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MAX phases and its derived two-dimensional MXenes have attracted considerable interest because of their rich structural chemistry and multifunctional applications. Lewis acid molten salt route provides an opportunity for structure design and performance manipulation of new MAX phases and MXenes, Although a series of new MAX phases and MXenes were successfully prepared via Lewis acid melt route in recent years, few work is explored on nitride MAX phases and MXenes. Herein, a new copper-based 413-type Ti4CuN3 MAX phase was synthesized through isomorphous replacement reaction using Ti4AlN3 MAX phase precursor in molten CuCl2. In addition, it was found that at high temperature Ti4N3Clx MXene will transform into two-dimensional cubic TiNα nanosheets with improved structural stability.

Two-dimensional layered transition metal carbides (MXenes), have huge potential advantage for applications in hydrogen evolution reaction (HER). However, the hindered hydrogen evolution at large current densities and the instability of MXenes during HER remains major challenges. Herein, we report the MoS2/Mo2CTx nanoarray with aerophobic structure via molten salt synthesis. In situ vertical distribution of MoS2 nanoarray on the surface of Mo2CTx accelerates hydrogen gas release from the electrode, exhibiting significantly enhanced catalytic activity and stability to bare MoS2 and Mo2CTx. The MoS2/Mo2CTx nanoarray possesses excellent stability at −100 mA/cm2 for 100 h with only 3% overpotential increase. Our work provides guidance for developing high-stability MXene-based catalysts by virtue of in situ bonding between nanoarray and MXene.

Reversal of cancer drug resistance remains a critical challenge in chemotherapy. Mitochondria-targeted drug delivery has been suggested to mitigate drug resistance in cancer. To overcome the intrinsic limitations in conventional mitochondrial targeting strategies, we develop mitochondrial temperature-responsive drug delivery to reverse doxorubicin (DOX) resistance in lung cancer. Results demonstrate that the thermoresponsive nanocarrier can prevent DOX efflux and facilitate DOX accumulation and mitochondrial targeting in DOX-resistant tumors. As a consequence, thermoresponsive nanocarrier enhances the cytotoxicity of DOX and reverses the drug resistance in tumor-bearing mice. This work represents the first example of mitochondrial temperature-responsive drug delivery for reversing cancer drug resistance.

Abstract Electromagnetic (EM) wave pollution is harmful to human health and environment, thus it is absolutely important to develop new electromagnetic wave absorbing materials. MAX phases have been attracted more attention as a potential candidate for electromagnetic wave absorbing materials due to their high conductivity and nanolaminated structure. Herein, two new magnetic MAX phases with multiprincipal elements ((Ti1/3Nb1/3Ta1/3)2FeC and (Ti0.2V0.2Nb0.2Ta0.2Zr0.2)2FeC) in which Fe atoms replace Al atoms in the A sites are successfully synthesized by an isomorphous replacement reaction of multiprincipal (Ti1/3Nb1/3Ta1/3)2AlC and (Ti0.2V0.2Nb0.2Ta0.2Zr0.2)2AlC MAX phases with Lewis acid salt (FeCl2). (Ti1/3Nb1/3Ta1/3)2FeC and (Ti0.2V0.2Nb0.2Ta0.2Zr0.2)2FeC exhibit ferromagnetic behavior, and the Curie temperature (Tc) are 302 and 235 K, respectively. The dual electromagnetic absorption mechanisms that include dielectric and magnetic loss, which is realized in these multiprincipal MAX phases. The minimum reflection loss (RL) of (Ti1/3Nb1/3Ta1/3)2FeC is −44.4 dB at 6.56 GHz with 3 mm thickness, and the effective bandwidth is 2.48 GHz. Additionally, the electromagnetic wave absorption properties of the magnetic MAX phases indicate that magnetic loss also plays an important role besides dielectric loss. This work shows a promising composition‐design strategy to develop MAX phases with good EM wave absorption performance via simultaneously regulating dielectric and magnetic loss together.

