Science.gov

Sample records for african mcs anvils

  1. Leading and Trailing Anvil Clouds of West African Squall Lines

    NASA Technical Reports Server (NTRS)

    Centrone, Jasmine; Houze, Robert A.

    2011-01-01

    The anvil clouds of tropical squall-line systems over West Africa have been examined using cloud radar data and divided into those that appear ahead of the leading convective line and those on the trailing side of the system. The leading anvils are generally higher in altitude than the trailing anvil, likely because the hydrometeors in the leading anvil are directly connected to the convective updraft, while the trailing anvil generally extends out of the lower-topped stratiform precipitation region. When the anvils are subdivided into thick, medium, and thin portions, the thick leading anvil is seen to have systematically higher reflectivity than the thick trailing anvil, suggesting that the leading anvil contains numerous larger ice particles owing to its direct connection to the convective region. As the leading anvil ages and thins, it retains its top. The leading anvil appears to add hydrometeors at the highest altitudes, while the trailing anvil is able to moisten a deep layer of the atmosphere.

  2. Improved Anvil Forecasting

    NASA Technical Reports Server (NTRS)

    Lambert, Winifred C.

    2000-01-01

    This report describes the outcome of Phase 1 of the AMU's Improved Anvil Forecasting task. Forecasters in the 45th Weather Squadron and the Spaceflight Meteorology Group have found that anvil forecasting is a difficult task when predicting LCC and FR violations. The purpose of this task is to determine the technical feasibility of creating an anvil-forecasting tool. Work on this study was separated into three steps: literature search, forecaster discussions, and determination of technical feasibility. The literature search revealed no existing anvil-forecasting techniques. However, there appears to be growing interest in anvils in recent years. If this interest continues to grow, more information will be available to aid in developing a reliable anvil-forecasting tool. The forecaster discussion step revealed an array of methods on how better forecasting techniques could be developed. The forecasters have ideas based on sound meteorological principles and personal experience in forecasting and analyzing anvils. Based on the information gathered in the discussions with the forecasters, the conclusion of this report is that it is technically feasible at this time to develop an anvil forecasting technique that will significantly contribute to the confidence in anvil forecasts.

  3. Advanced Diamond Anvil Techniques (Customized Diamond Anvils)

    SciTech Connect

    Weir, S

    2009-02-11

    A complete set of diamond-based fabrication tools now exists for making a wide range of different types of diamond anvils which are tailored for various high-P applications. Current tools include: CVD diamond deposition (making diamond); Diamond polishing, laser drilling, plasma etching (removal of diamond); and Lithography, 3D laser pantography (patterning features onto diamond); - Metal deposition (putting electrical circuits and metal masks onto diamond). Current applications include the following: Electrical Conductivity; Magnetic Susceptibility; and High-P/High-T. Future applications may include: NMR; Hall Effect; de Haas - Shubnikov (Fermi surface topology); Calorimetry; and thermal conductivity.

  4. Global Variability of Mesoscale Convective System Anvil Structure from A-Train Satellite Data

    NASA Technical Reports Server (NTRS)

    Yuan, Jian; Houze, Robert A.

    2010-01-01

    Mesoscale convective systems (MCSs) in the tropics produce extensive anvil clouds, which significantly affect the transfer of radiation. This study develops an objective method to identify MCSs and their anvils by combining data from three A-train satellite instruments: Moderate Resolution Imaging Spectroradiometer (MODIS) for cloud-top size and coldness, Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) for rain area size and intensity, and CloudSat for horizontal and vertical dimensions of anvils. The authors distinguish three types of MCSs: small and large separated MCSs and connected MCSs. The latter are MCSs sharing a contiguous rain area. Mapping of the objectively identified MCSs shows patterns of MCSs that are consistent with previous studies of tropical convection, with separated MCSs dominant over Africa and the Amazon regions and connected MCSs favored over the warm pool of the Indian and west Pacific Oceans. By separating the anvil from the raining regions of MCSs, this study leads to quantitative global maps of anvil coverage. These maps are consistent with the MCS analysis, and they lay the foundation for estimating the global radiative effects of anvil clouds. CloudSat radar data show that the modal thickness of MCS anvils is about 4-5 km. Anvils are mostly confined to within 1.5-2 times the equivalent radii of the primary rain areas of the MCSs. Over the warm pool, they may extend out to about 5 times the rain area radii. The warm ocean MCSs tend to have thicker non-raining and lightly raining anvils near the edges

  5. Dust Science with SPICA/MCS

    NASA Astrophysics Data System (ADS)

    Sakon, I.; Onaka, T.; Kataza, H.; Wada, T.; Sarugaku, Y.; Matsuhara, H.; Nakagawa, T.; Kobayashi, N.; Kemper, C.; Ohyama, Y.; Matsumoto, T.; Seok, J. Y.

    Mid-Infrared Camera and Spectrometers (MCS) is one of the Focal-Plane Instruments proposed for the SPICA mission in the pre-project phase. SPICA MCS is equipped with two spectrometers with different spectral resolution powers (R=λ /δ λ ); medium-resolution spectrometer (MRS) which covers 12-38µ m with R≃1100-3000, and high-resolution spectrometer (HRS) which covers either 12-18µ m with R≃30000. MCS is also equipped with Wide Field Camera (WFC), which is capable of performing multi-objects grism spectroscopy in addition to the imaging observation. A small slit aperture for low-resolution slit spectroscopy is planned to be placed just next to the field of view (FOV) aperture for imaging and slit-less spectroscopic observation. MCS covers an important part of the core spectral range of SPICA and, complementary with SAFARI (SpicA FAR-infrared Instrument), can do crucial observations for a number of key science cases to revolutionize our understanding of the lifecycle of dust in the universe. In this article, the latest design specification and the expected performance of the SPICA/MCS are introduced. Key science cases that should be targetted by SPICA/MCS have been discussed by the MCS science working group. Among such science cases, some of those related to dust science are briefly introduced.

  6. Cohort profile: UK Millennium Cohort Study (MCS).

    PubMed

    Connelly, Roxanne; Platt, Lucinda

    2014-12-01

    The UK Millennium Cohort Study (MCS) is an observational, multidisciplinary cohort study that was set up to follow the lives of children born at the turn of the new century. The MCS is nationally representative and 18 552 families (18 827 children) were recruited to the cohort in the first sweep. There have currently been five main sweeps of data collection, at ages 9 months and 3, 5, 7 and 11 years. A further sweep of data collection is planned for age 14 years. A range of health-related data have been collected as well as measures concerning child development, cognitive ability and educational attainment. The data also include a wealth of information describing the social, economic and demographic characteristics of the cohort members and their families. In addition, the MCS data have been linked to administrative data resources including health records. The MCS provides a unique and valuable resource for the analysis of health outcomes and health inequalities. The MCS data are freely available to bona fide researchers under standard access conditions via the UK Data Service (http://ukdataservice.ac.uk) and the MCS website provides detailed information on the study (http://www.cls.ioe.ac.uk/mcs). PMID:24550246

  7. Vertical Structures of Anvil Clouds of Tropical Mesoscale Convective Systems Observed by CloudSat

    NASA Technical Reports Server (NTRS)

    Yuan, J.; Houze, R. A., Jr.; Heymsfield, A.

    2011-01-01

    A global study of the vertical structures of the clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the CloudSat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6--8 and 1--3 km. High-topped clouds extend outward from raining cores of MCSs to form anvil clouds. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS anvil clouds vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil clouds close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level cloud structure around the tropics.

  8. Vertical Structures of Anvil Clouds of Tropical Mesoscale Convective Systems Observed by CloudSat

    NASA Technical Reports Server (NTRS)

    Hence, Deanna A.; Houze, Robert A.

    2011-01-01

    A global study of the vertical structures of the clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the CloudSat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6 8 and 1 3 km. High-topped clouds extend outward from raining cores of MCSs to form anvil clouds. Closest to the raining cores, the anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of anvil clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS anvil clouds vary little across the tropics, except that (i) in continental MCS anvils, broader distributions of reflectivity occur at the uppermost levels in the portions closest to active raining areas; (ii) the frequency of occurrence of stronger reflectivity in the upper part of anvils decreases faster with increasing distance in continental MCSs; and (iii) narrower-peaked ridges are prominent in reflectivity histograms of thick anvil clouds close to the raining areas of connected MCSs (superclusters). These global results are consistent with observations at ground sites and aircraft data. They present a comprehensive test dataset for models aiming to simulate process-based upper-level cloud structure around the tropics.

  9. Heating rates in tropical anvils

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.; Valero, Francisco P. J.; Pfister, Leonhard; Liou, Kuo-Nan

    1988-01-01

    The interaction of infrared and solar radiation with tropical cirrus anvils is addressed. Optical properties of the anvils are inferred from satellite observations and from high-altitude aircraft measurements. An infrared multiple-scattering model is used to compute heating rates in tropical anvils. Layer-average heating rates in 2 km thick anvils were found to be on the order of 20 to 30 K/day. The difference between heating rates at cloud bottom and cloud top ranges from 30 to 200 K/day, leading to convective instability in the anvil. The calculations are most sensitive to the assumed ice water content, but also are affected by the vertical distribution of ice water content and by the anvil thickness. Solar heating in anvils is shown to be less important than infrared heating but not negligible. The dynamical implications of the computed heating rates are also explored and it is concluded that the heating may have important consequences for upward mass transport in the tropics. The potential impact of tropical cirrus on the tropical energy balance and cloud forcing are discussed.

  10. Tropical Anvil Cirrus Microphysics

    NASA Astrophysics Data System (ADS)

    Heymsfield, A.; Bansemer, A.; Schmitt, C.; Baumgardner, D.; Poellot, M.; Twohy, C.; Weinstock, E. M.; Smith, J. T.; Sayres, D.; Avallone, L.; Hallar, G.

    2003-12-01

    This study synthesizes data collected during a number of field campaigns by in-situ aircraft to characterize the microphysical properties of tropical, convectively-generated cirrus. The field campaigns include the Tropical Rain Measuring Mission KWAJEX campaign near Kwajalein, M. I., KAMP (the Keys Area Microphysics Project) and the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE), both over southern Florida, and CAMEX-4 (the fourth convection and moisture experiment), studying hurricanes off the east coast of Florida. The measurements include particle size distribution and particle shape information, direct measurements of the condensed water content (CRYSTAL-FACE), and radar imagery. We examine the temperature dependence and vertical variability of the ice water content (IWC), extinction, and effective radii, and deduce the ensemble-mean ice particle densities. Data obtained in quiescent regions outside of convection are compared to observations within convective cells. The relationship between the properties of the particle size distributions and proximity to convection are examined. The IWCs show a strong temperature dependence and dependence on distance below cloud top. The IWCs are larger in the convective regions than in the quiescent regions, and the particle size distributions are markedly broader. Ensemble-mean ice particle densities are a strong function of the breadth of the particle size distributions.

  11. S1 guideline: microscopically controlled surgery (MCS).

    PubMed

    Löser, Christoph R; Rompel, Rainer; Möhrle, Matthias; Häfner, Hans-Martin; Kunte, Christian; Hassel, Jessica; Hohenleutner, Ulrich; Podda, Maurizio; Sebastian, Günther; Hafner, Jürg; Kaufmann, Roland; Breuninger, Helmut

    2015-09-01

    When using procedures that enable complete examination of surgical margins (3D histology), microscopically controlled surgery (MCS) represents a safe and proven method to confirm R0 resection of infiltrating tumors, especially at problematic sites, while preserving the adjacent tissue. This allows for excellent or good aesthetic results that are superior (cryosurgery, short-range irradiation) or equivalent (PDT) to nonsurgical and less safe procedures (PDT). PMID:26882393

  12. Toward an improved understanding of MCS propagation

    NASA Astrophysics Data System (ADS)

    Peters, J. M.

    2015-12-01

    Processes that drive the propagation of elevated mesoscale convective systems (MCSs) have been the topic of a growing body of recent research. Elevated MCSs are responsible for a large percentage of warm season rainfall in the continental United States, and produce flash floods more frequently than other modes of convection. A comprehensive understanding of the dynamics of MCS propagation is important, since propagation sometimes opposes other environmental forces that influence MCS motion. This leads to nearly stationary MCSs that produce prolific local rainfall totals. The ingredients-based Propagation index (IPI) is introduced in this research. IPI is defined as the normalized product of horizontal warm thermal advection (a proxy for lifting), convective available potential energy (CAPE), and relative humidity. Horizontal plots of IPI are useful in identifying regions of probable convective initiation, including the intersections between potentially unstable flow and outflow boundaries, regions of mesoscale lift along the nose of the low-level jet, convectively induced gravity waves, and frontogenesis. Effective inflow-layer shear vectors are also introduced, and found to be useful for scenarios where IPI does yield predictive insight, such as the traditional "RKW" scenario where the forward propagation of an MCS is driven by thunderstorm outflow. It is argued that horizontal maps of IPI and EILS vectors will contribute significantly to short-term (e.g. 1-2 hr) predictions of the movement of MCSs, and to the subsequent assessment of their potential for flash flood production.

  13. Heating rates in tropical anvils

    NASA Technical Reports Server (NTRS)

    Ackerman, T. P.; Valero, F. P. J.; Liou, K.-N.

    1986-01-01

    An IR radiative transfer model for cirrus clouds was developed on the basis of data acquired with a U-2 aircraft. The emission and scattering of radiation was expressed with a two-stream algorithm that considered the cloud in 10 layers. Exponential sums were employed to quantify gaseous absorption by H2O, CO2 and O3 over the IR spectrum of 4.5-250 microns. Ice water content had the greatest impact on radiative heating of the high altitude anvils, although the vertical extent of the anvil and the cloudiness of the underlying atmosphere were also important.

  14. Anvil for Flaring PCB Guide Pins

    NASA Technical Reports Server (NTRS)

    Winn, E.; Turner, R.

    1985-01-01

    Spring-loaded anvil results in fewer fractured pins. New anvil for flaring guide pins in printed-circuit boards absorbs approximately 80 percent of press force. As result fewer pins damaged, and work output of flaring press greatly increased.

  15. Raman Lidar Observations of a MCS in the frame of the Convective and Orographically-induced Precipitation Study

    NASA Astrophysics Data System (ADS)

    Di Girolamo, Paolo; Bhawar, Rohini; Summa, Donato; Di Iorio, Tatiana; Demoz, Belay B.

    2009-03-01

    The Raman lidar system BASIL was deployed in Achern (Supersite R, Lat: 48.64° N, Long: 8.06° E, Elev.: 140 m) in the frame of the Convective and Orographically-induced Precipitation Study. On 20 July 2007 a frontal zone passed over the COPS region, with a Mesoscale Convective System (MCS) imbedded in it. BASIL was operated continuously during this day, providing measurements of temperature, water vapour, particle backscattering coefficient at 355, 532 and 1064 nm, particle extinction coefficient at 355 and 532 nm and particle depolarization at 355 and 532 nm. The thunderstorm approaching determined the lowering of the anvil clouds, which is clearly visible in the lidar data. A cloud deck is present at 2 km, which represents a mid-level outflow from the thunderstorm/MCS. The mid-level outflow spits out hydrometeor-debris (mostly virga) and it is recycled back into it. The MCS modified the environment at 1.6-2.5 km levels directly (outflow) and the lower levels through the virga/precipitation. Wave structures were observed in the particle backscatter data. The wave activity seems to be a reflection of the shear that is produced by the MCS and the inflow environmental wind. Measurements in terms of particle backscatter and water vapour mixing ratio are discussed to illustrate the above phenomena.

  16. Evolution of a Florida Cirrus Anvil

    NASA Technical Reports Server (NTRS)

    Garrett, T. J.; Navarro, B.C.; Twohy, C. H.; Jensen, E. J.; Bui, P. T.; Baumgardner, D. G.; Gerber, H.; Herman, R. L.; Heymsfield, A. J.; Lawson, P.; Minnis, P.; Nguyen, L.; Poellot, M.; Pope, S. K.; Valero, F. P. J.; Weinstock, E. M.

    2005-01-01

    This paper presents a detailed study of a single thunderstorm anvil cirrus cloud measured on 21 July 2002 near southern Florida during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers--Florida Area Cirrus Experiment (CRYSTAL-FACE). NASA WB-57F and University of North Dakota Citation aircraft tracked the microphysical and radiative development of the anvil for 3 h. Measurements showed that the cloud mass that was advected downwind from the thunderstorm was separated vertically into two layers: a cirrus anvil with cloud-top temperatures of -45?C lay below a second, thin tropopause cirrus (TTC) layer with the same horizontal dimensions as the anvil and temperatures near -70?C. In both cloud layers, ice crystals smaller than 50 ?m across dominated the size distributions and cloud radiative properties. In the anvil, ice crystals larger than 50 ?m aggregated and precipitated while small ice crystals increasingly dominated the size distributions; as a consequence, measured ice water contents and ice crystal effective radii decreased with time. Meanwhile, the anvil thinned vertically and maintained a stratification similar to its environment. Because effective radii were small, radiative heating and cooling were concentrated in layers approximately 100 m thick at the anvil top and base. A simple analysis suggests that the anvil cirrus spread laterally because mixing in these radiatively driven layers created horizontal pressure gradients between the cloud and its stratified environment. The TTC layer also spread but, unlike the anvil, did not dissipate--perhaps because the anvil shielded the TTC from terrestrial infrared heating. Calculations of top-of-troposphere radiative forcing above the anvil and TTC showed strong cooling that tapered as the anvil evolved.

  17. Multiple Chemical Sensitivity (MCS) - Scientific and Public-Health Aspects

    PubMed Central

    Schwenk, Michael

    2004-01-01

    Multiple Chemical Sensitivity (MCS) is a phenomenon which the ENT-doctor should be familiar with. It has its roots in the description of a syndrome in 1987. A worker spilled chemicals at his workplace and from then on he reacted highly sensitive to chemicals. Today, there are many people who explain their complaints with self-suspected MCS. Various pathopysiological models have been proposed, including toxicological, immunological or behaviorial models. But no-one could be proved so far. Since controlled provocation tests have also provided unclear results, an increasing number of doctors assumes today, that MCS reflects a psychic condition. In 1996, an expert team of the WHO has suggested the renaming of MCS to "idiopathic environmental illness" (IEI). However, other doctors still assume a chemical cause. Since there are neither straightforward diagnostic methods to proof MCS, nor reliable therapeutic concepts, treatment of MCS-patients is usually difficult. The MCS-debate (somatic vs psychic causes) seems to reflect the dilemma of the medical profession today, that somatic disorders of known origin can be well treated, whereas the increasing number of psychosomatic/ somatoform disorders is often resistant to medical help. The ENT-doctor should pay attention to changes of the nasal mucous membrane, nasal resistance and the sense of smell. Moreover he should know about the peculiarities of MCS-patients. The manuscript describes the present knowledge and state of discussion with special regard to the situation in Germany. PMID:22073047

  18. Double bevel construction of a diamond anvil

    DOEpatents

    Moss, William C.

    1988-01-01

    A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached.

  19. Double bevel construction of a diamond anvil

    DOEpatents

    Moss, W.C.

    1988-10-11

    A double or multiple bevel culet geometry is used on a diamond anvil in a high pressure cell apparatus to provide increased sample pressure and stability for a given force applied to the diamond tables. Double or multiple bevel culet geometries can also be used for sapphire or other hard crystal anvils. Pressures up to and above 5 Megabars can be reached. 8 figs.

  20. Testing the MCS Deconvolution Algorithm on Infrared Data

    NASA Astrophysics Data System (ADS)

    Egan, M.

    Magain, Courbin and Sohy (MCS 1998, AJ, 494, 472) proposed a two-channel (separable point source and extended background) method for astronomical image deconvolution. Unlike the two-channel Richardson-Lucy algorithm, the MCS method does not require prior knowledge of the point source amplitudes and positions. MCS have claimed that their method produces accurate astrometry and photometry in crowded fields and in the presence of variable backgrounds. This paper compares MSX 8 micron Galactic plane images deconvolved via the MCS method with Spitzer Space Telescope IRAC 8 micron images of the same regions. The improved sampling and final image PSF for the deconvolved MSX image is chosen to match the Spitzer observation. In the parlance of MCS, this determines the light distribution for an 85 cm telescope (Spitzer) by deconvolving data taken with a 33 cm space telescope (MSX). Deconvolution of both the Spitzer and MSX data are also presented that reconstruct the image at resolution consistent with that expected from the 6.5 meter aperture James Webb Space Telescope. I will present results for varying degrees of background complexity and examine the limitations of the MCS method for use on infrared data in regions of high source density and bright, complex backgrounds.

  1. Electrical structure in two thunderstorm anvil clouds

    NASA Technical Reports Server (NTRS)

    Marshall, Thomas C.; Rust, W. David; Winn, William P.; Gilbert, Kenneth E.

    1989-01-01

    Electrical structures in two thunderstorm anvil clouds (or 'anvils'), one in New Mexico, the other in Oklahoma, were investigated, using measurements of electric field by balloon-carried instruments and a one-dimensional model to calculate the time and spatial variations of electrical parameters in the clear air below the anvil. The electric field soundings through the two thunderstorm anvils showed similar charge structures; namely, negatively charged screening layers on the top and the bottom surfaces, a layer of positive charge in the interior, and one or two layers of zero charge. It is suggested that the positive charge originated in the main positive charge region normally found at high altitudes in the core of thunderclouds, and the negatively charged layers probably formed as screening layers, resulting from the discontinuity in the electrical conductivity at the cloud boundaries.

  2. 16 CFR Figures 11, 12 and 13 to... - Hemispherical Anvil and Curbstone Anvil

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Hemispherical Anvil and Curbstone Anvil 11, Figures 11, 12 and 13 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Figs. 11, 12, 13 Figures...

  3. 16 CFR Figures 11, 12 and 13 to... - Hemispherical Anvil and Curbstone Anvil

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Hemispherical Anvil and Curbstone Anvil 11, Figures 11, 12 and 13 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Figs. 11, 12, 13 Figures...

  4. 16 CFR Figures 11, 12 and 13 to... - Hemispherical Anvil and Curbstone Anvil

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Hemispherical Anvil and Curbstone Anvil 11, Figures 11, 12 and 13 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Figs. 11, 12, 13 Figures...

  5. 16 CFR Figures 11, 12 and 13 to... - Hemispherical Anvil and Curbstone Anvil

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Hemispherical Anvil and Curbstone Anvil 11, Figures 11, 12 and 13 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Figs. 11, 12, 13 Figures...

  6. 16 CFR Figures 11, 12 and 13 to... - Hemispherical Anvil and Curbstone Anvil

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Hemispherical Anvil and Curbstone Anvil 11, Figures 11, 12 and 13 to Part 1203 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION CONSUMER PRODUCT SAFETY ACT REGULATIONS SAFETY STANDARD FOR BICYCLE HELMETS Pt. 1203, Figs. 11, 12, 13 Figures...

  7. Thermodynamic control of anvil cloud amount

    NASA Astrophysics Data System (ADS)

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko; Medeiros, Brian

    2016-08-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation.

  8. Combining Research Approaches: The Anvil Writers Revisited.

    ERIC Educational Resources Information Center

    Sanders, Keith P.; Morris, Daniel N.

    1990-01-01

    Conjoins Q methodology with the interviewing techniques of the oral historian in a study of eight surviving contributors to "The Anvil," a midwestern proletarian magazine of the 1920s and 1930s. Finds four factors, labeled as the patron, the revolutionary artist, the Jack Conroy factor, and the humanist. Discusses the limitations and advantages of…

  9. 21 CFR 882.4030 - Skull plate anvil.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Skull plate anvil. 882.4030 Section 882.4030 Food... DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4030 Skull plate anvil. (a) Identification. A skull plate anvil is a device used to form alterable skull plates in the proper shape to...

  10. 21 CFR 882.4030 - Skull plate anvil.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Skull plate anvil. 882.4030 Section 882.4030 Food... DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4030 Skull plate anvil. (a) Identification. A skull plate anvil is a device used to form alterable skull plates in the proper shape to...

  11. 21 CFR 882.4030 - Skull plate anvil.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Skull plate anvil. 882.4030 Section 882.4030 Food... DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4030 Skull plate anvil. (a) Identification. A skull plate anvil is a device used to form alterable skull plates in the proper shape to...

  12. 21 CFR 882.4030 - Skull plate anvil.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Skull plate anvil. 882.4030 Section 882.4030 Food... DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4030 Skull plate anvil. (a) Identification. A skull plate anvil is a device used to form alterable skull plates in the proper shape to...

  13. 21 CFR 882.4030 - Skull plate anvil.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Skull plate anvil. 882.4030 Section 882.4030 Food... DEVICES NEUROLOGICAL DEVICES Neurological Surgical Devices § 882.4030 Skull plate anvil. (a) Identification. A skull plate anvil is a device used to form alterable skull plates in the proper shape to...

  14. Deformation of ICMEs/MCs along their path

    NASA Astrophysics Data System (ADS)

    Lynnyk, A.; Šafránková, J.; Němeček, Z.; Richardson, J. D.

    2011-07-01

    Interplanetary coronal mass ejections (ICMEs) and their subset, magnetic clouds (MCs), are important manifestations of solar activity which have substantial impact on the geomagnetic field. We re-analyze events already identified in Wind and Voyager 2 data and estimate changes of their geometry along the path from the Sun. The analysis is based on the thickness of the sheath between a shock and a particular ICME or MC which is proportional to the apparent curvature radius of ICMEs/MCs. We have found that this apparent radius of curvature increases with the Mach number and this effect is attributed to the larger deformation of the fast ICME/MC. Further, the relative sheath thickness that is proportional to the flux rope oblateness decreases with the magnetic field intensity inside the ICME/MC and increases with the heliospheric distance.

  15. Fine tuning GPS clock estimation in the MCS

    NASA Technical Reports Server (NTRS)

    Hutsell, Steven T.

    1995-01-01

    With the completion of a 24 operational satellite constellation, GPS is fast approaching the critical milestone, Full Operational Capability (FOC). Although GPS is well capable of providing the timing accuracy and stability figures required by system specifications, the GPS community will continue to strive for further improvements in performance. The GPS Master Control Station (MCS) recently demonstrated that timing improvements are always composite Clock, and hence, Kalman Filter state estimation, providing a small improvement to user accuracy.

  16. MCS precipitation and downburst intensity response to increased aerosol concentrations

    NASA Astrophysics Data System (ADS)

    Clavner, M.; Cotton, W. R.; van den Heever, S. C.

    2015-12-01

    Mesoscale convective systems (MCSs) are important contributors to rainfall in the High Plains of the United States as well as producers of severe weather such as hail, tornados and straight-line wind events known as derechos. Past studies have shown that changes in aerosol concentrations serving as cloud condensation nuclei (CCN) alter the MCS hydrometeor characteristics which in turn modify precipitation yield, downdraft velocity, cold-pool strength, storm propagation and the potential for severe weather to occur. In this study, the sensitivity of MCS precipitation characteristics and convective downburst velocities associated with a derecho to changes in CCN concentrations were examined by simulating a case study using the Regional Atmospheric Modeling System (RAMS). The case study of the 8 May 2009 "Super-Derecho" MCS was chosen since it produced a swath of widespread wind damage in association with an embedded large-scale bow echo, over a broad region from the High Plains of western Kansas to the foothills of the Appalachians. The sensitivity of the storm to changes in CCN concentrations was examined by conducting a set of three simulations which differed in the initial aerosol concentration based on output from the 3D chemical transport model, GEOS-Chem. Results from this study indicate that while increasing CCN concentrations led to an increase in precipitation rates, the changes to the derecho strength were not linear. A moderate increase in aerosol concentration reduced the derecho strength, while the simulation with the highest aerosol concentrations increased the derecho intensity. These changes are attributed to the impact of enhanced CCN concentration on the production of convective downbursts. An analysis of aerosol loading impacts on these MCS features will be presented.

  17. Relating the Hadamard Variance to MCS Kalman Filter Clock Estimation

    NASA Technical Reports Server (NTRS)

    Hutsell, Steven T.

    1996-01-01

    The Global Positioning System (GPS) Master Control Station (MCS) currently makes significant use of the Allan Variance. This two-sample variance equation has proven excellent as a handy, understandable tool, both for time domain analysis of GPS cesium frequency standards, and for fine tuning the MCS's state estimation of these atomic clocks. The Allan Variance does not explicitly converge for the nose types of alpha less than or equal to minus 3 and can be greatly affected by frequency drift. Because GPS rubidium frequency standards exhibit non-trivial aging and aging noise characteristics, the basic Allan Variance analysis must be augmented in order to (a) compensate for a dynamic frequency drift, and (b) characterize two additional noise types, specifically alpha = minus 3, and alpha = minus 4. As the GPS program progresses, we will utilize a larger percentage of rubidium frequency standards than ever before. Hence, GPS rubidium clock characterization will require more attention than ever before. The three sample variance, commonly referred to as a renormalized Hadamard Variance, is unaffected by linear frequency drift, converges for alpha is greater than minus 5, and thus has utility for modeling noise in GPS rubidium frequency standards. This paper demonstrates the potential of Hadamard Variance analysis in GPS operations, and presents an equation that relates the Hadamard Variance to the MCS's Kalman filter process noises.

  18. Clinical consequences of the EI/MCS "diagnosis": two paths.

    PubMed

    Staudenmayer, H

    1996-08-01

    There are two distinct paths down which patients "diagnosed" with environmental illness/multiple chemical sensitivities (EI/MCS) can travel. Along the first path, beliefs about low-level, multiple chemical sensitivities as the cause of physical and psychological symptoms are instilled and reinforced by a host of factors including toxicogenic speculation, iatrogenic influence mediated by unsubstantiated diagnostic and treatment practices, patient support/advocacy networks, and social contagion. Intrapsychic factors also reinforce this path through the motivational mechanism of factitious malingering, or unconscious primary and secondary gain, mediated through psychological defenses, particularly projection of cause of illness onto the physical environment. The second path involves restructuring distorted beliefs about chemical sensitivities. Explanations of the placebo effect, the physiology of the stress response, and the symptoms of anxiety and panic facilitate the direction of EI/MCS patients onto this path. A decision model is presented to discriminate among toxicogenic and psychogenic explanations of the EI/MCS phenomenon, based on appraisal of reaction and physiologic and cognitive responses during provocation chamber challenges under double-blind, placebo-controlled conditions. These studies have been helpful therapeutically for some patients in selecting the path that leads to wellness. This paper suggests how various therapeutic techniques can be employed with difficult patients. Often, supportive psychotherapy establishes a therapeutic alliance which facilitates cognitive therapy to restructure distorted beliefs. In the process of finding alternative explanations to chemical sensitivities, the etiology of symptoms is related to stressful life events, including childhood experiences which may have disrupted normal personality development and coping capacity. Furthermore, biological and physiological sequelae stemming from early, chronic trauma have been

  19. Thermodynamic control of anvil cloud amount.

    PubMed

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A; Voigt, Aiko; Medeiros, Brian

    2016-08-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative-convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation. PMID:27412863

  20. Thermodynamic control of anvil cloud amount

    PubMed Central

    Bony, Sandrine; Stevens, Bjorn; Coppin, David; Becker, Tobias; Reed, Kevin A.; Voigt, Aiko

    2016-01-01

    General circulation models show that as the surface temperature increases, the convective anvil clouds shrink. By analyzing radiative–convective equilibrium simulations, we show that this behavior is rooted in basic energetic and thermodynamic properties of the atmosphere: As the climate warms, the clouds rise and remain at nearly the same temperature, but find themselves in a more stable atmosphere; this enhanced stability reduces the convective outflow in the upper troposphere and decreases the anvil cloud fraction. By warming the troposphere and increasing the upper-tropospheric stability, the clustering of deep convection also reduces the convective outflow and the anvil cloud fraction. When clouds are radiatively active, this robust coupling between temperature, high clouds, and circulation exerts a positive feedback on convective aggregation and favors the maintenance of strongly aggregated atmospheric states at high temperatures. This stability iris mechanism likely contributes to the narrowing of rainy areas as the climate warms. Whether or not it influences climate sensitivity requires further investigation. PMID:27412863

  1. Anvil microphysical signatures associated with lightning-produced NOx

    NASA Astrophysics Data System (ADS)

    Stith, J. L.; Basarab, B.; Rutledge, S. A.; Weinheimer, A.

    2015-11-01

    Thunderstorm anvils were studied during the Deep Convective Clouds and Chemistry experiment (DC3), using in situ measurements and observations of ice particles and NOx together with radar and lightning mapping array measurements. A characteristic ice particle and NOx signature was found in the anvils from three storms, each containing high lightning flash rates in the storm core prior to anvil sampling. This signature exhibits high concentrations of frozen droplets (as measured by a Cloud Droplet Probe) coincident with lower NOx on the edges of the anvil. The central portion of these anvils exhibited a high degree of aggregation of these frozen droplets and higher levels of NOx. In contrast, a deep convective cell with low lightning flash rates had high concentrations of frozen droplets in its anvil's central region. A conceptual model for these results is presented. The abundance of frozen drop (chain) aggregates vs. individual frozen droplets in the central anvil region of the strong thunderstorms that were studied appears to be related to the degree of electrification (marked by increased lightning flash rates). Accordingly, the highest NOx concentrations coexist with regions where the most aggregation of frozen droplets has occurred. These observations between anvil microphysics and lightning/NOx signatures suggest that lightning data may be an important tool to characterize or infer the microphysical, radiative and chemical properties of thunderstorm anvils.

  2. Mineral Dust Impacts on Organized Convection Anvils

    NASA Astrophysics Data System (ADS)

    Seigel, R. B.; van den Heever, S. C.; Saleeby, S.

    2012-12-01

    Mineral dust in the atmosphere impacts both radiative and microphysical processes. As it is arguably the most abundant aerosol species in the world, dust plays a large role in the global energy budget. In order to understand its global distribution through transport, we must first understand how deep convective clouds microphysically process and subsequently vent mineral dust. This research utilizes a numerically simulated idealized squall line to (1) investigate the impact of mineral dust on convective anvils and aerosol venting, and (2) assess the aerosol indirect effect. To accomplish these tasks, we use the Regional Atmospheric Modeling System (RAMS) set up as a convection-resolving model (CRM). The CRM contains aerosol and microphysical schemes that allow radiatively active mineral dust particles to nucleate as cloud drops and ice crystals, replenish upon evaporation and sublimation, be tracked throughout hydrometeor transition, and scavenge by precipitation and dry sedimentation. Four simulations of the squall line are performed in order to directly assess the individual contributions of radiation and microphysics to the aerosol indirect effects from mineral dust. After three hours into the simulation of a squall line, the four sensitivity simulations are performed by toggling: (1) radiation off and dust not microphysically active; (2) radiation on and dust not microphysically active; (3) radiation off and dust microphysically active; and (4) radiation on and dust microphysically active. The systematic toggling between radiation on and dust being microphysically active allows for direct quantification of mineral dust impacts on various convective and radiative processes governing the squall line. As expansive organized convection anvils are greatly important for both regional and global radiation budgets, this research will highlight both mineral dusts impacts on the anvil region and the venting process of dust in the wake of deep convection.

  3. An improved hydrothermal diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Li, Jiankang; Bassett, W. A.; Chou, I.-Ming; Ding, Xin; Li, Shenghu; Wang, Xinyan

    2016-05-01

    A new type of HDAC-V hydrothermal diamond anvil cell (HDAC-VT) has been designed to meet the demands of X-ray research including X-Ray Fluorescence, X-ray Absorption Spectroscopy, and small angle X-ray scattering. The earlier version of HDAC-V that offered a large rectangular solid angle used two posts and two driver screws on both sides of a rectangular body. The new version HDAC-VT in a triangular shape has two alternative guide systems, either three posts inserted into bushings suitable for small anvil faces or linear ball bearings suitable for large anvil faces. The HDAC-VT having three driver screws offers the advantage of greater control and stability even though it sacrifices some of the size of solid angle. The greater control allows better sealing of samples, while greater stability results in longer survival for anvils and ceramic parts. This improved design retains several beneficial features of the original HDAC-V as well. These include the small collar that surrounds the heater and sample chamber forming an Ar + H2 gas chamber to protect diamonds and their heating parts from being oxidized. Three linear ball bearings, when used, fit to the three posts prevent seizing that can result from deterioration of lubricant at high temperatures. Positioning the posts and bearings outside of the gas chamber as in HDAC-V also prevents seizing and possible deformation due to overheating. In order to control the heating rate precisely with computer software, we use Linkam T95 and have replaced the Linkam 1400XY heating stage with the HDAC-VT allowing the HDAC to be heated to 950 °C at a rate from 0.01 °C/min to 50 °C/min. We have used the HDAC-VT and Linkam T95 to observe in situ nucleation and growth of zabuyelite in aqueous fluid and to homogenize melt inclusions in quartz from three porphyry deposits in Shanxi, China.

  4. An improved hydrothermal diamond anvil cell.

    PubMed

    Li, Jiankang; Bassett, W A; Chou, I-Ming; Ding, Xin; Li, Shenghu; Wang, Xinyan

    2016-05-01

    A new type of HDAC-V hydrothermal diamond anvil cell (HDAC-VT) has been designed to meet the demands of X-ray research including X-Ray Fluorescence, X-ray Absorption Spectroscopy, and small angle X-ray scattering. The earlier version of HDAC-V that offered a large rectangular solid angle used two posts and two driver screws on both sides of a rectangular body. The new version HDAC-VT in a triangular shape has two alternative guide systems, either three posts inserted into bushings suitable for small anvil faces or linear ball bearings suitable for large anvil faces. The HDAC-VT having three driver screws offers the advantage of greater control and stability even though it sacrifices some of the size of solid angle. The greater control allows better sealing of samples, while greater stability results in longer survival for anvils and ceramic parts. This improved design retains several beneficial features of the original HDAC-V as well. These include the small collar that surrounds the heater and sample chamber forming an Ar + H2 gas chamber to protect diamonds and their heating parts from being oxidized. Three linear ball bearings, when used, fit to the three posts prevent seizing that can result from deterioration of lubricant at high temperatures. Positioning the posts and bearings outside of the gas chamber as in HDAC-V also prevents seizing and possible deformation due to overheating. In order to control the heating rate precisely with computer software, we use Linkam T95 and have replaced the Linkam 1400XY heating stage with the HDAC-VT allowing the HDAC to be heated to 950 °C at a rate from 0.01 °C/min to 50 °C/min. We have used the HDAC-VT and Linkam T95 to observe in situ nucleation and growth of zabuyelite in aqueous fluid and to homogenize melt inclusions in quartz from three porphyry deposits in Shanxi, China. PMID:27250393

  5. Anvil microphysical signatures associated with lightning-produced NOx

    NASA Astrophysics Data System (ADS)

    Stith, Jeffrey L.; Basarab, Brett; Rutledge, Steven A.; Weinheimer, Andrew

    2016-02-01

    Thunderstorm anvils were studied during the Deep Convective Clouds and Chemistry experiment (DC3), using in situ measurements and observations of ice particles and NOx together with radar and Lightning Mapping Array measurements. A characteristic ice particle and NOx signature was found in the anvils from three storms, each containing high lightning flash rates in the storm core prior to anvil sampling. This signature exhibits high concentrations of frozen droplets (as measured by a Cloud Droplet Probe) coincident with lower NOx on the edges of the anvil. The central portion of these anvils exhibited a high degree of aggregation of these frozen droplets and higher levels of NOx. In contrast, a deep convective cell with low lightning flash rates had high concentrations of both frozen droplets and aggregated frozen droplets in its anvil's central region. A conceptual model for these results is presented and applied to the observations from each of these storms. High NOx concentrations are often found where aggregation of frozen droplets has occurred, which may be a reflection of aggregation by electrical forces in the regions where lightning is occurring, although the level of NOx for a given concentration of aggregates varies from storm to storm. These observations between anvil microphysics and lightning and/or NOx signatures suggest that lightning data may be an important tool to characterize or infer the microphysical, radiative, and chemical properties of thunderstorm anvils.

  6. Anvil Tool in the Advanced Weather Interactive Processing System

    NASA Technical Reports Server (NTRS)

    Barrett, Joe, III; Bauman, William, III; Keen, Jeremy

    2007-01-01

    Meteorologists from the 45th Weather Squadron (45 WS) and Spaceflight Meteorology Group (SMG) have identified anvil forecasting as one of their most challenging tasks when predicting the probability of violations of the lightning Launch Commit Criteria and Space Shuttle Flight Rules. As a result, the Applied Meteorology Unit (AMU) created a graphical overlay tool for the Meteorological Interactive Data Display Systems (MIDDS) to indicate the threat of thunderstorm anvil clouds, using either observed or model forecast winds as input. In order for the Anvil Tool to remain available to the meteorologists, the AMU was tasked to transition the tool to the Advanced Weather interactive Processing System (AWIPS). This report describes the work done by the AMU to develop the Anvil Tool for AWIPS to create a graphical overlay depicting the threat from thunderstorm anvil clouds. The AWIPS Anvil Tool is based on the previously deployed AMU MIDDS Anvil Tool. SMG and 45 WS forecasters have used the MIDDS Anvil Tool during launch and landing operations. SMG's primary weather analysis and display system is now AWIPS and the 45 WS has plans to replace MIDDS with AWIPS. The Anvil Tool creates a graphic that users can overlay on satellite or radar imagery to depict the potential location of thunderstorm anvils one, two, and three hours into the future. The locations are based on an average of the upper-level observed or forecasted winds. The graphic includes 10 and 20 nm standoff circles centered at the location of interest, in addition to one-, two-, and three-hour arcs in the upwind direction. The arcs extend outward across a 30 degree sector width based on a previous AMU study which determined thunderstorm anvils move in a direction plus or minus 15 degrees of the upper-level (300- to 150-mb) wind direction. This report briefly describes the history of the MIDDS Anvil Tool and then explains how the initial development of the AWIPS Anvil Tool was carried out. After testing was

  7. Nowcasting Thunderstorm Anvil Clouds Over KSC/CCAFS

    NASA Technical Reports Server (NTRS)

    Short, David A.; Sardonia, James E.; Lambert, Winifred C.; Wheeler, Mark M.

    2004-01-01

    Electrified thunderstorm anvil clouds extend the threat of natural and triggered lightning to space launch and landing operations far beyond the immediate vicinity of thunderstorm cells. The deep convective updrafts of thunderstorms transport large amounts of water vapor, super-cooled water droplets and ice crystals into the upper troposphere, forming anvil clouds, which are then carried downstream by the prevailing winds in the anvil formation layer. Electrified anvil clouds have been observed over the space launch and landing facilities of Kennedy Space Center (KSC) and Cape Canaveral Air Force Station (CCAFS), emanating from thunderstorm activity more than 200 km distant. Space launch commit criteria and flight rules require launch and landing vehicles to avoid penetration of the non-transparent portion of anvil clouds. The life cycles of 167 anvil clouds over the Florida peninsula and its coastal waters were documented using GOES-8 visible imagery on 50 anvil case days during the months of May through July 2001. Anvil clouds were found to propagate at the speed and direction of upper-tropospheric winds in the layer from 300-to-l50 mb, approximately 9.4 km to 14 km, with an effective average transport lifetime of 2 hours and a standard deviation of approximately 30 minutes. The effective lifetime refers to the time required for the nontransparent leading edge of an anvil cloud to reach its maximum extent before beginning to dissipate. The propagation and lifetime information was incorporated into the design, construction and implementation of an objective short-range anvil forecast tool based on upper-air observations, for use on the Meteorological Interactive Data Display System within the Range Weather Operations facility of the 45th Weather Squadron at CCAFS and the Spaceflight Meteorology Group at Johnson Space Center.

  8. Multiple Diamond Anvil (MDA) apparatus using nano-polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Irifune, T.; Kunimoto, T.; Tange, Y.; Shinmei, T.; Isobe, F.; Kurio, A.; Funakoshi, K.

    2011-12-01

    Thanks to the great efforts by Dave Mao, Bill Bassett, Taro Takahashi, and their colleagues at the University of Rochester through 1960s-70s, diamond anvil cell (DAC) became a major tool to investigate the deep Earth after its invention by scientists at NBS in 1958. DAC can now cover almost the entire pressure and temperature regimes of the Earth's interior, which seems to have solved the longstanding debate on the crystal structure of iron under the P-T conditions of the Earth's inner core. In contrast, various types of static large-volume presses (LVP) have been invented, where tungsten carbide has conventionally been used as anvils. Kawai-type multianvil apparatus (MA), which utilize 6 first-stage harden steel and 8 tungsten carbide anvils, is the most successful LVP, and has been used for accurate measurements of phase transitions, physical properties, element partitioning, etc. at high pressure and temperature. However, pressures using tungsten carbide as the second-stage anvils have been limited to about 30 GPa due to significant plastic deformation of the anvils. Efforts have been made to expand this pressure limit by replacing tungsten carbide anvils with harder sintered diamond (SD) anvils over the last two decades, but the pressures available in KMA with SD anvils have still been limited to below 100 GPa. We succeeded to produce nano-polycrystalline diamond (NPD or HIME-Diamond) in 2003, which is known to have ultrahigh hardness, very high toughness and elastic stiffness, high transmittance of light, relatively low thermal conductivity. These properties are feasible for its use as anvils, and some preliminary experiments of application of NPD anvils to laser heated DAC have successfully made in the last few years. We are now able to synthesize NPD rods with about 1cm in both diameter and length using a newly constructed 6000-ton KMA at Geodynamics Research Center, Ehime University, and have just started to apply this new polycrystalline diamond as anvils

  9. Homoepitaxial Boron Doped Diamond Anvils as Heating Elements in a Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey; Samudrala, Gopi; Smith, Spencer; Tsoi, Georgiy; Vohra, Yogesh; Weir, Samuel

    2013-03-01

    Recent advances in designer-diamond technology have allowed for the use of electrically and thermally conducting homoepitaxially-grown layers of boron-doped diamond (grown at 1200 °C with a 2% mixture of CH4 in H, resulting in extremely high doping levels ~ 1020/cm3) to be used as heating elements in a diamond anvil cell (DAC). These diamonds allow for precise control of the temperature inside of the diamond anvil itself, particularly when coupled with a cryostat. Furthermore, the unmatched thermally conducting nature of diamond ensures that no significant lateral gradient in temperature occurs across the culet area. Since a thermocouple can easily be attached anywhere on the diamond surface, we can also measure diamond temperatures directly. With two such heaters, one can raise sample temperatures uniformly, or with any desired gradient along the pressure axis while preserving optical access. In our continuing set of benchmark experiments, we use two newly created matching heater anvils with 500 μm culets to analyze the various fluorescence emission lines of ruby microspheres, which show more complicated behavior than traditional ruby chips. We also report on the temperature dependence of the high-pressure Raman modes of paracetamol (C8H9NO2) up to 20 GPa.

  10. Factors influencing the parameterization of tropical anvils within GCMs

    SciTech Connect

    Bradley, M.M.; Chin, H.N.S.

    1994-03-01

    The overall goal of this project is to improve the representation of anvil clouds and their effects in general circulation models (GCMs). We have concentrated on an important portion of the overall goal; the evolution of cumulus-generated anvil clouds and their effects on the large-scale environment. Because of the large range of spatial and temporal scales involved, we have been using a multi-scale approach. For the early-time generation and development of the citrus anvil we are using a cloud-scale model with a horizontal resolution of 1-2 kilometers, while for the transport of anvils by the large-scale flow we are using a mesoscale model with a horizontal resolution of 10-40 kilometers. The eventual goal is to use the information obtained from these simulations, together with available observations to develop an improved cloud parameterization for use in GCMS. The cloud-scale simulation of a midlatitude squall line case and the mesoscale study of a tropical anvil using an anvil generator were presented at the last ARM science team meeting. This paper concentrates on the cloud-scale study of a tropical squall line. Results are compared with its midlatitude counterparts to further our understanding of the formation mechanism of anvil clouds and the sensitivity of radiation to their optical properties.

  11. Cdc2 and the Regulation of Mitosis: Six Interacting Mcs Genes

    PubMed Central

    Molz, L.; Booher, R.; Young, P.; Beach, D.

    1989-01-01

    A cdc2-3w weel-50 double mutant of fission yeast displays a temperature-sensitive lethal phenotype that is associated with gross abnormalities of chromosome segregation and has been termed mitotic catastrophe. In order to identify new genetic elements that might interact with the cdc2 protein kinase in the regulation of mitosis, we have isolated revertants of the lethal double mutant. The suppressor mutations define six mcs genes (mcs: mitotic catastrophe suppressor) that are not allelic to any of the following mitotic control genes: cdc2, wee1, cdc13, cdc25, suc1 or nim1. Each mcs mutation is recessive with respect to wild-type in its ability to suppress mitotic catastrophe. None confer a lethal phenotype as a single mutant but few of the mutants are expected to be nulls. A diverse range of genetic interactions between the mcs mutants and other mitotic regulators were uncovered, including the following examples. First, mcs2 cdc2w or mcs6 cdc2w double mutants display a cell cycle defect dependent on the specific wee allele of cdc2. Second, both mcs1 cdc25-22 or mcs4 cdc25-22 double mutants are nonconditionally lethal, even at a temperature normally permissive for cdc25-22. Finally, the characteristic suppression of the cdc25 phenotype by a loss-of-function wee1 mutation is reversed in a mcs3 mutant background. The mcs genes define new mitotic elements that might be activators or substrates of the cdc2 protein kinase. PMID:2474475

  12. 4. FORGE, ANVIL, PEDESTAL GRINDER, AND BELT DRIVES. NOTE WATERWHEEL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. FORGE, ANVIL, PEDESTAL GRINDER, AND BELT DRIVES. NOTE WATERWHEEL NEEDLE VALVE CASTING HANGING ON THE WALL ABOVE THE FORGE. VIEW TO NORTH. - Santa Ana River Hydroelectric System, SAR-1 Machine Shop, Redlands, San Bernardino County, CA

  13. 31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND DOORWAY INTO MAIN SHOP-LOOKING SOUTHWEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

  14. Multi-scale evolution of a derecho-producing MCS

    NASA Astrophysics Data System (ADS)

    Bernardet, Ligia Ribeiro

    1997-12-01

    In this dissertation we address one type of severe weather: strong straight-line winds. In particular, we focus on derechos, a type of wind storm caused by a convective system and characterized by its long duration and by the large area it covers. One interesting characteristic of these storms is that they develop at night, on the cold side of a thermal boundary. This region is not characterized by large convective instability. In fact, surface parcels are generally stable with respect to vertical displacements. To gain understanding of the physical processes involved in these storms, we focused on the case of a MCS that developed in eastern Colorado on 12-13 May, 1985. The system formed in the afternoon, was active until early morning, and caused strong winds during the night. A multi-scale full physics simulation of this case was performed using a non-hydrostatic mesoscale model. Four telescopically nested grids covering from the synoptic scale down to cloud scale circulations were used. A Lagrangian model was used to follow trajectories of parcels that took part in the updraft and in the downdraft, and balance of forces were computed along the trajectories. Our results show that the synoptic and mesoscale environment of the storm largely influences convective organization and cloud-scale circulations. During the day, when the boundary layer is well mixed, the source of air for the clouds is located within the boundary layer. At night, when the boundary layer becomes stable, the source of air shifts to the top of the boundary layer. It is composed of warm, moist air that is brought by the nocturnal low-level jet. The downdraft structure also changes from day to night. During the day, parcels acquire negative buoyancy because of cooling due to evaporation and melting. As they sink, they remain colder than the environment, and end up at the surface constituting the cold pool. During the night, downdrafts are stronger, generating the strong surface winds. The most

  15. Investigation on stress distribution of multilayered composite structure (MCS) using infrared thermographic technique

    NASA Astrophysics Data System (ADS)

    Liu, Junyan; Gong, Jinlong; Liu, Liqiang; Qin, Lei; Wang, Yang

    2013-11-01

    In this paper, the thermoelastic stress analysis (TSA) on a multilayered composite structure (MCS) was investigated by means of lock-in thermographic image technique (LITI). The application of thermoelastic stress analysis on MCS becomes particularly complicated due to consisting of different material components, which determines the different thermoelastic coupling response depended on material thermal-physical property. The thermoelastic coupling constants (TCC) of GFRP, medium-carbon steel and foam were obtained through thermomechanical calibration experiments, respectively. An artificial neural network was proposed to determine the component of MCS. Comparisons between finite element analysis (FEA) and LITI measurement are reported. It is found that the stress distribution of MCS can be evaluated with good accuracies using LITI measurement.

  16. Cloud resolving modelling of the life cycle of a MCS: Sensitivity to soil conditions over West Africa

    NASA Astrophysics Data System (ADS)

    Gantner, L.; Kalthoff, N.

    2009-09-01

    In the African Sahelian (12°N-18°N) and Sudanian climate zone (9°N-11°N) convective systems contribute about 80-90% and about 50%, respectively, to the annual rainfall. Thus, they play a key role in the water cycle of West Africa. Their rainfall, however, is highly variable in space as well as in time. The initiation and modification of rain-producing convective systems in West Africa are still not well understood. In addition to mid- and upper-tropospheric forcing, the influence of surface and convective boundary layer (CBL) processes on the initiation of convection is often emphasised. Major factors are the spatial distribution and temporal development of water vapour in the CBL. Besides advective processes, water vapour is made available in the atmosphere locally through evapotranspiration from soil and vegetation; the latter is an important component of the earth's surface energy balance. Soil moisture affects the energy balance via the albedo and emissivity of the surface, the conduction of heat in the soil and the stomata resistance of vegetation. Research findings show that the soil moisture exerts greater influence on the CBL than vegetation. Cloud resolving real-case simulations initialized with ECMWF analysis data were performed to investigate the sensitivity of a mesoscale convective system (MCS) to soil properties. Several scenarios with different content of soil moisture and distribution of soil conditions were investigated. Initiation of convection was observed in all experiments. The initiation area was characterised by very low convective inhibition (CIN) and high convective available potential energy. The simulations showed some evidence that convection was initiated in the vicinity of orography and along soil moisture inhomogeneities. In a moist case precipitating cells were weak and disappeared when entering a region with higher CIN. In the other experiments MCSs developed. In the control run a weakening of the system was observed when

  17. Analysis of in situ measurements of cirrus anvil outflow dynamics

    NASA Astrophysics Data System (ADS)

    Lederman, J. I.; Whiteway, J. A.

    2012-12-01

    The airborne campaign, EMERALD 2 (Egrett Microphysics Experiment with Radiation, Lidar, and Dynamics,) was conducted out of Darwin, Australia in 2002. Objectives included characterization of the dynamics in the cirrus anvil outflow from tropical deep convection. Two aircraft, the Egrett and King Air, were flown in tandem in the upper troposphere (7 km - 15 km) to collect in situ measurements in the anvil outflow from a storm named "Hector" that occurs on a regular basis over the Tiwi Islands north of Darwin during November and December. Turbulence probes mounted on the wings of the Egrett aircraft were used to measure the wind fluctuations across the anvil and along its length with a spatial resolution of 2 meters. The in situ measurements from the Egrett were coincident with lidar measurements of the cloud structure from the King Air aircraft flying directly below. The presentation will show results of the analysis of the measurements with an emphasis on the turbulence, gravity waves, and coherent structures that are particular to the cirrus anvil outflow environment. Emphasis is placed on the dynamics associated with the generation of mammatus formations at the base of the anvil clouds.

  18. Schizosaccharomyces pombe Mop1-Mcs2 is related to mammalian CAK.

    PubMed Central

    Damagnez, V; Mäkelä, T P; Cottarel, G

    1995-01-01

    The cyclin-dependent kinase (CDK)-activating kinase, CAK, from mammals and amphibians consists of MO15/CDK7 and cyclin H, a complex which has been identified also as a RNA polymerase II C-terminal domain (CTD) kinase. While the Schizosaccharomyces pombe cdc2 gene product also requires an activating phosphorylation, the enzyme responsible has not been identified. We have isolated an essential S.pombe gene, mop1, whose product is closely related to MO15 and to Saccharomyces cerevisiae Kin28. The functional similarity of Mop1 and MO15 is reflected in the ability of MO15 to rescue a mop1 null allele. This suggests that Mop1 would be a CDK, and indeed Mop1 associates with a previously characterized cyclin H-related cyclin Mcs2 of S.pombe. Also, Mop1 and Mcs2 can associate with the heterologous partners human cyclin H and MO15, respectively. Moreover, the rescue of a temperature-sensitive mcs2 strain by expression of mop1+ demonstrates a genetic interaction between mop1 and mcs2. In a functional assay, immunoprecipitated Mop1-Mcs2 acts both as an RNA polymerase II CTD kinase and as a CAK. The CAK activity of Mop1-Mcs2 distinguishes it from the related CDK-cyclin pair Kin28-Ccl1 from S.cerevisiae, and supports the notion that Mop1-Mcs2 may represent a homolog of MO15-cyclin H in S.pombe with apparent dual roles as a RNA polymerase CTD kinase and as a CAK. Images PMID:8557036

  19. Zen diamond-anvil low-pressure cell

    NASA Astrophysics Data System (ADS)

    van Uden, N. W. A.; Dunstan, D. J.

    2000-11-01

    A diamond-anvil cell can be operated with only one anvil in order to generate modest pressures in relatively large volumes. We demonstrate it to pressures up to 2.5 GPa with gaskets of steel, brass, and other metals, with a sample chamber 0.25 mm in diameter by 0.25-0.9 mm depth, and with various pressure media. In this form the cell is very simple to operate and is useful for much work on biological systems and soft solids which requires pressures in the 1 GPa range.

  20. Thermal Diffusivity and Conductivity Measurements in Diamond Anvil Cells

    SciTech Connect

    Antonangeli, D; Farber, D L

    2007-02-22

    We have undertaken a study of the feasibility of an innovative method for the determination of thermal properties of materials at extreme conditions. Our approach is essentiality an extension of the flash method to the geometry of the diamond-anvil cell and our ultimate goal is to greatly enlarge the pressure and temperature range over which thermal properties can be investigated. More specifically, we have performed test experiments to establish a technique for probing thermal diffusivity on samples of dimensions compatible with the physical constraints of the diamond anvil cell.

  1. Anvil Forecast Tool in the Advanced Weather Interactive Processing System

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III; Hood, Doris

    2009-01-01

    Meteorologists from the 45th Weather Squadron (45 WS) and National Weather Service Spaceflight Meteorology Group (SMG) have identified anvil forecasting as one of their most challenging tasks when predicting the probability of violations of the Lightning Launch Commit Criteria and Space Shuttle Flight Rules. As a result, the Applied Meteorology Unit (AMU) was tasked to create a graphical overlay tool for the Meteorological Interactive Data Display System (MIDDS) that indicates the threat of thunderstorm anvil clouds, using either observed or model forecast winds as input. The tool creates a graphic depicting the potential location of thunderstorm anvils one, two, and three hours into the future. The locations are based on the average of the upper level observed or forecasted winds. The graphic includes 10 and 20 n mi standoff circles centered at the location of interest, as well as one-, two-, and three-hour arcs in the upwind direction. The arcs extend outward across a 30 sector width based on a previous AMU study that determined thunderstorm anvils move in a direction plus or minus 15 of the upper-level wind direction. The AMU was then tasked to transition the tool to the Advanced Weather Interactive Processing System (AWIPS). SMG later requested the tool be updated to provide more flexibility and quicker access to model data. This presentation describes the work performed by the AMU to transition the tool into AWIPS, as well as the subsequent improvements made to the tool.

  2. How to detect melting in laser heating diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Liuxiang, Yang

    2016-07-01

    Research on the melting phenomenon is the most challenging work in the high pressure/temperature field. Until now, large discrepancies still exist in the melting curve of iron, the most interesting and extensively studied element in geoscience research. Here we present a summary about techniques detecting melting in the laser heating diamond anvil cell.

  3. Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu3+) as a drug carrier.

    PubMed

    Fan, Yong; Huang, Shanshan; Jiang, Jinhua; Li, Guogang; Yang, Piaoping; Lian, Hongzhou; Cheng, Ziyong; Lin, Jun

    2011-05-15

    Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu) was successfully synthesized. The obtained MCS: Eu(3+) was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as the model drug. The structural, morphological, textural, and optical properties were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption/desorption, and photoluminescence (PL) spectra, respectively. The results reveal that the MCS: Eu exhibits the typical ordered characteristics of the mesostructure. This composite shows a sustained release profile with IBU as the model drug. The IBU-loaded samples still present red luminescence of Eu(3+) ((5)D(0)-(7)F(1,2)) under UV irradiation. The emission intensities of Eu(3+) in the drug carrier system vary with the amount of released IBU, making the drug release easily tracked and monitored. The system demonstrates a great potential for drug delivery and disease therapy. PMID:21376337

  4. Sequence and batch language programs and alarm related C Programs for the 242-A MCS

    SciTech Connect

    Berger, J.F.

    1996-04-15

    A Distributive Process Control system was purchased by Project B-534, 242-A Evaporator/Crystallizer Upgrades. This control system, called the Monitor and Control system (MCS), was installed in the 242-A evaporator located in the 200 East Area. The purpose of the MCS is to monitor and control the Evaporator and monitor a number of alarms and other signals from various Tank Farm facilities. Applications software for the MCS was developed by the Waste Treatment Systems Engineering (WTSE) group of Westinghouse. The standard displays and alarm scheme provide for control and monitoring, but do not directly indicate the signal location or depict the overall process. To do this, WTSE developed a second alarm scheme.

  5. Pressure, stress, and strain distribution in the double-stage diamond anvil cell

    SciTech Connect

    Lobanov, Sergey S.; Prakapenka, Vitali B.; Prescher, Clemens; Konôpková, Zuzana; Liermann, Hanns-Peter; Crispin, Katherine L.; Zhang, Chi; Goncharov, Alexander F.

    2015-07-21

    Double stage diamond anvil cells (DACs) of two designs have been assembled and tested. We used a standard symmetric DAC with flat or beveled culets as a primary stage and CVD microanvils machined by a focused ion beam as a second. We evaluated pressure, stress, and strain distributions in gold and a mixture of gold and iron as well as in secondary anvils using synchrotron x-ray diffraction with a micro-focused beam. A maximum pressure of 240 GPa was reached independent of the first stage anvil culet size. We found that the stress field generated by the second stage anvils is typical of conventional DAC experiments. The maximum pressures reached are limited by strains developing in the secondary anvil and by cupping of the first stage diamond anvil in the presented experimental designs. Also, our experiments show that pressures of several megabars may be reached without sacrificing the first stage diamond anvils.

  6. Clinical characteristics of chemical sensitivity: an illustrative case history of asthma and MCS.

    PubMed

    Ross, G H

    1997-03-01

    A case history of the induction of asthma and chemical sensitivity in a 42-year-old registered nurse illustrates several of the characteristic features of multiple chemical sensitivity (MCS). This patient's problems started shortly after moving into a new home under construction, with associated chemical exposures. Other MCS patients report the onset of the condition with other chemical exposures such as those encountered at their places of work or use of pesticides at their residences. Patients often describe a spreading phenomenon of increasing intolerance to commonly encountered chemicals at concentrations well tolerated by other people. Symptoms usually wax and wane with exposures, and are more likely to occur in patients or families with preexisting histories of migraine or with classical allergies. Idiosyncratic medication reactions (especially to preservative chemicals) are common in MCS patients, as are dysautonomia symptoms (such as vascular instability) and poor temperature regulation. Myalgia and joint pains and food intolerance are common features as well. Contamination with xenobiotic chemicals is frequently found in these patients when they are tested. Reactive airways dysfunction syndrome is a recently identified condition that exhibits features of both asthma and chemical sensitivity. MCS patients frequently have patterns of neurotoxic brain metabolism that can be confirmed on single photo emission computed tomography imaging. PMID:9167976

  7. Clinical characteristics of chemical sensitivity: an illustrative case history of asthma and MCS.

    PubMed Central

    Ross, G H

    1997-01-01

    A case history of the induction of asthma and chemical sensitivity in a 42-year-old registered nurse illustrates several of the characteristic features of multiple chemical sensitivity (MCS). This patient's problems started shortly after moving into a new home under construction, with associated chemical exposures. Other MCS patients report the onset of the condition with other chemical exposures such as those encountered at their places of work or use of pesticides at their residences. Patients often describe a spreading phenomenon of increasing intolerance to commonly encountered chemicals at concentrations well tolerated by other people. Symptoms usually wax and wane with exposures, and are more likely to occur in patients or families with preexisting histories of migraine or with classical allergies. Idiosyncratic medication reactions (especially to preservative chemicals) are common in MCS patients, as are dysautonomia symptoms (such as vascular instability) and poor temperature regulation. Myalgia and joint pains and food intolerance are common features as well. Contamination with xenobiotic chemicals is frequently found in these patients when they are tested. Reactive airways dysfunction syndrome is a recently identified condition that exhibits features of both asthma and chemical sensitivity. MCS patients frequently have patterns of neurotoxic brain metabolism that can be confirmed on single photo emission computed tomography imaging. PMID:9167976

  8. Response of mesoscale convective system (MCS) and cold pool formation to dust-radiative effects

    NASA Astrophysics Data System (ADS)

    Waylonis, M. T.; Chen, S. H.

    2014-12-01

    This study examines the role of dust in the development of a mesoscale convective system (MCS) over the central-west Sahara, and how cold pools from the MCS feedback to dust emissions. Few studies have simulated the direct-radiative effects of dust on cloud development. Moderate Resolution Imaging Spectrometer (MODIS) and Multi-angle Imaging Spectrometer (MISR) Retrieved aerosol optical depth and Meteosat Second Generation dust enhancement product were used to examine a dust outbreak that occurred between 13 and 15 August 2005 and revealed that an moist intrusion into the Sahara caused a MCS to form and resulted in dust emission due to cold pool outflow from the MCS. A dust model based on the Weather Research and Forecasting model was developed to include dust emissions, transport, dry and moist deposition, and radiation interactions and was used to simulate the case. Dust-radiation interactions were found to enhance convective strength through low-level heating, which increased convective available potential energy and low-level convergence. The increased intensity of the convection led to stronger and more widespread cold pool formation, which in turn emitted more dust into the atmosphere.

  9. Electroplated mounting of diamond anvils for use in cryogenic systems

    NASA Astrophysics Data System (ADS)

    Pugh, E.; Haselwimmer, R. K. W.

    2006-08-01

    The mounting of diamonds using the electroplated deposition of copper was originally developed to hold diamonds in place during polishing. This article describes the extension and application of this method for the mounting of diamonds inside diamond anvil cells. The novel method described, unlike more traditional gluing or clamping methods, can withstand both continual thermal cycling and provide a small profile such that it can be used in miniature cells to permit ample space for fitting electrical feed throughs or external coils around the anvils. The method is developed such that it can be used to attach the diamond to nonmetallic backing plates such as sapphire. Details of precautions to reduce the production of eddy currents in the deposited copper when performing ac-susceptibility measurements are also described.

