Dynamic Structural Fluxionality in a Planar Tetracoordinate Carbon Cluster Stabilized by Boron Ligands.

The design of boron-based molecular rotors stems from boron-carbon binary clusters containing multiple planar hypercoordinate carbons (phCs, such as CB). However, the design of boron-coordinated phCs is challenging due to boron's tendency to occupy hypercoordinate centers more than carbon. Although this challenge has been addressed, the designed clusters of interest have not exhibited dynamic fluxionality similar to that of the initial CB.

CBe H : Unprecedented 2σ/2π Double Aromaticity and Dynamic Structural Fluxionality in a Planar Tetracoordinate Carbon Cluster.

A 14-electron ternary anionic CBe H cluster containing a planar tetracoordinate carbon (ptC) atom is designed herein. Remarkably, it can be stabilized by only two beryllium atoms with both π-acceptor/σ-donor properties and two hydrogen atoms, which means that the conversion from planar methane (transition state) to ptC species (global minimum) requires the substitution of only two hydrogen atoms. Moreover, two ligand H atoms exhibit alternate rotation, giving rise to interesting dynamic fluxionality in this cluster.

[Effect of Sunitinib on Pyroptosis of Drug-Resistant Leukemia K562/ADR Cells and Its Pathway].

Objective: To investigate the inducing effect of sunitinib on the death of drug-resistant leukemia K562/ADR cells and the related signaling pathway.

Methods: K562/ADR cells were treated with different concentrations of sunitinib, and the cells were collected at 24, 48, 72, and 96 hours, respectively. MTS assay was used to detect the effect of sunitinib on the proliferation of K562/ADR cells, and the appropriate sunitinib intervention time and concentration were determined.

Boron-based PdB alloy cluster as a nanoscale antifriction bearing system: tubular core-shell structure, double π/σ aromaticity, and dynamic structural fluxionality.

Boron-based nanoclusters show unique geometric structures, nonclassical chemical bonding, and dynamic structural fluxionality. We report here on the theoretical prediction of a binary PdB cluster, which is composed of a triangular Pd core and a tubular double-ring B unit in a coaxial fashion, as identified through global structural searches and electronic structure calculations. Molecular dynamics simulations indicate that in the core-shell alloy cluster, the B double-ring unit can rotate freely around its Pd core at room temperature and beyond.

Chemical Bonding and Dynamic Structural Fluxionality of a Boron-Based NaB Sandwich Cluster.

Doping alkali metals into boron clusters can effectively compensate for the intrinsic electron deficiency of boron and lead to interesting boron-based binary clusters, owing to the small electronegativity of the former elements. We report on the computational design of a three-layered sandwich cluster, NaB, on the basis of global-minimum (GM) searches and electronic structure calculations. It is shown that the NaB cluster can be described as a charge-transfer complex: [Na][B][Na].

The dodeca-coordinated La©BC molecular wheels: conflicting aromaticity double aromaticity.

The transition-metal centered boron molecular wheels have attracted the attention of chemists. The highest deca-coordination number for central metal atoms was observed in Ta©B and Nb©B molecular wheels. Here, we report a theoretical study of La©BC ( = +1, 0, -1) clusters with the dodeca-coordinated La atom.

BeB cluster: a dynamically fluxional beryllo-borospherene.

The beryllium-doped BeB cluster has two nearly isoenergetic isomers, adopting the smallest trihedral spherical geometries with a boron single-chain skeleton. The B skeleton in the global minimum (, A) comprises three conjoined boron rings (one B/two B) on the waist, sharing two B equilateral triangles at the top and bottom, respectively. However, the local minimum (, A') has one deformed B pyramid at the top.

Y©BC cluster: a boron-carbon molecular wheel with dodeca-coordination number in plane.

Computational evidence is reported for the largest planar molecular wheel of the Y©BC cluster, featuring an yttrium atom enclosed by a highly symmetric BC ring. The BC ring is viable in the -(BCB)- form with double 9/10 aromaticity. The centered yttrium atom is dodeca-coordinated with the peripheral BC ring, which sets a record coordination number for a planar structure in chemistry heretofore.

