Search results for "mines"

<title>Spatial correlation of latent image centers active in photostimulable luminescence of irradiated doped alkali halides</title>

2001

Changes in the photostimulated luminescence (PSL) spectrum of an electron irradiated KBr:Tl single crystal in relation to the A-luminescence spectrum upon direct activator ion excitation in the A-absorption band (AL) are found. Based on the view about the spatial correlation between F and activator hole centers, it is suggested that anion vacancy is an additional perturbing factor fot he activator (Tl+) excited (p-electron) state which is already subject to the dynamical Jahn-Teller effect. Dependences of the PSL efficiency on activator (In+) concentration in KBr:In samples irradiated by UV-light (6.30-6.45 eV), X-rays (30 keV or electrons (5.6 keV), are compared. The possible role of 6.45 …

The use of X-ray-induced and thermostimulated visible and UV luminescence for understanding X-ray poling of silica glasses

2007

In this paper, we studied the X-ray-induced visible and UV luminescence (XRL) during X-ray irradiation, afterglow (after X-ray was switched off) and thermostimulated luminescence (TSL). Comparisons were performed between with and without applying an electric field of 1.5 kV/mm on the sample. The typical TSL curve for X-ray-irradiated samples present two peaks centered at 90 and 280 °C. The relative intensity of these two peaks is X-ray dose dependent. An external electric field enhances the XRL, but has no effect on the afterglow. The TSL and afterglow spectra are identical with one peak at 3.25 eV, whereas XRL spectrum displays an additional peak at 4.25 eV. A model of electron exchange be…

ChemInform Abstract: Synthesis, Luminescence, and Condensation of Oligo(phenylenevinylene)s with Alkoxysilane End Groups

2009

Time-resolved luminescence and induced absorption in PbWO4

1997

Abstract Luminescence and short-lived induced absorption are studied for two undoped PbWO4 crystals. Luminescence decay at LNT is delayed relative to irradiation pulse. The delay observed is either due to reabsorption of luminescence or due to creation of luminescence center excited states via energy or/and charge transfer after irradiation pulse. Short-lived absorption is observed within 1.1–3.6 eV spectral region at LNT as well as at RT. It is proposed that the short-lived absorption band peaking at ~ 3.5 eV is intrinsic.

Selective, Sensitive, and Rapid Analysis with Lateral-Flow Assays Based on Antibody-Gated Dye-Delivery Systems: The Example of Triacetone Triperoxide

2013

[EN] Antibodygated MSNs that are loaded with a rhodamine dye and that can be used for the determination of the presence of peroxide-based explosive TATP with a lateral-flow fluorescence reader have been designed and prepared, thereby allowing for detection limits in the lower ppb range. The mechanism of the detection relies on a displacement of the antibody from the surface of the hybrid material because of highly affine antibody-TATP interactions, which release a much larger number of entrapped dye molecules from the pores than antibodies are displaced. The high selectivity of the antibody is retained in the gated material, thus allowing for a remarkable discrimination against H2O2. System…

<title>Spectroscopic investigation of the nicotinic acetylcholine receptor for application in medical diagnosis</title>

1998

Native vesicles containing the nicotinic acetylcholine receptor (nAChR) prepared from the electric organ of the ray Torpedo marmorata were used to obtain fluorescence signal sin dependence of different concentrations of the local anesthetics procaine. Nonlinear concentration dependent spectral changes are found using ethidium bromide as a fluorescence marker. Structural changes are found for the proteins including the nAChR in the vesicles during immobilization onto surfaces such as IR transparent germanium (GE) crystal, Ge crystal coated with silver (Ag) cluster to use the SEIRA effect and/or crystals covered with a lipid subphase. A comparison between Ge and Ge coated with Ag (Ge/Ag) clus…

Dual-emitting Langmuir-Blodgett film-based organic light-emitting diodes.

2010

Langmuir-Blodgett (LB) films containing alternating layers of the metallosurfactants bis(4,4'-tridecyl-2,2'-bipyridine)-(4,4'-dicarboxy-2,2'-bipyridine) ruthenium(II)-bis(chloride) (1) and bis[2-(2,4-difluorophenyl)pyridine](4,4'-dinonadecyl-2,2'-bipyridine)iridium(III) chloride (2) have been prepared. Langmuir monolayers at the air-water interface of 1 and 2 with different anions in the subphase have been characterized by pi-A compression isotherms and Brewster angle microscopy (BAM). The transferred LB films have been characterized by IR, UV-vis and emission spectroscopy, and atomic force microscopy (AFM). Electroluminescent devices formed by LB films containing alternating layers of thes…

Detection and characterization of emerging psychoactive substances by ion mobility spectrometry

2014

Rapid detection and identification of novel psychoactive substances (NPS) continues to present significant analytical challenges to forensic and analytical chemists. Ion mobility spectrometry (IMS) has been traditionally considered as the analytical technique of choice to detect illicit drugs in security points in airports, borderlines and customs. Databases of the reduced mobility (K0 ) values of illicit drugs are available in the scientific literature and they should be completed with data of emerging designer drugs. In this paper, we have evaluated the effect of different measurement conditions and determined the K0 values of an important number of NPS including different families; such …

Inhibitory effects of N-acetylcysteine on the functional responses of human eosinophils in vitro

2007

Background Oxidative stress appears to be relevant in the pathogenesis of inflammation in allergic diseases like bronchial asthma. Eosinophils are oxidant-sensitive cells considered as key effectors in allergic inflammation. Objective The aim of this work was to study the effects of the clinically used antioxidant N-acetyl-L-cysteine (NAC) on the functional responses of human-isolated eosinophils. Methods Human eosinophils were purified from the blood of healthy donors by a magnetic bead separation system. The effects of NAC were investigated on the generation of reactive oxygen species (chemiluminescence and flow cytometry), Ca2+ signal (fluorimetry), intracellular glutathione (GSH; flow c…

Solution-, solid-phase, and fluorous synthesis of beta,beta-difluorinated cyclic quaternary alpha-amino acid derivatives: a comparative study.

2008

The diastereoselective synthesis of cyclic beta,beta-difluorinated alpha-amino acid derivatives bearing a quaternary stereocenter is described. The process relies on the chemo- and diastereoselective addition of allylic organometallic reagents to fluorinated alpha-imino esters and a subsequent ring-closing metathesis reaction (RCM). Complete selectivity in the nucleophilic addition was achieved with (R)-phenylglycinol methyl ether as a chiral auxiliary. The resulting amino acids were introduced into peptide chains, which could facilitate the preparation of potentially bioactive dipeptide derivatives. In addition, the solution synthesis of these cyclic fluorinated alpha-amino acids was succe…