shergottites as a mix of depleted and enriched mantle derivatives. Moreover, intermediate shergottites such as NWA 11043, Elephant Moraine (EETA) 79001A, and Allan Hills (ALH) 77005 display 176Hf/177Hf values akin to those of depleted shergottites, suggesting that intermediate mantle components can be separated from the depleted mantle source at approximately 2.2 Ga based on model age calculations. Therefore, there presents a consistent redox state between mantle magma sources of both intermediate and depleted shergottites since the Hesperian period, while enriched shergottites lean toward more oxidized conditions past source formation. This study prompts a reassessment of conventional theories, emphasizing the nuanced redox evolution of the Martian mantle across distinct mantle source regions and underscoring the complexity of the redox evolution of the Martian mantle. The emergence of chemically diverse mantle reservoirs might predominantly arise from early magma ocean differentiation processes, albeit with inherent oxidation nuances. The differences in f O 2 observed between intermediate and depleted shergottites underscore the need for more in-depth studies to decipher Martian mantle differentiation and evolution. [ABSTRACT FROM AUTHOR]

Facilities equipped with two major types of isotope separators—Isotope Separation On-Line (ISOL) and in-flight separators—have produced many types of unstable nuclei and have provided opportunities to study their exotic properties successfully. Gas-cell systems have been developed for both types of radioactive-ion (RI) facilities, enabling the performance of a great variety of nuclear-spectroscopic measurements by compensating for their respective disadvantages in the production and purification of the RI beams. Although many nuclear-spectroscopic studies have been performed in both types of RI facilities by applying 238 U target (ISOL) or 238 U beam (in-flight), two major unexplored regions remain on the nuclear chart located in the regions of the refractory elements in the vicinity of Z = 73–78 and N = 126 and in the actinide elements. Because it is hard or almost impossible to produce the neutron-rich nuclei, which require specific nuclear reactions for the productions, in these unexplored regions. To access these regions and perform nuclear spectroscopy there, the KEK Isotope Separation System (KISS)—an argon-gas-cell-based laser ion source—has been developed and operated. The gas-cell system at the KISS facility is dedicated to multinucleon transfer (MNT) reactions for producing heavy, neutron-rich nuclei in the unexplored regions. Here, we introduce some of the experimental results and discuss a plan to upgrade the facility to promote further nuclear spectroscopy of the nuclei in the unexplored regions. [ABSTRACT FROM AUTHOR]

Solution nuclear magnetic resonance (NMR) analysis of polysaccharides can provide valuable information not only on their primary structures but also on their conformation, dynamics, and interactions under physiological conditions. One of the main problems is that non‐anomeric 1H signals typically overlap, and this often hinders detailed NMR analysis. Isotope enrichment, such as with 13C and 15N, will add a new dimension to the NMR spectra of polysaccharides, and spectral analysis can be performed with enhanced sensitivity using isolated peaks. For this purpose, here we have prepared uniformly 13C‐ and/or 15N‐labeled chondroitin polysaccharides –4)‐β‐D‐glucuronopyranosyl‐(1–3)‐2‐acetamido‐2‐deoxy‐β‐D‐galactopyranosyl‐(1– with molecular weights in the range from 310 to 460 k by bacterial fermentation. The enrichment ratios for 13C and 15N were 98.9 and 99.8%, respectively, based on the mass spectrometric analysis of the constituent chondroitin disaccharides. 1H and 13C NMR signals were assigned mainly based on HSQC and 13C‐detection experiments including INADEQUATE, HETCOR, and HETCOR‐TOCSY. The carbonyl carbon signal of the N‐acetyl‐β‐D‐galactosamine residue was unambiguously distinguished from the C6 carbon of the β‐D‐glucuronic acid residue by the observation of 13C peak splitting due to 1JCN coupling in 13C‐ and 15N‐labeled chondroitin. The T2* and T1 were measured and indicate that both rigid and mobile sites are present in the long sequence of chondroitin. The conformation, dynamics, and interactions of chondroitin and its derivatives will be further analyzed based on the results obtained in this study. [ABSTRACT FROM AUTHOR]

The paper presents calculations of the two-stage separation of silicon isotopes in Q-cascade models. Feed flow profiles are obtained for Q-cascades, and the concentration distribution by stages is determined for silicon isotopes. It is shown that three highly-enriched (>99%) products can be obtained at a 35 g/s feed flow, namely: 32.31 g/s 28Si, 1.61 g/s 29Si, and 1.08 g/s 30Si. [ABSTRACT FROM AUTHOR]

