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Sample records for extrusive coherent kimberlite

  1. The Igwisi Hills extrusive 'kimberlites'

    Science.gov (United States)

    Reid, A. M.; Donaldson, C. H.; Dawson, J. B.; Brown, R. W.; Ridley, W. I.

    1975-01-01

    The petrography and mineral chemistry of volcanic rocks from the Igwisi Hills in Tanzania are discussed. There is considerable evidence to suggest that the Igwisi rocks are extrusive kimberlites: a two-component nature with high P-T minerals in a low P-T matrix; the presence of chrome pyrope, Al enstatite, chrome diopside, chromite and olivine; a highly oxidized, volatile-rich matrix with serpentine, calcite, magnetite, perovskite; high Sr, Zr, and Nb contents; occurrence in a narrow isolated vent within a stable shield area. The Igwisi rocks differ from kimberlite in the lack of magnesian ilmenite, the scarcity of matrix phlogopite, and the overall low alkali content. They apparently contain material from phlogopite-bearing garnet peridotites with a primary mineral assemblage indicative of equilibrium at upper mantle temperatures and pressures. This primary assemblage was brought rapidly to the surface in a gas-charged, carbonate-rich fluid. Rapid upward transport, extrusion, and rapid cooling have tended to prevent reaction between inclusions and the carbonate-rich matrix that might otherwise have yielded a more typical kimberlite.

  2. Welded Kimberlite?

    Science.gov (United States)

    van Straaten, B. I.; Kopylova, M. G.; Russell, J. K.; Scott Smith, B. H.

    2009-05-01

    settings. In this contribution we explore the possible welded origin for dark and competent kimberlite facies from the Victor Northwest pipe (Northern Ontario, Canada). This volumetrically extensive facies superficially resembles a coherent rock. The following observations on the dark and competent facies are suggestive of a pyroclastic, rather than intrusive or extrusive coherent origin: The facies is completely enveloped by pyroclastic facies; has gradational contacts with adjacent pyroclastic facies above and below; contains faint outlines of primary pyroclasts; shows diffuse grain size variations and rare bedding; shows systematic changes in components from the underlying pyroclastic facies to the dark and competent facies to the overlying pyroclastic facies implying a lack of a depositional break in this succession; and shows a faint, generally subhorizontal fabric despite the presence of an equant grain shape population. In addition, we present evidence that the original inter-clast porosity has been reduced or eliminated by syn-depositional welding rather than by precipitation of secondary minerals in the inter-clast pore spaces. We feel that the latter process (i.e., alteration) is highly unlikely because: The kimberlite package contains intervals with well crystallized groundmass similar to coherent kimberlite, this texture simply cannot be produced by alteration; the kimberlite is in fact the freshest rock within the pipe, containing mostly fresh olivines; and the dark and competent kimberlite does not show a patchy or vein-related heterogeneity typical of alteration. In summary, these deposits likely represent a variably welded succession of proximal spatter/fire fountaining kimberlite deposits.

  3. Kimberlite Ascent: Insights from Olivine

    Science.gov (United States)

    Brett, C.; Russell, K.

    2009-05-01

    Olivine is ubiquitous in both extrusive and intrusive kimberlite deposits worldwide. Within kimberlite, it is mainly present as xenocrysts derived from the disaggregation of mantle-derived peridotitic xenoliths. Many textural and chemical features within the mantle-derived olivine xenocrysts result from post entrainment processes. On that basis, these features record physical and chemical changes attending kimberlite ascent and can be used to elucidate the transport and eruption of kimberlite magma. Our textural study of kimberlitic olivine is based on intrusive and pyroclastic kimberlite from the Diavik kimberlite cluster and from the Igwisi Hills kimberlitic lava flows. Based on these observations and the physical and chemical properties of olivine we derive a relative sequence of textural events. Textural features include: sealed cracks, healed cracks, phases trapping in cracks, rounded grains, overgrowths and phase trapping in overgrowths. These features record processes that operate in kimberlite during ascent, and from these features we create a summary model for kimberlite ascent: -- Olivine is incorporated into kimberlitic melts in peridotitic mantle xenoliths continuously during ascent. Xenolith incorporation is focused at the crack tip where the stress regime is highest. -- Shortly after the incorporation of these xenocrysts the tensile strength of the xenoliths is reached at a maximum of 2 km from its source. Disaggregation of mantle xenoliths (producing xenocrysts) is facilitated by expansion of the minerals within the xenoliths causing intra-crystal slip (i.e. along grain boundaries). -- Continued decompression causes olivine to also break in tension approximately 20 km from source. The void space produced by the failure of the crystals (inter-crystal cracks) is filled with melt and crystals consisting of primary carbonate (high-Sr), chromite and spinel crystals. The carbonate later crystallizes to produce sealed fractures. -- Mechanical rounding of

  4. Sub-volcanic development of kimberlite pipes: Evidence from the Lace and Voorspoed (Group II) kimberlites, South Africa

    Science.gov (United States)

    Howarth, Geoffrey H.; Skinner, E. Michael W.

    2013-12-01

    The Lace and Voorspoed kimberlites occur on the Kaapvaal Craton (South Africa), and form part of the Kroonstad Group II kimberlite (orangeite) cluster. The Lace kimberlite is composed of a main pipe and a satellite blind pipe, the latter of which does not reach the current land surface (~ 30 m below the current land surface), and is not observed connecting with the main pipe at depth. The main pipe increases in size from ~ 100 m to ~ 250 m in diameter at depth. The Voorspoed kimberlite pipe is the largest of the cluster and is dominantly infilled with massive layers (up to 200 m thick) of resedimented volcaniclastic kimberlite (RVK). Coherent kimberlite (CK), identified at all three pipes, is described here in order to constrain their formation.

  5. Reactive transport and the genesis of kimberlites

    DEFF Research Database (Denmark)

    Pilbeam, Llewellyn; Nielsen, Troels; Waight, Tod Earle

    the southern West Greenland kimberlites sensu lato using similar processes. We may also account for the intercraton variety in kimberlite composition and mineralogy. Mg# and Ni composition was obtained for transects across olivine grains. Pure Rayleigh fractionation did not explain the shape of the nickel...... containing Enstatite, Forsterite and CO2. The ‘parental’ melt for Majuagaa kimberlite was magnesiocarbonatite which entrained 50wt% harzburgite, consistent with melting experiments. The melt processed ~20wt% SiO2 but at any given time had no more than ~5wt% SiO2. We explain geochemical variations across...

  6. Reactive transport and the genesis of kimberlites

    DEFF Research Database (Denmark)

    Pilbeam, Llewellyn; Nielsen, Troels; Waight, Tod Earle

    When studying the bulk rock analysis of kimberlites a significant correction for visible xenocrysts must be made [1,2]. Such studies concluded that olivine in kimberlite has a xenocrystic core and cognate margin. Previously, material entrained by the melt and dissolved during transport has only...... transects. Diffusion between homogeneous olivine grains and melt was also eliminated. The data was replicated using a combination of growth and minor later diffusion. Growth was modeled using AFC equations [4]. Later diffusive equilibration between core and margin was minor. Since kimberlite transport time...

  7. GRAPHITE EXTRUSIONS

    Science.gov (United States)

    Benziger, T.M.

    1959-01-20

    A new lubricant for graphite extrusion is described. In the past, graphite extrusion mixtures have bcen composed of coke or carbon black, together with a carbonaceous binder such as coal tar pitch, and a lubricant such as petrolatum or a colloidal suspension of graphite in glycerin or oil. Sinee sueh a lubricant is not soluble in, or compatible with the biiider liquid, such mixtures were difficult to extrude, and thc formed pieees lacked strength. This patent teaches tbe use of fatty acids as graphite extrusion lubricants and definite improvemcnts are realized thereby since the fatty acids are soluble in the binder liquid.

  8. Geological and Petrographic Characteristics of Kimberlite Pipes

    Directory of Open Access Journals (Sweden)

    N. N. Zinchuk

    2016-12-01

    Full Text Available Studies of the geological structure and petrochemical composition of the Siberian Platform kimberlites indicated complexity, diversity of geological, tectonic, and paleogeographic situations, which must be considered for proper prospecting-exploration for diamonds in each area of investigation. Information about petrochemical composition of potential diatremes, hosting, and overlying sedimentary and magmatic formations is an important prerequisite for prospecting of kimberlite deposits in different geologic-tectonic conditions. The most attention should be paid to typomorphic specific features of primary and secondary minerals of diatremes. Each diamondiferous region is characterized by a certain set of typomorphic associations of kimberlites primary and secondary minerals. The diamonds with ultrabasic association of solid phase inclusions (olivine, chrome-spinel, pyrope, etc. dominate in majority of kimberlite pipes.

  9. The timing of kimberlite magmatism in North America: implications for global kimberlite genesis and diamond exploration

    Science.gov (United States)

    Heaman, L. M.; Kjarsgaard, B. A.; Creaser, R. A.

    2003-12-01

    Based on a compilation of more than 100 kimberlite age determinations, four broad kimberlite emplacement patterns can be recognized in North America: (1) a northeast Eocambrian/Cambrian Labrador Sea province (Labrador, Québec), (2) an eastern Jurassic province (Ontario, Québec, New York, Pennsylvania), (3) a Cretaceous central corridor (Nunavut, Saskatchewan, central USA), and (4) a western mixed (Cambrian-Eocene) Type 3 kimberlite province (Alberta, Nunavut, Northwest Territories, Colorado/Wyoming). Ten new U-Pb perovskite/mantle zircon and Rb-Sr phlogopite age determinations are reported here for kimberlites from the Slave and Wyoming cratons of western North America. Within the Type 3 Slave craton, at least four kimberlite age domains exist: I-a southwestern Siluro-Ordovician domain (˜450 Ma), II-a SE Cambrian domain (˜540 Ma), III-a central Tertiary/Cretaceous domain (48-74 Ma) and IV-a northern mixed domain consisting of Jurassic and Permian kimberlite fields. New U-Pb perovskite results for the 614.5±2.1 Ma Chicken Park and 408.4±2.6 Ma Iron Mountain kimberlites in the State Line field in Colorado and Wyoming confirm the existence of at least two periods of pre-Mesozoic kimberlite magmatism in the Wyoming craton. A compilation of robust kimberlite emplacement ages from North America, southern Africa and Russia indicates that a high proportion of known kimberlites are Cenozoic/Mesozoic. We conclude that a majority of these kimberlites were generated during enhanced mantle plume activity associated with the rifting and eventual breakup of the supercontinent Gondwanaland. Within this prolific period of kimberlite activity, there is a good correlation between North America and Yakutia for three distinct short-duration (˜10 my) periods of kimberlite magmatism at 48-60, 95-105 and 150-160 Ma. In contrast, Cenozoic/Mesozoic kimberlite magmatism in southern Africa is dominated by a continuum of activity between 70-95 and 105-120 Ma with additional less

  10. Food extrusion.

    Science.gov (United States)

    Harper, J M

    1978-01-01

    Extrusion processing has become an important food process in the manufacture of pasta, ready-to-eat cereals, snacks, pet foods, and textured vegetable protein (TVP). An extruder consists of tightly fitting screw rotating within a stationary barrel. Preground and conditioned ingredients enter the screw where they are conveyed, mixed, and heated by a variety of processes. The product exits the extruder through a die where it usually puffs and changes texture from the release of steam and normal forces. Mathematical models for extruder flow and torque have been found useful in describing exclusion operations. Scale-up can be facilitated by the application of these models. A variety of food extruder designs have developed. The differences and similarity of design are discussed. Pertinent literature on the extrusion of cereal/snack products, full-fat soy, TVP, pet foods (dry and semi-moist), pasta, and beverage or other food bases are discussed. In many of these applications, the extruder is a high temperature, short time process which minimizes losses in vitamins and amino acids. Color, flavor, and product shape and texture are also affected by the extrusion process. Extrusion has been widely applied in the production of nutritious foods. Emphasis is placed on the use of extrusion to denature antinutritional factors and the improvement of protein quality and digestibility.

  11. Kimberlite emplacement temperatures from conodont geothermometry

    Science.gov (United States)

    Pell, Jennifer; Russell, James K.; Zhang, Shunxin

    2015-02-01

    Kimberlites are mantle-derived ultramafic rocks preserved in volcanic and sub-volcanic edifices and are the main primary source of diamonds. The temperatures of formation, transport, eruption and deposition remain poorly constrained despite their importance for understanding the petrological and thermodynamic properties of kimberlite magmas and styles of volcanic eruption. Here, we present measured values of Colour Alteration Indices (CAI) for conodonts recovered from 76 Paleozoic carbonate xenoliths found within 11 pipes from the Chidliak kimberlite field on Baffin Island, Nunavut, Canada. The dataset comprises the largest range of CAI values (1.5 to 8) and the highest CAI values reported to date for kimberlite-hosted xenoliths. Thermal models for cooling of the Chidliak kimberlite pipes and synchronous heating of conodont-bearing xenoliths indicate time windows of 10-20 000 h and, for these short time windows, the measured CAI values indicate heating of the xenoliths to temperatures of 225 to >925 °C. We equate these temperatures with the minimum temperatures of the conduit-filling kimberlite deposit (i.e. emplacement temperature, TE). The majority of the xenoliths record CAI values of between 5 and 6.5 suggesting heating of xenoliths to temperatures of 460 °C-735 °C. The highest CAI values are consistent with being heated to 700 °C-925 °C and establish the minimum conditions for welding or formation of clastogenic kimberlite deposits. Lastly, we use TE variations within and between individual pipes, in conjunction with the geology of the conduit-filling deposits, to constrain the styles of explosive volcanic eruption.

  12. Emplacement Temperatures of Pyroclastic and Volcaniclastic Deposits in Kimberlite Pipes in Southern Africa: New constraints From Palaeomagnetic Measurements

    Science.gov (United States)

    Fontana, G. P.; Macniocaill, C.; Brown, R. J.; Sparks, S. R.; Field, M.; Gernon, T. M.

    2009-05-01

    -driven eruptions, and suggest phreatomagmatism did not play a major role in the generation of the deposits. The study indicates that palaeomagnetic methods can successfully distinguish differences in the emplacement temperatures of different kimberlite facies. It also indicates that the post-eruption infill of the pipe may be disrupted by the volcanic activity of nearby kimberlite pipes. Studies are in progress to determine the emplacement temperature of other vent-fill lithofacies, such as dense, coherent pyroclastic kimberlite that may represent high-grade welded deposits. The thermal effects of the pipes on adjacent country rock will be investigated and the results used to further constrain the eruption dynamics and emplacement mechanisms of the studied pipes.

  13. Hydrothermal alteration of kimberlite by convective flows of external water.

    Science.gov (United States)

    Afanasyev, A A; Melnik, O; Porritt, L; Schumacher, J C; Sparks, R S J

    Kimberlite volcanism involves the emplacement of olivine-rich volcaniclastic deposits into volcanic vents or pipes. Kimberlite deposits are typically pervasively serpentinised as a result of the reaction of olivine and water within a temperature range of 130-400 °C or less. We present a model for the influx of ground water into hot kimberlite deposits coupled with progressive cooling and serpentisation. Large-pressure gradients cause influx and heating of water within the pipe with horizontal convergent flow in the host rock and along pipe margins, and upward flow within the pipe centre. Complete serpentisation is predicted for wide ranges of permeability of the host rocks and kimberlite deposits. For typical pipe dimensions, cooling times are centuries to a few millennia. Excess volume of serpentine results in filling of pore spaces, eventually inhibiting fluid flow. Fresh olivine is preserved in lithofacies with initial low porosity, and at the base of the pipe where deeper-level host rocks have low permeability, and the pipe is narrower leading to faster cooling. These predictions are consistent with fresh olivine and serpentine distribution in the Diavik A418 kimberlite pipe, (NWT, Canada) and with features of kimberlites of the Yakutian province in Russia affected by influx of ground water brines. Fast reactions and increases in the volume of solid products compared to the reactants result in self-sealing and low water-rock ratios (estimated at alteration of kimberlites predominantly by interactions with external non-magmatic fluids.

  14. Asthenospheric kimberlites: Volatile contents and bulk compositions at 7 GPa

    Science.gov (United States)

    Stamm, Natalia; Schmidt, Max W.

    2017-09-01

    During ascent, kimberlites react with the lithospheric mantle, entrain and assimilate xenolithic material, loose volatiles and suffer from syn- and post-magmatic alteration. Consequently, kimberlite rocks deviate heavily from their primary melt. Experiments at 7 GPa, 1300-1480 °C, 10-30 wt% CO2 and 0.46 wt% H2O on a proposed primitive composition from the Jericho kimberlite show that saturation with a lherzolitic mineral assemblage occurs only at 1300-1350 °C for a carbonatitic melt with 35 wt% CO2. At asthenospheric temperatures of >1400 °C, where the Jericho melt stays kimberlitic, this composition saturates only in low-Ca pyroxene, garnet and partly olivine. We hence forced the primitive Jericho kimberlite into multiple saturation with a lherzolitic assemblage by adding a compound peridotite. Saturation in olivine, low- and high-Ca pyroxene and garnet was obtained at 1400-1650 °C (7 GPa), melts are kimberlitic with 18-29 wt% SiO2 + Al2O3, 22.1-24.6 wt% MgO, 15-27 wt% CO2 and 0.4-7.1 wt% H2O; with a trade-off of H2O vs. CO2 and temperature. Melts in equilibrium with high-Ca pyroxene with typical mantle compositions have ≥2.5 wt% Na2O, much higher than the commonly proposed 0.1-0.2 wt%. The experiments allow for a model of kimberlite origin in the convective upper mantle, which only requires mantle upwelling that causes melting at the depth where elemental carbon (in metal, diamond or carbide) converts to CO2 (at ∼250 km). If primary melts leading to kimberlites contain a few wt% H2O, then adiabatic temperatures of 1400-1500 °C would yield asthenospheric mantle melts that are kimberlitic (>18 wt% SiO2 + Al2O3) but not carbonatitic (<10 wt% SiO2 + Al2O3) in composition, carbonatites only forming 100-200 °C below the adiabat. These kimberlites represent small melt fractions concentrating CO2 and H2O and then acquire part of their chemical signature by assimilation/fractionation during ascent in the subcratonic lithosphere.

  15. How unique is the Udachnaya-East kimberlite? Comparison with kimberlites from the Slave Craton (Canada) and SW Greenland

    Science.gov (United States)

    Kamenetsky, Vadim S.; Kamenetsky, Maya B.; Weiss, Yakov; Navon, Oded; Nielsen, Troels F. D.; Mernagh, Terrence P.

    2009-11-01

    The origin of alkali carbonates and chlorides in the groundmass of unaltered Udachnaya-East kimberlites in Siberia is still controversial. Contrary to existing dogma that the Udachnaya-East kimberlite was either contaminated by the crustal sediments or platform brines, magmatic origin of the groundmass assemblage has been proposed on the basis of melt immiscibility textures, melt inclusion studies, and strontium and neon isotope compositions. We further tested the idea of alkali- and chlorine enrichment of the kimberlite parental melt by studying olivine-hosted melt inclusions and secondary serpentine in kimberlites from the Slave Craton, Canada (Gahcho Kué, Jericho, Aaron and Leslie pipes) and southern West Greenland (Majuagaa dyke). Host olivine phenocrysts closely resemble groundmass olivine from the Udachnaya-East kimberlite in morphology, compositions (high-Fo, low-Ca), complex zoning with cores of varying shapes and compositions and rims of constant Fo. Melt inclusions in olivine consist of several translucent and opaque daughter phases and vapour bubble(s). The daughter crystals studied in unexposed inclusions by laser Raman spectroscopy and in carefully exposed inclusions by WDS-EDS are represented by Na-K chlorides, calcite, dolomite, magnesite, Ca-Na, Ca-Na-K and Ca-Mg-Ba carbonates, bradleyite Na 3 Mg(CO 3)(PO 4), K-bearing nahpoite Na 2(HPO 4), apatite, phlogopite and tetraferriphlogopite, unidentified sulphates, Fe sulphides, djerfisherite, pyrochlore (Na,Ca) 2Nb 2O 6(OH,F), monticellite, Cr-spinel and Fe-Ti oxides. High abundances of Na, K (e.g., (Na + K)/Ca = 0.15-0.85) and incompatible trace elements in the melt inclusions are confirmed by LA-ICPMS analysis of individual inclusions. Heating experiments show that melting of daughter minerals starts and completes at low temperatures (~ 100 °C and 600 °C, respectively), further reinforcing the similarity with the Udachnaya-East kimberlite. Serpentine minerals replacing olivine in some of the studied

  16. Origin of carbonate xenoliths in Siddanpalli kimberlites, Southern India

    Science.gov (United States)

    Anand, M.; Osborne, I.; Gilmour, M. A.; Chalapath Rao, N. V.

    2009-04-01

    A number of carbonate xenoliths have been recently discovered from the three kimberlites (designated as SK1, SK2, SK3) of the Siddanpalli kimberlite cluster (SKC; Sridhar et al., 2004) of Southern India. These kimberlites intrude the Precambrian granite-greenstone terrain of Gadwal schist belt of Eastern Dharwar Craton (e.g., Dongre et al., 2008). Rb-Sr phlogopite/whole-rock dating of one of these bodies, SK1, has yielded an age of 1093 ± Ma (Kumar et al. 2007). Previously, Dongre et al. (2008) reported an occurrence of a limestone xenolith from the SK2 kimberlite. Based on petrographic, geochemical, and C and O isotope data these authors suggested a sedimentary origin for the limestone xenolith. However, now we have documented a larger variation in the nature of carbonate material occurring as xenoliths in these kimberlites, ranging from micro-crystalline segregations to well-formed carbonate crystals. Thus, it is likely that a number of sources and/or processes have been involved in their formation. We are in the process of measuring carbon and oxygen isotopic compositions of individual carbonate xenoliths in order to further constrain their origin.

  17. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions

    Science.gov (United States)

    Basu, A.R.; Tatsumoto, M.

    1979-01-01

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 ?? 106 to 1300 ?? 106 years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. Copyright ?? 1979 AAAS.

  18. Spatial Patterns in Distribution of Kimberlites: Relationship to Tectonic Processes and Lithosphere Structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2014-01-01

    weakness zones may control the spatial patterns of kimberlites, but this hypothesis has never been tested by geophysical methods. As the first step in our analysis of tectonic and lithosphere control of kimberlite-type magmatism, we perform a detailed global analysis of the spatial patterns of kimberlites...... of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal...

  19. Chasing the Late Jurassic APW Monster Shift in Ontario Kimberlites

    Science.gov (United States)

    Kent, D. V.; Muttoni, G.; Gee, J. S.; Kjarsgaard, B. A.

    2012-12-01

    A 30° gap was recognized in a composite APW path when global poles from predominantly igneous rocks were assembled in North American coordinates using plate reconstructions (Kent & Irving 2010 JGR). The 'monster shift' occurred between a 160-190 Ma cluster of mean poles at 75-80°N 90-110°E to a 140-145 Ma grouping centered at 60-65°N ~200°E. There are hardly any intermediate igneous poles whereas the rather divergent directions from the Late Jurassic Morrison Formation published by Steiner & Helsley (1975 GSA Bulletin) are subject to adjustments for Colorado Plateau rotation and sedimentary inclination error, neither of which are precisely known for this redbed unit sampled in Colorado. On the other hand, similar large rapid swings have been recognized in the Late Jurassic APW path for Adria (Channell et al. 2010 Paleo3), suggesting a global phenomena. In an effort to fill the data gap between ~145 and 160 Ma, we sampled accessible outcrops/subcrops of kimberlites in the Timiskaming area of Ontario, Canada, that are associated with high precision U-Pb perovskite ages (Heamon & Kjarsgaard 2000 EPSL). We report initial results from two of the intrusions: the 153.6±2.4 Ma Peddie kimberlite from outcrop and the Triple B kimberlite that was accessible by trenching and is assumed to be the same age as the nearby 153.7±1.8 Ma Seed kimberlite as delineated by aeromagnetic surveys and borings. Systematic progressive thermal demagnetization indicated in each unit a dominant characteristic component with unblocking temperatures to 575° that presumably reflect a magnetite carrier that will be checked by further rock magnetic experiments. Samples from the Peddie kimberlite had stable downward (normal polarity) magnetizations whose mean direction gives a paleopole at 73°N 184°E. In contrast, samples from the Triple B kimberlite have upward (reverse polarity) magnetizations with a well-grouped direction whose (north) paleopole is 78°N 197°E, proximal to the Peddie

  20. Spatial patterns in the distribution of kimberlites: relationship to tectonic processes and lithosphere structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2015-01-01

    Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere...... weakness zones may control the spatial patterns of kimberlites, but this hypothesis has never been tested by geophysical methods. As the first step in our analysis of tectonic and lithosphere control of kimberlite-type magmatism, we perform a detailed global analysis of the spatial patterns of kimberlites......, and present the first results. The analysis is based on the assumption that the kimberlite emplacement is a two-stage process, and the two stages are controlled by the crustal and lithospheric mantle rheologies, respectively. Stage 1 includes the first-order, lithosphere-scale process that initiate the rise...

  1. Spatial patterns in the distribution of kimberlites: relationship to tectonic processes and lithosphere structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere...... weakness zones may control the spatial patterns of kimberlites, but this hypothesis has never been tested by geophysical methods. As the first step in our analysis of tectonic and lithosphere control of kimberlite-type magmatism, we perform a detailed global analysis of the spatial patterns of kimberlites......, and present the first results. The analysis is based on the assumption that the kimberlite emplacement is a two-stage process, and the two stages are controlled by the crustal and lithospheric mantle rheologies, respectively. Stage 1 includes the first-order, lithosphere-scale process that initiate the rise...

  2. Spatial patterns in the distribution of kimberlites: relationship to tectonic processes and lithosphere structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2015-01-01

    Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere...... of establishing characteristic scales for the stage 1 and stage 2 processes. To reveal similarities between the Kimberlite data we use the density-based clustering technique, such as density-based spatial clustering of applications with noise (DBSCAN), which is efficient for large data sets, requires one input...

  3. Spatial patterns in the distribution of kimberlites: relationship to tectonic processes and lithosphere structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    Since the discovery of diamonds in kimberlite-type rocks more than a century ago, a number of theories regarding the processes involved in kimberlite emplacement have been put forward to explain the unique properties of kimberlite magmatism. Geological data suggests that pre-existing lithosphere...... of establishing characteristic scales for the stage 1 and stage 2 processes. To reveal similarities between the kimberlite data we use the density-based clustering technique, such as density-based spatial clustering of applications with noise (DBSCAN), which is efficient for large data sets, requires one input...

  4. Origin and source regions of nodule-bearing kimberlites and ultramafic lamprophyres in southern Western Greenland

    DEFF Research Database (Denmark)

    Pilbeam, Llewellyn Howard

    High precision high resolution electron microprobe traverses of olivine grains in the Majuagaa kimberlite sensu stricto from southern West Greenland show that the olivine crystallisation is coupled to digestion of xenocrystic orthopyroxene into the melt. This process was previously suspected...... but unconfirmed in kimberlite sensu stricto magmas. It is here termed digestion fractional crystallisation (DFC) and it is argued that the DFC process may account for much of the global varia-bility in kimberlite compositions. The bulk rock trace element geochemistry of the Majuagaa kimberlite is used...

  5. What olivine, the neglected mineral, tells us about kimberlite petrogenesis

    OpenAIRE

    Arndt, Nicholas; Boullier, Anne-Marie; Clement, J P; Clément, Jean-Pierre; Dubois, M.; Schissel, D.

    2006-01-01

    International audience; We report here the results of a petrographic and geochemical study of remarkably well-preserved kimberlites from the Kangamiut region in Greenland. The samples contain between 5 and 45% of olivine in the form of rounded ''nodules'', each 1 to 5 mm in diameter. Most originally were single crystals but many consist of polycrystalline, monomineralic aggregates. Olivine compositions vary widely from nodule to nodule (from Fo 81-93) but are constant within individual nodule...

  6. Kimberlite emplacement models — The implications for mining projects

    Science.gov (United States)

    Jakubec, Jaroslav

    2008-06-01

    The significance of the emplacement model for kimberlite pipes, or sheets, is commonly recognized in resource geology. However, its importance is not always appreciated in the mine design process. The fact is that knowledge of the orebody geometry, character of the contact zones, internal structures, rock mass competency and distribution of inclusions could directly influence the selection of the underground mining method, pit wall stability, dilution, treatability, and the dewatering strategy. The problems are exacerbated in smaller pipes and narrower sheets, and in more irregular shapes; they are more apparent in underground mining as opposed to open cast. Various kimberlite emplacement processes have a major impact on the nature of the kimberlite orebody and host rocks that will influence the mine design and mining strategy. Failure to understand these processes can adversely affect the economic outcome for developing a mine. It is therefore important to investigate those processes in order to better characterize the mining constraints and risks, and more accurately predict the mine's economic viability.

  7. Garnets from the Camafuca-Camazambo kimberlite (Angola

    Directory of Open Access Journals (Sweden)

    Correia Eugénio A.

    2006-01-01

    Full Text Available This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004 and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10 and Ca-saturated (G9 garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa. The occurrence of diamond stability field garnets (G10D is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.

  8. Growth of bultfonteinite and hydrogarnet in metasomatized basalt xenoliths in the B/K9 kimberlite, Damtshaa, Botswana: insights into hydrothermal metamorphism in kimberlite pipes

    Science.gov (United States)

    Buse, Ben; Schumacher, John C.; Sparks, R. Stephen J.; Field, Matthew

    2010-10-01

    Metamorphic assemblages within Karoo basalt xenoliths, found within volcaniclastic kimberlite of the B/K9 pipe, Damtshaa, Botswana, constrain conditions of kimberlite alteration. Bultfonteinite and chlorite partially replace the original augite-plagioclase assemblage, driven by the serpentinisation of the kimberlite creating strong chemical potential gradients for Si and Mg. Hydrogarnet and serpentine replace these earlier metamorphic assemblages as the deposits cool. The bultfonteinite (ideally Ca2SiO2[OH,F]4) and hydrogarnet assemblages require a water-rich fluid containing F-, and imply hydrothermal alteration dominated by external fluids rather than autometamorphism from deuteric fluids. Bultfonteinite and hydrogarnet are estimated to form at temperatures of ca. 350-250°C, which are similar to those for serpentinisation. Alteration within the B/K9 kimberlite predominantly occurs between 250 and 400°C. We attribute these conditions to increased efficiency of mass transfer and chemical reactions below the critical point of water and a consequence of volume-increasing serpentinisation and metasomatic reactions that take place over this temperature range. A comparison of the B/K9 kimberlite with kimberlites from Venetia, South Africa suggests that the composition and mineralogy of included xenoliths affects the alteration assemblages within kimberlite deposits.

  9. Picroilmenites in Yakutian kimberlites: variations and genetic models

    Science.gov (United States)

    Ashchepkov, I. V.; Alymova, N. V.; Logvinova, A. M.; Vladykin, N. V.; Kuligin, S. S.; Mityukhin, S. I.; Downes, H.; Stegnitsky, Yu. B.; Prokopiev, S. A.; Salikhov, R. F.; Palessky, V. S.; Khmel'nikova, O. S.

    2014-09-01

    Major and trace element variations in picroilmenites from Late Devonian kimberlite pipes in Siberia reveal similarities within the region in general, but show individual features for ilmenites from different fields and pipes. Empirical ilmenite thermobarometry (Ashchepkov et al., 2010), as well as common methods of mantle thermobarometry and trace element geochemical modeling, shows long compositional trends for the ilmenites. These are a result of complex processes of polybaric fractionation of protokimberlite melts, accompanied by the interaction with mantle wall rocks and dissolution of previous wall rock and metasomatic associations. Evolution of the parental magmas for the picroilmenites was determined for the three distinct phases of kimberlite activity from Yubileynaya and nearby Aprelskaya pipes, showing heating and an increase of Fe# (Fe# = Fe / (Fe + Mg) a.u.) of mantle peridotite minerals from stage to stage and splitting of the magmatic system in the final stages. High-pressure (5.5-7.0 GPa) Cr-bearing Mg-rich ilmenites (group 1) reflect the conditions of high-temperature metasomatic rocks at the base of the mantle lithosphere. Trace element patterns are enriched to 0.1-10/relative to primitive mantle (PM) and have flattened, spoon-like or S- or W-shaped rare earth element (REE) patterns with Pb > 1. These result from melting and crystallization in melt-feeding channels in the base of the lithosphere, where high-temperature dunites, harzburgites and pyroxenites were formed. Cr-poor ilmenite megacrysts (group 2) trace the high-temperature path of protokimberlites developed as result of fractional crystallization and wall rock assimilation during the creation of the feeder systems prior to the main kimberlite eruption. Inflections in ilmenite compositional trends probably reflect the mantle layering and pulsing melt intrusion during melt migration within the channels. Group 2 ilmenites have inclined REE enriched patterns (10-100)/PM with La / Ybn ~ 10

  10. Geology of the Mwadui kimberlite, Shinyanga district, Tanzania

    Science.gov (United States)

    Stiefenhofer, J.; Farrow, D. J.

    2004-09-01

    The Mwadui pipe represents the largest diamondiferous kimberlite ever mined and is an almost perfectly preserved example of a kimberlitic crater in-fill, albeit without the tuff ring. The geology of Mwadui can be subdivided into five geological units, viz. the primary pyroclastic kimberlite (PK), re-sedimented volcaniclastic kimberlite deposits (RVK), granite breccias (subdivided into two units), the turbidite deposits, and the yellow shales listed in approximate order of formation. The PK can be further subdivided into two units—lithic-rich ash and lapilli tuffs which dominate the succession, and lithic-poor juvenile-rich ash and lapilli tuffs. The lower crater is well bedded down to at least 684 m from present surface (extent of current drill data). The bedding is defined by the presence of juvenile-rich lapilli tuffs vs. lithic-rich lapilli tuffs, and the systematic variation in granite content and clast size within much of the lithic-rich lapilli tuffs. Four distinct types of bedding have been identified in the pyroclastic deposits. Diffuse zones characterised by increased granite abundance and size, and upward-fining units, represent the dominant types throughout the deposit. Lateral heterogeneity was observed, in addition to the vertical changes, suggesting that the eruption was quite heterogeneous, or that more than one vent may have been present. The continuous nature of the bedding in the pyroclastic material and the lack of ash-partings suggest deposition from a high concentration (ejecta), sustained eruption column at times, e.g. the massive, very diffusely stratified deposits. The paucity of tractional bed forms suggest near vertical particle trajectories, i.e. a clear air-fall component, but the poorly sorted, matrix-supported nature of the deposits suggest that pyroclastic flow and/or surge processes may also have been active during the eruption. Available diamond sampling data were examined and correlated with the geology. Data derive from the old

  11. Spatial Patterns in Distribution of Kimberlites: Relationship to Tectonic Processes and Lithosphere Structure

    DEFF Research Database (Denmark)

    Chemia, Zurab; Artemieva, Irina; Thybo, Hans

    2014-01-01

    of kimberlite melts through the lithospheric mantle, which forms the major pipe. Stage 2 (second-order process) begins when the major pipe splits into daughter sub-pipes (tree-like pattern) at crustal depths. We apply cluster analysis to the spatial distribution of all known kimberlite fields with the goal...

  12. The geology of kimberlite pipes of the Ekati property, Northwest Territories, Canada

    Science.gov (United States)

    Nowicki, Tom; Crawford, Barbara; Dyck, Darren; Carlson, Jon; McElroy, Ross; Oshust, Peter; Helmstaedt, Herb

    2004-09-01

    This paper reviews key characteristics of kimberlites on the Ekati property, NWT, Canada. To date 150 kimberlites have been discovered on the property, five of which are mined for diamonds. The kimberlites intrude Archean basement of the central Slave craton. Numerous Proterozoic diabase dykes intrude the area. The Precambrian rocks are overlain by Quaternary glacial sediments. No Phanerozoic rocks are present. However, mudstone xenoliths and disaggregated sediment within the kimberlites indicate that late-Cretaceous and Tertiary cover (likely ash) and variable amounts of exotic sediment (primarily mud), with minor amounts of xenolithic wall-rock material (generally ash. Diamond distribution within the kimberlites reflects the amount and nature of mantle material sampled by individual kimberlite phases, but is modified considerably by eruption and depositional processes. The characteristics of the Ekati kimberlites are consistent with a two-stage emplacement process: (1) explosive eruption/s causing vent clearing followed by formation of a significant tephra rim/cone of highly fragmented, olivine-enriched juvenile material with varying amounts of kimberlitic ash and surface sediments (predominantly mud); and (2) infilling of the vent by direct deposition from the eruption column and/or resedimentation of crater rim materials. The presence of less fragmented, juvenile-rich PVK in the lower portions of certain pipes and the intrusion of large volumes of MK to shallow levels in some bodies suggest emplacement of relatively volatile-depleted, less explosive kimberlite in the later stages of pipe formation and/or filling. Explosive devolatilisation of CO 2-rich kimberlite magma is interpreted to have been the dominant eruption mechanism, but phreatomagmatism is thought to have played a role and, in certain cases, may have been dominant.

  13. Multi-stage kimberlite evolution tracked in zoned olivine from the Benfontein sill, South Africa

    Science.gov (United States)

    Howarth, Geoffrey H.; Taylor, Lawrence A.

    2016-10-01

    Olivine is the dominant mineral present in kimberlite magmas; however, due to the volatile-rich nature of most kimberlites, they rarely survive late-stage serpentinisation. Here we present major and trace element data for a rare example of ultra-fresh olivine in a macrocrystic calcite kimberlite from the Benfontein kimberlite sill complex. Olivines are characterised by xenocrystic cores surrounded by multiple growth zones representing melt crystallisation and late-stage equilibration. Two distinct core populations are distinguished: Type 1) low Fo (88-89), Ni-rich, Ca- and Na-rich cores, interpreted here to be the result of carbonate-silicate metasomatism potentially as part of the earliest stages of kimberlite magmatism, and Type 2) high Fo (91-93), Ni-rich, low-Ca cores derived from a typical garnet peridotite mantle source. In both cases, the cores have transitional margins (Fo89-90) representing equilibration with a proto-kimberlite melt. Trace element concentrations, in particular Cr, of these transition zones suggest formation of the proto-kimberlite melt through assimilation of orthopyroxene from the surrounding garnet peridotite lithology. Trace element trends in the surrounding melt-zone olivine (Fo87-90) suggest evolution of the kimberlite through progressive olivine crystallisation. The final stages of olivine growth are represented by Fe-rich (Fo85) and P-rich olivine indicating kimberlite evolution to mafic compositions. Fine (evolution back to Fe-poor carbonatitic melts. We present a step-by-step model for kimberlite magma genesis and evolution from mantle to crust tracked by the chemistry of olivines in the Benfontein kimberlite. These steps include early stages of metasomatism and mantle assimilation followed by direct crystallisation of the kimberlite melt and late-stage equilibration with the evolved carbonatitic residual liquids. The Ca contents of the Type 1 xenocrystic olivines are the highest yet measured for mantle olivines, and do not

  14. Mineral inclusions in sublithospheric diamonds from Collier 4 kimberlite pipe, Juina, Brazil: subducted protoliths, carbonated melts and primary kimberlite magmatism

    Science.gov (United States)

    Bulanova, Galina P.; Walter, Michael J.; Smith, Chris B.; Kohn, Simon C.; Armstrong, Lora S.; Blundy, Jon; Gobbo, Luiz

    2010-10-01

    We report on a suite of diamonds from the Cretaceous Collier 4 kimberlite pipe, Juina, Brazil, that are predominantly nitrogen-free type II crystals showing complex internal growth structures. Syngenetic mineral inclusions comprise calcium- and titanium-rich phases with perovskite stoichiometry, Ca-rich majoritic-garnet, clinopyroxene, olivine, TAPP phase, minerals with stoichiometries of CAS and K-hollandite phases, SiO2, FeO, native iron, low-Ni sulfides, and Ca-Mg-carbonate. We divide the diamonds into three groups on the basis of the carbon isotope compositions (δ13C) of diamond core zones. Group 1 diamonds have heavy, mantle-like δ13C (-5 to -10‰) with mineral inclusions indicating a transition zone origin from mafic protoliths. Group 2 diamonds have intermediate δ13C (-12 to -15‰), with inclusion compositions indicating crystallization from near-primary and differentiated carbonated melts derived from oceanic crust in the deep upper mantle or transition zone. A 206Pb/238U age of 101 ± 7 Ma on a CaTiSi-perovskite inclusion (Group 2) is close to the kimberlite emplacement time (93.1 ± 1.5 Ma). Group 3 diamonds have extremely light δ13C (-25‰), and host inclusions have compositions akin to high-pressure-temperature phases expected to be stable in pelagic sediments subducted to transition zone depths. Collectively, the Collier 4 diamonds and their inclusions indicate multi-stage, polybaric growth histories in dynamically changing chemical environments. The young inclusion age, the ubiquitous chemical and isotopic characteristics indicative of subducted materials, and the regional tectonic history, suggest a model in which generation of sublithospheric diamonds and their inclusions, and the proto-kimberlite magmas, are related genetically, temporally and geographically to the interaction of subducted lithosphere and a Cretaceous plume.

  15. Hydrostatic extrusion of magnesium alloys

    NARCIS (Netherlands)

    Sillekens, W.H.; Bohlen, J.

    2012-01-01

    This chapter deals with the capabilities and limitations of the hydrostatic extrusion process for the manufacturing of magnesium alloy sections. Firstly, the process basics for the hydrostatic extrusion of materials in general and of magnesium in particular are introduced. Next, some recent research

  16. Possibility of Extrusion of Wood Powders

    National Research Council Canada - National Science Library

    MIKI, Tsunehisa; TAKAKURA, Norio; IIZUKA, Takashi; YAMAGUCHI, Katsuhiko; KANAYAMA, Kouzou

    2003-01-01

    .... Effects of extrusion temperature, extrusion ratio, moisture content and particle size of the mixed wood powders on the flow characteristics, bending strength, hardness and bulk density of extruded...

  17. Sulfides in diamonds and in xenoliths from kimberlite pipes of Yakutiia

    Science.gov (United States)

    Bulanova, Galina P.; Spetsius, Zdislav V.; Leskova, Nelli V.

    The characteristics of sulfides from diamonds and xenoliths are compared using literature data on the mineralogy of sulfides in diamonds and in deep-seated xenoliths from kimberlite pipes. Results are presented on the Fe-Ni-Cu-Co-S mineral systems of mantle associations, sulfide inclusions in diamonds and megacrystals of kimberlite rocks, and minerals of the Fe-Ni-Cu-Co-S system in mantle xenoliths from kimberlite pipes. Particular consideration is given to the nature of sulfide mineralization in mantle xenoliths and diamonds.

  18. Origin and diamond prospectivity of Mesoproterozoic kimberlites from the Narayanpet field, Eastern Dharwar Craton, southern India

    DEFF Research Database (Denmark)

    Chalapathi Rao, N.V.; Paton, Chad; Lehmann, B.

    2012-01-01

    The Mesoproterozoic Narayanpet Kimberlite Field (NKF) is located ~200km north of the well-known Wajrakarur Kimberlite Field (WKF) in the Eastern Dharwar Craton, southern India. Whereas a majority of the WKF occurrences are diamondiferous and contain mantle xenoliths and xenocrysts, their paucity ......-wide, indicates that redox conditions were favourable for diamond prospectivity, and that magmatic emplacement could, instead, have played a major role in their low diamond potential. © 2011 John Wiley & Sons, Ltd.....

  19. Pristine Early Eocene Wood Buried Deeply in Kimberlite from Northern Canada

    OpenAIRE

    Wolfe, Alexander P.; Csank, Adam Z.; Reyes, Alberto V.; McKellar, Ryan C.; Ralf Tappert; Karlis Muehlenbachs

    2012-01-01

    We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma), revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identificatio...

  20. The crater-facies kimberlite system of Tokapal, Bastar District, Chhattisgarh, India

    Science.gov (United States)

    Mainkar, Datta; Lehmann, Bernd; Haggerty, Stephen E.

    2004-09-01

    Discovery of diamondiferous kimberlites in the Mainpur Kimberlite Field, Raipur District, Chhattisgarh in central India, encouraged investigation of similar bodies in other parts of the Bastar craton. The earlier known Tokapal ultramafic intrusive body, located beyond the 19-km milestone in Tokapal village along the Jagdalpur-Geedam road, was reinterpreted as crater-facies kimberlite. Its stratigraphic position in the Meso-Neoproterozoic intracratonic sedimentary Indravati basin makes it one of the oldest preserved crater-facies kimberlite systems. Ground and limited subsurface data (dug-, tube-wells and exploratory boreholes) have outlined an extensive surface area (>550 ha) of the kimberlite. The morphological and surface color features of this body on enhanced satellite images suggest that there is a central feeder surrounded by a collar and wide pyroclastic apron. Exploration drilling indicates that the central zone probably corresponds to a vent overlain by resedimented volcaniclastic (epiclastic) rocks that are surrounded by a 2-km-wide spread of pyroclastic rocks (lapilli tuff, tuff/ash beds and volcaniclastic breccia). Drill-holes also reveal that kimberlitic lapilli tuffs and tuffs are sandwiched between the Kanger and Jagdalpur Formations and also form sills within the sedimentary sequence of the Indravati basin. The lapilli tuffs are commonly well stratified and display slumping. Base surges and lava flows occur in the southern part of the Tokapal system. The geochemistry and petrology of the rock correspond to average Group I kimberlite with a moderate degree of contamination. However, the exposed rock is intensely weathered and altered with strong leaching of mobile elements (Ba, Rb, Sr). Layers of vesicular fine-grained glassy material represent kimberlitic lava flows. Tuffs containing juvenile lapilli with pseudomorphed olivine macrocrysts are set in a talc-serpentine-carbonate matrix with locally abundant spinel and sphene. Garnet has not been

  1. Emplacement temperatures of pyroclastic and volcaniclastic deposits in kimberlite pipes in southern Africa

    Science.gov (United States)

    Fontana, Giovanni; Mac Niocaill, Conall; Brown, Richard J.; Sparks, R. Stephen J.; Field, Matthew

    2011-10-01

    Palaeomagnetic techniques for estimating the emplacement temperatures of volcanic deposits have been applied to pyroclastic and volcaniclastic deposits in kimberlite pipes in southern Africa. Lithic clasts were sampled from a variety of lithofacies from three pipes for which the internal geology is well constrained (the Cretaceous A/K1 pipe, Orapa Mine, Botswana, and the Cambrian K1 and K2 pipes, Venetia Mine, South Africa). The sampled deposits included massive and layered vent-filling breccias with varying abundances of lithic inclusions, layered crater-filling pyroclastic deposits, talus breccias and volcaniclastic breccias. Basalt lithic clasts in the layered and massive vent-filling pyroclastic deposits in the A/K1 pipe at Orapa were emplaced at >570°C, in the pyroclastic crater-filling deposits at 200-440°C and in crater-filling talus breccias and volcaniclastic breccias at 560°C, although the interpretation of these results is hampered by the presence of Mesozoic magnetic overprints. These temperatures are comparable to the estimated emplacement temperatures of other kimberlite deposits and fall within the proposed stability field for common interstitial matrix mineral assemblages within vent-filling volcaniclastic kimberlites. The temperatures are also comparable to those obtained for pyroclastic deposits in other, silicic, volcanic systems. Because the lithic content of the studied deposits is 10-30%, the initial bulk temperature of the pyroclastic mixture of cold lithic clasts and juvenile kimberlite magma could have been 300-400°C hotter than the palaeomagnetic estimates. Together with the discovery of welded and agglutinated juvenile pyroclasts in some pyroclastic kimberlites, the palaeomagnetic results indicate that there are examples of kimberlites where phreatomagmatism did not play a major role in the generation of the pyroclastic deposits. This study indicates that palaeomagnetic methods can successfully distinguish differences in the

  2. Construction of mantle sequence beneath Yubileynaya kimberlite pipe.

    Science.gov (United States)

    Ashchepkov, I. V.; Vladykin, N. V.; Logvinova, A. M.; Zinchuk, N. N.; Khmelnikova, O. S.; Palessky, S. V.; Nikolaeva, I. V.

    2003-04-01

    Concentrate from Yubileinaya kimberlite pipe (>1000 analyses), Alakite field, Russia, was used for thermobarometry (Nimis, Taylor, 2000; Ryan et al,1997; Ashchepkov, 2002). Cpx geotherm reveal divide at 35 kbars. Three lherzolitic units below this boundary correspond to 40mv/m2 geotherm at the upper part and are close to 35 mv/m2 at the lower part. Upper geotherm part is more dispersed irregularly deviating to LT conditions. The inflection from harzburgite layer low in Cpx to hot ‘asthenospheric’ branch at 1350oC 65 kbar was determined Sequence upper 35 kbars is represented by Ca-Ti- enriched peridotites- pyroxenites judging from Garnet and CPx compositions. Lower unites are represented by NaCr(3-4% each)- rich CPx and Ca-Fe enriched garnets. Garnet reveal also presence of harzburgites in each three units and relic unmetasomitised lherzolite fragments rare occurring in CPx concentrate. Amphiboles in upper part (divided into 8 groups are TiO2 -enriched in the lower part of section and in upper part. Different scheme of isomorphism for- Cr-rich chromites in deep seated units suggest difference in oxygen fugacity and reactied agents. Ilmenite trend consisting from two units: >49% TiO2 Ilm slightly enriched in Al2O3 (~ 0.7 %) while more fractionated Fe- rich ilmenites are Al-poor. Seven ilmenite groups coinciding with amount of spinel groups are likely corresponding to mantle columns layers. Ilmenite megacrystalline suit trace feeding vein system of fractionating pre -eruption kimberlite- carbonatite melts. Accompanied Cr enrichment and Ti rise in spinels and other peridotite minerals in lower units is caused by interaction of melts evolving in chambers and rising in pre-eruption vein system with wall rock peridotites. Division into two parts at 35-40kbar boundary where slab’s PT path crosses dehydration peridotite line (van Keken et al, 2002) probably appeared during lithospheric keel growth accompanied by slab melting and percolation of subduction-related melts

  3. Kimberlite Wall Rock Fragmentation: Venetia K08 Pipe Development

    Science.gov (United States)

    Barnett, W.; Kurszlaukis, S.; Tait, M.; Dirks, P.

    2009-05-01

    Volcanic systems impose powerful disrupting forces on the country rock into which they intrude. The nature of the induced brittle deformation or fragmentation can be characteristic of the volcanic processes ongoing within the volcanic system, but are most typically partially removed or obscured by repeated, overprinting volcanic activity in mature pipes. Incompletely evolved pipes may therefore provide important evidence for the types and stages of wall rock fragmentation, and mechanical processes responsible for the fragmentation. Evidence for preserved stages of fragmentation is presented from a detailed study of the K08 pipe within the Cambrian Venetia kimberlite cluster, South Africa. This paper investigates the growth history of the K08 pipe and the mechanics of pipe development based on observations in the pit, drill core and thin sections, from geochemical analyses, particle size distribution analyses, and 3D modeling. Present open pit exposures of the K08 pipe comprise greater than 90% mega-breccia of country rock clasts (gneiss and schist) with fractal statistics on particle size distributions (PSD) is used to quantify sheared and non- sheared breccia zones. The calculated energy required to form the non-sheared breccia PSD implies an explosive early stage of fragmentation that pre-conditions the rock mass. The pre-conditioning would have been caused by explosions that are either phreatic or phreatomagmatic in nature. The explosions are likely to have been centered on a dyke, or pulses of preceding volatile-fluid phases, which have encountered a local hydrologically active fault. The explosions were inadequate in mechanical energy release (72% of a mine production blast) to eject material from the pipe, and the pipe may not have breached surface. The next stage of fragmentation is interpreted to have been an upward-moving collapse of the pre-conditioned hanging wall of a subterranean volcanic excavation. This would explain the mega-scale layering across

  4. Palaeomagnetic Emplacement Temperature Determinations of Pyroclastic and Volcaniclastic Deposits in Southern African Kimberlite Pipes

    Science.gov (United States)

    Fontana, G.; Mac Niocaill, C.; Brown, R.; Sparks, R. S.; Matthew, F.; Gernon, T. M.

    2009-12-01

    Kimberlites are complex, ultramafic and diamond-bearing volcanic rocks preserved in volcanic pipes, dykes and craters. The formation of kimberlite pipes is a strongly debated issue and two principal theories have been proposed to explain pipe formation: (1) the explosive degassing of magma, and (2) the interaction of rising magma with groundwater (phreatomagmatism). Progressive thermal demagnetization studies are a powerful tool for determining the emplacement temperatures of ancient volcanic deposits and we present the first application of such techniques to kimberlite deposits. Lithic clasts were sampled from a variety of lithofacies, from three pipes for which the internal geology is well constrained (A/K1 pipe, Orapa Mine, Botswana and the K1 and K2 pipes, Venetia Mine, South Africa). The sampled deposits included massive and layered vent-filling breccias with varying abundances of lithic inclusions and layered crater-filling pyroclastic deposits, talus breccias and volcaniclastic breccias. Lithic clasts sampled from layered and massive vent-filling pyroclastic deposits in A/K1 were emplaced at >590° C. Results from K1 and K2 provide a maximum emplacement temperature limit for vent-filling breccias of 420-460° C; and constrain equilibrium deposit temperatures at 300-340° C. Crater-filling volcaniclastic kimberlite breccias and talus deposits from A/K1 were emplaced at ambient temperatures, consistent with infilling of the pipe by post-eruption epiclastic processes. Identified within the epiclastic crater-fill succession is a laterally extensive 15-20 metre thick kimberlite pyroclastic flow deposit emplaced at temperatures of 220-440° C. It overlies the post-eruption epiclastic units and is considered an extraneous pyroclastic kimberlite deposit erupted from another kimberlite vent. The results provide important constraints on kimberlite emplacement mechanisms and eruption dynamics. Emplacement temperatures of >590°C for pipe-filling pyroclastic deposits

  5. OPTIMIZING AN ALUMINUM EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Mohammed Ali Hajeeh

    2013-01-01

    Full Text Available Minimizing the amount of scrap generated in an aluminum extrusion process. An optimizing model is constructed in order to select the best cutting patterns of aluminum logs and billets of various sizes and shapes. The model applied to real data obtained from an existing extrusion factory in Kuwait. Results from using the suggested model provided substantial reductions in the amount of scrap generated. Using sound mathematical approaches contribute significantly in reducing waste and savings when compared to the existing non scientific techniques.

  6. Extrusion processing : effects on dry canine diets

    NARCIS (Netherlands)

    Tran, Q.D.

    2008-01-01

    Keywords: Extrusion, Canine diet, Protein, Lysine, Starch gelatinization, Palatability, Drying. Extrusion cooking is a useful and economical tool for processing animal feed. This high temperature, short time processing technology causes chemical and physical changes that alter the nutritional and

  7. Are diamond-bearing Cretaceous kimberlites related to low-angle subduction beneath western North America?

    Science.gov (United States)

    Currie, Claire A.; Beaumont, Christopher

    2011-02-01

    Diamond-bearing Cretaceous kimberlites of western North America were emplaced 1000-1500 km inboard of the Farallon plate subduction margin and overlap with the development of the Western Interior Seaway, shut-down of the Sierra Nevada arc, and the Laramide orogeny. These events are consistent with a decrease in subduction angle along much of the margin, which placed the subducted Farallon plate in close proximity to the continental interior at the time of kimberlite magmatism. Our numerical models demonstrate that low-angle subduction can result from high plate convergence velocities and enhanced westward motion of North America. Further, rapid subduction allows hydrous minerals to remain stable within the cool interior of the subducting plate to more than 1200 km from the trench. Destabilization of these minerals provides a fluid source that can infiltrate the overlying material, potentially triggering partial melting and kimberlite/lamproite magmatism.

  8. Pristine Early Eocene wood buried deeply in kimberlite from northern Canada.

    Directory of Open Access Journals (Sweden)

    Alexander P Wolfe

    Full Text Available We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma, revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia (Cupressaceae. The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ(18O and δ(2H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12-17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information.

  9. Pristine Early Eocene wood buried deeply in kimberlite from northern Canada.

    Science.gov (United States)

    Wolfe, Alexander P; Csank, Adam Z; Reyes, Alberto V; McKellar, Ryan C; Tappert, Ralf; Muehlenbachs, Karlis

    2012-01-01

    We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma), revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia (Cupressaceae). The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ(18)O and δ(2)H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12-17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information.

  10. The reactive extrusion of thermoplastic polyurethane

    NARCIS (Netherlands)

    Verhoeven, Vincent Wilhelmus Andreas

    2006-01-01

    The objective of this thesis was to increase the understanding of the reactive extrusion of thermoplastic polyurethane. Overall, several issues were identified: • Using a relative simple extrusion model, the reactive extrusion process can be described. This model can be used to further investigate a

  11. Are diamond-bearing Cretaceous kimberlites related to shallow-angle subduction beneath western North America?

    Science.gov (United States)

    Currie, C. A.; Beaumont, C.

    2009-05-01

    The origin of deep-seated magmatism (in particular, kimberlites and lamproites) within continental plate interiors remains enigmatic in the context of plate tectonic theory. One hypothesis proposes a relationship between kimberlite occurrence and lithospheric subduction, such that a subducting plate releases fluids below a continental craton, triggering melting of the deep lithosphere and magmatism (Sharp, 1974; McCandless, 1999). This study provides a quantitative evaluation of this hypothesis, focusing on the Late Cretaceous- Eocene (105-50 Ma) kimberlites and lamproites of western North America. These magmas were emplaced along a corridor of Archean and Proterozoic lithosphere, 1000-1500 km inboard of the plate margin separating the subducting Farallon Plate and continental North America Plate. Kimberlite-lamproite magmatism coincides with tectonic events, including the Laramide orogeny, shut-down of the Sierra Nevada arc, and eastward migration of volcanism, that are commonly attributed to a change in Farallon Plate geometry to a shallow-angle trajectory (trench, where they may break down and release fluids that infiltrate the overlying craton lithosphere. This is supported by geochemical studies that indicate metasomatism of the Colorado Plateau and Wyoming craton mantle lithosphere by an aqueous fluid and/or silicate melt with a subduction signature. Through Cretaceous shallow-angle subduction, the Farallon Plate was in a position to mechanically and chemically interact with North American craton lithosphere at the time of kimberlite-lamproite magmatism, making the subduction hypothesis a viable mechanism for the genesis of these magmas. REFERENCES: McCandless, T.E., Proceedings of the 7th International Kimberlite Conference, v.2, pp.545-549, 1999; Sharp, W.E., Earth Planet. Sci. Lett., v.21, pp.351-354, 1974.

  12. Stability of vitamins during extrusion.

    Science.gov (United States)

    Riaz, Mian N; Asif, Muhammad; Ali, Rashida

    2009-04-01

    Vitamins (fat and water soluble) are vital food ingredients for healthy living, required by our bodies for normal metabolism. These are present in most natural food in small quantities, but when we process food through thermal processing methods (especially extrusion) a reasonable amount of the present vitamins are lost. During extrusion, factors like barrel temperature, screw rpm, moisture of ingredients, die diameter, and throughput affect the retention of vitamins in food and feed. The vitamins most sensitive to the extrusion process are vitamin A and vitamin E from fat-soluble vitamins, and vitamin C, B(1), and folic acid from water-soluble vitamins. The other vitamins of the B group, such as B(2), B(6), B(12), niacin, Ca-pantothenate, and biotin, are stable. Vitamin E itself or in its complex form is quite unstable during processing and even in storage of extruded food. Ascorbic acid directly added or coated with fat and then added to feed during extrusion is also very unstable. Vitamins A, C, D, and E are also sensitive to oxidation, so these vitamins have minimum retention during storage of extruded food.

  13. Effect of extrusion ratio on coating extrusion of Pb-GF composite wire by numerical simulation and experimental investigation

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; SUN Hong-fei; FANG Wen-bin

    2009-01-01

    The extrusion ratio is one of the key parameters for manufacturing the lead-glass fiber (Pb-GF) composite wire by coating extrusion. The effect of extrusion ratio on coating extrusion of Pb-GF composite wire was studied by finite element numerical simulation with the use of the DEFOEM simulation software. The simulation result shows that the higher the extrusion ratio, the higher the effective stress that the glass fiber bears during extrusion. It is also observed that the extrusion force increases with the increase of the extrusion ratio. The extrusion experiment of Pb-GF composite wire reveals that extrusion ratio is changed by changing the quantity of glass fiber and composite diameter. The rule that increasing the extrusion ratio enhances the coating speed limit suggests that the load on the glass fiber increases with increasing extrusion ratio. Both the simulation and the extrusion experiments show that the extrusion force increases with increasing extrusion ratio.

