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A natural occurrence of a silica/clay nanocomposite material was investigated by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). High-resolution images show that this nanocomposite material consists of 5–20 nm thick slabs of smectite and tridymite/cristobalite layers with coincident normals. In spite of the brittle glass-like appearance of the nanocomposite material its colloidal properties are similar to those of pure smectite but partial loss of expansion capacity was detected upon glycerol solvation. The structural relationship between smectite and silica is interpreted based on the smectite structure model of Edelman and Favejee (1940) which supposes reversed tetrahedra in the SiO4 layer of the TOT structure. This structure model explains the presence of silica impurities in bentonites used as raw material and several geological standard montmorillonites.

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A three years (2008, 2009, and 2011) open field experiment was conducted to study the effect of growing methods (organic and conventional) on the tomato yield components (Brix°, carbohydrate, organic acid, lycopene, and total polyphenols). Significantly higher Brix°, carbohydrate-, and lycopene content was found in conventional production. In spite of this, total phenolic content of tomato fruits was significantly higher in organic production. Our experiences show that it is probable, that the techniques used in the cultivation of organic crops — no artificial nutrients — could activate natural defence mechanisms in tomato plants, by increasing content of total polyphenol in the fruits.

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Winter wheat (Triticum aestivum L.) yield samples taken from a consecutive series of crop years representing drought, normal and moist conditions at the Nagygombos experimental site of the Szent István University have been evaluated. The impact of N topdressing and crop year conditions on the performance of protein and wet gluten content were studied.The results suggest that ascending levels of N topdressing, and increased number of applications had a beneficial effect on the protein content, as well as on wet gluten values. Crop year had a significant effect on quality manifestation. The drier the crop year, the better the recorded quality performance. The magnitude of changes was bigger in case of gluten than in that of protein values. There were minor differences between the two varieties examined, especially in their response patterns to nitrogen supply. Dough formation depends mainly on the gliadin/ glutenin ratio, but there is less information on the agronomic and climatic impacts that may cause alterations in that.

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Acta Alimentaria
Authors:
M. Antal
,
A. Regöly-Mérei
,
L. Biró
,
K. Nagy
,
J. Fülöp
,
E. Beretvás
,
E. Gyömörei
,
O. Kis
, and
A. Vámos

This study investigates the nutritional status, life-style practices, serum vitamin D and bone density of adolescents. A total of 326 adolescents, aged between 11 and 14 years, were involved in the present examination: after winter 110 boys and 97 girls (March 2002 and February 2003), and after summer 66 boys and 53 girls (October 2002 and 2003) were investigated. Energy and nutrient intake and life-style practices were assessed. Body mass and height were measured, body mass index was calculated. Serum concentration of 25-hydroxyvitamin D [25(OH)D] was determined. Bone mineral density of calcaneus was measured. Protein intake was higher than the Hungarian RDA. All of the students had vitamin D intake far below the RDA, 33.3% of boys and 43.2% of girls had Ca intake below 70% of RDA, and sodium intake was more than twice higher than the RDA. After winter, 2% of boys and 8% of girls were considered vitamin D deficient and 11% and 19% vitamin D insufficient, respectively. After summer, 24% of boys and 21% of girls had 25(OH)D level over the reference range. The mineral content of bone was insufficient in 12.9% of boys and 10.4% of girls, respectively. The majority of the students had physical activity only in school, incorporated in the timetable.

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