Search results for "Spectroscopy."
showing 10 items of 9110 documents
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
6 p.-4 fig.
Modelling IR Spectra of Sulfonated Polyether Ether Ketone (SPEEK) Membranes for Fuel Cells
2020
Authors acknowledge support from LSC project No 2014/666 ERDF and students ( ) support from project 2DP/2.1.1.1.0/14/APIA/VIAA/009.
II) Wood pellets for home heating can be considered environmentally friendly fuels? Heavy metals determination by inductively coupled plasma-optical …
2016
Abstract The aim of the present study was to determine the concentrations of twelve potentially hazardous elements in wood pellet ashes obtained by the combustion of 13 pellet brands for sale in Italy, the impact of adding the ashes to soils and health risk of operator due to dust exposure. Samples were analysed by Inductively Coupled Plasma Optical Emission Spectrometry. The concentrations of heavy metals in ashes from stoves ranged from 0.41 to 7.2 mg kg − 1 for As, from 1.3 to 12 mg kg − 1 for Sb, from 1.8 to 12 mg kg − 1 for Zn, from 0.23 to 0.8 mg kg − 1 for Pb, from 0.18 to 2.8 mg kg − 1 for Ni, from 0.09 to 1.0 mg kg − 1 for Cd, from 0.46 to 3.4 mg kg − 1 for Cr, from 0.94 to 2.7 mg …
Direct laser welding of pure titanium to austenitic stainless steel
2018
Abstract Direct butt joining of pure titanium to 316L stainless steel with continuous Yb:YAG laser was performed with variation of the beam offset from joint line. Mechanical properties of samples were evaluated by tensile tests and three-point flexural tests. The fractured surfaces and cross sections of welds were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). Tensile properties of welds were strongly determined by the beam offset from joint line and are well described by Weibull statistics. Ultimate tensile strength of 174 ± 69 MPa and ultimate flexural strength of 297 ± 48 MPa were obtained. Brittle fracture took place in…
Transformation of Construction Cement to a Self-Healing Hybrid Binder
2019
A new biomimetic strategy to im prove the self-healing properties of Portland cement is presented that is based on the application of the biogenic inorganic polymer polyphosphate (polyP), which is used as a cement admixture. The data show that synthetic linear polyp, with an average chain length of 40, as well as natural long-chain polyP isolated from soil bacteria, has the ability to support self-healing of this construction material. Furthermore, polyP, used as a water-soluble Na-salt, is subject to Na+/Ca2+ exchange by the Ca2+ from the cement, resulting in the formation of a water-rich coacervate when added to the cement surface, especially to the surface of bacteria-containing cement/c…
Onset of cohesion in cement paste
2004
It is generally agreed that the cohesion of cement paste occurs through the formation of a network of nanoparticles of a calcium-silicate-hydrate ("C-S-H"). However, the mechanism by which these particles develop this cohesion has not been established. Here we propose a dielectric continuum model which includes all ionic interactions within a dispersion of C-S-H particles. It takes into account all co-ions and counterions explicitly (with pure Coulomb interactions between ions and between ions and the surfaces) and makes no further assumptions concerning their hydration or their interactions with the surface sites. At high surface charge densities, the model shows that the surface charge of…