Electrochemical Lithium Storage Performance of Molten Salt Derived V_(2)SnC MAX Phase

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 V_(2)SnC MAX phase by the molten salt method.V_(2)SnC 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.Sup-ported 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 V_(2)SnC particles where Sn atoms are exposed to the electrolyte followed by a redox reaction that occurs at V_(2)C 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.

镎(Ⅳ)、镅(Ⅲ)、锔(Ⅲ)的AMBER力场参数化及评估

锕系元素具有高放射性和毒性,为开展锕系水溶液化学的实验研究带来了困难与挑战。得益于理论计算方法和计算能力的快速发展,运用分子动力学模拟水溶液环境并研究锕系在水溶液当中的化学行为成为一种可替代的方法。本文拟合了Np^4+、Am^3+、Cm^3+三种金属离子的力场参数并进行了评估,进而将其用于溶液配位化学和动力学研究。为了研究的系统性,也开展了Th^4+、U^4+、Pu^4+三种锕系离子的分子模拟研究。基于对上述六种离子的分子动力学研究,系统报道了该六种锕系离子的第一、二溶剂化层结构、性质、立体化学及驻留时间等方面的共性与特性,并从能量方面探究这些内在差异的原因。结果显示,本文报道的参数适用于锕系离子的配位结构和结合自由能的研究,但对于动力学性质的研究,宜谨慎用于相同价态的锕系离子溶液体系的定性理解。本文也探究了六种锕系离子在水溶液中与Cl^-、NO_3^-和CO_3^(2-)的相互作用,分析了各配合物配位模式、成键规律及结合强弱。综上所述,本项工作发展了三种关键锕系离子的力场参数,有助于开展基于AMBER力场的动力学方法的An^3+/^4+溶液化学的研究,丰富了对An^3+/^4+的水溶液中配位化学的认识。

Hierarchical and self-supporting honeycomb LaNi_5 alloy on nickel foam for overall water splitting in alkaline media

Ni-based metallic foams possessing large specific surfaces and open cell structures are of specific interest as catalysts or catalyst carriers for electrolysis of water.Traditional fabrication of Nickel foam limits the element modification choices to several inert transition metals only on polymer foam precursor and subsequent preparation of foam-based catalysts in aqueous solution or organic electrolyte.To expand the modification horizon,molten salt with wide electrochemical window and fast ion diffusion can achieve the reduction of highly active elements.Herein,we reported is a general and facile method to deposit directly of highly reactive element La and prepare hierarchical honeycomb LaNi_(5) alloy on Ni foam(ho-LaNi_(5)/NF).This self-supporting electrode presents excellent electrical coupling and conductivity between the Ni foam and LaNi_(5),which provides a 3D self-supported heterostructure with outstanding electrocatalytic activity and excellent durability for the hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).It exhibits excellent overpotential(1.86 V)comparable to commercial coupled IrO_(2)//Pt/C(1.85 V)at a high current density of 100 m A cm^(-2).This work may pave the way for fabricating novel 3D self-supported honeycomb alloy that can be applied as electrode for usage of clean energy.

Influence of anions on the adsorption of uranyl on hydroxylated α-SiO_2(001):A first-principles study

The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was studied by the periodic density functional theory(DFT) implemented in the Vienna ab initio simulation package(VASP). For the ligands other than OH^-and PhO^-, 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(—O^-) rather than the protonated one(—O_H), 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 H_2CO_3, H_3PO_4 and H_2O, 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) H20 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.

Preliminary Study of Oxidative Stress in Human Hepatocellular Carcinoma and Adjacent Normal Liver Tissues

OBJECTIVE The antioxidative system in human hepatocellular carcinoma was investigated. METHODS The activities of cytosolic catalase (CAT), superoxide dismu-tase, glutathione peroxidase (GSH-Px), glutathione S-tranferase and levels of reduced glutathione, total protein thiols and malondialdehyde were assayed in 10 cases of hepatocellular carcinoma and adjacent normal liver. RESULTS Hepatoma tissues showed higher activities of CAT, GSH -Px and lower content of total antioxidative capacity compared to adjacent normal liver tissue (P<0.05). CONCLUSION These findings suggest that the antioxidative defense-related enzymes and antioxidants are largely regulated in hepatoma cells. However, the mechanism which is not clear requires further investigation.