  10. CRYSTAL: The Cirrus Regional Study of Tropical Anvils and Layers

    NASA Technical Reports Server (NTRS)

    Delnore, Victor E.; Cox, Stephen K.; Curran, Robert J.

    1999-01-01

    CRYSTAL the Cirrus Regional Study of Tropical Anvils and Layers is part of the ongoing series of field experiments to study clouds and their impact on world weather and climate, and will attempt to improve the application of cloud effects in global climate models. CRYSTAL is being planned as two parts: a limited CRYSTAL field campaign in 2001 to examine towering clouds and anvil genesis over the Everglades of Florida, and the main CRYSTAL field campaign in the summer of 2003 in the Tropical Western Pacific. The latter is timed to take advantage of several cloud measurement satellites that will be operational at that time. This paper discusses some of the issues to be addressed in CRYSTAL, gives a brief description of the research plan, and describes its relationship to other important field experiments.

  11. DisoMCS: Accurately Predicting Protein Intrinsically Disordered Regions Using a Multi-Class Conservative Score Approach

    PubMed Central

    Wang, Zhiheng; Yang, Qianqian; Li, Tonghua; Cong, Peisheng

    2015-01-01

    The precise prediction of protein intrinsically disordered regions, which play a crucial role in biological procedures, is a necessary prerequisite to further the understanding of the principles and mechanisms of protein function. Here, we propose a novel predictor, DisoMCS, which is a more accurate predictor of protein intrinsically disordered regions. The DisoMCS bases on an original multi-class conservative score (MCS) obtained by sequence-order/disorder alignment. Initially, near-disorder regions are defined on fragments located at both the terminus of an ordered region connecting a disordered region. Then the multi-class conservative score is generated by sequence alignment against a known structure database and represented as order, near-disorder and disorder conservative scores. The MCS of each amino acid has three elements: order, near-disorder and disorder profiles. Finally, the MCS is exploited as features to identify disordered regions in sequences. DisoMCS utilizes a non-redundant data set as the training set, MCS and predicted secondary structure as features, and a conditional random field as the classification algorithm. In predicted near-disorder regions a residue is determined as an order or a disorder according to the optimized decision threshold. DisoMCS was evaluated by cross-validation, large-scale prediction, independent tests and CASP (Critical Assessment of Techniques for Protein Structure Prediction) tests. All results confirmed that DisoMCS was very competitive in terms of accuracy of prediction when compared with well-established publicly available disordered region predictors. It also indicated our approach was more accurate when a query has higher homologous with the knowledge database. Availability The DisoMCS is available at http://cal.tongji.edu.cn/disorder/. PMID:26090958

  12. Bridging the piston-cylinder/multi-anvil gap

    NASA Astrophysics Data System (ADS)

    Leinenweber, K.; Tyburczy, J. A.; Sharp, T. G.; Stoyanov, E.

    2007-12-01

    The piston-cylinder device is a favored tool for studying rocks under Earth's crust and uppermost mantle conditions. Experiments on fairly large sample volumes featuring careful control of pressure, temperature, oxygen fugacity, volatile content etc. are routine in this device, up to 3.0 GPa (non end-loaded) and 5.0 to 6.0 GPa (end-loaded). For higher-pressure studies, the multi-anvil takes the place of the piston-cylinder as the primary large-volume device. However, there is a notable gap in several capabilities when transitioning from the piston-cylinder to the multi-anvil. Because the furnace is necessarily shorter in a multi-anvil, thermal gradients are higher and the available volume is smaller. This makes it more difficult to control many environmental variables, such as oxygen fugacity, in a multi-anvil experiment. Much higher friction in the system means that pressure accuracy is lower. Also, it is more difficult to use quasi-hydrostatic media such as NaCl, which means that stresses and pressure gradients are likely to be higher. Current developments are aimed towards partially bridging this capability "gap" between piston-cylinders and multi-anvils. The development of new large-volume assemblies, through the COMPRES cell development project, will be described, in particular new larger octahedral assemblies with 18 and 25 mm edge lengths. A fundamental redesign of the furnace from the elongated furnaces characteristic of the piston-cylinder, which gain their low thermal gradients sinply from the length of the furnace (an infinite tubular furnace would have no thermal gradient inside) is necessary. While some laboratories have chosen step-heaters to reduce thermal gradients, we are experimenting with box heaters that are surrounded by a thermal insulating material (zirconia) and have very small electrical leads to avoid heat loss. The large sample volumes resulting from this design allow low- gradient experiments with sample volumes the same as those of a 3

  13. HYBRID BRIDGMAN ANVIL DESIGN: AN OPTICAL WINDOW FOR IN-SITU SPECTROSCOPY IN LARGE VOLUME PRESSES

    SciTech Connect

    Lipp, M J; Evans, W J; Yoo, C S

    2005-07-29

    The absence of in-situ optical probes for large volume presses often limits their application to high-pressure materials research. In this paper, we present a unique anvil/optical window-design for use in large volume presses, which consists of an inverted diamond anvil seated in a Bridgman type anvil. A small cylindrical aperture through the Bridgman anvil ending at the back of diamond anvil allows optical access to the sample chamber and permits direct optical spectroscopy measurements, such as ruby fluorescence (in-situ pressure) or Raman spectroscopy. This performance of this anvil-design has been demonstrated by loading KBr to a pressure of 14.5 GPa.

  14. Vertical Profiles of Aerosol Particle Sizes using MGS/TES and MRO/MCS

    NASA Astrophysics Data System (ADS)

    Wolff, M. J.; Clancy, R. T.; Smith, M. D.; Benson, J. L.; McConnochie, T. H.; Pankine, A.

    2012-12-01

    Vertical variations in aerosol particle sizes often have a dramatic impact on the state and evolution of the Martian atmosphere. Recent analyses of data from the Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars (SPICAM), the Thermal Emission Spectrometer (TES), and the Mars Climate Sounder (MCS) instruments offer some long overdue progress in constraining this aspect of aerosols. However, significantly more work remains to be done along these lines in order to better constrain and inform modern dynamical simulations of the Martian atmosphere. Thus, the primary goal of our work is to perform retrievals of particle size as a function of altitude for both dust and water ice aerosols. The choice of the TES and MCS dataset, with pole-to-pole coverage over a period of nearly eight martian years, provides the crucial systematic temporal and spatial sampling. Our presentation will include: 1) A summary of our limb radiative transfer algorithms and retrieval schemes; 2) The initial results of the application of our particle size retrieval scheme to the 2001 TES and 2007 MCS observations of those planet encircling dust events; 3) Near-term plans for for additional retrievals (aphelion cloud season, lower optical depth locations and seasons, etc.); 4) Location of the archive to be used for the distribution of the derived profiles and associated retrieval metadata.

  15. Comparison of Simulated and Observed Continental Tropical Anvil Clouds and Their Radiative Heating Profiles

    SciTech Connect

    Powell, Scott W.; Houze, R.; Kumar, Anil; McFarlane, Sally A.

    2012-09-06

    Vertically pointing millimeter-wavelength radar observations of anvil clouds extending from mesoscale convective systems (MCSs) that pass over an Atmospheric Radiation Measurement Program (ARM) field site in Niamey, Niger, are compared to anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model using six different microphysical schemes. The radar data provide the statistical distribution of the radar reflectivity values as a function of height and anvil thickness. These statistics are compared to the statistics of the modeled anvil cloud reflectivity at all altitudes. Requiring the model to be statistically accurate at all altitudes is a stringent test of the model performance. The typical vertical profile of radiative heating in the anvil clouds is computed from the radar observations. Variability of anvil structures from the different microphysical schemes provides an estimate of the inherent uncertainty in anvil radiative heating profiles. All schemes underestimate the optical thickness of thin anvils and cirrus, resulting in a bias of excessive net anvil heating in all of the simulations.

  16. Design and performance of tapered cubic anvil used for achieving higher pressure and larger sample cell.

    PubMed

    Han, Qi-Gang; Yang, Wen-Ke; Zhu, Pin-Wen; Ban, Qing-Chu; Yan, Ni; Zhang, Qiang

    2013-07-01

    In order to increase the maximum cell pressure of the cubic high pressure apparatus, we have developed a new structure of tungsten carbide cubic anvil (tapered cubic anvil), based on the principle of massive support and lateral support. Our results indicated that the tapered cubic anvil has some advantages. First, tapered cubic anvil can push the transfer rate of pressure well into the range above 36.37% compare to the conventional anvil. Second, the rate of failure crack decreases about 11.20% after the modification of the conventional anvil. Third, the limit of static high-pressure in the sample cell can be extended to 13 GPa, which can increase the maximum cell pressure about 73.3% than that of the conventional anvil. Fourth, the volume of sample cell compressed by tapered cubic anvils can be achieved to 14.13 mm(3) (3 mm diameter × 2 mm long), which is three and six orders of magnitude larger than that of double-stage apparatus and diamond anvil cell, respectively. This work represents a relatively simple method for achieving higher pressures and larger sample cell. PMID:23902079

  17. Raman Shift of Stressed Diamond Anvils: Pressure Calibration and Culet Geometry Dependence

    SciTech Connect

    Baer, B J; Chang, M E; Evans, W J

    2008-04-03

    The pressure dependence of the Raman shift of diamond for highly stressed anvils at the diamond-anvil sample interface has been measured for different culet shapes up to 180 GPa at ambient temperature. By using hydrogen samples, which constitute both a quasi-hydrostatic medium and a sensitive pressure sensor, some of the effects of culet and tip size have been determined. We propose that the divergent results in the literature can be partly ascribed to different anvil geometries. Experiments show increasing second order dependence of the diamond Raman shift with pressure for decreasing tip size. This is an important consideration when using the diamond anvils as a pressure sensor.

  18. Stone anvil damage by wild bearded capuchins (Sapajus libidinosus) during pounding tool use: a field experiment.

    PubMed

    Haslam, Michael; Cardoso, Raphael Moura; Visalberghi, Elisabetta; Fragaszy, Dorothy

    2014-01-01

    We recorded the damage that wild bearded capuchin monkeys (Sapajus libidinosus) caused to a sandstone anvil during pounding stone tool use, in an experimental setting. The anvil was undamaged when set up at the Fazenda Boa Vista (FBV) field laboratory in Piauí, Brazil, and subsequently the monkeys indirectly created a series of pits and destroyed the anvil surface by cracking palm nuts on it. We measured the size and rate of pit formation, and recorded when adult and immature monkeys removed loose material from the anvil surface. We found that new pits were formed with approximately every 10 nuts cracked, (corresponding to an average of 38 strikes with a stone tool), and that adult males were the primary initiators of new pit positions on the anvil. Whole nuts were preferentially placed within pits for cracking, and partially-broken nuts outside the established pits. Visible anvil damage was rapid, occurring within a day of the anvil's introduction to the field laboratory. Destruction of the anvil through use has continued for three years since the experiment, resulting in both a pitted surface and a surrounding archaeological debris field that replicate features seen at natural FBV anvils. PMID:25372879

  19. High pressure Moessbauer spectroscopy in diamond anvil cells

    SciTech Connect

    Taylor, R.D. ); Pasternak, M.P. . School of Physics and Astronomy Los Alamos National Lab., NM )

    1991-01-01

    Diamond anvil cells provide a means to obtain near-hydrostatic pressures from the kilobar to the megabar regime. Moessbauer spectroscopy (MS) nicely complements the optical and X-ray measurements usually made. After a brief summary of the techniques applicable to MS, we present several examples of high pressure MS including hysteresis in the {sub {alpha}}-{sub {var epsilon}} transition in Fe, metallization in molecular crystals and the insulator-metal Mott transition in NiI{sub 2} and CoI{sub 2}. 25 refs., 7 figs.

  20. Understanding subtropical anvil cirrus: A coupled modeling study

    NASA Astrophysics Data System (ADS)

    Carver, Robert Wyatt

    This research investigates the sensitivity of anvil layer cirrus's characteristics to its mesoscale environment. A coupled modeling system composed of a mesoscale model and cloud model is used to represent the evolution of systems with different scales. Lagrangian trajectories in the mesoscale model are used to determine the mesoscale environment of the simulated anvil and calculate the mesoscale forcing. A new sedimentation parameterization for the cloud model is developed to better represent fall speeds for large particles. Convection and the resulting outflow cirrus occurring near Ft. Myers, Florida on July 16, 2002 are used for the case study. The mesoscale model produced convection and an ice cloud similar to what was observed that day. The cloud model was used to determine the set of cloud processes in response to the mesoscale forcing that produced more condensate and prolonged cloud lifetime. These simulations show that differential radiative heating and cooling is the key process. The cooling and moistening in response to the mesoscale forcing produces more ice, enhancing cloud-top radiative cooling and cloud-base infrared warming. This generates more buoyancy, strengthening the cloud's updrafts and producing many small crystals to further enhance the cloud-top cooling, until sedimentation removes enough mass to end the positive feedbacks. The presence and magnitude of the mesoscale forcing alters the amount of condensate formed, altering the cloud-top cooling rate and the cloud's response to the forcing. The anvil cloud simulation was relatively insensitive to the initial condensate once the cloud becomes optically thick enough to be considered a black-body. While longwave cloud-top cooling is necessary for the interactions between mesoscale forcing and cloud dynamics, the most turbulent anvil cirrus layers require shortwave in-cloud warming. In response to recent measurements of the deposition coefficient, alpha d, I develop a parameterization that

  1. Miniature cryogenic diamond-anvil high-pressure cell

    NASA Astrophysics Data System (ADS)

    Dunstan, D. J.; Scherrer, W.

    1988-04-01

    A novel diamond-anvil cell is described which measures 19-mm diameter by 28 mm long to fit the Oxford Instruments CF 1204 flow cryostat, while providing full axial and tilt adjustment of the diamonds. The drive mechanism provides for pressure changes while the cell is in the cryostat. The small dimensions are achieved because the drive force is not transmitted through the tilt mechanism, and by the Bowden cable technique used for the drive mechanism. This cell makes high pressure a readily portable technique that can be brought to many already existing experimental apparatuses.

  2. Effective Ice Particle Densities for Cold Anvil Cirrus

    NASA Technical Reports Server (NTRS)

    Heymsfield, Andrew J.; Schmitt, Carl G.; Bansemer, Aaron; Baumgardner, Darrel; Weinstock, Elliot M.; Smith, Jessica

    2002-01-01

    This study derives effective ice particle densities from data collected from the NASA WB-57F aircraft near the tops of anvils during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers (CRYSTAL) Florida Area Cirrus Experiment (FACE) in southern Florida in July 2002. The effective density, defined as the ice particle mass divided by the volume of an equivalent diameter liquid sphere, is obtained for particle populations and single sizes containing mixed particle habits using measurements of condensed water content and particle size distributions. The mean effective densities for populations decrease with increasing slopes of the gamma size distributions fitted to the size distributions. The population-mean densities range from near 0.91 g/cu m to 0.15 g/cu m. Effective densities for single sizes obey a power-law with an exponent of about -0.55, somewhat less steep than found from earlier studies. Our interpretations apply to samples where particle sizes are generally below 200-300 microns in maximum dimension because of probe limitations.

  3. Radiative sensitivities of tropical anvils to small ice crystals

    NASA Astrophysics Data System (ADS)

    Zender, Charles S.; Kiehl, J. T.

    1994-12-01

    Stratiform anvils in the upper tropical troposphere were simulated to determine the sensitivities of their radiative properties to the presence of small ice crystals. Cloud evolution was modeled in a one-dimensional (vertical) framework incorporating an updraft, deposition, sublimation, sedimentation, nucleation, and radiation. The sensitivities of cloud radiative forcing, albedo, emissivity, and heating rate were derived from a test that included and then excluded the presence of numerous small crystals. These crystals sizes (3 < L < 20 μm) have been measured in recent observations but are smaller than the detection limit of most past observations. The shortwave forcing and albedo were very sensitive to the presence of the small crystals, even though these crystals accounted for less than 2% of total cloud mass. For optically thick anvils the longwave forcing and emissivity were, in general, much less sensitive to the small ice crystals than their shortwave counterparts. Radiative treatments assuming a hexagonal crystal habit yielded the same sensitivities as the spherical habit. The results agreed with previous studies in that the increased backscatter from hexagonal crystals enhanced the planetary albedo by ˜10-15%. The heating rate sensitivity to the small crystals depended on vertical location within the cloud and showed cancelation between the longwave and the shortwave heating perturbations. The small crystals changed heating rates by up to 50% at cloud top and base.

  4. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    DOE PAGESBeta

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage ofmore » 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.« less

  5. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    SciTech Connect

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage of 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.

  6. How Public Relations Practitioners Measure Success: A Critical Analysis of Silver Anvil Winners.

    ERIC Educational Resources Information Center

    Bissland, James H.

    A study examined the evaluation methods used in 58 top public relation projects, specifically the Silver Anvil winners of 1984 and 1985, to discover how well public relations practitioners are measuring and reporting success. Results indicated that measures of communication effect were most likely to be employed by Silver Anvil winners, measures…

  7. A Look at Dust Storms on Mars (2007 To 2009) Using MCS and THEMIS Observations

    NASA Astrophysics Data System (ADS)

    Flynn, William; Bowles, N. E.; Teanby, N. A.; Montabone, L.; Calcutt, S. B.; Read, P. L.; Kass, D. M.; Hale, A. S.

    2009-09-01

    Martian dust storms may be small, localised and short lived or can be large and intense and expand to enshroud most, if not all, of the planet within a few days. The martian dusty season occurs near the time of perihelion (closest approach to the sun) during Mars' southern hemisphere spring and summer. During this period (+/- 90 degrees Ls of perihelion) local and regional dust storms are more frequent and there is a higher probability of a major and possible planet-encircling dust storm occuring. Despite this there is still a lot of interannual variability and uncertainty regarding the occurence of both major and regional dust storms. The Mars Climate Sounder (MCS) instrument onboard NASA's Mars Reconnaissance Orbiter (MRO) is a two telescope 9 channel filter IR radiometer (0.3 to 45 microns), with each channel consisting of a linear array of 21 detectors. Each pixel sounds a 5km thick region of the Martian atmosphere in a limb viewing/scanning mode. We present a comparison of dust storm activity on Mars for 2007 to 2009 using MCS limb observations of changes in dust opacity. These measurements are also compared with observations and atmospheric opacity maps generated by the Thermal Emission Imaging System (THEMIS) multi-wavelength instrument onboard the Mars Odyssey spacecraft and Mars weather maps from MRO's Mars Color Imager (MARCI) for this period. Model predictions from the Mars Climate Database and simulations from the UK Mars General Circulation Model (GCM) are also used. This comparison gives us an empirical method for using MCS data directly to identify dust storm activity during this period.

  8. Cascade filtration (CF) with the Haemonetics MCS+: a new technical adaptation.

    PubMed

    Valbonesi, M; Bo, A; De Luigi, M C; Bruni, R; Stura, P; Sanfilippo, B; Varinelli, I

    2001-03-01

    CF was introduced in clinical medicine in 1980. Up to now, exclusively two-vein procedures have been carried out with some limitations to expansion of this technique. In this report we describe the very first application of single-needle CF carried out with Haemonetics MCS + apparatus. Twenty procedures were completed without any untoward effect in patients suffering from TTP, post-hepatitic cryoblobulinemia, familial hypercholesterolemia and acute Guillan-Barrè Syndrome. From 1 to 4 sessions were carried out per patient with the expected laboratory and clinical results. The only limit is the procedure time that averages 231 +/- 48 min., approximately 40% longer than two needle procedures. PMID:11314811

  9. In Situ Measurements of Microphysical and Radiative Properties of Cirrus and Anvil Clouds

    NASA Astrophysics Data System (ADS)

    Lawson, P.; Baker, B.; Pilson, B.

    2003-12-01

    In situ microphysical and radiative properties of mid-latitude cirrus, anvil and tropical anvil clouds, based on research flights conducted with the SPEC Learjet, the NASA WB-57 and DC-8, and the University of North Dakota Citation research aircraft, are presented. The measurements were collected in Colorado, Utah, Oklahoma, Florida and Kwajalein. All of the research aircraft were equipped with a standard complement of microphysical sensors and optical probes, plus a cloud particle imager (CPI), which produces high-definition (2.3 micron pixel) digital images of ice particles. The CPI data provide improved measurements of particle shape and size, facilitating better calculations of radiative properties of cirrus and anvil clouds. Based on the measurements, average mid-latitude cirrus, and mid-latitude and tropical cirrus microphysical properties of particle size distribution, crystal habit, ice water content, extinction coefficient, effective radius and optical depth are derived. The data show a distinct difference between particle characteristics in mid-latitude cirrus and anvil clouds. In cirrus, the predominate crystal type (weighted by area or mass) is the bullet rosette, a polycrystalline structure typical of crystal formation at temperatures colder than -30 C. Conversely, although anvils occur at temperatures similar to cirrus, bullet rosettes are very rare in anvils. Instead crystal types in anvils are typical of those formed at temperatures warmer than - 30 C. There is also a notable difference in microphysical and radiative characteristics between mid-latitude, Florida, and tropical (Kwajalein) anvils. Tropical anvils are comprised mainly of single crystals, mostly irregular blocky-shapes. In mid-latitude and Florida anvils, there are more aggregates and often chains of small particles that may be formed as a result of the higher electric fields in continental clouds. The impact of crystal type on calculations of radiative transfer are also considered.

  10. Effectiveness of the haemonetics MCS cell separator in the collection of apheresis platelets.

    PubMed

    Keklik, Muzaffer; Keklik, Ertugrul; Korkmaz, Serdal; Aygun, Bilal; Arik, Ferhat; Kilic, Ozcan; Sarikoc, Murat

    2015-12-01

    Platelet (PLT) transfusions play an important role in patients with thrombocytopenia or severely impaired platelet function. Platelet concentrates are prepared from whole-blood donations or by plateletpheresis. In recent years, different instruments have been developed to perform plateletpheresis. We evaluated an apheresis instrument, the Haemonetics MCS(®) + with regard to PLT yield, collection efficiency (CE), and collection rate (CR) in a retrospective, randomized study in 526 donors. In this system, we used leukoreduction filters post collection to obtain leukoreduced products. The Haemonetics MCS(®) + cell separator efficiently collected apheresis platelets with median PLT yields of 3.7 × 10(11), mean CE of 66.69 ± 13.73% and mean CR of 0.063 ± 0.013 × 10(11)/min. The median blood volume processed was 3290 (2420-4370) ml, and the median volume of acid citrate dextrose-A (ACD-A) used in collections on the device was 385 (196-517) ml. Also, this device allowed the collection of white blood cell (WBC) reduced plateletpheresis with mean 0.07 ± 0.15 × 10(6) WBC content. No serious donor or recipient reactions occurred. PMID:26283175

  11. Multi-Anvil, High-Pressure Apparatus: A Half Century of Development and Progress

    NASA Astrophysics Data System (ADS)

    Liebermann, R. C.

    2011-12-01

    It has been a little more than a half-century since H. Tracy Hall published his 1958 paper on the first multi-anvil, high-pressure apparatus, a tetrahedral-anvil device capable of attaining simultaneous pressures of 10 GPa and temperatures of 3000°C. Since that time, such multi-anvil apparatus have evolved progressively and can now reach pressures close to 100 GPa at high temperatures. Some multi-anvil apparatus have been utilized in conjunction with in situ X-ray diffraction, especially with the advent of synchrotron radiation facilities in the early 1980s. For the past 50+ years, there have been a variety of technological approaches to generating high pressures in the laboratory, primarily motivated by the desire to study the behavior of materials at elevated pressures and temperatures; many of these approaches have been developed in the Earth science community due to the desire to replicate in the laboratory the P-T conditions of the Earth's deep interior. In addition to the dynamic techniques of shock-wave experiments, there have been two complimentary static techniques to achieve these goals: the diamond-anvil cell and the multi-anvil apparatus. Although these two static techniques have occasionally been viewed as competitive, they are both useful and very complimentary. The purpose of this paper is to review the development and progress in multi-anvil apparatus.

  12. A new type of anvil in the Acheulian of Gesher Benot Ya'aqov, Israel.

    PubMed

    Goren-Inbar, Naama; Sharon, Gonen; Alperson-Afil, Nira; Herzlinger, Gadi

    2015-11-19

    We report here on the identification and characterization of thin basalt anvils, a newly discovered component of the Acheulian lithic inventory of Gesher Benot Ya'aqov (GBY). These tools are an addition to the array of percussive tools (percussors, pitted stones and anvils) made of basalt, flint and limestone. The thin anvils were selected from particularly compact, horizontally fissured zones of basalt flows. This type of fissuring produces a natural geometry of thick and thin slabs. Hominins at GBY had multiple acquisition strategies, including the selection of thick slabs for the production of giant cores and cobbles for percussors. The selection of thin slabs was carried out according to yet another independent and targeted plan. The thinness of the anvils dictated a particular range of functions. The use of the anvils is well documented on their surfaces and edges. Two main types of damage are identified: those resulting from activities carried out on the surfaces of the anvils and those resulting from unintentional forceful blows (accidents de travaille). Percussive activities that may have been associated with the thin anvils include nut cracking and the processing of meat and bones, as well as plants. PMID:26483531

  13. Evidence for the predominance of mid-tropopheric aerosols as subtropical anvil nuclei

    SciTech Connect

    Fridland, A; Ackermann, A; Jensen, E; Stevens, D

    2004-04-26

    NASA's recent CRYSTAL-FACE field experiment focused on anvil cirrus clouds, an important but poorly understood element of our climate system. Data obtained include the first comprehensive measurements of aerosols and cloud particles throughout the atmospheric column during the evolution of multiple deep convective storm systems. Coupling these new measurements with detailed cloud simulations that resolve the size distributions of aerosols and cloud particles, we find several lines of evidence that most anvil crystals form on mid-tropospheric rather than boundary layer aerosols. This result defies conventional wisdom and indicates that distant pollution sources may impact anvil clouds more than local sources.

  14. High-pressure generation using double stage micro-paired diamond anvils shaped by focused ion beam

    SciTech Connect

    Sakai, Takeshi Ohfuji, Hiroaki; Yagi, Takehiko; Irifune, Tetsuo; Ohishi, Yasuo; Hirao, Naohisa; Suzuki, Yuya; Kuroda, Yasushi; Asakawa, Takayuki; Kanemura, Takashi

    2015-03-15

    Micron-sized diamond anvils with a 3 μm culet were successfully processed using a focused ion beam (FIB) system and the generation of high pressures was confirmed using the double stage diamond anvil cell technique. The difficulty of aligning two second-stage micro-anvils was solved via the paired micro-anvil method. Micro-manufacturing using a FIB system enables us to control anvil shape, process any materials, including nano-polycrystalline diamond and single crystal diamond, and assemble the sample exactly in a very small space between the second-stage anvils. This method is highly reproducible. High pressures over 300 GPa were achieved, and the pressure distribution around the micro-anvil culet was evaluated by using a well-focused synchrotron micro-X-ray beam.

  15. High-pressure generation using double stage micro-paired diamond anvils shaped by focused ion beam

    NASA Astrophysics Data System (ADS)

    Sakai, Takeshi; Yagi, Takehiko; Ohfuji, Hiroaki; Irifune, Tetsuo; Ohishi, Yasuo; Hirao, Naohisa; Suzuki, Yuya; Kuroda, Yasushi; Asakawa, Takayuki; Kanemura, Takashi

    2015-03-01

    Micron-sized diamond anvils with a 3 μm culet were successfully processed using a focused ion beam (FIB) system and the generation of high pressures was confirmed using the double stage diamond anvil cell technique. The difficulty of aligning two second-stage micro-anvils was solved via the paired micro-anvil method. Micro-manufacturing using a FIB system enables us to control anvil shape, process any materials, including nano-polycrystalline diamond and single crystal diamond, and assemble the sample exactly in a very small space between the second-stage anvils. This method is highly reproducible. High pressures over 300 GPa were achieved, and the pressure distribution around the micro-anvil culet was evaluated by using a well-focused synchrotron micro-X-ray beam.

  16. A Combined MCS and Refraction Study of the Convergent Nicaraguan Margin

    NASA Astrophysics Data System (ADS)

    Berhorst, A.; Flueh, E. R.; McIntosh, K.; Ranero, C. R.; Walther, C. H.; Dole, J.

    2001-12-01

    The presented seismic profile is part of an extensive MCS and wide-angle survey. The seismic measurements were carried out using a 6 km long streamer, 14 ocean bottom hydrophones (OBH) and 12 landstations recording marine airgun shots. One important objective of this study is the imaging of the subduction zone from the trench to the coast and the determination of the margin P-wave velocity structure. The image of the upper seismogenic plate boundary zone beneath the shelf should improve the knowledge of the seismogenic character and the evolution of this convergent margin. The profile was acquired during a cruise with the R/V Maurice Ewing as part of the MARGINS program. The purpose of this seismic investigation was to improve the scarce knowledge about the structure of the Nicaraguan margin, which is located between the intensively studied margins of Guatemala to the north and Costa Rica to the south.

  17. Using observational retrievals to expose precipitation and convective dynamics biases in simulations of a tropical MCS

    NASA Astrophysics Data System (ADS)

    Varble, A.; Zipser, E. J.

    2013-12-01

    Realistically simulating convective and stratiform structures of mesoscale convective systems (MCSs) requires proper representation of the large-scale environment and adequate representation of convective dynamics and parameterized microphysics in the simulation. The partitioning and areal coverage of such structures determine the heating distribution of any given system, thus affecting the large-scale dynamic response to the system. This issue is becoming evermore relevant with increasing computing power that will allow numerical weather prediction and global climate models to approach 1-10 km horizontal grid spacing in the coming decades. To test whether mesoscale simulations using 1-km grid spacing properly simulate a large tropical monsoonal MCS, several cloud-resolving model (CRM) and limited area model (LAM) simulations of a Tropical Warm Pool-International Cloud Experiment (TWP-ICE) MCS are compared with several observational retrievals. These comparisons expose a high bias in convective radar reflectivity aloft and a low bias in stratiform rainfall. Combined with errors due to large-scale environmental biases, model setup, and bulk microphysics parameterization assumptions, these biases appear related to overly intense deep convection in the simulations based on comparisons with dual-Doppler retrieved vertical velocity. The difference between simulated and dual-Doppler retrieved vertical velocity is especially large in the upper troposphere. This upper tropospheric difference is partially due to lofting and freezing of large rain water contents in simulations, which leads to large increases in buoyancy through latent heating. Possible reasons for overly intense simulated convective updrafts with large condensate loadings at mid and upper levels are explored.

  18. How well does CO emission measure the H2 mass of MCs?

    NASA Astrophysics Data System (ADS)

    Szűcs, László; Glover, Simon C. O.; Klessen, Ralf S.

    2016-07-01

    We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain 12CO and 13CO emission maps for the J = 1 → 0 rotational transition. The emission maps are analysed with commonly used observational methods, i.e. the 13CO column density measurement, the virial mass estimate and the so-called XCO (also CO-to-H2) conversion factor, and then the inferred quantities (i.e. mass and column density) are compared to the physical values. We generally find that most methods examined here recover the CO-emitting H2 gas mass of MCs within a factor of 2 uncertainty if the metallicity is not too low. The exception is the 13CO column density method. It is affected by chemical and optical depth issues, and it measures both the true H2 column density distribution and the molecular mass poorly. The virial mass estimate seems to work the best in the considered metallicity and radiation field strength range, even when the overall virial parameter of the cloud is above the equilibrium value. This is explained by a systematically lower virial parameter (i.e. closer to equilibrium) in the CO-emitting regions; in CO emission, clouds might seem (sub-)virial, even when, in fact, they are expanding or being dispersed. A single CO-to-H2 conversion factor appears to be a robust choice over relatively wide ranges of cloud conditions, unless the metallicity is low. The methods which try to take the metallicity dependence of the conversion factor into account tend to systematically overestimate the true cloud masses.

  19. Quasi-Stationary Shear-parallel MCS in a Near-saturated Environment

    NASA Astrophysics Data System (ADS)

    Liu, Changhai; Moncrieff, Mitchell

    2016-04-01

    Idealized simulations are performed to investigate a poorly-understood category of Mesoscale Convective Systems (MCSs) - quasi-stationary convective lines with upstream-building and downstream stratiform observed in very moist environments. A specific feature in the experimental design is the inclusion of a highly idealized moisture front, mimicking the water vapor variations across the large-scale quasi-stationary (Mei-Yu) front during the Asian summer monsoon, where this regime of convective organization has been frequently observed. The numerical experiment with a wind profile of significant low-level vertical shear, plus a moist thermodynamic sounding with low convective inhibition, generates a long-lasting convective system which is down-shear tilted with a morphology resembling the documented MCSs with back-building or parallel stratiform in East Asia and North America. This is the first successful simulations of the carrot-like MCS morphology, where cells initiate near the upstream edge in either back-building or forward-building form depending on the system propagation direction. A major disparity from most types of MCSs, especially the well-studied squall line, is the weak and shallow cold pool and its negligible effect on system sustenance and propagation. Instead of the cold-pool-shear interaction, it is found that convectively-excited gravity waves are responsible for the intermittent upstream initiation of convective elements. Sensitivity tests show that both the moisture front and shear are critical for this MCS category. Our study suggests that the background spatial moisture variability affects the selection of the modes of organization, and that a systematic investigation of its role in convective organization in various wind shear conditions should be explored.

  20. Structure and activity of the imbricated wedge of the Gulf of Cadiz from MCS images

    NASA Astrophysics Data System (ADS)

    Calahorrano Betancourt, Alcinoe; Ranero, César R.; Gràcia, Eulàlia

    2015-04-01

    In this work we present new results on the structure and activity of the imbricated wedge of the Gulf of Cadiz based on ˜ 3000 km of multichannel (MCS) profiles acquired off NW Moroccan margin. Seismic images indicates that the imbricated wedge is bounded between the Gulf of Cadiz margin at the north, the Kenitra margin at the south and the Rharb margin at the east. It is imaged as a sedimentary body with variable seismic amplitude, and structured by imbricated thrust sheets similar to an accretionary prism. Its maximum thickness is located at the east region of the gulf. It gradually thins toward the center and south of the gulf, where it is buried by ˜0.3 twts of sedimentary deposits, indicating that the imbricated wedge is actually not growing. It probably stops it s activity at ˜5-6 Ma. The imbricated wedge is overlaid by sedimentary sequences whose oldest unit is uppermost Tortonian. No evidences of gravitational (olistostrom) origin were founded. Active deformation related to plate convergence corresponds mainly to strike-slip faulting and minor thrusting. Mud diapirism is imaged intruding both the imbricated wedge and the overlaying sediments. At the south, the seismic images show normal faulting probably related with an extended continental crust or a continent-ocean transition crust. The age of this extension is probably Triassic-Jurassic, and we propose it as the conjugated margin of the Gulf of Cadiz. Toward the east, MCS profiles image high-amplitude continent-verging reflections corresponding to pervasive normal faulting. These deformation related to a extended terrain, named Rharb margin, seems to act as the backstop of the imbricated wedge, and it is over-thrusted by Prebetic/Flysh sequences off the Strait of Gibraltar.

  1. Users Guide for the Anvil Threat Corridor Forecast Tool V1.7.0 for AWIPS

    NASA Technical Reports Server (NTRS)

    Bauman, William H., III

    2007-01-01

    The Applied Meteorology Unit (AMU) originally developed the Anvil Threat Sector Tool for the Meteorological Interactive Data Display System (MIDDS) and delivered the capability in three phases beginning with a feasibility study in 2000 and delivering the operational final product in December 2003. This tool is currently used operationally by the 45th Weather Squadron (45 WS) Launch Weather Officers (LWO) and Spaceflight Meteorology Group (SMG) forecasters. Phase I of the task established the technical feasibility of developing an objective, observations-based tool for short-range anvil forecasting. The AMU was subsequently tasked to develop short-term anvil forecasting tools to improve predictions of the threat of triggered lightning to space launch and landing vehicles. Under the Phase II effort, the AMU developed a nowcasting anvil threat sector tool, which provided the user with a threat sector based on the most current radiosonde upper wind data from a co-located or upstream station. The Phase II Anvil Threat Sector Tool computes the average wind speed and direction in the layer between 300 and 150 mb from the latest radiosonde for a user-designated station. The following threat sector properties are consistent with the propagation and lifetime characteristics of thunderstorm anvil clouds observed over Florida and its coastal waters (Short et al. 2002): a) 20 n mi standoff circle, b) 30 degree sector width, c) Orientation given by 300 to 150 mb average wind direction, d) 1-, 2-, and 3- hour arcs in upwind direction, and e) Arc distances given by 300 to 150 mb average wind speed. Figure 1 is an example of the MIDDS Anvil Threat Sector tool overlaid on a visible satellite image at 2132 UTC 13 May 2001. Space Launch Complex 39A was selected as the center point and the Anvil Threat Sector was determined from upper-level wind data at 1500 UTC in the preconvective environment. Narrow thunderstorm anvil clouds extend from central Florida to the space launch and

  2. Evidence for the predominance of mid-tropospheric aerosols as subtropical anvil cloud nuclei.

    PubMed

    Fridlind, Ann M; Ackerman, Andrew S; Jensen, Eric J; Heymsfield, Andrew J; Poellot, Michael R; Stevens, David E; Wang, Donghai; Miloshevich, Larry M; Baumgardner, Darrel; Lawson, R Paul; Wilson, James C; Flagan, Richard C; Seinfeld, John H; Jonsson, Haflidi H; VanReken, Timothy M; Varutbangkul, Varuntida; Rissman, Tracey A

    2004-04-30

    NASA's recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment focused on anvil cirrus clouds, an important but poorly understood element of our climate system. The data obtained included the first comprehensive measurements of aerosols and cloud particles throughout the atmospheric column during the evolution of multiple deep convective storm systems. Coupling these new measurements with detailed cloud simulations that resolve the size distributions of aerosols and cloud particles, we found several lines of evidence indicating that most anvil crystals form on mid-tropospheric rather than boundary-layer aerosols. This result defies conventional wisdom and suggests that distant pollution sources may have a greater effect on anvil clouds than do local sources. PMID:15118158

  3. Diamond-anvil high-pressure cell for optical spectroscopy at low temperature

    NASA Astrophysics Data System (ADS)

    Kobayashi, Toshihiko

    1985-02-01

    A diamond-anvil high-pressure cell is described which allows optical studies at low temperatures and variable pressure to 260 kbar and higher. A bellows assembly has been designed to drive diamond anvils and connected helium gas pressure source. The sample pressure can be changed remotely while the sample is maintained at operating temperature. Examples of the application to the optical absorption in InP under high pressure are shown. Tests using different pressure transmitting fluids are reported.

  4. Note: Simple and portable setup for loading high purity liquids in diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Olejnik, Ella; Deemyad, Shanti

    2016-03-01

    Here we explain a simple and inexpensive procedure to preserve the original purity of the liquid samples during the loading process in a diamond anvil cell. The idea is to keep the sample in frozen form during the loading process while preventing the condensation of the water or other introduction of contaminants. The system can be quickly and easily assembled in a basic laboratory setup. This process can be used for loading some of the common pressure media in a diamond anvil cell.

  5. Anvil Forecast Tool in the Advanced Weather Interactive Processing System, Phase II

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III

    2008-01-01

    Meteorologists from the 45th Weather Squadron (45 WS) and Spaceflight Meteorology Group have identified anvil forecasting as one of their most challenging tasks when predicting the probability of violations of the Lightning Launch Commit Criteria and Space Light Rules. As a result, the Applied Meteorology Unit (AMU) created a graphical overlay tool for the Meteorological Interactive Data Display Systems (MIDDS) to indicate the threat of thunderstorm anvil clouds, using either observed or model forecast winds as input.

  6. First tests of THz transmission through a Diamond Anvil Cell

    SciTech Connect

    John Klopf

    2011-01-24

    The THz source generated by the accelerator driver for the Jefferson Lab Free Electron Laser is unique in the world in its ability to deliver a high average power beam of ultrashort (<500 fs FWHM) broadband THz pulses. The spectrum of this source presents an ideal probe for many low energy phenomena, and the time structure enables measurement of dynamic processes with sub-ps resolution. An outline of the range of potential applications for this THz source as a probe of sub-ps dynamics in materials under extreme conditions will be presented. To demonstrate the capabilities of this source for just such experiments, the first set of tests to characterize the transmission of the THz beam through a diamond anvil cell (DAC) have been performed. These preliminary results will be presented along with a description of the optical design used to deliver the THz beam into and out of the DAC. The current design will be compared with other possible techniques and the plans for the next set of measurements will also be given.

  7. EOS calculations for hydrothermal diamond anvil cell operation.

    PubMed

    Presser, Volker; Heiss, Martin; Nickel, Klaus G

    2008-08-01

    The hydrothermal diamond anvil cell (HDAC) is an excellent tool for high-temperature, high-pressure (hydrothermal) experiments. For an accurate determination of pressure induced by a certain temperature in an isochoric sample chamber volume, an equation of state (EOS) of water can be used instead of direct measurement. This paper reviews the theoretic background and provides all needed equations for the application of EOS of water to HDAC experiments summarizing state-of-the-art knowledge and incorporating up-to-date thermodynamic data. The p-T conditions determined using the IAPWS-95 formulation for the thermodynamic properties of ordinary water are in agreement with values obtained from direct methods or other established EOS formulations. In particular, (1) the calculation of density through the (a) melting point or (b) homogenization method along with determining (2) pressure as a function of density and temperature or (3) density as a function of pressure and temperature is explained. As a new aspect in the context of HDAC operations, the critical influence of nucleation and a strategy to overcome this problem are discussed. Furthermore, we have derived new polynomial equations, which allow the direct calculation of the fluid phase's density from the melting temperature. These are implemented in a spreadsheet program, which is freely available for interested users. PMID:19044377

  8. Applications of sample nanofabrication in diamond-anvil cell experiments

    NASA Astrophysics Data System (ADS)

    Pigott, J. S.; Fischer, R. A.; Hrubiak, R.; Scott, H. P.; Panero, W. R.

    2015-12-01

    We use electron gun evaporation, sputter deposition, and photolithography to fabricate samples for laser-heated diamond anvil cell experiments. With complimentary thermal modeling, the sample geometry can be optimized and tailored to the experimental application. Here we highlight equation of state studies using nanofabricated double-hot plate samples. The homogeneous samples produced by our methods lead to exceptionally even heating both spatially and temporally that produced high-quality equations of state for nickel and stishovite. The Fe and Pt mutual equations of state may be well characterized and we show recent progress in fabricating samples consisting of a layered stack of Pt/SiO2/Fe/SiO2 in which the SiO2 serves to prevent the alloying of Fe and Pt. Finally, by exploiting state-of-the art nanofabrication techniques, we explore a wider range of the potential applications of such samples including high-pressure, high-temperature diffusion, melting, and thermal conductivity. Using the TempDAC code, we investigate the ideal sizes and ratios of the sample, heating laser diameter, and x-ray spot size while quantifying the effect of x-ray misalignment.

  9. Portable laser-heating system for diamond anvil cells

    SciTech Connect

    Dubrovinsky, L.; Glazyrin, K.; McCammon, C.; Narygina, O.; Greenberg, E.; Ubelhack, S.; Chumakov, A.I.; Pascarelli, S.; Prakapenka, V.; Bock, J.; Dubrovinskaia, N.

    2009-10-21

    The diamond anvil cell (DAC) technique coupled with laser heating has become the most successful method for studying materials in the multimegabar pressure range at high temperatures. However, so far all DAC laser-heating systems have been stationary: they are linked either to certain equipment or to a beamline. Here, a portable laser-heating system for DACs has been developed which can be moved between various analytical facilities, including transfer from in-house to a synchrotron or between synchrotron beamlines. Application of the system is demonstrated in an example of nuclear inelastic scattering measurements of ferropericlase (Mg{sub 0.88}Fe{sub 0.12})O and h.c.p.-Fe{sub 0.9}Ni{sub 0.1} alloy, and X-ray absorption near-edge spectroscopy of (Mg{sub 0.85}Fe{sub 0.15})SiO{sub 3} majorite at high pressures and temperatures. Our results indicate that sound velocities of h.c.p.-Fe{sub 0.9}Ni{sub 0.1} at pressures up to 50 GPa and high temperatures do not follow a linear relation with density.

  10. User Guide for the Anvil Threat Cooridor Forecast Tool V2.4 for AWIPS

    NASA Technical Reports Server (NTRS)

    Barett, Joe H., III; Bauman, William H., III

    2008-01-01

    The Anvil Tool GUI allows users to select a Data Type, toggle the map refresh on/off, place labels, and choose the Profiler Type (source of the KSC 50 MHz profiler data), the Date- Time of the data, the Center of Plot, and the Station (location of the RAOB or 50 MHz profiler). If the Data Type is Models, the user selects a Fcst Hour (forecast hour) instead of Station. There are menus for User Profiles, Circle Label Options, and Frame Label Options. Labels can be placed near the center circle of the plot and/or at a specified distance and direction from the center of the circle (Center of Plot). The default selection for the map refresh is "ON". When the user creates a new Anvil Tool map with Refresh Map "ON, the plot is automatically displayed in the AWIPS frame. If another Anvil Tool map is already displayed and the user does not change the existing map number shown at the bottom of the GUI, the new Anvil Tool map will overwrite the old one. If the user turns the Refresh Map "OFF", the new Anvil Tool map is created but not automatically displayed. The user can still display the Anvil Tool map through the Maps dropdown menu* as shown in Figure 4.

  11. A new multi-anvil press employing six independently acting 8 MN hydraulic rams

    NASA Astrophysics Data System (ADS)

    Manthilake, M. A. G. M.; Walte, N.; Frost, D. J.

    2012-06-01

    A new large volume multi-anvil system which employs six independently acting hydraulic rams with independent oil pressurization systems has been developed for high pressure and temperature experiments. The six 8 MN hydraulic rams approach at right angles inside a composite steel plate frame and can each advance a square faceted anvil of either hardened steel or tungsten carbide. The position of each anvil can be measured relative to the frame of the press to a precision of 0.1 μ m. The press is designed to perform both deformation experiments using cubic ceramic pressure media and experiments employing eight inner cubic anvils to compress an octahedral pressure medium. During compression, the position of each anvil relative to the press frame can be precisely measured and controlled independently, thus ensuring a high level of symmetry in the compressive stress environment. The highly cubic compressive regime provides an optimal environment for the use of inner sintered diamond cubic anvils, which can potentially obtain pressures above 50 GPa. The large loading capacity (24 MN) allows larger cubic pressure media to be used at higher pressures than conventional systems.

  12. Spectral Characteristics of Tropical Anvils Obtained by Combining TRMM Precipitation Radar with Visible and Infrared Scanner Data

    NASA Astrophysics Data System (ADS)

    Yang, Yuan-Jian; Lu, Da-Ren; Fu, Yun-Fei; Chen, Feng-Jiao; Wang, Yu

    2015-06-01

    The spectral characteristics of anvils in tropical areas (25°S-25°N) have been investigated on the basis of data from the tropical rainfall measuring mission's (TRMM) precipitation radar (PR) and a visible and infrared scanner (VIRS), from 1998 to 2007. The anvils' vertical structures were captured by TRMM PR and categorized into two subtypes: ice anvils with an echo base of ≥6 km and mixed anvils with an echo base between 3 and 6 km. Visible and infrared signals for the anvils, which are from reflectance at 0.63 and 1.6 μm (hereafter referred to as RF1 and RF2, respectively) and the equivalent brightness temperatures of a black body at 3.7, 10.8, and 12.0 μm (hereafter referred to as TB3, TB4, and TB5, respectively), were derived simultaneously by use of TRMM VIRS. The findings reveal that the normalized frequency distribution (i.e., probability density functions, PDF) of anvil tops and bases have a bimodal distribution whereas that of anvil thickness has a single-peak curve. For visible signals, the PDF distribution of RF1 (RF2) for anvils, mixed anvils, and ice anvils has an approximately symmetric distribution with a tropics-wide averages of 0.74, 072, and 0.80 (0.21, 0.21, and 0.20), respectively. It can be concluded that ice anvils are optically thicker and contain many more ice-cloud droplets at the cloud top than mixed anvils. RF1 of anvils is usually lower over land than over ocean, by ~0.1, whereas RF2 of anvils is usually higher over land than over ocean, by ~0.3. This implies that anvil clouds have thinner optical depth and their cloud tops consist of many more small ice droplets over land than over ocean. For infrared signals, TB4 is regarded as a representative channel. The PDF distribution of TB4 for anvils and mixed anvils is broad, with tropics-wide averages of 229.2 and 232 K, respectively. They contain two peaks and the secondary peak lies at a much lower value. For ice anvils, the PDF distribution of TB4 is a single-peak curve with a

  13. Analysis of hysteresis effect on the vibration motion of a bimodal non-uniform micro-cantilever using MCS theory

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Korayem, A. H.; Hosseini Hashemi, Sh.

    2016-02-01

    Nowadays, to enhance the performance of atomic force microscopy (AFM) micro-cantilevers (MCs) during imaging, reduce costs and increase the surface topography precision, advanced MCs equipped with piezoelectric layers are utilized. Using the modified couple stress (MCS) theory not only makes the modeling more exhaustive, but also increases the accuracy of prediction of the vibration behavior of the system. In this paper, Hamilton's principle by consideration of the MCS theory has been used to extract the equations. In addition, to discretize the equations, differential quadrature method has been adopted. Analysis of the hysteresis effect on the vibration behavior of the AFM MC is of significant importance. Thus, to model the hysteresis effect, Bouc-Wen method, which is solved simultaneously with the vibration equations of non-uniform Timoshenko beam, has been utilized. Furthermore, a bimodal excitation of the MC has been considered. The results reveal that the hysteresis effect appears as a phase difference in the time response. Finally, the effect of the geometric parameters on the vibration frequency of the system which is excited by combination of the first two vibration modes of the non-uniform piezoelectric MC has been examined. The results indicate the considerable effect of the MC length in comparison with other geometric parameters such as the MC width and thickness.

  14. Secretory prostate apoptosis response (Par)-4 sensitizes multicellular spheroids (MCS) of glioblastoma multiforme cells to tamoxifen-induced cell death

    PubMed Central

    Jagtap, Jayashree C.; Parveen, D.; Shah, Reecha D.; Desai, Aarti; Bhosale, Dipali; Chugh, Ashish; Ranade, Deepak; Karnik, Swapnil; Khedkar, Bhushan; Mathur, Aaishwarya; Natesh, Kumar; Chandrika, Goparaju; Shastry, Padma

    2014-01-01

    Glioblastoma multiforme (GBM) is the most malignant form of brain tumor and is associated with resistance to conventional therapy and poor patient survival. Prostate apoptosis response (Par)-4, a tumor suppressor, is expressed as both an intracellular and secretory/extracellular protein. Though secretory Par-4 induces apoptosis in cancer cells, its potential in drug-resistant tumors remains to be fully explored. Multicellular spheroids (MCS) of cancer cells often acquire multi-drug resistance and serve as ideal experimental models. We investigated the role of Par-4 in Tamoxifen (TAM)-induced cell death in MCS of human cell lines and primary cultures of GBM tumors. TCGA and REMBRANT data analysis revealed that low levels of Par-4 correlated with low survival period (21.85 ± 19.30 days) in GBM but not in astrocytomas (59.13 ± 47.26 days) and oligodendrogliomas (58.04 ± 59.80 days) suggesting low PAWR expression as a predictive risk factor in GBM. Consistently, MCS of human cell lines and primary cultures displayed low Par-4 expression, high level of chemo-resistance genes and were resistant to TAM-induced cytotoxicity. In monolayer cells, TAM-induced cytotoxicity was associated with enhanced expression of Par-4 and was alleviated by silencing of Par-4 using specific siRNA. TAM effectively induced secretory Par-4 in conditioned medium (CM) of cells cultured as monolayer but not in MCS. Moreover, MCS were rendered sensitive to TAM-induced cell death by exposure to conditioned medium (CM)-containing Par-4 (derived from TAM-treated monolayer cells). Also TAM reduced the expression of Akt and PKCζ in GBM cells cultured as monolayer but not in MCS. Importantly, combination of TAM with inhibitors to PI3K inhibitor (LY294002) or PKCζ resulted in secretion of Par-4 and cell death in MCS. Since membrane GRP78 is overexpressed in most cancer cells but not normal cells, and secretory Par-4 induces apoptosis by binding to membrane GRP78, secretory Par-4 is an

  15. Mars Energy Spectrum studies from Assimilated MCS data using the UK MGCM

    NASA Astrophysics Data System (ADS)

    Valeanu, Alexandru; Read, Peter; Wang, Yixiong; Lewis, Stephen; Montabone, Luca; Tabataba-Vakili, Fachreddin

    2015-04-01

    Introduction The energy spectrum (ES) analysis is a renowned tool for understanding the driving mechanisms behind atmospheric turbulence (Lindborg, 1998). We aim to investigate whether energy and enstrophy inertial ranges exist in the kinetic energy spectrum (KES), and to quantify the corresponding cascades (with their ranges), and relationship with the atmospheric forcing and energy dissipation scales. The calculation of the ES from observational data is known to be highly non-trivial due to the lack of global coverage in space and time. Gage and Nastrom (1984) were the first to overcome this problem for Earth but this has not so far been attempted for Mars. Our approach is to take the sparse observational data and assimilate it using a global numerical model. We present preliminary results using the Mars Climate Sounder (MCS) retrievals and the LMD-UK Mars GCM (MGCM). This was pioneered by Lewis and Read (1999). Methodology The equations we used to calculate the Eddy and Zonal Mean kinetic energies are derived from total KES formula presented in Lindborg and Augier (2013). Hence, adding the two spectra together, we obtain the full KES spectrum as presented in their paper. For the Available Potential Energy Spectrum (APES), we have used a preliminary simplified version of the approach presented in Lindborg and Augier (2013). The Energy Spectra To date we have assimilated the MCS data at the resolution of T31 (triangular truncation), hence the ES only spans up to total wavenumber 31. This encompasses a portion of the energy inertial range, which might be expected to manifest the -3 exponential law by analogy with the Earth (Gage & Nastrom, 1984). Features: - velocities and corresponding KEs are higher with increasing height compared to Earth, - "-3" slope is restricted to ~30 km altitude, suggesting an early departure from the enstrophy inertial range, - boundary layer velocities are similar to Earth References 1. Gage and Nastrom, A Climatology of Atmospheric

  16. Observed Enhancement of Reflectivity and Electric Field in Long-Lived Florida Anvils

    NASA Technical Reports Server (NTRS)

    Dye, James E.; Willett, John C.

    2007-01-01

    A study of two long-lived Florida anvils showed that reflectivity greater than 20 dBZ increased in area, thickness and sometimes magnitude at mid-level well downstream of the convective cores. In these same regions electric fields maintained strengths greater than 10 kV m(sup -1) for many tens of minutes and became quite uniform over tens of kilometers. Millimetric aggregates persisted at 9 to 10 km for extended times and distances. Aggregation of ice particles enhanced by strong electric fields might have contributed to reflectivity growth in the early anvil, but is unlikely to explain observations further out in the anvil. The enhanced reflectivity and existence of small, medium and large ice particles far out into the anvil suggest that an updraft was acting, perhaps in weak convective cells formed by instability generated from the evaporation and melting of falling ice particles. We conclude that charge separation must have occurred in these anvils, perhaps at the melting level but also at higher altitudes, in order to maintain fields greater than 10 kV m(sup -1) at 9 to 10 km for extended periods of time over large distances. We speculate that charge separation occurred as a result of ice-ice particle collisions (without supercooled water being present) via either a noninductive or perhaps even an inductive mechanism, given the observed broad ice particle spectra, the strong pre-existing electric fields and the many tens of minutes available for particle interactions. The observations, particularly in the early anvil, show that the charge structure in these anvils was quite complex.

  17. Observed Enhancement of Reflectivity and Electric Field in Long-Lived Florida Anvils

    NASA Technical Reports Server (NTRS)

    Dye, James E.; Willett, John C.

    2007-01-01

    A study of two long-lived Florida anvils showed that reflectivity >20 dBZ increased in area, thickness and sometimes magnitude at mid-level well downstream of the convective cores. In these same regions electric fields maintained strengths >10 kV m1 for many tens of minutes and became quite uniform over tens of kilometers. Millimetric aggregates persisted at 9 to 10 km for extended times and distances. Aggregation of ice particles enhanced by strong electric fields might have contributed to reflectivity growth in the early anvil, but is unlikely to explain observations further out in the anvil. The enhanced reflectivity and existence of small, medium and large ice particles far out into the anvil suggest that an updraft was acting, perhaps in weak convective cells formed by instability generated from the evaporation and melting of falling ice particles. We conclude that charge separation must have occurred in these anvils, perhaps at the melting level but also at higher altitudes, in order to maintain fields >10 kV m 1 at 9 to 10 km for extended periods of time over large distances. We speculate that charge separation occurred as a result of ice-ice particle collisions (without supercooled water being present) via either a non-inductive or perhaps even an inductive mechanism, given the observed broad ice particle spectra, the strong pre-existing electric fields and the many tens of minutes available for particle interactions. The observations, particularly in the early anvil, show that the charge structure in these anvils was quite complex.

  18. Electric Fields, Cloud Microphysics, and Reflectivity in Anvils of Florida Thunderstorms

    NASA Technical Reports Server (NTRS)

    Dye, J. E.; Bateman, M. G.; Christian, H. J.; Defer, E.; Grainger, C. A.; Hall, W. D.; Krider, E. P.; Lewis, S. A.; Mach, D. M.; Merceret, F. J.; Willett, J. C.; Willis, P. T.

    2007-01-01

    A coordinated aircraft - radar project that investigated the electric fields, cloud microphysics and radar reflectivity of thunderstorm anvils near Kennedy Space Center is described. Measurements from two cases illustrate the extensive nature of the microphysics and electric field observations. As the aircraft flew from the edges of anvils into the interior, electric fields very frequently increased abruptly from approximately 1 to more than 10 kV m(exp -1) even though the particle concentration and radar reflectivity increased smoothly. The abrupt increase in field usually occurred when the aircraft entered regions with a reflectivity of 10 to 15 dBZ. It is suggested that the abrupt increase in electric field may be because the charge advection from the storm core did not occur across the entire breadth of the anvil and was not constant in time. Screening layers were not detected near the edges of the anvils. Some long-lived anvils showed subsequent enhancement of electric field and reflectivity and growth of particles, which if localized, might be a factor in explaining the abrupt change of field in some cases. Comparisons of electric field magnitude with particle concentration or reflectivity for a combined data set that included all anvil measurements showed a threshold behavior. When the average reflectivity, such as in a 3-km cube, was less than approximately 5 dBZ, the electric field magnitude was les than kV m(exp -1). Based on these findings, the Volume Averaged Height Integrated Radar Reflectivity (VAHIRR) is now being used by NASA, the Air Force and Federal Aviation Administration in new Lightning Launch Commit Criteria as a diagnostic for high electric fields in anvils.

  19. Electric Fields, Cloud Microphysics, and Reflectivity in Anvils of Florida Thunderstorms

    NASA Technical Reports Server (NTRS)

    Dye, J. E.; Bateman, M. G.; Christian, H. J.; Grainger, C. A.; Hall, W. D.; Krider, E. P.; Lewis, S. A.; Mach, D. M.; Merceret, F. J.; Willett, J. C.; Willis, P. T.

    2006-01-01

    A coordinated aircraft - radar project that investigated the electric fields, cloud microphysics and radar reflectivity of thunderstorm anvils near Kennedy Space Center is described. Measurements from two cases illustrate the extensive nature of the microphysics and electric field observations. As the aircraft flew from the edges of anvils into the interior, electric fields very frequently increased abruptly from approx.1 to >10 kV/m even though the particle concentrations and radar reflectivity increased smoothly. The abrupt increase in field usually occurred when the aircraft entered regions with a reflectivity of 10 to 15 dBZ. It is suggested that the abrupt increase in electric field may be because the charge advection from the storm core did not occur across the entire breadth of the anvil and was not constant in time. Screening layers were not detected near the edges of the anvils. Some long-lived anvils showed subsequent enhancement of electric field and reflectivity and growth of particles, which if localized, might be a factor in explaining the abrupt change of field in some cases. Comparisons of electric field magnitude with particle concentration or reflectivity for a combined data set that included all anvil measurements showed a threshold behavior. When the average reflectivity, such as in a 3-km cube, was less than approximately 5 dBZ, the electric field magnitude was <3 kV/m. Based on these findings, the Volume Averaged Height Integrated Radar Reflectivity (VAHIRR) is now being used by NASA, the Air Force and Federal Aviation Administration in new Lightning Launch Commit Criteria as a diagnostic for high electric fields in anvils.

  20. Geological structure of the offshore Sumatra forearc region estimated from high-resolution MCS reflection survey

    NASA Astrophysics Data System (ADS)

    Misawa, Ayanori; Hirata, Kenji; Seeber, Leonard; Arai, Kohsaku; Nakamura, Yasuyuki; Rahardiawan, Riza; Udrekh; Fujiwara, Toshiya; Kinoshita, Masataka; Baba, Hisatoshi; Kameo, Katsura; Adachi, Keita; Sarukawa, Hiroshi; Tokuyama, Hidekazu; Permana, Haryadi; Djajadihardja, Yusuf S.; Ashi, Juichiro

    2014-01-01

    To investigate detailed fault distributions and shallow geological structure offshore northwestern Sumatra, we obtained high-resolution Multi-Channel Seismic (MCS) reflection data around the Sunda Trench, trench slope, and forearc high regions offshore northwestern Sumatra. In general, trench-parallel anticlinal ridges are distributed from trench slope region to forearc high region. Two kinds of different vergence systems are characterized in the Sumatra forearc region; landward vergence is dominant in the lower trench slope region, and seaward vergence is dominant in the forearc high region. Moreover, piggyback or slope basins are recognized between anticlinal ridges. Deformation in the uppermost part of these basins, that is referred to ‘recent’ deformation in this paper, can be identified not only along major thrusts but also between major thrusts and the lower trench slope, suggesting these are related to recently active faulting. Several but the largest number of such deformation are distributed along a major thrust located in the middle of the forearc high region, whereas few are done along other major thrusts.

  1. The Second Digital Divide and Its Effect on African-American (K-12) School-Age Children

    ERIC Educational Resources Information Center

    Barrett, Christopher A.

    2010-01-01

    The qualitative phenomenological study explored the perceptions of educators and parents of African-American (K-12) school-age children on how the children were using technology. The study was conducted in the Memphis City Public School System (MCS) and was limited to three schools in a school district. Common themes emerged from the analysis of…

  2. Note: Effective anvil size for transverse delamination test of rare-earth-Ba₂Cu₃Oy coated conductor tapes.

    PubMed

    Shin, Hyung-Seop; Gorospe, Alking B; Dedicatoria, Marlon J

    2015-10-01

    In coated conductor (CC) tapes used in magnet and coil applications, delamination due to excessive transverse tensile stresses is still one of the major issues that need considerations. Recently, several methods in evaluating the delamination strength of CC tapes are being used. In the case of anvil test, size of the anvils will be an important factor considering its applications (i.e., superconducting coil impregnation). In this study, delamination strength of CC tape was examined using different upper anvil sizes and their effects were discussed. Finally, reasonable sizes of upper anvil to be used were proposed considering the application conditions. PMID:26521009

  3. View-Angle Dependent AIRS Cloud Radiances: Implication for Tropical Gravity Waves and Anvil Structures

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Gong, Jie

    2011-01-01

    Tropical anvil clouds play important roles in redistributing energy, water in the troposphere. Interacting with dynamics at a wide range of spatial and temporal scales, they can become organized internally and form structured cells, transporting momentum vertically and laterally. To quantify small-scale structures inside cirrus and anvils, we study view-dependence of the cloud-induced radiance from Atmospheric Infrared Sounder (AIRS) using channels near CO2 absorption line. The analysis of tropical eight-year (30degS-30degN, 2003-2010) data suggests that AIRS east-views observe 10% more anvil clouds than westviews during day (13:30 LST), whereas east-views and westviews observe equally amount of clouds at midnight (1 :30 LST). For entire tropical averages, AIRS oblique views observe more anvils than the nadir views, while the opposite is true for deep convective clouds. The dominance of cloudiness in the east-view cannot be explained by AIRS sampling and cloud microphysical differences. Tilted and banded anvil structures from convective scale to mesoscale are likely the cause of the observed view-dependent cloudiness, and gravity wave-cloud interaction is a plausible explanation for the observed structures. Effects of the tilted and banded cloud features need to be further evaluated and taken into account potentially in large-scale model parameterizations because of the vertical momentum transport through cloud wave breaking.

  4. Dependence of Cumulus Anvil Radiative Properties on Environmental Conditions in the Tropical West Pacific

    NASA Technical Reports Server (NTRS)

    Ye, B.; DelGenio, A. D.

    1999-01-01

    Areally extensive, optically thick anvil clouds associated with mesoscale convective clusters dominate the shortwave cloud forcing in the tropics and provide longwave forcing comparable to that of thin cirrus. Changes in the cover and optical thickness of tropical anvils as climate warms can regulate the sign of cloud feedback. As a prelude to the study of MMCR data from the ARM TWP sites, we analyze ISCCP-derived radiative characteristics of anvils observed in the tropical west Pacific during the TOGA-COARE IOP. Anvils with radius greater than 100 km were identified and tracked from inception to decay using the Machado-Rossow algorithm. Corresponding environmental conditions just prior to the start of the convectove event were diagnosed using the Lin-Johnson objective analysis product. Small clusters (100-200 km radius) are observed to have a broad range of optical thicknesses (10-50), while intermediate optical thickness clusters are observed to range in size from 100 km to almost 1000 km. Large-size clusters appear to be favored by strong pre-storm large scale upward motion throughout the troposphere, moist low-to-midlevel relative humidities, environments with slightly higher CAPE than those for smaller clusters, and strong front-to-rear flow. Optically thick anvils are favored in situations of strong low-level moisture convergence and strong upper-level shear.

