Low-coordinated surface sites make truncated Pd tetrahedrons as robust ORR electrocatalysts outperforming Pt for DMFC devices

Developing highly stable and active non-Pt oxygen reduction reaction(ORR)electrocatalysts for power generation device raises great concerns and remains a challenge.Here,we report novel truncated Pd tetrahedrons(T-Pd-Ths)enclosed by{111}facets with excellent uniformity,which have both low-coordinated surface sites and distinct lattice distortions that would induce“local strain”.In alkaline electrolyte,the T-Pd-Ths/C achieves remarkable ORR specific/mass activity(SA/MA)of 2.46 mA·cm^(−2)/1.69 A·mgPd^(−1),which is 12.3/16.9 and 10.7/14.1 times higher than commercial Pd/C and Pt/C,respectively.The T-Pd-Ths/C also exhibits high in-situ carbon monoxide(CO)tolerance and 50,000 cycles durability with an activity loss of 7.69%and morphological stability.The rotating ring-disk electrode(RRDE)measurements show that a 4-electron process occurs on T-PdThs/C.Theoretical calculations demonstrate that the low-coordinated surface sites contribute largely to the enhancement of ORR activity.In actual direct methanol fuel cell(DMFC)device,the T-Pd-Ths/C delivers superior open-circuit voltage(OCV)and peak power density(PPD)to commercial Pt/C from 25 to 80℃,and the maximum PPD can reach up to 163.7 mW·cm−2.This study demonstrates that the T-Pd-Ths/C holds promise as alternatives to Pt for ORR in DMFC device.

The QCD Ground State Chiral Tetrahedron Symmetry

We propose that the exotic meson tetraquark ud~dũintroduced in previous papers, may be a pseudo-Goldstone boson having a tetrahedron geometry and symmetry. The transition from the neutral pion superposition of two free mesons, dd~ and uũ, to the tetrahedron geometry with optional two chiral states may be the symmetry breaking of the QCD ground state. The ud~dũtetrahedron mass may be calculated by measuring the β decay rate variability. We assume that electrons and positrons are composite particle exotic tetraquarks, dũdd~ for the electrons and ud~dd~ for the positrons and confined by the strong force. We propose that the QCD tetrahedrons play a central role in electron pairing mechanism in both chemical bond forming and superconductor Cooper pairs. We propose a hypothesis where the QCD ground state tetrahedrons play a central role in low energy physics where quark exchange reactions between particles and the QCD tetrahedrons via gluon junctions transfer all the forces. The QCD ground state ud~dũtetrahedrons hypothesis provides a symmetry breaking and a mass gap may be created by the ground state QCD tetrahedrons Bose-Einstein condensate.

Un-thorough Delaunay Approach for Tetrahedral Mesh Generation

An integrated tetrahedrization algorithm in 3D domain which combines the Delaunay tetrahedral method with un-Delaunay tetrahedral method is described. The algorithm was developed by constructing Delaunay Tetrahedrons from a scattered point set, recovering boundaries using Delaunay and un-Delaunay method, inserting additional nodes in unsuitable tetrahedrons, optimizing tetrahedrons and smoothing the tetrahedral mesh with the 2D-3D Laplacian method. The algorithm has been applied to the injection molding CAE preprocessing.

Structure and Pozzolanic Activity of Calcined Coal Gangue during the Process of Mechanical Activation

On the basis of analyzing coal gangue＇s chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

Crystal Structure and Antitumor Activity of Tri[2- [N-(4'-methyl-benzylsulfonyl)amino]ethyl]-amine

The crystal structure of the title compound (C27H38N4O7S3, Mr = 626.79) has been determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group Pīwith a = 9.411(1), b = 11.645(2), c = 14.672(2) , a = 91.80(1), b = 95.36(1), g =104.56(1)o, V = 1547.0 3, Z = 2, Dc = 1.346 g/cm3, l = 0.71073 , m(MoKa) = 0.289 mm-1 and F(000) = 664. The structure was refined to R = 0.0406 and wR = 0.1177 for 4103 observed reflections with I > 2s(I). X-ray diffraction analysis reveals that the title compound is a practically distorted tetrahedron and each molecule contains one lattice H2O by hydrogen bond. The antitumor activity of the title compound against HL-60 human leukemia cells has also been studied by MTT method.

The Optical Resolution of Chiral Tetrahedrone-type Clusters Contai- ning SCoFeM (M=Mo or W) Using High Performance Liquid Chromatography Chiral Stationary Phase

Amylose tris (phenylcarbamate) chiral stationary phase (ATPC-CSP) was prepared and used for optical resolution of clusters 1 and 2. n-Hexane/2-propanol ( 99/1; v/v) were found to be the most suitable mobile phase on ATPC-CSP.

