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Sample records for subangular quartz grains

  1. Surface Textural Analysis of Quartz Grains from Modern Point Bar Deposits in Lower Reaches of the Yellow River

    Science.gov (United States)

    Cheng, Yong; Liu, Cong; Lu, Ping; Zhang, Yu; Nie, Qi; Wen, Yiming

    2018-01-01

    The surfaces of quartz grains contain characteristic textures formed during the process of transport, due to their stable physical and chemical properties. The surface textures include the information about source area, transporting force, sedimentary environment and evolution history of sediment. Surface textures of quartz grains from modern point bar deposits in the lower reaches of the Yellow River are observed and studied by scanning electron microscopy (SEM). Results indicate that there are 22 kinds of surface textures. The overall surface morphology of quartz grains shows short transporting time and distance and weak abrasive action of the river water. The combined surface textures caused by mechanical action indicate that quartz grains are transporting in a high-energy hydrodynamic condition and suffer a strong mechanical impact and abrasion. The common solution pits prove that the chemical property of transportation medium is very active and quartz grains receive an obvious chemical action. The combination of these surface textures can be an identification mark of fluvial environment, and that is: quartz grains are main subangular outline, whose roundness is higher with the farther motion distance; Surface fluctuation degree of quartz grains is relatively high, and gives priority to high and medium relief; V-shaped percussion marks are very abundant caused by mechanical action; The conchoidal of different sizes and steps are common-developed with paragenesis relationship; Solution pits are common-developed as well. The study makes up for the blank of surface textures analysis of quartz grains from modern fluvial deposits in China. It provides new ideas and evidence for studies of the sedimentary process and environmental significance, although the deep meanings of these micro textures remain to be further researched.

  2. Micromorphological difference between glacial and glaciofluvial quartz grain, evidence from Svalbard

    Science.gov (United States)

    Krbcová, Klára

    2017-04-01

    Micromorphology of glaciofluvial sediments were only partially shown by Mahaney et al. (2001). This paper deals with the main diagnostic textures of glaciofluvial sediments and changes of their micromorphology caused fluvial transport. All samples were collected in Svalbard in August 2012. Two glacial samples and six glaciofluvial samples were taken near the glacier Bertilbreen and one glacial sample and seven glaciofluvial samples were taken near the glacier Hørbyebreen. Samples were prepared according to the Mahaney (2002) and examined under electron microscope. The correlation analyses was used to set the main glaciofluvial microtextures. Similarity of the samples was tested by one-way ANOVA by F-test. Increasing numbers of V-shaped pits, rounded grains, meandering ridges and microblocks are typical for characteristic microtextures of glaciofluvial grains which had greater rate of fluvial transport. But the grains mainly transported by glacier had a greater percentage occurence of subangular grains, straight steps, straight and curved grooves, adhering particles, pitting and V-shaped etch pits. The fastest change in variability was set during the first kilometre of fluvial transport. The study was funded by the Grant Agency of Charles University (GAUK 1314214). Keywords: exoscopy, quartz grains micromorphology, glaciofluvial sediments References: MAHANEY, W. C. (2002): Atlas of sand grain surface textures and applications. Oxford University Press, USA, 237 s. MAHANEY, W. C., STEWART A., KALM, V. (2001): Quantification of SEM microtextures useful in sedimentary environmental discrimination. Boreas, 30, s. 165 - 171.

  3. The recrystallized grain size piezometer for quartz

    Science.gov (United States)

    Stipp, Michael; Tullis, Jan

    2003-11-01

    In order to determine a recrystallized grain size piezometer for quartz, we deformed Black Hills quartzite in a molten salt assembly in a Griggs apparatus at 1.5 GPa, 800 to 1100°C, and strain rates between 2*10-7 and 2*10-4 s-1, conditions which include dislocation creep regimes 2 and 3 of Hirth and Tullis [1992]. Flow stresses ranged from 34 +/- 16 to 268 +/- 38 MPa with corresponding recrystallized grain sizes from 46 +/- 15 to 3.2 +/- 0.7 μm. The data are well fit by a single piezometer relation, D = 103.56+/- 0.27 * σ-1.26 +/- 0.13, with no change in slope at the regime 2-3 transition and no effect of temperature or α/β stability field. Another experimental piezometer relation for regime 1 of Hirth and Tullis [1992] differs in slope, suggesting that different recrystallization mechanisms require different piezometer calibrations.

  4. Dosimetric properties of natural quartz grains extracted from fired materials

    DEFF Research Database (Denmark)

    Bluszcz, A.; Bøtter-Jensen, L.

    1995-01-01

    The paper describes an examination of the dosimetric properties of natural quartz grains extracted from ancient fired materials. Eleven samples of different origin were tested for their TL and GLSL (green light stimulated luminescence) sensitivities within the mGy dose range. Very promising results...... were obtained showing the possibility of measuring the doses of around 10 mGy with 1% precision using GLSL or TL and using the single aliquot technique for natural quartz as a dosimeter. The lowest detectable dose was estimated to be lower than 500 mu Gy. The results obtained indicate that natural...... quartz grains from selected materials could be used for the dosimetry of environmental gamma radiation for the purposes of paleodosimetric dating methods as well as for accident dosimetry....

  5. Transitional grain-size-sensitive flow of milky quartz aggregates

    Science.gov (United States)

    Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

    2014-12-01

    Fine-grained (~15 μm) milky quartz aggregates exhibit reversible flow strengths in triaxial compression experiments conducted at T = 800-900oC, Pc = 1.5 GPa when strain rates are sequentially decreased (typically from 10-3.5 to 10-4.5 and 10-5.5 s-1), and then returned to the original rate (10-3.5 s-1), while samples that experience grain growth at 1000oC (to 35 μm) over the same sequence of strain rates exhibit an irreversible increase in strength. Polycrystalline quartz aggregates have been synthesized from natural milky quartz powders (ground to 5 μm) by HIP methods at T = 1000oC, Pc = 1.5 GPa and t = 24 hours, resulting in dense, fine-grained aggregates of uniform water content of ~4000 ppm (H/106Si), as indicated by a broad OH absorption band at 3400 cm-1. In experiments performed at 800o and 900oC, grain sizes of the samples are essentially constant over the duration of each experiment, though grain shapes change significantly, and undulatory extinction and deformation lamellae indicate that much of the sample shortening (to 50%) is accomplished, over the four strain-rate steps, by dislocation creep. Differential stresses measured at T = 800oC decrease from 160 to 30 MPa as strain rate is reduced from 10-4.6 to 10-5.5 s-1, and a stress of 140 MPa is measured when strain rate is returned to 10-4.5 s-1. Samples deformed at 1000o and 1100oC experience normal grain growth, with grain boundary energy-driven grain-coarsening textures superposed by undulatory extinction and deformation lamellae. Differential stresses measured at 1000oC and strain rates of 10-3.6, 10-4.6, and 10-5.5 s-1 are 185, 80, and 80 MPa, respectively, while an increased flow stress of 260 MPa is measured (following ~28 hours of prior high temperature deformation and grain growth) when strain rate is returned to 10-3.6 s-1. While all samples exhibit lattice preferred orientations, the stress exponent n inferred for the fine-grained 800oC sample is 1.5 and the stress exponent of the coarse-grained

  6. Charge movement in grains of quartz studied using exo-electron emission

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Denby, Phil M.; Murray, A.S.

    2008-01-01

    movement in luminescence phosphors. Here we show that OSE from natural quartz grains gives an easily detectable, reproducible and light sensitive signal, although it is not as intense as OSL. A single sample of natural quartz grains extracted from a sediment is used to investigate the thermal stability...

  7. Optical dating of single sand-sized grains of quartz: Sources of variability

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.; Murray, A.S.

    2000-01-01

    Optically stimulated luminescence (OSL) measurements have been made of over 3000 sand-sized grains of quartz. Analysis at this scale highlights the variability in the luminescence sensitivity and the dose saturation characteristics of individual quartz grains. Using a new instrument capable of me...... intensity, dose saturation characteristics and instrument uncertainty in equivalent dose calculation. (C) 2000 Elsevier Science Ltd. All rights reserved....

  8. Control of Montmorillonite Surface Coatings on Quartz Grains in Bentonite by Precursor Volcanic Glass

    Science.gov (United States)

    Wendlandt, R. F.; Harrison, W. J.

    2008-12-01

    The pathogenic tendencies of respirable-sized quartz grains may be dependent on inherent characteristics of the quartz as well as external factors. Surface coatings on quartz are of particular interest as they modify both physical and chemical properties of quartz grain surfaces and sequester the grain from contact with reactive lung fluids. Wendlandt et al. (Appl. Geochem. 22, 2007) investigated the surface properties of respirable-sized quartz grains in bentonites and recognized pervasive montmorillonite surface coatings on the quartz that resisted removal by repeated vigorous washings and reaction with HCl. To understand the persistence of montmorillonite coatings on quartz grains of igneous origin, volcanic ash deposits of varying age and degree of alteration to montmorillonite were sampled in Utah, including the distal Lava Creek (c. 0.64 Ma) and Bishop Tuffs (c. 0.74 Ma), and SW Colorado (Conejos Fm, San Juan Volcanic Field) for comparison with commercial grade Cretaceous-age "western" and "southern" bentonites. Quartz grains, hand-picked from these samples, were analyzed using FE-SEM and HRTEM. Continuous coatings of volcanic glass occur on quartz grains from the distal volcanic ash samples. As glass alteration to montmorillonite becomes more extensive, quartz grain surfaces start to display patches of montmorillonite. These patches become continuous in extent on quartz grains from the bentonites. Late precipitation of opal- CT lepispheres is consistent with the alteration reaction for volcanic glass: Volcanic glass + H2O = montmorillonite + SiO2(am) + ions(aq). HRTEM of quartz grains reveals an amorphous surface layer, consistent with a volcanic glass coating. Our results indicate that persistent montmorillonite coatings on quartz grains in bentonites are related to precursor volcanic glass coatings on these grains. The absence of glass coatings on other mineral grains in bentonite (feldspar, biotite) may be a consequence of the presence of strong cleavage

  9. Identification of the volcanic quartz origins from dune sand using a single-grain RTL measurement

    Science.gov (United States)

    Yawata, Takashi; Hashimoto, Tetsuo

    2004-05-01

    In an earlier study, we found that quartz grains extracted from Niigata dune sand all contained red thermoluminescence (RTL) phenomena. This RTL could subsequently be attributed to the volcanic origin of the material. The Agano River is assumed to be the main source of the Niigata dune material. Using the single aliquot regenerative method, which involves the measurement of several hundreds of grains, the measured equivalent doses from the RTL-quartz grains were larger than expected. Consequently, a single-grain method combined with RTL-measurement was developed to determine the equivalent doses from each quartz grain. Placing a biotite plate with a central hole for the sample grain on the sample disk made a significant contribution to keeping background levels as low as possible. The histogram of the equivalent doses evaluated from 72 quartz grains revealed that the Niigata dune originates from at least four different volcanic sources around Agano River. One of them is the Numazawa volcano, because the minimum equivalent dose values from the single grain method are equal to those of quartz grains from the Numazawa pumice.

  10. Optically stimulated luminescence techniques in retrospective dosimetry using single grains of quartz extracted from unheated materials

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov

    dosimetry). Special attention has been paid to quartz extracted from unheated building materials such as concrete and mortar. The single-aliquot regeneration-dose (SAR) protocol has been used to determine absorbeddoses in small aliquots as well as single grains of quartz. It is shown that OSL measurements...

  11. The preservation of quartz grain surface textures following vehicle fire and their use in forensic enquiry.

    Science.gov (United States)

    Morgan, R M; Little, M; Gibson, A; Hicks, L; Dunkerley, S; Bull, P A

    2008-09-01

    During a terrorist trial, dispute arose as to whether the temperature produced in a car fire was sufficient to destroy quartz grain surface textures. A series of seven sequential experiments showed that the temperature for quartz surface texture modification/destruction and the production of vugs, vesicles and glassy precipitation ('snowdrifting') occurred at 1200 degrees C under normal atmospheric conditions. By adding a number of man-made and natural substances, it was found that only the presence of salts depressed this modification temperature (to 900 degrees C). Experiments to determine the temperature of fire in a car indicated that the maximum temperature produced under natural conditions (810 degrees C) was insufficient to affect the quartz grain surface textures. These results confirm the use of surface texture analysis of quartz grains recovered from the remains of cars subjected to fire and their use as a forensic indicator.

  12. Thermal activation of OSL as a geothermometer for quartz grain heating during fault movements

    CERN Document Server

    Rink, W J; Rees-Jones, J; Schwarcz, H P

    1999-01-01

    In discussions of ESR dating of fault movements, there has been much debate whether zeroing of ESR signals is a mechanical shearing effect or caused by frictional heating. The OSL (optically stimulated luminescence) sensitivity of quartz is known to increase after heating. This thermal activation of dose response of the OSL in quartz should be useful as a geothermometer to test whether quartz particles in fault gouge had been heated. We tested the OSL sensitivities of quartz from fault gouge, and from a control (quartz grains from sandstone) and were able to show heat-induced enhancement of OSL sensitivity to a test dose. We observed that relative enhancement of OSL dose response (ratio of heated to unheated single aliquots) is significantly less for the finest grains (45-75 and 100-150 mu m) compared with coarser grains (150-250 mu m). These data are consistent with a model of zeroing of the quartz grains during faulting, by frictional heating localized to the grain boundaries, which would be expected to aff...

  13. LM-OSL from single grains of quartz: A preliminary study

    DEFF Research Database (Denmark)

    Bulur, E.; Duller, G.A.T.; Solongo, S.

    2002-01-01

    The recently developed single grain attachment for the Riso TL-OSL reader has been modified to achieve linearly modulated optically stimulated luminescence (LM-OSL). Three different types of luminescence behaviour were observed in 81 quartz grains measured. These types are those showing only the ...

  14. Dating ice shelf edge marine sediments: A new approach using single-grain quartz luminescence

    DEFF Research Database (Denmark)

    Berger, G.W.; Murray, A.S.; Thomsen, Kristina Jørkov

    2010-01-01

    the Antarctic Peninsula, sediment-water-interface (“zero-age” analogs), silt-rich short cores were collected in 2001–2003, originally only for fine silt dating tests. Later access to suitable instrumentation also permitted testing the potential of single-grain quartz (SGQ) dating of sand grains from these cores...... should employ large-diameter coring devices (e.g., Kasten and multicorers). A caveat is that large numbers (e.g., ∼10,000) of quartz grains may need analysis to provide acceptable statistics for useful age calculations....

  15. Investigation of quartz grain surface textures by atomic force microscopy for forensic analysis.

    Science.gov (United States)

    Konopinski, D I; Hudziak, S; Morgan, R M; Bull, P A; Kenyon, A J

    2012-11-30

    This paper presents a study of quartz sand grain surface textures using atomic force microscopy (AFM) to image the surface. Until now scanning electron microscopy (SEM) has provided the primary technique used in the forensic surface texture analysis of quartz sand grains as a means of establishing the provenance of the grains for forensic reconstructions. The ability to independently corroborate the grain type classifications is desirable and provides additional weight to the findings of SEM analysis of the textures of quartz grains identified in forensic soil/sediment samples. AFM offers a quantitative means of analysis that complements SEM examination, and is a non-destructive technique that requires no sample preparation prior to scanning. It therefore has great potential to be used for forensic analysis where sample preservation is highly valuable. By taking quantitative topography scans, it is possible to produce 3D representations of microscopic surface textures and diagnostic features for examination. Furthermore, various empirical measures can be obtained from analysing the topography scans, including arithmetic average roughness, root-mean-square surface roughness, skewness, kurtosis, and multiple gaussian fits to height distributions. These empirical measures, combined with qualitative examination of the surfaces can help to discriminate between grain types and provide independent analysis that can corroborate the morphological grain typing based on the surface textures assigned using SEM. Furthermore, the findings from this study also demonstrate that quartz sand grain surfaces exhibit a statistically self-similar fractal nature that remains unchanged across scales. This indicates the potential for a further quantitative measure that could be utilised in the discrimination of quartz grains based on their provenance for forensic investigations. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. Quartz grains reveal sedimentary palaeoenvironment and past storm events: A case study from eastern Baltic

    Science.gov (United States)

    Kalińska-Nartiša, Edyta; Stivrins, Normunds; Grudzinska, Ieva

    2018-01-01

    Sediment record collected from the coastal lake serves as a powerful tool for reconstructing changes in palaeoenvironment and understanding the potential signals of past storminess. In this study, we use several proxies from sediment of the Holocene Thermal Maximum at coastal Lake Lilaste, Latvia. We focus on surface texture of quartz grains from the mineral inorganic fraction as indicators of depositional environments. We then use this as a proxy for potential storm transport and combine with information on granulometry, diatom stratigraphy and chronology to answer the question whether flux of quartz grains in the lake originated from the sea or from the land. Analyses in a binocular and scanning electron microscope reveal that most of the investigated quartz grains originate from dwelling in the seawater and wave action in the nearshore zone. Grains representing very energetic subaqueous environment similar to storm events are also present. Terrestrial record is of minor significance and visible through occurrence of aeolian quartz grains. During drier and colder conditions, an influx of sand with aeolian imprint was delivered to the lake between 8500 and 7800 cal yr BP. Marine and terrestrial conditions alternated between 7800 and 6000 cal yr BP. Storm-induced grains were likely deposited three times: at 7300 cal yr BP, 6600-6400 cal yr BP, and 6200-6000 cal yr BP. Overall stable marine environmental conditions prevailed between 6000 and 4000 cal yr BP except of the last portion of terrestrial-induced sediment at 4100 cal yr BP.

  17. OSL dating of fine-grained quartz from Holocene Yangtze delta sediments

    DEFF Research Database (Denmark)

    Sugisaki, Saiko; Buylaert, Jan-Pieter; Murray, Andrew

    2015-01-01

    sediment cores (YD13-G3 and H1) were taken from the Yangtze subaqueous delta to investigate precipitation history. In this study, we investigate the potential of quartz OSL dating of the fine silt fraction (fine-grained quartz; 4-11 μm) from these cores to estimate the depositional age of the sediments. We...... test whether: (1) Yangtze subaqueous delta sediments contain quartz with suitable characteristics for dating, and (2) quartz grains are well-bleached during/before the transportation process, by examining a modern analogue of suspended particulate matter, and by cross-checking with the doses derived...... from infrared stimulated luminescence (IRSL) signals (both IR50 and pIRIR160) from feldspar in polymineral fine grains. We find that both the quartz and feldspar luminescence characteristics are satisfactory (quartz dose recovery ratio 1.067 ± 0.004; n = 250, pIRIR160 dose recovery ratio 1.01 ± 0.02; n...

  18. Mineralogy, morphology, and textural relationships in coatings on quartz grains in sediments in a quartz-sand aquifer

    Science.gov (United States)

    Zhang, Shouliang; Kent, Douglas B.; Elbert, David C.; Shi, Zhi; Davis, James A.; Veblen, David R.

    2011-01-01

    Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily impacted by wastewater discharge shows similar coating textures and chemical compositions. Major constituents of the coating include Al-substituted goethite and illite/chlorite clays. Goethite is aggregated into well-crystallized domains through oriented attachment resulting in increased porosity. Illite/chlorite clays with various chemical compositions were observed to be mixed with goethite aggregates and aligned sub-parallel to the associated quartz surface. The uniform spatial distribution of wastewater-derived phosphorus throughout the coating from the wastewater-contaminated site suggests that all of the coating constituents, including those adjacent to the quartz surface, are accessible to groundwater solutes. Both TEM characterization and chemical extraction results indicate there is a significantly greater amount of amorphous iron oxide in samples from wastewater discharge area compared to those from the pristine region, which might reflect the impact of redox cycling of iron under the wastewater-discharge area. Coating compositions are consistent with the moderate metal and oxy-metalloid adsorption capacities, low but significant cation exchange capacities, and control of iron(III) solubility by goethite observed in reactive transport

  19. Mineralogy, morphology, and textural relationships in coatings on quartz grains in sediments in a quartz-sand aquifer.

    Science.gov (United States)

    Zhang, Shouliang; Kent, Douglas B; Elbert, David C; Shi, Zhi; Davis, James A; Veblen, David R

    2011-06-01

    Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily impacted by wastewater discharge shows similar coating textures and chemical compositions. Major constituents of the coating include Al-substituted goethite and illite/chlorite clays. Goethite is aggregated into well-crystallized domains through oriented attachment resulting in increased porosity. Illite/chlorite clays with various chemical compositions were observed to be mixed with goethite aggregates and aligned sub-parallel to the associated quartz surface. The uniform spatial distribution of wastewater-derived phosphorus throughout the coating from the wastewater-contaminated site suggests that all of the coating constituents, including those adjacent to the quartz surface, are accessible to groundwater solutes. Both TEM characterization and chemical extraction results indicate there is a significantly greater amount of amorphous iron oxide in samples from wastewater discharge area compared to those from the pristine region, which might reflect the impact of redox cycling of iron under the wastewater-discharge area. Coating compositions are consistent with the moderate metal and oxy-metalloid adsorption capacities, low but significant cation exchange capacities, and control of iron(III) solubility by goethite observed in reactive transport

  20. On the importance of grain size in luminescence dating using quartz

    DEFF Research Database (Denmark)

    Timar-Gabor, A.; Buylaert, Jan-Pieter; Guralnik, B.

    2017-01-01

    -grain (63-90 μm) quartz single aliquot regeneration protocol (SAR) ages has been reported previously for Romanian and Serbian loess >40 ka (De of ∼100 Gy), generally with fine-grain ages underestimating the depositional age. In this paper, we show a similar age pattern for two grain size fractions from...... the dose response curves of quartz from different sedimentary contexts around the world, using a range of grain sizes (diameters of 4-11 μm, 11-30 μm, 35-50 μm, 63-90μm, 90-125μm, 125-180 μm, and 180-250 μm). All dose response curves can be adequately described by a sum of two saturating exponential...

  1. Optically stimulated luminescence techniques in retrospective dosimetry using single grains of quartz extracted from unheated materials

    Energy Technology Data Exchange (ETDEWEB)

    Joerkov Thomsen, Kristina

    2004-02-01

    This work investigates the possibility of applying optically stimulated luminescence (OSL) in retrospective dose determinations using unheated materials. It focuses on identifying materials suitable for use in assessment of doses absorbed as a consequence of radiation accidents (i.e. accident dosimetry). Special attention has been paid to quartz extracted from unheated building materials such as concrete and mortar. The single-aliquot regeneration-dose (SAR) protocol has been used to determine absorbed doses in small aliquots as well as single grains of quartz. It is shown that OSL measurements of single grains of quartz extracted from poorly-bleached building materials can provide useful information on radiation accident doses, even when the luminescence sensitivity is low. Sources of variance in well-bleached single grain dose distributions have been investigated in detail and it is concluded that the observed variability in the data is consistent with the sum (in quadrature) of a component, which depends on the number of photons detected from each grain, and a fixed component independent of light level. Dose depth profiles through laboratory irradiated concrete bricks have successfully been measured and minimum detection limits of less than 100 mGy are derived. Measurements of thermal transfer in single grains of poorly-bleached quartz show that thermal transfer is variable on a grain-to-grain basis and that it can be a source of variance in single-grain dose distributions. Furthermore, the potential of using common household and workplace chemicals, such as table salt, washing powder and water softener, in retrospective dosimetry has been investigated. It is concluded that such materials should be considered as retrospective dosimeters in the event of a radiation accident. (au)

  2. Determination of burial dose in incompletely bleached fluvial samples using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, Lars

    2007-01-01

    We determine the burial dose in three known-age incompletely bleached fluvial samples using single grains of quartz. Estimation of burial dose in incompletely bleached samples requires that the characteristics of the well-bleached part of the distribution are known in order to distinguish between...

  3. Sources of variability in OSL dose measurements using single grains of quartz

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, A.S.; Bøtter-Jensen, L.

    2005-01-01

    spread. In this preliminary study, dose distributions have been studied using single grains of heated and laboratory irradiated quartz. By heating the sample, the contribution from incomplete zeroing was excluded and at the same time the sample was sensitised. The laboratory gamma irradiation...

  4. The dose dependency of the over-dispersion of quartz OSL single grain dose distributions

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, Andrew S.; Jain, Mayank

    2012-01-01

    The use of single grain quartz OSL dating has become widespread over the past decade, particularly with application to samples likely to have been incompletely bleached before burial. By reducing the aliquot size to a single grain the probability of identifying the grain population most likely...... to have been well-bleached at deposition is maximised and thus the accuracy with which the equivalent dose can be determined is – at least in principle – improved. However, analysis of single grain dose distributions requires knowledge of the dispersion of the well-bleached part of the dose distribution...... also show that the dim grains in the distributions have a greater over-dispersion than the bright grains, implying that insensitive samples will have greater values of over-dispersion than sensitive samples....

  5. Stress distribution during cold compression of a quartz aggregate using synchrotron X-ray diffraction: Observed yielding, damage, and grain crushing: STRESS DISTRIBUTION OF QUARTZ AGGREGATE

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, C. S. N. [Mineral Physics Institute, Stony Brook University, Stony Brook New York USA; Geological Engineering, University of Wisconsin-Madison, Madison Wisconsin USA; Weidner, D. J. [Mineral Physics Institute, Stony Brook University, Stony Brook New York USA; Li, L. [Mineral Physics Institute, Stony Brook University, Stony Brook New York USA; Meredith, P. G. [Rock and Ice Physics Laboratory, Department of Earth Sciences, University College London, London UK; Chen, H. [Mineral Physics Institute, Stony Brook University, Stony Brook New York USA; Whitaker, M. L. [Mineral Physics Institute, Stony Brook University, Stony Brook New York USA; Chen, X. [Chemistry Department, Stony Brook University, Stony Brook New York USA

    2017-04-01

    We report new experimental results that quantify the stress distribution within a quartz aggregate during pore collapse and grain crushing. The samples were probed with synchrotron X-ray diffraction as they were compressed in a multianvil deformation apparatus at room temperature from low pressure (tens of megapascal) to pressures of a few gigapascal. In such a material, stress is likely to concentrate at grain-to-grain contacts and vanish where grains are bounded by open porosity. Therefore, internal stress is likely to vary significantly from point to point in such an aggregate, and hence, it is important to understand both the heterogeneity and anisotropy of such variation with respect to the externally applied stress. In our quartz aggregate (grain size of ~4 μm), the measured diffraction peaks broaden asymmetrically at low pressure (tens of megapascal), suggesting that open pores are still a dominant characteristic of grain boundaries. In contrast, a reference sample of novaculite (a highly dense quartz polycrystal, grain size of ~6–9 μm) showed virtually no peak broadening with increasing pressure. In the quartz aggregate, we observed significant deviation in the pressure-volume curves in the range of P = 400–600 MPa. We suggest that this marks the onset of grain crushing (generally denoted as P* in the rock mechanic literature), which is commonly reported to occur in sandstones at pressures of this order, in general agreement with a Hertzian analysis of fracturing at grain contacts.

  6. Provenance search of dune sands using thermoluminescence colour images (TLCIs) from quartz grains

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Tetsuo; Yokosaka, Kyoichi; Habuki, Hisanao; Hayashi, Yasuo (Niigata Univ. (Japan). Faculty of Science)

    1989-01-01

    Thermoluminescence colour images (TLCIs) from quartz grains artificially irradiated with gamma-rays were subjected to a colour image analysing (CIA) system with a mini-computer for data processing. Each unit cell datum, obtained as the red, blue, green (RBG)-values by means of a drum scanner fitted with the TLCI-photograph, was converted into the XYZ-expression usually adopted in a TV-colour system. The total number ratios of blue to red pixels were transformed into a characteristic number (B/R ratio) of respective grain numbers within the mixed TL-colour image of natural sands. After checking the reproducibility of this technique, some dune quartz grains, exposed to 8.8 kGy, were verified to be intimately correlated to a volcanic eruption belonging to the related river-side area. (author).

  7. Single-grain quartz OSL dating of debris flow deposits from Men Tou Gou, south west Beijing, China

    DEFF Research Database (Denmark)

    Zhao, Qiuyue; Thomsen, Kristina Jørkov; Murray, A. S.

    2017-01-01

    of the return frequency of these debris flows, risk assessment and climate change research. In this project, we use quartz single-grain optically stimulated luminescence (OSL) methods to determine the burial ages of five debris flow samples from the Zhai Tang region -60 km west of Beijing. OSL characteristics...... were found to be acceptable despite the low inherent brightness of quartz extracted from these samples. Single-grain thermal transfer was determined to be negligible and beta dose recovery experiments were satisfactory. The quartz single-grain dose distributions strongly indicate that the samples were...

  8. Combining infrared- and green-laser stimulation sources in single-grain luminescence measurements of feldspar and quartz

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.; Murray, A.S.

    2003-01-01

    on grains from two feldspar samples are described. These show that the ratio of the OSL signal under green and IR stimulation is similar for all the feldspar grains. As expected, the ratio for quartz grains is very different, with a much weaker signal when using IR stimulation. For the two feldspars......, the distribution of OSL between the grains and the saturation of the dose response curve shows much less variability than is typically seen for quartz grains. (C) 2003 Elsevier Science Ltd. All rights reserved....

  9. Activity of slip in amphibolite facies, fine-grained recrystallized quartz aggregates: high differential stress during high-T creep of quartz?

    Science.gov (United States)

    Viegas, G.; Menegon, L. M.; Archanjo, C. J.

    2016-12-01

    Quartz axis fabrics are a valuable tool to investigate strain partitioning/distribution in both naturally- and experimentally deformed quartz. Previous works have shown that slip dominates at high temperatures (> 600º C) and water-rich, commonly sub-magmatic conditions, typically associated with large grain sizes and grain boundary migration microstructures. In the Pernambuco shear zone, sheared quartz veins from a protomylonitic granitoid formed during the main amphibolite facies event constrained at mid-crustal conditions (550-600ºC, 5 kbar). The veins contain heterogeneously-deformed primary quartz grains, which typically form both flattened and elongated ribbons as well as more equant porphyroclasts surrounded by aggregates of fine-grained (ca. 20 µm) recrystallized aggregates. Recrystallized quartz with the same fine grain size may also occur in intracrystalline bands within the porphyroclasts. Chessboard extinction is widely observed in the porphyroclasts, and subgrain boundaries are either parallel or normal to the (0001) direction, suggesting slip on both basal and prismatic planes during recrystallization. Crystallographic preferred orientations (CPOs) of porphyroclasts (≥ 100 µm) show maxima of (0001) axes subparallel to Z and X, suggesting coeval glide along both basal and prism planes during shearing. In the recrystallized aggregates, fabric strength tends to become weaker, but still records glide along and directions. These preliminary results suggest that naturally deformed quartz veins record coeval activity of and slip during dynamic recrystallization under amphibolite facies conditions. The microstructure suggests that the CPO of the fine-grained aggregates is host-controlled and results from dominant subgrain rotation recrystallization. To our knowledge, activity of slip in fine-grained recrystallized aggregates has never been reported before. Thus, these preliminary results call into question the general view that slip is expected to be

  10. Transport conditions of mountain-surging glaciers as recorded in the micromorphology of quartz grains (Medvezhiy Glacier, West Pamir

    Directory of Open Access Journals (Sweden)

    Muzińska Agnieszka

    2015-06-01

    Full Text Available In order to reproduce the conditions under which sediments were transported in surging glaciers, samples were taken from the margin and foreland of the surge Medvezhiy Glacier situated in West Pamir (Tajikistan. They were subjected to an analysis of rounding and frosting of quartz sand grains (0.8-1.0 mm and of grain surface micromorphology under scanning electron microscope (SEM. Results obtained showed intense chemical weathering occurred in the majority of quartz grain surfaces, marked in the form of etching and precipitation. Frequencies of microstructures of glacial origin were low; individual microstructures were visible on single grains. A predominance of the crushing process over abrasion in transformation of quartz grains was noted. The commonest microstructures connected with a surge-glacier environment were large and small conchoidal fractures. However, grains with primary features not connected with a glacial environment were equally common. The majority of the grains examined showed features of multiple cycles of mechanical and chemical weathering forming a microtexture under various conditions (overprinting. Common features of grains from surging glaciers are also breakage blocks of >10μm, which depend of the phase of separation of the grain from the rock or on thermal changes in the glacier’s foreland.

  11. Cathodoluminescence characterization of quartz grains from the Upper Cretaceous of dinosaur fossil localities in the Gobi desert, Mongolia

    Science.gov (United States)

    Saneyoshi, M.; Nishido, H.; Masuda, R.; Tsogtbaatar, K.; Chinzorig, T.

    2013-12-01

    The Upper Cretaceous eolian sediments in Mongolia's Gobi desert are one of the most important occurrences of the dinosaurs in the world. Large numbers of confiscated dinosaur fossils illegally worked out by poachers has been stored in the Mongolian Paleontological Center at Ulaanbaatar. In most cases, their localities are unknown. The purpose of this study is to identify their localities by cathodoluminescence (CL) features of quartz grains attached to the dinosaur specimens by comparing to the quartz samples collected from the sediments of circumjacent resources in this area. This study focuses on the confiscated specimen which makes up the nest with the babies' Protoceratops. Most of all Protoceratops in every growth process, have been discovered from the Djadokhta Formation in the Gobi desert. This formation crops out at Tugrikin Shireh and Bayn Dzak in the central part of the Gobi desert, and is derived from medium- to fine-grained sand mainly composed of quartz grains, of which sedimentary environments should be obvious to be eolian. The formation age of the sand beds at Tugrikin Shireh and Bayn Dzak has been estimated to be Middle Campanian. CL spectra of quartz have been demonstrated to show different features between the quartz from hydrothermal, plutonic, volcanic and metamorphic origins, suggesting the spectra reflect the condition of the quartz formation and the local environment. Therefore, we have applied the CL characterization of quartz grains to the evaluation of the provenance of the desert sediments. The quartz grains after sieving (#60-80 mesh size) were embedded in the brass holders with non-luminescent epoxy resin, and their surfaces were polished with 1 μm diamond abrasive. Color CL images obtained by the Luminoscope exhibit blue, violet and red emissions in the grains, suggesting various types of emission centers in the quartz. SEM-CL analysis was conducted using an SEM (JSM-5410) combined with a grating monochromator (Mono CL2) to measure

  12. Reproducibility of optically stimulated luminescence measurements from single grains of Al2O3: C and annealed quartz

    DEFF Research Database (Denmark)

    Truscott, A.J.; Duller, G.A.T.; Bøtter-Jensen, L.

    2000-01-01

    We have measured some aspects concerning the performance of a new instrument for the measurement of optically stimulated luminescence (OSL) from single sand-sized grains. The instrument uses a solid-state laser to stimulate OSL from each grain individually. These grains are placed in a regular grid...... of nine-by-nine holes, which are drilled in the sample disc, We report on tests carried out to determine the precision with which the laser beam can be directed at individual grains in these holes. Single grains of aluminium oxide (Al2O3:C) (90-180 mum) and annealed quartz (90-120 mum) were used to test...

  13. Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete

    Directory of Open Access Journals (Sweden)

    Daria Jóźwiak-Niedźwiedzka

    2016-03-01

    Full Text Available Alkali-silica reaction (ASR is considered as a potential aging-related degradation phenomenon that might impair the durability of concrete in nuclear containments. The objective of this paper is the application of digital analysis of microscopic images to identify the content and size of quartz grains in heavy mineral aggregates. The range of investigation covered magnetite and hematite aggregates, known as good absorbers of gamma radiation. Image acquisition was performed using thin sections observed in transmitted cross-polarized light with λ plate. Image processing, consisting of identification of ferrum oxide and epoxy resin, and the subsequent application of a set of filtering operations resulted in an adequate image reduction allowing the grain size analysis. Quartz grains were classified according to their mean diameter so as to identify the reactive range. Accelerated mortar bar tests were performed to evaluate the ASR potential of the aggregates. The SiO2 content in the heavyweight aggregates determined using the image analysis of thin sections was similar to XRF test result. The content of reactive quartz hematite was 2.7%, suggesting that it would be prone to ASR. The expansion test, according to ASTM C1260, confirmed the prediction obtained using the digital image analysis.

  14. Effects of particle size and laser-induced heating on the Raman spectra of alpha quartz grains.

    Science.gov (United States)

    Chio, Chi Hong; Sharma, Shiv K; Lucey, Paul G; Muenow, David W

    2003-07-01

    Raman spectra of alpha-quartz (Qz) grains of various size (250 microm to Raman and micro-Raman systems. Frequency downshift and line broadening of the 464 cm(-1), v,(Si-O-Si) band are observed in the smallest size group (Raman lines is also used to estimate the vibrational temperature of the samples under different excitation power. The degree of laser-induced heating is more noticeable in the aggregates than in the individual grains with the use of medium-level laser excitation (< or = 150 mW). Heating diminishes with increasing grain size, and it can only be detected in grain aggregates between 11 and 20 microm in diameter using 150 mW excitation. Intensity studies of the v(s)(Si-O-Si) band using individual grains show no noticeable signs of grain size effects. However, grain size effects become an important factor in the study of aggregates in which spectral intensity diminishes with respect to decreasing grain size.

  15. Stress distribution during cold compression of a quartz aggregate using synchrotron X-ray diffraction: Observed yielding, damage, and grain crushing

    Science.gov (United States)

    Cheung, C. S. N.; Weidner, D. J.; Li, L.; Meredith, P. G.; Chen, H.; Whitaker, M. L.; Chen, X.

    2017-04-01

    We report new experimental results that quantify the stress distribution within a quartz aggregate during pore collapse and grain crushing. The samples were probed with synchrotron X-ray diffraction as they were compressed in a multianvil deformation apparatus at room temperature from low pressure (tens of megapascal) to pressures of a few gigapascal. In such a material, stress is likely to concentrate at grain-to-grain contacts and vanish where grains are bounded by open porosity. Therefore, internal stress is likely to vary significantly from point to point in such an aggregate, and hence, it is important to understand both the heterogeneity and anisotropy of such variation with respect to the externally applied stress. In our quartz aggregate (grain size of 4 μm), the measured diffraction peaks broaden asymmetrically at low pressure (tens of megapascal), suggesting that open pores are still a dominant characteristic of grain boundaries. In contrast, a reference sample of novaculite (a highly dense quartz polycrystal, grain size of 6-9 μm) showed virtually no peak broadening with increasing pressure. In the quartz aggregate, we observed significant deviation in the pressure-volume curves in the range of P = 400-600 MPa. We suggest that this marks the onset of grain crushing (generally denoted as P* in the rock mechanic literature), which is commonly reported to occur in sandstones at pressures of this order, in general agreement with a Hertzian analysis of fracturing at grain contacts.

  16. SEM observation of grain boundary structures in quartz-iron oxide rocks deformed at intermediate metamorphic conditions

    Directory of Open Access Journals (Sweden)

    Leonardo Lagoeiro

    2011-09-01

    Full Text Available Several studies have demonstrated the effect of a second phase on the distribution of fluid phase and dissolution of quartz grains. However, as most observations came from aggregates deformed under hydrostatic stress conditions and mica-bearing quartz rocks, 3-D distribution of pores on quartz-quartz (QQB and quartz-hematite boundaries (QHB has been studied. Several fracture surfaces oriented according to finite strain ellipsoid were analyzed. The pore distribution characterizes the porosity and grain shape as highly anisotropic, which results from the nature and orientation of boundaries. QHB have physical/chemical properties very different from QQB, once the hematite plates have strong effect on wetting behavior of fluid, likewise micas in quartzites. They are pore-free flat surfaces, normal to compression direction, suggesting that they were once wetted with a continuous fluid film acting as faster diffusion pathway. At QQB, the pores are faceted, isolated, close to its edges reflecting the crystallographic control and an interconnected network of fluid along grain junctions. The QQB facing the extension direction are sites of fluid concentration. As consequence, the anisotropic dissolution and grain growth were responsible for the formation of hematite plates and tabular quartz grains significantly contributing for the generation of the foliation observed in the studied rocks.Muitos estudos têm demonstrado o efeito de uma segunda fase sobre a distribuição de fase fluida e dissolução de grãos de quartzo. Entretanto, como a maioria das observações vêm de agregados deformados sob condições de tensão hidrostática e em rochas quartzosas ricas em mica, a distribuição 3D de poros e bordas quartzo-quartzo (BQQ e quartzo-hematita (BQH tem sido estudada. Várias superfícies de fraturas orientadas segundo o elipsóide de deformação finita foram analisadas. A distribuição dos poros caracteriza a porosidade e a forma dos grãos como

  17. Frost weathering microstructures on quartz grains as paleoenvironmental indicators in Western Iberia mountain environments (Serra da Estrela, Portugal)

    Science.gov (United States)

    Nieuwendam, Alexandre; Woronko, Barbara; Vieira, Gonçalo

    2016-04-01

    Cailleux analysis (1942) with modifications from Mycielska-Dowgiallo and Woronko (1998) and scanning electron microscope (SEM) following Mahaney (2002) were performed on quartz grains from vertical slope deposits profiles. Other analyses include granulometric composition. The degree of weathering (ST) of single grains was determined by identifying frost-weathering microstructures. The frost action index (FAI) is the average value of the ST for a given sample. The FAI value varies between 0 and 3, and the higher the value, the more intensive the frost weathering (Woronko and Hoch, 2011). The effects of frost weathering comprise several microstructures, such as, breakage blocks and conchoidal fractures and scaling. Chemical weathering effects were also seen, like solution pits, solution crevasses and amorphous precipitation. The values of FAI index of the sediments from the slope deposits vary between 0.6 and 2.05. Samples with a FAI higher than 1.3 indicate that frost weathering occurred for a longer period and was more intense where the dominant microstructures are breakage blocks registered within microdepressions and microfissures. The samples that have a FAI below 1.3, frost weathering was less intense and for a shorter period, with less frequent freeze-thaw cycles and the dominant microstructures are small conchoidal fractures. The values of the FAI in sediments from the slope deposits reveal changes along the vertical profiles. The maximum value of frost-weathering intensity imprinted on quartz grains were observed in sediments near the base of the slope deposits, and this could be attributed to the effects of seasonal freezing and thawing, as well as to the influence of short term temperature changes. The lower frost-weathering intensity was observed in the near-surface layers probably because they were exposed to frost weathering for a shorter time. References Cailleux A. 1942. Les actiones éoliennes périglaciaires en Europe. Mémoires de la Société G

  18. On the importance of grain size in luminescence dating using quartz

    DEFF Research Database (Denmark)

    Timar-Gabor, A.; Buylaert, Jan-Pieter; Guralnik, B.

    2017-01-01

    There are two major problems commonly encountered when applying Optically Stimulated Luminescence (OSL) dating in the high dose range: (i) age discrepancy between different grain sizes, and (ii) age underestimation. A marked and systematic discrepancy between fine-grain (4-11 μm) and coarse...... exponential functions, whose saturation characteristics (D0 values) are clearly anticorrelated with grain diameter (ϕ) through an inverse square root relationship, D0 = A/√ϕ, where A is a scaling factor. While the mechanism behind this grain-size dependency of saturation characteristics still needs...

  19. Testing single-grain quartz OSL methods using sediment samples with independent age control from the Bordes-Fitte rockshelter (Roches d'Abilly site, Central France)

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2016-01-01

    We present quartz single-grain dose distributions for four well-bleached and unmixed sediment samples with independent age control (22–48 ka), from the archaeologically important Bordes-Fitte rockshelter at Roches d'Abilly, France. This site has previously been dated using 14C AMS dating and stan......We present quartz single-grain dose distributions for four well-bleached and unmixed sediment samples with independent age control (22–48 ka), from the archaeologically important Bordes-Fitte rockshelter at Roches d'Abilly, France. This site has previously been dated using 14C AMS dating...

  20. The effect of backscattering on the beta dose absorbed by individual quartz grains

    DEFF Research Database (Denmark)

    Autzen, Martin; Guérin, G.; Murray, A. S.

    2017-01-01

    We describe the effect on dose rates and over-dispersion (OD) of changing the spectrum of energies to which grains of various shapes and volumes are exposed during beta irradiation, either by changing the backscattering medium or attenuating the incident spectrum. Dose rates are found to increase...

  1. Testing single-grain quartz OSL methods using sediment samples with independent age control from the Bordes-Fitte rockshelter (Roches d'Abilly site, Central France)

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2016-01-01

    We present quartz single-grain dose distributions for four well-bleached and unmixed sediment samples with independent age control (22–48 ka), from the archaeologically important Bordes-Fitte rockshelter at Roches d'Abilly, France. This site has previously been dated using 14C AMS dating and stan...

  2. OSL dating as a possible tool for provenance study of fine grained quartz/polymineral from Lake Suigetsu sediments

    Science.gov (United States)

    Sugisaki, S.; Murray, A. S.; Buylaert, J.; Tada, R.; Suzuki, Y.; Nagashima, K.; Schwenninger, J.; Haraguchi, T.; Gotanda, K.; Nakagawa, T.

    2013-12-01

    m fraction was extracted from the sediments, and equivalent doses were measured using a double SAR (infrared (IR) and blue light) and post-IR IR (pIRIR 180) respectively. The results show that quartz and polyminerals from type 1 lithology give relatively low and similar equivalent doses throughout each section, whilst quartz and polyminerals in layers of type 2 and 3 give up to 6 times higher equivalent dose than those of adjacent type 1 sediments. We discuss the possible source of quartz in each type of lithology based on fine-grained quartz and polymineral OSL and identify the most suitable lithology for OSL dating for future study.

  3. Mean-life evaluation of naturally trapped electrons associated with red- and blue-thermoluminescencent quartz-grains from dune sand

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, Tetsuo; Fujita, Hiroki; Yasuda, Kenya [Niigata Univ. (Japan). Faculty of Science

    1999-11-01

    The trapping energy level (E) from conduction band is well known to be intimately correlated with the mean lives ({tau}) of captured electrons and holes in quartz grains, resulting in the applicable criterion of thermoluminescence (TL) dating using a coarse grain method. The experimental evaluation of accurate E-values has been carried out using an initial rise method combined with radioluminescence (RL) measurements for the correction of thermal quenching effects at higher temperature. The naturally accumulated red-TL (RTL) and blue-TL (BTL) grains from quartz grains from a dune sand were subjected to the present method. As a result, the correction of the thermal quenching effects always brought the higher E-values in the range of 0.1 to 0.25 eV in comparison with the low activation energies from initial rise method of glowcurve analysis alone. It was again confirmed that the E-value of RTL gives higher than that of BTL in natural quartz grains. Consequently, the finally evaluated mean lives of RTL were certainly longer than those of BTL. This result supports that the RTL-dating is more preferable for the age-determination beyond 500 ka because of high stability of RTL. The E-values were also compared with the results from the isothermal analysis of TL-glowcurves. (author)

  4. Reconstruction of sediment provenance and transport processes from the surface textures of quartz grains from Late Pleistocene sandurs and an ice-marginal valley in NW Poland

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2015-06-01

    Full Text Available During the Pomeranian phase of the Weichselian glaciation (~17-16 ka, the Toruń-Eberswalde ice-marginal valley (NW Poland and easternmost Germany drained water from the Pomeranian ice sheet, while intensive aeolian processes took place across Europe in the foreland of the Scandinavian ice sheet (‘European Sand Belt’. The micromorphology of the quartz grains in the Toruń-Eberswalde ice-marginal valley shows no traces of these aeolian processes, or only vague signs of aeolian abrasion. This is unique among the aeolian sediments in other Pleistocene ice-marginal valleys in this part of Europe. The study of the surfaces of the quartz grains shows that the supply of grains by streams from the south was minimal, which must be ascribed to the climate deterioration during the Last Glacial Maximum, which resulted in a decrease of the discharge of these extraglacial rivers to the ice-marginal valley.

  5. Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

    OpenAIRE

    Woronko, Barbara; Zieliński, Paweł; Sokołowski, Robert Jan

    2015-01-01

    We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maxi-mum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian ...

  6. Raman Imaging Spectroscopy of a Putative Microfossil from the ∼3.46 Ga Apex Chert: Insights from Quartz Grain Orientation.

    Science.gov (United States)

    Bower, D M; Steele, A; Fries, M D; Green, O R; Lindsay, J F

    2016-02-01

    The utility of nondestructive laser Raman for testing the biogenicity of microfossil-like structures in ancient rocks is promising, yet results from deposits like the ∼3.46 Ga Apex chert remain contentious. The essence of the debate is that associated microstructures, which are not purported to be microfossils, also contain reduced carbon that displays Raman D- and G-band peaks similar to those seen in the purported microfossils. This has led to the hypothesis that all features including reported microfossils are due to compression of nonfossil carbon during crystal growth around quartz spherulites or more angular crystals. In this scenario, the precursor to this macromolecular carbon may or may not have been of biogenic origin, while the arcuate and linear features described would be pseudofossils. To test this hypothesis, we have undertaken 2-D micro-Raman imaging of the Eoleptonema apex holotype and associated features using instrumentation with a high spatial and spectral resolution. In addition to this, we utilized the ratio of two Raman active quartz mode intensities (I129/I461) to assess quartz grain orientation and grain-splitting artifacts. These data lead us to conclude that the holotype of Eoleptonema apex is a sheet-shaped pseudofossil that appears to be a carbon infilled intragranular crack; therefore other holotypes should be carefully reexamined for syngenicity.

  7. Transport and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impacts of input concentration, grain size and flow rate.

    Science.gov (United States)

    Hou, Jun; Zhang, Mingzhi; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Xu, Yi; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Liu, Zhilin

    2017-12-15

    This study investigated the transport and long-term release of stabilized poly vinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) in a quartz sand column with various sand grain sizes (0.3-0.5 μm, 0.5-1.0 μm, 1.0-2.0 μm), input concentrations of PVP-AgNP solution (1, 5, 15, 25 mg/L), and flow rates corresponding to a filter velocities (1.0, 1.5, 2.0, 2.5 mL/min-0.14, 0.21, 0.28, 0.35 cm/min) by determining breakthrough curves, retention profiles, and long-term release curves. Breakthrough curves and retention profiles were simulated by a mathematical model based on the advection dispersion equation coupled with second-order kinetics. The increased transport of PVP-AgNPs in quartz sand occurred with increased grain sizes and reduced input concentrations, and the transport can be predicted by the colloid filtration theory and DLVO theory. The long-term (one week) release amounts of retained PVP-AgNPs were 42.78%, 31.45%, and 10.95% in the fine, medium, and coarse sand columns, respectively, and were 34.70%, 40.79%, 47.24%, and 57.32% at flow rates of 0.0363, 0.0436, 0.0545, and 0.0726 mL/min, respectively. The released quantity of retained PVP-AgNPs decreased as the sand grain size increased. This phenomenon is opposite with the trend of increased transport of PVP-AgNPs with increased grain size in the transport test, which most likely because colloidal filtration regulates the transport process and adsorption (and desorption) dominates the release process. Increasing the flow rate increased the shear force on the particles, which improved the release of PVP-AgNPs. The results of the release tests further verified our previous published studies showing that the long-term release of retained PVP-AgNPs in the quartz sand was mostly in the form of released nanoparticles rather than ions. The results of this study indicated that sand grain size, input concentration, and flow rate have a prominent influence on the transport and long-term release behavior of

  8. Reconstruction of sediment provenance and transport processes from the surface textures of quartz grains from Late Pleistocene sandurs and an ice-marginal valley in NW Poland

    OpenAIRE

    Woronko Barbara; Pisarska-Jamroży Małgorzata; Loon A.J. (Tom) van

    2015-01-01

    During the Pomeranian phase of the Weichselian glaciation (~17–16 ka), the Toruń-Eberswalde ice-marginal valley (NW Poland and easternmost Germany) drained water from the Pomeranian ice sheet, while intensive aeolian process -es took place across Europe in the foreland of the Scandinavian ice sheet (‘European Sand Belt’). The micromorphology of the quartz grains in the Toruń-Eberswalde ice-marginal valley shows no traces of these aeolian processes, or only vague signs of aeolian a...

  9. Thermal transfer and apparent-dose distributions in poorly bleached mortar samples: Results from single grains and small aliquots of quartz

    DEFF Research Database (Denmark)

    Jain, M.; Thomsen, Kristina Jørkov; Bøtter-Jensen, L.

    2004-01-01

    ;, this process releases all the prior trapped charge and simultaneously sensitises the quartz. Unfortunately unheated materials such as mortar and concrete are more common in industrial sites and particularly in nuclear installations. These materials are usually exposed to daylight during quarrying...... dosimetry. The challenge in using such materials as retrospective dosemeters, is in identifying these well-bleached grains when an accident dose has been superimposed on the original dose distribution. We investigate here, using OSL, the background dose in three different mortar samples: render, whitewash...

  10. Modelling dose rate to single grains of quartz in well-sorted sand samples: The dispersion arising from the presence of potassium feldspars and implications for single grain OSL dating

    DEFF Research Database (Denmark)

    Guerin, Guillaume; Jain, Mayank; Thomsen, Kristina Jørkov

    2015-01-01

    statistical tools to characterize De populations and (ii) modelling, with a specifically designed GEANT4 code, dose rate distributions arising from the presence of potassium feldspar grains in well-sorted sands. The model uses Monte Carlo simulations of beta emissions and interactions in a random close......Single grain OSL has become a widely used approach in Quaternary geochronology. However, the origins of De distributions and the sources of variation in individual dose estimates are still poorly understood. The amount of scatter in these distributions on top of the known uncertainties...... in measurement and analysis is defined by overdispersion and this quantity is generally used for weighting individual De values to calculate a central equivalent dose. In this study, we address the nature and amount of different sources of dispersion in quartz single grain De estimates, by (i) using appropriate...

  11. Climate evolution during the Pleniglacial and Late Glacial as recorded in quartz grain morphoscopy of fluvial to aeolian successions of the European Sand Belt

    Directory of Open Access Journals (Sweden)

    Woronko Barbara

    2015-06-01

    Full Text Available We present results of research into fluvial to aeolian successions at four sites in the foreland of the Last Glacial Maximum, i.e., the central part of the “European Sand Belt”. These sites include dune fields on higher-lying river terraces and alluvial fans. Sediments were subjected to detailed lithofacies analyses and sampling for morphoscopic assessment of quartz grains. Based on these results, three units were identified in the sedimentary succession: fluvial, fluvio-aeolian and aeolian. Material with traces of aeolian origin predominate in these sediments and this enabled conclusions on the activity of aeolian processes during the Pleniglacial and Late Glacial, and the source of sediment supply to be drawn. Aeolian processes played a major role in the deposition of the lower portions of the fluvial and fluvio-aeolian units. Aeolian material in the fluvial unit stems from aeolian accumulation of fluvial sediments within the valley as well as particles transported by wind from beyond the valley. The fluvio-aeolian unit is composed mainly of fluvial sediments that were subject to multiple redeposition, and long-term, intensive processing in an aeolian environment. In spite of the asynchronous onset of deposition of the fluvio-aeolian unit, it is characterised by the greatest homogeneity of structural and textural characteristics. Although the aeolian unit was laid down simultaneously, it is typified by the widest range of variation in quartz morphoscopic traits. It reflects local factors, mainly the origin of the source material, rather than climate. The duration of dune-formation processes was too short to be reflected in the morphoscopy of quartz grains.

  12. Characterization of magnetite particles in shocked quartz by means of electron- and magnetic force microscopy: Vredefort, South Africa

    CSIR Research Space (South Africa)

    Cloete, M

    1999-11-01

    Full Text Available ) in quartz generally accepted as typical shock lamellae. The magnetite particles along shock lamellae in quartz grains virtually all show uniform crystallographic orientations. In most instances, the groups of magnetite within different quartz grains...

  13. Geology and geochemistry of giant quartz veins from the ...

    Indian Academy of Sciences (India)

    The green colour is sometimes due to the presence of secondary epi- dote and chlorite. Very fine-grained green quartz similar to colloidal quartz is also observed in places. Quartz grains occurring within grey-coloured giant veins are highly strained in nature. A number of thin (up to 10cm; figure 3c) sub- vertical, milky white ...

  14. Neurolinguistic analysis of the language abilities of a patient with a "double disconnection syndrome": a case of subangular alexia in the presence of mixed transcortical aphasia.

    Science.gov (United States)

    Pirozzolo, F J; Kerr, K L; Obrzut, J E; Morley, G K; Haxby, J V; Lundgren, S

    1981-01-01

    In contrast to the classic form of alexia without agraphia, subangular alexia results from a single lesion located deep in the white matter of the left parietal lobe. In the present report, a patient with subangular alexia and features of mixed transcortical aphasia is described. Neurolinguistic findings include: alexia without agraphia, paucity of spontaneous speech, moderate auditory comprehension difficulty, excellent repetition, echopraxia, colour agnosia, and naming disorder. Neurolinguistic tests revealed intact phonological organisation and grammatical filter." Our studies revealed a "double disconnection syndrome," the co-existence of two relatively rare neurobehavioural disorders. Furthermore, the studies reported here clearly show dissociations of language functions in both the visual and auditory modality, which demonstrates that the stages of language processing are separable. Images PMID:7217972

  15. Neurolinguistic analysis of the language abilities of a patient with a "double disconnection syndrome": a case of subangular alexia in the presence of mixed transcortical aphasia.

    Science.gov (United States)

    Pirozzolo, F J; Kerr, K L; Obrzut, J E; Morley, G K; Haxby, J V; Lundgren, S

    1981-02-01

    In contrast to the classic form of alexia without agraphia, subangular alexia results from a single lesion located deep in the white matter of the left parietal lobe. In the present report, a patient with subangular alexia and features of mixed transcortical aphasia is described. Neurolinguistic findings include: alexia without agraphia, paucity of spontaneous speech, moderate auditory comprehension difficulty, excellent repetition, echopraxia, colour agnosia, and naming disorder. Neurolinguistic tests revealed intact phonological organisation and grammatical filter." Our studies revealed a "double disconnection syndrome," the co-existence of two relatively rare neurobehavioural disorders. Furthermore, the studies reported here clearly show dissociations of language functions in both the visual and auditory modality, which demonstrates that the stages of language processing are separable.

  16. Extensive authigenic quartz overgrowths in the gas-bearing Haynesville-Bossier Shale, USA

    Science.gov (United States)

    Dowey, Patrick J.; Taylor, Kevin G.

    2017-07-01

    In sandstone reservoirs, despite grain rearrangement during compaction, significant pore volumes may be retained prior to the onset of late diagenetic quartz cementation. In mudstone reservoirs, grain rearrangement during compaction results in significant pore volume reduction prior to late diagenesis. Where quartz overgrowths have been previously reported in post-compaction mudstones they have been in volumetrically low concentrations and interpreted as anomalous occurrences. Quartz cementation alters rock brittleness resulting in changes to mechanical fracture properties. Quartz overgrowths reduce reservoir porosity and permeability. We present petrographic evidence of two phases of quartz cement in the Haynesville-Bossier Shale: (i) grain replacive and (ii) quartz overgrowths. Carbonate grain replacement is volumetrically low (< 1%). Quartz overgrowths identified from SEM-CL imaging are volumetrically more significant (8-13%). Quartz overgrowths were most commonly observed in the sandy and coarse mudstone microfacies, but are present in both medium and fine mudstone microfacies. Petrographic evidence indicates three processes in the development of quartz overgrowths. Mica and pyrite are (i) engulfed and (ii) displaced by quartz overgrowth cement. The absence of a supportive, primary granular framework surrounding engulfed detrital and early authigenic minerals would indicate that quartz overgrowths are also (iii) replacive. Pressure dissolution of detrital quartz silt grains and smectite-to-illite transformation are likely sources of silica for quartz cement. This study is the first to document large-scale, replacive, authigenic quartz overgrowth development within a producing mudstone.

  17. Fe-oxide grain coatings support bacterial Fe-reducing metabolisms in 1.7-2.0 km-deep subsurface quartz arenite sandstone reservoirs of the Illinois Basin (USA

    Directory of Open Access Journals (Sweden)

    Yiran eDong

    2014-09-01

    Full Text Available The Cambrian-age Mt. Simon Sandstone, deeply buried within the Illinois Basin of the midcontinent of North America, contains quartz sand grains ubiquitously encrusted with iron-oxide cements and dissolved ferrous iron in pore-water. Although microbial iron reduction has previously been documented in the deep terrestrial subsurface, the potential for diagenetic mineral cementation to drive microbial activity has not been well studied. In this study, two subsurface formation water samples were collected at 1.72 and 2.02 km, respectively, from the Mt. Simon Sandstone in Decatur, Illinois. Low-diversity microbial communities were detected from both horizons and were dominated by Halanaerobiales of Phylum Firmicutes. Iron-reducing enrichment cultures fed with ferric citrate were successfully established using the formation water. Phylogenetic classification identified the enriched species to be related to Vulcanibacillus from the 1.72 km depth sample, while Orenia dominated the communities at 2.02 km of burial depth. Species-specific quantitative analyses of the enriched organisms in the microbial communities suggest that they are indigenous to the Mt. Simon Sandstone. Optimal iron reduction by the 1.72 km enrichment culture occurred at a temperature of 40oC (range 20 to 60oC and a salinity of 25 parts per thousand (range 25-75 ppt. This culture also mediated fermentation and nitrate reduction. In contrast, the 2.02 km enrichment culture exclusively utilized hydrogen and pyruvate as the electron donors for iron reduction, tolerated a wider range of salinities (25-200 ppt, and exhibited only minimal nitrate- and sulfate-reduction. In addition, the 2.02 km depth community actively reduces the more crystalline ferric iron minerals goethite and hematite. The results suggest evolutionary adaptation of the autochthonous microbial communities to the Mt. Simon Sandstone and carries potentially important implications for future utilization of this reservoir

  18. [Study on the accuracy of pressure determined by raman spectra of quartz].

    Science.gov (United States)

    Guo, Ning; Zheng, Hai-fei

    2010-08-01

    Quartz as a pressure gauge and its accuracy were studied by Raman spectroscopy at 25 degrees C and ambient pressure. The result shows that even at same temperature and pressure, the Si-O vibrational mode for different grains of quartz varies between 463.59 and 464.65 cm(-1), with (+/- 0.1- +/- 0.3) cm(-1) error. The maximum difference of various grains of quartz is up to 1.06 cm(-1), much higher than the measurement error. The authors believe that the variety is resulted from the stress in the internal grains of quartz, which formed during crushing quartz into small grain. Therefore, Raman spectrum for quartz has to be firstly measured as a reference of zero pressure at ambient pressure and temperature in the experimental study by using diamond anvil cell. In addition, wavenumber drift of the spectrometer and the unstable temperature will also cause remarkable error for measuring pressure.

  19. QUARTZ FIBER ELECTROSCOPES

    Science.gov (United States)

    Henderson, R.P.

    1957-09-17

    An instrument carried unobtrusively about the person such as in a finger ring to indicate when that person has been exposed to an unusual radiation hazard is described. A metallized quartz fiber is electrically charged to indicate a full scale reading on an etched glass background. The quartz fiber and the scale may be viewed through a magnifying lens for ease of reading. Incident radiation will ionize gaseous particles in the sealed structure thereby allowing the charge to leak off the quartz fiber with its resulting movement across the scale proportionally indicating the radiation exposure.

