The biological mode of action of artemisinin, a potent antimalarial, has long been controversial. Previously we established a yeast model addressing its mechanism of action and found mitochondria the key in executing artemisinin's action. Here we present data showing that artemisinin directly acts on mitochondria and it inhibits malaria in a similar way as yeast. Specifically, artemisinin and its homologues exhibit correlated activities against malaria and yeast, with the peroxide bridge playing a key role for their inhibitory action in both organisms. In addition, we showed that artemisinins are distributed to malarial mitochondria and directly impair their functions when isolated mitochondria were tested. In efforts to explore how the action specificity of artemisinin is achieved, we found strikingly rapid and dramatic reactive oxygen species (ROS) production is induced with artemisinin in isolated yeast and malarial but not mammalian mitochondria, and ROS scavengers can ameliorate the effects of artemisinin. Deoxyartemisinin, which lacks an endoperoxide bridge, has no effect on membrane potential or ROS production in malarial mitochondria. OZ209, a distantly related antimalarial endoperoxide, also causes ROS production and depolarization in isolated malarial mitochondria. Finally, interference of mitochondrial electron transport chain (ETC) can alter the sensitivity of the parasite towards artemisinin. Addition of iron chelator desferrioxamine drastically reduces ETC activity as well as mitigates artemisinin-induced ROS production. Taken together, our results indicate that mitochondrion is an important direct target, if not the sole one, in the antimalarial action of artemisinins. We suggest that fundamental differences among mitochondria from different species delineate the action specificity of this class of drugs, and differing from many other drugs, the action specificity of artemisinins originates from their activation mechanism.

No abstract

MXene combining high metal-like conductivity, high hydrophilicity, and abundant surface functional groups has been recognized as a class of versatile two-dimensional materials for many applications. However, the aggregation of MXene nanosheets from interlayer van der Waals force and hydrogen bonds represents a major problem that severely limits their practical use. Here, we report an aerogel structure of MOFs@ MXene, in which the in situ formed MOF particles can effectively prevent the accumulation of MXene, enabling a three-dimensional (3D) hierarchical porous conductive network to be composed with an ultralight feature. Subsequently, a 3D porous MXene aerogel threaded hollow CoS nanobox composite ((CoS NP@NHC)@MXene) derived from the MOFs@MXene aerogel precursor was synthesized, and the highly interconnected MXene network and hierarchical porous structure coupled with the ultrafine nanocrystallization of the electrochemically active phase of CoS yield the hybrid system with excellent electron and ion transport properties. Benefiting from the synergistic effect of the components, the (CoS NP@NHC)@MXene composite manifests outstanding electrochemistry properties as electrode materials for all of the lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (PIBs). It demonstrated the excellent cycle stability and high capacities of 1145.9 mAh g −1 at 1 A g −1 after 800 cycles and 574.1 mAh g −1 at 5 A g −1 after 1000 cycles for LIBs, 420 mAh g −1 at 2 A g −1 after 650 cycles for SIBs, and 210 mAh g −1 at 2 A g −1 after 500 cycles for PIBs. First-principle calculations confirmed that the (CoS NP@NHC)@MXene hybrid could enhance the charge transfer reaction kinetics, particularly at the interface. More importantly, the excellent rate performance under high mass loading and the high volumetric energy and power density of the entire electrode represent the potential of (CoS NP@NHC) @MXene composites for applications to practical electrochemical energy storage devices. The synthesis method reported in this Article is versatile and can be easily extended to produce other porous MXene-aerogel-based materials for various applications.

Magnetoelectric multiferroics have received much attention in the past decade due to their interesting physics and promising multifunctional performance. For practical applications, simultaneous large ferroelectric polarization and strong magnetoelectric coupling are preferred. However, these two properties have not been found to be compatible in the single-phase multiferroic materials discovered as yet. Here, it is shown that superior multiferroic properties exist in the A-site ordered perovskite BiMn Cr O synthesized under high-pressure and high-temperature conditions. The compound experiences a ferroelectric phase transition ascribed to the 6s lone-pair effects of Bi at around 135 K, and a long-range antiferromagnetic order related to the Cr spins around 125 K, leading to the presence of a type-I multiferroic phase with huge electric polarization. On further cooling to 48 K, a type-II multiferroic phase induced by the special spin structure composed of both Mn- and Cr-sublattices emerges, accompanied by considerable magnetoelectric coupling. BiMn Cr O thus provides a rare example of joint multiferroicity, where two different types of multiferroic phases develop subsequently so that both large polarization and significant magnetoelectric effect are achieved in a single-phase multiferroic material.

