Spectroanalytical Parameters of Fungal Metabolites. II. Luminescence of Griseofulvin

1972 ◽  
Vol 55 (6) ◽  
pp. 1300-1304
Author(s):  
W C Neely ◽  
J R Mcduffie
Keyword(s):  
Thin Layer ◽  
Fluorescence Lifetime ◽  
Light Exposure ◽  
Emission Spectra ◽  
Fungal Metabolites ◽  
Fluorescence Excitation ◽  
Phosphorescence Lifetime ◽  
Phosphorescence Emission ◽  
The Mean ◽  
Luminescence Characteristics

Abstract I n this study of the luminescence characteristics of griseofulvin we report corrected ambient temperature fluorescence excitation and emission spectra. The uncorrected fluorescence excitation and emission spectra on thin layer chromatographic plates are also reported. The quantum efficiency of fluorescence is calculated to be 0.108 and the mean phosphorescence lifetime determined to be 0.11 sec. The fluorescence lifetime is calculated to be 0.663 nsec. It appears t h a t phosphorescence emission may be the most sensitive spectral parameter; measurable phosphorescence can be obtained from solutions as dilute as 10-8M. No photodecomposition is apparent under reasonable conditions of light exposure.

Spectroanalytical Parameters of Fungal Metabolites. IV. Moniliformin

1974 ◽  
Vol 57 (6) ◽  
pp. 1392-1396 ◽  
Author(s):  
J A Lansden ◽  
R J Clarkson ◽  
W C Neely ◽  
R J Cole ◽  
J W Kirksey
Keyword(s):  
Low Temperature ◽  
Aqueous Solutions ◽  
Ambient Temperature ◽  
Emission Spectrum ◽  
Potassium Salt ◽  
Emission Spectra ◽  
Fungal Metabolites ◽  
Fungal Metabolite ◽  
Fluorescence Excitation ◽  
Phosphorescence Emission

Abstract The spectral data for a novel fungal metabolite, moniliformin (potassium salt of 1-hydroxycyclobut- 1-ene-3,4-dione), are reported. The corrected ambient temperature fluorescence excitation and emission spectra are given and the quantum efficiency is calculated to be 5.32 × 10舓3. The uncorrected low temperature phosphorescence emission spectrum and lifetime are also reported. Other physical data are given to support spectral evidence that the molecule exists as a dimer in aqueous solutions.

On-the-Fly Fluorescence Lifetime Detection of Humic Substances in Capillary Electrophoresis

2003 ◽  
Vol 57 (3) ◽  
pp. 256-265 ◽  
Author(s):  
Joseph D. Hewitt ◽  
Linda B. McGown
Keyword(s):  
Humic Substances ◽  
Fluorescence Lifetime ◽  
Spectral Characteristics ◽  
Emission Spectra ◽  
Fulvic Acids ◽  
Fluorescence Decay ◽  
Fluorescence Excitation ◽  
Lifetime Analysis ◽  
Decay Profile ◽  
Fluorescence Lifetime Detection

On-the-fly fluorescence lifetime detection was investigated as a tool for studying humic substances in capillary zone electrophoresis (CZE). Humic substances are complex, heterogeneous mixtures of natural products that tend to migrate in a single, broad CZE peak. The intrinsic fluorescence lifetime of five humic substances from the International Humic Substances Society (IHSS) was monitored using excitation at 488 or 364 nm to produce intensity-lifetime electropherograms for each of the substances. Each frequency-domain lifetime measurement, collected at sub-second intervals during the CZE run, contains the equivalent of a complete decay profile. Lifetime analysis of each decay profile was used to construct a lifetime-resolved electropherogram for each lifetime component, from which the variation in relative intensity contributions of each lifetime across the broad CZE peak could be determined. Absorption spectra, fluorescence excitation–emission spectra, and lifetime profiles of batch solutions of the samples were determined as well. It was found that, whereas absorption and fluorescence spectral characteristics tended to discriminate between humic acids and fulvic acids, the batch solution lifetime profiles discriminated instead between samples from different sources, regardless of fraction. On-the-fly lifetime detection provided a more detailed view of the fluorescence decay of the samples, including greater resolution of lifetimes for two of the fulvic acids and greater discrimination among samples based on lifetime profiles across the CZE peaks.

