Boron Absorption Research Articles

The chronic exposure of selected crop species to boron aerosols

Reports of damage on vegetation around several point sources have indicated boron is a phytotoxic air pollutant. This study compared the effect of chronic foliar aerosol exposures (0, 1.55 or 3.09 μg B/cm 2 leaf area, three times per week) on five crop species varying in their leaf-type and sensitivity to boron via root exposure. Foliar absorption of boron was not determined by leaf-type and was fairly uniform across species. Phytotoxicity occurred in species according to the quantity of boron accumulating in their leaves and was correlated to the sensitivity of the species to root boron exposure. In a separate study, chronic foliar aerosol exposures were given to plants grown in hydroponic solutions with a range in boron concentration from deficiency to toxicity. Visual damage identical to that of root boron toxicity was observed on all plants, including those grown at deficient solution levels.

Plant availability of applied and native boron in soils with diverse properties

Laboratory and greenhouse research was conducted to study effects of soil properties on the availability of native and applied B in 14 Virginia soils. Boron absorption could be described by the Langmuir equation in 12 of the 14 soils, and maximum B adsorption (Vmax) in these 12 soils ranged from 3.3 to 26.5 mg kg−1. A multiple regression equation, −19.3+3.51 pH+0.048 clay content, accounted for 89.6% of the variation in Vmax for the 12 soils. Curvilinear relationships (α=0.01) occurred between B in corn (Zea mays L.) tissue from native B and hot-water soluble B, mannitol exchangeable B, and NH4-acetate and Mehlich III extractable B. Among these four procedures, mannitol exchangeable B correlated most closely (r=0.923) with B in corn tissue from native B. From 0.4 to 13.5% of the applied B was absorbed by corn plants and translocated to shoots. Curvilinear relationships (α=0.01) occurred between B in corn tissue from applied B and soil clay content, NH4-oxalate extractable Al and Fe, and acidified NH2OH·HCl extractable Mn. It is evident from these relationships that soil clay and oxyhydroxides of Al, Fe, and Mn have an affinity to adsorb B in somewhat unavailable forms.

Absorption of boron after mouthwash treatment with Bocosept.

Healthy volunteers and patients with gingivitis were treated locally with the boron-containing bacteriostatic agent, Bocosept. Blood levels and urinary excretion of boron were examined by a spectrophotometric method. Blood concentrations after a single mouthwash with Bocosept slightly exceeded those after intake of 200 g raisins or a bottle of red wine. The blood levels during a one-week course of treatment showed a low rate of boron accumulation. The highest concentration was about 0.3 microgram B/ml, a level which does not seem to involve any risk of boron poisoning. The small amount taken up after mouthwash treatment with Bocosept does not appear to represent absorption by the oral mucosa. It seems more likely that the uptake of boron takes place in the intestine after ingestion of residual amounts from the mouth.

Low‐frequency sound attenuation in the Labrador Sea‐Baffin Bay region

A series of long range propagation runs were analyzed to determine attenuation coefficients for the frequency range 25–1000 Hz. Above 200 Hz, the dominant cause of attenuation was boron absorption; below 200 Hz, the attenuation was independent of frequency indicating a scattering mechanism as the cause. In the Labrador Basin, absorption was close to that predicted by the Thorp formula; in the Davis Strait and Baffin Bay, it was significantly higher (1.3–1.5 Thorp). This increase, corresponding to higher pH values, can be attributed to two possible causes, the influence of the oxygen‐rich Labrador current and the higher pH values encountered as the sound channel axis shallows. The frequency independent component was similar in the Labrador Sea and Davis Strait but lower in Baffin Bay confirming results reported earlier [R. H. Mellen et al., J. Acoust. Soc. Am. 57, 1201–1202(L) (1975)] and suggesting less scattering in Baffin Bay. (Work supported by NUSC)

A model for ferrite nucleation applied to boron hardenability

A model for the nucleation of ferrite on austenite grain boundaries proposed by Sharma and Purdy is reexamined using the Cahn-Hoffman construction. The construction, which offers a rigorous method of predicting the shape of heterogeneous nuclei, indicates that the original proposal of a disk shaped nucleus should be modified to that of a spherical segment. Based on currently available thermodynamic and physical data, it is shown that the spherical segment model is very sensitive to the austenite grain boundary interfacial tension. Even small changes in interfacial tension of several mN/m, which could result from the equilibrium absorption of boron into austenite boundaries, is sufficient to delay the austenite transformation by a significant time.

