Novel Gel—like Process for Synthesizing Submicron LiaNi0.8Co0.2O2 Powders Used in Lithium Ion Batteries

A novel gel-like process has been developed for synthesizing LiaNi0.8Co0.2O2 powders,using citric acid as a chelating agent. This process improves the homogeneity of constituent cation and enhances their reactivity in the obtained precursor. The results of electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. Its initial capacity reached 181.6 mAh/g and reversible efficiency at the first cycle is about 88.6%.     

在吡啶溶剂中氯化镍催化的溴代芳烃自身偶联反应

Pyridine was used as a solvent for homocoupling of aryl bromides catalyzed by nickel chloride/triarylphosphinein the presence of zinc and recycled easily.Triphenylphosphine was the best ligand for nickel in this coupling reac-tion.     

Tuning cell adhesion on gradient poly(2-hydroxyethyl methacrylate)-grafted surfaces

A simple yet versatile method was developed to prepare a low-density polymerization initiator gradient, which was combined with surface-initiated atom transfer radical polymerization (ATRP) to produce a well-defined poly(2-hydroxyethyl methacrylate) (HEMA) gradient substrate. A smooth variation in film thickness was measured across the gradient, ranging from 20 A to over 80 A, but we observed a nonmonotonic variation in water contact angle. Fits of X-ray reflectivity profiles suggested that at the low graft density end, the polymer chain structure was in a "mushroom" regime, while the polymer chains at high graft density were in a "brush" regime. It was found that the "mushroom" region of the gradient could be made adhesive to cells by adsorbing adhesion proteins, and cell adhesion could be tuned by controlling the density of the polymer grafts. Fibroblasts were seeded on gradients precoated with fibronectin to test cellular responses to this novel substrate, but it was found that cell adhesion did not follow the expected trend; instead, saturated cell adhesion and spreading was found at the low grafting density region.     

Universal and high-fidelity DNA single nucleotide polymorphism detection based on a CRISPR/Cas12a biochip

Single nucleotide polymorphisms (SNPs) are associated with many human diseases, so accurate and efficient SNP detection is of great significance for early diagnosis and clinical prognosis. This report proposes a universal and high-fidelity genotyping method in microfluidic point-of-care equipment based on the clustered regularly interspaced short palindromic repeat (CRISPR) system. Briefly, by systematically inserting the protospacer-adjacent-motif (PAM) sequence, we improved the universality of the CRISPR/Cas12a based SNP detection; by removing the complementary ssDNA and introducing an additional nucleotide mismatch, we improved the sensitivity and specificity. We preloaded the CRISPR/Cas12a reagents into the point-of-care biochip for automating the process, increasing the stability and long-term storage. This biochip enables us to rapidly and conveniently detect the genotypes within 20 min. In a practical application, the CRISPR/Cas12a biochip successfully distinguished three genotypes (homozygous wild type; the homozygous mutant type; and the heterozygous mutant type) of the CYP1A1*2 (A4889G, rs1048943), CYP2C19*2 (G681A, rs4244285), CYP2C9*3 (A1075C, rs1057910), and CYP2C19*3 (G636A, rs4986893) genes related to multiple cancers from 17 clinical blood samples. This CRISPR/Cas12a-based SNP genotyping method, being universal, accurate, and sensitive, will have broad applications in molecular diagnostics and clinical research.

A universal and high-fidelity genotyping method based on the clustered regularly interspaced short palindromic repeat (CRISPR) system was performed on the microfluidic point-of-care equipment.     

Synthesis, Structure, and Properties of a Model for Galactose Oxidase

An active-site analog of the radical copper enzyme galactose oxidase has been prepared from a synthetic tripod chelate ((2-pyridylmethyl)[(2-hydroxy-3,5-dimethylphenyl)methyl][(2-hydroxy-5-methyl-3-(methylthio)phenyl)methyl]amine, duncamine (dnc)) that binds a single Cu(II) ion through phenolate, thioether-substituted phenolate, and pyridylamine arms. The Cu complex crystallizes as a dinucleated dimer bridged by phenolate oxygens, and the structure has been determined by X-ray crystallography. Addition of pyridine (or other coordinating bases) dissociates the complex into a monomeric derivative that has been characterized spectroscopically (optical absorption and EPR) and electrochemically. The model provides insight into the properties of a mutant form of galactose oxidase which retains the same copper ligand complement as the wild type protein but lacks catalytic activity.     