  5. Behavior of Explosives Under Pressure in a Diamond Anvil Cell

    SciTech Connect

    Foltz, M F

    2006-06-20

    Diamond anvil cell (DAC) studies can yield information about the pressure dependence of materials and reactions under conditions comparable to shock loading. The pressure gradient across the face of the diamonds is often deliberately minimized to create uniform pressure over much of the sample and a simplified data set. To reach very high pressures (30-40 GPa), however, it may be necessary to use ''softer'', high nitrogen content diamonds that are more susceptible to bending under pressure. The resulting enhanced pressure gradient then provides a view of high-pressure behavior under anisotropic conditions similar to those found at the burn front in a bulk sample. We discuss visual observations of pressure-induced changes relative to variations in burn rate of several explosives (Triaminotrinitrobenzene, Nitromethane, CL-20) in the DAC. The burn rate behavior of both Nitromethane (NM) and Triaminotrinitrobenzene (TATB) were previously reported for pressures up to {approx}40 GPa. Nitromethane showed a near monotonic increase in burn rate to a maximum at {approx}30 GPa after which the burn rate decreased, all without color change. At higher pressures, the TATB samples had shiny (metallic) polycrystalline zones or inclusions where the pressure was highest in the sample. Around the shiny zones was a gradation of color (red to yellow) that appeared to follow the pressure gradient. The color changes are believed related to disturbances in the resonance structure of this explosive as the intermolecular separations decrease with pressure. The color and type of residue found in unvented gaskets after the burn was complete also varied with pressure. The four polymorphs of CL-20 ({alpha}, {beta}, {gamma}, {var_epsilon}-Hexanitrohexaazaisowurtzitane, HNIW) did not change color up to the highest pressure applied ({approx}30 GPa), and each polymorph demonstrated a distinctly different burn rate signature. One polymorph {beta} was so sensitive to laser ignition over a narrow

  6. Examination of physical processes of convective cell evolved from a MCS - using a different model initialization

    NASA Astrophysics Data System (ADS)

    Spiridonov, Vlado; Ćurić, Mladjen

    2016-06-01

    The present study is focused on examination of the physical processes of convective cell evolved from a MCS occurred on 4 November 2011 over Genoa, Italy. The Quantitative Precipitation Forecasts (QPF) have been performed using WRF v3.6 model under different configurations and cloud permitting simulations. The results indicate underestimation of the amount of precipitation and spatial displacement of the area with a peak 24-h accumulated rainfall in (mm). Our main objective in the research is to test the cloud model ability and performance in simulation of this particular case. For that purpose a set of sensitivity experiments under different model initializations and initial data have been conducted. The results also indicate that the merging process apparently alters the physical processes through low- and middle-level forcing, increasing cloud depth, and enhancing convection. The examination of the microphysical process simulated by the model indicates that dominant production terms are the accretion of rain by graupel and snow, probabilistic freezing of rain to form graupel and dry and wet growth of graupel. Experiment under WRF v3.6 model initialization has shown some advantage in simulation of the physical processes responsible for production and initiation of heavy rainfall compared to other model runs. Most of the precipitation came from ice-phase particles-via accretion processes and the graupel melting at temperature T0 ≥ 0°C. The rainfall intensity and accumulated rainfall calculated by the model closely reflect the amount of rainfall recorded. Thus, the main benefit is to better resolve convective showers or storms which, in extreme cases, can give rise to major flooding events. In such a way, this model may become major contributor to improvements in weather analysis and small-scale atmospheric predictions and early warnings of such subscale processes.

  7. Progress towards Single Shot Spectroscopic Techniques for Time-Resolved Measurements in the Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Dalton, Douglas Allen; McWilliams, R. Stewart; Mahmood, M. F.; Goncharov, Alexander F.

    2012-02-01

    We will discuss how we are bridging the gap between static diamond anvil cell and dynamic shock experiments using various spectroscopic techniques which utilize nonlinear optics. Using pulsed laser techniques, we can achieve extreme temperatures while probing optical and chemical changes on fast time scales. Recent developments incorporating broadband spectroscopy into the laser heated diamond anvil cell have indicated that probing phase transitions while measuring temperature is possible [1]. Various methods for incorporating nonlinear vibrational spectroscopy (such as CARS) into the diamond anvil cell will be discussed. The application of these optical diagnostics to pulsed laser heating and table-top shock experiments [2] will be presented. [4pt] [1] R.S. McWilliams et al., in preparation. [0pt] [2] M.R. Armstrong et al., J. Appl. Phys., 108, 023511, (2010).

  8. Temperature distributions in the laser-heated diamond anvil cell from 3-D numerical modeling

    SciTech Connect

    Rainey, E. S. G.; Kavner, A.; Hernlund, J. W.

    2013-11-28

    We present TempDAC, a 3-D numerical model for calculating the steady-state temperature distribution for continuous wave laser-heated experiments in the diamond anvil cell. TempDAC solves the steady heat conduction equation in three dimensions over the sample chamber, gasket, and diamond anvils and includes material-, temperature-, and direction-dependent thermal conductivity, while allowing for flexible sample geometries, laser beam intensity profile, and laser absorption properties. The model has been validated against an axisymmetric analytic solution for the temperature distribution within a laser-heated sample. Example calculations illustrate the importance of considering heat flow in three dimensions for the laser-heated diamond anvil cell. In particular, we show that a “flat top” input laser beam profile does not lead to a more uniform temperature distribution or flatter temperature gradients than a wide Gaussian laser beam.

  9. Analysis of resistance-versus-pressure relations for the diamond indentor-anvil system

    NASA Technical Reports Server (NTRS)

    Ruoff, A. L.

    1979-01-01

    Pressures in excess of 1.4 Mbars have been attained by Ruoff and Wanagel (1977) by pressing tiny spherical diamond indentors (tip radius of 2 microns or less) against a diamond anvil. This system has been used for resistance-vs-pressure measurements as follows. A thin (200 A) coherent layer of a conductor, e.g., palladium, can be sputtered on the tip and on the anvil and electrical leads can then be attached to these at points remote from the contact area. Then a thin layer of the sample to be studied can be evaporated, sputtered, or placed on the anvil. When the indentor is pressed against the sample, the resistance changes as the pressure increases and as the contact radius increases. This paper analyzes the resistance-vs-pressure relationship for three different types of resistivity-vs-pressure behavior.

  10. In situ laser heating and radial synchrotron X-ray diffraction ina diamond anvil cell

    SciTech Connect

    Kunz, Martin; Caldwell, Wendel A.; Miyagi, Lowell; Wenk,Hans-Rudolf

    2007-06-29

    We report a first combination of diamond anvil cell radialx-ray diffraction with in situ laser heating. The laser-heating setup ofALS beamline 12.2.2 was modified to allow one-sided heating of a samplein a diamond anvil cell with an 80 W yttrium lithium fluoride laser whileprobing the sample with radial x-ray diffraction. The diamond anvil cellis placed with its compressional axis vertical, and perpendicular to thebeam. The laser beam is focused onto the sample from the top while thesample is probed with hard x-rays through an x-ray transparentboron-epoxy gasket. The temperature response of preferred orientation of(Fe,Mg)O is probed as a test experiment. Recrystallization was observedabove 1500 K, accompanied by a decrease in stress.

  11. Breakthrough in Diamond Anvil Technology: Opening the Door of the Mega-Bar World

    NASA Astrophysics Data System (ADS)

    Yagi, T.

    2011-12-01

    When people started using diamond anvil apparatus at around 1960, no one expected that this type of high-pressure apparatus becomes major tool to study the deep interior of the Earth. Because, sample chamber was very small, pressure value was quite uncertain, high-temperature experiment was difficult, and the pressure range was very limited. Most of these week points were overcame afterwards by various breakthroughs invented by many scientists. Among them, the extension of the pressure range to above one mega bar by H. K. Mao and his colleague at late 1970's was really a big milestone. Since then numerous high-pressure and high-temperature researches have started under the condition corresponding to the Earth's lower mantle and the core. In diamond anvil apparatus, the material used for anvils remain unchanged, still the pressure range was extended more than 100 times from the beginning. I would like to discuss about the key technology which made this breakthrough possible.

  12. Comparative studies of MCs(+)-SIMS and e(-)-beam SNMS for quantitative analysis of bulk materials and layered structures.

    PubMed

    Breuer, U; Holzbrecher, H; Gastel, M; Becker, J S; Dietze, H J

    1995-10-01

    For the quantification of heterostructure depth profiles the knowledge of relative sensitivity factors (RSF) and the influence of matrix effects on the measured profiles is necessary. Matrix dependencies of the measured ion intensities have been investigated for sputtered neutral mass spectrometry (SNMS) and MCs(+)-SIMS. The use of Cs as primary ions for SNMS is advantageous compared to Ar because the depth resolution is improved without changing RSFs determined under Ar bombardment. No significant amount of molecules has been found in the SNMS spectra under Cs bombardment. Using MCs(+)-SIMS the RSFs are matrix dependent. An improvement of depth resolution can be achieved by biasing the sample against the primary ion beam for SNMS due to a reduction of the net energy of the primary ions and a resulting more gracing impact angle. PMID:15048502

  13. Anvil Productivities of Tropical Deep Convective Clusters and Their Regional Differences

    NASA Astrophysics Data System (ADS)

    Deng, Min; Mace, Gerald G.; Wang, Zhien

    2016-06-01

    Tropical deep convection's intensity and their anvil productivity are investigated and compared among 8 climatological regions with 4-year collocated and combined CloudSat and CALIPSO data. For all 8 regions, the convective clusters become deeper, while they become wider and tend to be composed of multiple rainy cores. Among 8 regions, convective clusters at the same scale over EP and AT tend to have less but wider rainy cores than those at WP, MA and IO, while those over AF, IO, MA and AM tend to have higher cloud top than those over ocean. For convective clusters less than 300 km wide over AF and MA, the rainy cores pump more ice mass of larger particles to the mid- and upper troposphere in strong updrafts. The total anvil clouds detrained from convection counts for 0.4 to 0.8 of the cluster horizontal scale, 0.2 to 0.6 of the cluster cross section volume, and 0.05 to 0.20 of the cluster ice mass, depending on the cluster scales and height. There are two main detrainment layers. When the convective clusters is less than about 100 km, the anvil clouds are mainly detrained at about 6-8 km with a spreading ratio (ratio of maximum cluster width to convection rainy core width) less than 1.5. When convective clusters becomes 100 km or wider, it reaches the dominate detrainment layer at about 12 km, the detrainment index increase from 2 to more 6. Among 8 regions, convection clusters in MA produce the most anvil volume fraction. The more the ice mass is pumped upward in the anvil clouds till clusters are about 500 km wider. Nevertheless, the anvil ice mass pumped above 15 km is less than 0.1% of the total ice mass in the convective cluster.

  14. Sequence and batch language programs and alarm-related ``C`` programs for the 242-A MCS. Revision 2

    SciTech Connect

    Berger, J.F.

    1995-03-01

    A Distributive Process Control system was purchased by Project B-534, ``242-A Evaporator/Crystallizer Upgrades``. This control system, called the Monitor and Control System (MCS), was installed in the 242-A Evaporator located in the 200 East Area. The purpose of the MCS is to monitor and control the Evaporator and monitor a number of alarms and other signals from various Tank Farm facilities. Applications software for the MCS was developed by the Waste Treatment Systems Engineering (WTSE) group of Westinghouse. The standard displays and alarm scheme provide for control and monitoring, but do not directly indicate the signal location or depict the overall process. To do this, WTSE developed a second alarm scheme which uses special programs, annunciator keys, and process graphics. The special programs are written in two languages; Sequence and Batch Language (SABL), and ``C`` language. The WTSE-developed alarm scheme works as described below: SABL relates signals and alarms to the annunciator keys, called SKID keys. When an alarm occurs, a SABL program causes a SKID key to flash, and if the alarm is of yellow or white priority then a ``C`` program turns on an audible horn (the D/3 system uses a different audible horn for the red priority alarms). The horn and flashing key draws the attention of the operator.

  15. Note: Moissanite backing plates for use in diamond anvil high pressure cells

    NASA Astrophysics Data System (ADS)

    Pugh, E.

    2016-03-01

    The use of moissanite (single crystal SiC) for backing plates within diamond anvil cells (DACs) has been developed. These have significant technical advantages in certain experiments. For example, moissanite is non-magnetic so is suitable for use in high magnetic fields and for magnetization experiments. Being translucent to light, including x-rays, means that openings are not required in the backing plate and as such has significant mechanical advantages and can provide enhanced scattering angles for x-ray diffraction experiments. The new backing plates have been successfully tested to over 25 GPa using diamond anvils with 0.5 mm culets.

  16. Note: Novel diamond anvil cell for electrical measurements using boron-doped metallic diamond electrodes.

    PubMed

    Matsumoto, R; Sasama, Y; Fujioka, M; Irifune, T; Tanaka, M; Yamaguchi, T; Takeya, H; Takano, Y

    2016-07-01

    A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression. PMID:27475610

  17. Note: Novel diamond anvil cell for electrical measurements using boron-doped metallic diamond electrodes

    NASA Astrophysics Data System (ADS)

    Matsumoto, R.; Sasama, Y.; Fujioka, M.; Irifune, T.; Tanaka, M.; Yamaguchi, T.; Takeya, H.; Takano, Y.

    2016-07-01

    A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression.

  18. Exploring metal hydrides using autoclave and multi-anvil hydrogenations

    NASA Astrophysics Data System (ADS)

    Puhakainen, Kati

    access to new metal hydrides with novel structures and properties, because of the drastically increased chemical potential of hydrogen. Pressures up to 10 GPa can be easily achieved using the multi-anvil (MA) hydrogenations while maintaining sufficient sample volume for structure and property characterization. Gigapascal MA hydrogenations using ammonia borane (BH3

  19. Low-fold, ultra-deep MCS Profiling of the Mariana Arc

    NASA Astrophysics Data System (ADS)

    Tidwell, T.; Klemperer, S. L.; Kerr, B. C.; Goodliffe, A. M.

    2002-12-01

    We collected 2600 km of 12- and 15-fold MCS profiles in April 2002, using the R/V Ewing 6-km 240-channel streamer and a tuned 20-airgun array (10,810 cu. in.). The unusually low fold resulted because our primary focus was OBS wide-angle recording (Kerr et al., this session), so airguns were fired at a shot-interval of 90 to 110 s (shot-spacing of 200 m or 250 m) to allow water-column noise to decay between shots. As a positive aspect we recorded 60 s record lengths (the Syntrak-480 recording system could not record longer traces), so potentially imaging structure to over 200-km depth. We acquired 4 arc-parallel profiles: along the back-arc margin of the Mariana arc 30 km west of the main arc; along the volcanic line from 14°30'N (near Rota) to 18°00'N (latitude of Pagan), 30 km east of the arc along the uplifted forearc high; and along the forearc 80 km east of the arc but 140 km west of the trench. We also shot 6 arc-perpendicular lines to link the arc-parallel lines. All profiles were processed through post-stack migration during the cruise, but to only 20 s travel-time. Despite the low fold, the data provide excellent images of shallow basins between the volcanoes that shed light on the volumes and relative timings of eruptions along the arc, and of normal faults particularly along our eastern fore-arc line. Large and rapid topographic variations along the volcanic arc and uplifted forearc cause significant problems of sideswipe (Gunther et al., this session); and strong water-bottom multiples make recognition of deep structure almost impossible on the preliminarily processed data. However, beneath the shallowest, smoothest bathymetry (the guyot extending north of Farallon de Mendenilla in the uplifted forearc high) clear reflections are seen to 6 s (c. 15 km). In principle our low-frequency high-power source should penetrate deep into the mantle, and our streamer was towed at 12-m depth to minimize swell noise and enhance low-frequency signals. Currently we

  20. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, Curtis L.; Morris, John S.; Agnew, Stephen F.

    1997-01-01

    Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear.

  1. Diamond anvil cell for spectroscopic investigation of materials at high temperature, high pressure and shear

    DOEpatents

    Westerfield, C.L.; Morris, J.S.; Agnew, S.F.

    1997-01-14

    Diamond anvil cell is described for spectroscopic investigation of materials at high temperature, high pressure and shear. A cell is described which, in combination with Fourier transform IR spectroscopy, permits the spectroscopic investigation of boundary layers under conditions of high temperature, high pressure and shear. 4 figs.

  2. Human Motion Tracking and Glove-Based User Interfaces for Virtual Environments in ANVIL

    NASA Technical Reports Server (NTRS)

    Dumas, Joseph D., II

    2002-01-01

    The Army/NASA Virtual Innovations Laboratory (ANVIL) at Marshall Space Flight Center (MSFC) provides an environment where engineers and other personnel can investigate novel applications of computer simulation and Virtual Reality (VR) technologies. Among the many hardware and software resources in ANVIL are several high-performance Silicon Graphics computer systems and a number of commercial software packages, such as Division MockUp by Parametric Technology Corporation (PTC) and Jack by Unigraphics Solutions, Inc. These hardware and software platforms are used in conjunction with various VR peripheral I/O (input / output) devices, CAD (computer aided design) models, etc. to support the objectives of the MSFC Engineering Systems Department/Systems Engineering Support Group (ED42) by studying engineering designs, chiefly from the standpoint of human factors and ergonomics. One of the more time-consuming tasks facing ANVIL personnel involves the testing and evaluation of peripheral I/O devices and the integration of new devices with existing hardware and software platforms. Another important challenge is the development of innovative user interfaces to allow efficient, intuitive interaction between simulation users and the virtual environments they are investigating. As part of his Summer Faculty Fellowship, the author was tasked with verifying the operation of some recently acquired peripheral interface devices and developing new, easy-to-use interfaces that could be used with existing VR hardware and software to better support ANVIL projects.

  3. Static Pressure Above 300 GPa Using Chemical Vapor Deposited Two-stage Diamond Micro-anvils

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey; Samudrala, Gopi; Tsoi, Georgiy; Smith, Spencer; Vohra, Yogesh

    Two-stage diamond micro-anvils were grown via chemical vapor deposition (CVD) on beveled diamond anvils with 30 micron central flats. These anvils were used to compress a pre-indented rhenium foil to pressures in excess of 300 Gigapascals (GPa) at relatively small applied loads. Powder diffraction patterns were collected across the high-pressure region using an x-ray beam collimated to 1x2 microns in a grid with a spacing of 1 micron. While multi-megabar pressures were seen across the entire second stage, the highest pressure regions were confined to areas of a few microns in diameter. These were observed at points near the edge of the second stage with nearby pressure gradients as high as 100 GPa/micron. The transmitted x-rays show that the second stage plastically deformed while maintaining multi-megabar pressures. This may have created a second-stage gasket consisting of CVD diamond and rhenium that supported the pressure gradient without substantial external confining pressure. Further improvements in two-stage diamond micro-anvils would require controlling the geometry and microcrystalline/nanocrystalline diamond content during CVD growth process. This work was supported by the Department of Energy (DOE), National Nuclear Security Administration under Grant Number DE-NA0002014.

  4. A Focusing Laue Monochromator Optimised for Diamond Anvil Cell Diffraction Experiments

    SciTech Connect

    Laundy, David; Lennie, Alistair; Golshan, Mina; Taylor, David; Roberts, Mark; Bushnell-Wye, Graham; Flaherty, John; Burrows, Ian; Cernik, Bob

    2004-05-12

    We have developed a sagittally bent Laue monochromator that is optimised for diffraction experiments on samples in diamond anvil cells. Test measurements have shown that the bandwidth of the monochromatic beam can be broadened with simultaneous focusing of the X-rays. A gain in X-ray flux of over 100 is achieved.

  5. An induction heating diamond anvil cell for high pressure and temperature micro-Raman spectroscopic measurements.

    PubMed

    Shinoda, Keiji; Noguchi, Naoki

    2008-01-01

    A new external heating configuration is presented for high-temperature diamond anvil cell instruments. The supporting rockers are thermally excited by induction from an externally mounted copper coil passing a 30 kHz alternating current. The inductive heating configuration therefore avoids the use of breakable wires, yet is capable of cell temperatures of 1100 K or higher. The diamond anvil cell has no resistive heaters, but uses a single-turn induction coil for elevating the temperature. The induction coil is placed near the diamonds and directly heats the tungsten carbide rockers that support the diamond. The temperature in the cell is determined from a temperature-power curve calibrated by the ratio between the intensities of the Stokes and anti-Stokes Raman lines of silicon. The high-pressure transformation of quartz to coesite is successfully observed by micro-Raman spectroscopy using this apparatus. The induction heating diamond anvil cell is thus a useful alternative to resistively heated diamond anvil cells. PMID:18248060

  6. On the Importance of Small Ice Crystals in Tropical Anvil Cirrus

    NASA Technical Reports Server (NTRS)

    Jensen, E. J.; Lawson, P.; Baker, B.; Pilson, B.; Mo, Q.; Heymsfield, A. J.; Bansemer, A.; Bui, T. P.; McGill, M.; Hlavka, D.; Heymsfield, G.; Platnick, S.; Arnold, G. T.; Tanelli, S.

    2009-01-01

    In situ measurements of ice crystal concentrations and sizes made with aircraft instrumentation over the past two decades have often indicated the presence of numerous relatively small (< 50 m diameter) crystals in cirrus clouds. Further, these measurements frequently indicate that small crystals account for a large fraction of the extinction in cirrus clouds. The fact that the instruments used to make these measurements, such as the Forward Scattering Spectrometer Probe (FSSP) and the Cloud Aerosol Spectrometer (CAS), ingest ice crystals into the sample volume through inlets has led to suspicion that the indications of numerous small ]crystals could be artifacts of large ]crystal shattering on the instrument inlets. We present new aircraft measurements in anvil cirrus sampled during the Tropical Composition, Cloud, and Climate Coupling (TC4) campaign with the 2 ] Dimensional Stereo (2D ]S) probe, which detects particles as small as 10 m. The 2D ]S has detector "arms" instead of an inlet tube. Since the 2D ]S probe surfaces are much further from the sample volume than is the case for the instruments with inlets, it is expected that 2D ]S will be less susceptible to shattering artifacts. In addition, particle inter ]arrival times are used to identify and remove shattering artifacts that occur even with the 2D ]S probe. The number of shattering artifacts identified by the 2D ]S interarrival time analysis ranges from a negligible contribution to an order of magnitude or more enhancement in apparent ice concentration over the natural ice concentration, depending on the abundance of large crystals and the natural small ]crystal concentration. The 2D ]S measurements in tropical anvil cirrus suggest that natural small ]crystal concentrations are typically one to two orders of magnitude lower than those inferred from CAS. The strong correlation between the CAS/2D ]S ratio of small ]crystal concentrations and large ]crystal concentration suggests that the discrepancy is

  7. Life Cycle of Tropical Convection and Anvil in Observations and Models

    NASA Astrophysics Data System (ADS)

    McFarlane, S. A.; Hagos, S. M.; Comstock, J. M.

    2011-12-01

    Tropical convective clouds are important elements of the hydrological cycle and produce extensive cirrus anvils that strongly affect the tropical radiative energy balance. To improve simulations of the global water and energy cycles and accurately predict both precipitation and cloud radiative feedbacks, models need to realistically simulate the lifecycle of tropical convection, including the formation and radiative properties of ice anvil clouds. By combining remote sensing datasets from precipitation and cloud radars at the Atmospheric Radiation Measurement (ARM) Darwin site with geostationary satellite data, we can develop observational understanding of the lifetime of convective systems and the links between the properties of convective systems and their associated anvil clouds. The relationships between convection and anvil in model simulations can then be compared to those seen in the observations to identify areas for improvement in the model simulations. We identify and track tropical convective systems in the Tropical Western Pacific using geostationary satellite observations. We present statistics of the tropical convective systems including size, age, and intensity and classify the lifecycle stage of each system as developing, mature, or dissipating. For systems that cross over the ARM Darwin site, information on convective intensity and anvil properties are obtained from the C-Pol precipitation radar and MMCR cloud radar, respectively, and are examined as a function of the system lifecycle. Initial results from applying the convective identification and tracking algorithm to a tropical simulation from the Weather Research and Forecasting (WRF) model run show that the model produces reasonable overall statistics of convective systems, but details of the life cycle (such as diurnal cycle, system tracks) differ from the observations. Further work will focus on the role of atmospheric temperature and moisture profiles in the model's convective life cycle.

  8. Anvil Forecast Tool in the Advanced Weather Interactive Processing System (AWIPS)

    NASA Technical Reports Server (NTRS)

    Barrett, Joe H., III; Hood, Doris

    2009-01-01

    Launch Weather Officers (LWOs) from the 45th Weather Squadron (45 WS) and forecasters from the National Weather Service (NWS) Spaceflight Meteorology Group (SMG) have identified anvil forecasting as one of their most challenging tasks when predicting the probability of violating the Lightning Launch Commit Criteria (LLCC) (Krider et al. 2006; Space Shuttle Flight Rules (FR), NASA/JSC 2004)). As a result, the Applied Meteorology Unit (AMU) developed a tool that creates an anvil threat corridor graphic that can be overlaid on satellite imagery using the Meteorological Interactive Data Display System (MIDDS, Short and Wheeler, 2002). The tool helps forecasters estimate the locations of thunderstorm anvils at one, two, and three hours into the future. It has been used extensively in launch and landing operations by both the 45 WS and SMG. The Advanced Weather Interactive Processing System (AWIPS) is now used along with MIDDS for weather analysis and display at SMG. In Phase I of this task, SMG tasked the AMU to transition the tool from MIDDS to AWIPS (Barrett et aI., 2007). For Phase II, SMG requested the AMU make the Anvil Forecast Tool in AWIPS more configurable by creating the capability to read model gridded data from user-defined model files instead of hard-coded files. An NWS local AWIPS application called AGRID was used to accomplish this. In addition, SMG needed to be able to define the pressure levels for the model data, instead of hard-coding the bottom level as 300 mb and the top level as 150 mb. This paper describes the initial development of the Anvil Forecast Tool for MIDDS, followed by the migration of the tool to AWIPS in Phase I. It then gives a detailed presentation of the Phase II improvements to the AWIPS tool.

  9. Quality of packed red blood cells and platelet concentrates collected by multicomponent collection using the MCS plus device.

    PubMed

    Leitner, G C; Jilma-Stohlawetz, P; Stiegler, G; Weigel, G; Horvath, M; Tanzmann, A; Höcker, P; Fischer, M B

    2003-01-01

    The demand for blood components is constantly increasing, while the exclusion criteria for donors are strengthened in order to reach maximal safety for donors and patients. To counterbalance reduced availability of volunteers, multicomponent collections (MCC) is an attractive approach to produce more than one component during a single apheresis procedure from one donor, such as packed red blood cells (PRBCs) and platelet concentrates (PCs). Further, the exposures of patients to a limited number of donors reduces the possibility of alloimmunization and transfusion-related diseases. We measured the quality of PRBCs and PCs obtained by MCC, using the MCS+ device with the LDPRBC program, Revision B, and compared them with the quality of manually collected PRBCs and PCs collected with the Revision C2 of the MCS+. We found higher pH levels and lower hemolysis assessed by means of fHb and K+ in the supernatant of PRBCs over the whole storage period of 42 days in MCC-derived PRBCs. The functional metabolism assessed by intracellular ATP was higher in PRBCs collected by MCC than in manually collected units. Furthermore, PCs obtained during MCC showed an increase in p-selectin expression on day 5 of storage compared to PCs collected with the Revision C2 of the MCS+. The p-selectin expression on MCC platelets was within the range of p-selectin expression found in PCs obtained by other apheresis devices. These results indicate less storage lesion in MCC-derived PRBCs compared to manually collected units and no compromise in the quality of MCC PCs obtained in the same apheresis procedure. PMID:12717789

  10. Development of Designer Diamond Anvils for High Pressure-High-Temperature Experiments in Support of the Stockpile Stewardship Program

    SciTech Connect

    Yogesh K. Vohra

    2005-05-12

    The focus of this program at the University of Alabama at Birmingham (UAB) is to develop the next generation of designer diamond anvils that can perform simultaneous joule heating and temperature profile measurements in a diamond anvil cell. A series of tungsten-rhenium thermocouples will be fabricated onto to the anvil and encapsulated by a chemical vapor deposited diamond layer to allow for a complete temperature profile measurement across the anvil. The tip of the diamond anvil will be engineered to reduce the thermal conductivity so that the tungsten-heating coils can be deposited on top of this layer. Several different approaches will be investigated to engineer the tip of the diamond anvil for reduction in thermal conductivity (a) isotopic mixture of 12C and 13C in the diamond layer, (b) doping of diamond with impurities (nitrogen and/or boron), and (c) growing diamond in a higher concentration of methane in hydrogen plasma. Under this academic alliance with Lawrence Livermore National Laboratory (LLNL), PI and his graduate students will use the lithographic and diamond polishing facility at LLNL. This proposed next generation of designer diamond anvils will allow multi-tasking capability with the ability to measure electrical, magnetic, structural and thermal data on actinide materials with unparallel sensitivity in support of the stockpile stewardship program.

  11. The cloud condensation nuclei and ice nuclei effects on tropical anvil characteristics and water vapor of the tropical tropopause layer

    SciTech Connect

    Fan, Jiwen; Comstock, Jennifer M.; Ovchinnikov, Mikhail

    2010-11-10

    Cloud anvils from deep convective clouds are of great importance to the radiative energy budget and the aerosol impact on them is the least understood. Few studies examined the effects of both cloud condensation nuclei (CCN) and ice nuclei (IN) on anvil properties and water vapor content (WVC) in the Tropical Tropopause Layer (TTL). Using a 3-dimensional cloud-resolving model with size-resolved cloud microphysics, we focus on the CCN and IN effects on cloud anvil properties and WVC in the TTL. We find that cloud microphysical changes induced by CCN/IN play a very important role in determining cloud anvil area and WVC in the TTL, whether convection is enhanced or suppressed. Also, CCN effects on anvil microphysical properties, anvil size and lifetime are much more evident relative to IN. IN has little effect on convection, but can increase ice number and mass concentrations significantly under humid conditions. CCN in the PBL is found to have greater effects on convective strength and mid-tropospheric CCN has negligible effects on convection and cloud properties. Convective transport may only moisten the main convective outflow region but the cloud anvil size determines the WVC in the TTL domain. This study shows an important role of CCN in the lower-troposphere in modifying convection, the upper-level cloud properties. It also shows the effects of IN and the PBL CCN on the upper-level clouds depends on the humidity, resolving some contradictory results in past studies. 2

  12. Miniature ceramic-anvil high-pressure cell for magnetic measurements in a commercial superconducting quantum interference device magnetometer.

    PubMed

    Tateiwa, Naoyuki; Haga, Yoshinori; Fisk, Zachary; Ōnuki, Yoshichika

    2011-05-01

    A miniature opposed-anvil high-pressure cell has been developed for magnetic measurement in a commercial superconducting quantum interference device magnetometer. Non-magnetic anvils made of composite ceramic material were used to generate high-pressure with a Cu-Be gasket. We have examined anvils with different culet sizes (1.8, 1.6, 1.4, 1.2, 1.0, 0.8, and 0.6 mm). The pressure generated at low temperature was determined by the pressure dependence of the superconducting transition of lead (Pb). The maximum pressure P(max) depends on the culet size of the anvil: the values of P(max) are 2.4 and 7.6 GPa for 1.8 and 0.6 mm culet anvils, respectively. We revealed that the composite ceramic anvil has potential to generate high-pressure above 5 GPa. The background magnetization of the Cu-Be gasket is generally two orders of magnitude smaller than the Ni-Cr-Al gasket for the indenter cell. The present cell can be used not only with ferromagnetic and superconducting materials with large magnetization but also with antiferromagnetic compounds with smaller magnetization. The production cost of the present pressure cell is about one tenth of that of a diamond anvil cell. The anvil alignment mechanism is not necessary in the present pressure cell because of the strong fracture toughness (6.5 MPa m(1∕2)) of the composite ceramic anvil. The simplified pressure cell is easy-to-use for researchers who are not familiar with high-pressure technology. Representative results on the magnetization of superconducting MgB(2) and antiferromagnet CePd(5)Al(2) are reported. PMID:21639517

  13. Formation of African Easterly Waves and Mesoscale Convective Systems over Eastern Africa and its Implication to Tropical Cyclogenesis over Eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Lin, Yuh-Lang

    2009-07-01

    The formation of African easterly waves and mesoscale convective systems in eastern North Africa and its impacts on the tropical cyclogenesis over the eastern Atlantic Ocean is studied. Based on numerical simulations, AEWs can be produced by vortex shedding from the EH. The lee vortex is generated mainly by the blocking of the EH and helped by the horizontal shear associated with the northeasterly wind and the jet passing through the Turkana channel. The MCS was originated from the moist convection over the EH triggered by diurnal sensible heating. When the MCS moved to the lee of the mountain, it merged with the lee vortex of the AEW train and formed the coupled AEW-MCS system. Numerical simulations of a regional climate model indicate that the simulated fields do possess the AEW characteristics and the convection was generated over the EH, and the pre-Alberto AEW-MCS system was generated near the lee of the EH. Finer-resolution numerical simulations demonstrate that the vortex generated on the lee and MCS over the mountain eventually merge and become an AEW-MCS system which might serve as a precursor of tropical cyclone.

  14. Frontiers of High-Pressure Research: Next Generation Large Volume Gem Anvil Devices

    NASA Astrophysics Data System (ADS)

    Hemley, R. J.; Yan, C.; Xu, J.; Mao, W.; Mao, H.

    2003-12-01

    By any measure, the diamond anvil cell has revolutionized static high-pressure research, and in particular experimental study of Earth and planetary deep interiors. Despite the prowess of the technique, however, its range of applicability is in many ways quite limited and its potential not yet fully realized. We have embarked on a program to develop the next generation high-pressure devices that will allow new classes of in situ high P-T measurements critical to understanding the structure, dynamics, and evolution of planetary bodies. A crucial component of this effort is the enlargement of sample volume without sacrificing the unmatched pressure range and versatility of diamond anvil cells. In conventional studies, pressures to several hundred GPa are generated on sample volumes down to the picoliter range. The small sample size is determined by the availability of perfect diamonds as anvils, which are currently of order of 0.2-0.4 up to a few carats. The small sample size has precluded, or greatly limited the accuracy of, certain classes of high pressure experiments. The production of high-quality single-crystal diamond by microwave plasma chemical vapor deposition (CVD) at very high growth rate of 50-150 μ m/h has opened new opportunities for the creation of large perfect single crystal diamond as anvils.1 This morphology, photoluminescence, Raman spectra, and mechanical properties of the CVD diamond have been examined in detail. Of particular interest is our finding of very high strength and improved optical properties of CVD diamond annealed at high pressures and temperatures.2 In addition, hybrid conventional synthetic/CVD single crystals have been successfully used to generate pressures in the multimegabar range (>200 GPa).3 A parallel initiative involves the continued development of moissanite anvils, which can already be produced as large, perfect crystals and can reach pressures above 60 GPa. Recent advances include the design and fabrication of

  15. The formation and dust lifting processes associated with a large Saharan meso-scale convective system (MCS)

    NASA Astrophysics Data System (ADS)

    Roberts, Alex; Knippertz, Peter

    2013-04-01

    This work focusses on the meteorology that produced a large Mesoscale Convective System (MCS) and the dynamics of its associated cold pool. The case occurred between 8th-10th June 2010 and was initiated over the Hoggar and Aïr Mountains in southern Algeria and northern Niger respectively. The dust plume created covered parts of Algeria, Mali and Mauritania and was later deformed the by background flow and transported over the Atlantic and Mediterranean. This study is based on: standard surface observations (where available), ERA-Interim reanalysis, Meteosat imagery, MODIS imagery, Tropical Rainfall Measuring Mission (TRMM) rainfall estimates, Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat and a high resolution (3.3km) limited area simulation using the Weather Research and Forecasting (WRF) model. A variety of different processes appear to be important for the generation of this MCS and the spreading of the associated dusty cold pool. These include: the presence of a trough on the subtropical jet, the production of a tropical cloud plume, disruption to the structure of the Saharan heat low and the production of a Libyan high. These features produced moistening of the boundary layer and a convergence zone over the region of MCS initiation. Another important factor appears to have been the production of a smaller MCS and cold pool on the evening of the 7th June. This elevated low-level moisture and encouraged convective initiation the following day. Once triggered on the 8th June some cells grew and merged into a single large system that propagated south westward and produced a large cold pool that emanated from its northern edge. The cells on the northern edge of the system over the Hoggar grew and collapsed producing a haboob that spread over a large area. Cells further south continued to develop into the MCS and actively produce a cold pool over the system's lifetime. This undercut the dusty air from the earlier cold pool and

  16. Pulsed neutron powder diffraction at high pressure by a capacity-increased sapphire anvil cell

    NASA Astrophysics Data System (ADS)

    Okuchi, Takuo; Yoshida, Masashi; Ohno, Yoshiki; Tomioka, Naotaka; Purevjav, Narangoo; Osakabe, Toyotaka; Harjo, Stefanus; Abe, Jun; Aizawa, Kazuya; Sasaki, Shigeo

    2013-12-01

    A new design of opposed anvil cell for time-of-flight neutron powder diffraction was prepared for use at advanced pulsed sources. A couple of single-crystal sapphire sphere anvils and a gasket of fully hardened Ti-Zr null alloy were combined to compress 35 mm3 of sample volume to 1 GPa and 11 mm3 to 2 GPa of pressures, respectively. A very high-quality powder diffraction pattern was obtained at Japan Proton Accelerator Research Complex for a controversial high pressure phase of methane hydrate. The counting statistics, resolution, absolute accuracy and d-value range of the pattern were all improved to be best suitable for precise structure refinement. The sample is optically accessible to be measured by Raman and fluorescence spectroscopy during and after compression. The current cell will be an alternative choice to study hydrogenous materials of complex structures that are stable at the described pressure regime.

  17. Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

    SciTech Connect

    Meier, Thomas; Herzig, Tobias; Haase, Jürgen

    2014-04-15

    A new design of a non-magnetic high-pressure anvil cell for nuclear magnetic resonance (NMR) experiments at Giga-Pascal pressures is presented, which uses a micro-coil inside the pressurized region for high-sensitivity NMR. The comparably small cell has a length of 22 mm and a diameter of 18 mm, so it can be used with most NMR magnets. The performance of the cell is demonstrated with external-force vs. internal-pressure experiments, and the cell is shown to perform well at pressures up to 23.5 GPa using 800 μm 6H-SiC large cone Boehler-type anvils. {sup 1}H, {sup 23}Na, {sup 27}Al, {sup 69}Ga, and {sup 71}Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.

  18. Cell assemblies for reproducible multi-anvil experiments (the COMPRES assemblies)

    SciTech Connect

    Leinenweber, Kurt D.; Tyburczy, James A.; Sharp, Thomas G.; Soignard, Emmanuel; Diedrich, Tamara; Petuskey, William B.; Wang, Yanbin; Mosenfelder, Jed L.

    2012-01-31

    The multi-anvil high-pressure technique is an important tool in high-pressure mineralogy and petrology, as well as in chemical synthesis, allowing the treatment of large (millimeter-size) samples of minerals, rocks, and other materials at pressures of a few GPa to over 25 GPa and simultaneous uniform temperatures up to 2500 C and higher. A series of cell assemblies specially designed and implemented for interlaboratory use are described here. In terms of the size of the pressure medium and the anvil truncation size, the five sizes of assemblies developed here are an 8/3, 10/5, 14/8, 18/12, and 25/15 assembly. As of this writing, these assemblies are in widespread use at many laboratories. The details of design, construction, and materials developed or used for the assemblies are presented here.

  19. Integrated-fin gasket for palm cubic-anvil high pressure apparatus

    SciTech Connect

    Cheng, J.-G.; Matsubayashi, K.; Nagasaki, S.; Hisada, A.; Hirayama, T.; Uwatoko, Y.; Hedo, M.; Kagi, H.

    2014-09-15

    We described an integrated-fin gasket technique for the palm cubic-anvil apparatus specialized for the high-pressure and low-temperature measurements. By using such a gasket made from the semi-sintered MgO ceramics and the tungsten-carbide anvils of 2.5 mm square top, we successfully generate pressures over 16 GPa at both room and cryogenic temperatures down to 0.5 K. We observed a pressure self-increment for this specific configuration and further characterized the thermally induced pressure variation by monitoring the antiferromagnetic transition temperature of chromium up to 12 GPa. In addition to enlarge the pressure capacity, such a modified gasket also improves greatly the surviving rate of electrical leads hanging the sample inside a Teflon capsule filled with the liquid pressure-transmitting medium. These improvements should be attributed to the reduced extrusion of gasket materials during the initial compression.

  20. Moissanite anvil cell design for giga-pascal nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Meier, Thomas; Herzig, Tobias; Haase, Jürgen

    2014-04-01

    A new design of a non-magnetic high-pressure anvil cell for nuclear magnetic resonance (NMR) experiments at Giga-Pascal pressures is presented, which uses a micro-coil inside the pressurized region for high-sensitivity NMR. The comparably small cell has a length of 22 mm and a diameter of 18 mm, so it can be used with most NMR magnets. The performance of the cell is demonstrated with external-force vs. internal-pressure experiments, and the cell is shown to perform well at pressures up to 23.5 GPa using 800 μm 6H-SiC large cone Boehler-type anvils. 1H, 23Na, 27Al, 69Ga, and 71Ga NMR test measurements are presented, which show a resolution of better than 4.5 ppm, and an almost maximum possible signal-to-noise ratio.

  1. Efficient graphite ring heater suitable for diamond-anvil cells to 1300 K

    SciTech Connect

    Du Zhixue; Amulele, George; Lee, Kanani K. M.; Miyagi, Lowell

    2013-02-15

    In order to generate homogeneous high temperatures at high pressures, a ring-shaped graphite heater has been developed to resistively heat diamond-anvil cell (DAC) samples up to 1300 K. By putting the heater in direct contact with the diamond anvils, this graphite heater design features the following advantages: (1) efficient heating: sample can be heated to 1300 K while the DAC body temperature remains less than 800 K, eliminating the requirement of a special alloy for the DAC; (2) compact design: the sample can be analyzed with in situ measurements, e.g., x-ray, optical, and electrical probes are possible. In particular, the side access of the heater allows for radial x-ray diffraction (XRD) measurements in addition to traditional axial XRD.

  2. Aerosol-induced changes of convective cloud anvils produce strong climate warming

    NASA Astrophysics Data System (ADS)

    Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

    2010-05-01

    The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm-2. Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvil clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (τ), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds, increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

  3. Moissanite-anvil cells for the electrical transport measurements at low temperatures

    NASA Astrophysics Data System (ADS)

    Yomo, Shusuke; Tozer, Stanley W.

    2010-03-01

    We have successfully measured the Hall effect of a single crystal of a high temperature superconductor La2-xSrxCuO4 in moissanite-anvil high pressure cells. A pressure cell with new Zylon-gasket and wiring arrangement survived under pressure up to at least 5 GPa. Pressure which was clamped at room temperature increased with lowering the temperature down to below 60 K by a factor of 1.3-1.4.

  4. Simple collimator for use with diamond-anvil cells in a synchrotron beam

    NASA Technical Reports Server (NTRS)

    Spain, I. L.; Menoni, C. S.; Black, D. R.

    1984-01-01

    A simple double-slit system is described which allows a synchrotron beam to be collimated onto a small sample (approximately 150-micron diameter) in a diamond-anvil cell using remote control. The apparatus can be constructed easily and inexpensively, and allows the shutter positions to be monitored accurately using readily available electronic equipment. A desirable feature of the collimator is the relatively small time needed for adjustment.

  5. Acoustic detection of cracks in the anvil of a large-volume cubic high-pressure apparatus

    NASA Astrophysics Data System (ADS)

    Yan, Zhaoli; Chen, Bin; Tian, Hao; Cheng, Xiaobin; Yang, Jun

    2015-12-01

    A large-volume cubic high-pressure apparatus with three pairs of tungsten carbide anvils is the most popular device for synthetic diamond production. Currently, the consumption of anvils is one of the important costs for the diamond production industry. If one of the anvils is fractured during the production process, the other five anvils in the apparatus may be endangered as a result of a sudden loss of pressure. It is of critical importance to detect and replace cracked anvils before they fracture for reduction of the cost of diamond production and safety. An acoustic detection method is studied in this paper. Two new features, nested power spectrum centroid and modified power spectrum variance, are proposed and combined with linear prediction coefficients to construct a feature vector. A support vector machine model is trained for classification. A sliding time window is proposed for decision-level information fusion. The experiments and analysis show that the recognition rate of anvil cracks is 95%, while the false-alarm rate is as low as 5.8 × 10-4 during a time window; this false-alarm rate indicates that at most one false alarm occurs every 2 months at a confidence level of 90%. An instrument to monitor anvil cracking was designed based on a digital signal processor and has been running for more than eight months in a diamond production field. In this time, two anvil-crack incidents occurred and were detected by the instrument correctly. In addition, no false alarms occurred.

  6. Acoustic detection of cracks in the anvil of a large-volume cubic high-pressure apparatus.

    PubMed

    Yan, Zhaoli; Chen, Bin; Tian, Hao; Cheng, Xiaobin; Yang, Jun

    2015-12-01

    A large-volume cubic high-pressure apparatus with three pairs of tungsten carbide anvils is the most popular device for synthetic diamond production. Currently, the consumption of anvils is one of the important costs for the diamond production industry. If one of the anvils is fractured during the production process, the other five anvils in the apparatus may be endangered as a result of a sudden loss of pressure. It is of critical importance to detect and replace cracked anvils before they fracture for reduction of the cost of diamond production and safety. An acoustic detection method is studied in this paper. Two new features, nested power spectrum centroid and modified power spectrum variance, are proposed and combined with linear prediction coefficients to construct a feature vector. A support vector machine model is trained for classification. A sliding time window is proposed for decision-level information fusion. The experiments and analysis show that the recognition rate of anvil cracks is 95%, while the false-alarm rate is as low as 5.8 × 10(-4) during a time window; this false-alarm rate indicates that at most one false alarm occurs every 2 months at a confidence level of 90%. An instrument to monitor anvil cracking was designed based on a digital signal processor and has been running for more than eight months in a diamond production field. In this time, two anvil-crack incidents occurred and were detected by the instrument correctly. In addition, no false alarms occurred. PMID:26724059

  7. Acoustic detection of cracks in the anvil of a large-volume cubic high-pressure apparatus

    SciTech Connect

    Yan, Zhaoli Tian, Hao; Cheng, Xiaobin; Yang, Jun; Chen, Bin

    2015-12-15

    A large-volume cubic high-pressure apparatus with three pairs of tungsten carbide anvils is the most popular device for synthetic diamond production. Currently, the consumption of anvils is one of the important costs for the diamond production industry. If one of the anvils is fractured during the production process, the other five anvils in the apparatus may be endangered as a result of a sudden loss of pressure. It is of critical importance to detect and replace cracked anvils before they fracture for reduction of the cost of diamond production and safety. An acoustic detection method is studied in this paper. Two new features, nested power spectrum centroid and modified power spectrum variance, are proposed and combined with linear prediction coefficients to construct a feature vector. A support vector machine model is trained for classification. A sliding time window is proposed for decision-level information fusion. The experiments and analysis show that the recognition rate of anvil cracks is 95%, while the false-alarm rate is as low as 5.8 × 10{sup −4} during a time window; this false-alarm rate indicates that at most one false alarm occurs every 2 months at a confidence level of 90%. An instrument to monitor anvil cracking was designed based on a digital signal processor and has been running for more than eight months in a diamond production field. In this time, two anvil-crack incidents occurred and were detected by the instrument correctly. In addition, no false alarms occurred.

  8. Pulsatile-flow mechanical circulatory support (MCS) as a bridge to transplantation or recovery. Single-centre experience with the POLCAS system in 2014

    PubMed Central

    Kuśmierczyk, Mariusz; Szymański, Jarosław; Juraszek, Andrzej; Kołsut, Piotr; Kuśmierski, Krzysztof; Zieliński, Tomasz; Sobieszczańska-Małek, Małgorzata; Sitkowska-Rysiak, Ewa

    2015-01-01

    Introduction Mechanical circulatory support (MCS) is a recognised method of treatment for patients with end-stage chronic or acute heart failure. The POLCAS pulsatile-flow system has been used in our institution for 15 years. Currently, it is being widely replaced by continuous-flow mechanical circulatory support equipment of the second and third generations (HeartMateII, HeartWare). The MCS presented in this study is associated with a significant risk of complications and its use is increasingly considered controversial. The aim of the study was an evaluation of the results of treatment utilising the POLCAS MCS system at our institution in 2014. Material and methods The POLCAS system was implanted in 12 patients aged 16-63 years (42 ± 17 years) during a period of 12 months (from January to December, 2014). Full-blown cardiogenic shock was observed in all patients before MCS implantation. Four of the analysed patients (33%) required prior circulatory support with other devices: IABP (n = 2) or ECMO (n = 2). Episodes of cardiac arrest were reported in three patients; three other patients experienced serious arrhythmias, which accelerated the decision to implant MCS. The presented data was retrospectively obtained from the CliniNET system of the Institute of Cardiology. OpenOffice Calc spreadsheet was used for data analysis. Results Average MCS time was 41 days ± 25 (from 15 to 91 days). Survival until transplantation or explantation was 91.67%. The most frequent complications following the therapy were: cardiac tamponade or bleeding requiring an intervention – 25% (n = 3), renal failure requiring dialysis – 25% (n = 3), ischaemic stroke associated with the MCS – 16.6% (n = 2), bacteraemia – 16.6% (n = 2), and wound infection – 8% (n = 1). No malfunctions of the MCS system were reported. Early survival in patients who completed the MCS therapy, defined as discharge, amounted to 63.6% (n = 7). Conclusions The POLCAS heart assist system is an effective

  9. Three-dimensional location and waveform analysis of microseismicity in multi-anvil experiments

    NASA Astrophysics Data System (ADS)

    de Ronde, A. A.; Dobson, D. P.; Meredith, P. G.; Boon, S. A.

    2007-12-01

    We present an acoustic emission (AE) monitoring technique to study high-pressure (P > 1 GPa) microseismicity in multi-anvil rock deformation experiments. The application of this technique is aimed at studying fault mechanisms of deep-focus earthquakes that occur during subduction at depths up to 650 km. AE monitoring in multi-anvil experiments is challenging because source locations need to be resolved to a submillimetre scale due to the small size of the experimental assembly. AEs were collected using an 8-receiver array, located on the back truncations of the tungsten carbide anvils. Each receiver consists of a 150-1000 kHz bandwidth PZT transducer assembly. Data were recorded and processed using a high-speed AMSY-5 acquisition system from Vallen-Systems, allowing waveform collection at a 10 MHz sampling rate for each event signal. 3-D hypocentre locations in the assembly are calculated using standard seismological algorithms. The technique was used to monitor fault development in 3 mm long × 1.5 mm diameter olivine cores during axisymmetric compression and extension. The faults were generated during cold compression to ~2 GPa confining pressure. Subsequent AEs at 2-6 GPa and 900 °C were found to locate near these pre-existing faults and exhibit high pressure stick-slip behaviour.

  10. Time differentiated nuclear resonance spectroscopy coupled with pulsed laser heating in diamond anvil cells.

    PubMed

    Kupenko, I; Strohm, C; McCammon, C; Cerantola, V; Glazyrin, K; Petitgirard, S; Vasiukov, D; Aprilis, G; Chumakov, A I; Rüffer, R; Dubrovinsky, L

    2015-11-01

    Developments in pulsed laser heating applied to nuclear resonance techniques are presented together with their applications to studies of geophysically relevant materials. Continuous laser heating in diamond anvil cells is a widely used method to generate extreme temperatures at static high pressure conditions in order to study the structure and properties of materials found in deep planetary interiors. The pulsed laser heating technique has advantages over continuous heating, including prevention of the spreading of heated sample and/or the pressure medium and, thus, a better stability of the heating process. Time differentiated data acquisition coupled with pulsed laser heating in diamond anvil cells was successfully tested at the Nuclear Resonance beamline (ID18) of the European Synchrotron Radiation Facility. We show examples applying the method to investigation of an assemblage containing ε-Fe, FeO, and Fe3C using synchrotron Mössbauer source spectroscopy, FeCO3 using nuclear inelastic scattering, and Fe2O3 using nuclear forward scattering. These examples demonstrate the applicability of pulsed laser heating in diamond anvil cells to spectroscopic techniques with long data acquisition times, because it enables stable pulsed heating with data collection at specific time intervals that are synchronized with laser pulses. PMID:26628151

  11. Time differentiated nuclear resonance spectroscopy coupled with pulsed laser heating in diamond anvil cells

    SciTech Connect

    Kupenko, I. Strohm, C.; McCammon, C.; Cerantola, V.; Petitgirard, S.; Dubrovinsky, L.; Glazyrin, K.; Vasiukov, D.; Aprilis, G.; Chumakov, A. I.; Rüffer, R.

    2015-11-15

    Developments in pulsed laser heating applied to nuclear resonance techniques are presented together with their applications to studies of geophysically relevant materials. Continuous laser heating in diamond anvil cells is a widely used method to generate extreme temperatures at static high pressure conditions in order to study the structure and properties of materials found in deep planetary interiors. The pulsed laser heating technique has advantages over continuous heating, including prevention of the spreading of heated sample and/or the pressure medium and, thus, a better stability of the heating process. Time differentiated data acquisition coupled with pulsed laser heating in diamond anvil cells was successfully tested at the Nuclear Resonance beamline (ID18) of the European Synchrotron Radiation Facility. We show examples applying the method to investigation of an assemblage containing ε-Fe, FeO, and Fe{sub 3}C using synchrotron Mössbauer source spectroscopy, FeCO{sub 3} using nuclear inelastic scattering, and Fe{sub 2}O{sub 3} using nuclear forward scattering. These examples demonstrate the applicability of pulsed laser heating in diamond anvil cells to spectroscopic techniques with long data acquisition times, because it enables stable pulsed heating with data collection at specific time intervals that are synchronized with laser pulses.

  12. Field trial efficacy of Anvil 10+10 and Biomist 31:66 against Ochlerotatus sollicitans in Delaware.

    PubMed

    Lesser, Christopher R

    2002-03-01

    Anvil 10+10 (hereafter Anvil) and Biomist 31:66 (hereafter Biomist) were applied by ground ultra-low volume (ULV) methods to determine the effectiveness of each formulation against Ochlerotatus sollicitans. Each formulation was tested at 50, 67, and 100% of respective maximum label dosage rates. Mosquitoes were exposed in cages on a 3 x 3 grid at distances of 30.5, 60.9, and 91.4 m. Mortality data were collected at intervals of 1, 4, and 12 h after treatment. No significant differences (P > or = 0.05) were found among formulations at applications of 100% of the label rate and no significant differences (P > or = 0.05) were found between Anvil applied at 100% of the label rate and Biomist applied at 50 and 67% of label rates. Ground ULV applications of Anvil at 100% label rate and Biomist at all tested rates were effective (> or = 95% mortality) adulticides. Applications of Anvil at 50 and 67% label rates were significantly less effective (P < or = 0.05) than applications of Biomist at equal percentages of the maximum label rate. Applications of Anvil at rates of 50 and 67% were not effective. PMID:11998928

  13. Quality of life in patients with systemic lupus erythematosus (SLE) compared with related controls within a unique African American population

    PubMed Central

    Barnado, A; Wheless, L; Meyer, AK; Gilkeson, GS; Kamen, DL

    2012-01-01

    The patient’s perspective of how their health affects their function is health-related quality of life (HRQOL). HRQOL is poorer in patients with systemic lupus erythematosus (SLE). Few HRQOL studies in SLE patients have focused on African Americans despite an increased disease burden compared with Caucasians. The African American Gullah population of South Carolina has a homogeneous genetic and environmental background and a high prevalence of multi-patient families with SLE. Demographics, medical history, and Short-Form 36 (SF-36) were measured within a cohort of Gullah SLE cases and related controls. Compared with related controls (n = 37), cases (n = 89) had a lower Physical Component Summary (PCS, 41.8 vs. 52.3, p < 0.01), but not Mental Component Summary (MCS, 55.0 vs. 56.0, p = 0.70). The difference in PCS was no longer significant upon adjustment for working status, disability, and medical conditions. None of the 11 SLE American College of Rheumatology criteria, disease duration, or Systemic Lupus International Collaborating Clinics Damage Index were associated with either PCS or MCS. Cases and controls had similar MCS scores. We hypothesize that this lack of effect of SLE on MCS may be due to disease-coping mechanisms interplaying with cultural factors unique to the Gullah. PMID:22031537

  14. Attributes of mesoscale convective systems at the land-ocean transition in Senegal during NASA African Monsoon Multidisciplinary Analyses 2006

    NASA Astrophysics Data System (ADS)

    Delonge, Marcia S.; Fuentes, Jose D.; Chan, Stephen; Kucera, Paul A.; Joseph, Everette; Gaye, Amadou T.; Daouda, Badiane

    2010-05-01

    In this study we investigate the development of a mesoscale convective system (MCS) as it moved from West Africa to the Atlantic Ocean on 31 August 2006. We document surface and atmospheric conditions preceding and following the MCS, particularly near the coast. These analyses are used to evaluate how thermodynamic and microphysical gradients influence storms as they move from continental to maritime environments. To achieve these goals, we employ observations from NASA African Monsoon Multidisciplinary Analyses (NAMMA) from the NASA S band polarimetric Doppler radar, a meteorological flux tower, upper-air soundings, and rain gauges. We show that the MCS maintained a convective leading edge and trailing stratiform region as it propagated from land to ocean. The initial strength and organization of the MCS were associated with favorable antecedent conditions in the continental lower atmosphere, including high specific humidity (18 g kg-1), temperatures (300 K), and wind shear. While transitioning, the convective and stratiform regions became weaker and disorganized. Such storm changes were linked to less favorable thermodynamic, dynamic, and microphysical conditions over ocean. To address whether storms in different life-cycle phases exhibited similar features, a composite analysis of major NAMMA events was performed. This analysis revealed an even stronger shift to lower reflectivity values over ocean. These findings support the hypothesis that favorable thermodynamic conditions over the coast are a prerequisite to ensuring that MCSs do not dissipate at the continental-maritime transition, particularly due to strong gradients that can weaken West African storms moving from land to ocean.

  15. Tectonic Inversion of the Algerian Continental Margin off Great Kabylia (North Algeria) - Insights from new MCS data (SPIRAL cruise)

    NASA Astrophysics Data System (ADS)

    Aidi, Chafik; Beslier, Marie-Odile; Yelles-Chaouche, Karim; Ribodetti, Alessandra; Bracene, Rabah; Schenini, Laure; Djellit, Hamou; Sage, Françoise; Déverchère, Jacques; Medaouri, Mourad; Klingelhoefer, Frauke; Abtout, Abdeslam; Charvis, Philippe; Bounif, Abdallah

    2014-05-01

    Sub-marine active faulting threatens the coastline of Algeria, as shown by the major Mw 6.9 May 21, 2003 earthquake that occurred in Great Kabylia close to Boumerdes. We present here the structures associated to the Plio-Quaternary (P-Q) tectonic inversion of the central part of the Algerian margin offshore Great Kabylia using new deep multichannel seismic (MCS) lines. Five MCS lines were acquired in the study area during the Algerian-French SPIRAL cruise (September 2009, R/V Atalante). Four lines were acquired using a 3040 cu. in. air-gun array and a 4.5 km 360 channel digital streamer and a 8350 cu. in. source favoring deep penetration was used for one coincident WAS profile and the fifth MCS line. All profiles are pre-stack time migrated and additional pre-stack depth migration was performed in key areas. The MCS lines crosscut the margin from the upper slope to the deep Algero-Provençal Basin either in a N-S direction sub-perpendicular to the structural trend of the margin, or in a NW-SE direction parallel to the actual convergence between Africa and Eurasia plates. Tectonic inversion is expressed on all profiles at the deep margin. The eastern line displays a flat-ramp compressive system in the deep sedimentary series, which emerges at the foot of the continental slope and marks the seaward limit of a P-Q basin perched at mid-slope. The south-dipping ramps are neo-formed structures, whereas the flats use inherited lithologic discontinuities (base of the Messinian evaporitic series, top of the acoustic basement). Westward in the Boumerdes area, the compressive deformation is expressed deeper in the acoustic basement where a southward dipping reflector is interpreted as a blind thrust on top of which all the sedimentary series (Miocene to P-Q) are bent in an antiform that uplifts the base of the Messinian series. A second antiform prolongates this uplift 20 km northward although no clear reverse structure is imaged underneath. These antiforms delimit two

  16. Tectonic Inversion of the Algerian Continental Margin off Great Kabylia (North Algeria) - Insights from new MCS data (SPIRAL cruise)

    NASA Astrophysics Data System (ADS)

    Beslier, M.; Aidi, C.; Yelles-Chaouche, A.; Ribodetti, A.; Bracene, R.; Schenini, L.; Djellit, H.; Sage, F.; Deverchere, J.; Medaouri, M.; Klingelhoefer, F.; Abtout, A.; Charvis, P.; Bounif, A.

    2013-12-01

    Sub-marine active faulting threatens the coastline of Algeria, as shown by the major Mw 6.9 May 21, 2003 earthquake that occurred in Great Kabylia close to Boumerdes. We present here the structures associated to the Plio-Quaternary (P-Q) tectonic inversion of the central part of the Algerian margin offshore Great Kabylia using new deep multichannel seismic (MCS) lines. The large-scale structure of the margin deduced from wide-angle seismic (WAS) data modeling is presented in a companion abstract. Five MCS lines were acquired in the study area during the Algerian-French SPIRAL cruise (September 2009, R/V Atalante). Four lines were acquired using a 3040 cu. in. air-gun array and a 4.5 km 360 channel digital streamer and a 8350 cu. in. source favoring deep penetration was used for one coincident WAS profile and the fifth MCS line. All profiles are pre-stack time migrated and additional pre-stack depth migration was performed in key areas. The MCS lines crosscut the margin from the upper slope to the deep Algero-Provençal Basin either in a N-S direction sub-perpendicular to the structural trend of the margin, or in a NW-SE direction parallel to the actual convergence between Africa and Eurasia plates. Tectonic inversion is expressed on all profiles at the deep margin. The eastern line displays a flat-ramp compressive system in the deep sedimentary series, which emerges at the foot of the continental slope and marks the seaward limit of a P-Q basin perched at mid-slope. The south-dipping ramps are neo-formed structures, whereas the flats use inherited lithologic discontinuities (base of the Messinian evaporitic series, top of the acoustic basement). Westward in the Boumerdes area, the compressive deformation is expressed deeper in the acoustic basement where a southward dipping reflector is interpreted as a blind thrust on top of which all the sedimentary series (Miocene to P-Q) are bent in an antiform that uplifts the base of the Messinian series. A second antiform

  17. African Aesthetics

    ERIC Educational Resources Information Center

    Abiodun, Rowland

    2001-01-01

    No single traditional discipline can adequately supply answers to the many unresolved questions in African art history. Because of the aesthetic, cultural, historical, and, not infrequently, political biases, already built into the conception and development of Western art history, the discipline of art history as defined and practiced in the West…

  18. Temperatures and aerosol opacities of the Mars atmosphere at aphelion: Validation and inter-comparison of limb sounding profiles from MRO/MCS and MGS/TES

    NASA Astrophysics Data System (ADS)

    Shirley, James H.; McConnochie, Timothy H.; Kass, David M.; Kleinböhl, Armin; Schofield, John T.; Heavens, Nicholas G.; McCleese, Daniel J.; Benson, Jennifer; Hinson, David P.; Bandfield, Joshua L.

    2015-05-01

    We exploit the relative stability and repeatability of the Mars atmosphere at aphelion for an inter-comparison of Mars Global Surveyor/Thermal Emission Spectrometer (MGS/TES) and Mars Reconnaissance Orbiter/Mars Climate Sounder (MRO/MCS) nighttime temperature profiles and aerosol opacity profiles in Mars years 25, 26, 29, 30, and 31. Cross-calibration of these datasets is important, as they together provide an extended climatology for this planetary atmosphere. As a standard of comparison we employ temperature profiles obtained by radio occultation methods during the MGS mission in Mars years 24, 25, and 26. We first compare both zonal mean TES limb sounding profiles and zonal mean MCS limb sounding profiles with zonal means of radio occultation temperature profiles for the same season (Ls = 70-80°) and latitudes (55-70°N). We employ a statistical z test for quantifying the degree of agreement of temperature profiles by pressure level. For pressures less than 610 Pa (altitudes > 3 km), the ensemble mean temperature difference between the radio occultation and TES limb sounding profiles found in these comparisons was 1.7 ± 0.7 K. The ensemble mean temperature difference between radio occultation and MCS profiles was 1.4 ± 1.0 K. These differences fall within the formal error estimates for both TES and MCS, validating the accuracy of the instruments and their respective retrieval algorithms. In the second phase of our investigation, we compare aphelion season zonal mean TES limb sounding temperature, water ice opacity, and dust opacity profiles with those obtained at the same latitudes in different years by MCS. The ensemble mean temperature difference found for three comparisons between TES and MCS zonal mean temperature profiles was 2.8 ± 2.1 K. MCS and TES temperatures between 610 Pa and 5 Pa from 55 to 70°N are largely in agreement (with differences < 2 K) when water ice aerosol opacities are comparable. Temperature differences increase when the opacities

  19. Differentiability and retrievability of CO2 and H2O clouds on Mars from MRO/MCS measurements: A radiative-transfer study

    NASA Astrophysics Data System (ADS)

    Hurley, J.; Teanby, N. A.; Irwin, P. G. J.; Calcutt, S. B.; Sefton-Nash, E.

    2014-07-01

    Since the 1970s, it has been predicted that both CO2 and H2O clouds can form in the Martian atmosphere, and many remote-sounding instruments have directly observed layers of extinction asserted to be clouds composed of either CO2 or H2O ice on Mars. The Mars Climate Sounder, onboard the Mars Reconnaissance Orbiter (MRO/MCS), entered orbit around Mars in 2006, and has been providing near-continuous coverage of the full planet since, at wavelengths from visible through to the mid-infrared, primarily in limb-viewing geometry, making it a suitable candidate to study the parameters of these clouds. In this work, the multiple scattering radiative-transfer tool NemesisMCS has been used to create a large dataset of simulations of CO2 and H2O clouds on Mars as would be measured by MRO/MCS, using a range of atmospheric conditions as well as cloud parameters derived from literature suitable for upper atmospheric clouds, and building specifically on the work of Sefton-Nash et al. (2013). This ensemble of simulations has been used to characterise the spectral signature of plausible CO2 and H2O clouds, as well as to assess the suitability of MRO/MCS to observe, to differentiate between, and to derive properties of such clouds. It has been found, given the noise levels expected for MRO/MCS and the range of atmospheric and cloud parameters sampled in this study, that radiance signals introduced by upper atmospheric clouds having nadir optical depths greater than about 10-5 should be distinguishable, with S/N≥1. This corresponds to specific concentrations greater than about 105 particles/g, particle radii greater than around 0.5 μm, and cloud depths greater than about 2 km. MRO/MCS measurements should be able to be used with confidence to differentiate between upper atmospheric cloud and dust in the lower atmosphere, and clear conditions, with high success (≈100%). Lower reliability classification is accomplished for CO2 clouds, with only 60% being correctly identified as CO2

  20. CRYSTAL-FACE Analysis and Simulations of the July 23rd Extended Anvil Case

    NASA Technical Reports Server (NTRS)

    Starr, David

    2003-01-01

    A key focus of CRYSTAL-FACE (Cirrus Regional Study of Tropical Anvils and cirrus Layers - Florida Area Cirrus Experiment) was the generation and subsequent evolution of cirrus outflow from deep convective cloud systems. Present theoretical background and motivations will be discussed. An integrated look at the observations of an extended cirrus anvil cloud system observed on 23 July 2002 will be presented, including lidar and millimeter radar observation; from NASA s ER-2 and in-situ observations from NASA s WB-57 and University of North Dakota Citation. The observations will be compared to results of simulations using 1-D and 2-D high-resolution (100 meter) cloud resolving models. The CRMs explicitly account for cirrus microphysical development by resolving the evolving ice crystal size distribution (bin model) in time and space. Both homogeneous and heterogeneous nucleation are allowed in the model. The CRM simulations are driven using the output of regional simulations using MM5 that produces deep convection similar to what was observed. The MM5 model employs a 2 km inner grid (32 layers) over a 360 km domain, nested within a 6-km grid over a 600-km domain. Initial and boundary conditions for the 36-hour MM5 simulation are taken from NCEP Eta model analysis at 32 km resolution. Key issues to be explored are the settling of the observed anvil versus the model simulations, and comparisons of dynamical properties, such as vertical motions, occurring in the observations and models. The former provides an integrated measure of the validity of the model microphysics (fallspeed) while the latter is the key factor in forcing continued ice generation.