  14. Are Majhgawan-Hinota pipe rocks truly group-I kimberlite?

    Indian Academy of Sciences (India)

    Ravi Shanker; S Nag; A Ganguly; A Absar; B P Rawat; G S Singh

    2001-03-01

    The diamond bearing pipe rocks in Majhgawan–Hinota (more than four pipes) occur as intrusives in sandstones of Kaimur Group. These Proterozoic (974 ± 30–1170 ± 20 Ma) intrusive rocks, occupying the southeastern margin of Aravalli craton, were called as `micaceous kimberlite' in tune with the reported kimberlite occurrences from other parts of the world. Judging from the definition of kimberlite, as approved by the IUGS Subcommission on Systematics of Igneous Rocks, it is not justified to call these rocks as `micaceous kimberlite'. Rather the mineralogical assemblages such as absence of typomorphic mineral monticellite (primary), abundance of phlogopite cognate, frequent presence of barite and primary carbonate mostly as calcite coupled with ultrapotassic and volatile-rich (dominantly H2O) nature and high concentration of incompatible elements (such as Ba, Zr, Th, U), low Th/U ratios, low REE and no Eu-anomaly clearly indicate a close similarity with that of South African orangeites. Thus orangeites of Proterozoic age occur outside the Kaapvaal craton of South Africa which are much younger (200 Ma to 110 Ma) in age.

  15. Diamond resorption features as a new method for examining conditions of kimberlite emplacement

    Science.gov (United States)

    Fedortchouk, Yana

    2015-10-01

    The study develops a new approach utilizing parameters of trigonal etch pits on diamond crystals to infer the conditions of diamond residence in kimberlite magma. Diamond crystals from dissolution experiments conducted at 1 GPa and 1150-1350 °C in the presence of H2O-rich or CO2-rich fluid were studied with atomic force microscopy (AFM). The AFM data of resorbed diamond surfaces show that much deeper surface relief was produced in CO2 fluid. It also clearly distinguishes the profiles of the trigonal etch pits forming regular flat-bottomed trigons in H2O fluid, and round- or pointed-bottomed trigons in CO2 fluid. The relationship between the diameter and the depth of the trigonal pits is found to be another important indicator of the fluid composition. Dissolution in H2O fluid develops trigons with constant diameter and variable depth where the diameter increases with temperature. Trigons developed in CO2 fluid have a large range of diameters showing a strong positive correlation with the depth. The developed criteria applied to the natural diamond crystals from three Ekati Mine kimberlites indicate significant variation in CO2-H2O ratio and temperature of their magmatic fluid. This conclusion based on diamond resorption agrees with the mineralogy of microphenocrysts and groundmass of the studied kimberlites offering new method to study crystallization conditions of kimberlite magma.

  16. Hot Extrusion of Aluminum Chips

    Science.gov (United States)

    Tekkaya, A. Erman; Güley, Volkan; Haase, Matthias; Jäger, Andreas

    The process of hot extrusion is a promising approach for the direct recycling of aluminum machining chips to aluminum profiles. The presented technology is capable of saving energy, as remelting of aluminum chips can be avoided. Depending on the deformation route and process parameters, the chip-based aluminum extradates showed mechanical properties comparable or superior to cast aluminum billets extruded under the same conditions. Using different metal flow schemes utilizing different extrusion dies the mechanical properties of the profiles extruded from chips can be improved. The energy absorption capacity of the profiles the rectangular hollow profiles extruded from chips and as-cast billets were analyzed using the drop hammer test set-up. The formability of the profiles extruded from chips and as-cast material were compared using tube bending tests in a three-roller-bending machine.

  17. Extrusion of ECC-Material

    DEFF Research Database (Denmark)

    Stang, Henrik; Li, Victor C.

    1999-01-01

    in recent years at Department of Civil and Envirionmetal Engineering, University of Michigan. These materials have been developed with the special aim of producing high performance , strain hardening materials with low volume concentrations of short fibers in a cementitious material.ECC material spcimens...... have until now been produced by traditional casting processes. In the present paper results from a recent collaborative reserach project are documented - demonstrating that ECC materials can be extruded in the process referred to above.......An extrusion process especially designed for extrusion of pipes made from fiber reinforced cementitious materials has been developed at Department of Structural Engineering and Materials at the Technical University of DenmarkEngineered Cementitious Composite (ECC) materials have been developed...

  18. Petrogenesis of the crater-facies Tokapal kimberlite pipe, Indrāvati Basin, Central India

    Institute of Scientific and Technical Information of China (English)

    N.V. Chalapathi Rao; B. Lehmann; B.K. Panwar; Alok Kumar; D. Mainkar

    2014-01-01

    New geochemical data of the crater-facies Tokapal kimberlite system sandwiched between the lower and upper stratigraphic horizons of the Mesoproterozoic Indrāvati Basin are presented. The kimberlite has been subjected to extensive and pervasive low-temperature alteration. Spinel is the only primary phase identifiable, while olivine macrocrysts and juvenile lapilli are largely pseudomorphed (talc-serpentine-carbonate alteration). However, with the exception of the alkalies, major element oxides display systematic fractionation trends; likewise, HFSE patterns are well correlated and allow petrogenetic interpretation. Various crustal contamination indices such as (SiO2 þ Al2O3 þ Na2O)/(MgO þ K2O) and Si/Mg are close to those of uncontaminated kimberlites. Similar La/Yb (79e109) of the Tokapal samples with those from the kimberlites of Wajrakarur (73e145) and Narayanpet (72e156), Eastern Dharwar craton, southern India implies a similarity in their genesis. In the discriminant plots involving HFSE the Tokapal samples display strong affinities to Group II kimberlites from southern Africa and central India as well as to‘transitional kimberlites’ from the Eastern Dharwar craton, southern India, and those from the Prieska and Kuruman provinces of southern Africa. There is a striking similarity in the depleted-mantle (TDM) Nd model ages of the Tokapal kimberlite system, Bastar craton, the kimberlites from NKF and WKF, Eastern Dharwar craton, and the Majhgawan diatreme, Bundelkhand craton, with the emplacement age of some of the lamproites from within and around the Palaeo-Mesoproterozoic Cuddapah basin, southern India. These similar ages imply a major tectonomagmatic event, possibly related to the break-up of the supercontinent of Columbia, at 1.3e1.5 Ga across the three cratons. The ‘transitional’ geochemical features displayed by many of the Mesoproterozoic potassic-ultrapotassic rocks, across these Indian cratons are inferred to be memories of the

  19. Petrogenesis of the crater-facies Tokapal kimberlite pipe, Indrāvati Basin, Central India

    Directory of Open Access Journals (Sweden)

    N.V. Chalapathi Rao

    2014-11-01

    Full Text Available New geochemical data of the crater-facies Tokapal kimberlite system sandwiched between the lower and upper stratigraphic horizons of the Mesoproterozoic Indrāvati Basin are presented. The kimberlite has been subjected to extensive and pervasive low-temperature alteration. Spinel is the only primary phase identifiable, while olivine macrocrysts and juvenile lapilli are largely pseudomorphed (talc-serpentine-carbonate alteration. However, with the exception of the alkalies, major element oxides display systematic fractionation trends; likewise, HFSE patterns are well correlated and allow petrogenetic interpretation. Various crustal contamination indices such as (SiO2 + Al2O3 + Na2O/(MgO + K2O and Si/Mg are close to those of uncontaminated kimberlites. Similar La/Yb (79–109 of the Tokapal samples with those from the kimberlites of Wajrakarur (73–145 and Narayanpet (72–156, Eastern Dharwar craton, southern India implies a similarity in their genesis. In the discriminant plots involving HFSE the Tokapal samples display strong affinities to Group II kimberlites from southern Africa and central India as well as to ‘transitional kimberlites’ from the Eastern Dharwar craton, southern India, and those from the Prieska and Kuruman provinces of southern Africa. There is a striking similarity in the depleted-mantle (TDM Nd model ages of the Tokapal kimberlite system, Bastar craton, the kimberlites from NKF and WKF, Eastern Dharwar craton, and the Majhgawan diatreme, Bundelkhand craton, with the emplacement age of some of the lamproites from within and around the Palaeo-Mesoproterozoic Cuddapah basin, southern India. These similar ages imply a major tectonomagmatic event, possibly related to the break-up of the supercontinent of Columbia, at 1.3–1.5 Ga across the three cratons. The ‘transitional’ geochemical features displayed by many of the Mesoproterozoic potassic-ultrapotassic rocks, across these Indian cratons are inferred to be

  20. Etching Behavior of Aluminum Alloy Extrusions

    Science.gov (United States)

    Zhu, Hanliang

    2014-11-01

    The etching treatment is an important process step in influencing the surface quality of anodized aluminum alloy extrusions. The aim of etching is to produce a homogeneously matte surface. However, in the etching process, further surface imperfections can be generated on the extrusion surface due to uneven materials loss from different microstructural components. These surface imperfections formed prior to anodizing can significantly influence the surface quality of the final anodized extrusion products. In this article, various factors that influence the materials loss during alkaline etching of aluminum alloy extrusions are investigated. The influencing variables considered include etching process parameters, Fe-rich particles, Mg-Si precipitates, and extrusion profiles. This study provides a basis for improving the surface quality in industrial extrusion products by optimizing various process parameters.

  1. Chemical changes during extrusion cooking. Recent advances.

    Science.gov (United States)

    Camire, M E

    1998-01-01

    Cooking extruders process a variety of foods, feeds, and industrial materials. Greater flexibility in product development with extruders depends upon understanding chemical reactions that occur within the extruder barrel and at the die. Starch gelatinization and protein denautration are the most important reactions during extrusion. Proteins, starches, and non-starch polysaccharides can fragment, creating reactive molecules that may form new linkages not found in nature. Vitamin stability varies with vitamin structure, extrusion conditions, and food matrix composition. Little is known about the effects of extrusion parameters on phytochemical bioavailability and stability. Reactive extrusion to create new flavor, antioxidant and color compounds will be an area of interest in the future.

  2. A link between geochemistry and geodynamics: carbonatites and kimberlites, Polar Siberia

    Science.gov (United States)

    Rass, Irene

    2010-05-01

    Geophysical evidence indicates that the Moho surface beneath the northern Siberian Platform composes crests (or ranges) up to 14 km high above deeper areas and 50-80 to 150 km wide (Chernyshov and Bokaya, 1983). These ranges at the Moho likely mark ancient rift zones with a thinner crust. More than 70% kimberlites in structures surrounding the Anabar Shield occur along these Moho crests (Kravchenko et al., 1997; Rosen and Kostyuchenko, 1998). Carbonate-rich rocks that compose pipes, along with kimberlites, in kimberlite fields, were recognized as an individual type of carbonatite rocks: kimberlitic carbonatites (Lapin and Marshintsev, 1984). They abound in kimberlite fields of both Paleozoic and Mesozoic age southeast and east of the Anabar Shield. The liquidus temperatures of related kimberlites, determined based on their major-component chemistries, are 1429-1441оC and 1349-1518оC, respectively (Perchuk and Vaganov, 1980). Compared to classic carbonatites in ring complexes, kimberlitic carbonatites are characterized by the lowest relative concentrations of P and Sr, slightly lower REE, and high contents of Cr, Ti, and Zr (Rass, 1998). Mesozoic kimberlitic carbonatites exhibit a dependence of their geochemistry, position relative to the axial zones of the Moho crests, and the temperatures of the associated kimberlites, from the Kuoika to the Lower Kuonamka field: from trace elements between the silicate and carbonate components of the deep-sitting magmas. Their experimentally determined parameters are still scarce (Green, 1994) and obviously insufficient for any conclusions about the physicochemical conditions of the exsolution and/or melting of the parental magmas, so that any empirical dependences the identified in them provide information on the lateral heterogeneity of the mantle material in the northern Siberian Platform. References Chernyshov N.V. and Bokaya L.I., in: Structural Elements of the Earth's Crust and Their Evolution. Nauka, Novosibirsk, 1983

  3. Composition of garnet and clinopyroxene in peridotite xenoliths from the Grib kimberlite pipe, Arkhangelsk diamond province, Russia: Evidence for mantle metasomatism associated with kimberlite melts

    Science.gov (United States)

    Kargin, A. V.; Sazonova, L. V.; Nosova, A. A.; Tretyachenko, V. V.

    2016-10-01

    Here we present major and trace element data for garnet and clinopyroxene from mantle-derived peridotite xenoliths of the Grib kimberlite, the Arkhangelsk diamond province, Russia, and provide new insights into the metasomatic processes that occur within the subcontinental lithospheric mantle (SCLM) during the kimberlite generation and ascent. The mantle xenoliths examined in this study are both coarse and sheared garnet peridotites and consist of olivine, orthopyroxene, clinopyroxene, garnet with minor ilmenite, magnetite, and Cr-spinel. Based on garnet and clinopyroxene composition, two groups of peridotite are recognized. One group contains high-Ti, light rare earth elements (LREE) enriched garnets and low-Mg# clinopyroxenes with low (La/Sm)n (C1 chondrite-normalized) values. This mineral assemblage was in equilibrium with a high-temperature carbonate-silicate metasomatic agent, presumably, a protokimberlite melt. Pressure-temperature (P-T) estimates (T = 1220 °C and P = 70 kbar) suggest that this metasomatic event occurred at the base of the SCLM. Another group contains low-Ti garnet with normal to sinusoidal rare earth elements (REE) distribution patterns and high-Mg# clinopyroxenes with wide range of (La/Sm)n values. The geochemical equilibrium between garnet and clinopyroxene coupled with their REE composition indicates that peridotite mantle experienced metasomatic transformation by injection of a low-Ti (after crystallizations of the ilmenite megacrysts) kimberlite melt that subsequently percolated through a refractory mantle column. Peridotites of this group show a wide range of P-T estimates (T = 730-1070 °C and P = 22-44 kbar). It is suggested that evolution of a kimberlite magma from REE-enriched carbonate-bearing to carbonate-rich ultramafic silicate compositions with lower REE occurs during the ascent and interaction with a surrounding lithospheric mantle, and this process leads to metasomatic modification of the SCLM with formation of both high

  4. Aluminum extrusion with a deformable die

    NARCIS (Netherlands)

    Assaad, W.

    2010-01-01

    Aluminum extrusion process is one of metal forming processes. In aluminum extrusion, a work-piece (billet) is pressed through a die with an opening that closely resembles a desired shape of a profile. By this process, long profiles with an enormous variety of cross-sections can be produced to

  5. Emplacement temperatures of pyroclastic and volcaniclastic deposits in kimberlite pipes in southern Africa

    OpenAIRE

    Fontana, Giovanni; Mac Niocaill, Conall; Brown, Richard J.; Sparks, R. Stephen J.; Field, Matthew

    2011-01-01

    Palaeomagnetic techniques for estimating the emplacement temperatures of volcanic deposits have been applied to pyroclastic and volcaniclastic deposits in kimberlite pipes in southern Africa. Lithic clasts were sampled from a variety of lithofacies from three pipes for which the internal geology is well constrained (the Cretaceous A/K1 pipe, Orapa Mine, Botswana, and the Cambrian K1 and K2 pipes, Venetia Mine, South Africa). The sampled deposits included massive and layered vent-filling brecc...

  6. Spatial, temporal, mineralogical, and compositional variations in Mesozoic kimberlitic magmatism in New York State

    Science.gov (United States)

    Bailey, David G.; Lupulescu, Marian V.

    2015-01-01

    Mesozoic kimberlitic magmatism was geographically widespread across central New York State, and nearly 90 distinct intrusions have been discovered since the first "serpentinite body" was described over 175 years ago. Most of the intrusions are narrow (earth element (REE) concentrations, and the highest 87Sr/86Sr ratios. Intrusion ages for these dikes are poorly constrained, but appear to be contemporaneous with, or slightly older than, the ~ 146 Ma Group A intrusions. All of the kimberlitic intrusions in central New York State have initial Sr and Nd isotope ratios close to bulk earth. This fact, combined with the observed macrocryst assemblages and incompatible trace element ratios, indicates that these magmas were derived primarily from an asthenospheric, garnet lherzolite source. Episodic intrusion of small volume, volatile-rich kimberlitic magmas into the Paleozoic sedimentary platform rocks of central New York appears to have occurred along ancient crustal structures that were reactivated by the far field stresses related to the opening of the North Atlantic Ocean.

  7. Extrusion Processing of Cactus Pear

    Directory of Open Access Journals (Sweden)

    Preetam Sarkar

    2011-04-01

    Full Text Available Whole fruit utilization using extrusion technology has received limited attention in the food processing industry. The objective of this study was to investigate the utilization of prickly pear fruit solids in extruded food products. Peeled prickly pear fruits were ground to form a paste. This paste was strained to remove the seeds and then mixed with rice flour in three different solid ratios. The three blends were dried to a moisture level of 13% (w/w basis and ground to form fine flour. These feed mixes were extruded in a twin screw extruder (Clextral EV-25 at a feed rate of 15 kg/h, feed moisture content of 13% (w/w, screw speed of 400 rpm and L/D ratio of 40:1. The temperature profile from feed to die end was maintained as: 25, 30, 40, 50, 60, 70, 80, 100, 120, 140ºC. The extruded products were analyzed for physical and textural properties. Apparent density and breaking strength of the cactus pear extrudates increased from 116.07 to 229.66 kg/m3 and 58.5 to 178.63 kPa, respectively with increase in fruit solid level. However, true density, porosity and radial expansion ratio decreased from 837.89 to 775.84 kg/m3, 86.12 to 70.34% and 12.37 to 6.6, respectively with increase in fruit solid level. This study demonstrated the potential of extrusion processing to utilize peeled cactus pear fruits for production of expanded food products.

  8. Hot extrusion of Be–Ti powder

    Energy Technology Data Exchange (ETDEWEB)

    Kurinskiy, P., E-mail: petr.kurinskiy@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials—Applied Materials Physics (IAM—AWP), PO Box 3640, 76021 Karlsruhe (Germany); Leiste, H. [Karlsruhe Institute of Technology, Institute for Applied Materials—Applied Materials Physics (IAM—AWP), PO Box 3640, 76021 Karlsruhe (Germany); Goraieb, A.A. [Karlsruhe Beryllium Handling Facility (KBHF GmbH), Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Mueller, S. [Extrusion Research and Development Center, TU Berlin, Sekr. TIB 4/1-2, Gustav-Meyer-Allee 25, 13355 Berlin (Germany)

    2015-10-15

    Highlights: • Extrusion in double-walled containment of Be–Ti blended powder was investigated. • Fabrication of Be–Ti rods by extrusion at 700 °C showed more satisfactory results compared to an extrusion at 900 °C. • Factors which influence homogeneous and stable metal flow during extrusion are discussed. - Abstract: Be–30.8 wt.%Ti powder mixture was extruded in copper and steel containers at 700 and 900 °C, respectively. In both cases, achieved extrusion ratio was 7:1. Investigations of microstructure of manufactured Be–Ti rods revealed that processing temperature has a great influence on the metal flow during the extrusion as well as formation of beryllide phases. The results obtained by X-ray diffraction (XRD) analysis proved that brittle intermetallic phases were formed by processing at 900 °C; while no evidence of reaction between beryllium and titanium was detected after extrusion at 700 °C. Additionally, high-temperature annealing tests of produced Be–Ti samples were performed in order to study the evolution of the phase composition after the heat treatment. The effects of different mechanical properties of core materials (beryllium and titanium) and containers on uniform deformation are discussed in this work.

  9. Extrusion of ECC: Recent Developments and Applications

    DEFF Research Database (Denmark)

    Stang, Henrik; Fredslund-Hansen, Helge; Puclin, Tony;

    2008-01-01

    process. Extrusion of cementitious (fiber reinforced) materials has proven particularly difficult due to the high inter-particle friction combined with the disastrous effect of static zones in the flow pattern, and to the ease of phase migration or separation. In order to deal with these conflicting...... demands on the rheological properties of cementitious particulate materials, various methods have been suggested to dewater the particle suspension during extrusion, however practical extrusion of thin-walled cementitious large-scale elements has not been possible until the discovery of the “dewatering...

  10. A finite element model of ultrasonic extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, M [Department of Mechanical Engineering, University of Glasgow, G12 8QQ (United Kingdom); Daud, Y, E-mail: m.lucas@mech.gla.ac.u [College of Science and Technology, UTM City Campus, Kuala Lumpur (Malaysia)

    2009-08-01

    Since the 1950's researchers have carried out investigations into the effects of applying ultrasonic excitation to metals undergoing elastic and plastic deformation. Experiments have been conducted where ultrasonic excitation is superimposed in complex metalworking operations such as wire drawing and extrusion, to identify the benefits of ultrasonic vibrations. This study presents a finite element analysis of ultrasonic excitation applied to the extrusion of a cylindrical aluminium bar. The effects of friction on the extrusion load are reported for the two excitation configurations of radially and axially applied ultrasonic vibrations and the results are compared with experimental data reported in the literature.

  11. A finite element model of ultrasonic extrusion

    Science.gov (United States)

    Lucas, M.; Daud, Y.

    2009-08-01

    Since the 1950's researchers have carried out investigations into the effects of applying ultrasonic excitation to metals undergoing elastic and plastic deformation. Experiments have been conducted where ultrasonic excitation is superimposed in complex metalworking operations such as wire drawing and extrusion, to identify the benefits of ultrasonic vibrations. This study presents a finite element analysis of ultrasonic excitation applied to the extrusion of a cylindrical aluminium bar. The effects of friction on the extrusion load are reported for the two excitation configurations of radially and axially applied ultrasonic vibrations and the results are compared with experimental data reported in the literature.

  12. An ion microprobe U-Th- Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland

    Directory of Open Access Journals (Sweden)

    Petri Peltonen

    2001-01-01

    Full Text Available Eleven relatively large (diameter 1–2 mm zircon grains extracted from the Lahtojoki kimberlite pipe (Eastern Finland Kimberlite Province have been analysed by the ion microprobe NORDSIM for their U- and Pb- isotopic composition. The 207Pb/206Pb ages fall into two concordant age groups: 2.7 Ga and 1.8 Ga. Discordant ages between these two groups are believed to result from partial resetting of Archaean grains in the 1.8 Ga thermal event. Since other datingmethods imply that kimberlites emplaced c. 0.6 Ga ago it is clear that the analysed zircons are xenocrysts inherited from older sources and do not provide the age of the kimberlite magmatism. Their unusual size and morphology, together with very low U- and Pb-concentrations, suggest, however, that these zircon grains are not derived from typical Archaean gneisses. More likely, they originate from lower crustal mafic pegmatites and from hydrous coarse-grained veins within the uppermost lithospheric mantle. The predominance of 1.8 Ga old xenocrystic grains, together with the recovery of mafic granulite xenoliths of similar age in the kimberlites (Hölttä et al. 2000, emphasises the importance of post-collisional lower crustal growth and reworking in central Fennoscandia.

  13. Lubrication in Hot Tube Extrusion of Superalloys and Ti Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Tubular products made of superalloys and titanium alloys usually work in high temperature environment and applied heavy loading. Hot extrusion is the best technology to form tubular billets with fine microstructures and good mechanical properties. Lubrication is one of the key techniques in hot extrusion, glass lubricants are most suitable for hot extrusion. Lubrication technique in hot extrusion is dealt with in this paper, the lubrication principle of hot tube extrusion is presented. Experiments of glass lubricated backward tube extrusion of titanium alloys and forward tube extrusion of superalloys are also discussed.

  14. Co-extrusion of piezoelectric ceramic fibres

    OpenAIRE

    Ismael Michen, Marina

    2011-01-01

    The present work successfully developed a methodology for fabricating lead zirconate titanate [PZT] thin solid- and hollow-fibres by the thermoplastic co-extrusion process. The whole process chain, that includes: a) compounding, involving the mixing of ceramic powder with a thermoplastic binder, b) rheological characterizations, c) preform composite fabrication followed by co-extrusion, d) debinding and, finally, e) sintering of the body to near full density, is systematical...

  15. Evaluation of Extrusion Technique for Nanosizing Liposomes

    Directory of Open Access Journals (Sweden)

    Sandy Gim Ming Ong

    2016-12-01

    Full Text Available The aim of the present study was to study the efficiency of different techniques used for nanosizing liposomes. Further, the aim was also to evaluate the effect of process parameters of extrusion techniques used for nanosizing liposomes on the size and size distribution of the resultant liposomes. To compare the efficiency of different nanosizing techniques, the following techniques were used to nanosize the liposomes: extrusion, ultrasonication, freeze-thaw sonication (FTS, sonication and homogenization. The extrusion technique was found to be the most efficient, followed by FTS, ultrasonication, sonication and homogenization. The extruder used in the present study was fabricated using readily available and relatively inexpensive apparatus. Process parameters were varied in extrusion technique to study their effect on the size and size distribution of extruded liposomes. The results obtained indicated that increase in the flow rate of the extrusion process decreased the size of extruded liposomes however the size homogeneity was negatively impacted. Furthermore, the liposome size and distribution was found to decline with decreasing membrane pore size. It was found that by extruding through a filter with a pore size of 0.2 µm and above, the liposomes produced were smaller than the pore size, whereas, when they were extruded through a filter with a pore size of less than 0.2 µm the resultant liposomes were slightly bigger than the nominal pore size. Besides that, increment of extrusion temperature above transition temperature of the pro-liposome had no effect on the size and size distribution of the extruded liposomes. In conclusion, the extrusion technique was reproducible and effective among all the methods evaluated. Furthermore, processing parameters used in extrusion technique would affect the size and size distribution of liposomes. Therefore, the process parameters need to be optimized to obtain a desirable size range and homogeneity

  16. Assortment of Deep Mantle Fluids and Their Products in Kimberlites from China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Lei; HAO Jinhua; DING Yifei; LIU Yulong

    2004-01-01

    Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid-transmitted minerals with an oxygen-free feature, the deep fluid metasomatized-minerals characterized by enrichment in TiO2, K2O, BaO, REE and Fe3+, and the deep fluidreformed minerals. The three types show a successive descent in fluid origin depth and metasomatism strength, and they have brought forth a series of corresponding metasomatic products.

  17. Garnet peridotite xenoliths in a Montana, U.S.A., kimberlite

    Science.gov (United States)

    Carter, Hearn B.; Boyd, F.R.

    1975-01-01

    Within a swarm of late middle Eocene subsilicic-alkalic diatremes, one diatreme 270 by 370 m and an associated dike contain common xenoliths of granulite and rare xenoliths of spinel peridotite and garnet peridotite. Six garnet lherzolite xenoliths have been found and these show a range of textures. Four are granular, and two are intensely sheared. Phlogopite is absent from the intensely sheared xenoliths and is thought to be primary in part in the granular xenoliths. Estimated temperatures and depths of equilibration of xenolith pyroxenes range from 920??C, 106 km (32 kbar) to 1315??C, 148 km (47 kbar). The xenoliths show increasing amounts of deformation with greater inferred depths of origin. The temperature-depth points suggest a segment of an Eocene geotherm for Montana which is similar in slope to the steep portion of the pyroxene-determined Lesotho geotherm (Boyd and Nixon, this volume) and is considerably steeper than typical calculated shield and continental geotherms at present. The steep trend could be a result of plate-tectonic shearing and magma ascension within an Eocene low-velocity zone. Preservation of intensely sheared textures requires rapid transport of material from about 150 km depth during active deformation of relatively dry rock. The occurrence of monticellite peridotite in this kimberlite diatreme suggests that magmas which crystallized to monticellite peridotite at relatively shallow depth could be one of the primitive types of kimberlite magma. ?? 1975.

  18. Peridotite xenoliths from the Jagersfontein kimberlite pipe: I. Primary and primary-metasomatic mineralogy

    Energy Technology Data Exchange (ETDEWEB)

    Harte, B. (Univ. of Edinburgh (England)); Gurney, J.J. (Univ. of Cape Town (South Africa)); Winterburn, P.A. (Univ. of Edinburgh (England) Isotope Geochemistry Facility, Pretoria (South Africa))

    1990-02-01

    The geochemistry and textures of peridotite xenoliths from the Jagersfontein kimberlite pipe are reported. The xenoliths have a primary mineralogy of olivine {plus minus} orthopyroxene {plus minus} clinopyroxene {plus minus} garnet {plus minus} spinel. They are subdivided into coarse and deformed xenoliths corresponding to high- and low-temperature estimates, respectively. Coarse-grained xenoliths are further subdivided into low- and medium-temperature groups. Mineral chemistry of these two groups is distinct, e.g., clinopyroxene 100 Al/(Al + Cr) 24 to 60 and 60 to 70 in the medium- and low-temperature groups, respectively. Low-temperature xenoliths have undergone exsolution of pyroxene, spinel, and garnet in their pyroxenes. Primary modal metasomatism has occurred in the coarse xenoliths with the replacement of orthopyroxene by edenitic amphibole in the low-temperature xenoliths and of clinopyroxene by low-Ti phlogopite in the medium-temperature xenoliths. The amphibole stability limit confines it to shallower depths. Metasomatized xenoliths have been enriched in K, Na, Al, and Ca, and trace incompatible elements. Metasomatism is considered to have occurred at round 1 Ga by the infiltration of, and reaction with, ascending H{sub 2}O-rich fluids with Sr and Nd isotopic characteristics similar to group II kimberlites. The widespread chemical equilibrium seen in metasomatized xenoliths suggests that the particularly distinctive features of the low-temperature Jagersfontein xenoliths, namely exsolution and very low equilibration temperatures, may also be a result of the primary metasomatism.

  19. Sm-Nd, K-Ar and petrologic study of some kimberlites from eastern United States and their implication for mantle evolution

    Science.gov (United States)

    Basu, A.R.; Rubury, E.; Mehnert, H.; Tatsumoto, M.

    1984-01-01

    We provide new data on Sm-Nd systematics, K-Ar dating and the major element chemistry of kimberlites from the eastern United States (mostly from central New York State) and their constituent mineral phases of olivine, clinopyroxene, garnet, phlogopite and perovskite. In addition, we report Nd-isotopes in a few kimberlites from South Africa, Lesotho and from the eastern part of China. The major element compositions of the New York dike rocks and of their constituent minerals including a xenolith of eclogite are comparable with those from the Kimberley area in South Africa. The K-Ar age of emplacement of the New York dikes is further established to be 143 Ma. We have analyzed the Nd-isotopic composition of the following kimberlites and related rocks: Nine kimberlite pipes from South Africa and Lesotho, two from southern India; one from the U.S.S.R., fifteen kimberlite pipes and related dike rocks from eastern and central U.S. and two pipes from the Shandong Province of eastern China. The age of emplacement of these kimberlites ranges from 1300 million years to 90 million years. The initial Nd-isotopic compositions of these kimberlitic rocks expressed as e{open}NdIwith respect to a chondritic bulk-earth growth-curve show a range between 0 and +4, with the majority of the kimberlites being in the range 0 to +2. This range is not matched by any other suite of mantle-derived igneous rocks. This result strengthens our earlier conclusion that kimberlitic liquids are derived from a relatively primeval and unique mantle reservoir with a nearly chondritic Sm/Nd ratio. ?? 1984 Springer-Verlag.

  20. Extrusion Upsetting Multiple Processing in Sandglass Die

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new method of getting ultrafine grain size has been investigated, which is called "Extrusion Upsetting Multiple Processing in Sandglass Die" or "Sandglass Extrusion" (SE). Since the shape of tested billet can remain unchanged after SE, the billet can be extruded repeatedly in order to get large plastic strain. The ultrafine grain size can be obtained in the billet material due to the large plastic strain and the dynamic recrystallization during SE. The experiments on SE of Zn-5%Al alloy have been done. The SE technology, microstructures, microhardness and superplasticity of tested material after SE have been studied. The experimental results show that the equal-axial ultrafine microstructures can be introduced to the bulk test material during sandglass extrusion. The high strain rate superplasticity can be realized.

  1. The MajuagaaA Kimberlite Dike, Maniitsoq Regio, West Greenland: Constraints on an Mg-rich Silicocarbonatitic Melt Composition from Groundmass Mineralogy and Bulk Compositions

    DEFF Research Database (Denmark)

    Nielsen, Troels F. D.; Sand, Karina Krarup

    2008-01-01

    as kimberlite, despite being carbonate-rich and the apparent absence of monticellite characteristic of many occurrences of bona fide hypabyssal kimberlite. Olivine megacrysts, macrocrysts and microcrysts are all xenocrystic, whereas microphenocrysts are xenocrystic microcrysts overgrown by equilibrium olivine....... Most olivine (max. 37 wt.%) is found to be xenocrystic on the basis of Ni mass balance. The average bulk composition of the melt involved in the dike compares well with Group-1 kimberlite. Corrected for xenocrystic olivine and ilmenite, the melt has the composition of a silicocarbonatite and compares...

  2. Study on Extrusion Technological Parametersof Brown Rice

    Institute of Scientific and Technical Information of China (English)

    ZhuYongyi; ZhouXianqing; LingLizhong

    2001-01-01

    Abstract: Extrusion is an efficient measure to improve the texture and physic-chemical properties of brown rice. The polynomial degree two model of extrusiontechnological parameters and gelatinized degree, water absorption index, water solubleindex and moisture content of extruded matter was obtained by methods of single factorand response surface methodology, R2=0.9649, 0.8745, 0.9079, 0.8677. The optimaltechnoiogica! parameters of brown rice extrusion were figured out as follows:moisturecontent of brown rice, 11.42%, speed of screw, 30rpm, feeding speed, and 20rpm.

  3. IMPORTANT DEGRADATIONS IN POLYETHYLENE TERAPHTALATE EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Şule ALTUN

    2003-01-01

    Full Text Available Polyethylene terephthalate (PET is one of the most used thermo-plastic polymers. The total consumption of PET has been about 30 million tons in the year 2000. Polyester fibers constitute about 60 % of total synthetic fibers consumption. During extrusion, PET polymer is faced to thermal, thermo-oxidative and hydrolytic degradation, which result in severe reduction in its molecular weight, thereby adversely affecting its subsequent melt processability. Therefore, it is essential to understand degradation processes of PET during melt extrusion.

  4. Elaboration de membranes pour piles a combustible par extrusion

    OpenAIRE

    Chabert, France

    2004-01-01

    The aim of these studies was to process membranes by extrusion to be used in fuel cells. The functional polymers used are generally processed by polluting techniques like casting-evaporation, which are not easily transposable on industrial scale. Extrusion is a widely used shaping operation in the polymer processing industry. However, extrusion had not been used until now for arylsulfonic ionic polymers. In order to avoid any risk of degradation of the polymer during extrusion, it was necessa...

  5. Effects of extrusion processing on nutrients in dry pet food

    NARCIS (Netherlands)

    Tran, Q.D.; Hendriks, W.H.; Poel, van der A.F.B.

    2008-01-01

    Extrusion cooking is commonly used to produce dry pet foods. As a process involving heat treatment, extrusion cooking can have both beneficial and detrimental effects on the nutritional quality of the product. Desirable effects of extrusion comprise increase in palatability, destruction of

  6. Extrusion instability in an aramid fibre spinning process

    NARCIS (Netherlands)

    Drost, S.

    2015-01-01

    The efficiency of polymer extrusion processes can be severely limited by the occurrence of viscoelastic extrusion instabilities. In a para-aramid fibre spinning process, for example, a μm-scale extrusion instability is responsible for the waste of tons of polymer per year. At present, a considerab

  7. Effects of extrusion conditions on the extrusion responses and the quality of brown rice pasta.

    Science.gov (United States)

    Wang, Li; Duan, Wei; Zhou, Sumei; Qian, Haifeng; Zhang, Hui; Qi, Xiguang

    2016-08-01

    This research investigated the effects of extrusion temperature and screw speed on the extrusion system parameters and the qualities of brown rice pasta. The die pressure and motor torque value reached a maximum at 90°C but decreased when the screw speed increased from 80 to 120rpm. The extrusion temperature and screw speed also significantly affected the cooking quality and textural properties of brown rice pasta. The pasta produced at an extrusion temperature of 120°C and screw speed of 120rpm had the best quality with a cooking loss, hardness and adhesiveness of 6.7%, 2387.2g and -7.0g⋅s, respectively, similar to those of pasta made from gluten-free flour. The results indicated that brown rice can be used to produce gluten-free pasta with improved nutrition.

  8. Physical and mathematical modelling of extrusion processes

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Gronostajski, Z.; Niechajowics, A.

    2000-01-01

    The main objective of the work is to study the extrusion process using physical modelling and to compare the findings of the study with finite element predictions. The possibilities and advantages of the simultaneous application of both of these methods for the analysis of metal forming processes...

  9. Hydrodynamic modelling of hydrostatic magnesium extrusion

    NARCIS (Netherlands)

    Moodij, E.; Rooij, de M.B.; Schipper, D.J.

    2006-01-01

    Wilson’s hydrodynamic model of the hydrostatic extrusion process is extended to meet the geometry found on residual billets. The transition from inlet to work zone of the process is not considered sharp as in the model of Wilson but as a rounded edge, modelled by a parabolic function. It is shown th

  10. Friction phenomena in hydrostatic extrusion of magnesium

    NARCIS (Netherlands)

    Moodij, Ellen

    2014-01-01

    When magnesium is hydrostatically extruded an inconsistent and sometimes bad surface quality is encountered. In hydrostatic extrusion the billet is surrounded by a lubricant, usually castor oil. The required pressure to deform the material is applied onto this lubricant and not directly to the bill

  11. Formation of Chromosomal Domains by Loop Extrusion

    Directory of Open Access Journals (Sweden)

    Geoffrey Fudenberg

    2016-05-01

    Full Text Available Topologically associating domains (TADs are fundamental structural and functional building blocks of human interphase chromosomes, yet the mechanisms of TAD formation remain unclear. Here, we propose that loop extrusion underlies TAD formation. In this process, cis-acting loop-extruding factors, likely cohesins, form progressively larger loops but stall at TAD boundaries due to interactions with boundary proteins, including CTCF. Using polymer simulations, we show that this model produces TADs and finer-scale features of Hi-C data. Each TAD emerges from multiple loops dynamically formed through extrusion, contrary to typical illustrations of single static loops. Loop extrusion both explains diverse experimental observations—including the preferential orientation of CTCF motifs, enrichments of architectural proteins at TAD boundaries, and boundary deletion experiments—and makes specific predictions for the depletion of CTCF versus cohesin. Finally, loop extrusion has potentially far-ranging consequences for processes such as enhancer-promoter interactions, orientation-specific chromosomal looping, and compaction of mitotic chromosomes.

  12. 75 FR 80527 - Aluminum Extrusions From China

    Science.gov (United States)

    2010-12-22

    ... Republic of China: Postponement of Final Determination of Sales at Less Than Fair Value, 75 FR 73041... Sales at Less Than Fair Value, and Preliminary Determination of Targeted Dumping, 75 FR 69403, November... Affirmative Countervailing Duty Determination, 75 FR 54302, September 7, 2010, and Aluminum Extrusions...

  13. Energy aspects in food extrusion-cooking

    NARCIS (Netherlands)

    Janssen, L.P.B.M.; Moscicki, L.; Mitrus, M.

    2002-01-01

    Theoretical and practical energy balance considerations in food extrusion-cooking are presented in the paper. Based on the literature review as well as on own measurement results, the baro-thermal treatment of different vegetable raw materials is discussed together with the engineering aspects of th

  14. Limits of Lubrication in Backward Can Extrusion

    DEFF Research Database (Denmark)

    Bennani, B; Bay, Niels

    1996-01-01

    The increasing demand in industry to produce cans at low reduction by the backward extrusion process involves better understanding of this process. To analyse the process, numerical simulations by the finite-element method and experimental simulations by physical modelling using wax as a model...

  15. Robo-Enabled Tumor Cell Extrusion.

    Science.gov (United States)

    Richardson, Helena E; Portela, Marta

    2016-12-19

    How aberrant cells are removed from a tissue to prevent tumor formation is a key question in cancer biology. Reporting in this issue of Developmental Cell, Vaughen and Igaki (2016) show that a pathway with an important role in neural guidance also directs extrusion of tumor cells from epithelial tissues.

  16. Root resorption after orthodontic intrusion and extrusion:.

    NARCIS (Netherlands)

    Han, G.; Huang, S.; Hoff, J.W. Von den; Zeng, X.; Kuijpers-Jagtman, A.M.

    2005-01-01

    The aim of this investigation was to compare root resorption in the same individual after application of continuous intrusive and extrusive forces. In nine patients (mean age 15.3 years), the maxillary first premolars were randomly intruded or extruded with a continuous force of 100 cN for eight wee

  17. Physical and mathematical modelling of extrusion processes

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Gronostajski, Z.; Niechajowics, A.

    2000-01-01

    The main objective of the work is to study the extrusion process using physical modelling and to compare the findings of the study with finite element predictions. The possibilities and advantages of the simultaneous application of both of these methods for the analysis of metal forming processes...

  18. Improved corn protein (zein) extrusion processing

    Science.gov (United States)

    Melt processing using a single and twin screw extruder has been carried out on zein where extrusion temperatures were varied between 100ºC and 300ºC. In addition, melt reprocessing (up to seven times) of zein was undertaken using a single screw extruder. Differential scanning calorimetry (DSC) and t...

  19. Reactive Extrusion of Zein with Glyoxal

    Science.gov (United States)

    Cross-linked zein has been produced using glyoxal as the cross-linking reagent via reactive extrusion for the first time in a twin screw extruder using dilute sodium hydroxide as catalyst. Tri(ethylene glycol) was used as a plasticizer for various items. The extrudate was then ground and processed...

  20. Origin of Ti-rich garnets in the groundmass of Wajrakarur field kimberlites, southern India: insights from EPMA and Raman spectroscopy

    Science.gov (United States)

    Dongre, Ashish N.; Viljoen, K. S.; Rao, N. V. Chalapathi; Gucsik, A.

    2016-04-01

    Although Ti-rich garnets are commonly encountered in the groundmass of many alkaline igneous rocks, they are comparatively rare in kimberlites. Here we report on the occurrence of Ti-rich garnets in the groundmass of the P-15 and KL-3 kimberlites from the diamondiferous Wajrakarur field in the Eastern Dharwar craton of southern India. These garnets contain considerable Ti (11.7-23.9 wt.% TiO2), Ca (31.3-35.8 wt.% CaO), Fe (6.8-15.5 wt.% FeOT) and Cr (0.04-9.7 wt.% Cr2O3), but have low Al (0.2-5.7 wt.% Al2O3). In the case of the P-15 kimberlite they display a range in compositions from andradite to schorlomite, with a low proportion of grossular (andradite(17.7-49.9)schorlomite(34.6-49.5)-grossular(3.7-22.8)-pyrope(1.9-10.4)). A few grains also contain significant chromium and represent a solid solution between schorlomite and uvarovite. The Ti-rich garnets in the KL-3 kimberlite, in contrast, are mostly schorlomitic (54.9-90.9 mol %) in composition. The Ti-rich garnets in the groundmass of these two kimberlites are intimately associated with chromian spinels, perhaps suggesting that the garnet formed through the replacement of spinel. From the textural evidence, it appears unlikely that the garnets could have originated through secondary alteration, but rather seem to have formed through a process in which early magmatic spinels have reacted with late circulating, residual fluids in the final stages of crystallization of the kimberlite magma. Raman spectroscopy provides evidence for low crystallinity in the spinels which is likely to be a result of their partial transformation into andradite during their reaction with a late-stage magmatic (kimberlitic) fluid. The close chemical association of these Ti-rich garnets in TiO2-FeO-CaO space with those reported from ultramafic lamprophyres (UML) is also consistent with results predicted by experimental studies, and possibly implies a genetic link between kimberlite and UML magmas. The occurrence of Ti-rich garnets of

  1. Helium isotopic variability within single diamonds from the Orapa kimberlite pipe

    Science.gov (United States)

    Kurz, Mark D.; Jenkins, William J.; Lott, Dempsey E., III; Gurney, John J.

    1987-01-01

    The possible relationships between diamond mineralogy and helium isotopes were investigated by measuring the distribution and isotopic composition of He in a suite of well-characterized one-carat diamonds from the Orapa kimberlite, Botswana. The results of crushing in vacuo experiments indicated that most of He was contained in the matrix, rather than in the inclusions of the diamonds. Step-heating of individual diamonds at 2000 C released He of He-3/He-4 ratios that differed by up to a factor of 100 among the two heating steps, revealing large isotopic variations within individual diamonds. It is suggested that this internal isotopic variability is the result of stepwise graphitization: the first heating step initiates graphitization which nucleates around defects in a diamond, and the second step graphitizes the relatively defect-free regions of the diamond. This explanation predicts that the highest He-3/He-4 ratios should be found in most perfect crystals.

  2. Rheological investigations of tailings of kimberlite ore dressing and numerical simulation of its behaviour in PLAXIS

    Science.gov (United States)

    Korshunov, A.; Nevzorov, A.

    2015-04-01

    The article presents the results of analysis of rheology properties of sandy-clay tailings (wastes) of kimberlite ore dressing of the diamond deposit (Russia, Arkhangelsk region). The coefficient of secondary compression as main parameter of soil's creep is defined by implementing standard one-dimensional consolidation test. The linear correlation between initial void ratio and coefficient of secondary compression of sandy-clay tailings were obtained. For numerical simulation of tailing's behaviour subject to its rheology properties in Soft Soil Creep (SSC) model (time independent behaviour) of PLAXIS software was used. According to laboratory tests calibration of SSC model was implemented. It allows predicting dam's safety and reliability for long-term outlook.

  3. Kimberlite-Clan-Rocks in India: Significance of new VGP, T, and GP Observations.

    Science.gov (United States)

    Haggerty, S. E.

    2005-05-01

    Although India is acknowledged for the first description of diamond some 2000 BCE, it should also rightfully be credited for the 17th C recognition that diamond is a product of volcanism. With this extraordinary background, it is surprising that the host rocks remain controversial, being neither archetypical kimberlites, nor classic lamproites. Lacking affinities to micro-diamond-bearing UHPT metamorphic rocks and being unequivocally volcanic, the term Kimberlite-Clan-Rock (KCR) is applied. Over 200 KCR pipes and dikes, many of which are richly mineralized, have recently been discovered in the Diamond Corridor (1000 x 200 km) of the Eastern Dharwar Craton, and in adjoining cratons to the N and NE. From 32 absolute age determinations on KCRs, the remaining intrusions, in comparable stratigraphic settings, are assumed to be 1.1 Ga, equivalent to the Argyle lamproite (Australia, highest diamond grade), and the Premier kimberlite (RSA, largest known diamond). India has the largest number of known Proterozoic KCR intrusions that over the centuries have produced a wealth of famous diamonds. The primary source of these extraordinary stones, however, remains unknown, possibly because the unusual host rocks defy conventional exploration protocols. Six new observations make the setting even more unusual: (1) Coeval, large scale magmatism in the Kalahari (>2 m sq km) and Laurentian (>300 k cub km) Cratons at 1085-1112 Ma, during assembly of Rodinia, confirms the relation between and among KCR volcanism, LIPs, and supercontinents; Proterozoic Rodinia, into which the India KCRs, Argyle and Premier were intruded, was constructive, whereas the other, globally-wide, diamond-intrusive event, that occurred during the Mesozoic (80-120 Ma), was related to the breakup of Pangea and the dispersion of Gondwana; both events occurred during long period geomagnetic chrons implying a core relation, and superplume activity from the CMB. (2)The transcontinental Mumbai-Chennai gravity lineament

  4. Noise-induced variability of volcanic extrusions

    Science.gov (United States)

    Alexandrov, D. V.; Bashkirtseva, I. A.; Ryashko, L. B.

    2016-11-01

    Motivated by important physical applications, we study a non-linear dynamics of volcanic extrusions on the basis of a simple pressure-mass flow model. We demonstrate that the deterministic phase portrait represents either the bulbous-type curves or closed paths stretched to their left depending on the initial conditions. The period of phase trajectories therewith increases when the pressure drop between the conduit top and bottom compensates the lava column pressure in it. Stochastic forcing changes the system dynamics drastically. We show that a repetitive scenario of volcanic behaviour with intermittency of stochastic oscillations of different extrusion amplitudes and frequencies appears in the presence of noises. As this takes place, the mean values of interspike intervals characterizing the system periodicity have a tendency to grow with increasing the noise intensity. The probability distribution functions confirming this dynamic behaviour are constructed.

  5. A process planning system for cold extrusion

    Directory of Open Access Journals (Sweden)

    SANTOSH KUMAR,

    2010-12-01

    Full Text Available A Process Planning system ProEx-Cold is developed for extrusion shapes to eliminate the tedious and expensive procedure of trial and correction of a proper die and the process. The system has three modules as: feature recognition, upper bound analysis and 3D graphics generation & display using OpenGL application engine. The input parameters to the proposed CAPP system includes: die type, billet TYPE & material, geometrical details of the product, ram speed,reduction, friction condition and billet condition etc. to influence parameters like production rate, extrusion ram pressure etc. C-programming, OpenGL graphics and Visual C++ editor has been used to implement ProEx-Cold.

  6. Equal Channel Angular Extrusion of AA 6063 Using Conventional Direct Extrusion Press

    Science.gov (United States)

    Liu, Cheng-Hsien; Lin, Hsin-Chih

    2015-11-01

    In the present work, an extrusion-equal channel angular extrusion (Ex-ECAE) process composed of two processes, extrusion and ECAE, is developed. The Ex-ECAE die contains three segments and is used directly in the conventional direct extrusion press to refine the microstructure, specifically the coarse grain layer (CGL) on the surface of the extrudate. The first segment in the die is designed to perform the normal extrusion process and the second and third segments to perform the process of ECAE. The study reveals that the CGL can be eliminated (refined) completely at the macroscale. At the microscale, the original grain is subdivided into subgrain, which contains many smaller cells. The results can be explained by the grain subdivision mechanism. The textures of the Ex-ECAE sample at various segments are measured using EBSD (Electron Backscatter Diffraction). The results reveal that the first segment of the Ex-ECAE sample has a perfect fiber texture which consists of a mixture of strong and weak fiber components. The texture of the second segment is a mixture of strong (1 1 0) [1 -2 1] and weak (0 1 1) [2 -1 0] fiber components. However, the main component of the second segment is a typical texture of the "alloy" or "brass" type. Finally, the texture of the extrudate (the third segment) is reversed to an incomplete fiber texture which consists of strong (0 0 1) [-1 -1 0] and weak (1 1 1) [1 -1 0].

  7. The extrusion properties of potato granules

    OpenAIRE

    Kooi, Eng Teong

    1982-01-01

    Potato granules from different sources were found, on extrusion, to produce potato snacks of variable quality. In some instances strip formation was unsatisfactory, in other instances blistering of the snack occurred on frying. In total, about 20-25 batches of potato granules were examined and classified in relation to these two phenomena. The amylose/amylopectin ratios of these samples of potato granules were determined by the semi-micro potentiometric iodine titration technique, but it was ...

  8. Thermal Stabilization study of polyacrylonitrile fiber obtained by extrusion

    Directory of Open Access Journals (Sweden)

    Robson Fleming Ribeiro

    2015-12-01

    Full Text Available A low cost and environmental friendly extrusion process of the Polyacrylonitrile (PAN polymer was viabilized by using the 1,2,3-propanetriol (glycerol as a plasticizer. The characterization of the fibers obtained by this process was the object of study in the present work. The PAN fibers were heat treated in the range of 200 °C to 300 °C, which is the temperature range related to the stabilization/oxidation step. This is a limiting phase during the carbon fiber processing. The characterization of the fibers was made using infrared spectroscopy, thermal analysis and microscopy. TGA revealed that the degradation of the extruded PAN co-VA fibers between 250 °C and 350 °C, corresponded to a 9% weight loss to samples analyzed under oxidizing atmosphere and 18% when the samples were analyzed under inert atmosphere. DSC showed that the exothermic reactions on the extruded PAN co-VA fibers under oxidizing synthetic air was broader and the cyclization started at a lower temperature compared under inert atmosphere. Furthermore, FT-IR analysis correlated with thermal anlysis showed that the stabilization/oxidation process of the extruded PAN fiber were coherent with other works that used PAN fibers obtained by other spinning processes.

  9. Dynamic-tensile-extrusion response of fluoropolymers

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Eric N [Los Alamos National Laboratory; Trujillo, Carl P [Los Alamos National Laboratory; Gray, George T [Los Alamos National Laboratory

    2009-01-01

    The current work applies the recently developed Dynamic-Tensile-Extrusion (Dyn-Ten-Ext) technique to polytetrafluoroethylene (PTFE) and polychlorotrifluoroethylene (PCTFE). Similar to the Taylor Impact Rod, Dynamic-Tensile-Extrusion is a strongly integrated test, probing a wide range of strain rates and stress states. However, the stress state is primarily tensile enabling investigation of dynamic tensile failure modes. Here we investigate the influence of this propensity to neck or not between PCTFE and PTFE on their response under dynamic tensile extrusion loading. The results of the Dyn-Ten-Ext technique are compared with two classic techniques. Both polymers have been investigated using Tensile Split Hopkinson Pressure Bar. The quasistatic and dynamic responses of both fluoro-polymers have been extensively characterized. The two polymers exhibit significantly different failure behavior under tensile loading at moderate strain rates. Polytetrafluoroethylene resists formation of a neck and exhibits significant strain hardening. Independent of temperature or strain rate, PTFE sustains true strains to failure of approximately 1.5. Polychlorotrifluoroethylene, on the other hand, consistently necks at true strains of approximately 0.05.

  10. Stable isotope paleoclimatology of the earliest Eocene using kimberlite-hosted mummified wood from the Canadian Subarctic

    Directory of Open Access Journals (Sweden)

    B. A. Hook

    2014-11-01

    Full Text Available The recent discovery of well-preserved mummified wood buried within a subarctic kimberlite diamond mine prompted a paleoclimatic study of the early Eocene "hothouse" (ca. 53.3 Ma. At the time of kimberlite eruption, the Subarctic and Artic were warm and humid producing a temperate rainforest biome well north of the Arctic Circle. Previous studies have estimated mean annual temperatures in this region were 4–20 °C in the early Eocene, using a variety of proxies including leaf margin analysis, and stable isotopes (δ18O of fossil cellulose. Here, we examine stable isotopes of tree-ring cellulose at subannual to annual scale resolution, using the oldest viable cellulose found to date. We use mechanistic models and transfer functions to estimate earliest Eocene temperatures using mummified cellulose, which was well preserved in the kimberlite. Multiple samples of Piceoxylon wood within the kimberlite were crossdated by tree-ring width. Multiple proxies are used in combination to tease apart likely environmental factors influencing the tree physiology and growth in the unique extinct ecosystem of the Polar rainforest. Calculations of interannual variation in temperature over a multidecadal time-slice in the early Eocene are presented, with a mean temperature estimate of 11.4 °C (1σ = 1.8 °C based on δ18O. Dual-isotope spectral analysis suggests that multidecadal climate cycles similar to the modern Pacific Decadal Oscillation likely drove temperature and cloudiness trends on 20–30 year timescales.

  11. Archean Lithosphere Beneath Arctic Canada: Lu-Hf Isotope Systematics for Kimberlite-Hosted Garnet-Peridotites From Somerset Island

    Science.gov (United States)

    Schmidberger, S. S.; Simonetti, A.; Francis, D.; Gariepy, C.

    2001-05-01

    Knowledge of the age of lithospheric mantle underlying the continents provides valuable constraints for the timing of formation and stabilization of Archean cratons. This study reports Lu-Hf isotopic data for garnet-peridotites, and their constituent garnets, from the Nikos kimberlite (100 Ma) on Somerset Island in the Canadian Arctic obtained using a Micromass IsoProbe multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) at GEOTOP-UQAM. The low temperature peridotites (1100 C; 160-190 km) and their 176Hf/177Hf(0.1Ga) isotopic compositions (0.28265-0.28333; \\epsilonHf(0.1Ga)=-2 to +22) are less radiogenic than those of the shallow xenoliths. A Lu-Hf isochron for six peridotites yields a mid Archean age of 3.4\\pm0.3 Ga and an initial 176Hf/177Hf ratio of 0.28101\\pm24. The remaining peridotites (n=9), in contrast, are characterized by extremely high (+35) initial \\epsilonHf(3.4Ga) values, which correlate negatively with their 176Lu/177Hf ratios, suggesting addition of Hf as a result of metasomatic interaction with the host kimberlite. The garnets from the low temperature (3.4 Ga old) peridotites are characterized by high 176Lu/177Hf ratios and define an errorchron age of 1.4\\pm0.2 Ga, which may reflect re-equilibration of Hf during kimberlite magmatism.

  12. A conceptual model for kimberlite emplacement by solitary interfacial mega-waves on the core mantle boundary

    Science.gov (United States)

    Sim, B. L.; Agterberg, F. P.

    2006-07-01

    If convection in the Earth's liquid outer core is disrupted, degrades to turbulence and begins to behave in a chaotic manner, it will destabilize the Earth's magnetic field and provide the seeds for kimberlite melts via turbulent jets of silicate rich core material which invade the lower mantle. These (proto-) melts may then be captured by extreme amplitude solitary nonlinear waves generated through interaction of the outer core surface with the base of the mantle. A pressure differential behind the wave front then provides a mechanism for the captured melt to ascend to the upper mantle and crust so quickly that emplacement may indirectly promote a type of impact fracture cone within the relatively brittle crust. These waves are very rare but of finite probability. The assumption of turbulence transmission between layers is justified using a simple three-layer liquid model. The core derived melts eventually become frozen in place as localised topographic highs in the Mohorovicic discontinuity (Moho), or as deep rooted intrusive events. The intrusion's final composition is a function of melt contamination by two separate sources: the core contaminated mantle base and subducted Archean crust. The mega-wave hypothesis offers a plausible vehicle for early stage emplacement of kimberlite pipes and explains the age association of diamondiferous kimberlites with magnetic reversals and tectonic plate rearrangements.

  13. Peculiarities of mantle lithosphere beneath the large kimberlite pipes in different regions for Siberian craton

    Science.gov (United States)

    Ashchepkov, Igor; Logvinova, Alla; Ntaflos, Theodoros; Vladykin, Nikolai; Spetsius, Zdislav; Kostrovitsky, Sergey; Stegnitsky, Yuri; Prokopyev, Sergey

    2016-04-01

    Comparison of the structure of the mantle columns and mineralogy of the large kimberlite pipes in Yakutia from the different regions, kimberlite fields and mantle terranes in Yakutia allowed several assumptions. 1. The large kimberlite pipes possibly trace the ancient magma feeders occurred in the time of the continent growth. Commonly kimberlites and large pipes are tracing the deep faults and lineaments tracing the ancient sutures, rift zones, trans -lithospheric faults and other permeable structures, which may be parallel to the ancient continental margins. Large pipes locate at the periodic distance like volcanoes in arc settings tracing the "volcanic fronts". 2. Large pipes commonly contain the higher amounts of the sub-calcic garnets representing the dunitic associations (Stachel et al., 2008). In ophiolites dunites veins are representing the channels for the melt transfer (Kelemen et al., 2002). It is likely that ancient large magmatic arc system could have also deep seated roots represented by the (sub calcic) garnet - bearing dunitic systems. 3. Many large pipes including Udachnaya (Pokhilenko et al., 1999) and Mir (Roden et al., 2006) contain in mantle roots high amount of various pyroxenites. The most ancient pyroxenites are supplementary to the dunitic associations. But mostly they represent the materials from the re-melted eclogites and partial and hybrid melts (plume and subduction -related). They are concentrating in the traps in the lithosphere base, in the middle part of mantle section and in the basaltic trap 2.0-3.0 GPa. Pyroxenites in the lithosphere base in some cases are vary abundant but mostly they are protokimberlitic cumulates from of the latest stages of plume activity. Products of the melts crystallization from the earlier stages represent easy melting material at the lithosphere base could be the traps for the later plume melts. 5. Large pipes as a rule reveal contrast layering which is favorite for the capturing of the material from

  14. Heat Treated AZ61 Magnesium Alloy Obtained by Direct Extrusion and Continuous Rotary Extrusion Process

    Directory of Open Access Journals (Sweden)

    Bigaj M.

