Search results for "Spectrum analysis"
showing 10 items of 287 documents
Indirect oxidation of amino acid phenylhydrazides by mushroom tyrosinase.
2006
We have investigated oxidation of amino acid phenylhydrazides by mushroom tyrosinase in the presence of 4-tert-butylcatechol and N-acetyl-l-tyrosine. Spectrophotometric measurements showed gradual disappearance of 4-tert-butyl-o-benzoquinone, generated by oxidation of 4-tert-butylcatechol with sodium periodate, after addition of amino acid phenylhydrazides. However, the presence of the phenylhydrazides did not influence the concentration of 4-tert-butyl-o-benzoquinone formed during enzymatic oxidation. Oxygen consumption measurements demonstrated that in a mixture both compounds were oxidized but the reaction rate was proportional to the concentration of the catechol. In the oxidation of N-…
Multispectral, Fluorescent and Photoplethysmographic Imaging for Remote Skin Assessment
2017
Optical tissue imaging has several advantages over the routine clinical imaging methods, including non-invasiveness (does not change the structure of tissues), remote operation (avoids infection) and ability to quantify the tissue condition by means of specific image parameters. Dermatologists and other skin experts need compact (preferably pocket-size), self-sustained and easy-to-use imaging devices. The operational principles and designs of ten portable in-vivo skin imaging prototypes developed at the Biophotonics Laboratory of Institute of Atomic Physics and Spectroscopy, University of Latvia during the recent five years are presented in this paper. Four groups of imaging devices are con…
The hyperfine structure in the rotational spectra of D2(17)O and HD(17)O: Confirmation of the absolute nuclear magnetic shielding scale for oxygen
2015
Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono- and bideuterated-water containing (17)O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spin-rotation (SR) and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular, the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimental…
Bioactive glass ions induce efficient osteogenic differentiation of human adipose stem cells encapsulated in gellan gum and collagen type I hydrogels
2019
Abstract Background Due to unmet need for bone augmentation, our aim was to promote osteogenic differentiation of human adipose stem cells (hASCs) encapsulated in gellan gum (GG) or collagen type I (COL) hydrogels with bioactive glass (experimental glass 2-06 of composition [wt-%]: Na2O 12.1, K2O 14.0, CaO 19.8, P2O5 2.5, B2O3 1.6, SiO2 50.0) extract based osteogenic medium (BaG OM) for bone construct development. GG hydrogels were crosslinked with spermidine (GG-SPD) or BaG extract (GG-BaG). Methods Mechanical properties of cell-free GG-SPD, GG-BaG, and COL hydrogels were tested in osteogenic medium (OM) or BaG OM at 0, 14, and 21 d. Hydrogel embedded hASCs were cultured in OM or BaG OM fo…
Optical retarder system with programmable spectral retardance.
2014
An optical system that works as a retarder waveplate with programmable spectral retardance is proposed. The system is based on a pixelated liquid crystal on silicon (LCoS) spatial light modulator (SLM). The input light beam is spectrally dispersed and different spectral components are projected onto different pixels of the LCoS-SLM. A different retardance is then addressed for each pixel, adapted to the incoming wavelength. Light reflected from the SLM is then recombined by the same setup. In this way a programmable polarization spectrum can be encoded. We illustrate the broadband characterization that is required for proper use of the system. Then several examples are shown, including spec…
Identifying yeasts using surface enhanced Raman spectroscopy
2019
Made available in DSpace on 2019-10-06T15:40:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-05 Tekes Academy of Finland Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The molecular fingerprints of yeasts Saccharomyces cerevisiae, Dekkera bruxellensis, and Wickerhamomyces anomalus (former name Pichia anomala) have been examined using surface-enhanced Raman spectroscopy (SERS) and helium ion microscopy (HIM). The SERS spectra obtained from cell cultures (lysate and non-treated cells) distinguish between these very closely related fungal species. Highly SERS active silver nano-particles suitable for detecting complex biomolecules were fabricated using a simple synt…
Concentriols B, C and D, three squalene-type triterpenoids from the ascomycete Daldinia concentrica
2002
Abstract Three squalene-type triterpenoids named concentricols B, C and D ( 1 – 3 ) were isolated from the ethyl acetate extract of fruiting bodies of the xylariaceous ascomycete Daldinia concentrica . Their absolute structures were elucidated by analysis of 2D NMR, MS, IR and UV spectra, and the modified Mosher's method.
Activity of lupane triterpenoids from Maytenus species as inhibitors of nitric oxide and prostaglandin E2
2005
In the present study, we report that three new lupane triterpenes (1-3), in addition to 16 known ones (4-19), were isolated from the root bark of Maytenus cuzcoina and the leaves of Maytenus chiapensis. Their structures were elucidated by spectral analysis, including homonuclear and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC, and HMBC). The natural compounds and derivatives 6a, 6b, 9a, and 9b have been tested for potential anti-inflammatory activity, and several compounds including 3-epicalenduladiol (2), 11alpha-hydroxy-glochidone (3), rigidenol (6), acetoxy-rigidenol (6a), 11alpha-acetoxy-30-chloro-3-oxo-lup-20(29)-ene (6b), betulin (9), 28-acetoxy-betulin (9a), epibetul…
Annelated pyrrolo-pyrimidines from amino-cyanopyrroles and BMMAs as leads for new DNA-interactive ring systems.
2005
The efficient one-pot synthesis of several new tricyclic systems of type 1 and 2, obtained from the reaction of substituted 2-amino-3-cyanopyrroles and 3-amino-4-cyanopyrroles with BMMAs, is reported. The duration and yields of the reaction strongly depend on the reactivity of the starting pyrrole and on the size of the ring to be formed. Mechanist features of the reaction were investigated and proposed by studying also the reactivity of a 3-aminopyrrole-2,4-dicyano substituted. The method reported represents the first example of the use of BMMA reagents in combination with pyrrole derivatives and allows an easy and versatile entry to a large number of hitherto unknown pyrrolo-pyrimidines f…
Crystal structure of [Cu(N-quinolin-8-yl-p-toluenesulfonamidate)2]: study of its interaction with DNA and hydrogen peroxide
2001
A new copper complex with N-quinolin-8-yl-p-toulenesulfonamide has been prepared and characterised. The compound crystallises in the triclinic system, space group P1, with a=13.457(3), b=15.067(5), c=18.589(3) A; α=112.05(2), β=93.92(2), γ=108.30(2)° and Z=4. The geometry of the Cu(II) ion is distorted square planar. The N-quinolin-8-yl-p-toulenesulfonamidate anion behaves as a bidentate ligand through the N s u l f o n a m i d a t e and N q u i n o l i n e atoms. The complex does not cleave DNA in the presence of hydrogen peroxide.