The magnetoelectric multiferroicity is not expected to occur in a cubic perovskite system due to the high structural symmetry. By versatile measurements in magnetization, dielectric constant, electric polarization, neutron and X-ray diffraction, Raman scattering as well as theoretical calculations, we reveal that the A-site ordered perovskite LaMn 3 Cr 4 O 12 with cubic symmetry is a novel spin-driven multiferroic system with strong magnetoelectric coupling effects. When magnetic field is applied in parallel/perpendicular to electric field, the ferroelectric polarization can be enhanced/suppressed significantly. The unique multiferroic phenomenon observed in this cubic perovskite cannot be understood by conventional spin-driven microscopic mechanisms. Instead, a nontrivial effect involving the interactions between two magnetic sublattices is likely to play a crucial role. 3The magnetoelectric (ME) multiferroicity with coupled ferroelectric and magnetic orders have received much attention due to their great potential for numerous applications [1][2][3][4][5][6][7][8]. Perovskite is one of the most important material systems for multiferroic study. Since the discovery of multiferroic behaviors in perovskite BiFeO 3 and TbMnO 3 [2,3], a large number of multiferroic materials with different physical mechanisms have been found in the last decade [9][10][11][12][13]. Among them, the spin-induced multiferroics have received the most attention because the ferroelectricity is induced by magnetic structures so that a strong ME coupling would be expected [14][15][16]. Several theories such as spin-current model (or inverse Dzyaloshinskii-Moriya interaction), exchange striction mechanism and d-p hybridization mechanism have been proposed to account for the spin-induced ferroelectricity in ME multiferroics by special spin textures such as non-collinear spiral spin structures and collinear E-type antiferromagnetic (AFM) structure with zigzag spin chains [17][18][19][20][21]. It is well known that a cubic perovskite lattice is unfavorable for ferroelectricity due to the existence of an inversion center. However, the total symmetry for an ME multiferroics is the product of the crystal and magnetic symmetries. Therefore, in principle, it is possible to find an ME multiferroics in a cubic perovskite system if its magnetic structure breaks the space inversion symmetry. Nevertheless, such an intriguing case has never been found in previous studies. 4The A-site ordered perovskite with a chemical formula of AA′ 3 B 4 O 12 provides an opportunity for searching ME multiferroics in a cubic lattice.This type of ordered perovskite can be formed when three quarters of the A-site of a simple ABO 3 perovskite is substituted by a transition-metal ion A′ (Fig. 1a) [22]. Since both A′ and B sites accommodate magnetic transition-metal ions, multiple magnetic interactions may develop while the crystal structure can be finely tuned by selecting appropriate A′ and B elements to maintain a cubic lattice [23][24][25][26][27]. In this lette...

The first-principles method is challenged by accurate prediction of van der Waals interactions, which are ubiquitous in nature and crucial for determining the structure of molecules and condensed matter. We have contributed to this by constructing a set of pseudopotentials and pseudoatomic orbital basis specialized for molecular systems consisting of C/H/N/O elements. The reliability of the present method is verified from the interaction energies of 45 kinds of complexes (comparing with CCSD(T)) and the crystalline structures of 23 kinds of typical explosive solids (comparing with experiments). Using this method, we have studied the phase transition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under static compression up to 50 GPa. Kinetically, intramolecular deformation has priority in the competition with intermolecular packing deformation by ∼87%. A possible γ → β phase transition is found at around 2.10 GPa, and the migration of HO has an effect of kinetically pushing this process. We make it clear that no β → δ/ε → δ phase transition occurs at 27 GPa, which has long been a hot debate in experiments. In addition, the P-V relation, bulk modulus, and acoustic velocity are also predicted for α-, δ-, and γ-HMX, which are experimentally unavailable.

To study the metal/semiconductor interface by means of atomistic simulation, an effective interfacial potential is an important issue. In this work, ab initio adhesive energies are used to derive interfacial potentials for the Al/SiC(111) interface. In order to describe the directional covalent bonds at the interface, we suggest a potential model comprising both two-body and three-body terms. The former is a parameter-free potential obtained by a lattice inversion method and the latter is assigned in modified Stillinger-Weber potential form. The obtained potentials are used to study the position of misfit dislocations in the Al/SiC(111) interface. There is a coherent Al interlayer on the interface plane and the dislocation appears on the Al side.

Three-dimensional beehive-like hierarchical porous carbons (HPCs) have been prepared by a facile carbonization of polymethylmethacrylate (PMMA)/ polyacrylonitrile (PAN) core-shell polymer particle followed by KOH activation. The all-organic porogenic core-shell precursor was synthesized by a simple and green surfactant-free emulsion polymerization. The as-obtained HPCs show favorable features for electrochemical energy storage such as high specific surface area of up to 2085 m 2 g -1 , high volume of pores up to 1.89 cm 3 g -1 , hierarchical porosity consisting of micro, meso, and macropores, turbostratic carbon structure, uniform pore size and rich oxygen-doping (21.20 %). The supercapacitor performance of HPCs exhibit a high specific capacitance 314 F g -1 at a current density of 0.5 A g -1 and 237 F g -1 at a current density of 20 A g -1 , ultra-high rate capability with 83% retention rate from 1 to 20 A g -1 and outstanding cycling stability with 96% capacitance retention after 2000 cycles. The facile, efficient and green synthesis strategy for novel HPCs from polymer sources could find use in supercapacitors, lithium ion batteries , fuel cells and sorbents.