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At least 253 records · Page 14

Coordinated Cation Transport in Ti 3 C 2 T x MXene Membranes

Membrane nanofiltration is an attractive strategy for the selective recovery of high-demand metals from wastewater and brine. Effective sieving of ions in aqueous environments will require precise control over membranes’ nanochannel size and chemistry. Ti 3 C 2 T x MXene is an environmentally stable 2D material that can be processed into laminar membranes containing nanoscale interlayer spaces. The MXene interlayer environment depends on the ion species and amount of water intercalated between MXene sheets, and it is the major factor governing permeation and selectivity through MXene membranes. Coordinated ion–ion and ion-interlayer dynamics in the presence of complex mixtures can impact ion permeability and selectivity. Herein, we observe strong competitive effects between different cations (Li + , Na + , and Ca 2+ ) in binary mixtures, resulting in reduced selectivity when compared with single-salt permeability ratios. X-ray diffraction, molecular dynamics, and density functional theory simulations support the conclusion that cations with stronger attraction to MXene flakes can preferentially occupy the MXene nanochannels and hinder other ions via charge or size exclusion. In conclusion, elucidation of ion transport behavior in MXene under complex conditions will allow for more rational design of efficient ion-sieving membranes.

2D Materials↗

Multi-messenger dynamic imaging of laser-driven shocks in water using a plasma wakefield accelerator

Understanding dense matter hydrodynamics is critical for predicting plasma behavior in environments relevant to laser-driven inertial confinement fusion. Traditional diagnostic sources face limitations in brightness, spatiotemporal resolution, and in their ability to detect relevant electromagnetic fields. In this work, we present a dual-probe, multi-messenger laser wakefield accelerator platform combining ultrafast X-rays and relativistic electron beams at 1 Hz, to interrogate a free-flowing water target in vacuum, heated by an intense 200 ps laser pulse. This scheme enables high-repetition-rate tracking the evolution of the interaction using both particle types. Betatron X-rays reveal a cylindrically symmetric shock compression morphology assisted by low-density vapor, resembling foam-layer-assisted fusion targets. The synchronized electron beam detects time-evolving electromagnetic fields, uncovering charge separation and ion species differentiation during plasma expansion – phenomena not captured by photons or hydrodynamic simulations. We show that combining both probes provides complementary insights spanning kinetic to hydrodynamic regimes, highlighting the need for hybrid physics models to accurately predict fusion-relevant plasma behavior.

imaging techniques↗

Two-temperature effects in Hall-MHD simulations of the HIT-SI experiment

A two-temperature Hall-magnetohydrodynamic (Hall-MHD) model, which evolves the electron and ion temperatures separately, is implemented in the PSI-Tet 3D MHD code and used to model plasma dynamics in the Helicity Injected Torus–Steady Inductive (HIT-SI) experiment. The two-temperature model is utilized for HIT-SI simulations in both the PSI-Tet and NIMROD codes at a number of different injector frequencies in the 14.5–68.5 kHz range. At all frequencies, the NIMROD two-temperature model results in increased toroidal current, lower chord-averaged density, higher average temperatures, outward radial shift of the current centroid, and axial symmetrization of the current centroid, relative to the single-temperature NIMROD simulations. The two-temperature PSI-Tet model illustrates similar trends, but at high frequency operation, it exhibits lower electron temperature, smaller toroidal current, and decreased axial symmetrization with respect to the single-temperature PSI-Tet model. With all models, average temperatures and toroidal currents increase with the injector frequency. Power balance and heat fluxes to the wall are calculated for the two-temperature PSI-Tet model and illustrate considerable viscous and compressive heating, particularly at high injector frequency. Parameter scans are also presented for artificial diffusivity, wall temperature, and density. Both artificial diffusivity and the density boundary condition significantly modify the plasma density profiles, leading to larger average temperatures, toroidal current, and relative density fluctuations at low densities. As a result, a low density simulation achieves sufficiently high current gain (G > 5) to generate significant volumes of closed flux lasting 1–2 injector periods.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Toward the Discovery of New Elements: Production of Livermorium (𝑍 = 116) with 50 Ti

