Ultrafiltration separation of Am(VI)-polyoxometalate from lanthanides.

Partitioning of americium from lanthanides (Ln) present in used nuclear fuel plays a key role in the sustainable development of nuclear energy1-3. This task is extremely challenging because thermodynamically stable Am(III) and Ln(III) ions have nearly identical ionic radii and coordination chemistry. Oxidization of Am(III) to Am(VI) produces AmO22+ ions distinct with Ln(III) ions, which has the potential to facilitate separations in principle. However, the rapid reduction of Am(VI) back to Am(III) by radiolysis products and organic reagents required for the traditional separation protocols including solvent and solid extractions hampers practical redox-based separations. Herein, we report a nanoscale polyoxometalate (POM) cluster with a vacancy site compatible with the selective coordination of hexavalent actinides (238U, 237Np, 242Pu and 243Am) over trivalent lanthanides in nitric acid media. To our knowledge, this cluster is the most stable Am(VI) species in aqueous media observed so far. Ultrafiltration-based separation of nanoscale Am(VI)-POM clusters from hydrated lanthanide ions by commercially available, fine-pored membranes enables the development of a once-through americium/lanthanide separation strategy that is highly efficient and rapid, does not involve any organic components and requires minimal energy input.

Polyvalent s-block elements: A missing link challenges the periodic law of chemistry for the heavy elements.

The Periodic Law of Chemistry is one of the great discoveries in cultural history. Elements behaving chemically similar are empirically merged in groups G of a Periodic Table, each element with G valence electrons per neutral atom, and with upper limit G for the oxidation and valence numbers. Here, we report that among the usually mono- or di-valent s-block elements (G = 1 or 2), the heaviest members (87Fr, 88Ra, 119E, and 120E) with atomic numbers Z = 87, 88, 119, 120 form unusual 5- or 6-valent compounds at ambient conditions. Together with well-reported basic changes of valence at the end of the 6d-series, in the whole 7p-series, and for 5g6f-elements, it indicates that at the bottom of common Periodic Tables, the classic Periodic Law is not as straightforward as commonly expected. Specifically, we predict the feasible experimental synthesis of polyvalent [RaL-n] (n = 4, 6) compounds.

Colloidal Synthesis of Cu3N Nanorods and Construction of Cu3N-Cu2O Heteronanostructures via Epitaxial Growth.

The synthesis of transition metal nitrides nanocrystals (TMNs NCs) has posed a significant challenge due to the limited reactivity of nitrogen sources at lower temperatures and the scarcity of available synthesis methods. In this study, we present a novel colloidal synthesis strategy for the fabrication of Cu3N nanorods (NRs). It is found that the trace oxygen (O2) plays an important role in the synthesis process. And a new mechanism for the formation of Cu3N is proposed. Subsequently, by employing secondary lateral epitaxial growth, the Cu3N-Cu2O heteronanostructures (HNs) can be prepared. The Cu3N NRs and Cu3N-Cu2O HNs were evaluated as precursor electrocatalysts for the CO2 reduction reaction (CO2RR). The Cu3N-Cu2O HNs demonstrate remarkable selectivity and stability with ethylene (C2H4) Faradaic efficiency (FE) up to 55.3%, surpassing that of Cu3N NRs. This study provides innovative insights into the reaction mechanism of colloidal synthesis of TMNs NCs and presents alternative options for designing cost-effective electrocatalysts to achieve carbon neutrality.

Kirkendall Effect-Driven Reversible Chemical Transformation for Reconfigurable Nanocrystals.

The potential universality of chemical transformation principles makes it a powerful tool for nanocrystal (NC) synthesis. An example is the nanoscale Kirkendall effect, which serves as a guideline for the construction of hollow structures with different properties compared to their solid counterparts. However, even this general process is still limited in material scope, structural complexity, and, in particular, transformations beyond the conventional solid-to-hollow process. We demonstrate in this work an extension of the Kirkendall effect that drives reversible structural and phase transformations between metastable metal chalcogenides (MCs) and metal phosphides (MPs). Starting from Ni3S4/Cu1.94S NCs as the initial frameworks, ligand-regulated sequential extractions and diffusion of host/guest (S2-/P3-) anions between Ni3S4/Cu1.94S and Ni2P/Cu3P phases enable solid-to-hollow-to-solid structural motif evolution while retaining the overall morphology of the NC. An in-depth mechanistic study reveals that the transformation between metastable MCs and MPs occurs through a combination of ligand-dependent kinetic control and anion mixing-induced thermodynamic control. This strategy provides a robust platform for creating a library of reconfigurable NCs with tunable compositions, structures, and interfaces.