Entropy stabilization is an effective method to design and explore MAX phases with outstanding properties via tuning constituent elements and crystal structures, which have received considerable critical attention. Currently, some medium‐/high‐entropy (ME/HE) MAX phases, whose A layers are composed of Al, S, and magnetic elements, are reported, while few discussions about ME/HE‐MAX phases with other A elements (e.g., Sn) are conducted. Herein, fully dense ME/HE‐MAX phase bulks ((TiVNb)2SnC, (TiVNbZr)2SnC, and (TiVNbZrHf)2SnC) are designed and synthesized because of the chemical diversity of MAX phases. The results of Rietveld refinement of X‐ray diffraction, scanning electron microscopy, and high‐resolution scanning transmission electron microscopy‐affiliated energy‐dispersive spectrometer analysis comprehensively verify the crystal structure of ME/HE‐MAX phases. Both the electrical conductivity and the charge carrier mobility are significantly lower than the reported correlation ternary MAX phases, due to the electron scattering and structural defects in ME/HE‐MAX phase crystal structures. Similarly, the electron contribution of thermal conductivity is gradually declining; on the contrary, the phonon plays an increasingly dominant role as temperature increases. Owing to the richness in composition of MAX phases, herein, a composition design route for discovering new MAX phases and tuning their properties is indicated.

As one of the accident-tolerance nuclear fuels with potential application prospects, U3Si2 shows its merits of high melting point, high thermal conductivity and high uranium density. However, the mechanical brittleness is one major problem for its practical applications. The strategy of Al-alloying could effectively improve the ductility of U3Si2, yet the intrinsic mechanism is not clear. In this work, the mechanisms for the ductility enhancement of U3Si2 via substituting Al into Si site (i.e. U3Si1.75Al0.25) is studied from two aspects: 1) the interatomic bonding characteristics that are responsible for the ductility enhancement are analyzed in detail; 2) the tensile-shear tests of U3Si1.75Al0.25 are carried out via first-principle calculations, and then the ductility-enhancing mechanism is analyzed. It is found that the increasing number of bonding electrons in U–U layer results in the enhancement of the d-σ interactions between U–Si and U–Si–Al six-membered rings, while the decreasing number of bonding electrons within U–Si layer corresponds to the weakening of the d-s interactions. Finally, one electronic structure model is proposed to picture the interactions of bonding electrons during the tensile-shear tests; providing a novel and inspiration logic of mechanical property modification for alloying-U3Si2.

Radiation-induced esophageal injury remains a limitation for the process of radiotherapy for lung and esophageal cancer patients. Esophageal epithelial cells are extremely sensitive to irradiation, nevertheless, factors involved in the radiosensitivity of esophageal epithelial cells are still unknown. Terminal uridyl transferase 4 (TUT4) could modify the sequence of miRNAs, which affect their regulation on miRNA targets and function. In this study, we used transcriptome sequencing technology to identify mRNAs that were differentially expressed before and after radiotherapy in esophageal epithelial cells. We further explored the mRNA expression profiles between wild-type and TUT4 knockout esophageal epithelial cells. Volcano and heatmap plots unsupervised hierarchical clustering analysis were performed to classify the samples. Enrichment analysis on Gene Ontology functional annotations and Kyoto Encyclopedia of Genes and Genomes pathways was performed. We annotated differential genes from metabolism, genetic information processing, environmental information processing, cellular processes, and organismal systems human diseases. The aberrantly expressed genes are significantly enriched in irradiation-related biological processes, such as DNA replication, ferroptosis, and cell cycle. Moreover, we explored the distribution of transcription factor family and its target genes in differential genes. These mRNAs might serve as therapeutic targets in TUT4-related radiation-induced esophageal injury.

Abstract MAX phases are gaining attention as precursors of two-dimensional MXenes that are intensively pursued in applications for electrochemical energy storage. Here, we report the preparation of V2SnC MAX phase by the molten salt method. V2SnC is investigated as a lithium storage anode, showing a high gravimetric capacity of 490 mAh g−1 and volumetric capacity of 570 mAh cm−3 as well as superior rate performance of 95 mAh g−1 (110 mAh cm−3) at 50 C, surpassing the ever-reported performance of MAX phase anodes. Supported by operando X-ray diffraction and density functional theory, a charge storage mechanism with dual redox reaction is proposed with a Sn–Li (de)alloying reaction that occurs at the edge sites of V2SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V2C layers with Li. This study offers promise of using MAX phases with M-site and A-site elements that are redox active as high-rate lithium storage materials.

