Search results for "fluorescence spectra"
showing 10 items of 14 documents
Investigating different skin and gastrointestinal tract (GIT) pathologies ex vivo by autofluorescence spectroscopy and optical imaging
2017
The skin neoplasias are on a second place in the world statistics of cancer incidence, and gastrointestinal tract (GIT) tumours are also in the “top ten” list. For the most of cutaneous and gastrointestinal tumours could be obtained better prognoses for patients, if an earlier and precise diagnostics procedure is applied. One of the most promising approaches for development of improved diagnostic techniques, is based on optical detection, and analysis of the signatures of biological tissues for detecting the presence of pathological alterations in the investigated objects. It is important to develop and combine novel diagnostic techniques for an accurate early stage diagnosis to improve the…
Correction: Calculation of vibrationally resolved absorption and fluorescence spectra of the rylenes
2020
Correction for ‘Calculation of vibrationally resolved absorption and fluorescence spectra of the rylenes’ by Jonas Greiner et al., Phys. Chem. Chem. Phys., 2020, 22, 2379–2385.
Multilayered samples reconstructed by measuring Kα/Kβ or Lα/Lβ X-ray intensity ratios by EDXRF
2013
Abstract In this paper a general method based on energy-dispersive X-ray fluorescence (EDXRF) analysis has been tested to assess its possible use as a tool to reconstruct the structure and determine the thickness of two and/or multi-layered materials. The method utilizes the X-ray intensity ratios of Kα/Kβ or Lα/Lβ peaks (or the ratio of these peaks) for selected elements present in multi-layered objects of various materials (Au alloys, gilded Cu, gilded Ag, gilded Pb, Ag–Au Tumbaga, stone surfaces with protective treatments, Zn or Nickel plating on metals). Results show that, in the case of multi-layered samples, a correct calculation of the peak ratio (Kα /Kβ and/or Lα/Lβ) of relevant ele…
High-Resolution Fluorescence Spectra of Airborne Biogenic Secondary Organic Aerosols: Comparisons to Primary Biological Aerosol Particles and Implica…
2021
Aqueous extracts of biogenic secondary organic aerosols (BSOAs) have been found to exhibit fluorescence that may interfere with the laser/light-induced fluorescence (LIF) detection of primary biological aerosol particles (PBAPs). In this study, we quantified the interference of BSOAs to PBAPs by directly measuring airborne BSOA particles, rather than aqueous extracts. BSOAs were generated by the reaction of d-limonene (LIM) or α-pinene (PIN) and ozone (O3) with or without ammonia in a chamber under controlled conditions. With an excitation wavelength of 355 nm, BSOAs exhibited peak emissions at 464–475 nm, while fungal spores exhibited peak emissions at 460–483 nm; the fluorescence intensit…
Development of Peat Processing Methods for Production of Innovative Products
2020
Synthesis or humification of humic substances (HSs) is the second widely applied organic compound transformation process after photosynthesis. Peat decomposition process results in a production of a HSs which has a high demand in agriculture, forestry, and gardening areas. Addition of the KOH is good option for environmental protection and K+ belongs to the nitrogen, potassium and phosphorous (NKP) mineral component. A homogenization process in a customize for commerce, where peat treatment technology was improved with the help of the cavitation effect. This effect was provided with the help of the high-speed mixer-disperser (HSMD) developed at Riga Technical University. Mechanical cavitati…
Direct excitation of the “dark”b3Πstate predicted by deperturbation analysis of theA1Σ+−b3Πcomplex in KCs
2010
The diode-laser-induced fluorescence spectra $b {}^{3}{\ensuremath{\Pi}}_{\ensuremath{\Omega}=0}^{+}\ensuremath{\rightarrow}{X}^{ 1}{\ensuremath{\Sigma}}^{+}$ originated from the rovibronic levels of the ``dark'' triplet $b {}^{3}{\ensuremath{\Pi}}_{\ensuremath{\Omega}=0}^{+}$ state of KCs dimers were recorded with a Fourier transform spectrometer with a resolution of 0.03 cm${}^{\ensuremath{-}1}$. Term values of 30 rovibronic levels $({v}_{b0}^{*}\ensuremath{\in}[14,18];{J}^{\ensuremath{'}}\ensuremath{\in}[47,134])$ below the minimum of perturbing $A {}^{1}{\ensuremath{\Sigma}}^{+}$ state were determined with 0.003--0.01 cm${}^{\ensuremath{-}1}$ uncertainty. The optimal excitation and dete…
Proton-Induced Multiple Changes of the Absorption and Fluorescence Spectra of Amino-Aza-Oligo(Phenylenevinylene)s
2008
Fluorescent dyes with a high sensitivity of their optical spectra towards changes of the environment were prepared via aldol condensation or Horner olefinations. The main chromophore is a quadrupolar N-substituted 1,4-distyrylbenzene which allows protonation and complexation at various positions resulting in a series of different and significant changes of the optical spectra. The sensitivity of the absorption and emission spectra on solvent polarity, acid, and cations is reported.
Bis(pyridylvinyl)diaminobenzenes: synthesis, acidochromism and solvatochromism of the fluorescence
2005
Abstract C2-symmetrical 1,4-distyrylbenzenes with 4-dimethylaminobenzene or pyridine as terminal rings, and propyloxy or dipropylamino groups in the central 2,5-positions were prepared. Solvatochromism of the absorption is small, but more pronounced in the fluorescence spectra. Some compounds exhibit huge Stokes shifts. Acid strongly alters the fluorescence: red shifts and decreasing quantum yields is the general result, but depending on the position and character of the basic sites, a strong recovery of fluorescence efficiency combined with large hypsochromic shifts may result in highly acidic solutions.
Untersuchungen zur Konformerenvielfalt von mono- und 2,5-dialkoxysubstituierten Poly(1,4-phenylenethenylen)en
1994
Investigations on the Conformational Variety of Mono- and 2,5-Dialkoxy Substituted Poly(1,4-phenyleneethenylene)s The alkoxy substituted poly(1,4-phenyleneethenylene)s 1 and 2 can principally exist in an enormous variety of conformers (table 1). However, force field calculations (MMX) reveal a far-reaching restriction to a relatively small number of non planar conformers with minimized steric energy. The decisive criterion is due to the interaction between the oxygen atoms and the olefinic hydrogens. An increasing steric hindrance should lead to higher twist angles θ in the main chain and hence to a shorter effective conjugation length. Such an effect could play a minor role between the uns…
Differences of stabilized organic carbon fractions and microbiological activity along Mediterranean Vertisols and Alfisols profiles
2010
This study examined the chemical and structural properties of humic substances and microbiological activity in order to verify differences in carbon dynamics along soil profiles in two Vertisols (Typic Haploxerert and Xeric Epiaquert) and two Alfisols (Mollic Haploxeralf and Ultic Haploxeralf) developed under Mediterranean climate in Italy. Humification parameters, thermal methods, including differential scanning calorimetry (DSC) and thermogravimetry (TG), together with Fourier transform infrared (FT-IR) and fluorescence spectroscopies were used to characterize humic acids (HA). Microbiological activity of soils was assessed by basal respiration, metabolic quotient (qCO2) and Cmic:Corg rat…