  1. Aerosol-Induced Changes of Convective Cloud Anvils Produce Strong Climate Warming

    NASA Technical Reports Server (NTRS)

    Koren, I.; Remer, L. A.; Altaratz, O.; Martins, J. V.; Davidi, A.

    2010-01-01

    The effect of aerosol on clouds poses one of the largest uncertainties in estimating the anthropogenic contribution to climate change. Small human-induced perturbations to cloud characteristics via aerosol pathways can create a change in the top-of-atmosphere radiative forcing of hundreds of Wm(exp-2) . Here we focus on links between aerosol and deep convective clouds of the Atlantic and Pacific Intertropical Convergence Zones, noting that the aerosol environment in each region is entirely different. The tops of these vertically developed clouds consisting of mostly ice can reach high levels of the atmosphere, overshooting the lower stratosphere and reaching altitudes greater than 16 km. We show a link between aerosol, clouds and the free atmosphere wind profile that can change the magnitude and sign of the overall climate radiative forcing. We find that increased aerosol loading is associated with taller cloud towers and anvils. The taller clouds reach levels of enhanced wind speeds that act to spread and thin the anvi1 clouds, increasing areal coverage and decreasing cloud optical depth. The radiative effect of this transition is to create a positive radiative forcing (warming) at top-of-atmosphere. Furthermore we introduce the cloud optical depth (r), cloud height (Z) forcing space and show that underestimation of radiative forcing is likely to occur in cases of non homogenous clouds. Specifically, the mean radiative forcing of towers and anvils in the same scene can be several times greater than simply calculating the forcing from the mean cloud optical depth in the scene. Limitations of the method are discussed, alternative sources of aerosol loading are tested and meteorological variance is restricted, but the trend of taller clouds; increased and thinner anvils associated with increased aerosol loading remains robust through all the different tests and perturbations.

  2. Tropical anvil characteristics and water vapor of the tropical tropopause layer: Impact of heterogeneous and homogeneous freezing parameterizations

    SciTech Connect

    Fan, Jiwen; Comstock, Jennifer M.; Ovchinnikov, Mikhail; McFarlane, Sally A.; McFarquhar, Greg; Allen, Grant

    2010-06-16

    Abstract Two isolated deep convective clouds (DCCs) that developed in clean-humid and polluted-dry air masses, observed during the TWP-ICE and ACTIVE campaigns, are simulated using a 3-dimensional cloud-resolving model with size-resolved aerosol and cloud microphysics. We examine the impacts of different homogeneous and immersion freezing parameterizations on the anvil characteristics and the water vapor content (WVC) in the Tropical Tropopause Layer (TTL) for the two DCCs that developed in contrasting environments. The modeled cloud properties such as liquid/ice water path and precipitation generally agree with the available radar and satellite retrievals and in situ aircraft measurements. We find that anvil size and anvil microphysical properties such as ice number concentration and ice effective radius (rei) are much more sensitive to the homogeneous freezing parameterization (HomFP) under the polluted-dry condition, while the strength of anvil convection is more sensitive to HomFP under the clean-humid condition. Specifically, the cloud anvil with the Koop et al. (2000) (KOOP) relative humidity dependent scheme has up to 2 and 4 times lower ice number than those with other schemes (temperature dependent) for the clean humid and polluted-dry cases, respectively. Consequently, the rei is increased in both cases, with a larger increase in the polluted-dry case. As a result, extinction coefficient of cloud anvils is reduced by over 25% for the polluted-dry case. Anvil size and evolution are also much affected by HomFPs in the polluted-dry case. Higher immersion-freezing rates leads to a stronger convective cloud, with higher precipitation and ice water path under both humid and dry conditions. As a result, homogeneous freezing rates are enhanced by over 20%. Also, the higher immersion-freezing rate results in stronger convection in cloud anvils, much larger anvil size (up to 3 times) and longer lifetime. The moistening effect of deep convection on the WVC in the

  3. Note: High-pressure in situ x-ray laminography using diamond anvil cell.

    PubMed

    Nomura, Ryuichi; Uesugi, Kentaro

    2016-04-01

    A high-pressure in situ X-ray laminography technique was developed using a newly designed, laterally open diamond anvil cell. A low X-ray beam of 8 keV energy was used, aiming at future application to dual energy X-ray chemical imaging techniques. The effects of the inclination angle and the imaging angle range were evaluated at ambient pressure using the apparatus. Sectional images of ruby ball samples were successfully reconstructed at high pressures, up to approximately 50 GPa. The high-pressure in situ X-ray laminography technique is expected to provide new insights into the deep Earth sciences. PMID:27131721

  4. New Approach to High-Pressure Nuclear Magnetic Resonance with Anvil Cells

    NASA Astrophysics Data System (ADS)

    Meissner, T.; Goh, S. K.; Haase, J.; Meier, B.; Rybicki, D.; Alireza, P. L.

    2010-04-01

    A novel approach that uses radio-frequency microcoils in the high-pressure region of anvil cells with Nuclear Magnetic Resonance (NMR) experiments is described. High-sensitivity Al NMR data at 70 kbar for Al metal are presented for the first time. An expected decrease in the Al Knight shift at 70 kbar is observed, as well as an unexpected change in the local charge symmetry at the Al nucleus. The latter is not predicted by chemical structure analysis under high pressure.

  5. Note: High-pressure in situ x-ray laminography using diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Nomura, Ryuichi; Uesugi, Kentaro

    2016-04-01

    A high-pressure in situ X-ray laminography technique was developed using a newly designed, laterally open diamond anvil cell. A low X-ray beam of 8 keV energy was used, aiming at future application to dual energy X-ray chemical imaging techniques. The effects of the inclination angle and the imaging angle range were evaluated at ambient pressure using the apparatus. Sectional images of ruby ball samples were successfully reconstructed at high pressures, up to approximately 50 GPa. The high-pressure in situ X-ray laminography technique is expected to provide new insights into the deep Earth sciences.

  6. Human Motion Tracking at Marshall Space Flight Center's Collaborative Engineering Center ANVIL

    NASA Technical Reports Server (NTRS)

    Henderson, Steven J.; Hamilton, George S.

    2004-01-01

    The installation and use of electromagnetic human motion trackers requires a specially designed and metal-free environment for optimal performance. Such an area is not readily available at the Marshall Space Flight Center Collaborative Engineering Center ANVIL. Our paper details a systems engineering approach to installing and operating Ascension Technologies Ethernet MotionStar tracking system in a sub-optimal environment, used with the JACK human computer model's motion capture capabilities. We also discuss how this system is integrated into the Marshall Space Flight Center's Human Engineering process.

  7. Obesity and African Americans

    MedlinePlus

    ... Data > Minority Population Profiles > Black/African American > Obesity Obesity and African Americans African American women have the ... ss6304.pdf [PDF | 3.38MB] HEALTH IMPACT OF OBESITY More than 80 percent of people with type ...

  8. SU-E-T-325: The New Evaluation Method of the VMAT Plan Delivery Using Varian DynaLog Files and Modulation Complexity Score (MCS)

    SciTech Connect

    Tateoka, K; Fujimomo, K; Hareyama, M; Saitou, Y; Nakazawa, T; Abe, T; Nakata, A; Yano, M

    2014-06-01

    Purpose: The aim of the study is to evaluate the use of Varian DynaLog files to verify VMAT plans delivery and modulation complexity score (MCS) of VMAT. Methods: Delivery accuracy of machine performance was quantified by multileaf collimator (MLC) position errors, gantry angle errors and fluence delivery accuracy for volumetric modulated arc therapy (VMAT). The relationship between machine performance and plan complexity were also investigated using the modulation complexity score (MCS). Plan and Actual MLC positions, gantry angles and delivered fraction of monitor units were extracted from Varian DynaLog files. These factors were taken from the record and verify system of MLC control file. Planned and delivered beam data were compared to determine leaf position errors and gantry angle errors. Analysis was also performed on planned and actual fluence maps reconstructed from those of the DynaLog files. This analysis was performed for all treatment fractions of 5 prostate VMAT plans. The analysis of DynaLog files have been carried out by in-house programming in Visual C++. Results: The root mean square of leaf position and gantry angle errors were about 0.12 and 0.15, respectively. The Gamma of planned and actual fluence maps at 3%/3 mm criterion was about 99.21. The gamma of the leaf position errors were not directly related to plan complexity as determined by the MCS. Therefore, the gamma of the gantry angle errors were directly related to plan complexity as determined by the MCS. Conclusion: This study shows Varian dynalog files for VMAT plan can be diagnosed delivery errors not possible with phantom based quality assurance. Furthermore, the MCS of VMAT plan can evaluate delivery accuracy for patients receiving of VMAT. Machine performance was found to be directly related to plan complexity but this is not the dominant determinant of delivery accuracy.

  9. Tropical cyclogenesis in Eastern Atlantique: Impact of earlier passage of African Easterly Wave trough on the evolution of Mesoscale Convective Systems and air-sea interaction

    NASA Astrophysics Data System (ADS)

    Lahat Dieng, Abdou; Eymard, Laurence; Moustapha Sall, Saidou; Lazar, Alban; Leduc-Leballeur, Marion

    2014-05-01

    A large part of Atlantic tropical depressions is generated in the Eastern basin in relation with the African Easterly Waves and the Mesoscale Convective Systems coming from the African continent. But initial surface oceanic and atmosphere conditions favoring such evolution are largely unknown. This study analyzes the structures of strengthening and dissipating MCSs evolving near the West African coast and evaluates the role of the surface oceanic condition on their evolutions. Satellite brightness temperature from Meteosat Second Generation over the summer season of 2006 and radar data for the same season between 1993 and 1999 are used to subjectively select fourteen cases of strengthening (dissipating) MCSs when they cross the Senegalese coast. With these observed MCSs locations, a lagged composite analysis is then performed using Era interim and CFSR reanalyses. Results show that the strengthening MCS composite is preceded by prior passage of an AEW near the West African coast. This first trough wave was associated with a cyclonic circulation in the low and middle troposphere and has enhanced southwest wind flow behind him feeding humidly to the strengthening MCS composite which was located in the vicinity of the second AEW trough. The contraction of the wave length associated with the two troughs was probably facilitated this supply in humidity. The Sea Surface Temperature seem contribute to the MCS enhancement through surface evaporation flux but this contribution is less important than humidity advection by the fist system. These conditions were not found in the dissipating MCS case which dissipated in a drying environment air dominated by subsidence and anticyclonic circulation. Key words: Mesoscale Convective System, African Easterly Wave, Sea Surface Temperature, tropical depression.

  10. Turnbuckle diamond anvil cell for high-pressure measurements in a superconducting quantum interference device magnetometer.

    PubMed

    Giriat, Gaétan; Wang, Weiwei; Attfield, J Paul; Huxley, Andrew D; Kamenev, Konstantin V

    2010-07-01

    We have developed a miniature diamond anvil cell for magnetization measurements in a widely used magnetic property measurement system commercial magnetometer built around a superconducting quantum interference device. The design of the pressure cell is based on the turnbuckle principle in which force can be created and maintained by rotating the body of the device while restricting the counterthreaded end-nuts to translational movement. The load on the opposed diamond anvils and the sample between them is generated using a hydraulic press. The load is then locked by rotating the body of the cell with respect to the end-nuts. The dimensions of the pressure cell have been optimized by use of finite element analysis. The cell is approximately a cylinder 7 mm long and 7 mm in diameter and weighs only 1.5 g. Due to its small size the cell thermalizes rapidly. It is capable of achieving pressures in excess of 10 GPa while allowing measurements to be performed with the maximum sensitivity of the magnetometer. The performance of the pressure cell is illustrated by a high pressure magnetic study of Mn(3)[Cr(CN)(6)](2) x xH(2)O Prussian blue analog up to 10.3 GPa. PMID:20687740

  11. Turnbuckle diamond anvil cell for high-pressure measurements in a superconducting quantum interference device magnetometer

    NASA Astrophysics Data System (ADS)

    Giriat, Gaétan; Wang, Weiwei; Attfield, J. Paul; Huxley, Andrew D.; Kamenev, Konstantin V.

    2010-07-01

    We have developed a miniature diamond anvil cell for magnetization measurements in a widely used magnetic property measurement system commercial magnetometer built around a superconducting quantum interference device. The design of the pressure cell is based on the turnbuckle principle in which force can be created and maintained by rotating the body of the device while restricting the counterthreaded end-nuts to translational movement. The load on the opposed diamond anvils and the sample between them is generated using a hydraulic press. The load is then locked by rotating the body of the cell with respect to the end-nuts. The dimensions of the pressure cell have been optimized by use of finite element analysis. The cell is approximately a cylinder 7 mm long and 7 mm in diameter and weighs only 1.5 g. Due to its small size the cell thermalizes rapidly. It is capable of achieving pressures in excess of 10 GPa while allowing measurements to be performed with the maximum sensitivity of the magnetometer. The performance of the pressure cell is illustrated by a high pressure magnetic study of Mn3[Cr(CN)6]2ṡxH2O Prussian blue analog up to 10.3 GPa.

  12. Earth's Core Formation and Composition : New Constraints from Diamond Anvil Cell Experiments

    NASA Astrophysics Data System (ADS)

    Siebert, J.; Badro, J.; Antonangeli, D.; Ryerson, F. J.

    2011-12-01

    The pattern of siderophile (iron-loving) element abundance in the silicate portion of the Earth is a consequence of metal separation during core formation. Thermodynamic expressions used to constrain the metal-silicate partitioning behavior of siderophile elements are mainly established from large volume press experiments that do not cover the full range of potential P-T conditions for core-mantle equilibrium. The diamond anvil cell is the only static technique capable of achieving required P-T conditions but until now its capabilities to perform quantitative metal-silicate partitioning experiments at extreme conditions has been untapped. We use protocols that effectively link high P-T diamond anvil cell with analytical techniques such as focused ion beam device (FIB); NanoSIMS; electron microprobe; transmission electron microscopes; and in-situ synchrotron X-ray diffraction measurements allow us to obtain quantitative data on element partitioning at superliquidus conditions above 30 GPa and 3000 K. Here we present our advances in both experimental and analytical methods. We look at the partitioning of 6 siderophile elements (Ni, Co, Cr, V, Mn, and Nb) that have been extensively studied at lower P-T conditions and constrain the solubility of light elements (Si and O) at these extreme conditions. We then update expressions that describe the partitioning behavior of these elements to address the validity of proposed core formation models (i.e. single-stage core formation model and continuous core formation model).

  13. High-temperature experiments using a resistively heated high-pressure membrane diamond anvil cell.

    PubMed

    Jenei, Zsolt; Cynn, Hyunchae; Visbeck, Ken; Evans, William J

    2013-09-01

    We describe a reliable high performance resistive heating method developed for the membrane diamond anvil cell. This method generates homogenous high temperatures at high pressure in the whole sample for extended operation period. It relies on two mini coil heaters made of Pt-Rh alloy wire mounted around the diamond anvils and gasket, while temperature is monitored by two K-type thermocouples mounted near the sample. The sample, diamonds, and tungsten-carbide seats are thermally insulated from the piston and cylinder keeping the cell temperature below 750 K while the sample temperature is 1200 K. The cell with the heaters is placed in a vacuum oven to prevent oxidation and unnecessary heat loss. This assembly allows complete remote operation, ideally suited for experiments at synchrotron facilities. Capabilities of the setup are demonstrated for in situ Raman and synchrotron x-ray diffraction measurements. We show experimental measurements from isothermal compression at 900 K and 580 K to 100 GPa and 185 GPa, respectively, and quasi-isobaric compression at 95 GPa over 1000 K. PMID:24089873

  14. Validation Study of Unnotched Charpy and Taylor-Anvil Impact Experiments using Kayenta

    SciTech Connect

    Kamojjala, Krishna; Lacy, Jeffrey; Chu, Henry S.; Brannon, Rebecca

    2015-03-01

    Validation of a single computational model with multiple available strain-to-failure fracture theories is presented through experimental tests and numerical simulations of the standardized unnotched Charpy and Taylor-anvil impact tests, both run using the same material model (Kayenta). Unnotched Charpy tests are performed on rolled homogeneous armor steel. The fracture patterns using Kayenta’s various failure options that include aleatory uncertainty and scale effects are compared against the experiments. Other quantities of interest include the average value of the absorbed energy and bend angle of the specimen. Taylor-anvil impact tests are performed on Ti6Al4V titanium alloy. The impact speeds of the specimen are 321 m/s and 393 m/s. The goal of the numerical work is to reproduce the damage patterns observed in the laboratory. For the numerical study, the Johnson-Cook failure model is used as the ductile fracture criterion, and aleatory uncertainty is applied to rate-dependence parameters to explore its effect on the fracture patterns.

  15. CRYSTAL-FACE: A Field Experiment and Modeling Program Focused on Tropical Anvils and Cirrus Layers

    NASA Technical Reports Server (NTRS)

    Jenson, Eric; Gore, Warren J. (Technical Monitor)

    2002-01-01

    The Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE) is a measurement campaign designed to investigate tropical Cirrus cloud physical properties and formation processes. Understanding the production of upper tropospheric cirrus clouds is essential for the successful modeling of 'he Earth's climate. The deployment phase will occur in July, 2002 in southern Florida, USA. Several aircraft will be used, including the ER-2 and Proteus for cloud remote sensing, the WB-57 and Citation for in situ cloud measurements, the P-3 with a Doppler radar for characterization of convective systems, and the Twin otter for sampling of inflow airmasses. In addition, numerous ground-based and satellite remote sensing measurements will be contributing. A central focus of the mission is improvement of our ability to model cirrus clouds with numerical models. Several research groups with a variety of model types (cloud-resolving models, mesoscale models, weather-prediction models, and general circulation models) will be participating. Our hope is to fully characterize several mulonimbus/cirrus anvil systems that can be used as case studies for testing and improvement of the models. The models will be used for investigating cirrus generation and dissipation processes and the sensitivity of tropical cirrus to convective intensity and aerosol properties. Ultimately, we expect this effort to improve our ability to represent tropical cirrus in GCMs. A general description of the CRYSTAL-FACE program will be presented, with an emphasis on the cloud modeling approach.

  16. Characterization of the submesoscale energy cascade in the Alboran Sea thermocline from spectral analysis of high-resolution MCS data

    NASA Astrophysics Data System (ADS)

    Sallares, Valenti; Mojica, Jhon F.; Biescas, Berta; Klaeschen, Dirk; Gràcia, Eulàlia

    2016-06-01

    Part of the kinetic energy that maintains ocean circulation cascades down to small scales until it is dissipated through mixing. While most steps of this downward energy cascade are well understood, an observational gap exists at horizontal scales of 103-101 m that prevents characterizing a key step in the chain: the transition from anisotropic internal wave motions to isotropic turbulence. Here we show that this observational gap can be covered using high-resolution multichannel seismic (HR-MCS) data. Spectral analysis of acoustic reflectors imaged in the Alboran Sea thermocline shows that this transition is likely caused by shear instabilities. In particular, we show that the averaged horizontal wave number spectra of the reflectors vertical displacements display three subranges that reproduce theoretical spectral slopes of internal waves (λx > 100 m), Kelvin-Helmholtz-type shear instabilities (100 m > λx > 33 m), and turbulence (λx < 33 m), indicating that the whole chain of events is occurring continuously and simultaneously in the surveyed area.

  17. Pressure mapping for sphere and half-sphere enhanced diamond anvil cells using synchrotron x-ray diffraction and fluorescence techniques

    NASA Astrophysics Data System (ADS)

    Liu, H.; Liu, L. L.; Cai, Z.; Shu, J.

    2015-12-01

    The measurement for equation of state (EoS) of materials under pressure conditions above 200 GPa is a long-standing challenging subject. Recently, second stage anvil, which was loaded inside the diamond anvil cell (DAC), had been reported by various groups. This method could generate pressure over 300 GPa, or above 600 GPa from the EoS measurement of Re metal between the tiny anvil or 2 half-spheres. Several alternative approaches, using ruby balls, or glassy carbon, or diamond, with single sphere, 2 half-spheres, or multi spheres geometry inside DAC, were tested. The NIST X-ray powder standard, ZnO was selected as pressure marker. Focused ion beam (FIB) was used to cut the half-sphere from diamond anvil top directly to avoid the difficulty of alignment. The synchrotron x-ray diffraction with fine beam size down to 100 nm using zone plate set-up was used to map the pressure gradient at the sphere or half-sphere zone inside DAC. The pressure could be boosted at center of sphere by up to 10 - 70 GPa at about 200 GPa conditions. From broken anvils, trace element analysis using fine focusing synchrotron x-ray fluorescence method revealed the potential anvil damage from FIB cutting the diamond anvil tip, which might decrease the strength of anvils. Fine touch from FIB cutting at final stage using low ion beam current is suggested.

  18. Development of the multi-anvil assembly 6-6 for DIA and D-DIA type high-pressure apparatuses

    SciTech Connect

    Nishiyama, N.; Wang, Y.; Sanehira, T.; Irifune, T.; Rivers, M.L.

    2008-11-12

    A newly designed anvil assembly, Multi-anvil Assembly 6-6 (MA6-6), was developed. This assembly consists of six small anvils with an anvil guide, and can be compressed by DIA-type and deformation-DIA (D-DIA) apparatuses. The use of this anvil assembly simplifies the process of replacing anvils with those having different truncated edge length and/or hardness. As a consequence, the time needed for anvil replacement is significantly shortened. This is a benefit to experiments at synchrotron facilities because anvil replacement has to be carried out within the limited beamtime. Using a combination of an MA6-6 and DIA-type apparatus, pressure above 12 GPa was generated. A deformation experiment of polycrystalline MgO was performed using an MA6-6 with D-DIA at 4 GPa and room temperature. Two-dimensional X-ray diffraction patterns and X-ray radiographic images were collected from the deforming sample using monochromatic X-rays. Quantitative deformation experiments can be carried out using this experimental setup.

  19. MCS Systems Administration Toolkit

    Energy Science and Technology Software Center (ESTSC)

    2001-09-30

    This package contains a number of systems administration utilities to assist a team of system administrators in managing a computer environment by automating routine tasks and centralizing information. Included are utilities to help install software on a network of computers and programs to make an image of a disk drive, to manage and distribute configuration files for a number of systems, and to run self-testss on systems, as well as an example of using amore » database to manage host information and various utilities.« less

  20. Africans in America.

    ERIC Educational Resources Information Center

    Hart, Ayanna; Spangler, Earl

    This book introduces African-American history and culture to children. The first Africans in America came from many different regions and cultures, but became united in this country by being black, African, and slaves. Once in America, Africans began a long struggle for freedom which still continues. Slavery, the Civil War, emancipation, and the…

  1. African Outreach Workshop 1974.

    ERIC Educational Resources Information Center

    Schmidt, Nancy J.

    This report discusses the 1974 African Outreach Workshop planned and coordinated by the African Studies Program at the University of Illinois at Urbana-Champaign. Its major aim was to assist teachers in developing curriculum units on African using materials available in their local community. A second aim was for the African Studies Program to…

  2. Tropical deep convective life cycle: Cb-anvil cloud microphysics from high-altitude aircraft observations

    NASA Astrophysics Data System (ADS)

    Frey, W.; Borrmann, S.; Fierli, F.; Weigel, R.; Mitev, V.; Matthey, R.; Ravegnani, F.; Sitnikov, N. M.; Ulanovsky, A.; Cairo, F.

    2014-12-01

    The case study presented here focuses on the life cycle of clouds in the anvil region of a tropical deep convective system. During the SCOUT-O3 campaign from Darwin, Northern Australia, the Hector storm system has been probed by the Geophysica high-altitude aircraft. Clouds were observed by in situ particle probes, a backscatter sonde, and a miniature lidar. Additionally, aerosol number concentrations have been measured. On 30 November 2005 a double flight took place and Hector was probed throughout its life cycle in its developing, mature, and dissipating stage. The two flights were four hours apart and focused on the anvil region of Hector in altitudes between 10.5 and 18.8 km (i.e. above 350 K potential temperature). Trajectory calculations, satellite imagery, and ozone measurements have been used to ensure that the same cloud air masses have been probed in both flights. The size distributions derived from the measurements show a change not only with increasing altitude but also with the evolution of Hector. Clearly different cloud to aerosol particle ratios as well as varying ice crystal morphology have been found for the different development stages of Hector, indicating different freezing mechanisms. The development phase exhibits the smallest ice particles (up to 300 μm) with a rather uniform morphology. This is indicative for rapid glaciation during Hector's development. Sizes of ice crystals are largest in the mature stage (larger than 1.6 mm) and even exceed those of some continental tropical deep convective clouds, also in their number concentrations. The backscatter properties and particle images show a change in ice crystal shape from the developing phase to rimed and aggregated particles in the mature and dissipating stages; the specific shape of particles in the developing phase cannot be distinguished from the measurements. Although optically thin, the clouds in the dissipating stage have a large vertical extent (roughly 6 km) and persist for at

  3. Shear Deformation of Fe Polycrystals in the Rotational Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Merkel, S.; Lincot, A.; Nisr, C.; Hanfland, M.; Zerr, A.

    2014-12-01

    For many years, experiments are being developed for performing deformation experiments under lower mantle conditions. They include methods such as the Deformation-DIA (Wang et al, 2003) or radial x-ray diffraction in the diamond anvil cell (Merkel et al, 2002). However, the strain applied to the sample is typically limited to about 40%. This can be an issue for studying effects of large deformation or, for the case of diamond anvil cells, applying actual plastic strain at megabar pressures. The issue can be solved using apparatus such as the Rotational-Drickamer (RDA) (e.g. Yamazaki and Karato, 2001). However, the RDA offers limited diffraction access to the sample and operating pressures do not reach those of the lower mantle.In this abstract, we investigate the potential applications of the rotational diamond anvil cell (Rot-DAC) for such studies. 300 K experiments in the Rot-DAC have been performed up to pressures exceeding 50 GPa (e.g. Serebryanaya et al, 1995) with studies focusing on the effect of shear on solid-solid phase transformation pressures. The authors did not investigate the possibility of using the Rot-DAC for studying rheological properties.Here, a sample of polycrystalline Fe is submitted to shear deformation in the Rot-DAC at pressures up to 20 GPa. Synchrotron X-ray diffraction and Rietveld refinements are then used to study the texture and stress state at multiple locations in the sample. The study shows that the Rot-DAC is efficient at producing deformation textures in a polycrystalline aggregate but that care should be taken in ensuring that the sample is actually undergoing plastic deformation and not solid rotation. Stresses, on the other hand, are difficult to extract from the x-ray diffraction data because of lack of understanding of stress distributions in the deforming aggregate.S. Merkel, H. R. Wenk, J. Shu, G. Shen, P. Gillet, H. K. Mao and R. J. Hemley, J. Geophys. Res., 107, 2271 (2002)N. Serebryanaya, V. Blank and V. Ivdenko, Phys

  4. Examination of physical processes of convective cell evolved from a MCS — Using a different model initialization

    NASA Astrophysics Data System (ADS)

    Spiridonov, Vlado; Ćurić, Mladjen

    2016-06-01

    The present study is focused on examination of the physical processes of convective cell evolved from a MCS occurred on 4 November 2011 over Genoa, Italy. The Quantitative Precipitation Forecasts (QPF) have been performed using WRF v3.6 model under different configurations and cloud permitting simulations. The results indicate underestimation of the amount of precipitation and spatial displacement of the area with a peak 24-h accumulated rainfall in (mm). Our main objective in the research is to test the cloud model ability and performance in simulation of this particular case. For that purpose a set of sensitivity experiments under different model initializations and initial data have been conducted. The results also indicate that the merging process apparently alters the physical processes through low- and middle-level forcing, increasing cloud depth, and enhancing convection. The examination of the microphysical process simulated by the model indicates that dominant production terms are the accretion of rain by graupel and snow, probabilistic freezing of rain to form graupel and dry and wet growth of graupel. Experiment under WRF v3.6 model initialization has shown some advantage in simulation of the physical processes responsible for production and initiation of heavy rainfall compared to other model runs. Most of the precipitation came from ice-phase particles-via accretion processes and the graupel melting at temperature T0 ≥ 0°C. The rainfall intensity and accumulated rainfall calculated by the model closely reflect the amount of rainfall recorded. Thus, the main benefit is to better resolve convective showers or storms which, in extreme cases, can give rise to major flooding events. In such a way, this model may become major contributor to improvements in weather analysis and small-scale atmospheric predictions and early warnings of such subscale processes.

  5. Co-Occurrence of Health Conditions during Childhood: Longitudinal Findings from the UK Millennium Cohort Study (MCS)

    PubMed Central

    Law, Catherine; Bedford, Helen; Hope, Steven

    2016-01-01

    Aims To identify patterns of stability and change in co-occurrence in children between 5–11 years, and to assess if they vary by socio-demographic factors. Methods Data from 9548 singleton children from the UK Millennium Cohort Study (MCS) were assessed for co-occurrence of five common adverse conditions: wheeze; longstanding illness; unfavorable weight; injury; and socio-emotional difficulties. We summed adverse conditions (0–5) for each child at ages 5, 7, and 11 and identified co-occurrence (≥2 conditions). Using multinomial regression, we explored associations between co-occurrence trajectories and child’s sex and ethnicity, maternal education, and income quintile. Results 45.6% of children experienced co-occurrence between 5–11 years (7% experienced constant co-occurrence). More children moved into co-occurrence than moved out (16.9 vs. 11.9%). Mutually-adjusted relative risk ratios (aRRR) showed a gradient by maternal education: compared to children with no co-occurrence whose mothers had a higher/degree, children whose mothers had no qualifications were more likely to move into (aRRR = 1.32(95%CI:1.02,1.70)), out of (1.74(1.34,2.26)), have fluctuating (1.52(1.09,2.10)) or constant co-occurrence (2.58(1.76,3.80)). The same gradient (high vs. low) was evident for income quintiles. Girls were less likely to experience co-occurrence. Conclusions Co-occurrence of adverse conditions is common during childhood, and trajectories are socially patterned. Child-focused care for lower-income children and boys early in life may prevent and reduce co-occurrence in later childhood. PMID:27281228

  6. Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar

    PubMed Central

    Dubrovinsky, Leonid; Dubrovinskaia, Natalia; Prakapenka, Vitali B; Abakumov, Artem M

    2012-01-01

    Since invention of the diamond anvil cell technique in the late 1950s for studying materials at extreme conditions, the maximum static pressure generated so far at room temperature was reported to be about 400 GPa. Here we show that use of micro-semi-balls made of nanodiamond as second-stage anvils in conventional diamond anvil cells drastically extends the achievable pressure range in static compression experiments to above 600 GPa. Micro-anvils (10–50 μm in diameter) of superhard nanodiamond (with a grain size below ∼50 nm) were synthesized in a large volume press using a newly developed technique. In our pilot experiments on rhenium and gold we have studied the equation of state of rhenium at pressures up to 640 GPa and demonstrated the feasibility and crucial necessity of the in situ ultra high-pressure measurements for accurate determination of material properties at extreme conditions. PMID:23093199

  7. High-pressure high-temperature phase diagram of gadolinium studied using a boron-doped heater anvil

    DOE PAGESBeta

    Montgomery, J. M.; Samudrala, G. K.; Velisavljevic, N.; Vohra, Y. K.

    2016-04-07

    A boron-doped designer heater anvil is used in conjunction with powder x-ray diffraction to collect structural information on a sample of quasi-hydrostatically loaded gadolinium metal up to pressures above 8GPa and 600K. The heater anvil consists of a natural diamond anvil that has been surface modified with a homoepitaxially grown chemical-vapor-deposited layer of conducting boron-doped diamond, and is used as a DC heating element. Internally insulating both diamond anvils with sapphire support seats allows for heating and cooling of the high-pressure area on the order of a few tens of seconds. This device is then used to scan the phasemore » diagram of the sample by oscillating the temperature while continuously increasing the externally applied pressure and collecting in situ time-resolved powder diffraction images. In the pressure-temperature range covered in this experiment, the gadolinium sample is observed in its hcp, αSm, and dhcp phases. Under this temperature cycling, the hcp → αSm transition proceeds in discontinuous steps at points along the expected phase boundary. From these measurements (representing only one hour of synchrotron x-ray collection time), a single-experiment equation of state and phase diagram of each phase of gadolinium is presented for the range of 0–10GPa and 300–650K« less

  8. High-pressure high-temperature phase diagram of gadolinium studied using a boron-doped heater anvil

    NASA Astrophysics Data System (ADS)

    Montgomery, J. M.; Samudrala, G. K.; Velisavljevic, N.; Vohra, Y. K.

    2016-04-01

    A boron-doped designer heater anvil is used in conjunction with powder x-ray diffraction to collect structural information on a sample of quasi-hydrostatically loaded gadolinium metal up to pressures above 8 GPa and 600 K. The heater anvil consists of a natural diamond anvil that has been surface modified with a homoepitaxially grown chemical-vapor-deposited layer of conducting boron-doped diamond, and is used as a DC heating element. Internally insulating both diamond anvils with sapphire support seats allows for heating and cooling of the high-pressure area on the order of a few tens of seconds. This device is then used to scan the phase diagram of the sample by oscillating the temperature while continuously increasing the externally applied pressure and collecting in situ time-resolved powder diffraction images. In the pressure-temperature range covered in this experiment, the gadolinium sample is observed in its hcp, αSm, and dhcp phases. Under this temperature cycling, the hcp → αSm transition proceeds in discontinuous steps at points along the expected phase boundary. From these measurements (representing only one hour of synchrotron x-ray collection time), a single-experiment equation of state and phase diagram of each phase of gadolinium is presented for the range of 0-10 GPa and 300-650 K.

  9. Characteristics of anvil-top associated with the Poplar Bluff tornado of 7 May 1973

    NASA Technical Reports Server (NTRS)

    Pearl, E. W.

    1973-01-01

    Investigation of potential tornado-producing thunderstorms was performed during part of the 1972 and 1973 tornado seasons. On May 7, 1973 twenty-one tornadoes were confirmed over southern Missouri, northern Arkansas, and southwestern Illinois. The region was surveyed by high altitude photography performed on a Learjet over the region of reported tornadoes. Two storms were chosen from aircraft observation with the guidance of ground and radar reports, and a series of photographs were taken of a tornado producing cloud. An analysis of the activity before and during the tornado is made, and most noteworthy were changes detected in the growth and collapse of overshooting domes above the anvil. Suggestions are included for a comprehensive study.

  10. Apparatus and Techniques for Time-resolved Synchrotron X-ray Diffraction using Diamond Anvil Cells

    NASA Astrophysics Data System (ADS)

    Smith, J.; Sinogeikin, S. V.; Lin, C.; Rod, E.; Bai, L.; Shen, G.

    2015-12-01

    Complementary advances in synchrotron sources, x-ray optics, area detectors, and sample environment control have recently made possible many time-resolved experimental techniques for studying materials at extreme pressure and temperature conditions. The High Pressure Collaborative Access Team (HPCAT) at the Advanced Photon Source has made a sustained effort to assemble a powerful collection of high-pressure apparatus for time-resolved research, and considerable time has been invested in developing techniques for collecting high-quality time-resolved x-ray scattering data. Herein we present key aspects of the synchrotron beamline and ancillary equipment, including source considerations, rapid (de)compression apparatus, high frequency imaging detectors, and software suitable for processing large volumes of data. A number of examples are presented, including fast equation of state measurements, compression rate dependent synthesis of metastable states in silicon and germanium, and ultrahigh compression rates using a piezoelectric driven diamond anvil cell.

  11. Characteristics of silicone fluid as a pressure transmitting medium in diamond anvil cells

    NASA Astrophysics Data System (ADS)

    Shen, Yongrong; Kumar, Ravhi S.; Pravica, Michael; Nicol, Malcolm F.

    2004-11-01

    The properties of a silicone fluid with initial viscosity of 1 cst as a pressure transmitting medium for diamond anvil cells have been determined by ruby R1 line broadening and R1-R2 separation measurements to 64 GPa at ambient temperature. By these criteria, the silicone fluid is as good a pressure medium as a 4:1 methanol:ethanol mixture at low pressures to about 20 GPa, and is better than the mixture at higher pressures. Although argon media are better than the silicone at pressures to 30 GPa, this silicone behaves as well as argon at higher pressures. Furthermore, the silicone is easier to load than argon and is almost chemically inert.

  12. The birth and development of laser heating in diamond anvil cells

    NASA Astrophysics Data System (ADS)

    Bassett, William A.

    2001-02-01

    In 1968 Taro Takahashi and I observed a phase transition that resulted from laser heating under pressure in a diamond anvil cell. Using a ruby laser, we successfully converted graphite to diamond. We soon realized that the ruby laser had such limited capabilities that we acquired a yttrium-aluminum-garnet (YAG) laser that could be used in both continuous and pulsed modes. The road to successfully applying the technique was not without a few bumps. Thirty years later, these seem more amusing than they did at the time. It was with the YAG laser that Ming and Liu investigated a number of silicate phase transitions important to our understanding of the earth's mantle. Since then it has been gratifying to watch as others have adopted the technique and made many important contributions with it.

  13. Density measurement of samples under high pressure using synchrotron microtomography and diamond anvil cell techniques

    PubMed Central

    Xiao, Xianghui; Liu, Haozhe; Wang, Luhong; De Carlo, Francesco

    2010-01-01

    Accurate mass density information is critical in high-pressure studies of materials. It is, however, very difficult to measure the mass densities of amorphous materials under high pressure with a diamond anvil cell (DAC). Employing tomography to measure mass density of amorphous samples under high pressure in a DAC has recently been reported. In reality, the tomography data of a sample in a DAC suffers from not only noise but also from the missing angle problem owing to the geometry of the DAC. An algorithm that can suppress noise and overcome the missing angle problem has been developed to obtain accurate mass density information from such ill-posed data. The validity of the proposed methods was supported with simulations. PMID:20400834

  14. Electrical conductivity measurements of aqueous fluids under pressure with a hydrothermal diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Ni, Huaiwei; Chen, Qi; Keppler, Hans

    2014-11-01

    Electrical conductivity data of aqueous fluids under pressure can be used to derive the dissociation constants of electrolytes, to assess the effect of ionic dissociation on mineral solubility, and to interpret magnetotelluric data of earth's interior where a free fluid phase is present. Due to limitation on the tensile strength of the alloy material of hydrothermal autoclaves, previous measurements of fluid conductivity were mostly restricted to less than 0.4 GPa and 800 °C. By adapting a Bassett-type hydrothermal diamond anvil cell, we have developed a new method for acquiring electrical conductivity of aqueous fluids under pressure. Our preliminary results for KCl solutions using the new method are consistent with literature data acquired with the conventional method, but the new method has great potential for working in a much broader pressure range.

  15. Studies of Mineral Properties at Mantle Condition using Deformation Multi-Anvil Apparatus

    SciTech Connect

    Li, L.

    2009-01-01

    This paper reports recent studies of the rheological and viscoelastic properties of minerals at mantle pressure and temperature using Deformation multi-anvil apparatus (D-DIA). Stress-strain-time relations were measured using synchrotron X-ray radiation to determine these properties. Rheological properties of San Carlos olivine were measured at pressure up to 10 GPa and indicated that the effect of pressure on the viscosity of olivine is much smaller than previous reported. The unique capability of synchrotron X-ray can resolve the stress heterogeneity within a polycrystalline material as well as within a multi-phase mixture and elucidate the stress-strain distribution in an aggregate. Anelasticity measurements were carried out using olivine as the sample at mantle pressure and temperatures. The results showed that grain boundary activity rather than pressure dominate the relaxation processes. The aim of this paper is to illustrate the methods using new tools for high pressure research.

  16. High-Temperature Experiments using a Resistively-Heated High-Pressure Membrane Diamond Anvil Cell

    SciTech Connect

    Jenei, Z; Visbeck, K; Cynn, H; Yoo, C; Evans, W

    2009-04-22

    A reliable high-performance heating method using resistive heaters and a membrane driven diamond anvil cell (mDAC) is presented. Two micro-heaters are mounted in a mDAC and use electrical power of less than 150 W to achieve sample temperatures up to 1200 K. For temperature measurement we use two K-type thermocouples mounted near the sample. The approach can be used for in-situ Raman spectroscopy and x-ray diffraction at high pressures and temperatures. A W-Re alloy gasket material permits stable operation of mDAC at high temperature. Using this method, we made an isothermal compression at 900 K to pressures in excess of 100 GPa and isobaric heating at 95 GPa to temperatures in excess of 1000 K. As an example, we present high temperature Raman spectroscopy measurements of nitrogen at high pressures.

  17. Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability

    NASA Astrophysics Data System (ADS)

    Palmer, A.; Silevitch, D. M.; Feng, Yejun; Wang, Yishu; Jaramillo, R.; Banerjee, A.; Ren, Y.; Rosenbaum, T. F.

    2015-09-01

    We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as those from insulator to metal.

  18. Resistance heating of Fe and W in diamond-anvil cells

    NASA Technical Reports Server (NTRS)

    Boehler, R.; Nicol, M.; Zha, C. S.; Johnson, M. L.

    1986-01-01

    A new method for internally heating a diamond-anvil cell is described. Fine wires of iron or tungsten are resistively heated in a gasketed cell, thus providing a uniformly distributed pressure that can be measured in situ by employing the ruby scale. Temperatures of several thousand degrees have been measured by fitting a black body radiation function to the spectrum of the hot wire taken with an optical multichannel analyzer. Temperatures as high as the melting temperature of tungsten have been achieved. The alpha-gamma and alpha-epsilon phase transitions of iron have been studied, and the results show excellent agreement with previous data obtained with piston-cylinder or externally-heated diamond cells.

  19. Raman spectroscopy study of nitromethane in a shear diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Hébert, Philippe; Isambert, Aude; Petitet, Jean-Pierre; Zerr, Andreas

    2010-03-01

    In addition to pressure and temperature effects, shear strain has been proposed to play an important role in the initiation and decomposition mechanisms of energetic materials. To study the effect of shear strain in more detail, a shear diamond anvil cell has been developed. In this paper, we present a Raman spectroscopy study of the effects of shear strain on the high-pressure behaviour of nitromethane (NM). Two major effects are observed in our experiments. The first one is a lowering of the pressures at which the different structural modifications of NM occur. The second one is observed at 28 GPa, where the sample decomposes suddenly just after shear application. Examination of the black residue showed that it is composed of carbon, as indicated by the Raman spectrum.

  20. Material transport in laser-heated diamond anvil cell melting experiments

    NASA Technical Reports Server (NTRS)

    Campbell, Andrew J.; Heinz, Dion L.; Davis, Andrew M.

    1992-01-01

    A previously undocumented effect in the laser-heated diamond anvil cell, namely, the transport of molten species through the sample chamber, over distances large compared to the laser beam diameter, is presented. This effect is exploited to determine the melting behavior of high-pressure silicate assemblages of olivine composition. At pressures where beta-spinel is the phase melted, relative strengths of partitioning can be estimated for the incompatible elements studied. Iron was found to partition into the melt from beta-spinel less strongly than calcium, and slightly more strongly than manganese. At higher pressures, where a silicate perovskite/magnesiowuestite assemblage is melted, it is determined that silicate perovskite is the liquidus phase, with iron-rich magnesiowuestite accumulating at the end of the laser-melted stripe.

  1. Summary of the oil shale fragmentation program at Anvil Points Mine, Colorado

    SciTech Connect

    Dick, R.D.; Young, C.; Fourney, W.L.

    1984-01-01

    During 1981 and 1982, an extensive oil shale fragmentation research program was conducted at the Anvil Points Mine near Rifle, Colorado. The primary goals were to investigate factors involved for adequate fragmentation of oil shale and to evaluate the feasibility of using the modified in situ retort (MIS) method for recovery of oil from oil shale. The test program included single-deck, single-borehole tests to obtain basic fragmentation data; multiple-borehole, multiple-deck explosive tests to evaluate practical aspects for developing an in situ retort; and the development of a variety of instrumentation techniques to diagnose the blasting event. This paper will present an outline of the field program, the type of instrumentation used, some typical results from the instrumentation, and a discussion of explosive engineering problems encountered over the course of the program. 4 references, 21 figures, 1 table.

  2. Explosive fragmentation of oil shale: Results from Colony and Anvil Points Mines, Colorado

    SciTech Connect

    Dick, R.D.; Fourney, W.L.; Young, C. III

    1992-12-31

    From 1978 through 1983, numerous oil shale fragmentation tests were conducted at the Colony and Anvil Points Mines, Colorado. These experiments were part of an investigation to determine factors required for the adequate fragmentation of oil shale and to evaluate the feasibility of using the vertical modified in situ retort (VMIS) method for recovery of kerogen from oil shale. The objective of this research was to support the design of a large volume (10{sup 4} m{sup 3}) rubble bed for in situ processing. In addition, this rubble bed was to be formed in a large single-blast event which included decked charges, time delays, and multiple boreholes. Results are described.

  3. Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability.

    PubMed

    Palmer, A; Silevitch, D M; Feng, Yejun; Wang, Yishu; Jaramillo, R; Banerjee, A; Ren, Y; Rosenbaum, T F

    2015-09-01

    We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as those from insulator to metal. PMID:26429451

  4. Ultrahigh-pressure experiment with a motor-driven diamond anvil cell.

    PubMed

    Mao, Wendy L; Mao, Ho-Kwang

    2006-06-28

    A Pt sample was compressed to ultrahigh pressures in a diamond anvil cell (DAC) using a motorized gearbox to change pressure remotely from outside the synchrotron x-ray hutch. In situ angle-dispersive x-ray diffraction (XRD) was used to determine pressure from known equations of state (EOS). The sample position was unperturbed during motor-driven pressure changes. By eliminating the need to realign the sample to the x-ray position after each pressure increment, 142 XRD patterns could be collected continuously over the course of three hours, and the maximum pressure of 230 GPa was reached before diamond failure ended the experiment. We demonstrate the advantages of this motor-driven assembly for smooth and efficient pressure change, and the possibility for fine pressure and temporal resolution. PMID:22611097

  5. High pressure Moissanite-anvil cells for the low temperature Hall effect measurements of oxide superconductors

    NASA Astrophysics Data System (ADS)

    Yomo, Shusuke; Tozer, Stanley

    2013-03-01

    The Hall effect was successfully measured for a single crystal of high temperature superconductor in a Moissanite-anvil clamp cell up to 5 GPa, with proper arrangement of lead wires and a sample. Zylon gasket, good in electrical insulation, worked well up to 5 GPa. The 30-40 % increase of the clamped pressure was observed during cooling to below 60 K. The appreciable pressure effect of the a-b plane Hall coefficient was observed and negative for La2 - x Srx CuO4 with x = 0.090. The result is discussed with those for sintered samples and those studied with a different pressurizing method. Thanks are due to Visiting Scientist Program, NHMFL, and NNSA grant DE-FG52-03NA00066.

  6. Tuning surface plasmon resonance by the plastic deformation of Au nanoparticles within a diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Bao, Yongjun; Zhao, Bin; Tang, Xinyu; Hou, Dongjie; Cai, Jian; Tang, Shan; Liu, Junsong; Wang, Fei; Cui, Tian

    2015-11-01

    In this work, surface plasmon resonance (SPR) is tuned by controlling the deformation of Au nanoparticles within a diamond anvil cell (DAC). Colloidal Au nanoparticles were loaded into a DAC and pressurized into a mixture of ice and Au nanoparticles. The Au nanoparticles were reshaped by their anisotropic compression of surrounding ice, which leads to the spectral variations of absorption peaks, broadening or red-shifting. These spectral features are well tuned by controlling the deformation process of Au nanoparticle with choosing the initial intended thickness of DAC gasket. The mechanical properties of Au nanoparticles are also revealed by the shape-dependent SPR in nanometer scale. This result provides us a way to fabricate Au nanoparticles into new shapes and tune SPR of metallic nanoparticles with pressure.

  7. Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in situ tunability

    SciTech Connect

    Palmer, A; Silevitch, D M; Feng, Yejun; Wang, Y; Jaramillo, R.; Banerjee, A.; Ren, Y.; Rosenbaum, T. F.

    2015-09-01

    We discuss techniques for performing continuous measurements across a wide range of pressure–field–temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as those from insulator to metal.

  8. Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell

    SciTech Connect

    Armstrong, M; Crowhurst, J; Reed, E; Zaug, J

    2008-02-04

    We have used sub-picosecond laser pulses to launch ultra-high strain rate ({approx} 10{sup 9} s{sup -1}) nonlinear acoustic waves into a 4:1 methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which may result in shock wave behavior. We compare our results with low strain, low strain-rate acoustic data. This technique provides controlled access to regions of thermodynamic phase space that are otherwise difficult to obtain.

  9. High-pressure high temperature generation over 40 GPa using Kwai-type multianvil apparatus with carbide anvils

    NASA Astrophysics Data System (ADS)

    Ishii, T.; Shi, L.; Miyajima, N.; Boffa Ballaran, T.; Sinmyo, R.; Kawazoe, T.; Katsura, T.

    2015-12-01

    Kawai-type multianvil apparatus are widely used as high-pressure devices to generate pressures to the uppermost lower mantle using tungsten carbide (WC) anvils. Combination with sintered diamond (SD) anvils allows generating pressure above 30 to usually 60 GPa. However, it is difficult to use SD anvils practically, because they are much expensive than WC anvils. We therefore developed experimental techniques to generate pressures over 40 GPa using a Kawai-type apparatus with WC anvils particularly for studying phase relations in multi-component systems in the lower mantle down to 1000 km depth. We used a 15-MN Kawai-type multianvil apparatus with DIA-type guide blocks with careful optimization of a cubic compression space formed by first-stage anvils. Pressures were generated using hard WC anvils (TF05, Fujilloy Co., Ltd) with truncation of 1.5 mm and taper of 1.0ᴼ with a semi-sintered MgO + 5wt.%Cr2O3 octahedron as a pressure medium. Pressure was calibrated by detecting resistance changes of Bi, ZnS, GaP and Zr at room temperature. The maximum achievable pressure at 2000 K, which was generated using a Re heater in a LaCrO3 thermal insulator, was examined by the Al2O3 content in aluminous bridgemanite. Al2O3 rods were placed at the both side of the sample in a furnace. The starting material was sintered ilmenite-type Mg3Al2Si3O12 synthesized at 1200 K and 26 GPa (Kubo and Akaogi, 2000). We observed the ω-β transition in Zr (34 GPa) (Ono and Kikegawa, 2015) at a press load of 8 MN at room temperature. The sample synthesized at 2000 K and 15 MN has a composition nearly equal to pyrope and the LiNbO3-type structure. The LiNbO3 structure of the recovered sample with pyrope composition suggests that it had the perovskite structure before recovery. The composition of this sample suggests generation of 44 GPa at a high temperature of 2000 K, according to the phase relations in the MgSiO3-Al2O3 system (Liu, private communication).

  10. Aqueous Chemistry in the Diamond Anvil Cell up to and Beyond the Critical Point of Water

    SciTech Connect

    Bassett, William A.; Chou, I-Ming; Anderson, Alan J.; Mayanovic, Robert

    2008-08-28

    The hydrothermal diamond anvil cell (HDAC) has been developed for the study of fluids and their interactions with other phases. It is capable of pressures up to 10 GPa and temperatures from -190 C to 1200 C. It has found application in studies of equations of state of fluids, reactions between fluids and solids as well as fluids and melts, hydration and dehydration of hydrous solids under P{sub H2O}, fractionation of species between fluids and solids as well as fluids and melts, the effect of P{sub H2O} on melting of silicates, structures of ions and clathrates in solution, preservation of hosts of fluid inclusions at high temperatures, and reactions in clathrates and other organic materials. Visual, spectroscopic, and X-ray methods are used to analyze samples by taking advantage of the exceptional transparency of the diamond anvils. Examples of successful apphcations of the HDAC include the equation of state (EOS) of water, stability of the various stages of hydration of montmorillonite and calcium carbonate, leaching of elements from zircon, the effect of P{sub H2O} on the melting of albite, speciation and structures of Sc, Fe, Cu, Zn, Y, La, Yb, and Br in solution, stability of methane hydrates and Ca(OH){sub 2}, identifying a new H{sub 2}O ice form and sll of methane hydrate. The description of diamond cell configuration, analytical methods, and examples of applications provide evidence of the utility of the technique for many studies of fluids at temperatures and pressures up to and beyond the critical point of water.

  11. Detection and validation of a small broad-host-range plasmid pBBR1MCS-2 for use in genetic manipulation of the extremely acidophilic Acidithiobacillus sp.

    PubMed

    Hao, Likai; Liu, Xiangmei; Wang, Huiyan; Lin, Jianqun; Pang, Xin; Lin, Jianqiang

    2012-09-01

    An efficient genetic system for introducing genes into biomining microorganisms is essential not only to experimentally determine the functions of genes predicted based on bioinformatic analysis, but also for their genetic breeding. In this study, a small broad-host-range vector named pBBR1MCS-2, which does not belong to the IncQ, IncW, or IncP groups, was studied for the feasibility of its use in conjugative gene transfer into extremely acidophilic strains of Acidithiobacillus. To do this, a recombinant plasmid pBBR-tac-Sm, a derivative of pBBR1MCS-2, was constructed and the streptomycin resistant gene (Sm(r)) was used as the reporter gene. Using conjugation, pBBR-tac-Sm was successfully transferred into three tested strains of Acidithiobacillus. Then we measured its transfer frequency, its stability in Acidithiobacillus cells, and the level of resistance to streptomycin of the transconjugants and compared this with the IncQ plasmid pJRD215 control. Our results indicate that pBBR1MCS-2 provides a new and useful tool in the genetic manipulation of Acidithiobacillus strains. PMID:22705922

  12. Numerical and Observational Investigations of Long-Lived Mcs-Induced Severe Surface Wind Events: the Derecho

    NASA Astrophysics Data System (ADS)

    Schmidt, Jerome Michael

    This study addresses the production of sustained, straight-line, severe surface winds associated with mesoscale convective systems (MCSs) of extratropical origin otherwise known as derechos. The physical processes which govern the observed derecho characteristics are identified and their possible forcing mechanisms are determined. Detailed observations of two derechos are presented along with simulations using the Colorado State University Regional Atmospheric Modeling System (CSU-RAMS). The observations revealed a derecho environment characterized by strong vertical wind shear through the depth of the troposphere and large values of convective available potential energy (CAPE). The thermodynamic environment of the troposphere in each case had a distinct three-layer structure consisting of: (i) a surface-based stable layer of 1-to-2 km in depth, (ii) an elevated well -mixed layer of 2-4 km in depth, and (iii) an upper tropospheric layer of intermediate stability that extended to the tropopause. Two primary sets of simulations were performed to assess the impact of the observed environmental profiles on the derecho structure, propagation, and longevity. The first set consisted of nested-grid regional-scale simulations initialized from the standard NMC analyses on a domain having relatively coarse horizontal resolution (75 km). The second set of simulations consisted of two and three-dimensional experiments initialized in a horizontally homogeneous environment having a relatively fine horizontal resolution (2 km) and explicit microphysics. The results from these experiments indicate the importance of convectively -induced gravity waves on the MCS structure, propagation, longevity, and severe surface wind development. The sensitivity of the simulated convection and gravity waves to variations in the vertical wind shear and moisture profiles are described. Detailed Doppler radar analyses and 3-D simulations of a severe, bow echo squall line are presented which reveal

  13. The implications of non-linear biological oscillations on human electrophysiology for electrohypersensitivity (EHS) and multiple chemical sensitivity (MCS).

    PubMed

    Sage, Cindy

    2015-01-01

    maintenance; and resilience can be compromised. Electrohypersensitivity can be caused by successive assaults on human bioelectrochemical dynamics from exogenous electromagnetic fields (EMF) and RFR or a single acute exposure. Once sensitized, further exposures are widely reported to cause reactivity to lower and lower intensities of EMF/RFR, at which point thousand-fold lower levels can cause adverse health impacts to the electrosensitive person. Electrohypersensitivity (EHS) can be a precursor to, or linked with, multiple chemical sensitivity (MCS) based on reports of individuals who first develop one condition, then rapidly develop the other. Similarity of chemical biomarkers is seen in both conditions [histamines, markers of oxidative stress, auto-antibodies, heat shock protein (HSP), melatonin markers and leakage of the blood-brain barrier]. Low intensity pulsed microwave activation of voltage-gated calcium channels (VGCCs) is postulated as a mechanism of action for non-thermal health effects. PMID:26368042

  14. The relation of the yield stress of high-pressure anvils to the pressure attained at yielding and the ultimate attainable pressure

    NASA Technical Reports Server (NTRS)

    Panda, P. C.; Ruoff, A. L.

    1979-01-01

    A sensitive microprofilometer was used to determine the onset of yielding in the anvils of a supported opposed anvil device for the case of 3% cobalt-cemented tungsten carbide as the anvil material. In addition, it is shown how the commencement of yielding in boron carbide pistons, the yield strength being known, can be used to obtain the transition pressure to a conducting phase in gallium phosphide. The transition pressures of bismuth and gallium phosphide are obtained and it is found that these transitions are extremely close to the maximum attainable pressure in, respectively, a maraging steel and a 3% cobalt-cemented tungsten carbide.

  15. Multi-Anvil Techniques in Conjunction With Synchrotron Radiation - MAX80 and MAX200x

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Schilling, F. R.; Lathe, C.

    2005-12-01

    During the early 80's of the last century geoscientists worldwide realized synchrotron radiation as a highly valuable tool for in situ experiments, i.e. experiments under simulated Earth's mantle conditions. MAX80 at HASYLAB, Hamburg, a single-stage multi-anvil DIA-system at a synchrotron beamline was among the high-pressure pioneer apparatus designed in Japan. Meantime it is equipped for all kinds of ultrasonic interferometry in conjunction with synchrotron radiation measurements, i.e. XRD and X-radiography. The maximum conditions are about 10 GPa / 2000 K. To make transition zone conditions accessible and to achieve bigger specimen volumes the sister apparatus MAX200x, a double-stage DIA-system, was installed at the HASYLAB HARWI-II beamline recently. The newly designed high-flux hard wiggler is an optimum X-ray source for this kind of experiments. MAX2000x is designed to reach 25 GPa and 2400 K, simultaneously. MAX200x is driven by a hydraulic ram with a maximum load of 1750 tons. This press is mounted on a y-z-table to adjust the sample to the synchrotron beam. Furthermore, the press can be rotated to enhance statistics during the diffraction experiments. The whole system weights about 30 tons. Derived from the successful equipment of MAX80 and adapted to the new task MAX200x is equipped for XRD with a Ge-solid-state detector, for transient ultrasonic interferometry, as well as with a radiography system to measure the change of volume and shape of the sample under in situ conditions. A stepper motor driven slits system allows to optimize X-ray beam size and shape for the experiments. The whole system is remote controlled. The goniometer will be mounted on a moveable table. Both, experiments with monochromatic and white X-rays will be available. Besides Ge-solid state detector new designed goniometers will be used to enhance the precision of the experiments. Parallel to the installation of MAX200x some innovative experiments were carried out to improve the

  16. Black African Traditional Mathematics

    ERIC Educational Resources Information Center

    Zaslavsky, Claudia

    1970-01-01

    Discusses the traditional number systems and the origin of the number names used by several African peoples living south of the Sahara. Also included are limitations in African mathematical development, and possible topics for research. (RP)

  17. Multi-anvil High Pressure Facility at National Synchrotron Light Source: Then, Now, and Future

    NASA Astrophysics Data System (ADS)

    Wang, L.; Weidner, D. J.; Vaughan, M. T.; Chen, J.; Li, B.; Liebermann, R. C.

    2007-12-01

    Multi-anvil high pressure facility (Beamline X17B2) at National Synchrotron Light Source (NSLS) was the first of its kind established in the United States with the support from NSF through the Center for High Pressure Research (CHiPR, 1990 - 2002). During this period, the facility provided a fertile ground for steep growth of research on earth materials at simultaneously high pressures and temperatures. Main areas of study included the thermoelastic and structural properties of minerals, phase equilibria, rheology, acoustic velocities, kinetics of phase transformations, and physical properties of melts. The rheological and acoustic measurements at high pressures in conjunction with synchrotron were first developed at this facility, and both techniques are being adapted today by other laboratories around the world. Last five years has witnessed great increases in efficiency and productivity of this facility, a beneficiary of the construction of a permanent hutch and time-sharing mechanism made possible by NSLS, and the establishment of the Consortium for Materials Properties Research in Earth Sciences (COMPRES). While other above- mentioned areas of research continued to grow, the rheological studies of minerals experienced fast expansion through the use of two new high pressure deformation apparatus, the Deformation DIA (D-DIA) and the Rotational Drickamer apparatus (RDA, led by S. Karato from Yale Univ.) Experiments are currently being performed on various mantle minerals to derive their rheological properties. Performance of the facility will receive another boost through the addition of a monochromatic side station jointly supported by DoD, COMPRES and NSLS, and construction of the station is well underway. With continued operation of COMPRES in next five years, we will see several significant additions to the large- volume facility at NSLS: a new system for precise measurements of stress at high pressure; a 2000-ton press; D- TCup apparatus for deformation

  18. The African Connection

    ERIC Educational Resources Information Center

    Oguntoyinbo, Lekan

    2012-01-01

    From student and faculty exchanges to joint research projects, U.S. universities maintain a broad spectrum of collaborative relationships with African universities. It's unclear how many U.S. colleges and universities have partnerships with African universities. The African Studies Association, an organization of scholars, doesn't keep that kind…

  19. A confocal set-up for micro-XRF and XAFS experiments using diamond-anvil cells.

    PubMed

    Wilke, Max; Appel, Karen; Vincze, Laszlo; Schmidt, Christian; Borchert, Manuela; Pascarelli, Sakura

    2010-09-01

    A confocal set-up is presented that improves micro-XRF and XAFS experiments with high-pressure diamond-anvil cells (DACs). In this experiment a probing volume is defined by the focus of the incoming synchrotron radiation beam and that of a polycapillary X-ray half-lens with a very long working distance, which is placed in front of the fluorescence detector. This set-up enhances the quality of the fluorescence and XAFS spectra, and thus the sensitivity for detecting elements at low concentrations. It efficiently suppresses signal from outside the sample chamber, which stems from elastic and inelastic scattering of the incoming beam by the diamond anvils as well as from excitation of fluorescence from the body of the DAC. PMID:20724788

  20. Hydrothermal diamond anvil cell for XAFS studies of first-row transition elements in aqueous solutions up to supercritical conditions

    USGS Publications Warehouse

    Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Chou, I.-Ming

    2000-01-01

    A hydrothermal diamond anvil cell (HDAC) has been modified by drilling holes with a laser to within 150 ??m of the anvil face to minimize the loss of X-rays due to absorption and scatter by diamond. This modification enables acquisition of K-edge X-ray absorption fine structure (XAFS) spectra from first-row transition metal ions in aqueous solutions at temperatures ranging from 25??C to 660??C and pressures up to 800 MPa. These pressure-temperature (P-T) conditions are more than sufficient for carrying out experimental measurements that can provide data valuable in the interpretation of fluid inclusions in minerals found in ore-forming hydrothermal systems as well as other important lithospheric processes involving water. (C) 2000 Elsevier Science B.V. All rights reserved.

  1. Microfabrication of controlled-geometry samples for the laser-heated diamond-anvil cell using focused ion beam technology

    SciTech Connect

    Pigott, Jeffrey S.; Reaman, Daniel M.; Panero, Wendy R.

    2012-02-06

    The pioneering of x-ray diffraction with in situ laser heating in the diamond-anvil cell has revolutionized the field of high-pressure mineral physics, expanding the ability to determine high-pressure, high-temperature phase boundaries and equations of state. Accurate determination of high-pressure, high-temperature phases and densities in the diamond-anvil cell rely upon collinearity of the x-ray beam with the center of the laser-heated spot. We present the development of microfabricated samples that, by nature of their design, will have the sample of interest in the hottest portion of the sample. We report initial successes with a simplified design using a Pt sample with dimensions smaller than the synchrotron-based x-ray spot such that it is the only part of the sample that absorbs the heating laser ensuring that the x-rayed volume is at the peak hotspot temperature. Microfabricated samples, synthesized using methods developed at The Ohio State University's Mineral Physics Laboratory and Campus Electron Optics Facility, were tested at high P-T conditions in the laser-heated diamond-anvil cell at beamline 16 ID-B of the Advanced Photon Source. Pt layer thicknesses of {le} 0.8 {micro}m absorb the laser and produce accurate measurements on the relative equations of state of Pt and PtC. These methods combined with high-purity nanofabrication techniques will allow for extension by the diamond-anvil cell community to multiple materials for high-precision high-pressure, high-temperature phase relations, equations of state, melting curves, and transport properties.

  2. The Non-coding Mammary Carcinoma Susceptibility Locus, Mcs5c, Regulates Pappa Expression via Age-Specific Chromatin Folding and Allele-Dependent DNA Methylation

    PubMed Central

    Henning, Amanda N.; Haag, Jill D.; Smits, Bart M. G.; Gould, Michael N.