Objective: A series of experiments were carried out to study the comparative decorporation efficacy and toxicity of three tetradentate hydroxypyridinone ligands (3LI-1-Cm-3,2-HOPO, 5LIO-1-Cm-3,2-HOPO, and 7LIO-1-Cm-3,2-HOPO) with the variation of the linker length and the substituents. Methods: Three ligands were obtained from a 4-step synthesis via the amidation of HOPO unit and different backbones. Potentiometric titrations were carried out to evaluate the formation constants of their corresponding uranyl complexes. CCK-8 and colony formation assays were used to compare the cytotoxicity of the three ligands and uranyl using renal proximal tubular epithelial (NRK-52E) cells. In vitro uranium removal assays were performed to assess decorporation efficiencies of those ligands by co-incubating uranium and chelators with NRK-52E cells for 48 h. Results: Among the three ligands, 5LIO-1-Cm-3,2-HOPO exhibits the highest uranyl affinity (logβ110 ​= ​18.6(7)) in comparison to the other two ligands (logβ110 ​= ​14.9(2) for 3LI-1-Cm-3,2-HOPO and logβ110 ​= ​16.7(1) for 7LIO-1-Cm-3,2-HOPO). The results of CCK-8 tests and colony formation assays further elucidate that 5LIO-1-Cm-3,2-HOPO and 7LIO-1-Cm-3,2-HOPO both show a similar level of cytotoxicity compared with ZnNa3-DTPA at relatively low ligand concentrations. In contrast, in the 3LI-1-Cm-3,2-HOPO treated group, the cell viability decreased markedly with the increase of the ligand concentrations, and the colony formation capability of NRK-52E cells was inhibited. Furthermore, the comparative decorporation efficacy of the three ligands was obtained from in vitro uranium removal assays, suggesting that these ligands could significantly inhibit the cellular uptake and prompt the cellular release of uranium from NRK-52E cells by the level of 81.9%, 91.8%, and 87.1%, respectively. Conclusion: Our current results demonstrate that the linker/backbone species would significantly affect the decorporation efficacy and toxicity of the tetradentate 3-hydroxy-2-pyridinone ligands, which is informative for the future design and modification of novel decorporation ligands.

Separation of 99TcO4 − from nuclear waste at the Savannah River Site is hampered by the extreme conditions. Here, the authors propose a solution by developing an alkaline-resistant metal organic framework material featuring unique recognition sites for selective incorporation of 99TcO4 − anions.

It is unclear whether 2D metal dichalcogenides (TMD) alone can cause ferroptotic cell death. Here, the authors show TMD nanosheets induced ferroptosis in mammalian cell lines and in a mouse model after aspiration of TMD materials into lungs, causing ferroptotic cell death.

Abstract Background To effectively applied nanomaterials (NMs) in medicine, one of the top priorities is to address a better understanding of the possible sub-organ transfer, clearance routes, and potential toxicity of the NMs in the liver and kidney. Results Here we explored how the surface chemistry of polyethylene glycol (PEG), chitosan (CS), and polyethylenimine (PEI) capped gold nanoparticles (GNPs) governs their sub-organ biodistribution, transfer, and clearance profiles in the liver and kidney after intravenous injection in mice. The PEG-GNPs maintained dispersion properties in vivo, facilitating passage through the liver sinusoidal endothelium and Disse space, and were captured by hepatocytes and eliminated via the hepatobiliary route. While, the agglomeration/aggregation of CS-GNPs and PEI-GNPs in hepatic Kupffer and endothelial cells led to their long-term accumulation, impeding their elimination. The gene microarray analysis shows that the accumulation of CS-GNPs and PEI-GNPs in the liver induced obvious down-regulation of Cyp4a or Cyp2b related genes, suggesting CS-GNP and PEI-GNP treatment impacted metabolic processes, while the PEI-GNP treatment is related with immune responses. Conclusions This study demonstrates that manipulation of nanoparticle surface chemistry can help NPs selectively access distinct cell types and elimination pathways, which help to clinical potential of non-biodegradable NPs.