Kinematics Analysis of Motion Simulation Subsystem for Unmanned Vehicle

Unmanned vehicle has attracted wide attention and interests throughout the world since it first deputed in the 1960s. However, the experimental methods for unmanned vehicle＇s intelligent behavior, such as semi-physical simulation and motion subsystem, have not been widely explored. First, the requirements of the motion subsystem in unmanned vehicle semi-physical facility are analyzed, and a six DOF parallel manipulator is selected to reproduce the pose of the vehicle. The link lengths of the motion subsystem are worked out under the given rotational angles of the vehicle. According to the geometric properties of tetrahedron, three joint positions of the top platform are determined, and the rest are obtained from the first three position vectors. Six constraint equations are set up based on the vertices on the top platform and the link lengths. In order to solve the six angle variables, a numerical algorithm built on the Newton-Raphson iterative method is presented, which is based on Taylor series expansion of six constraint equations. The pose of the top platform is ultimately calculated. The eigenvalues of the top platform are solved to obtain the natural frequencies of the motion subsystem. The coordinates of six joint centers on the top platform and six constraint equations can be realized by simple algebraic manipulation, which allows significant abbreviation in the formulation and provides a systematic way of obtaining the kinematic solution of the parallel manipulator. A numerical example is given and its efficacy is demonstrated by the inverse kinematics. The computation strategy based on tetrahedron method and Newton-Raphson iterative method provide a simple and cost-effective method for solving forward kinematics of six DOF parallel manipulators, and this method sheds light on other parallel manipulators.

Discrete Differential Geometry of <i>n</i>-Simplices and Protein Structure Analysis

This paper proposes a novel discrete differential geometry of n-simplices. It was originally developed for protein structure analysis. Unlike previous works, we consider connection between space-filling n-simplices. Using cones of an integer lattice, we introduce tangent bundle-like structure on a collection of n-simplices naturally. We have applied the mathematical framework to analysis of protein structures. In this paper, we propose a simple encoding method which translates the conformation of a protein backbone into a 16-valued sequence.

Tetrahedral DNA Nanostructure-modified Gold Nanorod-based Anticancer Nanomaterials for Combined Photothermal Therapy and Chemotherapy

Objective To develop an effective treatment strategy to simultaneously avoid fatal adverse effects in the treatment of oral cancer,combination therapy has been explored because of its multiple functions.This work aims to develop a novel type of gold-nanorod-based nanomaterials decorated with tetrahedral DNA nanostructures(TDN)carrying antitumor drugs,namely,GNR@TDN-DOX nanocomposites.Methods In the designed structure,TDN,with a three-dimensional geometry composed of DNA strands,can provide GC base pairs for binding with the anticancer drug doxorubicin(DOX).The photothermal heating properties,biocompatibility properties,and antitumor performance of obtained GNR@TDN-DOX nanocomposites were investigated to assess their application potential in tumor treatment.Results Systematic studies have shown that the obtained GNR@TDN-DOX nanocomposites have high photothermal conversion under the illumination of an 808-nm infrared laser,leading to effective antitumor applications.In addition,the cell viability study shows that GNR@TDN-DOX nanocomposites have good biocompatibility.In vitro studies based on A375 cells show that the GNR@TDN-DOX nanocomposites can effectively eliminate cancer cells because of the combination of photothermal therapy induced by GNRS and chemotherapy induced by TDN-carrying DOX.The result shows that the obtained GNR@TDN-DOX nanocomposites have efficient cellular uptake and lysosome escape ability,together with their nuclear uptake behavior,which results in a significant antitumor effect.Conclusion This work has demonstrated a potential nanoplatform for anticancer applications.

Synthesis and Crystal Structure of a Novel Tetravanadate Modified by Chiral Racemoid Zirconium Complex

[Zr（phen）4（H2O）4O2（V4O12）]（phen）2 1 （phen = 1,10-phenanthroline） was synthesized under hydrothermal condition. The crystal of 1 belongs to triclinic, space group P1^- with a = 10.6334（8）, b = 11.9201（8）, c = 14.6505（10） A, α = 69.9980（10）, β = 84.9240（10）, γ = 84-1300（10）°, V = 1733.0（2） A^3, Z = 1, Mr = 1672.27, Dc = 1.602 g/cm^3, C72H56N12O18V4Zr, F（000） = 848, μ（MoKa） = 0.747 mm^-1, S = 0.957, R = 0.0504 and wR = 0.1173 for 4011 observed reflections （1 〉 20（I））. The crystal structure of 1 could be discussed in terms of {Zr（phen）2（H2O）2O2}, un-coordinated 1,10-phenanthroline molecules and { V4O12 } unit. In { Zr（phen）2（H2O）2O2 }, the coordination geometry of zirconium is a dodecahedron, but {V4O12} unit is constructed from four apex-sharing {VO4} tetrahedra. Furthermore, {V4O12} links with two {Zr（phen）2（H2O）2O2} units via two bridging oxygen atoms. Interestingly, the two {Zr（phen）2（H2O）2O2} units display D- and L-enantiomers, respectively, upon which the whole molecule represents a racemoid configuration.