Bare and ligand protected planar hexacoordinate silicon in SiSbM (M = Ca, Sr, Ba) clusters.

The occurrence of planar hexacoordination is very rare in main group elements. We report here a class of clusters containing a planar hexacoordinate silicon (phSi) atom with the formula SiSbM (M = Ca, Sr, Ba), which have (A') symmetry in their global minimum structure. The unique ability of heavier alkaline-earth atoms to use their vacant d atomic orbitals in bonding effectively stabilizes the peripheral ring and is responsible for covalent interaction with the Si center.

The unique sandwich KBeBH cluster with a real borozene BH core.

Theoretical evidence is reported for a boron-based KBeBH sandwich cluster, showing a perfectly BH ring, being capped by two tetrahedral KBe ligands. Due to the comfortable charge transfer, the sandwich is viable in [KBe][BH][BeK] ionic complex in nature. The [BH] core with 6π aromaticity vividly imitates the benzene (CH), occurring as a real borozene.

A new species of the Genus Pelodiscus Fitzinger, 1835 (Testudines: Trionychidae) from Huangshan, Anhui, China.

A new species of the soft-shelled turtle genus Pelodiscus is described based on seven specimens from Huangshan, southern Anhui Province, China. The new species, Pelodiscus huangshanensis sp. nov.

Forensic nanopore sequencing of STRs and SNPs using Verogen's ForenSeq DNA Signature Prep Kit and MinION.

The MinION nanopore sequencing device (Oxford Nanopore Technologies, Oxford, UK) is the smallest commercially available sequencer and can be used outside of conventional laboratories. The use of the MinION for forensic applications, however, is hindered by the high error rate of nanopore sequencing. One approach to solving this problem is to identify forensic genetic markers that can consistently be typed correctly based on nanopore sequencing.

Anchoring a bow-shaped boron single chain in binary BeB cluster: hybrid octagonal ring, multifold π/σ aromaticity, and dual electronic transmutation.

Elemental boron clusters do not form linear chain or monocyclic ring structures, which is in contrast to carbon. Based on computer global searches and quantum chemical calculations, we report on the viability of a curved boron single chain in binary Be6B7- cluster. The boron motif assumes a bow shape, being anchored on a Be6 prism.

Boron-based ternary RbBeB cluster featuring unique sandwich geometry and a naked hexagonal boron ring.

Computational evidence is reported on a boron-based ternary Rb6Be2B6 cluster as the "Big Mac" sandwich on a subnanoscale with thickness of 0.58 nm. The core hexagonal B6 ring, occurring in the naked form due to double 6π/6σ aromaticity, is capped by two tetrahedral BeRb3 ligands.

Planar or tetrahedral? A ternary 17-electron CBeH cluster with planar pentacoordinate carbon.

A 17-electron CBeH cluster features planar pentacoordinate carbon, owing to the 2π/6σ double aromaticity. The neutral CBeH cluster has a tetrahedral configuration despite its 18-electron counting. The latter species is governed by σ conjugation.

Boron-Based Chiral Helix Be B and Be B Clusters: Structures, Chemical Bonding, and Formation Mechanism.

Boron forms a rich variety of low-dimensional nanosystems, including the newly discovered helix Be B (1) and Be B (2) clusters. We report herein on the elucidation of chemical bonding in clusters 1/2, using the modern quantum chemistry tools of canonical molecular orbital analyses and adaptive natural density partitioning (AdNDP). It is shown that clusters 1/2 contain a chiral helix Be B Be or Be B Be skeleton with a total of 11 and 12 segments, respectively, which effectively curve into "helical pseudo rings" and chemically consist of two "quasicircles" as defined by their anchoring Be centers.

Ternary 12-electron CBeX (X = H, Li, Na, Cu, Ag) clusters: planar tetracoordinate carbons and superalkali cations.

Molecules with planar tetracoordinate carbons (ptCs) are exotic in chemical bonding, and they are normally designed according to the 18-electron rule. Here we report on the viability of ptC clusters with as few as 12 valence electrons, which represent the lower limit in terms of electron counting. Specifically, we have computationally designed a class of ternary 12-electron ptC clusters, CBe3X3+ (X = H, Li, Na, Cu, Ag), based on a rhombic CBe32- unit.

