Toonamicrocarpavarin, a new tirucallane-type triterpenoid from Toona Ciliata.

Toonamicrocarpavarin (1), a new tirucallane-type triterpenoid, along with eight known ones, piscidinol A (2), toonaciliatavarin E (3), toonayunnanin A (4), 7-acetyneotrichilenone (5), hispidol A (6), odoratone (7), phellochin (8), toonaciliatavarin D (9), were isolated from T. ciliata. Their structures were identified on the basis of ESIMS, HREIMS and 1 D/2D NMR analysis. The cytotoxic activity of the new compound was also evaluated. All compounds were obtained from T. ciliata for the first time, which plays an important role in chemotaxonomy of the plant T. ciliata.

The Effect of Potential on Surface Characteristic and Corrosion Resistance of Anodic Oxide Film Formed on Commercial Pure Titanium at the Potentiodynamic-Aging Mode.

Anodic oxidation treatment of commercially pure titanium was carried out at the voltages of 10, 30, 50 V in 0.5 M H2SO4 solution at the potentiodynamic-aging mode so as to obtain the effects of the anodic potential on the surface characteristic and corrosion resistance of the anodic oxide film. The influences of potential on the surface morphology, the roughness, the crystalline behavior, the chemical composition and the corrosion resistance of the anodic oxide films were investigated by using scanning electron microscopy (SEM), atomic force microscope (AFM), Raman spectrum, X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization curves and electrode impedance spectroscopy (EIS). The results show that increasing anodic potential at the potentiodynamic-aging mode can significantly enhance thickness, flatness, crystallization, chemical stability, and corrosion resistance of anodic oxide film.

A sensitive and selective enzyme-linked immunosorbent assay for the analysis of Para red in foods.

Para red is a synthetic dye and a potential genotoxic carcinogen. A hapten mimicking Para red structure was synthesized by introducing a carboxyl to the naphthol part of Para red and coupled to carrier protein to form an immunogen for the production of specific antibodies. A sensitive and selective enzyme-linked immunosorbent assay (ELISA) was developed for the detection of Para red in food samples. The limit of detection and inhibition half-maximum concentrations of Para red in phosphate buffered saline with 10% methanol were 0.06 and 2.2 ng mL(-1), respectively. Cross-reactivity values of the ELISA with the tested compounds including Sudan red I, II, III, IV, and G, sunset yellow, 2-naphthol, and 4-nitroaniline were ≤0.2%. This assay was used to determine Para red in tomato sauce, chilli sauce, chilli powder and sausage samples after ultrasonic extraction, cleanup and concentration steps. The average recoveries, repeatability (intraday extractions and analysis), and intra-laboratory reproducibility (interday extractions and analysis) were in the range 90-108%, 4-12% and 8-17%, respectively. This assay was compared to a high-performance liquid chromatographic method for 28 samples, displaying a good correlation (R(2) = 0.95). Para red residues in 53 real world samples determined by ELISA were below the limit of detection.

Alternative chiral thiols for preparation of chiral CdS quantum dots covered immediately by achiral thiols.

Developing of alternative chiral thiol stabilizers from the assembly of achiral thiol (e.g. thioglycolic acid) and chiral ligand (e.g. arginine) via both hydrogen bonding and electrostatic interactions was proposed and successfully applied to an efficient preparation of chiral CdS quantum dots (QDs). Chiral CdS QDs capped mainly with achiral thioglycolic acid were also obtained that may allow the chiral QDs to be modified for extended applications.

Quantitative analysis of the neonicotinoid insecticides imidacloprid and thiamethoxam in fruit juices by enzyme-linked immunosorbent assays.

Rapid and sensitive ELISAs have been applied to analyze imidacloprid and thiamethoxam residues in apple, grape, orange, and peach juices after simple dilution of the samples without any extraction and cleanup. The matrix interference of the fruit juices was eliminated after 100-fold dilution, and the ELISAs gave method LODs of imidacloprid and thiamethoxam in fruit juices down to 20 and 5 ng/g, respectively. Average recoveries of imidacloprid and thiamethoxam from the spiked fruit juices were in the range of 92-115% and 87-118%, respectively. The CVs of the recoveries ranged from 3 to 19% and from 6 to 19% for imidacloprid and thiamethoxam, respectively. The ELISA results were comparable to those obtained by a reference HPLC/MS method using pesticide-spiked samples, with reasonable correlation coefficients between 0.89 and 0.93 and regression coefficients (slopes) between 0.75 and 0.94.

Determination of marbofloxacin residues in beef and pork with an enzyme-linked immunosorbent assay.

Marbofloxacin is a fluoroquinolone veterinary antibiotic. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of marbofloxacin using polyclonal antibody. The half-maximum inhibition concentrations (IC(50)) and limit of detection (LOD, calculated as IC(20)) of the ELISA for marbofloxacin in phosphate buffer were 4.6 and 0.6 ng/mL, respectively. The assay showed little cross-reactivity with marbofloxacin structural analogues, except for ofloxacin (148%). Matrixes from the extracts of beef and pork muscle have shown a significant influence on the ELISA. Standard curves of ELISA for marbofloxacin in the extracts of the appropriate marbofloxacin-free control muscles were used in the analysis of marbofloxacin in the animal muscles without any cleanup. The average recoveries of intra- and interassay for marbofloxacin from fortified muscle samples, at five concentrations of 10, 50, 100, 500, and 1000 ng/g, were 87-93 and 84-95%, respectively. The LOD of this assay for marbofloxacin in real muscle extracts was 0.8 ng/mL. A survey of 55 animal muscle samples purchased from local markets by the ELISA was conducted, and marbofloxacin was detected in one of them at a concentration of 22 ng/g. This positive sample was validated by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) to be 28 ng/g of marbofloxacin.