Effect of pH on boron adsorption in some soils of Parana, Brazil

Temporary B deficiency can be triggered by liming of acid soils because of increased B adsorption at higher soil pH. Plants respond directly to the activity of B in soil solution and only indirectly to B adsorbed on soil constituents. Because the range between deficient and toxic B concentration is relatively narrow, this poses difficulty in maintaining appropriate B levels in soil solution. Thus, knowledge of the chemical behavior of B in the soil is particularly important. The present study investigated the effect of soil pH on B adsorption in four soils of Parana State, and to correlate these values with the physical and chemical properties of the soils. Surface samples were taken from a Rhodic Hapludox, Arenic Hapludalf, Arenic Hapludult, and one Typic Usthorthent. To evaluate the effect of pH on B adsorption, subsamples soil received the application of increasing rates of calcium carbonate. Boron adsorption was accomplished by shaking 2.0 g soil, for 24 h, with 20 mL of 0.01 mol L-1 NaCl solution containing different concentrations (0.0, 0.1, 0.2, 0.4, 0.8, 1.2, 1.6, 2.0, and 4.0 mg B L-1). Sorption was fitted to non-linear form of the Langmuir adsorption isotherm. Boron adsorption increased as concentration increased. Boron adsorption was dependent on soil pH, increasing as a function of pH in the range between 4.6 and 7.4, although the bonding energy has decreased. Maximum adsorption capacity (MAC) of B was observed in the Arenic Hapludalf (49.8 mg B kg(-1) soil) followed by Arenic Hapludult (22.5 mg kg(-1)), Rhodic Hapludox (17.4 mg kg(-1)), and Typic Usthorthent (7.0 mg kg(-1)). The organic matter content, clay content, and aluminum oxide content (Al2O3) were the soils properties that affecting the B adsorption on Parana soils.

Dynamical aspects of the unzipping of multiwalled boron nitride nanotubes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrodeposition of Ni-B and Ni-Co-B Alloys by Using Boric Acid as Boron Source

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Interaction of Organophosphorus Pesticides with DNA Nucleotides on a Boron-Doped Diamond Electrode

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Applying boron to coconut palm plants: effects on the soil, on the plant nutritional status and on productivity boron to coconut palm trees

Boron, one of the micronutrients frequently found in low levels in tropical soils affects nutrition and productivity of coconut palm trees essentially cultivated in tropical climates. The objective of this research study was to evaluate the effect of boron on the nutritional status of the plant and its productivity when artificially applied to the culture soil. The experiment was carried out in a four year old, artificially irrigated, dwarf coconut palm orchard in Brazil, between January, 2005 and October, 2006. The soil was a red yellow Latosol (B: 0.18 mg dm(-3)). The treatments consisted in the application of five boron dosages: zero, 1, 2, 4, and 6 kg ha(-1). In the field, the treatments were arranged according to a completely randomized block design, with four replications. Boron (borax) dosages were applied in equal halves directly into the soil in the months of January and February of 2005. Boron concentration in the soil and plant and plant productivity were evaluated. The higher palm tree production was associated to levels of 0.6mg dm(-3) of B in the soil and 23.5mg kg(-1) in leaves. Ninety five percent of palm trees maximum production was obtained with the use of a boron dosage of 2,1kg ha(-1).

Carbohydrate production and transport in cotton cultivars grown under boron deficiency

An adequate supply of boron (B) is required for the optimal growth and development of cotton (Gossypium hirsutum L.) plants, but the low phloem mobility of B limits the possibilities of correcting B deficiency. There are indications that different cotton cultivars could have different responses to B deficiency. The differences in responses of cotton cultivars to B regarding photoassimilate production and transport were studied in a greenhouse experiment with nutrient solution. Treatments consisted of three cotton cultivars (FMT 701, DP 604BG and FMX 993) and five concentrations of B (0.0, 2.5, 5.0, 10.0 and 20.0 mu mol L-1). Sampling began at the phenological stage B1 (first square) and continued for four weeks. The leaf area and the number of reproductive branches and structures decreased due to B deficiency. A higher level of abortion of reproductive structures was observed under B deficiency. Boron deficiency increased the internal CO2 concentration but decreased the transpiration rate, stomatal conductance and photosynthesis. Despite the decrease in photosynthesis, nonstructural carbohydrates accumulated in the leaves due to decreased export to bolls in B-deficient plants. The response to B deficiency is similar among cotton cultivars, which shows that the variability for this trait is low even for cultivars with different genetic backgrounds.

