Mohd Jamil Maah

Heavy metals accumulation in plants growing in ex tin mining catchment

The degree of contamination by heavy metals (arsenic, copper, lead, tin and zinc) in soil and transfer to plants has been studied. Specimens of plant species from five locations in an area of 10 × 10 m were sampled with their corresponding soils. Thirty six plant species including two shallow water aquatic plants were identified. Soil and plant specimens were analyzed by using inductively coupled plasma optical emission spectrometry. It was found that metal concentration in soil was highly variable while concentration of metals in plants directly depends on the concentration of metals it was rooted. Roots showed highest metal concentration followed by leaves, shoots and flowers. Bioconcentraion factor and translocation factor were calculated, representing Cyperus rotundus L. as a potential tin-hyperaccumulator plant, previously not reported in literature. Plant Species Imperata cylindrica, Lycopodium cernuum, Melastoma malabathricum, Mimosa pudica Linn, Nelumbo nucifera, Phragmites australis L., Pteris vittata L. and Salvinia molesta, were metal accumulator while Acacia podalyriaefolia G. Don, Bulb Vanisium, Dillenia reticulate King, Eugenia reinwardtiana, Evodia roxburghiania Hk. f. clarke, Gleichenia linearis, Grewia erythrocarpa Ridl., Manihot esculenta Crantz, Paspalum conjugatum Berguis, Passiflora suberosa, Saccharum officinarum, Stenochlaena palustris (Burm.) Bedd. and Vitis trifolia Linn. were tolerated plant species. All other studied plants were excluders. Identified plant species could be useful for revegetation and erosion control in metals contaminated ex-mining sites. Morphological changes such as reduction in size, change in color and deshaping have also been observed in plant species with high metal values.

First example of cyclodimerisation of a phospha-alkyne to a 1,3-diphosphacyclobutadiene. Syntheses of complexes of the type [M(η5-C5R5){η4-(ButCP)2}] R = H or Me; M = Co, Rh, or Ir): crystal and molecular structure of η5-pentamethylcyclopentadienyl-2,4-di-t-butyl-1,3-diphosphacyclobutadienecobalt(I), [Co(η5-C5Me5){η4-(ButCP)2}]

Displacement of ethylene from [M(η5-C5R5)(C2H4)2], (R = H, M = Co or Rh; R = Me, M = Co, Rh, or Ir) by treatment with ButCP affords complexes containing the novel 2,4-di-t-butyl-1,3-diphosphacyclobutadiene ring.

Chemical Speciation and Potential Mobility of Heavy Metals in the Soil of Former Tin Mining Catchment

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

Factors affecting nucleolytic efficiency of some ternary metal complexes with DNA binding and recognition domains. Crystal and molecular structure of Zn(phen)(edda)

The binding selectivity of the M(phen)(edda) (M=Cu, Co, Ni, Zn; phen=1,10-phenanthroline, edda=ethylenediaminediacetic acid) complexes towards ds(CG)(6), ds(AT)(6) and ds(CGCGAATTCGCG) B-form oligonucleotide duplexes were studied by CD spectroscopy and molecular modeling. The binding mode is intercalation and there is selectivity towards AT-sequence and stacking preference for A/A parallel or diagonal adjacent base steps in their intercalation. The nucleolytic properties of these complexes were investigated and the factors affecting the extent of cleavage were determined to be: concentration of complex, the nature of metal(II) ion, type of buffer, pH of buffer, incubation time, incubation temperature, and the presence of hydrogen peroxide or ascorbic acid as exogenous reagents. The fluorescence property of these complexes and its origin were also investigated. The crystal structure of the Zn(phen)(edda) complex is reported in which the zinc atom displays a distorted trans-N(4)O(2) octahedral geometry; the crystal packing features double layers of complex molecules held together by extensive hydrogen bonding that inter-digitate with adjacent double layers via pi...pi interactions between 1,10-phenanthroline residues. The structure is compared with that of the recently described copper(II) analogue and, with the latter, included in molecular modeling.

