Development and Validation of a Food Frequency Questionnaire for Preschool Children Using Multiple Methods

Background: The ability to determine the relationship between diet and health outcomes in children requires reproducible and validated long-term dietary assessment tools such as food frequency questionnaire (FFQ).Objective: To test the reproducibility and relative validity of a FFQ for young children using 24-hour food recalls (24HRs), anthropometric measurements, and a comprehensive feeding practices questionnaire (CFPQ).Methods: Children (aged 5-6) and their mothers were recruited during one school-year (2008) from preschools. Children's anthropometric measurements were obtained. Mothers provided during a personal interview on three occasions a 110-item semiquantitative FFQ, 24HRs and CFPQ. Pearson-correlation coefficients were calculated between the results of the FFQ and 3*24HR. Validity coefficients between the FFQ and the different measurements were calculated. Scores of the 12 factors of the CFPQ were calculated and related to dietary intake.Results: Sixty-six healthy children (47% boys) were recruited. Pearson's correlations between the average of the FFQs and 3*24HRs ranged from 0.3-0.6 (P<0.05). The highest correlation coefficients were 0.59 for total fat intake and 0.56 for energy. Dietary intake of energy and carbohydrates differed significantly (P=0.05, 0.001 respectively) across the three BMI z-score levels (normal-weight, overweight, obese) and the three waist circumference tertiles (0.019, 0.006 respectively). Obesogenic factors from the CFPQ correlated with consumption of empty calories like sweets, snacks, junk foods and sweet drinks.Conclusions: The modified FFQ is a relatively valid instrument to estimate mean energy intake in preschool children. The questionnaire performs reasonably well to rank children with respect to macronutrients intake as well as obesogenic food groups

Nanocrystalline Pbte Films

This work deals with the impact of nano-scale morphology on the photoelectric properties of n-type PbTe thin films. Nano-structured thin films were prepared by varying the rate of nucleation as a function of the nature and the temperature of the substrates. The broken bonds at the grain boundaries generate acceptor states in n-type films, capture electrons from the interior of the grains and give rise to p-type inversion layers between adjacent grains. A model based on the assumption that the current is exclusively due to the motion of holes in the inversion channels along the grain boundaries, is proposed to explain the temperature dependence of photoelectric properties. This approach allows designing infra-red detectors based on nano-crystalline lead chalcogenide films at the wavelength up to 4-5 μm that don\u27t require cryogenic cooling. Copyright © 2009 American Scientific Publishers All rights reserved

Synthesis and Characterization of WS2 Inorganic Nanotubes with Encapsulated/Intercalated CsI

WS2 nanotubes have been filled and intercalated by molten phase caesium iodide. The presence of caesium iodide inside the WS2 nanotubes has been determined using high-resolution transmission electron microscopy (HRTEM) coupled with electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS). Noticeably, a Moiré pattern was observed due to the interference between encapsulated CsI and WS2 layers. The intercalation of CsI into the host concentric WS2 lattices resulted in an increase in the interplanar spacing.close7

Photoconductivity of PbTe:In films with variable microstructure

It is shown that the microstructure and features of formation of surface states in nanocrystalline and polycrystalline PbTe:In films most significantly affect the character of photoconductivity in the spectral range of 1–2.5 THz. We present the results of a study and comparative analysis of the character of conductivity of PbTe:In films in the temperature range from 4.2 to 300 K in a static mode and in variable electric fields with a frequency of up to 1 MHz with illumination with white light and under the effect of high-power terahertz laser pulses with a wavelength of up to 280 μm