饱和碳配体铀化合物的结构及成键性质研究

铀化物的合成已成为金属有机化学领域的研究热点之一。相比于过渡金属化合物,铀化物的合成与分离极具挑战性,尤其是包含铀碳键化合物。碳卡宾具有孤对电子易与铀的空轨道成键,而苄基或烷基中的碳无孤对电子,难以与铀结合,所以饱和碳配体铀化合物的研究较少。随着人们对铀独特的电子结构与成键性质的研究,基于饱和碳配体铀化合物研究取得了一些进展。本综述系统总结了饱和碳配体与不同价态的铀(+3、+4、+5和+6)形成化合物的结构以及成键性质。

Flexible interdigitated layered framework with multiple accessible active sites for high-performance CH_(3)I capture

The development of adsorbent materials for effective capture of radioactive iodomethane(CH_(3)I) from the off-gas of used nuclear fuel reprocessing, remains a significant and challenging line of research because currently state-of-art adsorbents still suffer from low binding affinity with CH_(3)I. Here, we proposed a brand-new adsorption topological structure by developing a 2D interdigitated layered framework, named SCU-20, featuring slide-like channel with multiple active sites for CH_(3)I capture. The responsive rotating-adaptive aperture of SCU-20 enables the optimal utilization of all active sites within the pore for highly selective recognition and capture of CH_(3)I. A record-breaking CH_(3)I uptake capacity of 1.84 g/g was achieved under static sorption conditions with saturated CH_(3)I vapor. Both experimental and theoretical findings demonstrated that the exceptional uptake of SCU-20 towards CH_(3)I can be attributed to the confined physical electrostatic adsorption of F sites, coupled with the chemical nitrogen methylation reaction with uncoordinated N atoms of pyrazine. Moreover, dynamic CH_(3)I uptake capacity potentially allows for the capture of CH_(3)I in simulated real-world off gas reprocessing conditions. This study highlights the potential of SCU-20 as a promising candidate for efficient capture of iodine species and contributes to the development of effective solutions for radioactive iodine remediation.

Tumor Imaging by a^(99m)TcO_(4)^(−)-Labeled Cationic Polymeric Network

Technetium-99m(^(99m)Tc)is the most used(>80%)radionuclide in the clinical nuclear diagnostic imaging procedure.The traditional approach to preparing ^(99m)Tc-based imaging agents utilizes stannous chloride(SnCl_(2))for the reduction of noncomplexing pertechnetate(^(99m)TcO_(4)^(−))to low-valent Tc[e.g.,Tc(IV)].This process,however,is difficult to control precisely and usually results in toxic SnCl_(2) residue and remaining 99mTc(VII),both of which are destructive to humans.Herein,we report a new strategy for preparing^(99m)TcO_(4)^(−)-labeled agents without adding any reductants.The deliberately designed nanoscale cationic polymeric network(SCU-CPN-3)shows excellent affinity for^(99m)TcO_(4)^(−)even at trace levels originating from the strong p-πinteraction with^(99m)TcO_(4)^(−).Impressively,record-fast labeling kinetics are observed,where almost quantitative labeling efficacy(>96%)can be achieved within 1 min,giving rise to a short labeling time and simple operation using a clinical kit.Both single-photon emission computed tomography(SPECT)images and ex vivo biodistribution of different tumor model analyses verify the potential feasibility of this strategy for tumor imaging.

Metal-Organic Framework-Derived Metallic Carbon with Record High Radon Gas Capture Performance

Developing efficient adsorbents for radon(Rn)capture from the ambient environment is of paramount importance for public health.However,it poses a great challenge due to the chemical inertness and extremely low molar concentration of Rn in air.Herein,we report a zeolite imidazolate frameworkderived metallic carbon adsorbent(Zn@NPC)with record high Rn removal performance under ambient conditions.Upon one-step pyrolysis,the prepared Zn@NPC possesses pores with a preference for Rn and atomically dispersed Zn sites,achieving a high Rn removal efficiency that doubles in adsorption coefficient(9.47 L·g^(−1))and triples in adsorption kinetic coefficient(20.25 mL·g^(−1)·min^(−1))over the benchmark Rn adsorbent coconut activated charcoal.Density functional theory calculations elucidate the important role of the metal polarization effect,which cooperates with the pore size confinement effect to boost the overall Rn adsorption performance.This work launches a promising alternative for practical Rn capture.

