Note: This page contains sample records for the topic secondary mineral microtextures from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

The Structures and Microtextures of the Palygorskite–Sepiolite Group Minerals  

Microsoft Academic Search

The essential features of the palygorskite–sepiolite mineral group are (1) continuous tetrahedral basal oxygen planes, (2) an inverted tetrahedral arrangement that forms ribbons of joined pyroxene-like chains, and (3) a discontinuous octahedral sheet. These features are based on palygorskite and sepiolite models only and do not reflect other possible structural variations (e.g. chains that are not pyroxene-like). The palygorskite–sepiolite mineral

Stephen Guggenheim; Mark P. S. Krekeler

2011-01-01

2

Mars weathering analogs - Secondary mineralization in Antarctic basalts  

NASA Technical Reports Server (NTRS)

Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.

Berkley, J. L.

1982-01-01

3

Ion beam microtexturing and enhanced surface diffusion  

NASA Technical Reports Server (NTRS)

Ion beam interactions with solid surfaces are discussed with particular emphasis on microtexturing induced by the deliberate deposition of controllable amounts of an impurity material onto a solid surface while simultaneously sputtering the surface with an ion beam. Experimental study of the optical properties of microtextured surfaces is described. Measurements of both absorptance as a function of wavelength and emissivity are presented. A computer code is described that models the sputtering and ion reflection processes involved in microtexture formation.

Robinson, R. S.

1982-01-01

4

Raman Study of Secondary Minerals in a Recent Lava Tube  

NASA Astrophysics Data System (ADS)

We present here the technical adaptations made for a field use of a laboratory in situ Raman spectrometer, and the characterization of secondary mineral phases growing in a recent, still hot on some spots, lava tube (2007 Piton de la Fournaise).

Guimbretière, G.; Canizarès, A.; Finizola, A.; Delcher, E.; Raimboux, N.; Veron, E.; Simon, P.; Devouard, B.; Bertil, A.

2014-06-01

5

Bisphosphonates do not alter the rate of secondary mineralization  

SciTech Connect

Bisphosphonates function to reduce bone turnover, which consequently increases the mean degree of tissue mineralization at an organ level. However, it is not clear if bisphosphonates alter the length of time required for an individual bone-modeling unit (BMU) to fully mineralize. We have recently demonstrated that it takes {approx}350 days (d) for normal, untreated cortical bone to fully mineralize. The aim of this study was to determine the rate at which newly formed trabecular BMUs become fully mineralized in rabbits treated for up to 414 d with clinical doses of either risedronate (RIS) or alendronate (ALN). Thirty-six, 4-month old virgin female New Zealand white rabbits were allocated to RIS (n = 12; 2.4 {micro}g/kg body weight), ALN (n = 12; 2.4 {micro}g/kg body weight), or volume-matched saline controls (CON; n = 12). Fluorochrome labels were administered at specific time intervals to quantify the rate and level of mineralization of trabecular bone from the femoral neck (FN) by Fourier transform infrared microspectroscopy (FTIRM). The organic (collagen) and inorganic (phosphate and carbonate) IR spectral characteristics of trabecular bone from undecalcified 4 micron thick tissue sections were quantified from fluorescently labels regions that had mineralized for 1, 8, 18, 35, 70, 105, 140, 210, 280, and 385 d (4 rabbits per time point and treatment group). All groups exhibited a rapid increase in mineralization over the first 18 days, the period of primary mineralization, with no significant differences between treatments. Mineralization continued to increase, at a slower rate up, to 385 days (secondary mineralization), and was not different among treatments. There were no significant differences between treatments for the rate of mineralization within an individual BMU; however, ALN and RIS both increased global tissue mineralization as demonstrated by areal bone mineral density from DXA. We conclude that increases in tissue mineralization that occur following a period of bisphosphonate treatment is a function of the suppressed rate of remodeling that allows for a greater number of BMUs to obtain a greater degree of mineralization.

Fuchs R. K.; Miller L.; Faillace M.E.; Allen M.R.; Phipps R.J. and Burr D.B.

2011-05-18

6

Bisphosphonates do not Alter the Rate of Secondary Mineralization  

SciTech Connect

Bisphosphonates function to reduce bone turnover, which consequently increases the mean degree of tissue mineralization at an organ level. However, it is not clear if bisphosphonates alter the length of time required for an individual bone-modeling unit (BMU) to fully mineralize. We have recently demonstrated that it takes {approx}350 days (d) for normal, untreated cortical bone to fully mineralize. The aim of this study was to determine the rate at which newly formed trabecular BMUs become fully mineralized in rabbits treated for up to 414 d with clinical doses of either risedronate (RIS) or alendronate (ALN). Thirty-six, 4-month old virgin female New Zealand white rabbits were allocated to RIS (n=12; 2.4 {mu}g/kg body weight), ALN (n=12; 2.4 {mu}g/kg body weight), or volume-matched saline controls (CON; n=12). Fluorochrome labels were administered at specific time intervals to quantify the rate and level of mineralization of trabecular bone from the femoral neck (FN) by Fourier transform infrared microspectroscopy (FTIRM). The organic (collagen) and inorganic (phosphate and carbonate) IR spectral characteristics of trabecular bone from undecalcified 4 micron thick tissue sections were quantified from fluorescently labels regions that had mineralized for 1, 8, 18, 35, 70, 105, 140, 210, 280, and 385 d (4 rabbits per time point and treatment group). All groups exhibited a rapid increase in mineralization over the first 18 days, the period of primary mineralization, with no significant differences between treatments. Mineralization continued to increase, at a slower rate up, to 385 days (secondary mineralization), and was not different among treatments. There were no significant differences between treatments for the rate of mineralization within an individual BMU; however, ALN and RIS both increased global tissue mineralization as demonstrated by areal bone mineral density from DXA. We conclude that increases in tissue mineralization that occur following a period of bisphosphonate treatment is a function of the suppressed rate of remodeling that allows for a greater number of BMUs to obtain a greater degree of mineralization.

R Fuchs; M Faillace; M Allen; R Phipps; L Miller; D Burr

2011-12-31

7

Secondary sulfate minerals from Alum Cave Bluff: Microscopy and microanalysis  

SciTech Connect

Microcrystals of secondary sulfate minerals from Alum Cave Bluff, Great Smoky Mountains National Park, were examined by scanning electron microscopy and identified by X-ray fluorescence (XRF) in the SEM. Among the samples the author discovered three new rare-earth sulfates: coskrenite-(Ce), levinsonite-(Y), and zugshunstite-(Ce). Other minerals illustrated in this report include sulfur, tschermigite, gypsum, epsomite, melanterite, halotrichite, apjohnite, jarosite, slavikite, magnesiocopiapite, and diadochite. Additional specimens whose identification is more tentative include pickeringite, aluminite, basaluminite, and botryogen. Alum Cave is a ``Dana locality`` for apjohnite and potash alum, and is the first documented North American occurrence of slavikite.

Lauf, R.J.

1997-07-01

8

Origin of secondary sulfate minerals on active andesitic stratovolcanoes  

USGS Publications Warehouse

Sulfate minerals in altered rocks on the upper flanks and summits of active andesitic stratovolcanoes result from multiple processes. The origin of these sulfates at five active volcanoes, Citlalte??petl (Mexico), and Mount Adams, Hood, Rainier, and Shasta (Cascade Range, USA), was investigated using field observations, petrography, mineralogy, chemical modeling, and stable-isotope data. The four general groups of sulfate minerals identified are: (1) alunite group, (2) jarosite group, (3) readily soluble Fe- and Al-hydroxysulfates, and (4) simple alkaline-earth sulfates such as anhydrite, gypsum, and barite. Generalized assemblages of spatially associated secondary minerals were recognized: (1) alunite+silica??pyrite??kaolinite?? gypsum??sulfur, (2) jarosite+alunite+silica; (3) jarosite+smectite+silica??pyrite, (4) Fe- and Al-hydroxysulfates+silica, and (5) simple sulfates+silica??Al-hydroxysulfates??alunite. Isotopic data verify that all sulfate and sulfide minerals and their associated alteration assemblages result largely from the introduction of sulfur-bearing magmatic gases into meteoric water in the upper levels of the volcanoes. The sulfur and oxygen isotopic data for all minerals indicate the general mixing of aqueous sulfate derived from deep (largely disproportionation of SO2 in magmatic vapor) and shallow (oxidation of pyrite or H2S) sources. The hydrogen and oxygen isotopic data of alunite indicate the mixing of magmatic and meteoric fluids. Some alunite-group minerals, along with kaolinite, formed from sulfuric acid created by the disproportionation of SO2 in a condensing magmatic vapor. Such alunite, observed only in those volcanoes whose interiors are exposed by erosion or edifice collapse, may have ??34S values that reflect equilibrium (350??50 ??C) between aqueous sulfate and H2S. Alunite with ??34S values indicating disequilibrium between parent aqueous sulfate and H2S may form from aqueous sulfate created in higher level low-temperature environments in which SO2 is scrubbed out by groundwater or where H2S is oxidized. Jarosite-group minerals associated with smectite in only slightly altered volcanic rock are formed largely from aqueous sulfate derived from supergene oxidation of hydrothermal pyrite above the water table. Soluble Al- and Fehydroxysulfates form in low-pH surface environments, especially around fumaroles, and from the oxidation of hydrothermal pyrite. Anhydrite/gypsum, often associated with native sulfur and occasionally with small amounts of barite, also commonly form around fumaroles. Some occurrences of anhydrite/gypsum may be secondary, derived from the dissolution and reprecipitation of soluble sulfate. Edifice collapse may also reveal deep veins of anhydrite/gypsum??barite that formed from the mixing of saline fluids with magmatic sulfate and dilute meteoric water. Alteration along structures associated with both hydrothermal and supergene sulfates, as well as the position of paleo-water tables, may be important factors in edifice collapse and resulting debris flows at some volcanoes. ?? 2004 Elsevier B.V. All rights reserved.

Zimbelman, D. R.; Rye, R. O.; Breit, G. N.

2005-01-01

9

Microtextured Silicon Surfaces for Detectors, Sensors & Photovoltaics  

SciTech Connect

With support from this award we studied a novel silicon microtexturing process and its application in silicon-based infrared photodetectors. By irradiating the surface of a silicon wafer with intense femtosecond laser pulses in the presence of certain gases or liquids, the originally shiny, flat surface is transformed into a dark array of microstructures. The resulting microtextured surface has near-unity absorption from near-ultraviolet to infrared wavelengths well below the band gap. The high, broad absorption of microtextured silicon could enable the production of silicon-based photodiodes for use as inexpensive, room-temperature multi-spectral photodetectors. Such detectors would find use in numerous applications including environmental sensors, solar energy, and infrared imaging. The goals of this study were to learn about microtextured surfaces and then develop and test prototype silicon detectors for the visible and infrared. We were extremely successful in achieving our goals. During the first two years of this award, we learned a great deal about how microtextured surfaces form and what leads to their remarkable optical properties. We used this knowledge to build prototype detectors with high sensitivity in both the visible and in the near-infrared. We obtained room-temperature responsivities as high as 100 A/W at 1064 nm, two orders of magnitude higher than standard silicon photodiodes. For wavelengths below the band gap, we obtained responsivities as high as 50 mA/W at 1330 nm and 35 mA/W at 1550 nm, close to the responsivity of InGaAs photodiodes and five orders of magnitude higher than silicon devices in this wavelength region.

Carey, JE; Mazur, E

2005-05-19

10

The role of secondary mineral precipitates on radionuclide sequestration at the Hanford Site  

SciTech Connect

The effects of secondary mineral precipitates on radionuclide sequestration at the Hanford Site were investigated by reacting quartz and Hanford sediment (Warden Soil) with caustic solution of high ionic strength (2 M NaNO3), high pH (~13), high temperature (~90oC), and dissolved Al(0.01 M Al(NO3)3). Continuous Si dissolution and concomitant secondary mineral precipitation were the principal reactions observed. Nitrate-cancrinite was the dominant secondary precipitate on mineral surfaces after 3-10 days reaction time. The presence of dissolved Al in the simulated tank fluid was found to depress the net Si dissolved concentration. Based on batch equilibrium sorption results, secondary precipitates (cancrinite) at the primary mineral surfaces enhanced the sorption capacity of typical Hanford sediment for radionuclides of major concern at the Hanford Site such as 129I, 79Se, 99Tc, and 90Sr.

Um, Wooyong; Serne, R. Jeffrey; Yabusaki, Steven B.; Freedman, Vicky L.; Samson, Sherry D.; Nagy, Kathryn L.

2004-06-27

11

The Chronology of Asteroid Accretion, Differentiation, and Secondary Mineralization  

NASA Technical Reports Server (NTRS)

We evaluate initial (Al-26/Al-27)(sub I), (Mn-53/Mn-55)(sub I), (Hf-182/Hf-180)(sub I), and Pb-207/Pb-206 ages for igneous differentiated meteorites and chondrules from ordinary chondrites for consistency with radioactive decay of the parent nuclides within a common, closed isotopic system, i.e., the early solar nebula. We find that the relative abundances of Al-26, Mn-53, and Hf-182, here denoted by I(Al)(sub CAI, I(Mn)(sub CAI) and I(Hf)(sub CAI), are consistent with decay from common initial values for the bulk solar system. I(Mn)(sub CAI) and I(Hf)(sub CAI) = 9.1+/-1.7 x 10(exp -6) and 1.06+/-0.09 x 10(exp -6) respectively, correspond to the canonical value of I(Al)(sub CAI) = 5.1 x 10(exp -5). I(Hf)(sub CAI) thus determined is consistent with I(Hf)(sub CAI) = 1.003+/-0.045 x 10(exp -6) directly determined in separate work. I(Mn)(sub CAI) is within error of the lowest value directly determined for CAI. We suggest that erratically higher values directly determined for CAI in carbonaceous chondrites reflect proton irradiation of unaccreted CAIs by the early Sun after other asteroids destined for melting by Al-26 decay had already accreted. The Mn-53 incorporated within such asteroids would have been shielded from further "local" spallogenic contributions. The relative abundances of the short-lived nuclides are less consistent with the Pb-207/Pb-206 ages of the corresponding materials with the best consistency being obtained between (Hf-182/Hf-180)(sub I) and Pb-207/Pb-206 ages of angrites. (Hf-182/Hf-180)(sub I) decreases with decreasing Pb-207/Pb-206 ages at the rate expected from the 8.90+/-0.09 Ma half-life of Hf-182. However, the model "CAI age" thus determined, T(sub CAI,Mn-W) = 4568.6+/-0.7 Ma, is older than the commonly accepted directly measured value T(sub CAI) = 4567.l+/-0.2 Ma. I(Al)(sub I), and (Mn-53/Mn-55)(sub I) are less consistent with Pb-207/Pb-206 ages, but determine T(sub CAI, Mn-Cr) = 4568.3+/-0.5 Ma relative to I(AI)(sub CAI)= 5.1 x 10(exp -5) and a Pb-207/Pb-206 age of 4558.6 Ma for the LEW86010 angrite. However. the (Mn-53/Mn-55)(sub I) and Pb-207/Pb-206 ages of "intermediate" age D'Orbigny-clan angrites and Asuka 881394 are inconsistent with radioactive decay from CAI values with a Mn-55 half-life of 3.7+/-0.4 Ma. in spite of consistency between (Mn-53/Mn-55)(sub I) and (Al-26/Al-27)(sub I). Nevertheless, it appears that the Mn-Cr method with I(Mn)(sub CAI) = 9.1+/-1.7 x 10(exp -6) can be used to date primary igneous events and also secondary mineralization on asteroid parent bodies. We summarize ages thus determined for igneous events on differentiated asteroids and for carbonate and fayalite formation on carbonaceous asteroids.

Nyquist, L. E.; Kleine, T.; Shih, C.-Y.; Reese, Y. D.

2008-01-01

12

Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths  

NASA Astrophysics Data System (ADS)

In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar-water systems. Speciation and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity-activity diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E. and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona, USA. In Water-Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs, New York. pp. 895-899]. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback between dissolution and precipitation reaction kinetics, which needs to be considered in the interpretation of field based dissolution rates.

Zhu, Chen; Lu, Peng

2009-06-01

13

Geopolymers from Algerian metakaolin. Influence of secondary minerals  

Microsoft Academic Search

The influence of secondary phases (illite, quartz) on the geopolymerization reaction of metakaolin has been investigated by comparing two metakaolins, one prepared from a pure kaolinite and the other from illite- and quartz-containing Algerian kaolin from the Tamazert region, respectively. Geopolymerization was achieved by mixing the metakaolins with an alkaline sodium silicate solution at room temperature and curing at 50 °C.

Fatima Zibouche; Hacène Kerdjoudj; Jean-Baptiste d'Espinose de Lacaillerie; Henri Van Damme

2009-01-01

14

Sorption of trace constituents from aqueous solutions onto secondary minerals. II. Radium  

SciTech Connect

Radium sorption efficiencies as a function of temperature, Ra concentration, and secondary mineral sorbate were determined in a 0.01 M NaCl solution. Radium sorption on a characterized clinoptilolite, montmorillonite, nontronite, opal, silica gel, illite, kaolinite, and glauconite under comparable experimental conditions allowed determination of Ra sorption efficiency curves for each, through use of Freundlich constants, over the same temperature and initial Ra solution concentration range Similar sorption data for U on the same secondary minerals over the same temperatures allowed comparison of sorption efficiencies for Ra and U. Clinoptilolite, illite, and nontronite were the most efficient Ra sorbents, while opal and silica gel were the poorest Ra sorbents. Generally, Ra sorption on secondary minerals was much greater than U sorption under the same experimental conditions. 13 references, 9 figures, 5 tables.

Ames, L.L.; McGarrah, J.E.; Walker, B.A.

1983-01-01

15

Secondary Fe–Mn-oxides in minerals heavily damaged by ?-recoil: possible implications for palaeomagnetism  

Microsoft Academic Search

Sub-micron Fe,Mn-oxides in columbite–tantalite minerals are bound to metamict domains in the host. These nano-oxides are secondary\\u000a minerals as the metamict zones formed through accumulation of damages from ?-recoil, each of which in a small volume destroys\\u000a the crystal lattice of the U and Th bearing columbite–tantalite host. Transmission electron microscope investigations demonstrate\\u000a that the oxides fall in the compositional

Rolf L. Romer; Norbert Nowaczyk; Richard Wirth

2007-01-01

16

The role of intragranular microtextures and microstructures in chemical and mechanical weathering: direct comparisons of experimentally and naturally weathered alkali feldspars  

Microsoft Academic Search

Electron microscopic observations of alkali feldspars from soils show that intragranular microtextures, such as exsolution lamellae, and microstructures, primarily dislocations, are both highly significant determinants of the weathering behaviour of these minerals. In particular, strained structure around intersecting edge dislocations in the plane of exsolution lamellae, ?(601), dissolves at a rate which is orders of magnitude greater than unstrained feldspar,

Martin R Lee; Mark E Hodson; Ian Parsons

1998-01-01

17

Microbial Composition in Decomposing Pine Litter Shifts in Response to Common Soil Secondary Minerals  

NASA Astrophysics Data System (ADS)

A range of environmental and biotic factors have been identified that drive microbial community structure in soils - carbon substrates, redox conditions, mineral nutrients, salinity, pH, and species interactions. However, soil mineralogy has been largely ignored as a candidate in spite of recent studies that indicate that minerals have a substantial impact on soil organic matter stores and subsequent fluxes from soils. Given that secondary minerals and organic colloids govern a soil's biogeochemical activity due to surface area and electromagnetic charge, we propose that secondary minerals are a strong determinant of the communities that are responsible for process rates. To test this, we created three microcosms to study communities during decomposition using pine forest litter mixed with two common secondary minerals in soils (goethite and gibbsite) and with quartz as a control. Changes in bacterial and fungal communities were tracked over the 154-day incubation by pyrosequencing fragments of the bacterial 16S and fungal 18S rRNA genes. Ordination using nonmetric multidimensional scaling showed that bacterial communities separated on the basis of minerals. Overall, a single generalist - identified as an Acidobacteriaceae isolate - dominated all treatments over the course of the experiment, representing roughly 25% of all communities. Fungal communities discriminated between the quartz control alone and mineral treatments as a whole. Again, several generalists dominated the community. Coniochaeta ligniaria dominated communities with abundances ranging from 29 to 40%. The general stability of generalist populations may explain the similarities between treatment respiration rates. Variation between molecular fingerprints, then, were largely a function of unique minor members with abundances ranging from 0.01 to 8%. Carbon availability did not surface as a possible mechanism responsible for shifts in fingerprints due to the relatively large mass of needles in the incubation. Other possible mechanisms include the presence of soluble Fe as an alternative energy source in the goethite treatment, the presence of toxic soluble Al in the gibbsite treatment, the loss of available phosphorus in the secondary mineral treatments due to sorption by secondary mineral surfaces, and variations in mineral surfaces as microhabitats. These findings suggest that Al and Fe oxides, such as goethite or gibbsite, are a factor in determining microbial community structure.

Welty-Bernard, A. T.; Heckman, K.; Vazquez, A.; Rasmussen, C.; Chorover, J.; Schwartz, E.

2011-12-01

18

Secondary Minerals in Martian Meteorite MIL 03346 as Detected by Raman Imaging Spectroscopy  

NASA Astrophysics Data System (ADS)

We report a preliminary study of MIL 03346,168 thin section by using the Raman imaging spectroscopy. Our goal is to get the spatial relationship of secondary hydrated minerals in this meteorite and to seek evidences that may hint their origins.

Ling, Z. C.; Wang, A.

2014-06-01

19

Method of making a coating of a microtextured surface  

DOEpatents

A method for conformally coating a microtextured surface. The method includes flash evaporating a polymer precursor forming an evaporate, passing the evaporate to a glow discharge electrode creating a glow discharge polymer precursor plasma from the evaporate, cryocondensing the glow discharge polymer precursor plasma on the microtextured surface and crosslinking the glow discharge polymer precursor plasma thereon, wherein the crosslinking resulting from radicals created in the glow discharge polymer precursor plasma.

Affinito, John D [Tucson, AZ; Graff, Gordon L [West Richland, WA; Martin, Peter M [Kennewick, WA; Gross, Mark E [Pasco, WA; Burrows, Paul E [Kennewick, WA; Sapochak, Linda S [Henderson, NV

2004-11-02

20

The Paris CM chondrite: Secondary minerals and asteroidal processing  

NASA Astrophysics Data System (ADS)

We report a petrographic and mineralogical survey of Paris, a new CM chondrite considered to be the least-altered CM identified so far (Hewins et al.). Compared to other CMs, Paris exhibits (1) a higher concentration of Fe-Ni metal beads, with nickel contents in the range 4.1-8.1 wt%; (2) the systematic presence of thin lamellae and tiny blebs of pentlandite in pyrrhotite grains; and (3) ubiquitous tochilinite/cronstedtite associations with higher FeO/SiO2 and S/SiO2 ratios. In addition, Paris shows the highest concentration of trapped 36Ar reported so far for a CM chondrite (Hewins et al.). In combination with the findings of previous studies, our data confirm the reliability of (1) the alteration sequence based on the chemical composition of tochilinite/cronstedtite associations to quantify the fluid alteration processes and (2) the use of Cr content variability in type II ferroan chondrule olivine as a proxy of thermal metamorphism. In contrast, the scales based on (1) the Fe3+ content of serpentine in the matrix to estimate the degree of aqueous alteration and (2) the chemical composition of Fe-Ni metal beads for quantifying the intensity of the thermal metamorphism are not supported by the characteristics of Paris. It also appears that the amount of trapped 36Ar is a sensitive indicator of the secondary alteration modifications experienced by chondrites, for both aqueous alteration and thermal metamorphism. Considering Paris, our data suggest that this chondrite should be classified as type 2.7 as it suffered limited but significant fluid alteration and only mild thermal metamorphism. These results point out that two separated scales should be used to quantify the degree of the respective role of aqueous alteration and thermal metamorphism in establishing the characteristics of CM chondrites.

Marrocchi, Yves; Gounelle, Matthieu; Blanchard, Ingrid; Caste, Florent; Kearsley, Anton T.

2014-07-01

21

The Paris CM chondrite: Secondary minerals and asteroidal processing  

NASA Astrophysics Data System (ADS)

We report a petrographic and mineralogical survey of Paris, a new CM chondrite considered to be the least-altered CM identified so far (Hewins et al. ). Compared to other CMs, Paris exhibits (1) a higher concentration of Fe-Ni metal beads, with nickel contents in the range 4.1-8.1 wt%; (2) the systematic presence of thin lamellae and tiny blebs of pentlandite in pyrrhotite grains; and (3) ubiquitous tochilinite/cronstedtite associations with higher FeO/SiO2 and S/SiO2 ratios. In addition, Paris shows the highest concentration of trapped 36Ar reported so far for a CM chondrite (Hewins et al. ). In combination with the findings of previous studies, our data confirm the reliability of (1) the alteration sequence based on the chemical composition of tochilinite/cronstedtite associations to quantify the fluid alteration processes and (2) the use of Cr content variability in type II ferroan chondrule olivine as a proxy of thermal metamorphism. In contrast, the scales based on (1) the Fe3+ content of serpentine in the matrix to estimate the degree of aqueous alteration and (2) the chemical composition of Fe-Ni metal beads for quantifying the intensity of the thermal metamorphism are not supported by the characteristics of Paris. It also appears that the amount of trapped 36Ar is a sensitive indicator of the secondary alteration modifications experienced by chondrites, for both aqueous alteration and thermal metamorphism. Considering Paris, our data suggest that this chondrite should be classified as type 2.7 as it suffered limited but significant fluid alteration and only mild thermal metamorphism. These results point out that two separated scales should be used to quantify the degree of the respective role of aqueous alteration and thermal metamorphism in establishing the characteristics of CM chondrites.

Marrocchi, Yves; Gounelle, Matthieu; Blanchard, Ingrid; Caste, Florent; Kearsley, Anton T.

2014-06-01

22

Secondary mineralization and hydrothermal alteration in the Reydarfjordur drill core, eastern Iceland  

NASA Astrophysics Data System (ADS)

Deep crustal drilling in eastern Iceland has allowed study of a fossil hydrothermal system at a constructive plate margin. The drilled sequence consists of partly to completely altered subaerial lava flows, basaltic dikes, and minor clastic material. Alteration and secondary mineralization are most intense in the flow top breccias where water/rock ratios are presumed to have been the highest. In the upper portion of the cored sequence (to a depth of about 1200 m) alteration is characterized by the deposition of clay minerals ± calcite ± quartz ± laumontite into open spaces such as vugs and vesicles. Low-temperature zeolites, such as stilbite, epistilbite, mordenite, and heulandite, are also present but are restricted to the upper 500 m of the drill core. Below 1200 m, alteration is characterized by the dissolution and replacement of both primary minerals and earlier authigenic minerals, followed by partial filling of dissolution cavities. Early mineral assemblages consist of epidote ± quartz ± prehnite ± chlorite ± albite, and a later superimposed assemblage consists of calcite + laumontite ± anhydrite. Authigenic sphene, pyrite, chalcopyrite, pumpellyite, actinolite, and wairakite also occur sporadically in the cored sequence. Secondary mineral assemblages and temperature measurements of fluid inclusions suggest a maximum temperature of alteration of about 300°C. Fluid inclusion compositions indicate that the geothermal fluid was meteoric water with very low salinities and high calcium activities. Iron activities and oxygen fugacities were highest in the deeper portions of the systems. The mineral paragenesis suggests that the fluid composition, temperature, and PCO2 varied significantly with time. The thermal energy for the geothermal system was probably derived from a high-level magma chamber associated with nearby Thingmuli volcano. Local contact metamorphism, indicated by the formation of garnet, occurred during late stage emplacement of dikes into the lava pile. Chlorite ± calcite ± laumontite assemblages were also deposited along subvertical fractures at this time.

Mehegan, James M.; Robinson, Paul T.; Delaney, John R.

1982-08-01

23

Hydrothermal Alteration in the PACMANUS Hydrothermal Field: Implications From Secondary Mineral Assemblages and Mineral Chemistry, OPD Leg 193  

NASA Astrophysics Data System (ADS)

Leg 193 of the Ocean Drilling Program investigated the subsurface nature of the active PACMANUS hydrothermal field in the Manus backarc basin near Papua New Guinea. Drilling in different areas on the felsic neovolcanic Pual Ridge, including the high-temperature black smoker complex of Roman Ruins and the low-temperature Snowcap site with diffusive discharge yielded a complex alteration history with a regional primary alteration being overprinted by a secondary mineralogy. The intense hydrothermal alteration at both sites shows significant differences in the secondary mineralogy. At Roman Ruins, the upper 25 m of hydrothermally altered rocks are characterized by a rapid change from secondary cristobalite to quartz, implying a high temperature gradient. From 10 to 120 mbsf the clay mineralogy is dominated by illite and chlorite. The chlorite formation temperature calculated from oxygen isotope data lies at 250° C in 116 mbsf which is similar to the present fluid outflow temperatures of 240-250° C (Douville et al., 1999, Geochim. Cosmochim. Acta, 63, 627-643). Drilling in the Snowcap field recovered evidence for several stages of hydrothermal alteration. Between 50 and 150 mbsf, cristobalite and chlorite are the most abundant alteration minerals while hydrothermal pyrophyllite becomes abundant in some places At 67 mbsf, the isotopic composition of pyrophyllite gives a temperature for ist formation at 260° C whereas at 77 and 116 mbsf the pyrophyllite displays the highest temperatures of formation (>300° C). These temperatures are close to the maximum measured borehole temperatures of 313° C. The appearance of assemblages of chlorite, chlorite-vermiculite, chlorite-vermiculite-smectite and illite-smectite as well as the local development of corrensite below 150 mbsf suggests that the alteration at Snowcap may be more complex than that beneath Roman Ruins. Detailed geochemical studies of the authigenic clay mineral phases will provide further insights into the chemical changes due to hydrothermal alteration.

Lackschewitz, K. S.; Kummetz, M.; Kummetz, M.; Ackermand, D.; Botz, R.; Devey, C. W.; Singer, A.; Stoffers, P.

2001-12-01

24

Microtextured superhydrophobic surfaces: a thermodynamic analysis.  

PubMed

Superhydrophobic surfaces with a contact angle (CA) larger than 150 degrees have recently attracted great interest in both academic research and practical applications due to their water-repellent or self-cleaning properties. However, thermodynamic mechanisms responsible for the effects of various factors such as surface geometry and chemistry, liquids, and environmental sources have not been well understood. In this study, a pillar microtexture, which has been intensively investigated in experiments, is chosen as a typical example and thermodynamically analyzed in detail. To gain a comprehensive insight into superhydrophobic behavior, the roles of pillar height, width and spacing (or roughness and solid fraction), intrinsic CA, drop size, and vibrational energy are systematically investigated. Free energy (FE) and free energy barrier (FEB) are calculated using a simple and robust model. Based on the calculations of FE and FEB, various CAs, including apparent, equilibrium (stable), advancing and receding CAs, and contact angle hysteresis (CAH) can be determined. Especially, the design of practical superhydrophobic surfaces is emphasized in connection with the transition between noncomposite and composite states; a criterion for judging such transition is proposed. The theoretical results are consistent with the Wenzel's and the Cassie's equations for equilibrium CA values and experimental observations. Furthermore, based on these results and the proposed criterion, some general principles to achieve superhydrophobic performance are suggested. PMID:17331459

Li, W; Amirfazli, A

2007-04-28

25

Secondary mineralization pathways induced by dissimilatory iron reduction of ferrihydrite under advective flow  

NASA Astrophysics Data System (ADS)

Iron (hydr)oxides not only serve as potent sorbents and repositories for nutrients and contaminants but also provide a terminal electron acceptor for microbial respiration. The microbial reduction of Fe (hydr)oxides and the subsequent secondary solid-phase transformations will, therefore, have a profound influence on the biogeochemical cycling of Fe as well as associated metals. Here we elucidate the pathways and mechanisms of secondary mineralization during dissimilatory iron reduction by a common iron-reducing bacterium, Shewanella putrefaciens (strain CN32), of 2-line ferrihydrite under advective flow conditions. Secondary mineralization of ferrihydrite occurs via a coupled, biotic-abiotic pathway primarily resulting in the production of magnetite and goethite with minor amounts of green rust. Operating mineralization pathways are driven by competing abiotic reactions of bacterially generated ferrous iron with the ferrihydrite surface. Subsequent to the initial sorption of ferrous iron on ferrihydrite, goethite (via dissolution/reprecipitation) and/or magnetite (via solid-state conversion) precipitation ensues resulting in the spatial coupling of both goethite and magnetite with the ferrihydrite surface. The distribution of goethite and magnetite within the column is dictated, in large part, by flow-induced ferrous Fe profiles. While goethite precipitation occurs over a large Fe(II) concentration range, magnetite accumulation is only observed at concentrations exceeding 0.3 mmol/L (equivalent to 0.5 mmol Fe[II]/g ferrihydrite) following 16 d of reaction. Consequently, transport-regulated ferrous Fe profiles result in a progression of magnetite levels downgradient within the column. Declining microbial reduction over time results in lower Fe(II) concentrations and a subsequent shift in magnetite precipitation mechanisms from nucleation to crystal growth. While the initial precipitation rate of goethite exceeds that of magnetite, continued growth is inhibited by magnetite formation, potentially a result of lower Fe(III) activity. Conversely, the presence of lower initial Fe(II) concentrations followed by higher concentrations promotes goethite accumulation and inhibits magnetite precipitation even when Fe(II) concentrations later increase, thus revealing the importance of both the rate of Fe(II) generation and flow-induced Fe(II) profiles. As such, the operating secondary mineralization pathways following reductive dissolution of ferrihydrite at a given pH are governed principally by flow-regulated Fe(II) concentration, which drives mineral precipitation kinetics and selection of competing mineral pathways.

Hansel, Colleen M.; Benner, Shawn G.; Neiss, Jim; Dohnalkova, Alice; Kukkadapu, Ravi K.; Fendorf, Scott

2003-08-01

26

Reduction of jarosite by Shewanella oneidensis MR-1 and secondary mineralization  

NASA Astrophysics Data System (ADS)

Jarosite is a common mineral in a variety of environments formed by the oxidation of iron sulfide normally accompanying with the generation of acid mine drainage (AMD) in mining areas or acid rock drainages (ARD) in many localities. Decomposition of jarosite by dissimilatory iron reducing bacteria (DIRB) influences the mobility of many heavy metals generally accommodated in natural jarosite. This study examined the anaerobic reduction of synthesized jarosite by Shewanella oneidensis strain MR-1, a typical facultative bacteria. The release of ferrous and ferric ion, as well as sulfate and potassium, in the inoculated experimental group lasting 80 days is much higher than that in abiotic control groups. The detection of bicarbonate and acetate in experimental solution further confirms the mechanism of microbial reduction of jarosite, in which lactate acts as the electron donor. The produced ferrous iron stimulates the subsequent secondary mineralization, leading to precipitation and transformation of various iron-containing minerals. Green rust and goethite are the intermediate minerals of the microbial reduction process under anoxic conditions, and the end products include magnetite and siderite. In aerobic environments, goethite, magnetite and siderite were also detected, but the contents were relatively lower. While in abiotic experiments, only goethite has been detected as a product. Thus, the microbial reduction and subsequent mineral transformation can remarkably influence the geochemical cycling of iron and sulfur in supergene environments, as well as the mobility of heavy metals commonly accommodated in jarosite.

Bingjie, Ouyang; Xiancai, Lu; Huan, Liu; Juan, Li; Tingting, Zhu; Xiangyu, Zhu; Jianjun, Lu; Rucheng, Wang

2014-01-01

27

Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals  

NASA Astrophysics Data System (ADS)

Structural relations between secondary tungsten minerals with general composition A x[(W,Fe)(O,OH) 3] ·yH 2O are described. Phyllotungstite ( A=predominantly Ca) is hexagonal, a=7.31(3) Å, c=19.55(1) Å, space group P6 3/ mmc. Pittongite, a new secondary tungsten mineral from a wolframite deposit near Pittong in Victoria, southeastern Australia ( A=predominantly Na) is hexagonal, a=7.286(1) Å, c=50.49(1) Å, space group P-6 m2. The structures of both minerals can be described as unit-cell scale intergrowths of (111) py pyrochlore slabs with pairs of hexagonal tungsten bronze (HTB) layers. In phyllotungstite, the (111) py blocks have the same thickness, 6 Å, whereas pittongite contains pyrochlore blocks of two different thicknesses, 6 and 12 Å. The structures can alternatively be described in terms of chemical twinning of the pyrochlore structure on (111) py oxygen planes. At the chemical twin planes, pairs of HTB layers are corner connected as in hexagonal WO 3.

Grey, Ian E.; Birch, William D.; Bougerol, Catherine; Mills, Stuart J.

2006-12-01

28

Secondary mineral phases of metallic lead in soils of shooting ranges from Örebro County, Sweden  

NASA Astrophysics Data System (ADS)

In some countries Pb-containing shotgun pellets have become one of the sources of soil contamination in shooting range areas. Pb pellets from eight shooting ranges in central Sweden were mineralogically analysed and the results show that when the Pb pellets come into contact with soil, about 10% of them are decomposed and transformed into secondary lead minerals as encrustations. The encrustation consists of two concentric rims: a 50 to 150 ?m wide outer rim of hydrocerussite (Pb3(CO3)2(OH)2) and a 10 to 30 ?m wide inner-rim of massicot (PbO). Anglesite (PbSO4) occurs locally in the inner rim. The growing relationship between lead mineral phases suggests that replacement took place. The podzols of the shooting ranges studied are favorable for the formation of lead carbonate. Lead carbonate provides effective controls on the retention of lead in the upper soil layers.

Lin, Zhixun

1996-06-01

29

Secondary sulfate mineralization and basaltic chemistry of craters of the Moon National Monument, Idaho: Potential martian analog  

NASA Astrophysics Data System (ADS)

Craters of the Moon National Monument (COM) basalts offer a reasonable analog to martian basalts, as they have elevated iron concentrations compared to traditional terrestrial analogs. Although secondary sulfate minerals on the evaporitic regions of Mars consist primarily of Mg-, Ca-, and Fe-bearing sulfate minerals, recent orbiter spectroscopic data have suggested Na-sulfate minerals may be present. Secondary minerals in the basaltic caves of COM in southern Idaho are white, efflorescent deposits in small cavities along the cave walls and ceilings and localized mounds on the cave floors. These deposits were examined using X-ray powder diffraction (XRD), X-ray fluorescence spectrometry (XRF), Fourier transform infrared spectrometry (FTIR), and laser desorption Fourier transform ion cyclotron mass spectrometry (LD-FTICRMS). The secondary mineral assemblages were dominated by Na-sulfate minerals (thenardite, mirabilite) with a small fraction of the deposits containing minor concentrations of Na-carbonate minerals. Based on thermodynamic modeling results, formation of the deposits was attributed to leaching of basalt minerals by meteoritic water followed by evaporation of solutions. Such deposits could form under similar conditions in basaltic caves on Mars, making caves an excellent target for astrobiological investigations.

Doc Richardson, C.; Hinman, Nancy W.; McHenry, Lindsay J.; Michelle Kotler, J.; Knipe, Dawn L.; Scott, Jill R.

2012-05-01

30

Control of mineral scale deposition in cooling systems using secondary-treated municipal wastewater.  

PubMed

Secondary-treated municipal wastewater (MWW) is a promising alternative to freshwater as power plant cooling system makeup water, especially in arid regions. A prominent challenge for the successful use of MWW for cooling is potentially severe mineral deposition (scaling) on pipe surfaces. In this study, theoretical, laboratory, and field work was conducted to evaluate the mineral deposition potential of MWW and its deposition control strategies under conditions relevant to power plant cooling systems. Polymaleic acid (PMA) was found to effectively reduce scale formation when the makeup water was concentrated four times in a recirculating cooling system. It was the most effective deposition inhibitor of those studied when applied at 10 mg/L dosing level in a synthetic MWW. However, the deposition inhibition by PMA was compromised by free chlorine added for biogrowth control. Ammonia present in the wastewater suppressed the reaction of the free chlorine with PMA through the formation of chloramines. Monochloramine, an alternative to free chlorine, was found to be less reactive with PMA than free chlorine. In pilot tests, scaling control was more challenging due to the occurrence of biofouling even with effective control of suspended bacteria. Phosphorous-based corrosion inhibitors are not appropriate due to their significant loss through precipitation reactions with calcium. Chemical equilibrium modeling helped with interpretation of mineral precipitation behavior but must be used with caution for recirculating cooling systems, especially with use of MWW, where kinetic limitations and complex water chemistries often prevail. PMID:20851443

Li, Heng; Hsieh, Ming-Kai; Chien, Shih-Hsiang; Monnell, Jason D; Dzombak, David A; Vidic, Radisav D

2011-01-01

31

Secondary-mineral formation during natural weathering of pyroxene: Review and thermodynamic approach  

SciTech Connect

Physical and chemical factors controlling natural weathering processes of pyroxenes through the formation of secondary minerals are reviewed. It has been shown that besides climate, mineralogy, and petrology of parent rocks, mineralogy and structural arrangement of secondary phases rule over the composition of the pyroxene-derived products during increased weathering. Drainage conditions, however, are the most critical factors in constraining weathering paths from the earlier stages of cation-depleted layer-silicate formation to the last stages of goethite/kaolinite formation. A succession of transitional phyllosilicates develops from Mg-endmembers to Fe- or Al-endmembers. The chemistry of natural percolating waters remains poorly known, and local pH and Eh are generally unknown and difficult to measure in situ. Nevertheless these agents should play an important role at the microscale in the formation of weathering products. Therefore, thermodynamic simulation is required for a better understanding of the natural secondary products formed at the expense of pyroxene. In this paper, computerized calculations were used to monitor the theoretical congruent dissolution, without kinetic effects, of a known mixture of minerals with a solution defined by initial pH, O[sub 2], and CO[sub 2] fugacities, temperature, and opening degree of the system. Results of this thermodynamic modeling generally agree with natural weathering paths, as, for example, successive replacements of pyroxene by Fe- and Al-bearing products such as goethite, kaolinite, and smectites. Changes of pO[sub 2] and Al-content strongly control the composition of the clay solid-solution. Consideration of kinetic effects, composition of weathering solutions in the field, and in situ oxygen fugacity measurement should rank high among future research priorities. 57 refs., 11 figs., 4 tabs.

Noack, Y.; Nahon, D.; Michaux, L. (Universite AIX-Marseille III (France)); Colin, F.; Delvigne, J. (ORSTOM, Paris (France))

1993-02-01

32

Lava Cave Microbial Communities Within Mats and Secondary Mineral Deposits: Implications for Life Detection on Other Planets  

PubMed Central

Abstract Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai‘i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai‘i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai‘i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. Key Words: Biosignatures—Astrobiology—Bacteria—Caves—Life detection—Microbial mats. Astrobiology 11, 601–618.

Melim, L.A.; Spilde, M.N.; Hathaway, J.J.M.; Garcia, M.G.; Moya, M.; Stone, F.D.; Boston, P.J.; Dapkevicius, M.L.N.E.; Riquelme, C.

2011-01-01

33

Secondary Mineralization of Components in CV3 Chondrites: Nebular and Asteroidal Models  

NASA Astrophysics Data System (ADS)

Our review of mineralogical variations among CV3 chondrites suggests that all components, chondrules, matrices, and CAIs, were affected by various degrees of secondary mineralization. Chondrules and CAIs are rimmed with fayalitic olivine [1, 2]; metal in all components is oxidized and sulfidized to magnetite, Ni-rich metal and sulfides [3]; silicates in all components are aqueously altered to phyllosilicates [4]; and nepheline, sodalite, wollastonite, and hedenbergite replace primary minerals in CAIs [5]. In those CV3s with altered CAIs, nepheline etc. are also present in chondrule mesostases [6] and in matrices [7]. Correlated occurrences of secondary minerals indicate that they have related origins. CV3 chondrites can be divided into three kinds according to their secondary features. Reduced CV3s (e.g., Efremovka) lack magnetite [8] and show minimal secondary features. Oxidized CV3s [8] generally show all features: those like Mokoia contain minor fayalitic rims, nepheline, etc, whereas those like Allende lack phyllosilicates but contain well developed fayalite rims and abundant nepheline, etc. Allende-like CV3 chondrites also contain abundant plate-like matrix olivine (Fa(sub)45-55). Similarities in chemistry and O isotopic composition and petrographic observations suggest that fayalitic rims and plate-like matrix olivine have related origins [1, 9]. The presence of secondary minerals in all components implies that alteration postdated component formation. The absence of secondary minerals in reduced CV3s indicates that CV3 oxidized formed from CV3 reduced-like material. Oxidized and reduced materials coexist in some breccias indicating a common parent asteroid. Nebular origins are widely accepted for most secondary features. To form fayalitic rims and matrix , Palme and colleagues [10, 11] suggest that chondritic components were briefly exposed to a hot (>1500 K), highly oxidizing nebula with H2O/H2 to about 1. Such an environment could have resulted from vaporization after >1000-fold dust/gas enrichment [11]. Fe-rich olivine will not condense until most Mg has condensed into forsterite [11]. The steep compositional gradients between adjacent fayalite and forsterite limit the duration of fayalite condensation to a period of several hours [2]. There are several inconsistencies in this late-stage evaporation-condensation model. Fayalitic rims occur inside chondrules and formed by alteration, not by condensation. Forsterite and enstatite grains that supposedly condensed from the nebula are absent on chondrule rims and in chondrites. Magnetite, Ni-rich metal and sulfides are present inside matrix olivine, inconsistent with equilibrium calculations. I-Xe data suggest that sodalite formation in Allende lasted for about 10 Myr, which is inconsistent with a nebular origin [12]. Asteroidal alteration is favored for magnetite [3] and required for most phyllosilicates [4]. Asteroidal formation of fayalite [13] was rejected [2], partly because hydrous minerals are absent in Allende. We suggest that Allende-like CV3 chondrites may have formed in an asteroid by aqueous alteration and dehydration; see Krot et al. [this volume] for details. Higher Na and K concentrations in oxidized CV3 chondrites are not inconsistent with asteroidal alteration, as CM2 chondrites show similar heterogeneities. Acknowledgments: This work was supported by NASA grants NAGW-3281 (K. Keil) and 152-11-40-23 (M.E.Z.). References: [1] Peck J. A. and Wood J. A. (1987) GCA, 51, 1503-1510. [2] Hua X. et al. (1988) GCA, 52, 1389-1408. [3] Blum J. D. et al. (1989) GCA, 53, 543-556. [4] Keller L. P. et al. (1994) GCA, 58, 5589-5598. [5] Hashimoto A. and Grosman L. (1987) GCA, 51, 1685-1704. [6] Kimura M. and Ikeda Y. (1992) Proc. Symp. Antarc. Meteorites, 17, 31-33. [7] Peck J. A. (1983) LPS XIV, 373-374. [8] McSween H. Y. (1977) GCA, 41, 1777-1790. [9] Weinbruch S. et al. (1993) GCA, 57, 2649-2661. [10] Palme et al. (1991) Meteoritics, 25, 383. [11] Palme H. and Fegley B. (1991) EPSL, 101, 180-195. [12] Swindle T. D. et al. (1988) GCA, 52, 2215-2227. [13]

Scott, E. R. D.; Krot, A. N.; Zolensky, M. E.

1995-09-01

34

Secondary Fe-Mn-oxides in minerals heavily damaged by alpha-recoil: possible implications for palaeomagnetism  

Microsoft Academic Search

Sub-micron Fe,Mn-oxides in columbite-tantalite minerals are bound to metamict domains in the host. These nano-oxides are secondary minerals as the metamict zones formed through accumulation of damages from alpha-recoil, each of which in a small volume destroys the crystal lattice of the U and Th bearing columbite-tantalite host. Transmission electron microscope investigations demonstrate that the oxides fall in the compositional

Rolf L. Romer; Norbert Nowaczyk; Richard Wirth

2007-01-01

35

Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks  

SciTech Connect

This project, renewal of a previous EMSP project of the same title, is in its first year of funding at the University of Illinois at Chicago. The purpose is to continue investigating rates and mechanisms of reactions between primary sediment minerals found in the Hanford subsurface and leaked waste tank solutions. The goals are to understand processes that result in (1) changes in porosity and permeability of the sediment and resultant changes in flow paths of the contaminant plumes, (2) formation of secondary precipitates that can take up contaminants in their structures, and (3) release of mineral components that can drive redox reactions affecting dissolved contaminant mobility. A post-doctoral scientist, Dr. Sherry Samson, has been hired and two masters of science students are beginning to conduct experimental research. One research project that is underway is focused on measurement of the dissolution rates of plagioclase feldspar in high pH, high nitrate, high Al-bearing solutions characteristic of the BX tank farms. The first set of experiments is being conduced at room temperature. Subsequent experiments will examine the role of temperature because tank solutions in many cases were near boiling when leakage is thought to have occurred and temperature gradients have been observed beneath the SX and BX tank farms. The dissolution experiments are being conducted in stirred-flow kinetic reactors using powdered labradorite feldspar from Pueblo Park, New Mexico.

Nagy, Kathryn L.; Sturchio, Neil C.

2003-06-01

36

Minerals  

NSDL National Science Digital Library

This slide show provides students with basic information on mineralogy. It explains how the term "mineral" is defined, the properties that are used to identify minerals, their importance in daily life, and some general facts. For each identifying property, an example mineral and photograph are provided. Addresses to websites with additional information are also included.

Passow, Michael

37

Preliminary bounds on the water composition and secondary mineral development that may influence the near-field environment.  

National Technical Information Service (NTIS)

The evolution of the water chemistry and secondary mineral development in the vicinity of the near-field of a potential Yucca Mountain high level nuclear waste repository will be controlled by temperature, and interaction of water with rock over time. Thi...

M. Whitbeck W. Glassley

1998-01-01

38

The behaviour of Li and Mg isotopes during primary phase dissolution and secondary mineral formation in basalt  

NASA Astrophysics Data System (ADS)

This study presents lithium (Li) and magnesium (Mg) isotope data from experiments designed to assess the effects of dissolution of primary phases and the formation of secondary minerals during the weathering of basalt. Basalt glass and olivine dissolution experiments were performed in mixed through-flow reactors under controlled equilibrium conditions, at low pH (2-4) in order to keep solutions undersaturated (i.e. far-from equilibrium) and inhibit the formation of secondary minerals. Combined dissolution-precipitation experiments were performed at high pH (10 and 11) increasing the saturation state of the solutions (moving the system closer to equilibrium) and thereby promoting the formation of secondary minerals. At conditions far from equilibrium saturation state modelling and solution stoichiometry suggest that little secondary mineral formation has occurred. This is supported by the similarity of the dissolution rates of basalt glass and olivine obtained here compared to those of previous experiments. The ? 7Li isotope composition of the experimental solution is indistinguishable from that of the initial basalt glass or olivine indicating that little fractionation has occurred. In contrast, the same experimental solutions have light Mg isotope compositions relative to the primary phases, and the solution becomes progressively lighter with time. In the absence of any evidence for secondary mineral formation the most likely explanation for these light Mg isotope compositions is that there has been preferential loss of light Mg during primary phase dissolution. For the experiments undertaken at close to equilibrium conditions the results of saturation state modelling and changes in solution chemistry suggest that secondary mineral formation has occurred. X-ray diffraction (XRD) measurements of the reacted mineral products from these experiments confirm that the principal secondary phase that has formed is chrysotile. Lithium isotope ratios of the experimental fluid become increasingly heavy with time, consistent with previous experimental work and natural data indicating that 6Li is preferentially incorporated into secondary minerals, leaving the solution enriched in 7Li. The behaviour of Mg isotopes is different from that anticipated or observed in natural systems. Similar to the far from equilibrium experiments initially light Mg is lost during olivine dissolution, but with time the ? 26Mg value of the solution becomes increasingly heavy. This suggests either preferential loss of light, and then heavy Mg from olivine, or that the secondary phase preferentially incorporates light Mg from solution. Assuming that the secondary phase is chrysotile, a Mg-silicate, the sense of Mg fractionation is opposite to that previously associated with silicate soils and implies that the fractionation of Mg isotopes during silicate precipitation may be mineral specific. If secondary silicates do preferentially remove light Mg from solution then this could be a possible mechanism for the relatively heavy ? 26Mg value of seawater. This study highlights the utility of experimental studies to quantify the effects of natural weathering reactions on the Li and Mg geochemical cycles.

