Search results for "CADMIUM"

Effect of plastic deformation on the anodic electroluminescence accompanying the early stage of electrolytic oxidation of cadmium

1995

In vivo and in vitro effects of nickel and cadmium on the plasmalemma ATPase from rice (Oryza sativa L.) shoots and roots

1992

Abstract Plasmalemma vesicles isolated from rice (Oryza sativa L.) shoots and roots were used to study the effect of different nickel and cadmium concentrations on the Mg2+-ATPase activity. In vivo application of the metals for 5 or 10 days resulted in a stimulation of the enzyme activity in shoots, while either increases or decreases were observed in roots depending on the concentration and the type of ion tested. In contrast, an inhibitory effect was always observed on shoot and root plasmalemma ATPase activity when these ions were applied in vitro. At the organ level, the content of Cd in plants treated with 0.5 mM metal was higher than that of Ni, especially in roots. No correlation bet…

Cadmium and nickel accumulation in rice plants. Effects on mineral nutrition and possible interactions of abscisic and gibberellic acids

1994

Rice plants accumulate high quantities of Cd and Ni when grown for 10 days in a medium containing these heavy metals. Accompanying Cd and Ni uptake, a decrease in shoot and root length was observed, though dry matter accumulation was not affected accordingly. Metal treatments also induced a decrease in K, Ca and Mg contents in the plants, particularly in the shoots, indicating that Cd and Ni interfered not only with nutrient uptake but also with nutrient distribution into the different plant parts. Addition of abscisic acid (ABA) or gibberellic acid (GA3) to the external solution could not overcome the depressing effects of the metals on nutrient acquisition, and even induced a further decr…

Conformationally regulated fluorescent sensors. Study of the selectivity in Zn 2+ versus Cd 2+ sensing

2004

Abstract The Zn 2+ and Cd 2+ complexing properties of four ligands containing a 4,4′-substituted biphenyl moiety are described. Ligands 1 and 3 , containing only one 1-aza-18-crown-6 cavity, lead to selective complexation of Cd 2+ versus Zn 2+ . Ligand 4 , with two crown cavities linked to a tetramethylbenzidine unit, is able to form 1:1 complexes with Zn 2+ and Cd 2+ , showing a higher complexing constant with Zn 2+ than with Cd 2+ , probably due to enthalpic factors. Several complementary experiments suggest that the 1:1 complexes formed by ligand 4 involve both crown cavities acting together to give rise to clamp structures. The formation of this type of zinc complex gives rise to red sh…

Cadmium clusters in CdI2layered crystals: the influence on the optical properties

2007

The influence of overstoichiometric Cd i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI 2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cd i concentration and features in absorption and emission spectra up to concentrations of 10 18 cm -3 . At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of (CdI i ) n clusters are calculated in the frame of Mie theory and are found to correlate with the opti…

Effect of pH, cation concentration and sorbent concentration on cadmium and copper removal by a granular activated carbon

1999

The single adsorption of cadmium and copper from aqueous solutions has been investigated on Darco 12-20 mesh granular activated carbon for a wide range of experimental conditions: pH, metal concentration and carbon concentration. The results showed the efficiency of the activated carbon as sorbent for both metals. Metal removal increases on raising pH and carbon concentration, and decreases on raising the initial metal concentration. The adsorption processes have been modelled using the surface complex formation (SCF) Triple Layer Model (TLM) with a single surface bidentate species or with an overall surface species with fractional stoichiometry. Bidentate stoichiometry considering pH, meta…

Influence of cadmium and nickel on growth, net photosynthesis and carbohydrate distribution in rice plants

1992

Six day old rice seedlings (Oryza sativa L. cv. Bahía) were grown for 5 or 10 days in a nutrient solution with either Cd (0.01, 0.1 mmol/l) or Ni (0.1, 0.5 mmol/l). Both Cd and Ni reduced the length of shoots and roots depending on the concentration and type of ion tested. On the other hand, the dry weight to fresh weight ratio was increased by heavy metal treatments, especially in the aerial part of 0.5 mmol/l Ni treated plants. The application of 0.1 mmol/l Cd and 0.5 mmol/l Ni to the seedlings produced an inhibition of the transport of carbohydrate reserves from the seeds from which plants were developing, to the rest of the plant. Net photosynthesis was also inhibited in treated plants.…

Red and blue luminescent metallo-supramolecular coordination polymers assembled through π–π interactions †

2000

The use of π-stacking interactions to control the aggregation of photo-active metal centres is explored through the design of bis(2,2′;6′,2′′-terpyridyl) metal complexes functionalised with biphenyl ‘tails’. Aryl–aryl interactions control the aggregation of the metal complexes into polymetallic arrays in the solid state. Cobalt(II), ruthenium(II), nickel(II), copper(II), zinc(II) and cadmium(II) bis-ligand complexes and a mixed ligand ruthenium(II) complex have been structurally characterised. The solid-state structures are dependent on which units dominate the π-stacking. For cobalt, ruthenium, nickel and copper, biphenylene–biphenylene interactions lead to linear rod-like arrays, while fo…

Hepatic responses of gene expression in juvenile brown trout (Salmo trutta lacustris) exposed to three model contaminants applied singly and in combi…

2007

Chemical pollution of the aquatic environment is almost always the result of multiple rather than single toxic compounds. The possibility of separating the effects of key risk chemicals from those of others, including their joint effects, is of clear theoretical interest and high technical importance. We addressed this goal using multiple gene expression profiling in the liver of juvenile brown trout (Salmo trutta lacustris) exposed to three model chemicals (cadmium, carbon tetrachloride [CCl4], and pyrene) administered singly, in binary and trinary combinations at low acutely sublethal concentrations, and in the partial dose–response manner. Differentially expressed genes were grouped by c…

Toxico-resistance of Baltic amphipod species to heavy metals

2013

Benthic organisms are important components of aquatic ecosystems and have been widely used to assess environmental pollution. Being very sensitive to a wide range of toxicants amphipods are often used as test objects in eco-toxicological studies. The aim of this study was to compare toxico-resistance of various Baltic amphipod species to exposure of heavy metals. The acute toxicity (48-h LC50 and 96-h LC50) of cadmium (CdCl2), copper (CuSO4) and zinc (ZnSO4 ⋅ 7H2O) was detected experimentally, using juveniles and adults of brackish water amphipods, Monoporeia affinis, Bathyporeia pilosa, Gammarus tigrinus, Pontogammarus robustoides and the freshwater amphipod Gammarus pulex as test objects.…