Search results for "Luminescence"
showing 10 items of 1696 documents
Multivariate standardisation for non-linear calibration range in the chemiluminescence determination of chromium.
2006
Multivariate standardisation is proposed for the successful chemiluminescence determination of chromium based on luminol-hydrogen peroxide reaction. In an extended concentration range, non-linear calibration model is needed. The studied instrumental situations were different detection cells, instruments, assemblies, time and their possible combinations. Chemiluminescence kinetic registers have been transferred using piecewise direct standardisation (PDS) method. The optimisation of transfer parameters has been carried out based on the prediction residual error criteria. Non-linear principal component regression (NL-PCR) and non-linear partial least square regression (NL-PLS) were chosen for…
Optical properties of silver halide fibres: ageing effects
1996
The relation between the structure of fibres extruded from mixed silver halides and their IR optical losses and luminescence properties is studied. The recently established ageing effect of the considerable growth of mean grain size of the fibre's polycrystalline structure (typically from 20 to 1000 nm in two years) is correlated with IR and luminescence measurements. IR spectra measured in the interval show growth of the concentrations of molecular impurities. The luminescence measurements are used for the characterization of the fibre's structure ordering. The luminescence decay kinetics is analysed theoretically in terms of the diffusion-controlled recombination of spatially well-correla…
Aequorin-expressing yeast emits light under electric control
2011
In this study, we show the use of direct external electrical stimulation of a jellyfish luminescent calcium-activated protein, aequorin, expressed in a transgenic yeast strain. Yeast cultures were electrically stimulated through two electrodes coupled to a standard power generator. Even low (1.5. V) electric pulses triggered a rapid light peak and serial light pulses were obtained after electric pulses were applied periodically, suggesting that the system is re-enacted after a short refraction time. These results open up a new scenario, in the very interphase between synthetic biology and cybernetics, in which complex cellular behavior might be subjected to electrical control.
Adenosine monophosphate-capped gold(i) nanoclusters: synthesis and lanthanide ion-induced enhancement of their luminescence
2016
Reduction of Au3+ in the presence of just adenosine 5′-monophosphate (AMP) and a zwitterionic organic chemical buffering agent, specifically 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), combined with light exposure, gives rise to luminescent, water-soluble Au+ nanoclusters (Au+ NCs). The photoluminescence of these NCs is considerably enhanced by adding Y3+ or the chemically similar Yb3+ lanthanide that leads to Au+/Y3+ and Au+/Yb3+ NCs, respectively. These NCs are characterised by absorption (steady-state), photoluminescence (steady-state and time-resolved), and X-ray photoelectron spectroscopy.
Correlation of the chemiluminescence-activity of peripheral blood monocytes with CSF parameters of inflammation and the clinical course of patients w…
2009
– The chemiluminescence-activity (CL-A) of peripheral blood monocytes (MO) was measured in eight patients with lymphocytic meningitis or meningoencephalitis and compared to CSF parameters and the clinical course. The initial maximum CL-A was around four times above the control and decreased to normal values within approximately 20 days. Poor correlations were found when the CL-A was compared to CSF parameters in the total group of patients. With regard to the CSF parameters in individual patients the CL-A was closely related to the cell count, to a lesser degree to the protein content, but not to the IgG content. Finally, a very good correlation of the CL-A was found with the clinical cours…
Reference interval determination for N-terminal-B-type natriuretic peptide (NT-proBNP): A study in blood donors
2005
We assessed reference values in a group of apparently healthy blood donors. A total of 1980 blood donors was recruited and tested for the presence of NT-proBNP using a newly developed electrochemiluminescence immunoassay (ECLIA) method. NT-proBNP clustered in all blood donors below the age of 50 years and an upper limit of normal (ULN) was found to be 84 pg/ml for males and 146 pg/ml for females. Mean NT-proBNP values increased with increasing age which was due to an increasing number of individuals exceeding the ULN. Age- and gender-appropriate NT-proBNP levels decreased with increasing hemoglobin levels. Hemoglobin but not creatinine levels influenced the NT-proBNP concentration in this c…
The behaviour of OKT3-, OKT4- and OKT8-positive cells during phases of elevated spontaneous chemiluminescence activity (CL-A) in multiple sclerosis p…
1987
The chemiluminescence activity (CL-A; synonym = burst activity, BA) and the percentage of OKT3-, OKT4- and OKT8-positive peripheral blood cells were serially examined in four control persons and in eight patients with multiple sclerosis. When the OKT values obtained in phases of increased CL-A (clinical remission) were compared with those of the control group, the percentage of OKT3-positive cells was reduced (P = 0.014), and that of OKT4-positive cells increased (P = 0.014); there were no significant changes in the percentage of OKT8-positive cells (P = 0.171). After the CL-A had returned to normal values, the OKT4-positive cells remained elevated (P = 0.029), whereas the OKT3- (P = 0.342)…
Supramolecular systems based on gold(I) derivatives : molecular recognition of L-glutamine and polyQ
2017
L-glutamiinin ja polyglutamiinin molekyylintunnistuksessa käytettyjen uusien organometallikompleksien mielenkiintoiset luminesoivat ominaisuudet ovat peräisin 4-etynyylianiliiniligandista ja fosfaaniyksiköstä sekä molekyylien välisistä Au⋯Au vuorovaikutuksista. Heikkojen intermolekulaaristen vuorovaikutusten on havaittu johtavan kuitu- ja pallomaisten muotojen morfologisiin muutoksiin vierasmolekyylien läsnä ollessa. Muodostunut isäntä-vieras -kompleksi tuottaa erilaisen emission vierasmolekyylistä riippuen. Lisäksi [Au(4-etynyylianiliini)(PTA)]:n itsejärjestäytymisen termodynaamisia funktioita tutkittiin eri pitoisuuksissa ja lämpötiloissa NMR mittausten avulla. Nämä lineaariset kulta(I) -…
Luminescence of silica glass containing aluminum oxide
2004
Abstract Optical properties of silica glass with different doping of Al 2 O 3 up to 1.5 mol% were studied. Alumina stimulates creation of a luminescence centers with specific band at 3.3 eV. A new band at 8.2 eV appears in luminescence excitation spectra. There is transport of energy to other luminescence centers associated with an impurity (Ag, Ce) at this energy. Alumina stimulates creation of E′ centers under γ-irradiation beside trapped hole on AlO 4 tetrahedron as well as creation of a silicon related oxygen deficient center (SiODC) under cathodoexcitation. Visually, the samples look inhomogeneous even after γ-irradiation. The explanation could be heterogeneity of the samples. Alumina …
Thermostimulated processes in statically and dynamically disordered luminescent solids
1993
Abstract Trap spectra depending on the concentration of defects in crystalline KBr-T1, LiF-Mg, Ti, A1 2 O 3 and glassy Na 2 O·SiO 2 are investigated. The nature of inhomogeneous broadening and continuous distribution of traps over activation energies at sufficiently high defect concentrations is considered. Impurity hopping controlled recombination of electronic excitations is observed. The presence of enlarged values of process activation energies and frequency factors is discussed in terms of the concept of dynamic disorder, taking into account the fluctuational changes in both the perfectpart and the structure of defects in the solid at high temperatures.