The 244 Pu ⁢(50 Ti ,𝑥⁢𝑛)⁢ 294−𝑥 Lv reaction was investigated at Lawrence Berkeley National Laboratory’s 88-Inch Cyclotron. The experiment was aimed at the production of a superheavy element with 𝑍 ≥114 by irradiating an actinide target with a beam heavier than 48 Ca. Produced Lv ions were separated from the unwanted beam and nuclear reaction products using the Berkeley Gas-filled Separator and implanted into a newly commissioned focal-plane detector system. Two decay chains were observed and assigned to the decay of 290 Lv . The production cross section was measured to be 𝜎 prod = 0.44($^{+0.58}_{−0.28}$) pb at a center-of-target center-of-mass energy of 220(3) MeV. Furthermore, this represents the first published measurement of the production of a superheavy element near the “island of stability,” with a beam of 50 Ti and is an essential precursor in the pursuit of searching for new elements beyond 𝑍 =118.

36 MATERIALS SCIENCE↗

Dynamical control in a prethermalized molecular ultracold plasma: Local dissipation drives global relaxation

Prethermalization occurs as an important phase in the dynamics of isolated many-body systems when coupled degrees of freedom relax in a subspace separated from a state of complete thermodynamic equilibrium by a gap in energy or other conserved quantity. Slow equilibration from a prethermal phase can localize the dynamics of natural and model systems despite high dimensionality and limited disorder. Here, we report the signature of an enduring prethermal regime of arrested relaxation in the molecular ultracold plasma that forms following the avalanche of a state-selected Rydberg gas of nitric oxide. For a wide range of initial conditions, this system enters a critical phase in which a density of NO + and electrons balances a population of Rydberg molecules. Electron collisions mix orbital angular momentum, scattering Rydberg electrons to states of very high ℓ . The rapid predissociation of molecules in states of low- ℓ purifies this high- ℓ ensemble. The angular momentum barrier that separates NO + ions and electrons creates an extraordinary gap between the plasma states of n ≈ ℓ , with measured n > 200 and penetrating states of ℓ = 0 , 1 , and 2. Evolution to a statistically equilibrated state of N and O atoms cannot occur without Rydberg electron penetration, and this gap blocks relaxation for a millisecond or more. A weak radiofrequency (RF) field drives ℓ -mixing electron collisions that erase this gap, causing wholesale dissipation. Remarkably, a local quantum-state transition promoting an exceedingly small fraction of the molecules in the prethermalized ensemble to a predissociative state also acts with a global effect, driving the entire system to a dissipative equilibrium. Using the Lindblad master equation, we illustrate qualitatively similar dynamics for a toy model of an open quantum system that consists of a localized set of spins on which dissipation acts at a single site as a gateway to equilibrium. Published by the American Physical Society 2025