    2016-01-01

    In understanding the etiology of breast cancer, the contributions of both genetic and environmental risk factors are further complicated by the impact of breast developmental stage. Specifically, the time period ranging from childhood to young adulthood represents a critical developmental window in a woman’s life when she is more susceptible to environmental hazards that may affect future breast cancer risk. Although the effects of environmental exposures during particular developmental Windows of Susceptibility (WOS) are well documented, the genetic mechanisms governing these interactions are largely unknown. Functional characterization of the Mammary Carcinoma Susceptibility 5c, Mcs5c, congenic rat model of breast cancer at various stages of mammary gland development was conducted to gain insight into the interplay between genetic risk factors and WOS. Using quantitative real-time PCR, chromosome conformation capture, and bisulfite pyrosequencing we have found that Mcs5c acts within the mammary gland to regulate expression of the neighboring gene Pappa during a critical mammary developmental time period in the rat, corresponding to the human young adult WOS. Pappa has been shown to positively regulate the IGF signaling pathway, which is required for proper mammary gland/breast development and is of increasing interest in breast cancer pathogenesis. Mcs5c-mediated regulation of Pappa appears to occur through age-dependent and mammary gland-specific chromatin looping, as well as genotype-dependent CpG island shore methylation. This represents, to our knowledge, the first insight into cellular mechanisms underlying the WOS phenomenon and demonstrates the influence developmental stage can have on risk locus functionality. Additionally, this work represents a novel model for further investigation into how environmental factors, together with genetic factors, modulate breast cancer risk in the context of breast developmental stage. PMID:27537370

  3. Prospective randomised comparison of the COBE spectra version 6 and haemonetics MCS(+) cell separators for hematopoietic progenitor cells leucapheresis in patients with multiple myeloma.

    PubMed

    Abdelkefi, A; Maamar, M; Torjman, L; Ladeb, S; Lakhal, A; Ben Othman, T; Slama, H; Jenhani, F; Mojaat, N; Ben Hamed, L; Bouhoula, S; Hsairi, M; Boukef, K; Ben Abdeladhim, A

    2006-07-01

    A randomised crossover trial of two separators was undertaken to compare the mononuclear cell, CD34(+) cell and CFU-GM yield, in patients (<61 years) with previously untreated symptomatic multiple myeloma. After first-line therapy, all patients received mobilising chemotherapy (cyclophosphamide 4 g/m(2)) and daily G-CSF. The first leucapheresis was performed on the first day the peripheral blood absolute CD34(+) cell count was > 20 cells/microl. All patients underwent 2 leucaphereses on consecutive days. The patients were randomised to undergo either the first or second leucapheresis using the COBE Spectra. The target duration of the procedure on the COBE Spectra was 2 total blood volumes, and for the Haemonetics MCS(+) it was 20 cycles with four recirculations. Between September 2003 and March 2005, 60 patients were entered in the study. COBE Spectra version 6 processed significantly larger volumes of blood than the Haemonetics MCS(+) (8,845 and 5,680 ml, respectively, P < 0.01). The absolute yield of mononuclear cells (2.1 vs. 1.5 x 10(8)/kg, P = 0.04), CFU-GM (11 vs. 3 x 10(4)/kg, P = 0.01) and CD34(+) cells (3 vs. 1.7 x 10(6)/kg, P = 0.02) were all significantly higher with the COBE Spectra version 6, as were the yields per unit volume of blood processed. In conclusion, our study shows that COBE Spectra Version 6 is faster and has a better yield than the Haemonetics MCS(+), in patients with multiple myeloma. PMID:16395725

  4. The Non-coding Mammary Carcinoma Susceptibility Locus, Mcs5c, Regulates Pappa Expression via Age-Specific Chromatin Folding and Allele-Dependent DNA Methylation.

    PubMed

    Henning, Amanda N; Haag, Jill D; Smits, Bart M G; Gould, Michael N

    2016-08-01

    In understanding the etiology of breast cancer, the contributions of both genetic and environmental risk factors are further complicated by the impact of breast developmental stage. Specifically, the time period ranging from childhood to young adulthood represents a critical developmental window in a woman's life when she is more susceptible to environmental hazards that may affect future breast cancer risk. Although the effects of environmental exposures during particular developmental Windows of Susceptibility (WOS) are well documented, the genetic mechanisms governing these interactions are largely unknown. Functional characterization of the Mammary Carcinoma Susceptibility 5c, Mcs5c, congenic rat model of breast cancer at various stages of mammary gland development was conducted to gain insight into the interplay between genetic risk factors and WOS. Using quantitative real-time PCR, chromosome conformation capture, and bisulfite pyrosequencing we have found that Mcs5c acts within the mammary gland to regulate expression of the neighboring gene Pappa during a critical mammary developmental time period in the rat, corresponding to the human young adult WOS. Pappa has been shown to positively regulate the IGF signaling pathway, which is required for proper mammary gland/breast development and is of increasing interest in breast cancer pathogenesis. Mcs5c-mediated regulation of Pappa appears to occur through age-dependent and mammary gland-specific chromatin looping, as well as genotype-dependent CpG island shore methylation. This represents, to our knowledge, the first insight into cellular mechanisms underlying the WOS phenomenon and demonstrates the influence developmental stage can have on risk locus functionality. Additionally, this work represents a novel model for further investigation into how environmental factors, together with genetic factors, modulate breast cancer risk in the context of breast developmental stage. PMID:27537370

  5. Anvil Glaciation in a Deep Cumulus Updraught over Florida Simulated with the Explicit Microphysics Model. I: Impact of Various Nucleation Processes

    NASA Technical Reports Server (NTRS)

    Phillips, Vaughan T. J.; Andronache, Constantin; Sherwood, Steven C.; Bansemer, Aaron; Conant, William C.; Demott, Paul J.; Flagan, Richard C.; Heymsfield, Andy; Jonsson, Haflidi; Poellot, Micheal; Rissman, Tracey A.; Seinfeld, John H.; Vanreken, Tim; Varutbangkul, Varuntida; Wilson, James C.

    2005-01-01

    Simulations of a cumulonimbus cloud observed in the Cirrus regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) with an advanced version of the Explicit Microphysics Model (EMM) are presented. The EMM has size-resolved aerosols and predicts the time evolution of sizes, bulk densities and axial ratios of ice particles. Observations by multiple aircraft in the troposphere provide inputs to the model, including observations of the ice nuclei and of the entire size distribution of condensation nuclei. Homogeneous droplet freezing is found to be the source of almost all of the ice crystals in the anvil updraught of this particular model cloud. Most of the simulated droplets that freeze to form anvil crystals appear to be nucleated by activation of aerosols far above cloud base in the interior of the cloud ("secondary" or "in cloud" droplet nucleation). This is partly because primary droplets formed at cloud base are invariably depleted by accretion before they can reach the anvil base in the updraught, which promotes an increase with height of the average supersaturation in the updraught aloft. More than half of these aerosols, activated far above cloud base, are entrained into the updraught of this model cloud from the lateral environment above about 5 km above mean sea level. This confirms the importance of remote sources of atmospheric aerosol for anvil glaciation. Other nucleation processes impinge indirectly upon the anvil glaciation by modifying the concentration of supercooled droplets in the upper levels of the mixed-phase region. For instance, the warm-rain process produces a massive indirect impact on the anvil crystal concentration, because it determines the mass of precipitation forming in the updraught. It competes with homogeneous freezing as a sink for cloud droplets. The effects from turbulent enhancement of the warm-rain process and from the nucleation processes on the anvil ice properties are assessed.

  6. An in situ approach to study trace element partitioning in the laser heated diamond anvil cell

    SciTech Connect

    Petitgirard, S.; Mezouar, M.; Borchert, M.; Appel, K.; Liermann, H.-P.; Andrault, D.

    2012-01-15

    Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample melting based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth.

  7. Online remote control systems for static and dynamic compression and decompression using diamond anvil cells

    SciTech Connect

    Sinogeikin, Stanislav V. Smith, Jesse S.; Rod, Eric; Lin, Chuanlong; Kenney-Benson, Curtis; Shen, Guoyin

    2015-07-15

    The ability to remotely control pressure in diamond anvil cells (DACs) in accurate and consistent manner at room temperature, as well as at cryogenic and elevated temperatures, is crucial for effective and reliable operation of a high-pressure synchrotron facility such as High Pressure Collaborative Access Team (HPCAT). Over the last several years, a considerable effort has been made to develop instrumentation for remote and automated pressure control in DACs during synchrotron experiments. We have designed and implemented an array of modular pneumatic (double-diaphragm), mechanical (gearboxes), and piezoelectric devices and their combinations for controlling pressure and compression/decompression rate at various temperature conditions from 4 K in cryostats to several thousand Kelvin in laser-heated DACs. Because HPCAT is a user facility and diamond cells for user experiments are typically provided by users, our development effort has been focused on creating different loading mechanisms and frames for a variety of existing and commonly used diamond cells rather than designing specialized or dedicated diamond cells with various drives. In this paper, we review the available instrumentation for remote static and dynamic pressure control in DACs and show some examples of their applications to high pressure research.

  8. Microphysical characteristics of aging anvils and cirrus sampled during TWP- ICE

    NASA Astrophysics Data System (ADS)

    McFarquhar, G.; Freer, M.; Um, J.; Mace, G.; Kok, G.; McCoy, R.; Tooman, T.

    2006-12-01

    Observations of anvils at various stages in their life cycle and in generic cirrus were made during the 2006 Tropical Warm Pool International Cloud Experiment (TWP-ICE) using the Atmospheric Radiation Measurement Program's Uninhabited Aerospace Vehicle's (ARM UAV) payload of in-situ cloud microphysics probes on the Scaled Composites Proteus. The probes, including the Cloud and Aerosol Precipitation Spectrometer (CAPS), the Cloud Droplet Probe (CDP), the Cloud Particle Imager (CPI), the Cloud Spectrometer and Impactor Probe (CSI) and the Cloud Integrating Nephelometer (CIN), give number concentrations as a function of size, bulk parameters such as total water content and extinction, and information on ice crystal habits. Bulk measurements of total water content are also derived from co-located remote sensing measurements which are compared against the in-situ mass contents. In this presentation, data from the composite of probes are examined in an effort to determine the importance of ice crystals with maximum dimensions less than 100 micrometers to the total number, extinction and mass of the cirrus with varying ages. The variation of dominant ice crystal habit, median mass diameter and other bulk microphysical quantities with cirrus age and origin are also investigated. Implications of these results for cloud modeling studies are discussed.

  9. Diamond-anvil high-pressure cell with improved x-ray collimation system

    DOEpatents

    Schiferl, D.; Olinger, B.W.; Livingston, R.W.

    1984-03-30

    An adjustable x-ray collimation system for a diamond-anvil high-pressure cell of the type including a cooperable piston and cylinder and a pair of opposing diamonds located between the head of the piston and the head of the cylinder. The x-ray collimation system includes a tubular insert which contains an x-ray collimator. The insert is engageable in the bore of the piston. The collimator is mounted within the insert by means of an elastomeric o-ring at the end closest the opposed diamonds, and by means of a set of adjustable set screws at the opposite end. By adjustment of the set screws the collimator can be pivoted about the o-ring and brought into alignment with the opposed diamonds and the sample contained therein. In the preferred embodiment there is further provided a set of plugs which are insertable in the bore of the collimator. The plugs have bores of different diameters. By successively inserting plugs of progressively smaller bore diameters and adjusting the alignment of the collimator with each plug, the collimator can be quickly brought into accurate alignment with the diamonds. The collimation system allows alignment of the collimator either before or after the cell has been loaded and pressurized.

  10. Diamond-anvil high-pressure cell with improved X-ray collimation system

    DOEpatents

    Schiferl, David; Olinger, Barton W.; Livingston, Robert W.

    1986-01-01

    An adjustable X-ray collimation system for a diamond-anvil high-pressure cell of the type including a cooperable piston and cylinder and a pair of opposing diamonds located between the head of the piston and the head of the cylinder. The X-ray collimation system includes a tubular insert which contains an X-ray collimator. The insert is engageable in the bore of the piston. The collimator is mounted within the insert by means of an elastomeric O-ring at the end closest the opposed diamonds, and by means of a set of adjustable set screws at the opposite end. By adjustment of the set screws the collimator can be pivoted about the O-ring and brought into alignment with the opposed diamonds and the sample contained therein. In the preferred embodiment there is further provided a set of plugs which are insertable in the bore of the collimator. The plugs have bores of different diameters. By successively inserting plugs of progressively smaller bore diameters and adjusting the alignment of the collimator with each plug, the collimator can be quickly brought into accurate alignment with the diamonds. The collimation system allows alignment of the collimator either before or after the cell has been loaded and pressurized.

  11. Pressure-volume-temperature paths in the laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Kavner, Abby; Duffy, Thomas S.

    2001-02-01

    The temperature, pressure, and stress conditions in the diamond anvil cell sample chamber before, during, and after laser heating are mapped by employing standard materials as in situ pressure markers. Unit cell volumes of Pt, MgO, and NaCl were monitored by synchrotron-based x-ray diffraction at temperatures between 300 and 2290 K and pressures ranging from 14 to 53 GPa. To aid in interpreting the resulting pressure-volume-temperature paths, we perform a series of model calculations of the high-temperature, high-pressure x-ray diffraction behavior of platinum subjected to a general stress state. Thermal pressure and thermal expansion effects within the laser-heated volume are observed but are not sufficient to fully explain the measured paths. Large apparent pressure changes can also result from relaxation of deviatoric stresses during heating and partial reintroduction of those stresses during quench. Deviatoric stresses, monitored from both diffraction peak widths and lattice parameter shifts as a function of (hkl), may significantly distort equation of state results if it is assumed that the sample is under hydrostatic pressure. Large-scale, nearly isothermal pressure relaxation events are observed at ˜2000 K. It is proposed that these arise from relaxation of heated components (pressure medium, gasket, cell itself) outside of the directly laser-heated volume.

  12. Hydrothermal diamond-anvil cell: Application to studies of geologic fluids

    USGS Publications Warehouse

    Chou, I.-Ming

    2003-01-01

    The hydrothermal diamond-anvil cell (HDAC) was designed to simulate the geologic conditions of crustal processes in the presence of water or other fluids. The HDAC has been used to apply external pressure to both synthetic and natural fluid inclusions in quartz to minimize problems caused by stretching or decrepitation of inclusions during microthermometric analysis. When the HDAC is loaded with a fluid sample, it can be considered as a large synthetic fluid inclusion and therefore, can be used to study the PVTX properties as well as phase relations of the sample fluid. Because the HDAC has a wide measurement pressure-temperature range and also allows in-situ optical observations, it has been used to study critical phenomena of various chemical systems, such as the geologically important hydrous silicate melts. It is possible, when the HDAC is combined with synchrotron X-ray sources, to obtain basic information on speciation and structure of metal including rare-earth elements (REE) complexes in hydrothermal solutions as revealed by X-ray absorption fine structure (XAFS) spectra. Recent modifications of the HDAC minimize the loss of intensity of X-rays due to scattering and absorption by the diamonds. These modifications are especially important for studying elements with absorption edges below 10 keV and therefore particularly valuable for our understanding of transport and deposition of first-row transition elements and REE in hydrothermal environments.

  13. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    SciTech Connect

    Meier, Thomas; Haase, Jürgen

    2015-12-15

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al{sub 2}O{sub 3}), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  14. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa.

    PubMed

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures. PMID:26724046

  15. Anvil cell gasket design for high pressure nuclear magnetic resonance experiments beyond 30 GPa

    NASA Astrophysics Data System (ADS)

    Meier, Thomas; Haase, Jürgen

    2015-12-01

    Nuclear magnetic resonance (NMR) experiments are reported at up to 30.5 GPa of pressure using radiofrequency (RF) micro-coils with anvil cell designs. These are the highest pressures ever reported with NMR, and are made possible through an improved gasket design based on nano-crystalline powders embedded in epoxy resin. Cubic boron-nitride (c-BN), corundum (α-Al2O3), or diamond based composites have been tested, also in NMR experiments. These composite gaskets lose about 1/2 of their initial height up to 30.5 GPa, allowing for larger sample quantities and preventing damages to the RF micro-coils compared to precipitation hardened CuBe gaskets. It is shown that NMR shift and resolution are less affected by the composite gaskets as compared to the more magnetic CuBe. The sensitivity can be as high as at normal pressure. The new, inexpensive, and simple to engineer gaskets are thus superior for NMR experiments at high pressures.

  16. Single Crystal Preparation for High-Pressure Experiments in the Diamond Anvil Cell

    SciTech Connect

    Aracne, C; Farber, D; Benterou, J; Occelli, F; Krisch, M; Antonangeli, D; Requardt, H; Fiquet, G

    2003-07-01

    Most research conducted in diamond anvil cells (DAC) is performed on polycrystalline samples. While data from polycrystalline samples are sufficient for determining the bulk properties, high-pressure experiments on single crystals allow for measurements on a range of tensor properties such as: thermal and electrical conductivity; magnetic susceptibility; elasticity; and plasticity. However, in order to achieve pressures above 1 Mbar in a DAC, single crystal samples must be <50 m in diameter and <15 m thick while maintaining a high degree of crystallinity. Thus, we have developed new procedures for producing extremely high-quality micro single crystal samples from commercially available material. Our sample preparation steps include cutting, classical metallographic polishing, and laser ablation. The key to our new process is the preservation of crystallinity during cutting and thinning. We have been successful in maintaining orientation, along with an extremely high degree of crystallinity in completed metal samples. To date, we have analyzed cobalt and molybdenum samples with both white-light interferometry and synchrotron x-ray diffraction, and are in the process of extending these methods to other metals and ceramics.

  17. Transformation-deformation bands in C60 after the treatment in a shear diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Kulnitskiy, B. A.; Blank, V. D.; Levitas, V. I.; Perezhogin, I. A.; Popov, M. Yu; Kirichenko, A. N.; Tyukalova, E. V.

    2016-04-01

    The C60 fullerene has been investigated by high-resolution transmission electron microscopy and electron energy loss spectroscopy in a shear diamond anvil cell after applying pressure and shear deformation treatment of fcc phase. Shear transformation-deformation bands are revealed consisting of shear-strain-induced nanocrystals of linearly polymerized fullerene and polytypes, the triclinic, monoclinic, and hcp C60, fragments of amorphous structures, and voids. Consequently, after pressure release, the plastic strain retains five high pressure phases, which is potentially important for their engineering applications. Localized shear deformation initially seems contradictory because high pressure phases of C60 are stronger than the initial low pressure phase. However, this was explained by transformation-induced plasticity during localized phase transformations. It occurs due to a combination of applied stresses and internal stresses from a volume reduction during phase transformations. Localized phase transformations and plastic shear deformation promote each other, which produce positive mechanochemical feedback and cascading transformation-deformation processes. Since the plastic shear in a band is much larger than is expected based on the torsion angle, five phase transformations occur in the same region with no transformation outside the band. The results demonstrate that transformation kinetics cannot be analyzed in terms of prescribed shear, and methods to measure local shear should be developed.

  18. Sound velocity of iron up to 152 GPa by picosecond acoustics in diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Decremps, F.; Antonangeli, D.; Gauthier, M.; Ayrinhac, S.; Morand, M.; Marchand, G. Le; Bergame, F.; Philippe, J.

    2014-03-01

    High-pressure method combining diamond anvil cell with picosecond ultrasonics technique is demonstrated to be a very suitable tool to measure the acoustic properties of iron up to 152 GPa. Such innovative approach allows to measure directly the longitudinal sound velocity under pressure of hundreds of GPa in laboratory, overcoming most of the drawbacks of traditional techniques. The very high accuracy, comparable to piezoacoustics technique, allows to observe the kink in elastic properties at the body-centered cubic-hexagonal close packed transition and to show with a good confidence that the Birch's law still stands up to 1.5 Mbar and ambient temperature. The linear extrapolation of the measured sound velocities versus densities of hcp iron is out of the preliminary reference Earth model, arguing for alloying effects or anharmonic high-temperature effects. A comparison between our measurements and shock wave experiments allowed us to quantify temperature corrections at constant pressure in ~-0.35 and ~-0.30 m s-1/K at 100 and 150 GPa, respectively. More in general, the here-presented technique allows detailed elastic and viscoelastic studies under extreme thermodynamic conditions on a wide variety of systems as liquids, crystalline, or polycrystalline solids, metallic or not, with very broad applications in Earth and planetary science.

  19. X-ray diffraction in the pulsed laser heated diamond anvil cell

    SciTech Connect

    Goncharov, Alexander F.; Prakapenka, Vitali B.; Struzhkin, Viktor V.; Kantor, Innokenty; Rivers, Mark L.; Dalton, D. Allen

    2010-11-03

    We have developed in situ x-ray synchrotron diffraction measurements of samples heated by a pulsed laser in the diamond anvil cell at pressure up to 60 GPa. We used an electronically modulated 2–10 kHz repetition rate, 1064–1075 nm fiber laser with 1–100 μs pulse width synchronized with a gated x-ray detector (Pilatus) and time-resolved radiometric temperature measurements. This enables the time domain measurements as a function of temperature in a microsecond time scale (averaged over many events, typically more than 10,000). X-ray diffraction data, temperature measurements, and finite element calculations with realistic geometric and thermochemical parameters show that in the present experimental configuration, samples 4 μm thick can be continuously temperature monitored (up to 3000 K in our experiments) with the same level of axial and radial temperature uniformities as with continuous heating. We find that this novel technique offers a new and convenient way of fine tuning the maximum sample temperature by changing the pulse width of the laser. This delicate control, which may also prevent chemical reactivity and diffusion, enables accurate measurement of melting curves, phase changes, and thermal equations of state.

  20. X-ray diffraction in the pulsed laser heated diamond anvil cell

    SciTech Connect

    Goncharov, Alexander F.; Prakapenka, Vitali B.; Struzhkin, Viktor V.; Kantor, Innokenty; Rivers, Mark L.; Dalton, D. Allen

    2010-11-19

    We have developed in situ x-ray synchrotron diffraction measurements of samples heated by a pulsed laser in the diamond anvil cell at pressure up to 60 GPa. We used an electronically modulated 2-10 kHz repetition rate, 1064-1075 nm fiber laser with 1-100 {micro}s pulse width synchronized with a gated x-ray detector (Pilatus) and time-resolved radiometric temperature measurements. This enables the time domain measurements as a function of temperature in a microsecond time scale (averaged over many events, typically more than 10,000). X-ray diffraction data, temperature measurements, and finite element calculations with realistic geometric and thermochemical parameters show that in the present experimental configuration, samples 4 {micro}m thick can be continuously temperature monitored (up to 3000 K in our experiments) with the same level of axial and radial temperature uniformities as with continuous heating. We find that this novel technique offers a new and convenient way of fine tuning the maximum sample temperature by changing the pulse width of the laser. This delicate control, which may also prevent chemical reactivity and diffusion, enables accurate measurement of melting curves, phase changes, and thermal equations of state.

  1. X-ray diffraction in the pulsed laser heated diamond anvil cell

    SciTech Connect

    Goncharov, Alexander F.; Struzhkin, Viktor V.; Dalton, D. Allen; Prakapenka, Vitali B.; Kantor, Innokenty; Rivers, Mark L.

    2010-11-15

    We have developed in situ x-ray synchrotron diffraction measurements of samples heated by a pulsed laser in the diamond anvil cell at pressure up to 60 GPa. We used an electronically modulated 2-10 kHz repetition rate, 1064-1075 nm fiber laser with 1-100 {mu}s pulse width synchronized with a gated x-ray detector (Pilatus) and time-resolved radiometric temperature measurements. This enables the time domain measurements as a function of temperature in a microsecond time scale (averaged over many events, typically more than 10 000). X-ray diffraction data, temperature measurements, and finite element calculations with realistic geometric and thermochemical parameters show that in the present experimental configuration, samples 4 {mu}m thick can be continuously temperature monitored (up to 3000 K in our experiments) with the same level of axial and radial temperature uniformities as with continuous heating. We find that this novel technique offers a new and convenient way of fine tuning the maximum sample temperature by changing the pulse width of the laser. This delicate control, which may also prevent chemical reactivity and diffusion, enables accurate measurement of melting curves, phase changes, and thermal equations of state.

  2. An in situ approach to study trace element partitioning in the laser heated diamond anvil cell.

    PubMed

    Petitgirard, S; Borchert, M; Andrault, D; Appel, K; Mezouar, M; Liermann, H-P

    2012-01-01

    Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample melting based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth. PMID:22299967

  3. Aerosol observations and growth rates downwind of the anvil of a deep tropical thunderstorm

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, H.-W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-07-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvil of a deep tropical thunderstorm. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol with diameter greater than 10 nm were 25 000 cm-3 (STP). By calculating back-trajectories from the observations, and projecting onto infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of about 3 hours was derived for the Aitken aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes >10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  4. Precise magnetoresistance and Hall resistivity measurements in the diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Boye, Shawn A.; Rosén, Daniel; Lazor, Peter; Katardjiev, Ilia

    2004-11-01

    An experimental system in combination with a technique for creating samples has been developed for conducting magnetotransport measurements of 3d ferromagnets as a function of temperature and pressure. Polycrystalline Ni0.985O0.015 thin film samples have been manufactured for experiments at zero pressure and in the diamond anvil cell (DAC) such that the contacts are of a predetermined size. This ensures that the placement of the leads in the pressure chamber of the DAC does not affect the quality of the measurement. Magnetoresistance and Hall resistivity measurements are preformed using the van der Pauw technique and the constant current method. The performance of the experimental apparatus is demonstrated by magnetotransport measurements of Ni0.985O0.015 thin films between 285 and 455 K in applied magnetic fields up to 10 T. The change in magnetic resistivity measured in the transverse configuration at zero pressure in the DAC, -0.0162(2) μΩ cm T-1 at 297 K, is observed to be negative and linear up to the maximum applied field. The extraordinary Hall coefficient measured at zero pressure and 297 K is found to be RE=-30.4(1)×10-10 m3 C-1.

  5. Online remote control systems for static and dynamic compression and decompression using diamond anvil cells

    NASA Astrophysics Data System (ADS)

    Sinogeikin, Stanislav V.; Smith, Jesse S.; Rod, Eric; Lin, Chuanlong; Kenney-Benson, Curtis; Shen, Guoyin

    2015-07-01

    The ability to remotely control pressure in diamond anvil cells (DACs) in accurate and consistent manner at room temperature, as well as at cryogenic and elevated temperatures, is crucial for effective and reliable operation of a high-pressure synchrotron facility such as High Pressure Collaborative Access Team (HPCAT). Over the last several years, a considerable effort has been made to develop instrumentation for remote and automated pressure control in DACs during synchrotron experiments. We have designed and implemented an array of modular pneumatic (double-diaphragm), mechanical (gearboxes), and piezoelectric devices and their combinations for controlling pressure and compression/decompression rate at various temperature conditions from 4 K in cryostats to several thousand Kelvin in laser-heated DACs. Because HPCAT is a user facility and diamond cells for user experiments are typically provided by users, our development effort has been focused on creating different loading mechanisms and frames for a variety of existing and commonly used diamond cells rather than designing specialized or dedicated diamond cells with various drives. In this paper, we review the available instrumentation for remote static and dynamic pressure control in DACs and show some examples of their applications to high pressure research.

  6. [Research on the experiment of hydrogen isotope fractionation using diamond anvil cell and Raman spectra].

    PubMed

    Wang, Shi-xia; Zheng, Hai-fei

    2011-03-01

    Hydrothermal diamond-anvil cell and Raman spectroscopy were used to measure the hydrogen isotope fractionation factor between gypsum and liquid water. Hydrogen isotopes of deuterium (D) and hydrogen (H) show the largest relative mass difference in all stable isotope systems. The exchange reaction between D and H would easily take place and the extent of exchange would be larger than others under same condition. So we selected the hydrogen isotopes for the investigation. The concept of fractionation factor is the quotient of ratios of heavy and light isotopes in different minerals, and can be expressed as alpha(A-B) = R(A)/R(B). There is a linear relationship between ratio of Raman peak intensities and ratio of corresponding amount of substances. So the fractionation factor between gypsum and heavy water can be expressed as [formula: see text] The experimental study for the isotope fractionation is based on the dissolution and recrystallization of minerals in aqueous solutions. The process can reach the total isotope fractionation equilibrium and get isotope fractionation factors with different temperatures. Compared with other methods, chemical synthesis one has following advantages: (1) short time for the experiment; (2) no problem about the equilibrium for isotope exchanges. It was proved that the new method would be more convenient and reliable for obtaining the isotopic fractionation factor compared with previous ways. PMID:21595220

  7. Dynamic Diamond Anvil Cell (dDAC): A novel device for studying the dynamic-pressure properties of materials

    SciTech Connect

    Evans, W J; Yoo, C; Lee, G W; Cynn, H; Lipp, M J; Visbeck, K

    2007-02-23

    We have developed a unique device, a dynamic diamond anvil cell (dDAC), which repetitively applies a time-dependent load/pressure profile to a sample. This capability allows studies of the kinetics of phase transitions and metastable phases at compression (strain) rates of up to 500 GPa/sec ({approx}0.16 s{sup -1} for a metal). Our approach adapts electromechanical piezoelectric actuators to a conventional diamond anvil cell design, which enables precise specification and control of a time-dependent applied load/pressure. Existing DAC instrumentation and experimental techniques are easily adapted to the dDAC to measure the properties of a sample under the varying load/pressure conditions. This capability addresses the sparsely studied regime of dynamic phenomena between static research (diamond anvil cells and large volume presses) and dynamic shock-driven experiments (gas guns, explosive and laser shock). We present an overview of a variety of experimental measurements that can be made with this device.

  8. Calibration of an isotopically enriched carbon-13 layer pressure sensor to 156 GPa in a diamond anvil cell

    SciTech Connect

    Qiu,W.; Baker, P.; Velisavljevic, N.; Vohra, Y.; Weir, S.

    2006-01-01

    An isotopically enriched {sup 13}C homoepitaxial diamond layer of 6{+-}1 {mu}m thickness was grown on top of a brilliant cut diamond anvil by a microwave plasma chemical vapor deposition process for application as a pressure sensor. This isotopically enriched diamond tip was then used in conjunction with a natural isotopic abundance diamond anvil to generate high pressure on the sample. We provide a calibration for the {sup 13}C Raman mode of this extremely thin epitaxial layer to 156 GPa using ruby fluorescence and the equation of state of copper as secondary pressure standards. The nonlinear calibration of the {sup 13}C Raman mode pressure sensor is compared with similar calibrations of {sup 12}C Raman edge and a good agreement is obtained. The Raman signal from the {sup 13}C epitaxial layer remained a distinct singlet to 156 GPa, and pressure calibration is independent of sample mechanical strength or the diamond anvil geometry. The use of even thinner layer would allow calibration further into ultrahigh pressure regime where the use of other optical sensors has proven to be difficult.

  9. Magnetic measurements at pressures above 10 GPa in a miniature ceramic anvil cell for a superconducting quantum interference device magnetometer

    PubMed Central

    Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma D.; Fisk, Zachary

    2012-01-01

    A miniature ceramic anvil high pressure cell (mCAC) was earlier designed by us for magnetic measurements at pressures up to 7.6 GPa in a commercial superconducting quantum interference magnetometer [N. Tateiwa , Rev. Sci. Instrum. 82, 053906 (2011)]10.1063/1.3590745. Here, we describe methods to generate pressures above 10 GPa in the mCAC. The efficiency of the pressure generation is sharply improved when the Cu-Be gasket is sufficiently preindented. The maximum pressure for the 0.6 mm culet anvils is 12.6 GPa when the Cu-Be gasket is preindented from the initial thickness of 300–60 μm. The 0.5 mm culet anvils were also tested with a rhenium gasket. The maximum pressure attainable in the mCAC is about 13 GPa. The present cell was used to study YbCu2Si2 which shows a pressure induced transition from the non-magnetic to magnetic phases at 8 GPa. We confirm a ferromagnetic transition from the dc magnetization measurement at high pressure. The mCAC can detect the ferromagnetic ordered state whose spontaneous magnetic moment is smaller than 1 μB per unit cell. The high sensitivity for magnetic measurements in the mCAC may result from the simplicity of cell structure. The present study shows the availability of the mCAC for precise magnetic measurements at pressures above 10 GPa. PMID:22667632

  10. Effect of shear stress on the high-pressure behaviour of nitromethane: Raman spectroscopy in a shear diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Hebert, Philippe; Isambert, Aude; Petitet, Jean-Pierre; Zerr, Andreas

    2009-06-01

    A detailed description of the reaction mechanisms occurring in shock-induced decomposition of condensed energetic materials is very important for a comprehensive understanding of detonation. Besides pressure and temperature effects, shear stress has also been proposed to play an important role in the initiation and decomposition mechanisms. In order to study this effect, a Shear Diamond Anvil Cell (SDAC) has been developed. It is actually a classical DAC with the upper diamond anvil rotating about the compression axis relative to the opposite anvil. In this paper, we present a Raman spectroscopy study of the effect of shear stress on the high-pressure behaviour of nitromethane. Two major effects of shear stress are observed in our experiments. The first one is a lowering of the pressures at which the different structural modifications that nitromethane undergoes are observed. The second effect is observed at 28 GPa where sudden decomposition of the sample occurs just after shear application. Observation of the sample after decomposition shows the presence of a black residue which is composed of carbon as indicated by the Raman spectrum. [1] Manaa, M. R., Fried, L. E., and Reed, E. J., Journal of Computer-Aided Materials Design, 10, pp 75-97, 2003.

  11. Present State-of-the-Art and Future Developments in COMPRES Synchrotron-Based Multi-Anvil Research

    NASA Astrophysics Data System (ADS)

    Whitaker, M. L.; Chen, H.; Vaughan, M. T.; Weidner, D. J.; Baldwin, K. J.; Huebsch, W. B.

    2013-12-01

    Understanding the properties and behaviors of materials and multi-phase aggregates under conditions of high pressure and temperature are vital to unraveling the mysteries that lie beneath the surface of the planet. Advances in in situ experimental techniques utilizing synchrotron radiation at these extreme conditions have helped to provide answers to many fundamental questions that were previously unattainable. In particular, the Multi-Anvil apparatus has proven to be an invaluable tool for studying the morphological characteristics and physical properties of materials under extreme conditions as a function of pressure, temperature, stress, strain, and time. Moreover, the science is still continuing to evolve, and we have begun to step outside the realm of the static into the study of dynamic processes and their real-time responses to changes in the aforementioned variables, and even to the frequency and rate of these changes. This presentation will discuss the evolution and present state of the art in synchrotron-based multi-anvil techniques at the COMPRES-funded X17MAC Facility at the National Synchrotron Light Source, and will also present future projections of developing techniques that will redefine the future of multi-anvil research not only at this facility, but also as we look forward to the impending move to our new home at beamline 6BM-B at the Advanced Photon Source.

  12. Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

    SciTech Connect

    Hunt, Simon A. McCormack, Richard J.; Bailey, Edward; Dobson, David P.; Weidner, Donald J.; Whitaker, Matthew L.; Li, Li; Vaughan, Michael T.

    2014-08-15

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1–2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C.

  13. Deformation T-Cup: a new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa.

    PubMed

    Hunt, Simon A; Weidner, Donald J; McCormack, Richard J; Whitaker, Matthew L; Bailey, Edward; Li, Li; Vaughan, Michael T; Dobson, David P

    2014-08-01

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1-2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C . PMID:25173308

  14. Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

    NASA Astrophysics Data System (ADS)

    Hunt, Simon A.; Weidner, Donald J.; McCormack, Richard J.; Whitaker, Matthew L.; Bailey, Edward; Li, Li; Vaughan, Michael T.; Dobson, David P.

    2014-08-01

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1-2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C .

  15. Constraints on the Aleutian Subduction Zone from the Shumagin Gap to Kodiak Asperity from New MCS and OBS Data of the ALEUT Project

    NASA Astrophysics Data System (ADS)

    Shillington, D. J.; Nedimović, M. R.; Webb, S. C.; Bécel, A.; Delescluse, M.; Li, J.; Kuehn, H.; Biescas, B.; Wessbecher, A.; Farkas, A.; Eddy, C.; Hostetler, K.; Perls, H.; Zietman, J.; Keranen, K. M.; Louden, K. E.

    2011-12-01

    In July-August 2011, the Alaska Langseth Experiment to Understand the megaThrust (ALEUT) program acquired deep penetration multichannel seismic (MCS) reflection and ocean bottom seismometer (OBS) data along a part of the Aleutian subduction zone that exhibits the full spectrum of coupling, from locked to freely slipping. The goal of this program is to characterize variations in the geometry and properties of the megathrust, over-riding and downgoing plates and other structures and relate them to downdip and along-strike changes in slip behavior and seismogenesis. Our study encompassed 1) the freely slipping Shumagin Gap; 2) the locked Semidi segment, which last ruptured in 1938, and 3) the locked western Kodiak asperity, the western extent of the 1964 M9.2 rupture. We acquired 3700 km of MCS data with the R/V Langseth along a series of strike and dip profiles that span the entire locked zone on the megathrust (as indicated by GPS data and estimated rupture zones of past earthquakes), its updip and downdip transitions to stable sliding, bending of the downgoing plate, and preexisting structures in the oceanic crust. Data were acquired with a 6600 cu. in. air gun array and two 8-km-long streamers. The source and one of the streamers were towed at a depth of 12 m to maximize low frequencies (and deep imaging) while the second streamer was towed at 9 m for better imaging of the sediments and upper crust. Refraction data were acquired using the same source and short period OBS spaced at ~15 km along two ~400-km profiles coincident with MCS data across the Shumagin Gap and Semidi segment. Eight seismometers were also deployed onshore in the summer of 2011 that recorded the entire offshore experiment plus local and regional seismicity. Here we present initial results from MCS and OBS data regarding the megathrust and the hydration of the downgoing plate. Initial images reveal deep reflections from the megathrust from both the locked region and the estimated downdip

  16. Contrasting a non-developing African mesoscale convective system with the precursor to Hurricane Helene (2006)

    NASA Astrophysics Data System (ADS)

    Rivera, G.; Fuentes, J. D.; Evans, J. L.; Hamilton, H. L.

    2015-12-01

    Mesoscale convective systems (MCSs) in West Africa traverse strong thermodynamic gradients during their westward propagation from land to ocean. Some of the systems continue to develop after crossing the coastline and may ultimately develop into tropical cyclones, while others do not. Understanding the lifecycle behavior of these convective systems and the factors that contribute to their continuous development as they transition from a continental environment to a marine environment poses a challenge. We examine the difference between two MCSs, one that continued to develop when it crossed the West African coast and one that did not, using European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA Interim) and Tropical Rainfall Measurement Mission (TRMM) 3B42 data. The non-developing MCS that intensified briefly while over land, weakened as soon as it crossed the coast. Preliminary results show that the developing MCS interacted with two cyclonic vortices, one associated with an African Easterly Wave that was propagating towards the coast and the other vortex generated by the topography near the coast.

  17. Time- and Space-Domain Measurements of the Thermal Conductivity in Diamond Anvil Cells

    NASA Astrophysics Data System (ADS)

    Goncharov, A. F.

    2011-12-01

    I will give an overview of recent developments of experimental techniques to measure the thermal conductivity in diamond anvil cell (DAC) under conditions of high pressure and high temperature (P-T) which are relevant for the planetary interiors. To measure the lattice contributions to the thermal conductivity, we developed a transient heating technique (THT) in the diamond anvil cell (DAC) [1]. This technique utilizes a periodic front surface temperature variation (measured by the spectroradiometry) of a metallic absorber surrounded by the material of interest and exposed to a pulsed laser radiation (10 nanoseconds pulses). We extract the thermal diffusivity of minerals by fitting the experimental results to the model finite element (FE) calculations. We have recently modified this technique for microseconds laser pulses as this allows avoiding nonequilibrium heat transfer processes. We have measured the thermal conductivity of Ar up to 50 GPa and 2500 K; the results are in agreement with the theoretical calculations [2] in the limit of high temperatures. In collaboration with a group from the University of Illinois we have utilized a time-domain thermoreflectance (TDTR)- ultrafast (femtosecond) laser pump-probe technique for measurement of the lattice thermal conductivity at high P-T conditions. We have measured the thermal conductivity of MgO up to 60 GPa and 300 K and up to 45 GPa at 600 K. The detailed results of this study will be presented in a separate paper at this Meeting. Finally, we have combined static and pulsed laser techniques to determine the thermal conductivity of Fe and its temperature dependence at high pressures up to 70 GPa and 2000 K [3]. A thin plate of Fe was positioned in an Ar medium, laser heated from one side and the temperature is being measured from both sides of the sample radiometrically. The thermal conductivity has been determined by fitting the results of FE calculations to the experimental results. These examples demonstrate

  18. Probing iron spin state by optical absorption in laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Lobanov, S.; Goncharov, A. F.; Holtgrewe, N.; Lin, J. F.

    2015-12-01

    Pressure-induced spin-pairing transitions in iron-bearing minerals have been in the focus of geophysical studies1. Modern consensus is that iron spin state in the lower mantle is a complex function of crystal structure, composition, pressure, and temperature. Discontinuities in physical properties of lower mantle minerals have been revealed over the spin transition pressure range, but at room temperature. In this work, we have used a supercontinuum laser source and an intensified CCD camera to probe optical properties of siderite, FeCO3, and post-perovskite, Mg0.9Fe0.1SiO3, across the spin transition in laser-heated diamond anvil cell. Synchronously gating the CCD with the supercontinuum pulses (Fig. 1A) allowed diminishing thermal background to ~8.3*10-4. Utilizing the experimental setup we infer the spin state of ferrous iron in siderite at high pressure and temperature conditions (Fig. 1B). Similar behavior is observed for low spin ferric iron in post-perovskite at 130 GPa indicating that all iron in post-perovskite is high spin at lower mantle conditions. Also, our experimental setup holds promise for measuring radiative thermal conductivity of mantle minerals at relevant mantle conditions. Figure 1. (A) Timing of the optical absorption measurements at high temperature. (B) High temperature siderite absorption spectra at 45 GPa. Before heating and quenched after 1300 K spectra are shown in light and dark blue, respectively. Green and red curves are absorption spectra at 1200 K and 1300 K, respectively. Spectra shown in black represent room temperature absorption data on HS (43 GPa) and LS (45.5 GPa) siderite after Lobanov et al., 2015, shown for comparison.

  19. Single Crystal Preparation for High Pressure Experiments in the Diamond Anvil Cell.

    NASA Astrophysics Data System (ADS)

    Aracne, C. M.; Farber, D. L.; Occelli, F.; Antonangeli, D.; Badro, J.

    2003-12-01

    Measuring the effects of pressure on geomaterials in deep Earth's P-T conditions using the diamond anvil cell (DAC) is essential for understanding the phase transition mechanisms, the mechanical properties (which derives directly from the determination of the elastic constants), and the transport properties of deep-Earth materials. To date, most DAC research has been performed with polycrystalline samples. While these are sufficient for determining orientationally averaged properties of solids (i.e. bulk modulus, P-waves and S-wave aggregate velocities, etc\\ldots), single crystals offer the ability to measure a range of direction dependent properties (i.e. thermal and electrical conductivity, elasticity and plasticity, etc\\ldots). Subsequent comparison of measurements on single-\\ and poly-crystalline materials can, for instance, make it possible to address the effects of pressure on the elastic anisotropy and preferred orientations in deep Earth's conditions. In order to achieve pressures above 1 Mbar, one must produce single crystal samples ˜25 μ m in diameter and less than 10 μ m thick. We have developed procedures to produce extremely high-quality metallic single crystals of this size from commercially available material with millimeter dimensions. Critical to the final product is the preservation of crystallinity during thinning and cutting. Our surface preparation methods include the use of selected abrasives, colloidal silica polishing and chemical etching. Samples are cut to final shape using a laser-ablation facility that can handle both conductive and insulating materials. To date, we have been successful in maintaining an extremely high degree of crystallinity and orientation in the final samples. Presently, we have analyzed cobalt and molybdenum samples with both white-light interferometry and synchrotron x-ray diffraction and are in the process of extending these methods to other metals and minerals, such as zinc, sapphire, and olivine.

  20. Observations on the crystallization of spodumene from aqueous solutions in a hydrothermal diamond-anvil cell

    USGS Publications Warehouse

    Li, Jianking; Chou, I-Ming; Yuan, Shunda; Burruss, Robert A.

    2013-01-01

    Crystallization experiments were conducted in a new type of hydrothermal diamond-anvil cell (HDAC; type V) using LiAlSi2O6 (S) gel and H2O (W) as starting materials. A total of 21 experiments were performed at temperatures up to 950°C and pressures up to 788 MPa. In the samples with relatively low W/S ratios, many small crystals formed in the melt phase during cooling. In those with high W/S ratios, only a few crystals with smooth surfaces crystallized from the aqueous fluid in the presence of melt droplets, which were gradually consumed during crystal growth, indicating rapid transfer of material from the melt to the crystals through the aqueous fluid. The nucleation of crystals started at 710 (±70)°C and 520 (±80) MPa, and crystal growth ended at 570 (±40)°C and 320 (±90) MPa, with the cooling P-T path within the stability field of spodumene + quartz in the S-W system. The observed linear crystal growth rates in the aqueous phase, calculated by dividing the maximum length of a single crystal by the duration of the entire growth step, were 4.7 × 10−6 and 5.7 × 10−6 cm s−1 for the cooling rates of 0.5 and 1°C min−1, respectively. However, a rapid crystal growth rate of 3.6 × 10−5 cm s−1 in the aqueous fluid was observed when the components were supplied by nearby melt droplets. Our results show that when crystals nucleate in the aqueous fluid instead of the melt phase, there are fewer nuclei formed, and they grow much faster due to the low viscosity of the aqueous fluid, which accelerates diffusion of components for the growth of crystals. Therefore, the large crystals in granitic pegmatite can crystallize directly from aqueous fluids rather than hydrosilicate melt.

  1. Time-Domain X-ray Diffraction in the Pulsed Laser Heated Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Prakapenka, V.; Goncharov, A. F.; Struzhkin, V.; Kantor, I.; Rivers, M. L.; Dalton, D. A.

    2011-12-01

    We have developed in situ x-ray synchrotron diffraction measurements of samples heated by a pulsed laser in the diamond anvil cell (DAC) at pressure up to 100 GPa and 3500 K. We used an electronically modulated 2-10 kHz repetition rate, 1064-1075 nm fiber laser with 1-100 microseconds pulse width synchronized with a gated x-ray detector (Pilatus) and time resolved radiometric temperature measurements. For the special APS hybrid mode, the measurements were also synchronized with a 500 ns long bunch carrying 88% of the ring current. This setup enables time domain measurements as a function of temperature in a micrometers time scale (averaged over many events, typically more than 10,000). X-ray diffraction data, temperature measurements, and finite element calculations with realistic geometric and thermochemical parameters show that in the present experimental configuration samples 4 micrometers thick can be continuously temperature monitored (up to 3000 K in our experiments) with the same level of axial and radial temperature uniformity as with continuous heating. We find that this novel technique offers a new and convenient way of fine tuning the maximum sample temperature by changing the pulse width of the laser. We will show examples of studies of the melting, thermal equation of state, and chemical reactivity. We acknowledge support from NSF EAR-0842057, DOE/ NNSA (CDAC), and EFree, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DESC0001057. X-ray diffraction measurements were performed at GSECARS (APS) supported by DOE Contract No.W-31-109- Eng-38.

  2. Precise measurements of radial temperature gradients in the laser-heated diamond anvil cell.

    PubMed

    Kavner, A; Nugent, C

    2008-02-01

    A new spectroradiometry system specialized for measuring two-dimensional temperature gradients for samples at high pressure in the laser heated diamond anvil cell has been designed and constructed at UCLA. Emitted light intensity from sample hotspots is imaged by a videocamera for real time monitoring, an imaging spectroradiometer for temperature measurement, and a high-dynamic-range camera that examines a magnified image of the two-dimensional intensity distribution of the heated spot, yielding precise measurements of temperature gradients. With this new system, most systematic errors in temperature measurement due to chromatic aberration are bypassed. We use this system to compare several different geometries of temperature measurement found in the literature, including scanning a pinhole aperture, and narrow-slit and wide-slit entrance apertures placed before the imaging spectrometer. We find that the most accurate way of measuring a temperature is to use the spectrometer to measure an average hotspot temperature and to use information from the imaging charge coupled device to calculate the temperature distribution to the hotspot. We investigate the effects of possible wavelength- and temperature-dependent emissivity, and evaluate their errors. We apply this technique to measure the anisotropy in temperature distribution of highly oriented graphite at room temperature and also at high pressures. A comparison between model and experiment demonstrates that this system is capable of measuring thermal diffusivity in anisotropic single crystals and is also capable of measuring relative thermal diffusivity at high pressures and temperatures among different materials. This shows the possibility of using this system to provide information about thermal diffusivity of materials at high pressure and temperature. PMID:18315322

  3. A CloudSat cloud object partitioning technique and assessment and integration of deep convective anvil sensitivities to sea surface temperature

    NASA Astrophysics Data System (ADS)

    Igel, Matthew R.; Drager, Aryeh J.; Heever, Susan C.

    2014-09-01

    A cloud object partitioning algorithm is developed to provide a widely useful database of deep convective clouds. It takes contiguous CloudSat cloudy regions and identifies various length scales of clouds from a tropical, oceanic subset of data. The methodology identifies a level above which anvil characteristics become important by analyzing the cloud object shape. Below this level in what is termed the pedestal region, convective cores are identified based on reflectivity maxima. Identifying these regions allows for the assessment of length scales of the anvil and pedestal of deep convective clouds. Cloud objects are also appended with certain environmental quantities from European Centre for Medium-Range Weather Forecasts. Simple geospatial and temporal assessments show that the cloud object technique agrees with standard observations of local frequency of deep convective cloudiness. Deep convective clouds over tropical oceans play important roles in Earth's climate system. The newly developed data set is used to evaluate the response of tropical, deep convective clouds to sea surface temperature (SST). Several previously proposed responses are examined: the Fixed Anvil Temperature Hypothesis, the Iris Hypothesis, and the Thermostat Hypothesis. When the data are analyzed per cloud object, increasing SST is found to be associated with increased anvil thickness, decreased anvil width, and cooler cloud top temperatures. Implications for the corresponding hypotheses are discussed. A new response suggesting that the base temperature of deep convective anvils remains approximately constant with increasing SSTs is introduced. These cloud dependencies on SST are integrated to form a more comprehensive theory for deep convective anvil responses to SST.

  4. African and non-African admixture components in African Americans and an African Caribbean population.

    PubMed

    Murray, Tanda; Beaty, Terri H; Mathias, Rasika A; Rafaels, Nicholas; Grant, Audrey Virginia; Faruque, Mezbah U; Watson, Harold R; Ruczinski, Ingo; Dunston, Georgia M; Barnes, Kathleen C

    2010-09-01

    Admixture is a potential source of confounding in genetic association studies, so it becomes important to detect and estimate admixture in a sample of unrelated individuals. Populations of African descent in the US and the Caribbean share similar historical backgrounds but the distributions of African admixture may differ. We selected 416 ancestry informative markers (AIMs) to estimate and compare admixture proportions using STRUCTURE in 906 unrelated African Americans (AAs) and 294 Barbadians (ACs) from a study of asthma. This analysis showed AAs on average were 72.5% African, 19.6% European and 8% Asian, while ACs were 77.4% African, 15.9% European, and 6.7% Asian which were significantly different. A principal components analysis based on these AIMs yielded one primary eigenvector that explained 54.04% of the variation and captured a gradient from West African to European admixture. This principal component was highly correlated with African vs. European ancestry as estimated by STRUCTURE (r(2)=0.992, r(2)=0.912, respectively). To investigate other African contributions to African American and Barbadian admixture, we performed PCA on approximately 14,000 (14k) genome-wide SNPs in AAs, ACs, Yorubans, Luhya and Maasai African groups, and estimated genetic distances (F(ST)). We found AAs and ACs were closest genetically (F(ST)=0.008), and both were closer to the Yorubans than the other East African populations. In our sample of individuals of African descent, approximately 400 well-defined AIMs were just as good for detecting substructure as approximately 14,000 random SNPs drawn from a genome-wide panel of markers. PMID:20717976

  5. The African superswell

    NASA Technical Reports Server (NTRS)

    Nyblade, Andrew A.; Robinson, Scott W.

    1994-01-01

    Maps of residual bathymetry in the ocean basins around the African continent reveal a broad bathymetric swell in the southeastern Atlantic Ocean with an amplitude of about 500 m. We propose that this region of anomalously shallow bathymetry, together with the contiguous eastern and southern African plateaus, form a superswell which we refer to as the African superswell. The origin of the African superswell is uncertain. However, rifting and volcanism in eastern Africa, as well as heat flow measurements in southern Africa and the southeastern Atlantic Ocean, suggest that the superswell may be attributed, at least in part, to heating of the lithosphere.

  6. Acoustic travel time gauges for in-situ determination of pressure and temperature in multi-anvil apparatus

    NASA Astrophysics Data System (ADS)

    Wang, Xuebing; Chen, Ting; Qi, Xintong; Zou, Yongtao; Kung, Jennifer; Yu, Tony; Wang, Yanbin; Liebermann, Robert C.; Li, Baosheng

    2015-08-01

    In this study, we developed a new method for in-situ pressure determination in multi-anvil, high-pressure apparatus using an acoustic travel time approach within the framework of acoustoelasticity. The ultrasonic travel times of polycrystalline Al2O3 were calibrated against NaCl pressure scale up to 15 GPa and 900 °C in a Kawai-type double-stage multi-anvil apparatus in conjunction with synchrotron X-radiation, thereby providing a convenient and reliable gauge for pressure determination at ambient and high temperatures. The pressures derived from this new travel time method are in excellent agreement with those from the fixed-point methods. Application of this new pressure gauge in an offline experiment revealed a remarkable agreement of the densities of coesite with those from the previous single crystal compression studies under hydrostatic conditions, thus providing strong validation for the current travel time pressure scale. The travel time approach not only can be used for continuous in-situ pressure determination at room temperature, high temperatures, during compression and decompression, but also bears a unique capability that none of the previous scales can deliver, i.e., simultaneous pressure and temperature determination with a high accuracy (±0.16 GPa in pressure and ±17 °C in temperature). Therefore, the new in-situ Al2O3 pressure gauge is expected to enable new and expanded opportunities for offline laboratory studies of solid and liquid materials under high pressure and high temperature in multi-anvil apparatus.

  7. Acoustic travel time gauges for in-situ determination of pressure and temperature in multi-anvil apparatus

    SciTech Connect

    Wang, Xuebing; Chen, Ting; Qi, Xintong; Zou, Yongtao; Liebermann, Robert C.; Li, Baosheng; Kung, Jennifer; Yu, Tony; Wang, Yanbin

    2015-08-14

    In this study, we developed a new method for in-situ pressure determination in multi-anvil, high-pressure apparatus using an acoustic travel time approach within the framework of acoustoelasticity. The ultrasonic travel times of polycrystalline Al{sub 2}O{sub 3} were calibrated against NaCl pressure scale up to 15 GPa and 900 °C in a Kawai-type double-stage multi-anvil apparatus in conjunction with synchrotron X-radiation, thereby providing a convenient and reliable gauge for pressure determination at ambient and high temperatures. The pressures derived from this new travel time method are in excellent agreement with those from the fixed-point methods. Application of this new pressure gauge in an offline experiment revealed a remarkable agreement of the densities of coesite with those from the previous single crystal compression studies under hydrostatic conditions, thus providing strong validation for the current travel time pressure scale. The travel time approach not only can be used for continuous in-situ pressure determination at room temperature, high temperatures, during compression and decompression, but also bears a unique capability that none of the previous scales can deliver, i.e., simultaneous pressure and temperature determination with a high accuracy (±0.16 GPa in pressure and ±17 °C in temperature). Therefore, the new in-situ Al{sub 2}O{sub 3} pressure gauge is expected to enable new and expanded opportunities for offline laboratory studies of solid and liquid materials under high pressure and high temperature in multi-anvil apparatus.

  8. Strain-induced phase transformation under compression in a diamond anvil cell: Simulations of a sample and gasket

    NASA Astrophysics Data System (ADS)

    Feng, Biao; Levitas, Valery I.; Ma, Yanzhang

    2014-04-01

    Combined high pressure phase transformations (PTs) and plastic flow in a sample within a gasket compressed in diamond anvil cell (DAC) are studied for the first time using finite element method. The key point is that phase transformations are modelled as strain-induced, which involves a completely different kinetic description than for traditional pressure-induced PTs. The model takes into account, contact sliding with Coulomb and plastic friction at the boundaries between the sample, gasket, and anvil. A comprehensive computational study of the effects of the kinetic parameter, ratio of the yield strengths of high and low-pressure phases and the gasket, sample radius, and initial thickness on the PTs and plastic flow is performed. A new sliding mechanism at the contact line between the sample, gasket, and anvil called extrusion-based pseudoslip is revealed, which plays an important part in producing high pressure. Strain-controlled kinetics explains why experimentally determined phase transformation pressure and kinetics (concentration of high pressure phase vs. pressure) differ for different geometries and properties of the gasket and the sample: they provide different plastic strain, which was not measured. Utilization of the gasket changes radial plastic flow toward the center of a sample, which leads to high quasi-homogeneous pressure for some geometries. For transformation to a stronger high pressure phase, plastic strain and concentration of a high-pressure phase are also quasi-homogeneous. This allowed us to suggest a method of determining strain-controlled kinetics from experimentation, which is not possible for weaker and equal-strength high-pressure phases and cases without a gasket. Some experimental phenomena are reproduced and interpreted. Developed methods and obtained results represent essential progress toward the understanding of PTs under compression in the DAC. This will allow one optimal design of experiments and conditions for synthesis of new

  9. STEP-BY-STEP ESOPHAGOJEJUNAL ANASTOMOSIS AFTER INTRA-CORPOREAL TOTAL GASTRECTOMY FOR LAPAROSCOPIC GASTRIC CANCER TREATMENT: TECHNIQUE OF "REVERSE ANVIL"

    PubMed Central

    LACERDA, Croider Franco; BERTULUCCI, Paulo Anderson; de OLIVEIRA, Antônio Talvane Torres

    2014-01-01

    Background The laparoscopic gastrectomy is a relatively new procedure due mainly to the difficulties related to lymphadenectomy and reconstruction. Until the moment, technique or device to perform the esophagojejunal anastomosis by laparoscopy is still a challenge. So, a safe, cheap and quickly performing technique is desirable to be developed. Aim To present technique proposed by the authors with its technical details on reconstruction with "reverse anvil". Method After total gastrectomy completed intra-corporeally, the reconstruction starts with the preparation of the intra-abdominal esophagus cross-section next to the esophagogastric transition of 50%. A graduated device is prepared using Levine gastric tubes (nº. 14 and 10), 3 cm length, connected to the anvil of the circular stapler (nº. 25) with a wire thread (2-0 or 3-0) of 10 cm, which is connected to end of this device. The whole device is introduced in reverse esophagus. The esophagus is amputated and the wire is pulled after previous transfixation in the distal esophagus and the anvil positioned. The jejunal loop is sectioned 20-30 cm from duodenojejunal angle, and the anvil put in the jejunal loop and connect previously in the esophagus. Linear stapler (blue 60 mm) is used to close the opening of the jejunal loop. Conclusion The "reverse anvil" technique used by the authors facilitated the transit reestablishment after total gastrectomy, contributing to obviate reconstruction problems after total gastrectomy. PMID:24676304

  10. An Electrical Micro-Heater Technique for High-Pressure and High-Temperature Diamond Anvil Cell Experiments

    SciTech Connect

    Weir, S T; Jackson, D D; Falabella, S; Samudrala, G; Vohra, Y K

    2008-10-10

    Small electrical heating elements have been lithographically fabricated onto the culets of 'designer' diamond anvils for the purpose of performing high-pressure and high-temperature experiments on metals. The thin-film geometry of the heating elements makes them very resistant to plastic deformation during high pressure loading, and their small cross-sectional area enables them to be electrically heated to very high temperatures with relatively modest currents ({approx}1 Amp). The technique also offers excellent control and temporal stability of the sample temperature. Test experiments on gold samples have been performed for pressures up to 21 GPa and temperatures of nearly 2000K.

  11. 3D analytical investigation of melting at lower mantle conditions in the laser-heated diamond anvil cel

    NASA Astrophysics Data System (ADS)

    Nabiei, F.; Cantoni, M.; Badro, J.; Dorfman, S. M.; Gaal, R.; Piet, H.; Gillet, P.

    2015-12-01

    The diamond anvil cell is a unique tool to study materials under static pressures up to several hundreds of GPa. It is possible to generate temperatures as high as several thousand degrees in the diamond anvil cell by laser heating. This allows us to achieve deep mantle conditions in the laser-heated diamond anvil cell (LHDAC). The small heated volume is surrounded by thermally conductive diamond anvils results in high temperature gradients which affect phase transformation and chemical distribution in the LH-DAC. Analytical characterization of samples in three dimensions is essential to fully understand phase assemblages and equilibrium in LHDAC. In this study we used San Carlos olivine as a starting material as a simple proxy to deep mantle composition. Three samples were melted at ~3000 K and at ~45 GPa for three different durations ranging from 1 to 6 minutes; two other samples were melted at 30 GPa and 70 GPa. All samples were then sliced by focused ion beam (FIB). From each slice, an electron image and energy dispersive X-ray (EDX) map were acquired by scanning electron microscope (SEM) in the dual beam FIB instrument. These slices were collected on one half of the heated area in each sample, from which we obtained 3D elemental and phase distribution. The other half of the heated area was used to extract a 100 nm thick section for subsequent analysis by analytical transmission electron microscopy (TEM) to obtain diffraction patterns and high resolution EDX maps. 3D reconstruction of SEM EDX results shows at least four differentiated regions in the heated area for all samples. The exact Fe and Mg compositions mentioned below are an example of the sample melted at 45 GPa for 6 minutes. The bulk of the heated are is surrounded by ferropericlase (Mg0.92, Fe0.08)O shell (Fp). Inside this shell we find a thick region of (Mg,Fe)SiO3 perovskite-structured bridgmanite (Brg) coexisting with Fp. In the center lies a Fe-rich core which is surrounded by magnesiow

  12. Effect of Shear Strain on the High-Pressure Behavior of Nitromethane: Raman Spectroscopy in a Shear Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Hébert, P.; Isambert, A.; Petitet, J. P.; Zerr, A.

    2009-12-01

    The effect of shear strain on the high-pressure behavior of nitromethane has been studied by Raman spectroscopy in a shear diamond anvil cell (SDAC). Two major effects of shear strain have been observed. The first one is a lowering of the pressures at which the different spectral transformations occur. The second effect is observed at 28 GPa. At this pressure, a sudden decomposition of the sample occurs due to the shear deformation. Observation of the sample after decomposition shows the presence of a black residue, which is mainly composed of carbon soot.

  13. 2.09 - Theory and Practice - Diamond - Anvil Cells and Probes for High P - T Mineral Physics Studies

    SciTech Connect

    Mao, H -K; Mao, W L

    2008-09-18

    With the rapid emergence of diamond-anvil cell (DAC) research as a major dimension in physical sciences, the literature is growing at an explosive rate. A comprehensive discussion of any one of the sections could easily fill a whole book. Therefore, our strategy is to introduce the essential concept for each subject, lay out the key background, then jump to the latest activities on technical developments, mineral physical applications, current problems, and future prospects. Ample references are provided for readers who seek a deeper understanding of these topics.

  14. Peculiar Features of Microstructure Formation and Microhardness Variations During Torsional Straining of Tantalum Specimens in Bridgman Anvils

    NASA Astrophysics Data System (ADS)

    Ditenberg, I. A.; Tymentsev, A. N.; Korznikov, A. V.

    2015-04-01

    Using the method of transmission electron microscopy, peculiar features of evolution of microstructure and variations in microhardness of Та are investigated under torsional loading in the Bridgman anvil as a function of plastic deformation at room temperature. A quantitative examination of grain and defect's structure of the material under study and the values of local internal stresses is performed in different loading stages. The mechanisms of formation of submicrocrystalline and nanostructured states are analyzed and so is the microstructure variation as a function of the defect-structure characteristics, strain level, and spacing from the axis of torsion.

  15. Deciphering the mechanics of an imaged fault system in the over-riding plate at the Shumagin Seismic Gap, Alaska subduction zone using MCS waveform tomography

    NASA Astrophysics Data System (ADS)

    Michaelson, C. A.; Delescluse, M.; Becel, A.; Nedimovic, M. R.; Shillington, D. J.; Louden, K. E.; Webb, S. C.

    2013-12-01

    The 2011 ALEUT program acquired 3500 km of multichannel seismic (MCS) data along a part of the western Alaska subduction zone, from the freely slipping Shumagin Seismic Gap to the locked regions in the Semidi segment and the western Kodiak asperity. The MCS profiles were acquired on the R/V Langseth using two 8-km-long streamers and span the entire locked zone on the megathrust, including the updip and downdip transitions to stable sliding. The primary goal was to characterize variations in the geometry and properties of the megathrust and the downgoing plate and relate them to downdip and along-strike changes in slip behavior and seismogenesis. The images capture the targeted megathrust reflectivity and its spatial variation. Notably, the two westernmost profiles show reflections arising from a major fault in the overriding plate within the Shumagin Seismic Gap located 75 km from the trench, which can be followed from the seafloor to the megathrust. The imaged normal fault bounds the seaward end of the Sanak forearc Cenozoic basin, formed after the Early Eocene reorganization of the Alaska subduction zone. The new reflection images also show that the seaward pair of the previously interpreted growth faults, thought to indicate deposition contemporaneous with basin subsidence, is a part of the imaged fault system. The unexpected imaging of this major fault system in the over-riding plate raises important questions: Has this fault been active during the most recent nearby megathrust earthquakes, such as the 1946 and 1948 earthquakes? Was the Sanak basin formed as a result of slip on the imaged normal fault system or is it a result of growth faulting that predates the formation of this fault? The timing and style of deformation on this fault has significant implications for both coupling on the megathrust seaward and landward of where the normal fault roots and tsunamigenesis. To complement constraints on the geometry and reflection characteristics of this structure

  16. Strong composition-dependent variation of MCs + calibration factors in TiO x and GeO x ( x ≤ 2) films

    NASA Astrophysics Data System (ADS)

    Gnaser, Hubert; Le, Yongkang; Su, Weifeng

    2006-07-01

    The emission of MCs + secondary ions (M designates the analyte species) from TiO x (0.2 ≤ x ≤ 2) and GeO x (0.001 ≤ x ≤ 0.8) films under Cs + bombardment was examined. The relative calibration factors of OCs +/TiCs + and OCs +/GeCs + were determined and were found to depend pronouncedly on the O/Ti and O/Ge atomic concentration ratios. Specifically, with increasing oxygen content OCs + ions form much more efficiently (as compared to TiCs + or GeCs + ions), an enhancement amounting to more than a factor of 10 for the highest oxygen concentrations. Concurrently, the formation of TiOCs + or GeOCs + ions increases drastically. For both oxide systems, an empirical relation for the oxygen-concentration dependence of the relative calibration factors could be established.