  20. Vacuum electrolysis of quartz

    Science.gov (United States)

    King, James Claude

    1976-01-13

    The disclosure is directed to a method for processing quartz used in fabricating crystal resonators such that transient frequency change of resonators exposed to pulse irradiation is virtually eliminated. The method involves heating the crystal quartz in a hydrogen-free atmosphere while simultaneously applying an electric field in the Z-axis direction of the crystal. The electric field is maintained during the cool-down phase of the process.

  1. Radiation Damage of Quartz Fibers

    OpenAIRE

    Hagopian, V

    1999-01-01

    Quartz fibers are used in high energy physics experiments as the active medium in high radiation area calorimetry. Quartz fibers are also used in the transmission of optical signals. Even though quartz does not damage by moderate amounts of irradiation, the clad of the fibers and the protective coating ( buffer) do damage reducing light transmission. Various types of quartz fibers have been irradiated and measured for light transmission. The most radiation hard quartz fibers are those with qu...

  2. Deposits of gold-quartz formation in the Priamur province

    Directory of Open Access Journals (Sweden)

    В. А. Степанов

    2017-03-01

    Small deposits of near-bottom ore pipe are quite rare. Ore bodies are represented by quartz veins and zones of metasomatites. Gold is mostly free, of fine and super fine grain size. The prevailing trace element is mercury. Attribution of gold-quartz deposits to a certain part of ore pipe can facilitate more precise estimation of their prospects. In its own turn, this will allow to choose more favorable objects for further evaluation.

  3. Microscopy and Cathodoluminescence Spectroscopy Characterization of Quartz Exhibiting Different Alkali-Silica Reaction Potential.

    Science.gov (United States)

    Kuchařová, Aneta; Götze, Jens; Šachlová, Šárka; Pertold, Zdeněk; Přikryl, Richard

    2016-02-01

    Different quartz types from several localities in the Czech Republic and Sweden were examined by polarizing microscopy combined with cathodoluminescence (CL) microscopy, spectroscopy, and petrographic image analysis, and tested by use of an accelerated mortar bar test (following ASTM C1260). The highest alkali-silica reaction potential was indicated by very fine-grained chert, containing significant amounts of fine-grained to cryptocrystalline matrix. The chert exhibited a dark red CL emission band at ~640 nm with a low intensity. Fine-grained orthoquartzites, as well as fine-grained metamorphic vein quartz, separated from phyllite exhibited medium expansion values. The orthoquartzites showed various CL of quartz grains, from blue through violet, red, and brown. Two CL spectral bands at ~450 and ~630 nm, with various intensities, were detected. The quartz from phyllite displayed an inhomogeneous dark red CL with two CL spectral bands of low intensities at ~460 and ~640 nm. The massive coarse-grained pegmatite quartz from pegmatite was assessed to be nonreactive and displayed a typical short-lived blue CL (~480 nm). The higher reactivity of the fine-grained hydrothermal quartz may be connected with high concentrations of defect centers, and probably with amorphized micro-regions in the quartz, respectively; indicated by a yellow CL emission (~570 nm).

  4. The role of deformation on trace element solubility in quartz: Observations from naturally deformed quartz-rich rocks and experimentally deformed Ti-doped synthetic quartz aggregates

    Science.gov (United States)

    Nachlas, W.; Whitney, D. L.; Teyssier, C.; Seaton, N. C.; Hirth, G.

    2011-12-01

    Recent advances in resolving the significance of trace element solubility (e.g., Ti) in quartz have largely focused on reconstructing the P-T-X conditions of equilibration. The calibration of Ti in quartz thermometry (TitaniQ) and the refined precision of analytical instrumentation for in-situ quantitative analysis make this a very effective technique for thermobarometric reconstructions of geologic events. However, the incorporation of trace impurities in the quartz lattice is likely to be affected by deformation, as crystal plasticity may influence the mobility of trace elements. To investigate the role of dynamic recrystallization on the accommodation of changing trace element solubility in quartz, this study combines measurements of trace element concentrations and distribution in naturally deformed quartz with high P-T deformation experiments of trace element doped synthetic quartz aggregates. Measurements of the trace element concentration of quartz from an extensional shear zone in the North American Cordillera provide insight to the behavior of trace elements during dynamic recrystallization associated with retrograde cooling and exhumation. Rutile-bearing quartzite mylonites from the Thor-Odin core complex, British Columbia, were selected for analysis based on the ability to determine Ti activity, the identification of a suitable protolith, and the existence of stable isotope thermometry that allows comparison with independent thermometers. High resolution quantitative analysis reveals systematic compositional variability: the interior of deformed quartz grains preserves a higher Ti concentration than the adjacent rim of the grain. This correlation between microstructural domain and trace element distribution suggests a relationship between the solubility of trace impurities and the mechanism of dynamic recrystallization in quartz. To experimentally investigate the role of deformation on the solubility of trace elements in quartz, synthetic quartz

  5. Quartz crystal growth

    Science.gov (United States)

    Baughman, Richard J.

    1992-01-01

    A process for growing single crystals from an amorphous substance that can undergo phase transformation to the crystalline state in an appropriate solvent. The process is carried out in an autoclave having a lower dissolution zone and an upper crystallization zone between which a temperature differential (.DELTA.T) is maintained at all times. The apparatus loaded with the substance, solvent, and seed crystals is heated slowly maintaining a very low .DELTA.T between the warmer lower zone and cooler upper zone until the amorphous substance is transformed to the crystalline state in the lower zone. The heating rate is then increased to maintain a large .DELTA.T sufficient to increase material transport between the zones and rapid crystallization. .alpha.-Quartz single crystal can thus be made from fused quartz in caustic solvent by heating to 350.degree. C. stepwise with a .DELTA.T of 0.25.degree.-3.degree. C., increasing the .DELTA.T to about 50.degree. C. after the fused quartz has crystallized, and maintaining these conditions until crystal growth in the upper zone is completed.

  6. The effect of quartz on the flotation of pyrite depressed by serpentine

    Directory of Open Access Journals (Sweden)

    Bo Feng

    2015-01-01

    Full Text Available The effect of quartz particles on the flotation of pyrite depressed by serpentine has been investigated through flotation tests, adsorption tests, zeta potential measurements and DLVO calculation. The results show that the presence of hydrophilic serpentine slimes on pyrite surface reduces collector adsorption and results in lower recovery of pyrite. The finer the serpentine slime is, the lower the pyrite recovery will be. Quartz particles do not interfere with pyrite flotation. However, the addition of quartz particles increases the adsorption of collector on pyrite surface and limits the detrimental effect of serpentine on pyrite flotation. The fine-grained quartz is more effective. Zeta potential measurements and DLVO calculation illustrate that the zeta potential of quartz is more negative than that of pyrite and the attraction force between serpentine and quartz is stronger than force between serpentine and pyrite, thus some serpentine slimes were transferred from pyrite surface to quartz in the process of attrition.

  7. Structural analysis of the fracture surface of a heterogeneous body (quartz sandstone)

    Science.gov (United States)

    Vettegren', V. I.; Mamalimov, R. I.; Kulik, V. B.; Patonin, A. V.; Ponomarev, A. V.; Sobolev, G. A.; Shcherbakov, I. P.

    2017-07-01

    The structure of surface layers of quartz sandstone with a thickness of 1 μm before and after destruction by a compressive stress is studied by methods of infrared, photoluminescent, and Raman spectroscopy. Before destruction, this layer contained quartz grains cemented with montmorrillonite and kaolinite. The grains are covered with a thin water layer and have crystallographic defects: Si-O-, self-trapped excitons, AlOH and LiOH compounds, [AlO4]- centers, etc. The destructed surface contains separate quartz grains with sizes of 2 μm and a reduced defect concentration. It is assumed that the defects reduce the strength of quartz grains, which are destroyed in the first turn.

  8. Investigations on Local Quartz Sand for Application in Glass Industry

    Science.gov (United States)

    Dararutana, Pisutti; Chetanachan, Prukswan; Wathanakul, Pornsawat; Sirikulrat, Narin

    2009-03-01

    Silica or glass sand is a special type of quartz sand that is suitable for glass-making, because of its high silica content, and its low content of iron oxide and other compounds. In Thailand, deposits of quartz sand are found as the beach and the river sands in many areas; eastern, southern, northeastern and northern. In this work, grain-size distribution and chemical analyses were carried out on 10 sand samples taken from various localities in Thailand such as Chanthaburi, Trat, Rayong, Chumphon, Nakhon Si, Pattani, Phuket, Songkhla, Nong Khai, and Tak provinces. The geological resources show that most of them are the surface-to-near-surface glass sand deposits. The sand grains in most deposits were mainly angular-to-rounded, except in some areas of either angular or rounded grains. Chemical analysis showed that the sands contained more than 95wt% silica and low content of Fe, Al, Ca, Mg, Na, and K. The concentration levels of these components in the samples confirm with internationally acceptable standard for glass production. The quartz sand dressing plants that used the spiral classifier to improve the properties of the quartz sands to meet the standard specifications are mostly located in the eastern area. It can be concluded that most of the quartz sand deposits in Thailand investigated show well-sorted grain-size with considerable purity, i.e. high-grade quality. The advanced works resulted in that these raw quartz sands can be used as raw material for fabrication of soda-lime, lead crystal, and lead-free high refractive index glasses. The colorless and various colored glass products have been satisfactorily used in the domestic art and glass manufactures.

  9. Synthesis and deformation of a Ti doped quartz aggregate

    Science.gov (United States)

    Nachlas, William O.; Hirth, Greg; Teyssier, Christian; Whitney, Donna L.; Zimmerman, Mark

    2013-04-01

    generate the equilibrium concentration predicted by previous solubility calibrations for selected P-T conditions. Experiments were performed using a shear assembly to deform quartz samples to high shear strain in dislocation creep at constant temperature, pressure, and strain rate for 24, 48, and 72 h with and without the addition of 0.1 wt% H2O. Experiments were also run under hydrostatic conditions for equivalent lengths of time for comparison with deformed samples. Experimental specimens were prepared as a two layer sample with a doped half and an undoped half to study Ti mobility during deformation. Experimental samples are analyzed with EMPA and SIMS to determine the Ti concentration of quartz in the sample, SEM-CL to observe the distribution of Ti in quartz grains, and SEM-EBSD to evaluate crystallographic fabrics and grain size. Results suggest that the duration of dynamic recrystallization influences the final Ti concentration, implying the importance of kinetics and diffusion even at the elevated temperatures of the experiments. Water content affects Ti concentration, potentially owing to the importance of point defect concentration on the solubility of Ti in quartz. Furthermore, recrystallized grain size shows a dependence on Ti concentration, as samples doped at supersaturated levels recrystallize with finer grain sizes relative to undoped samples. This suggests that exceeding the equilibrium solubility of Ti in quartz may pin grain boundary migration. The ultimate expression of Ti supersaturation in quartz is strain-induced rutilation and the progressive rotation and boudinage of exsolved rutile needles.

  10. Quartz resonator processing system

    Science.gov (United States)

    Peters, Roswell D. M.

    1983-01-01

    Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

  11. Albite [yields] jadeite + quartz transformation in rock: Mechanism and kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, S.R.; Kirby, S.H. (Geological Survey, Menlo Park, CA (United States)); Hacker, B.R.

    1992-01-01

    Recent work on the calcite [yields] aragonite transformation using fully dense marble revealed significant differences from earlier experiments on powders and single-crystals. The reaction rate is retarded by a factor of > 1,000 and reaction mechanisms and resultant textures are considerably more complex. Stimulated by this, the authors conducted a study of the albite [yields] jadeite + quartz/coesite transformation in a fully dense albitite. Again the results are in marked contrast with previous powder-based studies of this archetypal metamorphic reaction. Solid cores of albitite were held at temperatures of 500-1,200 C and at pressure oversteps of 500 MPa into the jadeite + quartz stability field for 1--8 days in piston-cylinder apparatus. Samples that were dried in vacuum transformed appreciably only at temperatures in excess of 1,000 C. At all grain boundaries there is subequal transformation to micron-scale intergrowths of jadeite + quartz. Samples that were vacuum-impregnated with 1 wt% water contain jadeite + quartz to temperatures as low as 600 C. In contrast to the dried samples, transformation is much less homogeneous. The jadeite + quartz intergrowths do not form rows of subparallel crystals on grain boundaries, but rather are flower-shaped clusters that radiate outward from single nucleation sites at 3-grain edges and 4-grain corners. Compared to powders, pressure oversteps a factor of 10 greater are necessary to induce equivalent reaction in albitite. The sluggishness of this reaction has important implications for the evolution of the lower continental crust and subducting oceanic crust in terms of their (1) seismic velocity profiles, (2) petrological evolution, and (3) buoyancy forces, stresses and vertical crustal movements connected with densification and dilatational reactions.

  12. Synchrotron FTIR imaging of OH in quartz mylonites

    Science.gov (United States)

    Kronenberg, Andreas K.; Hasnan, Hasnor F. B.; Holyoke, Caleb W., III; Law, Richard D.; Liu, Zhenxian; Thomas, Jay B.

    2017-10-01

    Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4-8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples detectable water in highly sheared MCT mylonites challenge our understanding of quartz rheology. However, where water absorption bands can be detected and compared with deformation microstructures, OH concentration maps provide information on the histories of deformation and recovery, evidence for the introduction and loss of fluid inclusions, and water weakening processes.

  13. Quartz luminescence response to a mixed alpha-beta field: Investigations on Romanian loess

    DEFF Research Database (Denmark)

    Constantin, Daniela; Jain, Mayank; Murray, Andrew S.

    2015-01-01

    Previous SAR-OSL dating studies using quartz extracted from Romanian and Serbian loess samples report SAR-OSL dose-response curves on fine grained (4-11μm) quartz that grow to much higher doses compared to those of coarse-grained (63-90, 90-125, 125-180μm) quartz. Furthermore, quartz SAR......-OSL laboratory dose response curves do not reflect the growth of the OSL signal in nature. A main difference in coarse- and fine-grained quartz dating lies in the alpha irradiation history, but the effect of mixed alpha-beta fields has so far received little attention. In the present study we investigate whether...... the alpha dose experienced by fine grains over geological cycles of irradiation and bleaching may have an effect on the saturation characteristics of the laboratory dose response. By applying time resolved optically stimulated luminescence we confirm that the OSL signals induced in quartz by alpha and beta...

  14. Complex fragmentation and silicification structures in fault zones: quartz mineralization and repeated fragmentation along the Fountain Range Fault (Mt. Isa Inlier, Australia)

    Science.gov (United States)

    Seybold, Lina; Blenkinsop, Tom; Heuss, Soraya; Ord, Alison; Kruhl, Jörn H.

    2015-04-01

    In large-scale fault zones fracture networks are commonly generated by high volumes of pressurized fluids, followed by quartz precipitation. In this way large amounts of quartz are formed as microcrystalline masses and as complex vein systems, with partly highly different textures, as a result of different formation processes. Based on field and microstructural data and the quantification of vein patterns, the spatial and temporal connection between fragmentation, quartz crystallization and fluid and material flow along the Fountain Range Fault at Fountain Springs was investigated. Dextral strike-slip led to up to 25 km horizontal displacement along the fault. Due to various fragmentation and quartz formation processes, a ca. 100 m high, 80 - 100 m wide and km-long quartz ridge with numerous vein systems and variable microfabrics was formed. Locally, lenses of highly altered metamorphic wall-rocks occur in the quartz zone. Where exposed, the contact to wall rocks is sharp. Millimetre- to decimetre-thick quartz veins penetrate the wall-rocks only within metre distance from the contact. Several clearly distinguishable fine-grained reddish, brownish to dark and pigment-rich quartz masses form up to 50 m wide and up to several 100 m long steep lenses that build the major part of the silicified fault zone. A chronology can be established. Some of these lenses are oriented slightly oblique to the general trend of the quartz zone, in agreement with the supposed dextral strike slip along the fault. Numerous generations of typically µm-cm thick quartz veins transect the microcrystalline quartz masses and, locally, form anisotropic networks. In the quartz masses, angular fragments often composed of quartz with, again, internal fragmentation structures, indicate earlier fracturing and silicification events. Within the veins, quartz forms geodes, locally filled with fine-grained reddish quartz and palisade structures with feathery textures and fluid-inclusion zoning

  15. Synchrotron FTIR imaging of OH in quartz mylonites

    Directory of Open Access Journals (Sweden)

    A. K. Kronenberg

    2017-10-01

    Full Text Available Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.Synchrotron infrared (IR radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR plates can be prepared with thicknesses down to 4–8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x − y stage, spectra have been collected over specimen areas of nearly 4.5 mm2. This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland and Main Central Thrust (Himalayas.Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT exhibit a large and variable 3400 cm−1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and paragneisses deformed

  16. Synchrotron FTIR imaging of OH in quartz mylonites

    Energy Technology Data Exchange (ETDEWEB)

    Kronenberg, Andreas K.; Hasnan, Hasnor F. B.; Holyoke III, Caleb W.; Law, Richard D.; Liu, Zhenxian; Thomas, Jay B.

    2017-01-01

    Previous measurements of water in deformed quartzites using conventional Fourier transform infrared spectroscopy (FTIR) instruments have shown that water contents of larger grains vary from one grain to another. However, the non-equilibrium variations in water content between neighboring grains and within quartz grains cannot be interrogated further without greater measurement resolution, nor can water contents be measured in finely recrystallized grains without including absorption bands due to fluid inclusions, films, and secondary minerals at grain boundaries.

    Synchrotron infrared (IR) radiation coupled to a FTIR spectrometer has allowed us to distinguish and measure OH bands due to fluid inclusions, hydrogen point defects, and secondary hydrous mineral inclusions through an aperture of 10 µm for specimens > 40 µm thick. Doubly polished infrared (IR) plates can be prepared with thicknesses down to 4–8 µm, but measurement of small OH bands is currently limited by strong interference fringes for samples < 25 µm thick, precluding measurements of water within individual, finely recrystallized grains. By translating specimens under the 10 µm IR beam by steps of 10 to 50 µm, using a software-controlled x-y stage, spectra have been collected over specimen areas of nearly 4.5 mm2. This technique allowed us to separate and quantify broad OH bands due to fluid inclusions in quartz and OH bands due to micas and map their distributions in quartzites from the Moine Thrust (Scotland) and Main Central Thrust (Himalayas).

    Mylonitic quartzites deformed under greenschist facies conditions in the footwall to the Moine Thrust (MT) exhibit a large and variable 3400 cm-1 OH absorption band due to molecular water, and maps of water content corresponding to fluid inclusions show that inclusion densities correlate with deformation and recrystallization microstructures. Quartz grains of mylonitic orthogneisses and

  17. Experimental deformation in sandstone, carbonates and quartz aggregate

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, Cecilia See Nga [Stony Brook Univ., NY (United States)

    2015-05-01

    The first part of my thesis is mainly focused on the effect of grain size distribution on compaction localization in porous sandstone. To identify the microstructural parameters that influence compaction band formation, I conducted a systematic study of mechanical deformation, failure mode and microstructural evolution in Bleurswiller and Boise sandstones, of similar porosity (~25%) and mineralogy but different sorting. Discrete compaction bands were observed to develop over a wide range of pressure in the Bleurswiller sandstone that has a relatively uniform grain size distribution. In contrast, compaction localization was not observed in the poorly sorted Boise sandstone. My results demonstrate that grain size distribution exerts important influence on compaction band development, in agreement with recently published data from Valley of Fire and Buckskin Gulch, as well as numerical studies. The second part aimed to improve current knowledge on inelastic behavior, failure mode and brittle-ductile transition in another sedimentary rock, porous carbonates. A micritic Tavel (porosity of ~13%) and an allochemical Indiana (~18%) limestones were deformed under compaction in wet and dry conditions. At lower confining pressures, shear localization occurred in brittle faulting regime. Through transitional regime, the deformation switched to cataclastic flow regime at higher confining pressure. Specifically in the cataclastic regime, the (dry and wet) Tavel and dry Indiana failed by distributed cataclastic flow, while in contrast, wet Indiana failed as compaction localization. My results demonstrate that different failure modes and mechanical behaviors under different deformation regimes and water saturation are fundamental prior to any geophysical application in porous carbonates. The third part aimed to focus on investigating compaction on quartz aggregate starting at low (MPa) using X-ray diffraction. We report the diffraction peak evolution of quartz with increasing

  18. Fold-controlled quartz textures in the Pennine Mischabel backfold near Zermatt, Switzerland

    Science.gov (United States)

    Lebit, Hermann; Klaper, Eva M.; Lüneburg, Catalina M.

    2002-11-01

    Quartz fabric analyses along the basal thrust of the Dent Blanche nappe and in the footfall Pennine units indicate south directed thrusting for the last stage of Austro-alpine/Pennine nappe emplacement. Quartz fabrics—in particular, those from the Pennine Mischabel backfold—imply complex spatial and temporal texture developments with crystallographic preferred orientations (CPO) that are commonly in disagreement with mesoscopic grain shape lineations. In consequence, kinematic directions inferred by quartz textures do not necessarily coincide with those predicted by mesoscopic structural elements such as grain shape lineations. In our particular case, orientation of grain shape lineations is rather complex in the study area, while principal axes inferred from the quartz textures remain geographically constant, and exhibit a simple geometric relationship to the Mischabel backfold. It is suggested that the grain shape lineations correspond to the total accommodated (finite) strain whereas the quartz fabrics reflect late increments of deformation. Quartz CPOs in the hinge of the Mischabel fold are similar to those along the thrust, revealing asymmetric single girdles to c-axes point maxima. Subgrain rotation is the predominant recrystallization mechanism, suggesting steady state conditions in fabric development during progressive rotational deformation. In contrast, asymmetric cross girdles dominate the upper limb and uneven small circle c-axes distributions characterize the lower limb, although recrystallization in both limbs is characterized by grain boundary migration. This clear separation of quartz textures and recrystallization (deformation) mechanism conflicts with the common view on heterogeneous deformation patterns in folds where the major component of rotational shear is expected in the fold limbs. Our study suggests that fabric development in the limbs of the recumbent Mischabel fold was reset during progressive deformation shortly prior to the

  19. Limits to depletion of blue-green light stimulated luminescence in feldspars: Implications for quartz dating

    DEFF Research Database (Denmark)

    Jain, M.; Singhvi, A.K.

    2001-01-01

    -red stimulation at elevated temperature (220 degreesC) (ETIR) permits depletions of charges in Type (A) and Type (B) to the extent that the feldspar BGSL can be reduced by up to 97% in 5 min. These results offer prospects for (1) improved precision in paleodose estimates based on quartz; (2) BGSL dating of quartz...... in a polyminerallic fine grain samples; (3) age estimates based on both quartz and feldspars from the same aliquots, and (4) dating based on feldspar micro-inclusions. (C) 2001 Elsevier Science Ltd. All rights reserved....

  20. Use of the LM-OSL technique for the detection of partial bleaching in quartz

    DEFF Research Database (Denmark)

    Larsen, N.A.; Bulur, E.; Bøtter-Jensen, L.

    2000-01-01

    We present a study of the sensitivity to light (ease-of-bleaching) of the trapped charge in sedimentary quartz grains using an optically stimulated luminescence (OSL) technique in which the intensity of the stimulation light is linearly increased during the measurement period. The technique...... is known as linear modulation OSL (LM-OSL). In controlled laboratory conditions, this technique has been employed to study the ease-of-bleaching of the trapped charge in quartz by comparing the OSL curves of quartz aliquots which have been either: (1) fully bleached, followed by a laboratory dose of beta...

  1. General characteristics of quartz arenite types and their role in the recognition of sequence stratigraphic boundaries in ancient coastal and near shore sediments. A case study from Egypt and Saudi Arabia

    Science.gov (United States)

    Khalifa, M. A.

    2017-06-01

    Quartz arenites are useful in the recognition of depositional sequences and cycle boundaries in ancient coastal and near shore facies. In this study two types of quartz arenite are recognized: 1) depositional quartz arenite (calcareous, dolomitic, ferruginous and kaolinitic quartz arenites), and 2) diagenetic quartz arenite (orthoquartzite, siliceous quartz arenite, compact quartz arenite, and dedolomitic quartz arenite). Depositional quartz arenite often occurs on the tops (upper boundaries) of the depositional sequences that are bounded by sequence boundaries (with or without evidence of subaerial exposure) or correlative conformity surfaces that mark the change from forced regression to lowstand normal regression. Therefore, depositional quartz arenite can define the upper boundaries of third and fourth-order depositional sequences, cycle bases and tops (boundaries) within lowstand, transgressive and highstand systems tracts. Diagenetic quartz arenite (orthoquartzite, siliceous quartz arenite and dedolomitic quartz arenite) usually occurs at the tops (upper boundaries) of depositional sequences that have subaerial sequence boundary and have been subjected to prolonged subaerial weathering and hence is closely associated with subaerial unconformity sequence boundary surfaces and consequently indicates a sharp drop in sea level. Thus, diagenetic quartz arenite types can be used to recognize the tops (upper boundaries) of first and second-order depositional sequences. Compact quartz arenite that is considered the fourth type of diagenetic quartz arenite consists entirely of packed quartz grains, but lacking cement, occurs at the base of each fining-upward cycle (lower boundaries) in lowstand systems tracts and may define the bases of some different-order depositional sequences.

  2. Laser welding of fused quartz

    Science.gov (United States)

    Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

    2003-06-10

    Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

  3. Quartz types, authigenic and detrital, in the Upper Cretaceous Eagle Ford Formation, South Texas, USA

    Science.gov (United States)

    Milliken, Kitty L.; Ergene, Suzan M.; Ozkan, Aysen

    2016-06-01

    Lithologic heterogeneity of the Eagle Ford Formation in South Texas arises from mixing of extrabasinal grains of siliciclastic composition with intrabasinal grain assemblages composed dominantly of marine carbonate with a lesser component of biosiliceous debris. Detrital quartz in particular is derived from both extrabasinal and intrabasinal sources, posing a challenge for the use of bulk compositional data for mudrock classification. Extrabasinal detrital quartz supplied along a major axis of siliciclastic influx, the Woodbine depositional system of East Texas, is reduced to a minor part of the grain assemblage in South Texas. Petrographic evidence and point-count results indicate that around 85 percent of total quartz in these rocks, equal to about 12.6 volume percent, is authigenic. Thus, significant quantities of authigenic silica are not restricted to siliceous mudrocks, but can be found in carbonate-rich mudrocks as well. Formerly opaline skeletons of radiolaria, the dominant source of silica for authigenic quartz precipitation, are only poorly preserved by replacements including calcite, dolomite, pyrite, and quartz. Dissolved silica released by dissolution of radiolarians, and perhaps also by volcanic glass dissolution is re-precipitated in a variety of forms, including matrix-dispersed microquartz cement, fillings within primary intragranular pores, and grain replacement of both calcareous and siliceous allochems. The mass balance of dissolved silica mobilized from radiolarians and other reactive silicates and the precipitation of authigenic quartz is uncertain because the initial volumes of now-dissolved detrital material versus the final volume of authigenic material (quartz and other authigenic silicates) cannot be determined with accuracy.

  4. Laser direct synthesis of graphene on quartz

    OpenAIRE

    Wei, Dapeng; Mitchell, James I.; Tansarawiput, Chookiat; Nam, Woongsik; Qi, Minghao; Ye, Peide D.; Xu, Xianfan

    2013-01-01

    We demonstrate a laser-based technique to directly synthesize few layer graphene on quartz substrates without using any metal catalyst. In our approach, a photoresist S-1805 (from Shipley Comp.) film coated on quartz wafers was heated, and then decomposed, by irradiation of a continuous-wave laser. The carbon atoms from the photoresist were dissolved in the molten quartz, and then extracted to form graphene when the temperature of the quartz was decreased. Raman spectroscopy shows the as-prod...

  5. Sedimentological characteristics of Ajali sandstone in the Benin ...

    African Journals Online (AJOL)

    The major framework composition is Q95.6 F3.2 L1.2 which classifies the sandstone as Quartz arenite. Non-opaque heavy minerals constitute 13% of the entire heavy mineral suite of which ZTR index is 87%. The grains are texturally immature as depicted by their subangular edges but mineralogically mature in terms of ...

  6. Developing a SAR TT-OSL protocol for volcanically-heated aeolian quartz from Datong (China)

    DEFF Research Database (Denmark)

    Liu, Jinfeng; Murray, Andrew S.; Jain, Mayank

    2012-01-01

    The thermally-transferred optically stimulated luminescence (TT-OSL) responses of chemically-purified fine-grained quartz from a lava-baked aeolian sediment from Datong (China) are presented. Our main focus is to examine the suitability of the test dose TT-OSL and OSL response to monitor sensitiv......The thermally-transferred optically stimulated luminescence (TT-OSL) responses of chemically-purified fine-grained quartz from a lava-baked aeolian sediment from Datong (China) are presented. Our main focus is to examine the suitability of the test dose TT-OSL and OSL response to monitor...... with the test dose TT-OSL signal. The revised SAR TT-OSL protocol was tested by dose recovery tests on two very young (quartz OSL De20% of the given dose) in this revised SAR TT-OSL protocol....

  7. Vibration Resistant Quartz Crystal Resonators.

    Science.gov (United States)

    1981-01-01

    occurred and the ribbon eventually pulled edge metallization and quartz from the crystal mounting flat. LI P-I We attempted to anneal the ribbon ourselves...improvement in radiation resistance of the ’SC’ over the ’AT’. ,_/ __ In order to produce a successful SC crystal/ unit, i.e., one that exploits this...7--. .7 -- 1 x~ -7 7: Vida F4Y)A 3 -76 NN - -L3 43-i~ 3 ~ : . -- _____ ____ r ~ - - ____ _ _ _ _ 7-:7 7~ -4~l F-0 d-N I - - . - 7 71 --14A -77- :1

  8. SORPTION AND DISPERSION OF STRONTIUM RADIONUCLIDE IN THE BENTONITE-QUARTZ-CLAY AS BACKFILL MATERIAL CANDIDATE ON RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Herry Poernomo

    2010-12-01

    Full Text Available The experiment of sorption and dispersion characteristics of strontium in the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz as candidate of raw material for backfill material in the radioactive waste repository has been performed. The objective of this research is to know the grain size effect of bentonite, clay, and quartz on the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to-quartz can be gives physical characteristics of best such as bulk density (rb, effective porosity (e, permeability (K, best sorption characteristic such as distribution coefficient (Kd, and best dispersion characteristics such as dispersivity (a and effective dispersion coefficient (De of strontium in the backfill material candidate. The experiment was carried out in the column filled by the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz with the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to quartz of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 respectively at saturated condition of water, then flowed 0.1 N Sr(NO32 as buffer solution with tracer of 0.05 Ci/cm3 90Sr as strontium radionuclide simulation was leached from immobilized radioactive waste in the radioactive waste repository. The concentration of 90Sr in the effluents represented as Ct were analyzed by Ortec b counter every 30 min, then by using profile concentration of Co and Ct, values of Kd, a and De of 90Sr in the backfill material was determined. The experiment data showed that the best results were -80+120 mesh grain size of bentonite, clay, quartz respectively on the weight percent ratio of bentonite to clay to quartz of 70/10/20 with physical characteristics of rb = 0.658 g/cm3, e = 0.666 cm3/cm3, and K = 1.680x10-2 cm/sec, sorption characteristic of Kd = 46.108 cm3/g, dispersion characteristics of a = 5.443 cm, and De = 1.808x10-03 cm2/sec can be proposed as candidate of raw material of backfill material

  9. Grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1991-01-01

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990--February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: Study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  10. Grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    The present document is a progress report describing the work accomplished to date during the second year of our four-year grant (February 15, 1990 to February 14, 1994) to study grain boundaries. The research was focused on the following three major efforts: study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; study of short-circuit diffusion along grain boundaries; and development of a Thin-film Deposition/Bonding Apparatus for the manufacture of high purity bicrystals.

  11. Fundamental investigations of natural and laboratory generated SAR dose response curves for quartz OSL in the high dose range

    DEFF Research Database (Denmark)

    Timar-Gabor, Alida; Constantin, Daniela; Buylaert, Jan-Pieter

    2015-01-01

    saturation much earlier. Analysis of time resolved spectra indicated similar luminescence lifetimes for both fine and coarse quartz grains, and natural and laboratory generated OSL signals seem to use the same non-dosedependent recombination pathways. The natural signals of a sample with an expected......SAR-OSL investigations on quartz from Romanian loess resulted in non concordant fine and coarse-grain ages for equivalent doses higher than ~100 Gy. The laboratory dose response for both grain sizes is well represented by a sum of two saturating exponential functions, fine and coarse grains...... equivalent dose of 2000e2500 Gy were found to be below the saturation level of the laboratory dose response curve for both grain sizes; this also applied to the luminescence signals measured after >5000 Gy given on top of natural doses. © 2015 Elsevier Ltd. All rights reserved....

  12. Growth of multicrystalline silicon ingot with both enhanced quality and yield through quartz seeded method

    Science.gov (United States)

    Zhang, Huali; You, Da; Huang, Chunlai; Wu, Yihua; Xu, Yan; Wu, Peng

    2016-02-01

    An effective method for ingot quality control in directional solidification by using artificially designed quartz coating as seed is demonstrated in this paper. Quartz powders sprayed at the bottom of the crucible provided numerous nucleation points for the silicon grain growth. The quartz seeded growth ingot showed a large number of small and uniform silicon grains at the bottom, although the grain size increased with crystal growth. Comparatively less dislocation agglomerates and multiplication rate through bottom to top were observed through photoluminescence (PL) analysis. Crystals produced by quartz seeded method showed a higher and more uniform minority carrier lifetime distribution compared to that produced from normal method without seed, and shorter low lifetime area length at the bottom compared to that produced from mc-Si seed-assisted growth method, indicating larger production yield under the same feedstock charging weight. An enhanced average solar cell conversion efficiency of as high as 0.52% in absolute value was obtained compared to that made from seedless method under the same cell manufacture process line, very close to that made from mc-Si seed-assisted growth method.

  13. Shear enhanced compaction-solution bands in quartz-rich calcarenites of the Cotiella Massif (Spanish Pyrennes)

    Science.gov (United States)

    Tavani, Stefano; Granado, Pablo; Cantanero, Irene; Balsamo, Fabrizio; Corradetti, Amerigo; Muñoz, Josep

    2017-04-01

    In this contribution we describe deformation bands developed due to the interplay between shearing and mechanical and chemical compaction in Paleocene quartz-rich calcarenites. The studied structures are located in the footwall of the Cotiella Thrust (Spanish Pyrennes) and form anastomosed, mm-thick tabular bands, composed of high concentration of quartz grains. The bands strike perpendicular to the local transport direction of the regional thrust sheet, thus indicating a tectonic origin, and are organized in three sets. One set is perpendicular to the shallow-dipping bedding surface, while the other two are roughly perpendicular to each other and form an angle of 45°, in opposite directions, with the bedding. No macroscopic evidence of shearing is found along these bands. Optical microscope and SEM investigations on both undeformed and deformed rocks indicate that the high concentration of quartz within the deformation bands was caused by the localized pressure-enhanced dissolution of calcite grains, which determined the enrichment of the less soluble quartz grains. Quartz grains fracturing, fragmentation and crushing was observed along in all deformation bands, whereas cataclasis and shear occurs only along oblique oblique-to-bedding sets. All these features indicate that studied deformation bands are hybrid structures most likely developed during layer-parallel shortening. In detail, bedding perpendicular and bedding oblique structures can be interpreted as pure compaction and shear-enhanced compaction bands, respectively.

  14. Development of Quartz Fiber Calorimetry

    CERN Multimedia

    2002-01-01

    % RD40 \\\\ \\\\ Very Forward Calorimeters (VFCs) in LHC detectors should cover the pseudorapidity range from $\\eta$~=~2.5 to at least $\\eta$~=~5 in order to compute missing transverse energy and for jet tagging. Operation at such high rapidity requires the use of a calorimetry technique that is very radiation resistant, fast and insensitive to radioactivity (especially to neutrons). This can be accomplished through the Quartz-Calorimeter~(Q-Cal) concept of embedding silica core fibers, that resist to the Gigarad radiation level, into an absorber. In this calorimeter the shower particles produce light through the Cherenkov effect generating a signal less than 10~ns in duration. Unique to this new technology the visible energy of hadronic showers has a transverse dimension nearly an order of magnitude smaller than that in conventional calorimeters, enabling precise spatial resolution, sharper isolation cuts and better jet recognition against the minimum bias events background. Last but not least, most radioactive ...

  15. The Quartz Analog Watch: A Wonder Machine.

    Science.gov (United States)

    Crane, H. Richard, Ed.

    1993-01-01

    Summarizes how a quartz watch works. Discusses the quartz crystal, its form, and how its frequency is set to a standard; the integrated circuit chip that drives the crystal in vibration, scales its frequency down, and forms pulses that turn the motor; and the motor that drives the gear train that turns the hands. (ZWH)

  16. Optically stimulated exoelectron emission processes in quartz: comparison of experiment and theory

    DEFF Research Database (Denmark)

    Pagonis, V.; Ankjærgaard, Christina; Murray, A.S.

    2009-01-01

    Recent experiments have demonstrated that it is possible to measure optically stimulated exoelectron emission (OSE) signals simultaneously with optically stimulated luminescence (OSL) from quartz samples. These experiments provide valuable information on the charge movement in quartz grains. Two...... specific experiments measured the temperature dependence of the OSL and OSE signals on preheat and stimulation temperature. This paper provides a quantitative description of these experiments by using a previously published theoretical model for photostimulated exoelectron emission (PSEE). The experimental...... data yield a value of χ1.2 eV for the work function of quartz. The experimental temperature dependence of the OSE signals is interpreted on the basis of a photo-thermostimulated (PTSEE) process involving the main OSL trap at 320 °C; this process takes place with a thermal assistance energy estimated...

  17. Shock-metamorphic petrography and microRaman spectroscopy of quartz in upper impactite interval, ICDP drill core LB-07A, Bosumtwi impact crater, Ghana

    Science.gov (United States)

    Morrow, Jared R.

    Standard and universal stage optical microscope and microRaman spectroscopic examination of quartz from the upper impactite interval of the International Continental Scientific Drilling Program (ICDP) Lake Bosumtwi crater drill core LB-07A demonstrates widespread but heterogeneous evidence of shock metamorphism. In the upper impactite, which comprises interbedded polymict lithic breccia and suevite from a drilling depth of 333.4-415.7 m, quartz occurs as a major component within metasedimentary lithic clasts and as abundant, isolated, single-crystal grains within matrix. The noted quartz shock-metamorphic features include phenomena related to a) deformation, such as abundant planar microstructures, grain mosaicism, and reduced birefringence; b) phase transformations, such as rare diaplectic quartz glass and very rare coesite; c) melting, such as isolated, colorless to dark, glassy and devitrified vesicular melt grains; and d) secondary, post-shock features such as abundant, variable decoration of planar microstructures and patchy grain toasting. Common to abundant planar deformation features (PDFs) in quartz are dominated by -equivalent crystallographic planes, although significant percentages of and other higher index orientations also occur; notably, c(0001) planes are rare. Significantly, the quartz PDF orientations match most closely those reported elsewhere from strongly shocked, crystalline-target impactites. Barometry estimates based on quartz alteration in the upper impactite indicate that shock pressures in excess of 20 GPa were widely reached; pressures exceeding 40-45 GPa were more rare. The relatively high abundances of decorated planar microstructures and grain toasting in shocked quartz, together with the nature and distribution of melt within suevite, suggest a water- or volatile-rich target for the Bosumtwi impact event.

  18. Retrospective dosimetry: Dose evaluation using unheated and heated quartz from a radioactive waste storage building

    DEFF Research Database (Denmark)

    Jain, M.; Bøtter-Jensen, L.; Murray, A.S.

    2002-01-01

    In the assessment of dose received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites and particu......In the assessment of dose received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites...... and particularly in nuclear installations. These materials contain natural dosemeters Such as quartz. which usually is less sensitive than its heated counterpart. The potential of quartz extracted from mortar in a wall of a low-level radioactive-waste storage facility containing distributed sources of Co-60 and Cs......-137 has been investigated. Dose-depth profiles based on small aliquots and single grains from the quartz extracted from the mortar samples are reported here. These are compared with results from heated quartz and polymineral fine grains extracted from an adjacent brick, and the integrated dose...

  19. Fabrication of a novel quartz micromachined gyroscope

    Science.gov (United States)

    Xie, Liqiang; Xing, Jianchun; Wang, Haoxu; Wu, Xuezhong

    2015-04-01

    A novel quartz micromachined gyroscope is proposed in this paper. The novel gyroscope is realized by quartz anisotropic wet etching and 3-dimensional electrodes deposition. In the quartz wet etching process, the quality of Cr/Au mask films affecting the process are studied by experiment. An excellent mask film with 100 Å Cr and 2000 Å Au is achieved by optimization of experimental parameters. Crystal facets after etching seriously affect the following sidewall electrodes deposition process and the structure's mechanical behaviours. Removal of crystal facets is successfully implemented by increasing etching time based on etching rate ratios between facets and crystal planes. In the electrodes deposition process, an aperture mask evaporation method is employed to prepare electrodes on 3-dimensional surfaces of the gyroscope structure. The alignments among the aperture masks are realized by the ABM™ Mask Aligner System. Based on the processes described above, a z-axis quartz gyroscope is fabricated successfully.

  20. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    Science.gov (United States)

    Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2014-01-01

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis. PMID:24686729

  1. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    Directory of Open Access Journals (Sweden)

    Pietro Patimisco

    2014-03-01

    Full Text Available A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

  2. Electronic dipole resonance in smoky quartz

    NARCIS (Netherlands)

    Kerssen, J.; Volger, J.

    1967-01-01

    Microwave absorption in smoky quartz mono-crystal is ascribed to resonance transitions of trapped electrons between initially configurational degenerated states, which are Stark-splitted by a polarizing electric field.

  3. Quartz-enhanced photoacoustic spectroscopy: a review.

    Science.gov (United States)

    Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2014-03-28

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

  4. Quartz Mountain/Oklahoma Summer Arts Institute.

    Science.gov (United States)

    Frates, Mary Y.; Madeja, Stanley S.

    1982-01-01

    Describes the Quartz Mountain Oklahoma Summer Arts Institute program. It is designed to nurture artistic talent and to provide intensive arts experiences in music, dance, theater, and the visual arts for talented students aged 14-18. (AM)

  5. Thermal neutron diffusion cooling in wet quartz

    Energy Technology Data Exchange (ETDEWEB)

    Drozdowicz, K. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland)]. E-mail: krzysztof.drozdowicz@ifj.edu.pl; Krynicka, E. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Crakcw (Poland); Dabrowska, J. [Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland)

    2007-07-15

    The thermal neutron diffusion parameters of a rock material depend on the rock matrix itself and on the water content. The effect has been studied in quartz by Monte Carlo (MC) simulations of the variable buckling experiment for nine series of samples. A hyperbolic dependence of the density-removed diffusion cooling coefficient on the water content shows a variability of this parameter by two orders of magnitude. The function obtained for wet quartz is compared with the analogous dependence for wet dolomite.

  6. Quartz-superconductor quantum electromechanical system

    OpenAIRE

    Woolley, M. J.; Emzir, M. F.; Milburn, G. J.; Jerger, M.; Goryachev, M.; Tobar, M. E.; Fedorov, A.

    2016-01-01

    We propose and analyse a quantum electromechanical system composed of a monolithic quartz bulk acoustic wave (BAW) oscillator coupled to a superconducting transmon qubit via an intermediate LC electrical circuit. Monolithic quartz oscillators offer unprecedentedly high effective masses and quality factors for the investigation of mechanical oscillators in the quantum regime. Ground-state cooling of such mechanical modes via resonant piezoelectric coupling to an LC circuit, which is itself sid...

  7. Quartz-Enhanced Photoacoustic Spectroscopy: A Review

    OpenAIRE

    Pietro Patimisco; Gaetano Scamarcio; Tittel, Frank K.; Vincenzo Spagnolo

    2014-01-01

    A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimen...

  8. DISPERSION AND SORPTION CHARACTERISTICS OF URANIUM IN THE ZEOLITE-QUARTZ MIXTURE AS BACKFILL MATERIAL IN THE RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Herry Poernomo

    2010-06-01

    Full Text Available The experiment of sorption and dispersion characteristics of uranium in the zeolite-quartz mixture as candidate of raw material of backfill material in the radioactive waste repository has been performed. The objective is to know the effect of zeolite and quartz grain size on the zeolite-to-quartz weight ratio that gives porosity (ε, permeability (K, and dispersivity (α of uranium in the zeolite-quartz mixture as backfill material. The experiment was carried out by fixed bed method in the column filled by the zeolite-quartz mixture with zeolite-to-quartz weight percent ratio of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 wt. % in the water saturated condition flowed by uranyl nitrate solution of 500 ppm concentration (Co as uranium simulation which was leached from immobilized radioactive waste in the repository. The concentration of uranium in the effluents represented as Ct were analyzed by spectrophotometer Corning Colorimeter 253 every 15 minutes, then using Co and Ct uranium dispersivity (α in the backfill material was determined. The experiment data shown that 0.196 mm particle size of zeolite and 0.116 mm particle size of quartz on the zeolite-to-quartz weight ratio of 60/40 wt. % with ε = 0.678, K = 3.345x10-4 cm/second, and α = 0.759 cm can be proposed as candidate of raw material of backfill material in the radioactive waste repository.   Keywords: backfill material, quartz, radioactive waste, zeolite

  9. Quartz-coesite-stishovite relations in shocked metaquartzites from the Vredefort impact structure, South Africa

    Science.gov (United States)

    Spray, John G.; Boonsue, Suporn

    2018-01-01

    Coesite and stishovite are developed in shock veins within metaquartzites beyond a radius of 30 km from the center of the 2.02 Ga Vredefort impact structure. This work focuses on deploying analytical field emission scanning electron microscopy, electron backscattered diffraction, and Raman spectrometry to better understand the temporal and spatial relations of these silica polymorphs. α-Quartz in the host metaquartzites, away from shock veins, exhibits planar features, Brazil twins, and decorated planar deformation features, indicating a primary (bulk) shock loading of >5 quartz. It is also developed in the matrix of the shock veins, where it is typically of smaller size (quartz. Stishovite also occurs as more blebby, subhedral to anhedral grains in the vein matrix (typically quartz clasts. This is followed by (2) arrival of the main shock front, which shocks to 35 GPa. This generates coesite in the clasts and in the matrix. (3) On initial shock release, the coesite partly reverts to a less dense SiO2 phase, which is now represented by microcrystalline quartz. (4) With continued release, stishovite forms euhedral needle clusters at solid-liquid interfaces and as anhedral crystals in the matrix. (5) With decreasing pressure-temperature, the matrix completes crystallization to yield a microcrystalline quasi-igneous texture comprising quartz-coesite-stishovite-kyanite-biotite-alkali feldspar and accessory phases. It is possible that the shock vein represents the locus of a thermal spike within the bulk shock, in which case there is no requirement for additional pressure (i.e., the bulk shock was ≃35 GPa). However, if that pressure was not realized from the main shock, then supplementary pressure excursions within the vein would have been required. These could have taken the form of localized reverberations from wave trapping, or implosion processes, including pore collapse, phase change-initiated volume reduction, and melt cavitation.

  10. Estimating Quartz Reserves Using Compositional Kriging

    Directory of Open Access Journals (Sweden)

    J. Taboada

    2013-01-01

    Full Text Available The aim of this study was to determine spatial distribution and volume of four commercial quartz grades, namely, silicon metal, ferrosilicon, aggregate, and kaolin (depending on content in impurities in a quartz seam. The chemical and mineralogical composition of the reserves in the seam were determined from samples collected from outcrops, blasting operations, and exploratory drilling, and compositional kriging was used to calculate the volume and distribution of the reserves. A more accurate knowledge of the deposit ensures better mine planning, leading to higher profitability and an improved relationship with the environment.

  11. Relationship between Degree of Deformation in Quartz and Silica Dissolution for the Development of Alkali-Silica Reaction in Concrete.

    Science.gov (United States)

    Tiecher, Francieli; Gomes, Marcia E B; Dal Molin, Denise C C; Hasparyk, Nicole P; Monteiro, Paulo J M

    2017-09-04

    This paper presents research on the influence of quartz deformation in aggregates for the development of the alkali-silica reaction in concrete and its relationship with silica dissolution. The study also compares these characteristics with the field behavior of such rocks in concrete. The paper proposes parameters to classify the different degrees of deformation of quartz. Transmission electron microscopy showed the presence of walls even in slightly deformed quartz, which indicate the presence of the internal paths available to react with the alkaline concrete pore solutions and point to the potential development of an alkali-silica reaction. The presence of the deformation bands in the quartz grains leads to the alkali aggregate reaction occurring more rapidly. The visible spectrophotometer test was performed to evaluate the dissolution potential of the different samples of deformed quartz, which confirmed that the reactivity of the quartz increases as the deformation of the crystalline structure increases. The parameters established in the present study could be verified by analyzing the behavior of reactive and innocuous aggregates from the buildings.

  12. Exposure vs toxicity levels of airborne quartz, metal and carbon particles in cast iron foundries.

    Science.gov (United States)

    Moroni, Beatrice; Viti, Cecilia; Cappelletti, David

    2014-01-01

    Aerosol dust samples and quartz raw materials from different working stations in foundry plants were characterized in order to assess the health risk in this working environment. Samples were analysed by scanning and transmission electron microscopy coupled with image analysis and microanalysis, and by cathodoluminescence spectroscopy. In addition, the concentration and the solubility degree of Fe and other metals of potential health effect (Mn, Zn and Pb) in the bulk samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Overall, the results indicate substantial changes in quartz crystal structure and texture when passing from the raw material to the airborne dust, which include lattice defects, non-bridging oxygen hole centres and contamination of quartz grains by metal and/or graphite particles. All these aspects point towards the relevance of surface properties on reactivity. Exposure doses have been estimated based on surface area, and compared with threshold levels resulting from toxicology. The possible synergistic effects of concomitant exposure to inhalable magnetite, quartz and/or graphite particles in the same working environment have been properly remarked.

  13. Oxygen isotopic ratios in quartz as an indicator of provenance of dust

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, M L

    1977-01-01

    Quartz was isolated in the long range aerosol size range (fine silt, 1-10 ..mu..m in diameter) from atmospheric aerosols, wind-erosive soils, soil silts, shales, and Pacific pelagic sediments of the Northern and Southern Hemispheres, to trace their provenance or origin, as part of a study of dust mineral sequestering of /sup 137/Cs and other products of nuclear fission. The oxygen isotopic ratio (/sup 18/O//sup 16/O) was determined by mass spectrometry. The provenance has been established for this fine silt fraction which reflects the relative proportion of two classes of quartz source: (a) weathering of igneous and metamorphic rocks (high temperature origin and low /sup 18/O//sup 16/O ratio) and (b) of quartz crystallized in cherts and overgrowths (low temperature origin and high /sup 18/O//sup 16/O ratio). This quartz mixing ratio is a basic model or paradigm. Analyses of present day atmospheric aerosols and eolian-derived soils, Pacific pelagic sediments, and now-raised Phanerozoic marine sediments show that the Northern and Southern Hemispheres have separate large-scale reservoirs of the fine grain sizes that contribute to aerosol dusts. These can be identified by distinctive values of /sup 18/O//sup 16/O ratios of the quartz therein. The difference in quartz delta/sup 18/O value in parts per thousand per ml (/sup 0///sub 00/ of about 12 +- 2 /sup 0///sub 00/ in Southern Hemisphere mixed detrital sediments and about 19 +- 2 /sup 0///sub 00/ in those of the Northern Hemisphere (for constant size, the 1-10 ..mu..m size fraction) results from the presence of a considerably larger proportion of quartz having low-temperature origin and higher delta/sup 18/O values (chert, silica overgrowths, etc.) in the Northern Hemisphere reservoirs. The early paleoclimatic and paleogeochemical differences remain the control of the North-South Hemisphere difference in delta/sup 18/O values in long-range aerosol sized quartz.

  14. Geology of the Quartz Creek Pegmatite District, Gunnison County Colorado

    Science.gov (United States)

    Staatz, Mortimer H.; Trites, A.F.

    1952-01-01

    The Quartz Creek pegmatite district includes an area about 29 square miles in the vicinity of Quartz Creek in Gunnison County,. Colo. This area contains 1,803 pegmatites that are intruded into pre-Cambrian rocks.

  15. Evaluating flow laws for dynamically recrystallized quartz based on field data

    Science.gov (United States)

    Peters, Max; Herwegh, Marco

    2013-04-01

    The extrapolation of experimentally controlled deformation conditions, and the resulting relations between physical parameters acting during ductile deformation, to nature is considered controversial (see Herwegh et al., 2005 and references therein). Whereas the relationship between flow stress and recrystallized grain size can be empirically derived from lab experiments using paleopiezometers (e.g. Stipp & Tullis, 2003), the relation between recrystallized grain size, strain rate, differential stress, temperature and activation energy for dislocation creep requires further constraints. For these relations, various power law flow laws for dynamically recrystallized quartz were proposed over the past years (Paterson & Luan, 1990; Luan & Paterson, 1992; Gleason & Tullis, 1995; Hirth et al., 2001, Rutter & Brodie, 2004). The variations in the flow laws are mainly characterized by different starting materials, experimental conditions, the activation energy for dislocation creep and the stress exponent n. In this study we compare and evaluate experimentally derived flow laws regarding their reliability for the prediction of rheology of background deformation of naturally deformed crystalline samples from mylonites of the Aar massif (Swiss Central Alps). The majority of samples comprises highly deformed rocks (e.g. Central Aare granite), which exhibit severe grain size reduction. This reduction dominantly occurred by subgrain rotation (SGR), in the case of low temperature overprint by bulging recrystallization (BLG). Towards elevated temperatures, grain boundary migration (GBM) and SGR recrystallization were active. Along the metamorphic gradient (300 - 475°C) quartz microstructures and associated recrystallized grain size distributions indicate steady state mean grain sizes. The quantification of the metamorphic gradient (temperature, pressure, water fugacity) over the sampling area allowed the application of flow laws, yielding variations of 6 orders of magnitude in

  16. Evidence for a cosmogenic origin of fired glaciofluvial beds in the northwestern Andes: Correlation with experimentally heated quartz and feldspar

    Science.gov (United States)

    Mahaney, William C.; Krinsley, David; Kalm, Volli

    2010-11-01

    Fired sediment, considered equivalent to the 'Black Mat' impact of 12.9 ka, has been located and analyzed in the Andes of northwestern Venezuela. The 'Black Mat' refers to possible fallout from the Encke Comet airburst presumed to have occurred over the Laurentide Ice Sheet, the impact spreading ejecta over large portions of North America and Europe, making it an interhemispheric event of considerable magnitude. These possible equivalent beds in the northern Andes, first considered to result from a lightning-induced conflagration adjacent to the retreating Late Wisconsinan (Mérida Glaciation) ice, are now known to have undergone intense heating upon impact to a temperature much higher than what would occur in a wet, first-stage, successional tundra. Analyses carried out by SEM and FESEM, in SE and BSE modes, show massive micro-disruption on grain surfaces, fractures diminishing with depth toward grain interiors and C welded onto quartz and plagioclase minerals. Bubbles on some grains, possibly the result of exclusion of water-of-crystallization, are seen on some samples, principally quartz. The presence of copious monazite in the carbonaceous coatings is considered part of the incoming ejecta, as it is not a common indicator mineral in the local lithology. Analysis by SEM and FESEM of quartz and plagioclase subjected experimentally to temperatures ranging from 500 to 900 °C shows that intense heating affects resident mineralogies to differing extents, with grain disruption more prevalent along cleavage planes deep into grain interiors. The intergrowth of carbonaceous "black mat" material with thermally disrupted and fragmented quartz and feldspar, a "welded" patina of 100-400 nm thickness could only occur with temperatures in excess of 900 °C, the event interpreted here to be of cosmogenic origin.

  17. Texture measurements in fine grained polyphase aggregates

    Science.gov (United States)

    Kilian, R.; Heilbronner, R.; Stünitz, H.

    2009-04-01

    When analyzing natural and experimental microstructures, we routinely use the two methods for orientation imaging and texture measurements: (a) the computer-integrated polarization microscopy (CIP, Panozzo Heilbronner & Pauli, 1993) and (b) the electron back scatter diffractometry (EBSD, e.g. Kunze et al., 1994). The CIP method yields orientation maps and pole figures of c-axes (of uni-axial materials), while the EBSD method yields complete textural data for all crystallographic orientations. In order to compare the orientation images the Euler maps (obtained from EBSD) are recalculated and presented with the more intuitive colour look-up tables (CLUTs) of the CIP method. In this contribution we compare and contrast the results achieved by these two methods using two different samples taken from a metagranodiorite (Kilian et al., 2009): (1) a coarse grained mylonitic rock with polycrystalline quartz aggregates and (2) a very fine grained ultramylonitic rock with single quartz grains dispersed in a polymineralic matrix. For the coarse grained sample (1) both methods yield the same (strong) c-axis pole figure: the geometry of the c-axis polefigure as well as the texture intensity (maximum of polefigure) are identical. The texture of sample (2) - where small quartz grains are dispersed in the polymineralic matrix - is very weak to random. The CIP and EBSD c-axis pole figures are different and - as noted previously - these differences arise from a machine specific bias of the EBSD (Schmocker 2002). In addition to texture analysis, both methods are capable of image segmentation (identification and separation of individual grains in the orientation image) as well as shape and grain size analysis. However due to the entirely different approach taken, the results may differ significantly. For example, when deriving the grain size distribution for sample (2) EBSD (combined with with the OIM® analysis software) yields a positively skewed histogram (with the mode occurring

  18. Optimising the separation of quartz and feldspar optically stimulated luminescence using pulsed excitation

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Thomsen, Kristina Jørkov

    2010-01-01

    In luminescence dating, the two most commonly used natural minerals, quartz and feldspar, are exposed to different dose rates in the natural environment, and so record different doses. The luminescence signals also have different stabilities. For accurate dosimetry, the signals from these two...... minerals must be separated, either by physical separation of the mineral grains, or by instrumental separation of the luminescence signals. The luminescence signals from quartz and feldspar have different luminescence lifetimes under pulsed optical stimulation. This difference in lifetime can be used...... OSL intensity ratio is at a maximum. By using these parameters with an additional infrared (IR) stimulation at 175 °C before measurement (to further reduce the feldspar signal intensity), we obtain a factor of 25 enhancement in signal separation compared to that from a conventional prior-IR CW...

  19. Quartz exposure and increased respiratory symptoms among coal ...

    African Journals Online (AJOL)

    Quartz has been an inevitable composition of different type of coal mined. The quartz exposures among coalmine workers has been attributed to activities such as cutting the adjacent rock, the roof, the floor and the intrusions. Objective: The aim of the study is to determine the associations between quartz exposures and ...

  20. Fine-Grained Concrete of Composite Binder

    Science.gov (United States)

    Fediuk, R.; Pak, A.; Kuzmin, D.

    2017-11-01

    The article is devoted to the application of industrial wastes for the production of high-quality concretes with specified characteristics. The composite binders with low water demand (BLW) have been developed. Their strength is approximately twice the strength of the initial cement, and dilute BLW with 50 - 70% of the ground slag or quartz sand in their composition provide the same strength as the original Portland cement. It was proved that the quartzite sand screening can be used as a filler in the preparation of fine-grained concretes.

  1. Deformation Experiment on Quartz Aggregates with High Porosity and High Water Contents at High Pressure and Temperature

    Science.gov (United States)

    Okazaki, K.; Hirth, G.

    2016-12-01

    Large earthquakes typically nucleate near the depth limit of seismogenic zones. In these areas, high Vp/Vs ratios are commonly observed, indicating the presence of high pore fluid pressures. Thus, it is important to understand how the water content (both water in the crystal and in the pores) and the pore structure affect the rheology of polycrystalline materials. We conducted deformation experiments on quartz aggregates using a Griggs-type deformation apparatus. Samples were hot-pressed from silica gels, which contain 9 wt% water within the amorphous structure and absorbed on the surface. Hydrostatic experiments within the α-quartz stability field at a pressure of 1.5 GPa and 900°C indicate that hot-pressed samples are composed of quartz and no relict of amorphous material is present. The average grain size and porosity of the hot-pressed aggregates is about 4 μm and 23%, respectively. The grain shape is equigranular and no crystallographic preferred orientation (CPO) is observed. Initial results from general shear experiments on the hot-pressed quartz aggregates at the equivalent strain rate of 1.5 x 10-4 1/s, a pressure of 1.5 GPa and 900°C show very low strength (equivalent stress of 140 MPa) and nominally steady state flow at shear strains up to 3.5. The samples show no CPO and evidence for strain localization along R1 riedel shears. In contrast, deformation experiments on cores of quartzite show dislocation creep at this pressure/temperature condition. The measured stress from the new experiments is significantly lower than predicted by the wet quartz flow law (e.g., Hirth et al., 2001). The low flow stress and absence of CPO suggest the operation of grain-size sensitive flow, or perhaps that the effective pressure law is still applicable and the sample deforms by a distributed semi-brittle flow process

  2. The CMS forward calorimeter with quartz fibres

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    Part of the forward hadron calorimeter for the CMS experiment at the LHC is seen here. The calorimeter will be placed at the ends of the experiment barrel to measure the energy of particles produced in the 14 TeV proton-proton collisions. In consists of an iron absorber and specially designed radiation-hard quartz so that it survives the high radiation levels produced by collisions.

  3. Brittle-viscous deformation of vein quartz under fluid-rich low greenschist facies conditions

    Science.gov (United States)

    Jørgen Kjøll, Hans; Viola, Giulio; Menegon, Luca; Sørensen, Bjørn

    2015-04-01

    A coarse grained, statically crystallized quartz vein with a random CPO, embedded in a phyllonitic matrix, was studied by optical microscopy, SEM imaging and EBSD to gain insights into the processes of strain localization in quartz deformed under low greenschist facies conditions at the frictional-viscous transition. The vein is located in a high strain zone at the front of an imbricate stack of Caledonian age along the northwesternmost edge of the Repparfjord Tectonic Window in northern Norway. The vein was deformed within the Nussirjavrri Fault Zone (NFZ), an out-of-sequence thrust with a phyllonitic core characterized by a ramp-flat-ramp geometry, NNW plunging stretching lineations and top-to-the SSE thrusting kinematics. Deformation conditions are typical of the frictional-viscous transition. The phyllonitic core formed at the expense of metabasalt wherein feldspar broke down to form interconnected layers of fine, synkinematic phyllosilicates. In the mechanically weak framework of the phyllonite, the studied quartz vein acted as a relatively rigid body deforming mainly by coaxial strain. Viscous deformation, related to the development of a mesoscopic pervasive extensional crenulation cleavage, was accommodated within the vein initially by basal slip of suitably oriented quartz crystals, which produced e.g. undulose extinction, extinction bands and bulging grain boundaries. In the case of misoriented quartz crystals, however, glide-accommodated dislocation creep resulted soon inefficient and led to localized dislocation tangling and strain hardening. In response to 1) hardening, 2) progressive increase of fluid pressure within the actively deforming vein and 3) increasing competence contrast between the vein and the surrounding weak, foliated phyllonitic fault core, quartz crystals began to deform frictionally along specific lattice planes oriented optimally with respect to the imposed stress field. Microfaulting generated small volumes of gouge along

  4. Liquinert quartz crucible for the growth of multicrystalline Si ingots

    OpenAIRE

    Fujiwara, Kozo; Horioka, Yukichi; Sakuragi, Shiro

    2017-01-01

    The growth of a multicrystalline silicon (mc-Si) ingot for solar cell applications was attempted using a Liquinert quartz crucible. A mc-Si ingot was also grown in a quartz crucible coated with Si3N4 powder for comparison with that from the Liquinert quartz crucible. The mc-Si ingot grown in the Liquinert quartz crucible had a shinier surface which has few impurity particles and higher minority carrier lifetime than the mc-Si ingot grown in a quartz crucible coated with Si3N4 powder. These re...

