微波辅助溶剂热合成In-Si共改性TiO2的增强光催化性能

利用微波辅助溶剂热法合成了In-Si 共改性的TiO₂ 光催化剂. 粉末X 射线衍射（XRD）、激光拉曼（Raman）光谱、N₂吸脱附（BET）、X射线光电子能谱（XPS）、光致发光（PL）光谱和紫外-可见漫反射光谱（UV-VisDRS）等实验表明,尽管掺杂和改性后TiO₂结晶度略有降低,但不影响光催化剂锐钛相的形成. Si 掺杂入TiO₂晶格使颗粒变小,比表面积变大. In 不能进入TiO₂晶格,在TiO₂表面形成了In₂O₃. 罗丹明B（RhB）降解实验显示,In-Si 共改性TiO₂表现出很高的紫外和可见光催化活性,Si：In：Ti 的摩尔比为0.03：0.02：1 的样品（IST-2）光催化活性最高,紫外光下3 min 即可将RhB降解完全,可见光下120 min RhB降解率为97%,这是由材料的高表面积,In₂O₃-TiO₂复合半导体之间高效电荷转移及染料敏化等共同作用所致. 对于苯酚,光催化降解则相对缓慢,700 min内尚不能降解完全.     

Triterpenoids from Rhaponticum Uniflorum

The isolation and identification of twenty‐one components (including four new triterpenoid saponins and one new triterpenoid acid) from the root of Rhaponticum uniflorum (L.) DC. (Compositae) are described. Their structures were determined on the basis of spectral analysis and chemical trans formation. The new compounds were identified as 3‐O‐α‐L‐arabinopyranosyl‐urs‐12,18(19)‐dien‐28‐oic acid β‐D‐glucopyranosyl ester, 3β‐ hydroxyurs‐12,18(19)‐dien‐28‐oic acid β‐D‐glucopyranosyl ester, 3β‐hydroxyurs‐12,19(29)‐dien‐28‐oic acid β‐D‐glucopyranosylester, 3‐O‐α‐L‐arabinopyranosyl‐urs‐9(11),12‐dien‐28‐oic acid β‐D‐glucopyranosyl ester and 2 α,3 α, 19α,25‐tetrahydroxyurs‐12‐en‐23,28‐dioic acid.     

Photoinduced intramolecular electron transfer and triplet energy transfer in a steroid-linked norbornadiene-carbazole dyad

Bichromophoric compound 3 beta-((2-(methoxycarbonyl)bicyclo[2.2.1]hepta-2,5-diene-3-yl)carboxy)androst-5-en-17 beta-yl-[2-(N-carbazolyl)acetate] (NBD-S-CZ) was synthesized and its photochemistry was examined by fluorescence quenching, flash photolysis, and chemically induced dynamic nuclear polarization (CIDNP) methods. Fluorescence quenching measurements show that intramolecular electron transfer from the singlet excited state of the carbazole to the norbornadiene group in NBD-S-CZ occurs with an efficiency (Phi SET) of about 14 % and rate constant (kSET) of about 1.6 x 10(7) s-1. Phosphorescence and flash photolysis studies reveal that intramolecular triplet energy transfer and electron transfer from the triplet carbazole to the norbornadiene group proceed with an efficiency (TET + TT) of about 52 % and rate constant (kTET + kTT) of about 3.3 x 10(5) s-1. Upon selective excitation of the carbazole chromophore, nuclear polarization is detected for protons of the norbornadiene group (emission) and its quadricyclane isomer (enhanced absorption); this suggests that the isomerization of the norbornadiene group to the quadricyclane proceeds by a radical-ion pair recombination mechanism in addition to intramolecular triplet sensitization. The long-distance intramolecular triplet energy transfer and electron transfers starting both from the singlet and triplet excited states are proposed to proceed by a through-bond mechanism.     

High levels of soluble herpes virus entry mediator in sera of patients with allergic and autoimmune diseases

Herpes virus entry mediator (HVEM) is a newly discovered member of the tumor necrosis factor receptor (TNFR) superfamily that has a role in herpes simplex virus entry, in T cell activation and in tumor immunity. We generated mAb against HVEM and detected soluble HVEM (SHVEM) in the sera of patients with various autoimmune diseases. HVEM was constitutively expressed on CD4(+) and CD8(+) T cells, CD19(+) B cells, CD14(+) monocytes, neutrophils and dendritic cells. In three-way MLR, mAb 122 and 139 were agonists and mAb 108 had blocking activity. An ELISA was developed to detect sHVEM in patient sera. sHVEM levels were elevated in sera of patients with allergic asthma, atopic dermatitis and rheumatoid arthritis. The mAbs discussed here may be useful for studies of the role of HVEM in immune responses. Detection of soluble HVEM might have diagnostic and prognostic value in certain immunological disorders.     