MXene材料用于放射性元素及重金属离子去除的研究进展

二维过渡金属碳/氮化物(MXene)是2011年发现的一类结构新颖、性质独特的层状纳米材料,目前已被广泛应用于能源存储以及环境治理等领域. MXene材料拥有较大的比表面积、丰富的活性吸附位点、良好的亲水性以及可控的层间距,并且这类纯无机材料表现出优异的抗辐照性能以及良好的导热性能,因此是容纳放射性元素与重金属离子的理想载体.本文归纳总结了近年来MXene材料的可控制备及其对放射性元素和重金属离子的去除研究进展,对相关的实验技术手段、吸附行为与相互作用机理进行了系统梳理,此外还对该领域的发展趋势进行了展望.

Core-shell Au@MnO2 nanoparticles for enhanced radiotherapy via improving the tumor oxygenation

Local hypoxia in solid tumors often results in resistance to radiotherapy （RT）, in which oxygen is an essential element for enhancing DNA damage caused by ionizing radiation. Herein, we developed gold@manganese dioxide （Au@MnO2） core-shell nanoparticles with a polyethylene glycol （PEG） coating as a novel radiosensitizing agent to improve RT efficacy during cancer treatment. In this Au@MnO2 nanostructure, while the gold core is a well-known RT sensitizer that interacts with X-rays to produce charged particles for improved cancer killing under RT, the MnO2 shell may trigger the decomposition of endogenous H2O2 in the tumor microenvironment to generate oxygen and overcome hypoxiaassociated RT resistance. As demonstrated by both in vitro and in vivo experiments, Au@MnO2-PEG nanoparticles acted as effective radiosensitizers to remarkably enhance cancer treatment efficacy during RT. Moreover, no obvious side effects of Au@MnO2-PEG were observed in mice. Therefore, our work presents a new type of radiosensitizer with potential for enhanced RT treatment of hypoxic tumors.

Effects of rare earth elements La and Yb on the morphological and functional development of zebrafish embryos

In recent years,with the wide applications and mineral exploitation of rare earth elements,their potential environmental and health effects have caused increasing public concern.Effect of rare earth elements La and Yb on the morphological and functional development of zebrafish embryos were studied.The embryos were exposed to La3＋ or Yb3＋ at 0,0.01,0.1,0.3,0.5 and 1.0 mmol/L,respectively.Early life stage parameters such as egg and embryo mortality,gastrula development,tail detachment,eyes,somite formation,circulatory system,pigmentation,malformations,hatching rate,length of larvae and mortality were investigated.The results showed La3＋ and Yb3＋ delayed zebrafish embryo and larval development,decreased survival and hatching rates,and caused tail malformation in a concentration-dependent way.Moreover,heavy rare-earth ytterbium led to more severe acute toxicity of zebrafish embryo than light rare-earth lanthanum.

铀催化的氮气活化

氮气约占空气总体积的78%,是大自然赋予人类的宝贵资源。如何实现氮气转化为动植物可利用的含氮化合物,关系着人类的未来和社会的可持续发展。氮气活化,作为一个非常重要的研究领域,一直以来都是科学家面临的重大挑战。目前,低价铀金属有机化合物展现出良好的小分子活化能力。本综述主要介绍了含铀化合物对氮气活化的研究进展,并对其未来进行了展望。

锕系异核双金属化合物

锕系金属有机化合物的研究已成为金属有机化学研究领域的热点之一,其化合物的合成和分离极具挑战性,其中锕系异核双金属化合物在催化和小分子活化方面有潜在的应用前景。随着人们对锕系独特电子结构及其性质的深入认识,锕系异核双金属化合物的研究也取得了一些进展。本文总结了锕系异核双金属化合物近30年的研究成果,主要包括锕系-过渡金属体系和锕系-主族金属体系的实验和理论研究。