    2016-03-01

    Full Text Available The results of studies carried out on the heat treated AZ61 magnesium alloy extruded by two methods, i.e. direct extrusion and continuous rotary extrusion, were presented. As part of the work, parameters of the T6 heat treatment were proposed and aging curves were plotted. The solution heat treatment process was accompanied by the grain growth. During artificial aging, due to the decomposition of solid solution, the β-Mg17Al12 phase was precipitated from the supersaturated α solution. It precipitated in a coagulated form at the grain boundaries and in the form of fine-dispersed plates arranged in a preferred direction relative to the grain orientation. Rods obtained by continuous rotary extrusion, unlike those made by the direct process, exhibited a low degree of texturing and lack of anisotropic properties.

  15. Zr Extrusion – Direct Input for Models & Validation

    Energy Technology Data Exchange (ETDEWEB)

    Cerreta, Ellen Kathleen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-07

    As we examine differences in the high strain rate, high strain tensile response of high purity, highly textured Zr as a function of loading direction, temperature and extrusion velocity with primarily post mortem characterization techniques, we have also developed a technique for characterizing the in-situ extrusion process. This particular measurement is useful for partitioning energy of the system during the extrusion process: friction, kinetic energy, and temperature

  16. Hydrodynamic Analysis to Process of Hydrostatic Extrusion for Tungsten Alloy

    Institute of Scientific and Technical Information of China (English)

    Fuchi WANG; Zhaohui ZHANG; Shukui LI

    2001-01-01

    The hydrodynamic analysis to the process of the hydrostatic extrusion for tungsten alloy is carried through the hydrodynamic lubrication theory and Reynolds equation in this paper. The critical velocity equation when the hydrodynamic lubrication conditions appear between the surfaces of the work- piece and the die is obtained, and the relationship between the critical velocity and the extrusion parameters is discussed, which build the theoretical bases to the application of the hydrostatic extrusion for tungsten alloy.

  17. Intrusion and extrusion of water in hydrophobic mesopores

    OpenAIRE

    Barrat, Jean-Louis; Lefevre, Benoit; Bocquet, Lyderic; Saugey, Anthony; Vigier, Gérard; Gobin, Pierre-François; Charlaix, Elisabeth

    2003-01-01

    We present experimental and theoretical results on intrusion-extrusion cycles of water in hydrophobic mesoporous materials, characterized by independent cylindrical pores. The intrusion, which takes place above the bulk saturation pressure, can be well described using a macroscopic capillary model. Once the material is saturated with water, extrusion takes place upon reduction of the externally applied pressure; Our results for the extrusion pressure can only be understood by assuming that th...

  18. Syngenetic inclusions of yimengite in diamond from Sese kimberlite (Zimbabwe) — evidence for metasomatic conditions of growth

    Science.gov (United States)

    Bulanova, G. P.; Muchemwa, E.; Pearson, D. G.; Griffin, B. J.; Kelley, S. P.; Klemme, S.; Smith, C. B.

    2004-09-01

    Syngenetic inclusions of yimengite K (Cr, Ti, Mg, Fe, Al) 12O 19, a potassium member of the magnetoplumbite mineral group, have been recorded in an octahedral macrodiamond from the Sese kimberlite (50 km south of Masvingo, Zimbabwe). One yimengite inclusion carries lamellae of chromite suggesting peridotitic diamond paragenesis. The diamond and inclusions were studied in situ in a plate polished parallel to (011). Cathodoluminescence (CL) imaging has shown blue colour and octahedral zonation of the diamond, lack of cracks and the location of five yimengites in different growth zones. Nitrogen (N) contents (at. ppm) in the diamond determined by Fourier transform infrared spectroscopy (FTIR) steadily decrease from 576 (core) to 146 (rim). N aggregation (%1aB) is correspondingly 40% in the core and 30% in the rim. Hydrogen (H) content is high in the core, moderate in the intermediate and very high in the rim zones. Four yimengites were dated using the laser 40Ar/ 39Ar method. Three inclusions yielded total gas ages that agree with, or are younger than, or within error of, the Sese kimberlite eruption age (538±11 Ma) but may be compromised by gas loss. One inclusion, with the highest tapped interface gas yield, gave a total gas age of 892±21 Ma that is a likely minimum yimengite age. Time-T °C constraints from N aggregation systematics give a range of possible ages from kimberlite eruption date back to Archean and do not resolve the variable results of the 40Ar/ 39Ar dating. Compared with the published chemistry of yimengite from kimberlites, inclusions from the Sese diamond contain higher Al, Mg, and Sr and have lower concentration of Fe 3+. The chondrite-normalised REE pattern of the yimengite shows enrichment in LREE and depletion in HREE, but LREE/HREE fractionations are lower than for lindsleyite-mathiasite series mantle titanates and rather similar to the REE concentrations in kimberlite and lamproite rocks. It is suggested that Sese yimengite formed in the

  19. Continuous extrusion and rolling forming of copper strips

    Directory of Open Access Journals (Sweden)

    Yun Xinbing

    2016-01-01

    Full Text Available Continuous extrusion and rolling technology was proposed as a new strip production technology. It conducts a hot rolling process using waste heat after continuous extrusion. The continuous extrusion and rolling forming was simulated with DEFORM-3DT. Influences of extrusion wheel velocity and rolling reduction on the continuous extrusion and rolling forming were analyzed. It was shown that as extrusion wheel velocity increases, torque of extrusion wheel, chamber force and rolling force, will drop; temperature of the billet in the area of abutment which is highest will increase. As the rolling reduction is increased, torque of the extrusion wheel and force acting on the chamber decrease, while torque and force of the rolls increase. The experimental results showed that a homogeneously distributed and equiaxed grains microstructure can be formed in copper strip billets with an average grain size of about 80 μm, after continuous extrusion. Grains of the copper strips are stretched clearly, during rolling, along the rolling direction, to form a stable orientation. Nevertheless, the grain boundaries are still relatively clear to see.

  20. Conservation of extrusion as an exit mechanism for Chlamydia.

    Science.gov (United States)

    Zuck, Meghan; Sherrid, Ashley; Suchland, Robert; Ellis, Tisha; Hybiske, Kevin

    2016-10-01

    Chlamydiae exit via membrane-encased extrusion or through lysis of the host cell. Extrusions are novel, pathogen-containing structures that confer infectious advantages to Chlamydia, and are hypothesized to promote cell-to-cell spread, dissemination to distant tissues and facilitate immune evasion. The extrusion phenomenon has been characterized for several Chlamydia trachomatis serovars, but a thorough investigation of extrusion for additional clinically relevant C. trachomatis strains and Chlamydia species has yet to be performed. The key parameters investigated in this study were: (i) the conservation of extrusion across the Chlamydia genus, (ii) the functional requirement for candidate Chlamydia genes in extrusion formation i.e. IncA and CT228 and (iii) extrusion-mediated uptake, and consequent survival of Chlamydia inside macrophages. Inclusion morphology was characterized by live fluorescence microscopy, using an inverted GFP strategy, at early and mid-stages of infection. Enriched extrusions were used to infect bone marrow-derived macrophages, and bacterial viability was measured following macrophage engulfment. Our results demonstrate that extrusion is highly conserved across chlamydiae, including ocular, STD and LGV biovars and divergent Chlamydia species. Consequently, this exit mechanism for Chlamydia may fulfill common advantages important for pathogenesis.

  1. MODERNIZATION OF TECHNOLOGICAL LINE FOR CELLULAR EXTRUSION PROCESS

    Directory of Open Access Journals (Sweden)

    Tomasz Garbacz

    2014-06-01

    As part of the modernization of the cellular extrusion technology the extrusion head was designed and made. During the designing and modeling of the head the Auto CAD programe was used. After the prototyping the extrusion head was tested. In the article specification of cellular extrusion process of thermoplastics was presented. In the research, the endothermal chemical blowing agents in amount 1,0% by mass were used. The quantity of used blowing agent has a direct influence on density and structure of the extruded product of modified polymers. However, these properties have further influence on porosity, impact strength, hardness, tensile strength and another.

  2. In situ U-Pb age determination and Nd isotopic analysis of perovskites from kimberlites in southern Africa and Somerset Island, Canada

    Science.gov (United States)

    Wu, Fu-Yuan; Yang, Yue-Heng; Mitchell, Roger H.; Li, Qiu-Li; Yang, Jin-Hui; Zhang, Yan-Bin

    2010-03-01

    Determination of the emplacement ages and initial isotopic composition of kimberlite by conventional isotopic methods using bulk rock samples is unreliable as these rocks usually contain diverse clasts of crustal- and mantle-derived materials and can be subject to post-intrusion sub-aerial alteration. In this study, 8 samples from 5 kimberlites in southern Africa and twelve samples from 7 kimberlites from Somerset Island, Canada have been selected for in situ perovskite U-Pb isotopic age determination and Nd isotopic analysis by laser ablation using thin sections and mineral separates. These fresh perovskites occur as primary groundmass minerals with grain-sizes of 10-100 μm. They were formed during the early stage of magmatic crystallization, and record data for the least contaminated or contamination-free kimberlitic magma. U-Pb isotopic data indicate that the majority of the southern Africa kimberlites investigated were emplaced during the Cretaceous with ages of 88 ± 3 to 97 ± 6 Ma, although one sample yielded an Early Paleozoic age of 515 ± 6 Ma. Twelve samples from Somerset Island yielded ages ranging from 93 ± 4 Ma to 108 ± 5 Ma and are contemporaneous with other Cretaceous kimberlite magmatism in central Canada (103-94 Ma). Although whole-rock compositions of the kimberlites from southern Africa have a large range of ɛNd( t) values (- 0.5 to + 5.1), the analysed perovskites show a more limited range of + 1.2 to + 3.1. Perovskites from Somerset Island have ɛNd( t) values of - 0.2 to + 1.4. These values are lower than that of depleted asthenospheric mantle, suggesting that kimberlites might be derived from the lower mantle. This study shows that in situ U-Pb and Nd isotopic analysis of perovskite by laser ablation is both rapid and economic, and serves as a powerful tool for the determination of the emplacement age and potential source of kimberlite magmas.

  3. Extrusão dos implantes em portadores de cavidade anoftálmica Anophthalmic cavity and implant extrusion

    Directory of Open Access Journals (Sweden)

    Silvana Artioli Schellini

    2007-10-01

    Full Text Available OBJETIVO: Avaliar as características dos portadores de cavidades anoftálmicas que desenvolveram extrusão do implante. MÉTODOS: Estudo retrospectivo, observacional, tendo sido avaliados 37 portadores de cavidade anoftálmica que tiveram extrusão do implante de cavidade, na Faculdade de Medicina de Botucatu-UNESP. RESULTADOS: As extrusões ocorreram em cavidades enucleadas ou evisceradas, a maioria delas submetidas a cirurgia em decorrência de phthisis bulbi ou trauma, em geral de 1 a 2 anos após a cirurgia inicial. A deiscência precedeu a extrusão em todos os casos, tendo a extrusão ocorrido com todos os tipos de implantes empregados. CONCLUSÃO: Após a colocação de implantes de cavidade podem ocorrer complicações. A deiscência e extrusão das esferas são possibilidades que podem requerer nova intervenção cirúrgica, para a qual o paciente e o oftalmologista devem estar preparados.PURPOSE: To evaluate the characteristics of patients with anophthalmic cavity who developed sphere extrusion. METHODS: A retrospective observational study was done evaluating 37 patients with anophthalmic cavity and sphere extrusion at the "Faculdade de Medicina de Botucatu-UNESP". RESULTS: Extrusion was observed in enucleated and eviscerated cavities. The majority of the patients had the eye removed because of phthisis bulbi or trauma and the extrusion happened 1 or 2 years after the surgery. Extrusion was preceded by conjunctival dehiscence and exposure of the sphere and occurred with all used implants. CONCLUSION: Complications after orbital implant placement are a possibility. Dehiscence and sphere extrusion may happen and another surgery would be necessary. The patient and the ophthalmologist have to be prepared for this.

  4. Extrusion cycles during dome-building eruptions

    Science.gov (United States)

    de' Michieli Vitturi, M.; Clarke, A. B.; Neri, A.; Voight, B.

    2013-06-01

    We identify and quantify controls on the timescales and magnitudes of cyclic (periodic) volcanic eruptions using the numerical model DOMEFLOW (de' Michieli Vitturi et al., 2010) which was developed by the authors for magma systems of intermediate composition. DOMEFLOW treats the magma mixture as a liquid continuum with dispersed gas bubbles and crystals in thermodynamic equilibrium with the melt and assumes a modified Poiseuille form of the viscous term for fully developed laminar flow in a conduit of cylindrical cross-section. During ascent, magma pressure decreases and water vapor exsolves and partially degasses from the melt as the melt simultaneously crystallizes, causing changes in mixture density and viscosity. Two mechanisms previously proposed to cause periodic eruption behavior have been implemented in the model and their corresponding timescales explored. The first applies a stick-slip model in which motion of a shallow solid plug is resisted by static/dynamic friction, as described in Iverson et al. (2006). For a constant magma supply rate at depth, this mechanism yields cyclic extrusion with timescales of seconds to tens of seconds with values generally depending on assumed friction coefficients. The second mechanism does not consider friction but treats the plug as a high-viscosity Newtonian fluid. During viscous resistance, pressure beneath the degassed plug can increase sufficiently to overcome dome overburden, plug weight, and viscous forces, and ultimately drive the plug from the conduit. In this second model cycle periods are on the order of hours, and decrease with increasing magma supply rate until a threshold is reached, at which point periodicity disappears and extrusion rate becomes steady (vanishingly short periods). Magma volatile content for fixed chamber pressure has little effect on cycle timescales, but increasing volatile content increases mass flow rate and cycle magnitude as defined by the difference between maximum and minimum

  5. Expansion of the whole wheat flour extrusion

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    2008-01-01

    A new model framework is proposed to describe the expansion of extrudates with extruder operating conditions based on dimensional analysis principle. The Buckingham pi dimensional analysis method is applied to form the basic structure of the model from extrusion process operational parameters. Us....... Using the Central Composite Design (CCD) method, whole wheat flour was processed in a twin-screw extruder with 16 trials. The proposed model can well correlate the expansion of the 16 trials using 3 regression parameters. The average deviation of the correlation is 5.9%....

  6. STRAIN ANALYSIS OF LATERAL EXTRUSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The strain distribution of equal-cross section lateral extrusion(ECSLE) has been simulated by finite element method. Considering the effect of friction and the width of sample, the simulation results are very close to the reality. The simulated results showed that, around the corner of die, the strain is distributed by sharp layers, and the gradient of the layers is very large, which means that the deformation is just plane shear deformation; the larger the width of sample or the smaller the friction, the more uniform the strain distribution is.

  7. Expansion of the whole wheat flour extrusion

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    2008-01-01

    A new model framework is proposed to describe the expansion of extrudates with extruder operating conditions based on dimensional analysis principle. The Buckingham pi dimensional analysis method is applied to form the basic structure of the model from extrusion process operational parameters....... Using the Central Composite Design (CCD) method, whole wheat flour was processed in a twin-screw extruder with 16 trials. The proposed model can well correlate the expansion of the 16 trials using 3 regression parameters. The average deviation of the correlation is 5.9%....

  8. Electroencephalograpic coherence

    Directory of Open Access Journals (Sweden)

    Simon Brežan

    2004-08-01

    Full Text Available Different brain areas process various aspects of information in parallel as well as segregated way. It is not known, how is this information integrated into a unitary percept or action. The binding problem is one of the key problems in understanding brain function. Synchronized oscillatory activity of neurons is one possible mechanism of the functional integration of different communicating brain areas. The binding has been well-studied in the visual system, but it could also serve as a mechanism in visuomotor integration or functional coupling present with other brain processes and behavioural modes (perception, complex motor behaviour, selective attention, learning, working memory, etc.. Interregional synchronization of the electroencephalographic (EEG signal can be determined by EEG coherence analysis. In the article we present a research example of coherence changes in a visuomotor task. During this task, coherence between visual and motor brain areas increased. This might reflect functional coupling between those areas, but it could also be influenced by other cognitive processes (e.g. selective attention. Coherence analysis is suitable for studying integrative brain function. Because it measures only one of the possible mechanisms of integration, it offers promise especially when combined with other electrophysiological and functional imaging methods.

  9. About Basic Epochs of Crust Formation and Kimberlite Magmatism in Connection with Diamond Prospecting Works

    Directory of Open Access Journals (Sweden)

    N. N. Zinchuk

    2014-06-01

    Full Text Available Results of comprehensive analysis of large amount of worldwide and regional geological information allowed suggesting necessity of more intensive research of massive crust formation and diamondiferous magmatism epochs, which were paid little attention to. Presently available highly scattered information allows distinguishing two megastages in formation of the Siberian platform diamondiferousness. The early stage includes the time from Archean to Riphean or from diamonds formation in the mantle to its first appearance at the surface conditions. Polycentrism, localization at peripheral parts of the platform, as well as diversity of transporters are characteristic for this megastage. The second megastage (Early Paleozoic-Eocene differs from the first one by spatial arrangement of occurrences, monocentrism, and prevalence of kimberlite diatremes. During planning and carrying out the diamonds prospecting works on perspective territories of the platform, it is necessary to study not only Middle-Paleozoic productive collectors, but also more ancient (Preсambrian and Lower Paleozoic and young (Mesozoic strata as well, performing detailed complex analysis of  rock composition (especially the key layers and basal horizons.

  10. Topological defects in epithelia govern cell death and extrusion

    Science.gov (United States)

    Saw, Thuan Beng; Doostmohammadi, Amin; Nier, Vincent; Kocgozlu, Leyla; Thampi, Sumesh; Toyama, Yusuke; Marcq, Philippe; Lim, Chwee Teck; Yeomans, Julia M.; Ladoux, Benoit

    2017-04-01

    Epithelial tissues (epithelia) remove excess cells through extrusion, preventing the accumulation of unnecessary or pathological cells. The extrusion process can be triggered by apoptotic signalling, oncogenic transformation and overcrowding of cells. Despite the important linkage of cell extrusion to developmental, homeostatic and pathological processes such as cancer metastasis, its underlying mechanism and connections to the intrinsic mechanics of the epithelium are largely unexplored. We approach this problem by modelling the epithelium as an active nematic liquid crystal (that has a long range directional order), and comparing numerical simulations to strain rate and stress measurements within monolayers of MDCK (Madin Darby canine kidney) cells. Here we show that apoptotic cell extrusion is provoked by singularities in cell alignments in the form of comet-shaped topological defects. We find a universal correlation between extrusion sites and positions of nematic defects in the cell orientation field in different epithelium types. The results confirm the active nematic nature of epithelia, and demonstrate that defect-induced isotropic stresses are the primary precursors of mechanotransductive responses in cells, including YAP (Yes-associated protein) transcription factor activity, caspase-3-mediated cell death, and extrusions. Importantly, the defect-driven extrusion mechanism depends on intercellular junctions, because the weakening of cell-cell interactions in an α-catenin knockdown monolayer reduces the defect size and increases both the number of defects and extrusion rates, as is also predicted by our model. We further demonstrate the ability to control extrusion hotspots by geometrically inducing defects through microcontact printing of patterned monolayers. On the basis of these results, we propose a mechanism for apoptotic cell extrusion: spontaneously formed topological defects in epithelia govern cell fate. This will be important in predicting

  11. Coherent amplified optical coherence tomography

    Science.gov (United States)

    Zhang, Jun; Rao, Bin; Chen, Zhongping

    2007-07-01

    A technique to improve the signal-to-noise ratio (SNR) of a high speed 1300 nm swept source optical coherence tomography (SSOCT) system was demonstrated. A semiconductor optical amplifier (SOA) was employed in the sample arm to coherently amplify the weak light back-scattered from sample tissue without increasing laser power illuminated on the sample. The image quality improvement was visualized and quantified by imaging the anterior segment of a rabbit eye at imaging speed of 20,000 A-lines per second. The theory analysis of SNR gain is given followed by the discussion on the technologies that can further improve the SNR gain.

  12. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    Constraints in the implementation of models of blended learning can be explained by several causes, but in this paper, it is illustrated that lack of sense of coherence is a major factor of these constraints along with the referential whole of the perceived learning environments. The question...... of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections upon these terms...... and conditions if the student shall be able acquire the necessary competencies....

  13. Coherence, Pseudo-Coherence, and Non-Coherence.

    Science.gov (United States)

    Enkvist, Nils Erik

    Analysis of the factors that make a text coherent or non-coherent suggests that total coherence requires cohesion not only on the textual surface but on the semantic level as well. Syntactic evidence of non-coherence includes lack of formal agreement blocking a potential cross-reference, anaphoric and cataphoric references that do not follow their…

  14. Numerical Studies of Low Cycle Fatigue in Forward Extrusion Dies

    DEFF Research Database (Denmark)

    Pedersen, Thomas Ø

    2000-01-01

    Forward extrusion dies typically fail due to transverse fatigue cracks or wear. Fatigue cracks are initiated in regions where the material is subjected to repeated plastic deformations, e.g. the transition radius in a forward extrusion die, in the present work, a material model capable of describ...

  15. 75 FR 34482 - Certain Aluminum Extrusions From China

    Science.gov (United States)

    2010-06-17

    ... Commission, Washington, DC, and by publishing the notice in the Federal Register of April 6, 2010 (75 FR... COMMISSION Certain Aluminum Extrusions From China Determinations On the basis of the record \\1\\ developed in... reason of imports from China of certain aluminum extrusions, provided for in subheadings 7604.21,...

  16. 76 FR 29007 - Certain Aluminum Extrusions From China

    Science.gov (United States)

    2011-05-19

    ... in the Federal Register on December 22, 2010 (75 FR 80527). The hearing was held in Washington, DC... COMMISSION Certain Aluminum Extrusions From China Determinations On the basis of the record \\1\\ developed in... certain aluminum extrusions from ] China other than finished heat sinks, provided for in subheadings...

  17. Material testing of copper by extrusion-cutting

    DEFF Research Database (Denmark)

    Segalina, F.; De Chiffre, Leonardo

    2017-01-01

    was developed and implemented on a CNC lathe. An investigation was carried out extrusion-cutting copper discs using high-speed-steel cutting tools at 100 m/min cutting speed. Flow stress values for copper under machining-relevant conditions were obtained from measurement of the extrusion-cutting force...

  18. CAD implementation of design rules for aluminium extrusion dies

    NARCIS (Netherlands)

    Ouwerkerk, van Gijs

    2009-01-01

    Aluminium extrusion is an industrial forming process that is used to produce long profiles of a constant cross-section. This cross-section is shaped by the opening in a steel tool known as the die. The understanding of the mechanics of the aluminium extrusion process is still limited. The flow of al

  19. Coherence and Sense of Coherence

    DEFF Research Database (Denmark)

    Dau, Susanne

    2014-01-01

    of coherence is both related to conditional matters as learning environments, structure, clarity and linkage but also preconditioned matters and prerequisites among participants related to experiences and convenience. It is stressed that this calls for continuous assessment and reflections upon these terms...... and conditions if the student shall be able acquire the necessary competencies....

  20. Abl suppresses cell extrusion and intercalation during epithelium folding.

    Science.gov (United States)

    Jodoin, Jeanne N; Martin, Adam C

    2016-09-15

    Tissue morphogenesis requires control over cell shape changes and rearrangements. In the Drosophila mesoderm, linked epithelial cells apically constrict, without cell extrusion or intercalation, to fold the epithelium into a tube that will then undergo epithelial-to-mesenchymal transition (EMT). Apical constriction drives tissue folding or cell extrusion in different contexts, but the mechanisms that dictate the specific outcomes are poorly understood. Using live imaging, we found that Abelson (Abl) tyrosine kinase depletion causes apically constricting cells to undergo aberrant basal cell extrusion and cell intercalation. abl depletion disrupted apical-basal polarity and adherens junction organization in mesoderm cells, suggesting that extruding cells undergo premature EMT. The polarity loss was associated with abnormal basolateral contractile actomyosin and Enabled (Ena) accumulation. Depletion of the Abl effector Enabled (Ena) in abl-depleted embryos suppressed the abl phenotype, consistent with cell extrusion resulting from misregulated ena Our work provides new insight into how Abl loss and Ena misregulation promote cell extrusion and EMT.

  1. Friction measurement and modelling in forward rod extrusion

    DEFF Research Database (Denmark)

    Tan, Xincai; Bay, Niels; Zhang, Wenqi

    2003-01-01

    Forward extrusion is one of the important processes in bulk metal forming. Friction stress can be estimated from the slope of the load±displacement curve at the steady state after the maximum load in a forward extrusion test. In this paper, forward rod extrusion tests are carried out to determine...... experimentally friction stress at various normal pressures, reductions in area, billet heights and lubrications. Tested materials include aluminium alloy, low carbon steel and stainless steel. Two lubrication methods are applied, conversion coating followed by either alkaline soap or molybdenum disulphide...... as the lubricant. Friction stresses are obtained from measurements of slopes of extrusion pressure±punch travel curves at the steady state stage. Normal pressures are evaluated by using Mohr’s circle, in which shear ¯ow stresses are estimated at the maximum elastic deformation points from the same extrusion...

  2. Nature of the mantle roots beneath the North American craton: mantle xenolith evidence from Somerset Island kimberlites

    Science.gov (United States)

    Schmidberger, S. S.; Francis, D.

    1999-09-01

    The recently discovered Nikos kimberlite on Somerset Island, in the Canadian Arctic, hosts an unusually well preserved suite of mantle xenoliths dominated by garnet-peridotite (lherzolite, harzburgite, dunite) showing coarse and porphyroclastic textures, with minor garnet-pyroxenite. The whole rock and mineral data for 54 Nikos xenoliths indicate a highly refractory underlying mantle with high olivine forsterite contents (ave. Fo=92.3) and moderate to high olivine abundances (ave. 80 wt.%). These characteristics are similar to those reported for peridotites from the Archean Kaapvaal and Siberian cratons (ave. olivine Fo=92.5), but are clearly distinct from the trend defined by oceanic peridotites and mantle xenoliths in alkaline basalts and kimberlites from post-Archean continental terranes (ave. olivine Fo=91.0). The Nikos xenoliths yield pressures and temperatures of last equilibration between 20 and 55 kb and 650 and 1300°C, and a number of the peridotite nodules appear to have equilibrated in the diamond stability field. The pressure and temperature data define a conductive paleogeotherm corresponding to a surface heat flow of 44 mW/m 2. Paleogeotherms based on xenolith data from the central Slave province of the Canadian craton require a lower surface heat flow (˜40 mW/m 2) indicating a cooler geothermal regime than that beneath the Canadian Arctic. A large number of kimberlite-hosted peridotites from the Kaapvaal craton in South Africa and parts of the Siberian craton are characterized by high orthopyroxene contents (ave. Kaapvaal 32 wt.%, Siberia 20 wt.%). The calculated modal mineral assemblages for the Nikos peridotites show moderate to low contents of orthopyroxene (ave. 12 wt.%), indicating that the orthopyroxene-rich mineralogy characteristic of the Kaapvaal and Siberian cratons is not a feature of the cratonic upper mantle beneath Somerset Island.

  3. The Sytykanskaya kimberlite pipe: Evidence from deep-seated xenoliths and xenocrysts for the evolution of the mantle beneath Alakit, Yakutia, Russia

    OpenAIRE

    Ashchepkov, I.V.; A.M. Logvinova; L.F. Reimers; Ntaflos, T.; Z.V. Spetsius; Vladykin, N.V.; Downes, Hilary; Yudin, D.S.; Travin, A.V.; I.V. Makovchuk; Palesskiy, V.S.; Khmel'nikova, O.S.

    2015-01-01

    Mantle xenoliths (>150) and concentrates from late autolithic breccia and porphyritic kimberlite from the Sytykanskaya pipe of the Alakit field (Yakutia) were analyzed by EPMA and LAM ICP methods. In P-T-X-f(O2) diagrams minerals from xenoliths show widest variations, the trends P-Fe#-CaO, f(O2) for minerals from porphyric kimberlites are more stepped than for xenocrysts from breccia. Ilmenite PTX points mark moving for protokimberlites from the lithosphere base (7.5 GPa) to pyroxenite lens (...

  4. The composition of volatile components in olivines from Yakutian kimberlites of various ages: Evidence from gas chromatography-mass spectrometry

    Science.gov (United States)

    Tomilenko, A. A.; Bul'bak, T. A.; Khomenko, M. O.; Kuzmin, D. V.; Sobolev, N. V.

    2016-06-01

    The composition of volatiles from fluid and melt inclusions in olivine phenocrysts from Yakutian kimberlite pipes of various ages (Olivinovaya, Malokuonapskaya, and Udachnaya-East) were studied for the first time by gas chromatography-mass spectrometry. It was shown that hydrocarbons and their derivatives, as well as nitrogen-, halogen-, and sulfur-bearing compounds, played a significant role in the mineral formation. The proportion of hydrocarbons and their derivatives in the composition of mantle fluids could reach 99%, including up to 4.9% of chlorineand fluorine-bearing compounds.

  5. Stable isotope paleoclimatology of the earliest Eocene using kimberlite-hosted mummified wood from the Canadian Subarctic

    Science.gov (United States)

    Hook, B. A.; Halfar, J.; Gedalof, Z.; Bollmann, J.; Schulze, D. J.

    2015-10-01

    The recent discovery of well-preserved mummified wood buried within a subarctic kimberlite diamond mine prompted a paleoclimatic study of the early Eocene "hothouse" (ca. 53.3 Ma). At the time of kimberlite eruption, the Subarctic was warm and humid producing a temperate rainforest biome well north of the Arctic Circle. Previous studies have estimated that mean annual temperatures in this region were 4-20 °C in the early Eocene, using a variety of proxies including leaf margin analysis and stable isotopes (δ13C and δ18O) of fossil cellulose. Here, we examine stable isotopes of tree-ring cellulose at subannual- to annual-scale resolution, using the oldest viable cellulose found to date. We use mechanistic models and transfer functions to estimate earliest Eocene temperatures using mummified cellulose, which was well preserved in the kimberlite. Multiple samples of Piceoxylon wood within the kimberlite were crossdated by tree-ring width. Multiple proxies are used in combination to tease apart likely environmental factors influencing the tree physiology and growth in the unique extinct ecosystem of the Polar rainforest. Calculations of interannual variation in temperature over a multidecadal time-slice in the early Eocene are presented, with a mean annual temperature (MAT) estimate of 11.4 °C (1 σ = 1.8 °C) based on δ18O, which is 16 °C warmer than the current MAT of the area (-4.6 °C). Early Eocene atmospheric δ13C (δ13Catm) estimates were -5.5 (±0.7) ‰. Isotopic discrimination (Δ) and leaf intercellular pCO2 ratio (ci/ca) were similar to modern values (Δ = 18.7 ± 0.8 ‰; ci/ca = 0.63 ± 0.03 %), but intrinsic water use efficiency (Early Eocene iWUE = 211 ± 20 μmol mol-1) was over twice the level found in modern high-latitude trees. Dual-isotope spectral analysis suggests that multidecadal climate cycles somewhat similar to the modern Pacific Decadal Oscillation likely drove temperature and cloudiness trends on 20-30-year timescales, influencing

  6. Extrusion Pretreatment of Lignocellulosic Biomass: A Review

    Directory of Open Access Journals (Sweden)

    Jun Zheng

    2014-10-01

    Full Text Available Bioconversion of lignocellulosic biomass to bioethanol has shown environmental, economic and energetic advantages in comparison to bioethanol produced from sugar or starch. However, the pretreatment process for increasing the enzymatic accessibility and improving the digestibility of cellulose is hindered by many physical-chemical, structural and compositional factors, which make these materials difficult to be used as feedstocks for ethanol production. A wide range of pretreatment methods has been developed to alter or remove structural and compositional impediments to (enzymatic hydrolysis over the last few decades; however, only a few of them can be used at commercial scale due to economic feasibility. This paper will give an overview of extrusion pretreatment for bioethanol production with a special focus on twin-screw extruders. An economic assessment of this pretreatment is also discussed to determine its feasibility for future industrial cellulosic ethanol plant designs.

  7. Eulerian hydrocode modeling of a dynamic tensile extrusion experiment (u)

    Energy Technology Data Exchange (ETDEWEB)

    Burkett, Michael W [Los Alamos National Laboratory; Clancy, Sean P [Los Alamos National Laboratory

    2009-01-01

    Eulerian hydrocode simulations utilizing the Mechanical Threshold Stress flow stress model were performed to provide insight into a dynamic extrusion experiment. The dynamic extrusion response of copper (three different grain sizes) and tantalum spheres were simulated with MESA, an explicit, 2-D Eulerian continuum mechanics hydrocode and compared with experimental data. The experimental data consisted of high-speed images of the extrusion process, recovered extruded samples, and post test metallography. The hydrocode was developed to predict large-strain and high-strain-rate loading problems. Some of the features of the features of MESA include a high-order advection algorithm, a material interface tracking scheme and a van Leer monotonic advection-limiting. The Mechanical Threshold Stress (MTS) model was utilized to evolve the flow stress as a function of strain, strain rate and temperature for copper and tantalum. Plastic strains exceeding 300% were predicted in the extrusion of copper at 400 m/s, while plastic strains exceeding 800% were predicted for Ta. Quantitative comparisons between the predicted and measured deformation topologies and extrusion rate were made. Additionally, predictions of the texture evolution (based upon the deformation rate history and the rigid body rotations experienced by the copper during the extrusion process) were compared with the orientation imaging microscopy measurements. Finally, comparisons between the calculated and measured influence of the initial texture on the dynamic extrusion response of tantalum was performed.

  8. Optimal design of an extrusion process for a hinge bracket

    Energy Technology Data Exchange (ETDEWEB)

    Na, Geum Ju; Jang, Myung Geun; Kim, Jong Bong [Seoul National University, Seoul (Korea, Republic of)

    2016-05-15

    This study considers process design in forming a hinge bracket. A thin hinge bracket is typically produced by bending a sheet panel or welding a hollow bar into a sheet panel. However, the hinge bracket made by bending or welding does not have sufficient durability in severe operating conditions because of the stress concentration in the bended region or the low corrosion resistance of the welded region. Therefore, this study uses forming to produce the hinge bracket part of a foldable container and to ensure durability in difficult operating conditions. An extrusion process for a T-shaped hinge bracket is studied using finite element analysis. Preliminary analysis shows that a very high forging load is required to form the bracket by forging. Therefore, extrusion is considered as a candidate process. Producing the part through the extrusion process enables many brackets to be made in a single extrusion and through successive cutting of the extruded part, thereby reducing the manufacturing cost. The design focuses on reducing the extrusion load and on ensuring shape accuracy. An initial billet is designed to reduce the extrusion load and to obtain a geometrically accurate part. The extruded part is bent frequently because of uneven material flow. Thus, extrusion die geometries are designed to obtain straight parts.

  9. Epithelial cell extrusion leads to breaches in the intestinal epithelium.

    Science.gov (United States)

    Liu, Julia J; Davis, Elisabeth M; Wine, Eytan; Lou, Yuefei; Rudzinski, Jan K; Alipour, Misagh; Boulanger, Pierre; Thiesen, Aducio L; Sergi, Consolato; Fedorak, Richard N; Muruve, Daniel; Madsen, Karen L; Irvin, Randall T

    2013-04-01

    Two distinct forms of intestinal epithelial cell (IEC) extrusion are described: 1 with preserved epithelial integrity and 1 that introduced breaches in the epithelial lining. In this study, we sought to determine the mechanism underlying the IEC extrusion that alters the permeability of the gut epithelium. IEC extrusions in polarized T84 monolayer were induced with nigericin. Epithelial permeability was assessed with transepithelial electrical resistance and movements of latex microspheres and green fluorescent protein-transfected Escherichia coli across the monolayer. In vivo IEC extrusion was modulated in wild-type and a colitic (interleukin-10 knock-out) mouse model with caspase-1 activation and inhibition. Luminal aspirates and mucosal biopsies from control patients and patients with inflammatory bowel disease were analyzed for caspase-1 and caspase-3&7 activation. Caspase-1-induced IEC extrusion in T84 monolayers resulted in dose-dependent and time-dependent barrier dysfunction, reversible with caspase-1 inhibition. Moreover, the movements of microspheres and microbes across the treated epithelial monolayers were observed. Increased caspase-1-mediated IEC extrusion in interleukin-10 knock-out mice corresponded to enhanced permeation of dextran, microspheres, and translocation of E. coli compared with wild type. Caspase-1 inhibition in interleukin-10 knock-out mice resulted in a time-dependent reduction in cell extrusion and normalization of permeability to microspheres. Increased IEC extrusion in wild-type mice was induced with caspase-1 activation. In human luminal aspirates, the ratio of positively stained caspase-1 to caspase-3&7 cells were 1:1 and 2:1 in control patients and patients with inflammatory bowel disease, respectively; these observations were confirmed by cytochemical analysis of mucosal biopsies. IEC extrusion mediated by caspase-1 activation contributes to altered intestinal permeability in vitro and in vivo.

  10. Towards Extrusion of Ionomers to Process Fuel Cell Membranes

    Directory of Open Access Journals (Sweden)

    Jean-Yves Sanchez

    2011-07-01

    Full Text Available While Proton Exchange Membrane Fuel Cell (PEMFC membranes are currently prepared by film casting, this paper demonstrates the feasibility of extrusion, a solvent-free alternative process. Thanks to water-soluble process-aid plasticizers, duly selected, it was possible to extrude acidic and alkaline polysulfone ionomers. Additionally, the feasibility to extrude composites was demonstrated. The impact of the plasticizers on the melt viscosity was investigated. Following the extrusion, the plasticizers were fully removed in water. The extrusion was found to impact neither on the ionomer chains, nor on the performances of the membrane. This environmentally friendly process was successfully validated for a variety of high performance ionomers.

  11. EXTRUSION DIE CAE OF THE STEEL REINFORCED PLASTIC PIPE

    Institute of Scientific and Technical Information of China (English)

    W.Q. Ma; H.Y. Sun; D.C. Kang; K.D. Zhao

    2004-01-01

    The steel reinforced plastic pipe is a new kind of pressure pipe. It is made up with steel wires and plastic. Because reinforced skeleton of the steel wire increase the complexity of plastic flow during the extrusion phase, the traditional design criteria of extrusion die is not suitable. The study on extrusion die of the kind of pipe is very important step in produce development. Using finite element (FE) method in this paper, the flow rule of molten plastic inside the die has been predicted and a group of optimal structural parameters was obtained. These results are helpful for reducing the design cycle and improve the quality of the final product.

  12. Study On Extrusion Technological Parameters Of Brown Rice

    Institute of Scientific and Technical Information of China (English)

    Zhu Yongyi; Zhou Xianqing; Ling Lizhong

    2001-01-01

    Extrusion is an efficient measure to improve the texture and physic-s of brown rice. The polynomial degree two model of extrusion parameters and gelatinized degree, water absorption index, water soluble index and moisture content of extruded matter was obtained by methods of single factor and response surface methodology, R2=0.9649, 0.8745, 0.9079, 0.8677. The optimal parameters of brown rice extrusion were figured out as follows:moisture nrice, 11.42%, speed of screw, 30rpm, feeding speed, and 20rpm.

  13. A new engineering model for understanding extrusion process

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    A new engineering method is proposed to understand extrudate expansion and extrusion operation parameters for starch based food extrusion cooking process through dimensional analysis principle, i.e. Buckingham pi theorem. Three dimensionless groups, i.e. pump efficiency, water content...... and temperature, are suggested to describe the extrudate expansion. Using the three dimensionless groups, an equation is derived to express the extrudate expansion. The model has been used to correlate the experimental data for whole wheat flour and fish feed extrusion cooking. The average deviations...

  14. Orthodontic extrusion in the transitional dentition: a simple technique.

    LENUS (Irish Health Repository)

    Darby, Laura J

    2009-11-01

    Extrusion of teeth may be necessary in cases of delayed eruption, primary retention, traumatically intruded teeth, or subgingivally fractured teeth. Removable appliances are advantageous, as anchorage is not as tooth-dependant as in the case of fixed appliances. They are cost-effective, operator friendly, and a valuable treatment option to consider in cases where extrusion of anterior teeth in the transitional dentition is necessary. The purpose of this paper was to describe a simple, cost-effective technique using a removable appliance for extrusion of incisors in the transitional dentition.

  15. Calibrator device for the extrusion of cable coatings

    Science.gov (United States)

    Garbacz, Tomasz; Dulebová, Ľudmila; Spišák, Emil; Dulebová, Martina

    2016-05-01

    This paper presents selected results of theoretical and experimental research works on a new calibration device (calibrators) used to produce coatings of electric cables. The aim of this study is to present design solution calibration equipment and present a new calibration machine, which is an important element of the modernized technology extrusion lines for coating cables. As a result of the extrusion process of PVC modified with blowing agents, an extrudate in the form of an electrical cable was obtained. The conditions of the extrusion process were properly selected, which made it possible to obtain a product with solid external surface and cellular core.

  16. Experimental investigation and numerical simulation of large-sized aluminum tube extrusion forming

    Institute of Scientific and Technical Information of China (English)

    吕亚臣; 骆俊廷; 马春荣; 徐岩

    2008-01-01

    Large-sized aluminum tube has big section effect, aspect ratio and thin thickness, so that the extrusion technology is complex and the large specific pressure is generated in extrusion cavity. The temperature variation and velocity effect is difficult to control. The extrusion forming of large-sized aluminum tube was researched and simulated. Three-dimensional thermo-mechanical coupled finite element model was constructed and appropriate boundary conditions were given out. The results show that large-sized aluminum tube can be formed by isothermal extrusion through controlling the extrusion velocity and founding the relationship between extrusion velocity and extrusion temperature.

  17. Major- and Trace-Element Compositions of Indicator Minerals that Occur as Macro- and Megacrysts, and of Xenoliths, from Kimberlites in Northeastern Angola

    Directory of Open Access Journals (Sweden)

    Monica Escayola

    2012-10-01

    Full Text Available In this study, we compare the major- and trace-element compositions of olivine, garnet, and clinopyroxene that occur as single crystals (142 grains, with those derived from xenoliths (51 samples from six kimberlites in the Lucapa area, northeastern Angola: Tchiuzo, Anomaly 116, Catoca, Alto Cuilo-4, Alto Cuilo-63 and Cucumbi-79. The samples were analyzed using electron probe microanalysis (EPMA and laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS. The results suggest different paragenetic associations for these kimberlites in the Lucapa area. Compositional overlap in some of the macrocryst and mantle xenolith samples indicates a xenocrystic origin for some of those macrocrysts. The presence of mantle xenocrysts suggests the possibility of finding diamond. Geothermobarometric calculations were carried out using EPMA data from xenoliths by applying the program PTEXL.XLT. Additional well calibrated single-clinopyroxene thermobarometric calculations were also applied. Results indicate the underlying mantle experienced different equilibration conditions. Subsequent metasomatic enrichment events also support a hypothesis of different sources for the kimberlites. These findings contribute to a better understanding of the petrogenetic evolution of the kimberlites in northeastern Angola and have important implications for diamond exploration.

  18. ROLE OF MELT EXTRUSION IN THE ENHANCEMENT OF BIOAVAILABILITY

    Directory of Open Access Journals (Sweden)

    Sahil Bansode* and S. S. Poddar

    2012-11-01

    Full Text Available Starting from plastic industry, today melt extrusion has found its place in the array of pharmaceutical manufacturing processes. Melt extrusion processes are currently applied in the pharmaceutical field for the formulation of variety of dosage forms such as granules, pellets, tablets, implants, transdermal systems & ophthalmic inserts. This technology represents an efficient pathway for increasing the solubility of poorly soluble drugs. The process forms a solid dispersion where the drug is presented in an amorphous & molecularly dispersed state in a carrier. This leads to an increase in solubility, as no lattice energy has to be overcome during dissolution. Melt extrusion is considered to be an efficient technology in the field of formulation of solid dispersions to improve bioavailability with particular advantages over solvent processes. This article highlights on the technology of Hot Melt Extrusion (HME.

  19. Effect of extrusion parameters on some properties of dietary fiber ...

    African Journals Online (AJOL)

    use

    2011-11-21

    Nov 21, 2011 ... The independent variables studied were extrusion temperature (from. 59.77 to ... The extraction of juice from citrus fruits, such as oranges, grapefruit ..... properties of extruded orange pulp and its effect on the quality of cookies.

  20. The friction in rod forward and backward micro extrusion

    Directory of Open Access Journals (Sweden)

    J. Piwnik

    2010-01-01

    Full Text Available Micro parts are increasingly applied in industry because of the trend to miniaturization every day devices. Microforming is a method of manufacturing metal micro elements using a plastic treatment. This kind of production ensures high productivity, shapes and dimensions repeatability and good surface quality. Size effect connected with small dimensions affects changes in treatment processes of micro parts. While forming in micro scale, surface roughness is size independent and does not decrease with decreasing detail dimensions. The article presents schemas for forward and backward extrusion of metal rods. Using FEM, tool’s roughness as a triangle wave has been assumed, taking into account thereby size effect. Influence of roughness on extrusion forces by comparison with traditional flat tools and constant friction shear factor m has been specified. Impact of roughness caused growth of extrusion forces while forward extruding. On the contrary, backward extrusion ensured stable required forces, regardless of a surface structure.

  1. CHARACTERIZATION OF NEW TOOL STEEL FOR ALUMINUM EXTRUSION DIES

    Directory of Open Access Journals (Sweden)

    José Britti Bacalhau

    2014-06-01

    Full Text Available Aluminum extrusion dies are an important segment of application on industrial tools steels, which are manufactured in steels based on AISI H13 steel. The main properties of steels applied to extrusion dies are: wear resistance, impact resistance and tempering resistance. The present work discusses the characteristics of a newly developed hot work steel to be used on aluminum extrusion dies. The effects of Cr and Mo contents with respect to tempering resistance and the Al addition on the nitriding response have been evaluated. From forged steel bars, Charpy impact test and characterization via EPMA have been conducted. The proposed contents of Cr, Mo, and Al have attributed to the new VEX grade a much better tempering resistance than H13, as well as a deeper and harder nitrided layer. Due to the unique characteristics, this new steel provides an interesting alternative to the aluminum extrusion companies to increase their competitiveness.

  2. Encapsulation of orange terpenes investigating a plasticisation extrusion process.

    Science.gov (United States)

    Tackenberg, Markus W; Krauss, Ralph; Schuchmann, Heike P; Kleinebudde, Peter

    2015-01-01

    Extrusion is widely used for flavour encapsulation. However, there is a lack of process understanding. This study is aimed at improving the understanding of a counter rotating twin screw extrusion process. Orange terpenes as model flavour, maltodextrin and sucrose as matrix materials, and a water feed rate between 4.0% and 5.7% were applied. Product temperatures < 80 °C and specific mechanical energy inputs <260 Wh/kg resulted. Amorphous and partly crystalline samples were obtained. The loss of crystalline sucrose was linked to a dissolution process of the sugar in the available water amount. Melting of the excipients did not arise, resulting in a plasticisation extrusion process. Maximally 67% of the flavour was retained (corresponding to a 4.1% product flavour load). The flavour loss correlated with insufficient mixing during the process and flavour evaporation after extrusion. Based on these results, recommendations for an improved encapsulation process are given.

  3. Applications of polymer extrusion technology to coal processing

    Science.gov (United States)

    Lewis, D. W.

    1981-01-01

    Upon heating, many of the middle-aged bituminous coals exhibit a plasticity very similar to polyethylene for a few minutes. Plastic coal can be extruded, pelletized or molded using common plastics technology and equipment. Investigations concerning the plastic state of coals are conducted with the objective to develop techniques which will make useful commercial applications of this property possible. Experiments which show the characteristics of plastic-state coal are discussed, and problems related to a continuous extrusion of coal are considered. Probably the most significant difference between the continuous extrusion of coal and the extrusion of a thermoplastic polymer is that volatiles are continuously being released from the coal. Attention is given to aspects of dragflow, solids feeding, and melt pumping. Application potentials for plastic coal extrusion might be related to coal gasification, direct liquefaction, and coal combustion.

  4. Diamonds from the Juina-5 kimberlite provide evidence for crustal volatile recycling into the deep Earth

    Science.gov (United States)

    Thomson, Andrew; Walter, Michael; Kohn, Simon; Burnham, Antony; Bulanova, Galina; Smith, Chris; Araujo, Debora

    2014-05-01

    'Superdeep' diamonds originate from a depth range spanning the asthenospheric upper mantle, transition zone and shallowest parts of the lower mantle [1]. Sporadically they entrap small inclusions of pre-existing or co-precipitating minerals during their crystallisation from volatile-rich melts or fluids. Such samples therefore preserve important petrologic, tectonic and geodynamic information about their growth environment together with evidence of the deep volatile cycling. The Juina-5 kimberlite has previously been recognised as a source of 'superdeep' diamonds [2]. Here we present and discuss data from an extended collection of Juina-5 diamonds. This work has revealed that these diamonds are dominantly composed of isotopically light carbon and contain a mineral inclusion cargo mostly of eclogitic affinity consisting of many former Mg- and Ca-perovskite, NAL-phase, CF-phase, stishovite, majoritic garnet, sodic pyroxene, ferropericlase, Fe or Fe-carbide and sulphide minerals. Together these observations suggest that the diamonds form from material of a subducted crustal origin. The high enrichment of the inclusions' trace element compositions implies that they cannot represent trapped fragments of formerly subsolidus mantle material. Geochemical modelling instead allows the compositions of Ca-perovskite and majorite inclusions to be directly linked to formation from a slab-derived carbonate bearing melt. It is suggested that the formation of 'superdeep' diamonds, and their inclusions, is the result of 'redox-freezing' during the interaction of oxidised slab melts and reducing mantle rocks [3]. It is expected that such melts will be produced during slab foundering and thermal equilibration in the upper/lower mantle boundary region, where tomographic evidence suggests slab subduction often stalls [4]. This hypothesis has been tested with experiments performed at transition zone pressures using the multi-anvil apparatus. At 20 GPa the composition of a low degree melt

  5. Polycrystalline diamond aggregates from the Mir kimberlite pipe, Yakutia: Evidence for mantle metasomatism

    Science.gov (United States)

    Sobolev, N. V.; Shatsky, V. S.; Zedgenizov, D. A.; Ragozin, A. L.; Reutsky, V. N.

    2016-11-01

    Polycrystalline diamond aggregates (boart, framesites, diamondites) have been widely studied but their origin is poorly understood. We report the results of a study in situ of two polished fragments of fine-grained (40-400 μm size of individual diamond grains) dense polycrystalline diamond aggregates from the Mir pipe containing visible multiple interstitial garnet inclusions. They were analyzed for major and trace elements of inclusions and one of them - for δ13C and N abundance and isotopic composition of host diamonds. These aggregates are classified as variety IX by Orlov (1977). No cavities were observed in these samples. Sixty two irregular garnet grains and one clinopyroxene inclusion were detected and analyzed in sample Mr 832. Garnets are homogeneous within single grains but variable in Mg# [100Mg/(Mg + Fe)] from 60 up to 87 and CaO contents (3.3-5.3 wt.%) among grains with a trend to negative correlation. Low Cr (550-640 ppm) confirms eclogitic (E-type) paragenesis. High Na2O contents (5.2 wt.%) of a single pyroxene inclusion are additional evidence of eclogitic nature of this sample. Wide variations in trace elements (ppm) are characteristic for garnet grains: Sr (2.7-25.6), Y (9.7-14.1), Zr (15.6-38.7) and positive Eu anomaly is present. The δ13C of diamonds within studied sample is variable (- 6.4 ÷- 9.8 ‰) as well as N abundance (75-1150 ppm) and δ15N - 27, - 38, - 58 ‰. The second peridotitic (U/P-type) sample Mr 838 contains eight inclusions of Mg-rich Cr-pyropes (Mg# 85, Cr2O3 3.2-3.4 wt.%) and magnesite inclusion with 4.35 wt.% FeO and 1.73 wt.% CaO. Trace element content in pyropes is relatively uniform (ppm): Sr (0.4-1.6), Y (13.2-13.4) and Zr (13.0). We conclude that heterogeneous distribution of the trace elements among garnet grains in Mr 832 and magnesite presence in Mr 838 are indicative of the effects of mantle metasomatism and rapid crystallization shortly before the eruption of the kimberlite.

  6. Extrusion and properties of lead zirconate titanate piezoelectric ceramics

    DEFF Research Database (Denmark)

    Cai, S.; Millar, C.E.; Pedersen, L.

    1997-01-01

    The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates was investi......The purpose of this work was to develop a procedure for fabricating electroceramic actuators with good piezoelectric properties. The preparation of lead zirconate titanate (PZT) piezoelectric ceramic rods and tubes by extrusion processing is described. The microstructure of extrudates...

  7. Making Ceramic/Polymer Parts By Extrusion Stereolithography

    Science.gov (United States)

    Stuffle, Kevin; Mulligan, A.; Creegan, P.; Boulton, J. M.; Lombardi, J. L.; Calvert, P. D.

    1996-01-01

    Extrusion stereolithography developmental method of computer-controlled manufacturing of objects out of ceramic/polymer composite materials. Computer-aided design/computer-aided manufacturing (CAD/CAM) software used to create image of desired part and translate image into motion commands for combination of mechanisms moving resin dispenser. Extrusion performed in coordination with motion of dispenser so buildup of extruded material takes on size and shape of desired part. Part thermally cured after deposition.

  8. Encapsulation of Liquids Via Extrusion--A Review.

    Science.gov (United States)

    Tackenberg, Markus W; Kleinebudde, Peter

    2015-01-01

    Various encapsulation techniques are known for pharmaceutical applications. Extrusion is of minor importance. However, extrusion is used to obtain granules with encapsulate liquid active ingredients (AI) like essential oils and flavours for food applications since decades. Many of these AIs can be used for agrochemical, home care, and pharmaceutical products, too. Thus, the focus of this review is on the interdisciplinary presentation and evaluation of the available knowledge about the encapsulation process via extrusion. The desired microcapsule structure is discussed at the outset. The microcapsule is compared to the alternative glassy solid solution system, before an overview of suitable excipients is given. In the next section the development of the extrusion technique, used for encapsulation processes, is presented. Thereby, the focus is on encapsulation using twin-screw extruders. Additionally, the influence of the downstream processes on the products is discussed, too. The understanding of the physical processes during extrusion is essential for specifically adjustment of the desired product properties and thus, highlighted in this paper. Unfortunately not all processes, especially the mixing process, are well studied. Suggestions for further studies, to improve process understanding and product quality, are given, too. The last part of this review focuses on the characterization of the obtained granules, especially AI content, encapsulation efficiency, and storage stability. In conclusion, extrusion is a standard technique for flavour encapsulation, but future studies, may lead to more (pharmaceutical) applications and new products.

  9. Experimental and numerical investigation of ram extrusion of bread dough

    Science.gov (United States)

    Mohammed, M. A. P.; Wanigasooriya, L.; Charalambides, M. N.

    2016-10-01

    An experimental and numerical study on ram extrusion of bread dough was conducted. A laboratory ram extrusion rig was designed and manufactured, where dies with different angles and exit radii were employed. Rate dependent behaviour was observed from tests conducted at different extrusion speeds, and higher extrusion pressure was reported for dies with decreasing exit radius. A finite element simulation of extrusion was performed using the adaptive meshing technique in Abaqus. Simulations using a frictionless contact between the billet and die wall showed that the model underestimates the response at high entry angles. On the other hand, when the coefficient of friction value was set to 0.09 as measured from friction experiments, the dough response was overestimated, i.e. the model extrusion pressure was much higher than the experimentally measured values. When a critical shear stress limit, τmax, was used, the accuracy of the model predictions improved. The results showed that higher die angles require higher τmax values for the model and the experiments to agree.

  10. The effect of gas assisted length on polymer melt extrusion based on the gas-assisted extrusion technique

    Science.gov (United States)

    Wan, B.; Ren, Z.; Liu, G. D.; Huang, X. Y.

    2017-02-01

    In this study, the gas-assisted technique was used into the process of polymer melt extrusion to overcome the extrudate swell problem. The gas length is an important factors in the gas-assisted extrusion technique. To ascertain the mechanism of the gas-assisted extrusion technique, and to determine the optimal gas length, the effect of gas length on the extrudate swell ratio of melt was numerically investigated. In finite element numerical simulation, PTT constitutive model and full slip boundary condition were used to achieve the gas-assisted mode. Compared with the traditional no gas-assisted extrusion, numerical results showed that the extrudate swell problem was well eliminated by the gas-assisted method. Moreover, the extrudate swell of melt decreased with the increasing of the gas length because the pressure and shear stress of melt were greatly decreased. Moreover, the flow velocity of melt is uniform at the die outlet.

  11. Weld formation during material extrusion additive manufacturing.

    Science.gov (United States)

    Seppala, Jonathan E; Hoon Han, Seung; Hillgartner, Kaitlyn E; Davis, Chelsea S; Migler, Kalman B

    2017-08-18

    Material extrusion (ME) is a layer-by-layer additive manufacturing process that is now used in personal and commercial production where prototyping and customization are required. However, parts produced from ME frequently exhibit poor mechanical performance relative to those from traditional means; moreover, fundamental knowledge of the factors leading to development of inter-layer strength in this highly non-isothermal process is limited. In this work, we seek to understand the development of inter-layer weld strength from the perspective of polymer interdiffusion under conditions of rapidly changing mobility. Our framework centers around three interrelated components: in situ thermal measurements (via infrared imaging), temperature dependent molecular processes (via rheology), and mechanical testing (via mode III fracture). We develop the concept of an equivalent isothermal weld time and test its relationship to fracture energy. For the printing conditions studied the equivalent isothermal weld time for Tref = 230 °C ranged from 0.1 ms to 100 ms. The results of these analysis provide a basis for optimizing inter-layer strength, the limitations of the ME process, and guide development of new materials.

  12. Viscoplastic flow in an extrusion damper

    CERN Document Server

    Syrakos, Alexandros; Georgiou, Georgios C; Tsamopoulos, John

    2016-01-01

    Numerical simulations of the flow in an extrusion damper are performed using a finite volume method. The damper is assumed to consist of a shaft, with or without a spherical bulge, oscillating axially in a containing cylinder filled with a viscoplastic material of Bingham type. The response of the damper to a forced sinusoidal displacement is studied. In the bulgeless case the configuration is the annular analogue of the well-known lid-driven cavity problem, but with a sinusoidal rather than constant lid velocity. Navier slip is applied to the shaft surface in order to bound the reaction force to finite values. Starting from a base case, several problem parameters are varied in turn in order to study the effects of viscoplasticity, slip, damper geometry and oscillation frequency to the damper response. The results show that, compared to Newtonian flow, viscoplasticity causes the damper force to be less sensitive to the shaft velocity; this is often a desirable damper property. The bulge increases the required...

  13. Mitotic chromosome compaction via active loop extrusion

    Science.gov (United States)

    Goloborodko, Anton; Imakaev, Maxim; Marko, John; Mirny, Leonid; MIT-Northwestern Team

    During cell division, two copies of each chromosome are segregated from each other and compacted more than hundred-fold into the canonical X-shaped structures. According to earlier microscopic observations and the recent Hi-C study, chromosomes are compacted into arrays of consecutive loops of ~100 kilobases. Mechanisms that lead to formation of such loop arrays are largely unknown. Here we propose that, during cell division, chromosomes can be compacted by enzymes that extrude loops on chromatin fibers. First, we use computer simulations and analytical modeling to show that a system of loop-extruding enzymes on a chromatin fiber self-organizes into an array of consecutive dynamic loops. Second, we model the process of loop extrusion in 3D and show that, coupled with the topo II strand-passing activity, it leads to robust compaction and segregation of sister chromatids. This mechanism of chromosomal condensation and segregation does not require additional proteins or specific DNA markup and is robust against variations in the number and properties of such loop extruding enzymes. Work at NU was supported by the NSF through Grants DMR-1206868 and MCB-1022117, and by the NIH through Grants GM105847 and CA193419. Work at MIT was supported by the NIH through Grants GM114190 R01HG003143.

