Search results for "Spectroscopy"
showing 10 items of 10293 documents
Xyloglucan endotransglucosylase and cell wall extensibility
2011
Transgenic tomato hypocotyls with altered levels of an XTH gene were used to study how XET activity could affect the hypocotyl growth and cell wall extensibility. Transgenic hypocotyls showed significant over-expression (line 13) or co-suppression (line 33) of the SlXTH1 in comparison with the wild type, with these results being correlated with the results on specific soluble XET activity, suggesting that SlXTH1 translates mainly for a soluble XET isoenzyme. A relationship between XET activity and cell wall extensibility was found, and the highest total extensibility was located in the apical hypocotyl segment of the over-expressing SlXTH1 line, where the XET-specific activity and hypocotyl…
A new ursane-type triterpene oxoglucopyranoside from Crossopteryx febrifuga.
2019
Abstract A new saponin, 3-O-β-d-3-oxo-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (1), was isolated from the methanol extract of stem bark of Crossopteryx febrifuga together with the known 3β-d-glucopyranosyl-ursa-12,20(30)-diene-27,28-dioic acid (2), shanzhiside methyl ester (3), shanzhiside (4), β-sitosterol (5), β-sitosterol-3-O-β-d-glucopyranoside (6), ursa-12,20(30)-diene-27,28-dioic acid (7), hederagenin (8), and oleanolic acid (9). The structures were established by comprehensive interpretation of their spectral data 1D- (1H and 13C), 2D-NMR (1H-1H COSY, HMQC, HMBC), spectroscopic, and electrospray ionisation time-of-flight mass spectrometry analysis. The isolated compounds …
New Acyclic Cytotoxic Jasplakinolide Derivative from the Marine Sponge Jaspis splendens
2019
A new acylic jasplakinolide congener (2), another acyclic derivative requiring revision (4), together with two jasplakinolide derivatives including the parent compound jasplakinolide (1) were isolated from the Indonesian marine sponge Jaspis splendens. The chemical structures of the new and known compounds were unambiguously elucidated based on HRESIMS and exhaustive 1D and 2D NMR spectral analysis as well as a comparison of their NMR data with those of jasplakinolide (1). The isolated jasplakinolides inhibited the growth of mouse lymphoma (L5178Y) cells in vitro with IC50 values in the low micromolar to nanomolar range.
Conifer Needles as Thermoplastic Composite Fillers: Structure and Properties
2016
This study describes the properties of thermoplastic polymer composites based on polyethylene (of low and high density) and ethylene-propylene copolymers using various types of conifer needles (pine, spruce, fir, and cedar) as fillers. For the needles, thermogravimetric analysis (TGA) and TGA/Fourier transform infrared spectroscopy (TGA/FTIR) were performed to investigate their structures and thermal resistance, as required for the composite processing methods. Moreover, structural differences were studied for the analyzed fillers and composite materials (FTIR). The results were compared with the values obtained for composites with conifer wood flour. Composites with conifer needles (pine) …
2021
Centaurothamnus maximus (family Asteraceae), is a leafy shrub indigenous to the southwestern Arabian Peninsula. With a paucity of phytochemical data on this species, we set out to chemically characterize the plant. From the aerial parts, two newly identified guaianolides were isolated: 3β-hydroxy-4α(acetoxy)-4β(hydroxymethyl)-8α-(4-hydroxy methacrylate)-1αH,5αH, 6αH-gual-10(14),11(13)-dien-6,12-olide (1) and 15-descarboxy picrolide A (2). Seven previously reported compounds were also isolated: 3β, 4α, 8α-trihydroxy-4-(hydroxymethyl)-lαH, 5αH, 6βH, 7αH-guai-10(14),11(13)-dien-6,12-olide (3), chlorohyssopifolin B (4), cynaropikrin (5), hydroxyjanerin (6), chlorojanerin (7), isorhamnetin (8), …
Triterpene saponins of the root bark of Olax obtusifolia De Wild
2018
Abstract Four undescribed triterpenoid saponins together with five known and oleanolic acid were isolated from root bark of Olax obtusifolia De Wild. Their structures were elucidated by spectroscopic methods including 1D and 2D NMR experiments, in combination with mass spectrometry as 3-O-α- l -rhamnopyranosyl-(1→4)-α- l -rhamnopyranosyl-(1→3)-β- d -glucuronopyranosyloleanolic acid, 3-O-α- l -rhamnopyranosyl-(1→4)-α- l -rhamnopyranosyl-(1→3)-β- d -glucuronopyranosyloleanolic acid 28-O-β- d -glucopyranosyl ester, 3-O-α- l -rhamnopyranosyl-(1→3)-β- d -glucopyranosyl-(1→2)-[β- d -glucopyranosyl-(1→3)]-β- d -glucuronopyranosyloleanolic acid and 3-O-α- l -rhamnopyranosyl-(1→3)-β- d -glucopyranos…
Spectroscopic analysis of hot-water- and dilute-acid-extracted hardwood and softwood chips
2017
Hot-water and dilute sulfuric acid pretreatments were performed prior to chemical pulping for silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips to determine if varying pretreatment conditions on the original wood material were detectable via attenuated total reflectance (ATR) infrared spectroscopy. Pretreatment conditions varied with respect to temperature (130 °C and 150 °C) and treatment time (from 30 min to 120 min). The effects of the pretreatments on the composition of wood chips were determined by ATR infrared spectroscopy. The spectral data were compared to those determined by common wood chemistry analyses to evaluate the suitability of ATR spe…
Electrochemical polymerization of ambipolar carbonyl-functionalized indenofluorene with memristive properties
2019
Abstract Carbonyl-functionalized indenofluorene was electropolymerized with a high faradaic efficiency of 85% and the solid state properties of the resulting polymeric thin films were investigated. They displayed modular optical properties depending on their oxidation state. The approach used for inorganic semiconductors was applied to polyindeonofluorene derivative. Mott-Schottky analysis evidenced a switching from p-type to n-type electrical conduction, suggesting an ambipolar behaviour of the polymer. As an application, flexible organic memristors were fabricated and resistive switching properties were observed.
Electron Spin Resonance study of charge trapping in α-ZnMoO4 single crystal scintillator
2015
The origin and properties of electron and hole traps simultaneously appearing in a-ZnMoO4 scintillator after X-ray irradiation at low temperatures (T < 35 K) were studied by Electron Spin Resonance (ESR). ESR spectrum of the electron type trap shows pronounced superhyperfine structure due to the interaction of electron spin with nuclear magnetic moments of 95,97Mo and 67Zn lattice nuclei. Considering the nearly tetragonal symmetry of the center this allows us to identify the electron trap as an electron self-trapped at the (Mo(1)O4) 2 complex. Nearly 60% reduction of the spin–orbit coupling at the Mo(1) ion is caused by the overlap of the Mo and ligand oxygen orbitals indicating an essentia…
Plasmonic nanosensors reveal a height dependence of MinDE protein oscillations on membrane features
2018
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