Boron uptake and translocation in some cotton cultivars

Boron (B) is the most deficient micronutrient in cotton (Gossypium hirsutum L.). It is generally accepted that B is immobile in cotton phloem, but some cultivars could remobilize the nutrient. In order to further understand B uptake and mobility in various cotton cultivars two experiments were conducted.In experiment-1, cotton cultivars were grown in B-10 enriched or natural abundance nutrient solutions for 4 weeks and transferred to nutrient solutions ranging from deficient to sufficient in B. In experiment-2 B-10 enriched boric acid was applied to cotton leaves and B mobilization was determined.In deficient plants, B previously supplied to roots was remobilized from older to younger plant tissues, but the amount was insufficient to maintain growth. Boron deficiency symptoms appeared and progressed with time. Boron applied to leaves was taken up and remobilized within 24 h. Boron mobilization was higher to plant parts above the treated region.Boron uptake and mobilization was similar among cotton cultivars. Boron applied to cotton leaves shows a preferential translocation to younger tissues. Foliar sprays of B to cotton may be used to cope with a temporary deficiency, but to achieve full growth and development B must be available to cotton throughout the plant cycle.

Transport properties of polycrystalline boron doped diamond

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preliminary in vitro and ex vivo evaluation of afzelin, kaempferitrin and pterogynoside action over free radicals and reactive oxygen species

Biological activities of flavonoids have been extensively reviewed in literature. The biochemical profile of afzelin, kaempferitrin, and pterogynoside acting on reactive oxygen species was investigated in this paper. The flavonoids were able to act as scavengers of the superoxide anion, hypochlorous acid and taurine chloramine. Although flavonoids are naturally occurring substances in plants which antioxidant activities have been widely advertised as beneficial, afzelin, kaempferitrin, and pterogynoside were able to promote cytotoxic effect. In red blood cells this toxicity was enhanced, depending on flavonoids concentration, in the presence of hypochlorous acid, but reduced in the presence of 2,20 -azo-bis(2-amidinopropane) free radical. These flavonoids had also promoted the death of neutrophils, which was exacerbated when the oxidative burst was initiated by phorbol miristate acetate. Therefore, despite their well-known scavenging action toward free radicals and oxidants, these compounds could be very harmful to living organisms through their action over erythrocytes and neutrophils.

Enhanced photoelectrocatalytic degradation of an acid dye with boron-doped TiO2 nanotube anodes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Detection of several carbohydrates using boron-doped diamond electrodes modified with nickel hydroxide nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The oxidation of p-phenylenediamine, an ingredient used for permanent hair dyeing purposes, leads to the formation of hydroxyl radicals: oxidative stress and DNA damage in human immortalized keratinocytes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural and Magnetic Properties of Neodymium - Iron - Boron Clusters

Using inert gas condensation techniques the properties of sputtered neodymium-iron-born clusters were investigated. A D.C. magnetron sputtering source created vaporous Nd-Fe-B which was then condensed into clusters and deposited onto silicon substrates. A composite target of Nd-Fe-B discs on an iron plate and a composite target of Nd-(Fe-Co)-B were utilized to create clusters. The clusters were coated with a carbon layer through R.F. sputtering to prevent oxidation. Samples were investigated in the TEM and showed a size distribution with an average particle diameter of 8.11 nm. The clusters, upon deposition, were amorphous as indicated by diffuse diffraction patterns obtained through SAD. The EDS showed compositionally a direct correlation in the ratio of rare-earth to transition metals between the target and deposited samples. The magnetic properties of the as-deposited clusters showed superparamagnetic properties at high temperatures and ferromagnetic properties at low temperatures; these properties are indicative of rare-earth transition metal amorphous clusters. Annealing of samples showed an initial increase in the coercivity. Samples were annealed in an inert gas atmosphere at 600o C for increasing amounts of time. The samples showed an initial increase in coercivity, but showed no additional increases with additional annealing time. SAD of annealed cluster samples showed the presence of Nd2Fe17 and a bcc-Nd phase. The bcc-Nd is the result of oxidation at high temperatures created during annealing and surface interface energy. The magnetic properties of the annealed samples showed weak coercivity and a saturation magnetization equivalent to that of Nd2Fe17. The annealed clusters showed a slight increase in coercivity at low temperatures. These results indicate a loss of boron during the sputtering process.

Optical properties of boron carbide (B5C) thin films fabricated by plasma-enhanced chemical-vapor deposition

Variable angle of incidence spectroscopic ellipsometry was used to determine the optical constants near the band edge of boron carbide (B5C) thin films deposited on glass and n-type Si(111) via plasma-enhanced chemical-vapor deposition. The index of refraction n, the extinction coefficient k, and the absorption coefficient are reported in the photon energy spectrum between 1.24 and 4 eV. Ellipsometry analysis of B5C films on silicon indicates a graded material, while the optical constants of B5C on glass are homogeneous. Line shape analyses of absorption data for the films on glass indicate an indirect transition at approximately 0.75 eV and a direct transition at about 1.5 eV. ©1996 American Institute of Physics.