Wimpenny, Josh; Gíslason, Sigurður R.; James, Rachael H.; Gannoun, Abdelmouhcine; Pogge Von Strandmann, Philip A. E.; Burton, Kevin W.

2010-09-01

39

Effects of salinity and the extent of water on supercritical CO2-induced phlogopite dissolution and secondary mineral formation.  

PubMed

To ensure the viability of geologic CO2 sequestration (GCS), we need a holistic understanding of reactions at supercritical CO2 (scCO2)-saline water-rock interfaces and the environmental factors affecting these interactions. This research investigated the effects of salinity and the extent of water on the dissolution and surface morphological changes of phlogopite [KMg2.87Si3.07Al1.23O10(F,OH)2], a model clay mineral in potential GCS sites. Salinity enhanced the dissolution of phlogopite and affected the location, shape, size, and phase of secondary minerals. In low salinity solutions, nanoscale particles of secondary minerals formed much faster, and there were more nanoparticles than in high salinity solutions. The effect of water extent was investigated by comparing scCO2-H2O(g)-phlogopite and scCO2-H2O(l)-phlogopite interactions. Experimental results suggested that the presence of a thin water film adsorbed on the phlogopite surface caused the formation of dissolution pits and a surface coating of secondary mineral phases that could change the physical properties of rocks. These results provide new information for understanding reactions at scCO2-saline water-rock interfaces in deep saline aquifers and will help design secure and environmentally sustainable CO2 sequestration projects. PMID:21222477

Shao, Hongbo; Ray, Jessica R; Jun, Young-Shin

2011-02-15

40

9 M.y. record of southern Nevada climate from Yucca Mountain secondary minerals  

SciTech Connect

Yucca Mountain, Nevada, is presently the object of intense study as a potential permanent repository for the Nation`s high-level radioactive wastes. The mountain consists of a thick sequence of volcanic tuffs within which the depth to water table ranges from 500 to 700 meters below the land surface. This thick unsaturated zone (UZ), which would host the projected repository, coupled with the present day arid to semi-arid climate, is considered a favorable attribute of the site. Evaluation of the site includes defining the relation between climate variability, as the input function or driver of site- and regional-scale ground-water flow, and the possible future transport and release of radionuclides to the accessible environment. Secondary calcite and opal have been deposited in the UZ by meteoric waters that infiltrated through overlying soils and percolated through the tuffs. The oxygen isotopic composition ({delta}{sup 18}O values) of these minerals reflect contemporaneous meteoric waters and the {delta}{sup 13}C values reflect soil organic matter, and hence the resident plant community, at the time of infiltration. Recent U/Pb age determinations of opal in these occurrences, coupled with the {delta}{sup 13}C values of associated calcite, allow broadbrush reconstructions of climate patterns during the past 9 M.y.

Whelan, J.F.; Moscati, R.J.

1998-12-01

41

Effect of secondary minerals on electrokinetic phenomena during water-rock interaction  

NASA Astrophysics Data System (ADS)

The main geophysical application of spontaneous potentials (SP) anomalies, i.e., electrical signal generated by hydroelectric coupling, is the mapping of hydrothermal zones. Laboratory studies of hydroelectric coupling as a function of temperature are scarce, because of experimental difficulties. Up today experiments carried out by Ishido and Mizutani [1981] with quartz-Al-K-NO3 system for temperatures ranging from 20°C to 80°C are not well understood. In this work, we show that Ishido and Mizutani [1981]'s solutions are oversaturated with aluminium, and that the precipitation of Al(OH)3s is expected. Triple Layer Model (TLM) calculations for a gibbsite-KNO3 system can account for Ishido and Mizutani [1981]'s measurements. These results highlight that (1) the precipitation of a secondary mineral can hide the electrical properties of the primary rock; (2) the geochemical fluid surveys should be taken into account to grasp the interfacial processes (precipitation/dissolution), and to interpret the SP measurements in the field.

Guichet, Xavier; Zuddas, Pierpaolo

2003-07-01

42

Volcanic stratigraphy and secondary mineralization of U. S. G. S. Pucci geothermal test well, Mount Hood, Oregon  

SciTech Connect

Ninety-one sample splits of drill cuttings from approximately 6.1 m intervals in the 610 m hole that was completed in 1979 were provided for this study. An additional 225 sample splits (3.05 m intervals) from 536 m to the bottom of the drill hole at 1220 m were added to the study following the deepening of the drill hole. Stratigraphic and petrologic observations of the cuttings were made. Scanning electron microscope and x-ray diffractometer examinations were made of alteration minerals. The lithology and secondary mineralization are discussed.

Gannett, M.W.; Bargar, K.E.

1981-01-01

43

Sorption and redox reactions of As(III) and As(V) within secondary mineral coatings on aquifer sediment grains.  

PubMed

Important reactive phenomena that affect the transport and fate of many elements occur at the mineral-water interface (MWI), including sorption and redox reactions. Fundamental knowledge of these phenomena are often based on observations of ideal mineral-water systems, for example, studies of molecular scale reactions on single crystal faces or the surfaces of pure mineral powders. Much less is understood about MWI in natural environments, which typically have nanometer to micrometer scale secondary mineral coatings on the surfaces of primary mineral grains. We examined sediment grain coatings from a well-characterized field site to determine the causes of rate limitations for arsenic (As) sorption and redox processes within the coatings. Sediments were obtained from the USGS field research site on Cape Cod, MA, and exposed to synthetic contaminated groundwater solutions. Uptake of As(III) and As(V) into the coatings was studied with a combination of electron microscopy and synchrotron techniques to assess concentration gradients and reactive processes, including electron transfer reactions. Transmission electron microscopy (TEM) and X-ray microprobe (XMP) analyses indicated that As was primarily associated with micrometer- to submicrometer aggregates of Mn-bearing nanoparticulate goethite. As(III) oxidation by this phase was observed but limited by the extent of exposed surface area of the goethite grains to the exterior of the mineral coatings. Secondary mineral coatings are potentially both sinks and sources of contaminants depending on the history of a contaminated site, and may need to be included explicitly in reactive transport models. PMID:24041305

Singer, David M; Fox, Patricia M; Guo, Hua; Marcus, Matthew A; Davis, James A

2013-10-15

44

EBSD analysis of the microtexture of Ba-hexaferrite samples  

NASA Astrophysics Data System (ADS)

The microtexture of differently prepared Ba-hexaferrite samples is investigated by means of electron backscatter diffraction (EBSD). Kikuchi patterns are obtained with a high image quality, enabling a spatial resolution of the EBSD maps of about 20 nm. The spatially highly resolved EBSD mappings provide additional information (individual grain orientation, misorientation angles, grain size distribution) as compared to the standard analysis techniques, which can contribute to an optimization of the growth process. Furthermore, as the crystallographic orientation of each grain is known, an exact analysis of the grain aspect ratio becomes possible which provides further insight to the microstructural dependence of the magnetic properties of ferrites.

Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Chen, Y.; Harris, V. G.

2010-01-01

45

Radionuclide Incorporation in Secondary Crystalline Minerals Resulting from Chemical Weathering of Selected Waste Glasses: Progress Report for Subtask 3d  

SciTech Connect

Experiments were conducted in fiscal year 1998 by Pacific Northwest National Laboratory to evaluate potential incorporation of radionuclides in secondary mineral phases that form from weathering vitrified nuclear waste glasses. These experiments were conducted as part of the Immobilized Low- Activity Waste-Petiormance Assessment (ILAW-PA) to generate data on radionuclide mobilization and transport in a near-field enviromnent of disposed vitrified wastes. An initial experiment was conducted to identify the types of secondary minerals that form from two glass samples of differing compositions, LD6 and SRL202. Chemical weathering of LD6 glass at 90oC in contact with an aliquot of uncontaminated Hanford Site groundwater resulted in the formation of a Crystalline zeolitic mineral, phillipsite. In contrast similar chemical weathering of SRL202 glass at 90"C resulted in the formation of a microcrystalline smectitic mineral, nontronite. A second experiment was conducted at 90"C to assess the degree to which key radionuclides would be sequestered in the structure of secondary crystalline minerals; namely, phillipsite and nontronite. Chemical weathering of LD6 in contact with radionuclide-spiked Hanford Site groundwater indicated that substantial ilactions of the total activities were retained in the phillipsite structure. Similar chemical weathering of SRL202 at 90"C, also in contact with radionuclide-spiked Hanford Site groundwater, showed that significant fractions of the total activities were retained in the nontronite structure. These results have important implications regarding the radionuclide mobilization aspects of the ILAW-PA. Additional studies are required to confkm the results and to develop an improved under- standing of mechanisms of sequestration and attenuated release of radionuclides to help refine certain aspects of their mobilization.

SV Mattigod; DI Kaplan; VL LeGore; RD Orr; HT Schaef; JS Young

1998-10-23

46

Preliminary bounds on the water composition and secondary mineral development that may influence the near-field environment  

SciTech Connect

The evolution of the water chemistry and secondary mineral development in the vicinity of the near-field of a potential Yucca Mountain high level nuclear waste repository will be controlled by temperature, and interaction of water with rock over time. This report describes initial bounds on water composition and secondary mineral development, as a function of time, temperature, and rock type (devitrified, welded tuff and vitrophyre). The code EQ3/6 was used in the calculations, with explicit use of transition state theory models for mineral dissolution rates for the framework minerals of the tuff. Simulations were run for time durations sufficient to achieve steady state conditions. Uncertainty in the calculations, due to uncertainty in the measured dissolution rates, was considered by comparing results in simulations in which rates were varied within the range of known uncertainties for dissolution rate constants. The results demonstrate that the steady state mineralogy and water compositions are relatively insensitive to the rock unit modeled, which is consistent with the fact that the compositions of the rock units in the vicinity if the potential repository are similar, and will tend toward similar thermodynamic free energy minima, for similar rock:water ratios. Significant differences are observed, however, for large differences in rock: water ratios. The rates at which this end point condition are approached are a function of the rate parameters used, and can vary by orders of magnitude.

Whitbeck, M.; Glassley, W.

1998-02-01

47

The role of reaction affinity and secondary minerals in regulating chemical weathering rates at the Santa Cruz Soil Chronosequence, California  

NASA Astrophysics Data System (ADS)

In order to explore the reasons for the apparent discrepancy between laboratory and field weathering rates and to determine the extent to which weathering rates are controlled by the approach to thermodynamic equilibrium, secondary mineral precipitation, and flow rates, a multicomponent reactive transport model (CrunchFlow) was used to interpret soil profile development and mineral precipitation and dissolution rates at the 226 ka Marine Terrace Chronosequence near Santa Cruz, CA. Aqueous compositions, fluid chemistry, transport, and mineral abundances are well characterized [White A. F., Schulz M. S., Vivit D. V., Blum A., Stonestrom D. A. and Anderson S. P. (2008) Chemical weathering of a Marine Terrace Chronosequence, Santa Cruz, California. I: interpreting the long-term controls on chemical weathering based on spatial and temporal element and mineral distributions. Geochim. Cosmochim. Acta72 (1), 36-68] and were used to constrain the reaction rates for the weathering and precipitating minerals in the reactive transport modeling. When primary mineral weathering rates are calculated with either of two experimentally determined rate constants, the nonlinear, parallel rate law formulation of Hellmann and Tisserand [Hellmann R. and Tisserand D. (2006) Dissolution kinetics as a function of the Gibbs free energy of reaction: An experimental study based on albite feldspar. Geochim. Cosmochim. Acta70 (2), 364-383] or the aluminum inhibition model proposed by Oelkers et al. [Oelkers E. H., Schott J. and Devidal J. L. (1994) The effect of aluminum, pH, and chemical affinity on the rates of aluminosilicate dissolution reactions. Geochim. Cosmochim. Acta58 (9), 2011-2024], modeling results are consistent with field-scale observations when independently constrained clay precipitation rates are accounted for. Experimental and field rates, therefore, can be reconciled at the Santa Cruz site. Additionally, observed maximum clay abundances in the argillic horizons occur at the depth and time where the reaction fronts of the primary minerals overlap. The modeling indicates that the argillic horizon at Santa Cruz can be explained almost entirely by weathering of primary minerals and in situ clay precipitation accompanied by undersaturation of kaolinite at the top of the profile. The rate constant for kaolinite precipitation was also determined based on model simulations of mineral abundances and dissolved Al, SiO 2(aq) and pH in pore waters. Changes in the rate of kaolinite precipitation or the flow rate do not affect the gradient of the primary mineral weathering profiles, but instead control the rate of propagation of the primary mineral weathering fronts and thus total mass removed from the weathering profile. Our analysis suggests that secondary clay precipitation is as important as aqueous transport in governing the amount of dissolution that occurs within a profile because clay minerals exert a strong control over the reaction affinity of the dissolving primary minerals. The modeling also indicates that the weathering advance rate and the total mass of mineral dissolved is controlled by the thermodynamic saturation of the primary dissolving phases plagioclase and K-feldspar, as is evident from the difference in propagation rates of the reaction fronts for the two minerals despite their very similar kinetic rate laws.

Maher, Kate; Steefel, Carl I.; White, Art F.; Stonestrom, Dave A.

2009-05-01

48

The role of reaction affinity and secondary minerals in regulating chemical weathering rates at the Santa Cruz Soil Chronosequence, California  

USGS Publications Warehouse

In order to explore the reasons for the apparent discrepancy between laboratory and field weathering rates and to determine the extent to which weathering rates are controlled by the approach to thermodynamic equilibrium, secondary mineral precipitation, and flow rates, a multicomponent reactive transport model (CrunchFlow) was used to interpret soil profile development and mineral precipitation and dissolution rates at the 226 ka Marine Terrace Chronosequence near Santa Cruz, CA. Aqueous compositions, fluid chemistry, transport, and mineral abundances are well characterized [White A. F., Schulz M. S., Vivit D. V., Blum A., Stonestrom D. A. and Anderson S. P. (2008) Chemical weathering of a Marine Terrace Chronosequence, Santa Cruz, California. I: interpreting the long-term controls on chemical weathering based on spatial and temporal element and mineral distributions. Geochim. Cosmochim. Acta 72 (1), 36-68] and were used to constrain the reaction rates for the weathering and precipitating minerals in the reactive transport modeling. When primary mineral weathering rates are calculated with either of two experimentally determined rate constants, the nonlinear, parallel rate law formulation of Hellmann and Tisserand [Hellmann R. and Tisserand D. (2006) Dissolution kinetics as a function of the Gibbs free energy of reaction: An experimental study based on albite feldspar. Geochim. Cosmochim. Acta 70 (2), 364-383] or the aluminum inhibition model proposed by Oelkers et al. [Oelkers E. H., Schott J. and Devidal J. L. (1994) The effect of aluminum, pH, and chemical affinity on the rates of aluminosilicate dissolution reactions. Geochim. Cosmochim. Acta 58 (9), 2011-2024], modeling results are consistent with field-scale observations when independently constrained clay precipitation rates are accounted for. Experimental and field rates, therefore, can be reconciled at the Santa Cruz site. Additionally, observed maximum clay abundances in the argillic horizons occur at the depth and time where the reaction fronts of the primary minerals overlap. The modeling indicates that the argillic horizon at Santa Cruz can be explained almost entirely by weathering of primary minerals and in situ clay precipitation accompanied by undersaturation of kaolinite at the top of the profile. The rate constant for kaolinite precipitation was also determined based on model simulations of mineral abundances and dissolved Al, SiO2(aq) and pH in pore waters. Changes in the rate of kaolinite precipitation or the flow rate do not affect the gradient of the primary mineral weathering profiles, but instead control the rate of propagation of the primary mineral weathering fronts and thus total mass removed from the weathering profile. Our analysis suggests that secondary clay precipitation is as important as aqueous transport in governing the amount of dissolution that occurs within a profile because clay minerals exert a strong control over the reaction affinity of the dissolving primary minerals. The modeling also indicates that the weathering advance rate and the total mass of mineral dissolved is controlled by the thermodynamic saturation of the primary dissolving phases plagioclase and K-feldspar, as is evident from the difference in propagation rates of the reaction fronts for the two minerals despite their very similar kinetic rate laws. ?? 2009 Elsevier Ltd.

Maher, K.; Steefel, C. I.; White, A. F.; Stonestrom, D. A.

2009-01-01

49

Microtextural controls of weathering of perthitic alkali feldspars  

NASA Astrophysics Data System (ADS)

The relationship between the microtexture and dissolution behaviour of fresh, HF acid-etched and naturally weathered alkali feldspar phenocrysts from the Lower Devonian Shap granite has been investigated by SEM and TEM. A novel resin impregnation technique has revealed the three dimensional shape and interconnectivity of etch pits beneath the weathered crystal surface. Further electron microscope work suggests that Shap phenocrysts are representative of the alkali feldspar in the protolith of many soils. Fresh and unweathered Shap feldspars have a complex microtexture, comprising areas of pristine cryptoperthite and lamellar microperthite cross-cut by volumes of microporous altered feldspar or "patch perthites." Cryptoperthites are made up of <75 nm wide albite exsolution lamellae (platelets) in tweed orthoclase, whereas lamellar microperthites contain >75 nm wide albite films. The platelets are coherent, but albite films have numerous edge dislocations along their interface with orthoclase; (001) and (010) cleavage surfaces intersect ˜2-3 edge dislocations/?m 2. In three dimensions, these edge dislocations form an orthogonal net in the "Murchison plane" of easy fracture, close to (601). Patch perthites are irregular, semicoherent to incoherent intergrowths of albite and irregular microcline subgrains, with ˜0.65-0.70 sub-?m to ?m-sized pores/?m 2. Microporous patch perthites form by dissolution-reprecipitation reactions with magmatic or hydrothermal fluids and pores are present before the alkali feldspars enter the weathering regime. Dissolution of Shap feldspars during natural weathering and laboratory acid etching is controlled by their microtexture, especially by dislocations and exsolution lamellae. The core and strain energy associated with dislocation outcrops on (001) and (010) cleavage surfaces promotes rapid dissolution at those sites and formation of nn-sized etch pits after <30 s of laboratory etching with HF acid vapour. With progressive HF etching, crystallographically controlled differences in the reactivity of etch pit walls cause them to expand more rapidly into orthoclase than albite. Naturally weathered feldspars were collected from the glacial erratic boulders, fine gravels surrounding exposed granite surfaces, and from peat soil overlying the granite. During natural weathering, etch pits on microperthites enlarge almost exclusively by dissolution of albite and resin casts demonstrate that they can penetrate ?15 ?m below the cleavage surface, forming an interconnecting, ladder-like grid of submicrometer wide channels in the Murchison plane. Coherent albite platelets and volumes of albite between dislocations in films dissolve uniformly, but faster than orthoclase. This is probably because the albite lamellae have significant elastic coherency strain, but this is much less, per unit volume of albite, than the core and strain energy associated with edge dislocations. Patch perthites etch in HF vapour and weather rapidly in nature to produce a honeycomb-like texture of interconnecting nanometer- to micrometer-sized pits, which nucleate at preexisting micropores or incoherent subgrain boundaries. The size and density of etch pits on microperthite surfaces, which is determined by rates of growth and coalescence, may be a useful progress variable for natural and experimental dissolution. All alkali feldspars are highly heterogeneous materials whose chemical composition and microtexture can vary on a submicrometer scale. These microtextures are critical variables with regard to the origin of surface roughness of fresh and weathered grains, the controls on absolute dissolution rates and why they commonly change over time, the nonlinear variation of dissolution rate with grain size, the ratio of alkali ions released into solution, and disparities between laboratory dissolution rates and those observed in the field.

Lee, Martin R.; Parsons, Ian

1995-11-01

50

Proterozoic polymetamorphism in the Quanji Block, northwestern China: Evidence from microtextures, garnet compositions and monazite CHIME ages  

NASA Astrophysics Data System (ADS)

The Quanji Block, situated close to the triple junction of three major Precambrian terranes in China (i.e., the North China Craton, the Yangtze Block and the Tarim Block), is composed of Precambrian metamorphic crystalline basement and an unmetamorphosed Mesozoic-Paleozoic sedimentary cover; it has been interpreted as a remnant continental fragment. Microtextural relationships, garnet trace element compositions, and monazite CHIME ages in paragneisses, schists and granitic leucosomes show two episodes of regional metamorphism in the Quanji Block basement. The first regional metamorphism and accompaning anatexis took place at ˜1.93 Ga; the second regional metamorphism occurred between ˜1.75 and ˜1.71 Ga. Mineral compositions of the first metamorphism, including those of monazite, were significantly disturbed by the second event. These two regional metamorphic episodes were most likely linked to assembly and breakup of the supercontinent Columbia, respectively.

Wang, Qinyan; Pan, Yuanming; Chen, Nengsong; Li, Xiaoyan; Chen, Haihong

2009-05-01

51

A granulometry and secondary mineral fingerprint of chemical weathering in periglacial landscapes and its application to blockfield origins  

NASA Astrophysics Data System (ADS)

A review of published literature was undertaken to determine if there was a fingerprint of chemical weathering in regoliths subjected to periglacial conditions during their formation. If present, this fingerprint would be applied to the question of when blockfields in periglacial landscapes were initiated. These blocky diamicts are usually considered to represent remnants of regoliths that were chemically weathered under a warm, Neogene climate and therefore indicate surfaces that have undergone only a few metres to a few 10s of metres of erosion during the Quaternary. Based on a comparison of clay and silt abundances and secondary mineral assemblages from blockfields, other regoliths in periglacial settings, and regoliths from non-periglacial settings, a fingerprint of chemical weathering in periglacial landscapes was identified. A mobile regolith origin under, at least seasonal, periglacial conditions is indicated where clay(%) ? 0.5*silt(%) + 8 across a sample batch. This contrasts with a mobile regolith origin under non-periglacial conditions, which is indicated where clay(%) ? 0.5*silt(%) - 6 across a sample batch with clay(%) ? 0.5*silt(%) + 8 in at least one sample. A range of secondary minerals, which frequently includes interstratified minerals and indicates high local variability in leaching conditions, is also commonly present in regoliths exposed to periglacial conditions during their formation. Clay/silt ratios display a threshold response to temperature, related to the freezing point of water, but there is little response to precipitation or regolith residence time. Lithology controls clay and silt abundances, which increase from felsic, through intermediate, to mafic compositions, but does not control clay/silt ratios. Use of a sedigraph or Coulter Counter to determine regolith granulometry systematically indicates lower clay abundances and intra-site variability than use of a pipette or hydrometer. In contrast to clay/silt ratios, secondary mineral assemblages vary according to regolith residence time, temperature, and/or precipitation. A microsystems model is invoked as a conceptual framework in which to interpret the concurrent formation of the observed secondary mineral ranges. According to the fingerprint of chemical weathering in periglacial landscapes, there is generally no evidence of blockfield origins under warm Neogene climates. Nearly all blockfields appear to be a product of Quaternary physical and chemical weathering. A more dominant role for periglacial processes in further bevelling elevated, low relief, non-glacial surface remnants in otherwise glacially eroded landscapes is therefore indicated.

Goodfellow, Bradley W.

2012-12-01

52

Secondary Mineral Deposits and Evidence of Past Seismicity and Heating of the Proposed Repository Horizon at Yucca Mountain, Nevada  

USGS Publications Warehouse

The Drift Degradation Analysis (DDA) (BSC, 2003) for the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, describes model simulations of the effects of pre- and post-closure seismicity and waste-induced heating on emplacement drifts. Based on probabilistic seismic hazard analyses of the intensity and frequency of future seismic events in the region (CRWMS M&O, 1998), the DDA concludes that future seismicity will lead to substantial damage to emplacement drifts, particularly those in the lithophysal tuffs, where some simulations predict complete collapse of the drift walls. Secondary mineral studies conducted by the U.S. Geological Survey since 1995 indicate that secondary calcite and silica have been deposited in some fractures and lithophysal cavities in the unsaturated zone (UZ) at Yucca Mountain during at least the past 10 million years (m.y.), and probably since the tuffs cooled to less than 100?C. Tuff fragments, likely generated by past seismic activity, have commonly been incorporated into the secondary mineral depositional sequences. Preliminary observations indicate that seismic activity has generated few, if any, tuff fragments during the last 2 to 4 m.y., which may be inconsistent with the predictions of drift-wall collapse described in the DDA. Whether or not seismicity-induced tuff fragmentation occurring at centimeter to decimeter scales in the fracture and cavity openings relates directly to failure of tuff walls in the 5.5-m-diameter waste emplacement drifts, the deposits do provide a potential record of the spatial and temporal distribution of tuff fragments in the UZ. In addition, the preservation of weakly attached coatings and (or) delicate, upright blades of calcite in the secondary mineral deposits provides an upper limit for ground motion during the late stage of deposition that might be used as input to future DDA simulations. Finally, bleaching and alteration at a few of the secondary mineral sites indicate that they were subjected to heated gases at approximately the temperatures expected from waste emplacement. These deposits provide at least limited textural and mineralogic analogs for waste-induced, high-humidity thermal alteration of emplacement drift wall rocks.

Whelan, Josheph F.

2004-01-01

53

Applying Micro-Texture to Cast Iron Surfaces to Reduce the Friction Coefficient Under Lubricated Conditions  

Microsoft Academic Search

The tribological properties of cast iron have been investigated to determine the effects of micro-texturing the surfaces.\\u000a The micro-textured surfaces were prepared by shot blasting or milling using a shaper. The surfaces with groove patterns and\\u000a mesh patterns had higher friction coefficients than the flat surfaces. The surfaces with dimpled patterns had lower friction\\u000a coefficients than the flat surfaces. The

Miki Nakano; Atsuko Korenaga; Atsushi Korenaga; Koji Miyake; Takashi Murakami; Yasuhisa Ando; Hatsuhiko Usami; Shinya Sasaki

2007-01-01

54

Using Handheld Raman Spectrometers for Discrimination of Secondary Sulfate Minerals at Outcrops: Potential and Limitations  

NASA Astrophysics Data System (ADS)

In this research we used two lightweight handheld Raman instruments (532 nm and 785 nm) to evaluate the possibility of in-situ identification of sulfates in complicated conditions (outdoor, poorly crystallized mineral phases).

Košek, F.; Culka, A.; Jehli?ka, J.

2014-06-01

55

Attachment point theory revisited: the fouling response to a microtextured matrix.  

PubMed

This paper examines attachment point theory in detail by testing the fouling attachment of several fouling groups to a microtextured matrix. Static bioassays were conducted on polycarbonate plates with nine equal regions, comprising eight scales of microtexture (4-512 microm) and one untextured region. The microtextures examined were continuous sinusoidal ridges and troughs of defined height and width. Attachment over the microtextured plates was examined for the diatom Amphora sp., the green alga Ulva rigida, the red alga Centroceras clavulatum, the serpulid tube worm Hydroides elegans and the bryozoan Bugula neritina. It was found that the size of the microtexture in relation to the size of the settling propagules/larvae was important in the selection of attachment sites. Attachment was generally lower when the microtexture wavelength was slightly smaller than the width of the settling propagules/larvae and increased when the wavelength was wider than their width. The effect of attachment points was weak for small motile microfoulers (Amphora sp. and U. rigida) (7 microm), strong for large macrofouling larvae (H. elegans and B. neritina) (129-321 microm) and non-existent for the non-motile algal spores (C. clavulatum) (37 microm). This study reinforces the potential of using attachment points to develop surfaces with increased fouling resistance or, alternatively, surfaces which promote the attachment of selected target sizes of motile propagules or larvae. PMID:18066730

Scardino, A J; Guenther, J; de Nys, R

2008-01-01

56

Microtextural characteristics of quartz grains transported and deposited by tsunamis and storms  

NASA Astrophysics Data System (ADS)

The complex transport and depositional processes associated with tsunamis and storms and the peculiarities of local inundation present questions associated with the recognition and differentiation of the sedimentary signature of these events. This work presents a study of quartz grains transported and deposited by tsunami and storm waves with the objective of identifying specific microtextural signatures caused by high-energy marine inundations and to correlate them with their principal sedimentary sources. In this empirical study, 1150 quartz grains (78 samples) and their microtextural signatures were observed, analyzed and classified using scanning electron microscope photomicrographs. The results suggest that although no specific microtextural signature is associated with high energy inundations, there are strong increases in the percentage of fresh surfaces and percussion marks when compared with the potential source material. Moreover, tsunami and storm grains present the greatest microtextural variance among all the grains analyzed. Nevertheless, specific local conditions and sediment concentrations constrain the microtextural implications on tsunami or storm grains. One laboratory experiment was designed to test microtextural implications in grains subjected to variable velocities, sediment concentration and time. The surface microscopic signature in quartz grains of high-energy events further contributes to the development of more efficient sedimentological criteria to identify deposits associated with tsunami and storm events.

Costa, Pedro J. M.; Andrade, C.; Dawson, A. G.; Mahaney, W. C.; Freitas, M. C.; Paris, R.; Taborda, R.

2012-11-01

57

Identification of secondary minerals crystallized by low and high temperature alteration in the Northern Kyushu-Palau Ridge volcanic rocks  

NASA Astrophysics Data System (ADS)

Seafloor rocks were affected by hydrothermal alteration and low temperature seawater weathering display various elemental behaviors, necessitating detailed investigations to evaluate primary bulk rock compositions without the effect of elemental behaviors during alteration. Seafloor alteration entails primary minerals being changed into hydrous minerals. Bulk chemical compositions of seafloor igneous rocks are changed by high- temperature hydrothermal alteration and low-temperature seafloor weathering. In this study, I report the secondary mineral identifications by XRD analyses in the rocks from the northern Kyushu-Palau Ridge, and consider to condition of alteration processes. Volcanic rocks dredged from the Northern Kyushu Palau Ridge during cruise by Tansei-maru, ORI, University of Tokyo show petrological and geochemical characteristics of low and high temperature alterations. These rocks are classified into bulk water content, that is, low H2O- and LOI samples at the Miyazaki Seamount, high H2O- samples at the Nichinan Seamount, and high LOI samples at the Komahashi-Daini Seamount. The Nichinan Seamount samples show flesh phenocrysts, low altered groundmass minerals, and high degree alteration of groundmass glass, assumed to replace into clay minerals. These altered phenocrysts are identified by XRD to be serpentine, saponite, and talc. And these altered groundmasses are identified by XRD to be saponite with primary plagioclase and clinopyroxene. These results are assumed to replacement of glass into clay minerals under low temperature seafloor weathering. Nichinan Seamount rocks show high alkali-elements contents. The remarkable movement of bulk composition is not occur under the low temperature seafloor weathering except for K and Rb, and these enrichments reflect secondary deposition of celadonite, K-rich smectite (e.g. Nakamura, 2001). Saponite is typical identified, but celadonite is not identified in the Nichinan Seamount rocks. Therefore, the characteristics of bulk composition of the Nichinan Seamount rocks are assumed similarity to primary signature. On the other hand, the Komahashi-Daini Seamount samples show completely re-crystallization, and igneous textures are observed to pseudomorph. These are identified by XRD to be quartz, clinochlore (one of chlorite), and albite. Secondary mineral assemblage is homogeneous in these rocks. The temperature of replacement by chlorite accompanied by enrichment in MgO is estimated to be more than 150°C on the basis of experimental studies (e.g. Mottle 1983). And interpreted two types of albitization, low temperature (< 50°C) and high temperature (> 100°C), are identified on the basis of study of ODP Leg 123 Site 765 igneous rocks (Gillis et al. 1992). Therefore, it is considered that volcanic rocks from the Komahashi-Daini Seamount were under effect of hydrothermal alteration more than 150°C. Many elements show significant movement under high temperature hydrothermal alteration (e.g. Laverne et al. 1996). That is, re-crystallization of chlorite under high temperature hydrothermal alteration accompanied addition of magnesium from seawater and remarkable bulk MgO enrichment (e.g. Nakamura, 2001). Therefore, it is considered that the Komahashi-Daini Seamount rocks show significant MgO-enrichment because of secondary mineralization of chlorite, and assumed to significant movement of other elements. These observations suggest that geochemical investigation of highly altered rocks must be made with caution.

Haraguchi, S.

2008-12-01

58

Bone growth enhancement in vivo on press-fit titanium alloy implants with acid etched microtexture  

PubMed Central

Early bone ongrowth secures long-term fixation of primary implants inserted without cement. Implant surfaces roughened with a texture on the micrometer scale are known to be osseoconductive. The aim of this study was to evaluate the bone formation at the surface of acid etched implants modified on the micro-scale. We compared implants with a nonparticulate texture made by chemical milling (hydrofluoric acid, nitric acid) (control) with implants that had a dual acid etched (hydrofluoric acid, hydrochloric acid) microtexture surface superimposed on the primary chemically milled texture. We used an experimental joint replacement model with cylindrical titanium implants (Ti-6Al-4V) inserted paired and press-fit in cancellous tibia metaphyseal bone of eight canines for 4 weeks and evaluated by histomorphometric quantification. A significant twofold median increase was seen for bone ongrowth on the acid etched surface [median, 36.1% (interquartile range, 24.3–44.6%)] compared to the control [18.4% (15.6–20.4%)]. The percentage of fibrous tissue at the implant surface and adjacent bone was significantly less for dual acid textured implants compared with control implants. These results show that secondary roughening of titanium alloy implant surface by dual acid etching increases bone formation at the implant bone interface.

Daugaard, Henrik; Elmengaard, Brian; Bechtold, Joan E.; Soballe, Kjeld

2013-01-01

59

The role of intragranular microtextures and microstructures in chemical and mechanical weathering: direct comparisons of experimentally and naturally weathered alkali feldspars  

NASA Astrophysics Data System (ADS)

Electron microscopic observations of alkali feldspars from soils show that intragranular microtextures, such as exsolution lamellae, and microstructures, primarily dislocations, are both highly significant determinants of the weathering behaviour of these minerals. In particular, strained structure around intersecting edge dislocations in the plane of exsolution lamellae, ˜( overline601), dissolves at a rate which is orders of magnitude greater than unstrained feldspar, producing a mesh of intersecting etch tubes extending >5 × 10 -3 cm into the crystal. As a result, dissolution at dislocations is the major source of solutes during initial stages of chemical weathering in the field. With progressive chemical weathering, the most highly reactive feldspar is consumed by growth and coalescence of etch tubes, but outer parts of the grain are physically weakened, leading to mechanical flaking that increases available surface area and exposes further reactive sites. In contrast, previous dissolution experiments, and microscopy of reacted surfaces, have shown little or no correlation between dissolution rate and dislocation density and few visible signs of dissolution at particularly reactive sites. To resolve the apparent discrepancy between field and laboratory behaviour we have carried out flow-through dissolution experiments using pH 2 HCl at 25°C on three alkali feldspars with carefully characterized intragranular microtextures and microstructures. These alkali feldspars were: (1) Eifel sanidine, an alkali feldspar that has no microtextures at the TEM scale and a low dislocation density (<10 6 cm -2), (2) unweathered alkali feldspars from the Shep Granite, which have a mainly coarse exsolution microtextures and higher dislocation density (>2-3 × 10 8 cm -2), and (3) naturally weathered alkali feldspars, also from the Shap Granite, which have the same microtextures as unweathered Shap Granite alkali feldspars but, because they have been weathered, have a lower density of dissolution reactive dislocations exposed on grain surfaces (<2-3 × 10 8 cm -2). Results from the experiments are ambiguous. If the rate data are normalised to the powder's initial BET surface area, dissolution rates increase with dislocation density. Normalisation to the powder's BET surface area as it is inferred to have changed during the experiments, yields no correlation with dislocation density. SEM and AFM images of reacted grain surfaces show that dislocation outcrops and albite exsolution lamellae have both etched more rapidly than tweed orthoclase, but dissolution at these sites makes a quantitatively insignificant contribution to the overall rate of laboratory dissolution of the feldspar powders. Major differences in the importance of dislocations to rates of early chemical weathering in field and laboratory contexts probably result from corresponding contrasts in the saturation state of ambient solutions. Observations of naturally weathered alkali feldspars show that microtextures and microstructures have the greatest impact on mineral weathering rates during advanced stages of dissolution when grain surfaces start to disintegrate. Hundreds of years of dissolution under the laboratory conditions used here would be required to reach this stage.

Lee, Martin R.; Hodson, Mark E.; Parsons, Ian

1998-08-01

60

MDD Analysis of Microtexturally Characterized K-Feldspar Fragments  

NASA Astrophysics Data System (ADS)

Multiple diffusion domain (MDD) analysis of K-feldspar 40Ar/39Ar age spectra is a powerful thermochronological tool dating back 25 years, but continued validation of the basic assumptions of the model can be afforded by microanalysis of K-feldspar crystal fragments. MDD theory assumes that diffusion of Ar in K-feldspars is controlled by domains of varying size bounded by infinitely fast diffusion pathways. However, the physical character of these domain boundaries is not fully understood and this issue remains a point of criticism of the MDD model. We have evaluated the relationship between texture, age, and thermal history via step heating and modeling of texturally characterized K-feldspar crystal fragments (250-500 ?m). K-feldspar phenocrysts from the Shap granite, chosen for their well-studied and relatively simple microtextures, contain large areas of homogenous regular strain-controlled film perthite with periodicities on the order of ~1 ?m and abundant misfit dislocations, as well as areas of much coarser, irregular, slightly turbid, patch and vein perthite. Total gas ages (TGA) for all Shap fragments, regardless of texture, show less than 2% variation, but the shape of the age spectra varies with microtexture. Film perthites produce flat spectra whereas patch/vein perthite spectra have initial steps 5 - 25% older than the age of the emplacement with younger plateau or gently rising steps afterward. Patch/vein perthites have substantial microporosity and their spectral shapes may be a consequence of trapped 40Ar* that has diffused into micropores or other defects that have no continuity with the crystal boundaries. Correlations between spectral shape and heating schedule suggest that initial old ages are produced by the early release of trapped 40Ar* separated from the K parent rather than degassing of excess 40Ar*. The MH-42 K-feldspar from the Chain of Ponds Pluton has two primary microtextures: a coarse patch/vein perthite with lamellae 1-20 ?m in width and a sparse patch perthite with fine (<5 ?m) or absent lamellae. Most fragments produce age spectra, TGA, and thermal histories duplicating the bulk sample. However, several fragments deviate from the bulk sample in age and do not produce a thermal history compatible with any segment of the bulk sample thermal history. Arrhenius parameters are essentially constant for all fragments and thus do not explain large variations in the apparent ages of some fragments (i.e., TGA from ~220 to 318 Ma). These incompatible ages and thermal histories may be a result of late stage metasomatic growth or recrystallization. This work highlights the benefits of greater sample characterization before destructive step heating and grants new understanding of Ar behavior within plutonic K-feldspars. Newly installed high sensitivity multicollector mass spectrometers (ARGUS VI) will afford higher resolution age spectrum and in situ analysis on even smaller fragments. It is expected that these instruments will provide the precision necessary to enhance our understanding of MDD analysis as we move forward during the next 25 years of thermochronology.

Short, C. H.; Heizler, M. T.; Parsons, I.; Heizler, L.

2011-12-01

61

Secondary mineral growth in fractures in the Miravalles geothermal system, Costa Rica  

SciTech Connect

A mineralogical, fluid-chemical, and theoretical study of hydrothermal alteration in veins from drillcore from the Miravalles geothermal field, Costa Rica has revealed a complex history of mineral-fluid reaction which may be used to characterize changes in temperature and fluid composition with time. Mineralogical and mineral-chemical data are consistent with hydrothermal alteration in the temperature range 200{sup 0}-270{sup 0}C, with deeper portions of the system having undergone temperatures in excess of 300{sup 0}C. Thermodynamic calculations suggest that the observed alteration assemblage is not equilibrium with current well fluids, unless estimates of reservoir pH are incorrect. Fe-Al zoning of prehnite and epidote in veins is consistent with rapid, isothermal fluctuations in fluid composition at current reservoir temperatures, and may be due to changes in volatile content of the fluid due to tectonic activity.

Rochelle, C.A. (Leeds Univ. (UK). Dept. of Earth Sciences); Milodowski, A.E.; Savage, D. (British Geological Survey, Keyworth (UK). Fluid Processes Research Group); Corella, M. (Instituto Costarricense de Electricidad, San Jose (Costa Rica))

1989-01-01

62

The Effects of Secondary Mineral Precipitates on 90Sr Mobility at the Hanford Site, USA  

SciTech Connect

The effects of secondary precipitates on 90Sr transport at the Hanford Site were investigated using quartz column experiments with simulated caustic tank waste leachates (STWL). Significantly enhanced retardation of Sr transport was observed in the column contacted with STWL due to Sr sorption and co-precipitation with neo-formed nitratecancrinite. However, the column results also suggest that neo-formed secondary precipitates could behave like native mobile colloids that can enhance Sr transport. Initially immobilized Sr within secondary precipitates could remobilize given a change in the porewater background conditions. The mobility of the neo-formed Sr-bearing precipitates increased with increased solution flow rate. In the field, porewater contents and flow rates can be changed by snowmelt (or storm water) events or artificial infiltration. The increased porewater flow rate caused by these events could affect the mobility of 90Sr-containing secondary precipitates, which can be a potential source for facilitated Sr transport in Hanford Site subsurface environments.

Um, Wooyong; Wang, Guohui; Serne, R. Jeffrey

2013-06-03

63

Secondary Recovery: Change of the Viscosity and Compressibility of Mineral Oils by Dissolved Gas.  

National Technical Information Service (NTIS)

Secondary and tertiary oil recovery methods for an enhancement of the production rate are mostly based on a reduction of the mobility ratio water/oil. This can be achieved e.g. by lowering of the oil viscosity by heat or dissolved gases. To investigate th...

E. Kuss H. Killesreiter

1981-01-01

64

Characterization of Secondary Mineral Grain Coatings and their Role as Diffusion-controlled Sinks and Sources for Metal Contaminants  

NASA Astrophysics Data System (ADS)

Many important geochemical reactions occur at the mineral-water interface, including sorption and desorption reactions of contaminants. Fundamental knowledge of the kinetics of these processes is based primarily on experimental observations of reactions at faces of single crystals or macroscopic data from pure mineral powder suspensions. Sorption reactions at crystal faces are generally very fast, on the order of microseconds or less, with reaction times often limited only by film diffusion at the mineral-water interface. In well-stirred suspensions of aquifer sediments, however, sorptive equilibrium can take many hours or days to achieve steady-state concentrations. We have examined the potential reasons for sorption rate limitation using uranium(VI) sorption by sediments from a sandy aquifer in Savannah River, South Carolina (USA). U(VI) sorption by sand-sized grains from the aquifer is dominated by reaction with secondary mineral coatings on quartz and feldspar grains. The coatings studied were on the order of 15 microns in thickness (i.e., from quartz grain to aqueous solution) and composed primarily of clay minerals and hematite of varying particle size. Microfocused-XRF imaging of elemental concentrations (e.g., U, Fe) of polished cross-sections of the grain/coating contact showed strong spatial correlations of U and Fe within the coatings, regardless of the length of reaction time (30 minutes to 4 weeks). The spatial resolution of the ?-XRF technique is of the order of 2 microns in horizontal directions, but the uncertainty of the observed spatial gradients is high due to grain curvature away from the polished surface and fluorescence contributed from the entire 30 micron thickness of a typical grain/epoxy thin section. TEM characterization of focused-ion-beam (FIB), vertically-extracted samples of the grain-coating contact shows that complex pore networks exist within the coatings of variable dimensions and unknown connectivity. Using scanning TEM (STEM) tomography, it can be seen that there are large numbers of pore throat sizes less than 10 nm within the coatings. We hypothesize that diffusion through these pores, which likely have electrically charged surfaces, controls the observed macroscopic rates of U(VI) sorption in batch experiments with sand grains. Evidence to support this hypothesis was observed by studying U and Fe fluorescence spatial variation within FIB samples (1 micron thick) at 200 nm spatial resolution. With this greater spatial resolution, it is possible to see U concentration variations within the coatings that are dependent on the time of sorption reaction, and illustrates how the coating environment constitutes a diffusion constraint to achieve adsorptive equilibrium between an aqueous phase and the mineral surfaces. Including this diffusion constraint within conceptual models for reactive contaminant transport may be significant at the field scale, because secondary mineral coatings are potentially both sinks and sources of contaminants depending on the history of a contaminated site. This is important in resolving long-term transport predictions at DOE sites, such as Hanford and Savannah River, where equilibrium versus kinetic reactive transport models are being evaluated.

Davis, J. A.; Guo, H.; Lai, B.; Kemner, K. M.; Ercius, P.; Fox, P. M.; Singer, D. M.; Minor, A.; Waychunas, G.

2012-12-01

65

Exchangeable and secondary mineral reactive pools of aluminium in coastal lowland acid sulfate soils.  

PubMed

The use of coastal floodplain sulfidic sediments for agricultural activities has resulted in the environmental degradation of many areas worldwide. The generation of acidity and transport of aluminium (Al) and other metals to adjacent aquatic systems are the main causes of adverse effects. Here, a five-step sequential extraction procedure (SEP) was applied to 30 coastal lowland acid sulfate soils (CLASS) from north-eastern New South Wales, Australia. This enabled quantification of the proportion of aluminium present in 'water-soluble', 'exchangeable', 'organically-complexed', 'reducible iron(III) (oxyhydr)oxide/hydroxysulfate-incorporated' and 'amorphous Al mineral' fractions. The first three extractions represented an average of 5% of 'aqua regia' extractable Al and their cumulative concentrations were extremely high, reaching up to 4000mg·kg(-1). Comparison of Al concentrations in the final two extractions indicated that 'amorphous Al minerals' are quantitatively a much more important sink for the removal of aqueous Al derived from the acidic weathering of these soils than reducible Fe(III) minerals. Correlations were observed between soil pH, dissolved and total organic carbon (DOC and TOC) and Al concentrations in organic carbon-rich CLASS soil horizons. These results suggest that complexation of Al by dissolved organic matter significantly increases soluble Al concentrations at pH values >5.0. As such, present land management practices would benefit with redefinition of an 'optimal' soil from pH ?5.5 to ~4.8 for the preservation of aquatic environments adjacent to organic-rich CLASS where Al is the sole or principle inorganic contaminant of concern. Furthermore, it was observed that currently-accepted standard procedures (i.e. 1M KCl extraction) to measure exchangeable Al concentrations in these types of soils severely underestimate exchangeable Al and a more accurate representation may be obtained through the use of 0.2M CuCl2. PMID:24727041

Yvanes-Giuliani, Yliane A M; Waite, T David; Collins, Richard N

2014-07-01

66

Mechanically robust superamphiphobic aluminum surface with nanopore-embedded microtexture.  

PubMed

A simple fabrication technique was developed for preparing a mechanically robust superamphiphobic surface on an aluminum (Al) plate. Dual geometric architectures with micro- and nanoscale structures were formed on the surface of the Al plate by a combination of simple chemical etching and anodization. This proposed methodology involves (1) fabrication of irregular microscale plateaus on the surface of the Al plate, (2) formation of nanopores, and (3) fluorination. Wettability measurements indicated that the fabricated Al surface became super-repellent toward a broad range of liquids with surface tension in the range 27.5-72 mN/m. By varying the anodization time, we measured and compared the effects of morphological change on the wettability. The adhesion property and mechanical durability of the fabricated superamphiphobic Al surface were evaluated by the Scotch tape and hardness tests, respectively. The results showed that the fabricated Al surface retained mechanical robustness because the down-directed surface made by nanopores on the microtextured surface was durable enough even after high force was applied. Almost no damage of the film was observed, and the surface still exhibited superamphiphobicity after the tests. The fabricated superamphiphobic surface also remained stable after long-term storage. The simple and time-saving fabrication technique can be extended to any large-area three-dimensional surface, making it potentially suitable for large-scale industrial fabrications of mechanically robust superamphiphobic surfaces. PMID:23980795

Barthwal, Sumit; Kim, Young Su; Lim, Si-Hyung

2013-09-24

67

Droplet motion on designed microtextured superhydrophobic surfaces with tunable wettability.  

PubMed

Superhydrophobic surfaces have shown promising applications in microfluidic systems as a result of their water-repellent and low-friction properties over the past decade. Recently, designed microstructures have been experimentally applied to construct wettability gradients and direct the droplet motion. However, thermodynamic mechanisms responsible for the droplet motion on such regular rough surfaces have not been well understood such that at present specific guidelines for the design of tunable superhydrophobic surfaces are not available. In this study, we propose a simple but robust thermodynamic methodology to gain thorough insight into the physical nature for the controllable motion of droplets. On the basis of the thermodynamic calculations of free energy (FE) and the free-energy barrier (FEB), the effects of surface geometry of a pillar microtexture are systematically investigated. It is found that decreasing the pillar width and spacing simultaneously is required to lower the advancing and receding FEBs to effectively direct droplets on the roughness gradient surface. Furthermore, the external energy plays a role in the actuation of spontaneous droplet motion with the cooperation of the roughness gradient. In addition, it is suggested that the so-called "virtual wall" used to confine the liquid flow along the undesired directions could be achieved by constructing highly advancing FEB areas around the microchannels, which is promising for the design of microfluidic systems. PMID:18788770

Fang, Guoping; Li, Wen; Wang, Xiufeng; Qiao, Guanjun

2008-10-21

68

Secondary mineralization pathways induced by dissimilatory iron reduction of ferrihydrite under advective flow  

Microsoft Academic Search

Iron (hydr)oxides not only serve as potent sorbents and repositories for nutrients and contaminants but also provide a terminal electron acceptor for microbial respiration. The microbial reduction of Fe (hydr)oxides and the subsequent secondary solid-phase transformations will, therefore, have a profound influence on the biogeochemical cycling of Fe as well as associated metals. Here we elucidate the pathways and mechanisms

Colleen M. Hansel; Shawn G. Benner; Jim Neiss; Alice Dohnalkova; Ravi K. Kukkadapu; Scott Fendorf

2003-01-01

69

Effect of mineral dust on secondary organic aerosol yield and aerosol size in ?-pinene/NOx photo-oxidation  

NASA Astrophysics Data System (ADS)

Although it is a significant contributor to atmospheric particles, the role of mineral dust in secondary organic aerosol (SOA) formation has not been fully recognized. In this study, alumina was chosen as the surrogate to investigate the effect of mineral dust on ?-pinene/NOx photo-oxidation in a 2 m3 smog chamber at 30 °C and 50% relative humidity (RH). Results showed that alumina seeds could influence both the SOA yield and the aerosol size in the photo-oxidation process. Compared to the seed-free system, the presence of alumina seeds resulted in a slight reduction of SOA yield, and also influenced the final concentration of O3 in the chamber. As an important oxidant of ?-pinene, the decrease in O3 concentration could reduce the formation of semi-volatile compounds (SVOCs) and consequently inhibited SOA formation. In addition, the size of aerosol was closely related with the mass loading of alumina seeds. At low alumina concentration, SVOCs condensed onto the pre-existing seed surface and led to aerosol size growth. When alumina concentration exceeded about 5 ?g m?3, SVOC species that condensed to each seed particle were dispersed by alumina seeds, resulting in the decrease in aerosol size.