Highly Stable 72-Nuclearity Nanocages for Efficient Synthesis of Aryl Nitriles via Ni/Cu Synergistic Catalysis.

Seeking noble-metal-free catalysts for efficient synthesis of aryl nitriles under mild conditions poses a significant challenge due to the use of hypertoxic cyanides or high-pressure/temperature NH3/O2 in conventional synthesis processes. Herein, we developed a novel framework 1 assembled by [Ni72] nanocages with excellent solvents/pH stability. To investigate the structure-activity relationship of catalytic performance, several isostructural MOFs with different molar ratios of Ni/Cu by doping Cu2+ into framework 1 (Ni0.59Cu0.41 (2), Ni0.81Cu0.19 (3), Ni0.88Cu0.12 (4), and Ni0.92Cu0.08 (5)) were prepared. Catalytic studies revealed that catalyst 3 exhibited remarkable performance in the synthesis of aryl nitriles, utilizing a formamide alternative to hypertoxic NaCN/KCN. Notably, catalyst 3 achieved an excellent TOF value of 9.8 h-1. Furthermore, catalyst 3 demonstrated its applicability in a gram-scale experiment and maintained its catalytic performance even after six recycling cycles, owing to its high stability resulting from significant electrostatic and orbital interactions between the Ni center and ligands as well as a large SOMO-LUMO energy gap supported by DFT calculations. Control experiments and DFT calculations further revealed that the excellent catalytic performance of catalyst 3 originated from the synergistic effect of Ni/Cu. Importantly, this work not only provides a highly feasible method to construct highly stable MOFs containing multinuclear nanocages with exceptional catalytic performance but also represents the first example of a heterogeneous catalyst for the synthesis of aryl nitriles using formamide as the cyanide source.

High Contrast Bioimaging of Tumor and Inflammation with a Bicyclic Dioxetane Chemiluminescent Probe.

The link between inflammation and the evolution of cancer is well established. Visualizing and tracking both tumor proliferation and the associated inflammatory response within a living organism are vital for dissecting the nexus between these two processes and for crafting precise treatment modalities. We report the creation and synthesis of an advanced NIR chemiluminescence probe that stands out for its exceptional selectivity, extraordinary sensitivity at nanomolar concentrations, swift detection capabilities, and broad application prospects. Crucially, this probe has been successfully utilized to image endogenous ONOO- across different inflammation models, including abdominal inflammation triggered by LPS, subcutaneous inflammatory conditions, and tumors grafted onto mice. These findings highlight the significant promise of chemiluminescence imaging in enhancing our grasp of the intricate interplay between cancer and inflammation and in steering the development of potent, targeted therapeutic strategies.

Understanding the Electronic Structure and Chemical Bonding in the 2D Fullerene Monolayer.

Recently synthesized two-dimensional (2D) monolayer quasi-hexagonal-phase fullerene (qHPC60) demonstrates excellent thermodynamic stability. Within this monolayer, each fullerene cluster is surrounded by six adjacent C60 cages along an equatorial plane and is connected by both C-C single bonds and [2 + 2] cycloaddition bonds that serve as bridges. In this study, we investigate the stability mechanism of the 2D qHPC60 monolayer by examining the electronic structure and chemical bonding through state-of-the-art theoretical methodologies. Density functional theory (DFT) studies reveal that 2D qHPC60 possesses a moderate direct electronic band gap of 1.46 eV, close to the experimental value (1.6 eV). It is found that the intermolecular bridge bonds play a crucial role in enhancing the charge flow and redistribution among C60 cages, leading to the formation of dual π-aromaticity within the C60 sphere and stabilizing the 2D framework structure. Furthermore, we identify a series of delocalized superatom molecular orbitals (SAMOs) within the 2D qHPC60 monolayer, exhibiting atomic orbital-like behavior and hybridization to form nearly free-electron (NFE) bands with σ/π bonding and σ*/π* antibonding properties. Our findings provide insights into the design and potential applications of NFE bands derived from SAMOs in 2D qHPC60 monolayers.

