Large-scale synthesis of TiO2 nanorods via nonhydrolytic sol-gel ester elimination reaction and their application to photocatalytic inactivation of E. coli

A simple method of synthesizing a large quantity of TiO(2) nanorods was developed. A nonhydrolytic sol-gel reaction between titanium(IV) isopropoxide and oleic acid at 270 degrees C generated 3.4 nm (diameter) x 38 nm (length) sized TiO(2) nanocrystals. The transmission electron microscopic image showed that the particles have a uniform diameter distribution. X-ray diffraction and selected-area electron diffraction patterns combined with high-resolution transmission electron microscopic image showed that the TiO(2) nanorods are highly crystalline anatase crystal structure grown along the [001] direction. The diameters of the TiO(2) nanorods were controlled by adding 1-hexadecylamine to the reaction mixture as a cosurfactant. TiO(2) nanorods with average sizes of 2.7 nm x 28 nm, 2.2 nm x 32 nm, and 2.0 nm x 39 nm were obtained using 1, 5, and 10 mmol of 1-hexadecylamine, respectively. The optical absorption spectrum of the TiO(2) nanorods exhibited that the band gap of the nanorods was 3.33 eV at room temperature, which is 130 meV larger than that of bulk anatase (3.2 eV), demonstrating the quantum confinement effect. Oleic acid coordinated on the nanorod surface was removed by the reduction of the carboxyl group of oleic acid, and the Brunauer-Emmett-Teller surface area of the resulting naked TiO(2) nanorods was 198 m(2)/g. The naked TiO(2) nanorods exhibited higher photocatalytic activity than the P-25 photocatalyst for the photocatalytic inactivation of E. coli.     

Diterpenoids of Isodon macrophylla

Two new ent‐abietane diterpenoids, macrophynin E ( 1 ) and macrophynin F ( 2 ), and a known related ent‐abietanoid (?)‐lambertic acid ( 3 ), together with four known ent‐kauranoids, were isolated from the roots and aerial parts of Isodon macrophylla, respectively. The structures of the new compounds were elucidated on the basis of spectroscopic‐data analysis and chemical correlations.     

Determination of the cyclodextrin inclusion constant with the constant current coulometric titration method

With fluorometry this paper has proved that alpha-cyclodextrin (CD) and gamma-CD do not form inclusion complexes with procaine, while beta-CD and HP-beta-CD do. Their molar ratios are demonstrated both 1:1 with the equimolar variation method. The constant current coulometric titration method (CCCT) is first proposed and applied in the determination of the CD inclusion constant. To compare with this method, the fluorescence experiment has been done with the satisfactory results.     

A Selective Cholesterol Biosensor Based on Composite Film Modified Electrode for Amperometric Detection

An amperometric cholesterol biosensor based on immobilization of cholesterol oxidase in a Prussian blue (PB)/polypyrrole (PPy) composite film on the surface of a glassy carbon electrode was fabricated. Hydrogen peroxide produced by the enzymatic reaction was catalytically reduced on the PB film electrode at 0 V with a sensitivity of 39 μA (mol/L)^?1. Cholesterol in the concentration range of 10^?5 ? 10^?4 mol/L was determined with a detection limit of 6 × 10^?7 mol/L by amperometric method. Normal coexisting compounds in the bio‐samples such as ascorbic acid and uric acid do not interfere with the determination. The excellent properties of the sensor in sensitivity and selectivity are attributed to the PB/PPy layer modified on the sensor.     

Preparation and characterization of lithium ion-conducting glass-ceramics in the Li1 + xCrxGe2 − x(PO4)3 system

Li₂O–Cr₂O₃–GeO₂–P₂O₅ based glasses were synthesized by a conventional melt-quenching method and successfully converted into glass-ceramics through heat treatment. Experimental results of DTA, XRD, ac impedance techniques and FESEM indicated that Li_1.4Cr_0.4Ge_1.6(PO₄)₃ glass-ceramics treated at 900 °C for 12 h in the Li_1 + xCr_xGe_2 − x(PO₄)₃ (x = 0–0.8) system exhibited the best glass stability against crystallization and the highest ambient conductivity value of 6.81 × 10⁻⁴ S/cm with an activation energy as low as 26.9 kJ/mol. In addition, the Li_1.4Cr_0.4Ge_1.6(PO₄)₃ glass-ceramics displayed good chemical stability against lithium metal at room temperature. The good thermal and chemical stability, excellent conducting property, easy preparation and low cost make it promising to be used as solid-state electrolytes for all-solid-state lithium batteries.     

Electrochemical studies of the oxidation mechanism of polyamide on glassy carbon electrode

Polyamides containing N-methyl pyrroles and N-methyl imidazoles are a type of small molecule that can bind and recognize the bases of DNA with high affinity and specificity. Five polyamides were studied at glassy carbon electrode in acetate buffer by cyclic and differential pulse voltammetry to clarify their redox pathways. The polyamide electrochemical responses are compared by peak currents and peak potentials. The slopes of the three anodic E_p vs. pH plots of a typical polyamide are linear and show 0.059, 0.057, 0.056 V per pH in acid media, respectively, which correspond to a mechanism involving the equal number of electrons and protons. A possible mechanism for the redox pathway of various polyamides is proposed: the oxidation product of imidazole ring is acylamide and the results of in situ UV–Vis spectroscopy at Pt web electrode support the proposed mechanism. electrospray ionization mass spectroscopy (ESI-MS) indicates that one or two oxygen atoms are added into polyamide molecule after electrochemical oxidation.     