Liu, Chang; Chu, Biwu; Liu, Yongchun; Ma, Qingxin; Ma, Jinzhu; He, Hong; Li, Junhua; Hao, Jiming

2013-10-01

70

Organic carbon and reducing conditions lead to cadmium immobilization by secondary Fe mineral formation in a pH-neutral soil.  

PubMed

Cadmium (Cd) is of environmental relevance as it enters soils via Cd-containing phosphate fertilizers and endangers human health when taken up by crops. Cd is known to associate with Fe(III) (oxyhydr)oxides in pH-neutral to slightly acidic soils, though it is not well understood how the interrelation of Fe and Cd changes under Fe(III)-reducing conditions. Therefore, we investigated how the mobility of Cd changes when a Cd-bearing soil is faced with organic carbon input and reducing conditions. Using fatty acid profiles and quantitative PCR, we found that both fermenting and Fe(III)-reducing bacteria were stimulated by organic carbon-rich conditions, leading to significant Fe(III) reduction. The reduction of Fe(III) minerals was accompanied by increasing soil pH, increasing dissolved inorganic carbon, and decreasing Cd mobility. SEM-EDX mapping of soil particles showed that a minor fraction of Cd was transferred to Ca- and S-bearing minerals, probably carbonates and sulfides. Most of the Cd, however, correlated with a secondary iron mineral phase that was formed during microbial Fe(III) mineral reduction and contained mostly Fe, suggesting an iron oxide mineral such as magnetite (Fe3O4). Our data thus provide evidence that secondary Fe(II) and Fe(II)/Fe(III) mixed minerals could be a sink for Cd in soils under reducing conditions, thus decreasing the mobility of Cd in the soil. PMID:24191747

Muehe, E Marie; Adaktylou, Irini J; Obst, Martin; Zeitvogel, Fabian; Behrens, Sebastian; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas

2013-12-01

71

Systematic variations in sinter mineralogy, microtexture and diagenesis in modern siliceous hot springs: Clues for interpreting depositional conditions in ancient deposits  

NASA Astrophysics Data System (ADS)

The deposits of siliceous hydrothermal springs are known to capture and preserve a wide range of microbial fossil information. The recent discovery of hydrothermal silica at Home Plate, Columbia Hills, Mars has once again raised interest in the potential importance of ancient spring sinters as targets for future astrobiological mission to Mars. To create additional context information to support future in situ missions to Mars, we have documented systematic changes in the mineralogy and microtexture of modern siliceous hot spring deposits, observed along gradients in temperature, pH and flow velocity. Specific objectives are to: 1) identify chemical and physical factors that promote early diagenetic transformations of amorphous silica (opal-A), to progressively more ordered and crystalline phases (cristobalite, tridymite and quartz); 2) determine the composition and abundance of minor mineral phases, especially clays, in relationship to pH, temperature and paragenesis; and 3) to assess the usefulness of sinter mineralogy and microtexture in reconstructing the paleoenvironmental records preserved in ancient deposits. Study sites for acidic (pH 2-5) sinters included Nymph Creek, located in the Norris Geyser Basin of Yellowstone National Park (YNP). Active alkaline (pH 7-10) springs included Rabbit Creek, Steep Cone and Mound Spring located in the Lower Geyser Basin, YNP. Field measurements in active springs included pH, temperature and flow velocity, along with general microfacies assignments. To better constrain types and rates of silica diagenesis, the study also sampled older (Holocene-Pleistocene-aged) deposits. Laboratory analyses included X-ray powder diffraction (XRPD), thermal infrared spectroscopy (TIR) and thin section petrography for characterizing sinter microtextures and for placing mineral phases (identified by XRPD and TIR) into a time-ordered diagenetic framework. In analyzing the phyllosilicates present in sinters, we applied clay separation and glycolization methods, with XRPD. Results indicate that all of the acidic sinters we studied showed more extensive early diagenetic ordering of silica phases (opal-A to cristobalite and quartz) than the comparable microfacies of alkaline-neutral sinters. Clay analyses showed no evidence for smectitic (expansive) clays, but kaolin family clays (dickite, kaolinite and halloysite) were present in both acidic and alkaline sinters. The microfacies distribution observed for clays suggests: 1) dickite being more abundant in higher temperature (near-vent) microfacies, 2) kaolinite dominating mid-temperature outflow channels, slope and upper distal apron microfacies, and 3) halloysite being restricted to lower distal apron-marsh microfacies transitions. Future work will expand clay analyses to apply near-IR spectroscopy to a broader range of samples to assess the consistency with patterns suggested from XRPD.

Mills, V. W.; Farmer, J. D.; Ruff, S. W.; Nunez, J.; Jahnke, L. L.

2011-12-01

72

Reduction of barnacle recruitment on micro?textured surfaces: Analysis of effective topographic characteristics and evaluation of skin friction  

Microsoft Academic Search

This study investigates five designed micro?textured surfaces and their effects on barnacle fouling and hydrodynamic drag. Three of the micro?textures were developed in the present study and evaluated together with two commercial riblet films. All micro?structures were arranged as longitudinal grooves with different profile depths, widths and angles of inclination. In field tests the recruitment of the barnacle Balanus improvisus

K. M. Berntsson; H. Andreasson; P. R. Jonsson; L. Larsson; K. Ring; S. Petronis; P. Gatenholm

2000-01-01

73

Effect of doxercalciferol (1alpha-hydroxyvitamin D2) on PTH, bone turnover and bone mineral density in a hemodialysis patient with persistent secondary hyperparathyroidism post parathyroidectomy.  

PubMed

The efficacy and safety of the vitamin D analog, doxercalciferol (1alpha-hydroxyvitamin D2, 1alphaD2) in the treatment of secondary hyperparathyroidism in hemodialysis patients has been previously reported. We report these effect of 16-week 1alphaD2 treatment on mineral metabolism and bone mineral density (BMD) in a hemodialysis patient with persistent secondary hyperparathyroidism post parathyroidectomy, resistant to previous calcitriol treatment. Levels of iPTH, bone-specific alkaline phosphatase and serum type I collagen C telopeptide were above normal at baseline and were substantially decreased with 1alphaD2 treatment (-92%, -63% and -53%, respectively). BMD increased in all areas: total skeleton (+6.5%), lumbar spine (+6.9%) and total femur (+4.3%). The patient showed no hypercalcemia, and phosphorus levels remained between 3.3 and 6.2 mg/dl. PMID:12834181

Parisi, M S; Oliveri, B; Somoza, J; Mautalen, C

2003-06-01

74

Micro-textured conductive polymer/silicon heterojunction photovoltaic devices with high efficiency  

NASA Astrophysics Data System (ADS)

In this work, hybrid heterojunction solar cells are demonstrated based on a conjugate polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) directly spun-cast on micro-textured n-type crystalline silicon wafers. The fabrication conditions suggest that the organic coverage on the micro-textured surface is excellent and key to achieve high efficiency, leading to an average power conversion efficiency of 9.84%. A one-dimensional drift-diffusion model is then developed based on fitting the device characteristics with experimentally determined PEDOT:PSS parameters and projects an ultimate efficiency above 20% for organic/inorganic hybrid photovoltaics. The simulation results reveal the impacts of defect densities, back surface recombination, doping concentration, and band alignment.

Chen, Ting-Gang; Huang, Bo-Yu; Chen, En-Chen; Yu, Peichen; Meng, Hsin-Fei

2012-07-01

75

Microtexture in the friction-stir weld of an aluminum alloy  

Microsoft Academic Search

In order to characterize plastic flow during friction-stir welding, the microtextures in a friction-stir weld of the precipitation-hardened\\u000a aluminum alloy 6063 have been analyzed by orientation imaging microscopy (OIM). The base-material plate has a Goss orientation.\\u000a The weld center region, except for the upper surface, takes a typical shear texture component with two types of orientations.\\u000a The orientations have a

Yutaka S. Sato; Hiroyuki Kokawa; Keiske Ikeda; Masatoshi Enomoto; Takenori Hashimoto; Shigetoshi Jogan

2001-01-01

76

Teasing apart the contributions of hard dietary items on 3D dental microtextures in primates.  

PubMed

3D dental microtexture analysis is a powerful tool for reconstructing the diets of extinct primates. This method is based on the comparison of fossils with extant species of known diet. The diets of primates are highly diversified and include fruits, seeds, grass, tree leaves, bark, roots, tubers, and animal resources. Fruits remain the main component in the diets of most primates. We tested whether the proportion of fruit consumed is correlated with dental microtexture. Two methods of microtexture analysis, the scale-sensitive fractal analysis (SSFA) and the Dental Areal Surface Texture Analysis (DASTA; after ISO/FDIS 25178-2), were applied to specimens of eight primate species (Alouatta seniculus, Gorilla gorilla, Lophocebus albigena, Macaca fascicularis, Pan troglodytes, Papio cynocephalus, Pongo abelii, Theropithecus gelada). These species largely differ in the mean annual proportion of fruit (from 0 to 90%) in their diet, as well as in their consumption of other hard items (seeds, bark, and insect cuticles) and of abrasive plants. We find the complexity and heterogeneity of textures (SSFA) to correlate with the proportion of fruits consumed. Textural fill volume (SSFA) indicates the proportion of both fruits and other hard items processed. Furthermore, anisotropy (SSFA) relates to the consumption of abrasive plants like grass and other monocots. ISO parameters valley height, root mean square height, material volume, density of peaks, and closed hill and dale areas (DASTA) describe the functional interaction between food items and enamel facets during mastication. The shallow, plastic deformation of enamel surfaces induced by small hard particles, such as phytoliths or dust, results in flat microtexture relief, whereas the brittle, deep fracture caused by large hard items such as hard seeds creates larger relief. PMID:22705031

Calandra, Ivan; Schulz, Ellen; Pinnow, Mona; Krohn, Susanne; Kaiser, Thomas M

2012-07-01

77

Time–temperature evolution of microtextures and contained fluids in a plutonic alkali feldspar during heating  

Microsoft Academic Search

Microtextural changes brought about by heating alkali feldspar crystals from the Shap granite, northern England, at atmospheric\\u000a pressure, have been studied using transmission and scanning electron microscopy. A typical unheated phenocryst from Shap is\\u000a composed of about 70 vol% of tweed orthoclase with strain-controlled coherent or semicoherent micro- and crypto-perthitic\\u000a albite lamellae, with maximum lamellar thicknesses <1 ?m. Semicoherent lamellae are encircled

Ian ParsonsJohn; John D. Fitz Gerald; James K. W. Lee; Tim Ivanic; Ute Golla-Schindler

2010-01-01

78

EBSD study on YBCO textured bulk samples: correlation between crystal growth and 'microtexture'  

Microsoft Academic Search

This work describes an electron backscattered diffraction (EBSD) study of the perovskite-derived structures YBa2Cu3O7-delta. After having pointed out the difficulties of EBSD analyses in resolving the orientations of these pseudo-cubic structures, various YBaCuO bulk samples are analysed and the correlation between the microstructure, crystal growth and global texture, determined by neutron diffraction, is carried out. Homogeneous 'microtexture' with small subdomain

D. Grossin; C. Henrist; J.-Ph Mathieu; S. Meslin; C. Harnois; J.-G. Noudem; R. Cloots; D. Chateigner

2006-01-01

79

Use of secondary mineralizing raw materials in cement production. A case study of a wolframite–stibnite ore  

Microsoft Academic Search

It has been found that certain foreign elements, despite their low concentration in cement raw mix, improve the reactivity of the cement raw mix. The aim of this research is to investigate the possibility of introducing small amounts of minerals, containing these elements, into the cement raw mix. A stibnite–wolframite mineral was selected in order to introduce W, Sb and

G. Kakali; S. Tsivilis; K. Kolovos; N. Voglis; J. Aivaliotis; T. Perraki; E. Passialakou; M. Stamatakis

2005-01-01

80

Heavy minerals in surficial sediments from lower Cook Inlet, Alaska  

USGS Publications Warehouse

Amphiboles, orthopyroxenes, and clinopyroxenes dominate the heavy mineral suite of surficial sediments in lower Cook Inlet, Alaska. Sources for these sediments include the igneous arc terrane of the northeast Alaska Range, reworked intrabasinal sediments, and local drainages in lower Cook Inlet. The distribution of these deposits is a reflection of both the tidal currents and the prevailing southerly net movement from the head of Cook Inlet. The heavy mineral studies concur with similar findings from gravel analyses, clay mineral investigations, and quartz microtexture observations. ?? 1984 Springer-Verlag New York Inc.

Wong, F. L.

1984-01-01

81

Framework for estimating potential wastes and secondary resources accumulated within an economy – A case study of construction minerals in Japan  

Microsoft Academic Search

Material stocks in economic society are considered to represent a reserve for wastes and secondary resources. From the viewpoints of proper disposal and reutilization of stocked materials, accurate estimation of the amount of materials that will emerge as wastes or secondary resources in the future is important. We defined materials that have a high probability of emerging as wastes or

Seiji Hashimoto; Hiroki Tanikawa; Yuichi Moriguchi

2009-01-01

82

EMSP Project 70070: Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks - Final Report  

SciTech Connect

Since the late 1950s, leaks from 67 single-shell tanks at the Hanford Site have released about 1 million curies to the underlying sediments. The radioactive material was contained in water-based solutions generally characterized as having high pH values (basic solutions), high nitrate and nitrite concentrations, and high aluminum concentrations. The solutions were also hot, in some cases at or near boiling, as well as complex and highly variable in composition reflecting solutions obtained from multiple methods of reprocessing spent nuclear fuel. In order to understand the observed and probable distribution of radionuclides in the ground at Hanford, major reactions that likely occurred between the leaked fluids and the sediment minerals were investigated in laboratory experiments simulating environmental conditions. Reactions involving the dissolution of quartz and biotite and the simultaneous formation of new minerals were quantified at controlled pH values and temperature. Result s show that the dissolution of quartz and formation of new zeolite-like minerals could have altered the flow path of ground water and contaminant plumes and provided an uptake mechanism for positively-charged soluble radionuclides, such as cesium. The dissolution of biotite, a layered-iron-aluminum-silicate mineral, provided iron in a reduced form that could have reacted with negatively-charged soluble chromium, a toxic component of the wastes, to cause its reduction and precipitation as a new reduced-chromium mineral. The quantity of iron released in the experiments is sufficient to explain observations of reductions in dissolved chromium concentration in a plume beneath one Hanford tank. Fundamental data obtained in the project are the rates of the reactions at variable temperatures and pHs. Fundamental data were also obtained on aspects of the surface reactivity of clay or layered-silicate minerals, a small proportion of the total mass of the sediment minerals, but a large proportion of the number of sites where reactions can occur. Results were also finalized on a component of a previous project related to the Hanford waste tanks that had the goal of measuring the incorporation of rhenium, an analogue of radioactive technetium, in iron and aluminum-oxides minerals as they aged in tank sludges at higher temperatures. Small amounts of rhenium were occluded in the iron-rich solids and the amount increased with aging time. Results from the quartz and biotite experiments are in a form that can be used in models of fluid flow in the Hanford subsurface. Results from the rhenium experiments can be used to understand aspects of closing certain of the Hanford tanks.

Kathryn L. Nagy

2004-04-22

83

Laser surface micro-texturing to enhance the frictional behavior of lubricated steel  

NASA Astrophysics Data System (ADS)

Surface micro-texturing has been widely theoretically and experimentally demonstrated to be beneficial to friction reduction in sliding contacts under lubricated regimes. Several microscopic mechanisms have been assessed to concur to this macroscopic effect. In particular, the micro-textures act as lubricant reservoirs, as well as traps for debris. Furthermore, they may produce a local reduction of the shear stress coupled with a stable hydrodynamic pressure between the lubricated sliding surfaces. All these mechanisms are strongly dependent both on the micro-texturing geometry and on the operating conditions. Among the various micro-machining techniques, laser ablation with ultrashort pulses is an emerging technology to fabricate surface textures, thanks to the intrinsic property of laser light to be tightly focused and the high flexibility and precision achievable. In addition, when using sub-ps pulses, the thermal damage on the workpiece is negligible and the laser surface textures (LST) are not affected by burrs, cracks or resolidified melted droplets, detrimental to the frictional properties. In this work several LST geometries have been fabricated by fs-laser ablation of steel surfaces, varying the diameter, depth and spacing of micro-dimples squared patterns. We compared their frictional performance with a reference nontextured sample, on a range of sliding velocities from the mixed lubrication to the hydrodynamic regime. The measured Stribeck curves data show that the depth and diameter of the microholes have a huge influence in determining the amount of friction reduction at the interface. Different theoretical interpretations to explain the experimental findings are also provided.

Ancona, Antonio; Carbone, Giuseppe; Scaraggi, Michele; Mezzapesa, Francesco P.; Sorgente, Donato; Lugarà, Pietro M.

2014-03-01

84

Secondary sulfate minerals associated with acid drainage in the eastern US: Recycling of metals and acidity in surficial environments  

USGS Publications Warehouse

Weathering of metal-sulfide minerals produces suites of variably soluble efflorescent sulfate salts at a number of localities in the eastern United States. The salts, which are present on mine wastes, tailings piles, and outcrops, include minerals that incorporate heavy metals in solid solution, primarily the highly soluble members of the melanterite, rozenite, epsomite, halotrichite, and copiapite groups. The minerals were identified by a combination of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron-microprobe. Base-metal salts are rare at these localities, and Cu, Zn, and Co are commonly sequestered as solid solutions within Fe- and Fe-Al sulfate minerals. Salt dissolution affects the surface-water chemistry at abandoned mines that exploited the massive sulfide deposits in the Vermont copper belt, the Mineral district of central Virginia, the Copper Basin (Ducktown) mining district of Tennessee, and where sulfide-bearing metamorphic rocks undisturbed by mining are exposed in Great Smoky Mountains National Park in North Carolina and Tennessee. Dissolution experiments on composite salt samples from three minesites and two outcrops of metamorphic rock showed that, in all cases, the pH of the leachates rapidly declined from 6.9 to 30 mg L-1), Fe (>47 mg L-1), sulfate (>1000 mg L-1), and base metals (>1000 mg L-1 for minesites, and 2 mg L-1 for other sites). Geochemical modeling of surface waters, mine-waste leachates, and salt leachates using PHREEQC software predicted saturation in the observed ochre minerals, but significant concentration by evaporation would be needed to reach saturation in most of the sulfate salts. Periodic surface-water monitoring at Vermont minesites indicated peak annual metal loads during spring runoff. At the Virginia site, where no winter-long snowpack develops, metal loads were highest during summer months when salts were dissolved periodically by rainstorms following sustained evaporation during dry spells. Despite the relatively humid climate of the eastern United States, where precipitation typically exceeds evaporation, salts form intermittently in open areas, persist in protected areas when temperature and relative humidity are appropriate, and contribute to metal loadings and acidity in surface waters upon dissolution, thereby causing short-term perturbations in water quality.

Hammarstrom, J. M.; Seal, II, R. R.; Meier, A. L.; Kornfeld, J. M.

2005-01-01

85

Mineral catalyzed organic synthesis in hydrothermal systems: An experimental study using time-of-flight secondary ion mass spectrometry  

NASA Astrophysics Data System (ADS)

Hydrothermal fluids enriched in hydrocarbons of apparent abiotic origin vent from Fe-Ni sulfide bearing chimney structures on the seafloor at slow spreading mid-ocean ridges. Here we show results from a hydrothermal experiment using carbon isotope labeling techniques and mineral analytical data that indicate that pentlandite ((Fe2Ni7)S8) enhances formation of C2 and C3 alkanes, while also contributing to the formation of other more complex hydrocarbons, such as alcohols and carboxylic acids. ToF-SIMS data reveal the existence of isotopically anomalous carbon on the pentlandite surface, and thus, for the first time, provide unambiguous evidence that mineral catalyzed surface reactions play a role in carbon reduction schemes under hydrothermal conditions. We hypothesize that hydroxymethylene (-CHOH) serves as intermediary facilitating formation of more complex organic compounds. The experimental results provide an explanation for organic synthesis in ultramafic-hosted hydrothermal systems on earth, and on other water-enriched planetary bodies as well.

Fu, Qi; Foustoukos, Dionysios I.; Seyfried, William E.

2008-04-01

86

Microstructure and Microtexture Evolution of Shear Localization in Dynamic Deformation with Different Strains in Annealed Copper  

NASA Astrophysics Data System (ADS)

Shear localizations with different strains in annealed copper were obtained by a modified split Hopkinson pressure bar. Microstructure and microtexture evolution of the shear localization regions were examined using optical microscopy, electron backscatter diffraction technique, and transmission electron microscopy. The results show that both the mechanical response and deformation behavior are correlated closely to the shear strains. The elongated dislocation cells, stretched subgrains, and the refinement of subgrains are observed within shear localizations during dynamic deformation. Ultrafine grains of 100 to 300 nm with high-angle-boundaries are produced within the shear band with the shear strain of 5.8. Microtexture characterization reveals that a stable orientation, in which <110> directions of the crystals tend to align with the shear direction, develops both in the deformation and recrystallization areas. The {111} planes of the crystals tend to parallel to the shear plane in the deformation area, whereas the aggregated extent of this orientation becomes weak in the recrystallization area. In addition, some grains exist with the {100} planes parallel to the shear plane in the deformation and recrystallization areas. The rotational dynamic recrystallization is a reasonable mechanism for the microstructure evolution. The effects of cooling stage on the growth of grains and the change of dislocation density are estimated as a complementarity to this mechanism.

Tang, Lin; Chen, Zhiyong; Zhan, Congkun; Yang, Xuyue; Liu, Chuming

2013-02-01

87

Nutritional secondary hyperparathyroidism in two cats: evaluation of bone mineral density with dual-energy X-ray absorptiometry and computed tomography.  

PubMed

Two three-month-old, intact female Abyssinian cats were presented with a history of lameness, constipation and ataxia. The cats had been fed a diet composed almost exclusively of meat. Both showed severe osteopenia and multiple pathological fractures on radiography. Following euthanasia of the more severely affected cat, postmortem examination revealed changes consistent with nutritional secondary hyperparathyroidism and fibrous osteodystrophy, such as cortical thinning, massive connective tissue invasion in the diaphysis of long bones, and hypertrophy of the chief cells in both parathyroid glands. After introducing a balanced commercial diet to the surviving cat, bone mineralisation improved from the baseline value, and at subsequent examinations at three, six and 22 weeks later, as indicated by bone mineral density measurements obtained by dual-energy X-ray absorptiometry and computed tomography. PMID:19997669

Dimopoulou, M; Kirpensteijn, J; Nielsen, D H; Buelund, L; Hansen, M S

2010-01-01

88

DOE FG02-03ER63557: Final Technical Report: Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks  

SciTech Connect

The purpose of the project was to investigate rates and mechanisms of reactions between primary sediment minerals and key components of waste tank solutions that leaked into the subsurface at the Hanford Site. Results were expected to enhance understanding of processes that cause (1) changes in porosity and permeability of the sediment and resultant changes in flow paths of the contaminant plumes, (2) formation of secondary precipitates that can take up contaminants in their structures, and (3) release of mineral components that can drive redox reactions affecting dissolved contaminant mobility. Measured rates can also be used directly in reactive transport models. Project tasks included (1) measurement of the dissolution rates of biotite mica from low to high pH and over a range of temperature relevant to the Hanford subsurface, (2) measurement of dissolution rates of quartz at high pH and in the presence of dissolved alumina, (3) measurement of the dissolution rates of plagioclase feldspar in high pH, high nitrate, high Al-bearing solutions characteristic of the BX tank farms, (4) incorporation of perrhenate in iron-oxide minerals as a function of pH, and (5) initiation of experiments to measure the formation of uranium(VI)-silicate phases under ambient conditions. Task 2 was started under a previous grant from the Environmental Management Science Program and Task 4 was partially supported by a grant to the PI from the Geosciences Program, Office of Basic Energy Sciences. Task 5 was continued under a subsequent grant from the Environmental Remediation Sciences Program, Office of Biological and Environmental Research.

Kathryn L. Nagy

2009-05-04

89

Microtexture and Nanoindentation Study of Delamination Cracking in Al-Cu-Li-X Alloys  

NASA Technical Reports Server (NTRS)

Commercial Al-Li alloys have strength and weight advantages over non-Li aluminum alloys. The fracture behavior of these alloys is unusual and has limited their use. The fracture mode, described as delamination, is intergranular, along the broad grain boundaries parallel to the rolling plane of the plate. Microtexture analyses have shown that delaminations occur along boundaries with greater than 30 misorientation. However, it was observed that relatively few of the high angle boundaries exhibited this behavior. Some grains of the retained deformation texture show high internal misorientation, which is a measure of stored strain energy. Delamination tends to occur between these grains and adjacent, recrystallized grains. Nanoindentation studies indicate a higher hardness for the high internal misorientation grains. These results suggest that the delamination could be reduced by processing the alloys to minimize grain-to-grain property disparities.

Crooks, R.; Domack, M. S.; Wagner, J. A.

2005-01-01

90

Fluid-Dacite Interaction in the PACMANUS Subseafloor Hydrothermal System - Preliminary Results From Secondary Mineral Chemistry and Geochemical Modeling  

NASA Astrophysics Data System (ADS)

During Ocean Drilling Program Leg 193, several holes (as deep as 386 meters below sea floor) intersected variably altered and veined dacites on Pual Ridge in the eastern Manus back-arc basin. The hydothermal alteration is complex and multi-stage, and includes pervasive alteration and alteration halos along anhydrite±pyrite±quartz veins. Our preliminary interpretation is that an early pervasive "chloritic" alteration (chlorite, chlorite/smectite, quartz, +/-albite, +/-magnetite) is overprinted locally by illite-pyrophyllite-anhydrite+/-diaspore alteration followed by silica (quartz and cristobalite) flooding. Two drill holes at Snowcap, a site of diffuse venting, reveal alteration profiles of strongly illite-pyrophyllite-anhydrite altered rocks in the shallow parts grading downwards into rocks that show dominant chloritic alteration. At Roman Ruins, a site of discrete venting, K-feldspar and illite-smectite mixed layer phases are abundant and magnetite is rare. K-feldspar appears to be part of the "chloritic" alteration assemblage. Anhydrite is locally abundant but generally less common than at Snowcap. There is a strong lateral heterogeneity in basement alteration as revealed by the differences between sites in the depths of cristobalite-quartz transition and the zones of prevailing alteration styles. Geochemical modeling suggests that the rocks have been altered at temperatures of about 250 to 300° C under variable fluid-to-rock ratios. While all the mineral assemblages are consistent with quartz/cristobalite saturation of the fluids, the formation of diaspore must be related to episodic interaction of the rocks with fluids highly undersaturated in quartz. The early stage of chloritic alteration represents interaction of the dacites with fluids of a fairly high pH ({>}4). In contrast, the occurrence of pyrophyllite and local diaspore suggests lower pH fluid ({<}3) during later hydrothermal stages. A zone of abundant alunite at 350 m deep in the basement at Snowcap may represent local ingress of very acidic fluids (pH{<}2). Our working hypothesis is that these low-pH fluids indicate significant contributions of a magmatic fluid component that is rich in H2SO4 and HF. Furthermore, the late-stage acidic alteration seems to be more common at Snowcap. Rare-earth element (REE) data from anhydrite veins are consistent with this interpretation. The majority of the anhydrite veins from the Snowcap site display REE patterns that suggest formation of aqueous fluoride and sulfate complexes was important. High F- activities can also be inferred from the presence of minor F-apatite in some anhydrite veins from Snowcap. In contrast, anhydrite from the Roman Ruins site, where evidence for acidic rock alteration style is scarse, shows uniformly light REE enriched patterns.

Yeats, C. J.; Bach, W.; Vanko, D. A.; Roberts, S.; Lackschewitz, K.; Paulick, H.

2001-12-01

91

Response of bone marrow derived connective tissue progenitor cell morphology and proliferation on geometrically modulated microtextured substrates  

PubMed Central

Varying geometry and layout of microposts on a cell culture substrate provides an effective technique for applying mechanical stimuli to living cells. In the current study, the optimal geometry and arrangement of microposts on the polydimethylsiloxane (PDMS) surfaces to enhance cell growth behavior were investigated. Human bone marrow derived connective tissue progenitor cells were cultured on PDMS substrates comprising unpatterned smooth surfaces and cylindrical post microtextures that were 10 µm in diameter, 4 heights (5, 10, 20 and 40 µm) and 3 pitches (10, 20, and 40 µm). With the same 10 µm diameter, post heights ranging from 5 to 40 µm resulted in a more than 535000 fold range of rigidity from 0.011 nNµm?1 (40 µm height) up to 5888 nNµm?1(5 µm height). Even though shorter microposts result in higher effective stiffness, decreasing post heights below the optimal value, 5 µm height micropost in this study decreased cell growth behavior. The maximum number of cells was observed on the post microtextures with 20 µm height and 10 µm inter-space, which exhibited a 675% increase relative to the smooth surfaces. The cells on all heights of post microtextures with 10 µm and 20 µm inter-spaces exhibited highly contoured morphology. Elucidating the cellular response to various external geometry cues enables us to better predict and control cellular behavior. In addition, knowledge of cell response to surface stimuli could lead to the incorporation of specific size post microtextures into surfaces of implants to achieve surface-textured scaffold materials for tissue engineering applications.

Kim, Eun Jung; Fleischman, Aaron J.; Muschler, George F.; Roy, Shuvo

2013-01-01

92

Nanotexturing process on microtextured surfaces of silicon solar cells by SF6/O2 reactive ion etching.  

PubMed

We investigated a nanotexturing process on the microtextured surface of single crystalline silicon solar cell by the reactive ion etching process in SF6/O2 mixed gas ambient. P-type Si wafer samples were prepared using a chemical wet etching process to address saw damage removal and achieve microtexturing. The microtextured wafers were further processed for nanotexturing by exposure to reactive ions within a circular tray of wafer carrier containing many small holes for uniform etching. As the dry etching times were increased to 2, 4 and finally to 8 min, surface structures were observed in a transition from nanoholes to nanorods, and a variation in wafer color from dark blue to black. The surface nanostructures showed a lowered photoreflectance and enhanced quantum efficiency within the visible light region with wavelengths of less than 679 nm. The nanohole structure etched for 2 min showed enhanced conversion efficiency when compared to the bare sample; however, the nanorod structure etched for 8 min exhibited the decreased efficiency with a reduced short circuit current, indicating that the surface nanostructural damage with the enlarged nanoperimetric surface area is sensitive to surface passivation from the surface recombination process. PMID:24266144

Ji, Hyungyong; Choi, Jaeho; Lim, Gyoungho; Parida, Bhaskar; Kim, Keunjoo; Jo, Jung Hee; Kim, Hong Seub

2013-12-01

93

Transformation of heavy metals and the formation of secondary iron minerals during pig manure bioleaching by the co-inoculation acidophilic thiobacillus.  

PubMed

Bioleaching of heavy metals from pig manure using a mixture of harmless iron- and sulfur-oxidizing bacteria in an air-lift reactor was conducted. The transformation of heavy metals and the formation of secondary Fe minerals during bioleaching were also investigated in the present study. The removal efficiencies of Zn, Cu, and Mn from pig manure were 95.1%, 80.9%, and 87.5%, respectively. Zn mainly existed in the form of Fe-Mn oxides in fresh pig manure; most of the pig manure-borne Cu was in organic matter form; Mn existed mainly in Fe-Mn oxides, carbonates, and residual forms. The pig manure can be applied to land more safely after bioleaching because the heavy metals mainly existed in stable forms. The removal efficiencies Zn, Cu, and Mn had good relationships with pH and oxidation reduction potential during bioleaching. A mixture ofjarosite and schwertmannite was found in the bioleached pig manure, which might have an adverse effect on the solubilization efficiency of toxic metals from pig manure. The bioleaching process using a mixture of harmless iron- and sulfur-oxidizing bacteria was shown to be a very feasible technology for the removal of heavy metals from pig manure. PMID:23437654

Zhou, Jun; Zhou, Lixiang; Liu, Fenwu; Zheng, Chaocheng; Deng, Wenjing

2012-12-01

94

Microtextured Omniphobic Surfaces by Solution Spraying of Fluorodecyl POSS/PMMA Blends  

NASA Astrophysics Data System (ADS)

We present a simple technique to prepare various micro-structured surfaces by spray coating a polymer blend of poly(methyl methacrylate) (PMMA) and the low surface energy molecule 1H,1H,2H,2H-heptadecafluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS) using an air brush with a pressurized nitrogen stream. The sprayed surface morphology can be systematically tuned from a spherical or corpuscular microstructure to beads-on-string and a fiborous non-woven mesh, nearly identical to structures obtained by electrospinning similar PMMA/fluorodecyl POSS solutions. A semi-empirical framework is used to develop an operating diagram to predict the surface morphology produced during the simple spraying technique based on the polymer solution concentration and molecular weight. The presence of the low-surface-energy POSS molecules at the surface combined with the re-entrant microtextured features confers super-liquid-repellent properties to the spray-coated substrate, which are characterized by advancing and receding contact angle measurements with liquids of a range of surface tensions.

Srinivasan, Siddarth; McKinley, Gareth; Cohen, Robert

2012-02-01

95

A thermoresponsive, microtextured substrate for cell sheet engineering with defined structural organization  

PubMed Central

The proper function of many tissues depends critically on the structural organization of the cells and matrix of which they are comprised. Therefore, in order to engineer functional tissue equivalents that closely mimic the unique properties of native tissues it is necessary to develop strategies for reproducing the complex, highly organized structure of these tissues. To this end, we sought to develop a simple method for generating cell sheets that have defined ECM/cell organization using microtextured, thermoresponsive polystyrene substrates to guide cell organization and tissue growth. The patterns consisted of large arrays of alternating grooves and ridges (50 ?m wide, 5 ?m deep). Vascular smooth muscle cells cultured on these substrates produced intact sheets consisting of cells that exhibited strong alignment in the direction of the micropattern. These sheets could be readily transferred from patterned substrates to non-patterned substrates without the loss of tissue organization. Ultimately, such sheets will be layered to form larger tissues with defined ECM/cell organization that spans multiple length scales.

Isenberg, Brett C.; Tsuda, Yukiko; Williams, Corin; Shimizu, Tatsuya; Yamato, Masayuki; Okano, Teruo; Wong, Joyce Y.

2008-01-01

96

Natural radionuclide mobility and its influence on U Th Pb dating of secondary minerals from the unsaturated zone at Yucca Mountain, Nevada  

NASA Astrophysics Data System (ADS)

Extreme U and Pb isotope variations produced by disequilibrium in decay chains of 238U and 232Th are found in calcite, opal/chalcedony, and Mn-oxides occurring as secondary mineral coatings in the unsaturated zone at Yucca Mountain, Nevada. These very slowly growing minerals (mm my -1) contain excess 206Pb and 208Pb formed from excesses of intermediate daughter isotopes and cannot be used as reliable 206Pb/ 238U geochronometers. The presence of excess intermediate daughter isotopes does not appreciably affect 207Pb/ 235U ages of U-enriched opal/chalcedony, which are interpreted as mineral formation ages. Opal and calcite from outer (younger) portions of coatings have 230Th/U ages from 94.6 ± 3.7 to 361.3 ± 9.8 ka and initial 234U/ 238U activity ratios (AR) from 4.351 ± 0.070 to 7.02 ± 0.12, which indicate 234U enrichment from percolating water. Present-day 234U/ 238U AR is ˜1 in opal/chalcedony from older portions of the coatings. The 207Pb/ 235U ages of opal/chalcedony samples range from 0.1329 ± 0.0080 to 9.10 ± 0.21 Ma, increase with microstratigraphic depth, and define slow long-term average growth rates of about 1.2-2.0 mm my -1, in good agreement with previous results. Measured 234U/ 238U AR in Mn-oxides, which pre-date the oldest calcite and opal/chalcedony, range from 0.939 ± 0.006 to 2.091 ± 0.006 and are >1 in most samples. The range of 87Sr/ 86Sr ratios (0.71156-0.71280) in Mn-oxides overlaps that in the late calcite. These data indicate that Mn-oxides exchange U and Sr with percolating water and cannot be used as a reliable dating tool. In the U-poor calcite samples, measured 206Pb/ 207Pb ratios have a wide range, do not correlate with Ba concentration as would be expected if excess Ra was present, and reach a value of about 1400, the highest ever reported for natural Pb. Calcite intergrown with opal contains excesses of both 206Pb and 207Pb derived from Rn diffusion and from direct ?-recoil from U-rich opal. Calcite from coatings devoid of opal/chalcedony contains 206Pb and 208Pb excesses, but no appreciable 207Pb excesses. Observed Pb isotope anomalies in calcite are explained by Rn-produced excess Pb. The Rn emanation may strongly affect 206Pb- 238U ages of slow-growing U-poor calcite, but should be negligible for dating fast-growing U-enriched speleothem calcite.

Neymark, L. A.; Amelin, Y. V.

2008-04-01

97

Australian Mineral Foundation.  

ERIC Educational Resources Information Center

Provides details on the philosophy and operation of the Australian Mineral Foundation, established in 1970 to update professionals in the mining and petroleum industries. Services in continuing education courses and to secondary school teachers and students are described. (CS)

Crowe, D. S.

1980-01-01

98

Metal-like conductivity exhibited by triboelectrically deposited polyaniline (emeraldine base) particles on microtextured SiC surfaces  

NASA Astrophysics Data System (ADS)

We demonstrate a simple and rapid way to deposit layers of polyaniline (emeraldine base) particles on flexible microtextured silicon carbide surfaces by contact charging them using a smooth dielectric rubber. Wetting of the layers by trifluoroacetic acid creates conductive, continuous polymeric films after drying. Pre-functionalization of the textured surfaces with anionic surfactants prevents particle coagulation during contact charging and decreases sheet resistance to metal-like levels (~60 ?/\\squarelg). Conductivity of the films can be tuned by controlling the rate of acid evaporation. Conductive films are highly stable under ambient conditions and show no hysteresis when biased with zero delay-time.

Bayer, I. S.; Caramia, V.; Biswas, A.; Cingolani, R.; Athanassiou, A.

2012-05-01

99

Time-temperature evolution of microtextures and contained fluids in a plutonic alkali feldspar during heating  

NASA Astrophysics Data System (ADS)

Microtextural changes brought about by heating alkali feldspar crystals from the Shap granite, northern England, at atmospheric pressure, have been studied using transmission and scanning electron microscopy. A typical unheated phenocryst from Shap is composed of about 70 vol% of tweed orthoclase with strain-controlled coherent or semicoherent micro- and crypto-perthitic albite lamellae, with maximum lamellar thicknesses <1 ?m. Semicoherent lamellae are encircled by nanotunnel loops in two orientations and cut by pull-apart cracks. The average bulk composition of this microtexture is Ab27.6Or71.8An0.6. The remaining 30 vol% is deuterically coarsened, microporous patch and vein perthite composed of incoherent subgrains of oligoclase, albite and irregular microcline. The largest subgrains are ~3 ?m in diameter. Heating times in the laboratory were 12 to 6,792 h and T from 300°C into the melting interval at 1,100°C. Most samples were annealed at constant T but two were heated to simulate an 40Ar/39Ar step-heating schedule. Homogenisation of strain-controlled lamellae by Na?K inter-diffusion was rapid, so that in all run products at >700°C, and after >48 h at 700°C, all such regions were essentially compositionally homogeneous, as indicated by X-ray analyses at fine scale in the transmission electron microscope. Changes in lamellar thickness with time at different T point to an activation energy of ~350 kJmol-1. A lamella which homogenised after 6,800 h at 600°C, therefore, would have required only 0.6 s to do so in the melting interval at 1,100°C. Subgrains in patch perthite homogenised more slowly than coherent lamellae and chemical gradients in patches persisted for >5,000 h at 700°C. Homogenisation T is in agreement with experimentally determined solvi for coherent ordered intergrowths, when a 50-100°C increase in T for An1 is applied. Homogenisation of lamellae appears to proceed in an unexpected manner: two smooth interfaces, microstructurally sharp, advance from the original interfaces toward the mid-line of each twinned, semicoherent lamella. In places, the homogenisation interfaces have shapes reflecting the local arrangements of nanotunnels or pull-aparts. Analyses confirm that the change in alkali composition is also relatively sharp at these interfaces. Si-Al disordering is far slower than alkali homogenisation so that tweed texture in orthoclase, tartan twinning in irregular microcline, and Albite twins in albite lamellae and patches persisted in all our experiments, including 5,478 h at 700°C, 148 h at 1,000°C and 5 h at 1,100°C, even though the ensemble in each case was chemically homogeneous. Nanotunnels and pull-aparts were modified after only 50 min at 500°C following the simulated 40Ar/39Ar step-heating schedule. New features called ‘slots’ developed away from albite lamellae, often with planar traces linking slots to the closest lamella. Slot arrays were often aligned along ghost-like regions of diffraction contrast which may mark the original edges of lamellae. We suggest that the slot arrays result from healing of pull-aparts containing fluid. At 700°C and above, the dominant defects were subspherical ‘bubbles’, which evolved from slots or from regions of deuteric coarsening. The small degree of partial melting observed after 5 h at 1,100°C was often in the vicinity of bubbles. Larger micropores, which formed at subgrain boundaries in patch perthite during deuteric coarsening, retain their shape up to the melting point, as do the subgrain boundaries themselves. It is clear that modification of defects providing potential fast pathways for diffusion in granitic alkali feldspars begins below 500°C and that defect character progressively changes up to, and beyond, the onset of melting.

Parsons, Ian; Fitz Gerald, John D.; Lee, James K. W.; Ivanic, Tim; Golla-Schindler, Ute

2010-08-01

100

High cesium concentrations in groundwater in the upper 1.2 km of fractured crystalline rock - Influence of groundwater origin and secondary minerals  

NASA Astrophysics Data System (ADS)

Dissolved and solid phase cesium (Cs) was studied in the upper 1.2 km of a coastal granitoid fracture network on the Baltic Shield (Äspö Hard Rock Laboratory and Laxemar area, SE Sweden). There unusually high Cs concentrations (up to 5-6 ?g L-1) occur in the low-temperature (<20 °C) groundwater. The material includes water collected in earlier hydrochemical monitoring programs and secondary precipitates (fracture coatings) collected on the fracture walls, as follows: (a) hydraulically pristine fracture groundwater sampled through 23 surface boreholes equipped for the retrieval of representative groundwater at controlled depths (Laxemar area), (b) fracture groundwater affected by artificial drainage collected through 80 boreholes drilled mostly along the Äspö Hard Rock Laboratory (underground research facility), (c) surface water collected in local streams, a lake and sea bay, and shallow groundwater collected in 8 regolith boreholes, and (d) 84 new specimens of fracture coatings sampled in cores from the Äspö HRL and Laxemar areas. The groundwater in each area is different, which affects Cs concentrations. The highest Cs concentrations occurred in deep-seated saline groundwater (median Äspö HRL: 4.1 ?g L-1; median Laxemar: 3.7 ?g L-1) and groundwater with marine origin (Äspö HRL: 4.2 ?g L-1). Overall lower, but variable, Cs concentrations were found in other types of groundwater. The similar concentrations of Cs in the saline groundwater, which had a residence time in the order of millions of years, and in the marine groundwater, which had residence times in the order of years, shows that duration of water-rock interactions is not the single and primary control of dissolved Cs in these systems. The high Cs concentrations in the saline groundwater is ascribed to long-term weathering of minerals, primarily Cs-enriched fracture coatings dominated by illite and mixed-layer clays and possibly wall rock micaceous minerals. The high Cs concentrations in the groundwater of marine origin are, in contrast, explained by relatively fast cation exchange reactions. As indicated by the field data and predicted by 1D solute transport modeling, alkali cations with low-energy hydration carried by intruding marine water are capable of (NH4+ in particular and K+ to some extent) replacing Cs+ on frayed edge (FES) sites on illite in the fracture coatings. The result is a rapid and persistent (at least in the order of decades) buildup of dissolved Cs concentrations in fractures where marine water flows downward. The identification of high Cs concentrations in young groundwater of marine origin and the predicted capacity of NH4+ to displace Cs from fracture solids are of particular relevance in the disposal of radioactive nuclear waste deep underground in crystalline rock.

Mathurin, Frédéric A.; Drake, Henrik; Tullborg, Eva-Lena; Berger, Tobias; Peltola, Pasi; Kalinowski, Birgitta E.; Åström, Mats E.

2014-05-01

101

Cryptic microtextures and geological histories of K-rich alkali feldspars revealed by charge contrast imaging  

NASA Astrophysics Data System (ADS)

Charge contrast imaging in the scanning electron microscope can provide new insights into the scale and composition of alkali feldspar microtextures, and such information helps considerably with the interpretation of their geological histories and results of argon isotope thermochronological analyses. The effectiveness of this technique has been illustrated using potassium-rich alkali feldspars from the Dartmoor granite (UK). These feldspars contain strain-controlled lamellar crypto- and microperthites that are cross-cut by strain-free deuteric microperthites. The constituent albite- and orthoclase-rich phases of both microperthite generations can be readily distinguished by atomic number contrast imaging. The charge contrast results additionally show that sub-micrometre-sized albite `platelets' are commonplace between coarser exsolution lamellae and occur together to make cryptoperthites. Furthermore, charge contrast imaging reveals that the orthoclase-rich feldspar is an intergrowth of two phases, one that is featureless with uniform contrast and another that occurs as cross-cutting veins and grains with the {110} adularia habit. Transmission electron microscopy shows that the featureless feldspar is tweed orthoclase, whereas the veins and euhedral grains are composed of irregular microcline that has formed from orthoclase by `unzipping' during deuteric or hydrothermal alteration. The charge contrast imaging results are especially important in demonstrating that deuteric perthites are far more abundant in alkali feldspars than would be concluded from investigations using conventional microscopy techniques. The unexpected presence of such a high volume of replacement products has significant implications for understanding the origins and geological histories of crustal rocks and the use of alkali feldspars in geo- and thermochronology. Whilst the precise properties of feldspars that generate contrast remain unclear, the similarity between charge contrast images and corresponding cathodoluminescence images of deuteric microperthites indicates that trace element chemistry and possibly also elastic strain within the crystal play a major role.

Flude, Stephanie; Lee, Martin R.; Sherlock, Sarah C.; Kelley, Simon P.

2012-06-01

102

A three dimensional scaffold with precise micro-architecture and surface micro-textures  

PubMed Central

A three-dimensional (3D) structure comprising precisely defined microarchitecture and surface micro-textures, designed to present specific physical cues to cells and tissues, may provide an efficient scaffold in a variety of tissue engineering and regenerative medicine applications. We report a fabrication technique based on microfabrication and soft lithography that permits for the development of 3D scaffolds with both precisely engineered architecture and tailored surface topography. The scaffold fabrication technique consists of three key steps starting with microfabrication of a mold using an epoxy-based photoresist (SU-8), followed by dual-sided molding of a single layer of polydimethylsiloxane (PDMS) using a mechanical jig for precise motion control; and finally, alignment, stacking, and adhesion of multiple PDMS layers to achieve a 3D structure. This technique was used to produce 3D Texture and 3D Smooth PDMS scaffolds, where the surface topography comprised 10 ?m-diameter/height posts and smooth surfaces, respectively. The potential utility of the 3D microfabricated scaffolds, and the role of surface topography, were subsequently investigated in vitro with a combined heterogeneous population of adult human stem cells and their resultant progenitor cells, collectively termed connective tissue progenitors (CTPs), under conditions promoting the osteoblastic phenotype. Examination of bone-marrow derived CTPs cultured on the 3D Texture scaffold for 9 days revealed cell growth in three dimensions and increased cell numbers compared to those on the 3D Smooth scaffold. Furthermore, expression of alkaline phosphatase mRNA was higher on the 3D Texture scaffold, while osteocalcin mRNA expression was comparable for both types of scaffolds.

Mata, Alvaro; Kim, Eun Jung; Boehm, Cynthia A.; Fleischman, Aaron J.; Muschler, George F.; Roy, Shuvo

2013-01-01

103

Effects of bound phosphate on the bioreduction of lepidocrocite (?-FeOOH) and maghemite (?-Fe2O3) and formation of secondary minerals.  

PubMed

Natural Fe(III) oxides typically contain a range of trace elements including P. Although solution phase and adsorbed P (as phosphate) have been shown to impact the bioreduction of Fe(III) oxides and the formation of "biogenic" secondary minerals, little is known about the potential effects of occluded/incorporated phosphate. We have examined the bioreduction of Fe(III) oxides (lepidocrocite (?-FeOOH) and maghemite (?-Fe2O3)) containing 0-3 mass% P as "bound" (a term we use to include both adsorbed and occluded/incorporated) phosphate. Kinetic dissolution studies showed congruent release of Fe and P, suggesting that the phosphate in these materials was incorporated within the particles; however, 53% or 86% of the total phosphate associated with the lepidocrocites containing 0.7 or 3 mass% P, respectively, was extracted with 0.1 M NaOH and can be considered to be adsorbed, both to exterior surfaces and within micropores. In the absence of phosphate, lepidocrocite was rapidly reduced to magnetite by Shewanella putrefaciens CN32, and over time the magnetite was partially transformed to ferrous hydroxy carbonate (FHC). The presence of 0.2-0.7 mass% P significantly inhibited the initial reduction of lepidocrocite but ultimately resulted in greater Fe(II) production and the formation of carbonate green rust. The bioreduction of maghemite with and without bound phosphate resulted in solid-state conversion to magnetite, with subsequent formation of FHC. We also examined the potential redox cycling of green rust under alternating Fe(III)-reducing and oxic conditions. Oxidation of biogenic green rust by O2 resulted in conversion to ferric green rust, which was readily reduced back to green rust by S. putrefaciens CN32. These results indicate the potential for cycling of green rust between reduced and oxidized forms under redox dynamics similar to those encountered in environments that alternate between iron-reducing and oxic conditions, and they are consistent with the identification of green rust in soils/sediments with seasonal redox cycling. PMID:23909690

O'Loughlin, Edward J; Boyanov, Maxim I; Flynn, Theodore M; Gorski, Christopher A; Hofmann, Scott M; McCormick, Michael L; Scherer, Michelle M; Kemner, Kenneth M

2013-08-20

104

Compositional and quantitative microtextural characterization of historic paintings by micro-X-ray diffraction and Raman microscopy.  