Effect of Ce<Superscript>3+</Superscript> on spectral characteristic of D1/D2/Cytb559 complex from spinach

It was studied by spectroscopy that PSII reaction center complex consisting of three polypeptides, D₁, D₂ and Cytb559, were purified from PSII particle of CeCl₃ treated spinach. The results of the experiment show that Ce³⁺ could improve the growth of spinach, and accelerate electron transport of PSII particles. Of chl-a of UV-Vis spectrum of D1/D2/Cytb559 complex, Soret band was blue-shifted by 3 nm and Q band by 2 nm, respectively, and the fluorescence emission peak was blue-shifted by 5 nm in CeCl₃-treated spinach compared with the one in control. By the extended X-ray absorption fine structure (EXAFS) spectroscopy methods, it has been found that Ce³⁺ is coordinated with 8 nitrogen atoms in the first coordination shell with Ce-N bond length of 0.253 nm, and Ce³⁺ with 6 oxygen atoms in the second coordination shell with Ce-O bond length of 0.32 nm. However, the secondary structure of D1/D2/Cytb559 complex by circular dichroism (CD) spectroscopy has no significant change after CeCl₃ treated. It might be that Ce³⁺ binds to porphyrin rings of chlorophyll and oxygen of amino acid residue of polypeptide in D1/D2/Cytb559 complex, and then accelerates the primary reaction of PSII, intensifies function of P680⁺ primary electron donor of D1/D2/Cytb559, but there is little change in conformation of PSII reaction center complex.     

Multi-stage portfolio selection problem with dynamic stochastic dominance constraints

We study the multi-stage portfolio selection problem where the utility function of an investor is ambiguous. The ambiguity is characterized by dynamic stochastic dominance constraints, which are able to capture the dynamics of the random return sequence during the investment process. We propose a multi-stage dynamic stochastic dominance constrained portfolio selection model, and use a mixed normal distribution with time-varying weights and the K-means clustering technique to generate a scenario tree for the transformation of the proposed model. Based on the scenario tree representation, we derive two linear programming approximation problems, using the sampling approach or the duality theory, which provide an upper bound approximation and a lower bound approximation for the original nonconvex problem. The upper bound is asymptotically tight with infinitely many samples. Numerical results illustrate the practicality and efficiency of the proposed new model and solution techniques.

     

Global energy spectra of bands and density of states in a class of two-tile systems

Electronic properties of a general class of one-dimensional two-tile systems are calculated exactly. The systems containing periodic crystals, generalized Fibonacci quasicrystals, generalized Thue-Morse aperiodic lattices and even other two-tile aperiodic lattices, can be divided into two different families which are constructed by the inflation rules: {A, B}{A ^m11 B ^m12,A ^m21 B ^m22} and {A, B}{A ⁿ¹¹ B ⁿ¹²,B ⁿ²¹ A ⁿ²²}, respectively. As typical examples, global spectra of bands and density of states in some two-tile aperiodic systems are numerically calculated. Some interesting properties are obtained.     

Aspects of nucleon Compton scattering

We consider the spin-averaged nucleon forward Compton scattering amplitude in heavy baryon chiral perturbation theory including all terms to order . The chiral prediction for the spin-averaged forward Compton scattering amplitude is in good agreement with the data for photon energies110 MeV. We also evaluate the nucleon electric and magnetic Compton polarizabilities to this order and discuss the uncertainties of the various counter terms entering the chiral expansion of these quantities.     

Gas-discharge XeF* (B→X) laser with high specific output energy

The discharge characteristics of the XeF* (BX) laser are investigated. The NF₃ and Xe partial pressure of the laser gas mixture and the total gas pressure have been varied. A highest specific output energy of 4.7 J/l with an efficiency of 0.5% was obtained from a X-ray preionized Ne/Xe/NF₃ gas mixture at 6 bar with single-pulse excitation through a multichannel spark gap.