Aquatic plants are known to accumulate heavy metals. In this study, Duckweed plants (Lemna polyrrhiza L.) were exposed to different concentrations of Cd and Pb. Various physio-biochemical parameters (fresh weight, chlorophyll content, soluble protein, soluble sugars, proline content and metal absorption) were studied. At lower metal concentrations, an increase in proline, protein and sugar was ...

 In a complementary field study, the concentrations of some metals (Cu, Ag, Pb, Zn, Ni, Co, Mn, Fe, As, Cd, Cr, Mg and Ba) were measured in clam Solen dactylus, sediments and water collected at two stations (Park-e-Qadir, 56° 20/ E, 27° 11/ and Nakhl-e-Nakhoda, 56° 23/ E, 27° 10/ N) of Bandar Abbas coastal waters of the Persian Gulf in November 2008 and February 2009 showing different contamina...

Introduction: Bulk ureilites have near-chondritic abundances of trace siderophile elements (Fig. 1), which is difficult to reconcile with any igneous model for their silicates [1]. It is particularly problematic [2-4] for the smelting model in which silicate mg (molar Mg/[Mg+Fe]) is controlled by pressure-dependent carbon redox reactions [5-7]. The smelting reaction (FeO+C→Fe+CO) predicts a cor...

 In a complementary field study, the concentrations of some metals (Cu, Ag, Pb, Zn, Ni, Co, Mn, Fe, As, Cd, Cr, Mg and Ba) were measured in clam Solen dactylus, sediments and water collected at two stations (Park-e-Qadir, 56° 20/ E, 27° 11/ and Nakhl-e-Nakhoda, 56° 23/ E, 27° 10/ N) of Bandar Abbas coastal waters of the Persian Gulf in November 2008 and February 2009 showing different contamina...

The role of metal cations (Mg(2+)) in the cleavage reaction of fully hydrated RNA enzymes is investigated via Car-Parrinello calculations. We find that the action of two metal catalysts is the most efficient way to promote, on one hand, the proton abstraction from O(2)(')-H that triggers the nucleophilic attack and, on the other hand, the weakening and subsequent cleavage of the P-O(5)(') bond....

The effects of various metal ions (Na, K, Ca, Mg, Al, Co) and anions (Cl, and CH3COO) on two cellulases were investigated. Fitting of the data to Michaelis-Menten kinetics showed that Al noncompetitively inhibited cellulase (Km = 22.68 g/L; Vmax = 0.269 mg/min at 5.0 mmol/L AlCl3) and Mg competitively inhibited cellulase (Km = 50.0 g/L; Vmax = 0.434 mg/min at 10.0 mmol/L MgCl2) Different metal ...

Stream sediments from the mining and smelting district of Príbram, Czech Republic, were studied to determine the degree, sources and dispersal of metal contamination using a combination of bulk metal and mineralogical determinations, sequential extractions and Pb isotopic analyses. The highest metal concentrations were found 3-4 km downstream from the main polymetallic mining site (9800 mg Pb k...

Calculations of the statistical equilibrium of magnesium in the solar photosphere have shown that NLTE populations hardly affect Mg line formation in the Sun. However, in metal-poor dwarfs and giants the influence of electron collisions is reduced, and the ultraviolet radiation field, enhanced due to reduced background line opacity, results in more pronounced NLTE effects. In the photosphere of...

We explore the local electronic signatures of molecular adsorption at coordinatively unsaturated binding sites in the metal-organic framework Mg-MOF-74 using X-ray spectroscopy and first-principles calculations. In situ measurements at the Mg K-edge reveal distinct pre-edge absorption features associated with the unique, open coordination of the Mg sites which are suppressed upon adsorption of ...

Glycogen synthase kinase 3β (GSK3β) is a serine/threonine kinase that requires two cofactor Mg(2+) ions for catalysis in regulating many important cellular signals. Experimentally, Li(+) is a competitive inhibitor of GSK3β relative to Mg(2+), while this mechanism is not experienced with other group I metal ions. Herein, we use native Mg(2)(2+)-Mg(1)(2+) GSK3β and its Mg(2)(2+)-M(1)(+) (M = Li, ...