PubMed

This work shows the benefits of characterizing historic paintings via compositional and microtextural data from micro-X-ray diffraction (?-XRD) combined with molecular information acquired with Raman microscopy (RM) along depth profiles in paint stratigraphies. The novel approach was applied to identify inorganic and organic components from paintings placed at the 14th century Islamic University-Madrasah Yusufiyya-in Granada (Spain), the only Islamic University still standing from the time of Al-Andalus (Islamic Spain). The use of ?-XRD to obtain quantitative microtextural information of crystalline phases provided by two-dimensional diffraction patterns to recognize pigments nature and manufacture, and decay processes in complex paint cross sections, has not been reported yet. A simple Nasrid (14th century) palette made of gypsum, vermilion, and azurite mixed with glue was identified in polychromed stuccos. Here also a Christian intervention was found via the use of smalt, barite, hematite, Brunswick green and gold; oil was the binding media employed. On mural paintings and wood ceilings, more complex palettes dated to the 19th century were found, made of gypsum, anhydrite, barite, dolomite, calcite, lead white, hematite, minium, synthetic ultramarine blue, and black carbon. The identified binders were glue, egg yolk, and oil. PMID:21981573

Romero-Pastor, Julia; Duran, Adrian; Rodríguez-Navarro, Alejandro Basilio; Van Grieken, René; Cardell, Carolina

2011-11-15

105

Enumeration of Thiobacilli within pH-Neutral and Acidic Mine Tailings and Their Role in the Development of Secondary Mineral Soil  

PubMed Central

The Lemoine tailings of Chibougamau, Quebec, Canada, were deposited as a pH-neutral mineral conglomerate consisting of aluminum-silicates, iron-aluminum-silicates, pyrite, chalcopyrite, and sphalerite. These tailings are colonized by an active population of Thiobacillus ferrooxidans which is localized to an acid zone occupying 40% of the tailings' surface. This population peaked at 7 × 108 most probable number per gram of tailings during July and August 1990 and extended to a depth of 40 cm from the surface. Examination of samples over this depth profile by transmission electron microscopy and electron dispersive spectroscopy revealed a microbially mediated mineral transition from sulfides (below 40 cm) to chlorides and phosphates (at the surface). Silicate minerals were unaltered by microbial action. Transmission electron microscopy showed a tight association between Thiobacillus species and the sulfide minerals, which helps account for their prominence in tailings environments. Accurate enumeration of T. ferrooxidans from tailings required the disruption of their bonding to the mineral interface. Vortexing of a 10% aqueous suspension of the tailings material prior to most-probable-number analysis best facilitated this release. Even though heavy metals were highly mobile under acidic conditions at the Lemoine tailings, it was evident by transmission electron microscopy and electron dispersive spectroscopy that they were being immobilized as bona fide fine-grain minerals containing iron, copper, chlorine, phosphorus, and oxygen on bacterial surfaces and exopolymers. This biomineralization increased with increasing bacterial numbers and was most evident in the upper 3 cm of the acidic zone. Images

Southam, G.; Beveridge, T. J.

1992-01-01

106

Kinetics and microtextures formation during serpentinization: role of grain scale processes and transport  

NASA Astrophysics Data System (ADS)

Serpentinization of mantle rocks plays a key role on the physical properties of the lithosphere at mid-ocean ridges and in subduction zones. This reaction is controlled by processes occurring at scales ranging from the grain to the lithosphere but the relative importance of these processes on the kinetics and microtextures formation has not been investigated. First, hydrothermal experiments on powders of San Carlos olivine at 500 bars in the 250 - 350 °C range were monitored with a magnetic method to study the kinetics and processes of the reaction at the grain scale. For an initial grain size (IGS) > 5 ?m, lizardite, brucite, magnetite and hydrogen formed at a rate one to two orders of magnitude slower than the kinetics used to model serpentinization-related processes. Moreover, the serpentinization rate decreased linearly with the square of the IGS and reaction progress vs. time curves displayed a sigmoid form. The kinetics were controlled by the dissolution of olivine increasing with its reactive surface area which was generated with two cooperating processes (etch pits and grain fracturing) during the first stages of the reaction. Then, hydrothermal experiments were conducted on sintered San Carlos olivine to investigate the role of transport on the reaction. On sintered with a grain size of 1 to 5 ?m, low reaction progresses of ~ 3 % in 10 months were obtained and the rate of serpentinization was one order of magnitude slower than on powders and one order of magnitude faster than on a single grain of the size of the sintered. Kinetics were controlled by a coupling between the reaction rate at the grain scale and the rate of fluid pathways formation at grain boundaries. Lizardite precipitated where olivine dissolved whereas magnetite and brucite segregated at the surface of the sintered. These results are in agreement with the observation of magnetite formation and segregation in fractures in naturally serpentinized peridotites and could explain the sparse description of brucite in these rocks. Thermodynamical modelling shows that a removal of brucite in serpentinized peridotites could explain the loss of 10 % of the Mg measured in oceanic peridotites [1, 2]. [1] Snow, J.E. and H.J.B. Dick (1995) Pervasive magnesium loss by marine weathering of peridotites, Geochim. Cosmochim. Acta, 59, 4219-4235. [2] Niu, Y. (2004) Bulk-rock major and trace element compositions of abyssal peridotites: implications for mantle melting, melt extraction and post-melting processes beneath mid-ocean ridges, J. Petrol., 45, 2423-2458.

malvoisin, B.; Brunet, F.; Carlut, J. H.

2013-12-01

107

Micro-texture and Structure of High-pressure Quenched Graphite and Related Carbon Materials  

NASA Astrophysics Data System (ADS)

There have been extensive studies in room-temperature compression of graphite and related carbon materials such as nanotubes and fullerene. Some reports claimed that the transformation of carbon hybridized state from sp2 to sp3 takes place under high pressure at room temperature, and the hardness of the quench products may be comparable to that of cubic diamond. Here, we investigated the micro-texture and structure involved in such high-pressure quenched carbon materials using high-resolution electron microscopy. High- pressure experiments were conducted on a variety of carbon materials including graphite (synthetic, highly- oriented sheet), single/multi-walled carbon nanotubes, amorphous carbons in a diamond anvil cell (DAC, with 250 ?m culet non-beveled anvils) at room temperature. Pelletized sample was loaded into a 70 ?m hall, drilled in a preindented Re gasket, without a pressure medium. The sample was compressed up to 70 ~ 90 GPa at room temperature, kept at the highest pressure at least overnight, and then decompressed. The pressure dependence of graphite E2g( G) Raman band at ~1580cm-1 was measured on compression and decompression. A1g( D) band, so called defect band at ~1350 cm-1, was also collected for the recovered products. The quenched materials were examined by high-resolution (HR) field emission (FE-) SEM and (HR)TEM. A focused ion beam (FIB) was employed to fabricate thin cross-sections of the samples. The most notable change in texture upon compression was observed in multi-walled carbon nanotube (MWNT); the elongated tubes were fragmented into short rods (ca. 100 - 300 nm in length and 80 - 100 nm in width, almost two times wider than that of the original MWNT). TEM observations showed that the short rod- shaped particles consist of piles of graphene shells (stacked walls of MWNT, characterized by (002) lattice fringes) which were significantly bent and fragmented. Some of those rod-shaped particles showed lattice fringes with an interlayer spacing of ca. 2 Å at the core regions, which may be derived from a high-pressure phase of carbon. More detailed textural observations and structural analysis based on electron diffraction are works in progress.

Ohfuji, H.; Aibara, K.; Sumiya, H.; Irifune, T.

2007-12-01

108

30 CFR 56.3400 - Secondary breakage.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Secondary breakage. 56.3400 Section 56.3400 Mineral Resources...Control Precautions § 56.3400 Secondary breakage. Prior to secondary breakage operations, material to be broken,...

2010-07-01

109

30 CFR 57.3400 - Secondary breakage.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Secondary breakage. 57.3400 Section 57.3400 Mineral Resources...Precautions-Surface and Underground § 57.3400 Secondary breakage. Prior to secondary breakage operations, the material to be broken,...

2010-07-01

110

The distribution of secondary mineral phases along an eroding hillslope and its effect on carbon stabilization mechanisms and the fate of soil carbon fractions  

NASA Astrophysics Data System (ADS)

Soil redistribution processes can change soil carbon (C) dynamics drastically by moving carbon from high decomposition and re-sequestration environments at the eroding hillslope to low decomposition and burial at the depositional footslope and valley basin. This leads to not only spatially diverse soil carbon storage throughout the landscape, but also to qualitative changes of the transported carbon and the mineral phase. The interaction between those parameters and the effect on stabilization mechanisms for soil C are still a matter of debate. Here, we present an analysis that aims to clarify the bio/geo-chemical and mineralogical components involved in stabilizing C at various depths along an eroding cropped slope and how this affects the abundance of microbial derived carbon. We use the results of an incubation experiment combined with the abundance of amino sugars in different isolated soil C fractions as a tracer for the stability of the respective fraction. We applied further (i) a sequential extraction of the reactive soil phase using pyrophosphate, oxalate and dithionite-citrate-bicarbonate, and (ii) a qualitative analysis of the clay mineralogy, to analyze the changes in the mineral phase for the different isolated fractions along the slope transect. Our results emphasize the importance of physical protection within microaggregates to stabilize buried, chemically labile C. Our data further indicates that the stability of these aggregates is related to the presence of organo-mineral associations and poorly crystalline minerals. However, decreasing contents of these minerals with depth indicate a temporal limitation of this stabilization mechanism. Non-expandable clay minerals experience a relative enrichment at the depositional site while expandable clay minerals experience the same at the eroding site. These changes in clay mineralogy along the slope are partly responsible for the abundance of silt and clay associated C and the effectiveness of the clay fractions to stabilize C. In summary, our data clearly show that a variety of stabilization mechanisms together with changes in the organic and the mineral phase of soils need to be considered to understand this highly dynamic environment.

Doetterl, Sebastian; Cornelis, Jean-Thomas; Opfergelt, Sophie; Boeckx, Pascal; Bodé, Samuel; Six, Johan; Van Oost, Kristof

2014-05-01

111

Chemical composition, plant secondary metabolites, and minerals of green and black teas and the effect of different tea-to-water ratios during their extraction on the composition of their spent leaves as potential additives for ruminants.  

PubMed

This study characterized the chemical composition of green and black teas as well as their spent tea leaves (STL) following boiling in water with different tea-to-water ratios. The green and black tea leaves had statistically similar (g/kg dry matter (DM), unless stated otherwise) DM (937 vs 942 g/kg sample), crude protein (240 vs 242), and ash (61.8 vs 61.4), but green tea had significantly higher (g/kg DM) total phenols (231 vs 151), total tannins (204 vs 133), condensed tannins (176 vs 101), and total saponins (276 vs 86.1) and lower neutral detergent fiber (254 vs 323) and acid detergent fiber (211 vs 309) than the black tea leaves. There was no significant difference between the green and black tea leaves for most mineral components except Mn, which was significantly higher in green tea leaves, and Na and Cu, which were significantly higher in black tea leaves. A higher tea-to-water ratio during extraction significantly reduced the loss of soluble compounds into water and hence yielded more nutrient-rich STL. On the basis of these analyses it appears that the green and black tea leaves alongside their STL have the potential for use as sources of protein, fiber, secondary metabolites, and minerals in ruminant diets. The presence of high levels of plant secondary metabolites in either tea leaves or their STL suggests that they may have potential for use as natural additives in ruminant diets. PMID:23621359

Ramdani, Diky; Chaudhry, Abdul Shakoor; Seal, Chris J

2013-05-22

112

Fluid/mineral interaction in mantle wedge garnet peridotites  

NASA Astrophysics Data System (ADS)

We present two case studies of metasomatised garnet peridotite from the Sulu (Zhimafang) and of garnet orthopyroxenite from the Dabie Shan (Maowu) ultrahigh-pressure terranes (Eastern China). The mantle derived peridotite from Zhimafang shows two ultrahigh-pressure (UHP) mineral assemblages. The older one is made of porphyroclastic garnet rich in inclusions (Grt1), coarse exsolved clinopyroxene (Cpx1) and coarse phlogopite flakes (Phl1). The younger paragenesis consists of fine-grained olivine + clinopyroxene (Cpx2) + orthopyroxene ± magnesite ± Phl2 equilibrated with neoblastic garnet (Grt2). The inclusions inside porphyroclastic Grt1 are polyphase secondary inclusions related to microfractures cutting the garnet core. They display irregular shapes and contain microcrystals of calcic-amphibole, chlorite, phlogopite and rare talc, associated with pyrite and/or spinel. The low Al2O3 content (<0.2 wt.%) in orthopyroxene coexisting with garnets and clinopyroxenes indicates equilibration at P=4.0-6.0 GPa and T=700-1000 °C. The trace element composition of Cpx1 and Phl1 combined with previous petrologic and isotopic data suggests that the Zhimafang garnet peridotite experienced metasomatism by a melt with alkaline character at high-temperature conditions (T=1000 °C and P>5.0 GPa). The microtextural identification of pseudosecondary inclusions in the porphyroclastic garnet core and their geochemical characterisation indicate that an incompatible element- and silicate-rich fluid subsequently metasomatised the garnet peridotite and equilibrated with the newly formed Cpx2 probably during Triassic UHP metamorphism. Ultramafic metasomatic layers at Maowu Ultramafic Complex (Dabie Shan) consist of layered websterite and orthopyroxenite which preserve an old olivine + orthopyroxene (Opx1) + garnet (Grt1) ± Ti-clinohumite paragenesis, overgrown by poikilitic Opx2. Grt2 is associated with Opx2 + phlogopite along the foliation, together with fine-grained idiomorphic clinopyroxene. Grt2 cores contain disseminated primary polyphase inclusions. The textural and geochemical analyses of the primary polyphase inclusions indicate that they derive from a homogeneous fluid characterised by high LILE concentrations with spikes in Cs, Ba, Pb and high U/Th. These inclusions are interpreted as remnants of the LILE- and LREE-enriched residual fluid produced when a crust derived Si-rich metasomatic agent reacted with a previous harzburgite to form garnet orthopyroxenite. The in situ trace element analyses of the major phases garnet, clinopyroxene and phlogopite that formed at the same time as the polyphase inclusions at Maowu, permit the determination of empirical mineral/fluid partitioning at pressures relevant for element recycling in subduction zones. Our estimated D(Cpx/fluid) suggests that all LILE are highly incompatible, Th and U are moderately incompatible, Pb is close to unity and Sr is moderately compatible. Phlogopite preferentially incorporates Rb and K with respect to Ba and Cs, and Th with respect to U. The similarity between the residual Maowu fluid with the secondary inclusions in the UHP wedge-type garnet peridotite from Sulu, indicates that the fluids produced from reactions at the slab-mantle interface may be effective metasomatic agents in the mantle wedge. Such reactions may produce phlogopite, which plays an important role in controlling the LILE characteristics of the slab-derived fluid in subduction zones.

Malaspina, Nadia; Scambelluri, Marco; Hermann, Jörg

2010-05-01

113

Fluid/mineral interaction in UHP garnet peridotite  

NASA Astrophysics Data System (ADS)

We present two case studies of metasomatised garnet peridotite from the Sulu (Zhimafang) and of garnet orthopyroxenite from the Dabie Shan (Maowu) ultrahigh-pressure terranes (Eastern China). The mantle-derived peridotite from Zhimafang shows two ultrahigh-pressure (UHP) mineral assemblages. The older one is made of porphyroclastic garnet rich in inclusions (Grt 1), coarse exsolved clinopyroxene (Cpx 1) and coarse phlogopite flakes (Phl 1). The younger paragenesis consists of fine-grained olivine + clinopyroxene (Cpx 2) + orthopyroxene ± magnesite ± Phl 2 equilibrated with neoblastic garnet (Grt 2). The inclusions inside porphyroclastic Grt 1 are polyphase secondary inclusions related to microfractures cutting the garnet core. They display irregular shapes and contain microcrystals of calcic-amphibole, chlorite, phlogopite and rare talc, associated with pyrite and/or spinel. The low Al 2O 3 content (< 0.2 wt.%) in orthopyroxene coexisting with garnets and clinopyroxenes indicates equilibration at P = 4.0-6.0 GPa and T = 700-1000 °C. The trace element composition of Cpx 1 and Phl 1 combined with the petrologic and isotopic data of Yang and Jahn [Yang, J.J., Jahn, B.M., 2000. Deep subduction of mantle-derived garnet peridotites from the Su-Lu UHP metamorphic terrane in China. Journal of Metamorphic Geology 18, 167-180.] suggests that the Zhimafang garnet peridotite experienced metasomatism by a melt with alkaline character at high-temperature conditions ( T ˜ 1000 °C and P > 5.0 GPa). The microtextural identification of pseudosecondary inclusions in the porphyroclastic garnet core and their geochemical characterisation indicate that an incompatible element- and silicate-rich fluid subsequently metasomatised the garnet peridotite and equilibrated with the newly formed Cpx 2 probably during Triassic UHP metamorphism. Ultramafic metasomatic layers at Maowu Ultramafic Complex (Dabie Shan) consist of layered websterite and orthopyroxenite which preserve an old olivine + orthopyroxene (Opx 1) + garnet (Grt 1) ± Ti-clinohumite paragenesis, overgrown by poikilitic Opx 2. Grt 2 is associated with Opx 2 + phlogopite along the foliation, and fine-grained idiomorphic clinopyroxene also occurs. Grt 2 cores contain disseminated primary polyphase inclusions. The textural and geochemical analyses of the primary polyphase inclusions indicate that they derive from a homogeneous fluid characterised by high LILE concentrations with spikes in Cs, Ba, Pb and high U/Th. These inclusions are interpreted as remnants of the LILE- and LREE-enriched residual fluid produced when a crust-derived Si-rich metasomatic agent reacted with a previous harzburgite to form garnet orthopyroxenite. The in-situ trace element analyses of the major phases garnet, clinopyroxene and phlogopite that formed at the same time as the polyphase inclusions at Maowu, permit the determination of empirical mineral/fluid partitioning at pressures relevant for element recycling in subduction zones. Our estimated DCpx/fluid suggests that all LILE are highly incompatible, Th and U are moderately incompatible, Pb is close to unity and Sr is moderately compatible. Phlogopite preferentially incorporates Rb and K with respect to Ba and Cs, and Th with respect to U. The similarity between the residual Maowu fluid with the secondary inclusions in the UHP wedge-type garnet peridotite from Sulu, indicates that the fluids produced from reactions at the slab-mantle interface may be effective metasomatic agents in the mantle wedge. Such reactions may produce phlogopite, which plays an important role in controlling the LILE characteristics of the slab-derived fluid in subduction zones.

Malaspina, Nadia; Hermann, Jörg; Scambelluri, Marco

2009-01-01

114

Relating rheological measurements to primary and secondary skin feeling when mineral-based and Fischer-Tropsch wax-based cosmetic emulsions and jellies are applied to the skin.  

PubMed

Rheology measurements were correlated to skin sensations occurring when cream and petroleum jelly cosmetic products containing different amounts of synthetic Fischer-Tropsch wax were applied to the skin. A panel of 15 people with a background in cosmetic product development were asked to rate skin feelings when a range of petroleum jelly and cream samples are applied to the skin. Primary skin feel, or the spreadability of a cosmetic product, was correlated to the product's flow onset and maximum viscosity as measured by a Anton Paar rheometer, whereas secondary skin feel or the sensation occurring at the end of application when the product was completely rubbed into the skin was correlated to the product's viscosity measured at high shear rates. The cream samples prepared with a petroleum jelly containing 10% and 20% Fischer-Tropsch wax fell within the boundary of good primary skin feeling of cream products. Predominantly, synthetic petroleum jellies were given the best assessments in terms of primary skin feeling and were used with mineral-based petroleum jellies to determine the boundary of good primary skin feeling for petroleum jelly products. The further away a product falls from this rheological boundary the poorer the skin feeling assessment appears to be by the panel. Products containing Fischer-Tropsch waxes were given the best assessment by the panel for secondary skin feeling. Comments from the panel include that these products feel silky and light on the skin. The higher the Fischer-Tropsch wax content, the lower viscosity was at high shear rate (? = 500 s(-1) ) and the higher the assessment by the panel. Rheological measurements can be used to objectively determine skin sensation when products are applied to the skin; this may shorten research and development times. A rheology boundary of certain product viscosity and shear stress applied is associated with good primary skin feeling for lotions, creams and petroleum jellies. Lower product viscosity at high shear rate seems to be associated with better secondary skin feeling. Products with higher Fischer-Tropsch wax content appear to be rated higher in terms of secondary skin feeling. PMID:23551222

Bekker, M; Webber, G V; Louw, N R

2013-08-01

115

Mineral Properties  

NSDL National Science Digital Library

You will learn about the properties that will help you identify minerals. If you closed your eyes and tasted different foods, you could probably determine what the foods are by noting properties such as saltiness or sweetness. You can also determine the identity of a mineral by noting different properties. Some properties that help us determine the identy of a mineral are: COLOR, ...

Wood, Mr.

2010-11-14

116

Mineral Identification  

NSDL National Science Digital Library

Imagine you are hiking with your family and this shiney looking crystal catches your eye. You bring it home and no one in your family is able to tell you what it is. How do you find out? First you need to practice. Identifying minerals. Click on the following link. Identify all five minerals. On your peice of paper tell me their Name Color Luster Cleavage/Fracture Hardness Glenco simple mineral identification Now try and identify 7 real minerals using a virtual key. Answer the following questions What properties do you use to identify the mineral? Which ...

Rmesser

2010-11-16

117

Reply to 'Commentary: Assessment of past infiltration fluxes through Yucca Mountain on the basis of the secondary mineral record-is it a viable methodology?', by Y.V. Dublyansky and S.Z. Smirnov  

SciTech Connect

Xu et al. (2003) presented results of a reaction-transport model for calcite deposition in the unsaturated zone at Yucca Mountain, and compared the model results to measured abundances in core from a surface-based borehole. Marshall et al. (2003) used the calcite distribution in the Topopah Spring Tuff to estimate past seepage into lithophysal cavities as an analog for seepage into the potential repository waste emplacement drifts at Yucca Mountain in southern Nevada (USA). Dublyansky and Smirnov (2005) wrote a commentary paper to Marshall et al. (2003) and Xu et al. (2003), containing two points: (1) questionable phenomenological model for the secondary mineral deposits and (2) inappropriate thermal boundary conditions. In this reply we address primarily the modeling approach by showing results of a sensitivity simulation regarding the effect of an elevated temperature history that approximates the temperature history inferred from fluid inclusions by Wilson et al. (2003). Modeled calcite abundances using the time-varying temperature history are similar to the results for the steady-state ambient temperature profile (Xu et al., 2003), and are still consistent with the measured abundances at the proposed repository horizon.

Sonnenthal, Eric; Xu, Tianfu; Bodvarrson, Gudmundur

2005-03-14

118

Pyrophanite pseudomorphs after perovskite in Perkupa serpentinites (Hungary): a microtextural study and geological implications  

NASA Astrophysics Data System (ADS)

Pyrophanite in serpentinite at Perkupa (Hungary) is described in detail for the first time as a replacement product of perovskite. It occurs as a 20- to 30-?m-wide rim, mantling a remnant core composed of perovskite or its alteration products. The pyrophanite rim consists of an inner zone, representing a pseudomorph after perovskite, and an outer overgrowth zone. Raman mapping and electron backscatter diffraction data show that the pyrophanite rims typically represent single crystals rather than being composed of multiple domains in different crystallographic orientations. Perovskite occurs exclusively in the core of pyrophanite and was identified as the orthorhombic CaTiO3 phase, based on Raman spectra. Heterogeneous, polyphase mineral cores, consisting of calcite, anatase and/or brookite, kassite, and Mn-bearing kassite, in some cases in association with relict perovskite, are typical in the larger pyrophanite-rimmed grains. The crystallographically coherent pyrophanite rims could have formed through a process where the precursor perovskite crystal acted as a structural template for the newly forming phase, that is, by interface-coupled dissolution reprecipitation during serpentinization of the precursor rock. This alteration of perovskite to pyrophanite was not complete, resulting in the presence of perovskite fragments enclosed in pyrophanite. During the metamorphic evolution of the rock, some of the remnant perovskite cores further altered to TiO2 polymorphs (anatase and brookite) and calcite, via transitional alteration products.

Zajzon, N.; Váczi, T.; Fehér, B.; Takács, Á.; Szakáll, S.; Weiszburg, T. G.

2013-09-01

119

Mineral slurries  

SciTech Connect

A pumpable slurry of mineral particles, e.g., coal, in water contains 50 to 85% by weight of mineral particles based on the combined weight of mineral particles and water. The mineral component contains at least 30% by weight of coarse particles having a particle size in the range 5 to 50 mm, 10 to 40% by weight of fine particles having a particle size less than 200 micron and the balance to 100% of intermediate sized particles. The slurry is stable without the use of additives and can be pumped through a pipeline.

Baker, P.J.; Brookes, D.A.; Johnson, M.

1985-06-25

120

Micro-Textured Milky ZnO:Ga Thin Films Fabricated by Pulsed Laser Deposition Using Second-Harmonic-Generation of Nd:YAG Laser  

NASA Astrophysics Data System (ADS)

Approximately 800-nm-thick ZnO films doped with 4 wt% Ga2O3 (GZO films) have been deposited on glass and quartz substrates by a pulsed laser deposition method using Second-Harmonic-Genreation (SHG) of Nd:YAG laser (?=532 nm). In all experiments, a repetition rate of 10 Hz, energy densities of 0.1 2.5 J/cm2, and irradiation times of 2 3 h were used. Scanning Electron Microscopy (SEM) observations of the film surface revealed that there were micro-textured structures (0.5 1 µm in diameter), surrounded by small rugged and irregular structures (250 400 nm in size). It was recognized from XRD spectra that a strong peak of (103) planes reflected from the micro-textured milky surfaces is dominant. A haze ratio of 46.6 % was obtained at a wavelength of 550 nm for approximately 800-nm-thick GZO (4 wt%) films grown at a substrate temperature of 300 °C in oxygen with a flow rate of 3 sccm. The lowest resistivity of 2.33×10-4 ?·cm and the lowest sheet resistance of 2.72 ?/sq were obtained for these GZO (4 wt%) films.

Suzuki, Akio; Matsushita, Tatsuhiko; Aoki, Takanori; Yoneyama, Yoshitaka; Okuda, Masahiro

1999-01-01

121

Extraterrestrial magnetic minerals  

NASA Astrophysics Data System (ADS)

Thermomagnetic and microprobe analyses are carried out and a set of magnetic characteristics are measured for 25 meteorites and 3 tektites from the collections of the Vernadsky Geological Museum of the Russian Academy of Sciences and Museum of Natural History of the North-East Interdisciplinary Science Research Institute, Far Eastern Branch of the Russian Academy of Sciences. It is found that, notwithstanding their type, all the meteorites contain the same magnetic minerals and only differ by concentrations of these minerals. Kamacite with less than 10% nickel is the main magnetic mineral in the studied samples. Pure iron, taenite, and schreibersite are less frequent; nickel, various iron spinels, Fe-Al alloys, etc., are very rare. These minerals are normally absent in the crusts of the Earth and other planets. The studied meteorites are more likely parts of the cores and lower mantles of the meteoritic parent bodies (the planets). Uniformity in the magnetic properties of the meteorites and the types of their thermomagnetic (MT) curves is violated by secondary alterations of the meteorites in the terrestrial environment. The sediments demonstrate the same monotony as the meteorites: kamacite is likely the only extraterrestrial magnetic mineral, which is abundant in sediments and associated with cosmic dust. The compositional similarity of kamacite in iron meteorites and in cosmic dust is due to their common source; the degree of fragmentation of the material of the parent body is the only difference.

Pechersky, D. M.; Markov, G. P.; Tsel'movich, V. A.; Sharonova, Z. V.

2012-07-01

122

Mineral Identification  

NSDL National Science Digital Library

In this activity, students use written and online materials to answer a set of questions on the general properties and identification of minerals. They will learn about physical properties such as color, hardness, and cleavage; special properties such as fluorescence and effervescence; and complete a chart listing properties for a selection of minerals. Links to the necessary information are provided.

Passow, Michael

123

Flourescent Minerals  

NSDL National Science Digital Library

This web page, hosted by Microscopy-UK, provides illustrations of flourescent minerals, each with accompanying text that shows how the color identifies the mineral. The site offers a brief explanation of flourescence and uses examples of calcite, willemite, and flourite to demonstrate this phenomenon. Numerous images, diagrams, and links are provided.

2009-01-28

124

Mineral Densities  

NSDL National Science Digital Library

Students are given cubic cell edge dimensions and asked to calculate mineral densities and vice versa. The final question of this homework assignment provides students with a mineral density and unit cell edge length in order to determine the number of formula units per cell.

125

Compositional and Microtextural Analysis of Basaltic Feedstock Materials Used for the 2010 ISRU Field Tests, Mauna Kea, Hawaii  

NASA Astrophysics Data System (ADS)

This study seeks to understand variations in composition and texture of basaltic pyroclastic materials used in the 2010 International Lunar Surface Operation-In-Situ Resource Utilization Analogue Test (ILSO-ISRU) held on the slopes of Mauna Kea Volcano, Hawaii (1). The quantity and quality of resources delivered by ISRU depends upon the nature of the materials processed (2). We obtained a one-meter deep auger cuttings sample of a basaltic regolith at the primary site for feed stock materials being mined for the ISRU field test. The auger sample was subdivided into six, ~16 cm depth increments and each interval was sampled and characterized in the field using the Multispectral Microscopic Imager (MMI; 3) and a portable X-ray Diffractometer (Terra, InXitu Instruments, Inc.). Splits from each sampled interval were returned to the lab and analyzed using more definitive methods, including high resolution Powder X-ray Diffraction and Thermal Infrared (TIR) spectroscopy. The mineralogy and microtexture (grain size, sorting, roundness and sphericity) of the auger samples were determined using petrographic point count measurements obtained from grain-mount thin sections. NIH Image J (http://rsb.info.nih.gov/ij/) was applied to digital images of thin sections to document changes in particle size with depth. Results from TIR showed a general predominance of volcanic glass, along with plagioclase, olivine, and clinopyroxene. In addition, thin section and XRPD analyses showed a down core increase in the abundance of hydrated iron oxides (as in situ weathering products). Quantitative point count analyses confirmed the abundance of volcanic glass in samples, but also revealed olivine and pyroxene to be minor components, that decreased in abundance with depth. Furthermore, point count and XRD analyses showed a decrease in magnetite and ilmenite with depth, accompanied by an increase in Fe3+phases, including hematite and ferrihydrite. Image J particle analysis showed that the average grain size decreased down the depth profile. This decrease in average grain size and increase in hydrated iron oxides down hole suggests that the most favorable ISRU feedstock materials were sampled in the lower half-meter of the mine section sampled.

Marin, N.; Farmer, J. D.; Zacny, K.; Sellar, R. G.; Nunez, J.

2011-12-01

126

Mineral bioprocessing.  

National Technical Information Service (NTIS)

In the last 25 years, the introduction of biotechnological methods in hydrometallurgy has created new opportunities and challenges for the mineral processing industry. This was especially true for the production of metal values from mining wastes and low-...

A. E. Torma

1993-01-01

127

Secondary parkinsonism  

MedlinePLUS

Parkinsonism - secondary; Atypical Parkinson disease ... to be less responsive to medical therapy than Parkinson's disease. ... Unlike Parkinson disease, secondary parkinsonism may stabilize or even improve if the underlying cause is treated. Brain problems, such ...

128

Clay minerals from diallage in a warm and humid climate  

Microsoft Academic Search

In the course of chemical weathering, rockforming minerals release constituent ions changing into secondary minerals by alteration or recrystallization. Minerals formed in this way are primarily of colloidal nature, and are the most active portion in soils together with humus. The chemical weathering has dual meaning for soil fertility, that is, it provides soils with nutrients released and inorganic colloids

Shigenori Aomine; Nobufumi Miyauchi

1962-01-01

129

[Secondary osteoporosis or secondary contributors to bone loss in fracture. causes and pathophysiology of secondary osteoporosis].  

PubMed

Cases of osteoporosis that have a specific cause are defined as secondary osteoporosis. Secondary osteoporosis may be caused by various diseases and drugs, malnutrition, and other factors. Because secondary osteoporosis can be dramatically improved by treating the primary disease, it is extremely important to differentiate secondary osteoporosis at the time of diagnosis of primary osteoporosis. Because the pathophysiological condition that causes secondary osteoporosis varies by case, the degree to which low bone mineral density is involved in fracture risk also varies. Drug-induced secondary osteoporosis is caused by the side effects of treatment drugs used for the primary disease, and its management requires initiation of treatment with simultaneous prevention of the effects of drugs on bone. As with glucocorticoid-induced osteoporosis, there is an increasing awareness that simultaneous management of osteoporosis is necessary when performing estrogen or androgen deprivation therapy. PMID:23999359

Yamauchi, Mika; Sugimoto, Toshitsugu

2013-09-01

130

Mineral bioprocessing  

SciTech Connect

In the last 25 years, the introduction of biotechnological methods in hydrometallurgy has created new opportunities and challenges for the mineral processing industry. This was especially true for the production of metal values from mining wastes and low-and-complex-grade mineral resources, which were considered economically not amenable for processing by conventional extraction methods. Using bio-assisted heap, dump and in-situ leaching technologies, copper and uranium extractions gained their first industrial applications. The precious metal industries were the next to adopt the bio-preoxidation technique in the extraction of gold from refractory sulfide-bearing ores and concentrates. A variety of other bioleaching opportunities exist for nickel, cobalt, cadmium and zinc sulfide leaching. Recently developed bioremediation methods and biosorption technologies have shown a good potential for industrial applications to remove trace heavy metal and radionuclide concentrations from contaminated soils, and mining and processing effluents.

Torma, A.E.

1993-05-01

131

Mineral Commodities  

NSDL National Science Digital Library

This exercise introduces mineral commodities (elements). Students consider the elements aluminum, iron, copper, nickel, zinc, uranium, lead, gold, mercury and tin and match them with their definintions in a table. Then they use minable grade (minable weight percent) and normal crustal abundance (crustal weight percent) to calculate the concentration factor for several commodities to determine their economic minability. Students then graph their calculations and explain their trend.

Perkins, Dexter

132

Secondary atomization  

Microsoft Academic Search

When a drop is subjected to a surrounding dispersed phase that is moving at an initial relative velocity, aerodynamic forces\\u000a will cause it to deform and fragment. This is referred to as secondary atomization. In this paper, the abundant literature\\u000a on secondary atomization experimental methods, breakup morphology, breakup times, fragment size and velocity distributions,\\u000a and modeling efforts is reviewed and

D. R. Guildenbecher; C. López-Rivera; P. E. Sojka

2009-01-01

133

Mineral Sands Down Under  

NSDL National Science Digital Library

This resource describes what mineral sands are, and discusses the heavy, dark-colored minerals that they contain (rutile, ilmenite, zircon, monazite). A map shows locations of mineral sands deposits in Australia.

134

Minerals and Fossils  

NSDL National Science Digital Library

This site is dedicated to rock and mineral collecting. It contains information for worldwide mineral and fossil collectors with articles, mineral photos, videos, a search engine and free classified ads.

Mineraltown.com

135

[Secondary achalasia].  

PubMed

Achalasia is usually a primary disorder of esophageal motility, but has been described in association with other pathological processes, such as malignancy. A 79-year-old man with achalasia secondary to gastric adenocarcinoma is presented. The differential diagnosis of secondary achalasia includes infectious and infiltrative disease and neuropathy, but mainly malignant diseases. The clinical criteria found for achalasia secondary to malignancy included older age at diagnosis, brief duration of symptoms, and weight loss. While upper gastrointestinal x-rays and computerized tomographic scanning may be helpful, the most reliable diagnostic tool is esophago-gastro-duodenoscopy. This is a terminal disease with short life expectancy. Yet making the correct diagnosis can save the patient from futile treatment with muscle relaxants and endoscopic balloon dilatation, the accepted therapeutic measures in primary achalasia. PMID:8225085

Arnon, R; Fich, A; Bar-Ziv, J

1993-08-01

136

An integrated microtextural and chemical approach to zircon geochronology: refining the Archaean history of the Napier Complex, east Antarctica  

NASA Astrophysics Data System (ADS)

Integrated textural and chemical characterisation of zircon is used to refine the U-Pb geochronology of the Archaean, ultra-high temperature Napier Complex, east Antarctica. Scanning electron microscope characterisation of zircon and the rare earth element compositions of zircon, garnet and orthopyroxene are integrated to place zircon growth in an assemblage context, thereby providing tighter constraints on the timing of magmatic and metamorphic events. Data indicate that magmatism occurred in the central and northern Napier Complex at ca. 2,990 Ma. A regional, relatively low-pressure metamorphic event occurred at ca. 2,850-2,840 Ma. Mineral REE data from garnet-bearing orthogneiss indicate that ca. 2,490-2,485 Ma U-Pb zircon ages provide an absolute minimum age for the ultrahigh temperature (UHT) foliation preserved in this rock. Internal zircon zoning relationships and estimated zircon-garnet DREE values from paragneiss suggest that an absolute minimum age of ultra-high temperature metamorphism is ca. 2,510 Ma, but that it is more likely to be older than ca. 2,545 Ma. We suggest that the high proportion of published zircon U-Pb data with ages between ca. 2,490-2,450 Ma reflects late, post-peak zircon growth and does not date the timing of peak UHT metamorphism.

Kelly, Nigel M.; Harley, Simon L.

2005-03-01

137

Secondary seal  

Microsoft Academic Search

In floating tank roofs, due to various irregularities which are often found on the inside surfaces of tank walls, it is often difficult to maintain a seal with the tank wall. One of the problems encountered is that projections on the tank wall, such as, for example, welding beads, may, upon downward movement of the tank roof, engage the secondary

J. H. McBrien; G. T. Wright

1969-01-01

138

Mineral Scavenger Hunt  

NSDL National Science Digital Library

In this activity, learners participate in a scavenger hunt, searching for and recognizing minerals and products that contain minerals. They make note of their finds on a Mineral Scavenger Hunt checklist. Learners search for the materials in their classroom, at home, or even in stores. This resource includes discussion questions to encourage learner reflection about how minerals play a role in daily life.

History, National M.

2010-01-01

139

Mineral Spectroscopy Server  

NSDL National Science Digital Library

This server is primarily dedicated to providing information about color in minerals and access to data on mineral absorption in the visible, infrared, Raman and Mossbauer spectra. Both data coordinates and images of the spectra are available for selected minerals. Most data on the server were obtained in the Caltech mineral spectroscopy labs, but individuals throughout the world also contribute to this ever growing community resource. In addition to data files, the site provides an extensive list of references to papers on mineral optical spectroscopy. Citations are available sorted both by mineral name and by first authors of papers.

Rossman, George

140

Mathematical Model for the Mineralization of Bone  

NASA Technical Reports Server (NTRS)

A mathematical model is presented for the transport and precipitation of mineral in refilling osteons. One goal of this model was to explain calcification 'halos,' in which the bone near the haversian canal is more highly mineralized than the more peripheral lamellae, which have been mineralizing longer. It was assumed that the precipitation rate of mineral is proportional to the difference between the local concentration of calcium ions and an equilibrium concentration and that the transport of ions is by either diffusion or some other concentration gradient-dependent process. Transport of ions was assumed to be slowed by the accumulation of mineral in the matrix along the transport path. The model also mimics bone apposition, slowing of apposition during refilling, and mineralization lag time. It was found that simple diffusion cannot account for the transport of calcium ions into mineralizing bone, because the diffusion coefficient is two orders of magnitude too low. If a more rapid concentration gradient-driven means of transport exists, the model demonstrates that osteonal geometry and variable rate of refilling work together to produce calcification halos, as well as the primary and secondary calcification effect reported in the literature.

Martin, Bruce

1994-01-01

141

Mathematical Model for the Mineralization of Bone  

NASA Technical Reports Server (NTRS)

A mathematical model is presented for the transport and precipitation of mineral in refilling osteons. One goal of this model was to explain calcification 'halos,' in which the bone near the haversian canal is more highly mineralized than the more peripheral lamellae, which have been mineralizing longer. It was assumed that the precipitation rate of mineral is proportional to the difference between the local concentration of calcium ions and an equilibrium concentration and that the transport of ions is by either diffusion or some other concentration gradient-dependent process. Transport of ions was assumed to be slowed by the accumulation of mineral in the matrix along the transport path. ne model also mimics bone apposition, slowing of apposition during refilling, and mineralization lag time. It was found that simple diffusion cannot account for the transport of calcium ions into mineralizing bone, because the diffusion coefficient is two orders of magnitude too low. If a more rapid concentration gradient-driven means of transport exists, the model demonstrates that osteonal geometry and variable rate of refilling work together to produce calcification halos, as well as the primary and secondary calcification effect reported in the literature.

Martin, Bruce

1994-01-01

142

Mineral Resources: Mineral Volume, Value and Revenue.  

National Technical Information Service (NTIS)

The Department of the Interior (Interior) administers minerals found in over 700 million acres of federal lands, 57 million acres on Indian lands, and 1.8 billion acres below offshore waters. Operators who lease these lands and extract these minerals pay ...

2012-01-01

143

Heavy Mineral Processing at Richards Bay Minerals  

Microsoft Academic Search

Located on the eastern shores of South Africa, 180 km north of Durban, Richards Bay Minerals (RBM) produces approximately 2.0 million metric tonnes of product annually making RBM a leading producer of titania slag, high purity pig iron, rutile and zircon. Heavy minerals are extracted from the nearby dunes by dredging and concentration on a floating gravity separation plant, followed

G. E. Williams; J. D. Steenkamp; Richards Bay Minerals; Richards Bay

144

Mineral Commodity Summaries, 2008.  

National Technical Information Service (NTIS)

Each chapter of the 2008 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry str...

2008-01-01

145

Ohio Mineral Resources Management  

NSDL National Science Digital Library

Provides information about Mineral Resources in Ohio and management. Mine safety, oil and gas, coal mining, industrial minerals, and abandoned mined lands are related subheadings for the site. Good for finding history, factual reports, programs, regulations and policies.

2008-10-06

146

Minerals in Sports  

NSDL National Science Digital Library

This series of articles describes the uses of mineral products in sports and sporting equipment. The site also explores minerals use in safety applications in the workplace. A series of reading material sheets are included in PDF format.

2011-07-06

147

Minerals Yearbook: Cuba, 2006.  

National Technical Information Service (NTIS)

Nickel was the most important mineral commodity to the Cuban economy followed by cobalt, which was produced as a byproduct of nickel mining. Other minerals produced in the country included cement, clays, crushed stone, feldspar, salt, and silica sand. Cub...

O. Bermudez-Lugo

2008-01-01

148

Mineral Properties Sheets  

NSDL National Science Digital Library

These sheets are designed to give students a framework for making observations of minerals in hand specimen and (for selected minerals) in thin section. I place most of the emphasis on the distinguishing properties, rather than requiring an exhaustive list. Students use hand specimen observation, thin section observation (for selected minerals) and references to complete the forms.

Hirsch, Dave

149

Rocks and Minerals  

NSDL National Science Digital Library

This unit provides younger students with an introduction to rocks and minerals. Topics include the definition of a mineral, the physical properties of minerals and how they are measured, and a discussion of quartz, the most basic silicate mineral and one of the most abundant minerals in the Earth's crust. The discussion on rocks includes the rock cycle, the three rock types (igneous, sedimentary, metamorphic), and how they are formed. There is also a vocabulary list and downloadable, printable worksheets for each major topic.

Medina, Philip

2010-09-08

150

Iron-titanium oxide minerals and associated alteration phases in some uranium-bearing sandstones  

Microsoft Academic Search

Detrital iron-titanium (Fe--Ti) oxide minerals of the ulvospinel-magnetite (titanomagnetite) and ilmenite-hematite (titanohematite) solid solution series are common in uranium-bearing sandstones. Alteration of Fe--Ti oxide minerals in oxidizing environments formed secondary products (primarily hematite) that are distinct from those produced under reducing conditions (iron disulfide minerals). Oxidation of sulfidized Fe--Ti oxide minerals, by the processes that formed uranium rolls, produced ferric

R. L. Reynolds; M. B. Goldhaber

1978-01-01

151

Ion beam microtexturing of surfaces  

NASA Technical Reports Server (NTRS)

Some recent work in surface microtecturing by ion beam sputtering is described. The texturing is accomplished by deposition of an impurity onto a substrate while simultaneously bombarding it with an ion beam. A summary of the theory regarding surface diffusion of impurities and the initiation of cone formation is provided. A detailed experimental study of the time-development of individual sputter cones is described. A quasi-liquid coating was observed that apparently reduces the sputter rate of the body of a cone compared to the bulk material. Experimental measurements of surface diffusion activation energies are presented for a variety of substrate-seed combinations and range from about 0.3 eV to 1.2 eV. Observations of apparent crystal structure in sputter cones are discussed. Measurements of the critical temperature for cone formation are also given along with a correlation of critical temperature with substrate sputter rate.

Robinson, R. S.

1981-01-01

152

Distinctive Accessory Minerals, Textures and Crystal Habits in Biofilm Associated Gypsum Deposits  

NASA Astrophysics Data System (ADS)

Gypsum-depositing environments near Guerrero Negro, Baja California Sur, Mexico were investigated in order to differentiate the influence of microbial activity versus nonbiological processes upon sedimentary fabrics and minerals. Field sites were located in sabkhas (mudflats and anchialine pools) and in seawater concentration ponds in the salt production facility operated by Exportadora de Sal, S. A. Gypsum (CaSO4.2H2O) was classified according to sedimentary environment (e.g., mudflats, anchialine pools, saltern ponds, surface and subsurface sediments), sedimentary texture, mineral composition, crystal habit, brine composition and other geochemical and biological factors. Gypsum types that develop in the absence of biofilms include water column precipitates (pelagic grains) and subsedimentary crystalline discs that form from phreatic brine ripening. Subsedimentary gypsum forming in sabkha environments had a sinuous axial microtexture and poikilitically enclosed detrital particles whereas water column precipitates exhibited euhedral prismatic habits and extensive penetrative twinning. Gypsum that was influenced by biofilms included cumulate crusts and gypsooids / gypsolite developing in anchialine pools and in saltern concentration ponds. Gypsum precipitating within subaqueous benthic microbial mats, or biofilm/sediment surfaces offered compelling evidence of biofilm influence on crystal textures and habits. Biofilm effects include irregular high relief surface textures, accessory minerals (elemental sulfur, Ca-carbonate, Sr/Ca-sulfate, Mg-oxide and Mg- sulfate) and distinctive crystal habits. Elemental sulfur, Ca-carbonate, and Sr/Ca-sulfate are known byproducts of bacterially mediated sulfate reduction (BSR). Populations of gypsum crystals within biofilms exhibited euhedral to lensoidal morphologies with unique equant and distorted prismatic forms. These forms had been shown to arise from form- and face-specific inhibition by bioorganic functional groups (Cody, 1991; Cody and Cody 1991). Biofilms therefore may play an active role in influencing brine chemistry, inducing crystallization and modifying crystal habits, evidence of which is preserved in grain morphologies.

Vogel, M.; Des Marais, D.; Jahnke, L.; Parenteau, M.

2008-12-01

153

Chemical Changes of Minerals Trapped in the Lichen Trapelia involuta: Implication for Lichen Effect on Mobility of Uranium and Toxic Metals  

Microsoft Academic Search

To elucidate development of minerals trapped in a lichen, we examined the lichen Trapelia involuta growing directly on secondary uranyl minerals and U-enriched Fe oxide and hydroxide minerals. Sericite and other minerals in the underlying rock are trapped in the lichen T. involuta during its biological growth and chemically changed by lichen activities. The presence of chemically changed sericite accompanied

Takeshi KASAMA; Takashi MURAKAMI; Toshihiko OHNUKI; O. William PURVIS

154

Virtual Mineral Exhibit  

NSDL National Science Digital Library

This is the New York State Museum's virtual exhibit of minerals, which are classified in cases referenced by topic, location, and sponsor. The minerals are presented as a thumbnail image with specifications. Clicking on the thumbnail gives one a large zoomable image. Other exhibitions at the museum site include Splendor in Stone: Photomicrographs of Stone, which is a collection of photomicrographs of thin sections of rocks. A 3D (three-dimensional) index of minerals is also available.

155

Weathering of Minerals  

NSDL National Science Digital Library

Students determine the % change in mass of mineral samples that have been placed in a rock tumbler. They graph the relationship between the hardness of the mineral and the % change in mass. They then consider why some of the mineral samples do not conform the the relationship they graphed. They investigate the physical properties of the outliers and consider how the physical properties contributed to the rate of weathering, and what kind of weathering occured in the rock tumbler.

Van Norden, Wendy

156

Minerals Under the Microscope  

NSDL National Science Digital Library

This website provides an easy-to-understand introduction to the basics of optical mineralogy. Topics include the polarized light microscope, mineral shape and cleavage, relief, color and pleochroism, interference colors, extinction angles, twinning, opacity, vibration directions and mineral identification. The site features short, clear descriptions accompanied by photographs and drawings. This website would be useful as a concise introduction to the use of a petrographic microscope in identifying minerals.

Browning, Paul; Gladstone, Charlotte

2011-03-02

157

Mineral Classification Exercise  

NSDL National Science Digital Library

This exercise is designed to help students think about the properties of minerals that are most useful for mineral classification and identification. Students are given a set of minerals and asked to come up with a hierarchical classification scheme (a "key") that can be used to identify different mineral species. They compare their results with the products of other groups. They test the various schemes by applying them to unknown samples. While doing this exercise, the students develop observational and interpretational skill. They also begin to think about the nature of classification systems.

Perkins, Dexter

158

USGS: Mineral Resources Program  

NSDL National Science Digital Library

"The Mineral Resources Program funds science to provide and communicate current, impartial information on the occurrence, quality, quantity, and availability of mineral resources." This website divides the mineral resource information, project descriptions, and products for the United States into four main regional categories: Eastern, Central, Western, and Alaska. Researchers can discover new grant opportunities and can obtain access to the National Geochemical Survey's database. Students and educators can find statistics and information on how the United State's supply-and-demand for minerals and materials affects the economy, security, and environment.

159

Biological impact on mineral dissolution: Application of the lichen model to understanding mineral weathering in the rhizosphere  

PubMed Central

Microorganisms modify rates and mechanisms of chemical and physical weathering and clay growth, thus playing fundamental roles in soil and sediment formation. Because processes in soils are inherently complex and difficult to study, we employ a model based on the lichen–mineral system to identify the fundamental interactions. Fixed carbon released by the photosynthetic symbiont stimulates growth of fungi and other microorganisms. These microorganisms directly or indirectly induce mineral disaggregation, hydration, dissolution, and secondary mineral formation. Model polysaccharides were used to investigate direct mediation of mineral surface reactions by extracellular polymers. Polysaccharides can suppress or enhance rates of chemical weathering by up to three orders of magnitude, depending on the pH, mineral surface structure and composition, and organic functional groups. Mg, Mn, Fe, Al, and Si are redistributed into clays that strongly adsorb ions. Microbes contribute to dissolution of insoluble secondary phosphates, possibly via release of organic acids. These reactions significantly impact soil fertility. Below fungi–mineral interfaces, mineral surfaces are exposed to dissolved metabolic byproducts. Through this indirect process, microorganisms can accelerate mineral dissolution, leading to enhanced porosity and permeability and colonization by microbial communities.

Banfield, Jillian F.; Barker, William W.; Welch, Susan A.; Taunton, Anne

1999-01-01

160

Constraining kinetic rates of mineral reactions using reactive transport models  

NASA Astrophysics Data System (ADS)

We use a reactive transport model to better understand results of experiments to obtain kinetic rates of mineral reactions in closed systems. Closed system experiments pose special challenges in that secondary minerals may form that modify the fluid composition evolution and may grow on the dissolving minerals thus armoring the surface. Even so, such closed system experiments provide critical data for what minerals would actually form in field applications and how coupled dissolution and precipitation mineral reactions are strongly linked. Comparing to experimental observations can test the reactive transport model, and the experimental observations can be better understood by comparing the results to the modeling. We apply a 0D end member of the model to understand the dissolution of single crystals of forsterite in a variety of settings (low pH, high pH, or NaHCO3 initial fluids, at 100 C and 1 bar, or 200 C and 150 bar). Depending on the initial conditions, we observe the precipitation of talc, brucite, amorphous silica, chrysotile, or magnesite, in various combinations. We compare simulation results to fluid compositions and the presence of secondary minerals experimentally sampled at various times. Insight from the simulations helped create an inverse model to extract the rates of forsterite dissolution and to create a simple forward model useful for exploring the influence of system size, secondary mineral surface areas, etc. Our reactive transport model allows secondary minerals to armor the forsterite surface, which can strongly decrease the dissolution rate as the system evolves. Tuning our model with experimentally derived rates and assuring relevant processes are included so as to reproduce experimental observations is necessary before upscaling to heterogeneous field conditions. The reactive transport model will be used for field-scale sequestration simulations and coupled with a geomechanical model that includes the influence of deformation.

