An improved Pfitzinger reaction: Eco-efficient synthesis of quinaldine-4-carboxylates by TMSCl-mediated

We report herein an improved Pfitzinger reaction for the synthesis of highly functionalized quinaldines from 1,3-dicarbonyl compounds, isatins and alcohols mediated by TMSCl. This synthesis involves cyclization and esterification in one-step cascade process for the formation of a carboxylate (CO₂R) at the 4-position of quinaldine ring. Moreover, this procedure shows highly efficient, good functional group tolerance, operational simplicity, environment-friendly and feasibility of scale up.     

Biochemical sensor based on a novel all-fibre cavity ring down spectroscopy technique incorporating a tilted fibre Bragg grating

A novel all-fibre cavity ring down spectroscopy technique is proposed where a tilt fibre Bragg grating (TFBG) or long-period grating (LPG) in the cavity provides sensitivity to surrounding medium. Such configuration with an LPG as the representative was theoretically analyzed. Two spectral bands were identified employable for sensing of surrounding refractive index for a weak LPG while only one band existed for a strong LPG. A TFBG, with enhanced sensitivity compared to usual LPGs, was used in a ring down cavity of 1 m constructed with 2 fibre Bragg gratings as the reflectors and the decay time changed from 220 to 450 ns when the TFBG was immersed into water from air.     

The introduction of antibacterial drug pipemidic acid into the POM field: Syntheses, characterization and antitumor activity

Two new compounds based on polyoxometalates (POMs) and the quinolone antibacterial drug pipemidic acid (HPPA), {[Ni(PPA)₂]H₄[SiW₁₂O₄₀]}·HPPA·3H₂O (1), and {[Zn(PPA)₂]₂H₄[SiW₁₂O₄₀]}·3H₂O (2), have been synthesized under hydrothermal conditions and structurally characterized by routine technique. Single-crystal X-Ray diffraction analysis shows that compound 1 is constructed by Keggin clusters grafted by binuclear nickel clusters, isolated HPPA and water molecules, while compound 2 consists of Keggin clusters grafted by binuclear zinc clusters and water molecules. Due to the selection of different transition metal (TM) ions, compounds 1 and 2 exhibit different structures and antitumor activities. Compound 1 possesses 0D structure and shows no antitumor activities. However, compound 2 possesses 1D structure and exhibits higher antitumor activities than its parent compound. The results show that introduction of different TM-PPA moieties onto the polyoxoanion surface can affect not only the final structures but also their antitumor activities.     

On general sum-connectivity index

We report some properties of the reverse degree distance of a connected (molecular) graph, and, in particular, its relationship with the first Zagreb index and Wiener index. We also show that the reverse degree distance satisfies the basic requirement for a branching index.     

The Empirical Bayes Estimation of the Location Parameter in Double-Exponential Family under the LINEX Loss Function

In this paper, we derive the Bayes estimator of the location parameter in double-exponential family under the LINEX loss function, and then construct the corresponding empirical Bayes estimator. It is shown that the empirical Bayes estimator is asymptotically optimal with convergence rate being , , where 1/2相似文献   

熵极小动力系统的复杂性

设X是一个紧致度量空间,f:X→X是一个连续映射,(X,f)是熵极小的.该文首先证明了f是强遍历的;另外,如果还假设X中存在f的一个真的(拟)弱几乎周期点,则得到f具有正拓扑熵且对任意的n1,f~n是遍历敏感依赖的.因此,f在Li-Yorke和Takens-Ruelle意义下是混沌的.该文所得结论改进和推广了最近的一些结论.     

Fermionic-mode entanglement in non-Markovian environment

We evaluate the non-Markovian effects on the entanglement dynamics of a fermionic system interacting with two dissipative vacuum reservoirs. The exact solution of density matrix is derived by utilizing the Feynman–Vernon influence functional theory in the fermionic coherent state representation and the Grassmann calculus, which are valid for both the fermionic and bosonic baths, and their difference lies in the dependence of the parity of the initial states. The fermionic entanglement dynamics is presented by adding an additional restriction to the density matrix known as the superselection rules. Our analysis shows that the usual decoherence suppression schemes implemented in qubits systems can also be achieved for systems of identical fermions, and the initial state proves its importance in the evolution of fermionic entanglement. Our results provide a potential way to decoherence controlling of identical fermions.