Search results for " Spectroscopy"
showing 10 items of 6851 documents
Magnetic Resonance Spectrobiopsy for Prediction of Isocitrate Dehydrogenase Mutation in Glioma
2020
Despite the existence of multimodal therapy paradigm, high-grade gliomas (HGGs) remain devastating tumors associated with one of the worst prognoses. Glioblastoma (GBM) is the most frequent reported histologic type with a median survival, after surgery and combined treatment with chemotherapy and radiotherapy, ranging from 12 to 16 months. The poor prognosis is due to the lack of therapeutic efficacy of chemical agents and irradiation in hypoxic tumor areas. Experimental studies have investigated several molecules with the aim to counteract several downstream signaling important in tumor progression, unfortunately without conclusive results. Several studies have shown that the extent of res…
Preparation and structural characterization of organotin(IV) complexes with ligands containing a hetero {N} atom and a hydroxy group or hydroxy and c…
2005
AbstractTwenty-two n-butyltin(IV) and t-butyltin(IV) complexes of ligands containing an –OH (–C@O) group or –OH and –COOHgroups and an aromatic {N} donor atom were prepared by metathetical reactions. On the basis of the FT-IR and Mo¨ssbauer spec-troscopic data, molecular structures were assigned to these compounds. The binding sites of the ligands were identified by means ofFT-IR spectroscopic measurements, and it was found that in most cases the organotin(IV) moiety reacts with the phenolic form ofthese ligands. In the complexes with –OH and –COOH functions, the –COOH group is coordinated to the organotin(IV) centres in amonodentate manner. The 119 Sn Mo¨ssbauer and the FT-IR studies suppor…
Towards Quantifying Non-Photosynthetic Vegetation for Agriculture Using Spaceborne Imaging Spectroscopy
2021
Non-photosynthetic vegetation (NPV) has been identified as priority variable in the context of new spaceborne imaging spectroscopy missions. In this study we provide a first attempt to quantify NPV biomass from these unprecedented data streams to be provided by multiple recently launched or planned instruments. A hybrid workflow is proposed including Gaussian process regression (GPR) trained over radiative transfer model (RTM) simulations and applying active learning strategies. A soybean field data set including two dates with NPV measurements on yellow and senescent (brown) plant organs was used for model validation, resulting in relative errors of 13.4%. This prototype retrieval model wa…
Crop nitrogen monitoring: Recent progress and principal developments in the context of imaging spectroscopy missions
2020
Abstract Nitrogen (N) is considered as one of the most important plant macronutrients and proper management of N therefore is a pre-requisite for modern agriculture. Continuous satellite-based monitoring of this key plant trait would help to understand individual crop N use efficiency and thus would enable site-specific N management. Since hyperspectral imaging sensors could provide detailed measurements of spectral signatures corresponding to the optical activity of chemical constituents, they have a theoretical advantage over multi-spectral sensing for the detection of crop N. The current study aims to provide a state-of-the-art overview of crop N retrieval methods from hyperspectral data…
Synthesis of Rosmarinic Acid Amides as Antioxidative and Hypoglycemic Agents
2019
Type 2 diabetes mellitus (T2DM) is an important metabolic disorder for which there is an urgent need for new antidiabetic drugs. α-Glucosidase inhibition is an established protocol for T2DM therapy. Because hyperglycemia causes oxidative tissue damage, the development of agents with both α-glucosidase inhibition and antioxidant activity from natural or natural-derived polyphenols such derivatives of rosmarinic acid (RA) represents an attractive therapeutic option. We report a study on amides 1-10 derived from RA and their evaluation for yeast α-glucosidase inhibition and antioxidant activity (DPPH and ORAC tests). All amides showed higher inhibitory activity than that of RA, were by far mor…
Solid microcrystalline dispersion films as a new strategy to improve the dissolution rate of poorly water soluble drugs: A case study using olanzapine
2016
In this study, we evaluate the dissolution rate enhancement of solid microcrystalline dispersion (SMD) films of olanzapine (OLZ) formulated with four water-soluble polymers namely poly(N-vinylpyrrolidone) (PVP), poloxamer 188 (P188), poloxamer 407 (P407) and Soluplus(®) (SLP). Prepared formulations were characterised to determine particle size, morphology, hydrogen bonding interactions, thermal characteristics as well as in vitro dissolution studies conducted under sink conditions (pH 6.8). Particle size of OLZ in all formulations ranged between 42 and 58μm. Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), Differential Scanning Calorimetry (DSC) and Hot-Stage…
Trap-assisted spectroscopy with REXTRAP
2007
International audience; As one of the fashionable techniques for nuclear spectroscopy experiments, the beam manipulation in gas-filled Penning traps permits the accurate measurement of some of the ground state properties of exotic nuclides. It was recently applied using REXTRAP for the measurement of the half-life of 38Ca, one of the 0+ → 0+ β-decaying nuclide of interest for the determination of the Ft value for super-allowed transitions, and the test of the unitarity of the CKM matrix. The experimental setup and the original method of beam purification adopted for this measurement is presented.
ATR-Spin: an open-source 3D printed device for direct cytocentrifugation onto attenuated total reflectance crystals.
2021
Infrared Spectroscopy (IR) enables the direct and rapid characterization of cells at the molecular level. Achieving a rapid and consistent cell preparation is critical for the development of Point-of-Care diagnostics for cell analysis. Here we introduce an open-source, 3D printed device for integrating the isolation, preconcentration, and measurement of attenuated total reflectance IR spectra of cells from biofluids. The tool comprises a disposable card for cytocentrifugation, equipped with magnets, which allows reproducible integration into the pathlength of the IR spectrophotometer. Preliminary results using cell media containing A459 cells indicate that this system enables a qualitative …
Magnetic dichroism in angle-resolved hard x-ray photoemission from buried layers
2011
This work reports the measurement of magnetic dichroism in angular-resolved photoemission from in-plane magnetized buried thin films. The high bulk sensitivity of hard x-ray photoelectron spectroscopy (HAXPES) in combination with circularly polarized radiation enables the investigation of the magnetic properties of buried layers. HAXPES experiments with an excitation energy of 8 keV were performed on exchange-biased magnetic layers covered by thin oxide films. Two types of structures were investigated with the IrMn exchange-biasing layer either above or below the ferromagnetic layer: one with a CoFe layer on top and another with a Co${}_{2}$FeAl layer buried beneath the IrMn layer. A pronou…
Mossbauer spectroscopic study of the thermal spin crossover in [Fe(II)(isoxazole)(6)](ClO(4))(2)
2008
The (57)Fe Mossbauer spectroscopy of mononuclear [Fe(II)(isoxazole)(6)](ClO(4))(2) has been studied to reveal the thermal spin crossover of Fe(II) between low-spin (S = 0) and high-spin (S = 2) states.Temperature-dependent spin transition curves have been constructed with the least-square fitted data obtained from the Mossbauer spectra measured at various temperatures between 84 and 270 K during a cooling and heating cycle. This compound exhibits an unusual temperature-dependent spin transition behaviour with T(C)(down arrow) = 223 and T(C)(up arrow) = 213 K occurring in the reverse order in comparison to those observed in SQUID observation and many other spin transition compounds. The comp…