Quartz grain microtextures of sediments from ODP Hole 188-1166A (Table 1)

This paper presents the results of the scanning electron microscopic (SEM) analysis of quartz grains from a selection of samples at Site 1166. Ocean Drilling Program Leg 188 drilled Site 1166 on the Prydz Bay continental shelf, Antarctica, to document onset and fluctuations of East-Antarctic glaciation. This site recovered Upper Pliocene-Holocene glacial sediments directly above Cretaceous through Lower Oligocene sediments recording the transition from preglacial to early glacial conditions. SEM analysis of quartz grains at Site 1166 was used to characterize the glacial and preglacial sediments by their diagnostic textures. Angular edges, edge abrasion as well as arcuate to straight steps, are the most frequent features in glacial deposits. The highest frequency of grains with round edges is present in Middle-Late Eocene fluvio-deltaic sands. However, angular outlines, fractured plates with subparallel linear fractures and edge abrasion indicating glacier influence are also present. Preglacial carbonaceous mudstone and laminated gray claystone show distinctive high relief quartz grains and some chemical weathering on grain surfaces. The results of the microtextural analysis of quartz grains are used to verify some critical periods of ice sheet evolution, such as the transition from the East Antarctic preglacial to glacial conditions on the continental shelf from Middle/Late Eocene to Late Eocene/Early Oligocene time.

Occurrence of microtextures recorded from quartz sand grains of ODP Hole 178-1101A (Table 1)

Sediment drifts on the continental rise are located proximal to the western side of the Antarctic Peninsula and recorded changes in glacial volume and thermal regime over the last ca. 15 m.y. At Ocean Drilling Program (ODP) Site 1101 (Leg 178), which recovered sediments back to 3.1 Ma, glacial-interglacial cyclicity was identified based on the biogenic component and sedimentary structures observed in X-radiographs, magnetic susceptibility and lithofacies descriptions. Glacial intervals are dominated by fine-grained laminated mud and interglacial units consist of bioturbated muds enriched in biogenic components. From 2.2 to 0.76 Ma, planktonic foraminifera and calcareous nannofossils dominate in the interglacials suggesting a shift of the Antarctic Polar Front (APF) to the south near the drifts. Prior to 2.2 Ma, cyclicity cannot be identified and diatoms dominate the biogenic component and high percent opal suggests warmer conditions south of the APF and reduced sea ice over the drifts. Analyses of the coarse-grained terrigenous fraction (pebbles and coarse sand) from Sites 1096 and 1101 record glaciers at sea-level releasing iceberg-rafted debris (IRD) throughout the last 3.1 m.y. Analyses of quartz sand grains in IRD with the scanning electron microscope (SEM) show an abrupt change in the frequency of occurrence of microtextures at ~1.35 Ma. During the Late Pliocene to Early Pleistocene, the population of quartz grains included completely weathered grains and a low frequency of crushing and abrasion, suggesting that glaciers were small and did not inundate the topography. Debris shed from mountain peaks was transported supraglacially or englacially allowing weathered grains to pass through the glacier unmodified. During glacial periods from 1.35-0.76 Ma, glaciers expanded in size. The IRD flux was very high and dropstones have diverse lithologies. Conditions resembling those at the Last Glacial Maximum (LGM) have been episodically present on the Antarctic Peninsula since ~0.76 Ma. Quartz sand grains show high relief, fracture and abrasion common under thick ice and the IRD flux is low with a more restricted range of dropstone lithologies.

