Coatings of one monomer molecularly imprinted polymers for open tubular capillary electrochromatography

One monomer molecularly imprinted polymer coatings were first synthesized in fused silica capillary columns with 2-methacrylamidopropyl methacrylate (MAM) as single functional monomer in addition to a cross-linking monomer. Since MAM may generate no or little EOF, a strategy of precursor of polymerization, which does not interfere with the formation of defined imprints, was used to introduce an ionizable functional monomer to generate a stable electroosmotic flow for electrochromatography (CEC) by post-polymerization hydrolization. The resulting MAM-based open-tubular imprinted capillary was able to separate enantiomers by means of CEC. The resolution of enantiomers separation achieved on S-amlodipine-imprinted capillary was up to 16.1. The strong recognition ability (selectivity factor was 3.23) and high column performance (theory plates was 26,053 plates m(-1)) of template were obtained. The MIP coatings were also prepared using either S-naproxen or S-ketoprofen as template molecule. The resolutions of enantiomers separation were 2.20 and 4.56, respectively. The results illustrate that the synthesis of MIP using one monomer is not only an experimental-simplified process, but also an approach to producing chiral stationary phase with high efficiency and selectivity.     

A mild liquid reduction route toward uniform blue-emitting EuCl2 nanoprisms and nanorods

In this work, for the first time, uniform blue-emitting EuCl(2) nanoprisms and nanorods were synthesized from Eu(CCl(3)COO)(3)·2H(2)O [or Eu(CH(3)COO)(3)·H(2)O] by a novel mild liquid reduction route, using acetamidine hydrochloride (or picolinamidine hydrochloride) as the reductant in oleylamine. The synthetic reaction even can take place under an atmosphere in the absence of inert gas at around 300 °C. The EuCl(2) nanoprism dispersion in n-hexane showed an intense blue emission when excited by UV light.     

Mapping molecular conformations with multiple-mode two-dimensional infrared spectroscopy

The multiple-mode two-dimensional infrared (2D-IR) spectrum in a broad frequency range from 1000 to 3200 cm(-1) of a 1-cyanovinyl acetate solution in CCl(4) is reported. By analyzing its relative orientations of the transition dipole moments of normal modes that cover vibrations of all chemical bonds, the three-dimensional molecular conformations and their population distributions of 1-cyanovinyl acetate are obtained, with the aid of quantum chemistry calculations that translate the experimental transition dipole moment cross angles into the cross angles among chemical bonds.     

Synthesis, structures and luminescent properties of Co(II) and Ni(II) metal-organic frameworks with semirigid diphthalic ligands

A series of transition metal coordination polymers [Co(H₃L)₂(4,4′- bpy)(H₂O)₂]_n?n(4,4′-bpy) (1), [Ni(H₂L)(4,4′-bpy)(H₂O)₂]_n (2), [Co₂(L)(phen)₂(H₂O)₄]_n?(H₂O)_2n (3), and [Ni₂(L)(phen)₂(H₂O)₄]_n?(H₂O)_2n (4) have been assembled from a semirigid multicarboxylate ligand 3,3′-(1,4-phenylenebis(oxy))diphthalic acid (H₄L) with the help of 4,4′-bipyridine (4,4′-bpy) ligand or 1,10-phenanthroline (phen) ligand. X-ray single crystal diffraction analysis reveals that complex 1 crystallizes in the space group of P − 1 and displays a one-dimensional (1D) chain structure constructed from 4,4′-bpy ligand and H₃L ligand, which was further interlinked to form a three-dimensional network via hydrogen bonds. In complex 2, Ni(II) atoms are coordinated by L ligand in monodentate fashion to form alternate left- and right-helices, which are further bridged together by the coordination interactions between Ni(II) atoms and 4,4′-bpy, leading to a 2-fold (4, 4)-connected interpenetrating network. Isostructural complexes 3 and 4 belong to the space group P − 1 and display a 1D chain structure constructed from phen and L ligands, which was further interlinked to form a 2D plane via π–π interactions. In addition, their thermal and luminescent properties were also investigated.     