New MAX phases Ti2(AlxCu1−x)N and Nb2CuC were synthesized by A-site replacement by reacting Ti2AlN and Nb2AlC, respectively, with CuCl2 or CuI molten salt. X-ray diffraction, scanning electron microscopy, and atomically resolved scanning transmission electron microscopy showed complete A-site replacement in Nb2AlC, which lead to the formation of Nb2CuC. However, the replacement of Al in Ti2AlN phase was only close to complete at Ti2(Al0.1Cu0.9)N. Density-functional theory calculations corroborated the structural stability of Nb2CuC and Ti2CuN phases. Moreover, the calculated cleavage energy in these Cu-containing MAX phases are weaker than in their Al-containing counterparts.

In vivo decorporation of U(VI) from bones is an unsolved challenge because of the formation of stable uranium phosphate complexes. Here, the authors develop a hydroxypyridonone-based ligand with strong uranium complexation and low cytotoxicity. They find this ligand effectively removes uranium from kidney and bones in mice, and is suitable for oral administration.

The therapeutic efficiency of ascorbate is limited by its slow autoxidation. Here, the authors show the application of concave-structured palladium nanocrystals for the treatment of colorectal cancer through the oxidation of ascorbate, enhancing the production of oxidative stresses specifically on cancer cells.

Direct removal of 99TcO4 − from highly radioactive and acidic nuclear waste solutions is beneficial for uranium and plutonium recovery and radioactive pollution control but this represents a huge challenge. Here the authors show a cationic polymeric network with high 99TcO4 − sorption capability and stability.

Noble metal nanoparticles are potential antibacterial agents, perhaps owing to their enzyme-like activities. Here, the authors find that the exposed facets of palladium nanocrystals demonstrate their specific antibacterial behavior against both Gram-positive and Gram-negative bacteria.

Cationic metal-organic frameworks provide promising opportunities to capture anionic pollutants, but stable frameworks with sufficiently large pores are lacking. Here the authors present a thorium-based mesoporous, cationic and hydrolytically-stable MOF that can rapidly trap inorganic and organic anionic pollutants.

Zirconium phosphonate based metal-organic frameworks often exhibit superior chemical stabilities, but typically exist as poorly crystalline or amorphous materials. Here the authors exploit an ionothermal method to obtain highly porous and remarkably stable single crystalline zirconium phosphonate frameworks that can efficiently remove uranyl ions from aqueous solutions.

Abstract Super‐small nanoclusters may intrinsically trigger specific molecular pathway for disease treatment in vitro/vivo. To prove the hypothesis the super‐small nanoclusters, e.g., Au clusters, are directly used to treat rheumatoid arthritis (RA) in vitro/vivo. RA is a chronic autoimmune disease that is characterized by the inflammation of joints and the unreversible destruction of the cartilage/bone. Au clusters significantly suppress lipopolysaccharide (LPS)‐induced proinflammatory mediator production in the murine macrophage cell line by inhibiting the signaling pathways that regulate the major proinflammatory mediator genes. In preclinical rat RA studies, Au clusters strongly prevent type II collagen‐induced rat RA without systemic side effects. Compared with the clinical first‐line anchored anti‐RA drug, methotrexate, Au clusters equally inhibit inflammation in vivo. Type II collagen‐induced rat RA is characterized with the destruction of cartilage/bone; treatment with Au clusters reverses the destruction of cartilage/bone to its normal state. This is because Au clusters directly inhibit receptor activator of nuclear factor‐κB ligand (RANKL)‐induced osteoclast differentiation and function through the downregulation of osteoclast‐specific genetic marker expression. However the methotrexate almost has no positive effect for this key issue in rat RA therapy. These data prove that the super‐small nanoclusters, e.g., Au clusters, could be a novel candidate nanodrug for RA treatment.

Trivalent lanthanides possess similar chemical properties, making their separation from one another challenging. Here, Wang and colleagues demonstrate that their subtle chemical differences can be greatly amplified during borate crystallization, leading to a low cost and highly efficient separation strategy.