Deposition of spherical particles onto cylindrical solid surfaces. I. Numerical simulations

The permeability of fractal porous aggregates with realistic three-dimensional structure is investigated theoretically using model aggregates composed of identical spherical primary particles. Synthetic aggregates are generated by several techniques, including a lattice-based method, simulation of aggregation by differential settling and turbulent shear, and the specification of simple cubic structures, resulting in aggregates characterized by the number of primary particles, solid fraction, characteristic radius, and fractal dimension. Stokesian dynamics is used to determine the total hydrodynamic force on and the distribution of velocity within an aggregate exposed to a uniform flow. The aggregate permeability is calculated by comparing these values with the total force and velocity distribution calculated from the Brinkman equation applied locally and to the entire aggregate using permeability expressions from the literature. The relationship between the aggregate permeability and solid fraction is found to be best predicted by permeability expressions based on cylindrical rather than spherical geometrical elements, the latter tending to underestimate the aggregate permeability significantly. The permeability expressions of Jackson and James or Davies provide good estimates of the force on and flow through porous aggregates of known structure. These relationships are used to identify a number of general characteristics of fractal aggregates.     

ON THE RIEMANNIAN SPACES ADMITTING PARALLEL YANG-MILLS FIELDS

如果一个Yang-Mills场(规范群为任意李群)的场强的所有规范导数均为0,则称这个场为平行的Yang-Mills场.平行规范场是微分几何中对称空间的推广,它是Yang-Mills方程的特解. 本文的主要结果是下列两个定理： 定理1 容有非平凡的平行Yang-Mills场的四维黎曼空间必须是Kahler流形或半对称空间.这里半对称流形是满足 \[R_{ijkl}^ - = 0\](或\[R_{ijkl}^ + = 0\]) 的黎曼流形,其中\[R_{ijkl}^ \pm \]分别是曲率张量的自对偶部份及反自对偶部份,而":"表示共变 导数. 定理2 半对称空间如果不是对称空向,则必为Kahler-Einstein空间或共形半平坦Einstein空间.这里共形半平坦是指Weyl张量的反自对偶部份或自对偶部份为0.在附录中作者给出了二维黎曼流形上Yang-Mills方程的所有的整体解.     

Oxidatively truncated docosahexaenoate phospholipids: total synthesis,generation, and Peptide adduction chemistry

The recent immunological detection of extraordinarily high levels of carboxyethylpyrrole (CEP) modifications of proteins from the retinas of individuals with age-related macular degeneration provided presumptive evidence for the involvement of docosahexaenoate-derived oxidatively truncated phospholipids in retinal pathology. To facilitate the in vivo detection and characterization of the chemistry and biological activities of these postulated naturally occurring molecules, a family of oxidatively truncated phospholipids was prepared by total syntheses. Their formation in oxidation reactions of a docosahexaenoate ester of 2-lysophosphatidylcholine (DHA-PC) was also demonstrated. Free radical-induced oxidative cleavage of DHA-PC promoted by myeloperoxidase or copper ions generates similar mixtures of these phospholipids. The most abundant products were 1-palmitoyl-2-succinoyl-sn-glycero-3-phosphatidylcholine (4.7%) and 2-(6-carboxy-4-oxohex-5-enoyl)-1-palmitoyl-sn-glycero-3-phosphatidylcholine (1.7%). Both of these oxidatively truncated phospholipids are homologues of biologically active arachidonate-derived phospholipids. A minor product from DHA-PC, 2-(4-hydroxy-7-oxohept-5-enoyl)-1-palmitoyl-sn-glycero-3-phosphatidylcholine (0.4% yield), reacted with the epsilon-amino group of a peptide lysyl residue to produce a CEP derivative in 0.7% yield. These observations support the previous conclusion, based on immunological evidence, that CEPs are generated by the reaction of an oxidatively truncated phospholipid with proteins in the retina and further indicate that CEP protein modifications probably represent only a tiny fraction of the products generated upon oxidative damage of DHA-PC in photoreceptor disk membranes.     

Two-photon excitation studies of hypocrellins for photodynamic therapy

The photophysical and photochemical properties of hypocrellins (HA and HB) are examined with two-photon excitations at 800 nm using femtosecond pulses from a Ti:sapphire laser. The two-photon excited fluorescence spectra of HA and HB are very similar to those obtained by one-photon excitation, which may indicate that the two-photon induced photodynamic processes of hypocrellins are similar to one-photon induced photodynamic processes. The two-photon excitation cross sections of HA and HB are measured at 800 nm as about 34.8 x 10(-50) cm(4) s/photon and 21.3 x 10(-50) cm(4) s/photon, respectively. The large two-photon cross sections of both HA and HB, suggest that the hypocrellins can be potential two-photon phototherapeutic agents. As an example for two-photon photodynamic therapy of hypocrellins, we also further examine the cell-damaging effects of HA upon two-photon illumination. Our preliminary results of cell viability test indicate hypocrellins can effectively damage the Hela cells under two-photon illumination.