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Metallic Compounds (metallic + compound)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Evaluating acute toxicity of methyl parathion application in constructed wetland mesocosms,

ENVIRONMENTAL TOXICOLOGY, Issue 5 2004
C. D. Milam
Abstract Wetland ecosystems have reduced ambient levels of various organic and metallic compounds, although their effectiveness on agricultural pesticides is not well documented. Five stations within each of two 10 × 50 m constructed wetlands (two vegetated, two nonvegetated) were selected to measure the fate and effects of methyl parathion (MeP). Following a simulated storm event (0.64 cm of rainfall), aqueous, sediment, and plant samples were collected and analyzed spatially (5, 10, 20, and 40 m from the inlet) and temporally (after 3,10 days) for MeP concentrations and for the impact of those concentrations on the aquatic fauna. Aqueous toxicity to fish decreased spatially and temporally in the vegetated mesocosm. Pimephales promelas survival was significantly reduced, to 68%, at the 10-m station of the nonvegetated wetlands (3 h postapplication), with pesticide concentrations averaging 9.6 ,g MeP/L. Ceriodaphnia in both the vegetated and nonvegetated wetlands was sensitive (i.e., a significant acute response to MeP occurred) to pesticide concentrations through 10 days postapplication. Mean MeP concentrations in water ranged from 0.5 to 15.4 ,g/L and from 0.1 to 27.0 ,g/L in the vegetated and nonvegetated wetlands, respectively. Hyalella azteca aqueous tests resulted in significant mortality in the 5-m vegetated segment 10 days after exposure to MeP (2.2 ,g/L). Solid-phase (10-day) sediment toxicity tests showed no significant reduction in Chironomus tentans survival or growth, except for the sediments sampled 3 h postapplication in the nonvegetated wetland (65% survival). Thereafter, midge survival averaged >87% in sediments sampled from both wetlands. These data suggest that wetlands play a significant role in mitigating the effect of MeP exposure in sensitive aquatic biota. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 471,479, 2004. [source]

Investigation of Mechanical and Microstructural Characteristics of Al,Mg Compounds,

ADVANCED ENGINEERING MATERIALS, Issue 7 2009
Reimund Neugebauer
The presented approach of generating composites offers new possibilities for the combination of two light metal alloys into one semifinished product of high specific strength and corrosion resistance. A test device based on the forming method of lateral extrusion was designed to manufacture metallic compounds. The created interface layer is characterized by the formation of new phases and affects the mechanical properties of the whole compound. [source]

Catalysis of intumescent flame retardancy of polypropylene by metallic compounds,

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2003
Menachem Lewin
Abstract Divalent and multivalent metallic compounds catalyze the flame retardancy performance of intumescent systems based on ammonium polyphosphate (APP) and pentaerythritol (petol) in poly(propylene) (PP). The catalytic effect is shown by increases in the oxygen index (OI) and UL-94 ratings. The effect is exerted by small concentrations of the metallic compounds in the range of 0.1,2.5 wt% of the compositions. The effect increases with the concentration of the catalyst until a maximum is reached. At higher concentrations of the catalyst a decrease in the flame retardancy parameters is observed, accompanied in several cases by a degradation and discoloration of the composition. The catalyst replaces melamine in intumescent systems. Catalytic effectiveness is defined and calculated for a number of compounds. Thermogravimetric parameters, such as initial decomposition temperature, temperature of the transition point and residue-after-transitions (RAT) change in parallel with the catalytic effect of the metal compound concentration. Metal compounds investigated include oxides, acetates, acetyl acetonates, borates and sulfates of Mn, Zn, Mg, Al, Ca, Ba,,V, Co, Ni, Cu, Mo, Zr, and Cr. Mechanistic considerations on the activity of the catalysts are presented. Copyright © 2003 John Wiley & Sons, Ltd. [source]