  14. PEACH POMACE PROCESSING USING TWIN SCREW EXTRUSION

    Directory of Open Access Journals (Sweden)

    Preetam Sarkar

    2014-02-01

    Full Text Available Fruit by-products have found limited applications in the food industry. They have been primarily used as animal feed, applied to agricultural land for soil amendment or composted and applied to farms for growing crops. Some of these disposal methods are not environment friendly, while others are costly. This study was undertaken to examine the possibility of utilizing peach pomace as a source of soluble dietary fiber in expanded extruded food products. Peach pomace was combined with rice flour at four different levels. The four blends were mixed, dried to a moisture level of 13.5% (w/w and ground to flour. These blends were extruded in a twin-screw extruder (Clextral EV-25 at a feed flow rate of 15 kg/h. The extruded products were analyzed for physical and textural properties. The apparent and true densities for the extrudates decreased from 183.93 to 133.94 kg/m3 and 1275.31 to 1171.2 kg/m3, respectively. A linear increase in extrudate porosity (85.11-88.54% and radial expansion ratio (13.5-19.3 and a steady decrease in breaking strength (104-50.74 kPa were observed with increasing peach pomace level in the blends. This study demonstrates the potential of extrusion processing as a tool for fruit by-product utilization, which will not only enhance consumption of soluble dietary fiber but will also increase the overall fruit utilization.

  15. Découverte d'un diatrème de kimberlite diamantifère à Séguéla en Côte-d'IvoireDiscovery of a diamond-bearing kimberlite diatreme at Séguéla in Ivory Coast

    Science.gov (United States)

    Pouclet, André; Allialy, Marc; Daouda-Yao, Bertin; Esso, Botty

    2004-01-01

    The Séguéla area in Ivory Coast is known for its diamond-bearing field related to dykes of kimberlite and lamproite. These dykes, devoid of any deformation and metamorphism, crosscut the Birimian formations. Their N 170° orientation is controlled by the tectonized contact between the Archean and the Paleoproterozoic shields of the West-African craton. Discovery of a diatreme, with its pipe breccias and well-preserved maar sediments, below the present-day colluvia, attests for the probable recent geological age (Cretaceous?) of the kimberlitic activity. To cite this article: A. Pouclet et al., C. R. Geoscience 336 (2004).

  16. Probing Archean lithosphere using the Lu-Hf isotope systematics of peridotite xenoliths from Somerset Island kimberlites, Canada

    Science.gov (United States)

    Schmidberger, Stefanie S.; Simonetti, Antonio; Francis, Don; Gariépy, Clément

    2002-04-01

    A knowledge of the Hf isotopic composition of the subcontinental lithosphere beneath Archean cratons is essential to constrain the Hf isotope budget of the Earth's mantle. Hf isotopic measurements were obtained by MC-ICP-MS for a suite of refractory peridotite xenoliths and constituent garnets from the Nikos kimberlite (100 Ma) on Somerset Island in order to constrain the isotopic composition and age of the lithosphere beneath the northern Canadian craton. The low-temperature Nikos peridotites (Somerset lithosphere, are characterized by higher 176Lu/ 177Hf ratios (0.03-0.05) and Hf isotopic values ( 176Hf/ 177Hf (0.1Ga)=0.28296-0.28419) than the deep-seated high-temperature peridotites (>1100°C; 0.004-0.03, 0.28265-0.28333, respectively). These differences in Hf isotope signatures suggest that shallow and deep subcontinental lithosphere beneath Somerset Island represent isotopically distinct domains and do not share a common petrogenetic history. The Lu-Hf isotope systematics of the shallow low-temperature peridotites define a positively sloped line that plot along a 2.8 Ga reference isochron. A number of these peridotites are characterized by highly radiogenic Hf isotopic compositions suggestive of long-term radiogenic ingrowth (billions of years). These findings are consistent with an interpretation that the shallow Somerset lithosphere (to depths of ˜150 km) stabilized in the Archean. The majority of the high-temperature peridotites plot closer to the composition of the host kimberlite. Although the observed isotopic variation may be attributed in part to kimberlite-related Hf addition, it is possible that these deep-seated xenoliths represent younger mantle. The superchondritic 176Lu/ 177Hf ratios observed for a number of the shallow low-temperature peridotites indicate strong fractionation of Lu and Hf, suggesting mantle root formation in the garnet stability field (depths >80 km). The Hf isotope compositions for the Somerset low-temperature peridotites

  17. Density structure of the cratonic mantle in Southern Africa. 2. Correlations with kimberlite distribution, seismic velocities, and Moho sharpness

    DEFF Research Database (Denmark)

    Artemieva, Irina; Vinnik, Lev

    2016-01-01

    across) lowdensity (down to 3.34 g/cm3) and high-density (up to 3.41 g/cm3) anomalies. High (3.40–3.42 g/cm3) mantle densities beneath the Eastern Cape Fold belt require the presence of a significant amount of eclogite in the mantle, such as associated with subducted oceanic slabs. We find a strong...... the composition and rheology of the lithospheric mantle to make it unfavorable for consequent kimberlite eruptions. (5) Density anomalies in the lithospheric mantle show inverse correlation with seismic Vp, Vs velocities at 100–150 km depth. However, this correlation is weaker than reported in experimental...

  18. Reconstruction of burial history of eroded Mesozoic strata using kimberlite shale xenoliths, volcaniclastic and crater facies, Northwest Territories, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Stasiuk, Lavern D.; Sweet, Art R.; Issler, Dale R. [Natural Resources Canada, Geological Survey of Canada-Calgary, 3303-33rd ST N.W., Calgary AB, Canada (T2L 2A7)

    2006-01-03

    Reconstruction of Mesozoic and Cenozoic sedimentary 'cover' on the Precambrian shield in the Lac de Gras diamond field, Northwest Territories, Canada, has been achieved using Cretaceous and early Tertiary sedimentary xenoliths and contemporaneous organic matter preserved in volcaniclastic sediments associated with late Cretaceous to early Tertiary kimberlite pipe intrusions, and in situ, Eocene crater lake, lacustrine and peat bog strata. Percent reflectance in oil (%Ro) of vitrinite within shale xenoliths for: (i) Albian to mid-Cenomanian to Turonian ranges from >0.27 to 0.42 %Ro (mean 0.38 %Ro), (ii) Maastrichtian to early Paleocene from 0.24 to <0.30%; (iii) latest Paleocene to early middle Eocene 0.15 to <0.23 %Ro (mean = 0.18 %Ro). These levels of thermal maturity are corroborated by Rock Eval pyrolysis T{sub max} ({sup o}C) and VIS region fluorescence of liptinites, with wavelengths of maximum emission for sporinite, prasinophyte alginite and dinoflagellates consistent with vitrinite reflectance of 0.20 to <0.50 %Ro. Burial-thermal history modeling, constrained by measured vitrinite reflectance and porosity of shale xenoliths, predicts a maximum burial temperature for Mid to Late Albian strata ({approx}115 Ma) of 60 {sup o}C with {approx}1.2 to 1.4 km of Cretaceous strata in the Lac de Gras kimberlite field region prior to major uplift and erosion, which began at 90 Ma. Late Paleocene to middle Eocene volcanic crater lake lacustrine to peat bog strata were only buried to a few hundreds of meters and are in a peat-brown coal stage of thermal maturation. (author)

  19. New model of the mantle lithosphere beneath Kuoyka kimberlite field Yakutia.

    Science.gov (United States)

    Ashchepkov, Igor; Kostrovitsky, Sergey; Ovchinnikov, Yury; Tychkov, Nikolai; Khmelnikova, Olga; Palessky, Stanislav

    2013-04-01

    New data for the 11 pipes from Kuoyka field show that high Cr2O3 garnets to 10- 12% as well as high Cr chromites (to 64%Cr2O3) are found in several more pipes Zaozernaya, Seraya, Slyudyanka, Vodorasdelnaya, Titan, Lusya in addition to Djanga pipe. All garnets belong o lherzolite field and not less than 1/3 are TiO rich. The TiO2 rich chromites are dominating in the Cr- rich population. Metasomatic Cr2O3- rich (to 6%) ilmenites pre in the MgO and TiO2- part of the variation diagrams. The Cr- diopside variations show high variations of Fe and Na content to 4 % suggesting the hybridic origin similar to the Cr- pyroxeneis from Obnazhennaya pyroxenites (Taylor et al ., 2003). Omphicites (to 7 % Na2O) are rare. Cr-amphiboles (pargasites and hornblendes) are common in the upper part of the SCLM as well as in the Anabar and Kharamai region. Reconstructions of the mantle sections show the deep lithospheric roots beneath the Zosernaya pipe (7.5 GPa) traced by the PT conditions for Opx, Cpx, Gar, Cr and Ilm. SCLM is divided in to 4 sections and Ilm trace tow intervals in lower and upper part form 4 GPa. Th HT branch is sporadically found from 7 GPa to the Moho. In other pipes ilmenite and garnet PT estimates are more common in the lower part o mantle section while the Cpx trace mainly middle part of SCLM similar to the Obnazhennaya pip. It seems that kimberlites captured mainly the walls of feeders traced by Cr- low garnets and ilmenites in the lower part of SCLM while peridotitic mantle column was captured starting from the middle part of SCLM. The NS transsect of the Kuoyka field show more fertile mantle sections in the NNW part of the field. The TRE determined for the minerals from Kuoyka field show rather rounded patterns for REE of garnets with high variations in HREE part and small elevation in LREE . The depleted compositions reval the inflection in Eu TRE spidergrams well as relatively small Sr minima. Many of them show Ta peak, relatively small Pb elevation and Th

  20. Evolution of the mantle sections beneath the kimberlite pipes example of Yakutia.

    Science.gov (United States)

    Ashchepkov, Igor; Ntaflos, Ttheodoros; Logvinova, Alla; Vladykin, Nikolai; Ivanov, Alexandr; Spetsius, Zdislav; Stegnitsky, Yury; Kostrovitsky, Sergei; Salikhov, Ravil; Makovchuk, Igor; Shmarov, Gleb; Karpenko, Mikhail; Downes, Hilary; Madvedev, Nikolai

    2017-04-01

    of most Ilmenites but more regular for the Cpx and Garnets revealing the sub parallel patterns elevating LREE with the rising TRE. But commonly these are not continuous sequances because they developed in the pulsing moving systems like beneath Zarnitsa. The minerals from the feeders like dunites also show the inflected or S-type REE patterns. From the earlier to later phases the TRE compositions became more evolved reflecting the evolution of protokimberlites. The wall rocks also often show the interaction with the more evolved melts and sometimes "cut" spectrums due to the dissolution some phases and repeated melting events So we could suggest the joint evolution of the mantle column protokimberlites and megacrysts composition and type of kimberlites with the diamond grade. The mantle lithospheric base captured by the PK. The developing and rising protokimbelrites was followed by the crystallization of the diamonds in the gradient in FO2 zone in wall rocks due to reductions of C -bearing fluids and carbonatites (> 1 QMF) on peridotites ((< -2 -5 QMF). The most intensive reactions are near the graphite - diamond boundary where protokimberlites are breaking and where most framesites are forming. Grant RBRF 16-05-000860Grant RBRF 16-05-000860

  1. Mitochondrial Extrusion through the cytoplasmic vacuoles during cell death.

    Science.gov (United States)

    Nakajima, Akihito; Kurihara, Hidetake; Yagita, Hideo; Okumura, Ko; Nakano, Hiroyasu

    2008-08-29

    Under various conditions, noxious stimuli damage mitochondria, resulting in mitochondrial fragmentation; however, the mechanisms by which fragmented mitochondria are eliminated from the cells remain largely unknown. Here we show that cytoplasmic vacuoles originating from the plasma membrane engulfed fragmented mitochondria and subsequently extruded them into the extracellular spaces in undergoing acute tumor necrosis factor alpha-induced cell death in a caspase-dependent fashion. Notably, upon fusion of the membrane encapsulating mitochondria to the plasma membrane, naked mitochondria were released into the extracellular spaces in an exocytotic manner. Mitochondrial extrusion was specific to tumor necrosis factor alpha-induced cell death, because a genotoxic stress-inducing agent such as cisplatin did not elicit mitochondrial extrusion. Moreover, intact actin and tubulin cytoskeletons were required for mitochondrial extrusion as well as membrane blebbing. Furthermore, fragmented mitochondria were engulfed by cytoplasmic vacuoles and extruded from hepatocytes of mice injected with anti-Fas antibody, suggesting that mitochondrial extrusion can be observed in vivo under pathological conditions. Mitochondria are eliminated during erythrocyte maturation under physiological conditions, and anti-mitochondrial antibody is detected in some autoimmune diseases. Thus, elucidating the mechanism underlying mitochondrial extrusion will open a novel avenue leading to better understanding of various diseases caused by mitochondrial malfunction as well as mitochondrial biology.

  2. Uniformity and continuity of effective strain in AZ91D processed by multi-pass equal channel angular extrusion

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-hua; LUO Shou-jing; DU Zhi-ming

    2008-01-01

    AZ91D magnesium alloy was processed by equal channel angular extrusion(ECAE). The influence of extrusion temperature, extrusion pass and extrusion route on the ultimate strength of the extruded billet was analyzed. The process of multi-pass extrusion was simulated with the method of finite element analysis, and the continuity and uniformity of effective strain in multi-pass extrusion were investigated. The results show that extrusion pass plays the most important role in improving the ultimate strength of AZ91D magnesium alloy, the extrusion route is the second, and the extrusion temperature is the last. From the numerical simulation, there exists the continuity of the accumulated deformation in multi-pass extrusion and the effective strain increases linearly. The tendency of the strain uniformity is different in multi-pass extrusion with extrusion routes. The results of experiment agree with those of numerical simulation.

  3. Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole.

    Science.gov (United States)

    Hengsawas Surasarang, Soraya; Keen, Justin M; Huang, Siyuan; Zhang, Feng; McGinity, James W; Williams, Robert O

    2017-05-01

    The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ-polymer binary mixtures generated from Flory-Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80 °C for 5 min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80 °C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon(®) VA 64, degraded at 180 °C and 140 °C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon(®) VA 64, Soluplus(®) and Eudragit(®) E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon(®) VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon(®) VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.

  4. A novel polymer extrusion micropelletization process

    Science.gov (United States)

    Aquite, William

    Polymer micropellets provide a variety of potential applications for different processes in the polymer industry. Conventional pellets are in the size range of 2.5 mm to 5 mm, while micropellets are at least ten times smaller, in the size range of 50 μm to 1000 μm. The potential benefits to a processor using micropellets include: high surface to volume ratio, high bulk density, fast and even melting rates in extrusion, improved dry flow properties, faster injection molding cycles, and consequently lower energy consumption during processing. More specialized sintering processes that require polymer powders, such as selective sintering techniques, microporous plastics parts manufacturing, and other powder sintering methods would benefit from the production of polymer micropellets since these exhibit the advantages of pellets yet have a lower average size. This work focuses on the study of a technique developed at the Polymer Engineering Center. The technique uses a microcapillary die for the production of micropellets by causing instabilities in extruded polymer threads deformed using an air stream. Tuning of process conditions allow the development of surface disturbances that promote breakup of the threads into pellets, which are subsequently cooled and collected. Although micropellets with high sphericity and a narrow size distribution can be produced using this technique, minimal changes in process conditions also lead to the production of lenticular pellets as well as pellets, fibers and threads with a wide range of size and shape distributions. This work shows how changing processing conditions achieve a variety of shapes and sizes of micropellets, broadening its application for the production of powders from a variety of polymer resins. Different approaches were used, including dimensional analysis and numerical simulation of the micropelletization process. This research reveals the influence of non-linear viscoelastic effects on the dispersion of a polymer

  5. FEM and FVM compound numerical simulation of aluminum extrusion processes

    Institute of Scientific and Technical Information of China (English)

    周飞; 苏丹; 彭颖红; 阮雪榆

    2003-01-01

    The finite element method (FEM) and the finite volume method (FVM) numerical simulation methods have been widely used in forging industries to improve the quality of products and reduce the costs. Because of very concentrative large deformation during the aluminum extrusion processes, it is very difficult to simulate the whole forming process only by using either FEM or FVM. In order to solve this problem, an FEM and FVM compound simulation method was proposed. The theoretical equations of the compound simulation method were given and the key techniques were studied. Then, the configuration of the compound simulation system was established. The tube extrusion process was simulated successfully so as to prove the validity of this approach for aluminum extrusion processes.

  6. Stress Analysis and Optimum Design of Hot Extrusion Dies

    Institute of Scientific and Technical Information of China (English)

    帅词俊; 肖刚; 倪正顺

    2004-01-01

    A three-dimensional model of a hot extrusion die was developed by using ANSYS software and its second development language-ANSYS parametric design language.A finite element analysis and optimum design were carried out.The three-dimensional stress diagram shows that the stress concentration is rather severe in the bridge of the hot extrusion die, and that the stress distribution is very uneven.The optimum dimensions are obtained.The results show that the optimum height of the extrusion die is 89.596 mm.The optimum radii of diffluence holes are 65.048 mm and 80.065 mm.The stress concentration is reduced by 27%.

  7. NUMERICAL DESIGN OF DIE LAND FOR SHAPE EXTRUSION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the extrusion of shapes with flat-faced die,the proper design of die land is of critical importance in avoiding the generations of geometry defects.A methodology for the design of die land,which consists of a simulation-adjustment iteration,is proposed.The metal flow in extrusion is simulated by the three dimensional finite element method and the die land is adjusted according to the simulation result.Both the formulae for adjustment of the die land and the criterion for the judgment of proper die land are suggested.The extrusion of an L-section shape is chosen as the computational example and the result is compared with the industrial design.

  8. Die land optimization of section extrusion by finite element method

    Institute of Scientific and Technical Information of China (English)

    卫兴华; 田柱平

    2001-01-01

    In the extrusion of sections with flat-faced die, the proper design of die land is critically important in avoid ing geometry defects. A methodology for the design of die land, which consists of a simulation-adjustment iteration, isproposed. The metal flow in extrusion is simulated by the three dimensional finite element method and the die land is adjusted according to the simulation result. The simulation-adjustment iteration is conducted repeatedly until the uniform metal flow in die land exit is obtained. Both the formulae for adjustment of the die land and the criterion for the judgment of proper die land are suggested. The extrusion of a C-section is chosen as the computational example.

  9. Diffusion between glass and metals for optical fiber preform extrusion

    Science.gov (United States)

    Yeo, Felicia Yan Xin; Zhang, Zhifeng; Kumar Chakkathara Janardhanan Nair, Dileep; Zhang, Yilei

    2015-07-01

    When silica is extruded, diffusion of metal atoms into silica results contamination to the silica being heated, and thus is a serious concern for the glass extrusion process, such as extrusion of glass fiber preform. This paper examines diffusion between fused silica and two high strength metals, the stainless steel SS410 and the superalloy Inconel 718, at 1000 °C and under the normal atmosphere condition by SEM and Electron Dispersion Spectrum. It is found that diffusion occurs between silica and SS410, and at the same time, SS410 is severely oxidized during diffusion experiment. On the contrary, the diffusion between Inconel 718 and silica is unnoticeable, suggesting excellent high temperature performance of Inconel 718 for glass extrusion.

  10. Instant blend from cassava derivatives produced by extrusion

    Directory of Open Access Journals (Sweden)

    Fernanda Rossi Moretti Trombini

    2016-03-01

    Full Text Available ABSTRACT: The current research aimed to evaluate the effects of extrusion parameters on the physical characteristics of extruded blends of cassava leaf flour and starch. A factorial central composite design with four independent variables and the response surface methodology were used to evaluate the results of color parameters (L*, a*, b*, water absorption index, water solubility index and paste properties, according to the variations in the leaf flour percentage (1.5 to 7.5%, extrusion temperature (60 to 100ºC, screw speed (175 to 231rpm and moisture (20 to 30%. Extrusion conditions affect color, water absorption and water solubility indexes and paste properties of blends. The intermediate tested conditions of variable parameters lead to obtain extruded products with higher cold viscosity and water absorption index and light color, desirable qualities for rapid preparation products.

  11. Microfabrication of three-dimensional filters for liposome extrusion

    Science.gov (United States)

    Baldacchini, Tommaso; Nuñez, Vicente; LaFratta, Christopher N.; Grech, Joseph S.; Vullev, Valentine I.; Zadoyan, Ruben

    2015-03-01

    Liposomes play a relevant role in the biomedical field of drug delivery. The ability of these lipid vesicles to encapsulate and transport a variety of bioactive molecules has fostered their use in several therapeutic applications, from cancer treatments to the administration of drugs with antiviral activities. Size and uniformity are key parameters to take into consideration when preparing liposomes; these factors greatly influence their effectiveness in both in vitro and in vivo experiments. A popular technique employed to achieve the optimal liposome dimension (around 100 nm in diameter) and uniform size distribution is repetitive extrusion through a polycarbonate filter. We investigated two femtosecond laser direct writing techniques for the fabrication of three-dimensional filters within a microfluidics chip for liposomes extrusion. The miniaturization of the extrusion process in a microfluidic system is the first step toward a complete solution for lab-on-a-chip preparation of liposomes from vesicles self-assembly to optical characterization.

  12. The phenomenon of durability variable dies for aluminum extrusion profiles

    Directory of Open Access Journals (Sweden)

    J. Borowski

    2016-04-01

    Full Text Available Extrusion dies are usually regenerated several times (min 4 times. The phenomenon of extended life after each regenerative nitriding process has not been explained. In this work, the regeneration process of dies used in the extrusion of aluminium profiles has been presented. In the article, it was sought to explain the cause of increased die durability after the third or fourth nitriding. Also in this work is presented an analysis of the influence of the parameters of gas nitriding with the ZeroFlow method on hardness of dies. Results were verified under industrial conditions at extrusion company, comparing the durability of the dies nitrided with the ZeroFlow method with so-far-used dies nitrided in the commercial way. An increase of the dies durability was achieved after a single ZeroFlow nitriding.

  13. Satellite Based Extrusion Rates for the 2006 Augustine Eruption

    Science.gov (United States)

    Dehn, J.; Bailey, J. E.; Dean, K. G.; Skoog, R.; Valcic, L.

    2006-12-01

    Extrusion rates were calculated from polar orbiting infrared satellite data for the 2006 eruption of Augustine Volcano, Alaska. The pixel integrated brightness temperatures from the satellite data were converted to estimates of ground temperature by making assumptions and using first hand observations about the geometry of the hot area (lava dome, flows and pyroclastic flow deposits) relative to the cold area in the kilometer scale pixels. Extrusion rate is calculated by assuming that at a given temperature, a lava emits an amount of radiation proportional to its volume. On ten occasions during the activity, helicopter based infrared imagers were used to validate the satellite observations. The pre-January 11 thermal activity was not significantly above background in satellite data. The first strong thermal anomalies were recorded during the first explosive phase on January 11. During successive explosive phases in January, bright thermal signals were observed, often saturating the sensors. Large areas (many km2) were observed to be warm in the satellite data, indicative of pyroclastic flows. Sometime during or after January 29, during a phase of sustained ash emission, the thermal signal became persistent, suggesting the beginning of lava effusion. The extrusion rates derived from satellite data varied from 0 to nearly 7 m3/s, giving an eruption rate of 2.7 m3/s. The extrusion event produced two blocky lava flows which moved down the north flank of the volcano. Extrusion occurred through at least March 15 (day 76) when a sharp drop in extrusion rate and thermal signal is observed. Based on the derived extrusion rates, it is estimated that 18 million m3 of lava was extruded during the course of the eruption. This value agreed well with photogrammetric measurements, but does not agree with volumes derived through subtraction of digital elevation models post- and pre- eruption. It should be noted that the thermal approach only works for hot lavas, and does not

  14. The effect of extrusion conditions on the properties and textures of AZ31B alloy

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2017-06-01

    Full Text Available The effect of extrusion conditions on the tensile properties and texture of AZ31B alloy has been investigated by means of optical microscopy (OM, scanning electron microscopy (SEM, electron backscattered diffraction (EBSD and tensile tests. It is found that the ultimate tensile strength (UTS, the yield strength (YS and elongation (EN of the extruded AZ31B alloy are more significantly influenced by extrusion velocities in contrast with temperature. Although the extrusion conditions are different, the {112¯0} 〈011¯0〉 texture is the chief texture in the AZ31B after extrusion. Moreover, the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity. As the extrusion velocity is raised at the same temperature, the orientation density of textures increases and the separated textures become relatively concentrated. This leads to the changes of tensile properties at different extrusion conditions.

  15. What garnet, clinopyroxene, and diamond potential can tell us about the evolution of sub-cratonic mantle sections: a case study of the Zagadochnaya kimberlite (Yakutia)

    OpenAIRE

    Ziberna, Luca

    2013-01-01

    This PhD provides major and trace element compositions for a new suite of Cr-rich garnet xenocrysts and associated minerals from the diamond-free Zagadochnaya kimberlite, Daldyn Field, Yakutia (Russia). Interpreting the nature and evolution of the underlying lithospheric mantle from these samples requires a good understanding of relationships between pressures and temperatures of formation, upper mantle phase relations and trace element signatures of petrochemical processes. I addressed these...

  16. Cohering power of quantum operations

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Kaifeng, E-mail: bkf@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China); Kumar, Asutosh, E-mail: asukumar@hri.res.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Zhang, Lin, E-mail: linyz@zju.edu.cn [Institute of Mathematics, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Junde, E-mail: wjd@zju.edu.cn [School of Mathematical Sciences, Zhejiang University, Hangzhou 310027 (China)

    2017-05-18

    Highlights: • Quantum coherence. • Cohering power: production of quantum coherence by quantum operations. • Study of cohering power and generalized cohering power, and their comparison for differentmeasures of quantum coherence. • Operational interpretation of cohering power. • Bound on cohering power of a generic quantum operation. - Abstract: Quantum coherence and entanglement, which play a crucial role in quantum information processing tasks, are usually fragile under decoherence. Therefore, the production of quantum coherence by quantum operations is important to preserve quantum correlations including entanglement. In this paper, we study cohering power–the ability of quantum operations to produce coherence. First, we provide an operational interpretation of cohering power. Then, we decompose a generic quantum operation into three basic operations, namely, unitary, appending and dismissal operations, and show that the cohering power of any quantum operation is upper bounded by the corresponding unitary operation. Furthermore, we compare cohering power and generalized cohering power of quantum operations for different measures of coherence.

  17. Feed extrusion process description Descrição do processo de extrusão do alimento

    Directory of Open Access Journals (Sweden)

    Galen J. Rokey

    2010-07-01

    Full Text Available The following work discusses the main features of feed extrusion process explaining the expected effects on the final product according to the raw material used as starch, protein, fat and fiber. The selection of processing equipments as feeder, preconditioner and extruder is discussed considering the involved costs and the probability of future expansion. Dryers are also essential in the extrusion process as it reduces the level of moisture in an extrusion cooked product. High moisture levels increase the water activity which favors the bacterial and mold growth so an overview of different kinds of dryers is considered. Guidelines for an economic prediction are shown to determine the potential for profit considering the input of raw material cost, energy cost and capital equipment cost as related to the extrusion module.Este trabalho aborda as principais características do processo de extrusão de alimentos, explicando os efeitos esperados no produto final, em função do tipo de componente utilizado na receita, como amido, proteínas, gorduras e fibras. O dimensionamento dos equipamentos da linha de extrusão, como silo, pré-condicionador e extrusor, é tratado considerando-se os custos envolvidos e a possibilidade de expansões futuras. Secadores também são essenciais no processo de extrusão, pois reduzem o nível de umidade do produto final. Altos níveis de umidade aumentam a atividade de água, favorecendo a proliferação de bactérias e mofo, portanto, uma visão geral de diferentes tipos de secadores é considerada. Orientações para uma previsão econômica são apresentadas para se determinar o potencial de lucro, considerando-se os custos com a matéria-prima, a energia utilizada no processo de fabricação e os equipamentos relacionados ao módulo de extrusão.

  18. Partially coherent imaging and spatial coherence wavelets

    CERN Document Server

    Castaneda, R

    2003-01-01

    A description of spatially partially coherent imaging based on the propagation of second order spatial coherence wavelets and marginal power spectra (Wigner distribution functions) is presented. In this dynamics, the spatial coherence wavelets will be affected by the system through its elementary transfer function. The consistency of the model with the both extreme cases of full coherent and incoherent imaging was proved. In the last case we obtained the classical concept of optical transfer function as a simple integral of the elementary transfer function. Furthermore, the elementary incoherent response function was introduced as the Fourier transform of the elementary transfer function. It describes the propagation of spatial coherence wavelets form each object point to each image point through a specific point on the pupil planes. The point spread function of the system was obtained by a simple integral of the elementary incoherent response function.

  19. Track with overlapping links for dry coal extrusion pumps

    Science.gov (United States)

    Saunders, Timothy; Brady, John D

    2014-01-21

    A chain for a particulate material extrusion pump includes a plurality of links, each of the plurality of links having a link body and a link ledge, wherein each link ledge of the plurality of links at least partially overlaps the link body of an adjacent one of the plurality of links.

  20. Load beam unit replaceable inserts for dry coal extrusion pumps

    Science.gov (United States)

    Saunders, Timothy; Brady, John D.

    2012-11-13

    A track assembly for a particulate material extrusion pump according to an exemplary aspect of the present disclosure includes a link assembly with a roller bearing. An insert mounted to a load beam located such that the roller bearing contacts the insert.

  1. Extrusion cooking with glucose supplementation reduced fumonisin concentrations and toxicity

    Science.gov (United States)

    Extrusion cooking involves forcing material through a heated barrel under high pressure using one (single-screw configuration) or two (twin-screw configuration) augers. We previously demonstrated (Bullerman et al., Journal of Agricultural and Food Chemistry 56:2400-2405, 2008; Voss et al., Journal o...

  2. 75 FR 17436 - Certain Aluminum Extrusions From China

    Science.gov (United States)

    2010-04-06

    ... amended, 67 FR 68036 (November 8, 2002). Even where electronic filing of a document is permitted, certain... Electronic Filing Procedures, 67 FR 68168, 68173 (November 8, 2002). In accordance with sections 201.16(c... COMMISSION Certain Aluminum Extrusions From China AGENCY: United States International Trade...

  3. MM98.36 Strain Paths in Extrusion

    DEFF Research Database (Denmark)

    Lindegren, Maria; Wiwe, Birgitte; Wanheim, Tarras

    1998-01-01

    The extrusion process has been investigated for different geometries, in order to study the strain path of different material elements during their movements through the plastic zone. This is done by using the FEM code DEFORM and physical simulation with wax togehter with the coefficient method...

  4. Protein Modifications after Foxtail Millet Extrusion: Solubility and Molecular Weight

    Directory of Open Access Journals (Sweden)

    Xuewei Zhao

    2015-03-01

    Full Text Available With the aim of illustrating the effects of extrusion cooking on the solubility of proteins in foxtail millet and their molecular basis, foxtail millet was extruded at five barrel temperature profiles and feed moisture contents. The proteins of raw and extrudate samples were extracted with six solutions sequentially. Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE of total protein and Starch Granule-Associate Protein (SGAP was performed. Extrusion caused a significant decrease in globulin, setarin and glutelin fractions with a corresponding increase in SDS- and SDS+2-ME-soluble and residual fractions. Increasing extrusion temperature or moisture content all led to SDS-soluble fraction decrease, while SDS+2-ME-soluble fraction increase. SDS-PAGE demonstrated that disulfide bond cross-linking occurred among glutelin and with setarin subunits. Extrusion had a less pronounced impact on the 60 kDa SGAP than the other middle-high molecular weight subunits. It is the protein-protein interaction shift from electrostatic force to hydrophobic and/or hydrogen forces and covalent disulfide cross-links that contributed to the decreased solubility of protein in foxtail millet extrudates.

  5. On Longitudinal Spectral Coherence

    DEFF Research Database (Denmark)

    Kristensen, Leif

    1979-01-01

    It is demonstrated that the longitudinal spectral coherence differs significantly from the transversal spectral coherence in its dependence on displacement and frequency. An expression for the longitudinal coherence is derived and it is shown how the scale of turbulence, the displacement between...

  6. Magma ascent, fragmentation and depositional characteristics of "dry" maar volcanoes: Similarities with vent-facies kimberlite deposits

    Science.gov (United States)

    Berghuijs, Jaap F.; Mattsson, Hannes B.

    2013-02-01

    , sufficiently large to drive magmatic fragmentation. Both eruptions were pulsating in intensity and relatively short-lived, with estimated durations of 23 and 10 h for Loolmurwak and Eledoi, respectively. The depositional characteristics of these maars, including the abundant occurrence of mantle xenoliths in the deposits, as well as their envisaged mode of emplacement show a strong similarity to the often poorly preserved vent-facies of kimberlitic diatremes. Therefore, future research on well-preserved melilititic maar-diatreme deposits may provide valuable insights into kimberlite emplacement processes.

  7. Interaction between protokimberlite melts and mantle lithosphere: Evidence from mantle xenoliths from the Dalnyaya kimberlite pipe, Yakutia (Russia

    Directory of Open Access Journals (Sweden)

    I.V. Ashchepkov

    2017-07-01

    Full Text Available The Dalnyaya kimberlite pipe (Yakutia, Russia contains mantle peridotite xenoliths (mostly lherzolites and harzburgites that show both sheared porphyroclastic (deformed and coarse granular textures, together with ilmenite and clinopyroxene megacrysts. Deformed peridotites contain high-temperature Fe-rich clinopyroxenes, sometimes associated with picroilmenites, which are products of interaction of the lithospheric mantle with protokimberlite related melts. The orthopyroxene-derived geotherm for the lithospheric mantle beneath Dalnyaya is stepped similar to that beneath the Udachnaya pipe. Coarse granular xenoliths fall on a geotherm of 35 mWm−2 whereas deformed varieties yield a 45 mWm−2 geotherm in the 2–7.5 GPa pressure interval. The chemistry of the constituent minerals including garnet, olivine and clinopyroxene shows trends of increasing Fe# (=Fe/(Fe + Mg with decreasing pressure. This may suggest that the interaction with fractionating protokimberlite melts occurred at different levels. Two major mantle lithologies are distinguished by the trace element patterns of their constituent minerals, determined by LA-ICP-MS. Orthopyroxenes, some clinopyroxenes and rare garnets are depleted in Ba, Sr, HFSE and MREE and represent relic lithospheric mantle. Re-fertilized garnet and clinopyroxene are more enriched. The distribution of trace elements between garnet and clinopyroxene shows that the garnets dissolved primary orthopyroxene and clinopyroxene. Later high temperature clinopyroxenes related to the protokimberlite melts partially dissolved these garnets. Olivines show decreases in Ni and increases in Al, Ca and Ti from Mg-rich varieties to the more Fe-rich, deformed and refertilized ones. Minerals showing higher Fe# (0.11–0.15 are found within intergrowths of low-Cr ilmenite-clinopyroxene-garnet related to the crystallization of protokimberlite melts in feeder channels. In P-f(O2 diagrams, garnets and Cr-rich clinopyroxenes

  8. Protein Stability during Hot Melt Extrusion: The Effect of Extrusion Temperature, Hydrophilicity of Polymers and Sugar Glass Pre-stabilization

    NARCIS (Netherlands)

    Teekamp, Naomi; Olinga, Peter; Frijlink, Henderik W.; Hinrichs, Wouter

    2015-01-01

    Purpose Biodegradable polymers have been widely investigated for controlled release formulations for protein delivery. However, the processing stability of proteins remains a major challenge. The aim of this research is to assess the influence of the hot melt extrusion process on the activity of a m

  9. Protein Stability during Hot Melt Extrusion : The Effect of Extrusion Temperature, Hydrophilicity of Polymers and Sugar Glass Pre-stabilization

    NARCIS (Netherlands)

    Teekamp, Naomi; Olinga, Peter; Hinrichs, Wouter; Frijlink, Henderik W.

    2015-01-01

    Purpose Biodegradable polymers have been widely investigated for controlled release formulations for protein delivery. However, the processing stability of proteins remains a major challenge. The aim of this research is to assess the influence of the hot melt extrusion process on the activity of a

  10. Complex fermion coherent states

    CERN Document Server

    Tyc, T; Sanders, B C; Oliver, W D; Tyc, Tomas; Hamilton, Brett; Sanders, Barry C.; Oliver, William D.

    2005-01-01

    Whereas boson coherent states provide an elegant, intuitive and useful representation, we show that the desirable features of boson coherent states do not carry over very well to fermion fields unless one is prepared to use exotic approaches such as Grassmann fields. Specifically, we identify four appealing properties of boson coherent states (eigenstate of annihilation operator, displaced vacuum state, preservation of product states under linear coupling, and factorization of correlators) and show that fermion coherent states, and approximations to fermion coherent states, defined over the complex field, do not behave well for any of these four criteria.

  11. Ram speed profile design for isothermal extrusion of AZ31 magnesium alloy by using FEM simulation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the conventional hot extrusion of metallic materials,the temperature of the workpiece varies during the whole extrusion process,leading to the non-uniformity of the product dimension,microstructure and properties.In the present research,a simulation model based on the principle of PID control was developed to establish ram speed profiles that can suppress the temperature evolution during the process to allow for isothermaI extrusion.With this simulation model,the real-time extrusion ram speed was adjusted according to the simulated exit temperature.The results show that temperature homogeneity is significantly improved not only along the extrudate length but also on its cross section in the case of extrusion in the isothermal mode with a designed ram speed profile in the extrusion process of AZ31 magnesium.In addition,die temperature varies over a more narrow range in comparison with extrusion in the conventional iso-speed mode.

  12. Rare earth element characteristics of pyrope garnets from the Kaavi-Kuopio kimberlites – implications for mantle metasomatism

    Directory of Open Access Journals (Sweden)

    Marjaleena Lehtonen

    2005-01-01

    Full Text Available Peridotitic garnet xenocrysts from five kimberlite pipes in the Kaavi-Kuopio area of eastern Finland have been studied using major and trace element geochemistry to obtain information on the stratigraphy, compositional variability and evolutionary history of the underlyinglithospheric mantle. Ni thermometry on garnet xenocrysts gives 650–1350°C and, when extrapolated to the geotherm determined using mantle xenoliths, indicates a sampling interval of c. 80–230 km. Three distinct mantle layers are recognized based on the xenolith/xenocryst record: (1 A shallow, 180 km, composed largely of fertile material. The chondrite-normalized REE profiles of subcalcic harzburgitic garnet xenocrysts originating from layer 2 bear evidence of an extensive ancient melt extraction event, similar to that observed in lithosphere underlying Archean cratons elsewhere. Memory of this eventhas possibly also been preserved in the REEN signatures of rare depleted garnets from layer 3 and in the CCGE pyropes from layer 1 despite their saturation in Ca. The lherzolitic and megacryst garnet varieties exhibit LREEN depletion relative to MREEN and HREEN, withthe steady enrichment from SmN to YbN typical of Ca-saturated mantle garnets. The enrichment of MREE and HREE probably derives from a metasomatic event caused by silicate melts close in composition to megacryst magma, which also imprinted a Ti-metasomatic overprint on many pyrope garnets. Harzburgitic and rare lherzolitic garnets, however, appear to have escaped this metasomatism.

  13. Sheared peridotite xenolith from the V. Grib kimberlite pipe, Arkhangelsk Diamond Province, Russia: Texture, composition, and origin

    Directory of Open Access Journals (Sweden)

    Alexey Vladimirovich Kargin

    2017-07-01

    Full Text Available The petrography and mineral composition of a mantle-derived garnet peridotite xenolith from the V. Grib kimberlite pipe (Arkhangelsk Diamond Province, Russia was studied. Based on petrographic characteristics, the peridotite xenolith reflects a sheared peridotite. The sheared peridotite experienced a complex evolution with formation of three main mineral assemblages: (1 a relict harzburgite assemblage consist of olivine and orthopyroxene porphyroclasts and cores of garnet grains (Gar1 with sinusoidal rare earth elements (REE chondrite C1 normalized patterns; (2 a neoblastic olivine and orthopyroxene assemblage; (3 the last assemblage associated with the formation of clinopyroxene and garnet marginal zones (Gar2. Major and trace element compositions of olivine, orthopyroxene, clinopyroxene and garnet indicate that both the neoblast and clinopyroxene-Gar2 mineral assemblages were in equilibrium with a high Fe-Ti carbonate-silicate metasomatic agent. The nature of the metasomatic agent was estimated based on high field strength elements (HFSE composition of olivine neoblasts, the garnet-clinopyroxene equilibrium condition and calculated by REE-composition of Gar2 and clinopyroxene. All these evidences indicate that the agent was a high temperature carbonate-silicate melt that is geochemically linked to the formation of the protokimberlite melt.

  14. A new flapless technique for crown lengthening after orthodontic extrusion.

    Science.gov (United States)

    Braga, Giovanni; Bocchieri, Anna

    2012-02-01

    Orthodontic extrusion (OE), which is performed in many different clinical situations to move a tooth or its periodontal tissues coronally, is often associated with supracrestal fiberotomy and root planing (OEFRP) or followed by surgical crown lengthening. The OEFRP procedure must be carried out every 2 weeks during the entire extrusive orthodontic phase, and precise control of the technique itself can be quite difficult, especially when this approach is to be performed on a limited portion of the root perimeter in teeth affected by angular defects. The aim of this study was to show a new nonsurgical crown-lengthening technique, performed shortly after the completion of OE, to simultaneously achieve proper hard and soft tissue architecture. Three different illustrative situations (periodontal pocket, root fracture, and root perforation) are described.

  15. Functionalization of whey proteins by reactive supercritical fluid extrusion

    Directory of Open Access Journals (Sweden)

    Khanitta Ruttarattanamongkol

    2012-09-01

    Full Text Available Whey protein, a by-product from cheese-making, is often used in a variety of food formulations due to its unsurpassednutritional quality and inherent functional properties. However, the possibilities for the improvement and upgrading of wheyprotein utilization still need to be explored. Reactive supercritical fluid extrusion (SCFX is a novel technique that has beenrecently reported to successfully functionalize commercially available whey proteins into a product with enhanced functionalproperties. The specific goal of this review is to provide fundamental understanding of the reinforcement mechanism andprocessing of protein functionalization by reactive SCFX process. The superimposed extrusion variables and their interactionmechanism affect the physico-chemical properties of whey proteins. By understanding the structure, functional properties andprocessing relationships of such materials, the rational design criteria for novel functionalized proteins could be developedand effectively utilized in food systems.

  16. The effect of grain size on dynamic tensile extrusion behaviour

    Directory of Open Access Journals (Sweden)

    Park Leeju

    2015-01-01

    Full Text Available Dynamic tensile extrusion (DTE tests were conducted on coarse grained and ultrafine grained (UFG OFHC Cu, Interstitial free (IF Steel, and pure Ta. Equal channel angular pressing (ECAP of 16passes with Bc for Cu, IF Steel and 4 passes for Ta was employed to fabricated UFG materials. DTE tests were carried out by launching the sphere samples (Dia. 7.62 mm to the conical extrusion die at a speed of ∼500 m/sec. The fragmentation behavior of the soft-recovered fragments were examined and compared with each other. The DTE fragmentation behavior of CG and UFG was numerically simulated by the LS-DYNA FEM code.

  17. HA/UHMWPE Nanocomposite Produced by Twin-screw Extrusion

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The HA/UHMWPE nanocomposite is compounded by twin-screw extrusion of the HA and UHMWPE powder mixture in paraffin oil and then compression molded to a sheet form. TGA measurement shows the HA weight loss after processing is about 1%-2% . FTIR spectra indicate the paraffin oil residue is trivial and UHMWPE is not oxidized. SEM reveals the HA nano particles are homogeneously dispersed by twin- screw extrusion and the inter-particle spaces are penetrated with UHMWPE fibrils by swelling treatment. HRTEM image indicates the HA particles and UHMWPE are intimately contacted by mechanical interlocking. Compared with the unfilled UHMWPE, stiffness of the composite with the HA volume fraction 0.23 was significantly enhanced to 9 times without detriment of the yield strength and the ductility.

  18. Some physicochemical properties of dextrin produced by extrusion process

    OpenAIRE

    2014-01-01

    Dextrinization of corn starch by twin screw extruder was studied. The effect of extruder operating conditions (five different screw speeds: 35, 45, 55, 65, and 70; and three temperatures: 125, 130, and 135 °C) on some physicochemical properties of dextrin (total soluble solid, water absorption index, water solubility index, and total color difference) was investigated. Results showed that as the screw speed and temperature of extrusion were increased the water absorption index of dextrin tend...

  19. An infrared investigation of inclusion-bearing diamonds from the Venetia kimberlite, Northern Province, South Africa : implications for diamonds from craton-margin settings

    Science.gov (United States)

    Viljoen, (Fanus)

    2002-08-01

    The Venetia kimberlites in the Northern Province of South Africa sampled diamonds from the lithosphere underlying the Central Zone of the Limpopo Belt. Given the general correlation of diamond-bearing kimberlites with old stable cratons, this tectonic setting is somewhat anomalous and, therefore, it is desirable to characterise the diamonds in terms of their infrared characteristics. A suite of diamonds of known paragenesis from the Venetia mine spans a large range of nitrogen concentrations from less than the detection limit to 1,355 ppm. Diamond nitrogen contents are, on average, higher in the eclogitic diamond population relative to the websteritic and peridotitic diamonds. Nitrogen aggregation states are variable, ranging from almost pure type IaA diamond (poorly aggregated nitrogen) to pure type IaB diamond (highly aggregated nitrogen). On a nitrogen aggregation diagram two distinct groups can be identified based on nitrogen content and nitrogen aggregation state. These are a minor population of diamonds with nitrogen contents generally higher than 500 ppm and nitrogen aggregation states of less than 40% IaB, and another, dominant population that is characterised by higher and more variable nitrogen aggregation. The unusually aggregated nature of the majority of the diamonds analysed is unique to Venetia relative to other intrusives on the Kaapvaal-Kalahari craton, but is similar to aggregation states observed for diamonds from other craton margin or adjacent mobile belt settings such as the Argyle lamproite and the George Creek kimberlite. This could be a consequence of diamond mantle residence at mantle temperatures higher than the norm for other kimberlites from the interior of cratons. Deformation of the mantle, associated with dynamic processes such as orogenesis or subduction, might also be responsible for accelerating the rate of nitrogen aggregation in these diamonds. Low numbers of diamonds with degradation of platelets at the Venetia kimberlite

  20. Extensional extrusion: Insights into south-eastward expansion of Tibetan Plateau from magnetotelluric array data

    Science.gov (United States)

    Dong, Hao; Wei, Wenbo; Jin, Sheng; Ye, Gaofeng; Zhang, Letian; Jing, Jian'en; Yin, Yaotian; Xie, Chengliang; Jones, Alan G.

    2016-11-01

    Despite extensive effort over many decades to understand the tectonic evolution of the Tibetan Plateau, the geodynamic processes creating the iconic south-eastward expansion of the plateau at the Eastern Himalayan Syntaxis (EHS) are still unclear and are hotly debated. Two popular (but not necessarily exclusive) geodynamic models, namely crustal flow at mid-to-lower crustal depths and coherent deformation between the crust and lithospheric mantle, are commonly invoked to explain the expansion mechanism. However, neither of these is able to reconcile all of the abundant geological and geophysical data. Here we present a three-dimensional (3D) geo-electrical model, derived from new SINOPROBE magnetotelluric (MT) array data, that reveals the geo-electrical, and by inference rheological, structure of southeast Tibet. Instead of NW-SE conductive channels proposed in prior two-dimensional (2D) MT studies, distinct NNE-SSW directed quasi-linear conductive anomalies are identified in the mid-to-lower crust, which are separated by a large-scale electrically resistive structure that extends from the crust to the upper mantle. This argues against the prior proposed model of south-eastward conductive anomalies, and hence against the southeast lower crust flow of material. To interpret our observations and resultant model, a new mechanism of "extensional extrusion" is proposed to address the lithospheric deformation of the south-eastward expansion of Tibetan Plateau.

  1. Tailoring properties of commercially pure titanium by gradation extrusion

    Science.gov (United States)

    Bergmann, Markus; Rautenstrauch, Anja; Selbmann, René; de Oliveira, Raoni Barreto; Coelho, Rodrigo Santiago; Landgrebe, Dirk

    2016-10-01

    Commercially pure titanium (CP Ti) is of great importance in medical applications due to its attractive properties, such as high biocompatibility, excellent corrosion resistance and relatively low density and suitable stiffness. Compared to the commonly used Ti-6Al-4V alloy, its lower strength has to be increased. The most attractive approach is to subject CP Ti to severe plastic deformation (SPD) processes such as Equal Channel Angular Pressing (ECAP). The resulting decreased grain size in CP Ti yields a significant increase in hardness and strength. Common SPD-processes typically provide a uniform modification of the material. Their material efficiency and productivity are critical and limiting factors. A new approach is to tailor the material properties by using Gradation Extrusion, which produces a distinct gradient in microstructure and strength. The forming process combines a regular impact extrusion process and severe plastic deformation in the lateral area of the material. This efficient process can be integrated easily into forming process chains, for instance for dental implants. This paper presents the forming process and the applied die geometry. The results of numerical simulations are used to illustrate the potential of the process to modify and strengthen the titanium material. Experiments show that the material is successfully processed by gradation extrusion. By characterizing the hardness and its distribution within the formed parts the effects of the process are investigated.

  2. Intrusion and extrusion of a liquid on nanostructured surfaces

    Science.gov (United States)

    Amabili, M.; Giacomello, A.; Meloni, S.; Casciola, C. M.

    2017-01-01

    Superhydrophobicity is connected to the presence of gas pockets within surface asperities. Upon increasing the pressure this ‘suspended’ state may collapse, causing the complete wetting of the rough surface. In order to quantitatively characterize this process on nanostructured surfaces, we perform rare-event atomistic simulations at different pressures and for several texture geometries. Such an approach allows us to identify for each pressure the stable and metastable states and the free energy barriers separating them. Results show that, by starting from the superhydrophobic state and increasing the pressure, the suspended state abruptly collapses at a critical intrusion pressure. If the pressure is subsequently decreased, the system remains trapped in the metastable state corresponding to the wet surface. The liquid can be extruded from the nanostructures only at very negative pressures, by reaching the critical extrusion pressure (spinodal for the confined liquid). The intrusion and extrusion curves form a hysteresis cycle determined by the large free energy barriers separating the suspended and wet states. These barriers, which grow very quickly for pressures departing from the intrusion/extrusion pressure, are shown to strongly depend on the texture geometry.

  3. Propulsion at low Reynolds number via beam extrusion

    Science.gov (United States)

    Gosselin, Frederick; Neetzow, Paul

    2014-03-01

    We present experimental and theoretical results on the extrusion of a slender beam in a viscous fluid. We are particularly interested in the force necessary to extrude the beam as it buckles with large amplitude due to viscous friction. The problem is inspired by the propulsion of Paramecium via trichocyst extrusion. Self-propulsion in micro-organisms is mostly achieved through the beating of flagella or cilia. However, to avoid a severe aggression, unicellular Paramecium has been observed to extrude trichocysts in the direction of the aggression to burst away. These trichocysts are rod-like organelles which, upon activation, grow to about 40 μm in length in 3 milliseconds before detaching from the animal. The drag force created by these extruding rods pushing against the viscous fluid generates thrust in the opposite direction. We developed an experimental setup to measure the force required to push a steel piano wire into an aquarium filled with corn syrup. This setup offers a near-zero Reynolds number, and allows studying deployments for a range of constant extrusion speeds. The experimental results are reproduced with a numerical model coupling a large amplitude Euler-Bernoulli beam theory with a fluid load model proportional to the local beam velocity. This study was funded in part by the The Natural Sciences and Engineering Research Council of Canada.

  4. Formation of chromosomal domains in interphase by loop extrusion

    Science.gov (United States)

    Fudenberg, Geoffrey

    While genomes are often considered as one-dimensional sequences, interphase chromosomes are organized in three dimensions with an essential role for regulating gene expression. Recent studies have shown that Topologically Associating Domains (TADs) are fundamental structural and functional building blocks of human interphase chromosomes. Despite observations that architectural proteins, including CTCF, demarcate and maintain the borders of TADs, the mechanisms underlying TAD formation remain unknown. Here we propose that loop extrusion underlies the formation TADs. In this process, cis-acting loop-extruding factors, likely cohesins, form progressively larger loops, but stall at TAD boundaries due to interactions with boundary proteins, including CTCF. This process dynamically forms loops of various sizes within but not between TADs. Using polymer simulations, we find that loop extrusion can produce TADs as determined by our analyses of the highest-resolution experimental data. Moreover, we find that loop extrusion can explain many diverse experimental observations, including: the preferential orientation of CTCF motifs and enrichments of architectural proteins at TAD boundaries; TAD boundary deletion experiments; and experiments with knockdown or depletion of CTCF, cohesin, and cohesin-loading factors. Together, the emerging picture from our work is that TADs are formed by rapidly associating, growing, and dissociating loops, presenting a clear framework for understanding interphase chromosomal organization.

  5. Hot-melt extrusion technology and pharmaceutical application.

    Science.gov (United States)

    Wilson, Matthew; Williams, Marcia A; Jones, David S; Andrews, Gavin P

    2012-06-01

    The use of hot-melt extrusion (HME) within the pharmaceutical industry is steadily increasing, due to its proven ability to efficiently manufacture novel products. The process has been utilized readily in the plastics industry for over a century and has been used to manufacture medical devices for several decades. The development of novel drugs with poor solubility and bioavailability brought the application of HME into the realm of drug-delivery systems. This has specifically been shown in the development of drug-delivery systems of both solid dosage forms and transdermal patches. HME involves the application of heat, pressure and agitation through an extrusion channel to mix materials together, and subsequently forcing them out through a die. Twin-screw extruders are most popular in solid dosage form development as it imparts both dispersive and distributive mixing. It blends materials while also imparting high shear to break-up particles and disperse them. HME extrusion has been shown to molecularly disperse poorly soluble drugs in a polymer carrier, increasing dissolution rates and bioavailability. The most common difficulty encountered in producing such dispersions is stabilization of amorphous drugs, which prevents them from recrystallization during storage. Pharmaceutical industrial suppliers, of both materials and equipment, have increased their development of equipment and chemicals for specific use with HME. Clearly, HME has been identified as an important and significant process to further enhance drug solubility and solid-dispersion production.

  6. Coherent Raman spectroscopy

    CERN Document Server

    Eesley, G L

    1981-01-01

    Coherent Raman Spectroscopy provides a unified and general account of the fundamental aspects of nonlinear Raman spectroscopy, also known as coherent Raman spectroscopy. The theoretical basis from which coherent Raman spectroscopy developed is described, along with its applications, utility, and implementation as well as advantages and disadvantages. Experimental data which typifies each technique is presented. This book is comprised of four chapters and opens with an overview of nonlinear optics and coherent Raman spectroscopy, followed by a discussion on nonlinear transfer function of matter

  7. Application Coherency Manager Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes an Application Coherency Manager that implements and manages the interdependencies of simulation, data, and platform information. It will...

  8. On -Coherent Endomorphism Rings

    Indian Academy of Sciences (India)

    Li-Xin Mao

    2008-11-01

    A ring is called right -coherent if every principal right ideal is finitely presented. Let $M_R$ be a right -module. We study the -coherence of the endomorphism ring of $M_R$. It is shown that is a right -coherent ring if and only if every endomorphism of $M_R$ has a pseudokernel in add $M_R; S$ is a left -coherent ring if and only if every endomorphism of $M_R$ has a pseudocokernel in add $M_R$. Some applications are given.

  9. The effects of post annealing on the mechanical properties, microstructure and texture evolutions of pure copper deformed by twist extrusion process

    Energy Technology Data Exchange (ETDEWEB)

    Akbari Mousavi, S.A.A., E-mail: akbarimusavi@ut.ac.ir [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, North Kargar Street, P.O. Box: 11155-4563, Tehran (Iran, Islamic Republic of); Bahadori, Sh. Ranjbar [School of Metallurgy and Materials Engineering, University College of Engineering, University of Tehran, North Kargar Street, P.O. Box: 11155-4563, Tehran (Iran, Islamic Republic of)

    2011-01-25

    Research highlights: {yields} Post annealing solve the softening problem occurred in repeated passes of TE. {yields} Post annealing decreased the coherent domain size of twist extruded sample. {yields} Post annealing increased the microstrain of twist extruded sample. {yields} Simple shear mode is the mechanism of deformation across the TE sample. {yields} The simple shear mechanism is disrupted by post annealing treatments. - Abstract: X-ray diffraction peak broadening analysis showed that performing a proper heat treatment between the twist extrusion passes of commercially pure copper decreased the coherent domain size and increased the microstrain. Moreover, SEM micrographs illustrated that annealed material contained new formed grains that could not grow due to lack of sufficient time. Under such circumstances, the ultimate strength was elevated about 45 MPa. The deformed material showed texture of simple shear deformation, changing by applying the post annealing.

  10. Influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Ling; TIAN Su-gui; MENG Fan-lai; DU Hong-qiang

    2006-01-01

    Extrusion treatment is a common method to refine the grain size and improve the mechanical properties of metal material. The influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy was investigated. The results show that the mechanical properties of AZ31 alloy are obviously improved by extrusion treatment. The ultimate tensile strength (UTS) of AZ31 alloy at room temperature is measured to be 222 MPa, and is enhanced to 265.8 MPa after extrusion at 420℃. The yield tensile strength (YTS) of AZ31 alloy at room temperature is measured to be 84 MPa, and is enhanced to 201 MPa after extrusion at 420℃. The effective improvements on mechanical properties result from the formation of the finer grains during extrusion and the finer particles precipitated by age treatment. The features of the microstructure evolution during hot extruded of AZ31 alloy are dislocation slipping on the matrix and occurrence of the dynamic recrystallization.

  11. Temperature window effect and its application in extrusion of ultrahigh molecular weight polyethylene

    Directory of Open Access Journals (Sweden)

    2011-08-01

    Full Text Available Ultrahigh molecular weight polyethylene (UHMWPE was ram extruded using a temperature window effect. The extrusion pressure abruptly drops at a very narrow extrusion temperature window which is about 10°C higher than the theoretical melting point of orthorhombic polyethylene crystals under quiescent and equilibrium states. The correlation between extrusion pressure and parameters such as extrusion temperature, annealing condition, thermal history, piston velocity, L/D ratio of the die, and molecular weight of UHMWPE, was studied. The temperature window increases with molecular weight and is unaffected by thermal history and annealing. The stable extrusion pressure and the critical piston velocity decrease with the rise in the extrusion temperature. The flow resistance reversely depends on the L/D ratio of the die. This phenomenon is attributed to an extensional flow-induced chain alignment along the streamline, which results in the formation of a metastable mesophase with higher chain mobility.

  12. Text Coherence in Translation

    Science.gov (United States)

    Zheng, Yanping

    2009-01-01

    In the thesis a coherent text is defined as a continuity of senses of the outcome of combining concepts and relations into a network composed of knowledge space centered around main topics. And the author maintains that in order to obtain the coherence of a target language text from a source text during the process of translation, a translator can…

  13. Reverse Coherent Information

    Science.gov (United States)

    García-Patrón, Raúl; Pirandola, Stefano; Lloyd, Seth; Shapiro, Jeffrey H.

    2009-05-01

    In this Letter we define a family of entanglement distribution protocols assisted by feedback classical communication that gives an operational interpretation to reverse coherent information, i.e., the symmetric counterpart of the well-known coherent information. This leads to the definition of a new entanglement distribution capacity that exceeds the unassisted capacity for some interesting channels.

  14. Understanding Causal Coherence Relations

    NARCIS (Netherlands)

    Mulder, G.

    2008-01-01

    The research reported in this dissertation focuses on the cognitive processes and representations involved in understanding causal coherence relations in text. Coherence relations are the meaning relations between the information units in the text, such as Cause-Consequence. These relations can be m

  15. VCSELs for coherent PON

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Rodes, Roberto; Cheng, Ning;

    2015-01-01

    Recent advances and research on coherent technologies for access networks are discussed and put into context of user demands and standardization work.......Recent advances and research on coherent technologies for access networks are discussed and put into context of user demands and standardization work....

  16. VCSEL Based Coherent PONs

    DEFF Research Database (Denmark)

    Jensen, Jesper Bevensee; Rodes, Roberto; Caballero Jambrina, Antonio;

    2014-01-01

    We present a review of research performed in the area of coherent access technologies employing vertical cavity surface emitting lasers (VCSELs). Experimental demonstrations of optical transmission over a passive fiber link with coherent detection using VCSEL local oscillators and directly modula...