Spectroanalytical Parameters of Fungal Metabolites. I. Citrinin

1972 ◽  
Vol 55 (5) ◽  
pp. 1122-1127 ◽  
Author(s):  
W C Neely ◽  
S P Ellis ◽  
N D Davis ◽  
U L Diener
Keyword(s):  
Thermal Decomposition ◽  
Thin Layer ◽  
Spectral Data ◽  
Fluorescence Lifetime ◽  
Limit Of Detection ◽  
Fluorescence Emission ◽  
Linear Functions ◽  
Fungal Metabolites ◽  
Prior Work ◽  
Fungal Metabolite

Abstract The spectral data of the fungal metabolite, citrinin, were investigated and prior work was reviewed. The analytically important concentration ranges for ultraviolet and fluorometric determinations were studied in 3 solvents. The limits of detection were also determined in the solvents as well as on thin layer chromatographic films. CHCl3 was judged to be the best medium for detection and analysis with a limit of detection of 2 × 10−9M. Ultraviolet absorption and fluorescence emission were linear functions of concentration between 1 × 10−6 and 1 × 10−3M and 4 × 10−9 and 2 × 10−5M, respectively. A quantum efficiency of fluorescence of 0.058 and a mean fluorescence lifetime of 1.52 nsec were calculated. Precautions necessary to avoid thermal decomposition and photodegradation of the sample are outlined.

The photochemical reactivity of some benzoylthiophenes. IV. The effect of an adjacent methyl group on the excited state reactivity of 3-benzoylthiophene

1978 ◽  
Vol 56 (15) ◽  
pp. 1970-1984 ◽  
Author(s):  
D. R. Arnold ◽  
C. P. Hadjiantoniou
Keyword(s):  
Hydrogen Abstraction ◽  
Thiophene Ring ◽  
Emission Spectra ◽  
Photochemical Reactions ◽  
Triplet States ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
State Diagrams ◽  
Phosphorescence Emission ◽  
Intramolecular Hydrogen

The electronic absorption and phosphorescence emission spectra and the photochemical reactivity of several methyl-3-benzoylthiophenes (2- and 4-methyl-3-benzoylthiophene (1, 2), 2,5-dimethyl-3-benzoylthiophene (3), and 3-(2-methylbenzoyl)thiophene (4)) have been studied. Partial state diagrams have been constructed. The lowest energy absorption in hexane solution in every case is the carbonyl n → π* transition. The two lowest triplet states of these ketones are close in energy and, in fact, the nature of the emitting triplet (n,π* or π,π*) depends upon the position of methyl substitution and upon the solvent. The photochemical reactions studied include intramolecular hydrogen abstraction (revealed by deuterium exchange in the adjacent methyl group upon irradiation in perdeuteriomethanol solution), photocycloaddition of dimethyl acetylenedicarboxylate to the thiophene ring, and photocycloaddition of isobutylene to the carbonyl group. Generalizations, potentially useful for predicting photochemical reactivity of these and other aromatic ketones are summarized.

Onset of energy equipartition among surface and body waves

2021 ◽  
Vol 477 (2246) ◽  
pp. 20200775
Author(s):  
L. Borcea ◽  
J. Garnier ◽  
K. Sølna
Keyword(s):  
Radiative Transfer ◽  
Thin Layer ◽  
Surface Waves ◽  
Transfer Equation ◽  
Radiative Transfer Equation ◽  
Body Waves ◽  
Homogeneous Layer ◽  
Power Exchange ◽  
Energy Equipartition ◽  
The Mean

We derive a radiative transfer equation that accounts for coupling from surface waves to body waves and the other way around. The model is the acoustic wave equation in a two-dimensional waveguide with reflecting boundary. The waveguide has a thin, weakly randomly heterogeneous layer near the top surface, and a thick homogeneous layer beneath it. There are two types of modes that propagate along the axis of the waveguide: those that are almost trapped in the thin layer, and thus model surface waves, and those that penetrate deep in the waveguide, and thus model body waves. The remaining modes are evanescent waves. We introduce a mathematical theory of mode coupling induced by scattering in the thin layer, and derive a radiative transfer equation which quantifies the mean mode power exchange. We study the solution of this equation in the asymptotic limit of infinite width of the waveguide. The main result is a quantification of the rate of convergence of the mean mode powers toward equipartition.

scholarly journals Sperm metabolism is altered during storage by female insects: evidence from two-photon autofluorescence lifetime measurements in bedbugs

2015 ◽  
Vol 12 (110) ◽  
pp. 20150609 ◽  
Author(s):  
Klaus Reinhardt ◽  
Hans Georg Breunig ◽  
Aisada Uchugonova ◽  
Karsten König
Keyword(s):  
Fluorescence Lifetime ◽  
Sperm Cells ◽  
Fluorescence Lifetime Imaging ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Photon Excitation ◽  
The Common ◽  
The Mean ◽  
The Difference ◽  
Male Genotype

We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius , was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τ m = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τ m = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype.

scholarly journals MEASUREMENT OF SEDIMENT SUSPENSION IN COMBINATIONS OF WAVES AND CURRENTS

1972 ◽  
Vol 1 (13) ◽  
pp. 55
Author(s):  
J. Kirkegarrd Jensen ◽  
Torben Sorenson
Keyword(s):  
Thin Layer ◽  
Concentration Profile ◽  
Field Data ◽  
Concentration Profiles ◽  
Sediment Suspension ◽  
Calculated Concentration ◽  
Waves And Currents ◽  
The Mean ◽  
Mean Concentration ◽  
Good Agreement