The paper presents calculations of the process parameters of the chemical isotope exchange with a thermal flow reversal in the BF3–C6H5OCH3 system and engineering data for rectifying columns for its implementation. It is shown that the calculated parameters are in good agreement with those found the literature. The best engineering data are obtained for rectifying columns intended for the production of enriched (96 wt.% 10B enrichment) boron in the amount of 2 and 4 tons per year. [ABSTRACT FROM AUTHOR]

Copper (Cu) is an important transition metal, and its isotopes have important applications in geology, environmental science, soil science, and other fields. Cu isotope fractionation can occur in many natural processes. However, the mechanism of Cu isotope fractionation in solution/hydrothermal solution systems is not very clear. In this study, the fractionation effects of complexes of Cu(I) and Cu(II) in solution/hydrothermal solution systems were systematically studied by means of an ab initio method based on first principles. In the simulation of an aqueous solution system, the theoretical treatment method used is the "water-droplet" method. The results show that the heavy Cu isotope (65Cu) enrichment capacity of the Cu-bearing complex solutions is greatly affected by the ligand types both for Cu(I) and Cu(II). For Cu(I) complex solutions, the heavy Cu isotope enrichment sequence is [Cu(HS)2]−·(H2O)42 > [Cu(HS)(H2O)]·(H2O)42 ≈ [Cu(HS)(H2S)]·(H2O)42 > [CuCl]·(H2O)42 > [CuCl2]−·(H2O)42 > [CuCl3]2−·(H2O)42. For the aqueous solutions of Cu(II) with an inorganic ligand (such as H2O, OH−, NO3−, SO42− and CN−), the order of heavy Cu isotope enrichment is as follows: [Cu(H2O)6]2+·(H2O)42 > [Cu(NO3)2]·(H2O)42 > [Cu(OH)2]·(H2O)42 > [CuSO4(H2O)3]·(H2O)42 > [CuNO3(H2O)4]+·(H2O)42 > [CuCN]+·(H2O)42. For the Cu(II) complex solutions with a halogen as ligands, the change order of 1000lnβ is [CuCl]+·(H2O)42 > [CuCl2]·(H2O)42 > [CuBr2]·(H2O)42 > [CuCl3]−·(H2O)42. The sequence of 1000lnβ for Cu(II) organic complex aqueous solutions is [Cu(HOC6H4COO)]+·(H2O)42 > [Cu(CH3CH2COO)]+·(H2O)42 > [Cu(COOHCOO)]+·(H2O)42. The calculation also found that for Cu(I) complex aqueous solutions, the difference in Cu isotope fractionation parameters (1000lnβ) between [CuCl2]−·(H2O)42 and [Cu(HS)2]−·(H2O)42 is relatively large. At 100 °C, the 1000lnβ of the two species are 1.14 and 1.55 (‰), respectively. The difference between the two could be reached up to 0.41 (‰). The Cu isotope fractionation parameter obtained with the "water droplet" method is also very different from the results of previous studies, which indicate that the Cu isotope fractionation behavior of the two is similar. At the same time, the exciting discovery is that the enrichment capacity of heavy Cu isotopes is significantly different between Cu(I) complex aqueous solutions and Cu(II) complex aqueous solutions. At 100 °C, the 1000lnβ of 6 Cu(I) complex aqueous solutions and 13 Cu(II) complex aqueous solutions ranged from 0.90 to 1.55 and 2.24 to 3.25(‰), respectively. It also shows that the REDOX reaction has a significant effect on the Cu isotope fractionation, especially in ore-forming fluids. Therefore, the ligand type is a factor that cannot be ignored when considering the mechanism of Cu isotope fractionation in solution/hydrothermal solution systems. Whether the solvation effect of an aqueous solution is considered or not has a great influence on the numerical values of the final Cu isotope fractionation factors. Hence, the solvation effect of an aqueous solution is an essential determinant in the theoretical calculation of the Cu isotope fractionation factors for Cu-bearing complex solutions. [ABSTRACT FROM AUTHOR]

The present investigation explores the transient magnetohydrodynamics gravity‐driven flow of a viscous, incompressible, electrically conducting fluid past a permeable exponentially accelerated vertical plate in the presence of thermal radiation and suction. Due to several applications in different areas, the influence of Hall current, Dufour number, heat source parameter, and chemically reactive species diffusion are vital and are incorporated in the study, which is the novelty of the present work. The model equations are derived and resolved by utilizing an analytical technique called the Laplace transform procedure. Various properties of the flow due to the influence of different vital parameters have been depicted with the help of graphs. The computed gradients of velocity, temperature and concentration are presented in tabular form. The Hall parameter is observed to strengthen the secondary flow while diminishing the primary flow. Dufour number and heat source parameter enhance the fluid temperature and velocity profiles while the heat sink declines them. Enhancement of the acceleration parameter significantly amplifies the primary skin friction coefficient. Suction boosts the heat transport as well as the mass transport rates at the surface of the plate, whereas injection declines them. Further, the Dufour number causes a significant reduction in the Nusselt number and magnitude of the secondary skin friction coefficient. The practical applications of the current research are the design of aircraft, cooling of microchips, Hall accelerators, separation of isotopes and many more. [ABSTRACT FROM AUTHOR]