A Mineralogical Study of a Dravitic Tourmaline from the Grenville Province

Tourmaline from a gem-quality deposit in the Grenville province has been studied with X-ray diffraction, visible-near infrared spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, electron microprobe and optical measurements. The tourmaline is found within tremolite-rich calc-silicate pods hosted in marble of the Central Metasedimentary Belt. The crystals are greenish-greyish-brown and have yielded facetable material up to 2.09 carats in size. Using the classification of Henry et al. 2011 the tourmaline is classified as a dravite, with a representative formula shown to be (Na0.73Ca0.2380.032)(Mg2+2.913Fe2+0.057Ti4+0.030) (Al3+5.787Fe3+0.017Mg2+0.14)(Si6.013O18)(BO3)3(OH)3((OH,O)0.907F0.093). Rietveld analysis of powder diffraction data gives a = 15.9436(8) Å, c = 7.2126(7) Å and a unit cell volume of 1587.8 Å3. A polished thin section was cut perpendicular to the c-axis of one tourmaline crystal, which showed zoning from a dark brown core into a lighter rim into a thin darker rim and back into lighter zonation. Through the geochemical data, three key stages of crystal growth can be seen within this thin section. The first is the core stage which occurs from the dark core to the first colourless zone; the second is from this colourless zone increasing in brown colour to the outer limit before a sudden absence of colour is noted; the third is a sharp change from the end of the second and is entirely colourless. These events are the result of metamorphism and hydrothermal fluids resulting from nearby felsic intrusive plutons. Scanning electron microscope, and electron microprobe traverses across this cross-section revealed that the green colour is the result of iron present throughout the system while the brown colour is correlated with titanium content. Crystal inclusions in the tourmaline of chlorapatite, and zircon were identified by petrographic analysis and confirmed using scanning electron microscope data and occur within the third stage of formation.

Analysis of Evidence from Core Sample Fractures in Stewardson Lake Uranium Prospect

This study was performed to characterize evidence of potential unconformity-type U mineralizing fluids in drill core fractures from the Stewardson Lake prospect, in the Athabasca Basin, located in Northern Saskatchewan and Alberta, Canada. Fractures were visually classified into eight varieties. This classification scheme was improved with the use of mineralogical characterization through SEM (Scanning Electron Microscope) and XRD analyses of the fracture fills and resulted in the identification of various oxides, hydroxides, sulfides, and clays or clay-sized minerals. Fractures were tallied to a total of ten categories with some commonalities in color. The oxidative, reductive or mixed nature of the fluids interacting with each fracture was determined based on its fill mineralogy. The measured Pb isotopic signature of samples was used to distinguish fractures affected solely by fluids emanating from a U mineralization source, from those affected by mixed fluids. Anomalies in U and U-pathfinder elements detected in fractures assisted with attributing them to the secondary dispersion halo of potential mineralization. Three types of fracture functions (chimney, composite and drain) were defined based on their interpreted flow vector and history. A secondary dispersion halo boundary with a zone of dominance of infiltrating fluids was suggested for two boreholes. The control of fill mineralogy on fracture color was investigated and the indicative and non-indicative colors and minerals, with respect to a secondary dispersion halo, were formally described. The fracture colors and fills indicative of proximity to the basement host of the potential mineralization were also identified. In addition, three zones of interest were delineated in the boreholes with respect to their geochemical dynamics and their relationship to the potential mineralization: a shallow barren overburden zone, a dispersion and alteration zone at intermediate depth, and a second deeper zone of dispersion and alteration.

BLOCK COPOLYMERS CONTAINING A LOW-SURFACE-ENERGY BLOCK AND THEIR APPLICATIONS

This thesis reports the synthesis and/or applications of three types of block copolymers that each bear a low-surface-energy block. First, poly(dimethylsiloxane)-block-poly(2-cinnamoyloxyethyl acrylate) (PDMS-b-PCEA) was synthesized and characterized. Cotton coating using a micellar solution of this block copolymer yielded superhydrophobic cotton fabrics. X-ray photoelectron spectroscopy (XPS) and surface property analyses indicated that the PDMS block topped the polymer coating. Photocuring the cotton swatches crosslinked the underlying PCEA layer and yielded permanent coatings. More interestingly, hydrophilically patterned superhydrophobic cotton fabrics were produced using photolithography that allowed the crosslinking of the coating around irradiated fibers but the removal, by solvent extraction, of the coating on fibers that were not irradiated. Since water-based ink only permeated the uncoated regions, such patterned fabric was further used to print ink patterns onto substrates such as fabrics, cardboard, paper, wood, and aluminum foil. Then, another PDMS-based diblock copolymer poly(dimethylsiloxane)-block-poly(glycidyl methacrylate) (PDMS-b-PGMA) was prepared. Different from PCEA that photocrosslinked around cotton fibers, PGMA reacted with hydroxyl groups on cotton fiber surfaces to get covalently attached. Further, different PGMA chains crosslinked with each other. PDMS-b-PGMA-coated cotton fabrics have been used for oil-water separations. In addition, polymeric nanoparticles were grafted onto cotton fiber surface before PDMS-b-PGMA was used to cover the surfaces of the grafted spheres and the residual surfaces of the cotton fibers. These two types of fabrics, coated by the block copolymer alone or by the polymer nanospheres and then the copolymer, were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and water repellency analyses. A comprehensive comparative study was made of their performances in oil-water separation. Finally, a fluorinated ABC triblock copolymer poly(acrylic acid)-block-poly(2-cinnamoyloxyethyl methacrylate)-block-poly(2-perfluorooctylethyl methacrylate) (PAA-b-PCEMA-b-PFOEMA) was used to iii encapsulate air nanobubbles. The produced air nanobubbles were thermodynamically stable in water and were some 100 times more stable than commercially available perfluorocarbon-filled microbubbles under ultrasound. These nanobubbles, due to their small sizes and thus ability to permeate the capillary networks of organs and to reach tumors, may expand the applications of microbubbles in diagnostic ultrasonography and find new applications in ultrasound-regulated drug delivery.