Bolton, E. W.; Wang, Z.; Ague, J.; Bercovici, D.; Cai, Z.; Karato, S.; Oristaglio, M. L.; Qiu, L.

2012-12-01

161

MINER{nu}A Test Beam Commissioning  

SciTech Connect

MINER{nu}A Main INjector ExpeRiment {nu}-A is a high-statistic neutrino scattering experiment that will ran in the NuMI Beam Hall at Fermilab. To calibrate the energy response of the MINER{nu}A detector, a beamline is being designed for the MINER{nu}A Test Beam Detector (TBD). The TBD is a replica of the full MINER{nu}A detector at small scale for calibration studies of the main detector. The beamline design consists of the following parts: a copper target, used to generate tertiaries from an incoming secondary beam; a steel collimator for tertiaries, which also serves as a dump for the incoming beam; a time of fight system (scintillator planes); four wire chambers, for angle measurements and tracking; and two dipole magnets, used as an spectrometer. During last October, the first commissioning run of the MINER{nu}A Test Beam took place in the Meson Test Beam Facility at Fermilab. We commissioned the target and collimator of the new tertiary beamline.

Higuera, A.; Castorena, J.; Urrutia, Z.; Felix, J. [Universidad de Guanajuato, Division De Ciencias e Ingenerias, Leon Gto., Mex (Mexico); Zavala, G. [Universidad de Guanajuato, DCEA, Guanajuato Gto., Mex (Mexico)

2009-12-17

162

Minerals Yearbook, 1990: Mississippi.  

National Technical Information Service (NTIS)

The value of Mississippi's nonfuel mineral production in 1990 totaled $112 million, according to data supplied to the U.S. Bureau of Mines by the State's mineral producers. The 1990 value exceeded that reported by industry in 1989 by $4.7 million and exce...

D. H. White S. C. Knox M. B. E. Bograd

1992-01-01

163

Minerals Yearbook, 1990: Idaho.  

National Technical Information Service (NTIS)

The 1990 Annual Report is on the Mineral Industry of Idaho. Idaho ranked 26th nationally for total mineral production value compared with 28th in 1989. The State was first in the Nation in antimony and garnet production; second in silver and vandaium prod...

R. J. Minarik V. S. Gillerman

1992-01-01

164

Minerals Yearbook 1989: Boron  

Microsoft Academic Search

U.S. production and sales of boron minerals and chemicals decreased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to distributors, textile-grade glass fibers, and borosilicate glasses. California was the only domestic source of boron minerals. The United States continued to provide essentially all of its own supply while maintaining a strong position

Lyday

1990-01-01

165

The Miner's Canary  

ERIC Educational Resources Information Center

Miners used canaries as early warning signals: when a canary gasped for breath, the miners knew there was a problem with the atmosphere in the mine. The experience of people of color in higher education can be used similarly as a diagnostic tool.

Guinier, Lani

2005-01-01

166

Mineral storage problems overcome  

SciTech Connect

Reinforced Earth, the method of using precast concrete panels to face a compacted earth embankment for mineral storage and handling, is described. The construction and operation of this type of mineral storage facility are discussed. These facilities are simple to build, durable, and cost-effective in operation.

Not Available

1984-08-01

167

What is a Mineral?  

NSDL National Science Digital Library

This website, from the University Corporation for Atmospheric Research (UCAR), gives a description of minerals and the growth of crystals. The site offers various links with examples of different compositions and classifications of common minerals. The site provides three different levels of explanation--beginner, intermediate, and advanced.

2008-08-04

168

Minerals Yearbook, 1992: Oklahoma.  

National Technical Information Service (NTIS)

The value of Oklahoma nonfuel mineral production was nearly $252.6 million in 1992, a decrease of $22.9 million from that reported to the U.S. Bureau of Mines by State mineral producers in 1991. The value of the top three commodities produced, crushed sto...

J. E. Zelten R. H. Arndt

1994-01-01

169

Digging into Minnesota Minerals.  

ERIC Educational Resources Information Center

This publication presents students with facts about geology and several learning activities. Topics covered include rocks and minerals, volcanoes and earthquakes, fossils, exploration geology, mining in Minnesota, environmental issues related to mining, mineral uses, mining history, and the geology of Minnesota's state parks. A geologic timetable…

Minnesota State Dept. of Natural Resources, St. Paul.

170

Minerals, Crystals and Gems  

NSDL National Science Digital Library

This module introduces students to minerals, crystals, and gems by using pictures and discussions of some of the extraordinary specimens residing in the collections of the Smithsonian Institution. It includes three lessons in which they draw pictures of specimens, grow their own crystals of magnesium sulfate, and perform a scavenger hunt in which they look for minerals in commonly used objects and products.

171

Mineral Image Index  

NSDL National Science Digital Library

This image gallery provides pictures of thousands of mineral specimens, arranged alphabetically. For each specimen, a thumbnail and a larger image are provided. Other information includes a brief description of the specimen being shown, scale bar (when available), locality data, and a link to additional information on the mineral.

172

Rocks and Minerals  

NSDL National Science Digital Library

This description of rocks and minerals includes representatives of all three major groups: igneous, sedimentary, and metamorphic. Users can access introductory information about the three major rock types and the minerals that form them. A simple rock classification chart is included, with embedded links to a glossary and more detailed material for advanced learners.

173

Mineral Resources in Afghanistan.  

National Technical Information Service (NTIS)

Despite Afghanistan's wide variety of mineral resources and long history of small-scale mining of gems, gold, copper, and coal, it was not until the 1950's that the country's mineral resources were subject to systematic exploration. The report documents t...

1992-01-01

174

Minerals Yearbook 1989: Lithium  

Microsoft Academic Search

The United States led the world in lithium mineral and compound production and consumption. Estimated consumption increased slightly, and world production also grew. Sales increased for domestic producers, who announced price increases for the third consecutive year. Because lithium is electrochemically reactive and has other unique properties, there are many commercial lithium products. Producers sold lithium as mineral concentrate, brine,

Ober

1989-01-01

175

Mineral Gallery - The Physical Properties of Minerals  

NSDL National Science Digital Library

Hosted by Amethyst Galleries, Inc., this site introduces users to the physical characteristics of minerals; these includes: color, luster, transparency, cleavage, hardness and many more. A good introduction is what the sites provides, it would be great for any beginning level course involving the topic.

2008-10-07

176

USGS: Energy & Minerals  

NSDL National Science Digital Library

The Energy and Minerals Mission Area of the United States Geological Survey (USGS) "conducts research and assessments on the location, quantity, and quality of material and energy resources, including the economic and environmental effects of resource extraction and use." Visitors to the site can click on thematic sections such as Energy Resources and Mineral Resources. Each of these areas contains information about each program, along with fact sheets, databases, and detailed geospatial maps. The Program News area contains links to documents such as "Understanding the Global Distribution of Nonfuel Mineral Resources" and a host of summary documents on mineral commodities. Finally, the site is rounded out by the Mineral Resources Products area. Here, visitors can look into hundreds of statistical reports, bulletins, and data sets intended for scientists, journalists, and members of the general public.

2013-06-20

177

Minerals yearbook, 1993. Volume 1. Metals and minerals. Annual report  

SciTech Connect

This edition of the Mineral Yearbook discusses the performance of the worlwide minerals and materials industry during 1993 and provides background information to assist in interpreting that performance. Volume 1, Metals and Minerals, contains chapters on virtually all metallic and industrial mineral commodities important to the U.S. economy. A chapter on survey methods with a statistical summary of nonfuel minerals, and a chapters on trends in mining and quarrying in the metals and industrial mineral industries are also included.

NONE

1993-12-31

178

Biological Control on Mineral Transformation in Soils ?  

NASA Astrophysics Data System (ADS)

Weathering of primary minerals is commonly linked to biological processes through the production of carbonic and organic acids. Plants can also play a role in weathering by removing soluble constituents and enhancing diffusion gradients within the soil. Here we investigate the synthesis of secondary minerals and the role of plants in removing elements that act as building blocks for these minerals. In order to minimize losses from leaching, we have sampled a chronosequence of soils forming on lava flows on Hawaii Island that receive about 200 mm of rain annually and have never been subjected to high levels of rainfall. The P concentration in the soils drops from almost 3000 mg/kg on a 1.5 ky lava flow to around 1000 mg/kg on a 350 ky lava flow. This loss of P can only be ascribed to P-uptake by plants with subsequent removal through the loss of above ground biomass through fire and/or wind removal. Over the same time frame the amount of plagioclase in the soils drops from around 22% of the <2 mm soil fraction on the youngest lava flow to virtually 0% on the 350 ky flow, suggesting a substantial release of Si. Elevated silicon in arid, basaltic soil environments often leads to formation of smectite, a feature not observed along the chronosequence. In fact, plagioclase is replaced by the kaolin mineral halloysite with allophane as an apparent precursor. Kaolin minerals are associated with moderate to intense leaching environments rather than the mild leaching conditions that influence these soils. We selected an intermediate age soil profile (170 ky lava flow) to conduct an in-depth investigation of the soil mineral composition. We detected a strong dominance of halloysite, the presence of gibbsite, but no smectite. Secondary halloysite formation is preferred over smectite formation when Si activities are relatively low, and the pH is acidic rather than alkaline. Although this mineral assemblage seems to imply formation under a wetter climatic regime, the oxygen isotopic composition of the halloysite suggests formation under soil environmental conditions similar to the present. The Si concentration in grass and tree leaves in the vicinity of the soil contain between 3 and 8% Si. Loss of these leaves to the nearby ocean (either as dried or burned residue) could be responsible for considerable Si removal in a manner similar to the P-removal. The resulting Si-deficient soil-water favors the formation of halloysite over smectite as is demonstrated by construction of mineral stability diagrams using the soil-water data from the soils along the chronosequence.

Ziegler, K.; Hsieh, J. C.; Chadwick, O. A.; Kelly, E. F.

2001-12-01

179

Mineral Industries of Western Europe.  

National Technical Information Service (NTIS)

This report presents a summary of the mineral industries of the nine members of the European Community, the seven members of the European Free Trade association, and three additional countries. Base maps show mineral deposit and mineral processing plant l...

W. F. Keyes R. V. Sondermayer J. B. Huvos

1977-01-01

180

American Strategic Minerals  

NASA Astrophysics Data System (ADS)

American Strategic Minerals is a collection of six papers that were presented in December 1982 at a conference organized by the Center for the Study of Marine Policy at the University of Delaware. According to editor Gerard J. Mangone, director of the center, the papers were commissioned “to investigate not only the objective resource situation, but also past United States policy on strategic minerals and future options open to Washington.” The authors and their chapter titles are John C. Kraft, University of Delaware: “Strategic minerals and world stability” V. Anthony Cammarota, Jr., U.S. Bureau of Mines: “America's dependence on strategic minerals” John D. Morgan, U.S. Bureau of Mines: “Future demands of the United States for strategic minerals” J. Robert Moore, University of Texas: “Alternative sources of strategic minerals from the seabed” Allan I. Mendelowitz and John E. Watson, U.S. General Accounting Office: “U.S. mining investments in developing countries” and James W. Curlin, Nautilus Press: “The political dimensions of strategic minerals.”

DeYoung, John H., Jr.; Chidester, Alfred H.

181

Minerals Management Service: Strategic plan  

SciTech Connect

This plan addresses the management of the mineral resources on the Outer Continental Shelf in an environmentally sound and safe manner and the timely collection, verification, and distribution of mineral revenues from Federal and Indian lands. The Minerals Management Service (MMS) manages the Nation`s natural gas, oil and other mineral resources on the Outer Continental Shelf (OCS), and collects, accounts for, and disburses revenues from offshore federal mineral leases and from onshore mineral leases on Federal and Indian lands.

NONE

1997-09-30

182

Primary and Secondary Sources  

NSDL National Science Digital Library

Use these links to learn more about primary and secondary sources. 1. Explore the links below to learn about primary and secondary sources. When you have finished, you should be able to: Tell the difference between primary and secondary sources. Give at least three examples of primary sources and three examples of secondary sources. Explain why primary sources are important in research. Examples of Primary Sources Examples of Primary and Secondary Sources on the Same Topic Genres/Formats of Primary Sources 2. ...

Bates, Albion M.

2010-01-23

183

43 CFR 19.8 - Prospecting, mineral locations, mineral patents, and mineral leasing within National Forest...  

Code of Federal Regulations, 2013 CFR

...patents, and mineral leasing within National Forest Wilderness. 19.8 Section 19.8...patents, and mineral leasing within National Forest Wilderness. Regulations issued under...and mineral leasing within National Forest Wilderness are contained in parts...

2013-10-01

184

Multivitamin/Mineral Supplements  

MedlinePLUS

... we know so little about whether MVMs have health benefits is that studies often use different products, making ... vitamins, minerals, dietary fiber and other substances that benefit health. Dietary supplements might help in some situations to ...

185

Mineral oil overdose  

MedlinePLUS

... Diaper rash medications Eye care products Hemorrhoid medications Laxatives Note: This list may not include every product ... Symptoms are due to mineral oil's laxative action and may ... pain Dehydration (from severe diarrhea) Diarrhea Nausea Vomiting

186

Characterization Lithium Mineralized Pegmatite.  

National Technical Information Service (NTIS)

Lithium economic importance has increased in the last years. In Brazil its reserves, generally pegmatites bodies, are found in Itinga-Aracuai-MG. This study of characterization belongs to a global plan of lithium mineralized bodies research of 'Arqueana d...

E. F. S. Pereira O. Luz Ferreira R. Z. L. Cancado J. Mauricio Neto

1986-01-01

187

Calcium Carbonate Mineralization.  

National Technical Information Service (NTIS)

The objectives of the present study were to determine the mechanisms of ion transport across mineralizing epithelia of barnacles, in particular to quantify the effects of altered protein structure on crystal form and arrangement and the effects of the mol...

K. M. Wilbur A. LeFurgey

1995-01-01

188

Mineral Commodity Summaries 1983.  

National Technical Information Service (NTIS)

This report is the earliest Government publication to furnish estimates covering 1982 nonfuel mineral industry data. Most of the estimates are based on 9 months data. These data sheets contain information on the domestic industry structure, Government pro...

1983-01-01

189

Minerals Yearbook, 1988: Thorium.  

National Technical Information Service (NTIS)

Mine production of monazite, the principal source of thorium, decreased slightly in 1988. Associated Minerals (USA) Inc. was the only domestic monazite producer. Monazite produced in the United States was exported, and the thorium products used domestical...

J. B. Hedrick

1988-01-01

190

Mineral Wool Insulation Binders  

Microsoft Academic Search

\\u000a Mineral wool is considered the best known insulation type among the wide variety of insulation materials. There are three\\u000a types of mineral wool, and these consist of glass, stone (rock), and slag wool. The overall manufacturing processes, along\\u000a with features such as specifications and characteristics for each of these types, as well as the role of the binder within\\u000a the

Stefan Kowatsch

2010-01-01

191

Mineral prospecting manual  

SciTech Connect

This book: provides the mineral prospector with a series of essential guidelines for the work he must do and the precautions he will have to take; shows how successful mineral prospecting is dependent on the critical examination of technical, economic and financial data examined during each phase of the operation; and provides information on physical preparations for prospecting, hammer prospecting, prospecting in coastal formations, drilling techniques and equipment, sampling procedures, and current research methods (e.g.: remote sensing and geochemistry).

Chaussier, J.B.; Morer, J.

1986-01-01

192

Vitamins, Minerals, and Mood  

Microsoft Academic Search

In this article, the authors explore the breadth and depth of published research linking dietary vitamins and minerals (micronutrients) to mood. Since the 1920s, there have been many studies on individual vitamins (especially B vitamins and Vitamins C, D, and E), minerals (calcium, chromium, iron, magnesium, zinc, and selenium), and vitamin-like compounds (choline). Recent investigations with multi-ingredient formulas are especially

Bonnie J. Kaplan; Susan G. Crawford; Catherine J. Field; J. Steven A. Simpson

2007-01-01

193

Ice is a Mineral  

NSDL National Science Digital Library

This is a lesson about the characteristics of ice as a mineral and how it compares to other minerals with respect to hardness. Learners will observe ice crystals, develop a hardness scale and position ice on it. Learners will also practice working collaboratively in a team. Activities include small group miming, speaking, drawing, and/or writing. This is lesson 3 of 12 in the unit, Exploring Ice in the Solar System.

194

Minerals: the resource gap  

SciTech Connect

US imports of important non-fuel minerals may have contributed to a false sense of security that could have serious economic and defense consequences. Imports account for over 90 percent of the chromite, manganese ore, and cobalt, and 90 percent of the platinum group metals. The primary sources for many of these minerals are the Soviet Union and Africa, a price and supply vulnerability which rivals Middle East oil and of which the American public is unaware. The Soviet shift to a net minerals importer will intensify competition for minerals and could lead to confrontation. The decline in US mineral production is blamed on escalating costs, largely from regulations, that prevent plant and equipment modernization and land withdrawal policies. A strategic stockpile planned for over 90 materials was established in 1939 for defense purposes, but eratic goals and planning as well as economic changes have kept the plan from being implemented. The first steps of an appropriate policy would promote domestic minerals production and open up Federal lands for exploration and development. (DCK)

Velocci, T.

1980-10-01

195

Minerals yearbook, 1993. Volume 1. Metals and minerals. Annual report  

SciTech Connect

This edition of the Minerals Yearbook discusses the performance of the worldwide minerals and materials industry during 1993 and provides background information to assist in interpreting that performance. It contains chapters on virtually all metallic and industrial mineral commodities important to the U.S. economy. A chapter on survey methods with a statistical summary of nonfuel minerals, and a chapter on trends in mining and quarrying in the metals and industrial mineral industries are also included.

NONE

1993-12-31

196

Minerals yearbook, 1994. Volume 1. Metals and minerals. Annual report  

SciTech Connect

The edition of the Minerals Yearbook discusses the performance of the worldwide minerals and materials industry during 1994 and provides background information to assist in interpreting that performance. The volume I, Metals and Minerals, contains chapters on virtually all metallic and industrial mineral commodities important to the U.S. economy. The volume also contains chapters on Survey Methods, a Statistical Summary of Nonfuel Minerals, and Trends in Mining and Quarrying.

NONE

1994-12-31

197

Mineral sources and transport pathways for arsenic release in a coastal watershed, USA  

USGS Publications Warehouse

Metasedimentary bedrock of coastal Maine contains a diverse suite of As-bearing minerals that act as significant sources of elements found in ground and surface waters in the region. Arsenic sources in the Penobscot Formation include, in order of decreasing As content by weight: lo??llingite and realgar (c. 70%), arsenopyrite, cobaltite, glaucodot, and gersdorffite (in the range of 34-45%), arsenian pyrite ( glaucodot, arsenopyrite-cobaltian > arsenopyrite, cobaltite, gersdorffite, fine-grained pyrite, Ni-pyrite > coarse-grained pyrite. Reactions illustrate that oxidation of Fe-As disulphide group and As-sulphide minerals is the primary release process for As. Liberation of As by carbonation of realgar and orpiment in contact with high-pH groundwaters may contribute locally to elevated contents of As in groundwater, especially where As is decoupled from Fe. Released metals are sequestered in secondary minerals by sorption or by incorporation in crystal structures. Secondary minerals acting as intermediate As reservoirs include claudetite (c. 75%), orpiment (61%), scorodite (c. 450%), secondary arsenopyrite (c. 469/6), goethite (<4490 ppm), natrojarosite (<42 ppm), rosenite, melanterite, ferrihydrite, and Mn-hydroxide coatings. Some soils also contain Fe-Co-Ni-arsenate, Ca-arsenate, and carbonate minerals. Reductive dissolution of Fe-oxide minerals may govern the ultimate release of iron and arsenic - especially As(V) - to groundwater; however, dissolution of claudetite (arsenic trioxide) may directly contribute As(III). Processes thought to explain the release of As from minerals in bedrock include oxidation of arsenian pyrite or arsenopyrite, or carbonation of As-sulphides, and most models based on these generally rely on discrete minerals or on a fairly limited series of minerals. In contrast, in the Penobscot Formation and other metasedimentary rocks of coastal Maine, oxidation of As-bearing Fe-cobalt-nickel-sulphide minerals, dissolution (by reduction) of As-bearing secondary As and Fe hydroxide and sulphate minerals, carbonation and/or oxidation of As-sulphide minerals, and desorption of As from Fe-hydroxide mineral surfaces are all thought to be involved. All of these processes contribute to the occurrence of As in groundwaters in coastal Maine, as a result of variability in composition and in stability of the As source minerals. Arsenic contents of soils and groundwater thus reflect the predominant influence and integration of a spectrum of primary mineral reservoirs (instead of single or unique mineral reservoirs). Cycling of As through metasedimentary bedrock aquifers may therefore depend on consecutive stages of carbonation, oxidation and reductive dissolution of primary and secondary As host minerals. ?? 2008 AAG/ Geological Society of London.

Foley, N. K.; Ayuso, R. A.

2008-01-01

198

ASSESSMENT OF ENVIRONMENTAL IMPACT OF THE MINERAL MINING INDUSTRY  

EPA Science Inventory

This report presents a multimedia (air, liquid and solid wastes) environmental assessment of the domestic mineral mining industry. The primary objective of the study was to identify the major pollution problems associated with the industry. A secondary objective was to define res...

199

Mineral Detector for Igneous Rocks  

Microsoft Academic Search

We present a Raman spectral analysis tool that uses machine learning algorithms to classify pure minerals in igneous rocks. Experiments show greater than 90% accuracy classifying a test set of pure minerals against a database of similar reference minerals using an artificial neural network. Efforts are currently underway to improve this tool for use as a mineral detector in rock

S. T. Ishikawa; S. D. Hart; V. C. Gulick

2010-01-01

200

The Mineral and Gemstone Kingdom  

NSDL National Science Digital Library

The "Mineral and Gemstone Kingdom" allows one to sort and search for minerals and gemstones by alphabetical, chemical group, color, streak, hardness, crystal group, elemental affiliations, and dana classification. Includes image galleries of rocks, minerals and gemstones: pictures accompanied with physical descriptions of the rock or mineral. Also includes a glossary of terms.

2008-08-21

201

Occurrence of secondary magnetite within biodegraded oil  

SciTech Connect

Samples of solid bitumen from the Thornton Quarry (Illinois) and the Cynthia Quarry (Mississippi) were found to be strongly magnetic and to have rock magnetic properties suggesting that the magnetizable grains present are magnetite. Studies of magnetic isolates revealed that magnetite is present primarily as spherical crystal aggregates that appear identical to magnetite spherules isolated from remagnetized Paleozoic carbonate units from other localities. Organic geochemical analyses of the solid bitumen suggest an origin by microbial attack on what once was liquid crude oil. The occurrence of secondary magnetite as inclusions within solid bitumen suggests a relationship between crude oil biodegradation and development of that mineral in their samples. The authors infer that secondary magnetite in other geologic environments may be related to the presence of hydrocarbons. The discovery of a natural association of secondary magnetite and hydrocarbons has important implications for paleomagnetism and for petroleum exploration.

McCabe, C.; Sassen, R.; Saffer, B.

1987-01-01

202

Occurrence of secondary magnetite within biodegraded oil  

NASA Astrophysics Data System (ADS)

Samples of solid bitumen from the Thornton Quarry (Illinois) and the Cynthia Quarry (Mississippi) were found to be strongly magnetic and to have rock magnetic properties suggesting that the magnetizable grains present are magnetite. Studies of magnetic isolates revealed that magnetite is present primarily as spherical crystal aggregates that appear identical to magnetite spherules isolated from re-magnetized Paleozoic carbonate units from other localities. Organic geochemical analyses of the solid bitumen suggest an origin by microbial attack on what once was liquid crude oil. The occurrence of secondary magnetite as inclusions within solid bitumen suggests a relationship between crude oil biodegradation and development of that mineral in our samples. We infer that secondary magnetite in other geologic environments may be related to the presence of hydrocarbons. The discovery of a natural association of secondary magnetite and hydrocarbons has important implications for paleomagnetism and for petroleum exploration.

McCabe, Chad; Sassen, Roger; Saffer, Barbara

1987-01-01

203

Hyperaldosteronism - primary and secondary  

MedlinePLUS

Primary and secondary hyperaldosteronism are conditions in which the adrenal gland releases too much of the hormone ... People with primary hyperaldosteronism have a problem with the adrenal gland that causes it to release too much aldosterone. In secondary ...

204

Mineral hydrolysis kinetics  

SciTech Connect

Dissolution rate laws for silicate mineral weathering can be related to kinetics of ligand-exchange reactions. This relation is being tested with an experimental/analytical/theoretical program for measuring the dissolution kinetics of orthosilicate minerals for use in ionic modeling and molecular dynamics computer simulations of solid, aqueous solution, and solid/liquid interface. To date, dissolution rate have been measured for a suite of endmember and mixed-cation orthosilicate minerals (both olivine and willemite structures) as well as a few inosilicate minerals (pyroxenes). Dissolution rates appear to correlate well with solvent exchange rates around the hydrated divalent cations. Siloxane (Si-O-Si) bonds are relatively unreactive at low pH`s close to zero point of neutral charge for quartz. The correlation suggests that silicic acid would be released from the reacting surfaces after protonation and hydration of bonds between divalent metals and structural oxygens; congruent dissolution is confirmed by Rutherford backscattered analysis of the near-surface of an acid-reacted forsterite. In the ionic modeling, except for liebenbergite, there is a general trend of increasing lattice energy with decreasing dissolution rate for endmember and mixed-cation orthosilicate minerals at pH 2. 3 figs, 4 refs.

Westrich, H.R.; Cygan, R.T.; Arnold, G.W. [Sandia National Labs., Albuquerque, NM (United States); Casey, W.H. [California Univ., Davis, CA (United States). Dept. of Land, Air, and Water Resources

1993-07-01

205

[Secondary glomerular nephropathies].  

PubMed

Secondary glomerular lesions are associated with various diseases; diabetes, systemic lupus erythematosus, primary cryoglobulinaemia, cryoglobulinemia and membranoproliferative glomerulonephritis secondary to hepatitis C virus (HCV), ANCA associated vasculitis and their forms limited to kidney (necrotic and crescentic GN), Goodpasture syndrome, HIV associated nephropathies, AL amyloidosis, AA amyloidosis (secondary amyloidosis), GN with non-amyloid organised deposits. PMID:15008219

Lesavre, Philippe

2003-11-30

206

Thorium in mineral products.  

PubMed

Many ores contain low levels of thorium. When these ores are processed, the associated radioactivity can be found in mineral concentrates, intermediates and final products. There is an incentive for industries to remove radioactivity from mineral products to allow the movement and sale of these materials, both nationally and internationally, without the need for licensing. Control of thorium in various products involves the development and optimisation of process steps to be able to meet product specifications. The Australian Nuclear Science and Technology Organisation (ANSTO) has undertaken a range of R & D programmes targeting the treatment of thorium-bearing minerals. This paper discusses the application of a microprobe technique for siting radioactivity in zircon and ilmenite and the problems experienced in measuring the concentrations in solid rare earth products. PMID:11843361

Collier, D E; Brown, S A; Blagojevic, N; Soldenhoff, K H; Ring, R J

2001-01-01

207

Isotopic bone mineralization rates in maintenance dialysis patients  

SciTech Connect

The expanding pool model of radiocalcium kinetics has been used in 13 maintenance dialysis patients to measure bone mineralization rate. No difficulties were met in applying the data to the model, and values for the bone mineralization rate ranged from 0.0 to 2.0 mmol/kg Ca++ per day. The bone histology obtained at the time of the study showed a correlation between the degree of secondary hyperparathyroidism and the bone mineralization rate, with low values of the latter occurring in atypical osteomalacia (two patients) or inactive-looking bone (one patient) and raised values in seven patients. The plasma alkaline phosphatase and immunoassayable parathyroid hormone levels each correlated significantly with the bone mineralization rate. These findings suggest that the technique is valid when applied to hemodialysis patients and provides quantitative information about skeletal calcium metabolism in different types of renal bone disease.

Cochran, M.; Stephens, E.

1983-09-01

208

Mineral find highlights cruise  

NASA Astrophysics Data System (ADS)

Heavy minerals with potential commercial value were discovered last month by the U.S. Geological Survey (USGS) in seafloor deposits off the coasts of Virginia and Georgia. The USGS sent the research vessel J. W. Powell on a 25-day cruise along the East Coast to assess the concentrations of commercially important minerals in that segment of the U.S. Exclusive Economic Zone (EEZ).Assistant Secretary of the Interior Robert Broadbent called the findings of the Powell “promising” and said they served as a “reminder of just how little we do know about the seafloor resources just a few miles offshore.”

Katzoff, Judith A.

209

Minerals Yearbook 1989: Boron  

SciTech Connect

U.S. production and sales of boron minerals and chemicals decreased during the year. Domestically, glass fiber insulation was the largest use for borates, followed by sales to distributors, textile-grade glass fibers, and borosilicate glasses. California was the only domestic source of boron minerals. The United States continued to provide essentially all of its own supply while maintaining a strong position as a source of sodium borate products and boric acid exported to foreign markets. Supplementary U.S. imports of Turkish calcium borate and calcium-sodium borate ores, borax, and boric acid, primarily for various glass uses, continued.

Lyday, P.A.

1990-08-01

210

Minerals Yearbook 1990: Montana.  

National Technical Information Service (NTIS)

Montana's 1990 nonfuel mineral production value was $567.7 million, relatively unchanged from that of 1989. Gains in the production value of portland cement, clays, gold, crushed stone, talc, and zinc offset the decline in values of copper, molybdenum, ph...

R. J. Minarik R. B. McCulloch

1992-01-01

211

Minerals Yearbook, 1988: Minnesota.  

National Technical Information Service (NTIS)

Minnesota's nonfuel mineral production in 1988 was valued at nearly $1.3 billion, about $125 million more than in 1987. Iron ore shipments, which accounted for most of this increase, were at their highest level since 1981. Minnesota ranked eighth national...

J. J. Hill

1988-01-01

212

Minerals Yearbook, 1992: Montana.  

National Technical Information Service (NTIS)

Montana's 1992 nonfuel mineral production value was $539.2 million, a slight increase from that of 1991, according to the U.S. Bureau of Mines. Increases in the production value of lime, construction sand and gravel, and zinc more than offset the decrease...

R. J. Minarik R. B. McCulloch

1994-01-01

213

Minerals Yearbook, 1991: Chromium.  

National Technical Information Service (NTIS)

Dr. Papp, a physical scientist with 20 years' U.S. Bureau of Mines experience, has been the commodity specialist for chromium since 1983. Domestic survey data were prepared by Steve Frauenheim and Robin Johnson, mineral data assistants; chromite world pro...

J. F. Papp

1993-01-01

214

New mineral physics panels  

NASA Astrophysics Data System (ADS)

The AGU Committee on Mineral Physics has formed itself into six panels. The committee chairman is Orson L. Anderson of the Department of Earth and Space Sciences, University of California, Los Angeles; foreign secretary is Robert Liebermann, Department of Earth and Space Sciences, State University of New York, Stony Brook. The six panels are as follows.

215

Energy and Mineral Resources  

NSDL National Science Digital Library

This site contains 16 questions on the topic of energy and mineral resources, which covers energy sources, resource types, and uses of resources. This is part of the Principles of Earth Science course at the University of South Dakota. Users submit their answers and are provided immediate verification.

Heaton, Timothy

216

Minerals Yearbook, 1988: Wyoming.  

National Technical Information Service (NTIS)

The value of nonfuel mineral production in Wyoming rose about 10% in 1988 to $709.8 million. A similar percentage increase in the value of natural sodium carbonate-sodium bicarbonate (soda ash) production accounted for most of the change. Soda ash continu...

K. Starch W. D. Hausel R. E. Harris

1988-01-01

217

Mixtures and mineral reactions  

SciTech Connect

Considerable progress has been made in our understanding of the physicochemical evolution of natural rocks through systematic analysis of the compositional properties and phase relations of their mineral assemblages. This book brings together concepts of classical thermodynamics, solution models, and atomic ordering and interactions that constitute a basis of such analysis, with examples of application to subsolidus petrological problems.

Saxena, S.; Ganguly, J.

1987-01-01

218

Mineral mining equipment  

SciTech Connect

A mineral mining machine hauls itself along a working face by engaging a round link chain. The links of the chain are fed sequentially from link-retaining pockets in a track component arranged around the working face, around a driven sprocket assembly on the machine and returned to the pockets.

Monks, H.

1980-11-25

219

Clay Mineral: Radiological Characterization  

NASA Astrophysics Data System (ADS)

Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906+/-340 Bq kg-1 for 40K, 40+/-9 Bq kg-1 for 226Ra, 75+/-9 Bq kg-1 for 228Ra, 197+/-38 Bq kg-1 for 210Pb, 51+/-26 Bq kg-1 for 238U and 55+/-24 Bq kg-1 for 232Th, considering both kinds of clay.

Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

2008-08-01

220

Minerals Yearbook, 1989: California.  

National Technical Information Service (NTIS)

California ranked second among the States in the value of nonfuel minerals produced in 1989, about 8.8% of the U.S. total. The value of the commodities produced in 1989 increased nearly 6% to $2.85 billion, continuing the steady growth in the State's mine...

F. V. Carrillo J. F. Davis J. L. Burnett

1989-01-01

221

Minerals Yearbook, 1992: California.  

National Technical Information Service (NTIS)

California ranked third in the Nation in total value of nonfuel mineral production in 1992. Reported production valued at $2,345,838,000 was 7.33% of the U.S. total. The value of the commodities produced in California during the year decreased about 7.5% ...

F. V. Carrillo J. F. Davis J. T. Alfors

1994-01-01

222

MINERAL FILLERS IN PAPER  

Microsoft Academic Search

The paper is divided into two parts. In Part 1, after a brief historical introduction the advantages and disadvantages of using mineral fillers in the manufacture of paper are summarised. Details of the origin, methods of production and basic physical properties of kaolin, natural calcium carbonate, precipitated calcium carbonate, talc and titanium dioxide follow. These are supplemented by more limited

Ken Beazley

1991-01-01

223

Oxidants from Pulverized Minerals  

NASA Astrophysics Data System (ADS)

Joel Hurowitz (previously at State University of New York at Stony Brook and now at the Jet Propulsion Laboratory), Nick Tosca, Scott McLennan, and Martin Schoonen (SUNY at Stony Brook) studied the production of hydrogen peroxide from freshly pulverized minerals in solution. Their experiments focused on olivine, augite, and labradorite; silicate minerals of basaltic planetary surfaces, such as the Moon and Mars, that are exposed to the intense crushing and grinding of impact cratering processes. The hydrogen peroxide produced in the experiments was enough to adequately explain the oxidizing nature of Martian regolith first determined by the Viking Landers and the results suggest, for the first time, that mechanically activated mineral surfaces may be an important part of the overall explanation for the Viking Lander biology experiment results. Hurowitz and coauthors further showed that when the pulverized minerals are heat-treated to high temperature under vacuum (to cause dehydroxylation) there is almost a 20 times increase in hydrogen peroxide production, a result which may be highly relevant to lunar dust. These careful studies demonstrate the importance of and concern about reactive dusts on planetary surfaces from two standpoints: the health of astronauts on surface maneuvers who may inadvertently breath it and the viability of possible Martian organic species to survive in such a corrosive, antiseptic surface environment.

Martel, L. M. V.

2007-06-01

224

Bioleaching of Minerals  

SciTech Connect

Bioleaching is the term used to describe the microbial dissolution of metals from minerals. The commercial bioleaching of metals, particularly those hosted in sulfide minerals, is supported by the technical disciplines of biohydrometallurgy, hydrometallurgy, pyrometallurgy, chemistry, electrochemistry, and chemical engineering. The study of the natural weathering of these same minerals, above and below ground, is also linked to the fields of geomicrobiology and biogeochemistry. Studies of abandoned and disused mines indicate that the alterations of the natural environment due to man's activities leave as remnants microbiological activity that continues the biologically mediated release of metals from the host rock (acid rock drainage; ARD). A significant fraction of the world's copper, gold and uranium is now recovered by exploiting native or introduced microbial communities. While some members of these unique communities have been extensively studied for the past 50 years, our knowledge of the composition of these communities, and the function of the individual species present remains relatively limited. Nevertheless, bioleaching represents a major strategy in mineral resource recovery whose importance will increase as ore reserves decline in quality, become more difficult to process (due to increased depth, increased need for comminution, for example), and as environmental considerations eliminate traditional physical processes such as smelting, which have served the mining industry for hundreds of years.

F. Roberto

2002-02-01

225

Minerals Yearbook, 1991: Beryllium.  

National Technical Information Service (NTIS)

Beryllium data are collected from two voluntary surveys of U.S. operations. In 1990, there were eight responses to the 'Beryllium Mineral Concentrate and Beryllium Ore' survey, representing 100% of the total canvassed. U.S. mine production continued to de...

D. A. Kramer

1992-01-01

226

Mineral oil soluble borate compositions  

SciTech Connect

Alkali metal borates are reacted with fatty acids or oils in the presence of a low hlb value surfactant to give a stable mineral oil-soluble product. Mineral oil containing the borate can be used as a cutting fluid.

Dulat, J.

1981-09-15

227

Alphabetical Listing of Mineral Species  

NSDL National Science Digital Library

This directory provides an alphabetical listing of more than 4,000 mineral species. Clicking on each mineral name provides access to information including chemical formula and composition, locality and name origin, physical properties, optical properties, images, and many others.

228

DIAMOND SECONDARY EMITTER  

SciTech Connect

We present the design and experimental progress on the diamond secondary emitter as an electron source for high average power injectors. The design criteria for average currents up to 1 A and charge up to 20 nC are established. Secondary Electron Yield (SEY) exceeding 200 in transmission mode and 50 in emission mode have been measured. Preliminary results on the design and fabrication of the self contained capsule with primary electron source and secondary electron emitter will also be presented.

BEN-ZVI, I.; RAO, T.; BURRILL, A.; CHANG, X.; GRIMES, J.; RANK, J.; SEGALOV, Z.; SMEDLEY, J.

2005-10-09

229

Private Mineral Project - Part 1  

NSDL National Science Digital Library

In this semester-long private mineral project, students become experts on one mineral. They write a paper about their mineral and use key information about it to publish a web page. Information should include provenance, physical properties, composition, recent related literature, photos of samples, optical properties, x-ray pattern, crystallography, economic value, atomic structure, other closely related minerals, associated myths, and a complete list of references based on GSA format.

Perkins, Dexter

230

The mineral nature of asbestos  

Microsoft Academic Search

Fibrous minerals are common in nature but asbestiform minerals are rare. The unique mineralogical characteristic common to all the asbestos minerals is their morphologic form (or habit of crystallization) as polyfilamentous fiber bundles. The individual fibrils within the bundles have a tendency to be very long with a narrow range of diameters and grow with their long fiber axis in

Malcolm Ross; Arthur M. Langer; Gordon L. Nord; Robert P. Nolan; Richard J. Lee; D. Van Orden; John Addison

2008-01-01

231

Mineral Properties -- Learning through Experience  

NSDL National Science Digital Library

Students are each given a mineral and asked to locate all other students in the room with the same mineral (knowing there are a total of 5 different minerals). Once groups form, they need to decide what characteristics are similar for all their samples and ultimately report out to the whole class on their observations.

Wiese, Katryn

232

Electrical conductivity of mantle minerals  

Microsoft Academic Search

Electrical conductivity of mantle minerals Deep electrical conductivity profiles can provide constraints on the thermal and chemical state of the mantle. Especially, electrical conductivity is very sensitive to small amount of hydrogen and iron contents in minerals. Accurate knowledge of electrical conductivity of mantle minerals is needed to constrain water and\\/or iron contents in the mantle as a function of

T. Yoshino; G. Manthilake; M. Nishi; T. Katsura

2006-01-01

233

Common Rock-Forming Minerals  

NSDL National Science Digital Library

This is a collection of images of the common rock-forming minerals. Along with the image, the physical and chemical properties of each mineral are listed. These include: metallic or nonmetallic luster, light or dark color, chemical formula, mineral group, cleavage, general color, hardness, and other characteristics.

Weiland, Tom

234

Minerals yearbook, 1992. Volume 1. Metals and minerals. Annual report  

SciTech Connect

This edition of the Minerals Yearbook discusses the performance of the worldwide mineral and materials industry during 1992 and provides background information to assist in interpreting that performance. Content of the individual Yearbook volumes follows: Volume I, Metals and Minerals, contains chapters on virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on advanced materials, nonrenewable organic materials, and nonferrous metals recycling also were added to the Minerals Yearbook series beginning with the 1989, 1990, and 1991 volumes, respectively. A new chapter on materials recycling has been initiated in this 1992 volume. In addition, a chapter on survey methods used in data collection with a statistical summary of nonfuel minerals and a chapter on trends in mining and quarrying in the metals and industrial mineral industries are included.

Not Available

1992-01-01

235

Minerals yearbook, 1991. Volume 1. Metals and minerals. Annual report  

SciTech Connect

This edition of the Mineral Yearbook discusses the performance of the worlwide minerals and materials industry during 1991 and provides background information to assist in interpreting that performance. Volume 1, Metals and Mineral, contains chapters on virtually all metallic and industrial mineral commodities important to the U.S. economy. Chapters on advanced materials and nonrenewable organic materials also were added to the Minerals Yearbook series beginning with the 1989 and 1990 volumes, respectively. A new chapter on nonferrous metals recycling has been initiated in this 1991 volume. In addition, a chapter on survey methods used in data collection with a statistical summary of nonfuel minerals and a chapter on trends in mining and quarrying in the metals and industrial mineral industries are included.

NONE

1991-12-31

236

Taxation of mineral resources  

SciTech Connect

There has been a substantial increase in recent years in the level of taxation imposed on mining firms by state and local governments. This increase can be attributed to three factors: (1) a heightened awareness that resources are limited in quantity; (2) environmental damage resulting from mining operations has brought demands for just compensations; and (3) significant price increases for some minerals have often been viewed by states as an opportunity to collect additional tax revenue. The broad aim of this book is to provide a comprehensive economic analysis of the effects of mining taxation on the extraction of mineral resources and to offer a set of recommendations for tax policy. The primary objective of this design is to minimize the distortionary incentives created by the taxation. From a practical standpoint, however, one must also recognize the degrees of difficulty in the administration of the various taxes. 90 references, 1 figure, 14 tables.

Conrad, R.F.; Hool, R.B.

1980-01-01

237

Vitamins and minerals  

Microsoft Academic Search

Taking vitamins and minerals to fight the common cold is popular in western countries and thus it is important to find out\\u000a whether or not they are effective. A large number of trials have found that regular vitamin C supplementation shortens the\\u000a duration of colds, and is probably beneficial when administered therapeutically starting soon after the onset of symptoms.\\u000a Zinc

Harri Hemilä

238

Mineralization by nanobacteria  

Microsoft Academic Search

Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and in commercial cell culture serum. In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. Previous models for stone formation

E. Olavi Kajander; Michael Bjorklund; Neva Ciftcioglu

1998-01-01

239

Exploring Bone Mineral Density  

NSDL National Science Digital Library

In this activity, students will explore two given websites to gather information on Bone Mineral Density and how it is measured. They will also learn about X-rays in general, how they work and their different uses, along with other imaging modalities. They will answer guiding questions as they explore the websites and take a short quiz after to test the knowledge they gained while reading the articles.

Vu Bioengineering Ret Program

240

Mineral Physics Activity Sets  

NSDL National Science Digital Library

These assignment sets are designed for a 500-level course in mineral physics for geoscience majors. The activities/problem sets are derived from a course at the University of Washington. They include topics such as Earth models, lattices, x-rays, thermodynamics, elasticity, and lattice vibrations/pressure. Some of the activities elicit the use of MATLAB programming. Supporting materials and spreadsheets in addition to links to class notes and handouts are also provided.

Brown, Michael

241

Enzymatic mineralization of silk scaffolds.  

PubMed

The present study focuses on the alkaline phosphatase (ALP) mediated formation of apatitic minerals on porous silk fibroin protein (SFP) scaffolds. Porous SFP scaffolds impregnated with different concentrations of ALP are homogeneously mineralized under physiological conditions. The mineral structure is apatite while the structures differ as a function of the ALP concentration. Cellular adhesion, proliferation, and colonization of osteogenic MC3T3 cells improve on the mineralized SFP scaffolds. These findings suggest a simple process to generate mineralized scaffolds that can be used to enhanced bone tissue engineering-related utility. PMID:24610728

Samal, Sangram K; Dash, Mamoni; Declercq, Heidi A; Gheysens, Tom; Dendooven, Jolien; Voort, Pascal Van Der; Cornelissen, Ria; Dubruel, Peter; Kaplan, David L

2014-07-01

242

Research in Secondary Reading.  

ERIC Educational Resources Information Center

Summers' annotated bibliographies of secondary reading (1963, 1964), "Review of Educational Research,""Journal of Reading," ERIC/CRIER, and "Research in Education" are listed as resources for all phases of reading. A shifting of trends in the nature and scope of research topics in secondary reading is noted, with diagnosis and treatment,…

Kling, Martin

243

Future of Secondary Services.  

ERIC Educational Resources Information Center

Argues that the major forces related to economic factors that effect the future of secondary services are growth of primary literature and expansion of secondary products; migration of use from print products to tape products; new technology and impact on production of products and services; and redefinition of user as end user. (EJS)

Neufeld, M. Lynne

1983-01-01

244

Secondary fuel delivery system  

DOEpatents

A secondary fuel delivery system for delivering a secondary stream of fuel and/or diluent to a secondary combustion zone located in the transition piece of a combustion engine, downstream of the engine primary combustion region is disclosed. The system includes a manifold formed integral to, and surrounding a portion of, the transition piece, a manifold inlet port, and a collection of injection nozzles. A flowsleeve augments fuel/diluent flow velocity and improves the system cooling effectiveness. Passive cooling elements, including effusion cooling holes located within the transition boundary and thermal-stress-dissipating gaps that resist thermal stress accumulation, provide supplemental heat dissipation in key areas. The system delivers a secondary fuel/diluent mixture to a secondary combustion zone located along the length of the transition piece, while reducing the impact of elevated vibration levels found within the transition piece and avoiding the heat dissipation difficulties often associated with traditional vibration reduction methods.

Parker, David M. (Oviedo, FL) [Oviedo, FL; Cai, Weidong (Oviedo, FL) [Oviedo, FL; Garan, Daniel W. (Orlando, FL) [Orlando, FL; Harris, Arthur J. (Orlando, FL) [Orlando, FL

2010-02-23

245

Investigation of lichens using molecular techniques and associated mineral accumulations on a basaltic flow in a Mediterranean environment  

Microsoft Academic Search

The role of lichens in the breakdown of rocks in various environments is well documented. We investigated the formation of secondary minerals under 13 different fungal species growing on a basaltic flow in Sanliurfa (Turkey) to understand the influence of lichen species on the transformation of minerals in a Mediterranean environment. We used molecular technique (rDNA sequence) to identify 13

Joselito M. Arocena; Tariq Siddique; Ronald W. Thring; Selim Kapur

2007-01-01

246

Mineral industries of Australia, Canada, and Oceania (including a discussion of Antarctica's mineral resources). Mineral perspective  

SciTech Connect

The Bureau of Mines report gives the mineral industry highlights of two of the world's major mineral producing countries, Australia and Canada, and seven Pacific island nations or territories--Fiji, New Caledonia, New Zealand, Papua New Guinea, Republic of Nauru, Solomon Islands, and Vanuatu. The mineral resources of Antarctica are also discussed. Because of the size of the Australian and Canadian mineral industries, summary reviews are presented for each of the States, Provinces, or Territories. The most current information available from all nations is given on major minerals or mineral-commodity production, share of world production, and reserves. Reported also are significant mining companies, locations and capacities of their main facilities, and their share of domestic production. Other information is provided on mineral-related trade with the United States, government mineral policy, energy production-consumption and trade, the mining industry labor force, and prospects for the mineral industry. Maps show the locations of selected mineral deposits, oilfields and gasfields, mines, and processing facilities including iron and steel plants, nonferrous smelters and refineries, and cement plants, as well as infrastructure pertinent to the mineral industry.

Kimbell, C.L.; Lyday, T.Q.; Newman, H.H.

1985-12-01

247

Rocks and Minerals  

NSDL National Science Digital Library

This web page offers a simple illustrated guide to the three rock types- igneous, sedimentary, and metamorphic; and the most common rock-forming mineral groups: quartz, plagioclase feldspars, potassium feldspars, micas, amphiboles, olivine, and calcite. The rock types include extrusive and intrusive igneous rocks, clastic, biologic, and chemical sedimentary rocks, and both foliated and non-foliated metamorphic rocks. A section is included on naming igneous rocks. The igneous rocks tuff and basalt are also discussed, as is sediment. Users are directed to related resources and may print out a simplified rock classification chart.

248

Mechanisms of primary mineral weathering inferred from B isotopes  

NASA Astrophysics Data System (ADS)

Silicate weathered minerals result from a combination of dissolution/precipitation or transformation reactions. Despite their chemical and isotopic compositions as well as their mineralogy record the physico-chemical conditions of their formation and history, the determination of the current state of weathering in soils still remains very challenging. The main difficulties come from a difficult access to the mineral sites actually active during primary mineral transformation and from non-stoichiometric release of site-forming cations. To better characterize how minerals record the conditions of their formation, we coupled analyses of mineralogy with major elements and boron isotopes in a series of primary minerals (biotite, muscovite, K-feldspar and plagioclase) associated in varying amount with their replacement phases (vermiculite, kaolinite, illite…). The minerals are sampled along an acid Alocrisoil profile developed on granitic bedrock from the Breuil-Chenue forest (France). Previous studies have demonstrated that boron occupies different minerals sites (tetrahedron in substitution of Si, or interfoliar sites possibly in direct contact with the surrounding fluid, Williams et al. 2001, Muttik et al. 2011, Voinot et al., in prep.). Voinot et al. (in prep.) have also demonstrated that boron isotopes are very sensitive to silicate transformation or dissolution reactions. In deeper soil layers (100 to 130 cm), kaolinite is found in biotite mineral habitus. Examination of the boron isotopes distribution in those weathered agglomerates points to a boron depletion and a rapid isotopic equilibration with the surrounding soil solution as kaolinite fraction increases. The same - but magnified - trend is observed during shallow weathering mechanisms (20 to 30 cm) of fine particles of biotite (< 200 µm). By contrast, coarse biotite minerals (> 200 µm) evolve to a vermiculite-like product that tends to be enriched in boron (up to three times the initial biotite concentration) but share a common isotopic composition with kaolinite revealing an equilibrium with the solution. Plagioclases dissolve very early in the deepest horizon with a high degree of in-situ kaolinite reprecipitation in their mineral habitus. Here again, the isotopic composition reflect exchange with the soil solution. Muscovite shows no particular weathering mechanism other than dissolution, but isotope shift toward the soil solution value tends to indicate that the reacting boron is mainly located in easy accessible mineral interlayer sites. K-feldspar samples remained unchanged either mineralogically or isotopically. These results suggest an apparent duality between phyllosilicates which are mainly involved in transformation reactions with rapid isotopic equilibration with the surrounding soil solution, whilst tectosilicates show mainly dissolution reactions without evidence of isotopic exchange with the fluid. Depending on their nature, the secondary phases that replace the weathered primary minerals will also play a major role in the boron cycle in soils.

Voinot, A.; Turpault, M.-P.; Chabaux, F.; Lemarchand, D.

