Search results for "quench"
showing 10 items of 306 documents
Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation
2022
International audience; In this study, stationary and time-resolvedfluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N = 103) decomposed by a Parallel Factor Analysis (PARAFAC), andfluorescence decays (N = 22), mathematically fitted, using the conventional exponential modeling and the phasor plot representation. Wine PARAFAC component C4 coupledwith its phasor plot g and s values enable the description of malolactic fermentation (MLF) occur…
Jet quenching as a probe of the initial stages in heavy-ion collisions
2019
Jet quenching provides a very flexible variety of observables which are sensitive to different energy- and time-scales of the strongly interacting matter created in heavy-ion collisions. Exploiting this versatility would make jet quenching an excellent chronometer of the yoctosecond structure of the evolution process. Here we show, for the first time, that a combination of jet quenching observables is sensitive to the initial stages of heavy-ion collisions, when the approach to local thermal equilibrium is expected to happen. Specifically, we find that in order to reproduce at the same time the inclusive particle production suppression, $R_{AA}$, and the high-$p_T$ azimuthal asymmetries, $v…
Sensitivities to neutrino electromagnetic properties at the TEXONO experiment
2015
18 pages.- 4 figures.- 1 table
Design and Synthesis of Novel 1,3-Thiazole and 2-Hydrazinyl-1,3-Thiazole Derivatives as Anti-Candida Agents: In Vitro Antifungal Screening, Molecular…
2019
In the context of there being a limited number of clinically approved drugs for the treatment of Candida sp.-based infections, along with the rapid development of resistance to the existing antifungals, two novel series of 4-phenyl-1,3-thiazole and 2-hydrazinyl-4-phenyl-1,3-thiazole derivatives were synthesized and tested in vitro for their anti-Candida potential. Two compounds (7a and 7e) showed promising inhibitory activity against the pathogenic C. albicans strain, exhibiting substantially lower MIC values (7.81 &mu
Solid-Phase Synthesis of Peptide Libraries Combining α-Amino Acids with Inorganic and Organic Chromophores
2009
The synthesis of two series of peptidic chains composed of bis(terpyridine)ruthenium(II) acceptor units and organic chromophores (coumarin, naphthalene, anthracene, fluorene) by stepwise solid-phase peptide synthesis (SPPS) techniques is described. The first series of dyads comprises directly amide linked chromophores, while the second one possesses a glycine spacer between the two chromophores. All dyads were studied by UV/Vis and NMR spectroscopy, steady-state luminescence, luminescence decay and electrochemistry, as well as by DFT calculations. The results of these studies indicate weak electronic coupling of the chromophores in the ground state. Absorption spectra of all dyads are domin…
Fluorescence induction kinetics as a tool to detect a chlororespiratory activity in the prasinophycean alga, Mantoniella squamata
1990
Abstract Pulse-modulated fluorescence measuring systems were used to study the fluorescence induction kinetics of the primitive prasinophycean alga, Mantoniella squamata . DCMU-treated cells show a very strong non-photochemical quenching which is insensitive to uncouplers and can not be attributed to state transitions or photoinhibition. In order to analyze the origin for this quenching, different inhibitors of the photosynthetic electron flow were applied. It was found that DCCD, an inhibitor of the ATP-synthase as well as of the cytochrome- c oxidase, enhances the fluorescence quenching, whereas antimycin A, which blocks the cyclic electron flow around PS I, stimulates it. The effect of b…
Recombination processes in unintentionally doped GaTe single crystals
2002
Emission spectra of GaTe single crystals in the range of 1.90–1.38 eV have been analyzed at different temperatures and excitation intensities by photoluminescence, photoluminescence excitation, and selective photoluminescence. A decrease in band gap energy with an increase in temperature was obtained from the redshift of the free exciton recombination peak. The energy of longitudinal optical phonons was found to be 14±1 meV. A value of 1.796±0.001 eV for the band gap at 10 K was determined, and the bound exciton energy was found to be 18±0.3 meV. The activation energy of the thermal quenching of the main recombination peaks and of the ones relating to the ionization energy of impurities and…
Modulation of the electronic properties of GaN films by surface acoustic waves
2003
We report on the interaction between photogenerated electron-hole pairs and surface acoustic waves (SAW) in GaN films grown on sapphire substrates. The spatial separation of photogenerated carriers by the piezoelectric field of the SAW is evidenced by the quenching of the photoluminescence (PL) intensity. The quenching levels in GaN are significantly smaller than those measured in GaAs under similar conditions. The latter is attributed to the lower exciton ionization efficiency and carrier separation probabilities mediated by the piezoelectric effect. The PL spectra also evidence energy shifts and broadenings of the electronic transitions, which are attributed to the band gap modulation by …
On low-temperature luminescence quenching in Gd3(Ga,Al)5O12:Ce crystals
2019
The work was supported by the ERDF funding in Estonia granted to the Center of Excellence TK141 “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelec-tronics“ (project No. 2014-2020.4.01.15-0011). Partial support of the projects from the Ministry of Education, Youth and Sports of the Czech Republic no. LO1409, LM2015088 and CZ.02.1.01/0.0/0.0/16 013/ 0001406 is also gratefully acknowledged.
Emission Enhancement by Intramolecular Stacking between Heteroleptic Iridium(III) Complex and Flexibly Bridged Aromatic Pendant Group
2019
Phosphorescent iridium(III) complexes suffer from a strong aggregation quenching, limiting their use in solution-processed or crystalline organic light-emitting diodes. Here we report how an intramolecular stacking between a flexibly bridged bulky aromatic pendant group and the core of nonionic heteroleptic complex can be exploited to minimize the negative effects of this drawback. The stacked conformation provides a rigid sterical shielding of the polar molecular surface, improving photoluminescence quantum yield of the complex both in solution and crystalline state.