Heavy Minerals in Soils from the Athabasca Basin and the Implications for Exploration Geochemistry of Uranium Deposits at Depth

The Centennial deposit is a high grade (~8% U3O8), deeply buried (~950m), unconformity-related U deposit located in the south-central region of the Athabasca Basin in northern Saskatchewan, Canada. The mineral chemistry of fine fractions (<63 μm) of soils from grids above the Centennial deposit were examined to understand possible controls on the geochemistry and radiogenic 207Pb/206Pb ratios measured in the clay-size (<2 μm) fractions used for exploration. Soil samples distal and proximal to the deposit projection to the surface and geophysically defined structures were selected. Mineral abundances were determined using the scanning electron microscope and Mineral Liberation Analysis. Zircon was the only U-rich mineral identified with modal abundances >0.02% by weight. Monazite, which can be U-rich, was identified, but not in significant abundances. The source of the zircon and other heavy minerals is interpreted to be from sub-cropping sources that are >100 km up-ice from Centennial. Trace element analysis using laser ablation inductively coupled plasma mass spectrometry of hydroseparated zircon grains indicate that zircon abundances and zircon Pb concentrations in surficial samples have minimal effect on the radiogenic 207Pb/206Pb ratios in the clay-fraction of the samples, with the dominant source of radiogenic Pb being clay mineral surfaces that trapped Pb during secondary dispersion from the Centennial uranium deposit through faults and fractures to the surface. The REE patterns indicate HREE enrichment in the clay-fractions of samples that have higher abundances of zircon in the <20 μm fraction. Immobile elements such as HREE that are concentrated in zircon can be used as indicators of radiogenic Pb being sourced from minerals at the surface rather than being sourced from secondary dispersion from deeply buried U deposits.

Improved electrochemical performance of Sr2Fe1.5Mo0.4Nb0.1O6-δ -Sm0.2Ce0.8O2-δ composite cathodes by a one-pot method for intermediate temperature solid oxide fuel cells

In this paper, Sr₂Fe_1.5Mo_0.4Nb_0.1O_6-δ (SFMNb)-xSm_0.2Ce_0.8O_2-δ (SDC) (x = 0, 20, 30, 40, 50 wt%) composite cathode materials were synthesized by a one-pot combustion method to improve the electrochemical performance of SFMNb cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). The fabrication of composite cathodes by adding SDC to SFMNb is conducive to providing extended electrochemical reaction zones for oxygen reduction reactions (ORR). X-ray diffraction (XRD) demonstrates that SFMNb is chemically compatible with SDC electrolytes at temperature up to 1100 °C. Scanning electron microscope (SEM) indicates that the SFMNb-SDC composite cathodes have a porous network nanostructure as well as the single phase SFMNb. The conductivity and thermal expansion coefficient of the composite cathodes decrease with the increased content of SDC, while the electrochemical impedance spectra (EIS) exhibits that SFMNb-40SDC composite cathode has optimal electrochemical performance with low polarization resistance (R_p) on the La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ electrolyte. The R_p of the SFMNb-40SDC composite cathode is about 0.047 Ω cm² at 800 °C in air. A single cell with SFMNb-40SDC cathode also displays favorable discharge performance, whose maximum power density is 1.22 W cm^-2 at 800 °C. All results indicate that SFMNb-40SDC composite material is a promising cathode candidate for IT-SOFCs.

