Structure elucidation and NMR assignments of a new 6,9-cyclotetrahydrofuranlignan from Syringa pinnatifolia

A new 6,9-cyclotetrahydrofuranlignan, 3,3′-dimethoxy-4,4′-dihydroxy-8β,9β,8′α-6,9-cyclotetrahydrofuranlignan, was isolated from the stem of Syringa pinnatifolia Hems1.var. alashanensis MA. et S. Q. ZHOU. Its structures were elucidated on the basis of spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR.     

A Single Excitation‐Duplexed Imaging Strategy for Profiling Cell Surface Protein‐Specific Glycoforms

This work develops a site‐specific duplexed luminescence resonance energy transfer system on cell surface for simultaneous imaging of two kinds of monosaccharides on a specific protein by single near‐infrared excitation. The single excitation‐duplexed imaging system utilizes aptamer modified upconversion luminescent nanoparticles as an energy donor to target the protein, and two fluorescent dye acceptors to tag two kinds of cell surface monosaccharides by a dual metabolic labeling technique. Upon excitation at 980 nm, only the dyes linked to protein‐specific glycans can be lit up by the donor by two parallel energy transfer processes, for in situ duplexed imaging of glycoforms on specific protein. Using MUC1 as the model, this strategy can visualize distinct glycoforms of MUC1 on various cell types and quantitatively track terminal monosaccharide pattern. This approach provides a versatile platform for profiling protein‐specific glycoforms, thus contributing to the study of the regulation mechanisms of protein functions by glycosylation.     

Facile synthesis of ZnO nanoparticles for the photocatalytic degradation of methylene blue

Journal of Sol-Gel Science and Technology - ZnO nanoparticle photocatalysts with a grain size range of 20–100?nm were prepared via a simple sol–gel method and characterized by...     

Composite Mesoporous Silica Nanoparticles with Dual-color Afterglow for Cross-correlation-based Living Cell Imaging

Room temperature phosphorescence (RTP) materials are characterized with emission after removing the excitation source. Such long-lived emission feature possesses great potential in biological fluorescence imaging because it enables a way regarding temporal dimension for separating the interference of autofluorescence and common noises typically encountered in conventional fluorescence imaging. Herein, we constructed a new type of mesoporous silica nanoparticles (MSNs)-based composite nanoparticles (NPs) with dual-color long-lived emission, namely millisecond-level green phosphorescence and sub-millisecond-level delayed red fluorescence by encapsulating a typical RTP dye and Rhodamine dye in the cavities of the MSNs with the former acting as energy donor (D) while the latter as acceptor (A). Benefiting from the close D-A proximity, energy match between the donor and the acceptor and the optimized D/A ratio in the composite NPs, efficient triplet-to-singlet Förster resonance energy transfer (TS-FRET) in the NPs occurred upon exciting the donor, which enabled dual-color long-lived emission. The preliminary results of dual-color correlation imaging of live cells based on such emission feature unequivocally verified the unique ability of such NPs for distinguishing the false positive generated by common emitters with single-color emission feature.     

A sensitive method for determination of salvianolic acid A in rat plasma using liquid chromatography/tandem mass spectrometry

Salvianolic acid A (SAA), a major effective constituent of Salvia miltiorrhizas, is widely used in traditional Chinese medicine. A sensitive rapid analytical method was established and validated for SAA in rat plasma, which was further applied to assess the pharmacokinetics of SAA in rats receiving a single oral dose of SAA. The method used liquid chromatography tandem mass spectrometry in multiple reaction monitoring mode with chloramphenicol as the internal standard. A simple liquid-liquid extraction based on ethyl acetate was employed. The combination of a simple sample cleanup and short chromatographic run time (3 min) increased the throughput of the method substantially. The method was validated over the range 1.4-1000 ng/mL with a correlation coefficient >0.99. The lower limit of quantification was 1.4 ng/mL for SAA in plasma. Intra- and inter-day accuracies for SAA were 95-113 and 98-107%, and the inter-day precision was less than 12%. This method is more sensitive and faster than previous methods. After a single oral dose of 100 mg/kg of SAA, the mean peak plasma concentration (Cmax) of SAA was 318 ng/mL at 0.5 h, the area under the plasma concentration-time curve (AUC0-12 h) was 698 +/- 129 ng.h/mL, and the elimination half-life (T1/2) was 3.29 h.     

Cloning of Thermostable Cellulase Genes of <Emphasis Type="Italic">Clostridium thermocellum</Emphasis> and Their Secretive Expression in <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Screening for the powerful cellulase genes with improved activities remains a challenge for the biorefinery research. In this study, five cellobiohydrolase genes and one endoglucanase gene sourced from Clostridium thermocellum DSM 1237, cbhA, celK, celO, cel48Y, cel48S, and celA were cloned into a newly established tool vector pP43JM2 and expressed in two Bacillus subtilis strains, B. subtilis WB600 and B. subtilis WB800, respectively. Most of the cellulases produced in the B. subtilis recombinants were efficiently secreted into the culture medium. These secreted soluble proteins showed distinct cellulase activities using phosphoric acid swollen cellulose (PASC) as the substrate and they also demonstrated strong synergistic effects for PASC, Avicel cellulose, and the dilute acid pretreated corn stover. The current work provided a quick secretive cloning method for screening cellulase genes and may provide a host strain for constructing a consolidated bioprocessing platform with the capacity of secretive expression of multiple cellulases.     

A beta-keto ester as a novel, efficient, and versatile ligand for copper(I)-catalyzed C-N, C-O, and C-S coupling reactions

Employing ethyl 2-oxocyclohexanecarboxylate as a novel, efficient, and versatile ligand, the copper-catalyzed coupling reactions of various N/O/S nucleophilic reagents with aryl halides could be successfully carried out under mild conditions. A variety of products including N-arylamides, N-arylimidazoles, aryl ethers, and aryl thioethers were synthesized in good to excellent yields.     

Cobalt(II)‐Catalyzed C?H Alkynylation/Annulation with Terminal Alkynes: Selective Access to 3‐Methyleneisoindolin‐1‐one

A highly efficient cobalt(II)‐catalyzed alkynylation/annulation of terminal alkynes assisted by an N,O‐bidentate directing group is described. This protocol is characterized by wide substrate scope utilizing cheap cobalt catalysts, and offers a new approach to 3‐methyleneisoindolin‐1‐one, which can be converted into an oxadiazine salt in one step. Moreover, the directing group could be removed in three steps.     

便携式GC-MS在挥发性有机物应急监测中的应用

建立了便携式GC-MS测定空气中37种挥发性有机物(VOCs)的方法,采用便携式GC-MS配置的手持探头采集大气样品,然后用便携式GC-MS进行检测.该方法能快速、有效地对空气中的37种挥发性有机物进行定性和定量,具有相关性好(r>0.995)、检出限低(0.070×10-9 ～0.94×10-9 (体积分数))、精密度好(RSD小于7.7%)、准确度高(回收率为92% ～114%)的特点,适用于大气中挥发性有机污染物的应急监测.     

Dense layers of vertically oriented WO3 crystals as anodes for photoelectrochemical water oxidation

Films of crystalline WO(3) nanosheets oriented perpendicular to tungsten substrates were grown by a surfactant-free hydrothermal method, followed by sintering. The films exhibit photoelectrochemical oxygen evolution at low overpotential.