Boron content

Low sulfur and ash levels are required for high GTE, isotropic cokes used for carbon and graphite specialty products. Highly isotropic cokes are also the filler materials for producing graphite for nuclear reactors. The purity, particularly the boron content, is critical in this appHcation. Properties of typical needle and isotropic (regular) cokes are summarized in Table 1. 

Borgehslt, m. boron content, borgen, v.t. borrow (leas often) lend. 

The intensity of the colour of the extract due to ferroin is observed spectrophotometrically and may be related by calibration to the boron content of the sample. 

To construct the calibration curve, run 5-50 mL of the standard boron solution by means of a burette into 100 mL graduated flasks, add 30 mL of dilute sulphuric acid, and make up to volume. These solutions contain 1 — 10 /ig of B per 3 mL. Use 3 mL of each solution and of a boron-free comparison solution and proceed as above. Plot a calibration curve relating absorbance and boron content. 

Calculate the total boron content of the steel (i.e. acid-soluble plus acid-insoluble boron). 

The water wash removes residual boric acid. Elemental analysis of the final product indicated that boron content was less than 0.005%. 

Because of the tendency to form B—B bonds, further substitution in the direction of a higher B P ratio results in boron-pair formation, even if the total boron content is as low as in Cr5PB2 (ordered Cr5B3 type structure see also 6.7.2.2). 

Interaction In the early phases of the work, which showed that the TOF values almost doubled with Increasing boron content, a careful analysis of the overall results did not suggest a carbon-Fe Interaction. 

Atomic emission spectroscopy (AES) studies on these materials show a boron content of approximately 28.8%. Because of the dilution effects of the vinyl/phenyl... 

In cherozems of Serbia, soil boron is in the range of 25-40 mg/kg. The average B content is 30 mg/kg. Boron content increases with salts in arid soils. Saline salts and saline alkali soils contain 40-65 mg/kg total B. 

Moreover, salts in arid soils increase concentrations of boron. In Israeli soils, total B content in saline alluvial soil is in the range of 150-170 mg/kg, four to six times higher than that in alluvial soils (25-40 mg/kg) (Aubert and Pinta, 1977). The soluble boron contents tend to increase with decreases in rainfall. Bioavailable Mo represents an average 2-20% of total Mo. The percentages of bioavailable Mo are higher in arid and semi-arid zones than in humid zones. Bioavailable Mo is 35.8% of the total Mo in soils of Israel and increases to 50-60% in saline alkali soils in India (Aubert and Pinta, 1977). Total Se concentrations in the western United States are higher... 

Figure 14.8 shows how the hardness varies with the boron content of FeB glasses. The variation is nearly linear over the glass forming range. 

An interesting example of the contamination risks which may be caused by a laboratory vessel is that of boron. Determination of very low boron concentrations, involves a prior separation by distillation and subsequent analysis by spectrometry, with a suitable reagent such a curcumin or carminic acid. The use of laboratory vessels made of borosilicate glass (such as Duran or Pyrex) could lead to very large errors in the boron content found. Such errors are caused by sample contamination from the boron present in the glassware. 

The doso-duster containing two carbon atoms, i.e., o-, m- or p-dicarba-doso-dodecaborane C2B10H12, is electronically neutral (see Chapter 3.2). Therefore, the cages are thermally and chemically stable, and extremely hydrophobic. The C2Bio cages are advantageous for boron neutron capture therapy (BNCT) because of their high boron content and ease of chemical transformation. 

It is interesting and possibly significant that the boron content of bones of 33 individuals has been found to vary from 16 to 138 ppm. by weight.70... 

Analysis of the reaction products showed that the boron content was nearly equimolar to the chloride content after reaction with thionyl chloride. About twice this amount of aluminum was retained by the samples, however. Since the presence of unchanged aluminum chloride could not entirely be ruled out, the balance of aluminum versus chloride was established. From the chloride deficit was substracted the number of silanol groups as determined by the thionyl chloride reaction. This difference was ascribed to molecular water. About one molecule of free water was found for each two silanol groups in the temperature range of 100 to 350°. The sample treated with BCI3 contained considerably less... 

Repeated exposure of rats to an aerosol at a concentration of 470mg/m for 10 weeks caused only mild nasal irritation repeated exposure of rats to 77mg/m for 23 weeks resulted in elevated creatinine and boron content of the urine in addition to increased urinary volume. Conjunctivitis resulted when the dust was applied to the eyes of rabbits, probably the result of the exothermic reaction of boron oxide with water to form boric acid topical application of boron oxide dust to the clipped backs of rabbits produced erythema that persisted for 2-3 days. ... 

Elemental composition Na 60.77%, B 28.58%, H 10.65%. Sodium and boron content can be measured by AA or ICP measuremeant. The borohydride should be dissolved cautiously in water for the metal analysis. The compound is treated with ethanol and volume of liberated hydrogen is measured to... 

Weeth, H.J., C.F. Speth, and D.R. Hanks. 1981. Boron content of plasma and urine as indicators of boron intake in cattle. Amer. Jour. Vet. Res. 42 474-477. 

Electrical measnrements of films as a function of boron doping were also reported in this study. The amount of boron in the films varied over only a small range, from 0.01% at very low borane concentrations in solution (a minimum concentration was needed for the deposition to proceed) to 0.02% at a borane concentration in solution of 0.1 M. The resistivity of the films was high in all cases, varying from ca. 20 kO-cm to 0.4 kO-cm with increase in boron content. Mobility and carrier concentration measnrements showed low values of both (maximum... 

Boron, Estimation of. A general procedure has been developed at PicArsn for estimating the boron content of organodecaborane compds. The sample is refluxed in a mixt of perchloric sulfuric acids with a small amt of K dichromate present... 

First, the carrier assignment is discussed using data of the hole-doped crystal. The dHvA frequencies corresponding to the a, Ji, y and 8 branches increase while those of the p branch decrease. This is due to the decrease in the Fermi energy by the hole-doping. In the dHvA specimen of the hole-doped crystal, chemical analysis indicates that the boron content is about 0.2% of the carbon sites, that is, 0.964 X 1020/cm3. Therefore it can be concluded that the a, Ji, y and 8 carriers are holes and the p carriers are electrons. 

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