STUDY ON MAXIMUM HYDROGEN CAPACITY FOR Zr-Ni AMORPHOUS ALLOY

To design the amorphous hydrogen storage alloy efficiently, the maximum hydrogen capacities for Zr - Ni amorphous alloy were calculated. Based on the Rhomb Unit Structure Model(RUSM) for amorphous alloy and the experimental result that hydrogen atoms exist in 3Zr1Ni and 4Zr tetrahedron interstices in Zr-Ni amolphous alloy, the numbers of 3Zr-1Ni and 4Zr tetrahedron interstices in a RUSM were calculated which correspond to the hydrogen capacity. The two extremum Zr distribution states were calculated, such as highly heterogeneous Zr distribution and homogeneous Zr distribution. The calculated curves of hydrogen capacity with different Zr contents at two states indicate that the hydrogen capacity increases with increasing Zr content and reaches its maximum when Zr is 75%. The theoretical maximum hydrogen capacity for Zr - Ni amorphous alloy is 2.0 (H/M). Meanwhile, the hydrogen capacity of heterogenous Zr distribution alloy is higher than that of homogenous one at the same Zr content. The experimental results prove the calculated results reasonable, and accordingly, the experimental results that the distribution of Zr atom in amorphous alloy occur heterogeneous after a few hydrogen absorption desorption cycles can be explained.

Preliminary Discussion on the Refinement Mesh Generation for Adaptive Analysis

In recent years, due to the rapid development of computer hardware and the urgent need of complex engineering problems, great support has been provided in the related fields of unstructured mesh generation. A large number of research results show that the adaptive analysis is an effective way to improve the efficiency and precision of the numerical calculation. The reliable error estimation and the powerful mesh generation are two key problems in the process of adaptive numerical analysis. H-type refinement strategy adding the new nodes in the high error area, gradually refines the mesh to reduce the size of the element to achieve the purpose of mesh adaptation;this strategy is simple, intuitive and easy to program. Although the calculation accuracy of unstructured triangle and tetrahedron elements is not high, these elements are suitable for discretization of any complex problem domain, and have a wider range of application in academic and engineering fields.

Numerical Experiment for Dipole-Dipole Interaction in Electro-Magnetism with Help of a Regular Tetrahedron

Aim of this work is to try to explain, on a Rational basis, some equations of Electro-Magnetism, which are based on Experimental data. Any Electric Field can produce a Field of many small Electric Dipoles, continuously distributed in space. In a region, where the Electric Field is constant, in direction and magnitude, all the small Dipoles are parallel to the Electric Field, and are represented by a single, long, parallel to them, fixed in space, Electric Dipole, which is here called Compass. An Alternating current, in a straight Conductor, is studied, by a simple, short computer program, for step-by-step nonlinear dynamic analysis. It is found that, only an Alternating current, not a direct current, can produce an Electric Dipole, in a straight Conductor. The two above Dipoles (Compass-Conductor) are assumed with equal lengths &#8467;, lying on two skew lines, perpendicular to each other, at a distance &#8467;√2, thus forming, by their four ends, a Regular Tetrahedron, with side length &#8467;. Repulsion, between Like Charges, obeys the simple Coulomb Electro-Static law. Whereas Interaction (Attraction or Repulsion), between Unlike Charges, obeys a more accurate Lennard-Jones law. The analysis of Dipole-Dipole (Compass-Conductor) Interaction is performed by hand calculator. The only out-of-balance forces, in the regular Tetrahedron, acting on the Rigid Conductor, are the so-called magnetic forces. Their direction is found, in a simple Rational way, with help of Regular Tetrahedron, without recoursing to a “right-hand-rule”. The proposed model is applied to 1) The force acting on an Electric Charge moving in a magnetic field. 2) The force acting on a Current carrying straight Conductor, due to a magnetic field. 3) The magnetic fields created around a Current carrying straight Conductor. In these applications, proposed model gives reasonable results. Particularly, in third application, results, obtained by proposed model, are found in satisfactory approximation with corresponding ones, obtained by an empirical formula, based on relevant Experimental observations of H.-C. Oersted and A.-M. Ampère. So, the reliability of proposed model is checked. Position and direction of magnetic field vector coincide with those of a corresponding fixed Compass of a constant Electric Field. Main point of present work is that, without introducing the concept of a magnetic field vector, by combining field of dipoles, produced by an electric field, with dipole of an alternating current carrying conductor, the magnetic forces can be determined.