Marine evaporitic halite, precipitating from the advanced stage of extremely evaporated seawater, is the most common and abundant evaporitic mineral. The extent to which lithium (Li) is incorporated into evaporite halite during geological periods of massive halite deposition, and the mechanisms of incorporation, are both unknown. These are each important, however, for the quantification of the isotope effect of the evaporitic sink on δ 7 Li seawater , and for the potential use of halite as a recorder of seawater δ 7 Li. Here, new experimental data are presented for the Li fractionation factor for halite from an isothermal evaporation experiment (25 ∘C for 100 days) using marine-derived brine. The resultant solids were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to confirm the mineralogy and crystallinity of the product. Our results show that Li isotopes are not constant during the evaporation process implying that there must be a process that fractionates Li isotopes during halite precipitation. We suggest that this results from Li ionic substitution for sodium (Na) in crystalline halite, a scenario supported by ab-initio calculations, but we also show that Li within halite is predominantly present within fluid inclusions. Thus, the Li isotopic composition of halite is controlled by a mixture of Li within the fluid inclusions and Li that is incorporated into the halite crystalline structure. Overall, the brine becomes enriched in Li 7 during evaporation due to the preferential incorporation of Li 6 into chloride precipitates, and the evolution of δ 7 L i brine is controlled by the precipitated mineral assemblage. The theoretical equilibrium fractionation factor 1000ln α mineral − fluid is -7.8▪ for Li-halite (LiN a 26 C l 27) at 25 C ∘ at equilibrium, which is at the lower limit of Li isotope fractionation factors. Rayleigh fractionation models were fitted to the experimental data yielding a fractionation factor of -25▪3▪. The difference in Li isotope fractionation factor between brine and structurally bound Li may result from kinetic fractionation effects. This study presents a scenario highlighting that extensive halite deposits, formed over geological time in environments with relatively high Li concentration, could potentially impact the δ 7 Li values of seawater during that period, and place constraints on their utility as an archive for δ 7 L i seawater. [ABSTRACT FROM AUTHOR]

In earlier quantum chemical calculations of isotope effects, chemical species in the liquid phase were generally treated as existing in the gas phase. In recent years, however, advances in computational programs have made it easier for the self-consistent reaction field (SCRF) method to handle chemical species in the liquid phase, and as a result, it has become easier to apply the SCRF method to isotope effect calculations. This paper concerns the scope of application of the DFT-SCRF method to reversible processes for hydrogen isotope enrichment. It is found that the applicability of the method depends on the type of the intermolecular interaction in the liquid phase and the degree of hydrogen isotope effect (separation factor) on which the process is based. When the magnitude of the isotope effect of the separation system is greater than 10–1, the simple SCRF method is fully applicable; when the magnitude is around 10–2, SCRF with a dimer model, in which the monomer is replaced by a dimer, is applicable for the analysis of the liquid phase with relatively strong intermolecular interactions. Anharmonic correction to the separation factor calculated based on harmonic frequencies may be effective to systems with the liquid phase with weak intermolecular interactions. [ABSTRACT FROM AUTHOR]

AbstractMaterial losses and gains are generally unavoidable in isotope separation cascades because of air leakage into the cascade and chemical reactions of the materials in contact with the process gas. Both losses and gains are incorporated into the well-known Q-cascade theory and can be considered differently for each component. The theory is applied, as an example, to investigating the separation of natural uranium to produce low-enriched uranium of 5% 235U, in which UF6 incurs material losses, generating the light impurity hydrogen fluoride (HF).Two approaches are discussed, one using a carrier gas and another purging the light impurity to prevent the light impurity from exceeding the upper limit in the cascade product end for safe cascade operation. The results show that using carrier gas increases the relative total flow of the cascade, whereas purging the light impurity requires the development of a purging technology. The investigation presents a complicated but real practical scenario, where the components of different physical and chemical properties (some with and without material losses, and some with gains) all appear in the process gas, and demonstrates the applicability of the theory in the study of separation cascades. [ABSTRACT FROM AUTHOR]

