Three-component reactions of isochromenylium tetrafluoroborates via non-classical [4+2]-intermediates: mild one-step metal-free synthesis of functionalized dihydronaphthalenes and tetrahydronaphthalenes

Two novel types of elegant three-component reactions of stable isochromenylium tetrafluoroborates (ICTBs) have been developed under mild metal-free conditions in this work. Mechanistically, these reactions are commonly initiated by a [4+2]-cycloaddition between the non-classical isochromenylium diene and the aldehyde-enol, and terminated by the following addition of weak nucleophiles, including nitriles or the second equivalent of aldehydes, in a one-pot fashion. The developed methodologies exhibit excellent chemoselectivity, regioselectivity, and diastereoselectivity, and provide a new convenient access to functionalized dihydronaphthalenes and tetrahydronaphthalenes.     

Exploring antibiotic resistant mechanism by microcalorimetry

In an effort to probe the reaction of antibiotic hydrolysis catalyzed by B3 metallo-??-lactamase (M??L), the thermodynamic parameters of penicillin G hydrolysis catalyzed by M??L L1 from Stenotrophomonas maltophilia were determined by microcalorimetric method. The values of activation free energy ??G _?? ^?? are 88.26, 89.44, 90.49, and 91.57?kJ?mol^?1 at 293.15, 298.15, 303.15, and 308.15?K, respectively, activation enthalpy ??H _?? ^?? is 24.02?kJ?mol^?1, activation entropy ??S _?? ^?? is ?219.2511?J?mol^?1?K^?1, apparent activation energy E is 26.5183?kJ?mol^?1, and the reaction order is 1.0. The thermodynamic parameters reveal that the penicillin G hydrolysis catalyzed by M??L L1 is an exothermic and spontaneous reaction.     

Two wheel-like polytungstates obtained by incorporation of two {Cu(4)} clusters and two molybdenum centers in the {W(48)} wheel

Two new {P(8)W(48)} wheel-based compounds, Na(12)Li(16){[Cu(H(2)O)](2)[Cu(4)(OH)(4)(H(2)O)(8)](2)P(8)W(48)O(184)}·55H(2)O (1), and K(4)Na(24)Li(10){(MoO(2))(2)(P(8)W(48)O(184))}·61H(2)O (2) have been synthesized by a conventional aqueous solution method, and characterized by UV, IR, TG analysis, XPRD, (31)P NMR, XPS, single-crystal X-ray diffraction analyses, magnetic study and electrochemistry study. In compound 1, a wheel-type {P(8)W(48)} containing two {Cu(4)} clusters and two isolated Cu cations results in a 10-Cu-containing polyoxotungstate, which represents the first {P(8)W(48)}-based compound trapping two transition metal (TM) clusters in its inner cavity. Further, the polyoxoanion was connected by Na(+) and Li(+) cations into a 3D framework. Compound 2 is a 2-Mo-containing {P(8)W(48)}-based polyoxotungstate. Magnetic study indicates that antiferromagnetic interactions exist in compound 1.     

Complex dynamics in a discrete-time predator-prey system without Allee effect

In this paper, complex dynamics of the discrete-time predator-prey system without Allee effect are investigated in detail. Conditions of the existence for flip bifurcation and Hopf bifurcation are derived by using center manifold theorem and bifurcation theory and checked up by numerical simulations. Chaos, in the sense of Marotto, is also proved by both analytical and numerical methods. Numerical simulations included bifurcation diagrams, Lyapunov exponents, phase portraits, fractal dimensions display new and richer dynamics behaviors. More specifically, this paper presents the finding of period-one orbit, period-three orbits, and chaos in the sense of Marotto, complete period-doubling bifurcation and invariant circle leading to chaos with a great abundance period-windows, simultaneous occurrance of two different routes (invariant circle and inverse period- doubling bifurcation, and period-doubling bifurcation and inverse period-doubling bifurcation) to chaos for a given bifurcation parameter, period doubling bifurcation with period-three orbits to chaos, suddenly appearing or disappearing chaos, different kind of interior crisis, nice chaotic attractors, coexisting (2,3,4) chaotic sets, non-attracting chaotic set, and so on, in the discrete-time predator-prey system. Combining the existing results in the current literature with the new results reported in this paper, a more complete understanding is given of the discrete-time predator-prey systems with Allee effect and without Allee effect.     

