Use of steel and tantalum apparatus for molten Cd-Mg-Zn alloys

Steel and tantalum apparatus contains various ternary alloys of cadmium, zinc, and magnesium used in pyrochemical processes for the recovery of uranium-base reactor fuels. These materials exhibit good corrosion resistance at the high temperatures necessary for fuel separation in liquid metal-molten salt solvents

Study made of resistance of stainless steels to zinc-vapor corrosion

Study of the corrosion resistance of several stainless steels to zinc vapor revealed that some stainless steels could be employed for use in zinc processing equipment housings or vapor lines

The Vietnamese Shrimpers of Texas:Salvaging a Sinking Industry (Comment)

Vietnamese shrimpers working in Texas fear that the recent implementation of maritime security laws will force them to abandon their livelihoods.' At issue are laws that require the captains of U.S. flagships, and 75 percent of their crew, be American citizens. The shrimpers face other challenges, including increased environmental regulations that restrict when and where they can trawl. Despite the bleak forecast, the Vietnamese have endured numerous challenges throughout their 30 year history trawling Texas waters. I argue that the Texas shrimping industry is worth salvaging. As a gateway industry for unskilled immigrants, shrimping in Texas provides a reputable starting position in the quest for the American dream. Both the federal and state governments can help by addressing the most pressing issues through legislation

NASA advanced space photovoltaic technology-status, potential and future mission applications

The NASA program in space photovoltaic research and development encompasses a wide range of emerging options for future space power systems, and includes both cell and array technology development. The long range goals are to develop technology capable of achieving 300 W/kg for planar arrays, and 300 W/sq m for concentrator arrays. InP and GaAs planar and concentrator cell technologies are under investigation for their potential high efficiency and good radiation resistance. The Advanced Photovoltaic Solar Array (APSA) program is a near term effort aimed at demonstrating 130 W/kg beginning of life specific power using thin (62 micrometer) silicon cells. It is intended to be technology transparent to future high efficiency cells and provides the baseline for development of the 300 W/kg array

Pyroxene equilibration temperatures in metamorphosed ordinary chondrites

Ordinary chondrites are divided into petrographic types based on observed mineralogical and textural properties consistent with progressive thermal metamorphism from low grade (type 3) to high (type 7). Regardless of the exact cause of the metamorphism, higher-type chondrites should retain information concerning peak temperatures reached and for what duration. Using the two-pyroxene geothermometer of Lindsley, we have calculated the equilibration temperatures for 26H, L and LL type 5 and 6 ordinary chondrites, to investigate the relative peak temperatures and equilibration-states reached by these various meteorite classes. The Lindsley thermometer relies on a detailed accounting of non-quadrilateral components in pyroxenes, whose recalculated compositions are then plotted onto an empirically-derived polythermal diagram from which temperatures can be interpolated. The reported uncertainty of this method is plus or minus 50 C; in addition, close spacing of isotherms on the graph (particularly for orthopyroxene compositions) increase this uncertainty. We have parameterized the Lindsley polythermal quadrilateral for 1 atm pressure (less than 2 bar), and interpreted recalculated coordinates directly in terms of 25 C temperature intervals. Meteorites selected for this study include both relatively shocked and unshoked specimens; heavily weathered or visibly brecciated specimens were avoided. Temperatures were calculated from orthopyroxene (opx) and clinopyroxene (cpx) analyses within one relative percent of ideal sums and stoichiometry. Histograms summarizing the calculated temperatures for type 5 and 6 ordinary chondrites are shown

Epigenetic Modifications of the PGC-1α Promoter during Exercise Induced Expression in Mice

The transcriptional coactivator, PGC-1α, is known for its role in mitochondrial biogenesis. Although originally thought to exist as a single protein isoform, recent studies have identified additional promoters which produce multiple mRNA transcripts. One of these promoters (promoter B), approximately 13.7kb upstream of the canonical PGC-1α promoter (promoter A), yields alternative transcripts present at levels much lower than the canonical PGC-1α mRNA transcript. In skeletal muscle, exercise resulted in a substantial, rapid increase of mRNA of these alternative PGC-1α transcripts. Although the β2-adrenergic receptor was identified as a signaling pathway that activates transcription from PGC-1α promoter B, it is not yet known what molecular changes occur to facilitate PGC-1α promoter B activation following exercise. We sought to determine whether epigenetic modifications were involved in this exercise response in mouse skeletal muscle. We found that DNA hydroxymethylation correlated to increased basal mRNA levels from PGC-1α promoter A, but that DNA methylation appeared to play no role in the exercise-induced activation of PGC-1α promoter B. The level of the activating histone mark H3K4me3 increased with exercise 2–4 fold across PGC- 1α promoter B, but remained unaltered past the canonical PGC-1α transcriptional start site. Together, these data show that epigenetic modifications partially explain exercise-induced changes in the skeletal muscle mRNA levels of PGC-1α isoforms

Rapid Publication The Transmembrane pH Gradient Drives Uphill Folate Transport in Rabbit Jejunum Direct Evidence for Folate/Hydroxyl Exchange in Brush Border Membrane Vesicles

Abstract In rabbit jejunal, but not ileal brush border membrane vesicles, an outwardly directed OH-gradient (pH 7.7 inside, pH 5.5 outside) markedly stimulated the initial velocity of folate (0.1 tiM) uptake compared with uptake in the absence of a pH gradient. Under pH gradient conditions, folate was transiently accumulated at a concentration four times that found at equilibrium (overshoot), implying uphill transport of the vitamin. Equilibrium folate uptake was inversely proportional to medium osmolality, suggesting uptake into an osmotically sensitive space. pH gradient-stimulated folate uptake was markedly reduced by inhibitors of anion exchange (4,4'-diisothiocyano-2,2'-disulfonic acid stilbene; 4-acetamido-4-isothiocyanostilbene-2,2'-disulfonic acid; furosemide), and was saturable (folate K., = 0.19±0.02 gsM; V, = 12.8±0.4 pmol -mg protein-' . min-). Imposition of an inside-positive electrical potential did not stimulate folate uptake, suggesting that stimulation by a pH gradient was not due to an induced electrical potential. In contrast, an inwardly directed Na' or K' gradient did not stimulate folate uptake. These findings provide evidence for a carrier on the jejunal brush border membrane that mediates folate/OH-exchange (or HW/folate co-transport), and are consonant with the known presence of an outwardly directed OH-gradient in vivo (brush border acid microclimate), an acidic pH optimum for intestinal folate uptake, and the primary role of the jejunum in folate absorption

Coordination cages as permanently porous ionic liquids

Porous materials are widely used in industry for applications that include chemical separations and gas scrubbing. These materials are typically porous solids, although the liquid state can be easier to manipulate in industrial settings. The idea of combining the size and shape selectivity of porous domains with the fluidity of liquids is a promising one and porous liquids composed of functionalized organic cages have recently attracted attention. Here we describe an ionic-liquid, porous, tetrahedral coordination cage. Complementing the gas binding observed in other porous liquids, this material also encapsulates non-gaseous guests—shape and size selectivity was observed for a series of isomeric alcohols. Three gaseous chlorofluorocarbon guests, trichlorofluoromethane, dichlorodifluoromethane and chlorotrifluoromethane, were also shown to be taken up by the liquid coordination cage with an affinity that increased with their size. We hope that these findings will lead to the synthesis of other porous liquids whose guest-uptake properties may be tailored to fulfil specific functions