  17. Tropical deep convective life cycle: Cb-anvil cloud microphysics from high altitude aircraft observations

    NASA Astrophysics Data System (ADS)

    Frey, W.; Borrmann, S.; Fierli, F.; Weigel, R.; Mitev, V.; Matthey, R.; Ravegnani, F.; Sitnikov, N. M.; Ulanovsky, A.; Cairo, F.

    2014-05-01

    The case study presented here focusses on the life cycle of clouds in a tropical deep convective system. During the SCOUT-O3 campaign from Darwin, Northern Australia, the Hector storm system has been probed by the Geophysica high altitude aircraft. Clouds were observed by in situ particle probes, a backscatter sonde, and a miniature lidar. Additionally, aerosol number concentrations have been measured. On 30 November 2005 a double flight took place and Hector was probed throughout its life cycle in its developing, mature, and dissipating stage. The two flights were four hours apart and focussed on the anvil region of Hector in altitudes between 10.5 km and 18.8 km (i.e. above 350 K potential temperature). Trajectory calculations and ozone measurements have been used to identify that the same cloud air masses have been probed in both flights. The size distributions derived from the measurements not only show a change with increasing altitude but also with the evolution of Hector. Clearly different aerosol to cloud particle ratios as well as varying ice crystal morphology have been found for the different development stages of Hector, indicating a change in freezing mechanisms. The development phase exhibits the smallest ice particles (up to 300 μm) with a rather uniform morphology. This is indicative for rapid glaciation during Hector's development. Sizes of ice crystals are largest in the mature stage (larger 1.6 mm) and even exceed those of some continental tropical deep convective clouds, also in their number concentrations. The backscatter properties and particle images show a change from frozen droplets in the developing phase to rimed and aggregated particles. The clouds in the dissipating stage have a large vertical extend (roughly 6 km) though optically thin and persist for at least 6 h. This poses a high potential for affecting the tropical tropopause layer background conditions regarding humidity, e.g. through facilitating subvisible cirrus formation, and

  18. Temperature Distribution in Multi-Anvil Assemblies Derived From Spinel Layer Growth

    NASA Astrophysics Data System (ADS)

    van Westrenen, W.; Van Orman, J. A.; Van Orman, J. A.; Fei, Y.; Watson, E. B.

    2001-12-01

    Experiments performed at pressures (P) and temperatures (T) relevant to planetary interiors often require uniform heating of the experimental charge. Quantitative knowledge of the thermal structure of high-pressure assemblies is needed to determine maximum sample volumes and optimize assembly design. We present measurements of the T distribution in a range of multi-anvil assemblies, at P between 6 - 14 GPa, and at T up to 2250 K, based on the growth rate of a MgAl2O4 spinel layer at the interface between MgO and Al2O3 assembly filler pieces. Recently, Watson et al. (CMP, in press) presented an empirical equation linking the thickness of a spinel layer growing at the interface between MgO and Al2O3 to P, T, and time. Their equation is based on experiments performed in a piston cylinder apparatus, at P up to 4 GPa and T up to 2250 K. We extend the P range of this equation to 14 GPa, using standard 18/11, 10/5 and 8/3 pressure cells. In the 18/11 and 10/5 assemblies with straight graphite and Re furnaces respectively, the upper half contained an alumina rod (enclosing thermocouple wires) surrounded by an MgO cylinder, while the lower half consisted of alumina tubing sandwiched between MgO cylinders. The 8/3 assembly (with a Re foil heater) consisted of an outer alumina cylinder filled with MgO. Spinel layer thicknesses were obtained from high-resolution X-ray maps of sectioned and polished run products using an electron probe. In the 18/11 assembly, at 6 GPa and 2123 K, axial T remains constant within 2 mm of the assembly center. From the edges of this 'hot spot' T decreases parabolically with distance. The radial gradient is small (on the order of 15 K over 0.5 mm distance from the center of the assembly). At 14 GPa in the 8/3 assembly the hot spot is close to 1 mm long. T gradients outside the hot spot are large: 2 mm from the assembly center T has decreased by around 175 K. At 14 GPa, spinel growth is significantly slower than expected from the Watson et al

  19. Comparisons of Anvil Cirrus Spatial Characteristics between Airborne Observations in DC3 Campaign and WRF Simulations

    NASA Astrophysics Data System (ADS)

    D'Alessandro, J.; Diao, M.; Chen, M.

    2015-12-01

    John D'Alessandro1, Minghui Diao1, Ming Chen2, George Bryan2, Hugh Morrison21. Department of Meteorology and Climate Science, San Jose State University2. Mesoscale & Microscale Meteorology Division, National Center for Atmospheric Research, Boulder, CO, 80301 Ice crystal formation requires the prerequisite condition of ice supersaturation, i.e., relative humidity with respect to ice (RHi) greater than 100%. The formation and evolution of ice supersaturated regions (ISSRs) has large impact on the subsequent formation of ice clouds. To examine the characteristics of simulated ice supersaturated regions at various model spatial resolutions, case studies between airborne in-situ measurements in the NSF Deep Convective, Clouds and Chemistry (DC3) campaign (May - June 2012) and WRF simulations are conducted in this work. Recent studies using ~200 m in-situ observations showed that ice supersaturated regions are mostly around 1 km in horizontal scale (Diao et al. 2014). Yet it is still unclear if such observed characteristics can be represented by WRF simulations at various spatial resolutions. In this work, we compare the WRF simulated anvil cirrus spatial characteristics with those observed in the DC3 campaign over the southern great plains in US. The WRF model is run at 1 km and 3 km horizontal grid spacing with a recent update of Thompson microphysics scheme. Our comparisons focus on the spatial characteristics of ISSRs and cirrus clouds, including the distributions of their horizontal scales, the maximum relative humidity with respect to ice (RHi) and the relationship between RHi and temperature. Our previous work on the NCAR CM1 cloud-resolving model shows that the higher resolution runs (i.e., 250m and 1km) generally have better agreement with observations than the coarser resolution (4km) runs. We will examine if similar trend exists for WRF simulations in deep convection cases. In addition, we will compare the simulation results between WRF and CM1, particularly

  20. 16 Extraordinary African Americans.

    ERIC Educational Resources Information Center

    Lobb, Nancy

    This collection for children tells the stories of 16 African Americans who helped make America what it is today. African Americans can take pride in the heritage of these contributors to society. Biographies are given for the following: (1) Sojourner Truth, preacher and abolitionist; (2) Frederick Douglass, abolitionist; (3) Harriet Tubman, leader…

  1. African Studies Computer Resources.

    ERIC Educational Resources Information Center

    Kuntz, Patricia S.

    African studies computer resources that are readily available in the United States with linkages to Africa are described, highlighting those most directly corresponding to African content. Africanists can use the following four fundamental computer systems: (1) Internet/Bitnet; (2) Fidonet; (3) Usenet; and (4) dial-up bulletin board services. The…

  2. African Literature as Celebration.

    ERIC Educational Resources Information Center

    Achebe, Chinua

    1989-01-01

    Describes the Igbo tradition of "Mbari," a communal creative enterprise that celebrates the world and the life lived in it through art. Contrasts the cooperative, social dimension of pre-colonial African culture with the exclusion and denial of European colonialism, and sees new African literature again celebrating human presence and dignity. (AF)

  3. Educating African American Males

    ERIC Educational Resources Information Center

    Bell, Edward E.

    2010-01-01

    Background: Schools across America spend money, invest in programs, and sponsor workshops, offer teacher incentives, raise accountability standards, and even evoke the name of Obama in efforts to raise the academic achievement of African American males. Incarceration and college retention rates point to a dismal plight for many African American…

  4. Africans Away from Home.

    ERIC Educational Resources Information Center

    Clarke, John Henrik

    Africans who were brought across the Atlantic as slaves never fully adjusted to slavery or accepted its inevitability. Resistance began on board the slave ships, where many jumped overboard or committed suicide. African slaves in South America led the first revolts against tyranny in the New World. The first slave revolt in the Caribbean occurred…

  5. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  6. Diabetes in African Americans

    PubMed Central

    Marshall, M

    2005-01-01

    African Americans have a high risk for type 2 diabetes. Genetic traits, the prevalence of obesity, and insulin resistance all contribute to the risk of diabetes in the African American community. African Americans have a high rate of diabetic complications, because of poor glycaemic control and racial disparities in health care in the USA. African Americans with diabetes may have an atypical presentation that simulates type 1 diabetes, but then their subsequent clinical course is typical of type 2 diabetes. Culturally sensitive strategies, structured disease management protocols, and the assistance of nurses, diabetic educators, and other health care professionals are effective in improving the outcome of diabetes in the African American community. PMID:16344294

  7. African bees to control African elephants

    NASA Astrophysics Data System (ADS)

    Vollrath, Fritz; Douglas-Hamilton, Iain

    2002-11-01

    Numbers of elephants have declined in Africa and Asia over the past 30 years while numbers of humans have increased, both substantially. Friction between these two keystone species is reaching levels which are worryingly high from an ecological as well as a political viewpoint. Ways and means must be found to keep the two apart, at least in areas sensitive to each species' survival. The aggressive African bee might be one such method. Here we demonstrate that African bees deter elephants from damaging the vegetation and trees which house their hives. We argue that bees can be employed profitably to protect not only selected trees, but also selected areas, from elephant damage.

  8. In Situ Raman Spectroscopic Study of Barite as a Pressure Gauge Using a Hydrothermal Diamond Anvil Cell.

    PubMed

    Liu, Chuanjiang; Wang, Duojun; Zheng, Haifei

    2016-02-01

    In situ Raman measurements of barite were performed at temperatures in the range of 298-673 K and pressures in the range of 105-1217 MPa using a hydrothermal diamond anvil cell combined with laser Raman spectroscopy. The Raman frequency and the full width at half maximum (FWHM) of the most intense ν1 Raman peak for barite as a function of pressure and temperature were obtained. In the experimental P-T ranges, the ν1Raman band systematically shifted toward low wavenumbers with increasing pressure and temperature. The positive pressure dependence of ν1Raman frequency indicates stress-induced shortening of the S-O bond, whereas the negative temperature dependence shows temperature-induced expansion of the S-O bond. In contrast, the observed ν1Raman band became broadened, which should be attributed to the reduced ordering of molecular structure. Based on the obtained data, the established relationships among the Raman shift or the FWHM, pressure and temperature can be used to obtain good estimates of the internal pressure in natural barite-bearing fluid inclusions or hydrothermal diamond anvil cell. This is a sensitive and reliable approach to the accurate determination of geological pressure. PMID:26903568

  9. Application of Cloud Vertical Structure to Investigate the Microphysical and Optical Properties of Cirriform, Anvil, and Deep Convective Clouds

    NASA Astrophysics Data System (ADS)

    Bates, J. J.; Young, A. H.; Curry, J. A.

    2012-12-01

    This study uses cloud vertical structure (CVS) to evaluate the optical and microphysical properties of high clouds including cirriform, anvil, and deep convection (DC) over the region between 35°S-35°N for a 1-yr period from January-December 2007. The analyses are based on integrated multisensory pixel-level observations of CVS from CloudSat/CALIPSO and Level 2 cloud data from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite. Cloud products evaluated include mean cloud optical thickness, cloud effective radius, cloud-top temperature, cloud-top pressure, cloud brightness temperature, and cloud effective emissivity. Unlike other studies, high clouds investigated in this study are not determined by the International Satellite Cloud Climatology Project (ISCCP) cloud classification scheme. Instead it relies on the CloudSat 2B-CLDCLASS product which uses radar reflectivity data and also considers the spatial and horizontal cloud structure to classify cirriform, anvil, and DC clouds. Results of the study are used to evaluate the capabilities of MODIS to estimate cloud properties and identify the impacts of using CVS to classify various types of high level clouds rather than the ISCCP cloud classification scheme. Applications of the study's results include potential improvements to precipitation retrievals and the representation of cloud systems in general circulation models.

  10. Use of a miniature diamond-anvil cell in high-pressure single-crystal neutron Laue diffraction.

    PubMed

    Binns, Jack; Kamenev, Konstantin V; McIntyre, Garry J; Moggach, Stephen A; Parsons, Simon

    2016-05-01

    The first high-pressure neutron diffraction study in a miniature diamond-anvil cell of a single crystal of size typical for X-ray diffraction is reported. This is made possible by modern Laue diffraction using a large solid-angle image-plate detector. An unexpected finding is that even reflections whose diffracted beams pass through the cell body are reliably observed, albeit with some attenuation. The cell body does limit the range of usable incident angles, but the crystallographic completeness for a high-symmetry unit cell is only slightly less than for a data collection without the cell. Data collections for two sizes of hexamine single crystals, with and without the pressure cell, and at 300 and 150 K, show that sample size and temperature are the most important factors that influence data quality. Despite the smaller crystal size and dominant parasitic scattering from the diamond-anvil cell, the data collected allow a full anisotropic refinement of hexamine with bond lengths and angles that agree with literature data within experimental error. This technique is shown to be suitable for low-symmetry crystals, and in these cases the transmission of diffracted beams through the cell body results in much higher completeness values than are possible with X-rays. The way is now open for joint X-ray and neutron studies on the same sample under identical conditions. PMID:27158503

  11. Use of a miniature diamond-anvil cell in high-pressure single-crystal neutron Laue diffraction

    PubMed Central

    Binns, Jack; Kamenev, Konstantin V.; McIntyre, Garry J.; Moggach, Stephen A.; Parsons, Simon

    2016-01-01

    The first high-pressure neutron diffraction study in a miniature diamond-anvil cell of a single crystal of size typical for X-ray diffraction is reported. This is made possible by modern Laue diffraction using a large solid-angle image-plate detector. An unexpected finding is that even reflections whose diffracted beams pass through the cell body are reliably observed, albeit with some attenuation. The cell body does limit the range of usable incident angles, but the crystallographic completeness for a high-symmetry unit cell is only slightly less than for a data collection without the cell. Data collections for two sizes of hexamine single crystals, with and without the pressure cell, and at 300 and 150 K, show that sample size and temperature are the most important factors that influence data quality. Despite the smaller crystal size and dominant parasitic scattering from the diamond-anvil cell, the data collected allow a full anisotropic refinement of hexamine with bond lengths and angles that agree with literature data within experimental error. This technique is shown to be suitable for low-symmetry crystals, and in these cases the transmission of diffracted beams through the cell body results in much higher completeness values than are possible with X-rays. The way is now open for joint X-ray and neutron studies on the same sample under identical conditions. PMID:27158503

  12. High quality x-ray absorption spectroscopy measurements with long energy range at high pressure using diamond anvil cell

    PubMed Central

    Hong, Xinguo; Newville, Matthew; Prakapenka, Vitali B.; Rivers, Mark L.; Sutton, Stephen R.

    2009-01-01

    We describe an approach for acquiring high quality x-ray absorption fine structure (XAFS) spectroscopy spectra with wide energy range at high pressure using diamond anvil cell (DAC). Overcoming the serious interference of diamond Bragg peaks is essential for combining XAFS and DAC techniques in high pressure research, yet an effective method to obtain accurate XAFS spectrum free from DAC induced glitches has been lacking. It was found that these glitches, whose energy positions are very sensitive to the relative orientation between DAC and incident x-ray beam, can be effectively eliminated using an iterative algorithm based on repeated measurements over a small angular range of DAC orientation, e.g., within ±3° relative to the x-ray beam direction. Demonstration XAFS spectra are reported for rutile-type GeO2 recorded by traditional ambient pressure and high pressure DAC methods, showing similar quality at 440 eV above the absorption edge. Accurate XAFS spectra of GeO2 glass were obtained at high pressure up to 53 GPa, providing important insight into the structural polymorphism of GeO2 glass at high pressure. This method is expected be applicable for in situ XAFS measurements using a diamond anvil cell up to ultrahigh pressures. PMID:19655966

  13. Use of Taylor Rod-on-Anvil Impact Experiments to Investigate High Strain Rate Behaviour in Polyolefins

    NASA Astrophysics Data System (ADS)

    Bucknall, David; Luce, Amanda; Kannan, Abhiram; Breidenich, Jennifer; Thadhani, Naresh

    2015-06-01

    The high strain rate deformation and mechano-lumination of various polyethylenes and polypropylene is studied using Taylor rod-on-anvil impact testing. Polypropylene and low density (LDPE), high density (HDPE), and ultra high molecular weight (UHMWPE) polyethylene samples were impacted against a hardened steel anvil at velocities ranging from 50-500 m/s. High-speed imaging, time-resolved spectroscopy, and thermal imaging are employed to track the macroscopic shape change and observe mechano-lumination and heating during impact. Additionally, electron spin resonance (ESR) and gel permeation chromatography (GPC) measurements were performed on recovered impacted samples to explain the observed deformation behavior in the various polyolefins. Time-resolved spectroscopy, coupled with ESR and GPC measurements indicate that chain scission occurs during the first few microseconds of the impact event. The observed macroscopic deformation that occurs after the observed mechano-illumination event is therefore influenced by the loss of mechanical strength associated with a drop in the molecular weight of the polymer.

  14. High quality x-ray absorption spectroscopy measurements with long energy range at high pressure using diamond anvil cell

    SciTech Connect

    Hong, X.; Newville, M.; Prakapenka, V.B.; Rivers, M.L.; Sutton, S.R.

    2009-07-31

    We describe an approach for acquiring high quality x-ray absorption fine structure (XAFS) spectroscopy spectra with wide energy range at high pressure using diamond anvil cell (DAC). Overcoming the serious interference of diamond Bragg peaks is essential for combining XAFS and DAC techniques in high pressure research, yet an effective method to obtain accurate XAFS spectrum free from DAC induced glitches has been lacking. It was found that these glitches, whose energy positions are very sensitive to the relative orientation between DAC and incident x-ray beam, can be effectively eliminated using an iterative algorithm based on repeated measurements over a small angular range of DAC orientation, e.g., within {+-}3{sup o} relative to the x-ray beam direction. Demonstration XAFS spectra are reported for rutile-type GeO{sub 2} recorded by traditional ambient pressure and high pressure DAC methods, showing similar quality at 440 eV above the absorption edge. Accurate XAFS spectra of GeO{sub 2} glass were obtained at high pressure up to 53 GPa, providing important insight into the structural polymorphism of GeO{sub 2} glass at high pressure. This method is expected be applicable for in situ XAFS measurements using a diamond anvil cell up to ultrahigh pressures.

  15. Instrumented Taylor anvil-on-rod impact tests for validating applicability of standard strength models to transient deformation states

    NASA Astrophysics Data System (ADS)

    Eakins, D. E.; Thadhani, N. N.

    2006-10-01

    Instrumented Taylor anvil-on-rod impact tests have been conducted on oxygen-free electronic copper to validate the accuracy of current strength models for predicting transient states during dynamic deformation events. The experiments coupled the use of high-speed digital photography to record the transient deformation states and laser interferometry to monitor the sample back (free surface) velocity as a measure of the elastic/plastic wave propagation through the sample length. Numerical continuum dynamics simulations of the impact and plastic wave propagation employing the Johnson-Cook [Proceedings of the Seventh International Symposium on Ballistics, 1983, The Netherlands (Am. Def. Prep. Assoc. (ADPA)), pp. 541-547], Zerilli-Armstrong [J. Appl. Phys. C1, 1816 (1987)], and Steinberg-Guinan [J. Appl. Phys. 51, 1498 (1980)] constitutive equations were used to generate transient deformation profiles and the free surface velocity traces. While these simulations showed good correlation with the measured free surface velocity traces and the final deformed sample shape, varying degrees of deviations were observed between the photographed and calculated specimen profiles at intermediate deformation states. The results illustrate the usefulness of the instrumented Taylor anvil-on-rod impact technique for validating constitutive equations that can describe the path-dependent deformation response and can therefore predict the transient and final deformation states.

  16. The Hydrothermal Diamond Anvil Cell (HDAC) for raman spectroscopic studies of geologic fluids at high pressures and temperatures

    USGS Publications Warehouse

    Schmidt, Christian; Chou, I-Ming

    2012-01-01

    In this chapter, we describe the hydrothermal diamond-anvil cell (HDAC), which is specifically designed for experiments on systems with aqueous fluids to temperatures up to ⬚~1000ºC and pressures up to a few GPa to tens of GPa. This cell permits optical observation of the sample and the in situ determination of properties by ‘photon-in photon-out’ techniques such as Raman spectroscopy. Several methods for pressure measurement are discussed in detail including the Raman spectroscopic pressure sensors a-quartz, berlinite, zircon, cubic boron nitride (c-BN), and 13C-diamond, the fluorescence sensors ruby (α-Al2O3:Cr3+), Sm:YAG (Y3Al5O12:Sm3+) and SrB4O7:Sm2+, and measurements of phase-transition temperatures. Furthermore, we give an overview of published Raman spectroscopic studies of geological fluids to high pressures and temperatures, in which diamond anvil cells were applied.

  17. Effect of laser annealing of pressure gradients in a diamond-anvil cell using common solid pressure media

    NASA Astrophysics Data System (ADS)

    Uts, Ilya; Glazyrin, Konstantin; Lee, Kanani K. M.

    2013-10-01

    Pressure media are one of the most effective deterrents of pressure gradients in diamond-anvil cell (DAC) experiments. The media, however, become less effective with increasing pressure, particularly for solid pressure media. One of the most popular ways of alleviating the increase in pressure gradients in DAC samples is through laser annealing of the sample. We explore the effectiveness of this technique for six common solid pressure media that include: alkali metal halides LiF, NaCl, KCl, CsCl, KBr, as well as amorphous SiO2. Pressure gradients are determined through the analysis of the first-order diamond Raman band across the sample before and after annealing the sample with a near-infrared laser to temperatures between ˜2000 and 3000 K. As expected, we find that in the absence of sample chamber geometrical changes and diamond anvil damage, laser annealing reduces pressure gradients, albeit to varying amounts. We find that under ideal conditions, NaCl provides the best deterrent to pressure gradients before and after laser annealing, at least up to pressures of 60 GPa and temperatures between ˜2000 and 3000 K. Amorphous SiO2, on the other hand, transforms in to harder crystalline stishovite upon laser annealing at high pressures resulting in increased pressure gradients upon further compression without laser annealing.

  18. Chapter 7: The hydrothermal diamond anvil cell (HDAC) for Raman spectroscopic studies of geological fluids at high pressures and temperatures

    USGS Publications Warehouse

    Schmidt, Christian; Chou, I-Ming

    2012-01-01

    In this chapter, we describe the hydrothermal diamond-anvil cell (HDAC), which is specifically designed for experiments on systems with aqueous fluids to temperatures up to ~1000ºC and pressures up to a few GPa to tens of GPa. This cell permits optical observation of the sample and the in situ determination of properties by ‘photon-in photon-out’ techniques such as Raman spectroscopy. Several methods for pressure measurement are discussed in detail including the Raman spectroscopic pressure sensors a-quartz, berlinite, zircon, cubic boron nitride (c-BN), and 13C-diamond, the fluorescence sensors ruby (α-Al2O3:Cr3+), Sm:YAG (Y3Al5O12:Sm3+) and SrB4O7:Sm2+, and measurements of phase-transition temperatures. Furthermore, we give an overview of published Raman spectroscopic studies of geological fluids to high pressures and temperatures, in which diamond anvil cells were applied.

  19. Diamond dissolution and the production of methane and other carbon-bearing species in hydrothermal diamond-anvil cells

    USGS Publications Warehouse

    Chou, I.-Ming; Anderson, Alan J.

    2009-01-01

    Raman analysis of the vapor phase formed after heating pure water to near critical (355-374 ??C) temperatures in a hydrothermal diamond-anvil cell (HDAC) reveals the synthesis of abiogenic methane. This unexpected result demonstrates the chemical reactivity of diamond at relatively low temperatures. The rate of methane production from the reaction between water and diamond increases with increasing temperature and is enhanced by the presence of a metal gasket (Re, Ir, or Inconel) which is compressed between the diamond anvils to seal the aqueous sample. The minimum detection limit for methane using Raman spectroscopy was determined to be ca. 0.047 MPa, indicating that more than 1.4 nanograms (or 8.6 ?? 10-11 mol) of methane were produced in the HDAC at 355 ??C and 30 MPa over a period of ten minutes. At temperatures of 650 ??C and greater, hydrogen and carbon dioxide were detected in addition to methane. The production of abiogenic methane, observed in all HDAC experiments where a gasket was used, necessitates a reexamination of the assumed chemical systems and intensive parameters reported in previous hydrothermal investigations employing diamonds. The results also demonstrate the need to minimize or eliminate the production of methane and other carbonic species in experiments by containing the sample within a HDAC without using a metal gasket.

  20. Impact of environmental conditions on the mesoscale characteristics of squall-line systems: Toward the development of anvil cirrus parameterization for GCMs

    SciTech Connect

    Chin, Hung-Neng S.; Bradley, M.M.

    1996-05-01

    Our earlier studies indicated that a strong coupling exists in the mesoscale convective systems (MCSs) between deep convection and its related anvil cloud through the interaction among dynamical, thermodynamical and radiative processes. They also showed that the tilting structure of MCSs makes an important contribution to the water budget of anvil clouds, particularly the tropical anvil due to the jetlike wind profile. However, most earlier GCMs did not include a direct and physically consistent representation of this coupling. To this end, Randall et al. suggested a more realistic anvil parameterization by adding prognostic cloud water (or ice) variables to account for the formation of anvil clouds from cumulus detrainment. In addition to this effort, our recent studies further suggest the need to parameterize the tilting structure of MCSs in GCMs. The objective of this work is to parameterize the large-scale effects of this tilting structure. Our primary interest focuses on MCSs in an environment with substantial wind shear, such as squall-line systems, since they have longer lifetimes and wider coverage to affect the earth-atmosphere radiation budget and climate. Using varied convective available potential energy (CAPE), wind shear intensity, shear depth, and the pattern of shear profile over a wide range of bulk Richardson number (Ri), a sensitivity study is performed in a cloud resolving model to link its resulting mesoscale ascent/descent with GCM-resolvable variables. The ultimate goal of this research is to develop an anvil cirrus parameterization (ACP), that will couple with cumulus parameterizations in GCMs to improve the cloud-radiation feedback on large-scale climate.

  1. DDIA-30: a Versatile Megabar Mutli-anvil Device for in-situ High Pressure Studies with White and Monochromatic Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Jing, Z.; Hilairet, N.; Yu, T.; Nishiyama, N.; Tange, Y.; Sakamaki, T.; Rivers, M. L.; Sutton, S. R.

    2010-12-01

    We report installation and test results of the DDIA-30 apparatus, a new high pressure device jointly supported by GSECARS and COMPRES. This module is now operational in the 1000 ton press in at the insertion device beamline (13-ID-D) of the Advanced Photon Source. With the operational principle similar to that of the deformation DIA (D-DIA) [1], the DDIA-30 is much larger in size, with anvil truncation edge lengths (TEL) in excess of 30 mm and hydraulic load capacity of 1000 tons. The upper and lower guide blocks have built-in differential hydraulic rams, so that the upper and lower anvils can be driven independently, generating a controlled differential stress field. When operated in single-stage mode, the device allows large samples (up to ~10 mm) to be deformed under high pressure and temperature, in a way identical to the small D-DIA that has been in operation since 2004 at 13-BM-D. The large TEL and load capacity makes DDIA-30 more attractive in double-stage configurations. Without driving the differential rams, DDIA-30 is used to compress eight second-stage cubic anvils. This 6-8 (6 first-stage and 8 second-stage anvils) configuration has been demonstrated to reach 90+ GPa with sintered diamond as second-stage anvils [2, 3]. We have tested this configuration with both LaCrO3 and TiB2 as heater materials to 35 GPa and 1500 C and successfully conducted melting experiments on selected metals and alloys with energy-dispersive diffraction and imaging. Another type of second-stage configuration is to use six DIA anvil extensions with small TELs. This 6-6 configuration [4] allows deformation experiments to be conducted without having to change the large first-stage anvils when different sized cell assemblies are desired. Recent laboratory studies using a similar device in Japan have shown that the large guide blocks have unique advantages in maintaining anvil alignment, greatly expanding capability of the deformation DIA to 25 GPa and 2000 K [5]. Monochromatic

  2. Black versus Black: The Relationship among African, African American, and African Caribbean Persons.

    ERIC Educational Resources Information Center

    Jackson, Jennifer V.; Cothran, Mary E.

    2003-01-01

    Surveyed people of African descent regarding relationships among African, African-American, and African-Caribbean persons, focusing on contact and friendship, travel to countries of the diaspora, cross-cultural communication, thoughts and stereotypes, and education. Most respondents had contacts with the other groups, but groups had preconceived…

  3. Astronomy for African development

    NASA Astrophysics Data System (ADS)

    Govender, Kevindran

    2011-06-01

    In recent years there have been a number of efforts across Africa to develop the field of astronomy as well as to reap benefit from astronomy for African people. This presentation will discuss the case of the SALT (Southern African Large Telescope) Collateral Benefits Programme (SCBP) which was set up to ensure societal benefit from astronomy. With African society as the target, the SCBP has embarked on various projects from school level education to public understanding of science to socio-economic development, the latter mainly being felt in the rural communities surrounding the South African Astronomical Observatory (home to SALT). A development plan for ``Astronomy in Africa'' will also be discussed. This plan has been drawn up with input from all over Africa and themed ``Astronomy for Education''. The Africa case stands as a good example for the IYA cornerstone project ``Developing Astronomy Globally'' which focuses on developing regions.

  4. African American Suicide

    MedlinePlus

    ... accounted for 83.8% of Caucasian elderly suicides. • Firearms were the predominant method of suicide among African ... per 100,000 annually. Source: Centers for Disease Control and Prevention. National Vital Statistics System. Mortality Data. ...

  5. Deformation experiment on fayalite using deformation-Cubic Anvil, D-CAP 700, with synchrotron X rays

    NASA Astrophysics Data System (ADS)

    Ohnuma, R. S.; Ohtani, E.; Suzuki, A.; Kubo, T.; Doi, N.; Shimojuku, A.; Kato, T.; Kikegawa, T.

    2009-12-01

    Studies of the rheological properties of rocks and minerals are important for understanding the dynamics and evolution of the Earth’s mantle. A new deformation apparatus had been proposed by Durham et al. (2002) and the new apparatus is capable of deforming samples under confining pressure up to 15GPa. Basically, the new apparatus consists of the cubic-anvil apparatus known as the DIA and two differential rams, which is called the D-DIA. The system has been introduced into synchrotron X-ray beamlines, and a procedure for measuring stress and strain using synchrotron X-rays had been developed. So far, experiments using the deformation DIA with synchrotron X-rays have been conducted at only two beamlines, the GeoSoilEnviro CARS 13-BM-D beamline of the Advanced Photon Source and the X17B2 beamline of the National Synchrotron Light Source. So, we installed a deformation cubic anvil, D-CAP 700 at the 14C2 beamline of the Photon Factory, which is essentially similar to the conventional D-DIA system. The differential rams are driven by micro-discharge pumps, and the deformation cubic anvil component is driven by MAX-III 700ton press installed at the 14C2 beamline. Two differential rams are controlled by an oil pressure controller, and both of the pressure control and the displacement control are available. The displacements of two differential rams are measured by the stroke sensor attached to rams. An incident X-ray beam was monochromatized at energy of 50 keV by a monochromater. Strain is observed from transmitted X-ray imaging of sample using the YAG:Ce single crystal phosphor and the CCD camera. Stress is measured by analyzing the two dimensional diffraction patterns of samples. The two dimensional diffraction patterns are collected by an imaging plate. Using this new deformation apparatus, D-CAP 700 and the measurement system at the 14C2 beamline of the Photon Factory, we have conducted the deformation experiments of fayalite. Samples were deformed at a confining

  6. A simple external resistance heating diamond anvil cell and its application for synchrotron radiation x-ray diffraction

    SciTech Connect

    Fan Dawei; Zhou Wenge; Liu Yonggang; Xie Hongsen; Wei Shuyi; Ma Maining

    2010-05-15

    A simple external heating assemblage allowing diamond anvil cell experiments at pressures up to 34 GPa and temperatures up to 653 K was constructed. This cell can be connected to the synchrotron radiation conveniently. The design and construction of this cell are fully described, as well as its applications for x-ray diffraction. Heating is carried out by using an external-heating system, which is made of NiCr resistance wire, and the temperature was measured by a NiCr-NiSi or PtRh-Pt thermocouple. We showed the performance of the new system by introducing the phase transition study of cinnabar ({alpha}-HgS) and thermal equation of state study of almandine at high pressure and temperature with this cell.

  7. Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in-situ tunability

    SciTech Connect

    Palmer, Alexander; Silevitch, Daniel; Feng, Yejun; Wang, Yishu; Jaramillo, R.; Banerjee, Arnab; Ren, Yang; Rosenbaum, Thomas F.

    2015-09-04

    We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with that of the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we then characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide range of pressure, while at the same time making possible precise steps across abrupt phase transitions such as that from insulator to metal.

  8. A virtual experiment control and data acquisition system for in situ laser heated diamond anvil cell Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Subramanian, N.; Struzhkin, Viktor V.; Goncharov, Alexander F.; Hemley, Russell J.

    2010-09-01

    Doubled-sided laser heated diamond anvil cell methods allow simultaneous in situ confocal Raman measurements of materials up to megabar pressures and high temperatures. This paper describes a virtual control and data acquisition system developed to automate setups for simultaneous Raman/laser heating experiments. The system enables reduction of experiment time by ˜90% in comparison to manual operations, allowing measurements of high quality Raman spectra of even highly reactive or diffusive samples, such as hydrogen at extreme conditions using continuous wave laser heating. These types of measurements are very difficult and often impossible to obtain in a manual operation mode. Complete data archiving and accurate control of various experimental parameters (e.g., on-the-fly temperature determination and self-adjusting data collection time to avoid signal saturation) can be done, and open up possibilities of other types of experiments involving extreme conditions.

  9. A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

    NASA Astrophysics Data System (ADS)

    Feng, Yejun; Silevitch, D. M.; Rosenbaum, T. F.

    2014-03-01

    We present the design of an efficient bellows-controlled diamond anvil cell that is optimized for use inside the bores of high-field superconducting magnets in helium-3 cryostats, dilution refrigerators, and commercial physical property measurement systems. Design of this non-magnetic pressure cell focuses on in situ pressure tuning and measurement by means of a helium-filled bellows actuator and fiber-coupled ruby fluorescence spectroscopy, respectively. We demonstrate the utility of this pressure cell with ac susceptibility measurements of superconducting, ferromagnetic, and antiferromagnetic phase transitions to pressures exceeding 8 GPa. This cell provides an opportunity to probe charge and magnetic order continuously and with high resolution in the three-dimensional Magnetic Field-Pressure-Temperature parameter space.

  10. A compact bellows-driven diamond anvil cell for high-pressure, low-temperature magnetic measurements

    SciTech Connect

    Feng, Yejun; Silevitch, D. M.; Rosenbaum, T. F.

    2014-03-15

    We present the design of an efficient bellows-controlled diamond anvil cell that is optimized for use inside the bores of high-field superconducting magnets in helium-3 cryostats, dilution refrigerators, and commercial physical property measurement systems. Design of this non-magnetic pressure cell focuses on in situ pressure tuning and measurement by means of a helium-filled bellows actuator and fiber-coupled ruby fluorescence spectroscopy, respectively. We demonstrate the utility of this pressure cell with ac susceptibility measurements of superconducting, ferromagnetic, and antiferromagnetic phase transitions to pressures exceeding 8 GPa. This cell provides an opportunity to probe charge and magnetic order continuously and with high resolution in the three-dimensional Magnetic Field–Pressure–Temperature parameter space.

  11. Time-Resolved Synchrotron X-ray Diffraction on Pulse Laser Heated Iron in Diamond Anvil Cell

    SciTech Connect

    Yoo, C S; Wei, H; Dias, R; Shen, G; Smith, J; Chen, J Y; Evans, W

    2011-09-21

    The authors present time-resolved synchrotron x-ray diffraction to probe the {var_epsilon}-{delta} phase transition of iron during pulse-laser heating in a diamond anvil cell. The system utilizes a monochromatic synchrotron x-ray beam, a two-dimensional pixel array x-ray detector and a dual beam, double side laser-heating system. Multiple frames of the diffraction images are obtained in real-time every 22 ms over 500 ms of the entire pulse heating period. The results show the structural evolution of iron phases at 17 GPa, resulting in thermal expansion coefficient 1/V({Delta}V/{Delta}T){sub p} = 7.1 * 10{sup -6}/K for {var_epsilon}-Fe and 2.4 * 10{sup -5}/K for {gamma}-Fe, as well as the evidence for metastability of {gamma}-Fe at low temperatures below the {var_epsilon}-{gamma} phase boundary.

  12. Velocity of sound and equations of state for methanol and ethanol in a diamond-anvil cell.

    PubMed

    Brown, J M; Slutsky, L J; Nelson, K A; Cheng, L T

    1988-07-01

    The adaptability of laser-induced phonon spectroscopy to the determination of acoustic velocity and the equation of state in the diamond-anvil high-pressure cell is demonstrated. The technique provides a robust method for measurements at high pressure in both solids and liquids so that important problems in high-pressure elasticity and the earth sciences are now tractable. The velocity of sound and the density of methanol at 25 degrees C have been measured up to a pressure of 6.8 gigapascals. These results imply a higher density (by approximately 5 percent) for liquid methanol above 2.5 gigapascals than that given in existing compilations. The adiabatic bulk modulus increases by a factor of 50 at a maximum compression of 1.8. The thermodynamic Grüneisen parameters of methanol and ethanol both increase with increasing pressure, in contrast to the behavior of most solids. PMID:17815540

  13. Sub-Kelvin magnetic and electrical measurements in a diamond anvil cell with in-situ tunability

    DOE PAGESBeta

    Palmer, Alexander; Silevitch, Daniel; Feng, Yejun; Wang, Yishu; Jaramillo, R.; Banerjee, Arnab; Ren, Yang; Rosenbaum, Thomas F.

    2015-09-04

    We discuss techniques for performing continuous measurements across a wide range of pressure-field-temperature phase space, combining the milli-Kelvin temperatures of a helium dilution refrigerator with that of the giga-Pascal pressures of a diamond anvil cell and the Tesla magnetic fields of a superconducting magnet. With a view towards minimizing remnant magnetic fields and background magnetic susceptibility, we then characterize high-strength superalloy materials for the pressure cell assembly, which allows high fidelity measurements of low-field phenomena such as superconductivity below 100 mK at pressures above 10 GPa. In situ tunability and measurement of the pressure permit experiments over a wide rangemore » of pressure, while at the same time making possible precise steps across abrupt phase transitions such as that from insulator to metal.« less

  14. Virtual Environment User Interfaces to Support RLV and Space Station Simulations in the ANVIL Virtual Reality Lab

    NASA Technical Reports Server (NTRS)

    Dumas, Joseph D., II

    1998-01-01

    Several virtual reality I/O peripherals were successfully configured and integrated as part of the author's 1997 Summer Faculty Fellowship work. These devices, which were not supported by the developers of VR software packages, use new software drivers and configuration files developed by the author to allow them to be used with simulations developed using those software packages. The successful integration of these devices has added significant capability to the ANVIL lab at MSFC. In addition, the author was able to complete the integration of a networked virtual reality simulation of the Space Shuttle Remote Manipulator System docking Space Station modules which was begun as part of his 1996 Fellowship. The successful integration of this simulation demonstrates the feasibility of using VR technology for ground-based training as well as on-orbit operations.

  15. The Effect of By-pass Current on the Accuracy of Resistivity Measurement in a Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Peng, Gang; Liu, Cai-Long; Lu, Han; Han, Yong-Hao; Gao, Chun-Xiao

    2013-06-01

    We report a quantitative analysis of by-pass current effect on the accuracy of resistivity measurement in a diamond anvil cell. Due to the by-pass current, the sample resistivity calculated by the van der Pauw method is obviously smaller than the actual value and the problem becomes more serious for a high-resistivity sample. For the consideration of high accuracy of resistivity measurement, a method is presented that the inside wall of the sample chamber should be covered by a polymethylmethane layer. With this highly insulating layer, the by-pass current is effectively prevented and the current density distribution inside the sample is very close to the ideal case.

  16. Cryogenic gas loading in a Mao-Bell-type diamond anvil cell for high pressure-high temperature investigations

    NASA Astrophysics Data System (ADS)

    Sekar, M.; Kumar, N. R. Sanjay; Sahu, P. Ch.; Chandra Shekar, N. V.; Subramanian, N.

    2008-07-01

    A simple system for loading argon fluid at cryogenic temperatures in a Mao-Bell-type diamond anvil cell (DAC) has been developed. It is done in a two step process in which the piston-cylinder assembly alone is submerged in the cryogenic chamber for trapping the liquefied inert gas. Liquid nitrogen is used for condensing the argon gas. This system is now being efficiently used for loading liquid argon in the DAC for high pressure-high temperature experiments. The success rate of trapping liquefied argon in the sample chamber is about 75%. The performance of the gas loading system is successfully tested by carrying out direct conversion of pyrolitic graphite to diamond under high pressure-high temperature using laser heated DAC facility.

  17. Hierarchical Multiscale Framework for Materials Modeling: Advances in Scale-Bridging Applied to a Taylor Anvil Impact Test of RDX

    NASA Astrophysics Data System (ADS)

    Barnes, Brian; Leiter, Kenneth; Becker, Richard; Knap, Jaroslaw; Brennan, John

    As part of a multiscale modeling effort, we present progress on a challenge in continuum-scale modeling: the direct incorporation of complex molecular-level processes in the constitutive evaluation. In this initial phase of the research we use a concurrent scale-bridging approach, with a hierarchical multiscale framework running in parallel to couple a particle-based model (the ''lower scale'') computing the equation of state (EOS) to the constitutive response in a finite-element multi-physics simulation (the ''upper scale''). The lower scale simulations of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) use a force-matched coarse-grain model and dissipative particle dynamics methods, and the upper scale simulation is of a Taylor anvil impact experiment. Results emphasize use of adaptive sampling (via dynamic kriging) that accelerates time to solution, and its comparison to fully ''on the fly'' runs. Work towards inclusion of a fully reactive EOS is also discussed.

  18. Diamond-anvil cell observations of a new methane hydrate phase in the 100-MPa pressure range

    USGS Publications Warehouse

    Chou, I.-Ming; Sharma, A.; Burruss, R.C.; Hemley, R.J.; Goncharov, A.F.; Stern, L.A.; Kirby, S.H.

    2001-01-01

    A new high-pressure phase of methane hydrate has been identified based on its high optical relief, distinct pressure-temperature phase relations, and Raman spectra. In-situ optical observations were made in a hydrothermal diamond-anvil cell at temperatures between -40?? and 60 ??C and at pressures up to 900 MPa. Two new invariant points were located at -8.7 ??C and 99 MPa for the assemblage consisting of the new phase, structure I methane hydrate, ice Ih, and water, and at 35.3 ??C and 137 MPa for the new phase-structure I methane hydrate-water-methane vapor. Existence of the new phase is critical for understanding the phase relations among the hydrates at low to moderate pressures, and may also have important implications for understanding the hydrogen bonding in H2O and the behavior of water in the planetary bodies, such as Europa, of the outer solar system.

  19. BOLIVAR and GULFREX MCS Data Constrain Closure of the Grenada Backarc Basin During Oblique Collision Between the Lesser Antilles Arc System and Northern South America

    NASA Astrophysics Data System (ADS)

    Aitken, T. J.; Mann, P.; Christeson, G.

    2004-12-01

    The Lesser Antilles evolved from the mid-Cretaceous as an extensional arc system formed above a steeply dipping slab of Atlantic oceanic crust. The arc became extensional during the Paleocene - early Eocene along normal faults at the eastern edge of the basin as the present-day Lesser Antilles chain rifted away from the Aves Ridge. Backarc rifting ceased during the early Eocene, leaving the 140 km wide 3 km deep Grenada backarc basin. Sediment accumulation reached nearly 8 km during the Paleogene with another 1.5 km of sediments accumulating during the Neogene. In this presentation, we combine newly acquired MCS lines from the BOLIVAR study with existing GULFREX data collected in 1975 to document the structural and stratigraphic effects of closure of the Grenada backarc basin because of the progressive, oblique collision between the Lesser Antilles arc system and northern South America. The southern end of the Grenada basin has been narrowed from an undeformed width of approximately 100 km to a deformed width of 30 km, and rotated nearly 90 degrees to the west as the arc system obliquely collides with the South American margin. Shortening of the colliding backarc basin is mainly accommodated by inversion of Paleogene normal faults on the eastern edge of the basin, folding, low-angle thrust faults, and possibly shale diapirism. We propose that this closure in the area is a backthrusting response during Oligocene - late Miocene closure along the leading edge of the oblique arc-continent collision in the Eastern Venezuelan basin.

  20. Estimating shallow water sound power levels and mitigation radii for the R/V Marcus G. Langseth using an 8 km long MCS streamer

    NASA Astrophysics Data System (ADS)

    Crone, Timothy J.; Tolstoy, Maya; Carton, Helene

    2014-10-01

    seismic surveys in shallow-water environments, the complexity of local geology and seafloor topography can make it difficult to accurately predict associated sound levels and establish appropriate mitigation radii required to ensure the safety of local marine protected species. This is primarily because necessary detailed information regarding the local seafloor topography and subseafloor geology is often unavailable before a survey begins. One potential solution to this problem is to measure received levels using the ship's multichannel seismic (MCS) streamer, which could allow for the dynamic real-time determination of sound levels and mitigation radii while a survey is underway. We analyze R/V Langseth streamer data collected on the shelf and slope near the Washington coast during the Cascadia Open-Access Seismic Transects (COAST) and Ridge2Trench projects to measure received levels up to a distance of approximately 8 km from the sound source array. We establish methods to filter, clean, and process streamer data to accurately determine received power levels and confidently establish mitigation radii. We show that in shallow water measured power levels can fluctuate due to the influence of seafloor topographic features, but that the use of the streamer for the establishment of dynamic mitigation radii is feasible and should be further pursued. The establishment of mitigation radii based on local conditions may help to maximize the safety of marine protected species while also maximizing the ability of researchers to conduct seismic studies.

  1. Metal-Silicate Partitioning of Various Siderophile Elements at High Pressure and High Temperatures: a Diamond Anvil Cell Study

    NASA Astrophysics Data System (ADS)

    Badro, J.; Blanchard, I.; Siebert, J.

    2015-12-01

    Core formation is the major chemical fractionation that occurred on Earth. This event is widely believed to have happened at pressures of at least 40 GPa and temperatures exceeding 3000 K. It has left a significant imprint on the chemistry of the mantle by removing most of the siderophile (iron-loving) elements from it. Abundances of most siderophile elements in the bulk silicate Earth are significantly different than those predicted from experiments at low P-T. Among them, vanadium, chromium, cobalt and gallium are four siderophile elements which abundances in the mantle have been marked by core formation processes. Thus, understand their respective abundance in the mantle can help bringing constraints on the conditions of Earth's differentiation. We performed high-pressure high-temperature experiments using laser heating diamond anvil cell to investigate the metal-silicate partitioning of those four elements. Homogeneous glasses doped in vanadium, chromium, cobalt and gallium were synthesized using a levitation furnace and load inside the diamond anvil cell along with metallic powder. Samples were recovered using a Focused Ion Beam and chemically analyzed using an electron microprobe. We investigate the effect of pressure, temperature and metal composition on the metal-silicate partitioning of V, Cr, Co and Ga. Three previous studies focused on V, Cr and Co partitioning at those conditions of pressure and temperature, but none explore gallium partitioning at the relevant extreme conditions of core formation. We will present the first measurements of gallium metal-silicate partitioning performed at the appropriate conditions of pressure and temperature of Earth's differentiation.

  2. Numerical analysis of stress distribution in Cu-stabilized GdBCO CC tapes during anvil tests for the evaluation of transverse delamination strength

    NASA Astrophysics Data System (ADS)

    Dizon, John Ryan C.; Gorospe, Alking B.; Shin, Hyung-Seop

    2014-05-01

    Rare-earth-Ba-Cu-O (REBCO) based coated conductors (CCs) are now being used for electric device applications. For coil-based applications such as motors, generators and magnets, the CC tape needs to have robust mechanical strength along both the longitudinal and transverse directions. The CC tape in these coils is subjected to transverse tensile stresses during cool-down and operation, which results in delamination within and between constituent layers. In this study, in order to explain the behaviour observed in the evaluation of c-axis delamination strength in Cu-stabilized GdBCO CC tapes by anvil tests, numerical analysis of the mechanical stress distribution within the CC tape has been performed. The upper anvil size was varied in the analysis to understand the effect of anvil size on stress distribution within the multilayered CC tape, which is closely related to the delamination strength, delamination mode and delamination sites that were experimentally observed. The numerical simulation results showed that, when an anvil size covering the whole tape width was used, the REBCO coating film was subjected to the largest stress, which could result in low mechanical delamination and electromechanical delamination strengths. Meanwhile, when smaller-sized anvils were used, the copper stabilizer layer would experience the largest stress among all the constituent layers of the CC tape, which could result in higher mechanical and electromechanical delamination strengths, as well as high scattering of both of these delamination strengths. As a whole, the numerical simulation results could explain the damage evolution observed in CC tapes tested under transverse tensile stress, as well as the transverse tensile stress response of the critical current, Ic.

  3. Simplified manual fabrication of cubic-zirconia gem anvils for extended energy-range spectroscopic studies to routine high pressures of 100-150 kbar (10-15 GPa)

    NASA Astrophysics Data System (ADS)

    Jackson, N. R.; Erasmus, R. M.; Hearne, G. R.

    2010-07-01

    Methodology has been developed so as to attain routine extreme conditions as high as 10-15 GPa in a gem anvil optical pressure cell using hand (manual) processed gem anvils. The anvils polished by a simplified hand held tool are inexpensive single crystal cubic zirconia (CZ) gems that have various optical advantages over diamond anvils. Appreciable pressures are attained with culet and corresponding sample cavity dimensions that are relatively convenient to load with sample material. Some technical details are provided as regards the simplified manual fabrication process, thus emphasizing the relative ease and cost effectiveness of the hand polishing technique for fabricating such high pressure anvils. Raman spectroscopy measurements, in triple subtractive mode with a confocal pinhole geometry, are used to exemplify the usefulness of the CZ gem anvil cell methodology in pressure tuning experiments. This is particularly convenient for conventional low wave-number (lattice mode regime) Raman high pressure studies, which have not been reported previously in this context. Various other applications of such anvils are suggested.

  4. African-Americans and Alzheimer's

    MedlinePlus

    ... Share Plus on Google Plus African-Americans and Alzheimer's alz.org | IHaveAlz Introduction 10 Warning Signs Brain ... African-Americans are at a higher risk for Alzheimer's disease. Many Americans dismiss the warning signs of ...

  5. Crustal thickness from 3D MCS data collected over the fast-spreading East Pacific Rise at 9°50'N

    NASA Astrophysics Data System (ADS)

    Aghaei, O.; Nedimović, M. R.; Canales, J.; Carton, H. D.; Carbotte, S. M.; Mutter, J. C.

    2011-12-01

    We compute, analyze and present crustal thickness variations for a section of the fast-spreading East Pacific Rise (EPR). The area of 3D coverage is between 9°38'N and 9°58' N (~1000 km2), where the documented eruptions of 1990-91 and 2005-06 occurred. The crustal thickness is computed by depth converting the two-way reflection travel times from the seafloor to the Moho. The seafloor and Moho reflections are picked on the migrated stack volume produced from the 3D multichannel seismic (MCS) data collected on R/V Marcus G. Langseth in summer of 2008 during cruise MGL0812. The crustal velocities used for depth conversion were computed by Canales et al. (2003; 2011) by simultaneous inversion of seismic refractions and wide-angle Moho reflection traveltimes from four ridge-parallel and one ridge-perpendicular ocean bottom seismometer (OBS) profile for which data were collected during the 1998 UNDERSHOOT experiment. The MCS data analysis included 1D and 2D filtering, offset-dependent spherical divergence correction, surface-consistent amplitude correction, common midpoint (CMP) sort with flex binning, velocity analysis, normal moveout, and CMP stretch mute. The poststack processing includes seafloor multiple mute and 3D Kirchhoff poststack time migration. Here we use the crustal thickness and Moho seismic signature variations to detail their relationship with ridge segmentation, crustal age, bathymetry, and on- and off-axis magmatism. On the western flank (Pacific plate) from 9°41' to 9°48', the Moho reflection is strong. From 9°48' to 9°52', the Moho reflection varies from moderate to weak and disappears from ~3 km to ~9 km from the ridge axis. On the eastern flank (Cocos plate) from 9°41' to 9°51', the Moho reflection varies from strong to moderate. From 9°51' to 9°54' the Moho reflection varies from moderate to weak and disappears beneath a region ~3 km to ~9 km from the axis. On the Cocos plate, across-axis crustal thickness variations (5.5-6.2 km) show a

  6. The Struggles over African Languages

    ERIC Educational Resources Information Center

    Maseko, Pam; Vale, Peter

    2016-01-01

    In this interview, African Language expert Pam Maseko speaks of her own background and her first encounter with culture outside of her mother tongue, isiXhosa. A statistical breakdown of South African languages is provided as background. She discusses Western (originally missionary) codification of African languages and suggests that this approach…

  7. Psychological Misdiagnosis of African Americans.

    ERIC Educational Resources Information Center

    Garretson, Deborah J.

    1993-01-01

    Reviews historical and current problems with making accurate psychological diagnoses of African Americans. Suggests that misdiagnosis is strongly related to pathologization of African-American culture itself. Explores diagnostic process, stereotypes of African-American psychopathology, cultural differences in values and life stressors, and…

  8. Extensive MRO CRISM Observations of 1.27 micron O2 Airglow in Mars Polar Night and Their Comparison to MRO MCS Temperature Profiles and LMD GCM Simulations

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd; Sandor, Brad J.; Wolff, Michael J.; Smith, Michael Doyle; Lefevre, Franck; Madeleine, Jean-Baptiste; Forget, Francois; Murchie, Scott L.; Seelos, Frank P.; Seelos, Kim D.; Nair, Hari A.; Toigo, Anthony D.; Humm, David; Kass, David M.; Kleinbahl, Armin; Heavens, Nicholas

    2012-01-01

    The Martian polar night distribution of 1.27 micron (0-0) band emission from O2 singlet delta [O2(1Delta(sub g))] is determined from an extensive set of Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectral Mapping (CRISM) limb scans observed over a wide range of Mars seasons, high latitudes, local times, and longitudes between 2009 and 2011. This polar nightglow reflects meridional transport and winter polar descent of atomic oxygen produced from CO2 photodissociation. A distinct peak in 1.27 micron nightglow appears prominently over 70-90NS latitudes at 40-60 km altitudes, as retrieved for over 100 vertical profiles of O2(1Delta(sub g)) 1.27 micron volume emission rates (VER). We also present the first detection of much (x80+/-20) weaker 1.58 micron (0-1) band emission from Mars O2(1Delta(sub g)). Co-located polar night CRISM O2(1Delta(sub g)) and Mars Climate Sounder (MCS) (McCleese et al., 2008) temperature profiles are compared to the same profiles as simulated by the Laboratoire de Météorologie Dynamique (LMD) general circulation/photochemical model (e.g., Lefèvre et al., 2004). Both standard and interactive aerosol LMD simulations (Madeleine et al., 2011a) underproduce CRISM O2(1Delta(sub g)) total emission rates by 40%, due to inadequate transport of atomic oxygen to the winter polar emission regions. Incorporation of interactive cloud radiative forcing on the global circulation leads to distinct but insufficient improvements in modeled polar O2(1Delta(sub g)) and temperatures. The observed and modeled anti-correlations between temperatures and 1.27 mm band VER reflect the temperature dependence of the rate coefficient for O2(1Delta(sub g)) formation, as provided in Roble (1995).

  9. Narcolepsy in African Americans

    PubMed Central

    Kawai, Makoto; O'Hara, Ruth; Einen, Mali; Lin, Ling; Mignot, Emmanuel

    2015-01-01

    Study Objectives: Although narcolepsy affects 0.02–0.05% of individuals in various ethnic groups, clinical presentation in different ethnicities has never been fully characterized. Our goal was to study phenotypic expression across ethnicities in the United States. Design/Setting: Cases of narcolepsy from 1992 to 2013 were identified from searches of the Stanford Center for Narcolepsy Research database. International Classification of Sleep Disorders, Third Edition diagnosis criteria for type 1 and type 2 narcolepsy were used for inclusion, but subjects were separated as with and without cataplexy for the purpose of data presentation. Information extracted included demographics, ethnicity and clinical data, HLA-DQB1*06:02, polysomnography (PSG), multiple sleep latency test (MSLT) data, and cerebrospinal fluid (CSF) hypocretin-1 level. Patients: 182 African-Americans, 839 Caucasians, 35 Asians, and 41 Latinos with narcolepsy. Results: Sex ratio, PSG, and MSLT findings did not differ across ethnicities. Epworth Sleepiness Scale (ESS) score was higher and age of onset of sleepiness earlier in African Americans compared with other ethnicities. HLA-DQB1*06:02 positivity was higher in African Americans (91.0%) versus others (76.6% in Caucasians, 80.0% in Asians, and 65.0% in Latinos). CSF hypocretin-1 level, obtained in 222 patients, was more frequently low (≤ 110 pg/ml) in African Americans (93.9%) versus Caucasians (61.5%), Asians (85.7%) and Latinos (75.0%). In subjects with low CSF hypocretin-1, African Americans (28.3%) were 4.5 fold more likely to be without cataplexy when compared with Caucasians (8.1%). Conclusions: Narcolepsy in African Americans is characterized by earlier symptom onset, higher Epworth Sleepiness Scale score, higher HLA-DQB1*06:02 positivity, and low cerebrospinal fluid hypocretin-1 level in the absence of cataplexy. In African Americans, more subjects without cataplexy have type 1 narcolepsy. Citation: Kawai M, O'Hara R, Einen M, Lin L

  10. The Genetic Structure and History of Africans and African Americans

    PubMed Central

    Tishkoff, Sarah A.; Reed, Floyd A.; Friedlaender, Françoise R.; Ehret, Christopher; Ranciaro, Alessia; Froment, Alain; Hirbo, Jibril B.; Awomoyi, Agnes A.; Bodo, Jean-Marie; Doumbo, Ogobara; Ibrahim, Muntaser; Juma, Abdalla T.; Kotze, Maritha J.; Lema, Godfrey; Moore, Jason H.; Mortensen, Holly; Nyambo, Thomas B.; Omar, Sabah A.; Powell, Kweli; Pretorius, Gideon S.; Smith, Michael W.; Thera, Mahamadou A.; Wambebe, Charles; Weber, James L.; Williams, Scott M.

    2010-01-01

    Africa is the source of all modern humans, but characterization of genetic variation and of relationships among populations across the continent has been enigmatic. We studied 121 African populations, four African American populations, and 60 non-African populations for patterns of variation at 1327 nuclear microsatellite and insertion/deletion markers. We identified 14 ancestral population clusters in Africa that correlate with self-described ethnicity and shared cultural and/or linguistic properties. We observed high levels of mixed ancestry in most populations, reflecting historical migration events across the continent. Our data also provide evidence for shared ancestry among geographically diverse hunter-gatherer populations (Khoesan speakers and Pygmies). The ancestry of African Americans is predominantly from Niger-Kordofanian (~71%), European (~13%), and other African (~8%) populations, although admixture levels varied considerably among individuals. This study helps tease apart the complex evolutionary history of Africans and African Americans, aiding both anthropological and genetic epidemiologic studies. PMID:19407144

  11. 3D mapping of chemical distribution from melting at lower mantle conditions in the laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Dorfman, S. M.; Nabiei, F.; Cantoni, M.; Badro, J.; Gaal, R.; Gillet, P.

    2014-12-01

    The laser-heated diamond anvil cell is a unique tool for subjecting materials to pressures over few hundreds of GPa and temperatures of thousands of Kelvins which enables us to experimentally simulate the inaccessible interiors of planets. However, small sample size, laser profile and thermally conductive diamonds cause temperature gradients of 1000s K over a few microns which also affects chemical and structural distribution of phases in the sample. We have examined samples of San Carlos olivine (Mg,Fe)2SiO3 powder melted in the diamond anvil cell by double-sided and single-sided laser heating for 3-6 minutes to ~3000 K at 35-37 GPa. Moreover, MgO is used as an insulating media in one of the sample. Recovered samples were analyzed by a combination of focused ion beam (FIB) and scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) detector. Images and chemical maps were acquired for ~300 slices with ~70 nm depth from each sample, comprising about half of the heated zone. Detailed chemical and structural analysis by transmission electron microscopy (TEM) of lamellas prepared from the remaining section of the samples will also be presented. In all samples the heated zone included (Mg,Fe)SiO3 perovskite-structured bridgmanite (PV) phase and two (Mg, Fe)O phases, one of which, magnesiowüstite (MW), is richer in iron than the other one, ferropericlase (FP). In double-side heated samples we observe a Fe-rich quenched melt core surrounded by MW phase. Our results show that with increasing heating time, Fe migrates to the molten center of the sample. In the single-side heated sample, the Fe-rich MW phase is concentrated in the center of heated zone. In all samples a FP crust was observed around the heated zone. This crust, however, is broken in the upper part (colder part) of the single-side heated sample due the high asymmetrical temperature gradient within the sample. The results confirm the importance of double-side heating and insulating media

  12. The Other African Americans.

    ERIC Educational Resources Information Center

    Matory, J. Lorand

    Black North America is ethnically and culturally diverse. It contains many groups who do not call themselves or have not always called themselves "Negro,""Black,""African-American," and so forth, such as Louisiana Creoles of color and many of the Indian tribes east of the Mississippi. There are also numerous North American ethnic groups of African…

  13. African American rhinoplasty.

    PubMed

    Boyette, Jennings R; Stucker, Fred J

    2014-08-01

    Rhinoplasty in patients of African descent requires a patient-specific approach, because the goals and ideal proportions differ from the white nose. This article discusses approaches to surgical correction of common anatomic variations. In addition, common pitfalls are outlined. PMID:25049123

  14. Elective: African Literature.

    ERIC Educational Resources Information Center

    Jenkins, Kenneth V.

    The make-up of a course in African literature for high school students is discussed. It is pointed out that the course can be constructed on already familiar lines. High school students will be able to describe clearly, for example, the relationship between environment and character or the dilemma of characters caught between traditional values…

  15. Effect of Shear Strain on the α-ε Phase Transition of Iron: a New Approach in the Rotational Diamond Anvil Cell

    SciTech Connect

    Ma,Y.; Selvi, E.; Levitas, V.; Hashemi, J.

    2006-01-01

    The effect of shear strain on the iron {alpha}-{var_epsilon} phase transformation has been studied using a rotational diamond anvil cell (RDAC). The initial transition is observed to take place at the reduced pressure of 10.8 GPa under pressure and shear operation. Complete phase transformation was observed at 15.4 GPa. The rotation of an anvil causes limited pressure elevation and makes the pressure distribution symmetric in the sample chamber before the phase transition. However, it causes a significant pressure increase at the center of the sample and brings about a large pressure gradient during the phase transformation. The resistance to the phase interface motion is enhanced due to strain hardening during the pressure and shear operations on iron and this further increases the transition pressure. The work of macroscopic shear stress and the work of the pressure and shear stress at the defect tips account for the pressure reduction of the iron phase transition.

  16. Vibrational mode Fourier Transform Spectroscopy with a diamond anvil cell: Modes of the Si DX center and S related centers in GaAs

    SciTech Connect

    Wolk, J.A.; Haller, E.E. |; Heyman, J.N.; Jeanloz, R.; Beeman, J.W.; Guitron, J.G.; Bourret, E.D.; Walukiewicz, W.W.

    1992-12-31

    The authors report the first use of the diamond anvil cell to observe the local modes of impurities in GaAs under large hydrostatic pressure by Fourier Transform Spectroscopy. These observations were accomplished by constructing a monolithic assembly which has a light concentrating cone in front of the diamond anvil cell and a Ge:Be photoconductor detector designed to operate at low photon fluxes mounted directly behind the cell. This technique has been used to discover a local vibrational mode of the DX center in GaAs:Si and, in combination with Hall effect and resistivity analysis, to infer that the charge state of this defect is negative. This new spectroscopic tool has also been used to identify new LVMs in heavily doped GaAs:S which are due to sulfur related centers.

  17. African Ancestry Is Associated with Asthma Risk in African Americans

    PubMed Central

    Pino-Yanes, María; Wade, Michael S.; Pérez-Méndez, Lina; Kittles, Rick A.; Wang, Deli; Papaiahgari, Srinivas; Ford, Jean G.; Kumar, Rajesh; Garcia, Joe G. N.

    2012-01-01

    Background Asthma is a common complex condition with clear racial and ethnic differences in both prevalence and severity. Asthma consultation rates, mortality, and severe symptoms are greatly increased in African descent populations of developed countries. African ancestry has been associated with asthma, total serum IgE and lower pulmonary function in African-admixed populations. To replicate previous findings, here we aimed to examine whether African ancestry was associated with asthma susceptibility in African Americans. In addition, we examined for the first time whether African ancestry was associated with asthma exacerbations. Methodology/Principal Findings After filtering for self-reported ancestry and genotype data quality, samples from 1,117 self-reported African-American individuals from New York and Baltimore (394 cases, 481 controls), and Chicago (321 cases followed for asthma exacerbations) were analyzed. Genetic ancestry was estimated based on ancestry informative markers (AIMs) selected for being highly divergent among European and West African populations (95 AIMs for New York and Baltimore, and 66 independent AIMs for Chicago). Among case-control samples, the mean African ancestry was significantly higher in asthmatics than in non-asthmatics (82.0±14.0% vs. 77.8±18.1%, mean difference 4.2% [95% confidence interval (CI):2.0–6.4], p<0.0001). This association remained significant after adjusting for potential confounders (odds ratio: 4.55, 95% CI: 1.69–12.29, p = 0.003). African ancestry failed to show an association with asthma exacerbations (p = 0.965) using a model based on longitudinal data of the number of exacerbations followed over 1.5 years. Conclusions/Significance These data replicate previous findings indicating that African ancestry constitutes a risk factor for asthma and suggest that elevated asthma rates in African Americans can be partially attributed to African genetic ancestry. PMID:22235241

  18. Experimental Investigation of Magnetic Superconducting and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures using Designer Diamond Anvils

    SciTech Connect

    Maple, M. Brian; Jeffries, Jason R.; Ho, Pei-Chun; Butch, Nicholas P.