  5. Sand and soil dynamics studied by quartz OSL dating

    Science.gov (United States)

    Wallinga, J.; Schilder, M.; van Mourik, J.

    2012-04-01

    Landscape evolution is the result of altering periods with active geomorphological processes and relatively stable periods with soil development. Soils and buried soils in polycyclic profiles are important indicators of landscape stability. Buried soils as micropodzols in polycyclic driftsand sequences are a common phenomena in driftsand landscapes. Insight in the age of the buried soils is of paramount importance to determine whether they indicate local or regional phases of landscape stability. However, accurate datingof palaeosols is often problematic. Here we investigate the use of optically stimulated luminescence (OSL) dating for determining the time, available for soil formation and duration of palaeosol formation. We studied young drift-sand deposits in the Weerterbergen area in SE-Netherlands. Samples were taken from six shallow pits (aeolian sand was samples both below and above a palaeosol. For comparison, the humic fraction of the palaeosols was dated with radiocarbon methods. OSL properties of the sand-sized quartz grains were suitable for luminescence dating. Internal consistency of results indicated that the wind-blown material was exposed sufficiently to daylight to entirely reset the OSL signal in all grains prior to deposition and burial. Results were in correct stratigraphic order, and showed that the sand deposits, and the sandwiched palaeosols, were formed during the past 200 years. The palaeosols were dated to different periods, and OSL ages suggested that the duration of soil formation was very short (< 10 years) in some cases. For all six sites, OSL ages were much younger than the radiocarbon ages on the humic soil fraction. The latter ranged from 100 to 1500 years. Further micro-morphological investigation of the palaeosols indicated the abundance of wind-blown organic material in the soils, partly originating from bronze-age hearths in the area. Combining this information with the OSL ages made clear that some of the 'palaeosols' consisted

  6. Evaluation of SAR procedures for D-e determination using single aliquots of quartz from two archaeological sites in South Africa

    CSIR Research Space (South Africa)

    Jacobs, Z

    2006-05-01

    Full Text Available irradiated quartz grains from two different archaeological sites in South Africa showed substantial changes in sensitivity through the measurement cycles; one sample (SIB2) showed no trend in D-e as a function of pre-heat temperature, showing...

  7. Thermodynamic properties of methane hydrate in quartz powder.

    Science.gov (United States)

    Voronov, Vitaly P; Gorodetskii, Evgeny E; Safonov, Sergey S

    2007-10-04

    Using the experimental method of precision adiabatic calorimetry, the thermodynamic (equilibrium) properties of methane hydrate in quartz sand with a grain size of 90-100 microm have been studied in the temperature range of 260-290 K and at pressures up to 10 MPa. The equilibrium curves for the water-methane hydrate-gas and ice-methane hydrate-gas transitions, hydration number, latent heat of hydrate decomposition along the equilibrium three-phase curves, and the specific heat capacity of the hydrate have been obtained. It has been experimentally shown that the equilibrium three-phase curves of the methane hydrate in porous media are shifted to the lower temperature and high pressure with respect to the equilibrium curves of the bulk hydrate. In these experiments, we have found that the specific heat capacity of the hydrate, within the accuracy of our measurements, coincides with the heat capacity of ice. The latent heat of the hydrate dissociation for the ice-hydrate-gas transition is equal to 143 +/- 10 J/g, whereas, for the transition from hydrate to water and gas, the latent heat is 415 +/- 15 J/g. The hydration number has been evaluated in the different hydrate conditions and has been found to be equal to n = 6.16 +/- 0.06. In addition, the influence of the water saturation of the porous media and its distribution over the porous space on the measured parameters has been experimentally studied.

  8. Experimental diagenesis of quartz with petroleum; Diagenese experimentale du quartz en presence d'hydrocarbures

    Energy Technology Data Exchange (ETDEWEB)

    Teinturier, St.

    2002-11-01

    Quartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. However, the possible cementation of quartz during petroleum emplacement is still debated. In most cases, the reconstitution and the understanding of diagenetic processes is based on fluid inclusions studies. However, many questions concerning the representativeness and the reading of the fluid inclusions still remains misunderstood. The experiments were carried out in a silica{+-}water{+-}salts{+-}oil{+-}gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system. Calibration curves have been established using Raman micro-spectroscopy and synthetic reference inclusions to calculate the methane content of aqueous inclusions in the H{sub 2}O-CH{sub 4}-NaCl system. A quantitative procedure for FT-IR micro-spectrometry has been developed to obtain, from individual petroleum fluid inclusions, mole % concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. Synthetic aqueous inclusions were created within quartz micro-fractures, with methane (from 150 deg C-200 bar), with petroleum (from 184 deg C-163 bar) and inside quartz overgrowth with the presence of hydrocarbons (from 277 deg C-300 bar). Synthetic petroleum inclusions were created with different water/oil ratios (W/O) within quartz micro-fractures (0quartz overgrowth (10

  9. Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals

    DEFF Research Database (Denmark)

    Murray, A.S.; Thomsen, Kristina Jørkov; Masuda, N.

    2012-01-01

    When dating older sedimentary deposits using quartz, there are no unambiguous methods for identifying the presence of incomplete bleaching. Current statistical analysis of dose distributions depends entirely on the assumption that incomplete bleaching and mixing are the main causes of any excess...... dispersion in the distribution; the only existing way to test this assumption is using independent age control. Here we suggest a new approach to this question, based on the differential bleaching rates of quartz and feldspar luminescence signals. We first present data that confirm the differences...... in relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar luminescence stimulated at 50 °C by infrared light (IR50) and feldspar luminescence stimulated at 290 °C by infrared light after a stimulation at 50 °C (pIRIR290), and use recently deposited samples to determine...

  10. Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

    OpenAIRE

    Yufei Ma; Guang Yu; Jingbo Zhang; Xin Yu; Rui Sun; Tittel, Frank K.

    2015-01-01

    A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 ?m continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0 ) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kH...

  11. Experimental Phase Functions of Millimeter-sized Cosmic Dust Grains

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, O.; Moreno, F.; Guirado, D.; Escobar-Cerezo, J. [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Vargas-Martín, F. [Department of Electromagnetism and Electronics, University of Murcia, E-30100 Murcia (Spain); Min, M. [SRON Netherlands Institute for Space Research, Sobornnelaan 2, 3584 CA Utrecht (Netherlands); Hovenier, J. W. [Astronomical Institute “Anton Pannekoek,” University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands)

    2017-09-01

    We present the experimental phase functions of three types of millimeter-sized dust grains consisting of enstatite, quartz, and volcanic material from Mount Etna, respectively. The three grains present similar sizes but different absorbing properties. The measurements are performed at 527 nm covering the scattering angle range from 3° to 170°. The measured phase functions show two well-defined regions: (i) soft forward peaks and (ii) a continuous increase with the scattering angle at side- and back-scattering regions. This behavior at side- and back-scattering regions is in agreement with the observed phase functions of the Fomalhaut and HR 4796A dust rings. Further computations and measurements (including polarization) for millimeter-sized grains are needed to draw some conclusions about the fluffy or compact structure of the dust grains.

  12. Production of quartz plates for CMS-CASTOR Experiment

    CERN Document Server

    Adiguzel, Aytul; Ayhan, Aydin; Bakirci, Mustafa Numan; Basegmez, Suzan; Beaumont, Willem; Borras, Kerstin; Campbell, Alan; De Paula Carvalho, W; Çerçi, Salim; De Jesus Damiao, Dilson; Dogangün, O; Dumanoglu, Isa; d'Enterria, David; Erchov, Y; Eskut, Eda; Figueiredo, D; Girgis, Semiray; Göttlicher, P; Gouskos, Loukas; Gurpinar, Emine; Hos, Ilknur; Katkov, Igor; Katsas, Panagiotis; Khein, Lev; Knutsson, Albert; Kuznetsov, Andrey; Lebeau, Michel; Van Mechelen, Pierre; Muhl, Carsten; Musienko, Yuri; Ochesanu, Silvia; Onengüt, G; Onengut, G Jr; Ozdemir, Kadri; Panagiotou, Apostolos; Polatoz, A; Ripert, Marion; Shileev, K; Sogut, Kenan; Tiflov, B TaliV; Kayis-Topaksu, A; Uzun, Dilber

    2008-01-01

    Light transmission rate performance of $102$ irradiated quartz samples was measured to select the best quartz plates for CMS-CASTOR calorimeter. All the produced quartz plates were originally used in a previous CERN experiment, DELPHI. Three different doses of $^{60}$Co source were used with the collaboration of PSI (Paul Scherrer Institute, Villigen PSI, Switzerland.) to study the transmission rate performance of the quartz samples after irradiation for different incident light, ranging from $250$ to $700$ nm in $5$ nm increasing steps. All samples show different decrease in the rate with wavelength for different doses. Three different steps were followed before irradiation to find out the best way of cleaning the original DELPHI Cu/Cr tracks on the samples. Results of these measurements presented here correspond to the quartz plates that will be used in one hadronic sector of CASTOR calorimeter until end of 2008. For the full calorimeter new quartz plates will be installed. We also present the light transmi...

  13. Luminescence sensitivity changes in quartz as a result of annealing

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Agersnap Larsen, N.; Mejdahl, V.

    1995-01-01

    Retrospective dosimetry using optically stimulated luminescence (OSL) on quartz extracted from (for example) bricks needs to account for strong OSL sensitivity changes that are known to occur depending on the previous thermal treatment of the sample. Non-heated quartz exhibits OSL orders...... of magnitude less per unit radiation than that for heated material. The reason these temperature-induced sensitivity changes occur in quartz is presently not well understood. This phenomenon is also seen in the related area of luminescence dating in which sedimentary quartz and quartz from heated...... archaeological samples show very different OSL sensitivities. In this paper we report on studies of the effect of high temperature annealing on the OSL and phototransferred TL (PTTL) signals from sedimentary and synthetic quartz. A dramatic enhancement of both OSL and PTTL sensitivity was found especially...

  14. Phase transitions in shocked porous quartz

    Science.gov (United States)

    Akin, M. C.; Crum, R. S.; Lind, J.; Pagan, D. C.; Homel, M. A.; Hurley, R. C.; Herbold, E. B.

    2017-06-01

    The presence of porosity in granular media provides the means to probe regions of the phase diagram that do not coincide with the principal Hugoniot. In particular, the potential for increased heating is likely to lead to observable changes in phase boundaries. 55% dense quartz and forsterite were prepared by tap filling. These samples were shock compressed using the two stage light gas gun at DCS-APS to examine the impact of the increased porosity on the phase boundary. Here we discuss the observed changes to phase in quartz and forsterite compared to the fully dense materials, the effects of porosity upon compaction and phase transitions, and the implications for constructing the phase diagram. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Work was supported by LLNL's LDRD program under Grant 16-ERD-010. The Dynamic Compression Sector (35) is supported by Department of Energy / National Nuclear Security Administration under Award Number DE-NA0002442. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

  15. Post-IR IRSL290 dating of K-rich feldspar sand grains in a wind-dominated system on Sardinia

    DEFF Research Database (Denmark)

    Andreucci, S.; Sechi, D.; Buylaert, Jan-Pieter

    2017-01-01

    block sand-sized grains for quartz SAR-OSL and K-feldspar pIRIR dating were collected. The natural quartz SAR-OSL sample lies below the saturation limit of the dose response curve (De ... with the quartz result. A further test on older samples was carried out on the sedimentary succession at Bue Marino cave, which includes a sandy wind-blown unit, enclosed between two calcareous crusts. U-series dates of crusts constrain the aeolianite formation between ∼130 and ∼86 ka. The quartz SAR-OSL signals....... The pIRIR290 ages indicate an offset up to ∼1000 years. We can conclude that the pIRIR290 method on sand-sized K-feldspar grains shows great promise for samples at or beyond the quartz OSL age limit but should not be applied to Late Holocene or modern deposits....

  16. OH-point defects in quartz in B- and Li-bearing systems and their application to pegmatites

    Science.gov (United States)

    Baron, M. A.; Stalder, R.; Konzett, J.; Hauzenberger, C. A.

    2015-01-01

    OH incorporation in quartz in Al-, B- and Li-bearing systems (granitic systems containing tourmaline or spodumene) was studied experimentally in order to investigate the effect of pressure, temperature and chemical impurities on the generation of OH-defects. High-pressure experiments were carried out at pressures between 5 and 25 kbar and temperatures between 800 and 900 °C, and OH-contents in quartz were calculated from IR absorption spectra measured on oriented quartz crystals. IR absorption features were assigned to impurity substitutions, such as AlOH (3,420, 3,379 and 3,315 cm-1) and BOH (3,595 cm-1), LiOH (3,483 cm-1), and hydrogarnet substitution (4H)Si defects (3,583 cm-1). Results indicate a negative correlation of incorporated Al-specific OH-defect content versus pressure (630 ± 130 wt ppm H2O at 5 kbar to 102 ± 6 wt ppm H2O at 25 kbar), but no clear correlation of B-specific OH-defects with pressure. In runs initially containing spodumene, virtually OH-free quartzes were observed at pressures ≥10 kbar, where impurity cations compensate each other forming an anhydrous eucryptite-defect component. In contrast, at 5 kbar, both Li- ad Al-specific OH-defects are observed (corresponding to 470 ± 75 wt ppm H2O). Results from this study may therefore be used to monitor formation conditions of quartz in terms of pressure and trace metal saturation of the crystallizing petrological system. IR spectra obtained from natural quartz grains from a tourmaline-bearing pegmatite exhibit B- and Al-related OH-bands. The B-related OH-band is also exhibited in quartz from a tourmaline + spodumene-bearing pegmatite. Li- and Al-related OH-bands, however, are subordinate or not observed at all in the spodumene-bearing system, which suggests that OH-vibrations do not reflect absolute Li-contents in quartz due to efficient coupled substitution involving Al. Data from experimental runs and natural specimens indicate that the B-related OH-band can be used as a rough proxy for

  17. Microbiota of kefir grains

    Directory of Open Access Journals (Sweden)

    Tomislav Pogačić

    2013-03-01

    Full Text Available Kefir grains represent the unique microbial community consisting of bacteria, yeasts, and sometimes filamentous moulds creating complex symbiotic community. The complexity of their physical and microbial structures is the reason that the kefir grains are still not unequivocally elucidated. Microbiota of kefir grains has been studied by many microbiological and molecular approaches. The development of metagenomics, based on the identification without cultivation, is opening new possibilities for identification of previously nonisolated and non-identified microbial species from the kefir grains. Considering recent studies, there are over 50 microbial species associated with kefir grains. The aim of this review is to summarise the microbiota composition of kefir grains. Moreover, because of technological and microbiological significance of the kefir grains, the paper provides an insight into the microbiological and molecular methods applied to study microbial biodiversity of kefir grains.

  18. Note: sensitivity multiplication module for quartz crystal microbalance applications.

    Science.gov (United States)

    Burda, Ioan; Silaghi, Andreea; Tunyagi, Arthur; Simon, Simion; Popescu, Octavian

    2014-02-01

    In this Note, a novel sensitivity multiplication module was added to classical quartz crystal microbalance (QCM). The purpose is to increase QCM frequency shift without changing nominal frequency of the quartz crystal resonator or nominal frequency value delivered to the frequency counter. Allan deviance measurement confirms that the multiplication of the frequency shift is limited by the quartz crystal loads with direct effect in quartz crystal quality factor and oscillator stability. An experimental implementation of this new sensitivity multiplication module that can increase up to six times the frequency shift of the QCM was experimentally investigated using different load conditions.

  19. Thermal conductivity measurements in porous mixtures of methane hydrate and quartz sand

    Science.gov (United States)

    Waite, W.F.; deMartin, B.J.; Kirby, S.H.; Pinkston, J.; Ruppel, C.D.

    2002-01-01

    Using von Herzen and Maxwell's needle probe method, we measured thermal conductivity in four porous mixtures of quartz sand and methane gas hydrate, with hydrate composing 0, 33, 67 and 100% of the solid volume. Thermal conductivities were measured at a constant methane pore pressure of 24.8 MPa between -20 and +15??C, and at a constant temperature of -10??C between 3.5 and 27.6 MPa methane pore pressure. Thermal conductivity decreased with increasing temperature and increased with increasing methane pore pressure. Both dependencies weakened with increasing hydrate content. Despite the high thermal conductivity of quartz relative to methane hydrate, the largest thermal conductivity was measured in the mixture containing 33% hydrate rather than in hydrate-free sand. This suggests gas hydrate enhanced grain-to-grain heat transfer, perhaps due to intergranular contact growth during hydrate synthesis. These results for gas-filled porous mixtures can help constrain thermal conductivity estimates in porous, gas hydrate-bearing systems.

  20. Optical and electrochemical properties of optically transparent, boron-doped diamond thin films deposited on quartz.

    Science.gov (United States)

    Stotter, Jason; Zak, Jerzy; Behler, Zack; Show, Yoshiuki; Swain, Greg M

    2002-12-01

    The optical and electrochemical properties of transparent, boron-doped diamond thin film, deposited on quartz, are discussed. The films were deposited by microwave-assisted chemical vapor deposition, for 1-2 h, using a 0.5% CH4/H2 source gas mixture at 45 Torr and 600 W of power. A high rate of diamond nucleation was achieved by mechanically scratching the quartz. This pretreatment leads to the formation of a continuous film, in a short period of time, which consists of nanometer-sized grains of diamond. The thin-film electrode was characterized by cyclic voltammetry, atomic force microscopy, and UV-visible absorption spectrophotometry. The film's electrochemical response was evaluated using Ru(NH3)6(3+/2+) in 1 M KCl, Fe(CN)6(3-/4-) in 1 M KCl, and chlorpromazine (CPZ) in 10 mM HClO4. The film exhibited a low voltammetric background current and a stable and active voltammetric response for all three redox systems. The optical transparency of the polycrystalline film in the visible region was near 50% and fairly constant between 300 and 800 nm. The optical and electrical properties were extremely stable during 48-h exposure tests in various aqueous (HNO3, NaOH) solutions and nonaqueous (e.g., chlorinated) solvents. The properties were also extremely stable during anodic and cathodic potential cycling in harsh aqueous environments. This stability is in stark contrast to what was observed for an indium-doped tin oxide thin film coated on quartz. The spectroelectrochemical response (transmission mode) for CPZ was studied in detail, using a thin-layer spectroelectrochemical cell. Thin-layer voltammetry, potential step/ absorption measurements, and detection analytical figures of merit are presented. The results demonstrate that durable, stable, and optically transparent diamond thin films, with low electrical resistivity (approximately 0.026 omega x cm) laterally through the film, can be deposited on quartz.

  1. A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications

    OpenAIRE

    Tomasz Starecki; Piotr Z. Wieczorek

    2017-01-01

    All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the ...

  2. Estimating average shock pressures recorded by impactite samples based on universal stage investigations of planar deformation features in quartz - Sources of error and recommendations

    Science.gov (United States)

    Holm-Alwmark, S.; Ferrière, L.; Alwmark, C.; Poelchau, M. H.

    2018-01-01

    Planar deformation features (PDFs) in quartz are the most widely used indicator of shock metamorphism in terrestrial rocks. They can also be used for estimating average shock pressures that quartz-bearing rocks have been subjected to. Here we report on a number of observations and problems that we have encountered when performing universal stage measurements and crystallographically indexing of PDF orientations in quartz. These include a comparison between manual and automated methods of indexing PDFs, an evaluation of the new stereographic projection template, and observations regarding the PDF statistics related to the c-axis position and rhombohedral plane symmetry. We further discuss the implications that our findings have for shock barometry studies. Our study shows that the currently used stereographic projection template for indexing PDFs in quartz might induce an overestimation of rhombohedral planes with low Miller-Bravais indices. We suggest, based on a comparison of different shock barometry methods, that a unified method of assigning shock pressures to samples based on PDFs in quartz is necessary to allow comparison of data sets. This method needs to take into account not only the average number of PDF sets/grain but also the number of high Miller-Bravais index planes, both of which are important factors according to our study. Finally, we present a suggestion for such a method (which is valid for nonporous quartz-bearing rock types), which consists of assigning quartz grains into types (A-E) based on the PDF orientation pattern, and then calculation of a mean shock pressure for each sample.

  3. Retrograde evolution of quartz segregations from the Dos Picos shear zone in the Nevado-Filabride Complex (Betic chains, Spain). Evidence from fluid inclusions and quartz c-axis fabrics

    Science.gov (United States)

    González-Casado, J. M.; Casquet, C.; Martínez-Martinez, J. M.; Garcia-Dueñas, V.

    1995-02-01

    Synkinematic quartz veins are ubiquitous in the shear zone separating the Veleta unit from the Calar Alto unit in the internal part of the Betic Cordilleras. They have been studied with respect to quartz c-axis fabrics, microstructures and fluid inclusions. Veins were probably generated during syn-metamorphic stacking of the units at P = 500 - 600 MPa and T = 400 - 500°C. Quartz displays two groups of microstructures in the shear zone: (1) older coarse-grained mosaics (CGM) resulting from exaggerated grain growth; and (2) younger fine-grained mosaics (FGM) developed at the expense of the former. The fine-grained mosaics show polygonal granoblastic and elongate mosaic microstructures in general, with ribbon microstructures often found near the boundary of the units. Fluids contained in secondary inclusions vary from high salinity brines to different types of CO2—brine mixtures and low density CO2 fluids. Differences in composition and P-T trapping conditions are indicated for the different types of inclusions. Some fluid inclusions are older than the FGM, whereas others are younger, thus constraining the P- T conditions at which the two microstructural events took place. Fluid inclusion evidence suggests conditions of Pfluid > 170 MPa and T ≧ 370-430°C for the CGM and Pfluid ≧ 20-80 MPa and T > 340°C for the FGM. The quartz c-axis fabrics dealt with here correspond to the second recrystallization event, as little evidence of older fabrics is preserved in the shear zone. C-axis patterns vary across the shear zone from slightly asymmetrical type I crossed girdles in the hanging wall and footwall to more asymmetrical crossed girdles at the boundary of the units. This indicates a correlative increase in the magnitude of the heterogeneous shear strain in the same direction. Most of the deformation is concentrated at the top of the Veleta unit. The sense of movement is top to the west, in agreement with other kinematic markers. The quartz c-axis fabrics resulted

  4. Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

    Directory of Open Access Journals (Sweden)

    Yufei Ma

    2015-03-01

    Full Text Available A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS is reported. A 1.395 μm continuous wave (CW, distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs with a resonant frequency (f0 of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

  5. Quartz enhanced photoacoustic spectroscopy based trace gas sensors using different quartz tuning forks.

    Science.gov (United States)

    Ma, Yufei; Yu, Guang; Zhang, Jingbo; Yu, Xin; Sun, Rui; Tittel, Frank K

    2015-03-27

    A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 μm continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

  6. Thermal quenching of thermoluminescence in quartz samples of various origin

    Energy Technology Data Exchange (ETDEWEB)

    Subedi, B. [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124-Thessaloniki (Greece); Oniya, E. [Archaeometry Laboratory, Cultural and Educational Technology Institute (C.E.T.I.), R.C. ' Athena' , Tsimiski 58, 67100 Xanthi (Greece); Physics and Electronics Department, Adekunle Ajasin University, PMB 01, Akungba Akoko (Nigeria); Polymeris, G.S. [ISIK University, Physics Department, Faculty of Science and Arts, 34980-Sile, Istanbul (Turkey); Afouxenidis, D.; Tsirliganis, N.C. [Archaeometry Laboratory, Cultural and Educational Technology Institute (C.E.T.I.), R.C. ' Athena' , Tsimiski 58, 67100 Xanthi (Greece); Kitis, G., E-mail: gkitis@auth.g [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124-Thessaloniki (Greece)

    2011-03-15

    The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.

  7. Electron irradiation damage effects in hydrothermal grown quartz ...

    African Journals Online (AJOL)

    Electron irradiation effects in synthetic quartz single crystals were investigated to determine the extent of damage of the crystals during transmission electron microscopy examination, as the rapid deterioration is of major concern. On exposure of the quartz crystals to electron flux of 3.0 x 108 e/cm2/s at 200 kV accelerating ...

  8. Quartz exposure in agriculture: literature review and South African survey.

    NARCIS (Netherlands)

    Swanepoel, A.J.; Rees, D.; Renton, K.; Swanepoel, C.; Kromhout, H.|info:eu-repo/dai/nl/074385224; Gardiner, K.

    2010-01-01

    OBJECTIVES: To review the published literature on respirable quartz exposure and associated disease in agricultural related settings systematically and to describe personal respirable dust and quartz measurements collected on a sandy soil farm in the Free State province of South Africa. METHODS: The

  9. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film.

    Science.gov (United States)

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong

    2016-09-06

    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone.

  10. A new irradiated quartz for beta source calibration

    DEFF Research Database (Denmark)

    Hansen, Vicki; Murray, Andrew Sean; Buylaert, Jan-Pieter

    2015-01-01

    laboratories have used the various different batches of Risø calibration quartz for the calibration of beta and X-ray sources, but these have been largely undescribed. Here we describe in detail the preparation and luminescence characteristics of a new quartz standard, based on a North Sea beach sand collected...

  11. New approaches in quartz-enhanced photoacoustic sensing

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Pennetta, Riccardo; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2015-01-01

    We report on the design and realization of custom quartz tuning forks with different geometries and sizes aimed to improve the photoacoustic effect in quartz-enhanced photoacoustic (QEPAS) sensor systems. A detailed analysis of the piezoelectric properties in terms of resonance frequencies, quality factors, gas damping was performed.

  12. Structural analysis and surface morphology of quartz | Jamo ...

    African Journals Online (AJOL)

    -ray diffraction (XRD) and scanning electron microscopy (SEM) were used to observe the surface and internal structure of the quartz. The results among other things revealed that the quartz consist of mainly silica (SiO2), with crystalline ...

  13. Surface textures of quartz grains from Goa coast - An application of the scanning electron microscope

    Digital Repository Service at National Institute of Oceanography (India)

    Ambre, N.V.; Gujar, A.R.; Mislankar, P.G.

    stream_size 12 stream_content_type text/plain stream_name Dev_Plan_Coast_Placer_Min_2005_121.pdf.txt stream_source_info Dev_Plan_Coast_Placer_Min_2005_121.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset...

  14. Surface microtextures of quartz grains from the central coast of Tamil Nadu

    Digital Repository Service at National Institute of Oceanography (India)

    Udayaganesan, P.; Angusamy, N.; Gujar, A.R.; Rajamanickam, G.V.

    into three sectors on the basis of drainage, geomorphology and nature of the beach and shelf topography. Surface textures of the northern sector display an array of mechanical features like conchoidal fracture, V marks and impact pits, indicating...

  15. Comparison of single-grain and small-aliquot OSL dose estimates in < 3000 years old river sediments from South India

    DEFF Research Database (Denmark)

    Thomas, P.J.; Jain, M.; Juyal, N.

    2005-01-01

    We report on OSL dose distributions derived from small-aliquot and single grains of quartz in young fluvial sediments sampled from the Penner River basin, South India. The single-grain dose distributions suggest that 13 out of 19 samples were well bleached. In many well-bleached samples, there wa...

  16. Peculiar Feldspar And Quartz Inclusions Within Zircons From Anorthosites, North Eastern Desert, Egypt

    Science.gov (United States)

    Eliwa, H. A.; Dawoud, M. I.; Khalaf, I. M.; Negendank, J. F.; Itaya, T.

    2004-12-01

    Zircons from three anorthosite outcrops along Wadi Dib area, north Eastern Desert of Egypt contain abundant and conspicuous inclusions of quartz, feldspar, amphibole and apatite. These anorthosites, as (50-100m thick) layers, represent the top of mafic-ultramafic intrusions exhibiting rhythmic layering visible by reputation of melanocratic and leucocratic layers. Field and microscopic studies exhibit that these anorthosites were affected by the action of residual magmatic solutions associated with the late stage crystallization of the younger granites, which modified their mineralogical composition. They are composed totally of plagioclase with subordinate amount of clinoenstatite, augite, amphibole, biotite, K-feldspar, and quartz. Accessories are magnetite, ilmenite, apatite and zircon. The abundance and the mode of occurrence of K-feldspar, quartz, and biotite with apatite and zircon among the megacrysts suggest their formation is ascribed to the interaction with the residual solutions. The microprobe data exhibit difference between feldspar and amphiboles contained herein zircons and those as anorthosite mineral constituents. The genetic relationship between zircons and their inclusions suggests later growth of zircons than inclusions and most probably at the final stage of rock modification. Zircons are magmatic and found in the interstitial feldspar and quartz among plagioclase megacrysts in aggregates or as individual grains. The microscopic and SEM images investigation exhibit that most zircons are subhedral to euhedral equant and prismatic crystals. Most zircons have same range of crystal morphologies and internal growth structures with predominance of prism /{100/} and pyramid /{101/} and occasionally prism /{110/} and pyramid /{111/}. No evidences for poly-faceted grains, inherited cores or later overgrowths were detected. CL images distinguished zircons with visible core-rim structures and others with regular and continuous growth zones contained herein

  17. The hydrolytic weakening effect in quartz

    Science.gov (United States)

    Hobbs, B. E.

    Experiments on single crystals of quartz have shown that an order of magnitude increase in the fugacity of H2O is associated with about an order of magnitude decrease in the flow strength at a given temperature and pressure. The classical interpretation of this hydrolytic weakening effect is that H2O groups are incorporated into the quartz structure as Si-OH.HO-Si groups. Then, in order to move a dislocation, OH.HO bonds need to be broken rather than Si-O bonds. The rate controlling process is envisaged as the diffusion of the (OH)-defect to or with the dislocation core. This paper discusses the manner in which charged hydrogen- or hydroxyl-defects alter the concentrations of other charged defects such as kinks and jogs on dislocations or vacancies and interstitials and so have an influence on the deformation rate. As an example, an increase in the concentration of negatively charged (OH)-defects leads to an increase in the concentration of positively charged kinks on dislocations thus increasing the strain rate. Other deformation mechanisms involving diffusion of oxygen and silicon with or without climb of dislocations or motion of kinks are also investigated and are shown to be capable of explaining the observed effect. This defect chemistry interpretation is consistent with the classical interpretation but also proposes other mechanisms where the direct diffusion of (OH)-defects plays no role in the process. As an example, an increase in the concentration of negatively charged (OH)-defects increases both the concentration of positively charged jogs and positively charged silicon interstitials in such a way as to explain the magnitude of the hydrolytic weakening effect. As such, the rate controlling process is the climb of dislocations controlled by silicon diffusion, not the diffusion of (OH)-defects. Although several different mechanisms are capable of explaining the hydrolytic weakening effect, many have different dependencies upon the activity of oxygen so

  18. Microbiota of kefir grains

    OpenAIRE

    Tomislav Pogačić; Sanja Šinko; Šimun Zamberlin; Dubravka Samaržija

    2013-01-01

    Kefir grains represent the unique microbial community consisting of bacteria, yeasts, and sometimes filamentous moulds creating complex symbiotic community. The complexity of their physical and microbial structures is the reason that the kefir grains are still not unequivocally elucidated. Microbiota of kefir grains has been studied by many microbiological and molecular approaches. The development of metagenomics, based on the identification without cultivation, is opening new possibilities f...

  19. Grain Boundary Complexions

    Science.gov (United States)

    2014-05-01

    deter- mine bulk materials behavior and properties such as superplasticity, creep, fatigue, corrosion , strength and conductivity [2]. Grain boundary...interface (i.e. lattice mismatch accommodated by interface dislocations ), wetting transitions will not occur. A wetting transition is possible in the case...melting only starts around dislocations at low- angle grain boundaries; the grain boundary structure con- sists of isolated liquid pools separated by

  20. Compaction of cereal grain

    OpenAIRE

    Wychowaniec, J.; Griffiths, I.; Gay, A; Mughal, A.

    2013-01-01

    We report on simple shaking experiments to measure the compaction of a column of Firth oat grain. Such grains are elongated anisotropic particles with a bimodal polydispersity. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical shaking evolve to a dense state with evidence of nematic-like structure at the surface of the confining tube. This is accompanied by an increase in the packing fraction of the grain.

  1. Compaction of cereal grain

    Science.gov (United States)

    Wychowaniec, J.; Griffiths, I.; Gay, A.; Mughal, A.

    2013-11-01

    We report on simple shaking experiments to measure the compaction of a column of Firth oat grain. Such grains are elongated anisotropic particles with a bimodal polydispersity. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical shaking evolve to a dense state with evidence of nematic-like structure at the surface of the confining tube. This is accompanied by an increase in the packing fraction of the grain.

  2. Burial diagenetic processes of clay mineral and non-clay mineral, quartz cementation and dissolution in sandstones and mudstones of the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Svendsen, Johan Byskov

    grains (diatoms, radiolaria, sponge spicules), silica released from the hydration of volcanic glass, silica released detrital amorphous alumino-silicates that accumulated in muds, and decomposition of feldspars.  Silica release in shale does not necessarily source sandstone diagenesis but may...... of the biogenic silica has been transformed into opal-CT and partly to microcrystalline quartz.  The microcrystalline quartz is an internal sink for dissolved silica, but the shale may also have been an active silica exporter during this transition. With deeper burial (2000-2900m), opal-CT is fully transformed...... to microcrystalline quartz.  During this phase, silica has been partly mobile and depending on the rate of dissolution compared to the rate of precipitation, silica may have been lost to sandstone cementation.  Zeolite is also dissolved and mobilized silica may also have activated the shale as silica exporter...

  3. Gamma irradiation of quartz from Pannier basin, South America

    Energy Technology Data Exchange (ETDEWEB)

    Enokihara, Cyro T.; Rela, Paulo R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: cteiti@ipen.br, E-mail: prela@ipen.br; Guttler, Rainer A.S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias

    2007-07-01

    The use of gamma radiation to induce or enhance color centers in gemstones is a widespread technique and applied worldwide on a industrial scale since at least 1970. The presence of defects and defect structures in quartz from a border region of southern Brazil and Uruguay are the reason for the creation of a new color variety of quartz called 'Prasiolite' in the gem trade. This quartz has a pleasant green color produced by gamma irradiation. The procedures of irradiation at IPEN show that the activation of these color producing defects can be monitored by detailed chemical and spectroscopic analysis. For the first time UV-VIS-NIR spectra of this new color variety of quartz are shown. They revealed special features of these quartz crystals coming from basaltic terranes of the Parana Basin. Contrary to most specimen of quartz from other parts of Brazil, they have such a high water and OH content that they resemble more chalcedony or opal, but not highly crystalline quartz specimens. The cause of the color are broken bonds of Si-OH defining the so-called dangling bonds. (author)

  4. Relationship between amorphous silica and precious metal in quartz veins

    Science.gov (United States)

    Harrichhausen, N.; Rowe, C. D.; Board, W. S.; Greig, C. J.

    2015-12-01

    Super-saturation of silica is common in fault fluids, due to pressure changes associated with fracture, fault slip, or temperature gradients in hydrothermal systems. These mechanisms lead to precipitation of amorphous silica, which will recrystallize to quartz under typical geologic conditions. These conditions may also promote the saturation of precious metals, such as gold, and the precipitation of nanoparticles. Previous experiments show that charged nanoparticles of gold can attach to the surface of amorphous silica nanoparticles. Thus, gold and silica may be transported as a colloid influencing mineralization textures during amorphous silica recrystallization to quartz. This may enrich quartz vein hosted gold deposits, but the instability of hydrous silica during subsequent deformation means that the microstructural record of precipitation of gold is lost. We investigate a recent, shallow auriferous hydrothermal system at Dixie Valley, Nevada to reveal the nano- to micro-scale relationships between gold and silica in fresh veins. Fault slip surfaces at Dixie Valley exhibit layers of amorphous silica with partial recrystallization to quartz. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) show amorphous silica can contain a few wt. % gold while areas recrystallized to quartz are barren. At the Jurassic Brucejack deposit in British Columbia, Canada we observe the cryptocrystalline quartz textures that may indicate recrystallization from amorphous silica within quartz-carbonate veins containing high grade gold. Comb quartz within syntaxial veins, vugs, and coating breccia clasts indicate structural dilation. Vein geometry is investigated to determine relative importance of fault slip in creating dilational sites. By comparing quartz-carbonate veins from the Dixie Valley to Brucejack, we can determine whether amorphous silica formed in different environments show similar potential to affect precious metal mineralization.

  5. Proton induced defect formation in quartz glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gulamova, R.R.; Gasanov, E.M.; Alimov, R. [Uzbekian AS, Tashkent (Uzbekistan). Inst. of Nuclear Physics

    1996-12-31

    The contributions of ionization energy losses and elastic collisions to radiation induced defect formation along the proton track were considered in quartz glasses irradiated by protons with different energies. It is shown that on a larger part of the proton track the color and luminescence center formation by means of recharging of the native defects is due to the ionization energy losses. Generation of structural defects like displaced atoms and their vacancies by elastic collisions with protons and recoil atoms dominates for proton energies < 5 MeV. At proton energies > 10 MeV the color and luminescence center formation due to ionization energy losses prevails, and generation of the alumina-alkaline centers, causing an increase of the optical absorption at 550 nm and the thermoluminescence peak at 360 C and a band at 460 nm, occurs. At the proton energies E{sub p} < 10 MeV generation of the displaced atoms and their vacancies by elastic collisions dominates, leading to an increase of the E{prime}-centers and to the destruction and transformation of the alumina-alkaline centers.

  6. [Dermatologic risks of quartz-halogen lamps].

    Science.gov (United States)

    Cesarini, J P; Muel, B

    1992-01-01

    Halogene sources are used increasingly in general illumination. Their quartz envelop is technically necessary, but presents the disadvantage of to letting the emitted UVA, UVB and UVC go through. Originally used as in indirect lighting, they have been introduced as desk-top lamps, without filter. We have proceeded to the verification of their output with a spectrophotometer calibrated by actinometry and we have calculated their relative erythemal efficacy according to the Parrish's action spectrum for human erythema. We found that, at 10 cm from the human skin, the irradiance was able to induce a minimal erythema in about 10 minutes on clear back skin. At working distance (50 cm), a barely perceptible erythema could be observed on the back of the hands after 8 consecutive hours working. We also found that sunburn cells were present in the skin sensitized with a potent phototoxic agent (8-methoxypsoralen) applied 15 minutes before a 4-6 minutes irradiation with the halogen source (at 20 cm), thus, indicating a potential risk for local phototoxicity and photoallergy. The cumulative doses per year, for 4 hours exposure per day, five days a week, reaches 125 minimal erythemal doses, equivalent to the average yearly exposure of individuals for work and leisure. If one assumes that this regimen is maintained for 30 years, the risk for induction of skin cancers on the dorsal aspect of the hands and the forearms, may be increased by a 3.4 factor, according to the widely accepted previsional models.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Intracavity quartz-enhanced photoacoustic sensor

    Energy Technology Data Exchange (ETDEWEB)

    Borri, S., E-mail: simone.borri@ino.it; Galli, I.; Mazzotti, D.; Giusfredi, G.; De Natale, P. [CNR-INO UOS Sesto Fiorentino and LENS, via Carrara 1, 50019 Sesto Fiorentino FI (Italy); Patimisco, P.; Scamarcio, G.; Spagnolo, V. [CNR-IFN UOS Bari and Dipartimento Interateneo di Fisica, Università degli Studi di Bari e Politecnico di Bari, via Amendola 173, 70126 Bari BA (Italy); Akikusa, N. [Development Bureau Laser Device R and D Group, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan); Yamanishi, M. [Central Research Laboratories, Hamamatsu Photonics KK, Shizuoka 434-8601 (Japan)

    2014-03-03

    We report on a spectroscopic technique named intracavity quartz-enhanced photoacoustic spectroscopy (I-QEPAS) employed for sensitive trace-gas detection in the mid-infrared spectral region. It is based on a combination of QEPAS with a buildup optical cavity. The sensor includes a distributed feedback quantum cascade laser emitting at 4.33 μm. We achieved a laser optical power buildup factor of ∼500, which corresponds to an intracavity laser power of ∼0.75 W. CO{sub 2} has been selected as the target molecule for the I-QEPAS demonstration. We achieved a detection sensitivity of 300 parts per trillion for 4 s integration time, corresponding to a noise equivalent absorption coefficient of 1.4 × 10{sup −8} cm{sup −1} and a normalized noise-equivalent absorption of 3.2 × 10{sup −10} W cm{sup −1} Hz{sup −1/2}.

  8. Sorption of fluoride by quartz sand: batch tests

    Directory of Open Access Journals (Sweden)

    Eduardo Usunoff

    2009-06-01

    Full Text Available Despite the many efforts of scientists, in particular those from the field of soil science, the fate and distribution of fluorine (F species in soils and aquifers remain relatively unraveled. As for groundwater systems, such a shortcoming makes difficult the finding and development of safe water supplies. Likewise, the use of transport models does not render acceptable results because of the many uncertainties related to the behavior of F in aqueous media. This paper presents the results of four batch test in which solutions of different pH and [F-] (concentration of fluoride were in contact during 48 hours with clean quartz sand grains. The resulting data were fitted by linear versions of the Freundlich, the Langmuir, and the Langmuir-Freundlich models. The [F-] was varied between 0,5 and 10 mg L-1, except in one batch where a large initial concentration of F was used (45 mg L-1, and the range of pH used was 2,95 to 5,02. From a sieve analysis, the quartz grains had a medium size (d50 of 0,25 mm, and a uniformity coefficient (d40/d90 of 1,65. According to the fits and some dedicated goodness of fit indices, the Langmuir-Freundlich approach gave the best results for the batch test at the lowest pH, whereas the three remaining tests data were fitted by the Freundlich equation. It has to be mentioned that the pH of the equilibrium solutions were higher than the pH of the initial solutions, which was interpreted as an exchange process of OH- by F- on the quartz sand surface. However, such an exchange does not stand out as the exclusive mechanism promoting the F- disappearance from solution. It is deemed that the obtained results can be used as initial estimates of parameters in models used for calibrating the transport of F- in aquifers.A pesar de los muchos esfuerzos de los científicos, en particular de aquellos dedicados a las ciencias del suelo, el destino y la distribución de las especies de F (flúor en suelos y acuíferos continúan siendo

  9. Timescales recorded in volcanic quartz from Ti and Al diffusion profiles: a NanoSIMS investigation

    Science.gov (United States)

    Charlier, B. L.; Morgan, D. J.; Wilson, C. J.; Franchi, I. A.; Starkey, N. A.

    2012-12-01

    We have investigated the timescales of magma chamber assembly and recharge by applying diffusion modelling techniques to high resolution ion maps of titanium and aluminium in quartz produced by NanoSIMS analysis. The NanoSIMS is a multicollector instrument which is capable of detecting up to 7 different isotopes over a mass range up to a factor of 22 simultaneously, thus enabling the generation of compositional maps showing coupled spatial variations of multiple elements at a spot resolution down to ~150 nm. In this presentation, we demonstrate the utility of NanoSIMS for determining timescales from titanium and aluminium diffusion profiles across crystal interfaces within quartz grains with initially sharp Ti variations produced by multiple resorption episodes. Quartz crystals from the 25.4 ka ca. 530 cubic km Oruanui eruption (Taupo, New Zealand) were first imaged using CL to reveal complex zonation patterns reflecting several (up to 4) episodes of partial resorption and growth throughout the crystallisation history. Grains were then analysed for Ti and Al contents using conventional SIMS techniques (SHRIMP-RG) in order to characterise gross geochemical variations and to identify suitable areas for further analysis via the NanoSIMS. Selected 25 by 25 micron areas straddling dissolution boundaries were mapped to reveal measurable diffusion profiles. Those profiles in the interiors of grains occur over 6-8 microns and equate to hundreds of years of diffusive modification at plausible magmatic temperatures. Comparable timescales of hundreds of years are seen also in Fe-Mg diffusion profiles in orthopyroxenes from the Oruanui pumices and are interpreted to reflect extraction of melt and crystals from a mush source and assembly of the melt-dominant body (A.S.R. Allan et al.: From mush to eruption in 1000 years: rapid assembly of the super-sized Oruanui magma body. Abstract in Session V46). Ti profiles measured closer to the crystal rims occur over shorter length

  10. Single-grain results from an EMCCD-based imaging system

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Kook, Myung Ho; Murray, Andrew

    2015-01-01

    Here we compare the performance of an EMCCD-based imaging system with the standard laser-based single-grain Risø attachment. We first compare gamma dose distributions and the relative sensitivity of the two instruments is investigated using a single sample, by comparing the number of grains...... accepted into a dose distribution. EMCCD cross-talk is shown to be of concern at low light levels.We also make use of the fact that the EMCCD can observe TL signals from individual grains to examine the use of the correlation between the quartz 110 C TL peak and the fast component OSL signal to correct...

  11. Anisotropic annealing of fission fragments in synthetic quartz

    CERN Document Server

    Sawamura, T; Narita, M

    1999-01-01

    A study on the thermal annealing behavior of fission fragments in synthetic quartz crystals was performed for application of synthetic quartz to track detectors under high temperature circumstances: x-, y-, and z-cut quartz plates were exposed to fission fragments from sup 2 sup 5 sup 2 Cf and were annealed up to 750 deg. C. It was found that track retention depended on the crystallographic structure: the annealing temperature, where the number of etched tracks was sharply reduced, was 550 deg. C for the x- and y-cut plates and 750 deg. C for z-cut plates. Track sizes decrease and disperse with reductions in the track retention.

  12. Retention of xenon in quartz and Earth's missing xenon.

    Science.gov (United States)

    Sanloup, Chrystèle; Schmidt, Burkhard C; Chamorro Perez, Eva Maria; Jambon, Albert; Gregoryanz, Eugene; Mezouar, Mohamed

    2005-11-18

    The reactivity of xenon with terrestrial oxides was investigated by in situ synchrotron x-ray diffraction. At high temperature (T > 500 kelvin), some silicon was reduced, and the pressure stability of quartz was expanded, attesting to the substitution of some xenon for silicon. When the quartz was quenched, xenon diffused out and only a few weight percent remained trapped in samples. These results show that xenon can be covalently bonded to oxygen in quartz in the lower continental crust, providing an answer to the missing xenon problem; synthesis paths of rare gas compounds are also opened.

  13. Recent developments of OSL techniques for dating quartz and feldspars

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Jungner, H.; Mejdahl, V.

    1993-01-01

    The construction of a unit for measuring optically stimulated luminescence from quartz and feldspar is described. The light sources used for stimulation are infrared diodes for feldspar and green light from a halogen lamp (obtained with a system of filters) for both quartz and feldspar. The unit...... can be mounted on the Riso TL reader thus allowing combined TL and OSL measurements. The apparatus was used for studies of (1) the relation between TL and OSL signals, (2) the luminescence of quartz samples annealed at different temperatures and (3) anomalous fading of the latent luminescence signal...

  14. Using a titanium-in-quartz geothermometer for crystallization temperature estimation of the Palaeoproterozoic Suursaari quartz porphyry

    Directory of Open Access Journals (Sweden)

    Kairi Ehrlich

    2012-11-01

    Full Text Available The Suursaari volcanic sequence represents volcanic activity related to Wiborg Batholith rapakivi intrusions in the southern part of the Fennoscandian Shield. The estimated pressure conditions for batholith granitic rocks are 1–5 kbar and crystallization temperatures range from 670 to 890 °C. To describe the temperature regime of the Suursaari volcanic system, a rock sample was taken from the Mäkiinpäällys Mountain outcrop and analysed with laser ablation inductively coupled plasma mass spectrometry. Sample spots were selected from quartz phenocrysts and groundmass. Quartz crystallization temperatures were calculated by the Ti-in-quartz method that takes into account rutile equilibrium and Ti activity in each phase. The calculated crystallization temperatures of the Suursaari quartz porphyry are in the range of 647–738 °C. The results show that the Suursaari quartz porphyry contains two generations of quartz which can be distinguished on the basis of crystallization temperatures: phenocrysts crystallized at higher and groundmass quartz at lower temperature.

  15. Transport of Escherichia coli in 25 m quartz sand columns.

    Science.gov (United States)

    Lutterodt, G; Foppen, J W A; Maksoud, A; Uhlenbrook, S

    2011-01-25

    To help improve the prediction of bacteria travel distances in aquifers laboratory experiments were conducted to measure the distant dependent sticking efficiencies of two low attaching Escherichia coli strains (UCFL-94 and UCFL-131). The experimental set up consisted of a 25 m long helical column with a diameter of 3.2 cm packed with 99.1% pure-quartz sand saturated with a solution of magnesium sulfate and calcium chloride. Bacteria mass breakthrough at sampling distances ranging from 6 to 25.65 m were observed to quantify bacteria attachment over total transport distances (α(L)) and sticking efficiencies at large intra-column segments (α(i)) (>5m). Fractions of cells retained (F(i)) in a column segment as a function of α(i) were fitted with a power-law distribution from which the minimum sticking efficiency defined as the sticking efficiency of 0.001% bacteria fraction of the total input mass retained that results in a 5 log removal were extrapolated. Low values of α(L) in the order 10(-4) and 10(-3) were obtained for UCFL-94 and UCFL-131 respectively, while α(i)-values ranged between 10(-6) to 10(-3) for UCFL-94 and 10(-5) to 10(-4) for UCFL-131. In addition, both α(L) and α(i) reduced with increasing transport distance, and high coefficients of determination (0.99) were obtained for power-law distributions ofα(i) for the two strains. Minimum sticking efficiencies extrapolated were 10(-7) and 10(-8) for UCFL-94 and UCFL-131, respectively. Fractions of cells exiting the column were 0.19 and 0.87 for UCFL-94 and UCL-131, respectively. We concluded that environmentally realistic sticking efficiency values in the order of 10(-4) and 10(-3) and much lower sticking efficiencies in the order 10(-5) are measurable in the laboratory, Also power-law distributions in sticking efficiencies commonly observed for limited intra-column distances (6m) in columns packed with quartz grains. High fractions of bacteria populations may possess the so-called minimum sticking

  16. Correlation Between Grain Size Distribution and Silicon and Oxygen Contents at Wadi Arar Sediments, Kingdom of Saudi Arabia

    OpenAIRE

    Alghamdi, M. A. M.

    2017-01-01

    Quartz is the major mineral of Wadi Arar sediments. The top two elements contents are oxygen with 63.96 wt%, followed by silicon with 16.35 wt%. There is a positive, weak to medium correlation between grain size and silicon and oxygen contents. The correlation between oxygen and grain size is four times higher than that of silicon. At grain size ranges between 0.8 and 1.0 mm, both oxygen and silicon show the maximum correlation, which decrease gradually with finer and coarser grain sizes. For...

  17. Influence of humic acid concentration on nTiO2 attachment to quartz sand and Fe-coated quartz sand

    Science.gov (United States)

    Cheng, T.; Wu, Y.

    2016-12-01

    The transport of nano-scale or micro-scale titanium dioxide particles (nTiO2) in subsurface environments are strongly influenced by nTiO2 attachment to sediment grains. The objective of this study is to investigate the role of humic acid (HA) in the attachment of nTiO2 to sand at low HA concentrations that are relevant to typical groundwater conditions, so that mechanisms that control nTiO2 immobilization and transport in groundwater can be elucidated. nTiO2 may carry either positive or negative charges in natural water, therefore, environmental factors such as pH, humic substances, and Fe oxyhydroxide coatings on sediment grains, which are known to control the transport of negatively-charged colloids, may influence nTiO2 in different manners. Attachment of nTiO2 to quartz sand and Fe oxyhydroxide coated quartz sand are experimentally measured under a range of HA concentrations at fixed pH. Experimental results show that at pH 5, negatively-charged HA strongly adsorbs to positively-charged nTiO2 and Fe oxyhydroxide, which, at low HA concentrations, partially neutralizes the positive charges on nTiO2 and Fe oxyhydroxide, and therefore decreases the repulsive electrostatic forces between the surfaces, resulting in relatively high nTiO2 attachment. At high HA concentrations, adsorbed HA reverses the surface charges of nTiO2 and Fe oxyhydroxide, and makes nTiO2 and Fe oxyhydroxide strongly negatively charged, resulting in low nTiO2 attachment. At pH 9, HA, nTiO2, and Fe oxyhydroxide are all negatively charged, and HA adsorption is low and does not have a strong impact on the attachment of nTiO2. This study demonstrates that the changes in surface charges of nTiO2 and Fe oxyhydroxide coating caused by HA adsorption could be a key factor that controls the attachment of nTiO2 to sediment grains.

  18. Optically stimulated luminescence and isothermal thermoluminescence dating of high sensitivity and well bleached quartz from Brazilian sediments: from Late Holocene to beyond the Quaternary?

    Directory of Open Access Journals (Sweden)

    André Oliveira Sawakuchi

    Full Text Available ABSTRACT: The development of optically stimulated luminescence (OSL dating of sediments has led to considerable advance in the geochronology of the Quaternary. OSL dating is a well established technique to determine sediment burial ages from tens of years to few hundred thousand years. Recent studies have shown that Quaternary sediments of Brazil are dominated by quartz grains with high luminescence sensitivity, allowing the determination of precise and reliable OSL burial ages. In this paper, we show examples of OSL dating of quartz aliquots and single grains from different regions in Brazil, including young coastal-eolian Late Holocene ( 2 Ma in the low dose rate (0.5 - 1.0 Gy/ka environments typical for Brazilian sediments.

  19. The origin of the medium OSL component in West Australian quartz

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.L., E-mail: wxl@loess.llqg.ac.cn [SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075 (China); Key Laboratory of Western Mineral Resources and Geological Engineering, Ministry of Education of China and Chang’an University, Xi’an 710054, Shaanxi (China); Du, J.H. [SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075 (China); Key Laboratory of Western Mineral Resources and Geological Engineering, Ministry of Education of China and Chang’an University, Xi’an 710054, Shaanxi (China); Adamiec, G. [Silesian University of Technology, Institute of Physics—Centre for Science and Education, ul. Konarskiego 22B, 44-100 Gliwice (Poland); Wintle, A.G. [Institute of Geography and Earth Sciences, Aberystwyth University, Aberystwyth SY23 3DB (United Kingdom); McDonald Institute for Archaeological Research, University of Cambridge, Downing Street, Cambridge CB2 3ER (United Kingdom)

    2015-03-15

    Optically stimulated luminescence (OSL) of a coarse-grained sedimentary quartz from West Australia was investigated. Observations of OSL and TL (thermoluminescence) were made following a series of experiments using different heating and optical bleaching conditions, and with optical stimulation at several different temperatures. Analysis of the fast and medium OSL components suggests that the medium OSL component observed after heating at 260 °C is a by-product of the production of the fast component, and both of them have as their original source the 325 °C TL trap. During fast OSL production following irradiation and preheating, some of the electrons evicted into the conduction band are re-trapped in an intermediate trap corresponding to the 170 °C TL peak; from here they are instantaneously stimulated to give rise to the medium OSL signal when the blue light stimulation is switched on, and subsequently result in the residual recuperated TL after the blue light is switched off. The kinetic properties of the medium OSL component are determined by the properties of both the 170 °C and 325 °C TL traps in contrast to the conventional interpretation of the medium component being derived from an independent source trap. Therefore, the 170 °C TL trap also plays unexpected roles in quartz OSL production with elevated stimulation temperatures (e.g. 125 °C or 130 °C, currently used for OSL dating), while the 110 °C TL trap and its influences are being avoided. - Highlights: • Quartz medium OSL component is a by-product of fast OSL component production. • Medium component is mediated by the 170 C TL peak. • Phototransfer is responsible for the medium OSL.

  20. Towards understanding inter-strain attachment variations of Escherichia coli during transport in saturated quartz sand.

    Science.gov (United States)

    Foppen, Jan Willem; Lutterodt, George; Röling, Wilfred F M; Uhlenbrook, Stefan

    2010-02-01

    Although Escherichia coli is an indicator of fecal contamination in aquifers, limited research has been devoted to understanding the biological processes involved in the initial attachment of E. coli transported in abiotic porous media. The roles of the various surface structures of E. coli, like lipopolysaccharides (LPS), autotransporter proteins, and fimbriae are unknown. The objective of this research was to establish the effects of variations in surface characteristics of the outer membrane of E. coli on the attachment efficiency of 54 E. coli strains upon transport in saturated quartz sand under identical flow conditions. We used column experiments to assess retention of the E. coli strains, and we determined sphericity, motility, zeta-potential, and aggregation of all strains. LPS composition was determined based on known serotypes, and the presence/absence of 22 genes encoding surface characteristics was determined with qualitative PCR. The results indicated that under identical flow conditions, there was a variation of two orders of magnitude in the maximum breakthrough concentrations of the 54 E. coli strains. Of all factors we investigated, no single factor was able to explain attachment efficiency variations statistically significantly. However, low attachment efficiencies were associated (p=0.13) with LPS containing saccharides with phosphate and/or carboxyl groups. These saccharide groups are acidic and likely charged with a negative O-atom, which reduced attachment to the negatively charged quartz surface. In addition, of the 22 genes tested, Afa was most associated (p=0.21) with attachment efficiency. The work presented here bridges knowledge on colloid transport and molecular microbiology, and tries to offer a more holistic view on the attachment of planktonic E. coli bacteria to (abiotic) quartz grain surfaces. Future research should involve the use of microbiological techniques in order to be able to map the unique or grouped characteristics of E

  1. Structure optimization and simulation analysis of the quartz micromachined gyroscope

    Directory of Open Access Journals (Sweden)

    Xuezhong Wu

    2014-02-01

    Full Text Available Structure optimization and simulation analysis of the quartz micromachined gyroscope are reported in this paper. The relationships between the structure parameters and the frequencies of work mode were analysed by finite element analysis. The structure parameters of the quartz micromachined gyroscope were optimized to reduce the difference between the frequencies of the drive mode and the sense mode. The simulation results were proved by testing the prototype gyroscope, which was fabricated by micro-electromechanical systems (MEMS technology. Therefore, the frequencies of the drive mode and the sense mode can match each other by the structure optimization and simulation analysis of the quartz micromachined gyroscope, which is helpful in the design of the high sensitivity quartz micromachined gyroscope.

  2. Miniature Quartz Crystal Microbalance for Spacecraft and Missile Applications

    National Research Council Canada - National Science Library

    Uy, O

    1999-01-01

    Quartz crystal microbalances (QCMs) have been used for over 20 years as contamination monitors in spacecraft to measure film deposition on sensitive surfaces such as optical mirrors, thermal radiators, and solar arrays...

  3. Degradation of glycine and alanine on irradiated quartz.

    Science.gov (United States)

    Pawlikowski, Maciej; Benko, Aleksandra; Wróbel, Tomasz P

    2013-04-01

    Recent researches suggest participation of minerals in the formation of life under primordial conditions. Among all of the minerals, quartz seems to be one of the most probable to take part in such processes. However, an external source of energy is needed, e.g. electric discharge. A device simulating the proposed conditions was designed and was used to simulate prebiotic conditions. Investigation of processes occurring during the stimulation of quartz with electric discharge was studied by means of Ultraviolet-visible (UV-VIS) spectroscopy, in order to monitor the generation kinetics of free radicals. Additionally, infrared spectroscopy was applied to identify chemical reaction products created in a solution of alanine or glycine, in the presence of quartz treated with electric discharge. Formation of increased amounts of free radicals, compared to experiments performed without quartz and/or amino acid, is reported, along with identification of possible degradation products of alanine. No synthetic reactions were observed.

  4. Petrographic and optical cathodoluminescence study of detrital quartz

    African Journals Online (AJOL)

    Basange Formation had been investigated using integrated optical Cathodoluminescence and Petrographic characteristics approach. Results showed the presence, in abundance, of detrital quartz with characteristic dull red to violet CL colour and ...

  5. Diagenetic quartz and amorphous silica in New Zealand coals

    Energy Technology Data Exchange (ETDEWEB)

    Sykes, R.; Lindqvist, J.K. (Institute of Geological and Nuclear Sciences, Dunedin (New Zealand))

    1993-08-01

    New Zealand coal seams (Late Cretaceous-Miocene, lignite-semi-anthracite) contain numerous and varied occurrences of diagenetic quartz and amorphous silica. Early diagenetic silicifications include: sub-horizontal and laterally extensive, quartz-mineralized bands; micro- and megascopic, euhedral quartz crystals, dispersed or concentrated in layers; and silicified in situ tree stumps. Late diagenetic forms include: sub-horizontal, quartz-mineralized bands, mostly [lt] 1 m in length; and fracture-infillings. The origins of the silica remain uncertain but leached basement rocks and coal measure sediments, and siliceous phytoliths within the coal-forming plants, are possible sources. The silicification of coal seams may have significant implications for exploration, mining and geological studies. 39 refs., 5 figs., 4 plates.

  6. In-homogeneity in the pre-dose sensitization of the 110 Degree-Sign C TL peak in various quartz samples: The influence of annealing

    Energy Technology Data Exchange (ETDEWEB)

    Polymeris, George S., E-mail: polymers@auth.gr [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); ISIK University, Faculty of Science and Arts, Physics Department, Sile 34980, Istanbul (Turkey); Oniya, Ebenezer O. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); Physics and Electronics Department, Adekunle Ajasin University, PMB 01 Akungba Akoko (Nigeria); Jibiri, Nnamdi N. [Department of Physics, University of Ibadan, Ibadan (Nigeria); Tsirliganis, Nestor C. [Laboratory of Radiation Applications and Archaeological Dating, Department of Archaeometry and Physicochemical Measurements, Cultural and Educational Technology Institute, Athena, Research and Innovation Center in Information, Communication and Knowledge Technologies, Tsimiski 58, GR-67100 Xanthi (Greece); Kitis, George [Aristotle University of Thessaloniki, Nuclear Physics Laboratory, 54124 Thessaloniki (Greece)

    2012-03-01

    The pre-dose sensitization effect of the 110 Degree-Sign C TL glow-peak of quartz is a basic tool in thermoluminescence and optically stimulated luminescence dating and retrospective dosimetry. In the present work, a homogeneity study was performed on pre-dose sensitization in grains obtained from large quartz crystals samples collected from 10 different origins. The aliquot - to - aliquot scatter of the pre-dose sensitization of the 110 Degree-Sign C TL peak within each quartz crystal was monitored. The influence of the annealing on this scattering was also studied. Therefore, the investigation was applied to the un-fired 'as is' samples as well as to samples annealed at 900 Degree-Sign C for 1 h following cooling to room temperature in air. The results showed that in the case of 'as is' quartz the sensitization effect vary strongly within each aliquot of the same quartz sample. This strong variation is removed by both the high temperature annealing as well as heating up to 500 Degree-Sign C, involved in the TL measurements. These results are generally discussed in the framework of existing models and applications of the effect.