Near-infrared fluorimetric determination of nucleic acids by shifting the ion-association equilibrium between heptamethylene cyanine and Alcian blue 8GX

A new method based on near-infrared (near-IR) fluorescence recovery, employing a two-reagent system which is composed of an anionic heptamethylene cyanine (HMC) and a polycationic phthalocyanine dye, Alcian blue 8GX, is presented for the determination of nucleic acids. With a maximum excitation wavelength at 766 nm and a maximum emission wavelength at 796 nm, the fluorescence recovery is linear with the concentration of nucleic acids added. Factors including the acidity of the medium, the reaction time, the optimal ratio of the two reagents, as well as the influence of foreign substance were all investigated. Meanwhile, the mechanism of fluorescence recovery was also studied. Under the optimal conditions, the linear ranges of the calibration curves were 10-250 ng ml⁻¹ for calf thymus DNA (CT DNA) and 10-200 ng ml⁻¹ for yeast RNA. The detection limits were 6.8 ng ml⁻¹ for CT DNA and 6.3 ng ml⁻¹ for yeast RNA, respectively. The method has been applied to the analysis of practical samples and the recovery results were satisfactory.     

Electrochemical Behavior of Epinephrine at a Penicillamine Self-Assembled Gold Electrode,and its Analytical Application

The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode were investigated. The self-assembled electrode shows obvious electrocatalytic activity for the oxidation of epinephrine (EP). In phosphate buffer (pH 7.73), a sensitive oxidation peak was observed at 0.190V with the PCA modified Au electrode. The peak current is proportional to the concentration of EP in the range of 2.0×10^–56.0×10^–4molL^–1 and 5.0×10^–6 2.0×10^–4molL^–1 for cyclic voltammetry (CV) and differential pulse voltammetry (DPV) with the detection limits of 1.8×10^–7 and 1.3×10^–7molL^–1, respectively. The possible reaction mechanism is also discussed. The PCA self-assembled monolayer modified gold electrode is highly stable and can be applied to the determination of EP in practical injection samples. Application is simple, rapid and produces accurate results.     

A new fabrication process for a microchip electrophoresis device integrated with a three-electrode electrochemical detector

We report here a novel and simple process for the fabrication of a poly(methyl methacrylate) (PMMA)-based microchip electrophoresis device, integrated with a screen-printed three-electrode electrochemical detector that does not require a replicate mold. In this approach, a photoresist layer constitutes both an adhesion layer and side walls of 50 mum wide and 50 mum tall microfluidic channels on a screen-printed three-electrode PMMA substrate. Openings were drilled for buffer reservoirs on an additional piece of PMMA, then the final device was bonded in a PMMA/photoresist/PMMA sandwich configuration. This process is inexpensive, less time-consuming, and simpler compared with traditional fabrication methods. The combination of this PMMA-based microchip fabrication together with screen-printed electrode technology holds great promise for the mass production of a single-use micrototal analytical system. Successful determination of uric acid and L-ascorbic acid with the presented system validates its utility. In combination with a suitable electrochemical detector, this device holds much promise for the determination of other analytes in various biological samples for medical and clinical diagnosis.     

Cytotoxic sesterterpenes, 6-epi-ophiobolin G and 6-epi-ophiobolin N, from marine derived fungus Emericella variecolor GF10

Two new sesterterpenes, 6-epi-ophiobolin G (1) and 6-epi-ophiobolin N (3), and six known ophiobolins were isolated from the extracts of the fungus, Emericella variecolor GF10, which was separated from marine sediment. The planar structures of the new compounds were deduced from analysis of the 2D NMR spectra, and the stereochemistry was determined by extensive examination of the NOESY spectrum. Additionally, the configuration of the C-6 proton in ophiobolin G (2) was revised from α to β, and the unsolved stereochemistry of ophiobolin H (4) was determined by its physicochemical evidence and the chemical correlation with ophiobolin K (8). Ophiobolin K (8) showed cytotoxic activity against various tumor cell lines, including adriamycin-resistant mouse leukemia cells (P388), with IC₅₀ of 0.27-0.65 μM.     

Four New Nortriterpenoids from Phlomis umbrosa

Four new 28‐noroleanane‐derived spirocyclic triterpenoids, compounds 1 – 4 , were isolated from the rhizomes of Phlomis umbrosa. Their structures were elucidated on the basis of 1D‐ and 2D‐NMR analyses, in combination with high‐resolution MS experiments.