    2004-09-01

    Pressure is often used as a controlled parameter for the investigation of condensed matter systems. In particular, pressure experiments can provide valuable information into the nature of superconductivity, magnetism, and the coexistence of these two phenomena. Some f-electron, heavy-fermion materials display interesting and novel behavior at moderately low pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require ultrahigh pressure techniques, techniques that generate significantly higher pressures than conventional methods, to sufficiently explore their important properties. To that end, we have been funded to develop an ultrahigh pressure diamond anvil cell facility at the University of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena. Our goals for the first year of this grant were as follows: (a) set up and test a suitable refrigerator; (b) set up a laser and spectrometer fluorescence system to determine the pressure within the diamond anvil cell; (c) perform initial resistivity measurements at moderate pressures from room temperature to liquid helium temperatures ({approx}1K); (d) investigate f-electron materials within our current pressure capabilities to find candidate materials for high-pressure studies. During the past year, we have ordered almost all the components required to set up a diamond anvil cell facility at UCSD, we have received and implemented many of the components that have been ordered, we have performed low pressure research on several materials, and we have engaged in a collaborative effort with Sam Weir at Lawrence Livermore National Lab (LLNL) to investigate Au4V under ultrahigh pressure in a designer diamond anvil cell (dDAC). This report serves to highlight the progress we have made towards developing an ultrahigh pressure research facility at UCSD, the research performed in the past year

  19. Six-axis multi-anvil press for high-pressure, high-temperature neutron diffraction experiments.

    PubMed

    Sano-Furukawa, A; Hattori, T; Arima, H; Yamada, A; Tabata, S; Kondo, M; Nakamura, A; Kagi, H; Yagi, T

    2014-11-01

    We developed a six-axis multi-anvil press, ATSUHIME, for high-pressure and high-temperature in situ time-of-flight neutron powder diffraction experiments. The press has six orthogonally oriented hydraulic rams that operate individually to compress a cubic sample assembly. Experiments indicate that the press can generate pressures up to 9.3 GPa and temperatures up to 2000 K using a 6-6-type cell assembly, with available sample volume of about 50 mm(3). Using a 6-8-type cell assembly, the available conditions expand to 16 GPa and 1273 K. Because the six-axis press has no guide blocks, there is sufficient space around the sample to use the aperture for diffraction and place an incident slit, radial collimators, and a neutron imaging camera close to the sample. Combination of the six-axis press and the collimation devices realized high-quality diffraction pattern with no contamination from the heater or the sample container surrounding the sample. This press constitutes a new tool for using neutron diffraction to study the structures of crystals and liquids under high pressures and temperatures. PMID:25430122

  20. Six-axis multi-anvil press for high-pressure, high-temperature neutron diffraction experiments

    SciTech Connect

    Sano-Furukawa, A. Hattori, T.; Arima, H.; Yamada, A.; Tabata, S.; Kondo, M.; Nakamura, A.; Kagi, H.; Yagi, T.

    2014-11-15

    We developed a six-axis multi-anvil press, ATSUHIME, for high-pressure and high-temperature in situ time-of-flight neutron powder diffraction experiments. The press has six orthogonally oriented hydraulic rams that operate individually to compress a cubic sample assembly. Experiments indicate that the press can generate pressures up to 9.3 GPa and temperatures up to 2000 K using a 6-6-type cell assembly, with available sample volume of about 50 mm{sup 3}. Using a 6-8-type cell assembly, the available conditions expand to 16 GPa and 1273 K. Because the six-axis press has no guide blocks, there is sufficient space around the sample to use the aperture for diffraction and place an incident slit, radial collimators, and a neutron imaging camera close to the sample. Combination of the six-axis press and the collimation devices realized high-quality diffraction pattern with no contamination from the heater or the sample container surrounding the sample. This press constitutes a new tool for using neutron diffraction to study the structures of crystals and liquids under high pressures and temperatures.

  1. Sound speed and thermal property measurements of inert materials: laser spectroscopy and the diamond-anvil cell

    SciTech Connect

    Zaug, J.M.

    1997-07-01

    An indispensable companion to dynamical physics experimentation, static high-pressure diamond-anvil cell research continues to evolve, with laser diagnostic, as an accurate and versatile experimental deep planetary properties have bootstrapped each other in a process that has produced even higher pressures; consistently improved calibrations of temperature and pressure under static and dynamic conditions; and unprecedented data and understanding of materials, their elasticity, equations of state (EOS), and transport properties under extreme conditions. A collection of recent pressure and/or temperature dependent acoustic and thermal measurements and deduced mechanical properties and EOS data are summarized for a wide range of materials including H2, H2O, H2S, D2S, CO2, CH4, N2O, CH3OH,, SiO2, synthetic lubricants, PMMA, single crystal silicates, and ceramic superconductors. Room P&T sound speed measurements are presented for the first time on single crystals of beta-HMX. New high-pressure and temperature diamond cell designed and pressure calibrant materials are reviewed.

  2. Simulation of laser-generated longitudinal and shear ultrasonic waves in a diamond anvil cell by the finite element method

    NASA Astrophysics Data System (ADS)

    Feng, Wen; Yang, Dexing; Zhu, Xiangchao; Guo, Yuning; Liao, Wei

    2012-01-01

    Based on the thermoelastic theory, a numerical model of ultrasonic displacement field induced by a vertical incident pulsed laser in an aluminum film in a diamond anvil cell (DAC) is established by using the finite element method (FEM). After precisely calculating the transient temperature field distributions, the bulk ultrasonic waveforms on the rear surface of the film and the characteristics of ultrasonic displacement field with time are obtained. Then directivity patterns of laser-generated longitudinal and shear ultrasonic waves are analyzed in details. The numerical results indicate that the thermoelastic force source and the characteristics of ultrasonic directivity are strongly affected by the diamond window. The energy of longitudinal wave is concentrated near the laser incident direction, and the one of shear wave is concentrated between 30° and 60° that deflected from the laser incident direction to the excited source. These characteristics in DAC system are different from the results of free surface in thermoelastic effect, while are similar to the results of free surface in ablation effect.

  3. The effect of pressure on the kinetics of γ-anhydrite crystallization investigated by diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Liu, Chuanjiang; Zheng, Haifei; Du, Jianguo; Wang, Duojun

    2015-01-01

    The crystallization kinetics of γ-anhydrite was investigated in the temperature and pressure ranges of 373-473 K and 1094-1903 MPa using a hydrothermal diamond anvil cell (HDAC) and Raman spectroscopy. A calcium sulfate solution was formed by dissolving gypsum in water at high pressure, and γ-anhydrite crystallized due to the increasing temperature. The relationship among the reaction rate, k, the temperature, T, and the pressure, P was established as k=-1.75×10-3+1.83×10-6P+3.57×10-7T, with an R2 value of 0.943, of which the applicable range is 373 K≤T≤473 K and 1196 MPa≤P≤1903 MPa. An elevation of T or P will accelerate the crystallization rate of γ-anhydrite. The time exponent n obtained between 0.96 and 1.29 indicates that the process of crystallization should be controlled by instant nucleation on the grain boundary and diffusion controlled growth. In the process of crystallization, the volume is reduced because of the decrease of pressure, and the volume change ΔV is equal to -6.05×10-6 m3/mol. The calculated activation energy Ea is 10.7 kJ/mol, and the pre-exponential factor A is 2.27×10-2 s-1.

  4. [A new separation protocol (DRBCP-F) for automated blood component donation with the MCS 3p cell separator for collection of leukocyte depleted erythrocyte concentrates and plasma].

    PubMed

    Zeiler, T; Kretschmer, V

    1997-01-01

    Previously published studies on automated blood component donation with the MCS 3p cell separator proved fairly good quality of the collected red blood cells (RBC) and fresh frozen plasma (FFP), with the disadvantage of a low hematocrit of the filtered RBC and a high platelet contamination of the FFP (RBCP-F protocol.) The DRBCP-F protocol was designed to eliminate the above-mentioned disadvantages and to provide 1 unit of leuko-depleted (filtered) RBC, 2 units of FFP, and additionally 1 platelet concentrate (PC) from the buffy coat. Twenty automated blood component collections (2 cycles, Latham bowl at 5,500 rpm, 230 ml isotonic saline for volume balance, PAGGS-M as additive solution) were performed. The RBC were filtered in a closed system after storage at 4 degrees C for 24 h. Blood cell counts and biochemical parameters of the RBC were determined initially and after 49 days. PC were separated from buffy coat after a soft spin. The volume of the RBC amounted to 293 +/- 12 ml (mean +/- SD) with a hematocrit of 0.61 +/- 0.05 l/l. Residual leukocytes after filtration were found to be 0.04 x 10(6) +/- 0.06 per unit. After storage, the following data were obtained: hemolysis 0.38%, ATP 2.1 +/- 0.4 mumol/g Hb, 2,3-diphosphoglycerate (2,3-DPG) 1.4 +/- 0.3 mumol/g Hb, ph 6.3 +/- 0.1, potassium 6.4 mmol per unit, and LDH in the supernatant was 219 U/l. None of the RBC showed bacterial growth after 49 days. The volume of the collected FFP was 398 +/- 32 ml, with 3.4 +/- 3.5 x 10(3) residual platelets and 5 +/- 12 leukocytes per microliter. Platelet concentrates contained 90.2 +/- 32 x 10(9) platelets in 88 +/- 14 ml plasma. Automated blood donation with the DRBCP-F protocol provided RBC with very low residual leukocyte counts, adequate hematocrit and good metabolic status up to 49 days, and FFP with low platelet contamination. The platelet concentrates were even superior to those prepared from whole blood using the buffy coat method. The storable leuko-depleted RBC are

  5. Sea Level History in 3D: Early results of an ultra-high resolution MCS survey across IODP Expedition 313 drillsites

    NASA Astrophysics Data System (ADS)

    Mountain, G. S.; Kucuk, H. M.; Nedimovic, M. R.; Austin, J. A., Jr.; Fulthorpe, C.; Newton, A.; Baldwin, K.; Johnson, C.; Stanley, J. N.; Bhatnagar, T.

    2015-12-01

    Although globally averaged sea level is rising at roughly 3 mm/yr (and is accelerating), rates of local sea-level change measured at coastlines may differ from this number by a factor of two or more; at some locations, sea level may even be falling. This is due to local processes that can match or even reverse the global trend, making it clear that reliable predictions of future impacts of sea-level rise require a firm understanding of processes at the local level. The history of local sea-level change and shoreline response is contained in the geologic record of shallow-water sediments. We report on a continuing study of sea-level history in sediments at the New Jersey continental margin, where compaction and glacial isostatic adjustment are currently adding 2 mm/yr to the globally averaged rise. We collected 570 sq km of ultra-high resolution 3D MCS data aboard the R/V Langseth in June-July 2015; innovative recording and preliminary results are described by Nedimovic et al. in this same session. The goal was to provide regional context to coring and logging at IODP Exp 313 sites 27-29 that were drilled 750 m into the New Jersey shelf in 2009. These sites recovered a nearly continuous record of post-Eocene sediments from non-marine soils, estuaries, shoreface, delta front, pro-delta and open marine settings. Existing seismic data are good but are 2D high-resolution profiles at line spacings too wide to enable mapping of key nearshore features. The Langseth 3D survey used shallow towing of a tuned air gun array to preserve high frequencies, and twenty-four 50-m PCables each 12.5 apart provided 6.25 x 3.125 m common-midpoint bins along seventy-seven 50-km sail lines. With this especially dense spatial resolution of a pre-stack time migrated volume we expect to map rivers, incised valleys, barrier islands, inlets and bays, pro-delta clinoforms, tidal deltas, sequence boundaries, debris flow aprons, and more. Seismic attributes linked to sedimentary facies and

  6. A new diamond anvil cell for hydrothermal studies to 2.5 GPa and from -190 to 1200 °C

    USGS Publications Warehouse

    Bassett, William A.; Shen, A.H.; Bucknum, M.; Chou, I.-Ming

    1993-01-01

    A new style of diamond anvil cell(DAC) has been designed and built for conducting research in fluids at pressures to 2.5 GPa and temperatures from −190 to 1200 °C. The new DAC has been used for optical microscope observations and synchrotron x‐ray diffraction studies. Fringes produced by interference of laser light reflected from top and bottom anvil faces and from top and bottom sample faces provide a very sensitive means of monitoring the volume of sample chamber and for observing volume and refractive index changes in samples that have resulted from transitions and reactions. X‐ray diffraction patterns of samples under hydrothermal conditions have been made by the energy dispersive method using synchrotron radiation. The new DAC has individual heaters and individual thermocouples for the upper and lower anvils that can be controlled and can maintain temperatures with an accuracy of ±0.5 °C. Low temperatures are achieved by introducing liquid nitrogen directly into the DAC. The equation of state of H2O and the α‐β quartz transition are used to determine pressure with an accuracy of ±1% in the aqueous samples. The new DAC has been used to redetermine five isochores of H2O as well as the dehydration curves of brucite, Mg(OH)2, and muscovite, KAl2(Si3Al)O10(OH)2.

  7. Pressure estimation using the ‘diamond Raman scale’ at low pressures in diamond anvil cell experiments using a highly confocal Raman system

    NASA Astrophysics Data System (ADS)

    Fujii, Taku; Ohfuji, Hiroaki

    2015-02-01

    Pressure estimation using the frequency shift of the diamond Raman peak from the anvil culet is readily and widely used in diamond anvil cell experiments along with the conventional ruby fluorescence method. Here, we propose a modified diamond Raman scale particularly designed for pressure measurement below ~10 GPa. A series of experiments were conducted using a highly confocal Raman system and H2O, ethanol/methanol mixture and NaCl samples loaded in a rhenium gasket which was pre-indented to 40-60 or 100-110 μm thick. The result showed that the frequency of the diamond Raman peak from the anvil culet increases linearly with pressure between 1 and 13 GPa, when using a sufficiently pre-indented (40-60 μm thick) gasket. The frequency shifts are calibrated against the pressure determined by the ruby fluorescence method, which is an alternative pressure scale. In addition, a preliminary measurement at high temperature up to 575 K suggests the potential application of this method for high temperature experiments.

  8. Climatology of the African Easterly Jet and Subtropical Highs over North Africa and Arabian Peninsula and a Numerical Case Study of an Intense African Easterly Wave

    NASA Astrophysics Data System (ADS)

    Spinks, James D.

    North African climate is analyzed between 1979 and 2010 with an emphasis on August using the European Center for Medium Range Weather Forecast (ECMWF) global dataset to investigate the effects of the subtropical anticyclones over North Africa and the Arabian Peninsula on the Africa easterly jet (AEJ). It was found that the AEJ encloses a core with a local wind maximum (LWM) in both West and East Africa, in which the west LWM core has a higher zonal wind speed. The strength of both cores is distinctly different by way of thermal wind balance. The variability of these synoptic weather features is higher in East Africa. The most noticeable variability of intensity occurred with easterly waves. Maintenance of easterly waves from the Arabian Peninsula into East Africa is dependent on strong zonal gradients from the AEJ. These zonal gradients were induced by the strengthening of the subtropical highs and the presence of a westerly jet in Central Africa and south of the Arabian Peninsula. During positive ENSO periods, these systems are generally weaker while in negative periods are stronger. The origins of an intense African easterly wave (AEW) and mesoscale convective system (MCS) in August 2004 (A04) were traced back to the southern Arabian Peninsula, Asir Mountains, and Ethiopian Highlands using gridded satellite (GridSat) data, ERA-I, and the WRF-ARW model. A vorticity budget was developed to investigate the dynamics and mechanisms that contribute to the formation of A04's vorticity perturbation.

  9. Understanding traditional African healing

    PubMed Central

    MOKGOBI, M.G.

    2015-01-01

    Traditional African healing has been in existence for many centuries yet many people still seem not to understand how it relates to God and religion/spirituality. Some people seem to believe that traditional healers worship the ancestors and not God. It is therefore the aim of this paper to clarify this relationship by discussing a chain of communication between the worshipers and the Almighty God. Other aspects of traditional healing namely types of traditional healers, training of traditional healers as well as the role of traditional healers in their communities are discussed. In conclusion, the services of traditional healers go far beyond the uses of herbs for physical illnesses. Traditional healers serve many roles which include but not limited to custodians of the traditional African religion and customs, educators about culture, counselors, social workers and psychologists. PMID:26594664

  10. African horse sickness.

    PubMed

    Zientara, S; Weyer, C T; Lecollinet, S

    2015-08-01

    African horse sickness (AHS) is a devastating disease of equids caused by an arthropod-borne virus belonging to the Reoviridae family, genus Orbivirus. It is considered a major health threat for horses in endemic areas in sub-Saharan Africa. African horse sickness virus (AHSV) repeatedly caused large epizootics in the Mediterranean region (North Africa and southern Europe in particular) as a result of trade in infected equids. The unexpected emergence of a closely related virus, the bluetongue virus, in northern Europe in 2006 has raised fears about AHSV introduction into Europe, and more specifically into AHSV-free regions that have reported the presence of AHSV vectors, e.g. Culicoides midges. North African and European countries should be prepared to face AHSV incursions in the future, especially since two AHSV serotypes (serotypes 2 and 7) have recently spread northwards to western (e.g. Senegal, Nigeria, Gambia) and eastern Africa (Ethiopia), where historically only serotype 9 had been isolated. The authors review key elements of AHS epidemiology, surveillance and prophylaxis. PMID:26601437

  11. East African Rift Valley, Kenya

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This rare, cloud free view of the East African Rift Valley, Kenya (1.5N, 35.5E) shows a clear view of the Turkwell River Valley, an offshoot of the African REift System. The East African Rift is part of a vast plate fracture which extends from southern Turkey, through the Red Sea, East Africa and into Mozambique. Dark green patches of forests are seen along the rift margin and tea plantations occupy the cooler higher ground.

  12. Sea level history in 3D: Data acquisition and processing for an ultra-high resolution MCS survey across IODP Expedition 313 drillsite

    NASA Astrophysics Data System (ADS)

    Nedimovic, M. R.; Mountain, G. S.; Austin, J. A., Jr.; Fulthorpe, C.; Aali, M.; Baldwin, K.; Bhatnagar, T.; Johnson, C.; Küçük, H. M.; Newton, A.; Stanley, J.

    2015-12-01

    In June-July 2015, we acquired the first 3D/2D hybrid (short/long streamer) multichannel seismic (MCS) reflection dataset. These data were collected simultaneously across IODP Exp. 313 drillsites, off New Jersey, using R/V Langsethand cover ~95% of the planned 12x50 km box. Despite the large survey area, the lateral and vertical resolution for the 3D dataset is almost a magnitude of order higher than for data gathered for standard petroleum exploration. Such high-resolution was made possible by collection of common midpoint (CMP) lines whose combined length is ~3 times the Earth's circumference (~120,000 profile km) and a source rich in high-frequencies. We present details on the data acquisition, ongoing data analysis, and preliminary results. The science driving this project is presented by Mountain et al. The 3D component of this innovative survey used an athwartship cross cable, extended laterally by 2 barovanes roughly 357.5 m apart and trailed by 24 50-m P-Cables spaced ~12.5 m with near-trace offset of 53 m. Each P-Cable had 8 single hydrophone groups spaced at 6.25 m for a total of 192 channels. Record length was 4 s and sample rate 0.5 ms, with no low cut and an 824 Hz high cut filter. We ran 77 sail lines spaced ~150 m. Receiver locations were determined using 2 GPS receivers mounted on floats and 2 compasses and depth sensors per streamer. Streamer depths varied from 2.1 to 3.7 m. The 2D component used a single 3 km streamer, with 240 9-hydrophone groups spaced at 12.5 m, towed astern with near-trace offset of 229 m. The record length was 4 s and sample rate 0.5 ms, with low cut filter at 2 Hz and high cut at 412 Hz. Receiver locations were recorded using GPS at the head float and tail buoy, combined with 12 bird compasses spaced ~300 m. Nominal streamer depth was 4.5 m. The source for both systems was a 700 in3 linear array of 4 Bolt air guns suspended at 4.5 m towing depth, 271.5 m behind the ship's stern. Shot spacing was 12.5 m. Data analysis to

  13. Shear waves in the diamond-anvil cell reveal pressure-induced instability in (Mg,Fe)O.

    PubMed

    Jacobsen, Steven D; Spetzler, Hartmut; Reichmann, Hans J; Smyth, Joseph R

    2004-04-20

    The emerging picture of Earth's deep interior from seismic tomography indicates more complexity than previously thought. The presence of lateral anisotropy and heterogeneity in Earth's mantle highlights the need for fully anisotropic elasticity data from mineral physics. A breakthrough in high-frequency (gigahertz) ultrasound has resulted in transmission of pure-mode elastic shear waves into a high-pressure diamond-anvil cell using a P-to-S elastic-wave conversion. The full elastic tensor (c(ij)) of high-pressure minerals or metals can be measured at extreme conditions without optical constraints. Here we report the effects of pressure and composition on shear-wave velocities in the major lower-mantle oxide, magnesiowüstite-(Mg,Fe)O. Magnesiowüstite containing more than approximately 50% iron exhibits pressure-induced c(44) shear-mode softening, indicating an instability in the rocksalt structure. The oxide closer to expected lower-mantle compositions ( approximately 20% iron) shows increasing shear velocities more similar to MgO, indicating that it also should have a wide pressure-stability field. A complete sign reversal in the c(44) pressure derivative points to a change in the topology of the (Mg,Fe)O phase diagram at approximately 50-60% iron. The relative stability of Mg-rich (Mg,Fe)O and the strong compositional dependence of shear-wave velocities (and partial differential c(44)/ partial differential P) in (Mg,Fe)O implies that seismic heterogeneity in Earth's lower mantle may result from compositional variations rather than phase changes in (Mg,Fe)O. PMID:15079080

  14. Fluorescences Of Inclusion Oils With Respect To Their Maturities And Sources:Simulation In Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Chang, Y.; Huang, W.

    2007-12-01

    Evolution of fluorescence color of inclusion oils has been simulated by measuring in-situ the fluorescence of `live' oils generated from thirteen oil-prone kerogens from different depositional environments during a closed system pyrolysis in a diamond anvil cell at three heating rates (3, 8, and 25°C /min) up to 600°C. The measured fluorescence intensity of samples increases considerably within maturation intervals close to oil windows, while the fluorescence spectra of oils generated from all studied kerogens exhibit exclusively a progressive blue-shift of peak wavelengths (λmax) and red/green quotient (Q) upon increasing maturity. The observation is consistent with the maturity dependence of spectral shift trend widely recognized in natural hydrocarbon inclusions or crude oils. This study furthermore reveals that the acclaimed direction of spectral shift for inclusion oils is mostly independent of sources of their parental kerogens, implying that some reverse or anomalous trends reported in inclusion oils may be attributed to other processes subsequent to their generation, which significantly altered the fluorescence properties of oils. However, the experimental maturity corresponding to each color (λmax or Q) of oils can vary significantly (± 0.2 %Ro) among their sourced kerogens, suggesting that single fluorescence color of crude or inclusion oil is both maturity- and source-dependent and therefore may not be a good indication of its maturity. In addition, the blue-shift of cumulative oils generated from all kerogens approaches similar minima λmax around 564 nm or Q- value around 0.6 at maturity close to the middle or late stage of oil generation, implying that most late cumulative oils may exhibit similar colors. The oils generated in a maturity interval in late stage, however, can exhibit color of shorter wavelength less than the minimum.

  15. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres[reg

    SciTech Connect

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Herve; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1 MPa-2 GPa pressure range, for temperatures between ambient and 323 K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres[reg], which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5 nm line of an Ar{sup +} laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598 nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6{+-}0.2 nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93({+-}0.08) nm/GPa. The fluorescence of the FluoSpheres[reg] has been investigated as a function of pressure (0.1-4 GPa), temperature (295-343 K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1 MPa and 2 GPa, at temperatures not exceeding 323 K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P=0.100 ({+-}0.001) {delta}{lambda}{sub i}(P) with {delta}{lambda}{sub i}(P)={lambda}{sub i}(P)-{lambda}{sub i}(0) and {lambda}{sub i}(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  16. A sensitive pressure sensor for diamond anvil cell experiments up to 2 GPa: FluoSpheres®

    NASA Astrophysics Data System (ADS)

    Picard, Aude; Oger, Phil M.; Daniel, Isabelle; Cardon, Hervé; Montagnac, Gilles; Chervin, Jean-Claude

    2006-08-01

    We present an optical pressure sensor suitable for experiments in diamond anvil cell in the 0.1MPa-2GPa pressure range, for temperatures between ambient and 323K. It is based on the pressure-dependent fluorescence spectrum of FluoSpheres®, which are commercially available fluorescent microspheres commonly used to measure blood flow in experimental biology. The fluorescence of microspheres is excited by the 514.5nm line of an Ar+ laser, and the resulting spectrum displays three very intense broad bands at 534, 558, and 598nm, respectively. The reference wavelength and pressure gauge is that of the first inflection point of the spectrum, located at 525.6±0.2nm at ambient pressure. It is characterized by an instantaneous and large linear pressure shift of 9.93(±0.08)nm/GPa. The fluorescence of the FluoSpheres® has been investigated as a function of pressure (0.1-4GPa), temperature (295-343K), pH (3-12), salinity, and pressure transmitting medium. These measurements show that, for pressures comprised between 0.1MPa and 2GPa, at temperatures not exceeding 323K, at any pH, in aqueous pressure transmitting media, pressure can be calculated from the wavelength shift of two to three beads, according to the relation P =0.100 (±0.001) Δλi(P ) with Δλi(P )=λi(P)-λi(0) and λi(P) as the wavelength of the first inflection point of the spectrum at the pressure P. This pressure sensor is approximately thirty times more sensitive than the ruby scale and responds instantaneously to pressure variations.

  17. Determination of differential stress in the D-DIA using cubic BN anvils and 2-D monochromatic diffraction

    NASA Astrophysics Data System (ADS)

    Uchida, T.; Wang, Y.; Rivers, M. L.; Durham, W. B.; Mei, S.

    2003-04-01

    We have adopted X-ray transparent cubic boron nitride (cBN) anvils in a modified deformation DIA (D-DIA) to conduct monochromatic diffraction using a 2-D CCD detector (SMART1500). This setup allows us to obtain real-time diffraction data with complete Debye rings that are essential for accurate determination of lattice strains in the deformed sample. Experiments have been conducted on MgO to 6.3 GPa and 1273 K in the D-DIA. Samples were deformed continuously up to 30 percent axial shortening, with various strain rates between 0.001 and 0.00001 per second, under fixed confining pressure. Pressure, temperature, sample length, and monochromatic diffraction patterns were recorded repeatedly during the constant-strain rate deformation process. A monochromatic beam with a wavelength of 0.248 Angstrom (50 keV) was used for diffraction. We have developed a software package to analyze the 2-D diffraction data. After spatial and flat-field corrections, each 2-D diffraction pattern is converted into a multiple of 1-D patterns, according to a given azimuth angle range (typically binned at 1 degree intervals). The 1-D patterns are then fitted to yield information on the azimuth dependence for each lattice spacing. Lattice strain is then computed based on the well-known theory (A.K. Singh, J. Appl. Phys., 73, 4278, 1993) to convert to differential stress. This approach allows us to examine lattice strain as a function of pressure, temperature, and total plastic strain systematically. With the known pressure and temperature dependence of the elastic constants for MgO, differential stress can be evaluated throughout deformation. Details of the methodology and analysis will be presented and sources of experimental uncertainties will be discussed.

  18. Coupled phase transformations and plastic flows under torsion at high pressure in rotational diamond anvil cell: Effect of contact sliding

    NASA Astrophysics Data System (ADS)

    Feng, Biao; Levitas, Valery I.

    2013-12-01

    A three-dimensional large-sliding contact model coupled with strain-induced phase transformations (PTs) and plastic flow in a disk-like sample under torsion at high pressure in rotational diamond anvil cell (RDAC) is formulated and studied. Coulomb and plastic friction are combined and take into account variable parameters due to PT. Results are obtained for weaker, equal-strength, and stronger high pressure phases, and for three values of the kinetic coefficient in a strain-controlled kinetic equation and friction coefficient. All drawbacks typical of problem with cohesion are overcome, including eliminating mesh-dependent shear band and artificial plastic zones. Contact sliding intensifies radial plastic flow, which leads to larger reduction in sample thickness. Larger plastic strain and increased pressure in the central region lead to intensification of PT. However, the effect of the reduction in the friction coefficient on PT kinetics is nonmonotonous. Sliding increases away from the center and with growing rotation and is weakly dependent on the kinetic coefficient. Also, cyclic back and forth torsion is studied and compared to unidirectional torsion. Multiple experimental phenomena, e.g., pressure self-multiplication effect, steps (plateaus) at pressure distribution, flow to the center of a sample, and oscillatory pressure distribution for weaker high-pressure phase, are reproduced and interpreted. Reverse PT in high pressure phase that flowed to the low pressure region is revealed. Possible misinterpretation of experimental PT pressure is found. Obtained results represent essential progress toward understanding of strain-induced PTs under compression and shear in RDAC and may be used for designing experiments for synthesis of new high pressure phases and reduction in PT pressure for known phases, as well as for determination of PT kinetics from experiments.

  19. Shear waves in the diamond-anvil cell reveal pressure-induced instability in (Mg,Fe)O

    PubMed Central

    Jacobsen, Steven D.; Spetzler, Hartmut; Reichmann, Hans J.; Smyth, Joseph R.

    2004-01-01

    The emerging picture of Earth's deep interior from seismic tomography indicates more complexity than previously thought. The presence of lateral anisotropy and heterogeneity in Earth's mantle highlights the need for fully anisotropic elasticity data from mineral physics. A breakthrough in high-frequency (gigahertz) ultrasound has resulted in transmission of pure-mode elastic shear waves into a high-pressure diamond-anvil cell using a P-to-S elastic-wave conversion. The full elastic tensor (cij) of high-pressure minerals or metals can be measured at extreme conditions without optical constraints. Here we report the effects of pressure and composition on shear-wave velocities in the major lower-mantle oxide, magnesiowüstite-(Mg,Fe)O. Magnesiowüstite containing more than ≈50% iron exhibits pressure-induced c44 shear-mode softening, indicating an instability in the rocksalt structure. The oxide closer to expected lower-mantle compositions (≈20% iron) shows increasing shear velocities more similar to MgO, indicating that it also should have a wide pressure-stability field. A complete sign reversal in the c44 pressure derivative points to a change in the topology of the (Mg,Fe)O phase diagram at ≈50–60% iron. The relative stability of Mg-rich (Mg,Fe)O and the strong compositional dependence of shear-wave velocities (and ∂c44/∂P) in (Mg,Fe)O implies that seismic heterogeneity in Earth's lower mantle may result from compositional variations rather than phase changes in (Mg,Fe)O. PMID:15079080

  20. Effect of Laser Annealing of Common Solid Pressure Media on Pressure Gradients in a Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Uts, I.; Glazyrin, K.; Lee, K. K.

    2012-12-01

    Advances in experimental techniques allow for the studying of geophysics and planetary science related materials under high pressure and high temperature conditions. With the intrinsic limits of the multianvil apparatus, compression in a diamond anvil cell (DAC) has become the preferred method for creating the extreme conditions of planetary interiors. High pressures up to 1 Mbar can be routinely obtained in laboratories with the use of DACs. Additionally, as in situ laser heating is becoming progressively more affordable for DACs, it is becoming more common to find laser heating setups in many large scale facilities. After the sample material, the pressure medium is the second most important ingredient for a successful high pressure DAC experiment. Not every pressure medium is equally suitable for every experiment. For example, solid pressure media are more persistent than gaseous pressure media if high temperature heating is required. The melting point of the former is much higher, and melting of pressure media may induce undesirable sample shift in the pressure chamber. However, the most important characteristic of a pressure medium is its ability to maintain hydrostaticity in the DAC. The media, particularly solid pressure media, become less effective with increasing pressure. One of the most popular ways of alleviating pressure gradients is through laser annealing of the sample. We explore the effectiveness of this technique in relation to common pressure media, namely, alkali metal halides NaCl, CsCl, KCl, LiF, and oxide MgO. The samples were laser annealed at temperatures above 2000 K. Pressure gradients were determined through the analysis of diamond Raman and ruby fluorescence peaks before and after annealing the sample with a near-infrared laser. We find that the effect of annealing varies for different materials. For some (NaCl and KCl), it reduces pressure gradients considerably, but for the others (MgO), the effect of annealing is less profound.

  1. Hot pressing of polycrystals of high-pressure phases of mantle minerals in multi-anvil apparatus

    NASA Astrophysics Data System (ADS)

    Gwanmesia, Gabriel D.; Li, Baosheng; Liebermann, Robert C.

    1993-06-01

    In the 1960s, E. Schreiber and his colleagues pioneered the use of hot-pressed polycrystalline aggregates for studies of the pressure and temperature dependence of the elastic wave velocities in minerals. We have extended this work to the high-pressure polymorphs of mantle minerals by developing techniques to fabricate large polycrystalline specimens in a 2000-ton uniaxial split-sphere apparatus. A new cell assembly has been developed to extend this capability to pressures of 20 GPa and temperatures of 1700°C. Key elements in the new experimental design include: a telescopic LaCrO3 for T>1200°C; Toshiba Tungaloy grade F tungsten carbide anvils; and the use of homogeneous glasses or seeded powder mixtures as starting material to enhance reactivity and maximize densities. Cell temperatures are linearly related to electrical power to 1700°C and uniform throughout the 3 mm specimens. Pressure calibrations at 25°C and 1700°C are identical to 15 GPa. Cylindrical specimens of the beta and spinel phases of Mg2SiO4, stishovite (SiO2-rutile), and majorite-pyrope garnets have been synthesized within their stability fields in runs of 1 4 hr duration and recovered at ambient conditions by simultaneously decompressing and cooling along a computer-controlled P-T path designed to preserve the high-pressure phase and to relax intergranualar stress in the polycrystalline aggregate. These specimens are single-phased, fine-grained (<5 micron), free of microcracks and preferred orientation, and have bulk densities greater than 99% of X-ray density. The successful fabrication of these high-quality polycrystalline specimens has made possible experiments to determine the pressure dependence of acoustic velocities in the ultrasonics laboratory of S. M. Rigden and I. Jackson at the Australian National University.

  2. A Teacher's Guide to African Narratives. Studies in African Literature.

    ERIC Educational Resources Information Center

    O'Brien, Sara Talis

    This guide is designed to help secondary school teachers include African literature in their classes. It furnishes English and social studies teachers with a foundation for teaching African literature by offering critical commentary on the texts themselves. A synthesis of anthropological and historical material is presented to help both teachers…

  3. African-American Sacred Music.

    ERIC Educational Resources Information Center

    Bailey, A. Peter

    1991-01-01

    The history of African-American sacred music is traced from the time of slavery to the present interest in gospel music. The religious music of African Americans is geared toward liberation themes. It is important that this music does not dilute its power through cross-over with other music forms. (SLD)

  4. Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

    SciTech Connect

    Chou, I.-M.; Bassett, W.A.; Anderson, A.J.; Mayanovic, R.A.; Shang, L.

    2009-03-25

    Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 {micro}m in diameter and - 50 {micro}m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90{sup o} angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 {micro}m, a pressure of 76 MPa at 500 C was maintained for 2 h with no change in the original fluid density.

  5. Experimental Investigation of Magnetic Superconducting, and other Phase Transitions in Novel f-Electron Materials at Ultra-high Pressures Using Designer Diamond Anvils

    SciTech Connect

    Maple, M. Brian

    2005-09-13

    Pressure is a powerful control parameter, owing to its ability to affect crystal and electronic structure without introducing defects, for the investigation of condensed matter systems. Some f-electron, heavy-fermion materials display interesting and novel behavior when exposed to pressures achievable with conventional experimental techniques; however, a growing number of condensed matter systems require extreme conditions such as ultrahigh pressures, high magnetic fields, and ultralow temperatures to sufficiently explore the important properties. To that end, we have been funded to develop an ultrahigh pressure facility at the University of California, San Diego (UCSD) in order to investigate superconductivity, magnetism, non-Fermi liquid behavior, and other phenomena under extreme conditions. Our goals for the second year of this grant were as follows: (a) perform electrical resistivity measurements on novel samples at a myriad of pressures using conventional piston-cylinder techniques, Bridgman anvil techniques, and diamond anvil cell technology; (b) install, commission, and operate an Oxford Kelvinox MX-100 dilution refrigerator for access to ultralow temperatures and high magnetic fields. (c) continue the development of diamond anvil cell (DAC) technology. During the past year, we have successfully installed the Oxford Kelvinox MX-100 dilution refrigerator and verified its operability down to 12 mK. We have begun an experimental program to systematically investigate the f-electron compound URu2Si2 under pressure and in the presence of magnetic fields. We have also continued our collaborative work with Sam Weir at Lawrence Livermore National Laboratory (LLNL) on Au4V and implemented a new corollary study on Au1-xVx using ultrahigh pressures. We have continued developing our DAC facility by designing and constructing an apparatus for in situ pressure measurement as well as designing high pressure cells. This report serves to highlight the progress we have made

  6. Containment of fluid samples in the hydrothermal diamond-anvil cell without the use of metal gaskets: Performance and advantages for in situ analysis

    USGS Publications Warehouse

    Chou, I.-Ming; Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Shang, L.

    2008-01-01

    Metal gaskets (Re, Ir, Inconel, or stainless steel) normally used to contain fluid samples in the hydrothermal diamond-anvil cell (HDAC) are sometimes undesirable due to possible contamination and to gasket deformation at high pressures and temperatures resulting in nonisochoric behavior. Furthermore, in x-ray spectroscopic experiments, metal gaskets may attenuate the incident x-ray beam and emitted fluorescence x-rays, and the interaction of scattered radiation with the gasket may produce fluorescence that interferes with the x-ray spectrum of the sample. New arrangements and procedures were tested for the operation of the HDAC without using the metal gaskets. Distilled, de-ionized water was loaded into the sample chamber, a laser-milled recess 300 ??m in diameter and ???50 ??m deep centered in the 1.0 mm face of the lower diamond anvil, and sealed by pressing the top diamond anvil face directly against the lower one without a metal gasket in between. A maximum sample pressure of 202 MPa at 617 ??C was maintained for a duration of 10 min without evidence of leakage. A small change in fluid density was observed in one experiment where the sample was held at 266 MPa at 708 ??C for 10 min. The gasketless HDAC was also employed in x-ray absorption spectroscopy experiments, where, in addition to the sample chamber in the lower diamond, two grooves were milled at a 90?? angle to each other around the sample chamber to minimize the attenuation of incident and fluorescent x rays. With a minimum distance between the sample chamber and the grooves of 80 ??m, a pressure of 76 MPa at 500 ??C was maintained for 2 h with no change in the original fluid density. ?? 2008 American Institute of Physics.

  7. African oil plays

    SciTech Connect

    Clifford, A.J. )

    1989-09-01

    The vast continent of Africa hosts over eight sedimentary basins, covering approximately half its total area. Of these basins, only 82% have entered a mature exploration phase, 9% have had little or no exploration at all. Since oil was first discovered in Africa during the mid-1950s, old play concepts continue to bear fruit, for example in Egypt and Nigeria, while new play concepts promise to become more important, such as in Algeria, Angola, Chad, Egypt, Gabon, and Sudan. The most exciting developments of recent years in African oil exploration are: (1) the Gamba/Dentale play, onshore Gabon; (2) the Pinda play, offshore Angola; (3) the Lucula/Toca play, offshore Cabinda; (4) the Metlaoui play, offshore Libya/Tunisia; (5) the mid-Cretaceous sand play, Chad/Sudan; and (6) the TAG-I/F6 play, onshore Algeria. Examples of these plays are illustrated along with some of the more traditional oil plays. Where are the future oil plays likely to develop No doubt, the Saharan basins of Algeria and Libya will feature strongly, also the presalt of Equatorial West Africa, the Central African Rift System and, more speculatively, offshore Ethiopia and Namibia, and onshore Madagascar, Mozambique, and Tanzania.

  8. Bioenergy and African transformation.

    PubMed

    Lynd, Lee R; Sow, Mariam; Chimphango, Annie Fa; Cortez, Luis Ab; Brito Cruz, Carlos H; Elmissiry, Mosad; Laser, Mark; Mayaki, Ibrahim A; Moraes, Marcia Afd; Nogueira, Luiz Ah; Wolfaardt, Gideon M; Woods, Jeremy; van Zyl, Willem H

    2015-01-01

    Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures. PMID:25709714

  9. New Experimental Method for In Situ Determination of Material Textures at Simultaneous High-Pressure and -Temperature by Means of Radial Diffraction in the Diamond Anvil Cell.

    SciTech Connect

    Liermann, H; Merkel, S; Miyagi, L; Wenk, H; Shen, G; Cynn, H; Evans, W J

    2009-07-15

    We introduce the design and capabilities of a new resistive heated diamond anvil cell that can be used for side diffraction at simultaneous high-pressure and -temperature. The device can be used to study lattice-preferred orientations in polycrystalline samples up to temperatures of 1100 K and pressures of 36 GPa. Capabilities of the instrument are demonstrated with preliminary results on the development of textures in the BCC, FCC and HCP polymorphs of iron during a non-hydrostatic compression experiment at simultaneous high-pressure and -temperature.

  10. Preparation of W-Ta thin-film thermocouple on diamond anvil cell for in-situ temperature measurement under high pressure

    SciTech Connect

    Yang Jie; Li Ming; Zhang Honglin; Gao Chunxiao

    2011-04-15

    In this paper, a W-Ta thin-film thermocouple has been integrated on a diamond anvil cell by thin-film deposition and photolithography methods. The thermocouple was calibrated and its thermal electromotive force was studied under high pressure. The results indicate that the thermal electromotive force of the thermocouple exhibits a linear relationship with temperature and is not associated with pressure. The resistivity measurement of ZnS powders under high pressure at different temperatures shows that the phase transition pressure decreases as the temperature increases.

  11. Study of the reaction products of SF6 and C in the laser heated diamond anvil cell by pair distribution function analysis and micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rademacher, N.; Bayarjargal, L.; Morgenroth, W.; Bauer, J. D.; Milman, V.; Winkler, B.

    2015-05-01

    The decomposition of SF6 in the presence of glassy carbon was induced in laser heated diamond anvil cells at 10-11 GPa and 2000-2500 K. The reaction products were characterised by synchrotron X-ray diffraction, including high pressure pair distribution function analysis, and micro-Raman spectroscopy combined with atomistic model calculations. The decomposition leads to elemental amorphous helical sulfur and crystalline CF4-III. Two different sulfur phases, namely helical Sμ and crystalline α-S8, were observed after recovering the laser heated samples of different experiments at ambient conditions.

  12. Experimental issues in in-situ synchrotron x-ray diffraction at high pressure and temperature by using a laser-heated diamond-anvil cell

    SciTech Connect

    Yoo, C.S.

    1997-12-01

    An integrated technique of diamond-anvil cell, laser-heating and synchrotron x-ray diffraction technologies is capable of structural investigation of condensed matter in an extended region of high pressures and temperatures above 100 GPa and 3000 K. The feasibility of this technique to obtain reliable data, however, strongly depends on several experimental issues, including optical and x-ray setups, thermal gradients, pressure homogeneity, preferred orientation, and chemical reaction. In this paper, we discuss about these experimental issues together with future perspectives of this technique for obtaining accurate data.

  13. Energy dispersive X-ray diffraction in the diamond anvil, high-pressure apparatus - Comparison of synchrotron and conventional X-ray sources

    NASA Technical Reports Server (NTRS)

    Spain, I. L.; Black, D. R.

    1985-01-01

    The use of both conventional fixed-anode X-ray sources and synchrotron radiation to carry out energy-dispersive X-ray diffraction experiments at high pressure in a diamond anvil cell, is discussed. The photon flux at the sample and at the detector for the two cases are compared and the results are presented in graphs. It is shown that synchrotron radiation experiments can be performed with nearly two orders of magnitude increase in data rate if superior detectors and detector electronics are available.

  14. A Method for Selecting Software for Dynamic Event Analysis II: the Taylor Anvil and Dynamic Brazilian Tests

    SciTech Connect

    W. D. Richins; J. M. Lacy; T. K. Larson; S. R. Novascone

    2008-05-01

    fracture at the center of the specimen that propagates toward the loading points until the cylinder is split. To generate a dynamic load, different methods such as a drop-weight or a split Hopkinson pressure bar are employed. The Taylor anvil and dynamic Brazilian test analyses are presented, including discussion of the analysis approach for each of the five subject software packages; comparison of results both among the codes and to physical test results; and conclusions as to the applicability of the subject codes to these two problems. Studies of the remaining three benchmark problems and overall conclusions will be presented in future reports.

  15. Noble Gases Analyses of Samples Synthesized at High P and T in a Multi Anvil Press Device: Protocol and Implications

    NASA Astrophysics Data System (ADS)

    Bonnefoy, B.; Andrault, D.; Moreira, M.; Bolfan-Casanova, N.

    2007-12-01

    Noble gases (He-Ne-Ar-Kr-Xe) in mantle-derived samples allow an undisputable tracing of different sources of materials. Concerning the deep mantle part, the study of noble gases suggests that a "primordial" component (which is non or partially degassed) exists. Nevertheless, this conclusion is challenged by several observations, both geophysical and geochemical, suggesting that contrariwise the mantle is now totally depleted, degassed or renewed by convection. Furthermore, the lack of experimental data disables quantitative modelling of geochemistry processes. It is still unknown how much the fractionations are dependent on the conditions on pressure, temperature and chemical composition in the mantle. Recent studies [1-3] suggest a more incompatible behavior for noble gases in comparison to their parent element (K for Ar, U + Th for He) in very specific conditions of pressure, temperature, and chemical composition. Nevertheless, those studies focus on only particular compositions or pressures or only one single noble gas. No exhaustive studies (of all nobles gases at different pressures, temperatures and compositions) were accomplished on this subject so far. We set up a new experimental protocol allowing the analyses of rare gases in samples synthesized under mantle conditions, at high pressures and temperatures. This new protocol associates the use of a gas loading device [4], a multi-anvil press device (INSU MAP, Clermont-Ferrand, France), a laser ablation coupled to mass- spectrometer for the noble gases analysis (excimer laser, λ = 193 nm), and a 3D profilometry device to quantify the amount of ablated material. We will present an application of these methods on the noble gases partitioning between solid and liquid natural phases in the 3-5 GPa pressure range and for temperature of 1400 to 1600°C. [1] E.M. Chamorro, R.A Brooker, J.-A Wartho, B.J. Wodd, S.P. Kelley and J.D. Blundy. Ar and K partitioning between clinopyroxene and silicate melt to 8 GPa

  16. Assimilation Differences among Africans in America.

    ERIC Educational Resources Information Center

    Dodoo, F. Nii-Amoo

    1997-01-01

    Census data (1990) indicate that male African immigrants earn more than their Caribbean-born counterparts or native-born African Americans, but controlling for relevant earnings-related endowments erases the African advantage and elevates Caribbean earnings above those of the other groups. Also, African (but not Caribbean) university degree…

  17. Successfully Educating Our African-American Students

    ERIC Educational Resources Information Center

    Moncree-Moffett, Kareem

    2013-01-01

    The purpose of this empirical study was to explore the lived experiences of African American retired female teachers who have prior experience with educating urban African American students in public schools. Also explored are the experiences of active African American female teachers of urban African American students and comparisons are…

  18. Negro, Black, Black African, African Caribbean, African American or what? Labelling African origin populations in the health arena in the 21st century.

    PubMed

    Agyemang, Charles; Bhopal, Raj; Bruijnzeels, Marc

    2005-12-01

    Broad terms such as Black, African, or Black African are entrenched in scientific writings although there is considerable diversity within African descent populations and such terms may be both offensive and inaccurate. This paper outlines the heterogeneity within African populations, and discusses the strengths and limitations of the term Black and related labels from epidemiological and public health perspectives in Europe and the USA. This paper calls for debate on appropriate terminologies for African descent populations and concludes with the proposals that (1) describing the population under consideration is of paramount importance (2) the word African origin or simply African is an appropriate and necessary prefix for an ethnic label, for example, African Caribbean or African Kenyan or African Surinamese (3) documents should define the ethnic labels (4) the label Black should be phased out except when used in political contexts. PMID:16286485

  19. Use of a multichannel collimator for structural investigation of low-Z dense liquids in a diamond anvil cell: Validation on fluid H{sub 2} up to 5 GPa

    SciTech Connect

    Weck, Gunnar; Spaulding, Dylan; Loubeyre, Paul; Garbarino, Gaston; Mezouar, Mohamed; Ninet, Sandra; Datchi, Frederic

    2013-06-15

    We report the first application of a multichannel collimator (MCC) to perform quantitative structure factor measurements of dense low-Z fluids in a diamond anvil cell (DAC) using synchrotron x-ray diffraction. The MCC design, initially developed for the Paris-Edinburgh large volume press geometry, has been modified for use with diamond anvil cells. A good selectivity of the diffracted signal of the dense fluid sample is obtained due to a large rejection of the Compton diffusion from the diamond anvils. The signal to background ratio is significantly improved. We modify previously developed analytical techniques for quantitative measurement of the structure factor of fluids in DACs [J. H. Eggert, G. Weck, P. Loubeyre, and M. Mezouar, Phys. Rev. B 65, 174105 (2002)] to account for the contribution of the MCC. We present experimental results on liquids argon and hydrogen at 296 K to validate our method and test its limits, respectively.

  20. African swine fever.

    PubMed

    Penrith, Mary-Louise

    2009-03-01

    African swine fever (ASF) is a devastating haemorrhagic fever of pigs that causes up to 100% mortality, for which there is no vaccine. It is caused by a unique DNA virus that is maintained in an ancient cycle between warthogs and argasid ticks, making it the only known DNA arbovirus. ASF has a high potential for transboundary spread, and has twice been transported from Africa to other continents--Europe and subsequently the Caribbean and Brazil (1957, 1959) and the Caucasus (2007). It is also a devastating constraint for pig production in Africa. Research at Onderstepoort Veterinary Institute has made and is making important contributions to knowledge of this disease, focusing on the cycle in warthogs and tampans and transmission from that cycle to domestic pigs, resistance to its effects in domestic pigs, and the molecular genetic characterisation and epidemiology of the virus. PMID:19967933

  1. The African Millennium Villages

    PubMed Central

    Sanchez, Pedro; Palm, Cheryl; Sachs, Jeffrey; Denning, Glenn; Flor, Rafael; Harawa, Rebbie; Jama, Bashir; Kiflemariam, Tsegazeab; Konecky, Bronwen; Kozar, Raffaela; Lelerai, Eliud; Malik, Alia; Modi, Vijay; Mutuo, Patrick; Niang, Amadou; Okoth, Herine; Place, Frank; Sachs, Sonia Ehrlich; Said, Amir; Siriri, David; Teklehaimanot, Awash; Wang, Karen; Wangila, Justine; Zamba, Colleen

    2007-01-01

    We describe the concept, strategy, and initial results of the Millennium Villages Project and implications regarding sustainability and scalability. Our underlying hypothesis is that the interacting crises of agriculture, health, and infrastructure in rural Africa can be overcome through targeted public-sector investments to raise rural productivity and, thereby, to increased private-sector saving and investments. This is carried out by empowering impoverished communities with science-based interventions. Seventy-eight Millennium Villages have been initiated in 12 sites in 10 African countries, each representing a major agroecological zone. In early results, the research villages in Kenya, Ethiopia, and Malawi have reduced malaria prevalence, met caloric requirements, generated crop surpluses, enabled school feeding programs, and provided cash earnings for farm families. PMID:17942701

  2. Larger genetic differences within africans than between Africans and Eurasians.

    PubMed Central

    Yu, Ning; Chen, Feng-Chi; Ota, Satoshi; Jorde, Lynn B; Pamilo, Pekka; Patthy, Laszlo; Ramsay, Michele; Jenkins, Trefor; Shyue, Song-Kun; Li, Wen-Hsiung

    2002-01-01

    The worldwide pattern of single nucleotide polymorphism (SNP) variation is of great interest to human geneticists, population geneticists, and evolutionists, but remains incompletely understood. We studied the pattern in noncoding regions, because they are less affected by natural selection than are coding regions. Thus, it can reflect better the history of human evolution and can serve as a baseline for understanding the maintenance of SNPs in human populations. We sequenced 50 noncoding DNA segments each approximately 500 bp long in 10 Africans, 10 Europeans, and 10 Asians. An analysis of the data suggests that the sampling scheme is adequate for our purpose. The average nucleotide diversity (pi) for the 50 segments is only 0.061% +/- 0.010% among Asians and 0.064% +/- 0.011% among Europeans but almost twice as high (0.115% +/- 0.016%) among Africans. The African diversity estimate is even higher than that between Africans and Eurasians (0.096% +/- 0.012%). From available data for noncoding autosomal regions (total length = 47,038 bp) and X-linked regions (47,421 bp), we estimated the pi-values for autosomal regions to be 0.105, 0.070, 0.069, and 0.097% for Africans, Asians, Europeans, and between Africans and Eurasians, and the corresponding values for X-linked regions to be 0.088, 0.042, 0.053, and 0.082%. Thus, Africans differ from one another slightly more than from Eurasians, and the genetic diversity in Eurasians is largely a subset of that in Africans, supporting the out of Africa model of human evolution. Clearly, one must specify the geographic origins of the individuals sampled when studying pi or SNP density. PMID:12019240

  3. [West African childbirth traditions].

    PubMed

    Hallgren, R

    1983-11-01

    Religious and medical practices are steeped in the traditions of West African culture vis-a-vis childbirth. It is customary for delivery to occur with the woman squatting on the ground surrounded by sisters and female relatives, some of whom function as midwives. Midwives get paid only if delivery is successful. A stool is also often used in childbirth. The name given to a child in the Yoruba tribe in Nigeria has to refer to the circumstances of the individual's birth. The contact with the earth (as in the squatting position) has religious overtones--it indicates the fecundity of the earth, and the mother's contact with it. Infertility is considered the greatest tragedy in traditional African society. In Senegal, a childless woman pays a fertile one a certain sum in return for bearing her a child who would be raised as her own (this tradition is not unlike surrogate motherhood in Western countries). Men are never present at birth; however, in urban settings this practice is changing. The burial of the placenta and umbilical cord is thought to restore the woman's fertility and help heal her womb. This practice was even recorded in 19th century Sweden harkening back to heathen times. In Ghana, an infertile woman urinates on the ground where the placenta is buried in the belief that her fertility will be restored. The birth of twins is regarded as a great blessing, and as a sign of fertility; however, the inability of the mother to breast-feed both twins may result in the death of the weaker child. The harmony of nature, animals, and human beings is paramount in traditional West Africa religion and life, and undoubtedly Western culture could learn from some of these beliefs. PMID:6558064

  4. Hydrothermal studies in a new diamond anvil cell up to 10 GPa and from -190°C to 1200°C

    USGS Publications Warehouse

    Bassett, William A.; Shen, A.H.; Bucknum, M.; Chou, I.-Ming

    1993-01-01

    The new hydrothermal diamond anvil cell (HDAC) has been designed for optical microscopy and X-ray diffraction at pressures up to 10 GPa and temperatures between −190°C and 1200°C. Laser light reffected from the top and bottom anvil faces and the top and bottom solid sample faces produce interference fringes that provide a very sensitive means of monitoring the volume of sample chamber and for observing volume and refractive index changes in solid samples due to transitions and reactions. Synchrotron radiation has been used to make X-ray diffraction patterns of samples under hydrothermal conditions. Individual heaters and individual thermocouples provide temperature control with an accuracy of ±0.5°C. Liquid nitrogen directly introduced into the HDAC has been used to reduce the sample temperature to −190°C. The α-β phase boundary of quartz has been used to calculate the transition pressures from measured transition temperatures. With this method we have redetermined 5 isochores of H2O up to 850°C and 1.2 GPa at which the solution rate of the quartz became so rapid that the quartz dissolved completely before the α-β transition could be observed. When silica solutions were cooled, opal spherules and rods formed.

  5. CO Signatures in Subtropical Convective Clouds and Anvils during CRYSTAL-FACE: An Analysis of Convective Transport and Entrainment using Observations and a Cloud-Resolving Model

    NASA Technical Reports Server (NTRS)

    Lopez, Jimena P.; Fridlind, Ann M.; Jost, Hans-Juerg; Loewenstein, Max; Ackerman, Andrew S.; Campos, Teresa L.; Weinstock, Elliot M.; Sayres, David S.; Smith, Jessica B.; Pittman, Jasna V.

    2006-01-01

    Convective systems are an important mechanism in the transport of boundary layer air into the upper troposphere. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, in July 2002, was developed as a comprehensive atmospheric mission to improve knowledge of subtropical cirrus systems and their roles in regional and global climate. In situ measurements of carbon monoxide (CO), water vapor (H2Ov), and total water (H2Ot) aboard NASA's WB-57F aircraft and CO aboard the U.S. Navy's Twin Otter aircraft were obtained to study the role of convective transport. Three flights sampled convective outflow on 11, 16 and 29 July found varying degrees of CO enhancement relative to the free troposphere. A cloud-resolving model used the in situ observations and meteorological fields to study these three systems. Several methods of filtering the observations were devised here using ice water content, relative humidity with respect to ice, and particle number concentration as a means to statistically sample the model results to represent the flight tracks. A weighted histogram based on ice water content observations was then used to sample the simulations for the three flights. In addition, because the observations occurred in the convective outflow cirrus and not in the storm cores, the model was used to estimate the maximum CO within the convective systems. In general, anvil-level air parcels contained an estimated 20-40% boundary layer air in the analyzed storms.

  6. A design of backing seat and gasket assembly in diamond anvil cell for accurate single crystal x-ray diffraction to 5 GPa

    NASA Astrophysics Data System (ADS)

    Komatsu, K.; Kagi, H.; Yasuzuka, T.; Koizumi, T.; Iizuka, R.; Sugiyama, K.; Yokoyama, Y.

    2011-10-01

    We designed a new cell assembly of diamond anvil cells for single crystal x-ray diffraction under pressure and demonstrate the application of the cell to the crystallographic studies for ice VI and ethanol high-pressure (HP) phase at 0.95(5) GPa and 1.95(2) GPa, respectively. The features of the assembly are: (1) the platy anvil and unique-shaped backing seat (called as "Wing seat") allowing the extremely wide opening angle up to ±65°, (2) the PFA-bulk metallic glass composite gasket allowing the easy attenuation correction and less background. Thanks to the designed assembly, the Rint values after attenuation corrections are fairly good (0.0125 and 0.0460 for ice VI and ethanol HP phase, respectively), and the errors of the refined parameters are satisfactory small even for hydrogen positions, those are comparable to the results which obtained at ambient conditions. The result for ice VI is in excellent agreement with the previous study, and that for ethanol HP phase has remarkable contributions to the revision to its structure; the H12 site, which makes gauche molecules with O1, C2, and C3 sites, may not exist so that only trans conformers are present at least at 1.95(2) GPa. The accurate intensities using the cell assembly allow us to extract the electron density for ethanol HP phase by the maximum entropy method.

  7. Transmission electron microscope observation of the high-pressure form of magnesite retrieved from laser heated diamond anvil cell [rapid communication

    NASA Astrophysics Data System (ADS)

    Irifune, Tetsuo; Isshiki, Maiko; Sakamoto, Shizue

    2005-10-01

    We applied focused ion beam (FIB) technique to make a thin foil for transmission electron microscope (TEM) observations of MgCO 3 magnesite and its new high-pressure form (magnesite II) recovered from laser heated diamond anvil cell (LHDAC), both of which should play fundamental roles in the circulation of carbon in the lower mantle. Heterogeneous microstructures due to significant temperature gradients were observed along the axial direction of the disk sample (˜ 100 μm in diameter and ˜ 30 μm thick), in spite of double-sided laser heating and the use of thermal insulators between the diamond anvil and the sample. The central portion of the MgCO 3 sample was found amorphous, while the peripheral part remained magnesite, on the basis of electron diffraction measurements with TEM. This and our earlier results based on in situ X-ray diffraction measurements suggest that magnesite transformed to magnesite II only at the central part where the temperatures should have been significantly higher than those near the pressure medium. Magnesite II was amorphisized on release of pressure, in contrast to our interpretation that it was converted back to magnesite based solely on in situ X-ray diffraction measurements. The new method of combining the FIB technique with TEM observation thus provides important information on phase transitions under very high pressure using LHDAC, which may be overlooked by in situ optical and X-ray diffraction measurements.

  8. CO Signatures in Subtropical Convective Clouds and Anvils During CRYSTAL-FACE: An Analysis of Convective Transport and Entertainment Using Observations and a Cloud-Resolving Model

    NASA Technical Reports Server (NTRS)

    Lopez, Jimena P.; Fridlind, Ann M.; Jost, Hans-Jurg; Loewenstein, Max; Ackerman, Andrew S.; Campos, Teresa L.; Weinstock, Elliot M.; Sayres, David S.; Smith, Jessica B.; Pittman, Jasna V.; Hallar, A. Gannet; Avallone, Linnea M.; Davis, Sean M.; Herman, Robert L.

    2006-01-01

    Convective systems are an important mechanism in the transport of boundary layer air into the upper troposphere. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers-Florida Area Cirrus Experiment (CRYSTAL-FACE) campaign, in July 2002, was developed as a comprehensive atmospheric mission to improve knowledge of subtropical cirrus systems and their roles in regional and global climate. In situ measurements of carbon monoxide (CO), water vapor (H20v), and total water (H20t) aboard NASA's . WB-57F aircraft and CO aboard the U.S. Navy's Twin Otter aircraft were obtained to study the role of convective transport. Three flights sampled convective outflow on 11, 16 and 29 July found varying degrees of CO enhancement relative to the fiee troposphere. A cloud-resolving model used the in situ observations and meteorological fields to study these three systems. Several methods of filtering the observations were devised here using ice water content, relative humidity with respect to ice, and particle number concentration as a means to statistically sample the model results to represent the flight tracks. A weighted histogram based on ice water content observations was then used to sample the simulations for the three flights. In addition, because the observations occurred in the convective outflow cirrus and not in the storm cores, the model was used to estimate the maximum CO within the convective systems. In general, anvil-level air parcels contained an estimated 20-40% boundary layer air in the analyzed storms.

  9. X-radiography, XRD and Ultrasonic Data Transfer Function Technique - Simultaneous Measurements Under Simulated Mantle Conditions in a Multi-Anvil Device

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Schilling, F. R.; Lathe, C.

    2004-05-01

    The interpretation of seismic data from the Earth's deep interior requires measurements of the physical properties of Earth materials under experimental simulated mantle conditions. Elastic wave velocity measurement is an important tool for the determination of the elastic properties. Ultrasonic interferometry allows the highly precise travel time measurement at a sample enclosed in a high-pressure multi-anvil device. But the calculation of wave velocities requires the exact sample length under in situ conditions. There are two options - scanning the interfaces of the sample by XRD (Mueller et al., 2003) and X-radiography (Li et al., 2001). The multi-anvil apparatus MAX80 is equipped for both methods. Only the X-radiography is fast enough for transient measurements. Contrary to XRD measurements, imaging the sample by X-rays requires a beam diameter larger than the sample length. Therefore the fixed primary slits of Max80 were exchanged by 4-blade high precision slits of Advanced Design Consulting, Inc. A Ce-YAG-crystal converts the X-ray image to an optical one, redirected by a mirror and captured by a CCD-camera. To derive the sample length, the different brightness of sample, buffer rod and reflector at the electronic image is evaluated. Classical ultrasonic interferometry is very time consuming, because the ultrasonic waves of the frequency range under study are generated and detected one after another with a given step rate. A 60 MHz frequency sweep with 100 kHz steps lasts for more than 30 minutes. This is a serious limitation for all transient measurements, but also limits the data collection at elevated temperatures to prevent the pressure transmitting boron epoxy cubes and the anvils from overheating. The ultrasonic transfer function technique (UTF), first described by Li et al. (2002), generates all the frequencies simultaneously. Related to the results and experiences of Li the UTF-technique was developed independently at GFZ. This version allows to

  10. Early African Hominids: Pedagogic Patterns.

    ERIC Educational Resources Information Center

    Newman, James L.

    1984-01-01

    By studying early African hominids, students can learn about the interactive testing and creative aspects of scientific thinking and sharpen their geographical skills. It is impossible to study this topic without giving prominence to space and time. (RM)

  11. The African Pediatric Fellowship Program: Training in Africa for Africans.

    PubMed

    Wilmshurst, Jo M; Morrow, Brenda; du Preez, Avril; Githanga, David; Kennedy, Neil; Zar, Heather J

    2016-01-01

    Africa has a significant burden of childhood disease, with relatively few skilled health care professionals. The African Paediatric Fellowship Programme was developed by the Department of Pediatrics and Child Health at the University of Cape Town to provide relevant training for African child health professionals, by Africans, within Africa. Trainees identified by partner academic institutions spend 6 months to 2 years training in the Department of Pediatrics and allied disciplines. They then return to their home institution to build practice, training, research, and advocacy. From 2008 to 2015, 73 physicians have completed or are completing training in general pediatrics or a pediatric subspecialty. At 1 year posttraining, 98% to 100% are practicing back in their home institution. The impact of the returning fellows is evident from their practice interventions, research collaborations, and positions as stakeholders who can change health care policies. Thirty-three centers in 13 African countries are partners with the program, and the program template is now followed by other partner sites in Africa. Increasing and retaining the skills pool of African child health specialists is building a network of motivated, highly skilled clinicians who are equipped to advance child health in Africa. PMID:26659458

  12. East African Rift

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Places where the earth's crust has formed deep fissures and the plates have begun to move apart develop rift structures in which elongate blocks have subsided relative to the blocks on either side. The East African Rift is a world-famous example of such rifting. It is characterized by 1) topographic deep valleys in the rift zone, 2) sheer escarpments along the faulted walls of the rift zone, 3) a chain of lakes within the rift, most of the lakes highly saline due to evaporation in the hot temperatures characteristic of climates near the equator, 4) voluminous amounts of volcanic rocks that have flowed from faults along the sides of the rift, and 5) volcanic cones where magma flow was most intense. This example in Kenya displays most of these features near Lake Begoria.

    The image was acquired December 18, 2002, covers an area of 40.5 x 32 km, and is located at 0.1 degrees north latitude, 36.1 degrees east longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  13. Techniques for Elastic Properties Measurements of Partial Molten Rocks, Hydrous Minerals and Melts in Gas Pressure Vessels and Multi-Anvil Devices

    NASA Astrophysics Data System (ADS)

    Mueller, H. J.; Roetzler, K.; Schilling, F. R.; Wehber, M.; Lathe, C.