Complexation of Hexavalent Neptunium(VI) with Oxydiacetic Acid and Its Amide Derivatives in Aqueous Solution: Spectrophotometry and DFT Calculations.

Unfolding the solution coordination chemistry of high-valent transuranium elements with the "CHON"-type ligands is important to understand the fundamental chemistry of actinides and to design more efficient extractants for partitioning of transuranium elements in advanced nuclear fuel cycles. Here, the complexation of a hexavalent neptunyl ion (NpO22+ or Np(VI)) with oxydiacetic acid (ODA) has been systematically investigated in comparison with its amide analogues N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) and N,N,N',N'-tetramethyl-3-oxa-glutaramide (TMOGA) both experimentally and computationally. The formation of both 1:1 and 1:2 complexes between Np(VI) and the three ligands was identified by spectrophotometry, and their stability constants were obtained and compared with those of hexavalent U(VI) and Pu(VI). The corresponding bonding nature is elucidated by using energy decomposition analysis (EDA), electrostatic potential (ESP), ELF contours, and natural orbitals for chemical valence (NOCV) methods, which shows that the Np-O bonds are essentially ionic in character and the unoccupied 6d orbitals of Np play a key role in enhancing the covalent interactions between Np(VI) and the three ligands.

Theoretical Design of Thorium Nitride MXenes.

Actinides with 5f6d7s valence orbitals feature special physicochemical properties different from those of the other elements. Actinide-based two-dimensional (2D) materials combine the distinctive physics of actinides with the quantum size effect of 2D materials, but relevant studies are scarce. Since Th has a valence electron configuration of 6d27s2 like Ti, and Ti-based MXenes show excellent stability and versatile applications, whether Th can form stable MXenes has become an intriguing question. Herein, we designed Th2N, Th3N2, and Th4N3 MXenes and investigated their physical properties, functionalization, and potential applications using density functional theory. Their stabilities are validated by global minimum search, phonon spectra, ab initio molecular dynamics, enthalpy of formation, and energy above the hull. All the Th-N MXenes exhibit metallic properties and are stabilized by the electrostatic interaction between Th and N ions, as well as the covalent bonding interaction between the Th 6d/5f and N 2p/2s orbitals. The H-, O-, and F-functionalization3N2 MXene improve its stability while preserving its metallicity, and the O-functionalized Th3N2 MXene shows promising catalytic activity for hydrogen evolution. The thorium nitride MXenes enrich the family of actinide-based 2D materials and extend our understanding of the structures and properties induced by actinide elements in low-dimensional materials.

Structures of Th4+ aqueous solutions: insights from AIMD and metadynamics simulations.

Solution chemistry of actinide ions is critical to understanding the solvation behaviors and hydrolysis process. Using tetravalent thorium ion Th4+ as a representative example, we investigate the local structures and dynamic behaviors of hydrated Th4+ ions by ab initio molecular dynamics (AIMD) simulations using the recently developed norm-conserving pseudopotentials and basis sets optimized for actinides (J.-B. Lu et al., J. Chem. Theory Comput. 2021, 17, 3360-3371). AIMD simulations reveal two distinct solvation shells, with the first shell comprising 9 water molecules at approximately rTh-O = 2.50 Å and exhibiting a tricapped trigonal prism geometry. These conclusions are confirmed through metadynamics simulations and further structural analysis. AIMD simulations also show the slight effect of temperature and counterions on the structure of the solution. The structured solvation shells of the highly charged Th4+ ion with the specific geometry, distinct from the structure of liquid water, lead to corresponding structural changes in the hydrogen bond network in water. Additionally, beyond the solvent-shared ion pair (SIP) state observed in the unbiased AIMD simulations, the metadynamics simulations reconstruct a two-dimensional free energy surface that clearly indicates the potential stability of the contact ion pair (CIP) state in the system with Cl- as a counterion. The findings in this work provide insights into the solution chemistry of actinides and serve as a reference for studying other actinide solution systems.