铀在有机合成中的应用研究进展

铀储量丰富,是人类未来可持续发展的重要资源.随着人们对铀独特电子结构及其性质的深入认识,铀的资源化及其潜在应用也获得科学家的广泛关注.本文总结了近年来铀在有机合成中的最新研究成果,并对未来发展趋势进行了展望.该综述主要内容包括四价铀和六价铀催化的有机转化研究.

FLiNaK-ThF_(4)的微观结构及热力学性质的深度势能分子动力学研究

钍基熔盐堆是六种第四代先进反应堆之一,深入研究熔盐堆燃料的基础物性对反应堆的安全有效运行和乏燃料后处理意义重大.首先,使用深度神经网络对FLiNaKTh熔盐燃料的力场进行了深度学习,得到了高精度的力场模型.其次,系统研究了FLiNaKTh燃料的配位结构、热力学和动力学性质.径向分布函数和平均力势表明各离子对的相互作用强弱为:Th–F>Li–F>Na–F>K–F,且均随ThF4浓度增大或升温而变弱.在燃料服役温度900 K下,FLiNaK–10 wt.%ThF_(4)体系中Th离子主要以[ThF_(x)]^(4–x)形式存在,Th浓度增大有利于Th离子间形成团簇,导致[Th_(2)F_(x)]^(8–x)和[Th_(3)F_(x)]^(12–x)等占比增大.模拟的扩散系数、热容和密度值与实验值吻合的很好,证明了力场的精确性,进一步预测了0~50wt.%ThF_(4)浓度范围和更多温度下熔盐体系的热物理性质.

Rational design of a cationic polymer network towards record high uptake of ^(99)TcO_(4)^(-)in nuclear waste

^(99)Tc is a long-lived radionuclide present in large amounts as TcO_(4)^(-)-anion in used nuclear fuel.Its removal from the waste stream is highly desirable because of its interference capability with actinide separation and its volatile nature during the nuclear waste vitrification process.Despite the progress achieved in the past few years,the design of anion-exchange materials with optimized Tc uptake property and improved stability under the extreme condition is still a research goal beneficial for reducing the volume of secondary radioactive solid waste generated during the waste partitioning process.However,their design philosophy remains elusive,with challenges coming from charge repulsion,steric hindrance,and insufficient reactive sites within the materials.Herein,we present a design philosophy of cationic polymer network materials for TcO_(4)^(-)separation by systematic precursor screening and structure prediction.This affords an optimized material,SCU-CPN-2(SCU=Soochow University),with extremely high positive charge density while maintaining high radiation resistance.SCU-CPN-2 exhibits a record high adsorption capacity1,467 mg/g towards the surrogate ReO_(4)^(-)compared to all anion-exchange materials reported up to date.In addition to ultrafast adsorption kinetics,SCU-CPN-2 has remarkable selectivity over nitrate and sulfate,and facile recyclability.

Mitochondrial temperature-responsive drug delivery reverses drug resistance in lung cancer

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.

Radiation-induced one-pot synthesis of grafted covalent organic frameworks

Post-synthetic functionalization of covalent organic frameworks(COFs)is an alternative way to enhance and broaden their properties and potential applications.However,the chemical functionalization of COFs is a great challenge because traditional procedures are often time-and energy-consuming,while the crystallinity of COFs can be damaged under harsh conditions.Here we report the in-situ introduction of functional graft chains onto the skeleton of COFs during the synthesis process through the combination of radiation-induced synthesis and graft polymerization techniques under ^(60)Co gamma-ray radiation.The synthesis and functionalization of COFs are simultaneously accomplished in a chemical system under ambient conditions yielding a large number of different functionalized COFs.The obtained carboxyl-functionalized COFs exhibit excellent radioactive uranium removal capabilities from aqueous solution with fast uptake dynamics,high adsorption capacity,and excellent selectivity over other competing metal ions.