The adsorption of uranyl on hydroxylated α-SiO2(001) in the presence of a series of anionic ligands, i.e. OHâ, CO32-, NO3-, H2PO4-, HPO42-, CH3COOâ (Acâ), C6H5COOâ (PhCO2-), C6H5Oâ (PhOâ), was studied by the periodic density functional theory (DFT) implemented in the Vienna ab initio simulation package (VASP). For the ligands other than OHâ and PhOâ, only the bidentate coordination modes to the uranyl were considered. The excess charge effect of a charged system was first evaluated by constructing models with net charge as is or neutralized by creating defect at the bottom of silica, and the results show that a neutralized model, even with defects, is more realistic than the charged ones. All uranyl species prefer to bind with the deprotonated site (î¸Oâ) rather than the protonated one (î¸OH), which suggests that the increase of pH, which leads to the deprotonation of the surface, may enhance the uranyl adsorption. On the other hand, the anionic ligands, which are formed at higher pH, have negative effects. The weaker acidic ligands, such as H2CO3, H3PO4 and H2O, whose speciation in solutions is sensitive to the fluctuation of pH, have more complex effect on the uranyl adsorption than strong acids or bases. Humic substances may coordinate with uranyl through carboxyl and phenolic groups, with the carboxyl group bound stronger. The ternary complexes with one bidentate (or monodentate) anion and one (or two) H2O as ligands, which leads to the uranyl penta-coordinated in its equatorial plane, are more favorable than other configurations when bound to the same anionic ligand. Both the charged nature and the coordination behavior of an anionic ligand are relevant to its ability to influence the adsorption of uranyl on the mineral surface. In addition, the uranyl species adsorbed at the surface functionalized by anionic ligands were also addressed, and the functionalized surfaces have weaker interaction with hydrated uranyl dication. Keywords: Density functional theory, Adsorption, α-SiO2(001), Uranyl, Anionic ligands

In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides was determined with an atomic force microscope to be 0.452 nm. The approach is compatible with other surface patterning technologies, such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits.

A macroporous silica-based 4,4′,(5′)-di(t-butylcyclohexano)-18-crown-6 (DtBuCH18C6)-impregnated polymeric composite, (DtBuCH18C6 + Oct)/SiO 2 -P, was synthesized by molecular modification of DtBuCH18C6 with 1-octanol through hydrogen bonding. This was achieved by impregnating and immobilizing DtBuCH18C6 and 1-octanol molecules in the pores of macroporous SiO 2 -P particles possessing a mean pore diameter of 50 μm. The adsorption of some fission and non-fission products contained in highly active liquid waste (HLW) such as Ru(III), Mo(VI), Pd(II), Na(I), K(I), Cs(I), Sr(II), Ba(II), La(III) and Y(III) onto (DtBuCH18C6 + Oct)/SiO 2 -P was investigated at 298 K. The effects of contact time and HNO 3 concentration within the range 0.1–5.0 M were examined. Increasing the HNO 3 concentration from 0.1 M to 2.0 M led to a significant increase in the adsorption of Sr(II), followed by a decrease when the HNO 3 concentration was increased further to 5.0 M. The optimum concentration of HNO 3 in the adsorption of Sr(II) onto (DtBuCH18C6 + Oct)/SiO 2 -P was determined as 2.0 M. For the other ions examined with the exception of Ba(II), very weak or almost non-existent adsorption capacities were observed at all HNO 3 concentrations. The leaching of total organic carbon (TOC) from (DtBuCH18C6 + Oct)/SiO 2 -P into the aqueous phase was evaluated. Over the HNO 3 concentration range 0.1–3.0 M, the quantity of TOC leached was ca. 40 ppm compared with 355.8–373.3 ppm at HNO 3 concentrations above 4.0 M. Significant reduction of TOC leaching from the macroporous silica-based DtBuCH18C6-impregnated polymeric composite was achieved in 2.0 M HNO 3 . Such behaviour could be of great benefit in using (DtBuCH18C6 + Oct)/SiO 2 -P for the partitioning of Sr(II) from HLW by extraction chromatography.