  7. Influence of quartz particles on wear in vertical roller mills

    DEFF Research Database (Denmark)

    Jensen, Lucas R.D.; Friis, Henrik; Fundal, Erling

    2010-01-01

    statistical planning, a total of 10 tests were arried out with two different limestones and one type of quartz sand. The size distributions were kept constant and only the mixing ratios were varied. It appears from the investigation that mixtures consisting of minerals with different grindabilities result...... in an increased concentration of abrasive particles in the grinding bed ðR2 > 0:99Þ. The present study shows that the quartz concentration in the grinding bed is determining the wear rate....

  8. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy

    OpenAIRE

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S.; Beere, Harvey E.; Ritchie, David A.; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

    2016-01-01

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH3OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a ...

  9. The range of dynamic recrystallization of quartz - An updated correlation between nature and experiment

    Science.gov (United States)

    Stipp, Michael

    2014-05-01

    Several microstructural correlations between natural and experimental conditions for dynamic recrystallization of quartz have been proposed (e.g., Hirth et al. 2001; Stipp et al. 2002), but an attempt to unify the different results and data sets is missing. Based on additional experiments and a statistical analysis of microstructural data (e.g., Stipp et al. 2006, 2010) four characteristic microstructural zones with corresponding recrystallized grain size (D) ranges can be identified. (I) D migration and subgrain rotation contribute to recrystallization, and that grain boundary sliding may operate at high strain (Stipp and Kunze, 2008). Comparable microstructures have not been observed in natural shear zones; their formation is not possible at greenschist facies conditions, because the required differential stresses would be larger than the confining pressure and so in conflict with the Goetze criterion (Kohlstedt et al. 1995). (II) D ˜3-35 µm: Experimental dislocation creep regimes 2 and 3 (Hirth and Tullis 1992), corresponding to the natural BLG zone of Stipp et al. (2002). Microstructures are again characterized by porphyroclasts with grain boundary bulges and small recrystallized grains. Compared to zone I, less strain is required to produce a considerable amount of recrystallized grains, forming "core-mantle microstuctures". (III) D ˜35-120 µm: Upper experimental dislocation creep regime 3, and natural SGR zone (Stipp et al. 2006, 2010). Microstructures are characterized by porphyroclastic ribbon grains and recrystallized grains which are about the same size or slightly larger than optical subgrains. Subgrain formation and dynamic recrystallization are initiated at low strain yielding "polygonization microstructures". (IV) D > 120 µm: The natural GBM zone (Stipp et al. 2002). Comparable microstructures have not been attained in experimentally deformed samples, because the required high temperatures and/or water contents cause partial melting

  10. Effect of particle size in the TL response of natural quartz sensitized with high gamma dose

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, A B Jr; Guzzo, P L; Sullasi, H L; Khoury, H J, E-mail: alvarobcjr@yahoo.com.b

    2010-11-01

    The aim of this study is to investigate the effect of particle size in the thermoluminescence (TL) response of natural quartz sensitized with high gamma dose. For this, fragments of a single crystal taken from the Solonopole district (Brazil) were crushed and classified into ten size fractions ranging from 38 {mu}m to 5 mm. Aliquots of each size fraction were sensitized with 25 kGy of gamma dose of {sup 60}Co and heat-treated in a muffle furnace at 400{sup o}C. The non-sensitized samples were exposed to test doses between 50 Gy and 5 kGy and the sensitized samples were exposed to a unique test dose equal to 50 mGy. For non-sensitized samples, the TL peak near 325 {sup 0}C increases with the particle size decreasing. However, in the case of sensitized samples, the TL output near 280 {sup 0}C increases with the increasing of particle size up to mean grain size equal to 308 {mu}m. Above 308 {mu}m, an abrupt reduction in the TL intensity was noticed. These effects are discussed in relation to the specific surface area and the different interaction of high gamma doses with fine and coarse particles of quartz.

  11. Experimental hypervelocity impact into quartz sand - Distribution and shock metamorphism of ejecta

    Science.gov (United States)

    Stoeffler, D.; Gault, D. E.; Wedekind, J.; Polkowski, G.

    1975-01-01

    Results are presented for vertical impacts of 0.3-g cylindrical plastic projectiles into noncohesive quartz sand in which vertical and horizontal reference strate were employed by using layers of colored sand. The impacts were performed at velocities of 5.9-6.9 km/sec with a vertical gun ballistic range. The craters, 30-33 cm in diameter, reveal a radial decay of the ejecta mass per unit area with a power of -2.8 to -3.5. Material displaced from the upper 15% of the crater depth d is represented within the whole ejecta blanked, material from deeper than 28% of d is deposited inside 2 crater radii, and no material from deeper than 33% of d was ejected beyond the crater rim. Shock-metamorphosed particles (glassy agglutinates, cataclastic breccias, and comminuted quartz) amount to some 4% of the total displaced mass and indicate progressive zones of decay of shock intensity from a peak pressure of 300 kbar. The shock-metamorphosed particles and the shock-induced change in the grain size distribution of ejected samples have close analogies to the basic characteristics of the lunar regolith. Possible applications to regolith formation and to ejecta formations of large-scale impact craters are discussed.

  12. New observations on the quartz monzodiorite-granite suite. [in lunar soil

    Science.gov (United States)

    Marvin, U. B.; Holmberg, B. B.; Lindstrom, M. M.; Martinez, R. R.

    1991-01-01

    Five new fragments of quartz monzodiorite (QMD) were identified in particles from soil 15403, which was collected from the boulder sampled as rock 15405, an impact-melt breccia containing clasts of KREEP basalt, QMD, granite, and a more primitive alkali norite. Petrographic and geochemical studies of the fragments show considerable variation in modal proportions and bulk composition. This heterogeneity is due to unrepresentative sampling in small fragments of coarse-grained rocks. Variations in the proportions of accessory minerals have marked effects on incompatible-trace-element concentrations and ratios. Semiquantitative calculations support the derivation of QMD from 60-percent fractional crystallization of a KREEP basalt magma as suggested by Hess (1989). Apollo 15 KREEP basalt cannot be the actual parent magma because the evolved rocks predate volcanic KREEP basalts. It is suggested that ancient KREEP basalt magmas have crystallized as plutons, with alkali norite clasts offering the only direct evidence of this precursor.

  13. Direct growth of graphene on quartz substrates for label-free detection of adenosine triphosphate.

    Science.gov (United States)

    Xu, Shicai; Man, Baoyuan; Jiang, Shouzhen; Yue, Weiwei; Yang, Cheng; Liu, Mei; Chen, Chuansong; Zhang, Chao

    2014-04-25

    We demonstrate that continuous, uniform graphene films can be directly synthesized on quartz substrates using a two-temperature-zone chemical vapor deposition system and that their layers can be controlled by adjusting the precursor partial pressure. Raman spectroscopy and transmission electron microscopy confirm the formation of monolayer graphene with a grain size of ∼100 nm. Hall measurements show a room-temperature carrier mobility above 1500 cm2 V(-1) s(-1). The optical transmittance and conductance of the graphene films are comparable to those of transferred metal-catalyzed graphene. The method avoids the complicated and skilled post-growth transfer process and allows the graphene to be directly incorporated into a fully functional biosensor for label-free detection of adenosine triphosphate (ATP). This device shows a fast response time of a few milliseconds and achieves a high sensitivity to ATP molecules over a very wide range from 0.002 to 5 mM.

  14. Preliminary report on radiation-induced thermoluminescence in Climax Stock quartz monzonite

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R.; Page, L.; Koons, L.; Sundbeck, C.

    1981-11-01

    An examination has been made of the feasibility of using thermoluminescence (TL) for the self-dosimetry of the rock surrounding a canister of nuclear waste. The rock investigated was quartz monzonite from the Climax Stock, a granite intrusive at the Nevada Test Site. Samples of the rock were irradiated by {sup 60}Co to doses of 10{sup 3} to 10{sup 9} rads, then ground to a fine powder and read for TL response at a heating rate of 1{sup 0}C per second. Effects of total dose, thermal history after irradiation, grinding to a powder after irradiation, mineral composition, and powder grain size were investigated. All were found to be important, but with care, the use of TL in this manner appears promising.

  15. Basic characteristics of quartz crystal sensor with interdigitated electrodes

    Directory of Open Access Journals (Sweden)

    Hiroshi Muramatsu

    2016-03-01

    Full Text Available This paper describes basic characteristics of the quartz crystal sensor with interdigitated electrodes (IDE quartz crystal sensor which is for simultaneous monitoring of mass, viscosity, conductivity and dielectric changes of liquids or thin films. As the IDE quartz crystal sensor has three terminals for a pair of IDEs on the one side and a counter electrode on the other side, the resonance properties have been analyzed using the electrical equivalent circuit models and measured experimentally for all connecting types of electrode pairs. The IDE quartz crystal has shown clear resonance curves for calculating the resonance frequency and resonance resistance values as well as normal quartz crystal in the air and in contact with liquid. Small shifts in the resonance frequency and resonance resistance depending on the connecting types have been obtained and analyzed using the equivalent circuit models. We have found the integrated quartz crystal and IDE sensors could be monitored simultaneously by only one impedance analyzer. Finally, two types of measuring systems have been demonstrated for continuous measuring methods.

  16. Interaction Between Graphene Oxide Nanoparticles and Quartz Sand.

    Science.gov (United States)

    Sotirelis, Nikolaos P; Chrysikopoulos, Constantinos V

    2015-11-17

    In this study, the influence of pH, ionic strength (IS), and temperature on graphene oxide (GO) nanoparticles attachment onto quartz sand were investigated. Batch experiments were conducted at three controlled temperatures (4, 12, and 25 °C) in solutions with different pH values (pH 4, 7, and 10), and ionic strengths (IS = 1.4, 6.4, and 21.4 mM), under static and dynamic conditions. The surface properties of GO nanoparticles and quartz sand were evaluated by electrophoretic mobility measurements. Derjaguin-Landau-Verwey-Overbeek (DLVO) potential energy profiles were constructed for the experimental conditions, using measured zeta potentials. The experimental results showed that GO nanoparticles were very stable under the experimental conditions. Both temperature and pH did not play a significant role in the attachment of GO nanoparticles onto quartz sand. In contrast, IS was shown to influence attachment. The attachment of GO particles onto quartz sand increased significantly with increasing IS. The experimental data were fitted nicely with a Freundlich isotherm, and the attachment kinetics were satisfactorily described with a pseudo-second-order model, which implies that the quartz sand exhibited substantial surface heterogeneity and that GO retention was governed by chemisorption. Furthermore, thermodynamic analysis revealed that the attachment process was nonspontaneous and endothermic, which may be associated with structural changes of the sand surfaces due to chemisorption. Therefore, secondary minimum interaction may not be the dominant mechanism for GO attachment onto the quartz sand under the experimental conditions.

  17. New approaches in luminescence dating using single grains of small and large sizes

    Science.gov (United States)

    Chauhan, N.; Shinde, D. P.; Anand, S.; Mayya, Y. S.; Singhvi, A. K.

    2009-04-01

    Luminescence dating of sediments relies on the estimation of the dose absorbed by a constituent mineral grain (quartz and/or feldspar) from the natural radiation field arising from the decay of natural radioactivity viz. U, Th and K. A minor contribution is provided by the cosmic rays. Improvements in measurement technology have enabled the measurements of single grains. Using Monte Carlo simulations we explore here the implications of two realms of single grains, one where the size of grains is larger or comparable to the beta ranges (centimeter to sub centimeter scale) and the other when the size is much smaller (micrometer to sub millimeter scale), In the case of large grain sizes, we suggest that the beta dose to the grains get attenuated with depth such that the interior of the grains receives only a fraction of total dose, mostly due to the gamma rays. This fraction is typically ~30% of the total dose. Under the same irradiation condition, such a truncated dose rate implies a delayed onset of saturation in the growth of luminescence signal with radiation does. This implies an increased dating range. Based on a detailed calculation of the dose-depth profiles, we present a conceptual frame work for a three to four fold increase in the age range achievable by conventional dating protocols using 100-200 m grains. This is based on removal of the beta skin of a large grain akin to the removal of the alpha skin in the case of small grains. Experiments on the optical transparency of large grains suggested a finite light transmission through 7 mm thick slices of quartz. This ensures that despite the size the geological luminescence of the grains will get photobleached, providing a way for their application in dating. Given that the beta dose attenuation is dependent on the grain size, it is reasonable to expect that the total absorbed dose is also grain size dependent. This implies the prospects of development of an isochronal methods, where the absorbed doses are

  18. A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications

    National Research Council Canada - National Science Library

    Tomasz Starecki; Piotr Z Wieczorek

    2017-01-01

    All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations...

  19. Sedimentary controls on modern sand grain coat formation

    Science.gov (United States)

    Dowey, Patrick J.; Worden, Richard H.; Utley, James; Hodgson, David M.

    2017-05-01

    Coated sand grains can influence reservoir quality evolution during sandstone diagenesis. Porosity can be reduced and fluid flow restricted where grain coats encroach into pore space. Conversely pore-lining grain coats can restrict the growth of pore-filling quartz cement in deeply buried sandstones, and thus can result in unusually high porosity in deeply buried sandstones. Being able to predict the distribution of coated sand grains within petroleum reservoirs is thus important to help find good reservoir quality. Here we report a modern analogue study of 12 sediment cores from the Anllóns Estuary, Galicia, NW Spain, collected from a range of sub-environments, to help develop an understanding of the occurrence and distribution of coated grains. The cores were described for grain size, bioturbation and sedimentary structures, and then sub-sampled for electron and light microscopy, laser granulometry, and X-ray diffraction analysis. The Anllóns Estuary is sand-dominated with intertidal sand flats and saltmarsh environments at the margins; there is a shallowing/fining-upwards trend in the estuary-fill succession. Grain coats are present in nearly every sample analysed; they are between 1 μm and 100 μm thick and typically lack internal organisation. The extent of grain coat coverage can exceed 25% in some samples with coverage highest in the top 20 cm of cores. Samples from muddy intertidal flat and the muddy saltmarsh environments, close to the margins of the estuary, have the highest coat coverage (mean coat coverage of 20.2% and 21.3%, respectively). The lowest mean coat coverage occurs in the sandy saltmarsh (10.4%), beyond the upper tidal limit and sandy intertidal flat environments (8.4%), close to the main estuary channel. Mean coat coverage correlates with the concentration of clay fraction. The primary controls on the distribution of fine-grained sediment, and therefore grain coat distribution, are primary sediment transport and deposition processes that

  20. Grain boundaries: Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1988-02-01

    Quantitative measurements of grain boundary structure factors using x-ray diffraction have been performed on low angle (001) twist boundaries in gold. Also, a computer atomistic simulation program is being implemented to examine the equilibrium properties of a series of boundaries in gold. Simulation of boundaries at room temperature have been performed. Electron microscopy of grain boundary melting in aluminum was also performed. Results indicated an absence of melting. (CBS)

  1. Relating titanium distribution and stable isotope thermometry to quartz microstructure in an extensional detachment system, Shuswap metamorphic core complex, British Columbia

    Science.gov (United States)

    Nachlas, W. O.; Seaton, N. C.; Whitney, D. L.; Teyssier, C.; Mulch, A.; Grove, M.

    2010-12-01

    Microstructural and textural observations in deformed rocks can be used to interpret the thermal history and rheological behavior of extensional shear zones. The interaction between deformation and dynamic recrystallization of individual mineral phases controls the preserved microstructures and provides insight into the physical and chemical response to plastic deformation. The accommodation of internal strain within a deformed mineral through the migration of lattice dislocations produces textural features that are indicative of deformation conditions. Mechanisms of dislocation creep are intimately linked to the mobility and distribution of trace elements within a dynamically recrystallized grain and can be used to interpret the temperature conditions of deformation. The Shuswap metamorphic core complex is a migmatite-cored gneiss dome situated within the Omineca crystalline belt of southern British Columbia. Exhumation of the dome was accommodated by a brittle-ductile detachment system localized within a thick (~800 m) sequence of quartzite mylonite. The quartzite is characterized by large elongate quartz ribbons locally mantled by recrystallized subgrains which preserve similar grain size between the three samples of interest. Detailed crystallographic preferred orientation measurements (EBSD) coupled with high resolution ion microprobe (SHRIMP-RG) analysis of quartz provides insight into the thermal evolution of quartz microstructure. Titanium concentration varies systematically both within single grains and between different structural levels in the detachment. Within the samples analyzed, a pattern of decreasing Ti content from core to recrystallized rim remains consistent regardless of the absolute concentration. The Ti values vary as follows, core/rim: 7-9.5 ppm/4.5-6.5 ppm; 11-14 ppm/7.5-10 ppm; 17-20 ppm/13-16 ppm. Intra-grain Ti content varies systematically with cathodoluminescence intensity and can be used to thermally track dynamic recrystallization

  2. Quartz concentration trends in metal and nonmetal mining.

    Science.gov (United States)

    Watts, Winthrop F; Huynh, Tran B; Ramachandran, Gurumurthy

    2012-01-01

    From 1974 through 2010, the Mine Safety and Health Administration (MSHA) collected nearly 147,000 respirable dust samples with a mass of at least 0.1 mg and a minimum of 1% quartz. These samples represent about 50% of all respirable dust compliance samples collected by MSHA. Analysis of these data shows that pockets of high concentrations and overexposure continue to exist. At underground mines, from 2005 to 2010, occupations with >20% of the samples exceeding the permissible exposure limit (PEL) and geometric mean quartz concentrations exceeding the ACGIH threshold limit value of 25 μg/m(3) included mucking, crusher operator, general laborer/utility, and front-end loader operator. During the same period, stone and rock saw operators and bagger and packers working at surface mines and mills also had >20% of the samples exceeding the PEL and geometric mean quartz concentrations >25 μg/m(3). Regardless of mine type or location, slow but steady improvement in exposure levels is seen in jobs involving crushing operations, which are widespread in the mining industry. Crusher operators are more likely to work in an enclosed area where it is easier to apply dust controls and air conditioning. A downward trend is also observed for vehicle equipment operators who drive load-haul-dumps, front-end loaders, trucks, and similar equipment. Crusher operators and vehicle equipment operators represent occupational categories that are widely sampled by MSHA inspectors. A small but statistically significant reduction in the overall mean respirable quartz dust and quartz concentrations from 1993 to 2010 was observed in most commodity groups. Variability from year to year and between commodities is high. Reduction in respirable quartz dust concentration does not necessarily correspond to a reduction in quartz concentration within the same commodity group. These trends are consistent with those reported in previous studies.

  3. Luminescent, optical and color properties of natural rose quartz

    Energy Technology Data Exchange (ETDEWEB)

    Kibar, R. [Department of Physics, Science Faculty, Ege University, 35100 Bornova-Izmir (Turkey); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal 2, Madrid 28006 (Spain); Cetin, A.; Selvi, S. [Department of Physics, Science Faculty, Ege University, 35100 Bornova-Izmir (Turkey); Karal, T. [Institute of Nuclear Science, Ege University, 35100 Bornova-Izmir (Turkey); Can, N. [Department of Physics, Faculty of Arts and Sciences, Celal Bayar University, 45140 Muradiye-Manisa (Turkey)], E-mail: cannurdogan@yahoo.com

    2007-11-15

    Rose quartz is an interesting mineral with numerous impurities that have been studied by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cathodoluminescence (CL), ion beam luminescence (IBL), radioluminescence (RL), thermoluminescence (TL) and optical absorption (OA). After HF etching, rose quartz from Oliva de Plasencia (Caceres, Spain) shows under SEM the presence of other silicate phases such as dumortierite [Al{sub 6.5-7}(BO{sub 3})(SiO{sub 4}){sub 3}(O,OH){sub 3}]. The OA spectrum of rose quartz suggests that these inclusions are the cause of coloration of rose quartz. The luminescence (CL, IBL, RL, TL) spectra behavior, at both room temperature and lower, confirms that the {approx}340nm emission could be associated with Si-O strain structures, including non-bridging oxygen or silicon vacancy-hole centers; the observed {approx}400nm emission could be associated with recombination of a hole trapped adjacent to a substitutional, charge-compensated aluminum alkali ion center; the {approx}500nm emission could be associated with substitutional Al{sup 3+} and the {approx}700nm peak could be associated with Fe{sup 3+} point defects in Si{sup 4+} sites. These results suggest that, while defect properties of rose quartz are not greatly dissimilar to those of purer forms of quartz and silica, further research seems necessary to determine criteria for the evolution of the newly-formed self-organized microstructures in the rose quartz lattice under irradiation.

  4. Characterization of impurities present on Tihimatine (Hoggar) quartz, Algeria

    Science.gov (United States)

    Anas Boussaa, S.; Kheloufi, A.; Boutarek Zaourar, N.

    2017-11-01

    Many of today's advanced materials depend on quartz as a raw material. Quartz usually contains abundant inclusions, both solid and liquid, and due to the number of these inclusions and their small size, complete separation is most difficult. Typical properties of raw quartz that must be characterized are: Size and Chemical composition of inclusions, their spatial distribution, localization of isomorphic substitutional elements (e.g. Al, Fe). The aim of this study has been to test experimental methods for investigating some inclusions (impurities) present in the Tihimatine quartz from El Hoggar region deposits (southern Algeria) using X Ray Fluorescence, scanning electron microscopy, optical Microscopy with reflected and transmitted lights, infra-red spectrometer, Raman spectrometer. Despite the high concentration of SiO2 in studied quartz reaching 98%, several harmful inclusions were found and identified as hematite, anatase, muscovite, graphite, it contains: Fe, Ti, Al, K, Ca. Some fluid inclusions were found. We detect the presence of carbon dioxide and water using raman spectroscopy. The repartition of solid impurities is aleatory and not homogeneous with maximum size of 10 μm. Concerning the fluid impurities, their diameter vary between 5 and 20 μm and their repartition is aleatory.

  5. Zircon-quartz-calcite segregations in carbonate-alkaline metasomatic rocks of the western Baikal region and their petrogenetic implications

    Science.gov (United States)

    Savelyeva, V. B.; Bazarova, E. P.; Sharygin, V. V.; Karmanov, N. S.

    2015-12-01

    Fine-grained segregations up to 5 mm in size composed of graphic intergrowths of zircon, quartz, calcite and containing up to 0.8 wt % SrO have been found in albite-riebeckite and dolomite-biotite metasomatic rocks formed after alaskite granite. They contain magnetite, titanomagnetite (25.4 wt % TiO2), cerite-(Ce,Nd), rutile (up to 1.2 wt % Nb2O5), as well as rare micrograins of monazite-(Ce), bastnaesite-(Ce), and barite (up to 5.7 wt % SrO). The fine-grained structure of mineral aggregates suggests a metacolloidal nature. It is assumed that the zircon-quartz-calcite assemblage was formed due to exchange decomposition reaction between the salt phase of hydrothermal solution with predominant Na2CO3, elevated Zr and, to a lesser extent, Fe, Ti, LREE, Nb contents and dissolved calcium and silica compounds of a Na2SiO3 type.

  6. Equivalent dose determination using a quartz isothermal TL signal

    DEFF Research Database (Denmark)

    Vandenberghe, D.A.G.; Jain, Mayank; Murray, A.S.

    2009-01-01

    We report on further developments in the use of an isothermal thermoluminescence (ITL) signal for determining the equivalent dose (De) in unheated sedimentary quartz. In order to minimise sensitivity change during the first measurement, the ITL signal is measured at 270 °C following a preheat...... agreement with the expected burial dose in samples from a variety of depositional environments and ages. Our results suggest that measurement of the ITL signal at 270 °C enables the quartz 325 °C TL peak to be used for accurate dose measurements on a single aliquot. The signal allows dating over at least...... the same age range as the OSL signal, and it appears especially advantageous for application to quartz samples for which the OSL signal saturates below 500 Gy....

  7. Effect of calcium phosphate addition on sintering of El-Oued sand quartz raw materials

    Directory of Open Access Journals (Sweden)

    L. Foughali

    2014-12-01

    Full Text Available This work addresses the development of an eventual low cost ceramic insulating or microfiltration membrane supports from inexpensive raw materials such Eloued quartz sand (EQS and calcium phosphate (CP using uniaxially dry compaction method. The prepared samples were sintered at different temperatures ranging between 1200 and 1550 ºC. Subsequently, the effects of sintering temperature and amount of CP on samples proprieties were investigated. It is observed that X-ray diffracion measurements confirmed that EQS was transformed into cristobalite and tridymite phases when both sintering temperature and holding time were increased. This transformation is favored with increasing amount of CP, it is observed also formation of CaSiO3 and Ca(Fe(AlPO4. The SEM images of the samples sintered at different temperatures illustrate that silica grains, CP grains, intergranular phase contents (Si, Ca, P, and O and an important open porosity depend on the sintering temperature. The porosity ratio changes in the range between 37% and 34% according to sintering temperature and to CP content; these values are in good agreement with SEM images. The thermal expansion behavior shows a weak expansion in the range of temperature between 600 and 1000 ºC which is situated between 1.27% and 1.33% (variation of 0.05% at 400 ºC.

  8. Transport of Sulfide-Reduced Graphene Oxide in Saturated Quartz Sand: Cation-Dependent Retention Mechanisms.

    Science.gov (United States)

    Xia, Tianjiao; Fortner, John D; Zhu, Dongqiang; Qi, Zhichong; Chen, Wei

    2015-10-06

    We describe how the reduction of graphene oxide (GO) via environmentally relevant pathways affects its transport behavior in porous media. A pair of sulfide-reduced GOs (RGOs), prepared by reducing 10 mg/L GO with 0.1 mM Na2S for 3 and 5 days, respectively, exhibited lower mobility than did parent GO in saturated quartz sand. Interestingly, decreased mobility cannot simply be attributed to the increased hydrophobicity and aggregation upon GO reduction because the retention mechanisms of RGOs were highly cation-dependent. In the presence of Na(+) (a representative monovalent cation), the main retention mechanism was deposition in the secondary energy minimum. However, in the presence of Ca(2+) (a model divalent cation), cation bridging between RGO and sand grains became the most predominant retention mechanism; this was because sulfide reduction markedly increased the amount of hydroxyl groups (a strong metal-complexing moiety) on GO. When Na(+) was the background cation, increasing pH (which increased the accumulation of large hydrated Na(+) ions on grain surface) and the presence of Suwannee River humic acid (SRHA) significantly enhanced the transport of RGO, mainly due to steric hindrance. However, pH and SRHA had little effect when Ca(2+) was the background cation because neither affected the extent of cation bridging that controlled particle retention. These findings highlight the significance of abiotic transformations on the fate and transport of GO in aqueous systems.

  9. Quartz red TL SAR equivalent dose overestimation for Chinese loess

    DEFF Research Database (Denmark)

    Lai, Z.P.; Murray, A.S.; Bailey, R.M.

    2006-01-01

    For the red TL of quartz extracted from Chinese loess, the single-aliquot regenerative-dose (SAR) procedure overestimates the known laboratory doses in dose recovery test. The overestimation is the result of the first heating during the measurement of natural TL signal causing a sensitivity...... reduction, which is not corrected for using a SAR protocol. The SARA procedure was used to measure the sensitivity change. Using this as a correction factor is tested by comparison with the quartz optically stimulated luminiscence (OSL) equivalent dose. SARA is also employed to determine the residual level...

  10. Chiral habit selection on nanostructured epitaxial quartz films.

    Science.gov (United States)

    Carretero-Genevrier, Adrián; Gich, Martí; Picas, Laura; Sanchez, Clément; Rodriguez-Carvajal, Juan

    2015-01-01

    Understanding the crystallization of enantiomorphically pure systems can be relevant to diverse fields such as the study of the origins of life or the purification of racemates. Here we report on polycrystalline epitaxial thin films of quartz on Si substrates displaying two distinct types of chiral habits that never coexist in the same film. We combine Atomic Force Microscopy (AFM) analysis and computer-assisted crystallographic calculations to make a detailed study of these habits of quartz. By estimating the surface energies of the observed crystallites we argue that the films are enantiomorphically pure and we briefly outline a possible mechanism to explain the habit and chiral selection in this system.

  11. Pressure effect on the sensitivity of quartz Bourdon tube gauges.

    Science.gov (United States)

    Szaniszlo, A. J.

    1972-01-01

    The sensitivity change for a commercial fused quartz Bourdon tube precision pressure gauge, due to a change in absolute pressure level, has been analytically computed and experimentally confirmed. The computed differential pressure error is 2.5% of full scale at a 100 atm absolute pressure level. The experimental method compared the fused quartz Bourdon tube gauge digital output to the results obtained from a nitrogen gas pressure system which had a high pressure, well-type mercury manometer as the differential pressure reference.

  12. Double acoustic microresonator quartz-enhanced photoacoustic spectroscopy.

    Science.gov (United States)

    Dong, Lei; Wu, Hongpeng; Zheng, Huadan; Liu, Yanyan; Liu, Xiaoli; Jiang, Wenzhe; Zhang, Lei; Ma, Weiguang; Ren, Wei; Yin, Wangbao; Jia, Suotang; Tittel, Frank K

    2014-04-15

    Quartz-enhanced photoacoustic spectroscopy (QEPAS) based on double acoustic microresonators (AmRs) is developed and experimentally investigated. The double AmR spectrophone configuration exhibits a strong acoustic coupling between the AmR and the quartz tuning fork, which results in a ∼5  ms fast response time. Moreover, the double AmRs provide two independent detection channels that allow optical signal addition or cancellation from different optical wavelengths and facilitate rapid multigas sensing measurements, thereby avoiding laser beam combination.

  13. Development of early diagenetic silica and quartz morphologies — Examples from the Siri Canyon, Danish North Sea

    Science.gov (United States)

    Weibel, Rikke; Friis, Henrik; Kazerouni, Afsoon Moatari; Svendsen, Johan B.; Stokkendal, Jesper; Poulsen, Mette Lise K.

    2010-07-01

    phases. Angular cavities in the microquartz coatings origin from dissolution of clinoptilolite, possibly with a source in volcanic ash, whereas dissolution of lepispheres probably resulted in circular cavities. Quartz ridges (syntaxial quartz overgrowths, a few micro millimetre in width, in parallel lines — defined in this paper). Quartz mountains (syntaxial, irregular 5-10 µm large quartz crystals — defined in this paper); developed in the water-filled sandstone intervals where fluids from the Central Graben were introduced, possibly together with the hydrocarbon, and where the continued growth was not retarded by the presence of hydrocarbons in the pore fluids. Macroquartz (syntaxial quartz overgrowths > 20 µm); seen as continued growths from quartz mountains. This takes place in the deeper reservoir sandstones, promoted by fluids originating from the Central Graben and increased burial depth. Quartz with sutured grain contacts; occurring only in the deepest well (3000 m).

  14. Deformation assisted by fluids in quartz veins of shear zones: an example from Iron Formations of Quadrilátero Ferrífero, Brazil.

    Science.gov (United States)

    Barbosa, Paola; Lagoeiro, Leonardo

    2013-04-01

    The evidences of fluid activity in rocks are well recognized. In many cases, the fluid is responsible to remobilize many elements (e.g. Au, Mn, Si) that may be transported over a long distance and precipitated as new minerals in regions of low stress of the rock. In many deformed rocks, the origin of a large number of structures (veins, pressure shadows, dissolved grain boundaries, etc) may be correlated to the fluid activity. However, the fluids are important not only during the crack-and-seal process but also after the sealing ceases. As an example of how the fluids are responsible to rearrange the structure of the rock, we studied many quartz veins of one iron-formation from Brazil. The rocks were collected in Quadrilátero Ferrífero (QF), Brazil, that is one of the most important metalogenetic provinces in the world. It is assumed the existence of a deformational and metamorphic gradient in the rocks of QF, increasing the occurrence of penetrative structures from southwest to northeast. However, the effects of the local shear zones in the deformation pattern of QF may not be neglected. Shear zones are generally recognized as structures that accommodate deformation, eventually with intense fluid percolation. It is indubitable that there is a relationship between the fluid activity and the deformation accommodation in shear zones. So, to investigate how the fluid activity can affect the mechanisms of accommodation of deformation in rocks of shear zones from QF, we characterized the crystallographic preferred orientation (CPO) of some quartz vein by EBSD (electron backscattering diffraction). All the samples came from the same outcrop and from the same dextral shear zone, localized in the low-deformation region of QF, under greenschist metamorphic conditions. The samples were oriented according to the XYZ reference system, with X parallel to the foliation and Z normal to the XY plane. The veins are quartz-rich layers parallel to the rock foliation. They do not

  15. Why do interstellar grains exist?

    Science.gov (United States)

    Seab, C. G.; Hollenbach, D. J.; Mckee, C. F.; Tielens, Alexander G. G. M.

    1986-01-01

    There exists a discrepancy between calculated destruction rates of grains in the interstellar medium and postulated sources of new grains. This problem was examined by modelling the global life cycle of grains in the galaxy. The model includes: grain destruction due to supernovae shock waves; grain injection from cool stars, planetary nebulae, star formation, novae, and supernovae; grain growth by accretion in dark clouds; and a mixing scheme between phases of the interstellar medium. Grain growth in molecular clouds is considered as a mechanism or increasing the formation rate. To decrease the shock destruction rate, several new physical processes, such as partial vaporization effects in grain-grain collisions, breakdown of the small Larmor radius approximation for betatron acceleration, and relaxation of the steady-state shock assumption are included.

  16. Coupling colour CL of quartz with multiple geochronological proxies in an attempt to determine extent of sediment recycling in Devonian and Mesozoic basins of southern Ireland

    Science.gov (United States)

    Fairey, Brenton; Tunwal, Mohit; Meere, Patrick; Mulchrone, Kieran

    2017-04-01

    Detrital zircon, mica and apatite ages from samples in the Lower Devonian Dingle Basin, the Middle to Upper Devonian Munster Basin and the Triassic to Cretaceous basins of the southern Irish offshore (North Celtic Sea, Fastnet and Goban Spur basins) indicate the potential of multiple cycles of sedimentation. However, this evidence is somewhat inconclusive and it remains a challenge to determine whether grains have been derived directly from the ultimate source or from recycling of older sedimentary rocks. Distinguishing between direct derivation of sediment and sediment recycling has important implications for prediction of sandstone maturity and hydrocarbon reservoir potential. Cathodoluminescence (CL) colour of quartz has, in the past, been used to determine the source of quartz in sandstones. However, the major concern for such an application is that there is large overlap of colours from different sources. In the present study, we hypothesise, based upon existing geochronological and petrographic evidence, that the Upper Devonian Munster Basin sedimentary rocks were recycled during Mesozoic times into the southern Irish offshore basins. In order to test this hypothesis, we compare the relative proportions of different CL colours in quartz from potential sedimentary sources (i.e. the Devonian Dingle and Munster basins), with those from Mesozoic offshore basins of southern Ireland. Similarity between relative proportions of quartz CL colours in these basins suggests recycling of sediments into the offshore basins during the Mesozoic.

  17. Etching quartz with inductively coupled plasma etching equipment

    Science.gov (United States)

    Wu, Xuming; Zhou, Changhe; Xi, Peng; Dai, Enwen; Ru, Huayi; Liu, Liren

    2003-11-01

    Inductively Coupled Plasma (ICP)can achieve high density plasma in low pressure,so it has a number of significant advantages such as improved etching rates,better profile control,improved uniformity, greatly increased selectivity and a dramatic reduction in radiation damage and contamination. In optics,quartz is an ideal optical material with transmitting spectral range from deep ultraviolet to far infrared.So we systematically studied the etching characteristics of quartz by using a Inductively Coupled Plasma (ICP)etching system.In the xperim nts,the gas was the mixture of CHF3,O2 and Ar,and the chamber pressure was about 10 mTorr.Th influences of gas flow rate and the power of the radio frequency on etching rate were optimized. The uniformity and repeatability of the etching technology were also studied. After residue mask material was removed by wet chemical solution, no polymer was observed on the surfaces of samples,and the surfaces of the fabricated quartz elements were smooth and clean. The optimized etching process is important for the fabrication of micro-optical lements based on quartz. Using this etching process, many gratings such as Dammann grating, rectangular groove grating, and optical disk grating can be fabricated successfully.

  18. Evaluation of trapping parameters of annealed natural quartz

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Rui [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Shisanling Seismic Station, Institute of Earthquake Science, CEA, 102200 Beijing (China); Wei, Ming-Jian, E-mail: weimj@cnu.edu.cn [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Song, Bo [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Beijing Jing Yuan School, 100040 Beijing (China); Zhang, Yan [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); School of TaiPingqiao, Nan Lu of West Railway Station, 100073 Beijing (China); Zhao, Qiu-Yue [Key Laboratory of Tourism and Resources Environment in Universities of Shandong, Taishan University, 271000 Tai’an (China); Pan, Bao-Lin; Li, Teng-Fei [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China)

    2016-05-15

    The thermoluminescence (TL) trapping parameters of annealed quartz have been investigated. The apparent TL peaks observed at temperatures of 133 °C, 211 °C, 266 °C and 405 °C, respectively, were named Peak I, Peak II, Peak III and Peak IV. The T{sub m} − T{sub stop} method is applied to investigate the number of peaks and their positions, and to obtain the trap distributions in the quartz. Peak shape (PS), Hoogenstraaten method (Various Heating Rates Method, VHR), and Computerized Glow Curve Deconvolution (CGCD) are used to evaluate the trapping parameters of the annealed quartz. The glow curve can be considered as a superposition of at least nine overlapping peaks. These peaks show up at 133 °C, 211 °C, 266 °C, 308 °C, 333 °C, 384 °C, 441 °C, 466 °C and 484 °C. The PS method can be only used in evaluating the parameters for Peaks I. The VHR method can be used in evaluating the trapping parameters for the first three peaks. CGCD method is complementary to obtaining parameters for the sub-peaks, and the thermal quenching correction with the Urbach’s method is necessary. The Urbach’s coefficient for the quartz is 30.03 kT{sub m}.

  19. Triplet states at an O vacancy in alpha-quartz

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper

    2002-01-01

    The energy landscape of an alpha-quartz O vacancy in the lowest triplet state is investigated. Four local minima are identified and geometries, total energies, and electron paramagnetic resonance (EPR) parameters are obtained. On the basis of calculated values for the magnetic dipole interaction...

  20. Influence of Quartz Fillers in Dielectric Composites on Electrostrictive Sensors

    Directory of Open Access Journals (Sweden)

    B.Shivamurthy

    2008-05-01

    Full Text Available In this investigation E-glass epoxy composite filled with different amount of quartz powder were prepared by compression moulding and hot curing. Plain waived E-glass cloth with density 200gm / meter square was used as reinforcement. Epoxy resin LY556 mixed with Hardener HT907 and accelerator DY063 in the ratio 100:80:2 was used as matrix. The quartz powder of 30 microns particle size was used as fillers. Four types of composites were prepared with different amount of quartz fillers like 0%, 3%, 6% and 9% with unchanged reinforcement. For all the samples, dielectric dissipation factor (tan δ, dielectric constant and a. c. conductivity and electrostriction have been measured by using a LCR meter at 1 KHz frequency. The phenomenon of electrostriction was examined for all samples (of different percentage of quartz filled composites. It is observed that the percentage of filler influences the electrostriction phenomena in the composites. The 6 % filler content composites samples exhibits the improved electrostriction phenomenon required for sensors compared to other types of composites.

  1. Characterization of silica quartz as raw material in photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Boussaa, S. Anas, E-mail: sabiha.anas@gmail.com; Kheloufi, A.; Kefaifi, A.; Kerkar, F. [Division croissance cristalline et procédés métallurgiques CCPM Centre de recherche en technologie des semi-conducteurs pour l’énergétique (C.R.T.S.E) 02 Bd Frantz Fanon BP. 140 Alger 7 merveilles, Alger 16200 (Algeria); Zaourar, N. Boutarek [Laboratoire des technologies des matériaux, USTHB, B.P. 32 El Alia, Bab Ezzouar, Alger, Algérie 16111 (Algeria)

    2016-07-25

    Raw materials are essential for the functioning of modern societies, and access to these raw materials is vital to the world economy. Sustainable development, both globally level, raises important new challenges associated with access and efficient use of raw materials. High purity quartz, is consider as a critical raw material and it is a rare commodity that only forms under geological conditions where a narrow set of chemical and physical parameters is fulfilled. When identified and following special beneficiation techniques, high purity quartz obtains very attractive prices and is applied in high technology sectors that currently are under rapid expansion such as photovoltaic solar cells, silicon metal - oxide wafers in the semiconductor industry and long distance optical fibers that are used in communication networks. Crystalline silicon remains the principal material for photovoltaic technology. Metallurgical silicon is produced industrially by the reduction of silica with carbon in an electric arc furnace at temperatures higher than 2000 °C in the hottest parts, by a reaction that can be written ideally as: SiO{sub 2} + 2C = Si + 2CO. The aim of this study has been to test experimental methods for investigating the various physical and chemical proprieties of Hoggar quartz with different techniques: X Ray Fluorescence, infra-red spectroscopy, Scanning Electron Microscopy, Optic Microscopy, Carbon Analyzer and Vickers Hardness. The results show finally that the quartz has got good result in purity but need enrichment for the photovoltaic application.

  2. Meteorological factors in the Quartz Creek forest fire

    Science.gov (United States)

    H. T. Gisborne

    1927-01-01

    It is not often that a large forest fire occurs conveniently near a weather station specially equipped for measuring forest-fire weather. The 13,000-acre Quartz Creek fire on the Kaniksu National Forest during the summer of 1936 was close enough to the Priest River Experimental Forest of the Northern Rocky Mountain Forest Experiment Station for the roar of the flumes...

  3. Characterization of silica quartz as raw material in photovoltaic applications

    Science.gov (United States)

    Boussaa, S. Anas; Kheloufi, A.; Zaourar, N. Boutarek; Kefaifi, A.; Kerkar, F.

    2016-07-01

    Raw materials are essential for the functioning of modern societies, and access to these raw materials is vital to the world economy. Sustainable development, both globally level, raises important new challenges associated with access and efficient use of raw materials. High purity quartz, is consider as a critical raw material and it is a rare commodity that only forms under geological conditions where a narrow set of chemical and physical parameters is fulfilled. When identified and following special beneficiation techniques, high purity quartz obtains very attractive prices and is applied in high technology sectors that currently are under rapid expansion such as photovoltaic solar cells, silicon metal - oxide wafers in the semiconductor industry and long distance optical fibers that are used in communication networks. Crystalline silicon remains the principal material for photovoltaic technology. Metallurgical silicon is produced industrially by the reduction of silica with carbon in an electric arc furnace at temperatures higher than 2000 °C in the hottest parts, by a reaction that can be written ideally as: SiO2 + 2C = Si + 2CO. The aim of this study has been to test experimental methods for investigating the various physical and chemical proprieties of Hoggar quartz with different techniques: X Ray Fluorescence, infra-red spectroscopy, Scanning Electron Microscopy, Optic Microscopy, Carbon Analyzer and Vickers Hardness. The results show finally that the quartz has got good result in purity but need enrichment for the photovoltaic application.

  4. Symmetry and Piezoelectricity: Evaluation of $\\alpha$-Quartz coefficients

    OpenAIRE

    Tannous, C.

    2017-01-01

    Piezoelectric coefficients of $\\alpha$-Quartz are derived from symmetry arguments based on Neumann's Principle with three different methods: Fumi, Landau-Lifshitz and Royer-Dieulesaint. While Fumi method is tedious and Landau-Lifshitz requires additional physical principles to evaluate the piezoelectric coefficients, Royer-Dieulesaint is the most elegant and most efficient of the three techniques.

  5. Absorbed dose evaluations in retrospective dosimetry: Methodological developments using quartz

    DEFF Research Database (Denmark)

    Bailiff, I.K.; Bøtter-Jensen, L.; Correcher, V.

    2000-01-01

    Dose evaluation procedures based on luminescence techniques were applied to 50 quartz samples extracted from bricks that had been obtained from populated or partly populated settlements in Russia and Ukraine downwind of the Chernobyl NPP. Determinations of accrued dose in the range similar to 30...

  6. Speciation and phase separation of water in quartz (A review ...

    African Journals Online (AJOL)

    Speciation, supersaturation and phase separation of water in hydrothermal grown (synthetic) quartz cryst-als have been examined as fundamental issues determining clustering, nucleation and bubble formation, which have profound influence on hydrolytic weakening, dislocation-bubble interactions and high temperature ...

  7. Application of quartz crystal microbalance technology in tribological investigation

    Science.gov (United States)

    The last fifteen years have seen considerable growth in the application of quartz crystal microbalance (QCM) to explore the tribological characteristics of materials. This article reviews some of the advances made in characterizing frictional properties of materials using the QCM, especially with di...

  8. Quartz-like Crystals Found in Planetary Disks

    Science.gov (United States)

    2008-01-01

    NASA's Spitzer Space Telescope has, for the first time, detected tiny quartz-like crystals sprinkled in young planetary systems. The crystals, which are types of silica minerals called cristobalite and tridymite, can be seen close-up in the black-and-white insets (cristobalite is on the left, and tridymite on the right). The main picture is an artist's concept of a young star and its swirling disk of planet-forming materials. Cristobalite and tridymite are thought to be two of many planet ingredients. On Earth, they are normally found as tiny crystals in volcanic lava flows and meteorites from space. These minerals are both related to quartz. For example, if you were to heat the familiar quartz crystals often sold as mystical tokens, the quartz would transform into cristobalite and tridymite. Because cristobalite and tridymite require rapid heating and cooling to form, astronomers say they were most likely generated by shock waves traveling through the planetary disks. The insets are Scanning Electron Microscope pictures courtesy of George Rossman of the California Institute of Technology, Pasadena, Calif.

  9. Quartz crystal microbalance gas sensor with nanocrystalline diamond sensitive layer

    Czech Academy of Sciences Publication Activity Database

    Varga, Marián; Laposa, A.; Kulha, Pavel; Kroutil, J.; Husák, M.; Kromka, Alexander

    2015-01-01

    Roč. 252, č. 11 (2015), s. 2591-2597 ISSN 0370-1972 R&D Projects: GA ČR(CZ) GBP108/12/G108 Institutional support: RVO:68378271 Keywords : gas sensor * nanocrystalline diamond * quartz resonator * thickness shear mode Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 1.522, year: 2015

  10. Geology and geochemistry of giant quartz veins from the ...

    Indian Academy of Sciences (India)

    They show imprints of strong brittle to ductile–brittle deformation, and in places are associated with base metal and gold incidences, and pyrophyllite-diaspore mineralization. The geochemistry of giant quartz veins were studied. Apart from presenting new data on the geology and geochemistry of these veins, an attempt has ...

  11. Grain Size Distribution in Mudstones: A Question of Nature vs. Nurture

    Science.gov (United States)

    Schieber, J.

    2011-12-01

    Grain size distribution in mudstones is affected by the composition of the source material, the processes of transport and deposition, and post-depositional diagenetic modification. With regard to source, it does make a difference whether for example a slate belt is eroded vs a stable craton. The former setting tends to provide a broad range of detrital quartz in the sub 62 micron size range in addition to clays and greenschist grade rock fragments, whereas the latter may be biased towards coarser quartz silt (30-60 microns), in addition to clays and mica flakes. In flume experiments, when fine grained materials are transported in turbulent flows at velocities that allow floccules to transfer to bedload, a systematic shift of grain size distribution towards an increasingly finer grained suspended load is observed as velocity is lowered. This implies that the bedload floccules are initially constructed of only the coarsest clay particles at high velocities, and that finer clay particles become incorporated into floccules as velocity is lowered. Implications for the rock record are that clay beds deposited from decelerating flows should show subtle internal grading of coarser clay particles; and that clay beds deposited from continuous fast flows should show a uniform distribution of coarse clays. Still water settled clays should show a well developed lower (coarser) and upper (finer) subdivision. A final complication arises when diagenetic processes, such as the dissolution of biogenic silica, give rise to diagenetic quartz grains in the silt to sand size range. This diagenetic silica precipitates in fossil cavities and pore spaces of uncompacted muds, and on casual inspection can be mistaken for detrital quartz. In distal mudstone successions close to 100 % of "apparent" quartz silt can be of that origin, and reworking by bottom currents can further enhance a detrital perception by producing rippled and laminated silt beds. Although understanding how size

  12. Grain Boundary Segregation in Metals

    CERN Document Server

    Lejcek, Pavel

    2010-01-01

    Grain boundaries are important structural components of polycrystalline materials used in the vast majority of technical applications. Because grain boundaries form a continuous network throughout such materials, their properties may limit their practical use. One of the serious phenomena which evoke these limitations is the grain boundary segregation of impurities. It results in the loss of grain boundary cohesion and consequently, in brittle fracture of the materials. The current book deals with fundamentals of grain boundary segregation in metallic materials and its relationship to the grain boundary structure, classification and other materials properties.

  13. Effect of grain size and angularity on seismic velocity in unconsolidated sediment

    Science.gov (United States)

    Keshvardoost, R.; Lorenzo, J. M.; Bonal, N.; Patterson, D.

    2016-12-01

    Near surface seismic interpretation of weathering profiles in crystalline rock assumes a seismic response controlled by multiple factors, including mineral grain shape, size distribution, packing, composition, burial depth and pore fluids. In particular, we consider experimentally in the lab, the role particle angularity and grain size may play in the observed P-wave velocity. We estimate P-wave velocity in 'sand' boxes (0.49 × 0.35 × 0.25 m) that contain homogeneous, angular, crushed, quartz sand and silt of 8 different mean grain sizes, ranging from 0.04 to 1.2 mm, as well as a glass-bead reference case. We use an in-house, calibrated, piezo-ceramic stack as a seismic source and a piezo-electric-film as a sensor (1- 5 kHz). In dry conditions, preliminary results imply a power-law relationship between Vp and average angular grain size and a larger transmission velocity for the rounded beads, despite their lower moduli. We consider a modified Biot model as well as the Hertz-Mindlin model to predict seismic velocity in angular quartz of different grain sizes and fluid content.

  14. Piezoelectrically forced vibrations of rectangular SC-cut quartz plates

    Science.gov (United States)

    Lee, P. C. Y.; Lin, W. S.

    1998-06-01

    A system of two-dimensional first-order equations for piezoelectric crystal plates with general symmetry and with electroded faces was recently deduced from the three-dimensional equations of linear piezoelectricity. Solutions of these equations for AT-cut plates of quartz were shown to give accurate dispersion curves without corrections, and the resonances predicted agree closely with the experimental data of Koga and Fukuyo [I. Koga and H. Fukuyo, J. Inst. Electr. Commun. Eng. Jpn. 36, 59 (1953)] and that of Nakazawa, Horiuchi, and Ito (M. Nakazawa, K. Horiuchi, and H. Ito, Proceedings of the 1990 IEEE Ultrasonics Symposium, pp. 547-555). In this article, these equations are employed to study the free as well as the forced vibrations of doubly rotated quartz plates. Solutions of straight-crested vibrational modes varying in the x1 and x3 directions of SC-cut quartz plates of infinite extent are obtained and from which dispersion curves are computed. Comparison of those dispersion curves with those from the three-dimensional equations shows that the agreement is very close without any corrections. Resonance frequencies for free vibrations and capacitance ratios for piezoelectrically forced vibrations are computed and examined for various length-to-thickness or width-to-thickness ratios of rectangular SC-cut quartz plates. The capacitance ratio as a function of forcing frequency is computed for a rectangular AT-cut quartz and compared with the experimental data of Seikimoto, Watanabe, and Nakazawa (H. Sekimoto, Y. Watanabe, and M. Nakazawa, Proceedings of the 1992 IEEE Frequency Control Symposium, pp. 532-536) and is in close agreement.

  15. Fracture flow due to hydrothermally induced quartz growth

    Science.gov (United States)

    Kling, Tobias; Schwarz, Jens-Oliver; Wendler, Frank; Enzmann, Frieder; Blum, Philipp

    2017-09-01

    Mineral precipitations are a common feature and limitation of initially open, permeable rock fractures by forming sealing structures or secondary roughness in open voids. Hence, the objective of this numerical study is the evaluation of hydraulic properties of fractures sealed by hydrothermally induced needle and compact quartz growth. Phase-field models of progressive syntaxial and idiomorphic quartz growth are implemented into a fluid flow simulation solving the Navier-Stokes equation. Flow simulations for both quartz types indicate an obvious correlation between changes in permeability, fracture properties (e.g. aperture, relative roughness and porosity) and crystal growth behavior, which also forms distinct flow paths. Thus, at lower sealing stages initial fracture permeability significantly drops down for the 'needle fracture' forming highly tortuous flow paths, while the 'compact fracture' records a considerably smaller loss. Fluid flow in both sealing fractures most widely is governed by a ;parallel plate;-like cubic law behavior. However, the 'needle fracture' also reveals flow characteristics of a porous media. A semi-theoretical equation is introduced that links geometrical (am) with hydraulically effective apertures (ah) and the relative fracture roughness. For this purpose, a geometry factor α is introduced being α = 2.5 for needle quartz and α = 1.0 for compact quartz growth. In contrast to most common ah-am-relationships this novel formulation not only reveals more precise predictions for the needle (RMSE = 1.5) and the compact fractures (RMSE = 3.2), but also exhibit a larger range of validity concerning the roughness of the 'needle' (σ/am = 0-2.4) and the 'compact fractures' (σ/am = 0-1.8).

  16. Influence of grain size and grain boundary recombination velocity on ...

    African Journals Online (AJOL)

    The plot of the diffusion capacitance allowed us to study the influence of the following parameters: grain size, grain boundary recombination velocity, junction recombination velocity and illumination wavelength on this capacitance. This study pointed out that junction and grain boundary recombination velocities play an ...

  17. A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy Applications

    Directory of Open Access Journals (Sweden)

    Tomasz Starecki

    2017-11-01

    Full Text Available All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

  18. A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications.

    Science.gov (United States)

    Starecki, Tomasz; Wieczorek, Piotr Z

    2017-11-03

    All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

  19. FINE GRAIN NUCLEAR EMULSION

    Science.gov (United States)

    Oliver, A.J.

    1962-04-24

    A method of preparing nuclear track emulsions having mean grain sizes less than 0.1 microns is described. The method comprises adding silver nitrate to potassium bromide at a rate at which there is always a constant, critical excess of silver ions. For minimum size grains, the silver ion concentration is maintained at the critical level of about pAg 2.0 to 5.0 during prectpitation, pAg being defined as the negative logarithm of the silver ion concentration. It is preferred to eliminate the excess silver at the conclusion of the precipitation steps. The emulsion is processed by methods in all other respects generally similar to the methods of the prior art. (AEC)

  20. EXTRACTION OF CRISTOBALITE FROM MILKY-WHITE FORMS OF QUARTZ STUFF1

    OpenAIRE

    Issaev, V.; Oreshnikova, N.

    1997-01-01

    Natural quartz is one of die main sources of getting a unique material - quartz glass. Wide application of quartz glass in chemical and electronic industry, aviation and cosmonautics, fibre optics and computer techniques makes it absolutely indispensable. However, industrial reserves of rock-chrystal lodes, that is die most pure source of quartz stuff with minimal mineral admixturer, are practically exhausted everywhere. All this results in usage of.low quality stuff and, thus, to significant...

  1. Properties and behavior of quartz for the silicon process

    Energy Technology Data Exchange (ETDEWEB)

    Aasly, Kurt

    2008-07-01

    This PhD-thesis is a result of the study on important properties of quartz as a raw material for the metallurgical production of ferrosilicon and silicon metal. This includes defining mechanical properties important for the size reduction experienced during transport and storage and thermo-mechanical properties of quartz that is important for how the quartz reacts to the high temperatures experienced as it is charged on the furnace. Additionally, softening properties of quartz have been briefly discussed in some of the papers. Another important goal has been to test analytical and experimental methods for investigating the various properties. The investigations of important factors for the mechanical properties of ores and industrial minerals have been carried out as a literature study. The mining operation and transport from mine to smelter has been discussed and several factors that are significant for achieving best possible mechanical properties of the quartz have been identified. The most important factors are related to production in the mine and processing plant, which should be carefully planned to minimize the amount of blast-induced damage in the rock and thus achieve the best possible mechanical strength of the raw material. The amount of fines can be minimized by controlling the handling of the raw materials during the transport and storage. It is especially important to avoid high drops, both high single drops and accumulated height of all the drops in total. Investigations of the thermo-mechanical properties of quartz have been carried out by using different experimental and characterization methods. The petrographic investigations of the raw materials by polarized light microscopy have been important. Thermo-mechanical investigations have been high-temperature microthermometry and shock heating of quartz samples in an induction furnace with subsequent investigations of the heated material. The subsequent investigation included polarized- and

  2. Grain alcohol study: summary

    Energy Technology Data Exchange (ETDEWEB)

    The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentation demand; the optimizaton of value of agricultural crops; and the efficiencies of combining related industries. Ahydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grain can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural- environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.

  3. Grain alcohol study: summary

    Energy Technology Data Exchange (ETDEWEB)

    The study has concentrated upon a detailed examination of all considerations involved in the production, use, and marketing of ethyl alcohol (Ethanol) as produced from the fermentation of agricultural grains. Each parameter was examined in the light of current energy markets and trends; new sources and technological, and processes for fermentation, the capability of the agricultural industry to support fermentaton demand; the optimization of value of agricultureal crops; and the efficiencies of combining related industries. Anhydrous (200 proof) ethanol makes an excellent blending component for all present automotive fuels and an excellent octane additive for unleaded fuels in proportions up to 35% without requiring modifications to current engines. There is no difference between ethanol produced by fermentation and ethanol produced synthetically from petroleum. The decision to produce ethanol one way or the other is purely economic. The agricultural industry can support a major expansion in the fermentation industry. The residue (distillers grains) from the fermentation of corn for ethanol is an excellent and economical feed for livestock and poultry. A reliable supply of distillers grains can assist in making the large beef feedlot operations more economically viable. The source materials, fuels, products and by-products of an ethanol plant, beef feedlot, gas biodigester plant, municipal waste recovery plant and a steam generated electrical plant are interrelated and mutually beneficial for energy efficiencies and economic gains when co-located. The study concludes that the establishment of such agricultural-environment industrial energy complexes, would provide a broad range of significant benefits to Indiana.

  4. Interaction of aluminum projectiles with quartz sand in impact experiments: Formation of khatyrkite (CuAl2) and reduction of SiO2 to Si

    Science.gov (United States)

    Hamann, Christopher; Stöffler, Dieter; Reimold, Wolf Uwe

    2016-11-01

    We analyzed the interaction of spherical, 6.36-mm-diameter, Cu-bearing aluminum projectiles with quartz sand targets in hypervelocity impact experiments performed at NASA Ames Vertical Gun Range. Impact velocities and inferred peak shock pressures varied between 5.9 and 6.5 km/s and ∼41 and 48 GPa, respectively. Shocked particles (;impact melt particles;) coated with thin crusts of molten projectile material were recovered from the floors of the ca. 33-cm-diameter craters and the respective ejecta blankets. Through petrographic and chemical (optical microscopy, FE-EMPA, SEM-EDX, and XRF) analysis we show that these particles have a layered structure manifested in distinct layers of decreasing shock metamorphism. These can be characterized by the following physical and chemical reactions and alteration products: (i) complete melting and subsequent recrystallization of the projectile, forming a distinct crystallization texture in the fused metal crust; (ii) projectile-target mixing, involving a redox reaction between Cu-bearing Al alloy und SiO2, leading to formation of khatyrkite (CuAl2), Al2O3 melt, euhedral silicon crystals, and spherical droplets of silicon; (iii) melting of quartz to lechatelierite and formation of planar deformation features in relic quartz grains; and (iv) shock lithification of quartz grains with fracturing of grains, grain-boundary melting, planar deformation features, and complete loss of porosity. To our knowledge, this is the first report of khatyrkite formed experimentally in hypervelocity impact experiments. These results have implications for the understanding of a similar redox reaction between Al-Cu metal and siliceous impact melt recently postulated for the Khatyrka CV3 carbonaceous chondrite. Moreover, these results bear on the processes that lead to layers of regolith on the surfaces of planetary bodies without atmospheres, such as asteroids in the main belt (e.g., 4 Vesta), and on the Moon. Specifically, impacts of mm

  5. Progress report on grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of X-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed.

  6. Progress report on grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Balluffi, R.W.; Bristowe, P.D.

    1989-06-01

    The research was focused on the following three major areas: (1) study of the atomic structure of grain boundaries by means of x-ray diffraction, transmission electron microscopy and computer modeling; (2) study of grain boundary phase transitions by electron microscopy and computer modeling; (3) investigation of the mechanism of high angle grain boundary migration. Results are briefly discussed. 20 refs.

  7. Simulation of Pressure Induced Phase Transition and Modulated Structures of Quartz

    OpenAIRE

    Sergey V., DMITRIEV; Miki, YAJIMA; Yoshiya, MAKITA; Kohji, ABE; Takeshi, SHIGENARI; Department of Applied Physics and Chemistry, University of Electro-Communications; Department of Applied Physics and Chemistry, University of Electro-Communications; Department of Applied Physics and Chemistry, University of Electro-Communications; Department of Applied Physics and Chemistry, University of Electro-Communications; Department of Applied Physics and Chemistry, University of Electro-Communications

    2000-01-01

    In the vicinity of α⟷β transition in quartz there exists an incommensurate phase. We perform numerical calculations to obtain the phase diagram of quartz and estimate the period of modulation. The results show that modulation phase with a short period is preferable in contrast to the currently accepted interpretation of incommensurate phase in quartz.

  8. 30 CFR 71.101 - Respirable dust standard when quartz is present.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Respirable dust standard when quartz is present... UNDERGROUND COAL MINES Dust Standards § 71.101 Respirable dust standard when quartz is present. When the respirable dust in the mine atmosphere of the active workings contains more than 5 percent quartz, the...

  9. 30 CFR 90.101 - Respirable dust standard when quartz is present.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Respirable dust standard when quartz is present... quartz is present. When the respirable dust in the mine atmosphere of the active workings to which a Part 90 miner is exposed contains more than 5 percent quartz, the operator shall continuously maintain the...

  10. 75 FR 30282 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes

    Science.gov (United States)

    2010-06-01

    ...-008-AD; Amendment 39-16312; AD 2010-11-07] RIN 2120-AA64 Airworthiness Directives; Quartz Mountain... Quartz Mountain Aerospace, Inc. Model 11E airplanes. This AD requires you to clean and lubricate the... publications listed in this AD. ADDRESSES: Quartz Mountain Aerospace, Inc. is in liquidation. For service/or...

  11. 30 CFR 70.101 - Respirable dust standard when quartz is present.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Respirable dust standard when quartz is present... Respirable dust standard when quartz is present. When the respirable dust in the mine atmosphere of the active workings contains more than 5 percent quartz, the operator shall continuously maintain the average...

  12. 75 FR 12468 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes

    Science.gov (United States)

    2010-03-16

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Quartz Mountain... airworthiness directive (AD) for all Quartz Mountain Aerospace, Inc. Model 11E airplanes. This proposed AD would... 5 p.m., Monday through Friday, except Federal holidays. Quartz Mountain Aerospace, Inc. is in...

  13. Some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening

    Science.gov (United States)

    Bahadur, H.; Parshad, R.

    1983-01-01

    The paper reports some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening. The present results show how the frequency shift in quartz crystals can be influenced by heat processing prior to irradiation and how this procedure can lead to radiation hardening for obtaining precise frequencies and time intervals from quartz oscillators in space.