The paper describes a procedure for obtaining field data on the mean concentration of sediments in combination of waves and currents outside the breaker zone, as well as some results of such measurements. It is assumed that the current turbulence alone is responsible for the maintenance of the concentration profile above a thin layer close to the bottom, in which pick-up of sediments due to wave agitation takes place. This assumption gives a good agreement between field data and calculated concentration profiles.

scholarly journals Optimization of Advanced Live-Cell Imaging through Red/Near-Infrared Dye Labeling and Fluorescence Lifetime-Based Strategies

2021 ◽  
Vol 22 (20) ◽  
pp. 11092
Author(s):  
Magalie Bénard ◽  
Damien Schapman ◽  
Christophe Chamot ◽  
Fatéméh Dubois ◽  
Guénaëlle Levallet ◽  
...  
Keyword(s):  
Fluorescence Lifetime ◽  
Live Cell Imaging ◽  
Near Infrared ◽  
Cell Imaging ◽  
Light Exposure ◽  
Photon Counting ◽  
Live Cell ◽  
Stimulated Emission ◽  
Plot Analysis ◽  
Phasor Plot

Fluorescence microscopy is essential for a detailed understanding of cellular processes; however, live-cell preservation during imaging is a matter of debate. In this study, we proposed a guide to optimize advanced light microscopy approaches by reducing light exposure through fluorescence lifetime (τ) exploitation of red/near-infrared dyes. Firstly, we characterized key instrumental elements which revealed that red/near-infrared laser lines with an 86x (Numerical Aperture (NA) = 1.2, water immersion) objective allowed high transmission of fluorescence signals, low irradiance and super-resolution. As a combination of two technologies, i.e., vacuum tubes (e.g., photomultiplier) and semiconductor microelectronics (e.g., avalanche photodiode), type S, X and R of hybrid detectors (HyD-S, HyD-X and HyD-R) were particularly adapted for red/near-infrared photon counting and τ separation. Secondly, we tested and compared lifetime-based imaging including coarse τ separation for confocal microscopy, fitting and phasor plot analysis for fluorescence lifetime microscopy (FLIM), and lifetimes weighting for enhanced stimulated emission depletion (STED) nanoscopy, in light of red/near-infrared multiplexing. Mainly, we showed that the choice of appropriate imaging approach may depend on fluorochrome number, together with their spectral/lifetime characteristics and STED compatibility. Photon-counting mode and sensitivity of HyDs together with phasor plot analysis of fluorescence lifetimes enabled the flexible and fast imaging of multi-labeled living H28 cells. Therefore, a combination of red/near-infrared dyes labeling with lifetime-based strategies offers new perspectives for live-cell imaging by enhancing sample preservation through acquisition time and light exposure reduction.

scholarly journals The Photochemical Reactivity of Some Benzoylthiophenes. III. The Effect of an Adjacent Methyl Group on the Excited State Reactivity of 2-Benzoylthiophene

1975 ◽  
Vol 53 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. R. Arnold ◽  
B. M. Clarke Jr.
Keyword(s):  
Excited State ◽  
Carbonyl Group ◽  
Emission Spectra ◽  
Ultraviolet Absorption ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
Partial Energy ◽  
Phosphorescence Emission ◽  
Π State

The ultraviolet absorption and phosphorescence emission spectra of 2-(2-methylbenzoyl) thiophene (1), 2-benzoyl-3-methylthiophene (2), 2-benzoyl-4-methylthiophene (3), and 2-benzoyl-5-methylthiophene (4) are reported and analyzed. Partial energy diagrams are constructed. The lowest triplet is assigned as a π,π* state of the 2-thienoyl chromophore in every case. Photocycloaddition of isobutylene to the carbonyl group was observed with 1 and 2. The oxetanes are thermally unstable; olefins 1-(2-thienyl)-1-(2-methylphenyl)-2-methylpropene (from 1) and 1-phenyl-1-(2-(3-methylthienyl))-2-methylpropene (from 2) were formed and characterized. Irradiation of 1 and 2 in O-deuteromethanol did not lead to incorporation of deuterium; no reaction was observed. These results are discussed in terms of the existing generalizations potentially useful for predicting photochemical reactivity.

scholarly journals Internal structure and rotation of the Sun: First results from the MDI data

1997 ◽  
Vol 181 ◽  
pp. 203-210
Author(s):  
A.G. Kosovichev ◽  
J. Schou ◽  
P.H. Scherrer ◽  
R.S. Bogart ◽  
R.I. Bush ◽  
...  
Keyword(s):  
Thin Layer ◽  
Spectral Lines ◽  
Convective Boundary ◽  
Doppler Imager ◽  
Lower Amplitude ◽  
Oscillation Modes ◽  
First Results ◽  
Sharp Variation ◽  
The Mean ◽  
Initial Results

The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.

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