Synthesis, characterization and biological properties of cobalt(II) complexes of 1,10-phenanthroline and maltol

The synthesis and characterization of two cobalt(II) complexes, Co(phen)(ma)Cl 1 and Co(ma)(2)(phen) 2, (phen=1,10-phenanthroline, ma(-)=maltolate or 2-methyl-4-oxo-4H-pyran-3-olate) are reported herein. The complexes have been characterized by FTIR, CHN analysis, fluorescence spectroscopy, UV-visible spectroscopy, conductivity measurement and X-ray crystallography. The number of chelated maltolate ligands seems to influence their DNA recognition, topoisomerase I inhibition and antiproliferative properties.

Enhancing the radiation dose detection sensitivity of optical fibres

A method for improving the thermoluminescence (TL) yield of silica-based optical fibres is demonstrated. Using silica obtained from a single manufacturer, three forms of pure (undoped) fibre (capillary-, flat-, and photonic crystal fibre (PCF)) and two forms of Ge-doped fibre (capillary- and flat-fibre) were fabricated. The pure fibre samples were exposed to 6 and 21MeV electrons, the doped fibres to 6MV photons. The consistent observation of large TL yield enhancement is strongly suggestive of surface-strain defects generation. For 6MeV irradiations of flat-fibre and PCF, respective TL yields per unit mass of about 12.0 and 17.5 times that of the undoped capillary-fibre have been observed. Similarly, by making a Ge-doped capillary-fibre into flat-fibre, the TL response is found to increase by some 6.0 times. Thus, in addition to TL from the presence of a dopant, the increase in fused surface areas of flat-fibres and PCF is seen to be a further important source of TL. The glow-curves of the undoped fibres have been analysed by computational deconvolution. Trap centre energies have been estimated and compared for the various fibre samples. Two trap centre types observed in capillary-fibre are also observed in flat-fibre and PCF. An additional trap centre in flat-fibre and one further trap centre in PCF are observed when compared to capillary fibre. These elevated-energy trap centres are linked with strain-generated defects in the collapsed regions of the flat fibre and PCF.

Synthesis and structural characterization of an unusual η3-ligated 1,3-diphosphacyclobutadiene molybdenum complex via cyclodimerization of a phosphaalkyne. Crystal structure of [Mo(η5-C9 H7)(CO)2P-η3-(tBu)CPC(tBu)PFBF3]

Abstract The phosphaalkyne t BuCP undergoes cyclodimerization at a molybdenum centre to afford a 1,3-diphosphacyclobutadiene complex in which, unusually, the four-membered ring is η 3 ligated to the metal.

Nickel(II) Complex of Polyhydroxybenzaldehyde N4-Thiosemicarbazone Exhibits Anti-Inflammatory Activity by Inhibiting NF-κB Transactivation

Background The biological properties of thiosemicarbazone have been widely reported. The incorporation of some transition metals such as Fe, Ni and Cu to thiosemicarbazone complexes is known to enhance its biological effects. In this study, we incorporated nickel(II) ions into thiosemicarbazone with N4-substitution groups H3L (H; H3L1, CH3; H3L2, C6H5; H3L3 and C2H5; H3L4) and examined its potential anti-inflammatory activity. Methodology/Principal Findings Four ligands (1–4) and their respective nickel-containing complexes (5–8) were synthesized and characterized. The compounds synthesized were tested for their effects on NF-κB nuclear translocation, pro-inflammatory cytokines secretion and NF-κB transactivation activity. The active compound was further evaluated on its ability to suppress carrageenan-induced acute inflammation in vivo. A potential binding target of the active compound was also predicted by molecular docking analysis. Conclusions/Significance Among all synthesized compounds tested, we found that complex [Ni(H2L1)(PPh3)]Cl (5) (complex 5), potently inhibited IκBα degradation and NF-κB p65 nuclear translocation in LPS-stimulated RAW264.7 cells as well as TNFα-stimulated HeLa S3 cells. In addition, complex 5 significantly down-regulated LPS- or TNFα-induced transcription of NF-κB target genes, including genes that encode the pro-inflammatory cytokines TNFα, IFNβ and IL6. Luciferase reporter assays confirmed that complex 5 inhibited the transactivation activity of NF-κB. Furthermore, the anti-inflammatory effect of complex 5 was also supported by its suppressive effect on carrageenan-induced paw edema formation in wild type C57BL/6 mice. Interestingly, molecular docking study showed that complex 5 potentially interact with the active site of IKKβ. Taken together, we suggest complex 5 as a novel NF-κB inhibitor with potent anti-inflammatory effects.