  17. NUMERICAL SIMULATION OF EXTRUSION OF COMPOSITE POWDERS PREPARED BY HIGH ENERGY MILLING

    Institute of Scientific and Technical Information of China (English)

    X.Q. Li; W.P. Chen; W. Xia; Q.L. Zhu; Y.Y. Li; E.D. Wang

    2004-01-01

    Based on the characteristic of high energy milling and the micromechanics of composite material, a plastic constitutive equation is implemented for milled composite powders. To check the equation, the extrusion of Ti/Al composite powders prepared by high energy milling was simulated. It was from the numerical analysis that the predicted extrusion pressure mounted up with milling time and extrusion ratio increasing,which was perfect agreement with experimental results.

  18. Partially coherent ultrafast spectrography.

    Science.gov (United States)

    Bourassin-Bouchet, C; Couprie, M-E

    2015-03-06

    Modern ultrafast metrology relies on the postulate that the pulse to be measured is fully coherent, that is, that it can be completely described by its spectrum and spectral phase. However, synthesizing fully coherent pulses is not always possible in practice, especially in the domain of emerging ultrashort X-ray sources where temporal metrology is strongly needed. Here we demonstrate how frequency-resolved optical gating (FROG), the first and one of the most widespread techniques for pulse characterization, can be adapted to measure partially coherent pulses even down to the attosecond timescale. No modification of experimental apparatuses is required; only the processing of the measurement changes. To do so, we take our inspiration from other branches of physics where partial coherence is routinely dealt with, such as quantum optics and coherent diffractive imaging. This will have important and immediate applications, such as enabling the measurement of X-ray free-electron laser pulses despite timing jitter.

  19. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    Science.gov (United States)

    de Jesus, Marcelo Bispo; Radaic, Allan; Zuhorn, Inge S.; de Paula, Eneida

    2013-10-01

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles' in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis).

  20. Microemulsion extrusion technique: a new method to produce lipid nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jesus, Marcelo Bispo de, E-mail: dejesusmb@gmail.com; Radaic, Allan [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil); Zuhorn, Inge S. [University of Groningen, Department of Membrane Cell Biology, University Medical Center (Netherlands); Paula, Eneida de [University of Campinas-UNICAMP, Department of Biochemistry, Institute of Biology (Brazil)

    2013-10-15

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been intensively investigated for different applications, including their use as drug and gene delivery systems. Different techniques have been employed to produce lipid nanoparticles, of which high pressure homogenization is the standard technique that is adopted nowadays. Although this method has a high efficiency, does not require the use of organic solvents, and allows large-scale production, some limitations impede its application at laboratory scale: the equipment is expensive, there is a need of huge amounts of surfactants and co-surfactants during the preparation, and the operating conditions are energy intensive. Here, we present the microemulsion extrusion technique as an alternative method to prepare lipid nanoparticles. The parameters to produce lipid nanoparticles using microemulsion extrusion were established, and the lipid particles produced (SLN, NLC, and liposomes) were characterized with regard to size (from 130 to 190 nm), zeta potential, and drug (mitoxantrone) and gene (pDNA) delivery properties. In addition, the particles' in vitro co-delivery capacity (to carry mitoxantrone plus pDNA encoding the phosphatase and tensin homologue, PTEN) was tested in normal (BALB 3T3 fibroblast) and cancer (PC3 prostate and MCF-7 breast) cell lines. The results show that the microemulsion extrusion technique is fast, inexpensive, reproducible, free of organic solvents, and suitable for small volume preparations of lipid nanoparticles. Its application is particularly interesting when using rare and/or costly drugs or ingredients (e.g., cationic lipids for gene delivery or labeled lipids for nanoparticle tracking/diagnosis)

  1. Distal corporoplasty for distal cylinders extrusion after penile prosthesis implantation.

    Science.gov (United States)

    Carrino, Maurizio; Chiancone, Francesco; Battaglia, Gaetano; Pucci, Luigi; Fedelini, Paolo

    2017-02-03

    Distal extrusion of cylinders is a potential complication of the penile prosthesis implantation. Several methods have been proposed for repairing a distal penile erosion. We present our preliminary experience in "Distal corporoplasty" technique. We enrolled 18 consecutive patients whose underwent a distal corporoplasty with simultaneous reimplantation of an "AMS 700 inflatable penile prosthesis (LGX)" from January 2013 to November 2015 at our hospital. All procedures were performed by a single surgical team. Intraoperative and postoperative complications have been classified and reported according to Satava6 and Clavien-Dindo (CD) system.7 Mean values with standard deviations (±SD) were computed and reported for all items. Mean age of the patients was 53.61 (±11.90) years. Mean body max index (BMI) was 24.22 (±2.51). Mean operative time was 85.2 (±13.1) minutes. Blood losses were minimal. No intraoperative complications are reported according to Satava classification. Four out of 18 patients (22.22%) experienced postoperative complications according to CD system. All patients had sexual intercourse for the first time postsurgery after a mean of 59.11 ± 2.08 days. Mean follow-up was 22.11 (±9.95). Distal extrusion of cylinders is a potential complication of the penile prosthesis implantation. Distal corporoplasty was first described by Mulcahy. He reported a series of 14 patients with a follow-up of about 2 years with optimal functional outcomes. Moreover, distal corporoplasty resulted in shorter operative time, better function, less pain, and fewer recurrences than Gortex windsock repair.10 In our experience, distal corporoplasty is a simple and safe procedure in the treatment of distal cylinders extrusion when the prosthetic material is not exposed to the exterior.

  2. Role of lipids in the extrusion cooking processes

    Directory of Open Access Journals (Sweden)

    Berghofe, E.

    2000-04-01

    Full Text Available Extrusion is a versatile and very efficient technology that is widely used in food and feed processing. The cooking extruders have found many applications, which include: breakfast cereals, snack foods, other cereal based products, pet food and aquatic foods, texturized vegetable proteins, confectionery products, chemical and biochemical reactions, and oil extraction. Lipids are components that play an important role in most of the extrusion cooking processes. They can act as plastificizers or emulsifiers, and affect more significantly texture and stickiness of the extrudate. This paper reviews effect of oils and other lipids reactions during extrusion cooking as well as the effects of amylase-lipid complexation on extrudate quality.La extrusión es, en general, una tecnología versátil y muy eficiente, que se aplica ampliamente en la elaboración de alimentos y piensos. Los equipos de cocción-extrusión tienen numerosas aplicaciones, entre las que pueden incluirse: los cereales de desayuno listos para comer, los aperitivos, diferentes productos basados en cereales, los piensos para animales domésticos y peces, proteínas vegetales texturizadas, productos de pastelería, reacciones químicas y bioquímicas, y la extracción de aceites. Los lípidos son componentes que juegan un papel importante en la mayoría de los procesos de cocción-extrusión. Pueden actuar como plastificantes o como emulsionantes, suministrando lubricación. En este artículo se revisan con detalle los efectos de las reacciones de los aceites y otros lípidos durante el proceso de cocción-extrucción así como el efecto de la formación de complejos amilasa-lípidos sobre la calidad de los extrudados.

  3. Evolution of diamond resorption in a silicic aqueous fluid at 1-3 GPa: Application to kimberlite emplacement and mantle metasomatism

    Science.gov (United States)

    Zhang, Zhihai; Fedortchouk, Yana; Hanley, Jacob J.

    2015-06-01

    Natural diamonds grow and partially dissolve during mantle metasomatism and undergo further resorption during the ascent to the Earth's surface in kimberlite magmas. This study uses atomic force microscopy (AFM) for quantitative characterization of diamond resorption morphology in order to provide robust constraints of the composition of kimberlitic and mantle metasomatic fluids. We performed experiments in a piston-cylinder apparatus at pressures (P) of 1-3 GPa and temperatures (T) of 1150-1400 °C to examine the impact of P, T, and silica content of an aqueous fluid on diamond dissolution. Petrographic observation and microthermometry of synthetic fluid inclusions trapped in olivine at the run conditions provide constraints on the composition and density of the fluid reacting with the diamond. Our results confirm an inverse relationship between P and T on diamond dissolution kinetics. A P increase of 1 GPa suppresses diamond oxidation rates by the same value as a T decrease by 50 °C, while the transformation rate of diamond crystal morphology from octahedron to tetrahexahedron increases with both P and T. All dissolved diamonds develop glossy surfaces, ditrigonal {111} faces, sheaf striations, and negative trigons, while circular pits only occur in aqueous fluids with low silica content (≤ 4.2 mol/kg) at 1 GPa. We identify five distinct morphological groups of trigons: two types of point-bottomed (p/b) (trumpet- and V-shaped) and three types of flat-bottomed (f/b) (trumpet-shaped, trapezoid-shaped and rounded). AFM measurements of trigons from two successive runs showed three stages of their evolution. Etch pits nucleate at defects as trumpet p/b trigons with the vertical dissolution rate (Vd) faster than the dissolution rates at the surface free of defects; they further develop by growth of the bottoms in (111) plane to create trumpet-shaped f/b trigons accompanied by decrease in Vd; and finally form trapezoid-shaped f/b trigon with constant wall angles. The

  4. Adaptive Control of Freeze-Form Extrusion Fabrication Processes (Preprint)

    Science.gov (United States)

    2008-05-01

    speed of 127 mm/s and a resolution of 2.54 µm. The axes are controlled by a Delta–Tau Turbo PMAC (Programmable Multi–Axis Controller) PCI board. The...digital conversion board (Delta–Tau ACC28) with a voltage range of ±5 V converts the analog signal from the load cell into a digital signal in the PMAC ...controllers on the PMAC control board. Estimation and control algorithms for the extrusion mechanism are implemented in PLC programs, which are also

  5. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten;

    2016-01-01

    of coherence in treatment and patient pathways. The aim of our study is to explore the role of health care providers in furthering coherence. Our ambition is to identify areas for improvement or change of collaborative practice between health care providers in municipalities, hospitals and general practice...... initiatives in health care. The present study will generate new, valuable insight into the areas of cross-sectorial health care collaboration. Our findings may facilitate change in current practice and improve the quality and coherence in patient pathways of EPCD. The findings of this study will be useful...

  6. Coherent diffractive {rho} production

    Energy Technology Data Exchange (ETDEWEB)

    Hyett, N.M.; Tovey, S.N. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1995-12-31

    Coherent diffractive {rho} production by neutrinos occurs at low four-momentum transfer and high energy transfer. These interactions are generally understood to occur via the coupling of the weak charged current to the vector meson, which scatters diffractively from the target nucleus. Since coherent events are those in which the nucleus interacts as a whole, ie without breakup, and with small recoil energy, these events have a very sharp |t|-distribution. This presentation deals mostly with the Monte Carlo simulation of the coherent diffractive production of the {rho} production and in particular with the reconstruction algorithm (description and efficiency) and the |t| distribution. 4 refs., 1 fig.

  7. The Coherent Curriculum

    Institute of Scientific and Technical Information of China (English)

    Michael Thomas

    2005-01-01

    @@ What makes a coherent EFL curriculum? How can curriculum planners avoid a mismatch between policy and pragmatics to produce an effective decision-making process? In The Second Language Curriculum, Johnson describes the coherent curriculum as one in which decision outcomes from the various stages of development are mutually consistent and complementary,and learning outcomes reflect curriculum aims.The achievement of coherence is said to depend crucially in most educational contexts upon the formalisation of decision-making processes and products. This formalisation facilitates consensus among those involved and is a prerequisite for effective evaluation and subsequent renewal (1994: xiii)

  8. Investigation on Effects of Die Orifice Layout on Three-Hole Porthole Extrusion of Aluminum Alloy 6063 Tubes

    Science.gov (United States)

    Zhang, Cunsheng; Zhao, Guoqun; Chen, Hao; Guan, Yanjin; Cai, Haijin; Gao, Baojie

    2013-05-01

    Currently, with the increasing demand of high production output, much attention is paid to the research and development of multi-hole extrusion die. However, owing to the complexity of multi-hole porthole extrusion technology, it has not been applied widely in practice for the production of aluminum profiles, especially for porthole die with an odd number of die orifices. The purpose of this study is to design a three-hole porthole die for producing an aluminum tube and to optimize the location of die orifices based on computer-aided design and engineering. First, three-hole extrusion dies for different locations of die orifices are designed. Then, extrusion processes with different multi-hole porthole dies are simulated by means of HyperXtrude. Through numerical simulation, metal flow, temperature distribution, welding pressure, extrusion load, and die stress, etc. could be obtained, and the effects of the location of die orifices on extrusion process are investigated. With the increasing distance between die orifice and extrusion center (described as eccentricity ratio), metal flow becomes nonhomogeneous, and twisting or bending deformation of profile occurs, but the welding pressure rises, which improves the welding quality of profiles. However, the required extrusion force, billet and die temperature, die displacement, and stress induce no significant changes. In comparison with the extrusion force during single-hole porthole extrusion, there is 18.5% decrease of extrusion force during three-hole porthole extrusion. Finally, design rules for this kind of multi-hole extrusion dies are summarized.

  9. Origin of sub-lithospheric diamonds from the Juina-5 kimberlite (Brazil): constraints from carbon isotopes and inclusion compositions

    Science.gov (United States)

    Thomson, A. R.; Kohn, S. C.; Bulanova, G. P.; Smith, C. B.; Araujo, D.; Walter, M. J.

    2014-12-01

    Forty-one diamonds sourced from the Juina-5 kimberlite pipe in Southern Brazil, which contain optically identifiable inclusions, have been studied using an integrated approach. The diamonds contain <20 ppm nitrogen (N) that is fully aggregated as B centres. Internal structures in several diamonds revealed using cathodoluminescence (CL) are unlike those normally observed in lithospheric samples. The majority of the diamonds are composed of isotopically light carbon, and the collection has a unimodal distribution heavily skewed towards δ13C ~ -25 ‰. Individual diamonds can display large carbon isotope heterogeneity of up to ~15 ‰ and predominantly have isotopically lighter cores displaying blue CL, and heavier rims with green CL. The light carbon isotopic compositions are interpreted as evidence of diamond growth from abiotic organic carbon added to the oceanic crust during hydrothermal alteration. The bulk isotopic composition of the oceanic crust, carbonates plus organics, is equal to the composition of mantle carbon (-5 ‰), and we suggest that recycling/mixing of subducted material will replenish this reservoir over geological time. Several exposed, syngenetic inclusions have bulk compositions consistent with former eclogitic magnesium silicate perovskite, calcium silicate perovskite and NAL or CF phases that have re-equilibrated during their exhumation to the surface. There are multiple occurrences of majoritic garnet with pyroxene exsolution, coesite with and without kyanite exsolution, clinopyroxene, Fe or Fe-carbide and sulphide minerals alongside single occurrences of olivine and ferropericlase. As a group, the inclusions have eclogitic affinity and provide evidence for diamond formation at pressures extending to Earth's deep transition zone and possibly the lower mantle. It is observed that the major element composition of inclusions and isotopic compositions of host Juina-5 diamonds are not correlated. The diamond and inclusion compositions are

  10. The evolution of the lithosphere in southern Africa: A perspective on the basic granulite xenoliths from kimberlites in South Africa

    Science.gov (United States)

    Huang, Yi-Ming; Van Calsteren, Peter; Hawkesworth, Chris I.

    1995-12-01

    Major, trace element, and strontium, neodymium, and lead isotope data are presented on mafic granulite xenoliths from the margins of the Kaapvaal Craton in southern Africa. Those from the Markt pipe in the central Cape province preserve good correlations between Cr and Mg#, negative correlations between Co, Sc, Y, and V with Al 2O 3, and positive correlations between Sr, Rb/Sr, and Eu/Eu ∗ with Al 2O 3 Such trends reflect magmatic differentiation and crystal cumulation, and they have not been affected significantly by subsequent metamorphism. Present-day strontium and neodymium isotope ratios range from 0.70411-0.71179 and from 0.51149-0.51294. The lead isotope data from the Markt granulites yield a bulk rock PbPb age of 3.19 ± 0.07 Ga and those from the other Cape province granulites have similar lead isotope ages (3.2 ˜ 3.4 Ga). These ages are supported by two PbPb mineral-whole ages of ˜2.9 Ga, indicating their Archaean origin, even though both SmNd whole rock and mineral errorchrons yield Proterozoic ages. A PbPb errorchron for the granulites from northern Lesotho yields an age of 1.49 ± 0.36 which is indistinguishable from their SmNd errorchron age of 1.24 ± 0.17 Ga. Thus, it is inferred that the granulite xenoliths from northern Lesotho are from Proterozoic lower crust, whereas the granulite xenoliths from the central Cape province are from Archaean lower crust. Most lead isotope data from the granulite xenoliths plot to the left of the Geochron and indicate relatively low U/Pb ratios. Lead isotope ratios in the granulites from Markt correlate with A1 2O 3, and such correlations are considered to be largely due to magmatic processes. The lead isotope trends displayed by the Archaean granulite xenoliths represent μ ( 238U /204Pb ) fractionation during extraction of the Archaean crust from the mantle, as do those preserved in greenstone belt rocks from the southern Kaapvaal Craton. Group 2 kimberlites, mantle xenoliths from Kimberley, and

  11. Coherence in Industrial Transformation

    DEFF Research Database (Denmark)

    Jørgensen, Ulrik; Lauridsen, Erik Hagelskjær

    2003-01-01

    The notion of coherence is used to illustrate the general finding, that the impact of environmental management systems and environmental policy is highly dependent of the context and interrelatedness of the systems, procedures and regimes established in society....

  12. Coherence for Modalities

    CERN Document Server

    Dosen, K

    2008-01-01

    Positive modalities in systems in the vicinity of S4 and S5 are investigated in terms of categorial proof theory. Coherence and maximality results are demonstrated, and connections with mixed distributive laws and Frobenius algebras are exhibited.

  13. Coherence in Industrial Transformation

    DEFF Research Database (Denmark)

    Jørgensen, Ulrik; Lauridsen, Erik Hagelskjær

    2003-01-01

    The notion of coherence is used to illustrate the general finding, that the impact of environmental management systems and environmental policy is highly dependent of the context and interrelatedness of the systems, procedures and regimes established in society....

  14. Genuine Quantum Coherence

    CERN Document Server

    Streltsov, Alexander

    2015-01-01

    The basis of any quantum resource theory are free states and free operations, these are states and operations which can be created or performed at no cost. In the resource theory of quantum coherence free states are states which are diagonal in a fixed reference basis. This choice is natural in many experimental scenarios where the reference basis is singled out by the unavoidable decoherence. The corresponding free operations are called incoherent, they can be implemented as a generalized measurement which does not create any coherence. However, a general quantum operation admits different experimental realizations, and a quantum operation which seems incoherent in one experimental realization might create coherence in another. Starting from this observation, we propose the framework of genuine quantum coherence. This approach is based on a simple principle: we demand that a genuinely incoherent operation preserves all incoherent states. This simple condition automatically guarantees that the operation is in...

  15. Partially coherent sources with circular coherence: comment.

    Science.gov (United States)

    Hyde, Milo W; Bose-Pillai, Santasri R

    2017-08-15

    In [Opt. Lett.42, 1512 (2017)OPLEDP0146-959210.1364/OL.42.001512], the authors present a new class of non-uniformly correlated sources with circular coherence. They also describe a basic experimental setup for synthesizing this class of sources, which uses the Van Cittert-Zernike theorem. Here, we present an alternative way to analyze these sources and a different way to generate them.

  16. Coherence-Enhanced Spaser

    CERN Document Server

    Dorfman, Konstantin E; Voronine, Dmitri V; Genevet, Patrice; Capasso, Federico; Scully, Marlan O

    2012-01-01

    We investigate surface plasmon amplification in a silver nanoshell coupled to an externally driven three-level gain medium, and show that quantum coherence significantly enhances the generation of surface plasmons. Surface plasmon amplification by stimulated emission of radiation is achieved in the absence of population inversion on the spasing transition, which reduces the pump requirements. The coherent drive allows us to control the dynamics, and holds promise for quantum control of nanoplasmonic devices.

  17. Optical Coherency Matrix Tomography

    Science.gov (United States)

    2015-10-19

    optics has been studied theoretically11, but has not been demonstrated experimentally heretofore. Even in the simplest case of two binary DoFs6 (e.g...coherency matrix G spanning these DoFs. This optical coherency matrix has not been measured in its entirety to date—even in the simplest case of two...dense coding, etc. CREOL, The College of Optics & Photonics, University of Central Florida, Orlando , Florida 32816, USA. Correspondence and requests

  18. Histopathology of explanted AlphaCor due to keratoprosthesis extrusion.

    Science.gov (United States)

    Caporossi, Aldo; Mazzotta, Cosimo; Balestrazzi, Angelo; Occhini, Rossella; Toti, Paolo; Traversi, Claudio

    2006-07-01

    AlphaCor keratoprosthesis (KPro) is a new-concept poly (2-hydroxyethyl methacrylate) one-piece KPro that makes possible a two-step implantation technique easy to perform with a short learning curve. In literature an 18% incidence of AlphaCor removal due to melting complications is reported. The histopathology of corneal tissue removed during a re-operation while bearing an AlphaCor KPro has previously been described in the literature only in one report. Herein, the first histological features of an AlphaCor-corneal complex explanted because of KPro extrusion is described. The histopathology of the AlphaCor-corneal complex is characterized by mild inflammation in the corneal tissues, limited to the region surrounding the anteriorized and extruded part of the KPro. It is not possible to fully understand the mechanisms that trigger the device extrusion. One possible explanation could be a dislocation of the prosthesis in the corneal pocket due to the untied fixation stitch. Another explanation could be a foreign body reaction induced by KPro.

  19. Continuous manufacturing of solid lipid nanoparticles by hot melt extrusion.

    Science.gov (United States)

    Patil, Hemlata; Kulkarni, Vijay; Majumdar, Soumyajit; Repka, Michael A

    2014-08-25

    Solid lipid nanoparticles (SLN) can either be produced by hot homogenization of melted lipids at higher temperatures or by a cold homogenization process. This paper proposes and demonstrates the formulation of SLN for pharmaceutical applications by combining two processes: hot melt extrusion (HME) technology for melt-emulsification and high-pressure homogenization (HPH) for size reduction. This work aimed at developing continuous and scalable processes for SLN by mixing a lipid and aqueous phase containing an emulsifier in the extruder barrel at temperatures above the melting point of the lipid and further reducing the particle size of emulsion by HPH linked to HME in a sequence. The developed novel platform demonstrated better process control and size reduction compared to the conventional process of hot homogenization (batch process). Varying the process parameters enabled the production of SLN below 200 nm (for 60 mg/ml lipid solution at a flow rate of 100ml/min). Among the several process parameters investigated, the lipid concentration, residence time and screw design played major roles in influencing the size of the SLN. This new process demonstrates the potential use of hot melt extrusion technology for continuous and large-scale production of SLN.

  20. Numerical simulation of burst defects in cold extrusion process

    Science.gov (United States)

    Labergère, C.; Lestriez, P.; Saanouni, K.

    2007-05-01

    The formation of the central bursts in axisymmetric cold extrusion is numerically simulated by using 2D finite element analysis (FEA) accounting for the mixed isotropic and kinematic hardening together with the ductile damage effect. The coupling between the ductile damage and the elastoplastic constitutive equations is formulated in the framework of the thermodynamics of irreversible processes together with the Continuum Damage Mechanics (CDM) theory. An isotropic ductile damage model is fully coupled with elastoplastic constitutive equations including non linear isotropic and kinematic hardening. A modified ductile damage criterion based on linear combination of the stress tensor invariants is used in order to predict the occurrence of micro-crack initiation as a discontinuous central bursts along the bar axis. The implicit integration scheme of the fully coupled constitutive equations and the Dynamic Explicit resolution scheme to solve the associated initial and boundary value problem are outlined. Application is made to the prediction of the chevron shaped cracks in cold extrusion of a round bar. The effect of various process parameters, as the diameter reduction ratio, the die semi-angle, the friction coefficient and the material ductility, on the central bursts occurrence are discussed.

  1. Optimization of extrusion process for production of nutritious pellets

    Directory of Open Access Journals (Sweden)

    Ernesto Aguilar-Palazuelos

    2012-03-01

    Full Text Available A blend of 50% Potato Starch (PS, 35% Quality Protein Maize (QPM, and 15% Soybean Meal (SM were used in the preparation of expanded pellets utilizing a laboratory extruder with a 1.5 × 20.0 × 100.0 mm die-nozzle. The independent variables analyzed were Barrel Temperature (BT (75-140 °C and Feed Moisture (FM (16-30%. The effect of extrusion variables was investigated in terms of Expansion Index (EI, apparent density (ApD, Penetration Force (PF and Specific Mechanical Energy (SME, viscosity profiles, DSC, crystallinity by X-ray diffraction, and Scanning Electronic Microscopy (SEM. The PF decreased from 30 to 4 kgf with the increase of both independent variables (BT and FM. SME was affected only by FM, and decreased with the increase in this variable. The optimal region showed that the maximum EI was found for BT in the range of 123-140 °C and 27-31% for FM, respectively. The extruded pellets obtained from the optimal processing region were probably not completely degraded, as shown in the structural characterization. Acceptable expanded pellets could be produced using a blend of PS, QPM, and SM by extrusion cooking.

  2. Revascularization of immature permanent incisors after severe extrusive luxation injury.

    Science.gov (United States)

    Cehreli, Zafer C; Sara, Sezgi; Aksoy, Burak

    2012-07-01

    Pulp necrosis is an uncommon sequel to extrusive luxation in immature teeth with incomplete apical closure. In this report, we describe the management of severely extruded immature maxillary incisors and the outcome of revascularization to treat subsequent pulp necrosis. An 8.5-year-old boy with severe dentoalveolar trauma to the anterior maxillary region as a result of a fall was provided emergency treatment consisting of reduction of the dislodged labial cortical bone and repositioning of the central incisors, which had suffered extrusive luxation. When he presented with spontaneous pain involving the traumatized incisors a week later, the teeth were treated via a revascularization protocol using sodium hypochlorite irrigation followed by 3 weeks of intracanal calcium hydroxide, then a coronal seal of mineral trioxide aggregate and resin composite. Complete periradicular healing was observed after 3 months, followed by progressive thickening of the root walls and apical closure. Follow-up observations confirmed the efficacy of the regenerative treatment as a viable alternative to conventional apexification in endodontically involved, traumatized immature teeth.

  3. Solid lipid extrusion of sustained release dosage forms.

    Science.gov (United States)

    Reitz, Claudia; Kleinebudde, Peter

    2007-09-01

    The applicability of the solid lipid extrusion process as preparations method for sustained release dosage forms was investigated in this study. Two lipids with similar melting ranges but of different composition, glyceryl palmitostearate (Precirol ATO 5) and glyceryl trimyristate (Dynasan 114), and mixtures of each lipid with 50% or 75% theophylline were extruded at temperatures below their melting ranges. Extrudates were analyzed using differential scanning calorimetry, scanning electron microscopy, porosity measurements and in vitro drug dissolution studies. The possibility of processing lipids by softening instead of complete melting and without subsequent formation of low-melting, metastable polymorphs could be demonstrated. Extrudates based on formulations of glyceryl palmitostearate/theophylline (50:50) and glyceryl trimyristate/theophylline (50:50) showed sustained release properties. An influence of extrusion conditions on the matrix structure was shown for extrudates based on a mixture of glyceryl trimyristate and theophylline (50:50). Glyceryl trimyristate tended to solidify in porous structures after melting. Exceeding a material temperature of 50.5 degrees C led to porous extrudate matrices with a faster drug release. The production of novel, non porous sustained release matrices was possible at a material temperature of 49.5 degrees C. Extrudates based on glyceryl trimyristate/theophylline (50:50) only slight changes in melting enthalpy and stable drug release profiles.

  4. Phenomenological model of maize starches expansion by extrusion

    Science.gov (United States)

    Kristiawan, M.; Della Valle, G.; Kansou, K.; Ndiaye, A.; Vergnes, B.

    2016-10-01

    During extrusion of starchy products, the molten material is forced through a die so that the sudden abrupt pressure drop causes part of the water to vaporize giving an expanded, cellular structure. The objective of this work was to elaborate a phenomenological model of expansion and couple it with Ludovic® mechanistic model of twin screw extrusion process. From experimental results that cover a wide range of thermomechanical conditions, a concept map of influence relationships between input and output variables was built. It took into account the phenomena of bubbles nucleation, growth, coalescence, shrinkage and setting, in a viscoelastic medium. The input variables were the moisture content MC, melt temperature T, specific mechanical energy SME, shear viscosity η at the die exit, computed by Ludovic®, and the melt storage moduli E'(at T > Tg). The outputs of the model were the macrostructure (volumetric expansion index VEI, anisotropy) and cellular structure (fineness F) of solid foams. Then a general model was established: VEI = α (η/η0)n in which α and n depend on T, MC, SME and E' and the link between anisotropy and fineness was established.

  5. Extrusion foaming of protein-based thermoplastic and polyethylene blends

    Science.gov (United States)

    Gavin, Chanelle; Lay, Mark C.; Verbeek, Casparus J. R.

    2016-03-01

    Currently the extrusion foamability of Novatein® Thermoplastic Protein (NTP) is being investigated at the University of Waikato in collaboration with the Biopolymer Network Ltd (NZ). NTP has been developed from bloodmeal (>86 wt% protein), a co-product of the meat industry, by adding denaturants and plasticisers (tri-ethylene glycol and water) allowing it to be extruded and injection moulded. NTP alone does not readily foam when sodium bicarbonate is used as a chemical blowing agent as its extensional viscosity is too high. The thermoplastic properties of NTP were modified by blending it with different weight fractions of linear low density polyethylene (LLDPE) and polyethylene grafted maleic anhydride (PE-g-MAH) compatibiliser. Extrusion foaming was conducted in two ways, firstly using the existing water content in the material as the blowing agent and secondly by adding sodium bicarbonate. When processed in a twin screw extruder (L/D 25 and 10 mm die) the material readily expanded due to the internal moisture content alone, with a conditioned expansion ratio of up to ± 0.13. Cell structure was non-uniform exhibiting a broad range cell sizes at various stages of formation with some coalescence. The cell size reduced through the addition of sodium bicarbonate, overall more cells were observed and the structure was more uniform, however ruptured cells were also visible on the extrudate skin. Increasing die temperature and introducing water cooling reduced cell size, but the increased die temperature resulted in surface degradation.

  6. Propulsion via beam extrusion at low Reynolds number

    CERN Document Server

    Gosselin, Frederick P; Paak, Mehdi

    2014-01-01

    Inspired by microscopic paramecies which use trichocyst extrusion to propel themselves away from thermal aggressions, we propose a macroscopic experiment to study the stability of a slender beam extruded in a highly viscous fluid. Piano wires were extruded axially at constant speed in a tank filled with corn syrup. The force necessary to extrude the wire was measured to increase linearly at first until the compressive viscous force causes the wire to buckle. A numerical model, coupling a lengthening elastica formulation with resistive force theory, predicts a similar behaviour. The model is used to study the dynamics at large time when the beam is highly deformed. It is found that at large time, a large deformation regime exists in which the force necessary to extrude the beam at constant speed becomes constant and length-independent. With a proper dimensional analysis, the beam can be shown to buckle at a critical length based on the extrusion speed, the bending rigidity and the dynamic viscosity of the flui...

  7. 78 FR 51143 - Aluminum Extrusions From the People's Republic of China: Initiation of Changed Circumstances...

    Science.gov (United States)

    2013-08-20

    ..., including, but not limited to, window frames, door frames, solar panels, curtain walls, or furniture. Such... backing material, and solar panels. The scope also excludes finished goods containing aluminum extrusions... Aluminum Extrusions from the People's Republic of China: Antidumping Duty Order, 76 FR 30650 (May 26,...

  8. Chemical, physical and nutritional changes in soybean meal as a result of toasting and extrusion cooking.

    NARCIS (Netherlands)

    Marsman, G.J.P.

    1998-01-01

    The effect of soybean meal extrusion and the development of shear forces during single-screw extrusion was compared with the toasting process of soybean meal. Attention was focused on chemical, physical and nutritional changes during these thermo-mechanical treatments.Monitoring target parameters we

  9. Way of Producing Porous-Free Long-Measured Blanks of Hot Extrusion

    Directory of Open Access Journals (Sweden)

    G.H. Tumanyan

    2007-09-01

    Full Text Available The blank porosity dependence on extrusion conditions is established: coefficient of drawing (λ , pressure (P, yield point (C, angle of the die (α and initial porosity (θ0. Appropriate transformations of formulas obtained by the authors, as well as numerical calculations allow to get extrusion parameters for manufacturing porous-free long-measured blanks.

  10. Mathematical model of determination of die bearing length in design of aluminum profile extrusion die

    Institute of Scientific and Technical Information of China (English)

    闫洪; 王高潮; 夏巨谌; 李志刚

    2004-01-01

    Based on the finite element simulation of profile extrusion process, the effect of local extrusion ratio, die bearing area and the distance between extrusion cylindrical center and local die orfice center on mental flow velocity was investigated. The laws of deformed metalflow on profile extrusion process were obtained. The smaller the local extrusion ratio, the faster the metal flow velocity; the smaller the area of die bearing, the faster the metal flow velocity; the smaller the distance of position of local die orifice(the closer the distance of position of local die orifice from extrusion cylindrical axis), the faster the metal flow velocity. The effect of main parameters of die structure on metal flow velocity was integrated and the mathematical model of determination of die bearing length in design of aluminum profile extrusion die was proposed. The calculated results with proposed model were well compared with the experimental results. The proposed model can be applied to determine die bearing length in design of aluminum profile extrusion die.

  11. Extrusion cooking using a twin-screw apparatus reduces toxicity of fumonisin-contaminated corn grits

    Science.gov (United States)

    Extrusion cooking using a single screw configuration reduced fumonisin concentrations of corn grits in an earlier study. Adding glucose before cooking enhanced reductions and, in one of three trials, partially reversed in vivo toxicity. To determine the effectiveness of extrusion using the more effi...

  12. Physical properties, molecular structures and protein quality of texturized whey protein isolate: effect of extrusion temperature

    Science.gov (United States)

    Extrusion is a powerful food processing operation, which utilizes high temperature and high shear force to produce a product with unique physical and chemical characteristics. Texturization of whey protein isolate (WPI) through extrusion for the production of protein fortified snack foods has provid...

  13. The Prospect of China’s Alumin-ium Extrusion Product Market

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>China’s aluminium extrusion industry can be dated back to the 1950s-70s,when the North- east 101 Plant was established in 1956,the Northwest Aluminium and Southwest Alumin- ium were completed and put into operation in 1968-1969.The three plants’ extrusion assem- bly lines were designed to produce aluminium

  14. Factors affecting irrigant extrusion during root canal irrigation: a systematic review

    NARCIS (Netherlands)

    Boutsioukis, C.; Psimma, Z.; Sluis, van der L.W.M.

    2013-01-01

    The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted

  15. A study on material flow in isothermal extrusion by FEM simulation

    Science.gov (United States)

    Peng, Zhi; Sheppard, Terry

    2004-09-01

    Numerous methods have been suggested or are being used to employ isothermal extrusion operation in commercial presses. The most popular methods may be broadly divided into two types: setting up a longitudinal thermal gradient in the billet or controlling the extrudate exit temperature by varying the ram speed. If the velocity gradient varies it could cause the extrusion to bend or twist, creating residual stress, and the same is true for variation in temperature. So, it is relevant to understand how the material flows through the die and ascertain how the flow pattern in isothermal extrusion differs from the normal extrusion process. In this study, with the help of previous experiments and finite element method (FEM) simulations, isothermal extrusion by two differing methodologies are investigated and discussed: the material flow pattern and the extrudate surface formation in isothermal extrusion. The extrusion force, the exit temperature, the temperature distribution in the transverse direction of the extrudate, the pressure on the tooling, the strain and strain rate distribution are also discussed to assist in the evaluation of isothermal extrusion.

  16. Effect of extrusion variables (temperature, moisture) on the antinutrient components of cereal brans

    National Research Council Canada - National Science Library

    Kaur, Satinder; Sharma, Savita; Singh, Baljit; Dar, B N

    2015-01-01

    .... Extrusion variables were moisture content (14, 17 and 20 %) and temperatures (115 °C, 140 °C, 165 °C). Phytic acid, polyphenols, oxalates, trypsin inhibitor, bulk density and color of brans after extrusion were analyzed...

  17. 78 FR 66895 - Aluminum Extrusions From the People's Republic of China: Preliminary Results of Changed...

    Science.gov (United States)

    2013-11-07

    ..., including, but not limited to, window frames, door frames, solar panels, curtain walls, or furniture. Such... backing material, and solar panels. The scope also excludes finished goods containing aluminum extrusions... extrusions the design and production of which are organized around meeting certain specified thermal...

  18. 76 FR 80887 - Antidumping Order on Aluminum Extrusions from the People's Republic of China: Initiation of...

    Science.gov (United States)

    2011-12-27

    ... frames, solar panels, curtain walls, or furniture. Such parts that otherwise meet the definition of..., and solar panels. The scope also excludes finished goods containing aluminum extrusions that are... sinks. Finished heat sinks are fabricated heat sinks made from aluminum extrusions the design and...

  19. Factors affecting irrigant extrusion during root canal irrigation: a systematic review

    NARCIS (Netherlands)

    Boutsioukis, C.; Psimma, Z.; van der Sluis, L.W.M.

    2013-01-01

    The aim of the present study was to conduct a systematic review and critical analysis of published data on irrigant extrusion to identify factors causing, affecting or predisposing to irrigant extrusion during root canal irrigation of human mature permanent teeth. An electronic search was conducted

  20. Process optimization diagram based on FEM simulation for extrusion of AZ31 profile

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ram speed and the billet temperature are the primary process variables that determine the quality of the extruded magnesium profile and the productivity of the extrusion operation.The optimization of the extrusion process concerns the interplay between these two variables in relation to the extrudate temperature and the peak extrusion pressure The 3D computer simulations were performed to determine the eriects of the ram speed and the billet temperature on the extrudate temperature and the peak extrusion pressure,thereby providing guidelines for the process optimization and minimizing the number of trial extrusion runs needed for the process optimization.A case study on the extrusion of an AZ31 X-shaped profile was conducted.The correlations between the process variables and the response from the deformed material,extrudate temperature and peak extrusion pressure,were established from the 3D FEM simulations and verified by the experiment.The research opens up a way to rational selection of the process variables for ensured quality and maximum productivity of the magnesium extrusion.

  1. Effect of Multiple Extrusions on the Impact Properties of Polypropylene/Clay Nanocomposites

    DEFF Research Database (Denmark)

    Klitkou, Rasmus; Jensen, Erik Appel; Christiansen, Jesper de Claville

    2012-01-01

    Polypropylene (PP)-based polymer nanocomposites containing organically modified montmorillonite (OMMT) with and without maleic anhydride grafted PP, were compounded by twin-screw extrusion. The extrusion process was repeated various numbers of times to increase the extruder residence time (TR) and...

  2. Coherence vortices of partially coherent beams in the far field

    Institute of Scientific and Technical Information of China (English)

    Liu Pu-Sheng; Lü Bai-da

    2007-01-01

    Based on the propagation law of cross-spectral density function, studied in this paper are the coherence vortices of partially coherent, quasi-monochromatic singular beams with Gaussian envelope and Schell-model correlator in the far field, where our main attention is paid to the evolution of far-field coherence vortices into intensity vortices of fully coherent beams. The results show that, although there are usually no zeros of intensity in partially coherent beams with Gaussian envelope and Schell-model correlator, zeros of spectral degree of coherence exist. The coherence vortices of spectral degree of coherence depend on the relative coherence length, mode index and positions of pairs of points.If a point and mode index are kept fixed, the position of coherence vortices changes with the increase of the relative coherence length. For the low coherent case there is a circular phase dislocation. In the coherent limit coherence vortices become intensity vortices of fully coherent Laguerre-Gaussian beams.

  3. Interferometric visibility and coherence

    Science.gov (United States)

    Biswas, Tanmoy; García Díaz, María; Winter, Andreas

    2017-07-01

    Recently, the basic concept of quantum coherence (or superposition) has gained a lot of renewed attention, after Baumgratz et al. (Phys. Rev. Lett. 113, 140401. (doi:10.1103/PhysRevLett.113.140401)), following Åberg (http://arxiv.org/abs/quant-ph/0612146), have proposed a resource theoretic approach to quantify it. This has resulted in a large number of papers and preprints exploring various coherence monotones, and debating possible forms for the resource theory. Here, we take the view that the operational foundation of coherence in a state, be it quantum or otherwise wave mechanical, lies in the observation of interference effects. Our approach here is to consider an idealized multi-path interferometer, with a suitable detector, in such a way that the visibility of the interference pattern provides a quantitative expression of the amount of coherence in a given probe state. We present a general framework of deriving coherence measures from visibility, and demonstrate it by analysing several concrete visibility parameters, recovering some known coherence measures and obtaining some new ones.

  4. Genuine quantum coherence

    Science.gov (United States)

    de Vicente, Julio I.; Streltsov, Alexander

    2017-01-01

    Any quantum resource theory is based on free states and free operations, i.e. states and operations which can be created and performed at no cost. In the resource theory of coherence free states are diagonal in some fixed basis, and free operations are those which cannot create coherence for some particular experimental realization. Recently, some problems of this approach have been discussed, and new sets of operations have been proposed to resolve these problems. We propose here the framework of genuine quantum coherence. This approach is based on a simple principle: we demand that a genuinely incoherent operation preserves all incoherent states. This framework captures coherence under additional constrains such as energy preservation and all genuinely incoherent operations are incoherent regardless of their particular experimental realization. We also introduce the full class of operations with this property, which we call fully incoherent. We analyze in detail the mathematical structure of these classes and also study possible state transformations. We show that deterministic manipulation is severely limited, even in the asymptotic settings. In particular, this framework does not have a unique golden unit, i.e. there is no single state from which all other states can be created deterministically with the free operations. This suggests that any reasonably powerful resource theory of coherence must contain free operations which can potentially create coherence in some experimental realization.

  5. Magnesium concentration effects on cruciform extrusion in supercoiled DNA examined by atomic force microscopy

    Science.gov (United States)

    Chasovskikh, S.; Dritschilo, A.

    2002-03-01

    Cruciform structures can form in DNA sequences with inverted repeats or palindromic symmetry under unwinding torsional stress. DNA repeats are widespread in the genomes of eukaryotes and prokaryotes, and their extrusion into cruciform structures may be involved in various genetic processes, including transcription and replication. Intracellular Mg 2+ may change the free energy of supercoiling to provide the driving force for cruciform extrusion. We have used atomic force microscopy (AFM) to image the effects of magnesium concentrations on cruciform extrusions in supercoiled DNA. Mg 2+ concentration dependent cruciform extrusions were observed in the supercoiled topoisomer of the pPR-PARP plasmid (=-0.065). These data show an application of AFM imaging to demonstrate that the presence of Mg 2+ results in increased extrusions and promotes compact cruciform conformation.

  6. Parametric Optimization of Simulated Extrusion of Square to Square Section Through Linear Converging Die

    Science.gov (United States)

    Mohapatra, S. K.; Maity, K. P.

    2016-02-01

    The effect of various process parameters for determining extrusion load has been studied for square to square extrusion of Al-6061 alloy, a most used aluminium alloy series in forming industries. Parameters like operating temperature, friction condition, ram velocity, extrusion ratio and die length have been chosen as an input variable for the above study. Twenty five combinations of parameters were set for the investigation by considering aforementioned five parameters in five levels. The simulations have been carried out by Deform-3D software for predicting maximum load requirement for the complete extrusion process. Effective stress and strain distribution across the billet has been checked. Operating temperature, extrusion ratio, friction factor, ram velocity and die length have the significant effect in decreasing order on the maximum load requirement.

  7. Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

    Institute of Scientific and Technical Information of China (English)

    Shihong ZHANG; Zhongtang WANG; Bing QIAO; Yi XU; Tingfeng XU

    2005-01-01

    The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080~1120℃, and the temperature range recommended for the tools is 350~500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed.With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150~200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.

  8. Crystal plasticity finite element modelling of the extrusion texture of a magnesium alloy

    Science.gov (United States)

    Shao, Yichuan; Tang, Tao; Li, Dayong; Tang, Weiqin; Peng, Yinghong

    2015-07-01

    In this paper, a crystal plasticity finite-element model (CPFEM) is developed to simulate the hot extrusion texture of the magnesium alloy AZ31. The crystal plasticity model is implemented in ABAQUS™ via user interface VUMAT subroutine. The elasto-plastic self-consistent (EPSC) model is used as the basic polycrystal framework to simulate the slip and twinning during the extrusion. Furthermore, this framework is extended to account for the effects of the dynamically recrystallized (DRX) grains on the extrusion textures. Good agreement is found between the experimentally measured and simulated textures. The simulation results show that the presence of a secondary texture component around || extrusion direction (ED) can be attributed to the lattice rotation around the c-axis during the formation of the DRX grains. In addition, the shear strain imposed on the extruded material affects the resulting texture by enhancing the basal slip mode as the material passes through the extrusion opening.

  9. FUNCTIONAL PROPERTIES OF DEFATTED CHICKPEA (CICER ARIETINUM, L. FLOUR AS INFLUENCED BY THERMOPLASTIC EXTRUSION

    Directory of Open Access Journals (Sweden)

    Maria Filomena Claret Fernandes de Aguiar VALIM

    2009-07-01

    Full Text Available

    Defatted chickpea (Cicer arietinum, L flour was submitted to thermoplastic extrusion at three feed moisture levels (13%, 18% and 27%. The functional properties of raw and extruded flours were investigated. The nitrogen solubility index of raw chickpea flour was minimum at pH 4.0 but increased at both lower and higher pHs. Extrusion reduced nitrogen solubility drastically for all feed moisture levels. Water and oil absorption capacity were significantly (p O < 05 increased after extrusion treatment. Foam stability could be improved by extrusion and was positively influenced by alkaline pH. It was also verified that extrusion cooking increased significantly (p O < 05 the emulsifying capacity of the extruded flour with 13% moisture level in water.

  10. Experimental and Numerical Study on the Strength of Aluminum Extrusion Welding

    Directory of Open Access Journals (Sweden)

    Sedat Bingöl

    2015-07-01

    Full Text Available The quality of extrusion welding in the extruded hollow shapes is influenced significantly by the pressure and effective stress under which the material is being joined inside the welding chamber. However, extrusion welding was not accounted for in the past by the developers of finite element software packages. In this study, the strength of hollow extrusion profile with seam weld produced at different ram speeds was investigated experimentally and numerically. The experiments were performed on an extruded hollow aluminum profile which was suitable to obtain the tensile tests specimens from its seam weld’s region at both parallel to extrusion direction and perpendicular to extrusion direction. A new numerical modeling approach, which was recently proposed in literature, was used for numerical analyses of the study. The simulation results performed at different ram speeds were compared with the experimental results, and a good agreement was obtained.

  11. Hot Melt Extrusion for Sustained Protein Release: Matrix Erosion and In Vitro Release of PLGA-Based Implants.

    Science.gov (United States)

    Cossé, Anne; König, Corinna; Lamprecht, Alf; Wagner, Karl G

    2017-01-01

    The design of biodegradable implants for sustained release of proteins is a complex challenge optimizing protein polymer interaction in combination with a mini-scale process which is predictive for production. The process of hot melt extrusion (HME) was therefore conducted on 5- and 9-mm mini-scale twin screw extruders. Poly(lactic-co-glycolic acid) (PLGA) implants were characterized for their erosion properties and the in vitro release of the embedded protein (bovine serum albumin, BSA). The release of acidic monomers as well as other parameters (pH value, mass loss) during 16 weeks indicated a delayed onset of matrix erosion in week 3. BSA-loaded implants released 17.0% glycolic and 5.9% lactic acid after a 2-week lag time. Following a low burst release (3.7% BSA), sustained protein release started in week 4. Storage under stress conditions (30°C, 75% rH) revealed a shift of erosion onset of 1 week (BSA-loaded implants: 26.9% glycolic and 9.3% lactic acid). Coherent with the changed erosion profiles, an influence on the protein release was observed. Confocal laser scanning and Raman microscopy showed a homogenous protein distribution throughout the matrix after extrusion and during release studies. Raman spectra indicated a conformational change of the protein structure which could be one reason for incomplete protein release. The study underlined the suitability of the HME process to obtain a solid dispersion of protein inside a polymeric matrix providing sustained protein release. However, the incomplete protein release and the impact by storage conditions require thorough characterization and understanding of erosion and release mechanisms.

  12. Extrusão de misturas de castanha do Brasil com mandioca Extrusion of Brazil nut and cassava flour mixtures

    Directory of Open Access Journals (Sweden)

    Maria Luzenira de Souza

    2008-06-01

    Full Text Available Considerando-se que a castanha do Brasil apresenta elevado potencial nutritivo, baixo consumo no Brasil, baixo valor agregado e é um produto orgânico, além da alta produtividade, do baixo custo da mandioca e da tecnologia de extrusão termoplástica apresentarem ampla aplicabilidade e vantagens, este trabalho teve como objetivo empregar estas três variáveis, para formular misturas com castanha do Brasil e farinha de mandioca e processá-las por extrusão, visando à obtenção de produtos extrusados ricos em proteína vegetal e prontos para o consumo. Foram utilizadas torta de amêndoa de castanha do Brasil semidesengordurada e farinha de mandioca para formulações das misturas para extrusão. Aplicou-se o delineamento fatorial completo composto central (2³, com 3 variáveis independentes e a metodologia de superfície de resposta foi usada para avaliar os resultados da composição centesimal e o valor calórico, frente às variações de castanha, umidade e temperatura. Os resultados indicam que as formulações com maiores quantidades de castanha apresentam quantidades de proteínas, lipídios e cinzas mais elevadas, já as formulações com menores teores de castanha apresentam maiores percentuais de carboidratos. Os coeficientes de regressão médios do modelo estatístico para as respostas são: umidade 7,40; carboidratos 51,09; proteínas 15,34; lipídios 11,77; fibra total 9,92 e kcal 371,65. Os ensaios com menores teores de castanha e maiores de farinha apresentam-se mais expandidos e de cor clara, enquanto que aqueles com maiores teores de castanha não se expandem e têm a cor acinzentada. Conclui-se que a adição de castanha semidesengordurada à farinha de mandioca pode ser submetida à extrusão, originando um produto extrusado fonte de proteína vegetal, pronto para o consumo e que pode atender à exigência de consumidores que não utilizam proteínas de origem animal.Considering that Brazil nut presents high nutritional

  13. The Effects of Process Parameters on Evolutions of Thermodynamics and Microstructures for Composite Extrusion of Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    H.-J. Hu

    2013-01-01

    Full Text Available To research the effects of process parameters on evolutions of extrusion force and temperature rise and microstructures for composite extrusion of magnesium alloy which includes initial extrusion and shearing process subsequently and is shortened for “ES” in this paper, the ES extrusion process has been researched by using finite element modeling (FEM technology. The rules of temperature rise and the extrusion force varying with process parameters have been developed. The thermal-mechanical coupling finite element models including the geometric and FEM models and solution conditions were applied to calculate the effective strain and temperature and extrusion force during ES extrusion. The maximum temperature rises in the billets do not increase with billet temperature rising. The temperature of rod surface increased continuously with development of ES extrusion. The evolutions of extrusion load curve and effective stress and temperature can be divided into three stages obviously. Extrusion experiments have been constructed to validate the FEM models with different process conditions. The simulation results and microstructure observation showed that ES process can introduce compressive and accumulated shear strain into the magnesium alloy. The ES extrusion would cause severe plastic deformation and improve the dynamic recrystallization during ES extrusion. The microstructures show that ES is an efficient and inexpensive grain refinement method for magnesium alloys.

  14. Stimulated coherent transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hung-chi Lihn

    1996-03-01

    Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of electrons in the bunch. In typical accelerators, this factor is about 8 to 11 orders of magnitude. The spectrum of the coherent radiation is determined by the Fourier transform of the electron bunch distribution and, therefore, contains information of the bunch distribution. Coherent transition radiation emitted from subpicosecond electron bunches at the Stanford SUNSHINE facility is observed in the far-infrared regime through a room-temperature pyroelectric bolometer and characterized through the electron bunch-length study. To measure the bunch length, a new frequency-resolved subpicosecond bunch-length measuring system is developed. This system uses a far-infrared Michelson interferometer to measure the spectrum of coherent transition radiation through optical autocorrelation with resolution far better than existing time-resolved methods. Hence, the radiation spectrum and the bunch length are deduced from the autocorrelation measurement. To study the stimulation of coherent transition radiation, a special cavity named BRAICER is invented. Far-infrared light pulses of coherent transition radiation emitted from electron bunches are delayed and circulated in the cavity to coincide with subsequent incoming electron bunches. This coincidence of light pulses with electron bunches enables the light to do work on electrons, and thus stimulates more radiated energy. The possibilities of extending the bunch-length measuring system to measure the three-dimensional bunch distribution and making the BRAICER cavity a broadband, high-intensity, coherent, far-infrared light source are also discussed.

  15. Genetic Architecture of Anther Extrusion in Spring and Winter Wheat

    Directory of Open Access Journals (Sweden)

    Quddoos H. Muqaddasi

    2017-05-01

    Full Text Available Hybrid wheat breeding is gaining prominence worldwide because it ensures higher and more static yield than conventionally bred varieties. The cleistogamous floral architecture of wheat (Triticum aestivum L. impedes anthers inside the floret, making it largely an inbreeder. For hybrid seed production, high anther extrusion is needed to promote cross pollination and to ensure a high level of pollen availability for the seed plant. This study, therefore, aimed at the genetic dissection of anther extrusion (AE in panels of spring (SP, and winter wheat (WP accessions by genome wide association studies (GWAS. We performed GWAS to identify the SNP markers potentially linked with AE in each panel separately. Phenotypic data were collected for 3 years for each panel. The average levels of Pearson's correlation (r among all years and their best linear unbiased estimates (BLUEs within both panels were high (r(SP = 0.75, P < 0.0001;r(WP = 0.72, P < 0.0001. Genotypic data (with minimum of 0.05 minor allele frequency applied included 12,066 and 12,191 SNP markers for SP and WP, respectively. Both genotypes and environment influenced the magnitude of AE. In total, 23 significant (|log10(P| > 3.0 marker trait associations (MTAs were detected (SP = 11; WP = 12. Anther extrusion behaved as a complex trait with significant markers having either favorable or unfavorable additive effects and imparting minor to moderate levels of phenotypic variance (R2(SP = 9.75−14.24%; R2 (WP = 9.44−16.98%. All mapped significant markers as well as the markers within their significant linkage disequilibrium (r2 ≥ 0.30 regions were blasted against wheat genome assembly (IWGSC1+popseq to find the corresponding genes and their high confidence descriptions were retrieved. These genes and their orthologs in Hordeum vulgare, Brachypodium distachyon, Oryza sativa, and Sorghum bicolor revealed syntenic genomic regions potentially involved in flowering-related traits. Moreover, the

  16. Tube extrusion of AZ31 alloy with Sr additions

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Alireza, E-mail: Alireza.Sadeghi@mail.mcgill.ca [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada); Hoseini, Majid; Pekguleryuz, Mihriban [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Bending and unbending of material flow during extrusion tilts the basal pole from the center of the pole figure. Black-Right-Pointing-Pointer Circumferential movement of material inside the welding zone forms two extra texture components. Black-Right-Pointing-Pointer Addition of Sr removes Al from {alpha}-Mg as a result grains could deform more easily in the circumferential directions. Black-Right-Pointing-Pointer By increasing level of Sr, maximum intensity of the ODFs decreases while the extra texture components strengthen. - Abstract: Three Mg alloys (AZ31, and AZ31 + 0.4 and 0.8 wt%Sr) were successfully hot extruded into tubes at 400 Degree-Sign C through a porthole die. Strontium (Sr) additions to AZ31 alloy reduced twining and the dynamically recrystallized grain size. However, Sr also increased the surface cracking tendency during extrusion. It was noted that the complex deformation path in the porthole die distributes the Sr-rich precipitates homogeneously across the microstructure and stringer formation is effectively avoided. The material flow in the die resembles that seen in multiple equal channel angular pressing (ECAP) routes and similar and significant effects on the final texture are observed. The material flow curvatures in the extrusion direction rotate the basal poles 25 Degree-Sign from the radial direction. Two other texture components ({delta}{sub 1}, {delta}{sub 2}) are also formed in the welding zone by the circumferential flow of material. The maximum intensity of the orientation distribution function (ODF) is reduced with increasing level of Sr. Noteworthy, the maximum intensity in AZ31 + 0.8Sr occurs at the {delta}{sub 1} component while for AZ31 and AZ31 + 0.4Sr, the maximum intensity is located at the basal components. With Sr, alloying, Al is depleted from Mg solid solution and grains deform more easily in the circumferential direction. As a result, selective workhardening

  17. SAR image effects on coherence and coherence estimation.

    Energy Technology Data Exchange (ETDEWEB)

    Bickel, Douglas Lloyd

    2014-01-01

    Radar coherence is an important concept for imaging radar systems such as synthetic aperture radar (SAR). This document quantifies some of the effects in SAR which modify the coherence. Although these effects can disrupt the coherence within a single SAR image, this report will focus on the coherence between separate images, such as for coherent change detection (CCD) processing. There have been other presentations on aspects of this material in the past. The intent of this report is to bring various issues that affect the coherence together in a single report to support radar engineers in making decisions about these matters.

  18. Carbonate- and silicate-rich globules in the kimberlitic rocks of northwestern Tarim large igneous province, NW China: Evidence for carbonated mantle source

    Science.gov (United States)

    Cheng, Zhiguo; Zhang, Zhaochong; Santosh, M.; Hou, Tong; Zhang, Dongyang

    2014-12-01

    We report carbonate- and silicate-rich globules and andradite from the Wajilitage kimberlitic rocks in the northwestern Tarim large igneous province, NW China. The carbonate-rich globules vary in size from 1 to 3 mm, and most have ellipsoidal or round shape, and are composed of nearly pure calcite. The silicate-rich globules are elliptical to round in shape and are typically larger than the carbonate-rich globules ranging from 2 to several centimeters in diameter. They are characterized by clear reaction rims and contain several silicate minerals such as garnet, diopside and phlogopite. The silicate-rich globules, reported here for the first time, are suggested to be related to the origin of andradite within the kimberlitic rocks. Our results show that calcite in the carbonate-rich globules has a high XCa (>0.97) and is characterized by extremely high concentrations of the total rare earth elements (up to 1500 ppm), enrichment in Sr (8521-10,645 ppm) and LREE, and remarkable depletion in Nd, Ta, Zr, Hf and Ti. The calcite in the silicate-rich globules is geochemically similar to those in the carbonate-rich globules except the lower trace element contents. Garnet is dominantly andradite (And59.56-92.32Grs5.67-36.03Pyr0.36-4.61Spe0-0.33) and is enriched in light rare earth elements (LREEs) and relatively depleted in Rb, Ba, Th, Pb, Sr, Zr and Hf. Phlogopite in the silicate-rich globules has a high Mg# ranging from 0.93 to 0.97. The composition of the diopside is Wo45.82-51.39En39.81-49.09Fs0.88-0.95 with a high Mg# ranging from 0.88 to 0.95. Diopside in the silicate-rich globules has low total rare earth element (REE) contents (14-31 ppm) and shows middle REE- (Eu to Gd), slight light REE- and heavy REE-enrichment with elevated Zr, Hf and Sr contents and a negative Nb anomaly in the normalized diagram. The matrix of the kimberlitic rocks are silica undersaturated (27.92-29.31 wt.% SiO2) with low Al2O3 (4.51-5.15 wt.%) and high CaO (17.29-17.77 wt.%) contents. The

  19. Pellet manufacturing by extrusion-spheronization using process analytical technology

    DEFF Research Database (Denmark)

    Sandler, Niklas; Rantanen, Jukka; Heinämäki, Jyrki

    2005-01-01

    The aim of this study was to investigate the phase transitions occurring in nitrofurantoin and theophylline formulations during pelletization by extrusion-spheronization. An at-line process analytical technology (PAT) approach was used to increase the understanding of the solid-state behavior...... hydrate (nitrofurantoin), dehydration was observed at higher temperatures. To reach an understanding of the process and to find the critical process parameters, the use of complementary analytical techniques are absolutely necessary when signals from APIs and different excipients overlap each other....... of the active pharmaceutical ingredients (APIs) during pelletization. Raman spectroscopy, near-infrared (NIR) spectroscopy, and X-ray powder diffraction (XRPD) were used in the characterization of polymorphic changes during the process. Samples were collected at the end of each processing stage (blending...

