Search results for " counting"
showing 10 items of 98 documents
Anthracene Fluorescence Quenching by a Tetrakis (Ketocarboxamide) Cavitand
2014
Quenching of both fluorescence lifetime and fluorescence intensity of anthracene was investigated in the presence of a newly derived tetrakis (ketocarboxamide) cavitand at various concentrations. Time-correlated single photon counting method was applied for the lifetime measurements. A clear correlation between the fluorescence lifetime of anthracene as a function of cavitand concentration in dimethylformamide solution was observed. The bimolecular collisional quenching constant was derived from the decrease of lifetime. Fluorescence intensity was measured in the emission wavelength region around 400 nm as a result of excitation at 280 nm. Effective quenching was observed in the presence of…
Comparison of the planimetry and point-counting methods for the assessment of the size of the mandible cysts on orthopantomograms
2011
Sahin, Bunyamin/0000-0001-8538-8443 WOS: 000304343300015 PubMed: 22143725 Objective: The purpose of this study is to compare the computer-assisted planimetry and point-counting methods in evaluating the sizes of the mandibular cysts with respect to their agreement and the time required to analyze. Study Design: The surface areas of 46 mandibular cyst lesions on orthopantomograms were estimated using the point-counting and computer-assisted planimetry methods. Three observers evaluated the outlined areas twice, using the point-counting (PC) and computer-assisted planimetry (CAP) methods with an interval of two weeks. In the planimetry technique, digitalized images and ImageJ software were us…
Digital liquid-scintillation counting and effective pulse-shape discrimination with artificial neural networks
2014
Abstract A typical problem in low-level liquid scintillation (LS) counting is the identification of α particles in the presence of a high background of β and γ particles. Especially the occurrence of β-β and β-γ pile-ups may prevent the unambiguous identification of an α signal by commonly used analog electronics. In this case, pulse-shape discrimination (PSD) and pile-up rejection (PUR) units show an insufficient performance. This problem was also observed in own earlier experiments on the chemical behaviour of transactinide elements using the liquid-liquid extraction system SISAK in combination with LS counting. α-particle signals from the decay of the transactinides could not be unambigu…
In situ detection of atomic and molecular iodine using resonance and off-resonance fluorescence by lamp excitation: ROFLEX
2018
17 pags, 11 figs, 4 tabs
Parallel Measurements of in-vivo Skin Autofluorescence Lifetimes and Photobleaching Rates
2015
Experimental methodology for parallel measurements of in-vivo skin autofluorescence (AF) lifetimes and photo-bleaching dynamic has been developed and tested. The AF lifetime decay distributions were periodically collected from fixed tissue area with subsequent detection of the fluorescence intensity decrease dynamic at different time shifts after the pulse excitation. Temporal distributions of skin AF lifetimes and bleaching dynamic were collected and analyzed by means of commercial time-correlated single photon counting system. Details of the equipment and data processing are described as well as some measurement results that confirm the feasibility of the proposed technology.
Low light level in vitro monitoring of cellular and antigen-antibody reactions using a photon detection camera system — New perspectives for clinical…
1990
This article briefly describes the use of a photon counting system (ARGUS-100) in the detection of low levels of light. The ARGUS-100 was used in determining ATP in cell sections from tumor tissues and in measuring a luminescence-enhanced immunoluminometric assay, using ferritin as the analyte, based on the luminol-peroxide-4-iodophenol reaction with peroxidase as the enzyme. The aim is not so much the presentation of data, but rather to show the potentials of the photon counting camera in increasing our knowledge of the cellular and subcellular levels, as well as lowering the detection limits in already sensitive systems, such as immunoassays.
Determination of particle number and brightness using a laser scanning confocal microscope operating in the analog mode
2008
We describe a method to obtain the brightness and number of molecules at each pixel of an image stack obtained with a laser scanning microscope. The method is based on intensity fluctuations due to the diffusion of molecules in a pixel. For a detector operating in the analog mode, the variance must be proportional to the intensity. Once this constant has been calibrated, we use the ratio between the variance and the intensity to derive the particle brightness. Then, from the ratio of the intensity to the brightness we obtain the average number of particles in the pixel. We show that the method works with molecules in solution and that the results are comparable to those obtained with fluctu…
Analysis of linear alkylbenzene samples with a camera-based equipment
2017
Nestemäisiä tuikeaineita hyödyntävät ilmaisimet ovat saaneet jalansijaa neutriinofysiikassa viime vuosikymmeninä. Perinteisiin Cherenkovin ilmaisimiin niiden etu on suurempi hiukkasten vuorovaikutuksesta aiheutuvan valon tuotto. Lisäksi edullisten, suhteellisen ympäristöystävällisten ja optisesti kirkkaiden tuikeaineyhdisteiden (bentseenin alkyylijohdannaiset) saatavuus mahdollistaa yhä suurempien ilmaisimien rakennuksen. Nestemäisten tuikeaineiden ongelmana on kuitenkin niiden taipumus kerätä epäpuhtauksia itseensä ja niiden muutosalttius UV-säteilyn ja korkeiden lämpötilojen vaikutuksesta. Muutokset heikentävät tuikeaineiden valon tuottoa, ja siksi nestemäisten tuikeaineiden puhdistusta j…
Metabolic Imaging in Microregions of Tumors and Normal Tissues With Bioluminescence and Photon Counting
1988
A method has been developed for metabolic imaging on a microscopic level in tumors, tumor spheroids, and normal tissues. The technique makes it possible to determine the spatial distribution of glucose, lactate, and ATP in absolute terms at similar locations within tissues or cell aggregates. The substrate distributions are registered in serial cryostat sections from tissue cryobiopsies or from frozen spheroids with the use of bioluminescence reactions. The light emission is measured directly by a special imaging photon counting system enabling on-line image analysis. The technique has been applied to human breast cancer xenografts, to spheroids originating from a human colon adenocarcinoma…
Experimental results from Al/p-CdTe/Pt X-ray detectors
2013
Recently, Al/CdTe/Pt detectors have been proposed for the development of high resolution X-ray spectrometers. Due to the low leakage currents, these detectors allow high electric fields and the pixellization of anodes with the possibility to realize single charge carrier sensing detectors. In this work, we report on the results of electrical and spectroscopic investigations on CdTe diode detectors with Al/CdTe/Pt electrode configuration (4.1×4.1×0.75 and 4.1×4.1×2 mm3). The detectors are characterized by very low leakage currents in the reverse bias operation: 0.3 nA at 25 °C and 2.4 pA at -25 °C under a bias voltage of -1000 V. The spectroscopic performance of the detectors at both low and…