Real-time monitoring of CdTe quantum dots growth in aqueous solution.

Quantum dots (QDs) are remarkable semiconductor nanoparticles, whose optical properties are strongly size-dependent. Therefore, the real-time monitoring of crystal growth pathway during synthesis gives an excellent opportunity to a smart design of the QDs luminescence. In this work, we present a new approach for monitoring the formation of QDs in aqueous solution up to 90 °C, through in situ luminescence analysis, using CdTe as a model system. This technique allows a detailed examination of the evolution of their light emission. In contrast to in situ absorbance analysis, the in situ luminescence measurements in reflection geometry are particularly advantageous once they are not hindered by the concentration increase of the colloidal suspension. The synthesized particles were additionally characterized using X-ray diffraction analysis, transition electron microscopy, UV-Vis absorption and infrared spectroscopy. The infrared spectra showed that 3-mercaptopropionic acid (MPA)-based thiols are covalently bound on the surface of QDs and microscopy revealed the formation of CdS. Setting a total of 3 h of reaction time, for instance, the QDs synthesized at 70, 80 and 90 °C exhibit emission maxima centered at 550, 600 and 655 nm. The in situ monitoring approach opens doors for a more precise achievement of the desired emission wavelength of QDs.

Thermo-optical characteristics and concentration quenching effects in Nd3+ doped yttrium calcium borate glasses.

In this work we present a comprehensive study of the spectroscopic and thermo-optical properties of a set of samples with composition xNd(2)O(3)-(5-x)Y(2)O(3-)40CaO-55B(2)O(3) (0 ≤ x ≤ 1.0 mol%). Their fluorescence quantum efficiency (η) values were determined using the thermal lens technique and the dependence on the ionic concentration was analyzed in terms of energy transfer processes, based on the Förster-Dexter model of multipolar ion-ion interactions. A maximum η = 0.54 was found to be substantially higher than for yttrium aluminoborate crystals and glasses with comparable Nd(3+) content. As for the thermo-optical properties of yttrium calcium borate, they are comparable to other well-known laser glasses. The obtained energy transfer microparameters and the weak dependence of η on the Nd(3+) concentration with a high optimum Nd(3+) concentration put this system as a strong candidate for photonics applications.

Galactosaemia in a Brazilian population: high incidence and cost-benefit analysis.

OBJECTIVES: To study the incidence of galactosaemia in the state of São Paulo and the benefit/cost (B/C) ratio of the introduction of neonatal screening for galactosaemia, comparing it with a selective approach. METHODS: An enzymatic-colorimetric assay was used for the screening of total galactose (TG) in a sample of 10% of the births in São Paulo in one year and positive cases were confirmed by the activity of galactose-1-phosphate uridyltransferase (GALT). Detected and referred cases were genotyped using enzyme restriction studies for Q188R, N314D and S135L mutations of the GALT gene. The economic analysis was determined by calculating the B/C ratio and by analysis of sensitivity as a function of the incidence of the disease detected and the variation of the interest rate in the economy. RESULTS: 59 953 newborns were screened for TG, with 3 cases of galactosaemia being identified (0.26% false positives), corresponding to a frequency of 1:19 984 liveborns (95% confidence interval: 1:7494 to 1:59 953). One classical case and one Duarte 2 variant referred to as a selective approach were confirmed. With an incidence of 1:19 984, the B/C ratio was 1.04 for the 11.75% interest rate in effect in Brazil, with values already decapitalized. With a maximum possible incidence of 1:7494, the B/C ratio was 2.79. DISCUSSION: There is an economic advantage in introducing neonatal screening for galactosaemia in the national neonatal screening programme. This advantage could increase with a reduction of the current interest rates in the economy.

Resgate consciencial pluriexistencial (laboratório das retrocognições - CEAEC)

Aspectos fisiológicos: descansada, com boa disposição, trajando roupas claras e confortáveis. Aspectos psicológico: abertismo, um pouco de ansiedade, determinação, expectativa, disposição psicológica, motivação um pouco de euforia (AU)