Synthesis,Characterization, and Crystal Structure of One Novel Indolo[3,2-b]carbazole Derivative

Indolocarbazole derivatives have been reported to be promising organic semicon- ductor candidates and electroluminescent （EL） materials. One novel indolocarbazole derivative, 2,8-acetyl-5,11-dihexyl-6,12-（di-p-tolyl）-5,11-indolo[3,2-b]carbazole （YK4）, has been synthesized, and its crystal structure has also been carefully studied. YK4 is triclinic, space groups Pi with a = 9.409（5）, b = 13.974（5）, c = 15.488（5） A, α = 90.281（5）, β = 105.456（5）, Z= 93.728（5）°, M,. = 688.94, V= 1958.1（14） A3, Z = 2, Dc.= 1.168 g/cm-3,μ = 0.070 mm-1, F（000） = 740, Rint = 0.0475, R （I〉 20（/）） = 0.1146, wR （I〉 20（/）） = 0.2186, R（all data） = 0.2192 and wR （all data） = 0.2701. Like other indolo[3, 2-b]carbazole derivatives which were introduced in the 5- and 11-positions, the intermolecular short contacts are localized between the pendant groups and acetyl groups of the neighboring indolocarbazole molecules. The molecule of YK4 possesses poor face-to-face π-π stacking between two adjacent molecules in the crystal. The calculated bond lengths and bond angles of YK4 also proved the result of crystallography.     

T-symmetric 40-nucleus silver clusters assembled by hetero-anions

We report two anion-templated Ag₄₀ clusters, [Ag₄₀(E)₄(SO₄){S₂P(OEt)₂}₂₄](PF₆)₆ (E = S, 1 ; Se, 2 ). The anionic templates were generated in situ from the decomposition of dithiophosphate (dtp) ligands. The extrusion of sulfur undergoes disproportionation reactions to generate sulfide and sulfate anions, which provide the source of templates in the subsequent cluster assembly reactions. Two Ag₄₀ clusters display high similarity in their structures. The sulfide (selenide) anions and the central sulfate anion reveal a six-coordinate and a rare dodecametallic dodecaconnective pattern, respectively. Four near-equivalent [Ag₁₀(E){S₂P(OEt)₂}₆]²⁺ motifs were assembled via the connection of central sulfate anion to construct Ag₄₀ clusters. The cluster cation, [Ag₄₀(E)₄(SO₄){S₂P(OEt)₂}₂₄]⁶⁺, displayed in T symmetry, is unprecedented in anion-templated silver clusters.     

超高效液相色谱-串联质谱法鉴定猪肉的特异性肽生物标志物

以亲缘关系较近的猪、牛和羊3个物种的肌肉组织为研究对象,采用超高效液相色谱-串联质谱(UPLC-MS),筛选并确认了猪物种肉特异性肽生物标志物.3种纯肉样品经蛋白质提取、胰蛋白酶消化和UPLC-TripleTOF-MS分离鉴定,得到的总离子流图谱(TIC)与Uniprot蛋白质数据库对比分析,筛选出3个物种肉的3种高丰度同源蛋白和8种潜在的肽生物标志物;潜在的肽生物标志物经QTRAP-MS质谱的多反应模式(MRM)分析,最终确认了猪物种肉的5种肽生物标志物,其中3种肽生物标志物未见文献报道.     

硅基超薄多孔氧化铝膜的制备

将二次阳极氧化法应用于硅基铝膜的制备, 在草酸溶液中得到了厚度可控的硅基超薄多孔氧化铝膜(PAM), 厚度小于100 nm. 实验中记录了氧化电流随时间的实时变化曲线, 发现硅衬底的氧化电流在大幅下降前有一小幅波动. 对应于Al/Si界面的氧化过程中, 孔洞底部之间的残留铝岛被优先氧化, 可将此作为终止铝氧化的标志. 扫描电镜(SEM)观察表明, 二次氧化提高了孔洞分布的均匀性, 使得孔在一定的区域内呈现有序六角分布.这种模板可进一步用于硅基纳米器件和纳米结构的制备.     

