Evidence of biogenic greigite (ferrimagnetic Fe3S4) in soil

The occurrence of greigite (Fe₃S₄) in soils is reported for the first time. It forms irregularly-shaped aggregations within plant cells in the Gr₂ horizon of a gley soil developed from colluvial material. Greigite was identified by X-ray diffraction and magnetic measurements and was investigated by optical and transmission electron microscopy. Biogenic formation is proposed, based on the elongated shape of single greigite crystals, and sulphur isotope analyses, which showed a depletion in ³⁴S relative to the soil-water sulphate. The cell-edge length of 0.98639±0.00003 nm is significantly smaller than values reported for sedimentary greigite. The mean coherence length of 27 nm agrees with TEM observations and indicates that the single greigite crystals lie in the superparamagnetic region. However, the fine aggregates show magnetically single-domain behaviour. Greigite is the only carrier of a stable magnetic remanence in the soil profile studied.     

Effects of spatial,temporal, and spectral resolutions on the estimation of wheat and barley leaf area index using multi- and hyper-spectral data (case study: Karaj,Iran)

Precision Agriculture - Leaf area index (LAI) is a key parameter for the calculation of crop biophysical and biochemical processes. Therefore, the accurate estimates of LAI has been always of great...     

Evaluation of gallbladder volume and contraction index with three-dimensional ultrasonography in healthy dogs

Three-dimensional (3D) ultrasonography has been shown to be an accurate and appropriate tool for measurement of gallbladder volume in humans. Therefore, we applied this novel technique for the first time to study fasting and postprandial gallbladder volume in 10 healthy dogs and compared the results with those of 2-dimensional (2D) ultrasonography. Fasting gallbladder volumes determined by 3D ultrasonography were significantly higher than corresponding volumes determined by 2D ultrasonography (P<0.01). Additionally, gallbladder volumes were significantly decreased in the postprandial state compared with the fasting state using 3D ultrasonography (P<0.001), but 2D ultrasonography showed no significant difference (P=0.189). The Gallbladder contraction index was higher in 3D ultrasonography than 2D ultrasonography; however, it did not reach statistical significance (P=0.25). In conclusion, 3D ultrasonography was able to measure gallbladder volume in healthy dogs in this study. It is suggested that 3D ultrasonography can be used to accurately estimate gallbladder volume and contractility.