Recognizing ortho-, meta- or para-positional isomers of S-methyl methoxylphenylmethylenehydrazine dithiocarboxylates by ESI-MS2: The positional effect of the methoxyl substituent

The dissociation chemistry of the ortho-, meta- or para-isomers of protonated S-methyl methoxyl- (or chloro-) benzenylmethylenehydrazine dithiocarboxylate, RPhCHN–NHC(S)–SCH₃ (R = MeO– or Cl–), has been investigated by collision induced dissociation experiments and DFT theoretical calculations. The three methoxyl-substituted isomers were easily differentiated according to the different abundance of the characteristic ion at m/z 136, resulting from the varying reactivity of the (NSC)SCH₃ elimination. This fragmentation is triggered by the positive charge upon protonation on the imine N2. Relative to the meta isomer, the positive charge on N2 in the para isomer is dispersed due to the electron donating resonance of the methoxyl group, which leads to higher energy barrier in the dissociation reaction and the less abundant product ion (m/z 136) in the MS/MS. (NSC)SCH₃ elimination of the ortho- isomer is further suppressed due to both the resonance effect and the “ortho effect” (an intramolecular hydrogen bond), with much higher energy barrier and extremely lower abundance of the fragment ion (m/z 136, 0.4%). The chloro substituted isomers, however, are short of the above positional effects due to the weak electronic effect of the substituent, and share the similar tandem mass spectrum.     

Physicochemical properties, in vitro antioxidant activities and inhibitory potential against α-glucosidase of polysaccharides from Ampelopsis grossedentata leaves and stems

In the present study, polysaccharides named ALPS and ASPS were isolated from Ampelopsis grossedentata leaves and stems, respectively. Physicochemical properties, in vitro antioxidant activities and the inhibitory effects on α-glucosidase of ALPS and ASPS were investigated. It was found that both ALPS and ASPS were acid protein-bound heteropolysaccharides, although with considerably different chemical composition and molecular weight distribution. Meanwhile, in comparison with ALPS, ASPS exhibited stronger antioxidant activity and inhibitory potential against α-glucosidase according to the in vitro evaluation. Moreover, our results suggested that protein and uronic acid might, at least partly, contribute positively to the biological behavior of ALPS and ASPS.     

Robust partially mode‐dependent H∞ filtering for discrete‐time nonhomogeneous Markovian jump neural networks with additive gain perturbations

This paper studies the robust partially mode‐dependent H_∞ filtering for nonhomogeneous Markovian jump neural networks with additive gain perturbations. The discrete time‐varying jump transition probability matrix is considered to be a polytope set. A partially mode‐dependent filter with additive gain perturbations is constructed to increase the robustness of the filter, which is subjects to H_∞ performance index. Based on the Lyapunov function approach, sufficient conditions are established such that the filtering error system is robustly stochastically stable. The efficiency of the new technique is illustrated by an illustrative example and a biological network example.     

Möbius transformation and a version of Schwarz lemma in octonionic analysis

The octonion is a generalization of complex to noncommutative and nonassociative space which has closed relation with exception geometries, wave equation, Yang‐Mills equations, black hole, string theory, and special relativity. In this paper, the Möbius transformation in this manner is first introduced, and some properties are discussed about the transformation in octonionic analysis. Some technique lemmas will be given to solve the problems caused by the weak form of associativity. These versions of Schwarz lemma and Schwarz‐Pick lemma are first studied in octonionic setting which will invoke integral representation formula for harmonic function and Möbius transformations. This will generalize the corresponding results which appear in the classical function theory to nonassociative space and may give new energy for the development of physics.     

2013年声频工程学术论坛暨学术交流年会在广州召开

中国电子学会声频工程分会和中国声学学会声频工程分会于2013年9月23日至9月26日,在广州举办了《2013年声频工程学术论坛暨学术交流年会》。     

Probing the hydroxyl radical-mediated reactivity of peroxynitrite by a spin-labeling fluorophore.

The decomposition of peroxynitrite at physiological pH yielded a hydroxyl radical, which reacted rapidly with dimethyl sulfoxide (DMSO) to produce a methyl radical (*CH3), which was then trapped by a spin-label fluorophore nitroxide-linked naphthalene (NTEMPO), a carbon-centered radical probe with a low fluorescence intensity, and transformed to a stable diamagnetic O-alkoxyamine, a high-fluorescence compound. The fluorescence increment was proportional to the concentration of the hydroxyl radical, and then to the concentration of peroxynitrite. NTEMPO therefore was demonstrated to be capable of detecting hydroxyl radicals generated from peroxynitrite, and the method was proved to be simple and sensitive. The hydroxyl radical-mediated reactivities of peroxynitrite to several amino acids, such as tyrosine, phenylalanine and histidine, were then evaluated by the spin-labeling fluorophore NTEMPO at pH 7.4 and, 37 degrees C. The obtained data were in good agreement with the reference values, respectively.