Sandwich-type NaB and NaB clusters: charge-transfer complexes, four-fold π/σ aromaticity, and dynamic fluxionality.

Boron-based clusters possess unusual structural and bonding properties owing to boron's electron-deficiency. We report on the theoretical prediction of two binary B-Na clusters, Na6B7- and Na8B7+, which assume unique sandwich geometries, featuring a perfectly planar B7 wheel and two triangular Na3 or quasi-tetrahedral Na4 ligands. Despite distinct electronegativities of B/Na, the B-Na clusters do not form typical salts.

Divide and Stack Up: Boron-Based Sandwich Cluster as a Subnanoscale Propeller.

Typical salts are composed of positive and negative ions that appear alternatively, whereas decorated layered materials normally have ions anchored on the polygonal sites. In this way, the ions are spatially fixed and the system is stabilized on electrostatic grounds. Here we report on a unique boron-lithium cluster, B Li , which contains a disk-like B core, being sandwiched by a Li ring and an isolated Li atom.

Boron-based inorganic heterocyclic clusters: electronic structure, chemical bonding, aromaticity, and analogy to hydrocarbons.

This Perspective article deals with recent computational and experimental findings in boron-based heterocyclic clusters, which focuses on binary B-O and B-S clusters, as well as relevant ternary B-X-H (X = O, S, N) species. Boron is electron-deficient and boron clusters do not form monocyclic rings or linear chains. Boron-based heterocyclic clusters are intuitively even more electron-deficient and feature exotic chemical bonding, which make use of O 2p, S 3p, or N 2p lone-pairs for π delocalization over heterocyclic rings, facilitating new cluster structures and new types of bonding.

The complete mitochondrial genome of (Testudines: Trionychidae).

The complete mitochondrial genome sequence of was determined by shotgun sequencing. The total length of mitogenome is 16,593 bp, and contains 13 protein-coding genes, 22 tRNA genes, 2 ribosome RNA genes, and 1 control region. Most of the genes of .

Starting a subnanoscale tank tread: dynamic fluxionality of boron-based BCa alloy cluster.

Alloying an elongated B cluster with Ca is shown to give rise to a dynamically fluxional BCa cluster, the latter behaving like a tank tread at the subnanoscale. Computer global search identifies the BCa (A) global-minimum structure, which is chiral in nature and retains the quasi-planar moiety of bare B cluster with Ca capped at one side, forming a half-sandwich. The rotation barrier of BCa cluster is reduced with respect to B by one order of magnitude, down to 1 kcal mol at the PBE0/6-311+G* level, which demonstrates structural fluxionality at 600 K and beyond molecular dynamics simulations.

Planar Pentacoordinate versus Tetracoordinate Carbons in Ternary CBeLi and CBeLi Clusters.

Planar hypercoordinate carbon molecules are exotic species, for which the 18-electron counting has been considered a rule. We report herein computational evidence of perfectly planar C CBeLi (1) and D CBeLi (3) clusters. These ternary species contain 16 and 18 electrons, respectively.

Boron-based binary BeB cluster: three-layered aromatic sandwich, electronic transmutation, and dynamic structural fluxionality.

Boron-based nanoclusters have unique structures, bonding, and dynamic properties, which originate from boron's electron-deficiency. We demonstrate here that pouring in extra electrons can alter such systems fundamentally. A coaxial triple-layered Be6B102- sandwich cluster is designed via global structural searches and quantum chemical calculations.

[Case analysis and control strategy of imported malaria in Qingcheng District, Qingyuan City from 2011 to 2016].

Objective: To understand the characteristics of imported malaria cases in Qingcheng District, Qingyuan City and explore the strategies and priorities in prevention and control, so as to provide the evidence for improving the diagnosis, treatment and management of imported malaria.

Methods: The data of imported malaria as well as the case epidemiological investigations were collected and retrospectively analyzed for the species composition, original countries, population distribution, regional distribution, onset situation, diagnosis, treatment, etc. in Qingcheng District from 2011 to 2016.