Highly diastereoselective enolate addition of O-protected alpha-hydroxyacetate to (S(R))-tert-butanesulfinylimines: synthesis of taxol side chain

The taxol side chain (S(R),2R,3S)-N-tert-butanesulfinyl-O-Boc-3-phenylisoserine benzyl ester 4c was synthesized through a lithium enolate addition of O-Boc-alpha-hydroxyacetate benzyl ester 5c to benzylidene (S(R))-tert-butanesulfinamide 6a in excellent yield and diastereoselectivity. By similar approach, a series of enantiopure 3-substituted isoserine benzyl esters 4 useful for the semi-syntheses of taxol derivatives were also prepared in high to excellent yields and diastereoselectivities. The diastereoselective addition mechanism was discussed on the basis of the experimental observation.     

Capillary electrophoresis‐laser‐induced fluorescence detection of rat brain catecholamines with microwave‐assisted derivatization

In this study, a rapid and sensitive method is described for the catecholamines detection in rat brain. CE with LIF detection for the determination of FITC derivatized catecholamines (dopamine, epinephrine, and norepinephrine) was demonstrated. Conventional water bath and microwave‐assisted derivatization methods were employed and a significant reduction in the derivatization time from 2 h for the conventional water bath at room temperature (ca. 25°C) to 2 min for the microwave‐assisted derivatization was achieved. Online sample concentration of field‐amplified sample stacking (FASS) method was employed to achieve higher sensitivities (the detection limits obtained in the normal injection mode ranged from 2.6 to 4.5 ng L^?1 and in the FASS mode ranged from 22 to 34 pg L^?1). Furthermore, this microwave‐assisted derivatization CE–LIF method successfully determined catecholamines in rat brain with as low as 100 ng L^?1 (FASS mode) to 10 μg L^?1 (normal injection mode). This CE–LIF method provided better detection ability when compared to the best reports on catecholamines analyses.     

Sequence Pattern Correlation of Amino-Acid in Collision-Induced -Dissociation Electrospray Ionization Mass Spectrometry

Briefly, the experimental mass spectrum is defined as X_(i)(#em/em#=1,2,...n)and the guessed sequence pattern in an estimated order is defined as Y_(k) (k=1,2,...n). For the discrete signals in mass spectra, the cross-correlation coefficient of C_xy,can be then given by.     

Effect of Yellowing Duration on the Chemical Profile of Yellow Tea and the Associations with Sensory Traits

The yellowing process is the crucial step to form the characteristic sensory and chemical properties of yellow tea. To investigate the chemical changes and the associations with sensory traits during yellowing, yellow teas with different yellowing times (0–13 h) were prepared for sensory evaluation and chemical analysis. The intensities of umami and green-tea aroma were reduced whereas sweet taste, mellow taste and sweet aroma were increased under long-term yellowing treatment. A total of 230 chemical constituents were determined, among which 25 non-volatiles and 42 volatiles were the key chemical contributors to sensory traits based on orthogonal partial least squares discrimination analysis (OPLS-DA), multiple factor analysis (MFA) and multidimensional alignment (MDA) analysis. The decrease in catechins, flavonol glycosides and caffeine and the increase in certain amino acids contributed to the elevated sweet taste and mellow taste. The sweet, woody and herbal odorants and the fermented and fatty odorants were the key contributors to the characteristic sensory feature of yellow tea with sweet aroma and over-oxidation aroma, including 7 ketones, 5 alcohols, 1 aldehyde, 5 acids, 4 esters, 5 hydrocarbons, 1 phenolic compound and 1 sulfocompound. This study reveals the sensory trait-related chemical changes in the yellowing process of tea, which provides a theoretical basis for the optimization of the yellowing process and quality control of yellow tea.     

Characterize the Alkaline Lipase by CIEF,HPLC and MS

Lipase is one kind of enzyme, which is useful in the home laundry in recent years. The study of lipase is attracting more and more attentions. And the gene engineering has produced many different kinds of lipase. Some heterogeneity of the alkaline lipase is extracted from penicillin cyclopium PG37 in the first time. Results of the database searching with the N-terminal sequence demonstrate that those proteins are new and have little homogenous with order lipases. All properties of this lipase, which has been studied, suggest that the enzyme could be used as a home laundry product ingredient. Thus, it is very important to characterize the protein and to study the reaction with the antibody^[1].