  14. Cancer morbidity and quartz exposure in Swedish iron foundries.

    Science.gov (United States)

    Westberg, Håkan; Andersson, Lena; Bryngelsson, Ing-Liss; Ngo, Yen; Ohlson, Carl-Göran

    2013-07-01

    The aim of this study was to determine cancer morbidity amongst Swedish iron foundry workers with special reference to quartz exposure. In addition to respirable dust and quartz, phenol, formaldehyde, furfuryl alcohols, polycyclic aromatic hydrocarbons (PAHs), carbon black, isocyanates and asbestos are used or generated by foundry production techniques and exposure to any of these substances could have potentially carcinogenic effects. Cancer morbidity between 1958 and 2004 was evaluated in a cohort of 3,045 male foundry workers employed for >1 year between 1913 and 2005. Standardised incidence ratios (SIRs) with 95 % confidence intervals (95 % CI) were determined by comparing observed numbers of incident cancers with frequencies in the Swedish cancer register. Exposure measures were assessed using information from the personal files of employees and modelling quartz measurement based on a database of 1,667 quartz measurements. Dose responses for lung cancer were determined for duration of employment and cumulative quartz exposure for latency periods >20 years. Overall cancer morbidity was not increased amongst the foundry workers (SIR 1.00; 95 % CI, 0.90-1.11), but the incidence of lung cancer was significantly elevated (SIR 1.61; 95 % CI, 1.20-2.12). A non-significant negative dose response was determined using external comparison with a latency period of >20 years (SIR 2.05, 1.72 1.26 for the low, medium and high exposure groups), supported by internal comparison data (hazard ratios 1, 1.01, 0.78) for the corresponding groups. For cancers at sites with at least five observed cases and a SIR > 1.25, non-significant risks with SIRs > 1.5 were determined for cancers of the liver, larynx, testis, connective muscle tissue, multiple myeloma plasmacytoma and lymphatic leukaemia. A significant overall risk of lung cancer was determined, but using external and internal comparison groups could not confirm any dose response at our cumulative quartz dose levels.

  15. Special Grain Boundaries in Ultrafine-Grained Tungsten

    Science.gov (United States)

    Dudka, O. V.; Ksenofontov, V. A.; Sadanov, E. V.; Starchenko, I. V.; Mazilova, T. I.; Mikhailovskij, I. M.

    2016-07-01

    Field ion microscopy and computer simulation were used for the study of an atomic structure high-angle grain boundary in hard-drawn ultrafine-grained tungsten wire. These boundaries with special misorientations are beyond the scope of the coincident site lattice model. It was demonstrated that the special non-coincident grain boundaries are the plane-matching boundaries, and rigid-body displacements of adjacent nanograins are normal to the misorientation axis. The vectors of rigid-body translations of grains are described by broad asymmetric statistical distribution. Mathematical modeling showed that special incommensurate boundaries with one grain oriented along the {211} plane have comparatively high cohesive energies. The grain-boundary dislocations ½ were revealed and studied at the line of local mismatch of {110} atomic planes of adjacent grains.

  16. The red, white and blue of quartz luminescence: A comparison of D{sub e} values derived for sediments from Australia and Indonesia using thermoluminescence and optically stimulated luminescence emissions

    Energy Technology Data Exchange (ETDEWEB)

    Westaway, K.E. [Department of Environment and Geography, Faculty of Science, Macquarie University, NSW 2109 (Australia)], E-mail: kira@els.mq.edu.au

    2009-05-15

    Heated quartz, including quartz from volcanic provinces, commonly displays different luminescence characteristics compared with the same mineral in non-volcanic contexts. These differing properties demand thorough investigations into the most suitable dating techniques for samples composed of quartz grains with different origins. In cave settings, independent techniques such as radiocarbon and U-series can prove useful for validating results, but further insights may be gained by comparing the results obtained for quartz using different luminescence emissions. Twenty-two quartz samples have been selected from five areas (Australia, Timor, Flores, Java and Sulawesi) for comparison of the red and blue emissions. The dual-aliquot regenerative-dose protocol was used to estimate the equivalent dose (D{sub e}) associated with the light-sensitive red thermoluminescence while the single aliquot regenerative-dose protocol was used to measure the D{sub e} values for single grains and single aliquots, which were optically stimulated by green or blue light, respectively. The results obtained from the red thermoluminescence and optically stimulated luminescence measurements display good agreement with independent dating techniques (within {approx}20%). However, the blue emissions exhibit a thermally unstable component, which causes a large underestimation in palaeodoses (on average {approx}80%) and an age limit of {approx}25 ka, while the red emissions are more thermally stable over geological timescales but produce an overestimation in red TL ages (by {approx}13 ka) and low precision (typically {approx}24%). These results can be correlated to three different quartz groups, which have been divided according to their luminescence emissions.

  17. A Multi-Fork Z-Axis Quartz Micromachined Gyroscope

    Directory of Open Access Journals (Sweden)

    Aiying Yang

    2013-09-01

    Full Text Available A novel multi-fork z-axis gyroscope is presented in this paper. Different from traditional quartz gyroscopes, the lateral electrodes of the sense beam can be arranged in simple patterns; as a result, the fabrication is simplified. High sensitivity is achieved by the multi-fork design. The working principles are introduced, while the finite element method (FEM is used to simulate the modal and sensitivity. A quartz fork is fabricated, and a prototype is assembled. Impedance testing shows that the drive frequency and sense frequency are similar to the simulations, and the quality factor is approximately 10,000 in air. The scale factor is measured to be 18.134 mV/(°/s and the nonlinearity is 0.40% in a full-scale input range of ±250 °/s.

  18. A Multi-Fork Z-Axis Quartz Micromachined Gyroscope

    Science.gov (United States)

    Feng, Lihui; Zhao, Ke; Sun, Yunan; Cui, Jianmin; Cui, Fang; Yang, Aiying

    2013-01-01

    A novel multi-fork z-axis gyroscope is presented in this paper. Different from traditional quartz gyroscopes, the lateral electrodes of the sense beam can be arranged in simple patterns; as a result, the fabrication is simplified. High sensitivity is achieved by the multi-fork design. The working principles are introduced, while the finite element method (FEM) is used to simulate the modal and sensitivity. A quartz fork is fabricated, and a prototype is assembled. Impedance testing shows that the drive frequency and sense frequency are similar to the simulations, and the quality factor is approximately 10,000 in air. The scale factor is measured to be 18.134 mV/(°/s) and the nonlinearity is 0.40% in a full-scale input range of ±250 °/s. PMID:24048339

  19. New developments in THz quartz enhanced photoacoustic spectroscopy

    Science.gov (United States)

    Spagnolo, Vincenzo; Patimisco, Pietro; Sampaolo, Angelo; Giglio, Marilena; Vitiello, Miriam S.; Scamarcio, Gaetano; Tittel, Frank K.

    2016-09-01

    We will report on new developments of quartz-enhanced photo-acoustic (QEPAS) sensor employing THz quantum cascade laser (QCLs). The extension of the QEPAS technique in the THz range was made possible by the realization of custom made QTFs. With the aim to improve the QTF acousto-electric transduction efficiency, we designed and realized new QTF designs. A detailed analysis of the quality factor, the resonance frequency and the electrical resistance of custom quartz tuning forks (QTFs) with different geometrical parameters is reported. The custom QTFs were employed in QEPAS sensors using THz QCLs as the laser excitation sources and targeting CH3OH and H2S. Minimum detection limits of a few tens of ppb and normalized noise equivalent absorption factors down to 3.75×10-11 cm-1W/Hz½ were achieved.

  20. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy.

    Science.gov (United States)

    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S; Beere, Harvey E; Ritchie, David A; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2016-03-25

    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH₃OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a 3.93 THz quantum cascade laser as the excitation source in resonance with a CH₃OH rotational absorption line located at 131.054 cm(-1). A minimum detection limit of 160 ppb in 30 s integration time, corresponding to a normalized noise equivalent absorption NNEA = 3.75 × 10(-11) cm(-1)W/Hz(½), was achieved, representing a nearly one-order-of-magnitude improvement with respect to previous reports.

  1. Quartz-enhanced photoacoustic spectroscopy exploiting tuning fork overtone modes

    Science.gov (United States)

    Sampaolo, A.; Patimisco, P.; Dong, L.; Geras, A.; Scamarcio, G.; Starecki, T.; Tittel, F. K.; Spagnolo, V.

    2015-12-01

    We report on a quartz-enhanced photoacoustic sensor (QEPAS) based on a custom-made quartz tuning fork (QTF) to operate in both the fundamental and the first overtone vibrational mode resonances. The QTF fundamental mode resonance falls at ˜3 kHz and the first overtone at ˜18 kHz. Electrical tests showed that the first overtone provides a higher quality factor and increased piezoelectric current peak values, with respect to the fundamental flexural mode. To evaluate the QTF acousto-electric energy conversion efficiency, we operated the QEPAS in the near-IR and selected water vapor as the target gas. The first overtone resonance provides a QEPAS signal-to-noise ratio ˜5 times greater with respect to that measured for the fundamental mode. These results open the way to employing QTF overtone vibrational modes for QEPAS based trace gas sensing.

  2. Quartz tuning forks with novel geometries for optoacoustic gas sensing

    Science.gov (United States)

    Spagnolo, V.; Sampaolo, A.; Patimisco, P.; Dong, L.; Gupta, Y.; Yu, Y.; Geras, A.; Giglio, M.; Calabrese, P. P.; Starecki, T.; Scamarcio, G.; Tittel, Frank K.

    2016-02-01

    We report the successful realization of quartz-enhanced photo-acoustic (QEPAS) sensors employing quartz tuning forks (QTFs) with novel geometrical parameters. We investigated the influence of QTF sizes on the main resonator parameters, in order to identify the best design parameters optimizing the QTF figures of merit for optoacoustic gas sensing. To evaluate the QTF acousto-electric energy conversion efficiency, we operated the QEPAS sensors in the near- IR and selected water vapor as the target gas. QTFs are forced to resonate at both the fundamental and the first overtone vibrational mode frequencies. Our results shows that two QTF designs exhibit an higher quality factor (and consequently an higher QEPAS signal) when operating on the first overtone mode with respect to the fundamental one.

  3. Characterization of authigenic idiomorphous lignite and saliniferous quartz crystals by inclusion studies

    Energy Technology Data Exchange (ETDEWEB)

    Fruth, M.; Blankenburg, H.J.

    1992-12-01

    Classic microthermometry has been carried out on gas-fluid-inclusions in euhedral quartz crystals in a lignite at open cast mines Espenhain, Zwenkau and Cospuden to the south of Leipzig (called lignite quartz crystals and stub quartz crystals) and in a Stassfurt seam at the Southern Harz Potasch area (called saliniferous quartz crystals). The inclusions are classified after their shape homogenization temperatures and content of the solutions. 1. The isolated gas-fluid- and gas-fluid-solid-inclusions, with a regular shape are found in lignite quartz crystals and in saliniferous quartz crystals which probably formed in carnallitic saltrocks and kieseritic 'Hartsalz'. The inclusions of stub quartz crystals and the other saliniferous quartzes investigated are characterized by irregular thin shape. 2. By the aid of thermometry stub quartz crystals are classified into two quartz generations. The homogenization temperatures of gas-fluid-inclusions in lignite quartz crystals give a mean TH/F41[degree]C. The primary gas-fluid-inclusions of saliniferous quartz crystals can be distinguished such as: carnallitic saltrocks44[degree]C; kieseritic 'Hartsalz'76[degree]C; langbeinitic 'Hartsalz'85[degree]C; glaseritic 'Hartsalz'63[degree]C; polyhaliti 'Hartsalz'71[degree]C; anhydritic 'Hartsalz'61[degree]C; impoverishment44[degree]C. 3. Both generations of stub quartz crystals contain in their gas-fluid-inclusions NaCl-solutions. Highly saline MgCL[sub 2]-solutions were trapped in euhedral quartz crytals selected from lignite directly. The primary gas-fluid-inclusions of saliniferous quartz crystals accumulated highly saline CaCl[sub 2]/MgCl[sub 2]-solutions.

  4. Evaluation of the approach to respirable quartz exposure control in U.S. coal mines.

    Science.gov (United States)

    Joy, Gerald J

    2012-01-01

    Occupational exposure to high levels of respirable quartz can result in respiratory and other diseases in humans. The Mine Safety and Health Adminstration (MSHA) regulates exposure to respirable quartz in coal mines indirectly through reductions in the respirable coal mine dust exposure limit based on the content of quartz in the airborne respirable dust. This reduction is implemented when the quartz content of airborne respirable dust exceeds 5% by weight. The intent of this dust standard reduction is to restrict miners' exposure to respirable quartz to a time-weighted average concentration of 100 μg/m(3). The effectiveness of this indirect approach to control quartz exposure was evaluated by analyzing respirable dust samples collected by MSHA inspectors from 1995 through 2008. The performance of the current regulatory approach was found to be lacking due to the use of a variable property-quartz content in airborne dust-to establish a standard for subsequent exposures. In one situation, 11.7% (4370/37,346) of samples that were below the applicable respirable coal mine dust exposure limit exceeded 100 μg/m(3) quartz. In a second situation, 4.4% (895/20,560) of samples with 5% or less quartz content in the airborne respirable dust exceeded 100 μg/m(3) quartz. In these two situations, the samples exceeding 100 μg/m(3) quartz were not subject to any potential compliance action. Therefore, the current respirable quartz exposure control approach does not reliably maintain miner exposure below 100 μg/m(3) quartz. A separate and specific respirable quartz exposure standard may improve control of coal miners' occupational exposure to respirable quartz.

  5. Fluid inclusions in quartz crystals from South-West Africa.

    Science.gov (United States)

    Kvenvolden, K. A.; Roedder, E.

    1971-01-01

    Quartz crystals from calcite veins of unknown age in Precambrian metasedimentary rocks at Geiaus No. 6 and Aukam farms in South-West Africa contain both primary and secondary inclusions filled with one substance or a combination of substances. These substances include organic liquid, moderately saline aqueous liquid, dark-colored solid, and a vapor. Analysis of these materials by microscopy and by gas chromatography and mass spectrometry shows the presence of constituents of both low and high molecular weights.

  6. Symmetry and piezoelectricity: evaluation of α-quartz coefficients

    Science.gov (United States)

    Tannous, C.

    2017-11-01

    Piezoelectric coefficients of α-quartz are derived from symmetry arguments based on Neumann’s principle using three different methods: Fumi, Landau-Lifshitz and Royer-Dieulesaint. While the Fumi method is tedious and the Landau-Lifshitz method requires additional physical principles to evaluate the piezoelectric coefficients, the Royer-Dieulesaint method is the most elegant and most efficient of the three techniques.

  7. Ablative and mechanical properties of quartz phenolic composites

    OpenAIRE

    Maria L. Gregori; Edson A. Barros; Gilberto P. Filho; Luiz Cláudio Pardini; Sonia F. Costa

    2009-01-01

    Abstract. Quartz phenolic composites have been applied to thermal protection systems (TPSs) for reentry vehicles since the late fifties due to their excellent ablative resistance and mechanical performance. TPSs must withstand the aggressive reentry environment, such as atomic oxygen, when submitted to very high temperatures (> 1000° C) and heat flux. The ablative performance of composites is influenced by both base materiais and environmental parameters during the ablation process. For TPS s...

  8. Signatures of ESR signals and TL observed in quartz of Kizu river sediments and in host rocks

    Science.gov (United States)

    Nosohara, Y.; Toyoda, S.; Takada, M.; Shimada, A.; Masanori, Y.

    2013-12-01

    Paramagnetic lattice defects in quartz have recently been used as tracers to study the transportation of sediments on the surface of the earth especially for the origin of aeolian dust (e.g. Toyoda and Naruse, 2002), as isotopes have been used. Studies on aeolian dust have used only the E1' center while impurity centers were shown to be other useful signatures in the studies of river sediments (Shimada, 2008). Then the ESR signals of the E1' center in quartz was used to investigate the origin of the loess in MIS 1 and 2 (Toyoda and Naruse, 2002) and these diments in the Sea of Japan (Nagashima et al., 2007), Shimada (2008) showed that TLCI (thermiluminescence color image) may be useful for similar qualitative study on river sediments. In the present study, the wavelength-temperature two demensional thermoluminescence measurement was employed, together with the ESR measurements, to investigate the origin of the river sediments quantitatively. We collected 36 river sediments and 5 granites which are possible sources of the river sediments. The samples were crushed and sieved to 1000-500, 500-250, and 250-75 micrometers. Quartz grains were extracted from each size fraction by chemical treatment and density separation. The quartz grains were heated at 400°C for 1 h to erase the inherited ESR signals before gamma ray irradiation. ESR measurements were performed at room temperature and at 81 K to observe E1' and Ge, and Al and Ti centers, respectively. The impurity centers were enhanced by gamma ray irradiation. The formation efficiencies of the signals at the origin were obtained, which probably correspond to impurity concentrations in quartz. The E1' center was observed after heating the sample irradiated to 2.5kGy at 300°C for 15 min. The formation efficiencies of impurity centers and the intensity of the E1' center showed constant values in 10 samples of sediments of Muro river with standard deviations of (7-12%). It was also found that these values characterize

  9. Improved electron probe microanalysis of trace elements in quartz

    Science.gov (United States)

    Donovan, John J.; Lowers, Heather; Rusk, Brian G.

    2011-01-01

    Quartz occurs in a wide range of geologic environments throughout the Earth's crust. The concentration and distribution of trace elements in quartz provide information such as temperature and other physical conditions of formation. Trace element analyses with modern electron-probe microanalysis (EPMA) instruments can achieve 99% confidence detection of ~100 ppm with fairly minimal effort for many elements in samples of low to moderate average atomic number such as many common oxides and silicates. However, trace element measurements below 100 ppm in many materials are limited, not only by the precision of the background measurement, but also by the accuracy with which background levels are determined. A new "blank" correction algorithm has been developed and tested on both Cameca and JEOL instruments, which applies a quantitative correction to the emitted X-ray intensities during the iteration of the sample matrix correction based on a zero level (or known trace) abundance calibration standard. This iterated blank correction, when combined with improved background fit models, and an "aggregate" intensity calculation utilizing multiple spectrometer intensities in software for greater geometric efficiency, yields a detection limit of 2 to 3 ppm for Ti and 6 to 7 ppm for Al in quartz at 99% t-test confidence with similar levels for absolute accuracy.

  10. Investigation of formaldehyde interaction with carbon nanotubes and quartz sand

    Science.gov (United States)

    Georgopoulou, Maria P.; Chrysikopoulos, Constantinos V.

    2017-04-01

    Assessment of the potential impact of synthetic carbon nanotubes on the fate and transport of common chemical contaminants (pesticides, pharmaceuticals, etc.) in groundwater systems is considered to be an increasingly important aspect of environmental research. This study investigates the interaction of formaldehyde with multi-walled carbon nanotubes (MWCNTs) and quartz sand under static and dynamic conditions. Due to polarity, formaldehyde, is expected to develop strong adsorptive interactions with carbon nanotubes. Several batch adsorption experiments were conducted in test tubes, under controlled conditions. Various initial formaldehyde solution concentration (2, 5, 8 ppm), contact times, and temperatures (8, 18, 25 °C) were considered. Supernatant liquid samples were collected at regular intervals, and centrifuged. Subsequently, the formaldehyde concentration in the supernatant was quantified indirectly, by derivatization with Nash reagent and subsequent measurement of the resulting complex using spectrophotometry in the visible spectral range. Experimental results suggested that formaldehyde has a low affinity for quartz sand, but an enhanced potential for adsorption onto carbon nanotubes. Formaldehyde adsorption onto both absorbents (quartz sand and MWCNTs) was more pronounced under dynamic than static conditions, probably, because agitation improves the mixing of the absorbent within the solution. Also, it was shown that the adsorption data were adequately described by the pseudo-second order kinetic model, suggesting that the primary adsorption mechanism was chemisorption, where two or more (sequential or parallel) processes (e.g. surface chemisorption, intraparticle diffusion) were taking place. Therefore, MWCNTs could be promising adsorbent materials for groundwater remediation.

  11. Next Generation AT-Cut Quartz Crystal Sensing Devices

    Directory of Open Access Journals (Sweden)

    Vojko Matko

    2011-04-01

    Full Text Available Generally, AT-cut quartz crystals have a limited scope of use when it comes to high-precision measurement of very small impedance changes due to their nonlinear frequency-temperature characteristics in the range between 0 °C and 50 °C. The new method improving quartz oscillator frequency-temperature characteristic compensation is switching between two impedance loads. By modifying the oscillator circuit with two logic switches and two impedance loads, the oscillator can switch oscillation between two resonance frequencies. The difference in resonance frequencies compensates the frequency-temperature characteristics influence as well as the influence of offset and quartz crystal ageing. The experimental results show that the new approach using the switching method highly improves second-to-second frequency stability from ±0.125 Hz to ±0.00001 Hz and minute-to-minute frequency stability from 0.1 Hz to 0.0001 Hz, which makes the high-precision measurement of aF and fH changes possible.

  12. Next Generation AT-Cut Quartz Crystal Sensing Devices

    Science.gov (United States)

    Matko, Vojko

    2011-01-01

    Generally, AT-cut quartz crystals have a limited scope of use when it comes to high-precision measurement of very small impedance changes due to their nonlinear frequency-temperature characteristics in the range between 0 °C and 50 °C. The new method improving quartz oscillator frequency-temperature characteristic compensation is switching between two impedance loads. By modifying the oscillator circuit with two logic switches and two impedance loads, the oscillator can switch oscillation between two resonance frequencies. The difference in resonance frequencies compensates the frequency-temperature characteristics influence as well as the influence of offset and quartz crystal ageing. The experimental results show that the new approach using the switching method highly improves second-to-second frequency stability from ±0.125 Hz to ±0.00001 Hz and minute-to-minute frequency stability from 0.1 Hz to 0.0001 Hz, which makes the high-precision measurement of aF and fH changes possible. PMID:22163858

  13. Voltage-controlled narrowband and wide, variable-range four-segment quartz crystal oscillator.

    Science.gov (United States)

    Ruslan, Ruzaini; Satoh, Tomio; Akitsu, Tetsuya

    2012-03-01

    In this work, our goal is to develop a voltage-controlled variable-frequency quartz crystal oscillator with narrowband response, wide, variable frequency range and the capacity to oscillate across the series resonance frequency using a four-segment configuration of a quartz crystal oscillator. In conventional quartz oscillators, the quartz resonator is inserted in the feedback loop between the input and the output of the active circuit, providing sufficient gain and the phase relation. In the oscillator developed here, the quartz crystal resonator is inserted between the loop circuit and the ground potential. The performance of the voltage-controlled variable-frequency oscillator is demonstrated across the series resonance frequency.

  14. Alternative grains in nutrition

    Directory of Open Access Journals (Sweden)

    Jevcsák Sz.

    2016-12-01

    Full Text Available Many people suffer from gluten sensitivity or gluten intolerance. They have to avoid or limit their gluten intake. Sorghum and millet are gluten-free cereals, wherefore persons with gluten sensitivity or gluten intolerance could consume them. Moreover, they have a lot of positive effects due to their phenolic compounds as phenol acid or flavonoid. Antioxidant activity in sorghum is especially high in comparison with other cereals. Our aim was to compare literature data about the chemical compositions of sorghum and millet with other grains.

  15. Evolution of Interstellar Grains

    Science.gov (United States)

    Allamandola, Lou J.; DeVincenzi, Donald L. (Technical Monitor)

    1998-01-01

    During the past two decades observations combined with laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the raw materials from which planets, comets and stars form. Most interstellar material is concentrated in large molecular clouds where simple molecules are formed by dust-grain and gas-phase reactions. Gaseous species striking the cold (10K) dust stick, forming an icy grain mantle. This accretion, coupled with UV photolysis, produces a complex chemical mixture containing volatile, non-volatile, and isotopically fractionated species. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, H2, and perhaps some NH3 and H2CO, as well as more complex species. The evidence for these compounds, as well as carbon-rich materials, will be reviewed and the possible connections with comets and meteorites will be presented in the first part of the talk . The second part of the presentation will focus on interstellar/precometary ice photochemical evolution and the species likely to be found in comets. The chemical composition and photochemical evolution of realistic interstellar/pre-cometary ice analogs will be discussed. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and more complex molecules. When ices representative of interstellar grains and comets are exposed to UV radiation at low temperature a series of moderately complex organic molecules are formed in the ice including: CH3CH2OH (ethanol), HC(=O)NH2 (formamide), CH3C(=O)NH2 (acetamide), and R-C=N (nitriles). Several of these are already known to be in the interstellar medium, and their presence indicates the importance of grain processing. After warming to room temperature an organic residue remains. This is composed primarily of hexamethylenetetramine (HMT, C6H12N4), with lesser amounts of polyoxymethylene-related species (POMs), amides, and ketones. This is in sharp contrast to the organic residues produced by

  16. Brittle-to-viscous behaviour of quartz gouge in shear experiments

    Science.gov (United States)

    Richter, Bettina; Stunitz, Holger; Heilbronner, Renée

    2016-04-01

    In order to study the microstructure development across the brittle-viscous transition and to derive the corresponding flow laws, we performed shear experiments on quartz gouge in a Griggs-type deformation apparatus. The starting material is a crushed quartz single crystal (sieved grain size strain-rate-stepping experiments were conducted at strain rates between ˜2.5 x 10-6 s-1 and ˜2.5 x 10-4 s-1. Other experiments were conducted at constant strain rates of ˜2.5 x 10-6 s-1, ˜2.5 x 10-5 s-1, ˜2.5 x 10-4 s-1 and ˜2.5 x 10-3 s-1. At high confining pressure, the strength of the samples decreases with increasing temperature for all strain rates. The largest decrease occurred between 650 ° C and 700 ° C at shear strain rates of ˜2.5 x 10-5 s-1. At the same time, the pressure dependence of strength is positive for T ≤ 650 ° C while an inverse pressure dependence is observed at T > 650 ° C. For T strain rates of ˜2.5 x 10-5 s-1 a change in the deformation process occurs from one dominated by cataclastic flow to one dominated by crystal plasticity. The microstructure reveals a less abrupt transition in terms of operating processes, because brittle and viscous processes are equally active around 650 ° C. With increasing temperature the volume fraction of recrystallised grains increases, and at 900 ° C - 1000 ° C recrystallisation is nearly complete at strains of γ ˜ 3. The crystallographic preferred orientation of the c-axis evolves from a random distribution at low temperatures towards two peripheral maxima at intermediate temperatures. At high temperatures the c-axis show a single Y-maximum. At high temperature, the stress exponent is n = 2.1 ± 0.2. The activation energy Q is 193 ± 12 kJ/mol at strain rates of 10-5 s-1, at faster strain rates the activation energy drops down to Q = 119 ± 12 kJ/mol. This small stress exponent at high temperatures indicates a combination of deformation processes (diffusion in very fine grained material and dislocation

  17. Amorphization and Frictional Processes in Smectite-Quartz Gouge Mixtures Sheared from Sub-seismic to Seismic Slip Rates

    Science.gov (United States)

    Aretusini, S.; Mittempergher, S.; Spagnuolo, E.; Di Toro, G.; Gualtieri, A.; Plümper, O.

    2015-12-01

    Slipping zones in shallow sections of megathrusts and large landslides are often made of smectite and quartz gouge mixtures. Experiments aimed at investigating the frictional processes operating at high slip rates (>1 m/s) may unravel the mechanics of these natural phenomena. Here we present a new dataset obtained with two rotary shear apparatus (ROSA, Padua University; SHIVA, INGV-Rome). Experiments were performed at room humidity and temperature on four mixtures of smectite (Ca-Montmorillonite) and quartz with 68, 50, 25, 0 wt% of smectite. The gouges were slid for 3 m at normal stress of 5 MPa and slip rate V from 300 µm/s to 1.5 m/s. Temperature during the experiments was monitored with four thermocouples and modeled with COMSOL Multiphysics. In smectite-rich mixtures, the friction coefficient µ evolved with slip according to three slip rate regimes: in regime 1 (V0.3 m/s) µ had strong slip-weakening behavior. Instead, in quartz-rich mixtures the gouge had a monotonic slip-weakening behavior, independently of V. Temperature modelling showed that the fraction of work rate converted into heat decreased with increasing smectite content and slip rate. Quantitative X-ray powder diffraction (Rietveld method) indicates that the production of amorphous material from smectite breakdown increased with frictional work but was independent of work rate. Scanning Electron Microscopy investigation evidenced strain localization and presence of dehydrated clays for V≥0.3 m/s; instead, for Vfrictional weakening. Instead, slip-weakening was concomitant to strain localization and possible vaporization of water adsorbed on smectite grain surfaces.

  18. Gamma radiation-induced thermoluminescence, trace element and paramagnetic defect of quartz from the Sambagawa metamorphic belt, Central Shikoku, Japan.

    Science.gov (United States)

    Chuenpee, T; Nishikawa, O; Kon, Y; Ninagawa, K; Toyoda, S; Ogata, T; Uchida, T; Takashima, I

    2017-02-01

    This study analyzes the Thermoluminescence (TL) emissions for five emission bands, trace element concentrations and defects in quartz grains extracted from metamorphic rocks and quartz veins in the Sambagawa metamorphic belt, central Shikoku. An emission of 500nm with 195, 245, and 320-325°C glow peaks are observed through the lowest to highest grade samples. A 450nm emission band with intense 195 and 245°C glow peaks and a 320-325°C shoulder peak is found in the higher grade samples. A 570nm emission band with a 170°C glow peak is observed in the samples derived from the lower grade zones. These characteristics of TL emissions of quartz suggest that they can be an indicator for the identification of rock derived from different metamorphic grades. The higher metamorphic grade samples with 450nm emission bands in particular show higher intensities of the E1' center. This relation indicates that the activation of the E1' center in higher metamorphic conditions possibly contributed to the 450nm emission band. Also, the 500nm emission band is generally observed in the samples with the signal intensities of the Aluminum hole center, suggesting that the center is the source of this emission band. We also observed that the lower metamorphic grade samples contain lower signal intensities of the Aluminum hole center, despite higher aluminum concentrations. This inconsistency indicates that the formation of interstitial aluminum ions cause local lattice distortion regions, where self-trapped excitons can be formed and presumably provide the 570nm emissions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Carbon in intimate contact with quartz reduces the biological activity of crystalline silica dusts.

    Science.gov (United States)

    Ghiazza, Mara; Tomatis, Maura; Doublier, Sophie; Grendene, Francesca; Gazzano, Elena; Ghigo, Dario; Fubini, Bice

    2013-01-18

    To evaluate the effect of carbonaceous materials on the pathogenic activity of quartz dusts, mixtures of carbon soot (1 and 10%) and quartz (Min-U-Sil) were prepared and then milled so to attain an intimate association of carbon and the quartz surface. Both cellular and cell-free tests show that carbon associated to quartz completely inhibits the typical free radical generation of quartz dusts (through Fenton activity and homolytic cleavage of a C-H bond) and suppresses the oxidative stress and inflammation induced by quartz alone on MH-S murine macrophage cells (lipid peroxidation, nitric oxide release, and tumor necrosis factor-α synthesis). The cytotoxic response to quartz is also largely reduced. An extremely pure quartz milled with 10% of soot showed inactivating effects on the adverse reactions to quartz similar to Min-U-Sil quartz. None of these effects takes place when the same experiments are carried out with mechanically mixed samples, which suggests that carbon acts not just as a radical quencher but because of its association to the quartz surface.

  20. Water weakening during semibrittle flow and faulting of experimentally deformed quartz sandstone

    Science.gov (United States)

    Kanaya, T.; Hirth, G.

    2015-12-01

    Triaxial compression experiments were conducted on Fontainebleau sandstone at temperatures to 900°C and effective pressures to 175 MPa with varying water contents. Both yield and peak strengths associated with semibrittle faulting decrease linearly with an increase in intragranular water concentration (COH); COH is determined from infrared spectroscopy. Microstructural observations and the influence of strain rate, temperature, and COH on peak strength suggest that transient semibrittle flow is accommodated through cataclasis assisted by stress-corrosion microcracking. The roles of the experimental variables on the constitutive behavior are similar to those reported for subcritical cracking of quartz single crystals. At high COH, microstructural observations indicate an increase in the relative contribution of mm-scale distributed shear fractures (bands) to axial strain, reflecting a reduction in grain-scale fracture toughness. This is consistent with the inference that highly dissipative shear fractures lead to the observed reduction in strength at high COH. Stress vs. strain rate data for transient semibrittle flow show temperature-dependent rate behavior, and are well fit by an exponential law with an activation enthalpy of 185 to 250 kJ/mol and Peierls stress of 2.5 to 7.5 GPa. Using these constraints, we infer that stress-corrosion cracking is rate-limited by the dislocation activity at crack tips. Correlation of microscale COH maps to microstructures suggests that intragranular water in the undeformed sandstone is associated mainly with clusters of fluid inclusions, resulting in a highly nonuniform distribution of COH both within and between grains. Axially deformed samples show a reduction in the median and variability of COH over a range of length scales. We observe that a local reduction in COH correlates with fluid inclusions that are decrepitated and crosscut by intragranular fractures. We conclude that intragranular fracture is the primary mechanism of

  1. Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions

    Science.gov (United States)

    Padmanabhan, Sharmila; Fung, King Man; Kangaslahti, Pekka P.; Peralta, Alejandro; Soria, Mary M.; Pukala, David M.; Sin, Seth; Samoska, Lorene A.; Sarkozy, Stephen; Lai, Richard

    2012-01-01

    Packaging of MMIC LNA (monolithic microwave integrated circuit low-noise amplifier) chips at frequencies over 200 GHz has always been problematic due to the high loss in the transition between the MMIC chip and the waveguide medium in which the chip will typically be used. In addition, above 200 GHz, wire-bond inductance between the LNA and the waveguide can severely limit the RF matching and bandwidth of the final waveguide amplifier module. This work resulted in the development of a low-loss quartz waveguide transition that includes a capacitive transmission line between the MMIC and the waveguide probe element. This capacitive transmission line tunes out the wirebond inductance (where the wire-bond is required to bond between the MMIC and the probe element). This inductance can severely limit the RF matching and bandwidth of the final waveguide amplifier module. The amplifier module consists of a quartz E-plane waveguide probe transition, a short capacitive tuning element, a short wire-bond to the MMIC, and the MMIC LNA. The output structure is similar, with a short wire-bond at the output of the MMIC, a quartz E-plane waveguide probe transition, and the output waveguide. The quartz probe element is made of 3-mil quartz, which is the thinnest commercially available material. The waveguide band used is WR4, from 170 to 260 GHz. This new transition and block design is an improvement over prior art because it provides for better RF matching, and will likely yield lower loss and better noise figure. The development of high-performance, low-noise amplifiers in the 180-to- 700-GHz range has applications for future earth science and planetary instruments with low power and volume, and astrophysics array instruments for molecular spectroscopy. This frequency band, while suitable for homeland security and commercial applications (such as millimeter-wave imaging, hidden weapons detection, crowd scanning, airport security, and communications), also has applications to

  2. Intermittent loading of teeth restored using quartz fiber, carbon-quartz fiber, and zirconium dioxide ceramic root canal posts.

    Science.gov (United States)

    Mannocci, F; Ferrari, M; Watson, T F

    1999-01-01

    The purpose of the investigation was to compare the performances of teeth restored with quartz fiber, carbon-quartz fiber, and zirconium-dioxide posts covered with all-ceramic crowns when subjected to a cyclic loading test performed in a wet environment. Forty single-rooted human lower premolars having similar dimensions were endodontically treated and mounted in acrylic resin blocks with a simulated periodontal ligament. The teeth were divided into three experimental groups and one control group. Post holes 8 mm long were prepared in the roots of the experimental groups in which quartz fiber, carbon-quartz fiber, and zirconium dioxide posts were cemented. In the control group, no posts were used. The crown buildup was made with composite resin. The teeth were covered with all-ceramic crowns and intermittently loaded at an angle of 45 degrees to the long axis of the tooth at a frequency of two loads per second. Only one failure (root fracture + post fracture) was observed in each of the fiber post groups, while in the zirconium dioxide post group, six failures were observed (one crown fracture and 5 root fractures + post fractures). The Kaplan-Meier analysis of the three experimental groups showed that the survival rate of zirconium dioxide posts was significantly lower than that of both types of fiber post. All the experimental groups showed a survival rate higher than that of the control group. Fiber posts reduced to a minimum the risk of root fractures of teeth restored with composite cores and Empress crowns under the present experimental conditions (intermittent loading in a wet environment).

  3. Reconstruction of 3d grain boundaries from rock thin sections, using polarised light

    Science.gov (United States)

    Markus Hammes, Daniel; Peternell, Mark

    2016-04-01

    Grain boundaries affect the physical and chemical properties of polycrystalline materials significantly by initiating reactions and collecting impurities (Birchenall, 1959), and play an essential role in recrystallization (Doherty et al. 1997). In particular, the shape and crystallographic orientation of grain boundaries reveal the deformation and annealing history of rocks (Kruhl and Peternell 2002, Kuntcheva et al. 2006). However, there is a lack of non-destructive and easy-to-use computer supported methods to determine grain boundary geometries in 3D. The only available instrument using optical light to measure grain boundary angles is still the polarising microscope with attached universal stage; operated manually and time-consuming in use. Here we present a new approach to determine 3d grain boundary orientations from 2D rock thin sections. The data is recorded by using an automatic fabric analyser microscope (Peternell et al., 2010). Due to its unique arrangement of 9 light directions the highest birefringence colour due to each light direction and crystal orientation (retardation) can be determined at each pixel in the field of view. Retardation profiles across grain boundaries enable the calculation of grain boundary angle and direction. The data for all positions separating the grains are combined and further processed. In combination with the lateral position of the grain boundary, acquired using the FAME software (Hammes and Peternell, in review), the data is used to reconstruct a 3d grain boundary model. The processing of data is almost fully automatic by using MATLAB®. Only minor manual input is required. The applicability was demonstrated on quartzite samples, but the method is not solely restricted on quartz grains and other birefringent polycrystalline materials could be used instead. References: Birchenall, C.E., 1959: Physical Metallurgy. McGraw-Hill, New York. Doherty, R.D., Hughes, D.A., Humphreys, F.J., Jonas, J.J., Juul Jensen, D., Kassner, M

  4. Evolution of the volcanic plumbing systemof Alicudi (Aeolian Islands - Italy: evidence from fluid and melt inclusionsin quartz xenoliths

    Directory of Open Access Journals (Sweden)

    A. Peccerillo

    2004-06-01

    Full Text Available Quartz-rich xenoliths in lavas (basalts to andesites; 90-30 ka from Alicudi contain abundant melt and fluid inclusions. Two generations of CO2-rich fluid inclusions are present in quartz-rich xenolith grains: early (Type I inclusions related to partial melting of the host xenoliths, and late Type II inclusions related to the fluid trapping during xenolith ascent. Homogenisation temperatures of fluid inclusions correspond to two density intervals: 0.93-0.68 g/cm3 (Type I and 0.47-0.26 g/cm3 (Type II. Early Type I fluid inclusions indicate trapping pressures around 6 kbar, which are representative for the levels of partial melting of crustal rocks and xenolith formation. Late Type II fluid inclusions show lower trapping pressures, between 1.7 kbar and 0.2 kbar, indicative for shallow magma rest and accumulation during ascent to the surface. Data suggest the presence of two magma reservoirs: the first is located at lower crustal depths (about 24 km, site of fractional crystallization, mixing with source derived magma, and various degrees of crustal assimilation. The second magma reservoir is located at shallow crustal depths (about 6 km, the site where magma rested for a short time before erupting.

  5. Infrared measurement of undercooling during silicon solidification on bare and Si3N4 coated quartz substrates

    Science.gov (United States)

    Yang, C. F.; Tsoutsouva, M. G.; Hsu, H. P.; Lan, C. W.

    2016-11-01

    Undercooling is one of the most significant parameters in the solidification of silicon since it controls the grain structure formation, which determines the final performance of solar cell. Here a new and simple experimental facility is proposed to provide reliable undercooling values and visualize the melting-solidification process when silicon solidifies on a bare and a Si3N4 coated quartz (SiO2) substrate. A lamp heating system was used for the melting, the undercooling temperature was measured with the aid of an infrared single-color pyrometer while the morphologies of the growing silicon on the SiO2 and Si3N4-coated SiO2 substrates are also investigated through a digital microscope. The high precision and accuracy of the given undercooling values when using the present setup comes from the principle of minimizing the background radiation that can significantly influence the pyrometer measurements.

  6. Label-Free Detection of Gliadin in Food by Quartz Crystal Microbalance-Based Immunosensor.

    Science.gov (United States)

    Funari, Riccardo; Terracciano, Irma; Della Ventura, Bartolomeo; Ricci, Sara; Cardi, Teodoro; D'Agostino, Nunzio; Velotta, Raffaele

    2017-02-15

    Gluten is a protein composite found in wheat and related grains including barley, rye, oat, and all their species and hybrids. Gluten matrix is a biomolecular network of gliadins and glutenins that contribute to the texture of pastries, breads, and pasta. Gliadins are mainly responsible for celiac disease, one of the most widespread food-related pathologies in Western world. In view of the importance of gliadin proteins, by combining the quartz crystal microbalance technology, a cheap and robust piezoelectric transducer, with the so-called photonic immobilization technique, an effective surface functionalization method that provides spatially oriented antibodies on gold substrates, we realized a sensitive and reliable biosensor for quantifying these analytes extracted from real samples in a very short time. The resulting immunosensor has a limit of detection of about 4 ppm and, more remarkably, shows excellent sensitivity in the range 7.5-15 ppm. This feature makes our device reliable and effective for practical applications since it is able to keep low the influence of false positives.

  7. Optical properties of PLT films with various composition on quartz and modifications of their surfaces

    CERN Document Server

    Yoon, Y S; Koh, S K; Jung, H J

    1999-01-01

    (Pb sub 1 sub - sub x La sub x)TiO sub 3 (PLT) films with various compositions of La were deposited by using the sol-gel process on quartz substrates in order to study their optical properties. X-ray patterns indicated that the pseudocubic phase of the PLT film dominated with increased La concentration due to a decrease in the lattice constant of the c-axis. Three-dimensional atomic force microscopy images revealed that the grain size and root mean square (r.m.s) surface roughness were decreased by adding of La. The optical band gap of the as-deposited films became wider when Pb was replaced with La, which could be calculated from the transmittance of an UV-visible spectrometer. The addition of La increased the transparency of the PbTiO sub 3 film and shifted the threshold to shorter wavelengths for initiation of absorption. In addition, we modified the surfaces of the PLT films with La concentrations of 5 % by using an oxygen-ion beam with an oxygen-ion energy of 1 kV at different doses. The optical band gap...

  8. Reaction-induced grain boundary cracking and anisotropic fluid flow during prograde devolatilization reactions within subduction zones

    Science.gov (United States)

    Okamoto, Atsushi; Shimizu, Hiroyuki; Fukuda, Jun-ichi; Muto, Jun; Okudaira, Takamoto

    2017-09-01

    Devolatilization reactions during prograde metamorphism are a key control on the fluid distribution within subduction zones. Garnets in Mn-rich quartz schist within the Sanbagawa metamorphic belt of Japan are characterized by skeletal structures containing abundant quartz inclusions. Each quartz inclusion was angular-shaped, and showed random crystallographic orientations, suggesting that these quartz inclusions were trapped via grain boundary cracking during garnet growth. Such skeletal garnet within the quartz schist formed related to decarbonation reactions with a positive total volume change (Δ V t > 0), whereas the euhedral garnet within the pelitic schists formed as a result of dehydration reaction with negative Δ V t values. Coupled hydrological-chemical-mechanical processes during metamorphic devolatilization reactions were investigated by a distinct element method (DEM) numerical simulation on a foliated rock that contained reactive minerals and non-reactive matrix minerals. Negative Δ V t reactions cause a decrease in fluid pressure and do not produce fractures within the matrix. In contrast, a fluid pressure increase by positive Δ V t reactions results in hydrofracturing of the matrix. This fracturing preferentially occurs along grain boundaries and causes episodic fluid pulses associated with the development of the fracture network. The precipitation of garnet within grain boundary fractures could explain the formation of the skeletal garnet. Our DEM model also suggests a strong influence of reaction-induced fracturing on anisotropic fluid flow, meaning that dominant fluid flow directions could easily change in response to changes in stress configuration and the magnitude of differential stress during prograde metamorphism within a subduction zone.

  9. Relative Shock Effects in Mixed Powders of Calcite, Gypsum, and Quartz: A Calibration Scheme from Shock Experiments

    Science.gov (United States)

    Bell, Mary S.

    2009-01-01

    The shock behavior of calcite and gypsum is important in understanding the Cretaceous/Tertiary event and other terrestrial impacts that contain evaporite sediments in their targets. Most interest focuses on issues of devolatilization to quantify the production of CO2 or SO2 to better understand their role in generating a temporary atmosphere and its effects on climate and biota [e.g., papers in 1,2,3,4]. Devolatilization of carbonate is also important because the dispersion and fragmentation of ejecta is strongly controlled by the expansion of large volumes of gas during the impact process as well [5,6]. Shock recovery experiments for calcite yield seemingly conflicting results: early experimental devolatilization studies [7,8,9] suggested that calcite was substantially outgassed at 30 GPa (> 50%). However, the recent petrographic work of [10,11,12] presented evidence that essentially intact calcite is recovered from 60 GPa experiments. [13] reported results of shock experiments on anhydrite, gypsum, and mixtures of those phases with silica. Their observations indicate little or no devolatilization of anhydrite shocked to 42 GPa and that the fraction of sulfur, by mass, that degassed is approx.10(exp -2) of theoretical prediction. In another (preliminary) report of shock experiments on calcite, anhydrite, and gypsum, [14] observe calcite recrystallization when shock loaded at 61 GPa, only intensive plastic deformation in anhydrite shock loaded at 63 GPa, and gypsum converted to anhydrite when shock loaded at 56 GPa. [15] shock loaded anhydrite and quartz to a peak pressure of 60 GPa. All of the quartz grains were trans-formed to glass and the platy anhydrite grains were completely pseudomorphed by small crystallized anhydrite grains. However, no evidence of interaction between the two phases could be observed and they suggest that recrystallization of anhydrite grains is the result of a solid state transformation. [16] reanalyzed the calcite and anhydrite shock

  10. Experimental investigation of suspended particles transport through porous media: particle and grain size effect.

    Science.gov (United States)

    Liu, Quansheng; Cui, Xianze; Zhang, Chengyuan; Huang, Shibing

    2016-01-01

    Particle and grain size may influence the transportation and deposition characteristics of particles within pollutant transport and within granular filters that are typically used in wastewater treatment. We conducted two-dimensional sandbox experiments using quartz powder as the particles and quartz sand as the porous medium to study the response of transportation and deposition formation to changes in particle diameter (ds, with median diameter 18, 41, and 82 μm) and grain diameter (dp, with median diameter 0.36, 1.25, and 2.82 mm) considering a wide range of diameter ratios (ds/dp) from 0.0064 to 0.228. Particles were suspended in deionized water, and quartz sand was used as the porous medium, which was meticulously cleaned to minimize any physicochemical and impurities effects that could result in indeterminate results. After the experiments, the particle concentration of the effluent and particle mass per gram of dry sands were measured to explore changes in transportation and deposition characteristics under different conditions. In addition, a micro-analysis was conducted to better analyse the results on a mesoscopic scale. The experimental observation analyses indicate that different diameter ratios (ds/dp) may lead to different deposit formations. As ds/dp increased, the deposit formation changed from 'Random Deposition Type' to 'Gradient Deposition Type', and eventually became 'Inlet Deposition Type'.

  11. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  12. Quartz dustiness: A key factor in controlling exposure to crystalline silica in the workplace.

    Science.gov (United States)

    López-Lilao, A; Escrig, A; Orts, M J; Mallol, Gustavo; Monfort, E

    2016-11-01

    The classification of Respirable Crystalline Silica (RCS) as carcinogenic for humans has drawn greater attention to crystalline silica exposure in the workplace in recent years, leading to recommendations by safety and health bodies in Europe and the U.S. for lower occupational exposure limits. In view of this new scenario, the present study examined quartz dustiness, as quartz handling is a major source of crystalline silica in the workplace. The study was conducted on test samples with different mean particle sizes, prepared from several commercial quartzes. The quartz particle samples were characterised and the influence of certain quartz particle parameters on quartz dustiness was determined. The results indicate that quartz dustiness may be significantly affected by mean particle size, specific surface area, the Hausner ratio, and fine particle content. The study shows that, in order to minimise the adverse health effects associated with the inhalation of crystalline silica, quartz dustiness may be deemed a key factor in controlling the generation of fugitive quartz emissions during quartz processing, both into the outside atmosphere (air pollution) and inside the facilities (occupational health).

  13. The adsorption of methyl methacrylate and vinyl acetate polymers on α-quartz surface: A molecular dynamics study

    Science.gov (United States)

    Yan, Lijing; Yang, Yan; Jiang, Hui; Zhang, Bingjian; Zhang, Hui

    2016-01-01

    The molecular dynamics simulation was used to investigate the adsorption of polymethyl methacrylate (PMMA) and polyvinyl acetate (PVA), the commonly used surface coating materials, on α-quartz surface. The objective is to understand the interactions between quartz surface and polymers. The results clearly show adsorption of both polymers onto the quartz surface. Carbonyl group plays a significant role in the adsorption process. The adsorption energies of PMMA and PVA on α-quartz surface did not show significant difference, however, more hydrogen bonds were observed on the PVA/quartz system than PMMA/quartz. These observations might offer some insights on the polymer-quartz adhesion and its failure mechanism.

  14. Thermal dependence of luminescence lifetimes and radioluminescence in quartz

    Energy Technology Data Exchange (ETDEWEB)

    Pagonis, V., E-mail: vpagonis@mcdaniel.edu [McDaniel College, Physics Department, Westminster, MD 21157 (United States); Chithambo, M.L. [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa); Chen, R. [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Chruścińska, A. [Institute of Physics, Nicholas Copernicus University, 87-100 Toruń (Poland); Fasoli, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Li, S.H. [Department of Earth Sciences, The University of Hong Kong (Hong Kong); Martini, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Ramseyer, K. [Institut für Geologie, Baltzerstrasse 1-3, 3012 Bern (Switzerland)

    2014-01-15

    During time-resolved optical stimulation experiments (TR-OSL), one uses short light pulses to separate the stimulation and emission of luminescence in time. Experimental TR-OSL results show that the luminescence lifetime in quartz of sedimentary origin is independent of annealing temperature below 500 °C, but decreases monotonically thereafter. These results have been interpreted previously empirically on the basis of the existence of two separate luminescence centers L{sub H} and L{sub L} in quartz, each with its own distinct luminescence lifetime. Additional experimental evidence also supports the presence of a non-luminescent hole reservoir R, which plays a critical role in the predose effect in this material. This paper extends a recently published analytical model for thermal quenching in quartz, to include the two luminescence centers L{sub H} and L{sub L}, as well as the hole reservoir R. The new extended model involves localized electronic transitions between energy states within the two luminescence centers, and is described by a system of differential equations based on the Mott–Seitz mechanism of thermal quenching. It is shown that by using simplifying physical assumptions, one can obtain analytical solutions for the intensity of the light during a TR-OSL experiment carried out with previously annealed samples. These analytical expressions are found to be in good agreement with the numerical solutions of the equations. The results from the model are shown to be in quantitative agreement with published experimental data for commercially available quartz samples. Specifically the model describes the variation of the luminescence lifetimes with (a) annealing temperatures between room temperature and 900 °C, and (b) with stimulation temperatures between 20 and 200 °C. This paper also reports new radioluminescence (RL) measurements carried out using the same commercially available quartz samples. Gaussian deconvolution of the RL emission spectra was

  15. PESTICIDES USE AMONG GRAIN MERCHANTS IN MUBI GRAIN ...

    African Journals Online (AJOL)

    AGROSEARCH UIL

    ABSTRACT. Food security in sub-Saharan Africa largely depends upon improved food productivity through the use of sustainable agricultural practices and the reduction of post-harvest losses caused by pests and diseases. This study was conducted in two major grain markets in Mubi to study pest control practices by grain ...

  16. Grain-filling, chlorophyll content in relation with grain yield ...

    African Journals Online (AJOL)

    The beginning of active phase of grain filling corresponded to the beginning of the degradation of chlorophyll content. The velocity of grain filling was negatively correlated to the number of days to heading (DH). Changes in photosynthesis most closely paralleled changes in chlorophyll content. All these changes occurred ...

  17. Substituting maize grain with barley grain in concentrates fed to ...

    African Journals Online (AJOL)

    The aim of the study was to determine the effect of substituting maize grain with barley grain in the diet of lactating Jersey cows grazing kikuyu-ryegrass pasture. Sixty Jersey cows were blocked in terms of number of days in milk, lactation number, milk yield and live weight and randomly assigned to one of five treatments (n ...

  18. Modelling of grain refinement driven by negative grain boundary energy

    Czech Academy of Sciences Publication Activity Database

    Fischer, F. D.; Zickler, G. A.; Svoboda, Jiří

    2017-01-01

    Roč. 97, č. 23 (2017), s. 1963-1977 ISSN 1478-6435 R&D Projects: GA ČR(CZ) GA15-06390S Institutional support: RVO:68081723 Keywords : grain refinement * grain nucleation * distribution concept * jump on distribution function Subject RIV: BJ - Thermodynamics Impact factor: 1.505, year: 2016

  19. Ablative and mechanical properties of quartz phenolic composites

    Directory of Open Access Journals (Sweden)

    Maria L. Gregori

    2009-01-01

    Full Text Available Quartz phenolic composites have been applied to thermal protection systems (TPSs for reentry vehicles since the late fifties due to their excellent ablative resistance and mechanical performance. TPSs must withstand the aggressive reentry environment, such as atomic oxygen, when submitted to very high temperatures (> 1000° C and heat flux. The ablative performance ofcomposites is influenced by both base materials and environmental parameters during the ablation process. For TPS systems phenolic resin is usually used as the base matrix due to its ability to form a stable char during decomposition. This char plays an important role in the absorption of the heat generated during the ablation process. During re-entry, parts of the charred matrix can be abrasively removed by shear force due to high pressure and velocity. In this work the ablative and mechanical properties of quartz phenolic composites were evaluated in order to identify the range of properties suitable for the use of these materials as thermal protection systems for space vehicles. Quartz fabric having an areal weight of 680 g/m2 and a resole-type phenolic resin were used to prepare the composites. The resin has a viscosity of 165 MPa at 20°C. The prepreg material was cured by heating under pressure of 100 bar in a mold. The resin content of the prepreg obtained was about 50 per cent. The mechanical properties evaluated were, tensile, shear and flexural strength. The results obtained showed that this material has average values of 38.5 MPa, 52 MPa and 85 MPa for tensile, shear and flexural strength, respectively. The ablative tests were carried out in a high-energy air plasma in ambient atmosphere and the mass losses were measured for different exposure time.

  20. Current Rectification with Poly-l-Lysine-Coated Quartz Nanopipettes

    Science.gov (United States)

    Umehara, Senkei; Pourmand, Nader; Webb, Chris D.; Davis, Ronald W.; Yasuda, Kenji; Karhanek, Miloslav

    2010-01-01

    Ion current rectification with quartz nanopipette electrodes was investigated through the control of the surface charge. The presence and absence of a positively charged poly-l-lysine (PLL) coating resulted in the rectified current with opposite polarity. The results agreed with the theories developed for current-rectifying conical nanopores, suggesting the similar underlying mechanism among asymmetric nanostructure in general. This surface condition dependence can be used as the fundamental principle of multi-purpose real-time in vivo biosensors. PMID:17090078

  1. Quartz Crystal Microbalance Operation and In Situ Calibration

    Science.gov (United States)

    Albyn, K. C.

    2004-01-01

    Quartz crystal microbalances (QCMs) are commonly used to measure the rate of deposition of molecular species on a surface. The measurement is often used to select materials with a low outgassing rate for applications where the material has a line of sight to a contamination-sensitive surface. A quantitative, in situ calibration of the balance, or balances, using a pure material for which the enthalpy of sublimation is known, is described in this Technical Memorandum. Supporting calculations for surface dwell times of deposited materials and the effusion cell Clausing factor are presented along with examples of multiple QCM measurements of outgassing from a common source.

  2. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    OpenAIRE

    Yongning Liu; Jun Chang; Jie Lian; Zhaojun Liu; Qiang Wang; Zengguang Qin

    2016-01-01

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 co...

  3. Off-beam quartz-enhanced photoacoustic spectroscopy.

    Science.gov (United States)

    Liu, Kun; Guo, Xiaoyong; Yi, Hongming; Chen, Weidong; Zhang, Weijun; Gao, Xiaoming

    2009-05-15

    An off-beam (OB) detection approach is suggested and experimentally investigated and optimized for quartz-enhanced photoacoustic spectroscopy (QEPAS). This OB-QEPAS configuration, very simple in assembly, not only allows for use of larger excitation optical beams and facilitating optical alignment but also provides higher enhancement of photoacoustic signals than previously published results based on the common on-beam QEPAS under the same experimental conditions. A normalized noise equivalent absorption coefficient (1sigma) of 5.9 x 10(-9) cm(-1)W/Hz(1/2) was obtained for water vapor detection at normal atmospheric pressure.

  4. Quartz enhanced photoacoustic leak sensor for mechatronic components

    Science.gov (United States)

    Sampaolo, A.; Patimisco, P.; Giglio, M.; Calabrese, P. P.; Chieco, L.; Scamarcio, G.; Tittel, F. K.; Spagnolo, V.

    2016-02-01

    We report the first demonstration of a leak sensor based on a mid-IR quartz-enhanced photoacoustic (QEPAS) spectroscopic technique. A QEPAS sensor was integrated in a vacuum seal test station for mechatronic components. The laser source is a quantum cascade laser emitting at 10.56 μm, resonant with a strong absorption band of sulfur hexafluoride (SF6), which was selected as target gas for leak detection. The minimum detectable concentration of the QEPAS sensor is 6.9 ppb with an integration time of 1 s. This detection sensitivity allowed to measure SF6 leak flows as low as 3x10-5 standard cm3.

  5. Testing the use of OSL from quartz grains for dating debris flows in Miyun, northeast Beijing, China

    DEFF Research Database (Denmark)

    Zhao, Qiuyue; Thomsen, Kristina Jørkov; Murray, Andrew

    2015-01-01

    Extreme seasonal summer rain storms are common in the mountains to the north east of Beijing and these often result in mass movement of sediment slurries transported for up to a few km. These debris flows can be deadly and are very destructive to infrastructure and agriculture. This project tests...... the application of luminescence dating to determining the return frequency of such extreme events. The high sediment concentration and the very short flow duration gives very little opportunity for daylight resetting during transport and only a small fraction of the total mass is likely to be reset before...

  6. Dating recent floodplain sediments in the Hawkesbury-Nepean River system, eastern Australia using single-grain quartz OSL

    DEFF Research Database (Denmark)

    Sim, Anna K.; Thomsen, Kristina Jørkov; Murray, K.J.

    2014-01-01

    Two fluvial sediment cores taken from a floodplain of the Hawkesbury-Nepean River system in the Sydney region, eastern Australia are dated using Optically Stimulated Luminescence (OSL) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14C...

  7. Variation with depth of dose distributions in single grains of quartz extracted from an irradiated concrete block

    DEFF Research Database (Denmark)

    Thomsen, Kristina Jørkov; Jain, M.; Bøtter-Jensen, L.

    2003-01-01

    Most attempts to apply retrospective dosimetry using luminescence methods to building materials have made use of heated (sensitised) items such as brick or tile ceramic. Unfired materials, such as mortar and concrete, are much more widespread in the industrial environment, but unfortunately...

  8. The Antinutritional Components of Grains

    DEFF Research Database (Denmark)

    Madsen, Claus Krogh; Brinch-Pedersen, Henrik

    2016-01-01

    Grains provide humans and farmed animals with a very large proportion of the energy and macro- and micronutrients they need. Unfortunately, grains also contain compounds that interfere with the utilization of the nutrients by animals. These so-called antinutritionals may result in poor resource u...

  9. Asphaltene adsorption on quartz sand in the presence of pre-adsorbed water.

    Science.gov (United States)

    Gonzalez, Valeska; Taylor, Spencer E

    2016-10-15

    In the oil industry, asphaltenes are known for their tendency to aggregate in solution and to deposit on surfaces, with both properties being connected with operational problems associated with recovery, production and refining. Interactions involving asphaltenes and other crude oil components have been a major aspect of investigation in attempting to understand the full nature of these problems. Water is implicated in asphaltene behavior in solution, for example, where it has been found to delay the deposition of asphaltene aggregates. At interfaces, there is evidence that water-in-crude oil emulsion stability is enhanced through asphaltene-water interactions, and there have been a few reports that asphaltene adsorption on mineral surfaces is reduced in the presence of water. We consider the latter aspect, because the instances of reduced adsorption to date have not attempted to quantify the effect. Previous studies showed that vapor-phase adsorption of organic molecules is reduced in the presence of pre-adsorbed water and we were interested to determine whether the same is true for liquid-phase adsorption of asphaltenes. The surface of quartz sand was controlled by pre-adsorption of water from different relative humidity (RH) environments as the water adsorption isotherm is known from previous studies. These pre-conditioned sand samples were used as substrates for the adsorption from toluene solutions of n-heptane-precipitated asphaltenes (C7A) from an Athabasca oil sands bitumen. To supplement the adsorption behavior, atomic force microscopy (AFM) images were taken of the resultant sand grains at 0 and 80% RH, and low-field NMR was used to estimate the sand wettability. Asphaltene adsorption on sand is sensitive to surface-adsorbed water, with ∼4-fold reduction in adsorption when increasing the RH from 0 to 100%. This is in general agreement with previous vapor-phase adsorption of small organic molecules, and is therefore believed to be the first demonstration

  10. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important...... the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order...... for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents...

  11. Changes in OSL properties of quartz by preheating: an interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Vartanian, E. E-mail: crpaa@montaigne.u-bordeaux.fr; Guibert, P.; Roque, C.; Bechtel, F.; Schvoerer, M

    2000-12-15

    A study of OSL variation with preheat temperature showed, in a majority of cases, that OSL recorded at room temperature, increases above 200 deg. C before the normal drainage at higher temperature. To explain this behaviour, an alternative interpretation to the common 'electronic thermal transfer' mechanism is suggested, supported by a study of hydrothermally grown quartz crystals. This interpretation involves impurities in substitution of Si{sup 4+}, specially Al{sup 3+}, which are associated with species like, in the case of quartz, hydrogen (H{sup +}, in fact, OH{sup -}) and alkali ions (Li{sup +}, Na{sup +}, K{sup +}). These monovalent ions usually act as charge compensators and are mobile during heating. As a consequence of the mobility and a possible irreversible exchange between compensators, the number of radiative recombination centres associated with the OSL trap(s), observable within the detection spectral window used (250-400 nm), increases during preheating. This phenomenon could lead to a wrong ED determination.

