Hongquan Jiang
Qiaofeng Wang
Shiyang Li
Jingshen Li
Qingyuan Wang
Abstract Pr, N, and P tri-doped anatase TiO 2 nanosheets (PrNPTO) were synthesized by a combined sol-gel solvothermal method and characterized by X-ray diffraction, transmission electron microscopy, N 2 adsorption-desorption, X-ray photoelectron spectroscopy, UV-vis absorbance spectroscopy, and photoluminescence spectroscopy. When the Pr-doping concentration was 1.75 wt% and calcination temperature employed was 550 °C, the resulting PrNPTO showed the highest photoactivity towards the degradation of methylene blue under visible and UV light irradiation. PrNPTO also displayed superior photoactivity towards the degradation of 4-chlorophenol under sunlight ( kapp = 3.90 × 10 −2 min −1 ) over the non-doped, single-doped, and co-doped samples, and P25 TiO 2 ( kapp = 1.17 × 10 −2 min −1 ). The high photoactivity of PrNPTO was attributed to the increased UV and visible light absorption properties, reduced recombination of photogenerated carriers, increased surface hydroxyl content, and improved surface textural properties. PrNPTO was highly efficient and stable under simulated sunlight irradiation, which are essential attributes for practical application in environment-related remediation schemes. Graphical Abstract Enhanced photoactivity of PrNPTO is attributed to increased UV and visible light absorption, reduced recombination of photogenerated e − -h + , increased surface hydroxyl content, and improved surface textural properties.
Mazurak, Z.
Czaja, M.
Lisiecki, R.
Gabrys-Pisarska, J.
A P(2)O(5)-CaO-SrO-BaO phosphate glass doped with Tm(3+) and glasses doped with (Tm(3+), Pr(3+)) were used for this study. The photo-luminescence behaviors of Tm(3+) and Pr(3+) in phosphate glass were investigated by absorption, excitation and emission spectroscopy. The energy transfer between Tm(3+) and Pr(3+) in phosphate glasses (which exhibit a variety of transfer efficiencies) was studied. The experimental quantum efficiencies of the luminescence of Tm(3+) rio and (Tm(3+), Pr(3+)) doped phosphate glasses were measured to give eta/eta(0) = 0.447, 0.305, and 0.179 for (0.4 mol% Pr(3+), 1.0 mol% Tm(3+)), (0.8%Pr(3+), 1.0%Tm(3+)) and (1.6 mol% Pr(3+), 1.0 mol% Tm(3+)), respectively. In order to verify the nature of the ion coupling in our phosphate glass system, we applied the Inokuti-Hirayama model. The non-radiative energy transfer rate from Tm(3+) to Pr(3+), transfer efficiencies, and the donor-acceptor distance have been calculated and compared with obtained experimental data. As usual, the efficiency and the probability of energy transfer increase with the concentration of the acceptor. (C) 2010 Elsevier B.V. All rights reserved.
Marziale, Alexander N.
Herdtweck, Eberhardt
Eppinger, Joerg
Schneider, Sven
Palladium(II) aminodiphosphine PNP pincer complexes [PdR(PNP(H)]PF(6) (1(R); R = Cl Me, Ph; PNP(H) = HN(CH(2)CH(2)P(i)Pr(2))(2)) were prepared. Deprotonation with KO(t)Bu affords dialkylamides [PdR(PNP)] (2(R); R = Cl Me, Ph; PNP = (NCH(2)CH(2)P(i)Pr(2))(2)) in high yield which are stable toward beta-H elimination. While AgPF(6) oxidizes the amides, cationic amido complexes [PdL(PNP)]PF(6) (3(L); L = CN(t)Bu, PMe(3)) were obtained upon chloride abstraction from 1(Cl) with TIPF(6). The reaction of amide 2(Cl) with MeOTf results in N-methylation yielding [PdCl(PNP(Me))]OTf (5) quantitatively. N-H acidities of the amino complexes 1(Me) (pK(a) = 24.2(1)) and 1(Ph) (pK(a) = 23.2(1)) were determined in dmso. Complexes 1(Cl), 1(Me), 2(Cl) 2(Me), 3(CNf8u), and 5 were structurally characterized by single crystal X-ray diffraction. The amido complexes feature pyramidal nitrogen atoms in the solid state. The molecular structures, high N-basicity, and reactivity of the amido complexes can be explained with Pd-N(amido) bonding that is characterized by strong N -> Pd sigma-donation and repulsive d(pi)-p(pi) pi-interactions. This interpretation was confirmed by density functional theory (DFT) calculations of 2(Cl).
ABSTRACT This article aims to identify and analyze the teaching of reading and writing activities in two French classes of first year. The idea is to study how the teacher controls and regulates the process of teaching and learning of reading and writing, understanding the process of teaching and learning at two distinct contexts, real and natural. This goal is achieved through a comparative study conducted at two schools located in the metropolitan area of Grenoble, France. The teaching activity is investigated from instrumented observations and the collection of pedagogical documents. The actions of both teachers are characterized in four analysis categories: education code, significant code education, interdisciplinary education and teaching the meaning of read-write. The findings highlight the heterogeneity and the wealth of practices in the first year, giving access to a better understanding of the complexity of the reading-writing teachinglearning process.=09
Pladys, P.
Magagi, J.
Beuché
e, A.
Le Berre, A.
Branger, B.
Bé
tré
mieux, P.
The aetiology of cavitating periventricular leukomalacia (cPVL) involves pre and perinatal factors. Early postnatal dexamethasone has been associated with an increase in cerebral palsy but its role in the development of PVL remains uncertain.
Fi=C3=BAza, Ana Louise de Carvalho
Pinto, Neide Maria de Almeida
Costa, Elenice Rosa
Abstract This study has aimed to analyze gender inequality among professors of Centro de Ci=C3=AAncias Agr=C3=A1rias (CCA =E2=80=93 Agricultural Science Center), Universidade Federal de Vi=C3=A7osa (UFV), to identify the factors that could influence this gender bias. We sought not only to describe gender inequalities in the spaces occupied by men and women in undergraduate and graduate programs of CCA/UFV, but also to understand the mechanisms through which gender differences were perpetuated. To this end, we used the Lattes Curriculum of professors as a source of information for the analysis of the variables that showed different patterns between professors of both sexes who worked in the graduate programs in the field of agricultural science at UFV. The analysis of data on the distribution by sex also in undergraduate courses of CCA aimed to present a comprehensive overview of gender configurations at all academic levels: undergraduate and graduate education, as well as faculty. The big clue that guided the final conclusions of this research was the perception that professors=E2=80=99 original link was related to the guidance standards set by professors in the graduate program.=09