Low‐frequency attenuation in the Pacific Ocean

There is increasing evidence that the low‐frequency sound absorption in the Pacific is less than that in the Atlantic. The origin of the excess absorption below 1 kHz has recently been identified as a boron relaxation. A compilation of available Pacific data appears to show one‐half the boron absorption found in the Atlantic, which suggests significant differences in the chemical composition of the oceans.

Optical and Electrical Properties of Boron

Optical constants of β-rhombohedral and amorphous boron were obtained by ellipsometry and by the measurements of transmissivity and reflectivity. The values of the refractive index were found between 3.00 and 3.35 for wavelengths between 0.35 µm and 1.20 µm. Absorption coefficient α of amorphous boron as a function of the photon energy \\hbarω was found to follow the equation α=B(\\hbarω-E0)2/\\hbarω and constants E0 and B were 1.00 eV and 1.7∼2.1×105 cm-1·eV-1 respectively. High temperature conductivity σ of amorphous boron was expressed in the form σ=C exp (-E/kT) and 2E and C were 1.04∼1.16 eV and 7∼12×103 ohm-1·cm-1 respectively. Absorption of β-rhombohedral boron was considered to be caused by indirect transitions from valence band to conduction band. From the temperature dependence of conductivity, the energy gap between valence band and conduction band was estimated to be 1.34 eV for β-rhombohedral boron.

Low-frequency attenuation in the Pacific Ocean

There is increasing evidence that the low-frequency sound absorption in the Pacific is less than that in the Atlantic. Thorp's original empirical equation was based largely on North Atlantic data. The origin of his excess attenuation anomaly has recently been identified as a boron relaxation. A compilation of available Pacific data appears to show roughly one-half the boron absorption predicted by Thorp, which suggests differences in the chemistry of the oceans.

Application, Absorption and Translocation of Boron in Oil Palm. III. Leaf Analysis for Diagnosing Boron Requirements

SUMMARYA method is described for estimating boron requirements of the oil palm, and factors influencing leaf boron concentration of the palm are discussed.

Application, Absorption and Translocation of Boron in Oil Palm

SUMMARYFour methods of applying boron to the oil palm were studied and the results indicated that applications to the soil or to leaf axils were best. Tests of five sources of boron showed that alkaline borate fertilizers were superior to boric acid.

Application, Absorption and Translocation of Boron in Oil Palm

SUMMARYThe effects of different frequencies and rates of application of boron fertilizer were studied with regard to uptake of boron by the oil palm. The results indicated that annual or biannual application of this element maintained satisfactory levels in the leaf tissue. Heavy potassium fertilization was found to inhibit boron uptake but nitrogen had no effect.

Optical Study of Silicon Doubly Doped with Boron and Indium Acceptors

The external and internal absorption spectra of silicon doubly doped with boron and indium acceptors is studied. The observed broadening of the boron absorption lines in Si(B, In) is explained by neutral impurity scattering. The presence of indium in the Si(B, In) crystal lattice modifies the valence band Bloch states and hence the configuration interaction between the internal acceptor states and the degenerate P3/2 valence band Bloch states. This modification is found responsible for the observed features of the boron 2p′ internal line in Si(B, In).

The Absorption of Boron by Disks of Plant Storage Tissues

Disks prepared from the storage tissues of carrot (Daucus carota) were able to absorb boron from boric acid solutions (0�1 mM). At 25�C, net influx ceased 3-4 hr after the tissue was placed in boric acid solution. At equilibrium the tissues were able to maintain an internal concentration of diffusible boron in excess of that in the external solution. Boron uptake was inhibited by anoxia, 2,4.dinitrophenol, and at 1�C; and, in the presence of these inhibitors, the equilibrium concentration of boron in the tissues only approached that in the external solution. The capacity of the tissues to accumulate boron developed 2-3 days after the beginning of a washing treatment. Boric acid (0�1 mM) in this washing solution inhibited the development of this capacity.

Characteristics of Boron Absorption by Excised Barley Roots

AbstractBoron absorption by excised barley roots was found to be noncumulative, rapid, and unaffected by pH variations of the substrate in the acid range. However, increases in pH above 7.0 resulted in sharp reductions in absorption. At pH 6.0, changes in substrate temperature, salt composition and level, or addition of KCN and 2,4‐DNP failed to exert any influence on B absorption.These results indicate that B absorption is a physical, non‐metabolic process acting in response to B concentration gradient and that molecular boric acid is favored for absorption.

