Search results for "Phosphor"
showing 10 items of 1952 documents
Phosphorescent hybrid organic-inorganic light-emitting diodes.
2010
Excitation Energy Transfer in Organic Materials: From Fundamentals to Optoelectronic Devices
2009
In this review, we discuss investigations of electronic excitation energy transfer in conjugated organic materials at the bulk and single molecule level and applications of energy transfer in fluorescent and phosphorescent organic light emitting devices. A brief overview of common descriptions of energy transfer mechanisms is given followed by a discussion of some basic photophysics of conjugated materials including the generation of excited states and their subsequent decay through various channels. In particular, various examples of bimolecular excited state annihilation processes are presented. Energy transfer studies at the single molecule level provide a new tool to study electronic co…
Simulating soil freeze/thaw cycles typical of winter alpine conditions: Implications for N and P availability
2007
Abstract Seasonally snow-covered alpine soils may be subjected to freeze/thaw cycles, particularly during years having little snow and during the late winter and early spring periods. Freeze/thaw cycles can stimulate soil mineralization and could therefore be one factor regulating nitrogen (N) and phosphorus (P) availability and cycling. In this study laboratory incubation experiments using four soils having contrasting properties have been used to characterize the change in N and P forms (microbial and soluble inorganic/organic) that occur after simulated freeze/thaw cycles. Soil samples were collected from locations representing extreme examples of either direct human management (grazed m…
Generation of white LED light by frequency downconversion using a perylene-based dye
2012
A high efficiency white light emitting diode (LED) was fabricated by generation of frequency down-conversion from a GaN/InGaN blue LED. In place of conventional inorganic phosphors, a perylene-based dye was used for colour conversion. The resulting hybrid structure is analysed by focusing on the visual performance of the realised LEDs employing the most relevant photometric parameters of a light source. Preparation of the organic polymer is described as well. The thermal stability of the dye was investigated and a simple structure which avoids colour degradation is proposed.
Carbon–Phosphorus Coupling from C^N Cyclometalated Au III Complexes
2020
Abstract With the aim of exploiting new organometallic species for cross‐coupling reactions, we report here on the AuIII‐mediated Caryl−P bond formation occurring upon reaction of C^N cyclometalated AuIII complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2‐benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5‐triaza‐7‐phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 through C−P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P{1H} NMR and HR‐ESI‐MS analyses combined with DFT calculations. The C−P coupling has been generalized to other C^N cyclometalated Au…
Isolation Of Organophosphorus Pesticides Bacteria Degraders From Agricultural Sicilian Soils.
2009
Pesticides are generally categorized according to their great or low persistence in the environment. Although new biological, chemical, and management technologies are continually being developed to provide more sustainable production alternatives, it is expected that the use of pesticides will continue to be an essential tool in the integrated pest management. Pesticides are biologically active compounds designed to interfere with metabolic processes. Organophosphorus pesticides (OP) pesticides are less persistent than Organochlorine pesticides (OC), they are not without environmental risks, so this justifies the social concern about their level in different kind of matrices like soil, wat…
Gas chromatographic evaluation of pesticide residue contents in nectarines after non-toxic washing treatments
2004
Washing with aqueous solutions of citric acid, ethanol, glycerol, hydrogen peroxide, potassium permanganate, sodium metabisulfite, sodium laurylsulfate (SLS), sodium hypochlorite, and urea is evaluated for pesticide residue reduction in nectarines and compared with simple tap water washing. Residues of pesticides commonly utilized in nectarines (chlorpyrifos, fenarimol, iprodione, malathion, methidathion, myclobutanil, parathion and pirimicarb) are extracted with ethyl acetate and anhydrous sodium sulfate, extract is concentred and analyzed by GC with nitrogen-phosphorus detection. The formation of possible toxic by-products (chlorpyrifos oxon, malaoxon, methidaoxon and paraoxon methyl) is …
Survivin is regulated by interleukin-4 in colon cancer stem cells
2010
Colorectal cancer has provided an important model to test the stem cell hypothesis of cancer origin, which implies that cancer arises as a result of genetic aberrations in stem cells leading to deregulation of the proliferation/differentiation balance. We and others have demonstrated that, similarly to other solid tumors, colon carcinogenesis and progression are dictated by highly apoptosis-resistant stem-like cells. Our data have suggested that protection from apoptosis is achieved by autocrine production of interleukin-4 (IL-4) through up-regulation of anti-apoptotic mediators. In this study, we extend our analysis to another apoptosis inhibitor widely expressed in tumors, namely survivin…
In vitro comparison of root-canal measurements with conventional and digital radiology.
2002
Aim The present study compared the efficacy of digital and conventional radiology for root-canal length measurement. Methodology Seventy extracted teeth with pre-served roots were used. Root-canal length measurements were completed with K-Flexofiles (numbers 08, 10 and 15) with conventional and digital radiography using two systems (radiovisiography and photostimulate storage phosphor). All films and sensors were exposed at projections of 0 degrees and 20 degrees to the mesial. The images obtained were evaluated with and without magnification, and analysed using the Cohen's kappa test. The accuracy of the three systems to determine the root-canal length were evaluated by measuring the dista…
The transcription factor IRF1 dictates the IL-21-dependent anticancer functions of TH9 cells
2014
The TH9 subset of helper T cells was initially shown to contribute to the induction of autoimmune and allergic diseases, but subsequent evidence has suggested that these cells also exert antitumor activities. However, the molecular events that account for their effector properties are elusive. Here we found that the transcription factor IRF1 enhanced the effector function of TH9 cells and dictated their anticancer properties. Under TH9-skewing conditions, interleukin 1β (IL-1β) induced phosphorylation of the transcription factor STAT1 and subsequent expression of IRF1, which bound to the promoters of Il9 and Il21 and enhanced secretion of the cytokines IL-9 and IL-21 from TH9 cells. Further…