2012-04-01

249

Biogenic dissolution of a soil cerium-phosphate mineral  

Microsoft Academic Search

The productivity of many terrestrial ecosystems is controlled or limited by phosphorus bioavailability. Within these ecosystems, nearly all of the bioavailable phosphate is ultimately derived via the weathering of apatite (Ca5(PO4)3 (OH,F,Cl)). Highly insoluble lanthanide phosphate minerals form during apatite weathering and are important secondary phosphorus repositories in soils. Prior studies indicate that these phases can be dissolved via biologically-mediated

JAVIERA CERVINI-SILVA; DAVID A. FOWLE; JILLIAN BANFIELD

2005-01-01

250

Decreased mineralization in hemodialysis patients after subtotal parathyroidectomy  

Microsoft Academic Search

Summary  Many hemodialysis patients undergo subtotal parathyroidectomy (sPTx) because of the complications of severe secondary hyperparathyroidism.\\u000a In some patients, however, renal osteodystrophy fails to regress. In uremia, the high levels of circulating immunoreactive\\u000a parathyroid hormone (iPTH) which accompany osteitis fibrosa are associated with accelerated bone formation. After sPTx, the\\u000a fall in iPTH may decrease mineralization and increase osteoid formation. Bone histomorphometry,

Robert S. Weinstein

1982-01-01

251

ADEPT for Secondary Payloads  

NASA Astrophysics Data System (ADS)

This presentation will inform the EDL community of the capability of ADEPT for delivery of small (sub 1 m diameter) secondary payloads as well as provide status of on-going technology development activities.

Smith, B.; Cassell, A.; Venkatapathy, E.

2014-06-01

252

Mineral dust as ice nuclei in the upper troposphere (Invited)  

NASA Astrophysics Data System (ADS)

Composition, size, and phase are key properties that define the ability of an aerosol particle to initiate ice in cirrus clouds. Properties of cirrus ice nuclei (IN) have not been well constrained due to a lack of systematic measurements in the upper troposphere. In a recent study of several northern hemisphere regions we report the size and composition of sublimated cirrus particles sampled from a high altitude research aircraft using both in situ and offline techniques. Mineral dust was consistently the most abundant particle type in cirrus residuals, suggesting that heterogeneous nucleation was a dominant cirrus formation mechanism in these study regions. Other proposed heterogeneous IN, including biomass burning particles, elemental carbon, and biological material, were not abundant in cirrus residuals. Clear sky measurements show that mineral dust was ubiquitous in the background upper troposphere at levels from ~1 to 100's per liter and typically accounted for 5-40% of the particulate mass. Principal sources of upper tropospheric mineral dust include strong biomass burning events and deep convection, although some evidence suggests that dust aerosol is preferentially scavenged in convective systems. During transport mineral dust accumulates secondary sulfate, nitrate, and organic material that can reduce IN efficiency. Most upper tropospheric dust particles contain secondary material, and coating type and thickness depend on coemissions and the vertical transport mechanism.

Froyd, K.; Cziczo, D. J.; Murphy, D. M.

2013-12-01

253

Bone and mineral metabolism in patients with primary aldosteronism.  

PubMed

Primary aldosteronism represents major cause of secondary hypertension, strongly associated with high cardiovascular morbidity and mortality. Aldosterone excess may influence mineral homeostasis, through higher urinary calcium excretion inducing secondary increase of parathyroid hormone. Recently, in a cohort of PA patients a significant increase of primary hyperparathyroidism was found, suggesting a bidirectional functional link between the adrenal and parathyroid glands. The aim of this study was to evaluate the impact of aldosterone excess on mineral metabolism and bone mass density. In 73 PA patients we evaluated anthropometric and biochemical parameters, renin-angiotensin-aldosterone system, calcium-phosphorus metabolism, and bone mineral density; control groups were 73 essential hypertension (EH) subjects and 40 healthy subjects. Compared to HS and EH, PA subjects had significantly lower serum calcium levels and higher urinary calcium excretion. Moreover, PA patients showed higher plasma PTH, lower serum 25(OH)-vitamin D levels, higher prevalence of vitamin D deficiency (65% versus 25% and 25%; P < 0.001), and higher prevalence of osteopenia/osteoporosis (38.5 and 10.5%) than EH (28% and 4%) and NS (25% and 5%), respectively. This study supports the hypothesis that bone loss and fracture risk in PA patients are potentially the result of aldosterone mediated hypercalciuria and the consecutive secondary hyperparathyroidism. PMID:24864141

Petramala, Luigi; Zinnamosca, Laura; Settevendemmie, Amina; Marinelli, Cristiano; Nardi, Matteo; Concistrè, Antonio; Corpaci, Francesco; Tonnarini, Gianfranco; De Toma, Giorgio; Letizia, Claudio

2014-01-01

254

Bone and Mineral Metabolism in Patients with Primary Aldosteronism  

PubMed Central

Primary aldosteronism represents major cause of secondary hypertension, strongly associated with high cardiovascular morbidity and mortality. Aldosterone excess may influence mineral homeostasis, through higher urinary calcium excretion inducing secondary increase of parathyroid hormone. Recently, in a cohort of PA patients a significant increase of primary hyperparathyroidism was found, suggesting a bidirectional functional link between the adrenal and parathyroid glands. The aim of this study was to evaluate the impact of aldosterone excess on mineral metabolism and bone mass density. In 73 PA patients we evaluated anthropometric and biochemical parameters, renin-angiotensin-aldosterone system, calcium-phosphorus metabolism, and bone mineral density; control groups were 73 essential hypertension (EH) subjects and 40 healthy subjects. Compared to HS and EH, PA subjects had significantly lower serum calcium levels and higher urinary calcium excretion. Moreover, PA patients showed higher plasma PTH, lower serum 25(OH)-vitamin D levels, higher prevalence of vitamin D deficiency (65% versus 25% and 25%; P < 0.001), and higher prevalence of osteopenia/osteoporosis (38.5 and 10.5%) than EH (28% and 4%) and NS (25% and 5%), respectively. This study supports the hypothesis that bone loss and fracture risk in PA patients are potentially the result of aldosterone mediated hypercalciuria and the consecutive secondary hyperparathyroidism.

Petramala, Luigi; Zinnamosca, Laura; Settevendemmie, Amina; Marinelli, Cristiano; Nardi, Matteo; Concistre, Antonio; Corpaci, Francesco; Tonnarini, Gianfranco; De Toma, Giorgio; Letizia, Claudio

2014-01-01

255

Acidophiles in bioreactor mineral processing  

Microsoft Academic Search

Mineral processing in bioreactors has become established in several countries during the past decade with industrial application\\u000a of iron- and sulfur-oxidizing bacteria to release occluded gold from mineral sulfides. Cobalt extraction in bioreactors has\\u000a also been commercialized, and development of high-temperature biooxidation of copper sulfides has reached pilot-plant scale.\\u000a A variety of potentially useful mineral sulfide-oxidizing thermophiles have been recognized,

P. R. Norris; N. P. Burton; N. A. M. Foulis

2000-01-01

256

Microelectrophoresis of selected mineral particles  

NASA Technical Reports Server (NTRS)

Particle mobilities of ilmenite, labradorite plagioclase, enstatite pyroxene, and olivine were measured with a Rank microelectrophoresis system to evaluate indicated mineral separability. Sodium bicarbonate buffer suspension media with and without additives (0.0001 M DTAB and 5 percent v/v ethylene glycol) were used to determine differential adsorption by mineral particles and modification of relative mobilities. Good separability between some minerals was indicated; additives did not enhance separability.

Herren, B. J.; Tipps, R. W.; Alexander, K. D.

1982-01-01

257

MICROBIOLOGY: How Bacteria Respire Minerals  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: Some bacteria respire minerals; that is, they harvest energy from minerals through using them as electron acceptors. Many details of this respiration process have remained obscure. In her Perspective, Newman highlights the study by Lower et al., who have used a customized atomic force microscope to observe bacteria during mineral respiration.

Dianne K. Newman (California Institute of Technology;Division of Geological and Planetary Sciences)

2001-05-18

258

Mineral nanoparticles in dispersed soils  

Microsoft Academic Search

The chemical-mineral composition and morphological features of mineral nanoparticles of clay soils have been studied. In the\\u000a clay soils of the Moscow moraine, nanoparticles are found to be localized in the surface microcavities of sand and silt grains\\u000a covered with clay films. They have predominantly anisometric configurations and comprise mainly mixed-layered clay minerals\\u000a and ferric oxides. The distinctive features of

V. N. Sokolov; M. S. Chernov; V. G. Shlykov; O. V. Razgulina; D. I. Yurkovets; V. V. Krupskaya

2008-01-01

259

Secondary psychoses: an update  

PubMed Central

Psychotic disorders due to a known medical illness or substance use are collectively termed secondary psychoses. In this paper, we first review the historic evolution of the concept of secondary versus primary psychosis and how this distinction supplanted the earlier misleading classification of psychoses into organic and functional. We then outline the clinical features and approach to the diagnosis of secondary psychotic disorders. Features such as atypical presentation, temporal relation to detectable medical cause, evidence of direct physiological causal relationship to the etiological agent, and the absence of evidence of a primary psychotic illness that may better explain the presentation suggest consideration of a secondary psychosis. Finally, we discuss how careful studies of secondary psychotic disorders can help elucidate the pathophysiology of primary, or idiopathic, psychotic disorders such as schizophrenia. We illustrate this issue through a discussion of three secondary psychotic disorders — psychoses associated with temporal lobe epilepsy, velocardiofacial syndrome, and N-methyl D-aspartate (NMDA) receptor encephalitis — that can, respectively, provide neuroanatomical, genetic, and neurochemical models of schizophrenia pathogenesis.

Keshavan, Matcheri S; Kaneko, Yoshio

2013-01-01

260

Carbonate-mineral/water interactions in sulfide-rich mine tailings  

NASA Astrophysics Data System (ADS)

The chemical composition and mineralogy of coatings on carbonate minerals from mine tailings have been studied using aqueous geochemical methods, Time-of-Flight Laser-Ionization Mass Spectrometry (TOF-LIMS) and Transmission Electron Microscopy (TEM). The goal is to study major and trace element partitioning between the aqueous and solid phase, and to infer mechanisms that control the concentrations of elements in the pore water of sulfide-rich mine tailings. Pore-water samples and carbonate-mineral grains were collected from four geochemically distinct zones within the tailings. Oxidation of sulfide minerals near the surface results in a large range in pore-water pH (3.85 to 6.98) and aqueous concentrations of metals and sulfate. With increasing depth in the tailings, mineral-water interactions lead to increasing pH, and decreasing concentrations of metals and sulfate. Calculated mineral saturation indices, trends in the abundance of Ca, Fe, Mg and Mn in TOF-LIMS profiles through the secondary coatings, and electron diffraction patterns obtained from the coatings, suggest that precipitation/dissolution of jarosite-group minerals, gypsum, goethite, akaganéite, amorphous Fe oxyhydroxides and siderite control the aqueous Ca, Fe, Na, K and SO 4 concentrations. The occurrence of secondary coatings on primary minerals is widespread, and reactions with the secondary minerals, rather than the primary mineral substrate, probably represent the principal controls on trace-element distributions in the pore water. The data indicate that adsorption, surface-complexation and co-precipitation reactions are important controls on the concentrations of trace elements in the pore water. The occurrence of siderite coatings on the surface of ankerite grains suggests that Fe-bearing dolomite-structure carbonate minerals dissolve incongruently. This corroborates inferences made by previous workers that solubility differences between calcite and siderite lead to calcite dissolution and siderite precipitation during acid neutralization. The accumulation of secondary coatings will diminish the rate of mineral-dissolution reactions involving the primary minerals. Consequently, the use of kinetic rate constants obtained from the literature for simulating the dissolution of primary mineral phases such as the carbonates and alumino-silicates will likely overestimate the actual rates.

Al, Tom A.; Martin, Chris J.; Blowes, David W.

2000-12-01

261

High-Silica Rock Coatings on Mars: Constraining Secondary Silicate Mineralogy and Chemical Weathering Processes on Mars  

Microsoft Academic Search

Thermal Emission Spectrometer (TES) data have been fundamental to understanding Martian surface mineralogy. These data, however, require careful modeling based on laboratory spectroscopic measurements, and modeling of some minerals for Mars has been equivocal. Due to high degrees of spectral similarity, it is difficult to distinguishing silicate glass, clay minerals, zeolites, palagonitized glass, and other secondary products such as amorphous

M. D. Kraft; J. R. Michalski; T. G. Sharp

2003-01-01

262

Minerals yearbook: The mineral industry of Mexico. 1988 international review  

SciTech Connect

Mexico is one of the major mineral-producing countries in the world, continuing in 1988 a role that the nation had assumed since the first European settlement of the Western Hemisphere. With respect to nonfuel minerals, Mexico was the world's leading producer of bismuth and silver; was among the top 5 producers of barite, fluorspar, graphite, molybdenum, and strontium; and was among the top 10 producers of antimony, white arsenic, cadmium, copper, lead, manganese, mercury, salt, selenium, sulfur, and zinc. In the mineral fuels sector, Mexico was the sixth largest producer of crude oil and ranked eighth in terms of proven oil reserves. In addition, Mexico was the largest foreign supplier of crude oil and cement to the United States. Topics discussed in the report include: Government policies and programs; Production; Trade; Commodity review--Metals, Industrial minerals, and Mineral fuels.

Machamer, J.F.

1988-01-01

263

Mineral Detector for Igneous Rocks  

NASA Astrophysics Data System (ADS)

We present a Raman spectral analysis tool that uses machine learning algorithms to classify pure minerals in igneous rocks. Experiments show greater than 90% accuracy classifying a test set of pure minerals against a database of similar reference minerals using an artificial neural network. Efforts are currently underway to improve this tool for use as a mineral detector in rock samples, an important milestone toward autonomously classifying rocks based on spectral, and previous imaging work. Although pure mineral classification has been widely successful, applying the same methods to rocks is difficult because the spectra may represent a combination of multiple, and often competing, mineral signatures. In such cases some minerals may appear with more intensity than others resulting in masking of weaker minerals. Furthermore, with our particular spectrometer (852 nm excitation, ~50 micron spot size), minerals such as potassium feldspar fluoresce, both obscuring its characteristic Raman features and suppressing those of weaker minerals. For example, plagioclase and quartz, two key minerals for determining the composition of igneous rocks, are often hidden by minerals such as potassium feldspar and pyroxene, and are consequently underrepresented in the spectral analysis. These technicalities tend to skew the perceived composition of a rock from its actual composition. Despite these obstacles, an experiment involving a training set of 26 minerals (plagioclase, potassium feldspar, pyroxene, olivine, quartz) and a test set of 57 igneous rocks (basalt, gabbro, andesite, diorite, dacite, granodiorite, rhyolite, granite) shows that generalizations derived from their spectral data are consistent with expected trends: as rock composition goes from felsic to mafic there is a marked increase in the detection of minerals such as plagioclase and pyroxene along with a decrease in the detection of minerals such as quartz and potassium feldspar. The results suggest that phaneritic rocks are especially good candidates for compositional characterization based on spectral analysis. Aphanitic rocks, whose expected trends were not fully met due to the technicalities mentioned earlier, benefit from our previous imaging analysis work where visual attributes (texture and color) are obtained from color photos. Earlier experiments using 266 igneous rock samples (andesite, basalt, rhyolite, granite, granodiorite, and diorite) correctly classified rocks as felsic, intermediate, or mafic with 79%, 63%, and 58% accuracy, respectively [1]. [1] S. T. Ishikawa, V. C. Gulick. AGU 2008 Fall Mtg.

Ishikawa, S. T.; Hart, S. D.; Gulick, V. C.

2010-12-01

264

Minerals yearbook, 1988: Thorium  

SciTech Connect

Mine production of monazite, the principal source of thorium, decreased slightly in 1988. Associated Minerals (USA) Inc. was the only domestic monazite producer. Monazite produced in the United States was exported, and the thorium products used domestically were derived from imported materials, existing company stocks, and thorium nitrate released from the National Defense Stockpile. Major nonenergy uses were in refractory applications, ceramics, and mantles for incandescent lanterns. The only energy use of thorium in the United States was in the high-temperature gas-cooled (HTGC) nuclear reactor at Fort St. Vrain, CO. Topics discussed in the report include domestic data coverage, legislation and government programs, domestic production, consumption and uses, stocks, prices, foreign trade, world capacity, and world review--(Australia, Brazil, Madagascar, Mozambique).

Hedrick, J.B.

1988-01-01

265

Mineralization by nanobacteria  

NASA Astrophysics Data System (ADS)

Nanobacteria are the smallest cell-walled bacteria, only recently discovered in human and cow blood and in commercial cell culture serum. In this study, we identified with energy-dispersive x-ray microanalysis and chemical analysis that all growth phases of nanobacteria produce biogenic apatite on their cell envelope. Fourier transform IR spectroscopy revealed the mineral as carbonate apatite. Previous models for stone formation have lead to a hypothesis that an elevated pH due to urease and/or alkaline phosphatase activity are important lithogenic factors. Our results indicate that carbonate apatite can be formed without these factors at pH 7.4 at physiological phosphate and calcium concentrations. Due to their specific macromolecules, nanobacteria can produce apatite very efficiency in media mimicking tissue fluids and glomerular filtrate and rapidly mineralizing most of available calcium and phosphate. This can be also monitored by (superscript 85)Sr incorporation and provides a unique model for in vitro studies on calcification. Recently, bacteria have been implicated in the formation of carbonate (hydroxy)fluorapatite in marine sediments. Apatite grains are found so commonly in sedimentary rocks that apatite is omitted in naming the stone. To prove that apatite and other minerals are formed by bacteria would implicate that the bacteria could be observed and their actions followed in stones. We have started to approach this in two ways. Firstly, by the use of sensitive methods for detecting specific bacterial components, like antigens, muramic acid and nucleic acids, that allow for detecting the presence of bacteria and, secondly, by follow-up of volatile bacterial metabolites observed by continuous monitoring with ion mobility spectrometry, IMCELL, working like an artificial, educatable smelling nose. The latter method might allow for remote real time detection of bacterial metabolism, a signature of life, in rocks via fractures of drillholes with or without injected substrate solutions. Nanobacteria may provide a model for primordial life-forms, such as replicating clay crystallites in a sandstone, where minerals and metal atoms associated to membranes, may play catalytic and structural roles reducing the number of enzymes and structural proteins needed for life. Such simple metabolic pathways may support the 10,000-fold slower growth rate of nanobacteria, as compared to the usual bacteria. They may also explain the endurability of this life-form in extreme environmental conditions. Altogether such properties do suggest that nanobacteria may have evolved from environmental sources, such a shot springs, to take advantage of the steady-state calcium and phosphate supply of the mammalian blood. Based upon our findings of nanobacteria, a novel theory for the early development of life, based on apatite-mediated chemistry on membranes selecting itself for its own catalytical machinery, is presented.

Kajander, E. Olavi; Bjorklund, Michael; Ciftcioglu, Neva

1998-07-01

266

Protein- mediated enamel mineralization  

PubMed Central

Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth.

Moradian-Oldak, Janet

2012-01-01

267

Adsorption of reovirus by minerals and soils.  

PubMed Central

Adsorption of [35S]methionine-labeled reovirus by 30 dry soils, minerals, and finely ground rocks suspended in synthetic freshwater at pH 7 was investigated to determine the conditions necessary for optimum virus removal during land application of wastewaters. All of the minerals and soils studied were excellent adsorbents of reovirus, with greater than 99% of the virus adsorbed after 1 h at 4 degrees C. Thereafter, virus remaining in suspension was significantly inactivated, and within 24 h a three to five log10 reduction in titer occurred. The presence of divalent cations, i.e., Ca2+ and Mg2+, in synthetic freshwater enhanced removal, whereas soluble organic matter decreased the amount of virus adsorbed in secondary effluent. The amount of virus adsorbed by these substrates was inversely correlated with the amount of organic matter, capacity to adsorb cationic polyelectrolyte, and electrophoretic mobility. Adsorption increased with increasing available surface area, as suspended infectivity was reduced further by the more finely divided substrates. However, the organic content of the soils reduced the level of infectious virus adsorbed below that expected from surface area measurements alone. The inverse correlation between virus adsorption and substrate capacity for cationic polyelectrolyte indicates that the adsorption of infectious reovirus particles is predominately a charged colloidal particle-charged surface interaction. Thus, adsorption of polyelectrolyte may be useful in predicting the fate of viruses during land application of sewage effluents and sludges.

Moore, R S; Taylor, D H; Reddy, M M; Sturman, L S

1982-01-01

268

Lung Cancer in Uranium Miners.  

National Technical Information Service (NTIS)

This paper analyese the clinical data of 39 uranium miners with lung cancer and of 20 patients with lung cancer who have not been exposed to uranium as control. The age of uranium miners with lung cancer was 36-61 with an average of 48.8, nine years earli...

Zhou C. Fan J. Wang L. Huang Y. Nie G

1987-01-01

269

Analysis of Minerals in Coal.  

National Technical Information Service (NTIS)

The objective of this work was to determine the sources and magnitudes of the errors associated with the analysis of mineral matter in coal. A radio-frequency low temperature asher was used to determine the quantity of mineral matter in the coal and to se...

F. V. Stohl

1980-01-01

270

The minerals potential of Nepal  

Microsoft Academic Search

Historically, Nepal has relied on its agricultural sector to sustain economic development. However, given rapid population growth, the nation may find it necessary to develop its mineral base in order to promote economic growth and stability. This paper presents a mineral resource assessment of Nepal and its five development regions, primarily to make an estimate based on geology of the

Dibya R. Kansakar; James P. Dorian; Allen L. Clark

1986-01-01

271

From Mountain Men to Miners.  

ERIC Educational Resources Information Center

Examines three of the changes wrought by coal mining: (1) the miner's working conditions; (2) the establishment of company towns; and (3) the violence that ensued when miners from Harlan County, Kentucky, referred to as "Bloody Harlan," tried to better their lives by joining labor unions. (CMK)

Stevens, Robert L.; Fogel, Jared A.

1999-01-01

272

Evaporates, petroleum and mineral resources  

SciTech Connect

This book covers oxide minerals under the following topics: oxygen fugacity and its petrologic importance; crystal chemistry of oxides and oxyhydroxides; petrogenetic indicators; oxygen barometry of spinel peridotites; iron-titanium oxides in igneous rocks; oxide minerals in metamorphic rocks; and magnetic petrology.

Melvin, J.L.

1991-01-01

273

Acidophiles in bioreactor mineral processing  

NSDL National Science Digital Library

This scientific paper provides a brief introduction into the use and development of industrial mineral-processing bioreactors and reviews the variety of microfloral species used in bioreactors. Additionally, the authors discuss recent microbiological and process developments with thermoacidophiles that could expand the range of mineral sulfides processed commercially using microorganisms. A subscription to Extremophiles is required to access this article electronically.

Norris, P. R.; Burton, N. P.; Foulis, N. A.; Inc., Springer-Verlag T.

274

Compensation of Navajo Uranium Miners  

NSDL National Science Digital Library

This site addresses policy issues of the compensation of Navajo uranium miners. The site provides an annotated index of current issues, legislation, papers and presentations, books, and links that lead to more information on uranium miners. Imbedded links throughout the text lead to related information.

Project, World I.

275

Mineral Cleavage: a practical experiment  

NSDL National Science Digital Library

In this geology activity, students investigate the physical property of mineral cleavage by physically trying to break down a block of halite and describing the results. This lab addresses many misunderstandings non-majors have about the physical properties of minerals and includes a brief write up of their conclusions.

Browning, Sharon

276

Nell-1 Enhanced Bone Mineralization.  

National Technical Information Service (NTIS)

This invention pertains to the discovery that the human NELL-1 gene induces or upregulates bone mineralization. The NELL-1 gene or gene product thus provides a convenient target for screening for modulators of bone mineralization. In addition, NELL-1 can ...

K. Ting

2003-01-01

277

Mineral Resources and the Environment.  

ERIC Educational Resources Information Center

This report presents the findings and recommendations of panels created by the Committee on Mineral Resources and the Environment (COMRATE) to study four topic areas of mineral resources and the environment. The topic areas studied by the panels were: technology, supply, the environment, and demand. Section I, the report of the technology panel,…

National Academy of Sciences, Washington, DC.

278

Bio/organic compound detection using sodium sulfate minerals: Implications in the search for life on Mars and Europa  

NASA Astrophysics Data System (ADS)

With the discovery of Na-sulfate minerals (thenardite, mirabilite) on Mars and Europa, recent studies using these minerals have focused on their ability to assist in the detection of biosignatures. On Earth, biotic and biotic processes can assist in the formation and deposition of these minerals. A primary objective of these studies is the detection of bio/organic compounds that may be associated with the mineral. These biosignatures would imply biological involvement during mineral formation. The following research presents a series of natural and synthetic investigations to determine if biological activity is associated with Na-sulfate mineralization, and if these minerals can assist in detecting bio/organic compounds. Biological activity associated with the formation of Na-sulfate deposits in the basaltic subsurface of Craters of the Moon National Monument, Idaho was examined by laser desorption Fourier transform mass spectrometry (LD-FTMS), infrared spectroscopy and sulfur isotopic fractionation. These experiments conclude that bio/organic compounds are associated with the secondary Na-sulfate minerals, giving evidence of biological involvement in the mineralization of these deposits. LD-FTMS results of the synthetic bio/organic-mineral combinations show the potential of Na-sulfate minerals to assist in the detection and identification of bio/organic compounds. These results prove the importance of Na-sulfate minerals for future exploration missions that are likely to use LDMS to search for signs of life in the solar system.

Richardson, Charles Doc

279

Reactivity of Reservoir-Caprock Minerals in the Context of Geologic Carbon Sequestration  

NASA Astrophysics Data System (ADS)

Alteration of mineral surfaces during a geologic carbon sequestration project may have significant effects on reservoir/caprock porosity, permeability, and mineral wetting properties, indirectly affecting CO2 injectivity or distribution of the injection plume. Experimental studies were carried out to assess the potential for surface alteration of reservoir-caprock minerals upon exposure to humidified CO2/air atmosphere, CO2-saturated water, and wet supercritical CO2 (scCO2). Mineral samples (albite, orthoclase, labradorite, and muscovite) were exposed to a varying environmental conditions including immersed systems, in equilibrium with ambient-pressure air and with CO2 at 40 deg C and 50 deg C; samples exposed to wet CO2 at relative humidity of 60% (40 deg C) and 80% (50 deg C); and wet scCO2 at 50 deg C and 12 MPa (1750 psi). The ambient pressure conditions provide a baseline for comparison of the surface alteration for the experiments at geologically relevant temperature and pressure (1750 psi and 50 deg C), where the mineral samples were exposed to wet scCO2 at 80% P/Psat. All samples were analyzed by SEM/EDX, and in the case of samples immersed in water, by ICP-OES. For samples prepared under ambient pressure, immersed samples showed variable degrees of pitting and secondary mineral formation. Under humid conditions, only albite showed clear evidence of surface dissolution and secondary mineral formation; the surface alteration increased with increasing RH. Immersed samples under ambient pressure show extensive pitting for both air and CO2 atmospheres, while the 1 bar CO2 atmosphere produced much less secondary mineral formation relative to the 1 bar air atmosphere. In ambient pressure systems, secondary mineral formation was localized, while samples exposed to humid scCO2 samples exhibited secondary mineralization that is widespread over the mineral surface. These results imply that wet scCO2 has a greater potential for surface alteration than samples exposed to humid CO2 at ambient pressure or those in CO2-saturated aqueous solutions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Matteo, E.; Bryan, C. R.; Wang, Y.; Dewers, T. A.; Heath, J. E.

2012-12-01

280

Pulmonary complications in lead miners  

SciTech Connect

We carried out a study to assess the prevalence of respiratory disease in lead miners and to investigate the roles of silica and lead. We used a questionnaire for symptoms and examinations for signs of respiratory disease, chest roentgenograms, and spirometric study in 45 lead miners. Six underwent bronchoscopy and transbronchial lung biopsy (TBB) and five lung lead analysis. Lung lead levels from five patients with no occupational lead exposure were obtained for comparison. Results showed restriction in five of 45 and reticulonodular opacities in 16 of 45 workers. Squamous metaplasia and other histopathologic changes were observed, although silicotic nodules were absent by TBB. Lung lead levels above those of control subjects were observed in four of five lead miners. These findings show that lead miners are at risk for lung disease. Although silica is a likely cause, elevated lung lead content found in these miners merits further investigation.

Masjedi, M.R.; Estineh, N.; Bahadori, M.; Alavi, M.; Sprince, N.L.

1989-07-01

281

Adverse possession of subsurface minerals  

SciTech Connect

Concepts applicable to adverse possession of subsurface minerals are generally the same as those that apply to adverse possession of all real estate. However, special requirements must be satisfied in order to perfect title to subsurface minerals by adverse possession, particularly when there has been a severance of the true title between surface and subsurface minerals. In those jurisdictions where senior and junior grants came from the state or commonwealth covering the same or some of the same land and in those areas where descriptions of land were vague or not carefully drawn, adverse possession serves to solidify land and mineral ownership. There may be some public, social, and economic justification in rewarding, with good title, those who take possession and use real estate for its intended use, including the extraction of subsurface minerals. 96 refernces.

Bowles, P.N.

1983-01-01

282

Secondary drowning in children.  

PubMed Central

Secondary drowning (and near-drowning) is one of the post-immersion respiratory syndromes. It is defined as deterioration of pulmonary function that follows deficient gas exchange due to loss or inactivation of surfactant. A review of 94 consecutive cases of near-drowning in childhood showed that this syndrome occurred in five (5%) cases. Its onset was usually rapid and characterised by a latent period of one to 48 hours of relative respiratory well-being. It occurred more rapidly after immersion in fresh water. The two children immersed in salt water died of secondary drowning, while the three immersed in fresh water recovered completely. If it is anticipated, recognised, and treated vigorously prognosis of secondary drowning is good in fresh water cases but bad after salt water immersion.

Pearn, J H

1980-01-01

283

Secondary differential operators  

NASA Astrophysics Data System (ADS)

Let ? be an arbitrary sustem of partial (non-linear differential equations. Higher infinitesimal sysmmetries of ? may be interpreted as vector fields on the «manifoldå Sol ? of all local solution of this system. The paper deals with construction of differential operators of arbitrary orders on Sol ?. These approaches to construction of the theory of these operators, geometric and functional are presented, and their equivalence is proved when ? is the trivial equation. Coincidence of «extrinsicå and «intrinsicå geometric secondary operator is proved for an arbitrary system ?. It is shown that each geometric secondary operator may be approximated by a sum of compositions of evolution differentiations with any possible accuracy, a description of geometric secondary operators in local coordinates is algo given. These results are obtained by studying the geometry of finite jets and infinitely prolonged equations.

Gusyatnikova, V. N.; Vinogradov, A. M.; Umaguzhin, V. A.

284

Improve secondary containment  

SciTech Connect

Secondary containment systems (SCS) are required by EPA regulations for owners or operators of facilities using tank systems for storing or treating hazardous waste. One of the most common methods for secondary containment is to build a lined structure surrounding the primary containment tanks. This often consists of a concrete wall and flow lined with materials capable of containing the hazardous waste if the primary containment system fails. Several factors should be evaluated in the design of the lined SCS. These are reviewed in this article.

Matson, L. (Matson and Holland, League City, TX (US))

1991-03-01

285

Secondary syphilis and HIV  

PubMed Central

Syphilis has been termed the “great mimic” due to its versatile and varied disease presentations. Dermatological findings are associated with the secondary phase of the disease and typically consist of a generalized papular eruption that can involve the palms and soles, genitals, and mucous membranes. Patients with syphilis and concomitant HIV infection may have altered presentations. We report a case of a 41-year-old HIV-positive man who presented with a papular rash of a few months' duration and was diagnosed with secondary syphilis.

Dhaliwal, Shagun; Patel, Mahir

2012-01-01

286

Vienna RNA secondary structure server  

Microsoft Academic Search

The Vienna RNA secondary structure server provides a web interface to the most frequently used functions of the Vienna RNA software package for the analysis of RNA secondary structures. It currently offers prediction of secondary structure from a single sequence, prediction of the consensus secondary structure for a set of aligned sequences, and the design of sequences that will fold

Ivo L. Hofacker

2003-01-01

287

Mineral composition of the modern bottom sediments of the White Sea  

NASA Astrophysics Data System (ADS)

The mineral composition of the modern bottom sediments were studied in the White Sea. The single terrigenous-mineralogical province is defined; it is characterized by the mineral association of amphibole, epidote, garnet, and pyroxene. Five regions are assigned in the White Sea in accordance with the mineral composition of the surface bottom sediments. We argue that the granite-metamorphic rock complexes of the Baltic Shield are the main source of the modern sediments in the White Sea, while the East European Craton (Russian Platform) plays a secondary role.

Gusakova, A. I.

2013-03-01

288

Effect of the advent and diversification of vascular land plants on mineral weathering through geologic time  

NASA Astrophysics Data System (ADS)

The origin of vascular land plants in the Silurian and their subsequent diversification have had a major effect on mineral weathering through geologic tune. The presence of vascular plants reduces the stability of soil minerals through a net export of ions from soil waters and through the release of complexing organic acids by root mycorrhizae. Additional factors that dictate the nature of plant-induced mineral weathering are (1) the differences in nutrient dynamics between evergreen and deciduous species; (2) the role of specific nutrient sinks (biomass storage and secondary soil mineralization) and outputs (runoff, etc.) in plant ecosystems; and (3) the effect of long- and short-term ecosystem disturbances. First-order increases in overall mineral weathering probably took place in the middle Paleozoic and early Tertiary, following the initial colonization and diversification of land plants and the radiation of deciduous angiospenns. Second-order fluctuations would typify time intervals where paleoecosystem disturbances were maximized, such as periods of climatic instability.

Knoll, Martin A.; Calvin James, W.

1987-12-01

289

Subarctic weathering of mineral wastes provides a sink for atmospheric CO(2).  

PubMed

The mineral waste from some mines has the capacity to trap and store CO(2) within secondary carbonate minerals via the process of silicate weathering. Nesquehonite [MgCO(3)·3H(2)O] forms by weathering of Mg-silicate minerals in kimberlitic mine tailings at the Diavik Diamond Mine, Northwest Territories, Canada. Less abundant Na- and Ca-carbonate minerals precipitate from sewage treatment effluent deposited in the tailings storage facility. Radiocarbon and stable carbon and oxygen isotopes are used to assess the ability of mine tailings to trap and store modern CO(2) within these minerals in the arid, subarctic climate at Diavik. Stable isotopic data cannot always uniquely identify the source of carbon stored within minerals in this setting; however, radiocarbon isotopic data provide a reliable quantitative estimate for sequestration of modern carbon. At least 89% of the carbon trapped within secondary carbonate minerals at Diavik is derived from a modern source, either by direct uptake of atmospheric CO(2) or indirect uptake though the biosphere. Silicate weathering at Diavik is trapping 102-114 g C/m(2)/y within nesquehonite, which corresponds to a 2 orders of magnitude increase over the background rate of CO(2) uptake predicted from arctic and subarctic river catchment data. PMID:21854037

Wilson, Siobhan A; Dipple, Gregory M; Power, Ian M; Barker, Shaun L L; Fallon, Stewart J; Southam, Gordon

2011-09-15

290

Influence of abiotic stress signals on secondary metabolites in plants.  

PubMed

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory. PMID:22041989

Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

2011-11-01

291

Influence of abiotic stress signals on secondary metabolites in plants  

PubMed Central

Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory.

Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

2011-01-01

292

Stability of Minerals in a Plasma  

NASA Astrophysics Data System (ADS)

We report here the results of an experiment designed to determine whether a group of silicate, oxide, sulfide, and metal substrates would remain stable or decompose under the highly energetic conditions of a plasma in which diamonds can form metastably. Using a microwave plasma reactor, we exposed the substrates to a plasma consisting of 99.5% hydrogen and 0.5% methane for 24 hr. The temperature of the substrate was approximately 950 degrees C, the pressure of the vacuum chamber was approximately 45 mbar, and the flow rate of the gas mix was approximately 200 cm^3/s. The silicate substrates were olivine, plagioclase, augite, nepheline, pyrope, hornblende, serpentine, and phlogopite; oxide substrates were magnetite and hematite; sulfide substrates were troilite, pentlandite, and pyrrhotite; and metal substrates were iron, nickel, kamacite, and taenite. Metastable diamonds formed on all the silicate substrates except nepheline. There was no diamond formation on any of the oxide, sulfide, or metal substrates. In every instance where diamonds did not grow the substrates were covered with thick secondary deposits. A substantial amount of pitting was observed on the surfaces of all the silicate substrates except nepheline. There is evidence for the loss of a substantial amount of silicon from at least three silicate substrates (e.g., plagioclase, anorthite, and pyrope in a Ca-rich groundmass). A thick layer of platelike Al-rich secondary deposits (possibly metallic Al and/or corundum) formed on the nepheline substrate. The magnetite, hematite, troilite, pentlandite, pyrrhotite, iron, kamacite, and taenite substrates decomposed significantly. Thick, dark, highly porous secondary iron-rich deposits formed on the surfaces of these substrates. These iron-rich deposits may consist of metallic Fe, FeC, and/or FeS and may be reaction products resulting from the interaction of the plasma and substrates. Other secondary deposits common to the silicates were iron (possibly in the form of metallic Fe, iron carbide, and/or iron sulfide) and calcium (possibly in the form of elemental Ca and/or oldhamite). Secondary iron typically formed porous, loosely bound aggregates, often containing small (0.1-micrometer) spheroids. Fibers approximately 0.05 micrometers in diameter and 10-30 micrometers in length were observed on substrates containing a substantial amount of Ca (e.g., plagioclase, augite, anorthite, and pyrope in a Ca-rich groundmass). The initial presence of Ca in the substrates, loss of Si from the substrates, and growth of fibers on substrates may be related. Samples were run in groups of seven and secondary mineral formation, at least in part, resulted from cross contamination. We can infer from this cross contamination that Fe, Si, Ca, and S were fractionated from some substrates, incorporated into the plasma, and then deposited in different morphologic forms. These forms include fibers, fibrous networks, iron-rich, porous, loosely bound aggregates, and spheroids. The pressure and temperature conditions used in this experiment can be found in the atmospheres of red giant stars. The results of this experiment suggest that most of the minerals used as substrates would not be stable under conditions that favor the metastable growth of diamonds. However, morphologic structures similar to those produced on the substrates in this experiment may also exist in the atmospheres of red giant stars.

Kern, C. M.; Witkowski, R. E.; Cassidy, W. A.

1993-07-01

293

From Primary to Secondary  

ERIC Educational Resources Information Center

This author discusses her decision to move to secondary school to teach mathematics, after having taught and been a mathematics manager in primary schools for six years. She states that this was a valuable experience and sparked her interest in the transition experiences of students, particularly in mathematics. Research (Evangelou et al, 2008,…

Anderson, Lyn

2011-01-01

294

Secondary Syphilitic Lesions  

PubMed Central

An important theme that emerges from all early historical accounts is that in addition to the decreased virulence of Treponema pallidum, the incidence of secondary syphilis has decreased drastically over the past three centuries. Even in the early 20th century, most syphilologists were of the opinion that the disease had undergone changes in its manifestations and that they were dealing with an attenuated form of the spirochete. Such opinions were based primarily on the observations that violent cutaneous reactions and fatalities associated with the secondary stage had become extremely rare. The rate of primary and secondary syphilis in the United States increased in 2002 for the second consecutive year. After a decade-long decline that led to an all-time low in 2000, the recent trend is attributable, to a large extent, by a increase in reported syphilis cases among men, particularly homosexual and bisexual men having sex with men. The present review addresses the clinical and diagnostic criteria for the recognition of secondary syphilis, the clinical course and manifestations of the disease if allowed to proceed past the primary stage of disease in untreated individuals, and the treatment for this stage of the disease.

Baughn, Robert E.; Musher, Daniel M.

2005-01-01

295

Secondary Dance Instructional Guide.  

ERIC Educational Resources Information Center

This manual provides guidelines for dance teachers in secondary schools. A brief statement is made on the purpose and philosophy of dance education, and activities and instructional suggestions are presented for various dance forms: (1) group dance--folk/ethnic, square dance, and social dance; (2) aerobic dance; (3) jazz dance; (4) modern dance;…

Montgomery County Public Schools, Rockville, MD. Dept. of Instructional Planning and Development.

296

Secondary Education in Austria.  

ERIC Educational Resources Information Center

This booklet provides a brief description of secondary education in Austria. The publication is part of a series that seeks to make the public aware of the education systems and traditions in all signatory states to the European Cultural Convention and to outline the essential problems these systems presently are facing. This short booklet…

Aigner, Helmut

297

Aircraft Electric Secondary Power  

NASA Technical Reports Server (NTRS)

Technologies resulted to aircraft power systems and aircraft in which all secondary power is supplied electrically are discussed. A high-voltage dc power generating system for fighter aircraft, permanent magnet motors and generators for aircraft, lightweight transformers, and the installation of electric generators on turbine engines are among the topics discussed.

1983-01-01

298

Universal ripper miner  

DOEpatents

A universal ripper miner used to cut, collect and transfer material from an underground mine working face includes a cutter head that is vertically movable in an arcuate cutting cycle by means of drive members, such as hydraulically actuated pistons. The cutter head may support a circular cutter bit having a circular cutting edge that may be indexed to incrementally expose a fresh cutting edge. An automatic indexing system is disclosed wherein indexing occurs by means of a worm gear and indexing lever mechanism. The invention also contemplates a bi-directional bit holder enabling cutting to occur in both the upstroke and the downstroke cutting cycle. Another feature of the invention discloses multiple bits arranged in an in-line, radially staggered pattern, or a side-by-side pattern to increase the mining capacity in each cutting cycle. An on-board resharpening system is also disclosed for resharpening the cutting edge at the end of cutting stroke position. The aforementioned improvement features may be used either singly, or in any proposed combination with each other.

Morrell, Roger J. (Bloomington, MN); Larson, David A. (Minneapolis, MN)

1991-01-01

299

Secondary impact hazard assessment  

NASA Technical Reports Server (NTRS)

A series of light gas gun shots (4 to 7 km/sec) were performed with 5 mg nylon and aluminum projectiles to determine the size, mass, velocity, and spatial distribution of spall and ejecta from a number of graphite/epoxy targets. Similar determinations were also performed on a few aluminum targets. Target thickness and material were chosen to be representative of proposed Space Station structure. The data from these shots and other information were used to predict the hazard to Space Station elements from secondary particles resulting from impacts of micrometeoroids and orbital debris on the Space Station. This hazard was quantified as an additional flux over and above the primary micrometeoroid and orbital debris flux that must be considered in the design process. In order to simplify the calculations, eject and spall mass were assumed to scale directly with the energy of the projectile. Other scaling systems may be closer to reality. The secondary particles considered are only those particles that may impact other structure immediately after the primary impact. The addition to the orbital debris problem from these primary impacts was not addressed. Data from this study should be fed into the orbital debris model to see if Space Station secondaries make a significant contribution to orbital debris. The hazard to a Space Station element from secondary particles above and beyond the micrometeoroid and orbital debris hazard is categorized in terms of two factors: (1) the 'view factor' of the element to other Space Station structure or the geometry of placement of the element, and (2) the sensitivity to damage, stated in terms of energy. Several example cases were chosen, the Space Station module windows, windows of a Shuttle docked to the Space Station, the habitat module walls, and the photovoltaic solar cell arrays. For the examples chosen the secondary flux contributed no more than 10 percent to the total flux (primary and secondary) above a given calculated critical energy. A key assumption in these calculations is that above a certain critical energy, significant damage will be done. This is not true for all structures. Double-walled, bumpered structures are an example for which damage may be reduced as energy goes up. The critical energy assumption is probably conservative, however, in terms of secondary damage. To understand why the secondary impacts seem to, in general, contribute less than 10 percent of the flux above a given critical energy, consider the case of a meteoroid impact of a given energy on a fixed, large surface. This impact results in a variety of secondary particles, all of which have much less energy than the original impact. Conservation of energy prohibits any other situation. Thus if damage is linked to a critical energy of a particle, the primary flux will always deliver particles of much greater energy. Even if all the secondary particles impacted other Space Station structures, none would have a kinetic energy more than a fraction of the primary impact energy.

1986-01-01

300

Mineral induction by immobilized phosphoproteins  

NASA Technical Reports Server (NTRS)

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

Saito, T.; Arsenault, A. L.; Yamauchi, M.; Kuboki, Y.; Crenshaw, M. A.

1997-01-01

301

Secondary femoropopliteal reconstruction.  

PubMed Central

Retrospective analysis of the authors' experience with 109 primary femoropopliteal bypass vein grafts that failed allows description of three distinct modes of failure. Within 30 days of surgery, failure resulted primarily from technical or judgmental errors. The development of stenotic lesions within the vein graft caused a second group of failures during the first year after bypass. The third group most commonly failed due to progression of peripheral atherosclerosis a year or more following original bypass. No correlation was found, however, between the mode of failure and results of secondary femoropopliteal-tibial reconstruction, which yielded an overall 50% five-year cumulative limb salvage rate. The results indicate that this salvage rate can be anticipated regardless of the number of secondary operations required. The highest long-term patency rate was achieved when frequent postoperative follow-up examinations allowed recognition of graft failure prior to total occlusion. Under such circumstances a simple vein patch of stenotic lesions yielded an 85% five-year graft patency. Following actual thrombosis, however, the highest five-year patency rate was achieved when reconstruction was performed using a new vein graft; saphenous vein and arm vein were equally effective. When prosthetic material was used, no secondary graft remained patent beyond three years. Finally, when a proximal or distal portion of the original vein graft proved adequate in caliber following thrombectomy, it could be successfully incorporated in a secondary reconstruction with the expectation of a 50% five-year limb salvage rate. No statistically significant difference was found in salvage rates among each of the patient groups representing the three common modes of graft failure. This finding, coupled with an acceptable 2.5% operative mortality rate, provides justification for an aggressive approach toward secondary femoropopliteal reconstruction. Images Fig. 1a. Fig. 1c.

Whittemore, A D; Clowes, A W; Couch, N P; Mannick, J A

1981-01-01

302

The Trouble With Tailings: How Alteration Mineralogy can Hinder Quantitative Phase Analysis of Mineral Waste  

NASA Astrophysics Data System (ADS)

Quantitative phase analysis, using the Rietveld method and X-ray powder-diffraction data, has become a standard technique for analysis of mineral waste from mining operations. This method relies upon the availability of well defined crystal structures for all detectable mineral phases in a sample. An even more basic assumption, central to quantitative mineralogy, is that all significant mineral phases can be detected from X-ray diffraction data. This is not always the case, because X-ray amorphous and nanocrystalline mineral phases can develop within geological samples as a result of chemical weathering. The extent of mineral-water interaction to which mine tailings are exposed, during processing and storage, makes these materials particularly susceptible to weathering and alteration. We have used the Rietveld method and X-ray powder-diffraction data to quantify the uptake of atmospheric CO2 into secondary carbonate minerals at two operating mines: the Diavik Diamond Mine, Northwest Territories, Canada, and the Mount Keith Nickel Mine, Western Australia, Australia. At Diavik, nominally anhydrous minerals in kimberlitic mine tailings have been found to contain X-ray amorphous material and hydroxyl groups detectable by Raman spectroscopy. A series of weighed mixtures, prepared to simulate kimberlite mine tailings, has been used to assess the effects of X-ray amorphous material on quantitative phase analysis of Diavik tailings. At Mount Keith, hydrated sulphate minerals and halide minerals develop efflorescent crusts at the surface of the tailings storage facility. Hydrated sulphate minerals in these mine tailings commonly decompose to amorphous substances rather than dehydrating to produce minerals detectable from X-ray powder-diffraction patterns. Nanocrystalline and X-ray amorphous material in mine tailings can affect the accuracy of quantitative determinations of CO2 trapping and abundances of sulphur-bearing minerals associated with redox reactions. Here we assess the impact of amorphous material on quantitative X-ray diffraction results with particular reference to CO2 sequestration and suggest strategies for detection and analysis.

Wilson, S. A.; Mills, S. J.; Dipple, G. M.; Raudsepp, M.

2009-05-01

303

Chronic kidney disease: mineral and bone disorder in children.  

PubMed

Childhood and adolescence are crucial times for the development of a healthy skeletal and cardiovascular system. Disordered mineral and bone metabolism accompany chronic kidney disease (CKD) and present significant obstacles to optimal bone strength, final adult height, and cardiovascular health. Early increases in bone and plasma fibroblast growth factor 23 (FGF23) are associated with early defects in skeletal mineralization. Later in the course of CKD, secondary hyperparathyroidism--caused by a combination of declining calcitriol values and phosphate retention--results in high-turnover renal osteodystrophy whereas increased levels of both phosphate and FGF23 contribute to cardiovascular disease. Treatment of hyperphosphatemia and secondary hyperparathyroidism improves high-turnover bone disease but fails to correct defects in skeletal mineralization. Because overtreatment may result in adynamic bone disease, growth failure, hypercalcemia, and progression of cardiovascular calcifications, therapy therefore must be titrated carefully to maintain optimal serum biochemical parameters according to stage of CKD. Newer therapeutic agents and new treatment paradigms may suppress serum PTH levels effectively while limiting intestinal calcium absorption and skeletal FGF23 stimulation and may provide future therapeutic alternatives for children with CKD. PMID:23465503

Wesseling-Perry, Katherine; Salusky, Isidro B

2013-03-01

304

77 FR 56273 - Conflict Minerals  

Federal Register 2010, 2011, 2012, 2013

...tamper-proof format will add the necessary missing step to all the 3T minerals and smelter certification systems'') and Southern Africa Resource Watch (Apr. 4, 2012) (``SARW'') (stating that any scheme that ``essentially depends on...

2012-09-12

305

Electrochemical Study of Semisoluble Minerals.  

National Technical Information Service (NTIS)

The object of this work was to study basic electrochemical properties of semisoluble minerals such as apatite, calcite, and quartz, as a function of pretreatment and time of aging in aqueous solutions, and the solution temperature. Information on the basi...

P. Somasundaran

1974-01-01

306

Mining, Minerals and Sustainable Development  

NSDL National Science Digital Library

The Mining, Minerals and Sustainable Development Project (MMSD) is a completed, independent two-year project of research and consultation seeking to understand how the mining and minerals sector can contribute to the global transition to sustainable development. The final report, as well as various regional reports, timelines, and working papers, are available in English, Spanish, French, and Portuguese. Information on a wide spectrum of topics is available, including the following: armed conflict; artisanal and small-scale mining; biodiversity; current industry practice; corporate citizenship; finance dialogue; health and safety; human rights; indigenous peoples; information dialogue; large-volume waste; life-cycle assessment; managing mineral wealth; mine closure policy; minerals availability; planning for outcomes; public participation; and resettlement and displacement.

2007-06-25

307

Trace Mineral Losses in Sweat.  

National Technical Information Service (NTIS)

Copper, iron and zinc are nutritionally essential trace minerals that confer vital biological roles including the maintenance of cell structure and integrity, regulation of metabolism, immune function, oxygen transport, and muscle and central nervous syst...

J. P. McClung S. N. Cheuvront T. D. Chinevere

2007-01-01

308

Bone mineralization: Water brings order  

NASA Astrophysics Data System (ADS)

Measurements of the structure and organization of intact bone samples show that water plays a significant role in orienting bone apatite crystals, and that such ordering is mediated by an amorphous mineral coating layer.

Duer, Melinda; Veis, Arthur

2013-12-01

309

Preparation of Synthetic Standard Minerals.  

National Technical Information Service (NTIS)

A number of techniques for synthetic mineral preparations have been examined. These techniques include hot-pressing in graphite dies at moderate pressures, high-pressure, high-temperature synthesis in a piston and cylinder apparatus, isostatic pressing un...

C. C. Herrick S. J. Bustamante R. W. Charls R. E. Cowan E. A. Hakkila

1978-01-01

310

Microelectrophoresis of Selected Mineral Particles.  