Variational quantum imaginary time evolution for matrix product state Ansatz with tests on transcorrelated Hamiltonians.

The matrix product state (MPS) Ansatz offers a promising approach for finding the ground state of molecular Hamiltonians and solving quantum chemistry problems. Building on this concept, the proposed technique of quantum circuit MPS (QCMPS) enables the simulation of chemical systems using a relatively small number of qubits. In this study, we enhance the optimization performance of the QCMPS Ansatz by employing the variational quantum imaginary time evolution (VarQITE) approach. Guided by McLachlan's variational principle, the VarQITE method provides analytical metrics and gradients, resulting in improved convergence efficiency and robustness of the QCMPS. We validate these improvements numerically through simulations of H2, H4, and LiH molecules. In addition, given that VarQITE is applicable to non-Hermitian Hamiltonians, we evaluate its effectiveness in preparing the ground state of transcorrelated Hamiltonians. This approach yields energy estimates comparable to the complete basis set (CBS) limit while using even fewer qubits. In particular, we perform simulations of the beryllium atom and LiH molecule using only three qubits, maintaining high fidelity with the CBS ground state energy of these systems. This qubit reduction is achieved through the combined advantages of both the QCMPS Ansatz and transcorrelation. Our findings demonstrate the potential practicality of this quantum chemistry algorithm on near-term quantum devices.

Improved optimization for the neural-network quantum states and tests on the chromium dimer.

The advent of Neural-network Quantum States (NQS) has significantly advanced wave function ansatz research, sparking a resurgence in orbital space variational Monte Carlo (VMC) exploration. This work introduces three algorithmic enhancements to reduce computational demands of VMC optimization using NQS: an adaptive learning rate algorithm, constrained optimization, and block optimization. We evaluate the refined algorithm on complex multireference bond stretches of H2O and N2 within the cc-pVDZ basis set and calculate the ground-state energy of the strongly correlated chromium dimer (Cr2) in the Ahlrichs SV basis set. Our results achieve superior accuracy compared to coupled cluster theory at a relatively modest CPU cost. This work demonstrates how to enhance optimization efficiency and robustness using these strategies, opening a new path to optimize large-scale restricted Boltzmann machine-based NQS more effectively and marking a substantial advancement in NQS's practical quantum chemistry applications.

Correction: Effectiveness of an Artificial Intelligence-Assisted App for Improving Eating Behaviors: Mixed Methods Evaluation.

[This corrects the article DOI: 10.2196/46036.].

Effectiveness of an Artificial Intelligence-Assisted App for Improving Eating Behaviors: Mixed Methods Evaluation.

BACKGROUND: A plethora of weight management apps are available, but many individuals, especially those living with overweight and obesity, still struggle to achieve adequate weight loss. An emerging area in weight management is the support for one's self-regulation over momentary eating impulses. OBJECTIVE: This study aims to examine the feasibility and effectiveness of a novel artificial intelligence-assisted weight management app in improving eating behaviors in a Southeast Asian cohort. METHODS: A single-group pretest-posttest study was conducted. Participants completed the 1-week run-in period of a 12-week app-based weight management program called the Eating Trigger-Response Inhibition Program (eTRIP). This self-monitoring system was built upon 3 main components, namely, (1) chatbot-based check-ins on eating lapse triggers, (2) food-based computer vision image recognition (system built based on local food items), and (3) automated time-based nudges and meal stopwatch. At every mealtime, participants were prompted to take a picture of their food items, which were identified by a computer vision image recognition technology, thereby triggering a set of chatbot-initiated questions on eating triggers such as who the users were eating with. Paired 2-sided t tests were used to compare the differences in the psychobehavioral constructs before and after the 7-day program, including overeating habits, snacking habits, consideration of future consequences, self-regulation of eating behaviors, anxiety, depression, and physical activity. Qualitative feedback were analyzed by content analysis according to 4 steps, namely, decontextualization, recontextualization, categorization, and compilation. RESULTS: The mean age, self-reported BMI, and waist circumference of the participants were 31.25 (SD 9.98) years, 28.86 (SD 7.02) kg/m2, and 92.60 (SD 18.24) cm, respectively. There were significant improvements in all the 7 psychobehavioral constructs, except for anxiety. After adjusting for multiple comparisons, statistically significant improvements were found for overeating habits (mean -0.32, SD 1.16; P<.001), snacking habits (mean -0.22, SD 1.12; P<.002), self-regulation of eating behavior (mean 0.08, SD 0.49; P=.007), depression (mean -0.12, SD 0.74; P=.007), and physical activity (mean 1288.60, SD 3055.20 metabolic equivalent task-min/day; P<.001). Forty-one participants reported skipping at least 1 meal (ie, breakfast, lunch, or dinner), summing to 578 (67.1%) of the 862 meals skipped. Of the 230 participants, 80 (34.8%) provided textual feedback that indicated satisfactory user experience with eTRIP. Four themes emerged, namely, (1) becoming more mindful of self-monitoring, (2) personalized reminders with prompts and chatbot, (3) food logging with image recognition, and (4) engaging with a simple, easy, and appealing user interface. The attrition rate was 8.4% (21/251). CONCLUSIONS: eTRIP is a feasible and effective weight management program to be tested in a larger population for its effectiveness and sustainability as a personalized weight management program for people with overweight and obesity. TRIAL REGISTRATION: ClinicalTrials.gov NCT04833803; https://classic.clinicaltrials.gov/ct2/show/NCT04833803.