The Indian Summer Monsoon (ISM) and meltwater from the Himalayan are the two most important sources of water in the Indian subcontinent. However, the impact of ISM on Himalayan glaciers and subsequent stream hydrology remains largely unknown. To provide new insight into the impact of rainfall on glacial hydrology, here we present hydro‐meteorological and time‐series observations of meltwater stable water isotope compositions from the snout of the Chorabari glacier in the Upper Ganga Basin, Central Himalayas across the ablation season corresponding to 2019. We observe that rainfall events (>2 mm d−1) on the glacier enhance discharge driven by ice meltwater in River Mandakini. Energy balance calculations reveal that one of the drivers behind enhanced ice meltwater contribution could be rain‐induced melting of the glacier where rainfall on the ice surface melts the glacier producing up to 13% of the total discharge at the glacier snout. Further, rainfall on glacier surface have other control on glacial processes—for example, snow metamorphism, ice flow dynamics such as short‐term acceleration in ice speed flow, and reorganization of the englacial and subglacial drainage network—that are poorly studied and needs further investigation. We conclude rainfall events on the glacier have a complex control on mountain hydrology. This study, therefore, provides an interpretative framework that calls for additional assessments of the direct and indirect impact of rainfall in glacial hydrology. Plain Language Summary: Understanding the drivers of elevated ice meltwater runoff in glacier‐fed Himalayan streams is critically important in constraining the role of climate change in glacial hydrology. The conventional thinking of elevated ice meltwater runoff in Himalayan rivers is mainly attributed to global warming. However, in this study, we find that rain events on the glacier are an additional driver of enhanced ice meltwater discharge in the glacier‐fed Himalayan streams. The additional flux of ice meltwater can be explained by the reorganization of the englacial and subglacial drainage network during rainfall events and/or rain‐induced melting of the glacier ice where raindrops falling on the ice surface are releasing sensible and latent heat by englacial cooling and freezing of rain, thereby raising ice temperatures to the melting point, in result, enhanced ice meltwater contributions. As the number of extreme rainfall events and their associated catastrophes has increased in recent decades, the observed causal relationship between ISM and enhanced ice meltwater contributions in the Himalayas is critical to better manage and predict important environmental problems such as floods in the Himalayas. Key Points: An isotope mixing model was developed to quantify the contributions of rain, ice, and snow meltwater to the total river dischargeWe show heavy monsoonal rainfall triggers the melting of glacier ice resulting in enhanced ice meltwater discharge in streamsWe conclude rainfall events have complex controls on glacial hydrology/processes [ABSTRACT FROM AUTHOR]

The boron isotope ratio of seawater (δ11Bsw) is a parameter which must be known to reconstruct palaeo pH and CO2 from boron isotope measurements of marine carbonates. Beyond a few million years ago, δ11Bsw is likely to have been different to modern. Palaeo δ11Bsw can be estimated by simultaneously constraining the vertical gradients in foraminiferal δ11B (Δδ11B) and pH (ΔpH). A number of subtly different techniques have been used to estimate ΔpH in the past, all broadly based on assumptions about vertical gradients in oxygen, and/or carbon, or other carbonate system constraints. In this work we pull together existing data from previous studies, alongside a constraint on the rate of change of δ11Bsw from modeling. We combine this information in an overarching statistical framework called a Gaussian Process. The Gaussian Process technique allows us to bring together data and constraints on the rate of change in δ11Bsw to generate random plausible evolutions of δ11Bsw. We reconstruct δ11Bsw, and by extension palaeo pH, across the last 65Myr using this novel methodology. Reconstructed δ11Bsw is compared to other seawater isotope ratios, namely Sr87/86 ${}^{87/86}\mathrm{S}\mathrm{r}$, Os187/188 ${}^{187/188}\mathrm{O}\mathrm{s}$, and δ7Li, which we also reconstruct with Gaussian Processes. Our method provides a template for incorporation of future δ11Bsw constraints, and a mechanism for propagation of uncertainty in δ11Bsw into future studies. Plain Language Summary: Boron naturally exists in two forms—11B and 10B. Measuring the ratio of these two forms of boron within marine shells allows us to estimate how alkaline the ocean was in the past, which is related to how much carbon dioxide is in the atmosphere. Before we can do this calculation though, we need to know some other parameters, one of which is the relative abundance of the two forms of boron in the ocean at the time (which we call δ11Bsw). Preexisting studies have estimated δ11Bsw at particular times, and here we combine them to generate a full reconstruction across the last 65 million years, accounting for uncertainties. Our reconstruction is informed by limiting the rate at which δ11Bsw can change, based on model simulations. We provide a set of plausible evolutions of δ11Bsw which can be used in future work when calculating past ocean pH. Key Points: We reconstruct the temporal evolution of seawater isotope ratios of boron, strontium, lithium, and osmium over the last 65 million yearsThe evolution of seawater boron isotope ratio shows similarity to the evolution of strontium, lithium and osmium isotope ratiosRandomly drawn, smooth time series are provided for use in uncertainty propagation in calculation of palaeo pH [ABSTRACT FROM AUTHOR]