An Upwind Finite Volume Element Method for Nonlinear Convection Diffusion Problem

A class of upwind finite volume element method based on tetrahedron partition is put forward for a nonlinear convection diffusion problem. Some techniques, such as calculus of variations, commutating operators and the a priori estimate, are adopted. The a priori error estimate in L2-norm and H1-norm is derived to determine the error between the approximate solution and the true solution.

6D MEASURING TECHNOLOGY AND METHOD OF COORDINATE TRANSFORMATIONS IN THE AUTOMOBILE BODY-IN-WHITE MEA

A new high accuracy 6D ( Dimension ) wide range measuring technology and the method of coordinate transformations have been developed in a project for automobile body-in- white measurement in Michigan , U S A . The requirements and the special features about the measured objective are mainly stated. The main instruments used in the project are introduced. The 6D measuring system , the method for coordinate transformations and the design of 3D optical target with hollow tetrahedron are described in detail . The 6D system and the technology can be certainly used in many other kinds of geometric mea- suring projects .

The Right Triangle as the Simplex in 2D Euclidean Space, Generalized to n Dimensions

The purpose of the research is to show that the general triangle can be replaced by the right-angled triangle as the 2D simplex, and this concept can be generalized to any higher dimensions. The main results are that such forms do exist in any dimensions;meet the requirements usually placed on an n-dimensional simplex;a hypotenuse and legs can be defined in these shapes;and a formula can be given to calculate the volume of the shape solely from the legs by a direct generalization of the Pythagorean Theorem, without computing the Cayley-Menger determinant.

浅谈塑料离合踏板臂使用Tetrahedron有限元网格的后处理

汽车轻量化为节能减排作出了巨大贡献,而“以塑代钢”是轻量化中很常用的途径。有限元分析作为“以塑代钢”中一个非常重要的评估工具,约束其分析准确性的因素除了材料参数的定义、有限元分析模型的建立之外,还有有限单元网格的选择。对于壁厚不均匀的塑料离合踏板臂,使用Tetrahedron网格类型进行有限元分析,后处理时最大节点应力以及此网格单元的最大积分点应力也会有差异。结果显示,网格密度、积分点数量的变化对积分点应力的变化相对更小。

Nucleic acid nanoassembly-enhanced RNA therapeutics and diagnosis

RNAs are involved in the crucial processes of disease progression and have emerged as powerful therapeutic targets and diagnostic biomarkers.However,efficient delivery of therapeutic RNA to the targeted location and precise detection of RNA markers remains challenging.Recently,more and more attention has been paid to applying nucleic acid nanoassemblies in diagnosing and treating.Due to the flexibility and deformability of nucleic acids,the nanoassemblies could be fabricated with different shapes and structures.With hybridization,nucleic acid nanoassemblies,including DNA and RNA nanostructures,can be applied to enhance RNA therapeutics and diagnosis.This review briefly introduces the construction and properties of different nucleic acid nanoassemblies and their applications for RNA therapy and diagnosis and makes further prospects for their development.

Ionic Radius Dependent Kinetic Behavior for the Self-Assemblyand Chiral Amplification of Lanthanide Tetrahedral Cages

Comprehensive Summary Understanding the kinetic process during the self-assembly and chiral amplification of metal-organic polyhedra(MOPs)is critical for the rational preparation of chiral MOPs.Herein,we report the ionic radius dependent kinetic processes for the self-assembly and chiral amplification of Ln4L4-type(Ln,Lanthanides;L,ligand)lanthanide tetrahedral cages.The chiral Eu4(LR)4 tetrahedral cage is structurally characterized by nuclear magnetic resonance(NMR),electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS),and single crystal X-ray diffraction.Kinetic study on the stereo-controlled self-assembly of circularly polarized luminescence(CPL)-active Ln4(LR)4(Ln=LaIII,PrIII and EuIII)tetrahedra manifests that the larger ionic radius of Ln leads to faster assembly rates.Mixed-ligand cage assembly experiments with chiral LR/S,achiral Lac and Ln(1:3:4 molar ratio)reveal that the self-assembly and chiral amplification occur synchronously for the LaIII and PrIII cages,while two distinct steps,i.e.,first self-assembly and then chiral amplification,are observed for the EuIII cage.Such distinct kinetic behavior is attributed to different ligands exchange rates among the mixed-ligand Ln4L4 cages.This work provides fundamental guidance for fabrication and property-optimization of chiral lanthanide-based molecular materials.

BODIPY-based supramolecular fluorescent metallacages

During the past few years, the construction of BODIPY-based supramolecular fluorescent metallacages through coordination-driven self-assembly has gained increasing interest due to their unique photophysical properties and applications in catalysis, sensing, and bioimaging. In consideration of the rapid development of this field, it is time to summarize recent developments involving BODIPY-based metallacages.In this review, a comprehensive summary of the construction of BODIPY-based metallacages as well as their photophysical properties and applications will be presented.