Mn-Incorporation-Induced Phase Transition in Bottom-Up Synthesized Colloidal Sub-1-nm Ni(OH)2 Nanosheets for Enhanced Oxygen Evolution Catalysis.

Sub-1-nm structures are attractive for diverse applications owing to their unique properties compared to those of conventional nanomaterials. Transition-metal hydroxides are promising catalysts for oxygen evolution reaction (OER), yet there remains difficulty in directly fabricating these materials within the sub-1-nm regime, and the realization of their composition and phase tuning is even more challenging. Here we define a binary-soft-template-mediated colloidal synthesis of phase-selective Ni(OH)2 ultrathin nanosheets (UNSs) with 0.9 nm thickness induced by Mn incorporation. The synergistic interplay between binary components of the soft template is crucial to their formation. The unsaturated coordination environment and favorable electronic structures of these UNSs, together with in situ phase transition and active site evolution confined by the ultrathin framework, enable efficient and robust OER electrocatalysis. They exhibit a low overpotential of 309 mV at 100 mA cm-2 as well as remarkable long-term stability, representing one of the most high-performance noble-metal-free catalysts.

Region-Controlled Framework Interface Mediated Anion Exchange Chemical Transformation to Designed Metal Phosphosulfide Heteronanostructures.

Postsynthetic chemical transformation provides a powerful platform for creating heteronanostructures (HNs) with well-defined materials and interfaces that generate synergy or enhancement. However, it remains a synthetic bottleneck for the precise construction of HNs with increased degrees of complexity and more elaborate functions in a predictable manner. Herein, we define a general transformative protocol for metal phosphosulfide HNs based on tunable hexagonal Cu1.81S frameworks with corner-, edge- and face-controlled growth of Co2P domains. The region-controlled Cu1.81S-Co2P framework interfaces can serve as "kinetic barriers" in mediating the direction and rate between P and S anion exchange reactions, thus leading to a family of morphology and phase designed Cu3P1-xSx-Co2P HNs with hollow (branched, dotted and crown), porous and core-shell architectures. This study reveals the internal transformation mechanism between metal sulfide and phosphide nanocrystals, and opens up a new way for the rational synthesis of metastable HNs that are otherwise inaccessible.

Nursing students' readiness towards the 'new normal' in clinical practice: a distributed cognition qualitative perspective.