National Technical Information Service (NTIS)

Particle mobilities of ilmenite, labradorite plagioclase, enstatite pyroxene, and olivine were measured with a Rank microelectrophoresis system to evaluate indicated mineral separability. Sodium bicarbonate buffer suspension media with and without additiv...

B. J. Herren R. W. Tipps K. D. Alexander

1982-01-01

311

Mineral Effects in Coal Conversion.  

National Technical Information Service (NTIS)

Recent literature pertaining to the chemical and catalytic activity of inherent mineral matter in coal conversion reactions is reviewed. The reactions are discussed in terms of increasing complexity: pyrolysis is considered first and this is followed by e...

R. M. Davidson

1983-01-01

312

Effective hydrodynamic boundary conditions for microtextured surfaces  

NASA Astrophysics Data System (ADS)

Understanding the influence of topographic heterogeneities on liquid flows has become an important issue with the development of microfluidic systems, and more generally for the manipulation of liquids at the small scale. Most studies of the boundary flow past such surfaces have concerned poorly wetting liquids for which the topography acts to generate superhydrophobic slip. Here we focus on topographically patterned but chemically homogeneous surfaces, and measure a drag force on a sphere approaching a plane decorated with lyophilic microscopic grooves. A significant decrease in the force compared with predicted even for a superhydrophobic surface is observed. To quantify the force we use the effective no-slip boundary condition, which is applied at the imaginary smooth homogeneous isotropic surface located at an intermediate position between the top and bottom of grooves. We relate its location to a surface topology by a simple, but accurate analytical formula. Since grooves represent the most anisotropic surface, our conclusions are valid for any texture, and suggest rules for the rational design of topographically patterned surfaces to generate desired drag.

Mongruel, Anne; Chastel, Thibault; Asmolov, Evgeny S.; Vinogradova, Olga I.

2013-01-01

313

Effective hydrodynamic boundary conditions for microtextured surfaces.  

PubMed

Understanding the influence of topographic heterogeneities on liquid flows has become an important issue with the development of microfluidic systems, and more generally for the manipulation of liquids at the small scale. Most studies of the boundary flow past such surfaces have concerned poorly wetting liquids for which the topography acts to generate superhydrophobic slip. Here we focus on topographically patterned but chemically homogeneous surfaces, and measure a drag force on a sphere approaching a plane decorated with lyophilic microscopic grooves. A significant decrease in the force compared with predicted even for a superhydrophobic surface is observed. To quantify the force we use the effective no-slip boundary condition, which is applied at the imaginary smooth homogeneous isotropic surface located at an intermediate position between the top and bottom of grooves. We relate its location to a surface topology by a simple, but accurate analytical formula. Since grooves represent the most anisotropic surface, our conclusions are valid for any texture, and suggest rules for the rational design of topographically patterned surfaces to generate desired drag. PMID:23410274

Mongruel, Anne; Chastel, Thibault; Asmolov, Evgeny S; Vinogradova, Olga I

2013-01-01

314

Enhanced radionuclide immobilization and flow path modifications by dissolution and secondary precipitates  

SciTech Connect

Caustic radioactive wastes that have leaked at Hanford Site (Richland, WA) induce mineral dissolution and subsequent secondary precipitation that influence the fate and transport of contaminants present in the waste solutions. The effects of secondary mineral precipitates, formed after contacting solids with simulated caustic wastes, on the flow path changes and radionuclide immobilization were investigated by reacting quartz, a mixture of quartz and biotite, and a Hanford sediment (Warden soil) with simulated caustic tank waste solution. Continuous Si dissolution and concomitant secondary mineral precipitation were the principal reactions observed in both batch and flow-through tests. Nitrate-cancrinite was the dominant secondary precipitate on mineral surfaces after 3 to 10 d reaction times in batch experiments. X-ray microtomography images of a reacted quartz column revealed that secondary precipitates cemented quartz grains together and modified pore geometry in the center of the column. Along the circumference of the packed column, however, quartz dissolution continuously occurred, suggesting that wastes that leaked from buried tanks in the past likely did not migrate vertically as modeled in risk assessments but rather the pathways likely changed to be dominantly horizontal upon precipitation of secondary precipitate phases in the Hanford vadose zone. Based on batch equilibrium sorption results on the reacted sediments, the dominant secondary precipitates (cancrinites) on the mineral surfaces enhanced the sorption capacity of typical Hanford sediment for radionuclides 129I(-I), 79Se(VI), 99Tc(VII), and 90Sr(II), all of which are of major concern at the Hanford Site.

Um, Wooyong; Serne, R JEFFREY.; Yabusaki, Steven B.; Owen, Antionette T.

2005-07-05

315

Secondary combined suicide pact.  

PubMed

This article reports a combined suicide pact, where in a young couple; a 26 year old male and a 20 year old female committed suicide by using two methods. The couple had resorted to hanging and self-immolation to prevent failure of single method alone. In secondary combined suicides, several other methods of suicide are tried after the first method chosen has failed. It is primary combined suicide only when two or more methods are used simultaneously. Both types of combined suicide by one individual is well reported in the literature whereas the same by two persons together is rare. In this report, the deceased were disappointed lovers, poor and the family members were against their marriage. The investigation of scene, methods employed to commit suicide, autopsy findings and the interview with their relatives altogether suggested that it was a secondary combined suicide pact. PMID:24661711

Jayanth, S H; Girish Chandra, Y P; Hugar, Basappa S; Kainoor, Sunilkumar

2014-03-01

316

Persulfate activation by subsurface minerals  

NASA Astrophysics Data System (ADS)

Persulfate dynamics in the presence of subsurface minerals was investigated as a basis for understanding persulfate activation for in situ chemical oxidation (ISCO). The mineral-mediated decomposition of persulfate and generation of oxidants and reductants was investigated with four iron and manganese oxides and two clay minerals at both low pH (< 7) and high pH (> 12). The manganese oxide birnessite was the most effective initiator of persulfate for degrading the oxidant probe nitrobenzene, indicating that oxidants are generated at both low and high pH regimes. The iron oxide goethite was the most effective mineral for degrading the reductant probe hexachloroethane. A natural soil and two soil fractions were used to confirm persulfate activation by synthetic minerals. The soil and soil fractions did not effectively promote the generation of oxidants or reductants. However, soil organic matter was found to promote reductant generation at high pH. The results of this research demonstrate that synthetic iron and manganese oxides can activate persulfate to generate reductants and oxidants; however, iron and manganese oxides in the natural soil studied do not show the same reactivity, most likely due to the lower masses of the metal oxides in the soil relative to the masses studied in isolated mineral systems.

Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

2010-06-01

317

Secondary Infobook Activities  

NSDL National Science Digital Library

This high school resource includes a set of student worksheets on energy, including topics like biomass, coal, geothermal energy, hydropower, natural gas, solar power, electricity and others. Answer keys are provided for all of the worksheets, and correlations to national science content standards are provided as well. This resource is intended to be used along with the secondary energy infobook, which can be found here.This material may be downloaded in PDF file format.

2012-10-10

318

Raynaud's phenomenon (secondary)  

PubMed Central

Introduction Raynaud’s phenomenon is episodic vasospasm of the peripheral vessels, causing pallor followed by cyanosis and redness with pain and sometimes paraesthesia, and, rarely, ulceration of the fingers and toes. It presents as episodic colour changes of the digits, usually in response to cold exposure or stress. The classic triphasic colour change is white (ischaemia), then blue (deoxygenation), then red (reperfusion). Raynaud’s phenomenon can be primary (idiopathic) or secondary to several different conditions and causes. This review deals with secondary Raynaud’s phenomenon. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of self-help measures for secondary Raynaud’s phenomenon? What are the effects of drug treatments for secondary Raynaud’s phenomenon? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 25 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: alpha-blockers; angiotensin-converting enzyme (ACE) inhibitors; angiotensin II receptor antagonists; antithrombotics/inhibitors of platelet aggregation; biofeedback; calcium channel blockers; endothelin-1 receptor antagonists; glyceryl trinitrate (transdermal); hand exercises; inositol nicotinate; moxisylyte; naftidrofuryl oxylate; phosphodiesterase inhibitors; prostaglandins (oral, intravenous); relaxation therapy; serotonin reuptake inhibitors (SRIs); smoking cessation; and warming hands and feet.

2008-01-01

319

Is the geological concept of clay minerals appropriate for soil science? A literature-based and philosophical analysis  

NASA Astrophysics Data System (ADS)

Data in the literature for soils that are dominated by each of the main types of clay minerals were examined and compared with those for reference clay minerals of the same types to determine the extent to which the nature and properties of clay-size minerals in soils could be explained by those of clay minerals with the same name from non-soil, ‘geological’ environments. Published information on soils from Australia, New Zealand and Iran was sourced for this study. The clay fractions of each of the soils are dominated by either one of the common phyllosilicates: kaolinite, halloysite, illite/mica, vermiculite, smectite, and palygorskite, or by the nanocrystalline mineral, allophane. Data for samples of kaolinite that had been extracted from soils from several countries (Australia, Thailand, Indonesia and Brazil) and purified before characterization have also been examined. In soils, each dominant clay mineral is generally associated with other materials, including iron oxides, other phyllosilicates and/or nanocrystalline minerals and organic matter. As the most studied example of an extracted phyllosilicate, kaolinite shows a wide range of properties in different soils, but a narrower range of properties within a particular locality. However, almost all of the soil kaolinites studied have larger specific surface areas and higher cation exchange capacities than reference kaolinites. The literature also reveals that, among phyllosilicates in soils, illites have a wide range of potassium contents, expandable minerals (vermiculites and smectites) may be interlayered by hydroxy-Al species particularly, and smectitic layers often occur interstratified with other layers, including those of illite, kaolinite and halloysite. The variability of soil phyllosilicates and their common association with other, often poorly crystallized but highly reactive minerals and compounds can be explained by their formation in the highly heterogeneous and dynamic soil environment. Phyllosilicates from non-soil or geological sources are poor models for the representation of secondary clay-size minerals in soils. In philosophical terms, the reduction of soil mineralogy to mineralogy as it is practiced within geology is misleading because of the differences between the minerals formed in soil and geological environments. In other words, clay minerals as they are defined as mineralogical entities for geology are of a different ‘kind’ to clay minerals in soils and cannot serve as ‘types’ or ‘stereotypes’ to enable explanation of the contribution of secondary clay-size minerals to soil properties or behavior. It is more useful to view clay minerals in soils as secondary inorganic compounds of clay-size than to follow their definition for non-soil purposes as plastic phyllosilicate minerals.

Churchman, G. Jock

320

Nitrification and nitrogen mineralization in a lowland rainforest succession in Costa Rica, Central America  

Microsoft Academic Search

Nitrogen availability is a critical component of productivity in successional lowland rainforests, and nitrogen losses from a given system may largely depend on rates of nitrification in soils of the system. Two hypotheses were tested in a study of a 6-point secondary rainforest sere in the coastal lowlands of Costa Rica: that nitrification and N mineralization change in a directed

G. Philip Robertson

1984-01-01

321

Accelerated Growth Plate Mineralization and Foreshortened Proximal Limb Bones in Fetuin-A Knockout Mice  

PubMed Central

The plasma protein fetuin-A/alpha2-HS-glycoprotein (genetic symbol Ahsg) is a systemic inhibitor of extraskeletal mineralization, which is best underscored by the excessive mineral deposition found in various tissues of fetuin-A deficient mice on the calcification-prone genetic background DBA/2. Fetuin-A is known to accumulate in the bone matrix thus an effect of fetuin-A on skeletal mineralization is expected. We examined the bones of fetuin-A deficient mice maintained on a C57BL/6 genetic background to avoid bone disease secondary to renal calcification. Here, we show that fetuin-A deficient mice display normal trabecular bone mass in the spine, but increased cortical thickness in the femur. Bone material properties, as well as mineral and collagen characteristics of cortical bone were unaffected by the absence of fetuin-A. In contrast, the long bones especially proximal limb bones were severely stunted in fetuin-A deficient mice compared to wildtype littermates, resulting in increased biomechanical stability of fetuin-A deficient femora in three-point-bending tests. Elevated backscattered electron signal intensities reflected an increased mineral content in the growth plates of fetuin-A deficient long bones, corroborating its physiological role as an inhibitor of excessive mineralization in the growth plate cartilage matrix - a site of vigorous physiological mineralization. We show that in the case of fetuin-A deficiency, active mineralization inhibition is a necessity for proper long bone growth.

Gupta, Himadri S.; Schafer, Cora; Krauss, Stefanie; Dunlop, John W. C.; Masic, Admir; Kerschnitzki, Michael; Zaslansky, Paul; Boesecke, Peter; Catala-Lehnen, Philip; Schinke, Thorsten; Fratzl, Peter; Jahnen-Dechent, Willi

2012-01-01

322

Defining reactive sites on hydrated mineral surfaces: Rhombohedral carbonate minerals  

NASA Astrophysics Data System (ADS)

Despite the success of surface complexation models (SCMs) to interpret the adsorptive properties of mineral surfaces, their construct is sometimes incompatible with fundamental chemical and/or physical constraints, and thus, casts doubts on the physical-chemical significance of the derived model parameters. In this paper, we address the definition of primary surface sites (i.e., adsorption units) at hydrated carbonate mineral surfaces and discuss its implications to the formulation and calibration of surface equilibria for these minerals. Given the abundance of experimental and theoretical information on the structural properties of the hydrated (10.4) cleavage calcite surface, this mineral was chosen for a detailed theoretical analysis of critical issues relevant to the definition of primary surface sites. Accordingly, a single, generic charge-neutral surface site ( tbnd CaCO 3·H 2O 0) is defined for this mineral whereupon mass-action expressions describing adsorption equilibria were formulated. The one-site scheme, analogous to previously postulated descriptions of metal oxide surfaces, allows for a simple, yet realistic, molecular representation of surface reactions and provides a generalized reference state suitable for the calculation of sorption equilibria for rhombohedral carbonate minerals via Law of Mass Action (LMA) and Gibbs Energy Minimization (GEM) approaches. The one-site scheme is extended to other rhombohedral carbonate minerals and tested against published experimental data for magnesite and dolomite in aqueous solutions. A simplified SCM based on this scheme can successfully reproduce surface charge, reasonably simulate the electrokinetic behavior of these minerals, and predict surface speciation agreeing with available spectroscopic data. According to this model, a truly amphoteric behavior is displayed by these surfaces across the pH scale but at circum-neutral pH (5.8-8.2) and relatively high ?CO 2 (?1 mM), proton/bicarbonate co-adsorption becomes important and leads to the formation of a charge-neutral H 2CO 3-like surface species which may largely account for the surface charge-buffering behavior and the relatively wide range of pH values of isoelectric points (pH iep) reported in the literature for these minerals.

Villegas-Jiménez, Adrián; Mucci, Alfonso; Pokrovsky, Oleg S.; Schott, Jacques

2009-08-01

323

Chemistry at the Organic-Mineral Interface Relevant to Titan  

NASA Astrophysics Data System (ADS)

The observation of rivers and lakes on Titan has generated considerable interest with regard to prebiotic chemistry, since these fluvial features provide a liquid medium for reactions and a transportation mechanism for catalytic mineral deposits left behind by meteorite impacts similar to the one that caused the Sinlap crater. Although numerous laboratory measurements and theoretical models have been used to study atmospheric chemistry applicable to Titan's potential astrobiology, few experiments have been performed to understand gas-/liquid-surface reactions. We are exploring heterogeneous chemistry relevant to Titan using low energy electrons (5-50 eV) as an analog of the incident cosmic rays and secondary electrons they generate. Amorphous alkane/acetylene ices have been deposited on mineral and carbon substrates to simulate lake environments. In some cases, small amounts of amorphous water ice have been deposited at the organic-mineral boundary to model the interface of the hydrocarbon "soil” and the underlying water-ice "bedrock” of Titan. Preliminary results suggest that protonation occurs readily even at the low temperatures observed on Titan's surface ( 100 K). These experiments are some of the first aimed at understanding chemistry at the organic-mineral interface under conditions relevant to Titan, in particular at the edges of hydrocarbon lakes. This work has been performed as part of the NASA Astrobiology Institute "Titan as a Prebiotic System” at the Jet Propulsion Laboratory.

Abbott-Lyon, Heather; Dawley, M.; McLain, J.; Grieves, G.; Orlando, T.

2010-10-01

324

Secondary navigation in software wizards  

Microsoft Academic Search

The authors conducted a study of three approaches to secondary navigation in software wizards. Secondary navigation refers to user interface navigation controls that are in addition to the standard \\

Mary Burton; Daina Pupons Wickham; Lori Phelps; Kelly Spain; Janna Crews; Nicki Rich

1999-01-01

325

Calculating a Mineral's Density  

NSDL National Science Digital Library

Students will use the Density=Mass/Volume formula to calculate the density of an unknown mineral. By using water displacement and a triple beam balance students will collect measurements of volume and mass for an unknown mineral. With this data, they will calculate the mineral's density then identify the mineral based on calculated density.

Distelhurst, Andrea

2011-10-05

326

Minerals Arranged by the New Dana Classification  

NSDL National Science Digital Library

This directory provides a listing of mineral species based on Dana's New Mineralogy, in which a number is assigned to each class based on a combination of chemistry and crystal structure. Clicking on each class heading provides access to a list of each mineral that conforms to that class. Each mineral name is a link to additional information on the mineral.

Barthelmy, David

327

Understanding mineral dusts from the Middle East  

NASA Astrophysics Data System (ADS)

The purpose of the program was to provide scientifically founded information on the chemical and physical properties of airborne mineral dust collected during a period of approximately one year, largely in 2006, at Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (Northern, Central, Coastal, and Southern regions). To fully understand mineral dusts, their chemical and physical properties as well as mineralogical interrelationships were accurately established. Three collocated low volume particulate samplers, one each for the total suspended (TSP), less than 10 ?m in aerodynamic diameter (PM10), and less than 2.5 ?m in aerodynamic diameter (PM2.5) particulate matter were deployed at each of the 15 sites, operating on a "1 in 6 day" sampling schedule. A total of 3,136 filter samples were collected on a 1-in-6 day schedule, along with one-time bulk soil samples, at each of the 15 sites. Sample media included Teflon® membrane and quartz fiber filters for chemical analysis (71 species), and Nuclepore® filters for individual particle analysis by Scanning Electron Microscopy (SEM). The provisional study of the data revealed three broad air pollution sources: geological dust, smoke from burn pits, and until now unidentified lead-zinc smelters and battery-processing facilities. SEM results and secondary electron imagery show that quartz and other silicate minerals and, to a lesser extent, dolomite and calcite particles are coated by a thin Si-Al-Mg layer, probably the clay minerals palygorskite and/or montmorillonite/illite. Positive Matrix Factorization (PMF) was performed on aerosol samples collected at six military sites in Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, and Al Asad). PMF results reflect chemical differences amongst sources impacting at individual sites, further complicated by the regional geomorphology and meteorology. Sampling sites are seldom impacted by one source at a time. Also, dust palls are continually being modified by added dust from soils across which they migrate, and by particle segregation in the dust plume followed by precipitation of the coarser particles. PMF was applied separately to two ambient data sets collected in Iraq in 2006, the one on Teflon membrane filters and the other on quartz fiber. Each of the filter types were previously analyzed for different chemical species: Teflon membrane for elements, by XRF and ICP-MS, while quartz fiber filters were analyzed for ions and carbon. A set of 392 Teflon filter samples analyzed for 25 elemental species was modeled by PMF. A five factor solution identified three soil factors, a silicate soil, limestone soil, and a gypsum soil, as well as a salt factor and an anthropogenic metal factor. Similarly, a set of 362 quartz filter samples analyzed for 10 selected chemical species was modeled by PMF. A five factor solution provided a limestone-gypsum soil, diesel combustion, secondary ammonium sulfate, salt and agricultural-burnpit combustion source type.

Engelbrecht, J. P.; McDonald, E.; Gillies, J. A.; Jayanty, J.; Casuccio, G.; Gertler, A.

2012-12-01

328

Petrography, mineral chemistry, and petrogenesis of Antarctic Shergottite LEW88516  

NASA Astrophysics Data System (ADS)

LEW88516 (LEW), like its near-twin ALH77005 (ALH), is a maskelynite-bearing harzburgite and a member of the SNC family of achondrites. LEW is texturally heterogenous, exhibiting both poikilitic (pyroxene oikocrysts enclosing subhedral olivine and euhedral chromite) and non-poikilitic (cumulus framework of olivine and minor pyroxene, with interstitial maskelynite and secondary minerals) textures. Pyroxenes in LEW appear to be slightly more iron-rich and more varied in composition than those in ALH. LEW olivines have distinctly higher Fe contents; most of the olivine grains in LEW have compositions more iron-rich than any ALH olivine observed. LEW olivine in non-poikilitic areas is substantially more iron-rich than olivine armored by pyroxene. Trace element and minor element patterns of LEW and ALH minerals are essentially identical and are consistent with closed-system, large-volume crystallization of the major phases, followed by development of later phases after assembly of the crystal pile.

Harvey, R. P.; Wadhwa, M.; McSween, H. Y., Jr.; Crozaz, G.

1993-10-01

329

Secondary air feed control device  

Microsoft Academic Search

A secondary air feed control device for an internal combustion engine having in its exhaust system a three way catalytic converter and an oxygen concentration detector is disclosed. This detector provides a signal indicating that the total air-fuel ratio is smaller than the stoichiometric air-fuel ratio. The secondary air feed control device comprises a valve port through which the secondary

1979-01-01

330

Technical Subjects in Secondary Schools  

ERIC Educational Resources Information Center

Purpose: This paper aims to examine technical education in various types of secondary schools, and suggests three levels of technical courses to be taught in secondary schools. Design/methodology/approach: The paper discusses the differences between technical schools and colleges, and vocational technical courses taught in "academic" secondary

Howard, A. E.

2008-01-01

331

Seafloor bioalteration of sulfide minerals: results from in situ incubation studies  

NASA Astrophysics Data System (ADS)

We present results of incubation studies conducted at low temperatures (˜4°C) in the vicinity of a seafloor hydrothermal vent system. We reacted Fe-, S-, Cu-, and Zn-bearing minerals including pyrite, marcasite, chalcopyrite, sphalerite, elemental sulfur, and a portion of a natural chimney sulfide structure for 2 months at the Main Endeavour Segment of the Juan de Fuca Ridge in the Pacific Ocean. Our study utilizes Fluorescent In Situ Hybridizations (FISH), Scanning and Transmission Electron Microscopy (SEM, TEM), and light microscopic analysis. The surfaces of these minerals are solely colonized by Bacteria and not by Archaea. Colonization densities vary over an order of magnitude with the following sequence: elemental sulfur > chimney sulfide > marcasite > pyrite > sphalerite > chalcopyrite, and correspond well with the abiotic oxidation kinetics of these materials, excepting elemental sulfur, which is both the least reactive to oxidizing species and the most heavily colonized. Colonization densities also correspond with apparent degree of reaction (dissolution pitting + accumulation of secondary alteration products). Heavy accumulations of secondary Fe oxides on Fe-bearing minerals, most notably on the chimney sulfide, form in situ as the result of mineral dissolution and the activity of neutrophilic Fe-oxidizing bacteria. Results suggest that mineral-oxidizing bacteria play a prominent role in weathering of seafloor sulfide deposits, and that microbial utilization of mineral substrates contributes to biomass production in seafloor hydrothermal environments.

Edwards, Katrina J.; McCollom, Thomas M.; Konishi, Hiromi; Buseck, Peter R.

2003-08-01

332

25 CFR 225.33 - Assignment of minerals agreements.  

Code of Federal Regulations, 2011 CFR

...33 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS OIL AND GAS, GEOTHERMAL, AND SOLID MINERALS AGREEMENTS Minerals Agreements § 225.33 Assignment of minerals agreements. An assignment of a minerals...

2014-04-01

333

25 CFR 225.22 - Approval of minerals agreements.  

Code of Federal Regulations, 2012 CFR

...22 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS OIL AND GAS, GEOTHERMAL, AND SOLID MINERALS AGREEMENTS Minerals Agreements § 225.22 Approval of minerals agreements. (a) A minerals agreement...

2014-04-01

334

Formation and Reactivity of Biogenic Iron Minerals  

SciTech Connect

Dissimilatory iron-reducing bacteria (DIRB) play an important role in regulating the aqueous geochemistry of iron and other metals in anaerobic, non-sulfidogenic groundwater environments; however, little work has directly assessed the cell surface electrochemistry of DIRB, or the nature of the interfacial environment around individual cells. The electrochemical properties of particulate solids are often inferred from titrations in which net surface charge is determined, assuming electroneutrality, as the difference between known added amounts of acid and base and measured proton concentration. The resultant titration curve can then be fit to a speciation model for the system to determine pKa values and site densities of reactive surface sites. Moreover, with the development of non-contact electrostatic force microscopy (EFM), it is now possible to directly inspect and quantify charge development on surfaces. A combination of acid-base titrations and EFM are being used to assess the electrochemical surface properties of the groundwater DIRB, Shewanella putrefaciens. The pKa spectra and EFM data show together that a high degree of electrochemical heterogeneity exists within the cell wall and at the cell surface of S. putrefaciens. Recognition of variations in the nature and spatial distribution of reactive sites that contribute to charge development on these bacteria implies further that the cell surface of these Fe(III)-reducing bacteria functions as a highly differentiated interfacial system capable of supporting multiple intermolecular interactions with both solutes and solids. These include surface complexation reactions involving dissolved metals, as well as adherence to mineral substrates such as hydrous ferric oxide through longer-range electrostatic interactions, and surface precipitation of secondary reduced-iron minerals.

Ferris, F. Grant

2002-06-01

335

Secondary "hypnic headache".  

PubMed

Hypnic headache is a rare form of primary headache with attacks occurring exclusively with sleep. As it is typical of the elderly, a wide range of alternative diagnosis must be considered. We present a case report of a 54-year-old woman with unsuspected secondary hypnic headache that was relieved by anti-hypertensive therapy. We reviewed the literature to evaluate the usual diagnostic workup performed in hypnic headache patients. We suggest that 24 h ambulatory blood pressure monitoring may be included in the evaluation of nocturnal headache complaints especially in the elderly, in whom essential hypertension is a very frequent comorbidity. PMID:17404778

Gil-Gouveia, Raquel; Goadsby, Peter J

2007-05-01

336

Traditional Methods for Mineral Analysis  

NASA Astrophysics Data System (ADS)

This chapter describes traditional methods for analysis of minerals involving titrimetric and colorimetric procedures, and the use of ion selective electrodes. Other traditional methods of mineral analysis include gravimetric titration (i.e., insoluble forms of minerals are precipitated, rinse, dried, and weighed) and redox reactions (i.e., mineral is part of an oxidation-reduction reaction, and product is quantitated). However, these latter two methods will not be covered because they currently are used little in the food industry. The traditional methods that will be described have maintained widespread usage in the food industry despite the development of more modern instrumentation such as atomic absorption spectroscopy and inductively coupled plasma-atomic emission spectroscopy (Chap. 24). Traditional methods generally require chemicals and equipment that are routinely available in an analytical laboratory and are within the experience of most laboratory technicians. Additionally, traditional methods often form the basis for rapid analysis kits (e.g., Quantab®; for salt determination) that are increasingly in demand. Procedures for analysis of minerals of major nutritional or food processing concern are used for illustrative purposes. For additional examples of traditional methods refer to references (1-6). Slight modifications of these traditional methods are often needed for specific foodstuffs to minimize interferences or to be in the range of analytical performance. For analytical requirements for specific foods see the Official Methods of Analysis of AOAC International (5) and related official methods (6).

Ward, Robert E.; Carpenter, Charles E.

337

Fe-Ni metal and sulfide minerals in CM chondrites: An indicator for thermal history  

USGS Publications Warehouse

CM chondrites were subjected to aqueous alteration and, in some cases, to secondary metamorphic heating. The effects of these processes vary widely, and have mainly been documented in silicate phases. Herein, we report the characteristic features of Fe-Ni metal and sulfide phases in 13 CM and 2 CM-related chondrites to explore the thermal history of these chondrites. The texture and compositional distribution of the metal in CM are different from those in unequilibrated ordinary and CO chondrites, but most have similarities to those in highly primitive chondrites, such as CH, CR, and Acfer 094. We classified the CM samples into three categories based on metal composition and sulfide texture. Fe-Ni metal in category A is kamacite to martensite. Category B is characterized by pyrrhotite grains always containing blebs or lamellae of pentlandite. Opaque mineral assemblages of category C are typically kamacite, Ni-Co-rich metal, and pyrrhotite. These categories are closely related to the degree of secondary heating and are not related to degree of the aqueous alteration. The characteristic features of the opaque minerals can be explained by secondary heating processes after aqueous alteration. Category A CM chondrites are unheated, whereas those in category B experienced small degrees of secondary heating. CMs in category C were subjected to the most severe secondary heating process. Thus, opaque minerals can provide constraints on the thermal history for CM chondrites. ?? The Meteoritical Society, 2011.

Kimura, M.; Grossman, J. N.; Weisberg, M. K.

2011-01-01

338

The composition of mineral inclusions in the olivines of pallasites  

NASA Astrophysics Data System (ADS)

An examination of a number of pallasite meteorites revealed the composition of primary and secondary solid inclusions as well as the composition of gaseous inclusions in the olivines. It is shown that the gaseous inclusions in the olivine of the Bragin meteorite consist of nitrogen and rare gases as well as carbon dioxide and hydrogen; the absence of oxygen is evidence of reduction during crystallization. Both one-phase and two-phase inclusions were disclosed; the two-phase inclusions consist of both solid and gaseous components. Phosphate minerals reveal traces of the spontaneous fission of uranium, plutonium-244, and possibly an unknown superheavy element.

Kolomenskii, V. D.; Dolivo-Dobrovolskaia, G. I.; Perelygin, V. P.

339

Mineral Status of Myocardial Sarcocystosis  

PubMed Central

Background The role of minerals on parasite persistency and the interaction between minerals and animal responses to the parasite infestation is not clear. For these reasons, the present research was aimed to compare copper, zinc and iron status in sheep with parasitic myocarditis and healthy ones in 2009. Methods Blood and heart tissue samples were collected from 145 slaughtered sheep and histopathological findings were confirmed as myocardial sarcocystosis in 27 cases. Serum and tissue mineral level were determined by atomic absorption spectroscopy. Data were analyzed by Sigmastat program, using One Way Analysis of Variance (ANOVA) at the level of P<0.05. Results Myocardial sarcocystosis significantly increase myocardial concentration of Cu, Zn and Fe (P<0.05). Conclusion These findings may explain the role of copper, zinc and iron in parasite persistency and may discuss the pathogenesis of sarcocystosis, which relates to evocate mentioned micronutrient to cardiac muscle.

Kojouri, GA; Aghajani, E; Jahanabadi, S; Kojouri, A

2011-01-01

340

Refractory minerals in interplanetary dust  

NASA Technical Reports Server (NTRS)

A newly studied interplanetary dust particle contains a unique set of minerals that closely resembles assemblages in the refractory, calcium- and aluminum-rich inclusions in carbonaceous chondrite meteorites. The set of minerals includes diopside, magnesium-aluminum spinel, anorthite, perovskite, and fassaite. Only fassaite has previously been identified in interplanetary dust particles. Diopside and spinel occur in complex symplectic intergrowths that may have formed by a reaction between condensed melilite and the solar nebula gas. The particle represents a new link between interplanetary dust particles and carbonaceous chondrites; however, the compositions of its two most abundant refractory phases, diopside and spinel, differ in detail from corresponding minerals in calcium- and aluminum-rich inclusions.

Christoffersen, Roy; Buseck, Peter R.

1986-01-01

341

Refractory minerals in interplanetary dust.  

PubMed

A newly studied interplanetary dust particle contains a unique set of minerals that closely resembles assemblages in the refractory, calcium- and aluminum-rich inclusions in carbonaceous chondrite meteorites. The set of minerals includes diopside, magnesium- aluminum spinel, anorthite, perovskite, and fassaite. Only fassaite has previously been identified in interplanetary dust particles. Diopside and spinel occur in complex symplectic intergrowths that may have formed by a reaction between condensed melilite and the solar nebula gas. The particle represents a new link between interplanetary dust particles and carbonaceous chondrites; however, the compositions of its two most abundant refractory phases, diopside and spinel, differ in detail from corresponding minerals in calcium- and aluminum-rich inclusions. PMID:17835566

Christoffersen, R; Buseck, P R

1986-10-31

342

Uranium mineralization in the two mica granite of gabal Ribdab area, South Eastern Desert, Egypt.  

PubMed

Among the different rock units in the Gabal Ribdab area, the two-mica leucogranite and muscovite pegmatitic granite are the most favourable host rocks for uranium and thorium mineralization. The muscovite pegmatitic granite shows evidence of post-magmatic alteration, e.g. Na- and K-metasomatism, whereas the two-mica leucogranite could be regarded as being fresh. The spectrometric survey revealed the presence of three enriched zones with a maximum eU content of 140 ppm and the maximum eTh is 36 ppm. Uranophane, zippeite and becquerelite are the most abundant uranium minerals. The origin of these secondary minerals is mainly related to alteration of primary minerals by the action of oxidizing fluids, mobilization of uranium and then redeposition in other forms. Redistribution by circulating meteoric waters might have taken place. PMID:11761111

Ibrahim, M E; Saleh, G M; Abd El-Naby, H H

2001-12-01

343

Quantifying elemental compositions of primary minerals from granitic rocks and saprolite within the Santa Catalina Mountain Critical Zone Observatory  

NASA Astrophysics Data System (ADS)

Granitic terrain comprises a significant area of the earth's land surface (>15%). Quantifying weathering processes involved in the transformation of granitic rock to saprolite and soil is central to understanding landscape evolution in these systems. The quantification of primary mineral composition is important for assessing subsequent mineral transformations and soil production. This study focuses on coupling detailed analysis of primary mineral composition to soil development across an array of field sites sampled from the Santa Catalina Mountain Critical Zone observatory (SCM-CZO) environmental gradient. The gradient spans substantial climate-driven shifts in vegetation, ranging from desert scrub to mixed conifer forests. The parent material is a combination of Precambrian and Tertiary aged granites and quartz diorite. Primary mineral type and composition are known to vary among the various aged granitic materials and this variability is hypothesized to manifest as significant variation in regolith forming processes across the SCM-CZO. To address this variability, the mineral composition and mineral formulae of rock and saprolite samples were determined by electron microprobe chemical analyses. The rocks were pre-dominantly quartz, biotite, muscovite, orthoclase and calcium/sodium-rich plagioclase feldspars. Trace minerals observed in the samples included sphene, rutile, zircon, garnet, ilmenite, and apatite. Mineral formulae from electron microprobe analyses were combined with quantitative x-ray diffraction (QXRD) and x-ray fluorescence (XRF) data to quantify both primary and secondary mineralogical components in soil profiles from each of the field sites. Further, electron microprobe analyses of <2mm mixed conifer saprolite revealed weathered plagioclase grains coated with clay-sized particles enriched in silica and aluminum (~25% and 15%, respectively), suggesting kaolin as the secondary phase. The coatings were interspersed within each plagioclase grain, a strong indicator that the grain was transforming in situ to secondary weathering products. Other feldspar minerals in the sample appeared relatively un-weathered and were contained within perthite structural units where the plagioclase minerals were preserved as intergrowths of the orthoclase groundmasses. These results suggest differential plagioclase weathering pathways that may have resulted from variations in physical erosion rates or different geologic configurations of the feldspar minerals. Secondary mineral assemblages of the sample included kaolinite, dehydrated halloysite, illite, vermiculite, chlorite and gibbsite, indicating chemical alteration of both micas and feldspars. Current research is focused on additional electron microprobe analyses of surface and saprolite samples from other field areas along the gradient. The electron microprobe data aided in the constraint of chemical weathering processes as related to primary mineral composition.

Lybrand, R. A.; Rasmussen, C.

2011-12-01

344

Bone Mineral Density and Logarithms  

NSDL National Science Digital Library

Students examine an image produced by a cabinet x-ray system to determine if it is a quality bone mineral density image. Students write in their journals about what they need to know to be able to make this judgment. Students learn about what bone mineral density is, how a BMD image can be obtained, and how it is related to the field of x-ray. Students examine the process used to obtain a BMD image and how this process is related to mathematics, primarily through logarithmic functions. Students study the relationship between logarithms and exponents, the properties of logarithms, common and natural logarithms, solving exponential equations, and Beer's Law.

Vu Bioengineering Ret Program

345

43 CFR 3000.8 - Management of Federal minerals from reserved mineral estates.  

Code of Federal Regulations, 2010 CFR

...prospect for, mine and remove the minerals under applicable law and regulations...management of the use of such minerals shall be accomplished under the regulations of Groups 3000 and 3100 of this title. Such mineral estates include, but...

2009-10-01

346

43 CFR 3000.8 - Management of Federal minerals from reserved mineral estates.  

Code of Federal Regulations, 2010 CFR

...prospect for, mine and remove the minerals under applicable law and regulations...management of the use of such minerals shall be accomplished under the regulations of Groups 3000 and 3100 of this title. Such mineral estates include, but...

2010-10-01

347

Organo-mineral complexation alters carbon and nitrogen cycling in stream microbial assemblages  

NASA Astrophysics Data System (ADS)

Inland waters are of global biogeochemical importance receiving carbon inputs of ~ 4.8 Pg C y-1. Of this 12 % is buried, 18 % transported to the oceans, and 70 % supports aquatic secondary production. However, the mechanisms that determine the fate of organic matter (OM) in these systems are poorly defined. One important aspect is the formation of organo-mineral complexes in aquatic systems and their potential as a route for OM transport and burial vs. microbial utilization as organic carbon (C) and nitrogen (N) sources. Organo-mineral particles form by sorption of dissolved OM to freshly eroded mineral surfaces and may contribute to ecosystem-scale particulate OM fluxes. We tested the availability of mineral-sorbed OM as a C & N source for streamwater microbial assemblages and streambed biofilms. Organo-mineral particles were constructed in vitro by sorption of 13C:15N-labelled amino acids to hydrated kaolin particles, and microbial degradation of these particles compared with equivalent doses of 13C:15N-labelled free amino acids. Experiments were conducted in 120 ml mesocosms over 7 days using biofilms and streamwater sampled from the Oberer Seebach stream (Austria), tracing assimilation and mineralization of 13C and 15N labels from mineral-sorbed and dissolved amino acids. Here we present data on the effects of organo-mineral sorption upon amino acid mineralization and its C:N stoichiometry. Organo-mineral sorption had a significant effect upon microbial activity, restricting C and N mineralization by both the biofilm and streamwater treatments. Distinct differences in community response were observed, with both dissolved and mineral-stabilized amino acids playing an enhanced role in the metabolism of the streamwater microbial community. Mineral-sorption of amino acids differentially affected C & N mineralization and reduced the C:N ratio of the dissolved amino acid pool. The present study demonstrates that organo-mineral complexes restrict microbial degradation of OM and may, consequently, alter the carbon and nitrogen cycling dynamics within aquatic ecosystems.

Hunter, William Ross; Wanek, Wolfgang; Prommer, Judith; Mooshammer, Maria; Battin, Tom

2014-05-01

348

Characterization of minerals and organic phosphorus species in marine sediments using soft X-ray fluorescence spectromicroscopy  

Microsoft Academic Search

Phosphorus Near Edge X-ray Fluorescence Spectroscopy (P-NEXFS) data were collected on phosphorus containing phases including organic and inorganic compounds and minerals. Although phases containing P in the plus five oxidation state P(V) in a tetrahedral PO4 structure have similar primary fluorescence peak positions, the size, shape, and positions of secondary spectral features are diagnostic for different compounds and minerals. In

Jay A. Brandes; Ellery Ingall; David Paterson

2007-01-01

349

Mineral arsenicals in traditional medicines: Orpiment, realgar, and arsenolite  

PubMed Central

Mineral arsenicals have long been used in traditional medicines for various diseases, yet arsenic can be highly toxic and carcinogenic. Arsenic in traditional medicines typically comes from deliberate addition for therapeutic purposes, mainly in the form of mineral arsenicals including orpiment (As2S3), realgar (As4S4), and arsenolite (contains arsenic trioxide, As2O3). Inorganic arsenic is now accepted in Western medicine as a first line chemotherapeutic agent against certain hematopoietic cancers. This minireview analyzes the pharmacology and toxicology of these arsenicals used in traditional medicines. Orpiment and realgar are less soluble and poorly absorbed from the gastrointestinal tract, while the bioavailability of arsenic trioxide is similar to inorganic arsenic salts like sodium arsenite. Pharmacological studies show that arsenic trioxide and realgar are effective against certain malignancies. Orpiment and realgar are used externally for various skin diseases. Realgar is frequently included as an ingredient in oral traditional remedies for its antipyretic, antiinflammatory, antiulcer, anticonvulsive and anti-schistosmiasis actions, but the pharmacological basis for this inclusion still remains to be fully justified. Toxicological studies show that cardiovascular toxicity is the major concern for arsenic trioxide, and the gastrointestinal and dermal adverse effects may occur after prolonged use of mineral arsenicals. Little is known about possible secondary cancers resulting from the long-term use of any of these arsenicals. Similar to the safety evaluation of seafood arsenicals, total arsenic content alone appears to be insufficient for mineral arsenical safety evaluation. Arsenic speciation, bioavailability, and toxicity/benefit should be considered in evaluation of mineral arsenical-containing traditional medicines.

Liu, Jie; Lu, Yuanfu; Wu, Qin; Goyer, Robert A; Waalkes, Michael P.

2009-01-01

350

Plants and microorganisms as drivers of mineral weathering  

NASA Astrophysics Data System (ADS)

Plants and microorganisms play important role in mineral weathering and soil formation modifying their environment to make it more hospitable for life. This presentation summarizes several collaborative studies that focused on understanding how interactions between plants and microorganisms, where plants provide the energy through photosynthesis, drive mineral weathering and result in soil formation. Plants influence weathering through multiple mechanisms that have been previously established, such as increase in CO2 concentration in the soil through root respiration and degradation of plant residues and exudates by heterotrophic microorganisms, release of organic acids that promote mineral dissolution, removal of weathering products from soil solution through uptake, and water redistribution. Weathering processes result in nutrient release that satisfies immediate needs of the plants and microorganisms, as well as precipitation of secondary phases, that provide surfaces for retention of nutrients and organic carbon accumulation. What makes understanding contribution of plants and microorganisms, such as bacteria and fungi, to mineral weathering challenging is the fact that they closely interact, enhancing and amplifying each other's contribution. In order to address multiple processes that contribute to and result from biological weathering a combination of chemical, biological, mineralogical, and computational techniques and methodologies is needed. This complex array of methodologies includes bulk techniques, such as determination of total dissolved organic and inorganic carbon and nitrogen, ion chromatography and high performance liquid chromatography to characterize amount and composition of exuded organic acids, inductively coupled plasma mass spectrometry to determine concentrations of lithogenic elements in solution, X-ray diffraction to characterize changes in mineral composition of the material, DNA extraction to characterize community structure, as well as microscopic techniques. These techniques in combination with numerical geochemical modeling are being employed to improve our understanding of biological weathering.

Dontsova, K.; Chorover, J.; Maier, R.; Hunt, E.; Zaharescu, D. G.

2011-12-01

351

Magnesium isotope fractionation during extreme weathering of basalt controlled by clay mineral formation  

NASA Astrophysics Data System (ADS)

Chemical weathering of silicate rocks is considered to be one of the major processes that affects the chemical composition of the continental crust and the carbon cycle. More recently, application of Mg isotopes as geochemical proxy of chemical weathering has attracted considerable attention. Primary mineral dissolution and secondary mineral formation are considered as the two principal processes controlling Mg isotope fractionation during chemical weathering, but the impact of the mineralogy of secondary phases on Mg isotope fractionation is still unclear. To better understand the role of secondary mineral formation in the fractionation of Mg isotopes during extreme weathering, we have determined the chemical compositions and Mg isotopic ratios of a set of well-characterized saprolites developed on Neogene basalt in Hainan island, south China. The weathering products are dominated by kaolin-group minerals and Al- and Fe-oxy-hydroxides and the primary minerals of the parent rocks are almost absent due to the extreme weathering. Relative to the fresh basalts, magnesium is completely depleted in the saprolites, the values of percentage change of Mg ratios to Th relative to parent rock (?Th,Mg) range between -92.91% and -99.10%. The ?26Mg of saprolites vary from -0.51 to +0.34 % relative to the reference material DSM3. The unaltered basalt has a ?26Mg isotopic composition of -0.33%, similar to fresh oceanic basalt samples. Saprolite at the top has the lowest ?26Mg value of -0.51% and the heaviest ?26Mg value occur at 3.65m depth, where most mobile elements (eg. Al, Mg, Mn) are enriched. Except three samples at the upper section of the profile, the ?26Mg value of the fresh basalt is lighter than that of the overlying saprolites. These observations are consistent with release of light Mg to the hydrosphere and concentration of isotopically heavier Mg in the weathered products. A linear correlation between ?26Mg and the abundance of clay minerals is observed in this weathering profile. ?26Mg values negatively correlate with kaolinite modal abundance and positively correlates with halloysite modal abundance. These results suggest that the formation of halloysite during basalt weathering preferentially incorporates heavy Mg isotopes whereas formation of kaolinite preferentially incorporates light Mg isotopes. Our results highlight that the formation of secondary clay minerals controls Mg isotope fractionation during weathering, and this fractionation is highly dependent on clay mineral type and the Mg crystalline site in the minerals.

Huang, K.; Teng, F.; Ma, J.; Wei, G.; Bao, Z.

2011-12-01

352

Sulfate minerals and organic compounds on Mars  

NASA Astrophysics Data System (ADS)

Strong evidence for evaporitic sulfate minerals such as gypsum and jarosite has recently been found on Mars. Although organic molecules are often codeposited with terrestrial evaporitic minerals, there have been no systematic investigations of organic components in sulfate minerals. We report here the detection of organic material, including amino acids and their amine degradation products, in ancient terrestrial sulfate minerals. Amino acids and amines appear to be preserved for geologically long periods in sulfate mineral matrices. This suggests that sulfate minerals should be prime targets in the search for organic compounds, including those of biological origin, on Mars.

Aubrey, Andrew; Cleaves, H. James; Chalmers, John H.; Skelley, Alison M.; Mathies, Richard A.; Grunthaner, Frank J.; Ehrenfreund, Pascale; Bada, Jeffrey L.

2006-05-01

353

Mineral content of quail embryos cultured in mineral-rich and mineral-free conditions.  

PubMed

Japanese quail embryos were cultured in mineral rich (MR) using chickens egg shell and mineral-free (MF) using Saran Wrap cultures after 2.5 days of normal incubation. In the MR culture, 82% of embryos survived beyond 14.5 days of incubation and 3 embryos out of 93 (3%) hatched. In the MF culture, 80% survived beyond 9.5 days and 59% beyond 14.5 days. Mineral content (Ca, Mg, K, and Na) of the embryos and of the residual matter within the egg (remaining egg contents excluding the embryo, shell, and shell membrane) were analyzed at 7 to 15 days of incubation. Calcium content of the embryos increased gradually between 9 and 11 days and showed a rapid increase after 11 days in both normal incubation (control) and MR culture. Changes in mineral levels of the embryos plus residual matter within the egg were as follows. Calcium content of the controls increased gradually between 9 and 11 days and showed a rapid increase after 11 days. In MR cultures, Ca increased between 10 and 12 days and showed a rapid increase after 12 days. Magnesium content increased rapidly after 13 days in controls and showed a small increase after 13 days in MR cultures. Potassium and Na content remained constant in both controls and MR cultures. In MF cultures, content of the four minerals remained constant throughout the culture period. Mineral levels of Japanese quail and chicken eggs were compared before and after normal incubation. It was found that 81.5% of Ca and 30.8% of Mg assimilated by newly hatched quail chicks were derived from the egg shell during incubation and 84.2% of Ca and 23.5% of Mg in the chicken. PMID:6701139

Ono, T; Wakasugi, N

1984-01-01

354

Calcioolivine, ?-Ca2SiO4, an old and New Mineral species  

NASA Astrophysics Data System (ADS)

Calcioolivine has been included into the MDI mineral database in the list of grandfathered minerals. Its history, together with related artificial compounds, is extremely complex: various minerals and compounds received this name, including natural orthorhombic Ca orthosilicate. In this paper, the crystal structure and properties of natural calcioolivine are described for the first time. The new mineral has been found at Mt. Lakargi, Upper Chegem Plateau, the northern Caucasus, Kabarda-Balkaria Republic, Russia. It has been identified in skarnified, primary carbonate xenoliths entrained by middle to late Pliocene silicic ignimbrites of the Upper Chegem caldera. These xenoliths of a few centimeters to a few meters in size are located close to the volcanic vent. Calcioolivine rims relics of larnite and occurs as relict grains among crystals of spurrite, rondorfite, wadalite or secondary hillebrandite, afwillite, thaumasite, and ettringite. Hillebrandite is the major product of alteration of calcioolivine; larnite is relatively more resistant to low-temperature alteration. Spurrite, larnite, tilleyite, kilchoanite, cuspidine, wadalite, rondorfite, reinhardbraunsite, lakargiite (CaZrO3), members of ellestadite series, afwillite, ettringite, katoite, and thaumasite are associated minerals. It is inferred that calcioolivine has been produced as a result of interaction of host carbonate rocks in xenoliths with volcanic lava and gases during eruption. The name calcioolivine was approved by the Commission on New Minerals and Mineral Names, International Mineralogical Association, September 6, 2007 (no. 07-B).

Zadov, A. E.; Gazeev, V. M.; Pertsev, N. N.; Gurbanov, A. G.; Gobechiya, E. R.; Yamnova, N. A.; Chukanov, N. V.

2009-12-01

355

Clay minerals in animal nutrition  

Microsoft Academic Search

Clay minerals are important in many facets of our society. Their properties such as structure and chemical composition, type of exchangeable ion and particle size determine their various uses. The healing powers of clay were known for centuries and are now being rediscovered. The practice of eating clay by animals in the wild for the detoxification of the body and

R. Slamova; M. Trckova; H. Vondruskova; Z. Zraly; I. Pavlik

2011-01-01

356

Improvements to Universal Ripper Miner.  

National Technical Information Service (NTIS)

A universal ripper miner used to cut, collect and transfer material from an underground mine working face includes a cutter head that is vertically movable in an arcuate cutting cycle by means of drive members, such as hydraulically actuated pistons. The ...

R. J. Morrell D. A. Larson

1989-01-01

357

Physical controls on matrix mineralization  

NASA Astrophysics Data System (ADS)

During biomineral formation, protein matrices impose order on nucleating mineral phases. While many studies have examined the structural relationships between mineral and matrix, few have explored the energetics. To address this gap we use in situ TEM and AFM to investigate calcium phosphate nucleation and growth in collagen and amelogenin matrices. In situ TEM results indicate that, in the absence of calcium, amelogenin nanospheres are loose aggregates of oligomers, while in the presence of calcium phosphate solution, can form chain-like structures and become mineralized with an amorphous phase before the appearance of crystalline phases. Results on collagen reveal the evolution of nucleation pathways from direct to indirect with increasing supersaturation and analysis of nucleation rates using classical theory demonstrates a reduction in interfacial energy due to matrix-mineral interactions. However, the calculated thermodynamic barriers are in contradiction to the observed pathways and well in excess of sensible values. We present a model based on cluster aggregation within the classical context that reconciles experiment and theory.