Methane release from marine sediments strongly influences the local seafloor environment and ecosystems, and may impact Earth's climate system. Recent studies revealed anomalous molybdenum (Mo) enrichment in seep sediments, which was linked to methane release events. Marine seep sediments are a potential sink of Mo for the global ocean, while the mechanisms leading to local Mo enrichment are not fully understood. The sediments from a gas hydrate-bearing area of the South China Sea analyzed herein reveal authigenic Mo (Mo auth) contents ranging from 0 and 31.4 µg/g and δ98Mo auth values ranging from 0.18 ‰ to 3.31 ‰. The range of δ98Mo auth values of seep sediments is therefore similar to values of modern iron-rich sediments with low concentrations of dissolved porewater hydrogen sulfide and sediments deposited under weakly euxinic sediments. Among the obtained South China Sea data, the more positive δ98Mo auth values (>ca. 1.5 ‰) are interpreted to reflect diffusion of seawater Mo into the sediment at moderate seepage rates and Mo isotope fractionation during the formation of thiomolybdates in the sulfidic seep environment. The lower δ98Mo auth values (

Nickel isotopes have been employed to trace various processes such as the weathering of mafic and ultramafic rocks, mineral adsorption and co-precipitation, and the metabolism of methanogenic archaea. Nickel isotopes have displayed significant potential for application, regardless of whether the processes occur at high or low temperatures. However, the currently employed nickel isotope separation methods have certain limitations in terms of separation effectiveness, blank contribution, separation efficiency, and cost-effectiveness of the resin used. Therefore, in this study, we have devised a user-friendly three-step chromatographic procedure that relies on the Chelex-100 resin and other resins for the efficient isolation and purification of nickel from a wide array of geological samples. The three resins utilized in this procedure are Chelex-100, AGMP-1M, and AGMP-50. It is worth noting that Chelex-100 has exhibited exceptional performance in eliminating alkali metals, alkaline earth metals, and iron. Following chromatographic separation, the recovery of nickel surpassed 96%, with a procedural blank below 1.2 ng. To evaluate the procedure's effectiveness, we conducted nickel isotope measurements on nine geological reference materials (BCR-2, GSR-3, GSP-2, NOD-A-1, GSMC-1, SGR-1, SDO-1, GSD-5a, and GSD-23) using MC-ICP-MS. The obtained values were consistent with previously published data, confirming the reliability of our results. The findings of our study establish the applicability of the developed separation procedure for nickel isotope analysis in various geological samples. [ABSTRACT FROM AUTHOR]

Based on the fact that many water reservoirs built in headwater catchments receive no water input during dry season, we modified the Craig‐Gordon model and proposed an approach to calculate kinetic fractionation factors in open‐water evaporation taking into account isotopic compositions of precipitation and of lake water, lake volume, and land‐based meteorological data. The approach is centered around the determination of lake water isotope enrichment rate over time during dry periods. We then applied this approach for calculating kinetic fractionation factors, turbulence index, and open‐water evaporation for a small reservoir located in a sub‐tropical monsoonal climate. We found that the kinetic fractionation factors, εK,H and εK,O are, respectively 3.11‰ ± 0.41‰ and 2.50‰ ± 2.15‰, corresponding to the turbulence index of 0.43 ± 0.19. Evaporation rates in open‐water estimated by our approach is 1.55 times of the land‐based evaporation gauged in the nearby meteorological station. Wind speed, represented by turbulence index, is proved as an important climatic factor influencing kinetic fractionation. This study confirms that wind and surface area factors, which have been neglected in several isotope mass balance models, should be included into calculation process. Plain Language Summary: Isotopes are forms of the same element that differ in atomic mass. Water molecules (H2O) have lighter isotopes of H (1H, 16O) and heavier isotopes (2H, 18O). The evaporation of water favors the evaporation of the lighter isotope molecules over heavier isotope, via a process called fractionation. Well defined fractionation factors help determine precisely the degree of water loss that can be expected in an open water system due to evaporation. Such an accurate determination of seasonal evaporation loss would in turn help water managers better understand water resource management, especially in a drought prone area. Today, climate change has increased the intensity and frequency of extreme weather events. Many people in the world now live under water stress conditions. Therefore, a precise determination of evaporation loss in open‐water bodies is necessary to increase population resilience to climate change. This study proposes a straight forward approach to determine kinetic fractionation factors (the others are equilibrium fractionation factors) in a desiccating lake during the dry season and apply them to a sub‐tropical reservoir in Viet Nam. The kinetic fractionation factors are found to be highly dependent on wind speed variability while evaporation loss is more dependent on temperature and humidity. Key Points: A modified Craig‐Gordon model was developed to calculate the kinetic fractionation factor of water isotopic compositions in upland reservoirKinetic fractionation is significantly influenced by wind condition for an upland reservoir in sub‐tropical monsoon climateOpen‐water evaporation rate is re‐evaluated as 1.55 times of the land‐based monitoring data [ABSTRACT FROM AUTHOR]

