Accumulation of arsenic in tissues of rice plant (Oryza sativa L.) and its distribution in fractions of rice grain

A study was conducted to investigate the accumulation and distribution of arsenic in different fractions of rice grain (Oryza sativa L.) collected from arsenic affected area of Bangladesh. The agricultural soil of study area has become highly contaminated with arsenic due to the excessive use of arsenic-rich underground water (0.070 ± 0.006 mg l-1, n = 6) for irrigation. Arsenic content in tissues of rice plant and in fractions of rice grain of two widely cultivated rice varieties, namely BRRI dhan28 and BRRI hybrid dhan1, were determined. Regardless of rice varieties, arsenic content was about 28- and 75-folds higher in root than that of shoot and raw rice grain, respectively. In fractions of parboiled and non-parboiled rice grain of both varieties, the order of arsenic concentrations was; rice hull > bran-polish > brown rice > raw rice > polish rice. Arsenic content was higher in non-parboiled rice grain than that of parboiled rice. Arsenic concentrations in parboiled and non-parboiled brown rice of BRRI dhan28 were 0.8 ± 0.1 and 0.5 ± 0.0 mg kg-1 dry weight, respectively while those of BRRI hybrid dhan1 were 0.8 ± 0.2 and 0.6 ± 0.2 mg kg-1 dry weight, respectively. However, parboiled and non-parboiled polish rice grain of BRRI dhan28 contained 0.4 ± 0.0 and 0.3 ± 0.1 mg kg-1 dry weight of arsenic, respectively while those of BRRI hybrid dhan1 contained 0.43 ± 0.01 and 0.5 ± 0.0 mg kg-1 dry weight, respectively. Both polish and brown rice are readily cooked for human consumption. The concentration of arsenic found in the present study is much lower than the permissible limit in rice (1.0 mg kg-1) according to WHO recommendation. Thus, rice grown in soils of Bangladesh contaminated with arsenic of 14.5 ± 0.1 mg kg-1 could be considered safe for human consumption. © 2007 Elsevier Ltd. All rights reserved

Influence of EDTA and chemical species on arsenic accumulation in Spirodela polyrhiza L. (duckweed)

金沢大学大学院理工研究域物質化学系The influence of ethylenediaminetetraacetic acid (EDTA) and chemical species on arsenic accumulation in aquatic floating macrophyte Spirodela polyrhiza L. (duckweed) was investigated. The uptake of inorganic arsenic species (arsenate; As(V) and arsenite; As(III)) into the plant tissue and their adsorption on iron plaque of plant surfaces were significantly (p0.05) by EDTA addition to the culture media while its concentration in CBE-extract decreased significantly (p<0.05). The As(inorganic)/Fe ratios in plant were higher than those of CBE-extract which indicate the increased uptake of these arsenic species into the plant relative to the iron. The lower As(organic)/Fe ratios in plant and on CBE-extract suggest the reduction of accumulation of these arsenic species relative to the iron. © 2007 Elsevier Inc. All rights reserved

Non-destructive separation of metal ions from wastewater containing excess aminopolycarboxylate chelant in solution with an ion-selective immobilized macrocyclic material

金沢大学理工研究域物質化学系Although the excellent metal-binding capacities of aminopolycarboxylate chelants (APCs) facilitate their extensive use, pre- and post-toxicity of APCs and their high persistence in aquatic environments evoke concerns. Several treatment techniques with a principal focus on the degradation of APCs at the pre-release step have been proposed. Here, we report a technique for the separation of metal ions from waste solution containing excess APCs using a solid phase extraction system with an ion-selective immobilized macrocyclic material, commonly known as a molecular recognition technology (MRT) gel. Synthetic metal solutions with 100-fold chelant content housed in H2O matrices were used as samples. The MRT gel showed a higher recovery rate compared with other SPE materials at 20 °C using a flow rate of 0.2 mL min-1. The effects of solution pH, metal-chelant stability constants and ionic radii were assessed for 32 metals. Compared to the conventional treatment options for such waste solutions, our proposed technique has the advantage of non-destructive separation of both metal ions and chelants. © 2010 Elsevier Ltd. All rights reserved

Decoherence of electron spin qubits in Si-based quantum computers

Direct phonon spin-lattice relaxation of an electron qubit bound by a donor impurity or quantum dot in SiGe heterostructures is investigated. The aim is to evaluate the importance of decoherence from this mechanism in several important solid-state quantum computer designs operating at low temperatures. We calculate the relaxation rate $1/T_1$ as a function of [100] uniaxial strain, temperature, magnetic field, and silicon/germanium content for Si:P bound electrons. The quantum dot potential is much smoother, leading to smaller splittings of the valley degeneracies. We have estimated these splittings in order to obtain upper bounds for the relaxation rate. In general, we find that the relaxation rate is strongly decreased by uniaxial compressive strain in a SiGe-Si-SiGe quantum well, making this strain an important positive design feature. Ge in high concentrations (particularly over 85%) increases the rate, making Si-rich materials preferable. We conclude that SiGe bound electron qubits must meet certain conditions to minimize decoherence but that spin-phonon relaxation does not rule out the solid-state implementation of error-tolerant quantum computing.Comment: 8 figures. To appear in PRB-July 2002. Revisions include: some references added/corrected, several typos fixed, a few things clarified. Nothing dramati

