Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

An experimental design approach using response surface techniques to obtain optimal liquid chromatography and mass spectrometry conditions to determine the alkaloids in Meconopsi species

A statistic approach using response surface methodology (RSM) for optimization of the ultra-high performance liquid chromatography (UHPLC) gradient and ionization response of electrospray ionization mass spectrometry (ESI-MS) to analyze the main alkaloids from the plant matrices of six Meconopsi species is presented. The optimization was performed with Box–Behnken designs (BBD) and the multicriteria response variables were described using global Derringer's desirability. Four parameters of UHPLC and six major parameters of ESI-MS were investigated for their contribution to analytes separation and response, leading to a total of 27 and 54 experiments being performed for each instrument, respectively. Quantitative analysis of four main alkaloids in nine samples from six Meconopsis species was employed to evaluate the statistical significance of the parameters on UHPLC–QTOF/ESI-MS analytes response. The results indicated that the optimized UHPLC–QTOF-MS method is very sensitive with the limit of detections (LODs) ranging from 0.5 to 0.1 ng/ml. The overall intra-day and the inter-day variations were less than 2.45%. The recovery of the method was in the range of 94.3–104.8% with RSD less than 4.0%. This approach has important implication in sensitivity enhancement of the ultra-trace determination of alkaloids from complex matrixes in the fields of natural products, metabolomics and pharmacokinetics.     

Prepolymer film growth by adsorption out of solution on silicon and aluminium

A cyanurate prepolymer has been applied to smooth silicon wafers or to distinctly structured aluminium coatings. The surface composition of the substrates has been investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean tickness of the prepolymer film has been adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon/aluminium, spin/dip coating) in the mean film thickness range from 1 to 50 nm.     

Optimisation of ultra-performance LC conditions using response surface methodology for rapid separation and quantitative determination of phenolic compounds in Artemisia minor

A method that couples rapid, sensitive, reproducible and accurate ultra-performance LC (UPLC) with quadrupole-TOF-MS was established for the first simultaneous qualitative and quantitative analysis of phenolic compounds in Artemisia minor. Box-Behnken designs (BBDs) were applied as an effective tool to optimise major parameters that influence the resolution of UPLC, including three gradient steps and column temperature. Under optimal UPLC conditions, a total of 23 phenolic compounds in the crude methanol extracts of A. minor were well separated on a Waters Acquity UPLC BEH C(18) column (100×2.1?mm, 1.7?μm particle size) within 16.5?min, and the compounds were unequivocally or tentatively identified via comparisons with authentic standards and literature. In this study, a total of six major phenolic compounds were quantified in A. minor and the method was validated to be sensitive, precise and accurate within the LOD from 1.24 to 5.27?μg/mL, and the overall intra- and inter-day variations in detection were less than 3.76%. The recovery of the method ranged from 97.9 to 103.8% with RSDs that were less than 5.8%. These results demonstrate that this approach has the potential for quality control of A. minor and other Tibetan herbal medicines.     

New Eremophilenolides from Senecio dianthus

From the aerial parts of Senecio dianthus, four new eremophilenolides ( 1 – 4 , resp.) and one new eremophilenolide alkaloid ( 5 ), of the relatively uncommon eremophilenoid‐type sesquiterpenoid lactones, were isolated together with three known sesquiterpenoid lactones, 10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 6 ), 8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 7 ), and 10α‐hydroxy‐1‐oxoeremophila‐7(11),8(9)‐dien‐12,8‐olide ( 8 ). On the basis of IR, MS, and NMR data, particularly 2D‐NMR analyses, the structures of the new compounds were established as: 2β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 1 ), 6β‐(angeloyloxy)‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 2 ), 2β‐(angeloyloxy)‐8β,10β‐dihydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 3 ), 2β‐(angeloyloxy)‐8α‐hydroxyeremophila‐7(11),9(10)‐dien‐12,8β‐olide ( 4 ), and 8β‐amino‐10β‐hydroxyeremophil‐7(11)‐en‐12,8α‐olide ( 5 ). In addition, the relative configuration of 1 was corroborated by X‐ray diffraction analysis.     

2-Harmonic Curves Isometrially Immersed in a Surface

In this paper,the author proves the necessary and sufficient condition for the existenceof 2-harmonically and isometrically immersed curves in a 2-dimensinonal surface N■IE~3.     

Secoiridoid Glycosides from Swertia mileensis

From the MeOH extract of the aerial parts of Swertia mileensis, four new secoiridoid glycosides were isolated, 4′‐O‐[(E)‐caffeoyl]swertiamarin ( 1 ), 4′‐O‐[(Z)‐coumaroyl]swertiamarin ( 7 ), 6′‐O‐[(E)‐coumaroyl]swertiamarin ( 8 ), and 6′‐O‐[(Z)‐coumaroyl]swertiamarin ( 9 ), together with five known compounds. Their structures were elucidated by NMR spectroscopy and tandem mass spectrometry. Detailed HPLC/MS analyses and MS/MS fragmentation pathways are discussed for the identification of the swertiamarin‐derived (E)/(Z) isomers 6 / 7 and 8 / 9 .