Search results for "conversion"

Up-conversion processes in NaLaF4:Er3+

2009

abstract Structural and spectroscopic investigation of NaLaF 4 :Er 3+ material at different doping concentrations ispresented. X-ray diffraction patterns, up-conversion luminescence spectra and decay curves for 2 H 9/2 ? 4 I 15/2 , 4 S 3/2 ? 4 I 15/2 and 4 F 9/2 ? 4 I 15/2 optical transitions in the material are shown and possibleexcitation routes are discussed. Raman spectrum for the undoped material is presented and the effectivephonon energy of the material is estimated. Based on the obtained results application of rare-earth dopedNaLaF 4 in the field of up-conversion phosphors is evaluated. 2009 Elsevier B.V. All rights reserved. 1. IntroductionFor many years rare-earth (RE) doped materi…

Ab initio modeling of excitonic and charge-transfer states in organic semiconductors: the PTB1/PCBM low band gap system.

2013

A detailed quantum chemical simulation of the excitonic and charge-transfer (CT) states of a bulk heterojunction model containing poly(thieno[3,4-b]thiophene benzodithiophene) (PTB1)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is reported. The largest molecular model contains two stacked PTB1 trimer chains interacting with C60 positioned on top of and lateral to the (PTB1)3 stack. The calculations were performed using the algebraic diagrammatic construction method to second order (ADC(2)). One main result of the calculations is that the CT states are located below the bright inter-chain excitonic state, directly accessible via internal conversion processes. The other important aspects…

CONVERSIONE CHEMO-ENZIMATICA DI GLUCOSIO IN 5-HMF IN MISCELE IL/H2O, PROMOSSA DA ESTRATTO CELLULARE BATTERICO E ULTRASUONI

742 EFFICACY AND SAFETY OF ENTECAVIR (ETV) PROPHYLAXIS IN INACTIVE HBV CARRIERS WHO UNDERWENT CHEMOTHERAPY FOR SOLID OR HAEMATOLOGICAL CANCER: INTERI…

2013

seroconversion rate at 48 weeks were 40.7% and 37% in PEG-IFN a-2a group, respectively, which are both higher than those in ETV group (16.7% and 13.3%, P all 0.05). The mean qHBsAg level in PEG-IFN a-2a group declined over time during treatment. The qHBsAg level at 48 weeks was significantly lower than that in ETV group ((2866.0±2580.4) vs (4335.8±2650.0) IU/mL, P = 0.027). A greater HBsAg decline was observed in HBeAg seroconverters compared with nonseroconverters. The decline from baseline was significantly different between seroconverters and non-seroconverters especially at 36 weeks ((1763.4±3116.2) vs (1333.5±2483.4) IU/mL, P = 0.036), and 48 weeks (1979.6±2897.1) vs (1631.8±2395.8) IU…

Speciation of Cr in Leachates of a MSWI Bottom Ash Landfill

1998

Cr concentrations and speciation were determined in leachate from a municipal solid waste incinerator bottom ash landfill both experimentally and by thermodynamic model calculations. Total dissolved Cr concentrations of 0.2 mmol L-1 were determined by GFAAS. Two orders of magnitude lower values were determined upon preconcentration by an in-situ solid-phase extraction technique based on the 8-HQ cation exchanger that is specific for Cr(III) but unspecific for Cr(VI). This suggests that chromate dominates the dissolved Cr concentrations in the leachates but was up to 5 orders of magnitude undersaturated with respect to the solubility of CaCrO4 or BaCrO4. Chromate adsorption by oxyhydroxides …

An ESCA and Mössbauer study of the oxide layer formed on steel in water containing chromate and chloride ions