  12. Infrared optical properties of $\\alpha$ quartz by molecular dynamics simulations

    CERN Document Server

    Gangemi, Fabrizio; Carati, Andrea; Maiocchi, Alberto; Galgani, Luigi

    2016-01-01

    This paper is concerned with theoretical estimates of the refractive--index curves for quartz, obtained by the Kubo formul\\ae\\ in the classical approximation, through MD simulations for the motions of the ions. Two objectives are considered. The first one is to understand the role of nonlinearities in situations where they are very large, as at the $\\alpha$--$\\beta$ structural phase transition. We show that on the one hand they don't play an essential role in connection with the form of the spectra in the infrared. On the other hand they play an essential role in introducing a chaoticity which involves a definite normal mode. This might explain why that mode is Raman active in the $\\alpha$ phase, but not in the $\\beta$ phase. The second objective concerns whether it is possible in a microscopic model to obtain normal mode frequencies, or peak frequencies in the optical spectra, that are in good agreement with the experimental data for quartz. Notwithstanding a lot of effort, we were unable to find results agr...

  13. Study of the bending modes in circular quartz resonators.

    Science.gov (United States)

    Leclaire, Philippe; Goossens, Jozefien; Martinez, Loïc; Wilkie-Chancelier, Nicolas; Serfaty, Stéphane; Glorieux, Christ

    2006-10-01

    An experimental and theoretical study of bending modes in a partially electroded circular piezoelectric quartz (AT-cut) with free edge is presented. The quartz is excited by a voltage pulse applied on the electrodes, and its surface is scanned by a laser vibrometer that measures the out-of-plane displacements. The classical theory of bending of thin disks is used to describe the flexural modes at frequencies lower than the first thickness shear resonance (6 MHz). A fairly good agreement is found between experimental and theoretical results for the forced mode shapes and for the resonance frequencies. However, it appears that the two springs used to maintain the disk in position introduce extra clamping conditions. Several source shapes were studied, among which a collection of an arbitrary number of forces is particularly useful. The two-dimensional wavenumber representation shows the presence of anisotropy related to the crystallographic axes at higher frequencies, which is not predicted by the model. The experimental phase velocities are compared to those given by the classical theory of disks and to those of Lamb A(0) mode. This study confirms the correspondence at low frequencies between the A(0) mode and the bending eigenmodes of a disk with finite size.

  14. Outbreak of silicosis in Spanish quartz conglomerate workers.

    Science.gov (United States)

    Pérez-Alonso, Aránzazu; Córdoba-Doña, Juan Antonio; Millares-Lorenzo, José Luis; Figueroa-Murillo, Estrella; García-Vadillo, Cristina; Romero-Morillos, José

    2014-01-01

    To describe the epidemiological and clinical characteristics of an outbreak of occupational silicosis and the associated working conditions. Cases were defined as men working in the stone cutting, shaping, and finishing industry in the province of Cádiz, diagnosed with silicosis between July 2009 and May 2012, and were identified and diagnosed by the department of pulmonology of the University Hospital of Puerto Real (Cádiz). A census of workplaces using quartz conglomerates was carried out to determine total numbers of potentially exposed workers. A patient telephone survey on occupational exposures and a review of medical records for all participants were conducted. Silicosis was diagnosed in 46 men with a median age of 33 years and a median of 11 years working in the manufacturing of countertops. Of these cases, 91.3% were diagnosed with simple chronic silicosis, with an abnormal high-resolution computerized tomography (HRCT) scan. One patient died during the study period. Employer non-compliance in prevention and control measures was frequently reported, as were environmental and individual protection failures. The use of new construction materials such as quartz conglomerates has increased silicosis incidence due to intensive occupational exposures, in the context of high demand fuelled by the housing boom. This widespread exposure poses a risk if appropriate preventive measures are not undertaken.

  15. Electronic Nose using Gas Chromatography Column and Quartz Crystal Microbalance

    Directory of Open Access Journals (Sweden)

    Hari Agus Sujono

    2011-08-01

    Full Text Available The conventional electronic nose usually consists of an array of dissimilar chemical sensors such as quartz crystal microbalance (QCM combined with pattern recognition algorithm such as Neural network. Because of parallel processing, the system needs a huge number of sensors and circuits which may emerge complexity and inter-channel crosstalk problems. In this research, a new type of odor identification which combines between gas chromatography (GC and electronic nose methods has been developed. The system consists of a GC column and a 10-MHz quartz crystal microbalance sensor producing a unique pattern for an odor in time domain. This method offers advantages of substantially reduced size, interferences and power consumption in comparison to existing odor identification system. Several odors of organic compounds were introduced to evaluate the selectivity of the system. Principle component analysis method was used to visualize the classification of each odor in two-dimensional space. This system could resolve common organic solvents, including molecules of different classes (aromatic from alcohols as well as those within a particular class (methanol from ethanol and also fuels (premium from pertamax. The neural network can be taught to recognize the odors tested in the experiment with identification rate of 85 %. It is therefore the system may take the place of human nose, especially for poisonous odor evaluations.

  16. Analytical model for CO(2) laser ablation of fused quartz.

    Science.gov (United States)

    Nowak, Krzysztof M; Baker, Howard J; Hall, Denis R

    2015-10-10

    This paper reports the development of an analytical model, with supporting experimental data, which quite accurately describes the key features of CO2 laser ablation of fused silica glass. The quantitative model of nonexplosive, evaporative material removal is shown to match the experimental data very well, to the extent that it can be used as a tool for ablative measurements of absorption coefficient and vaporization energy. The experimental results indicated that a minimum of 12  MJ kg-1 is required to fully vaporize fused quartz initially held at room temperature, which is in good agreement with the prediction of the model supplied with input data available in the literature. An optimal window for the machining of fused quartz was revealed in terms of pulse duration 20-80 μs and CO2 laser wavelength optimized for maximum absorption coefficient. Material removal rates of 0.33 μm per J cm-2 allow for a high-precision depth control with modest laser stability. The model may also be used as a parameter selection guide for CO2 laser ablation of fused silica or other materials of similar thermophysical properties.

  17. Mass production of CNTs using CVD multi-quartz tubes

    Energy Technology Data Exchange (ETDEWEB)

    Yousef, Samy; Mohamed, Alaa [Dept. of Production Engineering and Printing Technology, Akhbar Elyom Academy, Giza (Egypt)

    2016-11-15

    Carbon nanotubes (CNTs) have become the backbone of modern industries, including lightweight and heavy-duty industrial applications. Chemical vapor deposition (CVD) is considered as the most common method used to synthesize high yield CNTs. This work aims to develop the traditional CVD for the mass production of more economical CNTs, meeting the growing CNT demands among consumers by increasing the number of three particular reactors. All reactors housing is connected by small channels to provide the heat exchange possibility between the chambers, thereby decreasing synthesis time and reducing heat losses inside the ceramic body of the furnace. The novel design is simple and cheap with a lower reacting time and heat loss compared with the traditional CVD design. Methane, hydrogen, argon, and catalyzed iron nanoparticles were used as a carbon source and catalyst during the synthesis process. In addition, CNTs were produced using only a single quartz tube for comparison. The produced samples were examined using XRD, TEM, SEM, FTIR, and TGA. The results showed that the yield of CNTs increases by 287 % compared with those synthesized with a single quartz tube. Moreover, the total synthesis time of CNTs decreases by 37 % because of decreased heat leakage.

  18. Threshold sensitivity of quartz variometers with negative feedback

    Science.gov (United States)

    Odintsov, V. I.; Petrov, V. G.

    2017-05-01

    The maximum achievable parameters of magnetometers based on optomechanical quartz variometers are studied in connection with the planned transition of the international network Intermagnet to 1-s recording and the need to provide the network of Russian geomagnetic observatories with domestic magnetometers that satisfy Intermagnet requirements. The mechanism of negative feedback effect on the sensitivity threshold of a variometer with an optoelectronic angle transducer is shown. The optimization criterion for the size and shape of the magnets made of different magnetic materials is defined by the maximum ratio of the magnetic moment to the inertial moment. Theoretical and experimental evaluation of the variometer noise level is based on vicalloy and samarium-cobalt. It is shown that the frequency range of magnetometers with variometers based on vicalloy and samarium-cobalt will be bounded from above by frequencies of 1.6 and 6.4 Hz, respectively, at a threshold sensitivity of about 1 pT. These ratios of the frequency and threshold sensitivity for the given magnetic materials are probably limited for quartz variometers with an optoelectronic angle transducer.

  19. Outbreak of silicosis in Spanish quartz conglomerate workers

    Science.gov (United States)

    Pérez-Alonso, Aránzazu; Córdoba-Doña, Juan Antonio; Millares-Lorenzo, José Luis; Figueroa-Murillo, Estrella; García-Vadillo, Cristina; Romero-Morillo, José

    2014-01-01

    Objectives: To describe the epidemiological and clinical characteristics of an outbreak of occupational silicosis and the associated working conditions. Methods: Cases were defined as men working in the stone cutting, shaping, and finishing industry in the province of Cádiz, diagnosed with silicosis between July 2009 and May 2012, and were identified and diagnosed by the department of pulmonology of the University Hospital of Puerto Real (Cádiz). A census of workplaces using quartz conglomerates was carried out to determine total numbers of potentially exposed workers. A patient telephone survey on occupational exposures and a review of medical records for all participants were conducted. Results: Silicosis was diagnosed in 46 men with a median age of 33 years and a median of 11 years working in the manufacturing of countertops. Of these cases, 91.3% were diagnosed with simple chronic silicosis, with an abnormal high-resolution computerized tomography (HRCT) scan. One patient died during the study period. Employer non-compliance in prevention and control measures was frequently reported, as were environmental and individual protection failures. Conclusions: The use of new construction materials such as quartz conglomerates has increased silicosis incidence due to intensive occupational exposures, in the context of high demand fuelled by the housing boom. This widespread exposure poses a risk if appropriate preventive measures are not undertaken. PMID:24804337

  20. Controls on polyacrylamide adsorption to quartz, kaolinite, and feldspar

    Science.gov (United States)

    Graveling, Gary J.; Vala Ragnarsdottir, K.; Allen, Geoff C.; Eastman, John; Brady, Patrick V.; Balsley, Steven D.; Skuse, David R.

    1997-09-01

    Potentiometric titrations of quartz, kaolinite, feldspar, and partially hydrolysed polyacrylamide (HPAM), and sorption measurements of HPAM on the minerals, allows identification of the general mechanisms of polyacrylamide adsorption to aluminosilicates and quartz. Adsorption was monitored at the mineral solution interface by way of X-ray photoelectron spectroscopy (XPS). XPS spectra of the unreacted minerals show bands in the Ols, Si2p, Al2p, and Cls regions. Additional peaks are observed in the C1s and N1s regions after treatment with polyacrylamide and the latter is used in this study to monitor polymer adsorption. N1s peak intensities increase with polymer concentration to a maximum corresponding to surface site saturation. At a fixed polymer concentration, adsorption varies with pH-dependent surface charge. The adsorption mechanism changes with pH, reflecting variation in the pH-dependent concentrations of ionizable groups on polyacrylamide and at aluminosilicate surfaces, and the extent of hydrogen-bonding between uncharged mineral surface sites and polymer amide groups.

  1. Assessing rare earth elements in quartz rich geological samples.

    Science.gov (United States)

    Santoro, A; Thoss, V; Ribeiro Guevara, S; Urgast, D; Raab, A; Mastrolitti, S; Feldmann, J

    2016-01-01

    Sodium peroxide (Na2O2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being (157)Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g(-1), as well as measurement repeatability below 15%. Overall, the Na2O2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Applications of quartz tuning forks in spectroscopic gas sensing

    Science.gov (United States)

    Kosterev, Anatoliy A.; Tittel, Frank K.; Serebryakov, Dmitry V.; Malinovsky, Alexander L.; Morozov, Igor V.

    2005-04-01

    A recently introduced approach to photoacoustic detection of trace gases utilizing a quartz tuning fork (TF) as a resonant acoustic transducer is described in detail. Advantages of the technique called quartz-enhanced photoacoustic spectroscopy (QEPAS) compared to conventional resonant photoacoustic spectroscopy include QEPAS sensor immunity to environmental acoustic noise, a simple absorption detection module design, and its capability to analyze gas samples ˜1mm3 in volume. Noise sources and the TF properties as a function of the sampled gas pressure, temperature and chemical composition are analyzed. Previously published results for QEPAS based chemical gas sensing are summarized. The achieved sensitivity of 5.4×10-9cm-1W/√Hz is compared to recent published results of photoacoustic gas sensing by other research groups. An experimental study of the long-term stability of a QEPAS-based ammonia sensor is presented. The results of this study indicate that the sensor exhibits very low drift, which allows data averaging over >3h of continuous concentration measurements. Architecture and practical implementation of autonomous QEPAS-sensor controller electronics is described. Future developments of QEPAS technique are outlined.

  3. Theoretical analysis of a quartz-enhanced photoacoustic spectroscopy sensor

    Science.gov (United States)

    Petra, N.; Zweck, J.; Kosterev, A. A.; Minkoff, S. E.; Thomazy, D.

    2009-03-01

    Quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors are based on a recent approach to photoacoustic detection which employs a quartz tuning fork as an acoustic transducer. These sensors enable detection of trace gases for air quality monitoring, industrial process control, and medical diagnostics. To detect a trace gas, modulated laser radiation is directed between the tines of a tuning fork. The optical energy absorbed by the gas results in a periodic thermal expansion which gives rise to a weak acoustic pressure wave. This pressure wave excites a resonant vibration of the tuning fork thereby generating an electrical signal via the piezoelectric effect. This paper describes a theoretical model of a QEPAS sensor. By deriving analytical solutions for the partial differential equations in the model, we obtain a formula for the piezoelectric current in terms of the optical, mechanical, and electrical parameters of the system. We use the model to calculate the optimal position of the laser beam with respect to the tuning fork and the phase of the piezoelectric current. We also show that a QEPAS transducer with a particular 32.8 kHz tuning fork is 2-3 times as sensitive as one with a 4.25 kHz tuning fork. These simulation results closely match experimental data.

  4. Quartz-enhanced photo-acoustic spectroscopy for breath analyses

    Science.gov (United States)

    Petersen, Jan C.; Lamard, Laurent; Feng, Yuyang; Focant, Jeff-F.; Peremans, Andre; Lassen, Mikael

    2017-03-01

    An innovative and novel quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor for highly sensitive and selective breath gas analysis is introduced. The QEPAS sensor consists of two acoustically coupled micro- resonators (mR) with an off-axis 20 kHz quartz tuning fork (QTF). The complete acoustically coupled mR system is optimized based on finite element simulations and experimentally verified. Due to the very low fabrication costs the QEPAS sensor presents a clear breakthrough in the field of photoacoustic spectroscopy by introducing novel disposable gas chambers in order to avoid cleaning after each test. The QEPAS sensor is pumped resonantly by a nanosecond pulsed single-mode mid-infrared optical parametric oscillator (MIR OPO). Spectroscopic measurements of methane and methanol in the 3.1 μm to 3.7 μm wavelength region is conducted. Demonstrating a resolution bandwidth of 1 cm-1. An Allan deviation analysis shows that the detection limit at optimum integration time for the QEPAS sensor is 32 ppbv@190s for methane and that the background noise is solely due to the thermal noise of the QTF. Spectra of both individual molecules as well as mixtures of molecules were measured and analyzed. The molecules are representative of exhaled breath gasses that are bio-markers for medical diagnostics.

  5. The Suitability Of Local Quartz Sand In The Production Of Bath Crucibles.

    OpenAIRE

    C. O. Okpanachi; S. I. Ibrahim; A. C. Okoro; K. Dogo; M. K. Idris

    2015-01-01

    The suitability of local quartz sand in the production of bath crucibles is a study that was carried out in order to impart overall strength on bath crucibles hence reduce breakages during fettling. Therefore this research constitutes a study to enhance the efficiency of production of bath crucibles by addition of quartz sand in slip preparation. The steps taken in the beneficiation of quartz sand for the production of bath crucibles are comminution which entails crushing and milling classifi...

  6. Molecular dynamics investigation into the adsorption of oil-water-surfactant mixture on quartz

    Science.gov (United States)

    Xuefen, Zhang; Guiwu, Lu; Xiaoming, Wen; Hong, Yang

    2009-04-01

    Molecular dynamics (MD) simulations have been carried out to investigate the adsorption behavior of different surfactants-water-oil mixture on quartz surfaces. The effects of rhamnolipid, sodium dodecyl benzene sulfonate and sodium hexadecyl sulfonate on binding energy and radial distribution function (RDF) of oil-quartz are calculated at molecular level. The study shows that these surfactants can reduce binding energy between oil molecules and quartz surface, which plays a role of oil-displacing agent.

  7. Hydrothermal Synthesis of Monodisperse Single-Crystalline Alpha-Quartz Nanospheres

    Science.gov (United States)

    Jiang, Xingmao; Jiang, Ying-Bing

    2014-01-01

    Uniformly-sized, single-crystal alpha-quartz nanospheres have been synthesized at 200°C and 15atm under continuous stirring starting from uniform, amorphous Stöber silica colloids and using NaCl and alkali hydroxide as mineralizers. Quartz nanosphere size is controlled by the colloid particle size via direct devitrification. Uniform, high-purity nanocrystalline quartz is important for understanding nanoparticle toxicology and for advanced polishing and nanocomposite fabrication. PMID:21629887

  8. Quartz preferred orientation in naturally deformed mylonitic rocks (Montalto shear zone-Italy): a comparison of results by different techniques, their advantages and limitations

    Science.gov (United States)

    Fazio, Eugenio; Punturo, Rosalda; Cirrincione, Rosolino; Kern, Hartmut; Pezzino, Antonino; Wenk, Hans-Rudolf; Goswami, Shalini; Mamtani, Manish A.

    2017-10-01

    In the geologic record, the quartz c-axis patterns are widely adopted in the investigation of crystallographic preferred orientations (CPO) of naturally deformed rocks. To this aim, in the present work, four different methods for measuring quartz c-axis orientations in naturally sheared rocks were applied and compared: the classical universal stage technique, the computer-integrated polarization microscopy method (CIP), the time-of-flight (TOF) neutron diffraction analysis , and the electron backscatter diffraction (EBSD). Microstructural analysis and CPO patterns of quartz, together with the ones obtained for feldspars and micas in mylonitic granitoid rocks, have been then considered to solve structural and geological questions related to the Montalto crustal scale shear zone (Calabria, southern Italy). Results obtained by applying the different techniques are discussed, and the advantages as well as limitations of each method are highlighted. Importantly, our findings suggest that patterns obtained by means of different techniques are quite similar. In particular, for such mylonites, a subsimple shear (40% simple shear vs 60% pure shear) by shape analysis of porphyroclasts was inferred. A general tendency of an asymmetric c-maximum near to the Z direction (normal to foliation) suggesting dominant basal slip, consistent with fabric patterns related to dynamically recrystallization under greenschist facies, is recognized. Rhombohedral slip was likely active as documented by pole figures of positive and negative rhombs (TOF), which reveal also potential mechanical Dauphiné twinning. Results showed that the most complete CPO characterization on deformed rocks is given by the TOF (from which also other quartz crystallographic axes can be obtained as well as various mineral phases may be investigated). However, this use is restricted by the fact that (a) there are very few TOF facilities around the world and (b) there is loss of any domainal reference, since TOF is a

  9. Methods of assessing grain-size distribution during grain growth

    DEFF Research Database (Denmark)

    Tweed, Cherry J.; Hansen, Niels; Ralph, Brian

    1985-01-01

    This paper considers methods of obtaining grain-size distributions and ways of describing them. In order to collect statistically useful amounts of data, an automatic image analyzer is used, and the resulting data are subjected to a series of tests that evaluate the differences between two related...... distributions (before and after grain growth). The distributions are measured from two-dimensional sections, and both the data and the corresponding true three-dimensional grain-size distributions (obtained by stereological analysis) are collected. The techniques described here are illustrated by reference...

  10. Dynamic and impact contact mechanics of geologic materials: Grain-scale experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Cole, David M.; Hopkins, Mark A.; Ketcham, Stephen A. [Engineer Research and Development Center - Cold Regions Research and Engineering Laboratory, 72 Lyme Rd., Hanover, NH 03755 (United States)

    2013-06-18

    High fidelity treatments of the generation and propagation of seismic waves in naturally occurring granular materials is becoming more practical given recent advancements in our ability to model complex particle shapes and their mechanical interaction. Of particular interest are the grain-scale processes that are activated by impact events and the characteristics of force transmission through grain contacts. To address this issue, we have developed a physics based approach that involves laboratory experiments to quantify the dynamic contact and impact behavior of granular materials and incorporation of the observed behavior indiscrete element models. The dynamic experiments do not involve particle damage and emphasis is placed on measured values of contact stiffness and frictional loss. The normal stiffness observed in dynamic contact experiments at low frequencies (e.g., 10 Hz) are shown to be in good agreement with quasistatic experiments on quartz sand. The results of impact experiments - which involve moderate to extensive levels of particle damage - are presented for several types of naturally occurring granular materials (several quartz sands, magnesite and calcium carbonate ooids). Implementation of the experimental findings in discrete element models is discussed and the results of impact simulations involving up to 5 Multiplication-Sign 105 grains are presented.

  11. Correlation Between Grain Size Distribution and Silicon and Oxygen Contents at Wadi Arar Sediments, Kingdom of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    M. A. M. Alghamdi

    2017-08-01

    Full Text Available Quartz is the major mineral of Wadi Arar sediments. The top two elements contents are oxygen with 63.96 wt%, followed by silicon with 16.35 wt%. There is a positive, weak to medium correlation between grain size and silicon and oxygen contents. The correlation between oxygen and grain size is four times higher than that of silicon. At grain size ranges between 0.8 and 1.0 mm, both oxygen and silicon show the maximum correlation, which decrease gradually with finer and coarser grain sizes. For each element, the correlation between the element content and grain size is a fourth degree polynomial in the grain size. Theoretically, the best two math models that represent the relation between the grain size distribution and each of individual oxygen and silicon content are y=8.84∙ln(x+39.5 and y=2.26∙ln(x+10.1 respectively, where y represents the element content percentage and x represents the corresponding grain size in mm.

  12. MATHEMATICAL MODEL OF GRAIN MICRONIZATION

    Directory of Open Access Journals (Sweden)

    V. A. Afanas’ev

    2014-01-01

    Full Text Available Summary. During micronisation grain moisture evaporates mainly in decreasing drying rate period. Grain layer located on the surface of the conveyor micronisers will be regarded as horizontal plate. Due to the fact that the micronisation process the surface of the grain evaporates little moisture (within 2-7 % is assumed constant plate thickness. Because in the process of micronization grain structure is changing, in order to achieve an exact solution of the equations necessary to take into account changes thermophysical, optical and others. Equation of heat transfer is necessary to add a term that is responsible for the infrared heating. Because of the small thickness of the grain, neglecting the processes occurring at the edge of the grain, that is actually consider the problem of an infinite plate. To check the adequacy of the mathematical model of the process of micronisation of wheat grain moisture content must be comparable to the function of time, obtained by solving the system of equations with the measured experimental data of experience. Numerical solution of a system of equations for the period of decreasing drying rate is feasible with the help of the Maple 14, substituting the values of the constants in the system. Calculation of the average relative error does not exceed 7- 10 %, and shows a good agreement between the calculated data and the experimental values.

  13. Grain mantles: The impact on grain evolution and selective extinction

    Science.gov (United States)

    Joseph, Charles L.

    1989-01-01

    Depletion studies are used to infer the presence of mantles and to constrain grain evolutionary models in the diffuse interstellar medium. The presence of these mantles appears to be important in the evolution of the grains inside diffuse as well as dense clouds. In dense clouds where the element-to-element abundances sometimes differ from those found in diffuse clouds, empirical relationships are starting to emerge between gas abundances and various types of peculiar selective extinction. These peculiar extinction curves may be the results of nonvolatile mantle formation on grain cores or may reflect chemical differences due to variations in the intrinsic metalicity from one cloud to another. A simple model of the time evolution of a parcel of gas and dust as observed by the depletion of two elements is presented. Different studies of grain evolution and selective extinction are discussed and compared.

  14. Quartz-Enhanced Photoacoustic Detection for Aerosol Optical Characterization

    Science.gov (United States)

    Hollinger, M.; Black, N.; Mazzoleni, C.

    2010-12-01

    Particulate matter emitted by anthropogenic and natural sources strongly affect the radiative budget of the Earth. Non-absorbing aerosols have a negative radiative forcing effect, acting to cool the planet and thereby masking the warming caused by greenhouse gases. Absorbing aerosols including black carbon, dust and brown carbon can provide positive radiative forcing at the top of the atmosphere depending on their optical properties. Due to its short atmospheric lifetime, black carbon can have a strong regional effect (e.g. in Himalaya and in the Arctic, where surface albedo is high). How much aerosols affect the Earth’s climate however remains highly uncertain. Providing accurate, widespread and unbiased measurements of aerosol optical properties is important for understanding how aerosols will affect the future climate system. However, in depth studies on aerosol optical properties, and in particular absorption, are still lacking. Photoacoustic spectrometry has been recently employed to measure aerosol absorption. The technique is more fundamental and unbiased then traditional filter-based techniques. This type of spectrometry exploits the photoacoustic effect, which is the production of an acoustic wave from the excitation of a particle absorbing a photon. Currently available commercial spectrometers are very useful for laboratory and field experiments, but due to their typical size, they are unpractical for studies employing small payload aircrafts (e.g. unmanned aircrafts) or balloons. A recent development in photoacoustic spectrometry reported by Kosterev et al. in 2002 is the use of a quartz tuning fork for the detection, termed Quartz-Enhanced Photoacoustic Spectrometry (QEPAS). Due to the high resonance frequency (~32 KHz) of the tuning fork, QEPAS has good potential for the miniaturization of a photoacoustic spectrometry system. The quartz tuning fork is piezoelectric, and a signal is generated only when the tines of the tuning fork move in opposite

  15. Properties of ultrasmall superconducting grains

    CERN Document Server

    Lorenzo, A D; Fazio, R; Giaquinta, G; Mastellone, A; Hekking, F W J

    1999-01-01

    We briefly review some properties of ultrasmall superconducting grains. The ground state and the first excited states of the grains are analyzed by studying the parity gap and the spectroscopic gap. Both quantities turn out to be parity dependent and universal functions of the ratio between the level spacing and the BCS gap, delta/DELTA. pairing correlations show up also in the thermodynamic quantities. The presence of a BCS interaction is responsible for an anomaly in the spin susceptibility as a function of temperature. This anomaly persists also in very small grains.

  16. Red grain mycetoma foot in Western Rajasthan

    OpenAIRE

    Mathur D; Prakash Prabhu; Gupta P; Purohit Asha; Vyas MCR

    1994-01-01

    Usually the colour of the grains seen in cases of mycetoma are either black or yellow. Recently there were reports that unusual red grains had been noticed in cases of mycetoma. A case of red grain mycetoma is reported.

  17. Gamma Induced Transparency Loss of Thick Quartz Fibres

    CERN Document Server

    Avezov, Anvar; Gasanov, Eldar; Ibragimova, Elvira; Rustamov, Igor; Ulughbek, P; Volodko, Anton; Yuldashev, Bekhzad S

    1997-01-01

    Radiation response of thick multi-mode Ge, P, F -doped quartz fibre has been examined after exposure to 60^Co gamma-source within a dose interval of 10 - 10^7 Gy at a dose power of 2.3 and 24 Gy/s at 300K. The induced transparency losses A at the wave length of 1.06 mkm do not exceed 0.2 after a dose of 10^6 Gy and reach a saturation, while the fibres are closed for visible light after a smaller dose. Varying focus and an angle of leading a probe light beam in fibre, the core modes were found to close at a dose of 10^4 Gy due to radiation induced colour centres of Ge and non-bridging oxygen O, and the clad modes were suppressed at 500 Gy by the expense of Al impurity colour centres.

  18. Measuring the diffraction properties of an imaging quartz(211) crystal

    Energy Technology Data Exchange (ETDEWEB)

    Haugh, M. J.; Jacoby, K. D.; Koch, J. A. [National Security Technologies, LLC, Livermore, California 94550 (United States); Chen, H.; Schneider, M. B. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Hill, K. W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2016-06-15

    A dual goniometer X-ray system was used to measure the reflectivity curve for a spherically bent quartz(211) crystal. An analysis of the dual goniometer instrument response function for the rocking curve width measurement was developed and tested against the actual measurements. The rocking curve was measured at 4510.8 eV using the Ti Kα1 characteristic spectral line. The crystal is the dispersion element for a high resolution spectrometer used for plasma studies. It was expected to have a very narrow rocking curve width. The analysis showed that we could measure the upper bound for the rocking curve width of the Qz(211) crystal. The upper bound was 58 μrad giving a lower bound for the instrument resolving power E/ΔE = 34 000. Greatly improved insight into the dual goniometer operation and its limitations was achieved.

  19. Respiratory Monitoring by Porphyrin Modified Quartz Crystal Microbalance Sensors

    Directory of Open Access Journals (Sweden)

    Seung-Woo Lee

    2011-01-01

    Full Text Available A respiratory monitoring system based on a quartz crystal microbalance (QCM sensor with a functional film was designed and investigated. Porphyrins 5,10,15,20-tetrakis-(4-sulfophenyl-21H,23H-porphine (TSPP and 5,10,15,20-tetrakis-(4-sulfophenyl-21H, 23H-porphine manganese (III chloride (MnTSPP used as sensitive elements were assembled with a poly(diallyldimethyl ammonium chloride (PDDA. Films were deposited on the QCM resonators using layer-by-layer method in order to develop the sensor. The developed system, in which the sensor response reflects lung movements, was able to track human respiration providing respiratory rate (RR and respiratory pattern (RP. The sensor system was tested on healthy volunteers to compare RPs and calculate RRs. The operation principle of the proposed system is based on the fast adsorption/desorption behavior of water originated from human breath into the sensor films deposited on the QCM electrode.

  20. Finite Element Analysis of Electrically Excited Quartz Tuning Fork Devices

    Science.gov (United States)

    Oria, Roger; Otero, Jorge; González, Laura; Botaya, Luis; Carmona, Manuel; Puig-Vidal, Manel

    2013-01-01

    Quartz Tuning Fork (QTF)-based Scanning Probe Microscopy (SPM) is an important field of research. A suitable model for the QTF is important to obtain quantitative measurements with these devices. Analytical models have the limitation of being based on the double cantilever configuration. In this paper, we present an electromechanical finite element model of the QTF electrically excited with two free prongs. The model goes beyond the state-of-the-art of numerical simulations currently found in the literature for this QTF configuration. We present the first numerical analysis of both the electrical and mechanical behavior of QTF devices. Experimental measurements obtained with 10 units of the same model of QTF validate the finite element model with a good agreement. PMID:23722828

  1. Finite Element Analysis of Electrically Excited Quartz Tuning Fork Devices

    Directory of Open Access Journals (Sweden)

    Manel Puig-Vidal

    2013-05-01

    Full Text Available Quartz Tuning Fork (QTF-based Scanning Probe Microscopy (SPM is an important field of research. A suitable model for the QTF is important to obtain quantitative measurements with these devices. Analytical models have the limitation of being based on the double cantilever configuration. In this paper, we present an electromechanical finite element model of the QTF electrically excited with two free prongs. The model goes beyond the state-of-the-art of numerical simulations currently found in the literature for this QTF configuration. We present the first numerical analysis of both the electrical and mechanical behavior of QTF devices. Experimental measurements obtained with 10 units of the same model of QTF validate the finite element model with a good agreement.

  2. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism.

    Science.gov (United States)

    Liu, Yongning; Chang, Jun; Lian, Jie; Liu, Zhaojun; Wang, Qiang; Qin, Zengguang

    2016-02-06

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 compared with the original signal, which was acquired without resonators or a prism. In addition, the system noise was reduced a little with double resonators due to the Q factor decrease. The signal-to-noise ratio (SNR) was greatly improved. Additionally, a normalized noise equivalent absorption coefficient (NNEA) of 5.8 × 10(-8) W·cm(-1)·Hz(-1/2) was achieved for water vapor detection in the atmosphere.

  3. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    Directory of Open Access Journals (Sweden)

    Yongning Liu

    2016-02-01

    Full Text Available A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 compared with the original signal, which was acquired without resonators or a prism. In addition, the system noise was reduced a little with double resonators due to the Q factor decrease. The signal-to-noise ratio (SNR was greatly improved. Additionally, a normalized noise equivalent absorption coefficient (NNEA of 5.8 × 10−8 W·cm−1·Hz−1/2 was achieved for water vapor detection in the atmosphere.

  4. Optical Detection Technique Using Quartz-Enhanced Photoacoustic Spectrum

    Science.gov (United States)

    Wu, Hongpeng; Zhang, Dongdong; Dong, Lei; Zheng, Huadan; Liu, Yanyan; Yin, Wangbao; Ma, Weiguang; Zhang, Lei; Jia, Suotang

    2015-06-01

    A new optical detection approach based on quartz-enhanced photoacoustic spectroscopy (QEPAS) to detect gases is developed. The new method not only employs a modulated laser to excite acoustic wave, as the general QEPAS does, but also adds an extra laser beam without modulation as the detection source to transform the prong vibration into a laser intensity change. Due to the mechanical vibration of the prongs, the intensity of the reflection laser beam is modulated. Thus, the information of the target gas (composition, concentration, etc.) is obtained by demodulating the reflected light. The achieved sensitivity of is inter-compared to the sensitivity of the conventional QEPAS. Further developments of the new optical detection approach are also discussed in detail.

  5. Is quartz a potential indicator of ultrahigh-pressure metamorphism? Laser Raman spectroscopy of quartz inclusions in ultrahigh-pressure garnets

    OpenAIRE

    Korsakov, Andrey V.; Perraki, Maria; Zhukov, Vladimir P.; De Gussem, Kris; Vandenabeele, Peter; Tomilenko, Anatoly A.

    2009-01-01

    Laser Raman microspectroscopy was applied to quartz inclusions in coesite- and diamond-grade metapelites from the Kokchetav ultrahigh-pressure metamorphic (UHPM) complex, Northern Kazakhstan, and diamond-grade eclogite xenoliths from the Mir kimberlite pipe, Yakutiya, Russia to assess the quantitative correlation between the Raman frequency shift and metamorphic pressure. Quartz crystals sealed in garnets have a higher frequency shift than those in the matrix. Residual pressures retained by q...

  6. Thermoluminescence response of natural white quartz collected from Gelephu, Bhutan

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, J.M., E-mail: jitukalita09@gmail.com; Wary, G.

    2016-09-15

    Highlights: • TL response of natural white quartz collected from Gelephu, Bhutan was studied. • There was five trapping sites at depths ∼0.68, 0.90, 0.97, 1.06 and 1.10 eV. • The 426 K TL peak showed linear dose response from 10 mGy to 10 Gy. • The 426 K TL peak was found to fade very slowly. - Abstract: TL properties of natural quartz mineral collected from Gelephu, (Bhutan) were studied. With the help of various characterization techniques the quality of the sample was tested. The thermoluminescence (TL) analysis was carried out under X-ray irradiation. The un-irradiated sample showed no TL signal; however, after X-ray irradiation, a composite glow curve was observed. The kinetic analysis of the glow curve was carried out and it was observed that there was five trapping sites at depths ∼0.68, 0.90, 0.97, 1.06 and 1.10 eV responsible for five closely spaced glow peaks at ∼341, 362, 383, 397 and 426 K respectively. The dosimetric features of the mineral were studied. The response when studied from the whole glow curve was non-linear. However, the dose response studied from the 426 K peak was found to be linear from 10 mGy to 10 Gy. The fading of the TL signal of this 426 K peak was ∼12% within 5 days after irradiation and onward it was ∼4% up to 30 days. The reproducibility of the results was also good.

  7. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  8. Dense, finely, grained composite materials

    Science.gov (United States)

    Dunmead, Stephen D.; Holt, Joseph B.; Kingman, Donald D.; Munir, Zuhair A.

    1990-01-01

    Dense, finely grained composite materials comprising one or more ceramic phase or phase and one or more metallic and/or intermetallic phase or phases are produced by combustion synthesis. Spherical ceramic grains are homogeneously dispersed within the matrix. Methods are provided, which include the step of applying mechanical pressure during or immediately after ignition, by which the microstructures in the resulting composites can be controllably selected.

  9. Effect of substitution of sand stone dust for quartz and clay in triaxial ...

    Indian Academy of Sciences (India)

    Effect of substitution of sand stone dust for quartz and clay in triaxial porcelain composition. M K HALDAR and S K DAS. ∗. Refractories Division, CSIR-Central Glass & Ceramic Research Institute, 196, Raja S.C. Mullick Road,. Kolkata 700 032, India. MS received 6 July 2011; revised 8 February 2012. Abstract. Quartz and ...

  10. The Cherenkov correlated timing detector beam test results from quartz and acrylic bars

    CERN Document Server

    Sugaya, Y; Yoshimura, Y; Kanda, S; Olsen, S; Ueno, K; Varner, G S; Bergfeld, T; Bialek, J J; Lorenc, J; Palmer, M; Rudnick, G; Selen, M; Auran, T; Boyer, V; Honscheid, K; Tamura, N; Yoshimura, K; Lü, C; Marlow, D R; Mindas, C R; Prebys, E J; Asai, M; Kimura, A; Hayashi, S

    1995-01-01

    Several prototypes of a Cherenkov Correlated Timing (CCT) Detector have been tested at the KEK-PS test beam line. We describe the results for Cherenkov light yields and timing characteristics from quartz and acrylic bar prototypes. A Cherenkov angle resolution is found to be 15 mrad at a propagation distance of 100 cm with a 2 cm thick quartz bar prototype.

  11. The Suitability Of Local Quartz Sand In The Production Of Bath Crucibles.

    Directory of Open Access Journals (Sweden)

    C. O. Okpanachi

    2017-03-01

    Full Text Available The suitability of local quartz sand in the production of bath crucibles is a study that was carried out in order to impart overall strength on bath crucibles hence reduce breakages during fettling. Therefore this research constitutes a study to enhance the efficiency of production of bath crucibles by addition of quartz sand in slip preparation. The steps taken in the beneficiation of quartz sand for the production of bath crucibles are comminution which entails crushing and milling classification washing liquid dispersion sizing and reduction of iron content by magnetic separation. The slip contains materials like plastic clay feldspar kaolin talc sodium silicate water quartz sand etc. These were all milled in the ball mill for slip production casting and fettling glazing and sintering to get final bath crucibles as the end products. Quartz sand is used in a variety of products essentially as raw material for the foundry casting and glass industries and also in chemicals water filtration and ceramics the heat resistance nature of quartz sand makes it an excellent refractory substance for these industrial processes. Slip can be prepared for production of bath crucibles without the inclusion of quartz sand however the addition of quartz sand is needed to improve the mechanical performance of the slip in the production of bath crucibles.

  12. Effect of substitution of sand stone dust for quartz and clay in triaxial ...

    Indian Academy of Sciences (India)

    Quartz and kaolin were partially substituted by sand stone dust (a siliceous byproduct of Indian stone cutting and polishing industries) in a traditional triaxial porcelain composition consisting of kaolin, quartz and feldsper. The effect of substitution upon heating at different temperatures (1050–1150°C) were studied by ...

  13. Detection of Sarin with a Fluorinated Polymer-coated Quartz Crystal ...

    African Journals Online (AJOL)

    A quartz crystal microbalance (QCM) modified with a thin layer of fluorinated polymer was utilized to determine sarin. Determination was based on the frequency shifts due to the adsorption and desorption of the compound at the surface of a modified quartz crystal electrode. Fluorosiloxane was synthesized and deposited ...

  14. Detection of Sarin with a Fluorinated Polymer-coated Quartz Crystal ...

    African Journals Online (AJOL)

    NJD

    2007-09-07

    Sep 7, 2007 ... A quartz crystal microbalance (QCM) modified with a thin layer of fluorinated polymer was utilized to determine sarin. Determination was based on the frequency shifts due to the adsorption and desorption of the compound at the surface of a modified quartz crystal electrode. Fluorosiloxane was synthesized ...

  15. Cathodoluminescence investigations on quartz cement in sandstones of Khabour Formation from Iraqi Kurdistan region, northern Iraq

    DEFF Research Database (Denmark)

    Omer, Muhamed Fakhri; Friis, Henrik

    The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic...... in silica supply which were classified as very early and early, derived from dissolved biogenic silica that precipitated as opal/microquartz, possibly pre-compactional and of non-luminescent quartz overgrowth type. This was followed by phases whose silica supply derived from pressure solution of quartz......, dissolution of feldspar, and hydrothermal fluids related to major thrust fault event. These successive quartz cement phases showed an increase in luminescence and the development of complicated zonation pattern in late-stage quartz cementation....

  16. Cereal grains, legumes and diabetes.

    Science.gov (United States)

    Venn, B J; Mann, J I

    2004-11-01

    This review examines the evidence for the role of whole grain foods and legumes in the aetiology and management of diabetes. MedLine and SilverPlatter ('Nutrition' and 'Food Science FSTA') databases were searched to identify epidemiological and experimental studies relating to the effects of whole grain foods and legumes on indicators of carbohydrate metabolism. Epidemiological studies strongly support the suggestion that high intakes of whole grain foods protect against the development of type II diabetes mellitus (T2DM). People who consume approximately 3 servings per day of whole grain foods are less likely to develop T2DM than low consumers (grains of potential benefit to glycaemic control including slow release carbohydrate and a high fibre content. A substantial increase in dietary intake of legumes as replacement food for more rapidly digested carbohydrate might therefore be expected to improve glycaemic control and thus reduce incident diabetes. This is consistent with the results of dietary intervention studies that have found improvements in glycaemic control after increasing the dietary intake of whole grain foods, legumes, vegetables and fruit. The benefit has been attributed to an increase in soluble fibre intake. However, prospective studies have found that soluble fibre intake is not associated with a lower incidence of T2DM. On the contrary, it is cereal fibre that is largely insoluble that is associated with a reduced risk of developing T2DM. Despite this, the addition of wheat bran to the diets of diabetic people has not improved indicators of glycaemic control. These apparently contradictory findings might be explained by metabolic studies that have indicated improvement in glucose handling is associated with the intact structure of food. For both grains and legumes, fine grinding disrupts cell structures and renders starch more readily accessible for digestion. The extent to which the intact structure of grains and legumes or the composition of

  17. The grain size(s) of Black Hills Quartzite deformed in the dislocation creep regime

    Science.gov (United States)

    Heilbronner, Renée; Kilian, Rüdiger

    2017-10-01

    General shear experiments on Black Hills Quartzite (BHQ) deformed in the dislocation creep regimes 1 to 3 have been previously analyzed using the CIP method (Heilbronner and Tullis, 2002, 2006). They are reexamined using the higher spatial and orientational resolution of EBSD. Criteria for coherent segmentations based on c-axis orientation and on full crystallographic orientations are determined. Texture domains of preferred c-axis orientation (Y and B domains) are extracted and analyzed separately. Subdomains are recognized, and their shape and size are related to the kinematic framework and the original grains in the BHQ. Grain size analysis is carried out for all samples, high- and low-strain samples, and separately for a number of texture domains. When comparing the results to the recrystallized quartz piezometer of Stipp and Tullis (2003), it is found that grain sizes are consistently larger for a given flow stress. It is therefore suggested that the recrystallized grain size also depends on texture, grain-scale deformation intensity, and the kinematic framework (of axial vs. general shear experiments).

  18. Experimental features of natural thermally assisted OSL (NTA-OSL) signal in various quartz samples; preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Polymeris, George S., E-mail: gspolymeris@ankara.edu.tr [Institute of Nuclear Sciences, Ankara University, Beşevler, 06100 Ankara (Turkey); Şahiner, Eren, E-mail: sahiner@ankara.edu.tr [Institute of Nuclear Sciences, Ankara University, Beşevler, 06100 Ankara (Turkey); Meriç, Niyazi, E-mail: meric@ankara.edu.tr [Institute of Nuclear Sciences, Ankara University, Beşevler, 06100 Ankara (Turkey); Kitis, George, E-mail: gkitis@physics.auth.gr [Laboratory of Nuclear Physics and Elementary Particles, Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2015-04-15

    Highlights: •Intense NTA-OSL signal is ubiquitously monitored for five different quartz samples. •For the NTA-OSL signals of all quartz samples, the optimum measuring temperature was indicated to be at 180 °C. •The NTA-OSL signal comprises of at least two different contributing components. •Developing a SAR TA-OSL protocol is feasible. -- Abstract: The access to the OSL signals from very deep traps is achieved by an alternative experimental method which comprises combined action of thermal and optical stimulation, termed as thermally assisted OSL (TA-OSL). This experimental technique was suggested in order to not only measure the signal of the deep traps without heating the sample to temperatures greater than 500 °C, but also use the former for dosimetry purposes as well, due to exhibiting a number of interesting properties which could be effectively used towards dosimetry purposes, especially for large accumulated artificial doses. The present study provides for the first time in the literature with preliminary results towards the feasibility study of the naturally occurring TA-OSL signal in coarse grains of natural quartz towards its effective application to geological dating. The samples subjected to the present study were collected from fault lines in Kütahya-Simav, Western Anatolia Region, Turkey; independent luminescence approaches yielded an equivalent dose larger than 100 Gy. Several experimental luminescence features were studied, such as sensitivity, reproducibility, TA-OSL curve shape as well as the correlation between NTA-OSL and NTL/NOSL. Nevertheless, special emphasis was addressed towards optimizing the measuring conditions of the TA-OSL signal. The high intensity of the OSL signal confirms the existence of a transfer phenomenon from deep electron traps. The increase of the integrated TA-OSL signal as a function of temperature is monitored for temperatures up to 180 °C, indicating the later as the most effective stimulation temperature

  19. The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifera

    Directory of Open Access Journals (Sweden)

    Fox Patricia M

    2004-04-01

    Full Text Available We examined the chemical reactions influencing dissolved concentrations, speciation, and transport of naturally occurring arsenic (As in a shallow, sand and gravel aquifer with distinct geochemical zones resulting from land disposal of dilute sewage effluent. The principal geochemical zones were: (1 the uncontaminated zone above the sewage plume [350 μM dissolved oxygen (DO, pH 5.9]; (2 the suboxic zone (5 μM DO, pH 6.2, elevated concentrations of sewage-derived phosphate and nitrate; and (3 the anoxic zone [dissolved iron(II 100–300 μM, pH 6.5–6.9, elevated concentrations of sewage-derived phosphate]. Sediments are comprised of greater than 90% quartz but the surfaces of quartz and other mineral grains are coated with nanometer-size iron (Fe and aluminum (Al oxides and/or silicates, which control the adsorption properties of the sediments. Uncontaminated groundwater with added phosphate (620 μM was pumped into the uncontaminated zone while samples were collected 0.3 m above the injection point. Concentrations of As(V increased from below detection (0.005 μM to a maximum of 0.07 μM during breakthrough of phosphate at the sampling port; As(III concentrations remained below detection. These results are consistent with the hypothesis that naturally occurring As(V adsorbed to constituents of the coatings on grain surfaces was desorbed by phosphate in the injected groundwater. Also consistent with this hypothesis, vertical profiles of groundwater chemistry measured prior to the tracer test showed that dissolved As(V concentrations increased along with dissolved phosphate from below detection in the uncontaminated zone to approximately 0.07 and 70 μM, respectively, in the suboxic zone. Concentrations of As(III were below detection in both zones. The anoxic zone had approximately 0.07 μM As(V but also had As(III concentrations of 0.07–0.14 μM, suggesting that release of As bound to sediment grains occurred by desorption by phosphate

  20. The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifer

    Science.gov (United States)

    Kent, D.B.; Fox, P.M.

    2004-01-01

    We examined the chemical reactions influencing dissolved concentrations, speciation, and transport of naturally occurring arsenic (As) in a shallow, sand and gravel aquifer with distinct geochemical zones resulting from land disposal of dilute sewage effluent. The principal geochemical zones were: (1) the uncontaminated zone above the sewage plume [350 ??M dissolved oxygen (DO), pH 5.9]; (2) the suboxic zone (5 ??M DO, pH 6.2, elevated concentrations of sewage-derived phosphate and nitrate); and (3) the anoxic zone [dissolved iron(II) 100-300 ??M, pH 6.5-6.9, elevated concentrations of sewage-derived phosphate]. Sediments are comprised of greater than 90% quartz but the surfaces of quartz and other mineral grains are coated with nanometer-size iron (Fe) and aluminum (Al) oxides and/or silicates, which control the adsorption properties of the sediments. Uncontaminated groundwater with added phosphate (620 ??M) was pumped into the uncontaminated zone while samples were collected 0.3 m above the injection point. Concentrations of As(V) increased from below detection (0.005 ??M) to a maximum of 0.07 ??M during breakthrough of phosphate at the sampling port; As(III) concentrations remained below detection. These results are consistent with the hypothesis that naturally occurring As(V) adsorbed to constituents of the coatings on grain surfaces was desorbed by phosphate in the injected groundwater. Also consistent with this hypothesis, vertical profiles of groundwater chemistry measured prior to the tracer test showed that dissolved As(V) concentrations increased along with dissolved phosphate from below detection in the uncontaminated zone to approximately 0.07 and 70 ??M, respectively, in the suboxic zone. Concentrations of As(III) were below detection in both zones. The anoxic zone had approximately 0.07 ??M As(V) but also had As(III) concentrations of 0.07-0.14 ??M, suggesting that release of As bound to sediment grains occurred by desorption by phosphate, reductive

  1. Fluid-deposited graphitic inclusions in quartz: Comparison between KTB (German Continental Deep-Drilling) core samples and artificially reequilibrated natural inclusions

    Science.gov (United States)

    Pasteris, J.D.; Chou, I.-Ming

    1998-01-01

    We used Raman microsampling spectroscopy (RMS) to determine the degree of crystallinity of minute (2-15 ??m) graphite inclusions in quartz in two sets of samples: experimentally reequilibrated fluid inclusions in a natural quartz grain and biotite-bearing paragneisses from the KTB deep drillhole in SE Germany. Our sequential reequilibration experiments at 725??C on initially pure CO2 inclusions in a quartz wafer and the J. Krautheim (1993) experiments at 900-1100??C on organic compounds heated in gold or platinum capsules suggest that, at a given temperature, (1) fluid-deposited graphite will have a lower crystallinity than metamorphosed organic matter and (2) that the crystallinity of fluid-deposited graphite is affected by the composition of the fluid from which it was deposited. We determined that the precipitation of more-crystalline graphite is favored by lower fH2 (higher fO2), and that the crystallinity of graphite is established by the conditions (including gas fugacities) that pertain as the fluid first reaches graphite saturation. Graphite inclusions within quartz grains in the KTB rocks show a wide range in crystallinity index, reflecting three episodes of carbon entrapment under different metamorphic conditions. Isolated graphite inclusions have the spectral properties of totally ordered, completely crystalline graphite. Such crystallinity suggests that the graphite was incorporated from the surrounding metasedimentary rocks, which underwent metamorphism at upper amphibolite-facies conditions. Much of the fluid-deposited graphite in fluid inclusions, however, shows some spectral disorder. The properties of that graphite resemble those of experimental precipitates at temperatures in excess of 700??C and at elevated pressures, suggesting that the inclusions represent precipitates from C-O-H fluids trapped under conditions near those of peak metamorphism at the KTB site. In contrast, graphite that is intimately associated with chlorite and other

  2. Determination of SiO2 Raman spectrum indicating the transformation from coesite to quartz in Gföhl migmatitic gneisses in the Moldanubian Zone, Czech Republic

    National Research Council Canada - National Science Library

    Tomoyuki KOBAYASHI; Takao HIRAJIMA; Yoshikuni HIROI; Martin SVOJTKA

    2008-01-01

    .... The Raman spectrum is composed of the intense vibrations of quartz at 464, 393 and 266 cm-1 of quartz and the weak vibration of coesite at 521 cm-1 is obtained from the quartz proximal to the relict...

  3. Spinodal decomposition in fine grained materials

    Indian Academy of Sciences (India)

    Unknown

    A-rich grain boundary layer followed by a B-rich layer; the grain interior exhibits a spinodally decomposed microstructure, evolving slowly. Further, grain growth is suppressed completely during the decomposition process. Keywords. Spinodal decomposition; grain boundary effects; phase field models. 1. Introduction.

  4. Use of thin films obtained by plasma polymerization for grain protection and germination enhancement

    Directory of Open Access Journals (Sweden)

    Rodrigo A. M. Carvalho

    2005-12-01

    Full Text Available In this work, preliminary results of the use of hydrophobic thin films obtained by plasma deposition to protect grains and seeds are presented: grains coated by the films did not present biological degradation when stored in a saturated water vapor environment, but had their germination accelerated in the presence of water. A model that explains the difference of behavior of the films when exposed to water in vapor form or in liquid form, based on the formation of microchannels within the film that lead to water uptake in seeds, is presented. The model was successfully tested using quartz crystal measurements, which showed that the microchannels within the films can favor the adsorption and permeation of water when the films are immersed in water.

  5. Sticking properties of ice grains

    Science.gov (United States)

    Jongmanns, M.; Kumm, M.; Wurm, G.; Wolf, D. E.; Teiser, J.

    2017-06-01

    We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced) particle radii, which differ significantly from the linear dependence of common contact theories.

  6. Sticking properties of ice grains

    Directory of Open Access Journals (Sweden)

    Jongmanns M.

    2017-01-01

    Full Text Available We study the size dependence of pull-off forces of water ice in laboratory experiments and numerical simulations. To determine the pull-off force in our laboratory experiments, we use a liquid nitrogen cooled centrifuge. Depending on its rotation frequency, spherical ice grains detach due to the centrifugal force which is related to the adhesive properties. Numerical simulations are conducted by means of molecular dynamics simulations of hexagonal ice using a standard coarse-grained water potential. The pull-off force of a single contact between two spherical ice grains is measured due to strain controlled simulations. Both, the experimental study and the simulations reveal a dependence between the pull-off force and the (reduced particle radii, which differ significantly from the linear dependence of common contact theories.

  7. Experimental and modelling study of pulsed optically stimulated luminescence in quartz, marble and beta irradiated salt

    Energy Technology Data Exchange (ETDEWEB)

    Pagonis, V; Mian, S M; Barnold, C [Physics Department, McDaniel College, Westminster, MD 21158 (United States); Chithambo, M L [Department of Physics, Rhodes University, PO Box 94, Grahamstown 6140 (South Africa); Christensen, E, E-mail: vpagonis@mcdaniel.ed [Physics Department, Virginia Tech, VA 24061 (United States)

    2009-03-07

    Optical stimulation luminescence (OSL) signals can be obtained using continuous-wave optical stimulation (CW-OSL), the linear modulation optical stimulation method (LM-OSL) and the time-resolved optical stimulation (TR-OSL) method. During TR-OSL measurements, the stimulation and emission of luminescence are experimentally separated in time by using short light pulses. This paper presents new TR-OSL data for annealed high purity synthetic quartz, for marble and for commercially available iodized salt. A new type of behaviour for TR-OSL signals for quartz and iodized salt is presented, in which the OSL signal exhibits a nonmonotonic behaviour during optical stimulation; this type of behaviour has not been reported previously in the literature for quartz. Furthermore, a luminescence component with very long luminescence lifetime is reported for some quartz aliquots, which may be due to the presence of a delayed-OSL (DOSL) mechanism in quartz. A new kinetic model for TR-OSL in quartz is presented, which is based on a main electron trap and on several luminescence centres. The model is used to quantitatively fit several sets of experimental data of pulsed optically stimulated luminescence from quartz.

  8. Mechano-Chemical Preparation of Powder QUARTZ/TiO2 Composite Particles

    Science.gov (United States)

    Du, Gao-Xiang; He, Hao; Liao, Li-Bing; Wang, Li-Juan

    2013-03-01

    Titanium dioxide pigment is a white pigment of high performance. However, its production could cause severe environmental and resource problems. In this paper, powder quartz/TiO2 composite particles (PQ/TCP), a type of core (powder quartz)-shell(TiO2) composite powder, were prepared by a mechano-chemical method. The pigment properties of PQ/TCP and the mechanism of the mechano-chemical reaction between quartz and TiO2 were investigated. Orthogonal analyses of experimental vairables showed optimal pigment characteristics of PQ/TCP under the following conditions: 4 h of activation for powder quartz, mixing/grinding at 1000 rpm for 1 h, with a mixing slurry made of 50% powder quartz and 0.4% dispersant. Powder quartz was evenly coated by TiO2 and the Si-O-Ti bond was formed between powder quartz and TiO2 in PQ/TCP as revealed by FTIR analyses and confirmed by surface thermodynamic calculation.

  9. Quartz in ash, and air in a high lung cancer incidence area in China.

    Science.gov (United States)

    Downward, George S; Hu, Wei; Rothman, Nat; Reiss, Boris; Tromp, Peter; Wu, Guoping; Wei, Fusheng; Xu, Jun; Seow, Wei Jie; Chapman, Robert S; Lan, Qing; Vermeulen, Roel

    2017-02-01

    Exposure to crystalline silica (quartz) has been implicated as a potential cause of the high lung cancer rates in the neighbouring counties of Xuanwei and Fuyuan, China, where the domestic combustion of locally sourced "smoky" coal (a bituminous coal) is responsible for some of the highest lung cancer rates in the nation, irrespective of gender or smoking status. Previous studies have shown that smoky coal contains approximately twice as much quartz when compared to alternative fuels in the area, although it is unclear how the quartz in coal relates to household air pollution. Samples of ash and fine particulate matter (PM 2.5 ) were collected from 163 households and analysed for quartz content by Fourier transformed infrared spectroscopy (FT-IR). Additionally, air samples from 12 further households, were analysed by scanning electron microscopy (SEM) to evaluate particle structure and silica content. The majority (89%) of household air samples had undetectable quartz levels (quartz in smoky coal went on to form part of the ash. These findings indicate that the quartz within smoky coal does not become adequately airborne during the combustion process to cause significant lung cancer risk, instead going on to form part of the ash. The identification of fibre-like particles in air samples is an interesting finding, although the clinical relevance of this finding remains unclear. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Additive surface complexation modeling of uranium(VI) adsorption onto quartz-sand dominated sediments.

    Science.gov (United States)

    Dong, Wenming; Wan, Jiamin

    2014-06-17

    Many aquifers contaminated by U(VI)-containing acidic plumes are composed predominantly of quartz-sand sediments. The F-Area of the Savannah River Site (SRS) in South Carolina (USA) is an example. To predict U(VI) mobility and natural attenuation, we conducted U(VI) adsorption experiments using the F-Area plume sediments and reference quartz, goethite, and kaolinite. The sediments are composed of ∼96% quartz-sand and 3-4% fine fractions of kaolinite and goethite. We developed a new humic acid adsorption method for determining the relative surface area abundances of goethite and kaolinite in the fine fractions. This method is expected to be applicable to many other binary mineral pairs, and allows successful application of the component additivity (CA) approach based surface complexation modeling (SCM) at the SRS F-Area and other similar aquifers. Our experimental results indicate that quartz has stronger U(VI) adsorption ability per unit surface area than goethite and kaolinite at pH ≤ 4.0. Our modeling results indicate that the binary (goethite/kaolinite) CA-SCM under-predicts U(VI) adsorption to the quartz-sand dominated sediments at pH ≤ 4.0. The new ternary (quartz/goethite/kaolinite) CA-SCM provides excellent predictions. The contributions of quartz-sand, kaolinite, and goethite to U(VI) adsorption and the potential influences of dissolved Al, Si, and Fe are also discussed.

  11. Respirable quartz exposure on two medium-sized farms in southern Mozambique.

    Science.gov (United States)

    Franque Mirembo, José C; Swanepoel, Andrew J; Rees, David

    2013-01-01

    Little is known about the potential for overexposure to respirable quartz in farming, in most parts of the world. To measure respirable dust and quartz exposure of tractor operators on two medium-sized dry climate farms. This is a descriptive cross-sectional study of dust exposure of four tractor operators. Farms were selected by convenience sampling. The MDHS 14/3 and FTIR MDHS 101 HSE methods were used to measure dust and to analyze the mass of quartz in dust, respectively. Seventy respirable dust measurements were done. Respirable dust and quartz ranged from 0·01 to 2·88 and 0·001 to 0·30 mg/m(3), respectively. All operators had at least one respirable quartz exposure above 0·1 mg/m(3). Only 17% of respirable quartz concentrations were lower than the ACGIH TLV of 0·025 mg/m(3). The potential for overexposure to respirable quartz was demonstrated. There was a great deal of exposure variability on these farms which has implications for sampling strategies for dust in farming.

  12. Arsenic removal from water using natural iron mineral-quartz sand columns.

    Science.gov (United States)

    Guo, Huaming; Stüben, Doris; Berner, Zolt

    2007-05-15

    The study has investigated the feasibility of using siderite-coated quartz sand and/or hematite-coated quartz sand columns for removing As from water. Arsenic-spiked tap water and synthetic As solution with As concentrations from 200 to 500 mug/L were used for the experiments. Since three coating methods employed to prepare siderite-coated quartz sand and hematite-coated quartz sand had no significant impact on As adsorption in batch tests, the column fillings were produced by means of the simplest one involving mechanically mixing the Fe mineral with quartz sand. Fixed bed tests show that the combination of siderite-coated quartz sand and hematite-coated quartz sand greatly promoted the column performance in removing As and the presence of As(III) in the influent improved the removal efficiency of the column. The relatively low capacity in treating As-spiked tap water arose from the suppression of FeCO(3) dissolution in the presence of high HCO(3)(-) concentration (333 mg/L), which consequently limited the formation of fresh Fe(III) oxides. However, the H(2)O(2)-conditioning greatly increased As adsorption capacity of the column for remediating As-spiked tap water. The Toxicity Characteristic Leaching Procedure (TCLP) test shows that the spent adsorbents were not hazardous and could be safely disposed of to landfill.

  13. Sedimentary differentiation of aeolian grains at the White Sands National Monument, New Mexico, USA

    Science.gov (United States)

    Fenton, Lori K.; Bishop, Janice L.; King, Sara; Lafuente, Barbara; Horgan, Briony; Bustos, David; Sarrazin, Philippe

    2017-06-01

    weaker than this value would not lift the large grains into differentiation-inducing saltation, whereas the observed differentiated trend would be obliterated by significantly stronger winds. When applied to Olympia Undae, a similar sediment flux analysis suggests that the strongest winds modeled by the Mars Climate Database (MCD) are consistent with the observed concentration of gypsum at dune crests. Density-driven differentiation in transport should not influence sediment fluxes of finer grains (<1 mm) as strongly on Earth, suggesting that the high ratio of fine gypsum grains to other minerals at WSNM is caused by a relatively high production and/or abrasion rate of gypsum sand. The observed preferential transport of coarse-grained gypsum in the dune field conceals a broader range of coarse-grained minerals present on Alkali Flat, contributing to the problem that mineralogy determined through both remote sensing of dune fields and analysis of dune foresets does not fully represent that of the source regions. Unlike quartz, the concentration of gypsum in WSNM occurs not because it is more resistant to weathering and erosion than other minerals, but rather because it is more readily produced (in the case of finer grains) and transported (in the case of coarser grains) than other minerals present in the region.

  14. Pesticides Use among Grain Merchants in Mubi Grain Markets of ...

    African Journals Online (AJOL)

    It is, therefore, recommended that farmers, retailers, distributors and all the pesticide workers should undergo regular training/workshop on the use and safety measures of pesticides. Also multimedia awareness activities in local language should be massively conducted. Key words: Pesticides, food security, grain merchants ...