A result on certain coset subalgebras of the βγ-system

In this paper, for the highest weight module V4 of sl(2,C) with the highest weight 4, we describe subalgebras Sβ(V4)θ+ and Sγ(V4)θ+ of the βγ-system coset S(V4)θ+ by giving their generators. These coset subalgebras are interesting, new examples of strongly finitely generated vertex algebra.     

流动注射后化学发光法测定阿米卡星

过氧化单硫酸盐具有很强的氧化性,本实验发现,在pH=11.5的条件下,过氧化单硫酸盐(PMS)可以氧化鲁米诺(Luminol)产生瞬时化学发光,发光结束后注入阿米卡星又会出现很强的慢速后化学发光.结合流动注射的方法,利用此体系建立了流动注射后化学发光测定阿米卡星的新方法,并对其后化学发光反应的动力学性质、化学发光光谱进行了研究,讨论了可能的反应机理.阿米卡星浓度在4.0×10-5～8.0×10-2 g/L范围内与发光强度呈良好的线性关系,检出限(3σ)为1×10-5 g/L,相对标准偏差为2.9%.本方法具有选择性好、操作简单、分析速度快和重复性好等优点,已成功用于尿液中阿米卡星含量的测定,结果令人满意.     

W-State Generation and Manipulation for Ion-Trap-Based Quantum-Information Processing

We propose an ion-trap scheme for one-step generation of a special configuration of W-class state which has recently been shown to be better than canonical W states for several quantum-information processing tasks. We also present a method for one-step realization of a nontrivial collective operation which can transform a canonical W state into a fully separable state. Such a transformation plays a key role in recently proposed quantum protocols. The operation speed in our schemes increases with the number of qubits. This is contrary to usual entanglement generation and quantum manipulation schemes which take more and more time with the increase of the number of qubits.     

一种新的流动注射电化学发光分析方法及硫离子的分析测定研究

设计了一种用于流通体系的电解池,并以恒电流电解法与流动注射技术相结合,在线定量电解产生不稳定试剂次溴酸根,使其浓度和反应活性得以在线控制,稳定地应用于化学发光分析.在此基础上,研究了BrO^-在pH=9.60Na₂CO₃-NaHCO₃缓冲介质中氧化鲁米诺弱化学发光反应的分析特性,并基于硫离子对该弱化学发光反应体系的发光强度的增敏作用,建立了一种新的测定S^2-的流动注射电化学发光分析法.采用该方法测定S^2-的线性范围为3.10×10^-7～9.30×10^-5mol/L,检出限为1.00×10^-7mol/L,相对标准偏差为2%[n=11,c(S^2-)=3.10×10^-6mol/L]     

流动注射光纤荧光探针动力学法测定铁的研究

研究了8-苯胺基-1-萘磺酸作为表面活性剂胶束荧光探针的性质,并将其用作动力学分析的荧光指示剂。建立了以铁(Ⅲ)催化过氧化氢氧化ANS-Brij35体系荧光猝灭反应为基础,用流动注射和光导纤维技术测定痕量铁的动力学分析新方法。该法线性范围为5～300ng/mL,检测下限为2ng/mL,绝对检出量为0.2ng,对20ng/mL铁(Ⅲ)进行11次测定相对标准偏差为0.27%,可直接用于人发、纯铝和铝合金中铁的测定。     

Preparation of enantiomerically pure 2-(1′-aminomethyl)furan derivatives and synthesis of an unnatural polyhydroxylated piperidine

Zinc-mediated propargylation of α-acylaminoaldehydes, and subsequent oxidative isomerization followed by Ag(I)-catalyzed cycloisomerization conveniently provides a new enantioselective route to the corresponding 2-aminoalkylfurans. One of these furans was successfully converted into an unnatural polyhydroxylated piperidine that efficiently incorporated structural features of the starting material. This represents a new entrance to biologically interesting polyhydroxylated piperidines having diverse substitutions.