矩形截面毛细管电泳和二维分离

在石英单晶表面制成矩矩截面毛细管柱中进行电泳实验。由于矩形柱比圆形柱有更大散热侧面积且石英单晶的导热性能远无于熔融石英，所以可施加较高的场强，不仅提高了柱效，而且缩矩了分离时间。两相交的通道之间形成自然连接，可实现二维分离，并消除死体积。     

Photochemically Induced Solid-State Degradation, Condensation, and Rearrangement Reactions in Lignin Model Compounds and Milled Wood Lignin

Abstract— Milled wood lignin produced from alkaline hydrogen peroxide-bleached softwood thermomechanical pulp (TMP) fibers was adsorbed on pure cellulose and irradiated for variable periods of time under oxygen and/or nitrogen. The absolute amounts of β-O-4 ethers, phenolic hydroxyl groups, carboxylic acids and various condensed phenolic units were quantified, nondestructively, using ³¹P NMR spectroscopy. Photoirradiation was found to severely cleave the β-O-4 ethers present in lignin with the concomitant formation of new phenolic units. The rate of this cleavage was found to be faster under oxygen than under nitrogen. The catalytic role of oxygen can be rationalized by invoking the formation of peroxy free radicals that may initiate new sites of radical generation ( e.g. ketyl radicals) within the lignin causing the subsequent breakdown of the β-O-4 linkage. The photoirradiation was found to cause a net increase of the C₅-related condensed phenolic units in lignin. Among these, C_α-C₅ and/ or C_β-C₅ phenolic moieties were found to predominate. Similar irradiation of a binary mixture of model compounds resembling structures present in softwood lignin resulted in 18 products that were identified and quantified using gas chromatography coupled to mass spectrometry. The photochemical products obtained supported the phenacyl and ketyl mechanistic pathways to pho-toyellowing, whereas the detection of β-5 coupling products (common in both the model compound and milled wood lignin studies) may point a new avenue toward the formation of light-induced products that has not been previously considered in the solid state.     

Preparation of 2-pyridone-containing tricyclic alkaloid derivatives as potential inhibitors of tumor cell proliferation by regioselective intramolecular N- and C-acylation of 2-pyridone

A novel and practical preparation of 2-pyridone-containing tricyclic alkaloid derivatives was developed. By regioselective intramolecular N- and C-acylation of 2-(4-aryl-2-pyridon-6-yl)benzoic acid, a pair of structural isomers 2-aryl pyrido[2,1-a]isoindole-4,6-diones and 4-aryl 1-methyl-1H-indeno[1,2-b]-pyridine-2,5-diones, as potential inhibitors of tumor cell proliferation, were prepared respectively.     

Lyotropic liquid crystalline poly(aryl ether ketone) copolymer containing phthalazinone moiety and biphenyl mesogen

A novel lyotropic liquid crystalline material poly(aryl ether ketone) copolymer containing phthalazinone moiety and biphenyl mesogen named P-8515 was developed by a mild solution polycondensation method. The molecular weight (M_n) was 53,000 and the value of molecular weight distribution index (MDI) was 2.49 detected by GPC. The critical concentration (C^∗) of P-8515 was 36 wt% and P-8515 exhibited characteristic nematic lyotropic liquid crystalline phases in NMP solution at different concentrations and the phase morphology changed to a typical threaded texture when shear forces were induced from PLM observations. The T_g value was 238 °C and the value for 5% weight loss temperature was 515 °C in nitrogen from DSC and TGA determinations, respectively.     

Versatile cobalt complexes for initiating immortal ring‐opening polymerization (ROP) of lactide (LA), mediating living radical polymerization of t‐butyl acrylate (tBA) and catalyzing copolymerization of LA and tBA by combination of ROP and organometallic‐mediated radical polymerization

Low‐cost, highly active and versatile amino‐bis(phenolate) cobalt complexes are developed. The cobalt complexes can control living polymerization of different categories of monomers including lactide (LA) by immortal ring‐opening polymerization in argon and even in air and acrylate via living radical polymerization (LRP). The cobalt‐based catalysts were used for copolymerization of LA and acrylate. The immortal polymerization of LA using the cobalt complexes as initiators proceeds in argon and even in air and without the requirement for extensive drying techniques or inert atmosphere whilst retaining end‐group fidelity. The cobalt complexes are used to mediate LRP of t‐butyl acrylate (tBA) in methanol. The block copolymerization of LA and tBA catalyzed by single‐site cobalt organometallic catalyst is also reported for the first time. This cobalt system offers a versatile and green way to produce homopolymers and block copolymers.     

Chaotic Dynamics of a Josephson Junction with a Ratchet Potential and Current-Modulating Damping

The chaotic dynamics of a Josephson junction with a ratchet potential and current-modulating damping are studied. Under the first-order approximation, we construct the general solution of the first-order equation whose boundedness condition contains the famous Melnikov chaotic criterion. Based on the general solution, the incomputability and unpredictability of the system’s chaotic behavior are discussed. For the case beyond perturbation conditions, the evolution of stroboscopic Poincaré sections shows that the system undergoes a quasi-periodic transition to chaos with an increasing intensity of the rf-current. Through a suitable feedback controlling strategy, the chaos can be effectively suppressed and the intensity of the controller can vary in a large range. It is also found that the current between the two separated superconductors increases monotonously in some specific parameter spaces.     

Rate dependence of temperature fields and energy dissipations in non-static pseudoelasticity

The temperature fields and the energy dissipations of shape memory alloys during the stress-induced martensitic transformations are studied theoretically and experimentally. The effect of the loading rate is analyzed. It was found that the temperature field inside a shape memory alloy sample varies strongly in space and time. The increase rate of the temperature is given by the difference between the rate of the latent heat release and the rate of the heat convection and conduction. The notion and the rate dependence of the energy dissipation are discussed in connection with the stress–strain hysteresis, the entropy production, and the Clausius–Duhem inequality.     

Depressing defocusing effect in microscopy by bi-orthogonal wavelet transform

For different dimensions, heights and irregular shapes, small and large particles cannot be viewed simultaneously as sharp images under the microscope due to optical defocusing effects. Bi-orthogonal wavelet transform is used in this paper to depress such defocusing effect by merging the wavelet coefficients of the image series. The algorithm is presented in detail, using SWE(13,7) and CDF(2,2), and a few particle images are provided to validate the proposed method.