  15. Why Is It Important to Eat Grains, Especially Whole Grains?

    Science.gov (United States)

    ... and folate), and minerals ( iron , magnesium , and selenium). Dietary fiber from whole grains or other foods, may help reduce blood cholesterol levels and may lower risk of heart disease, obesity, and type 2 diabetes. Fiber is important for proper bowel function. It ...

  16. Thermoluminescence response of natural white quartz collected from Gelephu, Bhutan

    Science.gov (United States)

    Kalita, J. M.; Wary, G.

    2016-09-01

    TL properties of natural quartz mineral collected from Gelephu, (Bhutan) were studied. With the help of various characterization techniques the quality of the sample was tested. The thermoluminescence (TL) analysis was carried out under X-ray irradiation. The un-irradiated sample showed no TL signal; however, after X-ray irradiation, a composite glow curve was observed. The kinetic analysis of the glow curve was carried out and it was observed that there was five trapping sites at depths ∼0.68, 0.90, 0.97, 1.06 and 1.10 eV responsible for five closely spaced glow peaks at ∼341, 362, 383, 397 and 426 K respectively. The dosimetric features of the mineral were studied. The response when studied from the whole glow curve was non-linear. However, the dose response studied from the 426 K peak was found to be linear from 10 mGy to 10 Gy. The fading of the TL signal of this 426 K peak was ∼12% within 5 days after irradiation and onward it was ∼4% up to 30 days. The reproducibility of the results was also good.

  17. Acoustic Tests of Lorentz Symmetry Using Quartz Oscillators

    Directory of Open Access Journals (Sweden)

    Anthony Lo

    2016-02-01

    Full Text Available We propose and demonstrate a test of Lorentz symmetry based on new, compact, and reliable quartz oscillator technology. Violations of Lorentz invariance in the matter and photon sector of the standard model extension generate anisotropies in particles’ inertial masses and the elastic constants of solids, giving rise to measurable anisotropies in the resonance frequencies of acoustic modes in solids. A first realization of such a “phonon-sector” test of Lorentz symmetry using room-temperature stress-compensated-cut crystals yields 120 h of data at a frequency resolution of 2.4×10^{−15} and a limit of c[over ˜]_{Q}^{n}=(−1.8±2.2×10^{−14}  GeV on the most weakly constrained neutron-sector c coefficient of the standard model extension. Future experiments with cryogenic oscillators promise significant improvements in accuracy, opening up the potential for improved limits on Lorentz violation in the neutron, proton, electron, and photon sector.

  18. Dedicated finite elements for electrode thin films on quartz resonators.

    Science.gov (United States)

    Srivastava, Sonal A; Yong, Yook-Kong; Tanaka, Masako; Imai, Tsutomu

    2008-08-01

    The accuracy of the finite element analysis for thickness shear quartz resonators is a function of the mesh resolution; the finer the mesh resolution, the more accurate the finite element solution. A certain minimum number of elements are required in each direction for the solution to converge. This places a high demand on memory for computation, and often the available memory is insufficient. Typically the thickness of the electrode films is very small compared with the thickness of the resonator itself; as a result, electrode elements have very poor aspect ratios, and this is detrimental to the accuracy of the result. In this paper, we propose special methods to model the electrodes at the crystal interface of an AT cut crystal. This reduces the overall problem size and eliminates electrode elements having poor aspect ratios. First, experimental data are presented to demonstrate the effects of electrode film boundary conditions on the frequency-temperature curves of an AT cut plate. Finite element analysis is performed on a mesh representing the resonator, and the results are compared for testing the accuracy of the analysis itself and thus validating the results of analysis. Approximations such as lumping and Guyan reduction are then used to model the electrode thin films at the electrode interface and their results are studied. In addition, a new approximation called merging is proposed to model electrodes at the electrode interface.

  19. Quantitative study of protein-protein interactions by quartz nanopipettes.

    Science.gov (United States)

    Tiwari, Purushottam Babu; Astudillo, Luisana; Miksovska, Jaroslava; Wang, Xuewen; Li, Wenzhi; Darici, Yesim; He, Jin

    2014-09-07

    In this report, protein-modified quartz nanopipettes were used to quantitatively study protein-protein interactions in attoliter sensing volumes. As shown by numerical simulations, the ionic current through the conical-shaped nanopipette is very sensitive to the surface charge variation near the pore mouth. With the appropriate modification of negatively charged human neuroglobin (hNgb) onto the inner surface of a nanopipette, we were able to detect concentration-dependent current change when the hNgb-modified nanopipette tip was exposed to positively charged cytochrome c (Cyt c) with a series of concentrations in the bath solution. Such current change is due to the adsorption of Cyt c to the inner surface of the nanopipette through specific interactions with hNgb. In contrast, a smaller current change with weak concentration dependence was observed when Cyt c was replaced with lysozyme, which does not specifically bind to hNgb. The equilibrium dissociation constant (KD) for the Cyt c-hNgb complex formation was derived and the value matched very well with the result from surface plasmon resonance measurement. This is the first quantitative study of protein-protein interactions by a conical-shaped nanopore based on charge sensing. Our results demonstrate that nanopipettes can potentially be used as a label-free analytical tool to quantitatively characterize protein-protein interactions.

  20. Quartz Microbalance Sensor for the Detection of Acrylamide

    Directory of Open Access Journals (Sweden)

    Christoph A. Schalley

    2004-10-01

    Full Text Available Abstract: Several macrocycles of the Hunter-Vögtle type have been identified as superior host compounds for the detection of small amounts of acrylamide. When coated onto the surface of a quartz microbalance, these compounds serve as highly sensitive and selective sensor-active layers for their use in electronic noses. In this study, differently substituted macrocycles were investigated including an open-chain analogue and a catenane. Their structure and functional groups are correlated with their observed affinities to acrylamide and related acids and amides. The much smaller response of the open-chain compound and the almost absent sensor response of the catenane suggest that binding occurs within the cavity of the macrocycle. Theoretical calculations agree well with the experimental data even though they do not yet take into account the arrangement of the macrocycles in the sensor-active layer. The lower detection limit of acrylamide is 10 parts per billion (ppb, which is impressively low for this type of sensor. Other related compounds such as acrylic acid, propionamide, or propionic acid show no or significantly lower affinities to the macrocycles in these concentration ranges.

  1. Progresses on the theory and application of quartz crystal microbalance

    Science.gov (United States)

    Qiao, Xiaoxi; Zhang, Xiangjun; Tian, Yu; Meng, Yonggang

    2016-09-01

    Quartz crystal microbalance (QCM) is a nondestructive technique in investigating the physical properties of solid-liquid interfacial layer in situ. It has the capability of quantifying the extremely tiny force change occurring on the interface by measuring the frequency shift Δ f and the energy dissipation change Δ D (or the half-bandwidth variation Δ Γ ). The quantitative analysis of QCM results greatly depends on the theoretical models, whose development could generally expand the comprehension of the properties at the interfaces and the application of QCM. In the paper, the progresses on the theory and applications of QCM are reviewed. The commonly used theoretical models for a single layer in the gas/liquid phase are essential for QCM in the fields of biosensor application, surface chemistry study, and interfacial rheology, such as the adsorption of proteins, the polymer and surfactants, and the viscoelastic properties of the interfacial liquid layer. The advanced models, incorporating the effects of boundary slip, surface roughness, microstructure, and micro/nanoscale confinement, are helpful for a better understanding and description of how these factors influence the various interfacial processes occurring on the solid-liquid interface, e.g., interfacial rheology and adsorption. The establishments of nanocell and the corresponding theoretical model make QCM a potential technique in studying the dynamic behavior of micro/nanoscale flow coupling with various surface effects by connecting a micro/nanofluidic channel to the nanocell.

  2. Molecular Imprinting Technology in Quartz Crystal Microbalance (QCM Sensors

    Directory of Open Access Journals (Sweden)

    Sibel Emir Diltemiz

    2017-02-01

    Full Text Available Molecularly imprinted polymers (MIPs as artificial antibodies have received considerable scientific attention in the past years in the field of (biosensors since they have unique features that distinguish them from natural antibodies such as robustness, multiple binding sites, low cost, facile preparation and high stability under extreme operation conditions (higher pH and temperature values, etc.. On the other hand, the Quartz Crystal Microbalance (QCM is an analytical tool based on the measurement of small mass changes on the sensor surface. QCM sensors are practical and convenient monitoring tools because of their specificity, sensitivity, high accuracy, stability and reproducibility. QCM devices are highly suitable for converting the recognition process achieved using MIP-based memories into a sensor signal. Therefore, the combination of a QCM and MIPs as synthetic receptors enhances the sensitivity through MIP process-based multiplexed binding sites using size, 3D-shape and chemical function having molecular memories of the prepared sensor system toward the target compound to be detected. This review aims to highlight and summarize the recent progress and studies in the field of (biosensor systems based on QCMs combined with molecular imprinting technology.

  3. TL estimation of paleodose of dune-sand quartz

    Science.gov (United States)

    Franklin, A. D.; Hornyak, W. F.; Dickerson, W.

    Archeological quartz exhibits two major TL peaks. At a ramp rate of 1°C/sec one (RBP) occurs at ˜380 nm and ˜290°C and bleaches very rapidly when exposed to light across the visible spectrum. The other (SBP) occurs at ˜480 nm, at ˜330°C and bleaches, when exposed to UV light, much more slowly. The 290°C peak can be isolated using a UV filter (e.g. Schott UG11) and a subtraction technique, and can be used to estimate the paleodose with the regeneration method. The 330°C peak can be isolated with a green (e.g. Chance OGr1) or yellow (e.g. Schott GG-475) filter and might be used to estimate the paleodose with the R-F technique. Measurements of first and second (after optical bleaching) glow growth curves suggest the SBP may not conform to the assumptions of the R-F method, and use of the RBP may require at least approximate reproduction of the solar exposure at the time of burial.

  4. Quartz Crystal Microbalance Electronic Interfacing Systems: A Review

    Directory of Open Access Journals (Sweden)

    Abdulrahman Alassi

    2017-12-01

    Full Text Available Quartz Crystal Microbalance (QCM sensors are actively being implemented in various fields due to their compatibility with different operating conditions in gaseous/liquid mediums for a wide range of measurements. This trend has been matched by the parallel advancement in tailored electronic interfacing systems for QCM sensors. That is, selecting the appropriate electronic circuit is vital for accurate sensor measurements. Many techniques were developed over time to cover the expanding measurement requirements (e.g., accommodating highly-damping environments. This paper presents a comprehensive review of the various existing QCM electronic interfacing systems. Namely, impedance-based analysis, oscillators (conventional and lock-in based techniques, exponential decay methods and the emerging phase-mass based characterization. The aforementioned methods are discussed in detail and qualitatively compared in terms of their performance for various applications. In addition, some theoretical improvements and recommendations are introduced for adequate systems implementation. Finally, specific design considerations of high-temperature microbalance systems (e.g., GaPO4 crystals (GCM and Langasite crystals (LCM are introduced, while assessing their overall system performance, stability and quality compared to conventional low-temperature applications.

  5. Quartz crystal microbalance sensor using ionophore for ammonium ion detection.

    Science.gov (United States)

    Kosaki, Yasuhiro; Takano, Kosuke; Citterio, Daniel; Suzuki, Koji; Shiratori, Seimei

    2012-01-01

    Ionophore-based quartz crystal microbalance (QCM) ammonium ion sensors with a detection limit for ammonium ion concentrations as low as 2.2 microM were fabricated. Ionophores are molecules, which selectively bind a particular ion. In this study, one of the known ionophores for ammonium, nonactin, was used to detect ammonium ions for environmental in-situ monitoring of aquarium water for the first time. To fabricate the sensing films, poly(vinyl chloride) was used as the matrix for the immobilization of nonactin. Furthermore, the anionic additive, tetrakis (4-chlorophenyl) borate potassium salt and the plasticizer dioctyl sebacate were used to enhance the sensor properties. The sensor allowed detecting ammonium ions not only in static solution, but also in flowing water. The sensor showed a nearly linear response with the increase of the ammonium ion concentration. The QCM resonance frequency increased with the increase of ammonium ion concentration, suggesting a decreasing weight of the sensing film. The detailed response mechanism could not be verified yet. However, from the results obtained when using a different plasticizer, nitrophenyl octyl ether, it is considered that this effect is caused by the release of water molecules. Consequently, the newly fabricated sensor detects ammonium ions by discharge of water. It shows high selectivity over potassium and sodium ions. We conclude that the newly fabricated sensor can be applied for detecting ammonium ions in aquarium water, since it allows measuring low ammonium ion concentrations. This sensor will be usable for water quality monitoring and controlling.

  6. Effect of grain-coating mineralogy on nitrate and sulfate storage in the unsaturated zone

    Science.gov (United States)

    Reilly, T.J.; Fishman, N.S.; Baehr, A.L.

    2009-01-01

    Unsaturated-zone sediments and the chemistry of shallow groundwater underlying a small (???8-km2) watershed were studied to identify the mechanisms responsible for anion storage within the Miocene Bridgeton Formation and weathered Coastal Plain deposits in southern New Jersey. Lower unsaturated-zone sediments and shallow groundwater samples were collected and concentrations of selected ions (including NO3- and SO42-) from 11 locations were determined. Grain size, sorting, and color of the lower unsaturated-zone sediments were determined and the mineralogy of these grains and the composition of coatings were analyzed by petrographic examination, scanning electron microscopy and energy dispersive analysis of x-rays, and quantitative whole-rock x-ray diffraction. The sediment grains, largely quartz and chert (80-94% w/w), are coated with a very fine-grained (<20 ??m), complex mixture of kaolinite, halloysite, goethite, and possibly gibbsite and lepidocrocite. The mineral coatings are present as an open fabric, resulting in a large surface area in contact with pore water. Significant correlations between the amount of goethite in the grain coatings and the concentration of sediment-bound SO42- were observed, indicative of anion sorption. Other mineral-chemical relations indicate that negatively charged surfaces and competition with SO 42- results in exclusion of NO3- from inner sphere exchange sites. The observed NO3- storage may be a result of matrix forces within the grain coatings and outer sphere complexation. The results of this study indicate that the mineralogy of grain coatings can have demonstrable effects on the storage of NO 3- and SO42- in the unsaturated zone. ?? Soil Science Society of America. All rights reserved.

  7. Testing the application of quartz and feldspar luminescence dating to MIS 5 Japanese marine deposits

    DEFF Research Database (Denmark)

    Thiel, Christine; Tsukamoto, Sumiko; Tokuyasu, Kayoko

    2015-01-01

    The applicability of both quartz and feldspar luminescence dating was tested on twenty-five samples from a marine succession now forming a coastal cliff at Oga Peninsula, Honshu Island, Japan. The quartz optically stimulated luminescence (OSL) signal shows thermal instability and linear modulated...... (LM)-OSL analysis revealed the dominance of a slow component. When compared with independent age control provided by two marker tephras, the quartz OSL ages grossly underestimate the depositional age. In contrast, potassium (K)-rich feldspar is a suitable dosimeter when measured using post-IR infrared...

  8. Modelling the thermal quenching mechanism in quartz based on time-resolved optically stimulated luminescence

    DEFF Research Database (Denmark)

    Pagonis, V.; Ankjærgaard, Christina; Murray, Andrew

    2010-01-01

    This paper presents a new numerical model for thermal quenching in quartz, based on the previously suggested Mott–Seitz mechanism. In the model electrons from a dosimetric trap are raised by optical or thermal stimulation into the conduction band, followed by an electronic transition from...... simulations are carried out of time-resolved optically stimulated luminescence (TR-OSL) experiments, in which the temperature dependence of luminescence lifetimes in quartz is studied as a function of the stimulation temperature. Good quantitative agreement is found between the simulation results and new...... experimental data obtained using a single-aliquot procedure on a sedimentary quartz sample....

  9. Using optically stimulated electrons from quartz for the estimation of natural doses

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Murray, A.S.; Denby, Phil M.

    2009-01-01

    quartz samples are studied to examine the possible use of OSE as a chronometer. First the relative variability in OSE and OSL growth curve shapes and the effect of preheat on these are presented, and from these curves, conclusions are drawn concerning the charge movement in natural quartz. Secondly...... dose using the single-aliquot regenerative-dose (SAR) procedure. Finally, a comparative study of the equivalent doses estimated using both OSE and OSL from 10 quartz samples are presented, and it is shown that OSE has a significant potential in retrospective dosimetry....

  10. Luminescence property of volcanic quartz and the use of red isothermal TL for dating tephras

    DEFF Research Database (Denmark)

    Tsukamoto, S.; Murray, A.S.; Huot, S.

    2007-01-01

    An optically stimulated luminescence (OSL) age obtained from a Japanese tephra using quartz phenocrysts severely underestimated the known age. The characteristics of the OSL signals were investigated in order to understand the cause of the underestimation; the main OSL component of volcanic quartz...... gave an age consistent with the independent age. Furthermore, red isothermal TL (RITL) at 380 degrees C allowed the RTL signal to be separated from to the thermal background, and RITL ages of three volcanic quartz samples show good agreement with independent ages. (C) 2006 Elsevier Ltd. All rights...

  11. 75 FR 81965 - Grain Inspection Advisory Committee Reestablishment

    Science.gov (United States)

    2010-12-29

    ... Grain Inspection, Packers and Stockyards Administration Grain Inspection Advisory Committee Reestablishment AGENCY: Grain Inspection, Packers and Stockyards Administration, USDA. ACTION: Notice to... Grain Inspection, Packers and Stockyards Administration (GIPSA) Grain Inspection Advisory Committee...

  12. The ongoing search for the oldest rock on the Danish island of Bornholm: new U-Pb zircon ages for a quartz-rich xenolith and country rock from the Svaneke Granite

    DEFF Research Database (Denmark)

    Waight, Tod Earle; Serre, Simon H.; Næsby, Sebastian H.

    2017-01-01

    Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine-grained and qu......Previous geochronological studies on the Danish island of Bornholm have not identified any rocks older than c. 1.46 Ga. New LA-ICP-MS U-Pb zircon ages are presented for a xenolith within, and the country rock gneiss adjacent to, the Svaneke Granite on Bornholm. The xenolith is fine......-grained and quartz-rich and was likely derived from either a quartz-rich sedimentary protolith or a hydrothermally altered felsic volcanic rock. The relatively fine-grained felsic nature of the country rock gneiss and the presence of large zoned feldspars that may represent phenocrysts suggest its protolith may have...... been a felsic volcanic or shallow intrusive rock. A skarn-like inclusion from a nearby locality likely represents an originally carbonate sediment and is consistent with supracrustal rocks being present at least locally. Zircon data from the xenolith define an upper intercept age of 1483 ± 12 Ma (2σ...

  13. NUTRITIONAL CHARACTERIZATION OF GRAIN AMARANTH ...

    African Journals Online (AJOL)

    IBUKUN

    season. With a toasted flavor similar to popcorn when cooked, amaranth seeds are small in size but a good source of carbohydrate and protein (15-17 percent by weight). It is rich in the amino acids methionine, cycteine and has the highest content of lysine compared with all grains. It also has three times the fiber of wheat.

  14. Concepts on Low Temperature Mechanical Grain Growth

    Energy Technology Data Exchange (ETDEWEB)

    Sharon, John Anthony [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.; Boyce, Brad Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Metallurgy and Materials Joining Dept.

    2013-11-01

    In metals, as grain size is reduced below 100nm, conventional dislocation plasticity is suppressed resulting in improvements in strength, hardness, and wears resistance. Existing and emerging components use fine grained metals for these beneficial attributes. However, these benefits can be lost in service if the grains undergo growth during the component’s lifespan. While grain growth is traditionally viewed as a purely thermal process that requires elevated temperature exposure, recent evidence shows that some metals, especially those with nanocrystalline grain structure, can undergo grain growth even at room temperature or below due to mechanical loading. This report has been assembled to survey the key concepts regarding how mechanical loads can drive grain coarsening at room temperature and below. Topics outlined include the atomic level mechanisms that facilitate grain growth, grain boundary mobility, and the impact of boundary structure, loading scheme, and temperature.

  15. Compact all-fiber quartz-enhanced photoacoustic spectroscopy sensor with a 30.72 kHz quartz tuning fork and spatially resolved trace gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yufei, E-mail: mayufei@hit.edu.cn [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001 (China); Post-doctoral Mobile Station of Power Engineering and Engineering Thermophysics, Harbin Institute of Technology, Harbin 150001 (China); He, Ying; Yu, Xin; Zhang, Jingbo [National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001 (China); Sun, Rui [Post-doctoral Mobile Station of Power Engineering and Engineering Thermophysics, Harbin Institute of Technology, Harbin 150001 (China); Tittel, Frank K. [Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, Texas 77005 (United States)

    2016-02-29

    An ultra compact all-fiber quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor using quartz tuning fork (QTF) with a low resonance frequency of 30.72 kHz was demonstrated. Such a sensor architecture has the advantages of easier optical alignment, lower insertion loss, lower cost, and more compact compared with a conventional QEPAS sensor using discrete optical components for laser delivery and coupling to the QTF. A fiber beam splitter and three QTFs were employed to perform multi-point detection and demonstrated the potential of spatially resolved measurements.

  16. Compact all-fiber quartz-enhanced photoacoustic spectroscopy sensor with a 30.72 kHz quartz tuning fork and spatially resolved trace gas detection

    Science.gov (United States)

    Ma, Yufei; He, Ying; Yu, Xin; Zhang, Jingbo; Sun, Rui; Tittel, Frank K.

    2016-02-01

    An ultra compact all-fiber quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor using quartz tuning fork (QTF) with a low resonance frequency of 30.72 kHz was demonstrated. Such a sensor architecture has the advantages of easier optical alignment, lower insertion loss, lower cost, and more compact compared with a conventional QEPAS sensor using discrete optical components for laser delivery and coupling to the QTF. A fiber beam splitter and three QTFs were employed to perform multi-point detection and demonstrated the potential of spatially resolved measurements.

  17. Quantitative study of protein-protein interactions by quartz nanopipettes

    Science.gov (United States)

    Tiwari, Purushottam Babu; Astudillo, Luisana; Miksovska, Jaroslava; Wang, Xuewen; Li, Wenzhi; Darici, Yesim; He, Jin

    2014-08-01

    In this report, protein-modified quartz nanopipettes were used to quantitatively study protein-protein interactions in attoliter sensing volumes. As shown by numerical simulations, the ionic current through the conical-shaped nanopipette is very sensitive to the surface charge variation near the pore mouth. With the appropriate modification of negatively charged human neuroglobin (hNgb) onto the inner surface of a nanopipette, we were able to detect concentration-dependent current change when the hNgb-modified nanopipette tip was exposed to positively charged cytochrome c (Cyt c) with a series of concentrations in the bath solution. Such current change is due to the adsorption of Cyt c to the inner surface of the nanopipette through specific interactions with hNgb. In contrast, a smaller current change with weak concentration dependence was observed when Cyt c was replaced with lysozyme, which does not specifically bind to hNgb. The equilibrium dissociation constant (KD) for the Cyt c-hNgb complex formation was derived and the value matched very well with the result from surface plasmon resonance measurement. This is the first quantitative study of protein-protein interactions by a conical-shaped nanopore based on charge sensing. Our results demonstrate that nanopipettes can potentially be used as a label-free analytical tool to quantitatively characterize protein-protein interactions.In this report, protein-modified quartz nanopipettes were used to quantitatively study protein-protein interactions in attoliter sensing volumes. As shown by numerical simulations, the ionic current through the conical-shaped nanopipette is very sensitive to the surface charge variation near the pore mouth. With the appropriate modification of negatively charged human neuroglobin (hNgb) onto the inner surface of a nanopipette, we were able to detect concentration-dependent current change when the hNgb-modified nanopipette tip was exposed to positively charged cytochrome c (Cyt c) with

  18. Fluoride retardation from quartz sand-packed column tests

    Directory of Open Access Journals (Sweden)

    Eduardo Usunoff

    2009-06-01

    Full Text Available Inasmuch as both low and high concentrations of F- in groundwater have different detrimental effects on human health (increased dental caries, and mottled enamel or even severe structural bone deformations, respectively, many efforts have focused on the movement of such anion in aqueous systems. It is so because water drinking is the main intake of F- by humans. This paper presents the results of seven dynamic experiments in which solutions of varying [F-], pH, and flow velocities circulated through columns packed with clean quartz sand. The breakthrough data were analyzed by means of a computer code adapted to the estimation of equilibrium and non-equilibrium solute transport parameters from miscible displacement experiments in a steady-state, uniform flow field using a pulse-type or continuous source. It was found that larger retardation factors (R are associated with low pH, low [F-] in the feed solutions, and larger flow velocities. Such results appear to be related to the form of the F species, the rather weak bond between the adsorbate and the quartz sand, and stronger anion repulsion at low pore velocities. The estimated values for R vary between 1,22 and 1,50, whereas the distribution coefficients were in the range of 0,1 to 0,05 L kg-1. It should be said that the breakthrough curves display hysteresis, leading to a desorption behavior that proceeds faster than the adsorption process.Puesto que tanto valores bajos como altos de F- en las aguas subterráneas tienen efectos adversos en la salud de los humanos (mayor cantidad de caries, y manchas del esmalte dental e incluso deformaciones óseas, respectivamente, han sido muchos los esfuerzos destinados a dilucidar el movimiento de especies fluoradas en ambientes acuosos. Ello es así porque el consumo de agua por parte de seres humanos representa la mayor fuente de ingreso de F-. Este trabajo presenta los resultados de siete experimentos dinámicos en los que soluciones de diferentes [F

  19. Retrospective dosimetry using Japanese brick quartz: A way forward despite an unstable fast decaying OSL signal

    DEFF Research Database (Denmark)

    Fujita, Hiroki; Jain, Mayank; Murray, A.S.

    2011-01-01

    of Japanese brick quartz examined here can be used to derive precise estimates of accident dose, and, possibly to distinguish between sources of gamma radiation in a nuclear accident. To our knowledge, this is the first report on the existence of an unstable fast decaying OSL signal in quartz derived from......Quartz extracted from heated bricks has been previously suggested for use in dose estimation in accident dosimetry, but this technique has never been applied before to Japanese quartz which often has unusual OSL characteristics. In this study the optically stimulated luminescence (OSL...... peak, which necessitates a prior heat treatment. A single-aliquot regenerative-dose (SAR) protocol is developed and tested using thermal treatments intended to isolate a stable dosimetric signal. A minimum detection limit of 65 mGy is then estimated using this protocol. Following irradiation using 60Co...

  20. ANIE: A Mathematical Algorithm for Automated Indexing of Planar Deformation Features in Shocked Quartz

    Science.gov (United States)

    Huber, M. S.; Ferrière, L.; Losiak, A.; Koeberl, C.

    2011-03-01

    A mathematical method of indexing planar deformation features in quartz and a Microsoft Excel macro for automated indexing is presented, allowing for more rapid and accurate results than the previously used manual method.

  1. Fast three-step method for shear moduli calculation from quartz crystal resonator measurements.

    Science.gov (United States)

    Behling, C; Lucklum, R; Hauptmann, P

    1999-01-01

    Quartz crystal resonator measurements can be used for polymer material characterization. The non-gravimetric regime of these resonators is exploited: the electrical response of polymer-coated quartz resonators depends on the polymer shear modulus. Previously reported methods employ an electrical admittance analysis together with difficult and time-consuming data fitting procedures to calculate the film shear modulus. This contribution presents a fast and accurate three-step method for the calculation of complex shear moduli of polymer films from quartz crystal resonator measurements. In the first step, the acoustic load impedance is calculated from the electrical admittance of the quartz crystal. The key point of this method is the application of a family of approximations for the calculation of the shear modulus from the acoustic load impedance in the second step. In the third step, the best approximation is improved further in an iterative procedure.

  2. The Suitability Of Local Quartz Sand In The Production Of Bath Crucibles

    National Research Council Canada - National Science Library

    C. O. Okpanachi; S. I. Ibrahim; A. C. Okoro; K. Dogo; M. K. Idris

    2015-01-01

    The suitability of local quartz sand in the production of bath crucibles is a study that was carried out in order to impart overall strength on bath crucibles hence reduce breakages during fettling...

  3. Quartz Knapping Strategies in the Howiesons Poort at Sibudu (KwaZulu-Natal, South Africa)

    Science.gov (United States)

    de la Peña, Paloma; Wadley, Lyn

    2014-01-01

    The variability associated with Sibudu's Howiesons Poort Industry highlights the unpredictable trajectory of technology in the Middle Stone Age. We reach this conclusion through a study of the technology on quartz from one of the Howiesons Poort layers (Grey Sand) from Sibudu rock shelter. Quartz bifacial technology has previously been described at the site, but this new in-depth study of the quartz technology reveals other strategies. First is the recurring employment of bipolar knapping, formerly considered as a defining feature of the Later Stone Age. Secondly, we highlight a laminar technology with emphasis on small quartz bladelets. Bipolar cores are most common, followed by prismatic cores. The knapping strategies in Grey Sand seem to involve systematic recycling and the deliberate production of microliths. PMID:25014352

  4. Contamination-free graphene by chemical vapor deposition in quartz furnaces

    National Research Council Canada - National Science Library

    Nicola Lisi; Theodoros Dikonimos; Francesco Buonocore; Martina Pittori; Raffaello Mazzaro; Rita Rizzoli; Sergio Marras; Andrea Capasso

    2017-01-01

    .... When graphene is grown in quartz furnaces, in particular, it is common to end up with samples contaminated by heterogeneous particles, which alter the growth mechanism and affect graphene’s properties...

  5. Quantitative Classification of Quartz by Laser Induced Breakdown Spectroscopy in Conjunction with Discriminant Function Analysis

    Directory of Open Access Journals (Sweden)

    A. Ali

    2016-01-01

    Full Text Available A responsive laser induced breakdown spectroscopic system was developed and improved for utilizing it as a sensor for the classification of quartz samples on the basis of trace elements present in the acquired samples. Laser induced breakdown spectroscopy (LIBS in conjunction with discriminant function analysis (DFA was applied for the classification of five different types of quartz samples. The quartz plasmas were produced at ambient pressure using Nd:YAG laser at fundamental harmonic mode (1064 nm. We optimized the detection system by finding the suitable delay time of the laser excitation. This is the first study, where the developed technique (LIBS+DFA was successfully employed to probe and confirm the elemental composition of quartz samples.

  6. The Quartz-Crystal Microbalance in an Undergraduate Laboratory Experiment: I. Fundamentals and Instrumentation

    Science.gov (United States)

    Tsionsky, Vladimir

    2007-01-01

    The fundamentals, as well as the instrumentation of the quartz-crystal microbalance (QCM) technique that is used in an undergraduate laboratory experiment are being described. The QCM response can be easily used to change the properties of any system.

  7. Installation and evaluation of weigh-in-motion utilizing quartz-piezo sensor technology.

    Science.gov (United States)

    2016-06-28

    The objective of the research study was: to install a quartz-piezo based WIM system, and to : determine sensor survivability, accuracy and reliability under actual traffic conditions in : Connecticuts environment. If the systems prove dependable a...

  8. Comparative Petrographic Maturity of River and Beach Sand, and Origin of Quartz Arenites.

    Science.gov (United States)

    Ferree, Rob A.; And Others

    1988-01-01

    Describes a deterministic computer model that incorporates: (1) initial framework composition; (2) abrasion factors for quartz, feldspar, and rock fragments; and (3) a fragmentation ratio for rock fragments to simulate the recycling of coastal sands by rivers and beaches. (TW)

  9. Bacterial attachment and detachment in aluminum-coated quartz sand in response to ionic strength change.

    Science.gov (United States)

    Lee, Chang-Gu; Park, Seong-Jik; Han, Yong-Un; Park, Jeong-Ann; Kim, Song-Bae

    2010-06-01

    Column experiments were performed to investigate the effect of ionic strength on the attachment and detachment of Staphylococcus aureus ATCC 10537 and Bacillus subtilis ATCC 6633 in aluminum-coated quartz sand. Results showed that the average mass recovery decreased from 80.7 to 45.3% in quartz sand and remained constant in aluminum-coated sand with increasing ionic concentrations of sodium chloride solution from 1 to 100 mmol/L. As the ionic concentrations of leaching solution changed from 100 to 0.1 mmol/L, average mass recovery of 39.1% was obtained from quartz sand (bacterial release), but no detachment was observed from aluminum-coated sand. This lack of detachment can be attributed to inner-sphere complexes between bacteria and aluminum-coated sand, which are minimally affected by ionic strength. This research indicates that aluminum-coated sand has advantages over quartz sand in bacteria removal in water filtration systems.

  10. Quartz knapping strategies in the Howiesons Poort at Sibudu (KwaZulu-Natal, South Africa.

    Directory of Open Access Journals (Sweden)

    Paloma de la Peña

    Full Text Available The variability associated with Sibudu's Howiesons Poort Industry highlights the unpredictable trajectory of technology in the Middle Stone Age. We reach this conclusion through a study of the technology on quartz from one of the Howiesons Poort layers (Grey Sand from Sibudu rock shelter. Quartz bifacial technology has previously been described at the site, but this new in-depth study of the quartz technology reveals other strategies. First is the recurring employment of bipolar knapping, formerly considered as a defining feature of the Later Stone Age. Secondly, we highlight a laminar technology with emphasis on small quartz bladelets. Bipolar cores are most common, followed by prismatic cores. The knapping strategies in Grey Sand seem to involve systematic recycling and the deliberate production of microliths.

  11. Quartz crystal microbalance biosensor for rapid detection of aerosolized microorganisms

    Science.gov (United States)

    Farka, Zdenĕk.; Kovár, David; Skládal, Petr

    2015-05-01

    Biological warfare agents (BWAs) represent the current menace of the asymmetric war. The early detection of BWAs, especially in the form of bioaerosol, is a challenging task for governments all around the world. Label-free quartz crystal microbalance (QCM) immunosensor and electrochemical immunosensor were developed and tested for rapid detection of BWA surrogate (E. coli) in the form of bioaerosol. Two immobilization strategies for the attachment of antibody were tested; the gold sensor surface was activated by cysteamine and then antibody was covalently linked either using glutaraldehyde, or the reduced antibodies were attached via Sulfo-SMCC. A portable bioaerosol chamber was constructed and used for safe manipulation with aerosolized microorganisms. The dissemination was done using a piezoelectric humidifier, distribution of bioaerosol inside the chamber was ensured using three 12-cm fans. The whole system was controlled remotely using LAN network. The disseminated microbial cells were collected and preconcentrated using the wetted-wall cyclone SASS 2300, the analysis was done using the on-line linked immunosensors. The QCM immunosensor had limit of detection 1×104 CFU·L-1 of air with analysis time 16 min, the whole experiment including dissemination and sensor surface regeneration took 40 min. In case of blank (disseminated sterile buffer), no signal change was observed. The electrochemical immunosensor was able to detect 150 CFU·L-1 of air in 20 min; also in this case, no interferences were observed. Reference measurements were done using particle counter Met One 3400 and by cultivation method on agar plates. The sensors have proved to be applicable for rapid screening of microorganisms in air.

  12. Arsenic Sulfide Nanowire Formation on Fused Quartz Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Olmstead, J.; Riley, B.J.; Johnson, B.R.; Sundaram, S.K.

    2005-01-01

    Arsenic sulfide (AsxSy) nanowires were synthesized by an evaporation-condensation process in evacuated fused quartz ampoules. During the deposition process, a thin, colored film of AsxSy was deposited along the upper, cooler portion of the ampoule. The ampoule was sectioned and the deposited film analyzed using scanning electron microscopy (SEM) to characterize and semi-quantitatively evaluate the microstructural features of the deposited film. A variety of microstructures were observed that ranged from a continuous thin film (warmer portion of the ampoule), to isolated micron- and nano-scale droplets (in the intermediate portion), as well as nanowires (colder portion of the ampoule). Experiments were conducted to evaluate the effects of ampoule cleaning methods (e.g. modify surface chemistry) and quantity of source material on nanowire formation. The evolution of these microstructures in the thin film was determined to be a function of initial pressure, substrate temperature, substrate surface treatment, and initial volume of As2S3 glass. In a set of two experiments where the initial pressure, substrate thermal gradient, and surface treatment were the same, the initial quantity of As2S3 glass per internal ampoule volume was doubled from one test to the other. The results showed that AsxSy nanowires were only formed in the test with the greater initial quantity of As2S3 per internal ampoule volume. The growth data for variation in diameter (e.g. nanowire or droplet) as a function of substrate temperature was fit to an exponential trendline with the form y = Aekx, where y is the structure diameter, A = 1.25×10-3, k = 3.96×10-2, and x is the temperature with correlation coefficient, R2 = 0.979, indicating a thermally-activated process.

  13. Grain surface features and clay mineralogy of the quaternary sediments from Western Deccan Trap Region, India, and their palaeoclimatic significance

    Directory of Open Access Journals (Sweden)

    Veena U. Joshi

    2011-06-01

    Full Text Available Quartz sand grains obtained from a deeply gullied topography along the banks of two tributaries of River Pravara in Maharashtra (India have been examined with a scanning electron microscope (SEM. Quartz grains have been selected after a heavy mineral separation and micro-photographs of each grain were taken at various angles and magnifications. The sediments reveal features resulting from mechanical grinding as well as from chemical alteration. Conchoidal fractures, cleavage planes, grooves, v-shaped indentations etc. are the mechanical features documented on the grains whereas solution pits of varying sizes and intensity, precipitation surfaces, oriented v-pits, solution crevasses and etching are the features of chemical origin. Several evidences indicate that the samples have undergone digenetic changes. Few grains show the features of intense chemical breakdown. The overall assemblages of the grain surface features suggest that the samples have been subjected to subaqueous transport for a considerable period of time. The minor chemical features such as solution pits or semi circular arcuate steps found in abundance on these grains are due to the dissolution of the sediments in a low energy fluviatile environment. For clay mineralogy, fractions between <2 and <0.2 mm were separated out from the sediments. The clay fractions were then subjected to examination by X-ray diffraction (XRD of oriented K/Ca saturated samples using a Philips Diffractometer and Ni-filtered Cu Ka radiation with the scanning speed of 10 2Ө min -1. The main clay minerals for all the samples are identical and show the presence of hydroxy-interlayered smectites with minor quantities of mica, kaolinite, smectites, quartz and feldspar. The first weathering product of the Deccan Basalt (DB is the dioctahedral smectite. Since the present semi aridic climatic condition of the study area can not transform a smectite to HIS and either smectite to kaolin, it is quite likely that

  14. Solution-mass transfer and grain boundary sliding in mafic shear zones - comparison between experiments and nature

    Science.gov (United States)

    Marti, Sina; Heilbronner, Renée; Stünitz, Holger; Plümper, Oliver; Drury, Martyn

    2017-04-01

    Grain size sensitive creep (GSSC) mechanisms are widely recognized to be the most efficient deformation mechanisms in shear zones. With or without initial fracturing and fluid infiltration, the onset of heterogeneous nucleation leading to strong grain size reduction is a frequently described process for the initiation of GSSC. Phase mixing due to reaction and heterogeneous nucleation during GSSC impedes grain growth, sustaining small grain sizes as a prerequisite for GSSC. Here we present rock deformation experiments on 'wet' plagioclase - pyroxene mixtures at T=800°C, P=1.0 and 1.5GPa and strain rates of 2e-5 - 2e-6 1/s, performed with a Griggs-type solid medium deformation apparatus. Microstructural criteria are used to show that both, grain boundary sliding (GBS) and solution-mass transfer processes are active and are interpreted to be the dominant strain accommodating processes. Displacement is localized within shear bands formed by fine-grained ( 300 - 500nm) plagioclase (Pl) and the syn-kinematic reaction products amphibole (Amph), quartz (Qz) and zoisite (Zo). We compare our experiments with a natural case - a sheared mafic pegmatite (P-T during deformation 0.7 - 0.9 GPa, 610 - 710 °C; Getsinger et al., 2013) from Northern Norway. Except for the difference in grain size of the experimental and natural samples, microstructures are strikingly alike. The experimental and natural P- and especially T-conditions are very similar. Consequently, extrapolation from experiments to nature must be made without a significant 'temperature-time' trade-off, which is normally taken advantage of when relating experimental to natural strain rates. We will discuss under which assumptions extrapolation to nature in our case is likely feasible. Syn-kinematic reactions during GBS and solution-mass transport are commonly interpreted to result in an ordered (anticlustered) phase mixture. However, phase mixing in our case is restricted: Mixing is extensive between Pl + Zo + Qz and

  15. SIMS Investigations on Growth and Sector Zoning in Natural Hydrothermal Quartz: Isotopic and Trace Element Analyses

    Science.gov (United States)

    May, E.; Vennemann, T. W.; Baumgartner, L. P.; Meisser, N.

    2014-12-01

    Quartz is the most abundant mineral in the Earth's crust and is found in virtually every geological context. Despite its ubiquity and the detailed studies on the conditions of quartz crystallization, some questions concerning its growth and sector zoning with regard to trace element incorporation and oxygen isotope fractionations and the implications thereof for interpretations on the conditions of formation remain (e.g., Jourdan et al., 2009). This study presents new in-situ measurements of trace element and oxygen isotope ratios on natural hydrothermal quartz from an extensional gold-bearing quartz vein in the western Swiss Alps. The temperature of formation of the veins is estimated by quartz-hematite oxygen isotope thermometry to be about 360°C. A detailed SEM-CL study of this sample shows cyclic lamellar growth, alternating with phases of dissolution that are directly followed by macro-mosaic growth of the quartz, before returning to a cyclic lamellar growth again. Trace element concentrations (measured for Na, K, Li, Al, and Ti) notably showed Al/Si variations of three orders of magnitude and coupled Al and Li variations, likely substituting for Si in different growth zones with lower values in macro-mosaic zones precipitating after the period of dissolution. The oxygen isotope composition of the crystal, in contrast, is homogeneous through all growth zones (δ18O values between 15.6‰ and 16.2‰) indicating that the fluid must have been buffered by the host-rock and/or the source of the fluid remained the same despite the period of quartz dissolution. Furthermore, the temperature during crystallization of the quartz crystal has likely also remained similar. The fact that no variations are measured in oxygen isotope compositions but some variations in trace element contents may suggest that changes in pressure were important during the formation of this quartz crystal. Give the pressure effects on the solubility of quartz (Fournier and Potter, 1982), both

  16. Grain centre mapping - 3DXRD measurements of average grain characteristics

    DEFF Research Database (Denmark)

    Oddershede, Jette; Schmidt, Søren; Lyckegaard, Allan

    2014-01-01

    Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage characteris......Three-Dimensional X-ray Diraction (3DXRD) Microscopy is a generic term covering a variety of dierent techniques for characterising the mi- crostructure within the bulk of polycrystalline materials. One strategy | namely grain centre mapping | enables fast measurements of the av- erage...... and the closely related boxscan method is given. Both validation experiments and applications for in situ studies of microstructural changes during plastic deformation and crack growth are given. Finally an outlook with special emphasis on coupling the measured results with modelling is given....

  17. Quartz Sand Resources In The Santa Maria Eterna Formation, Bahia, Brazil: A Geochemical And Morphological Study

    OpenAIRE

    Marques dos Santos; Murilo Ferreira; Fujiwara; Eric; Schenkel; Egont Alexandre; Enzweiler; Jacinta; Suzuki; Carlos Kenichi

    2016-01-01

    This study presents an evaluation of the quartz sand occurrences of the Santa Maria Eterna formation, in northeastern Brazil, as a potential source of raw material for silica glass manufacturing. Samples of quartz sand were analyzed by ICP-MS to determine a range of trace elements and establish its chemical purity. The technological potential of the sand was obtained by counting the quantity of bubbles formed during flame fusion over silica plate. Both chemistry and bubble formation indicate ...

  18. The optical absorption of gamma irradiated and heat-treated natural quartz

    Directory of Open Access Journals (Sweden)

    Eduardo Henrique Martins Nunes

    2005-09-01

    Full Text Available Quartz with aluminum as impurity absorbs energy from ionizing radiation and modifies its color. Colorless quartz becomes smoky or dark smoky (morion quartz when exposed to gamma rays. By heat-treatment, smoky quartz may become successively greenish, yellowish, or brownish as the irradiation dose increases. Natural, colorless quartz is routinely colored by irradiation with gamma rays and heat-treatment for jewelry production. The color formation in natural quartz through this procedure is explained based on EPR, UV-VIS, and IR studies of irradiated and irradiated and heat-treated samples. Smoky quartz shows absorption bands in the visible region and a strong EPR signal. After heat-treatment it shows absorption bands in the near UV region with extensions into the visible region and a weak EPR signal. The intensity of the absorption bands is proportional to the irradiation dose. These changes of color are explained by the model of Itoh, Stoneham, and Stoneham. [AlSi O4 /h+]0 centers are produced by irradiation, causing the EPR signal and the absorption bands in the visible region. [AlSi O4]- centers are created from [AlSi O4 /h+]0 centers by heat-treatment. They cannot cause an EPR signal and have absorption bands in the near UV region with extensions into the visible region. The highest concentration of [AlSi O4]- centers occurs when the charge compensators have medium mobility. Lithium should give the best condition for color formation. Sodium (low mobility and hydrogen (high mobility should make smoky quartz colorless after heat-treatment.

  19. Correct interpretation of diffraction properties of quartz crystals for X-ray optics applications

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xian-Rong; Gog, Thomas; Kim, Jungho; Kasman, Elina; Said, Ayman H.; Casa, Diego M.; Wieczorek, Michael; Hönnicke, Marcelo G.; Assoufid, Lahsen

    2018-02-01

    Quartz has hundreds of strong Bragg reflections that may offer a great number of choices for making fixed-angle X-ray analyzers and polarizers at virtually any hard X-ray energies with selectable resolution. However, quartz crystals, unlike silicon and germanium, are chiral and may thus appear in two different forms of handedness that are mirror images. Furthermore, because of the threefold rotational symmetry along thecaxis, the {h1h2h3L} and {h2h1h3L} Bragg reflections may have quite different Darwin bandwidth, reflectivity and angular acceptance, although they have the same Bragg angle. The design of X-ray optics from quartz crystals therefore requires unambiguous determination of the orientation, handedness and polarity of the crystals. The Laue method and single-axis diffraction technique can provide such information, but the variety of conventions used in the literature to describe quartz structures has caused widespread confusion. The current studies give detailed guidelines for design and fabrication of quartz X-ray optics, with special emphasis on the correct interpretation of Laue patterns in terms of the crystallography and diffraction properties of quartz. Meanwhile, the quartz crystals examined were confirmed by X-ray topography to have acceptably low densities of dislocations and other defects, which is the foundation for developing high-resolution quartz-based X-ray optics.

  20. [Influence of spectral interferences on the results of quartz determination by infrared spectrometry].

    Science.gov (United States)

    Maciejewska, Aleksandra

    2015-01-01

    Determination of quartz by Fourier transform infrared spectrometry (FTIR) is not specific: the obtained results are influenced by matrix components, some of which cause spectral interference. The aim of the study was to evaluate the effect of dust components responsible for spectral interference with quartz on the results of its determinations, and to develop methods to minimize the effects of interferences. Investigation of interferent effects were conducted using respirable dusts: quartz SRM 1878a, cristobalite SRM 1879a, synthetic amorphous silica (Zeosil) and feldspar, albite and kaolinite. For the study 17 mixtures with quartz and interferents at concentrations from 10 to 90% were prepared. Determinations of quartz were carried out by the KBr disc method. In mixtures of quartz with interferents, the results based on bands 798-779 cm-1 were overestimated by 10-55%, while those based on band 695 cm-1 were closer to the true content of quartz. It was found that the best methods able to decrease the impact of spectral interference are: scaled subtraction of IR spectra of feldspar or kaolinite analysed in nonashed samples, correction curve for kaolinite also investigated in nonashed samples with quartz-content calculation based on band 695 cm-1 in mixtures with cristobalite, amorphous silica or kaolinite in ashed samples. The study indicates the need to identify spectral interferences in dust when determining crystalline silica by FT-IR and to take actions to minimize their impact on the obtained results. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  1. Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

    OpenAIRE

    Andreas Pohlkötter; Michael Köhring; Ulrike Willer; Wolfgang Schade

    2010-01-01

    Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system a detection limit of 13 ppm is reached with a compact and long term stable setup. Further improvement of the detection limit is possible by adding suitable gases to the sa...

  2. Influence of spectral interferences on the results of quartz determination by infrared spectrometry

    Directory of Open Access Journals (Sweden)

    Aleksandra Maciejewska

    2015-07-01

    Full Text Available Background: Determination of quartz by Fourier transform infrared spectrometry (FTIR is not specific: the obtained results are influenced by matrix components, some of which cause spectral interference. The aim of the study was to evaluate the effect of dust components responsible for spectral interference with quartz on the results of its determinations, and to develop methods to minimize the effects of interferences. Material and Methods: Investigation of interferent effects were conducted using respirable dusts: quartz SRM 1878a, cristobalite SRM 1879a, synthetic amorphous silica (Zeosil and feldspar, albite and kaolinite. For the study 17 mixtures with quartz and interferents at concentrations from 10 to 90% were prepared. Determinations of quartz were carried out by the KBr disc method. Results: In mixtures of quartz with interferents, the results based on bands 798–779 cm–1 were overestimated by 10–55%, while those based on band 695 cm–1 were closer to the true content of quartz. It was found that the best methods able to decrease the impact of spectral interference are: scaled subtraction of IR spectra of feldspar or kaolinite analysed in nonashed samples, correction curve for kaolinite also investigated in nonashed samples with quartz-content calculation based on band 695 cm–1 in mixtures with cristobalite, amorphous silica or kaolinite in ashed samples. Conclusions: The study indicates the need to identify spectral interferences in dust when determining crystalline silica by FT-IR and to take actions to minimize their impact on the obtained results. Med Pr 2015;66(4:497–509

  3. Emission of dislocations from grain boundaries by grain boundary dissociation

    Science.gov (United States)

    Hoagland, Richard G.; Valone, Steven M.

    2015-01-01

    In this article, we examine the conditions that favour the emission of Shockley partial dislocations (SPDs) that standoff from a grain boundary (GB) plane by a few lattice parameters as part of the atomic structure of some GBs. To do so, we consider GBs to be formed by the operation of arrays of intrinsic grain boundary dislocations (GBDs) that create the tilt and twist misorientation, and the lattice mismatch between the two crystal grains adjoining the GB. The conditions to be considered that favour SPDs are the following: (1) Frank's rule, (2) the proper sequential arrangement of partial dislocations to bound an intrinsic stacking fault and (3) the equilibrium stand-off distance (ESD). We apply an isotropic elasticity analysis to compute the ESD, in the absence of an applied stress, for SPDs emerging from asymmetric tilt GBs in two FCC metals, Cu and Al. The ESD is shown to be dependent on the glide plane orientation relative to the GB plane and on the position of the glide planes, relative to the position of the GBDs. An applied stress increases the ESD up to a critical stress that removes the SPDs without limit from the GB. We examine the effect of the stacking fault energy on the ESD and critical stress. The critical stress is effectively linearly dependent on the stacking fault energy. Finally, we present results of atomistic simulations of asymmetric tilt Σ11[1 0 1]{4 1 4}||{2 5 2} GBs in Cu bicrystal models subject to shock loading that behave in a manner similar to the elasticity predictions. The atomistic simulations reveal additional behaviour associated with elastic incompatibility between the two grains in the bicrystal models.

  4. Effect of particle size in the TL response of natural quartz sensitized by high dose of gamma radiation and heat-treatments

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho Junior, Alvaro Barbosa de [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Graduate Program of Mechanical Engineering; Guzzo, Pedro Luiz, E-mail: pguzzo@ufpe.b [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Dept. of Mining Engineering; Sullasi, Henry Lavalle [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Dept. of Archeology; Khoury, Helen Jamil [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Dept. of Nuclear Energy

    2010-07-01

    This work investigates the effect of particle size in the thermoluminescence (TL) response of a quartz crystal that was initially crushed and classified into ten size fractions between 38 {mu}m and 5 mm. Aliquots of each size fraction were sensitized with a dose of 25 kGy of {gamma} rays and heat-treatments at 400 deg C. TL glow curves of sensitized and non-sensitized samples were recorded as a function of different test-doses of {gamma} rays. For the non-sensitized samples, the TL peak near 325 deg C increases with the decrease in particle size. In the case of sensitized samples, a strong TL peak near 300 deg C increases with the increase in particle size up to mean grain size equal to 304 {mu}m. Above 304 ({mu}m, an abrupt reduction in the TL intensity is noticed for the sensitized peak. These effects are discussed in relation to the specific surface area of quartz particles and the intensity of the electron paramagnetic resonance signal of the E{sub 1}{sup '} center induced by the sensitization process. (author)

  5. Effect of particle size in the TL response of natural quartz sensitized by high dose of gamma radiation and heat-treatments

    Directory of Open Access Journals (Sweden)

    Álvaro Barbosa de Carvalho Jr

    2010-06-01

    Full Text Available This work investigates the effect of particle size in the thermoluminescence (TL response of a quartz crystal that was initially crushed and classified into ten size fractions between 38 μm and 5 mm. Aliquots of each size fraction were sensitized with a dose of 25 kGy of γ rays and heat-treatments at 400 °C. TL glow curves of sensitized and non-sensitized samples were recorded as a function of different test-doses of γ rays. For the non-sensitized samples, the TL peak near 325 °C increases with the decrease in particle size. In the case of sensitized samples, a strong TL peak near 300 °C increases with the increase in particle size up to mean grain size equal to 304 μm. Above 304 μm, an abrupt reduction in the TL intensity is noticed for the sensitized peak. These effects are discussed in relation to the specific surface area of quartz particles and the intensity of the electron paramagnetic resonance signal of the E'1 center induced by the sensitization process.

  6. Relationship of Technological Properties with Dynamic Recrystallization of Quartz on the Example of Objects of the Karelian-Kola Region

    Science.gov (United States)

    Skamnitskaya, Lubov; Rakov, Leonid; Bubnova, Tatyana; Shchiptsov, Vladimir

    2017-12-01

    Despite the significant reserves of quartz raw materials, there is a deficit of high purity quartz. It is due to the strict technical requirements imposed by standards for this type of raw materials and technological properties of quartz, which are determined by the features of the crystal structure. The crystalline structure is of particular importance for the technological properties of quartz, since such important characteristics as the limit of raw material enrichment, dissolution rate in acid, melting point of quartz, etc., are determined. The formation of the crystal structure of quartz under natural conditions is associated with the successive dynamic recrystallization of the mineral. The degree of dynamic recrystallization of quartz reflects the distribution of dispersed impurities. If it is weakly manifested, the dispersed impurities are not displaced from one zone to another, and all quartz microblocks contain approximately the same concentration. In this case, more or less uniform dissolution of various regions of quartz is observed, and the pattern of distribution of submicroscopic inhomogeneities is monotonic. If intensive dynamic recrystallization of quartz takes place, then it causes a significant redistribution of the scattered impurities. Then the treatment in HF leads to the appearance of a contrast pattern of the distribution of submicroscopic inhomogeneities. The details of the crystal structure of quartz in this work were investigated by the electron paramagnetic resonance (EPR) method using the ER-420 “Bruker” spectrometer. In the selected samples of quartz, the concentrations of isomorphic impurities Al and Ti were measured, and the degree of crystallinity D of the mineral was estimated from the EPR spectra of each of them. Thus, the technological properties of quartz are determined by various geological processes. The results of the studies show that when evaluating the prospects of quartz raw materials, it is necessary to take into

  7. The response of quartz crystals coated with thin fatty acid film to organic gases

    CERN Document Server

    Jin, C N; Kim, K H; Kwon, Y S

    1999-01-01

    We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C sub 1 sub 4), palmitic acid (C sub 1 sub 6), stearic acid (C sub 1 sub 8), and arachidic acid (C sub 2 sub 0) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found that quar...

  8. Importance of surface characteristics of QUARTZ DQ 12 for acute inflammation

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, C.; Becher, A.; Scins, R.P.F.; Hoehr, D.; Unfried, K.; Knaapen, A.M.; Borm, P.J.A. [Institut fuer medizinische Forschung (IUF), Duesseldorf (Germany)

    2004-07-01

    Although quartz is known to induce inflammation in rat lungs, mechanisms are not yet fully understood. The importance of particle surface characteristics was investigated in vivo after intratracheal instillation of different preparations of quartz in rat lungs. Three days after instillation of 2 mg DQ12 quartz, or DQ12 coated with polyvinylpyridine-N-oxide (PVNO) or Aluminium lactate (AL), lungs of female Wistar rats were lavaged in situ to determine markers of inflammation. Control rats received saline or the coating substances alone. DQ12 induced a marked inflammatory response, as indicated by a significant increase in the number of neutrophils and macrophages, as well as in the levels of b-glucuronidase and myeloperoxidase. None of these inflammatory markers was increased for both coated quartz preparations, with the exception of neutrophil influx which was also increased after treatment with AL quartz. Our results indicate that surface characteristics are important in the onset of quartz-induced lung inflammation which could imply a different development of persistent inflammation. This will be investigated in later follow-up time points of the same animal study. (orig.)

  9. Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz.

    Science.gov (United States)

    Budd, David A; Troll, Valentin R; Deegan, Frances M; Jolis, Ester M; Smith, Victoria C; Whitehouse, Martin J; Harris, Chris; Freda, Carmela; Hilton, David R; Halldórsson, Sæmundur A; Bindeman, Ilya N

    2017-01-25

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ(18)O values. Overall, Toba quartz crystals exhibit comparatively high δ(18)O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ(18)O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core-rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ(18)O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ(18)O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  10. Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz

    Science.gov (United States)

    Budd, David A.; Troll, Valentin R.; Deegan, Frances M.; Jolis, Ester M.; Smith, Victoria C.; Whitehouse, Martin J.; Harris, Chris; Freda, Carmela; Hilton, David R.; Halldórsson, Sæmundur A.; Bindeman, Ilya N.

    2017-01-01

    Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core-rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

  11. BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

    Directory of Open Access Journals (Sweden)

    Raharjo Raharjo

    2010-06-01

    Full Text Available An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed method in the column filled by the bentonite mixture with a bentonite-to-quartz sand weight percent ratio of 0/100, 25/75, 50/50, 75/25, and 100/0 on the water saturated condition flown by uranyl nitrate solution at concentration (Co of 500 ppm. The concentration of uranium in the effluents in interval 15 minutes represented as Ct was analyzed by spectrophotometer, then using Co and Ct, retardation factor (R and dispersivity ( were determined. The experiment data showed that the bentonite of -60+80 mesh and the quartz sand of -20+40 mesh on bentonite-to-quartz sand with weight percent ratio of 50/50 gave the highest retardation factor and dispersivity of 18.37 and 0.0363 cm, respectively.   Keywords: bentonite, quartz sand, backfill materials, radioactive waste

  12. Molecular modeling of interactions between heavy crude oil and the soil organic matter coated quartz surface.

    Science.gov (United States)

    Wu, Guozhong; Zhu, Xinzhe; Ji, Haoqing; Chen, Daoyi

    2015-01-01

    Molecular dynamic (MD) simulation was applied to evaluate the mobility, diffusivity and partitioning of SARA (saturates, aromatics, resins, asphaltenes) fractions of heavy crude oil on soil organic matter (SOM) coated quartz surface. Four types of SOM were investigated including Leonardite humic acid, Temple-Northeastern-Birmingham humic acid, Chelsea soil humic acid and Suwannee river fulvic acid. The SOM aggregation at oil-quartz interface decreased the adsorption of SARA on the quartz surface by 13-83%. Although the SOM tended to promote asphaltenes aggregation, the overall mobility of SARA was significantly greater on SOM-quartz complex than on pure quartz. Particularly, the diffusion coefficient of asphaltenes and resins increased by up to one-order of magnitude after SOM addition. The SOM increased the overall oil adsorption capacity but also mobilized SARA by driving them from the viscous oil phase and rigid quartz to the elastic SOM. This highlighted the potential of SOM addition for increasing the bioavailability of heavy crude oil without necessarily increasing the environmental risks. The MD simulation was demonstrated to be helpful for interpreting the role of SOM and the host oil phase for the adsorption and partitioning of SARA molecules, which is the key for developing more realistic remediation appraisal for heavy crude oil in soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Some experiments on the high-low transition of quartz; Recherches experimentales sur une transformation du quartz

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-12-15

    First section. - We expose on the one hand a theory of specific heat, thermal expansion and variations of elastic constants as functions of temperature, which is applicable only in the absence of transformation phenomena affecting symmetry or periodicity of the crystal lattice. On the other hand, we discuss some theories relative to the phenomena which accompany phase transformations. Second section. - We have gathered together numerical results concerning elastic, piezoelectric and optical properties of quartz. Some have been collected from the literature, other have been obtained in our laboratories with the help of experimental methods which we describe. As a result, we are able to present a complete picture of the evolution of these constants in a large temperature range containing the critical temperature of 574 deg. C at which these constants exhibit discontinuities. New phenomena have been observed, in the course of these studies. Third section. - We show that the evolution of the two piezoelectric and elastic constants which cancel out in the high temperature form is described by the same function. With the inclusion of one other function, it is possible to explain quantitatively the behaviour in the transformation range of all the other constants under study. With the help of crystallographic considerations and of hypotheses concerning the nature of the transformation entropy, we finally try to account for the experimental values of these two functions. (author) [French] Dans une premiere partie, nous exposons d'une part une theorie de la chaleur specifique, de la dilatation thermique et des variations des constantes elastiques des solides avec la temperature qui n'est valable qu'en l'absence de phenomenes de transformation affectant la symetrie ou la periodicite de l'edifice cristallin, et nous rappelons d'autre part quelques theories relatives aux phenomenes qui accompagnent les changements de phase. Dans une seconde partie

  14. Pedogenic replacement of aluminosilicate grains by CaCO3 in Ustollic Haplargids, south-central Montana, U.S.A.

    Science.gov (United States)

    Reheis, M.C.

    1988-01-01

    A chronosequence of calcic soils formed on granitic glaciofluvial terrace deposits of Rock Creek and the Clarks Fork in south-central Montana shows progressive replacement of aluminosilicate parent-material grains by calcium-magnesium carbonate. The terraces range from late Pliocene to Holocene in age as dated by tephrochronology, correlation, and stream incision rates. Replacement is first seen in soils that are as old as 120,000 yr; the amount and degree of replacement increase in soils older than 120,000 yr along with the development of calcic horizons. Under the petrographic microscope, carbonate replacement of quartz, feldspars, and the groundmass of andesite grains in Rock Creek soils is shown by embayed grains, networks of carbonate along cracks and between parts of polycrystalline grains and optically aligned grain fragments within carbonate masses. Microprobe data suggest that silica is released by replacement because it is absent from carbonate-filled spaces and is depleted in corrosion pits. Little microscopic evidence exists to support displacement of framework grains by carbonate because fragments of a single grain are rarely rotated out of optical alignment. In the calcic soils of Rock Creek, K-fabric (grains floating in a carbonate matrix) may form by both replacement and displacement. ?? 1988.

  15. Molecule Formation on Interstellar Grains

    Science.gov (United States)

    Vidali, G.

