Processing and Composition Effects on the Fracture Behavior of Spray-Formed 7XXX Series Al Alloys

The fracture properties of high-strength spray-formed Al alloys were investigated, with consideration of the effects of elemental additions such as zinc,manganese, and chromium and the influence of the addition of SiC particulate. Fracture resistance values between 13.6 and 25.6 MPa (m)1/2 were obtained for the monolithic alloys in the T6 and T7 conditions, respectively. The alloys with SiC particulate compared well and achieved fracture resistance values between 18.7 and 25.6 MPa (m)1/2. The spray-formed materials exhibited a loss in fracture resistance (KI) compared to ingot metallurgy 7075 alloys but had an improvedperformance compared to high-solute powder metallurgy alloys of similar composition. Characterization of the fracture surfaces indicated a predominantly intergranular decohesion, possibly facilitated by the presence of incoherent particles at the grain boundary regions and by the large strength differentialbetween the matrix and precipitate zone. It is believed that at the slip band-grain boundary intersection, particularly in the presence of large dispersoids and/or inclusions, microvoid nucleation would be significantly enhanced. Differences in fracture surfaces between the alloys in the T6 and T7 condition were observed and are attributed to inhomogeneous slip distribution, which results in strain localization at grain boundaries. The best overall combination of fracture resistance properties were obtained for alloys with minimum amounts of chromium and manganese additions.

Finnish Miners versus Ivy League Capitalists

Finnish immigrants were recruited to work in the copper mines of Michigan by Boston capitalists intimately associated with Harvard. Boston capitalists defined the culture of capitalism in the United States. They extended their culture across the continent as they acquired mines and railroads. Finnish workers encountered Ivy League capitalism in Michigan, Minnesota, Idaho, Montana, Wyoming, Colorado, Utah and Arizona—often with the same interrelated group of capitalists. The two groups continually met in explosive confrontations in Montana, Michigan, Minnesota, and Arizona. To the Ivy League capitalists, Finns were terrorists who threatened the American social order. For the Finns, it was a war for social justice. In my presentation, I will trace the experience of Finnish workers in corporations controlled by Ivy League capitalists from the first strike at Calumet & Hecla in 1873 to the Red Scare of 1919-1921.

The Effect of Cobalt Upon Current Efficiency in the Electrolysis of Zinc Sulphate Solutions

The detrimental effect of the presence of cobalt upon the current efficiency, in the commercial production of zinc by electrolysis, has been recognized for some time. Most authorities differ upon the maximum amount of cobalt allowable. This is due to the fact that the presence of other impurities either increases or diminishes the detrimental effects of the cobalt. The following tests were made with the object in view of ascertaining the relation, if any, between the amount of cobalt present and the current efficiency during the electrolysis of an otherwise pure zinc sulfate solution. The results obtained from these observations indicate that there is little apparent relation between the cobalt concentration of a given solution of zinc sulfate and the current efficiency that may be obtained on the electrolysis of that solution. For certain cobalt concentrations, however, it was noted that the time factor played an important part.

Geology of the Tuxedo Mining District

The Tuxedo mining district lies fifteen miles west of Butte on the south east end of Deer Lodge valley. Prospecting and mining has been carried on in this district for about 20 years. As a result many pits have been dug, several adits have been driven, and two or three shallow shafts have been sunk.

Geology and Ore Deposits of the Salt Chuck-Rush and Brown Mine Area Prince of Wales Island, Alaska

The Salt Chuck, Rush and Brown, and adjacent mines and claims form an area of approximately 15 square miles near the head of Kasaan Bay about 10 miles northwest of the village of Kasaan on Prince of Wales Island in southeastern Alaska. It is an area of moderate relief in which the hills rise from the water’s edge to heights of some 500 feet. Most of the area is covered with dense vegetation and muskeg.

A Geological Report on Several Localities in the Northwestern Tobacco Root Mountains

To better acquaint seniors in Geology and mining with actual field practice, the Montana School of Mines offer a course in Geologic Field Mapping, during the three weeks preceding the opening of the fall semester. The first two weeks are spent in actual field mapping of the geologic formations near Whitehall, Montana, while the third week is spent back on the campus compiling data and finishing maps started in the field.

The role of zinc dynamics in growth hormone secretion

Human growth hormone (GH) causes a variety of physiological and metabolic effects in humans and plays a pivotal role in postnatal growth. In somatotroph cells of the anterior pituitary, GH is stored in concentrated forms in secretory granules to be rapidly released upon GH-releasing hormone stimulation. During the process of secretory granule biogenesis, self-association of GH occurs in the compartments of the early secretory pathway (endoplasmic reticulum and Golgi complex). Since this process is greatly facilitated by the presence of zinc ions, it is of importance to understand the potential role of zinc transporters that participate in the fine-tuning of zinc homeostasis and dynamics, particularly in the early secretory pathway. Thus, the role of zinc transporters in supplying the secretory pathway with the sufficient amount of zinc required for the biogenesis of GH-containing secretory granules is essential for normal secretion. This report, illustrated by a clinical case report on transient neonatal zinc deficiency, focuses on the role of zinc in GH storage in the secretory granules and highlights the role of specific zinc transporters in the early secretory pathway.

