Search results for "Conversion"

Polysulfonate Cappings on Upconversion Nanoparticles Prevent Their Disintegration in Water and Provide Superior Stability in a Highly Acidic Medium

2018

The stability of organic cappings on hexagonal NaYF4:Ln3+ upconversion nanoparticles (UCNPs) is crucial for their luminescence efficiency in aqueous solutions. The capping removal quickens as the acidity of the medium increases. We demonstrate here that polysulfonates, namely poly(2-acrylamido-2-methyl-1-propanesulfonate) (PAMPS) and poly(sodium 4-styrene sulfonate) (PSS), remain anchored to the surface of NaYF4:Yb3+,Er3+/Tm3 UCNPs even at a pH as low as 2 due to strong acidity of the sulfonate anchoring groups (pKa of ca. −3). Bare UCNPs progressively disintegrate into their compositional F–, Na+, Y3+, and Ln3+ ions. Their disintegration is particularly worrying in highly diluted dispersio…

Multicolor upconversion luminescence of GdVO4:Ln3+/Yb3+ (Ln3+ = Ho3+, Er3+, Tm3+, Ho3+/Er3+/Tm3+) nanorods

2016

Lanthanide-doped GdVO4 nanorods that exhibit upconversion emission under 982 nm excitation have been prepared by a facile room-temperature chemical co-precipitation method followed by a subsequent annealing at temperatures of 600 degrees C, 800 degrees C and 1000 degrees C. Multicolor upconversion emission, including white, was achieved by tuning the concentrations of dopant lanthanide ions (Ho3+, Er3+, Tm3+ and Yb3+) in GdVO4. It is found that four GdVO4 samples emit light with the white chromaticity coordinates of (0.326, 0.339), (0.346, 0.343), (0.323, 0327) and (0.342, 0.340) respectively, under a single-wavelength NIR excitation. These coordinates are very close to the standard equal e…

Lanthanide-doped Y3Ga5O12 garnets for nanoheating and nanothermometry in the first biological window

2018

Abstract Absorption and luminescence spectra in the first biological window of Nd3+ single-doped and Er3+-Yb3+ co-doped Y3Ga5O12 nano-garnets have been studied to evaluate their potential use as simultaneous optical nanoheaters and nanothermometers in biomedicine. Nd3+-doped nano-garnets uses the 808 nm laser radiation, resonant with the largest absorption peak of the 4I9/2 → 4F5/2 transition, for both heating the nanoparticle and populating the 4F3/2 emitting level. Changes in the relative intensities of different emission peaks between Stark levels of the 4F3/2 (R1,2)→4I9/2 (Z1-5) transition can be directly related to the temperature of the nano-garnet. On the other hand, the Yb3+/Er3+com…

Hydrogen bond-mediated conjugates involving lanthanide diphthalocyanines and trifluoroacetic acid (Lnpc2@TFA): Structure, photoactivity, and stability

2020

The interaction between lanthanide diphthalocyanine complexes, LnPc2 (Ln = Nd, Sm, Eu, Gd, Yb, Lu

The impact of conversion on the risk of major complication following laparoscopic colonic surgery: an international, multicentre prospective audit.

2018

BACKGROUND: Laparoscopy has now been implemented as a standard of care for elective colonic resection around the world. During the adoption period, studies showed that conversion may be detrimental to patients, with poorer outcomes than both laparoscopic completed or planned open surgery. The primary aim of this study was to determine whether laparoscopic conversion was associated with a higher major complication rate than planned open surgery in contemporary, international practice.METHODS: Combined analysis of the European Society of Coloproctology 2017 and 2015 audits. Patients were included if they underwent elective resection of a colonic segment from the caecum to the rectosigmoid jun…

Experimental characterization of Ruthenium-based Dye Sensitized Solar Cells and study of light-soaking effect impact on performance

2016

In this paper, we present an experimental investigation on the performance of Ruthenium-based Dye Sensitized Solar Cells (DSSCs) at different irradiance levels, incident wavelengths and hours of illumination. In particular, the measurements have been aimed at studying the performance variation due to light soaking effect since this phenomenon has noteworthy practical implications, such as stability tests of DSSCs. Our results show that the short circuit current density, the open circuit voltage and the conversion efficiency η increase with the hours of light soaking. Finally, the observed phenomenon is reversible, and thus the performance decreases again when the cell is kept in the dark.

Pisanie pomiędzy kulturami : twórczość obcojęzyczna pisarek z Europy Środkowej

2015

Harvesting Fluorescence from Efficient Tk -> Sj (j, k > 1) Reverse Intersystem Crossing for ??* Emissive Transition-Metal Complexes

2013

Using a bimetallic Au(I) complex bearing alkynyl-(phenylene)3-diphosphine ligand (A-3), we demonstrate that the fluorescence can be exquisitely harvested upon T1 → Tk (k > 1) excitation followed by Tk → Sj (j, k > 1) intersystem crossing (ISC) back to the S1 state. Upon S0 → S1 355 nm excitation, the S1 → T1 intersystem crossing rate has been determined to be 8.9 × 108 s–1. Subsequently, in a two-step laser pump–probe experiment, following a 355 nm laser excitation, the 532 nm T1 → Tk probing gives the prominent blue 375 nm fluorescence, and this time-dependent pump–probe signal correlates well with the lifetime of the T1 state. Careful examination reveals the efficiency of Tk → Sj (j, k > …

Synthesis of new orthometallated iridium(III) compounds by chemical and electrochemical methods

1987

Abstract Replacement of one phosphine ligand in IrCl 3 (η 2 -PCBr)(η 1 -PCBr) ( 1 ) (PCBr = P( o -BrC 6 F 4 )Ph 2 ), by various P-donor ligands has given compounds of stoichiometry IrCl 3 (η 2 -PCBr)L ( 3 : L = PMePh 2 ; 4 : L = P( p -MeC 6 H 4 ) 3 ; 5 : L = P(OMe) 3 , 6 : L = P(OPh) 3 ). All of these show two irreversible reduction peaks in the range −1.1, −1.3 and ca. −2.0 V. The electrochemical reduction of compound 1 at −1.5 V (at 0°C) leads to a very reactive iridium(I) species, probably IrCl(PCBr) 2 , which undergoes intramolecular orthometallation at room temperature. Three compounds are obtained as the results of this chemical conversion: IrBr 2 (PC)(PCBr) ( 7 ), IrCl 2 (PC)(PCBr) (…

Contexto editorial, cultural y socio-político de la edición príncipe de la «Historia de la doncella Teodor» (Toledo: Pedro Hagenbach, 1500-1501)

2021

The material analysis of the only surviving copy of the editio princeps of the Historia de la doncella Teodor allows us to date it back to the incunabula era and to attribute its printing to Pedro Hagenbach’s workshop. The close relationship amongst Hagenbach’s workshop, the reformist project of Archbishop Cisneros, and the interests of the Catholic Monarchs sets an editorial and cultural context that supports the adaptation of Teodor to the printing press. This work perfectly agreed with the thematic and ideological guidelines for the renewal of Christian customs and values. The forceful religious and intellectual imposition of the young and learned slave, turned into a “fijadalgo” in the …