Wang, Ruoxi↗

Structures of five salt forms of disulfonated monoazo dyes

The structures of five s -block metal salt forms of three disulfonated monoazo dyes are presented. These are poly[di-μ-aqua-diaqua[μ 4 -3,3'-(diazane-1,2-diyl)bis(benzenesulfonato)]disodium(I)], [Na 2 (C 12 H 8 N 2 O 6 S 2 )(H 2 O) 4 ] n , (I), catena -poly[[tetraaquacalcium(II)]-μ-3,3'-(diazane-1,2-diyl)bis(benzenesulfonato)], [Ca(C 12 H 8 N 2 O 6 S 2 )(H 2 O) 4 ] n , (II), catena -poly[[[diaquacalcium(II)]-μ-2-(4-amino-3-sulfonatophenyl)-1-(4-sulfonatophenyl)diazenium] dihydrate], {[Na(C 12 H 10 N 3 O 6 S 2 )(H 2 O) 2 ]·2H 2 O} n , (III), hexaaquamagnesium bis[2-(4-amino-3-sulfonatophenyl)-1-(4-sulfonatophenyl)diazenium] octahydrate, [Mg(H 2 O) 6 ](C 12 H 10 N 3 O 6 S 2 ) 2 ·8H 2 O, (IV), and poly[[{μ 2 -4-[2-(4-amino-2-methyl-5-methoxyphenyl)diazen-1-yl]benzene-1,3-disulfonato}di-μ-aqua-diaquabarium(II)] dihydrate], {[Ba(C 14 H 13 N 3 O 7 S 2 )(H 2 O) 4 ]·2H 2 O} n , (V). Compound (III) is that obtained on crystallizing the commercial dyestuff Acid Yellow 9 [74543-21-8]. The Mg species is a solvent-separated ion-pair structure and the others are all coordination polymers with bonds from the metal atoms to sulfonate groups. Compound (I) is a three-dimensional coordination polymer, (V) is a two-dimensional coordination polymer and both (II) and (III) are one-dimensional coordination polymers. The coordination behaviour of the azo ligands and the water ligands, the dimensionality of the coordination polymers and the overall packing motifs of these five structures are contrasted to those of monosulfonate monoazo congers. It is found that (I) and (II) adopt similar structural types to those of monosulfonate species but that the other three structures do not.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Hydrogen Crossover Flux through Two-Dimensional Nanomaterials

Energy storage and conversion devices require an ion-exchange membrane with high transmission of charge-balancing ions and separation of anode and cathode electrolytes/gases. This ensures optimum device performance. Most conventional membranes suffer huge cross-permeation resulting in low energy efficiency and material degradation. This work investigated hydrogen permeability and proton transmission through membrane electrode assemblies (MEAs) containing a monolayer of hexagonal boron nitride and single-layer and bi-layer graphene in a gas-phase small-scale cell and a liquid cell. Here we found that the hydrogen crossover flux through MEAs with 2D materials was inhibited by at least a factor of 5 compared to the one without. Single-layer graphene and boron nitride enabled high proton transmission, but bi-layer graphene inhibited proton conduction. Defect visualization of 2D materials revealed few atomic-scale defects in graphene. These findings suggest that a monolayer of 2D material may provide good selectivity for energy conversion and storage devices by blocking species crossover while allowing high proton transmission.

2D materials↗

Understanding the Quadrupole Mass Filter and Testing a High-Resolution QMS RGA for ITER

A common type of residual gas analyzer is the quadrupole mass spectrometer. One of the main components within this instrument is a mass filter known as the quadrupole. It is responsible for the selective throughput of the ionized gas particles - by ascending mass number - prior to ion impacts on the analyzer (or detector) surface from which the ion current signal is generated for processing. However, the quadrupole is not fully described in relation to the electric field characteristics and the function as an ion mass separator. This paper describes the basic origins of the electrical design, the intricate assembly criteria, and performance of the quadrupole within the spectrometer. A specialized quadrupole mass spectrometer is part of a configuration for a diagnostic gas analyzer system planned for ITER, a fusion research machine. It has a verified capability, essential as a diagnostic criterion for this reactor project, to successfully deconvolute the mass signals of Helium-4 and deuterium (reactor fuel exhaust gases, separated by only 0.026 atomic mass units), down to a relative three-percent concentration of the former gas. The associated preliminary testing, performed at the Oak Ridge National Laboratory, is also addressed. Finally, one of the key parameters used to express gas concentration, the relative sensitivity factor, will be explained, including an evaluation of dependency on other variables.