Tao, Jinhui; Nielsen, Mike; de Yoreo, Jim

2013-03-01

358

KNIME: The Konstanz Information Miner  

Microsoft Academic Search

The Konstanz Information Miner is a modular environment, which en- ables easy visual assembly and interactive execution of a data pipeline. It is designed as a teaching, research and collaboration platform, which enables simple integration of new algorithms and tools as well as data manipulation or visualization methods in the form of new modules or nodes. In this paper we

Michael R. Berthold; Nicolas Cebron; Fabian Dill; Thomas R. Gabriel; Tobias Kötter; Thorsten Meinl; Peter Ohl; Christoph Sieb; Kilian Thiel; Bernd Wiswedel

2007-01-01

359

Mineral Physics and Mantle Evolution  

NASA Astrophysics Data System (ADS)

Don Anderson has been a steadfast patron and constructive critic of mineral physics for more than 40 years. Although he has never actually done an experiment himself [except for perhaps some early work on ice when he was working in Greenland], he has nurtured and supported two generations of experimental mineral physicists throughout the U.S. His role and influence have been especially evident in studies of the elasticity and anelasticity of minerals and the use of such data for interpretation of seismic models of the Earth's mantle. In the 1960s, such acoustic experiments required specimens of centimeter dimensions and could achieve elevated conditions of less than 1 Gigapascal in pressure and a few hundred degrees of Celsius temperature. Today, one can perform such experiments on specimens only a fraction of a milimeter in size and reach pressures of tens of GPa and temperatures in excess of two thousand degrees C. In addition, Anderson's contributions to organized scientific endeavors have extended far beyond his founding role in IRIS to include advising on the establishment of the new Consortium for Materials Properties Research in Earth Sciences [COMPRES]. We ilustrate his remarkable contributions to mineral physics with examples of our own research, some of it done in collaboration with Anderson.

Liebermann, R. C.; Bass, J. D.; Weidner, D. J.

2003-12-01

360

Knime: The Konstanz Information Miner  

Microsoft Academic Search

The Konstanz Information Miner is a modular environ- ment which enables easy visual assembly and interactive execution of a data pipeline. It is designed as a teaching, research and collaboration platform, which enables easy integration of new algorithms, data manipulation or vi- sualization methods as new modules or nodes. In this paper we describe some of the design aspects of

Michael R. Berthold; Nicolas Cebron; Fabian Dill; Thomas R. Gabriel; Florian Georg; Thorsten Meinl; Peter Ohl; Christoph Sieb; Bernd Wiswedel

2006-01-01

361

Crystallizing Minerals from Aqueous Solutions  

NSDL National Science Digital Library

Students dissolve selected salts and other compounds in water, let the water evaporate for about three weeks, and examine the crystals that grow. Students then draw crystal shapes and discuss the experiment. Discussion can include why and how crystals grow from solutions, why some minerals dissolve well and others do not, concepts of symmetry, and crystal systems and point groups.

Perkins, Dexter

362

Radioactive Gas in Mineral Springs  

Microsoft Academic Search

IN a letter to NATURE of August 13, 1903, it was announced that experiments carried out at the Blythswood Laboratory had shown the presence of a radio-active constituent in the gases derived from the mineral waters of Bath. An account of our further investigations has been given in a paper read before the Royal Philosophical Society of Glasgow, November 18,

Blythswood; H. S. Allen

1904-01-01

363

Road map to mineral supply  

NASA Astrophysics Data System (ADS)

Access to metals and minerals is restricted mostly by geopolitical constraints, and not by a shortage of mineable deposits. In the face of rising demand, a full inventory of these commodities -- in the Earth's crust as well as in recyclable waste -- is urgently required.

Herrington, Richard

2013-11-01

364

Silicon Oxynitride: A Meteoritic Mineral.  

PubMed

Silicon oxynitride, a new mineral, has been discovered in the Jajh deh Kot Lalu enstatite chondrite. Nitrogen and oxygen have been measured quantitatively with an electron microprobe by means of prototypes of newly developed curved crystal detection systems. X-ray diffraction patterns were obtained from silicon oxynitride separated from the meteorite and from synthetic Si(2)N(2)O. PMID:17743707

Andersen, C A; Keil, K; Mason, B

1964-10-01

365

Elastic Properties of Mantle Minerals  

NASA Astrophysics Data System (ADS)

The most direct information about the interior structure of the Earth comes from seismic wave velocities. Interpretation of seismic data requires an understanding of how sound velocities and elastic properties of minerals vary with pressure, temperature, crystal structure, and composition as well as the role of anelasticity, melts, etc. More generally, elastic moduli are important for understanding many solid-state phenomena including mechanical stability, interatomic interactions, material strength, compressibility, and phase transition mechanisms. The database of mineral elasticity measurements has been growing rapidly in recent years. In this work, we report initial results of an ongoing survey of our current knowledge of mineral elasticity at both ambient conditions and high pressures and temperatures. The analysis is selective, emphasizing single crystal measurements but also incorporating polycrystalline measurements and volume compression data as appropriate. The goal is to synthesize our current understanding of mineral elasticity in terms of structure and composition, and to identify the major remaining needs for experimental and theoretical work. Clinopyroxenes (Cpx) provide an example of our approach. A wide range of clinopyroxene compositions are found geologically and Mg-, Ca-, and Na-rich clinopyroxenes are expected to be important components in the upper mantle. The single-crystal elastic properties of a number of endmember Cpx compositions have been measured and these exhibit a range of ~25% in shear velocity. Those with monovalent cations (spodumene, jadeite) in the M2 site exhibit the highest velocities while Fe-rich (hendenbergit, acmite) compositions have the lowest velocities. The effects on velocity due to a wide range of chemical substitutions can be defined, but there are important discrepancies and omissions in the database. New measurements of omphacites, intermediate diopside-hedenbergite compositions, aegerine/acmite, augite, etc. are clearly needed. We also show how the combination of single-crystal elasticity data and volume compression data for diopside can be used to constrain the pressure derivative of the bulk modulus -- an important parameter for modeling seismic velocities in mantle assemblages. More broadly, the mineral elasticity data set can provide insights into the systematic variation of elastic properties that are of great importance in mineral physics and geophysics. We will examine the role of anisotropy, Vp/Vs variations, pressure derivatives of elastic moduli, and auxetic behavior to name a few properties of interest. The pioneering work on mineral elasticity carried out by Bob Liebermann has made an immense contribution to this important database, as well as providing strong scientific motivation for this work.

Duffy, T. S.; Stan, C. V.

2012-12-01

366

Comparative study of stream sediments and heavy mineral concentrates using SEM-based Automated Mineralogy (QEMSCAN) from remote areas of Northern Pakistan  

NASA Astrophysics Data System (ADS)

This study investigates the usefulness of QEMSCAN for mineralogical analysis of stream sediments and heavy mineral concentrates. This study was an orientation study of known and lesser understood gold-rich prospect areas in northern Pakistan. Mineralogical anomalies in this area are more obvious in heavy mineral concentrates than stream sediments from both known and lesser known areas, probably as a result of dilution by glacial material. The sampling strategy involved the collection of stream sediments (<180 ?m) and panned concentrates (<180 ?m) from known Shoghor and Bagrot prospects and lesser understood areas such as Asheriat, Teru and Pakora where the sources of the anomalies were unknown. Samples from all areas were analysed by conventional ICP-MS and XRF, as well as detailed physiochemical study of gold grains observed in panned concentrates. A selected number (16) of samples from stream sediments and heavy minerals were subjected to advance mineralogical analysis using QEMSCAN. Data were output on the modal mineralogy and mineral associations for both heavy mineral concentrates and stream sediments. The mineral proportions and associations in the heavy mineral concentrates (<180 ?m) from the Shoghor and Bagrot catchments were characteristic of their known styles of mineralization, containing stibnite, galena, chalcopyrite and arsenopyrite, along with secondary minerals such as PbSbO (probably bindheimite) and SbO (possibly stibiconite). The modal abundances and associations of sulphide minerals and also secondary phases were better detected in the heavy mineral concentrates than stream sediments as concentrations of the latter were often below detection limits. The known Pb-Sb mineralization in Shoghor was well defined by modal mineralogy and mineral associations of rare minerals including stibnite, galena and also secondary phases such as SbO and PbSbO. Furthermore indication of similar types of mineralization have been found in heavy mineral concentrates from the lesser known Asheriat, Teru and Pakora areas. Results from both media indicated the mineralogy of sources and are useful to mineral exploration, either on their own or in combination with conventional geochemical methods. However the panned concentrates give more useful information than stream sediments and is recommended for detailed study of sulphide minerals, although costs are currently high (~£250 per sample). Detection limits for automated mineralogy are comparable to those of ICP-MS for transition metals.

ALI, L.; Williamson, B.; Moon, C. J.; Rollinson, G.; Shah, M. T.

2012-12-01

367

Secondary air control damper arrangement  

SciTech Connect

The outline of a tangentially-fired furnace combustion chamber is arranged to show a representative windbox in one corner of the furnace. The secondary air is disclosed as supplied through one set of vertically tiltable nozzles mounted in the windbox. The secondary air supply conduit is mounted to feed the tiltable nozzles. The secondary air supply conduit section adjacent to the nozzles has straightening vanes forming channels in which independently controlled louvers regulate the total cross-sectional area of the channels to maintain the desired velocity of the secondary air through the nozzles.

Chadshay, R.

1984-01-17

368

Assessing the addition of mineral processing waste to green waste-derived compost: an agronomic, environmental and economic appraisal.  

PubMed

The overall aim of this study was to evaluate the benefit of mixing two large volume wastes, namely mineral processing waste and source-segregated green waste compost, on the growth performance of plants targeted towards high (horticulture/agriculture) and low (amenity/restoration) value markets. The secondary aims were to evaluate the influence of mineral waste type on plant growth performance and to undertake a simple economic analysis of the use of mineral-compost mixtures in land restoration. Our results showed that in comparison to organic wastes, mineral wastes contained a low available nutrient content which reduces compost quality. This is supported by growth trials with tomato, wheat and grass which showed that, irrespective of mineral source, plants performed poorly in compost blended with mineral waste in comparison to those grown in green waste or peat-based compost alone. In terms of consumer confidence, unlike other wastes (e.g. biosolids and construction/demolition waste) the mineral quarry wastes can be expected to be free of potentially toxic elements, however, the production costs of compost-mineral waste mixtures and subsequent transport costs may limit its widespread use. In addition, handling of the material can be difficult under wet conditions and effective blending may require the purchase of specialist equipment. From our results, we conclude that mineral fines may prove useful for low quality, low value landscaping activities close to the source of production but are unsuited to high value markets. PMID:18809319

Jones, D L; Chesworth, S; Khalid, M; Iqbal, Z

2009-01-01

369

Vitamin and Mineral Supplement Fact Sheets  

MedlinePLUS

... view as pdf | share Create PDF Vitamin and Mineral Supplement Fact Sheets A - E | F - L | M - S | ... Information Botanical Dietary Supplements: Background Information Vitamin and Mineral Fact Sheets Botanical Supplement Fact Sheets Frequently Asked ...

370

A personal miner's carbon monoxide alarm  

SciTech Connect

Underground miners may be exposed to hazardous quantities of toxic gases, such as carbon monoxide (CO), generated from mine fires or explosions. Every underground miner is required to carry a filter self-rescuer (FSR), which when operated will remove CO from the miner's breathing air. In addition, every underground miner must have a self-contained self-rescuer(SCSR) near the worksite that will supply breathing oxygen. In many situations, miners do not know when to don either rescuer since they do not know if there is a fire in the mine, nor do they carry instrumentation necessary for the detection of the toxic, colorless, and odorless fire product CO. If each miner carried a personal CO alarm, which would respond to high concentrations of CO, the miner would then be alerted when to don either the FSR or SCSR and exit the mine. The authors report on the development of a prototype personal miner's CO alarm called PEMCOAL.

Chilton, J.E.; Carpenter, C.R.

1989-01-01

371

Reaction of Sodium Hydroxide with Silicate Minerals.  

National Technical Information Service (NTIS)

The reactions of individual silicate minerals with caustic solution were measured over a 1-week period. These silicate minerals included: two feldspars (microcline and albite), two micas (biotite and muscovite), and three clays (chlorite, Kaolinite and mo...

S. D. Thornton

1986-01-01

372

World Mineral Production, 2004-08.  

National Technical Information Service (NTIS)

World Mineral Production covers the majority of economically important mineral commodities. For each commodity constant efforts are made to ensure that as many producing countries as possible are reported. For some commodities, where statistics on product...

L. E. Hetherington N. E. Idoine S. D. Hannis T. Bide T. J. Brown

2010-01-01

373

Mine and mineral occurrences of Afghanistan  

USGS Publications Warehouse

This inventory of more than 1000 mines and mineral occurrences in Afghanistan was compiled from published literature and the files of project members of the National Industrial Minerals project of the U.S. Geological Survey. The compiled data have been edited for consistency and most duplicates have been deleted. The data cover metals, industrial minerals, coal, and peat. Listings in the table represent several levels of information, including mines, mineral showings, deposits, and pegmatite fields.

Orris, G. J.; Bliss, J. D.

2002-01-01

374

[Incidence of chronic bronchitis in coal miners].  

PubMed

An epidemiological survey of 2000 Donbass coal miners revealed data on the initial dust bronchitis prevalence and its progress. It was established that the coal miners who work in mines with steep coal strata exhibit higher bronchitis morbidity in comparison with the miners engaged in sloping strata mines. A correlation was established between dust bronchitis prevalence and length of professional service and coal miners' labour specificity. Tobacco smokers displayed a markedly higher percentage of chronic dust bronchitis cases. PMID:2379850

Valutsina, V M; Kiva, A I

1990-01-01

375

Two-Stage Mineralization of Phenanthrene by Estuarine Enrichment Cultures  

PubMed Central

The polycyclic aromatic hydrocarbon phenanthrene was mineralized in two stages by soil, estuarine water, and sediment microbial populations. At high concentrations, phenanthrene was degraded, with the concomitant production of biomass and accumulation of Folin-Ciocalteau-reactive aromatic intermediates. Subsequent consumption of these intermediates resulted in a secondary increase in biomass. Analysis of intermediates by high-performance liquid chromatography, thin-layer chromatography, and UV absorption spectrometry showed 1-hydroxy-2-naphthoic acid (1H2NA) to be the predominant product. A less pronounced two-stage mineralization pattern was also observed by monitoring 14CO2 production from low concentrations (0.5 mg liter?1) of radiolabeled phenanthrene. Here, mineralization of 14C-labeled 1H2NA could explain the incremental 14CO2 produced during the later part of the incubations. Accumulation of 1H2NA by isolates obtained from enrichments was dependent on the initial phenanthrene concentration. The production of metabolites during polycyclic aromatic hydrocarbon biodegradation is discussed with regard to its possible adaptive significance and its methodological implications.

Guerin, William F.; Jones, Galen E.

1988-01-01

376

Different forms of DMP1 play distinct roles in mineralization.  

PubMed

Dentin matrix protein-1 (DMP1) is a major synthetic product of hypertrophic chondrocytes and osteocytes. Previous in vitro studies showed full-length DMP1 inhibits hydroxyapatite (HA) formation and growth, while its N-terminal fragment (37K) promotes HA formation. Since there are 3 fragments within the mineralized tissues [N-terminal, C-terminal (57K), and a chondroitin-sulfate-linked N-terminal fragment (DMP1-PG)], we predicted that each would have a distinct effect on mineralization related to its interaction with HA. In a gelatin-gel system, 37K and 57K fragments were both promoters of HA formation and growth; DMP1-PG was an inhibitor. The secondary structures of the 3 fragments and the full-length protein in the presence and absence of Ca2+ and HA determined by FTIR showed that the full-length protein undergoes slight conformational changes on binding to HA, while 37K, 57K, and DMP1-PG do not change conformation. These findings indicate that distinct forms of DMP1 may work collectively in controlling the mineralization process. PMID:20200415

Gericke, A; Qin, C; Sun, Y; Redfern, R; Redfern, D; Fujimoto, Y; Taleb, H; Butler, W T; Boskey, A L

2010-04-01

377

Mineral transformations associated with goethite reduction by Methanosarcina barkeri  

USGS Publications Warehouse

To investigate the interaction between methanogens and iron-containing minerals in anoxic environments, we conducted batch culture experiments with Methanosarcina barkeri in a phosphate-buffered basal medium (PBBM) to bioreduce structural Fe(III) in goethite with hydrogen as the sole substrate. Fe(II) and methane concentrations were monitored over the course of the bioreduction experiments with wet chemistry and gas chromatography, respectively. Subsequent mineralogical changes were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM). In the presence of an electron shuttle anthraquinone-2,6-disulfonate (AQDS), 30% Fe(III) in goethite (weight basis) was reduced to Fe(II). In contrast, only 2% Fe(III) (weight basis) was bioreduced in the absence of AQDS. Most of the bioproduced Fe(II) was incorporated into secondary minerals including dufr??nite and vivianite. Our data implied a dufr??nite-vivianite transformation mechanism where a metastable dufr??nite transformed to a more stable vivianite over extended time in anaerobic conditions. Methanogenesis was greatly inhibited by bioreduction of goethite Fe(III). These results have important implications for the methane flux associated with Fe(III) bioreduction and ferrous iron mineral precipitation in anaerobic soils and sediments. ?? 2011 Elsevier B.V.

Liu, D.; Wang, H.; Dong, H.; Qiu, X.; Dong, X.; Cravotta, C. A.

2011-01-01

378

Secondary paroxysmal dyskinesias.  

PubMed

Paroxysmal dyskinesias (PxDs) are involuntary, episodic movements that include paroxysmal kinesigenic (PKD), paroxysmal nonkinesigenic (PNKD), and paroxysmal hypnogenic (PHD) varieties. Although most PxDs are primary (idiopathic or genetic), we found 17 of our 76 patients with PxD (22%) to have an identifiable cause for their PxD (10 men; mean age, 41.4 years). Causes included peripheral trauma (in three patients), vascular lesions (in four), central trauma (in four), kernicterus (in two), multiple sclerosis (in one), cytomegalovirus encephalitis (in one), meningovascular syphilis (in one), and migraine (in one). The latency from insult to symptom onset ranged from days (trauma) to 18 years (kernicterus), with a mean of 3 years. Nine patients had PNKD, two had PKD, five had mixed PKD/PNKD, and one had PHD. Hemidystonia was the most common expression of the paroxysmal movement disorder, present in 11 patients. Both of the patients with PKD had symptom durations of <5 minutes. Symptom duration ranged from 10 seconds to 15 days for PNKD and from 5 minutes to 45 minutes for mixed PKD/PNKD. There were no uniformly effective therapies, but anticonvulsant drugs, clonazepam, and botulinum toxin injections were the most beneficial. Awareness of the variable phenomenology and the spectrum of causes associated with secondary PxD will allow for more timely diagnosis and early intervention. PMID:12210862

Blakeley, Jaishri; Jankovic, Joseph

2002-07-01

379

Competing Fe (II)-induced mineralization pathways of ferrihydrite.  

PubMed

Owing to its high surface area and intrinsic reactivity, ferrihydrite serves as a dominant sink for numerous metals and nutrients in surface environments and is a potentially important terminal electron acceptor for microbial respiration. Introduction of Fe (II), by reductive dissolution of Fe(III) minerals, for example, converts ferrihydrite to Fe phases varying in their retention and reducing capacity. While Fe(II) concentration is the master variable dictating secondary mineralization pathways of ferrihydrite, here we reveal thatthe kinetics of conversion and ultimate mineral assemblage are a function of competing mineralization pathways influenced by pH and stabilizing ligands. Reaction of Fe(II) with ferrihydrite results in the precipitation of goethite, lepidocrocite, and magnetite. The three phases vary in their precipitation extent, rate, and residence time, all of which are primarily a function of Fe(II) concentration and ligand type (Cl, SO4, CO3). While lepidocrocite and goethite precipitate over a large Fe(II) concentration range, magnetite accumulation is only observed at surface loadings greater than 1.0 mmol Fe(II)/g ferrihydrite (in the absence of bicarbonate). Precipitation of magnetite induces the dissolution of lepidocrocite (presence of Cl) or goethite (presence of SO4), allowing for Fe(III)-dependent crystal growth. The rate of magnetite precipitation is a function of the relative proportions of goethite to lepidocrocite; the lower solubility of the former Fe (hydr)oxide slows magnetite precipitation. A one unit pH deviation from 7, however, either impedes (pH 6) or enhances (pH 8) magnetite precipitation. In the absence of magnetite nucleation, lepidocrocite and goethite continue to precipitate at the expense of ferrihydrite with near complete conversion within hours, the relative proportions of the two hydroxides dependent upon the ligand present. Goethite also continues to precipitate at the expense of lepidocrocite in the absence of chloride. In fact, the rate and extent of both goethite and magnetite precipitation are influenced by conditions conducive to the production and stability of lepidocrocite. Thus, predicting the secondary mineralization of ferrihydrite, a process having sweeping influences on contaminant/nutrient dynamics, will need to take into consideration kinetic restraints and transient precursor phases (e.g., lepidocrocite) that influence ensuing reaction pathways. PMID:16201641

Hansel, Colleen M; Benner, Shawn G; Fendorf, Scott

2005-09-15

380

Image Archive: The Physical Properties of Minerals  

NSDL National Science Digital Library

This presentation provides a detailed explanation of the physical properties of minerals. It covers the classic four-part definition of "mineral" and provides an overview of the physical properties by which minerals are identified. Each property is illustrated with one or more photographs.

Celestian, Susan

381

Minerals, national security, and foreign policy  

Microsoft Academic Search

As the world's principal minerals-consuming nation, the United States has a long history of concern about access to the minerals necessary to the functioning of its economy and maintaining a strong national defense (Eckes, 1979). These concerns first arose after World War I when the nation recognized that it was not self-sufficient in all of the minerals it needed. Although

W. David Menzie

1997-01-01

382

Observe common objects made of minerals  

NSDL National Science Digital Library

This interactive Earth science resource lets students first see six images of minerals and then, by placing their cursor over each image, an image of an everyday object made from that mineral. Quartz, gypsum, and fluorite are among the minerals shown, with the corresponding familiar objects being glass, drywall (Sheetrock), and toothpaste. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

383

Rock-Forming Minerals in Thin Section  

NSDL National Science Digital Library

This page is designed to display some of the most significant features of minerals viewed in thin section, and to show the most conspicuous features of major rock-forming minerals. A description of optical properties, specific mineral images, and discrimination tables are provided.

Dutch, Steven

384

Mineral matter identification of some Turkish lignites  

SciTech Connect

Samples of 15 Turkish lignites were oxidized by performic acid. Their mineral matter was isolated without any important chemical decomposition. The X-ray diffraction method was employed to determine the mineral species in the isolated mineral matter and in the ashes of the lignite samples. The results were compared and discussed.

Yaman, S.; Taptik, Y.; Kuecuekbayrak, S.; Kadioglu, E. [Istanbul Technical Univ. (Turkey). Chemical and Metallurgical Engineering Faculty

1995-01-01

385

Carbon dioxide sequestration by mineral carbonation  

Microsoft Academic Search

The increasing atmospheric carbon dioxide (CO2) concentration, mainly caused by fossil fuel combustion, has lead to concerns about global warming. A possible technology that can contribute to the reduction of carbon dioxide emissions is CO2 sequestration by mineral carbonation. The basic concept behind mineral CO2 sequestration is the mimicking of natural weathering processes in which calcium or magnesium containing minerals

W. J. J. Huijgen; R. N. J. Comans

2007-01-01

386

Introduction to Crystallography and Mineral Crystal Systems  

NSDL National Science Digital Library

This illustrated, nine-part primer on crystallography and mineral crystal systems was developed by a professional geologist and long-time mineral collector. His objective is to bring a greater appreciation of natural mineral crystals and their forms by providing some background and understanding of the world of crystallography.

Keller, Bob

387

BONE MINERAL DENSITY OF BANGLADESHI PEOPLE  

Microsoft Academic Search

This work is aimed to know about bone mineral density and its influence on bone health. For a preliminary study 30 patients of Nuclear Medicine Centre at Comilla, Bangladesh were chosen. After thorough physical observation and medical examination, their bone mineral density (BMD) and bone mineral content (BMC) at different sites were measured using Dual Energy X-ray Absorptiometer (DEXA). Correlations

Dilruba Akhter Banu

2009-01-01

388

Exploration for uranium deposits, Grants mineral belt  

Microsoft Academic Search

Uranium ore deposits in the Grants mineral belt, New Mexico, occur in fluvial sandstones in the Morrison Formation (Jurassic). Uranium mineralization is concentrated by a dark-gray to black substance that has been identified as humate, which is derived from decaying vegetation. Black ore is truncated by overlying sandstone in at least three ore deposits, documenting an early age for mineralization.

Fitch

1980-01-01

389

Uranium Miner Lung Cancer Study. Final Report.  

National Technical Information Service (NTIS)

This study on uranium miners was started in 1957 and extended through June 30, 1986. It consisted of the routine screening of sputum from uranium miners of the Colorado Plateau, and collection of surgical and autopsy material from uranium miners who devel...

G. Saccomanno

1986-01-01

390

A nitrogen mineralization model based on relationships for gross mineralization and immobilization  

Microsoft Academic Search

Net N mineralization from plant materials represents the difference between the two opposing processes of gross N mineralization and immobilization. This complicates the derivation of useful relationships between rates of net mineralization and litter quality indices. The purpose of the current paper is to present a model for net N mineralization from plant material that is based on relationships between

Sander Bruun; Jesper Luxhøi; Jakob Magid; Andreas de Neergaard; Lars S. Jensen

2006-01-01

391

25 CFR 215.25 - Other minerals and deep-lying lead and zinc minerals.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Other minerals and deep-lying lead and zinc minerals. 215.25 Section 215.25 Indians...LEASES, QUAPAW AGENCY § 215.25 Other minerals and deep-lying lead and zinc minerals. Except as provided in §...

2010-04-01

392

25 CFR 215.25 - Other minerals and deep-lying lead and zinc minerals.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Other minerals and deep-lying lead and zinc minerals. 215.25 Section 215.25 Indians...LEASES, QUAPAW AGENCY § 215.25 Other minerals and deep-lying lead and zinc minerals. Except as provided in §...

2009-04-01

393

Ambient temperature secondary Li/FeS2 cells  

NASA Astrophysics Data System (ADS)

The natural pyrite mineral FeS2 is found to be at least a partially rechargeable cathode material. The study demonstrates 22 deep cycles in cells with 'practical' cathode capacity densities. The long-term rechargeability shown in high-temperature cells is considered to suggest the high cycle life and secondary properties of FeS2. The results establish the technical possibility of applying FeS2 as a high rate cathode material in primary lithium cells which contain lithium organoborate electrolytes.

Newman, G. H.; Klemann, L. P.

394

Metabolomics for Secondary Metabolite Research  

PubMed Central

Metabolomics, the global characterization of metabolite profiles, is becoming an increasingly powerful tool for research on secondary metabolite discovery and production. In this review we discuss examples of recent technological advances and biological applications of metabolomics in the search for chemical novelty and the engineered production of bioactive secondary metabolites.

Breitling, Rainer; Ceniceros, Ana; Jankevics, Andris; Takano, Eriko

2013-01-01

395

Combinatorics of RNA Secondary Structures  

Microsoft Academic Search

Secondary structures of polynucleotides can be viewed as a class of planar vertex-labeled graphs. We compute recursion formulae for enumerating a variety sub-classes of and classes of sub-graphs (structural elements) of secondary structure graphs. First order asymptotics are derived and their dependence on the composition of the underlying nucleic acid sequences is discussed.

Ivo L. Hofacker; Peter Schuster; Peter F. Stadler

1998-01-01

396

Computers in Swiss Secondary Education.  

ERIC Educational Resources Information Center

This paper describes the current state of secondary school computer literacy instruction in the Swiss canton of Vaud and the activities of a nationwide coordinating group concerned with the use of computers in Swiss secondary education. Information is presented on the requirements for instituting computer literacy instruction in Vaud, the types of…

Bron, Alain

397

Metabolomics for secondary metabolite research.  

PubMed

Metabolomics, the global characterization of metabolite profiles, is becoming an increasingly powerful tool for research on secondary metabolite discovery and production. In this review we discuss examples of recent technological advances and biological applications of metabolomics in the search for chemical novelty and the engineered production of bioactive secondary metabolites. PMID:24958266

Breitling, Rainer; Ceniceros, Ana; Jankevics, Andris; Takano, Eriko

2013-01-01

398

INDUCED SECONDARY COMBUSTION IN WOODSTOVES  

EPA Science Inventory

The paper provides information useful for woodstove designers concerned with reducing emissions. A dual-chamber woodstove was modified to induce secondary combustion by utilizing an ignition source and forced flow of secondary air. The ignition source was an electric glow plug in...

399

N Reactor secondary loop contamination  

Microsoft Academic Search

N Reactor primary loop water circulates entirely within Zone 1 and the piping is, therefore, heavily shielded. Secondary loop piping crosses the Zone 1 boundaries into areas which may be unshielded and accessible during reactor operation. The leakage of primary loop water to the secondary side of the cooling loop permits contaminated fluid to leave the shielded area. It becomes

Stepnewski

1963-01-01

400

Status Update for the MINER$\  

SciTech Connect

MINER{nu}A (Main INjEctoR {nu}-A) is a few-GeV neutrino cross section experiment that began taking data in the FNAL NuMI beam-line in the fall of 2009. MINER{nu}A employs a fine-grained detector capable of complete kinematic characterization of neutrino interactions. The detector consists of an approximately 6.5 ton active target region composed of plastic scintillator with additional carbon, iron, and lead targets upstream of the active region. The experiment will provide important inputs for neutrino oscillation searches and a pure weak probe of nuclear structure. Here we offer a set of initial kinematic distributions of interest and provide a general status update.

Perdue, Gabriel

2011-05-01

401

The Lifecycle of a Mineral Deposit: A Teache's Guide for Hands-On Mineral Education Activities  

NSDL National Science Digital Library

This teacher's guide provides an introduction to the process of finding or exploring for a mineral deposit, extracting or mining the resource, recovering it, and reclaiming the mined area (sometimes called 'beneficiation' or 'life cycle'). Topics include what a mineral deposit is; how they are identified and measured, how the minerals are extracted; and how the mining site is reclaimed. There is also discussion of how minerals and mineral resources are processed and how they are used in everyday life. The guide includes ten activities that educate students on basic geologic concepts; the processes of finding, identifying, and extracting the resources from a mineral deposit; and the uses of minerals.

402

Energy, minerals and western security  

SciTech Connect

How secure are the mineral supplies of the industrial world. The alarm or quiet assurance which alternate in the answers periodically given to this question often lack an adequate basis. This book provides a systematic analysis of threats and possible responses. The author, a German political scientist, believes that the industrial nations can cope with some pretty hard knocks, but makes judicious suggestions for a number of policies that would reduce the danger and improve the responses.

Maull, H.W.

1985-01-01

403

Evaporites, petroleum and mineral resources  

SciTech Connect

This book illustrates the expanding knowledge of evaporites as important reservoir seals, fluid aquitards, ore-hosting sediments, and economically viable sediments in their own right. Researchers, oil and gas professionals, minerals resource professionals, environmental specialists and others within geology and the other earth sciences shall utilize the information within this book in their understanding of the many recent discoveries and concepts involved in the field of evaporite sedimentology.

Melvin, J.L.

1991-01-01

404

Simulating the Changes of Minerals and Elements under Chemical Weathering by Acid Hydrothermal Experiments  

NASA Astrophysics Data System (ADS)

In paleoenvironmental research, previous investigations reveal that the intensity of chemical weathering can be inferred from the elemental variations of marine or lacustrine sediments. Different kinds of rocks from Taiwan were applied in hydrothermal experiments to simulate element proportions and leaching sequence under chemical weathering. In our experiments, powder samples (2g) are treated in sulfuric acid solutions (20 ml) of 0.05M and 0.5M at 150°C for 1, 4, 7, 14, 30 and 60 days, respectively. We can further discuss mineral alteration and relative elemental migration according to the experimental results. There is no obvious variation in mineral phase and element at 0.05M, but the results of 0.5M have significant variations. The elemental contents are affected by the mineral leaching and secondary mineral deposited, so we use XRD and SEM to identify the existence of secondary minerals and their compositions. Our research exhibits that K/Rb, Ti/Al and Rb/Sr ratios show similar trend in most parent rocks (i.e. granite, andesite, quartz sandstone, calcite sandstone and mudstone) at 0.5M long-term experiments; however, the CIA value, was generally used as the proxy of chemical weathering, keep in a stable condition. The K/Rb and Ti/Al ratio increase, but Rb/Sr ratio decreases. In contrast, the actinolite schist and serpentinite show the different result. It is probably caused by the major mineral, chlorite and serpentinite in the rocks. We conclude that the major element Ti is relatively stable. Therefore, we use each element divided by Ti for judging relatively enriched or depleted under chemical weathering processes. Finally, we find that K/Rb ratio, which has obvious variations, is seldom influenced by mineral assemblage, so it can be regarded as a suitable weathering proxy.

Lo, F.; Chen, H.

2013-12-01

405

Control Dewar Secondary Vacuum Container  

SciTech Connect

This engineering note provides background information regarding the control dewar secondary vacuum container. The secondary vacuum container has it's origin with the CDP control dewar design. The name secondary vacuum container replaced the CDP term 'Watt can' which was named after Bob Watt (SLAC), a PAC/DOE review committee member who participated in a review of CDP and recommended a secondary vacuum enclosure. One of the most fragile parts of the control dewar design is the ceramic electrical feed throughs located in the secondary vacuum container. The secondary vacuum container is provided to guard against potential leaks in these ceramic insulating feed throughs. The secondary vacuum container has a pumping line separate from the main solenoid/control dewar insulating vacuum. This pumping line is connected to the inlet of the turbo pump for initial pumpdown. Under normal operation the container is isolated. Should a feedthrough develop a small leak, alternate pumping arrangements for the secondary vacuum container could be arranged. The pressure in the secondary vacuum container should be kept in a range that the breakdown voltage is kept at a maximum. The breakdown voltage is known to be a function of pressure and is described by a Paschen curve. I cannot find a copy of the curve at this time, but from what I remember, the breakdown voltage is a minimum somewhere around 10-3 torr. Ideally the pressure in the secondary vacuum can should be kept very low, around 10 E-6 or 10 E-7 torr for maximum breakdown voltage. If however a leak developed and this was not possible, then one could operate at a pressure higher than the minima point.

Rucinski, R.; /Fermilab

1993-10-04

406

Mines and Mineral Occurrences of Afghanistan  

NSDL National Science Digital Library

The USGS has recently released the report Mines and Mineral Occurrences of Afghanistan in Adobe Acrobat (.pdf) format. The 95-page open file report is an inventory of more than 1000 mines and mineral occurrences in the country that resources that include metals, industrial minerals, coal, and peat. The data was compiled from published literature and digital files of the members of the National Industrial Minerals project, and are presented in tables that list mineral showings, deposits, and pegmatite fields. This site is also reviewed in the May 3, 2002 Scout Report.

2002-01-01

407

30 CFR 581.8 - Rights to minerals.  

Code of Federal Regulations, 2010 CFR

30 Mineral Resources 2 2012-07-01 2012-07-01 false Rights to minerals. 581.8 Section 581.8 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE LEASING OF MINERALS...

2012-07-01

408

25 CFR 225.22 - Approval of minerals agreements.  

Code of Federal Regulations, 2010 CFR

...2012-04-01 2011-04-01 true Approval of minerals agreements. 225.22 Section 225.22...DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS OIL AND GAS, GEOTHERMAL, AND SOLID MINERALS AGREEMENTS Minerals Agreements §...

2012-04-01

409

Geochemistry of clay minerals for uranium exploration in the Grants mineral belt, New Mexico  

Microsoft Academic Search

Clay mineralogy studies of ore rocks versus barren rocks in the Grants mineral belt, New Mexico, show that some combination of chlorite (rosette form), illite, mixed-layer illite-montmorillonite, (±Mg-montmorillonite) are penecontemporaneous with uranium minerals in trend ore; these same clay minerals plus kaolinite are related to the roll-type ore near the main redox front of the Grants mineral belt. Clay minerals

D. G. Brookins

1982-01-01

410

Mineral Physics and US Array  

NASA Astrophysics Data System (ADS)

The US Array seismological observatory of Earthscope will produce high-resolution images of the seismic velocity structure of the mantle, ranging from the shallow lithospheric mantle under North America, to detailed images of the core-mantle boundary. Basic properties such as seismic velocities, anisotropy, heterogeneity, and attenuation should be constrained with unprecedented precision, and will be critical for accurately constraining the present composition, temperature, and flow patterns throughout the mantle. In order to convert the seismic information into quantities of interest, such as composition, temperature, preferred orientation (texture), and state (e.g., solid versus liquid), it is essential to have knowledge of the sound velocities and densities of a broad suite of candidate mantle phases under pressure-temperature conditions that closely mimic those in the mantle. Moreover, accurate velocity-density relationships are critical for identifying the buoyancy that drive flow. In this talk we review some of the more recent advances in determining the sound velocities of minerals, and some of the recent results. Interdisciplinary efforts to integrate new seismological and mineral physics results are likely to greatly further our understanding of Earth's deep interior. An excellent example is the discovery of a post-perovskite phase which can appears to explain many of the unusual seismic features of the D" region about the core-mantle boundary, and which may serve as a thermometer for the lowermost part of the mantle. Many unresolved fundamental questions remain to be explored, and these pose challenges to both the mineral physics and seismological communities. The distribution of water and other volatile components in the upper mantle is highly uncertain, yet it will likely to have a major effect on velocity structure and rheology. Recent high-pressure and high P-T mineral physics results tend to indicate that simple compositional models of the transition zone cannot be reconciled with existing 1-D models of this region, which may be a repository for cold subducted slabs and/or detached lithospheric blobs. Intermittent seismic reflectors in the upper and lower mantle still require explanations; those in the upper part of the lower mantle are possibly explained by silica-rich subducted basalt, calling into question the concept of subducted material at the core-mantle boundary. Simple assumptions about velocity heterogeneity being purely thermal in nature are likely invalid, and in many instances probably are reflect changes in composition as well. Some of the major challenges for future mineral physics research, and opportunities that may be exploited using US Array data and coordinated efforts with seismologists will be discussed.

Bass, J. D.

2008-12-01

411

Mortality among sulfide ore miners  

SciTech Connect

Lung cancer mortality was studied during 1965-1985 in Outokumpu township in North Karelia, where an old copper mine was located. Age-specific lung cancer death rates (1968-1985) were higher among the male population of Outokumpu than among the North Karelian male population of the same age excluding the Outokumpu district (p less than .01). Of all 106 persons who died from lung cancer during 1965-1985 in Outokumpu township, 47 were miners of the old mine, 39 of whom had worked there for at least three years and been heavily exposed to radon daughters and silica dust. The study cohort consisted of 597 miners first employed between 1954 and 1973 by a new copper mine and a zinc mine, and employed there for at least 3 years. The period of follow-up was 1954-1986. The number of person-years was 14,782. The total number of deaths was 102; the expected number was 72.8 based on the general male population and 97.8 based on the mortality of the male population of North Karelia. The excess mortality among miners was due mainly to ischemic heart disease (IHD); 44 were observed, the expected number was 22.1, based on the general male population, and the North Karelian expected number was 31.2 (p less than .05). Of the 44 miners who died from IHD, 20 were drillers or chargers exposed to nitroglycerin in dynamite charges, but also to several simultaneous stress factors including PAHs, noise, vibration, heavy work, accident risk, and working alone. Altogether 16 tumors were observed in the cohort. Ten of these were lung cancers, the expected number being 4.3. Miners who had died from lung cancer were 35-64 years old, and had entered mining work between 1954 and 1960. Five of the ten lung cancer cases came from the zinc mine (1.7 expected). Three of them were conductors of diesel-powered ore trains.

Ahlman, K.; Koskela, R.S.; Kuikka, P.; Koponen, M.; Annanmaeki, M. (Department of Epidemiology and Biometry, Institute of Occupational Health, Helsinki (Finland))

1991-01-01

412

Brazil: Secondary Education Profile. A Summary of "Secondary Education: Time to Move Forward." Secondary Education Series.  

ERIC Educational Resources Information Center

This paper provides a brief profile of the state of secondary education in Brazil. An overview of the organizational structure, objectives, curricular offerings, system size, and governance structure of secondary education is provided. Issues relating to the quality, equity, management, and financing of the system are discussed, and promising…

Larach, Linda

413

Minerals yearbook, 1992: Arkansas. Annual report  

SciTech Connect

Arkansas 1992 nonfuel mineral value reported by the State's mineral producers totaled $403.8 million, an increase of $43 million. Excluding clay and lime, value increased for all major mineral commodities mined in the State. Arkansas ranked 26th nationally in mineral value and led the Nation in the production of bromine and natural abrasives. Over the past decade (1983-92), Arkansas nonfuel mineral sales increased from $246.4 million to $403.8 million. Beginning in 1983, mineral sales increased each year excluding 1985 (-$2.6 million), 1986 (-$7 million), 1990 (-$1 million), and 1991 (almost -$20 million). Despite the sporadic downturn in sales, mineral value increased almost 64% over the 10-year period.

White, D.H.; Bush, W.V.

1994-03-01

414

Corneal Mineralization in Wistar Hannover Rats  

PubMed Central

We have recently started using Wistar Hannover rats in Japan and are now collecting background data. We have been frequently observing corneal mineralization in Wistar Hannover rats of both the RccHanTM:WIST and Crl:WI (Han) strains. In this study, details of corneal mineralization in Wistar Hannover rats were histopathologically and ultrastructurally investigated. According to the results, Wistar Hannover rats had a much higher incidence of corneal mineralization compared with Sprague-Dawley rats. The incidence of corneal mineralization was higher in males than females. According to the histological examination, mineral deposits were positive for calcium by von Kossa’s method. Furthermore, in response to mineralization, keratocytes probably become active to play an important role against the mineralized substance.

Hashimoto, Satomi; Doi, Takuya; Wako, Yumi; Sato, Junko; Wada, Sou; Tsuchitani, Minoru

2013-01-01

415

Corneal mineralization in wistar hannover rats.  

PubMed

We have recently started using Wistar Hannover rats in Japan and are now collecting background data. We have been frequently observing corneal mineralization in Wistar Hannover rats of both the RccHan(TM):WIST and Crl:WI (Han) strains. In this study, details of corneal mineralization in Wistar Hannover rats were histopathologically and ultrastructurally investigated. According to the results, Wistar Hannover rats had a much higher incidence of corneal mineralization compared with Sprague-Dawley rats. The incidence of corneal mineralization was higher in males than females. According to the histological examination, mineral deposits were positive for calcium by von Kossa's method. Furthermore, in response to mineralization, keratocytes probably become active to play an important role against the mineralized substance. PMID:24155560

Hashimoto, Satomi; Doi, Takuya; Wako, Yumi; Sato, Junko; Wada, Sou; Tsuchitani, Minoru

2013-09-01

416

Water in Nominally Anhydrous Minerals from Nakhlites and Shergottites  

NASA Technical Reports Server (NTRS)

Estimating the amount of water in the interior of terrestrial planets has tremendous implications on our understanding of solar nebula evolution, planet formation and geological history, and extraterrestrial volcanism. Mars has been a recent focus of such enquiry with complementary datasets from spacecrafts, rovers and martian meteorite studies. In planetary interiors, water can be dissolved in fluids or melts and hydrous phases, but can also be locked as protons attached to structural oxygen in lattice defects in nominally anhydrous minerals (NAM) such as olivine, pyroxene, or feldspar [1-3]. Measuring water in Martian meteorite NAM is challenging because the minerals are fragile and riddled with fractures from impact processes that makes them break apart during sample processing. Moreover, curing the sample in epoxy causes problems for the two main water analysis techniques, Fourier transform infrared spectrometry (FTIR) and secondary ionization mass spectrometry (SIMS). Measurements to date have resulted in a heated debate on how much water the mantle of Mars contains. SIMS studies of NAM [4], amphiboles [5], and apatites [6-8] from Martian meteorites report finding enough water in these phases to infer that the martian mantle is as hydrous as that of the Earth. On the other hand, a SIMS study of glass in olivine melt inclusions from shergottites concludes that the Martian mantle is much drier [9]. The latter interpretation is also supported by the fact that most martian hydrous minerals generally have the relevant sites filled with Cl and F instead of H [10,11]. As for experimental results, martian basalt compositions can be reproduced using water as well as Cl in the parent melts [12,13]. Here FTIR is used to measure water in martian meteorite minerals in order to constrain the origin of the distribution of water in martian meteorite phases.

Peslier, Anne H.

2013-01-01

417

Electrical conductivity of mantle minerals  

NASA Astrophysics Data System (ADS)

Electrical conductivity of mantle minerals Deep electrical conductivity profiles can provide constraints on the thermal and chemical state of the mantle. Especially, electrical conductivity is very sensitive to small amount of hydrogen and iron contents in minerals. Accurate knowledge of electrical conductivity of mantle minerals is needed to constrain water and/or iron contents in the mantle as a function of depth. We have investigated the electrical properties of olivine, wadsleyite, ringwoodite and majorite, which are main constituent minerals of the upper mantle by in situ electrical conductivity measurement using multianvil apparatus. The starting materials were olivine (Fo91) for olivine, wadsleyite and ringwoodite, and glass powder with composition of pyrolite minus olivine for majorite, respectively. In most cases, molybdenum disk electrode connecting to the sample was used as an oxygen buffer media, whose oxygen fugacity is close to Fe-FeO buffer. The electrical conductivities of the samples were measured at various pressures from 3 and 20 GPa and temperatures up to 2000K at low frequencies ranging from 0.01 to 0.1 Hz. For all the dry samples, electrical conductivity displays Arrhenian behavior over the entire investigated temperature range. In the high temperature range above 1700K, activation energies (more than 1.5 eV) tend to be higher than those in the lower temperature range (less than 1.5 eV). The absolute values of electrical conductivity (S/m) for each mineral are very similar to each other. From these measurements we noted that the electrical conductivities of dry olivine, wadsleyite and ringwoodite (less than 100 wt. ppm of water) are much lower than those previously reported (e.g., Xu et al., 1998). While conductivities of samples with certain amounts of hydrogen are comparable to that of the dry one, conductivity increases with increasing hydrogen concentrations. Activation energies of hydrogen-bearing nominally anhydrous minerals we measured decreases with increasing hydrogen concentration from nearly 1 to 0.5 eV. Using our results, we can estimate the electrical conductivity profile of the upper mantle. Comparing the reference model of Utada et al. (2003), our modeling demonstrates that the electrical conductivity of the upper mantle up to 410km discontinuity (i.e. olivine stability field) is close to that of dry olivine, whereas the electrical conductivities of dry wadsleyite, ringwoodite and majorite are much lower than the reference model. Therefore, a presence of hydrogen in their minerals or the other conductors is required to explain the high conductivity in the transition zone. References Xu, Y., Poe, B. T., Shankland, T. J. & Rubie, D. C., Electrical conductivity of olivine, wadsleyite and ringwoodite under upper-mantle conditions. Science 280, 1415-1418 (1998). Utada, H., Koyama, T., Shimizu, H. & Chave, A. D., A semi-global reference model for electrical conductivity in the mid-mantle beneath the north Pacific region. Geophys. Res. Lett. 30, 1194, doi:10.1029/2002GL016902 (2003).

Yoshino, T.; Manthilake, G.; Nishi, M.; Katsura, T.

2006-12-01

418

Mineral trioxide aggregate but not light-cure mineral trioxide aggregate stimulated mineralization.  

PubMed

The purpose of this study was to evaluate the subcutaneous response of rat connective tissue to light-cure MTA and Angelus MTA. These materials were placed in polyethylene and dentin tubes and implanted into dorsal connective tissue of Wistar rats for 30 and 60 days. The specimens were prepared to be stained with hematoxylin-eosin, Von Kossa, and without stain for polarized light and evaluated in an optic microscope. The Angelus MTA showed a mild inflammatory response at 30 days and none at 60 days, characterized by organized connective tissue, presence of some chronic inflammatory cells, and induction of mineralized tissue formation. Light-cure MTA presented a moderate chronic inflammatory response at 30 days that decreased at 60 days but was more intense than with Angelus MTA and without dystrophic calcifications. It was possible to conclude that light-cure MTA was similar to MTA at 60 days, but it did not stimulate mineralization. PMID:18155495

Gomes-Filho, João Eduardo; de Faria, Max Dougals; Bernabé, Pedro Felício Estrada; Nery, Mauro Juvenal; Otoboni-Filho, José Arlindo; Dezan-Júnior, Eloi; de Moraes Costa, Mariana Machado Teixeira; Cannon, Mark

2008-01-01

419

Extended secondary structures in proteins.  

PubMed

Super secondary structures of proteins have been systematically searched and classified, but not enough attention has been devoted to such large edifices beyond the basic identification of secondary structures. The objective of the present study is to show that the association of secondary structures that share some of their backbone residues is a commonplace in globular proteins, and that such deeper fusion of secondary structures, namely extended secondary structures (ESSs), helps stabilize the original secondary structures and the resulting tertiary structures. For statistical purposes, a set of 163 proteins from the protein databank was randomly selected and a few specific cases are structurally analyzed and characterized in more detail. The results point that about 30%of the residues from each protein, on average, participate in ESS. Alternatively, for the specific cases considered,our results were based on the secondary structures produced after extensive Molecular Dynamics simulation of a protein–aqueous solvent system. Based on the very small width of the time distribution of the root mean squared deviations, between the ESS taken along the simulation and the ESS from the mean structure of the protein, for each ESS, we conclude that the ESSs significantly increase the conformational stability by forming very stable aggregates.The ubiquity and specificity of the ESS suggest that the role they play in the structure of proteins, including the domains formation, deserves to be thoroughly investigated. PMID:24513313

Degrève, Léo; Fuzo, Carlos A; Caliri, Antonio

2014-02-01

420

Cassegrain telescopes: limits of secondary movement in secondary focusing.  

PubMed

The maximum distance to which the secondary mirror can be moved with respect to its primary in a true Cassegrain telescope with limited image deterioration is found to be proportional to the fourth power of the focal ratio of the primary mirror. This limit is independent of all other parameters describing the system when the magnification of the secondary is greater than about 3. PMID:20165163

Clark, R N

1976-05-01

421

Targets and Secondary Beam Extraction  

NASA Astrophysics Data System (ADS)

Several applications make use of secondary beams of particles generated by the interaction of a primary beam of particles with a target. Spallation neutrons, bremsstrahlung photon-produced neutrons, radioactive ions and neutrinos are available to users at state-of-the-art facilities worldwide. Plans for even higher secondary beam intensities place severe constraints on the design of targets. This article reports on the main targetry challenges and highlights a variety of solutions for targetry and secondary beam extraction. Issues related to target station layout, instrumentation at the beam-target interface, safety and radioprotection are also discussed.

Noah, Etam

2014-02-01

422

Reactive transport modeling of CO2 mineral sequestration in basaltic rocks  

NASA Astrophysics Data System (ADS)

CO2 mineral sequestration in basalt may provide a long lasting, thermodynamically stable, and environmentally benign solution to reduce greenhouse gases in the atmosphere. Multi-dimensional, field scale, reactive transport models of this process have been developed with a focus on the CarbFix pilot CO2 injection in Iceland. An extensive natural analog literature review was conducted in order to identify the primary and secondary minerals associated with water-basalt interaction at low and elevated CO2 conditions. Based on these findings, an internally consistent thermodynamic database describing the mineral reactions of interest was developed and validated. Hydrological properties of field scale mass transport models were properly defined by calibration to field data using iTOUGH2. Reactive chemistry was coupled to the models and TOUGHREACT used for running predictive simulations carried out with the objective of optimizing long-term management of injection sites, to qu