Local mode absorption from boron arsenic and boron phosphorus pairs in silicon

The local mode absorption in boron doped silicon compensated with either arsenic or phosphorus has been measured. In addition to the absorption from isolated boron, various satellite lines have been detected and ascribed to the vibrations of B-As, B-P and B-B pairs in nearest neighbour sites.

ABSORPTION-LINE BROADENING IN BORON-DOPED SILICON

In boron-doped silicon, the excitation of bound holes from the acceptor ground state to the excited states leads to an infrared absorption-line spectrum. In a recent half-width study of the boron absorption lines, Colbow (1963) separated the various line-broadening contributions for the first time. Part of Colbow's half-widths is now found to be due to external strains introduced by the sample mounting. New half-width measurements of "strain-free" mounted boron-doped silicon are presented, Colbow's work is corrected, and additional information regarding the various broadening contributions is given.

1418. The development and fabrication of a boron absorption tube for spectrographic analysis: J T Dusek, Rep ANL-7164, March 1966 ( Argonne National Lab, Illinois)

1418. The development and fabrication of a boron absorption tube for spectrographic analysis: J T Dusek, Rep ANL-7164, March 1966 ( Argonne National Lab, Illinois)

Boron absorption by crop plants as affected by other nutrients of the medium

Abstract Numerous reports on boron nutrition of plants have been published since WARINGTON (15), using Vicia faba, first discovered in 1923 that boron is essential for the growth of higher plants. Inorganic (7, 9, 11) and organic (1) constituents of the growth medium and climatic conditions such as light intensity (13), photoperiod (5, 16), and drying and wetting of the soil (10) are some of the factors affecting boron uptake by plants.

THE AVAILABLE BORON CONTENT OF THE GENETIC HORIZONS OF SOME ONTARIO SOILS: II. THE RELATIONSHIP BETWEEN BORON ABSORPTION BY SUNFLOWERS AND OTHER SOIL PROPERTIES

The boron absorption by sunflowers in the greenhouse from samples of the genetic horizons of eight Ontario soils increased with increasing water-soluble boron content (R2 = 0.78). The absorption from a group of 17 cultivated surface samples was also positively correlated with water-soluble boron (R2 = 0.54).Clay content had the greatest influence on boron absorption after the influence of water-soluble boron was removed. The two variables in a multiple curvilinear regression accounted for 79% of the variability in absorption from the cultivated surface samples. The absorption increased with increasing clay content up to 15% and then decreased with a further increase in clay up to 20%. Organic matter content had a lesser effect on absorption. The [Formula: see text]-atm moisture value had a relatively large influence on absorption from the profile samples, but essentially no influence on that from the surface samples. The pH and CaCO3 content had very little influence on absorption from either set of samples.

Boron as Paleosalinity Indicator Not Affected by Carbon in Clay Fractions: ABSTRACT

A recently reported inverse correlation between boron and organic carbon in rocks suggests that development of illite-organic complexes during deposition may inhibit boron absorption. The validity of boron as a paleosalinity indicator consequently has been questioned. Analogous studies of illitic clay fractions from the late Visean Lower Yoredale Formation of England revealed no significant correlation between organic carbon and boron. Thus, the validity of boron as a salinity indicator is not affected by organic matter associated with clay fractions. If the reported correlation between boron and organic carbon in rocks is valid, environments which favor organic accumulation could suppress illite authigenesis or inhibit boron absorption. The already-known association betw en boron and salinity suggests that the first interpretation is more probable. Equivalent boron, previously regarded as the best index of paleosalinity, depends on the boron-K2O ratio and K2O concentration in pure illite. However, in previous investigations the K2O concentration in clay fractions was assumed to be the concentration in pure illite. Such a procedure leads to increasing error with increasing organic contamination of clay fractions. Therefore, revised equivalent boron values were calculated for the Lower Yoredale Formation by estimating the organic fraction from carbon analyses and recalculating K2O concentrations in terms of pure illite. These revised values correlate more closely with other geological information and improve discrimination between salinity environments. Organic carbon associated with illite also may be a useful environmental indicator because it correlates closely with facies and distance from shore. It follows that studies of boron, carbon, and potassium in illitic clay fractions could aid environmental discrimination in exploration for offshore stratigraphic traps. End_of_Article - Last_Page 652------------