Spatial patterns of cadmium and lead deposition on and adjacent to National Park Service lands in the vicinity of Red Dog Mine, Alaska

Heavy metal escapement associated with ore trucks is known to occur along the DeLong Mountain Regional Transportation System (DMTS) haul road corridor in Cape Krusenstern National Monument, northwest Alaska. Heavy metal concentrations in Hylocomium splendens moss (n = 226) were used in geostatistical models to predict the extent and pattern of atmospheric deposition of Cd and Pb on Monument lands. A stratified grid-based sample design was used with more intensive sampling near mine-related activity areas. Spatial predictions were used to produce maps of concentration patterns, and to estimate the total area in 10 moss concentration categories. Heavy metal levels in moss were highest immediately adjacent to the DMTS haul road (Cd > 24 mg/kg dw; Pb > 900 mg/kg dw). Spatial regression analyses indicated that heavy metal deposition decreased with the log of distance from the DMTS haul road and the DMTS port site. Analysis of subsurface soil suggested that observed patterns of heavy metal deposition reflected in moss were not attributable to subsurface lithology at the sample points. Further, moss Pb concentrations throughout the northern half of the study area were high relative to concentrations previously reported from other Arctic Alaska sites. Collectively, these findings indicate the presence of mine-related heavy metal deposition throughout the northern portion of Cape Krusenstern National Monument. Geospatial analyses suggest that the Pb depositional area extends 25 km north of the haul road to the Kisimilot/Iyikrok hills, and possibly beyond. More study is needed to determine whether higher moss heavy metal concentrations in the northernmost portion of the study area reflect deposition from mining-related activities, weathering from mineralized Pb/Zn outcrops in the broader region, or a combination of the two. South of the DMTS haul road, airborne deposition appears to be constrained by the Tahinichok Mountains. Heavy metal levels continue to diminish south of the mountains, reaching a minimum in the southernmost portion of the study area near the Igichuk Hills (45 km from the haul road). The influence of the mine site was not studied.     

Development of a Catalyst Based on Titanium Nanoparticles in a Zeolite Matrix

Glass and Ceramics - A catalyst was developed in the form of a composite based on a zeolite matrix modified with titanium nanoparticles based on zeolite raw materials from the Kulikovskoe deposit...     

Application of Granulometry for Rapid Assessment of the Performance Properties of Acid-Activated Sedimentary Rocks

Glass and Ceramics - The granulometric compositions of native and acid-activated rocks containing aluminosilicates are compared. It is shown that in water rocks gradually dissolve and the particle...     

Producing Polydicyclopentadiene from Lower-Grade Dicyclopentadiene

Russian Engineering Research - Polymer samples based on polydicyclopentadiene produced from Russian dicyclopentadiene are investigated by thermogravimetric analysis and differential scanning...     

Fabrication and characterization of poly(methyl methacrylate)/CaCu3Ti4O12 composites

Composites comprising Poly(Methyl Methacrylate) (PMMA) and CaCu₃Ti₄O₁₂ (CCTO) via melt mixing followed by hot pressing were fabricated. These were characterized using X‐ray diffraction, thermo gravimetric, scanning electron microscopy, and Impedance analyzer for their structural, morphology, and dielectric properties. Composites were found to have better thermal stability than that of pure PMMA. The composite, with 38 Vol % of CCTO (in PMMA), exhibited remarkably low dielectric loss at high frequencies and the low frequency relaxation is attributed to the space charge polarization/MWS effect. Theoretical models were employed to rationalize the dielectric behavior of these composites. At higher temperatures, the relaxation peak shifts to higher frequencies, due to the merging of both β and α relaxations into a single dielectric dispersion peak. The AC conductivity in the high frequency region was attributed to the electronic polarization. POLYM. ENG. SCI., 54:551–558, 2014. © 2013 Society of Plastics Engineers     

Environmental ageing studies of impact modified waste polypropylene

Toughness of rigid thermoplastic is an important mechanical property in polymer technology. In the present study, toughening of waste polypropylene (WPP) with ethylene–propylene–diene monomer (EPDM) rubber at different loading levels was carried out by melt blending at 180 °C. The EPDM-toughened WPP samples were characterized for its thermo-mechanical properties. The effect of carbon black (5 wt%) as a functional filler in WPP/EPDM to impart UV protection was also studied. The test sheets were subjected to natural weathering in variable climatic conditions for a 4-month period of time and were taken out at regular intervals for characterization. The waste PP underwent excessive degradation as the mechanical strength properties such as tensile, flexural and impact strengths were reduced drastically. On the other hand, WPP containing varying proportions of EPDM and carbon black showed better retention of strength properties. The percentage degree of crystallinity has been unusually increased after the environmental degradation due to chemi-crystallization. The impact-modified WPP which contains carbon black retained the processability even after the environmental aging. After aging, the non-stabilized systems were shown extensive change, whereas the structural integrity has been well retained of the toughened WPP containing carbon black as was evident from SEM and optical photomicroscopy.     

Investigation of the Device Electrical Parameters for Homo and Hetero Junction Based TFETs

Silicon - This paper presents the analytical approximation of device physics of heterojunction based double gate (DG) Tunnel field effect transistors (TFETs) in terms of potential distribution,...     

Experimental Investigations on Microstructure,Mechanical Behavior and Tribological analysis of AA5154/SiC Composites by Stir Casting

Silicon - Aluminum metal matrix composites (MMCs) exhibit promising mechanical properties that are potential materials for the aeronautical and automotive industries. In this study,...     

Effect of Heat Treatment on Dendritic Segregation and High-Temperature Strength of Single Crystals of Ni3Al-Base Rhenium-Alloyed Intermetallic Alloys

Metal Science and Heat Treatment - The nature of stability of dendritic microsegregation of rhenium in single crystals of intermetallic (γ′ + γ) alloys based on γ′-Ni3Al...