    2008-12-01

    The interpretation of highly resolved seismic data from Earth's deep interior require measurements of the physical properties of Earth materials under experimental simulated mantle conditions. For deep crustal to uppermost mantle conditions high performance gas pressure vessels enable a virtually unrestricted optimization of the measuring configurations for high p-T-conditions [1]. Exhumed high pressure rocks can be used as representative samples. The paper presents transient measurements of elastic wave velocities for granulite facies rocks under partial melting conditions. Despite the compact natural rock samples as a result of long-term experiments exceeding pressures of 1.5 GPa and temperatures of 1,000°C newly-formed garnets, orthopyroxenes and potash feldspars could be found in the samples after the experiments. Discovering the huge water storage capacity of nominally anhydrous minerals (NAMs) under high pressure conditions dramatically changed our image of state and dynamics of Earth's deep interior [2]. The simulation of these in situ conditions require using of diamond anvil cells (DAC) and multi-anvil devices (MAD) as well as mostly synthetical samples. MADs are more limited in pressure, but provide sample volumes 3 to 7 orders of magnitude bigger. They offer small and even adjustable temperature gradients over the whole sample. The bigger samples make anisotropy and structural effects in complex systems accessible for measurements in principle. Using ultrasonic interferometry the measurement of both elastic wave velocities have no limits for opaque and encapsulated samples. Using the 6 to 8 anvils of a MAD as buffers allow the simultaneous recording of acoustic emissions from different directions of space and consequently the localization of the spikes during ongoing phase transitions and dehydration. The recent development of deformation-DIA MADs (D-DIA) make not only deformation measurements under simulated mantle conditions possible, but also the

  14. An African ethic for nursing?

    PubMed

    Haegert, S

    2000-11-01

    This article derives from a doctoral thesis in which a particular discourse was used as a 'paradigm case'. From this discourse an ethic set within a South African culture arose. Using many cultural 'voices' to aid the understanding of this narrative, the ethic shows that one can build on both a 'justice' and a 'care' ethic. With further development based on African culture one can take the ethic of care deeper and reveal 'layers of understanding'. Care, together with compassion, forms the foundation of morality. Nursing ethics has followed particular western moral philosophers. Often nursing ethics has been taught along the lines of Kohlberg's theory of morality, with its emphasis on rules, rights, duties and general obligations. These principles were universalistic, masculine and noncontextual. However, there is a new ethical movement among Thomist philosophers along the lines to be expounded in this article. Nurses such as Benner, Bevis, Dunlop, Fry and Gadow--to name but a few--have welcomed the concept of an 'ethic of care'. Gilligan's work gave a feminist view and situated ethics in the everyday aspects of responsiveness, responsibility, context and concern. Shutte's search for a 'philosophy for Africa' has resulted in finding similarities in Setiloane and in Senghor with those of Thomist philosophers. Using this African philosophy and a research participant's narrative, an African ethic evolves out of the African proverb: 'A person is a person through other persons', or its alternative rendering: 'I am because we are: we are because I am.' This hermeneutic narrative reveals 'the way affect imbues activity with ethical meaning' within the context of a black nursing sister in a rural South African hospital. It expands upon the above proverb and incorporates the South African constitutional idea of 'Ubuntu' (compassion and justice or humanness). PMID:11221391

  15. Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

    SciTech Connect

    Robert A. Houze, Jr.

    2013-11-13

    We examined cloud radar data in monsoon climates, using cloud radars at Darwin in the Australian monsoon, on a ship in the Bay of Bengal in the South Asian monsoon, and at Niamey in the West African monsoon. We followed on with a more in-depth study of the continental MCSs over West Africa. We investigated whether the West African anvil clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the observed anvil clouds to anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model at high resolution using six different ice-phase microphysical schemes. We carried out further simulations with a cloud-resolving model forced by sounding network budgets over the Niamey region and over the northern Australian region. We have devoted some of the effort of this project to examining how well satellite data can determine the global breadth of the anvil cloud measurements obtained at the ARM ground sites. We next considered whether satellite data could be objectively analyzed to so that their large global measurement sets can be systematically related to the ARM measurements. Further differences were detailed between the land and ocean MCS anvil clouds by examining the interior structure of the anvils with the satellite-detected the CloudSat Cloud Profiling Radar (CPR). The satellite survey of anvil clouds in the Indo-Pacific region was continued to determine the role of MCSs in producing the cloud pattern associated with the MJO.

  16. Structure refinement of sub-cubic-mm volume sample at high pressures by pulsed neutron powder diffraction: application to brucite in an opposed anvil cell

    NASA Astrophysics Data System (ADS)

    Okuchi, Takuo; Tomioka, Naotaka; Purevjav, Narangoo; Abe, Jun; Harjo, Stefanus; Gong, Wu

    2014-04-01

    Neutron powder diffraction measurements of 0.9 mm3 of mixture of deuterated brucite and pressure medium were conducted at pressures to 2.8 GPa, using an opposed anvil cell and a medium-resolution diffractometer at Japan Proton Accelerator Research Complex pulsed neutron source. Spurious-free diffraction patterns were successfully obtained and refined to provide all structural parameters including Debye-Waller factors. Tilting of hydroxyl dipoles of brucite toward one of the three nearest-neighbor oxygen anions was confirmed to be substantial at pressure as low as 1.5 GPa. By this application, technical feasibility to analyze such a small sample has been newly established, which would be useful to extend the applications of neutron diffraction at high pressures.

  17. Thermal equation of state of Molybdenum determined from in situ synchrotron X-ray diffraction with laser-heated diamond anvil cells.

    PubMed

    Huang, Xiaoli; Li, Fangfei; Zhou, Qiang; Meng, Yue; Litasov, Konstantin D; Wang, Xin; Liu, Bingbing; Cui, Tian

    2016-01-01

    Here we report that the equation of state (EOS) of Mo is obtained by an integrated technique of laser-heated DAC and synchrotron X-ray diffraction. The cold compression and thermal expansion of Mo have been measured up to 80 GPa at 300 K, and 92 GPa at 3470 K, respectively. The P-V-T data have been treated with both thermodynamic and Mie-Grüneisen-Debye methods for the thermal EOS inversion. The results are self-consistent and in agreement with the static multi-anvil compression data of Litasov et al. (J. Appl. Phys. 113, 093507 (2013)) and the theoretical data of Zeng et al. (J. Phys. Chem. B 114, 298 (2010)). These high pressure and high temperature (HPHT) data with high precision firstly complement and close the gap between the resistive heating and the shock compression experiment. PMID:26883479

  18. New developments in laser-heated diamond anvil cell with in situ synchrotron x-ray diffraction at High Pressure Collaborative Access Team

    SciTech Connect

    Meng, Yue; Hrubiak, Rostislav; Rod, Eric; Shen, Guoyin; Boehler, Reinhard

    2015-07-15

    An overview of the in situ laser heating system at the High Pressure Collaborative Access Team, with emphasis on newly developed capabilities, is presented. Since its establishment at the beamline 16-ID-B a decade ago, laser-heated diamond anvil cell coupled with in situ synchrotron x-ray diffraction has been widely used for studying the structural properties of materials under simultaneous high pressure and high temperature conditions. Recent developments in both continuous-wave and modulated heating techniques have been focusing on resolving technical issues of the most challenging research areas. The new capabilities have demonstrated clear benefits and provide new opportunities in research areas including high-pressure melting, pressure-temperature-volume equations of state, chemical reaction, and time resolved studies.

  19. Thermal equation of state of Molybdenum determined from in situ synchrotron X-ray diffraction with laser-heated diamond anvil cells

    DOE PAGESBeta

    Huang, Xiaoli; Li, Fangfei; Zhou, Qiang; Meng, Yue; Litasov, Konstantin D.; Wang, Xin; Liu, Bingbing; Cui, Tian

    2016-02-17

    Here we report that the equation of state (EOS) of Mo is obtained by an integrated technique of laser-heated DAC and synchrotron X-ray diffraction. The cold compression and thermal expansion of Mo have been measured up to 80 GPa at 300 K, and 92 GPa at 3470 K, respectively. The P-V-T data have been treated with both thermodynamic and Mie–Gruneisen-Debye methods for the thermal EOS inversion. The results are self-consistent and in agreement with the static multi-anvil compression data of Litasov et al. (J. Appl. Phys. 113, 093507 (2013)) and the theoretical data of Zeng et al. (J. Phys. Chem.more » B 114, 298 (2010)). Furthermore, these high pressure and high temperature (HPHT) data with high precision firstly complement and close the gap between the resistive heating and the shock compression experiment.« less

  20. Thermal equation of state of Molybdenum determined from in situ synchrotron X-ray diffraction with laser-heated diamond anvil cells

    NASA Astrophysics Data System (ADS)

    Huang, Xiaoli; Li, Fangfei; Zhou, Qiang; Meng, Yue; Litasov, Konstantin D.; Wang, Xin; Liu, Bingbing; Cui, Tian

    2016-02-01

    Here we report that the equation of state (EOS) of Mo is obtained by an integrated technique of laser-heated DAC and synchrotron X-ray diffraction. The cold compression and thermal expansion of Mo have been measured up to 80 GPa at 300 K, and 92 GPa at 3470 K, respectively. The P-V-T data have been treated with both thermodynamic and Mie-Grüneisen-Debye methods for the thermal EOS inversion. The results are self-consistent and in agreement with the static multi-anvil compression data of Litasov et al. (J. Appl. Phys. 113, 093507 (2013)) and the theoretical data of Zeng et al. (J. Phys. Chem. B 114, 298 (2010)). These high pressure and high temperature (HPHT) data with high precision firstly complement and close the gap between the resistive heating and the shock compression experiment.

  1. Finite element analysis of the effect of electrodes placement on accurate resistivity measurement in a diamond anvil cell with van der Pauw technique

    SciTech Connect

    Wu Baojia; Huang Xiaowei; Han Yonghao; Gao Chunxiao; Peng Gang; Liu Cailong; Wang Yue; Cui Xiaoyan; Zou Guangtian

    2010-05-15

    The van der Pauw technique is widely used to determine resistivity of materials. In diamond anvil cell the compressed sample will make the contact placement change under high pressure. Using finite element analysis, we study the effect of contact placement error induced by pressure on the resistivity measurement accuracy of van der Pauw method. The results show the contact placement has a significant effect on determination accuracy. This method can provide accurate determination of sample resistivity when the spacing b between the contact center and sample periphery is less than D/9 (sample diameter). And the effect of contact placement error on accuracy rapidly increases as the contact location is closing to the sample center. For the same contact placement, the contact size error has a more obvious effect on the semiconductor sample.

  2. Do chimpanzees (Pan troglodytes) use cleavers and anvils to fracture Treculia africana fruits? Preliminary data on a new form of percussive technology.

    PubMed

    Koops, Kathelijne; McGrew, William C; Matsuzawa, Tetsuro

    2010-04-01

    Wild chimpanzees (Pan troglodytes) are renowned for their use of tools in activities ranging from foraging to social interactions. Different populations across Africa vary in their tool use repertoires, giving rise to cultural variation. We report a new type of percussive technology in food processing by chimpanzees in the Nimba Mountains, Guinea: Treculia fracturing. Chimpanzees appear to use stone and wooden "cleavers" as tools, as well as stone outcrop "anvils" as substrate to fracture the large and fibrous fruits of Treculia africana, a rare but prized food source. This newly described form of percussive technology is distinctive, as the apparent aim is not to extract an embedded food item, as is the case in nut cracking, baobab smashing, or pestle pounding, but rather to reduce a large food item to manageably sized pieces. Furthermore, these preliminary data provide the first evidence of chimpanzees using two types of percussive technology for the same purpose. PMID:19967575

  3. Detection of a P-induced liquid ⇌ solid-phase transformation using multiple acoustic transducers in a multi-anvil apparatus

    NASA Astrophysics Data System (ADS)

    Officer, Timothy; Secco, Richard A.

    2015-07-01

    A technique for detecting and measuring phase transitions in a multi-anvil apparatus by measuring the change in travel time for a longitudinal sound wave as a function of pressure is reported. The system measures the time for pulsed ultrasonic signals to travel through a high pressure assembly with a sample in the center. Upon phase change from liquid to solid, the travel time shows an abrupt decrease due to the intrinsic increase in velocity in the sample and a reduced delay between the triggering of an amplitude threshold and the arrival of the waveform. As a proof of concept, results are shown for mercury as it undergoes pressure-induced liquid ⇌ solid transitions at room temperature. We propose that this non-destructive technique may be valuable in situations where other in situ probing techniques cannot be readily used to provide information about changes of state and potentially to study transition kinetics at high pressures as well.

  4. Thermal equation of state of Molybdenum determined from in situ synchrotron X-ray diffraction with laser-heated diamond anvil cells

    PubMed Central

    Huang, Xiaoli; Li, Fangfei; Zhou, Qiang; Meng, Yue; Litasov, Konstantin D.; Wang, Xin; Liu, Bingbing; Cui, Tian

    2016-01-01

    Here we report that the equation of state (EOS) of Mo is obtained by an integrated technique of laser-heated DAC and synchrotron X-ray diffraction. The cold compression and thermal expansion of Mo have been measured up to 80 GPa at 300 K, and 92 GPa at 3470 K, respectively. The P-V-T data have been treated with both thermodynamic and Mie–Grüneisen-Debye methods for the thermal EOS inversion. The results are self-consistent and in agreement with the static multi-anvil compression data of Litasov et al. (J. Appl. Phys. 113, 093507 (2013)) and the theoretical data of Zeng et al. (J. Phys. Chem. B 114, 298 (2010)). These high pressure and high temperature (HPHT) data with high precision firstly complement and close the gap between the resistive heating and the shock compression experiment. PMID:26883479

  5. Melting temperatures of H2O up to 72 GPa measured in a diamond anvil cell using CO2 laser heating technique.

    PubMed

    Kimura, T; Kuwayama, Y; Yagi, T

    2014-02-21

    The melting curve of H2O from 49 to 72 GPa was determined by using a laser-heated diamond anvil cell. Double-sided CO2 laser heating technique was employed in order to heat the sample directly. Discontinuous changes of the heating efficiency attributed to the H2O melting were observed between 49 and 72 GPa. The obtained melting temperatures at 49 and 72 GPa are 1200 and 1410 K, respectively. We found that the slope of the melting curve significantly decreases with increasing pressure, only 5 K/GPa at 72 GPa while 44 K/GPa at 49 GPa. Our results suggest that the melting curve does not intersect with the isentropes of Uranus and Neptune, and hence, H2O should remain in the liquid state even at the pressure and temperature conditions found deep within Uranus and Neptune. PMID:24559351

  6. African American Males. A Critical Link in the African American Family.

    ERIC Educational Resources Information Center

    Jones, Dionne J., Ed.

    African Americans are experiencing extreme stress in the United States, and African-American males appear to suffer the most. The chapters in this volume examine some of the issues confronting African-American men today. They include: (1) "Introduction" (Dionne J. Jones); (2) "Reaffirming Young African American Males: Mentoring and Community…

  7. African American Preschoolers' Language, Emergent Literacy Skills, and Use of African American English: A Complex Relation

    ERIC Educational Resources Information Center

    Connor, Carol McDonald; Craig, Holly K.

    2006-01-01

    Purpose: This study examined the relation between African American preschoolers' use of African American English (AAE) and their language and emergent literacy skills in an effort to better understand the perplexing and persistent difficulties many African American children experience learning to read proficiently. Method: African American…

  8. Technical Consulting: The African-American Perspective

    ERIC Educational Resources Information Center

    Whitfield, Tracy N.

    2010-01-01

    The qualitative research study explored the organizational characteristics necessary in addressing the low concentration of African American technical consultants employed in the information technology industry. Using research participants' professional experience, participants responded to a developed questionnaire. African American technical…

  9. Towards an African Philosophy of Education.

    ERIC Educational Resources Information Center

    Ocaya-Lakidi, Dent

    1980-01-01

    Compares and contrasts contemporary philosophies of education in Africa with two philosophical doctrines (naturalism and idealism). Topics discussed include value selectors, westernization, the role of missionaries in African education, critical consciousness, relevance, and African education today. (DB)

  10. African N Assessment

    NASA Astrophysics Data System (ADS)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  11. Effects of gasket on coupled plastic flow and strain-induced phase transformations under high pressure and large torsion in a rotational diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Feng, Biao; Levitas, Valery I.

    2016-01-01

    Combined plastic flow and strain-induced phase transformations (PTs) under high pressure in a sample within a gasket subjected to three dimensional compression and torsion in a rotational diamond anvil cell (RDAC) are studied using a finite element approach. The results are obtained for the weaker, equal-strength, and stronger high-pressure phases in comparison with low-pressure phases. It is found that, due to the strong gasket, the pressure in the sample is relatively homogenous and the geometry of the transformed zones is mostly determined by heterogeneity in plastic flow. For the equal-strength phases, the PT rate is higher than for the weaker and stronger high-pressure phases. For the weaker high-pressure phase, transformation softening induces material instability and leads to strain and PT localization. For the stronger high-pressure phase, the PT is suppressed by strain hardening during PT. The effect of the kinetic parameter k that scales the PT rate in the strain-controlled kinetic equation is also examined. In comparison with a traditional diamond anvil cell without torsion, the PT progress is much faster in RDAC under the same maximum pressure in the sample. Finally, the gasket size and strength effects are discussed. For a shorter and weaker gasket, faster plastic flow in radial and thickness directions leads to faster PT kinetics in comparison with a longer and stronger gasket. The rates of PT and plastic flows are not very sensitive to the modest change in a gasket thickness. Multiple experimental results are reproduced and interpreted. Obtained results allow one to design the desired pressure-plastic strain loading program in the experiments for searching new phases, reducing PT pressure by plastic shear, extracting kinetic properties from experiments with heterogeneous fields, and controlling homogeneity of all fields and kinetics of PTs.

  12. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    NASA Astrophysics Data System (ADS)

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  13. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team.

    PubMed

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-01

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here. PMID:26233342

  14. The laser micro-machining system for diamond anvil cell experiments and general precision machining applications at the High Pressure Collaborative Access Team

    SciTech Connect

    Hrubiak, Rostislav; Sinogeikin, Stanislav; Rod, Eric; Shen, Guoyin

    2015-07-15

    We have designed and constructed a new system for micro-machining parts and sample assemblies used for diamond anvil cells and general user operations at the High Pressure Collaborative Access Team, sector 16 of the Advanced Photon Source. The new micro-machining system uses a pulsed laser of 400 ps pulse duration, ablating various materials without thermal melting, thus leaving a clean edge. With optics designed for a tight focus, the system can machine holes any size larger than 3 μm in diameter. Unlike a standard electrical discharge machining drill, the new laser system allows micro-machining of non-conductive materials such as: amorphous boron and silicon carbide gaskets, diamond, oxides, and other materials including organic materials such as polyimide films (i.e., Kapton). An important feature of the new system is the use of gas-tight or gas-flow environmental chambers which allow the laser micro-machining to be done in a controlled (e.g., inert gas) atmosphere to prevent oxidation and other chemical reactions in air sensitive materials. The gas-tight workpiece enclosure is also useful for machining materials with known health risks (e.g., beryllium). Specialized control software with a graphical interface enables micro-machining of custom 2D and 3D shapes. The laser-machining system was designed in a Class 1 laser enclosure, i.e., it includes laser safety interlocks and computer controls and allows for routine operation. Though initially designed mainly for machining of the diamond anvil cell gaskets, the laser-machining system has since found many other micro-machining applications, several of which are presented here.

  15. Combined resistive and laser heating technique for in situ radial X-ray diffraction in the diamond anvil cell at high pressure and temperature

    SciTech Connect

    Miyagi, Lowell; Kanitpanyacharoen, Waruntorn; Kaercher, Pamela; Wenk, Hans-Rudolf; Alarcon, Eloisa Zepeda; Raju, Selva Vennila; Knight, Jason; MacDowell, Alastair; Williams, Quentin

    2013-02-15

    To extend the range of high-temperature, high-pressure studies within the diamond anvil cell, a Liermann-type diamond anvil cell with radial diffraction geometry (rDAC) was redesigned and developed for synchrotron X-ray diffraction experiments at beamline 12.2.2 of the Advanced Light Source. The rDAC, equipped with graphite heating arrays, allows simultaneous resistive and laser heating while the material is subjected to high pressure. The goals are both to extend the temperature range of external (resistive) heating and to produce environments with lower temperature gradients in a simultaneously resistive- and laser-heated rDAC. Three different geomaterials were used as pilot samples to calibrate and optimize conditions for combined resistive and laser heating. For example, in Run1, FeO was loaded in a boron-mica gasket and compressed to 11 GPa then gradually resistively heated to 1007 K (1073 K at the diamond side). The laser heating was further applied to FeO to raise temperature to 2273 K. In Run2, Fe-Ni alloy was compressed to 18 GPa and resistively heated to 1785 K (1973 K at the diamond side). The combined resistive and laser heating was successfully performed again on (Mg{sub 0.9}Fe{sub 0.1})O in Run3. In this instance, the sample was loaded in a boron-kapton gasket, compressed to 29 GPa, resistive-heated up to 1007 K (1073 K at the diamond side), and further simultaneously laser-heated to achieve a temperature in excess of 2273 K at the sample position. Diffraction patterns obtained from the experiments were deconvoluted using the Rietveld method and quantified for lattice preferred orientation of each material under extreme conditions and during phase transformation.

  16. Tropical convective systems life cycle characteristics from geostationary satellite and precipitating estimates derived from TRMM and ground weather radar observations for the West African and South American regions

    NASA Astrophysics Data System (ADS)

    Fiolleau, T.; Roca, R.; Angelis, F. C.; Viltard, N.

    2012-12-01

    In the tropics most of the rainfall comes in the form of individual storm events embedded in the synoptic circulations (e.g., monsoons). Understanding the rainfall and its variability hence requires to document these highly contributing tropical convective systems (MCS). Our knowledge of the MCS life cycle, from a physical point of view mainly arises from individual observational campaigns heavily based on ground radar observations. While this large part of observations enabled the creation of conceptual models of MCS life cycle, it nevertheless does not reach any statistically significant integrated perspective yet. To overcome this limitation, a composite technique, that will serve as a Day-1 algorithm for the Megha-Tropiques mission, is considered in this study. this method is based on a collocation in space and time of the level-2 rainfall estimates (BRAIN) derived from the TMI radiometer onboard TRMM with the cloud systems identified by a new MCS tracking algorithm called TOOCAN and based on a 3-dimensional segmentation (image + time) of the geostationary IR imagery. To complete this study, a similar method is also developed collocating the cloud systems with the precipitating features derived from the ground weather radar which has been deployed during the CHUVA campaign over several Brazilian regions from 2010 up to now. A comparison of the MCSs life cycle is then performed for the 2010-2012 summer seasons over the West African, and South American regions. On the whole region of study, the results show that the temporal evolution of the cold cloud shield associated to MCSs describes a symmetry between the growth and the decay phases. It is also shown that the parameters of the conceptual model of MCSs are strongly correlated, reducing thereby the problem to a single degree of freedom. At the system scale, over both land and oceanic regions, rainfall is described by an increase at the beginning (the first third) of the life cycle and then smoothly decreases

  17. The African Cultural Astronomy Project

    NASA Astrophysics Data System (ADS)

    Urama, Johnson O.; Holbrook, Jarita C.

    2011-06-01

    Indigenous, endogenous, traditional, or cultural astronomy focuses on the many ways that people and cultures interact with celestial bodies. In most parts of Africa, there is very little or no awareness about modern astronomy. However, like ancient people everywhere, Africans wondered at the sky and struggled to make sense of it. The African Cultural Astronomy Project aims to unearth the body of traditional knowledge of astronomy possessed by peoples of the different ethnic groups in Africa and to consider scientific interpretations when appropriate for cosmogonies and ancient astronomical practices. Regardless of scientific validity, every scientist can relate to the process of making observations and creating theoretical mechanisms for explaining what is observed. Through linking the traditional and the scientific, it is believed that this would be used to create awareness and interest in astronomy in most parts of Africa. This paper discusses the vision, challenges and prospects of the African Cultural Astronomy Project in her quest to popularize astronomy in Africa.

  18. West African crude production diversifies

    SciTech Connect

    Aalund, L.

    1983-06-01

    Nigeria, with its seven crude-oil export streams, dominated West African production and accounted for over 70% of the depressed 1.8 million b/d output from the region last year. However, during the 1970s a flurry of new producing fields, primarily off the African coast, diversified production among a number of countries and touched off a wave of oil activity. The Journal takes a close look at the quality of West African oil in this installment of assays on world export crudes. This issue covers, in alphabetical order, Bonny Light (Nigeria) to Espoir (Ivory Coast). A following issue will wrap up West Africa by presenting assays on crudes from Forcados Blend (Nigeria) to Zaire Crude (Zaire).

  19. Plio-pleistocene African climate

    SciTech Connect

    deMenocal, P.B.

    1995-10-06

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated. 65 refs., 6 figs.

  20. Plio-Pleistocene African Climate

    NASA Astrophysics Data System (ADS)

    Demenocal, Peter B.

    1995-10-01

    Marine records of African climate variability document a shift toward more arid conditions after 2.8 million years ago (Ma), evidently resulting from remote forcing by cold North Atlantic sea-surface temperatures associated with the onset of Northern Hemisphere glacial cycles. African climate before 2.8 Ma was regulated by low-latitude insolation forcing of monsoonal climate due to Earth orbital precession. Major steps in the evolution of African hominids and other vertebrates are coincident with shifts to more arid, open conditions near 2.8 Ma, 1.7 Ma, and 1.0 Ma, suggesting that some Pliocene (Plio)-Pleistocene speciation events may have been climatically mediated.

  1. The Education of African-Americans.

    ERIC Educational Resources Information Center

    Willie, Charles V., Ed.; And Others

    The 17 papers in this volume are products of a study group on the education of African Americans that was part of a national project, "The Assessment of the Status of African-Americans." The volume takes a comprehensive look at the education of African Americans, specifically early childhood through postsecondary education, and relevant public…

  2. An Introduction to West African Literature.

    ERIC Educational Resources Information Center

    Taiwo, Oladele

    Intended to provide help for those interested in studying West African literature, this book is divided into three parts. Part One provides background information: the various African oral traditions are discussed, related to the way of life of the people, and examined for the extent to which they form the basis of present West African literary…

  3. Engaging African Americans in Smoking Cessation Programs

    ERIC Educational Resources Information Center

    Wallen, Jacqueline; Randolph, Suzanne; Carter-Pokras, Olivia; Feldman, Robert; Kanamori-Nishimura, Mariano

    2014-01-01

    Background: African Americans are disproportionately exposed to and targeted by prosmoking advertisements, particularly menthol cigarette ads. Though African Americans begin smoking later than whites, they are less likely to quit smoking than whites. Purpose: This study was designed to explore African American smoking cessation attitudes,…

  4. Freedom Road: Adult Education of African Americans.

    ERIC Educational Resources Information Center

    Peterson, Elizabeth A., Ed.

    This book contains six chapters by various authors about the history of African Americans' contributions and participation in adult education. The book reports on how some African American leaders saw the connection between education and the eventual freedom or uplift of the African American people. Following a foreword (Phyllis M. Cunningham) and…

  5. A Scale To Assess African American Acculturation.

    ERIC Educational Resources Information Center

    Snowden, Lonnie R.; Hines, Alice M.

    1999-01-01

    Investigated an acculturation scale designed for use in the African-American population. Responses from more than 900 African Americans generally indicate an African-American orientation within the sample, although there are notable variations on all 10 scale items. Discusses evidence for scale reliability and validity. (SLD)

  6. Towards a Norm in South African Englishes.

    ERIC Educational Resources Information Center

    van der Walt, Johann L.; van Rooy, Bertus

    2002-01-01

    Investigates the perception and application of the norm in South African English with specific reference to Black South African English. Hypothesizes that South African English is in the hibernation and expansion phase. Three sets of data are presented and analyzed. (Author/VWL)

  7. African Heritage Curriculum Materials. Teacher's Manual.

    ERIC Educational Resources Information Center

    Museum of African Art, Washington, DC.

    This guide for secondary teachers focuses on sub-Saharan (Black) African history and culture. Although the guide is intended to be used in conjunction with the audiovisual materials on African heritage produced by the Museum of African Art, it can also be used as a source of background reading for teachers and as a guide to additional…

  8. African-American Children's Stories.

    ERIC Educational Resources Information Center

    Nichols, Patricia C.

    Examination of representative stories told by black American children of West African descent in South Carolina shows that specific cultural motifs have been preserved in the oral tradition of black communities. Typical stories are tales of the supernatural, such as the Hag story about mortals who shed their skin at night to do evil deeds.…

  9. African American Men in College

    ERIC Educational Resources Information Center

    Cuyjet, Michael J., Ed.

    2006-01-01

    This book is a much-needed resource that includes examples of real-world programs and activities to enhance academic success in the college environment for African American men. The examples are collected from a variety of institutions across the country. With contributions from leading practitioners and scholars in the field, this book explores…

  10. Vitamin D and African Americans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vitamin D insufficiency is more prevalent among African Americans than other Americans and, in North America, most young, healthy blacks do not achieve optimal 25-hydroxyvitamin D [25(OH)D] concentrations at any time of the year. This is primarily due to the fact that pigmentation reduces vitamin D...

  11. Classic African American Children's Literature

    ERIC Educational Resources Information Center

    McNair, Jonda C.

    2010-01-01

    The purpose of this article is to assert that there are classic African American children's books and to identify a sampling of them. The author presents multiple definitions of the term classic based on the responses of children's literature experts and relevant scholarship. Next, the manner in which data were collected and analyzed in regard to…

  12. Crustal Thickness and Moho Character of the Fast-Spreading East Pacific Rise Between 9º37.5'N and 9º57'N From Poststack and Prestack Time Migrated 3D MCS data

    NASA Astrophysics Data System (ADS)

    Nedimovic, M. R.; Aghaei, O.; Carbotte, S. M.; Carton, H. D.; Canales, J. P.

    2014-12-01

    We measured crustal thickness and mapped Moho transition zone (MTZ) character over an 880 km2 section of the fast-spreading East Pacific Rise (EPR) using the first full 3D multichannel seismic (MCS) dataset collected across a mid-ocean ridge (MOR). The 9°42'-9°57'N area was initially investigated using 3D poststack time migration, which was followed by application of 3D prestack time migration (PSTM) to the whole dataset. This first attempt at applying 3D PSTM to MCS data from a MOR environment resulted in the most detailed reflection images of a spreading center to date. MTZ reflections are for the first time imaged below the ridge axis away from axial discontinuities indicating that Moho is formed at zero age at least at some sections of the MOR system. The average crustal thickness and crustal velocity derived from PSTM are 5920±320 m and 6320±290 m/s, respectively. The average crustal thickness varies little from Pacific to Cocos plate suggesting mostly uniform crustal production in the last ~180 Ka. However, the crust thins by ~400 m from south to north. The MTZ reflections were imaged within ~92% of the study area, with ~66% of the total characterized by impulsive reflections interpreted to originate from a thin MTZ and 26% characterized by diffusive reflections interpreted to originate from a thick MTZ. The MTZ is dominantly diffusive at the southern (9°37.5'-9°40'N) and northern (9°51'-9°57'N) ends of the study area, and it is impulsive in the central region (9°42'-9°51'N). No data were collected between 9°40'N and 9°42'N. More efficient mantle melt extraction is inferred within the central region with greater proportion of the lower crust accreted from the axial magma lens than within the northern and southern sections. This along-axis variation in the crustal accretion style may be caused by interaction between the melt sources for the ridge and the local seamounts, which are present within the northern and southern survey sections. Third

  13. Developing anatomical terms in an African language.

    PubMed

    Madzimbamuto, Farai Daniel

    2012-03-01

    Clinical and technical information imparted in most African languages involves inexact terminology and code switching, so it lacks the explanatory power characterised by the English language. African languages are absent in the tertiary science education environment and forums where African scientists could present scientific material in the medium of African languages. This limits the development of African languages in the scientific domain. There has recently been a trend in several African languages to develop and intellectualise them, especially in the field of medical sciences. The ChiShona language is used to explore the ability of an African language to develop new terminology, to name the vertebral skeleton and describe it scientifically. It uses word compounding to demonstrate terminology development. ChiShona has similarities with several hundred other Bantu languages in East, Central and Southern Africa. Advancing this language can promote similar developments in others, making them more explanatory for the lay public and health professionals. PMID:22380900

  14. The UCAR Africa Initiative: Enabling African Solutions to African Needs

    NASA Astrophysics Data System (ADS)

    Pandya, R.; Bruintjes, R.; Foote, B.; Heck, S.; Hermann, S.; Hoswell, L.; Konate, M.; Kucera, P.; Laing, A.; Lamptey, B.; Moncrieff, M.; Ramamurthy, M.; Roberts, R.; Spangler, T.; Traoré, A.; Yoksas, T.; Warner, T.

    2007-12-01

    The University Corporation for Atmospheric Research (UCAR) Africa Initiative (AI) is a coordinated effort aimed at building sustainable partnerships between UCAR and African institutions in order to pursue research and applications for the benefit of the African people. The initiative is based on four fundamental operating principles, concisely summarized by the overall philosophy of enabling African solutions to African needs. The four principles are: • Collaborate with African institutions • Focus on institutional capacity building and research support • Explore science research themes critical to Africa and important for the world • Leverage the research infrastructure in UCAR to add value These principles are realized in a set of pilot activities, chosen for their high probability of short-term results and ability to set the stage for longer-term collaboration. The three pilot activities are listed below. 1. A modest radar network and data-distribution system in Mali and Burkina Faso, including a data-sharing MOU between the Mail and Burkina Faso Weather Services. 2. A partnership among UCAR, the Ghana Meteorological Agency, and the Ghana university community to develop an operational Weather Research and Forecasting (WRF) model for West Africa. The output is used by researchers and operational forecasters in Africa. Model output is also part of a demonstration project that aims to allow humanitarian agencies to share geo-referenced information in Africa via a web portal. 3. A workshop in Ouagadougou, Burkina Faso from April 2-6, 2007, with the theme Improving Lives by Understanding Weather. The workshop, co-organized with Programme SAAGA and the Commité Permanent Inter-Etats de Lutte Contre la Sécheresse dans le Sahel (CILSS), included over 80 participants from 18 countries, and produced a set of recommendations for continued collaboration. Our presentation will provide an update of these pilot activities and point to future directions. Recognizing

  15. Genome-wide patterns of population structure and admixture in West Africans and African Americans.

    PubMed

    Bryc, Katarzyna; Auton, Adam; Nelson, Matthew R; Oksenberg, Jorge R; Hauser, Stephen L; Williams, Scott; Froment, Alain; Bodo, Jean-Marie; Wambebe, Charles; Tishkoff, Sarah A; Bustamante, Carlos D

    2010-01-12

    Quantifying patterns of population structure in Africans and African Americans illuminates the history of human populations and is critical for undertaking medical genomic studies on a global scale. To obtain a fine-scale genome-wide perspective of ancestry, we analyze Affymetrix GeneChip 500K genotype data from African Americans (n = 365) and individuals with ancestry from West Africa (n = 203 from 12 populations) and Europe (n = 400 from 42 countries). We find that population structure within the West African sample reflects primarily language and secondarily geographical distance, echoing the Bantu expansion. Among African Americans, analysis of genomic admixture by a principal component-based approach indicates that the median proportion of European ancestry is 18.5% (25th-75th percentiles: 11.6-27.7%), with very large variation among individuals. In the African-American sample as a whole, few autosomal regions showed exceptionally high or low mean African ancestry, but the X chromosome showed elevated levels of African ancestry, consistent with a sex-biased pattern of gene flow with an excess of European male and African female ancestry. We also find that genomic profiles of individual African Americans afford personalized ancestry reconstructions differentiating ancient vs. recent European and African ancestry. Finally, patterns of genetic similarity among inferred African segments of African-American genomes and genomes of contemporary African populations included in this study suggest African ancestry is most similar to non-Bantu Niger-Kordofanian-speaking populations, consistent with historical documents of the African Diaspora and trans-Atlantic slave trade. PMID:20080753

  16. Polymer-precursor-derived (am-) SiC/TiC composites for resistive heaters in large volume multi-anvil high pressure/high-temperature apparatus

    NASA Astrophysics Data System (ADS)

    Guan, Li; Schwarz, Marcus; Zhang, Rui; Kroke, Edwin

    2016-04-01

    (Amorphous-)SiC/TiC composites for resistive tubular heaters in HP/HT experiments were obtained via a polymer-precursor process. A slurry consisting of a commercial SiC-precursor polymer (allylhydridopolycarbosilane, AHPCS) and TiC powder as conductive filler was applied to the inner walls of zirconia insulation tubes, using a centrifugation-casting method. Resistive coatings with homogeneous thickness of ∼200 μm were obtained. The heaters were tested in octahedral multi-anvil assemblies at ∼10 GPa with simultaneous recording of heating voltage and current. Up to a maximum temperature of ∼1800°C they showed temperature vs. power characteristics reproducible from batch to batch, with resistance decreasing from 0.08 to 0.02 Ω during heating. Microstructural characterization using SEM/EDX was carried out on the recovered SiC/TiC composite material, as well as on pristine resistive heaters directly after coating and curing to 230°C, and after additional pyrolysis at 900°C in argon. In all cases, a stable composite microstructure of an interpenetrating network of TiC particles with either silicon carbide polymer precursor or an amorphous SiC phase were found. The composites were characterized by XRD and thermogravimetry. Further improvement of coating procedure and materials combination (precursor/filler/insulator substrate) may result in advanced coatings, operational well beyond 2000°C.

  17. Heavy metal (Pb, Zn, Cd, Fe, and Cu) contents of plant foliage near the Anvil Range lead/zinc mine, Faro, Yukon Territory.

    PubMed

    Pugh, Rachel E; Dick, David G; Fredeen, Arthur L

    2002-07-01

    Mining and processing of lead (Pb)/zinc (Zn) ore at the Anvil Range mine occurred near the town of Faro in the Yukon Territory, Canada, for approximately 30 years, beginning in 1968. A study was undertaken to examine whether the mining activities had left a detectable "footprint" on the environment in the way of heavy metal phytoaccumulation. Foliage of three native plant species was sampled: bog blueberry (Vaccinium uliginosum), Labrador tea (Ledum groenlandicum), and willow (Salix sp.), at approximately 0.25, 2.5, 12, 30, and 200 (control) km distant from the mill (ore-processing facility at the mine). Foliage samples were oven-dried, wet- or dry-ashed, and analyzed for metal content using ICP-AES. In addition to Pb and Zn, the primary ore constituents, copper (Cu), iron (Fe), and cadmium (Cd), were also assayed. As expected, foliar Pb and Zn concentrations were elevated in plants at the sites closest to the mill, i.e., 0.25 and 2.5 km from the mine facility. Copper and Fe, both essential nutrients for plants, were also elevated in foliage at the sites closest to the mill, but not to a level that would be of concern. Foliar Cd levels were highest in Salix relative to the other species but were not affected by proximity to the mill. Results suggest that Ledum may be the best indicator of high environmental concentrations of Pb, while Salix may be the best indicator of elevated Zn and Cd. PMID:12297090

  18. A new approach to kinetics study of the anhydrite crystallization at 373 K using a diamond anvil cell with Raman spectroscopy.

    PubMed

    Liu, C J; Zheng, H F

    2013-04-01

    A new approach to the kinetics study of anhydrite (CaSO4) crystallization has been performed in situ using a hydrothermal diamond anvil cell with Raman spectroscopy in the pressure range 896-1322 MPa and a constant temperature of 373 K. Transformed volume fraction X(t) was determined from Raman peak intensity of the sulfate ion in aqueous solution. The transformation-time plots display a sigmoidal shape with time, which indicates that the reaction rate is different at each stage of anhydrite crystallization. At 373 K, the rate constant k increases from 1.14 × 10(-4) s(-1) to 1.86 × 10(-3) s(-1), demonstrating a positive effect of pressure on the overall rate at isothermal condition. We first achieved the molar volume change (ΔVm) equal to -1.82 × 10(-5) m(3)∕mol in the course of anhydrite crystallization through Avrami kinetic theory, showing a process of reduction in volume at high pressure and high temperature. According to the exponent n derived from our experiments, a grain-boundary nucleation and diffusion-controlled growth kinetically dominates the crystallization of anhydrite. PMID:23635213

  19. High Pressure in situ Micro-Raman Spectroscopy of Ge-Sn System Synthesized in a Laser Heated Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Sorb, Y. A.; Subramanian, N.; Ravindran, T. R.; Sahu, P. Ch.

    2011-07-01

    GexSn1-x has been predicted to be a direct band-gap semiconductor, but attempts to synthesize this in bulk form by conventional synthesis methods have not been successful on account of the poor solubility of Sn in Ge. In this work, laser heated diamond anvil cell (LHDAC) technique has been employed to explore formation of bulk GexSn1-x (x = 0.7) at varying pressures and temperatures. At ˜8 GPa, in situ micro-Raman spectroscopy done on several regions of temperature quenched samples laser heated up to ˜2000 K reveals vanishing of the intense Ge TO(Γ) phonon at ˜326 cm-1 and appearance of a softer mode, concurrent with appearance of a new high intensity Raman mode at ˜660 cm-1. These indicate dilation of the Ge-Ge bond by virtue of significant miscibility of βSn at these high P-T conditions and hints at formation of new stiff Ge-Sn bonds.

  20. New Experimental Method for In Situ Determination of Material Textures at Simultaneous High-Pressure and -Temperature by Means of Radial Diffraction in the Diamond Anvil Cell.

    NASA Astrophysics Data System (ADS)

    Liermann, H.; Merkel, S.; Miyagi, L.; Wenk, H.; Shen, G.; Cynn, H.; Evans, W. J.

    2007-12-01

    Radial diffraction in the diamond anvil cell (DAC) has long been used to determine the stress state of materials under non-hydrostatic compression. This technique is also a major tool to investigate textures and infer deformation mechanisms in high pressure minerals. However, most of these experiments have been conducted at ambient temperatures and therefore the results of these measurements may be difficult to extrapolate to the deep Earth. Here, we present a new experimental design that was tested at HPCAT sector 16 BMD of the Advanced Photon Source. This method allows in situ measurement of stresses and textures in the DAC at simultaneously high- pressures and -temperatures. Details of this new technique that uses radial diffraction geometry are discussed, including the uses of amorphous boron gaskets, external heating using graphite heater, and membrane pressure control. Current coverage in pressure and temperature (~30 GPa and 1100 oC). The use of the method will be demonstrated with in situ texture measurements on the high-pressure phases of iron. In the experiment, we were able to observe strong textures in bcc-Fe, track the evolution of the texture with increasing temperature and during the bcc to fcc phase transition. Finally, we observed plastic deformation in the fcc phase between 5 and 15 GPa at 850 oC till the nucleation of hcp-Fe.

  1. Hierarchical Multi-Scale Framework for Materials Modeling: Equation of State Implementation and Application to a Taylor Anvil Impact Test of RDX

    NASA Astrophysics Data System (ADS)

    Barnes, Brian; Spear, Carrie; Leiter, Ken; Becker, Richard; Knap, Jaroslaw; Lisal, Martin; Brennan, John

    2015-06-01

    In order to progress towards a materials-by-design capability, we present work on a challenge in continuum-scale modeling: the direct incorporation of complex physical processes in the constitutive evaluation. In this work, we use an adaptive hierarchical multi-scale (HMS) framework running in parallel on a heterogeneous computational environment to couple a fine-scale, particle-based model computing the equation of state (EOS) to the constitutive response in a finite-element multi-physics simulation. The EOS is obtained from high-fidelity materials simulations performed via dissipative particle dynamics methods. This HMS framework is progress towards an innovation infrastructure that will be of great utility for systems in which essential aspects of the material response are too complex to capture by closed form material models. The design, implementation, and performance of the HMS framework are discussed. Also presented is a proof-of-concept Taylor anvil impact test of non-reacting 1,3,5-trinitroperhydro-1,3,5-triazine (RDX).

  2. MCS Large Cluster Systems Software Toolkit

    Energy Science and Technology Software Center (ESTSC)

    2002-11-01

    This package contains a number of systems utilities for managing a set of computers joined in a "cluster". The utilities assist a team of systems administrators in managing the cluster by automating routine tasks, centralizing information, and monitoring individual computers within the cluster. Included in the toolkit are scripts used to boot a computer from a floppy, a program to turn on and off the power to a system, and a system for using amore » database to organize cluster information.« less

  3. African American Therapists Working with African American Families: An Exploration of the Strengths Perspective in Treatment

    ERIC Educational Resources Information Center

    Bell-Tolliver, Laverne; Burgess, Ruby; Brock, Linda J.

    2009-01-01

    With the exception of Hill's (1971, 1999) work, historically much of the literature on African American families has focused more on pathology than strengths. This study used interviews with 30 African American psychotherapists, self-identified as employing a strengths perspective with African American families, to investigate which strengths they…

  4. Karla Holloway to Lead African and African-American Studies at Duke University.

    ERIC Educational Resources Information Center

    Hawkins, B. Denise

    1996-01-01

    The appointment of Karla F. C. Holloway, an African American woman, as director of the Duke University (North Carolina) African American Studies program is representative of an institutional effort to stabilize the program and to recruit African American scholars to the institution, across disciplines. During Holloway's interim directorship,…

  5. 75 FR 2844 - African Development Foundation, Board of Directors Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-19

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, January 26, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  6. 75 FR 14418 - African Development Foundation, Board of Directors Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, April 13, 2010, 9:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  7. 75 FR 45600 - African Development Foundation, Board of Directors Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-03

    ...; ] AFRICAN DEVELOPMENT FOUNDATION African Development Foundation, Board of Directors Meeting Time: Tuesday, August 17, 2010, 8:30 a.m. to 1 p.m. Place: African Development Foundation, Conference Room, 1400...

  8. Cultural aspects of African American eating patterns.

    PubMed

    Airhihenbuwa, C O; Kumanyika, S; Agurs, T D; Lowe, A; Saunders, D; Morssink, C B

    1996-09-01

    The high mortality from diet-related diseases among African Americans strongly suggests a need to adopt diets lower in total fat, saturated fat and salt and higher in fiber. However, such changes would be contrary to some traditional African American cultural practices. Focus group interviews were used to explore cultural aspects of eating patterns among low- and middle-income African Americans recruited from an urban community in Pennsylvania. In total, 21 males and 32 females, aged 13-65+ years were recruited using a networking technique. Participants identified eating practices commonly attributed to African Americans and felt that these were largely independent of socioeconomic status. They were uncertain about links between African American eating patterns and African origins but clear about influences of slavery and economic disadvantage. The perception that African American food patterns were characteristically adaptive to external conditions, suggest that, for effective dietary change in African American communities, changes in the food availability will need to precede or take place in parallel with changes recommended to individuals. Cultural attitudes about where and with whom food is eaten emerged as being equivalent in importance to attitudes about specific foods. These findings emphasize the importance of continued efforts to identify ways to increase the relevance of cultural context and meanings in dietary counseling so that health and nutrition interventions are anchored in values as perceived, in this case, by African Americans. PMID:9395569

  9. Race, health, and the African Diaspora.

    PubMed

    Spigner, Clarence

    Health inequalities exist throughout the African Diaspora and are viewed in this article as largely color-coded. In developed, developing, and undeveloped nations today, "racial" stratification is consistently reflected in an inability to provide adequate health regardless of national policy or ideology. For instance, African Americans experience less than adequate health care very similar to Blacks in Britain, in spite of each nations differing health systems. Latin America's Africana Negra communities experience poorer health similar to Blacks throughout the Caribbean. The African continent itself is arguably the poorest on earth. A common history of racism correlates with health disparities across the African Diaspora. PMID:18364304

  10. Gentle Africanized bees on an oceanic island

    PubMed Central

    Rivera-Marchand, Bert; Oskay, Devrim; Giray, Tugrul

    2012-01-01

    Oceanic islands have reduced resources and natural enemies and potentially affect life history traits of arriving organisms. Among the most spectacular invasions in the Western hemisphere is that of the Africanized honeybee. We hypothesized that in the oceanic island Puerto Rico, Africanized bees will exhibit differences from the mainland population such as for defensiveness and other linked traits. We evaluated the extent of Africanization through three typical Africanized traits: wing size, defensive behavior, and resistance to Varroa destructor mites. All sampled colonies were Africanized by maternal descent, with over 65% presence of European alleles at the S-3 nuclear locus. In two assays evaluating defense, Puerto Rican bees showed low defensiveness similar to European bees. In morphology and resistance to mites, Africanized bees from Puerto Rico are similar to other Africanized bees. In behavioral assays on mechanisms of resistance to Varroa, we directly observed that Puerto Rican Africanized bees groomed-off and bit the mites as been observed in other studies. In no other location, Africanized bees have reduced defensiveness while retaining typical traits such as wing size and mite resistance. This mosaic of traits that has resulted during the invasion of an oceanic island has implications for behavior, evolution, and agriculture. PMID:23144660

  11. Deep crustal structure of the North-West African margin from combined wide-angle and reflection seismic data (MIRROR seismic survey)

    NASA Astrophysics Data System (ADS)

    Biari, Y.; Klingelhoefer, F.; Sahabi, M.; Aslanian, D.; Schnurle, P.; Berglar, K.; Moulin, M.; Mehdi, K.; Graindorge, D.; Evain, M.; Benabdellouahed, M.; Reichert, C.

    2015-08-01

    The structure of the Moroccan and Nova Scotia conjugate rifted margins is of key importance for understanding the Mesozoic break-up and evolution of the northern central Atlantic Ocean basin. Seven combined multichannel reflection (MCS) and wide-angle seismic (OBS) data profiles were acquired along the Atlantic Moroccan margin between the latitudes of 31.5° and 33° N during the MIRROR seismic survey in 2011, in order to image the transition from continental to oceanic crust, to study the variation in crustal structure, and to characterize the crust under the West African Coast Magnetic Anomaly (WACMA). The data were modeled using a forward modeling approach. The final models image crustal thinning from 36 km thickness below the continent to approximately 8 km in the oceanic domain. A 100 km wide zone characterized by rough basement topography and high seismic velocities up to 7.4 km/s in the lower crust is observed westward of the West African Coast Magnetic Anomaly. No basin underlain by continental crust has been imaged in this region, as has been identified north of our study area. Comparison to the conjugate Nova Scotian margin shows a similar continental crustal thickness and layer geometry, and the existence of exhumed and serpentinized upper mantle material on the Canadian side only. The oceanic crustal thickness is lower on the Canadian margin.

  12. Environmental health and African Americans.

    PubMed Central

    Walker, B

    1991-01-01

    As environmental health has taken on immensely increased significance in the prevention of disease, dysfunction, and premature death, its boundaries have been anything but stable. This instability, along with a multitude of demographic, social, and economic currents, have brought into stark relief the increasing demand for scientists who have the skills and knowledge to perform environmental risk assessment and implement effective risk management policies and services. Despite this demand far too few African Americans want, or are prepared, to pursue careers in sciences. This paper describes efforts to address this problem and suggests why such initiatives may not yield the desired results. PMID:1951793

  13. Environmental sensing by African trypanosomes.

    PubMed

    Roditi, Isabel; Schumann, Gabriela; Naguleswaran, Arunasalam

    2016-08-01

    African trypanosomes, which divide their life cycle between mammals and tsetse flies, are confronted with environments that differ widely in temperature, nutrient availability and host responses to infection. In particular, since trypanosomes cannot predict when they will be transmitted between hosts, it is vital for them to be able to sense and adapt to their milieu. Thanks to technical advances, significant progress has been made in understanding how the parasites perceive external stimuli and react to them. There is also a growing awareness that trypanosomes use a variety of mechanisms to exchange information with each other, thereby enhancing their chances of survival. PMID:27131101

  14. Improving African American Achievement in Geometry Honors

    ERIC Educational Resources Information Center

    Mims, Adrian B.

    2010-01-01

    This case study evaluated the significance of implementing an enrichment mathematics course during the summer to rising African American ninth graders entitled, "Geometry Honors Preview." In the past, 60 to 70 percent of African American students in this school district had withdrawn from Geometry Honors by the second academic quarter. This study…

  15. Heart Truth for African American Women

    MedlinePlus

    THE HEART TRUTH ® FOR AFRICAN AMERICAN WOMEN: AN ACTION PLAN When you hear the term “heart disease,” what’s your first reaction? Like many women, you may ... in four women dies of heart disease. For African American women, the risk of heart disease is especially ...

  16. A Mirror Image African American Student Reflections

    ERIC Educational Resources Information Center

    Cannon Dawson, Candice

    2012-01-01

    This dissertation is a narrative inquiry research project that focuses on the collegiate experiences of African American students at both historically black colleges and universities (HBCUs) and predominantly white institutions (PWIs). I look at how African American college students who engage in race or culturally specific activities, the degree…

  17. The African Student in the American University.

    ERIC Educational Resources Information Center

    Riley, Doris

    This paper gathers information on the values, cognition, and educational background of African students studying at universities in the United States. The section on values notes that Americans are task-oriented individualists, while Africans are primarily relationship-oriented collectivists. These values of sharing and relationship orientation…

  18. African (Black) Psychology: Issues and Synthesis.

    ERIC Educational Resources Information Center

    Baldwin, Joseph A.

    1986-01-01

    Reviews the recent attempts of Black psychologists and social scientists to formulate a conceptual-operational framework for the study of psychological phenomena as they bear on the cultural-survival conditions of Black-African people. Outlines issues and problems in the attempt to define African (Black) psychology and discusses its relation to…

  19. African American Women in Higher Education

    ERIC Educational Resources Information Center

    Zamani, Eboni M.

    2003-01-01

    African American women hold a unique position as members of two groups that have been treated in a peripheral manner by postsecondary education (Moses, 1989). Membership in both marginalized groups often makes African American women invisible in colleges and universities. Given the complex intersection of race and gender, more attention should be…

  20. African-American Student Achievement Research Project.

    ERIC Educational Resources Information Center

    Wagstaff, Mark; Melton, Jerry; Lawless, Brenda; Combs, Linda

    Data from the Texas Assessment of Academic Skills (TAAS) reveal that gains in performance for the African American student population of Region VII of the state's educational system were not keeping pace with the performance of African Americans in the rest of Texas. This study investigated practices in school districts in the region in which…

  1. Cancer and the African American Experience

    Cancer.gov

    The first plenary of the EPEC-O (Education in Palliative and End-of-Life Care for Oncology) Self-Study: Cultural Considerations When Caring for African Americans explores the many factors that lead to inequalities in cancer care outcomes for African Americans.

  2. Computer Networks and African Studies Centers.

    ERIC Educational Resources Information Center

    Kuntz, Patricia S.

    The use of electronic communication in the 12 Title VI African Studies Centers is discussed, and the networks available for their use are reviewed. It is argued that the African Studies Centers should be on the cutting edge of contemporary electronic communication and that computer networks should be a fundamental aspect of their programs. An…

  3. Reading Comprehension among African American Graduate Students

    ERIC Educational Resources Information Center

    Onwuegbuzie, Anthony J.; Mayes, Eric; Arthur, Leslie; Johnson, Joseph; Robinson, Veronica; Ashe, Shante; Elbedour, Salman; Collins, Kathleen M. T.

    2004-01-01

    A study was conducted to examine the reading comprehension performance of African American graduate students. The result showed that though the African American sample attained statistically significantly higher levels of reading comprehension than a normative sample of undergraduate students, they achieved lower levels of reading comprehension…

  4. Technology Builds Global Acceptance among African Students.

    ERIC Educational Resources Information Center

    John, Martha Tyler; John, Floyd Idwal

    This paper describes how a new university, African Nazarene University (ANU) in Kenya, used various means, including computer technology, for implementing learning goals for students from a wide variety of African countries and tribes. The paper stresses that the school, which opened in 1994 with 65 students, emphasized tolerance of differences…

  5. Genetics Home Reference: African iron overload

    MedlinePlus

    ... of a genetic condition? Genetic and Rare Diseases Information Center Frequency African iron overload is common in rural areas of central and ... more about the gene associated with African iron overload SLC40A1 Related Information What is a gene? What is a gene ...

  6. African Higher Education: An International Reference Handbook.

    ERIC Educational Resources Information Center

    Teferra, Damtew, Ed.; Altbach, Philip G., Ed.

    This book is a comprehensive survey of all aspects and dimensions of higher education in Africa. It includes a historical overview of higher education, descriptions of the higher education systems in each African country, and analyses of current and timely topics in higher education. Part 1, "Themes," contains 13 essays on trends in African higher…

  7. African American Art: A Los Angeles Legacy.

    ERIC Educational Resources Information Center

    Walker, Harriet

    This curriculum unit focuses on the importance of Los Angeles (California) as a center for African American art and shows how African American artists have developed their own styles and how critics and collectors have encouraged them. The unit consists of four lessons, each of which can stand alone or be used in conjunction with the others. It…

  8. New data on African health professionals abroad

    PubMed Central

    Clemens, Michael A; Pettersson, Gunilla

    2008-01-01

    Background The migration of doctors and nurses from Africa to developed countries has raised fears of an African medical brain drain. But empirical research on the causes and effects of the phenomenon has been hampered by a lack of systematic data on the extent of African health workers' international movements. Methods We use destination-country census data to estimate the number of African-born doctors and professional nurses working abroad in a developed country circa 2000, and compare this to the stocks of these workers in each country of origin. Results Approximately 65,000 African-born physicians and 70,000 African-born professional nurses were working overseas in a developed country in the year 2000. This represents about one fifth of African-born physicians in the world, and about one tenth of African-born professional nurses. The fraction of health professionals abroad varies enormously across African countries, from 1% to over 70% according to the occupation and country. Conclusion These numbers are the first standardized, systematic, occupation-specific measure of skilled professionals working in developed countries and born in a large number of developing countries. PMID:18186916

  9. Beyond Afrocentricism: Alternatives for African American Studies.

    ERIC Educational Resources Information Center

    Hall, Perry A.

    1991-01-01

    Discusses new directions for African-American studies curricula. Argues that the Afrocentrist perspective presents a static model that does not adequately address the dynamic interaction of Afrocentric sensibility with Western-dominated economic, cultural, and political structures. The African-American studies discipline should be conceptualized…

  10. Traditional African Religion: A Resource Unit.

    ERIC Educational Resources Information Center

    Garland, William E.

    This resource unit is based on research conducted by Lynn Mitchell and Ernest Valenzuela, experienced classroom teachers of African history and culture. The unit consists of an introduction by Mr. Garland and two major parts. Part I is an annotated bibliography of selected sources on various aspects of traditional African Religion useful in…

  11. The African American Woman. Runta (Truth).

    ERIC Educational Resources Information Center

    Jackson, Monica L.; Watson, Betty Collier, Ed.

    1989-01-01

    The African American woman has commanded widespread public attention, but popular misconceptions of her socioeconomic role and status differ sharply from her actual situation. The following basic characteristics of the contemporary African American woman, drawn from census figures, are outlined: (1) demographically, females comprise a majority of…

  12. Kunta Kinte's Struggle to be African

    ERIC Educational Resources Information Center

    Courlander, Harold

    1986-01-01

    This article reveals the differences between the character Kunta Kinte and the historical record concerning African males in the preslavery period. Kunta's non-African behaviors include displays of blind anger and rage, prudishness, and actions unknown in his Mandinka culture. These represent the many misrepresentations and ambiguities in Alex…

  13. France: Africans and the French Revolution.

    ERIC Educational Resources Information Center

    Fatunde, Tunde

    1989-01-01

    The French Revolution had profound and long-term effects for Africans, both in Africa and throughout the Western hemisphere. Revolutionary leaders not only opposed the emancipation of slaves in French territories but supported an intensified slave trade, sparking numerous rebellions. French exploitation of Africans extended well into the twentieth…

  14. African American Undergraduates and the Academic Library

    ERIC Educational Resources Information Center

    Whitmire, Ethelene

    2006-01-01

    This study examines the academic library experiences of African American undergraduates attending a research university in the Midwest. Data collection techniques included questionnaires and ethnographic observations. The results indicated that African American undergraduates are using the academic library primarily to read and to study with their…

  15. Hidden Education among African Americans during Slavery

    ERIC Educational Resources Information Center

    Gundaker, Grey

    2007-01-01

    Background/Context: Historical studies examine aspects of African American education in and out of school in detail (Woodson 1915, 1933, Bullock 1970, Anderson 1988, Morris 1982, Rachal 1986, Rose 1964, Webber 1978, Williams 2005). Scholars of African American literacy have noted ways that education intersects other arenas such as religion and…

  16. British African Caribbean Women and Depression

    ERIC Educational Resources Information Center

    Adkison-Bradley, Carla; Maynard, Donna; Johnson, Phillip; Carter, Stephaney

    2009-01-01

    Depression is a common condition among women in the United Kingdom. However, little is known about the context of depression among British African Caribbean women. This article offers a preliminary discussion regarding issues and information pertaining to depression among British African Caribbean women. Characteristics and symptoms of depression…

  17. Depression, Sociocultural Factors, and African American Women

    ERIC Educational Resources Information Center

    Hunn, Vanessa Lynn; Craig, Carlton David

    2009-01-01

    The authors discuss depression in African American women from a sociocultural perspective, including aspects of oppression and racism that affect symptom manifestation. The authors highlight John Henryism as a coping mechanism, the history and continuing role of the African American church as a safe haven, and strategies for culturally competent…

  18. Phase transitions of CaCO3 at high P and T determined by in-situ Vibrational Spectroscopy in Diamond-Anvil-Cells

    NASA Astrophysics Data System (ADS)

    Koch-Müller, Monika; Jahn, Sandro; Birkholz, Natalie; Schade, Ulrich

    2014-05-01

    Carbonates are the most abundant carbon-bearing minerals on Earth. They can be transported into the upper and lower mantle via subduction processes. Knowledge of the stability of solid carbonates adapting different structures with increasing pressure and temperature is therefore of great importance to understand the structure and dynamics of the Earth. Even for the very simple system CaCO3 the phase relations of at high pressure and temperature are still not fully understood. It has been known for many years that calcite (cc) can adopt different structures with increasing pressure (e.g. Bridgman, 1939: cc-I to III; Tyburczy and Ahrens, 1986: cc-VI). But only recently Merlini et al. (2012) were able to solve the crystal structures of some of these high-pressure polymorphs namely cc-III, cc-IIIb and cc-VI. They report that cc-VI has a higher density then aragonite under the same conditions. To study the stability of the CaCO3-polymorphs, experiments were performed in conventional diamond anvil cells (DAC) at ambient temperatures as a function of pressure up to 30 GPa as well as in internally heated diamond anvil cells (DAC-HT) in the pressure range 9 to 20 GPa and temperatures up to 800 K. As probe for the structural changes we used conventional mid-infrared-, synchrotron far-infrared- and Raman-spectroscopy. Within the cc-III stability field (3 to 15 GPa at room temperature, e.g. Catalli and Williams, 2005) we observed in all types of experiments consistently two different spectral patterns: one at lower P < 5 GPa and another at P > 5 < 15 GPa independent on the starting material and the pressure- and time-path of the experiments. Whether these P-induced structural changes may be linked to the above mentioned different structures of cc-III is not yet clear. Also, in all types of experiments we confirmed the transition of cc-III to cc-VI at about 15 GPa at room temperature. Merlini et al. (2012) speculated that temperature may stabilize the structures of cc-III to

  19. COMPRES X-ray beamlines (X17B3 and X17C) for the diamond anvil cell at the National Synchrotron Light Source

    NASA Astrophysics Data System (ADS)

    Hong, X.; Chen, Z.; Sengupta, A.; Goncharov, A. F.; Ehm, L.; Duffy, T. S.; Weidner, D. J.

    2011-12-01

    The laser heated diamond anvil cell technique can readily achieve the pressure and temperature domain of Earth from upper mantle to outer core. The laser heating diamond anvil cell X-ray facilities (X17-DAC), consists of X17B3 and X17C stations on a superconducting wiggler beamline and a sample preparation/spectroscopy laboratory at the National Synchrotron Light Source). As the first dedicated high-pressure (HP) beamline in the world, X17-DAC has been a workhorse for HP research for two decades, and has led the way in many developments, Here we report current capabilities and recent developments at X17-DAC beamlines including a new double-side laser heating system . At the X17B3 station, high-temperature high-pressure X-ray diffraction experiments can be carried out either with monochromatic beam (~30 keV or ~80 keV), or with white beam for energy dispersive x-ray diffraction. In-situ laser heating system will be available for users in Geosciences starting from September, 2011. With a monochromatic beam at 30 keV, the X-ray beam can be focused to a beam size of ~10 μm. By combing with the laser heating technique, we can support in-situ X-ray diffraction experiments at the domain of temperature and pressure up to Earth's outer core. With high energy at 80 keV, total scattering pair distribution function (PDF) measurements are performed. Originally, this method was used to study amorphous and highly disordered materials, but more recently, it has been used for the analysis of crystalline and nanostructured materials. This novel technique provides useful information about the long- and short-range ordering of the atoms in the materials. It is promising to combine laser heating and total scattering PDF measurements so as to probe phase transitions and phase relations for geophysical important materials at X17B3 station. At X17C, we conduct angle and energy dispersive x-ray diffraction on polycrystalline samples in either axial or radial geometry. Energy dispersive

  20. Deep Recycling of Sedimentary Lithologies in Subduction Zones: Geochemical and Physical Constraints from Phase Equilibria and Synchrotron-Based Multi-Anvil Experiments at 15-25 GPa

    NASA Astrophysics Data System (ADS)

    Rapp, R. P.; Nishiyama, N.; Irifune, T.; Inoue, T.; Yamasaki, D.

    2003-12-01

    Ocean island basalts (OIBs) provide geochemical evidence for the presence of crustally-derived sedimentary material in the deep mantle plume source region for EM-type OIBs, and global seismic tomography provides us with dramatic images of subducted slabs, presumably carrying a sediment component, penetrating through the transition zone and into the lower mantle, in some cases to the core-mantle boundary. In an effort to better constrain the geochemical effects of deeply recycled sedimentary material in subduction zones, and their role in the petrogenesis of EM-type OIBs, we have undertaken a series of phase equlibria experiments in the multi-anvil apparatus at 10-25 GPa, using natural sediment lithologies as starting materials. The goal of these experiments is to identify the dominant phases in deeply subducted sediments, constrain their P-T stability limits, and to assess their role in crustal recycling and element redistribution in the deep mantle during subduction. The phase equilibria experiments were performed in a 2000-ton Kawai-type apparatus, using tungsten carbide cubes with 3 mm TEL and Cr-doped MgO and zirconia pressure media. A cylindrical lanthanum chromite heater was used, along with short (< 1 mm), thick-walled, pressure-welded gold capsules to minimize thermal gradients and to retain the small amounts of water (< 1 wt%) present in the starting material, and long run-durations (12-48 hours) in order to facilitate future analyses of the dominant phases for key trace elements using the ion microprobe. Our preliminary results at 10-25 GPa indicate that K-hollandite (KalSi3O3) and stishovite are the primary high-pressure phases in the sediment composition, with subordinate garnet and an as-yet-unidentified (possibly hydrous) Al-silicate phase present as well. These results suggest that K-hollandite is the primary repository for incompatible elements (e.g., La, Ce, Sr, Ba, Rb, etc., and the heat-producing elements K, U and Th) in sedimentary material