  20. A Review of Dynamic Models of Hot-Melt Extrusion

    Directory of Open Access Journals (Sweden)

    Jonathan Grimard

    2016-06-01

    Full Text Available Hot-melt extrusion is commonly applied for forming products, ranging from metals to plastics, rubber and clay composites. It is also increasingly used for the production of pharmaceuticals, such as granules, pellets and tablets. In this context, mathematical modeling plays an important role to determine the best process operating conditions, but also to possibly develop software sensors or controllers. The early models were essentially black-box and relied on the measurement of the residence time distribution. Current models involve mass, energy and momentum balances and consists of (partial differential equations. This paper presents a literature review of a range of existing models. A common case study is considered to illustrate the predictive capability of the main candidate models, programmed in a simulation environment (e.g., MATLAB. Finally, a comprehensive distributed parameter model capturing the main phenomena is proposed.

  1. MULTIPARTICULATE DRUG DELIVERY SYSTEM: PELLETIZATION THROUGH EXTRUSION AND SPHERONIZATION

    Directory of Open Access Journals (Sweden)

    Anshuli Sharma

    2013-02-01

    Full Text Available Pharmaceutical invention and research are increasingly focusing on delivery systems which enhance desirable therapeutic objectives while minimising side effects. Recent trends indicate that multiparticulate drug delivery systems are especially suitable for achieving controlled or delayed release oral formulations with low risk of dose dumping, flexibility of blending to attain different release patterns as well as reproducible and short gastric residence time. Pelletization is a technique used to prepare fine powders into pellets used as multiparticulate drug delivery systems. There are different pelletization techniques used to prepare pellets. Extrusion and spheronization is one of them used to prepare pellets drug loaded beads/pellets for extended release or sustained release oral formulations such as tablets and capsules.

  2. Scalable Approach for Extrusion and Perfusion of Tubular, Heterotypic Biomaterials

    Science.gov (United States)

    Jeronimo, Mark David

    Soft material tubes are critical in the vasculature of mammalian tissues, forming networks of blood vessels and airways. Homogeneous and heterogeneous hydrogel tubes were extruded in a one-step process using a three layer microfluidic device. Co-axial cylindrical flow of crosslinking solutions and an alginate matrix is generated by a radial arrangement of microfluidic channels at the device's vertical extrusion outlet. The flow is confined and begins a sol-gel transition immediately as it extrudes at velocities upwards of 4 mm/s. This approach allows for predictive control over the dimensions of the rapidly formed tubular structures for outer diameters from 600 microm to 3 mm. A second microfluidic device hosts tube segments for controlled perfusion and pressurization using a reversible vacuum seal. On-chip tube deflection is observed and modeled as a measure of material compliance and circumferential elasticity. I anticipate applications of these devices for perfusion cell culture of cell-laden hydrogel tubes.

  3. Characterization of extrusion flow using particle image velocimetry

    Directory of Open Access Journals (Sweden)

    2009-09-01

    Full Text Available The aim of this study was the characterization of polymer flows within an extrusion die using particle image velocimetry (PIV in very constraining conditions (high temperature, pressure and velocity. Measurements were realized on semi-industrial equipments in order to have test conditions close to the industrial ones. Simple flows as well as disrupted ones were studied in order to determine the capabilities and the limits of the method. The analysis of the velocity profiles pointed out significant wall slip, which was confirmed by rheological measurements based on Mooney's method. Numerical simulations were used to connect the two sets of measurements and to simulate complex velocity profiles for comparison to the experimental ones. A good agreement was found between simulations and experiments providing wall slip is taken into account in the simulation.

  4. Some physicochemical properties of dextrin produced by extrusion process

    Directory of Open Access Journals (Sweden)

    Achmat Sarifudin

    2014-06-01

    Full Text Available Dextrinization of corn starch by twin screw extruder was studied. The effect of extruder operating conditions (five different screw speeds: 35, 45, 55, 65, and 70; and three temperatures: 125, 130, and 135 °C on some physicochemical properties of dextrin (total soluble solid, water absorption index, water solubility index, and total color difference was investigated. Results showed that as the screw speed and temperature of extrusion were increased the water absorption index of dextrin tended to drop meanwhile the total soluble solid, water solubility index, and color were inclined to rise. The range of total soluble solid, water absorption index, water solubility index and total color difference was 2.1–4.6 Brix, 159–203%, 20–51%, 3.5–14.1, respectively.

  5. Gel-extrusion: A new continuous forming technique

    Energy Technology Data Exchange (ETDEWEB)

    Millan, A.J. [Department of Materials, IUT Federico Rivero Palacios, Caracas (Venezuela); Santacruz, I.; Sanchez-Herencia, A.J.; Nieto, M.I.; Moreno, R. [Instituto de Ceramica y Vidrio, CSIC, Camino de Valdelatas s/n, E-28048, Cantoblanco, Madrid (Spain)

    2002-12-01

    In recent years a variety of direct shaping methods has been developed for the near-net shaping of ceramic powders. The main aim in developing these methods is to provide a simple route for manufacturing bulk complex-shaped bodies with increased green resistance in order to reduce or avoid final machining, which is the most expensive step in the fabrication process. This communication reports a novel processing route for the continuous manufacture of ceramic and/or metal hollow or solid bodies based on the extrusion of aqueous suspensions that contain a small amount (<1 wt.-%) of a gelling additive that gelates on passing through a refrigerated die. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  6. Visualization of the Crystallization in Foam Extrusion Process

    Science.gov (United States)

    Tabatabaei Naeini, Alireza

    In this study, crystal formation of polypropylene (PP) and poly lactic acid (PLA) in the presence of CO2 in foam extrusion process was investigated using a visualization chamber and a CCD camera. The role of pre-existing crystals on the foaming behavior of PP and PLA were studied by characterizing the foam morphology. Visualization results showed that crystals formed within the die before foaming and these crystals affect the cell nucleation behavior and expansion ratio of PP and PLA significantly. Due to the fast crystallization kinetics of PP, crystallinity should be optimum to achieve uniform cell structure with high cell density and high expansion ratio. In PLA, enhancement of crystallinity is crucial for getting foam with a high expansion ratio. It was also visualized that CO2 significantly suppresses the crystallization temperature in PP through the plasticization effect as well as its influence on flow induced crystallinity.

  7. Thermal modelling of extrusion based additive manufacturing of composite materials

    DEFF Research Database (Denmark)

    Jensen, Mathias Laustsen; Sonne, Mads Rostgaard; Hattel, Jesper Henri

    2017-01-01

    One of the hottest topics regarding manufacturing these years is additive manufacturing (AM). AM is a young branch of manufacturing techniques, which by nature is disruptive due to its completely different manufacturing approach, wherein material is added instead of removed. By adding material...... process knowledge, and validating the generated toolpaths before the real manufacturing process takes place: Hence removing time consuming and expensive trial-and-error processes for new products. This study applies a 2D restricted finite volume model aimed to describe thermoplastic Acrylonitrille......-butadiene-styrene (ABS) and thermosetting polyurethane (PU) material extrusion processes. During the experimental evaluation of the produced models it is found that some critical material properties needs to be further investigated to increase the precision of the model. It is however also found that even with only...

  8. The Sytykanskaya kimberlite pipe:Evidence from deep-seated xenoliths and xenocrysts for the evolution of the mantle beneath Alakit, Yakutia, Russia

    Institute of Scientific and Technical Information of China (English)

    I.V. Ashchepkov; I.V. Makovchuk; V.S. Palesskiy; 0.S. Khmel’nikova; A.M. Logvinova; L.F. Reimers; T. Ntaflos; Z.V. Spetsius; N.V. Vladykin; H. Downes; D.S. Yudin; A.V. Travin

    2015-01-01

    Mantle xenoliths (>150) and concentrates from late autolithic breccia and porphyritic kimberlite from the Sytykanskaya pipe of the Alakit field (Yakutia) were analyzed by EPMA and LAM ICP methods. In P-T-X-f(O2) diagrams minerals from xenoliths show widest variations, the trends P-Fe#-CaO, f(O2) for minerals from porphyric kimberlites are more stepped than for xenocrysts from breccia. Ilmenite PTX points mark moving for protokimberlites from the lithosphere base (7.5 GPa) to pyroxenite lens (5e3.5 GPa) accompanied by Cr increase by AFC and creation of two trends P-Fe#Ol w10e12% and 13e15%. The Opx-Gar-based mantle geotherm in Alakit field is close to 35 mW/m2 at 65 GPa and 600 ?C near Moho was determined. The oxidation state for the megacrystalline ilmenites is lower for the metasomatic associations due to reduction of protokimberlites on peridotites than for uncontaminated varieties at the lithosphere base. Highly inclined linear REE patterns with deep HFSE troughs for the parental melts of clinopyroxene and garnet xenocrysts from breccia were influenced by differentiated protokimberlite. Melts for metasomatic xenoliths reveal less inclined slopes without deep troughs in spider diagrams. Garnets reveal S-shaped REE patterns. The clinopyroxenes from graphite bearing Cr-websterites show inclined and inflected in Gd spectrums with LREE variations due to AFC differen-tiation. Melts for garnets display less inclined patterns and Ba-Sr troughs but enrichment in Nb-Ta-U. The 40Ar/39Ar ages for micas from the Alakit mantle xenoliths for disseminated phlogopites reveal Proterozoic (1154 Ma) age of metasomatism in early Rodinia mantle. Veined glimmerites with richterite e like amphiboles mark w1015 Ma plume event in Rodinia mantle. The w600e550 Ma stage manifests final Rodinia break-up. The last 385 Ma metasomatism is protokimberlite-related.

  9. Dynamic coherent backscattering mirror

    Energy Technology Data Exchange (ETDEWEB)

    Zeylikovich, I.; Xu, M., E-mail: mxu@fairfield.edu [Physics Department, Fairfield University, Fairfield, CT 06824 (United States)

    2016-02-15

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation.

  10. Coherence for Monoidal Endofunctors

    CERN Document Server

    Dosen, K

    2009-01-01

    The goal of this paper is to prove coherence results with respect to relational graphs for monoidal endofunctors, i.e. endofunctors of a monoidal category that preserve the monoidal structure up to a natural transformation that need not be an isomorphism. These results are proved first in the absence of symmetry in the monoidal structure, and then with this symmetry. In the later parts of the paper the coherence results are extended to monoidal endofunctors in monoidal categories that have diagonal or codiagonal natural transformations, or where the monoidal structure is given by finite products or coproducts. Monoidal endofunctors are interesting because they stand behind monoidal monads and comonads, for which coherence will be proved in a sequel to this paper.

  11. Dynamic coherent backscattering mirror

    Science.gov (United States)

    Xu, M.

    2016-01-01

    The phase of multiply scattered light has recently attracted considerable interest. Coherent backscattering is a striking phenomenon of multiple scattered light in which the coherence of light survives multiple scattering in a random medium and is observable in the direction space as an enhancement of the intensity of backscattered light within a cone around the retroreflection direction. Reciprocity also leads to enhancement of backscattering light in the spatial space. The random medium behaves as a reciprocity mirror which robustly converts a diverging incident beam into a converging backscattering one focusing at a conjugate spot in space. Here we first analyze theoretically this coherent backscattering mirror (CBM) phenomenon and then demonstrate the capability of CBM compensating and correcting both static and dynamic phase distortions occurring along the optical path. CBM may offer novel approaches for high speed dynamic phase corrections in optical systems and find applications in sensing and navigation. PMID:26937296

  12. Coherence in Microchip Traps

    CERN Document Server

    Treutlein, P; Steinmetz, T; Hänsch, T W; Reichel, J; Treutlein, Philipp; Hommelhoff, Peter; Steinmetz, Tilo; H\\"ansch, Theodor W.; Reichel, Jakob

    2003-01-01

    We report the coherent manipulation of internal states of neutral atoms in a magnetic microchip trap. Coherence lifetimes exceeding 1 s are observed with atoms at distances of $4-130 \\mu$m from the microchip surface. The coherence lifetime in the microtrap is independent of atom-surface distance and agrees well with the results of similar measurements in macroscopic magnetic traps. Due to the absence of surface-induced decoherence, a miniaturized atomic clock with a relative stability in the $10^{-13}$ range can be realized. For applications in quantum information processing, we propose to use microwave near-fields in the proximity of chip wires to create potentials that depend on the internal state of the atoms.

  13. Physical Simulation Method for the Investigation of Weld Seam Formation During the Extrusion of Aluminum Alloys

    Science.gov (United States)

    Fang, Gang; Nguyen, Duc-Thien; Zhou, Jie

    2016-12-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of great importance to understand the formation of weld seams inside the welding chamber during extrusion, as affected by extrusion process variables and die design. Previously developed physical simulation methods could not fully reproduce the thermomechanical conditions inside the welding chamber of porthole die. In this research, a novel physical simulation method for the investigation of weld seam formation during extrusion was developed. With a tailor-designed tooling set mounted on a universal testing machine, the effects of temperature, speed, and strain on the weld seam quality of the 6063 alloy were investigated. The strains inside the welding chamber were found to be of paramount importance for the bonding of metal streams, accompanied by microstructural changes, i.e., recovery or recrystallization, depending on the local deformation condition. The method was shown to be able to provide guidelines for the design of porthole dies and choice of extrusion process variables, thereby reducing the scrap rate of aluminum extrusion operation.

  14. Fractional ultrabasic-basic evolution of upper-mantle magmatism: Evidence from xenoliths in kimberlites, inclusions in diamonds and experiments

    Science.gov (United States)

    Litvin, Yuriy; Kuzyura, Anastasia

    2017-04-01

    Ultrabasic peridotites and pyroxenites together with basic eclogites are the upper-mantle in situ rocks among xenoliths in kimberlites. Occasionally their diamond-bearing varieties have revealed within the xenoliths. Therewith the compositions of rock-forming minerals demonstrate features characteristic for primary diamond-included minerals of peridotite and eclogite parageneses (the elevated contents of Cr-component in peridotitic garnets and Na-jadeitic component in eclogitic clinopyroxenes). High-pressure experimental study of melting equilibria on the multicomponent peridotie-pyroxenite system olivine Ol - orthopyroxene Opx - clinopyroxene Cpx - garnet Grt showed that Opx disappeared in the peritectic reaction Opx+L→Cpx (Litvin, 1991). As a result, the invariant peritectic equilibrium Ol+Opx+Cpx+Grt+L of the ultrabasic system was found to transform into the univariant cotectic assemblage Ol+Cpx+Grt+L. Further experimental investigation showed that olivine reacts with jadeitic component (Jd) with formation of garnet at higher 4.5 GPa (Gasparik, Litvin, 1997). Study of melting relations in the multicomponent system Ol - Cpx - Jd permits to discover the peritectic point Ol+Omph+Grt+L (where Omph - omphacitic clinopyroxene) at concentration 3-4 wt.% Jd-component in the system. The reactionary loss of Opx and Ol makes it possible to transform the 4-phase garnet lherzolite ultrabasic association into the bimineral eclogite assemblage. The regime of fractional Ol, Cpx and Grt crystallization must be accompanied by increasing content of jadeitic component in residual melts that causes the complete "garnetization of olivine". In the subsequent evolution, the melts would have to fractionate for basic SiO2-saturated compositions responsible for petrogenesis of eclogite varieties marked with accessory corundum Crn, kyanite Ky and coesite Coe. Both the peritectic mechanisms occur in regime of fractional crystallization. The sequence of the upper-mantle fractional

  15. Maintaining Web Cache Coherency

    Directory of Open Access Journals (Sweden)

    2000-01-01

    Full Text Available Document coherency is a challenging problem for Web caching. Once the documents are cached throughout the Internet, it is often difficult to keep them coherent with the origin document without generating a new traffic that could increase the traffic on the international backbone and overload the popular servers. Several solutions have been proposed to solve this problem, among them two categories have been widely discussed: the strong document coherency and the weak document coherency. The cost and the efficiency of the two categories are still a controversial issue, while in some studies the strong coherency is far too expensive to be used in the Web context, in other studies it could be maintained at a low cost. The accuracy of these analysis is depending very much on how the document updating process is approximated. In this study, we compare some of the coherence methods proposed for Web caching. Among other points, we study the side effects of these methods on the Internet traffic. The ultimate goal is to study the cache behavior under several conditions, which will cover some of the factors that play an important role in the Web cache performance evaluation and quantify their impact on the simulation accuracy. The results presented in this study show indeed some differences in the outcome of the simulation of a Web cache depending on the workload being used, and the probability distribution used to approximate updates on the cached documents. Each experiment shows two case studies that outline the impact of the considered parameter on the performance of the cache.

  16. Coherent light microscopy

    CERN Document Server

    Ferraro, Pietro; Zalevsky, Zeev

    2011-01-01

    This book deals with the latest achievements in the field of optical coherent microscopy. While many other books exist on microscopy and imaging, this book provides a unique resource dedicated solely to this subject. Similarly, many books describe applications of holography, interferometry and speckle to metrology but do not focus on their use for microscopy. The coherent light microscopy reference provided here does not focus on the experimental mechanics of such techniques but instead is meant to provide a users manual to illustrate the strengths and capabilities of developing techniques. Th

  17. Coherent states measurement entropy

    CERN Document Server

    Kwapien, J; Zyczkowski, K; Kwapien, Jaroslaw; Slomczynski, Wojciech; Zyczkowski, Karol

    1996-01-01

    Coherent states (CS) quantum entropy can be split into two components. The dynamical entropy is linked with the dynamical properties of a quantum system. The measurement entropy, which tends to zero in the semiclassical limit, describes the unpredictability induced by the process of a quantum approximate measurement. We study the CS--measurement entropy for spin coherent states defined on the sphere discussing different methods dealing with the time limit n \\to \\infty. In particular we propose an effective technique of computing the entropy by iterated function systems. The dependence of CS--measurement entropy on the character of the partition of the phase space is analysed.

  18. Coherent terahertz photonics.

    Science.gov (United States)

    Seeds, Alwyn J; Fice, Martyn J; Balakier, Katarzyna; Natrella, Michele; Mitrofanov, Oleg; Lamponi, Marco; Chtioui, Mourad; van Dijk, Frederic; Pepper, Michael; Aeppli, Gabriel; Davies, A Giles; Dean, Paul; Linfield, Edmund; Renaud, Cyril C

    2013-09-23

    We present a review of recent developments in THz coherent systems based on photonic local oscillators. We show that such techniques can enable the creation of highly coherent, thus highly sensitive, systems for frequencies ranging from 100 GHz to 5 THz, within an energy efficient integrated platform. We suggest that such systems could enable the THz spectrum to realize its full applications potential. To demonstrate how photonics-enabled THz systems can be realized, we review the performance of key components, show recent demonstrations of integrated platforms, and give examples of applications.

  19. Co-extrusion as manufacturing technique for multilayer mini-matrices with dual drug release.

    Science.gov (United States)

    Dierickx, L; Remon, J P; Vervaet, C

    2013-11-01

    The aim of this work was to develop by means of co-extrusion a multilayered dosage form characterized by a dual release profile of the same drug. Co-extrudates consisted of two concentric polymer matrices: a core having a lipophilic character and a coat with a hydrophilic character. Diclofenac sodium (DS) was incorporated as model drug in both layers. Several polymers were screened on the basis of their processability via hot melt extrusion (HME) and in vitro drug release. Polymer combinations with suitable properties (i.e., similar extrusion temperature, appropriate drug release profile) were processed via co-extrusion. (Co-) extruded samples were characterized in terms of solid state (XRD, SEM), in vitro drug release, core/coat adhesion, and bioavailability. Based on the polymer screening, two polymer combinations were selected for co-extrusion: ethylcellulose (core) combined with Soluplus® (coat) and polycaprolactone (core) with PEO (coat). These combinations were successfully co-extruded. XRD revealed that DS remained crystalline during extrusion in ethylcellulose, Soluplus®, polycaprolactone, and PEO. The polycaprolactone/PEO combination could be processed at a lower temperature (70 °C), vs. 140 °C for ethylcellulose/Soluplus®. The maximum drug load in core and coat depended on the extrusion temperature and the die dimensions, while adhesion between core and coat was mainly determined by the drug load and by the extrusion temperature. In vitro drug release from the co-extruded formulations was reflected in the in vivo behavior: formulations with a higher DS content in the coat (i.e., faster drug release) resulted in higher Cmax and higher AUC values. Co-extrusion is a viable method to produce in a single step a multilayer dosage form with dual drug release.

  20. Coherency matrix formulation for partially coherent imaging to evaluate the degree of coherence for image.

    Science.gov (United States)

    Yamazoe, Kenji

    2012-08-01

    This paper defines a matrix from which coherence property of imaging by partially coherent Koehler illumination is determined. The matrix termed coherency matrix in imaging system is derived by the space average of a product of a column vector and its transpose conjugate where each row of the column vector represents mutually incoherent light. The coherency matrix in imaging system has similar properties to the polarization matrix that is utilized for calculating the light intensity and degree of polarization of polarized light. The coherency matrix in imaging system enables us to calculate not only image intensity but also degree of coherence for image. Simulation results of the degree of coherence for image given by the coherency matrix in imaging system correspond to the complex degree of coherence obtained by the van Cittert-Zernike theorem.

  1. Coherence Constraints and the Last Hidden Optical Coherence

    CERN Document Server

    Qian, Xiao-Feng; Vamivakas, A Nick; Eberly, Joseph H

    2016-01-01

    We have discovered a new domain of optical coherence, and show that it is the third and last member of a previously unreported fundamental triad of coherences. These are unified by our derivation of a parallel triad of coherence constraints that take the form of complementarity relations. We have been able to enter this new coherence domain experimentally and we describe the novel tomographic approach devised for that purpose.

  2. EXTRUSION FORMING OF A DOUBLE BASE SOLID ROCKET PROPELLANT BY FINITE ELEMENT METHOD

    Directory of Open Access Journals (Sweden)

    Barış KALAYCIOĞLU

    2007-01-01

    Full Text Available In this study, three dimensional modelling of extrusion forming of a double base solid rocket propellant is performed on Ansys® finite element simulation package. For the purpose of initial model construction and later comparisons with elastoviscoplastik model, the solid propellant is assumed to obey the elastic-plastic material response during the direct extrusion process. Taking into account the contact surface behavior with Coulomb friction and geometric and material nonlinearities, an incremental large large strain solution methodology has been adapted in the simulation. The hydrostatic pressure, stress, strain, and displacement values during extrusion of the solid rocket propellant are obtained from the simulation.

  3. Modelling extrudate expansion in a twin-screw food extrusion cooking process through dimensional analysis methodology

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    2010-01-01

    A new phenomenological model is proposed to correlate extrudate expansion and extruder operation parameters in a twin-screw food extrusion cooking process. Buckingham's pi dimensional analysis method is applied to establish the model. Three dimensionless groups, i.e. pump efficiency, water content...... and temperature, are formed to model the extrusion process from dimensional analysis. The model is evaluated with experimental data for extrusion of whole wheat flour and fish feed. The average deviations of the model correlations are 5.9% and 9% based on experimental data for the whole wheat flour and fish feed...

  4. THE EFFECT OF BLOWING AGENTS ON THE EFFECTIVENESS OF POLY(VINYL CHLORIDE EXTRUSION

    Directory of Open Access Journals (Sweden)

    Tomasz Garbacz

    2016-12-01

    Full Text Available The cellular extrusion is a method for manufacturing profiles, bars, low density cellu-lar coatings and other cellular products that have no hollow cavities on the surface and show minimal processing shrinkage, while their properties are similar to those of products produced by conventional extrusion. The paper deals with cellular extrusion of PVC. The investigation of the process was conducted using state-of-the-art endothermic and exothermic blowing agents that were dosed in up to 1.5% by weight. The experiments involved measuring output, energy consumption and energy efficiency of the process.

  5. The Coherence of Autism

    Science.gov (United States)

    Hobson, R. Peter

    2014-01-01

    There is a growing body of opinion that we should view autism as fractionable into different, largely independent sets of clinical features. The alternative view is that autism is a coherent syndrome in which principal features of the disorder stand in intimate developmental relationship with each other. Studies of congenitally blind children…

  6. Dental Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Kun-Feng Lin

    2013-07-01

    Full Text Available This review paper describes the applications of dental optical coherence tomography (OCT in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

  7. Bicartesian Coherence Revisited

    CERN Document Server

    Dosen, K

    2007-01-01

    A survey is given of results about coherence for categories with finite products and coproducts. For these results, which were published previously by the authors in several places, some formulations and proofs are here corrected, and matters are updated. The categories investigated in this paper formalize equality of proofs in classical and intuitionistic conjunctive-disjunctive logic without distribution of conjunction over disjunction.

  8. Coherence without Additivity.

    OpenAIRE

    2002-01-01

    The Dutch book argument is a coherence condition for the existence of subjective probabilities. This note gives a general framework of analysis for this argument in a nonadditive probability setting. Particular cases are given by comonotonic and affinely related Dutch books that lead to Choquet expectations and Min expectations.

  9. Coherently combining antennas

    Science.gov (United States)

    Dybdal, Robert B. (Inventor); Curry, Samuel J. (Inventor)

    2009-01-01

    An apparatus includes antenna elements configured to receive a signal including pseudo-random code, and electronics configured to use the pseudo-random code to determine time delays of signals incident upon the antenna elements and to compensate the signals to coherently combine the antenna elements.

  10. Multiphoton coherent population oscillation

    CERN Document Server

    Sharypov, A V

    2014-01-01

    We study the bichromatic driving of a two-level system which displays long-lived coherent population oscillations (CPO). We show that under certain conditions, multiphoton parametric interaction leads to the appearance of CPO resonances at the subharmonic frequencies. In addition, in the region of the CPO resonances, there is strong parametric interaction between the weak sideband components of the electromagnetic field.

  11. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Andersen, Peter E.

    2015-01-01

    Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. Mapping the local reflectivity, OCT visualizes the morphology of the sample, in real time or at video rate. In addition...

  12. Coherent states in quantum mechanics

    CERN Document Server

    Rodrigues, R D L; Fernandes, D

    2001-01-01

    We present a review work on the coherent states is non-relativistic quantum mechanics analysing the quantum oscillators in the coherent states. The coherent states obtained via a displacement operator that act on the wave function of ground state of the oscillator and the connection with Quantum Optics which were implemented by Glauber have also been considered. A possible generalization to the construction of new coherent states it is point out.

  13. Coherent hybrid electromagnetic field imaging

    Science.gov (United States)

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  14. Atraumatic surgical extrusion using periotome in esthetic zone: A case series

    Directory of Open Access Journals (Sweden)

    P Mohan Kumar

    2013-01-01

    The technique presented is an alternative approach to periodontal surgical procedures consisting orthodontic extrusion and osseous recontouring. It does not result in functional or esthetic deformities especially in the anterior esthetic zone.

  15. RESEARCH ON THE SELECTION OF FRICTION MODELS IN THE FINITE ELEMENT SIMULATION OF WARM EXTRUSION

    Institute of Scientific and Technical Information of China (English)

    X.B. Lin; H.S. Xiao; Z.L. Zhang

    2003-01-01

    During the process of finite element simulation of precision warm forging, the selec-tion of friction models has a direct effect on the precision accuracy of finite elementsimulation results. Among all the factors which influence the selection of frictionmodels, the distribution rule of normal stress at the tool-workpiece interface is a keyone. To find out the distribution rule of normal stress at the tool-workpiece inter-face, this paper has made a systematic research on three typical plastic deformationprocesses: forward extrusion, backward extrusion, and lateral extrusion by a methodof finite element simulation. Then on the base of synthesizing and correcting tradi-tional friction models, a new general friction model which is fit for warm extrusion isdeveloped at last.

  16. Optimal forming zone length in continuous extrusion of lead-clad glass fiber wire

    Institute of Scientific and Technical Information of China (English)

    李霞; 唐景林; 王丽薇; 高明

    2008-01-01

    Forming zone length (FZL) is a key parameter of the lead-clad glass fiber extrusion dies, and an unsuitable FZL will lead to breakage of the glass fiber and/or unacceptable geometric and metallographic qualities of the product. The optimal FZL was determined theoretically based on a mathematical model established by upper bound method, and accepted Pb-GF wire was actually obtained experimentally by symmetric side-feed extrusion at a much lower temperature than that published before. The wire has features of fine grains, uniform diameter, good coaxiality and satisfied mechanical property. The results and conclusions obtained in the research can be used to design the forming tools for lead-clad glass fiber extrusion and have significance to further research on the extrusion of other complex wires of metal-clad brittle core.

  17. AFSC/RACE/SAP/Swiney: Primiparous and multiparous Tanner crab egg extrusion, embryo development and hatching

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study compares timing of egg extrusion, embryo development, timing and duration of eclosion, and incubation periods of Kodiak, Alaska primiparous and...

  18. Modeling and numerical simulation of multiflux die in the multilayer co-extrusion process

    Science.gov (United States)

    Mun, Jun Ho; Kim, Ju Hyeon; Mun, Sang Ho; Kim, See Jo

    2017-02-01

    It is of great importance to understand the stretching and folding mechanism in the multiflux co-extrusion die to get uniform multilayer distribution at the end of die lip in the multilayer co-extrusion processes. In this work, to understand the mechanism of the layer distribution, modeling and numerical simulation were carried out for three-dimensional flow analysis in the multilayer co-extrusion die. The multilayer flow fields were numerically visualized and analyzed on the arbitrary cross-section of the multiflux die. In addition, numerical results for the multiflux die characteristics were obtained for non-Newtonian fluids in terms of power-law index for the cross model, which will be useful for the optimal design of screw and die, simultaneously, in the multilayer co-extrusion process.

  19. Structure optimization of porthole die based on aluminum profile extrusion process numerical simulation

    Institute of Scientific and Technical Information of China (English)

    WU Xiang-hong; ZHAO Guo-qun; LUAN Yi-guo; LOU Shu-mei; MA Xin-wu

    2006-01-01

    Porthole die extrusion method is used to produce hollow aluminum profile. Due to the complexity of the porthole die structure and the material flow, it is very difficult to get ideal profile products with the firstly designed die structure. Finite volume numerical simulation was used to analyze the extrusion process of a hollow profile with porthole die and the problem of non-uniform material flow was found. Optimization was made to the originally designed die to solve the problem. Lower load, reasonable seaming location and even extruded forepart with uniform material flow in the optimized die extrusion were obtained. Guidelines to porthole die design were given and it is also concluded that finite volume method with Eulerian description avoids mesh regeneration and is suitable to numerical simulation of severe deformation processes, such as profile extrusion.

  20. Effect of Process Variables on the Formation of Streak Defects on Anodized Aluminum Extrusions: An Overview

    Science.gov (United States)

    Zhu, Hanliang; Couper, Malcolm J.; Dahle, Arne K.

    2012-04-01

    Streak defects are often present on anodized extrusions of 6xxx series aluminum alloys, increasing the fabrication cost of these products. Moreover, streaking often only becomes visible after etching and anodizing treatments, rather than in the as-extruded condition, making it difficult to identify the original causes and influencing factors of these defects. In this paper, various process variables that influence the formation of streak defects on anodized aluminium extrusions are reviewed on the basis of a literature review, industrial practice and experimental results. The influencing factors involved in various processing steps such as billet quality, extrusion process, die design and etching process are considered. Effective measures for preventing the formation of streak defects in industrial extrusion products are discussed.

  1. [New extrusion products in diet therapy of diseases of internal organs].

    Science.gov (United States)

    Meshcheriakova, V A; Plotnikova, O A; Iatsyshina, T A; Sharafetdinov, Kh Kh; Faĭvishevskiĭ, M L; Lisina, T N

    1995-01-01

    Therapeutic effectiveness of 3 new extrusion foods was studied in control conditions of clinic of Institute of nutrition RAMS. The foods were produced by Institute of meat industry RAS on basis of meat resources and wheat brans. The samples of extrusion foods were differed by contents of protein (17-23 g%) and dietary fibers (up to 10%) and used in therapeutic diet for patients with insulin-dependent diabetes mellitus. It was shown that of all three extrusion foods caused decreasing of dyspeptic symptoms during first week of intake and normalisation of intestinal functions without using of laxatives unlike of control group of patients eating standard diabetic diet. It was shown also a decreasing of cholesterol in blood serum of patients received of extrusion foods No 1 and No 3. These samples are recommended for diet therapy and preventive nutrition of patients with metabolic disorders and hypomotoricity of intestinal tract as resources of dietary fibers and protein.

  2. The Effect of Paraffinic Mineral Oil Lubrication in Cold Forward Extrusion

    Directory of Open Access Journals (Sweden)

    Mohd Hafis - Sulaiman

    2011-09-01

    Full Text Available This paper presents the results of cold forward extrusion modelling and the analysis of the contact sliding behaviour on the die-billet surface by paraffinic mineral oil lubrication with kinematic viscosity of 92 mm2/s at 40 °C. The analysis dealt with the plasticity flow that was investigated by finite element method in order to identify the loads acting on the billet. The finite element analysis of stresses was performed based on load distributions calculated from experimental test. The time behaviour of the displacements on the billet was then used as inputs for the extrusion model. The present method provided good results with reduced computation time. The results of the extrusion model revealed that the zones of high stress situated at the sharp edges of the die, which explains the observed extrusion force to reach a peak value.

  3. PVC Extrusion Development and Production for the NOvA Neutrino Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Talaga, R. L. [Argonne; Grudzinski, J. J. [Argonne; Phan-Budd, S. [Argonne; Pla-Dalmau, A. [Fermilab; Fagan, J. E. [Fermilab; Grozis, C. [Fermilab; Kephart, K. M. [Fermilab

    2016-01-05

    We have produced large and highly-reflective open-cell PVC extrusions for the NOvA neutrino oscillation experiment. The extrusions were sealed, instrumented, assembled into self-supporting detector blocks, and filled with liquid scintillator. Each Far Detector block stands 15.7 m high, is 15.7 m wide and 2.1 m thick. More than 22,000 extrusions were produced with high dimensional tolerance and robust mechanical strength. This paper provides an overview of the NOvA Far Detector, describes the preparation of the custom PVC powder, and the making of the extrusions. Quality control was a key element in the production and is described in detail.

  4. PVC Extrusion Development and Production for the NOvA Neutrino Experiment

    CERN Document Server

    Talaga, R L; Phan-Budd, S; Pla-Dalmau, A; Fagan, J E; Grozis, C; Kephart, K M

    2016-01-01

    We have produced large and highly-reflective open-cell PVC extrusions for the NOvA neutrino oscillation experiment. The extrusions were sealed, instrumented, assembled into self-supporting detector blocks, and filled with liquid scintillator. Each Far Detector block stands 15.7 m high, is 15.7 m wide and 2.1 m thick. More than 22,000 extrusions were produced with high dimensional tolerance and robust mechanical strength. This paper provides an overview of the NOvA Far Detector, describes the preparation of the custom PVC powder, and the making of the extrusions. Quality control was a key element in the production and is described in detail.

  5. PVC extrusion development and production for the NOvA neutrino experiment

    Science.gov (United States)

    Talaga, R. L.; Grudzinski, J. J.; Phan-Budd, S.; Pla-Dalmau, A.; Fagan, J. E.; Grozis, C.; Kephart, K. M.

    2017-07-01

    We have produced large and highly-reflective open-cell PVC extrusions for the NOvA neutrino oscillation experiment. The extrusions were sealed, instrumented, assembled into self-supporting detector blocks, and filled with liquid scintillator. Each Far Detector block stands 15.7 m high, is 15.7 m wide and 2.1 m thick. More than 22,000 extrusions were produced with high dimensional tolerance and robust mechanical strength. This paper provides an overview of the NOvA Far Detector, describes the preparation of the custom PVC powder, and the making of the extrusions. Quality control was a key element in the production and is described in detail.

  6. THE EFFECT OF BLOWING AGENTS ON THE EFFECTIVENESS OF POLY(VINYL CHLORIDE) EXTRUSION

    National Research Council Canada - National Science Library

    Garbacz, Tomasz; Jachowicz, Tomasz; Tor-Świątek, Aneta

    2016-01-01

    .... The paper deals with cellular extrusion of PVC. The investigation of the process was conducted using state-of-the-art endothermic and exothermic blowing agents that were dosed in up to 1.5% by weight...

  7. Effect of extrusion temperature on the physical properties of high-silicon aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    YANG Fuliang; GAN Weiping; CHEN Zhaoke

    2007-01-01

    Light-weight high-silicon aluminum alloys are used for electronic packaging in the aviation and space- flight industry. Al-30Si and Al-40Si are fabricated with air- atomization and vacuum-canning hot-extrusion process. The density, thermal conductivity, hermeticity and thermal expan- sion coefficients of the material are measured, and the relationship between extrusion temperature and properties is obtained. Experimental results show that the density of high- silicon aluminum alloys prepared with this method is as high as 99.64% of the theory density, and increases with elevating extrusion temperature. At the same time, thermal conductiv- ity varies between 104-140W/(m.K); with the extrusion temperature, thermal expansion coefficient also increases but within 13 × 10-6 (at 100℃) and hermeticity of the material is high to 10-9 order of magnitude.

  8. Rectal extrusion of the catheter and air ventriculography following bowel perforation in ventriculo-peritoneal shunt

    Energy Technology Data Exchange (ETDEWEB)

    Arico, M.; Podesta, A.F.; Bianchi, E.; Beluffi, G.; Fiori, P.; Chiari, G.; Pezzotta, S.

    1985-01-01

    Ventriculo-peritoneal shunt is frequently carried out in infantile hydrocephalus. The peritoneal shunt has a lower morbidity than ventriculo-atrial shunt and severe complications are uncommon. Abdominal complications include intestinal perforation, shunt migration, inguinal hernia, cerebrospinal fluid pseudocysts and hollow viscus perforation. A few cases of catheter extrusion from the rectum, vagina, umbilicus and urethra have been described. We report a new case of intestinal perforation with rectal extrusion of the catheter associated with a ventriculogram.

  9. Optical Coherence and Quantum Optics

    CERN Document Server

    Mandel, Leonard

    1995-01-01

    This book presents a systematic account of optical coherence theory within the framework of classical optics, as applied to such topics as radiation from sources of different states of coherence, foundations of radiometry, effects of source coherence on the spectra of radiated fields, coherence theory of laser modes, and scattering of partially coherent light by random media. The book starts with a full mathematical introduction to the subject area and each chapter concludes with a set of exercises. The authors are renowned scientists and have made substantial contributions to many of the topi

  10. Prediction of Extrusion Pressure And Product Deflection Of Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    D.T. GUNDU

    2013-01-01

    Full Text Available - In this paper artificial neural network was used as a modeling tool for simulation and prediction of extrusion pressure and product deflection of extrudes of lead alloys. An extensive experimental program was undertaken to extrude a lead (Pb alloy on ELE Compact-1500 compression machine. The neural model of extrusion pressure and product deflection was developed based on groups of experiments carried out as samples, Eight (8 die bearing parameters (die bearing length, radius of curvature, slip angle, die angle, die ratio ram displacement, pocket depth and die diameter were used as inputs into the network architecture of 8 [4-3]2 2 in predicting the extrusion pressure and product deflection. After series of network architectures were trained using different training algorithms such as Levenberg-Marquardt, Bayesian Regulation, Resilient Backpropagation using MATLAB 7.9.0 (R20096, the LM8 [4-3]2 2 was selected as the most appropriate model. Prediction of the neural model exhibited reasonable correlation with the experimental extrusion pressure and product deflection. The predicted extrusion pressure and product deflection gave reasonable errors and higher correlation coefficients indicating that the model is robust for predicting extrusion pressure and product deflection.

  11. Quantum coherence: Reciprocity and distribution

    Science.gov (United States)

    Kumar, Asutosh

    2017-03-01

    Quantum coherence is the outcome of the superposition principle. Recently, it has been theorized as a quantum resource, and is the premise of quantum correlations in multipartite systems. It is therefore interesting to study the coherence content and its distribution in a multipartite quantum system. In this work, we show analytically as well as numerically the reciprocity between coherence and mixedness of a quantum state. We find that this trade-off is a general feature in the sense that it is true for large spectra of measures of coherence and of mixedness. We also study the distribution of coherence in multipartite systems by looking at monogamy-type relation-which we refer to as additivity relation-between coherences of different parts of the system. We show that for the Dicke states, while the normalized measures of coherence violate the additivity relation, the unnormalized ones satisfy the same.

  12. Spectral coherence in windturbine wakes

    Energy Technology Data Exchange (ETDEWEB)

    Hojstrup, J. [Riso National Lab., Roskilde (Denmark)

    1996-12-31

    This paper describes an experiment at a Danish wind farm to investigate the lateral and vertical coherences in the nonequilibrium turbulence of a wind turbine wake. Two meteorological masts were instrumented for measuring profiles of mean speed, turbulence, and temperature. Results are provided graphically for turbulence intensities, velocity spectra, lateral coherence, and vertical coherence. The turbulence was somewhat influenced by the wake, or possibly from aggregated wakes further upstream, even at 14.5 diameters. Lateral coherence (separation 5m) seemed to be unaffected by the wake at 7.5 diameters, but the flow was less coherent in the near wake. The wake appeared to have little influence on vertical coherence (separation 13m). Simple, conventional models for coherence appeared to be adequate descriptions for wake turbulence except for the near wake situation. 3 refs., 7 figs., 1 tab.

  13. Coherent branching feature bisimulation

    Directory of Open Access Journals (Sweden)

    Tessa Belder

    2015-04-01

    Full Text Available Progress in the behavioral analysis of software product lines at the family level benefits from further development of the underlying semantical theory. Here, we propose a behavioral equivalence for feature transition systems (FTS generalizing branching bisimulation for labeled transition systems (LTS. We prove that branching feature bisimulation for an FTS of a family of products coincides with branching bisimulation for the LTS projection of each the individual products. For a restricted notion of coherent branching feature bisimulation we furthermore present a minimization algorithm and show its correctness. Although the minimization problem for coherent branching feature bisimulation is shown to be intractable, application of the algorithm in the setting of a small case study results in a significant speed-up of model checking of behavioral properties.

  14. Current advances and future perspectives in extrusion-based bioprinting.

    Science.gov (United States)

    Ozbolat, Ibrahim T; Hospodiuk, Monika

    2016-01-01

    Extrusion-based bioprinting (EBB) is a rapidly growing technology that has made substantial progress during the last decade. It has great versatility in printing various biologics, including cells, tissues, tissue constructs, organ modules and microfluidic devices, in applications from basic research and pharmaceutics to clinics. Despite the great benefits and flexibility in printing a wide range of bioinks, including tissue spheroids, tissue strands, cell pellets, decellularized matrix components, micro-carriers and cell-laden hydrogels, the technology currently faces several limitations and challenges. These include impediments to organ fabrication, the limited resolution of printed features, the need for advanced bioprinting solutions to transition the technology bench to bedside, the necessity of new bioink development for rapid, safe and sustainable delivery of cells in a biomimetically organized microenvironment, and regulatory concerns to transform the technology into a product. This paper, presenting a first-time comprehensive review of EBB, discusses the current advancements in EBB technology and highlights future directions to transform the technology to generate viable end products for tissue engineering and regenerative medicine.

  15. Sleeveless-extrusion cannula for levitation of dislocated intraocular lens.

    Science.gov (United States)

    Agarwal, Ashvin; Narang, Priya; Agarwal, Amar; Kumar, Dhivya A

    2014-07-01

    To characterise a sleeveless-extrusion cannula-based suction technique to levitate dislocated intraocular lens (IOLs) and review the surgical outcome. This retrospective, non-comparative, single surgeon, interventional, consecutive case series examined 10 patients (10 eyes) who underwent the surgical procedure from October 2011 to December 2012. Reliability, reproducibility, and intraoperative and postoperative complications of the technique were analysed. The technique involved suction levitation of a 3-piece acrylic foldable IOL in six cases, 1-piece acrylic foldable IOL in three cases and a plate haptic IOL in one case. The IOL was exchanged in four eyes whereas the same IOL was repositioned in six eyes with sulcus repositioning in two eyes and glued intrascleral fixation in four eyes. Intraoperative suction loss and a subsequent IOL dislocation were reported in 1 (10%) eye. Early preoperative complications included pigment dispersion in 1 (10%) eye, grade 2 anterior chamber cellular reaction in 2 (20%) eyes and intraoperative corneal oedema in 1 (10%) eye which resolved with medical line of management. Intermediate and late complications included macular oedema in one patient (10%) which resolved considerably with medical line of management. No incidence of postoperative vitreous or retinal haemorrhage, retinal break or retinal detachment was reported. The early results demonstrate this surgical intervention as a reliable, reproducible and an effective alternative treatment option for levitation of dislocated IOLs with a low complication rate.

  16. Inhomogeneity in microstructure and mechanical properties during twist extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Noor, Sh. Vakili [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Eivani, A.R., E-mail: aeivani@iust.ac.ir [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Jafarian, H.R. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mirzaei, M. [Material Engineering Group, Islamic Azad University, Kermanshah (Iran, Islamic Republic of)

    2016-01-15

    In the present paper, the effect of twist extrusion (TE) on the variations of hardness and tensile properties in commercial pure copper is investigated. It is found that hardness, yield and ultimate tensile strength of the alloy increased by increasing distance from the center of the sample after one pass TE. Similar consequences are observed when the second pass of deformation is considered. This is attributed to inhomogeneity of deformation and the higher strain imposed on the material at the peripheral regions. It should be noted that the inhomogeneity is increased at the second pass when route A of deformation is utilized and reduces by utilization of route D. This has as a well-established effect on the development of microstructure throughout the cross section of the samples. In fact, it is found that the microstructure at the peripheral regions is more significantly deformed leading to higher dislocation density and extensive subgrain formation. In addition, it is found that at the second pass using route A, inhomogeneity of deformation and microstructure increases. However, less inhomogeneity is observed when route D is utilized which is in line with the hardness and tensile test results. In the end, it is concluded that depending on the aim of the SPD process, if more homogeneous deformation and microstructure is required, route D is recommended and route A should be utilized in case if maximum inhomogeneity is desirable.

  17. Manufacture of long lengths of HTSC wires by extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, T.; Bhargava, A.; Golden, S.; Zhao, R.; Page, D.; Barry, J.; Mackinnon, I.D.R. [Univ. of Queensland, St. Lucia (Australia). Centre for Microscopy and Microanalysis

    1994-12-31

    Powders of YBa{sub 2}Cu{sub 3}O{sub 7} were prepared by co-precipitation using aqueous solution of nitrates and oxalic acid. Precipitated powders were then filtered and dried. The dried powders were calcined at 500C or 800C and mixed with 2wt% of hydroxypropylmethylcellulose and small amounts of water. Long lengths of superconducting YBa{sub 2}Cu{sub 3}O{sub 7} wires were fabricated by means of extrusion followed by sintering. The maximum critical current density, J{sub c}, 1,100 A/cm{sup 2} (in transport) was obtained for samples prepared from 500C calcined powder and sintered at 920C. To improve J{sub c}, Y211 phase was also introduced to the calcined powder mix and extruded with binder. The maximum J{sub c} obtained by these techniques was 200 A/cm{sup 2}. A long length of wire was also extruded from the mixture of calcined Y123 powder, HPMC and a small amount of water. J{sub c} measurements show sintered density and absence of macro-pores are critical to maintain J{sub c} values. In long lengths of wire for which this condition holds the reduction of J{sub c} value with wire distance is minimal.

  18. Utilization and Fortification of Patin Fish on Extrusion Snack

    Directory of Open Access Journals (Sweden)

    Mala Nurilmala

    2014-11-01

    Full Text Available Catfish (Pangasius sp. is a well cultured freshwater fish. Fortification improves protein level in snack and an effort to vary catfish fish product. The purpose of this study was to determine drying method for fish grit, formulation of snack and its properties. Grit formation by several drying methods and proximate (AOAC and degree of polarization. Snack used based on the physical measurement, namely development ratio. Formulations of grit composition of corn: rice: fish were 70%:30%:0% (K, 65%:25%:10% (A, 62.5%:22.5%:15% (B, 60%:20%:20% (C. Fish addition only effect the color of snack based on sensory analysis. There was no effect on snacks physical properties both 10% and 15% of fish grit added. Chemical measurements comprised water, ash, lipid, protein levels and polarization degree. Statistical analysis showed that fish addition effect the protein level on extrusion snack. In addition, polarization measurement showed that the snack with fish addition of 10% (A and 15%( B are fully gelatinized.Keyword: formulation, patin fish, snack

  19. Bioavailability enhancement of atovaquone using hot melt extrusion technology.

    Science.gov (United States)

    Kate, Laxman; Gokarna, Vinod; Borhade, Vivek; Prabhu, Priyanka; Deshpande, Vinita; Pathak, Sulabha; Sharma, Shobhona; Patravale, Vandana

    2016-04-30

    Emerging parasite resistance and poor oral bioavailability of anti-malarials are the two cardinal issues which hinder the clinical success of malaria chemotherapy. Atovaquone-Proguanil is a WHO approved fixed dose combination used to tackle the problem of emerging resistance. However, Atovaquone is a highly lipophilic drug having poor aqueous solubility (less than 0.2 μg/ml) thus reducing its oral bioavailability. The aim of the present investigation was to explore hot melt extrusion (HME) as a solvent-free technique to enhance solubility and oral bioavailability of Atovaquone and to develop an oral dosage form for Atovaquone-Proguanil combination. Solid dispersion of Atovaquone was successfully developed using HME. The solid dispersion was characterized for DSC, FTIR, XRD, SEM, and flow properties. It was filled in size 2 hard gelatin capsules. The formulation showed better release as compared to Malarone® tablets, and 3.2-fold and 4.6-fold higher bioavailability as compared to Malarone® tablets and Atovaquone respectively. The enhanced bioavailability also resulted in 100% anti-malarial activity in murine infection model at 1/8(th) therapeutic dose. Thus the developed methodology shows promising potential to solve the problems associated with Atovaquone therapy, namely its high cost and poor oral bioavailability, resulting in increased therapeutic efficacy of Atovaquone.

  20. Leavened dough processing by supercritical fluid extrusion (SCFX).

    Science.gov (United States)

    Hicsasmaz, Zeynep; Dogan, Esref; Chu, Cindy; Rizvi, Syed S H

    2003-10-08

    Yeast-leavened dough processing is semicontinuous due to the requirement for fermentation at constant temperature and humidity. Also, new regulations on the emission of alcohols are becoming burdensome on the baking industry. Extrusion processing of dough with supercritical carbon dioxide (SC-CO(2)) is envisioned to alleviate emission problems and to decrease production time by eliminating fermentation. A bread dough formulation with 50% (w/w) moisture was leavened by injecting 1.5% (w/w) SC-CO(2) in a twin-screw extruder at 37 degrees C. Specific mechanical energy input was 260 kJ/kg. The operating apparent shear rate range was 60-260 s(-1). SCFX-leavened dough density (420-430 kg/m(3)) was in good agreement with values reported for similar doughs. The flow behavior index, obtained by an on-line slit rheometer, was 0.49 for the nonleavened control and 0.63 for the SCFX-leavened dough. Apparent viscosity of the SCFX-leavened dough varied from 37 to 23 Pa-s. This new continuous process offers attractive possibilities for industrial applications if further developed.

  1. Extrusion Roller Imprinting with a Variotherm Belt Mold

    Directory of Open Access Journals (Sweden)

    Raymond Frenkel

    2014-12-01

    Full Text Available Although many precision fabrication techniques have demonstrated the ability to produce microstructures and micro-devices with sub 100 nm accuracy, we are yet to see a scalable manufacturing process for large-area production. One promising solution to scalable micro- and nanofabrication is thermal roller imprinting. However, existing investigations on thermal roller imprinting revealed poor pattern transfer fidelity, especially for high aspect ratio features. The standard roller imprinting process suffers from the lack of an effective holding and cooling stage so that the adverse effects from the viscoelastic nature of polymers are not managed. To rectify this problem and further improve the production rate, a new extrusion roller imprinting process with a variotherm belt mold is designed, and its prototype was established at a laboratory scale. The process testing results demonstrate that a 30 μm sawtooth pattern can be faithfully transferred to extruded polyethylene film at take-up speeds higher than 10 m/min. The results are promising in that microfeatures or even nanofeatures may be successfully replicated by a robust and scalable industrial process suitable for large-area, continuous production.

  2. Coherent Transient Systems Evaluation

    Science.gov (United States)

    1993-06-17

    manuscript is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints...for governmental purposes. 1.0 Introduction The continuous optical correlator presented here is based on the phenomena of coherent transients, also...Gating the Continuous Processor Programming the continuous processor is accomplished by illuminati , n, the material with ,.’ modulated light pulses: a

  3. Pellets de trigo e soja produzidos por extrusão Wheat and soybean pellets produced by extrusion-cooking

    Directory of Open Access Journals (Sweden)

    Sin Huei Wang

    2008-09-01

    Full Text Available A mistura de trigo e soja representa uma importante fonte calórico-protéica com proteínas de boa qualidade. Apesar disso, a utilização da soja como ingrediente tem sido limitada pelo seu sabor de feijão cru (beany flavor, o qual é melhorado pelo processo de extrusão. Foram estudados os efeitos de umidade da mistura, Temperatura de Barril (TB e Velocidade de Rotação de Parafuso (VRP, Nº 5 do extrusor no Índice de Expansão (IE, no Índice de Solubilidade em Água (ISA e nas características sensoriais de pellets produzidos com mistura de trigo e soja (90:10, objetivando a otimização deste processo para a obtenção de pellets fritos com melhores qualidades sensoriais. A farinha mista crua foi extrusada em 2 umidades (32 e 35%, 4 TB (60 a 90 °C e 4 VRP (60 a 150 rpm, totalizando 32 tratamentos. O pellet frito, preparado com a farinha mista com 32% de umidade e extrusada em 60 rpm a 80 °C, apresentou o maior IE e as melhores qualidades sensoriais (aparência, sabor e textura, sendo preferido pela equipe de provadores não treinados, tanto com sabor de bacon como com sabor de queijo.The mixture of wheat with soybean represents an important calorie-protein source with good protein quality. In spite of this, the use of soybeans as an ingredient has been limited by their beany flavor, which is improved by the extrusion process. Effects of mixture moisture, Barrel Temperature (BT and Screw-Speed (SS, Nº 5 on Expansion Index (EI, Water Solubility Index (WSI and sensory characteristics of pellets produced with a wheat-soybean (90:10 mixture were studied, in order to optimize this process for obtaining fried pellets with better sensory qualities. Raw mixed flour was extruded at two moisture contents (32 and 35%, four BT (60 to 90 °C and four SS (60 to 150 rpm, totalizing 32 treatments. The fried pellets, prepared with the mixed flour with 32% moisture and extruded at 60 rpm and 80 °C, presented the greatest EI and the best sensory

  4. Alterações bromatológicas em soja e milho processados por extrusão Chemical changes in soybean and corn processed by extrusion

    Directory of Open Access Journals (Sweden)

    Liandra Maria Abaker Bertipaglia

    2008-11-01

    Full Text Available Avaliaram-se os efeitos da temperatura do processo de extrusão sobre as características das frações nitrogenadas e dos carboidratos, do extrato etéreo, da digestibilidade in vitro da proteína e do fator antitríptico da soja e do milho. O experimento foi conduzido em delineamento experimental inteiramente casualizado, com três repetições, em esquema fatorial 5 × 4, composto de cinco combinações de soja e milho (100% soja; 75% soja e 25% milho; 50% soja e 50% milho; 25% soja e 75% milho; 100% milho, com base na matéria seca e quatro temperaturas de extrusão (sem extrusão; e extrusão a 80, 100 ou 120ºC. O processo de extrusão promoveu aumento na fração lipídica e redução nos teores de fibra em detergente neutro (FDN e fibra em detergente ácido (FDA, que variaram de acordo com a proporção de milho e soja e com a temperatura de processamento, conseqüentemente, os teores de proteína insolúvel em detergente neutro (PIDN e proteína insolúvel em detergente ácido (PIDA sofreram redução. A mesma tendência foi observada nos teores de lignina, que foram menores nas misturas com até 50% de soja, processadas a 120ºC. A extrusão, independentemente da temperatura, promoveu aumento da fração A dos carboidratos, tanto no milho como na soja. Nas frações B2 e C diminuíram com a maior participação de soja na mistura. A extrusão reduziu as frações nitrogenadas A, B1 e C, fato observado nas misturas contendo soja. O processamento promoveu aumento da fração B2, exceto no milho a 100%. Alterações menos significativas foram observadas na fração B3. O processamento por extrusão não altera a digestibilidade in vitro da proteína de milho e soja, no entanto, reduz a quantidade de inibidor de tripsina quando as misturas desses grãos são processadas a 120ºC.The effects of temperatures of extrusion process on characteristics of nitrogen and carbohydrates fractions, ether extract, in vitro protein digestibility and

  5. Coherent laser vision system

    Energy Technology Data Exchange (ETDEWEB)

    Sebastion, R.L. [Coleman Research Corp., Springfield, VA (United States)

    1995-10-01

    The Coherent Laser Vision System (CLVS) is being developed to provide precision real-time 3D world views to support site characterization and robotic operations and during facilities Decontamination and Decommissioning. Autonomous or semiautonomous robotic operations requires an accurate, up-to-date 3D world view. Existing technologies for real-time 3D imaging, such as AM laser radar, have limited accuracy at significant ranges and have variability in range estimates caused by lighting or surface shading. Recent advances in fiber optic component technology and digital processing components have enabled the development of a new 3D vision system based upon a fiber optic FMCW coherent laser radar. The approach includes a compact scanner with no-moving parts capable of randomly addressing all pixels. The system maintains the immunity to lighting and surface shading conditions which is characteristic to coherent laser radar. The random pixel addressability allows concentration of scanning and processing on the active areas of a scene, as is done by the human eye-brain system.

  6. Photoacoustics with coherent light

    Directory of Open Access Journals (Sweden)

    Emmanuel Bossy

    2016-03-01

    Full Text Available Since its introduction in the mid-nineties, photoacoustic imaging of biological tissue has been one of the fastest growing biomedical imaging modality, and its basic principles are now considered as well established. In particular, light propagation in photoacoustic imaging is generally considered from the perspective of transport theory. However, recent breakthroughs in optics have shown that coherent light propagating through optically scattering medium could be manipulated towards novel imaging approaches. In this article, we first provide an introduction to the relevant concepts in the field, and then review the recent works showing that it is possible to exploit the coherence of light in conjunction with photoacoustics. We illustrate how the photoacoustic effect can be used as a powerful feedback mechanism for optical wavefront shaping in complex media, and conversely show how the coherence of light can be exploited to enhance photoacoustic imaging, for instance in terms of spatial resolution or for designing minimally invasive endoscopic devices. Finally, we discuss the current challenges and perspectives down the road towards practical applications in the field of photoacoustic imaging.

  7. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  8. Effect of Equal Channel Angular Extrusion on the Microstructures and Properties of Two Extruded Al-Mg-Si Alloys

    Institute of Scientific and Technical Information of China (English)

    M. Cai; G. W. Lorimer

    2005-01-01

    The effect of equal channel angular extrusion (ECAE) on the microstructure of two Al-Mg-Si extrusion alloys was investigated by high resolution electron backscattered diffraction (EBSD) using a field emission gun scanning electron microscope (FEG-SEM) and a transmission electron microscope (TEM). Two contrasting alloys: a dilute alloy, based on alloy 6061 and a concentrated alloy, based on alloy 6069 were employed for this research. It has been found that prior ECAE to extrusion promotes high angle grain boundaries (HAGBs) in the extrusions, and the increase in HAGBs ratio is due to the large shear deformation involved in the processof ECAE. Tensile testing results show that a further ageing treatment strengthens the alloys after extrusion and the ECAE processedextrusions are more ductile than conventional extrusions.