Study of mango biomass (Mangifera indica L) as a cationic biosorbent

Unfertilizable fruiting buds of mango plant Mangifera Indica L, an agrowaste, is used as a biomass in this study. The efficacy of the biosorbent was tested for the removal of lead, copper, zinc and nickel metal ions using batch experiments in single and binary metal solution under controlled experimental conditions. It is found that metal sorption increases when the equilibrium metal concentration rises. At highest experimental solution concentration used (150 mg/L), the removal of metal ions were 82.76 % for lead, 76.60 % for copper, 63.35 % for zinc and 59.35 % for nickel while at lowest experimental solution concentration (25 mg/L), the removal of metal ions were 92.00% for lead, 86.84 % for copper, 83.96 % for zinc and 82.29 % for nickel. Biosorption equilibrium isotherms were plotted for metal uptake capacity (q) against residual metal concentrations (Cf) in solution. The q versus Cf sorption isotherm relationship was mathematically expressed by Langmuir and Freundlich models. The values of separation factor were between zero and one indicating favourable sorption for four tested metals on the biosorbent. The surface coverage values were approaching unity with increasing solution concentration indicating effectiveness of biosorbent under investigation. The non-living biomass of Mangifera indica L present comparable biosorption capacity for lead, copper, zinc and nickel metal ions with other types of biosorbent materials found in literature and is effective to remove metal ions from single metal solutions as well as in the presence of other co-ions with the main metal of solution.

Trace metal geochemical associations in sediments from the culture-bed of Anadara granosa

Abstract Geochemical associations of certain trace metals in sediments from the culture-bed of Anadara granosa were studied. Trace metals were sequentially extracted from texturally homogeneous sediments collected along the mudflat of Kuala Juru, Malaysia. Mean total concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn were 2.5, 41, 11 485, 197, 19, 44, and 266 μg g −1 , respectively. Mean concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn in the non-residual fraction on the other hand, were 1.0, 17, 4566, 138, 14, 13, and 210 μg g −1 , respectively. These concentrations accounted for 40, 42, 40, 70, 76, 30, and 29% of total metal concentrations present in sediments, respectively. In the nonresidual fraction, 6.8% Cd, 4.9% Cu, 0.04% Fe, 13% Mn, 8% Ni, 12% Pb, and 9.8% Zn and 4.9% Cd, 1.1% Cu, 1.1% Fe, 13% Mn, 3.7% Ni, 7.5% Pb, and 10% Zn were present in the exchangeable and easily reducible fractions, respectively. In the moderately reducible fraction, 40% Cd, 6.9% Cu, 49% Fe, 11% Mn, 1.1% Ni, and 21% Zn were demonstrated to be associated with this fraction. Lead was, however, not detected in this fraction. Most trace metals were shown to be associated with the organic/sulphide fraction having 48, 87, 50, 64, 87, 80, and 59% of Cd, Cu, Fe, Mn, Ni, Pb, and Zn, respectively. It appears that the exchangeable, easily reducible and moderately reducible fractions in most cases are considered to be geochemically insignificant in the sorption of trace metals in partially anaerobic sediments investigated. The organic/sulphide fraction was, however, assumed to have an important role as a reservoir for trace metals in the sediments. As these metals were poorly concentrated in the exchangeable phase, the present results tend to indicate that the economically important bivalve, A. granosa is not at risk of being heavily contaminated by toxicologically significant trace metals.