A new technique to automatically quantify microstructures of fine grained carbonate mylonites: two-step etching combined with SEM imaging and image analysis

A two-step etching technique for fine-grained calcite mylonites using 0.37% hydrochloric and 0.1% acetic acid produces a topographic relief which reflects the grain boundary geometry. With this technique, calcite grain boundaries become more intensely dissolved than their grain interiors but second phase minerals like dolomite, quartz, feldspars, apatite, hematite and pyrite are not affected by the acid and therefore form topographic peaks. Based on digital backscatter electron images and element distribution maps acquired on a scanning electron microscope, the geometry of calcite and the second phase minerals can be automatically quantified using image analysis software. For research on fine-grained carbonate rocks (e.g. dolomite calcite mixtures), this low-cost approach is an attractive alternative to the generation of manual grain boundary maps based on photographs from ultra-thin sections or orientation contrast images.

Atividade β-D-N-Acetilglucosaminidásica de enzimas imobilizadas extraídas da Artemia franciscana e possíveis aplicações biotecnológicas

A β-D-N-acetilglucosaminidase extracted and partially isolated from crustacean Artemia franciscana by ammonium sulfate precipitation and filtration gel chromatography Bio Gel A 1.5m. the enzyme was immobilized on ferromagnetic Dacron yielding a insoluble active derivative with 5.0 units/mg protein and 10.35% of the soluble enzyme activity. β-D-N-acetilglucosaminidase-ferromagnetic Dacron was easily removed from the reaction mixture by a magnetic field, it was reused for ten times without loss in its activity. The ferromagnetic Dacron was better activated at pH 5.0. The particles visualized at scanning electron microscope (SEM) had presented different sizes, varying between 721nm and 100µm. Infra red confirmed immobilization on support, as showed by primary amino peaks at 1640 and 1560 cm-1 . The immobilize enzyme presented Km of 2.32 ± 0.48 mM and optimum temperature of 50°C. Bought presented the same thermal stable of the soluble enzyme and larger enzymatic activity at pH 5.5. β-D-N-acetilglucosaminidase-Dacron ferromagnético showed sensible for some íons as the silver (AgNO3), with loss of activity. The β-D-N acetilglucosaminidase activity for mercury chloride (HgCl2), whom is one of the most toxic substance joined in nature, it was presented activity already diminished at 0,01mM and lost total activity at 4mM, indicating sensitivity for this type of metal. β-D-N-acetilglucosaminidase-ferromagnetic Dacron showed degradative capacity on heparan sulfate, the enzyme still demonstrated degradative capacity on heparan sulphate, suggesting a possible application to produce fractions of this glycosaminoglycan

Preparation of Ni-P electroless and its corrosion resistance against sea water

Electroless coating is much appropriate process at engineering surface. Since the discovery of electroless nickel-phosphorus coating in 3996, due to technical and economic advantages as well as desirable characteristics such as resistance to corrosion, abrasion and a high hardness has found wide application at engineering industries. Properties of electroless nickel-phosphorus coating depend on the characteristics of the used bath and heat treatment. In this study, optimal conditions and concentration of sodium citrate, sodium acetate and lactic acid in the bath of electroless nickel-phosphorus coating to the steel ck67 surface was determined. Structure, chemical composition and phases occurring in the coating were investigated using Scanning Electron Microscope (SEM) and X-ray diffraction analysis (XRD). The corrosion behavior of coatings in solution 3.5٪ NaCl was studied using electrochemical. The results showed that corrosion resistance of the coating with composition sodium citrate, sodium acetate and lactic acid decreased respectively.