Recent Increases in Atmospheric Concentrations of Bi, U, Cs, S and Ca from a 350-Year Mount Everest Ice Core Record

High-resolution major and trace elements (Sr, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, U, Tl, Al, S, Ca, Ti, V, Cr, Mn, Fe, and Co) quantified in a Mount Everest ice core ( 6518 m above sea level) spanning the period 1650-2002 AD provides the first Asian record of trace element concentrations from the pre-industrial era, and the first continuous high-resolution Asian record from which natural baseline concentrations and subsequent changes due to anthropogenic activities can be examined. Modern concentrations of most elements remain within the pre-industrial range; however, Bi, U, and Cs concentrations and their enrichment factors (EF) have increased since the similar to 1950s, and S and Ca concentrations and their EFs have increased since the late 1980s. A comparison of the Bi, U, Cs, S, and Ca data with other ice core records and production data indicates that the increase in atmospheric concentrations of trace elements is widespread, but that enrichment varies regionally. Likely sources for the recent enrichment of these elements include mining, metal smelting, oil and coal combustion, and end uses for Bi, and mining and refinement for U and Cs. The source of the synchronous enrichment of Ca and S is less certain, but may be related to land use and environmental change.

Development of the First Fluorescence Screening Assay for the SLC39A2 Zinc Transporter.

Zinc is an essential micronutrient that is crucial for many vital cellular functions such as DNA and protein synthesis, metabolism, and intracellular signaling. Therefore, the intracellular zinc concentration is tightly regulated by zinc transporters and zinc-binding proteins. The members of the SCL39 transporter family transport zinc into the cytosol. The SLC39A2 (hZIP2) protein is highly expressed in prostate epithelial cells and was found to be involved in prostate cancer development. Thus far, there is no specific modulator available for the SLC39 transporters. The aim of this study was to develop a screening assay for compound screening targeting hZIP2. Employing the pIRES2-DsRed Express 2 bicistronic vector, we detected human ZIP2 expression at the plasma membrane in transiently transfected HEK293 cells. Using the FLIPR Tetra fluorescence plate reader, we demonstrated that ZIP2 transports Cd(2+) with an apparent Km value of 53.96 nM at an extracellular pH of 6.5. The cadmium influx via hZIP2 was inhibited by zinc in a competitive manner. We found that hZIP2 activity can be measured using cadmium in the range of 0.1 to 10 µM with our assay. In summary, for the first time we developed an assay for human ZIP2 that can be adapted to other zinc transporters.

Vegetación bioindicadora de metales pesados en un sistema semiárido

Evaluar la contaminación por metales pesados en los ecosistemas permite conocer la capacidad bioindicativa de especies vegetativas. El objetivo fue determinar la concentración de metales pesados en Prosopis laevigata, Acacia spp. y Schinus molle bajo el efecto de usos suelo y temporalidad. El área se sitúa en la colindancia de los Municipios de Soledad de Graciano Sánchez y San Luis Potosí fragmentada por usos de suelo: agropecuario, comercio y servicios, residencial urbano y minero. Fueron tomadas muestras de hojas de las tres especies en las estaciones de verano, otoño, invierno y primavera y se evaluó la concentración de metales pesados a través de la técnica de ICP-MS. Los análisis estadísticos indicaron niveles de Aluminio (Al) > Cinc (Zn) > Plomo (Pb) > Cobre (Cu) > Titanio (Ti) > Vanadio (V) > Arsénico (As) > Cromo (Cr) > Cadmio (Cd) > Cobalto (Co). Los elementos Al, As, Cd, Cr, Pb y Ti presentaron niveles por encima del umbral normal en vegetación. El uso de suelo tuvo efecto significativo con Al, Ti, Cd, As y Pb; los árboles ubicados en los usos de suelo minero, comercio y servicios tuvieron la mayor concentración. La especie tuvo efecto significativo con Al y Pb siendo Acacia spp. el que presentó la mayor capacidad de acumulación. La temporada del año impactó significativamente en la acumulación de As, Cd, Co, Cu, Cr y Ti en las tres especies. La dinámica antropogénica de los diferentes usos de suelo genera partículas y residuos con metales pesados impactando en la disponibilidad y acumulación en las especies evaluadas. Se contribuye a evaluar el impacto ambiental en el sistema fragmentado recomendando dar continuidad a este tipo de estudios.

(Table 2) Concentrations of dissolved Zn, Cd, Pb, and Cu in waters of the Baltic Sea

A method of determination of low concentrations of zinc, cadmium, lead, and copper dissolved in seawater and interstitial water with use of inversion voltammetry with AC solution conditions is described. The optimum conditions for measurements with accumulation on a mercury-film electrode with a silver substrate are presented. Detection limit is 0.2 ?g/l for zinc and 0.05 ?g/l for cadmium, lead, and copper. Large number of determinations can be carried out during expeditions at natural pH of seawater containing these four metals.