Complexation behavior of SrII and geochemically-related elements (MgII, CaII, BaII, and YIII) with biodegradable aminopolycarboxylate chelators (GLDA and HIDS)

金沢大学理工研究域物質化学系The complexation of SrII and geochemically-related elements (MgII, CaII, BaII, and YIII) with biodegradable aminopolycarboxylate chelators (DL-2-(2-carboxymethyl)nitrilotriacetic acid (GLDA) and 3-hydroxy-2,2′-iminodisuccinic acid (HIDS)) was evaluated with the objective of using in the chemical-induced washing remediation of radioactive solid waste. The stability constants (log10KML) for metal-chelator (ML) complexes between M (MgII, CaII, SrII, BaII, or YIII) and L (GLDA or HIDS) in the aqueous matrix was derived from experimental potentiometric data (M:L = 1:1; ionic strength, I = 0.10 mol·dm− 3; T = 25 ± 0.1 °C). The formation of ML2 − species was dominant in the systems with MgII, CaII, SrII, or BaII, while M(OH)L2 − or M(OH)2L3 − was the major species with YIII. The stability of YIII-L complexes was higher than that of MgII, CaII, SrII, or BaII, while the order for complexation strength of GLDA and HIDS was not similar with divalent ions: M-GLDA (log10KMg-L  log10KSr-L > log10KBa-L), M-HIDS (log10KMg-L > log10KCa-L > log10KSr-L > log10KBa-L). The conditional stability constants for the ML systems was also derived in terms of pH (2 to 12), and compared with that of EDTA and EDDS. The data trend indicated that the overall stability of the complexes of MgII, CaII, SrII, BaII, or YIII with GLDA or HIDS was better than the biodegradable chelator EDDS, which was frequently recommended as the alternative to EDTA. © 2017 Elsevier B.V.Embargo Period 12 month

Volumetric and viscometric behavior of the binary system: (Hexan-1-ol + p -Xylene)

金沢大学理工研究域物質化学系Densities and viscosities for the binary mixtures of hexan-1-ol with p-xylene have been measured at a number of mole fractions at T = (303.15, 313.15, and 323.15) K. The excess molar volumes and viscosity deviations have been calculated from the experimental results and have been fitted to the Redlich-Kister polynomial equation. © 2010 American Chemical Society

Physicochemical properties of moringa oleifera Lam. seed oil of the indigenous-cultivar of Bangladesh

金沢大学理工研究域物質化学系Moringa oleifera Lam. seed oil of the indigenous-cultivar of Bangladesh was extracted using n-hexane (H), light petroleum ether (LPE) (bp 40-60C) and chloroform/methanol (50:50, v/v) mixture (CM). The oil content ranged from 37.50 (H) to 40.20% (CM). The moisture, protein, ash and crude fiber contents of seed residues, and the density, refractive index, color, acidity, saponification value, iodine value, unsaponifiable matter content, oxidative state, sterols, tocopherols and fatty acid composition of the extracted oil were determined. The oil contained a high amount of oleic acid (C18:1) of up to 74.41% and a high ratio of monounsaturated to saturated fatty acids with moderate oxidative stability. The results of the present study were compared with those reported in literature for different regional habitats and species variants. © 2009, Wiley Periodicals, Inc

Selective recovery of indium from lead-smelting dust

Non-ferrous smelting dust, especially lead-smelting dust (LSD), contains percent levels of indium and thus constitutes a novel indium resource. The main difficulty in recovering indium from LSD is the coexisting presence of lead and zinc. In this study, a unique indium separation process was designed, combining techniques that involve washing with a chelant, leaching with acid and precipitation as hydroxide. The majority of the Pb in the LSD was selectively separated during chelant-assisted washing with ethylenediaminedisuccinate (EDDS), while the residual Pb was diminished through an acid leaching treatment with a mixed solution of sulfuric acid and hydrochloric acid. The chelant washing step also ensures a decrease in the raw LSD weight at a ratio of approximately 82% due to the removal of lead and counterions such as sulfate, and the washing step also minimizes the consumption of corrosive acids in the subsequent step. Selective indium separation from LSD is further complicated by the similarity of the behavior of zinc during the acid leaching step. Therefore, hydroxide precipitation at pH 5 has been introduced as the final step, ensuring the maintenance of zinc as a soluble species in the supernatant and the selective separation of indium (~88%) as a hydroxide precipitate. © 2015 Elsevier B.V.Embargo Period 48mouth