Application of chitosan loaded with metal oxide nano particles to remove lead present from sea water

Chitosan is a natural polymer obtained by deacetylation of chitin. After cellulose chitin is the second most abundant polysaccharide in nature. It is biologically safe, non-toxic, biocompatible and biodegradable polysaccharide. Chitosan loaded with zinc oxide nanoparticles have gained more attention bio sorbent because of their better stability, low toxicity, simple and mild preparation method and high sorption capacity. Chitosan loaded with zinc oxide nanoparticles have been prepared of chitosan. The physicochemical properties of nanoparticles were characterized by Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM) Analysis. Its sorption capacity for lead and cadmium ions studied. Factors such as initial concentration of lead ions, cadmium ions sorbent amount, contact time, pH and temperature were investigated. It is found that chitosan loaded with zinc oxide nanoparticles could sorb lead and cadmium ions effectively, this sorption rate was affected significantly by initial concentration of lead and cadmium ions, sorbent amount, contact time, pH of solution. The maximum of percentage of lead sorption was 98 % with initial concentration 3 mg/l and sorbent amount 0.05 g, pH 11 in 45 min and cadmiumwas90 %with initial concentration 3mg/l and sorbent amount 0.05 g, pH 11 in45 min. Consequently chitosan loaded with zinc oxide nanoparticles demonstrated greater fixation ability for lead ions than cadmium ions.

Fabrication and optimizing of metal nano silicate as toxic metal absorbent from sea water

Pure Water, is a crucial demand of creature life. Following industrial development, extra amount of toxic metals such as chromium enters the environmental cycle through the sewage, which is considered as a serious threat for organisms. One of the modern methods of filtration and removal of contaminants in water, is applying Nano-technology. According to specific property of silicate materials, in this article we try to survey increased power in composites and various absorption in several morphologies and also synthesis of Nano-metal silicates with different morphologies as absorbent of metal toxic ions. At first, we synthesize nano zink silicate with three morphologies considering context and the purpose of this survey. 1) Nano synthesis of zink silicate hollow cavity by hydrothermal method in mixed solvent system of ethanol/glycol polyethylene. 2) Zink nano wires silicate in a water-based system by controlling the amount of sodium silicate. 3) Synthesis of nano zink silicate membrane. After synthesizing, we measured the cadmium ion absorbance by synthesized nano zink silicates. Controlling PH, is the applied absorption method. Next step, we synthesized nano zink-magnesium silicate composite in two various morphologies of nanowires and membrane by different precent of zink and magnesium, in order to optimize synthesized nano metal silicate. We used zink nitrate and magnesium nitrate and also measured cadmium absorption by synthesized nano metal silicates in the same way of PH control absorption. In the 3rd step, in order to determine the impact of the type of metal in nano metal silicate, we synthesized nano magnesium silicate and compared its absorption with nano zink silicate. Furthermore, we calculated the optimal concentration in one of synthesizes. Optimal concentration is the process which has the maximum absorption. While applying two methods of absorption in the test, finally we compared the effect of absorption method on the absorption level. Below you find further steps of synthesis: 1) Using IR, RAMAN, XRD spectroscopy to check the accuracy of synthesis. 2) Checking the dispersion of nano particles in ethanol solution by light microscope. 3) Measuring and observing particles with scanning electron microscope (SEM). 4) Using atomic absorption device for measuring the cadmium concentration in water-based solutions. The nano metal silicates were synthesized successfully. All of synthesized nano absorbents have the cadmium ion absorbency. The cadmium absorption via nano absorbents depend on various factors such as kind of metal in nano silicate and percent of metal in nano metal silicate composite. Meanwhile the absorption and PH control of medium containing the absorbent and solution would affect the cadmium absorption.

Influência da gipsita no surgimento de eflorescência em telhas cerâmicas

The red ceramic industry is recognized as of major importance in Piauí State. The State capital, Teresina, is the greatest producer of this material ( production about 18 million peaces), which is used mainly for masonry sealing blocks. One of the most frequent problems in this kind of products is the efflorescence. This work has the main objective of studying the influence of gypsum addition on non-glazed tiles, by using the local industry production standards. The raw materials were characterized by FRX, DRX, TGA, DTA and AD. Extruded test specimens were made with the addition of 1, 3 and 5% of gypsum in the ceramic paste, burned at 850oC, 950oC and 1050oC and submitted to further technological tests and microestrutural analysis by the scanning electron microscope. In order to accelerate the aging of bodies of evidence, they were immersed in successive water baths and posterior drying. The reference ceramic paste showed tendency to efflorescence formation after drying and consolidated efflorescence after burning, but no affecting the technological results