Subduction zones are critical sites for recycling of Li and B into the mantle. The way of redistribution of Li and B and their isotopes in subduction settings is debated, and there is a lack of detailed studies on Li and B partitioning between minerals of different types of eclogites and the host rocks of the eclogites. We present Li and B concentration data of minerals and Li and B whole-rock isotope data for low-T and high-T eclogites and their phengite schist host rocks from the Changning–Menglian suture zone, SW China. Omphacite controls the Li budget in both the low-T and high-T eclogites. Low-T eclogites have Li and δ7Li values (8.4–27.0 ppm, – 5.5 to + 3.2 ‰) similar to the phengite schists (8.7–27.0 ppm, – 3.8 to + 3.0 ‰), suggesting that Li was added to low-T eclogites from the phengite schists. In contrast, high-T eclogites have much lower δ7Li values (– 13.2 to – 5.8 ‰) than the phengite schists, reflecting prograde loss of Li or exchange with wall rocks characterized by low δ7Li values. Phengite and retrograde amphibole/muscovite are the major B hosts for low-T and high-T eclogites, respectively. The budgets and isotopic compositions of B in eclogites are affected by the infiltration of fluids derived from phengite schists, as indicated by eclogite δ11B values (– 15.1 to – 8.1 ‰) overlapping with the values of the phengite schists (– 22.8 to – 9.5 ‰). Lithium and B in eclogites are hosted in different mineral phases that may have formed at different stages of metamorphism, implying that the contents and isotopic compositions of Li and B may become decoupled during subduction-related fluid-mediated redistribution. We suggest a mineralogical control on the redistribution of Li and B in eclogites during subduction and the exchange of Li and B with the immediate wall rocks. The observed contrasting Li and B isotopic signatures in eclogites are likely caused by a fluid-mediated exchange with different types of wall rocks during both prograde metamorphism and exhumation. [ABSTRACT FROM AUTHOR]

High abundance 6Li and 7Li are essential materials for the nuclear industry. In this article, the lithium isotope separation effect and lithium-ion transport of a "lithium salt aqueous solution (anolyte)‖crown ethers–ionic liquid organic solution‖ammonium chloride aqueous solution (catholyte)" electromigration system with B12C4, B15C5 and B18C6 as phase transfer catalysts were investigated systematically. The results show that separation factors can reach 1.028 (B12C4), 1.024 (B15C5) and 1.011 (B18C6), respectively, when LiCl solution is used as the anolyte. The separation effect mainly originated from interfaces between anolytes and organic solutions, and was less affected by an electric field. The separation effect between organic solution and catholytes was greatly affected by the electric field for B12C4 and B15C5 systems, which converted from 7Li-enrichment to 6Li-enrichment with increased voltage. For the B18C6 system it was less affected. Furthermore, lithium ion transport in B12C4, B15C5 and B18C6 systems was greatly promoted by the electric field, with the Li+ concentration in catholytes of B12C4, B15C5 and B18C6 systems increased from 0.088 mg L−1, 0.286 mg L−1 and 0.778 mg L−1 to 8.321 mg L−1, 7.422 mg L−1 and 4.631 mg L−1 respectively as the voltage increased from 2 V to 16 V. The B12C4 system has been confirmed as the optimal solution considering both the Li+ transport and isotope separation effect. [ABSTRACT FROM AUTHOR]