    2011-05-01

    The first experiments that were expressively designed to be applicable to hydrogen formation reactions in the ISM measured the efficiency of formation of molecular hydrogen on a polycrystalline olivine (Pirronello et al. (1997a)). It soon turned out that more was needed, and research began on the mechanism of reaction, on the in uence of the surface morphology, and on the excitation of the just- ormed molecule. In this review, I summarize what we learned from these and other experiments, and where more work is needed: in the elementary steps of reaction, in the bridging of the laboratory-ISM gap (large ux/large surface - small ux/small grain) using simulations, and in using realistic samples of dust grains. Understanding what experiments can and cannot deliver will help in designing and targeting observations, and vice-versa.

  16. Crop rotations for grain production

    OpenAIRE

    Olesen, Jørgen E.; Rasmussen, Ilse Ankær; Askegaard, Margrethe

    2000-01-01

    There is an increasing demand for organically grown cereal grains in Denmark, which is expected to cause a change in the typical organic farm structure away from dairy farming and towards arable farming. Such a change may reduce the stability of the farming systems, because of decreasing soil fertility and problems with weed control. There have only been a limited number of studies under temperate conditions in Europe and North America, where different crop rotations have been compared under ...

  17. Structure and properties of grain boundaries

    Science.gov (United States)

    Balluffi, R. W.; Bristowe, P. D.

    1984-03-01

    Results were obtained in the following areas: determination of relative grain boundary energies by the rotating crystallite method; simple structural unit model for core dependent properties of tilt boundaries; twist boundary energies for metals with long ranged pairwise interatomic potentials; structural unit/grain boundary dislocation model for grain boundary structure; detection of expansion of boundaries using diffraction; effect of secondary relaxations on diffraction from high-(SIGMA) 001 twist boundaries; and mechanism of grain boundary migration.

  18. Effect of Transplanting Times on Rate and Duration of Grain Filling, Final Grain Weight and Grain Yield of Rice Cultivars

    Directory of Open Access Journals (Sweden)

    A. Vahdati-Rad

    2016-05-01

    Full Text Available In order to investigate the effects of temperature and radiation on rate and duration of grain filling and final grain weight in rice cultivars, a split plot experiment based on randomized complete block design with three replications was conducted at different transplanting times at the research field of University of Guilan, Rasht, Iran in 2013. Factors were: transplanting dates in main plots (5 May, 20 May and 5 June and rice cultivars (Hashemi, Ali Kazemi, Sangejo, Khazar, Dorfak and Gouhar in sub plots. The greatest grain weight (31.9 mg was obtained in Gouhar at 20 May and the smallest grain weight (20.4 mg was observed in Sangejo at 5 June transplanting dates. The longest effective filling period (32.9 days was achieved in Gouhar at 5 May transplanting date and the shortest grain filling duration (13.9 days was obtained in Hashemi. The greatest grain filling rate (1.62 mg day-1 was obtained in the Hashemi and the smallest rate (0.92 mg day-1 was observed in Gouhar. Significant correlations were observed between cumulative temperature and radiation with final grain weight (R = 0.689. There were significant and positive correlations between the cumulative temperature and irradiance with grain filling duration, in contrary to negative correlations with grain filling rate and grain filling period. The results of this experiment showed that the grain filling duration plays a greater role, than grain filling rate, in determination of the grain weight. It could be concluded that an early transplanting (5 May brings about favorable temperature and radiation conditions for an appropriate grain filling period and a greater final grain weight.

  19. Small grains and IRAS colors

    Science.gov (United States)

    Boulanger, F.; Beichman, C.; Helou, G.; Desert, F. X.; Perault, M.

    1988-01-01

    The paper studies how infrared colors of dust emission from the interstellar medium vary with the energy density of the radiation field on the basis of IRAS observation of the California Nebula. The data suggest that color variations result from a combinatin of equilibrium emission from large grains, and nonequilibrium emission from small grains, with destruction of the small grains emitting at 12 microns at high energy density; it is estimated that 80 percent of these small particles are destroyed for an energy density in ultraviolet photons larger than 50 times that of the average interstellar radiation field in the solar neighborhood. In a color-color diagram, I(v)(60 microns)/I(v)(100 microns) versus I(v)(12 microns)/I(v)(25 microns), the California Nebula measurements at various distances to the ionizing star Zeta Per follow a sequence similar to that of galaxies. This result shows that the position of a galaxy along this sequence is a measure of the intensity of the radiation field in the regions responsible for the infrared emission.

  20. Grain Boundary Energies in Copper.

    Science.gov (United States)

    Omar, Ramli

    Available from UMI in association with The British Library. Requires signed TDF. The dependence of grain boundary energy on boundary orientation was studied in copper annealed at 1000 ^circC. Grain boundary orientations and the disorientations across the boundaries were measured. A rotation matrix notation is used to interpret selected area electron channelling patterns observed in a scanning electron microscope. The Herring and Shewmon torque terms were investigated using wire specimens having a "bamboo" structure. The Herring torque terms were determined using the Hess relation. The (110) section of the Sigma 11 gamma-plot (i.e. the variation of grain boundary energy with boundary orientation) was evaluated. In this plot, minima in energies were found at the (311) and (332) mirror planes. Sigma 3 and Sigma9 boundaries were investigated in sheet specimens. The (110) and (111) sections of the Sigma3 gamma -plot were evaluated. In addition to the sharp cusps occurring at the Sigma3 {111} planes, the further shallower cusps occur at the incoherent Sigma 3 boundaries with the interfacial planes approximately parallel to {322} in one crystal and {11.44} in the other crystal. Flat and curved Sigma9 boundaries were investigated. The break up of Sigma9 boundaries into two Sigma3 boundaries and the relation between the Sigma3 and Sigma 9 gamma-plots was also examined. The (110) section of the Sigma9 gamma-plot was constructed.

  1. Competitive Adsorption of Plasma Proteins Using a Quartz Crystal Microbalance.

    Science.gov (United States)

    Felgueiras, Helena P; Murthy, N Sanjeeva; Sommerfeld, Sven D; Brás, M Manuela; Migonney, Véronique; Kohn, Joachim

    2016-06-01

    Proteins that get adsorbed onto the surfaces of biomaterials immediately upon their implantation mediate the interactions between the material and the environment. This process, in which proteins in a complex mixture compete for adsorption sites on the surface, is determined by the physicochemical interactions at the interface. Competitive adsorption of bovine serum albumin (BSA), fibronectin (Fn), and collagen type I (Col I), sequentially and from mixtures, was investigated so as to understand the performances of different surfaces used in biomedical applications. A quartz crystal microbalance with dissipation was used to monitor the adsorption of these proteins onto two materials used in functional bone replacement, a titanium alloy (Ti6Al4V) and Ti6Al4V physisorbed with poly(sodium styrenesulfonate) [poly(NaSS)], and three controls, gold, poly(desaminotyrosyltyrosine ethyl ester carbonate) [poly(DTEc)], and polystyrene (PS). In experiments with individual proteins, the adsorption was the highest with Fn and Col I and the least with BSA. Also, protein adsorption was the highest on poly(NaSS) and Ti6Al4V and the least on poly(DTEc). In sequential adsorption experiments, protein exchange was observed in BSA + Fn, Fn + Col I, and BSA + Col I sequences but not in Fn + BSA and Col I + BSA because of the lower affinity of BSA to surfaces relative to Fn and Col I. Protein adsorption was the highest with Col I + Fn on hydrophobic surfaces. In experiments with protein mixtures, with BSA & Fn, Fn appears to be preferentially adsorbed; with Fn & Col I, both proteins were adsorbed, probably as multilayers; and with Col I & BSA, the total amount of protein was the highest, greater than that in sequential and individual adsorption of the two proteins, probably because of the formation of BSA and Col I complexes. Protein conformational changes induced by the adsorbing surfaces, protein-protein interactions, and affinities of proteins appear to be the important factors that

  2. Effect of high gamma-doses in the sensitization of natural quartz for thermoluminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Khoury, H.J.; Guzzo, P.L.; Brito, S.B. [Universidade Federal de Pernambuco, 50740-540 Recife PE (Brazil)

    2006-07-01

    Sensitization is an important effect in radiation dosimetry using thermoluminescent (TL materials where the enhancement of sensitivity is a desirable feature. Until known, the investigation of sensitization in quartz has been restricted to its first glow peak appearing around 110 C. In addition, the sensitization process has been essentially produced by heat-treatments in powdered quartz. The aim of this study is to investigate the sensitization process in the second glow peak of crystalline quartz using high doses of gamma irradiation. For this, five lots of samples were prepared from quartz single crystals issued from different geologies in Brazil. Chips of 5 x 5 x 1 mm{sup 3} (60 mg) were cut and lapped parallel to the (0001) plane. The specimens were initially irradiated with doses of gamma radiation of {sup 137} Cs in the range of 10 mGy to 10 Gy in order to determine its TL response curve. After that, the specimens were submitted to successive high doses of gamma-irradiation with {sup 60} Co from 25 kGy to 350 kGy. After each irradiation, the TL response curves to gamma radiation of {sup 137} Cs were determined for each quartz lot irradiated in the range of 2 to 20 mGy. The TL measurements were carried out with a 2800M Victoreen reader using the step mode. The step parameters were set in 10 s from 30 to 160 C (first region) and in 20 s from 160 to 320 C (second region). The absolute TL signal used to obtain the calibration curves represented the sum of electric charges under the glow peak appearing in the second region. The results showed that the TL response of the quartz studied increased with the dose sensitization, so that the TL response for 10mGy of {sup 137} Cs radiation varied from 0.05 nC/mg for the quartz without sensitization to 10 nC/mg after a sensitization with 50 kGy of gamma radiation of {sup 60} Co. The effect of sensitization with high doses of gamma irradiation was clearly observed for three quartz lots and it was observed that the high

  3. Red grain mycetoma foot in Western Rajasthan

    Directory of Open Access Journals (Sweden)

    Mathur D

    1994-01-01

    Full Text Available Usually the colour of the grains seen in cases of mycetoma are either black or yellow. Recently there were reports that unusual red grains had been noticed in cases of mycetoma. A case of red grain mycetoma is reported.

  4. Structure and chemistry of the sorghum grain

    Science.gov (United States)

    Sorghum is grown around the world and often under harsh and variable environmental conditions. Combined with the high degree of genetic diversity present in sorghum, this can result in substantial variability in grain composition and grain quality. While similar to other cereal grains such as maize ...

  5. Bioactive compounds in whole grain wheat

    NARCIS (Netherlands)

    Mateo Anson, N.

    2010-01-01

    Bread can be healthier! Consuming whole-grain foods can prevent cardiovascular diseases, type-2 diabetes and metabolic syndrome. This is due to bioactive compounds in whole grain, such as antioxidants and anti-inflammatory compounds. We found that the different fractions of a wheat grain vary much

  6. Determination of grain boundary geometry using TEM

    NARCIS (Netherlands)

    Jang, H.; Farkas, D.; Hosson, J.T.M. De

    An experimental method to obtain the grain boundary geometry using the transmission electron microscope is presented. The method allows Σ determination including grain boundary plane orientation. In order to determine the specialness of the grain boundary, three different criteria for maximum

  7. Quartz phenocrysts preserve volcanic stresses at Long Valley and Yellowstone calderas

    Science.gov (United States)

    Befus, K. S.; Leonhardi, T. C.; Manga, M.; Tamura, N.; Stan, C. V.

    2016-12-01

    Magmatic processes and eruptions are the consequence of stresses active in volcanic environments. Few techniques are presently available to quantify those stresses because they operate in subsurface and/or hazardous environments, and thus new techniques are needed to advance our understanding of key processes. Here, we provide a dataset of volcanic stresses that were imparted to quartz crystals that traveled through, and were hosted within, pyroclastic and effusive eruptions from Long Valley and Yellowstone calderas. We measured crystal lattice deformation with submicron spatial resolution using the synchrotron X-ray microdiffraction beamline (12.3.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Quartz from all units produces diffraction patterns with residual strains locked in the crystal lattice. We used Hooke's Law and the stiffness constants of quartz to calculate the stresses that caused the preserved residual strains. At Long Valley caldera, quartz preserves stresses of 187±80 MPa within pumice clasts in the F1 fall unit of the Bishop Tuff, and preserves stresses of 120±45 MPa from the Bishop Tuff welded ignimbrite. At Yellowstone caldera quartz preserves stresses of 115±30 and 140±60 MPa within pumices from the basal fall units of the Mesa Falls Tuff and the Tuff of Bluff Point, respectively. Quartz from near-vent and flow-front samples from Summit Lake lava flow preserves stresses up to 130 MPa, and show no variation with distance travelled. We believe that subsurface processes cause the measured residual stresses, but it remains unclear if they are relicts of fragmentation or from the magma chamber. The residual stresses from both Long Valley and Yellowstone samples roughly correlate to lithostatic pressures estimated for the respective pre-eruption magma storage depths. It is possible that residual stress in quartz provides a new geobarometer for crystallization pressure. Moving forward, we will continue to perform analyses and

  8. Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate.

    Science.gov (United States)

    Schauer, Andrew J; Kunasek, Shelley A; Sofen, Eric D; Erbland, Joseph; Savarino, Joel; Johnson, Ben W; Amos, Helen M; Shaheen, Robina; Abaunza, Mariana; Jackson, Terri L; Thiemens, Mark H; Alexander, Becky

    2012-09-30

    Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data. Copyright © 2012 John Wiley & Sons, Ltd.

  9. Consideration of kaolinite interference correction for quartz measurements in coal mine dust.

    Science.gov (United States)

    Lee, Taekhee; Chisholm, William P; Kashon, Michael; Key-Schwartz, Rosa J; Harper, Martin

    2013-01-01

    Kaolinite interferes with the infrared analysis of quartz. Improper correction can cause over- or underestimation of silica concentration. The standard sampling method for quartz in coal mine dust is size selective, and, since infrared spectrometry is sensitive to particle size, it is intuitively better to use the same size fractions for quantification of quartz and kaolinite. Standard infrared spectrometric methods for quartz measurement in coal mine dust correct interference from the kaolinite, but they do not specify a particle size for the material used for correction. This study compares calibration curves using as-received and respirable size fractions of nine different examples of kaolinite in the different correction methods from the National Institute for Occupational Safety and Health Manual of Analytical Methods (NMAM) 7603 and the Mine Safety and Health Administration (MSHA) P-7. Four kaolinites showed significant differences between calibration curves with as-received and respirable size fractions for NMAM 7603 and seven for MSHA P-7. The quartz mass measured in 48 samples spiked with respirable fraction silica and kaolinite ranged between 0.28 and 23% (NMAM 7603) and 0.18 and 26% (MSHA P-7) of the expected applied mass when the kaolinite interference was corrected with respirable size fraction kaolinite. This is termed "deviation," not bias, because the applied mass is also subject to unknown variance. Generally, the deviations in the spiked samples are larger when corrected with the as-received size fraction of kaolinite than with the respirable size fraction. Results indicate that if a kaolinite correction with reference material of respirable size fraction is applied in current standard methods for quartz measurement in coal mine dust, the quartz result would be somewhat closer to the true exposure, although the actual mass difference would be small. Most kinds of kaolinite can be used for laboratory calibration, but preferably, the size fraction

  10. Grain-size sorting and slope failure in experimental subaqueous grain flows

    NARCIS (Netherlands)

    Kleinhans, M.G.; Asch, Th.W.J. van

    2005-01-01

    Grain-size sorting in subaqueous grain flows of a continuous range of grain sizes is studied experimentally with three mixtures. The observed pattern is a combination of stratification and gradual segregation. The stratification is caused by kinematic sieving in the grain flow. The segregation is

  11. Ferroelectric domain continuity over grain boundaries

    DEFF Research Database (Denmark)

    Mantri, Sukriti; Oddershede, Jette; Damjanovic, Dragan

    2017-01-01

    Formation and mobility of domain walls in ferroelectric materials is responsible for many of their electrical and mechanical properties. Domain wall continuity across grain boundaries has been observed since the 1950's and is speculated to affect the grain boundary-domain interactions, thereby...... orientation. We have also incorporated the effect of grain boundary ferroelectric polarization charge created when any two domains meet at the grain boundary plane. The probability of domain wall continuity for three specific grain misorientations is studied. Use of this knowledge to optimize processing...

  12. Grain storage at farm and warehouses level

    Directory of Open Access Journals (Sweden)

    Neacşu, A. N.

    2010-12-01

    Full Text Available Grain storage is very important because the quality of flour obtained from grain will be found in the finished products’ quality. Grains must be stored in well established conditions regarding temperature, humidity, airflow, trying to avoid the risk of being attacked by rodents and insects. If these conditions are not complied with, some qualitative deficits of the grains - such as mould at pH, infestation, fermentation etc. - may appear. The storage methods are those responsible for maintaining a good quality of the grains.

  13. Physical and chemical effects of grain aggregates on the Palos Verdes margin, southern California

    Science.gov (United States)

    Drake, D.E.; Eganhouse, R.; McArthur, W.

    2002-01-01

    Large discharges of wastewater and particulate matter from the outfalls of the Los Angeles County Sanitation Districts onto the Palos Verdes shelf since 1937 have produced an effluent-affected sediment deposit characterized by low bulk density, elevated organic matter content, and a high percentage of fine silt and clay particles relative to underlying native sands and sandy silts. Comparison of the results of grain-size analyses using a gentle wet-sieving technique that preserves certain grain aggregates to the results of standard size analyses of disaggregated particles shows that high percentages (up to 50%) of the silt and clay fractions of the effluent-affected mud are incorporated in aggregates having intermediate diameters in the fine-to-medium sand size range (63-500 ??m), Scanning electron microscope images of the aggregates show that they are predominantly oval fecal pellets or irregularly shaped fragments of pellets. Deposit-feeding polychaete worms such as Capitella sp. and Mediomastus sp., abundant in the mud-rich effluent-affected sediment on Palos Verdes shelf, are probably responsible for most of the grain aggregates through fecal pellet production. Particle settling rates and densities, and the concentrations of organic carbon and p,p???-DDE, a metabolite of the hydrophobic pesticide DDT, were determined for seven grain-size fractions in the effluent-affected sediment. Fecal pellet grain densities ranged from about 1.2 to 1.5 g/cc, and their average settling rates were reduced to the equivalent of about one phi size relative to spherical quartz grains of the same diameter. However, repackaging of fine silt and clay grains into the sand-sized fecal pellets causes an effective settling rate increase of up to 3 orders of magnitude for the smallest particles incorporated in the pellets. Moreover, organic carbon and p,p???-DDE exhibit a bimodal distribution with relatively high concentrations in the finest size fraction (0-20 ??m), as expected, and a

  14. The effect of mineralogy and grain breakage on shear-induced noise and auto-acoustic compaction

    Science.gov (United States)

    Taylor, S.; Brodsky, E. E.

    2014-12-01

    The behavior of granular flows is strongly dependent on shear rate. At relatively slow shear velocities, a granular flow will support stresses elastically through force chains in the quasi-static regime. At relatively high shear velocities, it will support stresses by transferring momentum in higher velocity grain collisions in the grain-inertial regime, which results in dilation of the flow. Experiments conducted using a commercial torsional rheometer (TA AR-2000ex) found that at intermediate shear velocities, force chain collapse in angular sand samples produces sound waves capable of vibrating the shear zone enough to cause compaction. Sound produced by spherical glass beads during shearing was of lower amplitude and no compaction effect was observed. In order to characterize both the source of acoustic energy produced during shearing of angular grains and its associated compaction effect, we used the same experimental set up to observe how volumetric and acoustic response to shear stress changes with mineralogy, specifically varying grain hardness and shear modulus. A comparison of angular quartz beach sand (Mohs hardness of 7 and shear modulus of 31.14 GPa) with angular aluminum oxide grit of the same size (Mohs hardness of 9 and shear modulus of 124 GPa) shows markedly different behavior, with the aluminum oxide mixture producing lower noise amplitudes during shearing and showing no compaction at intermediate shear rates. Combined with grain size and shape analysis, the implication is that shear-induced noise is the result of grain fracture rather than shear interactions and is dependent on the relative strength of individual grains. Combined with recent and ongoing work characterizing the effect of mean grain size and polydispersity on shear-induced volumetric and acoustic response, we are moving towards a more complete incorporation of field-observable variables into predictions of natural granular mixtures.

  15. Barnett relaxation in non-symmetric grains

    Science.gov (United States)

    Kolasi, Erald; Weingartner, Joseph C.

    2017-10-01

    Barnett relaxation, first described by Purcell in 1979, appears to play a major role in the alignment of grains with the interstellar magnetic field. In 1999, Lazarian and Draine proposed that Barnett relaxation and its relative, nuclear relaxation, can induce grains to flip. If this thermal flipping is rapid then the dynamical effect of torques that are fixed relative to the grain body can be greatly reduced. To date, detailed studies of Barnett relaxation have been confined to grains exhibiting dynamic symmetry. In 2009, Weingartner argued that internal relaxation cannot induce flips in any grains, whether they exhibit dynamic symmetry or not. In this work, we develop approximate expressions for the dissipation rate and diffusion coefficient for Barnett relaxation. We revisit the issue of internally induced thermal flipping, finding that it cannot occur for grains with dynamic symmetry, but does occur for grains lacking dynamic symmetry.

  16. Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body

    Science.gov (United States)

    Gualda, Guilherme A. R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Alfred T.; Sutton, Stephen R.; Rivers, Mark L.

    2012-01-01

    Supereruptions violently transfer huge amounts (100 s–1000 s km3) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ∼760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies. PMID:22666359

  17. Adsorption and Removal of Organic Dye at Quartz Sand-Water Interface

    Directory of Open Access Journals (Sweden)

    Jada A.

    2013-11-01

    Full Text Available We studied the transport, sorption and desorption of organic cation (Methylene Blue, MB through a porous medium consisting of quartz sand particles negatively charged. We examined various parameters such as the ionic strength of the aqueous solution, the flow velocity, the pH of the aqueous phase, the temperature of the medium and the nature of the divalent metal cations present in solution, which affect the transport and the deposition of MB through the porous medium. Step-input experiments were carried out to measure the dye retention. The data showed a decrease in the MB adsorbed amount on the quartz, when the pH of the aqueous phase, or the temperature, decreases, or when the flow rate, or the affinity of the divalent cation (Ca2+, Cu2+, Zn2+ and Ba2+ toward the quartz surface increases. The increase in ionic strength leads to a small decrease in the MB adsorbed amount. However, the increase in temperature leads to an increase in the retained MB amount, which suggests that the adsorption of MB on the surface of quartz is endothermic in nature. The overall data indicate that, at ambient temperature, electrostatic interaction forces, which occur between the cationic organic pollutant and the negative surface of the quartz substrate, mainly control the adsorption process.

  18. Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body

    Energy Technology Data Exchange (ETDEWEB)

    Gualda, Guilherme A.R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Jr. , Alfred T.; Sutton, Stephen R.; Rivers, Mark L. (OFM Res.); (Vanderbilt); (UC)

    2013-04-08

    Supereruptions violently transfer huge amounts (100 s-1000 s km{sup 3}) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted {approx}760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

  19. A Dibutyl Phthalate Sensor Based on a Nanofiber Polyaniline Coated Quartz Crystal Monitor

    Science.gov (United States)

    Wang, You; Ding, Pengfei; Hu, Ruifen; Zhang, Jianming; Ma, Xingfa; Luo, Zhiyuan; Li, Guang

    2013-01-01

    Dibutyl phthalate (DBP) is a commonly used plasticizer and additive to adhesives, printing inks and nail polishes. Because it has been found to be a powerful reproductive and developmental toxicant, a sensor to monitor DBP in some working spaces and the environment is required. In this work polyaniline nanofibers were deposited on the electrode of a quartz crystal oscillator to form a Quartz Crystal Microbalance gas sensor. The coated quartz crystal and a non-coated quartz crystal were mounted in a sealed chamber, and their frequency difference was monitored. When DBP vapor was injected into the chamber, gas adsorption decreased the frequency of the coated quartz crystal oscillator and thereby caused an increase in the frequency difference between the two crystals. The change of the frequency difference was recorded as the sensor response. The sensor was extremely sensitive to DBP and could be easily recovered by N2 purging. A low measurement limit of 20 ppb was achieved. The morphologies of the polyaniline films prepared by different approaches have been studied by SEM and BET. How the nanofiber-structure can improve the sensitivity and stability is discussed, while its selectivity and long-term stability were investigated. PMID:23507822

  20. Autocrine abscisic acid plays a key role in quartz-induced macrophage activation.

    Science.gov (United States)

    Magnone, Mirko; Sturla, Laura; Jacchetti, Emanuela; Scarfì, Sonia; Bruzzone, Santina; Usai, Cesare; Guida, Lucrezia; Salis, Annalisa; Damonte, Gianluca; De Flora, Antonio; Zocchi, Elena

    2012-03-01

    Inhalation of quartz induces silicosis, a lung disease where alveolar macrophages release inflammatory mediators, including prostaglandin-E(2) (PGE(2)) and tumor necrosis factor α (TNF-α). Here we report the pivotal role of abscisic acid (ABA), a recently discovered human inflammatory hormone, in silica-induced activation of murine RAW264.7 macrophages and of rat alveolar macrophages (AMs). Stimulation of both RAW264.7 cells and AMs with quartz induced a significant increase of ABA release (5- and 10-fold, respectively), compared to untreated cells. In RAW264.7 cells, autocrine ABA released after quartz stimulation sequentially activates the plasma membrane receptor LANCL2 and NADPH oxidase, generating a Ca(2+) influx resulting in NFκ B nuclear translocation and PGE(2) and TNF-α release (3-, 2-, and 3.5-fold increase, respectively, compared to control, unstimulated cells). Quartz-stimulated RAW264.7 cells silenced for LANCL2 or preincubated with a monoclonal antibody against ABA show an almost complete inhibition of NFκ B nuclear translocation and PGE(2) and TNF-α release compared to controls electroporated with a scramble oligonucleotide or preincubated with an unrelated antibody. AMs showed similar early and late ABA-induced responses as RAW264.7 cells. These findings identify ABA and LANCL2 as key mediators in quartz-induced inflammation, providing possible new targets for antisilicotic therapy.

  1. Effectiveness of a Multidimensional Randomized Control Intervention to Reduce Quartz Exposure Among Construction Workers.

    Science.gov (United States)

    van Deurssen, Erik; Meijster, Tim; Oude Hengel, Karen M; Boessen, Ruud; Spaan, Suzanne; Tielemans, Erik; Heederik, Dick; Pronk, Anjoeka

    2015-10-01

    There is little evidence with respect to the effectiveness of intervention programs that focus on the reduction of occupational quartz exposure in the construction industry. This article evaluates the effectiveness of a multidimensional intervention which was aimed at reducing occupational quartz exposure among construction workers by increasing the use of technical control measures. Eight companies participating in the cluster randomized controlled trial were randomly allocated to the intervention (four companies) or control condition (four companies). The multidimensional intervention included engineering, organizational, and behavioural elements at both organizational and individual level. Full-shift personal quartz exposure measurements and detailed observations were conducted before and after the intervention among bricklayers, carpenters, concrete drillers, demolishers, and tuck pointers (n = 282). About 59% of these workers measured at baseline were reassessed during follow-up. Bayesian hierarchical models were used to evaluate the intervention effect on exposure levels. Concrete drillers in the intervention group used technical control measures, particularly water suppression, for a significantly greater proportion of the time spent on abrasive tasks during follow-up compared to baseline (93 versus 62%; P quartz exposure (73 versus 40% in the intervention and control group respectively; P quartz exposure among high exposed construction workers. © The Author 2015. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  2. Timescales of quartz crystallization and the longevity of the Bishop giant magma body.

    Science.gov (United States)

    Gualda, Guilherme A R; Pamukcu, Ayla S; Ghiorso, Mark S; Anderson, Alfred T; Sutton, Stephen R; Rivers, Mark L

    2012-01-01

    Supereruptions violently transfer huge amounts (100 s-1000 s km(3)) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ~760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

  3. Evaluation of surface roughness and bond strength of quartz fiber posts after various pre-treatments.

    Science.gov (United States)

    Akin, Gulsah E; Akin, Hakan; Sipahi, Cumhur; Piskin, Bulent; Kirmali, Omer

    2014-11-01

    Debonding at the post-adhesive interface is a major problem for quartz fiber posts. The objective of this study was to evaluate surface roughness and bond strength of quartz fiber posts after various surface treatments. Sixty-six quartz fiber posts were randomly divided into six experimental groups (n = 11) including group C, untreated (control); group SB, sandblasted; group SC, silica coated; group HF, hydrofluoric acid-etched; group N, Nd:YAG laser irradiated; group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. They were then bonded to resin cement and tensile bond strength was determined in a universal testing machine. Furthermore, two-way ANOVA and post hoc comparison tests (α = 0.05) were performed on all data. The highest mean force value was observed in group SB and followed by group E. Tukey's HSD test showed that there was no statistical difference between group SB and group E (p = 0.673). The highest mean roughness value was observed in group SB and a significant difference was found between group SB and all other groups (p quartz fiber posts and resin cement. Sandblasting or Er:YAG laser-irradiation of the surface of the quartz fiber post before cementation is recommended for increasing retention.

  4. Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition.

    Science.gov (United States)

    Carretero-Genevrier, Adrián; Gich, Martí

    2015-12-21

    This work describes the detailed protocol for preparing piezoelectric macroporous epitaxial quartz films on silicon(100) substrates. This is a three-step process based on the preparation of a sol in a one-pot synthesis which is followed by the deposition of a gel film on Si(100) substrates by evaporation induced self-assembly using the dip-coating technique and ends with a thermal treatment of the material to induce the gel crystallization and the growth of the quartz film. The formation of a silica gel is based on the reaction of a tetraethyl orthosilicate and water, catalyzed by HCl, in ethanol. However, the solution contains two additional components that are essential for preparing mesoporous epitaxial quartz films from these silica gels dip-coated on Si. Alkaline earth ions, like Sr(2+) act as glass melting agents that facilitate the crystallization of silica and in combination with cetyl trimethylammonium bromide (CTAB) amphiphilic template form a phase separation responsible of the macroporosity of the films. The good matching between the quartz and silicon cell parameters is also essential in the stabilization of quartz over other SiO2 polymorphs and is at the origin of the epitaxial growth.

  5. [Quartz-enhanced photoacoustic spectroscopy trace gas detection system based on the Fabry-Perot demodulation].

    Science.gov (United States)

    Lin, Cheng; Zhu, Yong; Wei, Wei; Zhang, Jie; Tian, Li; Xu, Zu-Wen

    2013-05-01

    An all-optical quartz-enhanced photoacoustic spectroscopy system, based on the F-P demodulation, for trace gas detection in the open environment was proposed. In quartz-enhanced photoacoustic spectroscopy (QEPAS), an optical fiber Fabry-Perot method was used to replace the conventional electronic demodulation method. The photoacoustic signal was obtained by demodulating the variation of the Fabry-Perot cavity between the quartz tuning fork side and the fiber face. An experimental system was setup. The experiment for detection of water vapour in the open environment was carried on. A normalized noise equivalent absorption coefficient of 2.80 x 10(-7) cm(-1) x W x Hz(-1/2) was achieved. The result demonstrated that the sensitivity of the all-optical quartz-enhanced photoacoustic spectroscopy system is about 2.6 times higher than that of the conventional QEPAS system. The all-optical quartz-enhanced photoacoustic spectroscopy system is immune to electromagnetic interference, safe in flammable and explosive gas detection, suitable for high temperature and high humidity environments and realizable for long distance, multi-point and network sensing.

  6. Whole grains and health: from theory to practice--highlights of The Grains for Health Foundation's Whole Grains Summit 2012.

    Science.gov (United States)

    McKeown, Nicola M; Jacques, Paul F; Seal, Chris J; de Vries, Jan; Jonnalagadda, Satya S; Clemens, Roger; Webb, Densie; Murphy, Lee Anne; van Klinken, Jan-Willem; Topping, David; Murray, Robyn; Degeneffe, Dennis; Marquart, Leonard F

    2013-05-01

    The Grains for Health Foundation's Whole Grains Summit, held May 19-22, 2012 in Minneapolis, was the first meeting of its kind to convene >300 scientists, educators, food technologists, grain breeders, food manufacturers, marketers, health professionals, and regulators from around the world. Its goals were to identify potential avenues for collaborative efforts and formulate new approaches to whole-grains research and health communications that support global public health and business. This paper summarizes some of the challenges and opportunities that researchers and nutrition educators face in expanding the knowledge base on whole grains and health and in translating and disseminating that knowledge to consumers. The consensus of the summit was that effective, long-term, public-private partnerships are needed to reach across the globe and galvanize the whole-grains community to collaborate effectively in translating whole-grains science into strategies that increase the availability and affordability of more healthful, grain-based food products. A prerequisite of that is the need to build trust among diverse multidisciplinary professionals involved in the growing, producing, marketing, and regulating of whole-grain products and between the grain and public health communities.

  7. Vertical Resolved Dust Mass Concentration and Backscatter Coefficient Retrieval of Asian Dust Plume Using Quartz Raman Channel in Lidar Measurements

    OpenAIRE

    Noh Young M.; Mueller Detlef; Shin Sungkyun

    2016-01-01

    In this work, we present a method for estimating vertical resolved mass concentration of dust immersed in Asian dust plume using Raman scattering of quartz (silicon dioxide, silica). During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profiles of the quartz backscatter coefficient. Since the Raman backscatter coefficient was connected with the Raman backscatter differential cross section a...

  8. 77 FR 76452 - Grain Inspection Advisory Committee Reestablishment

    Science.gov (United States)

    2012-12-28

    ... Doc No: 2012-31281] DEPARTMENT OF AGRICULTURE Grain Inspection, Packers and Stockyards Administration Grain Inspection Advisory Committee Reestablishment AGENCY: Grain Inspection, Packers and Stockyards... of Agriculture has reestablished the Grain Inspection, Packers and Stockyards Administration (GIPSA...

  9. Vertical Resolved Dust Mass Concentration and Backscatter Coefficient Retrieval of Asian Dust Plume Using Quartz Raman Channel in Lidar Measurements

    Directory of Open Access Journals (Sweden)

    Noh Young M.

    2016-01-01

    Full Text Available In this work, we present a method for estimating vertical resolved mass concentration of dust immersed in Asian dust plume using Raman scattering of quartz (silicon dioxide, silica. During the Asian dust period of March 15, 16, and 21 in 2010, Raman lidar measurements detected the presence of quartz, and successfully showed the vertical profiles of the quartz backscatter coefficient. Since the Raman backscatter coefficient was connected with the Raman backscatter differential cross section and the number density of quartz molecules, the mass concentration of quartz in the atmosphere can be estimated from the quartz backscatter coefficient. The weight percentage from 40 to 70 % for quartz in the Asian dust was estimated from references. The vertical resolved mass concentration of dust was estimated by quartz mass concentration and weight percentage. We also present a retrieval method to obtain dust backscatter coefficient from the mixed Asian dust and pollutant layer. OPAC (Optical Properties of Aerosol and Clouds simulations were conducted to calculate dust backscatter coefficient. The retrieved dust mass concentration was used as an input parameter for the OPAC calculations. These approaches in the study will be useful for characterizing the quartz dominated in the atmospheric aerosols and estimating vertical resolved mass concentration of dust. It will be especially applicable for optically distinguishing the dust and non-dust aerosols in studies on the mixing state of Asian dust plume. Additionally, the presented method combined with satellite observations is enable qualitative and quantitative monitoring for Asian dust.

  10. [Role of calcium activated-potassium channels in the injury to rat alveolar macrophages induced by quartz].

    Science.gov (United States)

    Li, Jun; Sun, Jingzhi; Yang, Li; Zhao, Jing; Wang, Zhenglun; Yang, Lei

    2014-01-01

    To investigate the role of calcium activated-potassium channels (KCa) in the injury to rat alveolar macrophages induced by quartz. The experiments were conducted on a rat alveolar macrophage cell line (NR8383) in vitro, where crystal silica (100 üg/ml) and amorphous silica (100 üg/ml) were used as the test substances and the cells without any treatment as negative controls. At first the effects of two kinds of quartz were compared. Then KCa special inhibitors (Paxilline for BK, Tram-34 for IK, Apamin for SK) were added in different doses to the in vitro test system with 100 üg/ml crystal quartz as matrix, to observe the function of such channels. Cell viability, lactate dehydrogenase (LDH), interleukin-1β (IL-1β) and tumor necrosis factor-a (TNF-α) were tested. Comparing to the negative control group, cell viability reduced, LDH leakage, IL-1β and TNF-α release increased significantly in the amorphous quartz group, furthermore, the effects by crystal quartz were much more serious than those by amorphous quartz, with a statistical significance (P quartz group, IK blockers (Tram-34) led to increase in cell viability significantly, with a statistical significance (P quartz in the rat alveolar macrophages cell line in vitro, which might serve as a signal in the early regulation of inflammatory responses by quartz.

  11. Quartz dissolution. I - Negative crystal experiments and a rate law. II - Theory of rough and smooth surfaces

    Science.gov (United States)

    Gratz, Andrew J.; Bird, Peter

    1993-01-01

    The range of the measured quartz dissolution rates, as a function of temperature and pOH, extent of saturation, and ionic strength, is extended to cover a wider range of solution chemistries, using the negative crystal methodology of Gratz et al. (1990) to measure the dissolution rate. A simple rate law describing the quartz dissolution kinetics above the point of zero charge of quartz is derived for ionic strengths above 0.003 m. Measurements were performed on some defective crystals, and the mathematics of step motion was developed for quartz dissolution and was compared with rough-face behavior using two different models.

  12. DEVELOPMENT OF GRAIN MARKET IN UKRAINE

    Directory of Open Access Journals (Sweden)

    Aleksandr Maslak

    2015-11-01

    Full Text Available The subject of the research is a set of theoretical, methodological and practical fundamentals of organizational and economic functioning are integrated agricultural formations in the grain market of Ukraine. The methodological basis of research is the complex analysis of economic processes in the grain market in Ukraine and the world. During research we used such methods as method of systematization and comparison, statistic, economic, balance, constructive, target-oriented, and the methods of induction and deduction, analogy and comparison. Main aim of this article is the analysis of the situation on the grain market in Ukraine, defining the role of integrated agricultural formations in this market, improving the organizational-economic mechanism of its functioning, identifies ways of improving the competitiveness of Ukraine among world exporters of grain. Using results of the studies we examined trends grain market in Ukraine; influence of businesses in grain production; analysis of constraints to improve production efficiency of grain; defined domestic (internal needs of grain in Ukraine; assessed the status and expediency transformation infrastructure of the grain market of Ukraine; defined priority directions of development of the grain market in Ukraine. As a result of the preparation of articles, it is obtained the following conclusions: Ukraine is the world's largest producers and exporters of grain, the production of integrated agricultural units to a third of the total grain; technical condition of farm does not meet the needs of production; the domestic market is unable to provide the existing demand for grain production, contributing to export growth; Ukraine has a number of problems due to increased grain production, namely the shortage of storage capacity for the storage of grain, limited performance transshipment of grain in port elevators and imperfection and depreciation of transport systems; solving the existing problems is

  13. Coarse-graining complex dynamics

    DEFF Research Database (Denmark)

    Sibani, Paolo

    2013-01-01

    Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat-tailed distribu......Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat......-tailed distribution of the waiting time between consecutive jumps. We first argue that CTRW are inadequate to describe macroscopic relaxation processes for three reasons: macroscopic variables are not self-averaging, memory effects require an all-knowing observer,and different mechanisms whereby the jumps affect......: while CTRW make use of a renewal process involving identical traps of infinite size, RD embodies a dynamical entrenchment into a hierarchy of traps which are finite in size and possess different degrees of meta-stability. We show in particular how RD produces the stretched exponential, power...

  14. Neutron peak velocity measurements at the National Ignition Facility (NIF) using novel quartz detectors

    Science.gov (United States)

    Grim, Gary; Eckart, Mark; Hartouni, Edward; Hatarik, Robert; Moore, Alastair; Root, Jaben; Sayre, Daniel; Schlossberg, David; Waltz, Cory

    2017-10-01

    In mid-2017 the NIF implemented quartz based neutron time-of-flight (nToF) detectors which have a faster and narrower impulse response function (IRF) relative to traditional scintillator detectors. In this presentation we report on comparisons between fusion neutron first moments as measured by quartz and scintillator based detectors using DT layered implosions at the NIF. We report on the change in precision presaged by the quartz converter and quantify the change in both in shot, line-of-site velocity variability. as well as, shot-to-shot variation. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-734511-DRAFT.

  15. Mathematical modeling of quartz particle melting process in plasma-chemical reactor

    Science.gov (United States)

    Volokitin, Oleg; Vlasov, Viktor; Volokitin, Gennady; Skripnikova, Nelli; Shekhovtsov, Valentin

    2016-01-01

    Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ rp ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ rp ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

  16. [Study of quartz's Roman spectrum at high pressure and room temperature].

    Science.gov (United States)

    Li, Yue; Yan, Shi-Yong; Chen, Yong

    2011-08-01

    Phase transition of quartz is widely used in the high pressure experiment as the standard of pressure correcting of the laboratory instrument. And the quartz is usually used as the pressure sensor in the experiment when the pressure is low. Christian S et al discussed the function between the pressure and the shift of quartz's Raman spectrum peak when the shift isn't exceeding 20 cm(-1). In order to extend the applying range, the authors discussed the function again using the diamond anvil cell, and used ruby as the pressure sensor which is widely used in the high pressure experiment. After discussing the function, we obtained a new function that is P(MPa) = -1.094 83E7 + 67 495.237 31 X DeltaV-138.706 91(DeltaV)2 + 0.095 04 (DeltaV)3 which is different from the Christian's function.

  17. Ab-initio molecular dynamics and vibrational Raman spectroscopy investigations of quartz polymorph at high temperature

    Science.gov (United States)

    Sediki, Hayet; Simon, Patrick; Hadjadj, Aomar; Krallafa, Abdelghani M.

    2017-09-01

    Quartz has found a wide range of applications over the past years. In the present work, the temperature dependence of microcrystalline quartz is investigated with Raman spectroscopy and DFT-based molecular dynamics simulations. We aimed to determine the structure at short and medium range distances as a function of the increasing temperature. The dynamics and the structural changes are analysed in terms of time-dependent properties, and the vibrational analysis obtained from calculated dipole trajectory and vibrational density of states (VDOS). The computed data is compared to Raman and infrared spectroscopic measurements. The approach is of a particularly great interest when we focus on the structural behaviour, and the dynamical disorder observed and characterised through geometric and thermodynamic data. The calculations confirm that the infrared and Raman signature as a function of temperature provide a sensitive analysis of the structural behaviour of quartz.

  18. Radiation on luminescent properties of quartz glasses and fiber light pipes

    CERN Document Server

    Abdurakhmanov, B S; Gulamova, R R; Alimov, R; Yuldashev, B S; Ashurov, M K; Rustamov, I R

    2002-01-01

    Paper contains the results of investigation into X-ray luminescence of KI and KU-1 quartz glasses and of various composition and size quartz fiber light pipes (FLP) gamma-irradiated within 10 sup 2 -10 sup 7 Gy dose range. On the basis of analysis of X-ray luminescence spectra of glasses and FLP and comparison of the experimental data one detected in spectra two luminescence bands within 410, 450-470 nm range. One determined dose dependences of X-ray luminescence intensity of every of these bands of luminescence and hypothesized about the nature of the relevant centers. The protective role of OH-groups in the process of radiation-induced generation of luminescence centres under gamma-irradiation of quartz glasses and FLP was confirmed experimentally

  19. Using soils for accident dosimetry: a preliminary study using optically stimulated luminescence from quartz

    DEFF Research Database (Denmark)

    Fujita, Hiroki; Jain, Mayank; Murray, Andrew S.

    2011-01-01

    The optimum conditions of preheat temperature, stimulation temperature, etc. in the single-aliquot regenerative optically stimulated luminescence (SAR OSL) method were examined specifically for measuring background dose in natural quartz extracted from soils collected around Tokai-mura in Japan....... The objective was to assess the potential of SAROSL dosimetry using soils for retrospective assessment of a radiation accident. Variation in dose with depth was also measured. The SAR data showed good reproducibility and dose recovery, and there was no evidence of fading of the quartz signal based on “delayed......, and no clear trend in dose depth profile was observed. From these results, we conclude that SAR OSL dosimetry using natural quartz extracted from soil could be used to evaluate the dose of an accident....

  20. R and D on Radiation Hard Active Media Based on Quartz Plates

    CERN Document Server

    Onel, Yasar

    2014-01-01

    The need for radiation-hard active media in particle detectors is prominently dictated by the future colliders and the future operations of the Large Hadron Collider. The areas of implementation range from calorimetry to beamline instrumentation to specialized forward detectors e.g. luminosity monitors. In this context, we developed the idea of utilizing quartz plates with various surface coating properties as the active medium for such detectors. Plain quartz is a pure Cerenkov radiator which has quite limited photostatistics. In order to improve the efficiency of the photodetection, various methods were investigated including radiation hard wavelength shifters, p-terphenyl or 4pct gallium doped zinc oxide. The readout options include direct coupling of the photodetector to the quartz plate, or fibers. We have studied various geometries and readout options and constructed calorimeter prototypes. Here we report on the results of the previous tests, and the recent developments, which enable several factors of ...

  1. Optically stimulated luminescence from quartz measured using the linear modulation technique

    DEFF Research Database (Denmark)

    Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

    2000-01-01

    The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonically...... stimulated component occurs at a shorter time. This allows the separation of the overlapping OSL components, which are assumed to originate from different traps. The LM-OSL curve from quartz shows an initial peak Followed by a broad one. Deconvolution using curve fitting has shown that the composite OSL...... curve from quartz can be approximated well by using a linear combination of first-order peaks. In addition to the three known components, i.e. fast, medium and slow components from continuous-wave-OSL studies, an additional slow component is also identified for the first time. The dose responses...

  2. Enhanced red photoluminescence of quartz by silicon nanocrystals thin film deposition

    Science.gov (United States)

    Momeni, A.; Pourgolestani, M.; Taheri, M.; Mansour, N.

    2018-03-01

    The room-temperature photoluminescence properties of silicon nanocrystals (SiNCs) thin film on a quartz substrate were investigated, which presents the red emission enhancement of quartz. We show that the photoluminescence intensity of quartz, in the wavelength range of 640-700 nm, can be enhanced as much as 15-fold in the presence of the SiNCs thin film. Our results reveal that the defect states at the SiNCs/SiO2 interface can be excited more efficiently by indirect excitation via the SiNCs, leading to the prominent red photoluminescence enhancement under the photo-excitation in the range of 440-470 nm. This work suggests a simple pathway to improve silicon-based light emitting devices for photonic applications.

  3. Quartz enhanced photoacoustic spectroscopy with a 3.38 μm antimonide distributed feedback laser.

    Science.gov (United States)

    Jahjah, Mohammad; Belahsene, Sofiane; Nähle, Lars; Fischer, Marc; Koeth, Johannes; Rouillard, Yves; Vicet, Aurore

    2012-07-01

    A system for gas sensing based on the quartz-enhanced photoacoustic spectroscopy technique has been developed. It makes use of a quantum well distributed feedback (DFB) laser diode emitting at 3.38 μm. This laser emits near room temperature in the continuous wave regime. A spectrophone, consisting of a quartz tuning fork and two steel microresonators were used. Second derivative wavelength modulation detection is used to perform low concentration measurements. The sensitivity and the linearity of the Quartz enhanced photoacoustic spectroscopy (QEPAS) sensor were studied. A normalized noise equivalent absorption coefficient of 4.06×10(-9) cm(-1)·W/Hz(1/2) was achieved.

  4. Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz

    Science.gov (United States)

    Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.

    2015-01-01

    Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.

  5. Replacement of filters for respirable quartz measurement in coal mine dust by infrared spectroscopy.

    Science.gov (United States)

    Farcas, Daniel; Lee, Taekhee; Chisholm, William P; Soo, Jhy-Charm; Harper, Martin

    2016-01-01

    The objective of this article is to compare and characterize nylon, polypropylene (PP), and polyvinyl chloride (PVC) membrane filters that might be used to replace the vinyl/acrylic co-polymer (DM-450) filter currently used in the Mine Safety and Health Administration (MSHA) P-7 method (Quartz Analytical Method) and the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods 7603 method (QUARTZ in coal mine dust, by IR re-deposition). This effort is necessary because the DM-450 filters are no longer commercially available. There is an impending shortage of DM-450 filters. For example, the MSHA Pittsburgh laboratory alone analyzes annually approximately 15,000 samples according to the MSHA P-7 method that requires DM-450 filters. Membrane filters suitable for on-filter analysis should have high infrared (IR) transmittance in the spectral region 600-1000 cm(-1). Nylon (47 mm, 0.45 µm pore size), PP (47 mm, 0.45 µm pore size), and PVC (47 mm, 5 µm pore size) filters meet this specification. Limits of detection and limits of quantification were determined from Fourier transform infrared spectroscopy (FTIR) measurements of blank filters. The average measured quartz mass and coefficient of variation were determined from test filters spiked with respirable α-quartz following MSHA P-7 and NIOSH 7603 methods. Quartz was also quantified in samples of respirable coal dust on each test filter type using the MSHA and NIOSH analysis methods. The results indicate that PP and PVC filters may replace the DM-450 filters for quartz measurement in coal dust by FTIR. PVC filters of 5 µm pore size seemed to be suitable replacement although their ability to retain small particulates should be checked by further experiment.

  6. Respirable quartz dust exposure and airway obstruction: a systematic review and meta-analysis.

    Science.gov (United States)

    Brüske, Irene; Thiering, Elisabeth; Heinrich, Joachim; Huster, Katharina M; Nowak, Dennis

    2014-08-01

    Studies on exposure to respirable quartz dust at the workplace and the development of chronic obstructive pulmonary disease (COPD) were selected into a systematic review and meta-analysed to obtain an overall estimate of forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) reduction. PubMed and Embase were searched from 1970 to 2010. In total, 257 cross-sectional and longitudinal studies were identified that reported on inorganic dust exposure and had available lung function data. Of the 55 publications which met our inclusion criteria, 11 reported on associations with occupational exposure to respirable quartz dust. The combined average effect estimate of respirable quartz dust on spirometric parameters was obtained using a random effects model meta-analysis. Between-study heterogeneity was assessed via the I(2) statistic. Most studies found a significant negative association of FEV1 and FEV1/FVC related to increasing exposure to crystalline quartz at the workplace. One study found an effect only for smokers, and one did not observe such an effect at all. The meta-analysis of cross-sectional studies showed that the mean ratio FEV1 to FVC was reduced and FEV1 of workers exposed to respirable quartz dust was 4.6% less than predicted compared with workers with no/low exposure. Both results showed a statistically significant difference. Occupational exposure to respirable quartz dust was associated with a statistically significant decrease in FEV1 and FEV1/FVC, revealing airway obstruction consistent with COPD. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  7. Application of The Titanium-In-Quartz Thermobarometer to Eclogites from The Biga Peninsula, NW Turkey

    Science.gov (United States)

    Şengün, Firat; Zack, Thomas

    2016-10-01

    Eclogites crop out in the Çamlica metamorphics and beneath the Çetmi melange as a tectonic slice in the Biga Peninsula in northwest Turkey. The Çamlica metamorphics occur in the westernmost part of the Biga Peninsula and are tectonically separated from the Denizgoren ophiolite in the west by the Ovacik fault. The Çetmi melange found on the southern part of the Biga Peninsula is mainly composed of various types of blocks within a detritic matrix. The high-P assemblages in eclogite consist of omphacite + garnet + epidote + glaucophane + quartz + phengite. Typical accessory minerals are rutile, zircon and sphene. Ti-in-quartz thermobarometer (TitaniQ) was applied on eclogites from the Biga Peninsula. The P-T dependencies of Ti-in-quartz solubility can be combined with P-T dependencies of Zr-in-rutile solubility to estimate pressure and temperature of crystallization. Titanium concentrations in quartz from the Çamlica metamorphics range from 0.26 to 0.91 ppm. Zirconium concentrations in rutile range from 26 to 64 ppm. However, Ti contents in quartz from the Çetmi melange vary from 0.47 to 2.19 ppm. Zr contents in rutile range between 50 and 150 ppm. Regional high-P metamorphism with peak conditions of 551 ± 5 oC and 21.5 ± 0.3 kbar in eclogite from the Çamlica region and 624 ± 17 oC and 22.6 ± 1.6 kbar in eclogite from the Çetmi region. Ti- in-quartz thermobarometer gives precise and comprehensible pressure and temperature values when using the Zr-in-rutile thermobarometer, which could be an advantage over classical methods.

  8. Clay, Water, and Salt: Controls on the Permeability of Fine-Grained Sedimentary Rocks.

    Science.gov (United States)

    Bourg, Ian C; Ajo-Franklin, Jonathan B

    2017-09-19

    The ability to predict the permeability of fine-grained soils, sediments, and sedimentary rocks is a fundamental challenge in the geosciences with potentially transformative implications in subsurface hydrology. In particular, fine-grained sedimentary rocks (shale, mudstone) constitute about two-thirds of the sedimentary rock mass and play important roles in three energy technologies: petroleum geology, geologic carbon sequestration, and radioactive waste management. The problem is a challenging one that requires understanding the properties of complex natural porous media on several length scales. One inherent length scale, referred to hereafter as the mesoscale, is associated with the assemblages of large grains of quartz, feldspar, and carbonates over distances of tens of micrometers. Its importance is highlighted by the existence of a threshold in the core scale mechanical properties and regional scale energy uses of shale formations at a clay content X clay ≈ 1/3, as predicted by an ideal packing model where a fine-grained clay matrix fills the gaps between the larger grains. A second important length scale, referred to hereafter as the nanoscale, is associated with the aggregation and swelling of clay particles (in particular, smectite clay minerals) over distances of tens of nanometers. Mesoscale phenomena that influence permeability are primarily mechanical and include, for example, the ability of contacts between large grains to prevent the compaction of the clay matrix. Nanoscale phenomena that influence permeability tend to be chemomechanical in nature, because they involve strong impacts of aqueous chemistry on clay swelling. The second length scale remains much less well characterized than the first, because of the inherent challenges associated with the study of strongly coupled nanoscale phenomena. Advanced models of the nanoscale properties of fine-grained media rely predominantly on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, a mean field

  9. Theoretical analysis of a resonant quartz-enhanced photoacoustic spectroscopy sensor

    Science.gov (United States)

    Aoust, Guillaume; Levy, Raphael; Raybaut, Myriam; Godard, Antoine; Melkonian, Jean-Michel; Lefebvre, Michel

    2017-02-01

    In this paper, we report the first analytical model for quartz-enhanced photoacoustic spectroscopy in combination with an acoustic resonator. A generalized fundamental equation is proposed to model the photoacoustic effect, taking into account the coupling between the tuning fork and the surrounding fluid. The analytical signal-to-noise ratio is derived, yielding a direct physical insight with respect to the system design. Experimental behaviors are very well reproduced, and numerical finite elements methods are implemented to successfully confirm the relevance of our approach. We also provide a detailed explanation of the coupling dynamics between the quartz tuning fork and the acoustically resonant tube.

  10. BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

    OpenAIRE

    Raharjo Raharjo

    2010-01-01

    An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed metho...

  11. Molecular dynamics simulation of siderite-hematite-quartz flotation with sodium oleate

    Science.gov (United States)

    Li, Lixia; Hao, Haiqing; Yuan, Zhitao; Liu, Jiongtian

    2017-10-01

    Models of sodium oleate adsorption on siderite, hematite and quartz were investigated by molecular dynamic simulation, respectively. Surface energy was calculated to confirm the cleavage plan of hematite and quartz. Both natural cleavage plane of siderite and calculated plane were used to investigate the flotation of the three minerals. Based on the molecular simulation in solution with water as medium, adsorption quantity and interaction capability of oleate ions on the three minerals indicated that siderite could be collected efficiently by sodium oleate at neutral pH. Results of flotation experiments were further demonstrated by analysis of relative concentration of carbon atoms and oxygen atoms.

  12. The quartz crystal microbalance in soft matter research fundamentals and modeling

    CERN Document Server

    Johannsmann, Diethelm

    2014-01-01

    This book describes the physics of the second-generation quartz crystal microbalance (QCM), a fundamental method of analysis for soft matter at interfaces.From a device for measuring film thickness in vacuum, the quartz crystal microbalance (QCM) has in the past two decades evolved into a versatile instrument for analyzing soft matter at solid/liquid and solid/gas interfaces that found applications in diverse fields including the life sciences, material science, polymer research and electrochemistry. As a consequence of this success, the QCM is now being used by scientists with a wide variety

  13. Quartz measurement in coal dust with high-flow rate samplers: laboratory study.

    Science.gov (United States)

    Lee, Taekhee; Lee, Eun Gyung; Kim, Seung Won; Chisholm, William P; Kashon, Michael; Harper, Martin

    2012-05-01

    A laboratory study was performed to measure quartz in coal dust using high-flow rate samplers (CIP10-R, GK2.69 cyclone, and FSP10 cyclone) and low-flow rate samplers [10-mm nylon and Higgins-Dewell type (BGI4L) cyclones] and to determine whether an increased mass collection from high-flow rate samplers would affect the subsequent quartz measurement by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analytical procedures. Two different sizes of coal dusts, mass median aerodynamic diameter 4.48 μm (Coal Dust A) and 2.33 μm (Coal Dust B), were aerosolized in a calm air chamber. The mass of coal dust collected by the samplers was measured gravimetrically, while the mass of quartz collected by the samplers was determined by FTIR (NIOSH Manual of Analytical Method 7603) and XRD (NIOSH Manual of Analytical Method 7500) after one of two different indirect preparations. Comparisons between high-flow rate samplers and low-flow rate samplers were made by calculating mass concentration ratios of coal dusts, net mass ratios of coal dusts, and quartz net mass. Mass concentrations of coal dust from the FSP10 cyclone were significantly higher than those from other samplers and mass concentrations of coal dust from 10-mm nylon cyclone were significantly lower than those from other samplers, while the CIP10-R, GK2.69, and BGI4L samplers did not show significant difference in the comparison of mass concentration of coal dusts. The BGI4L cyclone showed larger mass concentration of ∼9% compared to the 10-mm nylon cyclone. All cyclones provided dust mass concentrations that can be used in complying with the International Standard Organization standard for the determination of respirable dust concentration. The amount of coal dust collected from the high-flow rate samplers was found to be higher with a factor of 2-8 compared to the low-flow rate samplers but not in direct proportion of increased flow rates. The high-flow rate samplers collected more quartz compared to

  14. Adhesion of alkane as a functional group on muscovite and quartz

    DEFF Research Database (Denmark)

    Juhl, Klaus; Pedersen, Christian Schack; Bovet, Nicolas Emile

    2014-01-01

    The interactions between mineral surfaces and organic molecules in water control many processes in nature and in the production of modern materials. To improve the understanding of fluid-surface interactions, we investigated the interface behavior of quartz and muscovite, a model for clay minerals......, i.e., 400 ± 77 pN, was considerably larger than for quartz, 84 ± 15 pN, which fits with the different surface structure and composition of the two minerals. We propose two mechanisms to explain these results: (1) cations that are structured in the solution and on the surface remain associated...

  15. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ankjaergaard, C.

    2010-02-15

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

  16. Evaluation of the flexural strength of carbon, quartz, and glass fiber-based posts

    OpenAIRE

    Sita Rama Raju; Krishna Rao Kilaru; Kidyoor Krishnamurthy Haridas; Balaram Naik; Krishnaprasad Shetty; Satish Sarvepalli Venkata

    2014-01-01

    Objectives: This study was done to evaluate the flexural strength of carbon, quartz, and glass fiber posts by means of three-point bending test. Materials and Methods: Thirty pre-fabricated fiber posts were used and divided into three groups. Group I carbon fiber posts (C-Post), group II quartz fiber post (Aestheti Plus), group III glass fiber post (Para Post White) Ten posts (N = 10) were used for each experimental group and were measured with digital caliper before test accomplishment. The ...

  17. Initial results on 5 MHz quartz oscillators equipped with BVA resonators

    Science.gov (United States)

    Besson, R. J.; Emmons, D. A.

    1979-01-01

    The techniques of fabricating BVA resonators are discussed in terms of aging, amplitude-frequency effect, and acceleration sensitivity. Results on 5 MHz resonators concerning aging versus drive level, reduced amplitude-frequency effect, frequency and phase stability performance, and frequency retrace following power interruption are presented. It is indicated that a zero aging rate is possible at a drive level which depends on the qaurtz material used. For natural AT quartz, a level of 70 to 90 micro W appears to be optimum, and for SC quartz approximately 160 micro W.

  18. Allan Deviation Plot as a Tool for Quartz-Enhanced Photoacoustic Sensors Noise Analysis.

    Science.gov (United States)

    Giglio, Marilena; Patimisco, Pietro; Sampaolo, Angelo; Scamarcio, Gaetano; Tittel, Frank K; Spagnolo, Vincenzo

    2016-04-01

    We report here on the use of the Allan deviation plot to analyze the long-term stability of a quartz-enhanced photoacoustic (QEPAS) gas sensor. The Allan plot provides information about the optimum averaging time for the QEPAS signal and allows the prediction of its ultimate detection limit. The Allan deviation can also be used to determine the main sources of noise coming from the individual components of the sensor. Quartz tuning fork thermal noise dominates for integration times up to 275 s, whereas at longer averaging times, the main contribution to the sensor noise originates from laser power instabilities.

  19. Stimulated Raman rotational photoacoustic spectroscopy using a quartz tuning fork and femtosecond excitation

    Science.gov (United States)

    Schippers, W.; Gershnabel, E.; Burgmeier, J.; Katz, O.; Willer, U.; Averbukh, I. S.; Silberberg, Y.; Schade, W.

    2011-11-01

    Molecular alignment of linear molecules (O2, N2, CO2 and CO) is measured photoacoustically in the gas phase. The rotational excitation is accomplished using a simple femtosecond stimulated Raman excitation scheme, employing two femtosecond pulses with variable delay between the pulses. Molecular alignment is determined directly by measuring the energy dumped into the gas by quartz-enhanced photoacoustic spectroscopy (QEPAS), utilizing a quartz tuning fork as a sensitive photoacoustic transducer. The experimental results demonstrate for the first time the use of a tuning fork for resonant photoacoustic detection of Raman spectra excited by femtosecond double pulses and match both simulation and literature values.

  20. Design and Optimization of QTF Chopper for Quartz-Enhanced Photoacoustic Spectroscopy

    Science.gov (United States)

    Dong, Lei; Liu, Yanyan; Zheng, Huadan; Liu, Xiaoli; Wu, Hongpeng; Ma, Weiguang; Zhang, Lei; Yin, Wangbao; Jia, Suotang

    2015-06-01

    A novel quartz-tuning-fork (QTF) chopper was developed for quartz-enhanced photoacoustic spectroscopy (QEPAS). Unlike the conventional wavelength-modulation-based QEPAS, the QTF chopper chops the continuous wave excitation light into a sequence of light pulses, which realizes the amplitude-modulation (AM)-based QEPAS. In order to reduce the chopping noise and to make the resonance frequency of the QTF chopper perfectly match that of the detection QTF, a careful design and optimization were implemented. The performance of the AM-based QEPAS sensor for detection was also evaluated in detail.