Marcus, Chris [ORNL] (ORCID:0000000190139636)↗

Retrofit & Expansion Project at Ultra-High Molecular Weight Polyethylene Plant: Completing a Full Domestic Supply Chain for Lithium-Ion Batteries (Final Scientific and Technical Report)

The UTEC-1 LIBS Retrofit and Expansion Project aimed to retrofit and expand Braskem’s UHMWPE unit in La Porte, TX to produce lithium-ion battery separator (LIBS) grade material and increase capacity. The project sought to strengthen the domestic supply chain for advanced battery manufacturing and reduce reliance on imports. While significant progress was achieved in conceptual design and FEL-2 engineering, strategic realignment and external factors led to project termination prior to FEL-3 and FEED execution.

25 ENERGY STORAGE↗

Separation of traces of metal ions from sodium matrices

Method for isolating metal ion traces from sodium matrices consists of two extractions and an ion exchange step. Extraction is accomplished by using 2-thenoyltrifluoracetone and dithizone followed by cation exchange.

Korkisch, J.↗

Electrorefining process for lunar free metal - Space and terrestrial applications and implications

An electrochemical refining process is proposed for the separation and recovery of principal and trace elements from reduced metallic particles found in lunar soils. A process variation is presented for purification and recovery of chromium and manganese from electrodeposited impure iron available from lunar silicate and other minerals. The process involves anodic dissolution of impure metal and cathodic deposition in divided cells using aqueous chloride solutions. The anolyte is withdrawn and separated using ion exchange techniques.

Waldron, R. D.↗

On the low-lying states of CuO

Self consistent field and correlated wave functions have been computed for the ground and for several low-lying states of CuO. The ground state is X(2)PI and the lowest excited state, at approximately 8,000/cm above X(2)PI, is a previously unidentified 2-sigma(+) state. The separation of these states is compared to that for the similar states of KO and is analysed in terms of integrals between orbitals of the separated free ions. A classification of the states of the molecule based on states of Cu(+) and O(-) which leads to a division into manifolds of states arising from Cu(+) 3d(10) and Cu(+) 3d(9) 4s(1) is considered. It is predicted that the state of the 3d(9) 4s(1) manifold are 10,000 to 30,000/cm above the ground state and assign the observed A2-sigma(+) state at 16,500/cm to this manifold.

Bagus, P. S.↗

Earth's compressional foreshock boundary revisited Observations by the ISEE 1 magnetometer

A 'solar foreshock coordinate' (SFC) system is introduced in which the positions of foreshock components can be collated with a minimum of assumptions about the physical processes involved. Location behind the interplanetary magnetic field (IMF) tangent surface to the bow shock and rotational symmetry around the solar wind flow (X) axis are the only presuppositions. The SFC system has been applied to over 300 observations of the boundary of the ULF compressional waves recorded by ISEE 1's magnetometer in 1978 and 1979. The boundary locations form a coherent pattern in the SFC frame. A selection of those cases for which the cone angle of the IMF was between 40 and 50 deg, corresponding to the average stream angle, yields a least square line whose mapping back to the solar ecliptic coordinates frame has slope of about 85 deg, very close to that of the tangent ULF boundary deduced earlier from more primitive methods with entirely different data sets. The line, being parallel to neither the IMF, the typical reflected beam, nor the shock, cannot be compatible with any model of wave production by beam-solar wind interaction that depends on uniform beam distribution or fixed growth rate. Rather, its tangency suggests the influence of a separate, escaping ion population.

Greenstadt, E. W.↗

Theoretical studies of the first- and second-row transition-metal mono- and dicarbonyl positive ions

Ab initio calculations have been carried out on the first- and second-row transition-metal mono- and dicarbonyl positive ions. The bonding in these systems is discussed in detail. Trends in the series of mono- and dicarbonyl ions and between the first- and second-row transition metals are explained in terms of a dominantly electrostatic bonding interaction and differences in metal ion state separations, ionization potentials, and s and d orbital sizes. Dissociation energies are presented and a detailed comparison is made with experimental data. Where reliable experimental data exists, agreement with the theoretical results is generally good.

Barnes, Leslie A.↗