نتایج جستجو برای: boron
تعداد نتایج: 18025 فیلتر نتایج به سال:
The concentration of boron, an essential micronutrient for plants, presents a narrow range between deficiency and toxicity. In order to provide the boron requirement for plants, and to avoid toxicity problems, boron compounds are mixed with basic fertilizers. Sodium borate pentahydrate was used as a boron source. Ammonium orthophosphates fertilizers with boron were prepared by neutralizing phos...
Young Valencia orange trees were grown for three years in large outdoor sand cultures on complete nutrient solu tions that varied differentially only in the amount of boron. Three rates of boron were applied to single-tree plots. The plots were replicated four times. No difference in tree size resulted from the differential treatments. Rather large differences in the boron content of the leaves...
This paper studies how boron transient enhanced diffusion (TED) and boron thermal diffusion in Si1 Ge are influenced by a high-energy fluorine implant at a dose in the range 5 10 14 cm 2 to 1 10 cm . Secondary ion mass spectroscopy (SIMS) profiles of boron marker layers are presented for different fluorine doses and compared with fluorine SIMS profiles and transmission electron microscopy (TEM)...
The initial austenite grain size of boron microalloyed steel with three different amounts of boron (20, 40, and 60 ppm) was investigated under different heating temperatures (1150, 1100, and 1050 °C), and hot compression tests of samples in a wide range of temperature (900–1100 °C) and strain rate (0.1–10 s−1) were conducted. It was found that the initial austenite grain size increases with inc...
Boron is an important micronutrient for plants. However, boron is also toxic to cells at high concentrations, although the mechanism of this toxicity is not known. This study aimed to evaluate the effect of boron toxicity on Malus domestica pollen tube growth and its possible regulatory pathway. Our results showed that a high concentration of boron inhibited pollen germination and tube growth a...
Saline waters treatment has become increasingly important for drinking water supply in a greater part of the world. However, some serious limitations had recently been discovered during water treatment, among them the boron problem seems to have a critical meaning. According to the WHO regulations (2011), the boron concentration should be reduced to less than 2.4 mg/L for drinking water. The pu...
Using the minima hopping global geometry optimization method on the density functional potential energy surface we show that the energy landscape of boron clusters is glasslike. Larger boron clusters have many structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers. The differences in the p...
The geometry, electronic, and structural properties of an unusually stable boron cage made of 80 boron atoms are studied, using ab initio calculations. The shape of this cluster is very similar to that of the well-known C60 fullerene, but in the B80 case, there is an additional atom in the center of each hexagon. The resulting cage preserves the Ih symmetry, has a relatively large highest occup...
Constant radial diffusion coefficients of boron through southern pine (Pinus spp.) were determined from the total amount of boron diffusing through wood and the amount of boron remaining o n the wood surface after different diffusion periods. The concentration profiles of the treated samples were measured using a slicing technique. Another coefficient representing the effect unexplained by the ...
this study was carried out in order to determine the effects of boron and cold stress on pollen germination of almond hybrids in vitro culture, two different media including the absence and presence of boron (0 mg/l, and 100 mg/l) in 10% sucrose and 1% agar medium at 24°c in dark conditions. the results showed that different treatments had a significant effect on the germination percentage. the...
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