BACKGROUND: Clinical practicums are a core component of baccalaureate nursing education. Following the coronavirus pandemic, there have been extensive changes in the workforce environment that may potentially affect nursing students' experience and readiness for clinical practicums. METHODS: A qualitative study was conducted to explore final-year nursing students' experiences and readiness for their final clinical practicum before becoming a registered nurse. A purposive sample of 24 final-year baccalaureate nursing students was included in this study. Individual semi-structured interviews were conducted face-to-face via Zoom. The data was analysed using an inductive thematic analysis approach. RESULTS: Three themes depicting students' experiences and clinical readiness were elucidated. The themes included: (1) Experiencing multiple concerns, (2) requiring a network of support, and (3) easing the transition to professional practice. Students considered the final clinical practicum as challenging and demanding which evoked numerous concerns. CONCLUSIONS: Considering the stress that final-year nursing students experience, it will be important to devise strategies ranging from personal, relational, and environmental protective factors to enable their successful transition and completion of clinical practice.

Molybdenum Disulfide Induced Phase Control Synthesis of Multi-dimensional Co3S4-MoS2 Heteronanostructures via Cation Exchange.

Phase control over cation exchange (CE) reactions has emerged as an important approach for the synthesis of nanomaterials (NMs), enabling precise determination of their reactivity and properties. Although factors such as crystal structure and morphology have been studied for the phase engineering of CE reactions in NMs, there remains a lack of systematic investigation to reveal the impact for the factors in heterogeneous materials. Herein, we report a molybdenum disulfide induced phase control method for synthesizing multidimensional Co3S4-MoS2 heteronanostructures (HNs) via cation exchange. MoS2 in parent Cu1.94S-MoS2 HNs are proved to affect the thermodynamics and kinetics of CE reactions, and facilitate the formation of Co3S4-MoS2 HNs with controlled phase. This MoS2 induced phase control method can be extended to other parent HNs with multiple dimensions, which shows its diversity. Further, theoretical calculations demonstrate that Co3S4 (111)/MoS2 (001) exhibits a higher adhesion work, providing further evidence that MoS2 enables phase control in the HNs CE reactions, inducing the generation of novel Co3S4-MoS2 HNs. As a proof-of-concept application for crystal phase- and dimensionality-dependent of cobalt sulfide based HNs, the obtained Co3S4-MoS2 heteronanoplates (HNPls) show remarkable performance in hydrogen evolution reactions (HER) under alkaline media. This synthetic methodology provides a unique design strategy to control the crystal structure and fills the gap in the study of heterogeneous materials on CE reaction over phase engineering that are otherwise inaccessible.

Synthesis and Characterization of U≡C Triple Bonds in Fullerene Compounds.

Despite decades of efforts, the actinide-carbon triple bond has remained an elusive target, defying synthesis in any isolable compound. Herein, we report the successful synthesis of uranium-carbon triple bonds in carbide-bridged bimetallic [U≡C-Ce] units encapsulated inside the fullerene cages of C72 and C78. The molecular structures of UCCe@C2n and the nature of the U≡C triple bond were characterized through X-ray crystallography and various spectroscopic analyses, revealing very short uranium-carbon bonds of 1.921(6) and 1.930(6) Å, with the metals existing in their highest oxidation states of +6 and +4 for uranium and cerium, respectively. Quantum-chemical studies further demonstrate that the C2n cages are crucial for stabilizing the [UVI≡C-CeIV] units through covalent and coordinative interactions. This work offers a new fundamental understanding of the elusive uranium-carbon triple bond and informs the design of complexes with similar bonding motifs, opening up new possibilities for creating distinctive molecular compounds and materials.

On the highest oxidation states of the actinoids in AnO4 molecules (An = Ac - Cm): A DMRG-CASSCF study.

Actinoid tetroxide molecules AnO4 (An = Ac - Cm) are investigated with the ab initio density matrix renormalization group (DMRG) approach. Natural orbital shapes are used to read out the oxidation state (OS) of the f-elements, and the atomic orbital energies and radii are used to explain the trends. The highest OSs reveal a "volcano"-type variation: For An = Ac - Np, the OSs are equal to the number of available valence electrons, that is, AcIII , ThIV , PaV , UVI , and NpVII . Starting with plutonium as the turning point, the highest OSs in the most stable AnO4 isomers then decrease as PuV , AmV , and CmIII , indicating that the 5f-electrons are hard to be fully oxidized off from Pu onward. The variations are related to the actinoid contraction and to the 5f-covalency characteristics. Combined with previous work on OSs, we review their general trends throughout the periodic table, providing fundamental understanding of OS-relevant phenomena.