There are 25 Li-rich geothermal fields (>15 mg/L) are displayed throughout nine geothermal zones in Tibet. The Kawu geothermal system is one of the representative high-enthalpy and Li-rich geothermal systems and is located in the Skaya dome, the Himalayas. Their boiling and hot and cold waters are Cl-HCO3-Na and HCO3-Ca types, respectively. The parent geothermal fluids are characterized by high Na, Cl, B, Si, As, Li, Rb+, Cs+ and F, and the Cl− concentration and enthalpy of the parent geothermal liquid are 515 mg/L and 1,485 J/g, respectively (corresponding to a temperature of 323.5°C). The stable oxygen and hydrogen isotopic compositions of geothermal fluids range from −19.7 to −23.4‰ and −155 to −181.2‰, indicating that the ratio of magmatic water mixed into geothermal fluid is between 11.7% and 19.5%. The lithium content in the geothermal system is high (13.04 to 20.8 ppm), but the δ7Li is relatively low (1.06 to 1.72‰). The high Cl, Li and B contents, constant Cl/Li and Cl/B ratios and low δ7Li indicate that they mainly originate from magmatic fluid, rather than from water rock reaction with the leucogranite and gneiss. While ascending from the reservoirs to the surface, the parent geothermal fluids gradually mixed with the meteoric waters infiltrated via brittle tensional small-scale faults, in turn forming four cooling processes upwelling patterns, i.e. conductive cooling, adiabatic cooling, mixing with cold water, and the combination of these processes. [ABSTRACT FROM AUTHOR]

The splitting of the transition from a discrete to an autoionization state, used in a three-step photoionization scheme of lutetium 5d6s2 2D3/2–5d6s6p –5d6s7s 4D3/2–(53375 cm–1) has been studied. The splitting is proportional to the square root of the intensity, which corresponds to the Autler–Townes effect. [ABSTRACT FROM AUTHOR]

In this study, we used an improved "diffusion cell" method to precisely determine the diffusion-driven kinetic isotope fractionation factors of the Li, K, Rb, Mg, Ca, Sr, and Ba cations in aqueous solutions under room temperature. The obtained isotope fractionation factors (±2σ errors) are, α 7/6Li = 0.996139 ± 0.000140, α 41/39K = 0.998572 ± 0.000072, α 87/85Rb = 0.999333 ± 0.000020, α 26/24Mg = 0.999877 ± 0.000010, α 44/42Ca = 0.999704 ± 0.000010, α 88/86Sr = 0.999781 ± 0.000014, α 138/135Ba = 0.999716 ± 0.000018. The results show that the charge of the cation and the ion-water bond length for the aquo ions are the two predominant factors affecting the mass dependence of isotope fractionation (β factor) during cation diffusion in aqueous solutions. Cations with higher charge numbers and shorter ion-water bond lengths exhibit less kinetic isotope fractionation during diffusion. Therefore, the isotope separation effect during diffusion (or β factor) in fluids is fundamentally controlled by the intensity of ion-water interaction. Weaker ion-water interaction (e.g., lower charge number, longer ion-water bond length) leads to less prominent hydrodynamic behavior for diffusing ions at the molecular level, thus more significant isotope fractionation in bulk solutions, and vice versa. Ions of larger radius would show stronger mass dependence of isotope fractionation (β factor), which can cancel the effect of decreasing relative isotope mass difference for heavier elements, thus kinetic isotope fractionation during diffusion in aqueous solutions remains prominent even for heavy elements such as Rb, Sr, and Ba. The diffusion-driven kinetic isotope fractionation factors measured in this study could provide a useful basis for interpreting specific natural isotopic variability of alkaline and alkaline-earth elements in supergene environments where chemical diffusion takes place. [ABSTRACT FROM AUTHOR]

The behavior of 88Y, 152Eu, 228Ac, 241Am, and 244Cm was studied with 2-thenoyltrifluoroacetone resin with batch uptake, kinetics and column studies. Studies were performed in acetate buffer solutions (pH ~ 2 to ~ 6) and there was high uptake of all isotopes, except 228Ac, at pH > 4.5. The kinetics of uptake were reasonable, although slower for the actinides, and sufficient for column studies. The retention of 88Y, 152Eu, and 241Am on the resin in column studies was demonstrated as well as a reasonable separation of these isotopes from 228Ac. [ABSTRACT FROM AUTHOR]