  9. Zircon geochronology and geochemistry of mafic xenoliths from Liaoning kimberlites:Track the early evolution of the lower crust, North China Craton

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jianping; YU Chunmei; LU Fengxiang; LI Huimin

    2004-01-01

    Mafic xenoliths from Paleozoic Fuxian kimberlites (Liaoning Province) mainly include garnet granulite, with minor pyroxene amphibolite, meta-gabbro and pyroxene syenite. The SiO2 contents of the xenoliths are from 47.3 wt% to 49.9 wt%. The granulites are mainly coarse-medium grained and reasonably with well-developed granoblastic (mostly polygonal)texture, contain the assemblage of garnet + plagioclase + pyroxene + K-feldspar ± phlogopite.The mineral assemblage of the amphibolites is plagioclase + pyroxene + amphibole ± K-feldspar,with the equilibrium temperature and pressure conditions of 744-821 ℃ and 0.76-0.88 GPa.The granulites are regarded as derivation from the lower crust depth (more than 29 km), below the amphibolites. Garnet granulites compositionally correspond to sub-alkalic basalt, and have wide ranges of Ni abundance (133-840 ppm), and Nb/Y (0.12-1.85), Nb/U (3.51-53.86) and Ta/U (0.38-2.48). The amphibolite and the syenite correspond to alkalic basalt. The Fuxian mafic xenoliths are regarded as the metamorphic product of the underplated magmas (including fractional crystallization or not) experienced the contamination with the pre-existed crustal components, and partly effected by kimberlitic magmas. The concordant ages of zircons for the gabbro (2610-2580 Ma) and the near-concordant upper intercept ages of zircons for the garnet granulite and pyroxene amphibolite (2578-2538 Ma) indicate that they are currently known as the oldest deep-seated xenoliths from the lower crust of the North China Craton. These ages recorded the formation of the united Eastern Block of the North China Craton, That is, Neoarchean (2.6-2.5 Ga) is an important continental crustal growth period of the North China Craton.The lower intercept age of the garnet granulite (1853 Ma) recorded an important tectonic thermal event in Paleoproterozoic. This event was probably related to collision of the East and West block,and resulted in the final assembly of the North China Craton

  10. Zircon geochronology and geochemistry of mafic xenoliths from Liaoning kimberlites: Track the early evolution of the lower crust, North China Craton

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Jianping; YU; Chunmei; LU; Fengxiang; LI; Huimin

    2004-01-01

    Mafic xenoliths from Paleozoic Fuxian kimberlites (Liaoning Province) mainly include garnet granulite, with minor pyroxene amphibolite, meta-gabbro and pyroxene syenite. The SiO2 contents of the xenoliths are from 47.3 wt% to 49.9 wt%. The granulites are mainly coarse-medium grained and reasonably with well-developed granoblastic (mostly polygonal)texture, contain the assemblage of garnet + plagioclase + pyroxene + K-feldspar ± phlogopite.The mineral assemblage of the amphibolites is plagioclase + pyroxene + amphibole ± K-feldspar,with the equilibrium temperature and pressure conditions of 744-821 ℃ and 0.76-0.88 GPa.The granulites are regarded as derivation from the lower crust depth (more than 29 km), below the amphibolites. Garnet granulites compositionally correspond to sub-alkalic basalt, and have wide ranges of Ni abundance (133-840 ppm), and Nb/Y (0.12-1.85), Nb/U (3.51-53.86) and Ta/U (0.38-2.48). The amphibolite and the syenite correspond to alkalic basalt. The Fuxian mafic xenoliths are regarded as the metamorphic product of the underplated magmas (including fractional crystallization or not) experienced the contamination with the pre-existed crustal components, and partly effected by kimberlitic magmas. The concordant ages of zircons for the gabbro (2610-2580 Ma) and the near-concordant upper intercept ages of zircons for the garnet granulite and pyroxene amphibolite (2578-2538 Ma) indicate that they are currently known as the oldest deep-seated xenoliths from the lower crust of the North China Craton. These ages recorded the formation of the united Eastern Block of the North China Craton, That is, Neoarchean (2.6-2.5 Ga) is an important continental crustal growth period of the North China Craton.The lower intercept age of the garnet granulite (1853 Ma) recorded an important tectonic thermal event in Paleoproterozoic. This event was probably related to collision of the East and West block,and resulted in the final assembly of the North China Craton

  11. Holographic microscopy in low coherence

    Science.gov (United States)

    Chmelík, Radim; Petráček, Jiří; Slabá, Michala; Kollárová, Věra; Slabý, Tomáš; Čolláková, Jana; Komrska, Jiří; Dostál, Zbyněk.; Veselý, Pavel

    2016-03-01

    Low coherence of the illumination substantially improves the quality of holographic and quantitative phase imaging (QPI) by elimination of the coherence noise and various artefacts and by improving the lateral resolution compared to the coherent holographic microscopy. Attributes of coherence-controlled holographic microscope (CCHM) designed and built as an off-axis holographic system allowing QPI within the range from complete coherent to incoherent illumination confirmed these expected advantages. Low coherence illumination also furnishes the coherence gating which constraints imaging of some spatial frequencies of an object axially thus forming an optical section in the wide sense. In this way the depth discrimination capability of the microscope is introduced at the price of restricting the axial interval of possible numerical refocusing. We describe theoretically these effects for the whole range of illumination coherence. We also show that the axial refocusing constraints can be overcome using advanced mode of imaging based on mutual lateral shift of reference and object image fields in CCHM. Lowering the spatial coherence of illumination means increasing its numerical aperture. We study how this change of the illumination geometry influences 3D objects QPI and especially the interpretation of live cells QPI in terms of the dry mass density measurement. In this way a strong dependence of the imaging process on the light coherence is demonstrated. The theoretical calculations and numerical simulations are supported by experimental data including a chance of time-lapse watching of live cells even in optically turbid milieu.

  12. Extrusão de placa escleral senil: relato de um caso Extrusion of a senile scleral plaque: A case report

    Directory of Open Access Journals (Sweden)

    Eduardo Ferrari Marback

    2000-06-01

    Full Text Available Objetivo: Relatar caso de extrusão parcial espontânea de placa de transluscência focal senil de esclera calcificada. Método: Relato de caso de mulher de 75 anos, encaminhada com suspeita de tumor conjuntival, apresentando lesão leucoplásica em esclera, localizada anteriormente à inserção do músculo reto medial do olho esquerdo causando sensação de corpo estranho; instituindo-se tratamento por exérese e enxerto escleral. O exame histopatológico revelou tecido conjuntivo fibroso com calcificação. Conclusão: A extrusão de placa de transluscência senil de esclera deve ser considerada no diagnóstico diferencial dos tumores epibulbares.Purpose: To present a case of spontaneous extrusion of a calcified plaque of scleral focal senile translucency. Methods: Case report of a 75-year-old female, referred because of a epibulbar tumor suspicion. She complained of foreign body sensation and had a white scleral plaque in front of the left medial rectus insertion. The lesion was exci-sed and a scleral graft performed. The histologic examination showed fibrous connective tissue, with calcification. Conclusion: Spontaneous extrusion of senile scleral plaques should be included in the differential diagnosis of epibulbar tumors.

  13. Sheets of branched poly(lactic acid) obtained by one step reactive extrusion calendering process: Melt rheology analysis

    OpenAIRE

    Cailloux, J.; Santana, O.O.; E. Franco-Urquiza; Bou, J. J.; F. Carrasco; J. Gamez-Perez; M. L. Maspoch

    2013-01-01

    One-step reactive extrusion-calendering process (REX-Calendering) was used in order to obtain sheets of 1mm from two PD,L-LA extrusion grades modified with a styrene-acrylic multifunctional oligomeric agent. In a preliminary internal mixer study, torque versus time was monitored in order to determine chain extender ratios and reaction time. Once all parameters were optimized, reactive extrusion experiments were performed. Independently of the processing method employed, under the same pro...

  14. Topological Properties of Spatial Coherence Function

    Institute of Scientific and Technical Information of China (English)

    REN Ji-Rong; ZHU Tao; DUAN Yi-Shi

    2008-01-01

    The topological properties of the spatial coherence function are investigated rigorously.The phase singular structures(coherence vortices)of coherence function can be naturally deduced from the topological current,which is an abstract mathematical object studied previously.We find that coherence vortices are characterized by the Hopf index and Brouwer degree in topology.The coherence flux quantization and the linking of the closed coherence vortices are also studied from the topological properties of the spatial coherence function.

  15. A simplified model for V-ATPase H+ extrusion.

    Science.gov (United States)

    Luo, Chuan; Clark, John W; Heming, Thomas A; Bidani, Akhil

    2004-12-01

    An analytical model of V-type H+-translocating ATPase (V-ATPase) was developed based on an approximation to the mechanochemical model of Grabe et al. (Biophys. J., pp. 2798-2813, vol. 78, 2000). Grabe's work utilizes structural information and physiological assumptions to construct a detailed mechanochemical model of the V-ATPase. Due to the complexity of their model, it does not give a readily usable mathematical expression for the V-ATPase current. Based on their analysis of the structure of the proton pump, we develop a two-compartment model of the V-ATPase, which contains a membrane "half-channel" for proton translocation separated by a hydrophilic strip and a hydrophobic wall from the cytoplasm. Using the Langevin equation to describe proton transport across the membrane, we simplify the model based on their assumptions on the molecular structure of the pump and arrive at a general form of solution to the proton pump flux driven by ATP hydrolysis based on assumptions on the physiological properties of the strip and the wall, as well as the two fluid compartments. In this process of simplification, we explicitly relate V-ATPase structure, stoichiometry, pump efficiency, and ATP hydrolysis energy to the active pump current. The simplified model is used to provide model-generated approximations to measured data from a variety of laboratories. In addition, it provides a very compact characterization of V-ATPase, which can be used as a proton extruder in a variety of different cell membranes, as well as in the membranes of intracellular organelles. Index Terms-Electrophysiology, mechanochemstry, molecular motors, proton extrusion

  16. Assisted distillation of quantum coherence

    CERN Document Server

    Chitambar, E; Rana, S; Bera, M N; Adesso, G; Lewenstein, M

    2015-01-01

    We introduce and study the task of assisted coherence distillation. This task arises naturally in bipartite systems where both parties work together to generate the maximal possible coherence on one of the subsystems. Only incoherent operations are allowed on the target system while general local quantum operations are permitted on the other, an operational paradigm that we call local quantum-incoherent operations and classical communication (LQICC). We show that the asymptotic rate of assisted coherence distillation for pure states is equal to the coherence of assistance, a direct analog of the entanglement of assistance, whose properties we characterize. Our findings imply a novel interpretation of the von Neumann entropy: it quantifies the maximum amount of extra quantum coherence a system can gain when receiving assistance from a collaborative party. Our results are generalized to coherence localization in a multipartite setting and possible applications are discussed.

  17. Volitional Control of Neuromagnetic Coherence

    Directory of Open Access Journals (Sweden)

    Matthew D Sacchet

    2012-12-01

    Full Text Available Coherence of neural activity between circumscribed brain regions has been implicated as an indicator of intracerebral communication in various cognitive processes. While neural activity can be volitionally controlled with neurofeedback, the volitional control of coherence has not yet been explored. Learned volitional control of coherence could elucidate mechanisms of associations between cortical areas and its cognitive correlates and may have clinical implications. Neural coherence may also provide a signal for brain-computer interfaces (BCI. In the present study we used the Weighted Overlapping Segment Averaging (WOSA method to assess coherence between bilateral magnetoencephalograph (MEG sensors during voluntary digit movement as a basis for BCI control. Participants controlled an onscreen cursor, with a success rate of 124 of 180 (68.9%, sign-test p < 0.001 and 84 out of 100 (84%, sign-test p < 0.001. The present findings suggest that neural coherence may be volitionally controlled and may have specific behavioral correlates.

  18. Quantum Coherence as a Resource

    CERN Document Server

    Streltsov, Alexander; Plenio, Martin B

    2016-01-01

    The coherent superposition of states, in combination with energy quantization, represents one of the most fundamental features that mark the departure of quantum mechanics from the classical realm. Quantum coherence in many-body systems embodies the essence of entanglement and is an essential ingredient for a plethora of physical phenomena in quantum optics, quantum information, solid state physics, and nanoscale thermodynamics. In recent years, research on the presence and functional role of quantum coherence in biological systems has also attracted a considerable interest. Despite the fundamental importance of quantum coherence, the development of a rigorous theory of quantum coherence as a physical resource has only been initiated recently. In this Colloquium we discuss and review the development of this rapidly growing research field that encompasses the characterization, quantification, manipulation, dynamical evolution, and operational application of quantum coherence.

  19. Coherent optics in students' laboratories

    Science.gov (United States)

    Senderáková, Dagmar; Mesaros, Vladimir; Drzik, Milan

    2014-12-01

    Lasers provide us with unique kind of light - coherent light. Besides being the keystone of historical interferometric measuring methods, coherent waves, now accessible in a very easy way, become a base of new optical measuring and information processing methods. Moreover, holographic recording seems today to have become a common term, even among common, not especially optically educated people. The presentation deals with our attempt to take our students' interest in the coherence of light and getting them familiar with the phenomenon, indeed.

  20. Review of Entangled Coherent States

    CERN Document Server

    Sanders, Barry C

    2011-01-01

    We review entangled coherent state research since its first implicit use in 1967 to the present. Entangled coherent states are important to quantum superselection principles, quantum information processing, quantum optics, and mathematical physics. Despite their inherent fragility they have produced in a conditional propagating-wave quantum optics realization. Fundamentally the states are intriguing because they are entanglements of the coherent states, which are in a sense the most classical of all states of a dynamical system.

  1. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  2. Diffraction coherence in optics

    CERN Document Server

    Françon, M; Green, L L

    2013-01-01

    Diffraction: Coherence in Optics presents a detailed account of the course on Fraunhofer diffraction phenomena, studied at the Faculty of Science in Paris. The publication first elaborates on Huygens' principle and diffraction phenomena for a monochromatic point source and diffraction by an aperture of simple form. Discussions focus on diffraction at infinity and at a finite distance, simplified expressions for the field, calculation of the path difference, diffraction by a rectangular aperture, narrow slit, and circular aperture, and distribution of luminous flux in the airy spot. The book th

  3. Optical coherence refractometry.

    Science.gov (United States)

    Tomlins, Peter H; Woolliams, Peter; Hart, Christian; Beaumont, Andrew; Tedaldi, Matthew

    2008-10-01

    We introduce a novel approach to refractometry using a low coherence interferometer at multiple angles of incidence. We show that for plane parallel samples it is possible to measure their phase refractive index rather than the group index that is usually measured by interferometric methods. This is a significant development because it enables bulk refractive index measurement of scattering and soft samples, not relying on surface measurements that can be prone to error. Our technique is also noncontact and compatible with in situ refractive index measurements. Here, we demonstrate this new technique on a pure silica test piece and a highly scattering resin slab, comparing the results with standard critical angle refractometry.

  4. Objective Eulerian Coherent Structures

    CERN Document Server

    Serra, M

    2015-01-01

    We define objective Eulerian Coherent Structures (OECSs) in two-dimensional, non-autonomous dynamical systems as instantaneously most influential material curves. Specifically, OECSs are stationary curves of the averaged instantaneous material stretching-rate or material shearing-rate functionals. From these objective (frame-invariant) variational principles, we obtain explicit differential equations for hyperbolic, elliptic and parabolic OECSs. As illustration, we compute OECSs in an unsteady ocean velocity data set. In comparison to structures suggested by other common Eulerian diagnostic tools, we find OECSs to be the correct short-term cores of observed trajectory deformation patterns.

  5. Coherent laser beam combining

    CERN Document Server

    Brignon, Arnaud

    2013-01-01

    Recently, the improvement of diode pumping in solid state lasers and the development of double clad fiber lasers have allowed to maintain excellent laser beam quality with single mode fibers. However, the fiber output power if often limited below a power damage threshold. Coherent laser beam combining (CLBC) brings a solution to these limitations by identifying the most efficient architectures and allowing for excellent spectral and spatial quality. This knowledge will become critical for the design of the next generation high-power lasers and is of major interest to many industrial, environme

  6. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten;

    2016-01-01

    in general practice, outpatient clinics, home care and physiotherapy. Furthermore, field observations are conducted in general practice, home care and rehabilitation settings. Perspectives Knowledge about the practice of cross-sectorial collaboration is crucial to the future planning of collaborating...... initiatives in health care. The present study will generate new, valuable insight into the areas of cross-sectorial health care collaboration. Our findings may facilitate change in current practice and improve the quality and coherence in patient pathways of EPCD. The findings of this study will be useful...

  7. Coherent signal processing in optical coherence tomography

    Science.gov (United States)

    Kulkarni, Manish Dinkarrao

    1999-09-01

    Optical coherence tomography (OCT) is a novel method for non-invasive sub-surface imaging of biological tissue micro-structures. OCT achieves high spatial resolution ( ~ 15 m m in three dimensions) using a fiber-optically integrated system which is suitable for application in minimally invasive diagnostics, including endoscopy. OCT uses an optical heterodyne detection technique based on white light interferometry. Therefore extremely faint reflections ( ~ 10 fW) are routinely detected with high spatial localization. The goal of this thesis is twofold. The first is to present a theoretical model for describing image formation in OCT, and attempt to enhance the current level of understanding of this new modality. The second objective is to present signal processing methods for improving OCT image quality. We present deconvolution algorithms to obtain improved longitudinal resolution in OCT. This technique may be implemented without increasing system complexity as compared to current clinical OCT systems. Since the spectrum of the light backscattered from bio-scatterers is closely associated with ultrastructural variations in tissue, we propose a new technique for measuring spectra as a function of depth. This advance may assist OCT in differentiating various tissue types and detecting abnormalities within a tissue. In addition to depth resolved spectroscopy, Doppler processing of OCT signals can also improve OCT image contrast. We present a new technique, termed color Doppler OCT (CDOCT). It is an innovative extension of OCT for performing spatially localized optical Doppler velocimetry. Micron-resolution imaging of blood flow in sub-surface vessels in living tissue using CDOCT is demonstrated. The fundamental issues regarding the trade- off between the velocity estimation precision and image acquisition rate are presented. We also present novel algorithms for high accuracy velocity estimation. In many blood vessels velocities tend to be on the order of a few cm

  8. Perspective: Quantum or classical coherence?

    Science.gov (United States)

    Miller, William H

    2012-06-07

    Some coherence effects in chemical dynamics are described correctly by classical mechanics, while others only appear in a quantum treatment--and when these are observed experimentally it is not always immediately obvious whether their origin is classical or quantum. Semiclassical theory provides a systematic way of adding quantum coherence to classical molecular dynamics and thus provides a useful way to distinguish between classical and quantum coherence. Several examples are discussed which illustrate both cases. Particularly interesting is the situation with electronically non-adiabatic processes, where sometimes whether the coherence effects are classical or quantum depends on what specific aspects of the process are observed.

  9. Coherent states on the circle

    CERN Document Server

    Chadzitaskos, G; Tolar, J

    2011-01-01

    We present a possible construction of coherent states on the unit circle as configuration space. In our approach the phase space is the product Z x S^1. Because of the duality of canonical coordinates and momenta, i.e. the angular variable and the integers, this formulation can also be interpreted as coherent states over an infinite periodic chain. For the construction we use the analogy with our quantization over a finite periodic chain where the phase space was Z_M x Z_M. Properties of the coherent states constructed in this way are studied and the coherent states are shown to satisfy the resolution of unity.

  10. Converting Coherence to Quantum Correlations.

    Science.gov (United States)

    Ma, Jiajun; Yadin, Benjamin; Girolami, Davide; Vedral, Vlatko; Gu, Mile

    2016-04-22

    Recent results in quantum information theory characterize quantum coherence in the context of resource theories. Here, we study the relation between quantum coherence and quantum discord, a kind of quantum correlation which appears even in nonentangled states. We prove that the creation of quantum discord with multipartite incoherent operations is bounded by the amount of quantum coherence consumed in its subsystems during the process. We show how the interplay between quantum coherence consumption and creation of quantum discord works in the preparation of multipartite quantum correlated states and in the model of deterministic quantum computation with one qubit.

  11. Structural analysis and implicit 3D modelling of high-grade host rocks to the Venetia kimberlite diatremes, Central Zone, Limpopo Belt, South Africa

    Science.gov (United States)

    Basson, I. J.; Creus, P. K.; Anthonissen, C. J.; Stoch, B.; Ekkerd, J.

    2016-05-01

    The Beit Bridge Complex of the Central Zone (CZ) of the Limpopo Belt hosts the 519 ± 6 Ma Venetia kimberlite diatremes. Deformed shelf- or platform-type supracrustal sequences include the Mount Dowe, Malala Drift and Gumbu Groups, comprising quartzofeldspathic units, biotite-bearing gneiss, quartzite, metapelite, metacalcsilicate and ortho- and para-amphibolite. Previous studies define tectonometamorphic events at 3.3-3.1 Ga, 2.7-2.5 Ga and 2.04 Ga. Detailed structural mapping over 10 years highlights four deformation events at Venetia. Rules-based implicit 3D modelling in Leapfrog Geo™ provides an unprecedented insight into CZ ductile deformation and sheath folding. D1 juxtaposed gneisses against metasediments. D2 produced a pervasive axial planar foliation (S2) to isoclinal F2 folds. Sheared lithological contacts and S2 were refolded into regional, open, predominantly southward-verging, E-W trending F3 folds. Intrusion of a hornblendite protolith occurred at high angles to incipient S2. Constrictional-prolate D4 shows moderately NE-plunging azimuths defined by elongated hornblendite lenses, andalusite crystals in metapelite, crenulations in fuchsitic quartzite and sheath folding. D4 overlaps with a: 1) 2.03-2.01 Ga regional M3 metamorphic overprint; b) transpressional deformation at 2.2-1.9 Ga and c) 2.03 Ga transpressional, dextral shearing and thrusting around the CZ and d) formation of the Avoca, Bellavue and Baklykraal sheath folds and parallel lineations.

  12. Smooth Particle Hydrodynamics Simulation of Micro-Cup-Extrusion Using a Graphit-ic Coating

    Directory of Open Access Journals (Sweden)

    Li Shi-Cheng

    2014-01-01

    Full Text Available Microextrusion is becoming increasingly important for the manufacturing of microcomponents. However, this reduction in scale to a microlevel means that the influence of friction and the need for suitable lubrication are greatly increased. This study therefore looks at the use of a low-friction and highly wear resistant Graphit-ic coating on the mold-forming section of a microextrusion mold, this coating being applied by a closed-field unbalanced magnetron sputter ion plating technique. A microcup of CuZn33 brass alloy was then extruded, with a wall thickness of 0.45 mm, outside diameter of 2.9 mm, and an internal diameter of 2 mm. The experimental results in which extrusion uses the mold coating with Graphit-ic film are compared against the experimental results in which extrusion uses the mold uncoating with Graphit-ic film. This showed that the load was decreased a lot and the self-lubricating solid coating facilitates a smooth extrusion process. As the extrusion rate was quite high, smoothed particle hydrodynamics method simulations of the extrusion process were conducted, these being then compared with the experimental results. These result showed that the SPH simulation can be applied to show the deformation of materials and predict the load trend.

  13. High meniscal slope angle as a risk factor for meniscal allograft extrusion.

    Science.gov (United States)

    Łuczkiewicz, P; Daszkiewicz, K; Chróścielewski, J; Witkowski, W; Kuik, L

    2017-04-01

    A meniscal graft extrusion is still an unresolved problem that affects most patients after a meniscal transplantation. Despite the advances in surgical techniques, together with the improved methods for a meniscal allograft sizing, success is only observed in up to 75% of patients after they experience a meniscal allograft transplantation. Because a meniscal extrusion is associated with a cartilage deterioration and the progression of osteoarthritis there is a great interest in how to prevent this phenomenon. The crucial factor for the minimisation of a meniscal allograft extrusion is by perfectly matching the implant. Most methods for a meniscal allograft sizing only focus on assessing the length and the width of the meniscus. Even though there is some evidence that there is a relationship between the shape of the meniscus in a cross-sectional plane and the meniscal extrusion, any of the planning methods do not take this factor into consideration. Although there is a large variability of meniscus shapes in cross-section, we hypothesise that by taking the meniscal slope into account during surgical planning, as well as performing the correct adjustments of this particular parameter, we can diminish the risk of a meniscal allograft extrusion. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effect of die shape on the metal flow pattern during direct extrusion process

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, N.; Solomon, I.

    2010-07-01

    The geometric shape of the tools is the main factor by which an optimum technological process can be developed. In the case of extrusion process the strain distribution and other important variables that influence material structure, such as hydrostatic stress, are strongly dependent on the geometry of the die. Careful design of the extrusion die profile can therefore control the product structure and can be used to minimise the amount of inhomogeneity imparted into the product. A possibility to minimise the amount of product inhomogeneity is the using of a flat die with a fillet radius in front to the bearing surface with leads to a minimum dead zone and consequently to a minimum friction at billet-container interface. In the case of aluminium alloy type 2024, for an extrusion ratio of R=8.5, good results were obtained with a fillet radius of 3.0 mm. The experimental data have been used for the finite element numerical simulation of the extrusion process. The data obtained by numerical simulation with FORGE2 programme confirm the theoretical and experimental outcomes. The aim of this paper is to study the influence of such flat die on the material flow during direct extrusion process and consequently on extruded product microstructure and mechanical properties. (Author).

  15. Die Radius Affecting Sheet Metal Extrusion Quality for Fine Blanking Process

    Directory of Open Access Journals (Sweden)

    Chatkaew Suriyapha

    2010-01-01

    Full Text Available Problem statement: Sheet metal extrusion is a process in which the punch penetrates one surface of the sheet metal material to cause it to extrude and flow toward the outlet of the die. Therefore, the process can invent different thickness of sheet metal work piece. From these advantages on the sheet metal extrusion, nowadays, it is generally used in many manufacturing of industrial elements fields. The Sheet Metal Extrusions in Fine Blanking (SME-FB advantages, over a conventional extrusion, are possible due to a blank holder force, a counterpunch force and a large die radius. However, the selection on those parameter values affects on the material flow and the surface quality on the extrusion parts also. Namely, it causes the crack surface and shrinkage failure which are the general problems in the SME-FB. Approach: Objective of this research was to study the effect of die radius on the SME-FB surface which investigated the formation of the failure defection with respect to the several die radiuses by using the Finite Element Method (FEM. Results: From the results, it indicated that applying the small die radius caused the material flow difficult resulting in the decreasing of smooth surface. Vice versa, in the case of large die radius, the material flow easy is resulting in the increasing of smooth surface. Conclusion: The FEM simulation results of a larger die radius will cause the residual stress at work piece.

  16. Pharmaceutical approaches to preparing pelletized dosage forms using the extrusion-spheronization process.

    Science.gov (United States)

    Trivedi, Namrata R; Rajan, Maria Gerald; Johnson, James R; Shukla, Atul J

    2007-01-01

    Pelletized dosage forms date back to the 1950s, when the first product was introduced to the market. Since then, these dosage forms have gained considerable popularity because of their distinct advantages, such as ease of capsule filling because of better flow properties of the spherical pellets; enhancement of drug dissolution; ease of coating; sustained, controlled, or site-specific delivery of the drug from coated pellets; uniform packing; even distribution in the GI tract; and less GI irritation. Pelletized dosage forms can be prepared by a number of techniques, including drug layering on nonpareil sugar or microcrystalline cellulose beads, spray drying, spray congealing, rotogranulation, hot-melt extrusion, and spheronization of low melting materials or extrusion-spheronization of a wet mass. This review discusses recent developments in the pharmaceutical approaches that have been used to prepare pelletized dosage forms using the extrusion-spheronization process over the last decade. The review is divided into three parts: the first part discusses the extrusion-spheronization process, the second part discusses the effect of varying formulation and process parameters on the properties of the pellets, and the last part discusses the different approaches that have been used to prepare pelletized dosage forms using the extrusion-spheronization process.

  17. FEM Analysis of Force Parameters During Hot Extrusion Expanding and Reducing Tube Process

    Institute of Scientific and Technical Information of China (English)

    WANG Fenghui; JIAO Anyuan; LI Haidong; GAO Xingqi; YANG Siqiong

    2006-01-01

    In this paper, based on the plastic forming large deformation theory and thermodynamic elastic-plastic FEM, the process of expanding and reducing tube was analyzed by using nonlinear finite element software MARC. The coupled thermal-mechanical models for the thermal-extrusion tube process were established, and the dynamic simulation to them was carried out. By the study on 3D deformation regulation of the thermal-extrusion tube, the distribution of stress,strain and the curves between the force of extrusion and the distance were obtained. As a result, with only a small quantity of necessary experiments, the select of the schemes and parameters can conveniently be performed in the computers. So, not only large numbers of experiments can be avoided, but also trial-manufacture period is consumedly shortened and some costs may be saved. In addition, in order to validate our numerical calculation, an experiment of the tube made of 20 steel is presented in this paper. Good agreement is shown between measured and predicted results of the theoretical analysis model. The study provides a scientific basis for parametric optimizations of the thermal extrusion expanding and reducing tube production equipment. At the same time, the method used in the present paper has important referential value for studying the similar thermal extrusion parts.

  18. Comparison of Murine Cervicovaginal Infection by Chlamydial Strains: Identification of Extrusions Shed In vivo

    Science.gov (United States)

    Shaw, Jennifer H.; Behar, Amanda R.; Snider, Timothy A.; Allen, Noah A.; Lutter, Erika I.

    2017-01-01

    Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections (STIs) and preventable blindness. Untreated, asymptomatic infection as well as frequent re-infection are common and may drive pelvic inflammatory disease, ectopic pregnancy, and infertility. In vivo models of chlamydial infection continue to be instrumental in progress toward a vaccine and further elucidating the pathogenesis of this intracellular bacterium, however significant gaps in our understanding remain. Chlamydial host cell exit occurs via two mechanisms, lysis and extrusion, although the latter has yet to be reported in vivo and its biological role is unclear. The objective of this study was to investigate whether chlamydial extrusions are shed in vivo following infection with multiple strains of Chlamydia. We utilized an established C3H/HeJ murine cervicovaginal infection model with C. trachomatis serovars D and L2 and the Chlamydia muridarum strain MoPn to monitor the (i) time course of infection and mode of host cell exit, (ii) mucosal and systemic immune response to infection, and (iii) gross and histopathology following clearance of active infection. The key finding herein is the first identification of chlamydial extrusions shed from host cells in an in vivo model. Extrusions, a recently appreciated mode of host cell exit and potential means of dissemination, had been previously observed solely in vitro. The results of this study demonstrate that chlamydial extrusions exist in vivo and thus warrant further investigation to determine their role in chlamydial pathogenesis. PMID:28217555

  19. Optimization of pneumatic sheet extrusion of whole wheat flour poory dough using response surface methodology.

    Science.gov (United States)

    Murthy, K Venkatesh; Sudha, M L; Ravi, R; Raghavarao, K S M S

    2015-07-01

    Pneumatic extrusion of whole wheat flour dough is a challenge in the preparation of Poory. In the present study, the pneumatic extrusion process variables (pneumatic pressure, rate of extrusion) and quality of deep fried product (oil uptake, frying time, puffed height) was evaluated to get Poory of maximum overall sensory quality, minimum shear and minimum oil uptake. These parameters depend on the moisture content of wheat dough. Response surface methodology was demonstrated to be an efficient tool for the optimization of process parameters of pneumatic extrusion. The results indicated that extrusion pressure ranging from 3 ~ 6 × 10(5) Pa for the whole wheat flour dough with added moisture of 56 ~ 60 % was found to give a uniform rate of extruded sheet. It was observed that submerged frying time for the extruded dough sheet was in the range of 35 ~ 40 s, with the temperature of the vegetable oil to be in the range of 180 ~ 185 °C. Oil uptake during frying was about 12 ± 1 % and the textural shear force was found to be 9.9 N with an overall sensory score of 7.2 ± 0.5 on nine point scale. The experimental errors for all attributes were non-significant (p > 0.05) and thus optimum variables predicted by the model are found suitable.

  20. Poly(ether ester) Ionomers as Water-Soluble Polymers for Material Extrusion Additive Manufacturing Processes.

    Science.gov (United States)

    Pekkanen, Allison M; Zawaski, Callie; Stevenson, André T; Dickerman, Ross; Whittington, Abby R; Williams, Christopher B; Long, Timothy E

    2017-04-12

    Water-soluble polymers as sacrificial supports for additive manufacturing (AM) facilitate complex features in printed objects. Few water-soluble polymers beyond poly(vinyl alcohol) enable material extrusion AM. In this work, charged poly(ether ester)s with tailored rheological and mechanical properties serve as novel materials for extrusion-based AM at low temperatures. Melt transesterification of poly(ethylene glycol) (PEG, 8k) and dimethyl 5-sulfoisophthalate afforded poly(ether ester)s of sufficient molecular weight to impart mechanical integrity. Quantitative ion exchange provided a library of poly(ether ester)s with varying counterions, including both monovalent and divalent cations. Dynamic mechanical and tensile analysis revealed an insignificant difference in mechanical properties for these polymers below the melting temperature, suggesting an insignificant change in final part properties. Rheological analysis, however, revealed the advantageous effect of divalent countercations (Ca(2+), Mg(2+), and Zn(2+)) in the melt state and exhibited an increase in viscosity of two orders of magnitude. Furthermore, time-temperature superposition identified an elevation in modulus, melt viscosity, and flow activation energy, suggesting intramolecular interactions between polymer chains and a higher apparent molecular weight. In particular, extrusion of poly(PEG8k-co-CaSIP) revealed vast opportunities for extrusion AM of well-defined parts. The unique melt rheological properties highlighted these poly(ether ester) ionomers as ideal candidates for low-temperature material extrusion additive manufacturing of water-soluble parts.

  1. Effect of extrusion rate on morphology of Kaolin/PolyEtherSulfone (PESf) membrane precursor

    Science.gov (United States)

    Misaran, M. S.; Sarbatly, R.; Bono, A.; Rahman, M. M.

    2016-11-01

    This study aims to investigate the influence of apparent viscosity induced by spinneret geometry and extrusion rate on morphology of Kaolin/PESf hollow fiber membranes. Different extrusion rates at two different rheology properties were introduced on a straight and conical spinneret resulting in various shear rates. The hollow fiber membrane precursors were spun using the wet spinning method to decouple the effect of shear and elongation stress due to gravity stretched drawing. The morphology of the spun hollow fiber was observed under Scanning Electron Microscope (SEM) and the overall porosity were measured using mercury intrusion porosimeter. Shear rate and apparent viscosity at the tip of the spinneret annulus were simulated using a computational fluid dynamics package; solidworks floworks. Simulation data shows that extrusion rate increment increases the shear rate at the spinneret wall which in turn reduce the apparent viscosity; consistent with a non Newtonian shear thinning fluid behavior. Thus, the outer finger-like region grows as the shear rate increases. Also, overall porosity of hollow fiber membrane decreases with extrusion rate increment which is caused by better molecular orientation; resulting in denser hollow fiber membrane. Thin outer finger-like region is achieved at low shear experience of 109.55 s-1 via a straight spinneret. Increasing the extrusion rate; thus shear rate will cause outer finger-like region growth which is not desirable in a separation process.

  2. Fermionic coherent states

    Science.gov (United States)

    Combescure, Monique; Robert, Didier

    2012-06-01

    The aim of this paper is to give a self-contained and unified presentation of a fermionic coherent state theory with the necessary mathematical details, discussing their definition, properties and some applications. After defining Grassmann algebras, it is possible to get a classical analog for the fermionic degrees of freedom in a quantum system. Following the basic work of Berezin (1966 The Method of Second Quantization (New York: Academic); 1987 Introduction to Superanalysis (Dordrecht: Reidel Publishing Company)), we show that we can compute with Grassmann numbers as we do with complex numbers: derivation, integration, Fourier transform. After that we show that we have quantization formulas for fermionic observables. In particular, there exists a Moyal product formula. As an application, we consider explicit computations for propagators with quadratic Hamiltonians in annihilation and creation operators. We prove a Mehler formula for the propagator and Mehlig-Wilkinson-type formulas for the covariant and contravariant symbols of ‘metaplectic’ transformations for fermionic states. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’.

  3. Coherence for weak units

    CERN Document Server

    Joyal, André

    2009-01-01

    We define weak units in a semi-monoidal 2-category $\\CC$ as cancellable pseudo-idempotents: they are pairs $(I,\\alpha)$ where $I$ is an object such that tensoring with $I$ from either side constitutes a biequivalence of $\\CC$, and $\\alpha: I \\tensor I \\to I$ is an equivalence in $\\CC$. We show that this notion of weak unit has coherence built in: Theorem A: $\\alpha$ has a canonical associator 2-cell, which automatically satisfies the pentagon equation. Theorem B: every morphism of weak units is automatically compatible with those associators. Theorem C: the 2-category of weak units is contractible if non-empty. Finally we show (Theorem E) that the notion of weak unit is equivalent to the notion obtained from the definition of tricategory: $\\alpha$ alone induces the whole family of left and right maps (indexed by the objects), as well as the whole family of Kelly 2-cells (one for each pair of objects), satisfying the relevant coherence axioms.

  4. Improvement of mechanical properties and corrosion resistance of biodegradable Mg-Nd-Zn-Zr alloys by double extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaobo, E-mail: xbxbzhang2003@163.com [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China); Wang, Zhangzhong [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China); Yuan, Guangyin [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai, 200240 (China); Xue, Yajun [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China)

    2012-08-01

    Highlights: Black-Right-Pointing-Pointer Microstructure of Mg-Nd-Zn-Zr alloys was refined and homogenized by double extrusion process. Black-Right-Pointing-Pointer The mechanical properties of the alloys were significantly enhanced by double extrusion. Black-Right-Pointing-Pointer The biocorrosion resistance of the alloys was improved by double extrusion. - Abstract: Mg-Nd-Zn-Zr alloy is a novel and promising biodegradable magnesium alloy due to good biocompatibility, desired uniform corrosion mode and outstanding corrosion resistance in simulated body fluid (SBF). However, the corrosion resistance and mechanical properties should be improved to meet the requirement of the biodegradable implants, such as plates, screws and cardiovascular stents. In the present study, double extrusion process was adopted to refine microstructure and improve mechanical properties of Mg-2.25Nd-0.11Zn-0.43Zr and Mg-2.70Nd-0.20Zn-0.41Zr alloys. The corrosion resistance of the alloys after double extrusion was also studied. The results show that the microstructure of the alloys under double extrusion becomes much finer and more homogeneous than those under once extrusion. The yield strength, ultimate tensile strength and elongation of the alloys under double extrusion are over 270 MPa, 300 MPa and 32%, respectively, indicating that outstanding mechanical properties of Mg-Nd-Zn-Zr alloy can be obtained by double extrusion. The results of immersion experiment and electrochemical measurements in SBF show that the corrosion resistance of Alloy 1 and Alloy 2 under double extrusion was increased by 7% and 8% respectively compared with those under just once extrusion.

  5. Studies in reactive extrusion processing of biodegradable polymeric materials

    Science.gov (United States)

    Balakrishnan, Sunder

    Various reaction chemistries such as Polymerization, Polymer cross-linking and Reactive grafting were investigated in twin-screw extruders. Poly (1,4-dioxan-2-one) (PPDX) was manufactured in melt by the continuous polymerization of 1,4-dioxan-2-one (PDX) monomer in a twin-screw extruder using Aluminum tri-sec butoxide (ATSB) initiator. Good and accurate control over molecular weight was obtained by controlling the ratio of monomer to initiator. A screw configuration consisting of only conveying elements was used for the polymerization. The polymerization reaction was characterized by a monomer-polymer dynamic equilibrium, above the melting temperature of the polymer, limiting the equilibrium conversion to 78-percent. Near complete (˜100-percent) conversion was obtained on co-polymerizing PDX monomer with a few mol-percent (around 8-percent) Caprolactone (CL) monomer in a twin-screw extruder using ATSB initiator. The co-polymers exhibited improved thermal stability with reduction in glass transition temperature. The extruder was modeled as an Axial Dispersed Plug Flow Reactor for the polymerization of CL monomer using Residence Time Distribution (RTD) Analysis. The model provided a good fit to the experimental RTD and conversion data. Aliphatic and aliphatic-aromatic co-polyesters, namely Polycaprolactone (PCL) and Poly butylenes (adipate-co-terephthalate) (Ecoflex) were cross-linked in a twin-screw extruder using radical initiator to form micro-gel reinforced biodegradable polyesters. Cross-linked Ecoflex was further extrusion blended with talc to form blends suitable to be blown into films. A screw configuration consisting of conveying and kneading elements was found to be effective in dispersion of the talc particles (5--10 microns) in the polyester matrix. While the rates of crystallization increased for the talc filled polyester blends, overall crystallinity reduced. Mechanical, tear and puncture properties of films made using the talc filled polyester blends

  6. Seismic wave propagation through an extrusive basalt sequence

    Science.gov (United States)

    Sanford, Oliver; Hobbs, Richard; Brown, Richard; Schofield, Nick

    2016-04-01

    Layers of basalt flows within sedimentary successions (e.g. in the Faeroe-Shetland Basin) cause complex scattering and attenuation of seismic waves during seismic exploration surveys. Extrusive basaltic sequences are highly heterogeneous and contain strong impedance contrasts between higher velocity crystalline flow cores (˜6 km s-1) and the lower velocity fragmented and weathered flow crusts (3-4 km s-1). Typically, the refracted wave from the basaltic layer is used to build a velocity model by tomography. This velocity model is then used to aid processing of the reflection data where direct determination of velocity is ambiguous, or as a starting point for full waveform inversion, for example. The model may also be used as part of assessing drilling risk of potential wells, as it is believed to constrain the total thickness of the sequence. In heterogeneous media, where the scatter size is of the order of the seismic wavelength or larger, scattering preferentially traps the seismic energy in the low velocity regions. This causes a build-up of energy that is guided along the low velocity layers. This has implications for the interpretation of the observed first arrival of the seismic wave, which may be a biased towards the low velocity regions. This will then lead to an underestimate of the velocity structure and hence the thickness of the basalt, with implications for the drilling of wells hoping to penetrate through the base of the basalts in search of hydrocarbons. Using 2-D acoustic finite difference modelling of the guided wave through a simple layered basalt sequence, we consider the relative importance of different parameters of the basalt on the seismic energy propagating through the layers. These include the proportion of high to low velocity material, the number of layers, their thickness and the roughness of the interfaces between the layers. We observe a non-linear relationship between the ratio of high to low velocity layers and the apparent velocity

  7. Co-Extrusion: Advanced Manufacturing for Energy Devices

    Energy Technology Data Exchange (ETDEWEB)

    Cobb, Corie Lynn [PARC, Palo Alto, CA (United States)

    2016-11-18

    The development of mass markets for large-format batteries, including electric vehicles (EVs) and grid support, depends on both cost reductions and performance enhancements to improve their economic viability. Palo Alto Research Center (PARC) has developed a multi-material, advanced manufacturing process called co-extrusion (CoEx) to remove multiple steps in a conventional battery coating process with the potential to simultaneously increase battery energy and power density. CoEx can revolutionize battery manufacturing across most chemistries, significantly lowering end-product cost and shifting the underlying economics to make EVs and other battery applications a reality. PARC’s scale-up of CoEx for electric vehicle (EV) batteries builds on a solid base of experience in applying CoEx to solar cell manufacturing, deposition of viscous ceramic pastes, and Li-ion battery chemistries. In the solar application, CoEx has been deployed commercially at production scale where multi-channel CoEx printheads are used to print viscous silver gridline pastes at full production speeds (>40 ft/min). This operational scale-up provided invaluable experience with the nuances of speed, yield, and maintenance inherent in taking a new technology to the factory floor. PARC has leveraged this experience, adapting the CoEx process for Lithium-ion (Li-ion) battery manufacturing. To date, PARC has worked with Li-ion battery materials and structured cathodes with high-density Li-ion regions and low-density conduction regions, documenting both energy and power performance. Modeling results for a CoEx cathode show a path towards a 10-20% improvement in capacity for an EV pouch cell. Experimentally, we have realized a co-extruded battery structure with a Lithium Nickel Manganese Cobalt (NMC) cathode at print speeds equivalent to conventional roll coating processes. The heterogeneous CoEx cathode enables improved capacity in thick electrodes at higher C-rates. The proof-of-principle coin cells

  8. Development of expanded extrusion food products for an Advanced Life Support system.

    Science.gov (United States)

    Zasypkin, D V; Lee, T C

    1999-01-01

    Extrusion processing was proposed to provide texture and to expand the variety of cereal food products in an isolated Advanced Life Support (ALS) system. Rice, wheat, and soy are the baseline crops selected for growing during long-term manned space missions. A Brabender single-screw laboratory extruder (model 2003, L/D 20:1), equipped with round nozzles of various lengths, was used as a prototype of a small-size extruder. Several concepts were tested to extend the variety and improve the quality of the products, to decrease environmental loads, and to promote processing stability. These concepts include: the blending of wheat and soybean flour, the extrusion of a coarser rice flour, separation of wheat bran, and optimization of the extruder nozzle design. An optimal nozzle length has been established for the extrusion of rice flour. Bran separating was necessary to improve the quality of wheat extrudates.

  9. Effects of extrusion cooking on the chemical composition and functional properties of dry common bean powders.

    Science.gov (United States)

    Ai, Yongfeng; Cichy, Karen A; Harte, Janice B; Kelly, James D; Ng, Perry K W

    2016-11-15

    The impact of extrusion cooking on the chemical composition and functional properties of bean powders from four common bean varieties was investigated. The raw bean powders were extruded under eight different conditions, and the extrudates were then dried and ground (particle size⩽0.5mm). Compared with corresponding non-extruded (raw) bean powders (particle size⩽0.5mm), the extrusion treatments did not substantially change the protein and starch contents of the bean powders and showed inconsistent effects on the sucrose, raffinose and stachyose contents. The extrusion cooking did cause complete starch gelatinization and protein denaturation of the bean powders and thus changed their pasting properties and solvent-retention capacities. The starch digestibilities of the cooked non-extruded and cooked extruded bean powders were comparable. The extruded bean powders displayed functional properties similar to those of two commercial bean powders. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Design of Intelligent Self-Tuning GA ANFIS Temperature Controller for Plastic Extrusion System

    Directory of Open Access Journals (Sweden)

    S. Ravi

    2011-01-01

    Full Text Available This paper develops a GA ANFIS controller design method for temperature control in plastic extrusion system. Temperature control of plastic extrusion system suffers problems related to longer settling time, couple effects, large time constants, and undesirable overshoot. The system is generally nonlinear and the temperature of the plastic extrusion system may vary over a wide range of disturbances. The system is designed with three controllers. The proposed GA ANFIS controller is the most powerful approach to retrieve the adaptiveness in the case of nonlinear system. In this research the control methods are simulated using simulink. Relatively the methodology and efficiency of the proposed method are compared with those of the traditional methods and the results obtained from GA ANFIS controller give improved performance in terms of time domain specification, set point tracking, and disturbance rejection with optimum stability.

  11. A novel optical technique to characterize fiberization of textured vegetable proteins under high-moisture extrusion

    Science.gov (United States)

    Yao, Gang; Liu, Keshun; Hsieh, Fu-Hung

    2004-11-01

    There have been great interests in using twin-screw extruders under high moisture conditions to produce textured vegetable proteins. Unlike the low moisture extrusion counterpart, a product extruded under high moisture can have well-defined fiber orientation and bears a strong resemblance to muscle meat. The textural properties of such extruded products are important for consumer acceptance. In this study, we developed a novel fluorescence polarization based technique that measures the fiber formation of extruded protein products. The experimental results using our new technique showed good agreements with results obtained from visual inspection and digital imaging of the dissected samples. The new technique provides an in vivo and noninvasive approach to characterize the fiber formation of textured vegetable proteins under high moisture extrusion. It has a potential to be used as a real time monitoring tool in food extrusion studies.

  12. Characterisation of the wall-slip during extrusion of heavy-clay products

    Science.gov (United States)

    Kocserha, I.; Gömze, A. L.; Kulkov, S.; Kalatur, E.; Buyakova, S. P.; Géber, R.; Buzimov, A. Y.

    2017-01-01

    During extrusion through the extrusion die, heavy-clay compounds are usually show plug flow with extensive slip at the wall of the die. In this study, the viscosity and the thickness of the slip layer were investigated. For the examination a brick-clay from Malyi (Hungary) deposit was applied as a raw material. The clay was characterised by XRPD, BET, SEM and granulometry. As the slip layer consists of suspension of the fine clay fraction so the clay minerals content of the clay (dwater content was measured by means of rotational viscosimeter. The thickness of the slip layer was calculated from the measured viscosity and other data obtained from an earlier study with capillary rheometer. The calculated thickness value showed a tendency to reach a limit value by increasing the extrusion speed.

  13. Thermoplastic starch/polyester films: effects of extrusion process and poly (lactic acid) addition.

    Science.gov (United States)

    Shirai, Marianne Ayumi; Olivato, Juliana Bonametti; Garcia, Patrícia Salomão; Müller, Carmen Maria Olivera; Grossmann, Maria Victória Eiras; Yamashita, Fabio

    2013-10-01

    Biodegradable films were produced using the blown extrusion method from blends that contained cassava thermoplastic starch (TPS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) with two different extrusion processes. The choice of extrusion process did not have a significant effect on the mechanical properties, water vapor permeability (WVP) or viscoelasticity of the films, but the addition of PLA decreased the elongation, blow-up ratio (BUR) and opacity and increased the elastic modulus, tensile strength and viscoelastic parameters of the films. The films with 20% PLA exhibited a lower WVP due to the hydrophobic nature of this polymer. Morphological analyses revealed the incompatibility between the polymers used.

  14. Replication of micro-sized pillars in polypropylene using the extrusion coating process

    DEFF Research Database (Denmark)

    Okulova, Nastasia; Johansen, Peter; Christensen, Lars

    2017-01-01

    A recent advancement in nano-pattern replication using roll-to-roll extrusion coating (R2R-EC) shows potential for many biomimetic applications. For further development of the technique a study of the micro-replication regime is carried out. In this study a full and partial replication in polypro......A recent advancement in nano-pattern replication using roll-to-roll extrusion coating (R2R-EC) shows potential for many biomimetic applications. For further development of the technique a study of the micro-replication regime is carried out. In this study a full and partial replication...... in polypropylene (PP) of micro-sized pillars has been demonstrated using the extrusion coating process. The replication fidelity of the pillars is investigated in a systematic variation of different process parameters: the line-speed of the rolls, the extruder output, the cooling roll temperature and the pressure...

  15. Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

    Science.gov (United States)

    2017-01-01

    Herein, the benefits which extrusion can provide for the automated continuous synthesis of organic compounds are highlighted. Extrusion is a well-established technique that has a vital role in the manufacturing processes of polymers, pharmaceuticals and food products. Furthermore, this technique has recently been applied to the solvent-free continuous synthesis of co-crystals and coordination compounds including metal-organic frameworks (MOFs). To date, a vast amount of research has already been conducted into reactive extrusion (REX), particularly in the polymer industry, which in many cases has involved organic transformations, however, it has not received significant recognition for this. This review highlights these transformations and discusses how this previous research can be applied to the future of organic compound manufacture. PMID:28179950

  16. Extrusion - back to the future: Using an established technique to reform automated chemical synthesis.

    Science.gov (United States)

    Crawford, Deborah E

    2017-01-01

    Herein, the benefits which extrusion can provide for the automated continuous synthesis of organic compounds are highlighted. Extrusion is a well-established technique that has a vital role in the manufacturing processes of polymers, pharmaceuticals and food products. Furthermore, this technique has recently been applied to the solvent-free continuous synthesis of co-crystals and coordination compounds including metal-organic frameworks (MOFs). To date, a vast amount of research has already been conducted into reactive extrusion (REX), particularly in the polymer industry, which in many cases has involved organic transformations, however, it has not received significant recognition for this. This review highlights these transformations and discusses how this previous research can be applied to the future of organic compound manufacture.

  17. Robustness of a coherence vortex.

    Science.gov (United States)

    Alves, Cleberson R; Jesus-Silva, Alcenisio J; Fonseca, Eduardo J S

    2016-09-20

    We study, experimentally and theoretically, the behavior of a coherence vortex after its transmission through obstacles. Notably, we find that such a vortex survives and preserves its effective topological charge. Despite suffering changes on the modulus of the coherence function, these changes disappear during propagation.

  18. Dynamics of generalized coherent states

    CERN Document Server

    De Martino, S; Illuminati, F; De Martino, S; De Siena, S; Illuminati, F

    1995-01-01

    We show that generalized coherent states follow Schr\\"{o}dinger dynamics in time-dependent potentials. The normalized wave-packets follow a classical evolution without spreading; in turn, the Schr\\"{o}dinger potential depends on the state through the classical trajectory. This feedback mechanism with continuous dynamical re-adjustement allows the packets to remain coherent indefinetely.

  19. COHERENT LIGHT-RECORDING TECHNIQUES.

    Science.gov (United States)

    On the basis of diffraction theory, quantum-mechanics and information theory, it is shown that the principle of coherent light recording is the...mechanical, magnetic or electric approaches. Photographic coherent light recording tests were made by the dynamic sweep tests on 16 mm Recordak Micro-File

  20. COHERENT-LIGHT RECORDING TECHNIQUES.

    Science.gov (United States)

    The purpose of this report is to summarize, define and demonstrate techniques necessary for the application of coherent light to the problems of...Investigations into such areas as the coherent light source itself, modulation, deflection or scanning techniques, readout techniques and the evaluation of recording media are reported.

  1. Quantum coherence of steered states

    Science.gov (United States)

    Hu, Xueyuan; Milne, Antony; Zhang, Boyang; Fan, Heng

    2016-01-01

    Lying at the heart of quantum mechanics, coherence has recently been studied as a key resource in quantum information theory. Quantum steering, a fundamental notion originally considered by Schödinger, has also recently received much attention. When Alice and Bob share a correlated quantum system, Alice can perform a local measurement to ‘steer’ Bob’s reduced state. We introduce the maximal steered coherence as a measure describing the extent to which steering can remotely create coherence; more precisely, we find the maximal coherence of Bob’s steered state in the eigenbasis of his original reduced state, where maximization is performed over all positive-operator valued measurements for Alice. We prove that maximal steered coherence vanishes for quantum-classical states whilst reaching a maximum for pure entangled states with full Schmidt rank. Although invariant under local unitary operations, maximal steered coherence may be increased when Bob performs a channel. For a two-qubit state we find that Bob’s channel can increase maximal steered coherence if and only if it is neither unital nor semi-classical, which coincides with the condition for increasing discord. Our results show that the power of steering for coherence generation, though related to discord, is distinct from existing measures of quantum correlation.

  2. A brief review of extrusion-based tissue scaffold bio-printing.

    Science.gov (United States)

    Ning, Liqun; Chen, Xiongbiao

    2017-08-01

    Extrusion-based bio-printing has great potential as a technique for manipulating biomaterials and living cells to create three-dimensional (3D) scaffolds for damaged tissue repair and function restoration. Over the last two decades, advances in both engineering techniques and life sciences have evolved extrusion-based bio-printing from a simple technique to one able to create diverse tissue scaffolds from a wide range of biomaterials and cell types. However, the complexities associated with synthesis of materials for bio-printing and manipulation of multiple materials and cells in bio-printing pose many challenges for scaffold fabrication. This paper presents an overview of extrusion-based bio-printing for scaffold fabrication, focusing on the prior-printing considerations (such as scaffold design and materials/cell synthesis), working principles, comparison to other techniques, and to-date achievements. This paper also briefly reviews the recent development of strategies with regard to hydrogel synthesis, multi-materials/cells manipulation, and process-induced cell damage in extrusion-based bio-printing. The key issue and challenges for extrusion-based bio-printing are also identified and discussed along with recommendations for future, aimed at developing novel biomaterials and bio-printing systems, creating patterned vascular networks within scaffolds, and preserving the cell viability and functions in scaffold bio-printing. The address of these challenges will significantly enhance the capability of extrusion-based bio-printing. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Immediate release pellets with lipid binders obtained by solvent-free cold extrusion.

    Science.gov (United States)

    Krause, Julia; Thommes, Markus; Breitkreutz, Jörg

    2009-01-01

    Lipid-based drug delivery systems have spread in their use in pharmaceutical drug development. This work focuses on the use of lipid binders as alternative non-toxic extrusion aid for pellet formulations. The preparation of immediate release pellets with solid lipid binders through a solvent-free cold extrusion/spheronisation process was investigated in this study. Various binary, ternary and quaternary mixtures of powdered lipids and the model drug sodium benzoate were investigated and compared to well-known wet extrusion binders like microcrystalline cellulose and kappa-carrageenan. The cold lipid extrusion process offers multiple advantages as it is suitable for thermal sensitive as well as for hygroscopic drugs, furthermore no drying process to evaporate the solvent is needed and the process is feasible for different extruder types. Some of the developed pellets showed favourable properties like spherical shape, narrow size distribution, a high drug load of 80% sodium benzoate and a drug release of more than 90% within 40 min. The stability of drug release, which can be problematic when using lipid excipients, was sufficient for some mixtures, as storage under elevated temperatures changed the release profiles only slightly and no formulation released less than 80% within the first 60 min. A formulation with a mixture of hard fat, glycerol distearate and glycerol trimyristate showed the best results, as pellets with a low aspect ratio, narrow size distribution and complete drug release were obtained. Using appropriate mixtures of acylglycerides it becomes possible to produce pharmaceutical pellets with immediate release characteristics by cold extrusion and subsequent spheronisation. Thus, lipids are very promising alternatives to commonly used extrusion/spheronisation binders.

  4. Spectrophotometric determination of irrigant extrusion using passive ultrasonic irrigation, EndoActivator, or syringe irrigation.

    Science.gov (United States)

    Rodríguez-Figueroa, Carolina; McClanahan, Scott B; Bowles, Walter R

    2014-10-01

    Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation. One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples. Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1-3 μL) in straight roots or curved roots occurred in 10%-11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3-10 μL of NaOCl. The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Profile extrusion of wood plastic cellular composites and formulation evaluation using compression molding

    Science.gov (United States)

    Islam, Mohammad Rubyet

    Wood Plastic Composites (WPCs) have experienced a healthy growth during the last decade. However, improvement in properties is necessary to increase their utility for structural applications. The toughness of WPCs can be improved by creating a fine cellular structure while reducing the density. Extrusion processing is one of the most economical methods for profile formation. For our study, rectangular profiles were extruded using a twin-screw extrusion system with different grades of HDPE and with varying wood fibre and lubricant contents together with maleated polyethylene (MAPE) coupling agent to investigate their effects on WPC processing and mechanical properties. Work has been done to redesign the extrusion system setup to achieve smoother and stronger profiles. A guiding shaper, submerged in the water, has been designed to guide the material directly through water immediately after exiting the die; instead of passing it through a water cooled vacuum calibrator and then through water. In this way a skin was formed quickly that facilitated the production of smoother profiles. Later on chemical blowing agent (CBA) was used to generate cellular structure in the profile by the same extrusion system. CBA contents die temperatures, drawdown ratios (DDR) and wood fibre contents (WF) were varied for optimization of mechanical properties and morphology. Cell morphology and fibre alignment was characterized by a scanning electron microscope (SEM). A new compression molding system was developed to help in quick evaluation of different material formulations. This system forces the materials to flow in one direction to achieve higher net alignment of fibres during sample preparation, which is the case during profile extrusion. Operation parameters were optimized and improvements in WPC properties were observed compared to samples prepared by conventional hot press and profile extrusion.

  6. Coherence and correspondence in medicine

    Directory of Open Access Journals (Sweden)

    Thomas G. Tape

    2009-03-01

    Full Text Available Many controversies in medical science can be framed as tension between a coherence approach (which seeks logic and explanation and a correspondence approach (which emphasizes empirical correctness. In many instances, a coherence-based theory leads to an understanding of disease that is not supported by empirical evidence. Physicians and patients alike tend to favor the coherence approach even in the face of strong, contradictory correspondence evidence. Examples include the management of atrial fibrillation, treatment of acute bronchitis, and the use of Vitamin E to prevent heart disease. Despite the frequent occurrence of controversy stemming from coherence-correspondence conflicts, medical professionals are generally unaware of these terms and the philosophical traditions that underlie them. Learning about the coherence-correspondence distinction and using the best of both approaches could not only help reconcile controversy but also lead to striking advances in medical science.

  7. The Puzzle of Coherence

    DEFF Research Database (Denmark)

    Andersen, Anne Bendix; Frederiksen, Kirsten; Beedholm, Kirsten

    2016-01-01

    Background During the past decade, politicians and healthcare providers have strived to create a coherent healthcare system across primary and secondary healthcare sectors in Denmark. Nevertheless, elderly patients with chronic diseases (EPCD) continue to report experiences of poor-quality care...... to an acute care ward to discharge and later in meetings with healthcare providers in general practice, outpatient clinics, home care and physiotherapy. Furthermore, field observations were conducted in general practice, home care and rehabilitation settings. Research design An explorative design based...... on an interactionistic approach was used. As a consequence, the focus of data collection is the production of meaning happening between human beings in social interaction in the field of cross-sectorial collaboration. Research questions The research questions reflect the interactionistic approach as they concentrate...