1983

Abstract The formation of oxidic layers on steel in chromate solutions was studied by photo-electron and Mossbauer spectroscopy. To simulate more aggressive realistic systems, some chloride ions were added to the solution. The layers formed under these conditions were found to be thicker by an order of magnitude than those formed in the absence of chloride ions. They probably consist of ferric and chromic oxides of the corundum type (Fe 1−2 Cr x ) 2 O 3 , with the Cr : Fe ratio being depth dependent. The oxide layer is subdivided into small regions behaving superparamagnetically. This heterogeneity of the layer is ascribed to the attack by the chloride ions. The structure of the oxides foun…

Cr(VI) sorption by intact and dehydrated Candida utilis cells in the presence of other metals

2002

This study examined the Cr(VI), Cu(II), Zn(II), Cd(II), Pb(II) sorption by intact and dehydrated Candida utilis cells. The anion [Cr2O7]2− and cation Me2+ sorption kinetics was investigated in both single- and dual-metal situations. Uptake of chromate anions occurred much more slowly singularly than with metal cations. A combination of Pb or Cu and chromate anions gave a synergistic effect for Cr(VI) sorption, but not Cd and Zn, which inhibited Cr(VI) sorption by dehydrated cells. The use of alcian blue to occupy maximum vacant adsorption sites on the cell surface unexpectedly did not influence further adsorption of Me2+. Metal uptake by C. utilis was 7 mg (135 μM) Cr, 23 mg (362 μM) Cu, 39…

Theoretical Insights into the Ferromagnetic Coupling in Oxalato-Bridged Chromium(III)-Cobalt(II) and Chromium(III)-Manganese(II) Dinuclear Complexes …

2012

Two novel heterobimetallic complexes of formula [Cr(bpy)(ox)(2)Co(Me(2)phen)(H(2)O)(2)][Cr(bpy)(ox)(2)]·4H(2)O (1) and [Cr(phen)(ox)(2)Mn(phen)(H(2)O)(2)][Cr(phen)(ox)(2)]·H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and Me(2)phen = 2,9-dimethyl-1,10-phenanthroline) have been obtained through the "complex-as-ligand/complex-as-metal" strategy by using Ph(4)P[CrL(ox)(2)]·H(2)O (L = bpy and phen) and [ML'(H(2)O)(4)](NO(3))(2) (M = Co and Mn; L' = phen and Me(2)phen) as precursors. The X-ray crystal structures of 1 and 2 consist of bis(oxalato)chromate(III) mononuclear anions, [Cr(III)L(ox)(2)](-), and oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) din…

Sodium Congener of the Classical Lithium Methylchromate Dimer: Synthetic, X-ray Crystallographic, and Magnetic Studies of Me8Cr2[Na(OEt2)]4

2011

One of the milestone structures in the development of transition-metal complexes with metal metal bonds of multiple bond order was the lithium methylchromate dimer Me8Cr2[Li(donor)](4) (donor = THF or Et2O). Using a simple salt metathesis reaction mixing this compound with sodium tert-butoxide, the sodium congener Me8Cr2-[Na(OEt2)]4 has been synthesized as a green crystalline compound and isolated in 51% yield. Its solid-state structure was determined by single-crystal X-ray diffraction. Exhibiting exact crystallographic C-4h symmetry, this heavier alkali-metal chromate structure is also dimeric, formally comprising a (Me8Cr4)(4-) tetranionic core with four peripheral Na+ cations carrying s…

Modeling of continuous Ph-stat stirred tank reactor withLactococcus lactisssp.lactisbv.diacetylactisimmobilized in calcium alginate gel beads

1995

A dynamic diffusion-reaction-growth model is proposed for the study of lactic fermentation, the bioconversion of citric acid, and cell release in an immobilized cell reactor [pH-stat continuous stirred tank-reactor (CSTR)]. The model correctly simulates the onset of fermentation and colonization of the gel, followed by the steady state. External diffusion is nonlimiting and internal diffusion is limited by high cell densities at the periphery of the gel beads. Lactose-citrate cometabolism in the gel is related to the distribution of active included biomass within the gel and to gradients of substrates (lactose, citrate) and products (lactate, pH) in the beads. The utilization of lactose is …