Pure and composite Cu-Amino-terephthalate MOF has been produced by ultrasound wave to evaluate the adsorption capacity and adsorptive separation of D 2 and H 2 at 77 K up to 1000 mbar. The frameworks are characterized by XRD, SEM, FTIR, ICP, BET, and EDX analysis. Separation studies were performed using idealized adsorption solution theory (IAST) and direct measurements. Isotherm studies showed the data had good agreement with the Langmuir model and the adsorption capacity of deuterium was greater than hydrogen in all samples. Linear Driving Force (LDF) model was applied to investigate the effective diffusion coefficients of deuterium and hydrogen in the frameworks. The LDF model showed hydrogen molecules diffused faster than deuterium molecules in all frameworks. In the adsorption enthalpy studies, there was a slight difference between deuterium and hydrogen adsorption energy. In this regard, Cu-BDC-NH 2 @rGO showed a higher adsorption enthalpy difference compared to Cu-BDC-NH 2. Finally, the D 2 /H 2 selectivity of the composite framework was greater than the pure one. Regarding this matter, the Cu-BDC-NH 2 @rGO MOF showed a maximum selectivity factor of about 2.2 at 77 K and 1000 mbar based on the IAST model. • Preparation and characterization of pure and composite Cu-BDC-NH 2 MOFs. • Explore the effect of graphene content on hydrogen isotope separation. • Investigating the kinetic behavior of hydrogen isotopes in adsorption process. • Investigating the effect of graphene content on hydrogen and deuterium adsorption capacity. [ABSTRACT FROM AUTHOR]

The handling and analysis of gaseous tritium is of interest for hydrogen isotope separation experiments. In this work, we present an easy-to-handle setup for catalytic oxidation to HTO, recovering all of the initially dosed gaseous tritium as determined by LSC, using CuO as a catalyst at a reaction temperature of 900 °C. Aiming to reduce cocktail waste, the LSC determination was downscaled to a microfluidic setup. The performance was evaluated based on the counting efficiency, which was shown to decrease significantly, as the sample volume was reduced to µl amounts, while no changes were observed over a wide range of sample-to-cocktail ratios. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur battery represents an innovative technology for the next generation electrochemical energy storage, and insight into the fundamentals about its electrochemistry is a key to improved battery storage performance. With years of striving efforts, the interpretation of Li−S reaction mechanism has been extended down to a molecular level. Based on our recent work, we propose to re‐examine the Li−S electrochemistry at a (sub)atomic level. Both Li anode and S cathode are made up of mixtures of stable isotopes. Provided with almost the same nucleus structure yet different neutron numbers (and atomic mass), these isotopes could affect the thermodynamic and kinetic parameters of a chemical reaction, and energy storage capability of a Li−S battery. At the cathode, 34S forms stronger S−S bonds and shows higher tendency to react with Li than 32S, so that it helps to improve cathode reaction kinetics. High‐order polysulfide anions based on 34S show more sluggish migration in the ether electrolyte than the 32S‐based counterparts, which accounts for improved cycling stability of battery. Based on the electrochemical isotope effects of S, a conceptual technology for separating isotopes from natural chalcogen elements was introduced and shows a higher separation factor than the conventional methods. [ABSTRACT FROM AUTHOR]

The treatment of tritiated nuclear wastewater is facing greater challenges with the continuous expansion of the nuclear industry. The key to solving the issue of detritium in low-abundance tritium water lies in developing highly efficient and cost-effective hydrogen isotope separation technology. Graphene oxide (GO) membrane separation method exhibits greater potential compared to other existing energy-intensive technologies for the challenging task of hydrogen isotope separation in nuclear wastewater. In recent years, researchers have explored few strategies to enhance the performance of graphene oxide (GO) membranes in hydrogen isotope water treatment, recognizing the current limitations in separation efficiency. In this study, the GO/g-C3N4 composite membrane has been successfully employed for the first time in the separation of hydrogen isotopes in water. A series of GO membranes were prepared and their performances were tested by a self-made experimental device. As a result, the separation performance of the GO membrane was enhanced by the modification with graphitic carbon nitride (g-C3N4). The permeation rate of the GO/g-C3N4 membrane was higher than that of the GO membrane, while maintaining a high separation factor. Our study also demonstrated that this phenomenon can be attributed to the changes in membrane structure at the microscopic scale. The H/D separation factor and the permeate flux of the composite membrane containing g-C3N4 of 6.7% by mass were 1.10 and 7.2 × 10−5 g·min−1·cm−2 are both higher than that of the GO membrane under the same experimental conditions, which is promising for the isotope treatment. [ABSTRACT FROM AUTHOR]

The nuclear shell model was used to investigate the bulk properties of lithium isotopes ( 6,7,8,9,11Li), i.e., the ground state density distributions and C0 and C2 components of charge form factors. The theoretical treatment was based on supposing that the Harmonic-oscillator (HO) potential governs the core nucleons while the valence nucleon(s) move through Hulthen potential. Such assumptions were applied for both stable and exotic lithium isotopes. The HO size parameters (bn and bp), the core radii (rc ) and the attenuation parameters (kn and kp) were fixed to recreate the available empirical size radii for lithium isotopes under study. [ABSTRACT FROM AUTHOR]