  8. Optical coherence in astrophysics

    CERN Document Server

    Moret-Bailly, Jacques

    2013-01-01

    Many physicists and most astrophysicists assume that the photon is a small particle which, in a very low pressure gas can only interact with a single molecule. Thus, the interaction of light with this gas is incoherent. W. E.Lamb Jr, W. P. Schleich, M. O. Scully and C. H. Townes (Reviews of Modern Physics 71, S263, 1999) have criticized this view: In accordance with quantum electrodynamics the photon is a pseudo-particle resulting from the quantization of a deterministic exchange of energy between identical molecules and a normal mode of electromagnetic field. Following Lamb et al., we study models in which some variables have an unusual value for a spectroscopist: extremely low pressure hydrogen, but huge light paths, extremely hot sources. However, the magnitudes of the spectral radiances and column densities can be similar in astrophysics and in a laboratory using lasers. Thus, several coherent effects must be taken into account: superradiance, multiphoton interactions, impulsive stimulated Raman scatterin...

  9. Coherent Scatter Imaging Measurements

    Science.gov (United States)

    Ur Rehman, Mahboob

    In conventional radiography, anatomical information of the patients can be obtained, distinguishing different tissue types, e.g. bone and soft tissue. However, it is difficult to obtain appreciable contrast between two different types of soft tissues. Instead, coherent x-ray scattering can be utilized to obtain images which can differentiate between normal and cancerous cells of breast. An x-ray system using a conventional source and simple slot apertures was tested. Materials with scatter signatures that mimic breast cancer were buried in layers of fat of increasing thickness and imaged. The result showed that the contrast and signal to noise ratio (SNR) remained high even with added fat layers and short scan times.

  10. Coherent imaging without phases

    CERN Document Server

    Moscoso, Miguel; Papanicolaou, George

    2015-01-01

    In this paper we consider narrow band, active array imaging of weak localized scatterers when only the intensities are recorded at an array with N transducers. We consider that the medium is homogeneous and, hence, wave propagation is fully coherent. This work is an extension of our previous paper, where we showed that using linear combinations of intensity-only measurements imaging of localized scatterers can be carried out efficiently using MUSIC or sparsity promoting optimization. Here we show the same strategy can be accomplished with only 3N-2 illuminations, therefore reducing enormously the data acquisition process. Furthermore, we show that in the paraxial regime one can form the images by using six illuminations only. In particular, this paraxial regime includes Fresnel and Fraunhofer diffraction. The key point of this work is that if one controls the illuminations, imaging with intensity-only can be easily reduced to a imaging with phases and, therefore, one can apply standard imaging techniques. Det...

  11. Quantum information and coherence

    CERN Document Server

    Öhberg, Patrik

    2014-01-01

    This book offers an introduction to ten key topics in quantum information science and quantum coherent phenomena, aimed at graduate-student level. The chapters cover some of the most recent developments in this dynamic research field where theoretical and experimental physics, combined with computer science, provide a fascinating arena for groundbreaking new concepts in information processing. The book addresses both the theoretical and experimental aspects of the subject, and clearly demonstrates how progress in experimental techniques has stimulated a great deal of theoretical effort and vice versa. Experiments are shifting from simply preparing and measuring quantum states to controlling and manipulating them, and the book outlines how the first real applications, notably quantum key distribution for secure communication, are starting to emerge. The chapters cover quantum retrodiction, ultracold quantum gases in optical lattices, optomechanics, quantum algorithms, quantum key distribution, quantum cont...

  12. Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Mogensen, Mette; Themstrup, Lotte; Banzhaf, Christina

    2014-01-01

    as the optical analogue to ultrasound. The inherent safety of the technology allows for in vivo use of OCT in patients. The main strength of OCT is the depth resolution. In dermatology, most OCT research has turned on non-melanoma skin cancer (NMSC) and non-invasive monitoring of morphological changes......Optical coherence tomography (OCT) has developed rapidly since its first realisation in medicine and is currently an emerging technology in the diagnosis of skin disease. OCT is an interferometric technique that detects reflected and backscattered light from tissue and is often described...... in a number of skin diseases based on pattern recognition, and studies have found good agreement between OCT images and histopathological architecture. OCT has shown high accuracy in distinguishing lesions from normal skin, which is of great importance in identifying tumour borders or residual neoplastic...

  13. Dental Extrusion with Orthodontic Miniscrew Anchorage: A Case Report Describing a Modified Method

    Directory of Open Access Journals (Sweden)

    Ricardo Fidos Horliana

    2015-01-01

    Full Text Available In recent years, the skeletal anchorage through miniscrews has expanded the treatment options in orthodontics (Yamaguchi et al., 2012. We hereby present a modified method for tooth extrusion for cases where crown-lengthening surgery is contraindicated for aesthetic reasons. This modified method uses three orthodontic appliances: a mini-implant, an orthodontic wire, and a bracket. The aim of this case report was to increase the length of the clinical crown of a fractured tooth (tooth 23 by means of an orthodontic extrusion with the modified method of Roth and Diedrich.

  14. Consensus Control Design for 360 MN Extrusion Machine Producing Process

    Directory of Open Access Journals (Sweden)

    Chao Wang

    2014-01-01

    Full Text Available This paper mainly addresses the issue of 360 MN extrusion machine and focuses on the stabilization control of main table attitude. We will first introduce the problem and then model the extrusion machine. As the machine is a multi-input multioutput (MIMO and strong coupling system, it is challenging to apply existing control theory to design a controller to stabilize the main table attitude. Motivated by recent research in the field of multiagent systems, we design a consensus control protocol for our system and derive our convergence conditions based directly on Routh stability criterion. The advantages of the design are also demonstrated by numerical simulation.

  15. PRELIMINARY INVESTIGATION OF PASTA EXTRUSION PROCESS: RHEOLOGICAL CHARACTERIZATION OF SEMOLINA DOUGH

    Directory of Open Access Journals (Sweden)

    Angelo Fabbri

    2007-06-01

    Full Text Available Rheological measurements were conducted on semolina doughs. Two doughs were considered, one directly taken from an extrusion plant and another mixed in lab conditions. A rotational viscometer was used in the plate-plate configuration. Creep tests were carried on too, to verify the possibility to neglect the elastic component of strain. It was investigated the influence of the temperature on the viscous behaviour of both doughs, while only on the lab mixed dough was tested the influence of moisture content. The aim of this research is the determination of a rheological model useful for a subsequent CFD analysis of the extrusion process.

  16. Evolution Of Precipitate Morphology During Extrusion In Mg ZK60A Alloy

    Directory of Open Access Journals (Sweden)

    Park J.

    2015-06-01

    Full Text Available In this study, a continuously casted ZK60A magnesium alloy (Mg-Zn-Zr was extruded in two different extrusion ratios, 6:1 and 10:1. The evolution of precipitates was investigated on the two extruded materials and compared with that of as-casted material. The microstructural analysis was performed by electron backscatter diffraction and transmission electron microscopy, and the compositional information was obtained using energy-dispersive X-ray spectroscopy. Several distinct morphologies of precipitates were observed, such as dot, rod, and disk shaped. The formation mechanisms of those precipitates were discussed with respect to the heat and strain during the extrusion process.

  17. Key technologies of "zero die trial" design system for aluminum profile extrusion

    Institute of Scientific and Technical Information of China (English)

    罗超; 李大永; 彭颖红; 左铁镛

    2004-01-01

    Aluminum alloy profile parts are widely used in the fields of aviation, equipment, automobile and ornamental industries. The construction method for "zero die trial" intelligent design system of aluminum extrusion die was studied based on KBE idea. An object-oriented knowledge language AEKL(Aluminum Extrusion Knowledge Language) was developed to construct intelligent knowledge model with three methods, frame, parameters and rules. On the aspect of knowledge reasoning, case-based reasoning was employed in addition to traditional rule-based reasoning method. API provided by CAD platform was used in geometry disposal. Finally, the corresponding prototyping system was established and an design example was shown.

  18. Debris extrusion by glide-path establishing endodontic instruments with different geometries

    Directory of Open Access Journals (Sweden)

    Jung-Hong Ha

    2016-06-01

    Conclusion: Creating the glide-path using nickel-titanium rotary files produced lower amounts of debris extrusion than using manual stainless-steel files. The progressive taper design of ProGlider, the center-off cross-section of One G, and the alternative-pitch design of ScoutRace may have increased the efficiencies of debris removal with minimal extrusion during glide-path preparation. Glide-path preparation using NiTi rotary files have better clinical efficiency than the manual stainless-steel file.

  19. Forming of tubes and bars of alumina/LY12 composites by liquid extrusion process

    Institute of Scientific and Technical Information of China (English)

    齐乐华; 李贺军; 崔培玲; 史忠科

    2003-01-01

    Tube and bar products of aluminum alloy composites reinforced by alumina short-fiber were formed in a single process with liquid extrusion technology. The microstructure verifies that the reinforcing effect is obvious in the deformation direction since fibers are distributed along this direction, which is resulted from the flow and crystallization under pressure of liquid metal and large plastic deformation of solidified metal in the process. The interface between fiber and matrix belongs to mechanical bonding. The fractograph demonstrates ductile mode. Liquid extrusion process opens up a new way for fabricating tube, bar and shaped products.

  20. THE IMPACT OF EXTRUSION ON THE BIOGAS AND BIOMETHANE YIELD OF PLANT SUBSTRATES

    Directory of Open Access Journals (Sweden)

    Krzysztof Pilarski

    2016-09-01

    Full Text Available The objective of the present work was to determine the effect of pretreatment by extrusion on the biogas and biomethane yield of lignocellulosic substrates such as maize silage and maize straw silage. The biogas yields of the substrates before and after treatment were compared. Moreover, energy efficiency of pretreatment by extrusion was analyzed in order to assess the applicability of the process in an agricultural biogas plant. Extrusion tests were carried out in a short single-screw extruder KZM-2 in which the length-to-diameter ratio of the screw was 6:1 and rotational speed was 200 rpm. The biogas yield tests of the plant substrates after extrusion were carried out in a laboratory scale, using 15 biofermenters operated in a periodic manner, at a constant temperature of 39°C (mesophilic digestion and controlled pH conditions. The gas-emission analysis was performed using a certified gas analyzer from Geotech GA5000. Pretreatment by extrusion was observed to improve the quantity of methane generated: in terms of fresh matter for maize silage subjected to extrusion, the methane yield was 16.48% higher than that of the non-extruded silage. On the other hand, maize straw silage after extrusion gave 35.30% more methane than did the same, non-extruded, material. Differences in yields relative to dry organic matter are also described in this paper. Taking into account the amount of energy that is spent on pretreatment and the generated amount of methane, the energy balance for the process gives an idea of the economics of the operation. For maize silage, energy efficiency was lower by 13.21% (-553.2 kWh/Mg, in contrast to maize straw silage, where the increase in energy was 33.49% (678.4 kWh/Mg. The obtained results indicate that more studies on the pretreatment and digestion of maize silage are required in order to improve the efficiency of its use for making biogas. To fully utilize its potential, it is necessary to know thoroughly the effect of

  1. Influence of Mg Content on Deformability of AlMg Alloys during Extrusion

    Directory of Open Access Journals (Sweden)

    Leśniak D.

    2016-03-01

    Full Text Available In this study the research on deformability of AlMg alloys with high Mg contents in extrusion was carried out. The different shapes from AlMg alloys containing 3.5%, 4.5% and 5.5% of Mg were extruded on 500 T semi-industrial press by using one-hole and multi-hole flat dies. The extrudates surface quality was under investigations in relation with the temperature-speed parameters of the extrusion process. The metal exit speed was estimated depending on the extrudates shape, wall thickness and Mg content. The alloy’s border solidus and liquidus temperatures were also determined.

  2. Die swell as an objective in the design of polymer extrusion dies

    Science.gov (United States)

    Siegbert, Roland; Behr, Marek; Elgeti, Stefanie

    2016-10-01

    This paper focuses on developing a suitable objective function for the inverse form of profile extrusion die design. First, the problem is motivated by introducing the extrusion die design process. After describing how Computer Aided Engineering enhances the traditional design process, a set of applicable objective functions is introduced. The main criteria for identifying the most suitable are computational applicability, robustness and smoothness of the functional. After discussing the results of several simulations, an objective function is proposed for the implementation in an existing optimization framework utilizing parameter-based optimization.

  3. Optical Coherence Tomography

    Science.gov (United States)

    Huang, David

    Optical coherence tomography (OCT) is a new method for noninvasive cross-sectional imaging in biological systems. In OCT, the longitudinal locations of tissue structures are determined by measuring the time-of-flight delays of light backscattered from these structures. The optical delays are measured by low coherence interferometry. Information on lateral position is provided by transverse scanning of the probe beam. The two dimensional map of optical scattering from internal tissue microstructures is then represented in a false-color or grayscale image. OCT is the optical analog of ultrasonic pulse-echo imaging, but with greatly improved spatial resolutions (a few microns). This thesis describes the development of this new high resolution tomographic imaging technology and the demonstration of its use in a variety of tissues under both in vitro and in vivo conditions. In vitro OCT ranging and imaging studies were performed using human ocular and arterial tissues, two clinically relevant examples of transparent and turbid media, respectively. In the anterior eye, precise measurements of cornea and anterior chamber dimensions were made. In the arterial specimens, the differentiation between fatty -calcified and fibromuscular tissues was demonstrated. In vivo OCT imaging in the retina and optic nerve head in human subjects was also performed. The delineation of retinal layers, which has not been possible with other noninvasive imaging techniques, is demonstrated in these OCT images. OCT has high spatial resolution but limited penetration into turbid tissue. It has potential for diagnostic applications where high resolution is needed and optical access is available, such as in the eye, skin, surgically exposed tissues, and surfaces that can be reached by various catheters and endoscopic probes. In particular, the measurement of fine retinal structures promises improvements in the diagnosis and management of glaucoma, macular edema and other vitreo-retinal diseases

  4. DEPOSITION OF TiBN HARD FILMS ON HOT-WORKING-STEEL DIES FOR ALUMINIUM EXTRUSION VIA A DUPLEX PROCESS

    Institute of Scientific and Technical Information of China (English)

    K. MUller

    2001-01-01

    Hot working steels have been used as die materials for hot extrusion of aluminium.Due to tribological interaction at elevated temperature between the die bearing and thesurface of extruded aluminium profiles, not only the surface quality of the extrudedproduct, but also the lifetime of the dies decreases. Deposition of TiBN hard films onthe die bearing could improve the die performance. Treatment should be done in aduplex process process combining a plasma nitriding pretreatment (PN) and a plasmaassisted chemical vapour deposition (PACVD) of TiBN. In this study the influence ofthe process conditions on the properties of the duplex coatings was investigated. Therelationship between structure and mechanical property was researched. For testingthese TiBN hardfilms under elevated temperature conditions and for comparison withother possible coatings special extrusion dies with different coated bearings were used.The extrusion trials were performed on the 8MN-extrusion press at the research anddevelopment center for extrusion, Technical University of Berlin.

  5. Coherence Properties of the LCLS

    Energy Technology Data Exchange (ETDEWEB)

    Ocko, Samuel

    2010-08-25

    The LINAC Coherent Light Source (LCLS), an X-Ray free-electron laser(FEL) based on the self amplified spontaneous emission principle, has recently come on-line. For many users it is desirable to have an idea of the level of transverse coherence of the X-Ray beam produced. In this paper, we analyze the output of GENESIS simulations of electrons traveling through the FEL. We first test the validity of an approach that ignores the details of how the beam was produced, and instead, by assuming a Gaussian-Schell model of transverse coherence, predicts the level of transverse coherence simply through looking at the beam radius at several longitudinal slices. We then develop a Markov chain Monte Carlo approach to calculating the degree of transverse coherence, which offers a {approx}100-fold speedup compared to the brute-force algorithm previously in use. We find the beam highly coherent. Using a similar Markov chain Monte Carlo approach, we estimate the reasonability of assuming the beam to have a Gaussian-Schell model of transverse coherence, with inconclusive results.

  6. Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: Evidence for diamond growth from slab melts

    Science.gov (United States)

    Thomson, A. R.; Kohn, S. C.; Bulanova, G. P.; Smith, C. B.; Araujo, D.; Walter, M. J.

    2016-11-01

    The trace element compositions of inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite, Brazil, are presented. Literature data for mineral/melt partition coefficients were collated, refitted and employed to interpret inclusion compositions. As part of this process an updated empirical model for predicting the partitioning behaviour of trivalent cations for garnet-melt equilibrium calibrated using data from 73 garnet-melt pairs is presented. High levels of trace element enrichment in inclusions interpreted as former calcium silicate perovskite and majoritic garnet preclude their origin as fragments of an ambient deep mantle assemblage. Inclusions believed to represent former bridgmanite minerals also display a modest degree of enrichment relative to mantle phases. The trace element compositions of 'NAL' and 'CF phase' minerals are also reported. Negative Eu, Ce, and Y/Ho anomalies alongside depletions of Sr, Hf and Zr in many inclusions are suggestive of formation from a low-degree carbonatitic melt of subducted oceanic crust. Observed enrichments in garnet and 'calcium perovskite' inclusions limit depths of melting to less than 600 km, prior to calcium perovskite saturation in subducting assemblages. Less enriched inclusions in sub-lithospheric diamonds from other global localities may represent deeper diamond formation. Modelled source rock compositions that are capable of producing melts in equilibrium with Juina-5 'calcium perovskite' and majorite inclusions are consistent with subducted MORB. Global majorite inclusion compositions suggest a common process is responsible for the formation of many superdeep diamonds, irrespective of geographic locality. Global transition zone inclusion compositions are reproduced by fractional crystallisation from a single parent melt, suggesting that they record the crystallisation sequence and melt evolution during this interaction of slab melts with ambient mantle. All observations are consistent with the

  7. International workshop on phase retrieval and coherent scattering. Coherence 2005

    Energy Technology Data Exchange (ETDEWEB)

    Nugent, K.A.; Fienup, J.R.; Van Dyck, D.; Van Aert, S.; Weitkamp, T.; Diaz, A.; Pfeiffer, F.; Cloetens, P.; Stampanoni, M.; Bunk, O.; David, C.; Bronnikov, A.V.; Shen, Q.; Xiao, X.; Gureyev, T.E.; Nesterets, Ya.I.; Paganin, D.M.; Wilkins, S.W.; Mokso, R.; Cloetens, P.; Ludwig, W.; Hignette, O.; Maire, E.; Faulkner, H.M.L.; Rodenburg, J.M.; Wu, X.; Liu, H.; Grubel, G.; Ludwig, K.F.; Livet, F.; Bley, F.; Simon, J.P.; Caudron, R.; Le Bolloc' h, D.; Moussaid, A.; Gutt, C.; Sprung, M.; Madsen, A.; Tolan, M.; Sinha, S.K.; Scheffold, F.; Schurtenberger, P.; Robert, A.; Madsen, A.; Falus, P.; Borthwick, M.A.; Mochrie, S.G.J.; Livet, F.; Sutton, M.D.; Ehrburger-Dolle, F.; Bley, F.; Geissler, E.; Sikharulidze, I.; Jeu, W.H. de; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Lurio, L.B.; Hu, X.; Jiao, X.; Jiang, Z.; Naryanan, S.; Sinha, S.K.; Lal, J.; Naryanan, S.; Sinha, S.K.; Lal, J.; Robinson, I.K.; Chapman, H.N.; Barty, A.; Beetz, T.; Cui, C.; Hajdu, J.; Hau-Riege, S.P.; He, H.; Stadler, L.M.; Sepiol, B.; Harder, R.; Robinson, I.K.; Zontone, F.; Vogl, G.; Howells, M.; London, R.; Marchesini, S.; Shapiro, D.; Spence, J.C.H.; Weierstall, U.; Eisebitt, S.; Shapiro, D.; Lima, E.; Elser, V.; Howells, M.R.; Huang, X.; Jacobsen, C.; Kirz, J.; Miao, H.; Neiman, A.; Sayre, D.; Thibault, P.; Vartanyants, I.A.; Robinson, I.K.; Onken, J.D.; Pfeifer, M.A.; Williams, G.J.; Pfeiffer, F.; Metzger, H.; Zhong, Z.; Bauer, G.; Nishino, Y.; Miao, J.; Kohmura, Y.; Yamamoto, M.; Takahashi, Y.; Koike, K.; Ebisuzaki, T.; Ishikawa, T.; Spence, J.C.H.; Doak, B

    2005-07-01

    The contributions of the participants have been organized into 3 topics: 1) phase retrieval methods, 2) X-ray photon correlation spectroscopy, and 3) coherent diffraction imaging. This document gathers the abstracts of the presentations and of the posters.

  8. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  9. Coherence in Linear Predicate Logic

    CERN Document Server

    Dosen, K

    2007-01-01

    Coherence with respect to Kelly-Mac Lane graphs is proved for categories that correspond to the multiplicative fragment without constant propositions of classical linear first-order predicate logic without or with mix. To obtain this result, coherence is first established for categories that correspond to the multiplicative conjunction-disjunction fragment with first-order quantifiers of classical linear logic, a fragment lacking negation. These results extend results published in previous two books by the authors, where coherence was established for categories of the corresponding fragments of propositional classical linear logic, which are related to proof nets, and which could be described as star-autonomous categories without unit objects.

  10. Coherent control of quantum dots

    DEFF Research Database (Denmark)

    Johansen, Jeppe; Lodahl, Peter; Hvam, Jørn Märcher

    In recent years much effort has been devoted to the use of semiconductor quantum dotsystems as building blocks for solid-state-based quantum logic devices. One importantparameter for such devices is the coherence time, which determines the number ofpossible quantum operations. From earlier...... measurements the coherence time of the selfassembledquantum dots (QDs) has been reported to be limited by the spontaneousemission rate at cryogenic temperatures1.In this project we propose to alter the coherence time of QDs by taking advantage of arecent technique on modifying spontaneous emission rates...

  11. Analysis of Crystallographic Textures in Aluminum Plates Processed by Equal Channel Angular Extrusion

    DEFF Research Database (Denmark)

    Li, Saiyi; Mishin, Oleg

    2014-01-01

    A modeling and experimental investigation has been conducted to explore the effect of processing route on texture evolution during equal channel angular extrusion (ECAE) of aluminum plate samples. It is found that although the textures in the plates develop along orientation fibers previously...

  12. Suppression of repeated adiabatic shear banding by dynamic large strain extrusion machining

    Science.gov (United States)

    Cai, S. L.; Dai, L. H.

    2014-12-01

    High speed machining (HSM) is an advanced production technology with great future potential. Chip serration or segmentation is a commonly observed phenomenon during high speed machining of metals, which is found to be ascribed to a repeated shear band formation fueled by thermo-plastic instability occurring within the primary shear zone. The occurrence of serrated chips leads to the cutting force fluctuation, decreased tool life, degradation of the surface finish and less accuracy in machine parts during high speed machining. Hence, understanding and controlling serrated chip formation in HSM are extremely important. In this work, a novel dynamic large strain extrusion machining (DLSEM) technique is developed for suppressing formation of serrated chips. The systematic DLSEM experiments of Ti-6Al-4V and Inconel 718 alloy with varying degrees of imposed extrusion constraint were carried out. It is found that there is a prominent chip morphology transition from serrated to continuous state and shear band spacing decreases with the constraint degree increasing. In order to uncover underlying mechanism of the imposed extrusion constraint suppressing repeated adiabatic shear banding in DLSEM, new theoretical models are developed where the effects of extrusion constraint, material convection due to chip flow and momentum diffusion during shear band propagation are included. The analytical expressions for the onset criterion of adiabatic shear band and shear band spacing in DLSEM are obtained. The theoretical predictions are in agreement with the experimental results.

  13. Analysis of Key Technologies and Equipments Development of Largescale Melted Extrusion Manufacturing Systems

    Institute of Scientific and Technical Information of China (English)

    Lei ZHANG; Sheng CHEN; Yongnian YAN; Renji ZHANG

    2003-01-01

    To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (MEM)process has been developed success

  14. 76 FR 30650 - Aluminum Extrusions from the People's Republic of China: Antidumping Duty Order

    Science.gov (United States)

    2011-05-26

    ... products produced by a method of casting. Cast aluminum products are properly identified by four digits... following Aluminum Association designations are representative of aluminum alloys for casting: 208.0, 295.0... International Trade Administration Aluminum Extrusions from the People's Republic of China: Antidumping Duty...

  15. 76 FR 30653 - Aluminum Extrusions From the People's Republic of China: Countervailing Duty Order

    Science.gov (United States)

    2011-05-26

    ... products produced by a method of casting. Cast aluminum products are properly identified by four digits... following Aluminum Association designations are representative of aluminum alloys for casting: 208.0, 295.0... International Trade Administration Aluminum Extrusions From the People's Republic of China: Countervailing Duty...

  16. [An esthetic crown lengthening technic of the clinical crown. Rapid orthodontic extrusion].

    Science.gov (United States)

    Blase, D; Bercy, P

    1993-01-01

    Rapid orthodontic root extrusion is an esthetic technique for clinical crown lengthening. Associated with periodontal surgery, it exposes subgingival lesions and preserves an harmonious gingivo-osseous morphology. This conservative technique is easy to apply by the general dentist as it requires non specialised material.

  17. Jute fiber reinforced polypropylene produced by continuous extrusion compounding. Part 1. Processing and ageing properties

    NARCIS (Netherlands)

    Oever, van den M.J.A.; Snijder, M.H.B.

    2008-01-01

    This article addresses the processing and ageing properties of jute fiber reinforced polypropylene (PP) composites. The composite has been manufactured by a continuous extrusion process and results in free flowing composite granules, comprising up to 50 weight percent (wt %) jute fiber in PP. These

  18. An effective split of flow and die deformation calculations of aluminium extrusion

    NARCIS (Netherlands)

    Mooi, H.G.; Koenis, P.T.G.; Huétink, J.

    1999-01-01

    The purpose of the research project of which this paper is a result is to gain insight in design and control parameters of aluminium extrusion by FE simulations. This is done by means of a thermal FE code based on an ALE algorithm (Dieka). A short overview is given of the material models as well as

  19. An effective split of flow and deformation calculations of aluminium extrusion

    NARCIS (Netherlands)

    Mooi, H.G.; Mooi, H.G.; Koenis, P.T.G.; Huetink, Han

    1999-01-01

    The purpose of the research project of which this paper is a result is to gain insight in design and control parameters of aluminium extrusion by FE simulations. This is done by means of a thermal FE code based on an ALE algorithm (Dieka). A short overview is given of the material models as well as

  20. Evaluation of sorghum flour as extender in plywood adhesives for sprayline coaters or foam extrusion

    Science.gov (United States)

    This study was conducted to evaluate sorghum flour as protein extender in plywood adhesive for sprayline coaters or foam extrusion. Defatted sorghum flour, containing 0.2% (dry basis, db) residual oil and 12.0% (db) crude protein, was analyzed for solubility and foaming properties. Sorghum flour pr...

  1. Jute fiber reinforced polypropylene produced by continuous extrusion compounding. Part 1. Processing and ageing properties

    NARCIS (Netherlands)

    Oever, van den M.J.A.; Snijder, M.H.B.

    2008-01-01

    This article addresses the processing and ageing properties of jute fiber reinforced polypropylene (PP) composites. The composite has been manufactured by a continuous extrusion process and results in free flowing composite granules, comprising up to 50 weight percent (wt %) jute fiber in PP. These

  2. An effective split of flow and die deformation calculations of aluminium extrusion

    NARCIS (Netherlands)

    Mooi, H.G.; Koenis, P.T.G.; Huétink, J.

    1999-01-01

    The purpose of the research project of which this paper is a result is to gain insight in design and control parameters of aluminium extrusion by FE simulations. This is done by means of a thermal FE code based on an ALE algorithm (Dieka). A short overview is given of the material models as well as

  3. Deformation and microstructure characterization during semi-solid extrusion of Al-4Cu-Mg alloy

    Institute of Scientific and Technical Information of China (English)

    LU Ya-lin; LI Miao-quan; LI Xing-cheng

    2006-01-01

    Effects of the process parameters, including deformation temperature, punch velocity and extrusion ratio, on the deformation and microstructure characterization during the semi-solid extrusion of Al-4Cu-Mg alloy, were investigated. The experimental results show that the load decreases with an increase of deformation temperature and/or a decrease of punch velocity.When the displacement is more than 4 mm, the load decreases significantly with an increase of the deformation temperature, which is related to the high liquid fraction. The microstructure varies with the process parameters and deformation regions. It can be found that the dynamic recovery occurs during the semi-solid extrusion of Al-4Cu-Mg alloy at lower deformation temperature.Subsequently, the microstructure elongated gradually polygonizes with an increase of deformation temperature. So, the higher deformation temperature should be chosen during the semi-solid extrusion of Al-4Cu-Mg alloy because the grains polygonized and high liquid fractions are beneficial to deformation.

  4. Effect of extrusion, espansion and toasting on the nutritional value of peas, faba beans and lupins

    Directory of Open Access Journals (Sweden)

    Filippo Rossi

    2010-01-01

    Full Text Available An assessment was made of the effect that different treatments (toasting, expansion, extrusion have on the nutritionalvalue of protein plants (pea, faba bean, lupin. In a randomized block design, feeds were screened for enzymaticdigestibility of starch and protein, N solubility and in vitro protein degradability. Expansion and extrusion cause increasedstarch enzymatic degradability while toasting produced virtually no effects. In peas this value increased from 11.80% inmeal to 39.70% in the extruded product; 85.37% is the percentage for the expanded product, while 10.90% is the starchdigestibility value for toasted peas. In faba beans the extrusion process increased starch digestibility from 11.39% to85.05%, while in extruded lupins a complete starch hydrolysis was obtained, while in the meal the polysaccharide digestionwas 54.48%.The expansion and extrusion processes significantly decreased rumen degradability during the first 8 hours of incubation.Toasted peas had lower degradability if compared with controls but not with the other treatments. The onlypotentially alternative source to soybean is the extruded faba bean. In spite of its lower protein content, this feed ischaracterized by a considerably lower in vitro protein degradability than soybean. This implies that the digestible foodprotein content is comparable (124.90 g/kg DM to that of soybean (109.78 g/kg DM and definitely higher than thatof all other protein plants.

  5. Enhancing Tensile Response of Sn Using Cu at Nano Length Scale and High Temperature Extrusion

    Science.gov (United States)

    2009-02-01

    extrusion. Density Measurement Density measurements were performed in accordance with Archimedes ’ principle on four randomly selected polished...of Engineering Materials, second ed., McGraw-Hill, New York (1999). [6] R. M. German, Sintering Theory and Practice, John Wiley and Sons Inc., New

  6. Definition of a JA2 equivalent propellant to be produced by continuous solvent-less extrusion

    NARCIS (Netherlands)

    Manning, T.G.; Leone, J.; Zebregs, M.; Ramlal, D.R.; Driel, C.A. van

    2013-01-01

    The aim of this work is to demonstrate the manufacturing of a propellant by solvent-less continuous twin screw extrusion processing while maintaining gun performance characteristics of conventional JA-2 propellant. This is elucidated by explicitly researching the relationship between interior ballis

  7. Effect of Different Extrusion Parameters on Dietary Fiber in Wheat Bran and Rye Bran.

    Science.gov (United States)

    Andersson, Annica A M; Andersson, R; Jonsäll, Anette; Andersson, Jörgen; Fredriksson, Helena

    2017-06-01

    Wheat bran and rye bran are mostly used as animal feed today, but their high content of dietary fiber and bioactive components are beneficial to human health. Increased use of bran as food raw material could therefore be desirable. However, bran mainly contains unextractable dietary fiber and deteriorates the sensory properties of products. Processing by extrusion could increase the extractability of dietary fiber and increase the sensory qualities of bran products. Wheat bran and rye bran were therefore extruded at different levels of moisture content, screw speed and temperature, in order to find the optimal setting for increased extractability of dietary fiber and positive sensory properties. A water content of 24% for wheat bran and 30% for rye bran, a screw speed of 400 rpm, and a temperature of 130 °C resulted in the highest extractability of total dietary fiber and arabinoxylan. Arabinoxylan extractability increased from 5.8% in wheat bran to 9.0% in extruded wheat bran at those settings, and from 14.6% to 19.2% for rye bran. Total contents of dietary fiber and arabinoxylan were not affected by extrusion. Content of β-glucan was also maintained during extrusion, while its molecular weight decreased slightly and extractability increased slightly. Extrusion at these settings is therefore a suitable process for increasing the use of wheat bran and rye bran as a food raw material. © 2017 Institute of Food Technologists®.

  8. Missing LINQ: extrusion of a new-generation implantable loop recorder in a child.

    Science.gov (United States)

    Chaouki, Ahmad S; Czosek, Richard J; Spar, David S

    2016-10-01

    Cardiac rhythm monitoring has been facilitated by the use of implantable loop recorders. New models of these devices are 87% smaller than before allowing for easier implantation and use in the paediatric population. Recommendations are for closure with adhesive. We report a device extrusion in a 6-year-old patient. Based on this, our practice has changed to include subcutaneous sutures this complication.

  9. effectof extrusion conditions on aflatoxin content of corn–peanut flakes

    African Journals Online (AJOL)

    Aynadis

    ... operating conditions on the reduction of total and individual aflatoxins ... cereals, flakes, breading crumbs and animal feeds. .... rotating twin screw food extruder (model. Clextral, BC-21 .... accepted at 0.05 level of probability. (p<0.05). .... The collective action of the ... monostea rate on the extrusion behavior of maize grits ...

  10. Raw material changes and their processing parameters in an extrusion cooking process

    DEFF Research Database (Denmark)

    Cheng, Hongyuan; Friis, Alan

    In this work, the effects of raw material and process parameters on product expansion in a fish feed extrusion process were investigated. Four different recipes were studied with a pilot-scale twin-screw co-rotating extruder according to a set of pre-defined processing conditions. In the four...

  11. Effects of extrusion cooking on physicochemical properties of white and red ginseng (powder)

    Science.gov (United States)

    Gui, Ying; Ryu, Gi-Hyung

    2013-01-01

    A systematic comparison of the physicochemical properties of white ginseng (WG), extruded white ginseng (EWG), red ginseng (RG), and extruded red ginseng (ERG) was performed. The aim of the present study was to identify the effects of the physicochemical properties of ginseng by extrusion cooking. The highest value of the water absorption index (WAI) was 3.64 g/g obtained from EWG, and the highest value of the water solubility index (WSI) was 45.27% obtained from ERG. The ERG had a better dispersibility compared with other samples. Extrusion cooking led to a significant increase in acidic polysaccharide and total sugar content but resulted in a decrease in crude fat and reducing sugar contents. Enzyme treatment led to a sharp increase in acidic polysaccharide content, especially the cellulose enzyme. Extrusion cooking led to a significant increase in 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power, and the increases in WG and RG were 13.56% (0.038) and 3.56% (0.026), respectively. The data of this study provide valuable information about the effects of extrusion on quality changes of EWG and ERG. PMID:24748839

  12. Control of material flow in a combined backward can - forward rod extrusion

    DEFF Research Database (Denmark)

    Kuzman, K; Pfeifer, E; Bay, Niels

    1996-01-01

    The paper deals with an analysis of an extrusion process with a divided material flow. As we are forced to seek for optimal technological solutions with short testing times and low risks and costs, a reliable process evaluation is of the greatest importance. The paper discusses the influences of ...

  13. Study on Hot Deformation Behavior of 7085 Aluminum Alloy during Backward Extrusion Process

    Directory of Open Access Journals (Sweden)

    R. B. Mei

    2015-01-01

    Full Text Available Compression test was carried out and the true stress-strain curves were obtained from the hot compression of 7085 alloy. A numerical simulation on the deformation behavior of 7085 aluminum alloy during the backward extrusion was also performed by finite element method. The results show that dynamic recrystallization occurs in the hot compression of 7085 alloy and the peak stress reaches higher values as the strain rate increases and deformation temperature decreases. The backward extrusion processes include contact deformation, initial deformation, and steady deformation. Severe plastic deformation of shear and compression occurs when the metal flowed into the channel between fillet of punch and wall of die so that the grain size can be refined by backward extrusion. The deformation in the region of top of wall is too small to meet the mechanical properties of requirements and the metal usually needs to be trimmed. The experiments with the same parameters as simulation had been carried out and the experimental cup after extrusion has better quality.

  14. Study of Microstructure and Mechanical Properties Effects on Workpiece Quality in Sheet Metal Extrusion Process

    Directory of Open Access Journals (Sweden)

    Chatkaew Suriyapha

    2015-01-01

    Full Text Available Sheet metal extrusion is a metal forming process in which the movement of a punch penetrates a sheet metal surface and it flows through a die orifice; the extruded parts can be deflected to have an extrusion cavity and protrusion on the opposite side. Therefore, this process results in a narrow region of highly localized plastic deformation due to the formation and microstructure effect on the work piece. This research investigated the characteristics of the material-flow behavior during the formation and its effect on the microstructure of the extruded sheet metal using the finite element method (FEM. The actual parts and FEM simulation model were developed using a blank material made from AISI-1045 steel with a thickness of 5 mm; the material’s behavior was determined subject to the punch penetration depths of 20%, 40%, 60%, and 80% of the sheet thickness. The results indicated the formation and microstructure effects on the sheet metal extrusion parts and defects. Namely, when increasing penetration, narrowing the die orifice the material flows through, the material was formed by extruding, and defects were visibility, and the microstructure of the material’s grains’ size was flat and very fine. Extrusion defects were not found in the control material flow. The region of highly localized plastic deformation affected the material gain and mechanical properties. The FEM simulation results agreed with the experimental results. Moreover, FEM could be investigated as a tool to decrease the cost and time in trial and error procedures.

  15. Twin screw extrusion processing of feed blends containing distillers dried grains with solubles

    Science.gov (United States)

    Extrusion trials were conducted with varying levels of distillers dried grains with solubles (DDGS) along with soy flour, corn flour, fish meal, vitamin mix, mineral mix and net protein content adjusted to 28% using a Wenger TX-52 twin screw extruder. The properties of extrudates obtained with exper...

  16. Efficient continuous synthesis of high purity deep eutectic solvents by twin screw extrusion.

    Science.gov (United States)

    Crawford, D E; Wright, L A; James, S L; Abbott, A P

    2016-03-18

    Mechanochemical synthesis has been applied to the rapid synthesis of Deep Eutectic Solvents (DESs), including Reline 200 (choline chloride : urea, 1 : 2), in a continuous flow methodology by Twin Screw Extrusion (TSE). This gave products in higher purity and with Space Time Yields (STYs), four orders of magnitude greater than for batch methods.

  17. Effect of needle insertion depth and root canal curvature on irrigant extrusion ex vivo

    NARCIS (Netherlands)

    Psimma, Z.; Boutsioukis, C.; Kastrinakis, E.; Vasiliadis, L.

    2013-01-01

    Introduction The aim of this study was to evaluate the effect of needle type and insertion depth, apical preparation size, and root canal curvature on irrigant extrusion by using a recently introduced method. Methods Sixteen human teeth with a straight root canal (group A) and 16 with a moderatel

  18. Efficient encapsulation of plasmid DNA in anionic liposomes by a freeze/thaw extrusion procedure

    NARCIS (Netherlands)

    Schoen, P; Bijl, L; Wilschut, J

    1998-01-01

    In this study we investigated whether intact plasmid DNA can be efficiently encapsulated in anionic liposomes prepared by freeze/thaw and extrusion techniques. There is controversy about this method of DNA encapsulation, especially as to whether DNA remains intact and retains its biological activity

  19. Polycarbonate modified with crystallisable bis-ester tetra-amide units in a reaction extrusion process

    NARCIS (Netherlands)

    Zuiderduin, W.C.J.; Gaymans, R.J.

    2008-01-01

    Dry blends of polycarbonate (PC) and a bis-ester tetra-amide were extruded at 305 °C with a mini twin screw extruder. The bis-ester tetra-amide diamide (T6T6T-dimethyl) was composed of two and a half repeat units of Nylon 6,T and had methyl ester endgroups. During the extrusion, a

  20. Condensed tannins in traditional wet-cooked and modern extrusion-cooked sorghum porridges

    CSIR Research Space (South Africa)

    Dlamini, NR

    2009-07-01

    Full Text Available the quantity and profile of condensed tannins in traditional wet-cooked and modern ready-to-eat extrusion-cooked sorghum porridges. CT were analyzed using normal-phase HPLC with fluorescence detection and their content was compared to CT and total phenols...

  1. Development of extrusion equipment and technology for the production of cereals

    Directory of Open Access Journals (Sweden)

    O. V. Abramov

    2012-01-01

    Full Text Available As a result, an integrated approach has been optimized structure designed muesli bars, represented by the modernized technology of their production, developed a mathematical model of motion of the molten product in the form of channels and extrusion of the matrix on the basis of the data presented molding construction site.

  2. The Core Extrusion Schema-Revised: Hiding Oneself Predicts Severity of Social Interaction Anxiety.

    Science.gov (United States)

    Levinson, Cheri A; Rodebaugh, Thomas L; Lim, Michelle H; Fernandez, Katya C

    2017-01-01

    Cognitive behavioral models of social anxiety disorder (SAD) suggest that fear of negative evaluation is a core fear or vulnerability for SAD. However, why negative evaluation is feared is not fully understood. It is possible that core beliefs contribute to the relationship between fear of negative evaluation and SAD. One of these beliefs may be a core extrusion schema: a constellation of beliefs that one's true self will be rejected by others and therefore one should hide one's true self. In the current study (N = 699), we extended research on the Core Extrusion Schema and created a shortened and revised version of the measure called the Core Extrusion Schema-Revised The Core Extrusion Schema-Revised demonstrated good factor fit for its two subscales (Hidden Self and Rejection of the True Self) and was invariant across gender and ethnicity. The Hidden Self subscale demonstrated excellent incremental validity within the full sample as well as in participants diagnosed with generalized SAD. Specifically, the Hidden Self subscale may help explain severity of social interaction anxiety. This measure could be used with individuals diagnosed with generalized SAD to design exposures targeting these core beliefs.

  3. High strength Al–Al2O3p composites: Optimization of extrusion parameters

    DEFF Research Database (Denmark)

    Luan, B.F.; Hansen, Niels; Godfrey, A.;

    2011-01-01

    on an investigation of their mechanical properties and microstructure, as well as on the surface quality of the extruded samples. The evaluation shows that material with good strength, though with limited ductility, can be reliably obtained using a production route of squeeze casting, followed by hot extrusion...

  4. High Speed D.C. Casting of AA-6063 Extrusion Ingot

    Science.gov (United States)

    Nawata, S.; Kubota, M.; Yokota, K.

    The purpose of this project is to develop the technique of high speed D.C. casting of aluminium extrusion billets. The project is aimed at improving the productivity of billet casting with respect to the large demand for extruded materials and anticipated increase in labour expenses.

  5. Polymeric formulations for drug release prepared by hot melt extrusion : application and characterization

    NARCIS (Netherlands)

    Stanković, Milica; Frijlink, Henderik W; Hinrichs, Wouter L J

    2015-01-01

    Over the past few decades hot melt extrusion (HME) has emerged as a powerful processing technology for the production of pharmaceutical solid dosage forms in which an active pharmaceutical ingredient (API) is dispersed into polymer matrices. It has been shown that formulations using HME can provide

  6. Superhydrophobic Properties of Nanotextured Polypropylene Foils Fabricated by Roll-to-Roll Extrusion Coating

    DEFF Research Database (Denmark)

    Telecka, Agnieszka; Murthy, Swathi; Sun, Ling

    2016-01-01

    We demonstrate the use of roll-to-roll extrusion coating (R2R-EC) for fabrication of nanopatterned polypropylene (PP) foils with strong antiwetting properties. The antiwetting nanopattern is originated from textured surfaces fabricated on silicon wafers by a single-step method of reactive ion...

  7. Effect of fermentation and extrusion on the release of selected minerals from lupine grain preparations

    Directory of Open Access Journals (Sweden)

    Rafał W. Wójciak

    2009-09-01

    Full Text Available Introduction. Antinutritional factors in legumes lower the nutritional value of foods by lowering the digestibility or bioavailability of nutrients. Technological processes applied in food production (e.g. extrusion, fermentation, germination may influence the leguminous seeds matrix composition which in consequence may affect (improve or decrease mineral bioaccessibility and uptake in animals and humans. The aim of this study was to determine the effect of fermentation and extrusion processing, as well as their combination, on the potential availability of Fe, Cu, and Zn from lupine grain preparations. Materials and methods. The content and the release of Fe, Cu and Zn from three different lupine species (Lupinus albus, Lupinus luteus, Lupinus angustifolius was determined. The samples were subjected to enzymatic digestion under in vitro conditions. The content of minerals in lupine grains before and after enzymatic digestion was determined by the flame atomic absorption spectrometry. Results. The degree of release of Fe, Cu, and Zn from dehulled lupine grains was higher than from whole grains. Fermentation processing increased the degree of Fe release, extrusion decreased the degree of Cu release, while the extrusion after fermentation processing increased the degree of Fe release from lupine grain preparations. Conclusions. The degree of mineral release from lupine grains depends on the hull content, technological processing applied and the lupine variety.

  8. 钢丝缠绕黑色金属挤压筒的设计%Design of Steel Wire Wound Extrusion Containers for Steel Hot Extrusion Process

    Institute of Scientific and Technical Information of China (English)

    刘长勇; 张磊; 林峰; 张人佶; 颜永年; 康飞宇

    2013-01-01

    挤压筒是大口径厚壁无缝钢管热挤压工艺中最为重要的模具,传统的多层组合挤压筒设计方法面临很大挑战.提出采用钢丝缠绕预紧挤压筒的方案,由于钢丝在高温下存在蠕变加速和应力松弛,将钢丝缠绕技术应用于挤压筒的最大问题是解决挤压筒预热与钢丝防护之间的矛盾.针对此矛盾,分析钢丝缠绕挤压筒设计中的关键问题包括预热、钢丝防护和预应力分布控制,提出高温钢锭内置预热和电加热预热两种设计方案,分别分析两种设计方案存在的问题、解决方法和优缺点.针对电加热预热挤压筒,提出新型的热致预应力方法来产生预紧力,将内衬和中衬预热至350℃以上,中衬和外衬之间设有隔热层,经隔热后外衬和钢丝层温度低于80℃,利用两者之间温度差而导致的热膨胀量差值来产生预紧力.基于此想法,设计制造内直径170 mm的挤压筒原理样件,通过温度测试和应力测试,表明所提出的电加热预热挤压筒可达到预期的预紧效果,为挤压筒的设计探讨一种新型的设计方法.%Extrusion container is the most important tooling in large steel tube extrusion process. Traditional design approaches such as multi-layered extrusion container would meet great challenges for large extrusion container. Steel wire wound extrusion is proposed. Due to accelerated creep behavior and stress relaxation of steel wire under high temperature, the primary difficulty of applying steel wire winding to the design of extrusion container is to solve the conflict between preheating and protection of the wire from high temperature. The key problems of wire wound containers including preheating, steel wire protection and control of prestress distribution are analyzed. Two solutions to preheating are proposed including hot billet preheating and electrical heating rods. The problems, solutions, advantages and disadvantages are discussed respectively. A

  9. On the potential for lunar highlands Mg-suite extrusive volcanism and implications concerning crustal evolution

    Science.gov (United States)

    Prissel, Tabb C.; Whitten, Jennifer L.; Parman, Stephen W.; Head, James W.

    2016-10-01

    The lunar magnesian-suite (Mg-suite) was produced during the earliest periods of magmatic activity on the Moon. Based on the cumulate textures of the samples and a lack of evidence for Mg-suite extrusives in both the sample and remote sensing databases, several petrogenetic models deduce a predominantly intrusive magmatic history for Mg-suite lithologies. Considering that ∼18% of the lunar surface is covered by mare basalt flows, which are substantially higher in density than estimated Mg-suite magmas (∼2900 versus ∼2700 kg/m3), the apparent absence of low-density Mg-suite volcanics is surprising. Were Mg-suite magmas predominantly intrusive, or have their extrusive equivalents been covered by subsequent impact ejecta and/or later stage volcanism? If Mg-suite magmas were predominantly intrusive, what prevented these melts from erupting? Or, if they are present as extrusives, what regions of the Moon are most likely to contain Mg-suite volcanic deposits? This study investigates buoyancy-driven ascent of Mg-suite parental melts and is motivated by recent measurements of crustal density from GRAIL. Mg-suite dunite, troctolite, and spinel anorthosite parental melts (2742, 2699, and 2648 kg/m3, respectively) are considered, all of which have much lower melt densities relative to mare basalts and picritic glasses. Mg-suite parental melts are more dense than most of the crust and would not be expected to buoyantly erupt. However, about 10% of the lunar crust is greater in density than Mg-suite melts. These areas are primarily within the nearside southern highlands and South Pole-Aitken (SP-A) basin. Mg-suite extrusions and/or shallow intrusions were possible within these regions, assuming crustal density structure at >4.1 Ga was similar to the present day crust. We review evidence for Mg-suite activity within both the southern highlands and SP-A and discuss the implications concerning crustal evolution as well as Mg-suite petrogenesis. Lower crustal densities

  10. AZ系列镁合金热模拟挤压过程中挤压力的研究%Extrusion Force of AZ Series Mg Alloy During Thermal Simulated Extrusion Forming

    Institute of Scientific and Technical Information of China (English)

    彭建; 周绸; 李权

    2011-01-01

    AZ 10, AZ31, AZ61 and AZ91 magnesium alloys were deformed with simulated extrusion system on Gleeble 1500D, which can determine the extrusion force during extrusion forming process. The microstructure of the alloys and the evolution of extrusion force were investigated. The results show that the extrusion force increases gradually with the increase of alloy element. Aimed at the same magnesium alloy, the deformed alloy with previous homogenization before extrusion has more extrusion force than that without homogenization, and dynamic recrystallization is a decisive factor in extrusion force during extrusion forming.%通过在Gleeble1500D热模拟试验机上对AZ10、AZ31、AZ61和AZ91镁合金进行模拟挤压,并对热模拟挤压成形过程中的挤压力进行测定,研究AZ系列镁合金热模拟挤压成形过程挤压力及其组织变化.研究结果表明,在AZ系列镁合金中,随着合金元素含量的增多,挤压力逐渐增大,并且同种镁合金在挤压前经均匀化退火处理后所需的挤压力比未经均匀化处理的合金所需挤压力大,动态再结晶是影响其挤压力大小的决定性因素.

  11. Pairing versus quarteting coherence length

    CERN Document Server

    Delion, Doru S

    2015-01-01

    We systematically analyse the coherence length in even-even nuclei. The pairing coherence length in the spin-singlet channel for the effective density dependent delta (DDD) and Gaussian interaction is estimated. We consider in our calculations bound states as well as narrow resonances. It turns out that the pairing gaps given by the DDD interaction are similar to those of the Gaussian potential if one renormalizes the radial width to the nuclear radius. The correlations induced by the pairing interaction have in all considered cases a long range character inside the nucleus and decrease towards the surface. The mean coherence length is larger than the geometrical radius for light nuclei and approaches this value for heavy nuclei. The effect of the temperature and states in continuum is investigated. Strong shell effects are evidenced, especially for protons. We generalize this concept to quartets by considering similar relations, but between proton and neutron pairs. The quartet coherence length has a similar...

  12. Coherent Radio Emission from Pulsars

    CERN Document Server

    Mitra, Dipanjan; Gil, Janusz

    2015-01-01

    We review a physical model where the high brightness temperature of 10$^{25}-10^{30}$ K observed in pulsar radio emission is explained by coherent curvature radiation excited in the relativistic electron-positron plasma in the pulsar magnetosphere.

  13. Coherent exciton-polariton devices

    Science.gov (United States)

    Fraser, Michael D.

    2017-09-01

    The Bose-Einstein condensate of exciton-polaritons has emerged as a unique, coherent system for the study of non-equilibrium, macroscopically coherent Bose gases, while the full confinement of this coherent state to a semiconductor chip has also generated considerable interest in developing novel applications employing the polariton condensate, possibly even at room temperature. Such devices include low-threshold lasers, precision inertial sensors, and circuits based on superfluidity with ultra-fast non-linear elements. While the demonstration and development of such devices are at an early stage, rapid progress is being made. In this review, an overview of the exciton-polariton condensate system and the established and emerging material systems and fabrication techniques are presented, followed by a critical, in-depth assessment of the ability of the coherent polariton system to deliver on its promise of devices offering either new functionality and/or room-temperature operation.

  14. Coherent Control of Bond Making

    CERN Document Server

    Levin, Liat; Rybak, Leonid; Kosloff, Ronnie; Koch, Christiane P; Amitay, Zohar

    2014-01-01

    We demonstrate for the first time coherent control of bond making, a milestone on the way to coherent control of photo-induced bimolecular chemical reactions. In strong-field multiphoton femtosecond photoassociation experiments, we find the yield of detected magnesium dimer molecules to be enhanced for positively chirped pulses and suppressed for negatively chirped pulses. Our ab initio model shows that control is achieved by purification via Franck-Condon filtering combined with chirp-dependent Raman transitions. Experimental closed-loop phase optimization using a learning algorithm yields an improved pulse that utilizes vibrational coherent dynamics in addition to chirp-dependent Raman transitions. Our results show that coherent control of binary photo-reactions is feasible even under thermal conditions.

  15. Quantitative measures of meniscus extrusion predict incident radiographic knee osteoarthritis – data from the Osteoarthritis Initiative

    Science.gov (United States)

    Emmanuel, K.; Quinn, E.; Niu, J.; Guermazi, A.; Roemer, F.; Wirth, W.; Eckstein, F.; Felson, D.

    2017-01-01

    SUMMARY Objective To test the hypothesis that quantitative measures of meniscus extrusion predict incident radiographic knee osteoarthritis (KOA), prior to the advent of radiographic disease. Methods 206 knees with incident radiographic KOA (Kellgren Lawrence Grade (KLG) 0 or 1 at baseline, developing KLG 2 or greater with a definite osteophyte and joint space narrowing (JSN) grade ≥1 by year 4) were matched to 232 control knees not developing incident KOA. Manual segmentation of the central five slices of the medial and lateral meniscus was performed on coronal 3T DESS MRI and quantitative meniscus position was determined. Cases and controls were compared using conditional logistic regression adjusting for age, sex, BMI, race and clinical site. Sensitivity analyses of early (year [Y] 1/2) and late (Y3/4) incidence was performed. Results Mean medial extrusion distance was significantly greater for incident compared to non-incident knees (1.56 mean ± 1.12 mm SD vs 1.29 ± 0.99 mm; +21%, P < 0.01), so was the percent extrusion area of the medial meniscus (25.8 ± 15.8% vs 22.0 ± 13.5%; +17%, P < 0.05). This finding was consistent for knees restricted to medial incidence. No significant differences were observed for the lateral meniscus in incident medial KOA, or for the tibial plateau coverage between incident and non-incident knees. Restricting the analysis to medial incident KOA at Y1/2 differences were attenuated, but reached significance for extrusion distance, whereas no significant differences were observed at incident KOA in Y3/4. Conclusion Greater medial meniscus extrusion predicts incident radiographic KOA. Early onset KOA showed greater differences for meniscus position between incident and non-incident knees than late onset KOA. PMID:26318658

  16. Using artificial neural networks to model extrusion processes for the manufacturing of polymeric micro-tubes

    Science.gov (United States)

    Mekras, N.; Artemakis, I.

    2012-09-01

    In this paper a methodology and an application example are presented aiming to show how Artificial Neural Networks (ANNs) can be used to model manufacturing processes when mathematical models are missing or are not applicable e.g. due to the micro- & nano-scaling, due to non-conventional processes, etc. Besides the ANNs methodology, the results of a Software System developed will be presented, which was used to create ANNs models for micro & nano manufacturing processes. More specifically results of a specific application example will be presented, concerning the modeling of extrusion processes for polymeric micro-tubes. ANNs models are capable for modeling manufacturing processes as far as adequate experimental and/or historical data of processes' inputs & outputs are available for their training. The POLYTUBES ANNs models have been trained and tested with experimental data records of process' inputs and outputs concerning a micro-extrusion process of polymeric micro-tubes for several materials such as: COC, PC, PET, PETG, PP and PVDF. The main ANN model of the extrusion application example has 3 inputs and 9 outputs. The inputs are: tube's inner & outer diameters, and the material density. The model outputs are 9 process parameters, which correspond to the specific inputs e.g. process temperature, die inner & outer diameters, extrusion pressure, draw speed etc. The training of the ANN model was completed, when the errors for the model's outputs, which expressed the difference between the training target values and the ANNs outputs, were minimized to acceptable levels. After the training, the micro-extrusion ANN is capable to simulate the process and can be used to calculate model's outputs, which are the process parameters for any new set of inputs. By this way a satisfactory functional approximation of the whole process is achieved. This research work has been supported by the EU FP7 NMP project POLYTUBES.

  17. Co-extrusion as manufacturing technique for fixed-dose combination mini-matrices.

    Science.gov (United States)

    Dierickx, L; Saerens, L; Almeida, A; De Beer, T; Remon, J P; Vervaet, C

    2012-08-01

    The aim of this study was to develop a multilayer (core/coat) dosage form via co-extrusion, the core providing sustained drug release and the coat immediate drug release. In this study polymers were selected which can be combined in a co-extruded dosage form. Several thermoplastic polymers were hot-melt extruded and evaluated for processability and macroscopic properties (surface smoothness, die swell). Metoprolol tartrate (MPT) and hydrochlorothiazide (HCT) were incorporated as sustained and immediate release model drugs, respectively. Based on the polymer screening experiments a combination of polycaprolactone (core) and polyethylene oxide (coat) was selected for co-extrusion trials, taking into account their drug release profiles and extrusion temperature (70 °C). This combination (containing 10% HCT in the coat and 45% MPT in the core) was successfully co-extruded (diameter core: 3 mm/thickness coat: 0.5 mm). Adhesion between the two polymer layers was good. HCT release from the coat was complete within 30 min, while MPT release was sustained over 24 h (55%, 70%, 85% and 100% after 4, 8, 12 and 2 4h, respectively). DSC, XRD and Raman spectroscopy revealed that MPT remained crystalline during extrusion, whereas HCT was dissolved in the polyethylene oxide matrix. The in vivo study revealed no significant differences between the experimental formulation and the reference formulation (Zok-Zid tablet). Fixed-dose combination mini-tablets with good in vitro and in vivo performance were successfully developed by means of co-extrusion, using a combination of polycaprolactone and polyethylene oxide.

  18. Second harmonic optical coherence tomography

    OpenAIRE

    Jiang,Yi; Tomov, Ivan; Wang, Yimin; Chen, Zhongping

    2004-01-01

    Second harmonic optical coherence tomography, which uses coherence gating of second-order nonlinear optical response of biological tissues for imaging, is described and demonstrated. Femtosecond laser pulses were used to excite second harmonic waves from collagen harvested from rat tail tendon and a reference nonlinear crystal. Second harmonic interference fringe signals were detected and used for image construction. Because of the strong dependence of second harmonic generation on molecular ...

  19. Coherence matrix of plasmonic beams

    DEFF Research Database (Denmark)

    Novitsky, Andrey; Lavrinenko, Andrei

    2013-01-01

    We consider monochromatic electromagnetic beams of surface plasmon-polaritons created at interfaces between dielectric media and metals. We theoretically study non-coherent superpositions of elementary surface waves and discuss their spectral degree of polarization, Stokes parameters, and the for...... of the spectral coherence matrix. We compare the polarization properties of the surface plasmonspolaritons as three-dimensional and two-dimensional fields concluding that the latter is superior....

  20. Coherence Studies for Synthetic Aperture Sonar

    Science.gov (United States)

    2014-09-30

    TITLE AND SUBTITLE Coherence Studies for Synthetic Aperture Sonar 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-13-1-0020 5c. PROGRAM...systematic look at, coherence. 15. SUBJECT TERMS Synthetic; Aperture Sonar , Coherence, Seafloor Scatter, Propagation Variability 16. SECURITY...reconstruction of the document. Coherence Studies for Synthetic Aperture Sonar Anthony P. Lyons The Pennsylvania State University Applied Research